TWI465495B - Easily-adhesive polyester film for protecting polarizer - Google Patents

Description

Easy-adhesive polyester film for polarizer protection

The present invention relates to an easily bondable polyester film for protecting a polarizer from polarizing. More specifically, it relates to an easily bondable polyester film for polarizer protection which is excellent in adhesion to a polarizer.

In the liquid crystal display device, a polarizing plate is disposed on both sides of a glass substrate on which the surface of the liquid crystal panel is formed, based on the image forming method. The polarizing plate is usually configured by a hydrophilic adhesive such as a polyvinyl alcohol-based resin, and a polarizer protective film is bonded to both surfaces of a polarizer composed of a polyvinyl alcohol-based film and a dichroic material such as iodine. As a protective film for polarizer protection, a triethylenesulfonated cellulose film has been conventionally used in consideration of optical properties and transparency.

However, the durability of triethylenesulfonyl cellulose is not sufficient. If a polarizing plate using a triethylenesulfonated cellulose film as a polarizer protective film is used under high temperature or high humidity, polarized light and color are polarized equally. The situation where the board performance is degraded. In addition, in order to reduce the thickness of the display in recent years, it is also required to reduce the thickness of the polarizing plate. However, the triacetyl cellulose film has a limit in thin film formation from the viewpoint of maintaining moisture resistance characteristics. Therefore, a polyester film has been proposed as a polarizer protective film having durability and moisture resistance (see Patent Documents 1 to 5).

The triethylenesulfonated cellulose film used as a polarizer protective film is subjected to an alkaline treatment or the like on the surface, and has a very high affinity with a hydrophilic adhesive. Therefore, the protective film composed of the triethylenesulfonated cellulose film and the polarizer coated with the hydrophilic adhesive have extremely high adhesion. However, the adhesiveness of the polyester film and the hydrophilic adhesive is insufficient, and in particular, in the case of a polyester film having an alignment property by the stretching treatment, this tendency is more remarkable. Therefore, in Patent Documents 1 to 3 and 5, in order to enhance the adhesion of a polarizer or a hydrophilic adhesive applied to a polarizer, it is proposed to provide an easy-adhesion layer on the polyester film.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. Hei 8-271733

Patent Document 2: Japanese Laid-Open Patent Publication No. 8-271734

Patent Document 3: Japanese Laid-Open Patent Publication No. 2009-157361

Patent Document 4: Japanese Laid-Open Patent Publication No. 2010-277028

Patent Document 5: Japanese Laid-Open Patent Publication No. 2011-8170

The tendency of the polyester film to have low affinity for water is particularly remarkable as a polyester film having an aromatic dicarboxylic acid as a dicarboxylic acid component. Further, the polyester film having crystal orientation by stretching has a lower affinity with water. On the other hand, the polarizer or the adhesive applied to the polarizer is mainly composed of a polyvinyl alcohol-based resin and has high hydrophilicity. Due to such a difference in properties, the affinity between the polyester film and the polarizer or the aforementioned adhesive is low, and it is difficult to make the two firmly followed. Therefore, even in the polyester film having an easy-adhesion layer disclosed in Patent Documents 1 to 3 and 5, sufficient adhesion cannot be obtained as compared with the triethylenesulfonated cellulose film. Therefore, when a polarizing plate using a conventional polyester film as a protective film is used as a display member for a long period of time, bubbling or peeling occurs between the protective film/polarizer, and the amount of moisture in the polarizer changes. The polarization characteristics are lowered, and the visibility such as whitening is deteriorated.

In view of the above, an object of the present invention is to provide a polyester film having a means for firmly adhering a polyvinyl alcohol-based resin layer such as a polyester film and a polarizer or an adhesive applied to a polarizer. for purpose.

In order to solve the above-mentioned problems, the inventors of the present invention have conducted intensive research and review, and have obtained a polyester resin having a high affinity with a polyester film and a poly-polymer between the polyester film and the polyvinyl alcohol-based resin layer. A concept of a layer of a polyvinyl alcohol-based resin having a high affinity for a vinyl alcohol-based resin layer and a crosslinking agent. However, the present inventors have found that when only these components are combined, the function of bringing the polyester film and the polyvinyl alcohol-based resin layer into close contact with each other cannot be sufficiently exhibited. Therefore, the inventors of the present invention have repeatedly conducted research on the day and night, and found that in the above concept, a polyester resin having a certain acid value is used as the polyester resin, and a polyvinyl alcohol-based resin having a certain saponification value is used. The polyvinyl alcohol-based resin can effectively exhibit the function of each of the components and the resin layer having high affinity.

As a result of further research based on the above findings, the present inventors have found that a polyvinyl alcohol-based resin such as a polyester film and a polarizer or an adhesive can be used by using a crosslinking agent having high reactivity with a hydroxyl group. The layer is more firmly followed. Based on these findings, the inventors of the present invention have further reviewed and improved the present invention.

Representatives of the present invention are disclosed, for example, below.

According to a first aspect of the invention, there is provided an easy-adhesive polyester film for protecting a polarizer, which has an easy-adhesion layer on at least one side, and the easy-adhesion layer contains a polyester resin (A) and a polyvinyl alcohol resin (B) And the crosslinking agent (C); the polyester resin (A) has an acid value of 20 KOH mg/g or less; and the polyvinyl alcohol-based resin (B) has a saponification value of 60 to 85 mol%.

According to a second aspect of the invention, the polyester resin (A) contains 1 to 15 mol% of a 5-sulfonic acid isophthalic acid photo-protecting easy-bonding polyester film in the dicarboxylic acid component.

According to a third aspect of the invention, the crosslinking agent (C) is an easily bondable polyester film for protecting a polarizer of an isocyanate compound or a melamine compound.

According to a fourth aspect of the invention, in the easy-adhesion layer for the photoconductor-protecting easy-adhesive polyester film, the mass ratio of the polyester resin (A), the polyvinyl alcohol resin (B), and the crosslinking agent (C) is satisfied. Easy-adhesive polyester film for polarizer protection of the following formula, 0.8≦(A)/(B)≦5

0.2 ≦ ((A) + (B)) / (C) ≦ 50.

According to a fifth aspect of the invention, there is provided a polarizing plate comprising a polarizer protective film on both sides of a polarizer; and at least one of the polarizer protective films is the above-mentioned photoconductive protective easy-adhesive polyester film.

The adhesive film for protecting the polarizer for the present invention and the polarizing film or the representative polyvinyl alcohol-based resin layer as an adhesive applied thereto are excellent in adhesion. Therefore, the polyester film of the present invention can be suitably used as a protective film for a polarizer. By using such a polyester film of the present invention as a protective film for a polarizer, a polarizing plate excellent in durability and water resistance can be produced at a lower cost. Moreover, since the polarizing plate of the present invention is excellent in durability, it can be made thinner than ever. Therefore, by using the polarizing plate of the present invention, the liquid crystal display can be made thinner.

[Formation for implementing the invention]

(Polyester film)

The polyester film used as the substrate in the present invention is mainly a film composed of a polyester resin. Here, the "film mainly composed of a polyester resin" means a film formed of a resin composition containing 50% by mass or more of a polyester resin, and when blended with other polymers, it means polyester. When the resin is copolymerized with another monomer in an amount of 50% by mass or more, it means that the polyester structural unit is contained in an amount of 50 mol% or more. The polyester film is preferably contained in an amount of 90% by mass or more, preferably 95% by mass or more, and more preferably 100% by mass.

The material of the polyester resin is not particularly limited, and a copolymer formed by polycondensation of a dicarboxylic acid component and a diol component, or a blended resin thereof may be used. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 2,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and 1,4-naphthalene dicarboxylic acid. 1,5-naphthalene dicarboxylic acid, diphenyl carboxylic acid, diphenoxy ethane dicarboxylic acid, diphenyl hydrazine carboxylic acid, hydrazine dicarboxylic acid, 1,3-cyclopentane dicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3 ,3-diethyl succinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipate, trimethyl adipate, pimelic acid, bismuth Acid, dimer acid, sebacic acid, suberic acid, dodecanedioic acid, and the like.

Examples of the diol component constituting the polyester resin include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and hydrazine. Glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-bis(4-hydroxyphenyl)propane, bis (4) -Hydroxyphenyl)anthracene and the like.

One type or two or more types of the dicarboxylic acid component and the diol component which are constituting the polyester resin can be used. Further, other acid components such as trimellitic acid or other hydroxyl group components such as trimethylolpropane may be appropriately added.

Specifically, examples of the polyester resin include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Among them, In view of the balance between physical properties and cost, ethylene terephthalate is preferred. Further, in order to control optical characteristics such as polarizability, it is preferred to contain other copolymerization components and/or other polymers. In view of controlling the optical properties of the polyester film, a preferred copolymerization component is, for example, diethylene glycol or a copolymerization component having a norbornene in a side chain.

The polyester film of the present invention is used as a protective film for a polarizer, and therefore has high transparency. The transparency of the polyester film for polarizer protection of the present invention preferably has a total light transmittance of 85% or more, more preferably 87% or more, particularly preferably 88% or more, and still more preferably 89% or more. Good is over 90%. Further, the haze is preferably 3% or less, more preferably 2.5% or less, still more preferably 2% or less, and particularly preferably 1.5% or less. The total light transmittance of the polyester film can be measured, for example, according to the method described in the examples below.

In order to improve the smoothness of the polyester film, the usability of winding properties, etc., there are cases where inert particles are contained in the film, but in order to maintain high transparency, the content of inert particles in the film is as small as possible. Preferably. Therefore, it is preferable to form a multilayer structure containing particles only in the surface layer of the film, or substantially no particles in the film, and to contain fine particles only in the easy-adhesion layer laminated on at least one surface of the polyester film.

In addition, the term "substantially no particles" means, for example, 50 ppm or less, preferably 10 ppm or less, in the case of quantitative analysis of elements derived from particles by fluorescent X-ray analysis. To detect the content below the limit. The reason is that even if the particles are not actively added to the base film, the contaminated component from the foreign matter or the raw material resin or the contaminant attached to the line or the film manufacturing step can be peeled off and mixed into the film. In the situation.

Further, when the base film is formed into a multilayer structure, the inner layer does not substantially contain inert particles, and the outermost layer contains two kinds of three layers of inert particles, and it is preferable to achieve both transparency and workability.

The thickness of the film in the present invention is not particularly limited. When the thickness of the polarizing plate is reduced in order to reduce the thickness of the display, the thickness of the film is preferably 200 μm or less, and more preferably 100 μm or less. On the other hand, in order to maintain the mechanical strength as a protective film, the thickness of the film is preferably 10 μm or more, more preferably 12 μm or more, and still more preferably 20 μm or more.

The polyester film used as the substrate may be a single layer or a layer of two or more layers. Further, as long as it is within the range in which the effects of the present invention can be attained, various additives may be contained in the film as needed. Examples of the additive include an antioxidant, a light stabilizer, an antigelling agent, an organic wetting agent, an antistatic agent, an ultraviolet absorber, a surfactant, and the like. When the film has a laminated structure, it is preferred to contain an additive depending on the function of each layer as needed. For example, in order to prevent photodegradation of the polarizer, it is preferable to add an ultraviolet absorber or the like to the inner layer.

The polyester film can be produced, for example, by melt-extruding the above-mentioned polyester resin into a film shape, cooling it and solidifying it in a casting drum to form a film. The polyester film of the present invention can be used in any of the non-stretched film and the stretched film, and is preferably an extended film from the viewpoint of durability of mechanical strength and chemical resistance. When the polyester film is a stretched film, the stretching method is not particularly limited, and a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a vertical and horizontal sequential biaxial stretching method, a vertical and horizontal simultaneous biaxial stretching method, or the like can be employed.

(easy to layer)

The polyester film of the present invention has an easy-adhesion layer laminated on at least one surface thereof in order to improve the adhesion between the polarizer and the polyvinyl alcohol-based resin layer such as a water-based adhesive provided on one or both sides of the polarizer. The easy-adhesive layer is composed of a polyester resin (A) having an acid value of 20 KOH mg/g or less, a polyvinyl alcohol-based resin (B) having a saponification value of 60 to 85 mol%, and a crosslinking agent (C). ) formed by the resin composition. The easy-adhesive layer may be provided on both sides of the polyester film, or may be provided only on one side of the polyester film, and the other side may be provided with a resin coating layer of another kind.

The following theory is not intended to be used as a limitation, and it is considered that a specific polyester resin (A) having a saponification value of 20 KOH mg/g or less and a specific polyvinyl alcohol resin having a saponification value of 60 to 85 mol%. (B) In combination with the crosslinking agent (C), the polyester resin and the polyvinyl alcohol resin form respective domain units in the easy-adhesion layer, and form a phase separation structure generally called "island structure". . By the separation structure which is the unit of such a region, the adhesion between the region composed of the polyester resin and the polyester film, and the adhesion between the region composed of the polyvinyl alcohol resin and the polyvinyl alcohol resin layer. The functions of the two can be properly compromised without jeopardizing each other. Further, it is considered that the crosslinking agent (C) promotes and maintains the formation of the structure of the region by crosslinking/aggregating the polyvinyl alcohol-based resin (B).

Hereinafter, the respective components of the easy-to-back layer will be described in detail.

(Polyester resin (A))

The polyester 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 a dicarboxylic acid component and a diol component can be used as the substrate. Polyester film material. In view of the improvement of the adhesion to the polyester film substrate, it is preferred to use a dicarboxylic acid component having the same or similar structure/properties as the dicarboxylic acid component in the polyester film as the substrate. A dicarboxylic acid component of the polyester resin (A). Therefore, for example, when an aromatic dicarboxylic acid is used as the dicarboxylic acid component of the polyester film, it is preferred to use an aromatic dicarboxylic acid as the dicarboxylic acid component of the polyester resin (A). The aromatic dicarboxylic acid component is preferably terephthalic acid or isophthalic acid. Other aromatic dicarboxylic acids may be added to copolymerize the entire dicarboxylic acid component in an amount of 10 mol% or less.

Further, the diol component of the polyester resin (A) is preferably composed of ethylene glycol and a branched diol as a constituent component. I believe that by having a branched structure, it is possible to relax the stress in the easy-adhesion layer, and the adhesion can be suitably exhibited. The diol component of the above branched group may, for example, be 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, or 2-methyl-2-butyl group. -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- Propylene glycol and the like.

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

The polyester resin (A) used in the present invention is preferably a water-soluble or water-dispersible resin in consideration of compatibility with the polyvinyl alcohol-based resin (B). In order to make the polyester resin water-soluble or water-dispersible, it is preferred to copolymerize a compound containing a hydrophilic group such as a sulfonate group or a carboxylate group. In view of the fact that the hydrophilicity of the polyester resin (A) is kept low, and the hydrophilicity is imparted while controlling the reactivity with the crosslinking agent, a dicarboxylic acid component having a sulfonate group is preferred. . Examples of the dicarboxylic acid component having a sulfonate group include a sulfonic acid terephthalic acid, a 5-sulfonic acid isophthalic acid, and a 4-sulfonic acid naphthalene isophthalic acid-2,7-dicarboxylic acid. And 5-(4-sulfophenoxy)isophthalic acid or an alkali metal salt thereof, among which 5-sulfonic acid isophthalic acid is preferred. The dicarboxylic acid component having a sulfonate group is preferably 1 to 15 mol%, more preferably 1.5 to 12 mol%, and particularly preferably 2 to 10 mol% of the dicarboxylic acid component of the polyester resin (A). ear%. When the dicarboxylic acid component having a sulfonate group is at least the above lower limit, it is preferred to be water-soluble or water-dispersed in the polyester resin. Further, when the dicarboxylic acid component having a sulfonate group is at most the above upper limit, the adhesion to the polyester film substrate is preferred.

The carboxylic acid group of the reactive group with the crosslinking agent (C) in the polyester resin (A) is less preferred. It is believed that by reducing the carboxyl group reactive with the crosslinking agent, the reactivity with the crosslinking agent can be reduced, and as a result, it is not completely mixed with the polyvinyl alcohol-based resin, and can be maintained by cross-linking. The structure of the region formed by the polyvinyl alcohol resin. From this point of view, the acid value of the polyester resin (A) is preferably 20 KOH mg/g, preferably 15 KOH mg/g or less, more preferably 10 KOH mg/g or less, and particularly preferably 8 KOH mg/g. More preferably, it is 5 KOH mg/g or less. The acid value of the polyester resin (A) can be theoretically determined from the results of component analysis by a titration method or NMR described later.

In order to control the acid value of the polyester resin (A) in the above range, it is preferred to reduce the introduction amount of the carboxylate group for water-solubilization or water-dispersion, and to use hydrophilicity other than the carboxylate group. The base is reduced in the concentration of the carboxylic acid terminal group of the polyester resin. The method of lowering the concentration of the carboxylic acid terminal group of the polyester resin is preferably a polyester resin having a terminal group modified with a terminal group of a carboxylic acid, and a polyester having a larger number average molecular weight of the polyester resin. Resin. Therefore, the number average molecular weight of the polyester resin (A) is preferably 5,000 or more, more preferably 6,000 or more, and still more preferably 10,000 or more. Moreover, it is preferable that the component of the polyester resin (A) is a content which reduces the acid component which has three or more carboxyl groups.

The glass transition temperature of the polyester resin (A) is not particularly limited, but is preferably 20 to 90 ° C, more preferably 30 to 80 ° C. When the glass transition temperature is at least the above lower limit, it is preferable for the anti-blocking property, and if the glass transition temperature is not more than the above upper limit, it is preferable for the adhesion to the polyester film substrate.

The content of the polyester resin (A) in the easy-adhesion layer is preferably 40% by mass or more and 90% by mass or less, more preferably 45% by mass or more and 85% by mass or less, and particularly preferably 50% by mass or more and 80% by mass or less. the following. When the content of the polyester resin (A) is at least the above lower limit, it is preferably in adhesion to the polyester film substrate, and when it is at most the above upper limit, it is a polyvinyl alcohol such as a polarizer or a hydrophilic adhesive. The adhesion between the resins is preferred.

(polyvinyl alcohol resin (B))

The polyvinyl alcohol-based resin is not particularly limited, and examples thereof include polyvinyl alcohol obtained by saponifying polyvinyl acetate, derivatives thereof, and saponification of a copolymer of a monomer copolymerizable with vinyl acetate. A modified polyvinyl alcohol obtained by acetalizing, urethane, etherifying, grafting, or phosphating a polyvinyl alcohol. Examples of the monomer include unsaturated polymers such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, and (meth)acrylic acid, and esters thereof; and ethylene, propylene, and the like. Α-olefin, (meth)allylsulfonic acid (sodium), sodium sulfonate (single alkyl maleate), sodium disulfonate alkyl maleate, N-methylol Acrylamide, acrylamide alkylsulfonate alkali salt, N-vinylpyrrolidone, N-vinylpyrrolidone derivative, and the like. These polyvinyl alcohol-based resins may be used alone or in combination of two or more.

The polyvinyl alcohol-based resin (B) used in the present invention may, for example, be a vinyl alcohol-vinyl acetate copolymer, a vinyl alcohol-vinyl butyral copolymer or an ethylene-vinyl alcohol copolymer. It is a vinyl alcohol-vinyl acetate copolymer or an ethylene-vinyl alcohol copolymer. The degree of polymerization of the polyvinyl alcohol-based resin (B) is not particularly limited, and the degree of polymerization of the coating liquid is preferably 3,000 or less.

The copolymerization ratio of vinyl alcohol can be expressed by a saponification value. The saponification value of the polyvinyl alcohol-based 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, still more preferably 68 mol%. The above 80 mol% or less, particularly preferably 70 mol% or more and 80 mol% or less, 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 saponification value of the polyvinyl alcohol-based resin (B) is at least the above lower limit, the cross-linking structure can be more preferably formed with the crosslinking agent (C). In addition, when the saponification value of the polyvinyl alcohol-based resin (B) is not more than the above upper limit (or not), the polyester resin (A) can exhibit compatibility more preferably. The saponification value of the vinyl alcohol-based resin can be determined by the amount of alkali consumption required for hydrolysis of a copolymerization unit such as vinyl acetate or by composition analysis by NMR.

The content of the polyvinyl alcohol-based 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 particularly preferably 20% by mass or more and 50% by mass or less. the following. When the content of the polyvinyl alcohol-based resin (B) is at least the above lower limit, the adhesion between the polarizer, the adhesive, and the like and the polyvinyl alcohol-based resin layer is preferable, and if it is at most the above upper limit, the polyester is The adhesion between the film substrates is preferred.

(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 a melamine system, an isocyanate system, a carbodiimide system, an oxazoline system, and a ring. A compound such as an oxygen system. The melamine-based, isocyanate-based, methane diimine-based, or oxazoline-based compound is preferable in terms of the stability of the coating liquid. Further, the crosslinking agent is preferably a melamine-based compound or an isocyanate-based compound which is preferably cross-linked with a hydroxyl group of the polyvinyl alcohol-based resin (B). The reason for this is considered to be that the melamine-based compound or the isocyanate-based compound reacts with a hydroxyl group with respect to the methane diimine-based crosslinking agent, and can react with a hydroxyl group-containing functional group. The alcohol-based resin (B) is preferably formed in a cross-linked structure. In particular, it is preferable to use an isocyanate-based compound in view of the fact that the hydroxyl group of the polyvinyl alcohol-based resin is preferably subjected to a crosslinking reaction and is excellent in transparency. Further, in order to promote the crosslinking reaction, a catalyst or the like may be appropriately used as needed.

The isocyanate compound may be a low molecular or high molecular diisocyanate or a trivalent or higher polyisocyanate. For example, the isocyanate compound may, for example, be 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2, 2'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 1,4-naphthalene diisocyanate, phenyl diisocyanate, tetramethyl decyl diisocyanate, 4,4'-diphenyl ether diisocyanate , 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4, An aromatic diisocyanate such as 4'-diisocyanate, 4,4'-diphenylpropane diisocyanate or 3,3'-dimethoxydiphenyl-4,4'-diisocyanate; An aromatic aliphatic diisocyanate such as an isocyanate; an alicyclic diisocyanate such as isophorone diisocyanate or 4,4-dicyclohexylmethane diisocyanate or 1,3-bis(isocyanatemethyl)cyclohexane; An aliphatic diisocyanate such as hexamethylene diisocyanate or 2,2,4-trimethylhexamethylene diisocyanate; and the amount of the isocyanate compoundFurther, examples thereof include an amount of the isocyanate compound which is excessively mixed with ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine or the like. A compound having an isocyanate group at a polymer terminal obtained by reacting a low molecular weight active hydrogen compound or a polyester polyol; a polyether polyol or a polymer active hydrogen compound such as a polyimine.

The melamine compound may be a melamine compound substituted with a substituent -(CH2)nOR (wherein n is an integer of 1-3, and R is an alkyl group having 1 to 4 carbon atoms), and R in the above formula is preferred. Is a methyl group. The number of the above substituents in one melamine structure is preferably from 3 to 6. Specific examples of the melamine compound include M-3, MK, M-6, M-100, MC, etc. of the Sumitex Resin series manufactured by Sumitomo Chemical Co., Ltd. or methylated melamine resin MW-22 manufactured by Sanwa Chemical Co., Ltd. , MX-706, MX-042, etc.

The crosslinking agent (C) used in the present invention is preferably a blocked isocyanate compound. By adding a blocked isocyanate compound, the temporal stability of the coating liquid can be more preferably improved.

The blocked isocyanate compound can be prepared by subjecting the above isocyanate compound to a blocking agent by an addition reaction in a conventional manner. Examples of the isocyanate blocking agent include phenols such as phenol, cresol, xylenol, resorcin, nitrophenol, and chlorophenol; thiophenols such as thiophenol and methylthiophenol; Anthraquinone such as methyl ethyl ketone oxime or cyclohexanone oxime; alcohols such as methanol, ethanol, propanol and butanol; halogen-substituted alcohols such as chlorohydrin and 1,3-dichloro-2-propanol; a third-order alcohol such as an alcohol or a tertiary heptanol; an indoleamine such as ε-caprolactam, δ-valeroinamide, γ-butyrolactam or β-propionamide; aromatic Amines; quinone imines; active methylene compounds such as acetoacetone, acetamidine acetate, ethyl malonate; thiols; imines; ureas; diaryl compounds; hydrogen sulfite Sodium and so on.

The content of the crosslinking agent (C) is preferably 2% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, and particularly preferably 8% by mass or more and 30% by mass or less in the easy-adhesion layer. . When the content of the crosslinking agent (C) is at least the above lower limit, the polyvinyl alcohol-based resin is preferably crosslinked, and when it is at most the above upper limit, the effect of the adhesiveness of the adhesive resin is preferably exhibited.

The blending ratio (A)/(B) of the polyester resin (A) and the polyvinyl alcohol resin (B) is preferably from 0.8 to 5, more preferably from 1 to 4, particularly preferably from 2 to 2 by mass. 4, especially good 2.5~3.5. When (A)/(B) is at least the above lower limit, adhesion to the polyester film substrate is preferable, and when it is at most the above upper limit, adhesion to a polyvinyl alcohol-based resin layer such as a polarizer or an adhesive is used. Preferably.

The blending ratio ((A) + (B)) / (C) of the polyester resin (A) and the polyvinyl alcohol resin (B) to the crosslinking agent (C) is preferably 2 to 50 by mass ratio. More preferably 5~40, especially 8~30. ((A)+(B))/(C), if it is more than the above lower limit, the adhesive effect by the binder resin component can be preferably exhibited, and if it is less than or equal to the above upper limit, it is caused by phase separation. The subsequent effect is better.

The easy-adhesive layer of the present invention exhibits high adhesion to a polarizer or an aqueous binder (particularly a polyvinyl alcohol-based polarizer or an aqueous binder) equivalent to triethyl fluorenyl cellulose by using the above composition. . Specifically, the residual area after the primary peeling of the aqueous adhesive by the adhesion test described later is preferably 90% or more, more preferably 95% or more, and particularly preferably 100%, after 5 consecutive peelings. The remaining area is preferably 75% or more, more preferably 85% or more, and particularly preferably 95% or more, and the residual area after 10 consecutive peeling is preferably 50% or more, more preferably 80% or more, and particularly preferably 90%. More preferably, the above is more than 93%, and particularly preferably 95% or more.

(additive)

In the easy-adhesion layer of the present invention, well-known additives such as a surfactant, an antioxidant, a catalyst, a heat stabilizer, a weathering stabilizer, and an ultraviolet absorber may be added to the extent that the effects of the present invention are not impaired. , organic slip agents, pigments, dyes, organic or inorganic particles, antistatic agents, nucleating agents, etc.

In the present invention, in order to further improve the anti-adhesion property of the easy-adhesion layer, it is preferred to add particles to the easy-adhesion layer. In the present invention, the particles contained in the easy-adhesion layer may, for example, be titanium dioxide, barium sulfate, calcium carbonate, calcium sulfate, barium oxide, aluminum oxide, talc, kaolin, clay, or the like, or a mixture thereof, or the like. Other general inorganic particles such as calcium phosphate, mica, hectorite, zirconium, tungsten oxide, lithium fluoride, calcium fluoride, etc., or styrene, acrylic, melamine, benzoguana An organic polymer-based particle such as an amine or a siloxane.

The average particle diameter of the inert particles in the easy-adhesion layer (average particle diameter based on the number of SEMs, the same applies hereinafter) is preferably 0.04 to 2.0 μm, more preferably 0.1 to 1.0 μm, and the average particle diameter of the inert particles is When the thickness is less than 0.04 μm, the formation of irregularities on the surface of the film may be insufficient, and the usability such as film smoothness and take-up property may be lowered, and the workability at the time of bonding may be lowered. On the other hand, if it exceeds 2.0 μm, the particles may fall off in the solution, which is not preferable. The concentration of the particles in the easy-adhesion layer is preferably from 1 to 20% by mass, more preferably from 5 to 15% by mass, based on the solid content.

The thickness of the easy-adhesion layer in the present invention can be appropriately set in the range of 0.001 to 2.00 μm, and is preferably in the range of 0.01 to 1.00 μm, more preferably 0.02 to 0.80 μm, and particularly preferably 0.05 in order to achieve both workability and adhesion. ~0.50μm. If the thickness of the easily-adherent layer is less than 0.01 μm, the adhesion may be insufficient. If the thickness of the easily-adhesive layer exceeds 2.00 μm, adhesion may occur.

(Manufacture of easy-adhesive polyester film for polarizer protection)

In the method for producing an easily-adhesive polyester film for polarizer protection of the present invention, a polyethylene terephthalate (hereinafter abbreviated as PET) film is exemplified, but it is of course not limited thereto.

After the PET resin is sufficiently vacuum-dried, it is supplied to an extruder, and a molten PET resin of about 280 ° C is melt-extruded from a T-die to a rotary cooling roll to form a sheet, which is cooled and solidified by an electrostatic method. An unstretched PET sheet was obtained. The unstretched PET sheet may be composed of a single layer or may be formed by a co-extrusion method.

The obtained unstretched PET sheet was subjected to uniaxial stretching or biaxial stretching to crystallize it. For example, in the case of biaxial stretching, a roller which is heated to 80 to 120 ° C is extended in the longitudinal direction by 2.5 to 5.0 times to obtain a uniaxially stretched PET film, and then the end portion of the film is sandwiched by a clip to be introduced into the heating. The hot air area of 80 to 180 ° C extends to 2.5 to 5.0 times in the width direction. Moreover, in the case of uniaxial stretching, it is extended to 2.5 to 5.0 times in the tenter. After the extension, the film is further guided to a heat treatment zone of 140 to 240 ° C, and heat treatment is performed for 1 to 60 seconds to complete the crystal alignment.

The easy-adhesion layer can be provided after the film is manufactured, or in the manufacturing step. In terms of productivity considerations, it is particularly preferred to apply a coating liquid at any stage of the film manufacturing step, that is, to at least one side of the unstretched or uniaxially stretched PET film to form an easy-adhesion layer.

The method for applying the coating liquid onto the PET film can be any known method. For example, a reverse roll coating method, a gravure coating method, an anastomotic coating method, a die coating method, a roll coating method, a spray coating method, a knife coating method, a wire bar coating method, a tube coating method, a dip coating method, and a curtain Curtain coating method, etc. These methods can be applied individually or in combination.

In the present invention, it is preferred that the thickness of the finally obtainable adhesive layer is 0.03 to 0.20 g/m ² . When it is 0.03 g/m ² or less, the adhesion is lowered, and if it is thicker than 0.20 g/m ² , the adhesion and smoothness are lowered, which is not preferable.

(polarizer)

The polarizing plate of the present invention is a polarizing plate having a polarizer protective film on both sides of a polarizer. Preferably, at least one of the polarizer protective films is the above-mentioned easily-bondable polyester film for protecting a polarizer. The other polarizer protective film may be the easy-contact polyester film for polarizer protection of the present invention, and preferably has no birefringence represented by a triethylenesulfonated cellulose film or an acrylic resin film or a decene-based film. Film.

The polarizer may, for example, be a dichroic material such as iodine contained in a polyvinyl alcohol-based film. The polarizer protective film can be directly bonded to the polarizer or adhered through the adhesive layer to improve the adhesion, preferably through the adhesive. At this time, the easy-adhesion layer of the present invention is preferably disposed on the polarizing surface or the adhesive layer. The preferred polarizer for the polyester film to be used in the present invention is, for example, uniaxially stretched in an aqueous solution of boric acid by dyeing/absorbing the polyvinyl alcohol-based film with iodine or a dichroic material. The polarizer obtained by washing/drying while being kept in an extended state. The magnification of the uniaxial extension is usually about 4 to 8 times. The polyvinyl alcohol-based film is preferably polyvinyl alcohol, and "Kuraray Vinylon" (manufactured by Kuraray Co., Ltd.), "Tohcello Vinylon" (manufactured by Tohcello Co., Ltd.), and "Nisshin Vinylon" (made by Nippon Synthetic Chemical Co., Ltd.) can be used. ) and other commercial products. Examples of the dichroic material include iodine, a disazo compound, polymethine, and the like.

The adhesive applied to the polarizer is preferably a water-based one, that is, preferably, the adhesive component is dissolved in water or dispersed in water. For example, a polyvinyl alcohol-based resin, a urethane resin or the like is used as a main component, and in order to improve adhesion, a composition such as an isocyanate compound or an epoxy compound may be blended as needed. The thickness of the subsequent layer is preferably 10 μm or less, more preferably 5 μm or less, and still more preferably 3 μm or less.

When a polyvinyl alcohol-based resin is used as a main component of the adhesive, a partially saponified polyvinyl alcohol or a fully saponified polyvinyl alcohol may be used, and a carboxy-modified polyvinyl alcohol or an ethylene-ethyl fluorene-modified polyvinyl alcohol may be used. A modified polyvinyl alcohol-based resin such as a methylol-modified polyvinyl alcohol or an amine-modified polyvinyl alcohol. The concentration of the polyvinyl alcohol-based resin in the subsequent agent is preferably from 1 to 10% by mass, more preferably from 2 to 7% by mass.

[Examples]

Next, the present invention will be described in detail by way of Examples, Comparative Examples and Reference Examples. However, the present invention is of course not limited to the following examples. Further, the evaluation method used in the present invention is as follows.

(1) Glass transition temperature

According to JIS K7121, using a differential scanning calorimeter (manufactured by Seiko Instruments, DSC6200), 10 mg of the resin sample was heated at a temperature of 25 to 300 ° C at 20 ° C / min to obtain a glass transition temperature from the DSC curve. It is the glass transition temperature.

(2) number average molecular weight

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

(3) Resin composition

The resin was dissolved in heavy chloroform, and subjected to ¹ H-NMR analysis using a nuclear magnetic resonance analyzer (NMR) GEMINI-200 manufactured by VARIAN Co., Ltd., and the molar ratio of each composition was determined from the integral ratio thereof.

(4) Acid value

1 g (solid content) of the sample was dissolved in 30 ml of chloroform or dimethylformamide, and phenolphthalein was used as an indicator, and titrated with a 0.1 N sodium hydroxide ethanol solution to obtain a carboxyl group neutralized per 1 g of the sample. The amount of KOH (mg) necessary.

(5) Saponification value

According to JIS-K6726, the residual acetic acid group (mol%) of the polyvinyl alcohol resin was quantified with sodium hydroxide, and the value was used as the saponification value (% by mole). The same sample was measured 3 times, and the average value thereof was used as a saponification value (% by mole).

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

The total light transmittance of the polyester film for polarizer protection was measured by a haze meter (manufactured by Nippon Denshoku Co., Ltd., NDH2000) in accordance with JIS K 7105.

(7) Haze of polyester film for polarizer protection

The haze of the polarizer-protected polyester film was measured by a haze meter (manufactured by Nippon Denshoku Co., Ltd., NDH2000) in accordance with JIS K 7136.

(8) PVA adhesion

A polyvinyl alcohol aqueous solution (PVA117 manufactured by Kuraray) having a solid content concentration of 5% by mass was applied to the polyester film for polarizer protection by a wire bar so that the thickness of the dried polyvinyl alcohol resin layer was 2 μm. It is easy to adhere to the surface of the layer and dry at 70 ° C for 5 minutes. A polyvinyl alcohol aqueous solution is used by adding a red dye which can be easily determined. The film to be evaluated was placed on the opposite side of the surface on which the polyvinyl alcohol resin layer was formed on the laminated film to be evaluated, and bonded to a glass plate having a thickness of 5 mm to which the double-faced tape was bonded. Next, a dicing guide having a gap interval of 2 mm was cut into 100 square-shaped cuts penetrating the polyvinyl alcohol resin layer to the base film. Then, it was adhered to a checkered cut surface by an adhesive tape (Cellophane tape (registered trademark) CT-24, manufactured by NICHIBAN Co., Ltd., 24 mm width). The air remaining in the interface at the time of bonding was squeezed with an eraser so that it was completely adhered, and the operation of pulling the adhesive tape vertically away was performed once, five times, and ten times. The number of squares in which the calculated polyvinyl alcohol resin layer was not peeled off was used as the PVA adhesion. That is, when the PVA layer was not completely peeled off, the PVA adhesion rate was set to 100, and when the PVA layer was completely peeled off, the PVA adhesion rate was set to zero. In addition, the partial peeling in one square is also counted as the number of peeling.

(polymerization of polyester resin)

In a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux cooler, 194.2 parts by mass of dimethyl terephthalate, 184.5 parts by mass of dimethyl isophthalate, and 14.8 mass were fed. Parts of dimethyl-5-sodium sulfonate isophthalate, 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, for 4 hours The transesterification reaction is carried out at a temperature of from 160 ° C to 220 ° C. Subsequently, the temperature was raised to 255 ° C, and the reaction system was gradually depressurized, and then reacted under reduced pressure of 30 Pa for 1 hour and 30 minutes to obtain a copolymerized polyester resin (A-1). The obtained copolymerized polyester resin (A-1) was light yellow transparent. The reducing viscosity of the copolymerized polyester resin (A-1) was measured and found to be 0.70 dl/g. The glass transition temperature obtained by DSC was 40 °C.

In the same manner, a copolymerized polyester resin (A-2) to (A-5) of another composition was obtained. The composition (monomer ratio) measured by ¹ H-NMR and the other characteristics of the copolymerized polyester resin are shown in Table 1.

(polyester water dispersion adjustment)

In a reactor equipped with a stirrer, a thermometer, and a reflux device, 30 parts by mass of a polyester resin (A-1) and 15 parts by mass of ethylene glycol n-butyl ether were fed, and the mixture was heated and stirred at 110 ° C to dissolve the resin. . After the resin was completely dissolved, 55 parts by mass of water was slowly added to the polyester solution while stirring. After the addition, the liquid was cooled to room temperature with stirring, and a milky white polyester aqueous dispersion (Aw-1) having a solid content of 30% by mass was obtained. In the same manner, a polyester resin (A-2) to (A-5) was used instead of the polyester resin (A-1) to prepare an aqueous dispersion, which was respectively used as a polyester aqueous dispersion (Aw-2)~(Aw -5).

(Adjustment of polyvinyl alcohol aqueous solution)

In a container equipped with a stirrer and a thermometer, 90 parts by mass of water was fed, and 10 parts by mass of a polyvinyl alcohol resin (manufactured by Kuraray) (B-1) having a polymerization degree of 500 was gradually added thereto with stirring. After the addition, the mixture was heated while stirring to 95 ° C to dissolve the resin. After the dissolution, the mixture was cooled to room temperature while stirring to obtain a polyvinyl alcohol aqueous solution (Bw-1) having a solid content of 10% by mass. In the same way, polyvinyl alcohol resin (B-2)~(B-7) is used instead of polyvinyl alcohol resin (B-1) to form an aqueous solution, which is (Bw-2)~(Bw-7). . The saponification values of the polyvinyl alcohol resins (B-1) to (B-7) are shown in Table 2.

(polymerization of block polyisocyanate crosslinker)

In a flask equipped with a stirrer, a thermometer, and a reflux cooling tube, 100 parts by mass of a polyisocyanate compound having an isocyanate structure (Duranate TPA, manufactured by Asahi Kasei Chemicals Co., Ltd.) using hexamethylene diisocyanate as a raw material, and 55 parts by mass Propylene glycol monomethyl ether acetate, 30 parts by mass of polyethylene glycol monomethyl ether (average molecular weight: 750), and maintained at 70 ° C for 4 hours under a nitrogen atmosphere. Then, the temperature of the reaction liquid was lowered to 50 ° C, and 47 parts by mass of methyl ethyl ketone oxime was added dropwise. The infrared spectrum of the reaction liquid was measured, and it was confirmed that the absorption of the isocyanate group disappeared, and a block polyisocyanate aqueous dispersion (C-1) having a solid content of 75 mass% was obtained.

Example 1

(1) Adjustment of coating liquid

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

Water 40.61% by mass

Isopropyl alcohol 30.00% by mass

Polyester water dispersion (Aw-1) 11.67% by mass

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

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

Particle 1.25 mass%

(Coffrite colloid having an average particle diameter 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

(oxygen system, solid concentration 10% by mass)

(2) Manufacture of polyester film for polarizer protection

PET resin particles having an intrinsic viscosity (solvent: phenol/tetrachloroethane = 60/40) of 0.62 dl/g and substantially no particles, which is a film raw material polymer, under a reduced pressure of 133 Pa, at 135 Dry at °C for 6 hours. Then, it was supplied to an extruder, melt-extruded into a sheet shape at about 280 ° C, and rapidly cooled and adhered to a rotary cooling metal roll having 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 extended in a longitudinal direction by 3.5 times with a roll group having a circumferential speed difference to obtain a uniaxially stretched PET film.

Next, the coating liquid was applied to one surface of the PET film by a roll coating method, and then dried at 80 ° C for 15 seconds. Further, the amount of coating after drying (after biaxial stretching) was adjusted to 0.12 g/m ² . Subsequently, the film was stretched 4.0 times in the width direction at 150 ° C by a tenter, and heated at 230 ° C for 0.5 second in a state where the length in the width direction of the film was fixed, and then carried out at 230 ° C for 10 seconds in a width direction of 3%. The film was subjected to a relaxation treatment to obtain a polarizer-protected polyester film having a thickness of 38 μm. The evaluation results are shown in Table 3.

Example 2

A polarizer was prepared in the same manner as in Example 1 except that the aqueous polyester dispersion was changed to an aqueous dispersion (Aw-2) obtained by dispersing a polyester resin having an acid value of 4 KOH mg/g. Protective polyester film.

Example 3

A polarizer was obtained in the same manner as in Example 1 except that the aqueous polyester dispersion was changed to an aqueous dispersion (Aw-3) obtained by dispersing a polyester resin having an acid value of 6 KOH mg/g. Protective polyester film.

Example 4

A polyester film for protecting a polarizer was prepared in the same manner as in Example 1 except that the polyvinyl alcohol aqueous solution was changed to a polyvinyl alcohol aqueous solution (Bw-3) having a saponification value of 79 mol% of polyvinyl alcohol. .

Example 5

A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyvinyl alcohol aqueous solution (Bw-2) having a saponification value of 83 mol% of polyvinyl alcohol was changed.

Example 6

In the same manner as in Example 1, except that the mass ratio of the polyester resin (A)/polyvinyl alcohol resin (B) was changed to 60/40, the following coating agent was used to obtain a polarizer protection. Polyester film.

Water 37.28% by mass

Isopropyl alcohol 30.00% by mass

Polyester water dispersion (Aw-1) 10.00% by mass

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

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

Particle 1.25 mass%

(Coffrite colloid having an average particle diameter 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

(oxygen system, solid concentration 10% by mass)

Example 7

In the same manner as in Example 1, except that the mass ratio of the polyester resin (A)/polyvinyl alcohol resin (B) was changed to 80/20, the following coating agent was used to obtain a polarizer protection. Polyester film.

Water 43.95% by mass

Isopropyl alcohol 30.00% by mass

Polyester water dispersion (Aw-1) 13.33% by mass

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

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

Particle 1.25 mass%

(Coffrite colloid having an average particle diameter 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

(oxygen system, solid concentration 10% by mass)

Example 8

In the same manner as in Example 1, except that the mass ratio of the polyester resin (A)/polyvinyl alcohol resin (B) was changed to 50/50, the following coating agent was used to obtain a polarizer protection. Polyester film.

Water 33.95 mass%

Isopropyl alcohol 30.00% by mass

Polyester water dispersion (Aw-1) 8.33% by mass

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

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

Particle 1.25 mass%

(Coffrite colloid having an average particle diameter 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

(oxygen system, solid concentration 10% by mass)

Example 9

A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the composition of the coating liquid was changed as described below.

Water 40.87 mass%

Isopropyl alcohol 30.00% by mass

Polyester water dispersion (Aw-1) 11.67% by mass

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

Melamine crosslinker (C-2) 0.71% by mass

(Nikalac MX-042, solid concentration of 70% from Sanhe Chemical)

Particle 1.25 mass%

(Coffrite colloid having an average particle diameter of 100 nm, solid content concentration of 40% by mass)

Surfactant 0.5% by mass

(oxygen system, solid concentration 10% by mass)

Example 10

A polarizer was obtained in the same manner as in Example 1 except that the aqueous solution of polyvinyl alcohol was changed to an aqueous solution (Bw-5) obtained by dissolving polyvinyl alcohol having a saponification value of 70 mol% of polyvinyl alcohol. Protective polyester film.

Example 11

A polarizer was obtained in the same manner as in Example 1 except that the aqueous solution of polyvinyl alcohol was changed to an aqueous solution (Bw-6) obtained by dissolving polyvinyl alcohol having a saponification value of 67 mol% of polyvinyl alcohol. Protective polyester film.

Example 12

A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the composition of the coating liquid was changed as described below.

Water 40.33% by mass

Isopropyl alcohol 30.00% by mass

Polyester water dispersion (Aw-1) 11.67% by mass

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

Oxazoline crosslinking agent (C-3) 1.25 mass%

(Epocros WS-500, Japan Catalyst, solid content concentration 40% by mass)

Particle 1.25 mass%

(Coffrite colloid having an average particle diameter of 100 nm, solid content concentration of 40% by mass)

Surfactant 0.5% by mass

(oxygen system, solid concentration 10% by mass)

Example 13

In the same manner as in Example 1, except that the aqueous polyester dispersion was changed to an aqueous dispersion (Aw-5) obtained by dispersing a polyester resin having an acid value of 10 KOH mg/g, polarized light was obtained in the same manner as in Example 1. A polyester film for sub-protection.

Comparative example 1

In the same manner as in Example 1, except that the mass ratio of the polyester resin (A)/polyvinyl alcohol resin (B) was changed to 100/0, the following coating agent was used to obtain a photoprotector. Polyester film.

Water 50.62% by mass

Isopropyl alcohol 30.00% by mass

Polyester water dispersion (Aw-1) 16.66% by mass

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

Particle 1.25 mass%

(Coffrite colloid having an average particle diameter 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

(oxygen system, solid concentration 10% by mass)

Comparative example 2

In the same manner as in Example 1, except that the mass ratio of the polyester resin (A)/polyvinyl alcohol resin (B) was changed to 0/100, the following coating agent was used to obtain a polarizer protection. Polyester film.

Water 17.28% by mass

Isopropyl alcohol 30.00% by mass

Polyvinyl alcohol aqueous solution (Bw-4) 50.00% by mass

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

Particle 1.25 mass%

(Coffrite colloid having an average particle diameter 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

(oxygen system, solid concentration 10% by mass)

Comparative example 3

In the same manner as in Example 1, except that the aqueous polyester dispersion was changed to an aqueous dispersion (Aw-3) obtained by dispersing a polyester resin having an acid value of 25 KOH mg/g, polarizer protection was obtained in the same manner as in Example 1. Use a polyester film.

Comparative example 4

A polyester 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 a polyvinyl alcohol aqueous solution (Bw-1) obtained by dissolving a saponification value of 88 mol%. .

Comparative Example 5

A polarizer was obtained in the same manner as in Example 1 except that the aqueous solution of polyvinyl alcohol was changed to an aqueous solution (Bw-7) obtained by dissolving polyvinyl alcohol having a saponification value of 40 mol% of polyvinyl alcohol. Protective polyester film.

Comparative Example 6

A polyester film for protecting a polarizer was prepared in the same manner as in Example 1 except that the following coating agent was mixed.

Water 41.58 mass%

Isopropyl alcohol 30.00% by mass

Polyester water dispersion (Aw-1) 11.67% by mass

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

Particle 1.25 mass%

(Coffrite colloid having an average particle diameter of 100 nm, solid content concentration of 40% by mass)

Surfactant 0.5% by mass

(oxygen system, solid concentration 10% by mass)

Reference example 1

A TAC film (manufactured by Fujifilm Co., Ltd., thickness: 80 μm, saponified) was used as a film for polarizer protection, and the results of the above adhesion test were as follows.

[Industrial Applicability]

The easy-adhesive polyester film for polarizer protection of the present invention has high adhesion to a polarizer and a water-based adhesive. Therefore, it can be suitably used as a polarizer protection member.

Claims (5)

An easy-adhesive polyester film for protecting a photo-photon having an easy-adhesive layer on at least one side thereof; the easy-adhesion layer containing a polyester resin (A), a polyvinyl alcohol-based resin (B), and a crosslinking agent ( C); the polyester resin (A) has an acid value of 20 KOH mg/g or less; and the polyvinyl alcohol-based resin (B) has a saponification value of 60 to 85 mol%. The easy-bonding polyester film for polarizing photoprotection according to claim 1, wherein the polyester resin (A) contains 1 to 15 mol% of 5-sulfonic acid isophthalic acid in the dicarboxylic acid component. . The easy-contact polyester film for polarizer protection according to claim 1 or 2, wherein the crosslinking agent (C) is an isocyanate compound or a melamine compound. The easy-contact polyester film for polarizer protection according to the first or second aspect of the invention, wherein the polyester resin (A), the polyvinyl alcohol resin (B), and the crosslinking agent (C) The mass ratio satisfies the following formula: 0.8 ≦ (A) / (B) ≦ 5 0.2 ≦ ((A) + (B)) / (C) ≦ 50. A polarizing plate having a polarizer protective film on both sides of a polarizer; and a polarizer protective film on at least one side thereof is an easy-conjunction polycondenser for polarizer protection according to any one of claims 1 to 4. Ester film.