JP5470217B2 - Optical water-dispersed adhesive, optical adhesive layer, adhesive optical film, and image display device - Google Patents

Description

  The present invention relates to an optical water-dispersed pressure-sensitive adhesive. The present invention also relates to an optical pressure-sensitive adhesive layer formed from the water-dispersed pressure-sensitive adhesive, and a pressure-sensitive adhesive optical film in which the pressure-sensitive adhesive layer is laminated on an optical film. Furthermore, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device and a PDP using the adhesive optical film. As the optical film, a polarizing plate, a retardation plate, a front plate, an optical compensation film, a brightness enhancement film, and a laminate of these can be used.

  In liquid crystal display devices, it is indispensable to dispose polarizing elements on both sides of the liquid crystal cell because of its image forming method. In general, polarizing plates with a transparent protective film bonded to one or both sides of a polarizer are attached. Has been. In addition to polarizing plates, various optical elements have been used for liquid crystal panels in order to improve the display quality of displays. For example, a retardation plate for preventing coloring, a viewing angle widening film for improving the viewing angle of a liquid crystal display, and a brightness enhancement film for increasing the contrast of the display are used. These films are collectively called optical films.

  When sticking the optical film on a liquid crystal cell, an adhesive is usually used. In addition, the adhesion between the optical film and the liquid crystal cell, or the optical film is usually in close contact with each other using an adhesive in order to reduce the loss of light. In such a case, an adhesive optical film in which an adhesive is previously provided as an adhesive layer on one side of the optical film has advantages such as not requiring a drying step to fix the optical film. Generally used.

  As the pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive optical film, an organic solvent-type pressure-sensitive adhesive has been mainly used since it has excellent durability in a heated or humidified heat environment. In recent years, development of solventless pressure-sensitive adhesives that do not use an organic solvent has been actively performed from the viewpoint of reducing the burden on the global environment and improving work stability.

  As the solventless adhesive, for example, a water-dispersed adhesive in which an adhesive polymer component is dispersed in water using water as a dispersion medium has been proposed. For example, a pressure-sensitive adhesive or an adhesive using an aqueous emulsion containing an emulsion whose particle diameter is controlled within a specific range has been proposed (Patent Documents 1 to 3). It is described that the pressure-sensitive adhesive or adhesive is excellent in water resistance and water whitening resistance. Further, an optical water-spraying pressure-sensitive adhesive composition in which a clay mineral and a dispersion component are blended with a water-dispersed acrylic copolymer having a specific composition has been proposed (Patent Document 4). According to the water-scattering pressure-sensitive adhesive composition, it is described that an adhesive optical film having a small haze value and good transparency can be obtained.

Japanese Patent Laid-Open No. 09-278837 JP 2000-109784 A JP 2004-123961 A JP 2010-006896 A

  The liquid crystal display device is required to have an image appearance, and the liquid crystal display device is required to have high contrast related to white display and black display. Various members have been developed to increase the contrast of liquid crystal display devices. Therefore, it is required that members used in the liquid crystal display device, for example, the pressure-sensitive adhesive layer, do not hinder high contrast.

  In order not to inhibit the increase in contrast, it is desirable that the member used in the liquid crystal display device does not cause depolarization. In particular, in a liquid crystal display device, a member on the inner side of two polarizing plates (transparent protective film on the liquid crystal cell side, a pressure-sensitive adhesive layer, a liquid crystal cell in the polarizing plate) disposed on both sides of the liquid crystal cell via an adhesive layer Is required not to cause depolarization.

  However, in a water-dispersed pressure-sensitive adhesive using an aqueous emulsion, emulsion particles accumulate by drying to form a pressure-sensitive adhesive layer. For this reason, it has been found that the adhesive layer has many polymer particle interfaces, and scattering occurs at the polymer particle interfaces, resulting in depolarization. Conventionally, when a polarizing plate or a liquid crystal cell having a low contrast is used, depolarization is particularly a problem even when an adhesive layer formed using a water-dispersed adhesive is used as the adhesive layer of the polarizing plate. I didn't. However, with the development of high contrast as described above, various developments have been made for polarizing plates and liquid crystal cells. As a result, pressure-sensitive adhesive layers formed using conventional water-dispersed pressure-sensitive adhesives can be used for high contrast. When applied to a polarizing plate or the like having a high degree of polarization, the conventional water-dispersed pressure-sensitive adhesive causes depolarization, resulting in a problem of lowering the contrast.

  The pressure-sensitive adhesive layer formed from the water-dispersed pressure-sensitive adhesives of Patent Documents 1 to 3 has effects such as a decrease in the degree of physical property change and white turbidity when immersed in water. However, the pressure-sensitive adhesive layer formed from the water-dispersed pressure-sensitive adhesives disclosed in Patent Documents 1 to 3 cannot reduce the depolarization property and make it possible to increase the contrast of the pressure-sensitive adhesive optical film. Moreover, in patent document 4, the haze value is small and the adhesive layer with a large transmittance | permeability value is shown, and the transparency of an adhesive layer is ensured. However, the haze value is not an index for measuring the transmittance of polarized light, and just because the haze value is small, depolarization cannot be reduced.

  The present invention is also an optical water-dispersed pressure-sensitive adhesive, and the optical pressure-sensitive adhesive layer formed from the optical water-dispersed pressure-sensitive adhesive is applied to a polarizing plate having a high degree of polarization for high contrast. An object of the present invention is to provide an optical water-dispersed pressure-sensitive adhesive that can reduce depolarization. Another object of the present invention is to provide an optical pressure-sensitive adhesive layer formed from the optical water-dispersed pressure-sensitive adhesive.

  Another object of the present invention is to provide a pressure-sensitive adhesive optical film in which the optical pressure-sensitive adhesive layer is laminated on at least one side of the optical film. A further object of the present invention is to provide an image display device using the adhesive optical film.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the following optically water-dispersed pressure-sensitive adhesive, and have completed the present invention.

That is, the present invention is an optically water-dispersed pressure-sensitive adhesive comprising an aqueous dispersion containing a water-dispersible base polymer (A) and a film-forming auxiliary (B) and / or a plasticizer (C),
Optical water characterized in that the ratio of the film forming aid (B) and / or the plasticizer (C) is 0.1 to 15 parts by weight with respect to 100 parts by weight of the optical water-dispersed pressure-sensitive adhesive. The present invention relates to a dispersion type adhesive.

  In the optical water-dispersed pressure-sensitive adhesive, a high-boiling solvent having a boiling point of less than 110 to 230 ° C. can be used as the film forming aid (B).

In the optical water-dispersed pressure-sensitive adhesive, the film-forming aid (B) is, for example,
Formula _{^{(1): R 1 - (}} CO) m - (OA) n -OR 2
(Wherein R ¹ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R ² is a hydrocarbon group having 1 to 10 carbon atoms, A is an alkylene group having 2 or 3 carbon atoms, n is an integer of 1 to 60, and m = 0 or 1. However, R ¹ is a hydrogen atom and m = 1, and a glycol ether solvent represented by:
General formula (2): R < ³ > -OH
(In the formula, R ³ is a hydrocarbon group having 4 to 12 carbon atoms.) It is possible to preferably use at least one selected from alcohol solvents represented by:

  In the optical water-dispersed pressure-sensitive adhesive, the plasticizer (C) may be a compound having a boiling point of 230 to 420 ° C.

  In the optical water-dispersed pressure-sensitive adhesive, for example, an ester plasticizer obtained from a carboxylic acid compound and an alcohol compound can be preferably used as the plasticizer (C). Moreover, as said ester plasticizer, the polyvalent carboxylic acid polyvalent ester obtained from polyhydric carboxylic acid and monohydric alcohol can be used preferably, for example. As the ester plasticizer, for example, mono- and dialkyl esters of 2,2,4-trimethyl-1,3-pentanediol (wherein the alkyl group has 4 to 8 carbon atoms) can be preferably used. .

  In the optically water-dispersible pressure-sensitive adhesive, the water-dispersed base polymer (A) is 60 to 99. (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 3 to 14 carbon atoms. An acrylic polymer obtained by emulsion polymerization of a monomer component containing 9% by weight and 0.1 to 10% by weight of a carboxyl group-containing monomer in the presence of a radical polymerization initiator and a surfactant is preferred.

  The monomer component contains a copolymerization monomer in a proportion of 39% by weight or less, and the copolymerization monomer contains a high Tg monomer that makes the glass transition temperature (Tg) of the homopolymer 50 ° C. or more. It is preferable. As the high Tg monomer, for example, a methacrylic acid alkyl ester having an alkyl group having 1 or 2 carbon atoms and / or a styrene monomer can be used.

  The present invention also relates to an optical pressure-sensitive adhesive layer, which is formed by applying the optical water-dispersed pressure-sensitive adhesive and drying it.

  The present invention also relates to a pressure-sensitive adhesive optical film, wherein the optical pressure-sensitive adhesive layer is laminated on at least one side of the optical film.

Examples of the adhesive optical film include an adhesive polarizing plate in which the optical adhesive layer is laminated on one side of a polarizing plate provided with a transparent protective film on at least one side of a polarizer. Difference between the degree of polarization (P1) of the plate and the degree of polarization (P2) of the adhesive polarizing plate ( P1-P2 )
It is preferable that the depolarization value represented by this satisfies 0.015 or less.

  The present invention also relates to an image display device characterized by using at least one adhesive optical film.

  In the water-dispersed pressure-sensitive adhesive according to the water-dispersed liquid containing the water-dispersed base polymer (A), the emulsion particles according to the water-dispersed base polymer (A) include polymer particles and polymer particles that form the main body of the emulsion particles. There are components (surfactant, water-soluble component, water, etc.) that exist between the interfaces. The scattering of light generated in the pressure-sensitive adhesive layer formed by the water-dispersed pressure-sensitive adhesive is mainly caused by the difference in refractive index between the polymer particles in the emulsion particles and the components existing between the interfaces of the polymer particles. That is, light scattering occurring in the pressure-sensitive adhesive layer increases as the ratio of the components existing between the interfaces of the polymer particles increases, and depolarization occurs due to the light scattering. Therefore, it is preferable that the ratio of the component existing between the interfaces of the polymer particles is small with respect to the ratio of the polymer particles related to the emulsion particles. On the other hand, since the component existing between the interfaces of the polymer particles is a component that stabilizes the emulsion particles, if the amount is too small, the emulsion particles become unstable and exist as very large and distorted aggregated particles. There is a risk of seriously damaging the appearance.

  In the present invention, in order to reduce the depolarization of the pressure-sensitive adhesive layer, from the above viewpoint, the film forming aid (B) is added to the water-dispersed pressure-sensitive adhesive according to the water dispersion containing the water-dispersed base polymer (A). And / or a plasticizer (C). When film forming aid (B) and / or plasticizer (C) is blended with water-dispersed pressure-sensitive adhesive, it exists at the interface of emulsion particles when the pressure-sensitive adhesive layer is formed by the water-dispersed pressure-sensitive adhesive. The polymer body to be plasticized can be plasticized. As a result, while ensuring the stability of the emulsion particles according to the water-dispersed base polymer (A) in the water-dispersed pressure-sensitive adhesive, in forming the pressure-sensitive adhesive layer with the water-dispersed pressure-sensitive adhesive, The adhesion between the emulsion particles is improved, the ratio between the interfaces of the polymer particles is reduced, and a pressure-sensitive adhesive layer in which depolarization is suppressed can be formed.

  In addition, since the film-forming property is improved by plasticizing the polymer body as described above by blending the film-forming auxiliary (B) and / or the plasticizer (C) with the water-dispersed pressure-sensitive adhesive, the pressure-sensitive adhesive The depolarization property can be controlled to be small without increasing the amount of drying heat when forming the layer.

  The optical water-dispersed pressure-sensitive adhesive of the present invention comprises a water-dispersed base polymer (A), a film forming aid (B) and / or a plasticizer (C), and the water-dispersed The mold pressure-sensitive adhesive is prepared by blending the film-forming auxiliary (B) and / or the plasticizer (C) with the water dispersion (water-dispersed pressure-sensitive adhesive) containing the water-dispersible base polymer (A). can do.

  Various adhesives can be used as the water-dispersed pressure-sensitive adhesive related to the aqueous dispersion containing the water-dispersed base polymer (A). For example, rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives. Agents, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, cellulose adhesives, and the like. An adhesive base polymer (A) or a dispersing means is selected according to the type of the adhesive. Methods for obtaining water-dispersed pressure-sensitive adhesives include emulsion polymerization of various monomer components, solution polymerization of various monomer components, followed by phase inversion by adding water to the aqueous dispersion, and various resins having surface activity. For example, a forced dispersion method of dispersing in an agent or the like can be mentioned.

  Among the above-mentioned pressure-sensitive adhesives, the present invention is excellent in optical transparency, exhibits appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and is excellent in weather resistance, heat resistance, and the like. A system adhesive is preferably used.

  The water-dispersed acrylic pressure-sensitive adhesive was obtained, for example, by emulsion polymerization of a monomer component mainly composed of (meth) acrylic acid alkyl ester in water in the presence of a radical polymerization initiator and a surfactant. A water-dispersed pressure-sensitive adhesive containing emulsion particles containing an acrylic polymer is preferably used. The (meth) acrylic acid alkyl ester refers to an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester, and (meth) in the present invention has the same meaning.

  Examples of the monomer component include 60 to 99.9% by weight of a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 3 to 14 carbon atoms and 0.1 to 10% of a carboxyl group-containing monomer. Monomer components containing% by weight are preferred.

  The alkyl group of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 3 to 14 carbon atoms may be either linear or branched. Examples of the linear or branched alkyl group having 4 to 14 carbon atoms include n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, t-butyl group, pentyl group, and neopentyl. Group, isoamyl group, hexyl group, heptyl group, 2-ethylhexyl group, isooctyl group, nonyl group, isononyl group, decyl group, isodecyl group, dodecyl group, tridecyl group, tetradecyl group, and the like. Among these, (meth) acrylic acid alkyl esters having 3 to 9 carbon atoms in the alkyl group such as n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and n-octyl (meth) acrylate. Is preferred.

  The (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 3 to 14 carbon atoms is a main component for imparting tackiness to the acrylic polymer, and is 60 to 60% based on the total amount of monomer components. Contains 99.9% by weight. The proportion of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 3 to 14 carbon atoms is preferably 70 to 99% by weight, more preferably 70 to 95% by weight.

  Examples of the carboxyl group-containing monomer include those having a radical polymerizable unsaturated double bond such as a carboxyl group and a (meth) acryloyl group or a vinyl group. For example, (meth) acrylic acid, itaconic acid, maleic acid, fumar Examples include acids, crotonic acid, carboxyethyl acrylate, carboxypentyl acrylate, and the like. Used to improve the adhesion of the carboxyl group-containing monomer and pressure-sensitive adhesive layer and to provide stability to the emulsion.

  By setting the proportion of the carboxyl group-containing monomer to 0.1% by weight or more, mechanical stability can be imparted to the emulsion, and generation of aggregates when the emulsion is sheared can be suppressed. Moreover, it is preferable to set it as 10 weight% or less in order to suppress the water solubility of an adhesive layer and to satisfy humidification durability. The carboxyl group-containing monomer is 0.1 to 10% by weight based on the total amount of the monomer components. The proportion of the carboxyl group-containing monomer is preferably 0.5 to 7% by weight, and more preferably 1 to 5% by weight.

  In addition to the monomers exemplified above, the monomer component forming the acrylic polymer includes stabilization of emulsion, improvement of adhesion of the adhesive layer to a substrate such as an optical film, and initial adhesion to an adherend. One or more kinds of copolymerization monomers having a polymerizable functional group related to an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be introduced by copolymerization for the purpose of improving the property. The copolymerization monomer can be contained in an amount of 39% by weight or less based on the total amount of the monomer components.

  As the copolymerization monomer, for example, a high Tg monomer having a glass transition temperature (Tg) of a homopolymer of 50 ° C. or higher is preferable because the cohesive force of the pressure-sensitive adhesive layer can be improved. Examples of the high Tg monomer include methacrylic acid alkyl esters having an alkyl group having 1 or 2 carbon atoms, and specific examples include methyl methacrylate and ethyl methacrylate. Examples of the high Tg monomer include (meth) acrylic acid aryl esters such as cyclohexyl methacrylate and isobornyl (meth) acrylate; (meth) acrylic acid such as benzyl (meth) acrylate and phenyl (meth) acrylate. Aromatic hydrocarbon ester; styrene monomers such as styrene and α-methylstyrene. Among these, methyl methacrylate is preferable. The glass transition temperature (Tg) of the homopolymer is the theoretical glass transition temperature used in the FOX equation.

  The proportion of the high Tg monomer is preferably 0.1 to 39% by weight based on the total amount of monomer components. By setting the ratio of the high Tg monomer to 0.1% by weight or more, suitable cohesive force can be imparted to the pressure-sensitive adhesive layer, and foaming of the pressure-sensitive adhesive layer in a high-temperature environment is suppressed, and heat durability is satisfied. This is preferable. Moreover, by setting it as 39 weight% or less, it can suppress that an adhesive layer becomes hard too much, and it is preferable in order to suppress the peeling in a high temperature and high humidity environment, and to satisfy heating and humidification durability. The proportion of the high Tg monomer is more preferably 1 to 30% by weight, and further preferably 5 to 20% by weight.

  Specific examples of the copolymerizable monomer are not particularly limited, and examples thereof include acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; (meth) acrylic acid alkyl esters other than those described above; for example, vinyl acetate and propion. Vinyl esters such as vinyl acid; epoxy group-containing monomers such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; for example, 2-hydroxyethyl (meth) acrylate, 2-methacrylic acid 2- Hydroxyl group-containing monomers such as hydroxypropyl and 4-hydroxybutyl (meth) acrylate; for example, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl ( (Meth) acrylamide, N-butyl (meth) aqua Luamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, (meth) acryloylmorpholine, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, (meth) acrylic Nitrogen atom-containing monomers such as t-butylaminoethyl acid; for example, alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile Functional monomers such as 2-methacryloyloxyethyl isocyanate; olefin monomers such as ethylene, propylene, isoprene, butadiene and isobutylene; vinyl ethers such as vinyl ether; Nomers; for example, halogen atom-containing 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 other N-vinylcarboxylic acid amides.

  Examples of copolymerizable monomers include maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; for example, N-methylitaconimide, N-ethylitaconimide, N -Itacone imide monomers such as butyl itaconimide, N-octyl itacon imide, N-2-ethylhexyl itacon imide, N- cyclohexyl itacon imide, N- lauryl itacon imide; for example, N- (meth) acryloyloxymethylene succinimide, N- Succinimide monomers such as (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide; for example, styrene sulfonic acid, Examples include sulfonic acid group-containing monomers such as aryl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloyloxynaphthalene sulfonic acid. .

Examples of the copolymerizable monomer include a phosphate group-containing monomer. Examples of the phosphate group-containing monomer include the following general formula (1):

(In General Formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 1 to 4 carbon atoms, m represents an integer of 2 or more, and M ¹ and M ² are each independently selected. Represents a hydrogen atom or a cation). The phosphoric acid group containing monomer represented by this is mentioned.

  In general formula (1), m is 2 or more, preferably 4 or more and usually 40 or less, and m represents the degree of polymerization of the oxyalkylene group. Examples of the polyoxyalkylene group include a polyoxyethylene group, a polyoxypropylene group, and the like, and these polyoxyalkylene groups may be random, block, or graft units. In addition, the cation according to the salt of the phosphate group is not particularly limited, for example, an alkali metal such as sodium or potassium, for example, an inorganic cation such as an alkaline earth metal such as calcium or magnesium, for example, a quaternary amine And organic cations.

  In addition, as the copolymerizable monomer, for example, glycol-based acrylic ester monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate Other examples include, for example, tetrahydrofurfuryl (meth) acrylate, a heterocyclic ring such as fluorine (meth) acrylate, and an acrylate monomer containing a halogen atom.

  Furthermore, a silicone type unsaturated monomer is mentioned as a copolymerizable monomer. Silicone unsaturated monomers include silicone (meth) acrylate monomers and silicone 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) acryloyloxyalkyl-trialkoxysilane such as (meth) acryloyloxypropyl-triisopropoxysilane, 3- (meth) acryloyloxypropyl-tributoxysilane; Acryloyloxymethyl-methyldimethoxysilane, (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-methyldiiso Propoxysilane, 3- (meth) acryloyloxypropyl-methyldibutoxysilane, 3- (meth) acryloyloxypropyl-ethyldimethoxysilane, 3- (meth) acryloyloxypropyl- Tildiethoxysilane, 3- (meth) acryloyloxypropyl-ethyldipropoxysilane, 3- (meth) acryloyloxypropyl-ethyldiisopropoxysilane, 3- (meth) acryloyloxypropyl-ethyldibutoxysilane, 3- (Meth) acryloyloxypropyl-propyldimethoxysilane, (meth) acryloyloxyalkyl-alkyldialkoxysilane such as 3- (meth) acryloyloxypropyl-propyldiethoxysilane, and (meth) acryloyloxyalkyl- corresponding to these Examples thereof include dialkyl (mono) alkoxysilane. 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.

  Furthermore, a polyfunctional monomer can be used as the copolymerizable monomer for adjusting the gel fraction of the water-dispersed pressure-sensitive adhesive. Examples of the polyfunctional monomer include compounds having two or more unsaturated double bonds such as a (meth) acryloyl group and a vinyl group. For example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetraethylene glycol di (meth) acrylate, etc. (mono or poly) In addition to (mono or poly) alkylene glycol di (meth) acrylates such as ethylene glycol di (meth) acrylate and (mono or poly) propylene glycol di (meth) acrylate such as propylene glycol di (meth) acrylate, neopentyl glycol Di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate Esterified products of (meth) acrylic acid and polyhydric alcohols such as pentaerythritol tri (meth) acrylate and dipentaerythritol hexa (meth) acrylate; polyfunctional vinyl compounds such as divinylbenzene; allyl (meth) acrylate, (meth ) A compound having a reactive unsaturated double bond such as vinyl acrylate. In addition, as a polyfunctional monomer, polyester (meta) having two or more unsaturated double bonds such as (meth) acryloyl group and vinyl group as functional groups similar to the monomer component is added to a skeleton such as polyester, epoxy, and urethane. ) Acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, and the like can also be used.

  Among these copolymerization monomers, from the viewpoint of stabilizing the aqueous dispersion (emulsion) and ensuring adhesion to the glass panel that is the adherend of the pressure-sensitive adhesive layer formed from the emulsion, it contains a phosphate group. Monomers and silicone unsaturated monomers are preferably used.

  Moreover, the blending ratio of the copolymerizable monomer can be appropriately selected depending on the type of each copolymerizable monomer. In the case of a phosphate group-containing monomer, the proportion is preferably 0.5 to 5% by weight relative to the total amount of the monomer component, and in the case of a silicone-based unsaturated monomer, the proportion is relative to the total amount of the monomer component. 0.005 to 0.2% by weight is preferable.

  In the case where the copolymerizable monomer other than the alkoxysilyl group-containing monomer and the phosphate group-containing monomer is a monofunctional monomer, the proportion thereof is such that the viscosity of the emulsion does not become too high, and the monomer component is not stable from the viewpoint of emulsion stability. The total amount is preferably 20% by weight or less, more preferably 10% by weight or less, and further preferably 5% by weight or less. When the copolymerizable monomer is a polyfunctional monomer, the proportion is preferably 5% by weight or less, more preferably 3% by weight, based on the total amount of monomer components of the acrylic polymer, from the viewpoint of emulsion stability. Hereinafter, it is further preferably 1% by weight or less.

  Emulsion polymerization of the monomer component is performed by emulsion polymerization after emulsifying the monomer component in water by a conventional method. Thus, an aqueous dispersion (an emulsion containing emulsion particles) containing an acrylic polymer as a base polymer is prepared. In emulsion polymerization, for example, a surfactant (emulsifier), a radical polymerization initiator, and a chain transfer agent, if necessary, are appropriately blended together with the monomer components described above. 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 and the monomer emulsion dropping method, continuous dropping or divided dropping is appropriately selected. These methods can be appropriately combined. Although reaction conditions etc. are selected suitably, it is preferable that polymerization temperature is about 40-95 degreeC, for example, and it is preferable that polymerization time is about 30 minutes-about 24 hours.

  The surfactant (emulsifier) used for emulsion polymerization is not particularly limited, and various surfactants usually used for emulsion polymerization are used. As the surfactant, for example, an anionic surfactant or a nonionic surfactant is used. Specific examples of anionic surfactants include higher fatty acid salts such as sodium oleate; alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate; alkyl sulfate salts such as sodium lauryl sulfate and ammonium lauryl sulfate; polyoxyethylene lauryl Polyoxyethylene alkyl ether sulfate salts such as sodium ether sulfate; Polyoxyethylene alkyl aryl ether sulfate salts such as polyoxyethylene nonylphenyl ether sodium sulfate; Sodium monooctylsulfosuccinate, sodium dioctylsulfosuccinate, polyoxyethylene laurylsulfosuccinate Alkylsulfosuccinic acid ester salts such as sodium acid salt and derivatives thereof; It can be exemplified sodium naphthalene sulfonate formalin condensate; ether sulfates. Specific examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyethylene alkyl such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether Sorbitan monolaurate, sorbitan monostearate, sorbitan higher fatty acid esters such as sorbitan trioleate; polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; polyoxyethylene monolaurate; Polyoxyethylene higher fatty acid esters such as polyoxyethylene monostearate; oleic acid monoglyceride, stearic acid monoglyceride, etc. Can be exemplified polyoxyethylene-polyoxypropylene block copolymers, polyoxyethylene distyrenated phenyl ether; glycerol higher fatty acid esters.

  In addition to the non-reactive surfactant, a reactive surfactant having a radical polymerizable functional group related to an ethylenically unsaturated double bond can be used as the surfactant. As the reactive surfactant, a radical polymerizable surfactant obtained by introducing a radical polymerizable functional group (radical reactive group) such as propenyl group or allyl ether group into the anionic surfactant or nonionic surfactant. Agents and the like. These surfactants are used alone or in combination as appropriate. Among these surfactants, a radical polymerizable surfactant having a radical polymerizable functional group is preferably used from the viewpoint of the stability of the aqueous dispersion and the durability of the pressure-sensitive adhesive layer.

  Specific examples of the anionic reactive surfactant include alkyl ethers (for example, Aqualon KH-05, KH-10, KH-20, manufactured by Asahi Denka Kogyo Co., Ltd. Adekaria soap SR-10N, SR-20N, Latemu PD-104, etc. manufactured by Kao Corporation); Sulfosuccinic acid ester system (for example, Latemul S-120, S-120A, S-180P manufactured by Kao Corporation) S-180A, Sanyo Chemical Co., Ltd., Eleminol JS-2, etc.); alkyl phenyl ether or alkyl phenyl ester (commercially available products include, for example, Aqualon H-2855A, H-3855B, Daiichi Kogyo Seiyaku Co., Ltd., H-3855C, H-3856, HS-05, HS-10, HS-20, HS-30, BC- (5, BC-10, BC-20, Adeka Soap SDX-222, SDX-223, SDX-232, SDX-233, SDX-259, SE-10N, SE-20N) manufactured by Asahi Denka Kogyo Co., Ltd. ) Acrylate sulfate ester (commercially available products include, for example, Antox MS-60, MS-2N, Sanyo Kasei Kogyo Co., Ltd., Elminol RS-30, etc. manufactured by Nippon Emulsifier Co., Ltd.); For example, H-3330PL manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Adeka Soap PP-70 manufactured by Asahi Denka Kogyo Co., Ltd.). Nonionic reactive surfactants include, for example, alkyl ethers (commercially available products such as Adeka Soap ER-10, ER-20, ER-30, ER-40, Kao Corporation, manufactured by Asahi Denka Kogyo Co., Ltd. Latemul PD-420, PD-430, PD-450, etc.); alkyl phenyl ethers or alkyl phenyl esters (commercially available products include, for example, Aqualon RN-10, RN-20, RN manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) -30, RN-50, Adeka Soap NE-10, NE-20, NE-30, NE-40, etc. manufactured by Asahi Denka Kogyo Co., Ltd.); (meth) acrylate sulfate ester type (commercially available products include, for example, Japan Emulsifiers RMA-564, RMA-568, RMA-1114, etc.).

  The blending ratio of the surfactant is preferably 0.3 to 5 parts by weight with respect to 100 parts by weight of the monomer component. Depending on the blending ratio of the surfactant, adhesion characteristics, polymerization stability, mechanical stability, and the like can be improved. The blending ratio of the surfactant is more preferably 0.3 to 4 parts by weight.

  The radical polymerization initiator is not particularly limited, and a known radical 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, Azo initiators such as 2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride; for example, potassium persulfate, Persulfate-based initiators such as ammonium persulfate; for example, peroxide-based initiators such as benzoyl peroxide, t-butyl hydroperoxide, hydrogen peroxide; for example, substituted ethane-based initiators such as phenyl-substituted ethane; And carbonyl-based initiators such as aromatic carbonyl compounds. These polymerization initiators are suitably used alone or in combination. Moreover, when performing emulsion polymerization, it can be set as the redox-type initiator which uses a reducing agent together with a polymerization initiator depending on necessity. Thereby, it becomes easy to accelerate the emulsion polymerization rate or to perform the emulsion polymerization at a low temperature. Examples of such reducing agents include reducing organic compounds such as metal salts such as ascorbic acid, ersorbic acid, tartaric acid, citric acid, glucose, formaldehyde sulfoxylate; thorium thiosulfate, sodium sulfite, sodium bisulfite, Examples include reducing inorganic compounds such as sodium metabisulfite; ferrous chloride, Rongalite, thiourea dioxide, and the like.

  Further, the blending ratio of the radical polymerization initiator is appropriately selected, and is, for example, about 0.02 to 1 part by weight, preferably 0.02 to 0.5 part by weight, with respect to 100 parts by weight of the monomer component. More preferably, it is 0.08 to 0.3 parts by weight. When the amount is less than 0.02 part by weight, the effect as a radical polymerization initiator may be reduced. When the amount exceeds 1 part by weight, the molecular weight of the acrylic polymer in the aqueous dispersion (polymer emulsion) decreases, and water The durability of the dispersion-type adhesive may be reduced. In the case of a redox initiator, the reducing agent is preferably used in the range of 0.01 to 1 part by weight with respect to 100 parts by weight of the total amount of monomer components.

  The chain transfer agent adjusts the molecular weight of the acrylic polymer 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, 2,3-dimethylcapto-1-propanol, and mercaptopropionic acid esters. These chain transfer agents are appropriately used alone or in combination. Moreover, the mixture ratio of a chain transfer agent is 0.001-0.3 weight part with respect to 100 weight part of monomer components, for example.

  By such emulsion polymerization, it can be prepared as an emulsion containing acrylic polymer particles (containing as emulsion particles). The average particle diameter of such an emulsion type acrylic polymer is adjusted to, for example, 0.05 to 3 μm, preferably 0.05 to 1 μm. If the average particle size is less than 0.05 μm, the viscosity of the water-dispersed pressure-sensitive adhesive may increase. If it is greater than 1 μm, the adhesion between particles may decrease and the cohesive force may decrease.

  Moreover, in order to maintain the dispersion stability of the emulsion, when the acrylic polymer according to the emulsion contains a carboxyl group-containing monomer or the like as a copolymerizable monomer, neutralize the carboxyl group-containing monomer or the like. Is preferred. Neutralization can be performed, for example, with ammonia, alkali metal hydroxide, or the like.

  In general, the emulsion type acrylic polymer of the present invention preferably has a weight average molecular weight of 1,000,000 or more. In particular, those having a weight average molecular weight of 1,000,000 to 4,000,000 are preferable in terms of heat resistance and moisture resistance. When the weight average molecular weight is less than 1,000,000, heat resistance and moisture resistance are lowered, which is not preferable. Moreover, the pressure-sensitive adhesive obtained by emulsion polymerization is preferable because its molecular weight becomes very high due to its polymerization mechanism. However, since the pressure-sensitive adhesive obtained by emulsion polymerization generally has a large gel content and cannot be measured by GPC (gel permeation chromatography), it is often difficult to support the actual measurement regarding molecular weight.

  The film-forming aid (B) is a pressure-sensitive adhesive that does not aggregate in the aqueous dispersion even when added to the water-dispersed pressure-sensitive adhesive that is an aqueous dispersion containing the water-dispersed base polymer (A). In the coating state at the time of forming the layer, it has an effect of temporarily plasticizing the coating film. Moreover, the film-forming auxiliary (B) is preferably one that does not remain in the pressure-sensitive adhesive layer after the coating film is dried to form the pressure-sensitive adhesive layer.

  As such a film forming auxiliary (B), for example, a high boiling point solvent having a boiling point of less than 110 to 230 ° C. can be suitably used. The boiling point of such a high boiling point solvent is preferably 120 to 220 ° C. The boiling point is a measured value under normal pressure (1 atm).

  Further, the film forming aid (B) is preferably a liquid at room temperature (23 ° C.). It is preferable that the film forming aid (B) has a melting point of 30 ° C. or lower. The melting point is a measured value under normal pressure (1 atm).

As the film forming aid (B), for example,
Formula _{^{(1): R 1 - (}} CO) m - (OA) n -OR 2
(Wherein R ¹ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R ² is a hydrocarbon group having 1 to 10 carbon atoms, A is an alkylene group having 2 or 3 carbon atoms, n is an integer of 1 to 60, and m = 0 or 1. Except for the case where R ¹ is a hydrogen atom and m = 1, a glycol ether solvent represented by: Examples of the hydrocarbon group having 1 to 10 carbon atoms according to R ¹ and R ² include linear, branched, or cyclic alkyl groups or alkenyl groups, aromatic groups, and combinations thereof. Can be mentioned. OA is an oxyethylene group or an oxypropylene group, and these may be mixed to form a random body or a block body.

  Specific examples of the glycol ether solvent represented by the general formula (1) include, for example, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol mono Ethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monoisopropyl ether, ethylene glycol mono n-butyl ether, diethylene glycol mono n-butyl ether, triethylene glycol mono n-butyl ether, ethylene glycol monoisobutyl ether, diethylene glycol mono Isobutyl A Ethylene glycol mono n-hexyl ether, diethylene glycol mono n-hexyl ether, ethylene glycol mono 2-ethyl hexyl ether, diethylene glycol mono 2-ethyl hexyl ether, ethylene glycol monoallyl ether, diethylene glycol monoallyl ether, ethylene Glycol monophenyl ether, diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, diethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol monobenzyl ether, ethylene glycol monocyclohexyl ether, polyoxyethylene monophenyl ether, polyethylene glycol monobenzyl ether Ethylene grease such as Solvent monoether solvent: propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol mono n-propyl ether, dipropylene glycol mono n-propyl ether, propylene glycol mono n-butyl ether, dipropylene glycol mono n -Propylene glycol monoether solvents such as butyl ether, propylene glycol monophenyl ether, propylene glycol monocyclohexyl ether; ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethyl And ethylene glycol diether solvents such as lenglycol di n-butyl ether; and propylene glycol diether solvents such as dipropylene glycol dimethyl ether and polyoxypropylene methyl phenyl ether.

  Examples of the glycol ether solvent represented by the general formula (1) include glycol monoether monoester solvents such as propylene glycol methyl ether acetate; polyoxyethylene monoallyl ether, polyoxypropylene monoallyl ether, polyoxy Terminal allylated polyoxyalkylene in which an allyl group is introduced into at least one terminal in polyoxyalkylene glycol such as ethylene diallyl ether, poly (oxyethylene-oxypropylene) monoallyl ether, poly (oxyethylene-oxypropylene) diallyl ether, etc. Solvents: An allyl group is introduced at one end of polyoxyethylene glycol and poly (oxyethylene-oxypropylene) glycol, and the other end is alkyl etherified. Solvents polyoxyethylene glycol ether, and the like were.

  Examples of the glycol ether solvent other than the glycol ether solvent represented by the general formula (1) that can be used as the film forming aid (B) include 1,4-di (2-hydroxyethoxy) benzene, 2,2-bis (4-polyoxyethylene-oxyphenyl) propane, 2,2-bis (4-polyoxypropyleneoxyphenyl) propane, trimethylolpropane tripolyoxyethylene ether, trimethylolpropane tripolyoxypropylene ether, penta Examples include erythritol polyoxyethylene ether.

Moreover, as the film-forming auxiliary (B), the general formula (2): R ³ —OH
(Wherein R ³ is a hydrocarbon group having 4 to 12 carbon atoms). Examples of the hydrocarbon group having 4 to 8 carbon atoms according to R ³ include a linear, branched, or cyclic alkyl group or alkenyl group, an aromatic group, and a hydrocarbon group that combines these groups. Can be mentioned.

  Examples of the alcohol solvent represented by the general formula (2) include n-pentanol, cyclopentanol, n-hexanol, cyclohexanol, decanol, dodecanol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol.

  Among the compounds exemplified as the film forming aid (B), the glycol ether solvent represented by the general formula (1) is preferable. In particular, the glycol ether solvent represented by the general formula (1) is preferably ethylene glycol mono n-butyl ether, propylene glycol mono n-butyl ether, or dipropylene glycol mono n-propyl ether. These are effective as a film-forming aid in a small amount with respect to the water-dispersed base polymer, have a fast drying speed when the pressure-sensitive adhesive layer is formed, and have good durability of the pressure-sensitive adhesive layer formed. It is.

  Even when the plasticizer (C) is added to the water-dispersed pressure-sensitive adhesive, which is an aqueous dispersion containing the water-dispersed base polymer (A), the pressure-sensitive adhesive layer is not aggregated in the water-dispersed liquid. In the coating state at the time of formation, it has the effect of plasticizing the coating film. The plasticizer (C) is generally used as a plasticizer, and usually remains in the pressure-sensitive adhesive layer after the coating film is dried to form the pressure-sensitive adhesive layer.

  As such a plasticizer (C), for example, a compound having a boiling point of 230 to 420 ° C. can be used. The boiling point is preferably 240 to 400 ° C, more preferably 260 to 380 ° C. The boiling point is a measured value under normal pressure (1 atm).

  The plasticizer (C) is preferably a liquid that exhibits a liquid state at normal temperature (23 ° C.). What has melting | fusing point of a plasticizer (C) is 30 degrees C or less is preferable. The melting point is a measured value under normal pressure (1 atm).

  As the plasticizer (C), for example, an ester plasticizer obtained from a carboxylic acid compound and an alcohol compound is preferably used. The ester plasticizer is preferably a polyvalent carboxylic acid polyester obtained from a polyvalent carboxylic acid and a monohydric alcohol. Examples of the polyvalent carboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, isopropylmalonic acid, 2-methylglutaric acid, pimelic acid, 2,2-dimethylglutaric acid, suberic acid, azelaic acid, and sebacin. An aliphatic group having a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms such as acid, 1,2-cyclohexanedicarboxylic acid, 2,3-norbornanedicarboxylic acid, 2,3-norbornenedicarboxylic acid, etc. Or alicyclic polycarboxylic acid; phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, biphenyltetracarboxylic acid, 2,3-anthracene dicarboxylic acid, 9,10-dioxo-9,10-dihydro Aromatic polycarboxylic acids such as -2,3-anthracene dicarboxylic acid and anhydrides thereof can be mentioned. As said monohydric alcohol, the alkyl alcohol which has a C1-C18 linear, branched or cyclic alkyl group can be used. Examples of the monohydric alcohol include diethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, polypropylene glycol monomethyl ether, diethylene glycol monoethyl ether, polyethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, polypropylene glycol monoethyl. Examples thereof include polyalkylene glycol monoalkyl ethers such as ether, diethylene glycol monobutyl ether, polyethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and polypropylene glycol monobutyl ether. Specific examples of the ester plasticizer obtained from the polyvalent carboxylic acid and the monohydric alcohol include, for example, adipic acid dialkyl esters such as diethyl adipate and diisobutyl adipate; dimethyl sebacate, diethyl sebacate, diisopropyl sebacate And aliphatic divalent carboxylic acid dialkyl esters such as sebacic acid alkyl diesters such as di-n-butyl sebacate. In addition, dialkyl phthalates such as diethyl phthalate, di-n-butyl phthalate, di-n-octyl phthalate and n-butyl 2-ethylhexyl phthalate; aromatic polycarboxylic acid alkyl esters such as alkyl esters of trimellitic acid Etc.

  Among the above polyvalent carboxylic acid polyesters, aliphatic divalent carboxylic acid dialkyl esters are preferred, particularly adipic acid, because they are effective in a small amount and do not affect adhesive properties and are not environment-related regulated substances. Dialkyl esters and sebacic acid dialkyl esters are preferred.

  Moreover, as said ester plasticizer, the ester plasticizer obtained from monohydric carboxylic acid and a polyhydric alcohol is mentioned, for example. As the monovalent carboxylic acid, an alkyl carboxylic acid having a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms can be used. Examples of the polyhydric alcohol include polyhydric alcohols having a linear, branched or cyclic alkylene group having 1 to 18 carbon atoms. For example, mono- and dialkyls of 2,2,4-trimethyl-1,3-pentanediol obtained from fatty acids having 4 to 8 carbon atoms and 2,2,4-trimethyl-1,3-pentanediol (provided that alkyl Ester having a group having 4 to 8 carbon atoms can be preferably used. Examples of the alkyl group include linear, branched or cyclic alkyl groups having 4 to 8 carbon atoms. Specific examples include 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and the like. In particular, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate is preferable. Mono- and dialkyl esters of 2,2,4-trimethyl-1,3-pentanediol have a high plasticizing effect on the coating film in a small amount with respect to the water-dispersed base polymer. The drying speed is high, and the durability of the formed pressure-sensitive adhesive layer is good. Further, after the coating film is dried and the pressure-sensitive adhesive layer is formed, it is preferable that the coating film is evaporated and does not remain in the pressure-sensitive adhesive layer or there is little.

  The ester plasticizer includes a monovalent alkyl carboxylic acid having a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms and a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms. An ester plasticizer obtained from a monohydric alcohol having Examples thereof include ethyl stearate and 2-ethylhexyl palmitate. In addition, examples of the plasticizer (C) other than the ester plasticizer include phosphate esters such as triphenyl phosphate, tricresyl phosphate, biphenyl-diphenyl phosphate, and dimethyl ethyl phosphate.

  In the optical water-dispersed pressure-sensitive adhesive of the present invention, the ratio of the film-forming auxiliary (B) and / or the plasticizer (C) is such that the water-dispersed base polymer (A) and the film-forming auxiliary (B ) And / or 0.1 to 15 parts by weight with respect to 100 parts by weight of the optical water-dispersed pressure-sensitive adhesive comprising an aqueous dispersion containing the plasticizer (C). The ratio is preferably 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight. If the said ratio is less than 0.1 weight part, it will be difficult to acquire the sufficient effect by mix | blending a film-forming auxiliary | assistance (B) and / or a plasticizer (C). When the ratio exceeds 15 parts by weight, the ratio of the film forming aid (B) and / or the plasticizer (C) to the optical water-dispersed pressure-sensitive adhesive increases, and a large amount of these remain in the pressure-sensitive adhesive layer. On the contrary, the depolarization property is deteriorated.

  Moreover, when using the said film-forming auxiliary | assistance (B) independently, it is preferable that the said ratio is 0.1-15 weight part, Furthermore, it is preferable that it is 0.5-10 weight part. Moreover, when using the said plasticizer (C) independently, it is preferable that the said ratio is 0.1-10 weight part, Furthermore, it is preferable that it is 0.3-5 weight part. Moreover, when using together the said film-forming auxiliary | assistance (B) and the said plasticizer (C), the said ratio which concerns on these total amount is 0.1-15 weight part, Preferably 0.5-10 weight part In such a range, the total amount of the film forming aid (B) and the plasticizer (C) is adjusted within the above range.

  The water-dispersed pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the present invention includes, for example, an aqueous dispersion according to the water-dispersed base polymer (A), and the film-forming auxiliary (B) and the plasticizer (C ) Can be obtained as an aqueous dispersion.

  The water-dispersed pressure-sensitive adhesive of the present invention contains the above components, and the total solid content weight of these components is 80% by weight or more of the solid content weight of the water-dispersed liquid according to the water-dispersed pressure-sensitive adhesive, Furthermore, it is preferable to use it so that it may become 90 weight% or more, further 95 weight% or more, and also 100%. That is, in addition to the above components, other components can be used in the aqueous dispersion according to the water-dispersed pressure-sensitive adhesive. The proportion of other components is preferably 10% by weight or less from the viewpoint of suppressing the haze deterioration of the pressure-sensitive adhesive layer.

  Moreover, as said other component, a crosslinking agent can be contained as needed. As the crosslinking agent, generally used ones such as an isocyanate crosslinking agent, an epoxy crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a carbodiimide crosslinking agent, and a metal chelate crosslinking agent can be used. These cross-linking agents can be appropriately determined according to the base polymer, and have an effect of cross-linking by reacting with a functional group introduced into the base polymer.

  The blending ratio of the base polymer and the crosslinking agent is not particularly limited, but is usually blended at a ratio of about 10 parts by weight or less of the crosslinking agent (solid content) to 100 parts by weight of the base polymer (solid content). The blending ratio of the crosslinking agent is preferably 0.001 to 10 parts by weight, more preferably about 0.01 to 5 parts by weight.

  Furthermore, the water-dispersed pressure-sensitive adhesive of the present invention includes a viscosity modifier, a release modifier, a tackifier, a plasticizer, a softener, glass fiber, glass beads, metal powder, and other inorganic powders as necessary. Fillers, pigments, colorants (pigments, dyes, etc.), pH adjusters (acids or bases), antioxidants, ultraviolet absorbers, silane coupling agents, etc., and also within the scope of the present invention Various additives can be used as appropriate. Moreover, it is good also as an adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility. These additives can also be blended as an emulsion.

  The optical pressure-sensitive adhesive layer of the present invention is formed of the water-dispersed pressure-sensitive adhesive. The pressure-sensitive adhesive layer can be formed by applying the water-dispersed pressure-sensitive adhesive to a support substrate (optical film or release film) and then drying it.

  The pressure-sensitive adhesive optical film of the present invention is obtained by laminating the pressure-sensitive adhesive layer on one side or both sides of an optical film. The pressure-sensitive adhesive optical film of the present invention is formed by applying the water-dispersed pressure-sensitive adhesive to an optical film or a release film and drying it. When the pressure-sensitive adhesive layer is formed on the release film, the pressure-sensitive adhesive layer is attached to the optical film and transferred.

  Various methods are used for the application process of the water-dispersed pressure-sensitive adhesive. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

  Moreover, in the said application | coating process, the application quantity is controlled so that the adhesive layer formed may become predetermined | prescribed thickness (thickness after drying). The thickness (thickness after drying) of the pressure-sensitive adhesive layer is usually set in the range of about 1 to 100 μm, preferably 5 to 50 μm, and more preferably 10 to 40 μm.

  Next, in forming the pressure-sensitive adhesive layer, the applied water-dispersed pressure-sensitive adhesive is dried. The drying temperature is usually about 80 to 170 ° C, preferably 80 to 160 ° C, and the drying time is about 0.5 to 30 minutes, preferably 1 to 10 minutes.

  The drying temperature is preferably set at a temperature 80 ° C. or more higher than the glass transition temperature (Tg) of the pressure-sensitive adhesive layer. The glass transition temperature (Tg) of the pressure-sensitive adhesive layer is preferably −60 to −0 ° C., and more preferably −50 to −10 ° C. By setting the drying temperature at a temperature higher by 80 ° C. or more, the effect of the film forming aid (B) and / or the plasticizer (C) can be efficiently exhibited and exists between the interfaces of the polymer particles. The ratio of the components can be reduced, the refractive index change and the like are reduced, and light scattering is less likely to occur, thereby reducing the depolarization property. The drying temperature is more preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and even more preferably 150 ° C. or higher. If the drying temperature is too high, the release film is deformed by heat and it is difficult to obtain a pressure-sensitive adhesive layer with high film thickness uniformity. Therefore, the drying temperature is the glass transition temperature (Tg) of the pressure-sensitive adhesive layer. It is preferable to set in the range of 200 ° C. or less.

As described above, the optical pressure-sensitive adhesive layer of the present invention has a small depolarization value. For example, in the pressure-sensitive adhesive polarizing plate in which the optical pressure-sensitive adhesive layer is laminated on one surface of the polarizing plate, the difference ( P1−P2 ) between the polarization degree (P1) of the polarizing plate and the polarization degree (P2) of the pressure-sensitive adhesive polarizing plate is obtained. When the depolarization value is defined, the depolarization value can be controlled to a small value of 0.015 or less. The smaller the depolarization value, the more preferable, 0.012 or less is more preferable, and 0.010 or less is more preferable. For example, by satisfying the drying temperature, the depolarization value can be made 0.010 or less. In addition, the measurement of the polarization degree which concerns on a depolarization value is performed based on description of an Example, and the same depolarization value can be obtained irrespective of the kind of polarizing plate. The polarization degree of the polarizing plate used for the measurement of the depolarization value is preferably 99.000 or more, more preferably 99.000.
It is preferably 900 or more, more preferably 99.995 or more.

  Examples of the constituent material of the release film include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. However, a plastic film is preferably used from the viewpoint of excellent surface smoothness.

  The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The release film has a thickness of usually 5 to 200 μm, preferably about 5 to 100 μm. For the release film, if necessary, release and antifouling treatment with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, silica powder, etc., coating type, kneading type, An antistatic treatment such as a vapor deposition type can also be performed. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release film.

  When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a release film until practical use. In addition, said peeling film can be used as a separator of an adhesive optical film as it is, and can simplify in a process surface.

  In addition, in order to improve the adhesion between the pressure-sensitive adhesive layer on the surface of the optical film, an anchor layer is formed, or various pressure-sensitive adhesive treatments such as corona treatment and plasma treatment are performed, and then the pressure-sensitive adhesive layer is formed. can do. Moreover, you may perform an easily bonding process on the surface of an adhesive layer.

  As the material for forming the anchor layer, an anchor agent selected from polyurethane, polyester, polymers containing an amino group in the molecule and polymers containing an oxazolinyl group is preferably used, and an amino group in the molecule is particularly preferably used. And polymers containing an oxazolinyl group. Polymers containing an amino group in the molecule and polymers containing an oxazolinyl group are good because the amino group or oxazolinyl group in the molecule reacts with the carboxyl group in the adhesive or interacts with it such as ionic interactions. Secure adhesion.

  Examples of polymers containing an amino group in the molecule include polymers of amino group-containing monomers such as polyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, polyvinylpyrrolidine, dimethylaminoethyl acrylate, and the like.

  As the optical film used in the pressure-sensitive adhesive optical film of the present invention, those used for forming an image display device such as a liquid crystal display device are used, and the kind thereof is not particularly limited. For example, a polarizing plate is mentioned as an optical film. A polarizing plate having a transparent protective film on one or both sides of a polarizer is generally used.

  The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be prepared, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

  As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is bonded to one side of the polarizer by an adhesive layer. On the other side, as a transparent protective film, (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone A thermosetting resin such as a system or an ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  In addition, as an optical film, for example, it is used for forming a liquid crystal display device such as a reflection plate, an anti-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), a visual compensation film, and a brightness enhancement film. And an optical layer that may be formed. These can be used alone as an optical film, or can be laminated on the polarizing plate for practical use and used as one layer or two or more layers.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with the target phase difference characteristic.

  The pressure-sensitive adhesive optical film of the present invention can be preferably used for forming various image display devices such as liquid crystal display devices. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a display panel such as a liquid crystal cell, an adhesive optical film, and an illumination system as required, and incorporating a drive circuit. There is no particular limitation except that the pressure-sensitive adhesive optical film according to the present invention is used. As the liquid crystal cell, any type such as a TN type, STN type, π type, VA type, IPS type, or the like can be used.

  Appropriate liquid crystal display devices such as a liquid crystal display device in which an adhesive optical film is disposed on one side or both sides of a display panel such as a liquid crystal cell, and a lighting system using a backlight or a reflecting plate can be formed. In that case, the optical film by this invention can be installed in the one side or both sides of display panels, such as a liquid crystal cell. When optical films are provided on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight.

Example 1
(Preparation of monomer emulsion)
To the container, 780 parts of butyl acrylate, 20 parts of acrylic acid and 200 parts of methyl methacrylate were added and mixed to obtain a monomer component. Subsequently, to 200 parts of the monomer component prepared at the above ratio, 12 parts of Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.), which is a reactive surfactant, and 127 parts of ion-exchanged water are added. Using special machine chemical industry), the mixture was stirred at 6000 (rpm) for 5 minutes and forcedly emulsified to prepare a monomer emulsion (A-1).

  In a separate container, add 600 parts of the monomer component prepared in the above ratio to 12 parts of Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.), which is a reactive surfactant, and 382 parts of ion-exchanged water. Using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), the mixture was stirred and forcedly emulsified at 6000 (rpm) for 5 minutes to prepare a monomer emulsion (A-2).

(Preparation of emulsion type acrylic adhesive)
Next, 339 parts of the monomer emulsion (A-1) prepared above and 442 parts of ion-exchanged water were charged into a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer, a dropping funnel and a stirring blade, and then reacted. After the container was sufficiently purged with nitrogen, 0.6 part of ammonium persulfate was added and polymerized at 60 ° C. for 1 hour with stirring. Next, 994 parts of the monomer emulsion (A-2) were dropped over 3 hours while keeping the reaction vessel at 60 ° C., and then polymerized for 3 hours to obtain a polymer emulsion having a solid content concentration of 46.0%. Got.

  Next, after the polymer emulsion was cooled to room temperature, 10% ammonia water was added thereto to neutralize the pH to 8. Further, to 100 parts of the neutralized emulsion, 5.3 parts of ethylene glycol monobutyl ether (boiling point: 171 ° C., melting point: -70 ° C.) is added and mixed as a film forming aid, and the emulsion type has a solid content of 42.9%. An acrylic adhesive was obtained.

Example 2
In Example 1, in preparing the emulsion-type acrylic pressure-sensitive adhesive, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (boiling point 280 ° C. (Melting point -70 ° C.) (Each type acrylic pressure-sensitive adhesive having a solid content of 42.9% was obtained in the same manner as in Example 1 except that 5.3 parts of CS-12 manufactured by Chisso Corporation was used. .

Example 3
In Example 1, in preparing the emulsion type acrylic pressure-sensitive adhesive, 2 parts of di-n-butyl sebacate (boiling point: 349 ° C., melting point: −9 ° C.) was used as a plasticizer instead of the film forming aid. Obtained an emulsion type acrylic pressure-sensitive adhesive having a solid content of 44.3% in the same manner as in Example 1.

Example 4
In Example 1, in preparing the emulsion type acrylic pressure-sensitive adhesive, the solid content was changed in the same manner as in Example 1 except that the addition amount of ethylene glycol monobutyl ether, which is a film forming aid, was changed to 11.1 parts. A 40.6% emulsion-type acrylic pressure-sensitive adhesive was obtained.

Example 5
In Example 1, in the preparation of the emulsion-type acrylic pressure-sensitive adhesive, the amount of ethylene glycol monobutyl ether, which is a film forming aid, was changed to 11.2 parts, and di-n-butyl sebacate as a plasticizer. An emulsion type acrylic pressure-sensitive adhesive having a solid content of 40.2% was obtained in the same manner as in Example 1 except that 1 part was added.

Example 6
In Example 1, a monomer emulsion was prepared in the same manner as in Example 1 except that 780 parts of butyl acrylate, 20 parts of acrylic acid and 200 parts of styrene were used as monomer components. Moreover, the polymer emulsion was obtained like Example 1 except having used the said monomer emulsion. Then, after obtaining a neutralized emulsion in the same manner as in Example 1, 5.3 parts of ethylene glycol monobutyl ether as a film forming aid was added to and mixed with 100 parts of the neutralized emulsion to obtain a solid content of 42. A 7% emulsion-type acrylic pressure-sensitive adhesive was obtained.

Comparative Example 1
In Example 1, in the preparation of the emulsion type acrylic pressure-sensitive adhesive, an emulsion having a solid content of 45.2% was obtained in the same manner as in Example 1 except that ethylene glycol monobutyl ether as a film forming aid was not added. A type acrylic pressure-sensitive adhesive was obtained.

Comparative Example 2
In Example 1, in the preparation of the emulsion type acrylic pressure-sensitive adhesive, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Chisso Corp.) was used as a plasticizer instead of a film-forming aid. Emulsion type acrylic pressure-sensitive adhesive having a solid content of 33.9% was obtained in the same manner as in Example 1 except that 33.3 parts of CS-12) manufactured by the manufacturer were used.

Comparative Example 3
In Example 1, the preparation of the emulsion type acrylic pressure-sensitive adhesive was carried out in the same manner as in Example 1 except that 33.3 parts of di-n-butyl sebacate was used as the plasticizer instead of the film forming aid. An emulsion-type acrylic pressure-sensitive adhesive having a solid content of 33.9% was obtained.

<Formation of adhesive layer and creation of adhesive polarizing plate>
A release film (Mitsubishi Chemical Polyester Co., Ltd., Diafoil MRF-38, polyethylene terephthalate base material was prepared so that the thickness after drying of the emulsion type acrylic pressure-sensitive adhesive obtained in Examples and Comparative Examples was 20 μm. ) After coating with a die coater, it was dried at 120 ° C. for 5 minutes to form an adhesive layer. For the emulsion-type acrylic pressure-sensitive adhesive obtained in Example 1, a pressure-sensitive adhesive layer was formed in the same manner as above except that the drying temperature was changed to 150 ° C. The pressure-sensitive adhesive layer was bonded to two types of polarizing plates to prepare two types of pressure-sensitive polarizing plates. Two types of polarizing plates were prepared by the following method for polarizing plate (1). The polarization degree of the polarizing plate (1) is 99.99960. As the polarizing plate (2), a product name TEG-DU (polarization degree: 99.9633) manufactured by Nitto Denko Corporation was used.

<Production of Polarizing Plate (1)>
A 80 μm-thick polyvinyl alcohol film was stretched up to 3 times between rolls having different speed ratios while being dyed in an iodine solution of 0.3% concentration at 30 ° C. for 1 minute. Thereafter, the total draw ratio was stretched to 6 times while being immersed in an aqueous solution containing 60% at 4% concentration of boric acid and 10% concentration of potassium iodide for 0.5 minutes. Next, after washing by immersing in an aqueous solution containing potassium iodide at 30 ° C. and 1.5% concentration for 10 seconds, drying was performed at 50 ° C. for 4 minutes to obtain a polarizer. On one side of this polarizer, a saponified 80 μm thick triacetyl cellulose film was bonded with a polyvinyl alcohol adhesive. On the other surface of the polarizer, a 70 μm-thick cyclic olefin resin film (trade name “ZEONOR” manufactured by Nippon Zeon Co., Ltd.) is bonded with a polyvinyl alcohol adhesive to obtain a polarizing plate (1). It was.

  The following physical properties of the pressure-sensitive adhesive layer obtained above were measured, and the following evaluations were performed on the pressure-sensitive adhesive layers and pressure-sensitive polarizing plates obtained in Examples and Comparative Examples. The results are shown in Table 1.

  Table 1 shows the ratio of each monomer component in each example, the composition ratio (weight ratio), the additive ratio, the drying temperature, and the glass transition temperature of the pressure-sensitive adhesive layer. The ratio (parts) of the additive (film forming aid (B) and / or plasticizer (C)) is an approximate conversion value with respect to 100 parts by weight of the finally prepared emulsion type acrylic pressure-sensitive adhesive.

<Measuring method of glass transition temperature>
The glass transition temperature (Tg) of the pressure-sensitive adhesive layer was measured using a differential scanning calorimeter (device name: DSC220, manufactured by Seiko Instruments Inc.). Measurement conditions were such that 5 mg of the pressure-sensitive adhesive layer was placed in an aluminum pan, temperature conditions: −120 ° C. to 150 ° C., temperature increase: 20 ° C./min.

<Depolarization value>
The polarization degree of the polarizing plate and the adhesive polarizing plate was measured using a spectrophotometer with an integrating sphere (V7100 manufactured by JASCO Corporation). The degree of polarization is the minimum transmittance (K2) measured by setting the transmission axis of the polarizing plate or the adhesive polarizing plate in a direction perpendicular to the plane of vibration of the polarized light from the prism, and the polarizing plate or the adhesive polarizing plate. Is obtained by applying the maximum transmittance (K1) measured by rotating 90 degrees to the following equation.
Polarization degree (%) = {(K2−K1) / (K2 + K1)} × 100
Each transmittance is 100% of the completely polarized light obtained through the Grandteller prism polarizer.
This is indicated by a Y value obtained by correcting the visibility with a two-degree field of view (C light source) of JIS Z8701. The difference ( P1-P2 ) was calculated from the measurement results of the polarization degree (P1) of the polarizing plate measured above and the polarization degree (P2) of the pressure-sensitive adhesive polarizing plate, and a depolarization value was derived.

  The following liquid crystal display devices A and B were prepared using the adhesive polarizing plates obtained in the examples and comparative examples.

≪Liquid crystal display device A≫
A liquid crystal panel is taken out from a commercially available liquid crystal display device including a VA mode liquid crystal cell (manufactured by Sony Corporation, 46-inch liquid crystal television, trade name “BraviaKDL-46WS”), and polarizing plates disposed above and below the liquid crystal cell. All of the optical film was removed. A liquid crystal cell A was prepared by cleaning the front and back surfaces of the glass plate of the liquid crystal cell. On the viewing side of the liquid crystal cell A, the adhesive type polarizing plate obtained in the examples and comparative examples is adhesive type so that the absorption axis direction of the polarizing plate is substantially parallel to the long side direction of the liquid crystal cell A. The pressure-sensitive adhesive layer side of the polarizing plate was bonded to the liquid crystal cell A. Next, on the opposite side (backlight side) to the viewing side of the liquid crystal cell A, the pressure-sensitive adhesive polarizing plate obtained in the same Example and Comparative Example was used, and the absorption axis direction of the polarizing plate was longer than that of the liquid crystal cell A. The pressure-sensitive adhesive layer side of the pressure-sensitive adhesive polarizing plate was bonded to the liquid crystal cell A so as to be substantially orthogonal to the side direction. This is referred to as a liquid crystal panel A. The absorption axis directions of the polarizing plates on the viewing side of the liquid crystal panel A and the polarizing plate on the backlight side are substantially orthogonal. Liquid crystal panel A was combined with the backlight unit of the original liquid crystal display device to produce liquid crystal display device A.

≪Liquid crystal display device B≫
Liquid crystal display device B in the same manner as liquid crystal display device A, except that a commercially available liquid crystal display device including a TN mode liquid crystal cell (Toshiba Corporation, 10-inch notebook personal computer, product name “dynabookSS”) was used. Was made.

<Contrast measurement method>
For the liquid crystal display devices A and B, the contrast ratios (1) and (2) in the front direction were measured. The contrast ratio was measured after 30 minutes had passed since the backlight was turned on in a dark room at 23 ° C., and the lens was placed at the 50 cm position of the panel information using the product name “BM-5” manufactured by Topcon Corporation. The Y value of the XYZ display system when displaying a white image and a black image was measured. The contrast ratio “YW / YB” in the front direction was calculated from the Y value (YW: white luminance) in the white image and the Y value (YB: black luminance) in the black image. The contrast (1) of the liquid crystal display device A is preferably 2600 or more, preferably 2700 or more, 2800 or more, 2900 or more, and more preferably 300 or more. The contrast (2) of the liquid crystal display device B is preferably 500 or more, preferably 540 or more, 560 or more, and more preferably 600 or more.

In the table, BA: butyl acrylate (228.15K), AA: acrylic acid (379K.15), MMA: methyl methacrylate (378.15K), St: styrene (373.15K) are shown. The temperature in parentheses is the glass transition temperature (K) of the homopolymer of each monomer used for calculating the glass transition temperature.
* 1: Ethylene glycol monobutyl ether,
* 2: 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate,
* 3: Di-n-butyl sebacate.

Claims (11)

An optical water-dispersed pressure-sensitive adhesive comprising a water-dispersed base polymer (A) and a water-dispersed liquid containing a film-forming auxiliary (B) and / or a plasticizer (C),
The water-dispersed base polymer (A) is an acrylic polymer,
The film forming aid (B)
Formula ^{_{(1): R 1 - (}} CO) m - (OA) n -OR 2
(Wherein R ¹ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R ² is a hydrocarbon group having 1 to 10 carbon atoms, A is an alkylene group having 2 or 3 carbon atoms, n is an integer of 1 to 60, and m = 0 or 1. However, R ¹ is a hydrogen atom and m = 1 is excluded.)
The plasticizer (C) is an ester plasticizer obtained from a carboxylic acid compound and an alcohol compound, and has a boiling point of 230 to 420 ° C.
Optical water characterized in that the ratio of the film forming aid (B) and / or the plasticizer (C) is 0.1 to 15 parts by weight with respect to 100 parts by weight of the optical water-dispersed pressure-sensitive adhesive. Distributed adhesive.   The optically water-dispersed pressure-sensitive adhesive according to claim 1, wherein the film-forming auxiliary (B) is a high-boiling solvent having a boiling point of less than 110 to 230 ° C. The optical water-dispersed pressure-sensitive adhesive according to claim 1 or 2, wherein the ester plasticizer is a polyvalent carboxylic acid polyester obtained from a polyvalent carboxylic acid and a monohydric alcohol. The ester-based plasticizer, 2,2,4-trimethyl-1,3-pentanediol mono- and di (provided that 4 to 8 carbon atoms an alkyl group) according to claim 3, characterized in that the ester The water-dispersible pressure-sensitive adhesive for optical use described. The acrylic polymer as the water-dispersed base polymer (A) is composed of 60 to 99.9% by weight of a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 3 to 14 carbon atoms and a carboxyl group. 2. An acrylic polymer obtained by emulsion polymerization of a monomer component containing 0.1 to 10% by weight of a group-containing monomer in the presence of a radical polymerization initiator and a surfactant. 5. The optically water-dispersed pressure-sensitive adhesive according to any one of 4 above. The monomer component contains a copolymerization monomer in a proportion of 39% by weight or less, and the copolymerization monomer contains a high Tg monomer that makes the glass transition temperature (Tg) of the homopolymer 50 ° C. or more. The optically water-dispersed pressure-sensitive adhesive according to claim 5 . The optically water-dispersed pressure-sensitive adhesive according to claim 6 , wherein the high Tg monomer is a methacrylic acid alkyl ester having an alkyl group having 1 or 2 carbon atoms and / or a styrene monomer. An optical pressure-sensitive adhesive layer, which is formed by applying the optically water-dispersed pressure-sensitive adhesive according to any one of claims 1 to 7 , followed by drying. The pressure-sensitive adhesive optical film, wherein the optical pressure-sensitive adhesive layer according to claim 8 is laminated on at least one side of the optical film. The pressure-sensitive adhesive optical film is a pressure-sensitive adhesive polarizing plate in which the optical pressure-sensitive adhesive layer is laminated on one surface of a polarizing plate provided with a transparent protective film on at least one surface of a polarizer,
The depolarization value represented by the difference (P1-P2) between the degree of polarization (P1) of the polarizing plate and the degree of polarization (P2) of the adhesive polarizing plate satisfies 0.015 or less. Item 10. The pressure-sensitive adhesive optical film according to Item 9 . An image display device comprising at least one adhesive optical film according to claim 9 or 10 .