JP5758088B2 - Optical film adhesive composition, optical film adhesive layer, adhesive 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 retardation plate, a front plate, an optical compensation film, a brightness enhancement film, and a laminate of these 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. For example, as an organic solvent-type pressure-sensitive adhesive that can ensure durability such as peeling, it contains 0.01 to 1 part by weight of an isocyanate compound with respect to 100 parts by weight of a (meth) acrylic polymer into which a functional group has been introduced. It has been proposed to use an adhesive composition for optical members whose gel fraction is controlled by crosslinking (Patent Document 1).

  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. Moreover, since the pressure-sensitive adhesive layer formed of the water-dispersed pressure-sensitive adhesive composition is formed of emulsion particles and the like, a particle interface exists as the layer structure, and the composition of Patent Document 1 is water-dispersed. Even if it is applied to the pressure-sensitive adhesive composition to form a pressure-sensitive adhesive layer, the humidification durability cannot be satisfied.

  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).

JP 2002-091500 A JP 2002-309212 A JP 2007-186661 A

  The water-dispersed pressure-sensitive adhesives of Patent Documents 2 and 3 are satisfactory for durability after a certain humidification test. However, the water-dispersed pressure-sensitive adhesives of Patent Documents 2 and 3 described above are peeling that occurs when the pressure-sensitive optical film is taken out from a high-temperature humidified environment at room temperature and then stored for a long time (hereinafter, this peeling is referred to as time-lapse). It has been newly found that it is not enough to suppress the effect.

  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 from 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 provides (meth) acrylic acid alkyl ester (a), and
Aqueous dispersion of (meth) acrylic copolymer (A) containing as a monomer unit a reversible monomer (b) having a functional group (x1) capable of causing a reversible reaction related to dehydration and hydrolysis reactions Because
The ratio of the (meth) acrylic acid alkyl ester (a) is 67 to 99.9% by weight of the total monomer units of the (meth) acrylic copolymer (A),
An aqueous dispersion of (meth) acrylic copolymer (A) in which the ratio of reversible monomer (b) is 0.1 to 10% by weight of the total monomer units of (meth) acrylic copolymer (A). ,
And a cross-linking agent (B) having at least two functional groups (x2) in the molecule that cause a reversible reaction related to dehydration and hydrolysis with respect to the functional group (x1) of the reversible monomer (b). It is related with the water-dispersed adhesive composition for optical films characterized by containing.

  In the water-dispersed pressure-sensitive adhesive composition for optical films, the reversible monomer (b) is preferably an aldehyde group-containing monomer or a keto group-containing monomer.

  In addition, the (meth) acrylic copolymer (A) has, as a monomer unit, in addition to the (meth) acrylic acid alkyl ester (a) and the reversible monomer (b), It is preferable that the content of the carboxyl group-containing monomer is 0.1 to 10% by weight of the total monomer units of the (meth) acrylic copolymer (A).

  In the water-dispersed pressure-sensitive adhesive composition for optical films, when the reversible monomer (b) is an aldehyde group-containing monomer or a keto group-containing monomer, the functional group (x2) of the crosslinking agent is preferably a hydrazino group. .

  In the water-dispersed pressure-sensitive adhesive composition for optical films, the (meth) acrylic copolymer (A) contains an alkoxysilyl group-containing monomer (c) as a monomer unit, and the alkoxysilyl group It is preferable that the ratio of a containing monomer is 0.001-1 weight% of the total monomer unit of (meth) acrylic-type copolymer (A).

  In the water-dispersed pressure-sensitive adhesive composition for optical film, the (meth) acrylic copolymer (A) contains a phosphate group-containing monomer as a monomer unit, and the phosphate group-containing monomer The proportion is preferably 0.1 to 20% by weight of the total monomer units of the (meth) acrylic copolymer (A).

  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 is
60 ° C., 7% R.F. H. Elongation at (L60) is 250% or less,
60 ° C., 7% R.F. H. Elongation at room temperature (L60) and 60 ° C., 90% R.V. H. It is preferable that the ratio {(L60-90) / (L60)} to the elongation (L60-90) at 1.5 is 1.5 or more.

However, the elongation rate was determined by forming the pressure-sensitive adhesive layer into a cylindrical test piece having a cross-sectional area of 4.6 mm ² and a length of 30 mm, and subjecting the test piece to 60 ° C., 7% R.D. H. Or 60 ° C., 90% R.D. H. The length L0 (mm) after being left for 1 hour in the environment of, and then, one end of the test piece was fixed, a 12 g weight was attached to the other end of the test piece, and the test piece was 60 ° C., 7% R. H. Or 60 ° C., 90% R.D. H. From the length L1 (mm) of the test piece after being dropped for 2 hours in the environment of
Elongation rate (%) = {(L1-L0) / L0} × 100.

  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.

  Usually, the means to increase the cohesive strength of the acrylic adhesive layer is to introduce an internal cross-linked structure using a polyfunctional monomer in the acrylic polymer, or to introduce a functional group such as a carboxyl group or a hydroxyl group into the acrylic polymer. And a method of introducing an external cross-linking structure with a cross-linking agent having a functional group reactive with the functional group (for example, a carbodiimide compound, an oxazoline compound, an epoxy compound, an aziridine compound, an isocyanate compound). Has been. In the method of introducing the crosslinked structure, once the crosslinked structure is formed, the bond related to the crosslinked structure is rarely broken. Therefore, when an optical film having a pressure-sensitive adhesive layer having a crosslinked structure formed on glass is taken out from a high-temperature humidified environment (for example, 85 ° C., 85% RH) at room temperature and stored for a long time. There is little change in the cross-linked structure. Therefore, according to the pressure-sensitive adhesive layer having a crosslinked structure, it is possible to improve peeling over time. However, according to the pressure-sensitive adhesive layer having a crosslinked structure, the whole pressure-sensitive adhesive layer becomes hard. The hardened pressure-sensitive adhesive layer has poor adhesion to the glass interface. For this reason, the pressure-sensitive adhesive layer into which the crosslinked structure has been introduced cannot satisfy the humid peeling caused in a humid environment (for example, 60 ° C., 90% RH).

  In the present invention, in order to impart cohesive force to the pressure-sensitive adhesive layer, the water-dispersed pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer has a functional group (x1) that causes a reversible reaction related to dehydration and hydrolysis reactions. A reversible reaction related to dehydration and hydrolysis reaction on the functional group (x1) together with an aqueous dispersion of the (meth) acrylic copolymer (A) having the reversible monomer (b) as a monomer unit. A crosslinking agent (B) having at least two functional groups (x2) in the molecule is used. As described above, as the water-dispersed pressure-sensitive adhesive composition, the functional group (x1) of the (meth) acrylic copolymer (A) and the functional group (x2) of the crosslinking agent are dehydrated and hydrolyzed. By using a combination that causes a reversible reaction related to the reaction, the pressure-sensitive adhesive layer formed by the water-dispersed pressure-sensitive adhesive composition has excellent cohesive strength while maintaining the adhesive force to the adherend. It is possible to suppress the humidified peeling and the aging peeling.

  As described above, the crosslinked structure in the pressure-sensitive adhesive layer of the present invention is formed by the reaction of the functional group (x1) and the functional group (x2) that cause a reversible reaction related to dehydration and hydrolysis reactions. The reversible reaction relates to a crosslinking reaction based on a dehydration reaction in the absence of water and a decrosslinking reaction based on a hydrolysis reaction in the presence of water. In such a pressure-sensitive adhesive layer that can undergo a reversible reaction, a de-crosslinking reaction occurs in a humidified environment, the pressure-sensitive adhesive layer becomes soft, adhesion to the glass interface is unlikely to decrease, and humidification peeling is suppressed. . In addition, when taken out from a high-temperature humidified environment at room temperature and stored for a long period of time, the pressure-sensitive adhesive layer becomes hard because the moisture decreases, the cohesive layer becomes hard, the cohesive force is improved, and the cohesive layer is agglomerated. It becomes difficult to break down, and the peeling over time can be suppressed.

  The water-dispersed pressure-sensitive adhesive composition for optical films of the present invention has a (meth) acrylic acid alkyl ester (a) and a functional group (x1) capable of causing a reversible reaction related to dehydration and hydrolysis reactions. Dehydration and hydrolysis reaction of the aqueous dispersion of the (meth) acrylic copolymer (A) containing the reversible monomer (b) as a monomer unit and the functional group (x1) of the reversible monomer (b). A cross-linking agent (B) having at least two functional groups (x2) in the molecule that cause a reversible reaction related to 1.

  The (meth) acrylic acid alkyl ester (a) used for the (meth) acrylic polymer (A) preferably has a water solubility in a certain range from the viewpoint of emulsion polymerization reactivity. The main component is preferably a (meth) acrylic acid alkyl ester having a number of 1 to 18. Specific examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and t- (meth) acrylic acid. Butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, Examples include alkyl acrylate esters such as stearyl acrylate. These can be used alone or in combination of two or more. Among these, the alkyl group such as propyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate has 3 to 9 carbon atoms. (Meth) acrylic acid alkyl esters are preferred. 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 (a) contains 67 to 99.9% by weight of the total monomer units of the (meth) acrylic polymer (A). Preferably it is 70-99.8 weight%, Furthermore, it is preferable that it is 80-99.5 weight%.

  The reversible monomer (b) used in the (meth) acrylic polymer (A) is a relationship between the functional group (x1) of the reversible monomer (b) and the functional group (x2) of the crosslinking agent (B). Thus, these functional groups are selected to be a combination capable of causing a reversible reaction related to dehydration and hydrolysis reactions. Examples of combinations that generate a reversible reaction related to dehydration and hydrolysis include hydrazino group and semicarbazide group for aldehyde group or keto group. For the carboxyl group, a metal salt, a metal chelate compound and the like related to at least a divalent or higher metal can be used. In addition, the functional group that generates a reversible reaction related to the dehydration and hydrolysis reaction of the present invention includes a metal that can provide an ionic state. For example, a bivalent metal has two functional groups.

  The reversible monomer (b) contains 0.1 to 10% by weight of the total monomer units of the (meth) acrylic polymer (A). It is preferably 0.3 to 5% by weight, more preferably 0.5 to 3% by weight, and further preferably 0.5 to 2% by weight. If it is less than 0.1% by weight, the effect on crosslinking cannot be sufficiently obtained, and peeling with time occurs. On the other hand, if it exceeds 10% by weight, the degree of cross-linking of the pressure-sensitive adhesive layer becomes too high, and the pressure-sensitive adhesive layer becomes too hard due to the partially crosslinked structure even under humidified conditions, resulting in a decrease in interfacial adhesion. Humidification peeling occurs.

  The functional group (x1) possessed by the reversible monomer (b) is likely to cause a reversible reaction related to dehydration and hydrolysis due to the functional group (x2), and is difficult to undergo a crosslinking reaction in the presence of water. From the viewpoint of good stability of the aqueous dispersion, for example, an aldehyde group, a keto group, and a carboxyl group are preferable. Accordingly, the reversible monomer (b) is preferably an aldehyde group-containing monomer, a keto group-containing monomer, or a carboxyl group-containing monomer. In particular, as the reversible monomer (b), an aldehyde group-containing monomer or a keto group-containing monomer is preferably used.

  Examples of the aldehyde group-containing monomer include those having a radical polymerizable unsaturated double bond such as an aldehyde group, a (meth) acryloyl group, and a vinyl group. Examples include (meth) acrolein, N-vinylformamide, formylstyrene, and the like.

  Examples of the keto group-containing monomer include those having a radical polymerizable unsaturated double bond such as a keto group, a (meth) acryloyl group, and a vinyl group. For example, 4-7 such as acetoacetoxyethyl (meth) acrylate, acetoacetoxybutyl (meth) acrylate, diacetone (meth) acrylamide, diacetone (meth) acrylate, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone And vinyl alkyl ketones having the following carbon atoms.

  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.

  In addition to the (meth) acrylic acid alkyl ester (a) and the reversible monomer (b), the (meth) acrylic copolymer (A) includes a stabilized aqueous dispersion and an optical film of an adhesive layer. For the purpose of improving adhesion to a substrate such as, and further improving initial adhesion to an adherend, a polymerizable functional group related to an unsaturated double bond such as a (meth) acryloyl group or a vinyl group is added. One or more kinds of copolymerization monomers can be introduced by copolymerization.

  When a carboxyl group-containing monomer is not used as the reversible monomer (b), it is preferable to use a carboxyl group-containing monomer as the copolymerizable monomer. In particular, when an aldehyde group-containing monomer or a keto group-containing monomer is used as the reversible monomer (b), it is preferable to use a carboxyl group-containing monomer as a copolymerization monomer. As the carboxyl group-containing monomer, those exemplified above are used. The carboxyl group-containing monomer is also exemplified as the reversible monomer (b), but when the carboxyl group does not function as the reversible monomer (b) in relation to the functional group of the crosslinking agent, In order to improve adhesion and impart stability to the emulsion, it is preferable to use a carboxyl group-containing monomer.

  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), more preferably 0.5 to 7% by weight, and further 1 to 5%. It is preferable that it is weight%. 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.

  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 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 proportion of the alkoxysilyl group-containing monomer is preferably 0.001 to 1% by weight, more preferably 0.01 to 0.5% by weight, based on the total monomer units of the (meth) acrylic copolymer (A). Further, it is 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 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). 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. On the other hand, if it exceeds 20% by weight, it is not preferable from the viewpoint of polymerization stability.

  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 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 ) Compounds having unsaturated double bonds with different reactivity, 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.

  When the copolymerizable monomer other than the alkoxysilyl group-containing monomer and phosphoric acid group-containing monomer is a monofunctional monomer, the proportion of the monomer does not increase the viscosity of the emulsion. ) It is preferably 20% by weight or less of the total monomer units of the acrylic copolymer (A), 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 thereof is preferably 5% by weight or less of the total monomer units of the (meth) acrylic copolymer (A) from the viewpoint of emulsion stability. Further, it is preferably 3% by weight or less, more preferably 1% by weight or less.

  The aqueous dispersion of the (meth) acrylic copolymer (A) contains a monomer component containing a (meth) acrylic acid alkyl ester (a) and a reversible monomer (b) as a surfactant and a radical polymerization initiator. It is obtained by polymerizing in water in the presence. 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) 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, 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 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 (a) and the reversible monomer (b). preferable. 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 ) May decrease, and the durability of the water-dispersed pressure-sensitive adhesive may decrease. 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) can be prepared as an aqueous dispersion (emulsion). The average particle diameter of such a water-dispersed (meth) acrylic copolymer (A) 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.

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

  In general, the water-dispersed (meth) acrylic copolymer (A) 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 optical films of the present invention contains an aqueous dispersion of the (meth) acrylic copolymer (A) and a crosslinking agent (B). The crosslinking agent (B) is a compound having in the molecule at least two functional groups (x2) that cause a reversible reaction related to dehydration and hydrolysis with respect to the functional group (x1) of the reversible monomer (b). It is. The functional group (x2) is selected so as to be a combination that causes a reversible reaction related to dehydration and hydrolysis reactions in relation to the functional group (x1) of the reversible monomer (b).

  When the reversible monomer (b) is, for example, an aldehyde group-containing monomer or a keto group-containing monomer, examples of the crosslinking agent having a functional group (x2) include hydrazine-based crosslinking agents having at least two hydrazino groups and semicarbazide groups. Is preferred. Examples of compounds having at least two hydrazino groups include polyhydrazides of aliphatic polybasic acids such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, and sebacic acid dihydrazide; aromatic acids Polyhydrazide of polybasic acid; polyhydrazide of polyacrylic acid; polyhydrazide of aromatic hydrocarbon; hydrazine-pyridine derivative; polyhydrazide of unsaturated polybasic acid such as maleic acid dihydrazide; polyhydrazide carbonate and the like. In addition, as the compound having at least two semicarbazide groups, for example, a semicarbazide compound such as an aliphatic, alicyclic, aromatic polysemicarbazide, or the like can be used.

When the reversible monomer (b) is, for example, a carboxyl group-containing monomer, examples of the crosslinking agent having a functional group (x2) include metal salts and metal chelate compounds that can provide at least a divalent metal ion. Examples of the metal salt include zinc ammonium acetate, zinc ammonium carbonate, and zirconyl ammonium carbonate. As a metal chelate compound, the metal chelate compound of the element chosen from Ti, Zr, or Al is mentioned, for example. As a specific example of the metal chelate compound, when the metal element M is titanium or zirconium element, it is represented by the general formula (R ³ ) ^4-n M (R ⁴ ) ⁿ , and when M is an aluminum element, Alkoxide compound or alkoxyl group-substituted alkoxide compound represented by the general formula (R ³ ) ^3-m M (R ⁴ ) ^m [wherein n is an integer of 2 to 4, and m is an integer of 2 to 3; R ³ represents a substituent such as an ethyl group, an amyl group, a phenyl group, a vinyl group, a β- (3,4-epoxycyclohexyl) group, a γ-mercaptopropyl group, and an aminoalkyl group, and R ⁴ usually has the number of carbon atoms. 1 to 8 alkoxy groups (for example, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, n-pentoxy group) Si group, isopentoxy group, n-hexoxy group, n-heptoxy group, n-octoxy group, etc.) or alkoxy-substituted alkoxy groups having 2 to 10 carbon atoms in total (for example, methoxymethoxy group, methoxyethoxy group, ethoxybutoxy group) A dicarboxylic acid such as maleic acid; a ketone alcohol such as diacetone alcohol; a diketone such as acetylacetone; a ketone ester such as ethyl acetoacetate; a diester such as ethyl malonate; Salicylic acid; salicylaldehyde; phenols having two or more phenolic hydroxyl groups such as catechol and pyrogallol; alkanolamines such as triethanolamine, diethanolamine and dimethylamino alcohol as ligands Obtained by caulking together, two or more, and preferably coordination compounds having two or three metal alkoxide bonds (including alkoxy-substituted alkoxide bond) (complex compound).

  The blending ratio of the crosslinking agent (B) is not particularly limited, but usually 1 equivalent of the functional group (x1) of the reversible monomer (b) contained as a monomer unit in the (meth) acrylic copolymer (A). On the other hand, it is preferable that the functional group (x2) of the cross-linking agent (B) is blended so that the amount of the functional group (x2) is 0.05 to 3 equivalents, from the viewpoint of suppressing the generation of both the humid peeling and the aging peeling. If it is less than 0.05 equivalent, the effect of crosslinking may not be sufficiently obtained. If it exceeds 3 equivalents, the degree of cross-linking becomes too high, and the pressure-sensitive adhesive layer becomes too hard due to the cross-linking structure that remains partly even under humidification conditions, and there is a possibility that the interfacial adhesion is lowered and humidified peeling occurs. 0.1-2 equivalent is preferable and, as for the mixture ratio of a crosslinking agent (B), 0.2-1 equivalent is more preferable.

  In addition, another crosslinking agent can be used with a crosslinking agent (B). As said other crosslinking agent, what is generally used, such as an isocyanate type crosslinking agent, an epoxy type crosslinking agent, an oxazoline type crosslinking agent, an aziridine type crosslinking agent, a carbodiimide type crosslinking 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. However, although these cross-linking agents can impart cohesive force to the pressure-sensitive adhesive layer, the use of the cross-linking agent tends to result in poor adhesion and prone to humid peeling, and the use ratio thereof is (meth) acrylic copolymer. It is preferable that it is 0.5 weight part or less with respect to 100 weight part of solid content of the aqueous dispersion of a coalescence (A).

  The water-dispersed pressure-sensitive adhesive composition of the present invention contains an aqueous dispersion of a (meth) acrylic copolymer (A) and a crosslinking agent (B). 80% by weight or more, more preferably 90% by weight or more, further 95% by weight or more of the solid content of the aqueous dispersion according to the water-dispersed pressure-sensitive adhesive composition for film. Is preferred. 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.

  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 was measured by the above-described method, under an environment of 60 ° C., 7% R.D. H. Elongation (L60) is 250% or less, 60 ° C., 7% R.V. H. Elongation at room temperature (L60) and 60 ° C., 90% R.V. H. It is preferable that the ratio {(L60-90) / (L60)} to the elongation (L60-90) is 1.5 or more. The measurement method is described in detail in the examples. The elongation (L60) is preferably 230% or less, and more preferably 200% or less. When the elongation (L60) is 250% or less, the cohesive force of the pressure-sensitive adhesive layer is good, which is preferable for suppressing peeling over time. The ratio {(L60-90) / (L60)} is preferably 1.8 or more, and more preferably 2 or more. If the ratio is 1.5 or more, the pressure-sensitive adhesive layer is less likely to be soft under humidification conditions, which is preferable for preventing humid peeling due to a decrease in adhesive strength.

The pressure-sensitive adhesive layer preferably has a gel fraction of 70 to less than 95% by weight. The gel fraction is preferably 75 to 93% by weight, more preferably 80 to 90% by weight. Setting the gel fraction to 70% by weight or more is preferable in that the cohesive strength of the pressure-sensitive adhesive layer is good and the peeling with time is suppressed. It is preferable that the gel fraction is less than 95% by weight because the pressure-sensitive adhesive layer does not become too hard, the adhesiveness with the glass interface can be secured, and the moisture peeling is suppressed. The gel fraction is measured by the following method.
<Measurement of gel fraction>
About 0.1 g of the pressure-sensitive adhesive layer was taken and weighed to measure the weight W ₁ (g). Next, the pressure-sensitive adhesive layer was immersed in about 50 ml of ethyl acetate at 23 ° C. for 7 days, and then the soluble component was extracted. Then removed the adhesive layer from ethyl acetate, which was dried for 2 hours at 120 ° C., was measured total weight W _{2 (g).} From these measurements,
The following formula: gel fraction (% by weight) = [(W ₁ −W ₂ ) / W ₁ ] × 100
Was calculated as the gel fraction (% by weight) of the pressure-sensitive adhesive layer.

  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, 940 parts of butyl acrylate, 50 parts of acrylic acid and 10 parts of acetoacetoxyethyl methacrylate were added and mixed as raw materials to obtain a monomer mixture. Next, 40 parts of Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.), which is a reactive surfactant (anionic), and 635 parts of ion-exchanged water are added to 1000 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 552 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, ammonia water having a concentration of 10% was added to adjust the pH to 8, and a (meth) acrylic copolymer emulsion (1) having a solid content of 45.2% was obtained. Obtained.

Production Example 2
In Production Example 1, as a monomer mixture, 939.5 parts of butyl acrylate, 50 parts of acrylic acid, 10 parts of acetoacetoxyethyl methacrylate and 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM- 503) A (meth) acrylic copolymer emulsion (2) adjusted to a solid content of 45.3% was obtained in the same manner as in Production Example 1, except that 0.5 part of the monomer mixture was used.

Production Example 3
In Production Example 1, as the monomer mixture, 919.5 parts of butyl acrylate, 50 parts of acrylic acid, 10 parts of acetoacetoxyethyl methacrylate, 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM- 503) Manufacture except that a monomer mixture of 0.5 part and 20 parts of mono [poly (propylene oxide) methacrylate] phosphate ester (Rhodia Nikka Co., Ltd .: trade name “Sipomer PAM-200”) was used. In the same manner as in Example 1, a (meth) acrylic copolymer emulsion (3) adjusted to a solid content of 45.3% was obtained.

Production Example 4
In Production Example 1, as a monomer mixture, butyl acrylate 919.5 parts, acrylic acid 50 parts, diacetone acrylamide 10 parts, 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) Production Example 1 except that a monomer mixture of 0.5 part and 20 parts of mono [poly (propylene oxide) methacrylate] phosphate ester (Rhodia Nikka Co., Ltd .: trade name “Sipomer PAM-200”) was used. In the same manner as above, a (meth) acrylic copolymer emulsion (4) adjusted to a solid content of 45.3% was obtained.

Production Example 5
In Production Example 1, as a monomer mixture, 849.5 parts of butyl acrylate, 50 parts of acrylic acid, 80 parts of acetoacetoxyethyl methacrylate, 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM- 503) Manufacture except that a monomer mixture of 0.5 part and 20 parts of mono [poly (propylene oxide) methacrylate] phosphate ester (Rhodia Nikka Co., Ltd .: trade name “Sipomer PAM-200”) was used. In the same manner as in Example 1, a (meth) acrylic copolymer emulsion (5) adjusted to a solid content of 45.4% was obtained.

Production Example 6
In Production Example 1, as a monomer mixture, 915 parts of butyl acrylate, 50 parts of acrylic acid, 10 parts of acetoacetoxyethyl methacrylate, 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) Same as Production Example 1 except that a monomer mixture of 5 parts and 20 parts of mono [poly (propylene oxide) methacrylate] phosphate ester (Rhodia Nikka Co., Ltd .: trade name “Sipomer PAM-200”) was used. Thus, a (meth) acrylic copolymer emulsion (6) adjusted to a solid content of 45.4% was obtained.

Production Example 7
In Production Example 1, as a monomer mixture, 929.5 parts of butyl acrylate, 50 parts of acrylic acid, 0.5 part of 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503) and mono [Poly (propylene oxide) methacrylate] Phosphate ester (manufactured by Rhodia Nikka Co., Ltd .: trade name “Sipomer PAM-200”) Solid content as in Production Example 1 except that 20 parts of the monomer mixture was used A (meth) acrylic copolymer emulsion (7) adjusted to 45.3% was obtained.

  Table 1 shows the monomer components, the ratio (% by weight), and the solid content (% by weight) of the (meth) acrylic copolymer emulsions (1) to (7) obtained in Production Examples 1 to 7.

Example 1
(Preparation of water-dispersed pressure-sensitive adhesive composition)
As a cross-linking agent, 0.16 part of adipic acid dihydrazide (ADH, manufactured by Nippon Kasei Co., Ltd.) was added to 100 parts of the solid content of the (meth) acrylic copolymer emulsion (1). The amount of adipic acid dihydrazide was adjusted so that the hydrazino group was 0.2 equivalent relative to 1 equivalent of the keto group in the (meth) acrylic copolymer emulsion (1).

(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. A polarizing plate (Nitto Denko Corporation) provided with an undercoat layer having a film thickness of 500 nm formed from an undercoat agent (Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd.) containing an oxazoline copolymer. The product was transferred to a product name SEG-DU) to prepare an adhesive polarizing plate.

Examples 2 to 9 and Comparative Examples 1 to 3
A water-dispersed pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the type of (meth) acrylic copolymer emulsion to be mixed and the type of crosslinking agent were changed as shown in Table 1. Obtained. 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.

  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.

[Growth rate]
In each example, from a water-dispersed pressure-sensitive adhesive composition similar to the water-dispersed pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer, a cylindrical test piece (pressure-sensitive adhesive having a cross-sectional area of 4.6 mm ² and a length of 30 mm is used. Layer). Subsequently, the test piece was subjected to 60 ° C., 7% R.D. H. Or 60 ° C., 90% R.D. H. The length L0 (mm) after being left for 1 hour in the environment was measured. Thereafter, one end of the test piece was fixed, a 12 g weight was attached to the other end of the test piece, and the test piece was placed at 60 ° C., 7% R.D. H. Or 60 ° C., 90% R.D. H. The length L1 (mm) of the test piece after being dropped for 2 hours in the environment of was measured.
From the above results, elongation (%) = {(L1-L0) / L0} × 100 was calculated.
60 ° C., 7% R.F. H. When measured by the elongation rate (L60), the environment is 60 ° C., 90% R.D. H. The ratio {(L60-90) / (L60)} was determined with the elongation rate (L60-90) as the case measured by.

[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 Table 1, it can be seen that the pressure-sensitive adhesive optical films (pressure-sensitive polarizing plates) of the examples have good transparency, satisfy both the moisture peeling and the aging peeling, and have good humidification durability and high temperature humidification durability. On the other hand, Comparative Example 1 uses the same hydrazine-based crosslinking agent as in Examples, but the functional group of the crosslinking agent and the functional group of the (meth) acrylic copolymer are reversible related to dehydration and hydrolysis reactions. Since it is not a combination that causes a general reaction, the peeling over time cannot be satisfied. Moreover, in Comparative Examples 2 and 3, the cross-linking agent is not used, so that the peeling over time cannot be satisfied.

In the table, BA: butyl acrylate, AA: acrylic acid, AAEM: acetoacetoxyethyl methacrylate, KBM503: 3-methacryloyloxypropyl-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503), PAM200: mono [Poly (propylene oxide) methacrylate] Phosphate ester (manufactured by Rhodia Nikka Co., Ltd .: trade name “SipomerPAM-200”), DAAM: diacetone acrylamide.
Regarding the crosslinking agent, * 1: adipic acid dihydrazide (ADH, manufactured by Nippon Kasei Chemical Co., Ltd.), * 2: semicarbazide compound (Hardener SC, manufactured by Asahi Kasei Chemical Co., Ltd.) is shown. The compounding amount “0.2 ^* ” of the crosslinking agent of Comparative Example 1 means that the same compounding amount (0.16 parts) as that of Example 1 was blended.

Claims (9)

(Meth) acrylic acid alkyl ester (a) and a reversible monomer (b) having a functional group (x1) capable of causing a reversible reaction related to dehydration and hydrolysis reactions are contained as monomer units (meta ) Aqueous dispersion of acrylic copolymer (A),
The ratio of the (meth) acrylic acid alkyl ester (a) is 67 to 99.9% by weight of the total monomer units of the (meth) acrylic copolymer (A),
An aqueous dispersion of (meth) acrylic copolymer (A) in which the ratio of reversible monomer (b) is 0.1 to 10% by weight of the total monomer units of (meth) acrylic copolymer (A). ,
And a cross-linking agent (B) having at least two functional groups (x2) in the molecule that cause a reversible reaction related to dehydration and hydrolysis with respect to the functional group (x1) of the reversible monomer (b). contain,
The reversible monomer (b) is an aldehyde group-containing monomer or a keto group-containing monomer, wherein the functional group cross-linking agent has (x2) is, the optical film water-dispersible pressure-sensitive adhesive, wherein hydrazino group Der Rukoto Composition (however, rosin-based tackifying resin is not included). In addition to the (meth) acrylic acid alkyl ester (a) and the reversible monomer (b), the (meth) acrylic copolymer (A) has a carboxyl group-containing monomer as a copolymerization monomer. and it contained, and the proportion of the carboxyl group-containing monomer, according to claim 1, characterized in that it contains 0.1 to 10% by weight of the total monomer units of (meth) acrylic copolymer (a) A water-dispersed pressure-sensitive adhesive composition for optical films. The (meth) acrylic copolymer (A) contains an alkoxysilyl group-containing monomer (c) as a monomer unit, and the proportion of the alkoxysilyl group-containing monomer is a (meth) acrylic copolymer. The water-dispersed pressure-sensitive adhesive composition for optical films according to claim 1 or 2 , wherein the content is 0.001-1% by weight of the total monomer units of the polymer (A). The (meth) acrylic copolymer (A) contains a phosphate group-containing monomer as a monomer unit, and the proportion of the phosphate group-containing monomer is (meth) acrylic copolymer (A). The water-dispersed pressure-sensitive adhesive composition for optical films according to any one of claims 1 to 3 , wherein the content is 0.1 to 20% by weight of the total monomer units. An optical film pressure-sensitive adhesive layer formed by applying the water-dispersed pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 4 , followed by drying. The pressure-sensitive adhesive layer is
60 ° C., 7% R.F. H. Elongation at (L60) is 250% or less,
60 ° C., 7% R.F. H. Elongation at room temperature (L60) and 60 ° C., 90% R.V. H. The ratio {(L60-90) / (L60)} to the elongation (L60-90) at 1.5 is 1.5 or more.
However, the elongation rate was determined by forming the pressure-sensitive adhesive layer into a cylindrical test piece having a cross-sectional area of 4.6 mm ² and a length of 30 mm, and subjecting the test piece to 60 ° C., 7% R.D. H. Or 60 ° C., 90% R.D. H. The length L0 (mm) after being left for 1 hour in the environment of, and then, one end of the test piece was fixed, a 12 g weight was attached to the other end of the test piece, and the test piece was 60 ° C., 7% R. H. Or 60 ° C., 90% R.D. H. From the length L1 (mm) of the test piece after being dropped for 2 hours in the environment of
Elongation rate (%) = {(L1-L0) / L0} × 100,
The pressure-sensitive adhesive layer for an optical film according to claim 5 . The pressure-sensitive adhesive layer according to claim 5 or 6 , wherein the pressure-sensitive adhesive layer has a haze value (H20) of 0 to 1% when the thickness of the pressure-sensitive adhesive layer is 20 µm. An adhesive optical film, wherein the optical film pressure-sensitive adhesive layer according to any one of claims 5 to 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 .