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WO2024010042A1 - Adhésif sensible à la pression et feuille adhésive sensible à la pression - Google Patents

Adhésif sensible à la pression et feuille adhésive sensible à la pression Download PDF

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Publication number
WO2024010042A1
WO2024010042A1 PCT/JP2023/024973 JP2023024973W WO2024010042A1 WO 2024010042 A1 WO2024010042 A1 WO 2024010042A1 JP 2023024973 W JP2023024973 W JP 2023024973W WO 2024010042 A1 WO2024010042 A1 WO 2024010042A1
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Prior art keywords
weight
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adhesive
monomer
refractive index
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PCT/JP2023/024973
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English (en)
Japanese (ja)
Inventor
慎太郎 野依
美希 西改
真也 山本
拓也 永田
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Nitto Denko Corp
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Nitto Denko Corp
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Priority to KR1020257003288A priority Critical patent/KR20250033252A/ko
Priority to CN202380051520.2A priority patent/CN119487148A/zh
Publication of WO2024010042A1 publication Critical patent/WO2024010042A1/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
    • 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
    • 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
    • C09J133/062—Copolymers with monomers not covered by C09J133/06
    • C09J133/066—Copolymers with monomers not covered by C09J133/06 containing -OH groups
    • 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
    • C09J133/14—Homopolymers or copolymers of esters of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen
    • 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
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • 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
    • C09J7/10—Adhesives in the form of films or foils without carriers
    • 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]

Definitions

  • the present invention relates to adhesives and adhesive sheets. This application claims priority based on Japanese Patent Application No. 2022-110775 filed on July 8, 2022, and the entire contents of that application are incorporated herein by reference.
  • adhesives also referred to as pressure-sensitive adhesives, hereinafter the same
  • adhesives exhibit a soft solid state (viscoelastic body) in a temperature range around room temperature, and have the property of easily adhering to an adherend under pressure.
  • adhesives are widely used for purposes such as bonding, fixing, and protection in various industrial fields such as home appliances, automobiles, various machines, electrical equipment, and electronic equipment.
  • An example of the use of the adhesive is for joining various light-transmitting members to each other or to other members in display devices such as liquid crystal display devices and organic EL display devices.
  • Technical documents regarding adhesives for optical members include Patent Documents 1 and 2.
  • Patent Documents 1 and 2 disclose an adhesive composition whose main component is a (meth)acrylic acid ester polymer containing a monomer having a plurality of aromatic rings as a monomer unit, and an adhesive obtained by crosslinking the adhesive composition. discloses the use of a monomer having multiple aromatic rings to increase the refractive index of the adhesive to 1.50 or more, particularly preferably 1.51 or more.
  • some materials to which adhesives are attached have a high refractive index
  • a common acrylic adhesive is used to bond such high refractive index materials, the difference in refractive index between the two It is known that reflection occurs at the interface due to By using an adhesive with a high refractive index as the adhesive used for bonding the high refractive materials, the interface reflection can be prevented or suppressed.
  • the refractive index of the acrylic adhesive is usually about 1.47.
  • an adhesive one having good flexibility can be preferably used depending on the application site and usage mode.
  • foldable displays and rollable displays have been put into practical use as displays such as organic EL display devices used in electronic devices such as smartphones. It is necessary to have the flexibility to follow the An adhesive having excellent flexibility easily follows and adheres to curved surfaces such as three-dimensional shapes, and is suitable for use in electronic devices having curved shapes. If the flexibility of an adhesive having a high refractive index can be increased, it is useful because it can be applied to the above-mentioned applications where flexibility is required.
  • high refractive index materials used as monomer components of adhesive polymers tend to have high glass transition temperatures, such as those having aromatic rings.
  • the present invention was created in view of the above circumstances, and aims to provide an adhesive that has both a high refractive index and flexibility.
  • Another object of the present invention is to provide a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive described above.
  • the refractive index is 1.50 or more
  • the ratio of storage elastic modulus G'(25°C) [Pa] to elongation at break E B [%] (G'(25 C)/E B ) is 1 or more and 50 or less.
  • the pressure-sensitive adhesive has a high refractive index and has a ratio (G'(25°C)/E B ) within the above range, so it can exhibit good flexibility.
  • Such adhesives are useful for bonding, fixing, protection, etc. in applications such as foldable display applications, where it is desirable to have a high refractive index, as well as flexibility and elongation deformability that can withstand repeated bending operations. Are suitable.
  • the elongation at break E B is preferably 500% or more.
  • the storage modulus G' (25° C.) is preferably within the range of 1.0 ⁇ 10 4 to 1.0 ⁇ 10 6 .
  • an adhesive having such a low modulus of elasticity, it is easy to obtain good flexibility that satisfies the above ratio (G'(25°C)/E B ).
  • the pressure-sensitive adhesive preferably has a glass transition temperature (Tg) of 0° C. or lower.
  • Tg glass transition temperature
  • a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer made of any pressure-sensitive adhesive disclosed herein (which may be a pressure-sensitive adhesive formed from any pressure-sensitive adhesive composition disclosed herein) is provided.
  • the adhesive disclosed herein is preferably formed into an adhesive sheet and has a high refractive index for applications such as foldable display applications, and is required to have flexibility that can withstand repeated bending operations. It can be preferably used for joining, fixing, protection, etc. in various applications.
  • the thickness of the adhesive layer is 5 ⁇ m or more and 100 ⁇ m or less.
  • the technique disclosed herein can be preferably implemented in an embodiment provided with an adhesive layer having such a thickness.
  • the adhesive sheet has a haze of 3% or less.
  • Adhesive sheets with such high transparency can be preferably used in applications that require high light transmittance (for example, optical applications) and applications that require good visibility of adherends through the adhesive sheet.
  • the total light transmittance of the adhesive sheet is 85% or more.
  • Adhesive sheets with such high transparency can be preferably used in applications that require high light transmittance (for example, optical applications) and applications that require good visibility of adherends through the adhesive sheet.
  • the adhesive sheet according to some embodiments has a peel strength of 0.1 N/25 mm or more to a glass plate.
  • the pressure-sensitive adhesive sheet having the above-mentioned adhesive strength can be preferably used in a manner of being attached to an adherend.
  • FIG. 1 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to an embodiment.
  • 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 an adhesive refers to the main component of the rubbery polymer contained in the adhesive.
  • the above-mentioned rubbery polymer refers to a polymer that exhibits rubber elasticity in a temperature range around room temperature.
  • the term “main component” refers to a component contained in an amount exceeding 50% by weight, unless otherwise specified.
  • the adhesive disclosed herein has a refractive index of 1.50 or more, and a ratio of storage elastic modulus G' (25°C) [Pa] to elongation at break E B [%] (G '(25°C)/E B ) is 1 or more and 50 or less.
  • the refractive index of the adhesive disclosed herein is not particularly limited as long as it is 1.50 or more, and can be set depending on the purpose (for example, in consideration of the refractive index of the adherend). According to the technology disclosed herein, a pressure-sensitive adhesive having such a refractive index, 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, for example, 1.510 or more, 1.520 or more, 1.530 or more, 1.540 or more, 1. It may be .550 or more or 1.560 or more (for example, more than 1.570).
  • the refractive index of the adhesive may be 1.575 or more, 1.580 or more, 1.585 or more, 1.590 or more, 1.595 or more. But that's fine. According to the pressure-sensitive adhesive having such a refractive index, light reflection at the interface with the adherend can be suitably suppressed in a usage mode in which the pressure-sensitive adhesive is attached to a material having a high refractive index.
  • the preferable upper limit of the refractive index of the adhesive is not limited to a specific range because it may vary depending on the refractive index of the adherend, etc., and may be, for example, 1.700 or less, 1.670 or less, and 1. It may be 650 or less, 1.620 or less, or 1.600 or less.
  • the refractive index of the adhesive may be less than 1.595, less than 1.590, less than 1.580, or 1.570. may be less than 1.560, less than 1.550 or less than 1.540.
  • the refractive index of the adhesive can be adjusted, for example, by the composition of the adhesive. For example, it can be adjusted by the type of base polymer, the composition ratio of monomer components, the presence or absence, type, and amount of additives (for example, additive (H RO ), preferably additive (A), etc.) used.
  • the refractive index of an adhesive refers to the refractive index of the surface (adhesive surface) of the adhesive.
  • the refractive index of the adhesive can be measured using a prism coupler under conditions of a measurement temperature of 25° C. and a measurement wavelength of 594 nm.
  • a commercially available measuring device can be used, such as model "2010M” manufactured by Metricon or its equivalent.
  • an adhesive layer made of the adhesive to be evaluated can be used.
  • the refractive index of the adhesive can be measured by the method described in Examples below.
  • the adhesive disclosed herein has a ratio (G'(25°C)/ EB ) of 1 or more and 50 or less. That is, the following formula: 1 ⁇ (G'(25°C)/E B ) ⁇ 50; is satisfied.
  • the above ratio (G'(25°C)/E B ) is the numerical value when the storage elastic modulus G'(25°C) of the adhesive at 25°C is expressed in the unit of "Pa" and the rupture of the adhesive. It is a dimensionless number calculated from the numerical part when time elongation E and B are expressed in units of "%".
  • An adhesive having the above ratio (G'(25°C)/E B ) in the range of 1 or more and 50 or less exhibits good flexibility due to appropriate flexibility and appropriate elongation deformability (resistance to tearing). Therefore, a pressure-sensitive adhesive having a refractive index higher than a predetermined value and having the above ratio (G'(25°C)/E B ) within the above range can achieve both a high refractive index and flexibility.
  • the above-mentioned flexible pressure-sensitive adhesive may be suitable for applications where it is expected to be repeatedly bent, for example.
  • the ratio (G'(25°C)/E B ) is preferably 40 or less (for example, 35 or less), and more preferably 30 or less, from the viewpoint of achieving better suppleness. , 25 or less, 20 or less, 15 or less, or 10 or less. Further, in some embodiments, the ratio (G'(25°C)/E B ) is 2 or more or 3 in consideration of the balance with other properties (for example, optical properties, high temperature properties, low temperature properties, etc.). or more, may be 5 or more, may be 10 or more, may be 15 or more, or may be 20 or more.
  • the elongation at break E B of the adhesive disclosed herein is not particularly limited, and can be appropriately set within a range that can realize a desired ratio (G'(25°C)/E B ).
  • the elongation at break E B of the adhesive may be, for example, in the range of 200% or more and 10,000% or less.
  • the elongation at break E B may be, for example, 300% or more, advantageously 400% or more, preferably 500% or more, more preferably 750% or more. Preferably, it is more preferably 1000% or more.
  • the elongation at break E B of the adhesive is preferably 1250% or more, more preferably 1500% or more, and may be 1750% or more. , 2000% or more, 2250% or more, 2500% or more, 3000% or more, 4000% or more, or 5000% or more.
  • the elongation at break E B of the adhesive is 9000% or less, Advantageously 8000% or less, preferably 7000% or less, more preferably 6000% or less, may be 5500% or less, may be 5000% or less, 4500% or less It may be below, 4000% or less, or 3500% or less.
  • the elongation at break E B of the adhesive can be measured by the method described in Examples below.
  • the elongation at break E B of the adhesive can be adjusted by, for example, selecting the composition of the monomer components constituting the base polymer, selecting the type and amount of additives used, and selecting whether or not to use a crosslinking agent, and selecting the type and amount used. It is possible.
  • the storage modulus G'(25°C) of the adhesive disclosed herein is not particularly limited, and may be appropriately set within a range that can achieve the desired ratio (G'(25°C)/ EB ). can do.
  • the storage modulus G' (25° C.) may be, for example, 1.0 ⁇ 10 6 Pa or less, or 5.0 ⁇ 10 5 Pa or less.
  • the adhesive having the storage modulus G' (25° C.) has appropriate flexibility in the temperature range from around room temperature to higher, and can adhere well to an adherend, for example.
  • the storage elastic modulus G'(25°C) is , advantageously less than 2.0 ⁇ 10 5 Pa, preferably less than 1.5 ⁇ 10 5 Pa, more preferably less than 1.2 ⁇ 10 5 Pa, 1.0 ⁇ It may be less than 10 5 Pa, it may be less than 9.0 x 10 4 , it may be less than 8.0 x 10 4 Pa, it may be less than 7.0 x 10 4 Pa, it may be less than 6.5 x 10 It may be less than 4 Pa, less than 6.0 ⁇ 10 4 Pa, less than 5.0 ⁇ 10 4 Pa, less than 4.0 ⁇ 10 4 Pa, or less than 3.0 ⁇ 10 4 Pa.
  • the lower limit of the storage elastic modulus G' is not particularly limited, and may be, for example, 1.0 ⁇ 10 3 Pa or more, 5.0 ⁇ 10 3 Pa or more, or 6.0 ⁇ 10 3 Pa or more, 8.0 ⁇ 10 3 Pa or more, 1.0 ⁇ 10 4 Pa or more, 1.2 ⁇ 10 4 Pa or more, 1 .5 ⁇ 10 4 Pa or more, 1.6 ⁇ 10 4 Pa or more (for example, more than 1.6 ⁇ 10 4 Pa), or 1.7 ⁇ 10 4 Pa or more.
  • the adhesive tends to have appropriate cohesive strength, for example, in a high temperature range from around room temperature.
  • a pressure-sensitive adhesive having a suitable cohesive force near room temperature is preferable because it can easily achieve both a high refractive index and a ratio (G'(25°C)/E B ) in the above range.
  • the storage modulus G' (25° C.) of the adhesive may be 2.0 ⁇ 10 4 Pa or more, 2.5 ⁇ 10 4 Pa or more, and 3. It may be 5 ⁇ 10 4 Pa or more, or 4.0 ⁇ 10 4 Pa or more.
  • the storage modulus G' (60°C) of the adhesive disclosed herein is not particularly limited, and is suitably less than 1.0 ⁇ 10 6 Pa, preferably less than 5.0 ⁇ less than 10 5 Pa, more preferably less than 2.0 x 10 5 Pa, may be less than 1.5 x 10 5 Pa, may be less than 1.0 x 10 5 Pa, 0.8 It may be less than ⁇ 10 4 Pa.
  • the adhesive whose storage modulus G' (60° C.) is limited as described above has good flexibility in a high temperature range.
  • the lower limit of the storage elastic modulus G' (60° C.) is not particularly limited, and is, for example, 5.0 ⁇ 10 2 Pa or more, suitably 1.0 ⁇ 10 3 Pa or more, preferably 2.0 ⁇ 10 3 Pa or more.
  • Adhesives having the storage modulus G' (60° C.) described above are preferred because they tend to have appropriate cohesive force even in a high temperature range and have excellent heat resistance.
  • the storage modulus G' at -20°C (-20°C) of the adhesive disclosed herein is not particularly limited, and may be, for example, less than 1.0 x 10 9 Pa, and may be less than 2.0 x 10 8 Pa. It is suitable that the pressure is less than 1.5 ⁇ 10 8 Pa, may be less than 1.0 ⁇ 10 8 Pa, may be less than 5.0 ⁇ 10 7 Pa, and may be less than 1.5 ⁇ 10 8 Pa. It may be 0x10 7 Pa or less, 5.0x10 6 Pa or less, 4.0x10 6 Pa or less, or 3.0x10 6 Pa or less.
  • An adhesive whose storage modulus G' (-20° C.) is limited as described above can have particularly excellent flexibility.
  • the lower limit of the storage modulus G' is not particularly limited, and is suitably 5.0 x 10 3 Pa or more, preferably 1.0 x 10 4 Pa or more, more preferably 1.0 x 10 4 Pa or more. It is 5.0 ⁇ 10 4 Pa or more, may be 1.0 ⁇ 10 5 Pa or more, may be 5.0 ⁇ 10 5 Pa or more, or may be 1.0 ⁇ 10 6 Pa or more.
  • An adhesive having the above storage modulus G' (-20° C.) can have flexibility and appropriate cohesive strength. Furthermore, the pressure-sensitive adhesive having the storage elastic modulus G' (-20° C.) tends to have both a high refractive index and flexibility even in a low temperature range.
  • the adhesive has a ratio of a storage modulus G'(25°C) at 25°C to a storage modulus G'(60°C) at 60°C (G'(25°C)/G'(60°C) )) is within the range of 1 to 30. According to an adhesive that satisfies the above characteristics, changes in elastic modulus are suppressed in the temperature range from room temperature to high temperature, so it is easy to exhibit stable characteristics (flexibility, etc.) against temperature changes.
  • the above ratio (G'(25°C)/G'(60°C)) is suitably 10 or less, advantageously 5.0 or less, preferably 4.0 or less (for example, 3.0 or less), and more preferably is 2.5 or less, may be 2.0 or less, or may be 1.8 or less.
  • the lower limit of the ratio (G'(25°C)/G'(60°C)) may be, for example, more than 1.1.
  • the above ratio (G'(25°C)/G'(60°C)) may be 1.2 or more, or 1.3 or more, taking into consideration the balance with other characteristics. , 1.4 or more, or 1.5 or more.
  • the adhesive has a ratio of storage modulus G'(-20°C) to storage modulus G'(25°C) at 25°C (G'(-20°C)/G' (25°C)) is in the range of 1 to 1000.
  • Adhesives that satisfy the above properties suppress changes in elastic modulus in the temperature range from low temperatures to room temperature, so they tend to exhibit stable properties (flexibility, etc.) against temperature changes.
  • the above ratio (G'(-20°C)/G'(25°C)) is suitably 900 or less, preferably 750 or less, more preferably 600 or less, may be 500 or less, and may be 300 or less. It may be 200 or less, 100 or less, or 80 or less.
  • the lower limit of the ratio (G'(-20°C)/G'(25°C)) may be, for example, 1.5 or more, and in consideration of other characteristics, 5.0 or more. It may be 10 or more, 15 or more, or 20 or more.
  • the adhesive has a ratio of storage modulus G'(-20°C) to storage modulus G'(-20°C) at 60°C (G'(-20°C)/G' (60°C)) is in the range of 1 to 3000.
  • the ratio (G'(-20°C)/G'(60°C)) is advantageously 2500 or less, preferably 2000 or less, 1500 or less, 1200 or less, 800 or less. It may be 600 or less, 400 or less, 300 or less, 200 or less, or 100 or less.
  • the lower limit of the above ratio (G'(-20°C)/G'(60°C)) may be, for example, 2.0 or more, and in consideration of other characteristics, 5.0 or more. It may be 10 or more, or it may be 20 or more.
  • the glass transition temperature (Tg) of the adhesive is not particularly limited, and should take into consideration flexibility and elongation deformability in the temperature range around room temperature, flexibility in the low temperature range, and cohesive strength (heat resistance, etc.) in the high temperature range. can be set as follows.
  • the Tg of the adhesive may be, for example, 30°C or less, 20°C or less, 10°C or less, or 5°C or less.
  • the Tg of the adhesive is suitably 0°C or lower, more preferably -5°C or lower, and even more preferably -10°C or lower, from the viewpoint of flexibility and elongation deformability.
  • the temperature may be -15°C or lower (for example, -20°C or lower).
  • the lower the Tg of the adhesive the better the adhesive properties such as adhesion to adherends tend to be. Furthermore, by setting the Tg of the adhesive low, it is possible to suppress changes in the elastic modulus in a temperature range higher than Tg.
  • the lower limit of the Tg of the adhesive is, for example, -50°C or higher, suitably -40°C or higher, and may be -30°C or higher. According to the pressure-sensitive adhesive having the above-mentioned Tg, there is a tendency that an appropriate cohesive force is easily obtained. In addition, there is a tendency to easily form a pressure-sensitive adhesive that has both a high refractive index and flexibility.
  • the storage modulus G' of the adhesive and the glass transition temperature Tg of the adhesive at each of the above temperatures can be measured by the method described in the Examples below, and each storage modulus ratio can be calculated from the results. can.
  • the storage modulus G', storage modulus ratio, and glass transition temperature Tg of the adhesive are determined by, for example, the selection of the composition of the monomer components constituting the base polymer, the selection of the types and amounts of additives, and the use of crosslinking agents. It can be adjusted by selecting the presence or absence, type and amount used.
  • the adhesive disclosed herein can be formed using an adhesive composition containing components (adhesive-forming components) corresponding to the configuration of the adhesive.
  • adhesives are adhesives obtained by curing adhesive compositions in the form of solvent-based, active energy ray-curable, water-dispersed, hot-melt, etc. by drying, crosslinking, polymerization, cooling, etc., that is, the above-mentioned adhesives. It may be a cured product of the agent composition. Only one type of curing means (for example, drying, crosslinking, polymerization, cooling, etc.) for the adhesive composition may be applied, or two or more types may be applied simultaneously or in multiple stages.
  • the composition can typically be dried (and preferably further crosslinked) to form the adhesive.
  • the adhesive is typically formed by irradiating active energy rays to advance a polymerization reaction and/or a crosslinking reaction.
  • active energy ray-curable pressure-sensitive adhesive composition it is preferable to irradiate it with active energy rays after drying.
  • the adhesive disclosed herein can be preferably formed using a solvent-based adhesive composition from the viewpoint of ease of preparation of the adhesive composition.
  • the type of adhesive is not particularly limited, and examples include acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, mixtures thereof, etc.), silicone adhesives, polyester adhesives, and urethane adhesives. It may be an adhesive, a polyether adhesive, a polyamide adhesive, a fluorine adhesive, or the like.
  • the above-mentioned acrylic adhesive refers to an adhesive whose base polymer is an acrylic polymer. The same applies to rubber-based and other adhesives. In some embodiments, acrylic pressure-sensitive adhesives are preferred from the viewpoint of ease of adjusting adhesive properties, optical properties, and the like.
  • 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 will also be referred to as an "acrylic monomer.”
  • an acrylic polymer in this specification is defined as a polymer containing monomer units derived from acrylic monomers.
  • 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 the monomer components constituting the polymer are acrylic monomers.
  • acrylic monomer refers to a monomer having at least one (meth)acryloyl group in one molecule.
  • (meth)acryloyl group comprehensively refers to acryloyl groups and methacryloyl groups. Therefore, the concept of acrylic monomer here may include both monomers having an acryloyl group (acrylic monomer) and monomers having a methacryloyl group (methacrylic monomer).
  • (meth)acrylic acid comprehensively refers to acrylic acid and methacrylic acid
  • (meth)acrylate” comprehensively refers to acrylate and methacrylate, respectively. The same applies to other similar terms.
  • the term "monomer component constituting a polymer” refers to a component that is included in the adhesive composition in the form of a pre-formed polymer (which may be an oligomer), or is contained in the adhesive composition in the form of an unpolymerized monomer. It means a monomer that constitutes a repeating unit (monomer unit) of the polymer in the adhesive formed from the adhesive composition, regardless of whether it is included in the adhesive composition.
  • the monomer component constituting a predetermined polymer (for example, a base polymer, preferably an acrylic polymer) contained in the pressure-sensitive adhesive may be contained in the pressure-sensitive adhesive composition in the form of a polymerized product, an unpolymerized product, or a partially polymerized product. It may be From the viewpoint of ease of preparation of the adhesive composition, in some embodiments, an adhesive composition containing 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. Preferably.
  • an adhesive containing an acrylic polymer as a base polymer (acrylic adhesive) will be mainly explained, but it is not intended that the adhesive in the technology disclosed herein be limited to an acrylic adhesive.
  • the acrylic polymer includes an alkyl (meth)acrylate (hereinafter also referred to as "monomer (m1)") having a chain alkyl group at the ester end as a monomer component constituting the acrylic polymer. It is preferable to include.
  • the chain alkyl group in the monomer (m1) may be linear or branched.
  • the monomers (m1) can be used alone or in combination of two or more.
  • a compound represented by the following formula (1) can be suitably used as the monomer (m1).
  • CH 2 C(R 1 )COOR 2 (1)
  • R 1 in the above formula (1) is a hydrogen atom or a methyl group
  • R 2 is a chain alkyl group.
  • the number of carbon atoms in the chain alkyl group is, for example, 1 to 20, preferably 1 to 18.
  • alkyl (meth)acrylates in which the chain alkyl group has 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate , propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, ( Pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, Nonyl (meth)acrylate, isononyl (meth)acrylate,
  • the content of alkyl (meth)acrylate in the monomer component can be set so that the effect of its use is appropriately exhibited.
  • the content of alkyl (meth)acrylate in the monomer component may be, for example, 1% by weight or more, 5% by weight or more, 10% by weight or more, 20% by weight or more, or 25% by weight or more. , 30% by weight or more, or 35% by weight or more.
  • the content of alkyl (meth)acrylate in the monomer component is suitably 40% by weight or more, and 45% by weight from the viewpoint of easily achieving both high refractive index and flexibility in a well-balanced manner.
  • 50% by weight or more may be 55% by weight or more, 60% by weight or more, 65% by weight or more, 70% by weight
  • the content may be 75% by weight or more, 80% by weight or more, 85% by weight or more, or 90% by weight or more, 95% by weight or more, or 100% by weight.
  • the content of alkyl (meth)acrylate in the monomer component is 99.9% by weight or less, It is preferably 99.8% by weight or less, more preferably 99.6% by weight or less, may be 99.5% by weight or less, may be 99.0% by weight or less, and may be 95% by weight or less. It may be less than 90% by weight, it may be less than 85% by weight, it may be less than 80% by weight, it may be less than 75% by weight, less than 70% by weight, less than 65% by weight, It may be 60% by weight or less or 55% by weight or less.
  • an alkyl (meth)acrylate whose homopolymer has a Tg of -20°C or lower (more preferably -40°C or lower, for example -50°C or lower) is preferably employed. It is possible. Such a low Tg alkyl (meth)acrylate can be useful in lowering the elastic modulus of the adhesive. It can also help improve adhesive properties such as adhesive strength.
  • the lower limit of Tg of the alkyl (meth)acrylate is not particularly limited, and may be, for example, -85°C or higher, -75°C or higher, -65°C or higher, or -60°C or higher.
  • low Tg alkyl (meth)acrylates include n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), heptyl acrylate, octyl acrylate, isononyl acrylate (iNA), and the like.
  • an alkyl (meth)acrylate whose homopolymer Tg is higher than -20°C (for example, higher than -10°C) can be employed as at least a part of the monomer (m1).
  • the upper limit of Tg of the alkyl (meth)acrylate is, for example, 10°C or less, may be 5°C or less, or may be 0°C or less.
  • Alkyl (meth)acrylates having a Tg in this range (hereinafter also referred to as "medium Tg") can be useful for adjusting the elastic modulus of the adhesive.
  • the alkyl (meth)acrylate having the above-mentioned Tg (medium Tg) is preferably used in combination with the above-mentioned low-Tg alkyl (meth)acrylate.
  • a specific example of the medium Tg alkyl (meth)acrylate is lauryl acrylate (LA).
  • LA lauryl acrylate
  • the technology disclosed herein can also be practiced in an embodiment in which medium Tg alkyl (meth)acrylate is not substantially used.
  • C 4-8 alkyl (meth)acrylate As monomer (m1), it is preferred to use C 4-8 alkyl (meth)acrylate as monomer (m1). Among them, it is more preferable to use C 4-8 alkyl acrylate.
  • One type of C 4-8 alkyl (meth)acrylate may be used alone or two or more types may be used in combination. By using C 4-8 alkyl (meth)acrylate, it is easy to reduce the elastic modulus of the adhesive, and there is a tendency that good adhesive properties (adhesion strength, etc.) can be easily obtained.
  • the proportion of C 4-8 alkyl (meth)acrylate in the monomer (m1) is suitably 30% by weight or more.
  • the content 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.
  • the content of C 4-8 alkyl (meth)acrylate in the monomer component is, for example, 1% by weight or more, 5% by weight or more, 10% by weight or more, 20% by weight or more. , 25% by weight or more, 30% by weight or more, or 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, more than 50% by weight, 55% by weight or more, 60% by weight or more, It may be 65% by weight or more, 70% by weight or more, 75% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more, or 100% by weight.
  • the content of C 4-8 alkyl (meth)acrylate in the monomer component is, for example, 99.9% by weight or less, 99.8% by weight or less, 99.6% by weight or less, 99.5% by weight or less. % by weight or less, 99.0% by weight or less, 95% 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, 70% by weight or less, 65% by weight or less, It may be 60% by weight or less or 55% by weight or less.
  • C 1-6 alkyl (meth)acrylate may be preferably used as monomer (m1).
  • the storage modulus in each temperature range can be adjusted.
  • the storage modulus in the high temperature range can be set relatively high.
  • C 1-6 alkyl (meth)acrylates can also help improve transparency (eg, reduce haze).
  • C 1-6 alkyl (meth)acrylate tends to have excellent copolymerizability with the monomer (m3) described below.
  • One type of C 1-6 alkyl (meth)acrylate can be used alone or two or more types can be used in combination.
  • the C 1-6 alkyl (meth)acrylate is preferably C 1-6 alkyl acrylate, more preferably C 2-6 alkyl acrylate, and even more preferably 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 C 2-4 alkyl acrylate.
  • a preferred example of C 1-6 alkyl (meth)acrylate is BA.
  • the content of C 1-6 alkyl (meth)acrylate in the monomer components constituting the acrylic polymer may be, for example, 1% by weight or more, 3% by weight or more, 5% by weight or more, and 8% by weight. The above is fine. From the viewpoint of lowering the elastic modulus and transparency, in some embodiments, the content of the C 1-6 alkyl (meth)acrylate is, for example, 10% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more.
  • the content of C 1-6 alkyl (meth)acrylate in the monomer component is, for example, 99.9% by weight or less, 99.8% by weight or less, 99.6% by weight or less, 99.5% by weight or less.
  • % by weight or less 99.0% by weight or less, 95% 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, 70% by weight or less, 65% by weight or less, It may be 60% by weight or less or 55% by weight or less, and from the viewpoint of better exhibiting the effects of other monomers, 50% by weight or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight % or less, or 5% by weight or less, less than 3% by weight, or less than 1% by weight.
  • the technology disclosed herein can also be practiced in an embodiment in which C 1-6 alkyl (meth)acrylate is not substantially used.
  • C 7-12 alkyl (meth)acrylate may be preferably used as monomer (m1).
  • the storage modulus can be advantageously reduced.
  • C 7-12 alkyl (meth)acrylates can also help improve adhesion (peel strength).
  • One type of C 7-12 alkyl (meth)acrylate can be used alone or two or more types can be used in combination.
  • C 7-12 alkyl (meth)acrylate C 7-10 alkyl acrylate is preferred, C 7-9 alkyl acrylate is more preferred, and C 8 alkyl acrylate is even more preferred.
  • Examples of C 7-12 alkyl (meth)acrylates include 2EHA, iNA, and LA, and a preferred example includes 2EHA.
  • the content of C 7-12 alkyl (meth)acrylate in the monomer components constituting the acrylic polymer may be, for example, 1% by weight or more, 3% by weight or more, 5% by weight or more, and 8% by weight. The above is fine. In some embodiments, the content of the C 7-12 alkyl (meth)acrylate is, for example, 10% by weight or more, 20% by weight or more, 25% by weight from the viewpoint of lowering the elastic modulus, transparency, adhesiveness, etc.
  • the content of C 7-12 alkyl (meth)acrylate in the monomer component is, for example, 99.9% by weight or less, 99.8% by weight or less, 99.6% by weight or less, 99.5% by weight or less.
  • % by weight or less 99.0% by weight or less, 95% 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, 70% by weight or less, 65% by weight or less, It may be 60% by weight or less or 55% by weight or less, and from the viewpoint of better exhibiting the effects of other monomers, 50% by weight or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight % or less, or 5% by weight or less, 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 7-12 alkyl (meth)acrylate.
  • the monomer component includes a monomer (m1)
  • the monomer component includes a monomer (m1)
  • the use of alkyl acrylates is also advantageous in terms of adhesive properties such as adhesive strength.
  • An embodiment may be adopted in which only one or more alkyl acrylates are used as the monomer (m1) and no alkyl methacrylate is used.
  • the monomer component constituting the acrylic polymer may contain a monomer (m2).
  • the monomer (m2) is a monomer that corresponds to at least one of a monomer having a hydroxyl group (hydroxyl group-containing monomer) and a monomer having a carboxyl 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 above-mentioned carboxyl group-containing monomer is a compound containing at least one carboxyl group and at least one ethylenically unsaturated group in one molecule.
  • the monomer (m2) can be useful for introducing crosslinking points into the acrylic polymer and imparting appropriate cohesiveness to the adhesive.
  • the monomers (m2) can be used alone or in combination of two or more.
  • Monomer (m2) is typically a monomer that does not contain an aromatic ring.
  • Examples of the ethylenically unsaturated group that the monomer (m2) has include a (meth)acryloyl group, a vinyl group, and a (meth)allyl group.
  • a (meth)acryloyl group is preferred from the viewpoint of polymerization reactivity, and an acryloyl group is more preferred from the viewpoint of lowering the elastic modulus and adhesiveness.
  • a compound having one ethylenically unsaturated group in one molecule ie, a monofunctional monomer
  • a monofunctional monomer is preferably used as the monomer (m2).
  • a monomer in which the distance between an ethylenically unsaturated group (for example, a (meth)acryloyl group) and a hydroxyl group and/or a carboxy group is relatively long can be used as the monomer (m2).
  • the hydroxyl group and/or carboxy group are used in the crosslinking reaction, a crosslinked structure with high flexibility can be easily obtained.
  • the number of atoms (typically carbon atoms or oxygen atoms) constituting the chain (linking chain) connecting the ethylenically unsaturated group and the hydroxyl group and/or carboxyl group is 3 or more (for example, 4 or more, 5 or more).
  • the upper limit of the number of atoms constituting the connecting chain is, for example, 45 or less, 20 or less (for example, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less or 8 or less).
  • the number of atoms forming a linking chain connecting the ethylenically unsaturated group and the hydroxyl group and/or carboxy group refers to the minimum number of atoms required to reach the hydroxyl group or carboxy group from the ethylenically unsaturated group.
  • the above-mentioned connecting chain is composed of a linear alkylene group (ie, -(CH 2 ) n - group)
  • the number of n is the number of atoms constituting the above-mentioned connecting chain.
  • the connecting chain is an oxyethylene group (that is, a -(C 2 H 4 O) n - group), 3 and n, which is the sum of 2 carbon atoms and 1 oxygen atom, constituting the oxyethylene group.
  • the product (3n) is the number of atoms constituting the connecting chain.
  • such monomers (m2) include, for example, alkylene represented by -(CH 2 ) n - between the ethylenically unsaturated group and the hydroxyl group and/or carboxyl group.
  • oxyalkylene units represented by -(C m H 2m O)- (for example, oxyethylene units where m in the above formula is 2, oxypropylene units where m in the above formulas is 3, oxypropylene units in the above formulas)
  • a compound having at least one oxybutylene unit in which m is 4) can be used.
  • the number of alkylene units and oxyalkylene units is not particularly limited, and may be 1 or more (for example, 1 to 15, 1 to 10, 2 to 6, or 2 to 4).
  • n in the formula representing the above alkylene unit is, for example, an integer from 1 to 10, and may be 2 or more, 3 or more, 4 or more, or 6 or less, or 5 or less. good.
  • m is an integer of 2 or more, for example, an integer of 2 to 4.
  • the monomers (m2) include ester bonds, ether bonds, thioether bonds, aromatic rings, aliphatic rings, and heterocycles. (For example, a ring containing a nitrogen atom (N), an oxygen atom (O), or a sulfur atom (S)).
  • N nitrogen atom
  • O oxygen atom
  • S sulfur atom
  • the above alkylene unit and oxyalkylene unit may have a substituent.
  • hydroxyl group-containing monomers examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and ) Hydroxy (meth)acrylates such as 8-hydroxyoctyl acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. 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, which has a lower Tg, is more preferred.
  • the hydroxyalkyl (meth)acrylate is Monomers with a large number of carbon atoms in the hydroxyalkyl group, such as hydroxyalkyl (meth)acrylates (for example, 4-hydroxy acrylate) in which the hydroxyalkyl group has 3 or more carbon atoms (for example, 3 to 12, preferably 4 to 10). butyl) is preferred.
  • 50% or more (eg, greater than 50%, greater than 70% or greater than 85%) by weight of the monomer (m2) may be 4-hydroxybutyl acrylate.
  • the hydroxyl group-containing monomers can be used alone or in combination of two or more.
  • the hydroxyl group-containing monomer may be one or more selected from compounds that do not have a methacryloyl group.
  • Preferred examples of the hydroxyl group-containing monomer that does not have a methacryloyl group include the above-mentioned various hydroxyalkyl acrylates. For example, it is preferable that 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 (m2) is hydroxyalkyl acrylate.
  • hydroxyalkyl acrylates allows the introduction of hydroxy groups into acrylic polymers that help provide cross-linking points and appropriate cohesive properties, and allows for the introduction of hydroxy groups into acrylic polymers that help provide cross-linking points and impart appropriate cohesive properties, while also being able to be used at room temperature compared to using the corresponding hydroxyalkyl methacrylates alone. It is easy to obtain an adhesive with good flexibility and adhesiveness in this 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 examples include acrylic acid and methacrylic acid.
  • a compound represented by the following formula (2) for example, can be preferably used as the carboxy group-containing monomer.
  • R 1 in the above formula (2) is hydrogen or a methyl group.
  • R 2 and R 3 are divalent linking groups (specifically, organic groups having 1 to 20 carbon atoms (for example, 2 to 10, preferably 2 to 5)), and may be the same as each other. May be different.
  • R 2 and R 3 in the above formula (2) may be, for example, a divalent aliphatic hydrocarbon group, an aromatic hydrocarbon group, or an alicyclic hydrocarbon group.
  • R 2 and R 3 above can be alkylene having 2 to 5 carbon atoms.
  • carboxy group-containing monomer represented by the above formula (2) examples include 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl-phthalic acid, 2-( meth)acryloyloxyethyl-2-hydroxyethyl-phthalic acid, 2-(meth)acryloyloxyethyl-succinic acid, 2-(meth)acryloyloxypropyl hexahydrohydrogen phthalate, 2-(meth)acryloyloxypropylhydrogen phthalate, 2-(meth)acryloyloxypropyltetrahydrohydrogen phthalate, and the like.
  • Carboxy group-containing monomers can be used singly or in combination of two or more. A hydroxyl group-containing monomer and a carboxyl group-containing monomer may be used in combination.
  • the content of the monomer (m2) in the monomer components constituting the acrylic polymer is not particularly limited and can be set depending on the purpose.
  • the content of the monomer (m2) may 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 (m2) is preferably 0.8% by weight or more, may be 1.0% by weight or more, and 3.0% by weight or more. It may be at least 4.0% by weight or at least 4.0% by weight.
  • the upper limit of the content of the monomer (m2) in the monomer component is set so that the total content of the monomer (m2) together with the content of other monomers does not exceed 100% by weight.
  • the content of the monomer (m2) is, for example, 30% by weight or less or 25% by weight or less, and from the viewpoint of better exhibiting the effects of other monomers, 20% by weight or less. It is preferably below, more preferably 15% by weight or less, may be less than 12% by weight, may be less than 10% by weight, and may be less than 7% by weight.
  • the content of the monomer (m2) is 5.0% by weight or less (for example, less than 5.0% by weight), more preferably 3% by weight or less. It may be less than .0% by weight, may be less than 2.0% by weight, and may be less than 1.5% by weight.
  • the total content of monomer (m1) and monomer (m2) in the monomer components constituting the acrylic polymer may be, for example, 21% by weight or more or 31% by weight or more, and the From the viewpoint of easily exhibiting the effect, the content is preferably 41% by weight or more, may be 51% by weight or more, may be 61% by weight or more, may be 71% by weight or more, may be 76% by weight or more, and may be 81% by weight or more. % 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 total content of monomer (m1) and monomer (m2) in the monomer component is, for example, 99% by weight or less, from the viewpoint of facilitating the advantageous effects of monomers other than these. may be 95% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, 60% by weight It may be less than or equal to 55% by weight.
  • the monomer component constituting the acrylic polymer may contain monomer (m3).
  • monomer (m3) a compound containing at least one aromatic ring and at least one ethylenically unsaturated group in one molecule is used.
  • the monomers (m3) can be used alone or in combination of two or more.
  • Examples of the ethylenically unsaturated group that the monomer (m3) has include a (meth)acryloyl group, a vinyl group, and a (meth)allyl group.
  • a (meth)acryloyl group is preferred from the viewpoint of polymerization reactivity, and an acryloyl group is more preferred from the viewpoint of lowering the elastic modulus and adhesiveness.
  • a compound having one ethylenically unsaturated group in one molecule ie, a monofunctional monomer
  • a monofunctional monomer is preferably used as the monomer (m3).
  • the number of aromatic rings contained in one molecule of the compound used as the monomer (m3) may be 1 or 2 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. It is more preferable that the number is 5 or less, 4 or less, 3 or less, or 2 or less.
  • the aromatic ring possessed by the compound used as the monomer (m3) is a benzene ring (it can be a benzene ring that forms part of a biphenyl structure or a fluorene structure); a naphthalene ring, an indene ring, an azulene ring, an anthracene ring, and a phenanthrene ring. It may be a carbocyclic ring such as a condensed ring; , a thiophene ring; and the like may be used.
  • the heteroatoms included as ring constituent atoms in the above-mentioned heterocycle may be, for example, one or more heteroatoms selected from the group consisting of nitrogen, sulfur, and oxygen.
  • the heteroatoms making up the heterocycle can be one or both of nitrogen and sulfur.
  • the monomer (m3) 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 have one or more substituents on the ring-constituting atoms, or may have no substituents.
  • 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, a glycidyloxy group. Examples include, but are not limited to.
  • the number of carbon atoms contained in the substituent is preferably 1 to 4, more preferably 1 to 3, and may be 1 or 2, for example.
  • the aromatic ring has no substituent on the ring constituent atoms, or one or more substituents selected from the group consisting of an alkyl group, an alkoxy group, and a halogen atom (e.g., a bromine atom). It can be an aromatic ring having Note that the aromatic ring of the monomer (m3) having a substituent on its ring-constituting atoms means that the aromatic ring has a substituent other than the substituent having an ethylenically unsaturated group.
  • the aromatic ring and the ethylenically unsaturated group may be bonded directly or may be bonded via a linking group (connecting group).
  • the above-mentioned 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 a hydroxyl group. (for example, a hydroxyalkylene group), an oxy group (-O- group), a thiooxy group (-S- group), and the like.
  • the aromatic ring and the ethylenically unsaturated group are bonded directly or through a linking group selected from the group consisting of alkylene groups, oxyalkylene groups, and poly(oxyalkylene) groups.
  • An aromatic ring-containing monomer having the following structure can be preferably employed.
  • the number of carbon atoms in the alkylene group and the oxyalkylene group is preferably 1 to 4, more preferably 1 to 3, and may be 1 or 2, for example.
  • the repeating number of oxyalkylene units in the poly(oxyalkylene) group may be, for example, 2 to 3.
  • Examples of compounds that can be preferably employed as the monomer (m3) 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 each be used singly or in combination of two or more.
  • One or more aromatic ring-containing (meth)acrylates and one or more aromatic ring-containing vinyl compounds may be used in combination.
  • a monomer having two or more aromatic rings (preferably carbon rings) in one molecule may be used as the monomer (m3) because it is easy to obtain a high refractive index effect.
  • monomers having two or more aromatic rings in one molecule include monomers having a structure in which two or more non-fused aromatic rings are bonded via a linking group, and two or more non-fused aromatic rings.
  • Monomers with a structure in which rings are chemically bonded directly that is, without intervening other atoms
  • monomers with a fused aromatic ring structure monomers with a fluorene structure, monomers with a dinaphthothiophene structure, monomers with a dibenzothiophene structure , etc.
  • the monomer containing multiple aromatic rings can be used alone or in combination of two or more.
  • the above-mentioned linking group is, for example, an oxy group (-O-), a thiooxy group (-S-), an oxyalkylene group (for example, a -O-(CH 2 ) n - group, where n is 1 to 3, preferably 1). , thiooxyalkylene groups (e.g. -S-(CH 2 ) n - group, where n is 1 to 3, preferably 1), linear alkylene groups (i.e.
  • the alkylene group in the above oxyalkylene group, the above thiooxyalkylene group, and the above linear alkylene group may be partially halogenated or completely halogenated.
  • preferred examples of the linking group include an oxy group, a thiooxy group, an oxyalkylene group, and a straight-chain 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 (for example, m-phenoxybenzyl (meth)acrylate), thiophenoxybenzyl (meth) Examples include 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, biphenyl structure-containing (meth)acrylate, triphenyl structure-containing (meth)acrylate, vinyl group-containing biphenyl, etc. Specific examples include o-phenylphenol (meth)acrylate, biphenylmethyl (meth)acrylate, and the like.
  • Examples of the monomer having the fused aromatic ring structure include naphthalene ring-containing (meth)acrylate, anthracene ring-containing (meth)acrylate, vinyl group-containing naphthalene, vinyl group-containing anthracene, and the like.
  • Specific examples include 1-naphthylmethyl (meth)acrylate (also known as 1-naphthalenemethyl (meth)acrylate), hydroxyethylated ⁇ -naphthol acrylate, 2-naphthoethyl (meth)acrylate, 2-naphthoxyethyl acrylate, -(4-methoxy-1-naphthoxy)ethyl (meth)acrylate and the like.
  • the monomer having the above fluorene structure examples include 9,9-bis(4-hydroxyphenyl)fluorene (meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (meth)acrylate etc.
  • the monomer having a fluorene structure includes a structural part 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 the dinaphthothiophene structure include (meth)acryloyl group-containing dinaphthothiophene, vinyl group-containing dinaphthothiophene, (meth)allyl group-containing dinaphthothiophene, and the like. Specific examples include (meth)acryloyloxymethyl dinaphthothiophene (for example, a compound having a structure in which CH 2 CH (R 1 ) C (O) OCH 2 - is bonded to the 5th or 6th position of the dinaphthothiophene ring.
  • R 1 is a hydrogen atom or a methyl group
  • (meth)acryloyloxyethyldinaphthothiophene for example, CH 2 CH(R 1 )C(O) at the 5th or 6th position of the dinaphthothiophene ring
  • R 1 is a hydrogen atom or a methyl group
  • vinyldinaphthothiophene For example, a compound having a structure in which a vinyl group is bonded to the 5th or 6th position of a naphthothiophene ring), (meth)allyloxydinaphthothiophene, and the like.
  • monomers having a dinaphthothiophene structure are included in the above concept of monomers having a fused aromatic ring structure because they include a naphthalene structure or because they have a structure in which a thiophene ring and two naphthalene structures are condensed. Ru.
  • Examples of the monomer having the dibenzothiophene structure include (meth)acryloyl group-containing dibenzothiophene, vinyl group-containing dibenzothiophene, and the like. Note that a monomer having a dibenzothiophene structure has a structure in which a thiophene ring and two benzene rings are condensed, and therefore is included in the concept of a monomer having a condensed aromatic ring structure. Note that neither the dinaphthothiophene structure nor the dibenzothiophene structure corresponds to a structure in which two or more non-fused aromatic rings are directly chemically bonded.
  • a monomer having one aromatic ring (preferably a carbon ring) in one molecule is used as the monomer (m3).
  • a monomer having one aromatic ring in one molecule can be useful, for example, in improving the flexibility of the adhesive, adjusting the adhesive properties, and improving the transparency.
  • the monomer containing a single aromatic ring 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 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, and phenoxypropyl (meth)acrylate.
  • phenoxybutyl (meth)acrylate cresyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, chlorobenzyl (meth)acrylate, and other carbon aromatic ring-containing (meth)acrylates; 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)acrylates such as phenyl
  • the monomer (m3) monomers 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 in which an oxyethylene chain is interposed between an ethylenically unsaturated group and an aromatic ring in this way can be understood as an ethoxylated product of the original monomer.
  • the number of repeating oxyethylene units (-CH 2 CH 2 O-) in the oxyethylene chain is typically 1 to 4, preferably 1 to 3, more preferably 1 to 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.
  • 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.
  • examples include di(meth)acrylate.
  • the content of the monomer containing multiple aromatic rings in the monomer (m3) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, 40% by weight or more, or 50% by weight or more, and may have a higher refractive index. From the viewpoint of making it easier to obtain, the content may be 70% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more.
  • Substantially 100% by weight of the monomer (m3) may be a monomer containing multiple aromatic rings. That is, only one type or two or more types of monomers containing plural aromatic rings may be used as the monomer (m3).
  • the content of the monomer containing multiple aromatic rings in the monomer (m3) is less than 100% by weight, for example, in consideration of the balance between high refractive index, flexibility, and if necessary, adhesive strength. It 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, 25% by weight or less. % or less, or 10% by weight or less.
  • the technology disclosed herein can also be implemented in an embodiment in which the content of the monomer containing multiple aromatic rings in the monomer (m3) 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 constituting the acrylic polymer is not particularly limited, and can be set so as to realize an adhesive that has both 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 20% by weight or more.
  • the content of the monomer containing multiple aromatic rings in the above monomer component is suitably about 60% by weight or less, taking into account the balance between high refractive index, flexibility, and, if necessary, adhesive strength. It may be less than 40% by weight, less than 25% by weight, less than 15% by weight, or less than 5% by weight.
  • the technology disclosed herein can also be practiced in an embodiment in which the content of the monomer containing multiple aromatic rings in the monomer component is less than 3% by weight. A monomer containing multiple aromatic rings may not be used.
  • the content of the monomer containing a single aromatic ring in the monomer (m3) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, 40% by weight or more, or 50% by weight or more, and may have a higher refractive index. From the viewpoint of making it easier to obtain, the content may be 70% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more.
  • Substantially 100% by weight of the monomer (m3) may be a monomer containing a single aromatic ring. That is, only one or more monomers containing a single aromatic ring may be used as the monomer (m3).
  • the content of the monomer containing a single aromatic ring in the monomer (m3) is less than 100% by weight, for example, in consideration of the balance between high refractive index, flexibility, and if necessary, adhesive strength. It 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, 25% by weight or less. % or less, or 10% by weight or less.
  • the technology disclosed herein can also be practiced in an embodiment in which the content of the monomer containing a single aromatic ring in the monomer (m3) is less than 5% by weight. A monomer containing a single aromatic ring may not be used.
  • the content of the monomer containing a single aromatic ring in the monomer component constituting the acrylic polymer is not particularly limited, and can be set so as to realize an adhesive that has both a desired refractive index and flexibility.
  • the content of the monomer containing a single aromatic ring in the monomer component may be, for example, 3% by weight or more, 10% by weight or more, or 20% by weight or more.
  • the content of the monomer containing a single aromatic ring in the above monomer component is suitably about 60% by weight or less, taking into account the balance between high refractive index, flexibility, and if necessary, adhesive strength. It may be less than 40% by weight, less than 25% by weight, less than 15% by weight, or less than 5% by weight.
  • the technology disclosed herein can also be practiced in an embodiment in which the content of the monomer containing a single aromatic ring in the monomer component is less than 3% by weight. A monomer containing a single aromatic ring may not be used.
  • a high refractive index monomer can be preferably employed as at least a part of the monomer (m3).
  • the term "high refractive index monomer” refers to a monomer whose refractive index is, for example, about 1.510 or more, preferably about 1.530 or more, more preferably about 1.550 or more.
  • the refractive index of the high refractive index monomer may be 1.570 or more, 1.600 or more, 1.620 or more, 1.650 or more, It may be 1.675 or more or 1.700 or more.
  • the upper limit of the refractive index of the high refractive index monomer is not particularly limited, but from the viewpoint of ease of preparation of the adhesive composition and compatibility with flexibility suitable as an adhesive, it is, for example, 3.000 or less, and 2. It may be .500 or less, 2.000 or less, 1.900 or less, 1.850 or less, 1.800 or less, 1.750 or less, or 1.700 or less.
  • the high refractive index monomers can be used alone or in combination of two or more.
  • the refractive index of the monomer is measured using an Abbe refractometer at a measurement wavelength of 589 nm and a measurement temperature of 25°C.
  • model "DR-M4" manufactured by ATAGO or its equivalent can be used. If a manufacturer or the like provides a nominal value of the refractive index at 25° C., that nominal value can be used.
  • the above-mentioned high refractive index monomer is one having a corresponding refractive index from among the compounds included in the concept of the aromatic ring-containing monomer (m3) disclosed herein (for example, the compounds and compound groups exemplified above). may be adopted as appropriate.
  • 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 (number of repeating oxyethylene units: 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-acryloyloxymethyl dinaphthothiophene ( 6MDNTA, refractive index: 1.737), 6-methacryloyloxymethyldinaphthothiophene (6MD
  • the content of the high refractive index monomer (that is, the aromatic ring-containing monomer having a refractive index of about 1.510 or more, preferably about 1.530 or more, more preferably about 1.550 or more) in the monomer (m3) is particularly
  • the content is not limited, and may be, for example, 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 (m3) may be, for example, 50% by weight or more, and preferably 70% by weight or more. , 85% by weight or more, 90% by weight or more, or 95% by weight or more.
  • Substantially 100% by weight of the monomers (m3) may be high refractive index monomers.
  • the content of the high refractive index monomer in the monomer (m3) is less than 100% by weight, for example, from the viewpoint of achieving a good balance between high refractive index, flexibility, and if necessary, adhesive strength. It may be 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 constituting the acrylic polymer is not particularly limited, and can be set so as to realize an adhesive that has both desired refractive index and elastic modulus. In addition, if necessary, it may be set in consideration of compatibility with adhesive properties (for example, adhesive strength, etc.) and/or optical properties (for example, 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 20% by weight or more.
  • the content of the high refractive index monomer in the above monomer component is suitably about 60% by weight or less, from the viewpoint of achieving a good balance between high refractive index, flexibility, and if necessary, adhesive strength. It may be less than 5% by weight (for example, less than 50% by weight), less than 40% by weight, less than 25% by weight, less than 15% by weight, less than 5% by weight, and less than 3% by weight. High refractive index monomers may not be used.
  • an aromatic ring-containing monomer (hereinafter sometimes referred to as "monomer L") whose homopolymer Tg is 10° C. or less is employed as at least a part of the monomer (m3).
  • the content of the aromatic ring-containing monomer (m3) in the monomer component (in particular, the aromatic ring-containing monomer (m3) that corresponds to at least one of the above-mentioned aromatic ring-containing monomer, single aromatic ring-containing monomer, and high refractive index monomer)
  • the storage modulus G' of the adhesive generally tends to increase, but by employing monomer L as part or all of the monomer (m3), it is possible to suppress the increase in the storage modulus G'. can.
  • the Tg of the monomer L may be, for example, 5°C or less, 0°C or less, -10°C or less, -20°C or less, or -25°C or less.
  • the lower limit of Tg of the monomer L is not particularly limited. Considering the balance with the refractive index improvement effect, in some embodiments, the Tg of the monomer L may be, for example, -70°C or higher, -55°C or higher, or -45°C or higher. In some other embodiments, the Tg of the 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 alone or in combination of two or more.
  • the monomer L one having a corresponding Tg is appropriately adopted from among the compounds included in the concept of the aromatic ring-containing monomer (m3) disclosed herein (for example, the compounds and compound groups exemplified above). be able to.
  • Suitable examples of aromatic ring-containing monomers that can be used as monomer L include m-phenoxybenzyl acrylate (homopolymer Tg: -35°C), benzyl acrylate (homopolymer Tg: 6°C), phenoxyethyl acrylate (homopolymer Tg: 6°C), (Tg: 2°C), and phenoxydiethylene glycol acrylate (Tg of homopolymer: -35°C).
  • the content of monomer L in the monomer (m3) 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 monomer L in the monomer (m3) may be, for example, 50% by weight or more, from the viewpoint of making it easier to obtain an adhesive that combines a high refractive index and flexibility at a higher level, From the viewpoint of lowering the elastic modulus, the content is preferably 60% by weight or more, 70% by weight or more, 75% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. good.
  • Substantially 100% by weight of the monomers (m3) may be monomer L.
  • the content of monomer L in the monomer (m3) is less than 100% by weight, for example, from the viewpoint of achieving a good balance between high refractive index, flexibility, and if necessary, adhesive strength. It may be 98% by weight or less, 90% by weight or less, 80% by weight or less, or 65% by weight or less.
  • the content of monomer L in the monomer components constituting the acrylic polymer may be, for example, 3% by weight or more, 10% by weight or more, or 20% by weight or more.
  • the content of monomer L in the above monomer component is suitably about 60% by weight or less, and 50% by weight from the viewpoint of achieving a good balance between high refractive index, flexibility, and, if necessary, adhesive strength. It may be less than (for example, less than 50% by weight), it may be less than 40% by weight, it may be less than 25% by weight, it may be less than 15% by weight, it may be less than 5% by weight, and it may be less than 3% by weight.
  • Monomer L may not be used.
  • the aromatic ring-containing monomer (m3) may be preferably selected from compounds that do not include a structure in which two or more non-fused aromatic rings are directly chemically bonded (for example, a biphenyl structure).
  • the monomer component has a composition in which 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 constituted by is preferred. Limiting the amount of compounds that contain a structure in which two or more non-fused aromatic rings are directly chemically bonded in this way allows for a better balance between high refractive index, flexibility, and, if necessary, adhesive strength. This can be advantageous from the viewpoint of realizing an adhesive.
  • the content of the monomer (m3) in the monomer components constituting the acrylic polymer is not particularly limited, and the content of the monomer (m3) in the monomer component constituting the acrylic polymer is not particularly limited, and it can be adjusted to a desired refractive index and elastic modulus, as well as adhesive properties (for example, adhesive strength, etc.) and/or optical properties (for example, total light rays).
  • the pressure-sensitive adhesive can be set so as to achieve both transparency, haze value, etc.).
  • the content of the monomer (m3) in the monomer component may be, for example, 1% by weight or more, 3% by weight or more, 5% by weight or more, 10% by weight or more, or 15% by weight. It may be more than 20% by weight.
  • the content of the monomer (m3) in the monomer component may be 25% by weight or more, 30% by weight or more, 40% by weight or more, 45% by weight. or more or 50% by weight or more.
  • the content of the monomer (m3) in the monomer component is typically less than 100% by weight, suitably less than about 75% by weight (for example, 0% by weight or more and less than 75% by weight), and approximately It is preferably 60% by weight or less, 50% by weight or less (for example, less than 50% by weight), 40% by weight or less, 25% by weight or less, 15% by weight or less, 5% by weight or less It may be less than 3% by weight.
  • the adhesive disclosed herein can also be preferably implemented in an embodiment in which the monomer component constituting the acrylic polymer does not contain the monomer (m3).
  • the monomer components constituting the acrylic polymer may contain monomers other than the above monomers (m1), (m2), and (m3) (hereinafter referred to as "other monomers"), if necessary.
  • the above-mentioned other monomers can be used, for example, for purposes such as adjusting the Tg of the acrylic polymer, adjusting the adhesive performance, and improving compatibility within the adhesive layer.
  • the above-mentioned other monomers can be used alone or in combination of two or more.
  • Examples of the above-mentioned other monomers include monomers having functional groups other than hydroxyl groups and carboxyl groups (functional group-containing monomers).
  • other monomers that can improve the cohesive force 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 (such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, etc.), and nitrogen atom-containing rings.
  • N-vinyl-2-pyrrolidone for example, N-vinyl-2-pyrrolidone, N-(meth)acryloylmorpholine, etc.
  • imide group-containing monomers for example, epoxy group-containing monomers, keto group-containing monomers, isocyanate group-containing monomers, alkoxysilyl group-containing monomers, etc.
  • N-vinyl-2-pyrrolidone also fall under the category of amide group-containing monomers. The same applies to the relationship between the monomer having a nitrogen atom-containing ring and the amino group-containing monomer.
  • 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; etc.
  • an alkoxy group is added as the other monomer.
  • Containing monomers may be preferably used.
  • Alkoxy group-containing monomers can also help reduce haze and improve adhesion.
  • alkoxy group-containing monomers include methoxyethyl acrylate (MEA) (homopolymer Tg: -50°C), ethoxyethoxyethyl acrylate (also known as ethyl carbitol acrylate, homopolymer Tg: -67°C), Examples include alkoxy group-containing acrylates.
  • MEA methoxyethyl acrylate
  • ethoxyethoxyethyl acrylate also known as ethyl carbitol acrylate, homopolymer Tg: -67°C
  • alkoxy group-containing acrylates examples include alkoxy group-containing acrylates.
  • the content of the alkoxy group-containing monomer in the monomer components constituting the acrylic polymer may be, for example, 1% by weight or more, 3% by weight or more, and from the viewpoint of obtaining higher effects, 5% by weight or more.
  • the content may be 10% by weight or more, or may be 15% by weight
  • the content of the alkoxy group-containing monomer in the monomer component may be, for example, 40% by weight or less (for example, 0 to 40% by weight), which facilitates achieving both a high refractive index and a balance of properties as an adhesive. From this point of view, it is advantageous that it is 35% by weight or less, preferably 30% by weight or less, it may be 25% by weight or less, and it may be 22% by weight or less.
  • the amount used is not particularly limited, and can be appropriately set within a range where the total amount of the monomer components does not exceed 100% by weight.
  • the content of the above-mentioned other monomers in the monomer component is, for example, approximately 45% by weight or less (for example, 0 to 45% by weight) from the viewpoint of achieving both a high refractive index and a balance of properties as an adhesive. %), and it is appropriate to make it about 40% by weight or less, about 35% by weight or less, about 30% by weight or less, about 25% by weight or less, about 20% by weight or less It may be about 10% by weight or less, about 5% by weight or less, or about 1% by weight or less.
  • the technology disclosed herein can also be preferably implemented in an embodiment in which the monomer component does not substantially contain the other monomers mentioned above.
  • the monomer components constituting 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. Limiting the amount of the methacryloyl group-containing monomer used in this manner can be advantageous from the viewpoint of realizing a pressure-sensitive adhesive that has a good balance of flexibility, adhesiveness, and high refractive index.
  • the monomer component constituting 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 coloring or discoloration (for example, yellowing) of the 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, 0. It may be less than .05% by weight.
  • This limitation in the amount of carboxy group-containing monomers is due to the fact that metal materials that may be placed in contact with or in close proximity to the adhesive disclosed herein (e.g., metal wiring that may be present on an adherend) This is also advantageous from the viewpoint of suppressing corrosion of metal films, etc.).
  • the technique disclosed herein can be carried out in an embodiment in which the monomer components constituting the acrylic polymer do not contain a carboxy group-containing monomer.
  • the monomer components constituting the acrylic polymer include monomers having acidic functional groups (including carboxy groups, sulfonic acid groups, phosphoric acid groups, etc.). Preferably limited.
  • 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 implemented in an embodiment in which the monomer component does not contain an acidic group-containing monomer (that is, an embodiment in which the acrylic polymer is acid-free).
  • the method for obtaining the acrylic polymer composed of such monomer components is not particularly limited, and may include 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 when performing solution polymerization can be appropriately selected depending on the type of monomer and solvent used, the type of polymerization initiator, etc., and is, for example, about 20°C to 170°C (typically 40°C to 140°C). °C).
  • the solvent (polymerization solvent) used for solution polymerization can be appropriately selected from conventionally known organic solvents.
  • aromatic compounds typically aromatic hydrocarbons
  • acetate esters such as ethyl acetate
  • aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane
  • 1,2-dichloroethane, etc. halogenated alkanes lower alcohols such as isopropyl alcohol (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; etc.
  • Any one type of solvent or a mixed solvent of two or more types can be used.
  • the initiator used for polymerization can be appropriately selected from conventionally known polymerization initiators depending on 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 ; etc.
  • Still another example of the polymerization initiator is a redox initiator using a combination of a peroxide and a reducing agent.
  • One type of polymerization initiator can be used alone or two or more types can be used in combination.
  • the amount of the polymerization initiator used may be any 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. ) can be selected from the range.
  • chain transfer agents such as n-dodecylmercaptan, t-dodecylmercaptan, thioglycolic acid, and ⁇ -thioglycerol can be used.
  • a chain transfer agent that does not contain sulfur atoms (non-sulfur chain transfer agent) may be used.
  • 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.
  • chain transfer agent can be used alone or two or more types can be used in combination.
  • amount used can be, for example, approximately 0.01 to 1 part by weight per 100 parts by weight of the monomer component.
  • the monomer component constituting the base polymer (for example, acrylic polymer) of the adhesive has a composition such that the glass transition temperature TgP based on the composition of the monomer component is approximately 10 ° C. or less. is preferred.
  • the glass transition temperature Tg P is preferably 0° C. or lower (for example, lower than 0° C.), more preferably -10° C. or lower, and even more preferably -20° C. or lower.
  • the temperature may be -57°C or lower.
  • a low glass transition temperature TgP can be advantageous from the viewpoint of lowering the elastic modulus of the adhesive.
  • the lower limit of the glass transition temperature TgP is not particularly limited.
  • the glass transition temperature Tg P may be, for example, ⁇ 70° C. or higher, and is advantageously ⁇ 65° C. or higher from the viewpoint of facilitating the realization of a pressure-sensitive adhesive having appropriate cohesion.
  • the temperature may be -60°C or higher, or -55°C or higher.
  • the glass transition temperature TgP refers to the glass transition temperature determined by the Fox equation based on the composition of the monomer components.
  • Tg is the glass transition temperature of the copolymer (unit: K)
  • Wi is the weight fraction of monomer i in the copolymer (copolymerization ratio on a weight basis)
  • Tgi is the homopolymer of monomer i.
  • Tg glass transition temperature (unit: K) of As the glass transition temperature of the homopolymer used to calculate Tg, the value described in publicly 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 Polymer Handbook, the highest value is used. If the Tg of the homopolymer is not described in known materials, the value obtained by the measurement method described in Japanese Patent Application Publication No. 2007-51271 shall be used.
  • the weight average molecular weight (Mw) of the base polymer is not particularly limited, and may be, for example, approximately 30 ⁇ 10 4 or more, approximately 40 ⁇ 10 4 or more, or approximately 50 ⁇ It may be 10 4 or more.
  • the Mw of the base polymer is suitably 55 ⁇ 10 4 or more, advantageously 60 ⁇ 10 4 or more, preferably 70 ⁇ 10 4 or more, 80 It is more preferably ⁇ 10 4 or more, and may be 90 ⁇ 10 4 or more, 100 ⁇ 10 4 or more, or 120 ⁇ 10 4 or more.
  • additives for example, additive (H RO ), preferably additive (A), etc.
  • H RO additive
  • A additive
  • the upper limit of Mw of the base polymer is, for example, about 500 ⁇ 10 4 or less, and from the viewpoint of adhesive performance, about 400 ⁇ 10 4 or less (more preferably about 300 ⁇ 10 4 or less, for example, about 200 ⁇ 10 4 or less). It is preferably within a range of about 170 ⁇ 10 4 or less, about 150 ⁇ 10 4 or less, or about 130 ⁇ 10 4 or less.
  • the Mw of the base polymer can be determined in terms of polystyrene by gel permeation chromatography (GPC). Specifically, it can be determined by measuring under the following conditions using a GPC measurement device with the trade name "HLC-8220GPC” (manufactured by Tosoh Corporation).
  • the above-mentioned adhesive (e.g., acrylic adhesive) includes, in addition to the base polymer, a high refractive index additive (H RO ) (hereinafter referred to as "additive (H RO )").
  • H RO high refractive index additive
  • the above “H RO” represents an organic material with a high refractive index.
  • the organic material used as the additive (H RO ) may be polymeric or non-polymeric. Further, it may or may not have a polymerizable functional group.
  • the additive (H RO ) is a compound that corresponds to at least one of a compound having a double bond-containing ring and a compound having a heterocycle (which may be a double bond-containing ring), that is, a compound having a heterocycle and a double bond-containing ring.
  • a compound containing the corresponding ring as at least one of the rings can be preferably employed.
  • the refractive index of the adhesive can be efficiently increased.
  • the above compound has an asymmetric structure. This may be more advantageous, for example, from the viewpoint of ease of preparation of the adhesive composition (for example, solubility in a solvent used in a solvent-based adhesive composition), compatibility within the adhesive, and the like.
  • the double bond-containing ring that the additive (H RO ) has may be a conjugated double bond-containing ring (typically an aromatic ring) or a non-conjugated double bond-containing ring. From the viewpoint of increasing the refractive index, it is advantageous for the additive (H RO ) to have at least one ring selected from an aromatic ring and a heterocycle (heterocycle) as the double bond-containing ring. be.
  • the above-mentioned heterocycle may have a structure included in an aromatic ring, or may have a double bond-containing heterocyclic structure different from an aromatic ring.
  • Examples of the double bond-containing ring (typically an aromatic ring) that the additive (H RO ) may have include a benzene ring (which may be a benzene ring forming part of a biphenyl structure or a fluorene structure); a naphthalene ring , an indene ring, an azulene ring, an anthracene ring, a condensed ring of a phenanthrene ring; etc.; a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, It may be a heterocycle such as a triazole ring, oxazole ring, isoxazole ring, thiazole ring, or thiophene ring.
  • the heteroatoms included as ring constituent atoms in the above-mentioned heterocycle may be, for example, one or more heteroatoms selected from the group consisting of nitrogen, sulfur, and oxygen.
  • the heteroatoms making up the heterocycle can be one or both of nitrogen and sulfur.
  • the additive (H RO ) may have a structure in which one or more carbon rings and one or more heterocycles are condensed, such as a dinaphthothiophene structure.
  • the additive is an organic compound having two or more aromatic rings in one molecule (hereinafter referred to as "compound containing multiple aromatic rings") because it is easy to obtain a high refractive index effect. ) 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. Further, the compound containing multiple aromatic rings may be a polymer or a non-polymer.
  • the above polymer is an oligomer (preferably an oligomer having a molecular weight of about 5,000 or less, more preferably about 1,000 or less; for example, a low polymer of about 2 to 5 molecules) containing a monomer containing multiple aromatic rings as a monomer unit.
  • the above oligomers are, for example: homopolymers of monomers containing a plurality of aromatic rings; copolymers of two or more monomers containing a plurality of aromatic rings; copolymers of one or more monomers containing a plurality of aromatic rings with other monomers. It can be a combination; etc.
  • the above-mentioned other monomers may be aromatic ring-containing monomers that do not correspond to monomers containing multiple aromatic rings, may be monomers having no aromatic rings, or may be a combination thereof.
  • Non-limiting examples of compounds containing multiple aromatic rings include compounds having a structure in which two or more non-fused aromatic rings are bonded via a linking group, and compounds in which two or more non-fused aromatic rings are bonded directly (i.e., bonding to other atoms). Examples include a compound having a chemically bonded structure (without intervening), a compound having a fused aromatic ring structure, a compound having a fluorene structure, a compound having a dinaphthothiophene structure, a compound having a dibenzothiophene structure, and the like.
  • the compound containing multiple aromatic rings can be used alone or in combination of two or more.
  • H RO additives
  • examples of compounds that can be used as additives include compounds that can be used as monomers (m3); oligomers containing as monomer units compounds that can be used as monomers (m3); and oligomers that can be used as monomers (m3).
  • a compound that does not have 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 of the group that constitutes an ethylenically unsaturated group groups (e.g., hydroxyl group, amino group, halogen atom, alkyl group, alkoxy group, alkoxyalkyl group, aryloxy group, ester group (acetoxyalkyl group, etc.), hydroxyalkyl group, hydroxyalkyloxy group, glycidyloxy group, etc.) or Examples include, but are not limited to, compounds having a structure in which a hydrogen atom is replaced; and those having a symmetrical structure or an asymmetrical structure.
  • the double bond-containing ring (typically an aromatic ring, preferably a carbocyclic ring) may have one or more substituents on the ring-constituting atoms, or may have no substituents. good.
  • a compound having a double bond-containing ring and having an asymmetric structure due to the above substituents can be preferably used as the additive (H RO ).
  • a compound containing a fused ring having a substituent may be preferably used as the additive (H RO ).
  • the refractive index of the adhesive can be efficiently increased.
  • the above compound may be advantageous from the viewpoint of ease of preparation of the adhesive composition (for example, solubility in a solvent used in a solvent-based adhesive composition) and compatibility within the adhesive.
  • the fused ring having a substituent refers to a fused ring having one or more substituents on the ring constituent atoms of at least one ring included in the fused ring.
  • the fused ring preferably includes a ring that corresponds to at least one of a heterocycle and a double bond-containing ring.
  • a substituted fused ring-containing compound having an asymmetric structure due to the above substituents can be preferably used as the additive (H RO ).
  • the substituent includes an alkyl group, an alkoxy group, an alkoxyalkyl group, an aryloxy group, an ester group (acetoxyalkyl group, etc.), an aryloxy group, Examples include, but are not limited to, hydroxyl groups, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, etc.), ethylenically unsaturated groups, hydroxyalkyl groups, hydroxyalkyloxy groups, glycidyloxy groups, and the like.
  • the number of carbon atoms contained in the substituent is preferably 1 to 4, more preferably 1 to 3, and may be 1 or 2, for example.
  • the double bond-containing ring has no substituents on the ring atoms, or has an alkyl group, an alkoxy group, an alkoxyalkyl group, an ester group, an ethylenically unsaturated group (e.g. (meth)acryloxy It may be an aromatic ring having one or more substituents selected from the group consisting of a hydroxyl group), a hydroxyl group, and a hydroxyalkyl group.
  • preferred substituents include alkyl groups, alkoxy groups, and alkoxyalkyl groups, and the number of carbon atoms contained in these substituents is preferably 1 to 4, more preferably 1 to 3, For example, it can be 1 or 2.
  • a preferred example of a substituted fused ring-containing compound that can be used as an additive (H RO ) is a dinaphthothiophene compound (substituted DNT) having at least one substituent.
  • a pressure-sensitive adhesive containing substituted DNT (for example, substituted DNT with an asymmetric structure) as an additive (H RO ) can preferably achieve both a high refractive index and flexibility.
  • the substituent that the substituted DNT has may be, for example, one or more selected from the group consisting of an alkyl group, an alkoxy group, an alkoxyalkyl group, a (meth)acryloxy group, and a vinyl group. From the viewpoint of lowering the elastic modulus, substituted DNT having one substituent is preferred.
  • substituted DNTs include saturated substituted DNTs such as 6-methoxymethyldinaphthothiophene (6MDNTM, refractive index: 1.759) and 6-ethyldinaphthothiophene (6EDNT, refractive index: 1.764).
  • MDNTM 6-methoxymethyldinaphthothiophene
  • EDNT 6-ethyldinaphthothiophene
  • Examples include substituted DNT having an ethylenically unsaturated substituent, such as 5-vinyldinaphthothiophene (abbreviation: 5VDNT, refractive index: 1.793).
  • a compound having no ethylenically unsaturated group can be preferably employed as the additive (H RO ).
  • H RO the additive
  • This can lead to changes in the properties of the adhesive composition due to heat or light (e.g., decrease in coatability due to progress of gelation or increase in viscosity) or changes in adhesive performance (e.g., elasticity due to reaction of ethylenically unsaturated groups). (increase in elasticity and decrease in elongation deformability) and improve storage stability.
  • Adopting an additive (H RO ) that does not have an ethylenically unsaturated group reduces the possibility of dimensional changes caused by the reaction of the ethylenically unsaturated group in a pressure-sensitive adhesive sheet having an adhesive layer containing the additive (H RO ). It is also preferable from the viewpoint of suppressing the occurrence of optical distortion, deformation (warping, waving, etc.), and optical distortion.
  • a compound with an asymmetric structure can be preferably used as the additive (H RO ).
  • the compound with an asymmetric structure refers to a compound having a molecular structure that is neither linearly symmetrical nor rotationally symmetrical.
  • an additive (H RO ) that is a compound with an asymmetric structure may be referred to as a "high refractive index additive (A)" or simply “additive (A)".
  • a base polymer for example, an acrylic polymer
  • the compound used as the additive (A) has an asymmetric structure means that even if the amount used is relatively large based on 100 parts by weight of the base polymer (for example, acrylic polymer), the degree of increase in the elastic modulus of the adhesive will be moderate. It is advantageous from the viewpoint of Examples of the additive (A) include those having an asymmetric structure among the additives (H RO ) exemplified above.
  • the additive (A) can be used alone or in combination of two or more.
  • the proportion of the additive (A) (A/H RO ) in the total amount of the additive (H RO ) used is not particularly limited, and is in the range of 0% to 100% by weight. You can choose from.
  • the ratio (A/H RO ) may be, for example, 10% by weight or more, 25% by weight or more, or 40% by weight or more.
  • the above ratio (A/H RO ) is suitably 50% by weight or more, and 70% by weight or more. is preferable, and may be 85% by weight or more, 90% by weight or more, or 95% by weight or more.
  • only one or more additives (A) may be used as the additive (H RO ). That is, the above ratio (A/H RO ) may be 100% by weight.
  • the refractive index n a of the compound (which may be a compound corresponding to additive (A)) used as the additive (H RO ) is such that the desired refractive index can be obtained in the adhesive containing the additive (H RO ). It is not limited to a specific range.
  • the refractive index n a of the additive (H RO ) may be, for example, 1.510 or more, 1.530 or more, 1.550 or more, or 1.570 or more. You can.
  • the refractive index n a of the additive (H RO ) is suitably greater than or equal to 1.600, advantageously greater than or equal to 1.620, and advantageously greater than or equal to 1.650.
  • Additives with a higher refractive index (H RO ) provide greater freedom in selecting base polymers that can constitute adhesives with a desired refractive index, for example, by selecting a base polymer with a lower refractive index. It also becomes possible. This can be advantageous from the viewpoint of realizing an adhesive that has both a high refractive index and flexibility in a well-balanced manner.
  • the upper limit of the refractive index n a of the additive (H RO ) is not particularly limited, but from the viewpoint of the low-temperature properties and transparency of the adhesive, it is suitable to be, for example, 3.000 or less, and 2.500 or less. It may be 2.000 or less, 1.900 or less, 1.850 or less, 1.825 or less, or 1.800 or less.
  • the refractive index na of the additive (H RO ) (which may be the additive (A)) is measured using a prism coupler at a measurement wavelength of 594 nm and a measurement temperature of 25°C.
  • a prism coupler a commercially available measuring device can be used, and for example, model "2010M” manufactured by Metricon or its equivalent can be used. If a manufacturer or the like provides a nominal value of the refractive index at 25° C., that nominal value can be used.
  • ⁇ n A may be, for example, 0.010 or more, and from the viewpoint of efficiently exhibiting the refractive index improvement effect by the additive (H RO ), it is advantageous that ⁇ n A is 0.050 or more.
  • ⁇ n A may be, for example, 0.500 or less, and 0.400 or less. It may be less than or equal to 0.300.
  • the above description regarding the refractive index n a and ⁇ n A of the additive (H RO ) can also be applied to the additive (A).
  • the molecular weight of the additive (H RO ) is not particularly limited, and may be, for example, 100 or more, 130 or more, or 150 or more. In some embodiments, the molecular weight of the additive (H RO ) is preferably 170 or more, more preferably 200 or more, and 230 or more, from the viewpoint of increasing the refractive index of the additive (H RO ). It may be more than 250, it may be more than 270, it may be more than 300. In addition, the molecular weight of the additive (H RO ) may be approximately less than 10,000 or less than 5,000, and has the effect of increasing the refractive index and other properties (for example, flexibility suitable for adhesives, optical properties such as haze, etc.).
  • the molecular weight of the additive (H RO ) is preferably less than 3,000, more preferably 1,000 or less, or less than 1,000, may be less than 800, may be 600 or less (for example, less than 600), may be less than 500, It may be less than 400. It may be advantageous that the molecular weight of the additive (H RO ) is not too large from the viewpoint of ease of preparation of the adhesive composition and improvement of compatibility within the adhesive. In some embodiments, a compound having a molecular weight of about 200 to 600 (for example, 300 or more and less than 500) can be preferably used as the additive (H RO ). The above description regarding the molecular weight of the additive (H RO ) can also be applied to the additive (A).
  • the molecular weight of the additive (H RO ) (which can be the additive (A)) is calculated based on the chemical structure for non-polymers or polymers with a low degree of polymerization (for example, about dimers to pentamers).
  • the molecular weight measured using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) can be used.
  • MALDI-TOF-MS matrix-assisted laser desorption ionization time-of-flight mass spectrometry
  • Mw weight average molecular weight
  • the additive (H RO ) is a compound that is typically not gaseous at 25°C and is not a liquid (liquid) or gaseous compound at 25°C. It is preferable that there be.
  • liquid means exhibiting fluidity, and refers to a liquid state as a substance state.
  • Such compounds include those having a melting point above 25°C. Thereby, it is easy to obtain a pressure-sensitive adhesive having an appropriate cohesive force capable of exhibiting desired adhesive properties and elongation deformability.
  • the melting point of the additive (H RO ) is, for example, preferably 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, 60°C or higher, or even 70°C or higher. Generally, the temperature may be 80°C or higher.
  • the upper limit of the melting point of the additive (H RO ) is not particularly limited. In some embodiments, from the viewpoint of ease of preparation of the adhesive composition and transparency of the adhesive, the melting point of the additive (H RO ) may be, for example, 350°C or lower, or 300°C or lower. The temperature may be 250°C or lower, or 200°C or lower.
  • the above description regarding the properties and melting point of the additive (H RO ) can also be applied to the additive (A).
  • the compound used as the additive is preferably soluble in a solvent (typically an organic solvent) from the viewpoint of ease of blending into the adhesive.
  • soluble means that the compound can be dissolved in at least 1.0% by weight (more preferably 2.0% by weight or more, still more preferably 5.0% by weight or more) at 25° C. in at least one general-purpose solvent. It means that the solubility is such that a solution can be prepared at a concentration of 0% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight or more.
  • Examples of the general-purpose solvents include acetate esters such as ethyl acetate and butyl acetate; lower ketones such as acetone and methyl ethyl ketone (MEK); aromatic hydrocarbon solvents such as benzene and toluene; mixed solvents thereof; and the like.
  • acetate esters such as ethyl acetate and butyl acetate
  • lower ketones such as acetone and methyl ethyl ketone (MEK)
  • aromatic hydrocarbon solvents such as benzene and toluene
  • mixed solvents thereof and the like.
  • H RO solubility of the additive
  • the content of the additive (H RO ) in the adhesive disclosed herein can be appropriately set so that an adhesive having desired properties can be obtained.
  • the content of the additive (H RO ) refers to the total content when multiple types of compounds are used as the additive (H RO ).
  • H RO a compound that falls under additive (A) and a compound that does not (i.e., a compound with an asymmetric structure and a compound with a symmetric structure) together as an additive (H RO )
  • their total content is H RO ) content.
  • the content of the additive (H RO ) with respect to 100 parts by weight of the base polymer may be, for example, 5 parts by weight or more or more than 5 parts by weight, 10 parts by weight or more or more than 10 parts by weight, and 20 parts by weight. or more than 20 parts by weight.
  • the content of the additive (H RO ) relative to 100 parts by weight of the base polymer is, for example, 30 parts by weight or more, or It may be more than 30 parts by weight, it may be more than 35 parts by weight, it may be more than 40 parts by weight, it may be more than 45 parts by weight, it may be more than 50 parts by weight, it may be more than 60 parts by weight, The amount may be 65 parts by weight or more.
  • the content of the additive (H RO ) relative to 100 parts by weight of the base polymer may be, for example, 150 parts by weight or less, and the adhesive has an appropriate cohesive force capable of exhibiting desired adhesive properties and elongation deformability.
  • the amount is suitably 120 parts by weight or less, preferably 100 parts by weight or less, 90 parts by weight or less, 80 parts by weight or less, 75 parts by weight or less. 70 parts by weight or less, 65 parts by weight or less, 60 parts by weight or less, 55 parts by weight or less, 50 parts by weight or less, or 45 parts by weight or less.
  • the content of the additive (A) in the adhesive disclosed herein can be appropriately set so as to obtain an adhesive with desired properties.
  • the content of the additive (A) refers to the total content when multiple types of compounds are used as the additive (A).
  • the content of the additive (A) relative to 100 parts by weight of the base polymer may be, for example, 5 parts by weight or more or more than 5 parts by weight, 10 parts by weight or more or more than 10 parts by weight, and 20 parts by weight or more. Or it may be more than 20 parts by weight.
  • the content of the additive (A) relative to 100 parts by weight of the base polymer is, for example, 30 parts by weight or more, or The amount may be more than 35 parts by weight, and from the viewpoint of better achieving the effect of lowering the elastic modulus and/or increasing the refractive index, it is preferably 35 parts by weight or more, more preferably 40 parts by weight or more. The amount may be 45 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, or 65 parts by weight or more. Further, the content of the additive (A) relative to 100 parts by weight of the base polymer may be, for example, 150 parts by weight or less to obtain an adhesive having an appropriate cohesive force capable of exhibiting desired adhesive properties and elongation deformability.
  • the amount is suitably 120 parts by weight or less, preferably 100 parts by weight or less, may be 90 parts by weight or less, may be 80 parts by weight or less, and may be 75 parts by weight.
  • the content of the additive (A) relative to 100 parts by weight of the base polymer may be 70 parts by weight or less, and may be 65 parts by weight or less.
  • the amount may be 60 parts by weight or less, 55 parts by weight or less, 50 parts by weight or less, or 45 parts by weight or less.
  • the adhesive composition used to form the adhesive disclosed herein may contain a crosslinking agent, if necessary, for purposes such as adjusting the cohesive force of the adhesive.
  • a crosslinking agent known in the adhesive field, such as an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, an oxazoline crosslinking agent, a melamine resin, a metal chelate crosslinking agent, etc. Can be done.
  • isocyanate-based crosslinking agents and epoxy-based crosslinking agents can be preferably employed.
  • Other examples of crosslinking agents include monomers having two or more ethylenically unsaturated groups in one molecule, ie, polyfunctional monomers.
  • One type of crosslinking agent can be used alone or two or more types can be used in combination.
  • a bifunctional or higher-functional isocyanate compound can be used, such as aliphatic polystyrene such as trimethylene diisocyanate, butylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), dimer acid diisocyanate, etc.
  • aliphatic polystyrene such as trimethylene diisocyanate, butylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), dimer acid diisocyanate, etc.
  • Isocyanates Alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane; 2,4-tolylene diisocyanate, 4,4'- Aromatic isocyanates such as diphenylmethane diisocyanate and xylylene diisocyanate (XDI); the above isocyanate compounds are modified with allophanate bonds, biuret bonds, isocyanurate bonds, uretdione bonds, urea bonds, carbodiimide bonds, uretonimine bonds, oxadiazinetrione bonds, etc.
  • modified polyisocyanates for example, isocyanurate of HDI, allophanate of HDI, etc.
  • polyhydric alcohol adducts of the above-mentioned isocyanate compounds for example, trimethylolpropane adduct of XDI, etc.
  • examples of commercially available products include the trade names Takenate 300S, Takenate 500, Takenate 600, Takenate D110N, Takenate D120N, Takenate D140N, Takenate D160N, Takenate D165N, Takenate D178N, Takenate D178NL (all manufactured by Mitsui Chemicals), and Sumidur T80.
  • the isocyanate compounds can be used alone or in combination of two or more.
  • a bifunctional isocyanate compound and a trifunctional or more functional isocyanate compound may be used together.
  • epoxy crosslinking agent examples include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, and 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 alone or in combination of two or more.
  • 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 crosslinking agent is a bifunctional crosslinking agent having two crosslinking reactive groups (eg, isocyanate groups) per molecule.
  • a bifunctional crosslinking agent By using a bifunctional crosslinking agent, a flexible crosslinked structure can be easily formed.
  • One kind of bifunctional crosslinking agent can be used alone or two or more kinds can be used in combination.
  • a bifunctional crosslinking agent may be used in combination with a trifunctional or more functional crosslinking agent.
  • an acyclic crosslinking agent (also referred to as a chain crosslinking agent) that does not have a ring structure such as an aromatic ring or an aliphatic ring is preferably used as the crosslinking agent.
  • a ring structure such as an aromatic ring or an aliphatic ring
  • isocyanate-based crosslinking agents it is preferable to use isocyanate-based compounds that do not have a ring structure such as an aromatic ring or an isocyanurate ring.
  • acyclic isocyanates include aliphatic isocyanate compounds (e.g., PDI and HDI) and modified aliphatic isocyanate compounds (e.g., allophanate bonds, biuret bonds, urea bonds, and carbodiimide bonds of PDI and HDI). modified polyisocyanates).
  • aliphatic isocyanate compounds e.g., PDI and HDI
  • modified aliphatic isocyanate compounds e.g., allophanate bonds, biuret bonds, urea bonds, and carbodiimide bonds of PDI and HDI. modified polyisocyanates.
  • One type of acyclic crosslinking agent can be used alone or two or more types can be used in combination.
  • an acyclic bifunctional crosslinking agent may be used as the crosslinking agent.
  • a crosslinking agent in which the distance between one crosslinking reactive group (for example, an isocyanate group) and another crosslinking reactive group in one molecule is relatively long may be used as the crosslinking agent.
  • a flexible crosslinked structure having a length longer than a predetermined length is formed.
  • a compound in which the number of atoms constituting a linking chain connecting one crosslinking reactive group and another crosslinking reactive group in one molecule of the crosslinking agent is 10 or more (for example, 12 or more or 14 or more) is used as a crosslinking agent. It can be used as The upper limit of the number of atoms constituting the connecting chain is not particularly limited as it can be prepared by polymerization etc.
  • the number of atoms constituting a linking chain linking the above-mentioned cross-linking-reactive groups refers to the number of atoms constituting a linking chain that connects the above-mentioned cross-linking-reactive groups, from one cross-linking-reactive group to another cross-linking-reactive group (if it has 3 or more cross-linking-reactive groups, the number of The minimum number of atoms required to reach the crosslinking-reactive group (the closest cross-linking-reactive group).
  • crosslinking agents having a connecting chain can be used alone or in combination of two or more.
  • an acyclic bifunctional crosslinking agent may be used as the crosslinking agent.
  • commercially available crosslinking agents include Coronate 2770 (manufactured by Tosoh Corporation), Takenate D178NL (manufactured by Mitsui Chemicals), Duranate A201H (manufactured by Asahi Kasei Corporation), and the like.
  • the amount used is not particularly limited, and is, for example, in the range of about 0.001 parts by weight to 5.0 parts by weight based on 100 parts by weight of the above monomer components. can do.
  • the amount of the crosslinking agent used per 100 parts by weight of the monomer component is preferably 3.0 parts by weight or less, more preferably 2.0 parts by weight or less. , 1.0 part by weight or less, 0.5 part by weight or less, or 0.2 part by weight or less.
  • the amount of the crosslinking agent used per 100 parts by weight of the monomer component may be, for example, 0.005 parts by weight or more, and 0.01 parts by weight. parts by weight or more, 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, 0.4 parts by weight or more. But that's fine.
  • a crosslinking catalyst may be used to advance the crosslinking reaction more effectively.
  • the crosslinking catalyst include metal crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, zirconium tetraacetylacetonate, ferric nathem, butyltin oxide, and dioctyltin dilaurate.
  • metal crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, zirconium tetraacetylacetonate, ferric nathem, butyltin oxide, and dioctyltin dilaurate.
  • tin-based crosslinking catalysts such as dioctyltin dilaurate are preferred.
  • the amount of crosslinking catalyst used is not particularly limited.
  • the amount of the crosslinking catalyst to be used per 100 parts by weight of the monomer component is, for example, in the range of approximately 0.0001 part by weight or more and 1 part by weight or less, taking into consideration the balance between the speed of the crosslinking reaction and the length of the pot life of the adhesive composition.
  • the content is preferably in the range of 0.001 part by weight or more and 0.5 part by weight or less.
  • the adhesive composition may contain a compound that causes keto-enol tautomerism as a crosslinking retarder.
  • a compound that causes keto-enol tautomerism can be preferably used in a pressure-sensitive adhesive composition containing an isocyanate-based crosslinking agent.
  • Various ⁇ -dicarbonyl compounds can be used as the compound that causes keto-enol tautomerism.
  • ⁇ -diketones acetylacetone, 2,4-hexanedione, etc.
  • acetoacetate esters methyl acetoacetate, ethyl acetoacetate, etc.
  • 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 or less, based on 100 parts by weight of the monomer component.
  • the content may be 1 part by weight or more and 5 parts by weight or less.
  • the adhesive disclosed herein may contain a tackifier.
  • tackifiers include rosin-based tackifying resins, terpene-based tackifying resins, phenol-based tackifying resins, hydrocarbon-based tackifying resins, ketone-based tackifying resins, polyamide-based tackifying resins, epoxy-based tackifying resins, and elastomers.
  • Known tackifier resins such as tackifier resins can be used. These can be used alone or in combination of two or more.
  • the amount of the tackifying resin used is not particularly limited, and can be set so that appropriate adhesive performance is exhibited depending on the purpose and use.
  • the amount of tackifier used per 100 parts by weight of the monomer component is suitably 30 parts by weight or less, preferably 10 parts by weight or less. , more preferably 5 parts by weight or less.
  • the technology disclosed herein can be preferably practiced without using a tackifier.
  • High refractive index particles The adhesive disclosed herein can contain high refractive index particles as an optional component.
  • high refractive index particles refers to particles that can be incorporated into an adhesive to increase the refractive index of the adhesive.
  • the high refractive index particles may be referred to as "particles P HRI ".
  • HRI means high refractive index.
  • the particle P HRI is made of a material having a refractive index of, for example, 1.60 or more, preferably 1.70 or more (may be 1.80 or more, 1.90 or more, or even 2.00 or more). One or more of the configured particles may be used.
  • the upper limit of the refractive index of the material constituting the particles P HRI is not particularly limited, and may be, for example, 3.00 or less, 2.80 or less, 2.50 or less, 2.20 or less, It may be 2.00 or less.
  • the refractive index of the material constituting the particle P HRI was measured using a commercially available spectroscopic ellipsometer at a measurement wavelength of 589 nm and a measurement temperature of 25°C for a single layer film (thickness that allows refractive index measurement) of the material. This is the refractive index measured under the following conditions.
  • the spectroscopic ellipsometer for example, the product name "EC-400" (manufactured by JA. Woolam) or its equivalent product is used.
  • the type of particle 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.
  • the particles P HRI those that can improve the refractive index of the pressure-sensitive adhesive sheet can be preferably used from among inorganic oxides (for example, metal oxides).
  • Suitable examples of materials constituting the particles P HRI include titania (titanium oxide, TiO 2 ), zirconia (zirconium oxide, ZrO 2 ), aluminum oxide, zinc oxide, tin oxide, copper oxide, barium titanate, niobium oxide ( Examples include inorganic oxides (specifically metal oxides) such as Nb 2 O 5 etc.). Particles made of these inorganic oxides (for example, metal oxides) can be used singly or in combination of two or more. Among these, particles made of titania or zirconia are preferable, and particles made of zirconia are particularly preferable.
  • metal particles for example, iron-based, zinc-based, tungsten-based, or platinum-based materials can have a high refractive index.
  • organic particles particles made of resin such as styrene resin, phenol resin, polyester resin, and polycarbonate resin have a relatively high refractive index.
  • the organic-inorganic composite particles include composites of the above-mentioned inorganic materials and organic materials, and inorganic particles coated with organic materials such as resins.
  • the particles P HRI from the viewpoint of compatibility with the adhesive component, the above-mentioned organic or inorganic particles surface-treated with a surface treatment agent may be used.
  • the average particle diameter of the particles P HRI is not particularly limited, and particles of an appropriate size that can realize a desired refractive index improvement by being included in the adhesive may be used.
  • the average particle diameter of the particles P HRI can be, for example, about 1 nm or more, and suitably about 5 nm or more. From the viewpoint of improving the refractive index and handling properties, the average particle diameter of the particles P HRI is preferably about 10 nm or more, may be about 20 nm or more, or may be about 30 nm or more.
  • the upper limit of the average particle diameter is, for example, approximately 300 nm or less, and from the viewpoint of improving the refractive index, it is preferably approximately 100 nm or less, more preferably approximately 70 nm or less, and even more preferably It is approximately 50 nm or less, and may be approximately 35 nm or less (for example, approximately 25 nm or less).
  • the average particle diameter of the particle P HRI mentioned above refers to the volume average particle diameter, and specifically, the particle size distribution measured for the particle P HRI dispersion using a particle size distribution measuring device based on a laser scattering/diffraction method. It refers to the particle diameter at an integrated value of 50% (50% volume average particle diameter; hereinafter sometimes abbreviated as D50 ).
  • the measuring device for example, the product name "Microtrac MT3000II" manufactured by Microtrac Bell Co., Ltd. or its equivalent can be used.
  • the content of particle P HRI in the adhesive is not particularly limited.
  • the content of the particles P HRI may vary depending on the desired refractive index.
  • the content of the particles P HRI can be appropriately set in consideration of required adhesive properties and the like so as to provide a refractive index of a predetermined value or more.
  • the content of particle P HRI in the adhesive can be, for example, about 75% by weight or less, and may be about 50% by weight or less from the viewpoint of adhesive properties and transparency, and may be about 30% by weight.
  • the lower limit of the content of particle P HRI is not particularly limited, and may be, for example, more than 0% by weight, more than 1% by weight, or more than 5% by weight.
  • the content of particulate P HRI in the adhesive is, for example, less than 10% by weight, may be less than 1% by weight, and 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 particle P HRI .
  • the content of particulate P HRI in an adhesive can also be specified in relation to the amount of base polymer included in the adhesive.
  • the content of the particle P HRI can be, for example, about 100 parts by weight or less with respect to 100 parts by weight of the base polymer, and may be about 60 parts by weight or less from the viewpoint of adhesive properties and transparency, and may be about 40 parts by weight. The following may be used.
  • the lower limit of the content of particle P HRI is not particularly limited, and may be, for example, more than 0 parts by weight, 1 part by weight or more, or 5 parts by weight or more with respect to 100 parts by weight of the base polymer.
  • the content of particle P HRI is, for example, less than 30 parts by weight, may be less than 10 parts by weight, may be less than 1 part by weight, based on 100 parts by weight of the base polymer, It may be less than 0.1 part by weight.
  • the adhesive disclosed herein or the adhesive composition used to form the adhesive may contain plasticizers, softeners, colorants (dyes, pigments, etc.) to the extent that the effects of the present invention are not significantly impaired.
  • fillers, antistatic agents, antiaging agents, ultraviolet absorbers, antioxidants, light stabilizers, preservatives, and other known additives that can be used in adhesives may be included as necessary.
  • conventionally known ones can be used in a conventional manner, and since they do not particularly characterize the present invention, detailed explanations will be omitted.
  • the adhesives according to some embodiments have a limited content of liquid compounds at 25°C. This can be advantageous from the viewpoint of achieving both appropriate cohesion and elongation deformability and a high refractive index.
  • the content of the compound which is liquid at 25° C. is suitably less than 30 parts by weight, preferably less than 20 parts by weight or less than 10 parts by weight, based on 100 parts by weight of the base polymer. It is preferably less than 5 parts by weight, more preferably less than 3 parts by weight or less than 1 part by weight.
  • the adhesive may be substantially free of compounds that are liquid at 25°C.
  • 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 adhesive sheet may be a base-attached adhesive sheet having the adhesive layer on one or both sides of a non-peelable base material (supporting base material), and the adhesive layer is held by a release liner.
  • a pressure-sensitive adhesive sheet without a base material that is, a pressure-sensitive adhesive sheet without a non-peelable base material; typically a pressure-sensitive adhesive sheet consisting of a pressure-sensitive adhesive layer
  • a pressure-sensitive adhesive sheet without a base material that is, a pressure-sensitive adhesive sheet without a non-peelable base material; typically a pressure-sensitive adhesive sheet consisting of a pressure-sensitive adhesive layer
  • the concept of adhesive sheet here may 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 in the form of a roll or a sheet. Alternatively, the adhesive sheet may be further processed into various shapes.
  • FIGS. 1 and 2 A configuration example of a double-sided adhesive type base material-less adhesive sheet (base material-less double-sided adhesive sheet) is shown in FIGS. 1 and 2.
  • the adhesive sheet 1 shown in FIG. 1 has a structure in which both surfaces 21A and 21B of the adhesive layer 21 without a base material are protected by release liners 31 and 32, respectively, with at least the adhesive layer side serving as a release surface.
  • the adhesive sheet 2 shown in FIG. 2 has a structure in which one surface (adhesive surface) 21A of the adhesive layer 21 without a base material is protected by a release liner 31 whose both surfaces are release surfaces.
  • the other surface (adhesive surface) 21B of the adhesive layer 21 comes into contact with the back surface of the release liner 31, so that the other surface 21B can also be protected by the release liner 31.
  • the technique disclosed herein is preferably implemented in the form of a base material-less adhesive sheet consisting of an adhesive layer from the viewpoint of flexibility that follows an adherend that is repeatedly folded.
  • the above-mentioned base material-less pressure-sensitive adhesive sheet is preferable also from the viewpoint of reducing the thickness of the pressure-sensitive adhesive sheet and increasing the transparency of the pressure-sensitive adhesive sheet.
  • the adhesive sheet disclosed herein may have a cross-sectional structure schematically shown in FIG. 3, for example.
  • the adhesive sheet 3 shown in FIG. 3 includes a support base material 10 and a first adhesive layer 21 and a second adhesive layer 22 supported on the first surface 10A and second surface 10B of the support base material 10, respectively. Be prepared.
  • the first surface 10A and the second surface 10B are both 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 (adhesive sheet with adhesive properties on both sides).
  • the first adhesive surface 21A and the second adhesive surface 22A are each protected by release liners 31 and 32, in which at least the adhesive surface side is a surface having releasability (release surface). It has a structure.
  • the release liner 32 may be omitted, and a release liner 31 having release surfaces on both sides may be used, and the adhesive sheet 3 may be wound to bring the second adhesive surface 22A into contact with the back surface of the release liner 31. Accordingly, the second adhesive surface 22A may also be protected by the release liner 31.
  • the technology disclosed herein is preferably implemented in the form of the above-mentioned double-sided pressure-sensitive adhesive sheet without a base material or with a base material for fixing and joining members (for example, optical members).
  • the adhesive sheet disclosed herein may be in the form of a single-sided adhesive sheet with a base material, which has an adhesive layer on only one side of a non-peelable base material (supporting base material).
  • An example of the form of a single-sided adhesive sheet is a form in which the structure shown in FIG. 3 does not include either the first adhesive layer 21 or the second adhesive layer 22.
  • the adhesive layer of the adhesive sheet disclosed herein can be formed by applying (for example, coating) an adhesive composition to a suitable surface and then curing the composition.
  • the adhesive composition can be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, and a 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 adhesive layer is suitably 5 ⁇ m or more, for example, 10 ⁇ m or more, 15 ⁇ m or more, 20 ⁇ m or more, 30 ⁇ m or more, 50 ⁇ m or more. It may be 70 ⁇ m or more or 85 ⁇ m or more. Adhesive strength tends to increase as the thickness of the adhesive layer increases. Further, in some embodiments, 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, may be 50 ⁇ m or less, or may be 30 ⁇ m or less. It may be advantageous that the thickness of the adhesive layer is not too large from the viewpoint of making the adhesive sheet thinner. Moreover, a thin adhesive layer tends to have excellent followability to an adherend.
  • the technology disclosed herein can be preferably carried out, for example, in an embodiment in which the thickness of the adhesive layer is 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 described above is at least the thickness of the first pressure-sensitive adhesive layer.
  • the thickness of the second adhesive layer may also be selected from a similar range.
  • the thickness of the adhesive sheet matches the thickness of the adhesive layer.
  • the haze value (sometimes simply referred to as "haze") of the adhesive layer constituting the adhesive sheet may be, for example, 5.0% or less, and may be 3.0% or less. It is preferably 2.0% or less, more preferably 1.0% or less, 0.9% or less, 0.8% or less, 0.5% or less, It may be 0.3% or less.
  • Adhesive sheets with highly transparent adhesive layers are used for applications that require high light transmittance (for example, optical applications), with or without a base material, and for applications where adherends can be attached through the adhesive sheet. It can be preferably applied to applications that require good visual recognition performance.
  • the lower limit of the haze value of the adhesive layer is not particularly limited, and from the viewpoint of improving transparency, the smaller the haze value is, the more preferable it is.
  • the haze value may be, for example, 0.05% or more, or 0.10% or more, taking into consideration the refractive index and adhesive properties.
  • the "haze value” refers to the ratio of diffusely transmitted light to the total transmitted light when visible light is irradiated onto the measurement target. Also called cloudiness value.
  • the haze value can be measured according to the method described in Examples below.
  • the haze value of the adhesive layer can be adjusted, for example, by selecting the composition, thickness, etc. of the adhesive layer.
  • the haze value of the adhesive sheet may be, for example, 10.0% or less, preferably 5.0% or less, more preferably 3.0% or less, and 2.0% or less. % or less, and may be 1.7% or less, 1.5% or less, 1.2% or less, 1.0% or less, or 0.8% or less.
  • Adhesive sheets with such high transparency 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 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 is, the more preferable it is.
  • the haze value may be, for example, 0.05% or more, 0.1% or more, or 0.2% or more, taking into account the refractive index and adhesive properties. It may be 0.3% or more.
  • the haze value of the pressure-sensitive adhesive sheet can be measured in the same manner as the measurement of 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, and the type and thickness of the base material in the case of a structure including a base material.
  • the total light transmittance of the adhesive layer is preferably 85.0% or more (for example, 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 is used for applications that require high light transmittance (for example, optical applications), with or without a base material, and for attaching an adherend through the pressure-sensitive adhesive sheet. It can be preferably applied to applications that require good visual recognition performance. In practical terms, the upper limit of the total light transmittance may be, for example, about 98% or less, about 96% or less, or about 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 product name "HAZEMETER HM-150" manufactured by Murakami Color Research Institute or its equivalent product is used.
  • the total light transmittance can be measured according to the method described in Examples below.
  • the total light transmittance of the adhesive layer can be adjusted, for example, by selecting the composition, thickness, etc. of the adhesive layer.
  • the total light transmittance of the adhesive sheet is preferably 85.0% or more (for example, 88.0% or more, 90.0% or more, or more than 90.0%).
  • Adhesive sheets with such high transparency 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 adhesive sheet.
  • the upper limit of the total light transmittance may be, for example, about 98% or less, about 96% or less, or about 95% or less.
  • the total light transmittance of the adhesive sheet may be about 94% or less, about 93% or less, or about 92% or less, taking into account the refractive index and adhesive properties.
  • the total light transmittance of the pressure-sensitive adhesive sheet can be measured in the same manner as the measurement of the total light transmittance of the pressure-sensitive 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, and the type and thickness of the base material in the case of a structure including 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 against a glass plate (peel strength against a glass plate) of, for example, 0.1 N/25 mm or more, and may be 0.5 N/25 mm or more.
  • the peel strength against the glass plate is 1.0 N/25 mm or more, more preferably 1.5 N/25 mm or more, even more preferably 2.0 N/25 mm or more, and 3.0 N/25 mm or more.
  • a pressure-sensitive adhesive sheet having a peel strength against a glass plate of a predetermined value or more is suitable for joining or fixing, for example, glass members.
  • 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 peel strength is measured after being pressure-bonded to an alkali glass plate as an adherend and left for 30 minutes in an environment of 23°C and 50% RH, and then at a peel angle of 180 degrees and a tensile speed of 300 mm/min. It can be understood by measuring.
  • the adhesive sheet to be measured can be reinforced with a suitable backing material (for example, a polyethylene terephthalate (PET) film with a thickness of about 25 ⁇ m to about 50 ⁇ m). More specifically, the peel strength can be measured according to the method described in the 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.
  • the thickness may be 50 ⁇ m or less.
  • the thickness of the adhesive sheet may be, for example, 5 ⁇ m or more, 10 ⁇ m or more, 25 ⁇ m or more, 30 ⁇ m or more, 40 ⁇ m or more, 80 ⁇ m or more, It may be 130 ⁇ m or more.
  • the thickness of the adhesive sheet refers to the thickness of the portion to be attached to the adherend.
  • the thickness refers to the thickness from the first adhesive surface 21A to the second adhesive surface 22A, and does not include the thickness of the release liners 31 and 32.
  • the pressure-sensitive adhesive sheet may be in the form of a pressure-sensitive adhesive sheet with a base material, which includes a pressure-sensitive adhesive layer on one or both sides of a supporting base material.
  • the material of the support base material is not particularly limited, and can be appropriately selected depending on the purpose and manner of use of the pressure-sensitive adhesive sheet.
  • 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), and polyethylene terephthalate (PET).
  • Plastic films such as polyester films whose main component is polyester such as phthalate (PEN), and polyvinyl chloride films whose main component is polyvinyl chloride; consisting of foams such as polyurethane foam, polyethylene (PE) foam, and polychloroprene foam.
  • Foam sheets; Woven and non-woven fabrics made of various fibrous materials can be natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, etc.
  • Examples include papers such as Japanese paper, high-quality paper, kraft paper, and crepe paper; metal foils such as aluminum foil and copper foil; and the like.
  • a base material having a composite structure of these materials may also be used. Examples of such composite base materials include base materials having a structure in which metal foil and the above-mentioned plastic film are laminated, and plastic base materials reinforced with inorganic fibers such as glass cloth.
  • the film base material may be a porous base material such as a foam film or a non-woven fabric sheet, or a non-porous base material, and may have a porous layer and a non-porous layer.
  • the base material may have a laminated structure.
  • the film base material may preferably include a base film that includes a (self-supporting or independent) resin film that can maintain its shape independently.
  • the term "resin film” refers to a resin film that has a non-porous structure and typically is substantially void-free. Therefore, the resin film is a concept that is distinguished from foam films and nonwoven fabrics.
  • the resin film one 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 aliphatic ring structure such as norbornene structure; polyamide (PA) such as nylon 6, nylon 66, and partially aromatic polyamide.
  • polyester polyolefin
  • 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); Fluororesin such as polytetrafluoroethylene (PTFE); Acrylic resin; Cellulose polymer such as triacetyl cellulose (TAC); Polyarylate; Polystyrene; Polyvinyl chloride; Polyvinylidene chloride Resins such as; can be used.
  • PI such as transparent polyimide (CPI); Polyamideimide (PAI); Polyetheretherketone (PEEK); Polyethersulfone (PES); Polyphenylene sulfide (PPS); Polycarbonate (PC); Polyurethane (PU); Ethylene-vinyl acetate copolymer (EVA); Fluororesin such as
  • the resin film may be formed using a resin material containing only one type of such resin, or may be formed using a resin material that is a blend of two or more types of resin. Good too.
  • the resin film may be unstretched or may be stretched (for example, uniaxially or biaxially stretched).
  • PET film, PBT film, PEN film, unoriented polypropylene (CPP) film, biaxially oriented polypropylene (OPP) film, low density polyethylene (LDPE) film, linear low density polyethylene (LLDPE) film, PP/PE Blend films, cycloolefin polymer (COP) films, CPI films, TAC films, etc. can be preferably used.
  • resin films preferable from the viewpoint of strength and dimensional stability include PET film, PEN film, PPS film, and PEEK film. PET film and PPS film are particularly preferred from the viewpoint of availability, and PET film is particularly preferred.
  • the resin film may contain known substances such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, slip agents, anti-blocking agents, etc., to the extent that the effects of the present invention are not significantly impaired. Additives may be added as necessary.
  • the blending amount of the additive is not particularly limited, and can be appropriately set depending on the use of the pressure-sensitive adhesive sheet.
  • the method for producing the resin film is not particularly limited.
  • conventionally known general resin film forming methods such as extrusion molding, inflation molding, T-die casting molding, and calender roll molding can be appropriately employed.
  • the base material may be substantially composed of such a base film.
  • the base material may include an auxiliary layer in addition to the base film.
  • auxiliary layers include optical property adjustment layers (e.g., colored layers, antireflection layers), printing layers and laminating layers to impart a desired appearance to the substrate, antistatic layers, undercoat layers, and release layers. Examples include surface treatment layers such as.
  • a light-transmitting base material (hereinafter also referred to as a light-transmitting base material) can be preferably employed as the supporting base material.
  • the total light transmittance of the light-transmitting base material may be, for example, more than 50%, and may be 70% or more.
  • the total light transmittance of the supporting substrate is 80% or more, more preferably 90% or more, and may be 95% or more (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 product name "HAZEMETER HM-150" manufactured by Murakami Color Research Institute or its equivalent product is used.
  • a preferred example of the above-mentioned light-transmitting base material is a light-transmitting resin film.
  • the light-transmitting substrate may be an optical film.
  • the thickness of the base material is not particularly limited, and can be selected depending on the purpose and manner of use of the pressure-sensitive 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 processability of the adhesive sheet, 150 ⁇ m or less, 100 ⁇ m or less, 50 ⁇ m or less, and 25 ⁇ m or less.
  • the thickness may be less than or equal to 10 ⁇ m.
  • the thickness of the base material may be, for example, 2 ⁇ m or more, 10 ⁇ m or more, or 25 ⁇ m or more.
  • the side of the base material on which the adhesive layer will be laminated may be treated with corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, or application of an undercoat (primer) to form an undercoat layer, as necessary.
  • Conventionally known surface treatments such as forming may be applied. Such surface treatment may be a treatment for improving the anchoring ability of the adhesive layer to the base material.
  • the composition of the primer used to form the undercoat layer is not particularly limited, and can be appropriately selected from known primers.
  • the thickness of the undercoat layer is not particularly limited, but it is usually about 0.01 ⁇ m to 1 ⁇ m, preferably about 0.1 ⁇ m to 1 ⁇ m.
  • Other treatments that may be applied to the base material as needed include antistatic layer formation treatment, colored layer formation treatment, printing treatment, and the like. These treatments can be applied alone or in combination.
  • the adhesive sheet disclosed herein can take the form of an adhesive product in which the surface (adhesive surface) of an adhesive layer is brought into contact with the release surface of a release liner. Therefore, this specification provides a pressure-sensitive adhesive sheet with a release liner (adhesive product) that includes any pressure-sensitive adhesive sheet disclosed herein and a release liner having a release surface that comes into contact with the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet. Ru.
  • the release liner is not particularly limited, and includes, for example, a release liner having a release layer on the surface of a liner base material such as a resin film or paper (paper laminated with a resin such as polyethylene), or a fluorine-based polymer.
  • a release liner made of a resin film made of a low adhesive material such as (polytetrafluoroethylene, etc.) or polyolefin resin (polyethylene, polypropylene, etc.) can be used. Since they have excellent surface smoothness, a release liner having a release layer on the surface of a resin film as a liner base material or a release liner made of a resin film made of a low adhesive material can be preferably employed.
  • the resin film is not particularly limited as long as it can protect the 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 agent can be used.
  • the adhesive sheet disclosed herein includes an adhesive that has both a high refractive index and flexibility, it can be utilized in various applications requiring a high refractive index and flexibility by taking advantage of its characteristics.
  • display devices image display devices
  • organic EL electroluminescent
  • PDP plasma display panels
  • electronic paper input devices such as touch panels, etc.
  • foldable displays and rollable displays it is preferably used as a means for joining, fixing, and protecting members having a high refractive index.
  • the adhesive sheet disclosed herein has a high refractive index and is flexible enough to withstand repeated bending operations, so it can be repeatedly folded while attached to a foldable display or rollable display. It is possible to follow the adherend (foldable display, etc.) well. Examples of objects to be pasted in such usage patterns include glass members such as window glasses and cover glasses used in foldable displays and rollable displays.
  • the adhesive sheet disclosed herein easily follows and adheres to curved surfaces such as three-dimensional shapes of portable electronic devices, so it is also suitable for use in electronic devices having such curved shapes.
  • the adhesive may have excellent heat resistance in addition to having a high refractive index and good flexibility.
  • the above-mentioned portable electronic device may be used in a high-temperature environment, and its internal space may become heated due to heat generated by electronic components, so the advantage of using the above-mentioned heat-resistant adhesive sheet is great.
  • Examples of the above-mentioned portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, and various wearable devices (e.g., wrist-wear devices that are worn on the wrist like watches, and devices that are attached to the body using clips, straps, etc.).
  • Eyewear types include modular types that are attached to the body, eyewear types (monocular and binocular types, including head-mounted types), clothing types that are attached to shirts, socks, hats, etc. in the form of accessories, and earphones. 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, in-vehicle information.
  • portable does not mean that it is simply portable; it also means that it has a level of portability that allows an individual (standard adult) to carry it relatively easily. shall mean.
  • the material to which the adhesive sheet disclosed herein is attached is not particularly limited, but includes, for example, copper, silver, gold, iron, tin, palladium, aluminum, nickel, titanium, Metal materials such as chromium, zinc, etc., or alloys containing two or more of these, such as polyimide resin, acrylic resin, polyether nitrile resin, polyether sulfone resin, polyester resin (PET resin, polyethylene naphthalate resins, etc.), polyvinyl chloride resins, polyphenylene sulfide resins, polyetheretherketone resins, polyamide resins (so-called aramid resins, etc.), polyarylate resins, polycarbonate resins, diacetyl cellulose and triacetyl cellulose.
  • Examples include various resin materials (typically plastic materials) such as cellulose polymers, vinyl butyral polymers, and liquid crystal polymers, and inorganic materials such as alumina, zirconia, alkali glass, alkali-free glass, quartz glass, and carbon.
  • the adhesive sheet disclosed herein can be used by being attached to a member (for example, an optical member) made of the above-mentioned material.
  • the member or material to which the adhesive sheet disclosed herein is attached is made of a material with a higher refractive index than a general acrylic adhesive.
  • the refractive index of the adherend material is, for example, 1.50 or more, and some adherend materials have a refractive index of 1.55 or more or 1.58 or more, and even have a refractive index of 1.62 or more (for example, 1.50 or more). .66) exists.
  • Such high refractive index adherend materials are typically resin materials. 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 adhesive sheet disclosed herein can be preferably exhibited.
  • 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 an embodiment in which it is attached to an adherend (for example, a member) having a high refractive index as described above.
  • a suitable example of such an adherend is a resin film having a refractive index of 1.50 to 1.80 (preferably 1.55 to 1.75, for example 1.60 to 1.70).
  • the refractive index can be measured in the same manner as the refractive index of the adhesive.
  • the member or material to which the adhesive sheet is attached may have light transmittance.
  • the total light transmittance of the adherend may be, for example, greater than 50%, preferably 70% or more.
  • the total light transmittance of the adherend is 80% or more, more preferably 90% or more, and may be 95% or more (for example, 95 to 100%).
  • the pressure-sensitive adhesive sheet disclosed herein can be preferably used in a mode where it is attached to an adherend (for example, an optical member) having a total light transmittance of a predetermined value or more.
  • the total light transmittance is measured using a commercially available transmittance meter in accordance with JIS K 7136:2000.
  • the transmittance meter the product name "HAZEMETER HM-150" manufactured by Murakami Color Research Institute or its equivalent product is used.
  • the adherend (for example, member) to which the pressure-sensitive adhesive sheet is attached may have the above-mentioned refractive index and the above-mentioned 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%
  • the pressure-sensitive adhesive sheet disclosed herein is preferably used in an embodiment in which it is attached to an adherend, such as a member (for example, 70% or more, preferably 80% or more, more preferably 90% or more, and even 95% or more). obtain.
  • the effects of the technique disclosed herein are particularly preferably exhibited in the embodiment in which the adhesive is attached to such a member.
  • the adhesive sheet disclosed herein is used, for example, as an optical pressure-sensitive adhesive sheet used for bonding optical members (for bonding optical members) or for manufacturing products (optical products) using the above-mentioned optical members.
  • a pressure-sensitive adhesive sheet can be preferably used.
  • the above-mentioned optical product may have a so-called polarizing plate-less configuration.
  • the optical product may be configured only of layers with a polarization degree of 80% or less on the viewing side from the light source (such as an organic EL panel).
  • the above-mentioned optical member refers to a member having optical properties (for example, polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffraction, optical rotation, visibility, etc.). say.
  • the above-mentioned optical member is not particularly limited as long as it has optical properties, but for example, it may be a member constituting a device (optical device) such as a display device (image display device) or an input device, or a member used in these devices.
  • Members include, for example, polarizing plates, wavelength plates, retardation plates, optical compensation films, brightness enhancement films, light guide plates, reflective films, antireflection films, hard coat (HC) films, shock 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 on which these are laminated (collectively referred to as (sometimes referred to as "functional film”).
  • the above-mentioned “plate” and “film” each include shapes such as plate, film, and sheet.
  • polarizing film includes “polarizing plate” and “polarizing sheet”, etc.
  • the “light guide plate” includes “light guide film”, “light guide sheet”, etc.
  • 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 an electronic paper. Moreover, a touch panel etc. are mentioned as said input device.
  • optical member is not particularly limited, but includes, for example, a member (for example, a sheet-like, film-like, or plate-like member) made of glass, acrylic resin, polycarbonate, PET, metal thin film, etc.
  • a member for example, a sheet-like, film-like, or plate-like member
  • optical member in this specification includes members (design films, decorative films, surface protection 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, waveguide, condensing, and diffraction, or a fluorescent film, etc., with other optical members ( It can be preferably used for bonding to other optical films.
  • an optical film such as a film having one or more functions such as light transmission, reflection, diffusion, waveguide, condensing, and diffraction, or a fluorescent film, etc.
  • other optical members It can be preferably used for bonding to other optical films.
  • bonding optical films that have at least one of the functions of light waveguide, condensation, and diffraction it is desirable that the entire bulk of the bonding layer has a high refractive index, and the technology disclosed herein is preferably applied. Can be targeted.
  • 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.
  • optical films such as light guide films, diffusion films, fluorescent films, toning films, prism sheets, lenticular films, and microlens array films.
  • the adhesive disclosed herein can be preferably used as an adhesive that can meet such demands. More specifically, for example, when bonding a light guide film or a diffusion film, adjusting the refractive index (for example, increasing the refractive index) of the adhesive layer as a bonding layer can contribute to thinning.
  • light extraction efficiency (which can also be understood as luminous efficiency) can be improved by appropriately adjusting the refractive index difference between the fluorescent emitter and the adhesive.
  • the refractive index of the adhesive when bonding color toning films, by appropriately adjusting the refractive index of the adhesive so that the difference in refractive index with the color toning pigment is reduced, scattering components can be reduced, contributing to improved light transmittance.
  • appropriately adjusting the refractive index of the adhesive can control light diffraction and contribute to improving brightness and/or viewing angle.
  • the pressure-sensitive adhesive sheet disclosed herein is preferably used in an embodiment in which it is attached to a high refractive index adherend (which may be a high refractive index layer or member, etc.), and reduces interface reflection with the adherend. Can be suppressed.
  • the pressure-sensitive adhesive sheet used in this embodiment preferably has a small refractive index difference with the adherend and high adhesion at the interface with the adherend, as described above. Further, from the viewpoint of improving the homogeneity of the appearance, it is preferable that the thickness of the adhesive layer is highly uniform, for example, it is preferable that the surface smoothness of the adhesive surface is high.
  • the thickness of the adherend with a high refractive index is relatively small (for example, 5 ⁇ m or less, 4 ⁇ m or less, or 2 ⁇ m or less), it is necessary to It is particularly useful to suppress reflexes.
  • a polarizing plate with a retardation layer that includes a polarizer, a first retardation layer, and a second retardation layer in this order bonding of the polarizer and the first retardation layer and/or Another example is an embodiment used for bonding the first retardation layer and the second retardation layer.
  • the adhesive sheet disclosed herein is suitable for increasing the refractive index, it is preferably attached to a light emitting layer of an optical semiconductor or the like (for example, a high refractive light emitting layer mainly composed of an inorganic material). can be used. By reducing the difference in refractive index between the light emitting layer and the adhesive layer, reflection at the interface between them can be suppressed and light extraction efficiency can be improved.
  • the pressure-sensitive adhesive sheet used in this embodiment preferably includes a pressure-sensitive adhesive layer with a high refractive index. Further, from the viewpoint of improving brightness, it is preferable that the pressure-sensitive adhesive sheet has low coloring. This can also be advantageous from the viewpoint of suppressing unintentional coloring caused by the pressure-sensitive adhesive sheet.
  • a self-luminous element means a light-emitting element whose luminance can be controlled by the value of a flowing current.
  • the self-luminous element may be composed of a single unit or an aggregate.
  • Specific examples of self-luminous elements include, but are not limited to, light emitting diodes (LEDs) and organic EL.
  • a light-emitting device means a device including such a self-luminous element as a component. Examples of the light emitting device include, but are not limited to, a light source module device used for illumination (for example, a planar light emitting module) and a display device in which pixels are formed.
  • the adhesive disclosed herein can be used in microlenses and other lens members used as constituent members of cameras, light emitting devices, etc. (for example, microlenses constituting microlens array films, 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, It can be preferably used as such. Since 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 high refractive index resin or lenses having a surface layer made of high refractive index resin).
  • the adhesive disclosed herein can also be used as a lens resin by itself, for example in the form of being filled in the recesses or voids of a suitable transparent member.
  • the mode of bonding optical members together using the adhesive sheet disclosed herein is not particularly limited, but includes, for example, (1) a mode of bonding optical members together via the pressure-sensitive adhesive sheet disclosed herein; )
  • the optical member may be attached to a member other than the optical member via the adhesive sheet disclosed herein, or (3) the adhesive sheet disclosed herein may include an optical member and the optical member may be attached to a member other than the optical member.
  • the adhesive sheet may be attached to an optical member or a member other than an optical member.
  • 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).
  • a pressure-sensitive adhesive sheet that includes an optical member as a support in this manner can also be understood as a pressure-sensitive adhesive optical member (for example, a pressure-sensitive adhesive optical film).
  • a pressure-sensitive adhesive optical member for example, a pressure-sensitive adhesive optical film.
  • the adhesive sheet disclosed herein is a type of adhesive sheet having a support and the functional film is used as the support
  • the adhesive sheet disclosed herein is a type of adhesive sheet having a support
  • the adhesive sheet disclosed herein is a type of adhesive sheet having a support
  • the adhesive sheet disclosed herein is a type of adhesive sheet having a support.
  • 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 adhesive sheet is attached may have the refractive index of the adherend material described above.
  • the difference between the refractive index of the adhesive sheet and the refractive index of the member may be the refractive index difference between the adherend and the adhesive sheet described above.
  • the members constituting the laminate are the same as those described above as the members, materials, and adherends, so duplicate explanations will not be repeated.
  • the refractive index is 1.50 or more, and An adhesive having a ratio of storage elastic modulus G'(25°C) [Pa] at 25°C to elongation at break E B [%] (G'(25°C)/E B ) of 1 to 50.
  • the adhesive according to [1] or [2] above, wherein the storage modulus G' (25° C.) is within the range of 1.0 ⁇ 10 4 to 1.0 ⁇ 10 6 .
  • a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive according to any one of [1] to [4] above.
  • a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive according to any one of [1] to [4] and [10] to [19] above.
  • Example 1> (Preparation of polymer solution)
  • BA n-butyl acrylate
  • m-phenoxybenzyl acrylate manufactured by Kyoeisha Chemical Co., Ltd., trade name "Light"
  • acrylate POB-A refractive index: 1.566.
  • POB-A 25 parts and 1 part of 4-hydroxybutyl acrylate (4HBA), 2,2'-azobis as a polymerization initiator.
  • Example 2 A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 1 except that the amount of 6MDNTM used was changed to 70 parts with respect to 100 parts of polymer P1.
  • a pressure-sensitive adhesive sheet according to this example (base material-less double-sided pressure-sensitive adhesive sheet consisting of a 50 ⁇ m thick pressure-sensitive adhesive layer) was produced in the same manner as in Example 1 except that this pressure-sensitive adhesive composition was used.
  • Example 3 A solution of polymer P2 (polymer concentration 40%) was prepared in the same manner as in the preparation of the polymer solution in Example 1, except that the composition of the monomer components was changed to 74 parts of 2-ethylhexyl acrylate (2EHA), 25 parts of POB-A, and 1 part of 4HBA. was prepared. The Mw of polymer P2 was 1 million.
  • a pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 1 except that a solution of polymer P2 was used instead of a solution of polymer P1.
  • a pressure-sensitive adhesive sheet according to this example base material-less double-sided pressure-sensitive adhesive sheet consisting of a 50 ⁇ m thick pressure-sensitive adhesive layer) was produced in the same manner as in Example 1 except that this pressure-sensitive adhesive composition was used.
  • Example 4 A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 3, except that the amount of 6MDNTM used was changed to 70 parts with respect to 100 parts of polymer P2.
  • a pressure-sensitive adhesive sheet according to this example (base material-less double-sided pressure-sensitive adhesive sheet consisting of a pressure-sensitive adhesive layer having a thickness of 50 ⁇ m) was produced in the same manner as in Example 1 except that this pressure-sensitive adhesive composition was used.
  • Example 5 A solution of polymer P3 (polymer concentration 40 %) were prepared. The Mw of polymer P3 was 1 million.
  • a pressure-sensitive adhesive composition according to this example was prepared in the same manner as the pressure-sensitive adhesive composition in Example 1 except that a solution of polymer P3 was used instead of a solution of polymer P1.
  • a pressure-sensitive adhesive sheet according to this example (base material-less double-sided pressure-sensitive adhesive sheet consisting of a pressure-sensitive adhesive layer having a thickness of 50 ⁇ m) was produced in the same manner as in Example 1 except that this pressure-sensitive adhesive composition was used.
  • a solution of polymer P4 (polymer concentration 40%) was prepared in the same manner as in the preparation of the polymer solution in Example 1, except that the composition of the monomer components was changed to 99 parts BA and 1 part 4HBA.
  • the Mw of polymer P4 was 1.5 million.
  • a pressure-sensitive adhesive composition according to this example was prepared in the same manner as in the preparation of the pressure-sensitive adhesive composition in Example 2, except that a solution of polymer P4 was used instead of a solution of polymer P1.
  • the adhesive sheet according to this example (based on the adhesive layer) was prepared in the same manner as in Example 1, except that the amount of application was adjusted so that an adhesive layer with a thickness of 20 ⁇ m was formed.
  • a material-less double-sided adhesive sheet) was produced.
  • Example 7 A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 6, except that the amount of 6MDNTM used was changed to 60 parts with respect to 100 parts of polymer P4.
  • a pressure-sensitive adhesive sheet according to this example (base material-less double-sided pressure-sensitive adhesive sheet consisting of a 20 ⁇ m thick pressure-sensitive adhesive layer) was produced in the same manner as in Example 6 except that this pressure-sensitive adhesive composition was used.
  • Example 8 to Example 10 In the preparation of the adhesive composition in Example 6, 6-acryloyloxymethyldinaphthothiophene (6MDNTA, refractive index: 1.737) was used in Example 8 and 6-acryloyloxyethyldinaphthothiophene (6MDNTA, refractive index: 1.737) in Example 9, in place of 6MDNTM. 6EDNTA, refractive index: 1.722), and in Example 10 42 parts of 6-ethyldinaphthothiophene (6EDNT, refractive index: 1.764) were used per 100 parts of polymer P4.
  • the pressure-sensitive adhesive compositions of each example were prepared in the same manner as in the preparation of the pressure-sensitive adhesive composition in Example 6 except for the above.
  • a pressure-sensitive adhesive sheet (substrate-less double-sided pressure-sensitive adhesive sheet consisting of a pressure-sensitive adhesive layer having a thickness of 50 ⁇ m) according to each example was produced in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive composition was used.
  • Example 11 A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in Example 8 except that 6MDNTA was not used.
  • a pressure-sensitive adhesive sheet according to this example (base material-less double-sided pressure-sensitive adhesive sheet consisting of a 50 ⁇ m thick pressure-sensitive adhesive layer) was produced in the same manner as in Example 1 except that this pressure-sensitive adhesive composition was used.
  • Example 12 In preparing the adhesive composition in Example 8, 42 parts of 2,12-diallyloxydinaphthothiophene (2,12-DAODNT, refractive index: 1.729) was added to 100 parts of polymer P4 in place of 6MDNTA. used. A pressure-sensitive adhesive composition according to this example was prepared in the same manner as in the preparation of the pressure-sensitive adhesive composition in Example 8 except for the above. A pressure-sensitive adhesive sheet according to this example (substrate-less double-sided pressure-sensitive adhesive sheet consisting of a pressure-sensitive adhesive layer having a thickness of 50 ⁇ m) was produced in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive composition was used.
  • Example 13 A solution of polymer P5 (polymer concentration 40%) was prepared in the same manner as in the preparation of the polymer solution in Example 1, except that the composition of the monomer components was changed to 95 parts of POB-A and 5 parts of 4HBA. The Mw of polymer P5 was 500,000. The above solution of polymer P5 (polymer concentration 40%) was diluted with ethyl acetate to a polymer concentration of 20%.
  • the adhesive sheet according to this example (based on an adhesive layer) was prepared in the same manner as in Example 1, except that the amount of application was adjusted so that an adhesive layer with a thickness of 25 ⁇ m was formed. A material-less double-sided adhesive sheet) was produced.
  • each substituted DNT used in Examples 1 to 10, 12, and 13 are shown in Table 1.
  • 2,12-DAODNT is a compound with a line symmetric structure, and the others are compounds with an asymmetric structure.
  • the refractive index of these compounds was measured by the following method. That is, a 5% ethyl acetate solution or a 5% MEK solution of the compound to be measured was applied onto a glass plate so that the dry film thickness was 10 ⁇ m, and was dried by heating at 130° C. for 5 minutes.
  • the refractive index of the target compound thus formed on the glass plate was measured using a prism coupler (manufactured by Metricon, model "2010M”) under conditions of a measurement temperature of 25° C. and a measurement wavelength of 594 nm.
  • the refractive index of the adhesive layer (substrate-less double-sided adhesive sheet) according to each example was measured using a prism coupler (manufactured by Metricon, model "2010M") under conditions of a measurement temperature of 25° C. and a measurement wavelength of 594 nm.
  • the adhesive layers according to each example were laminated to have a thickness of approximately 1.5 mm, and a disk-shaped sample having a diameter of 7.9 mm was punched out to be used as a measurement sample.
  • Dynamic viscoelasticity measurements were performed using the "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific under the following conditions. From the measurement results, the storage elastic modulus G' [Pa] of the adhesive at each temperature (-20°C, 25°C and 60°C) was determined.
  • the temperature corresponding to the peak top temperature of the loss tangent tan ⁇ (loss modulus G"/storage modulus G') in the dynamic viscoelasticity measurement was determined as the glass transition temperature (Tg) [° C.] of the adhesive.
  • Tg glass transition temperature [° C.] of the adhesive.
  • the adhesive layer (substrate-less double-sided adhesive sheet) according to each example was cut into a size of 30 mm in length and X mm in width while being sandwiched between PET films (release liners) R1 and R2.
  • the width Xmm was set according to the thickness of the adhesive layer so that the cross-sectional area of the adhesive layer in the cross section along the width direction was approximately 2 mm 2 .
  • one release liner is removed to expose one surface of the adhesive layer, and the adhesive layer is wound up on the other release liner with its length direction as an axis to form a cylindrical column with a length of 30 mm.
  • a sample was prepared.
  • Total light transmittance and haze Using a test piece in which the adhesive layer according to each example was attached to alkali-free glass (thickness 0.8 to 1.0 mm, total light transmittance 92%, haze 0.4%), under a measurement environment of 23 ° C.
  • the total light transmittance and haze of the test piece were measured using a haze meter ("HM-150" manufactured by Murakami Color Research Institute).
  • the values obtained by subtracting the total light transmittance and haze of the alkali-free glass from the measured values were defined 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 50 ⁇ m thick PET film was pasted and lined, and then cut into a size of 25 mm in width and 100 mm in length. was used as the test piece.
  • the release liner on the other side was peeled off from the test piece, and a 2 kg roller was moved back and forth on the surface of an alkali glass plate (manufactured by Matsunami Glass Industries Co., Ltd., thickness 1.35 mm, blue plate edge polished) as an adherend. I crimped it.
  • peel strength adhesive strength [N/25mm] was measured.
  • "Tensile and Compression Tester, TG-1kN” manufactured by Minebea was used as a universal tension and compression tester.
  • backing with PET film is not essential.
  • Table 2 shows an overview and evaluation results of the adhesives for each example.
  • the adhesives of Examples 1 to 10 achieve a ratio (G'(25°C)/E B ) ⁇ 50 due to low elastic modulus and high elongation deformability at 25°C, and have a high refractive index. It struck a good balance between flexibility and suppleness.
  • the adhesive layers (substrate-less adhesive sheets) according to these examples had high transparency and exhibited good adhesion to glass when pressure bonded at room temperature.
  • the adhesive of Example 11 had a low refractive index
  • the adhesives of Examples 12 and 13 had a high ratio (G'(25°C)/ EB ) and lacked flexibility.
  • the adhesive of Example 12 was cloudy and the refractive index could not be measured.
  • the solubility of each substituted DNT used as an additive in Examples 1 to 10 in ethyl acetate was 6EDNTA>6MDNTM>6MDNTA>6EDNT.
  • the solubility of 2,12-DAODNT in ethyl acetate was comparable to that of 6MDNTA.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Developing Agents For Electrophotography (AREA)
  • Polarising Elements (AREA)
  • Adhesive Tapes (AREA)

Abstract

L'invention concerne un adhésif sensible à la pression combinant un indice de réfraction élevé avec une flexibilité. L'adhésif sensible à la pression a un indice de réfraction supérieur ou égal à 1,50 et un rapport entre le module de stockage à 25 °C G'(25 °C) [Pa] et l'allongement à 25 °C à la rupture Eb [%], G'(25 °C)/Eb, de 1 à 50.
PCT/JP2023/024973 2022-07-08 2023-07-05 Adhésif sensible à la pression et feuille adhésive sensible à la pression Ceased WO2024010042A1 (fr)

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WO2024157790A1 (fr) * 2023-01-23 2024-08-02 三菱ケミカル株式会社 Feuille adhésive, feuille adhésive avec film de démoulage, stratifié pour dispositif d'affichage d'image, et dispositif d'affichage d'image souple
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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WO2021193724A1 (fr) * 2020-03-24 2021-09-30 日東電工株式会社 Composition adhésive sensible à la pression, adhésif sensible à la pression et feuille adhésive sensible à la pression
WO2021193721A1 (fr) * 2020-03-24 2021-09-30 日東電工株式会社 Dispositif électroluminescent

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WO2021193724A1 (fr) * 2020-03-24 2021-09-30 日東電工株式会社 Composition adhésive sensible à la pression, adhésif sensible à la pression et feuille adhésive sensible à la pression
WO2021193721A1 (fr) * 2020-03-24 2021-09-30 日東電工株式会社 Dispositif électroluminescent

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