JP6142480B2 - Polyester film for polarizer protection - Google Patents

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 is 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. In addition, the present invention is excellent in suppression of interference spots when a functional layer such as a hard coat layer is laminated on a polyester film for protecting a polarizer, and has excellent adhesion with a functional layer such as a hard coat layer and under high temperature and high humidity. It aims at providing the polarizer protective film which is excellent in adhesiveness (moisture-heat resistance).

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 provide a coating layer containing polyester resin (X) containing naphthalenedicarboxylic acid as an acid component and particles on the surface of the polyester film on the side opposite to the above-described layer of knowledge. Therefore, it is excellent in suppressing interference spots when a functional layer such as a hard coat layer is laminated, and excellent in adhesion with a functional layer such as a hard coat layer and in high temperature and high humidity (moisture heat resistance). I found.
Based on these findings, the present inventors have made further studies and considerations, and have invented the present invention.

That is, a typical present invention is as follows.
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,
The easy adhesion layer P1 contains a polyester resin (A), a polyvinyl alcohol resin (B), and a crosslinking agent (C).
The polyester resin (A) contains a 5-sulfoisophthalic acid component in a dicarboxylic acid component in an amount of 1 to 15 mol%,
The crosslinking agent (C) is an isocyanate compound or a melamine compound,
The acid value of the polyester resin (A) is 20 KOHmg / g or less,
The saponification degree of the polyvinyl alcohol-based resin (B) is 60 to 85 mol%,
The easy-adhesion layer P2 contains a polyester resin (X) containing naphthalenedicarboxylic acid as an acid component and particles, and the particles are metal oxides having a refractive index of 1.7 to 3.0.
A polyester film for protecting a polarizer, wherein 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.
0.8 ≦ (A) / (B) ≦ 5
10 ≦ ((A) + (B)) / (C) ≦ 30
Item 2 .
The easy-adhesion layer P2 includes at least one crosslinking agent selected from the group consisting of a urea crosslinking agent, an epoxy crosslinking agent, a melamine crosslinking agent, an isocyanate crosslinking agent, an oxazoline crosslinking agent, and a carbodiimide crosslinking agent. The polyester film for protecting a polarizer according to Item 1, further comprising:
Item 3 .
One or more functional layers 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 are provided on the easily adhesive layer P2 of the polyester film for protecting the polarizer. Item 3. The polyester film for protecting a polarizer according to Item 1 or 2 , wherein:
Item 4 .
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 claim | item 1 -3 .
Item 5 .
Item 5. A liquid crystal display device comprising at least one polarizing plate according to item 4 .

  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. Further, the polyester film for protecting a polarizer of the present invention is excellent in suppression of interference spots when a functional layer such as a hard coat layer is laminated on the easy-adhesion layer P2, and has adhesion with a functional layer such as a hard coat layer and Excellent adhesion under high temperature and high humidity (moisture and heat resistance). Therefore, the polyester film of the present invention can be suitably used as a protective film for a polarizer. In another preferable embodiment, the polyester film for protecting a polarizer of the present invention is excellent in abrasion resistance. 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, but for example, polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; 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 crosslinked. 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.

  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 layer P1. Examples of the particles contained in the easy-adhesion layer in the present invention include titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay and the like, or a mixture thereof. Inorganic particles such as calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, calcium fluoride and other inorganic particles, styrene-based, acrylic-based, melamine-based, benzoguanamine-based, silicone-based Examples include organic polymer particles.

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

  In the present invention, the thickness of the easy-adhesion layer P1 can be appropriately set in the range of 0.001 to 2.00 μm, but in the range of 0.01 to 1.00 μm 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.

3. Easy adhesive layer P2
In the polyester film for protecting a polarizer of the present invention, in order to improve adhesion to various functional layers, a polyester resin (X) containing naphthalenedicarboxylic acid as an acid component and a refractive index of 1.7 to 3.0. An easy adhesion layer P2 containing metal oxide particles (particle A) is laminated.

(1) Refractive index control of coating layer The refractive index of the easy-adhesion layer P2 of the polyester film for protecting a polarizer of the present invention is adjusted in the vicinity of the middle between the functional layer such as a hard coat layer and the base polyester film. Since the refractive index of the functional layer such as the hard coat layer varies depending on the composition of the resin used in the functional layer such as the hard coat layer, it is desirable to adjust the refractive index of the easy-adhesion layer accordingly. It is preferable to adjust the refractive index of the easy-adhesion layer in the range of 1.6 to 1.7. By doing in this way, each interface refractive index difference is made small and interference spots are suppressed. In general, a coating layer having easy adhesion has a low refractive index (around 1.50). Therefore, in order to control the refractive index of the easy bonding layer P2 within the above range, in this application, naphthalenedicarboxylic acid is included in the coating layer as an acid component. Polyester resin (X) is used, and metal oxide particles (particle A) having a refractive index of 1.7 or more and 3.0 or less are further added. With such a configuration, an easy-adhesion layer having a high refractive index can be obtained while having adhesion. Details of these compositions will be described later.

(2) Particles having an average particle diameter of 200 nm to 700 nm (Particle B)
Since particles having an average particle size of 200 nm or more and 700 nm or less (particles B) are added to the easy adhesion layer, the effect of suppressing interference spots can be obtained. Therefore, it is preferable to add the particles B to the easy adhesion layer. The reason why the particles B have such an effect is that irregularities are formed at the interface between the easy adhesion layer and the functional layer such as a hard coat layer by adding particles having a relatively large average particle diameter to the coating layer. . Such an uneven structure causes light scattering at the interface between the easy adhesion layer and the functional layer such as the hard coat layer. It is considered that such random light scattering causes a disorder in the phase of the reflected light generated at the interface between the easy-adhesion layer and the base polyester film, resulting in an effect of suppressing interference spots. Unlike the prior art, it is not necessary to control the coating thickness to a high degree, and a coating liquid for forming a hard coat layer composed of various solvents can be applied in a wide range.

  Further, when the particle B is added to the easy-adhesion layer, the adhesion with a functional layer such as a hard coat layer is improved. This is because the formation of irregularities at the interface between the easy adhesion layer and the functional layer such as the hard coat layer increases the interface area between the easy adhesion layer and the functional layer such as the hard coat layer, which is advantageous for adhesion. It is thought that it acted on.

  In order for the particle B to exhibit the above-described effects, the thickness of the easy adhesion layer is preferably smaller than the average particle diameter of the particle B, and the thickness of the easy adhesion layer is preferably less than 1/1 of the average particle diameter of the particle B. / 2 or less is more preferable. Moreover, 1/15 or more of the average particle diameter of the particle | grains B is preferable, as for the thickness of an easily bonding layer, 1/10 or more is more preferable, and 1/7 or more is further more preferable. When the thickness of the easy adhesion layer is less than 1/15 of the average particle diameter of the particles B, the transparency may be lowered.

(3) Polyester resin containing a long-chain dicarboxylic acid component and / or a diol component The easy-adhesion layer uses a relatively hard polyester resin containing a naphthalenedicarboxylic acid component as described above, but has an average particle size of 200 nm to 700 nm. When the following relatively large particles are used, it is considered that if the line speed in the post-processing is increased by improving the productivity efficiency, the coating layer may be scraped or the particles may fall off. In that case, the outstanding abrasion resistance of an easily bonding layer is obtained by further using a long-chain dicarboxylic acid component and / or a diol component as a component of the polyester resin.

That is, the polyester resin used for the easy-adhesion layer of the present invention comprises naphthalene dicarboxylic acid as an acid component, and a dicarboxylic acid component represented by the following formula (1) and / or a diol component represented by the following formula (2). It is preferable to include.
(1) HOOC- (CH ₂ ) n —COOH (where n is an integer of 4 ≦ n ≦ 10)
(2) HO— (CH ₂ ) n —OH (where n is an integer of 4 ≦ n ≦ 10)

  Thus, by including an acid component and / or a diol component having a carbon component of a specific length, the polyester resin is given flexibility, and even relatively large particles can be easily held and easily adhered. It is possible to remarkably suppress layer scraping and particle dropping. On the other hand, if n is less than 4, such an effect cannot be obtained, and the easily adhesive layer may be scraped. Moreover, when n exceeds 10, the refractive index which a polyester resin show | plays will fall, and the suppression effect of the iris-like color under a fluorescent lamp may become inadequate. The upper limit of n is more preferably 9 or less, and further preferably 8 or less.

  Here, the abrasion resistance of the easy-adhesion layer can be measured by a measurement method described later. That is, in the abrasion resistance test of the easy-adhesion layer described later, it is preferably not more than the extent that powder can be slightly confirmed depending on the location on the black mount, and more preferably powder cannot be confirmed on the black mount (that is, In other words, there is no powder falling off in the abrasion resistance test of the easy-adhesion layer described later). The degree of powder falling can be confirmed by visual observation, fluorescent X-ray analysis, XMA, ESCA or the like. Here, “no powder fall-off” means that when the powder is inorganic particles, more specifically, the inorganic particles on the mount are below the detection limit in the fluorescent X-ray analysis.

  The present invention controls the iris color under a fluorescent lamp while maintaining the adhesion with a functional layer such as a hard coat layer and the adhesion under high temperature and high humidity (moisture and heat resistance). Can do. Moreover, in a preferable aspect, it has the abrasion resistance of the outstanding easily bonding layer. Further, the configuration of the present invention will be described in detail below.

  By including naphthalenedicarboxylic acid as an acid component of the polyester resin (X) contained in the easy-adhesion layer P2, the refractive index increases, and the iris color under a fluorescent lamp can be easily controlled. Moreover, it becomes possible to improve heat-and-moisture resistance.

  As such naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid is preferable. The proportion of the naphthalenedicarboxylic acid in the polyester resin (X) is preferably 20 mol% or more, more preferably 30 mol% or more, further preferably 50 mol% or more, and still more preferably 60 mol% or more as the acid component. Moreover, 90 mol% or less is preferable as an acid component, the ratio of the said naphthalene dicarboxylic acid in polyester resin (X) is more preferable, 85 mol% or less is more preferable, and 80 mol% or less is more preferable. The proportion of the naphthalenedicarboxylic acid in the polyester resin (X) is appropriately adjusted so that the refractive index of the easy-adhesion layer is within the above-mentioned range together with the particles A, but if the amount is less than 20 mol%, the amount of particles A added is large. The adhesion may be reduced. Moreover, when it exceeds 90 mol%, the adhesiveness of resin may fall.

Furthermore, the polyester resin (X) preferably contains a dicarboxylic acid component represented by the following formula (1) and / or a diol component represented by the following formula (2) in addition to naphthalenedicarboxylic acid as an acid component. The dicarboxylic acid component of the following formula (1) and / or the diol component of the following formula (2) in the polyester resin (X) is preferably 10 mol% or more, more preferably 15 mol% or more, and further preferably 20 mol% or more. preferable. Further, the dicarboxylic acid component of the following formula (1) and / or the diol component of the following formula (2) in the polyester resin (X) is preferably 70 mol% or less, more preferably 60 mol% or less, and more preferably 50 mol% or less. Is more preferable. If the dicarboxylic acid component of the following formula (1) and / or the diol component of the following formula (2) in the polyester resin is less than 10 mol%, the abrasion resistance of the easy-adhesion layer is deteriorated depending on the ratio of other components. In some cases, if it is 70 mol% or more, the refractive index decreases, and the effect of suppressing iris-like colors under a fluorescent lamp may be insufficient. In addition, about the structural component of a polyester resin, it can carry out suitably also by NMR and a mass spectrometer.
(1) HOOC- (CH ₂ ) n —COOH (where n is an integer of 4 ≦ n ≦ 10)
(2) HO— (CH ₂ ) n —OH (where n is an integer of 4 ≦ n ≦ 10)

  Examples of the dicarboxylic acid component of the formula (1) include adipic acid, sebacic acid, azelaic acid and the like. Examples of the diol component of the formula (2) include butanediol and hexanediol.

  The polyester resin (X) is water or a water-soluble organic solvent (eg, an aqueous solution containing less than 50% by mass of alcohol, alkyl cellosolve, ketone, or ether) or an organic solvent (eg, toluene, ethyl acetate, etc.) Those dissolved or dispersed in can be used.

  When the polyester resin (X) is used as an aqueous coating liquid, a water-soluble or water-dispersible polyester resin is used. For such water-solubilization or water-dispersion, a compound containing a sulfonate group is used. Alternatively, it is preferable to copolymerize a compound containing a carboxylate group.

  In addition, as long as the effect of the present invention is achieved, the acid component in the polyester resin (X) may further include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 1,4-cyclohexanedicarboxylic acid, trimellitic acid, Pyromellitic acid, dimer acid, 5-sodium sulfoisophthalic acid, 4-sodium sulfonaphthalene-2,7-dicarboxylic acid and the like may be used.

As long as the effects of the present invention are achieved, the diol component in the polyester resin (X) is further ethylene glycol, propane glycol, neopentyl glycol, diethylene glycol, 1,4-cyclohexanedimethanol, xylene glycol, ethylene of bisphenol A. Oxide adducts may be used.

  The polyester resin (X) is preferably contained in the easy-adhesion layer at a ratio of 30% by mass to 90% by mass in the total solid components. More preferably, it is 40% by mass or more and 80% by mass or less. When the content of the polyester resin (X) is large, the adhesion with a functional layer such as a hard coat layer under high temperature and high humidity decreases, and conversely, when the content is low, normal temperature, high temperature and high humidity. Adhesion with the lower polyester film is reduced.

  In order to form a crosslinked structure in the easy-adhesion layer, a crosslinking agent may be included. By containing a crosslinking agent, it becomes possible to further improve the adhesion under high temperature and high humidity. In addition, by introducing a cross-linked structure into the easy-adhesion layer, the solvent resistance against the coating solution solvent used when forming a functional layer such as a hard coat is improved, so that interference fringes are expressed due to variations in the thickness of the easy-adhesion layer. It can suppress more suitably. Examples of the crosslinking agent include urea, epoxy, melamine, isocyanate, oxazoline, carbodiimide, and the like. Among these, melamine-based, isocyanate-based, oxazoline-based, and carbodiimide-based are preferable from the viewpoints of stability of coating solution over time and improvement in adhesion under high-temperature and high-humidity treatment. Moreover, in order to promote a crosslinking reaction, a catalyst etc. are used suitably as needed.

  As content of the easily bonding layer of a crosslinking agent, 5 mass% or more and 50 mass% or less are preferable in all the solid components. More preferably, it is 10 mass% or more and 30 mass% or less. When the amount is small, the strength of the resin of the easy-adhesion layer decreases, and the adhesiveness 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 high humidity Adhesion at the bottom decreases.

It is preferable to contain metal oxide particles (particle A) having a refractive index of 1.7 or more and 3.0 or less in the easy adhesion layer. Examples of such metal oxides include TiO ₂ (refractive index 2.7), ZnO (refractive index 2.0), Sb ₂ O ₃ (refractive index 1.9), SnO ₂ (refractive index 2.1), ZrO ₂ (refractive index 2.4), Nb ₂ O ₅ (refractive index 2.3), CeO ₂ (refractive index 2.2), Ta ₂ O ₅ (refractive index 2.1), Y ₂ O ₃ (refractive) 1.8), La ₂ O ₃ (refractive index 1.9), In ₂ O ₃ (refractive index 2.0), Cr ₂ O ₃ (refractive index 2.5), etc., and including these metal atoms Examples include composite oxides. The easy adhesion layer contains at least one or two or more of these metal oxides. If the refractive index of the metal oxide particles is 1.7 or more, it is preferable in that the refractive index of the coating layer is adjusted within the above range. Moreover, if the refractive index of a metal oxide particle is 3.0 or less, it is preferable at the point which maintains the transparency of a film.

  The content of the metal oxide particles in the easy-adhesion layer is preferably controlled by the relationship between the refractive index of the metal oxide particles to be used and the refractive index of the hard coat layer to be applied. It is 2 mass% or more, More preferably, it is 5 mass% or more, and it is preferable that it is 70 mass% or less. As a minimum of content of metal oxide particles, 7 mass% or more is more preferred, and 8 mass% or more is still more preferred. Moreover, as an upper limit of content of a metal oxide particle, 50 mass% or less is more preferable, 30 mass% or less is more preferable, 20 mass% or less is further more preferable, 15 mass% or less is especially preferable. Depending on the refractive index of the functional layer such as a hard coat layer, metal oxide particles are added within the above range, and the refractive index of the easy-adhesion layer is in the range of 1.5 to 1.7, preferably 1.6 to 1. Adjust within the range of 7. If the content of the metal oxide particles is less than 2% by mass or less than 5% by mass, it may be difficult to adjust the refractive index of the easy-adhesion layer to the above range. Moreover, since the adhesiveness of an easily bonding layer may fall when content of a metal oxide particle exceeds 70 mass%, it is unpreferable. The average particle diameter of the metal oxide particles is not particularly limited, but is preferably 1 to 100 nm from the viewpoint of maintaining the transparency of the film.

  In the present invention, it is preferable to contain particles (particle B) having an average particle size of 200 nm or more and 700 nm or less in the easy-adhesion layer. Particles B include (1) silica, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, titanium dioxide, satin white, aluminum silicate Inorganic particles such as diatomaceous earth, calcium silicate, aluminum hydroxide, hydrous halloysite, magnesium carbonate, magnesium hydroxide, (2) acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene / acrylic, Styrene / butadiene, polystyrene / acrylic, polystyrene / isoprene, polystyrene / isoprene, methyl methacrylate / butyl methacrylate, melamine, polycarbonate, urea, epoxy, urethane, pheno System, diallyl phthalate, and organic particles of a polyester or the like.

  The particles (particles B) preferably have an average particle size of 200 to 700 nm. When the particle size is small, unevenness formation at the interface between the functional layer such as the easy-adhesion layer and the hard coat layer is small, the scattering effect is reduced, and the effect of suppressing the iris-like color under a fluorescent lamp may be insufficient. is there. If it is large, the transparency of the easy-adhesion layer may deteriorate.

  The particles (particles B) are preferably spherical particles that hardly aggregate. When the particles are aggregated, the effect of scattering is reduced, and not only the effect of suppressing the iris-like color under the lamp is likely to be insufficient, but also an optical defect may occur. In addition, spherical particles are preferable from the viewpoint of exhibiting the light scattering effect by the particles. Moreover, it is preferable that the particle | grains B are colorless and transparent from the point which maintains the transparency of a film.

  The average particle diameter of the particles in the easy-adhesion layer was measured by photographing a cross-section of the easy-adhesion film at a magnification of 120,000 using a transmission electron microscope (TEM), and 10 or more existing in the cross-section of the easy-adhesion layer. It can be obtained by measuring the maximum diameter of the particles and calculating their average value. In that case, in order to remove foreign matter and particles A, it is preferable to obtain an average by selecting particles of 100 nm or more.

  As content in the easily bonding layer of particle | grains B, 0.5 mass% or more and 5 mass% or less are preferable in all the solid components. As an upper limit of content in the easily bonding layer of particle | grains B, 4 mass% or less is more preferable, 3 mass% or less is further more preferable, and 2 mass% or less is especially preferable. When the amount is small, the scattering effect is reduced, and the iris-like color suppression effect under a fluorescent lamp tends to be insufficient. When the amount is large, not only the transparency of the easy-adhesion layer is deteriorated but also the film strength is lowered.

  The easy-adhesion layer may contain a surfactant for the purpose of improving leveling properties during coating and defoaming the coating solution. The surfactant may be any of cationic, anionic and nonionic surfactants, but is preferably a silicon-based, acetylene glycol-based or fluorine-based surfactant. These surfactants are preferably contained in the easy-adhesion layer within a range that does not impair the effect of suppressing iris color under a fluorescent lamp and the adhesion.

  In order to impart other functionality to the easy-adhesion layer, various additives may be included within a range that does not impair the effect of suppressing iris color and adhesion under a fluorescent lamp. Examples of the additive include fluorescent dyes, fluorescent brighteners, plasticizers, ultraviolet absorbers, pigment dispersants, foam suppressors, antifoaming agents, preservatives, and the like.

  In the present invention, examples of the method for providing the easy-adhesion layer on the polyester film include a method of applying a coating liquid containing a solvent, particles and a resin to the polyester film and drying. Examples of the solvent include organic solvents such as toluene, water, and a mixed system of water and a water-soluble organic solvent. Preferably, water alone or a mixture of a water-soluble organic solvent and water is used from the viewpoint of environmental problems. preferable.

  At any stage of the film manufacturing process, a coating liquid can be applied to one side of a polyester film (for example, PET film) to form the easy-adhesion layer. The solid content concentration of the resin composition in the coating solution is preferably 2 to 35% by weight, particularly preferably 4 to 15% by weight.

In this invention, it is preferable that the thickness of the easily bonding layer finally obtained is 20-350 nm, and the coating amount after drying is 0.02-0.5 g / m < ² >. If the coating amount of the easy-adhesion layer is less than 0.02 g / m ² , not only the effect on adhesiveness is almost lost, but also the suppression of iris color under a fluorescent lamp tends to be insufficient. On the other hand, if the coating amount exceeds 0.5 g / m ² , the effect of suppressing iris-like colors under fluorescent lamps tends to be insufficient.

(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.

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, tetramethyltyrium 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 the said 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 laminated on the easy-adhesion layer P2 of the polyester film for protecting a polarizer of the present invention, a publicly known one can be used, forming an uneven shape on the polyester film, and scattering external light. This prevents the visibility from being reduced due to reflection of external light or reflection of images. 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 particles used for 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 having the antiglare layer of the present invention 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 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, and the anti-glare layer is formed on the easy-adhesion layer P2. 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 anti-glare layer by transferring an uneven shape by laminating, and a method of forming unevenness by nanoimprinting without containing the particles, and forming unevenness 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.

The low refractive index layer used for the antiglare antireflection layer can use a resin having a refractive index of 1.52 or less. 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 of the present invention 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 addition amount of the ultrafine filler is preferably 5 to 70% by mass of the total mass of the low refractive index layer, more preferably 10 to 50% by mass, and particularly preferably 15 to 30% by mass.

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 The antireflection layer to be laminated on the easy-adhesion layer P2 of the polyester film for protecting a polarizer of the present invention can be laminated using a known one. 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 of the present invention, a high refractive index layer, a low refractive index, and the like. A multilayer structure such as a structure in which layers are sequentially laminated is mentioned. 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, SiO2) 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-A 2010-72039, and JP-A 2010-256705 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). Production of Polyester Film for Protecting Polarizer The method for producing 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 not limited to this. .

  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 Toh Cello Co., Ltd.], “Nichigo Vinylon” [Nippon Synthetic Chemical Co., Ltd.] Commercial products such as “made” can be used. Examples of the dichroic material include iodine, a disazo compound, and a polymethine dye.

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

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

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.

EXAMPLES Next, although this invention is demonstrated in detail using an Example, a comparative example, and a reference example, this invention is not limited to a following example naturally. Here, Example 12 below is to be read as Reference Example 12. The evaluation method used in the present invention is as follows.

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

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

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

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

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

(6) PVA adhesiveness The thickness of the polyvinyl alcohol resin layer after drying a polyvinyl alcohol aqueous solution (PVA117 made by Kuraray) adjusted to a solid content concentration of 5% by mass on the surface of the easy-adhesion layer P1 of the polyester film for protecting a polarizer, It apply | coated with the wire bar so that it might become 2 micrometers, and it dried for 5 minutes at 70 degreeC. As the polyvinyl alcohol aqueous solution, a solution in which a red dye was added so as to facilitate the determination was used. The prepared evaluation target film was attached to a glass plate having a thickness of 5 mm to which a double-sided tape was attached, and the opposite surface of the evaluation target laminated film on which the polyvinyl alcohol resin layer was formed was attached to the double-sided tape. Next, 100 grid-like cuts that penetrated through the polyvinyl alcohol resin layer and reached the base film were made using a cutter guide with a gap interval of 2 mm. Next, an adhesive tape (Cello Tape (registered trademark) CT-24; 24 mm width, manufactured by Nichiban Co., Ltd.) was attached to the grid-shaped cut surface. The air remaining at the interface at the time of pasting was pressed with an eraser to bring it into close contact, and then the work of peeling off the adhesive tape vigorously vertically was performed once, five times and ten times. The number of squares on which the polyvinyl alcohol resin layer was not peeled was counted to determine PVA adhesion. That is, when the PVA layer was not peeled off at all, the PVA adhesion rate was 100, and when all the PVA layer was peeled off, the PVA adhesion rate was 0. In addition, what was partially peeled within one square was also included in the number of peeled.
(7) Intrinsic viscosity Based on JIS K7367-5, it measured at 30 degreeC using the mixed solvent of a phenol (60 mass%) and 1,1,2,2-tetrachloroethane (40 mass%) as a solvent.

(8) Refractive index The refractive index of the hard coat layer was measured using an Abbe refractometer based on JIS K 7142 for a film obtained by curing each resin used in the hard coat layer. The refractive index of the particles A is such that the particles A dried at 90 ° C. are suspended in various liquids of 25 ° C. having different refractive indexes, and the refractive index of the liquid in which the suspension looks most transparent is the Abbe refractive index. It was measured by a meter.

(9) Average particle diameter A sample of the polarizer protective film was embedded in a visible light curable resin (D-800, manufactured by JEOL Datum Co., Ltd.) and cured by exposure to visible light at room temperature. From the obtained embedding block, an ultrathin section having a thickness of about 70 to 100 nm was prepared using an ultramicrotome equipped with a diamond knife, and dyed in ruthenium tetroxide vapor for 30 minutes. The stained ultrathin section was observed with a transmission electron microscope (TEM 2010, manufactured by JEOL Ltd.) to observe the cross section of the film and photographed. The magnification of the photograph is appropriately set in the range of 10,000 to 100,000 times. In this embodiment, the enlargement magnification is 80,000 times (acceleration voltage 200 kv). When obtaining the average particle size of the particles B, 10 or more particles having a particle size of about 100 nm or more were selected from the electron micrograph, the maximum diameter of these particles was measured, and the average value was obtained.
This is to remove particles having a small particle diameter that are not clearly the particles B of the present application, such as particles A and foreign matters.

(10) Interference spot improvement (iris color)
On the easy-adhesion layer P2 of the polarizer protective polyester film obtained in each example, a hard coat layer was formed by the method described later.
A polyester film for protecting a polarizer having a hard coat layer was cut into an area of 10 cm (film width direction) × 15 cm (film longitudinal direction) to prepare a sample film. A black glossy tape (manufactured by Nitto Denko, vinyl tape No. 21; black) was attached to the surface of the obtained sample film opposite to the hard coat layer. This sample film has a hard coat surface as the top surface and a three-wavelength daylight white color (National Palook, FL 15EX-N 15W) as a light source. 60 cm, and an angle of 15 to 45 ° with respect to the perpendicular to the film surface).

The results of visual observation are ranked according to the following criteria. The observation is performed by five people who are familiar with the evaluation, and the highest rank is the evaluation rank. If two ranks have the same number, the center of the rank divided into three is adopted. For example, ◎ and ○ are 2 people each and △ is 1 person, ○ is ◎, ◎ is 1 person and ○ and △ are 2 people each, ○, ◎ and △ are 2 people each and ○ is 1 In the case of names, ○ is adopted.
◎: Iridescent colors are not observed even when observed from all angles. ○: Some iris colors are observed at some angles. △: Slightly iris colors are observed. X: Clear iris colors are observed. Be done

(11) Adhesiveness A hard coat layer was formed by the method described later on the easy-adhesion layer P2 of the polyester film for protecting a polarizer obtained in the examples.
Using a cutter guide with a gap interval of 2 mm, 100 polarizer-shaped cuts reaching the base film through the hard coat layer are made on the hard coat layer surface using a polarizer protective polyester film laminated with a hard coat layer. . 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, the cellophane adhesive tape was peeled off vertically from the hard coat layer surface of the hard coat layer laminated polarizer protective film, and the number of grids peeled off from the hard coat layer surface of the hard coat layer laminated polarizer protective film was visually counted. From the formula, the adhesion between the hard coat 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%
○: 99-90%
Δ: 90-70%
X: 69 to 0%
Examples 4 and 5 are antiglare layers instead of hard coat layers, Examples 6 and 7 are antiglare antireflection layers instead of hard coat layers, and Examples 8 and 9 are low antiglare layers instead of hard coat layers. In the reflection layer, Examples 10 and 11, an antireflection layer was formed on the surface of the easy-adhesion layer P2 of the polarizer protecting polyester film in place of the hard coat layer, and the adhesion was evaluated.

(12) Moist heat resistance The polarizer protective polyester film laminated with the hard coat layer was allowed to stand in an environment of 60 ° C. and 95 RH% for 500 hours in a high-temperature and high-humidity tank, and then allowed to stand at room temperature and humidity for 12 hours.
And the contact | adhesion adhesiveness of a hard-coat layer and a base film was calculated | required by the method similar to said (13), and it ranked according to the following reference | standard.
A: 100%
○: 99-90%
Δ: 90-70%
X: 69 to 0%
Examples 4 and 5 are antiglare layers instead of hard coat layers, Examples 6 and 7 are antiglare antireflection layers instead of hard coat layers, and Examples 8 and 9 are low antiglare layers instead of hard coat layers. In the reflective layer, Examples 10 and 11, an antireflection layer was formed on the surface of the easy-adhesion layer P2 of the polyester film for protecting the polarizer instead of the hard coat layer, and the wet heat resistance was evaluated.

(13) Scratch resistance of easy-adhesion layer P2 3 cm (film width direction) of the polarizer protective polyester film produced in Examples described later on a friction fastness tester (manufactured by Daiei Kagaku Seiki Seisakusho, RT-200) × An aluminum foil (thickness 80 μm, arithmetic average surface roughness 0.03 μm) was used for the contact portion of the load head (2 cm × 2 cm, 200 g) with a weight (300 g) attached and 20 cm (film longitudinal direction) and a weight (300 g). A 10 cm distance was reciprocated 10 times at a speed of 20 seconds per reciprocation. The sample film obtained was placed on a black mount and it was visually confirmed whether the powder had fallen.
A: No powder falling on the black mount.
○: Slight powder falling can be confirmed depending on the location on the black mount.
(Triangle | delta): The slight powder fall can be confirmed on the whole black mount.
X: Powder fall can be clearly confirmed on the black mount.

The arithmetic average surface roughness is a value measured under the following conditions using a non-contact surface shape measurement system (VertScan R550H-M100).
(Measurement condition)
・ Measurement mode: WAVE mode ・ Objective lens: 50 × ・ 0.5 × Tube lens ・ Measurement area 187 × 139 μm

(Polymerization of polyester resin used for 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 for 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 for 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 for 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 polyester resin used for easy adhesion layer P2)
In a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux condenser, 302.9 parts by mass of dimethyl 2,6-naphthalenedicarboxylate, 47.4 parts by mass of dimethyl-5-sodium sulfoisophthalate, ethylene glycol 198 .6 parts by mass, 1,6-hexanediol 118.2 parts by mass, and tetra-n-butyl titanate 0.4 parts by mass were charged and a transesterification reaction was performed from 160 ° C. to 220 ° C. over 4 hours. Furthermore, 121.4 parts by weight of sebacic acid was added to carry out the esterification reaction. Next, the temperature was raised to 255 ° C., and the reaction system was gradually reduced in pressure, and then reacted for 1 hour 30 minutes under a reduced pressure of 30 Pa to obtain a copolymerized polyester resin (X-1). The obtained copolyester resin was light yellow and transparent.

In the same manner, copolymer polyester resins (X-2) to (X-12) having different compositions were obtained.
Table 3 shows the results of the composition and weight average molecular weight measured by 1H-NMR for these copolyester resins.

(Preparation of aqueous dispersion of polyester used for easy adhesion layer P2)
In a reactor equipped with a stirrer, a thermometer and a reflux device, 20 parts by mass of polyester resin (X-1) and 15 parts by mass of ethylene glycol t-butyl ether were added and heated and stirred at 110 ° C. to dissolve the resin. After the resin was completely dissolved, 65 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 an aqueous dispersion (Y-1) of milky white polyester having a solid content of 20% by mass. Similarly, polyester resins (X-2) to (X-12) are used in place of the polyester resin (X-1) to prepare an aqueous dispersion, and the aqueous dispersions (Y-2) to (Y-12) are prepared. ).

(Polymerization of block polyisocyanate crosslinking agent used for 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, and it was confirmed that the absorption of the isocyanate group had disappeared. Thus, a block polyisocyanate aqueous dispersion (D-1) having a solid content of 75% by mass was obtained.

(Polymerization of oxazoline-based crosslinking agent used for 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 (D-2) having an oxazoline group having a solid concentration of 40% by mass.

(Polymerization of carbodiimide-based crosslinking agent used for 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. An 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 (D-3) with a solid content of 40 mass% 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 of ultraviolet light using a high pressure mercury lamp to obtain a hard coat layer laminated polarizer protective film having a thickness of 5 μm. The refractive index of the hard coat layer was 1.55.
Hard coat layer forming coating solution (H-1)
Isopropanol 48.47 mass%
Dipentaerythritol hexaacrylate 21.25% by mass
(Shin-Nakamura Chemical A-DPH)
Polyethylene diacrylate 5.67% by mass
(Shin-Nakamura Chemical A-400)
ZrO2 sol 23.61 mass%
(Nissan Chemical OZ-30M, solid content 30% by mass)
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.
Antiglare layer forming coating solution (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) Adjustment of coating liquid of easy-adhesion layer P2 The following coating agent was mixed and the coating liquid (Z-1) was created. Particle A is SnO ₂ having a refractive index of 2.1, and particle B is silica particles having an average primary particle size of about 500 nm.
Water 40.16% by mass
Isopropanol 30.00% by mass
Polyester aqueous dispersion (Y-1) 18.19 mass%
Block polyisocyanate aqueous dispersion (D-1) 2.08 mass%
Particle A 9.37 mass%
(Cerames S-8 manufactured by Taki Chemical Co., Ltd., solid content concentration 8% by mass)
Particle B 0.17% by mass
(Nippon Shokubai Co., Ltd. Sea Hoster KEW50, solid content concentration 15% by mass)
Silicon-based surfactant 0.03% by mass
(Solid content 100%)

(3) Manufacture of a polyester film for protecting a polarizer PET resin pellets having an 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 Tables 4 and 5.

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 particles B were removed from the easy-adhesion layer P2.

Example 15
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the particles B of the easy adhesion layer P2 were changed to silica particles having an average particle diameter of 100 nm (Snowtex ZL manufactured by Nissan Chemical Industries, Ltd., solid content concentration: 40% by mass). Obtained.

Example 16
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-11.

Example 17
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-12.

Example 18
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution (Z-1) for the easy adhesion layer P2 was changed to the following.
(Coating solution Z-1)
44.54% by mass of water
Isopropanol 30.00% by mass
Polyester aqueous dispersion (Y-1) 12.21% by mass
Block polyisocyanate aqueous dispersion (D-1) 3.67% by mass
Particle A 9.38 mass%
(Cerames S-8, manufactured by Taki Chemical Co., Ltd., solid content concentration 8% by mass)
Particle B 0.17% by mass
(Nippon Shokubai Co., Ltd. Sea Hoster KEW50, solid content concentration 15% by mass)
Silicon-based surfactant 0.03% by mass
(Solid concentration 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 (Z-1) for the easy adhesion layer P2 was changed to the following.
Water 37.29% by mass
Isopropanol 30.00% by mass
Polyester water dispersion (Y-1) 22.09 mass%
Block polyisocyanate aqueous dispersion (D-1) 1.04% by mass
Particle A 9.38 mass%
(Cerames S-8, manufactured by Taki Chemical Co., Ltd., solid content concentration 8% by mass)
Particle B 0.17% by mass
(Nippon Shokubai Co., Ltd. Sea Hoster KEW50, solid content concentration 15% by mass)
Silicon-based surfactant 0.03% by mass
(Solid concentration 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 (Z-1) for the easy adhesion layer P2 was changed to the following.
35.76% by weight of water
Isopropanol 30.00% by mass
Polyester aqueous dispersion (Y-1) 24.17% by mass
Block polyisocyanate aqueous dispersion (D-1) 0.49 mass%
Particle A 9.38 mass%
(Cerames S-8, manufactured by Taki Chemical Co., Ltd., solid content concentration 8% by mass)
Particle B 0.17% by mass
(Nippon Shokubai Co., Ltd. Sea Hoster KEW50, solid content concentration 15% by mass)
Silicon-based surfactant 0.03% by mass
(Solid concentration 100% by mass)

Example 21
A polyester film for protecting a polarizer in the same manner as in Example 1 except that the particles B of the easy-adhesion layer P2 were changed to silica particles having an average particle size of 230 nm (Quartron PL-20 manufactured by Fuso Chemical Industry, solid concentration 24 mass%). Got.

Example 22
A polyester film for protecting a polarizer in the same manner as in Example 1 except that the particles B of the easy-adhesion layer P2 are changed to acrylic particles having an average particle size of 300 nm (Gantz Kasei Ganzpearl PM-030, solid concentration 41% by mass). Got.

Example 23
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the particles B of the easy-adhesion layer P2 were changed to silica particles having an average particle diameter of 450 nm (MP4540M, Nissan Chemical Industries, Ltd., solid content concentration: 40% by mass). .

Example 24
Polyester for protecting a polarizer in the same manner as in Example 1 except that the particle B of the easy-adhesion layer P2 was changed to a crosslinked polystyrene particle having an average particle size of 700 nm (Glossdale 207-S manufactured by Mitsui Chemicals, solid content concentration 53 mass%). A film was obtained.

Example 25
The particles A of the easy-adhesion layer P2 are ZrO ₂ having a refractive index of 2.4 (ZR-40BL manufactured by Nissan Chemical Industries, solid content concentration 40% by mass), and the particles B are silica particles having an average particle size of 230 nm (Quatron PL manufactured by Fuso Chemical Industries). −20, a polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the solid content concentration was changed to 24% by mass.

Example 26
The particles A of the easy-adhesion layer P2 are ZrO ₂ having a refractive index of 2.4 (ZR-40BL manufactured by Nissan Chemical Industries, solid concentration 40% by mass), and the particles B are acrylic particles having an average particle size of 300 nm (gants pearl PM manufactured by Gantz Kasei). A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that it was changed to -030 and a solid content concentration of 41% by mass.

Example 27
The particles A of the easy adhesion layer P2 are ZrO ₂ having a refractive index of 2.4 (ZR-40BL manufactured by Nissan Chemical Industries, solid content concentration 40% by mass), and the particles B are silica particles having an average particle diameter of 450 nm (MP4540M manufactured by Nissan Chemical Industries, Ltd.) A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the solid content concentration was changed to 40% by mass.

Example 28
A polyester film for protecting a polarizer in the same manner as in Example 1 except that the particle A of the easy-adhesion layer P2 is changed to ZrO ₂ having a refractive index of 2.4 (ZR-40BL manufactured by Nissan Chemical Industries, solid content concentration: 40% by mass). Got.

Example 29
Particles A of the easy adhesion layer P2 are ZrO ₂ having a refractive index of 2.4 (ZR-40BL manufactured by Nissan Chemical Industries, solid concentration 40% by mass), and particles B are crosslinked polystyrene particles having an average particle size of 700 nm (Glossdale manufactured by Mitsui Chemicals). A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the content was changed to 207-S and the solid content concentration was 53% by mass.

Example 30
Particles A of the easy adhesion layer P2 are TiO ₂ having a refractive index of 2.7 (TTO-W-5 manufactured by Ishihara Sangyo Co., Ltd., solid content concentration 30% by mass), and particles B are silica particles having an average particle size of 230 nm (Quartron manufactured by Fuso Chemical Industries). A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that PL-20 was changed to a solid content concentration of 24% by mass.

Example 31
Particles A of the easy adhesion layer P2 are TiO ₂ having a refractive index of 2.7 (TTO-W-5 manufactured by Ishihara Sangyo Co., Ltd., solid content concentration 30% by mass), and particles B are acrylic particles having an average particle size of 300 nm (Gantz Pearl manufactured by Gantz Kasei). A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that PM-030 was changed to a solid content concentration of 41% by mass.

Example 32
Particles A of the easy-adhesion layer P2 are TiO ₂ having a refractive index of 2.7 (TTO-W-5 manufactured by Ishihara Sangyo Co., Ltd., solid content concentration 30% by mass), and particles B are silica particles having an average particle diameter of 450 nm (MP4540M manufactured by Nissan Chemical Industries). A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the solid content concentration was changed to 40% by mass.

Example 33
Polyester for protecting a polarizer in the same manner as in Example 1 except that the particle A of the easy-adhesion layer P2 is changed to TiO ₂ having a refractive index of 2.7 (Ishihara Sangyo TTO-W-5, solid content concentration of 30% by mass). A film was obtained.

Example 34
Particles A of the easy-adhesion layer P2 are made of TiO ₂ having a refractive index of 2.7 (TTO-W-5 manufactured by Ishihara Sangyo Co., Ltd., solid content concentration of 30% by mass), and particles B are crosslinked polystyrene particles having an average particle diameter of 700 nm (Gloss made by Mitsui Chemicals). A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that Dale 207-S was changed to a solid content concentration of 53% by mass.

Example 35
A polyester film for protecting a polarizer is obtained in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion (D-1) of the easy-adhesion layer P2 is changed to a water-soluble resin (D-2) having an oxazoline group. It was.

Example 36
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion (D-1) of the easy-adhesion layer P2 was changed to a carbodiimide water-soluble resin (D-3).

Example 37
A polarizer in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion (D-1) of the easy-adhesion layer P2 was changed to a melamine resin (Bekkamin M-3 manufactured by Dainippon Ink, Ltd., solid content concentration 60% by mass). A protective polyester film was obtained.

Example 38
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-2.

Example 39
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-3.

Example 40
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-4.

Example 41
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-5.

Example 42
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-6.

Example 43
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-7.

Example 44
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-8.

Example 45
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-9.

Example 46
A polarized polarizer protecting polyester film was obtained in the same manner as in Example 1 except that the coating solution (Z-1) for the easy adhesion layer P2 was changed to the following.
Water 40.16% by mass
Isopropanol 30.00% by mass
Polyester water dispersion (Y-1) 24.27 mass%
Block polyisocyanate aqueous dispersion (D-1) 2.78% by mass
Particle A 2.59 mass%
(Ishihara Sangyo TTO-W-5, solid concentration 30% by mass)
Particle B 0.17% by mass
(Nippon Shokubai Co., Ltd. Sea Hoster KEW50, solid content concentration 15% by mass)
Silicon-based surfactant 0.03% by mass
(Solid concentration 100% by mass)

Example 47
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution (Z-1) for the easy adhesion layer P2 was changed to the following.
Water 40.16% by mass
Isopropanol 30.00% by mass
Polyester aqueous dispersion (Y-1) 24.97% by mass
Block polyisocyanate aqueous dispersion (D-1) 2.86% by mass
Particle A 1.81% by mass
(Ishihara Sangyo TTO-W-5, solid concentration 30% by mass)
Particle B 0.17% by mass
(Nippon Shokubai Co., Ltd. Sea Hoster KEW50, solid content concentration 15% by mass)
Silicon-based surfactant 0.03% by mass
(Solid concentration 100% by mass)

Example 48
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the coating solution (Z-1) for the easy adhesion layer P2 was changed to the following.
Water 40.16% by mass
Isopropanol 30.00% by mass
Polyester aqueous dispersion (Y-1) 25.91% by mass
Block polyisocyanate aqueous dispersion (D-1) 2.96 mass%
Particle A 0.77% by mass
(Ishihara Sangyo TTO-W-5, solid concentration 30% by mass)
Particle B 0.17% by mass
(Nippon Shokubai Co., Ltd. Sea Hoster KEW50, solid content concentration 15% by mass)
Silicon-based surfactant 0.03% by mass
(Solid concentration 100% by mass)

Comparative Example 7
A polyester film for protecting a polarizer was obtained in the same manner as in Example 1 except that the polyester aqueous dispersion of the easy adhesion layer P2 was changed to Y-10.

Comparative Example 8
A polyester film for protecting a polarized polarizer in the same manner as in Example 1 except that the particle A of the easy-adhesion layer P2 is changed to SiO ₂ having a refractive index of 1.46 (Snowtex ZL manufactured by Nissan Chemical Industries, solid concentration 40% by mass). Got.

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 (5)

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 polyester resin (A) contains a 5-sulfoisophthalic acid component in a dicarboxylic acid component in an amount of 1 to 15 mol%,
The crosslinking agent (C) is an isocyanate compound or a melamine compound,
The acid value of the polyester resin (A) is 20 KOHmg / g or less,
The saponification degree of the polyvinyl alcohol-based resin (B) is 60 to 85 mol%,
The easy-adhesion layer P2 contains a polyester resin (X) containing naphthalenedicarboxylic acid as an acid component and particles, and the particles are metal oxides having a refractive index of 1.7 to 3.0.
A polyester film for protecting a polarizer, 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.
0.8 ≦ (A) / (B) ≦ 5
10 ≦ ((A) + (B)) / (C) ≦ 30 The easy-adhesion layer P2 includes at least one crosslinking agent selected from the group consisting of a urea crosslinking agent, an epoxy crosslinking agent, a melamine crosslinking agent, an isocyanate crosslinking agent, an oxazoline crosslinking agent, and a carbodiimide crosslinking agent. The polyester film for protecting a polarizer according to claim 1, further comprising: One or more functional layers 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 are provided on the easily adhesive layer P2 of the polyester film for protecting the polarizer. A polyester film for protecting a polarizer according to claim 1 or 2 . 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 1-3 . A liquid crystal display device comprising at least one polarizing plate according to claim 4 .