JP6581704B1 - Reinforcement film - Google Patents

Abstract

[PROBLEMS] To easily rework immediately after bonding to an adherend, to be firmly bonded to the adherend, and after bonding to the adherend, it is possible to arbitrarily set the time until the adhesive force is improved. Provide configurable reinforcing film. A reinforcing film (10) includes an adhesive layer (2) fixedly laminated on one main surface of a film substrate (1). An adhesive layer consists of a photocurable composition containing a base polymer, a photocuring agent, and a photoinitiator. The wetting speed of the reinforcing film to the glass plate is 0.3 cm 2 / sec to 4 cm 2 / sec. [Selection] Figure 1

Description

  The present invention relates to a reinforcing film to be stuck on a device surface.

  An adhesive film may be attached to the surface of an optical device such as a display or an electronic device for the purpose of surface protection or impact resistance. In such an adhesive film, an adhesive layer is usually fixedly laminated on the main surface of the film substrate, and the adhesive film is bonded to the device surface via the adhesive layer.

  In a state before use such as assembly, processing, and transportation of a device, the adherence film can be temporarily attached to the surface of the device or device component, thereby suppressing damage and damage to the adherend. Such an adhesive film is a process material and is peeled off before use of the device. As described in Patent Document 1, the adhesive film used as a process material is easy to spread on the adherend, and can be easily peeled off from the adherend with low adhesiveness. It is required that no adhesive residue occurs.

  Patent Document 2 discloses a pressure-sensitive adhesive film that is used while being attached to a device surface in addition to device assembly, processing, transportation, and the like. Such an adhesive film has a function of reinforcing the device by dispersing the impact to the device and imparting rigidity to the flexible device in addition to the surface protection.

  When the adhesive film is bonded to the adherend, bonding failure such as mixing of bubbles or displacement of the bonding position may occur. When a bonding failure occurs, an adhesive film is peeled from the adherend and another adhesive film is bonded (rework). Since the adhesive film used as the process material is designed on the premise of peeling from the adherend, rework is easy. On the other hand, in general, the reinforcing film is not supposed to be peeled off from the device, and is firmly adhered to the surface of the device, so that rework is difficult.

  Patent Document 3 discloses a pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) designed to have low adhesiveness immediately after being bonded to an adherend and to increase the adhesive force over time. The pressure-sensitive adhesive film in which such a pressure-sensitive adhesive layer is fixed and laminated on the film base is easy to peel off from the adherend immediately after being bonded to the adherend, and after a predetermined time has elapsed, Since it adheres firmly, it can be used as a reinforcing film having reworkability.

JP 2013-107998 A JP 2017-132777 A WO2015 / 163115 pamphlet

  Adhesive film to be bonded to the device surface is required to be easy to peel and remove (rework) in the case of poor bonding as well as excellent workability of bonding due to the difficulty of mixing bubbles during bonding. It is done. The reinforcing film whose adhesive force with the adherend changes with time can be easily reworked immediately after being bonded, but is not sufficiently flexible with respect to the lead time of the process. For example, a reinforcing film including a pressure-sensitive adhesive layer whose adhesive strength increases with time is subjected to inspection and rework of the bonded state within a predetermined time until the adhesive strength increases after being bonded to an adherend. There is a need. In addition, when a reinforcing film is bonded to the entire surface of a device or device component and then the reinforcing film is removed from a part of the region, it is necessary to perform the processing until the adhesive force increases. is there.

  In view of the above, the present invention is excellent in adhesion with an adherend, and can be arbitrarily set a time until adhesion is improved after bonding with the adherend, and by improving adhesion An object is to provide a reinforcing film that can be firmly bonded to an adherend.

  The reinforcing film of the present invention includes an adhesive layer fixedly laminated on one main surface of a film substrate. An adhesive layer consists of a photocurable composition containing a base polymer, a photocuring agent, and a photoinitiator. As the base polymer of the pressure-sensitive adhesive layer, for example, an acrylic polymer is used.

  It is preferable that a crosslinked structure is introduced into the base polymer. For example, the base polymer contains a hydroxy group-containing monomer and / or a carboxy group-containing monomer as a monomer unit, and a crosslinking structure such as a polyfunctional isocyanate compound or a polyfunctional epoxy compound is bonded to these functional groups to form a crosslinked structure. Is introduced.

  The photocuring agent is a monomer or oligomer having two or more polymerizable functional groups, and polyfunctional (meth) acrylate or the like is used. The molecular weight of the photocuring agent is preferably 1500 or less. The functional group equivalent of the photocuring agent is preferably about 100 to 500 g / eq. As for the quantity of the photocuring agent in the photocurable composition which comprises an adhesive layer, 10-50 weight part is preferable with respect to 100 weight part of base polymers.

Reinforcing film is preferably wetting rate relative to the glass plate is 0.3 cm ² / sec ~4cm ² / sec. The reinforcing film before photocuring the pressure-sensitive adhesive layer preferably has an adhesive strength to an adherend such as a glass plate of 0.03 N / 25 mm or more and less than 1 N / 25 mm. The reinforcing film after photocuring the pressure-sensitive adhesive layer preferably has an adhesive force of 1 N / 25 mm or more to an adherend such as a glass plate.

  In the reinforcing film of the present invention, the pressure-sensitive adhesive layer is made of a photocurable composition, and the pressure-sensitive adhesive layer is photocured after adhesion to the adherend, thereby increasing the adhesive force with the adherend. Rework is easy because the adhesive strength with the adherend is small before photocuring. Moreover, since it has a moderate wetting speed with respect to adherends, such as glass, it is excellent in bonding workability | operativity. Since the pressure-sensitive adhesive after photocuring exhibits a high adhesive force, the device can be reinforced and the reliability can be improved by bonding the reinforcing film. Since the photocurable pressure-sensitive adhesive can arbitrarily set the timing of curing after being bonded to the adherend, the reinforcing film of the present invention can flexibly cope with the lead time of the process.

It is sectional drawing which shows the laminated structure of a reinforcement film. It is sectional drawing which shows the laminated structure of a reinforcement film. It is sectional drawing which shows the device with which the reinforcement film was stuck.

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

  FIG. 2 is a cross-sectional view of a reinforcing film in which a separator 5 is temporarily attached on the main surface of the pressure-sensitive adhesive layer 2. FIG. 3 is a cross-sectional view showing a state in which the reinforcing film 10 is stuck on the surface of the device 20.

  The separator 5 is peeled and removed from the surface of the pressure-sensitive adhesive layer 2, and the exposed surface of the pressure-sensitive adhesive layer 2 is bonded to the surface of the device 20 as an adherend, whereby the reinforcing film 10 is bonded to the surface of the device 20. . In this state, the pressure-sensitive adhesive layer 2 is before photocuring, and the reinforcing film 10 (pressure-sensitive adhesive layer 2) is temporarily attached on the device 20. By photocuring the pressure-sensitive adhesive layer 2, the adhesive force at the interface between the device 20 and the pressure-sensitive adhesive layer 2 is increased, and the device 20 and the reinforcing film 10 are fixed.

  “Fixed” refers to a state in which two laminated layers are firmly bonded and peeling at the interface between them is impossible or difficult. “Temporary attachment” is a state in which the adhesive force between two laminated layers is small and can be easily peeled off at the interface between the two layers.

  In the reinforcing film shown in FIG. 2, the film base 1 and the pressure-sensitive adhesive layer 2 are fixed, and the separator 5 is temporarily attached to the pressure-sensitive adhesive layer 2. 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 state where the pressure-sensitive adhesive layer 2 is fixed on the film base material 1 is maintained. No adhesive remains on the separator 5 after peeling.

  In the device on which the reinforcing film 10 shown in FIG. 3 is pasted, the device 20 and the pressure-sensitive adhesive layer 2 are temporarily attached before the pressure-sensitive adhesive layer 2 is photocured. When the film substrate 1 and the device 20 are peeled off, peeling occurs at the interface between the pressure-sensitive adhesive layer 2 and the device 20, and the state where the pressure-sensitive adhesive layer 2 is fixed on the film base material 1 is maintained. Since no adhesive remains on the device 20, rework is easy. Since the adhesive force between the pressure-sensitive adhesive layer 2 and the device 20 increases after photocuring the pressure-sensitive adhesive layer 2, it is difficult to peel off the film substrate 1 from the device 20. Cohesive failure may occur.

[Film substrate]
As the film substrate 1, a plastic film is used. 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 with the pressure-sensitive adhesive layer 2 is not subjected to release treatment.

The thickness of the film substrate is, for example, about 4 to 500 μm. From the viewpoint of reinforcing the device by imparting rigidity or impact relaxation, 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 imparting flexibility to the reinforcing film and improving handling properties, the thickness of the film substrate 1 is preferably 300 μm or less, and more preferably 200 μm or less. From the viewpoint of achieving both flexibility and mechanical strength, compressive strength of the film substrate 1 is preferably 100~3000kg / cm ^2, more preferably ^{200~2900kg / cm 2, 300~2800kg / cm} 2 and more 400 to 2700 kg / cm ² is particularly preferable.

  Examples of the plastic material constituting the film substrate 1 include polyester resins, polyolefin resins, cyclic polyolefin resins, polyamide resins, polyimide resins, polyether ether ketone, and polyether sulfone. In a reinforcing film for an optical device such as a display, the film substrate 1 is preferably a transparent film. Moreover, when irradiating actinic light from the film base material 1 side and performing photocuring of the adhesive layer 2, the film base material 1 may have transparency with respect to the actinic light used for hardening of the adhesive layer 2. preferable. Polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferably used because they have both mechanical strength and transparency. When irradiating actinic rays from the adherend side, the adherend need only have transparency to actinic rays, and the film substrate 1 may not be transparent to actinic rays.

  The surface of the film substrate 1 may be provided with a functional coating such as an easy adhesion layer, an easy slip layer, a release layer, an antistatic layer, a hard coat layer, and an antireflection layer. In addition, in order to adhere the film base material 1 and the adhesive layer 2 as mentioned above, it is preferable that the release layer is not provided in the surface with the adhesive layer 2 of the film base material 1 provided.

[Adhesive layer]
The pressure-sensitive adhesive layer 2 fixedly laminated on the film substrate 1 is made of a photocurable composition containing a base polymer, a photocuring agent and a photopolymerization initiator. Since the adhesive layer 2 has a low adhesive force with an adherend such as a device or a device component before photocuring, rework is easy. Since the adhesive layer 2 is improved in adhesive strength with the adherend by photocuring, the reinforcing film is not easily peeled off from the device surface even when the device is used, and has excellent adhesion reliability.

  The photocurable pressure-sensitive adhesive hardly cures in a general storage environment, and is cured by irradiation with actinic rays such as ultraviolet rays. Therefore, the reinforcing film of the present invention has an advantage that the timing of curing the pressure-sensitive adhesive layer 2 can be arbitrarily set, and can flexibly cope with the lead time of the process.

<Wetting speed>
Wetting rate is preferably more than 0.3 cm ² / s for glass reinforcing film, more preferably at least 0.35 cm ² / sec, 0.4 cm more preferably more than ² / s, particularly preferably at least 0.45 cm ² / sec . The larger the wetting speed, the easier the adhesive spreads when the reinforcing film is bonded to the adherend, and the mixing workability is improved because air bubbles and foreign matter are prevented from entering the bonding interface. . Considering the workability at the time of bonding to the adherend, the higher the wetting speed, the better. On the other hand, a pressure-sensitive adhesive layer (photocurable composition) having a high wetting rate is liable to cause poor appearance due to bleeding out of the photocuring agent. In addition, the pressure-sensitive adhesive layer with a high wetting rate has a liquid surface and may have poor initial adhesion to an adherend such as glass, and the composition is poorly compatible. Even if it goes, adhesiveness may not rise sufficiently. Therefore, wetting rate for the glass of the reinforcement film is preferably 4 cm ² / sec or less, 3.5 cm, more preferably less than ² / sec, more preferably 3 cm ² / sec or less, particularly preferably 2.5 cm ² / sec.

<Adhesive strength>
From the viewpoint of facilitating peeling from the adherend during reworking and preventing adhesive residue on the adherend after peeling off the reinforcing film, the reinforcing film before the photocuring of the pressure-sensitive adhesive layer 2 is applied to the glass plate. The adhesive force is preferably less than 1 N / 25 mm, more preferably 0.8 N / 25 mm or less, further preferably 0.7 N / 25 mm or less, and particularly preferably 0.6 N / 25 mm or less. From the viewpoint of preventing the peeling of the reinforcing sheet from the adherend during storage and handling, the adhesive strength of the reinforcing film to the glass plate is preferably 0.03 N / 25 mm or more, more preferably 0.05 N / 25 mm or more, 0.1 N / 25 mm or more is further preferable, and 0.2 N / 25 mm or more is particularly preferable.

  From the standpoint of device reliability during practical use, the adhesive strength of the reinforcing film after photocuring the pressure-sensitive adhesive layer 2 is preferably 1 N / 25 mm or more, more preferably 2 N / 25 mm or more, and 3 N / 25 mm or more. Is more preferable. The adhesive strength of the pressure-sensitive adhesive layer 2 after photocuring is preferably 2 times or more, more preferably 3 times or more, and further preferably 5 times or more of the adhesive strength of the pressure-sensitive adhesive layer 2 before photocuring.

<Thickness>
The thickness of the pressure-sensitive adhesive layer 2 is, for example, about 1 to 300 μm. There exists a tendency for adhesiveness with a to-be-adhered body to improve, so that the thickness of the adhesive layer 2 is large. On the other hand, when the thickness of the pressure-sensitive adhesive layer 2 is excessively large, the fluidity before photocuring is high and handling may be difficult. Therefore, the thickness of the pressure-sensitive adhesive layer 2 is preferably 5 to 100 μm, more preferably 8 to 50 μm, further preferably 10 to 40 μm, and particularly preferably 13 to 30 μm.

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

<Composition>
The pressure-sensitive adhesive layer 2 is a photocurable composition containing a base polymer, a photocuring agent and a photopolymerization initiator. From the viewpoint of setting the adhesiveness and wetting rate of the pressure-sensitive adhesive layer 2 before photocuring to an appropriate range, it is preferable that a crosslinked structure is introduced into the base polymer.

(Base polymer)
The base polymer is the main component of the pressure-sensitive adhesive composition. The type of the base polymer is not particularly limited, and an acrylic polymer, a silicone polymer, a urethane polymer, a rubber polymer, or the like may be appropriately selected. In particular, the pressure-sensitive adhesive composition preferably contains an acrylic polymer as the base polymer because it is excellent in optical transparency and adhesiveness, and the adhesiveness is easily controlled. % Or more is preferably an acrylic polymer.

  As the acrylic polymer, a polymer containing a (meth) acrylic acid alkyl ester as a main monomer component is preferably used. In the present specification, “(meth) acryl” means acryl and / or methacryl.

  As the (meth) acrylic acid alkyl ester, a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is suitably used. The alkyl group of the (meth) acrylic acid alkyl ester may be linear or branched. Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, ( T-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2- (meth) acrylic acid 2- Ethylhexyl, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate , Dodecyl (meth) acrylate, isotridodecyl (meth) acrylate Tetradecyl (meth) acrylate, isotetradecyl (meth) acrylate, pentadecyl (meth) acrylate, cetyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, iso (meth) acrylate Examples include octadecyl, nonadecyl (meth) acrylate, aralkyl (meth) acrylate, and the like.

  The content of the (meth) acrylic acid alkyl ester is preferably 40% by weight or more, more preferably 50% by weight or more, and still more preferably 55% by weight or more based on 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. Examples of the monomer having a crosslinkable functional group include a hydroxy group-containing monomer and a carboxy group-containing monomer. The acrylic base polymer may have both a hydroxyl group-containing monomer and a carboxy group-containing monomer as monomer components, or may have only one of them. The hydroxy group and carboxy group of the base polymer serve as a reaction point with a crosslinking agent described later. For example, when an isocyanate-based crosslinking agent is used, it is preferable to contain a hydroxy group-containing monomer as a copolymer component of the base polymer. When using an epoxy-based crosslinking agent, it is preferable to contain a carboxy group-containing monomer as a copolymer component of the base polymer. 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 on the adherend during reworking tends to be reduced.

  Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, (meth) Examples include 8-hydroxyoctyl acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, 4- (hydroxymethyl) cyclohexyl) methyl (meth) acrylate, and the like. Examples of the carboxy group-containing monomer include (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate carboxypentyl, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

  In the acrylic base polymer, the total amount of the hydroxy group-containing monomer and the carboxy group-containing monomer relative to the total amount of the constituent monomer components is preferably 1 to 30% by weight, more preferably 3 to 25% by weight, More preferably, it is 20% by weight.

  Acrylic base polymers include N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinyl oxazole, vinyl morpholine, N-acryloyl morpholine as constituent monomer components. Nitrogen-containing monomers such as N-vinylcarboxylic acid amides and N-vinylcaprolactam may be contained.

  The acrylic base polymer may contain monomer components other than those described above. Acrylic base polymer contains, for example, cyano group-containing monomer, vinyl ester monomer, aromatic vinyl monomer, epoxy group-containing monomer, vinyl ether monomer, sulfo group-containing monomer, phosphate group-containing monomer, acid anhydride group-containing monomer component A monomer or the like may be contained.

  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. When a crosslinked structure is introduced into the base polymer, the molecular weight of the base polymer refers to the molecular weight before introducing the crosslinked structure.

  There exists a tendency for an adhesive to become hard, so that there is much content of the high Tg monomer component in the structural component of a base polymer. The high Tg monomer means a monomer having a high glass transition temperature (Tg) of the homopolymer. Monomers having a homopolymer Tg of 40 ° C. or higher include dicyclopentanyl methacrylate (Tg: 175 ° C.), dicyclopentanyl acrylate (Tg: 120 ° C.), isobornyl methacrylate (Tg: 173 ° C.), (Meth) acrylic monomers such as nyl acrylate (Tg: 97 ° C), methyl methacrylate (Tg: 105 ° C), 1-adamantyl methacrylate (Tg: 250 ° C), 1-adamantyl acrylate (Tg: 153 ° C); acryloylmorpholine (Tg: 145 ° C), dimethylacrylamide (Tg: 119 ° C), diethylacrylamide (Tg: 81 ° C), dimethylaminopropylacrylamide (Tg: 134 ° C), isopropylacrylamide (Tg: 134 ° C), hydroxyethylacrylamide ( g: 98 ° C.) amide group-containing vinyl monomers such as; methacrylate (Tg: 228 ℃), acrylic acid (Tg: 106 ℃) acids such monomers; N- vinylpyrrolidone (Tg: 54 ℃), and the like.

  In the acrylic base polymer, the content of the monomer having a Tg of 40 ° C. or higher is preferably 1 to 50% by weight, more preferably 3 to 40% by weight, based on the total amount of the constituent monomer components. . In order to form an adhesive layer having an appropriate hardness and excellent reworkability, it is preferable that the monomer component of the base polymer includes a monomer component having a Tg of 80 ° C. or higher as the homopolymer Tg. More preferably, it contains a monomer component at 100 ° C. or higher. In the acrylic base polymer, the content of the monomer having a Tg of 100 ° C. or more with respect to the total amount of the constituent monomer components is preferably 0.1% by weight or more, and more preferably 0.5% by weight or more. It is more preferably 1% by weight or more, and particularly preferably 3% by weight or more.

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

(Crosslinking agent)
From the viewpoint of giving the adhesive an appropriate cohesive force, it is preferable that a crosslinked structure is introduced into the base polymer. For example, a cross-linking structure is introduced by adding a cross-linking agent to the solution after polymerizing the base polymer and heating as necessary. Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a carbodiimide crosslinking agent, and a metal chelate crosslinking agent. These crosslinking agents react with functional groups such as hydroxy groups and carboxy groups introduced into the base polymer to form a crosslinked structure. An isocyanate-based crosslinking agent and an epoxy-based crosslinking agent are preferred because they are highly reactive with the hydroxy group and carboxy group of the base polymer and can easily introduce a crosslinked structure.

  As the isocyanate-based crosslinking agent, polyisocyanate having two or more isocyanate groups in one molecule is used. Examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; 2,4-tolylene diene. Aromatic isocyanates such as isocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane / tolylene diisocyanate trimer adduct (for example, “Coronate L” manufactured by Tosoh), trimethylolpropane / hexamethylene Diisocyanate trimer adduct (for example, “Coronate HL” manufactured by Tosoh), trimethylolpropane adduct of xylylene diisocyanate (for example, manufactured by Mitsui Chemicals) Takenate D110N ", isocyanurate of hexamethylene diisocyanate (e.g., manufactured by Tosoh" Coronate HX ") isocyanate adducts of the like.

  As the epoxy-based crosslinking agent, a polyfunctional epoxy compound having two or more epoxy groups in one molecule is used. The epoxy group of the epoxy crosslinking agent may be a glycidyl group. Examples of the epoxy-based crosslinking agent include N, N, N ′, N′-tetraglycidyl-m-xylenediamine, 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 diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, penta Erythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl Ether, adipic acid diglycidyl ester, o- phthalic acid diglycidyl ester, triglycidyl - tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol -S- diglycidyl ether, and the like. Commercially available products such as “Denacol” manufactured by Nagase ChemteX and “Tetrad X” and “Tetrad C” manufactured by Mitsubishi Gas Chemical may be used as the epoxy crosslinking agent.

  What is necessary is just to adjust the usage-amount of a crosslinking agent suitably according to a composition, molecular weight, etc. of a base polymer. The amount of the crosslinking agent used is about 0.01 to 10 parts by weight, preferably 0.1 to 7 parts by weight, more preferably 0.2 to 6 parts by weight, and still more preferably 100 parts by weight of the base polymer. 0.3 to 5 parts by weight. Further, the value obtained by dividing the amount (parts by weight) of the crosslinking agent used relative 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, preferably 0.001 to 0 0.077 is more preferable, 0.003 to 0.055 is more preferable, and 0.0045 to 0.044 is particularly preferable. Glue to the adherend during rework by increasing the amount of crosslinking agent used to make the adhesive moderately harder than general acrylic optical adhesives for permanent adhesion. There is a tendency that the rest is reduced and the reworkability is improved.

  A crosslinking catalyst may be used to promote the formation of a crosslinked structure. For example, as a crosslinking catalyst for an isocyanate-based crosslinking agent, a metal-based crosslinking catalyst (particularly a tin-based crosslinking catalyst) such as tetra-n-butyl titanate, tetraisopropyl titanate, ferric nasem, butyltin oxide, dioctyltin dilaurate, and dibutyltin dilaurate. Etc. The amount of the crosslinking catalyst used is generally 0.05 parts by weight or less with respect to 100 parts by weight of the base polymer.

(Photocuring agent)
The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer 2 contains a photocuring agent in addition to the base polymer. When the pressure-sensitive adhesive layer 2 made of the photocurable pressure-sensitive adhesive composition is subjected to photocuring after being bonded to the adherend, the adhesive force with the adherend is improved.

  As the photocuring agent, a photocurable monomer or photocurable oligomer having two or more polymerizable functional groups in one molecule is used. The photocuring agent is preferably a compound having an ethylenically unsaturated bond such as a vinyl group or a (meth) acryloyl group as a polymerizable functional group. Moreover, the photocuring agent is preferably a compound showing compatibility with the base polymer. In view of moderate compatibility with the base polymer, the photocuring agent is preferably liquid at room temperature. When the photocuring agent is appropriately compatible with the base polymer and is uniformly dispersed in the composition, the wetting rate can be within an appropriate range.

  The compatibility between the base polymer and the photocuring agent is mainly influenced by the structure of the compound. The structure and compatibility of the compound can be evaluated by, for example, the Hansen solubility parameter, and the compatibility tends to increase as the difference in the solubility parameter between the base polymer and the photocuring agent decreases.

  Since the compatibility with the acrylic base polymer is high, it is preferable to use a polyfunctional (meth) acrylate as a photocuring agent. Polyfunctional (meth) acrylates include polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, bisphenol A ethylene oxide modified di (meth) acrylate, bisphenol A propylene oxide Modified di (meth) acrylate, alkanediol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, ethoxylated isocyanuric acid tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol di ( (Meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, ethoxylated pentaerythritol La (meth) acrylate, pentaerythrole tetra (meth) acrylate, dipentaerystol poly (meth) acrylate, dipentaerythrole hexa (meth) acrylate, neopentyl glycol di (meth) acrylate, glycerin di (meth) acrylate , Urethane (meth) acrylate, epoxy (meth) acrylate, butadiene (meth) acrylate, isoprene (meth) acrylate, and the like.

  The compatibility between the base polymer and the photocuring agent also depends on the molecular weight of the compound. The smaller the molecular weight of the photocurable compound, the higher the compatibility with the base polymer. In light of compatibility with the base polymer, the molecular weight of the photocuring agent is preferably 1500 or less, and more preferably 1000 or less.

  The type and content of the photocuring agent affect the adhesive strength after photocuring. The smaller the functional group equivalent (that is, the greater the number of functional groups per unit molecular weight) and the greater the content of the photocuring agent, the greater the adhesive force after photocuring. From the viewpoint of increasing the adhesive strength after photocuring, the functional group equivalent (g / eq) of the photocuring agent is preferably 500 or less, and more preferably 450 or less. On the other hand, when the photocrosslinking density is excessively increased, the viscosity of the pressure-sensitive adhesive is decreased, and the adhesive force may be decreased. Therefore, the functional group equivalent of the photocuring agent is preferably 100 or more, more preferably 130 or more, and even more preferably 150 or more.

  In the combination of acrylic base polymer and polyfunctional 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 adhesive strength of the adhesive before photocuring (Initial adhesive force) tends to increase. In the application of the present invention, an excessive increase in the initial adhesive force may lead to a decrease in reworkability. Also from the viewpoint of maintaining the adhesive force between the pressure-sensitive adhesive layer 2 before photocuring and the adherend within an appropriate range, the functional group equivalent of the photocuring agent is preferably within the above range.

  10-50 weight part is preferable with respect to 100 weight part of base polymers, as for content of the photocuring agent in an adhesive composition, 13-40 weight part is more preferable, and 15-40 weight part is further more preferable. The photocurable pressure-sensitive adhesive layer 2 is obtained by including the photocurable compound as an uncured monomer or oligomer in the pressure-sensitive adhesive composition. In order to include the photocuring agent in the composition in an uncured state, it is preferable to add the photocuring agent to the polymer solution obtained by polymerizing the base polymer.

  If the base polymer of the adhesive layer and the photo-curing agent are not completely compatible, the liquid photo-curing agent is localized near the surface of the adhesive layer (adhesive interface with the adherend) and the weak boundary layer ( Weak Boundary Layer (WBL) is easily formed. When WBL in which a photocuring agent is localized is formed, the surface of the pressure-sensitive adhesive layer has a strong liquid property, so that the wetting speed increases and the workability of bonding to an adherend tends to improve. .

  An adhesive having a highly crosslinked base polymer and a high gel fraction generally has a dominant elastic behavior and tends to have low wettability to an adherend. On the other hand, when the WBL is formed, the surface (adhesion interface) characteristics change while maintaining the bulk characteristics of the pressure-sensitive adhesive layer. That is, when the WBL is formed, the viscosity of the surface is increased while maintaining the “hardness” of the pressure-sensitive adhesive as a bulk property, so that the wetting speed at the time of bonding is improved and the rework is performed. There exists a tendency for peeling with an adherend to become easy.

  When the compatibility between the base polymer and the photo-curing agent is too low, the photo-curing agent tends to bleed out on the surface of the pressure-sensitive adhesive layer, WBL with strong liquid properties is formed on the surface of the pressure-sensitive adhesive layer, and the wetting rate is greatly increased. To rise. Therefore, although the workability of bonding is improved, the bleed-out photocuring agent may cause poor appearance and contamination of the adherend. In addition, when the photocuring agent bleeds out to form a liquid WBL, the initial adhesive force may be insufficient because it is difficult to maintain the step. When the compatibility between the photocuring agent and the base polymer is low, even if the pressure-sensitive adhesive is photocured, the adhesive properties as a bulk are hardly increased, and the adhesion reliability of the reinforcing film may be inferior.

As described above, in the photocurable pressure-sensitive adhesive containing the base polymer and the photocuring agent, the wetting speed is an index of the bonding workability and also the compatibility index of the base polymer and the photocuring agent. When the wetting speed is low, the bonding workability is low, and bonding defects such as mixing of bubbles and entrapment of foreign matters are likely to occur. On the other hand, when the wetting rate is excessively high, the photocuring agent bleeds out and poor adhesion tends to occur. Therefore, as described above, wetting rate is preferably 0.3~4cm ² / sec, more preferably 0.35~3.5cm ² / sec, more preferably 0.4~3cm ² / sec, 0.45 ~2.5cm ² / sec is particularly preferable.

  The wetting rate can be adjusted to the above range by adjusting the content of the photocuring agent, controlling the compatibility between the base polymer and the photocuring agent, or the like. As the content of the photocuring agent in the photocurable pressure-sensitive adhesive composition increases, the wetting rate tends to increase. In addition, the lower the compatibility between the base polymer and the photocuring agent, the higher the wetting rate. As described above, the compatibility between the base polymer and the photocuring agent can be adjusted by the similarity of both chemical structures (solubility parameter), the molecular weight of the photocuring agent, the functional group equivalent, and the like.

  When the photocuring agent has a similar chemical structure, the higher the functional group equivalent (the higher the molecular weight of the molecular chain connecting the polymerizable functional groups), the lower the compatibility with the base polymer and the lower the wetting rate. Tend. For example, when the photocuring agent is polyethylene glycol diacrylate, the wetting rate tends to increase as the number of repeating units of ethylene oxide (EO) increases. From the viewpoint of adjusting the wetting rate within the above range, the number of repeating units of EO is preferably about 2 to 8, more preferably about 3 to 7.

(Photopolymerization initiator)
The photopolymerization initiator generates active species upon 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 photoanion initiator (photobase generator), or the like is used depending on the type of the photocuring agent. When an ethylenically unsaturated compound such as a polyfunctional acrylate is used as the photocuring agent, it is preferable to use a photoradical initiator as the polymerization initiator.

  The photoradical initiator generates radicals upon irradiation with actinic rays, and promotes radical polymerization reaction of the photocuring agent by radical transfer from the photoradical initiator to the photocuring agent. As the photo radical initiator (photo radical generator), those that generate radicals by irradiation with visible light or ultraviolet light having a wavelength shorter than 450 nm are preferable. Hydroxy ketones, benzyl dimethyl ketals, amino ketones, acylphosphine Examples thereof include oxides, benzophenones, and trichloromethyl group-containing triazine derivatives. A radical photoinitiator may be used independently and may be used in mixture of 2 or more types.

When transparency is required for the pressure-sensitive adhesive layer 2, the photopolymerization initiator preferably has a low sensitivity to light having a wavelength longer than 400 nm (visible light). For example, the extinction coefficient at a wavelength of 405 nm is 1 × 10 ² [ mLg ^-1 cm ^-1] photoinitiator or less are preferably used.

  The content of the photopolymerization initiator in the pressure-sensitive adhesive layer 2 is preferably 0.01 to 5 parts by weight, more preferably 0.02 to 3 parts by weight, and 0.03 to 2 parts by weight with respect to 100 parts by weight of the base polymer. Part is more preferred. As for content of the photoinitiator in the adhesive layer 2, 0.02-10 weight part is preferable with respect to 100 weight part of photocuring agents, 0.05-7 weight part is more preferable, 0.1-5 Part by weight is more preferred.

(Other additives)
In addition to the components exemplified above, the adhesive layer contains a silane coupling agent, tackifier, plasticizer, softener, deterioration inhibitor, filler, colorant, ultraviolet absorber, antioxidant, and surface activity. An additive such as an agent and an antistatic agent may be contained within a range not impairing the characteristics of the present invention.

[Production of reinforcing film]
A laminated film is obtained by laminating the photocurable pressure-sensitive adhesive layer 2 on the film substrate 1. The pressure-sensitive adhesive layer 2 may be directly formed on the film substrate 1, or a pressure-sensitive adhesive layer formed in a sheet shape on another substrate may be transferred onto the film substrate 1.

  Apply the above adhesive composition by roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coat, etc. The pressure-sensitive adhesive layer is formed by coating on a substrate and removing the solvent by drying as necessary. As a drying method, an appropriate method can be adopted as appropriate. The heat 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.

  When the pressure-sensitive adhesive composition contains a cross-linking agent, it is preferable to advance the cross-linking by heating or aging simultaneously with the drying of the solvent or after the drying of the solvent. The heating temperature and heating time are appropriately set depending on the type of the crosslinking agent to be used, and are usually crosslinked by heating in the range of 20 ° C. to 160 ° C. for about 1 minute to 7 days. The heating for removing the solvent by drying 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, the harder the pressure-sensitive adhesive, and the adhesive residue on the adherend tends to be suppressed when the reinforcing film is peeled off from the adherend by rework or the like. The gel fraction before photocuring of the pressure-sensitive adhesive layer 2 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 pressure-sensitive adhesive layer 2 may be 70% or more or 75% or more. If the gel fraction before photocuring of the pressure-sensitive adhesive layer 2 is excessively large, the anchoring force on the adherend may be reduced, and the initial adhesive force may be insufficient. Therefore, the gel fraction of the pressure-sensitive adhesive layer 2 before photocuring is preferably 95% or less, more preferably 90% or less, still more preferably 85% or less, and particularly preferably 80% or less. The gel fraction can be determined as an insoluble content in a solvent such as ethyl acetate. Specifically, the insoluble component after the pressure-sensitive adhesive layer is immersed in ethyl acetate at 23 ° C. for 7 days is measured with respect to the sample before the immersion. It is calculated | required as a weight fraction (unit: weight%). In general, the gel fraction of the polymer is equal to the degree of cross-linking, and the more cross-linked portions in the polymer, the greater the gel fraction.

  Even after the crosslinking structure is introduced into the polymer by the crosslinking agent, the photocuring agent remains in an unreacted state. Therefore, the photocurable pressure-sensitive adhesive layer 2 including the base polymer and the photocuring agent is formed. When the pressure-sensitive adhesive layer 2 is formed on the film substrate 1, it is preferable to attach a separator 5 on the pressure-sensitive adhesive layer 2 for the purpose of protecting the pressure-sensitive adhesive layer 2 or the like. Crosslinking may be performed after the separator 5 is provided on the pressure-sensitive adhesive layer 2.

  When the pressure-sensitive adhesive layer 2 is formed on another substrate, the reinforcing film is obtained by transferring the pressure-sensitive adhesive layer 2 onto the film substrate 1 after drying the solvent. The base material used for forming 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, or a polyester film is 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 subjected to a release treatment such as a silicone-based, fluorine-based, long-chain alkyl-based, or fatty acid amide-based release agent, or silica powder. preferable. When the surface of the separator 5 is subjected to the mold release treatment, when the film base 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 pressure-sensitive adhesive is formed on the film base 1. The state in which the layer 2 is fixed is maintained.

[Use of reinforcing film]
The reinforcing film is used by being attached to an adherend such as a device or a device component. By bonding the reinforcing film, moderate rigidity is imparted to the adherend, and therefore, an improvement in handling properties and an effect of preventing breakage are expected. Since the reinforcing film of the present invention has a higher wetting speed than a general pressure-sensitive adhesive sheet for permanent adhesion, it is possible to suppress the entrainment of bubbles and foreign matters when the reinforcing film is bonded to the adherend, and the bonding is performed. Excellent workability. Further, since the reinforcing film has an appropriate wetting speed and initial adhesive force, it can suppress peeling from the adherend during storage and handling.

  In the device manufacturing process, when the reinforcing film is bonded to the work-in-process, the reinforcing film may be bonded to the large work-in-process before being cut into the product size. A reinforcing film may be bonded to a mother roll of a device manufactured by a roll-to-roll process using a roll-to-roll.

  The adherend to which the reinforcing film is bonded is not particularly limited, and examples thereof include various electronic devices, optical devices, and component parts thereof. As devices are highly integrated, reduced in size and weight, and reduced in thickness, the thickness of members constituting the device tends to decrease. The thinning of the constituent members tends to cause bending and curling due to stress and the like at the lamination interface. Further, the thinning tends to cause bending due to its own weight. By bonding the reinforcing film, rigidity can be imparted to the adherend, so that bending, curling, bending, and the like due to stress, dead weight, and the like are suppressed, and handling properties are improved. Therefore, by sticking the reinforcing film to the work-in-process in the device manufacturing process, it is possible to prevent defects and defects during conveyance and processing by an automated apparatus.

  In automatic conveyance, it is inevitable that the work in process to be conveyed contacts the conveyance arm or pin. In addition, the work in process may be cut to adjust the shape or remove unnecessary portions. Highly integrated, small, light, and thin devices are likely to be damaged due to local stress concentration during contact with a conveying device or cutting. In the manufacturing process of a device in which a plurality of members are stacked, not only the members are sequentially stacked, but some of the members, process materials, and the like may be peeled off from the work in process. In the case where the member is thinned, stress may be locally concentrated at the peeling site and the vicinity thereof, resulting in breakage or dimensional change. Since the reinforcing film 10 has the stress dispersibility due to the pressure-sensitive adhesive layer 2, the reinforcing film 10 is bonded to the object to be transported and the object to be processed, so that appropriate rigidity is given and stress is relieved. Dispersed, it is possible to suppress problems such as cracks, cracks, peeling, and dimensional changes.

  The reinforcing film 10 may be bonded to the entire surface of the adherend 20 or may be selectively bonded only to a portion that requires reinforcement. Moreover, after bonding a reinforcement film on the whole surface of a to-be-adhered body, the reinforcement film of the location which does not require reinforcement | strengthening may be cut | disconnected, and it may peel and remove from the surface of a to-be-adhered body. Since the reinforcing film is temporarily attached to the surface of the adherend before the process for increasing the adhesive strength of the pressure-sensitive adhesive layer 2, the reinforcing film 10 can be easily peeled and removed from the surface of the adherend 20.

<Characteristics of pressure-sensitive adhesive layer before photocuring>
(Adhesive strength)
As described above, from the viewpoint of showing appropriate adhesion to the adherend, and that it is easy to peel off from the adherend during rework and prevents adhesive residue on the adherend after peeling the reinforcing film. The adhesive strength of the pressure-sensitive adhesive layer 2 before photocuring to the glass plate is preferably 0.03 N / 25 mm or more and less than 1 N / 25 mm, more preferably 0.05 to 0.8 N / 25 mm, and 0.1 to 0.7 N. / 25 mm is more preferable, and 0.2 to 0.6 N / 25 mm is particularly preferable. The reinforcing film preferably has an adhesive force with respect to the polyimide film in the above range in a state before the pressure-sensitive adhesive layer 2 is photocured. In a flexible display panel, a flexible printed wiring board (FPC), a device in which a display panel and a wiring board are integrated, a flexible substrate material is generally used from the viewpoint of heat resistance and dimensional stability. A polyimide film is used. The reinforcing film having the above adhesive force with respect to the polyimide film as the substrate is easily peeled off from the polyimide adherend before the photocuring of the pressure sensitive adhesive layer 2 and is bonded after photocuring. Excellent reliability.

(Storage modulus)
The pressure-sensitive 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. The shear storage elastic modulus (hereinafter simply referred to as “storage elastic modulus”) is based on the method described in JIS K7244-1 “Plastics—Testing Method for Dynamic Mechanical Properties” under the condition of a frequency of 1 Hz. It is obtained by reading a value at a predetermined temperature when measured at a temperature rising rate of 5 ° C./min in the range of 50 to 150 ° C.

In a material exhibiting viscoelasticity such as an adhesive, the storage elastic modulus G ′ is used as an index representing the degree of hardness. The storage elastic modulus of the pressure-sensitive adhesive layer has a high correlation with the cohesive force. The higher the cohesive force of the pressure-sensitive adhesive, the greater the anchoring force on the adherend. 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 cohesion, so that it has an appropriate wetting speed and is reinforced from the adherend. When the film is peeled off, adhesive residue on the adherend hardly occurs. Moreover, when the storage elastic modulus of the adhesive layer 2 is large, the protrusion of the adhesive from the end face of the reinforcing film can be suppressed. If the storage elastic 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 even when rework is performed. Further, cohesive failure of the pressure-sensitive adhesive layer and adhesive residue on the adherend surface hardly occur. From the viewpoint of enhancing the reworkability of the reinforcing sheet and suppressing the adhesive residue on the adherend during rework, the storage elastic modulus G ′ _i at 25 ° C. before photocuring of the pressure-sensitive adhesive layer 2 is 3 × 10 ⁴ to 1 × 10 ⁵ Pa is more preferable, and 4 × 10 ^{4 to} 9.5 × 10 ⁴ Pa is more preferable.

<Photocuring of adhesive layer>
The adhesive film 2 is photocured by bonding the reinforcing film 10 to the adherend 20 and irradiating the adhesive layer 2 with actinic rays. Examples of the actinic rays include ultraviolet rays, visible light, infrared rays, X-rays, α rays, β rays, and γ rays. Since the curing of the pressure-sensitive adhesive layer in the storage state can be suppressed and the curing is easy, ultraviolet rays are preferable as the actinic rays. What is necessary is just to set the irradiation intensity | strength and irradiation time of actinic light suitably according to a composition, thickness, etc. of an adhesive layer. Irradiation of the actinic ray to the pressure-sensitive adhesive layer 2 may be performed from any surface on the film substrate 1 side and the adherend 20 side, or actinic light may be irradiated from both surfaces.

<Characteristics of pressure-sensitive adhesive layer after photocuring>
(Adhesive strength)
As described above, from the viewpoint of adhesion reliability in practical use of the device, the adhesive force of the pressure-sensitive adhesive layer 2 before photocuring to the glass plate is preferably 1 N / 25 mm or more, more preferably 2 N / 25 mm or more, and 3 N / More preferably, it is 25 mm or more. The reinforcing film preferably has an adhesive force with respect to the polyimide film in the above range in a state after the pressure-sensitive adhesive layer 2 is photocured. The adhesive force between the pressure-sensitive adhesive layer 2 and the adherend after photocuring is preferably 2 times or more, more preferably 3 times or more, and more preferably 5 times the adhesive force between the pressure-sensitive adhesive layer 2 and the adherend before photocuring. The above is more preferable.

The pressure-sensitive adhesive layer 2 preferably has a storage elastic modulus G ′ _f at 25 ° C. after photocuring of 1.5 × 10 ⁵ Pa or more. When the storage elastic modulus of the pressure-sensitive adhesive layer 2 after photocuring is 1.5 × 10 ⁵ Pa or more, the adhesive force with the adherend is improved with an increase in cohesive force, and high adhesion reliability is obtained. . On the other hand, when the storage elastic modulus is excessively large, the pressure-sensitive adhesive hardly spreads and the contact area with the adherend becomes small. Further, since the stress dispersibility of the pressure-sensitive adhesive is reduced, the peeling force tends to propagate to the adhesive interface, and the adhesive force with the adherend tends to be reduced. Therefore, the storage elastic modulus G ′ _f at 25 ° C. after photocuring of the pressure-sensitive adhesive layer 2 is preferably 2 × 10 ⁶ Pa or less. From the viewpoint of enhancing the adhesion reliability of the reinforcing sheet after photocuring the pressure-sensitive adhesive layer, G ′ _f is more preferably 1.8 × 10 ^{5 to} 1.2 × 10 ⁶ Pa, and 2 × 10 ⁵ to 1 × 10. ⁶ Pa is more preferable.

The ratio G ′ _f / G ′ _i of the storage elastic modulus at 25 ° C. before and after photocuring of the pressure-sensitive adhesive layer 2 is preferably 2 or more. If G _'f is G' _i 2 times or more, a large increase in G 'by photocuring may both rework of previous photocuring and adhesion reliability after photocuring. G ′ _f / G ′ _i is more preferably 4 or more, further preferably 8 or more, and particularly preferably 10 or more. The upper limit of G _{'f /} G' _i is not particularly limited, G if _{'f /} G' _i is excessively large, the pre photocurable G 'initial adhesion failure due to small, or G after photocuring' It is easy to lead to the fall of adhesion reliability by being too large. Therefore, G ′ _f / G ′ _i is preferably 100 or less, more preferably 40 or less, further preferably 30 or less, and particularly preferably 25 or less.

  The adherend 20 after the attachment of the reinforcing film 10 may be subjected to heat treatment such as autoclave treatment or thermocompression bonding for circuit member joining for the purpose of improving the affinity of the laminated interfaces of a plurality of laminated members. is there. When such heat treatment is performed, it is preferable that the adhesive between the reinforcing film and the adherend does not flow from the end face.

From the viewpoint of suppressing the protrusion of the pressure-sensitive adhesive during high-temperature heating, the storage elastic modulus at 100 ° C. of the pressure-sensitive adhesive layer 2 after photocuring is preferably 5 × 10 ⁴ Pa or more, more preferably 8 × 10 ⁴ Pa or more. 1 × 10 ⁵ Pa or more is more preferable. In addition to preventing the adhesive from sticking out during heating, the storage elastic modulus at 100 ° C. of the pressure-sensitive adhesive layer 2 after photocuring is 60% of the storage elastic modulus at 50 ° C. The above is preferable, 65% or more is more preferable, 70% or more is further preferable, and 75% or more is particularly preferable.

  In the reinforcing film of the present invention, the pressure-sensitive adhesive layer 2 is photocurable, and the timing of curing can be arbitrarily set. Processing such as rework and processing of the reinforcing film can be performed at any timing after the reinforcing film is pasted on the adherend and before the adhesive is photocured. It can respond flexibly.

  By the photocuring of the pressure-sensitive adhesive layer 2, the reinforcing film 10 is firmly bonded to the adherend 20. Even if an external force is unexpectedly applied due to falling of the device, placing heavy objects on the device, collision of flying objects on the device, etc., the device is prevented from being damaged by the reinforcement film being stuck together. it can. Further, since the pressure-sensitive adhesive layer is firmly adhered, the reinforcing film is hardly peeled even during long-term use, and is excellent in reliability.

  The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[Polymerization of base polymer]
<Polymer A>
In a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas introduction tube, as monomers, 63 parts by weight of 2-ethylhexyl acrylate (2EHA), 15 parts by weight of N-vinylpyrrolidone (NVP), methyl methacrylate (MMA) 9 parts by weight, 13 parts by weight of hydroxyethyl acrylate (HEA), 0.2 part by weight of azobisisobutyronitrile as a polymerization initiator, and 233 parts by weight of ethyl acetate as a solvent were added, and nitrogen gas was passed and stirred. Then, nitrogen substitution was performed for about 1 hour. Then, it heated at 60 degreeC and made it react for 7 hours, and the solution of the acrylic polymer A was obtained.

<Polymer B>
The monomer charge was changed to 95 parts by weight of butyl acrylate (BA) and 5 parts by weight of acrylic acid (AA). Otherwise, polymerization was carried out in the same manner as for polymer A to obtain a solution of acrylic polymer B.

<Polymer C>
As the polyol, 85 parts by weight of a polyether polyol having three hydroxyl groups and a number average molecular weight of 10,000 (“S3011” manufactured by Asahi Glass), 13 parts by weight of a polyether polyol having three hydroxyl groups (“Sanix GP3000” manufactured by Sanyo Chemical) , And 2 parts by weight of a polyether polyol having three hydroxyl groups and a number average molecular weight of 1000 (“SANNICS GP1000” manufactured by Sanyo Chemical), and a polyisocyanate compound, isocyanurate of hexamethylene diisocyanate (“Coronate HX” manufactured by Tosoh) 18 parts by weight, iron (III) acetylacetonate 0.04 parts by weight as a catalyst, and 210 parts by weight of ethyl acetate as a diluent solvent were mixed and stirred at room temperature to obtain a solution of urethane polymer C.

[Example 1]
(Preparation of adhesive composition)
A solution of acrylic polymer A in 300 parts by weight (solid content: 100 parts by weight) and a 75% ethyl acetate solution of trimethylolpropane adduct of xylylene diisocyanate as an isocyanate crosslinking agent (“Takenate D110N” manufactured by Mitsui Chemicals) 3.3 Parts by weight (solid content 2.5 parts by weight), iron (III) acetylacetonate 0.005 parts by weight as a crosslinking catalyst, photo-curing agent (polyfunctional acrylic monomer) 20 parts by weight "Aronix M-321" manufactured by Toagosei As a photopolymerization initiator, 0.1 part by weight of 1-hydroxycyclohexyl phenyl ketone (“Irgacure 184” manufactured by BASF) was added and stirred to prepare a photocurable acrylic pressure-sensitive adhesive solution.

(Production of reinforcing film)
On the 75-micrometer-thick polyethylene terephthalate film ("Lumirror S10" by Toray) which is not surface-treated, said adhesive composition was apply | coated using the fountain roll so that the thickness after drying might be set to 25 micrometers. After removing the solvent by drying at 130 ° C. for 1 minute, a release treatment surface of a separator (a polyethylene terephthalate film having a thickness of 25 μm whose surface was subjected to silicone release treatment) was bonded to the pressure-sensitive adhesive application surface. Thereafter, an aging treatment for 4 days is performed in an atmosphere at 25 ° C., the crosslinking is advanced, a photocurable pressure-sensitive adhesive sheet having a thickness of 25 μm is fixed and laminated on the film substrate, and a separator film is temporarily attached thereon. Obtained.

[Examples 2 to 7 and Comparative Examples 1 to 4]
In the preparation of the pressure-sensitive adhesive composition, a reinforcing film was produced in the same manner as in Example 1 except that the type of the photocuring agent was changed as shown in Table 1. In Comparative Example 4, the addition amount of the isocyanate-based crosslinking agent was changed, and no photocuring agent was added.

[Example 8]
Shin-Nakamura Chemical Co., Ltd. as a polyfunctional acrylic monomer, 300 parts by weight of acrylic polymer B (100 parts by weight solids), 0.5 part by weight of a tetrafunctional epoxy-based crosslinking agent (“Tetrad C” manufactured by Mitsubishi Gas Chemical) 20 parts by weight of “NK Ester A-200” manufactured by KK and 0.1 part by weight of “Irgacure 184” manufactured by BASF as a photopolymerization initiator were added to prepare a photocurable acrylic adhesive solution. Using this pressure-sensitive adhesive solution, a reinforcing film was obtained in the same manner as in Example 1.

[Comparative Example 5]
On a 75 μm thick polyethylene terephthalate film that has not been surface-treated, a solution of urethane polymer C is applied using a fountain roll so that the thickness after drying is 25 μm, and dried at 130 ° C. for 1 minute. After removing the film, the release treatment surface of the separator was bonded to obtain a reinforcing film.

[Evaluation]
The wetting speed of the reinforcing films of Examples and Comparative Examples and the adhesive strength to the glass plate were evaluated by the following methods. Each of the following evaluations was performed in an environment of a class 10000 clean room (temperature 23 ° C., humidity 50% RH).

<Wetting speed>
The adhesive layer at one end in the length direction of the test piece from which the separator was peeled off from the surface of the reinforcing film cut out to a width of 25 mm and a length of 150 mm was brought into contact with a glass plate (“Micro Slide Glass S” manufactured by Matsunami Glass Industrial Co., Ltd.) Then, the other end of the test piece was held by hand so that the angle between the glass plate and the test piece was 20 to 30 °, and the hand was released from the test piece so that the adhesive layer of the test piece was in contact with the glass plate. Record the state of wetting and spreading from one end of the length direction to the other end with a video camera, and calculate the time until the test piece wets and spreads in the length direction of 100 mm (area 25 cm ² ). Was calculated.
Wetting speed (cm ² / sec) = measurement area (25 cm ² ) / wetting spread time (sec)

<Adhesive strength>
A test piece from which the separator was peeled and removed from the surface of the reinforcing film cut out to a width of 25 mm and a length of 100 mm was bonded to a glass plate using a hand roller to obtain a test sample before photocuring. A test sample after photocuring was obtained by photocuring the pressure-sensitive adhesive layer by irradiating ultraviolet rays from the PET film side of the test sample. Using these test samples, the test piece was held with a chuck, the reinforcing film was peeled 180 ° at a tensile speed of 300 mm / min, and the peel strength was measured.

  Table 1 shows the composition and evaluation results of the adhesive of each reinforcing sheet. The addition amount of the crosslinking agent and the photocuring agent in Table 1 is the addition amount (parts by weight) relative to 100 parts by weight of the base polymer. The details of the photocuring agent in Table 1 are as follows.

APG700: “NK Ester APG-700” manufactured by Shin-Nakamura Chemical Co., Ltd., polypropylene glycol # 700 (n = 12) diacrylate; functional group equivalent 404 g / eq
A200: “NK Ester A-200” manufactured by Shin-Nakamura Chemical Co., Ltd., polyethylene glycol # 200 (n = 4) diacrylate; functional group equivalent 154 g / eq
A400: “NK Ester A-400” manufactured by Shin-Nakamura Chemical Co., Ltd., polyethylene glycol # 400 (n = 9) diacrylate; functional group equivalent 254 g / eq
A600: “NK Ester A-600” manufactured by Shin-Nakamura Chemical Co., Ltd., polyethylene glycol # 600 (n = 14) diacrylate; functional group equivalent 354 g / eq
AM130G: “NK ester AM-130G” manufactured by Shin-Nakamura Chemical Co., Ltd., methoxypolyethylene glycol # 550 (n = 13) monoacrylate M321: “Aronix M-321” manufactured by Toagosei Co., Ltd., modified with trimethylolpropane propylene oxide (n = 2) Triacrylate; functional group equivalent 187 g / eq
M350: “Aronix M-350” manufactured by Toagosei Co., Ltd., trimethylolpropane ethylene oxide (n = 1) modified triacrylate; functional group equivalent 129 g / eq
M360: “Aronix M-360” manufactured by Toagosei Co., Ltd., trimethylolpropane ethylene oxide (n = 2) modified triacrylate; functional group equivalent 159 g / eq
PTG9A: Hitachi Chemical “Fancryl FA-PTG9A”, polytetramethylene glycol (n = 9) diacrylate; functional group equivalent 387 g / eq
321A: “Funkryl FA-321A” manufactured by Hitachi Chemical Co., Ltd., ethylene oxide (n = 10) modified bisphenol A diacrylate; functional group equivalent 388 g / eq

  The reinforcing films of Comparative Examples 1 to 3 had a high wetting speed with respect to the glass plate and showed high wettability with respect to the adherend, but the surface of the pressure-sensitive adhesive layer was clouded, and bleeding out of the photocuring agent was observed. . Moreover, in these comparative examples, the adhesive force before photocuring was inadequate, and the adhesive force after photocuring was also inadequate. The reinforcing film of Comparative Example 5 using a urethane-based pressure-sensitive adhesive showed a higher wetting rate than Comparative Examples 1 to 3, but, as with Comparative Examples 1 to 3, the adhesive strength to the glass plate was insufficient. It could not be used as a reinforcing film for the purpose of permanent adhesion to an adherend.

  The reinforcing film of Comparative Example 4 using a pressure-sensitive adhesive containing no photocuring agent showed a high adhesive force when it was pressure-bonded to the glass plate using a hand roller, but only placed on the glass plate without applying pressure. Then, the pressure-sensitive adhesive did not spread on the surface of the glass plate, and the wetting rate could not be measured.

  The reinforcing films of Examples 1 to 8 showed an appropriate wetting rate with respect to the glass plate, and had an adhesive strength before photocuring within an appropriate range, and had both adhesiveness and reworkability. Moreover, after photocuring, it showed high adhesive strength and was suitable as a reinforcing film excellent in adhesion reliability to the device.

  In Example 4, Comparative Example 2 and Comparative Example 3, polyethylene glycol diacrylate was used as a photo-curing agent. In Example 4, good properties were shown, whereas Comparative Example 2 and Comparative Example were shown. In No. 3, the wetting rate was excessively large, and the adhesion to the glass plate was insufficient. As the number of repeating units of ethylene oxide increased, the compatibility between the acrylic base polymer and the photocuring agent decreased, so that in Comparative Examples 2 and 3, the photocuring agent bleeds out to the surface, and adhesion It is considered that the sex has declined.

DESCRIPTION OF SYMBOLS 1 Film base material 2 Adhesive layer 5 Separator 10 Reinforcing film 20 Device (adherent body)

Claims (7)

A film base material, and an adhesive layer fixedly laminated on one main surface of the film base material,
The pressure-sensitive adhesive layer is a photocurable composition comprising a base polymer, a photocuring agent having two or more polymerizable functional groups, and a photopolymerization initiator,
Wetting rate for the glass plate is 0.3 cm ² / sec ~4cm ² / sec, reinforcement film:
Here, the wetting speed is long when the pressure-sensitive adhesive layer of the test piece is in contact with the glass plate from the state where the pressure-sensitive adhesive layer at one end in the length direction of the test piece of width 25 mm × length 150 mm is in contact with the glass plate. It is a value calculated based on the following equation from the wetting and spreading time until wetting and spreading in the range of 100 mm in length from one end to the other end in the vertical direction and a measurement area of 25 cm ² .
Wetting speed (cm ² / sec) = measurement area (25 cm ² ) / wetting spread time (sec)   The reinforcement film of Claim 1 whose adhesive force with respect to the glass plate before photocuring the said adhesive layer is 0.03N / 25mm or more and less than 1N / 25mm.   The reinforcement film of Claim 1 or 2 whose adhesive force with respect to the glass plate after photocuring the said adhesive layer is 1 N / 25mm or more.   The reinforcing film according to claim 1, wherein a crosslinked structure is introduced into the base polymer.   The reinforcing film according to claim 1, wherein the photocurable composition contains an acrylic polymer as the base polymer.   The said photocurable composition is a reinforcement film of any one of Claims 1-5 which contains the said photocuring agent 10-50 weight part with respect to 100 weight part of said base polymers.   The reinforcement film of any one of Claims 1-6 whose said photocuring agent is polyfunctional (meth) acrylate.

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