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WO2023042686A1 - Composition adhésive et feuille adhésive - Google Patents

Composition adhésive et feuille adhésive Download PDF

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Publication number
WO2023042686A1
WO2023042686A1 PCT/JP2022/033117 JP2022033117W WO2023042686A1 WO 2023042686 A1 WO2023042686 A1 WO 2023042686A1 JP 2022033117 W JP2022033117 W JP 2022033117W WO 2023042686 A1 WO2023042686 A1 WO 2023042686A1
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Prior art keywords
weight
pressure
sensitive adhesive
less
monomer
Prior art date
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Ceased
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PCT/JP2022/033117
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English (en)
Japanese (ja)
Inventor
一輝 笹原
慎太郎 野依
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Nitto Denko Corp
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Nitto Denko Corp
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Priority to KR1020247011884A priority Critical patent/KR20240066270A/ko
Priority to CN202280062200.2A priority patent/CN117957294A/zh
Publication of WO2023042686A1 publication Critical patent/WO2023042686A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/04—Homopolymers or copolymers of esters
    • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
    • C08K5/0016—Plasticisers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
    • C08L25/02—Homopolymers or copolymers of hydrocarbons
    • C08L25/04—Homopolymers or copolymers of styrene
    • C08L25/06—Polystyrene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/08—Macromolecular additives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • C09J7/385—Acrylic polymers

Definitions

  • the present invention relates to an adhesive composition and an adhesive sheet.
  • pressure-sensitive adhesives also called pressure-sensitive adhesives; the same applies hereinafter
  • pressure-sensitive adhesives are widely used for the purposes of bonding, fixing, protection, etc. in various industrial fields such as home electric appliances, automobiles, various machines, electrical equipment, and electronic equipment.
  • display devices such as liquid crystal display devices and organic EL display devices, polarizing films, retardation films, cover window members, and other various light-transmitting members and other members are joined. The use to do is mentioned.
  • Patent Documents 1 and 2 are cited as technical documents relating to pressure-sensitive adhesives for optical members.
  • Patent Documents 1 and 2 disclose a pressure-sensitive adhesive composition mainly composed of a (meth)acrylic acid ester polymer containing a monomer having a plurality of aromatic rings as a monomer unit, and a pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition. and proposes to use a monomer having a plurality of aromatic rings to set the refractive index of the pressure-sensitive adhesive to 1.50 or more, particularly preferably 1.51 or more.
  • the materials to which adhesives are attached such as optical members, there are materials with high refractive indices.
  • the refractive index of the acrylic pressure-sensitive adhesive is usually about 1.47.
  • an adhesive having good flexibility can be preferably used depending on the application site and usage mode.
  • foldable displays and rollable displays have been put to practical use as displays such as organic EL displays used in electronic devices such as smartphones, and adhesives used for the above applications are adherends that can be repeatedly folded. It is necessary to have the flexibility to follow Adhesives with excellent flexibility easily follow and adhere to curved surfaces such as three-dimensional shapes, and are suitable for use in electronic devices having curved surfaces. If the flexibility of the pressure-sensitive adhesive having a high refractive index can be enhanced, it can be applied to the applications requiring the above-described flexibility and is useful.
  • high refractive index materials used as monomer components of adhesive polymers and additives for adhesives tend to have a high glass transition temperature, such as having aromatic rings. , the modulus tends to be higher and the flexibility tends to be lower. There is a trade-off between a high refractive index and a low elastic modulus in the design of pressure-sensitive adhesives.
  • adhesives containing high refractive index materials tend to have a high glass transition temperature as described above, so adhesive strength tends to be low. If the adhesive strength to the adherend is not sufficient, it is difficult to obtain adhesion to the adherend, and there is a possibility that the adhesion reliability of the joint portion may be lowered. It would be practically useful if a pressure-sensitive adhesive that has a high refractive index, a low elastic modulus, and an improved adhesive strength is provided.
  • the present invention was created in view of the above circumstances, and provides a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive having a high refractive index, a low elastic modulus, and improved adhesive strength.
  • a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition.
  • a pressure-sensitive adhesive composition containing an acrylic polymer containing an aromatic ring-containing monomer (A1) as a monomer component, a plasticizer, and an oligomer.
  • the pressure-sensitive adhesive composition having the above structure is suitable for forming a pressure-sensitive adhesive having a high refractive index because the monomer component constituting the acrylic polymer contains the aromatic ring-containing monomer (A1).
  • the pressure-sensitive adhesive composition contains a plasticizer, it is possible to form a pressure-sensitive adhesive having a low elastic modulus.
  • the pressure-sensitive adhesive composition contains an oligomer, the adhesive strength can be improved. According to the pressure-sensitive adhesive composition having the composition described above, it is possible to form a pressure-sensitive adhesive having a high refractive index, a low elastic modulus, and improved adhesive strength.
  • the oligomer has a weight average molecular weight (Mw) of 3000 or more and less than 50000.
  • Mw weight average molecular weight
  • the glass transition temperature (Tg) of the oligomer is 0°C or higher and 200°C or lower.
  • the oligomer is selected from (meth)acrylic oligomers and styrenic oligomers.
  • the effects of the technology disclosed herein are preferably realized.
  • the oligomer is contained at a ratio of 1 part by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the acrylic polymer.
  • the plasticizer is a compound that has two or more double bond-containing rings and is liquid at 30°C. Since the pressure-sensitive adhesive composition contains a compound that is liquid at 30° C. and has two or more double bond-containing rings as a plasticizer, it is easy to form a pressure-sensitive adhesive that has a high refractive index and a low elastic modulus.
  • the plasticizer has at least one ring selected from aromatic rings and heterocycles as the double bond-containing ring.
  • the plasticizer has a first double bond-containing ring and a second double bond-containing ring.
  • the first double bond-containing ring and the second double bond-containing ring are linked via a linking group having 1 to 5 atoms.
  • Such a plasticizer has a linking group between two or more double bond-containing rings, and thus tends to lower the elastic modulus of the pressure-sensitive adhesive while maintaining a high refractive index.
  • the content of the aromatic ring-containing monomer (A1) in the monomer component of the acrylic polymer is 50% by weight or more.
  • an adhesive comprising an adhesive layer made of any adhesive disclosed herein (which may be an adhesive formed from any adhesive composition disclosed herein) A sheet. Since the adhesive disclosed herein can achieve both a high refractive index and a low elastic modulus, the adhesive sheet containing the adhesive desirably has a high refractive index for use in foldable displays and the like, and can be used repeatedly. It is preferably used for bonding, fixing, protection, etc. in applications that require flexibility to withstand bending operations. In addition, since the pressure-sensitive adhesive has improved adhesive strength, it can adhere well to the adherend and have sufficient adhesion reliability.
  • FIG. 1 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to one embodiment
  • FIG. FIG. 3 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to another embodiment
  • FIG. 3 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to another embodiment
  • the “base polymer” of the adhesive refers to the main component of the rubber-like polymer contained in the adhesive.
  • rubber-like polymer refers to a polymer that exhibits rubber elasticity in a temperature range around room temperature.
  • main component refers to a component contained in an amount exceeding 50% by weight unless otherwise specified.
  • acrylic polymer refers to a polymer containing monomer units derived from a monomer having at least one (meth)acryloyl group in one molecule as monomer units constituting the polymer.
  • a monomer having at least one (meth)acryloyl group in one molecule is also referred to as "acrylic monomer”.
  • an acrylic polymer in this specification is defined as a polymer containing monomeric units derived from an acrylic monomer.
  • Typical examples of acrylic polymers include acrylic polymers in which more than 50% by weight (preferably more than 70% by weight, for example more than 90% by weight) of monomer components constituting the polymer are acrylic monomers.
  • the term "acrylic monomer” refers to a monomer having at least one (meth)acryloyl group in one molecule.
  • (meth)acryloyl group” is meant to comprehensively refer to acryloyl groups and methacryloyl groups. Therefore, the concept of an acrylic monomer as used herein can include both a monomer having an acryloyl group (acrylic monomer) and a monomer having a methacryloyl group (methacrylic monomer).
  • (meth)acrylic acid means acrylic acid and methacrylic acid
  • “(meth)acrylate” means acrylate and methacrylate, respectively. The same applies to other similar terms.
  • the pressure-sensitive adhesive composition disclosed herein is not particularly limited as long as it can form a pressure-sensitive adhesive containing an acrylic polymer (preferably a pressure-sensitive adhesive containing the acrylic polymer as a base polymer).
  • the pressure-sensitive adhesive composition is, for example, a solvent-based pressure-sensitive adhesive composition containing a pressure-sensitive adhesive-forming component in an organic solvent, or prepared to form a pressure-sensitive adhesive by curing with active energy rays such as ultraviolet rays and radiation.
  • Active energy ray-curable pressure-sensitive adhesive composition water-dispersed pressure-sensitive adhesive composition in which pressure-sensitive adhesive-forming components are dispersed in water, hot-melt type that is coated in a heat-melted state and forms pressure-sensitive adhesive when cooled to around room temperature It may be in various forms such as an adhesive composition.
  • the technology disclosed herein can be preferably implemented using a solvent-based pressure-sensitive adhesive composition.
  • the effects of the technique disclosed herein can be preferably realized.
  • the adhesive composition disclosed herein contains an aromatic ring-containing monomer (A1) as a monomer component constituting the acrylic polymer.
  • the "monomer component constituting the acrylic polymer” is contained in the pressure-sensitive adhesive composition in the form of a preformed polymer, or is contained in the pressure-sensitive adhesive composition in the form of an unpolymerized monomer. It means a monomer that constitutes the repeating unit of the acrylic polymer in the pressure-sensitive adhesive formed from the pressure-sensitive adhesive composition, whether or not it is included. That is, the monomer component constituting the acrylic polymer may be contained in the pressure-sensitive adhesive composition in any form of a polymer, an unpolymerized product, or a partially polymerized product. From the viewpoint of ease of preparation of the PSA composition, in some embodiments, the PSA composition contains substantially all of the monomer components (for example, 95% by weight or more, preferably 99% by weight or more) in the form of a polymer. things are preferred.
  • (Monomer (A1)) A compound containing at least one aromatic ring and at least one ethylenically unsaturated group in one molecule is used as the monomer (A1). As the monomer (A1), such compounds can be used singly or in combination of two or more.
  • Examples of the ethylenically unsaturated groups include (meth)acryloyl groups, vinyl groups, and (meth)allyl groups.
  • a (meth)acryloyl group is preferred from the viewpoint of polymerization reactivity, and an acryloyl group is more preferred from the viewpoint of flexibility and adhesiveness.
  • the monomer (A1) a compound having one ethylenically unsaturated group contained in one molecule (that is, a monofunctional monomer) is preferably used.
  • the number of aromatic rings contained in one molecule of the compound used as the monomer (A1) may be one, or two or more.
  • the upper limit of the number of aromatic rings is not particularly limited, and may be, for example, 16 or less.
  • the number of aromatic rings may be, for example, 12 or less, preferably 8 or less, and 6 or less, from the viewpoint of ease of preparation of the pressure-sensitive adhesive composition, transparency of the pressure-sensitive adhesive, and the like. is more preferable, and may be 5 or less, 4 or less, 3 or less, or 2 or less.
  • the aromatic ring possessed by the compound used as the monomer (A1) includes a benzene ring (which may be a benzene ring constituting part of a biphenyl structure or a fluorene structure); a naphthalene ring, an indene ring, an azulene ring, anthracene ring, and a phenanthrene ring.
  • the heteroatoms included as ring-constituting atoms in the above heterocycle may be one or more selected from the group consisting of nitrogen, sulfur and oxygen, for example.
  • the heteroatoms that make up the heterocycle can be one or both of nitrogen and sulfur.
  • the monomer (A1) may have a structure in which one or more carbon rings and one or more heterocycles are condensed, such as a dinaphthothiophene structure.
  • the aromatic ring may or may not have one or more substituents on the ring-constituting atoms.
  • the substituent includes an alkyl group, an alkoxy group, an aryloxy group, a hydroxyl group, a halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), a hydroxyalkyl group, a hydroxyalkyloxy group, and a glycidyloxy group. etc. are exemplified, but not limited to these.
  • substituents containing carbon atoms the number of carbon atoms contained in the substituent is preferably 1-4, more preferably 1-3, and can be, for example, 1 or 2.
  • the aromatic ring has no substituents on the ring-constituting atoms, or has one or more substituents selected from the group consisting of alkyl groups, alkoxy groups and halogen atoms (e.g., bromine atoms).
  • the fact that the aromatic ring of the monomer (A1) has a substituent on its ring-constituting atom means that the aromatic ring has a substituent other than a substituent having an ethylenically unsaturated group.
  • the aromatic ring and the ethylenically unsaturated group may be directly bonded or may be bonded via a linking group.
  • the linking group is, for example, an alkylene group, an oxyalkylene group, a poly(oxyalkylene) group, a phenyl group, an alkylphenyl group, an alkoxyphenyl group, or a structure in which one or more hydrogen atoms in these groups are substituted with hydroxyl groups. (eg, hydroxyalkylene group), oxy group (--O-- group), thiooxy group (--S-- group), and the like.
  • the aromatic ring and the ethylenically unsaturated group are directly attached or attached via a linking group selected from the group consisting of alkylene, oxyalkylene, and poly(oxyalkylene) groups.
  • Aromatic ring-containing monomers having a structure in which The number of carbon atoms in the alkylene group and the oxyalkylene group is preferably 1-4, more preferably 1-3, and can be, for example, 1 or 2.
  • the number of repeating oxyalkylene units in the poly(oxyalkylene) group may be, for example, 2-3.
  • Examples of compounds that can be preferably employed as the monomer (A1) include aromatic ring-containing (meth)acrylates and aromatic ring-containing vinyl compounds.
  • the aromatic ring-containing (meth)acrylate and the aromatic ring-containing vinyl compound can be used singly or in combination of two or more.
  • One or two or more aromatic ring-containing (meth)acrylates and one or two or more aromatic ring-containing vinyl compounds may be used in combination.
  • a monomer having two or more aromatic rings (preferably carbocyclic rings) in one molecule can be used because a high refractive index-increasing effect is likely to be obtained.
  • monomers having two or more aromatic rings in one molecule include monomers having a structure in which two or more non-condensed aromatic rings are bonded via a linking group, and two or more non-condensed aromatic rings.
  • Monomers having a structure in which rings are chemically bonded directly that is, not through other atoms
  • monomers having a condensed aromatic ring structure monomers having a fluorene structure, monomers having a dinaphthothiophene structure, monomers having a dibenzothiophene structure , etc.
  • the monomers containing multiple aromatic rings may be used singly or in combination of two or more.
  • the linking group is, for example, an oxy group (-O-), a thiooxy group (-S-), an oxyalkylene group (eg, -O-(CH 2 ) n - group, where n is 1 to 3, preferably 1).
  • a thiooxyalkylene group such as a —S—(CH 2 ) n — group, where n is 1 to 3, preferably 1), a linear alkylene group (ie, a —(CH 2 ) n — group, where n is 1 to 6, preferably 1 to 3), the above oxyalkylene group, the above thiooxyalkylene group and the above linear alkylene group in which the alkylene group is partially or completely halogenated, and the like.
  • preferred examples of the linking group include an oxy group, a thiooxy group, an oxyalkylene group and a linear alkylene group.
  • monomers having a structure in which two or more non-fused aromatic rings are bonded via a linking group include phenoxybenzyl (meth)acrylate (e.g., m-phenoxybenzyl (meth)acrylate), thiophenoxybenzyl (meth) Acrylate, benzylbenzyl (meth)acrylate and the like.
  • the monomer having a structure in which two or more non-fused aromatic rings are directly chemically bonded may be, for example, a biphenyl structure-containing (meth)acrylate, a triphenyl structure-containing (meth)acrylate, a vinyl group-containing biphenyl, or the like. Specific examples include o-phenylphenol (meth)acrylate and biphenylmethyl (meth)acrylate.
  • Examples of monomers having the condensed aromatic ring structure include naphthalene ring-containing (meth)acrylates, anthracene ring-containing (meth)acrylates, vinyl group-containing naphthalenes, and vinyl group-containing anthracene.
  • Specific examples include 1-naphthylmethyl (meth)acrylate (also known as 1-naphthalenemethyl (meth)acrylate), hydroxyethylated ⁇ -naphthol acrylate, 2-naphthoethyl (meth)acrylate, 2-naphthoxyethyl acrylate, 2 -(4-methoxy-1-naphthoxy)ethyl (meth)acrylate and the like.
  • the monomer having a fluorene structure examples include 9,9-bis(4-hydroxyphenyl)fluorene (meth)acrylate and 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (meth)acrylate. etc. Since the monomer having a fluorene structure includes a structural portion in which two benzene rings are directly chemically bonded, it is included in the concept of a monomer having a structure in which two or more non-fused aromatic rings are directly chemically bonded.
  • Examples of the monomer having a dinaphthothiophene structure include (meth)acryloyl group-containing dinaphthothiophene, vinyl group-containing dinaphthothiophene, (meth)allyl group-containing dinaphthothiophene, and the like. Specific examples include (meth)acryloyloxymethyldinaphthothiophene (for example, a compound having a structure in which CH 2 CH(R 1 )C(O)OCH 2 — is bound to the 5- or 6-position of the dinaphthothiophene ring.
  • R 1 is a hydrogen atom or a methyl group.
  • (meth)acryloyloxyethyldinaphthothiophene for example, at the 5- or 6-position of the dinaphthothiophene ring, CH 2 CH(R 1 )C(O) OCH(CH 3 )— or a compound having a structure in which CH 2 CH(R 1 )C(O)OCH 2 CH 2 — is bonded, where R 1 is a hydrogen atom or a methyl group
  • vinyldinaphthothiophene Formula example, compounds having a structure in which a vinyl group is bonded to the 5th or 6th position of the naphthothiophene ring), (meth)allyloxydinaphthothiophene, and the like.
  • the monomer having a dinaphthothiophene structure is included in the concept of the monomer having a condensed aromatic ring structure by including a naphthalene structure and by having a structure in which a thiophene ring and two naphthalene structures are condensed. be.
  • Examples of the monomer having a dibenzothiophene structure include (meth)acryloyl group-containing dibenzothiophene, vinyl group-containing dibenzothiophene, and the like.
  • a monomer having a dibenzothiophene structure is included in the concept of a monomer having a condensed aromatic ring structure because it has a structure in which a thiophene ring and two benzene rings are condensed. Neither the dinaphthothiophene structure nor the dibenzothiophene structure corresponds to structures in which two or more non-fused aromatic rings are directly chemically bonded.
  • a monomer having one aromatic ring (preferably carbocyclic ring) in one molecule is used as the monomer (A1).
  • a monomer having one aromatic ring in one molecule can be useful, for example, in improving the flexibility of the pressure-sensitive adhesive, adjusting the pressure-sensitive adhesive properties, and improving the transparency.
  • a single aromatic ring-containing monomer can be used alone or in combination of two or more.
  • a monomer having one aromatic ring in one molecule may be used in combination with a monomer containing multiple aromatic rings from the viewpoint of improving the refractive index of the pressure-sensitive adhesive.
  • Examples of monomers having one aromatic ring in one molecule include benzyl (meth)acrylate, methoxybenzyl (meth)acrylate, phenyl (meth)acrylate, ethoxylated phenol (meth)acrylate, phenoxypropyl (meth)acrylate 2-(4, 6-dibromo-2-s-butylphenoxy)ethyl (meth)acrylate, 2-(4,6-dibromo-2-isopropylphenoxy)ethyl (meth)acrylate, 6-(4,6-dibromo-2-s- Butylphenoxy)hexyl (meth)acrylate, 6-(4,6-dibromo-2-isopropylphenoxy)hexyl (meth)acrylate, 2,6-dibromo-4-nonylphenyl acrylate, 2,6-dibromo-4-dodecyl Bromine-substituted aromatic ring-containing (meth)acryl
  • the monomer (A1) a monomer having a structure in which an oxyethylene chain is interposed between the ethylenically unsaturated group and the aromatic ring in various aromatic ring-containing monomers as described above may be used.
  • a monomer having an oxyethylene chain interposed between an ethylenically unsaturated group and an aromatic ring in this manner can be understood as an ethoxylated product of the original monomer.
  • the number of repeating oxyethylene units ( --CH.sub.2CH.sub.2O-- ) in the oxyethylene chain is typically 1-4, preferably 1-3, more preferably 1-2, for example 1.
  • ethoxylated aromatic ring-containing monomers include ethoxylated o-phenylphenol (meth)acrylate, ethoxylated nonylphenol (meth)acrylate, ethoxylated cresol (meth)acrylate, phenoxyethyl (meth)acrylate, and phenoxydiethylene glycol. di(meth)acrylate and the like.
  • the content of the monomer containing multiple aromatic rings in the monomer (A1) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, or 40% by weight or more. In some aspects, the content of the monomer containing multiple aromatic rings in the monomer (A1) may be, for example, 50% by weight or more, and is preferably 70% by weight or more from the viewpoint of facilitating obtaining a higher refractive index. , 85% by weight or more, 90% by weight or more, or 95% by weight or more. Substantially 100% by weight of the monomer (A1) may be the multiple aromatic ring-containing monomer. That is, only one or two or more aromatic ring-containing monomers may be used as the monomer (A1).
  • the content of the monomer containing multiple aromatic rings in the monomer (A1) is less than 100% by weight. may be 98% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, 65% by weight or less, 50% by weight or less, or 25% by weight or less It may be 10% by weight or less.
  • the technology disclosed herein can also be practiced in a mode in which the content of the monomer containing multiple aromatic rings in the monomer (A1) is less than 5% by weight. A monomer containing multiple aromatic rings may not be used.
  • the content of the monomer containing multiple aromatic rings in the monomer component that constitutes the acrylic polymer is not particularly limited, and can be set so as to achieve a pressure-sensitive adhesive that achieves both the desired refractive index and elastic modulus.
  • the content of the monomer containing multiple aromatic rings in the monomer component may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more.
  • the content of the monomer containing multiple aromatic rings in the monomer component may be, for example, more than 35% by weight, or 50% by weight.
  • the content of the monomer containing multiple aromatic rings in the monomer component is advantageously about 99% by weight or less, considering the balance between high refractive index, low elastic modulus, and adhesive strength, and 98% by weight or less. It is preferably 96% by weight or less, more preferably 93% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, or 75% by weight or less. good.
  • the content of the monomer containing multiple aromatic rings in the monomer component may be 70% by weight or less, or 60% by weight. % by weight or less, 50% by weight or less, 40% by weight or less, 25% by weight or less, 15% by weight or less, or 5% by weight or less.
  • the technology disclosed herein can also be practiced in a mode in which the content of the monomer containing multiple aromatic rings in the monomer component is less than 3% by weight.
  • the content of the single aromatic ring-containing monomer in the monomer (A1) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, or 40% by weight or more. In some aspects, the content of the single aromatic ring-containing monomer in the monomer (A1) may be, for example, 50% by weight or more, and is preferably 70% by weight or more from the viewpoint of facilitating obtaining a higher refractive index. , 85% by weight or more, 90% by weight or more, or 95% by weight or more. Substantially 100% by weight of the monomer (A1) may be a single aromatic ring-containing monomer. That is, as the monomer (A1), only one or more monomers containing a single aromatic ring may be used.
  • the content of the monomer containing a single aromatic ring in the monomer (A1) is less than 100% by weight. may be 98% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, 65% by weight or less, 50% by weight or less, or 25% by weight or less Well, it may be 10% by weight or less.
  • the technology disclosed herein can also be practiced in a mode in which the content of the single aromatic ring-containing monomer in the monomer (A1) is less than 5% by weight. A single aromatic ring-containing monomer may not be used.
  • the content of the single aromatic ring-containing monomer in the monomer component that constitutes the acrylic polymer is not particularly limited, and can be set so as to achieve a pressure-sensitive adhesive that achieves both the desired refractive index and elastic modulus.
  • the content of the single aromatic ring-containing monomer in the monomer component may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more.
  • the content of the monomer containing a single aromatic ring in the monomer component may be, for example, more than 35% by weight, and 50% by weight or more. (e.g.
  • the content of the monomer containing a single aromatic ring in the above monomer component may be approximately 99% by weight or less, or 98% by weight or less, in consideration of the balance between high refractive index, low elastic modulus, and adhesive strength. more preferably 96% by weight or less, 93% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, or 75% by weight or less.
  • the content of the monomer containing a single aromatic ring in the monomer component may be 70% by weight or less, or 60% by weight. % by weight or less, 50% by weight or less, 40% by weight or less, 25% by weight or less, 15% by weight or less, or 5% by weight or less.
  • the technology disclosed herein can also be practiced in a mode in which the content of the single aromatic ring-containing monomer in the monomer component is less than 3% by weight.
  • a high refractive index monomer can be preferably employed as at least part of the monomer (A1).
  • “high refractive index monomer” refers to a monomer having a refractive index of, for example, approximately 1.510 or higher, preferably approximately 1.530 or higher, and more preferably approximately 1.550 or higher.
  • the upper limit of the refractive index of the high refractive index monomer is not particularly limited, it is, for example, 3.000 or less from the viewpoint of ease of preparation of the pressure-sensitive adhesive composition and compatibility with flexibility suitable as a pressure-sensitive adhesive. It may be 0.500 or less, 2.000 or less, 1.900 or less, 1.800 or less, or 1.700 or less.
  • the high refractive index monomers can be used singly or in combination of two or more.
  • the refractive index of the monomer is measured using an Abbe refractometer under conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C.
  • As the Abbe refractometer model "DR-M4" manufactured by ATAGO or its equivalent can be used. If the manufacturer or the like provides the nominal value of the refractive index at 25° C., the nominal value can be adopted.
  • m-phenoxybenzyl acrylate (refractive index: 1.566, homopolymer Tg: -35°C), 1-naphthylmethyl acrylate (refractive index: 1.595, homopolymer Tg: 31°C), Ethoxylated o-phenylphenol acrylate (repeating number of oxyethylene unit: 1, refractive index: 1.578), benzyl acrylate (refractive index (nD20): 1.519, homopolymer Tg: 6°C), phenoxyethyl acrylate (Refractive index (nD20): 1.517, homopolymer Tg: 2 ° C.), phenoxydiethylene glycol acrylate (refractive index: 1.510, homopolymer Tg: -35 ° C.), 6-acryloyloxymethyldinaphthothiophene ( 6MDNTA, refractive index: 1.75), 6-methacryloyloxymethyldinaphthothiophene
  • the content of the high refractive index monomer (that is, the aromatic ring-containing monomer having a refractive index of about 1.510 or higher, preferably about 1.530 or higher, more preferably about 1.550 or higher) in the monomer (A1) is particularly For example, it may be 5% by weight or more, 25% by weight or more, 35% by weight or more, or 40% by weight or more.
  • the content of the high refractive index monomer in the monomer (A1) may be, for example, 50% by weight or more, preferably 70% by weight or more, from the viewpoint of easily obtaining a higher refractive index. , 85% by weight or more, 90% by weight or more, or 95% by weight or more.
  • Substantially 100% by weight of the monomers (A1) may be high refractive index monomers. Further, in some embodiments, for example, from the viewpoint of balancing a high refractive index, a low elastic modulus, and adhesive strength, the content of the high refractive index monomer in the monomer (A1) is less than 100% by weight. 98% by weight or less, 90% by weight or less, 80% by weight or less, or 65% by weight or less.
  • the content of the high-refractive-index monomer in the monomer component that constitutes the acrylic polymer is not particularly limited, and can be set so as to achieve a pressure-sensitive adhesive that achieves both the desired refractive index and elastic modulus. In addition, if necessary, it can be set in consideration of coexistence with adhesive properties (eg, adhesive strength, etc.) and/or optical properties (eg, total light transmittance, haze value, etc.).
  • the content of the high refractive index monomer in the monomer component may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more.
  • the content of the high refractive index monomer in the monomer component constituting the acrylic polymer may be, for example, more than 35% by weight, and from the viewpoint of facilitating obtaining a higher refractive index, it is more than 50% by weight.
  • it is more than 60% by weight, it may be 75% by weight or more, it may be 85% by weight or more, it may be 90% by weight or more, it may be 95% by weight or more.
  • the content of the high refractive index monomer in the monomer component is advantageously 99% by weight or less, and 98% by weight or less, from the viewpoint of achieving a good balance between a high refractive index, a low elastic modulus, and adhesive strength. It is preferably 96% by weight or less, more preferably 93% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, or 75% by weight or less. .
  • an aromatic ring-containing monomer having a homopolymer Tg of 10°C or lower (hereinafter sometimes referred to as "monomer L") is employed as at least part of the monomer (A1).
  • the content of the aromatic ring-containing monomer (A1) in the monomer component (in particular, the aromatic ring-containing monomer (A1) corresponding to at least one of the above-described multiple aromatic ring-containing monomer, single aromatic ring-containing monomer and high refractive index monomer)
  • the storage elastic modulus G' of the pressure-sensitive adhesive generally tends to increase when increased, the increase in the storage elastic modulus G' can be suppressed by adopting the monomer L as part or all of the monomer (A1). can.
  • the Tg of the monomer L may be, for example, 5° C. or lower, 0° C. or lower, ⁇ 10° C. or lower, ⁇ 20° C. or lower, or ⁇ 25° C. or lower.
  • the lower limit of Tg of monomer L is not particularly limited.
  • the Tg of the monomer L may be -70°C or higher, -55°C or higher, or -45°C or higher.
  • the Tg of monomer L may be, for example, ⁇ 30° C. or higher, ⁇ 10° C. or higher, 0° C. or higher, or 3° C. or higher.
  • Monomer L can be used individually by 1 type or in combination of 2 or more types.
  • aromatic ring-containing monomers that can be used as monomer L include m-phenoxybenzyl acrylate (Tg of homopolymer: ⁇ 35° C.), benzyl acrylate (Tg of homopolymer: 6° C.), phenoxyethyl acrylate (Tg of homopolymer: Tg: 2°C) and phenoxydiethylene glycol acrylate (Tg of homopolymer: -35°C).
  • the content of the monomer L in the monomer (A1) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, or 40% by weight or more.
  • the content of the monomer L in the monomer (A1) is, for example, 50% by weight or more from the viewpoint of facilitating the production of a pressure-sensitive adhesive having both a high refractive index and a low elastic modulus at a higher level.
  • it is preferably 60% by weight or more, may be 70% by weight or more, may be 75% by weight or more, may be 85% by weight or more, may be 90% by weight or more, or may be 95% by weight. It can be more than that.
  • Substantially 100% by weight of monomer (A1) may be monomer L. Further, in some aspects, for example, from the viewpoint of balancing a high refractive index, a low elastic modulus, and adhesive strength in a well-balanced manner, the content of the monomer L in the monomer (A1) may be less than 100% by weight. , 98% by weight or less, 90% by weight or less, 80% by weight or less, or 65% by weight or less.
  • the content of the monomer L in the monomer component constituting the acrylic polymer may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more.
  • the content of the monomer L in the monomer component may be, for example, more than 35% by weight, from the viewpoint of easily obtaining a pressure-sensitive adhesive that achieves both a high refractive index and a low elastic modulus at a higher level, From the viewpoint of improving the refractive index, it is advantageous that the content is more than 50% by weight, preferably more than 60% by weight. % by weight or more.
  • the content of the monomer L in the monomer component is advantageously about 99% by weight or less from the viewpoint of balancing a high refractive index, a low elastic modulus, and an adhesive strength, and is set to 98% by weight or less. More preferably 96% by weight or less, 93% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, or 75% by weight or less.
  • the glass transition temperature Tg A1 based on the composition of the monomer (A1) is suitably about 20° C. or lower, preferably 10° C. or lower, from the viewpoint of lowering the elastic modulus. It may be 5° C. or lower, 0° C. or lower, ⁇ 10° C. or lower, ⁇ 20° C. or lower, or ⁇ 25° C. or lower.
  • the lower limit of the glass transition temperature Tg A1 is not particularly limited.
  • the glass transition temperature Tg A1 may be -70° C. or higher, -55° C. or higher, or -45° C. or higher in consideration of the balance with the refractive index improvement effect.
  • the technology disclosed herein can also be suitably practiced in embodiments where the glass transition temperature Tg A1 is, for example, -40°C or higher, -35°C or higher, -33°C or higher, -30°C or higher, or -25°C or higher.
  • the glass transition temperature Tg A1 may be, for example, ⁇ 10° C. or higher, 0° C. or higher, or 3° C. or higher.
  • the glass transition temperature Tg A1 based on the composition of the monomer (A1) is the Tg determined by the Fox formula described later based on the composition of only the monomer (A1) among the monomer components constituting the acrylic polymer.
  • the glass transition temperature Tg A1 is obtained by applying the Fox formula to only the monomer (A1) among the monomer components constituting the acrylic polymer, and the glass of the homopolymer of each aromatic ring-containing monomer used as the monomer (A1). It can be calculated from the transition temperature and the weight fraction of each aromatic ring-containing monomer in the total amount of the monomers (A1).
  • the Tg of the homopolymer of the monomer and the glass transition temperature Tg A1 match.
  • the aromatic ring-containing monomer (A1) is a combination of monomer L (that is, an aromatic ring-containing monomer whose homopolymer Tg is 10°C or lower) and monomer H whose Tg is higher than 10°C.
  • the Tg of monomer H may be, for example, greater than 10°C, greater than 15°C, or greater than 20°C.
  • the amount ratio of the monomer L and the monomer H used can be set so as to suitably exhibit such effects, and is not particularly limited. For example, it is preferable to set the usage amount ratio of the monomer L and the monomer H so as to satisfy one of the glass transition temperatures Tg A1 described above.
  • the aromatic ring-containing monomer (A1) can be preferably selected from compounds that do not contain a structure (for example, a biphenyl structure) in which two or more non-fused aromatic rings are directly chemically bonded.
  • a structure for example, a biphenyl structure
  • the content of a compound containing a structure in which two or more non-fused aromatic rings are directly chemically bonded is less than 5% by weight (more preferably less than 3% by weight, and may be 0% by weight).
  • An acrylic polymer composed of is preferred.
  • Restricting the amount of the compound containing a structure in which two or more non-fused aromatic rings are directly chemically bonded in this way enables the development of a pressure-sensitive adhesive that achieves a good balance between a high refractive index, a low elastic modulus, and adhesive strength. It can be advantageous from the viewpoint of realization.
  • the content of the monomer (A1) in the monomer component constituting the acrylic polymer is not particularly limited, and the desired refractive index and elastic modulus, adhesive properties (e.g., adhesive strength, etc.) and / or optical properties (e.g., total ray transmittance, haze value, etc.) can be set so as to realize an adhesive.
  • the content of the monomer (A1) in the monomer component may be, for example, 30% by weight or more, preferably 50% by weight or more, more preferably 60% by weight or more, and 70% by weight. % or more.
  • the content of the monomer (A1) in the monomer component constituting the acrylic polymer may be, for example, more than 70% by weight, suitably 75% by weight or more, and higher From the viewpoint of facilitating obtaining a refractive index, the content is preferably 80% by weight or more, may be 85% by weight or more, may be 90% by weight or more, or may be 95% by weight or more.
  • the content of the monomer (A1) in the monomer component is typically less than 100% by weight, and is about 99% by weight or less from the viewpoint of balancing a high refractive index, a low elastic modulus, and adhesive strength in a well-balanced manner.
  • the content is preferably 98% by weight or less, more preferably 96% by weight or less, may be 93% by weight or less, or may be 90% by weight or less.
  • the content of the monomer (A1) in the monomer component may be less than 90% by weight, and may be less than 85% by weight, from the viewpoint of facilitating the realization of higher adhesive properties and/or optical properties (e.g., transparency). %, less than 80% by weight, or less than 75% by weight.
  • the monomer component constituting the acrylic polymer may further contain a monomer (A2) in addition to the monomer (A1).
  • the monomer (A2) is a monomer corresponding to at least one of a monomer having a hydroxyl group (hydroxyl group-containing monomer) and a monomer having a carboxy group (carboxy group-containing monomer).
  • the hydroxyl group-containing monomer is a compound having at least one hydroxyl group and at least one ethylenically unsaturated group in one molecule.
  • the carboxy group-containing monomer is a compound containing at least one carboxy group and at least one ethylenically unsaturated group in one molecule.
  • the monomer (A2) can be useful for introducing cross-linking points into the acrylic polymer and imparting appropriate cohesiveness to the pressure-sensitive adhesive.
  • Monomer (A2) can be used individually by 1 type or in combination of 2 or more types.
  • Monomer (A2) is typically a monomer containing no aromatic ring.
  • Examples of the ethylenically unsaturated groups possessed by the monomer (A2) include (meth)acryloyl groups, vinyl groups, and (meth)allyl groups.
  • a (meth)acryloyl group is preferable from the viewpoint of polymerization reactivity, and an acryloyl group is more preferable from the viewpoint of low elastic modulus and adhesiveness.
  • a compound containing one ethylenically unsaturated group in one molecule that is, a monofunctional monomer is preferably used.
  • hydroxyl group-containing monomers examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, (meth) ) Hydroxy (meth)acrylates such as 8-hydroxyoctyl acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, etc. Examples include, but are not limited to, alkyl.
  • hydroxyl group-containing monomers examples include 4-hydroxybutyl acrylate (Tg: -40°C) and 2-hydroxyethyl acrylate (Tg: -15°C). From the viewpoint of improving flexibility in the room temperature range, 4-hydroxybutyl acrylate having a lower Tg is more preferable.
  • 50 wt% or more (eg, greater than 50 wt%, greater than 70 wt%, or greater than 85 wt%) of monomer (A2) can be 4-hydroxybutyl acrylate.
  • a hydroxyl-containing monomer can be used individually by 1 type or in combination of 2 or more types.
  • the hydroxyl-containing monomer may be one or more selected from compounds having no methacryloyl group.
  • Preferred examples of hydroxyl group-containing monomers having no methacryloyl group include the various hydroxyalkyl acrylates described above. For example, more than 50% by weight, more than 70% by weight, or more than 85% by weight of the hydroxyl group-containing monomer used as the monomer (A2) is preferably hydroxyalkyl acrylate.
  • hydroxyalkyl acrylates can introduce hydroxy groups into the acrylic polymer that help provide cross-linking points and moderate cohesiveness, and at room temperature compared to using only the corresponding hydroxyalkyl methacrylates. It is easy to obtain an adhesive with good flexibility and adhesiveness in the area.
  • carboxy group-containing monomers examples include acrylic monomers such as (meth)acrylic acid, carboxyethyl (meth)acrylate, and carboxypentyl (meth)acrylate, as well as itaconic acid, maleic acid, fumaric acid, crotonic acid, Examples include, but are not limited to, isocrotonic acid and the like.
  • carboxy group-containing monomers that can be preferably used include acrylic acid and methacrylic acid.
  • a carboxy group-containing monomer can be used individually by 1 type or in combination of 2 or more types.
  • a hydroxyl group-containing monomer and a carboxy group-containing monomer may be used in combination.
  • the content of the monomer (A2) in the monomer component constituting the acrylic polymer is not particularly limited and can be set according to the purpose.
  • the content of the monomer (A2) can be, for example, 0.01% by weight or more, 0.1% by weight or more, or 0.5% by weight or more.
  • the content of the monomer (A2) is preferably 1% by weight or more, may be 2% by weight or more, or may be 4% by weight or more.
  • the upper limit of the content of the monomer (A2) in the monomer component is set so that the sum with the content of the monomer (A1) does not exceed 100% by weight.
  • the content of the monomer (A2) is, for example, 30% by weight or less or 25% by weight or less. From the viewpoint of facilitating conversion, it is preferably 20% by weight or less, more preferably 15% by weight or less, may be less than 12% by weight, may be less than 10% by weight, or may be less than 7% by weight. . In some preferred embodiments, the content of the monomer (A2) is less than 5% by weight, more preferably less than 3% by weight, and 1.5% by weight from the viewpoint of lowering the elastic modulus of the pressure-sensitive adhesive. It may be below.
  • the total content of the monomer (A1) and the monomer (A2) in the monomer component constituting the acrylic polymer may be, for example, 31% by weight or more, preferably 51% by weight or more, and may be 61% by weight or more. , 71% by weight or more.
  • the total content of the monomer (A1) and the monomer (A2) in the monomer components constituting the acrylic polymer is, for example, 76% by weight from the viewpoint of favorably exhibiting the effects of these monomers. 81% by weight or more, 86% by weight or more, 91% by weight or more, 96% by weight or more, 99% by weight or more, or substantially 100% by weight.
  • the monomer component constituting the acrylic polymer may further contain an alkyl (meth)acrylate (hereinafter also referred to as "monomer (A3)") in addition to the monomer (A1).
  • Monomer (A3) can help reduce the modulus of the adhesive. It can also help improve the compatibility of additives in the adhesive and adhesive properties such as adhesive strength.
  • Monomer (A3) can be used individually by 1 type or in combination of 2 or more types.
  • an alkyl (meth)acrylate having a straight or branched chain alkyl group having 1 to 20 carbon atoms (ie C 1-20 ) at the ester end can be preferably used.
  • C 1-20 alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-(meth)acrylate, Butyl, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, (meth)acrylate ) heptyl acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isoo
  • an alkyl (meth)acrylate having a homopolymer Tg of -20°C or lower is preferably employed as at least part of the monomer (A3).
  • Such low Tg alkyl (meth)acrylates can help reduce the elastic modulus of the pressure-sensitive adhesive. It can also help improve adhesive properties such as adhesive strength.
  • the lower limit of the Tg of the alkyl (meth)acrylate is not particularly limited, and may be -85°C or higher, -75°C or higher, -65°C or higher, or -60°C or higher.
  • Specific examples of the low Tg alkyl (meth)acrylate include n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), isononyl acrylate (iNA), and the like.
  • C 4-8 alkyl (meth)acrylates As monomer (A3), it is preferred to use C 4-8 alkyl (meth)acrylates as monomer (A3). Among them, the use of C 4-8 alkyl acrylate is more preferable.
  • the C 4-8 alkyl (meth)acrylates can be used singly or in combination of two or more. The use of C 4-8 alkyl (meth)acrylate tends to reduce the elastic modulus of the pressure-sensitive adhesive and to provide good pressure-sensitive adhesive properties (adhesive strength, etc.).
  • the proportion of the C 4-8 alkyl (meth)acrylate among the alkyl (meth)acrylates contained in the monomer component is 30% by weight or more. is preferably 50% by weight or more, more preferably 70% by weight or more, still more preferably 90% by weight or more, and may be substantially 100% by weight.
  • C 1-6 alkyl (meth)acrylates can be preferably used as monomer (A3).
  • the use of C 1-6 alkyl (meth)acrylates allows the storage modulus in each temperature range to be adjusted. For example, it is possible to set the storage elastic modulus in the high temperature range to be relatively high, or to suppress an increase in the difference in storage elastic modulus between the low temperature range and the high temperature range.
  • the C 1-6 alkyl (meth)acrylate tends to be excellent in copolymerizability with the monomer (A1).
  • the C 1-6 alkyl (meth)acrylates may be used singly or in combination of two or more.
  • the C 1-6 alkyl (meth)acrylate is preferably a C 1-6 alkyl acrylate, more preferably a C 2-6 alkyl acrylate, and even more preferably a C 4-6 alkyl acrylate.
  • the C 1-6 alkyl (meth)acrylate is preferably a C 1-4 alkyl (meth)acrylate, more preferably a C 2-4 alkyl (meth)acrylate, even more preferably is a C 2-4 alkyl acrylate.
  • Preferred examples of C 1-6 alkyl (meth)acrylates include BA.
  • the content of C 1-6 alkyl (meth)acrylate in the monomer component constituting the acrylic polymer may be, for example, 1% by weight or more, 3% by weight or more, 5% by weight or more, or 8% by weight. It can be more than that.
  • the content of the C 1-6 alkyl (meth)acrylate may be 10% by weight or more, or 15% by weight or more, from the viewpoint of lowering the elastic modulus, adhesive strength, etc. It may be 20% by weight or more, or 25% by weight or more (for example, 30% by weight or more).
  • the upper limit of the C 1-6 alkyl (meth)acrylate content in the monomer component is, for example, less than 50% by weight, and may be less than 35% by weight.
  • the content of the C 1-6 alkyl (meth)acrylate is, for example, 24% by weight or less, preferably less than 20% by weight, and 17% by weight. It is more preferably less than 12% by weight, less than 7% by weight, less than 3% by weight, or less than 1% by weight.
  • the technology disclosed herein can also be practiced in an embodiment that does not substantially use C 1-6 alkyl (meth)acrylates.
  • C 7-12 alkyl (meth)acrylates can be preferably used as monomer (A3).
  • Storage modulus can be favorably reduced by the use of C 7-12 alkyl (meth)acrylates.
  • the C 7-12 alkyl (meth)acrylates can be used singly or in combination of two or more.
  • the C 7-12 alkyl (meth)acrylates are preferably C 7-10 alkyl acrylates, more preferably C 7-9 alkyl acrylates, and even more preferably C 8 alkyl acrylates.
  • Suitable examples of C 7-12 alkyl (meth)acrylates include 2EHA.
  • the content of C 7-12 alkyl (meth)acrylate in the monomer component constituting the acrylic polymer may be, for example, 1% by weight or more, 3% by weight or more, 5% by weight or more, or 8% by weight. It can be more than that.
  • the content of the C 7-12 alkyl (meth)acrylate may be 10% by weight or more, or 15% by weight or more, from the viewpoint of lowering the elastic modulus, adhesive strength, etc. It may be 20% by weight or more, or 25% by weight or more (for example, 30% by weight or more).
  • the upper limit of the C 7-12 alkyl (meth)acrylate content in the monomer component is, for example, less than 50% by weight, and may be less than 35% by weight.
  • the content of the C 7-12 alkyl (meth)acrylate is, for example, 24% by weight or less, preferably less than 20% by weight, and 17% by weight. It is more preferably less than 12% by weight, less than 7% by weight, less than 3% by weight, or less than 1% by weight.
  • the technology disclosed herein can also be practiced in a manner substantially free of C 7-12 alkyl (meth)acrylates.
  • At least part of the monomer (A3) is preferably an alkyl acrylate from the viewpoint of lowering the elastic modulus.
  • the use of alkyl acrylates is also advantageous in terms of adhesive properties such as adhesive strength.
  • An aspect in which only one or two or more alkyl acrylates are used as the monomer (A3) and no alkyl methacrylate is used may be employed.
  • the content of the alkyl (meth)acrylate (monomer (A3)) in the monomer component is set so that the effect of use thereof is appropriately exhibited. can do.
  • the content of the alkyl (meth)acrylate (monomer (A3)) may be, for example, 1% by weight or more, 3% by weight or more, 5% by weight or more, or 8% by weight. It can be more than that.
  • the content of the monomer (A3) in the monomer component may be, for example, 10% by weight or more, or even 15% by weight or more, from the viewpoint of reducing the elastic modulus of the adhesive and adhesive strength. It may be 20% by weight or more, or 25% by weight or more (for example, 30% by weight or more).
  • the upper limit of the content of the monomer (A3) in the monomer component is set so that the total content of the monomers (A1) and (A2) does not exceed 100% by weight, for example, less than 50% by weight, and 40% by weight. % or less, or less than 35% by weight.
  • the content of the monomer (A3) can be, for example, 24% by weight or less.
  • the content of the monomer (A3) in the monomer component is limited, and the content of the monomer (A1) is increased relatively. It is advantageous to From this point of view, the content of the monomer (A3) may be less than 23% by weight, less than 20% by weight, less than 17% by weight, less than 12% by weight, or 7% by weight of the monomer component. It may be less than 3% by weight, or less than 1% by weight.
  • the technology disclosed herein can be preferably practiced even in a mode in which the monomer (A3) is not substantially used.
  • the monomer component constituting the acrylic polymer may optionally contain monomers other than the monomers (A1), (A2) and (A3) (hereinafter referred to as "other monomers").
  • the above-mentioned other monomers can be used, for example, for the purposes of adjusting the Tg of the acrylic polymer, adjusting the adhesive performance, improving the compatibility in the adhesive layer, and the like. These other monomers may be used singly or in combination of two or more.
  • Examples of the other monomers include monomers having functional groups other than hydroxyl groups and carboxy groups (functional group-containing monomers).
  • other monomers capable of improving the cohesive strength and heat resistance of the adhesive include sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, cyano group-containing monomers, and the like.
  • amide group-containing monomers For example, (meth)acrylamide, N-methylol (meth)acrylamide, etc.), amino group-containing monomers (e.g., aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, etc.), nitrogen atom-containing rings Monomers having (e.g., N-vinyl-2-pyrrolidone, N-(meth)acryloylmorpholine, etc.), imide group-containing monomers, epoxy group-containing monomers, keto group-containing monomers, isocyanate group-containing monomers, alkoxysilyl group-containing monomers, etc. mentioned.
  • vinyl ester monomers such as vinyl acetate; non-aromatic ring-containing (meth)acrylates such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; ethylene, Olefinic monomers such as butadiene and isobutylene; Chlorine-containing monomers such as vinyl chloride; Alkoxy group-containing monomers such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and ethoxyethoxyethyl (meth)acrylate; Vinyl ethers such as methyl vinyl ether system monomer; and the like.
  • ethoxyethoxyethyl acrylate also known as ethyl carbitol acrylate, Tg of homopolymer: -67°C.
  • the amount used is not particularly limited, and can be appropriately set within a range in which the total amount of the monomer components does not exceed 100% by weight.
  • the content of the other monomer in the monomer component can be, for example, approximately 35% by weight or less, and approximately 25% by weight or less (for example, 0 ⁇ 25% by weight), approximately 20% by weight or less (for example, 0 to 20% by weight), and approximately 10% by weight or less (for example, 0 to 10% by weight).
  • it is about 5% by weight or less, for example about 1% by weight or less.
  • the technology disclosed herein can be preferably practiced in a mode in which the monomer component does not substantially contain the above-mentioned other monomers.
  • the monomer component that constitutes the acrylic polymer may have a composition in which the amount of the methacryloyl group-containing monomer used is suppressed to a predetermined amount or less.
  • the amount of the methacryloyl group-containing monomer used in the monomer component may be, for example, less than 5% by weight, less than 3% by weight, less than 1% by weight, or less than 0.5% by weight. Restricting the amount of the methacryloyl group-containing monomer to be used in this way can be advantageous from the viewpoint of achieving a pressure-sensitive adhesive that achieves a good balance between flexibility and adhesiveness and a high refractive index.
  • the monomer component that constitutes the acrylic polymer may have a composition that does not contain a methacryloyl group-containing monomer (for example, a composition that consists only of an acryloyl group-containing monomer).
  • the amount of the carboxy group-containing monomer used in the monomer component constituting the acrylic polymer is limited from the viewpoint of suppressing the coloring or discoloration (eg, yellowing) of the pressure-sensitive adhesive.
  • the amount of the carboxy group-containing monomer used in the monomer component may be, for example, less than 1% by weight, less than 0.5% by weight, less than 0.3% by weight, less than 0.1% by weight, and 0 less than 0.05% by weight.
  • the amount of the carboxy group-containing monomer used is limited in this way is due to the fact that metal materials that can be placed in contact with or in close proximity to the adhesive disclosed herein (for example, metal wiring that can be present on the adherend, It is also advantageous from the viewpoint of suppressing corrosion of metal films, etc.).
  • the technology disclosed herein can be carried out in a mode in which the monomer component constituting the acrylic polymer does not contain a carboxy group-containing monomer.
  • the monomer component constituting the acrylic polymer has an acidic functional group (including a carboxy group, a sulfonic acid group, a phosphoric acid group, etc.). preferably restricted.
  • the amount of the acidic functional group-containing monomer used in the monomer component of this embodiment the above-mentioned preferred amount of the carboxy group-containing monomer can be applied.
  • the technology disclosed herein can be preferably practiced in an aspect in which the monomer component does not contain an acidic group-containing monomer (that is, an aspect in which the acrylic polymer is acid-free).
  • the monomer component constituting the acrylic polymer preferably has a composition such that the glass transition temperature Tg T based on the composition of the monomer component is about 15° C. or less.
  • the glass temperature Tg T is preferably 10° C. or lower, more preferably 5° C. or lower, even more preferably 1° C. or lower, and may be 0° C. or lower.
  • the glass temperature Tg T may be ⁇ 10° C. or lower, ⁇ 15° C. or lower, ⁇ 25° C. or lower, ⁇ 30° C. or lower, or ⁇ 35° C. or lower. It's okay.
  • a low glass transition temperature Tg T can be advantageous from the viewpoint of lowering the elastic modulus of the pressure-sensitive adhesive.
  • the glass transition temperature Tg T may be, for example, ⁇ 60° C. or higher, and is preferably ⁇ 50° C. or higher, more preferably more than ⁇ 45° C., from the viewpoint of facilitating the increase in the refractive index of the pressure-sensitive adhesive. It may be above -40°C. In some preferred embodiments, the glass temperature Tg T may be greater than -30°C, greater than -25°C, greater than -20°C, or greater than -10°C.
  • a pressure-sensitive adhesive having both a high refractive index and a low elastic modulus can be preferably formed by using an acrylic polymer having a composition having a glass temperature Tg T within the above range.
  • the glass transition temperature Tg T means the glass transition temperature determined by the Fox formula based on the composition of the above-mentioned monomer components, unless otherwise specified.
  • Tg is the glass transition temperature of the copolymer (unit: K)
  • Wi is the weight fraction of the monomer i in the copolymer (weight-based copolymerization ratio)
  • Tgi is the homopolymer of the monomer i.
  • the glass transition temperature (unit: K).
  • K glass transition temperature of the homopolymer used for calculating the Tg
  • the value described in known materials such as "Polymer Handbook” (3rd edition, John Wiley & Sons, Inc., 1989) is used. For monomers for which multiple values are listed in the above Polymer Handbook, the highest value is adopted. If the Tg of the homopolymer is not described in known documents, the value obtained by the measurement method described in JP-A-2007-51271 shall be used.
  • the method for obtaining an acrylic polymer composed of such monomer components is not particularly limited, and solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, photopolymerization, etc.
  • Various polymerization methods known as methods for synthesizing acrylic polymers can be appropriately employed.
  • a solution polymerization method can be preferably employed.
  • the polymerization temperature at the time of solution polymerization can be appropriately selected according to the type of monomer and solvent used, the type of polymerization initiator, etc. ° C.).
  • the solvent (polymerization solvent) used for solution polymerization can be appropriately selected from conventionally known organic solvents.
  • aromatic compounds such as toluene (typically aromatic hydrocarbons); acetic esters such as ethyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; 1,2-dichloroethane and the like Halogenated alkanes; lower alcohols such as isopropyl alcohol (e.g., monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; Any one kind of solvent or a mixed solvent of two or more kinds can be used.
  • the initiator used for polymerization can be appropriately selected from conventionally known polymerization initiators according to the type of polymerization method.
  • one or more azo polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) can be preferably used.
  • Other examples of polymerization initiators include persulfates such as potassium persulfate; peroxide initiators such as benzoyl peroxide and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; aromatic carbonyl compounds. ; and the like.
  • Still another example of the polymerization initiator is a redox initiator obtained by combining a peroxide and a reducing agent.
  • a polymerization initiator can be used individually by 1 type or in combination of 2 or more types.
  • the amount of the polymerization initiator used may be a normal amount, for example, about 0.005 to 1 part by weight (typically about 0.01 to 1 part by weight) per 100 parts by weight of the monomer component. ).
  • chain transfer agents can be used for the above polymerization, if necessary.
  • mercaptans such as n-dodecylmercaptan, t-dodecylmercaptan, thioglycolic acid and ⁇ -thioglycerol can be used.
  • a chain transfer agent containing no sulfur atom non-sulfur chain transfer agent
  • non-sulfur chain transfer agents include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenoids such as ⁇ -pinene and terpinolene; ⁇ -methylstyrene, ⁇ -methylstyrene dimer, etc.
  • a chain transfer agent can be used individually by 1 type or in combination of 2 or more types.
  • the amount used can be, for example, about 0.01 to 1 part by weight per 100 parts by weight of the monomer component.
  • the weight average molecular weight (Mw) of the acrylic polymer is not particularly limited. It can be more than that. By using an acrylic polymer having a Mw of a predetermined value or more, it is easy to obtain an appropriate cohesive force capable of exhibiting desired adhesive properties. In addition, more additives such as plasticizers can be contained, and there is a tendency to easily achieve a desired elastic modulus. Further, the upper limit of the Mw of the acrylic polymer is, for example, about 500 ⁇ 10 4 or less, and from the viewpoint of adhesion performance, about 400 ⁇ 10 4 or less (more preferably about 150 ⁇ 10 4 or less, for example about 130 ⁇ 10 4 or less ). below).
  • the Mw of the acrylic polymer can be determined by gel permeation chromatography (GPC) in terms of polystyrene. Specifically, it can be obtained by measuring under the following conditions using a GPC measurement device with the trade name "HLC-8220GPC” (manufactured by Tosoh Corporation).
  • the adhesive composition disclosed herein is characterized by containing a plasticizer in addition to the acrylic polymer.
  • a plasticizer can reduce the elastic modulus of the adhesive.
  • a plasticizer can be used individually by 1 type or in combination of 2 or more types.
  • Non-limiting examples of compounds that can be options for plasticizers include compounds that can be used as the monomer (A1) (e.g., (meth)acrylates having aromatic rings such as benzyl groups, phenoxy groups, and naphthyl groups, and fluorene structures). a monomer having a dinaphthothiophene structure, a monomer having a dibenzothiophene structure, etc.); a compound containing the monomer (A1) as a monomer unit; Except for, a compound having a structure replaced with a group that does not have a hydrogen atom or an ethylenically unsaturated group (eg, 3-phenoxybenzyl alcohol); and the like.
  • the compound containing the monomer (A1) as a monomer unit may be copolymerized with a low Tg monomer such as n-butyl acrylate or 2-ethylhexyl acrylate from the viewpoint of improving flexibility.
  • Suitable examples of the plasticizer disclosed herein include cyclic unsaturated organic compounds having two or more double bond-containing rings.
  • the plasticizer as the preferred example is, in other words, a compound having two or more double bond-containing rings in one molecule. Therefore, the plasticizer has at least a first double bond-containing ring and a second double bond-containing ring. Having two or more double bond-containing rings can contribute to lowering the elastic modulus of the pressure-sensitive adhesive without impairing or maintaining the refractive index of the pressure-sensitive adhesive.
  • the number of double bond-containing rings contained in the plasticizer is preferably 6 or less, may be 4 or less, or may be 3 or less, from the viewpoint of exhibiting a plasticizing effect.
  • the plasticizer used in the technology disclosed herein is preferably a compound that is liquid at 30°C.
  • the term “liquid” means exhibiting fluidity, and indicates a liquid as a substance state.
  • Such compounds include compounds having a melting point of 30° C. or less. Since the plasticizer is liquid at 30° C., the plasticizing effect is favorably exhibited, and the elastic modulus of the pressure-sensitive adhesive can be effectively reduced.
  • the plasticizer is preferably a compound that is liquid at 25°C, more preferably a compound that is liquid at 20°C. For example, by using a compound that has two or more double bond-containing rings and is liquid at 30° C. as the plasticizer, it is possible to preferably form a pressure-sensitive adhesive that has both a high refractive index and a low elastic modulus.
  • the double bond-containing ring of the plasticizer may be a conjugated double bond-containing ring (typically an aromatic ring) or a non-conjugated double bond-containing ring. Any double bond-containing ring may be used.
  • the plasticizer may have at least one ring selected from an aromatic ring and a heterocyclic ring (heterocyclic ring) as the double bond-containing ring.
  • the heterocyclic ring may have a structure included in an aromatic ring, or may have a double bond-containing heterocyclic structure different from the aromatic ring.
  • the double bond-containing ring (typically aromatic ring) that the plasticizer may have includes a benzene ring (which may be a benzene ring constituting part of a biphenyl structure or a fluorene structure); a naphthalene ring, an indene ring.
  • a benzene ring which may be a benzene ring constituting part of a biphenyl structure or a fluorene structure
  • a naphthalene ring an indene ring.
  • azulene ring, anthracene ring, condensed ring of phenanthrene ring may be a heterocyclic ring such as an oxazole ring, isoxazole ring, thiazole ring, thiophene ring;
  • the heteroatoms contained as ring-constituting atoms in the above heterocycle may be one or more selected from the group consisting of nitrogen, sulfur and oxygen, for example.
  • the heteroatoms that make up the heterocycle can be one or both of nitrogen and sulfur.
  • the plasticizer may have a structure in which one or more carbon rings and one or more heterocycles are condensed, such as a dinaphthothiophene structure.
  • the double bond-containing ring may have one or more substituents on the ring-constituting atoms, or may have no substituents. good.
  • the substituent includes an alkyl group, an alkoxy group, an aryloxy group, a hydroxyl group, a halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), a hydroxyalkyl group, a hydroxyalkyloxy group, and a glycidyloxy group. etc. are exemplified, but not limited to these.
  • the number of carbon atoms contained in the substituent is preferably 1-4, more preferably 1-3, and can be, for example, 1 or 2.
  • the double bond-containing ring has no substituents on the ring atoms, alkyl groups, alkoxy groups, ethylenically unsaturated groups (e.g., (meth)acryloxy groups), hydroxy groups and hydroxy It may be an aromatic ring having one or more substituents selected from the group consisting of alkyl groups. Alkyl groups, alkoxy groups, and hydroxyalkyl groups are preferably used as substituents.
  • a compound having no ethylenically unsaturated group can be preferably employed as a plasticizer.
  • a plasticizer that does not have an ethylenically unsaturated group means that, in a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the plasticizer, changes in elastic modulus, dimensional changes, and deformation ( It is also preferable from the viewpoint of suppressing the occurrence of warpage, waviness, etc.), optical distortion, and the like.
  • a high refractive index plasticizer having a refractive index of about 1.50 or more can be preferably used as the plasticizer.
  • the refractive index of the plasticizer is preferably about 1.51 or more, more preferably about 1.53 or more, and even more preferably about 1.55, from the viewpoint of maintaining and improving the refractive index of the pressure-sensitive adhesive while reducing the elastic modulus. It may be about 1.56 or more, about 1.58 or more, about 1.60 or more, or about 1.62 or more.
  • the refractive index of the plasticizer is suitably 2.50 or less, and 2.00 or less, from the viewpoint of ease of preparation of the pressure-sensitive adhesive composition, compatibility in the pressure-sensitive adhesive, and the like. and may be 1.90 or less, 1.80 or less, or 1.70 or less.
  • the refractive index of the plasticizer is measured using an Abbe refractometer under conditions of a measurement wavelength of 589 nm and a measurement temperature of 25° C. in the same manner as the refractive index of the monomer. If the manufacturer or the like provides the nominal value of the refractive index at 25° C., the nominal value can be adopted.
  • compounds that can be selected as the high refractive index plasticizer include diethylene glycol dibenzoate (refractive index 1.55), dipropylene glycol dibenzoate (refractive index 1.54), 3-phenoxytoluene (refractive index 1.57 ), 3-ethylbiphenyl (refractive index 1.59), 3-methoxybiphenyl (refractive index 1.61), 4-methoxybiphenyl (refractive index 1.57), polyethylene glycol dibenzoate, 3-phenoxybenzyl alcohol (refractive index 1.59), triphenyl phosphate (refractive index 1.56), benzyl benzoate (refractive index 1.57), 4-(tert-butyl)phenyldiphenyl phosphate (refractive index 1.56), trimethylphenyl phosphate ( refractive index 1.55), butyl benzyl phthalate (refractive index 1.54), rosin methyl ester (refractive index 1.53), alkylbenz
  • the molecular weight of the plasticizer is not particularly limited, those having a molecular weight smaller than that of the acrylic polymer are usually used.
  • the molecular weight of the plasticizer is suitably 30,000 or less, advantageously 25,000 or less, and may be less than 10,000 (e.g., less than 5,000), from the viewpoint of facilitating the expression of the plasticizing effect. It may be less than 3000.
  • the molecular weight of the plasticizer is preferably 2000 or less, more preferably 1200 or less, even more preferably 900 or less, may be 600 or less, may be 500 or less, may be 400 or less, may be 300 It may be less than or equal to 250 or less (for example, 220 or less).
  • the molecular weight of the plasticizer is suitably 100 or more, preferably 130 or more, more preferably 150 or more, more preferably 170 or more, from the viewpoint of easily exhibiting a sufficient plasticizing effect. , 200 or more, 220 or more, or 250 or more. It is preferable that the molecular weight of the plasticizer is not too low from the viewpoint of the heat resistance of the pressure-sensitive adhesive sheet and the suppression of contamination of the adherend.
  • the molecular weight of the plasticizer a molecular weight calculated based on the chemical structure is used. When the nominal value of the molecular weight is provided by the manufacturer or the like, the nominal value can be adopted.
  • a plasticizer a compound having a structure in which two or more non-condensed double bond-containing rings (typically aromatic rings) are linked via a linking group, two or more non-condensed double bond-containing Compounds having a structure in which rings (typically aromatic rings) are directly (that is, not through other atoms) chemically bonded, compounds having a condensed double bond-containing ring (typically aromatic ring) structure, fluorene a compound having a structure, a compound having a dinaphthothiophene structure, a compound having a dibenzothiophene structure, etc., and being liquid at 30°C (e.g., 25°C or 20°C). Any of the above may be used.
  • the linking group is, for example, an oxy group (—O—), a thiooxy group (—S —), an oxyalkylene group (eg —O—(CH 2 ) n — group, where n is 1 to 3, preferably 1), a thiooxyalkylene group (eg —S—(CH 2 ) n — group, where where n is 1 to 3, preferably 1), a linear alkylene group (that is, —(CH 2 ) n — group, where n is 1 to 6, preferably 1 to 3), the above oxyalkylene group, the above thiooxy
  • the alkylene group and the alkylene group in the linear alkylene group may be a partially halogenated group or a fully halogenated group.
  • the linking group may have an ester bond.
  • the linking group that connects the first double bond-containing ring (non-fused ring) and the second double bond-containing ring (non-fused ring) may also be selected from the same types as above.
  • preferred examples of the linking group include an oxy group, a thiooxy group, an oxyalkylene group and a linear alkylene group.
  • the number of atoms of the linking group is not particularly limited, and is, for example, 1 to 30, may be 1 to 25, may be 1 to 20, is suitably 1 to 18, preferably 1 to 12, more preferably 1 to 10, more preferably 1 to 8, particularly preferably 1 to 5, may be 1 to 3, or may be 1 or 2.
  • the number of atoms in the linking group refers to the minimum number of atoms required to reach from one non-condensed double bond-containing ring to the other non-condensed double bond-containing ring.
  • the linking group consists of a linear alkylene group (ie, -(CH 2 ) n - group)
  • the number n is the number of atoms in the linking group.
  • the linking group is an oxyethylene group (that is, —(C 2 H 4 O) n — group)
  • the sum of 2 carbon atoms and 1 oxygen atom constituting the oxyethylene group is 3 and n
  • the product (3n) of is the number of atoms of the linking group.
  • the above compounds include compounds having a phenoxybenzyl group. Examples of such compounds include phenoxybenzyl (meth)acrylate (e.g. m-phenoxybenzyl (meth)acrylate), phenoxybenzyl alcohol, oxybis[(alkoxyalkyl)benzene] (e.g. 4,4′-oxybis[(methoxy methyl)benzene]) and the like.
  • a compound having a structure in which two or more double bond-containing rings (non-condensed rings) are directly chemically bonded may be, for example, a biphenyl structure-containing compound, a triphenyl structure-containing compound, or the like.
  • Examples of compounds having a condensed double bond-containing ring structure include naphthalene ring-containing compounds and anthracene ring-containing compounds. Specific examples include 1-acetonaphthone and the like.
  • the compound having the fluorene structure includes a structural portion in which two benzene rings are directly chemically bonded, the concept of a compound having a structure in which the two or more double bond-containing rings (non-condensed rings) are directly chemically bonded.
  • the compound having the dinaphthothiophene structure is based on the concept of the compound having the condensed double bond-containing ring structure by including a naphthalene structure and by having a structure in which a thiophene ring and two naphthalene structures are condensed. subsumed. Since the compound having the dibenzothiophene structure has a structure in which a thiophene ring and two benzene rings are condensed, it is included in the concept of the compound having the condensed double bond-containing ring structure.
  • an ethylene glycol-based compound having two or more double bond-containing rings in one molecule can be used as a plasticizer.
  • the number of oxyethylene units (that is, —(C 2 H 4 O)—units) possessed by the ethylene glycol compound is, for example, 1 to 10, may be 1 to 6, or may be 2 to 4.
  • two or more non-condensed double bond-containing rings have oxyethylene units (for example, 1 to 10, preferably 1 to 6, further 2 to 4 oxyethylene units) as linking groups. It can be a compound having a structure connected via. Such compounds may have one or more ester groups.
  • Examples of the ethylene glycol-based compound include compounds having a structure in which two or more benzoic acids are linked to ethylene glycol, diethylene glycol, triethylene glycol or polyethylene glycol via an ester bond.
  • the technology disclosed herein can be practiced in a mode in which the ethylene glycol compound is not used as a plasticizer, or the amount used is limited.
  • the content of the ethylene glycol-based compound in the plasticizer contained in the adhesive can be less than 90% by weight.
  • the content of the ethylene glycol-based compound in the plasticizer may be less than 50% by weight, less than 10% by weight, less than 3% by weight, or less than 1% by weight.
  • the agent may not substantially contain the ethylene glycol-based compound.
  • the amount of the ethylene glycol-based compound used relative to 100 parts by weight of the base polymer for example, an acrylic polymer
  • the amount of the ethylene glycol-based compound used relative to 100 parts by weight of the base polymer can be less than 0.5 parts by weight, even if it is less than 0.1 parts by weight. good.
  • liquid rosins such as liquid rosin esters and liquid camphenphenol can be used as plasticizers.
  • the above-mentioned liquid rosins (for example, liquid rosin esters) can correspond to compounds having the above-mentioned condensed double bond-containing ring structure.
  • plasticizer one or more of known plasticizers (e.g., phthalate-based, terephthalate-based, adipate-based, adipic acid-based polyester, benzoic acid glycol ester, etc.) may be used. good too.
  • plasticizers e.g., phthalate-based, terephthalate-based, adipate-based, adipic acid-based polyester, benzoic acid glycol ester, etc.
  • the amount of plasticizer used is not particularly limited and can be set according to the purpose. From the viewpoint of reducing the elastic modulus of the pressure-sensitive adhesive, the amount of the plasticizer used relative to 100 parts by weight of the acrylic polymer may be, for example, 1 part by weight or more, or may be 10 parts by weight or more. In some preferred embodiments, the amount of the plasticizer used relative to 100 parts by weight of the acrylic polymer is more than 15 parts by weight, may be 20 parts by weight or more, or may be 30 parts by weight or more (for example, more than 30 parts by weight). More preferably 40 parts by weight or more, more preferably 50 parts by weight or more, particularly preferably 60 parts by weight or more, may be 75 parts by weight or more, or may be 90 parts by weight or more.
  • the amount of the plasticizer used relative to 100 parts by weight of the acrylic polymer is appropriately set to about 200 parts by weight or less. It is preferably 150 parts by weight or less, more preferably 120 parts by weight or less, may be 100 parts by weight or less, may be 80 parts by weight or less, or may be 70 parts by weight or less. In some aspects in which adhesive properties are emphasized more, the amount of the plasticizer used with respect to 100 parts by weight of the acrylic polymer may be 45 parts by weight or less, or may be 35 parts by weight or less.
  • the adhesive compositions disclosed herein contain oligomers. Adhesion can be improved by including an oligomer in the pressure-sensitive adhesive composition.
  • the oligomer one having an appropriate molecular weight is used so as to exhibit the desired adhesive strength.
  • the weight-average molecular weight (Mw) of the oligomer is, for example, about 1000 or more, preferably about 3000 or more, more preferably about 4000 or more, and may be about 5000 or more. It may be 6000 or more, or 7000 or more. In some preferred embodiments, the Mw is 8,000 or more, may be 10,000 or more, or may be 15,000 or more.
  • the upper limit of the Mw of the oligomer is, for example, less than 50,000.
  • the Mw of the oligomer is less than 10,000, may be 8,500 or less, may be 7,500 or less, may be 6,500 or less, may be 5,500 or less.
  • the above oligomers having the above Mw can be used singly or in combination of two or more.
  • the above oligomer may be referred to as an adhesive force-improving oligomer for the purpose of distinguishing it from oligomers used for other purposes.
  • the Mw of the oligomer can be measured by GPC and obtained as a value converted to standard polystyrene. Specifically, it is measured using TSKgelGMH-H (20) ⁇ 2 columns in Tosoh's product name "HPLC8020" under the conditions of a flow rate of about 0.5 mL/min with tetrahydrofuran solvent. Alternatively, if a manufacturer or the like provides a nominal value for Mw, that nominal value can be adopted.
  • the glass transition temperature (Tg) of the oligomer is not limited to a specific range, and an appropriate Tg is used in consideration of adhesive strength and the like.
  • the Tg of the oligomer can be about 0°C or higher, suitably about 20°C or higher, preferably about 40°C or higher, more preferably about 50°C or higher, and even about 70°C or higher. Well, it may be about 90° C. or higher, or about 120° C. or higher.
  • the Tg can be, for example, approximately 200° C. or lower, suitably approximately 150° C. or lower, preferably approximately 140° C. or lower, may be approximately 125° C. or lower, or approximately 100° C. or lower. It may be about 80° C. or lower, or 60° C. or lower.
  • the Tg of an oligomer refers to the glass transition temperature (Tg ,DSC ) determined by differential scanning calorimetry (DSC measurement). Specifically, a sample (oligomer to be measured) sealed in an aluminum sample pan and a reference are prepared, and a differential scanning calorimeter (for example, trade name "Q2000" manufactured by TA Instruments) is used to determine a predetermined temperature. DSC measurement is performed in the range to create a calorific value curve, the temperature of the inflection point in the obtained calorific value curve is obtained, and this is taken as Tg , DSC [°C] of the oligomer.
  • Tg , DSC glass transition temperature
  • the rate of temperature increase and temperature decrease during the above measurement is 10 ° C./min, and the temperature range of ⁇ 70 ° C. of the baseline shift derived from Tg , DSC or a wider temperature range.
  • DSC measurements are performed with a minimum of 3 cycles of heating and cooling. In the temperature rising process of each cycle, the temperature at the midpoint between the inflection point on the low temperature side and the inflection point on the high temperature side of the baseline shift is determined, and Tg ,DSC [°C] in that cycle is determined. The average value of Tg ,DSC [°C] in the 2nd and 3rd cycles is used as the Tg ,DSC [°C] of the oligomer to be measured.
  • the (meth)acrylic oligomer is an acrylic monomer (including both an acrylic monomer having an acryloyl group and a methacrylic monomer having a methacryloyl group) as a main monomer unit ((meth)acrylic oligomer). It refers to an oligomer contained as a main component in the monomer components that form the monomer component, typically containing more than 50% by weight of monomer units.
  • the styrene-based oligomer refers to an oligomer containing a styrene-based monomer (a monomer having a styrene skeleton such as styrene and ⁇ -methylstyrene) as a monomer unit, and may be, for example, an oligomer containing the above styrene-based monomer as a main monomer unit.
  • a (meth)acrylic oligomer or a styrene oligomer to the acrylic polymer as the oligomer, it is possible to improve the adhesive force while maintaining a high refractive index and a low elastic modulus.
  • the (meth)acrylic oligomer is not particularly limited, and for example, those containing the following monomers as monomer units can be used.
  • Monomers constituting the (meth)acrylic oligomer include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl ( Alkyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, ison
  • the (meth)acrylic oligomer contains one or more selected from alkyl (meth)acrylates and alicyclic hydrocarbon group-containing (meth)acrylates as monomer units. , is preferable from the viewpoint of improving the adhesive strength.
  • methacrylic oligomers containing, as monomer units, one or more selected from alkyl methacrylates and alicyclic hydrocarbon group-containing methacrylates are preferably used.
  • alkyl (meth)acrylates that can be used include linear alkyl (meth)acrylates in which the alkyl group has 1 to 3 (preferably 1 or 2) carbon atoms.
  • Monomers having a saturated hydrocarbon group at the ester end are also preferable in that they are less likely to inhibit polymerization during the synthesis of oligomers.
  • the ratio of the (meth)acrylate monomer to the total monomer components constituting the (meth)acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, more preferably 70% by weight or more (for example, 80% by weight or more, further 90% by weight or more).
  • the (meth)acrylic oligomer may have a monomer composition consisting essentially of one or more (meth)acrylate monomers.
  • the upper limit of the ratio of the (meth)acrylate monomer to the total monomer components constituting the (meth)acrylic oligomer is 100% by weight, and in some embodiments, it may be 95% by weight or less, or 85% by weight or less. It's okay.
  • the ratio (copolymerization ratio) of the (meth)acrylate monomer can be employed.
  • functional group-containing monomers can be used as necessary as the constituent monomer components of the (meth)acrylic oligomer in addition to the (meth)acrylate monomers described above.
  • functional group-containing monomers include monomers having a nitrogen atom-containing heterocyclic ring such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; amino group-containing monomers such as N,N-dimethylaminoethyl (meth)acrylate; amide group-containing monomers such as N-diethyl(meth)acrylamide; carboxy group-containing monomers such as acrylic acid and methacrylic acid; hydroxyl group-containing monomers such as 2-hydroxyethyl(meth)acrylate; These functional group-containing monomers can be used singly or in combination of two or more.
  • carboxy group-containing monomers are preferably used.
  • carboxy group-containing monomers are preferably used.
  • a (meth)acrylic oligomer having a carboxy group is used for an acrylic polymer having a carboxy group, the effect of addition of the oligomer tends to be exhibited favorably.
  • the ratio of the functional group-containing monomer to the total monomer components constituting the (meth)acrylic oligomer is, for example, 1% by weight or more, and the effect of using the functional group-containing monomer is effectively obtained. From a viewpoint, it may be 5% by weight or more, 8% by weight or more, 12% by weight or more, or 16% by weight or more. Further, from the viewpoint of maintaining the effect of the (meth)acrylate monomer which is the main monomer unit, the ratio of the functional group-containing monomer to the total monomer components constituting the (meth)acrylic oligomer is, for example, 40% by weight or less. 25% by weight or less, 15% by weight or less, 10% by weight or less, or 3% by weight or less.
  • the (meth)acrylic oligomer may be one in which no functional group-containing monomer is used.
  • preferred examples of (meth)acrylic oligomers include isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), cyclohexyl methacrylate (CHMA), methyl methacrylate (MMA), benzyl methacrylate ( BZMA), copolymers of CHMA and MMA, copolymers of CHMA and ethyl methacrylate (EMA), copolymers of CHMA and isobutyl methacrylate (i-BMA), CHMA and IBXMA a copolymer of CHMA and dicyclopentanyl methacrylate (DCPMA), a copolymer of CHMA and dicyclopentenyloxyethyl methacrylate (DCP(EO)MA), CHMA and methacrylic acid (MAA), copolymers of MMA and MAA, and the like.
  • IBXMA isobornyl methacrylate
  • IBXA isobornyl acryl
  • Styrene-based oligomers include, for example, styrene-acrylic oligomers and styrene-maleic acid oligomers. These can be copolymers of styrene with other monomers such as (meth)acrylic acid and maleic acid. Styrenic oligomers can be used singly or in combination of two or more.
  • the acid value of the oligomer is not particularly limited, and is about 10 mgKOH/g or more (for example, about 30 mgKOH/g or more, preferably about 50 mgKOH/g or more or 70 mgKOH/g or more). It is preferably used.
  • the upper limit of the acid value may be about 500 mgKOH/g or less (eg about 200 mgKOH/g or less, preferably about 100 mgKOH/g or less).
  • the acid number of the oligomer can be greater than 100 mg KOH/g and can be greater than or equal to 150 mg KOH/g.
  • the oligomer having the above acid value include a carboxy group-containing (meth)acrylic oligomer and a carboxy group-containing styrenic oligomer.
  • the acid value can be adjusted by adjusting the amount of carboxyl groups introduced into the oligomer.
  • a value measured by the potentiometric titration method specified in JIS K0070:1992 can be adopted.
  • An oligomer for example, a (meth)acrylic oligomer
  • the polymerization method and polymerization mode are not particularly limited, and conventionally known various polymerization methods (eg, solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization, etc.) can be employed in an appropriate mode.
  • the oligomer is produced by radical polymerization
  • the polymerization can be carried out by appropriately adding a polymerization initiator, a chain transfer agent, an emulsifier, etc. used for radical polymerization to the monomer component.
  • the polymerization initiator, chain transfer agent, emulsifier and the like used in the radical polymerization are not particularly limited and can be appropriately selected and used.
  • the Mw of the oligomer can be controlled by adjusting the amount of the polymerization initiator and the chain transfer agent used and the reaction conditions, and the amount used is appropriately adjusted according to these types.
  • the type and amount of polymerization initiator that can be used and the type of chain transfer agent are not particularly limited, but can be generally the same as those exemplified for the synthesis of the acrylic polymer.
  • the amount of the chain transfer agent used can be set according to the composition of the monomer components used in the synthesis of the oligomer, the type of the chain transfer agent, etc.
  • the amount of the chain transfer agent used for 100 parts by weight of the monomer component used for the synthesis of the oligomer is suitably about 15 parts by weight or less, may be 10 parts by weight or less, and may be about 5 parts by weight. It can be below.
  • the lower limit of the amount of the chain transfer agent used relative to 100 parts by weight of the monomer component used for the synthesis of the oligomer is not particularly limited. It may be 1 part by weight or more, 1.5 parts by weight or more, 2 parts by weight or more, 2.5 parts by weight or more, or 3 parts by weight or more.
  • (Meth)acrylic oligomers include, for example, "ARUFON UC-3000 Series” available from Toagosei Co., Ltd., and trade names “VS-1028” and “RS-1190” available from Seiko PMC. mentioned.
  • Examples of styrene-based oligomers include trade name "X-200” and trade name "US-1071” manufactured by Seiko PMC.
  • the content of the oligomer in the adhesive composition disclosed here is not particularly limited. From the viewpoint of obtaining the effect of improving the adhesive strength by adding the oligomer, the content of the oligomer is appropriately 1 part by weight or more, preferably 2 parts by weight or more, more preferably 3 parts by weight, based on 100 parts by weight of the acrylic polymer. It is at least 5 parts by weight, preferably at least 5 parts by weight, and may be at least 8 parts by weight. From the viewpoint of maintaining a high refractive index and a low elastic modulus, the content of the oligomer with respect to 100 parts by weight of the acrylic polymer is, for example, 30 parts by weight or less, preferably 20 parts by weight or less. It may be not more than 10 parts by weight, or not more than 7 parts by weight. By appropriately limiting the amount of the oligomer used, it is possible to improve adhesive properties such as adhesive strength while maintaining a high refractive index and a low elastic modulus.
  • the pressure-sensitive adhesive composition disclosed herein may optionally contain an organic material having a higher refractive index than the acrylic polymer as an additive.
  • an organic material may be referred to as an "additive (H RO )".
  • H RO represents an organic material with a high refractive index (High Refractive index).
  • the additive (H RO ) is defined as different from the compound used as the plasticizer described above.
  • the additive (H RO ) may specifically be one that is not liquid (liquid) at 30° C. (eg 25° C. or 20° C.).
  • Additives (H RO ) can be used singly or in combination of two or more.
  • the refractive index of the additive (H RO ) is not limited to a specific range because it can be set within an appropriate range in relation to the refractive index of the acrylic polymer.
  • the refractive index of the additive (H RO ) can be selected, for example, from a range greater than 1.55, greater than 1.56 or greater than 1.57 and higher than the refractive index of the acrylic polymer.
  • the refractive index of the additive (H RO ) is advantageously 1.58 or more, preferably 1.60 or more, It is more preferably 1.63 or more, may be 1.65 or more, may be 1.70 or more, or may be 1.75 or more.
  • the upper limit of the refractive index of the additive (H RO ) is not particularly limited. 000 or less, 2.500 or less, 2.000 or less, 1.950 or less, 1.900 or less, or 1.850 or less.
  • the refractive index of the additive (H RO ) is measured using an Abbe refractometer under conditions of a measurement wavelength of 589 nm and a measurement temperature of 25° C. in the same manner as the refractive index of the monomer. If the manufacturer or the like provides the nominal value of the refractive index at 25° C., the nominal value can be adopted.
  • ⁇ n A The difference between the refractive index n b of the additive (H RO ) and the refractive index na of the acrylic polymer, that is, n b ⁇ na (hereinafter also referred to as “ ⁇ n A ”) is set to be greater than 0. be done.
  • ⁇ n A is, for example, 0.02 or greater, 0.05 or greater, 0.07 or greater, 0.10 or greater, 0.15 or greater, 0.20 or greater. Alternatively, it may be 0.25 or more.
  • ⁇ n A may be, for example, 0.70 or less, 0.60 or less, or 0.50 or less. 0.40 or less, or 0.35 or less.
  • the difference between the refractive index n b of the additive (H RO ) and the refractive index n T of the adhesive containing the additive (H RO ), i.e., n b ⁇ n T may be set to be greater than zero.
  • ⁇ n B is, for example, 0.02 or greater, 0.05 or greater, 0.07 or greater, 0.10 or greater, 0.15 or greater, 0.20 or greater. Alternatively, it may be 0.25 or more.
  • ⁇ n B may be, for example, 0.70 or less, 0.60 or less, or 0.50 It may be less than or equal to 0.40 or less or 0.35 or less.
  • the molecular weight of the organic material used as the additive (H RO ) is not particularly limited and can be selected depending on the purpose. From the viewpoint of achieving a good balance between the effect of increasing the refractive index and other properties (e.g., flexibility suitable for adhesives, optical properties such as haze), in some embodiments, the molecular weight of the additive (H RO ) is suitably less than about 10000, preferably less than 5000, more preferably less than 3000 (e.g. less than 1000), may be less than 800, may be less than 600, may be less than 500, It may be less than 400. It can be advantageous from the viewpoint of improving the compatibility in the adhesive that the molecular weight of the additive (H RO ) is not too large.
  • the molecular weight of the additive (H RO ) may be, for example, 130 or more, or 150 or more.
  • the molecular weight of the additive (H RO ) is preferably 170 or more, more preferably 200 or more, more preferably 230, from the viewpoint of increasing the refractive index of the additive (H RO ). 250 or more, 270 or more, 500 or more, 1000 or more, or 2000 or more.
  • a polymer with a molecular weight of about 1000 to 10000 eg, 1000 or more and less than 5000 can be used as the additive (H RO ).
  • the molecular weight of the additive (H RO ) for a non-polymer or a polymer with a low degree of polymerization (for example, about 2- to 5-mers), the molecular weight calculated based on the chemical structure, or the matrix-assisted laser desorption/ionization Measurements using time-of-flight mass spectrometry (MALDI-TOF-MS) can be used. If the additive (H RO ) is a polymer with a higher degree of polymerization, the weight average molecular weight (Mw) based on GPC performed under appropriate conditions can be used. When the nominal value of the molecular weight is provided by the manufacturer or the like, the nominal value can be adopted.
  • organic materials that can be selected as the additive (H RO ) include organic compounds having an aromatic ring, organic compounds having a heterocyclic ring (which may be an aromatic ring or a non-aromatic heterocyclic ring), and the like. including but not limited to:
  • aromatic ring of the organic compound having an aromatic ring (hereinafter also referred to as "aromatic ring-containing compound") used as the additive (H RO ) is the same as the aromatic ring of the compound used as the monomer (A1).
  • aromatic ring-containing compound used as the additive (H RO ) is the same as the aromatic ring of the compound used as the monomer (A1).
  • the aromatic ring may or may not have one or more substituents on the ring-constituting atoms.
  • the substituent includes an alkyl group, an alkoxy group, an aryloxy group, a hydroxyl group, a halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), a hydroxyalkyl group, a hydroxyalkyloxy group, and a glycidyloxy group. etc. are exemplified, but not limited to these.
  • the number of carbon atoms contained in the substituent is, for example, 1 to 10, preferably 1 to 6, preferably 1 to 4, more preferably 1 to 3.
  • the aromatic ring has no substituents on ring-constituting atoms, or has one or more substituents selected from the group consisting of alkyl groups, alkoxy groups and halogen atoms (e.g., bromine atoms).
  • halogen atoms e.g., bromine atoms
  • H RO aromatic ring-containing compounds that can be used as additives
  • examples of aromatic ring-containing compounds that can be used as additives include: compounds that can be used as monomers (A1); compounds that contain monomers (A1) as monomer units; compounds that can be used as monomers (A1) A hydrogen atom or an ethylenically unsaturated group, except for a group having an ethylenically unsaturated group (which may be a substituent bonded to a ring-constituting atom) or a portion constituting an ethylenically unsaturated group, from a compound (e.g., a hydroxyl group, an amino group, a halogen atom, an alkyl group, an alkoxy group, a hydroxyalkyl group, a hydroxyalkyloxy group, a glycidyloxy group, etc.) that does not have a structure substituted with a compound; Examples include, but are not limited to, those that do not fall under the plastic
  • an organic compound having two or more aromatic rings in one molecule (hereinafter referred to as "multiple aromatic ring-containing compound ”) can be preferably adopted.
  • the compound containing multiple aromatic rings may or may not have a polymerizable functional group such as an ethylenically unsaturated group.
  • the compound containing multiple aromatic rings may be a polymer or a non-polymer.
  • the polymer may be a compound containing a monomer containing multiple aromatic rings as a monomer unit (for example, a low polymer of about 2- to 5-mers).
  • Non-limiting examples of compounds containing multiple aromatic rings include compounds having a structure in which two or more non-fused aromatic rings are linked via a linking group, two or more non-fused aromatic rings directly (i.e., other atoms compounds having a chemically bonded structure, compounds having a condensed aromatic ring structure, compounds having a fluorene structure, compounds having a dinaphthothiophene structure, compounds having a dibenzothiophene structure, and the like.
  • the compounds containing multiple aromatic rings may be used singly or in combination of two or more.
  • Examples of organic compounds having a heterocyclic ring that can be options for the additive (H RO ) include thioepoxy compounds, compounds having a triazine ring, and the like.
  • Examples of thioepoxy compounds include bis(2,3-epithiopropyl)disulfide and its polymer (refractive index 1.74) described in Japanese Patent No. 3712653.
  • Examples of compounds having a triazine ring include compounds having at least one (eg, 3 to 40, preferably 5 to 20) triazine rings in one molecule.
  • triazine ring has aromaticity
  • compounds having a triazine ring are also included in the concept of compounds containing a triazine ring, and compounds having a plurality of triazine rings are also included in the concept of compounds containing multiple aromatic rings. be done.
  • a compound having no ethylenically unsaturated groups can be preferably employed as the additive (H RO ).
  • H RO the additive
  • deterioration of the pressure-sensitive adhesive composition due to heat or light decrease in leveling properties due to progression of gelation or increase in viscosity
  • Employing an additive (H RO ) that does not have an ethylenically unsaturated group prevents a dimensional change due to reaction of the ethylenically unsaturated group in a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the additive (H RO ). It is also preferable from the viewpoint of suppressing deformation (warpage, waviness, etc.), generation of optical distortion, and the like.
  • the amount of the additive (H RO ) used relative to 100 parts by weight of the acrylic polymer is not particularly limited as long as it exceeds 0 parts by weight, and is set according to the purpose. can do.
  • the amount of the additive (H RO ) used relative to 100 parts by weight of the acrylic polymer can be, for example, 80 parts by weight or less, which increases the refractive index of the adhesive and reduces the adhesive properties and optical properties. From the viewpoint of achieving both suppression and suppression in a well-balanced manner, it is advantageous to set the content to 60 parts by weight or less, preferably 45 parts by weight or less.
  • the amount of the additive (H RO ) used relative to 100 parts by weight of the acrylic polymer may be, for example, 30 parts by weight or less, or may be 20 parts by weight or less. It may be 15 parts by weight or less, or may be 10 parts by weight or less.
  • the amount of the additive (H RO ) used relative to 100 parts by weight of the acrylic polymer may be, for example, 1 part by weight or more, and may be 3 parts by weight or more.
  • the pressure-sensitive adhesive composition disclosed herein may contain a cross-linking agent, if necessary, for the purpose of adjusting the cohesive strength of the pressure-sensitive adhesive.
  • a cross-linking agent known in the field of adhesives such as an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an aziridine-based cross-linking agent, an oxazoline-based cross-linking agent, a melamine-based resin, a metal chelate-based cross-linking agent, etc. can be used. can be done. Among them, isocyanate-based cross-linking agents and epoxy-based cross-linking agents can be preferably employed.
  • Other examples of cross-linking agents include monomers having two or more ethylenically unsaturated groups in one molecule, ie, polyfunctional monomers.
  • a crosslinking agent can be used individually by 1 type or in combination of 2 or more types.
  • an isocyanate compound having a functionality of 2 or more can be used.
  • Examples of commercially available products include Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (manufactured by Takeda Pharmaceutical Co., Ltd.), Sumidule T80, Sumidule L, and Desmodur N3400 (manufactured by Sumika Bayer Co., Ltd.). Urethane Corporation), Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (all manufactured by Tosoh Corporation), and the like.
  • An isocyanate compound can be used individually by 1 type or in combination of 2 or more types.
  • a bifunctional isocyanate compound and a trifunctional or higher isocyanate compound may be used in combination.
  • Epoxy cross-linking agents include, for example, bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylol.
  • Propane triglycidyl ether, diglycidylaniline, diamine glycidylamine, N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, etc. can be mentioned. These can be used individually by 1 type or in combination of 2 or more types.
  • polyfunctional monomers include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, Pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecane Diol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, bisphenol A di(meth)acrylate, epoxy acrylate , polyester
  • the amount of the cross-linking agent used is not particularly limited, and can be, for example, in the range of about 0.001 to 5.0 parts by weight with respect to 100 parts by weight of the acrylic polymer. From the viewpoint of improving the adhesion to the adherend, in some embodiments, the amount of the cross-linking agent used is preferably 3.0 parts by weight or less, more preferably 2.0 parts by weight or less with respect to 100 parts by weight of the acrylic polymer. Yes, it may be 1.0 parts by weight or less, 0.5 parts by weight or less, or 0.2 parts by weight or less.
  • the amount of the cross-linking agent used relative to 100 parts by weight of the acrylic polymer may be, for example, 0.005 parts by weight or more, and may be 0.01 part by weight or more. It may be 0.05 parts by weight or more, 0.08 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, or 0.4 parts by weight. It can be more than that.
  • a cross-linking catalyst may be used to promote the cross-linking reaction more effectively.
  • cross-linking catalysts include metallic cross-linking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, Nasem ferric, butyltin oxide, and dioctyltin dilaurate. Of these, tin-based cross-linking catalysts such as dioctyltin dilaurate are preferred.
  • the amount of cross-linking catalyst used is not particularly limited.
  • the amount of the cross-linking catalyst used with respect to 100 parts by weight of the acrylic polymer is, for example, about 0.0001 part by weight or more and 1 part by weight or less in consideration of the balance between the speed of the crosslinking reaction rate and the length of the pot life of the pressure-sensitive adhesive composition. It can be in the range of 0.001 parts by weight or more and 0.5 parts by weight or less.
  • the adhesive composition can contain a compound that causes keto-enol tautomerism as a cross-linking retarder. This can achieve the effect of extending the pot life of the pressure-sensitive adhesive composition.
  • a compound that exhibits keto-enol tautomerism can be preferably used in a pressure-sensitive adhesive composition containing an isocyanate-based cross-linking agent.
  • Various ⁇ -dicarbonyl compounds can be used as compounds that cause keto-enol tautomerism.
  • ⁇ -diketones acetylacetone, 2,4-hexanedione, etc.
  • acetoacetic esters methyl acetoacetate, ethyl acetoacetate, etc.
  • the compounds that cause keto-enol tautomerism can be used singly or in combination of two or more.
  • the amount of the compound that causes keto-enol tautomerism can be, for example, 0.1 parts by weight or more and 20 parts by weight or less, and 0.5 parts by weight or more and 10 parts by weight, relative to 100 parts by weight of the acrylic polymer. or less, or 1 part by weight or more and 5 parts by weight or less.
  • Tackifier The adhesive composition disclosed herein may contain a tackifier.
  • Tackifiers include rosin-based tackifier resins, terpene-based tackifier resins, phenol-based tackifier resins, hydrocarbon-based tackifier resins, ketone-based tackifier resins, polyamide-based tackifier resins, epoxy-based tackifier resins, and elastomers.
  • Known tackifying resins can be used, such as system tackifying resins. These can be used individually by 1 type or in combination of 2 or more types.
  • the amount of the tackifying resin to be used is not particularly limited, and can be set so as to exhibit appropriate adhesive performance depending on the purpose and application.
  • the amount of the tackifier used relative to 100 parts by weight of the acrylic polymer is suitably 30 parts by weight or less, and may be 10 parts by weight or less. Preferably, it is 5 parts by weight or less.
  • the technology disclosed herein can be preferably practiced in a mode that does not use a tackifier.
  • the adhesive composition disclosed herein can contain high refractive index particles as an optional component.
  • the high refractive index particles mean particles capable of increasing the refractive index of the pressure-sensitive adhesive by being contained in the pressure-sensitive adhesive.
  • the high refractive index particles may be referred to as "particles P HRI ".
  • HRI stands for high refractive index.
  • the type of particles P HRI is not particularly limited, and one or more materials that can improve the refractive index of the adhesive are selected from metal particles, metal compound particles, organic particles, and organic-inorganic composite particles. can be selected and used.
  • inorganic oxides that can improve the refractive index of the pressure-sensitive adhesive sheet can be preferably used.
  • materials constituting the particles PHRI include titania (titanium oxide, TiO 2 ), zirconia (zirconium oxide, ZrO 2 ), aluminum oxide, zinc oxide, tin oxide, copper oxide, barium titanate, niobium oxide ( Nb 2 O 5 , etc.) and other inorganic oxides (specifically, metal oxides). Particles composed of these inorganic oxides (for example, metal oxides) can be used singly or in combination of two or more.
  • the average particle size of the particles PHRI (meaning the 50% volume average particle size based on the laser scattering/diffraction method) is not particularly limited, and can be selected, for example, from the range of about 1 nm to 1000 nm.
  • Particles PHRI in the adhesive composition can be used in an appropriate amount within a range that does not impair the effects of the technology disclosed herein.
  • the content of the particles PHRI can vary depending on the desired refractive index.
  • the content of the particles PHRI can be appropriately set in consideration of the required adhesion properties and the like so that the refractive index is equal to or greater than a predetermined value.
  • the content of particulate P HRI in the adhesive composition is, for example, less than 10% by weight, and may be less than 1% by weight, in the adhesive formed from the adhesive composition, It may be less than 0.1% by weight.
  • the techniques disclosed herein can be practiced in such a manner that the adhesive composition is substantially free of particulate PHRI .
  • the pressure-sensitive adhesive composition contains a , a leveling agent can be contained as necessary.
  • leveling agents include acrylic leveling agents, fluorine-based leveling agents, silicone-based leveling agents, and the like.
  • An appropriate leveling agent can be selected from, for example, commercially available leveling agents and used in a conventional manner.
  • the pressure-sensitive adhesive composition disclosed herein contains softening agents, coloring agents (dyes, pigments, etc.), fillers, antistatic agents, anti-aging agents, ultraviolet absorbing agents, as long as the effects of the present invention are not significantly hindered.
  • Known additives that can be used in pressure-sensitive adhesive compositions such as agents, antioxidants, light stabilizers, preservatives, etc., may optionally be included.
  • conventionally known ones can be used in a conventional manner, and since they do not particularly characterize the present invention, detailed description thereof will be omitted.
  • the adhesive disclosed herein can be formed using, for example, any of the adhesive compositions described above.
  • Such an adhesive is an adhesive obtained by curing an adhesive composition in the form of solvent type, active energy ray-curable type, water dispersion type, hot-melt type, etc. by drying, crosslinking, polymerization, cooling, etc., that is, the above-mentioned adhesive It may be a cured product of the agent composition.
  • the curing means for example, drying, crosslinking, polymerization, cooling, etc.
  • the composition can be dried (preferably further crosslinked) to form the adhesive.
  • the pressure-sensitive adhesive is typically formed by irradiating an active energy ray to promote a polymerization reaction and/or a cross-linking reaction.
  • an active energy ray to promote a polymerization reaction and/or a cross-linking reaction.
  • the refractive index of the pressure-sensitive adhesive formed from the pressure-sensitive adhesive composition disclosed herein is higher than that of conventional general acrylic pressure-sensitive adhesives.
  • a pressure-sensitive adhesive having a refractive index of, for example, 1.55 or more, a pressure-sensitive adhesive composition capable of forming the pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet containing the pressure-sensitive adhesive can be provided.
  • the refractive index of the adhesive may be 1.560 or more, or may be greater than 1.570.
  • the adhesive may have a refractive index of 1.575 or higher, 1.580 or higher, or 1.585 or higher.
  • a pressure-sensitive adhesive having such a refractive index can suitably suppress light reflection at the interface with an adherend in a mode of use in which it is attached to a material with a high refractive index.
  • a preferable upper limit of the refractive index of the pressure-sensitive adhesive is not limited to a specific range because it may vary depending on the refractive index of the adherend and the like. It may be 650 or less, 1.620 or less, or 1.600 or less.
  • the refractive index of the pressure-sensitive adhesive can be adjusted, for example, by the composition of the pressure-sensitive adhesive (for example, the composition of monomer components constituting the acrylic polymer). Specifically, by including an acrylic polymer with a high content of the monomer (A1) in the monomer component, a high refractive index plasticizer, and an additive (H RO ), a pressure-sensitive adhesive exhibiting a predetermined or higher refractive index is prepared. can do.
  • the composition of the pressure-sensitive adhesive for example, the composition of monomer components constituting the acrylic polymer.
  • the refractive index of the adhesive refers to the refractive index of the surface (adhesive surface) of the adhesive.
  • the refractive index of the pressure-sensitive adhesive can be measured using a commercially available refractive index measuring device (Abbe refractometer) under conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C.
  • Abbe refractometer for example, model "DR-M4" manufactured by ATAGO or its equivalent is used.
  • an adhesive layer made of an adhesive to be evaluated can be used.
  • the refractive index of the pressure-sensitive adhesive can be measured by the method described in Examples below.
  • the storage modulus G' (0° C.) of the adhesive at 0° C. may be, for example, less than 1.0 ⁇ 10 8 Pa and 5.0 ⁇ 10 7 It may be less than Pa, less than 1.0 ⁇ 10 7 Pa, or less than 5.0 ⁇ 10 6 Pa.
  • the pressure-sensitive adhesive having the storage elastic modulus G′ (0° C.) has appropriate flexibility in a temperature range from around 0° C. to above, and can adhere well to an adherend, for example.
  • the lower limit of the storage elastic modulus G′ (0° C.) is not particularly limited, and is, for example, 1.0 ⁇ 10 2 Pa or higher, and may be 1.0 ⁇ 10 3 Pa or higher.
  • the pressure-sensitive adhesive tends to have an appropriate cohesive force, for example, in the normal temperature to high temperature range.
  • the storage modulus G′ (0° C.) of the adhesive is 1.0 ⁇ 10 6 Pa or less, more preferably 5.0 ⁇ 10 5 Pa or less, and 2.0 ⁇ 10 5 Pa or less.
  • the storage modulus G' (0°C) is preferably 1.0 ⁇ 10 4 Pa or more, may be 2.0 ⁇ 10 4 Pa or more, or may be 4.0 ⁇ 10 4 Pa or more. Well, it may be 6.0 ⁇ 10 4 Pa or higher, or 1.0 ⁇ 10 5 Pa or higher.
  • a pressure-sensitive adhesive having a storage modulus G′ (0° C.) within the above range can be flexible enough to withstand repeated bending operations.
  • the storage modulus G′ (80° C.) at 80° C. of the pressure-sensitive adhesive disclosed herein is not particularly limited. It is less than 10 4 Pa, more preferably less than 3.0 ⁇ 10 4 Pa, may be less than 1.0 ⁇ 10 4 Pa, and may be 5.0 ⁇ 10 3 Pa or less.
  • the PSA having a limited storage elastic modulus G' (80°C) as described above has good flexibility in a high temperature range.
  • the lower limit of the storage modulus G′ (80° C.) is not particularly limited, and is, for example, 1.0 ⁇ 10 2 Pa or more, preferably 5.0 ⁇ 10 2 Pa or more, preferably 1.0 ⁇ 10 2 Pa or more.
  • a pressure-sensitive adhesive having the storage elastic modulus G′ (80° C.) has an appropriate cohesive force even in a high temperature range and tends to be excellent in heat resistance, which is preferable.
  • the storage modulus G′ ( ⁇ 10° C.) at ⁇ 10° C. of the pressure-sensitive adhesive disclosed herein is not particularly limited, and may be, for example, less than 1.0 ⁇ 10 9 Pa, or 1.0 ⁇ 10 8 5. It may be less than Pa, suitably less than 1.0 ⁇ 10 7 Pa, preferably 5.0 ⁇ 10 6 Pa or less, and may be 1.0 ⁇ 10 6 Pa or less. It may be 0 ⁇ 10 5 Pa or less, or 1.0 ⁇ 10 5 Pa or less.
  • a pressure-sensitive adhesive having a limited storage modulus G' (-10°C) as described above can have superior flexibility. For example, it can have good flexibility in a low temperature range and have flexibility to withstand repeated bending operations in a wide temperature range including a low temperature range.
  • the lower limit of the storage modulus G′ is not particularly limited, and is, for example, 1.0 ⁇ 10 2 Pa or more, preferably 1.0 ⁇ 10 3 Pa or more, preferably 5 0 ⁇ 10 3 Pa or more, more preferably 1.0 ⁇ 10 4 Pa or more, may be 5.0 ⁇ 10 4 Pa or more, may be 1.0 ⁇ 10 5 Pa or more, and may be 5.0 ⁇ 10 5 Pa or more may be used.
  • a pressure-sensitive adhesive having the storage elastic modulus G′ ( ⁇ 10° C.) can be flexible and have appropriate cohesive strength.
  • the storage modulus G′ ( ⁇ 20° C.) at ⁇ 20° C. of the pressure-sensitive adhesive disclosed herein is not particularly limited, and may be, for example, less than 1.0 ⁇ 10 10 Pa, or 1.0 ⁇ 10 9 It may be less than Pa, is suitably 5.0 ⁇ 10 8 Pa or less, may be 1.0 ⁇ 10 8 Pa or less, may be 5.0 ⁇ 10 7 Pa or less, or may be 1.0 ⁇ 10 8 Pa or less. It may be 10 7 Pa or less, 5.0 ⁇ 10 6 Pa or less, 1.0 ⁇ 10 6 Pa or less, or 5.0 ⁇ 10 5 Pa or less.
  • a pressure-sensitive adhesive having a limited storage modulus G' (-20°C) as described above can have particularly excellent flexibility.
  • the lower limit of the storage modulus G′ ( ⁇ 20° C.) is not particularly limited, and is, for example, 1.0 ⁇ 10 2 Pa or more, suitably 1.0 ⁇ 10 3 Pa or more, preferably 1 0 ⁇ 10 4 Pa or more, more preferably 1.0 ⁇ 10 5 Pa or more, may be 5.0 ⁇ 10 5 Pa or more, or 1.0 ⁇ 10 6 Pa or more.
  • a pressure-sensitive adhesive having the storage modulus G′ ( ⁇ 20° C.) can be flexible and have appropriate cohesive force.
  • the adhesive has a ratio of storage modulus G' (0° C.) at 0° C. to storage modulus G' (80° C.) at 80° C. (G'(0° C.)/G'(80° C. )) is in the range of 1-1000.
  • a pressure-sensitive adhesive that satisfies the above properties suppresses changes in elastic modulus in a wide temperature range from 0° C. to high temperatures, and thus tends to exhibit stable properties (flexibility, etc.) against temperature changes.
  • the ratio (G'(0°C)/G'(80°C)) is suitably 300 or less, preferably 100 or less, more preferably 50 or less, and may be 25 or less, or even 10 or less. Well, it can be 5 or less.
  • the lower limit of the ratio (G'(0°C)/G'(80°C)) may be, for example, 2 or more, or 3 or more.
  • the adhesive has a ratio of storage modulus G' (-10°C) at -10°C to storage modulus G' (80°C) at 80°C (G'(-10°C)/G' (80° C.)) is in the range of 1 to 1,000.
  • An adhesive that satisfies the above properties suppresses changes in elastic modulus over a wide temperature range from low to high, so it is easy to exhibit stable properties (flexibility, etc.) against temperature changes.
  • the ratio (G'(-10°C)/G'(80°C)) is suitably 300 or less, preferably 150 or less, more preferably 100 or less, and may be 50 or less, or 30 or less. , 20 or less, or 10 or less.
  • the lower limit of the ratio (G'(-10°C)/G'(80°C)) may be, for example, 2 or more, or 3 or more.
  • the adhesive has a ratio of storage modulus G' (-20°C) at -20°C to storage modulus G' (80°C) at 80°C (G'(-20°C)/G' (80° C.)) is in the range of 1-1500.
  • Adhesives that satisfy the above properties exhibit stable properties (flexibility, etc.) against temperature changes because changes in elastic modulus are suppressed in a wide temperature range from lower temperature ranges to higher temperature ranges. be able to.
  • the ratio (G'(-20°C)/G'(80°C)) may be 1000 or less, 500 or less, 300 or less, 150 or less, 100 or less, or 50 or less. or 30 or less.
  • the lower limit of the ratio (G'(-20°C)/G'(80°C)) may be, for example, 5 or more, 10 or more, 50 or more, or 100 or more.
  • the glass transition temperature (Tg) of the adhesive is not particularly limited, and can be set in consideration of flexibility in low temperature ranges and cohesion (heat resistance, etc.) in high temperature ranges.
  • the Tg of the adhesive is, for example, 30° C. or less, may be 15° C. or less, or may be 5° C. or less.
  • the Tg of the adhesive is 0° C. or lower, more preferably -5° C. or lower, still more preferably -10° C. or lower, and -15° C. or lower (e.g., -20° C. or lower) from the viewpoint of flexibility. ° C. or less).
  • the lower limit of the Tg of the adhesive is, for example, -50°C or higher, preferably -40°C or higher, and may be -30°C or higher.
  • a pressure-sensitive adhesive having the above Tg tends to provide an appropriate cohesive force.
  • the storage elastic modulus G′ and the glass transition temperature Tg of the adhesive at each temperature can be measured by the method described in Examples below, and each storage elastic modulus ratio can be calculated from the results. can.
  • Each storage modulus G′, each storage modulus ratio and glass transition temperature Tg of the pressure-sensitive adhesive are determined, for example, by selection of the composition of the monomer components constituting the acrylic polymer (for example, selection of the type and content of the monomer (A1) ), selection of the type and amount of plasticizer used, presence/absence of use of cross-linking agent, selection of type and amount used, presence/absence of use of additive, selection of type and amount used, and the like.
  • the adhesive constituting the adhesive layer may be an adhesive formed from any of the adhesive compositions disclosed herein (for example, a cured product of the adhesive composition).
  • the pressure-sensitive adhesive sheet may be a pressure-sensitive adhesive sheet with a substrate having the pressure-sensitive adhesive layer on one or both sides of a non-releasable substrate (supporting substrate), and the pressure-sensitive adhesive layer is held by a release liner. It may be a substrate-less pressure-sensitive adhesive sheet (that is, a pressure-sensitive adhesive sheet having no non-releasable substrate, typically a pressure-sensitive adhesive layer).
  • the concept of the adhesive sheet as used herein can include what is called an adhesive tape, an adhesive label, an adhesive film, and the like.
  • the pressure-sensitive adhesive sheet disclosed herein may be roll-shaped or sheet-shaped. Alternatively, it may be a pressure-sensitive adhesive sheet processed into various shapes.
  • Figures 1 and 2 show configuration examples of a double-sided adhesive type baseless adhesive sheet (baseless double-sided adhesive sheet).
  • the pressure-sensitive adhesive sheet 1 shown in FIG. 1 has a configuration in which both surfaces 21A and 21B of a substrate-less pressure-sensitive adhesive layer 21 are protected by release liners 31 and 32 whose release surfaces are at least on the pressure-sensitive adhesive layer side.
  • the adhesive sheet 2 shown in FIG. 2 has a configuration in which one surface (adhesive surface) 21A of a substrate-less adhesive layer 21 is protected by a release liner 31 having release surfaces on both sides. When wound, the other surface (adhesive surface) 21B of the adhesive layer 21 contacts the back surface of the release liner 31, so that the other surface 21B is also protected by the release liner 31.
  • the technology disclosed herein is preferably implemented in the form of a substrate-less pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer, from the viewpoint of flexibility to follow an adherend that is repeatedly bent.
  • the substrate-less pressure-sensitive adhesive sheet is preferable, for example, from the viewpoint of reducing the thickness of the pressure-sensitive adhesive sheet and from the viewpoint of increasing the transparency of the pressure-sensitive adhesive sheet.
  • the adhesive sheet disclosed here can have, for example, the cross-sectional structure schematically shown in FIG.
  • the pressure-sensitive adhesive sheet 3 shown in FIG. Prepare. Both the first surface 10A and the second surface 10B are non-peeling surfaces (non-peeling surfaces).
  • the adhesive sheet 3 is used by attaching the surface (first adhesive surface) 21A of the first adhesive layer 21 and the surface (second adhesive surface) 22A of the second adhesive layer 22 to an adherend. That is, the adhesive sheet 3 is configured as a double-sided adhesive sheet (double-sided adhesive adhesive sheet).
  • the pressure-sensitive adhesive sheet 3 before use has a first pressure-sensitive adhesive surface 21A and a second pressure-sensitive adhesive surface 22A protected by release liners 31 and 32, each of which has a peelable surface (release surface) on at least the pressure-sensitive adhesive surface side. have a configuration.
  • the release liner 32 may be omitted and a release liner 31 having release surfaces on both sides may be used. Therefore, the second adhesive surface 22A may also be protected by the release liner 31 .
  • the technique disclosed herein is preferably implemented in the form of the above-described baseless or base-attached double-sided pressure-sensitive adhesive sheet for fixing or joining members (for example, optical members).
  • the PSA sheet disclosed herein may be in the form of a substrate-attached single-sided PSA sheet having an adhesive layer only on one side of a non-releasable substrate (supporting substrate), although not shown.
  • the form of the single-sided pressure-sensitive adhesive sheet there is a form that does not have either the first pressure-sensitive adhesive layer 21 or the second pressure-sensitive adhesive layer 22 in the configuration shown in FIG.
  • the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein can be formed by applying (for example, applying) a pressure-sensitive adhesive composition to a suitable surface and then curing the composition.
  • Application of the pressure-sensitive adhesive composition can be carried out using a conventional coater such as gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, and spray coater.
  • the thickness of the adhesive layer is not particularly limited, and can be, for example, 3 ⁇ m or more. In some embodiments, the thickness of the pressure-sensitive adhesive layer is suitably, for example, 5 ⁇ m or more, and may be 10 ⁇ m or more, 15 ⁇ m or more, 20 ⁇ m or more, 30 ⁇ m or more, or 50 ⁇ m or more. or 70 ⁇ m or more or 85 ⁇ m or more.
  • the adhesive strength tends to increase as the thickness of the adhesive layer increases. In some aspects, the thickness of the adhesive layer may be, for example, 300 ⁇ m or less, 250 ⁇ m or less, 200 ⁇ m or less, 150 ⁇ m or less, or 120 ⁇ m or less.
  • the thickness of the adhesive layer is 100 ⁇ m or less, more preferably 75 ⁇ m or less, even more preferably 70 ⁇ m or less, and may be 50 ⁇ m or less, or 30 ⁇ m or less. It may be advantageous from the viewpoint of thinning of the adhesive sheet that the thickness of the adhesive layer is not too large.
  • a thin pressure-sensitive adhesive layer tends to have excellent conformability to an adherend.
  • the technique disclosed herein can be preferably carried out in a mode in which the thickness of the pressure-sensitive adhesive layer is, for example, in the range of 3 ⁇ m to 200 ⁇ m (more preferably 5 ⁇ m to 100 ⁇ m, still more preferably 5 ⁇ m to 75 ⁇ m).
  • the thickness of the pressure-sensitive adhesive layer is at least the thickness of the first pressure-sensitive adhesive layer.
  • the thickness of the second adhesive layer can also be selected from the same range.
  • the thickness of the pressure-sensitive adhesive sheet matches the thickness of the pressure-sensitive adhesive layer.
  • the product of the storage modulus G'(0°C) [Pa] of the adhesive at 0°C and the thickness T [ ⁇ m] of the adhesive layer (G'(0°C) x T) is for example, it is suitably in the range of 5.0 ⁇ 10 4 to 7.5 ⁇ 10 7 , preferably in the range of 5.0 ⁇ 10 4 to 5.0 ⁇ 10 7 .
  • the product (G'(0°C) x T) is limited to a predetermined value or less, the upper limit of the thickness of the adhesive layer and the storage elastic modulus G'(0°C) are limited. , it is easy to obtain excellent flexibility.
  • the product (G′(0° C.) ⁇ T) may be 1.0 ⁇ 10 5 or more, 2.0 ⁇ 10 5 or more, or 8.0 ⁇ 10 5 It can be more than that.
  • the product (G'(0°C) x T) may be 2.0 x 10 7 or less, 1.0 x 10 7 or less, or 6.0 x 10 6 or less. good.
  • the haze value of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet may be, for example, 5.0% or less, preferably 3.0% or less, and 2.0% or less. It is more preferably 1.0% or less, and may be 0.9% or less, 0.8% or less, 0.5% or less, or 0.3% or less.
  • Such a pressure-sensitive adhesive sheet having a highly transparent pressure-sensitive adhesive layer can be used for applications that require high light transmittance (for example, optical applications) in a structure with or without a substrate, and for applications where an adherend is passed through the pressure-sensitive adhesive sheet. It can be preferably applied to applications where good visibility performance is required.
  • the lower limit of the haze value of the pressure-sensitive adhesive layer is not particularly limited, and from the viewpoint of improving transparency, the smaller the haze value, the better.
  • the haze value may be, for example, 0.05% or more, or 0.10% or more, in consideration of the refractive index and adhesion properties.
  • These haze values for the pressure-sensitive adhesive layer are the haze values of the pressure-sensitive adhesive sheet when the technology disclosed herein is implemented in the form of a substrate-less pressure-sensitive adhesive sheet (typically, a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer). can also be preferably applied.
  • haze value refers to the ratio of diffuse transmitted light to total transmitted light when the object to be measured is irradiated with visible light. Also called cloudiness value.
  • the haze value can be measured according to the method described in Examples below.
  • the haze value of the pressure-sensitive adhesive layer can be adjusted, for example, by selecting the composition, thickness, etc. of the pressure-sensitive adhesive layer.
  • the haze value of the pressure-sensitive adhesive sheet may be, for example, 5.0% or less, preferably 3.0% or less, more preferably 2.0% or less, and 1.0%. % or less, and may be 0.9% or less, 0.8% or less, 0.5% or less, or 0.3% or less.
  • a highly transparent pressure-sensitive adhesive sheet can be preferably applied to applications that require high light transmittance (for example, optical applications) and applications that require good visibility of adherends through the pressure-sensitive adhesive sheet.
  • the lower limit of the haze value of the pressure-sensitive adhesive sheet is not particularly limited, and from the viewpoint of improving transparency, the smaller the haze value, the better.
  • the haze value may be, for example, 0.05% or more, or 0.10% or more, in consideration of the refractive index and adhesion properties.
  • the haze value of the pressure-sensitive adhesive sheet can be measured by the same method as for measuring the haze value of the pressure-sensitive adhesive layer.
  • the haze value of the pressure-sensitive adhesive sheet can be obtained by selecting the composition of the pressure-sensitive adhesive layer described above, or by selecting the type of substrate and the thickness of the substrate in a structure having a substrate.
  • the total light transmittance of the pressure-sensitive adhesive layer is preferably 85.0% or more (eg, 88.0% or more, 90.0% or more, or more than 90.0%).
  • a pressure-sensitive adhesive sheet having a highly transparent pressure-sensitive adhesive layer can be used for applications that require high light transmittance (for example, optical applications) in a structure with or without a substrate, and for applications where an adherend is passed through the pressure-sensitive adhesive sheet. It can be preferably applied to applications where good visibility performance is required. Practically, the upper limit of the total light transmittance may be, for example, approximately 98% or less, approximately 96% or less, or approximately 95% or less.
  • the total light transmittance of the adhesive layer may be approximately 94% or less, approximately 93% or less, or approximately 92% or less, taking into account the refractive index and adhesive properties.
  • the total light transmittance is measured using a commercially available transmittance meter in accordance with JIS K 7136:2000. As the transmittance meter, the trade name "Hazemeter HM-150" manufactured by Murakami Color Research Laboratory or its equivalent is used. The total light transmittance can be measured according to the method described in Examples below.
  • the total light transmittance of the pressure-sensitive adhesive layer can be adjusted, for example, by selecting the composition, thickness, etc. of the pressure-sensitive adhesive layer.
  • the total light transmittance of the adhesive sheet is preferably 85.0% or more (eg, 88.0% or more, 90.0% or more, or more than 90.0%).
  • Such highly transparent pressure-sensitive adhesive sheets can be preferably applied to applications that require high light transmittance (for example, optical applications) and applications that require good visibility of adherends through the pressure-sensitive adhesive sheet.
  • the upper limit of the total light transmittance may be, for example, approximately 98% or less, approximately 96% or less, or approximately 95% or less.
  • the total light transmittance of the adhesive sheet may be approximately 94% or less, approximately 93% or less, or approximately 92% or less, in consideration of refractive index and adhesive properties.
  • the total light transmittance of the adhesive sheet can be measured by the same method as for measuring the total light transmittance of the adhesive layer.
  • the total light transmittance of the pressure-sensitive adhesive sheet can be obtained by selecting the composition of the pressure-sensitive adhesive layer described above, or by selecting the type and thickness of the base material in a structure having a base material.
  • the peel strength of the adhesive sheet to the glass plate is not particularly limited.
  • the adhesive sheet has a peel strength to a glass plate of, for example, 1.2 N/25 mm or more, and may be 1.5 N/25 mm or more.
  • the peel strength to the glass plate is 2.0 N/25 mm or more, more preferably 2.5 N/25 mm or more, still more preferably 3.0 N/25 mm or more, and 3.5 N/25 mm or more. It may be 25 mm or more.
  • Such a pressure-sensitive adhesive sheet having a peel strength against a glass plate of a predetermined value or higher is suitable for joining or fixing glass members, for example.
  • the upper limit of the peel strength is not particularly limited, and may be, for example, 30 N/25 mm or less, 25 N/25 mm or less, or 20 N/25 mm or less.
  • the above-mentioned peel strength was measured by pressure bonding to an alkali glass plate as an adherend and leaving it for 30 minutes in an environment of 23° C. and 50% RH, and then peel strength under the conditions of a peel angle of 180 degrees and a tensile speed of 300 mm/min. is grasped by measuring
  • the adhesive sheet to be measured can be reinforced by attaching an appropriate backing material (for example, a polyethylene terephthalate (PET) film having a thickness of about 25 ⁇ m to 50 ⁇ m). More specifically, the peel strength can be measured according to the method described in Examples below.
  • PET polyethylene terephthalate
  • the thickness of the adhesive sheet disclosed herein may be, for example, 1000 ⁇ m or less, 350 ⁇ m or less, 200 ⁇ m or less, 120 ⁇ m or less, or 75 ⁇ m or less. or less than 50 ⁇ m.
  • the thickness of the pressure-sensitive adhesive sheet may be, for example, 5 ⁇ m or more, 10 ⁇ m or more, 25 ⁇ m or more, 80 ⁇ m or more, or 130 ⁇ m or more, from the viewpoint of handleability.
  • the thickness of the pressure-sensitive adhesive sheet refers to the thickness of the portion to be adhered to the adherend. For example, in the pressure-sensitive adhesive sheet 3 having the configuration shown in FIG.
  • the pressure-sensitive adhesive sheet may be in the form of a substrate-attached pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one or both sides of a supporting substrate.
  • the material of the supporting substrate is not particularly limited, and can be appropriately selected according to the intended use, mode of use, etc. of the pressure-sensitive adhesive sheet.
  • Non-limiting examples of substrates that can be used include polyolefin films based on polyolefins such as polypropylene (PP) and ethylene-propylene copolymers, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene Plastic films such as polyester films mainly composed of polyester such as phthalate (PEN), polyvinyl chloride films mainly composed of polyvinyl chloride; foams such as polyurethane foam, polyethylene (PE) foam, polychloroprene foam, etc.
  • polyolefin films based on polyolefins such as polypropylene (PP) and ethylene-propylene copolymers, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene Plastic films such as polyester films mainly composed of polyester such as phthalate (PEN), polyvinyl chloride films mainly composed of polyvinyl chloride; foams such as polyurethane foam, polyethylene (PE
  • Foam sheet ; woven fabric and non-woven fabric made of various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, etc.) alone or blended; paper such as Japanese paper, fine paper, kraft paper, and crepe paper; metal foil such as aluminum foil and copper foil; A base material having a structure in which these are combined may be used.
  • composite substrates include substrates having a structure in which a metal foil and the plastic film are laminated, plastic substrates reinforced with inorganic fibers such as glass cloth, and the like.
  • various film substrates can be preferably used.
  • the film substrate may be a porous substrate such as a foam film or a nonwoven fabric sheet, or may be a non-porous substrate. It may be a substrate having a structure in which is laminated.
  • as the film substrate one containing a resin film that can independently maintain its shape (self-supporting or independent) as a base film can be preferably used.
  • resin film is meant a non-porous structure, typically a substantially voidless resin film. Therefore, the resin film is a concept distinguished from foam films and non-woven fabrics.
  • a film that can maintain its shape independently (self-supporting or independent) can be preferably used.
  • the resin film may have a single-layer structure or a multilayer structure of two or more layers (for example, a three-layer structure).
  • the resin material constituting the resin film examples include polyester; polyolefin; polycycloolefin derived from a monomer having an alicyclic structure such as norbornene structure; polyamide (PA) such as nylon 6, nylon 66, and partially aromatic polyamide.
  • Polyimide such as transparent polyimide (CPI); Polyamideimide (PAI); Polyetheretherketone (PEEK); Polyethersulfone (PES); Polyphenylene sulfide (PPS); Polycarbonate (PC); Polyurethane (PU); Ethylene-vinyl acetate copolymer (EVA); fluorine resin such as polytetrafluoroethylene (PTFE); acrylic resin; cellulose-based polymer such as triacetyl cellulose (TAC); polyarylate; ; and other resins can be used.
  • the resin film may be formed using a resin material containing only one of such resins, or may be formed using a resin material in which two or more of these resins are blended. good too.
  • the resin film may be unstretched or may be stretched (for example, uniaxially stretched or biaxially stretched).
  • a blend film, a cycloolefin polymer (COP) film, a CPI film, a TAC film, etc. can be preferably used.
  • PET films, PEN films, PPS films and PEEK films are examples of preferred resin films from the viewpoint of strength and dimensional stability. PET films and PPS films are particularly preferred from the standpoint of availability, etc., and PET films are particularly preferred.
  • additives such as light stabilizers, antioxidants, antistatic agents, coloring agents (dyes, pigments, etc.), fillers, slip agents, anti-blocking agents, etc. are added to the extent that the effects of the present invention are not significantly hindered. can be blended as needed.
  • the blending amount of the additive is not particularly limited, and can be appropriately set according to the use of the pressure-sensitive adhesive sheet.
  • the method of manufacturing the resin film is not particularly limited.
  • conventionally known general resin film forming methods such as extrusion molding, inflation molding, T-die casting, and calendar roll molding can be appropriately employed.
  • the base material may be substantially composed of such a base film.
  • the substrate may contain an auxiliary layer in addition to the base film.
  • the auxiliary layers include optical property adjusting layers (e.g., colored layers, antireflection layers), printing layers and laminate layers for imparting a desired appearance to the substrate, antistatic layers, undercoat layers, and release layers. and other surface treatment layers.
  • a light-transmissive base (hereinafter also referred to as a light-transmissive base) can be preferably employed as the supporting base.
  • a light-transmissive base can be preferably employed as the supporting base.
  • the total light transmittance of the light transmissive substrate may be, for example, greater than 50% and may be 70% or more.
  • the total light transmittance of the supporting substrate is 80% or higher, more preferably 90% or higher, and may be 95% or higher (eg, 95-100%).
  • the total light transmittance is measured using a commercially available transmittance meter in accordance with JIS K 7136:2000.
  • the transmittance meter As the transmittance meter, the trade name "Hazemeter HM-150" manufactured by Murakami Color Research Laboratory or its equivalent is used.
  • a suitable example of the light-transmitting substrate is a resin film having light-transmitting properties.
  • the light transmissive substrate may be an optical film.
  • the thickness of the base material is not particularly limited, and can be selected according to the purpose and mode of use of the adhesive sheet.
  • the thickness of the base material may be, for example, 500 ⁇ m or less, preferably 300 ⁇ m or less from the viewpoint of handling and workability of the adhesive sheet, may be 150 ⁇ m or less, may be 100 ⁇ m or less, may be 50 ⁇ m or less, or may be 25 ⁇ m. It may be less than or equal to 10 ⁇ m or less.
  • the thickness of the substrate may be, for example, 2 ⁇ m or more, 10 ⁇ m or more, or 25 ⁇ m or more.
  • the surface of the substrate on which the pressure-sensitive adhesive layer is to be laminated may be subjected to corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, or application of a primer to form an undercoat layer, if necessary.
  • Conventionally known surface treatments such as forming may be applied.
  • Such a surface treatment may be a treatment for improving the anchoring property of the pressure-sensitive adhesive layer to the substrate.
  • the composition of the primer used for forming the undercoat layer is not particularly limited, and can be appropriately selected from known ones.
  • the thickness of the undercoat layer is not particularly limited, it is usually suitably about 0.01 ⁇ m to 1 ⁇ m, preferably about 0.1 ⁇ m to 1 ⁇ m.
  • Other treatments that can be applied to the substrate as necessary include antistatic layer forming treatment, colored layer forming treatment, printing treatment, and the like. These treatments can be applied singly or in combination.
  • the adhesive sheet disclosed herein can take the form of an adhesive product in which the surface (adhesive surface) of the adhesive layer is brought into contact with the release surface of the release liner. Accordingly, this specification provides a PSA sheet with a release liner (adhesive product) comprising any of the PSA sheets disclosed herein and a release liner having a release surface in contact with the adhesive surface of the PSA sheet. be.
  • the release liner is not particularly limited.
  • a release liner having a release layer on the surface of a liner substrate such as a resin film or paper (which may be paper laminated with a resin such as polyethylene), or a fluoropolymer (Polytetrafluoroethylene, etc.) and polyolefin resins (Polyethylene, polypropylene, etc.) can be used.
  • a release liner having a release layer on the surface of a resin film as a liner substrate or a release liner made of a resin film formed of a low-adhesive material can be preferably used because of its excellent surface smoothness.
  • the resin film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and examples thereof include polyethylene (PE) film, polypropylene (PP) film, polybutene film, polybutadiene film, polymethylpentene film, and polyvinyl chloride film. , vinyl chloride copolymer film, polyester film (PET film, PBT film, etc.), polyurethane film, ethylene-vinyl acetate copolymer film, and the like.
  • PE polyethylene
  • PP polypropylene
  • PP polybutene film
  • polybutadiene film polymethylpentene film
  • polyvinyl chloride film vinyl chloride copolymer film
  • polyester film PET film, PBT film, etc.
  • polyurethane film ethylene-vinyl acetate copolymer film
  • a silicone-based release agent for example, a silicone-based release agent, a long-chain alkyl-based release agent, an olefin-based release agent, a fluorine-based release agent, a fatty acid amide-based release agent, molybdenum sulfide, silica powder, etc.
  • a known release treatment agent can be used.
  • the use of the pressure-sensitive adhesive sheet disclosed herein is not limited, and it can be used for various purposes. Since the pressure-sensitive adhesive sheet disclosed herein comprises a pressure-sensitive adhesive that has a high refractive index and can have a low elastic modulus, it can be used for various applications that require a high refractive index and flexibility by taking advantage of its characteristics. can be used for For example, in electronic devices such as portable electronic devices, liquid crystal display devices, organic EL (electroluminescence) display devices, PDP (plasma display panels), display devices (image display devices) such as electronic paper, input devices such as touch panels, etc. devices (optical devices), particularly as a pressure-sensitive adhesive sheet for foldable displays and rollable displays.
  • electronic devices such as portable electronic devices, liquid crystal display devices, organic EL (electroluminescence) display devices, PDP (plasma display panels), display devices (image display devices) such as electronic paper, input devices such as touch panels, etc. devices (optical devices), particularly as a pressure-sensitive adhesive sheet for foldable displays and rollable
  • foldable displays and rollable displays it is preferably used as means for bonding, fixing, protecting members having a high refractive index, and the like.
  • the pressure-sensitive adhesive sheet disclosed herein has a high refractive index and is flexible enough to withstand repeated bending operations. It can follow the adherend (foldable display etc.) well. Examples of objects to be attached in such usage patterns include glass members such as window glass and cover glass used in foldable displays and rollable displays.
  • the adhesive sheet disclosed herein easily follows and adheres to a curved surface such as a three-dimensional shape of a mobile electronic device, it is also suitable for use in electronic devices having such a curved shape.
  • the pressure-sensitive adhesive may have excellent heat resistance in addition to having a high refractive index and a low elastic modulus.
  • the portable electronic device is sometimes used in a high-temperature environment, and the internal space of the device may become hot due to the heat generated by the electronic components. Therefore, the heat-resistant adhesive sheet is highly advantageous.
  • Examples of the above portable electronic devices include, for example, mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (for example, wrist wear types worn on the wrist like wristwatches, Modular type to be worn on the body, eyewear type including glasses type (monocular type and binocular type, including head-mounted type), clothing type to be attached to shirts, socks, hats, etc. in the form of accessories, earphones earwear type, etc.), digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game devices, electronic dictionaries, electronic notebooks, electronic books, vehicle information Equipment, portable radios, portable televisions, portable printers, portable scanners, portable modems, etc.
  • the term “portable” means not only being able to be carried around, but also having a level of portability that allows an individual (a typical adult) to carry it relatively easily. shall mean.
  • the material (adherend material) to which the pressure-sensitive adhesive sheet disclosed herein is attached is not particularly limited, but examples include copper, silver, gold, iron, tin, palladium, aluminum, nickel, titanium, Chromium, zinc, etc., or metal materials such as alloys containing two or more of these, for example, polyimide resin, acrylic resin, polyethernitrile resin, polyethersulfone resin, polyester resin (PET resin, polyethylene naphthalate resins, etc.), polyvinyl chloride resins, polyphenylene sulfide resins, polyether ether ketone resins, polyamide resins (so-called aramid resins, etc.), polyarylate resins, polycarbonate resins, diacetyl cellulose and triacetyl cellulose Various resin materials (typically plastic materials) such as cellulose-based polymers, vinyl butyral-based polymers, liquid crystal polymers, etc., inorganic materials such as alumina, zirconia, alkali glass,
  • the member or material (at least one adherend in the double-sided pressure-sensitive adhesive sheet) to which the pressure-sensitive adhesive sheet disclosed herein is attached is made of a material having a higher refractive index than a general acrylic pressure-sensitive adhesive. could be.
  • the refractive index of the adherend material is, for example, 1.50 or more. .66) is also present.
  • Such a high refractive index adherend material is typically a resin material. More specifically, it may be a polyester resin such as PET, a polyimide resin, an aramid resin, a polyphenylene sulfide resin, a polycarbonate resin, or the like.
  • the effect of using the pressure-sensitive adhesive sheet disclosed herein can be favorably exerted on such materials.
  • the upper limit of the refractive index of the adherend material is, for example, 1.80 or less, and may be 1.70 or less.
  • the pressure-sensitive adhesive sheet disclosed herein can be preferably used in a mode of being attached to an adherend (for example, member) having a high refractive index as described above. Suitable examples of such adherends include resin films having a refractive index of 1.50 to 1.80 (preferably 1.55 to 1.75, eg 1.60 to 1.70). The refractive index can be measured by the same method as the refractive index of the adhesive.
  • the member or material to which the pressure-sensitive adhesive sheet is attached may have optical transparency.
  • the total light transmittance of the adherend may be, for example, greater than 50%, preferably 70% or more.
  • the adherend has a total light transmittance of 80% or higher, more preferably 90% or higher, and may be 95% or higher (eg, 95-100%).
  • the pressure-sensitive adhesive sheet disclosed herein can be preferably used in a mode of being attached to an adherend (for example, an optical member) having a total light transmittance of a predetermined value or higher.
  • the total light transmittance is measured using a commercially available transmittance meter in accordance with JIS K 7136:2000.
  • the transmittance meter the trade name "Hazemeter HM-150" manufactured by Murakami Color Research Laboratory or its equivalent is used.
  • the adherend (for example, member) to which the pressure-sensitive adhesive sheet is attached may have the above-described refractive index and the above-described total light transmittance.
  • the refractive index is 1.50 or more (for example, 1.55 or more, 1.58 or more, 1.62 or more, about 1.66, etc.) and the total light transmittance is greater than 50% ( For example, 70% or more, preferably 80% or more, more preferably 90% or more, and further 95% or more).
  • the effect of the technique disclosed herein is particularly preferably exhibited in the aspect of being attached to such a member.
  • An example of a preferred use is optical use. More specifically, for example, it is disclosed herein as an optical pressure-sensitive adhesive sheet that is used for bonding optical members (for bonding optical members) or for manufacturing products (optical products) using the optical members.
  • a pressure-sensitive adhesive sheet that is used can be preferably used.
  • the optical member is a member having optical properties (e.g., polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffraction, optical rotation, visibility, etc.). say.
  • the optical member is not particularly limited as long as it is a member having optical properties.
  • a member constituting a device such as a display device (image display device) or an input device, or used for these devices.
  • Members include, for example, polarizing plates, wave plates, retardation plates, optical compensation films, brightness enhancement films, light guide plates, reflective films, antireflection films, hard coat (HC) films, impact absorption films, antifouling films, Photochromic films, light control films, transparent conductive films (ITO films), design films, decorative films, surface protection plates, prisms, lenses, color filters, transparent substrates, and members in which these are laminated (these are collectively referred to as may be referred to as a "functional film”.) and the like.
  • the above-mentioned "plate” and “film” include forms such as plate-like, film-like, sheet-like, etc.
  • polarizing film includes “polarizing plate”, “polarizing sheet”, etc.
  • a “light guide plate” includes a “light guide film”, a “light guide sheet”, and the like.
  • the above-mentioned "polarizing plate” shall include a circularly polarizing plate.
  • Examples of the display device include a liquid crystal display device, an organic EL display device, a micro LED ( ⁇ LED), a mini LED (miniLED), a PDP, and electronic paper. Moreover, a touch panel etc. are mentioned as said input device.
  • optical member is not particularly limited, but includes, for example, members made of glass, acrylic resin, polycarbonate, PET, metal thin films (for example, sheet-like, film-like, or plate-like members).
  • optical member in this specification also includes members (design films, decorative films, surface protective films, etc.) that play a role of decoration and protection while maintaining the visibility of display devices and input devices.
  • the technology disclosed herein uses, for example, an optical film such as a film having one or more functions such as light transmission, reflection, diffusion, waveguiding, light collection, diffraction, etc., or a fluorescent film, to be used as another optical member ( It may be another optical film.).
  • an optical film such as a film having one or more functions such as light transmission, reflection, diffusion, waveguiding, light collection, diffraction, etc., or a fluorescent film, to be used as another optical member ( It may be another optical film.).
  • an optical film such as a film having one or more functions such as light transmission, reflection, diffusion, waveguiding, light collection, diffraction, etc., or a fluorescent film, to be used as another optical member ( It may be another optical film.).
  • the adhesive disclosed herein can be preferably used for bonding optical films such as light guide films, diffusion films, fluorescent films, toning films, prism sheets, lenticular films, and microlens array films. In these applications, there is a demand for a reduction in thickness and an improvement in light extraction efficiency from the viewpoint of the trend toward miniaturization and higher performance of optical members.
  • the adhesive disclosed herein can be preferably used as an adhesive that can meet such demands. More specifically, for example, in bonding a light guide film or a diffusion film, adjusting the refractive index (for example, increasing the refractive index) of an adhesive layer as a bonding layer can contribute to thinning.
  • the light extraction efficiency (which can also be grasped as luminous efficiency) can be improved by appropriately adjusting the refractive index difference between the fluorescent light emitter and the adhesive.
  • the toning film by appropriately adjusting the refractive index of the pressure-sensitive adhesive so that the refractive index difference between the toning pigment and the toning pigment is small, the scattering component can be reduced, which can contribute to the improvement of the light transmittance.
  • bonding prism sheets, lenticular films, microlens array films, etc. by appropriately adjusting the refractive index of the pressure-sensitive adhesive, light diffraction can be controlled, contributing to improvement in brightness and/or viewing angle.
  • the pressure-sensitive adhesive sheet disclosed herein has good adhesive strength, it is preferably used in a mode in which it is attached to a high-refractive-index adherend (which may be a high-refractive-index layer or member, etc.). Interfacial reflection with an adherend can be suppressed.
  • the pressure-sensitive adhesive sheet used in such an embodiment preferably has a small refractive index difference with the adherend and high adhesion at the interface with the adherend as described above.
  • the thickness uniformity of the pressure-sensitive adhesive layer is high.
  • the surface smoothness of the pressure-sensitive adhesive layer is high.
  • the thickness of the high refractive index adherend is relatively small (for example, when it is 5 ⁇ m or less, 4 ⁇ m or less, or 2 ⁇ m or less), from the viewpoint of suppressing coloring and color unevenness due to interference of reflected light, It is particularly significant to suppress reflections.
  • a usage mode in a polarizing plate with a retardation layer comprising a polarizer, a first retardation layer and a second retardation layer in this order, the bonding and / of the polarizer and the first retardation layer Alternatively, a mode in which it is used for joining the first retardation layer and the second retardation layer is exemplified.
  • the adhesive sheet disclosed herein is suitable for increasing the refractive index, it is preferably attached to a light-emitting layer such as an optical semiconductor (for example, a high-refractive light-emitting layer mainly composed of an inorganic material).
  • a light-emitting layer such as an optical semiconductor (for example, a high-refractive light-emitting layer mainly composed of an inorganic material).
  • the pressure-sensitive adhesive sheet used in such an embodiment preferably has a high-refractive-index pressure-sensitive adhesive layer.
  • the pressure-sensitive adhesive sheet is preferably lightly colored. This can also be advantageous from the viewpoint of suppressing unintentional coloring caused by the adhesive sheet.
  • a self-luminous element means a light-emitting element whose luminance can be controlled by the value of the flowing current.
  • the self-luminous element may be composed of a single body, or may be composed of an aggregate.
  • Specific examples of self-luminous elements include, but are not limited to, light emitting diodes (LEDs) and organic ELs.
  • a light-emitting device means a device including such a self-light-emitting element as a component. Examples of the light-emitting device include, but are not limited to, a light source module device (for example, a planar light-emitting module) used for lighting and a display device in which pixels are formed.
  • the adhesive disclosed herein is used in microlenses and other lens members used as constituent members of cameras, light-emitting devices, etc. (for example, microlenses constituting microlens array films and lens members such as microlenses for cameras).
  • a coating layer covering the lens surface, a bonding layer with a member facing the lens surface (for example, a member having a surface shape corresponding to the lens surface), a filling layer filled between the lens surface and the member, etc. can be preferably used.
  • the adhesive disclosed herein is suitable for increasing the refractive index, it can be used with high refractive index lenses (for example, lenses made of a high refractive index resin or lenses having a surface layer made of a high refractive index resin).
  • the pressure-sensitive adhesive disclosed herein can also be used as a lens resin itself, for example, in the form of being filled in the recesses or voids of a suitable transparent member.
  • Modes for bonding optical members using the pressure-sensitive adhesive sheet disclosed herein are not particularly limited.
  • the optical member may be attached to a member other than the optical member via the pressure-sensitive adhesive sheet disclosed herein, or (3) the pressure-sensitive adhesive sheet disclosed herein may contain the optical member.
  • a mode in which the pressure-sensitive adhesive sheet is attached to an optical member or a member other than an optical member may be employed.
  • the pressure-sensitive adhesive sheet containing an optical member may be, for example, a pressure-sensitive adhesive sheet whose support is an optical member (for example, an optical film).
  • Such a pressure-sensitive adhesive sheet containing an optical member as a support can also be understood as a pressure-sensitive adhesive optical member (for example, pressure-sensitive adhesive optical film).
  • the pressure-sensitive adhesive sheet disclosed herein is a pressure-sensitive adhesive sheet having a support and the functional film is used as the support
  • the pressure-sensitive adhesive sheet disclosed herein is a functional film. It can also be understood as an "adhesive functional film" having the adhesive layer disclosed herein on at least one side.
  • a laminate including the adhesive sheet disclosed herein and a member to which the adhesive sheet is attached is provided.
  • the member to which the pressure-sensitive adhesive sheet is attached may have the refractive index of the adherend material described above.
  • the difference (refractive index difference) between the refractive index of the pressure-sensitive adhesive sheet and the refractive index of the member may be the refractive index difference between the adherend and the pressure-sensitive adhesive sheet described above.
  • the members constituting the laminate are the same as the above-described members, materials, and adherends, so redundant description will not be repeated.
  • a pressure-sensitive adhesive composition comprising an acrylic polymer containing an aromatic ring-containing monomer (A1) as a monomer component, a plasticizer, and an oligomer.
  • A1 acrylic polymer containing an aromatic ring-containing monomer (A1) as a monomer component, a plasticizer, and an oligomer.
  • A1 aromatic ring-containing monomer
  • the oligomer has a weight average molecular weight of 3,000 or more and less than 50,000.
  • the oligomer has a glass transition temperature of 0°C or higher and 200°C or lower.
  • the ratio of the storage modulus G' (0°C) to the storage modulus G' (80°C) at 80°C is in the range of 1 to 1000.
  • the pressure-sensitive adhesive according to any one of [11] to [13] above. [15] The ratio of the storage modulus G' (-10°C) at -10°C to the storage modulus G' (80°C) at 80°C (G'(-10°C)/G' (80°C)) is 1 The pressure-sensitive adhesive according to any one of [11] to [14] above, wherein the range is from 1000 to 1000.
  • a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of [1] to [9] above.
  • a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive according to any one of [11] to [15] above.
  • the product of the storage elastic modulus G'(0°C) [Pa] at 0°C and the thickness T [ ⁇ m] of the pressure-sensitive adhesive layer (G'(0°C) ⁇ T) is 5.0 ⁇ 10 4 to The pressure-sensitive adhesive sheet according to any one of [16] to [18] above, wherein the pressure-sensitive adhesive sheet is within the range of 5.0 ⁇ 10 7 .
  • Example 1> Preparation of acrylic polymer solution
  • benzyl acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat #160", refractive index: 1.519, as a monomer component.
  • Homopolymer Tg 6 ° C..
  • BZA n-butyl acrylate
  • BA n-butyl acrylate
  • AA acrylic acid
  • AIBN isobutyronitrile
  • ethyl acetate a polymerization solvent
  • the acrylic polymer P1 solution (polymer concentration 50%) was diluted with ethyl acetate to a polymer concentration of 30%, and 334 parts of this solution (nonvolatile content 100 parts) was added to 3-phenoxybenzyl alcohol (Tokyo Chemical Industry Co., Ltd.) as a plasticizer.
  • epoxy-based cross-linking agent as a cross-linking agent (Mitsubishi Gas Chemical Co., Ltd., trade name “Tetrad C”, 1 ,3-bis(N,N-diglycidylaminomethyl)cyclohexane) was added and mixed with stirring to prepare an acrylic pressure-sensitive adhesive composition according to this example.
  • Example 2 For 100 parts of the non-volatile matter contained in the solution of the acrylic polymer P1, the product name "ARUFON UC-3000" (acrylic oligomer manufactured by Toagosei Co., Ltd., Mw 10,000, Tg , DSC 58.0 ° C., acid value 74 mg KOH/g, hereinafter referred to as “UC3000”. prepared the product. The oligomers were added as 10% ethyl acetate solutions. A pressure-sensitive adhesive sheet (base-less double-sided pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer) according to this example was produced in the same manner as the pressure-sensitive adhesive sheet according to Example 1, except that the obtained acrylic pressure-sensitive adhesive composition was used.
  • ARUFON UC-3000 acrylic oligomer manufactured by Toagosei Co., Ltd., Mw 10,000, Tg , DSC 58.0 ° C., acid value 74 mg KOH/g, hereinafter referred to as “UC3000”.
  • Example 3 to Example 4 A solution of acrylic polymer P2 was prepared in the same manner as the acrylic polymer solution of Example 1 except that the composition of the monomer components was changed to 90 parts of BZA, 9 parts of 2-ethylhexyl acrylate (2EHA) and 1 part of AA. The Mw of the acrylic polymer P2 was 1,000,000.
  • Acrylic pressure-sensitive adhesive compositions according to Examples 3 and 4 were prepared in the same manner as the acrylic pressure-sensitive adhesive compositions according to Examples 1 and 2, except that the solution of acrylic polymer P2 was used instead of the solution of acrylic polymer P1.
  • Each product is prepared, and each obtained acrylic pressure-sensitive adhesive composition is used to prepare a pressure-sensitive adhesive sheet (base-less double-sided pressure-sensitive adhesive sheet consisting of a pressure-sensitive adhesive layer) according to each example in the same manner as in Example 1. bottom.
  • Acrylic pressure-sensitive adhesive compositions according to Examples 5 and 6 were prepared in the same manner as the acrylic pressure-sensitive adhesive compositions according to Examples 1 and 2, except that the solution of acrylic polymer P3 was used instead of the solution of acrylic polymer P1. were prepared respectively.
  • the acrylic pressure-sensitive adhesive composition according to Example 7 was prepared in the same manner as the acrylic pressure-sensitive adhesive composition according to Example 6, except that the amount of the oligomer added to 100 parts of the non-volatile matter contained in the solution of the acrylic polymer P3 was changed to 10 parts.
  • a system adhesive composition was prepared. Using each obtained acrylic pressure-sensitive adhesive composition, in the same manner as in Example 1, a pressure-sensitive adhesive sheet (a substrate-less double-sided pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer) according to each example was produced.
  • Example 8> (Preparation of oligomer) 100 parts of isobornyl methacrylate (IBXMA) as a monomer component, 0.2 parts of AIBN as a polymerization initiator, and 3.5 parts of ⁇ -thioglycerol as a chain transfer agent and ethyl acetate as a polymerization solvent were charged, stirred in a nitrogen stream for 1 hour to remove oxygen in the polymerization system, and then heated to 70°C. , 1 hour and 2 hours at 80° C. to obtain an oligomer having a solid concentration of 50%.
  • the Mw of the above oligomer was 4300 and the Tg , DSC was 92.4°C.
  • Oligomers of Examples 9 to 13 were prepared in the same manner as the oligomer of Example 8, except that the composition of the monomer components was changed as shown in Table 1.
  • the oligomers of Examples 14 and 15 were obtained by changing the amount of chain transfer agent used in the preparation of the oligomer of Example 12 to increase the Mw.
  • the oligomers of Examples 16 and 17 were obtained by changing the amount of chain transfer agent used in the preparation of the oligomer of Example 13 to increase the Mw.
  • Table 1 shows the Mw, Tg and DSC of each oligomer obtained.
  • An acrylic pressure-sensitive adhesive composition according to each example was prepared in the same manner as the acrylic pressure-sensitive adhesive composition according to Example 8, except that each oligomer obtained above was used as the oligomer.
  • a pressure-sensitive adhesive sheet (base-less double-sided pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer) according to each example was produced in the same manner as the pressure-sensitive adhesive sheet according to Example 1, except that each obtained acrylic pressure-sensitive adhesive composition was used. bottom.
  • the abbreviations of the monomers of the oligomers in Table 1 are as shown below, and the parentheses corresponding to the monomers in Table 1 indicate the weight ratio in the monomer component.
  • IBXMA isobornyl methacrylate
  • CHMA Cyclohexyl methacrylate
  • MMA Methyl methacrylate
  • MAA Methacrylic acid
  • An acrylic pressure-sensitive adhesive composition according to each example was prepared in the same manner as the acrylic pressure-sensitive adhesive composition according to Example 5 except that 5 parts of solid content of 9 ° C., acid value 150 mg KOH / g) was added. .
  • a pressure-sensitive adhesive sheet (base-less double-sided pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer) according to each example was produced in the same manner as the pressure-sensitive adhesive sheet according to Example 1, except that each obtained acrylic pressure-sensitive adhesive composition was used. bottom.
  • the pressure-sensitive adhesive layer (base-less double-sided pressure-sensitive adhesive sheet) according to each example is refracted using an Abbe refractometer (manufactured by ATAGO, model "DR-M4") under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25 ° C. rate was measured.
  • Abbe refractometer manufactured by ATAGO, model "DR-M4"
  • total light transmittance and haze Using a test piece in which the pressure-sensitive adhesive layer according to each example is attached to non-alkali glass (thickness 0.8 to 1.0 mm, total light transmittance 92%, haze 0.4%), a haze meter (Murakami Color Technology Research) The total light transmittance and haze of the above test piece were measured using the "HM-150" (manufactured by the company). The values obtained by subtracting the total light transmittance and haze of the alkali-free glass from the measured values were taken as the total light transmittance [%] and haze [%] of the adhesive (layer).
  • the total light transmittance [%] and haze [%] of the pressure-sensitive adhesive layer are the total light transmittance [%] and haze [%] of the pressure-sensitive adhesive sheet.
  • the release liner was peeled off from one side of the adhesive sheet, and a PET film having a thickness of 50 ⁇ m was laminated and backed, and then cut into a size of 25 mm in width and 100 mm in length. was used as a test piece.
  • the release liner on the other side of the test piece is peeled off, and a 2 kg roller is reciprocated once on the surface of an alkali glass plate (manufactured by Matsunami Glass Industry Co., Ltd., thickness 1.35 mm, polished soda plate edge) as an adherend. and crimped.
  • peel strength (adhesive strength ) [N/25 mm] was measured.
  • a universal tension/compression tester “Tensile/compression tester, TG-1kN” manufactured by Minebea Co., Ltd. was used.
  • backing with a PET film is not essential.
  • a pressure-sensitive adhesive sheet with a release liner according to each example was cut into a rectangle of 2 cm ⁇ 10 cm to obtain a test piece for measurement.
  • a cylindrical bar of ⁇ 4 mm was horizontally fixed at a height sufficient for measurement, and the test piece obtained above was hung on the bar and bent.
  • the test piece was formed into an inverted U shape by hanging the central portion in the longitudinal direction on a bar. Then, both ends located below the test piece were fixed with a clip (13 g), a 60 g weight was suspended and fixed to the clip through a thread of 1 cm in length, and a load was applied to the bent portion of the test piece. .
  • test piece was held in a predetermined temperature environment (-20°C, -10°C or 0°C) for 1 minute, and after 1 minute, the test piece was removed from the bar. Then, under the same temperature environment, the test piece was left still on a horizontal surface with the peak side of the bent portion facing downward for 10 minutes. After standing still for 10 minutes, the time required for the end (short side end) of the test piece to come into contact with the horizontal surface was measured. This test was conducted under the conditions of -20°C, -10°C and 0°C, respectively, and the flexibility was evaluated according to the following criteria.
  • Table 1 shows the outline and evaluation results of the adhesive according to each example.
  • the adhesive containing the acrylic polymer polymerized using the aromatic ring-containing monomer (A1) and the plasticizer had a high refractive index of 1.55 or more. , and a storage elastic modulus G′ (0° C.) of 1.0 ⁇ 10 6 Pa or less.
  • the pressure-sensitive adhesive sheets according to these examples had a low elastic modulus of the pressure-sensitive adhesive, and therefore all of the results of the bending test passed (A or higher).
  • Examples 2, 4, 6 to 21 using pressure-sensitive adhesive compositions containing oligomers compared to Examples 1, 3 and 5 using pressure-sensitive adhesive compositions not containing oligomers, the above-mentioned high refractive index and low elastic modulus While having, the peel strength against glass was improved.
  • the comparison between Examples 1 and 2 the comparison between Examples 3 and 4, and the comparison between Examples 5 and 6 to 21 reveals the effect of improving the adhesive strength by adding the oligomer. From these results, according to the adhesive composition containing the acrylic polymer containing the aromatic ring-containing monomer (A1) as the monomer component, the plasticizer, and the oligomer, the elastic modulus is lowered while having a high refractive index. is possible, and it can be seen that a pressure-sensitive adhesive with improved adhesive strength can be formed.
  • 1, 2, 3 adhesive sheet 10 support substrate 10A first surface 10B second surface 21 adhesive layer, first adhesive layer 21A adhesive surface, first adhesive surface 21B adhesive surface 22 second adhesive layer 22A second adhesive Faces 31, 32 release liner

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  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
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Abstract

L'invention concerne une composition adhésive capable de former un adhésif qui a un indice de réfraction élevé, peut abaisser le module élastique, et présente une résistance adhésive améliorée. La composition adhésive comprend un polymère acrylique contenant un monomère contenant un cycle aromatique (A1) en tant que composant monomère, un plastifiant et un oligomère.
PCT/JP2022/033117 2021-09-14 2022-09-02 Composition adhésive et feuille adhésive Ceased WO2023042686A1 (fr)

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WO2024157791A1 (fr) * 2023-01-23 2024-08-02 三菱ケミカル株式会社 Feuille adhésive photodurcissable, feuille adhésive photodurcissable avec film de démoulage, stratifié pour dispositif d'affichage d'image, et dispositif d'affichage d'image souple

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