TW202041633A - Reinforcing film, method for making same, method for making device and reinforcing method - Google Patents

Abstract

The invention provides a reinforcing film, a method for making the same, a method for making a device and a reinforing method. The present invention relates to the reinforcing film (10) comprising: a film substrate; and an adhesive layer (2) adhered and laminated on one main surface of the film substrate, wherein the adhesive layer consists of a photocurable composition. In addition, the photocurable composition constituting the adhesive layer comprises a base polymer, a photo-curing agent, and a photopolymerization initiator. The base polymer having a cross-linked structure is formed by a cross-linking reaction of a composition including the base polymer, a cross-linking agent, and a cross-linking accelerator.

Description

Reinforcing film and its manufacturing method, manufacturing method and reinforcing method of device

The present invention relates to a reinforcing film formed by fixing and laminating a film substrate and a photocurable adhesive layer and a manufacturing method thereof. Furthermore, the present invention relates to a method of manufacturing a device with a reinforcing film attached to the surface, and a reinforcing method of fixing a laminated reinforcing film on the surface of an adherend.

On the surface of an optical device such as a display or an electronic device, an adhesive film may be attached for surface protection or impact resistance. Such an adhesive film is usually fixed with a laminated adhesive layer on the main surface of the film substrate, and is attached to the surface of the device via the adhesive layer.

In the state before the device is assembled, processed, transported, etc., the adhesive film can be temporarily adhered to the surface of the device or its constituent parts to prevent damage or breakage of the adherend. For such an adhesive film temporarily adhered for the purpose of temporary protection of the surface, it is required that it can be easily peeled off from the adherend and does not produce paste residue on the adherend.

Patent Document 1 discloses an adhesive film, which, in addition to the assembly, processing, and transportation of the device, is also used in a state of being attached to the surface of the device during use of the device. Such an adhesive film has the function of reinforcing the device due to surface protection, dispersion of the impact on the device, and rigidity to the flexible device.

When the adhesive film is attached to the adherend, there are cases of poor attachment such as the mixing of air bubbles or the offset of the attachment position. In the case of poor bonding, perform the following operations (secondary processing): peel the adhesive film from the adherend and attach another adhesive film. The adhesive film used as an engineering material is designed on the premise of peeling from the adherend, so it is easy to reprocess. On the other hand, the reinforcing film premised on permanent bonding generally does not assume peeling from the device but firmly adheres to the surface of the device, so it is difficult to perform secondary processing.

Patent Document 2 discloses an adhesive film provided with an adhesive layer designed to have low adhesiveness immediately after being bonded to an adherend, and then the force to increase over time. The adhesive that uses light or heat as the trigger to increase the adhesive force can be arbitrarily set at the time point of the adhesive force rising due to hardening after being attached to the adherend. In addition, since the adhesive force is small immediately after bonding (before the adhesive force increasing process), it is easy to peel off from the adherend, and can be used as a reinforcing film with secondary processability. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2017-132977 [Patent Document 2] International Publication No. 2015/163115

[The problem to be solved by the invention]

There are cases where the surface of an adherend such as a plasma device or the like is subjected to surface activation treatment such as plasma treatment or corona treatment for the purpose of cleaning the surface of the adherend before laminating the reinforcing film. If the reinforcing film is attached to the surface of the adherend after the surface activation treatment, the adhesive strength will increase significantly compared with the case where the adherend without the surface activation treatment is attached to the reinforcing film, and the reinforcement will be peeled off from the adherend. When the film (secondary processing) becomes difficult.

In view of this problem, the object of the present invention is to provide a reinforcing film that has low initial adhesion to the adherend and excellent secondary processability even when the surface of the adherend is activated by plasma or the like. . [Technical means to solve the problem]

In view of the above-mentioned problems, the inventors of the present invention conducted research and found that by using a cross-linking accelerator to introduce a cross-linked structure into the base polymer, the initial adhesive strength is poor due to the presence or absence of surface activation treatment of the adherend Smaller, it also has excellent secondary processability to the adherend after surface activation treatment.

The reinforcing film of the present invention is provided with an adhesive layer fixedly laminated on a main surface of the film substrate. The adhesive layer contains a photocurable composition, and the photocurable composition contains a base polymer having a crosslinked structure, a photocuring agent, and a photopolymerization initiator. For example, a composition containing a base polymer, a crosslinking agent, a crosslinking accelerator, a light hardener, and a photopolymerization initiator is applied to a film substrate in a layered manner, and a combination of the base polymer and the crosslinking agent is used. The reaction introduces a cross-linked structure into the base polymer, thereby obtaining a reinforced film with an adhesive layer fixed on the film substrate. The adhesive layer formed on other substrates can also be transferred to the film substrate.

As the base polymer of the adhesive layer, for example, an acrylic polymer can be used. The crosslinking structure is introduced into the base polymer by the crosslinking reaction of the composition including the base polymer, the crosslinking agent, and the crosslinking accelerator. For example, the base polymer contains a hydroxyl group-containing monomer and/or a carboxyl group-containing monomer as a monomer unit, and is cross-linked by bonding a cross-linking agent such as a multifunctional isocyanate compound or a multifunctional epoxy compound to these functional groups. structure. As a crosslinking accelerator, an organometallic compound can be used favorably. By making the adhesive composition include a base polymer with a cross-linked structure introduced with a cross-linking accelerator, even when the surface of the adherend is activated by plasma treatment or the like, it is suppressed The tendency of the initial adhesion of the adhesive body to increase.

The gel fraction of the adhesive layer (photocurable composition) can be 60% or more.

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

After the reinforcing film is temporarily adhered to the surface of the adherend, the adhesive layer is irradiated with active light to light-harden the adhesive layer, so that the adhesive force between the reinforcing film and the adherend increases, and is obtained on the surface of the adherend The fixed laminate has a device for reinforcing film. When the adherend is a polyimide film, it is preferable that the adhesive force between the adhesive layer and the polyimide film be 1 N/25 mm or less before the adhesive layer is photocured (temporary adhesion state). It is also possible to perform surface activation treatments such as plasma treatment on the adherend before temporarily adhering the reinforcing film to the adherend. [Effects of Invention]

In the reinforcing film of the present invention, the adhesive layer contains a photocurable composition, and after bonding with the adherend, the adhesive layer is photocured to increase the adhesive force with the adherend. Before the adhesive layer is photocured, the adhesive force to the adherend that has been activated by plasma treatment or the like is also small, so it is easy to perform secondary processing, and exhibits a higher adhesive force after photocuring.

Fig. 1 is a cross-sectional view showing an embodiment of a reinforcing film. The reinforcing film 10 is provided with an adhesive layer 2 on one main surface of the film base material 1. The adhesive layer 2 is fixedly laminated on one main surface of the base film 1. The adhesive layer 2 contains a photocurable adhesive of a photocurable composition, and is cured by the irradiation of active rays such as ultraviolet rays, thereby increasing the adhesive force with the adherend.

2 is a cross-sectional view of a reinforcing film with a spacer 5 temporarily adhered to the main surface of the adhesive layer 2. 3 is a cross-sectional view showing a state where the reinforcing film 10 is attached to the surface of the device 20.

The spacer 5 is peeled off from the surface of the adhesive layer 2, and the exposed surface of the adhesive layer 2 is attached to the surface of the device 20, thereby attaching the reinforcing film 10 to the surface of the device 20. This state is that the adhesive layer 2 is in a state where the reinforcing film 10 (adhesive layer 2) is temporarily adhered to the device 20 before photocuring. By photocuring the adhesive layer 2, the adhesive force at the interface between the device 20 and the adhesive layer 2 is increased, and the device 20 and the reinforcing film 10 are fixed.

The so-called "fixed" refers to the state where the two layers of the laminated layer are firmly connected, and it is impossible or difficult to peel off at the interface between the two layers. The so-called "temporary adhesion" refers to a state in which the adhesive force between the two layers of the laminated layer is small and can be easily peeled off at the interface between the two layers.

In the reinforced film shown in FIG. 2, the film base material 1 and the adhesive layer 2 are fixed, and the spacer 5 is temporarily adhered to the adhesive layer 2. When the film base material 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 of the adhesive layer 2 fixed on the film base material 1 is maintained. No adhesive remains on the separator 5 after peeling.

In the pasting device shown in FIG. 3 provided with a reinforcing film 10, before the photo-curing of the adhesive layer 2, the device 20 and the adhesive layer 2 are in a temporarily bonded state. If the film base material 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 of the adhesive layer 2 fixed on the film base material 1 is maintained. Since no adhesive remains on the device 20, secondary processing is easy. After the adhesive layer 2 is photocured, since the adhesive force between the adhesive layer 2 and the device 20 increases, it is difficult to peel the film 1 from the device 20. If the two are peeled off, the adhesive layer 2 may cause aggregation failure .

[Composition of Reinforcing Film] ＜Film base material＞ As the film base material 1, a plastic film is used. In order to fix the film base material 1 and the adhesive layer 2, it is preferable that the surface of the film base material 1 on which the adhesive layer 2 is attached has not been subjected to mold release treatment.

The thickness of the film substrate is, for example, about 4 to 500 μm. From the viewpoint of reinforcement of the device by rigidity imparting or impact mitigation, 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 making the reinforcing film flexible and improving operability, the thickness of the film substrate 1 is preferably 300 μm or less, and more preferably 200 μm or less. From the viewpoint of both mechanical strength and flexibility, the compressive strength of the film substrate 1 is preferably 100-3000 kg/cm ² , more preferably 200-2900 kg/cm ² , and still more preferably 300-2800 kg /cm ² , preferably 400～2700 kg/cm ² .

Examples of the plastic material constituting the film base material 1 include polyester resins, polyolefin resins, cyclic polyolefin resins, polyamide resins, polyimide resins, and the like. In reinforcing films for optical devices such as displays, the film substrate 1 is preferably a transparent film. In addition, when active light rays are irradiated from the side of the film base material 1 to perform photocuring of the adhesive layer 2, the film base material 1 preferably has transparency to the active light rays used for curing the adhesive layer. In terms of having both mechanical strength and transparency, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate can be used favorably. When the active light is irradiated from the side of the adherend to harden the adhesive layer, the adherend only needs to be transparent to the active light, and the film substrate 1 may be opaque to the active light.

Functional coatings such as an easy-to-adhesive layer, easy-slip layer, release layer, antistatic layer, hard coating layer, and anti-reflection layer can also be provided on the surface of the film substrate 1. Furthermore, as described above, in order to fix the film base material 1 and the adhesive layer 2, it is preferable that no release layer is provided on the surface of the film base material 1 where the adhesive layer 2 is attached.

＜Adhesive layer＞ The adhesive layer 2 fixedly laminated on the film substrate 11 includes a photocurable composition containing a base polymer, a photocuring agent, and a photopolymerization initiator. Since the adhesive layer 2 has a small adhesive force with the adhered body such as the device or device parts before photocuring, secondary processing is easy. Since the adhesive force of the adhesive layer 2 with the adherend is improved by light curing, the reinforcing film is not easy to peel off from the surface of the device when the device is used, and the bonding 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 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 component of the adhesive composition. The type of base polymer is not particularly limited, and acrylic polymer, silicone polymer, urethane polymer, rubber polymer, etc. may be appropriately selected. Especially in terms of excellent optical transparency and adhesiveness, and easy control of adhesiveness, the adhesive composition preferably contains an acrylic polymer as a base polymer, and is preferably 50% by weight of the adhesive composition % Or more is acrylic polymer.

As the acrylic polymer, those containing alkyl (meth)acrylate as a main monomer component can be used favorably. In addition, in this specification, "(meth)acrylic acid" means acrylic acid and/or methacrylic acid.

As the alkyl (meth)acrylate, an alkyl (meth)acrylate whose alkyl group has 1 to 20 carbon atoms can be preferably 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) ) Second butyl acrylate, third butyl (meth)acrylate, pentyl (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) 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, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, (meth)acrylic acid Aralkyl esters and the like.

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

The acrylic base polymer contains a monomer component having a crosslinkable functional group as a copolymer component. Due to the introduction of a cross-linked structure in the base polymer, the cohesive force increases, the adhesive force of the adhesive layer 2 increases, and the paste residue on the adherend during secondary processing tends to decrease.

Examples of the monomer having a crosslinkable functional group include a hydroxyl group-containing monomer or a carboxyl group-containing monomer. The hydroxyl group or carboxyl group of the base polymer becomes the reaction point with the crosslinking agent mentioned later. For example, when an isocyanate-based crosslinking agent is used, it is preferably a copolymerization component containing a hydroxyl-containing monomer as a base polymer. When an epoxy-based crosslinking agent is used, it is preferably a copolymer component containing a carboxyl group-containing monomer as a base polymer.

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. Ester, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, 4-(hydroxymethyl)cyclohexylmethyl (meth)acrylate Ester etc. Examples of carboxyl group-containing monomers include (meth)acrylic acid, 2-carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, Butenoic acid and so on.

In 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 still more preferably 3 relative to the total amount of constituent monomer components. ~20% by weight.

The acrylic base polymer may also contain N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperidine, vinylpyrrolidone, vinyl Nitrogen-containing monomers such as pyrrole, vinyl imidazole, vinyl azole, vinyl oxoline, N-acryloyl oxoline, N-vinyl carboxamides, and N-vinyl caprolactam as constituent monomers ingredient.

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

The base polymer before the introduction of the cross-linked structure may be substantially free of nitrogen atoms. The ratio of nitrogen in the constituent elements of the base polymer may be 0.1 mol% or less, 0.05 mol% or less, 0.01 mol% or less, 0.005 mol% or less, 0.001 mol% or less, or 0. By using a base polymer that does not substantially contain nitrogen atoms, there is a tendency to suppress the increase in the adhesive force (initial adhesive force) of the adhesive layer before photocuring when the surface activation treatment is performed on the adherend.

By not using nitrogen atom-containing monomers such as cyano group-containing monomers, internal amide structure monomers, amine group-containing monomers, and pholine ring-containing monomers as the constituent monomer components of the basic polymer, the essential The base polymer does not contain nitrogen atoms. In the case where the base polymer does not substantially contain nitrogen atoms, from the viewpoint of improving the cohesiveness of the adhesive, the base polymer also preferably contains a carboxyl group-containing monomer as a monomer component.

The adhesive properties of the adhesive before photocuring are easily affected by the composition and molecular weight of the base polymer. The greater the molecular weight of the base polymer, the harder the adhesive tends to become. The weight average molecular weight of the acrylic base polymer is preferably 100,000 to 5 million, more preferably 300,000 to 3 million, and still more preferably 500,000 to 2 million. Furthermore, when a cross-linked structure is introduced into the base polymer, the molecular weight of the base polymer refers to the molecular weight before the introduction of the cross-linked structure.

By including a high Tg monomer as a constituent monomer component in the base polymer, there is a tendency that the cohesive force of the adhesive is improved, the secondary processability before photocuring is excellent, and the adhesion reliability after photocuring is higher. The so-called high Tg monomer means a monomer with a higher glass transition temperature (Tg) of the homopolymer. Monomers with homopolymers having a Tg of 40°C or higher include: dicyclopentyl methacrylate (Tg: 175°C), dicyclopentyl acrylate (Tg: 120°C), and iso-methacrylate (Tg: 173°C), isopropyl 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; acrylamide (Tg: 145°C), dimethyl acrylamide (Tg: 119°C), diethyl acrylamide (Tg: 81°C) , Dimethylaminopropyl acrylamide (Tg: 134°C), isopropylacrylamide (Tg: 134°C), hydroxyethyl acrylamide (Tg: 98°C) and other vinyl groups containing amide groups Monomers; acid monomers such as methacrylic acid (Tg: 228°C) and acrylic acid (Tg: 106°C); N-vinylpyrrolidone (Tg: 54°C) and the like.

In the acrylic base polymer, the content of the monomer whose Tg of the homopolymer is 40° C. or higher is preferably 1 to 50% by weight, and more preferably 3 to 40% by weight, relative to the total amount of constituent monomer components. In order to form an adhesive layer with moderate hardness and excellent secondary processability, the monomer component of the base polymer preferably includes a monomer component with a homopolymer having a Tg of 80°C or higher, and more preferably includes a homopolymer The Tg of the material is a monomer component above 100°C. In the acrylic base polymer, the content of the monomer having a Tg of 100°C or higher in the homopolymer is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and more preferably 1 % By weight or more, particularly preferably 3% by weight or more.

By polymerizing the above-mentioned monomer components by various known methods such as solution polymerization, emulsion polymerization, and bulk polymerization, an acrylic polymer as a base polymer can be obtained. From the viewpoint of the balance of properties such as adhesive force and retention force of the adhesive, or the viewpoint of cost, the solution polymerization method is preferred. As a solvent for solution polymerization, ethyl acetate, toluene, etc. are used. The concentration of the solution is usually about 20 to 80% by weight. As the polymerization initiator used in the solution polymerization, various known ones such as azo-based and peroxide-based 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 include oligomers in addition to the base polymer. For example, the adhesive composition may include acrylic oligomers 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 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, more preferably 50°C or higher. Like the base polymer, the oligomer may contain a functional group capable of crosslinking.

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

(Crosslinking agent) By introducing a cross-linked structure into the base polymer, the adhesive can have a moderate cohesive force. For example, a crosslinking structure is introduced by adding a crosslinking agent to the solution after 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 3 or more crosslinkable functional groups in one molecule.

Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, azoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, and metal chelate compounds. Department of crosslinking agent and so on. These crosslinking agents react with functional groups such as hydroxyl or carboxyl groups introduced into the base polymer to form a crosslinked structure. In terms of high reactivity with the hydroxyl group or carboxyl group of the base polymer and easy introduction of a crosslinked structure, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred.

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. As the isocyanate-based crosslinking agent, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; cyclopentyl diisocyanate, cyclohexyl diisocyanate, isophorone diisocyanate, etc. Alicyclic isocyanates; aromatic isocyanates such as 2,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane/phenylene diisocyanate Diisocyanate trimer adduct (for example, "Coronate L" manufactured by Tosoh), trimethylolpropane/hexamethylene diisocyanate adduct (for example, "Coronate HL" manufactured by Tosoh), Trimethylolpropane adduct of xylylene diisocyanate (for example, "Takenate D110N" manufactured by Mitsui Chemicals), trimeric isourate of hexamethylene diisocyanate (for example, "Coronate" manufactured by Tosoh) HX”) and other isocyanate adducts.

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 3 or more or 4 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-meta-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-di Glycidyl amino methyl) cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene two Alcohol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, three Hydroxymethyl propane polyglycidyl ether, diglycidyl adipate, diglycidyl phthalate, tris(2-hydroxyethyl) triglycidyl isocyanate, resorcinol diglycidyl Glyceryl ether, bisphenol-S-diglycidyl ether, etc. As the epoxy-based crosslinking agent, commercially available products such as "DENACOL" manufactured by Nagase chemteX and "Tetrad X" and "Tetrad C" manufactured by Mitsubishi Gas Chemical can also be used.

Even when the base polymer does not substantially contain nitrogen atoms, the crosslinking agent may contain nitrogen atoms. For example, an isocyanate crosslinking agent can be used to introduce a crosslinked structure into a base polymer that does not substantially contain nitrogen atoms. When the base polymer contains substantially no nitrogen atoms, by using crosslinking agents that do not contain nitrogen atoms such as epoxy-based crosslinking agents, there is an initial adhesion caused by the presence or absence of surface activation treatments such as plasma treatment The tendency of the difference to become smaller.

The amount of the crosslinking agent used may be appropriately adjusted according to the composition or molecular weight of the base polymer. The amount of the crosslinking agent used is about 0.01 to 10 parts by weight relative to 100 parts by weight of the base polymer, 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. In addition, the amount (parts by weight) of the crosslinking agent used relative to 100 parts by weight of the base polymer divided 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 , More preferably 0.003 to 0.055, particularly preferably 0.0045 to 0.044. By making the use amount of crosslinking agent larger than the ordinary acrylic optical transparent adhesive for permanent bonding, the adhesive has moderate hardness, and the paste residue on the adherend during secondary processing is reduced. , The tendency of secondary processing to improve.

(Crosslinking accelerator) The adhesive composition contains a crosslinking accelerator in addition to the crosslinking agent. By using a cross-linking accelerator, the cross-linking reaction (introduction of the cross-linked structure to the base polymer) can proceed efficiently. In addition, by using a cross-linking accelerator to introduce a cross-linked structure into the base polymer, there is a tendency for the adherend whose surface has been activated by the adhesive layer of the reinforcing film to exhibit lower initial adhesion.

As the crosslinking accelerator, organometallic compounds such as organometallic complexes (chelates), compounds of metals and alkoxy groups, and compounds of metals and alkoxy groups; and tertiary amines. In particular, from the viewpoint of suppressing the progress of the cross-linking reaction in a solution state at room temperature and ensuring the pot life of the adhesive composition, an organometallic compound is preferred. In addition, in terms of easily introducing a uniform crosslinking structure throughout the entire thickness direction of the adhesive layer, the crosslinking accelerator is preferably an organometallic compound that is liquid at room temperature.

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

Examples of iron-based crosslinking accelerators include tris(acetone) iron, tris(hexane-2,4-diketone) iron, tris(heptane-2,4-diketone) iron, tris(heptane) iron Alkane-3,5-dione)iron, tris(5-methylhexane-2,4-dione)iron, tris(octane-2,4-dione)iron, tris(6-methylheptane) Alkane-2,4-dione)iron, tris(2,6-dimethylheptane-3,5-dione)iron, tris(nonane-2,4-dione)iron, tris(nonane) -4,6-diketone) iron, tris(2,2,6,6-tetramethylheptane-3,5-dione) iron, tris(tridecane-6,8-dione) iron, Tris(1-phenylbutane-1,3-dione) iron, tris(hexafluoroacetone acetone) iron, tris(ethyl acetylacetate) iron, tris(n-propyl acetylacetate) iron, tris (Isopropyl Acetate) Iron, Tris(n-Butyl Acetate) Iron, Tris(Second Butyl Acetate) Iron, Tris(Tterbutyl Acetate) Iron, Tris(Acetyl Acetate) Methyl ester) iron, tris(ethyl acrylate) iron, tris(n-propyl propyl acetate) iron, tris(isopropyl propyl acetate) iron, tris(n-butyl propyl acetate) iron, tris( (2-butyl acrylate) iron, tris(tert-butyl acrylate) iron, tris(benzyl acetylacetate) iron, tris(dimethyl malonate) iron, tris(diethyl malonate) Ester) iron, iron trimethoxide, iron triethanol, iron triisopropoxide, etc.

Examples of tin-based crosslinking accelerators include: dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin maleate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, methoxide Tributyl tin, tributyl tin acetate, triethyl tin ethoxide, tributyl tin ethoxide, dioctyl tin oxide, dioctyl tin dilaurate, tributyl tin chloride, tributyl tin trichloroacetate, 2-ethylhexanoic acid Tin etc.

Examples of aluminum-based crosslinking accelerators include: aluminum diisopropoxide, aluminum diisopropoxide, aluminum dibutoxide, aluminum isopropoxide, aluminum ethoxide, ethyl acetate, aluminum diisopropoxide, and triacetate. Aluminum ethyl acetate, Alkyl Acetate Acetate Aluminum Diisopropoxide, Monoacetone Bis(Acetate Acetate) Aluminum, Triacetone Aluminum, etc.

As the zirconium-based crosslinking accelerator, zirconium tetraacetone acetonate, zirconium monoacetone acetonate, zirconium tributoxide monoacetone, zirconium naphthenate, zirconium propoxide, zirconium butoxide, etc. may be mentioned.

Examples of the zinc-based crosslinking accelerator include zinc naphthenate, zinc 2-ethylhexanoate, and the like.

As the titanium-based crosslinking accelerator, dibutyl titanium dichloride, tetrabutyl titanate, tetraisopropyl titanate, tetraoctyl titanate, titanium butoxide trichloride, titanium acetone, Titanium tetraacetylacetone, titanium ethyl acetate, titanium ammonium lactate, titanium triethanolamine, titanium diisopropanol diacetone, titanium isostearate, titanium diethanolamine, titanium ethylaminoethyl ethoxide Wait.

Examples of lead-based crosslinking accelerators include lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate.

Examples of cobalt-based crosslinking accelerators include cobalt 2-ethylhexanoate and cobalt benzoate.

The use amount of the crosslinking accelerator may be appropriately adjusted according to the type and amount of the crosslinking agent, and the type of crosslinking accelerator. The usage amount of the crosslinking accelerator is generally 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 used is preferably 0.01 to 2.0 parts by weight relative to 100 parts by weight of the base polymer. For the epoxy-based crosslinking agent, it is preferable to use a non-tin-based organic metal as the crosslinking accelerator. When a crosslinking accelerator is used for the isocyanate-based crosslinking agent, the amount of the crosslinking accelerator used is preferably 0.001 to 0.1 parts by weight.

The adhesive composition may also include a crosslinking retarder in addition to the crosslinking accelerator. By adding a crosslinking retarder, the progress of the crosslinking reaction in a solution state at room temperature can be inhibited, thereby prolonging the pot life of the adhesive composition. As the crosslinking retarder, β-ketoesters such as methyl acetylacetate, ethyl acetylacetate, octyl acetylacetate, oleyl acetylacetate, lauryl acetylacetate, and stearyl acetylacetate; Β-diketones such as acetone, 2,4-hexanedione, and benzylacetone; alcohols such as tertiary butanol. Among them, β-diketone is preferred, and acetone is particularly preferred. The amount of the crosslinking retarder used is about 0.1-30 parts by weight relative to 100 parts by weight of the total adhesive composition, preferably 25 parts by weight or less, and more preferably 20 parts by weight or less.

(Light Hardener) The adhesive composition constituting the adhesive layer 2 contains a light hardener in addition to the base polymer. If the adhesive layer 2 containing the photocurable adhesive composition is photocured after being bonded to the adherend, the adhesive force with the adherend is improved.

The light hardener has two or more polymerizable functional groups in one molecule. As the polymerizable functional group, those having polymerizability based on photoradical reaction are preferred, and as the light curing agent, a compound having two or more ethylenically unsaturated bonds in one molecule is preferred. In addition, the light hardener is preferably a compound exhibiting compatibility with the base polymer. In terms of exhibiting moderate compatibility with the base polymer, the light hardener is preferably one that is liquid at room temperature. By dissolving the light hardener and the base polymer and uniformly dispersing in the composition, the contact area with the adherend can be ensured, and the adhesive layer 2 with higher transparency can be formed. In addition, by making the base polymer and the light hardening agent have moderate compatibility, it is easy to uniformly introduce the cross-linked structure obtained by the light hardening agent into the adhesive layer 2 after light hardening, so as to exist and be adhered The tendency of the adhesion of the body to rise appropriately.

The compatibility of the base polymer and the light hardener is mainly affected by the structure of the compound. The structure and compatibility of the compound can be evaluated by, for example, the Hansen solubility parameter. The smaller the difference between the solubility parameter of the base polymer and the light hardener, the higher the compatibility.

In terms of high compatibility with the acrylic base polymer, it is preferable to use a polyfunctional (meth)acrylate as a light hardener. Examples of 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(methyl) ) Acrylate, di-trimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol poly(meth)acrylate, two Pentaerythritol hexa(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerol di(meth)acrylate, (meth)acrylate urethane, epoxy (meth)acrylate, Butadiene (meth)acrylate, isoprene (meth)acrylate, etc. Among them, in terms of excellent compatibility with acrylic base polymers, polyethylene glycol di(meth)acrylate or polypropylene glycol di(meth)acrylate is preferred, and poly(meth)acrylate is particularly preferred. Ethylene glycol di(meth)acrylate.

The compatibility of the base polymer and the light hardener is also affected by the molecular weight of the compound. There is a tendency that the lower 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 light hardener is preferably 1500 or less, more preferably 1000 or less, still more preferably 500 or less, and particularly preferably 400 or less.

From the viewpoint of high compatibility with the base polymer and improvement of the adhesive force after light curing, the functional group equivalent (g/eq) of the light curing agent is preferably 500 or less, more preferably 400 or less, and more Preferably it is 300 or less, particularly preferably 200 or less. On the other hand, if the functional group equivalent of the photocuring agent is too small, the crosslinking point density of the adhesive layer after photocuring may increase and the adhesiveness may decrease. Therefore, the functional group equivalent of the light hardener is preferably 80 or more, more preferably 100 or more, and still more preferably 130 or more.

In the combination of acrylic base polymer and multifunctional acrylate light hardening agent, when the functional group equivalent of the light hardening agent is small, the interaction between the base polymer and the light hardening agent is stronger, and the initial adhesive force increases , And cause the reduction of secondary processing. From the viewpoint of keeping the adhesive force between the adhesive layer 2 before photocuring and the adherend in an appropriate range, it is also preferable that the functional group equivalent of the photocuring agent is within the above range.

The content of the light hardener in the adhesive composition is preferably 10-50 parts by weight relative to 100 parts by weight of the base polymer. By setting the blending amount of the light curing agent within the above range, the adhesiveness of the adhesive layer after light curing and the adherend can be adjusted to an appropriate range. The content of the light hardener is more preferably 15 to 45 parts by weight, and still more preferably 20 to 40 parts by weight relative to 100 parts by weight of the base polymer.

(Photopolymerization initiator) The photopolymerization initiator is irradiated with active light to generate active species to promote the hardening reaction of the light hardener. As the photopolymerization initiator, a photocation initiator (photoacid generator), a photoradical initiator, a photoanion initiator (photobase generator), etc. can be used according to the kind of the photohardener or the like. When using an ethylenically unsaturated compound such as a polyfunctional acrylate as a light hardening agent, it is preferable to use a photo radical initiator as a polymerization initiator.

The photo-radical initiator generates free radicals by the irradiation of active light, and promotes the radical polymerization reaction of the photo-hardener by free radical transfer from the photo-radical initiator to the photohardener. As the photo-radical initiator (photo-radical generator), it is preferable to generate free radicals by irradiation of visible light or ultraviolet light with a wavelength shorter than 450 nm, and examples include hydroxy ketones and benzyl dimethyl ketals. Ketones, aminoketones, phosphine oxides, benzophenones, trichloromethyl-containing three 𠯤 derivatives, etc. The photo-radical initiator may be used alone or in combination of two or more kinds.

When transparency is required for the adhesive layer 2, the photopolymerization initiator is preferably less sensitive to light with a wavelength longer than 400 nm (visible light), for example, the absorbance coefficient at a wavelength of 405 nm can be used well 1×10 ² [mL g ^-1 cm ^-1 ] or less 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 still more preferably 0.03 to 2 parts by weight relative 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 still more preferably 0.1 to 5 parts by weight relative to 100 parts by weight of the light hardener.

(Other additives) In addition to the components exemplified above, the adhesive layer may also contain silane coupling agents, adhesiveness imparting agents, plasticizers, softeners, antioxidants, anti-deterioration agents, fillers, and coloring within the range that does not impair the characteristics of the present invention. Additives such as agents, ultraviolet absorbers, surfactants, and antistatic agents.

[Production of Reinforcing Film] The photocurable adhesive layer 2 is laminated on the film substrate 1 to obtain a reinforced film. The adhesive layer 2 can be directly formed on the film substrate 1, or an adhesive layer formed in a sheet form on another substrate can be transferred to the film substrate 1.

By applying the above-mentioned adhesive composition using roll coating, touch roll coating, gravure coating, reverse coating, roll brushing, spraying, dipping roll coating, bar coating, blade coating, gas Knife coating, curtain coating, lip coating, die nozzle coating, etc. are coated on the substrate, and the solvent is dried and removed as needed to form an adhesive layer. As the 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 still 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 still 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 adhesive layer 2 is, the more the adhesion with the adherend will increase. On the other hand, when the thickness of the adhesive layer 2 is too large, the fluidity before photocuring may be high, and handling may become difficult. Therefore, the thickness of the adhesive layer 2 is preferably 5-100 μm, more preferably 8-50 μm, still more preferably 10-40 μm, and particularly preferably 13-30 μm.

Preferably, the crosslinking is performed simultaneously with the drying of the solvent or by heating or aging after the drying of the solvent. The heating temperature or heating time is appropriately set according to the type of cross-linking agent or cross-linking accelerator used, and cross-linking is usually performed by heating in the range of 20°C to 160°C for about 1 minute to 7 days. The heating used to dry and remove the solvent can also serve as the heating for crosslinking.

The introduction of a cross-linked structure into the base polymer increases the gel fraction. The higher the gel fraction, the harder the adhesive, and when the reinforcing film is peeled from the adherend due to secondary processing, etc., the tendency of the paste to remain on the adherend can be suppressed. The gel fraction of the 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 adhesive layer 2 before light hardening can also be 70% or more or 75% or more.

Since the adhesive contains an unreacted light hardening agent, the gel fraction of the adhesive layer 2 before light hardening is generally below 90%. If the gel fraction of the adhesive layer 2 before photocuring is too large, the gripping force to the adherend may decrease, and the initial adhesive force may become insufficient. Therefore, the gel fraction of the adhesive layer 2 before photocuring is preferably 85% or less, and more preferably 80% or less.

The gel fraction can be determined as the insoluble matter in a solvent such as ethyl acetate. Specifically, as the insoluble matter after immersing the adhesive layer in ethyl acetate at 23°C for 7 days compared to the test before immersion The weight fraction of the sample (unit: weight %) is calculated. Generally speaking, the gel fraction of a polymer is equal to the degree of crosslinking. The more crosslinked parts in the polymer, the greater the gel fraction. Therefore, the more the amount of crosslinking agent used (the content of crosslinkable functional groups), the greater the gel fraction tends to be. In addition, by using a crosslinking accelerator, the amount of unreacted functional groups of the crosslinking agent is reduced, so there is a tendency for the gel fraction to increase. In the 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 by the crosslinking agent, the light hardener also maintains an unreacted state. Therefore, a photo-curable adhesive layer 2 containing a base polymer and a photo-curing agent is formed. When the adhesive layer 2 is formed on the film substrate 1, it is preferable to attach a spacer 5 to the adhesive layer 2 for the purpose of protecting the adhesive layer 2 or the like. The adhesive layer 2 can also be cross-linked after the spacer 5 is attached.

In the case of forming the adhesive layer 2 on another substrate, a reinforcing film is obtained by transferring the adhesive layer 2 to the film substrate 1 after drying the solvent. The base material used in the formation of the adhesive layer can also be directly used as the spacer 5.

As the separator 5, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films can be suitably used. The thickness of the spacer is usually 3 to 200 μm, preferably about 10 to 100 μm. Preferably, the contact surface between the spacer 5 and the adhesive layer 2 is implemented by a silicone-based, fluorine-based, long-chain alkyl-based, or fatty amide-based mold release agent, or silica powder, etc. The demoulding treatment. By performing a mold release treatment on the surface of the separator 5, when the film base material 1 and the separator 5 are peeled off, it can be maintained at the interface between the adhesive layer 2 and the separator 5 to be peeled and fixed on the film base material 1. The state of the adhesive layer 2.

[Use of Reinforcing Film] The reinforcing film of the present invention is used by sticking to the device or device constituent parts. The adherend to which the reinforcing film is attached is not particularly limited, and various electronic devices, optical devices, and their constituent parts can be cited. The reinforcing film can be attached to the entire surface of the adherend, or can be selectively attached only to the part that needs reinforcement. In addition, after the reinforcing film is attached to the entire surface of the adherend, the reinforcing film at the part that does not need to be reinforced can be cut, and the reinforcing film can be peeled off. As long as it is before the adhesive is photocured, the reinforcing film is temporarily stuck to the surface of the adherend, so the reinforcing film can be easily peeled off from the surface of the adherend.

Since appropriate rigidity is imparted by laminating the reinforcing film, the improvement in operability and the effect of preventing damage can be expected. In the manufacturing steps of the device, when the reinforcing film is attached to the semi-finished product, the reinforcing film can be attached to the semi-finished product that is larger than the size of the product before being cut. The reinforcing film can also be attached to the mother roll of the device manufactured by the roll to roll process in a roll to roll.

＜Characteristics of the adhesive layer before light curing＞ In the reinforcing film 10, the adhesive layer 2 is fixed to the film base material 1, and after being bonded to the adherend and before light curing, the adhesive force to the adherend is small. Therefore, before photocuring, the reinforcing film can be easily peeled from the adherend, and the secondary workability is excellent. In addition, processing such as cutting the reinforcing film and removing the reinforcing film on a part of the surface of the adherend before photocuring can also be easily performed.

(Adhesion) From the viewpoint of making it easy to peel from the adherend and preventing the paste remaining on the adherend after peeling off the reinforcing film, the adhesive force between the adhesive layer 2 and the adherend before photocuring is preferably 1.5 N/ 25 mm or less, more preferably 1 N/25 mm or less, still more preferably 0.7 N/25 mm or less, and particularly preferably 0.5 N/25 mm or less. The adhesive force between the adhesive layer 2 and the adherend before light hardening can also 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 reinforcing film during storage or handling, the adhesive force between the 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 , And more preferably 0.02 N/25 mm or more, particularly preferably 0.03 N/25 mm or more.

The reinforcing film preferably has an adhesive force to the polyimide film in the state before the adhesive layer is photocured within the above range. In flexible display panels, flexible printed wiring boards (FPC), devices that integrate display panels and wiring boards, etc., flexible substrate materials are used. From the viewpoint of heat resistance or dimensional stability, Polyimide films are generally used. The adhesive layer has the above-mentioned adhesive force to the polyimide film as the substrate, and the reinforcing film is easily peeled off before the adhesive is photocured, and the adhesion reliability after photocuring is excellent.

It is also possible to activate the adherends such as the polyimide film on the surface of the device for the purpose of cleaning before attaching the reinforcing film. Examples of surface activation treatment include plasma treatment, corona treatment, glow discharge treatment, and the like. Especially in terms of processing under atmospheric pressure and high activation effect, atmospheric pressure slurry processing is preferable.

If the surface activation treatment is performed on the adherend, the adhesion between the adhesive layer 2 before photocuring and the adherend tends to be higher than when the surface activation treatment is not performed. If the adhesive force between the adhesive layer and the adherend before photocuring is too large, secondary processing may become difficult. Therefore, the adhesive force between the surface-activated adherend and the adhesive layer before photocuring is preferably 2 N/25 mm or less, more preferably 1.5 N/25 mm or less, and more preferably 1 N/25 mm below. The adhesive force between the surface-activated adherend and the adhesive layer before photocuring can also be 0.7 N/25 mm or less or 0.5 N/25 mm or less. The adhesive force between the surface-activated adherend and the adhesive layer before photocuring is preferably less than 4 times the adhesive force of the adherend without surface activation and the adhesive layer before photocuring, more preferably It is 3 times or less. The adhesive force between the surface-activated adherend and the adhesive layer before photocuring can also be less than 2 times or 1.7 times the adhesive force of the adherend without surface activation and the adhesive layer before photocuring Or less than 1.5 times.

The surface of the adherend that has undergone activation treatment contains a large number of active groups such as hydroxyl, carbonyl, and carboxyl groups, and the adhesive force is easily increased due to the intermolecular interaction with the polar functional groups of the base polymer. Especially when the base polymer contains a nitrogen atom, it is believed that the unpaired electron of the nitrogen atom has a strong interaction with the active group of the adherend that has undergone activation treatment, so the adhesive force is likely to increase. Especially when the adherend is polyimide, it is believed that by activation treatment, the amide acid, the terminal amine group or the carboxyl group (or carboxylic anhydride group) will be activated, and the polar functional group of the base polymer The interaction is stronger, which is also related to the increase in initial adhesion.

By using crosslinking accelerators such as organometallics, there is a tendency that the increase in initial adhesion caused by the surface activation treatment of the adherend is suppressed, especially the crosslinking function contained in 1 molecule of the crosslinking agent This tendency is greater when the number of groups is large and the density of functional groups is high. If a crosslinking accelerator is used, the crosslinkable functional group will be activated and the reactivity will increase. Therefore, the number of unreacted functional groups is reduced, and the number of polymer chains cross-linked by one cross-linking agent is large, and it is easy to form a high-density cross-linked structure, which is believed to be related to the suppression of the increase in initial adhesion.

For example, it is believed that when the cross-linking density is low, in the main part of the adhesive layer, the light hardener (multifunctional monomer) is likely to exist in the gaps between the polymer chains. In contrast, the cross-linking density is higher. When it is high, since the gap between the polymer chains is small (smaller), the light hardening agent is not easy to exist in the main body part. In the adhesive layer before light hardening, the light hardening agent is likely to be concentrated in the vicinity of the interface. Therefore, it is believed that even in the case of surface activation treatment on the adherend, since the interaction between the adherend and the base polymer at the interface is small, the initial increase in adhesive force will be suppressed.

In addition, since the degree of crosslinking (gel fraction) can be increased by using a crosslinking accelerator, unreacted (uncrosslinked) hydroxyl groups or carboxyl groups are reduced. It is believed that the cross-linked structure part is easy to be embedded in the polymer, and the oxygen atoms of the hydroxyl or carboxyl group that react with the cross-linking agent are less exposed on the surface, which also helps to suppress the initial adhesion increase. Especially when the number of polymer chains cross-linked by one cross-linking agent is large, it is considered that because the cross-linked structure part is less exposed on the surface, the polar groups of the base polymer and the adherend are active The interaction of the base is small, and the initial increase in adhesion is suppressed.

(Storage modulus) The adhesive layer 2 preferably has a shear storage modulus G′ _i at 25° C. before photocuring of 1×10 ⁴ to 1.2×10 ⁵ Pa. Shear storage modulus (hereinafter, only described as "storage modulus") is based on the method described in JIS K7244-1 "Plastics-Test Methods for Dynamic Mechanical Properties" at a frequency of 1 Hz at- The range of 50 to 150°C is calculated as the value at a specific temperature when the temperature rise rate is 5°C/min.

In a substance that exhibits viscoelasticity like an adhesive, the storage modulus G'is used as an indicator of the degree of hardness. The storage modulus of the adhesive layer has a higher correlation with the cohesive force. The higher the cohesive force of the adhesive, the greater the gripping force of the adherend. As long as the storage modulus of the adhesive layer 2 before light hardening is 1×10 ⁴ Pa or more, the adhesive has sufficient hardness and cohesive power, so it is not easy to produce on the adherend when the reinforcing film is peeled from the adherend Paste remains. In addition, when the storage modulus of the adhesive layer 2 is large, the adhesive can be prevented from overflowing from the end surface of the reinforcing film. As long as the storage modulus of the adhesive layer 2 before light hardening is 1.2×10 ⁵ Pa or less, it will be easy to peel off at the interface between the adhesive layer 2 and the adherend, and it is not easy to produce adhesion during secondary processing. The agglomeration of the agent layer is broken or the paste remains on the surface of the adherend.

Secondary processing to improve the reinforcing of film to suppress the residual paste in view of the adhesion of the body in terms of secondary processing, storage under the adhesive layer of the front light 25 2 deg.] C and cured modulus G _'i better It is 3×10 ⁴ to 1×10 ⁵ Pa, more preferably 4×10 ⁴ to 9.5×10 ⁴ Pa.

＜Light hardening of adhesive layer＞ After bonding the reinforcing film to the adherend, the adhesive layer 2 is irradiated with active light to light-harden the adhesive layer. Examples of active rays include ultraviolet rays, visible rays, infrared rays, X-rays, α rays, β rays, and γ rays. In terms of being able to suppress the hardening of the adhesive layer in the storage state and being easy to harden, the active light is preferably ultraviolet light. The irradiation intensity or irradiation time of the active light can be appropriately set according to the composition or thickness of the adhesive layer. The active light irradiation of the adhesive layer 2 can be carried out from either side of the film substrate 1 side and the adherend side, or active light irradiation can be carried out from both sides.

＜Characteristics of the adhesive layer after light curing＞ (Adhesion) From the viewpoint of the bonding reliability of the device in practical use, the bonding force between the adhesive layer 2 and the adherend after light curing is preferably 2 N/25 mm or more, more preferably 3 N/25 mm or more, and then Preferably it is 5 N/25 mm or more. The adhesive force between the reinforcing film and the adherend after light curing of the adhesive layer can also be 6 N/25 mm or more, 8 N/25 mm or more, 10 N/25 mm or more, 12 N/25 mm or more, or 13 N/25 mm or more. The reinforcing film is preferably the adhesive layer after photocuring that has an adhesive force in the above range to the polyimide film. The adhesive force between the adhesive layer 2 and the adherend after light curing is preferably at least 5 times the adhesive force of the adhesive layer 2 and the adherend before light curing, more preferably at least 8 times, and more preferably 10 Times more. The adhesive force between the adhesive layer and the adherend after light curing can also be 20 times or more, 30 times or more, 40 times or more, or 50 times the adhesive force of the adhesive layer and the adherend before light curing.

As described above, there is a tendency that an adhesive including a base polymer with a cross-linked structure introduced using a cross-linking agent and a cross-linking accelerator suppresses the increase in the initial adhesive force caused by the surface activation treatment of the adherend. On the other hand, when the surface activation treatment is performed on the adherend, there is an adhesive force between the adhesive layer 2 and the adherend after photocuring compared with the case where the surface activation treatment of the adherend is not performed The tendency to become bigger. That is, when using a reinforcing film with an adhesive layer with a specific composition, by performing surface activation treatment such as plasma treatment on the adherend, the increase in initial adhesion is suppressed, and the secondary workability is ensured. After light curing, a higher adhesive force will be realized, and a device with excellent adhesive reliability of the reinforcing film can be obtained. Especially in the case of using an organometallic crosslinking accelerator, there is a tendency that the initial increase in adhesive strength is suppressed when the adherend is subjected to surface activation treatment, and the increase in adhesive strength after photocuring becomes more pronounced.

(Storage modulus) The adhesive layer 2 preferably has a storage modulus G′ _f at 25° C. after light curing of 1.0×10 ⁵ Pa or more. As long as the storage modulus of the adhesive layer 2 after light curing is 1.0×10 ⁵ Pa or more, the adhesion force with the adherend increases as the cohesive force increases, and higher bonding reliability can be obtained. On the other hand, when the storage modulus is too large, the adhesive is difficult to wet and expand, and the contact area with the adherend becomes smaller. In addition, the stress dispersibility of the adhesive is reduced, so there is a tendency for the peeling force to easily propagate to the bonding interface and the adhesive force with the adherend to decrease. Therefore, the storage modulus G′ _f at 25° C. of the adhesive layer 2 after light curing is preferably 2×10 ⁶ Pa or less. To improve the reinforcing layer after the adhesive was light cured film in terms of the reliability point of view and then, G _'f is more preferably ^{1.1 × 10 5 ~ 1.2 × 10} 6 Pa, and further preferably 1.2 × 10 ⁵ ~ 1 × 10 ⁶ Pa.

The ratio of the storage modulus _G'f /G' _i at 25° C. before and after light curing of the adhesive layer 2 is preferably 2 or more. As long as the G 'is _F G' _i of 2 times or more, by increasing the photohardenable of G 'becomes larger, secondary processability can be both before and after photohardening of the photohardenable Next reliability. _G'f /G' _i is more preferably 4 or more, still more preferably 8 or more, and particularly preferably 10 or more. G _'f / G' of the upper limit of _i is not particularly limited, to G _'f / G' of the case when _i is too large, easily lead to the front of the photo-curing by G 'is small and the initial cause of the failure and then, after the photohardening or because The G'is too large and the reliability of the connection is reduced. 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 autoclave treatment for the purpose of enhancing the affinity of the laminate interface of a plurality of laminate members, or heat treatment such as thermocompression bonding for bonding circuit members. When performing such heat treatment, it is preferable that the adhesive between the reinforcing film and the adherend does not flow from the end surface.

From the viewpoint of suppressing the overflow of the adhesive during high-temperature heating, the storage modulus at 100°C of the adhesive layer 2 after photohardening is preferably 5×10 ⁴ Pa or more, more preferably 8×10 ⁴ Pa or more , And more preferably 1×10 ⁵ Pa or more. From the viewpoints of preventing the overflow of the adhesive during heating and preventing the decrease of the adhesive force during heating, the storage modulus at 100°C of the adhesive layer 2 after photohardening is preferably that of the storage modulus at 50°C 60% or more, more preferably 65% or more, still more preferably 70% or more, and particularly preferably 75% or more.

By laminating the reinforcing film, moderate rigidity can be given to the semi-finished product as the adherend, and the stress can be relieved and dispersed. Therefore, various defects that may occur in the manufacturing step can be suppressed, production efficiency can be improved, and yield can be improved. In addition, since the reinforcing film is easily peeled from the adherend before the adhesive layer is photocured even when the adherend has been subjected to surface activation treatment, it is also easy to laminate or cause poor adhesion. Easy secondary processing. After light-curing the adhesive layer, it exhibits a high adhesive force to the adherend, the reinforcing film is not easy to peel off the surface of the device, and the bonding reliability is excellent. [Example]

Examples are listed below for further description, but the present invention is not limited to these examples.

[Comparative Example 1] ＜polymerization of basic polymer＞ Put 95 parts by weight of butyl acrylate (BA) as monomers and 5 parts by weight of acrylic acid (AA) as monomers into a reaction vessel equipped with a thermometer, agitator, reflux condenser and nitrogen introduction tube, and azobis as a thermal polymerization initiator. 0.2 parts by weight of isobutyronitrile (AIBN) and 233 parts by weight of ethyl acetate as a solvent were blown with nitrogen gas, and nitrogen replacement was performed for about 1 hour while stirring. Thereafter, it was heated to 60°C and reacted for 7 hours to obtain a solution of acrylic polymer with a weight average molecular weight of 600,000.

＜Preparation of adhesive composition＞ Add 0.5 parts by weight of a 4-functional epoxy compound ("Tetrad C" manufactured by Mitsubishi Gas Chemical) as a crosslinking agent to a solution of acrylic polymer, and a multifunctional acrylic monomer manufactured by Shinnakamura 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 photopolymerization initiator ("Irgacure 651" manufactured by BASF) 0.1 parts by weight to prepare an adhesive composition.

＜Coating and crosslinking of adhesive composition＞ The adhesive composition was coated on a polyethylene terephthalate film with a thickness of 75 μm (“Lumirror S10” manufactured by Toray) without surface treatment so that the thickness after drying became 25 μm using a grooved roller. Dry at 130°C for 1 minute to remove the solvent. After that, paste the separator (25 μm thick polyethylene terephthalate film with silicone release treatment on the surface) on the coated surface of the adhesive. The demoulding surface. Thereafter, an aging treatment was carried out for 4 days in an environment of 25° C., and cross-linking was performed to obtain a reinforcing film with a photocurable adhesive sheet fixed on the film substrate and a separator temporarily adhered thereon.

[Examples 1 to 5] In the preparation of the adhesive composition, in addition to the crosslinking agent, multifunctional acrylic monomer, and photopolymerization initiator, the type and amount of organic metal crosslinking shown in Table 1 are added to the acrylic polymer solution Accelerator. Except for adding an organometallic crosslinking accelerator, a reinforcing film was produced in the same manner as in Comparative Example 1.

[Example 6] In Example 6, in the preparation of the adhesive composition, in addition to the crosslinking agent, the organometallic crosslinking accelerator, the multifunctional acrylic monomer, and the photopolymerization initiator, the acrylic polymer solution was added containing Carboxy acrylic oligomer ("ARUFON UC-3000" manufactured by Toagosei; weight average molecular weight: 10,000; glass transition temperature: 65°C; acid value: 74 mgKOH/g) 1 part by weight. Except for this, a reinforcing film was produced in the same manner as in Example 4.

[Measurement of the adhesion of polyimide film] ＜Adhesive force before light hardening＞ A polyimide film with a thickness of 12.5 μm ("Kapton 50EN" manufactured by DU PONT-TORAY) is attached to a glass plate via a double-sided tape ("No.531" manufactured by Nitto Denko) to obtain a polyimide for measurement Film substrate. The separator was peeled off from the surface of the reinforcing film with a width of 25 mm × a length of 100 mm, and was attached to the polyimide film substrate for measurement using a hand roller to prepare a sample for adhesion measurement (no plasma treatment) .

While conveying the polyimide substrate for measurement at a conveying speed of 3 m/min, the surface of the polyimide film was subjected to plasma treatment using an atmospheric-pressure plasma processor at an electrode voltage of 160 V. The reinforcing film was attached to the polyimide film substrate for measurement after the plasma treatment using a hand roller to prepare a sample for adhesion measurement (with plasma treatment).

Using these test samples, the end of the polyethylene terephthalate film of the reinforced film was held by a chuck, and the 180° peel test of the reinforced film was performed at a tensile speed of 300 mm/min, and the peel strength was measured. Based on the obtained results, the ratio of the adhesive force when plasma treatment is applied to the adhesive force when there is no plasma treatment (the increase rate of adhesive force caused by plasma treatment) is calculated.

<Adhesive force after light curing> A reinforcing film is attached to the polyimide film substrate (with plasma treatment and without plasma treatment), and then a 365 nm LED (Light Emitting Diode) is used ) The light source irradiates ultraviolet rays with a cumulative light quantity of 4000 mJ/cm ² from the side of the reinforcing film (the side of the PET film) to light-harden the adhesive layer. Using this test sample, the adhesive force was measured by a 180° peel test in the same manner as described above.

The composition of the adhesive of the reinforcing film of Comparative Example 1 and Examples 1 to 6 (oligomer, multifunctional monomer, photopolymerization initiator, crosslinking agent and crosslinking accelerator type, and relative to the basic polymerization 100 parts by weight of the substance), the adhesion to the polyimide film and the increase rate of the adhesion caused by the plasma treatment (the adhesion of "plasma treatment" is relative to the adhesion of "no plasma treatment" The ratio) and the adhesive force after photohardening are shown in Table 1.

In Table 1 and Table 2, "UC3000" is "ARUFON UC-3000" manufactured by Toa Synthetic, "A200" is "NK Ester A200" manufactured by Shinnakamura Chemical Industry, and "APG700" is "ARUFON UC-3000" manufactured by Shinnakamura Chemical Industry. "NK Ester APG700", "Irg651" is "Irgacure 651" manufactured by BASF, and "Irg184" is "Irgacure 184" manufactured by BASF. The details of the crosslinking accelerators in Table 1 and Table 2 are as follows. Fe: tris(acetone) iron ("acetone iron(III)" manufactured by Japan Chemical Industry) Zr: Zirconium tetraacetone (manufactured by Tokyo Chemical Industry) Ti: Titanium diisopropoxy bisacetylacetonate (manufactured by Tokyo Chemical Industry) Al: Aluminum triacetone (manufactured by Tokyo Chemical Industry) Sn: Dioctyltin dilaurate ("Embilizer OL-1" manufactured by Tokyo Fine Chemical)

[Table 1] Oligomer Multifunctional monomer Photopolymerization initiator Crosslinking agent Crosslinking accelerator Before light hardening After light hardening Adhesion (N/25 mm) Adhesion force rise rate (times) Adhesion (N/25 mm) species the amount No plasma With plasma No plasma With plasma Comparative example 1 A200 30 parts by weight Irg651 0.1 parts by weight Tetrad C 0.5 parts by weight - 0.15 0.21 1.40 7.4 18.2 Example 1 Zr 0.2 0.16 0.17 1.03 12.7 23.0 Example 2 Zr 0.15 0.15 0.15 1.05 10.1 21.4 Example 3 Ti 1.0 0.09 0.13 1.38 12.8 21.3 Example 4 Fe 0.025 0.11 0.12 1.05 9.0 19.0 Example 5 Al 0.1 0.10 0.12 1.11 9.1 18.0 Example 6 UC3000 1 part by weight Fe 0.025 0.11 0.13 1.11 10.5 22.9

In any one of Comparative Example 1 and Examples 1 to 6, the initial adhesion to the polyimide film substrate that has not undergone plasma treatment is less than 0.2 N/25 mm, which can be self-polyimide film Peel easily. In addition, when light curing of the adhesive is performed, the adhesive force increases, and the adhesive is firmly bonded to the polyimide film substrate.

In Comparative Example 1 where no crosslinking accelerator was added, the initial adhesion to the polyimide film substrate after plasma treatment exceeded 0.2 N/25 mm, and it increased to that of the polyimide film without plasma treatment The initial adhesion of the substrate is 1.4 times.

In Examples 1 to 5 with the addition of a crosslinking accelerator, compared with Comparative Example 1, the initial adhesion to the polyimide film substrate after plasma treatment was lower, and the initial adhesion caused by the plasma treatment was lower The rise is suppressed. In Example 6 where acrylic oligomer was added in addition to the acrylic base polymer, similar to Example 4 using the same iron-based crosslinking accelerator, the initial adhesive force caused by the plasma treatment was The rise is suppressed.

If focusing on the adhesive force after photocuring of the adhesive, in any embodiment, the polyimide substrate after the plasma treatment is bonded to the reinforcing film and photocured, and the case where the plasma treatment is not performed Compared with the time, the adhesive force increased, and the adhesive force was higher than that of Comparative Example 1.

According to the above results, it can be seen that by using a crosslinking agent and a crosslinking accelerator to introduce a crosslinked structure into the base polymer, the initial adhesion to the adherend that has undergone activation treatment such as plasma treatment is low, and secondary processing It has excellent properties, and after photocuring the adhesive, it can achieve higher adhesion than when no crosslinking accelerator is used, and has excellent adhesion reliability.

[Comparative Example 2] ＜polymerization of basic polymer＞ Add 63 parts by weight of 2-ethylhexyl acrylate (2EHA), 9 parts by weight of methyl methacrylate (MMA), and acrylic hydroxyl as monomers into a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen introduction tube. 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, and pass Nitrogen replacement was performed for about 1 hour while stirring. Thereafter, it was heated to 60°C and reacted for 7 hours to obtain a solution of acrylic polymer with a weight average molecular weight of 1.2 million.

＜Preparation of adhesive composition＞ Add a 75% ethyl acetate solution of trimethylolpropane adduct of xylylene diisocyanate as a crosslinking agent to the acrylic polymer solution ("Takenate D110N" manufactured by Mitsui Chemicals) based on the solid content 2.5 parts by weight, as a multifunctional acrylic monomer, "NK Ester APG700" (polypropylene glycol #700 (n=12) diacrylate; molecular weight 808, functional group equivalent 404 g/eq) 30 weight Part, and 1 part by weight of a photopolymerization initiator ("Irgacure 184" manufactured by BASF) to prepare an adhesive composition.

＜Coating and crosslinking of adhesive composition＞ The adhesive composition was applied, heated and dried, and crosslinked in the same manner as in Comparative Example 1, to produce a reinforcing film with a photocurable adhesive sheet and a spacer temporarily adhered on the film substrate. .

[Example 7 and Example 8] In the preparation of the adhesive composition, in addition to the crosslinking agent, multifunctional acrylic monomer, and photopolymerization initiator, the type and amount of organic metal crosslinking shown in Table 2 are added to the acrylic polymer solution Accelerator. Except for adding an organometallic crosslinking accelerator, a reinforcing film was produced in the same manner as in Comparative Example 2.

[Example 9] In the preparation of the adhesive composition, "Irgacure 651" manufactured by BASF was used instead of "Irgacure 184" manufactured by BASF as the photopolymerization initiator. Except for this, a reinforcing film was produced in the same manner as in Example 7.

[Example 10] In the preparation of the adhesive composition, 20 parts by weight of "NK Ester A200" manufactured by Shinnakamura Chemical Industry Co., Ltd. was added instead of 30 parts by weight of "NK Ester APG700" manufactured by Shinnakamura Chemical Industry Co., Ltd. as a multifunctional acrylic monomer. Except for this, a reinforcing film was produced in the same manner as in Example 7.

[Measurement of the adhesion of polyimide film] Laminate the reinforcing film on each of the polyimide film substrate that has not undergone plasma treatment and the polyimide film substrate after plasma treatment. For each of the adhesive layer before and after photocuring, The adhesion force was measured by a peel test.

The composition of the adhesive of the reinforcing film of Comparative Example 2 and Examples 7-10, the adhesive force to the polyimide film, the increase rate of the adhesive force caused by plasma treatment, and the adhesive force after photocuring are shown in Table 2.

[Table 2] Multifunctional monomer Photopolymerization initiator Crosslinking agent Crosslinking accelerator Before light hardening After light hardening Adhesion (N/25 mm) Adhesion force rise rate (times) Adhesion (N/25 mm) species the amount species the amount species the amount No plasma With plasma No plasma With plasma Comparative example 2 APG700 30 Irg184 0.1 Takenate D110N 2.5 parts by weight - 0.50 2.07 4.14 9.7 16.9 Example 7 APG700 30 Irg184 0.1 Fe 0.005 0.30 0.61 2.03 4.4 10.4 Example 8 APG700 30 Irg184 0.1 Sn 0.03 0.39 0.93 2.36 6.3 12.5 Example 9 APG700 30 Irg651 0.1 Fe 0.005 0.44 1.05 2.40 7.7 14.1 Example 10 A200 20 Irg184 0.1 Fe 0.005 0.19 0.45 2.33 11.6 27.6

In Comparative Example 2 where no crosslinking accelerator is added, the initial adhesion to the polyimide film substrate after plasma treatment exceeds 2 N/25 mm, and it rises to the level of the polyimide film that has not undergone plasma treatment. The initial adhesive force of the substrate is more than 4 times, and it becomes difficult to peel the reinforcing film from the polyimide film substrate.

In Examples 7 and 8 with the addition of a crosslinking accelerator, the initial adhesion to the polyimide film substrate after plasma treatment was 1 N/25 mm or less. Compared with Comparative Example 2, the initial adhesion increased Repressed. In Example 9 in which the type of photopolymerization initiator was changed, and in Example 10 in which the type of polyfunctional monomer was changed, it was also the same as in Example 7 in which the same iron-based crosslinking accelerator was used. The increase of initial adhesive force caused by plasma treatment is suppressed.

According to the results of Comparative Example 1 and Examples 1 to 6 shown in Table 1 (an example in which a crosslinked structure is introduced into a copolymer of butyl acrylate and acrylic acid by an epoxy-based crosslinking agent), and the results shown in Table 2 Shown in Comparative Example 2 and Examples 7 to 10 (in the copolymer of 2-ethylhexyl acrylate, methyl methacrylate, hydroxyethyl acrylate, and N-vinylpyrrolidone by isocyanate The result of the example where the linking agent is introduced with a cross-linking structure), it can be seen that regardless of the type of base polymer or cross-linking agent, by using a cross-linking accelerator in addition to the cross-linking agent, The initial adhesive force will be suppressed low.

1: Film substrate 2: Adhesive layer 5: spacer 10: Reinforcing film 20: adherend

Fig. 1 is a cross-sectional view showing the laminated structure of the reinforcing film. Fig. 2 is a cross-sectional view showing the laminated structure of the reinforcing film. Fig. 3 is a cross-sectional view showing a device for sticking and installing a reinforcing film.

1: Film substrate

2: Adhesive layer

10: Reinforcing film

Claims (16)

A reinforcing film comprising a film substrate and an adhesive layer fixedly laminated on one of the main surfaces of the film substrate; The adhesive layer includes a photocurable composition, and the photocurable composition includes a base polymer having a crosslinked structure, a photocuring agent, and a photopolymerization initiator; and The base polymer having a cross-linked structure is formed by the cross-linking reaction of a composition comprising a base polymer, a cross-linking agent, and a cross-linking accelerator. The reinforcing film of claim 1, wherein the crosslinking accelerator is an organometallic compound. The reinforced film of claim 1 or 2, wherein the base polymer contains one or more selected from the group consisting of a hydroxyl-containing monomer and a carboxyl-containing monomer as a monomer unit, and is bonded by a hydroxyl group or a carboxyl group The cross-linking agent is introduced with a cross-linked structure. The reinforced film according to any one of claims 1 to 3, wherein the crosslinking agent is an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent. The reinforcing film according to any one of claims 1 to 4, wherein the gel fraction of the photocurable composition is 60% or more. The reinforcing film according to any one of claims 1 to 5, which contains an acrylic polymer as the base polymer. The reinforced film according to any one of claims 1 to 6, wherein the photocurable composition contains 10 to 50 parts by weight of the light curing agent relative to 100 parts by weight of the base polymer. The reinforcing film according to any one of claims 1 to 7, wherein the light hardener is a multifunctional (meth)acrylate. The reinforcing film according to any one of claims 1 to 8, wherein the functional group equivalent of the light hardener is 100 to 500 g/eq. The reinforcing film according to any one of claims 1 to 9, wherein the adhesive force with the polyimide film before photocuring the adhesive layer is 1 N/25 mm or less. A method for manufacturing a reinforcing film, which is the method for manufacturing a reinforcing film according to any one of claims 1 to 10, In this method, a composition comprising a base polymer, a crosslinking agent, a crosslinking accelerator, a light hardening agent, and a photopolymerization initiator is layered on a film substrate, and the base polymer is combined with the above The reaction of the cross-linking agent introduces a cross-linked structure into the above-mentioned base polymer to form an adhesive layer. A method for manufacturing a reinforcing film, which is the method for manufacturing a reinforcing film according to any one of claims 1 to 10, This method is to coat a composition comprising a base polymer, a crosslinking agent, a crosslinking accelerator, a light hardener, and a photopolymerization initiator in layers, and the base polymer and the crosslinking agent are reacted Introducing a cross-linked structure into the above-mentioned base polymer to form an adhesive layer; and The above-mentioned adhesive layer is transferred to the film substrate. A method of manufacturing a device, the device is attached with a reinforcing film on the surface, The method is to temporarily stick the above-mentioned adhesive layer of the reinforcing film of any one of claims 1 to 10 on the surface of the adherend, and then, By irradiating the adhesive layer with active light, the adhesive layer is photocured, and the adhesive force between the reinforcing film and the adherend is increased. The method for manufacturing a device according to claim 13, wherein the surface activation treatment of the adherend is performed before temporarily adhering the reinforcing film. The device manufacturing method of claim 14, wherein the surface activation treatment is plasma treatment. A reinforcement method, which is a reinforcement method of attaching a reinforcement film to the surface of the adherend, The method is to temporarily stick the above-mentioned adhesive layer of the reinforcing film of any one of claims 1 to 10 on the surface of the adherend after the activation treatment after the surface activation treatment of the adherend, and By irradiating the adhesive layer with active light, the adhesive layer is photocured, and the adhesive force between the reinforcing film and the adherend is increased.

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