JP2001147320A - Protective film for polarizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizer protective film having superior antistatic property, wear resistance and transmittance for rays, which will not influence the extinction state of the polarizer in a cross-Nicol state. SOLUTION: The polarizer protective film has a coating layer having a surface resistance of 1×1012 Ω or lower formed on one surface of a polyester film having 0 to 0.005 difference for the refractive index.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective film for a polarizer, which is used by being adhered to the surface of a polarizer. The present invention relates to a protective film used for producing a polarizing plate.

[0002]

2. Description of the Related Art Generally, a polarizing plate used for a liquid crystal display panel or the like has a three-layer structure in which protective films are laminated on both surfaces of a polarizer. As the polarizer, one obtained by adsorbing iodine and / or a dichroic dye on uniaxially oriented polyvinyl alcohol is generally used. As a protective film of the polarizer, a cellulose triacetate (TAC) film is flat. It is generally used because it has excellent properties such as light transmittance and non-orientation.

[0003] As a method for producing a cellulose triacetate (TAC) film, a dope is cast on a band or a drum, peeled off, and then dried.
Solution membrane methods are commonly used. However, in this method, the film forming speed is low, and in US Pat. No. 2,607,704 and US Pat.
To increase the concentration of the dope, select a solvent, and accelerate the gelation of the dope on the band or drum in order to strip the dope from the band or drum as quickly as possible, and to dry at high temperature from both sides of the stripped dope film. Has been proposed.

[0004] However, in these methods, the viscosity of the dope is increased and the fluidity is deteriorated. When a high-concentration dope is extruded from a casting die at a high speed, the surface state of the film may be so-called sharkskin (shark skin), and the flatness may be extremely deteriorated due to a melt fracture phenomenon.

Japanese Patent Application Laid-Open No. 56-162617 discloses a method for eliminating shark skin caused by the melt fracture phenomenon.
In the official gazette, co-cast a low concentration dope on both sides of the dope,
A method of casting while enclosing a high concentration dope has been proposed. However, although the co-casting method is preferable for preventing the melt fracture phenomenon, it requires a plurality of dope adjusting steps, dope transporting steps, and the like, which is troublesome in terms of equipment.

Further, as means for solving this problem,
In Japanese Patent Application Laid-Open No. 7-32391, by controlling the doping temperature, the die temperature, and the die lip temperature, and setting the boiling point of the dope at normal pressure to a certain range,
A method for making a cellulose triacetate (TAC) film is described.

On the other hand, the polyester film has flatness,
Although excellent in light transmittance, mechanical properties, thermal properties, etc.,
Especially in biaxially oriented polyester film,
Because it has birefringence and its main orientation axis does not exist in a certain direction in the film plane, as a protective film of the polarizer,
At present it is rarely used.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polarizer that does not affect the extinction state in a crossed Nicol state and has an antistatic property. An object of the present invention is to provide a polarizer protective film having excellent wear resistance and light transmittance.

[0009]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be easily solved by using a specific film, and have completed the present invention.

That is, the gist of the present invention is that a polyester film having an in-plane refractive index difference of 0 to 0.005 has a coating layer having a surface resistance of 1 × 10 ¹² Ω or less on one surface. And a polarizer protective film.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The protective film of the present invention comprises a laminated film in which a coating layer is provided on one surface of a polyester film having an in-plane refractive index difference of 0 to 0.005, and a pressure-sensitive adhesive is provided on the surface of the polarizer. It is used by sticking through such as. In a preferred embodiment of the present invention, an adhesive layer is provided on the surface of the other polyester film provided with the coating layer, and a release film is laminated on the surface of the adhesive layer.

When the refractive index difference in the plane of the film exceeds 0.005, when the polarizing plate is arranged in a crossed Nicols state, the quenching state is hindered, and light interference color is undesirably generated.

In the present invention, a polyester film is a film obtained by stretching and orienting a sheet melt-extruded from an extrusion die according to a so-called extrusion method.

The polyester constituting the film of the present invention refers to a polyester obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid, 2,6-naphthalenedicarboxylic acid, and the like. As the aliphatic glycol,
Ethylene glycol, diethylene glycol, 1,4-
Cyclohexane dimethanol and the like. A typical polyester is polyethylene terephthalate (P
ET), polyethylene-2,6-naphthalenedicarboxylate (PEN) and the like.

The above polyester may be a copolymer containing a third component. Examples of the dicarboxylic acid component of the copolymerized polyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (for example, P-oxybenzoic acid and the like). As a glycol component,
Examples include ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, and the like. Two or more of these dicarboxylic acid components and glycol components may be used in combination.

In the present invention, it is preferable to incorporate particles into the film under conditions that do not impair the transparency, in consideration of the handling properties. As the particles, for example, silicon dioxide,
Examples thereof include calcium carbonate, aluminum oxide, titanium dioxide, kaolin, talc, zeolite, lithium fluoride, barium sulfate, carbon black, and heat-resistant polymer fine powder as described in JP-B-59-5216. These particles may be used in combination of two or more kinds. The average particle size of the particles is generally 0.02 to 2 μm, preferably 0.05 to 1.5 μm, more preferably 0.05 to 1.5 μm.
１1 μm. The content of the particles is usually 0.01 to 2% by weight, preferably 0.02 to 1% by weight.

As a method for incorporating particles into the film, a known method can be adopted. For example, particles can be added at any stage of the polyester production process. In particular, at the stage of esterification or the stage after the end of the transesterification reaction and before the start of the polycondensation reaction, it is preferable to add as a slurry dispersed in ethylene glycol or the like to advance the polycondensation reaction. Also, using a kneading extruder with a vent,
A method of blending a slurry in which particles are dispersed in ethylene glycol or water with a polyester raw material, a method of blending dried particles with a polyester raw material using a kneading extruder, and the like can also be adopted.

The production of the film is performed by a method in which a sheet melt-extruded from an extrusion die according to an extrusion method is stretched and oriented in biaxial directions of a longitudinal direction and a transverse direction.

In the extrusion method, polyester is melt-extruded from an extrusion die and cooled and solidified by a cooling roll to obtain an unstretched sheet. In this case, in order to improve the flatness of the sheet, it is necessary to increase the adhesion between the sheet and the rotary cooling drum, and the electrostatic application adhesion method or the liquid application adhesion method is preferably employed.

The method for stretching and orienting the film in the biaxial direction is not particularly limited, but a simultaneous biaxial stretching method, a sequential biaxial stretching method and the like are employed. In order to obtain in-plane refractive index isotropy, the simultaneous biaxial stretching method is preferable.

In the simultaneous biaxial stretching method, the above unstretched sheet is usually treated at 70 to 120 ° C., preferably at 80 to 110 ° C.
The stretching ratio is 4 to 50 times, preferably 7 to 35 times, more preferably 10 to 20 times in area ratio in a method of simultaneously stretching and orienting in the machine direction and the width direction while controlling the temperature. And then,
A heat treatment is performed at a temperature of 250 ° C. under tension or relaxation within 30% to obtain a stretched oriented film.

In the sequential biaxial stretching method, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C, preferably 80 to 110 ° C, and the stretching ratio is usually 2.5 to 7
Times, preferably 3.0 to 6 times. Next, stretching is performed in a direction orthogonal to the stretching direction of the first stage. The stretching temperature is usually 70 to 120 ° C, preferably 80 to 115 ° C,
The stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times.
It is twice. Subsequently, a heat treatment is performed at a temperature of 170 to 250 ° C. under tension or relaxation within 30% to obtain a stretched oriented film.

In the sequential biaxial stretching, a method in which unidirectional stretching is performed in two or more stages can be adopted. In that case, it is preferable that the stretching is performed so that the stretching ratios in the two directions finally fall within the above ranges. If necessary, the film may be stretched in the vertical and / or horizontal directions again before or after the heat treatment.

The thickness of the film of the present invention is not particularly limited, but is usually 5 to 150 μm, preferably 1 to 150 μm.
It is 0 to 100 μm, and more preferably 25 to 75 μm. When the thickness of the film is less than 5 μm, the surface protection of the polarizer may be reduced, and the handleability in the coating layer forming step and the adhesive layer forming step tends to be deteriorated.
Further, when the thickness of the film exceeds 150 μm, a decrease in flexibility and a decrease in the total light transmittance hinder a handling work as a protective film and a case where an inspection accompanied by optical evaluation is performed. There are cases.

The material constituting the coating layer of the film of the present invention includes, for example, mixtures and / or compounds of various crosslinkable resins and antistatic substances.

Specific examples of the crosslinkable resin include acrylic resins, urethane resins, melamine resins, epoxy resins, organic silicate resins, and copolymer resins of silicon-containing compounds and fluorine-containing compounds. No.

Examples of the antistatic substance include, but are not limited to, various cationic antistatic substances having a cationic group such as a quaternary ammonium salt, a pyridinium salt, and a tertiary amino group. Agent, anionic antistatic agent having an anionic group such as sulfonic acid salt group, sulfate ester salt, phosphate ester salt, phosphonate salt, etc., amphoteric antistatic agent such as amino acid type, amino sulfate type, amino alcohol type, glycerin And various surfactant-type antistatic agents such as nonionic antistatic agents such as polyethylene glycols and the like, and high molecular weight antistatic agents obtained by increasing the molecular weight of the above antistatic agents.

In the present invention, an active energy ray-curable resin is suitably used for the coating layer from the viewpoint of productivity and the like. Examples of the active energy ray-curable resin include an acrylic resin, an unsaturated polyester resin, an addition polymerization resin, a thiol / acryl hybrid resin, a cationic polymerization resin, and a hybrid resin of cationic polymerization and radical polymerization. Among these, acrylic resins are preferred in terms of curability, scratch resistance, surface hardness, flexibility, durability, and the like.

The acrylic resin contains an acrylic oligomer as an active energy ray polymerization component and a reactive diluent. And, if necessary, a photopolymerization initiator, a photopolymerization initiation auxiliary agent, a modifier and the like are contained.

A typical example of the acrylic oligomer is an oligomer having a reactive acryloyl group or methacryloyl group bonded to an acrylic resin skeleton. Other acrylic oligomers include polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, polyether (meth) acrylate, silicone (meth) acrylate, polybutadiene (meth) acrylate, and the like. Further, an oligomer in which melamine, isocyanuric acid, cyclic phosphazene, or the like is bonded to an acryloyl group or a methacryloyl group that is a rigid skeleton is exemplified.

The reactive diluent functions as a solvent in the coating process as a medium for the coating agent, and itself has a group that reacts with a polyfunctional or monofunctional acrylic oligomer. It becomes a polymerization component. Specific examples of the reactive diluent include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, and dipentaerythritol penta (meth) ) Acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene glycol (meth) acrylate, propylene glycol di (meth) acrylate, (meth) acryloyloxypropyltriethoxysilane, (meth) acryloyl Oxypropyltrimethoxysilane and the like can be mentioned.

As the photopolymerization initiator, for example, 2,2-
Ethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, dibenzoyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, p-chlorobenzophenone, p-methoxybenzophenone, Michler's ketone, acetophenone, 2-chlorothioxanthone, anthraquinone, phenyl disulfide, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone and the like.

Examples of the photopolymerization initiation aid include tertiary amines such as triethylamine, triethanolamine and 2-dimethylaminoethanol, alkylphosphines such as triphenylphosphine, and thioethers such as β-thiodiglycol.

Examples of the modifier include an antistatic agent, a coating improver, an antifoaming agent, a thickener, an inorganic particle, an organic particle, a lubricant, an organic polymer, a dye, a pigment and a stabilizer. Can be These are used within a range that does not inhibit the reaction by the active energy ray, and can improve the properties of the active energy ray-curable resin layer according to the application. An organic solvent can be added to the composition of the active energy ray-curable resin layer for the purpose of improving workability during coating and controlling the coating thickness.

In the present invention, the coating layer preferably contains an ultraviolet absorber, and examples of the ultraviolet absorber include an organic ultraviolet absorber and an inorganic ultraviolet absorber.

Examples of the organic ultraviolet absorber include salicylic acids, for example, phenylsalicylate, pt-butylphenylsalicylate, p-octylphenylsalicylate, and benzophenones, for example, 2-hydroxy-4.
-Benzyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone Benzotriazoles such as 2,2-2′-dihydroxy-4,4′-dimethoxybenzophenone,
-(2'-hydroxy-5'-t-octylphenyl)
-Benzotriazole, 2- (2'-hydroxy-5 '
-Methylphenyl) benzotriazole, 2- (2'-
Hydroxy-3'5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-
Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'5'-di-
Examples thereof include natural products such as t-butylphenyl) -5-chlorobenzotriazole, such as oryzanol, shea butter, and baicalin; and biological systems such as keratinocytes, melanin, and urocanic acid. These organic UV absorbers can be used alone or in combination of two or more. A hindered amine compound can be used in combination with these organic ultraviolet absorbers as an ultraviolet stabilizer.

Examples of the inorganic ultraviolet absorber include titanium oxide, zinc oxide, indium oxide, tin oxide, talc, kaolin, calcium carbonate, titanium oxide-based composite oxide, zinc oxide-based composite oxide, and ITO (tin-doped indium oxide). ), ATO (antimony-doped tin oxide) and the like. Examples of the titanium oxide-based composite oxide include silica, alumina-doped titanium oxide and the like,
Examples of the zinc oxide-based composite oxide include aluminum-doped zinc oxide. These inorganic ultraviolet absorbers can be used alone or in combination of two or more. Further, an organic ultraviolet absorber and an inorganic ultraviolet absorber may be used in combination.

In the present invention, as a coating method, a reverse roll coating method, a gravure roll coating method, a rod coating method, an air knife coating method, or the like can be adopted.

The applied curable resin composition is cured by, for example, active energy rays or heat. As the active energy rays, ultraviolet rays, visible rays, electron beams, X-rays,
α rays, β rays, γ rays and the like are used. As a heat source, an infrared heater, a heat oven, or the like is used. Irradiation with active energy rays is usually performed from the side of the coating layer, but may be performed from the side opposite to the coating layer in order to increase the adhesion to the film. If necessary, a reflector that can reflect active energy rays may be used. The film cured by the active energy rays has particularly good abrasion resistance.

In the present invention, the surface resistance of the coating layer is 1 ×
10¹²Ω or less, preferably 1 × 10 ¹¹Ω or less, even better
Preferably 1 × 10^TenΩ or less. The surface resistance of the coating layer
1 × 10¹²If it exceeds Ω, dust and dirt adhere to the surface
In some cases, this is not preferable.

The coating amount of the coating layer is particularly limited.
Not usually, but 0.1 to 10 g / m ^Two, Preferably 0.
2 to 5 g / m^TwoRange. 0.1 g / m coating amount^Two
If it is less than 10, the antistatic property tends to decrease, and
g / m^TwoWhen it exceeds, the curing shrinkage of the coating layer becomes large.
And the film may curl toward the coating layer.

In the present invention, the total light transmittance of the protective film is preferably 85% or more, more preferably 90% or more. When the total light transmittance is less than 85%, for example, when used as a constituent member of a liquid crystal display panel or the like, hue, luminance, brightness, contrast, and the like may be reduced.

[0044]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the examples and comparative examples, “parts” means “parts by weight”. The measuring methods and evaluation criteria used in the present invention are as follows. (1) In-plane refractive index difference: 10 mm in width and 50 in length while shifting the angle by 10 degrees
mm sample was taken from the film, and the refractive index of each sample in the direction of the sampling angle was measured with an Abago refractometer manufactured by Atago Optical Co., Ltd. The measurement of the refractive index was performed at 23 ° C. using a sodium D line. The difference between the maximum value and the minimum value of the refractive index obtained in the measurement (the maximum value of the refractive index−the minimum value of the refractive index) was calculated, and the difference was taken as the refractive index difference. (2) Surface resistance of coating layer (Ω) A sample was placed in an atmosphere of 23 ° C./50% RH, and 500
A voltage of V was applied, and the surface resistance (Ω) was measured one minute later (the voltage application time was one minute). The type of electrode used here is a concentric electrode having an outer diameter of the main electrode of 16 mm and an inner diameter of the counter electrode of 40 mm. (3) Total light transmittance of the laminated film According to JIS-K7105, the total light transmittance was measured by an integrating sphere turbidimeter (“NDH-300A” manufactured by Nippon Denshoku Industries Co., Ltd.). (4) Quenching state Two polarizing plates on which the sample films were attached were overlapped so that the polarizer was in a crossed Nicol state, and white light was irradiated from below, and the quenching state when viewed from above was evaluated. (5) Abrasion resistance Using "RUBING TESTER" manufactured by Ohira Rika Kogyo Co., Ltd., a long-fiber cellulose nonwoven fabric was wound around a metal flat plate indenter of 65 mm x 50 mm and rubbed 100 times. Thereafter, the surface was observed, and the case where the coating layer hardly changed was evaluated as good, and the case where the coated layer was dropped was evaluated as poor. (6) Antistatic properties: Ash of cigarettes is dropped on the surface of the coating layer of the laminated film.
The state of adhesion of the ash during rotation (360 degree rotation) was observed, and the quality of the antistatic property was evaluated.

Production Example 1 (Polyester A) 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate were placed in a reactor, heated and heated, and methanol was distilled off. The temperature was raised to 230 ° C. over 4 hours from the start of the reaction, and the transesterification was substantially completed. Next, an ethylene glycol slurry containing 0.1 part of silica particles having an average particle size of 1.54 μm was added to the reaction system, and ethyl acid phosphate was added to the slurry.
After adding 04 parts and 0.01 parts of germanium oxide, 1
At 00 minutes, the temperature was 280 ° C. and the pressure was 15 mmHg. Thereafter, the pressure was gradually reduced to finally 0.3 mmHg. After 4 hours, the inside of the system was returned to normal pressure to obtain polyester A. The content of the silica particles of the polyester A was 0.1% by weight.

Production Example 2 (Polyester Film A1) Polyester A was dried at 180 ° C. for 4 hours in an inert gas atmosphere, melt-extruded at 290 ° C. by a melt extruder, and the surface temperature was adjusted by using an electrostatic application adhesion method. It was cooled and solidified on a cooling roll set at 40 ° C. to obtain an unstretched sheet. The obtained sheet was treated with T.I. M. Simultaneous biaxial stretching was performed using a long stretching machine manufactured by Long Corporation at 95 ° C. so that the area ratio became 16 times. After that, it is heat-set at 230 ° C.
A polyester film A1 was obtained. The difference in the refractive index of the obtained film was 0.001.

Production Example 3 (Polyester Film A2) A polyester film A2 was obtained in the same manner as in Production Example 2 except that simultaneous biaxial stretching was performed so that the stretching ratio was 12 times the area magnification. The difference in the refractive index of the obtained film was 0.001.

Production Example 4 (Polyester film A3) A polyester film A3 was obtained in the same manner as in Production Example 2, except that simultaneous biaxial stretching was performed so that the stretching ratio was 20 times the area magnification. The difference in the refractive index of the obtained film was 0.001.

Production Example 5 (Polyester film A4) Polyester A was dried at 180 ° C. for 4 hours in an inert gas atmosphere, melt-extruded at 290 ° C. by a melt extruder, and the surface temperature was adjusted by using an electrostatic contact method. It was cooled and solidified on a cooling roll set at 40 ° C. to obtain an unstretched sheet. After stretching the obtained sheet 3.5 times in the longitudinal direction at 85 ° C.,
The film was stretched 3.7 times in the transverse direction at 0 ° C., and further heat-set at 230 ° C. to obtain a 38 μm-thick polyester film A4. The refractive index difference of the film was 0.025.

Example 1 30 parts of dipentaerythritol hexaacrylate, 4 parts
In an active energy ray-curable resin composition comprising 40 parts of a functional urethane acrylate, 27 parts of a bisphenol A type epoxy acrylate and 3 parts of 1-hydroxycyclohexyl phenyl ketone, 0.6 part of ITO particles having a particle size of 0.02 μm and ATO particles are prepared. 0.4 part of a methacrylimide copolymer containing a quaternary ammonium salt as an antistatic agent was blended on one surface of the polyester film A1 so that the thickness after curing was 1 g / m ^2. It was applied and irradiated for 15 seconds at an irradiation distance of 100 mm using a high-pressure mercury lamp having an energy of 120 W / cm to form a cured film. Then, an acrylic pressure-sensitive adhesive was applied on the surface opposite to the surface on which the cured film was applied, and a polarizer and a sample film were adhered to obtain a laminate.

Example 2 A laminate was obtained in the same manner as in Example 1 except that a cured film was formed so that the thickness after curing became 0.5 g / m ² .

Example 3 A laminate was obtained in the same manner as in Example 1 except that a cured film was formed so that the thickness after curing became 0.2 g / m ² .

Example 4 A laminate was obtained in the same manner as in Example 1, except that the polyester film A1 was changed to the polyester film A2.

Example 5 A laminate was obtained in the same manner as in Example 1, except that the polyester film A1 was changed to the polyester film A3.

Comparative Example 1 A laminate was obtained in the same manner as in Example 1, except that the polyester film A1 was changed to the polyester film A4.

Comparative Example 2 In Example 1, except that no cured film was formed,
A laminate was obtained in the same manner as in Example 1. Comparative Example 3 Example 1 was repeated except that 5 parts of the quaternary ammonium salt-containing methacrylimide copolymer were not blended.
To obtain a laminate.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

According to the present invention, it is possible to provide a protective film having excellent antistatic properties, abrasion resistance and light transmittance without affecting the extinction state of the polarizer in the crossed Nicols state. The industrial value of the present invention is high.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H049 BB13 BB20 BB23 BB24 BB67 BC01 BC03 2H091 FA08X FA08Z FA50X FA50Z FB02 FB12 FC09 FC22 FD06 FD15 LA02 LA03 LA07 4F100 AA33H AK01B AK25 AK25A51A53AK51J53 CA22 CB05 CC03B DE01H GB41 JB13B JB14 JG03 JG04B JK09 JN01 JN08 JN18A YY00 YY00A YY00B

Claims (3)

[Claims] 2. The method according to claim 1, wherein the difference in refractive index within the film plane is from 0 to 0.00.
5. A polarizer protective film comprising a polyester film having a coating layer having a surface resistance of 1 × 10 ¹² Ω or less on one surface of the polyester film. 2. The polarizer protective film according to claim 1, wherein the coating layer is mainly composed of a cured resin containing an ultraviolet absorber. 3. The polarizer protective film according to claim 1, wherein the total light transmittance is 85% or more.