JP2009001673A - Water-dispersed pressure-sensitive adhesive composition and pressure-sensitive adhesive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous dispersion self-adhesive composition having high adhesive properties with a glass substrate, and having high heat resistance and moisture resistance, an to provide a self-adhesive film with a self-adhesive layer composed of the aqueous dispersion self-adhesive composition. <P>SOLUTION: The aqueous dispersion self-adhesive composition is prepared by blending a crosslinking agent having an oxazoline group of 0.07 to 1.5 parts by weight per 100 parts by weight of an aqueous dispersion copolymer obtained by reacting a reaction component containing alkyl(meth)acrylate whose linear or branched alkyl group has 4 to 18 carbon atoms, (meth)acrylic acid, a phosphoric acid group-containing vinyl monomer and an alkoxysilyl group-containing vinyl monomer. One side of an optical film 1 is coated with the same, and heating and drying are performed, so as to form a self-adhesive layer 2, thus the self-adhesive optical film is obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a water-dispersed pressure-sensitive adhesive composition and a pressure-sensitive adhesive film.

Conventionally, optical films such as polarizing films, retardation films, brightness enhancement films, and viewing angle widening films have been used in various industrial applications, such as liquid crystal displays, organic electroluminescence devices (organic EL display devices), It is used by being attached to an image display device such as a plasma display panel (PDP).
As such an optical film, an adhesive optical film in which an adhesive is laminated on an optical film is known.

In recent years, from the viewpoint of environmental impact, it has been desired to reduce the use of organic solvents. From solvent-based adhesives that use organic solvents as solvents, to water-dispersed adhesives that use water as a dispersion medium. Conversion is desired.
As such a water-dispersed pressure-sensitive adhesive, for example, a pressure-sensitive adhesive composition containing a copolymer emulsion, wherein the copolymer is 10 to 50% by weight of methacrylic acid 2- A pressure-sensitive adhesive composition in which ethylhexyl is copolymerized and the glass transition temperature of the copolymer is −25 ° C. or lower has been proposed (for example, see Patent Document 1).
JP 2001-254063 A

However, the conventional water-dispersed pressure-sensitive adhesives including Patent Document 1 as described above have improved adhesion to hydrophobic adherends such as polyolefins, but have particularly good adhesion to hydrophilic adherends such as glass. It is low and it is difficult to firmly adhere to a glass substrate used in an image display device.
In addition, the water-dispersed pressure-sensitive adhesive layered on the optical film is required to have high heat resistance and moisture resistance that does not deteriorate the adhesiveness due to severe heating or humidification.

However, the above-mentioned water-dispersed pressure-sensitive adhesive has a problem that optical characteristics are deteriorated due to generation of bubbles and distortion due to severe heating or humidification.
An object of the present invention is a water-dispersed pressure-sensitive adhesive composition having high adhesion to a substrate and having high heat resistance and moisture resistance, and a pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer comprising the water-dispersed pressure-sensitive adhesive composition Is to provide.

  In order to achieve the above object, the water-dispersed pressure-sensitive adhesive composition of the present invention comprises (meth) acrylic acid alkyl ester having 4 to 18 carbon atoms and having a linear or branched alkyl group, (meth) Water-dispersed pressure-sensitive adhesive comprising a water-dispersed copolymer obtained by reacting a reaction component containing acrylic acid, a phosphoric acid group-containing vinyl monomer and an alkoxysilyl group-containing vinyl monomer, and a cross-linking agent having an oxazoline group It is a composition, The compounding ratio of the said crosslinking agent is 0.07-1.5 weight part with respect to 100 weight part of said water-dispersed copolymers, Adhesion which consists of said water-dispersed adhesive composition The agent layer is characterized in that the elongation at 90 ° C. according to the following test is 200% or less.

Test: A pressure-sensitive adhesive layer is prepared by heating a water-dispersed pressure-sensitive adhesive composition, and this is molded into a cylindrical shape having a cross-sectional area of 4.6 mm ² and a length of 30 mm to prepare a test piece. Then, the specimen was left for 1 hour at 90 ° C., to measure the length L ₀ of the initial specimen. Thereafter, one end of the test piece is fixed, a 12 g weight is attached to the other end of the test piece, the test piece is suspended at 90 ° C. for 2 hours, and the length L ₁ (mm) of the test piece after being suspended for 2 hours. And the elongation is calculated by the following formula.

Elongation (%) = (L ₁ −L ₀ ) / L ₀ × 100
In the water-dispersed pressure-sensitive adhesive composition of the present invention, it is preferable that the water-dispersed pressure-sensitive adhesive composition has a gel fraction of 80 to 95% by weight when immersed in ethyl acetate.
The pressure-sensitive adhesive film of the present invention is characterized by including a pressure-sensitive adhesive layer made of the water-dispersed pressure-sensitive adhesive composition described above.

The water-dispersed pressure-sensitive adhesive composition of the present invention and the pressure-sensitive adhesive film provided with a pressure-sensitive adhesive layer comprising the water-dispersed pressure-sensitive adhesive composition have high adhesive strength with the substrate and can achieve strong adhesion. . Furthermore, since it has high heat resistance and moisture resistance, excellent durability under a high temperature and high humidity atmosphere can be obtained.
In particular, the water-dispersed pressure-sensitive adhesive composition of the present invention and the pressure-sensitive adhesive film including the pressure-sensitive adhesive layer made of the water-dispersed pressure-sensitive adhesive composition effectively prevent the generation of bubbles and distortion at high temperatures and high humidity. be able to. Therefore, it is possible to effectively prevent a decrease in optical characteristics.

The water-dispersed pressure-sensitive adhesive composition of the present invention contains a water-dispersed copolymer and a crosslinking agent.
The water-dispersed copolymer can be obtained by reacting a reaction component containing (meth) acrylic acid alkyl ester, (meth) acrylic acid, a phosphoric acid group-containing vinyl monomer and an alkoxysilyl group-containing vinyl monomer.
The (meth) acrylic acid alkyl ester is a (meth) acrylic acid alkyl ester (methacrylic acid alkyl ester and / or acrylic acid alkyl ester) having 4 to 18 carbon atoms and having a linear or branched alkyl group. , For example, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, neopentyl (meth) acrylate, ( Isoamyl acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth) acrylic Acid nonyl, isononyl (meth) acrylate, decyl (meth) acrylate, ( T) Isodecyl acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, (meta ) Heptadecyl acrylate, octadecyl (meth) acrylate, and the like. Of these (meth) acrylic acid alkyl esters, butyl acrylate is preferable. These (meth) acrylic acid alkyl esters can be used alone or in combination.

The compounding ratio of the (meth) acrylic acid alkyl ester is, for example, 60 to 99 parts by weight, preferably 80 to 99 parts by weight, and more preferably 80 to 98 parts by weight with respect to 100 parts by weight of the reaction component.
Examples of (meth) acrylic acid include methacrylic acid and acrylic acid.
(Meth) acrylic acid can be used alone or in combination. The blending ratio of (meth) acrylic acid is, for example, 0.5 to 15 parts by weight, preferably 0.5 to 10 parts by weight, and more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the reaction component. is there. If the amount is less than the above range, the cohesive strength of the water-dispersed pressure-sensitive adhesive composition may be reduced. If the amount is more than the above range, stability during emulsion polymerization and water resistance of the water-dispersed pressure-sensitive adhesive composition are reduced. There is a case.

  The phosphate group-containing vinyl monomer is, for example, a polyalkylene oxide (meth) acrylate phosphate ester represented by the following general formula (1),

(In general formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents a polyoxyalkylene group, and X represents a phosphoric acid group or a salt thereof.)
The polyoxyalkylene group represented by R ² is represented by the following general formula (2),

(In general formula (2), n represents an integer of 1 to 4, and m represents an integer of 2 or more.)
For example, a polyoxyethylene group (corresponding to n = 2 in the general formula (2)), a polyoxypropylene group (corresponding to n = 3 in the general formula (2)) and a random, block or graft unit thereof. The degree of polymerization of these oxyalkylene groups, that is, in the general formula (2), m is preferably 4 or more and usually 40 or less.

The higher the degree of polymerization of the oxyalkylene group, the higher the mobility of the side chain having a phosphate group, and the faster the interaction with the glass, the better the adhesion of the water-dispersed pressure-sensitive adhesive composition to the substrate.
Further, the phosphate group represented by X or a salt thereof is represented by the following general formula (3),

(In general formula (3), M ¹ and M ² each independently represent a hydrogen atom or a cation.)
The cation is not particularly limited, and examples thereof include inorganic cations such as alkali metals such as sodium and potassium, alkaline earth metals such as calcium and magnesium, and organic cations such as quaternary amines.

  Moreover, what is generally marketed can be used for the phosphoric acid group containing vinyl monomer, for example, Sipomer PAM-100 (made by Rhodia Nikka), Phosmer PE (made by Unichemical), Phosmer PEH (Unichemical) Mono [poly (ethylene oxide) methacrylate] phosphate esters such as Phosmer PEDM (Unichemical), for example, Sipomer PAM-200 (Rhodia Nikka), Phosmer PP (Unichemical), Phosmer Examples include mono [poly (propylene oxide) methacrylate] phosphoric acid esters such as PPH (manufactured by Unichemical) and Phosmer PPDM (manufactured by Unichemical).

These phosphate group-containing vinyl monomers can be used alone or in combination.
The mixing ratio of the phosphoric acid group-containing vinyl monomer is, for example, 0.5 to 20 parts by weight, preferably 0.5 to 10 parts by weight, and more preferably 1 to 5 parts by weight with respect to 100 parts by weight of the reaction component. It is. When the amount is less than the above range, the cohesive force may be reduced. When the amount is more than the above range, stability during emulsion polymerization and water resistance of the water-dispersed pressure-sensitive adhesive composition may be reduced.

Examples of the alkoxysilyl group-containing vinyl monomer include silicone-based (meth) acrylate monomers and silicone-based vinyl monomers.
Examples of the silicone-based (meth) acrylate monomer include (meth) acryloyloxymethyl-trimethoxysilane, (meth) acryloyloxymethyl-triethoxysilane, 2- (meth) acryloyloxyethyl-trimethoxysilane, 2- ( (Meth) acryloyloxyethyl-triethoxysilane, 3- (meth) acryloyloxypropyl-trimethoxysilane, 3- (meth) acryloyloxypropyl-triethoxysilane, 3- (meth) acryloyloxypropyl-tripropoxysilane, 3 -(Meth) acryloyloxypropyl-triisopropoxysilane, (meth) acryloyloxyalkyl-trialkoxysilane such as 3- (meth) acryloyloxypropyl-tributoxysilane, for example, (meth) acryloyloxymethyl-methyl Dimethoxysilane, (meth) acryloyloxymethyl-methyldiethoxysilane, 2- (meth) acryloyloxyethyl-methyldimethoxysilane, 2- (meth) acryloyloxyethyl-methyldiethoxysilane, 3- (meth) acryloyloxypropyl -Methyldimethoxysilane, 3- (meth) acryloyloxypropyl-methyldiethoxysilane, 3- (meth) acryloyloxypropyl-methyldipropoxysilane, 3- (meth) acryloyloxypropyl-methyldiisopropoxysilane, 3- (Meth) acryloyloxypropyl-methyldibutoxysilane, 3- (meth) acryloyloxypropyl-ethyldimethoxysilane, 3- (meth) acryloyloxypropyl-ethyldiethoxysilane, 3- (meth) acryloyloxypropyl Ethyl dipropoxysilane, 3- (meth) acryloyloxypropyl-ethyldiisopropoxysilane, 3- (meth) acryloyloxypropyl-ethyldibutoxysilane, 3- (meth) acryloyloxypropyl-propyldimethoxysilane, 3- ( Examples include (meth) acryloyloxyalkyl-alkyl dialkoxysilanes such as (meth) acryloyloxypropyl-propyldiethoxysilane, and (meth) acryloyloxyalkyl-dialkyl (mono) alkoxysilanes corresponding to these.

  Examples of the silicone-based vinyl monomer include vinyltrialkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, and vinyl corresponding to these. Alkyldialkoxysilanes and vinyldialkylalkoxysilanes such as vinylmethyltrimethoxysilane, vinylmethyltriethoxysilane, β-vinylethyltrimethoxysilane, β-vinylethyltriethoxysilane, γ-vinylpropyltrimethoxysilane, γ -Vinylalkyl such as vinylpropyltriethoxysilane, γ-vinylpropyltripropoxysilane, γ-vinylpropyltriisopropoxysilane, γ-vinylpropyltributoxysilane Another trialkoxysilane, these correspond and (vinyl) alkyl dialkoxy silanes, and the like (vinyl alkyl) dialkyl (mono) alkoxysilanes.

Of these alkoxysilyl group-containing vinyl monomers, preferably a silicone-based (meth) acrylate monomer, more preferably 3-methacryloyloxypropyl-trimethoxysilane.
These alkoxysilyl group-containing vinyl monomers can be used alone or in combination.

  The compounding ratio of the alkoxysilyl group-containing vinyl monomer is, for example, 0.001 to 1 part by weight, preferably 0.01 to 0.1 part by weight with respect to 100 parts by weight of the reaction component. If the amount is less than the above range, crosslinking by alkoxysilyl groups is insufficient, resulting in a decrease in cohesive strength of the water-dispersed pressure-sensitive adhesive composition, and improvement in adhesion between the water-dispersed adhesive composition and the substrate. However, when the amount is larger than the above range, there may be a case where the stability or the adhesiveness during emulsion polymerization is lowered.

Moreover, the reaction component can further contain a copolymerizable vinyl monomer copolymerizable with (meth) acrylic acid alkyl ester.
Examples of such copolymerizable vinyl monomers include alicyclic hydrocarbon groups having 6 or more carbon atoms, such as cyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, and the like. (Meth) acrylic acid alicyclic hydrocarbon ester, for example, aromatic vinyl monomer such as styrene, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic (Meth) acrylic acid alkyl esters having 1 to 3 carbon atoms and having a linear or branched alkyl group such as isopropyl acid, for example, (meth) acrylic acid aryl esters such as phenyl (meth) acrylate, for example, Alkoxy group-containing unsaturated monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, such as Olefin monomers such as ethylene, propylene, isoprene, butadiene and isobutylene, vinyl ether monomers such as vinyl ether, halogen atom-containing unsaturated monomers such as vinyl chloride, and others such as N-vinylpyrrolidone, N- ( 1-methylvinyl) pyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine And vinyl group-containing heterocyclic compounds such as tetrahydrofurfuryl (meth) acrylate, for example, acrylic ester monomers containing halogen atoms such as fluorine atoms, such as fluorine (meth) acrylate.

Moreover, as a copolymerizable vinyl monomer, the functional group containing vinyl monomer containing a functional group is mentioned.
Examples of such functional group-containing vinyl monomers include unsaturated carboxylic acids such as fumaric acid, maleic acid, itaconic acid, crotonic acid and cinnamic acid, and unsaturated acids such as itaconic anhydride, maleic anhydride and fumaric anhydride. Carboxyl group-containing vinyl monomers such as saturated dicarboxylic acid anhydrides (excluding (meth) acrylic acid), for example, vinyl acetate, vinyl propionate and other carboxylic acid vinyl esters such as 2-hydroxyethyl acrylate, acrylic acid 2 Hydroxyl group-containing vinyl monomers such as hydroxypropyl and 2-hydroxybutyl acrylate, for example, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) Acrylamide, N-butyl (meth) acrylamide, N-methoxy Amide group-containing unsaturated monomers such as methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-vinylcarboxylic acid amide, such as glycidyl (meth) acrylate, (meth) Glycidyl group-containing unsaturated monomers such as methyl glycidyl acrylate, for example, cyano group-containing unsaturated monomers such as acrylonitrile and methacrylonitrile, for example, isocyanate group-containing unsaturated monomers such as 2-methacryloyloxyethyl isocyanate, such as styrene sulfone Acid, allylsulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamidepropanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalenesulfonic acid, etc. Sulphonic acid group-containing unsaturated monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, and other maleimide monomers such as N-methylitaconimide, N-ethylitaconimide, Itaconimide monomers such as N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, for example, N- (meth) acryloyloxymethylene succinimide, N Succinimide monomers such as-(meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide, for example, (meth) acrylic acid polyethylene Glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxy ethylene glycol, and the like glycol acrylic ester monomers such as (meth) methoxy polypropylene glycol acrylate.

Furthermore, a polyfunctional monomer is mentioned as an above-described functional group containing vinyl monomer.
Examples of the multifunctional monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and tetraethylene glycol di (meth) acrylate. (Mono or poly) alkylene glycol di (meth) such as (mono or poly) ethylene glycol di (meth) acrylate and (mono or poly) propylene glycol di (meth) acrylate such as propylene glycol di (meth) acrylate In addition to acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol Examples include tall tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and divinylbenzene. Examples of the polyfunctional monomer include epoxy acrylate, polyester acrylate, and urethane acrylate.

The copolymerizable vinyl monomer can be used alone or in combination.
Of these copolymerizable vinyl monomers, (meth) acrylic acid alicyclic hydrocarbon ester having an alicyclic hydrocarbon group having 6 or more carbon atoms is preferable, and cyclohexyl methacrylate is more preferable. It is done.
The copolymerizable vinyl monomer is optionally blended in the reaction component, and the blending ratio is, for example, 39 parts by weight or less, preferably 19 parts by weight or less, more preferably 18 parts by weight with respect to 100 parts by weight of the reaction component. Less than parts by weight.

By adding these copolymerizable vinyl monomers to the reaction component, the adhesiveness of the water-dispersed pressure-sensitive adhesive composition can be improved.
In order to obtain a water-dispersed copolymer, the above-described reaction components are copolymerized by a polymerization method such as emulsion polymerization.
In emulsion polymerization, for example, a polymerization initiator, an emulsifier, and a chain transfer agent as necessary are copolymerized in water together with the above-described reaction components. More specifically, for example, known emulsion polymerization methods such as a batch charging method (batch polymerization method), a monomer dropping method, and a monomer emulsion dropping method can be employed. In the monomer dropping method, continuous dropping or divided dropping is appropriately selected. Although reaction conditions etc. are selected suitably, superposition | polymerization temperature is 20-100 degreeC, for example.

  The polymerization initiator is not particularly limited, and a polymerization initiator usually used for emulsion polymerization is used. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2, 2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate, 2,2′-azobis (N, N Azo initiators such as' -dimethyleneisobutylamidine), 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, for example, persulfate such as potassium persulfate and ammonium persulfate Salt-based initiators, for example, peroxide-based initiators such as benzoyl peroxide, t-butyl hydroperoxide, hydrogen peroxide, for example, substituted ethanes such as phenyl-substituted ethane Initiator, for example, carbonyl-based initiators such as aromatic carbonyl compounds, for example, a combination of a persulfate and sodium hydrogen sulfite, and the like redox initiators such as a combination of a peroxide and sodium ascorbate.

These polymerization initiators can be used alone or in combination.
Of these polymerization initiators, a persulfate-based initiator is preferably used, and ammonium persulfate is more preferably used.
The blending ratio of the polymerization initiator is appropriately selected, and is, for example, 0.001 to 1 part by weight with respect to 100 parts by weight of the reaction component.

Note that the dissolved oxygen concentration in the reaction component solution can be reduced by nitrogen substitution before, while or after the polymerization initiator is mixed with the reaction component.
The emulsifier is not particularly limited, and a known emulsifier usually used for emulsion polymerization is used. For example, sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene Anionic emulsifiers such as sodium alkylsulfosuccinate, for example, nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, and polyoxyethylene polyoxypropylene block polymer.

In addition, radically polymerizable (reactive) emulsifiers (for example, HS-10 (No. 1), in which radically polymerizable functional groups (reactive groups) such as propenyl groups and allyl ether groups are introduced into these anionic and nonionic emulsifiers. Ichikogaku Pharmaceutical Co., Ltd.)).
These emulsifiers can be used alone or in combination. Moreover, the mixture ratio of an emulsifier is 0.2-10 weight part with respect to 100 weight part of reaction components, Preferably, it is 0.5-5 weight part.

The chain transfer agent adjusts the molecular weight of the water-dispersed copolymer as required, and a chain transfer agent usually used for emulsion polymerization is used. Examples thereof include mercaptans such as 1-dodecanethiol, mercaptoacetic acid, 2-mercaptoethanol, 2-ethylhexyl thioglycolate, and 2,3-dimethylcapto-1-propanol.
These chain transfer agents can be used alone or in combination. Moreover, the mixture ratio of a chain transfer agent is 0.001-0.5 weight part with respect to 100 weight part of reaction components, for example.

And the water-dispersed copolymer obtained by such emulsion polymerization can be prepared as an emulsion (water dispersion).
The aqueous dispersion is prepared by, for example, polymerizing the above-described reaction components by a method that does not use an organic solvent other than emulsion polymerization to obtain a water-dispersed copolymer, and then using the above-mentioned emulsifier to perform the water-dispersed copolymer. It can also be prepared by dispersing the polymer in water.

The aqueous dispersion is adjusted to, for example, pH 7-9, preferably pH 7-8 with, for example, aqueous ammonia for the purpose of improving the stability of the emulsion.
And the water dispersion type adhesive composition of this invention is obtained by mix | blending the water dispersion type copolymer obtained by the above, and a crosslinking agent.
The cross-linking agent is a cross-linking agent having an oxazoline group (oxazoline-based cross-linking agent), and includes, for example, a main chain composed of an acrylic skeleton or a styrene skeleton, and has an oxazoline group in the side chain of the main chain. And preferably, the oxazoline group containing acrylic polymer which contains the principal chain which consists of an acrylic skeleton, and has the oxazoline group in the side chain of the principal chain is mentioned.

Examples of the oxazoline group include 2-oxazoline group, 3-oxazoline group, 4-oxazoline group, and preferably 2-oxazoline group.
The 2-oxazoline group is generally represented by the following general formula (4).

(In the general formula (4), R ¹² , R ¹³ , R ¹⁴ and R ¹⁵ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, a phenyl group or a substituted phenyl group.)
The oxazoline group-containing polymer can be used as an emulsion type emulsified in water using an emulsifier or an aqueous solution type dissolved in water.
The number average molecular weight of the oxazoline group-containing polymer is, for example, 5000 or more, preferably 10,000 or more, and usually 1000000 or less. When the number average molecular weight is lower than 5000, the strength of the undercoat layer is insufficient, causing cohesive failure, and the anchoring force may not be improved. When the number average molecular weight is higher than 1,000,000, workability may be inferior. The oxazoline group-containing polymer has an oxazoline value of, for example, 1500 g solid / eq. Hereinafter, preferably, 1200 g solid / eq. It is as follows. The oxazoline value is 1500 g solid / eq. If it is larger, the amount of the oxazoline group contained in the molecule decreases, and the anchoring force may not be improved.

  As the oxazoline group-containing polymer, a general commercial product is usually used. Specifically, as an aqueous solution type, Epocros WS-500 (solid content 40%, main chain: acrylic, pH 7 to 9, oxazoline value 220 g solid / eq., manufactured by Nippon Shokubai Co., Ltd.), Epocros WS-700 (solid content 25%, main chain: acrylic, pH 7-9, oxazoline value 220 g solid / eq., manufactured by Nippon Shokubai Co., Ltd.), etc. For example, Epocross K-1000 series (solid content 40%, main chain: styrene / acrylic, oxazoline number 1100 g solid / eq., PH 7-9, manufactured by Nippon Shokubai Co., Ltd.), Epocross K- 2000 series (solid content 40%, main chain: styrene / acrylic, pH 7-9, Kisazorin value 550 g solid / eq., Manufactured by Nippon Shokubai Co., Ltd.) oxazoline group-containing acrylic / styrene polymers and the like. From the viewpoint of improving adhesion, an aqueous solution type is preferable to an emulsion type containing an emulsifier.

These oxazoline-based crosslinking agents can be used alone or in combination of two or more.
Since such an oxazoline-based crosslinking agent is contained in the water-dispersed pressure-sensitive adhesive composition, the oxazoline group mainly reacts with a functional group (mainly, a carboxyl group of (meth) acrylic acid) at a relatively low temperature. Therefore, a strong pressure-sensitive adhesive layer can be formed.
The blending ratio of the oxazoline-based crosslinking agent is 0.07 to 1.5 parts by weight, preferably 0.1 to 1 with respect to 100 parts by weight of the water-dispersed copolymer (that is, the solid content of the aqueous dispersion). Part by weight, more preferably 0.1 to 0.3 part by weight. When the amount is less than the above range, foaming of the pressure-sensitive adhesive layer in a high temperature atmosphere cannot be suppressed. On the other hand, when the amount is larger than the above range, the adhesiveness (tackiness) of the water-dispersed pressure-sensitive adhesive composition, in particular, the adhesive force during heating and humidification is lowered. In addition, as for the adhesive force at the time of a heating and humidification (90 degree peeling adhesive force: peeling speed [10 mm / min]), 0.7 N / 25mm or more is desirable.

In addition to the oxazoline-based crosslinking agent, the crosslinking agent may optionally include, for example, a carbodiimide-based crosslinking agent, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an aziridine-based crosslinking agent, a metal chelate-based crosslinking agent, and the like. It can be included in a blending ratio.
By mixing the water-dispersed copolymer and the crosslinking agent, the water-dispersed copolymer is crosslinked. More specifically, the carboxyl group of the water-dispersed copolymer reacts with the oxazoline group of the oxazoline-based crosslinking agent to crosslink the water-dispersed copolymer.

In addition, after mix | blending a water-dispersed copolymer and a crosslinking agent, in order to accelerate | stimulate a crosslinking reaction, it can also heat at 80-120 degreeC, for example, 1-10 minutes, for example. In addition, this heating can also utilize the heating by drying at the time of formation of the adhesive layer mentioned later.
Furthermore, the obtained water-dispersed pressure-sensitive adhesive composition includes, as necessary, a viscosity modifier, a release modifier, a plasticizer, a softener, a filler, a colorant (pigment, dye, etc.), an anti-aging agent, Additives usually added to the water-dispersed pressure-sensitive adhesive composition such as a surfactant may be appropriately added. The mixing ratio of these additives is not particularly limited, and can be appropriately selected.

  The gel fraction of the water-dispersed pressure-sensitive adhesive composition (solid content) thus prepared is, for example, 80 to 95% by weight, preferably 80 to 93% by weight. If the gel fraction is lower than the above value, foaming may occur when this water-dispersed pressure-sensitive adhesive composition is applied to a pressure-sensitive adhesive optical film and used in a high-temperature atmosphere. Moreover, when the gel fraction is higher than the above-described value, the adhesive strength of the water-dispersed pressure-sensitive adhesive composition may be reduced.

The gel fraction can be calculated by the following formula when the water-dispersed pressure-sensitive adhesive composition is covered with a Teflon sheet (registered trademark) and immersed in ethyl acetate for 7 days.
Gel fraction (% by weight) = (weight of water-dispersed pressure-sensitive adhesive composition adhering to the Teflon sheet after immersion) / weight of water-dispersed pressure-sensitive adhesive composition before immersion) × 100
Hereinafter, with reference to FIG. 1, the manufacturing method of the adhesive optical film which is one Embodiment of the adhesive film of this invention is demonstrated.

In order to obtain an adhesive optical film, first, the optical film 1 is prepared.
The optical film 1 is not particularly limited as long as it has optical characteristics and is attached to a liquid crystal display, and examples thereof include a polarizing film, a retardation film, a brightness enhancement film, and a viewing angle widening film. .
As a polarizing film, what provided the transparent protective film on the single side | surface or both surfaces of a polarizer is used.

  The polarizer is not particularly limited, and examples thereof include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, ethylene / vinyl acetate copolymer partially saponified films, iodine and dichroism. Examples thereof include uniaxially stretched films dyed with dichroic substances such as dyes, and polyene-based oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Preferably, a polarizer obtained by uniaxially stretching a polyvinyl alcohol film with iodine is used.

  Examples of the transparent protective film include polyester polymer films such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymer films such as diacetyl cellulose and triacetyl cellulose, acrylic polymer films such as polymethyl methacrylate, polystyrene, acrylonitrile and styrene. Examples thereof include a styrene polymer film such as a polymer (AS resin), and a polycarbonate polymer film. In addition, polyethylene, polypropylene, polyolefin having a cyclo or norbornene structure, polyolefin polymer film such as ethylene / propylene copolymer, vinyl chloride polymer film, nylon, amide polymer film such as aromatic polyamide, imide polymer film, Sulfone polymer film, polyether sulfone polymer film, polyether ether ketone polymer film, polyphenylene sulfide polymer film, vinyl alcohol polymer film, vinylidene chloride polymer film, vinyl butyral polymer film, arylate polymer film, poly Of oxymethylene-based polymer film, epoxy-based polymer film, or blends of the above-mentioned polymers Irumu also include such.

The transparent protective film can also be formed as a cured layer of thermosetting or ultraviolet curable resin such as acrylic, urethane, acrylurethane, epoxy, and silicone.
As a transparent protective film, Preferably, a cellulose polymer is mentioned. The thickness in particular of a transparent protective film is not restrict | limited, For example, it is 500 micrometers or less, Preferably, it is 1-300 micrometers, More preferably, it is 5-200 micrometers.

In order to bond the polarizer and the transparent protective film, for example, an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based adhesive, a latex-based adhesive, a water-based polyester adhesive, or the like is used. Glue.
Examples of the retardation film include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by the film. The thickness of the retardation film is not particularly limited and is, for example, 20 to 150 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyvinyl alcohol, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose polymer, or binary, ternary copolymers, graft copolymers, blends Such as things. These polymer materials become an oriented product (stretched film) by stretching or the like.

  Examples of the liquid crystalline polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal orientation is introduced into the main chain or side chain of the polymer. It is done. As the main chain type liquid crystalline polymer, for example, a structure in which a mesogenic group is bonded at a spacer portion imparting flexibility, specifically, a nematic orientation polyester-based liquid crystalline polymer, a discotic polymer or a cholesteric polymer. Etc. As the side chain type liquid crystalline polymer, for example, polysiloxane, polyacrylate, polymethacrylate or polymalonate is used as the main chain skeleton, and the side chain is substituted by a nematic orientation-imparting para-substitution through a spacer portion composed of a conjugated atomic group. Examples thereof include those having a mesogenic part composed of a cyclic compound unit. These liquid crystalline polymers are prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment-treated surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. It is obtained by developing and heat treatment.

In addition, the retardation film may be, for example, a film for the purpose of expanding coloring or viewing angle due to birefringence of various wavelength films or liquid crystal layers, or may have a phase difference as appropriate depending on the purpose of use. Two or more retardation films may be laminated to control optical characteristics such as retardation.
Examples of brightness enhancement films are those that transmit linearly polarized light with a predetermined polarization axis and reflect other light, such as dielectric multilayer thin films and multilayer laminates of thin film films with different refractive index anisotropies. , Cholesteric liquid crystal polymer alignment films and those whose alignment liquid crystal layer is supported on a film substrate, such as those that reflect either left-handed or right-handed circularly polarized light and transmit other light, etc. Is mentioned.

  The viewing angle widening film is a film that widens the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display is viewed from a slightly oblique direction rather than perpendicular to the screen. Examples thereof include an alignment film such as a film and a liquid crystal polymer, and a support in which an alignment layer such as a liquid crystal polymer is supported on a transparent substrate. Retardation films used as viewing angle widening films include birefringent polymer films stretched biaxially in the plane direction and thickness direction refractions stretched uniaxially in the plane direction and stretched in the thickness direction. A birefringent film such as a polymer having birefringence with a controlled rate or a tilted orientation film is used.

And the adhesive layer 2 which consists of a water dispersion-type adhesive composition is provided in the single side | surface of the optical film 1. FIG.
In order to provide the pressure-sensitive adhesive layer 2, for example, the pressure-sensitive adhesive layer 2 is transferred to the optical film 1 from the release sheet 3 on which the pressure-sensitive adhesive layer 2 is formed. The release sheet 3 on which the pressure-sensitive adhesive layer 2 is formed is directly coated with a water-dispersed pressure-sensitive adhesive composition on the release sheet 3 by a known coating method such as a knife coating method. Thereafter, the pressure-sensitive adhesive layer 2 is provided on the release sheet 3 by heating and drying at 80 to 150 ° C. for 1 to 10 minutes, for example. In order to transfer the pressure-sensitive adhesive layer 2, the release sheet 3 on which the pressure-sensitive adhesive layer 2 is formed is bonded to the optical film 1, and then the release sheet 3 is peeled off from the pressure-sensitive adhesive layer 2.

In order to provide the pressure-sensitive adhesive layer 2, for example, the optical film 1 is directly coated with a water-dispersed pressure-sensitive adhesive composition by a known coating method such as a knife coating method. It can also be dried by heating at 150 ° C. for 1 to 10 minutes.
In addition, as shown in FIG. 2, the optical film 1 can be subjected to undercoating treatment such as providing an undercoat layer 4 in advance in order to improve the adhesive force (throwing force) with the pressure-sensitive adhesive layer 2. .

The undercoat layer 4 includes, for example, a resin, and examples of such a resin include a polyacrylic resin, a polyurethane resin, and a polyester resin, and preferably a resin obtained by modifying these resins with a reactive functional group. Is mentioned.
Examples of the reactive functional group include an oxazoline group, a carboxyl group, a hydroxyl group, and an amino group, and preferably an oxazoline group.

Examples of the oxazoline group include the same as those described above.
More specifically, as a resin modified with a reactive functional group, for example, when the reactive functional group is an oxazoline group, it includes a main chain composed of an acrylic skeleton or a styrene skeleton, and the side chain of the main chain includes An oxazoline group-containing acrylic polymer similar to that described above is preferably used.

Such resins are used alone or in combination. Such a resin is usually dissolved or dispersed in an organic solvent or water so that the blending ratio of the solid content is 0.01 to 15% by weight, preferably 0.05 to 5% by weight. Has been prepared.
In order to provide the undercoat layer 4, for example, an undercoat liquid (solution or dispersion) containing a resin is directly applied to the optical film 1 by a known application method such as a coating method, a dipping method, or a spray method and then dried. A method is mentioned.

The thickness of the undercoat layer 4 is, for example, 1 to 500 μm, preferably 10 to 100 μm, more preferably 20 to 50 μm before drying, and the thickness after drying is, for example, 1 to 1000 nm, preferably The thickness is set to 10 to 500 nm, more preferably 20 to 400 nm.
Examples of the release sheet 3 include synthetic resin films such as paper, polyethylene, polypropylene, and polyethylene terephthalate, such as rubber sheets, cloths, nonwoven fabrics, nets, foam sheets, metal foils, and laminated sheet bodies thereof. The surface of the release sheet 3 may be subjected to treatment (peeling treatment) such as silicone treatment, long-chain alkyl treatment, and fluorine treatment as necessary in order to enhance the peelability from the pressure-sensitive adhesive layer 2.

The thickness (thickness after drying) of the pressure-sensitive adhesive layer 2 is set, for example, in the range of 1 to 100 μm, preferably 5 to 50 μm, and more preferably 10 to 30 μm.
The pressure-sensitive adhesive layer 2 composed of the water-dispersed pressure-sensitive adhesive composition described above has an elongation at 90 ° C. of, for example, 200% or less, preferably 100% or less, more preferably 50% or less, usually 0, according to the following test. % Or more.

Elongation test at 90 ° C .: A pressure-sensitive adhesive layer is prepared by heating a water-dispersed pressure-sensitive adhesive composition, and this is molded into a cylindrical shape having a cross-sectional area of 4.6 mm ² and a length of 30 mm to produce a test piece. To do. Then, the specimen was left for 1 hour at 90 ° C., to measure the length L ₀ of the initial specimen. Thereafter, one end of the test piece is fixed, a 12 g weight is attached to the other end of the test piece, the test piece is suspended at 90 ° C. for 2 hours, and the length L ₁ (mm) of the test piece after being suspended for 2 hours. And the elongation is calculated by the following formula.

Elongation (%) = (L ₁ −L ₀ ) / L ₀ × 100
When the elongation at 90 ° C. exceeds the above-described range, the foam resistance of the pressure-sensitive adhesive layer 2 under a high temperature atmosphere is lowered, and foaming cannot be suppressed.
The pressure-sensitive adhesive layer 2 has an elongation at 23 ° C. of, for example, 100% or less, preferably 80% or less, more preferably 50% or less, usually 0% or more.

The elongation at 23 ° C. can be calculated in the same manner as the above-described elongation test at 90 ° C. except that 90 ° C. is changed to 23 ° C. in the above-described elongation test at 90 ° C.
Thus, an adhesive optical film can be obtained by providing the adhesive layer 2 made of the water-dispersed adhesive composition on one surface of the optical film 1.

The adhesive optical film thus obtained is suitably used for various industrial applications as an adhesive optical film such as a polarizing film, a retardation film, a brightness enhancement film, and a viewing angle widening film.
Since the water-dispersed pressure-sensitive adhesive composition of the present invention has high adhesiveness even when bonded to a glass substrate, the pressure-sensitive optical film can be firmly bonded to the glass substrate.

Furthermore, since this pressure-sensitive optical film has high heat resistance and moisture resistance, excellent durability can be obtained even in a high-temperature and high-humidity atmosphere.
In particular, the water-dispersed pressure-sensitive adhesive composition of the present invention and the pressure-sensitive adhesive optical film provided with a pressure-sensitive adhesive layer comprising the water-dispersed pressure-sensitive adhesive composition are effective in generating bubbles and distortion at high temperatures and high humidity. Can be prevented. Therefore, it is possible to effectively prevent a decrease in optical characteristics.

In the above description, the pressure-sensitive adhesive film of the present invention has been described by exemplifying a pressure-sensitive adhesive optical film. However, the pressure-sensitive adhesive film can be used as a pressure-sensitive adhesive film to be attached to an adherend other than the optical film. Moreover, the adhesive film of this invention is used also as an adhesive sheet, an adhesive tape, etc., for example.
In the above description, the pressure-sensitive adhesive layer 2 and the undercoat layer 4 provided as necessary are provided on one side of the optical film 1, but can also be provided on both sides of the optical film 1.

  In addition, in a normal water-dispersed pressure-sensitive adhesive composition, a rosin resin, a tackifying resin such as an elastomer, and the like are added in order to increase adhesion to an adherend. Although the composition is water-dispersed, it can improve adhesion without adding such a tackifier resin, and thus the water-dispersed pressure-sensitive adhesive composition having high adhesion at low cost, and this A pressure-sensitive adhesive film having a pressure-sensitive adhesive layer made of such a water-dispersed pressure-sensitive adhesive composition can be obtained.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples and comparative examples. In the following description, “parts” and “%” are based on weight unless otherwise specified.
Example 1
(Preparation of monomer pre-emulsion)
In a container, 88 parts of butyl acrylate, 5 parts of acrylic acid, 5 parts of cyclohexyl methacrylate, mono [poly (propylene oxide) methacrylate] phosphate ester (average degree of polymerization of propylene oxide of about 5.0, Sipomer PAM-200, Rhodia 2 parts of Nikka Corporation) and 0.03 part of 3-methacryloyloxypropyl-trimethoxysilane (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed to prepare reaction components. Next, 46.6 g of reactive emulsifier Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.) and 109 g of ion-exchanged water are added to 388 g of the prepared reaction component, and 5000 minutes is used for 5 minutes using a homogenizer (manufactured by Tokushu Kika Co., Ltd.). A monomer pre-emulsion was prepared by stirring and forcibly emulsifying at (1 / min).
(Preparation of water-dispersed copolymer emulsion)
54 g of the monomer pre-emulsion prepared above and 456 g of ion-exchanged water were charged into a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirrer. 3 g was added and polymerized at 65 ° C. for 2.5 hours. Next, 489.6 g of the remaining monomer pre-emulsion was dropped into the reaction vessel over 3 hours, and then polymerized for 3 hours. Thereafter, while replacing with nitrogen, the mixture was further treated at 75 ° C. for 3 hours to obtain an aqueous dispersion copolymer emulsion (aqueous dispersion) having a solid content of 40%.
(Preparation of water-dispersed pressure-sensitive adhesive composition)
The obtained emulsion was cooled to room temperature, 10% aqueous ammonia was added to adjust the pH to 8, and oxazoline-based crosslinking agent (Epocross WS-700, oxazoline group-containing acrylic polymer, aqueous solution type, Nippon Shokubai) 0.1 part) was added to 100 parts of emulsion solids (water-dispersed copolymer) to prepare a water-dispersed pressure-sensitive adhesive composition.
(Preparation of adhesive optical film)
The prepared water-dispersed pressure-sensitive adhesive composition was coated on a release sheet made of a polyester film treated with a release agent, and heated at 100 ° C. for 2 minutes to dry to form a pressure-sensitive adhesive layer having a thickness of 23 μm. .

  In addition, a polarizing film (Y-TEG5463DU, manufactured by Nitto Denko Corporation) that had been primed in advance was prepared. In the undercoating treatment, first, an oxazoline group-containing acrylic polymer (Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd.) is mixed with water and ethanol in a mixed solvent (volume ratio of 1: 1) to a solid content of 2% by weight. A primer solution diluted as described above was prepared. Next, this undercoat solution was applied to one side of the polarizing film using wire bar # 5 and dried by heating at 40 ° C. for 2 minutes to provide an undercoat layer.

Next, this polarizing film was laminated on the retardation film (NAZ- # 195-0.3, manufactured by Nitto Denko Corporation) so that the surface on which the undercoat layer was not provided and the retardation film were bonded together. . Thereby, an optical film in which a polarizing film provided with an undercoat layer and a retardation film were laminated was produced.
Subsequently, the pressure-sensitive adhesive layer was laminated on the undercoat layer of the optical film to produce a pressure-sensitive adhesive optical film (see FIG. 2).

Example 2
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 1, water was prepared in the same manner as in Example 1 except that 0.3 part of the oxazoline-based crosslinking agent was added instead of 0.1 part of the oxazoline-based crosslinking agent. A dispersion-type pressure-sensitive adhesive composition was prepared, and subsequently, a pressure-sensitive adhesive optical film was produced.
Example 3
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 1, in place of 0.1 part of the oxazoline-based crosslinking agent, 1 part of the oxazoline-based crosslinking agent was added, and the water-dispersed type was prepared in the same manner as in Example 1. An adhesive composition was prepared, and subsequently an adhesive optical film was produced.

Comparative Example 1
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 1, water was prepared in the same manner as in Example 1 except that 0.001 part of the oxazoline-based crosslinking agent was added instead of 0.1 part of the oxazoline-based crosslinking agent. A dispersion-type pressure-sensitive adhesive composition was prepared, and subsequently, a pressure-sensitive adhesive optical film was produced.
Comparative Example 2
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 1, water was prepared in the same manner as in Example 1 except that 0.05 part of the oxazoline-based crosslinking agent was added instead of 0.1 part of the oxazoline-based crosslinking agent. A dispersion-type pressure-sensitive adhesive composition was prepared, and subsequently, a pressure-sensitive adhesive optical film was produced.

Comparative Example 3
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 1, in place of 0.1 part of the oxazoline-based crosslinking agent, 2 parts of oxazoline-based crosslinking agent was added, and the water-dispersed type was prepared in the same manner as in Example 1. An adhesive composition was prepared, and subsequently an adhesive optical film was produced.
Comparative Example 4
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 1, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that no oxazoline-based crosslinking agent was added. A mold optical film was prepared.

(Evaluation)
1) Elongation of pressure-sensitive adhesive layer A pressure-sensitive adhesive layer having a thickness of 23 µm was prepared by heating the water-dispersed pressure-sensitive adhesive composition in each example and each comparative example at 100 ° C for 2 minutes. After the pressure-sensitive adhesive layer was cooled, it was formed into a 200 mm × 30 mm planar view rectangular sheet shape with a spatula. Next, this was wound by hand to be molded into a cylindrical shape having a cross-sectional area of 4.6 mm ² and a length of 30 mm, thereby preparing a test piece. Next, 10 mm portions at both ends in the longitudinal direction of the test piece were sandwiched between clips. Then, the test piece was allowed to stand for 1 hour in an atmosphere of 23 ° C. (room temperature) and 90 ° C.

Thereafter, the length in the longitudinal direction (initial length) L ₀ (mm) not sandwiched between the clips in the test piece was measured with a ruler in advance. Next, the clip at one end of the test piece was fixed, a 12 g weight was attached to the clip at the other end of the test piece, and the test piece was suspended for 2 hours in an atmosphere of 23 ° C. (room temperature) and 90 ° C. The length L ₁ (mm) in the longitudinal direction that is not fixed by the clip in the test piece after hanging for 2 hours was measured with a ruler. The initial length L ₀ is about 10 mm.

And the elongation in 2 hours at 23 degreeC and the elongation in 2 hours at 90 degreeC were computed from the following formula, respectively. The results are shown in Table 1.
Elongation (%) = (L ₁ −L ₀ ) / L ₀ × 100
2) Gel fraction The water-dispersed pressure-sensitive adhesive composition (about 100 mg) of each example and each comparative example was first measured with a pre-weighed Teflon sheet (registered trademark, product number: NTF-1122) and octopus yarn (12 cm). Wrapping and weighing this wrap. The packet was then placed in a 50 ml glass bottle, and then enough ethyl acetate was added to seal the glass bottle and soaked at room temperature for 7 days. Thereafter, the soaked package was taken out and wiped off the ethyl acetate adhering to the Teflon sheet, and then the package was dried in a dryer at 130 ° C. for 2 hours. Thereafter, the package after drying was weighed. And the gel fraction was computed by the following formula.

Gel fraction (% by weight) = {(C−A) / (B−A)} × 100
The details of the symbols in the formula are as follows.
A (g): Total weight of Teflon sheet and octopus yarn (tare weight)
B (g): Teflon sheet and octopus yarn and water-dispersed pressure-sensitive adhesive composition immersed in ethyl acetate, total weight before drying C (g): Teflon sheet and octopus yarn, water-dispersed pressure-sensitive adhesive composition Table 1 shows the total weight after immersion in ethyl acetate and drying.

3) Glass adhesiveness The adhesive optical film obtained in each Example and each Comparative Example was cut into a width of 25 mm and adhered to a glass plate (Corning # 1737, manufactured by Corning) to give 2 kg of rubber. The roller was reciprocated once and pressure-bonded, left in an autoclave at 50 ° C. and 0.5 MPa for 15 minutes, then cooled to 25 ° C., and a 90 ° peel adhesive force (peel rate 10 mm / min) was measured ( Initial adhesive strength).

In addition, after being left in an autoclave, it was further left for 40 hours in an atmosphere of 60 ° C. and 60 ° C./90% RH, then cooled to 25 ° C., and 90 ° peel adhesive strength (peel rate 10 mm / min). The results are shown in Table 1.
In addition, it shows that glass adhesiveness is so favorable that the value of peeling adhesive force is high.
4) Heat-foaming property of adhesive optical film The adhesive optical film of each example and each comparative example was cut into a size of 235 mm wide by 310 mm long, and this was cut into a 0.7 mm glass plate (Corning # 1737). , Manufactured by Corning Co., Ltd.) and pressure-bonded by reciprocating a 2 kg rubber roller once. Thereafter, it was left in an autoclave at 50 ° C. and 0.5 MPa for 15 minutes, and then left in an atmosphere heated to 90 ° C. for 500 hours. Thereafter, the presence or absence of foaming of the adhesive optical film was visually observed.

In addition, the presence or absence of foaming in the pressure-sensitive adhesive optical film was observed according to the following criteria.
○: No foaming was observed Δ: Foaming was slightly observed ×: Foaming was observed

Abbreviations in Table 1 are shown below.
PAM-200: Sipomer PAM-200 (mono [poly (propylene oxide) methacrylate) phosphate ester (average degree of polymerization of propylene oxide of about 5.0), manufactured by Rhodia Nikka Co., Ltd.)
KBM-503: 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
Epocros WS-700: Oxazoline group-containing acrylic polymer (aqueous solution, solid content 25%, main chain: acrylic, pH 7-9, oxazoline number 220 g solid / eq., Manufactured by Nippon Shokubai Co., Ltd.)

It is an expanded sectional view of the adhesion type optical film which is one embodiment of the adhesion film of the present invention. It is an expanded sectional view of the adhesion type optical film which is other embodiments of the adhesion film of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical film 2 Adhesive layer 3 Release sheet 4 Undercoat layer

Claims (3)

Reaction component containing (meth) acrylic acid alkyl ester having 4 to 18 carbon atoms and having a linear or branched alkyl group, (meth) acrylic acid, phosphoric acid group-containing vinyl monomer and alkoxysilyl group-containing vinyl monomer A water-dispersed copolymer obtained by reacting with
A water-dispersed pressure-sensitive adhesive composition comprising a crosslinking agent having an oxazoline group,
The blending ratio of the crosslinking agent is 0.07 to 1.5 parts by weight with respect to 100 parts by weight of the water-dispersed copolymer,
The water-dispersed pressure-sensitive adhesive composition is characterized in that the pressure-sensitive adhesive layer comprising the water-dispersed pressure-sensitive adhesive composition has an elongation at 90 ° C. of 200% or less according to the following test.
Test: A pressure-sensitive adhesive layer is prepared by heating a water-dispersed pressure-sensitive adhesive composition, and this is molded into a cylindrical shape having a cross-sectional area of 4.6 mm ² and a length of 30 mm to prepare a test piece. Then, the specimen was left for 1 hour at 90 ° C., to measure the length L ₀ of the initial specimen. Thereafter, one end of the test piece is fixed, a 12 g weight is attached to the other end of the test piece, the test piece is suspended at 90 ° C. for 2 hours, and the length L ₁ (mm) of the test piece after being suspended for 2 hours. And the elongation is calculated by the following formula.
Elongation (%) = (L ₁ −L ₀ ) / L ₀ × 100   The water-dispersed pressure-sensitive adhesive composition according to claim 1, wherein the water-dispersed pressure-sensitive adhesive composition has a gel fraction of 80 to 95% by weight when immersed in ethyl acetate.   An adhesive film comprising an adhesive layer made of the water-dispersed adhesive composition according to claim 1.

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