KR20140015346A - Highly adhesive polyester film for protection of polarizers - Google Patents

Abstract

Provided is an easily-adhesive polyester film for polarizer protection excellent in adhesiveness with a polarizer. A polyester film having an adhesive layer on at least one side, the adhesive layer contains a polyester resin (A), a polyvinyl alcohol resin (B), and a crosslinking agent (C), and the polyester resin (A) The easily-adhesive polyester film for polarizer protection whose acid value is 20 KOHmg / g or less and whose saponification degree of the said polyvinyl alcohol-type resin (B) is 60-85 mol%.

Description

Highly adhesive polyester film for protection of polarizers}

This invention relates to the easily-adhesive polyester film for polarizer protection used for protection of a polarizer. Specifically, it is related with the easily adhesive polyester film for polarizer protection excellent in adhesiveness with a polarizer.

In a liquid crystal display device, the polarizing plates are arrange | positioned at both sides of the glass substrate which forms the liquid crystal panel surface from the image formation system. A polarizing plate generally has the structure which bonded together the polarizer protective film on both surfaces of the polarizer which consists of a polyvinyl alcohol-type film and dichroic materials, such as iodine, through hydrophilic adhesives, such as polyvinyl alcohol-type resin. As a protective film used for the protection of a polarizer, the triacetyl cellulose film has conventionally been used from an optical characteristic or transparency viewpoint.

However, triacetyl cellulose is not sufficiently durable, and when the polarizing plate using a triacetyl cellulose film as a polarizer protective film is used under high temperature or high humidity, the performance of polarizing plates, such as polarization degree and a hue, may fall. In addition, in order to cope with thinning of displays recently, thinning of a polarizing plate is required, but there has been a limitation in thinning a triacetyl cellulose film in view of maintaining moisture barrier properties. It is proposed to use a polyester film as a polarizer protective film which has durability and water barrier property to this (refer patent document 1-5).

The triacetyl cellulose film used as a polarizer protective film has an alkali treatment etc. on the surface, and has very high affinity with a hydrophilic adhesive agent. Therefore, the protective film which consists of a triacetyl cellulose film has very high adhesiveness with the polarizer to which the hydrophilic adhesive agent was apply | coated. However, the polyester film has insufficient adhesiveness with a hydrophilic adhesive agent, and the tendency becomes more remarkable especially in the case of the polyester film which has an orientation by an extending | stretching process. Therefore, in patent documents 1-3 and 5, in order to improve adhesiveness with a hydrophilic adhesive agent apply | coated to a polarizer or a polarizer, providing an easily bonding layer in a polyester film is proposed.

Japanese Patent Laid-Open No. 8-271733 Japanese Patent Laid-Open No. 8-271734 Japanese Patent Publication No. 2009-157361 Japanese Patent Publication No. 2010-277028 Japanese Patent Publication No. 2011-8170

The polyester film has low affinity for water, and the polyester film having an aromatic dicarboxylic acid as the dicarboxylic acid component is particularly remarkable in this tendency. Moreover, the polyester film which has crystal orientation by extending | stretching has lower affinity with water. On the other hand, as for the adhesive agent apply | coated on a polarizer or a polarizer, polyvinyl alcohol-type resin has high hydrophilicity as a main component. From such a difference in properties, the polyester film, the polarizer, and the adhesive have low affinity, making it difficult to firmly adhere the two. Therefore, even if it is the polyester film which has an easily bonding layer disclosed by patent documents 1-3 and 5, sufficient adhesiveness was not yet acquired compared with a triacetyl cellulose film. Therefore, when a polarizing plate using a conventional polyester film as a protective film is used for a long time as a display member, lifting or peeling occurs between the protective film and the polarizer, and the polarization characteristic is lowered due to the change in the amount of moisture in the polarizer, and the visibility of white hair, etc. There was a case of deterioration.

Under this current situation, an object of the present invention is to provide a polyester film having a means for firmly bonding a polyester film and a polyvinyl alcohol-based resin layer such as an adhesive applied on a polarizer.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly researched and examined in order to solve the said subject, and the polyvinyl alcohol-type resin and crosslinking agent which have high affinity of the polyester resin with high affinity with a polyester film, and a polyvinyl alcohol-type resin layer are provided. The spherical structure of providing the layer containing between a polyester film and a polyvinyl alcohol-type resin layer was reached. However, the present inventors have found that the function of bringing the polyester film and the polyvinyl alcohol-based resin layer by each component into close contact with each other simply by combining them is not sufficiently exhibited. The inventors of the present invention have repeatedly studied day and night, by adopting a polyester resin having a certain acid value as the polyester resin in the above concept, and a polyvinyl alcohol resin having a certain degree of saponification as a polyvinyl alcohol-based resin It discovered that the adhesive effect with the resin layer with high affinity by each component can be exhibited effectively.

The present inventors have conducted further studies based on the above findings, and as a result, employing a crosslinking agent highly reactive with hydroxyl groups allows the polyester film and the polyvinyl alcohol-based resin layers such as polarizers and adhesives to be more firmly bonded. Found it possible. The present inventors have repeatedly invented the present invention by further examining and improving on the basis of these findings.

The representative example of this invention is shown below.

1st invention is a polyester film which has an easily bonding layer on at least one side, Comprising: This easily bonding layer contains polyester resin (A), polyvinyl alcohol-type resin (B), and a crosslinking agent (C), The said polyester-type resin The acid value of (A) is 20 KOHmg / g or less, and it is the easily adhesive polyester film for polarizer protection whose saponification degree of the said polyvinyl alcohol-type resin (B) is 60-85 mol%.

2nd invention is the said easily-adhesive polyester film for polarizer protections in which the said polyester resin (A) contains 1-15 mol% of 5-sulfoisophthalic acid components in a dicarboxylic acid component.

3rd invention is the easily-adhesive polyester film for polarizer protection whose said crosslinking agent (C) is an isocyanate compound or a melamine compound.

4th invention is the said easily-adhesive polyester film for polarizer protection in which the mass ratio of polyester-based resin (A), polyvinyl alcohol-type resin (B), and a crosslinking agent (C) in the said easily bonding layer satisfy | fills following formula.

5th invention is a polarizing plate which has a polarizer protective film on both surfaces of a polarizer, and is a polarizing plate whose at least one polarizer protective film is the said easily-adhesive polyester film for polarizer protection.

The easily adhesive polyester film for polarizer protection of this invention is excellent in adhesiveness with the polyvinyl alcohol-type resin layer represented by the polarizer or the adhesive agent apply | coated on it. Therefore, the polyester film of this invention can be used suitably as a protective film of a polarizer. By using the polyester film of this invention as a protective film of a polarizer, it is possible to manufacture a polarizing plate excellent in durability and water barrier property more cheaply than before. In addition, since the polarizing plate of the present invention is excellent in durability, it is possible to further reduce the thickness of the polarizing plate. Therefore, it is possible to further thin a liquid crystal display by using the polarizing plate of this invention.

(Polyester film)

The polyester film used as a base material in this invention is a film mainly comprised from a polyester resin. Here, "a film mainly composed of a polyester resin" is a film formed from a resin composition containing 50 mass% or more of polyester resin, and when blended with another polymer, it means that the polyester resin contains 50 mass% or more. In addition, when copolymerizing with another monomer, it means containing 50 mol% or more of polyester structural units. Preferably, a polyester film contains 90 mass% or more of polyester resin, More preferably, it is 95 mass% or more, More preferably, it contains 100 mass%.

Although a material is not specifically limited as polyester resin, The copolymer formed by polycondensation of a dicarboxylic acid component and a diol component, or its blend resin can be used. As the dicarboxylic acid component, for example, terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5 -Naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxy ethane dicarboxylic acid, diphenyl sulfone carboxylic acid, anthracenedicarboxylic 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-dimethyl glutaric acid, adipic acid, 2-methyl adipic acid, trimethyl adipic acid, pimelic acid, azelaic acid, dimer acid, sebacic acid, suberic acid, dodecadicarboxylic acid, etc. are mentioned.

As the diol component constituting the polyester resin, for example, ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decamethylene glycol, 1, 3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone and the like Can be mentioned.

The dicarboxylic acid component and diol component which comprise a polyester resin may use 1 type, or 2 or more types, respectively. Moreover, you may add other acid components, such as trimellitic acid, and other hydroxyl group components, such as trimethylolpropane.

Specific examples of the polyester resin include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and the like. Among them, polyethylene terephthalate is preferable from the balance of physical properties and cost. Moreover, in order to control optical characteristics, such as polarization property, it is also a preferable aspect to include another copolymerization component and another polymer. As a preferable copolymerization component from a viewpoint of controlling the optical characteristic of a polyester film, the copolymerization component etc. which have norbornene in diethylene glycol and a side chain are mentioned.

Since the polyester film of this invention is used as a protective film for polarizers, it is preferable to have high transparency. The transparency of the polarizer protective polyester film of the present invention is preferably 85% or more in total light transmittance, more preferably 87% or more, still more preferably 88% or more, still more preferably 89% or more, 90% or more This is particularly preferred. Moreover, it is preferable that haze is 3% or less, 2.5% or less is more preferable, 2% or less is still more preferable, 1.5% or less is especially preferable. The total light transmittance of a polyester film can be measured according to the method described in the Example mentioned later, for example.

In order to improve handling properties such as slipperiness and winding property of polyester film, inert particles may be included in the film, but in order to maintain high transparency, the content of inert particles in the film may be as long as possible. Less is preferable. Therefore, it is preferable to have a multi-layered structure in which particles are contained only in the surface layer of the film, or to contain the fine particles only in the easily adhesive layer laminated on at least one side of the polyester film without substantially containing the particles in the film.

The term "substantially free of particles" means, for example, that inorganic particles are 50 ppm or less, preferably 10 ppm or less, most preferably when quantitatively analyzing elements derived from particles by fluorescence X-ray analysis. It means content which becomes below a detection limit. This is because contaminants derived from foreign foreign substances, raw material resins, or contaminants adhering to lines or apparatuses in the manufacturing process of the film may be peeled off and mixed into the film even if particles are not actively added to the base film.

In the case where the base film has a multilayer structure, the two-layer three-layer structure containing inert particles only in the outermost layer without substantially containing inert particles in the inner layer can be made compatible with transparency and processability.

Although the thickness of a film is not specifically limited in this invention, When thickness of a polarizing plate is made thin for thickness of a display, it is preferable that the thickness of a film is 200 micrometers or less, and it is more preferable that it is 100 micrometers or less. On the other hand, in order to maintain the mechanical strength as a protective film, it is preferable that the thickness of a film is 10 micrometers or more, It is more preferable that it is 12 micrometers or more, It is further more preferable that it is 20 micrometers or more.

The polyester film serving as the substrate may be a single layer or may be a laminate of two or more kinds of layers. Moreover, if it is in the range which shows the effect of this invention, various additives can be contained in a film as needed. As an additive, antioxidant, a light resistant agent, an antigelling agent, an organic wetting agent, an antistatic agent, a ultraviolet absorber, surfactant, etc. are mentioned, for example. When a film has a laminated structure, it is also preferable to contain an additive according to the function of each layer as needed. For example, in order to prevent photodegradation of a polarizer, it is also a preferable aspect to add a ultraviolet absorber etc. to an inner layer.

A polyester film is obtained by the method of melt-extruding the said polyester resin in film form, for example, by cooling and solidifying with a casting drum, and forming a film. As the polyester film of the present invention, either an unstretched film or a stretched film can be used, but it is preferably a stretched film from the viewpoint of durability such as mechanical strength and chemical resistance. When a polyester film is a stretched film, the extending | stretching method is not specifically limited, A longitudinal uniaxial stretching method, a lateral uniaxial stretching method, a horizontal and vertical uniaxial biaxial stretching method, a horizontal and simultaneous simultaneous biaxial stretching method, etc. can be employ | adopted.

(Adhesive layer)

The polyester film of the present invention is a polyester resin having an acid value of 20 KOHmg / g or less on at least one side thereof, in order to improve adhesiveness with a polarizer and a polyvinyl alcohol resin layer such as an aqueous adhesive agent provided on one side or both sides thereof. (A), the easily bonding layer formed from the resin composition containing polyvinyl alcohol-type resin (B) and crosslinking agent (C) whose saponification degree is 60-85 mol% is laminated | stacked. An easily bonding layer may be provided in both surfaces of a polyester film, may be provided only in the single side | surface of a polyester film, and a heterogeneous resin coating layer may be provided in the other surface.

Although not bound by theory, a combination of a specific polyester resin (A) having a saponification degree of 20 KOHmg / g or less, a specific polyvinyl alcohol resin (B) having a saponification degree of 60 to 85 mol%, and a crosslinking agent (C) By doing so, it is considered that the polyester resin and the polyvinyl alcohol resin form separate domain units in the easily adhesive layer, respectively, to form a phase-separated structure, also commonly referred to as a sea island structure. By taking the separation structure of such a domain unit, adhesiveness with the polyester film by the domain comprised by polyester resin and adhesion with the polyvinyl alcohol-type resin layer by the domain comprised by polyvinyl alcohol-type resin It is thought that the two functions, sex, are intact and compatible. It is thought that the crosslinking agent (C) promotes and maintains the formation of the domain structure by crosslinking and agglomerating the polyvinyl alcohol-based resin (B).

Hereinafter, each composition of an easily bonding layer is demonstrated in detail.

(Polyester Resin (A))

Polyester-based resin (A) used for the easily bonding layer of this invention is a copolymer formed by polycondensation of a dicarboxylic acid component and a diol component, As a dicarboxylic acid component and a diol component, the material of the polyester film as the base material mentioned above Can be used. From the viewpoint of improving the adhesiveness with the polyester film base material, the dicarboxylic acid component having the same or similar structure and properties as the dicarboxylic acid component in the polyester film as the base material can be used as the dicarboxylic acid of the polyester resin (A). It is preferable to use as an acidic component. Therefore, when aromatic dicarboxylic acid is employ | adopted as a dicarboxylic acid component of a polyester film, for example, it is preferable to use aromatic dicarboxylic acid as a dicarboxylic acid component of polyester-based resin (A). As such aromatic dicarboxylic acid component, terephthalic acid and isophthalic acid are most preferred. You may add and copolymerize another aromatic dicarboxylic acid in 10 mol% or less with respect to all the dicarboxylic acid components.

Moreover, as a glycol component of polyester-type resin (A), it is preferable to use ethylene glycol and the branched glycol as a structural component. By having a branched structure, it is thought that it is possible to contribute to the stress relaxation in an easily bonding layer, and to show adhesiveness suitably. The branched glycol component is, for example, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 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 , 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 Can be mentioned.

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, it is preferable that an upper limit is 80 mol%, More preferably, it is 70 mol%, Especially preferably, it is 60 mol%. Moreover, you may use together diethylene glycol, propylene glycol, butanediol, hexanediol, 1, 4- cyclohexane dimethanol, as needed.

It is preferable to use water-soluble or water dispersible resin for polyester-based resin (A) used by this invention from a compatibility viewpoint with polyvinyl alcohol-type resin (B). For water solubilization or water oxidation of polyester resin, it is preferable to copolymerize the compound containing hydrophilic groups, such as a sulfonate group and a carboxylate group. Especially, the dicarboxylic acid component which has a sulfonate group is suitable from a viewpoint of providing hydrophilicity, keeping the acid value of polyester-based resin (A) low and controlling reactivity with a crosslinking agent. Examples of the dicarboxylic acid component having a sulfonate group include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfonaphthalene isophthalic acid-2,7-dicarboxylic acid and 5- (4-sulfophenoxy) isophthalic acid. Or alkali metal salts thereof, and among them, 5-sulfoisophthalic acid is preferable. 1-15 mol% is preferable in the dicarboxylic acid component of a polyester resin (A), as for the dicarboxylic acid component which has a sulfonate group, 1.5-12 mol% is more preferable, and its 2-10 mol% is further more preferable. Do. When the dicarboxylic acid component which has a sulfonate group is more than the said minimum, it is suitable for water solubilization or water oxidation of a polyester-type resin. Moreover, when the dicarboxylic acid component which has a sulfonate group is below the said upper limit, it is suitable for adhesiveness with a polyester film base material.

It is more preferable that polyester-based resin (A) has few carboxylic acid groups which are reactors with a crosslinking agent (C). Since the reactivity with the crosslinking agent is lowered by reducing the carboxyl group which is reactive with the crosslinking agent, it is consequently to maintain the domain structure formed by the crosslinked polyvinyl alcohol-based resin because it is not completely mixed with the polyvinyl alcohol-based resin. I think it's possible. From this point of view, 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, more preferably 8 KOHmg / g or less, more More preferably, it is 5 KOHmg / g or less. The acid value of polyester-based resin (A) can be theoretically calculated | required from the result of component analysis by the titration method mentioned later, NMR, etc.

In order to control the acid value of polyester-based resin (A) to the said range, the introduction amount of carboxylate group for water solubilization or water oxidation is reduced, a hydrophilic group other than a carboxylate group is employ | adopted, or carboxyl of a polyester-type resin is used. It is desirable to lower the acid terminal concentration. As a method of decreasing the carboxylic acid terminal concentration of polyester-type resin, it is preferable to employ | adopt polyester-type resin which terminal-modified the carboxylic acid terminal group, or employ | adopt polyester resin with a large number average molecular weight of polyester-type resin. Do. For this reason, it is preferable that the number average molecular weight of polyester-based resin (A) is 5000 or more, It is more preferable that it is 6000 or more, 10000 or more are more preferable. Moreover, it is preferable to make content of the acid component which has three or more carboxyl groups as polyester component (A) a structural component.

Although the glass transition temperature of polyester-based 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. If glass transition temperature is more than the said minimum, it is suitable with respect to blocking resistance, and if glass transition temperature is below the said upper limit, it is suitable with respect to adhesiveness with a polyester film base material.

40 mass% or more and 90 mass% or less are preferable, as for content of polyester-based resin (A) in an easily bonding layer, 45 mass% or more and 85% mass% or less are more preferable, 50 mass% or more and 80 mass% or less More preferred. It is suitable for adhesiveness with a polyester film base material as content of polyester-type resin (A) is more than the said minimum, and below the said upper limit, it is suitable for adhesiveness with polyvinyl alcohol-type resins, such as a polarizer and a hydrophilic adhesive agent.

(Polyvinyl Alcohol Resin (B))

The polyvinyl alcohol-based resin is not particularly limited, but for example, polyvinyl alcohol obtained by saponifying polyvinyl acetate; derivatives thereof; saponification of a copolymer with vinyl acetate and a copolymerizable monomer; acetalization of polyvinyl alcohol And modified polyvinyl alcohols obtained by urethaneization, etherification, grafting, phosphate esterification, and the like. Examples of the monomer include unsaturated carboxylic acids such as maleic anhydride, fumaric acid, crotonic acid, itaconic acid and (meth) acrylic acid and esters thereof; α-olefins such as ethylene and propylene, and (meth) allylsulfonic acid (soda) , Sodium sulfonic acid (monoalkyl maleate), disulfonic acid sodium alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinylpyrrolidone, N-vinylpyrrolidone derivative, and the like. Can be mentioned. 1 type of these polyvinyl alcohol-type resins may be used, or may use 2 or more types together.

Examples of the polyvinyl alcohol-based resin (B) used in the present invention include vinyl alcohol-vinyl acetate copolymers, vinyl alcohol-vinyl butyral copolymers, and ethylene-vinyl alcohol copolymers, among which vinyl alcohol-vinyl acetate copolymers. And ethylene-vinyl alcohol copolymers are preferred. Although the polymerization degree of polyvinyl alcohol-type resin (B) is not specifically limited, It is preferable that polymerization degree is 3000 or less from a viewpoint of coating liquid viscosity.

The copolymerization ratio of vinyl alcohol is shown by saponification degree. As for the saponification degree of the polyvinyl alcohol-type resin (B) of this invention, 60 mol% or more and 85 mol% or less are preferable, 65 mol% or more and 83 mol% or less are more preferable, 68 mol% or more and 80 mol% or less further It is preferable, 70 mol% or more and less than 80 mol% is still more preferable, 71 mol% or more and 78 mol% or less are still more preferable, 73 mol% or more and 75 mol% or less are especially preferable. If the saponification degree of polyvinyl alcohol-type resin (B) is more than the said minimum, a crosslinked structure can be formed more suitably with a crosslinking agent (C). Moreover, when saponification degree of polyvinyl alcohol-type resin (B) is below the said upper limit (or less), it can show compatibility suitably with polyester-type resin (A). The saponification degree of vinyl alcohol-type resin can be calculated | required by the alkali consumption amount required for hydrolysis of copolymerization units, such as vinyl acetate, and the composition analysis by NMR.

As content of polyvinyl alcohol-type resin (B), 10 mass% or more and 60 mass% or less are preferable in an easily bonding layer, 15 mass% or more and 55% mass% or less are more preferable, 20 mass% or more and 50 mass% or less are furthermore. desirable. When content of polyvinyl alcohol-type resin (B) is more than the said minimum, it is suitable for adhesiveness with polyvinyl alcohol-type resin layers, such as a polarizer and an adhesive agent, and below the said upper limit, it is suitable for adhesiveness with a polyester film base material.

(Cross-linking system (C))

Although it will not specifically limit, if it has a hydroxyl group and crosslinkability as a crosslinking agent (C), The compound, such as a melamine type, an isocyanate type, a carbodiimide type, an oxazoline type, an epoxy type, is mentioned. From the viewpoint of the stability over time of the coating liquid, a compound of melamine type, isocyanate type, carbodiimide type, or oxazoline type is preferable. Moreover, it is preferable that a crosslinking agent is a melamine type compound or an isocyanate type compound which crosslinks reaction suitably with the hydroxyl group of polyvinyl alcohol-type resin (B). This is because the carbodiimide crosslinking agent reacts with the carboxyl group, whereas the melamine compound or the isocyanate compound reacts with the hydroxyl group, and thus forms a crosslinked structure more suitably with the polyvinyl alcohol-based resin (B) having a hydroxyl group as a functional group. I think. Especially, it is especially preferable to use an isocyanate type compound from a viewpoint of forming a crosslinking reaction suitably with the hydroxyl group of polyvinyl alcohol-type resin, and being excellent in transparency. Moreover, in order to accelerate crosslinking reaction, you may use a catalyst etc. suitably as needed.

As the isocyanate compound, a low molecular or high diisocyanate or a trivalent or higher polyisocyanate can be used. For example, as an isocyanate compound, 2, 4- tolylene diisocyanate, 2, 6- tolylene diisocyanate, 4,4'- diphenylmethane diisocyanate, 2,4'- diphenylmethane diisocyanate, 2,2'-di Phenylmethane 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'-di Aromatic diisocyanates such as phenyl propane diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, aromatic aliphatic diisocyanates such as xylylene diisocyanate, isophorone diisocyanate and 4,4- Dicyclohexyl methane diisocyanate, Alicyclic diisocyanates such as 1,3-bis (isocyanate methyl) cyclohexane, aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate and trimers of these isocyanate compounds Can be. In addition, an excessive amount of these isocyanate compounds and low molecular weight active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, or polyester polyols, poly The terminal isocyanate group containing compound of the polymer obtained by making high molecular weight active hydrogen compounds, such as ether polyols and polyamides, react is mentioned.

As a melamine compound, the melamine compound substituted by the substituent-(CH2) nOR (wherein n is an integer of 1-3 and R is a C1-C4 alkyl group) is mentioned, R in said formula becomes like this. Methyl. Preferably the number of the said substituents which one melamine structure has is 3-6. As a specific example of a melamine compound, M-3, MK, M-6, M-100, MC etc. which are Sumitex resin series by Sumitomo Chemical Co., Ltd., methylated melamine resin MW-22, MX-706, MX-042 by Sanwa Chemical Co., Ltd. Etc. can be mentioned.

As a crosslinking agent (C) used for this invention, a block isocyanate type compound is also preferable. By adding a block isocyanate type compound, it becomes possible to improve the time-lapse stability of a coating liquid more suitably.

The blocked isocyanate compound can be prepared by addition reaction of the isocyanate compound and the blocking agent by a conventionally known method. As the isocyanate blocking agent, for example, phenols such as phenol, cresol, xylenol, resorcinol, nitrophenol and chlorophenol; thiophenols such as thiophenol and methylthiophenol; acetoxime, methyl ethyl ketoxime and cyclohexanone Oximes such as oximes; alcohols such as methanol, ethanol, propanol and butanol; halogen substituted alcohols such as ethylenechlorohydrin and 1,3-dichloro-2-propanol; agents such as t-butanol and t-pentanol Tertiary alcohols; lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propyllactam; aromatic amines; imides; acetylacetone, acetoacetic acid ester, and malonic acid ethyl ester Active methylene compounds; mercaptans; imines; ureas; diaryl compounds; sodium bisulfite and the like.

As content of a crosslinking agent (C), 2 mass% or more and 50 mass% or less are preferable in an easily bonding layer, 5 mass% or more and 40% mass% or less are more preferable, 8 mass% or more and 30 mass% or less are more preferable. If content of a crosslinking agent (C) is more than the said minimum, it is suitable for bridge | crosslinking formation of polyvinyl alcohol-type resin, and below the said upper limit, it is suitable for expression of the adhesive effect by binder resin.

It is preferable that the compounding ratio (A) / (B) of polyester-type resin (A) and polyvinyl alcohol-type resin (B) is 0.8-5 by mass ratio, It is more preferable that it is 1-4, It is 2-4 More preferably, it is especially preferable that it is 2.5-3.5. When (A) / (B) is more than the said minimum, it is suitable for adhesiveness with a polyester film base material, and below this upper limit is suitable for adhesiveness with polyvinyl alcohol-type resin layers, such as a polarizer and an adhesive agent.

It is preferable that the compounding ratio ((A) + (B)) / (C) of polyester-type resin (A), polyvinyl alcohol-type resin (B), and a crosslinking agent (C) is 2-50 in mass ratio, and 5-40 It is more preferable that it is, and it is further more preferable that it is 8-30. When ((A) + (B)) / (C) is more than the said minimum, it is suitable for expression of the adhesive effect by a binder resin component, and below this upper limit is suitable for the adhesive effect by phase separation.

The easily bonding layer of this invention employ | adopts the said composition, and exhibits the high adhesiveness equivalent to triacetyl cellulose with respect to a polarizer and an aqueous adhesive, especially a polyvinyl alcohol-type polarizer and an aqueous adhesive agent. Specifically, the water-retained area after peeling once with respect to the water-based adhesive agent by the adhesive test described later is preferably 90% or more, more preferably 95% or more, still more preferably 100%, and remaining after 5 consecutive peelings. The area is preferably at least 75%, more preferably at least 85%, even more preferably at least 95%, and the remaining area after ten successive peels is preferably at least 50%, more preferably at least 80%, further It is preferably at least 90%, even more preferably at least 93%, particularly preferably at least 95%.

(additive)

In the easily-adhesive layer of the present invention, known additives such as surfactants, antioxidants, catalysts, heat stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricating agents, etc., within a range that does not impair the effects of the present invention, You may add a pigment, dye, organic or inorganic particle, an antistatic agent, a nucleating agent, etc.

In this invention, in order to improve the blocking resistance of an easily bonding layer further, it is also a preferable aspect to add particle | grains to an easily bonding layer. In the present invention, the particles contained in the easily adhesive layer include, for example, titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, and the like, or mixtures thereof. For example, inorganic particles such as calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, calcium fluoride and the like, and organic polymer particles such as styrene, acrylic, melamine, benzoguanamine and silicon Can be mentioned.

The average particle diameter of the particles in the easily adhesive layer (average particle diameter based on the number based on the 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 diameter of the inert particles is less than 0.04 µm, the formation of irregularities on the surface of the film is insufficient, and thus handling properties such as slipperiness and winding property of the film may be deteriorated, and workability at the time of bonding may be reduced. On the contrary, when it exceeds 2.0 micrometers, particle | grains will fall easily and it is unpreferable. It is preferable that it is 1-20 mass% in solid component, and, as for the particle concentration in an easily bonding layer, it is more preferable that it is 5-15 mass%.

In this invention, although the thickness of an easily bonding layer can be suitably set in 0.001-2.00 micrometers, in order to make workability and adhesiveness compatible, the range of 0.01-1.00 micrometers is preferable, More preferably, it is 0.02-0.80 micrometer, More preferably, Preferably it is 0.05-0.50 micrometer. Adhesiveness becomes inadequate when the thickness of an easily bonding layer is less than 0.01 micrometer. When the thickness of an easily bonding layer exceeds 2.00 micrometers, blocking may arise.

(Manufacture of easily adhesive polyester film for polarizer protection)

Although the polyethylene terephthalate (it abbreviates as PET) film is demonstrated to an example about the manufacturing method of the easily adhesive polyester film for polarizer protection of this invention, it is not necessarily limited to this.

After sufficiently drying the PET resin in vacuum, the extruder is supplied to an extruder to melt-extrude the molten PET resin at about 280 ° C. from the T die in a sheet form on a rotary cooling roll, and to cool and solidify by electrostatic application to obtain an unstretched PET sheet. The unstretched PET sheet may have a single layer structure or a multilayer structure by a coextrusion method.

The obtained unoriented PET sheet is crystallized by performing uniaxial stretching or biaxial stretching. For example, in the case of biaxial stretching, the film is stretched 2.5 to 5.0 times in the length direction with a roll heated to 80 to 120 ° C. to obtain a uniaxially stretched PET film. Then, the end of the film is gripped with a clip and heated to 80 to 180 ° C. Induce to and stretch in 2.5 ~ 5.0 times in the width direction. In the case of uniaxial stretching, the stretching is performed 2.5 to 5.0 times in the tenter. After stretching, it is continuously led to a heat treatment zone of 140 ~ 240 ℃ to perform a heat treatment for 1 to 60 seconds to complete the crystal orientation.

An easily bonding layer can be provided after manufacture of a film, or in a manufacturing process. In particular, from the viewpoint of productivity, it is preferable to apply the coating liquid to at least one side of the PET film after any step of the film manufacturing process, that is, unstretched or uniaxially stretched, to form an easily adhesive layer.

As a method for applying this coating liquid to a PET film, any known method can be used. 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. Can be mentioned. These methods can be coated alone or in combination.

It is preferable that the thickness of the easily bonding layer finally obtained in this invention is 0.03-0.20 g / m <2>. If it is less than 0.03 g / m <2>, adhesiveness falls and it is unpreferable because thicker than 0.20 g / m <2>, blocking property and slipperiness will fall.

(Polarizer)

The polarizing plate of this invention is a polarizing plate which has a polarizer protective film on both surfaces of a polarizer, It is preferable that the polarizer protective film of at least one surface is the easily adhesive polyester film for polarizer protection. The other polarizer protective film may be an easily adhesive polyester film for polarizer protection of the present invention, and it is also preferable to use a film having no birefringence represented by a triacetyl cellulose film, an acrylic film, or a norbornene-based film.

As a polarizer, what contains dichroic materials, such as iodine, in a polyvinyl alcohol-type film is mentioned, for example. Although a polarizer protective film is bonded together with a polarizer directly or via an adhesive bond layer, it is preferable to paste together an adhesive agent from a viewpoint of adhesive improvement. In that case, it is preferable that the easily bonding layer of this invention is arrange | positioned at a polarizer surface or an adhesive bond layer surface. As a polarizer suitable for bonding the polyester film of the present invention, for example, a polyvinyl alcohol-based film is dyed and adsorbed with iodine or a dichroic material, uniaxially stretched in an aqueous solution of boric acid, and washed and dried while maintaining the stretched state. The polarizer obtained by performing is mentioned. The draw ratio of uniaxial stretching is about 4 to 8 times normally. As a polyvinyl alcohol-type film, polyvinyl alcohol is suitable, and "Kurere vinylon" [Kurare Co., Ltd.], "Tocelo vinylon" [Tocello Co., Ltd.], "Nichigo vinylon" [Japan synthetic chemistry] Commercially available products, such as (manufactured by Co., Ltd.) can be used. Examples of the dichroic material include iodine, disazo compounds, polymethine dyes, and the like.

It is preferable that the adhesive agent apply | coated to a polarizer is water-based from the viewpoint of thinning an adhesive bond layer, ie, what melt | dissolved the adhesive component in water, or disperse | distributed to water. For example, a polyvinyl alcohol-based resin, a urethane resin, or the like may be used as the main component, and a composition containing an isocyanate compound, an epoxy compound, or the like may be used if necessary in order to improve adhesion. 10 micrometers or less are preferable, as for the thickness of an adhesive bond layer, 5 micrometers or less are more preferable, and its 3 micrometers or less are more preferable.

When polyvinyl alcohol-based resin is used 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 polyvinyl alcohol You may use modified polyvinyl alcohol-type resin like vinyl alcohol. 1-10 mass% is preferable, and, as for the density | concentration of polyvinyl alcohol-type resin in an adhesive agent, 2-7 mass% is more preferable.

Example

Next, although an Example, a comparative example, and a reference example demonstrate this invention in detail, this invention is not limited to a following example naturally. In addition, the evaluation method used in the present invention is as follows.

(1) glass transition temperature

Extrapolated glass transition obtained from a DSC curve by heating 10 mg of the resin sample at 20 ° C / min over a temperature range of 25 to 300 ° C using a differential scanning calorimeter (Seiko Instruments, DSC6200) in accordance with JIS K7121. The starting temperature was taken as the glass transition temperature.

(2) number average molecular weight

0.03 g of resin was dissolved in 10 ml of tetrahydrofuran, and the column temperature was 30 DEG C, flow rate 1 ml / min, using a GPC-LALLS device low angle light scattering photometer LS-8000 (manufactured by Tosoh Corporation, tetrahydrofuran solvent, reference: polystyrene). The number average molecular weight was measured using the column (shodex KF-802, 804, 806 by Showa Denko).

(3) resin composition

The resin was dissolved in heavy chloroform and subjected to ¹ H-NMR analysis using a Varian Nuclear Magnetic Resonance Spectrometer (NMR) Gemini-200 to determine the molar percentage ratio of each composition from the integral ratio.

(4) acid value

Amount of KOH (mg) required to neutralize carboxyl groups per gram of sample by dissolving 1 g (solid) sample in 30 ml of chloroform or dimethylformamide, titrating with 0.1 N potassium hydroxide ethanol solution with phenolphthalein as an indicator. ) Was obtained.

(5) saponification degree

According to JIS-K6726, the residual acetic acid group (mol%) of polyvinyl alcohol resin was quantified using sodium hydroxide, and the value was made into saponification degree (mol%). It measured 3 times about the said sample, and made the average value into saponification degree (mol%).

(6) Total light transmittance of polyester film for polarizer protection

The total light transmittance of the polyester film for polarizer protection was measured using the turbidity meter (made by Nippon Color Corporation, NDH2000) based on JISK7105.

(7) Haze of polyester film for polarizer protection

The haze of a polarizer protective polyester film was measured using the turbidity meter (made by Nippon Color Corporation, NDH2000) based on JISK7136.

(8) PVA adhesive

Polyvinyl alcohol aqueous solution (PVA117 by Kuraray) adjusted to solid content concentration 5 mass% on the easily bonding layer surface of the polarizer protective polyester film was apply | coated with a wire bar so that the thickness of the polyvinyl alcohol resin layer after drying might be 2 micrometers, and it is 70 degreeC. It was dried for 5 minutes. As a polyvinyl alcohol aqueous solution, what added the red dye was used so that determination might become easy. The opposite surface of the surface in which the polyvinyl alcohol resin layer of the laminated | multilayer film of evaluation object was formed was affixed on the glass plate of thickness 5mm which affixed the double-sided tape on the produced evaluation object film with the said double-sided tape. Subsequently, 100 checkerboard-shaped cutting lines penetrating the polyvinyl alcohol resin layer to reach the base film were drawn using cutter guides having a gap interval of 2 mm. Subsequently, an adhesive tape (Nitro-Reflective Cello Tape (registered trademark) CT-24; 24 mm width) was affixed to the surface which cut the cutting line in the shape of a checkerboard. At the time of sticking, the air remaining at the interface was pressed with an eraser to make it completely adhered, and then the work of peeling off the adhesive tape vertically vigorously was performed once, five times and ten times. The number of board | substrates in which the polyvinyl alcohol resin layer did not peel was counted, and it was set as PVA adhesiveness. That is, the case where PVA layer did not peel at all was made into PVA adhesion rate 100, and when all PVA layers were peeled off, it was set as PVA adhesion rate 0. In addition, the part peeled in one checker eye was also included in the peeled number.

(Polymerization of Polyester Resin)

194.2 parts by mass of dimethyl terephthalate, 184.5 parts by mass of dimethylisophthalate, 14.8 parts by mass of dimethyl-5-sodium sulfoisophthalate, 233.5 parts by mass of diethylene glycol in a stainless steel autoclave equipped with a stirrer, a thermometer, and a partially reflux cooler. 136.6 parts by mass of ethylene glycol and 0.2 part by mass of tetra-n-butyl titanate were added, and a transesterification reaction was carried out at a temperature of 160 ° C to 220 ° C for 4 hours. Subsequently, after heating up to 255 degreeC and depressurizingly reducing a reaction system, it was made to react for 1 hour and 30 minutes under reduced pressure of 30 Pa, and copolymerized polyester resin (A-1) was obtained. The obtained copolyester resin (A-1) was transparent pale yellow. It was 0.70 dl / g when the reduced viscosity of the copolyester resin (A-1) was measured. The glass transition temperature by DSC was 40 degreeC.

Copolymerizing polyester resin (A-2)-(A-5) of the other composition was obtained by the same method. The composition (mol% ratio) and other characteristics measured by <^1> H-NMR about these co-polyester resin are shown in Table 1.

(Preparation of Polyester Water Dispersion)

30 mass parts of polyester resin (A-1) and 15 mass parts of ethylene glycol n-butyl ether were put into the reactor provided with the stirrer, the thermometer, and the reflux apparatus, and it heated and stirred at 110 degreeC, and melt | dissolved resin. After the resin was completely dissolved, 55 parts by mass of water was added slowly with stirring to the polyester solution. After the addition, the liquid was cooled to room temperature while stirring to prepare a milky polyester aqueous dispersion (Aw-1) having a solid content of 30% by mass. Similarly, water dispersions were prepared using polyester resins (A-2) to (A-5) instead of polyester resins (A-1), and polyester water dispersions (Aw-2) to (Aw-5), respectively. It was set as.

(Preparation of polyvinyl alcohol aqueous solution)

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

(Polymerization of Block Polyisocyanate Crosslinking Agent)

100 parts by mass of a polyisocyanate compound (Asahi Chemical Chemicals, Duranate TPA) having an isocyanurate structure using hexamethylene diisocyanate as a raw material in a flask equipped with a stirrer, a thermometer, and a reflux cooling tube, and propylene glycol monomethyl ether 55 parts by mass of acetate and 30 parts by mass of polyethylene glycol monomethyl ether (average molecular weight 750) were added and maintained 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 ketooxime was added dropwise. The infrared spectrum of the reaction solution was measured to confirm that absorption of the isocyanate group was lost, thereby obtaining a blocked polyisocyanate aqueous dispersion (C-1) having a solid content of 75% by mass.

Example 1

(1) Preparation of coating liquid

The following coating agents were mixed to prepare a coating solution in which the mass ratio of the polyester resin (A) / polyvinyl alcohol resin (B) was 70/30. The polyester water dispersion uses an aqueous dispersion (Aw-1) in which a polyester resin having an acid value of 2 KOHmg / g is dispersed (Aw-1), and an aqueous polyvinyl alcohol solution in which polyvinyl alcohol having a saponification degree of 74 mol% is dissolved (Bw). -4) was used.

40.61 mass% of water

Isopropanol 30.00 mass%

Polyester water dispersion (Aw-1) 11.67 mass%

Polyvinyl alcohol aqueous solution (Bw-4) 15.00 mass%

Block isocyanate crosslinking agent (C-1) 0.67 mass%

1.25 mass% of particles

(Silica sol having an average particle diameter of 100 nm, solid content concentration of 40 mass%)

catalyst

0.3 mass% (14 mass% of organic tin compound solid concentration)

0.5 mass% of surfactant

(Silicone system, solid content concentration 10% by mass)

(2) Preparation of polyester film for polarizer protection

PET resin pellets having an intrinsic viscosity (solvent: phenol / tetrachloroethane = 60/40) of 0.62 dl / g and substantially free of particles as a film raw material polymer were dried at 135 ° C. under a reduced pressure of 133 kPa for 6 hours. It was. Thereafter, the resultant was fed to an extruder, melt-extruded into a sheet shape at about 280 ° C., and rapidly quenched and solidified on a rotary cooling metal roll maintained at a surface temperature of 20 ° C. to obtain an unstretched PET sheet.

The unstretched PET sheet was heated to 100 ° C. with a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction with a roll group having a circumferential speed difference to obtain a uniaxially stretched PET film.

Subsequently, the coating liquid was applied to one side of the PET film by a roll coat method, and then dried at 80 ° C. for 15 seconds. Moreover, it adjusted so that the application amount after final (after biaxial stretching) drying might be 0.12 g / m <2>. Subsequently, the film was stretched 4.0 times in the width direction at 150 ° C. with a tenter and heated at 230 ° C. for 0.5 seconds while fixing the length in the width direction of the film. Further, 3% in the width direction was relaxed at 230 ° C. for 10 seconds to give a thickness. A 38 micrometer polarizer protective polyester film was obtained. The evaluation results are shown in Table 3.

Example 2

The polyester film for polarizer protection was obtained like Example 1 except having changed the polyester water dispersion into the water dispersion (Aw-2) in which the polyester resin whose acid value is 4KOHmg / g was disperse | distributed.

Example 3

The polyester film for polarizer protection was obtained like Example 1 except having changed the polyester water dispersion into the water dispersion (Aw-3) which the polyester resin whose acid value is 6KOHmg / g disperse | distributed.

Example 4

The polarizer protective polyester film was obtained like Example 1 except having changed the polyvinyl alcohol aqueous solution into the polyvinyl alcohol aqueous solution (Bw-3) whose saponification degree of polyvinyl alcohol is 79 mol%.

Example 5

The polarizer protective polyester film was obtained like Example 1 except having changed the saponification degree of polyvinyl alcohol into the polyvinyl alcohol aqueous solution (Bw-2) which is 83 mol%.

Example 6

The polyester film for polarizer protection was obtained like Example 1 except having changed the mass ratio of polyester resin (A) / polyvinyl alcohol-type resin (B) so that it may become 60/40, by mixing the following ceramics.

37.28 mass% of water

Isopropanol 30.00 mass%

Polyester water dispersion (Aw-1) 10.00 mass%

Polyvinyl alcohol aqueous solution (Bw-4) 20.00 mass%

Block isocyanate crosslinking agent (C-1) 0.67 mass%

1.25 mass% of particles

(Silica sol having an average particle diameter of 100 nm, solid content concentration of 40 mass%)

catalyst

0.3 mass% (14 mass% of organic tin compound solid concentration)

0.5 mass% of surfactant

(Silicone system, solid content concentration 10% by mass)

Example 7

The polyester film for polarizer protection was obtained like Example 1 except having changed the mass ratio of polyester resin (A) / polyvinyl alcohol-type resin (B) so that it may become 80/20 by mixing the following ceramics.

43.95 mass% of water

Isopropanol 30.00 mass%

Polyester water dispersion (Aw-1) 13.33 mass%

Polyvinyl alcohol aqueous solution (Bw-4) 10.00 mass%

Block isocyanate crosslinking agent (C-1) 0.67 mass%

1.25 mass% of particles

(Silica sol having an average particle diameter of 100 nm, solid content concentration of 40 mass%)

catalyst

0.3 mass% (14 mass% of organic tin compound solid concentration)

0.5 mass% of surfactant

(Silicone system, solid content concentration 10% by mass)

Example 8

A polyester film for protecting the polarizer was obtained in the same manner as in Example 1 except that the following ceramics were mixed and the mass ratio of the polyester-based resin (A) / polyvinyl alcohol-based resin (B) was changed to 50/50.

33.95 mass% of water

Isopropanol 30.00 mass%

8.33 mass% of polyester water dispersion (Aw-1)

Polyvinyl alcohol aqueous solution (Bw-4) 25.00 mass%

Block isocyanate crosslinking agent (C-1) 0.67 mass%

1.25 mass% of particles

(Silica sol having an average particle diameter of 100 nm, solid content concentration of 40 mass%)

catalyst

0.3 mass% (14 mass% of organic tin compound solid concentration)

0.5 mass% of surfactant

(Silicone system, solid content concentration 10% by mass)

Example 9

The polyester film for polarizer protection was obtained like Example 1 except having changed the composition of the coating liquid as follows.

40.87 mass% of water

Isopropanol 30.00 mass%

Polyester water dispersion (Aw-1) 11.67 mass%

Polyvinyl alcohol aqueous solution (Bw-4) 15.00 mass%

0.71 mass% of melamine type crosslinking agent (C-2)

(Nicarak MX-042 acid and chemical solid concentration 70%)

1.25 mass% of particles

(Silica sol having an average particle diameter of 100 nm, solid content concentration of 40 mass%)

0.5 mass% of surfactant

(Silicone system, solid content concentration 10% by mass)

Example 10

The polarizer protective polyester film was obtained like Example 1 except having changed the polyvinyl alcohol aqueous solution into the aqueous solution (Bw-5) in which the polyvinyl alcohol saponification degree 70 mol% was dissolved.

Example 11

The polarizer protective polyester film was obtained like Example 1 except having changed the polyvinyl alcohol aqueous solution into the aqueous solution (Bw-6) in which the polyvinyl alcohol saponification degree 67 mol% was dissolved.

Example 12

The polyester film for polarizer protection was obtained like Example 1 except having changed the composition of the coating liquid as follows.

40.33 mass% of water

Isopropanol 30.00 mass%

Polyester water dispersion (Aw-1) 11.67 mass%

Polyvinyl alcohol aqueous solution (Bw-2) 15.00 mass%

1.25 mass% of oxazoline type crosslinking agent (C-3)

(Epocross WS-500, manufactured by Japan Catalyst, Solids Concentration 40% by Mass)

1.25 mass% of particles

(Silica sol having an average particle diameter of 100 nm, solid content concentration of 40 mass%)

0.5 mass% of surfactant

(Silicone system, solid content concentration 10% by mass)

Example 13

The polyester film for polarizer protection was obtained like Example 1 except having changed the polyester water dispersion into the water dispersion (Aw-5) in which the polyester resin whose acid value is 10 KOHmg / g was disperse | distributed.

Comparative Example 1

The polyester film for polarizer protection was obtained like Example 1 except having mixed the following ceramics and changing so that mass ratio of polyester-based resin (A) / polyvinyl alcohol-type resin (B) may be 100/0.

50.62 mass% of water

Isopropanol 30.00 mass%

Polyester water dispersion (Aw-1) 16.66 mass%

Block isocyanate crosslinking agent (C-1) 0.67 mass%

1.25 mass% of particles

(Silica sol having an average particle diameter of 100 nm, solid content concentration of 40 mass%)

catalyst

0.3 mass% (14 mass% of organic tin compound solid concentration)

0.5 mass% of surfactant

(Silicone system, solid content concentration 10% by mass)

Comparative Example 2

The polyester film for polarizer protection was obtained like Example 1 except having mixed the following ceramics and changing so that mass ratio of polyester-based resin (A) / polyvinyl alcohol-type resin (B) may be 0/100.

17.28 mass% of water

Isopropanol 30.00 mass%

50.00 mass% of polyvinyl alcohol aqueous solution (Bw-4)

Block isocyanate crosslinking agent (C-1) 0.67 mass%

1.25 mass% of particles

(Silica sol having an average particle diameter of 100 nm, solid content concentration of 40 mass%)

catalyst

0.3 mass% (14 mass% of organic tin compound solid concentration)

0.5 mass% of surfactant

(Silicone system, solid content concentration 10% by mass)

Comparative Example 3

The polyester film for polarizer protection was obtained like Example 1 except having changed the polyester water dispersion into the water dispersion (Aw-4) in which the polyester resin whose acid value is 25KOHmg / g was disperse | distributed.

Comparative Example 4

A polarizer protective polyester film was obtained in the same manner as in Example 1 except that the polyvinyl alcohol aqueous 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

The polarizer protective polyester film was obtained like Example 1 except having changed the polyvinyl alcohol aqueous solution into the aqueous solution (Bw-7) in which the polyvinyl alcohol in which saponification degree is 40 mol% was dissolved.

Comparative Example 6

The polyester film for polarizer protection was obtained like Example 1 except having changed the following ceramics and not changing a crosslinking agent.

41.58 mass% of water

Isopropanol 30.00 mass%

Polyester water dispersion (Aw-1) 11.67 mass%

Polyvinyl alcohol aqueous solution (Bw-4) 15.00 mass%

1.25 mass% of particles

(Silica sol having an average particle diameter of 100 nm, solid content concentration of 40 mass%)

0.5 mass% of surfactant

(Silicone system, solid content concentration 10% by mass)

Reference Example 1

The result of having performed the said adhesive test using the TAC film (The Fujifilm Co., Ltd. make, thickness of 80 micrometers, saponification process completion) as a film for polarizer protection is shown.

The easily adhesive polyester film for polarizer protection of this invention has high adhesiveness with a polarizer and an aqueous adhesive agent. Therefore, it can use suitably as a polarizer protective member.

Claims (5)

As a polyester film which has an easily bonding layer at least on one side,
The easy-adhesive layer contains a polyester resin (A), a polyvinyl alcohol resin (B), and a crosslinking agent (C),
The acid value of the said polyester-based resin (A) is 20 KOHmg / g or less,
The saponification degree of the polyvinyl alcohol-based resin (B) is 60 ~ 85 mol%
Easily-adhesive polyester film for polarizer protection. The method of claim 1,
The easily-adhesive polyester film for polarizer protection which the said polyester resin (A) contains 1-15 mol% of 5-sulfoisophthalic acid components in a dicarboxylic acid component. 3. The method according to claim 1 or 2,
The easily-adhesive polyester film for polarizer protection whose said crosslinking agent (C) is an isocyanate compound or a melamine compound. 4. The method according to any one of claims 1 to 3,
The easily-adhesive polyester film for polarizer protection in which the mass ratio of polyester-based resin (A), polyvinyl alcohol-type resin (B), and a crosslinking agent (C) of the said easily bonding layer satisfy | fills following formula.

As a polarizing plate which has a polarizer protective film on both surfaces of a polarizer,
The polarizing plate whose at least one polarizer protective film is the easily adhesive polyester film for polarizer protection as described in any one of Claims 1-4.