JP5552364B2 - Water-dispersed pressure-sensitive adhesive composition for optical film, pressure-sensitive adhesive layer for optical film, pressure-sensitive optical film, and image display device - Google Patents

Description

  The present invention relates to a water-dispersed pressure-sensitive adhesive composition for optical films and an optical film pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. Moreover, this invention relates to the adhesive optical film with which the said adhesive layer is provided in the 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 phase difference plate, an optical compensation film, a brightness enhancement film, and a film in which these are laminated can be used.

  In a liquid crystal display device or the like, it is indispensable to dispose polarizing elements on both sides of a liquid crystal cell because of its image forming method, and generally a polarizing plate is attached. 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, since the adhesive has the merit that a drying step is not required for fixing the optical film, the adhesive is an adhesive optical film provided in advance as an adhesive layer on one side of the optical film. Generally used.

  Since the optical film used for the adhesive optical film is likely to shrink and expand under heating and humidification conditions, the adhesive optical film is likely to be lifted or peeled after being bonded to the liquid crystal cell. Therefore, the pressure-sensitive adhesive layer is required to have durability against heating and humidification. Conventionally, as a 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.

  In recent years, solventless pressure-sensitive adhesives that do not use organic solvents have been actively developed from the viewpoints of reducing the burden on the global environment and improving work stability. As a solventless adhesive, for example, a water-dispersed adhesive in which an adhesive polymer component is dispersed in water using water as a dispersion medium is known. However, since the water-dispersed pressure-sensitive adhesive generally contains a surfactant such as an emulsifier and a dispersant as a water-soluble dispersion stabilizing component, the pressure-sensitive adhesive layer formed of the water-dispersed pressure-sensitive adhesive is affected by the water-soluble component. Therefore, foaming is likely to occur under heating conditions, and peeling or the like is likely to occur under humidified conditions, causing a problem in durability.

  In order to improve this durability, some proposals have been made in the field of optical films. For example, as a water-dispersed pressure-sensitive adhesive for optical films that can improve the adhesion of a liquid crystal panel to a glass substrate, it is proposed to use an acrylic polymer emulsion using a silane monomer together with a (meth) acrylic acid alkyl ester. (Patent Document 1). In addition, as a water-dispersed adhesive for optical films that can improve the adhesion to the glass substrate of the liquid crystal panel under humidified conditions, an acrylic polymer using a phosphate group-containing monomer together with a (meth) acrylic acid alkyl ester It has been proposed to use an emulsion (Patent Document 2).

  On the other hand, as a water-dispersed pressure-sensitive adhesive other than for optical films, for example, as a water-dispersed pressure-sensitive adhesive with improved adhesion to nonpolar substrates such as polyolefin, the glass transition temperature (Tg) is 90 to 105 ° C. An aqueous dispersion (A) of a high Tg copolymer and an aqueous dispersion (B) of a low Tg copolymer having a Tg of −75 to −45 ° C., (A) / (B) = 1/99 What is contained at a ratio of ˜15 / 85 (solid content weight ratio) has been proposed (Patent Document 3). In addition, as an emulsion-type pressure-sensitive adhesive composition exhibiting high adhesive strength to both hard-to-adhere adherends such as polyolefin and rough-surface adherends such as corrugated cardboard, Tg is less than −40 ° C. 65 to 80 parts by mass of Tg polymer emulsion (A), 20 to 35 parts by mass of high Tg polymer emulsion (B) having a Tg of −40 ° C. to 0 ° C., and an aqueous solution having two or more oxazoline groups in one molecule A cross-linking agent (C-1) and / or a cross-linking agent (C-2) having two or more aziridinyl groups in one molecule and a tackifier resin (D) have been proposed (Patent Literature) 4).

JP 2002-309212 A JP 2007-186661 A JP 2006-016517 A JP 2006-124691 A

  The water-dispersed pressure-sensitive adhesives of Patent Documents 1 and 2 are satisfactory with respect to durability after a certain humidification test. However, the water-dispersed pressure-sensitive adhesives in Patent Documents 1 and 2 are peeled off when the pressure-sensitive adhesive optical film is taken out from a high-temperature humidified environment at room temperature and then stored for a long time (hereinafter, this peel-off is referred to as time-lapse). It has been newly found that it is not enough to suppress the effect.

  Further, in the water-dispersed pressure-sensitive adhesives of Patent Documents 3 and 4, a non-polar base material such as polyolefin is an adherend, and therefore a tackifier is used for the water-dispersed pressure-sensitive adhesive. The pressure-sensitive adhesive layer formed by the type pressure-sensitive adhesive had high haze, and could not be applied for optical films. In particular, the water-dispersed pressure-sensitive adhesives of Patent Documents 3 and 4 do not have sufficient humidification durability when the adherend is a polar glass substrate, and do not satisfy the above-described peeling over time.

  The present invention is a water-dispersed pressure-sensitive adhesive applied to an optical film, and the pressure-sensitive adhesive layer formed by the water-dispersed pressure-sensitive adhesive is taken out at room temperature from peeling in a humidified environment and a high-temperature humidified environment. It is an object to provide a water-dispersed pressure-sensitive adhesive composition for an optical film, which can suppress peeling over time that occurs when stored for a long time. Moreover, an object of this invention is to provide the adhesive layer for optical films formed with the said water-dispersed adhesive composition for optical films.

  Another object of the present invention is to provide an adhesive optical film in which the optical film adhesive layer is laminated on at least one side of the optical film. Furthermore, an 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-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by the following water-dispersed pressure-sensitive adhesive composition for optical films, and have completed the present invention.

That is, the present invention contains (meth) acrylic acid alkyl ester as a monomer unit, and has a glass transition temperature (however, the glass transition temperature is calculated based on the monofunctional monomer in the monomer unit) of −55 ° C. or higher. An aqueous dispersion of a (meth) acrylic copolymer (A) at 0 ° C. or lower;
(Meth) acrylic acid alkyl ester is contained as a monomer unit, and the glass transition temperature (where the glass transition temperature is calculated based on the monofunctional monomer in the monomer unit) is from 0 ° C. to 180 ° C. (meta ) Containing an aqueous dispersion of the acrylic copolymer (B), and
At least one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) contains a carboxyl group-containing monomer as a monomer unit,
The difference between the glass transition temperature of the (meth) acrylic copolymer (A) and the glass transition temperature of the (meth) acrylic copolymer (B) is 50 ° C. or more, and
The mixing ratio of the aqueous dispersion of the (meth) acrylic copolymer (A) and the aqueous dispersion of the (meth) acrylic copolymer (B) is (A) / (B) = 50 to 90 / It is related with the water dispersion type adhesive composition for optical films characterized by containing in the range of 10-50 (solid content weight ratio).

  In the water-dispersed pressure-sensitive adhesive composition for optical films, at least one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) is an alkoxysilyl group as a monomer unit. Containing monomer (however, the alkoxysilyl group-containing monomer is excluded from the monofunctional monomer related to the calculation of the glass transition temperature), and the proportion of the alkoxysilyl group-containing monomer is a (meth) acrylic copolymer. It is preferable that it is 0.001-1 weight% of the total monomer unit of a polymer (A) or a (meth) acrylic-type copolymer (B).

  In the water-dispersed pressure-sensitive adhesive composition for optical films, at least one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) is a phosphate group as a monomer unit. It is preferable to contain a containing monomer. The proportion of the phosphate group-containing monomer is preferably 0.1 to 20% by weight of the total monomer units of the (meth) acrylic copolymer (A) or (meth) acrylic copolymer (B). .

  In the water-dispersed pressure-sensitive adhesive composition for optical films, an aqueous dispersion of the (meth) acrylic copolymer (A) and an aqueous dispersion of the (meth) acrylic copolymer (B) are obtained by emulsion polymerization. It is preferable that the polymer emulsion is obtained.

  Moreover, this invention relates to the adhesive layer for optical films formed by apply | coating the said water dispersion type adhesive composition for optical films, and drying.

  The pressure-sensitive adhesive layer preferably has a haze value (H20) of 0 to 1% when the pressure-sensitive adhesive layer has a thickness of 20 μm.

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

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

  The humidification durability related to the adhesive optical film is recognized as peeling caused by storage in a humidified environment (for example, 60 ° C., 90% RH). In short, the peeling is caused by the adhesive type optical film being placed in a humidified environment, so that the adhesive force of the adhesive layer to the adherend becomes insufficient, and the adhesive layer and the adherend (for example, glass) Is generated at the interface with (hereinafter referred to as humidified peel).

  On the other hand, it is newly found that there is a problem related to peeling (temporal peeling) even when the adhesive optical film is taken out from a high temperature humidified environment (for example, 85 ° C., 85% RH) at room temperature and stored for a long time. It was. However, it has been found that time-dependent peeling occurs in a different mechanism from humidified peeling. In other words, the time-lapse peel-off was caused by the optical film expanded in a high-temperature humidified environment, and the pressure-sensitive adhesive layer that expanded following the expansion, taken out from the high-temperature humidified environment at room temperature and stored for a long time (about 100 hours or more). In this case, as a result of the optical film shrinking more than the state before expansion, the end of the optical film warps in the direction opposite to the glass surface (shrinking direction), and the optical film shrinks and warps. It was found that a tensile stress acts on the adhesive layer and the adherend, and the pressure-sensitive adhesive layer that cannot withstand the tensile stress is generated by cohesive failure. In other words, the present inventors have found that the problem related to peeling over time that occurs when taking out from a high-temperature humidified environment at room temperature and storing it for a long time is not due to insufficient adhesion of the adhesive, but due to insufficient cohesive strength of the adhesive layer. The present invention has been found out and the present invention has been completed from this new knowledge.

  That is, in the present invention, in order to impart cohesive force to the pressure-sensitive adhesive layer, as a water-dispersed pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer, a normal (meth) acrylic copolymer having a low glass transition temperature is used. In addition to the aqueous dispersion of (A), an aqueous dispersion of (meth) acrylic copolymer (B) having a predetermined high glass transition temperature is used at a predetermined ratio. The pressure-sensitive adhesive layer formed by the water-dispersed pressure-sensitive adhesive composition of the present invention has an excellent cohesive force while maintaining the adhesive force to the adherend, and suppresses the above-mentioned humid peeling and temporal peeling. Can do.

  As described above, an aqueous dispersion of a (meth) acrylic copolymer (A) having a low glass transition temperature and a (meth) acrylic copolymer having a high glass transition temperature as a water-dispersed pressure-sensitive adhesive composition. By mixing and using the aqueous dispersion of the blend (B), the (meth) acrylic copolymer (A) having a low glass transition temperature ensures the adhesive force of the pressure-sensitive adhesive layer and prevents humidification peeling. The cohesive force of the pressure-sensitive adhesive layer can be increased by the (meth) acrylic copolymer (B) having a high glass transition temperature, and peeling with time can be prevented.

  In addition, the aqueous dispersion of the (meth) acrylic copolymer (B) having a high glass transition temperature is effective in preventing peeling over time, and when the adhesive optical film is stored in a humidified environment. The expansion of the optical film in the initial stage can be suppressed, which is also preferable for suppressing humidification peeling.

  The water-dispersed pressure-sensitive adhesive composition of the present invention includes an aqueous dispersion of a (meth) acrylic copolymer (A) having a low glass transition temperature and a (meth) acrylic copolymer having a high glass transition temperature. The mixture (B) is used by mixing with an aqueous dispersion, and the aqueous dispersions of these (meth) acrylic copolymers (A) and (B) are independent of each other and exhibit characteristics. Therefore, it is considered that humidification peeling and aging peeling related to humidification durability can be suppressed. Therefore, the monomer that forms the (meth) acrylic copolymers (A) and (B), instead of using the (meth) acrylic copolymers (A) and (B) in a mixed manner as in the present invention. When an aqueous dispersion of an acrylic polymer obtained by mixing and uniformly polymerizing is used alone, the effects of the present invention cannot be obtained.

  The water-dispersed pressure-sensitive adhesive composition for an optical film of the present invention has an aqueous dispersion of a (meth) acrylic copolymer (A) having a glass transition temperature of −55 ° C. or higher and 0 ° C. or lower, and a glass transition temperature of 0 ° C. or higher. And an aqueous dispersion of a (meth) acrylic copolymer (B) at 180 ° C. or lower.

  As described above, the glass transition temperature of the (meth) acrylic copolymer (A) is −55 ° C. or more and 0 ° C. or less. In this range, the cohesive force is reduced while ensuring the adhesiveness of the pressure-sensitive adhesive. Can be suppressed. The glass transition temperature is preferably −20 ° C. or lower, more preferably −30 ° C. or lower, further −35 ° C. or lower, and further preferably −40 ° C. or lower. When the glass transition temperature of the (meth) acrylic copolymer (A) exceeds 0 ° C., the adhesiveness as a pressure-sensitive adhesive is lowered and humid peeling is likely to occur. On the other hand, the glass transition temperature is preferably −50 ° C. or higher, more preferably −45 ° C. or higher (preferably higher than −45 ° C.). When the glass transition temperature of the (meth) acrylic copolymer (A) is less than −55 ° C., the cohesive force of the pressure-sensitive adhesive is reduced, and peeling with time tends to occur.

  As described above, the glass transition temperature of the (meth) acrylic copolymer (B) is 0 ° C. or higher and 180 ° C. or lower. In this range, the decrease in cohesive force is suppressed while ensuring the adhesiveness of the pressure-sensitive adhesive. be able to. The glass transition temperature is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, further 70 ° C. or higher, further 80 ° C. or higher, and more preferably 85 ° C. or higher. When the glass transition temperature of the (meth) acrylic copolymer (B) is less than 50 ° C., the cohesive force of the pressure-sensitive adhesive is lowered, and peeling with time tends to occur. On the other hand, the glass transition temperature is preferably 110 ° C. or less, more preferably 100 ° C. or less, and further preferably 90 ° C. or less (preferably less than 90 ° C.) from the viewpoint of suppressing humidification peeling.

  The difference between the glass transition temperature of the (meth) acrylic copolymer (A) and the glass transition temperature of the (meth) acrylic copolymer (B) is 50 ° C. or more. The difference in the glass transition temperature is 70 ° C. or more, further 80 ° C. or more, further 90 ° C. or more, further 100 ° C. or more, further 110 ° C. or more, and further 120 ° C. or more. This is preferable from the viewpoint of suppressing a decrease in cohesive force while ensuring adhesiveness.

The glass transition temperature of the (meth) acrylic copolymer (A) and the glass transition temperature of the (meth) acrylic copolymer (B) are determined from the monomer units constituting each polymer and their proportions, based on the FOX. It is a theoretical value calculated by the formula:
Formula of FOX: 1 / Tg = w ₁ / Tg ₁ + w ₂ / Tg ₂ +... + W _n / Tg _n
(Tg: Glass transition temperature (K) of polymer, Tg ₁ , Tg ₂ ,... Tg _n : Glass transition temperature (K) of homopolymer of each monomer, w ₁ , w ₂ ,... W _n : (Weight fraction of each monomer)
However, the glass transition temperature of the (meth) acrylic polymer (A) and the glass transition temperature of the (meth) acrylic copolymer (B) are calculated based on the monofunctional monomer. That is, even in the case where each polymer contains a polyfunctional monomer as a constituent monomer unit, the amount of the polyfunctional monomer used is small, and the glass transition temperature of the copolymer is small. Not included in temperature calculation. Moreover, since it is recognized as a polyfunctional monomer for the alkoxysilyl group-containing monomer, it is not included in the calculation of the glass transition temperature. The theoretical glass transition temperature obtained from the FOX equation is in good agreement with the measured glass transition temperature obtained by DSC, dynamic viscoelasticity, and the like.

  The (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) contain (meth) acrylic acid alkyl ester as a monomer unit and satisfy the glass transition temperature. For example, the type of monomer unit and the component composition are not particularly limited. 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.

  The (meth) acrylic acid alkyl ester used in the (meth) acrylic polymer (A) preferably has a water solubility in a certain range from the viewpoint of emulsion polymerization reactivity, and controls the glass transition temperature. It is preferable that the main component is an alkyl acrylate ester having 1 to 18 carbon atoms in the alkyl group. Specific examples of the alkyl acrylate ester include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, Examples include acrylic acid alkyl esters such as n-octyl acrylate, lauryl acrylate, tridecyl acrylate, and stearyl acrylate. These can be used alone or in combination of two or more. Of these, alkyl acrylates having 3 to 9 carbon atoms in the alkyl group such as propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate are preferable. The alkyl acrylate is preferably contained in an amount of 60 to 99.9% by weight of the total monomer units, more preferably 70 to 99.9% by weight, further 80 to 99.9% by weight, and further 80 to 99% by weight. Further, it is preferably 80 to 95% by weight.

  In addition, the (meth) acrylic copolymer (A) preferably has a water solubility within a certain range from the viewpoint of emulsion polymerization reactivity, and since the glass transition temperature is easily controlled, A methacrylic acid alkyl ester having 1 to 18 carbon atoms can be used. Specific examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate. And alkyl methacrylates such as n-octyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, and isobornyl methacrylate. These can be used alone or in combination of two or more. Among these, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate and the like are preferable. The methacrylic acid alkyl ester is preferably 39.9% by weight or less of the total monomer units, more preferably 30% by weight or less, further 20% by weight or less, further 15% by weight or less, and further 10% by weight or less. Is preferred.

  On the other hand, the (meth) acrylic acid alkyl ester used for the (meth) acrylic copolymer (B) preferably has a water solubility in a certain range from the viewpoint of emulsion polymerization reactivity, and controls the glass transition temperature. Therefore, it is preferable that the alkyl group having 1 to 18 carbon atoms in the above alkyl group is a main component. The alkyl methacrylate can be used alone or in combination of two or more. Specific examples of the methacrylic acid alkyl ester include those similar to the above. Among the examples, methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, isobornyl methacrylate and the like are preferable. The alkyl methacrylate is preferably contained in an amount of 60 to 99.9% by weight of the total monomer units, more preferably 70 to 99.9% by weight, further 80 to 99.9% by weight, and further 80 to 99% by weight. Further, it is preferably 80 to 95% by weight.

  In addition, the (meth) acrylic copolymer (B) preferably has a water solubility within a certain range from the viewpoint of emulsion polymerization reactivity, and the glass transition temperature is easily controlled. Acrylic acid alkyl ester having 1 to 18 carbon atoms can be used. The alkyl acrylate ester can be used alone or in combination of two or more. Specific examples of the acrylic acid alkyl ester include those similar to the above. Among these examples, alkyl acrylates having 3 to 9 carbon atoms in the alkyl group such as propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate are preferable. The acrylic acid alkyl ester is preferably 39.9% by weight or less of the total monomer units, more preferably 5 to 30% by weight, and further preferably 5 to 20% by weight.

  In addition, at least one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) is a carboxyl group for improving the adhesive property of the pressure-sensitive adhesive and imparting stability to the emulsion. Group-containing monomers are used. 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, a vinyl group, such as (meth) acrylic acid, itaconic acid, maleic acid, Examples include fumaric acid, crotonic acid, carboxyethyl acrylate, and carboxypentyl acrylate. The carboxyl group-containing monomer may be contained as a monomer unit in either the (meth) acrylic copolymer (A) or the (meth) acrylic copolymer (B), and is contained only in one. However, it is preferably contained in both. The carboxyl group-containing monomer is preferably contained in an amount of 0.1 to 10% by weight of the total monomer units of the (meth) acrylic copolymer (A) or (meth) acrylic copolymer (B), and more preferably 0. It is preferably 5 to 7% by weight, more preferably 1 to 5% by weight.

  In the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B), in addition to the (meth) acrylic acid alkyl ester and the carboxyl group-containing monomer, stabilization of an aqueous dispersion, It is related to unsaturated double bonds such as (meth) acryloyl group or vinyl group for the purpose of improving the adhesiveness of the adhesive layer to the substrate such as an optical film and further improving the initial adhesiveness to the adherend. One or more copolymerization monomers having a polymerizable functional group can be introduced by copolymerization.

  Examples of the copolymerization monomer include alkoxysilyl group-containing monomers. The alkoxysilyl group-containing monomer is a silane coupling agent-based unsaturated monomer having at least one unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having an alkoxysilyl group. The alkoxysilyl group-containing monomer is preferable for imparting a crosslinked structure to the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) and improving the adhesion to glass.

  Examples of the alkoxysilyl group-containing monomer include alkoxysilyl group-containing (meth) acrylate monomers and alkoxysilyl group-containing vinyl monomers. Examples of the alkoxysilyl group-containing (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 , (Meth) acryloyloxyalkyl-trialkoxysilane such as 3- (meth) acryloyloxypropyl-triisopropoxysilane, 3- (meth) acryloyloxypropyl-tributoxysilane; , (Meth) 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 -Methyldiisopropoxysilane, 3- (meth) acryloyloxypropyl-methyldibutoxysilane, 3- (meth) acryloyloxypropyl-ethyldimethoxysilane, 3- (meth) acryloyloxy Propyl-ethyldiethoxysilane, 3- (meth) acryloyloxypropyl-ethyldipropoxysilane, 3- (meth) acryloyloxypropyl-ethyldiisopropoxysilane, 3- (meth) acryloyloxypropyl-ethyldibutoxysilane, (Meth) acryloyloxyalkyl-alkyldialkoxysilanes such as 3- (meth) acryloyloxypropyl-propyldimethoxysilane and 3- (meth) acryloyloxypropyl-propyldiethoxysilane, and (meth) acryloyloxy corresponding thereto Alkyl-dialkyl (mono) alkoxysilane and the like can be mentioned. In addition, as an alkoxysilyl group-containing vinyl monomer, for example, vinyltrialkoxysilane such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, etc. Vinylalkyldialkoxysilanes and vinyldialkylalkoxysilanes such as vinylmethyltrimethoxysilane, vinylmethyltriethoxysilane, β-vinylethyltrimethoxysilane, β-vinylethyltriethoxysilane, γ-vinylpropyltrimethoxysilane , Γ-vinylpropyltriethoxysilane, γ-vinylpropyltripropoxysilane, γ-vinylpropyltriisopropoxysilane, γ-vinylpropyltributoxysilane, etc. Other alkyltrialkoxysilane, these correspond and (vinyl) alkyl dialkoxy silanes, and the like (vinyl alkyl) dialkyl (mono) alkoxysilanes.

  The alkoxysilyl group-containing monomer may be contained in either the (meth) acrylic copolymer (A) or the (meth) acrylic copolymer (B), and is contained only in one. Also good. The proportion of the alkoxysilyl group-containing monomer is preferably 0.001 to 1% by weight of the total monomer units of the (meth) acrylic copolymer (A) or (meth) acrylic copolymer (B), Furthermore, it is preferably 0.01 to 0.5% by weight, more preferably 0.03 to 0.1% by weight. If it is less than 0.001% by weight, the effect of using an alkoxysilyl group-containing monomer (addition of a crosslinked structure, adhesion to glass) cannot be sufficiently obtained. On the other hand, if it exceeds 1% by weight, the pressure-sensitive adhesive layer is crosslinked. The degree becomes too high, and the pressure-sensitive adhesive layer may be cracked over time.

  Moreover, a phosphoric acid group containing monomer is mentioned as a copolymerization monomer. The phosphate group-containing monomer has an effect of improving the adhesion to glass.

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 (2), 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.

  The phosphate group-containing monomer may be contained in any one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B), and is contained only in one. Also good. The proportion of the phosphate group-containing monomer is preferably 0.1 to 20% by weight of the total monomer units of the (meth) acrylic copolymer (A) or (meth) acrylic copolymer (B). If it is less than 0.1% by weight, the effect of using a phosphate group-containing monomer (suppression of the generation of linear bubbles) cannot be sufficiently obtained.

  Specific examples of the copolymerizable monomer other than the alkoxysilyl group-containing monomer and the phosphate group-containing monomer include, for example, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; for example, phenyl (meth) acrylate (Meth) acrylic acid aryl esters, for example, vinyl esters such as vinyl acetate and vinyl propionate; for example, styrenic monomers such as styrene; for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, etc. Epoxy group-containing monomers; for example, hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; for example, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl ( (Meth) acrylamide, N- Sopropyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, (meth) acryloylmorpholine, aminoethyl (meth) acrylate, (meth) acrylic acid Nitrogen atom-containing monomers such as N, N-dimethylaminoethyl and t-butylaminoethyl (meth) acrylate; 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; and olefins such as ethylene, propylene, isoprene, butadiene and isobutylene Monomers, for example, vinyl ether monomers such as vinyl ether; halogen atom-containing monomers such as vinyl chloride; and others such as N-vinyl pyrrolidone, N- (1-methylvinyl) pyrrolidone, N-vinyl pyridine, N-vinyl piperidone , N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, and other N-vinylcarboxylic acids Examples include 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. .

  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 polyfunctional monomer other than the alkoxysilyl group-containing 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 product of (meth) acrylic acid and polyhydric alcohol such as pentaerythritol tri (meth) acrylate and dipentaerythritol hexa (meth) acrylate; polyfunctional vinyl compound such as divinylbenzene; diacetone acrylamide; (meth) acrylic acid Examples thereof include compounds having unsaturated double bonds having different reactivity such as allyl and vinyl (meth) 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.

  The copolymerizable monomer other than the alkoxysilyl group-containing monomer and the phosphate group-containing monomer is a monomer unit in either the (meth) acrylic copolymer (A) or the (meth) acrylic copolymer (B). Or may be contained only in one side. When these copolymerizable monomers are monofunctional monomers, the ratio is such that the viscosity of the emulsion does not become too high, and from the viewpoint of emulsion stability, the (meth) acrylic copolymer (A) or (meth) It is preferably 20% by weight or less, more preferably 10% by weight or less, and further preferably 5% by weight or less of the total monomer units of the acrylic copolymer (B). When the copolymerizable monomer is a polyfunctional monomer, the ratio is the total monomer of the (meth) acrylic copolymer (A) or (meth) acrylic copolymer (B) from the viewpoint of emulsion stability. It is preferably 5% by weight or less of the unit, more preferably 3% by weight or less, and further preferably 1% by weight or less.

  The aqueous dispersion of the (meth) acrylic copolymer (A) and the aqueous dispersion of the (meth) acrylic copolymer (B) are monomers containing a (meth) acrylic acid alkyl ester and a carboxyl group-containing monomer. It is obtained by polymerizing the components in water in the presence of a surfactant and a radical polymerization initiator. Examples of the form of polymerization include emulsion polymerization, suspension polymerization, and dispersion polymerization. In the case of emulsion polymerization, a polymer emulsion is used. In the case of suspension polymerization, a polymer suspension is used. In the case of dispersion polymerization, a polymer dispersion is used. can get. The type of adhesive polymer and the polymerization means are selected according to the type of adhesive. In addition, the surfactant is appropriately selected depending on each polymerization mode, and an emulsifier in the case of emulsion polymerization and a dispersant in the case of suspension polymerization.

  The aqueous dispersion in the water-dispersed pressure-sensitive adhesive of the present invention is preferably an emulsion-type pressure-sensitive adhesive using a polymer emulsion obtained by emulsion polymerization.

  The emulsion polymerization of the monomer component was performed by a conventional method. Thus, an aqueous dispersion (polymer emulsion) containing the (meth) acrylic copolymer (A) or the (meth) acrylic copolymer (B) 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, 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 ether sulfate ester salts, and the like. 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, commercially available products such as Aqualon KH-05, KH-10, KH-20 manufactured by Daiichi Kogyo Seiyaku Co., Ltd., ADEKA manufactured by Asahi Denka Kogyo Co., Ltd. Rear soap SR-10N, SR-20N, Latemu PD-104, etc. manufactured by Kao Corporation; Sulfosuccinate ester-based products (for example, Latemu S-120, S-120A, S-180P, Kao Corporation), S-180A, Elyonol JS-2 manufactured by Sanyo Chemical Co., Ltd.); alkyl phenyl ethers or alkyl phenyl esters (for example, Aqualon H-2855A, H-3855B, H manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) -3855C, H-3856, HS-05, HS-10, HS-20, HS-30, BC-0 , 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.) (Meta) Acrylate sulfate ester (commercially available products include, for example, Nippon Emulsifier Co., Ltd. Antox MS-60, MS-2N, Sanyo Chemical Industries Co., Ltd., Eleminol RS-30, etc.); Examples thereof include 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 containing the (meth) acrylic acid alkyl ester. 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 3 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. If it is less than 0.02 part by weight, the effect as a radical polymerization initiator may be reduced. If it exceeds 1 part by weight, a (meth) acrylic copolymer (A) related to an aqueous dispersion (polymer emulsion) (A ) Or (meth) acrylic copolymer (B) may have a reduced molecular weight, which may reduce the durability of the water-dispersed pressure-sensitive adhesive. 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 water-dispersed (meth) acrylic polymer as necessary, and a chain transfer agent usually used for emulsion polymerization is usually 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, the (meth) acrylic copolymer (A) or the (meth) acrylic copolymer (B) can be prepared as an aqueous dispersion (emulsion). Such water-dispersed (meth) acrylic copolymer (A) or (meth) acrylic copolymer (B) has an average particle size of, for example, 0.05 to 3 μm, preferably 0. 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.

  In order to maintain the dispersion stability of the aqueous dispersion, at least one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) according to the aqueous dispersion is The monomer unit contains a carboxyl group-containing monomer, but it is preferable to neutralize the carboxyl group-containing monomer. Neutralization can be performed, for example, with ammonia, alkali metal hydroxide, or the like.

  The water-dispersed (meth) acrylic copolymer (A) or (meth) acrylic copolymer (B) 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 water-dispersed pressure-sensitive adhesive composition for an optical film of the present invention is obtained by mixing an aqueous dispersion of the (meth) acrylic copolymer (A) and an aqueous dispersion of the (meth) acrylic copolymer (B). It contains in the range of a ratio (A) / (B) = 50-90 / 10-50 (solid content weight ratio). The mixing ratio is 100 (wt%) of the total weight of each solid content of the aqueous dispersion of the (meth) acrylic copolymer (A) and the aqueous dispersion of the (meth) acrylic copolymer (B). This is the ratio when Within this range, while using the aqueous dispersion of the (meth) acrylic copolymer (A) and the aqueous dispersion of the (meth) acrylic copolymer (B), while ensuring the adhesiveness of the pressure-sensitive adhesive. A decrease in cohesive force can be suppressed. That is, an aqueous dispersion of the (meth) acrylic copolymer (A) is contained in an amount of 50 to 90% by weight so that the total weight of each solid content is 100% by weight. An aqueous dispersion of the acrylic copolymer (B) is contained in an amount of 10 to 50% by weight. The aqueous dispersion (solid content weight ratio) of the (meth) acrylic copolymer (A) is preferably 60% by weight or more, and more preferably 70% by weight or more. When the aqueous dispersion (solid weight ratio) of the (meth) acrylic copolymer (A) is less than 50% by weight, the adhesiveness of the pressure-sensitive adhesive is lowered and humid peeling is likely to occur. On the other hand, the aqueous dispersion (solid content weight ratio) of the (meth) acrylic copolymer (A) is 90% by weight or less, more preferably 85% by weight or less, and further preferably less than 85% by weight. If the aqueous dispersion (solid weight ratio) of the (meth) acrylic copolymer (A) is less than 85% by weight, it has monomer units other than the (meth) acrylic acid alkyl ester and the carboxyl group-containing monomer. Even if not, the effect is good. When the aqueous dispersion (solid content weight ratio) of the (meth) acrylic copolymer (A) exceeds 90% by weight, the cohesive force of the pressure-sensitive adhesive is lowered, and peeling with time tends to occur.

  The water-dispersed pressure-sensitive adhesive composition of the present invention contains an aqueous dispersion of (meth) acrylic copolymer (A) and an aqueous dispersion of (meth) acrylic copolymer (B). The total solid content weight of each of these aqueous dispersions is 80% by weight or more, more preferably 90% by weight or more, and further 95% by weight of the solid content weight of the aqueous dispersion according to the water-dispersed pressure-sensitive adhesive composition for optical films. It is preferable to use it so that it may become 100% as mentioned above. That is, the aqueous dispersion of the water-dispersed pressure-sensitive adhesive composition for optical films includes an aqueous dispersion of (meth) acrylic copolymer (A) and an aqueous dispersion of (meth) acrylic copolymer (B). In addition to the liquid, other components can be used. 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.

  As said other component, a crosslinking agent can be contained as needed. Examples of the crosslinking agent used when the water-dispersed pressure-sensitive adhesive is a water-dispersed acrylic pressure-sensitive adhesive include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, metal chelates Commonly used materials such as a system cross-linking agent can be used. These cross-linking agents have the effect of reacting with a functional group introduced into the (meth) acrylic polymer and crosslinking by using a functional group-containing monomer.

  The blending ratio of the cross-linking agent is not particularly limited, but usually the solid content weight of the aqueous dispersion of the (meth) acrylic copolymer (A) and the aqueous dispersion of the (meth) acrylic copolymer (B). Is added at a ratio of about 10 parts by weight or less of the crosslinking agent (solid content) with respect to 100 parts by weight. The blending ratio of the crosslinking agent is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, and further preferably about 0.01 to 2 parts by weight. In addition, although a cohesive force can be given to an adhesive layer with a crosslinking agent, when a crosslinking agent is used, there exists a tendency for adhesiveness to worsen and it becomes easy to produce humid peeling, and in this invention, a crosslinking agent is not especially required.

  Furthermore, the water-dispersed pressure-sensitive adhesive composition 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 materials as necessary. Fillers made of powder, pigments, colorants (pigments, dyes, etc.), pH adjusters (acids or bases), antioxidants, UV absorbers, silane coupling agents, etc. do not depart from the purpose of the present invention. Various additives can be appropriately used within a range. 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 pressure-sensitive adhesive layer for an optical film of the present invention is formed from the water-dispersed pressure-sensitive adhesive composition. 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 composition 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 composition. 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 pressure-sensitive adhesive layer preferably has a haze value (H20) of 0 to 1% when the thickness of the pressure-sensitive adhesive layer is 20 μm, and has transparency required for the pressure-sensitive adhesive optical film. . The haze value (H20) is preferably 0 to 0.8%, more preferably 0 to 0.5%.

  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 an optical film, what is used for formation of image display apparatuses, such as a liquid crystal display device, is used, and the kind in particular is not restrict | 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 coloring 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.

Production Example 1
(Preparation of (meth) acrylic copolymer emulsion)
To the container, 950 parts of butyl acrylate and 50 parts of acrylic acid as raw materials were added and mixed to obtain a monomer mixture. Next, 24 parts of Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.), which is a reactive surfactant (anionic), and 382 parts of ion-exchanged water are added to 600 parts of the monomer mixture prepared at the above ratio. Using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), the mixture was stirred at 6000 (rpm) for 5 minutes to prepare a monomer emulsion.

  Next, 200 parts of the monomer emulsion prepared above and 330 parts of ion-exchanged water were charged into a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, a dropping funnel and a stirring blade, and then the reaction vessel was After sufficiently purging with nitrogen, 0.6 part of ammonium persulfate was added and polymerized at 60 ° C. for 1 hour with stirring. Subsequently, the remaining monomer emulsion was dropped into the reaction vessel at 60 ° C. over 3 hours and then polymerized for 3 hours to obtain a polymer emulsion having a solid content concentration of 46.4%. Next, after cooling the polymer emulsion to room temperature, 30 parts of 10% ammonia water was added to adjust the pH to 7.5, and a (meth) acrylic copolymer emulsion having a solid content of 45.3%. (1) was obtained.

Production Example 2
In Production Example 1, a monomer mixture of 680 parts of 2-ethylhexyl acrylate, 300 parts of methacrylic acid and 20 parts of acrylic acid was used as in Production Example 1 to obtain a solid content of 45.0%. An adjusted (meth) acrylic copolymer emulsion (2) was obtained.

Production Example 3
In Production Example 1, (meth) acrylic was adjusted to a solid content of 45.5% in the same manner as in Production Example 1 except that a monomer mixture of 950 parts of ethyl acrylate and 50 parts of acrylic acid was used as the monomer mixture. A system copolymer emulsion (3) was obtained.

Production Example 4
In Production Example 1, the solid content was adjusted to 45.4% in the same manner as in Production Example 1 except that a monomer mixture of 800 parts of butyl acrylate, 150 parts of methyl acrylate and 50 parts of acrylic acid was used as the monomer mixture. A (meth) acrylic copolymer emulsion (4) was obtained.

Production Example 5
In Production Example 1, as a monomer mixture, a monomer mixture of 900 parts of butyl acrylate, 50 parts of cyclohexyl methacrylate and 50 parts of acrylic acid was used in the same manner as in Production Example 1, and the solid content was 46.2%. A (meth) acrylic copolymer emulsion (5) was prepared.

Production Example 6
In Production Example 1, as a monomer mixture, 899.5 parts of butyl acrylate, 50 parts of cyclohexyl methacrylate, 50 parts of acrylic acid and 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM- 503) A (meth) acrylic copolymer emulsion (6) adjusted to a solid content of 45.6% was obtained in the same manner as in Production Example 1 except that 0.5 part of the monomer mixture was used.

Production Example 7
In Production Example 1, as a monomer mixture, 879.5 parts of butyl acrylate, 50 parts of cyclohexyl methacrylate, 50 parts of acrylic acid, mono [poly (propylene oxide) methacrylate] phosphate ester (manufactured by Rhodia Nikka Co., Ltd.) : Production Example, except that a monomer mixture of 20 parts of a trade name “Sipomer PAM-200” and 0.5 part of 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) was used. 1 to obtain a (meth) acrylic copolymer emulsion (7) adjusted to a solid content of 45.5%.

Production Example 8
In Production Example 1, as a monomer mixture, 629.5 parts of butyl acrylate, 300 parts of cyclohexyl methacrylate, 50 parts of acrylic acid, mono [poly (propylene oxide) methacrylate] phosphate ester (manufactured by Rhodia Nikka Co., Ltd.) : Production Example, except that a monomer mixture of 20 parts of a trade name “Sipomer PAM-200” and 0.5 part of 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) was used. 1 to obtain a (meth) acrylic copolymer emulsion (8) adjusted to a solid content of 45.5%.

Production Example 9
In Production Example 1, a monomer mixture of 530 parts of butyl acrylate, 420 parts of cyclohexyl methacrylate, and 50 parts of acrylic acid was used except that a monomer mixture was used, and the solid content was 45.5%. A (meth) acrylic copolymer emulsion (9) was prepared.

Production Example 10
In Production Example 1, the solid content was adjusted to 45.1% in the same manner as in Production Example 1 except that a monomer mixture of 900 parts of methyl methacrylate, 80 parts of butyl acrylate and 20 parts of acrylic acid was used as the monomer mixture. A (meth) acrylic copolymer emulsion (10) was obtained.

Production Example 11
In Production Example 1, as a monomer mixture, 900 parts of methyl methacrylate, 79 parts of butyl acrylate, 20 parts of acrylic acid, and 1 part of 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) A (meth) acrylic copolymer emulsion (11) adjusted to a solid content of 45.2% was obtained in the same manner as in Production Example 1 except that the above monomer mixture was used.

Production Example 12
In Production Example 1, a monomer mixture of 979 parts of t-butyl methacrylate, 20 parts of acrylic acid and 1 part of 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) A (meth) acrylic copolymer emulsion (12) adjusted to a solid content of 44.9% was obtained in the same manner as in Production Example 1 except that it was used.

Production Example 13
In Production Example 1, a monomer mixture of 979 parts of isobornyl methacrylate, 20 parts of acrylic acid and 1 part of 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) was used. A (meth) acrylic copolymer emulsion (12) adjusted to a solid content of 44.5% in the same manner as in Production Example 1 was obtained.

Production Example 14
In Production Example 1, as a monomer mixture, 730 parts of methyl methacrylate, 249 parts of butyl acrylate, 20 parts of acrylic acid, and 1 part of 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) A (meth) acrylic copolymer emulsion (14) adjusted to a solid content of 45.6% was obtained in the same manner as in Production Example 1 except that the monomer mixture was used.

Production Example 15
In Production Example 1, as a monomer mixture, 650 parts of methyl methacrylate, 329 parts of butyl acrylate, 20 parts of acrylic acid, and 1 part of 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) A (meth) acrylic copolymer emulsion (15) adjusted to a solid content of 45.6% was obtained in the same manner as in Production Example 1 except that the monomer mixture was used.

Production Example 16
In Production Example 1, as a monomer mixture, 250 parts of methyl methacrylate, 729 parts of butyl acrylate, 20 parts of acrylic acid and 1 part of 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) A (meth) acrylic copolymer emulsion (16) adjusted to a solid content of 45.7% was obtained in the same manner as in Production Example 1 except that the above monomer mixture was used.

Production Example 17
In Production Example 1, the solid content was adjusted to 45.2% in the same manner as in Production Example 1 except that 950 parts of 2-ethylhexyl acrylate and 50 parts of acrylic acid were used as the monomer mixture. A (meth) acrylic copolymer emulsion (17) was obtained.

Production Example 18
In Production Example 1, a monomer mixture of 950 parts of methyl methacrylate, 30 parts of 2-ethylhexyl acrylate, and 20 parts of acrylic acid was used in the same manner as in Production Example 1 except that a solid content of 45. A (meth) acrylic copolymer emulsion (18) adjusted to 3% was obtained.

Production Example 19
(Meth) acrylic prepared in Production Example 1 in the same manner as in Production Example 1 except that a monomer mixture of 950 parts of lauryl methacrylate and 50 parts of acrylic acid was used as the monomer mixture. A system copolymer emulsion (19) was obtained.

  Table 1 shows the glass transition temperatures (theoretical values based on the FOX equation) of the (meth) acrylic copolymer emulsions (1) to (19) obtained in Production Examples 1 to 19. Table 1 also shows the monomer components of each copolymer emulsion and their proportions (% by weight).

Example 1
(Preparation of water-dispersed pressure-sensitive adhesive composition)
In the (meth) acrylic copolymer emulsion (1) and the (meth) acrylic copolymer emulsion (10), the mixing ratio of (1) and (10) is (1) / (10) = 80/20. The mixture was mixed so as to have a solid content weight ratio of 2 to obtain a water-dispersed pressure-sensitive adhesive composition.

(Formation of adhesive layer and creation of adhesive polarizing plate)
The water-dispersed pressure-sensitive adhesive composition is applied to a release film (Mitsubishi Chemical Polyester Co., Ltd., Diafoil MRF-38, polyethylene terephthalate base material) with a die coater so that the thickness after drying is 20 μm. Then, it was dried at 120 ° C. for 5 minutes to form an adhesive layer. The pressure-sensitive adhesive layer was bonded to a polarizing plate (manufactured by Nitto Denko Corporation, product name SEG-DU) to prepare a pressure-sensitive adhesive polarizing plate.

Examples 2 to 16 and Comparative Examples 1 to 6
In Example 1, a water-dispersed pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that the type and ratio of the (meth) acrylic copolymer emulsion to be mixed were changed as shown in Table 1. . Further, using the water-dispersed pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer was formed and a pressure-sensitive adhesive polarizing plate was prepared in the same manner as in Example 1.

  In Table 1, except for Comparative Example 6, two types of (meth) acrylic copolymer emulsions are mixed, but the lower Tg is the lower Tg (meth) acrylic copolymer (A). The higher Tg is the high Tg (meth) acrylic copolymer (B).

  The following evaluation was performed about the adhesive polarizing plate obtained by the said Example and comparative example. The evaluation results are shown in Table 2.

[Humidification durability <humidification peeling>]
The adhesive polarizing plate of each example and each comparative example was cut into a size of 15 inches, and this was pasted on a non-alkali glass plate (Corning # 1737, Corning Corp.) having a thickness of 0.7 mm. And left in an autoclave at 50 ° C. and 0.5 MPa for 15 minutes. Thereafter, 60 ° C., 90% R.D. H. Immediately after taking out for 500 hours in an ambient atmosphere and taking out to room temperature conditions (23 ° C., 55% RH), the degree of peeling between the treated pressure-sensitive adhesive polarizing plate and the alkali-free glass was visually observed. And evaluated according to the following criteria.
5: No peeling occurred.
4: The peeling has occurred in a portion within 0.5 mm from the end of the adhesive polarizing plate.
3: The peeling has generate | occur | produced in the location within 1.0 mm from the edge part of an adhesion type polarizing plate.
2: The peeling has occurred in a portion within 3.0 mm from the end of the adhesive polarizing plate.
1: Stripping occurs at a position of 3.0 mm or more from the end of the adhesive polarizing plate.

[High temperature humidification durability <Aging over time>]
The adhesive polarizing plate of each example and each comparative example was cut into a size of 15 inches, and this was pasted on a non-alkali glass plate (Corning # 1737, Corning Corp.) having a thickness of 0.7 mm. And left in an autoclave at 50 ° C. and 0.5 MPa for 15 minutes. Thereafter, 85 ° C., 85% R.D. H. Immediately after being treated for 100 hours in an ambient atmosphere and taken out to room temperature conditions (23 ° C., 55% RH), the degree of peeling between the treated pressure-sensitive adhesive polarizing plate and the alkali-free glass was visually observed. And evaluated according to the following criteria. In any case, the evaluation at this stage was “5”, and no peeling occurred. Next, after taking out to room temperature conditions (23 ° C., 55% RH) and storing for 240 hours, the degree of peeling between the treated pressure-sensitive adhesive polarizing plate and the non-alkali glass was visually confirmed, and the following criteria were used. evaluated.
5: No peeling occurred.
4: The peeling has occurred in a portion within 0.5 mm from the end of the adhesive polarizing plate.
3: The peeling has generate | occur | produced in the location within 1.0 mm from the edge part of an adhesion type polarizing plate.
2: The peeling has occurred in a portion within 3.0 mm from the end of the adhesive polarizing plate.
1: Stripping occurs at a position of 3.0 mm or more from the end of the adhesive polarizing plate.

[Haze]
The 20 μm thick adhesive layer provided on the release film obtained in each example was cut into 50 mm × 50 mm. Thereafter, the pressure-sensitive adhesive layer was peeled off from the release film, and in an atmosphere of 25 ° C., using “HAZEMETER HM-150 type” manufactured by Murakami Color Research Laboratory Co., Ltd., according to JISK-7136, The haze value (%) was measured.

  From Tables 1 and 2, the pressure-sensitive adhesive optical films (pressure-sensitive polarizing plates) of the examples have good transparency, and can satisfy both humidification and long-time peeling, and have good humidification durability and high-temperature humidification durability. I understand. On the other hand, Comparative Examples 1 to 5 do not satisfy either the glass transition temperature or the mixing ratio according to the (meth) acrylic copolymer (A) or (B) of the present application. I am not satisfied with both.

  In the table, BA: butyl acrylate (228.15K), AA: acrylic acid (379K.15), 2EHA: 2-ethylhexyl acrylate (218.15K), EA: ethyl acrylate (253.15K), CHMA : Cyclohexyl methacrylate (339.15K), KBM503: 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503), PAM200: mono [poly (propylene oxide) methacrylate] phosphoric acid Esters (Rhodia Nikka Co., Ltd .: trade name “SipomerPAM-200” (273.15K), MMA: methyl methacrylate (278.15K), t-BMA: t-butyl methacrylate (380.15K), IBXMA : Isobonyl methacrylate (453.15K), MA:. Showing a lauryl methacrylate (208.15K) The temperature in the parentheses is used to calculate a glass transition temperature, the glass transition temperature of the homopolymer of each monomer (K).

Claims (9)

(Meth) acrylic acid alkyl ester is contained as a monomer unit, and the glass transition temperature (however, the glass transition temperature is calculated based on the monofunctional monomer in the monomer unit) exceeds −45 ° C. and is 0 ° C. or less. An aqueous dispersion of (meth) acrylic copolymer (A);
(Meth) acrylic acid alkyl ester is contained as a monomer unit, and the glass transition temperature (where the glass transition temperature is calculated based on the monofunctional monomer in the monomer unit) is from 0 ° C. to 180 ° C. (meta ) Containing an aqueous dispersion of the acrylic copolymer (B), and
At least one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) contains a carboxyl group-containing monomer as a monomer unit,
The difference between the glass transition temperature of the (meth) acrylic copolymer (A) and the glass transition temperature of the (meth) acrylic copolymer (B) is 50 ° C. or more, and
The mixing ratio of the aqueous dispersion of the (meth) acrylic copolymer (A) and the aqueous dispersion of the (meth) acrylic copolymer (B) is (A) / (B) = 50 / 50- It contains in the range of 90/10 (solid content weight ratio), The water-dispersed adhesive composition for optical films characterized by the above-mentioned.
At least one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) is an alkoxysilyl group-containing monomer (provided that the alkoxysilyl group-containing monomer is a monomer unit) The ratio of the alkoxysilyl group-containing monomer is (meth) acrylic copolymer (A) or (meth) acrylic copolymer. polymer (B) according to claim 1 optical film water-dispersible pressure-sensitive adhesive composition, wherein it is 0.001% by weight of the total monomer units.   The at least one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) contains a phosphate group-containing monomer as a monomer unit. 3. The water-dispersed pressure-sensitive adhesive composition for optical films according to 1 or 2.   The proportion of the phosphate group-containing monomer is 0.1 to 20% by weight of the total monomer units of the (meth) acrylic copolymer (A) or (meth) acrylic copolymer (B). The water-dispersed pressure-sensitive adhesive composition for optical films according to claim 3.   The aqueous dispersion of the (meth) acrylic copolymer (A) and the aqueous dispersion of the (meth) acrylic copolymer (B) are polymer emulsions obtained by emulsion polymerization. Item 5. The water-dispersed pressure-sensitive adhesive composition for optical films according to any one of Items 1 to 4.   An optical film pressure-sensitive adhesive layer formed by applying the water-dispersed pressure-sensitive adhesive composition for an optical film according to claim 1 and then drying.   The pressure-sensitive adhesive layer for optical films according to claim 6, wherein the pressure-sensitive adhesive layer has a haze value (H20) of 0 to 1% when the pressure-sensitive adhesive layer has a thickness of 20 µm.   An adhesive optical film, wherein the optical film pressure-sensitive adhesive layer according to claim 6 or 7 is laminated on at least one side of the optical film.   An image display device comprising at least one adhesive optical film according to claim 8.