KR20220136420A - Adhesive sheet having release film and manufacturing method therefor - Google Patents

Abstract

The pressure-sensitive adhesive sheet 1 having a release film includes a first release film 10 temporarily attached to a first main surface of the photo-curing pressure-sensitive adhesive sheet 50 and a second release film temporarily attached to a second main surface of the pressure-sensitive adhesive sheet ( 20) is provided. The pressure-sensitive adhesive sheet includes a photocurable acrylic polymer and a UV absorber. The first release layer 15 of the first release film is a fluorine-based release layer or a condensed silicone release layer. A pressure-sensitive adhesive sheet having a release film is, for example, a photocurable pressure-sensitive adhesive composition comprising an acrylic monomer and/or a partial polymer of an acrylic monomer, a UV absorber, and a photopolymerization initiator, between the first release film and the second release film. It provides in layer form, irradiates light from the 1st release film side, and is obtained by photocuring a photocurable adhesive composition.

Description

Adhesive sheet having release film and manufacturing method therefor

The present invention relates to a pressure-sensitive adhesive sheet to which a release film is temporarily adhered and a method for manufacturing the same.

DESCRIPTION OF RELATED ART The transparent adhesive sheet is used for bonding of optical members for display apparatuses, such as a liquid crystal display and organic electroluminescent display, and input devices for displays, such as a touch panel. A transparent adhesive sheet is generally provided as an adhesive sheet provided with the release film by which the release film was laid on both surfaces. When using the pressure-sensitive adhesive sheet, first, the release film (light release film) on one side is peeled to expose one side of the pressure-sensitive adhesive sheet, and bonding with the first adherend is performed, and the release film (heavy release film) on the other side is peeled off. It peels and bonds a 2nd to-be-adhered body to the other surface of an adhesive sheet.

The optical member used for a display apparatus, an input apparatus, etc. may require ultraviolet-ray blocking property from a viewpoint, such as suppression of the deterioration of the element by an ultraviolet-ray. For example, in an organic electroluminescent display, since deterioration by the ultraviolet-ray of the organic molecule which comprises a light emitting layer etc. has a large influence on a display characteristic, high ultraviolet-blocking property is calculated|required of the optical member arrange|positioned in front of an element. Moreover, in order to prevent deterioration of the polarizer by ultraviolet rays (for example, fading of iodine), the polarizing plate used for a liquid crystal display or an organic electroluminescent display is requested|required of ultraviolet-blocking property of the optical member arrange|positioned in front of a polarizer.

As a method of giving an adhesive sheet the ultraviolet-blocking property, the method of adding a ultraviolet absorber in an adhesive composition is known. For example, patent document 1 describes that the adhesive composition which added the ultraviolet absorber to the heat-polymerizable acrylic adhesive solution was apply|coated as a film|membrane, Then, it heat-dried and obtained the adhesive sheet which has ultraviolet-blocking property. In Patent Document 2, a photocurable acrylic pressure-sensitive adhesive composition containing a photocurable acrylic composition, a photopolymerization initiator, and a UV absorber is photocured in a state sandwiched between two release films, and a photocurable adhesive having UV protection properties It is described that the sheet was obtained.

Japanese Patent Laid-Open No. 2013-75978 Japanese Patent Laid-Open No. 2019-112505

A photocurable adhesive sheet does not require a solvent generally, but is obtained by photocuring (photopolymerization) in the state which laid the base material sheet on both surfaces of the photocurable adhesive composition. Therefore, the photocurable adhesive sheet has the advantage that it is easy to enlarge thickness and can improve smoothness.

However, as also described in Patent Document 2, when photocuring a photocurable pressure-sensitive adhesive composition containing an ultraviolet absorber by irradiating ultraviolet light through a release film to perform photocuring, peeling of the release film on the light-irradiated surface and the pressure-sensitive adhesive sheet after photocuring The force rises significantly, and peeling of a release film may become difficult at the time of bonding with a to-be-adhered body. Although it is proposed in patent document 2 that the peeling force with an adhesive sheet can be reduced by adjusting the thickness of an addition type silicone mold release layer, etc., it is not easy to fully reduce the peeling force with the adhesive sheet after photocuring.

In view of such a subject, this invention has ultraviolet-ray blocking property and aims at provision of the adhesive sheet provided with the release film with favorable peelability with a release film.

The adhesive sheet provided with the release film of this invention is equipped with the 1st release film temporarily adhered to the 1st main surface of the photocurable adhesive sheet which has a 1st main surface and a 2nd main surface, and the 1st main surface of the adhesive sheet. The 1st release film is equipped with the 1st release layer on the 1st film base material, The 1st release layer and the adhesive sheet are in contact. The adhesive sheet provided with the release film may be equipped with the 2nd release film temporarily adhered to the 2nd main surface of the adhesive sheet. The pressure-sensitive adhesive sheet contains a photocurable acrylic polymer and an ultraviolet absorber.

The 1st main surface of an adhesive sheet is a light irradiation surface at the time of photocuring a photocurable adhesive composition. That is, a photocurable adhesive sheet is formed by performing light irradiation with respect to a photocurable adhesive composition through a 1st release film. The 1st release layer of the 1st release film laid on the side of the light irradiation surface with respect to the photocurable adhesive composition is a fluorine-type release layer or a condensation-type silicone release layer. The second release layer of the second release film may be a non-fluorine-based addition type silicone release layer.

As for the light transmittance of wavelength 380nm of an adhesive sheet, 50 % or less is preferable. The adhesive sheet may contain 0.1-10 weight part of ultraviolet absorbers with respect to 100 weight part of acrylic polymers. The acrylic polymer of the adhesive sheet may contain the polyfunctional monomer component which has two or more polymerizable functional groups in 1 molecule as a monomer component.

By performing light irradiation to the photocurable pressure-sensitive adhesive composition from the first release film side in a state in which the first release layer of the first release film is in contact with the first main surface of the photocurable pressure-sensitive adhesive composition layer, the release film is provided An adhesive sheet is obtained. A photocurable adhesive composition contains an acrylic material, a ultraviolet absorber, and a photoinitiator. As an acryl-type material contained in a photocurable adhesive composition, an acryl-type monomer and its partial polymer are mentioned. The acrylic material may contain both the acrylic monomer and the partial polymer of the acrylic monomer.

In one embodiment, by irradiating light from the first release film side to the laminate in which the photocurable pressure-sensitive adhesive composition layer is sandwiched between the first release film and the second release film, and photocuring the photocurable pressure-sensitive adhesive composition, both sides The adhesive sheet to which the release film was temporarily adhered is obtained. In the adhesive sheet by which the release film was temporarily adhered to both surfaces, the peeling force (peel strength) of a 1st release film and an adhesive sheet may be larger than the peeling force of a 2nd release film and an adhesive sheet.

The adhesive sheet which has a high visible light transmittance|permeability and has ultraviolet-blocking property is used suitably as an optical adhesive sheet for display devices or display input devices which are requested|required of ultraviolet-blocking property. In the pressure-sensitive adhesive sheet provided with the release film of the present invention, since excessive rise in the peeling force between the pressure-sensitive adhesive sheet and the first release film is suppressed, peeling of the release film from the pressure-sensitive adhesive sheet and workability of bonding the pressure-sensitive adhesive sheet to the adherend. this is excellent

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the lamination|stacking structure of the adhesive sheet provided with a release film.

The adhesive sheet provided with the release film of this invention is equipped with the release film temporarily adhered to each both surfaces of the adhesive sheet. "Temporary adhesion" means the state adhere|attached so that peeling is possible. 1 is a cross-sectional view of a pressure-sensitive adhesive sheet 1 provided with a release film to which release films 10 and 20 are temporarily attached to both surfaces of the pressure-sensitive adhesive sheet 50 . The pressure-sensitive adhesive sheet 50 is formed in the form of an adhesive sheet. 85 % or more is preferable and, as for the total light transmittance of the adhesive sheet 50, 90 % or more is more preferable. 2% or less is preferable and, as for the haze of an adhesive sheet, 1 % or less is more preferable. A total light transmittance and a haze are measured according to JISK7136 using a haze meter.

The adhesive sheet 50 is an acrylic adhesive including a photocurable acrylic polymer. The acrylic pressure-sensitive adhesive sheet consists of a photocurable pressure-sensitive adhesive obtained by layering a photocurable pressure-sensitive adhesive composition containing an acrylic monomer and/or a partial polymer (prepolymer) of an acrylic polymer, and a photopolymerization initiator, and photocuring. In the present specification, the "photocurable" adhesive refers to a photocurable adhesive containing a photopolymerizable functional group-containing compound such as a vinyl group or a (meth)acryloyl group, and a "photocured" adhesive The term refers to the pressure-sensitive adhesive after photocuring the photocurable pressure-sensitive adhesive. In addition, in the adhesive after superposing|polymerizing a photocurable adhesive, when a part of a photopolymerizable compound remains unreacted, the adhesive may be photocured and also photocurable.

[Photocurable pressure-sensitive adhesive composition]

The photocurable adhesive composition contains a photopolymerizable acrylic material, a ultraviolet absorber, and a photoinitiator.

<Photopolymerizable acrylic material>

As a photopolymerizable acrylic material contained in a photocurable adhesive composition, an acryl-type monomer and its partial polymerization product (prepolymer) are mentioned.

(monomer component)

As the acrylic monomer, (meth)acrylic acid alkylester having 1 to 20 carbon atoms in the alkyl group is preferably used. In the (meth)acrylic acid alkylester, the alkyl group may have a branch. It is preferable that it is 40 weight% or more with respect to the monomer component whole quantity of an acrylic material, as for content of (meth)acrylic-acid alkylester, 50 weight% or more is more preferable, and its 60 weight% or more is still more preferable.

In addition to (meth)acrylic acid alkylester, high polarity monomers, such as a hydroxyl-containing monomer and a nitrogen-containing monomer, may be contained as a copolymerization component. When the acrylic polymer contains a high-polarity monomer unit, the cohesive force of the pressure-sensitive adhesive is improved to increase the adhesiveness of the pressure-sensitive adhesive sheet to the adherend, and the cloudiness of the pressure-sensitive adhesive under a high-temperature, high-humidity environment is suppressed, and the transparency of the pressure-sensitive adhesive sheet is improved. There is this.

As the hydroxyl group-containing monomer, (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 4-hydroxybutyl, (meth)acrylic acid 6-hydroxyhexyl, (meth)acrylic acid 8 -hydroxyoctyl, (meth)acrylic acid 10-hydroxydecyl, (meth)acrylic acid 12-hydroxylauryl, (4-hydroxymethylcyclohexyl)-methyl acrylate, etc. are mentioned. 1 to 40 weight% is preferable with respect to monomer component whole quantity, as for content of a hydroxyl-group containing monomer, 3 to 30 weight% is more preferable, 5 to 20 weight% is still more preferable.

Examples of the nitrogen-containing monomer include N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmor. Vinyl-based monomers such as poline, (meth)acryloylmorpholine, N-vinylcarboxylic acid amides, and N-vinylcaprolactam, and cyanoacrylate-based monomers such as acrylonitrile and methacrylonitrile can be heard It is preferable that a nitrogen-containing monomer has a cyclic structure containing a nitrogen atom, and especially, lactam-type vinyl monomers, such as N-vinylpyrrolidone, are preferable. 0.5 to 50 weight% is preferable with respect to monomer component whole quantity, as for content of a nitrogen-containing monomer, 1 to 40 weight% is more preferable, 3 to 30 weight% is still more preferable.

As a copolymerization monomer component, you may contain monomers other than the above, such as a carboxyl group containing monomer, a cyclic ether group containing monomer, and a silane type monomer.

The copolymerization monomer component may contain the polyfunctional polymerizable compound which has 2 or more polymerizable functional groups in 1 molecule. Examples of the polyfunctional polymerizable compound include a compound having two or more C=C bonds in one molecule, and a compound having one C=C bond and a polymerizable functional group such as epoxy, aziridine, oxazoline, hydrazine, and methylol. and the like. Among them, a polyfunctional polymerizable compound having two or more C=C bonds in one molecule is preferable. The polyfunctional polymerizable compound may exist in an adhesive composition as a monomer or an oligomer, and may couple|bond with functional groups, such as a hydroxyl group of a prepolymer component.

Examples of the polyfunctional polymerizable compound having two or more C=C bonds in one molecule include (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, and neopentyl glycol di(meth) Acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6 - Polyfunctional (meth), such as hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate and acrylates (ester compounds of polyhydric alcohol and (meth)acrylic acid). Polyfunctional (meth)acrylate may have a (meth)acryloyl group at the terminal of polymer chains, such as epoxy (meth)acrylate, polyester (meth)acrylate, and urethane (meth)acrylate.

Although the usage-amount of a polyfunctional monomer changes with the molecular weight, the number of functional groups, etc., 5 weight% or less is preferable with respect to the monomer component whole quantity, 3 weight% or less is more preferable, and its 2 weight% or less is still more preferable. The amount of the polyfunctional monomer used may be 0.001 wt% or more, 0.01 wt% or more, or 0.05 wt% or more, based on the total amount of the monomer component.

The photocurable adhesive composition WHEREIN: Said monomer component may exist as a partial polymer (prepolymer). A prepolymer is what polymerized a part of a monomer component. When a monomer component exists as a prepolymer, the viscosity of a photocurable adhesive composition can be adjusted to the range suitable for application|coating on a support body.

A prepolymer can be prepared, for example by partially polymerizing the composition for prepolymer formation which mixed the monomer component and the polymerization initiator. The composition for prepolymer formation may contain all the monomer components which comprise an acrylic polymer, and may contain only a part of the monomer which comprises an acrylic polymer. When the monomer component constituting the acrylic polymer contains a monofunctional monomer and a polyfunctional monomer, the pressure-sensitive adhesive composition may be prepared by adding a polyfunctional monomer to the prepolymer composition obtained by partial polymerization of only the monofunctional monomer. By adding a polyfunctional monomer to the prepolymer composition obtained by partial polymerization of only the monofunctional monomer and performing post-polymerization, the crosslinking point of the polyfunctional monomer can be uniformly introduced into the polymer. A part of the polyfunctional monomer component constituting the acrylic polymer may be contained in the composition for forming the prepolymer, and after polymerization of the prepolymer, the remainder of the polyfunctional monomer component may be added to perform post-polymerization.

The prepolymer may be prepared by polymerization in two or more steps or in three or more steps. For example, after prepolymerizing only a monofunctional monomer, a polyfunctional monomer may be added to perform partial polymerization to prepare a prepolymer composition, and if necessary, a monomer component or the like may be further added to perform post polymerization.

The polymerization method of the prepolymer is not particularly limited. From a viewpoint of adjusting reaction time and making the molecular weight (polymerization rate) of a prepolymer into a desired range, the photopolymerization by actinic light irradiation, such as an ultraviolet-ray, is preferable. When performing photopolymerization, it is preferable that the composition for prepolymer formation contains a photoinitiator. The specific example of a photoinitiator is mentioned later.

The composition for prepolymer formation may contain the chain transfer agent etc. as needed other than a monomer component and a polymerization initiator. The chain transfer agent receives a radical from the growing polymer chain to stop the elongation of the polymer, and the chain transfer agent that has received the radical has an action of attacking the monomer to start polymerization again. By using a chain transfer agent, excessive increase in molecular weight can be suppressed, without reducing the radical concentration in a reaction system. As the chain transfer agent, α-thioglycerol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, thioglycolic acid 2-ethylhexyl, 2,3-dimercapto-1- Thiols, such as propanol, are used suitably.

Although the polymerization rate of a prepolymer is not specifically limited, From a viewpoint of setting it as the viscosity suitable for application|coating on a support body, 3 to 50 % is preferable and 5 to 40 % is more preferable. The polymerization rate of a prepolymer can be adjusted to a desired range by adjusting the kind, usage-amount of a photoinitiator, irradiation intensity, irradiation time, etc. of actinic rays, such as an ultraviolet-ray. A polymerization rate is computed by the following formula from the weight before and behind heating (drying) when a prepolymer composition is heated at 130 degreeC for 3 hours. In addition, in the case of performing partial polymerization by solution polymerization, the polymerization rate is calculated by subtracting the amount of the solvent from the total weight of the prepolymer composition as the weight before heating in the following formula.

Polymer polymerization rate (%) = 100 x (weight after heating / weight before heating)

<Preparation of photocurable adhesive composition>

A photocurable pressure-sensitive adhesive composition is obtained by mixing the remaining monomer component, an ultraviolet absorber, a photoinitiator, and other additives with the above photopolymerizable acrylic material (monomer and/or a partial polymer thereof). It is preferable that the photocurable adhesive composition contains the above-mentioned polyfunctional monomer as a monomer component of remainder.

<Ultraviolet absorbent>

Examples of the ultraviolet absorber include a benzotriazole-based ultraviolet absorber, a benzophenone-based ultraviolet absorber, a triazine ultraviolet absorber, a salicylate-based ultraviolet absorber, and a cyanoacrylate-based ultraviolet absorber. A triazine-based UV absorber and a benzotriazole-based UV absorber are preferable from the viewpoint of high UV absorption, excellent compatibility with the acrylic polymer, and easy to obtain a highly transparent acrylic pressure-sensitive adhesive. A triazine-based ultraviolet absorber and a benzotriazole-based ultraviolet absorber having one benzotriazole skeleton per molecule are preferable.

You may use a commercial item as a ultraviolet absorber. Commercially available triazine-based UV absorbers include 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl and [(alkyloxy) Reaction product of methyl]oxirane ("TINUVIN 400" manufactured by BASF, 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-tria Reaction product of Jinwa (2-ethylhexyl)-glycidic acid ester ("TINUVIN 405" manufactured by BASF), (2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-) Dibutoxyphenyl)-1,3,5-triazine ("TINUVIN 460" manufactured by BASF, 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl) ) oxy]-phenol ("TINUVIN 577" manufactured by BASF, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1, 3,5-triazine ("TINUVIN 479" manufactured by BASF, 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl) )-1,3,5-triazine ("Tinosorb S" manufactured by BASF, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-) Ethylhexanoyloxy)ethoxy]-phenol ("ADK STAB LA-46" by ADEKA) etc. are mentioned.

As a commercially available product of the benzotriazole-based ultraviolet absorber, 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl ) Phenol ("TINUVIN 928" manufactured by BASF, 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole ("TINUVIN PS" manufactured by BASF, 2-(2H-benzotriazole-2-) yl)-4,6-bis(1-methyl-1-phenylethyl)phenol ("TINUVIN 900" manufactured by BASF, 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1- Phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol ("TINUVIN 928" manufactured by BASF, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl Phenol (“TINUVIN571” manufactured by BASF, 2-(2H-benzotriazol-2-yl)-p-cresol (“TINUVIN P” manufactured by BASF, 2-(2H-benzotriazol-2-yl)-4-6) -Bis(1-methyl-1-phenylethyl)phenol ("TINUVIN 234" manufactured by BASF, 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl) ) Phenol ("TINUVIN 326," manufactured by BASF, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol ("TINUVIN 328," manufactured by BASF, 2-(2H-benzotria)) Zol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol ("TINUVIN 329" manufactured by BASF), benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5 -(1,1-dimethylethyl)-4-hydroxy (C7-9 branched and straight chain alkyl) ester compound ("TINUVIN384-2" manufactured by BASF), methyl-3-(3-(2H-benzotriazole- 2-yl)-5-t-butyl-4-hydroxyphenyl) reaction product of propionate and polyethylene glycol ("TINUVIN1 130" manufactured by BASF), methyl 3-(3-(2H-benzotriazole-2- yl)-5-tert-butyl-4-hydroxyphenyl) a reaction product of propionate and polyethylene glycol 300 ("TINUVIN 213" manufactured by BASF, 2-[2-hydroxy-3-(3,4,5, 6-tetrahydrophthalimidemethyl)-5-methylphenyl]benzotriazole ("Sumisorb250" by Sumitomo Chemical) etc. are mentioned.

0.1-10 weight part is preferable with respect to 100 weight part of monomer components, as for content of the ultraviolet absorber in a photocurable adhesive composition, 0.3-7 weight part is more preferable, 0.5-5 weight part is still more preferable. By making content of a ultraviolet absorber into the said range, the ultraviolet blocking property of an adhesive sheet can be improved, suppressing the fall of transparency by the bleed-out of a ultraviolet absorber, etc. Moreover, the fall of the polymerization rate of an adhesive composition as content of a ultraviolet absorber is in the said range can be suppressed.

<Photoinitiator>

The photocurable adhesive composition contains a photoinitiator. A photoinitiator is an optical radical generating agent which generate|occur|produces a radical by visible light or ultraviolet-ray of wavelength shorter than wavelength 450nm.

When the photocurable pressure-sensitive adhesive composition contains a UV absorber, a part of the irradiation light for photocuring is absorbed by the UV absorber. From the viewpoint of promoting the generation of radicals by cleavage of the photopolymerization initiator and improving the polymerization rate, it is preferable to use a photopolymerization initiator having sensitivity in a wavelength region where absorption by the ultraviolet absorber is small. Specifically, it is preferable that a photoinitiator has a sensitivity to a wavelength longer than wavelength 380 nm, and it is more preferable to have a sensitivity to a wavelength longer than 400 nm. It is preferable to use a photoinitiator having an extinction coefficient of 1×10 ² [mLg ^-1 cm ^-1 ] or more at a wavelength of 405 nm. The photoinitiator which has the photosensitivity of a long wavelength may have the sensitivity with respect to the light with a wavelength of 400 nm or less.

As a specific example of the photoinitiator which has a photosensitivity of wavelength 400 nm or more, 2,4,6- trimethylbenzoyl diphenylphosphine oxide (BASF "Lucirin TPO", 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide (BASF) Acyl phosphine oxides such as "Lucirin TPO-L" manufactured by BASF, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1 ("Irgacure 369" manufactured by BASF), etc. aminoketones of: bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide ("Irgacure 819" manufactured by BASF, 2,2-dimethoxy-1,2-diphenylethan-1-one (BASF) Bisacylphosphine oxides, such as "Irgacure 651"), bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide ("CGI403" manufactured by BASF), etc. are mentioned. have.

As the photopolymerization initiator, those having long wavelength light sensitivity and those having no long wavelength light sensitivity (for example, those having an extinction coefficient of less than 1×10 ² [mLg ^-1 cm ^-1 ] at a wavelength of 405 nm) are used in combination. You may use it.

Examples of the photopolymerization initiator that do not have long-wavelength photosensitivity include a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, and a benzophenone-based photopolymerization initiator. A photoinitiator, a ketal type photoinitiator, a thioxanthone type photoinitiator, an acylphosphine oxide type photoinitiator, a titanocene type photoinitiator, etc. are mentioned.

0.02-10 weight part is preferable with respect to a total of 100 weight part of the monomer component and prepolymer component which comprise an acrylic polymer, and, as for content of the photoinitiator in a photocurable adhesive composition, 0.05-5 weight part is more preferable. When there are too few photoinitiators, a polymerization rate may become inadequate, and when there are too many photoinitiators, the molecular weight of a polymer may become low and the adhesive force of an adhesive may become inadequate.

As mentioned above, also in preparation (partial polymerization) of a prepolymer, a photoinitiator can be used. The photoinitiator used for partial polymerization may be the same as or different from the photoinitiator added to a photocurable adhesive composition. When the ultraviolet absorber is not included in the composition for forming a prepolymer and the ultraviolet absorber is added after partial polymerization, the photopolymerization initiator used for partial polymerization does not need to have long wavelength light sensitivity. You may use the unreacted material of the photoinitiator used for partial polymerization as a photoinitiator in a photopolymerizable adhesive composition as it is.

It is preferable to add a ultraviolet absorber to the prepolymer composition after partial polymerization without including a ultraviolet absorber in the composition for prepolymer formation from a viewpoint of utilization efficiency of irradiation light, etc. For example, partial polymerization is performed using a photopolymerization initiator that does not have long wavelength light sensitivity as a pre-addition polymerization initiator, and a photopolymerization initiator having long-wavelength light sensitivity as a UV absorber and a post-addition polymerization initiator is added to the composition after partial polymerization. After adding and preparing a photocurable adhesive composition and apply|coating a photocurable adhesive composition layer-wise on a base material, it is preferable to perform post-polymerization.

<Other ingredients>

A chain transfer agent may be contained in the photocurable adhesive composition. The chain transfer agent contained in the photocurable adhesive composition is not specifically limited, For example, the chain transfer agent mentioned above can be used.

The photocurable adhesive composition may contain various oligomers for the purpose of adjustment, viscosity adjustment, etc. of the adhesive force of an adhesive. As an oligomer, the thing of about 1000-30000 weight average molecular weights is used, for example. As an oligomer, an acryl-type oligomer is preferable at the point which is excellent in compatibility with an acryl-type polymer.

In addition to the above, additives, such as a silane coupling agent, a crosslinking agent, a tackifier, a plasticizer, and a softener, may be contained in the photocurable adhesive composition. Moreover, the adhesive composition may contain additives, such as a deterioration inhibitor, a filler, a coloring agent, antioxidant, surfactant, and an antistatic agent, in the range which does not impair the characteristic of an adhesive.

It is preferable that the photocurable adhesive composition has a viscosity (for example, about 5-100 poise) suitable for application|coating on a base material. The viscosity of the pressure-sensitive adhesive composition can be adjusted by, for example, addition of various polymers such as thickening additives and polyfunctional monomers, polymerization rate of the prepolymer, and the like. The content of the acrylic monomer component (a partial polymer of an acrylic monomer and an acrylic monomer) in the photocurable pressure-sensitive adhesive composition is preferably 50% by weight or more, more preferably 70% by weight or more, and still more preferably 80% by weight or more.

[Formation of the adhesive sheet]

An adhesive sheet is obtained by apply|coating a photocurable adhesive composition on a support body, or forming an adhesive composition layer between a support body and a cover sheet, irradiating an active energy ray to an adhesive composition, and photocuring. Examples of the coating method of the pressure-sensitive adhesive composition include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating. can

Although the application|coating thickness (thickness of the adhesive sheet 50) of a photocurable adhesive composition is not specifically limited, For example, it is about 10-500 micrometers. From a viewpoint of improving the ultraviolet absorbency by an adhesive sheet, as for the thickness of an adhesive sheet, 50 micrometers or more are preferable. 50 % or less is preferable, as for the light transmittance in wavelength 380 nm of the adhesive sheet 50, 30 % or less is more preferable, 10 % or less is still more preferable, 5 % or less, or 3 % or less may be sufficient as it.

An adhesive sheet is obtained by irradiating an ultraviolet-ray and/or short wavelength visible light to the laminated body provided with the photocurable acrylic adhesive composition layer on a support base material, and photocuring. When the photocurable pressure-sensitive adhesive composition layer is photocured by light irradiation with respect to the laminate sandwiched between the supporting substrate and the cover sheet, light irradiation may be performed from either side of the supporting substrate side or the cover sheet side, and from both sides. You may perform light irradiation. As will be explained in detail later, in the present invention, a release film 10 provided with a predetermined release layer 15 is used as a supporting base material or a cover sheet to be laid on the light-irradiated surface side of the pressure-sensitive adhesive sheet.

From the viewpoint of improving the curing rate, the light irradiation intensity is preferably 5 mW/cm ² or more. The light irradiation intensity is preferably 20 mW/cm ² or less from the viewpoint of sufficiently increasing the molecular weight of the acrylic polymer after photocuring and securing the holding power at high temperature.

As for the accumulated light quantity of irradiation light, about 100-5000 mJ/cm< ² > is preferable. A light source for light irradiation is not particularly limited as long as the photopolymerization initiator contained in the pressure-sensitive adhesive composition can irradiate light in a wavelength range having a sensitivity, and an LED light source, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a metal halide lamp, a xenon lamp etc. are preferably used.

Most of the ultraviolet light irradiated to the photocurable adhesive composition containing a ultraviolet absorber is absorbed by a ultraviolet absorber. It is preferable to irradiate light in a wavelength region in which light absorption by the ultraviolet absorber is small from the viewpoint of suppressing the reduction in molecular weight due to a rise in temperature and improving the utilization efficiency and curing rate of the irradiated light. It is preferable to use an LED light source from the viewpoint that there is little heat radiation from a light source and can irradiate light with a small wavelength width|variety. When using an LED light source, 350 nm or more of the emission peak wavelength is preferable, and 360 nm or more, 380 nm or more, or 400 nm or more may be sufficient.

90 % or more is preferable, as for the final polymerization rate of the monomer component in the adhesive sheet after photocuring, 95 % or more is more preferable, and 98 % or more is still more preferable. 50 % or more is preferable, as for the gel fraction of an adhesive sheet, 75 % or more is more preferable, and 85 % or more is still more preferable.

[Release Film]

As a support base material for apply|coating a pressure-sensitive adhesive composition, and a cover sheet laid on the surface of the application layer of the pressure-sensitive adhesive composition, a release film having a release layer on the contact surface with the application layer (adhesive sheet) of the pressure-sensitive adhesive composition is used. In the present invention, a release film (first release film) 10 provided with a predetermined first release layer 15 is laid on the first main surface (light irradiation surface side) of the photocurable pressure-sensitive adhesive composition layer 55 . In one state, photocuring is performed. On the 2nd main surface of the photocurable adhesive composition layer 55, the release film (2nd release film) 20 provided with the 2nd release layer 25 is laid.

<Film substrate>

As the film base materials 11 and 21 of the release films 10 and 20, various resin films having transparency are used. Examples of the resin material include polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, ( and meth)acrylic resins, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyarylate-based resins, and polyphenylene sulfide-based resins. Among these, polyester-type resins, such as a polyethylene terephthalate, are especially preferable. 10-200 micrometers is preferable and, as for the thickness of the film base materials 11 and 21, 25-150 micrometers is more preferable.

<Release layer>

As a material of the mold release layers 15 and 25, a silicone resin, a long-chain alkyl-type resin, a fatty acid amide resin, etc. are mentioned. These resins may contain the fluorine atom in the side chain of a polymer. For example, the fluorinated silicone resin containing a fluorine atom in a side chain may be sufficient as silicone resin.

The silicone-based mold release agent used in the formation of the silicone-based release layer is largely classified into a condensation-type silicone-based mold release agent and an addition-type silicone-based mold release agent according to the type of curing reaction (crosslinking reaction) of the polyorganosiloxane as its main component.

For the formation of the addition-type silicone-based release layer, a silicone-based resin composition that is cured by addition reaction is used. A silicone-based resin composition that is cured by addition reaction includes a polyorganosiloxane resin having an alkenyl group such as a vinyl group or a hexenyl group, and a polyorganosiloxane compound (crosslinking agent) having a hydrosilyl group (SiH), , it is also preferred to include a curing catalyst (hydrosilylation catalyst). This silicone resin composition forms a peelable film (release layer) by reaction (hydrosilylation reaction) of the alkenyl group of polyorganosiloxane resin, and the hydrosilyl group of a crosslinking agent by heating.

Examples of the polyorganosiloxane include polyalkylalkylsiloxanes such as polydimethylsiloxane, polydiethylsiloxane, and polymethylethylsiloxane; polyalkylarylsiloxanes; and poly(dimethylsiloxane-diethylsiloxane). Among these, polydimethylsiloxane is preferable. The polyorganosiloxane may be one in which a plurality of types of organic groups are bonded to one Si atom.

The crosslinking agent is a polyorganosiloxane having a hydrosilyl group, and preferably has two or more silicon atoms having a Si-H bond in one molecule. As polyorganosiloxane which has a hydrosilyl group, polymethylhydrogensiloxane, poly(dimethylsiloxane-methylhydrogensiloxane), hydrosilyl group terminal polydimethylsiloxane, etc. are preferable.

You may use the commercial item in which the polyorganosiloxane resin which has an alkenyl group, and the polyorganosiloxane compound which has a hydrosilyl group were mixed previously. As a commercial item containing a polyorganosiloxane resin having an alkenyl group and a polyorganosiloxane compound having a hydrosilyl group, "KS-847" and "X-62-2829" manufactured by Shin-Etsu Chemical Co., Ltd., and Toray Dow Corning "SRX211", "LTC761", "LTC300B", etc. are mentioned.

As a catalyst for addition reaction (hydrosilylation reaction), a platinum-type catalyst is preferable. Examples of the platinum-based catalyst include chloroplatinic acid, an olefin complex of platinum, and an olefin complex of chloroplatinic acid.

A silicone-based resin composition that is cured by a condensation reaction is used to form the condensation-type silicone-based release layer. Examples of the silicone-based resin composition that is cured by condensation reaction include a polyorganosiloxane resin having a silanol group at the molecular terminal, polymethylhydrogensiloxane, a cellulose derivative, an alkyd resin, and the like, and a curing catalyst may be included.

As the polyorganosiloxane having a silanol group at the molecular terminal, as a functional group (organic group) of the side chain, an alkyl group such as a methyl group or an ethyl group, a phenyl group, or the like is preferably introduced. The condensed silicone resin composition may contain the alkoxy group-containing polyorganosiloxane functioning as a crosslinking agent.

As a catalyst for a condensation reaction, an organotin catalyst is preferable. Examples of the organic tin catalyst include dibutyl tin dilaurate, dibutyl tin diacetate, and dibutyl tin dioctate.

The resin composition containing a fluorine resin is used for formation of a fluorine-type mold release layer. The fluororesin contains a fluorine atom in the side chain portion of the polymer, and specific examples thereof include a fluorine-containing hydrocarbon resin such as polytetrafluoroethylene, and a fluorinated silicone resin. From a viewpoint of peelability from an adhesive sheet, a fluorinated silicone resin is preferable.

A curable type may be sufficient as a fluorinated silicone resin, and a non-curing type may be sufficient as it. A curable fluorinated silicone resin (hardened|cured material of curable fluorinated silicone) is preferable at the point which has high adhesiveness with a film base material and can form a strong film|membrane. As the curable fluorinated silicone resin, an addition type silicone is preferable. For example, in the above addition type silicone composition, a part or all of the alkyl group of the side chain of the polyorganosiloxane is substituted with a fluorine atom or a fluoroalkyl group is used.

Commercially available curable fluorinated silicone resins include "KP-911" and "X-70-201S" manufactured by Shin-Etsu Chemical Co., and "FS1265-300CS", "FS1265-1000CS", and "FS1265-" manufactured by Toray Dow Corning. 10000CS", "BY24-900", "BY24-903" "Syl-off 3062", "Q2-7785", etc. are mentioned.

The composition (release agent composition) for forming a mold release layer may contain the organic solvent in addition to a resin component. Examples of the organic solvent include hydrocarbon solvents such as cyclohexane, n-hexane and n-heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; Alcohol solvents, such as methanol, ethanol, and a butanol, etc. are mentioned. A mixed solvent may be sufficient as an organic solvent.

The mold release agent composition may contain various additives, such as a filler, an antistatic agent, antioxidant, a plasticizer, and a coloring agent, as needed.

A mold release layer is formed by apply|coating a mold release agent composition on a film base material, and performing heat-drying and hardening reaction as needed. Examples of the coating method include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating. As a heat-drying method, hot air drying is mentioned. Although the conditions of hot air drying vary with the heat resistance of a base material, it is about 80-150 degreeC normally, and it is about 10 second - about 10 minutes. If necessary, for the purpose of accelerating the curing reaction or the like, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination.

As mentioned above, when photocuring the photocurable adhesive composition layer 55, light is irradiated from the 1st release film 10 side. The first release layer 15 of the first release film 10 is preferably a fluorine-based release layer or a condensed silicone release layer. The silicone resin of the condensed silicone mold release layer may be either fluorine-based or non-fluorine-based. When the first release layer 15 is a fluorine-based release layer or a condensed silicone release layer, the peeling force from the photocurable pressure-sensitive adhesive sheet is smaller than when a release film having a non-fluorine-based additive silicone release layer is used. tends to

Although the 2nd release layer 25 of the 2nd release film 20 is not specifically limited, From the point which shows the peeling force of a moderate degree, a fluorine-free addition type silicone release layer is preferable. The first release layer 15 of the first release film 10 (jungbak film) on the light-irradiated surface is a fluorine-based release layer or a condensed silicone release layer, and the second release film 20 on the opposite surface (light release film) ), when the second release layer 25 is a non-fluorine-based addition silicone release layer, it is easy to peel the first release film 10 from the photocurable pressure-sensitive adhesive layer 50, and the peeling force of the first release film The adhesive sheet provided with the release film with an appropriate balance of the peeling force of and a 2nd release film is obtained.

[Peelability of release film and adhesive sheet]

In a pressure-sensitive adhesive sheet having a release film in which a release film is temporarily adhered to both surfaces of the pressure-sensitive adhesive sheet, in general, the peeling force between the pressure-sensitive adhesive sheet and one release film is relatively higher than the peeling force between the pressure-sensitive adhesive sheet and the other release film. small. When using the pressure-sensitive adhesive sheet, the release film (low-peel film) with a low peel force is peeled from the pressure-sensitive adhesive sheet and bonded to the first adherend, and then the release film (medium peel film) with a relatively large peel force is peeled off Thus, bonding with the second adherend is performed. By providing a difference in peeling force in the release film temporarily adhered to the front and back sides of the pressure-sensitive adhesive sheet, the light peeling film can be selectively peeled at the time of bonding with the first adherend, so that the workability of bonding can be improved. .

In the photocurable adhesive sheet, since the adhesive strength of the adhesive is different before and after photocuring, in consideration of the adhesive properties of the adhesive sheet after photocuring, the adhesiveness (peelability) gender) is adjusted. When an adhesive composition does not contain a ultraviolet absorber, the magnitude relationship of the peeling force of one release film and the other release film does not change before and behind photocuring. On the other hand, when the photocurable pressure-sensitive adhesive composition contains an ultraviolet absorber, the increase in the peeling force of the first release film 10 on the light-irradiated surface side of the second release film 20 disposed on the opposite surface It tends to become remarkably large compared with the increase in peeling force.

Therefore, in the adhesive sheet provided with a release film, it is preferable to make the 1st release film 10 of a light irradiation surface into a heavy release film, and to make the 2nd release film 20 of an opposite surface a light release film. That is, it is preferable that the peeling force of the 1st release film 10 and the adhesive sheet 50 is larger than the peeling force of the 2nd release film 20 and the adhesive sheet 50 .

As described above, light irradiation to the pressure-sensitive adhesive composition may be performed from either side of the support base material side and the cover sheet side, or light irradiation may be performed from both surfaces. When irradiating light from the support base material side, what is necessary is just to use the 1st release film 10 provided with said 1st release layer 15 as a support base material which apply|coats an adhesive composition. What is necessary is just to use the 1st release film 10 provided with the said 1st release layer 15 as a cover sheet to be laid on the adhesive composition layer 55, when light-irradiating from the cover sheet side.

When irradiating light from both surfaces, what is necessary is just to use said 1st release film for either a support base material or a cover sheet. You may use the release film provided with a fluorine-type mold release layer or a condensed silicone mold release layer for both a support base material and a cover sheet. As described in Japanese Patent Application Laid-Open No. 2014-65754, when light is irradiated to both sides while conveying a folded pass line that reverses the conveying direction, the release film is first applied to the light-irradiated side. It is preferable to use

When the peeling force between the first release film 10 (jungbak peeling film) and the pressure-sensitive adhesive sheet 50 is excessively large, the pressure-sensitive adhesive sheet 50 is separated from the surface of the pressure-sensitive adhesive sheet 50 in a state in which the pressure-sensitive adhesive sheet 50 is bonded to the first adherend. When peeling the 1st release film 10, the deformation|transformation of an adhesive sheet, whitening, problems, such as peeling of an adhesive sheet from a to-be-adhered body, may be produced. 0.1-1N/50mm is preferable, as for the peeling force (peel strength) of the 1st release film 10 from the adhesive sheet 50 after photocuring, 0.2-0.8N/50mm is more preferable, 0.3-0.7N/50mm is more preferable. is more preferable. The peeling force of a release film and an adhesive sheet is a measured value by the 180 degree peel test of tensile speed: 0.3 m/min. As described above, when the release layer 15 of the first release film 10 is a fluorine-based release layer or a condensed silicone release layer, the adhesive sheet 50 and the first release film 10 after photocuring. can suppress excessive elevation of

When the photocurable pressure-sensitive adhesive composition contains an ultraviolet absorber, the reason for the increase in the peeling force of the release film on the light-irradiated surface side is not clear, but the reaction of the unreacted reactive functional group in the release layer with the compound in the pressure-sensitive adhesive composition is involved. It is presumed that there is

As mentioned above, most of the ultraviolet light irradiated to the photocurable adhesive composition containing a ultraviolet absorber is absorbed by a ultraviolet absorber. When the ultraviolet absorber absorbs light, the light energy is converted into thermal energy and the temperature rises. In particular, in the vicinity of the interface between the release layer of the release film on the side of the light irradiated surface and the pressure-sensitive adhesive composition layer, since the amount of light absorbed by the ultraviolet absorber is large, the temperature tends to rise. When temperature rises under light irradiation, it will become easy to advance thermosetting reaction in addition to photocuring reaction. Therefore, it is thought that the adhesive force (peel force) rises by reaction etc. of the unreacted heat-reactive functional group in the release layer 15 and the compound in an adhesive composition.

As shown in the reference example mentioned later, the release film whose peeling force rose by photocuring of an adhesive is once peeled from an adhesive sheet (the peeling strength at this time is called 1st peeling strength F1), The same or the same type of release film When a peel test is performed by bonding to an adhesive sheet again (the peeling strength at this time is called 2nd peeling strength F2), 2nd peeling strength F2 will become small compared with 1st peeling strength F1. Also from this, formation of a chemical bond at the time of photocuring, etc. are considered to be the cause which the adhesive force of a mold release layer and an adhesive layer becomes large.

Since the condensed silicone resin constituting the condensed silicone release layer has few or no functional groups with high thermal reactivity such as an alkenyl group, even when the temperature rises due to light absorption by the ultraviolet absorber during photocuring, It is hard to generate|occur|produce reaction of the compound in the adhesive composition layer 55, and the functional group in the mold release layer 15, and it is thought that the excessive raise of peeling force can be suppressed.

Since the fluorine-based resin constituting the fluorine-based release layer has a small surface free energy, the interaction between the highly reactive functional group in the pressure-sensitive adhesive composition and the release layer is small, and the chemical reaction at the interface is difficult to occur. It is thought to be involved in suppression.

As mentioned above, 0.1-1N/50mm of 1st peeling strength F1 at the time of peeling the 1st release film 10 from the photocurable adhesive sheet 50 are preferable. It is preferable that the 2nd peeling strength F2 at the time of peeling the 1st release film 10 from the photocurable adhesive sheet 50 and bonding and peeling the release film of the same or the same kind again is smaller than F1. As for F1/F2, 3 or less are preferable. F1/F2 is generally 0.5 or more. 0.7-2.5 are more preferable, and, as for F1/F2, 0.8-2.0 are still more preferable.

[Use of the adhesive sheet]

Since said photocurable adhesive sheet has a high visible light transmittance|permeability and also has ultraviolet-blocking property, it is used suitably as an optical adhesive for display devices or display input devices which are requested|required of ultraviolet-ray blocking property. Examples of the display device include a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), and electronic paper. A touch panel is mentioned as an input device. Moreover, the said photocurable adhesive sheet can also be used for bonding of a display device and an input device, bonding with the transparent plate arrange|positioned on the surface of a display device or an input device, etc.

When using a pressure-sensitive adhesive sheet having a release film having a release film temporarily attached to both sides, first peel the light release film (the second release film 20) to expose the second main surface of the pressure-sensitive adhesive sheet 50, 1 Bonding with an adherend is performed. Then, the heavy peeling film (1st release film 10) is peeled, the 1st main surface of the adhesive sheet 50 is exposed, and bonding with a 2nd to-be-adhered body is performed. After peeling the release film on both surfaces, you may bond with a to-be-adhered body. When the pressure-sensitive adhesive sheet has photocurability, the pressure-sensitive adhesive sheet after bonding with the adherend may be further irradiated with light. By further photocuring the pressure-sensitive adhesive sheet after bonding with the adherend, the adhesion reliability with the adherend can be improved in some cases.

Example

The present invention will be described in more detail below by way of Examples and Comparative Examples, but the present invention is not limited to these Examples.

[Preparation of adhesive composition]

In a monomer mixture consisting of 2-ethylhexyl acrylate (2EHA): 78 parts by weight, N-vinyl-2-pyrrolidone (NVP): 18 parts by weight, and 2-hydroxyethyl acrylate (HEA): 4 parts by weight, As a photoinitiator, 1-hydroxycyclohexylphenyl ketone ("Irgacure 184" manufactured by BASF): 0.035 parts by weight, and 2,2-dimethoxy-1,2-diphenylethan-1-one (manufactured by BASF " Irgacure 651"): 0.035 parts by weight was added. The composition was irradiated with ultraviolet rays to perform prepolymerization until the viscosity at room temperature reached about 20 Pa·s to obtain a prepolymer having a polymerization rate of about 8%.

To 100 parts by weight of the prepolymer composition, polyester urethane diacrylate having a weight average molecular weight of 12500 (“Art Resin UN-350” manufactured by Negami Kogyo Co., Ltd.): 2 parts by weight, acrylic oligomer: 5 parts by weight, UV absorber (“Tinosorb manufactured by BASF”): S"): 0.70 parts by weight, as a photopolymerization initiator, "Irgacure 184" manufactured by BASF: 0.05 parts by weight, "Irgacure 651" manufactured by BASF: 0.05 parts by weight, and "Irgacure 819" manufactured by BASF: 0.40 weight parts, α-methylstyrene dimer (“Nopmer MSD” manufactured by Nichi Oil Corporation): 0.07 parts by weight as a chain transfer agent, and “KBM-403” manufactured by Shin-Etsu Chemical as a silane coupling agent: 0.3 parts by weight After adding, these are uniformly It mixed to prepare a photocurable adhesive composition. As the acrylic oligomer, an oligomer having a weight average molecular weight of 5100 having dicyclopentanyl methacrylate and methyl methacrylate (MMA) in a weight ratio of 60:40 as a monomer component was used.

[Production of release film A]

A fluorine-free addition type silicone composition containing a polyorganosiloxane having a hexenyl group (“LTC761” manufactured by Toray Dow Corning): 30 parts by weight, silicone dispersion (“BY 24-850” manufactured by Toray Dow Corning): 0.9 weight and platinum catalyst for silicone curing (“SRX 212” manufactured by Toray Dow Corning): 2 parts by weight was diluted with a mixed solvent of toluene and hexane at a volume ratio of 1:1 to prepare a mold release agent solution. This solution was applied to one side of a biaxially stretched polyester film having a thickness of 75 μm, heated with a hot air dryer at 130° C. for 1 minute, and a release film A having a fluorine-free addition type silicone release layer on one side of the polyester film was produced.

[Comparative Example 1]

In Comparative Example 1, the above release film A was used for each of the support release film and the cover release film. The adhesive composition was apply|coated to the release layer formation surface of the support release film to a thickness of 300 micrometers, the application layer was formed, the cover release film was bonded to the surface of the application layer, and the laminated body was obtained. This laminate is photocured by irradiating ultraviolet rays with a black light positioned so that the irradiation intensity on the irradiated surface just below the lamp is 5 mW/cm ² from the cover release film side, and photocuring is performed, and a photocurable pressure-sensitive adhesive layer A pressure-sensitive adhesive sheet having a release film on both surfaces was obtained.

[Example 1]

As the cover release film, instead of the release film A, a release film having a fluorine-based addition type silicone release layer on one side of the polyester film (“FSC6” manufactured by Nipper) was used. Other than that, it carried out similarly to the comparative example 1, and obtained the adhesive sheet which has a release film on both surfaces of a photocurable adhesive layer.

[Example 2]

As the cover release film, instead of the release film A, a release film (“SR(S)” manufactured by Nipper) having a non-fluorine-containing condensed silicone release layer on one side of the polyester film was used. Other than that, it carried out similarly to the comparative example 1, and obtained the adhesive sheet which has a release film on both surfaces of a photocurable adhesive layer.

[Reference Example 1]

In Comparative Example 1 and Examples 1 and 2, ultraviolet irradiation was performed from the opposite side, that is, from the support release film side, the coating layer was cured, and a pressure-sensitive adhesive sheet having a release film on both surfaces of the photocurable pressure-sensitive adhesive layer was obtained.

[Peelability evaluation]

<Peel strength of release film>

A pressure-sensitive adhesive sheet having a release film is cut to a width of 50 mm, and a 180° peel test is performed at a tensile speed of 0.3 m/min using a tensile tester in an environment of 23° C., when peeling the cover release film from the pressure-sensitive adhesive sheet The peel strength of the was measured. That is, about the sample of Comparative Example 1 and Examples 1 and 2, the peeling strength of the release film on the side of a light irradiation surface, and the peeling strength of the release film of the surface opposite to the light irradiation surface about Reference Example 1 was measured.

[Evaluation results]

Table 1 shows the measurement results of the types of the cover release films of Examples and Comparative Examples and the peel strength of the cover release films.

When photocuring of an adhesive by light irradiation from the side of a support release film (Reference Example 1), even if any release film was used, the special difference was not seen in the peeling strength of a cover release film. When light irradiation was performed from the cover release film side, in Comparative Example 1, the peeling strength exceeded 1N/50mm, and the significant increase of the peeling strength was seen. On the other hand, in Example 1 using a fluorine-based silicone release film and Example 2 using a condensed silicone release film, although the peeling strength increased compared with Reference Example 1, the peeling strength was less than 0.5N/50mm.

[Reference Example 2]

From the pressure-sensitive adhesive sheet provided with the release film of Comparative Example 1 (an example in which a non-fluorine-based addition type silicone release film was used as the cover release film), the support release film (light release film) was peeled, and the pressure-sensitive adhesive sheet was bonded to a glass plate. The cover release film (middle release film) was peeled off from this sample, the release film of the same type was bonded to the adhesive sheet, and it pressurized with a hand roller. It was 0.20 N/50 mm when the notch of width 5cm was put in the release film and the peeling strength was measured.

From the comparison between Comparative Example 1 and Reference Example 1 and Reference Example 2, in Comparative Example 1, the action of increasing the adhesive force between the release layer and the pressure-sensitive adhesive layer by light irradiation at the time of curing the pressure-sensitive adhesive composition (for example, a release agent) Since the production|generation of the chemical bond by reaction of the resin component of and the hardening component in an adhesive, etc.) was large, it is thought that the peeling strength rose.

On the other hand, in Examples 1 and 2, the residual amount of curing-reactive functional groups in the resin material constituting the release layer is small, and in Example 1, since the surface free energy of the release layer is small due to the introduction of fluorine, the release layer It is thought that the adhesive force synergistic effect by generation|generation etc. of the chemical bond between and an adhesive layer was small, and the excessive raise of peeling strength was suppressed.

1: Adhesive sheet with release film
10, 20: release film
11, 21: film substrate
15, 25: release layer

Claims (10)

a photocurable pressure-sensitive adhesive sheet having a first main surface and a second main surface; a first release film temporarily attached to the first main surface of the pressure-sensitive adhesive sheet; And a pressure-sensitive adhesive sheet having a release film having a second release film temporarily attached to the second main surface of the pressure-sensitive adhesive sheet,
The first release film is provided with a first release layer on the first film substrate,
The second release film is provided with a second release layer on the second film substrate,
Each of the first release layer and the second release layer is in contact with the pressure-sensitive adhesive sheet,
The pressure-sensitive adhesive sheet includes a photocurable acrylic polymer and a UV absorber,
The said 1st release layer is a fluorine-type release layer or a condensed silicone release layer, The adhesive sheet provided with the release film. According to claim 1,
The peeling strength at the time of peeling a said 1st release film from the said adhesive sheet calculated|required by the 180 degree peel test with a peeling rate of 0.3 m/min is 0.1-1N/50mm, The adhesive sheet provided with a release film. 3. The method of claim 1 or 2,
1st peeling strength F1 which is the peeling strength at the time of peeling the said 1st release film from the said adhesive sheet,
Peeling strength when peeling the 1st release film from the sample which peels the said 1st release film from the said adhesive sheet, and has joined so that the 1st release layer of the said 1st release film may contact with the said adhesive sheet again, 2nd Peel strength F2,
The adhesive sheet provided with the release film which satisfy|fills F1/F2≤3. 4. The method according to any one of claims 1 to 3,
The adhesive sheet provided with the release film in which the peeling strength from the said adhesive sheet of a said 1st release film is larger than the peeling strength from the said adhesive sheet of a said 2nd release film. 5. The method according to any one of claims 1 to 4,
The adhesive sheet provided with the release film in which the said photocurable acrylic polymer contains the polyfunctional monomer which has two or more polymerizable functional groups in 1 molecule as a copolymerization monomer component. 6. The method according to any one of claims 1 to 5,
The said adhesive sheet is an adhesive sheet provided with the release film whose light transmittance of wavelength 380nm is 50 % or less. 7. The method according to any one of claims 1 to 6,
The pressure-sensitive adhesive sheet, with respect to 100 parts by weight of the acrylic polymer, containing 0.1 to 10 parts by weight of the ultraviolet absorber, the pressure-sensitive adhesive sheet provided with a release film. 8. The method according to any one of claims 1 to 7,
The said 2nd release layer is a non-fluorine-type addition type silicone release layer, The adhesive sheet provided with the release film. a photocurable pressure-sensitive adhesive sheet having a first main surface and a second main surface; a first release film temporarily attached to the first main surface of the pressure-sensitive adhesive sheet; And a method for producing a pressure-sensitive adhesive sheet having a release film having a second release film temporarily attached to the second main surface of the pressure-sensitive adhesive sheet,
A photocurable pressure-sensitive adhesive composition comprising an acrylic monomer and/or a partial polymer of an acrylic monomer, an ultraviolet absorber, and a photopolymerization initiator is provided in a layered manner between the first release film and the second release film to form a laminate; and
A step of photocuring the photocurable pressure-sensitive adhesive composition by irradiating light from the side of the first release film to the photocurable pressure-sensitive adhesive composition between the first release film and the second release film;
The first release film includes a first release layer on the surface of the film substrate on the side in contact with the photocurable pressure-sensitive adhesive composition,
The second release film is provided with a second release layer on the surface of the film substrate on the side in contact with the photocurable pressure-sensitive adhesive composition,
The manufacturing method of the adhesive sheet provided with the release film whose said 1st mold release layer is a fluorine-type mold release layer or a condensation-type silicone mold release layer. 10. The method of claim 9,
The method for producing a pressure-sensitive adhesive sheet provided with a release film, wherein the second release layer is a non-fluorine-based addition type silicone release layer.

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