JP5250292B2 - Adhesive optical film - Google Patents

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 an optical film attached to an image display device, 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 to provide a water-dispersed pressure-sensitive adhesive composition having high adhesion to a glass substrate and having high heat resistance and moisture resistance, and a pressure-sensitive adhesive provided with a pressure-sensitive adhesive layer comprising the water-dispersed pressure-sensitive adhesive composition. To provide a film.

  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 containing 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 crosslinking agent having reactivity with a carboxyl group It is a dispersion-type pressure-sensitive adhesive composition, and the blending ratio of the crosslinking agent is 0.07 to 4 parts by weight with respect to 100 parts by weight of the water-dispersion type copolymer. The resulting pressure-sensitive adhesive layer is characterized in that the elongation by 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 crosslinking agent is a compound having a carbodiimide group.
In the water-dispersed pressure-sensitive adhesive composition of the present invention, it is preferable that the gel fraction when immersed in ethyl acetate is 80 to 95% by weight.
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 including a pressure-sensitive adhesive layer made of the water-dispersed pressure-sensitive adhesive composition have high adhesive strength with a glass substrate and can achieve strong adhesion. it can. 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-mentioned range, stability during emulsion polymerization and water resistance of the water-dispersed pressure-sensitive adhesive composition are reduced. There is a case.

  The phosphoric acid 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. and the like, the degree of polymerization of these oxyalkylene groups, to a KazuSatoshi in 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 glass 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 a phosphoric acid group containing vinyl monomer, for example, Sipomer PAM-100 (made by Rhodia Nikka Co., Ltd.), Phosmer PE (made by Unichemical Co., Ltd.), Phosmer. Mono [poly (ethylene oxide) methacrylate] phosphate esters such as PEH (Unichemical Co., Ltd.) and Phosmer PEDM (Unichemical Co., Ltd.), for example, Sipomer PAM-200 (Rodia Nikka Co., Ltd.), Mono [poly (propylene oxide) methacrylate] phosphates such as Phosmer PP (manufactured by Unichemical Co., Ltd.), Phosmer PPH (manufactured by Unichemical Co., Ltd.), and Phosmer PPDM (manufactured by Unichemical Co., Ltd.). .

These phosphate group-containing vinyl monomers can be used alone or in combination.
The phosphate group concentration of the phosphate group-containing vinyl monomer is, for example, 0.01 to 0.45 mmol / g, preferably 0.02 to 0.20 mmol / g in the reaction components. In order to make the phosphoric acid group concentration of the phosphoric acid group-containing vinyl monomer within the above-mentioned range, although depending on the molecular weight of the phosphoric acid group-containing vinyl monomer, the proportion of the phosphoric acid group-containing vinyl monomer is 100 parts by weight of the reaction component 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.

  If the phosphate group concentration and the blending ratio of the phosphate group-containing vinyl monomer are less than the above range, the effect of improving the adhesion to the glass substrate may not be sufficiently obtained. If the phosphate group concentration and the blending ratio of the phosphate group-containing vinyl monomer are larger than the above ranges, the stability during emulsion polymerization and the water resistance of the water-dispersed pressure-sensitive adhesive composition may decrease, and the water dispersion The adhesiveness may decrease due to an increase in the elastic modulus of the mold pressure-sensitive adhesive composition.

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. When the amount is less than the above range, insufficient crosslinking by alkoxysilyl groups, or cause a decrease in the cohesive force of the water-dispersed PSA composition, the improvement of adhesion between the water-dispersible pressure-sensitive Chakuzai composition and a glass substrate Is not obtained, and when the amount is more than the above range, the stability during emulsion polymerization and the adhesion may be 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, and hydrogen peroxide, for example, substituted ethers such as phenyl-substituted ethane. For example, carbonyl initiators such as aromatic carbonyl compounds, redox initiators such as a combination of persulfate and sodium bisulfite, a combination of peroxide and sodium ascorbate, etc. It is done.

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. Ichi Kogyo Seiyaku 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 water-dispersed copolymer can also be prepared, for example, by polymerizing the above-described reaction components by a method that does not use an organic solvent other than emulsion polymerization, and then dispersing in water with the above-described emulsifier. .

The water-dispersed copolymer is adjusted to, for example, pH 7-9, preferably pH 7-8, for example, with ammonia water 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.
As the crosslinking agent, a crosslinking agent having reactivity with a carboxyl group (mainly a carboxyl group that (meth) acrylic acid has), such as a carbodiimide crosslinking agent, an isocyanate crosslinking agent, an epoxy crosslinking agent, Examples include oxazoline-based crosslinking agents, aziridine-based crosslinking agents, metal chelate-based crosslinking agents, and the like. As the crosslinking agent, a carbodiimide-based crosslinking agent is preferably used.

As the crosslinking agent, for example, an oil-soluble or water-soluble crosslinking agent is used, or a crosslinking agent prepared as a water dispersion type (emulsion type) is also used. As the crosslinking agent, a water-dispersed crosslinking agent is preferably used, and a water-dispersed carbodiimide-based crosslinking agent is more preferably used.
By using a water-dispersible carbodiimide cross-linking agent as a cross-linking agent that is reactive with the carboxyl group of the water-dispersible copolymer, a change occurs in the liquid physical properties, specifically the viscosity, after the cross-linking agent is blended. It is difficult to handle the water-dispersed pressure-sensitive adhesive composition in the production process.

A carbodiimide-based crosslinking agent is a compound having a carbodiimide group. The carbodiimide group is a functional group in which one hydrogen atom is extracted from carbodiimide (HN = C = NH) (-N = C = NH), or a functional group in which two hydrogen atoms are extracted (-N = C = NH). N-). This carbodiimide group can react with a carboxyl group.
More specifically, examples of the carbodiimide-based crosslinking agent include a low molecular compound or a high molecular compound having two or more carbodiimide groups.

The low molecular weight compound having a carbodiimide group is represented by the following general formula, for example.
R ¹ —N═C═N—R ² —N═C═N—R ³
(In the formula, R ¹ , R ² and R ³ are different and represent a hydrocarbon group.)
The polymer compound having a carbodiimide group is polycarbodiimide, and preferably a polymer compound having a portion having excellent affinity with water, for example, an ethylene oxide (—CH ₂ —CH ₂ —O—) site. Can be mentioned.

  As the above-described polymer compound having a carbodiimide group, for example, commercially available compounds can be used. For example, water-soluble carbodilite V series (trade names: carbodilite V-02, carbodilite V-02-L2, carbodilite. V-04, manufactured by Nisshinbo Co., Ltd.), for example, emulsion type (water dispersion type) Carbodilite E series (trade names: Carbodilite E-01, Carbodilite E-02, Carbodilite E-04. Nisshinbo Co., Ltd. Etc.).

These carbodiimide crosslinking agents can be used alone or in combination.
Of these carbodiimide-based crosslinking agents, a polymer compound having a carbodiimide group is preferable.
The mixing ratio of the crosslinking agent is 0.07 to 4 parts by weight, preferably 0.08 to 3 parts by weight, based on 100 parts by weight of the water-dispersed copolymer (that is, the solid content of the aqueous dispersion). Preferably, it is 0.1 to 2 parts by weight. If it 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, if it is more than the above range, the adhesiveness (tackiness) of the water-dispersed pressure-sensitive adhesive composition, particularly heating and humidification Adhesive strength to the glass substrate at the time decreases. 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]), 2.0 N / 25mm or more is desirable.

By mixing the water-dispersed copolymer and the crosslinking agent, the water-dispersed copolymer is crosslinked. More specifically, when the crosslinking agent is a carbodiimide-based crosslinking agent, the carboxyl group of the water-dispersed copolymer reacts with the carbodiimide group of the carbodiimide-based crosslinking agent to crosslink the water-dispersed copolymer. Is done.
In addition, after mix | blending a water dispersion type copolymer and a crosslinking agent, in order to accelerate | stimulate a crosslinking reaction, it heats, for example, 80-150 degreeC, Preferably, 80-120 degreeC, for example, 1-10 minutes. You can also. 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. When 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 attached to Teflon sheet (registered trademark) 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 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 ¹¹ , R ¹² , R ¹³ and R ¹⁴ each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, a phenyl group or a substituted phenyl group.)
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 having an oxazoline group, preferably including a main chain composed of an acrylic skeleton, and having an oxazoline group in the side chain of the main chain.

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 above-described water-dispersed pressure-sensitive adhesive composition has an elongation at 90 ° C. of 200% or less, preferably 180% or less, more preferably 150% or less, particularly preferably 100, according to the following test. % Or less, most preferably 50% or less, usually 0% 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, 150% or less, preferably 130% or less, more preferably 100% or less, particularly preferably 80% or less, and most preferably 50% or less. Usually, it is 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 including a pressure-sensitive adhesive layer comprising the water-dispersed pressure-sensitive adhesive composition effectively prevent the generation of bubbles and distortion at high temperatures and high humidity. can do. 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, so that the water-dispersed pressure-sensitive adhesive composition having high adhesion at low cost, such as An adhesive film provided with an adhesive layer made of a water-dispersed 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, 92 parts of butyl acrylate, 6 parts of methacrylic acid, 2 parts of mono [poly (propylene oxide) methacrylate] phosphate (average degree of polymerization of propylene oxide of about 5.0), 3-methacryloyloxypropyl-trimethoxysilane 0.03 parts (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed to prepare a mixture of reaction components. Next, 46.8 g of reactive emulsifier Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.) and 346 g of ion-exchanged water are added to 388 g of the prepared reaction component mixture, and a homogenizer (manufactured by Tokushu Kika Co., Ltd.) is used. The mixture was stirred and forcedly emulsified at 5000 (1 / min) for 5 minutes to prepare a monomer pre-emulsion.
(Preparation of water-dispersed copolymer emulsion)
156 g of the monomer pre-emulsion prepared above and 219 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. 023 g (0.03 part with respect to 100 parts of solid content of the charged monomer pre-emulsion) was added, and polymerization was performed at 65 ° C. for 2.5 hours. Next, 0.217 g of ammonium persulfate (0.07 part with respect to 100 parts of the solid content of the remaining monomer pre-emulsion) was added to 625 g of the remaining monomer pre-emulsion, and this was added dropwise to the reaction vessel over 3 hours. Thereafter, polymerization was performed at 70 ° C. for 3 hours while purging with nitrogen 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 a carbodiimide-based crosslinking agent (Carbodilite V-04, water-soluble type, manufactured by Nisshinbo Co., Ltd.) 0.1 part was added to 100 parts of the solid content of the emulsion (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 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 0.25. A primer solution diluted to a weight percent was prepared. Next, this primer solution was applied to one side of a polarizing film using a wire bar # 5, and dried by heating at 40 ° C. for 2 minutes to provide an undercoat layer.

In addition, said polarizing film was produced by extending | stretching a polyvinyl alcohol film in iodine aqueous solution, drying, and adhere | attaching a triacetyl cellulose film as a transparent protective film on both sides of this polarizer.
Next, this polarizing film is laminated on the retardation film (NAZ- # 195-0.3, manufactured by Nitto Denko Corporation) so that the surface on which the undercoat layer is not provided and the retardation film are bonded together. Laminated. 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, 0.3 part of a carbodiimide-based crosslinking agent (carbodilite V-04) was added instead of 0.1 part of the carbodiimide-based crosslinking agent (carbodilite V-04). Except for the above, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, and then a pressure-sensitive adhesive optical film was produced.

Example 3
(Preparation of monomer pre-emulsion)
In a container, 88 parts of butyl acrylate, 5 parts of acrylic acid, 5 parts of cyclohexyl methacrylate, 2 parts of mono [poly (propylene oxide) methacrylate] phosphate (average polymerization degree of propylene oxide of about 5.0), 3-methacryloyl 0.03 part of oxypropyl-trimethoxysilane (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed to prepare a mixture of reaction components. Next, 46.8 g of reactive emulsifier Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.) and 346 g of ion-exchanged water are added to 388 g of the prepared reaction component mixture, and a homogenizer (manufactured by Tokushu Kika Co., Ltd.) is used. The mixture was stirred and forcedly emulsified at 5000 (1 / min) for 5 minutes to prepare a monomer pre-emulsion.
(Preparation of water-dispersed copolymer emulsion)
78 g of the monomer pre-emulsion prepared above and 219 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. 004 g (0.01 parts with respect to 100 parts of solid content of the charged monomer pre-emulsion) was added, and polymerization was performed at 65 ° C. for 2.5 hours. Next, 0.244 g of ammonium persulfate (0.07 parts with respect to 100 parts of the solid content of the remaining monomer pre-emulsion) was added to 702.5 g of the remaining monomer pre-emulsion, and this was added to the reaction vessel over 3 hours. Then, the mixture was polymerized at 75 ° C. for 3 hours while substituting with nitrogen 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 is cooled to room temperature, 10% aqueous ammonia is added to adjust the pH to 8, and the carbodiimide-based crosslinking agent (carbodilite V-04) is added to the solid content of the emulsion (water-dispersed co-polymer). A water-dispersed pressure-sensitive adhesive composition was prepared by adding 0.5 part to 100 parts of coalescence.
(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 heat-treated at 100 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 23 μm.

Next, the pressure-sensitive adhesive layer was laminated on the undercoat layer of the same optical film as in Example 1 to produce a pressure-sensitive adhesive optical film (see FIG. 2).
Example 4
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, in place of 0.5 part of carbodiimide-based crosslinking agent (carbodilite V-04), 1 part of carbodiimide-based crosslinking agent (carbodilite V-04) was added. Then, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3, and then a pressure-sensitive adhesive optical film was produced.

Example 5
In the preparation of the water-dispersed copolymer emulsion in Example 3, ammonium persulfate was used instead of 0.244 g of ammonium persulfate in the drop polymerization (0.07 parts relative to the solid content of 100 parts of the remaining monomer pre-emulsion). A water-dispersed copolymer emulsion (water dispersion) in the same manner as in Example 3 except that 0.175 g (0.05 parts with respect to the solid content of 100 parts of the remaining monomer pre-emulsion) was added. Then, a water-dispersed pressure-sensitive adhesive composition was prepared, and subsequently, a pressure-sensitive adhesive optical film was produced.

Example 6
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, in place of 0.5 part of carbodiimide-based crosslinking agent (carbodilite V-04), 1 part of carbodiimide-based crosslinking agent (carbodilite V-04) was added. Then, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3, and then a pressure-sensitive adhesive optical film was produced.

Example 7
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, in place of 0.5 part of carbodiimide-based crosslinking agent (carbodilite V-04), 2 parts of carbodiimide-based crosslinking agent (carbodilite V-04) were added. Then, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3, and then a pressure-sensitive adhesive optical film was produced.

Example 8
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, in place of 0.5 part of carbodiimide-based crosslinking agent (carbodilite V-04), 3 parts of carbodiimide-based crosslinking agent (carbodilite V-04) was added. Then, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3, and then a pressure-sensitive adhesive optical film was produced.

Example 9
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, instead of 0.5 part of carbodiimide-based crosslinking agent (carbodilite V-04), carbodiimide-based crosslinking agent (carbodilite E-04, emulsion type, Nisshinbo Co., Ltd.) Product) A water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3 except that 1 part was added, and then a pressure-sensitive adhesive optical film was prepared.

Example 10
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, instead of 0.5 part of carbodiimide-based crosslinking agent (carbodilite V-04), carbodiimide-based crosslinking agent (carbodilite E-04, emulsion type, Nisshinbo Co., Ltd.) Product) A water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3 except that 0.5 part was added, and then a pressure-sensitive adhesive optical film was produced.

Example 11
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, instead of 0.5 part of carbodiimide-based crosslinking agent (carbodilite V-04), carbodiimide-based crosslinking agent (carbodilite E-04, emulsion type, Nisshinbo Co., Ltd.) Product) A water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3 except that 2 parts were added, and then a pressure-sensitive adhesive optical film was prepared.

Comparative Example 1
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 carbodiimide-based crosslinking agent was added. A mold optical film was prepared.
Comparative Example 2
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3 except that no carbodiimide-based crosslinking agent was added. A mold optical film was prepared.

Comparative Example 3
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, 0.0005 part of a carbodiimide-based crosslinking agent (carbodilite V-04) was added instead of 0.1 part of the carbodiimide-based crosslinking agent (carbodilite V-04). Except for the above, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3, and then a pressure-sensitive adhesive optical film was produced.

Comparative Example 4
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, 0.001 part of carbodiimide-based crosslinking agent (carbodilite V-04) was added instead of 0.5 part of carbodiimide-based crosslinking agent (carbodilite V-04). Except for the above, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3, and then a pressure-sensitive adhesive optical film was produced.

Comparative Example 5
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, 0.05 part of carbodiimide-based crosslinking agent (carbodilite V-04) was added instead of 0.5 part of carbodiimide-based crosslinking agent (carbodilite V-04). Except for the above, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3, and then a pressure-sensitive adhesive optical film was produced.

Comparative Example 6
In the preparation of the water-dispersed pressure-sensitive adhesive composition in Example 3, in place of 0.5 part of carbodiimide-based crosslinking agent (carbodilite V-04), 5 parts of carbodiimide-based crosslinking agent (carbodilite V-04) was added. Then, a water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 3, and then a pressure-sensitive adhesive optical film was produced.

(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 the ethyl acetate adhering to the Teflon sheet (registered trademark) was wiped off, 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): Teflon sheet (registered trademark) and octopus yarn total weight (tare weight)
B (g): Teflon sheet (registered trademark) and octopus yarn and water-dispersed adhesive composition immersed in ethyl acetate, total weight before drying C (g): Teflon sheet (registered trademark) and octopus yarn, Table 1 shows the total weight after immersion in ethyl acetate with the water-dispersed pressure-sensitive adhesive composition and drying.

3) Glass adhesiveness The adhesive optical film obtained by each Example and each comparative example was cut | disconnected to width 25mm, this was stuck on a glass plate (Corning # 1737, Corning Co., Ltd. product), and 2 kg The rubber 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 measured for 90 ° peel adhesive strength (peel rate 10 mm / min). (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 thick glass plate (Corning # 1737, manufactured by Corning). 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 ×: 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 is about 5.0), manufactured by Rhodia Nikka Co., Ltd.)
KBM-503: 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
HS-10: Reactive emulsifier Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.)
V-04: Carbodiimide type crosslinking agent (Carbodilite V-04, water-soluble type, manufactured by Nisshinbo Co., Ltd.)
E-04: Carbodiimide crosslinking agent (Carbodilite E-04, emulsion type, manufactured by Nisshinbo 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)

Provided with a pressure-sensitive adhesive layer comprising a water-dispersed pressure-sensitive adhesive composition,
The water-dispersed pressure-sensitive adhesive composition is
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 crosslinking agent having reactivity with a carboxyl group ,
The crosslinking agent is a compound having a carbodiimide group,
The blending ratio of the (meth) acrylic acid alkyl ester is 60 to 98 parts by weight with respect to 100 parts by weight of the reaction component,
The blending ratio of the (meth) acrylic acid is 0.5 to 15 parts by weight with respect to 100 parts by weight of the reaction component,
The blending ratio of the phosphate group-containing vinyl monomer is 0.5 to 20 parts by weight with respect to 100 parts by weight of the reaction component,
The blending ratio of the alkoxysilyl group-containing vinyl monomer is 0.001 to 1 part by weight with respect to 100 parts by weight of the reaction component,
The phosphate group concentration of the phosphate group-containing vinyl monomer is 0.01 to 0.45 mmol / g in the reaction component,
The blending ratio of the crosslinking agent is 0.07 to 4 parts by weight with respect to 100 parts by weight of the water-dispersed copolymer,
Pressure-sensitive adhesive layer comprising the aqueous dispersion type pressure-sensitive adhesive composition is characterized in that the elongation at 90 ° C. by the following test, 200% or less, pressure-sensitive adhesive optical film.
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 2 hours of suspension. And the elongation is calculated by the following formula.
Elongation (%) = (L ₁ −L ₀ ) / L ₀ × 100 The pressure-sensitive adhesive optical film 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.   The said reaction component contains the (meth) acrylic-acid alicyclic hydrocarbon ester which has a C6 or more alicyclic hydrocarbon group further, It is characterized by the above-mentioned. Adhesive optical film.

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