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WO2020045067A1 - Film de renforcement - Google Patents

Film de renforcement Download PDF

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Publication number
WO2020045067A1
WO2020045067A1 PCT/JP2019/031726 JP2019031726W WO2020045067A1 WO 2020045067 A1 WO2020045067 A1 WO 2020045067A1 JP 2019031726 W JP2019031726 W JP 2019031726W WO 2020045067 A1 WO2020045067 A1 WO 2020045067A1
Authority
WO
WIPO (PCT)
Prior art keywords
pressure
sensitive adhesive
adhesive layer
reinforcing film
adherend
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2019/031726
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English (en)
Japanese (ja)
Inventor
賢一 片岡
武史 仲野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nitto Denko Corp
Original Assignee
Nitto Denko Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nitto Denko Corp filed Critical Nitto Denko Corp
Priority to CN201980056630.1A priority Critical patent/CN112601796B/zh
Publication of WO2020045067A1 publication Critical patent/WO2020045067A1/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
    • C09J7/20—Adhesives in the form of films or foils characterised by their 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
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • 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
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature

Definitions

  • the present invention relates to a reinforcing film attached to a device surface.
  • An adhesive film may be attached to the surface of an optical device or an electronic device such as a display for the purpose of protecting the surface or imparting impact resistance.
  • Such an adhesive film usually has an adhesive layer fixedly laminated on a main surface of a film substrate, and is bonded to a device surface via the adhesive layer.
  • Patent Document 2 discloses an adhesive film that is used while being attached to a device surface when the device is used, in addition to assembling, processing, and transporting the device.
  • Such an adhesive film has a function of reinforcing the device by dispersing impact on the device and imparting rigidity to the flexible device, in addition to surface protection.
  • Patent Document 3 discloses a pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) that has low tackiness immediately after lamination with an adherend and is designed so that the adhesive force increases with time.
  • the pressure-sensitive adhesive film having such a pressure-sensitive adhesive layer fixedly laminated on a film substrate is easily peeled off from the adherend immediately after lamination with the adherend, and after a predetermined time elapses, the adhesive film Since it adheres firmly, it can be used as a reworkable reinforcing film.
  • Adhesive films to be bonded to the device surface must be free of air bubbles during bonding and have excellent workability in bonding, and should be able to be easily peeled off (reworked) if bonding failure occurs.
  • Can be Reinforcement films whose adhesive strength to an adherend changes with time can be easily reworked immediately after lamination, but are not sufficiently flexible with respect to the lead time of the process.
  • a reinforcing film having a pressure-sensitive adhesive layer whose adhesive strength increases with time, after bonding with an adherend, within a predetermined time until the adhesive strength increases, inspects the bonded state and performs rework. There is a need.
  • the reinforcing film is attached to the entire surface of the device or device component and then the processing such as removing the reinforcing film from a part of the area is performed, it is necessary to perform the processing until the adhesive strength increases. is there.
  • the present invention is excellent in the bonding property with the adherend, and after bonding with the adherend, it is possible to arbitrarily set the time until the adhesive strength is improved, and by improving the adhesive strength.
  • An object of the present invention is to provide a reinforcing film capable of firmly adhering to an adherend.
  • the reinforcing film of the present invention includes a pressure-sensitive adhesive layer fixedly laminated on one main surface of a film substrate.
  • the pressure-sensitive adhesive layer is composed of a photocurable composition containing a base polymer, a photocuring agent and a photopolymerization initiator.
  • a base polymer of the pressure-sensitive adhesive layer for example, an acrylic polymer is used.
  • the base polymer contains, as a monomer unit, a hydroxy group-containing monomer and / or a carboxy group-containing monomer, and a crosslinking agent such as a polyfunctional isocyanate compound or a polyfunctional epoxy compound is bonded to these functional groups to form a crosslinked structure. Is introduced.
  • the photocuring agent is a monomer or oligomer having two or more polymerizable functional groups, and a polyfunctional (meth) acrylate or the like is used.
  • the molecular weight of the photocuring agent is preferably 1500 or less.
  • the functional group equivalent of the photocuring agent is preferably about 100 to 500 g / eq.
  • the amount of the photocuring agent in the photocurable composition constituting the pressure-sensitive adhesive layer is preferably from 10 to 50 parts by weight based on 100 parts by weight of the base polymer.
  • the reinforcing film preferably has a wetting rate for the glass plate of 0.3 cm 2 / sec to 4 cm 2 / sec.
  • the reinforcing film before the photocuring of the pressure-sensitive adhesive layer preferably has an adhesive force to an adherend such as a glass plate of 0.03 N / 25 mm or more and less than 1 N / 25 mm. It is preferable that the adhesive strength of the reinforcing film after the photocuring of the pressure-sensitive adhesive layer to an adherend such as a glass plate is 1 N / 25 mm or more.
  • the adhesive layer is made of a photocurable composition, and the adhesive strength to the adherend is increased by photocuring the adhesive layer after the adhesion to the adherend.
  • the adhesive strength to the adherend is increased by photocuring the adhesive layer after the adhesion to the adherend.
  • rework is easy because the adhesive force with the adherend is small.
  • it has an appropriate wetting rate with respect to an adherend such as glass, it is excellent in bonding workability.
  • the pressure-sensitive adhesive after photo-curing shows high adhesive strength, it is expected that the reinforcement of the device and the improvement of reliability can be expected by bonding a reinforcing film.
  • the photocurable pressure-sensitive adhesive can arbitrarily set the timing of curing after lamination with the adherend, and thus the reinforcing film of the present invention can flexibly respond to the lead time of the process.
  • FIG. 1 is a cross-sectional view illustrating one embodiment of a reinforcing film.
  • the reinforcing film 10 includes an adhesive layer 2 on one main surface of the film substrate 1.
  • the pressure-sensitive adhesive layer 2 is fixedly laminated on one main surface of the film substrate 1.
  • the pressure-sensitive adhesive layer 2 is a photocurable pressure-sensitive adhesive made of a photocurable composition, and is cured by irradiation with actinic rays such as ultraviolet rays, so that the adhesive strength to an adherend increases.
  • FIG. 2 is a cross-sectional view of the reinforcing film in which the separator 5 is temporarily attached on the main surface of the pressure-sensitive adhesive layer 2.
  • FIG. 3 is a cross-sectional view showing a state in which the reinforcing film 10 is attached to the surface of the device 20.
  • the separator 5 is peeled off from the surface of the pressure-sensitive adhesive layer 2 and the exposed surface of the pressure-sensitive adhesive layer 2 is bonded to the surface of the device 20 as an adherend, whereby the reinforcing film 10 is bonded to the surface of the device 20. .
  • the pressure-sensitive adhesive layer 2 has not been cured yet, and the reinforcing film 10 (pressure-sensitive adhesive layer 2) has been temporarily attached to the device 20.
  • the reinforcing film 10 pressure-sensitive adhesive layer 2
  • the adhesive force at the interface between the device 20 and the pressure-sensitive adhesive layer 2 is increased, and the device 20 and the reinforcing film 10 are fixed.
  • “Fixed” refers to a state in which two laminated layers are firmly adhered to each other and separation at the interface between them is impossible or difficult. "Temporary adhesion” is a state in which the adhesive strength between the two laminated layers is small and the two layers can be easily peeled off at the interface between them.
  • the film substrate 1 and the adhesive layer 2 are fixed, and the separator 5 is temporarily attached to the adhesive layer 2.
  • the separator 5 is temporarily attached to the adhesive layer 2.
  • the device 20 and the pressure-sensitive adhesive layer 2 are in a temporarily attached state before the light-curing of the pressure-sensitive adhesive layer 2.
  • the film substrate 1 and the device 20 are separated, separation occurs at the interface between the pressure-sensitive adhesive layer 2 and the device 20, and the state in which the pressure-sensitive adhesive layer 2 is fixed on the film substrate 1 is maintained. Since no adhesive remains on the device 20, rework is easy.
  • the adhesive force between the pressure-sensitive adhesive layer 2 and the device 20 increases, so that it is difficult to peel the film substrate 1 from the device 20. May cause cohesive failure.
  • the film substrate 1 a plastic film is used. In order to fix the film substrate 1 and the pressure-sensitive adhesive layer 2, it is preferable that the surface of the film substrate 1 provided with the pressure-sensitive adhesive layer 2 is not subjected to a release treatment.
  • the thickness of the film substrate is, for example, about 4 to 500 ⁇ m.
  • the thickness of the film substrate 1 is preferably 12 ⁇ m or more, more preferably 30 ⁇ m or more, and even more preferably 45 ⁇ m or more.
  • the thickness of the film substrate 1 is preferably 300 ⁇ m or less, more preferably 200 ⁇ m or less.
  • compressive strength of the film substrate 1 is preferably 100 ⁇ 3000kg / cm 2, more preferably 200 ⁇ 2900kg / cm 2, 300 ⁇ 2800kg / cm 2 and more It is particularly preferably 400 to 2700 kg / cm 2 .
  • the plastic material constituting the film substrate 1 examples include a polyester resin, a polyolefin resin, a cyclic polyolefin resin, a polyamide resin, a polyimide resin, polyetheretherketone, and polyethersulfone.
  • the film substrate 1 is preferably a transparent film.
  • the actinic light is irradiated from the side of the film substrate 1 to cure the pressure-sensitive adhesive layer 2, the film substrate 1 may have transparency to actinic light used for curing the pressure-sensitive adhesive layer 2. preferable.
  • Polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferably used because they have both mechanical strength and transparency.
  • the adherend When irradiating actinic rays from the adherend side, the adherend only needs to have transparency to actinic rays, and the film substrate 1 may not be transparent to actinic rays.
  • the surface of the film substrate 1 may be provided with a functional coating such as an easy adhesion layer, an easy slip layer, a release layer, an antistatic layer, a hard coat layer, and an antireflection layer.
  • a functional coating such as an easy adhesion layer, an easy slip layer, a release layer, an antistatic layer, a hard coat layer, and an antireflection layer.
  • a release layer is not provided on the surface of the film substrate 1 where the pressure-sensitive adhesive layer 2 is provided.
  • the pressure-sensitive adhesive layer 2 fixed and laminated on the film substrate 1 is made of a photocurable composition containing a base polymer, a photocuring agent and a photopolymerization initiator. Since the pressure-sensitive adhesive layer 2 has a small adhesive force with an adherend such as a device or a device component before light curing, rework is easy. Since the pressure-sensitive adhesive layer 2 improves the adhesive strength to the adherend by light curing, the reinforcing film is hardly peeled off from the device surface even when the device is used, and is excellent in adhesion reliability.
  • the photocurable pressure-sensitive adhesive hardly hardens in a general storage environment, and is hardened by irradiation with actinic rays such as ultraviolet rays. Therefore, the reinforcing film of the present invention has an advantage that the curing timing of the pressure-sensitive adhesive layer 2 can be arbitrarily set, and the lead time of the process can be flexibly accommodated.
  • Wetting rate is preferably more than 0.3 cm 2 / s for glass reinforcing film, more preferably at least 0.35 cm 2 / sec, 0.4 cm more preferably more than 2 / s, particularly preferably at least 0.45 cm 2 / sec .
  • the wetting speed is from the state in which the pressure-sensitive adhesive layer at one end in the longitudinal direction of the test piece having a width of 25 mm x the length of 150 mm is brought into contact with the glass plate, and the pressure-sensitive adhesive layer of the test piece is brought into contact with the glass plate in the longitudinal direction.
  • a pressure-sensitive adhesive layer (photocurable composition) having a high wetting rate is likely to have poor appearance due to bleed-out of the photocurable agent.
  • the pressure-sensitive adhesive layer having a large wetting rate has a surface close to a liquid state and may have poor initial adhesion to an adherend such as glass, and the compatibility of the composition is low. Even if it is performed, the adhesiveness may not be sufficiently increased. Therefore, wetting rate for the glass of the reinforcement film is preferably 4 cm 2 / sec or less, 3.5 cm, more preferably less than 2 / sec, more preferably 3 cm 2 / sec or less, particularly preferably 2.5 cm 2 / sec.
  • the reinforcing film before the pressure-sensitive adhesive layer 2 is cured with respect to the glass plate.
  • the adhesive strength is preferably less than 1 N / 25 mm, more preferably 0.8 N / 25 mm or less, further preferably 0.7 N / 25 mm or less, and particularly preferably 0.6 N / 25 mm or less.
  • the adhesive strength of the reinforcing film to the glass plate is preferably at least 0.03 N / 25 mm, more preferably at least 0.05 N / 25 mm, 0.1 N / 25 mm or more is more preferable, and 0.2 N / 25 mm or more is particularly preferable.
  • the adhesive strength of the reinforcing film after photocuring the pressure-sensitive adhesive layer 2 to the glass plate is preferably 1 N / 25 mm or more, more preferably 2 N / 25 mm or more, and more preferably 3 N / 25 mm or more. Is more preferred.
  • the adhesive strength after photocuring the pressure-sensitive adhesive layer 2 is preferably twice or more, more preferably three times or more, and even more preferably five times or more the adhesive strength before the photocurable pressure-sensitive adhesive layer 2 is cured.
  • the thickness of the pressure-sensitive adhesive layer 2 is, for example, about 1 to 300 ⁇ m. As the thickness of the pressure-sensitive adhesive layer 2 increases, the adhesiveness to an adherend tends to improve. On the other hand, when the thickness of the pressure-sensitive adhesive layer 2 is excessively large, the fluidity before photo-curing is high, and handling may be difficult. Therefore, the thickness of the pressure-sensitive adhesive layer 2 is preferably 5 to 100 ⁇ m, more preferably 8 to 50 ⁇ m, still more preferably 10 to 40 ⁇ m, and particularly preferably 13 to 30 ⁇ m.
  • the total light transmittance of the pressure-sensitive adhesive layer 2 is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more.
  • the haze of the pressure-sensitive adhesive layer 2 is preferably 2% or less, more preferably 1% or less, further preferably 0.7% or less, and particularly preferably 0.5% or less.
  • the pressure-sensitive adhesive layer 2 is a photocurable composition containing a base polymer, a photocuring agent, and a photopolymerization initiator. From the viewpoint of setting the adhesiveness and the wetting rate of the pressure-sensitive adhesive layer 2 before the photocuring to an appropriate range, it is preferable that a crosslinked structure is introduced into the base polymer.
  • the base polymer is a main component of the pressure-sensitive adhesive composition.
  • the type of the base polymer is not particularly limited, and an acrylic polymer, a silicone polymer, a urethane polymer, a rubber polymer, or the like may be appropriately selected.
  • the pressure-sensitive adhesive composition preferably contains an acrylic polymer as a base polymer because of its excellent optical transparency and adhesiveness, and easy control of the adhesiveness, and 50% by weight of the pressure-sensitive adhesive composition. % Or more is preferably an acrylic polymer.
  • acrylic polymer those containing an alkyl (meth) acrylate as a main monomer component are preferably used.
  • (meth) acryl means acryl and / or methacryl.
  • alkyl (meth) acrylate an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms is preferably used.
  • the alkyl group of the alkyl (meth) acrylate may be straight-chain or branched.
  • alkyl (meth) acrylate examples include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, ( T-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2- (meth) acrylate Ethylhexyl, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl
  • the content of the alkyl (meth) acrylate is preferably 40% by weight or more, more preferably 50% by weight or more, even more preferably 55% by weight or more based on the total amount of the monomer components constituting the base polymer.
  • the acrylic base polymer preferably contains a monomer component having a crosslinkable functional group as a copolymer component.
  • the monomer having a crosslinkable functional group include a hydroxy group-containing monomer and a carboxy group-containing monomer.
  • the acrylic base polymer may have both a hydroxy group-containing monomer and a carboxy group-containing monomer as monomer components, or may have only one of them.
  • the hydroxy group or carboxy group of the base polymer becomes a reaction point with a crosslinking agent described later.
  • an epoxy crosslinking agent When an epoxy crosslinking agent is used, it is preferable to contain a carboxy group-containing monomer as a copolymer component of the base polymer.
  • a crosslinked structure By introducing a crosslinked structure into the base polymer, the cohesive force is improved, the adhesive force of the pressure-sensitive adhesive layer 2 is improved, and adhesive residue on the adherend during rework tends to be reduced.
  • Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and (meth) acrylate.
  • Examples thereof include 8-hydroxyoctyl acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and 4- (hydroxymethyl) cyclohexylmethyl (meth) acrylate.
  • carboxy group-containing monomer examples include (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like.
  • the total amount of the hydroxy group-containing monomer and the carboxy group-containing monomer relative to the total amount of the constituent monomer components is preferably 1 to 30% by weight, more preferably 3 to 25% by weight, and more preferably 5 to 25% by weight. More preferably, it is 20% by weight.
  • the acrylic base polymer has N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-acryloylmorpholine as constituent monomer components. , N-vinylcarboxylic acid amides, N-vinylcaprolactam and the like.
  • the acrylic base polymer may contain a monomer component other than the above.
  • the acrylic base polymer includes, as monomer components, for example, a cyano group-containing monomer, a vinyl ester monomer, an aromatic vinyl monomer, an epoxy group-containing monomer, a vinyl ether monomer, a sulfo group-containing monomer, a phosphate group-containing monomer, and an acid anhydride group-containing It may contain a monomer or the like.
  • the weight average molecular weight of the acrylic base polymer is preferably from 100,000 to 5,000,000, more preferably from 300,000 to 3,000,000, and still more preferably from 500,000 to 2,000,000.
  • the molecular weight of the base polymer refers to the molecular weight before the introduction of the crosslinked structure.
  • the adhesive tends to be harder as the content of the high Tg monomer component in the constituent components of the base polymer is larger.
  • the high Tg monomer means a monomer having a high glass transition temperature (Tg) of a homopolymer. Monomers having a homopolymer Tg of 40 ° C.
  • dicyclopentanyl methacrylate Tg: 175 ° C.
  • dicyclopentanyl acrylate Tg: 120 ° C.
  • isobornyl methacrylate Tg: 173 ° C.
  • (Meth) acrylic monomers such as nyl acrylate (Tg: 97 ° C.), methyl methacrylate (Tg: 105 ° C.), 1-adamantyl methacrylate (Tg: 250 ° C.), 1-adamantyl acrylate (Tg: 153 ° C.); acryloyl morpholine (Tg: 145 ° C), dimethylacrylamide (Tg: 119 ° C), diethylacrylamide (Tg: 81 ° C), dimethylaminopropylacrylamide (Tg: 134 ° C), isopropylacrylamide (Tg: 134 ° C), hydroxyethylacrylamide ( g: 98 ° C.) amide group
  • the content of the monomer having a homopolymer Tg of 40 ° C. or higher is preferably 1 to 50% by weight, more preferably 3 to 40% by weight, based on the total amount of the constituent monomer components. .
  • the homopolymer has a Tg of 80 ° C. or higher as a monomer component of the base polymer. More preferably, it contains a monomer component at 100 ° C. or higher.
  • the content of the monomer having a homopolymer Tg of 100 ° C. or more based on the total amount of the constituent monomer components is preferably 0.1% by weight or more, more preferably 0.5% by weight or more. , More preferably 1% by weight or more, particularly preferably 3% by weight or more.
  • an acrylic polymer as a base polymer can be obtained by polymerizing the above monomer components by various known methods such as solution polymerization, emulsion polymerization and bulk polymerization.
  • the solution polymerization method is preferred from the viewpoint of the balance of properties such as adhesive strength and holding power of the pressure-sensitive adhesive and cost.
  • Ethyl acetate, toluene and the like are used as a solvent for solution polymerization.
  • the solution concentration is usually about 20 to 80% by weight.
  • As the polymerization initiator used for the solution polymerization various known ones such as an azo type and a peroxide type can be used. In order to adjust the molecular weight, a chain transfer agent may be used.
  • the reaction temperature is usually about 50 to 80 ° C., and the reaction time is usually about 1 to 8 hours.
  • a crosslinked structure is introduced into the base polymer.
  • a cross-linking agent is added to a solution obtained by polymerizing the base polymer, and if necessary, heating is performed to introduce a cross-linked structure.
  • the crosslinking agent include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a carbodiimide-based crosslinking agent, and a metal chelate-based crosslinking agent.
  • crosslinking agents react with functional groups such as a hydroxy group and a carboxy group introduced into the base polymer to form a crosslinked structure.
  • Isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred because they have high reactivity with hydroxy groups and carboxy groups of the base polymer and can easily introduce a crosslinked structure.
  • the isocyanate-based crosslinking agent a polyisocyanate having two or more isocyanate groups in one molecule is used.
  • the isocyanate-based cross-linking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; Aromatic isocyanates such as isocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate; trimethylolpropane / tolylene diisocyanate trimer adduct (eg, “Coronate L” manufactured by Tosoh Corporation), trimethylolpropane / hexamethylene Diisocyanate trimer adduct (eg, “Coronate HL” manufactured by Toso
  • epoxy-based crosslinking agent a polyfunctional epoxy compound having two or more epoxy groups in one molecule is used.
  • the epoxy group of the epoxy-based crosslinking agent may be a glycidyl group.
  • examples of the epoxy crosslinking agent include N, N, N ′, N′-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, 6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, penta Erythritol polyglycidyl
  • the amount of the crosslinking agent used may be appropriately adjusted according to the composition and molecular weight of the base polymer.
  • the amount of the crosslinking agent to be used is about 0.01 to 10 parts by weight, preferably 0.1 to 7 parts by weight, more preferably 0.2 to 6 parts by weight, and still more preferably 100 parts by weight of the base polymer. 0.3 to 5 parts by weight.
  • the value obtained by dividing the amount (parts by weight) of the crosslinking agent used per 100 parts by weight of the base polymer by the functional group equivalent (g / eq) of the crosslinking agent is preferably 0.00015 to 0.11, more preferably 0.001 to 0.
  • 0.077 is more preferable, 0.003 to 0.055 is more preferable, and 0.0045 to 0.044 is particularly preferable.
  • Glue on the adherend during rework by increasing the amount of the cross-linking agent used to make the adhesive moderately harder than general acrylic optical transparent adhesives for permanent adhesion The remainder tends to decrease and the reworkability improves.
  • a cross-linking catalyst may be used to promote the formation of a cross-linked structure.
  • a crosslinking catalyst for an isocyanate-based crosslinking agent a metal-based crosslinking catalyst (particularly, a tin-based crosslinking catalyst) such as tetra-n-butyl titanate, tetraisopropyl titanate, ferric nasem, butyltin oxide, dioctyltin dilaurate, and dibutyltin dilaurate And the like.
  • the use amount of the crosslinking catalyst is generally 0.05 parts by weight or less based on 100 parts by weight of the base polymer.
  • the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer 2 contains a photocuring agent in addition to the base polymer.
  • a photocuring agent in addition to the base polymer.
  • the photocuring agent a photocurable monomer or a photocurable oligomer having two or more polymerizable functional groups in one molecule is used.
  • the photocuring agent is preferably a compound having an ethylenically unsaturated bond such as a vinyl group or a (meth) acryloyl group as a polymerizable functional group.
  • the photo-curing agent is preferably a compound showing compatibility with the base polymer. It is preferable that the photocuring agent is liquid at normal temperature because it exhibits appropriate compatibility with the base polymer. When the photocuring agent is appropriately compatible with the base polymer and is uniformly dispersed in the composition, the wetting rate can be adjusted to an appropriate range.
  • the compatibility between the base polymer and the photocuring agent is mainly affected by the structure of the compound.
  • the structure and compatibility of the compound can be evaluated by, for example, a Hansen solubility parameter. The smaller the difference between the solubility parameters of the base polymer and the photocuring agent, the higher the compatibility tends to be.
  • polyfunctional (meth) acrylate As the photocuring agent because of its high compatibility with the acrylic base polymer.
  • Polyfunctional (meth) acrylates include polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, bisphenol A ethylene oxide-modified di (meth) acrylate, bisphenol A propylene oxide Modified di (meth) acrylate, alkanediol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, ethoxylated isocyanuric acid tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol di ( (Meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropanetetra (meth) acrylate
  • the compatibility between the base polymer and the photocuring agent also depends on the molecular weight of the compound.
  • the molecular weight of the photocuring agent is preferably 1500 or less, and more preferably 1000 or less.
  • the type and content of the photocuring agent affect the adhesive strength after photocuring.
  • the functional group equivalent is smaller (that is, the number of functional groups per unit molecular weight is larger) and the content of the photocuring agent is larger, the adhesive strength after photocuring tends to be larger.
  • the functional group equivalent (g / eq) of the photocuring agent is preferably equal to or less than 500, and more preferably equal to or less than 450.
  • the functional group equivalent of the photocuring agent is preferably 100 or more, more preferably 130 or more, and even more preferably 150 or more.
  • the functional group equivalent of the photocuring agent when the functional group equivalent of the photocuring agent is small, the interaction between the base polymer and the photocuring agent is strong, and the adhesive strength of the adhesive before photocuring. (Initial adhesive strength) tends to increase. In the use of the present invention, an excessive increase in the initial adhesive strength may lead to a decrease in reworkability. From the viewpoint of maintaining the adhesive strength between the pressure-sensitive adhesive layer 2 and the adherend before light curing in an appropriate range, the functional group equivalent of the light curing agent is preferably within the above range.
  • the content of the photocuring agent in the pressure-sensitive adhesive composition is preferably from 10 to 50 parts by weight, more preferably from 13 to 40 parts by weight, and still more preferably from 15 to 40 parts by weight, based on 100 parts by weight of the base polymer.
  • the photocurable compound is included in the pressure-sensitive adhesive composition as an uncured monomer or oligomer, the photocurable pressure-sensitive adhesive layer 2 is obtained.
  • the liquid photo-curing agent is localized near the surface of the pressure-sensitive adhesive layer (adhesion interface with the adherend), and the weak boundary layer ( Weak Boundary Layer; WBL) is easily formed.
  • WBL Weak Boundary Layer
  • An adhesive having a high gel fraction with a highly crosslinked base polymer generally has a predominant elastic behavior and tends to have low wettability to an adherend.
  • the characteristics of the surface change while maintaining the bulk characteristics of the pressure-sensitive adhesive layer. That is, when the WBL is formed, the viscosity of the surface is increased while maintaining the “hardness” of the adhesive as a bulk property, so that the wetting speed at the time of bonding is improved, and There is a tendency that peeling from the adherend becomes easy.
  • the compatibility between the base polymer and the photo-curing agent is excessively low, the photo-curing agent easily bleeds out on the surface of the pressure-sensitive adhesive layer, and WBL with a strong liquid property is formed on the surface of the pressure-sensitive adhesive layer, resulting in a large wetting speed. To rise. Therefore, the workability of bonding is improved, but the bleed-out photocuring agent may cause poor appearance and contamination of the adherend in some cases. Further, when the photocuring agent bleeds out to form a liquid WBL, the initial adhesive strength may be insufficient due to the difficulty in holding the step. When the compatibility between the photocuring agent and the base polymer is low, the adhesive properties as a bulk hardly increase even when the pressure-sensitive adhesive is photocured, and the adhesion reliability of the reinforcing film may be poor.
  • the wetting rate is an index of the bonding workability and also an index of the compatibility between the base polymer and the photocuring agent.
  • the wetting rate is low, the bonding workability is low, and bonding defects such as mixing of air bubbles and entrapment of foreign matter are likely to occur.
  • the wetting rate is excessively high, bleed out of the photocuring agent and poor adhesion are likely to occur.
  • wetting rate is preferably 0.3 ⁇ 4 cm 2 / sec, more preferably 0.35 ⁇ 3.5 cm 2 / sec, more preferably 0.4 ⁇ 3 cm 2 / sec, 0.45 Particularly preferred is ⁇ 2.5 cm 2 / sec.
  • the wetting rate can be adjusted to the above range by adjusting the content of the photocuring agent, controlling the compatibility between the base polymer and the photocuring agent, and the like.
  • the wetting rate tends to increase as the content of the photocuring agent in the photocurable pressure-sensitive adhesive composition increases. Also, the lower the compatibility between the base polymer and the photocuring agent, the higher the wetting rate tends to be.
  • the compatibility between the base polymer and the photocuring agent can be adjusted by the similarity of their chemical structures (solubility parameter), the molecular weight of the photocuring agent, the functional group equivalent, and the like.
  • the photocuring agent has a similar chemical structure
  • the larger the functional group equivalent the larger the molecular weight of the molecular chain connecting the polymerizable functional groups
  • the wetting rate tends to increase as the number of repeating units of ethylene oxide (EO) increases.
  • the number of repeating units of EO is preferably about 2 to 8, more preferably about 3 to 7.
  • the photopolymerization initiator generates active species upon irradiation with actinic rays, and promotes the curing reaction of the photocuring agent.
  • a photocationic initiator photoacid generator
  • a photoradical initiator photoradical initiator
  • a photoanion initiator photobase generator
  • an ethylenically unsaturated compound such as a polyfunctional acrylate
  • the photo-radical initiator generates radicals upon irradiation with actinic rays, and promotes the radical polymerization reaction of the photo-curing agent by the radical transfer from the photo-radical initiator to the photo-curing agent.
  • the photo-radical initiator photo-radical generator
  • those that generate radicals by irradiation with visible light or ultraviolet light having a wavelength shorter than 450 nm are preferable, and include hydroxyketones, benzyldimethylketals, aminoketones, and acylphosphines. Examples include oxides, benzophenones, and triazine derivatives containing a trichloromethyl group.
  • the photo-radical initiator may be used alone or in combination of two or more.
  • the photopolymerization initiator When transparency is required for the pressure-sensitive adhesive layer 2, the photopolymerization initiator preferably has low sensitivity to light (visible light) having a wavelength longer than 400 nm.
  • the extinction coefficient at a wavelength of 405 nm is 1 ⁇ 10 2 [ [mLg ⁇ 1 cm ⁇ 1 ] or less is preferably used.
  • the content of the photopolymerization initiator in the pressure-sensitive adhesive layer 2 is preferably 0.01 to 5 parts by weight, more preferably 0.02 to 3 parts by weight, and more preferably 0.03 to 2 parts by weight based on 100 parts by weight of the base polymer. Parts are more preferred.
  • the content of the photopolymerization initiator in the pressure-sensitive adhesive layer 2 is preferably 0.02 to 10 parts by weight, more preferably 0.05 to 7 parts by weight, and more preferably 0.1 to 5 parts by weight based on 100 parts by weight of the photocuring agent. Part by weight is more preferred.
  • the adhesive layer contains a silane coupling agent, a tackifier, a plasticizer, a softener, a deterioration inhibitor, a filler, a colorant, an ultraviolet absorber, an antioxidant, and a surfactant.
  • An additive such as an agent or an antistatic agent may be contained within a range that does not impair the characteristics of the present invention.
  • the pressure-sensitive adhesive layer 2 may be formed directly on the film substrate 1, or a pressure-sensitive adhesive layer formed in a sheet shape on another substrate may be transferred onto the film substrate 1.
  • the above-mentioned pressure-sensitive adhesive composition is subjected to roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, die coating, etc.
  • the pressure-sensitive adhesive layer is formed by applying the composition on a base material and, if necessary, drying and removing the solvent.
  • a drying method an appropriate method can be adopted as appropriate.
  • the heating and drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and even more preferably 70 ° C to 170 ° C.
  • the drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 15 minutes, and even more preferably 10 seconds to 10 minutes.
  • the pressure-sensitive adhesive composition contains a crosslinking agent
  • the heating temperature and the heating time are appropriately set depending on the type of the crosslinking agent to be used, and the crosslinking is usually carried out in the range of 20 ° C. to 160 ° C. by heating for about 1 minute to 7 days. Heating for drying and removing the solvent may also serve as heating for crosslinking.
  • the gel fraction is increased by introducing a crosslinked structure into the base polymer.
  • the higher the gel fraction the harder the pressure-sensitive adhesive, and there is a tendency that adhesive residue on the adherend is suppressed when the reinforcing film is peeled off from the adherend by rework or the like.
  • the gel fraction of the pressure-sensitive adhesive layer 2 before photocuring is preferably 30% or more, more preferably 50% or more, still more preferably 60% or more, and particularly preferably 65% or more.
  • the gel fraction of the pressure-sensitive adhesive layer 2 before the photocuring may be 70% or more or 75% or more.
  • the gel fraction of the pressure-sensitive adhesive layer 2 before the photocuring is preferably 95% or less, more preferably 90% or less, further preferably 85% or less, and particularly preferably 80% or less.
  • the gel fraction can be determined as an insoluble component in a solvent such as ethyl acetate. Specifically, the gel component is immersed in ethyl acetate at 23 ° C. for 7 days, and the insoluble component is determined based on the sample before immersion. It is determined as a weight fraction (unit: weight%). Generally, the gel fraction of a polymer is equal to the degree of crosslinking, and the more crosslinked portions in the polymer, the greater the gel fraction.
  • the photocurable pressure-sensitive adhesive layer 2 including the base polymer and the photocurable agent is formed.
  • the pressure-sensitive adhesive layer 2 is formed on the film substrate 1, it is preferable to provide a separator 5 on the pressure-sensitive adhesive layer 2 for the purpose of protecting the pressure-sensitive adhesive layer 2 and the like. Crosslinking may be performed after the separator 5 is provided on the pressure-sensitive adhesive layer 2.
  • the solvent is dried, and then the pressure-sensitive adhesive layer 2 is transferred onto the film substrate 1 to obtain a reinforcing film.
  • the substrate used for forming the pressure-sensitive adhesive layer may be used as the separator 5 as it is.
  • a plastic film such as polyethylene, polypropylene, polyethylene terephthalate, or polyester film is preferably used.
  • the thickness of the separator is usually about 3 to 200 ⁇ m, preferably about 10 to 100 ⁇ m.
  • the contact surface of the separator 5 with the pressure-sensitive adhesive layer 2 may be subjected to a release treatment with a silicone-based, fluorine-based, long-chain alkyl-based, or fatty acid amide-based release agent, or a silica powder or the like. preferable.
  • the reinforcing film is used by being bonded to an adherend such as a device or a device component.
  • an adherend such as a device or a device component.
  • the reinforcing film of the present invention has a higher wetting rate than a general adhesive sheet for permanent adhesion, it is possible to suppress the entrapment of air bubbles and foreign substances when bonding the reinforcing film to the adherend, Excellent workability.
  • the reinforcing film has an appropriate wetting speed and an initial adhesive force, peeling from the adherend during storage and handling can be suppressed.
  • the reinforcing film when a reinforcing film is bonded to a work-in-progress, the reinforcing film may be bonded to a large-size work-in-process before being cut into a product size.
  • a reinforcing film may be bonded to a mother roll of a device manufactured by a roll-to-roll process by a roll-to-roll process.
  • the adherend to which the reinforcing film is attached is not particularly limited, and includes various electronic devices, optical devices, and components thereof. As devices become more highly integrated, smaller, lighter, and thinner, the thickness of members constituting the device tends to decrease. As the thickness of the constituent members is reduced, bending and curling due to stress and the like at the lamination interface are likely to occur. In addition, bending due to its own weight is likely to occur due to the reduction in thickness.
  • By attaching the reinforcing film rigidity can be imparted to the adherend, so that bending, curling, bending, and the like due to stress, own weight, and the like are suppressed, and handling properties are improved. Therefore, by attaching the reinforcing film to the work-in-progress in the device manufacturing process, it is possible to prevent defects and defects during transportation and processing by an automated device.
  • the reinforcing film 10 Since the reinforcing film 10 has a stress dispersibility due to the pressure-sensitive adhesive layer 2, the reinforcing film 10 is attached to the object to be conveyed and the object to be processed, so that appropriate rigidity is imparted and stress is reduced. Dispersion can prevent defects such as cracks, cracks, peeling, and dimensional changes.
  • the reinforcing film 10 may be bonded to the entire surface of the adherend 20 or may be selectively bonded only to a portion requiring reinforcement. After the reinforcing film is attached to the entire surface of the adherend, the reinforcing film may be cut off at a portion that does not require reinforcement, and may be separated from the surface of the adherend. Before the treatment for increasing the adhesive strength of the pressure-sensitive adhesive layer 2, the reinforcing film is temporarily attached to the surface of the adherend, so that the reinforcing film 10 can be easily peeled off from the surface of the adherend 20.
  • the adhesive strength of the pressure-sensitive adhesive layer 2 to the glass plate before light curing is preferably 0.03 N / 25 mm or more and less than 1 N / 25 mm, more preferably 0.05 to 0.8 N / 25 mm, and 0.1 to 0.7 N. / 25 mm is more preferable, and 0.2 to 0.6 N / 25 mm is particularly preferable.
  • the adhesive strength of the reinforcing film to the polyimide film be in the above range before the pressure-sensitive adhesive layer 2 is cured by light.
  • a flexible display panel a flexible printed wiring board (FPC), a device in which a display panel and a wiring board are integrated, a flexible substrate material is used, and from the viewpoint of heat resistance and dimensional stability, generally, And a polyimide film.
  • the reinforcing film in which the pressure-sensitive adhesive layer 2 has the above-mentioned adhesive strength to the polyimide film as a substrate is easy to peel off from the polyimide adherend before the light-curing of the pressure-sensitive adhesive layer 2 and adheres after the light-curing. Excellent reliability.
  • the pressure-sensitive adhesive layer 2 preferably has a shear storage modulus G ′ i at 25 ° C. before light curing of 1 ⁇ 10 4 to 1.2 ⁇ 10 5 Pa.
  • the shear storage elastic modulus (hereinafter simply referred to as “storage elastic modulus”) is determined under the conditions of a frequency of 1 Hz according to the method described in JIS K7244-1 “Plastics—Testing method for dynamic mechanical properties”. It can be obtained by reading a value at a predetermined temperature when measured at a heating rate of 5 ° C./min in the range of 50 to 150 ° C.
  • the storage elastic modulus G ′ is used as an index indicating the degree of hardness.
  • the storage elastic modulus of the pressure-sensitive adhesive layer has a high correlation with the cohesive force, and the higher the cohesive force of the pressure-sensitive adhesive, the greater the anchoring force to the adherend. If the storage elastic modulus of the pressure-sensitive adhesive layer 2 before light curing is 1 ⁇ 10 4 Pa or more, the pressure-sensitive adhesive has sufficient hardness and cohesive force, has an appropriate wetting speed, and is reinforced from the adherend. When the film is peeled, adhesive residue on the adherend is hardly generated.
  • the storage elastic modulus of the pressure-sensitive adhesive layer 2 When the storage elastic modulus of the pressure-sensitive adhesive layer 2 is large, it is possible to suppress the pressure-sensitive adhesive from protruding from the end face of the reinforcing film. If the storage elastic modulus of the pressure-sensitive adhesive layer 2 before light curing is 1.2 ⁇ 10 5 Pa or less, peeling at the interface between the pressure-sensitive adhesive layer 2 and the adherend is easy, and even when rework is performed. In addition, cohesive failure of the pressure-sensitive adhesive layer and adhesive residue on the surface of the adherend hardly occur. From the viewpoint of enhancing the reworkability of the reinforcing sheet and suppressing adhesive residue on the adherend during rework, the storage elastic modulus G ′ i of the pressure-sensitive adhesive layer 2 at 25 ° C. before light curing is 3 ⁇ 10 4 to 1 ⁇ 10 5 Pa is more preferred, and 4 ⁇ 10 4 to 9.5 ⁇ 10 4 Pa is even more preferred.
  • the pressure-sensitive adhesive layer 2 is light-cured.
  • Actinic rays include ultraviolet light, visible light, infrared light, X-rays, ⁇ -rays, ⁇ -rays, and ⁇ -rays. Ultraviolet rays are preferable as the actinic rays, since curing of the pressure-sensitive adhesive layer in the storage state can be suppressed and curing is easy.
  • the irradiation intensity and irradiation time of the actinic ray may be appropriately set according to the composition and thickness of the pressure-sensitive adhesive layer. Irradiation of the actinic ray to the pressure-sensitive adhesive layer 2 may be performed from any of the film substrate 1 side and the adherend 20 side, or may be performed from both sides.
  • the adhesive force of the pressure-sensitive adhesive layer 2 to the glass plate before light curing is preferably 1 N / 25 mm or more, more preferably 2 N / 25 mm or more, and more preferably 3 N / 25 mm or more. 25 mm or more is more preferable.
  • the reinforcing film preferably has an adhesive strength to the polyimide film in the above range after the pressure-sensitive adhesive layer 2 is cured.
  • the adhesive strength between the pressure-sensitive adhesive layer 2 and the adherend after light curing is preferably twice or more, more preferably three times or more, and more preferably five times the adhesive strength between the pressure-sensitive adhesive layer 2 and the adherend before light curing. The above is more preferred.
  • the pressure-sensitive adhesive layer 2 preferably has a storage elastic modulus G ′ f at 25 ° C. after photocuring of 1.5 ⁇ 10 5 Pa or more.
  • the storage elastic modulus of the pressure-sensitive adhesive layer 2 after photocuring is 1.5 ⁇ 10 5 Pa or more, the adhesive force with the adherend is improved with an increase in cohesive force, and high adhesive reliability is obtained.
  • the storage elastic modulus is excessively large, the pressure-sensitive adhesive does not easily spread and spread, and the contact area with the adherend decreases. Further, since the stress dispersibility of the pressure-sensitive adhesive decreases, the peeling force tends to propagate to the bonding interface, and the bonding force with the adherend tends to decrease.
  • the storage modulus G 'f at 25 ° C. after light curing of the adhesive layer 2 is preferably 2 ⁇ 10 6 Pa or less.
  • G ' f is more preferably 1.8 ⁇ 10 5 to 1.2 ⁇ 10 6 Pa, and 2 ⁇ 10 5 to 1 ⁇ 10 6 Pa. 6 Pa is more preferred.
  • the ratio G ′ f / G ′ i of the storage modulus at 25 ° C. before and after photocuring of the pressure-sensitive adhesive layer 2 is preferably 2 or more. If G ′ f is at least twice as large as G ′ i , the increase in G ′ due to photocuring is large, and it is possible to achieve both reworkability before photocuring and adhesion reliability after photocuring.
  • G ′ f / G ′ i is more preferably 4 or more, still more preferably 8 or more, particularly preferably 10 or more.
  • G 'f / G' i is not particularly limited, G if 'f / G' i is excessively large, the pre photocurable G 'initial adhesion failure due to small, or G after photocuring' Is excessively large, which tends to lead to a decrease in bonding reliability. Therefore, G ' f / G' i is preferably 100 or less, more preferably 40 or less, still more preferably 30 or less, and particularly preferably 25 or less.
  • the adherend 20 to which the reinforcing film 10 has been attached may be subjected to an autoclave treatment for the purpose of improving the affinity of the lamination interface of the plurality of laminated members or the like, or a heat treatment such as thermocompression bonding for joining circuit members. is there.
  • a heat treatment such as thermocompression bonding for joining circuit members. it is preferable that the pressure-sensitive adhesive between the reinforcing film and the adherend does not flow from the end face.
  • the storage elastic modulus at 100 ° C. of the pressure-sensitive adhesive layer 2 after photocuring is preferably 5 ⁇ 10 4 Pa or more, more preferably 8 ⁇ 10 4 Pa or more, The pressure is more preferably 1 ⁇ 10 5 Pa or more.
  • the storage elastic modulus at 100 ° C. of the adhesive layer 2 after photocuring is 60% of the storage elastic modulus at 50 ° C. Or more, more preferably 65% or more, still more preferably 70% or more, and particularly preferably 75% or more.
  • the pressure-sensitive adhesive layer 2 is photocurable, and the curing timing can be arbitrarily set. Processing such as rework and processing of the reinforcing film can be performed at any timing after the reinforcing film is attached to the adherend and before the adhesive is photo-cured. It is possible to respond flexibly.
  • the photo-curing of the pressure-sensitive adhesive layer 2 causes the reinforcing film 10 to be firmly adhered to the adherend 20. Even if external force is suddenly applied by dropping the device, placing a heavy object on the device, or hitting a flying object on the device, the reinforcing film is attached to prevent damage to the device it can. Further, since the pressure-sensitive adhesive layer is firmly adhered, the reinforcing film is hardly peeled off even during long-term use, and is excellent in reliability.
  • ⁇ Polymer B> The charged amounts of the monomers were changed to 95 parts by weight of butyl acrylate (BA) and 5 parts by weight of acrylic acid (AA). Otherwise, polymerization was carried out in the same manner as in Polymer A to obtain a solution of acrylic polymer B.
  • BA butyl acrylate
  • AA acrylic acid
  • ⁇ Polymer C> As the polyol, 85 parts by weight of a polyether polyol having three hydroxyl groups and having a number average molecular weight of 10,000 (“S3011” manufactured by Asahi Glass) and 13 parts by weight of a polyether polyol having three hydroxyl groups (“SANNIX GP3000” manufactured by Sanyo Chemical) And 2 parts by weight of a polyether polyol having three hydroxyl groups and having a number average molecular weight of 1000 (“SANIX GP1000” manufactured by Sanyo Chemical Industries, Ltd.).
  • isocyanurate of hexamethylene diisocyanate (“Coronate HX” manufactured by Tosoh Corporation) 18 parts by weight, 0.04 parts by weight of iron (III) acetylacetonate as a catalyst, and 210 parts by weight of ethyl acetate as a diluting solvent were mixed and stirred at room temperature to obtain a urethane polymer C solution.
  • Example 1 (Preparation of adhesive composition) 3.3 parts by weight of a solution of acrylic polymer A (300 parts by weight of solid content) in a 75% ethyl acetate solution of trimethylolpropane adduct of xylylene diisocyanate as an isocyanate-based cross-linking agent (“Takenate D110N” manufactured by Mitsui Chemicals) 3.3 Parts by weight (solid content: 2.5 parts by weight), 0.005 parts by weight of iron (III) acetylacetonate as a crosslinking catalyst, and 20 parts by weight of "Aronix M-321" manufactured by Toagosei Co., Ltd. as a photocuring agent (polyfunctional acrylic monomer).
  • the above-mentioned pressure-sensitive adhesive composition was applied using a fountain roll onto a 75 ⁇ m-thick polyethylene terephthalate film (“Lumirror S10” manufactured by Toray Co., Ltd.) that had not been subjected to surface treatment so that the thickness after drying was 25 ⁇ m. After drying at 130 ° C. for 1 minute to remove the solvent, a release-treated surface of a separator (a 25 ⁇ m-thick polyethylene terephthalate film whose surface was subjected to silicone release treatment) was adhered to the pressure-sensitive adhesive applied surface.
  • a 75 ⁇ m-thick polyethylene terephthalate film (“Lumirror S10” manufactured by Toray Co., Ltd.) that had not been subjected to surface treatment so that the thickness after drying was 25 ⁇ m.
  • a release-treated surface of a separator a 25 ⁇ m-thick polyethylene terephthalate film whose surface was subjected to silicone release treatment
  • Examples 2 to 7 and Comparative Examples 1 to 4 In the preparation of the pressure-sensitive adhesive composition, a reinforcing film was produced in the same manner as in Example 1, except that the type of the photocuring agent was changed as shown in Table 1. In Comparative Example 4, the amount of the isocyanate-based crosslinking agent was changed, and the photo-curing agent was not added.
  • Example 8 0.5 parts by weight of a tetrafunctional epoxy crosslinking agent (“Tetrad C” manufactured by Mitsubishi Gas Chemical) in 300 parts by weight of a solution of the acrylic polymer B (100 parts by weight of solid content), and Shin-Nakamura Chemical Industry as a polyfunctional acrylic monomer 20 parts by weight of “NK Ester A-200” manufactured by BASF and 0.1 part by weight of “IRGACURE 184” manufactured by BASF were added as a photopolymerization initiator to prepare a photocurable acrylic pressure-sensitive adhesive solution. Using this adhesive solution, a reinforcing film was obtained in the same manner as in Example 1.
  • a tetrafunctional epoxy crosslinking agent (“Tetrad C” manufactured by Mitsubishi Gas Chemical) in 300 parts by weight of a solution of the acrylic polymer B (100 parts by weight of solid content)
  • Shin-Nakamura Chemical Industry as a polyfunctional acrylic monomer 20 parts by weight of “NK Ester A-200” manufactured by BASF and 0.1 part by weight of “IR
  • ⁇ Wetting speed> A state in which a pressure-sensitive adhesive layer at one end in the length direction of a test piece obtained by peeling and removing a separator from the surface of a reinforcing film cut into a width of 25 mm and a length of 150 mm is in contact with a glass plate ("Micro slide glass S" manufactured by Matsunami Glass Industry Co., Ltd.) The other end of the test piece was held by a hand so that the angle between the glass plate and the test piece was 20 to 30 °, and the hand was released from the test piece, and the adhesive layer of the test piece came into contact with the glass plate.
  • a glass plate (“Micro slide glass S" manufactured by Matsunami Glass Industry Co., Ltd.)
  • a test piece obtained by peeling and removing the separator from the surface of the reinforcing film cut into a width of 25 mm and a length of 100 mm was bonded to a glass plate using a hand roller to obtain a test sample before light curing.
  • the test sample obtained by irradiating ultraviolet light from the PET film side of the test sample and photocuring the pressure-sensitive adhesive layer was used as the test sample after photocuring.
  • the test piece was held by a chuck, and a 180 ° peel of the reinforcing film was performed at a tensile speed of 300 mm / min, and the peel strength was measured.
  • Table 1 shows the composition of the pressure-sensitive adhesive of each reinforcing sheet and the evaluation results.
  • the amounts of the crosslinking agent and the photocuring agent in Table 1 are the amounts (parts by weight) based on 100 parts by weight of the base polymer. Details of the photocuring agent in Table 1 are as follows.
  • the reinforcing films of Comparative Examples 1 to 3 exhibited high wettability to the glass plate and high wettability to the adherend, but the surface of the pressure-sensitive adhesive layer was clouded, and bleed out of the photocuring agent was observed. .
  • the adhesive strength before light curing was insufficient, and the adhesive strength after light curing was also insufficient.
  • the reinforcing film of Comparative Example 5 using a urethane-based pressure-sensitive adhesive showed a higher wetting rate than Comparative Examples 1 to 3, but had insufficient adhesion to a glass plate as in Comparative Examples 1 to 3. It could not be used as a reinforcing film for permanent adhesion to an adherend.
  • the reinforcing film of Comparative Example 4 using an adhesive containing no photocuring agent showed high adhesive strength when pressed against a glass plate using a hand roller, but was only placed on the glass plate without applying pressure. In this case, the pressure-sensitive adhesive did not spread on the surface of the glass plate, and the wetting speed could not be measured.
  • the reinforcing films of Examples 1 to 8 exhibited an appropriate wetting rate with respect to the glass plate, had an adhesive strength before light curing within an appropriate range, and had both adhesiveness and reworkability. Further, after the photocuring, it exhibited a high adhesive strength and was suitable as a reinforcing film having excellent adhesion reliability to the device.
  • Example 4 Comparative Example 2 and Comparative Example 3, polyethylene glycol diacrylate was used as the photocuring agent. In Example 4, however, good characteristics were exhibited, whereas Comparative Example 2 and Comparative Example In No. 3, the wetting rate was excessively high, and the adhesion to the glass plate was insufficient. In Comparative Examples 2 and 3, the photocuring agent bleeds out to the surface due to the decrease in compatibility between the acrylic base polymer and the photocuring agent with the increase in the number of repeating units of ethylene oxide. It is considered that the property has decreased.

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Abstract

La présente invention concerne un film de renforcement (10) comprenant une couche d'agent adhésif (2) qui est fixée/stratifiée sur une surface principale d'un substrat de support (1) du film. La couche d'agent adhésif est formée à partir d'une composition photodurcissable comprenant un polymère de base, un agent photodurcissable et un initiateur de photopolymérisation. Le film de renforcement a une vitesse d'humidification, par rapport à une feuille de verre, de 0,3 à 4 cm2/seconde. Ce film de renforcement peut être facilement retravaillé immédiatement après avoir été fixé à un support, une solide adhérence avec le support est possible, et la durée jusqu'à ce que l'adhésivité s'accroît après fixation à un support peut être librement définie.
PCT/JP2019/031726 2018-08-27 2019-08-09 Film de renforcement Ceased WO2020045067A1 (fr)

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