JP2014034124A - Polarizer protective polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizer protective polyester film excellent in adhesiveness to a polarizer and a functional layer such as a hard coat layer.SOLUTION: The polarizer protective polyester film includes an easily adhesive layer P1 on one surface of a polyester film and an easily adhesive layer P2 on the other surface. The easily adhesive layer P1 comprises a polyester resin (A), a polyvinyl alcohol resin (B) and a crosslinking agent (C), wherein the polyester resin (A) has an acid value of 20 KOH mg/g or less and the polyvinyl alcohol resin (B) has a saponification degree of 60 to 85 mol%. The easily adhesive layer P2 comprises, as main components, a urethane resin (D) having an aliphatic polycarbonate polyol as a constituent component, and a crosslinking agent (E).

Description

  The present invention relates to a polyester film for protecting a polarizer used for protecting a polarizer. In detail, it is related with the polyester film for polarizer protection excellent in adhesiveness with a polarizer.

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

However, triacetyl cellulose is not sufficiently durable, and when a polarizing plate using a triacetyl cellulose film as a polarizer protective film is used at high temperature or high humidity, the performance of the polarizing plate such as the degree of polarization and hue deteriorates. There is a case. In recent years, there has been a demand for thinning the polarizing plate in order to cope with the thinning of the display. However, from the viewpoint of maintaining moisture barrier properties, there has been a limit to thinning the triacetyl cellulose film. Therefore, it has been proposed to use a polyester film as a polarizer protective film having durability and moisture barrier properties (see Patent Documents 1 to 5).
The triacetyl cellulose film used as a polarizer protective film is subjected to alkali treatment or the like on its surface, and has an extremely high affinity with a hydrophilic adhesive. Therefore, the protective film made of a triacetyl cellulose film has extremely high adhesiveness with a polarizer coated with a hydrophilic adhesive. However, the polyester film has insufficient adhesion to the hydrophilic adhesive, and this tendency becomes more prominent particularly in the case of a polyester film having orientation by a stretching treatment. Therefore, Patent Documents 1 to 3 and 5 propose providing a polyester film with an easy-adhesion layer in order to improve the adhesion to the polarizer or the hydrophilic adhesive applied to the polarizer.

JP-A-8-271733 JP-A-8-271734 JP 2009-157361 A JP 2010-277028 A JP 2011-8170 A

A polyester film has a low affinity for water, and this tendency is particularly remarkable in a polyester film having an aromatic dicarboxylic acid as a dicarboxylic acid component. Moreover, the polyester film which has crystal orientation by extending | stretching has a low affinity with water further. On the other hand, the polarizer and the adhesive applied on the polarizer are mainly composed of a polyvinyl alcohol-based resin and have high hydrophilicity. Due to the difference in properties, the polyester film, the polarizer, and the adhesive have low affinity, and it has been difficult to firmly bond the two. Therefore, even if it is a polyester film which has an easily bonding layer disclosed by patent documents 1-3 and 5, compared with a triacetyl cellulose film, sufficient adhesiveness is not yet acquired. Therefore, when a polarizing plate using a conventional polyester film as a protective film is used as a display member for a long time, floating or peeling occurs between the protective film and the polarizer, and the polarization characteristics deteriorate due to a change in the amount of moisture in the polarizer. Visibility such as white spots may deteriorate.
Under such circumstances, the object of the present invention is to provide a polarizer protective film comprising means for firmly bonding a polyester film and a polyvinyl alcohol resin layer such as an adhesive applied on the polarizer or the polarizer, and An object is to provide a polarizing plate and a liquid crystal display device using them. The present invention also has a polarizer protective film and a polarizing plate having the above-mentioned properties and excellent adhesion to a functional layer such as a hard coat layer (particularly, adhesion under high temperature and high humidity conditions), and these. It is a further object to provide a liquid crystal display device.

The inventors of the present invention have made extensive studies and examinations to solve the above problems, and have a polyester resin having a high affinity with a polyester film and a polyvinyl alcohol resin having a high affinity with a polyvinyl alcohol resin layer and a crosslinking agent. It came to the idea of providing the layer to contain between a polyester film and a polyvinyl alcohol-type resin layer. However, the present inventors have found that the function of closely adhering the polyester film and the polyvinyl alcohol-based resin layer due to each component cannot be sufficiently exhibited by simply combining these components. Therefore, as a result of repeated researches day and night, the present inventors adopted a polyester resin having a certain acid value as the polyester resin in the above concept, and further, polyvinyl alcohol having a certain degree of saponification as the polyvinyl alcohol resin. It has been found that by using a system resin, it is possible to effectively exert the adhesive action of each component with a resin layer having high affinity.
As a result of further research based on the above findings, the present inventors have adopted a cross-linking agent having high reactivity with a hydroxyl group, so that a polyester film and a polyvinyl alcohol resin layer such as a polarizer and an adhesive are used. It has been found that it is possible to adhere to each other more firmly.
As a result of further intensive studies, the present inventors have found that a coating layer mainly composed of a urethane resin comprising a aliphatic polycarbonate polyol and a crosslinking agent as a main component on the surface opposite to the above-described layer of the polyester film. It was found that the adhesiveness with a functional layer such as a hard coat layer (particularly, adhesion under high temperature and high humidity conditions) is excellent.
Based on these findings, the present inventors have made further studies and considerations, and have invented the present invention.

Below, the typical example of this invention is shown.
Item 1.
A polyester film for protecting a polarizer having an easy adhesion layer P1 on one side of the polyester film and an easy adhesion layer P2 on the other side, wherein the easy adhesion layer P1 comprises a polyester resin (A) and a polyvinyl alcohol resin. (B) and a crosslinking agent (C) are included, the acid value of the polyester resin (A) is 20 KOH mg / g or less, and the saponification degree of the polyvinyl alcohol resin (B) is 60 to 85 mol%. The polyester film for protecting a polarizer, wherein the easy-adhesion layer P2 contains a urethane resin (D) and a crosslinking agent (E) containing aliphatic polycarbonate polyol as constituent components.
Item 2.
Item 2. The polyester film for protecting a polarizer according to Item 1, wherein the polyester resin (A) contains 1 to 15 mol% of a 5-sulfoisophthalic acid component in the dicarboxylic acid component.
Item 3.
Item 3. The polyester film for protecting a polarizer according to Item 1 or 2, wherein the crosslinking agent (C) is an isocyanate compound or a melamine compound.
Item 4.
Item 4. The polarized light according to any one of Items 1 to 3, wherein a mass ratio of the polyester resin (A), the polyvinyl alcohol resin (B), and the crosslinking agent (C) in the easy adhesion layer P1 satisfies the following formula. Child protective polyester film.
0.8 ≦ (A) / (B) ≦ 5
2 ≦ ((A) + (B)) / (C) ≦ 50
Item 5.
The ratio (A ₁₄₆₀ / A ₁₅₃₀ ) of the absorbance (A ₁₄₆₀ ) near 1460 cm ⁻¹ derived from the aliphatic polycarbonate component of the polyurethane resin (D) and the absorbance (A ₁₅₃₀ ) near 1530 cm ⁻¹ derived from the urethane component is Item 5. The polyester film for protecting a polarizer according to any one of Items 1 to 4, which is 0.40 to 1.55.
Item 6.
The said crosslinking agent (E) is at least 1 sort (s) selected from the group which consists of a melamine type crosslinking agent, an isocyanate type crosslinking agent, a carbodiimide type crosslinking agent, and an oxazoline type crosslinking agent in any one of claim | item 1 -5. Polyester film for protecting polarizers.
Item 7.
The polyester film for polarizer protection in any one of claim | item 1 -6 whose mass ratio (D / E) of a urethane resin (D) and a crosslinking agent (E) is 1 / 9-9 / 1.
Item 8.
Having at least one functional layer selected from the group consisting of a hard coat layer, an antiglare layer, an antiglare antireflection layer, an antireflection layer and a low reflection layer on the easily adhesive layer P2 of the polyester film for protecting the polarizer. Item 8. A polyester film for protecting a polarizer according to any one of Items 1 to 7.
Item 9.
The polarizing plate which has a polarizer protective film on both surfaces of a polarizer, Comprising: The polarizing plate whose polarizer protective film of an at least one surface is a polyester film for polarizer protection in any one of claim | item 1 -8. .
Item 10.
Item 10. A liquid crystal display device comprising at least one polarizing plate according to item 9.

  The polyester film for protecting a polarizer of the present invention is excellent in adhesion to a polarizer or a polyvinyl alcohol-based resin layer represented by an adhesive applied thereon. Furthermore, it is excellent in adhesion (humidity heat resistance) with various functional layers under high temperature and high humidity. Therefore, the film for protecting a polarizer of the present invention is less likely to cause a decrease in adhesiveness with a functional layer over time even under high temperature and high humidity conditions, and thus the initial adhesiveness can be maintained for a long time. . 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, it is possible to produce a polarizing plate having superior durability and water barrier properties at a lower cost than before. Moreover, since the polarizing plate of the present invention is excellent in durability, it can be made thinner than before. Therefore, it is possible to further reduce the thickness of the liquid crystal display by using the polarizing plate of the present invention.

1. Polyester film The polyester film used as a substrate in the present invention is a film mainly composed of a polyester resin. Here, “a film mainly composed of a polyester resin” is a film formed from a resin composition containing 50% by mass or more of a polyester resin. When blended with another polymer, the polyester resin is 50% by mass. % When it is copolymerized with other monomers, it means that 50 mol% or more of the polyester structural unit is contained. Preferably, the polyester film contains a polyester resin in an amount of 90% by mass or more, more preferably 95% by mass or more, and still more preferably 100% by mass.

The material of the polyester resin is not particularly limited, but a copolymer formed by polycondensation of a dicarboxylic acid component and a diol component or a blend resin thereof can be used. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and diphenyl. Carboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracene dicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydro Isophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid The die Over acid, sebacic acid, suberic acid, dodecamethylene dicarboxylic 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, decamethylene glycol, 1,3- Examples include propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, and bis (4-hydroxyphenyl) sulfone.
Each of the dicarboxylic acid component and the diol component constituting the polyester resin may be used alone or in combination of two or more. Further, other acid components such as trimellitic acid and other hydroxyl components such as trimethylolpropane may be appropriately added.

  Specific examples of the polyester resin include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Among these, polyethylene terephthalate is preferable from the balance of physical properties and cost. Moreover, in order to control optical characteristics, such as polarization, it is also a preferable aspect that other copolymer components or other polymers are included. Preferred copolymer components from the viewpoint of controlling the optical properties of the polyester film include diethylene glycol and copolymer components having norbornene in the side chain.

  Since the polyester film of the present invention is used as a protective film for a polarizer, it preferably has high transparency. The transparency of the polyester film for protecting a polarizer of the present invention is preferably such that the total light transmittance is 85% or more, more preferably 87% or more, still more preferably 88% or more, and even more preferably 89% or more. 90% or more is particularly preferable. The haze is preferably 3% or less, more preferably 2.5% or less, further preferably 2% or less, and particularly preferably 1.5% or less. 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 rollability of the polyester film, inert particles may be included in the film. However, in order to maintain high transparency, the inert particles in the film may be included. The content is preferably as low as possible. Therefore, a multilayer structure in which particles are included only in the surface layer of the film, or particles are substantially not included in the film, and particles are included only in the easy-adhesion layer laminated on at least one side of the polyester film. It is preferable.

  “Substantially no particles” means, for example, in the case of inorganic particles, when the element derived from the particles is quantitatively analyzed by fluorescent X-ray analysis, 50 ppm or less, preferably 10 ppm or less, most preferably detected The content is below the limit. This means that even if particles are not actively added to the base film, contaminants derived from foreign substances and raw material resin or dirt adhering to the line or equipment in the film manufacturing process will be peeled off and mixed into the film. It is because there is a case to do.

  In addition, when the base film has a multi-layer structure, the two-layer / three-layer structure that does not substantially contain inert particles in the inner layer and contains inert particles only in the outermost layer achieves both transparency and workability. It is possible and preferable.

  In the present invention, the thickness of the film is not particularly limited, but when the thickness of the polarizing plate is reduced in order to make the display thinner, 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 the protective film, the thickness of the film is preferably 10 μm or more, more preferably 12 μm or more, and further preferably 20 μm or more.

  The polyester film used as the substrate may be a single layer or a laminate of two or more layers. Moreover, as long as it exists in the range with the effect of this invention, various additives can be contained in a film as needed. Examples of the additive include an antioxidant, a light resistance agent, an antigelling agent, an organic wetting agent, an antistatic agent, an ultraviolet absorber, and a surfactant. 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 the polarizer, it is also a preferred embodiment to add an ultraviolet absorber or the like to the inner layer.

  The polyester film is obtained by, for example, a method of forming the film by melt-extruding the above-described polyester resin into a film and cooling and solidifying with a casting drum. As the polyester film, either an unstretched film or a stretched film can be used, but a stretched film is preferable from the viewpoint of durability such as 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 longitudinal and transverse sequential biaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, and the like can be employed.

2. Easy adhesion layer P1
The polyester film for protecting a polarizer of the present invention has an acid value on one side of the polyester film in order to improve the adhesion between the polarizer and a polyvinyl alcohol-based resin layer such as an aqueous adhesive provided on one or both sides thereof. Easy adhesion molded from a resin composition containing a polyester resin (A) of 20 KOHmg / g or less, a polyvinyl alcohol resin (B) having a saponification degree of 60 to 85 mol%, and a crosslinking agent (C). The layer P1 is laminated.

Although not limited by theory, it is crosslinked with a specific polyester resin (A) having an acid value of 20 KOHmg / g or less and a specific polyvinyl alcohol resin (B) having a saponification degree of 60 to 85 mol%. By combining the agent (C), it is considered that the polyester-based resin and the polyvinyl alcohol-based resin form separate domain units in the easy-adhesion layer, and form a phase separation structure generally called a sea-island structure. By adopting such a domain unit separation structure, the adhesiveness to the polyester film by the domain constituted by the polyester resin and the adhesiveness to the polyvinyl alcohol resin layer by the domain constituted by the polyvinyl alcohol resin are two. It is considered that the two functions are preferably compatible with each other without being impaired. The crosslinking agent (C) is considered to promote and maintain the formation of the domain structure by crosslinking and aggregating the polyvinyl alcohol resin (B).
Hereinafter, each composition of the easily bonding layer P1 is explained in full detail.

(Polyester resin (A))
The polyester resin (A) used for the easy-adhesion layer is a copolymer obtained by polycondensation of a dicarboxylic acid component and a diol component, and the aforementioned materials can be used as the dicarboxylic acid component and the diol component. From the viewpoint of improving the adhesion to the polyester film substrate, it is preferable to use a dicarboxylic acid component having the same or similar structure and properties as the dicarboxylic acid component in the polyester film as the dicarboxylic acid component of the polyester resin (A). . Therefore, for example, when an aromatic dicarboxylic acid is employed as the dicarboxylic acid component of the polyester film, it is preferable to use the aromatic dicarboxylic acid as the dicarboxylic acid component of the polyester resin (A). As such an aromatic dicarboxylic acid component, terephthalic acid and isophthalic acid are most preferred. Other aromatic dicarboxylic acids may be added and copolymerized within a range of 10 mol% or less with respect to the total dicarboxylic acid component.
Moreover, as a glycol component of a polyester-type resin (A), it is preferable to make ethylene glycol and the branched glycol into a structural component. By having a branched structure, it is considered that it contributes to stress relaxation in the easy-adhesion layer, and it is possible to suitably exhibit adhesion. Examples of the branched glycol component include 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, and 2-methyl-2-butyl-1,3. -Propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-methyl-2-n-hexyl-1,3-propanediol 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl-2-n-hexyl-1,3-propanediol, 2, Such as 2-di-n-butyl-1,3-propanediol, 2-n-butyl-2-propyl-1,3-propanediol, and 2,2-di-n-hexyl-1,3-propanediol. And the like.

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

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

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

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

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

  40 mass% or more and 90 mass% or less are preferable, as for content of the polyester-type resin (A) in the easily bonding layer P1, 45 mass% or more and 85% mass% or less are more preferable, and 50 mass% or more and 80 mass% or less are further. preferable. When the content of the polyester resin (A) is at least the above lower limit, it is suitable for adhesion to the polyester film substrate, and when it is at most the above upper limit, it is suitable for adhesion to the polarizer / aqueous resin.

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

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

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

  The content of the polyvinyl alcohol resin (B) is preferably 10% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 55% by mass or less, and more preferably 20% by mass or more and 50% by mass or less in the easy-adhesion layer P1. Is more preferable. When the content of the polyvinyl alcohol resin (B) is not less than the above lower limit, it is suitable for adhesion to a polarizer / water-based resin, and when it is not more than the above upper limit, it is suitable for adhesion to a polyester film substrate.

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

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

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

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

  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 further preferably 8% by mass or more and 30% by mass or less in the easy-adhesion layer P1. preferable. When the content of the crosslinking agent (C) is not less than the above lower limit, it is suitable for forming a crosslinked polyvinyl alcohol resin, and when it is not more than the above upper limit, it is suitable for expression of an adhesive effect by the binder resin.

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

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

  By adopting the above composition, the easy-adhesion layer P1 of the present invention exhibits high adhesiveness equivalent to that of triacetyl cellulose to polarizers and aqueous adhesives, particularly polyvinyl alcohol-based polarizers and aqueous adhesives. Specifically, the remaining area after peeling once is preferably 90% or more, more preferably 95% or more, and further preferably 100% with respect to the water-based adhesive according to the adhesive test described later. The remaining area after is preferably 75% or more, more preferably 85% or more, further preferably 95% or more, and the remaining area after 10 continuous peelings is preferably 50% or more, more preferably 80% or more, Preferably it is 90% or more, More preferably, it is 93% or more, Most preferably, it is 95% or more.

3. Easy adhesion layer P2
The polyester film for protecting a polarizer of the present invention contains, as main components, a urethane resin (D) and a cross-linking agent (E) containing aliphatic polycarbonate polyol as constituent components in order to improve adhesion to various functional layers. Easy adhesion layer P2 is laminated. Here, the “main component” means that it is contained in an amount of 50% by mass or more, more preferably 70% by mass or more as a total solid component contained in the easy-adhesion layer.

  When functional layers such as a hard coat layer, antiglare layer, antiglare antireflection layer, antireflection layer, and low reflection layer are laminated on the base polyester film, shrinkage during curing of the curable resin constituting the functional layer Due to the swelling during the high-temperature and high-humidity treatment, a strong stress is generated between the functional layer and the easy adhesion layer. When such a laminated film is placed under high temperature and high humidity, the coating layer deteriorates due to dissolution or swelling or hydrolysis by a solvent contained in the curable resin. As a result, it was considered that the above-mentioned stress could not be endured, the functional layer was peeled off, and the adhesion was lowered. Therefore, in order to maintain a high degree of adhesion under high temperature and high humidity, the adhesive layer has not only a strong cross-linking property but also a hydrolysis resistance, as well as a flexibility that can withstand the stress. Is considered desirable. However, simply having flexibility is problematic in terms of solvent resistance and strength. Therefore, it is most desirable to make these conflicting characteristics compatible.

In the present invention, an aliphatic polycarbonate component which is an easy-adhesion layer mainly composed of a urethane resin (D) and a crosslinking agent (E) containing aliphatic polycarbonate polyol as components, and is measured by infrared spectroscopy. The ratio (A ₁₄₆₀ / A ₁₅₃₀ ) of the absorbance around 1460 cm ⁻¹ from the origin (A ₁₄₆₀ ) and the absorbance around 1530 cm ⁻¹ from the urethane component (A ₁₅₃₀ ) is preferably 0.40 to 1.55. That is, the above-mentioned characteristics can be achieved by coexisting a predetermined amount of an aliphatic polycarbonate component having hydrolysis resistance and flexibility and a urethane component exhibiting toughness while providing solvent resistance with a crosslinking agent. Plan. As a result, it is possible to relieve stress due to shrinkage during curing of the photocurable resin and swelling during high-temperature and high-humidity treatment, so that it is possible to obtain good adhesion with various curable resins, etc. We believe that even under high-humidity environments, it is possible to prevent deterioration of the easy-adhesion layer such as dissolution, swelling, and hydrolysis due to the solvent and diluent monomer remaining in the easy-adhesion layer

Absorbance (A ₁₄₆₀ ) near 1460 cm ⁻¹ is derived from the bending vibration specific to the CH bond of the methylene group contained in the aliphatic polycarbonate component. Therefore, the magnitude of absorbance (A ₁₄₆₀ ) near 1460 cm ⁻¹ depends on the amount of the aliphatic polycarbonate polyol component constituting the urethane resin present in the easy-adhesion layer. On the other hand, the absorbance (A ₁₅₃₀ ) in the vicinity of 1530 cm ⁻¹ is derived from the bending vibration specific to the N—H bond contained in the urethane component. Therefore, the magnitude of absorbance (A ₁₅₃₀ ) near 1530 cm ⁻¹ depends on the amount of urethane components (number of urethane bonds) constituting the urethane resin present in the easy-adhesion layer. Moreover, when using an isocyanate type crosslinking agent as a crosslinking agent, the magnitude | size of the light absorbency ( _A1530 ) vicinity of 1530cm < ^-1 > is the amount of urethane components (the number of urethane bonds) as the sum total of the urethane resin and crosslinking agent amount which exist in an easily bonding layer. ). Therefore, these absorbance ratios (A ₁₄₆₀ / A ₁₅₃₀ ) indicate that both components having different characteristics coexist in a specific ratio. In the present invention, the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) is preferably 0.40 to 1.55, but the lower limit of the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) is more preferably 0.45, Preferably it is 0.50. The upper limit of the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) is more preferably 1.50, still more preferably 1.40, particularly preferably 1.30, and most preferably 1.20. When the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) is less than 0.40, there are too many hard urethane components, and the stress relaxation of the easy-adhesion layer tends to decrease, so the heat and humidity resistance may decrease. On the other hand, when the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) exceeds 1.55, there are too many aliphatic components in the flexible aliphatic polycarbonate, and the solvent resistance of the easy-adhesion layer tends to decrease, so that the moisture resistance Thermal properties may decrease.

(Urethane resin D)
The urethane resin (D) constituting the easy-adhesion layer P2 contains at least a polyol component and a polyisocyanate component as constituent components, and further contains a chain extender as necessary. The urethane resin (D) of the present invention is a polymer compound obtained by copolymerizing these constituent components mainly by urethane bonds. In this invention, it has an aliphatic polycarbonate polyol as a structural component of a urethane resin (D), It is characterized by the above-mentioned. Moisture heat resistance can be improved by including the urethane resin (D) containing aliphatic polycarbonate as a constituent component in the easy-adhesion layer P2 of the present invention. In addition, the structural component of these urethane resins (D) can be specified by nuclear magnetic resonance analysis or the like.

  The diol component that is a constituent component of the urethane resin (D) needs to contain an aliphatic polycarbonate polyol having excellent heat resistance and hydrolysis resistance. In view of preventing yellowing, it is preferable to use an aliphatic polycarbonate polyol.

  Examples of the aliphatic polycarbonate polyol include aliphatic polycarbonate diols and aliphatic polycarbonate triols, and aliphatic polycarbonate diols can be preferably used. Examples of the aliphatic polycarbonate diol that is a constituent component of the urethane resin (D) of the present invention include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1 Aliphatic polycarbonate diol obtained by reacting one or more of diols such as 1,4-cyclohexanedimethanol and carbonates such as dimethyl carbonate, diphenyl carbonate, ethylene carbonate, and phosgene. Etc., and the like.

The number average molecular weight of the aliphatic polycarbonate diol is preferably 1500 to 4000, and more preferably 2000 to 3000. When the number average molecular weight of the aliphatic polycarbonate diol is small, the ratio of the aliphatic polycarbonate component constituting the urethane resin is relatively small. Therefore, in order to make the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) within the above range, it is preferable to control the number average molecular weight of the aliphatic polycarbonate diol within the above range. If the number average molecular weight of the aliphatic polycarbonate diol is large, the absorbance (A ₁₄₆₀ ) in the vicinity of 1460 cm ⁻¹ derived from the aliphatic polycarbonate component increases and the aliphatic component increases, so that the solvent resistance decreases. , The adhesion may be reduced. If the number average molecular weight of the aliphatic polycarbonate diol is small, the hard urethane component increases, and the stress due to shrinkage and swelling of the curable resin constituting the functional layer cannot be relaxed, and the adhesion may be lowered.

  Examples of the polyisocyanate that is a component of the urethane resin of the present invention include aromatic aliphatic diisocyanates such as xylylene diisocyanate, isophorone diisocyanate and 4,4-dicyclohexylmethane diisocyanate, and 1,3-bis (isocyanatomethyl) cyclohexane. Such as alicyclic diisocyanates such as hexamethylene diisocyanate and aliphatic diisocyanates such as 2,2,4-trimethylhexamethylene diisocyanate; Isocyanates. When aromatic isocyanate is used, there is a problem of yellowing, which may not be preferable for optical use requiring high transparency. Moreover, since it becomes a hard coating film compared with an aliphatic type | system | group, it becomes impossible to relieve | moderate the stress by shrinkage | contraction and swelling of curable resin etc. which comprise a functional layer, and adhesiveness may fall.

The ratio (A ₁₄₆₀ / A ₁₅₃₀ ) can also be adjusted by a chain extender. The present invention can be used. Chain extenders include glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol and 1,6-hexanediol, polyhydric alcohols such as glycerin, trimethylolpropane, and pentaerythritol, ethylenediamine Diamines such as hexamethylenediamine and piperazine, aminoalcohols such as monoethanolamine and diethanolamine, thiodiglycols such as thiodiethylene glycol, and water. However, when a chain extender having a short main chain is used, the absorbance (A ₁₅₃₀ ) in the vicinity of 1530 cm ⁻¹ derived from the urethane component increases, and the flexibility of the easy-adhesion layer may decrease. Therefore, a chain extender having a long main chain is preferable. Moreover, the point which provides the softness | flexibility of an application layer has preferable the chain extender of the diol and the diamine whose length of carbon number of a main chain is 4-10. From these points, 1,4-butanediol, 1,6-hexanediol, hexamethylenediamine and the like are preferable as the chain extender used in the present invention.

  The easy-adhesion layer P2 is preferably provided by an in-line coating method described later using an aqueous coating solution. Therefore, it is desirable that the urethane resin (D) of the present invention is water-soluble. The “water-soluble” means that it dissolves in water or an aqueous solution containing less than 50% by mass of a water-soluble organic solvent.

  In order to impart water solubility to the urethane resin, a sulfonic acid (salt) group or a carboxylic acid (salt) group can be introduced (copolymerized) into the urethane molecular skeleton. Since the sulfonic acid (salt) group is strongly acidic and it may be difficult to maintain moisture resistance due to its hygroscopic performance, it is preferable to introduce a weakly acidic carboxylic acid (salt) group. Moreover, nonionic groups, such as a polyoxyalkylene group, can also be introduced.

  In order to introduce a carboxylic acid (salt) group into a urethane resin, for example, as a polyol component, a polyol compound having a carboxylic acid group such as dimethylolpropionic acid or dimethylolbutanoic acid is introduced as a copolymer component to form a salt. Neutralize with an agent. Specific examples of the salt forming agent include trialkylamines such as ammonia, trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, tri-n-butylamine, N such as N-methylmorpholine and N-ethylmorpholine. -N-dialkylalkanolamines such as alkylmorpholines, N-dimethylethanolamine, N-diethylethanolamine and the like. These can be used alone or in combination of two or more.

  In order to impart water solubility, when a polyol compound having a carboxylic acid (salt) group is used as a copolymerization component, the composition molar ratio of the polyol compound having a carboxylic acid (salt) group in the urethane resin is the same as that of the urethane resin. When the total polyisocyanate component is 100 mol%, it is preferably 3 to 60 mol%, more preferably 5 to 40 mol%. If the composition molar ratio is less than 3 mol%, water dispersibility may be difficult. Moreover, when the said composition molar ratio exceeds 60 mol%, since water resistance falls, moist heat resistance may fall.

  The glass transition temperature of the urethane resin (D) of the present invention is preferably less than 0 ° C, more preferably less than -5 ° C. When the glass transition temperature is less than 0 ° C., it is easy to achieve suitable flexibility from the viewpoint of stress relaxation of the coating layer.

  The urethane resin (D) is preferably contained in an amount of 10% by mass to 90% by mass with respect to the crosslinking agent (E). In particular, when high adhesion is required, it is more preferably 20% by mass or more and 80% by mass or less. When the content of the urethane resin is large, the adhesiveness under high temperature and high humidity is lowered, and conversely, when the content is small, the initial adhesiveness is lowered.

  In order to improve the solvent resistance of the urethane resin (D), a self-crosslinking group may be introduced into the urethane resin itself in addition to the addition of the crosslinking agent (E). Thereby, the crosslinking degree of resin increases and solvent resistance improves. Although it does not specifically limit as a self-crosslinking group used for this invention, The comparatively stable silanol group can be used suitably also in aqueous | water-based coating liquid.

  A resin other than the urethane resin (D) may be contained in order to improve adhesion. For example, a urethane resin, an acrylic resin, a polyester resin, or the like containing polyether or polyester as a constituent component can be used.

(Crosslinking agent E)
It is preferable to contain a crosslinking agent (E) in the easy-adhesion layer P2. By containing a crosslinking agent (E), it becomes possible to further improve the adhesiveness under high temperature and high humidity. As the crosslinking agent (E), those which react with a carboxylic acid group, a hydroxyl group, an amino group and the like to form an amide bond, a urethane bond, and a urea bond are preferable because they are hardly deteriorated by high-temperature and high-humidity treatment. Conversely, when an ester bond or an ether bond is involved, it may be hydrolyzable, which is not preferable. Examples of the crosslinking agent (E) suitably used in the present invention include melamine-based, isocyanate-based, carbodiimide-based, and oxazoline-based. Among these, an isocyanate type and a carbodiimide type are preferable from the viewpoint of the stability over time of the coating liquid and the effect of improving the adhesion under high temperature and high humidity treatment. Furthermore, it is particularly preferable to use an isocyanate-based crosslinking agent from the viewpoint that the coating layer has appropriate flexibility and suitably imparts the stress relaxation action of the coating layer. Moreover, in order to promote a crosslinking reaction, a catalyst etc. are used suitably as needed.

  As content of a crosslinking agent (E), 10 to 90 mass% is preferable with respect to a urethane resin (D). More preferably, it is 20 mass% or more and 80 mass% or less. When the amount is small, the solvent resistance of the easy-adhesion layer decreases and the adhesion under high temperature and high humidity decreases.When the amount is large, the flexibility of the resin of the easy-adhesion layer decreases and normal temperature, high temperature and humidity Adhesion at the bottom decreases.

  In the present invention, two types of crosslinking agents may be mixed in the easy-adhesion layer P2 in order to improve the coating film strength. Moreover, in order to promote a crosslinking reaction, a catalyst etc. are used suitably as needed.

(Additive)
In the easy-adhesion layers P1 and P2 of the present invention, known additives such as surfactants, antioxidants, catalysts, heat stabilizers, weathering stabilizers, ultraviolet light absorbers, and the like as long as the effects of the present invention are not impaired. Organic lubricants, pigments, dyes, organic or inorganic particles, antistatic agents, nucleating agents, and the like may be added.

  In this invention, in order to improve the blocking resistance of an easily bonding layer, it is also a preferable aspect to add particle | grains to the easily bonding layers P1 and P2. Examples of the particles contained in the easy-adhesion layer in the present invention include titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay and the like, or a mixture thereof. Inorganic particles such as calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, calcium fluoride and other inorganic particles, styrene-based, acrylic-based, melamine-based, benzoguanamine-based, silicone-based Examples include organic polymer particles.

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

  In the present invention, the thickness of the easy-adhesion layers P1 and P2 can be appropriately set in the range of 0.001 to 2.00 μm, but 0.01 to 1.00 μm is required to achieve both workability and adhesiveness. Is more preferably 0.02 to 0.80 μm, still more preferably 0.05 to 0.50 μm. Adhesiveness will become inadequate that the thickness of an easily bonding layer is less than 0.01 micrometer. When the thickness of the easy-adhesion layer exceeds 2.00 μm, blocking may occur.

4). It is also a preferred embodiment to provide a functional layer on the easy-adhesion layer P2 of the polarizer protective polyester film of the present invention. A functional layer is a hard coat layer, an antiglare layer, an antiglare antireflection layer, an antireflection layer, a low reflection layer, an antistatic layer, etc. for the purpose of preventing reflection, glare suppression, rainbow unevenness suppression, scratch suppression, etc. It means a layer having the above functionality. As the functional layer, various types known in the art can be used, and the type is not particularly limited. Hereinafter, each functional layer will be described.

4-1. Hard coat layer As the hard coat layer laminated on the easy-adhesion layer P2 of the polyester film for protecting a polarizer of the present invention, a known hard coat layer can be used, although not particularly limited, drying, heat, chemical reaction, Alternatively, it is possible to use a resin compound that polymerizes and / or reacts by irradiation with any of electron beams, radiation, and ultraviolet rays. Examples of such a curable resin include melamine-based, acrylic-based, silicon-based, and polyvinyl alcohol-based curable resins, but acrylic resins that are cured by electron beams or ultraviolet rays in terms of obtaining high surface hardness or optical design. A curable resin is preferred.
An acrylic resin that is cured by an electron beam or ultraviolet ray has an acrylate-based functional group. For example, a relatively low molecular weight polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, spiro resin Acetal resins, polybutadiene resins, polythiol polyene resins, oligomers or prepolymers of polyfunctional compounds such as polyhydric alcohols (meth) acrylates and prepolymers and reactive diluents such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methyl Monofunctional monomers such as styrene and N-vinylpyrrolidone as well as polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate Contains rate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, etc. Things can be used.

  In the case of an electron beam or ultraviolet curable resin, as a photopolymerization initiator in the above-mentioned resin, acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, tetramethyltyramium monosulfide, thioxanthones, As a photosensitizer, n-butylamine, triethylamine, tri-n-butylphosphine and the like can be mixed and used. It is preferable that the addition amount of a photoinitiator is 0.1-10 mass parts with respect to 100 mass parts of an electron beam or ultraviolet curable resin.

Although it does not specifically limit as a hardening method of the said coating film, It is preferable to carry out by ultraviolet irradiation. When curing by ultraviolet rays, it is preferable to use ultraviolet rays having a wavelength range of 190 to 380 nm. Curing with ultraviolet rays can be performed, for example, with a metal halide lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a black light fluorescent lamp, or the like. Specific examples of the electron beam source include various electron beam accelerators such as a cockcroft-wald type, a bandegraft type, a resonant transformer type, an insulating core transformer type, a linear type, a dynamitron type, and a high frequency type.

  Siloxane-based thermosetting resins are also useful as the resin for the hard coat layer, and can be produced by hydrolyzing and condensing the organosilane compound alone or in combination of two or more under an acid or base catalyst. In particular, in the case of low reflection, it is more preferable to improve the low refractive index and stain resistance by mixing and hydrolyzing and condensing one or more fluorosilane compounds.

The film thickness of the hard coat layer is preferably 0.5 μm to 20 μm, more preferably 1 μm to 20 μm, and even more preferably 1 μm to 15 μm.

4-2. Anti-glare layer As the anti-glare layer to be laminated on the easy-adhesion layer P2 of the polyester film for protecting a polarizer of the present invention, a known one can be used, forming an uneven shape on the polyester film, and scattering external light. Therefore, the visibility is prevented from being deteriorated due to reflection of external light or reflection of an image. As a method for forming unevenness, a method including applying a resin containing particles having a large particle size or cohesiveness to form an uneven shape on the surface, or laminating a film having unevenness on the layer surface to form an uneven shape There are a method of forming an antiglare layer by transferring the above, a method of forming irregularities by nanoimprinting without containing the particles, and one type or a combination of two or more types can be used.

As the resin used for the anti-glare layer, the same electron beam or ultraviolet curable resin as described in the description relating to the hard coat layer can be used. One or two or more of the above-mentioned resins can be mixed and used. Further, in order to adjust physical properties such as plasticity and surface hardness, a resin that is not cured by an electron beam or ultraviolet rays can be mixed. Examples of resins that are not cured by electron beams or ultraviolet rays include polyurethane, cellulose derivatives, polyesters, acrylic resins, polyvinyl butyral, polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, polycarbonate, and polyamide.

Specific examples of the particles used in the antiglare layer include, for example, particles of inorganic compounds such as silica particles, alumina particles, TiO ₂ particles, or polymethyl methacrylate particles, acrylic-styrene copolymer particles, crosslinked acrylic particles, melamine particles. Preferred are resin particles such as crosslinked melamine particles, polycarbonate particles, polyvinyl chloride particles, benzoguanamine particles, crosslinked benzoguanamine particles, polystyrene particles, and crosslinked polystyrene particles. As the shape, spherical particles having a uniform surface protrusion shape are preferably used, but indefinite shapes such as layered inorganic compounds such as talc and bentonite can also be used. Two or more different kinds of particles may be used in combination. Even if there are two or more kinds of material and two or more kinds of particle sizes, there is no limitation.

The particle size of the particles used in the antiglare layer is 0.5 to 10 μm, more preferably 0.5 to 5 μm, further preferably 0.5 to 3 μm, and still more preferably 0.5 to 1.5 μm. The content of the particles is 1 to 50% by weight, more preferably 2 to 30% by weight, based on the resin.

The film thickness of the antiglare layer is preferably 0.5 μm to 20 μm, more preferably 1 μm to 20 μm, and further preferably 1 μm to 10 μm.

The haze of the polyester film for protecting a polarizer on which the antiglare layer of the present invention is laminated is preferably 1 to 50%. It is more preferably 1 to 30%, and further preferably 2 to 30%.

As the antiglare layer used in the present invention, JP-A-6-18706, JP-A-10-20103, JP-A-2009-227735, JP-A-2009-86361, JP-A-2009-80256, JP-A-2011-81217, JP-A-2010. -204479, Unexamined-Japanese-Patent No. 2010-181898, Unexamined-Japanese-Patent No. 2011-1973329, Unexamined-Japanese-Patent No. 2011-197330, Unexamined-Japanese-Patent No. 2011-215393 etc. can also be used conveniently.

4-3. Anti-glare antireflection layer As the anti-glare anti-reflection layer laminated on the easy-adhesion layer P2 of the polyester film for protecting a polarizer of the present invention, a known anti-glare anti-reflection layer can be used. Is provided with an antiglare layer, and a low refractive index layer is further provided thereon. If necessary, a smooth hard coat layer can be provided under the antiglare layer.

The antiglare layer used in the antiglare antireflection layer is a method of applying a resin containing particles having a large particle size or cohesiveness to form an uneven shape on the surface, or a film having unevenness on the layer surface There is a method of forming an antiglare layer by laminating a concavo-convex shape and a method of forming concavo-convex by nanoimprint without containing the particles, and forming concavo-convex by combining one type or two or more types Can do. Of course, the above-described antiglare layer may be used, or a known one may be used.

For the low refractive index layer used for the antiglare antireflection layer, a resin having a refractive index of 1.52 or less can be used. A more preferable refractive index is 1.35 to 1.49, and a more preferable refractive index is 1.38 to 1.46.

Further, the low refractive index layer preferably satisfies the following formula (I): m · λ / 4 × 0.7 <n1 · d1 <m · λ / 4 × 1.3 in order to achieve a low reflectance.

In the formula, m is a positive odd number, n1 is the refractive index of the low refractive index layer, and d1 is the film thickness (nm) of the low refractive index layer. Further, λ is a wavelength, which is a value in the range of 500 to 600 nm. In addition, satisfy | filling said numerical formula (I) means that m (positive odd number, usually 1) which satisfy | fills numerical formula (I) exists in the said wavelength range.

The material for forming the low refractive index layer will be described below. In the low refractive index layer, a resin having the above refractive index range can be used as the low refractive index resin. Examples of the low refractive index resin include fluorine-containing polymers, polymers of fluorine-containing oligomers, low refractive index inorganic particles (magnesium fluoride, calcium fluoride, silica, hollow silica, etc.) and resins, organosilane hydrolysates, A partially condensed cured product (so-called silica sol-gel film) or the like can be used. In particular, a fluorine-containing polymer that is crosslinked by heat or ionizing radiation and an inorganic ultrafine particle filler for improving the film strength are preferably used.

Examples of the crosslinkable fluorine-containing polymer used in the low refractive index layer include a perfluoroalkyl group-containing silane compound (for example, (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane), and other fluorine-containing monomers. And a fluorine-containing polymer having a monomer for providing a crosslinkable group as a structural unit. Specific examples of the fluorine-containing monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc. ), (Meth) acrylic acid partial or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (manufactured by Osaka Organic Chemicals) and M-2020 (manufactured by Daikin)), fully or partially fluorinated vinyl ethers, and the like. As a monomer for imparting a crosslinkable group, in addition to a (meth) acrylate monomer having a crosslinkable functional group in the molecule like glycidyl methacrylate, it has a carboxyl group, a hydroxyl group, an amino group, a sulfonic acid group, etc. ) Acrylate monomers (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, etc.). It is known from JP-A-10-25388 and JP-A-10-147739 that the latter can introduce a crosslinked structure after copolymerization.

Further, not only a polymer having the above-mentioned fluorine-containing monomer as a structural unit but also a copolymer with a monomer not containing a fluorine atom may be used. There are no particular limitations on the monomer units that can be used in combination. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, acrylic acid 2) -Ethylhexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methylstyrene, etc.), vinyl ethers (methyl) Vinyl ether), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate, etc.), acrylamides (N-tertbutylacrylamide, N-cyclohexylacrylamide, etc.), methacrylamides, Krilo nitrile derivatives and the like can be mentioned.

The average particle size of the ultrafine particle filler used for the low refractive index layer is preferably 0.001 to 0.2 μm, and more preferably 0.001 to 0.05 μm. The particle diameter of the filler is preferably as uniform (monodispersed) as possible. The ultrafine filler having a low refractive index is preferably used and may be an organic ultrafine filler or an inorganic ultrafine filler, but an inorganic ultrafine filler is preferred from the viewpoint of improving the film strength. The amount of the ultrafine filler added is preferably 5 to 70% by mass, more preferably 10 to 50% by mass, and particularly preferably 15 to 30% by mass with respect to the total mass of the low refractive index layer.

The inorganic ultrafine particle filler is preferably amorphous. The inorganic ultrafine particle filler is preferably made of a metal oxide, nitride, sulfide or halide, more preferably a metal oxide or metal halide, and a metal oxide or metal fluoride. Most preferred. As metal atoms, Mg, Ca, Ba, Al, Zn, Fe, Cu, Ti, Sn, In, W, Y, Sb, Mn, Ga, V, Nb, Ta, Ag, Si, B, Bi, Mo Ce, Cd, Be, Pb and Ni are preferable, and Mg, Ca, B and Si are more preferable. An inorganic compound containing two kinds of metals may be used. Particularly preferred inorganic compounds include silicon dioxide and magnesium fluoride.

The inorganic ultrafine particle filler is also preferably used after surface treatment. The surface treatment method includes physical surface treatment such as plasma discharge treatment and corona discharge treatment and chemical surface treatment using a coupling agent, but the use of a coupling agent is preferred. As the coupling agent, an organoalkoxy metal compound (eg, titanium coupling agent, silane coupling agent) is preferably used. When the inorganic ultrafine filler is silica, silane coupling treatment is particularly effective. As a surface treatment agent for the inorganic ultrafine particle filler of the low refractive index layer, it may be used for performing a surface treatment in advance before preparing the layer coating solution, or further added as an additive during the preparation of the layer coating solution. It may be included.

The antiglare antireflection layer used in the present invention is the antiglare antireflection layer disclosed in JP2001-281405, JP2004125958, JP42225675, JP2009-47938, JP2009-157234, and the like. It is also preferable to use it.

4-4. Antireflection layer, low reflection layer As the antireflection layer laminated on the easy-adhesion layer P2 of the polyester film for protecting a polarizer of the present invention, a known one can be used. As an example of the configuration of the antireflection layer, a configuration in which a medium refractive index layer, a high refractive index layer, and a low refractive index layer are sequentially laminated on the easy-adhesion layer P2, a high refractive index layer, and a low refractive index layer in order. A multilayer structure such as a laminated structure is exemplified. Further, even with a configuration having only a low refractive index layer, antireflection performance can be obtained (low reflection layer) if a material having a sufficiently low refractive index is used. Of course, those using other known structures can be used as the antireflection layer.
(Low refractive index layer)
The low refractive index layer is configured by combining a curable resin, low refractive index particles, and the like. For example, it is formed by curing a coating liquid in which hollow silica fine particles are mixed with a curable resin. The refractive index of the low refractive index layer is 1.20 to 1.55, preferably 1.25 to 1.45. When the refractive index of the low refractive index layer is less than 1.20, since the content of the curable resin is small, it is difficult for the low refractive index layer to have sufficient coating strength. On the other hand, when the refractive index exceeds 1.55, the low refractive index layer cannot exhibit sufficient antireflection performance.

  Next, the curable resin which is a component for forming the low refractive index layer is a simple substance or a mixture of fluorine-containing organic compounds. Further, as the curable resin, an organic compound containing no fluorine (hereinafter abbreviated as non-fluorine organic compound) or a mixture or a polymer can be used.

  Examples of the fluorine-containing organic compound include 1- (meth) acryloyloxy-1-perfluoroalkylmethane, 1- (meth) acryloyloxy-2-perfluoroalkylethane, 1,10-bisacryloyloxy-1,1,10, 10-tetrahydroperfluorodecane, 1,10-bisbisacryloyloxy-2,9-dihydroxy-4,4,5,5,6,6,7,7-octafluorodecane, 1,9-bisbisacryloyloxy -2,10-dihydroxy-4,4,5,5,6,6,7,7-octafluorodecane, 2,9-bisbisacryloyloxy-1,10-dihydroxy-4,4,5,5 6,6,7,7-octafluorodecane, 1,2-di (meth) acryloyloxy-3-perfluoroalkylbutane, 2-hydro Cis-1H, 1H, 2H, 3H, 3H-perfluoroalkyl-2 ′, 2′-bis {(meth) acryloyloxymethyl} propionate, α, ω-di (meth) acryloyloxymethylperfluoroalkane, α, β, ψ, ω-tetrakis {(meth) acryloyloxy} -αH, αH, βH, γH, γH, χH, χH, ψH, ωH, ωH-perfluoroalkane and the like are preferable.

  As the non-fluorine organic compound, for example, monofunctional (meth) acrylate [here, (meth) acrylate means a general term including both acrylate and methacrylate. ], Starting materials such as polyfunctional (meth) acrylates and reactive silicon compounds such as tetraethoxysilane. Among these, from the viewpoint of achieving both productivity and hardness, a composition containing an ultraviolet curable organic compound, particularly an ultraviolet curable polyfunctional acrylate, as a main component is preferable. The composition containing such an ultraviolet curable polyfunctional acrylate is not particularly limited. For example, a mixture of two or more known ultraviolet curable polyfunctional acrylates, which is commercially available as an ultraviolet curable hard coat material. And the like. The ultraviolet curable polyfunctional acrylate is not particularly limited. For example, dipentaerythritol hexaacrylate, tetramethylolmethane tetraacrylate, tetramethylolmethane triacrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, 1, Acrylic derivatives of polyfunctional alcohols such as 6-bis (3-acryloyloxy-2-hydroxypropyloxy) hexane, polyethylene glycol diacrylate and polyurethane acrylate are preferred.

As fine particles constituting the low refractive index layer, conventionally known organic or inorganic fine particles can be used. Examples thereof include silicon oxide fine particles and organic resin fine particles. It is also preferable to use hollow silica fine particles. The hollow silica fine particles are fine particles in which silica (silicon dioxide, SiO ₂ ) is formed in a substantially spherical shape and has a hollow portion in the outer shell. The average particle diameter of the hollow silica fine particles is preferably 10 to 100 nm, more preferably 20 to 60 nm. When the average particle diameter of the hollow silica fine particles is smaller than 10 nm, it is not preferable because the production of the hollow silica fine particles becomes difficult. On the other hand, when the average particle size is larger than 100 nm, the light scattering in the low refractive index layer increases, the reflection increases in the thin film, and the antireflection function decreases.

  As the hollow silica fine particles, commercially available particles dispersed in an organic solvent can be used as they are, or various commercially available silica powders can be dispersed in an organic solvent. The hollow silica fine particles can also be synthesized by a method for producing hollow spherical silica-based fine particles having a cavity inside the outer shell, as disclosed in, for example, JP-A-2006-21938.

(High refractive index layer, medium refractive index layer)
The high refractive index layer and the middle refractive index layer are configured by combining inorganic materials, organic materials, and the like. The refractive index of the high refractive index layer is higher than that of the low refractive index layer, preferably 1.60 or more, and preferably 1.60 to 1.90. If it is less than 1.60, sufficient antireflection effect cannot be obtained, and it becomes difficult to form a resin layer exceeding 1.90 by wet coating. The refractive index of the middle refractive index layer is lower than that of the high refractive index layer, higher than that of the low refractive index layer, and is preferably in the range of 1.50 to 1.65.

The material which comprises a high refractive index layer and a medium refractive index layer is not specifically limited, An inorganic material and an organic material can be used. The high refractive index layer and the medium refractive index layer are formed by chemical vapor deposition (CVD) or physical vapor deposition (PVD), particularly by vacuum vapor deposition or sputtering, which is a kind of physical vapor deposition, to form a transparent thin film of inorganic oxide. Although it can be used, an all wet coating method is preferred.

  In the case of forming by wet coating, the high refractive index layer is composed of inorganic fine particles containing at least one metal oxide selected from Ti, Zr, In, Zn, Sn, Al and Sb. A curable resin having a polymerizable group (which can also be used in the hard coat layer of the present invention), a coating composition containing a solvent and a polymerization initiator is applied, and after drying the solvent, heating, ionizing radiation It is preferably formed by curing by irradiation or a combination of both means. In the case of using a curable resin or an initiator, a high refractive index layer can be formed by curing the curable resin by a polymerization reaction by heat and / or ionizing radiation after coating. The middle refractive index layer can be formed using the same material, etc., except that the refractive index is different from that of the high refractive index layer.

(Inorganic fine particles)
As the inorganic fine particles, metal (eg, Ti, Zr, In, Zn, Sn, Sb, Al) oxides are preferred, and zirconium oxide fine particles are most preferred from the viewpoint of refractive index. However, from the viewpoint of conductivity, it is preferable to use inorganic fine particles whose main component is an oxide of at least one kind of metal of Sb, In, and Sn. The refractive index can be adjusted to a predetermined refractive index by changing the amount of the inorganic fine particles. The average particle diameter of the inorganic fine particles in the layer is preferably 1 to 120 nm, more preferably 5 to 100 nm, and further preferably 10 to 100 nm when zirconium oxide is used as a main component. Within this range, haze is suppressed, dispersion stability, and adhesion with the upper layer due to moderate irregularities on the surface become favorable, which is preferable.

  The inorganic fine particles mainly composed of zirconium oxide preferably have a refractive index of 1.90 to 2.80, more preferably 2.10 to 2.80, and 2.20 to 2.80. Most preferred. The addition amount of the inorganic fine particles varies depending on each layer, and the high refractive index layer is 40 to 90% by mass, preferably 50 to 85% by mass, and 60 to 80% by mass with respect to the solid content of the entire high refractive index layer. Further preferred. A medium refractive index layer is 1-60 mass% with respect to solid content of the whole middle refractive index layer, and 3-50 mass% is preferable.

The thickness of the antireflective layer composed of the low refractive index layer and the high refractive index layer varies depending on the structure of the antireflective layer, but is preferably the same thickness as the visible light wavelength or less. For example, when the effect of reducing reflection is shown in visible light, the optical film thickness nH · d of the high refractive index layer is 500 ≦ 4 nH · d (nm) ≦ 750, and the optical film thickness nL · d of the low refractive index layer is: It is designed to satisfy 400 ≦ 4 nL · d (nm) ≦ 650. However, nH and nL are the refractive indexes of the high refractive index layer and the low refractive index layer, respectively, and d is the thickness of the layer.

The polyester film for protecting a polarizer laminated with an antireflection layer preferably has a maximum difference in reflectance amplitude at 500 to 650 nm of 2.0% or less, more preferably 1.0% or less. is there.

Examples of the antireflection layer used in the present invention include JP2003-177209, JP2008-262187, JP2010-170089, JP2004-309711, JP2011-191735, JP2004-322380, and JP2009. -3354, JP 2010-72039 A, and JP 2010-256705 A can also be suitably used.

The functional layer may contain other components in addition to those described above as long as the effects of the invention are not lost. Other components include, but are not limited to, for example, inorganic or organic pigments, polymers, polymerization initiators, polymerization inhibitors, antioxidants, dispersants, surfactants, light stabilizers, leveling agents, An antistatic agent, an ultraviolet absorber, a catalyst, an infrared absorber, a flame retardant, an antifoaming agent, conductive fine particles, a conductive resin, and the like can be added.

The functional layer described above may be provided alone or in combination.

5. Manufacture of Easy-Adhesive Polyester Film for Protecting Polarizer The method for manufacturing a polyester film for protecting a polarizer of the present invention will be described by taking a polyethylene terephthalate (hereinafter abbreviated as PET) film as an example, but is naturally limited to this. It is not a thing.

  After sufficiently drying the PET resin in a vacuum, it is fed to an extruder, and melted PET resin at about 280 ° C. is melt-extruded in a sheet form on a rotating cooling roll from a T-die, cooled and solidified by an electrostatic application method, and unstretched PET Get a sheet. The unstretched PET sheet may have a single layer structure or a multilayer structure by a coextrusion method.

  The obtained unstretched PET sheet is crystallized by 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 longitudinal direction with a roll heated to 80 to 120 ° C. to obtain a uniaxially stretched PET film, and then the end of the film is held with a clip And it guide | induces to the hot air zone heated at 80-180 degreeC, and extends | stretches 2.5 to 5.0 time in the width direction. In the case of uniaxial stretching, the film is stretched 2.5 to 5.0 times in the tenter. After stretching, the film is led to a heat treatment zone at 140 to 240 ° C., and heat treatment is performed for 1 to 60 seconds to complete crystal orientation.

  The easy adhesion layer can be provided after the production of the film or in the production process. In particular, from the viewpoint of productivity, it is preferable to apply the coating liquid to at least one side of the PET film after unstretched or uniaxial stretching to form an easy-adhesion layer.

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

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

6). Manufacture of the polyester film for polarizer protection which laminated | stacked the functional layer Each said functional layer is apply | coated and formed on the easily bonding layer P2 of the polyester film for polarizer protection. The coating solution need not be particularly diluted, but may be diluted with an organic solvent as required for the viscosity, wettability, coating thickness, etc. of the coating solution. The coating layer is applied by applying the coating solution to the above-mentioned film by any known method, drying it as necessary, and then irradiating and heating with an electron beam or ultraviolet rays according to the curing conditions of the coating solution. The functional layer is formed by curing the layer.

7). Polarizing plate The polarizing plate of the present invention is a polarizing plate having a polarizer protective film on both sides of a polarizer, and the polarizer protective film on at least one surface is the polyester film for protecting a polarizer. preferable. The other polarizer protective film may be the polyester film for protecting a polarizer of the present invention, or a film having no birefringence such as a triacetyl cellulose film, an acrylic film, or a norbornene film may be used. preferable.

  Examples of the polarizer include a polyvinyl alcohol film containing a dichroic material such as iodine. The polarizer protective film is bonded to the polarizer directly or via an adhesive layer, but it is preferable to bond the polarizer protective film via an adhesive from the viewpoint of improving adhesiveness. In that case, it is preferable to arrange | position the easily bonding layer P1 of this invention to a polarizer surface or an adhesive bond layer surface. As a preferable polarizer for bonding the polyester film of the present invention, for example, iodine or dichroic material is dyed and adsorbed on a polyvinyl alcohol film, uniaxially stretched in a boric acid aqueous solution, and the stretched state is maintained. The polarizer obtained by performing washing | cleaning and drying is mentioned. The draw ratio of uniaxial stretching is usually about 4 to 8 times. Polyvinyl alcohol is suitable as the polyvinyl alcohol film. “Kuraray Vinylon” [manufactured by Kuraray Co., Ltd.], “Tosero Vinylon” [manufactured by Tosero Co., Ltd.], “Nippon Vinylon” [Nippon Synthetic Chemical Co., Ltd. Commercial products such as “made” can be used. Examples of the dichroic material include iodine, a disazo compound, and a polymethine dye.

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

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

8). Liquid crystal display device As an example, the liquid crystal display device of the present invention includes a liquid crystal cell, a first polarizing plate disposed on the display surface side across the liquid crystal cell, and a second polarized light disposed on the backlight side. A liquid crystal display device having a plate is exemplified. The polarizing plate of the present invention can be used for only one or both of the first polarizing plate and the second polarizing plate.

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

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

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

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

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

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

(6) Total light transmittance of polyester film for protecting polarizer The total light transmittance of the polyester film for protecting a polarizer was measured using a turbidimeter (Nippon Denshoku, NDH2000) in accordance with JIS K7105.

(7) Haze of Polyester Film for Protecting Polarizer The haze of the polarizer protective polyester film was measured using a turbidimeter (Nippon Denshoku, NDH2000) in accordance with JIS K7136.

(8) PVA adhesion On the surface of the easy-adhesion layer P1 of the polyester film for protecting a polarizer, a polyvinyl alcohol aqueous solution (PVA117 manufactured by Kuraray Co., Ltd.) adjusted to a solid content concentration of 5% by mass, the thickness of the polyvinyl alcohol resin layer after drying, It apply | coated with the wire bar so that it might become 2 micrometers, and it dried for 5 minutes at 70 degreeC. As the polyvinyl alcohol aqueous solution, a solution in which a red dye was added so as to facilitate the determination was used. The prepared evaluation target film was attached to a glass plate having a thickness of 5 mm to which a double-sided tape was attached, and the opposite surface of the evaluation target laminated film on which the polyvinyl alcohol resin layer was formed was attached to the double-sided tape. Next, 100 grid-like cuts that penetrated through the polyvinyl alcohol resin layer and reached the base film were made using a cutter guide with a gap interval of 2 mm. Next, an adhesive tape (Cello Tape (registered trademark) CT-24; 24 mm width, manufactured by Nichiban Co., Ltd.) was attached to the grid-shaped cut surface. The air remaining at the interface at the time of pasting was pressed with an eraser to bring it into close contact, and then the work of peeling off the adhesive tape vigorously vertically was performed once, five times and ten times. The number of squares on which the polyvinyl alcohol resin layer was not peeled was counted to determine PVA adhesion. That is, when the PVA layer was not peeled off at all, the PVA adhesion rate was 100, and when all the PVA layer was peeled off, the PVA adhesion rate was 0. In addition, what was partially peeled within one square was also included in the number of peeled.

(9) Absorbance measurement by infrared spectroscopy The easy-adhesion layer P2 was shaved off about the obtained polyester film for polarizer protection, and about 1 mg sample was extract | collected. A pressure was applied to the collected sample to prepare a coating layer sample piece (size: about 50 μm × about 50 μm) molded into a film having a thickness of about 1 μm. Further, a sample piece (blank sample piece) was prepared in the same manner as described above for a PET resin having the same quality as the base film as a blank sample.

  The prepared sample piece was placed on a KBr plate, and an infrared absorption spectrum was measured by a microscopic transmission method under the following conditions. The infrared spectrum of the easy adhesion layer P2 was determined as a difference spectrum between the infrared spectrum obtained from the easy adhesion layer P2 sample piece and the spectrum of the blank sample piece.

Absorbance around 1460 cm ^-1 derived from an aliphatic polycarbonate component _{(A 1460)} is 1460 and the value of the absorption peak height having an absorption maximum in the region of ± 10 cm ^-1, the absorbance in the vicinity of 1530 cm ^-1 derived from urethane component (A ₁₅₃₀ ) is the value of the absorption peak height having an absorption maximum in the region of 1530 ± 10 cm ⁻¹ . The baseline was a line connecting the hems on both sides of each maximum absorption peak. The absorbance ratio was determined from the obtained absorbance by the following formula.
(Absorbance ratio) = A ₁₄₆₀ / A ₁₅₃₀

(Measurement condition)
Apparatus: FT-IR analyzer SPECTRA TECH IRμs / SIRM
Detector: MCT
Resolution: 4cm ^-1
Integration count: 128 times

(10) Adhesive of functional layer 100 masses reaching the base film through the functional layer using a cutter guide with a gap distance of 2 mm in the functional layer of the polyester film for protecting a polarizer having the obtained functional layer. Make eye-shaped cuts. Next, a cellophane adhesive tape (manufactured by Nichiban Co., Ltd., No. 405; 24 mm width) was attached to the cut surface of the grid and rubbed with an eraser for complete adhesion. Then, after performing the work of peeling the cellophane adhesive tape vertically from the functional layer surface of the polarizer protective film five times, the number of squares peeled off from the functional layer surface of the polarizer protective film was visually counted, and the function expressed by the following formula The adhesion between the layer and the substrate film was determined. In addition, what peeled partially among squares was also counted as the square which peeled, and was ranked according to the following references | standards.
Adhesiveness (%) = (1−number of peeled squares / 100) × 100
A: 100% or functional layer material failure B: 99-90%
Δ: 89-70%
X: 69 to 0%
Examples 4 and 5 are anti-glare layers, Examples 6 and 7 are anti-glare antireflection layers, Examples 8 and 9 are low-reflection layers, In Examples 10 and 11, a hard coat layer was laminated and evaluated except that an antireflection layer was laminated and evaluated.

(11) Moist heat resistance The obtained polyester film for protecting a polarizer having a functional layer was boiled with water for 1 hour. Next, the polyester film for protecting the polarizer was taken out, wiped off moisture, and immediately evaluated for adhesion. Adhesive evaluation evaluated the adhesiveness of a functional layer and a polyester film by the method similar to said (10), and ranked according to the following reference | standard.
A: 100% or functional layer material failure B: 99-90%
Δ: 89-70%
X: 69 to 0%

(Polymerization of polyester resin used in easy-adhesion layer P1)
In a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux condenser, 194.2 parts by weight of dimethyl terephthalate, 184.5 parts by weight of dimethyl isophthalate, 14.8 parts by weight of dimethyl-5-sodium sulfoisophthalate, The mixture was charged with 233.5 parts by mass of diethylene glycol, 136.6 parts by mass of ethylene glycol, and 0.2 parts by mass of tetra-n-butyl titanate, and subjected to a transesterification reaction at a temperature of 160 to 220 ° C. over 4 hours. Next, the temperature was raised to 255 ° C., and the pressure of the reaction system was gradually reduced, followed by reaction for 1 hour 30 minutes under a reduced pressure of 30 Pa to obtain a copolymerized polyester resin (A-1). The obtained copolyester resin (A-1) was light yellow and transparent. It was 0.70 dl / g when the reduced viscosity of copolyester resin (A-1) was measured. The glass transition temperature by DSC was 40 ° C.

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

(Adjustment of polyester aqueous dispersion used in easy-adhesion layer P1)
30 parts by mass of polyester resin (A-1) and 15 parts by mass of ethylene glycol n-butyl ether were placed in a reactor equipped with a stirrer, a thermometer and a reflux device, and heated and stirred at 110 ° C. to dissolve the resin. After the resin was completely dissolved, 55 parts by mass of water was gradually added to the polyester solution while stirring. After the addition, the solution was cooled to room temperature while stirring to prepare a milky white polyester aqueous dispersion (Aw-1) having a solid content of 30% by mass. Similarly, using the polyester resins (A-2) to (A-5) instead of the polyester resin (A-1), water dispersions are prepared, and the polyester water dispersions (Aw-2) to (Aw) are respectively produced. -5).

(Adjustment of aqueous polyvinyl alcohol solution used in the easy adhesion layer P1)
In a container equipped with a stirrer and a thermometer, 90 parts by mass of water was added, and 10 parts by mass of polyvinyl alcohol resin (manufactured by Kuraray) (B-1) having a polymerization degree of 500 was gradually added while stirring. After the addition, the solution was heated to 95 ° C. while stirring to dissolve the resin. After dissolution, the mixture was cooled to room temperature with stirring to prepare a polyvinyl alcohol aqueous solution (Bw-1) having a solid content of 10% by mass. Similarly, polyvinyl alcohol resins (B-2) to (B-7) were used instead of the polyvinyl alcohol resin (B-1) to prepare aqueous solutions, which were designated as (Bw-2) to (Bw-7), respectively. . Table 2 shows the degree of saponification of the polyvinyl alcohol resins (B-1) to (B-7).

(Polymerization of block polyisocyanate crosslinking agent used in easy-adhesion layer P1)
In a flask equipped with a stirrer, a thermometer, and a reflux condenser, 100 parts by mass of a polyisocyanate compound having an isocyanurate structure using hexamethylene diisocyanate as a raw material (manufactured by Asahi Kasei Chemicals, Duranate TPA), 55 parts by mass of propylene glycol monomethyl ether acetate, polyethylene 30 parts by mass of glycol monomethyl ether (average molecular weight 750) was charged, and kept at 70 ° C. for 4 hours under a nitrogen atmosphere. Thereafter, the reaction solution temperature was lowered to 50 ° C., and 47 parts by mass of methyl ethyl ketoxime was added dropwise. The infrared spectrum of the reaction solution was measured to confirm that the absorption of the isocyanate group had disappeared, and a block polyisocyanate aqueous dispersion (C-1) having a solid content of 75% by mass was obtained.

(Polymerization of urethane resin D-1 used in easy-adhesion layer P2)
A urethane resin D-1 having an aliphatic polycarbonate polyol as a constituent component was prepared by the following procedure. In a four-necked flask equipped with a stirrer, Dimroth cooler, nitrogen inlet tube, silica gel drying tube, and thermometer, 43.75 parts by mass of 4,4-diphenylmethane diisocyanate, 12.85 parts by mass of dimethylolbutanoic acid, several 153.41 parts by mass of polyhexamethylene carbonate diol having an average molecular weight of 2000, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent were added and stirred at 75 ° C. for 3 hours in a nitrogen atmosphere. It was confirmed that had reached the predetermined amine equivalent. Next, after the temperature of this reaction liquid was lowered to 40 ° C., 8.77 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 g of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring and adjusted to 25 ° C., while stirring and mixing at 2000 min ⁻¹ , the polyurethane prepolymer solution was added and dispersed in water. . Thereafter, a part of acetone and water was removed under reduced pressure to prepare a water-soluble polyurethane resin (D-1) having a solid content of 35%. The glass transition temperature of the polyurethane resin (D-1) containing the obtained aliphatic polycarbonate polyol as a constituent component was −30 ° C.

(Polymerization of urethane resin D-2 used in easy adhesion layer P2)
A urethane resin D-2 containing an aliphatic polycarbonate polyol as a constituent component was prepared by the following procedure. In a four-necked flask equipped with a stirrer, a Dimroth cooler, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 29.14 parts by mass of 4,4-diphenylmethane diisocyanate, 7.57 parts by mass of dimethylolbutanoic acid, several An average molecular weight of 3000 polyhexamethylene carbonate diol 173.29 parts by mass, dibutyltin dilaurate 0.03 parts by mass, and 84.00 parts by mass of acetone as a solvent were added, and the mixture was stirred at 75 ° C. for 3 hours in a nitrogen atmosphere. It was confirmed that had reached the predetermined amine equivalent. Next, after the temperature of this reaction liquid was lowered to 40 ° C., 5.17 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 g of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring and adjusted to 25 ° C., while stirring and mixing at 2000 min ⁻¹ , the polyurethane prepolymer solution was added and dispersed in water. . Thereafter, a part of acetone and water was removed under reduced pressure to prepare a water-soluble polyurethane resin (D-2) having a solid content of 35%.

(Polymerization of urethane resin D-3 used in easy adhesion layer P2)
A urethane resin D-3 containing an aliphatic polycarbonate polyol as a constituent component was prepared by the following procedure. In a four-necked flask equipped with a stirrer, Dimroth cooler, nitrogen inlet tube, silica gel drying tube, and thermometer, 43.75 parts by mass of 4,4-diphenylmethane diisocyanate, 11.12 parts by mass of dimethylolbutanoic acid, hexane 1.97 parts by mass of diol, 143.40 parts by mass of polyhexamethylene carbonate diol having a number average molecular weight of 2000, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent were added, and 75 ° C. in a nitrogen atmosphere. The mixture was stirred for 3 hours to confirm that the reaction solution reached a predetermined amine equivalent. Next, after the temperature of this reaction liquid was lowered to 40 ° C., 8.77 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 g of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring and adjusted to 25 ° C., while stirring and mixing at 2000 min ⁻¹ , the polyurethane prepolymer solution was added and dispersed in water. . Thereafter, a part of acetone and water was removed under reduced pressure to prepare a water-soluble polyurethane resin (D-3) having a solid content of 35%.

(Polymerization of urethane resin D-4 used in easy-adhesion layer P2)
A silanol group-containing urethane resin D-4 containing an aliphatic polycarbonate polyol as a constituent component was prepared by the following procedure. In a four-necked flask equipped with a stirrer, a Dimroth cooler, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 38.41 parts by mass of isophorone diisocyanate, 6.95 parts by mass of dimethylolpropanoic acid, and a number average molecular weight of 2000 Polyhexamethylene carbonate diol 158.999 parts by mass, dibutyltin dilaurate 0.03 parts by mass, and acetone 84.00 parts by mass as a solvent were added and stirred at 75 ° C. for 3 hours in a nitrogen atmosphere. It was confirmed that the equivalent amount was reached. Next, after cooling this reaction liquid to 40 degreeC, 4.37 mass parts of triethylamine was added, and the polyurethane prepolymer solution was obtained. Next, 3.84 parts by mass of γ- (aminoethyl) aminopropyltriethoxysilane, 1.80 parts by mass of 2-[(2-aminoethyl) amino] ethanol and 450 g of water were added, and the polyurethane prepolymer solution was dropped. And dispersed in water. Thereafter, a part of acetone and water was removed under reduced pressure to prepare a water-soluble silanol group-containing polyurethane resin (D-4) having a solid content of 30%.

(Polymerization of urethane resin D-5 used for easy adhesion layer P2)
A urethane resin D-5 containing an aliphatic polycarbonate polyol as a constituent component was prepared by the following procedure. A water-soluble polyurethane resin having a solid content of 35% was obtained in the same manner except that the polyhexamethylene carbonate diol having a number average molecular weight of 2000 in the water-soluble polyurethane resin (D-1) was changed to a polyhexamethylene carbonate diol having a number average molecular weight of 1000. (D-5) was obtained.

(Polymerization of urethane resin D-6 used in easy-adhesion layer P2)
A urethane resin D-6 containing an aliphatic polycarbonate polyol as a constituent component was prepared by the following procedure. A water-soluble polyurethane resin having a solid content of 35% was obtained in the same manner except that the polyhexamethylene carbonate diol having a number average molecular weight of 2000 in the water-soluble polyurethane resin (D-1) was changed to a polyhexamethylene carbonate diol having a number average molecular weight of 5000. (D-6) was obtained.

(Polymerization of urethane resin D-7 used for easy-adhesion layer P2)
Polymerization D-7 of urethane resin containing polyester polyol as a constituent component was prepared by the following procedure. A water-soluble polyurethane resin having a solid content of 35% (D-) was used in the same manner except that the polyhexamethylene carbonate diol having a number average molecular weight of 2000 of the water-soluble polyurethane resin (D-1) was changed to a polyester diol having a number average molecular weight of 2000. 7) was obtained.

(Polymerization polymerization of urethane resin D-8 used for easy adhesion layer P2)
Polymerization D-8 of a urethane resin containing polyether polyol as a constituent component was produced by the following procedure. A water-soluble polyurethane resin (D) having a solid content of 35% was obtained in the same manner except that the polyhexamethylene carbonate diol having a number average molecular weight of 2000 in the water-soluble polyurethane resin (D-1) was changed to a polyether diol having a number average molecular weight of 2000. -8) was obtained.

(Polymerization of block polyisocyanate crosslinking agent E-1 used in easy-adhesion layer P2)
100 parts by mass of a polyisocyanate compound having an isocyanurate structure using hexamethylene diisocyanate as a raw material (manufactured by Asahi Kasei Chemicals, Duranate TPA) in a flask equipped with a stirrer, a thermometer and a reflux condenser, 55 parts by mass of propylene glycol monomethyl ether acetate, 30 parts by mass of polyethylene glycol monomethyl ether (average molecular weight 750) was charged and held at 70 ° C. for 4 hours in a nitrogen atmosphere. Thereafter, the reaction solution temperature was lowered to 50 ° C., and 47 parts by mass of methyl ethyl ketoxime was added dropwise. The infrared spectrum of the reaction solution was measured to confirm that the absorption of the isocyanate group had disappeared, and a block polyisocyanate aqueous dispersion (E-1) having a solid content of 75% by mass was obtained.

(Polymerization of oxazoline-based crosslinking agent E-2 used in easy-adhesion layer P2)
A mixture of 58 parts by mass of ion-exchanged water and 58 parts by mass of isopropanol as an aqueous medium in a flask equipped with a thermometer, a nitrogen gas introduction tube, a reflux condenser, a dropping funnel, and a stirrer, and a polymerization initiator (2, 2 4 parts by mass of '-azobis (2-amidinopropane) dihydrochloride) was added. On the other hand, in a dropping funnel, 16 parts by mass of 2-isopropenyl-2-oxazoline as a polymerizable unsaturated monomer having an oxazoline group, methoxypolyethylene glycol acrylate (average number of moles of ethylene glycol added: 9 moles, Shin Nakamura Chemical) A mixture of 32 parts by mass and 32 parts by mass of methyl methacrylate was added, and the mixture was added dropwise at 70 ° C. for 1 hour in a nitrogen atmosphere. After completion of the dropwise addition, the reaction solution was stirred for 9 hours and cooled to obtain a water-soluble resin (E-2) having an oxazoline group having a solid concentration of 40% by mass.

(Polymerization of carbodiimide-based crosslinking agent E-3 used in easy-adhesion layer P2)
A flask equipped with a stirrer, thermometer and reflux condenser was charged with 168 parts by mass of hexamethylene diisocyanate and 220 parts by mass of polyethylene glycol monomethyl ether (M400, average molecular weight 400), stirred at 120 ° C. for 1 hour, 26 parts by mass of 4′-dicyclohexylmethane diisocyanate and 3.8 parts by mass of 3-methyl-1-phenyl-2-phospholene-1-oxide (2% by weight based on the total isocyanate) as a carbodiimidization catalyst were added, and 185 under a nitrogen stream. Stir at 5 ° C. for a further 5 hours. The infrared spectrum of the reaction solution was measured, and it was confirmed that absorption at a wavelength of 2200 to 2300 cm ⁻¹ disappeared. It stood to cool to 60 degreeC, 567 mass parts of ion-exchange water was added, and the carbodiimide water-soluble resin (E-3) of 40 mass% of solid content was obtained.

Formation of functional layer (formation of hard coat layer)
A hard coat layer-forming coating solution (H-1) having the following composition was applied to the surface of the easy-adhesion layer P2 provided on the polyester film produced in the examples described later using a # 10 wire bar, at 70 ° C. Dry for 1 minute to remove the solvent. Next, the film coated with the hard coat layer was irradiated with 300 mJ / cm ² ultraviolet rays using a high-pressure mercury lamp to obtain a polarizer protective polyester film having a hard coat layer with a thickness of 5 μm.
Hard coat layer forming coating solution (H-1)
Methyl ethyl ketone 65.00% by mass
Dipentaerythritol hexaacrylate 27.20% by mass
(Shin-Nakamura Chemical A-DPH)
Polyethylene diacrylate 6.80% by mass
(Shin-Nakamura Chemical A-400)
Photopolymerization initiator 1.00% by mass
(Irgacure 184 manufactured by Ciba Specialty Chemicals)

(Formation of antiglare layer)
The anti-glare layer-forming coating solution (H-2) having the following composition was applied to the surface of the easy-adhesion layer P2 provided on the polyester film produced in the examples described later using a bar coater, and at 70 ° C. for 1 minute. Dry and remove the solvent. Next, the film on which the antiglare layer was applied was irradiated with 300 mJ / cm ² of ultraviolet light using a high pressure mercury lamp to obtain a polyester film for protecting a polarizer having an antiglare layer having a thickness of 5 μm.
Coating solution for forming antiglare layer (H-2)
Toluene 34 parts by weight Pentaerythritol triacrylate 50 parts by weight
Silica (average particle size 1 μm) 12 parts by weight
Silicone (leveling agent) 1 part by weight Photopolymerization initiator 1 part by weight (Irgacure 184 manufactured by Ciba Specialty Chemicals)

(Formation of antiglare antireflection layer)
After forming the antiglare layer (H-2), a low refractive index layer-forming coating solution (H-3) having the following composition is applied onto the antiglare layer using a bar coater and dried at 60 ° C. Then, 300 mJ / cm ² of ultraviolet light was irradiated using a high-pressure mercury lamp, and further heated at 120 ° C. for 5 minutes to obtain a polyester film for protecting a polarizer having a low refractive index layer having a thickness of 0.1 μm.
Coating liquid for forming a low refractive index layer (H-3)
Fluoropolymer-containing photocurable resin 25.00% by mass
(Opstar TM501A, solid content 15%, manufactured by JSR Corporation)
Silica particles 1.40% by mass
(MIBK-ST, solid content 30%, manufactured by Nissan Chemical)
Methyl isobutyl ketone 73.60% by mass

(Formation of low reflection layer)
A coating liquid for forming a low reflection layer (H-4) having the following composition was applied to the surface of the easy-adhesion layer P2 provided on the polyester film produced in the examples described later using a bar coater, and then at 70 ° C. for 1 minute. Dry and remove the solvent. Next, the film coated with the low reflection layer was irradiated with 400 mJ / cm ² of ultraviolet light using a high pressure mercury lamp to obtain a polyester film for protecting a polarizer having a low reflection layer having a thickness of 0.14 μm.
Low reflective layer forming coating solution (H-4)
Hollow silica fine particles 60 parts by mass Dipentaerythritol hexaacrylate 40 parts by mass Photopolymerization initiator 2 parts by mass (Ciba Specialty Chemicals Co., Ltd., Irgacure 907)
Isopropyl alcohol 2000 parts by mass

(Formation of antireflection layer)
A medium refractive index layer forming coating solution (H-5) having the following composition was applied to the surface of the easy-adhesion layer P2 provided on the polyester film produced in the examples described later using a bar coater, and 70 ° C. for 1 minute. After drying, ultraviolet rays of 400 mJ / cm ² were irradiated using a high-pressure mercury lamp to obtain a medium refractive index layer having a dry film thickness of 5 μm. Next, a coating solution for forming a high refractive index layer (H-6) having the following composition is formed on the formed middle refractive index layer by the same method as that for the middle refractive index layer using a bar coater. A low-refractive-index layer-forming coating solution (H-7) having the following composition was formed thereon by the same method as that for the middle-refractive index layer to obtain a polarizer-protecting polyester film on which an antireflection layer was laminated.
Medium refractive index layer coating solution (H-5) (refractive index 1.52)
Dipentaerythritol hexaacrylate 70 parts by weight 1,6-bis (3-acryloyloxy-2-hydroxypropyloxy) hexane
30 parts by weight photopolymerization initiator 4 parts by weight (manufactured by Ciba Specialty Chemicals Co., Ltd., Irgacure 184)
Isopropanol 100 parts by weight High refractive index layer forming coating solution (H-6) (refractive index 1.64)
ITO fine particles (average particle size 0.07 μm) 85 parts by weight tetramethylol methane triacrylate 15 parts by weight photopolymerization initiator (KAYACURE BMS, manufactured by Nippon Kayaku) 5 parts by weight butyl alcohol 900 parts by weight Low refractive index layer forming coating solution (H-7) (refractive index 1.42)
1,10-Diacryloyloxy-2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluorodecane 70 parts by weight Dipentaerythritol Hexaacrylate 10 parts by weight Silica gel fine particles (XBA-ST, manufactured by Nissan Chemical) 60 parts by weight Photopolymerization initiator (KAYACURE BMS, manufactured by Nippon Kayaku) 5 parts by weight

Example 1
(1) Preparation of coating solution for easy adhesion layer P1 The following coating agent was mixed to prepare a coating solution in which the mass ratio of polyester resin (A) / polyvinyl alcohol resin (B) was 70/30. The polyester aqueous dispersion uses an aqueous dispersion (Aw-1) in which a polyester resin having an acid value of 2 KOH mg / g is dispersed, and the polyvinyl alcohol aqueous solution is an aqueous solution in which polyvinyl alcohol having a saponification degree of 74 mol% is dissolved. (Bw-4) was used.
Water 40.61 mass%
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 11.67 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 15.00 mass%
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

(2) Preparation of coating solution for easy-adhesion layer P2 The following coating agent was mixed to prepare a coating solution for forming a coating layer having excellent adhesion to the hard coat layer.
Water 55.62% by mass
Isopropanol 30.00% by mass
Polyurethane resin (D-1) 11.29 mass%
Block polyisocyanate aqueous dispersion (E-1) 2.26 mass%
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicon, solid content concentration of 100% by mass)

(2) Manufacture of polarizer protective polyester film PET resin pellet having intrinsic viscosity (solvent: phenol / tetrachloroethane = 60/40) of 0.62 dl / g as a film raw material polymer and containing substantially no particles Was dried at 135 ° C. under reduced pressure of 133 Pa for 6 hours. Thereafter, the sheet was supplied to an extruder, melted and extruded into a sheet at about 280 ° C., and rapidly cooled and solidified on a rotating cooling metal roll maintained at a surface temperature of 20 ° C. to obtain an unstretched PET sheet.

  This 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 difference in peripheral speed to obtain a uniaxially stretched PET film.

Subsequently, after apply | coating the coating liquid of the said easily bonding layers P1 and P2 to both surfaces of PET film by the roll coat method, it dried at 80 degreeC for 15 second. The coating amount 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. with a tenter, and heated at 230 ° C. for 0.5 seconds with the length in the width direction fixed, and further at 230 ° C. for 10 seconds. % Relaxation treatment in the width direction was performed to obtain a polarizer protective polyester film having a thickness of 38 μm. The evaluation results are shown in Table 3.

Example 2
A polyester film for protecting a polarizer in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P1 is changed to an aqueous dispersion (Aw-2) in which a polyester resin having an acid value of 4 KOHmg / g is dispersed. Got.

Example 3
A polyester film for protecting a polarizer in the same manner as in Example 1, except that the polyester aqueous dispersion of the easy adhesion layer P1 is changed to an aqueous dispersion (Aw-3) in which a polyester resin having an acid value of 6 KOHmg / g is dispersed. Got.

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-3) in which the saponification degree of polyvinyl alcohol was 79 mol%.

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) in which the saponification degree of polyvinyl alcohol in the easy-adhesion layer P1 was 83 mol% was used.

Example 6
Except for mixing the following coating agent and changing the mass ratio of the polyester resin (A) / polyvinyl alcohol resin (B) of the easy-adhesion layer P1 to 60/40, the same as in Example 1. A polyester film for protecting the polarizer was obtained.
Water 37.28% by mass
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 10.00 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 20.00 mass%
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 7
Except for mixing the following coating agent and changing the mass ratio of the polyester resin (A) / polyvinyl alcohol resin (B) of the easy-adhesion layer P1 to 80/20, the same as in Example 1. A polyester film for protecting the polarizer was obtained.
43.95% by weight of water
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 13.33 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 10.00 mass%
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 8
Except for mixing the following coating agent and changing the mass ratio of the polyester resin (A) / polyvinyl alcohol resin (B) of the easy-adhesion layer P1 to 50/50, the same as in Example 1. A polyester film for protecting the polarizer was obtained.
Water 33.95% by mass
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 8.33 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 25.00% by mass
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 9
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the composition of the coating solution for the easy adhesion layer P1 was changed as follows.
40.87% by mass of water
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 11.67 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 15.00 mass%
Melamine type crosslinking agent (C-2) 0.71 mass%
(Nikarak MX-042, manufactured by Sanwa Chemical Co., Ltd., solid content concentration 70%)
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 10
For protecting the polarizer in the same manner as in Example 1, except that the aqueous polyvinyl alcohol solution of the easy-adhesion layer P1 was changed to an aqueous solution (Bw-5) in which polyvinyl alcohol having a saponification degree of polyvinyl alcohol of 70 mol% was dissolved. A polyester film was obtained.

Example 11
For protecting the polarizer in the same manner as in Example 1 except that the polyvinyl alcohol aqueous solution of the easy-adhesion layer P1 was changed to an aqueous solution (Bw-6) in which polyvinyl alcohol having a saponification degree of polyvinyl alcohol of 67 mol% was dissolved. A polyester film was obtained.

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 solution for the easy adhesion layer P1 was changed as follows.
40.33% by mass of water
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 11.67 mass%
Polyvinyl alcohol aqueous solution (Bw-2) 15.00 mass%
Oxazoline-based crosslinking agent (C-3) 1.25% by mass
(Epocross WS-500, manufactured by Nippon Shokubai, solid concentration 40% by mass)
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 13
A polyester film for protecting a polarizer in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P1 is changed to an aqueous dispersion (Aw-5) in which a polyester resin having an acid value of 10 KOHmg / g is dispersed. Got.

Comparative Example 1
Except for mixing the following coating agent and changing the mass ratio of the polyester resin (A) / polyvinyl alcohol resin (B) of the easy-adhesion layer P1 to 100/0, the same as in Example 1. A polyester film for protecting the polarizer was obtained.
Water 50.62% by mass
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 16.66 mass%
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Comparative Example 2
Except for mixing the following coating agent and changing the mass ratio of the polyester resin (A) / polyvinyl alcohol resin (B) of the easy-adhesion layer P1 to 0/100, the same as in Example 1. A polyester film for protecting the polarizer was obtained.
17.28% by mass of water
Isopropanol 30.00% by mass
Polyvinyl alcohol aqueous solution (Bw-4) 50.00 mass%
Block isocyanate-based crosslinking agent (C-1) 0.67% by mass
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Catalyst (Organic tin compound, solid content concentration 14% by mass) 0.3% by mass
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Comparative Example 3
A polyester film for protecting a polarizer in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P1 is changed to an aqueous dispersion (Aw-4) in which a polyester resin having an acid value of 25 KOHmg / g is dispersed. Got.

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 of the easy adhesion layer P1 was changed to an aqueous solution (Bw-1) in which polyvinyl alcohol having a saponification degree of 88 mol% was dissolved. Obtained.

Comparative 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 of the easy-adhesion layer P1 was changed to an aqueous solution (Bw-7) in which polyvinyl alcohol having a saponification degree of 40 mol% was dissolved. Obtained.

Comparative Example 6
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the following coating agent was mixed and the crosslinking agent was not mixed with the easy-adhesion layer P1.
41.58% by mass of water
Isopropanol 30.00% by mass
Polyester water dispersion (Aw-1) 11.67 mass%
Polyvinyl alcohol aqueous solution (Bw-4) 15.00 mass%
1.25% by mass of particles
(Silica sol with an average particle size of 100 nm, solid content concentration of 40% by mass)
Surfactant 0.5% by mass
(Silicone, solid content concentration 10% by mass)

Example 14
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyurethane resin (D-1) of the easy adhesion layer P2 was changed to the polyurethane resin (D-5).

Example 15
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyurethane resin (D-1) of the easy adhesion layer P2 was changed to the polyurethane resin (D-6).

Comparative Example 7
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyurethane resin (D-1) of the easy adhesion layer P2 was changed to the polyurethane resin (D-7).

Comparative Example 8
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyurethane resin (D-1) of the easy adhesion layer P2 was changed to the polyurethane resin (D-8).

Comparative Example 9
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution for the easy adhesion layer P2 was changed to the following.
Water 53.04 mass%
Isopropanol 30.00% by mass
Polyurethane resin (D-1) 16.13 mass%
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicon, solid content concentration of 100% by mass)

Example 16
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution for the easy adhesion layer P2 was changed to the following.
Water 53.91% by mass
Isopropanol 30.00% by mass
Polyurethane resin (D-1) 14.51% by mass
Block polyisocyanate aqueous dispersion (E-1) 0.75 mass%
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicon, solid content concentration of 100% by mass)

Example 17
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution for the easy adhesion layer P2 was changed to the following.
Water 54.76% by mass
Isopropanol 30.00% by mass
Polyurethane resin (D-1) 12.90 mass%
Block polyisocyanate aqueous dispersion (E-1) 1.51% by mass
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicon, solid content concentration of 100% by mass)

Example 18
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution for the easy adhesion layer P2 was changed to the following.
Water 57.35% by mass
Isopropanol 30.00% by mass
Polyurethane resin (D-1) 8.06% by mass
Block polyisocyanate aqueous dispersion (E-1) 3.76% by mass
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicon, solid content concentration of 100% by mass)

Example 19
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution for the easy adhesion layer P2 was changed to the following.
59.92% by mass of water
Isopropanol 30.00% by mass
Polyurethane resin (D-1) 3.23 mass%
Block polyisocyanate aqueous dispersion (E-1) 6.02 mass%
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicon, solid content concentration of 100% by mass)

Example 20
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution for the easy adhesion layer P2 was changed to the following.
60.79% by mass of water
Isopropanol 30.00% by mass
Polyurethane resin (D-1) 1.61% by mass
Block polyisocyanate aqueous dispersion (E-1) 6.77 mass%
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicon, solid content concentration of 100% by mass)

Example 21
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyurethane resin (D-1) of the easy adhesion layer P2 was changed to the polyurethane resin (D-2).

Example 22
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyurethane resin (D-1) of the easy adhesion layer P2 was changed to the polyurethane resin (D-3).

Example 23
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyurethane resin (D-1) of the easy adhesion layer P2 was changed to the polyurethane resin (D-4).

Example 24
A polyester film for protecting a polarizer in the same manner as in Example 1 except that the block isocyanate aqueous dispersion (E-1) is changed to a water-soluble resin (E-2) having an oxazoline group in the coating solution for the easy adhesion layer P2. Got.

Example 25
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the blocked isocyanate aqueous dispersion (E-1) was changed to a carbodiimide water-soluble resin (E-3) in the coating solution for the easy adhesion layer P2. .

Example 26
Polarized light in the same manner as in Example 1 except that the block isocyanate aqueous dispersion (E-1) was changed to imino-methylolmelamine (solid content concentration 70% by weight) (E-4) in the coating solution for the easy adhesion layer P2. A polyester film for protecting a child was obtained.

Example 27
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution for the easy adhesion layer P2 was changed to the following.
62.82% by mass of water
Isopropanol 30.00% by mass
Polyurethane resin (D-1) 5.64% by mass
Block polyisocyanate aqueous dispersion (E-1) 1.13% by mass
0.35% by mass of particles
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.04% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.02% by mass
(Silicon, solid content concentration of 100% by mass)

Reference example 1
The result of having performed the said adhesive test using the TAC film (The Fuji Film Co., Ltd. product, thickness 80micrometer, saponification-processed) is shown as a film for polarizer protection.

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

Claims (10)

A polyester film for protecting a polarizer having an easy adhesion layer P1 on one side of the polyester film and an easy adhesion layer P2 on the other side,
The easy adhesion layer P1 contains a polyester resin (A), a polyvinyl alcohol resin (B), and a crosslinking agent (C).
The acid value of the polyester resin (A) is 20 KOHmg / g or less,
The saponification degree of the polyvinyl alcohol-based resin (B) is 60 to 85 mol%,
A polyester film for protecting a polarizer, wherein the easy adhesion layer P2 contains a urethane resin (D) and a crosslinking agent (E) containing aliphatic polycarbonate polyol as constituent components.   The polyester film for protecting a polarizer according to claim 1, wherein the polyester resin (A) contains a 5-sulfoisophthalic acid component in an amount of 1 to 15 mol% in the dicarboxylic acid component.   The polyester film for protecting a polarizer according to claim 1 or 2, wherein the crosslinking agent (C) is an isocyanate compound or a melamine compound. The mass ratio of the polyester resin (A), the polyvinyl alcohol resin (B), and the crosslinking agent (C) in the easy adhesion layer P1 satisfies the following formula. Polyester film for protecting polarizers.
0.8 ≦ (A) / (B) ≦ 5
2 ≦ ((A) + (B)) / (C) ≦ 50 The ratio (A ₁₄₆₀ / A ₁₅₃₀ ) of the absorbance (A ₁₄₆₀ ) near 1460 cm ⁻¹ derived from the aliphatic polycarbonate component of the polyurethane resin (D) and the absorbance (A ₁₅₃₀ ) near 1530 cm ⁻¹ derived from the urethane component is The polyester film for protecting a polarizer according to any one of claims 1 to 4, which is 0.40 to 1.55. The said crosslinking agent (E) is at least 1 sort (s) selected from the group which consists of a melamine type crosslinking agent, an isocyanate type crosslinking agent, a carbodiimide type crosslinking agent, and an oxazoline type crosslinking agent in any one of Claims 1-5. The polyester film for polarizer protection of description. The polyester film for polarizer protection in any one of Claims 1-6 whose mass ratio (D / E) of a urethane resin (D) and a crosslinking agent (E) is 1 / 9-9 / 1. Having at least one functional layer selected from the group consisting of a hard coat layer, an antiglare layer, an antiglare antireflection layer, an antireflection layer and a low reflection layer on the easily adhesive layer P2 of the polyester film for protecting the polarizer. A polyester film for protecting a polarizer according to any one of claims 1 to 7. A polarizing plate having a polarizer protective film on both sides of a polarizer,
The polarizing plate whose polarizer protective film of an at least one surface is a polyester film for polarizer protection in any one of Claims 1-8. A liquid crystal display device comprising at least one polarizing plate according to claim 9.