JP6024271B2 - Acrylic film for protecting polarizer, polarizing plate, and liquid crystal display device - Google Patents

Description

  The present invention relates to an acrylic film for protecting a polarizer used for protecting a polarizer. In particular, the present invention relates to an acrylic film for protecting a polarizer excellent in adhesiveness with a polarizer.

  In the liquid crystal display device, polarizing plates are arranged on both sides of a glass substrate that forms the surface of the liquid crystal panel due to the image forming method. The polarizing plate generally has a configuration in which a polarizer protective film is bonded to both surfaces of a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine via a hydrophilic adhesive such as a polyvinyl alcohol resin. have. As a protective film used for protecting a polarizer, a triacetyl cellulose film has been conventionally used from the viewpoint of optical properties and transparency.

  However, triacetyl cellulose is not sufficiently durable, and when a polarizing plate using a triacetyl cellulose film as a polarizer protective film is used at high temperature or high humidity, the performance of the polarizing plate such as the degree of polarization and hue deteriorates. There is a case. In recent years, there has been a demand for thinning the polarizing plate in order to cope with the thinning of the display. However, from the viewpoint of maintaining moisture barrier properties, there has been a limit to thinning the triacetyl cellulose film.

  In a liquid crystal display device, an acrylic resin film is known as a resin film having excellent optical characteristics, and it has been proposed to use it as a polarizer protective film (Patent Documents 1 to 4).

The triacetyl cellulose film used as a polarizer protective film is subjected to alkali treatment or the like on its surface, and has an extremely high affinity with a hydrophilic adhesive. Therefore, the protective film made of a triacetyl cellulose film has extremely high adhesiveness with a polarizer coated with a hydrophilic adhesive.
However, the acrylic film is inferior in adhesiveness with the hydrophilic adhesive as compared with the triacetylcellulose film, and the adhesiveness with the polarizer is not sufficient. Therefore, when a polarizing plate using an acrylic film as a polarizer protective film is used as a display substrate for a long period of time, floating or peeling occurs between the polarizer protective film / polarizer and the moisture content in the polarizer changes. The polarization characteristics deteriorated and the visibility such as white spots sometimes deteriorated.

JP 2006-317560 A JP2008-9378 JP2007-254703 JP2010-240986

Under such circumstances, an object of the present invention is to protect a polarizer having means for firmly bonding an acrylic film and a polarizer or a polyvinyl alcohol resin layer such as an adhesive applied on the polarizer. It is to provide an acrylic film for use.

The inventors of the present invention have made extensive studies and studies to solve the above problems, and have a polyvinyl alcohol resin and a crosslinking agent having a high affinity between a polyester resin and a polyvinyl alcohol resin layer having a high affinity with an acrylic film. It came to the concept of providing a layer containing bismuth between the acrylic film and the polyvinyl alcohol resin layer. However, the present inventors have found that the function of bringing the acrylic film and the polyvinyl alcohol-based resin layer into contact with each other cannot be exhibited sufficiently by simply combining these components. Therefore, as a result of repeated researches day and night, the present inventors adopted a polyester resin having a certain acid value as the polyester resin in the above concept, and further, polyvinyl alcohol having a certain degree of saponification as the polyvinyl alcohol resin. It has been found that by using a system resin, it is possible to effectively exert the adhesive action of each component with a resin layer having high affinity.
As a result of further research based on the above findings, the present inventors have adopted a cross-linking agent having high reactivity with a hydroxyl group, so that an acrylic film and a polyvinyl alcohol resin such as a polarizer or an adhesive can be used. It has been found that it is possible to bond the layers more firmly. Based on these findings, the present inventors have made further studies and considerations, and have invented the present invention.

Below, the typical example of this invention is shown.
Item 1.
An acrylic film for protecting a polarizer having an easy adhesion layer with a polarizer, wherein the easy adhesion layer contains a polyester resin (A), a polyvinyl alcohol resin (B), and a crosslinking agent (C), The crosslinking agent (C) is an isocyanate compound or a melamine compound, the acid value of the polyester resin (A) is 20 KOHmg / g or less, and the saponification degree of the polyvinyl alcohol resin (B) is 60 to 85 mol%. der is, the easy adhesion layer, the polarizer protective acrylic, wherein the weight ratio of the polyester resin (a), the polyvinyl alcohol-based resin (B) and crosslinking agent (C) satisfies the following equation Film.
0.8 ≦ (A) / (B) ≦ 5
10 ≦ ((A) + (B)) / (C) ≦ 30
Item 2.
Item 2. The polarizer-protecting acrylic film according to Item 1, wherein the polyester- based resin (A) contains 1 to 15 mol% of a 5-sulfoisophthalic acid component in the dicarboxylic acid component.
Item 3 .
The polarizing plate which has a polarizer protective film on both surfaces of a polarizer, Comprising: At least one polarizer protective film is an acrylic film for polarizer protection of claim | item 1 or 2 .
Item 4 .
A polarizing plate having a polarizer protective film on both sides of a polarizer, wherein at least one of the polarizer protective films is an acrylic film for protecting a polarizer according to Item 1 or 2 , and the other polarizer protective film is A polarizing plate, which is an oriented polyester film having a retardation of 3000 to 30000 nm.
Item 5 .
Item 5. A liquid crystal display device comprising the polarizing plate according to item 3 or 4 .

  The acrylic film for protecting a polarizer of the present invention is excellent in adhesion with a polarizer or a polyvinyl alcohol-based resin layer represented by an adhesive applied thereon. Therefore, the acrylic film of the present invention can be suitably used as a protective film for a polarizer. By using such an acrylic film of the present invention as a protective film for a polarizer, it is possible to produce a polarizing plate having superior durability and water barrier properties at a lower cost than before. Moreover, since the polarizing plate of the present invention is excellent in durability, it can be made thinner than before. Therefore, it is possible to further reduce the thickness of the liquid crystal display by using the polarizing plate of the present invention.

(Acrylic film)
In the present application, the acrylic resin is a general term for a polymer obtained by using an acrylic monomer as a main raw material, and a resin obtained by modifying and / or reacting them.

  The acrylic film of the present invention can be obtained by forming a known acrylic resin into a film by a known method. A film having a small retardation expressed by the product of birefringence and thickness is preferred.

  Known materials can be used for the acrylic resin. Although not particularly limited, a lactone resin, a glutaric anhydride resin, a glutarimide resin, or the like can be preferably used. The lactone resin is not particularly limited, but can be produced according to the method described in JP-A-2008-9378. Although it does not restrict | limit especially as glutaric anhydride resin, It can manufacture according to the method of Unexamined-Japanese-Patent No. 2007-254703, etc.

  The thickness of the acrylic film according to the present invention is not particularly limited, but is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm, and further preferably 30 μm to 100 μm.

  When the thickness of the film is within the above range, an optical film having uniform optical characteristics and good haze can be obtained.

  On the other hand, if the thickness of the film exceeds the above range, the cooling of the film becomes non-uniform and the optical characteristics tend to be non-uniform. Moreover, when the thickness of the film is less than the above range, the draw ratio becomes excessive, and the haze tends to deteriorate.

  The acrylic film preferably has a small optical anisotropy. More specifically, the in-plane retardation is preferably 10 nm or less, more preferably 6 nm or less, further preferably 5 nm or less, and particularly preferably less than 3 nm. In particular, it is preferable that not only the optical anisotropy in the in-plane direction (length direction, width direction) of the film but also the optical anisotropy in the thickness direction is small. In other words, it is preferable that both the in-plane retardation and the thickness direction retardation are small.

  On the other hand, when a polarizer protective film having a large in-plane retardation of the film is used as a polarizing plate of a liquid crystal display device, a problem such as a decrease in contrast may occur in the liquid crystal display device.

The acrylic film for protecting a polarizer may be subjected to a surface treatment. The surface treatment is not particularly limited, and examples thereof include corona treatment, plasma treatment, ultraviolet irradiation, and alkali treatment. Among these, corona treatment is preferable.

(Easily adhesive layer)
The acrylic film of the present invention has an acid value of 20 KOHmg / g or less on at least one surface thereof in order to improve adhesion between the polarizer and a polyvinyl alcohol resin layer such as a water-based adhesive provided on one or both surfaces of the polarizer. A polyester resin (A), a polyvinyl alcohol resin (B) having a saponification degree of 60 to 85 mol%, and an easy adhesion layer formed from a resin composition containing a crosslinking agent (C) are laminated. ing. The easy adhesion layer may be provided on both sides of the acrylic film, may be provided only on one side of the acrylic film, and a different type of resin coating layer may be provided on the other side.

Although not limited by theory, it is crosslinked with a specific polyester resin (A) having an acid value of 20 KOHmg / g or less and a specific polyvinyl alcohol resin (B) having a saponification degree of 60 to 85 mol%. By combining the agent (C), it is considered that the polyester-based resin and the polyvinyl alcohol-based resin form separate domain units in the easy-adhesion layer, and form a phase separation structure generally called a sea-island structure. By taking such a domain unit separation structure, the adhesiveness with the acrylic film by the domain constituted by the polyester resin and the adhesiveness with the polyvinyl alcohol resin layer by the domain constituted by the polyvinyl alcohol resin. It is considered that the two functions are preferably compatible with each other without being impaired. The crosslinking agent (C) is considered to promote and maintain the formation of the domain structure by crosslinking and aggregating the polyvinyl alcohol resin (B).
Hereinafter, each composition of an easily bonding layer is explained in full detail.

(Polyester resin (A))
The polyester-based resin (A) used in the easy-adhesion layer of the present invention is a copolymer obtained by polycondensation of a dicarboxylic acid component and a diol component, and the above-described materials can be used as the dicarboxylic acid component and the diol component. it can.

Examples of the dicarboxylic acid component of the polyester resin (A) include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracene dicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, Hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipine Acid, pime Phosphate, azelaic acid, dimer acid, sebacic acid, suberic acid, dodecamethylene dicarboxylic acid and the like.

Moreover, as a glycol component of a polyester-type resin (A), it is preferable to make ethylene glycol and the branched glycol into a structural component. By having a branched structure, it is considered that it contributes to stress relaxation in the easy-adhesion layer, and it is possible to suitably exhibit adhesion. Examples of the branched glycol component include 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, and 2-methyl-2-butyl-1,3. -Propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-methyl-2-n-hexyl-1,3-propanediol 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl-2-n-hexyl-1,3-propanediol, 2, Such as 2-di-n-butyl-1,3-propanediol, 2-n-butyl-2-propyl-1,3-propanediol, and 2,2-di-n-hexyl-1,3-propanediol. And the like.

  The molar ratio of the branched glycol component is preferably 10 mol%, particularly preferably 20 mol%, based on the total glycol component. On the other hand, the upper limit is preferably 80 mol%, more preferably 70 mol%, and particularly preferably 60 mol%. If necessary, diethylene glycol, propylene glycol, butanediol, hexanediol, 1,4-cyclohexanedimethanol or the like may be used in combination.

  The polyester resin (A) used in the present invention is preferably a water-soluble or water-dispersible resin from the viewpoint of compatibility with the polyvinyl alcohol resin (B). In order to make the polyester resin water-soluble or water-dispersed, it is preferable to copolymerize a compound containing a hydrophilic group such as a sulfonate group or a carboxylate group. Among these, a dicarboxylic acid component having a sulfonate group is preferable from the viewpoint of imparting hydrophilicity while keeping the acid value of the polyester-based resin (A) low and controlling the reactivity with the crosslinking agent. Examples of the dicarboxylic acid component having a sulfonate group include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfonaphthaleneisophthalic acid-2,7-dicarboxylic acid, and 5- (4-sulfophenoxy) isophthalic acid or an alkali thereof. Examples of the metal salt include 5-sulfoisophthalic acid. 1-15 mol% is preferable in the dicarboxylic acid component of a polyester resin (A), the dicarboxylic acid component which has a sulfonate group has more preferable 1.5-12 mol%, and 2-10 mol% is further more preferable. When the dicarboxylic acid component having a sulfonate group is at least the above lower limit, it is suitable for water-solubilization or water-dispersion of the polyester resin. Moreover, when the dicarboxylic acid component which has a sulfonate group is below the said upper limit, it is suitable for adhesiveness with an acrylic film base material.

  The polyester resin (A) preferably has fewer carboxylic acid groups which are reactive groups with the crosslinking agent (C). By reducing the number of carboxyl groups that are reactive with the cross-linking agent, the reactivity with the cross-linking agent is reduced. As a result, the cross-linking polyvinyl alcohol-based resin does not completely mix with the polyvinyl alcohol-based resin. It is considered possible to maintain the domain structure that is formed. From such a viewpoint, the acid value of the polyester resin (A) is 20 KOHmg / g or less, preferably 15 KOHmg / g or less, more preferably 10 KOHmg / g or less, further preferably 8 KOHmg / g or less, and still more preferably 5 KOHmg. / G or less. The acid value of the polyester resin (A) can be theoretically determined from the result of component analysis by titration method described later or NMR.

  In order to control the acid value of the polyester resin (A) within the above range, the introduction amount of the carboxylic acid base for water solubilization or water dispersion is reduced, or hydrophilic groups other than the carboxylic acid base are employed. Or lowering the carboxylic acid terminal concentration of the polyester resin. As a method for lowering the carboxylic acid terminal concentration of the polyester resin, it is preferable to employ a polyester resin in which the carboxylic acid terminal group is modified, or a polyester resin having a large number average molecular weight of the polyester resin. For this reason, the number average molecular weight of the polyester resin (A) is preferably 5000 or more, more preferably 6000 or more, and further preferably 10,000 or more. Moreover, it is preferable to make low content of the acid component which has a polyester-type resin (A) as a structural component and has three or more carboxyl groups.

  Although the glass transition temperature of a polyester-type resin (A) is not specifically limited, It is preferable that it is 20-90 degreeC, and it is more preferable that it is 30-80 degreeC. When the glass transition temperature is not less than the above lower limit, it is suitable for blocking resistance, and when the glass transition temperature is not more than the above upper limit, it is suitable for adhesiveness with an acrylic film substrate.

  40 mass% or more and 90 mass% or less are preferable, as for content of the polyester-type resin (A) in an easily bonding layer, 45 mass% or more and 85 mass% or less are more preferable, and 50 mass% or more and 80 mass% or less are more preferable. . When the content of the polyester resin (A) is not less than the above lower limit, it is suitable for adhesion to an acrylic film substrate, and when it is not more than the above upper limit, it is suitable for adhesion to a polarizer / water-based resin.

(Polyvinyl alcohol resin (B))
The polyvinyl alcohol-based resin is not particularly limited. For example, polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; and a saponified product of a copolymer of vinyl acetate and a monomer having copolymerizability; And modified polyvinyl alcohol obtained by converting polyvinyl alcohol into acetalized, urethanized, etherified, grafted, phosphoric acid ester or the like. Examples of the monomer include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and esters thereof; α-olefins such as ethylene and propylene, (meth) Examples include allyl sulfonic acid (soda), sulfonic acid soda (monoalkyl malate), disulfonic acid soda alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinyl pyrrolidone, N-vinyl pyrrolidone derivatives, and the like. . These polyvinyl alcohol resins may be used alone or in combination of two or more.

  Examples of the polyvinyl alcohol resin (B) used in the present invention include vinyl alcohol-vinyl acetate copolymer, vinyl alcohol-vinyl butyral copolymer, and ethylene-vinyl alcohol copolymer. Among these, vinyl alcohol-vinyl acetate A copolymer and an ethylene-vinyl alcohol copolymer are preferred. The polymerization degree of the polyvinyl alcohol-based resin (B) is not particularly limited, but the polymerization degree is preferably 3000 or less from the viewpoint of the coating solution viscosity.

  The copolymerization ratio of vinyl alcohol is represented by the degree of saponification. The saponification degree of the polyvinyl alcohol resin (B) of the present invention is preferably 60 mol% or more and 85 mol% or less, more preferably 65 mol% or more and 83 mol% or less, further preferably 68 mol% or more and 80 mol% or less, and 70 More preferably, it is more than mol% and less than 80 mol%, still more preferably 71 mol% or more and 78 mol% or less, and particularly preferably 73 mol% or more and 75 mol% or less. When the degree of saponification of the polyvinyl alcohol resin (B) is not less than the above lower limit, a crosslinked structure can be more suitably formed with the crosslinking agent (C). Further, when the degree of saponification of the polyvinyl alcohol-based resin (B) is not more than the above upper limit (or less), compatibility with the polyester-based resin (A) can be more suitably achieved. The degree of saponification of the vinyl alcohol-based resin can be determined by the amount of alkali consumption required for hydrolysis of copolymer units such as vinyl acetate or the composition analysis by NMR.

  The content of the polyvinyl alcohol resin (B) is preferably 10% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 55% by mass or less, and more preferably 20% by mass or more and 50% by mass or less in the easy-adhesion layer. Further preferred. When the content of the polyvinyl alcohol resin (B) is not less than the above lower limit, it is suitable for adhesiveness with a polarizer / water-based resin, and when it is not more than the above upper limit, it is suitable for adhesiveness with an acrylic film substrate. .

(Crosslinking agent (C))
The crosslinking agent (C) is not particularly limited as long as it has crosslinkability with a hydroxyl group, and examples thereof include melamine-based, isocyanate-based, carbodiimide-based, oxazoline-based, and epoxy-based compounds. Melamine-based, isocyanate-based, carbodiimide-based, and oxazoline-based compounds are preferable from the viewpoint of the temporal stability of the coating solution. Furthermore, the crosslinking agent is preferably a melamine compound or an isocyanate compound that suitably cross-links with the hydroxyl group of the polyvinyl alcohol resin (B). This is because a carbodiimide-based cross-linking agent reacts with a carboxyl group, whereas a melamine-based compound or an isocyanate-based compound reacts with a hydroxyl group, and therefore, a polyvinyl alcohol resin (B) having a hydroxyl group as a functional group is more preferably a crosslinked structure. This is thought to be because of Especially, it is especially preferable to use an isocyanate type compound from a viewpoint that it forms a crosslinking reaction suitably with the hydroxyl group of polyvinyl alcohol-type resin, and is excellent in transparency. Moreover, in order to promote a crosslinking reaction, you may use a catalyst etc. suitably as needed.

  As the isocyanate compound, a low-molecular or high-molecular diisocyanate or a trivalent or higher polyisocyanate can be used. For example, as the isocyanate compound, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 1,5 -Naphthylene diisocyanate, 1,4-naphthylene diisocyanate, phenylene diisocyanate, tetramethylxylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane 4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, 3,3'-dimethoxydiph Aromatic diisocyanates such as nyl-4,4'-diisocyanate, aromatic aliphatic diisocyanates such as xylylene diisocyanate, isophorone diisocyanate and 4,4-dicyclohexylmethane diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, etc. Examples thereof include aliphatic diisocyanates such as alicyclic diisocyanates, hexamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate, and trimers of these isocyanate compounds. Furthermore, an excess amount of these isocyanate compounds and low molecular active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, or polyester polyols, poly Mention may be made of a polymer containing a terminal isocyanate group of a polymer obtained by reacting a polymer active hydrogen compound such as ether polyols and polyamides.

  As the crosslinking agent (C) used in the present invention, a blocked isocyanate compound is also preferable. By adding the blocked isocyanate compound, it is possible to more suitably improve the temporal stability of the coating solution.

  The blocked isocyanate compound can be prepared by subjecting the isocyanate compound and the blocking agent to an addition reaction by a conventionally known method. Examples of the isocyanate blocking agent include phenols such as phenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol; thiophenols such as thiophenol and methylthiophenol; oximes such as acetoxime, methyl etiketooxime, and cyclohexanone oxime. Compounds; pyrazole compounds such as 3,5-dimethylpyrazole, 3-methylpyrazole, 4-bromo-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole; alcohols such as methanol, ethanol, propanol and butanol Halogen substituted alcohols such as ethylene chlorohydrin and 1,3-dichloro-2-propanol; tertiary alcohols such as t-butanol and t-pentanol; ε- Lactams such as prolactam, δ-valerolactam, γ-butyrolactam, β-propyllactam; aromatic amines; imides; acetylacetone, acetoacetate, malonic acid ethyl ester, malonic acid diester (dimethyl malonate, malonic acid Active methylene compounds such as diethyl, di-n-butyl malonate, di-2-ethylhexyl malonate); triazole compounds such as 1,2,4-triazole; mercaptans; imines; ureas; diaryl compounds; sodium bisulfite; And so on.

  As content of a crosslinking agent (C), 2 to 50 mass% is preferable in an easily bonding layer, 5 to 40 mass% is more preferable, 8 to 30 mass% is further more preferable. . When the content of the crosslinking agent (C) is not less than the above lower limit, it is suitable for forming a crosslinked polyvinyl alcohol resin, and when it is not more than the above upper limit, it is suitable for expression of an adhesive effect by the binder resin.

  The blending ratio (A) / (B) of the polyester resin (A) and the polyvinyl alcohol resin (B) is preferably 0.8 to 5, more preferably 1 to 4, more preferably 2 More preferably, it is-4, and it is especially preferable that it is 2.5-3.5. When (A) / (B) is not less than the above lower limit, it is suitable for adhesion to an acrylic film substrate, and when it is not more than the above upper limit, it is suitable for adhesion to a polarizer / water-based resin.

  The blending ratio ((A) + (B)) / (C) of the polyester resin (A) and the polyvinyl alcohol resin (B) and the crosslinking agent (C) is preferably 2 to 50 in terms of mass ratio. More preferably, it is -40, and it is further more preferable that it is 8-30. When ((A) + (B)) / (C) is not less than the above lower limit, it is suitable for expression of the adhesive effect by the binder resin component, and when it is not more than the above upper limit, it is suitable for the adhesive effect by phase separation. .

  By adopting the above composition, the easy-adhesion layer of the present invention exhibits high adhesiveness equivalent to that of triacetyl cellulose to polarizers and aqueous adhesives, particularly polyvinyl alcohol-based polarizers and aqueous adhesives. Specifically, the remaining area after peeling once is preferably 90% or more, more preferably 95% or more, and further preferably 100% with respect to the water-based adhesive according to the adhesive test described later. The remaining area after is preferably 75% or more, more preferably 85% or more, further preferably 95% or more, and the remaining area after 10 continuous peelings is preferably 50% or more, more preferably 80% or more, Preferably it is 90% or more, More preferably, it is 93% or more, Most preferably, it is 95% or more.

(Additive)
In the easy-adhesion layer of the present invention, known additives such as surfactants, antioxidants, catalysts, heat stabilizers, weathering stabilizers, UV absorbers, organic absorbers, and the like within a range that does not inhibit the effects of the present invention. Lubricants, pigments, dyes, organic or inorganic particles, antistatic agents, nucleating agents, and the like may be added.

  In this invention, in order to improve the blocking resistance of an easily bonding layer, it is also a preferable aspect to add particle | grains to an easily bonding layer. Examples of the particles contained in the easy-adhesion layer in the present invention include titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay and the like, or a mixture thereof. Inorganic particles such as calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, calcium fluoride and other inorganic particles, styrene-based, acrylic-based, melamine-based, benzoguanamine-based, silicone-based Examples include organic polymer particles.

  The average particle diameter of the particles in the easy-adhesion layer (number average particle diameter by SEM; the same applies hereinafter) is preferably 0.04 to 2.0 μm, more preferably 0.1 to 1.0 μm. If the average particle size of the inert particles is less than 0.04 μm, the formation of irregularities on the film surface becomes insufficient, so that the handling properties such as the slipping property and the winding property of the film are deteriorated and the film is stuck. The workability at the time of alignment may deteriorate. On the other hand, if it exceeds 2.0 μm, the particles are likely to fall off, which is not preferable. The particle concentration in the easy-adhesion layer is preferably 1 to 20% by mass and more preferably 5 to 15% by mass in the solid component.

In the present invention, the thickness of the easy-adhesion layer can be appropriately set in the range of 0.001 to 2.00 g / m ² , but 0.01 to 1.00 g for achieving both workability and adhesiveness. / M ² is preferable, more preferably 0.02 to 0.80 g / m ² , and still more preferably 0.05 to 0.50 g / m ² . Adhesiveness will become inadequate that the thickness of an easily bonding layer is less than 0.01 g / m < ² >. If the thickness of the easy adhesion layer exceeds 1.00 g / m ² , blocking may occur.

(Manufacture of acrylic film for polarizer protection)
A method for producing a film containing an acrylic resin according to the present invention will be described, but the present invention is not limited to this. That is, any conventionally known method can be used as long as it is a method capable of producing a film by molding the acrylic resin according to the present invention.

  Specific examples include injection molding, melt-extruded film molding, inflation molding, blow molding, compression molding, and the like.

  The film according to the present invention can also be produced by a solution casting method or a spin coating method in which the acrylic resin according to the present invention is dissolved in a soluble solvent and then molded.

  Among them, it is preferable to use a melt extrusion method that does not use a solvent. According to the melt extrusion method, it is possible to reduce the burden on the global environment and the working environment due to manufacturing costs and solvents.

  Hereinafter, as an embodiment of a method for producing a film according to the present invention, a method for producing a film by molding the acrylic resin according to the present invention by a melt extrusion method will be described in detail.

  When the acrylic resin according to the present invention is formed into a film by a melt extrusion method, first, the acrylic resin according to the present invention is supplied to an extruder, and the acrylic resin is heated and melted.

  Next, the acrylic resin heated and melted in the extruder is supplied to the T die through a gear pump and a filter. At this time, if a gear pump is used, the uniformity of the extrusion amount of the resin can be improved and thickness unevenness can be reduced. On the other hand, if a filter is used, the foreign material in acrylic resin can be removed and the film excellent in the external appearance without a defect can be obtained.

  Next, the acrylic resin supplied to the T die is extruded from the T die as a sheet-like molten resin. Then, the sheet-like molten resin is sandwiched between two cooling rolls and cooled to form a film.

  The method for stretching the film is not particularly limited, and any conventionally known stretching method may be used. Specifically, for example, sequential biaxial stretching in which these are sequentially combined, such as longitudinal stretching using a roll and transverse stretching using a tenter, can be used. Simultaneous biaxial stretching in which transverse stretching and longitudinal stretching are simultaneously performed is also a suitable method.

  The easy adhesion layer can be provided after the production of the film or in the production process. In particular, from the viewpoint of productivity, it is preferable to apply an application liquid to at least one side of an acrylic film after being stretched or uniaxially stretched in any stage of the film production process to form an easy adhesion layer.

  Any known method can be used as a method for applying the coating solution for the easy adhesion layer to the acrylic film. For example, reverse roll coating method, gravure coating method, kiss coating method, die coater method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, impregnation coating method, curtain coating method, etc. It is done. These methods are applied alone or in combination.

In this invention, it is preferable that the thickness of the easily bonding layer finally obtained is 0.01-1.00 g / m < ² >. If it is less than 0.01 g / m < ² >, adhesiveness will fall, and if it is thicker than 1.00 g / m < ² >, since blocking property and slipperiness will fall, it is not preferable.

(Polarizer)
The polarizing plate of the present invention is a polarizing plate having a polarizer protective film on both sides of the polarizer, and at least one of the polarizer protective films is preferably the above-mentioned acrylic film for protecting a polarizer. . The other polarizer protective film may be an easily adhesive acrylic film for protecting a polarizer of the present invention, or a film having no birefringence such as a triacetyl cellulose film or a norbornene film may be used. Is also preferable.
Moreover, it is also a preferable aspect to use the oriented polyester film which has a retardation of 3000-30000 nm for the other polarizer protective film. Such a polarizing plate and a liquid crystal display device using a white LED as a backlight light source can suppress the occurrence of rainbow spots and can reduce the thickness of the liquid crystal display device.

  Examples of the polarizer include a polyvinyl alcohol film containing a dichroic material such as iodine. The polarizer protective film is bonded to the polarizer directly or via an adhesive layer, but it is preferable to bond the polarizer protective film via an adhesive from the viewpoint of improving adhesiveness. In that case, it is preferable to arrange | position the easily bonding layer of this invention to a polarizer surface or an adhesive bond layer surface. As a preferred polarizer for adhering the acrylic film of the present invention, for example, iodine or dichroic material is dyed and adsorbed on a polyvinyl alcohol film, uniaxially stretched in a boric acid aqueous solution, and the stretched state is maintained. Examples thereof include a polarizer obtained by washing and drying as it is. The draw ratio of uniaxial stretching is usually about 4 to 8 times. Polyvinyl alcohol is suitable as the polyvinyl alcohol film. “Kuraray Vinylon” [manufactured by Kuraray Co., Ltd.], “Tosero Vinylon” [manufactured by Tosero Co., Ltd.], “Nichigo Vinylon” [Nippon Synthetic Chemical Co., Ltd.] Commercial products such as “made” can be used. Examples of the dichroic material include iodine, a disazo compound, and a polymethine dye.

  From the viewpoint of thinning the adhesive layer, the adhesive applied to the polarizer is preferably an aqueous one, that is, an adhesive component dissolved in water or dispersed in water. For example, a polyvinyl alcohol resin, a urethane resin, or the like is used as a main component, and a composition containing an isocyanate compound, an epoxy compound, or the like can be used as necessary in order to improve adhesiveness. The thickness of the adhesive layer is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less.

  When using polyvinyl alcohol resin as the main component of the adhesive, in addition to partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, amino group-modified A modified polyvinyl alcohol resin such as polyvinyl alcohol may be used. 1-10 mass% is preferable and, as for the density | concentration of the polyvinyl alcohol-type resin in an adhesive agent, 2-7 mass% is more preferable.

Next, the present invention will be described in detail using examples, comparative examples, and reference examples, but the present invention is not limited to the following examples. Hereinafter, Example 12 will be read as Reference Example 12. The evaluation method used in the present invention is as follows.

(1) Glass transition temperature In accordance with JIS K7121, using a differential scanning calorimeter (Seiko Instruments, DSC6200), 10 mg of a resin sample was heated at a rate of 20 ° C / min over a temperature range of 25 to 300 ° C, and DSC The extrapolated glass transition start temperature obtained from the curve was defined as the glass transition temperature.

(2) Number average molecular weight 0.03 g of resin was dissolved in 10 ml of tetrahydrofuran, and GPC-LALLS apparatus low-angle light scattering photometer LS-8000 (manufactured by Tosoh Corporation, tetrahydrofuran solvent, reference: polystyrene) was used. The number average molecular weight was measured using a flow rate of 1 ml / min and a column (showex KF-802, 804, 806 manufactured by Showa Denko KK).

(3) Resin composition The resin is dissolved in deuterated chloroform, 1H-NMR analysis is performed using a nuclear magnetic resonance analyzer (NMR) Gemini-200 manufactured by Varian, and the mol% ratio of each composition is determined from the integration ratio. did.

(4) Acid value 1 g (solid content) of a sample was dissolved in 30 ml of chloroform or dimethylformamide, and titrated with 0.1 N potassium hydroxide ethanol solution using phenolphthalein as an indicator to determine the carboxyl groups per gram of the sample. The amount (mg) of KOH required for neutralization was determined.

(5) Saponification degree Residual acetate groups (mol%) of the polyvinyl alcohol resin were quantified using sodium hydroxide according to JIS-K6726, and the value was defined as the saponification degree (mol%). The sample was measured three times, and the average value was defined as the saponification degree (mol%).

(6) PVA adhesiveness The thickness of the polyvinyl alcohol resin layer after drying a polyvinyl alcohol aqueous solution (Pura117 made by Kuraray) adjusted to a solid content concentration of 5% by mass on the surface of the easily adhesive layer of the acrylic film for protecting a polarizer, It apply | coated with the wire bar so that it might become 2 micrometers, and it dried for 5 minutes at 70 degreeC. As the polyvinyl alcohol aqueous solution, a solution in which a red dye was added so as to facilitate the determination was used. The prepared evaluation target film was attached to a glass plate having a thickness of 5 mm to which a double-sided tape was attached, and the opposite surface of the evaluation target laminated film on which the polyvinyl alcohol resin layer was formed was attached to the double-sided tape. Next, 100 grid-like cuts that penetrated through the polyvinyl alcohol resin layer and reached the base film were made using a cutter guide with a gap interval of 2 mm. Next, an adhesive tape (Cello Tape (registered trademark) CT-24; 24 mm width, manufactured by Nichiban Co., Ltd.) was attached to the grid-shaped cut surface. The air remaining at the interface at the time of pasting was pressed with an eraser to bring it into close contact, and then the work of peeling off the adhesive tape vigorously vertically was performed once, five times and ten times. The number of squares on which the polyvinyl alcohol resin layer was not peeled was counted to determine PVA adhesion. That is, when the PVA layer was not peeled off at all, the PVA adhesion rate was 100, and when all the PVA layer was peeled off, the PVA adhesion rate was 0. In addition, what was partially peeled within one square was also included in the number of peeled.

(Polyester resin polymerization)
In a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux condenser, 194.2 parts by weight of dimethyl terephthalate, 184.5 parts by weight of dimethyl isophthalate, 14.8 parts by weight of dimethyl-5-sodium sulfoisophthalate, The mixture was charged with 233.5 parts by mass of diethylene glycol, 136.6 parts by mass of ethylene glycol, and 0.2 parts by mass of tetra-n-butyl titanate, and subjected to a transesterification reaction at a temperature of 160 to 220 ° C. over 4 hours. Next, the temperature was raised to 255 ° C., and the pressure of the reaction system was gradually reduced, followed by reaction for 1 hour 30 minutes under a reduced pressure of 30 Pa to obtain a copolymerized polyester resin (A-1). The obtained copolyester resin (A-1) was light yellow and transparent. It was 0.70 dl / g when the reduced viscosity of copolyester resin (A-1) was measured. The glass transition temperature by DSC was 40 ° C.

  In the same manner, copolymer polyester resins (A-2) to (A-5) having different compositions were obtained. Table 1 shows the composition (mole% ratio) and other characteristics measured by 1H-NMR for these copolymer polyester resins.

(Adjustment of polyester aqueous dispersion)
30 parts by mass of polyester resin (A-1) and 15 parts by mass of ethylene glycol n-butyl ether were placed in a reactor equipped with a stirrer, a thermometer and a reflux device, and heated and stirred at 110 ° C. to dissolve the resin. After the resin was completely dissolved, 55 parts by mass of water was gradually added to the polyester solution while stirring. After the addition, the solution was cooled to room temperature while stirring to prepare a milky white polyester aqueous dispersion (Aw-1) having a solid content of 30% by mass. Similarly, using the polyester resins (A-2) to (A-5) instead of the polyester resin (A-1), water dispersions are prepared, and the polyester water dispersions (Aw-2) to (Aw) are respectively produced. -5).

(Preparation of aqueous polyvinyl alcohol solution)
In a container equipped with a stirrer and a thermometer, 90 parts by mass of water was added, and 10 parts by mass of polyvinyl alcohol resin (manufactured by Kuraray) (B-1) having a polymerization degree of 500 was gradually added while stirring. After the addition, the solution was heated to 95 ° C. while stirring to dissolve the resin. After dissolution, the mixture was cooled to room temperature with stirring to prepare a polyvinyl alcohol aqueous solution (Bw-1) having a solid content of 10% by mass. Similarly, polyvinyl alcohol resins (B-2) to (B-7) were used instead of the polyvinyl alcohol resin (B-1) to prepare aqueous solutions, which were designated as (Bw-2) to (Bw-7), respectively. . Table 2 shows the degree of saponification of the polyvinyl alcohol resins (B-1) to (B-7).

(Polymerization of block polyisocyanate crosslinking agent)
In a flask equipped with a stirrer, thermometer and reflux condenser, 100 parts by mass of a polyisocyanate compound having an isocyanurate structure using hexamethylene diisocyanate as a raw material (manufactured by Asahi Kasei Chemicals, Duranate TPA), 55 parts by mass of propylene glycol monomethyl ether acetate, polyethylene 30 parts by mass of glycol monomethyl ether (average molecular weight 750) was charged, and kept at 70 ° C. for 4 hours under a nitrogen atmosphere. Thereafter, the reaction solution temperature was lowered to 50 ° C., and 47 parts by mass of methyl ethyl ketoxime was added dropwise. The infrared spectrum of the reaction solution was measured to confirm that the absorption of the isocyanate group had disappeared, and a block polyisocyanate aqueous dispersion (C-1) having a solid content of 75% by mass was obtained.

Example 1
(1) Adjustment of coating liquid The following coating agent was mixed and the coating liquid from which the mass ratio of polyester-type resin (A) / polyvinyl alcohol-type resin (B) became 70/30 was created. The polyester aqueous dispersion uses an aqueous dispersion (Aw-1) in which a polyester resin having an acid value of 2 KOH mg / g is dispersed, and the polyvinyl alcohol aqueous solution is an aqueous solution in which polyvinyl alcohol having a saponification degree of 74 mol% is dissolved. (Bw-4) was used.
Water 40.61 mass%
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 11.67 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 15.00 mass%
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

(2) Manufacture of acrylic film for protecting polarizer One part of TINUVIN 1577 (manufactured by Ciba Specialty Chemicals) and one part of ADK STAB LA-31 (manufactured by Asahi Denka Kogyo Co., Ltd.) per 100 parts of polymethyl methacrylate resin Resin A obtained by mixing resin B1 and resin B2 obtained only from polymethyl methacrylate resin into three extruders connected to a T-die, resin B1 on one side of resin A, Resin B2 is directly fed to the other side, melt-kneaded and then extruded from a T-die at a die temperature of 250 ° C. with a single-screw extruder so as to form three layers, and then cooled with water using a cooling roll. A film having a thickness of 40 μm (the thickness of each layer is resin A layer: 30 μm, resin B1 layer: 5 μm, resin B2 layer: 5 μm) was obtained.

The coating solution prepared above was applied to the film obtained above with a wire bar so that the coating amount after drying was 0.12 g / m ² and dried at 160 ° C. for 1 minute. The evaluation results of the acrylic film for protecting a polarizer having the easy-adhesion layer thus obtained are shown in Table 3.

Example 2
Acrylic film for protecting a polarizer in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer was changed to an aqueous dispersion (Aw-2) in which a polyester resin having an acid value of 4 KOHmg / g was dispersed. Got.

Example 3
An acrylic film for protecting a polarizer in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer was changed to an aqueous dispersion (Aw-3) in which a polyester resin having an acid value of 6 KOHmg / g was dispersed. Got.

Example 4
An acrylic film for protecting a polarizer was prepared in the same manner as in Example 1 except that the polyvinyl alcohol aqueous solution of the easy adhesion layer was changed to a polyvinyl alcohol aqueous solution (Bw-3) having a saponification degree of polyvinyl alcohol of 79 mol%. Obtained.

Example 5
A polarizer protective acrylic film was obtained in the same manner as in Example 1 except that the polyvinyl alcohol aqueous solution (Bw-2) having a saponification degree of polyvinyl alcohol of 83 mol% in the easy adhesion layer was changed.

Example 6
In the same manner as in Example 1 except that the easy-adhesion layer was mixed with the following coating agent and the mass ratio of polyester resin (A) / polyvinyl alcohol resin (B) was changed to 60/40. A child protecting acrylic film was obtained.
Water 37.28% by mass
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 10.00 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 20.00 mass%
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 7
In the same manner as in Example 1 except that the easy-adhesion layer was mixed with the following coating agent and the mass ratio of the polyester resin (A) / polyvinyl alcohol resin (B) was changed to 80/20. A child protecting acrylic film was obtained.
43.95% by weight of water
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 13.33 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 10.00 mass%
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 8
In the same manner as in Example 1, except that the easy-adhesion layer was mixed with the following coating agent and the mass ratio of the polyester resin (A) / polyvinyl alcohol resin (B) was changed to 50/50, the polarization was changed. A child protecting acrylic film was obtained.
Water 33.95% by mass
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 8.33 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 25.00% by mass
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 9
An acrylic film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution composition of the easy adhesion layer was changed as follows.
40.87% by mass of water
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 11.67 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 15.00 mass%
Melamine type crosslinking agent (C-2) 0.71 mass%
(Nikarak MX-042, manufactured by Sanwa Chemical Co., Ltd., solid content concentration 70%)
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 10
Acrylic for protecting a polarizer in the same manner as in Example 1, except that the polyvinyl alcohol aqueous solution of the easy adhesion layer was changed to an aqueous solution (Bw-5) in which polyvinyl alcohol having a saponification degree of polyvinyl alcohol of 70 mol% was dissolved. A system film was obtained.

Example 11
Acrylic for protecting a polarizer in the same manner as in Example 1, except that the polyvinyl alcohol aqueous solution of the easy adhesion layer was changed to an aqueous solution (Bw-6) in which polyvinyl alcohol having a saponification degree of polyvinyl alcohol of 67 mol% was dissolved. A system film was obtained.

Example 12
An acrylic film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution composition of the easy adhesion layer was changed as follows.
40.33% by mass of water
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 11.67 mass%
Polyvinyl alcohol aqueous solution (Bw-2) 15.00 mass%
Oxazoline-based crosslinking agent (C-3) 1.25% by mass
(Epocross WS-500, manufactured by Nippon Shokubai, solid concentration 40% by mass)
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 13
An acrylic film for protecting a polarizer in the same manner as in Example 1, except that the polyester aqueous dispersion of the easy-adhesion layer was changed to an aqueous dispersion (Aw-5) in which a polyester resin having an acid value of 10 KOHmg / g was dispersed. Got.

Comparative Example 1
Acrylic for protecting a polarizer in the same manner as in Example 1, except that the following coating agent was mixed and the mass ratio of polyester resin (A) / polyvinyl alcohol resin (B) was changed to 100/0. A system film was obtained.
Water 50.62% by mass
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 16.66 mass%
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Comparative Example 2
Acrylic for protecting the polarizer in the same manner as in Example 1, except that the following coating agent was mixed and the mass ratio of polyester resin (A) / polyvinyl alcohol resin (B) was changed to 0/100. A system film was obtained.
17.28% by mass of water
Isopropanol 30.00% by mass
Polyvinyl alcohol aqueous solution (Bw-4) 50.00 mass%
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Comparative Example 3
An acrylic film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion was changed to an aqueous dispersion (Aw-4) in which a polyester resin having an acid value of 25 KOHmg / g was dispersed.

Comparative Example 4
An acrylic film for protecting a polarizer was obtained in the same manner as in Example 1 except that the aqueous polyvinyl alcohol solution was changed to an aqueous solution (Bw-1) in which polyvinyl alcohol having a saponification degree of 88 mol% was dissolved.

Comparative Example 5
An acrylic film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyvinyl alcohol aqueous solution was changed to an aqueous solution (Bw-7) in which polyvinyl alcohol having a saponification degree of 40 mol% was dissolved.

Comparative Example 6
An acrylic film for protecting a polarizer was obtained in the same manner as in Example 1 except that the following coating agent was mixed and the crosslinking agent was not mixed.
41.58% by mass of water
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 11.67 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 15.00 mass%
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Reference example 1
The result of having performed the said adhesiveness test using a TAC film (The Fuji Film Co., Ltd. product, thickness 80 micrometers, saponification process finished) as a polarizer protective film is shown.

  The easy-adhesive acrylic film for protecting a polarizer of the present invention has high adhesiveness with a polarizer / water-based adhesive and high transmittance, and can be suitably used as a polarizer protecting member.

Claims (5)

An acrylic film for protecting a polarizer having an easy-adhesion layer with a polarizer,
The easy-adhesion layer contains a polyester resin (A), a polyvinyl alcohol resin (B), and a crosslinking agent (C),
The crosslinking agent (C) is an isocyanate compound or a melamine compound,
The acid value of the polyester resin (A) is 20 KOHmg / g or less,
The polyvinyl alcohol saponification degree of the resin (B) is Ri 60 to 85 mol% der,
An acrylic film for protecting a polarizer, wherein a mass ratio of the polyester resin (A), the polyvinyl alcohol resin (B), and the crosslinking agent (C) satisfies the following formula in the easy adhesion layer .
0.8 ≦ (A) / (B) ≦ 5
10 ≦ ((A) + (B)) / (C) ≦ 30 The polyester-based resin (A) contains 1 to 15 mole% in the dicarboxylic acid component of 5-sulfoisophthalic acid component, a polarizer protective acrylic film according to claim 1. A polarizing plate having a polarizer protective film on both sides of a polarizer,
The polarizing plate whose at least one polarizer protective film is the acrylic film for polarizer protection of Claim 1 or 2 . A polarizing plate having a polarizer protective film on both sides of a polarizer,
At least one polarizer protective film is the acrylic film for protecting a polarizer according to claim 1 or 2 ,
The polarizing plate whose other polarizer protective film is an oriented polyester film which has a retardation of 3000-30000 nm. An image display device having a polarizing plate according to claim 3 or 4, wherein.