JP2003253225A - Method for producing adhesive film and liquid composition for adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an adhesive film, with which sufficient thickening is simply obtained at a low cost in excellent reproducibility and the properties of the adhesive after the photopolymerization are not substantially influenced in the production of an adhesive film by adding a photopolymerization initiator to a vinyl-based monomer consisting essentially of a (meth)acrylic acid alkyl ester, irradiating the vinyl-based monomer with ultraviolet light and photopolymerizing the monomer and to obtain a liquid composition for an adhesive useful for the production. <P>SOLUTION: The method for producing the adhesive film comprises coating a peelable carrier or a substrate for a film with the liquid composition for an adhesive comprising the vinyl-based monomer consisting essentially of the (meth)acrylic acid alkyl ester, hydrophilic silica, an alkylene glycol polymer and a photopolymerization initiator and irradiating the composition with ultraviolet light to polymerize the vinyl- based monomer. The liquid composition for an adhesive, useful for the method for producing the adhesive film comprises the vinyl-based monomer consisting essentially of a (meth)acrylic acid alkyl ester, hydrophilic silica, an alkylene glycol polymer and a photopolymerization initiator. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an acrylic pressure-sensitive adhesive film, and a liquid composition for pressure-sensitive adhesive used in the production method. The adhesive film in the present invention includes an adhesive sheet, an adhesive tape and the like.

[0002]

2. Description of the Related Art Acrylic adhesive films have excellent adhesive properties such as adhesive strength and cohesive strength, and aging resistance such as weather resistance and heat resistance, and are particularly permanent bonding of various structural members such as automobiles, electric products and buildings. It is also used as a material. The pressure-sensitive adhesive that constitutes the acrylic pressure-sensitive adhesive film is often produced by solution polymerization, emulsion polymerization, or bulk polymerization. In addition, a production method in which ultraviolet rays are used to perform polymerization without a solvent has been drawing attention.

In the production method of polymerizing an acrylic pressure-sensitive adhesive by irradiation with ultraviolet rays, since the viscosity of the liquid composition for an acrylic pressure-sensitive adhesive to be polymerized is low and it is difficult to handle, various methods of increasing the viscosity have been used. . For example Tokuhei 07-0
78202 discloses a method of adding acrylic rubber or epichlorohydrin rubber as a thickening agent, a method of adding colloidal silica as a thixotropic agent, or a method of preliminarily polymerizing a part of a vinyl monomer by irradiating a small amount of ultraviolet rays. Have been described.

[0004]

However, the above thickening method has a problem that the thickening effect is low and the manufacturing process is complicated and the cost is high. The method of adding rubber as a thickener usually requires that the amount of rubber be 5 parts or more with respect to 100 parts by weight of the acrylic monomer in order to increase the viscosity to an appropriate level. This is a problem because it greatly affects the adhesive properties after photopolymerization. In addition, the method of adding hydrophilic silica (colloidal silica) as a thixotropic agent can easily increase the viscosity at low cost, but the hydrophilic silica alone does not sufficiently increase the viscosity, or exceeds a certain amount. When added, the flexibility of the pressure-sensitive adhesive was impaired and there was a problem in the adhesiveness to the rough surface. Further, in the method of partially polymerizing the vinyl-based monomer in advance, the polymer adheres to the light irradiation site in the polymerization kettle or the dispersion of the polymerization reaction is large, and the reproducibility of the molecular weight and the polymerization conversion rate of the polymer is difficult. is there. Further, there is a problem in that even when the polymerization is partially carried out by heating, there are large variations in the polymerization reaction, or it is difficult to control the cooling of the polymerization heat because no solvent is contained.

The present invention is a simple and inexpensive method for producing a pressure-sensitive adhesive film by adding a photopolymerization initiator to a vinyl monomer containing a (meth) acrylic acid alkyl ester as a main component, irradiating it with ultraviolet rays and photopolymerizing it. Provided is a method for producing a pressure-sensitive adhesive film capable of obtaining sufficient thickening with good reproducibility and substantially not affecting characteristics of the pressure-sensitive adhesive after photopolymerization, and a liquid composition for pressure-sensitive adhesive used in the production. The purpose is to do.

[0006]

In order to achieve the above object, the present invention according to claim 1 provides a vinyl-based monomer having a (meth) acrylic acid alkyl ester as a main component, a hydrophilic silica, and an alkylene glycol polymer. And a pressure-sensitive adhesive film characterized by applying a liquid composition for pressure-sensitive adhesive containing a photopolymerization initiator to a releasable carrier or a substrate for film, and then irradiating ultraviolet rays to polymerize the vinyl-based monomer. A method for manufacturing the same is provided. Further, the present invention according to claim 2 provides the method for producing an adhesive film according to claim 1, wherein the liquid composition for pressure-sensitive adhesive further contains an isocyanate crosslinking agent. Further, the present invention according to claim 3 provides 100 parts by weight of a vinyl-based monomer containing an alkyl (meth) acrylate as a main component, 0.5 to 5 parts by weight of hydrophilic silica, and an alkylene glycol polymer of 0.0
003 to 3 parts by weight and 0.01 to 5 parts by weight of a photopolymerization initiator, a liquid composition for pressure-sensitive adhesive is applied to a releasable carrier or a substrate for a film or a substrate for a film, and then an ultraviolet ray is applied. Provided is a method for producing an adhesive film, which comprises irradiating and polymerizing the vinyl-based monomer. Further, the present invention according to claim 4 is 100 parts by weight of a vinyl-based monomer containing (meth) acrylic acid alkyl ester as a main component,
Hydrophilic silica 0.5 to 5 parts by weight, alkylene glycol polymer 0.0001 to 3 parts by weight, photopolymerization initiator 0.01
To 5 parts by weight and 0.01 to 3 parts by weight of an isocyanate-based cross-linking agent are applied to a release film or a substrate for a film, and then irradiated with ultraviolet rays to obtain the vinyl-based composition. Provided is a method for producing an adhesive film, which comprises polymerizing a monomer. Further, the present invention according to claim 5 is characterized by containing a vinyl-based monomer containing a (meth) acrylic acid alkyl ester as a main component, hydrophilic silica, an alkylene glycol polymer and a photopolymerization initiator. A liquid composition for pressure-sensitive adhesive used in the method for producing a pressure-sensitive adhesive film according to claim 1. Further, the present invention according to claim 6 is such that 100 parts by weight of a vinyl-based monomer containing an alkyl (meth) acrylate as a main component, 0.5 to 5 parts by weight of hydrophilic silica, and an alkylene glycol polymer of 0.0001 to 3 Parts by weight, 0.01 to 5 parts by weight of a photopolymerization initiator and 0.0 as an isocyanate cross-linking agent.
The liquid composition for pressure-sensitive adhesive used in the method for producing a pressure-sensitive adhesive film according to claim 4, wherein the liquid composition contains 1 to 3 parts by weight.

The present invention will be described in more detail below. In order to obtain the pressure-sensitive adhesive film according to the present invention, for example, first, a liquid composition for pressure-sensitive adhesive containing the above vinyl-based monomer is prepared.

The vinyl-based monomer containing a (meth) acrylic acid alkyl ester as a main component in the present invention is generally (meth) acrylic acid alkyl ester 100 to 60.
% By weight and other vinyl-based monomer copolymerizable therewith 0
~ 40% by weight. And, as the (meth) acrylic acid alkyl ester, the carbon number of the alkyl group is 1 to 1.
4, preferably 4 to 12 (meth) acrylic acid acrylic ester is used, and examples thereof include n-butyl (meth) acrylic acid, 2-ethylhexyl (meth) acrylic acid, isooctyl (meth) acrylic acid, and (meth) acrylic acid. Isononyl acid and the like are preferably used.

Other vinyl monomers copolymerizable with the above (meth) acrylic acid ester are generally acrylic acid, methacrylic acid, acrylamide, acrylonitrile, N-substituted acrylamide, hydroxydiethyl acrylate, N. -Vinylpyrrolidone, maleic acid, itaconic acid, N-methylol acrylamide, hydroxyethyl methacrylate, ethylene glycol monoacrylate, glycerin monoacrylate, etc. are used.

In addition, an olefin polymer having a polymerizable unsaturated double bond at the terminal can also be used. The compound is not particularly limited as long as it has a double bond which is copolymerizable with another polymerizable monomer at the terminal and a polymer structure composed of a polyolefin main skeleton. Specific examples of the polyolefin skeleton include an ethylene-butylene copolymer, an ethylene-propylene copolymer, an ethylene copolymer and a butylene copolymer. Commercially available ethylene-butylene copolymers include, for example, Kraton.
"Clayton Liquid Polymer L-1251" and "Clayton Liquid Polymer L-1253" manufactured by Polymer Japan Co., Ltd. may be mentioned.

As the photopolymerization initiator, for example, 4-
(2-Hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone [Brand name: Darocur 295
9, manufactured by Merck & Co., Inc .; α-hydroxy-
α, α'-dimethyl-acetophenone [trade name: Darocur 1173, manufactured by Merck], methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophen [trade name: Irgacure 651, manufactured by Ciba Geigy],
Acetophenone-based compounds such as 2-hydroxy-2-cyclohexylacetophenone [trade name: Irgacure 184, manufactured by Ciba Geigy]; ketal-based compounds such as benzyl dimethyl ketal; . The amount of the photopolymerization initiator added is usually 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the vinyl-based monomer. When the amount of the photoinitiator added is less than 0.01 part by weight, the polymerization conversion rate is lowered and only a polymer having a strong monomer odor can be obtained. If it exceeds 5 parts by weight, the amount of radicals generated increases and the molecular weight decreases, so that the necessary cohesive force cannot be obtained.

As the hydrophilic silica in the present invention, hydrophilic fine particle silica having a hydrophilic group (silanol group) on the surface is used. Generally, 0.5 to 5 parts by weight of hydrophilic silica is added to 100 parts by weight of the vinyl-based monomer. If the hydrophilic silica is 0.5 parts by weight or less, the thickening effect is insufficient, and if it is 5 parts by weight or more, the flexibility of the pressure-sensitive adhesive is impaired, causing a problem in adhesiveness to a rough surface. The amount of hydrophilic silica added is preferably 1.5 to 3.5 parts by weight.

The alkylene glycol polymer in the present invention includes those referred to as poly (oxyalkylene) glycol, polyoxyalkylene ether and polyalkylene oxide, and the polymer main chain has a polyether structure. . Polyethylene glycol, polypropylene glycol, polytrimethylene glycol,
Examples thereof include homopolymers such as polytetramethylene glycol and polyethers such as copolymers such as oxyethylene-oxypropylene copolymer. The alkylene glycol polymer is usually added in an amount of 0.0001 to 3 parts by weight with respect to 100 parts by weight of the vinyl-based monomer. When the amount of the alkylene glycol polymer is less than 0.0001 parts by weight, the thickening effect is insufficient, and when it is 3 parts by weight or more, the adhesive properties may be adversely affected. The addition amount of the alkylene glycol polymer is preferably 0.0003 to 0.01 part by weight. As for the molecular weight of the alkylene glycol polymer, the larger the molecular weight, the greater the effect of thickening. As for the molecular weight, an average molecular weight of 30,000 or more has a large effect of thickening, and is preferably 100,000 to 4,000,000.

In the present invention, a small amount of a polyfunctional (meth) acrylate compound is added together with the vinyl-based monomer, the photopolymerization initiator, the hydrophilic silica and the alkylene glycol polymer to simultaneously polymerize the acrylic copolymer. Crosslinking may be performed. As the polyfunctional (meth) acrylate compound, for example, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol (meth) acrylate, ( Poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, glycerin methacrylate acrylate, pentaerythritol tri (meth) acrylate, Trimethylol propane trimethacrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy (meth) acrylate, polyester (meth) acrylate, urethane (meth) acryl Rate and the like, even if they are used alone,
You may use together 2 or more types. The addition amount of the polyfunctional (meth) acrylate compound is 0 to 5 parts by weight with respect to 100 parts by weight of the vinyl-based monomer (usually a liquid).

Further, in the present invention, crosslinking can be carried out by adding a small amount of an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent or the like as a crosslinking agent to the vinyl monomer. As a cross-linking agent,
For example, tolylene diisocyanate, naphthylene-1,
Isocyanate crosslinking agents such as 5-diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, trimethylolpropane modified tolylene diisocyanate, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,6-hexanediol glycidyl Epoxy cross-linking agent such as ether, N, N-hexamethylene-1,6-
Examples include aziridine crosslinking agents such as bis (1-aziridinecarboxamide). These may be used alone or in combination of two or more. Other examples include trifunctional isocyanate compounds and trifunctional epoxy compounds. Examples of trifunctional isocyanate compounds include triphenylmethane triisocyanate, tolylene diisocyanate, adducts of these trimethylolpropanes, and buret-bonded compounds. Three
Examples of functional epoxy compounds include diethylenetriamine and trimethylolpropane adducts of triglycidyl ether. These can be used alone,
Two or more kinds may be used in combination. Isocyanate crosslinking agent,
The addition amount of the epoxy-based crosslinking agent and the aziridine-based crosslinking agent is 0 to 100 parts by weight of the vinyl-based monomer liquid material.
It is in the range of 5 parts by weight. In particular, when the isocyanate crosslinking agent is added, the addition amount is preferably in the range of 0.01 to 3 parts by weight with respect to 100 parts by weight of the vinyl monomer liquid material.

In the present invention, a tackifying resin can be added as appropriate. When the tackifying resin is added to the photopolymerizable composition and polymerized, the polymerization rate may be lowered or the molecular weight may be lowered. In that case, hydrogenation is generally performed. Examples of the tackifier having a low polymerization inhibitory property include hydrogenated terpene resin, hydrogenated rosin, disproportionated rosin resin and hydrogenated petroleum resin.

Various additives may be added to the vinyl monomer in the present invention. Examples of the additives include plasticizers, softeners, inorganic fillers (calcium carbonate, talc, aluminum oxide, silica, etc.),
Examples include organic fillers, pigments and dyes. In addition, the volume of the pressure-sensitive adhesive composition may be increased by adding hollow particles having an average particle diameter of 5 to 200 μm as a filler, adding a foaming agent, or performing polymerization while stirring and mixing a gas with a copolymerization component before polymerization. May be increased.

To produce the pressure-sensitive adhesive film according to the present invention, for example, a vinyl-based monomer containing a (meth) acrylic acid alkyl ester as a main component is mixed with hydrophilic silica and then dispersed and mixed by using a high-speed stirrer. Photopolymerization initiator,
It is necessary that the viscosity of the liquid material containing the alkylene glycol polymer, various additives and the like be increased to a coatable viscosity. The viscosity suitable for coating is 1.5 to 15 Pa · S. The coating apparatus is appropriately selected, but the roll coater is used first. In this case, when the viscosity is low, the pressure-sensitive adhesive may leak from the weir in the coating portion, or the pressure-sensitive adhesive may flow after the coating and before the polymerization, resulting in a non-uniform thickness. On the other hand, when the viscosity is high, there are problems that streaks are generated on the coated surface and bubbles are easily mixed.

The liquid composition for pressure-sensitive adhesive is generally purged with an inert gas such as nitrogen gas in order to remove dissolved oxygen. The liquid substance purged with the inert gas is applied and coated on the releasable carrier or the film substrate in an inert gas atmosphere, and then irradiated with ultraviolet rays. Examples of the releasable carrier include release papers, release-treated plastic films, metal foils, etc., but these are limited to layered materials as long as they can be peeled off after coating and coating. is not.
Examples of the film substrate include cloth, non-woven fabric, and paper, which are used as they are without peeling off the film-shaped pressure-sensitive adhesive, that is, the pressure-sensitive adhesive film, after the liquid composition is applied or impregnated and polymerized. Irradiation with ultraviolet rays is in a state of being shielded from oxygen under an inert gas atmosphere or by coating the liquid composition for pressure-sensitive adhesive with a plastic film, regardless of whether the release carrier or the film substrate is used. Done in.

As lamps used for light irradiation in photopolymerization, those having a light emission distribution at a light wavelength of 400 nm or less are used, and examples thereof include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, and a chemical lamp. , Black light lamps, microwave-excited mercury lamps, metal halide lamps and the like are used. Among them, the chemical lamp efficiently emits light in the active wavelength region of the initiator and the light absorption of the composition other than the initiator is small, so that the light is transmitted to the inside and is preferable for manufacturing a high-thickness product. . The light irradiation intensity of the photopolymer composition by the lamp is a factor that influences the degree of polymerization of the obtained polymer, and is appropriately controlled for each performance of the target product, but it is a cleavage type having an ordinary acetophenone group. When an initiator is added,
The light intensity in the range is preferably 0.1 to 100 mW / cm <2> in the wavelength region effective for photodecomposition of the initiator (it varies depending on the initiator, but light of 365 nm to 420 nm is usually used).

The pressure-sensitive adhesive composition obtained by the present invention may be used as a pressure-sensitive adhesive as it is, or may be used in the form of a pressure-sensitive adhesive film. When the pressure-sensitive adhesive film is used, it may be in the form of a double-sided tape having no substrate, or may be a pressure-sensitive adhesive film with a substrate formed by forming an adhesive layer on one side or both sides of the substrate.

(Function) The mechanism of thickening which is made possible by adding hydrophilic silica to a vinyl monomer containing (meth) acrylic acid alkyl ester as a main component is as follows.
It is considered that the silanol groups on the surface of the hydrophilic silica are involved, and although the thickening effect of the acrylic monomer is recognized on the hydrophilic silica, it is not sufficient. On the other hand, in designing an acrylic pressure-sensitive adhesive, an isocyanate-based cross-linking agent is widely used as a cross-linking agent in order to balance the physical properties of the pressure-sensitive adhesive. However, since the isocyanate cross-linking agent reacts with water, if a certain amount of water is present in the reaction system, a problem occurs in which the acrylic polymer is not sufficiently cross-linked by the isocyanate. That is, since the hydrophilic silica is hydrated, the amount of the hydrophilic silica used is limited when the isocyanate cross-linking agent is used.

In the present invention, when the hydrophilic silica is added to the vinyl-based monomer to increase the viscosity, the addition of the alkylene glycol polymer achieves sufficient viscosity even when the water content in the reaction system is low. This makes it possible to use an isocyanate-based cross-linking agent, which is preferable for achieving the balance of adhesive properties. After all, by using hydrophilic silica and an alkylene glycol polymer in combination, the thickening effect can be remarkably enhanced, and a liquid composition for pressure-sensitive adhesive having a viscosity suitable for the coating step can be obtained, and at the same time, in the final polymer, It is possible to obtain good adhesive physical properties without any impediment to crosslinking of isocyanate due to water contained in the hydrophilic silica and no adverse effect on the adhesive as seen when adding acrylic rubber.

[0024]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples.

(Evaluation Method) Evaluation methods for the adhesive films in Examples and Comparative Examples are as follows. (1) 90 Degree Peel Adhesion Test Polyethylene terephthalate (PE) with release treatment applied to both front and back surfaces of an adhesive layer in an atmosphere of 23 ° C. and 65% RH
T) A pressure-sensitive adhesive film coated with a film is cut into a width of 25 mm and a length of 100 mm, one release PET film is peeled off, and the exposed pressure-sensitive adhesive surface has a width of 50 mm and a length of 150 mm.
It was attached to a stainless steel plate (made by Nippon Test Panel Co., Ltd.) such that the adhesion length was 100 mm. Next, the other release PET film of the above-mentioned adhesive film was peeled off, and a polyester film having a thickness of 25 μm was attached to the exposed adhesive surface as a backing material. After reciprocating and crimping, 23
After standing at 65 ° C RH for 24 hours, the 90-degree peel adhesion was measured at a pulling speed of 300 mm / min using a tensile tester under an atmosphere of 23 ° C.

(2) Shear Adhesion Test A pressure-sensitive adhesive film obtained by coating both sides of the pressure-sensitive adhesive layer with a release PET film was cut into a width of 25 mm and a length of 25 mm, and 23
In a RH 65% RH atmosphere, two stainless steel plates (made by Nippon Test Panel Co., Ltd.) having a width of 50 mm and a length of 100 mm are bonded to each other with an adhesive film from which release PET films on both sides are peeled off, and a load of 5 kg is applied. After 15 minutes of pressure bonding, it was pulled in the shear direction at a pulling speed of 50 m / min after 24 hours, and the shear adhesive strength was measured.

(3) Holding power test In an atmosphere of 23 ° C. and 65% RH, a pressure-sensitive adhesive film in which both sides of the pressure-sensitive adhesive layer are coated with a release PET film has a width of 2
Cut to 5 mm and length 25 mm, peel off one release PET film to expose the adhesive surface, width 50 mm, length 5
It was attached to a 0 mm stainless plate (manufactured by Nippon Test Panel Co., Ltd.). Next, the other release PET film of the pressure-sensitive adhesive film was peeled off, and a 1.3 mm-thick stainless steel plate was attached to the exposed pressure-sensitive adhesive surface. After pressing the stainless steel plate back and forth twice with a roller weighing 2 kg, 23
After leaving it at 65 ° C RH for 24 hours, it was left in a gear oven at 80 ° C for 1 hour. Then, a weight of 1 kg was attached to the stainless steel plate in a gear oven at 80 ° C., and the time until it dropped was measured.

(4) The object of viscosity measurement was allowed to stand for 1 day at room temperature and then measured. Using a B-type rotational viscometer, the viscosity was measured at NO. 3 and rotation speed of 6 rpm.

(5) Coating suitability

(Example 1) 80 parts by weight of 2-ethylhexyl acrylate, 20 parts by weight of n-butyl acrylate, 5 parts by weight of acrylic acid, hydrophilic silica (Aerosil A-20)
0: Nippon Aerosil Co., Ltd.) 3 parts by weight, and polyethylene glycol 70,000 (average molecular weight 70,000, Wako Pure Chemical Industries, Ltd.) 1 part by weight are added, and the mixture is stirred with a high-speed stirrer (Homo Disper) to uniformly mix and thicken. Further, a polymerization initiator (IRGACURE-6
51, Ciba Geigy) 0.1 part by weight and 0.15 part by weight of 1,6 hexanediol diacrylate are added and mixed uniformly, and this is purged with nitrogen gas to remove dissolved oxygen to form a liquid substance. It was adjusted. Then, release treatment 50
A spacer having a thickness of 0.5 mm is placed on a polyethylene terephthalate (PET) film having a thickness of μm, the polymerizable monomer solution is spread on a PET film subjected to a mold release treatment, and then the PET film is bent to give a mold release treated surface. Was in contact with the polymerizable monomer solution. In this state, the lamp intensity of the chemical lamp was adjusted so that the UV irradiation intensity on the PET film on the coated side was 10 mW / cm ^2, and the film was exposed to UV rays for 10 minutes to obtain a film-like pressure-sensitive adhesive composition (hereinafter referred to as a pressure-sensitive adhesive film). Got

(Example 2) Polyethylene glycol 7000
An adhesive film was obtained in the same manner as in Example 1 except that 1 part by weight of poly (oxyethylene / oxypropylene) glycol (Newpol 75H-90000, number average molecular weight 15000, Sanyo Kasei Co., Ltd.) was added instead of 0. It was

Example 3 An olefin-based copolymer having a polymerizable unsaturated double bond at its end (trade name: HPVM-L)
1253, made by Kraton Polymer Japan Co., Ltd.) 12 parts by weight were added, and instead of polyethylene glycol 70000, polyethylene glycol 2000000 (molecular weight 2,000,000, Wako Pure Chemical Industries, Ltd.) 0.0008 parts by weight, tackifying resin (alicyclic saturated hydrocarbon resin) , Trade name: Alcon P-100, Arakawa Chemical Co., Ltd.) An adhesive film was obtained in the same manner as in Example 1 except that 20 parts by weight was added.

Example 4 0.1 part by weight of 2-hydroxyethyl methacrylate was added, and an isocyanate cross-linking agent (Coronate HX, Nippon Polyurethane Co., Ltd.) was used as a cross-linking agent instead of the polyfunctional acrylate 1,6 hexanediol diacrylate. An adhesive film was obtained in the same manner as in Example 3 except that 0.2 part by weight (solid content 100%) was added.

Comparative Example 1 Polyethylene glycol 2000
An adhesive film was obtained in the same manner as in Example 3 except that 000 was not added.

Comparative Example 2 An adhesive film was obtained in the same manner as in Example 3 except that hydrophilic silica was not added.

Table 1 shows the evaluation results of the examples and comparative examples.

[0037]

[Table 1]

[0038]

INDUSTRIAL APPLICABILITY The present invention relates to the viscosity of a liquid composition for a pressure-sensitive adhesive before photopolymerization when a pressure-sensitive adhesive is produced by photopolymerizing a vinyl-based monomer containing a (meth) acrylic acid alkyl ester as a main component. By using a hydrophilic silica and an alkylene glycol polymer, it is possible to increase the viscosity at low cost easily and with good reproducibility. Moreover, the polymer obtained by exposing the liquid composition for pressure-sensitive adhesive to ultraviolet rays does not impair the physical properties of the pressure-sensitive adhesive. By using this method, it is possible to obtain a pressure-sensitive adhesive film having a thick film pressure-sensitive adhesive layer at high speed and at low cost by taking advantage of the photopolymerization method.

Claims (6)

[Claims] 1. A releasable carrier comprising a liquid composition for pressure-sensitive adhesive, which comprises a vinyl-based monomer containing an alkyl (meth) acrylate as a main component, hydrophilic silica, an alkylene glycol polymer and a photopolymerization initiator. Alternatively, a method for producing a pressure-sensitive adhesive film, which comprises coating the substrate for a film and then irradiating it with ultraviolet rays to polymerize the vinyl-based monomer. 2. The liquid composition for pressure-sensitive adhesives, further comprising an isocyanate cross-linking agent.
A method for producing the adhesive film described. 3. 100 parts by weight of a vinyl-based monomer containing (meth) acrylic acid alkyl ester as a main component, 0.5 to 5 parts by weight of hydrophilic silica, 0.0001 to 3 parts by weight of an alkylene glycol polymer, and initiation of photopolymerization. Agent 0.01-5
A method for producing a pressure-sensitive adhesive film, which comprises applying a liquid composition for pressure-sensitive adhesive containing 1 part by weight to a releasable carrier or a film substrate, and then irradiating ultraviolet rays to polymerize the vinyl-based monomer. . 4. 100 parts by weight of a vinyl-based monomer containing (meth) acrylic acid alkyl ester as a main component, 0.5 to 5 parts by weight of hydrophilic silica, 0.0001 to 3 parts by weight of an alkylene glycol polymer, and initiation of photopolymerization. After applying a liquid composition for pressure-sensitive adhesive containing 0.01 to 5 parts by weight of an agent and 0.01 to 3 parts by weight of an isocyanate-based cross-linking agent to a base material for a releasable film, it is irradiated with ultraviolet rays. A method for producing an adhesive film, which comprises polymerizing the vinyl monomer. 5. The pressure-sensitive adhesive according to claim 1, which comprises a vinyl-based monomer containing a (meth) acrylic acid alkyl ester as a main component, hydrophilic silica, an alkylene glycol polymer and a photopolymerization initiator. A liquid composition for pressure-sensitive adhesive used in a method for producing a film. 6. A vinyl-based monomer containing (meth) acrylic acid alkyl ester as a main component 100 parts by weight, hydrophilic silica 0.5 to 5 parts by weight, alkylene glycol polymer 0.0001 to 3 parts by weight, photopolymerization initiation. The liquid composition for pressure-sensitive adhesives used in the method for producing a pressure-sensitive adhesive film according to claim 4, which comprises 0.01 to 5 parts by weight of the agent and 0.01 to 3 parts by weight of the isocyanate crosslinking agent.