CN111548753B - Reinforcing film, method for manufacturing device, and method for enhancing - Google Patents

Abstract

Enhanced films, methods of making devices, and methods of enhancement are provided. The reinforcement film (10) includes a film base material and an adhesive layer (2) fixedly laminated on one main surface of the film base material. The adhesive layer contains a photocurable composition. The photocurable composition constituting the adhesive layer contains a base polymer, a photocuring agent, and a photopolymerization initiator. The base polymer is substantially free of nitrogen atoms. A crosslinked structure may be introduced into the base polymer.

Description

Reinforcing film, method for manufacturing device, and method for enhancing

technical field

The present invention relates to a reinforcing film in which a film substrate and a photocurable pressure-sensitive adhesive layer are fixed and laminated. Furthermore, the present invention relates to a method of manufacturing a device having a reinforcement film attached to the surface thereof, and a reinforcement method of laminating the reinforcement film to the surface of an adherend.

Background technique

On the surfaces of optical devices such as displays and electronic devices, there are cases where an adhesive film is attached for the purpose of surface protection, imparting impact resistance, and the like. Such an adhesive film usually has a pressure-sensitive adhesive layer laminated on the main surface of the film base material, and is attached to the device surface via the pressure-sensitive adhesive layer.

Damage and breakage of the adherend can be suppressed by temporarily fixing the adhesive film to the surface of the device or the device constituent member in a state before use such as assembly, processing, and transportation of the device. The adhesive film temporarily fixed for the purpose of temporarily protecting the surface in this way can be easily peeled off from the adherend without generating adhesive residue to the adherend.

Patent Document 1 discloses an adhesive film that is used in a state of being attached to the surface of the device when the device is used, in addition to assembly, processing, transportation, and the like of the device. In addition to surface protection, such an adhesive film has a function of reinforcing the device by dispersing impact to the device, imparting rigidity to the flexible device, and the like.

When the adhesive film is attached to an adherend, there may be cases in which poor adhesion occurs, such as mixing of air bubbles and shifting of the adhesion position. When a sticking failure occurs, an operation (reprocessing) of peeling the adhesive film from the adherend and sticking another adhesive film is performed. Since the adhesive film used as an engineering material is designed on the premise of peeling from the adherend, reprocessing is easy. On the other hand, a reinforcement film premised on permanent adhesion is generally not intended to be peeled off from the device, but is firmly adhered to the surface of the device, and thus it is difficult to rework.

Patent Document 2 discloses an adhesive film including a pressure-sensitive adhesive layer designed to have low adhesiveness immediately after being attached to an adherend and to increase the adhesive force with time. The timing of the increase in the adhesive force caused by curing after sticking to the adherend can be arbitrarily set for the adhesive that is triggered by light and/or heat to increase the adhesive force. Moreover, since the adhesive force is small immediately after sticking (before the adhesive force increasing process), it is easy to peel from the to-be-adhered body, and it can utilize as a reinforcement film which has reworkability.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2017-132977

Patent Document 2: International Publication No. 2015/163115

SUMMARY OF THE INVENTION

Invention to solve problem

Before sticking a reinforcing film to the surface of an adherend such as a device, surface activation treatment such as plasma treatment and corona treatment is sometimes performed for the purpose of cleaning the surface of the adherend. When the reinforcement film is attached to the surface of the adherend after the surface activation treatment, compared with the case where the reinforcement film is attached to the adherend that has not been subjected to the surface activation treatment, the adhesive force is greatly increased, and the reinforcement film is peeled from the adherend. (Reprocessing) sometimes becomes difficult.

In view of the above problems, an object of the present invention is to provide a reinforcement film having low initial adhesion to an adherend and excellent reworkability even when the adherend surface is activated by plasma or the like.

solution to the problem

The inventors of the present invention conducted studies in view of the above-mentioned problems, and as a result, found that when the base polymer constituting the pressure-sensitive adhesive layer has a predetermined composition, the initial adhesive force due to the presence or absence of the surface activation treatment of the adherend The difference is small, and it also has excellent reworkability for the adherend that has undergone surface activation treatment.

The reinforcing film of the present invention includes an adhesive layer fixedly laminated on one main surface of the film substrate. The adhesive layer contains a photocurable composition containing a base polymer, a photocuring agent, and a photopolymerization initiator.

As the base polymer of the adhesive layer, for example, an acrylic polymer is used. By making the base polymer substantially free of nitrogen atoms, it is possible to suppress an increase in the initial adhesion force to the adherend even when the adherend surface is activated by plasma treatment or the like.

Preferably, a crosslinked structure is introduced into the base polymer. For example, a base polymer contains a hydroxyl group-containing monomer and/or a carboxyl group-containing monomer as a monomer unit, and a crosslinking agent such as a polyfunctional isocyanate compound and a polyfunctional epoxy compound is bonded to these functional groups, thereby introducing a crosslinked structure. The crosslinking agent may or may not contain nitrogen atoms. If the base polymer before the introduction of the crosslinked structure does not substantially contain nitrogen atoms, even if the crosslinking agent contains nitrogen atoms, the increase in initial adhesive force can be suppressed.

The gel fraction of the pressure-sensitive adhesive layer (photocurable composition) may be 60% or more. When introducing a cross-linked structure, a cross-linking accelerator can be used. As the crosslinking accelerator, for example, an organometallic compound is used.

The photocuring agent of the adhesive layer is, for example, a polyfunctional (meth)acrylate. The functional group equivalent of the photocuring agent is preferably about 100 to 500 g/eq.

After the reinforcement film is temporarily fixed on the surface of the adherend, the adhesive layer is irradiated with actinic rays to photo-cure the adhesive layer, so that the adhesive force between the reinforcement film and the adherend is increased, and the surface of the adherend is obtained. A device in which a reinforcing film is fixed and laminated. When the adherend is a polyimide film, before photocuring the pressure-sensitive adhesive layer (temporarily fixed state), the adhesive force between the pressure-sensitive adhesive layer and the polyimide film is preferably 1 N/25 mm or less. Before temporarily fixing the reinforcing film on the adherend, the adherend may be subjected to surface activation treatment such as plasma treatment.

effect of invention

The adhesive layer of the reinforcement film of this invention contains a photocurable composition, and the adhesive force with an adherend improves by photocuring the adhesive layer after adhering to an adherend. Before photocuring the pressure-sensitive adhesive layer, since the adhesive force is small for the adherend subjected to activation treatment by plasma treatment or the like, reprocessing is easy, and high adhesive force is exhibited after photocuring.

Description of drawings

FIG. 1 is a cross-sectional view showing a laminated structure of reinforcing films.

FIG. 2 is a cross-sectional view showing a laminated structure of reinforcing films.

FIG. 3 is a cross-sectional view showing an apparatus for sticking a reinforcement film provided thereon.

Description of reference numerals

1 Film substrate

2 adhesive layers

10 Reinforcing film

5 Separator

20 Stickies

Detailed ways

FIG. 1 is a cross-sectional view showing an embodiment of a reinforcing film. The reinforcement film 10 includes the adhesive layer 2 on one main surface of the film base 1 . The adhesive layer 2 is fixedly laminated on one main surface of the base film 1 . The pressure-sensitive adhesive layer 2 is a photo-curable pressure-sensitive adhesive containing a photo-curable composition, and is cured by irradiation with actinic rays such as ultraviolet rays, thereby improving the adhesive force with the adherend.

FIG. 2 is a cross-sectional view of a reinforcing film to which a separator 5 is temporarily fixed on the main surface of the 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 release film 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 attached to the surface of the device 20 , so that the reinforcement film 10 is attached to the surface of the device 20 . This state is a state in which the reinforcing film 10 (adhesive layer 2 ) is temporarily fixed to the device 20 before the adhesive layer 2 is photocured. By photocuring the adhesive layer 2 , the adhesive force at the interface between the device 20 and the adhesive layer 2 increases, and the device 20 and the reinforcing film 10 are fixed.

The term "fixed" refers to a state in which the two laminated layers are firmly adhered, and the interface between them cannot be peeled off or is difficult to peel off. The "temporary fixation" refers to a state in which the adhesive force between the two laminated layers is small and can be easily peeled off at the interface between the two.

In the reinforcing film shown in FIG. 2 , the film base 1 and the adhesive layer 2 are fixed, and the separator 5 is temporarily fixed to the adhesive layer 2 . When the film substrate 1 and the separator 5 are peeled off, peeling occurs at the interface between the adhesive layer 2 and the separator 5 , and the state where the adhesive layer 2 is fixed to the film substrate 1 is maintained. No adhesive remains on the peeled separator 5 .

In the device shown in FIG. 3 to which the reinforcing film 10 is attached, before the photocuring of the adhesive layer 2 , the device 20 and the adhesive layer 2 are temporarily fixed. When the film substrate 1 and the device 20 are peeled off, peeling occurs at the interface between the adhesive layer 2 and the device 20 , and the state where the adhesive layer 2 is fixed to the film substrate 1 is maintained. Since no adhesive remains on the device 20, reprocessing is easy. After the pressure-sensitive adhesive layer 2 is photocured, the adhesive force between the pressure-sensitive adhesive layer 2 and the device 20 increases, so that it is difficult to peel off the film 1 from the device 20, and when both are peeled off, the pressure-sensitive adhesive layer 2 may be generated. A case of cohesion failure.

[Constitution of reinforcement film]

<Film base material>

A plastic film was used as the film substrate 1 . In order to fix the film base material 1 and the pressure-sensitive adhesive layer 2, it is preferable that the surface of the film base material 1 to which the pressure-sensitive adhesive layer 2 is attached is not subjected to mold release treatment.

The thickness of the film base material is, for example, about 4 to 500 μm. The thickness of the film substrate 1 is preferably 12 μm or more, more preferably 30 μm or more, and even more preferably 45 μm or more, from the viewpoint of reinforcing the device by imparting rigidity or alleviating impact. The thickness of the film substrate 1 is preferably 300 μm or less, and more preferably 200 μm or less, from the viewpoint of imparting flexibility to the reinforcing film and improving handleability. From the viewpoint of achieving both mechanical strength and flexibility, the compressive strength of the film substrate 1 is preferably 100 to 3000 kg/cm ² , more preferably 200 to 2900 kg/cm ² , still more preferably 300 to 2800 kg/cm ² , and particularly preferably 400～2700kg/cm ² .

As a plastic material which comprises the film base material 1, a polyester-type resin, a polyolefin-type resin, a cyclic polyolefin-type resin, a polyamide-type resin, a polyimide-type resin, etc. are mentioned. In the reinforcement film for optical devices, such as a display, it is preferable that the film base material 1 is a transparent film. In addition, in the case of photocuring the adhesive layer 2 by irradiating actinic rays from the side of the film substrate 1 , the film substrate 1 preferably has transparency with respect to the actinic ray used for curing the adhesive layer. From the viewpoint of achieving both mechanical strength and transparency, polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate can be suitably used. When the adhesive layer is cured by irradiating the actinic ray from the adherend side, the adherend only needs to have transparency to the actinic ray, and the film substrate 1 may be opaque to the actinic ray.

Functional coatings such as an easy-adhesion layer, an easy-slip layer, a mold release layer, an antistatic layer, a hard coat layer, and an antireflection layer can be provided on the surface of the film substrate 1 . In addition, as mentioned above, in order to fix the film base material 1 and the pressure-sensitive adhesive layer 2, it is preferable not to provide a mold release layer on the surface to which the pressure-sensitive adhesive layer 2 of the film base material 1 is attached.

<Adhesive layer>

The pressure-sensitive adhesive layer 2 fixedly laminated on the film substrate 11 contains a photocurable composition containing a base polymer, a photocuring agent, and a photopolymerization initiator. Since the adhesive force of the adhesive layer 2 to an adherend such as a device or a device member is small before photocuring, reprocessing is easy. Since the adhesive force of the pressure-sensitive adhesive layer 2 and the adherend is improved by photocuring, the reinforcing film is not easily peeled from the device surface even when the device is used, and the adhesion reliability is excellent.

When the reinforcing film is used in an optical device such as a display, the total light transmittance of the adhesive layer 2 is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The haze of the pressure-sensitive adhesive layer 2 is preferably 2% or less, more preferably 1% or less, still more preferably 0.7% or less, and particularly preferably 0.5% or less.

(base polymer)

The base polymer is the main constituent of the adhesive composition. From the viewpoint of setting the adhesiveness of the pressure-sensitive adhesive layer 2 before curing into an appropriate range, it is preferable to introduce a crosslinked structure into the base polymer. As the base polymer, a polymer substantially free of nitrogen atoms is used. The ratio of nitrogen in the constituent elements of the base polymer is preferably 0.1 mol % or less, more preferably 0.05 mol % or less, and further preferably 0.01 mol % or less. The ratio of nitrogen in the constituent elements of the base polymer may be 0.005 mol % or less, 0.001 mol % or less, or 0. In addition, when a crosslinked structure is introduce|transduced into a base polymer, the polymer before the introduction of a crosslinked structure should just not contain a nitrogen atom substantially, and a crosslinking agent may contain a nitrogen atom.

The type of the base polymer is not particularly limited as long as it does not substantially contain nitrogen atoms, and an acrylic polymer, a silicone-based polymer, a rubber-based polymer, or the like may be appropriately selected. In particular, the adhesive composition preferably contains an acrylic polymer as a base polymer from the viewpoint of being excellent in optical transparency and adhesiveness and easy to control adhesiveness, and preferably 50% by weight or more of the adhesive composition is Acrylic polymer.

As an acrylic polymer, what contains (meth)acrylic-acid alkylester as a main monomer component can be used suitably. In addition, in this specification, "(meth)acrylic acid" means acrylic acid and/or methacrylic acid.

As the alkyl (meth)acrylate, an alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group can be suitably used. The alkyl group of the alkyl (meth)acrylate may be linear or branched. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, (meth)acrylate Sec-butyl meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate , Heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, (meth)acrylate Isononyl acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, isodecyl (meth)acrylate Tridecyl ester, tetradecyl (meth)acrylate, isotetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, Heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, (meth)acrylic acid Aralkyl esters, etc.

The content of the alkyl (meth)acrylate is preferably 40% by weight or more, more preferably 50% by weight or more, and even more preferably 55% by weight or more with respect to the total amount of monomer components constituting the base polymer.

The acrylic base polymer preferably contains a monomer component having a crosslinkable functional group as a copolymerization component. 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 the adhesive residue to the adherend at the time of reprocessing tends to be reduced.

As a monomer which has a crosslinkable functional group, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are mentioned. The hydroxyl and carboxyl groups of the base polymer serve as reaction points with the crosslinking agent described later. For example, when an isocyanate-based crosslinking agent is used, it is preferable to contain a hydroxyl group-containing monomer as a copolymerization component of the base polymer. When an epoxy-type crosslinking agent is used, it is preferable to contain a carboxyl group-containing monomer as a copolymerization component of a base polymer. In addition, the base polymer preferably contains a carboxyl group-containing monomer as a monomer component from the viewpoint of improving the cohesion of the adhesive and containing substantially no nitrogen atoms.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxybutyl (meth)acrylate. Hydroxyhexyl, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, 4-(hydroxymethyl)ring (meth)acrylate Hexyl methyl ester, etc. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, 2-carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and the like. .

Regarding the acrylic base polymer, the total amount of the hydroxyl group-containing monomer and the carboxyl group-containing monomer is preferably 1 to 30% by weight, more preferably 2 to 25% by weight, and even more preferably 3 to 20% by weight relative to the total amount of the constituent monomer components. weight%. It is particularly preferable that the content of the carboxyl group-containing monomer is in the above range.

The acrylic base polymer may contain monomer components other than the above. The acrylic base polymer may also contain, for example, vinyl ester monomers, aromatic vinyl monomers, epoxy group-containing monomers, vinyl ether monomers, sulfo group-containing monomers, phosphoric acid group-containing monomers, acid anhydride group-containing monomers etc. as monomer components.

In order to obtain a base polymer substantially free of nitrogen atoms, the constituent monomer components of the base polymer preferably do not contain cyano group-containing monomers, lactam-containing monomers, amide group-containing monomers, morpholine ring-containing monomers, and the like Nitrogen-containing monomers.

The adhesive properties of the adhesive before photocuring are easily affected by the constituents and molecular weight of the base polymer. There is a tendency for the adhesive to become harder as the molecular weight of the base polymer increases. The weight average molecular weight of the acrylic base polymer is preferably 100,000 to 5,000,000, more preferably 300,000 to 3,000,000, and further preferably 500,000 to 2,000,000. In addition, when a crosslinked structure is introduce|transduced into a base polymer, the molecular weight of a base polymer is the molecular weight before the introduction of a crosslinked structure.

Since the base polymer contains a high Tg monomer as a constituent monomer component, the cohesive force of the adhesive is improved, the reworkability before photocuring is excellent, and high adhesiveness after photocuring tends to be exhibited. The high Tg monomer refers to a monomer having a high glass transition temperature (Tg) of a homopolymer. Examples of monomers whose homopolymer Tg is 40°C or higher include cyclohexyl methacrylate (Tg: 66°C), tetrahydrofurfuryl methacrylate (Tg: 60°C), and dicyclopentyl methacrylate. (Tg: 175°C), dicyclopentyl acrylate (Tg: 120°C), isobornyl methacrylate (Tg: 173°C), isobornyl acrylate (Tg: 97°C), methyl methacrylate (Tg: 105°C), 1-adamantyl methacrylate (Tg: 250°C), 1-adamantyl acrylate (Tg: 153°C) and other (meth)acrylates; methacrylic acid (Tg: 228°C) , acrylic acid (Tg: 106 ° C) and other acid monomers.

Regarding the acrylic base polymer, the content of the monomer whose Tg of the homopolymer is 40° C. or higher is preferably 1% by weight or more, more preferably 2% by weight or more, and further preferably 3% by weight with respect to the total amount of the constituent monomer components above. In order to form a pressure-sensitive adhesive layer having moderate hardness and excellent reworkability, the monomer component of the base polymer preferably contains a monomer component having a Tg of a homopolymer of 80° C. or higher, and more preferably contains a Tg of the homopolymer It is a monomer component of 100°C or higher. Regarding the acrylic base polymer, the content of the monomer whose Tg of the homopolymer is 100°C or higher is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and further preferably 1% by weight with respect to the total amount of the constituent monomer components More than 2 weight% or more is especially preferable. On the other hand, from the viewpoint of imparting moderate flexibility to the adhesive, the content of the monomer having a Tg of 40° C. or higher of the homopolymer is preferably 50% by weight or less with respect to the total amount of the constituent monomer components, and more preferably 40% by weight or less, more preferably 30% by weight or less, and may be 20% by weight or less or 10% by weight or less. From the same viewpoint, the content of the monomer whose Tg of the homopolymer is 80°C or higher is preferably 30% by weight or less, more preferably 25% by weight or less, and still more preferably 20% by weight or less with respect to the total amount of the constituent monomer components. , may be 15 wt % or less, 10 wt % or less, or 5 wt % or less.

An acrylic polymer serving as a base polymer can be obtained by polymerizing the above-mentioned monomer components by various known methods such as solution polymerization, emulsion polymerization, and bulk polymerization. The solution polymerization method is preferable from the viewpoints of the balance of properties such as the adhesive force and the holding force of the adhesive, cost, and the like. As the solvent for solution polymerization, ethyl acetate, toluene, or the like can be used. 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 azo-based and peroxide-based ones can be used. In order to adjust the molecular weight, a chain transfer agent can be used. The reaction temperature is usually about 50 to 80°C, and the reaction time is usually about 1 to 8 hours.

(Oligomer)

The adhesive composition may contain oligomers in addition to the base polymer. For example, the adhesive composition may include an acrylic oligomer in addition to the acrylic base polymer. As the oligomer, those having a weight average molecular weight of about 1,000 to 30,000 can be used. The acrylic oligomer contains an alkyl (meth)acrylate as a main constituent monomer component. From the viewpoint of improving the adhesive force of the adhesive layer 2 after photocuring, the glass transition temperature of the acrylic oligomer is preferably 40°C or higher, and more preferably 50°C or higher.

The oligomer may contain a crosslinkable functional group like the base polymer. When the pressure-sensitive adhesive composition contains an oligomer, the oligomer is preferably also substantially free of nitrogen atoms, similarly to the base polymer.

The content of the oligomer in the adhesive composition is not particularly limited. When the adhesive composition contains an acrylic oligomer in addition to the acrylic base polymer, from the viewpoint of adjusting the adhesive force to an appropriate range, the oligomer is 100 parts by weight relative to the base polymer. The amount is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 10 parts by weight, still more preferably 0.5 to 5 parts by weight.

(crosslinking agent)

From the viewpoint of imparting moderate cohesive force to the adhesive, it is preferable to introduce a crosslinked structure into the base polymer. For example, the crosslinked structure is introduced by adding a crosslinking agent to the solution obtained by polymerizing the base polymer, and heating as necessary. The crosslinking agent has two or more crosslinkable functional groups in one molecule. The crosslinking agent may have three or more crosslinkable functional groups in one molecule.

Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, and metal chelate agents. Species cross-linking agent, etc. These crosslinking agents react with functional groups such as hydroxyl groups and carboxyl groups introduced into the base polymer to form a crosslinked structure. Isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred from the viewpoints of high reactivity with hydroxyl groups and carboxyl groups of the base polymer and easy introduction of a crosslinked structure.

As the isocyanate-based crosslinking agent, a polyisocyanate having two or more isocyanate groups in one molecule is used. The isocyanate-based crosslinking agent may have three or more isocyanate groups in one molecule. Examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate. and other alicyclic isocyanates; 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate and other aromatic isocyanates; trimethylolpropane/toluene diisocyanate trimerization Monomer adduct (for example, "Coronate L" manufactured by Tosoh), trimethylolpropane/hexamethylene diisocyanate trimer adduct (for example, "Coronate HL" manufactured by Tosoh), xylylene Isocyanate addition products such as trimethylolpropane adducts of diisocyanate (for example, "Takenate D110N" manufactured by Mitsui Chemicals, isocyanurate bodies of hexamethylene diisocyanate (for example, "Coronate HX" manufactured by Tosoh Corporation), etc. finished product, etc.

As the epoxy-based crosslinking agent, a polyfunctional epoxy compound having two or more epoxy groups in one molecule can be used. The epoxy-based crosslinking agent may have three or more or four or more epoxy groups in one molecule. The epoxy group of the epoxy-based crosslinking agent may be a glycidyl group. Examples of epoxy-based crosslinking agents include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N- Diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol Alcohol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, triglyceride Methylol propane polyglycidyl ether, diglycidyl adipate, diglycidyl phthalate, triglycidyl tris(2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, etc. As the epoxy-based crosslinking agent, commercially available products such as "DENACOL" manufactured by NagaseChemteX Corporation and "Tetrad X" and "Tetrad C" manufactured by Mitsubishi Gas Chemical Company can also be used.

In the case of introducing a crosslinked structure into the base polymer, as described above, if the base polymer does not substantially contain nitrogen atoms, the crosslinking agent may be a substance containing nitrogen atoms such as isocyanate. In the case where the crosslinking agent contains nitrogen atoms, as long as the base polymer does not substantially contain nitrogen atoms, the initial adhesion force to the adherend subjected to surface activation treatment such as plasma treatment can be suppressed low. From the viewpoint of further reducing the difference in initial adhesive strength due to the presence or absence of surface activation treatment, it is preferable that the crosslinking agent also contains substantially no nitrogen atoms, and it is particularly preferable to use an epoxy-based crosslinking agent.

The amount of the crosslinking agent to be used may be appropriately adjusted according to the composition, molecular weight, and the like 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 0.3 to 5 parts by weight relative to 100 parts by weight of the base polymer. In addition, the value obtained by dividing the amount (parts by weight) of the crosslinking agent with respect to 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 0.077, and further It is preferably 0.003 to 0.055, and particularly preferably 0.0045 to 0.044. By making the amount of the crosslinking agent larger than that of the conventional acrylic optical transparent adhesive for permanent bonding and imparting moderate hardness to the adhesive, there is a reduction in the residual adhesive on the adherend during reprocessing, and further Tendency to improve workability.

(Crosslinking accelerator)

The adhesive composition may contain a crosslinking accelerator in addition to the crosslinking agent. By using the crosslinking accelerator, the crosslinking reaction (introduction of the crosslinked structure into the base polymer) can be efficiently advanced. In addition, by introducing a cross-linked structure into the base polymer using a cross-linking accelerator, the adherend whose surface has been activated by the adhesive layer of the reinforcing film tends to exhibit low initial adhesive force.

Examples of the crosslinking accelerator include organometallic compounds such as organometallic complexes (chelate compounds), compounds of metals and alkoxy groups, and compounds of metals and acyloxy groups, and tertiary amines. In particular, the organometallic compound is preferable from the viewpoint of suppressing the progress of the crosslinking reaction in the solution state at room temperature and securing the pot life of the adhesive composition. Moreover, as a crosslinking accelerator, the organometallic compound which is liquid at normal temperature is preferable from the point which is easy to introduce|transduce a uniform crosslinked structure over the whole thickness direction of an adhesive layer.

Examples of the metal of the organometallic compound include iron, tin, aluminum, zirconium, zinc, titanium, lead, cobalt, zinc, and the like.

Examples of the iron-based crosslinking accelerator include tris(acetylacetonato)iron, tris(2,4-hexanedione)iron, tris(2,4-heptanedione)iron, tris(3,5 -Heptanedione)iron, tris(5-methyl-2,4-hexanedione)iron, tris(2,4-octanedione)iron, tris(6-methyl-2,4- Heptanedione) iron, tris(2,6-dimethyl-3,5-heptanedione) iron, tris(2,4-nonanedione) iron, tris(4,6-nonanedione) ) iron, tris (2,2,6,6-tetramethyl-3,5-heptanedione) iron, tris (6,8-tridecanedione) iron, tris (1-phenyl) -1,3-Butanedione) iron, tris (hexafluoroacetylacetonate) iron, tris (ethyl acetoacetate) iron, tris (n-propyl acetoacetate) iron, tris (isopropyl acetoacetate) iron , Tris (n-butyl acetoacetate) iron, tris (sec-butyl acetoacetate) iron, tris (tert-butyl acetoacetate) iron, tris (methyl propionyl acetate) iron, tris (ethyl propionyl acetate) iron , Tris (n-propyl propionyl acetate) iron, tris (isopropyl propionyl acetate) iron, tris (n-butyl propionyl acetate) iron, tris (sec-butyl propionyl acetate) iron, tris (propionyl acetate) tert-butyl)iron, tris(benzyl acetoacetate)iron, tris(dimethylmalonate)iron, tris(diethylmalonate)iron, trimethoxyiron, triethoxyiron, triiso Iron propoxide, etc.

Examples of tin-based crosslinking accelerators include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin maleate, dibutyltin dilaurate, dibutyltin Butyl tin diacetate, dibutyl tin sulfide, tributyl methoxy tin, tributyl tin acetate, triethyl ethoxy tin, tributyl ethoxy tin, dioctyl tin oxide, dioctyl tin Tin laurate, tributyltin chloride, tributyltin trichloroacetate, tin 2-ethylhexanoate, etc.

Examples of the aluminum-based crosslinking accelerator include aluminum mono-sec-butyrate diisopropionate, aluminum sec-butyrate, aluminum isopropionate, aluminum acetate, ethyl acetoacetate aluminum diisopropionate, and tris(ethyl acetoacetate) ) aluminum, alkyl acetoacetate diisopropoxy aluminum, monoacetylacetonate bis(ethyl acetoacetate) aluminum, triacetylacetonate aluminum, etc.

Examples of the zirconium-based crosslinking accelerator include zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium tributoxymonoacetylacetonate, zirconium naphthenate, zirconium propoxide, zirconium butoxide, and the like.

As a zinc type crosslinking accelerator, zinc naphthenate, zinc 2-ethylhexanoate, etc. are mentioned.

Examples of the titanium-based crosslinking accelerator include dibutyltitanium dichloride, tetrabutyl titanate, tetraisopropyl titanate, tetraoctyl titanate, butoxytitanium trichloride, titanium acetylacetonate, Titanium tetraacetylacetonate, titanium ethyl acetoacetate, titanium ammonium lactate chelate, titanium triethanolamine, titanium diisopropoxybisacetylacetonate, titanium isostearate, titanium diethanolamine, titanium aminoethylaminoethanol, etc. .

As a lead-type crosslinking accelerator, lead oleate, lead 2-ethylhexanoate, lead benzoate, lead naphthenate, etc. are mentioned.

Examples of the cobalt-based crosslinking accelerator include cobalt 2-ethylhexanoate, cobalt benzoate, and the like.

The amount of the crosslinking accelerator used may be appropriately adjusted according to the type and amount of the crosslinking agent, and the type of the crosslinking accelerator. The amount of the crosslinking accelerator used is usually about 0.001 to 2 parts by weight relative to 100 parts by weight of the base polymer.

When a crosslinking accelerator is used for the epoxy-based crosslinking agent, the amount of the crosslinking accelerator to be used is preferably 0.01 to 2.0 parts by weight relative to 100 parts by weight of the base polymer. Among the epoxy-based crosslinking agents, non-tin-based organic metals are preferably used as the crosslinking accelerator. When a crosslinking accelerator is used for the isocyanate-based crosslinking agent, the amount of the crosslinking accelerator to be used is preferably 0.001 to 0.1 part by weight.

The adhesive composition may contain a crosslinking retarder in addition to the crosslinking accelerator. By adding the crosslinking retarder, the progress of the crosslinking reaction in the solution state at room temperature can be suppressed, and the pot life of the pressure-sensitive adhesive composition can be extended. Examples of the crosslinking retarder include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and acetoethylstearyl; acetylacetone, 2, β-diketones such as 4-hexanedione and benzoylacetone; alcohols such as tert-butanol. Among them, β-diketone is preferable, and acetylacetone is particularly preferable. The amount of the crosslinking retarder to be used is about 0.1 to 30 parts by weight, preferably 25 parts by weight or less, more preferably 20 parts by weight or less, based on 100 parts by weight of the total amount of the adhesive composition.

(light curing agent)

The adhesive composition constituting the adhesive layer 2 contains a photocuring agent in addition to the base polymer. The adhesive force with the to-be-adhered body improves when the adhesive layer 2 containing the photocurable adhesive composition is adhered to the to-be-adhered body and then photocured.

The photocuring agent has two or more polymerizable functional groups in one molecule. As a polymerizable functional group, it is preferable to have polymerizability by a photoradical reaction, and as a photocuring agent, the compound which has 2 or more of ethylenically unsaturated bonds in 1 molecule is preferable. Furthermore, the photocuring agent is preferably a compound that exhibits compatibility with the base polymer. The photocuring agent is preferably liquid at normal temperature from the viewpoint of exhibiting moderate compatibility with the base polymer. By making the photocuring agent compatible with the base polymer and uniformly dispersing it in the composition, the contact area with the adherend can be secured, and the adhesive layer 2 with high transparency can be formed. In addition, since the base polymer exhibits moderate compatibility with the photocuring agent, it is easy to uniformly introduce the crosslinked structure formed by the photocuring agent into the adhesive layer 2 after photocuring, and there is a possibility of adhesion with the adherend. The tendency for the relay to rise appropriately.

The compatibility of the base polymer with the photocuring agent is mainly affected by the structure of the compound. The structure and compatibility of a compound can be evaluated by, for example, the Hansen solubility parameter, and there is a tendency that the compatibility becomes higher as the difference between the solubility parameters of the base polymer and the photocuring agent is smaller.

From the viewpoint of high compatibility with the acrylic base polymer, it is preferable to use a polyfunctional (meth)acrylate as the photocuring agent. Examples of polyfunctional (meth)acrylates include polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and 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 two Methanol di(meth)acrylate, ethoxylated isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate Meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol poly(meth)acrylate Acrylates, dipentaerythritol hexa(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerol di(meth)acrylate, urethane(meth)acrylate, epoxy(meth)acrylate ) acrylate, butadiene (meth)acrylate, isoprene (meth)acrylate, etc. Among these, polyethylene glycol di(meth)acrylate or polypropylene glycol di(meth)acrylate is preferable, and polyethylene glycol di(meth)acrylate is particularly preferable because of its excellent compatibility with the acrylic base polymer. (Meth)acrylate. A photocuring agent can be used in combination of 2 or more types.

The compatibility of the base polymer with the photocuring agent is also affected by the molecular weight of the compound. There is a tendency that the smaller the molecular weight of the photocurable compound, the higher the compatibility with the base polymer. From the viewpoint of compatibility with the base polymer, the molecular weight of the photocuring agent is preferably 1500 or less, more preferably 1000 or less, still more preferably 500 or less, and particularly preferably 400 or less.

The functional group equivalent (g/eq) of the photocuring agent is preferably 500 or less, more preferably 400 or less, and even more preferably 300, from the viewpoint of high compatibility with the base polymer and improvement of the adhesive strength after photocuring or less, particularly preferably 200 or less. On the other hand, when the functional group equivalent of the photocuring agent is too small, the crosslinking point density of the pressure-sensitive adhesive layer after photocuring becomes high, and the adhesiveness may decrease. Therefore, the functional group equivalent of the photocuring agent is preferably 80 or more, more preferably 100 or more, and still more preferably 130 or more.

In the combination of an acrylic base polymer and a multifunctional acrylate 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 initial adhesion increases, sometimes resulting in Reduced reworkability. From the viewpoint of maintaining the adhesive force between the pressure-sensitive adhesive layer 2 before photocuring and the adherend in an appropriate range, the functional group equivalent of the photocuring agent is preferably within the above range.

The content of the photocuring agent in the adhesive composition is preferably 10 to 50 parts by weight with respect to 100 parts by weight of the base polymer. By making the compounding quantity of a photocuring agent into the said range, the adhesiveness of the pressure-sensitive adhesive layer and to-be-adhered body after photocuring can be adjusted to an appropriate range. The content of the photocuring agent is more preferably 15 to 45 parts by weight, and even more preferably 20 to 40 parts by weight with respect to 100 parts by weight of the base polymer.

(Photopolymerization initiator)

The photopolymerization initiator generates active species by irradiation with actinic rays, and promotes the curing reaction of the photocuring agent. As the photopolymerization initiator, a photocationic initiator (photoacid generator), a photoradical initiator, a photoanionic initiator (photobase generator), etc. can be used according to the type of photocuring agent and the like. When using an ethylenically unsaturated compound, such as a polyfunctional acrylate, as a photocuring agent, it is preferable to use a photoradical initiator as a polymerization initiator.

The photoradical initiator generates radicals by irradiation with actinic rays, and the radicals move from the photoradical initiator to the photocuring agent, thereby promoting the radical polymerization reaction of the photocuring agent. As the photoradical initiator (photoradical generator), a photoradical generator that generates radicals by irradiation with visible light or ultraviolet rays having a wavelength shorter than 450 nm is preferable, and examples thereof include hydroxyketones, benzil diamides Methyl ketals, amino ketones, acyl phosphine oxides, benzophenones, triazine derivatives containing trichloromethyl groups, and the like. The photoradical initiator may be used alone or in combination of two or more.

When transparency is required for the pressure-sensitive adhesive layer 2, it is preferable that the sensitivity of the photopolymerization initiator to light with a wavelength longer than 400 nm (visible light) is small. For example, it is preferable to use an absorption coefficient of 1×10 ² [mLg ^{− 1} cm ^-1 ] or less of a photopolymerization initiator.

The content of the photopolymerization initiator in the adhesive layer 2 is preferably 0.01 to 5 parts by weight, more preferably 0.02 to 3 parts by weight, and even more preferably 0.03 to 2 parts by weight with respect to 100 parts by weight of the base polymer. The content of the photopolymerization initiator in the adhesive layer 2 is preferably 0.02 to 10 parts by weight, more preferably 0.05 to 7 parts by weight, and even more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the photocuring agent.

(other additives)

In addition to the components exemplified above, the pressure-sensitive adhesive layer may contain a silane coupling agent, tackifier, plasticizer, softener, antioxidant, anti-deterioration agent, and filler within a range that does not impair the properties of the present invention , colorants, UV absorbers, surfactants, antistatic agents and other additives.

[Production of Reinforcement Film]

A reinforcement film can be obtained by laminating|stacking the photocurable pressure-sensitive adhesive layer 2 on the film base material 1. The pressure-sensitive adhesive layer 2 may be directly formed on the film base material 1 , or the pressure-sensitive adhesive layer formed in the form of a sheet on another base material may be transferred onto the film base material 1 .

The above-mentioned adhesive composition is applied by roll coating, roll lick coating, gravure coating, reverse coating, roll brush coating, spray coating, dip roll coating, bar coating, blade coating, air knife coating, Curtain coating, lip coating, die coating, etc. are applied on the substrate, and the solvent is dried and removed as necessary, thereby forming an adhesive layer. As a drying method, an appropriate method can be suitably used. The heating drying temperature is preferably 40°C to 200°C, more preferably 50°C to 180°C, and further 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 thickness of the adhesive layer 2 is, for example, about 1 to 300 μm. There is a tendency that the greater the thickness of the pressure-sensitive adhesive layer 2 is, the more the adhesiveness with the adherend is improved. On the other hand, when the thickness of the pressure-sensitive adhesive layer 2 is too large, the fluidity before photocuring is high, and handling may become difficult. Therefore, the thickness of the adhesive layer 2 is preferably 5 to 100 μm, more preferably 8 to 50 μm, still more preferably 10 to 40 μm, and particularly preferably 13 to 30 μm.

When an adhesive composition contains a crosslinking agent, it is preferable to carry out crosslinking by heating or aging simultaneously with drying of a solvent, or after drying of a solvent. The heating temperature and the heating time are appropriately set according to the type of the crosslinking agent to be used, and the crosslinking is usually carried out by heating for about 1 minute to 7 days in the range of 20°C to 160°C. The heating for drying and removing the solvent may also serve as the heating for crosslinking.

By introducing a cross-linked structure into the base polymer, the gel fraction increases. The higher the gel fraction is, the harder the adhesive becomes, and when the reinforcing film is peeled off from the adherend due to reprocessing or the like, there is a tendency to suppress adhesive residue to the adherend. 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 before photocuring of the adhesive layer 2 may be 70% or more or 75% or more.

Since the pressure-sensitive adhesive contains an unreacted photocuring agent, the gel fraction of the pressure-sensitive adhesive layer 2 before photocuring is usually 90% or less. When the gel fraction of the pressure-sensitive adhesive layer 2 before photocuring is too large, the anchoring force to the adherend may decrease, and the initial adhesive force may become insufficient. Therefore, the gel fraction of the pressure-sensitive adhesive layer 2 before photocuring is preferably 85% or less, and more preferably 80% or less.

The gel fraction can be obtained as the insoluble content in a solvent such as ethyl acetate. The weight fraction (unit: weight %) of the sample was calculated|required. In general, the gel fraction of a polymer is equal to the degree of crosslinking, and the more crosslinked parts in the polymer, the higher the gel fraction becomes. Therefore, as the usage-amount of a crosslinking agent (content of a crosslinkable functional group) is large, there exists a tendency for a gel fraction to become large. In addition, by using a crosslinking accelerator, the amount of unreacted functional groups of the crosslinking agent is reduced, so that the gel fraction tends to increase. In the pressure-sensitive adhesive layer 2 before photocuring, since the photocuring agent is in an unreacted state, the greater the amount of the photocuring agent, the smaller the gel fraction.

After the crosslinking structure is introduced into the polymer through the crosslinking agent, the photocuring agent is also maintained in an unreacted state. Therefore, the photocurable adhesive layer 2 containing the base polymer and the photocuring agent is formed. When forming the pressure-sensitive adhesive layer 2 on the film base material 1 , it is preferable to attach the release film 5 to the pressure-sensitive adhesive layer 2 for the purpose of protecting the pressure-sensitive adhesive layer 2 , or the like. After attaching the separator 5 to the pressure-sensitive adhesive layer 2, crosslinking may be performed.

In the case where the adhesive layer 2 is formed on another substrate, a reinforcement film is obtained by transferring the adhesive layer 2 onto the film substrate 1 after drying the solvent. The base material used for formation of the pressure-sensitive adhesive layer may be used as the separator 5 as it is.

As the separator 5, a plastic film such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film can be preferably used. The thickness of the separator is usually 3 to 200 μm, preferably about 10 to 100 μm. The contact surface of the separator 5 with the pressure-sensitive adhesive layer 2 is preferably subjected to a mold release treatment with a silicone-based, fluorine-based, long-chain alkyl-based, or fatty acid amide-based mold release agent, silica powder, or the like. By subjecting the surface of the separator 5 to the mold release treatment, when the film substrate 1 and the separator 5 are peeled off, peeling occurs at the interface between the pressure-sensitive adhesive layer 2 and the separator 5 , and the film substrate 1 is maintained to be fixed. A state in which the adhesive layer 2 is present.

[Use of Enhancement Film]

The reinforcing film of the present invention is used by being attached to a device or a device constituting member. The adherend to which the reinforcement film is attached is not particularly limited, and various electronic devices, optical devices, and constituent members thereof can be exemplified. The reinforcing film can be pasted on the entire surface of the adherend, or can be selectively pasted only on the part that needs to be strengthened. In addition, after sticking the reinforcement film on the entire surface of the adherend, the reinforcement film at the part that does not need reinforcement may be cut, and the reinforcement film may be peeled and removed. Before photocuring the adhesive, since the reinforcement film is temporarily fixed to the surface of the adherend, the reinforcement film can be easily peeled off and removed from the surface of the adherend.

Since moderate rigidity can be imparted by sticking the reinforcing film, it is expected that the operability can be improved and the effect of preventing breakage can be expected. In the manufacturing process of the device, when the reinforcement film is attached to the semi-finished product, the reinforcement film may be attached to the large semi-finished product before being cut into the product size. The reinforcement film can also be applied roll-to-roll to the mother roll of the device manufactured using the roll-to-roll process.

<Characteristics of pressure-sensitive adhesive layer before photocuring>

The pressure-sensitive adhesive layer 2 of the reinforcing film 10 is fixed to the film base material 1 , and the adhesive force to the adherend is small after being adhered to the adherend and before photocuring. Therefore, it is easy to peel the reinforcing film from the adherend before photocuring, and the reworkability is excellent. Further, before photocuring, processing such as cutting the reinforcement film and removing the reinforcement film in a part of the surface of the adherend can be easily performed.

(adhesion)

The adhesive force (initial adhesive force) between the pressure-sensitive adhesive layer 2 before photocuring and the adherend is preferable from the viewpoint of making it easy to peel off the adherend and preventing the adhesive residue to the adherend after peeling the reinforcing film. It is 1 N/25 mm or less, more preferably 0.7 N/25 mm or less, still more preferably 0.5 N/25 mm or less. The adhesive force between the pressure-sensitive adhesive layer 2 before photocuring and the adherend may be 0.4 N/25 mm or less, 0.3 N/25 mm or less, or 0.2 N/25 mm or less. From the viewpoint of preventing peeling of the reinforcement film during storage and handling, the adhesive force between the pressure-sensitive adhesive layer 2 and the adherend before photocuring is preferably 0.005 N/25 mm or more, more preferably 0.01 N/25 mm or more, More preferably, it is 0.02 N/25 mm or more, and particularly preferably 0.03 N/25 mm or more.

It is preferable that the adhesive force with respect to a polyimide film in the state before photocuring the adhesive layer of the reinforcement film exists in the said range. In flexible display panels, flexible printed circuit boards (FPC), and devices in which display panels and circuit boards are integrated, flexible substrate materials are used, and from the viewpoints of heat resistance and dimensional stability, poly Imide film. The reinforcing film having the above-mentioned adhesive force of the adhesive layer with respect to the polyimide film serving as the substrate is easily peeled off before photocuring of the adhesive, and is excellent in adhesion reliability after photocuring.

Before attaching the reinforcing film, the adherend such as the polyimide film on the surface of the device can be activated for the purpose of cleaning or the like. The surface activation treatment includes plasma treatment, corona treatment, glow discharge treatment, and the like. In particular, atmospheric pressure plasma treatment is preferable because it can be processed under atmospheric pressure and has a high activation effect.

When an adherend is subjected to surface activation treatment, there is a tendency that the adhesive force between the pressure-sensitive adhesive layer 2 before photocuring and the adherend becomes higher than when the surface activation treatment is not carried out. When the adhesive force between the pressure-sensitive adhesive layer before photocuring and the adherend is excessively large, reprocessing may become difficult. Therefore, it is preferable that the adhesive force between the adherend that has been subjected to the surface activation treatment and the pressure-sensitive adhesive layer before photocuring is 2 times the adhesive force of the adherend that has not been subjected to the surface activation treatment and the pressure-sensitive adhesive layer before photocuring. times or less, more preferably 1.7 times or less, still more preferably 1.5 times or less.

In the present invention, by making the base polymer of the pressure-sensitive adhesive substantially free of nitrogen atoms, the adhesive force ( initial adhesion) was suppressed lower. Therefore, even when surface activation treatment is performed on an adherend such as a polyimide film, reprocessing is easy in the same manner as in the case where surface activation treatment is not performed.

The adherend whose surface has been activated contains a large number of active groups such as hydroxyl, carbonyl, and carboxyl. When the base polymer contains nitrogen atoms, it can be considered that the unpaired electrons of the nitrogen atoms interact with these active functional groups. , the adhesion is easy to rise. In addition, when the adherend is polyimide, the amic acid, terminal amino group, carboxyl group (or carboxylic acid anhydride group), etc. are activated by the activation treatment, and the interaction with the nitrogen atom is strong, which is also involved in the initial adhesion. The rise of the relay. By making the base polymer substantially free of nitrogen atoms, it is difficult to generate these interactions, so it is presumed that the increase in the initial adhesive force is suppressed.

When the base polymer has a cross-linked structure, the nitrogen atom contained in the isocyanate-based cross-linking agent or the like also increases the initial adhesion force to the surface activation-treated adherend, similarly to the nitrogen atom of the base polymer. , but its effect is small compared to the base polymer. Thus, the crosslinking agent (the crosslinking moiety of the base polymer) may contain nitrogen atoms. Since the crosslinked structure part is easily embedded in the polymer, and the exposure of nitrogen atoms on the surface is small, it is considered that the presence or absence of the surface activation treatment of the adherend has little influence on the change of the initial adhesive force.

By using a crosslinking accelerator such as an organometallic agent, the increase in the initial adhesive force due to the surface activation treatment of the adherend tends to be suppressed, especially the number of crosslinkable functional groups contained in one molecule of the crosslinking agent This tendency is large when there are many and the functional group density is high. When a crosslinking accelerator is used, the crosslinkable functional group is activated, and the reactivity becomes high. Therefore, unreacted functional groups are reduced, the number of polymer chains cross-linked by one cross-linking agent is large, and a high-density cross-linked structure is easily formed, which is considered to contribute to suppressing the increase in initial adhesive force.

For example, when the crosslinking density is low, a photocuring agent (polyfunctional monomer) is likely to exist in the gaps of the polymer chains in the main portion of the pressure-sensitive adhesive layer, and when the crosslinking density is high, it is considered that , the polymer chain has few (small) voids, so it is difficult for the photocuring agent to exist in the main body part, and the photocuring agent is easily distributed near the interface in the adhesive layer before photocuring. Therefore, even when the adherend is subjected to the surface activation treatment, since the interaction between the adherend and the base polymer at the bonding interface is small, the increase in the initial adhesive force can be suppressed.

(storage modulus)

The shear storage elastic modulus G′ _i at 25° C. of the adhesive layer 2 before photocuring is preferably 1×10 ⁴ to 1.2×10 ⁵ Pa. The shear storage modulus (hereinafter abbreviated as "storage modulus") is based on the method described in JIS K7244-1 "Plastics - Test methods for dynamic mechanical properties". The range of 150°C was determined as a value at a predetermined temperature when measured at a temperature increase rate of 5°C/min.

For a substance that exhibits viscoelasticity like an adhesive, the storage modulus G' is used as an index indicating the degree of hardness. The storage 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 layer, the greater the anchoring force to the adherend tends to be. If the storage elastic modulus of the pressure-sensitive adhesive layer 2 before photocuring is 1×10 ⁴ Pa or more, the pressure-sensitive adhesive has sufficient hardness and cohesive force, and therefore, when the reinforcing film is peeled off from the adherend, it is difficult to cause a problem with the adherend. of glue residue. Moreover, when the storage elastic modulus of the adhesive layer 2 is large, it can suppress that an adhesive overflows from the edge surface of a reinforcement film. When the storage modulus of the pressure-sensitive adhesive layer 2 before photocuring 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 it is unlikely to occur even when reprocessing is performed. Cohesive failure of the adhesive layer, adhesive residue on the surface of the adherend.

From the viewpoint of improving the reworkability of the reinforcing film and suppressing the adhesive residue on the adherend during reprocessing, the storage modulus _G'i at 25°C before photocuring of the adhesive layer 2 is more preferably 3× 10 ⁴ to 1×10 ⁵ Pa, more preferably 4×10 ⁴ to 9.5×10 ⁴ Pa.

<Photocuring of pressure-sensitive adhesive layer>

After the reinforcing film is attached to the adherend, the pressure-sensitive adhesive layer 2 is irradiated with actinic rays to photo-cur the pressure-sensitive adhesive layer. Examples of actinic rays include ultraviolet rays, visible rays, infrared rays, X rays, α rays, β rays, and γ rays. From the viewpoint of being able to suppress curing of the pressure-sensitive adhesive layer in a storage state and to facilitate curing, ultraviolet rays are preferred as actinic rays. The irradiation intensity and irradiation time of the actinic ray may be appropriately set according to the composition, thickness, and the like of the pressure-sensitive adhesive layer. Irradiation of the actinic ray to the pressure-sensitive adhesive layer 2 may be performed from either the film substrate 1 side and the adherend side, or the actinic ray may be irradiated from both sides.

<Characteristics of the adhesive layer after photocuring>

(adhesion)

From the viewpoint of adhesion reliability in practical use of the device, the adhesive force between the adhesive layer 2 after photocuring and the adherend is preferably 2 N/25 mm or more, more preferably 3 N/25 mm or more, and further preferably 5 N /25mm or more. The adhesive force between the reinforcing film and the adherend after photocuring the adhesive layer may be 6N/25mm or more, 8N/25mm or more, 10N/25mm or more, 12N/25mm or more, or 13N/25mm or more. In the reinforcement film, it is preferable that the adhesive layer after photocuring has an adhesive force in the above-mentioned range with respect to the polyimide film. The adhesive force between the pressure-sensitive adhesive layer 2 after photocuring and the adherend is preferably 5 times or more, more preferably 8 times or more, and further preferably the adhesive force between the pressure-sensitive adhesive layer 2 and the adherend before photocuring 10 times or more. The adhesive force between the adhesive layer and the adherend after photocuring can be 20 times or more, 30 times or more, 40 times or more, or 50 times the adhesive force between the adhesive layer and the adherend before photocuring above.

As described above, by making the base polymer of the adhesive free of nitrogen atoms, it is possible to suppress an increase in the initial adhesive force due to the surface activation treatment of the adherend. On the other hand, when the adherend was subjected to the surface activation treatment, compared with the case where the surface activation treatment of the adherend was not carried out, the adhesive force between the pressure-sensitive adhesive layer 2 after photocuring and the adherend was present. Tendency to grow larger. That is, in the case of using a reinforcement film having an adhesive layer having a predetermined composition, by subjecting the adherend to surface activation treatment such as plasma treatment, an increase in the initial adhesive force is suppressed, reworkability is ensured, and the A high adhesion force is achieved after curing, and a device excellent in the adhesion reliability of the reinforced film can be obtained. In particular, when the pressure-sensitive adhesive composition contains a crosslinking accelerator such as an organometal, the increase in the initial adhesive strength when the adherend is subjected to a surface activation treatment, and the increase in the adhesive strength after photocuring may become more obvious tendency.

(storage modulus)

The storage elastic modulus G' _f of the adhesive layer 2 at 25° C. after photocuring is preferably 1.0×10 ⁵ Pa or more. When the storage elastic modulus of the pressure-sensitive adhesive layer 2 after photocuring is 1.0×10 ⁵ Pa or more, the adhesive force with the adherend is improved along with the increase in the cohesive force, and high adhesion reliability can be obtained. On the other hand, when the storage modulus is too large, the adhesive becomes difficult to wet and spread, and the contact area with the adherend becomes small. In addition, since the stress dispersibility of the pressure-sensitive adhesive decreases, the peeling force tends to propagate through the adhesive interface, and the adhesive force with the adherend tends to decrease. Therefore, the storage elastic modulus G′ _f at 25° C. after photocuring of the adhesive layer 2 is preferably 2×10 ⁶ Pa or less. From the viewpoint of improving the adhesion reliability of the reinforcement film after photocuring the pressure-sensitive adhesive layer, G' _f is more preferably 1.1×10 ⁵ to 1.2×10 ⁶ Pa, and still more preferably 1.2×10 ⁵ to 1×10 ⁶ Pa.

The ratio G' _f /G' _i of the storage elastic modulus at 25°C before and after photocuring of the adhesive layer 2 is preferably 2 or more. When G' _f is 2 times or more of G' _i , the increase of G' by photocuring will be large, and the reworkability before photocuring and the adhesion reliability after photocuring can be made compatible. G' _f /G' _i is more preferably 4 or more, still more preferably 8 or more, and particularly preferably 10 or more. The upper limit of _{G'f/ G'i} is not particularly limited, but when _G'f / _G'i is too large, initial adhesion failure due to small G' before photocuring, or G' after photocuring is likely to occur. 'Reduced bonding reliability due to excessive size. 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 after the reinforcement film is attached may be subjected to heat treatment such as autoclave treatment for the purpose of improving the affinity of the lamination interface of a plurality of lamination members, and thermocompression bonding for circuit member bonding. In such heat treatment, it is preferable that the adhesive between the reinforcement film and the adherend does not flow from the end surface.

The storage modulus at 100° C. of the adhesive layer 2 after photocuring is preferably 5×10 ⁴ Pa or more, and more preferably 8×10 ⁴ Pa from the viewpoint of suppressing the overflow of the adhesive during high-temperature heating Above, more preferably 1×10 ⁵ Pa or more. The storage modulus at 100° C. of the adhesive layer 2 after photocuring is preferably the storage modulus at 50° C. from the viewpoints of preventing overflow of the adhesive during heating and preventing a decrease in adhesive strength during heating. The modulus is 60% or more, more preferably 65% or more, still more preferably 70% or more, and particularly preferably 75% or more.

By attaching the reinforcing film, moderate rigidity can be imparted to the semi-finished product as an adherend, and stress can be relaxed and dispersed. Therefore, various failures that may occur in the manufacturing process can be suppressed, production efficiency can be improved, and yield can be improved. . In addition, even when the adherend is subjected to surface activation treatment, the reinforcement film is easily peeled from the adherend before photocuring the pressure-sensitive adhesive layer, so it is also difficult to laminate and stick. Easy to rework. After photocuring the pressure-sensitive adhesive layer, high adhesive force is exhibited to the adherend, the reinforcing film is not easily peeled from the device surface, and the adhesion reliability is excellent.

Example

The following examples are given for further description, but the present invention is not limited to these examples.

[Example 1]

<Polymerization of base polymer>

95 parts by weight of butyl acrylate (BA) and 5 parts by weight of acrylic acid (AA) as monomers, and azobisiso as a thermal polymerization initiator were put into a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen introduction tube. 0.2 parts by weight of nitrile (AIBN) and 233 parts by weight of ethyl acetate as a solvent were poured into nitrogen gas, and nitrogen substitution was performed for about 1 hour while stirring. Then, it heated to 60 degreeC, it was made to react for 7 hours, and the solution of the acrylic polymer with a weight average molecular weight of 600,000 was obtained.

<Preparation of adhesive composition>

To the solution of the acrylic polymer was added 0.5 parts by weight of a tetrafunctional epoxy compound (“Tetrad C” manufactured by Mitsubishi Gas Chemical Company) as a crosslinking agent, and a polyfunctional acrylic monomer manufactured by Shin-Nakamura Chemical Industry Co., Ltd. "NK ESTER A200" (polyethylene glycol #200 (n=4) diacrylate; molecular weight 308, functional group equivalent 154 g/eq) 30 parts by weight, and a photopolymerization initiator ("Irgacure651" manufactured by BASF Corporation) 0.1 parts by weight to prepare the adhesive composition.

<Coating and Crosslinking of Adhesive Composition>

On a polyethylene terephthalate film (“Lumirror S10” manufactured by Toray Industries Ltd.) having a thickness of 75 μm without surface treatment, the above-mentioned adhesive composition was applied using a feed roller so that the thickness after drying would be 25 μm. . After drying at 130° C. for 1 minute to remove the solvent, a release film (polyethylene terephthalate film with a thickness of 25 μm on which the surface was subjected to a silicone mold release treatment) was attached to the application surface of the adhesive. Molded surface. Then, aging treatment was performed in an environment of 25° C. for 4 days to advance crosslinking, thereby obtaining a reinforcing film in which the photocurable pressure-sensitive adhesive sheet was fixed and laminated on the film substrate, and the separator was temporarily fixed thereon.

[Examples 2 to 6]

In the preparation of the adhesive composition, in addition to the crosslinking agent, the polyfunctional acrylic monomer, and the photopolymerization initiator, the type and amount of organic compounds shown in Table 1 were added to the solution of the acrylic polymer. Metal crosslinking accelerator. A reinforced thin film was produced in the same manner as in Example 1 except that the organometallic crosslinking accelerator was added.

[Example 7 and Example 8]

In Example 7, in the preparation of the adhesive composition, in addition to the crosslinking agent, the multifunctional acrylic monomer, and the photopolymerization initiator, in the solution of the acrylic polymer, a carboxyl group-containing acrylic low 1 part by weight of polymer (“ARUFON UC-3000” manufactured by Toagosei Co., Ltd.; weight average molecular weight: 10,000, glass transition temperature: 65° C., acid value: 74 mgKOH/g). In Example 8, an organometallic crosslinking accelerator was further added. Except these changes, it carried out similarly to Example 1, and produced the reinforcement film.

[Example 9]

In the preparation of the adhesive composition, as the photopolymerization initiator, "Irgacure 184" manufactured by BASF Corporation was used instead of "Irgacure 651" manufactured by BASF Corporation. Other than that, it carried out similarly to Example 1, and produced the reinforcement film.

[Example 10]

In the polymerization of the base polymer, the charging ratio of the monomers was changed to BA: 90 parts by weight and AA: 10 parts by weight. Other than that, it carried out similarly to Example 9, and produced the reinforcement film.

[Comparative Example 1]

<Polymerization of base polymer>

63 parts by weight of 2-ethylhexyl acrylate (2EHA), 9 parts by weight of methyl methacrylate (MMA), acrylic acid hydroxyl group as monomers were put into a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas introduction pipe. 13 parts by weight of ethyl ester (HEA), 15 parts by weight of N-vinylpyrrolidone (NVP), 0.2 parts by weight of AIBN as a thermal polymerization initiator, and 233 parts by weight of ethyl acetate as a solvent, nitrogen gas was flowed, and stirred Nitrogen replacement was performed for about 1 hour. Then, it heated at 60 degreeC, it was made to react for 7 hours, and the solution of the acrylic polymer with a weight average molecular weight of 1,200,000 was obtained.

<Preparation of adhesive composition>

A 75% ethyl acetate solution ("Takenate D110N" manufactured by Mitsui Chemicals Co., Ltd.) of a trimethylolpropane adduct of xylylene diisocyanate as a crosslinking agent was added to the acrylic polymer solution to form a solid 2.5 parts by weight in terms of components, "NK ESTERAPG700" (polypropylene glycol #700 (n=12) diacrylate; molecular weight 808, functional group equivalent 404 g/eq) manufactured by Shin-Nakamura Chemical Industry Co., Ltd. as a polyfunctional acrylic monomer 30 Parts by weight and 1 part by weight of a photopolymerization initiator ("Irgacure 184" manufactured by BASF) were used to prepare an adhesive composition.

<Coating and Crosslinking of Adhesive Composition>

Coating, heat drying, and crosslinking of the pressure-sensitive adhesive composition were carried out in the same manner as in Example 1 to produce a reinforcing film in which a photocurable pressure-sensitive adhesive sheet was fixedly laminated on a film substrate, and a release film was temporarily fixed thereon. .

[Comparative Example 2 and Comparative Example 3]

In the preparation of the adhesive composition, in addition to the crosslinking agent, the polyfunctional acrylic monomer, and the photopolymerization initiator, the type and amount of organic compounds shown in Table 1 were added to the solution of the acrylic polymer. Metal crosslinking accelerator. A reinforced thin film was produced in the same manner as in Comparative Example 1 except that the organometallic crosslinking accelerator was added.

[Comparative Example 4]

In the preparation of the adhesive composition, as the photopolymerization initiator, "Irgacure 651" manufactured by BASF Corporation was used instead of "Irgacure 184" manufactured by BASF Corporation. Except for this, a reinforcement film was produced in the same manner as in Comparative Example 2.

[Comparative Example 5]

In the preparation of the adhesive composition, as a multifunctional acrylic monomer, 20 parts by weight of "NK ESTER A200" manufactured by Shin-Nakamura Chemical Industry Co., Ltd. was added instead of "NK ESTERAPG700" manufactured by Shin-Nakamura Chemical Co., Ltd. for 30 parts by weight. parts by weight. Other than that, it carried out similarly to the comparative example 2, and produced the reinforcement film.

[Measurement of Adhesion to Polyimide Film]

<Adhesion before photocuring>

A polyimide film (“Kapton 50EN” manufactured by DU PONT-TORAY) with a thickness of 12.5 μm was attached to a glass plate with a double-sided tape (“No. 531” manufactured by Nitto Denko Corporation) to obtain a polyimide for measurement thin film substrate. The separator was peeled and removed from the surface of the reinforcement film cut out to a width of 25 mm×length of 100 mm, and was adhered to a polyimide film substrate for measurement using a hand-pressed roller to prepare a sample for measurement of adhesive force (no plasma treatment). ).

While conveying the polyimide substrate for measurement at a conveying speed of 3 m/min, a plasma treatment was performed on the surface of the polyimide film under the condition of an electrode voltage of 160 V using an atmospheric pressure plasma processor. On the polyimide film substrate for measurement after the plasma treatment, a reinforcing film was pasted using a hand press roll to prepare a sample for measuring the adhesive force (with plasma treatment).

Using these test samples, the end of the polyethylene terephthalate film of the reinforcement film was held by a chuck, and the 180° peel test of the reinforcement film was performed at a tensile speed of 300 mm/min, and the peel strength was measured. From the obtained results, the ratio of the adhesive force with the plasma treatment to the adhesive force without the plasma treatment (the increase rate of the adhesive force due to the plasma treatment) was calculated.

<Adhesion after photocuring>

After attaching the enhancement film to the polyimide film substrate (with plasma treatment and without plasma treatment), irradiating the side of the enhancement film (the side of the PET film) with an LED light source with a wavelength of 365 nm with a cumulative light intensity of 4000 mJ/cm ² of ultraviolet rays The adhesive layer is photocured. Using this test sample, the adhesive force was measured by the 180° peel test in the same manner as described above.

The composition of the adhesive of each reinforcing film, the adhesion to the polyimide film, and the increase rate of the adhesion due to plasma treatment (the adhesion of "with plasma treatment" relative to "without plasma treatment") were compared. Table 1 shows the adhesive force ratio after photocuring. The addition amount in the composition of Table 1 is the addition amount (weight part) with respect to 100 weight part of base polymers.

In Table 1, "UC3000" is "ARUFON UC-3000" manufactured by Toagosei Co., Ltd., "A200" is "NK ESTER A200" manufactured by Shin-Nakamura Chemical Industry Co., Ltd., and "APG700" is manufactured by Shin-Nakamura Chemical Industry Co., Ltd. "NK ESTER APG700", "Irg651" are "Irgacure651" manufactured by BASF Corporation, and "Irg184" are "Irgacure184" manufactured by BASF Corporation. Details of the crosslinking accelerators in Table 1 are as follows.

Fe: tris(acetylacetonate) iron ("FerricAcetylacetonate" manufactured by Nippon Chemical Industry Co., Ltd.)

Zr: Zirconium tetraacetylacetonate (manufactured by Tokyo Chemical Industry Co., Ltd.)

Ti: Diisopropoxybisacetylacetonate titanium (manufactured by Tokyo Chemical Industry Co., Ltd.)

Al: Aluminum triacetylacetonate (manufactured by Tokyo Chemical Industry Co., Ltd.)

Sn: Dioctyl tin laurate ("EMBILIZER OL-1" manufactured by Tokyo Fine Chemical CO., LTD.)

【Table 1】

In any of the Examples and Comparative Examples, the initial adhesion force to the polyimide film substrate not subjected to the plasma treatment was 0.5 N/25 mm or less, and the polyimide film could be easily peeled off. In addition, when the adhesive is photocured, the adhesive force is increased, and the adhesive is firmly adhered to the polyimide film substrate.

In Comparative Example 1 using the base polymer containing N-vinylpyrrolidone as a monomer component, the initial adhesion force to the polyimide film substrate after the plasma treatment increased to that of the polyimide not subjected to the plasma treatment. The initial adhesion strength of the amine film substrate is more than 4 times, and it is difficult to peel the reinforcing film from the polyimide film substrate.

In Comparative Examples 2 to 4 to which the crosslinking accelerator was added, compared with Comparative Example 1, the increase in the initial adhesive force due to the plasma treatment was suppressed, but the increase was higher than that of the polyimide not subjected to the plasma treatment. The initial adhesion strength of the film substrate is more than 2 times.

In Example 1 using the base polymer composed of butyl acrylate and acrylic acid as monomer components, the initial adhesion force to the polyimide film substrate after the plasma treatment was the same as that of the polyimide without plasma treatment. The initial adhesion force of the amine thin film substrate was 1.4 times higher, and the increase in the initial adhesion force caused by the plasma treatment was suppressed. In Examples 2 to 6 to which the crosslinking accelerator was added, compared with Example 1, the increase in the initial adhesive force was further suppressed.

In Examples 7 and 8 in which an acrylic oligomer was added in addition to the acrylic base polymer, the increase in the initial adhesive force due to the plasma treatment was suppressed, and a further increase in the crosslinking accelerator was observed by adding a crosslinking accelerator. The tendency to increase the initial adhesive force is suppressed. In Example 9 in which the type of the photopolymerization initiator was changed, and in Example 10 in which the charge ratio of the monomer in the base polymer was changed, the initial adhesion due to the plasma treatment was suppressed as in the other examples. strength rises.

When focusing on the adhesive force after photocuring the adhesive, in any of the examples, by attaching a reinforcing film to the polyimide substrate after the plasma treatment and photocuring it, it can be compared with the non-plasma treated polyimide substrate. Compared with the case, the adhesive force increased.

From the above results, it can be seen that, for the reinforcement film including the photocurable adhesive in which the base polymer does not contain nitrogen atoms, the initial adhesive strength to the adherend subjected to activation treatment such as plasma treatment is low, and the It is excellent in workability, exhibits high adhesion to an adherend after photocuring, and is excellent in adhesion reliability.

Claims (14)

1. A reinforced film comprising a film base and an adhesive layer fixedly laminated on one main surface of the film base,

the adhesive layer comprises a photocurable composition containing an acrylic base polymer, a photocuring agent, and a photopolymerization initiator,

the acrylic base polymer contains 1 or more monomer units selected from the group consisting of hydroxyl group-containing monomers and carboxyl group-containing monomers, and contains 1 to 10% by weight of a monomer component having a homopolymer Tg of 40 ℃ or higher,

the proportion of nitrogen atoms in the constituent elements of the acrylic base polymer is 0.01 mol% or less,

the acrylic base polymer has a crosslinked structure introduced by a crosslinking agent bonded to the hydroxyl group or the carboxyl group.

2. The reinforced film of claim 1, wherein the crosslinker is free of nitrogen atoms.

3. The reinforced film of claim 1, wherein the crosslinker is an epoxy-based crosslinker.

4. A reinforced film according to any one of claims 1 to 3, wherein the base polymer having a crosslinked structure is formed by a crosslinking reaction of a composition comprising an acrylic base polymer, the crosslinking agent and an organometallic crosslinking promoter.

5. The reinforcing film according to any one of claims 1 to 3, wherein the gel fraction of the photocurable composition is 60% or more.

6. The reinforced film according to any one of claims 1 to 3, wherein the photocurable composition contains 10 to 50 parts by weight of the photocurable agent per 100 parts by weight of the acrylic base polymer.

7. A reinforced film according to any one of claims 1 to 3, wherein the photocuring agent is a multifunctional (meth) acrylate.

8. The reinforcing film according to any one of claims 1 to 3, wherein the photocuring agent has a functional group equivalent of 100 to 500 g/eq.

9. The reinforcing film according to any one of claims 1 to 3, wherein the adhesion force with the polyimide film before photocuring of the adhesive layer is 1N/25mm or less.

10. A method for manufacturing a device having a reinforcing film adhered to a surface thereof,

temporarily fixing the adhesive layer of the reinforcing film according to any one of claims 1 to 9 to the surface of an adherend, and then,

the pressure-sensitive adhesive layer is irradiated with an actinic ray to photocure the pressure-sensitive adhesive layer, thereby increasing the adhesion of the reinforcing film to the adherend.

11. The method for manufacturing a device according to claim 10, wherein a surface activation treatment of the adherend is performed before the reinforcing film is temporarily fixed.

12. The method of manufacturing a device according to claim 11, wherein the surface activation treatment is a plasma treatment.

13. The method for manufacturing a device according to any one of claims 10 to 12, wherein the adherend is a polyimide film.

14. A reinforcing method for sticking a reinforcing film to the surface of an adherend, wherein,

temporarily fixing the pressure-sensitive adhesive layer of the reinforcing film according to any one of claims 1 to 9 to the surface of an adherend after activation treatment of the surface of the adherend,

the pressure-sensitive adhesive layer is irradiated with an actinic ray to photocure the pressure-sensitive adhesive layer, thereby increasing the adhesion of the reinforcing film to the adherend.

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