JPH1170629A - Surface protective film for liquid crystal display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the surface protective film for liquid crystal display panel having characteristics excellent in handling properties, facilitating the inspection of a liquid crystal display panel accompanied by optical evaluation and excellent in the prevention of the adhesion of waste refuse to the liquid crystal display panel. SOLUTION: The surface protective film laminated to the surface of the polarizing plate or phase difference plate of a liquid crystal display panel to be used is composed of a laminated film wherein an abrasion-resistant layer is provided on one surface of a biaxially oriented polyester film with a thickness of 5-50 μm and a self-adhesive layer is provided on the other surface thereof and the above mentioned biaxially oriented polyester film has a retardation value of 30-10,000 nm and the abrasion-resistant layer has surface resistivity of below 1×10<10> Ω and the laminated film has total light transmissivity of 80% or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface protection film for a liquid crystal display panel, and more particularly, to a method for attaching the same to a polarizing plate or a retardation plate of a liquid crystal display panel.
The present invention relates to a liquid crystal display panel surface protective film used for protecting the surface of a polarizing plate or a retardation plate.

[0002]

2. Description of the Related Art Generally, a liquid crystal display panel is manufactured by laminating a polarizing plate or a retardation plate on both sides of a liquid crystal cell in which liquid crystal is sealed between two substrates. A protective film is applied to the surface of the polarizing plate or retardation plate in order to prevent abrasion and dust adhesion on the surface of the polarizing plate or retardation plate in the distribution process and in the assembly process of various display devices such as computers, word processors, and televisions. Affixed. Such a protective film is peeled and removed as an unnecessary substance after having served the role of protecting the polarizing plate or the retardation plate. Usually, peeling and removal of the protective film is performed by a method of pressing an adhesive tape against the protective film and lifting the adhesive tape.

Conventionally, polyethylene films, ethylene-vinyl acetate copolymer films and the like have been used as the above protective films. However, these protective films may hinder inspections involving optical evaluations such as display capability, hue, contrast, and contamination of liquid crystal display panels. There is a disadvantage that must be attached.

Japanese Patent Application Laid-Open No. Hei 4-30120 proposes a protective film in which an optically isotropic adhesive resin layer is laminated on an optically isotropic substrate film, as a protective film which does not need to be peeled off during an inspection involving optical evaluation. Have been. However, this protective film is formed by a casting method as a base film, and therefore, a film that is almost non-oriented and almost amorphous is used, so that the chemical resistance,
It is not sufficient in terms of scratch resistance and the like.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and its object is to provide an excellent handleability.
Inspection of liquid crystal display panel with optical evaluation is easy, and it has characteristics such as excellent prevention of dust adhesion to liquid crystal display panel,
An object of the present invention is to provide a liquid crystal display panel surface protective film.

[0006]

That is, the gist of the present invention is to provide a liquid crystal display panel surface protection film which is used by being adhered to the surface of a polarizing plate or a phase difference plate of a liquid crystal display plate, and has a thickness. A biaxially oriented polyester film of 5 to 50 μm is composed of a laminated film in which an abrasion-resistant layer is provided on one surface and an adhesive layer is provided on the other surface, and the biaxially oriented polyester film has a retardation value of 30. ~ 1
Wherein the abrasion-resistant layer has a surface resistivity of less than 1 × 10 ¹⁰ Ω, and the laminated film has a total light transmittance of 80% or more. Exist in protective film.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The liquid crystal display panel surface protective film of the present invention is used by being adhered to the surface of a polarizing plate or a retardation plate of a liquid crystal display plate, and provided with a wear-resistant layer on one surface of a biaxially oriented polyester film and the other. From a laminated film provided with an adhesive layer on the surface of the film. Then, in a preferred embodiment of the present invention, a release film is laminated on the surface of the adhesive layer. Such a liquid crystal display panel surface protection film of the present invention is generally
It is manufactured through a wear-resistant layer forming step, an adhesive layer forming step, and a release film laminating step sequentially.

In the present invention, a biaxially oriented polyester film (hereinafter abbreviated as a film) refers to a sheet melt-extruded from an extrusion die according to a so-called extrusion method and stretched in a biaxial direction in a machine direction and a transverse direction. Film.

The polyester constituting the above film refers to a polyester obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. No. 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. As the dicarboxylic acid component of such a copolymerized polyester, isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid,
Adipic acid, sebacic acid, oxycarboxylic acid (for example,
P-oxybenzoic acid, etc.), and as a glycol component, ethylene glycol, diethylene glycol,
Examples thereof include propylene glycol, butanediol, 1,4-cyclohexanedimethanol, and neopentyl glycol. These dicarboxylic acid components and glyco-
Two or more components may be used in combination.

In the present invention, in consideration of the handling properties, it is preferable that particles are contained in the film under conditions that do not impair transparency. Examples of the particles include silicon dioxide, calcium carbonate, aluminum oxide, titanium dioxide, kaolin, talc, zeolite, lithium fluoride, barium sulfate, carbon black, and JP-B-59-5.
No. 216, heat-resistant polymer fine powder, and the like. These particles may be used in combination of two or more kinds. The average particle size of the particles is usually 0.02 to 2 μm.
m, preferably 0.05 to 1.5 μm, more preferably 0.05 to 1 μm. The content of particles is usually 0.0
The content is 1 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 employed. For example, particles can be added at any stage of the polyester production process. In particular, at the stage of esterification or at 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. Further, 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, and using a kneading extruder, drying the dried particles and the polyester raw material. A blending method may be employed.

The production of the film is carried out by a method in which a sheet melt-extruded from an extrusion die according to an extrusion method is stretched and oriented biaxially in a machine direction and a transverse direction.

In the extrusion method, a polyester is melt-extruded from an extrusion die and cooled and solidified by a cooling roll to obtain an undrawn 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 electrostatic application contact method is generally such that a linear electrode is stretched on the upper surface of a sheet in a direction perpendicular to the flow of the sheet.
By applying a DC voltage of about 5 to 10 kV to the electrodes, a static charge is applied to the sheet to improve the adhesion between the sheet and the drum. The liquid application adhesion method refers to the whole or a part of the surface of the rotary cooling drum (for example,
This is a method of improving the adhesion between the drum and the sheet by uniformly applying the liquid only to the portions in contact with both ends of the drum. In the present invention, both may be used as needed.

In the biaxial stretching, the unstretched sheet is first stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C,
Preferably it is 80-110 degreeC, and a draw ratio is 2.5-7 times normally, Preferably it is 3.0-6 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 11 ° C.
The stretching ratio is usually 3.0 to 7 times, and preferably 3.5 to 6 times. And, continuously, 170-2
Heat treatment is performed at a temperature of 50 ° C. under tension or relaxation within 30% to obtain a biaxially oriented film.

In the above stretching, the stretching in one direction is performed by 2
It is also possible to adopt a method of performing the above steps. In that case, it is preferable that the stretching is performed so that the stretching ratio in the two directions finally falls within the above range. It is also possible to simultaneously biaxially stretch the unstretched sheet so that the area magnification becomes 10 to 40 times. Further, if necessary, the film may be stretched in the longitudinal and / or transverse directions again before or after the heat treatment.

In the present invention, the film has a thickness of 5 to 5.
50 μm, retardation (Retardatio)
n) The value must be between 30 and 10,000 nm.
When the thickness of the film is less than 5 μm, the surface protection of the liquid crystal display panel is deteriorated, and the handleability in the abrasion-resistant layer forming step and the adhesive layer forming step is deteriorated. In the case of exceeding, the increase of the retardation value and the decrease of the total light transmittance hinder the inspection when the optical performance such as the display capability, hue, contrast, and foreign matter inclusion of the liquid crystal display panel is evaluated. On the other hand, when the retardation value is less than 30 nm, the chemical resistance of the film deteriorates. When the retardation value exceeds 10,000 nm, the distance between the polarizing plate and the protective film depends on the angle (θ3) of the orientation axis of the film. It becomes a cross Nicol state and becomes an extinction state. The thickness of the film is preferably 10 μm to 40 μm
And the retardation value is preferably 50 to 50.
00 nm, more preferably 100 to 2000 nm.

In the present invention, examples of the constituent material of the wear-resistant layer include various cross-linkable resins, metal oxides, and hard carbon materials. Usually, cross-linkable resins are preferably used. . Specific examples of the crosslinkable resin include an acrylic resin, a urethane resin, a melamine resin, an epoxy resin, an organic silicate resin, and a copolymer resin of a silicon-containing compound and a fluorine-containing compound.

In the present invention, an active energy ray-curable resin is preferably used from the viewpoint of productivity and the like. As the active energy ray-curable resin, unsaturated polyester resin, acrylic resin, addition polymerization resin, thiol
Acrylic hybrid resin, cationic polymerization resin,
Hybrid resins of cationic polymerization and radical polymerization are exemplified. Among these, acrylic resins are preferred in terms of curability, scratch resistance, surface hardness, flexibility, durability, and the like.

The above 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 having 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. Component. Specific examples of such a reactive diluent include pentaerythritol tri (meth)
Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropanetri (Meth) acrylate, ethylene glycol (meth) acrylate, propylene glycol di (meth) acrylate, (meth)
Acryloyloxypropyltriethoxysilane, (meth) acryloyloxypropyltrimethoxysilane and the like can be mentioned.

Examples of the photopolymerization initiator include, 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.

As the modifier, a coating improver, an antifoaming agent,
Examples include a thickener, inorganic particles, organic particles, a lubricant, an organic polymer, a dye, a pigment, and a stabilizer. They are,
It is used in a range that does not inhibit the reaction by the active energy ray, and the properties of the active energy ray-curable resin layer can be improved according to the application. An organic solvent can be added to the composition of the active energy ray-curable resin layer in order to improve workability during coating and control the coating thickness.

In the present invention, the following method can be employed to impart an antistatic property to the surface protective film of the liquid crystal display panel. That is, (1) a method of depositing a conductive material such as chromium vapor deposition on a film, (2) a method of kneading an antistatic agent into a film, (3) a method of providing an antistatic agent-containing coating layer on a film, (4) A method of including an antistatic agent in the wear-resistant layer can be employed. Among these, the method (3) or (4) is recommended.

Examples of the antistatic agent include various cationic antistatic agents having a cationic group such as a quaternary ammonium salt, a pyridinium salt, and a tertiary to tertiary amino group.
Anionic antistatic agents having anionic groups such as sulfonic acid groups, sulfate ester groups, phosphate ester groups, phosphonate groups, amino acid-based, aminosulfate-based amphoteric antistatic agents, amino alcohol-based, glycerin-based, Examples include various surfactant-type antistatic agents such as nonionic antistatic agents such as polyethylene glycols, and high-molecular-weight antistatic agents obtained by increasing the molecular weight of the above-described antistatic agents.

It is preferable that the abrasion resistant layer contains a silicone compound in order to impart appropriate releasability. Examples of the type of the silicone compound include a silicone oil, a silicone resin, and a silicone rubber. Compounds based on silicone are preferred. Such compounds include, for example, linear dimethylpolysiloxane gum, organically modified polysiloxane, and the like.

The content of the silicone compound in the wear-resistant layer is usually 0.5 to 60% by weight, preferably 0.5 to 5% by weight.
0% by weight, more preferably 1 to 40% by weight. When the content of the silicone compound exceeds 60% by weight,
When the protective film is removed due to a decrease in the adhesive strength with the adhesive tape, it becomes difficult to adhere to the adhesive tape. When the content is less than 0.5% by weight, those cut to the target polarization angle or phase angle are stacked. When being handled by being handled, the cut edge adhesive may adhere to the surface of the protective film of another polarizing plate or retardation plate.

The formation of the abrasion-resistant layer is carried out by applying a curable resin composition to one surface of the film and curing it. 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 employed. Curing of the applied curable resin composition is performed by, for example, active energy rays or heat. Ultraviolet rays, visible rays, electron beams, X-rays, α-rays, β-rays, γ-rays and the like are used as the active energy rays. 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.

The thickness of the wear-resistant layer is usually 0.5 to 10 μm.
m, preferably in the range of 1 to 5 μm. 0.5 thickness
If it is less than μm, the abrasion resistance is reduced, and if it is more than 10 μm, the curing shrinkage of the abrasion-resistant layer increases, and the film may curl toward the abrasion-resistant layer.

In the present invention, the wear-resistant layer must have a surface resistivity of less than 1 × 10 ¹⁰ Ω. If the surface resistivity of the abrasion-resistant layer exceeds the above value, static electricity is likely to be generated, and adhesion of dust increases. The surface resistivity of the wearable layer is preferably less than 5 × 10 ⁹ Ω, more preferably 1 × 10 ⁹ Ω.
It is less than 10 ⁹ Ω.

In the present invention, the coefficient of friction of the wear-resistant layer with respect to the polyester film is preferably 0.3 or less. The reason is as follows. The films that have undergone the abrasion resistant layer forming step are stored in a stacked state before being carried into the adhesive layer forming step. When the friction coefficient of the wear-resistant layer exceeds 0.3, the above-mentioned storage may cause blocking (sticking) between the wear-resistant layer and the film that are in contact with each other at the time of storage, thereby deteriorating the handleability. . Therefore, in the present invention, in order to avoid such a problem, it is recommended to adjust the friction coefficient of the abrasion-resistant layer to the polyester film. The coefficient of friction of the wear-resistant layer with respect to the polyester film is preferably 0.25 or less.

In the present invention, the surface roughness (Ra) of the wear-resistant layer is preferably not more than 0.03 μm. That is, the surface roughness (Ra) of the wear-resistant layer is 0.03 μm
If exceeds, with the decrease in transparency, even if the thickness and retardation value of the film are in the above range, it may cause a problem in an inspection involving optical evaluation in a state where the protective film is attached. . Therefore, in the present invention, it is recommended to adjust the surface roughness (Ra) of the wear-resistant layer in order to perform the above-mentioned inspection with the protective film attached without any problem. Surface roughness of the wear-resistant layer (R
a) is preferably 0.025 μm or less.

In the present invention, it is preferable that the peeling force of the abrasion-resistant layer against the pressure-sensitive adhesive described below is 500 gf / 50 mm or less. The reason is as follows. The liquid crystal display panel surface protection film of the present invention is stored in a stacked state. During this storage, the adhesive layer that accidentally protrudes from between the polyester film and the release film may come into contact with the abrasion-resistant layer of another protective film in the step of cutting to a predetermined size. The contact of the pressure-sensitive adhesive layer with the wear-resistant layer causes the adhesion of the pressure-sensitive adhesive to the wear-resistant layer when the adhesive force of the pressure-sensitive adhesive increases. Therefore, in order to avoid such a problem, in the present invention, it is recommended to adjust the peeling force of the wear-resistant layer with respect to the pressure-sensitive adhesive described later.

In the present invention, the pressure-sensitive adhesive layer comprises a known pressure-sensitive adhesive, for example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a block copolymer-based pressure-sensitive adhesive, a polyisobutylene-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive. Generally, such a pressure-sensitive adhesive is constituted as a composition such as an elastomer, a tackifier, a softener (plasticizer), a deterioration inhibitor, a filler, and a crosslinking agent.

As the elastomer, for example, natural rubber, synthetic isoprene rubber, reclaimed rubber, SBR, block copolymer, polyisobutylene, butyl rubber, polyacrylate copolymer, silicone rubber, etc. may be used according to the type of each of the above-mentioned adhesives. No.

Examples of the tackifier include rosin, hydrogenated rosin ester, terpene resin, aromatic modified terpene resin, hydrogenated terpene resin, terpene phenol resin, aliphatic petroleum resin, aromatic petroleum resin, and lipophilic resin. Group-based hydrogenated petroleum resins, coumarone-indene resins, styrene resins, alkylphenol resins, xylene resins, and the like.

Examples of the softener include paraffinic process oil, naphthenic process oil, aromatic process oil, liquid polybutene, liquid polyisobutylene, liquid polyisoprene, dioctyl phthalate, dibutyl phthalate, castor oil, and tall oil. Can be

Examples of the deterioration inhibitor include aromatic amine derivatives, phenol derivatives, and organic thioacid salts.

Examples of the filler include zinc white, titanium white, calcium carbonate, clay, pigment, carbon black and the like. When a filler is contained, it is used within a range that does not significantly affect the total light transmittance of the protective film.

As a crosslinking agent, for example, sulfur and a vulcanization aid and a vulcanization accelerator (typically zinc dibutylthiocarbamate and the like) are used for crosslinking a natural rubber-based pressure-sensitive adhesive. Polyisocyanates are used as a crosslinking agent capable of crosslinking a natural rubber and a carboxylic acid copolymerized polyisoprene as raw materials at room temperature. A polyalkylphenol resin is used as a cross-linking agent such as butyl rubber and natural rubber which has characteristics of heat resistance and non-staining. Crosslinking of adhesives made from butadiene rubber, styrene-butadiene rubber and natural rubber includes organic peroxides such as benzoyl peroxide and dicumyl peroxide, and non-staining adhesives are obtained.
Polyfunctional methacrylic esters are used as a crosslinking assistant. In addition, there is formation of a pressure-sensitive adhesive by crosslinking such as ultraviolet crosslinking and electron beam crosslinking.

The formation of the pressure-sensitive adhesive layer is performed by applying a pressure-sensitive adhesive to the other surface of the film. As a coating method, the same method as that used for forming the wear-resistant layer can be adopted. The thickness of the adhesive layer is generally in the range of 0.5 to 10 μm, preferably 1 to 5 μm.

In the present invention, when the pressure-sensitive adhesive tape is pressed against the abrasion-resistant layer and the pressure-sensitive adhesive tape is lifted, the pressure-sensitive adhesive layer is removed from the surface of the polarizing plate or the retardation plate together with the biaxially oriented polyester film. It is adjusted so that it is peeled and removed. In this case, the adhesive strength between the polarizing plate or the retardation plate and the adhesive layer is preferably in the range of 5 to 200 gf / 50 mm. And on the surface of the adhesive layer,
From the viewpoint of facilitating handling, a known release film is laminated.

The laminated film (liquid crystal display panel surface protective film) of the present invention having the above-mentioned structure has a total light transmittance (T
L) is 80%, preferably 85% or more. As a result, an inspection involving optical evaluation such as display ability, hue, contrast, and contamination of a liquid crystal display panel can be performed with the protective film adhered to the surface of the polarizing plate or retardation plate.

[0046]

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. 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) Thickness of the biaxially oriented polyester film: Mumetron “4M-100P” manufactured by Citizen Watch Co., Ltd.
The film thickness was measured using "TYPE V-2".

(2) Retardation value (Re) of biaxially oriented polyester film: Using an Abbe refractometer manufactured by Atago Optical Co., Ltd., the maximum in-plane refractive index nγ and the refractive index nβ in a direction perpendicular to the film. And the difference (n
γ-nβ) was calculated. The difference (nγ−nβ) was multiplied by the thickness of the film whose refractive index was measured to obtain a retardation value.

(3) Surface resistivity (Ω) of wear-resistant layer: “Hiresta Model HT-21” manufactured by Mitsubishi Yuka
Using “0”, the sample was placed in an atmosphere of 23 ° C./50% RH, a voltage of 500 V was applied, and the surface resistance (Ω) after charging for 1 minute (voltage application time of 1 minute) was measured. 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. The value obtained by multiplying the measured surface specific resistance (Ω) by 10 was defined as the surface resistivity (Ω).

(4) Friction coefficient of abrasion-resistant layer: Abrasion-resistant layer surface of a sample film cut to a width of 15 mm and a length of 150 mm on a smooth glass plate and a polyester film (T100-38 manufactured by Diafoil Hoechst) , A rubber plate is placed thereon, and a load is further placed thereon, and the contact pressure of the two films is set to 0.5 g / mm ² , and 20 mm / m ²
The frictional force was measured by sliding the films at a speed of in. The value at the point of sliding by 5 mm was calculated to be the coefficient of friction. The measurement was performed in an atmosphere at a temperature of 23 ° C. and a humidity of 50%.

(5) Surface roughness (Ra) of the wear-resistant layer: The center line average roughness Ra (μm) is defined as the surface roughness. Surface roughness measuring machine (“SE-3F” manufactured by Kosaka Laboratory Co., Ltd.)
And was determined as follows. That is, a reference length L (2.5 mm) from the film cross-section curve in the direction of its center line
, And the center line of the extracted part is the x-axis,
When the direction of the vertical magnification is represented by the roughness curve y = f (x) using the y-axis as the y-axis, the value given by the following equation is represented by [μm]. The center line average roughness was obtained by calculating ten cross-sectional curves from the surface of the sample film, and expressing the average value of the center line average roughness of the sampled portion obtained from these cross-sectional curves. The tip radius of the stylus was 2 μm, the load was 30 mg, and the cutoff value was 0.08 mm.

[0052]

(Equation 1)

(6) Peeling force of the abrasion-resistant layer to the adhesive: A double-sided adhesive tape (Nitto Denko Corporation “N
o. 502 ") and 450g using a rubber roller
/ Cm, and cut out to a width of 50 mm to obtain a sample for peel force measurement. After leaving for 1 hour after pressing, using an Instron type tensile tester, a tensile speed of 30 in the 180-degree direction.
0 mm / min. And the average value of the stress was taken as the peeling force of the sample. This test was repeated 10 times, and
The arithmetic average of the times was taken as the peel force. The atmosphere in which this test was performed is a standard condition of 23 ° C. and 50% RH.

(7) Total light transmittance (T) of the laminated film
L): Total light transmittance (TL) was measured with an integrating sphere turbidimeter (“NDH-300A” manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS-K7105.

(8) Handleability: The handleability of the film in the step of forming the abrasion-resistant layer and the step of forming the adhesive layer and the handleability of the laminated film at the time of sticking to the deflection plate were evaluated.

(9) Light-extinguishing state: A film containing a foreign substance for evaluating characteristics was arranged between two deflection plates in a crossed Nicols state, and the presence or absence of a light-extinguishing state when the whole was viewed from above through a sample film was observed.

(10) Evaluation of abrasion resistance: Using "RUBING TESTER" manufactured by Ohira Rika Kogyo Co., Ltd., 65 mm
A long fiber cellulose nonwoven fabric was wound around a 50 mm metal flat plate indenter, and 1 ml of ethyl acetate was impregnated to rub the surface of the abrasion-resistant layer 100 times. Thereafter, the surface was observed, and the case where the wear-resistant layer hardly changed was evaluated as good, and the case where the wear-resistant layer was dropped was evaluated as poor.

(11) Dust adhesion: Tobacco ash was dropped on the surface of the abrasion resistant layer of the laminated film, and the state of adhesion of the ash after one rotation (360 ° rotation) was observed. The presence or absence was evaluated.

(12) Blocking property: Two polyester films each having a wear-resistant layer formed thereon are stacked, the lower film is fixed, and the upper film is pushed with a finger and slid, so that the wear-resistant layer and the polyester film are combined. The presence or absence of blocking between them was investigated.

(13) Easiness of inspection: A film containing a foreign substance for property evaluation was arranged between two deflection plates in a crossed Nicols state, and the visibility of the foreign substance when the whole was viewed from above through the sample film was evaluated. .

(14) Adhesive adhesion: An acrylic adhesive was rubbed on the surface of the abrasion-resistant layer, and the presence or absence of adhesive adhesion 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 transesterification reaction was performed, and the temperature was raised to 230 ° C. over 4 hours from the start of the reaction, and the transesterification reaction was substantially completed. Then, silica particles having an average particle size of 1.54 μm were added to 0.1%.
1 part of an ethylene glycol slurry was added to the reaction system, and further, ethyl acid phosphate 0.04 was added.
Parts, 0.01 part of germanium oxide,
In a minute, the temperature reaches 280 ° C and the pressure reaches 15mmHg,
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 is 0.1
% By weight.

Production Example 2 (Polyester B) In Production Example 1, instead of ethylene glycol slurry containing 0.1 part of silica particles having an average particle diameter of 1.54 μm, 1 part of titanium oxide particles having an average particle diameter of 0.27 μm was contained. Polyester B was obtained in the same manner as in Production Example 1 except that the ethylene glycol slurry used was used. The content of the titanium oxide particles in the polyester B was 1% by weight.

Production Example 3 (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 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 25 μm-thick polyester film A1. The retardation value of the film was 700 nm.

Production Example 4 (Polyester film A2) A 38 μm-thick polyester film A2 was obtained in the same manner as in Production example 3. The retardation value of the film was 990 nm.

Production Example 5 (Polyester film A3) A 3 μm-thick polyester film A3 was obtained in the same manner as in Production Example 3. The retardation value of the film is 9
It was 0 nm.

Production Example 6 (Polyester Film A4) A 75 μm thick polyester film A4 was obtained in the same manner as in Production Example 3. The retardation value of the film was 2,200 nm.

Production Example 7 (Polyester film A5) Except for stretching in the longitudinal direction in Production Example 3, the following aqueous dispersion coating solution was applied so that the coating thickness after stretching and drying was 0.1 μm. In the same manner as in Production Example 3, a polyester film A5 was obtained. The retardation value of the obtained film was 700 nm.

The above aqueous dispersion coating solution was prepared as follows. That is, first, p-styrenesulfonic acid sodium salt (40 parts) and vinylsulfonic acid sodium salt (4
0), N, N'-dimethylaminomethacrylate (2
0 part) was dissolved in distilled water, and 2,2′-azobis (2-aminodipropane) dihydrochloride was added as a polymerization initiator while heating and stirring at 60 ° C. to carry out polymerization, thereby preparing an antistatic resin. Obtained.

Next, 30 parts of the antistatic resin was
Polyurethane resin (isocyanate component: isophorone diisocyanate, polyol component: polyester polyol composed of terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, chain extender:
50 parts of 2,2-dimethylolpropionic acid, 10 parts of acrylic resin (structural units: methyl methacrylate, N, N'-dimethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, butyl acrylate)
Five parts of the functional water-soluble epoxy compound and 5 parts of colloidal silica having an average particle size of 0.1 μm were blended to prepare a water dispersion coating solution.

Production Example 8 (Polyester film B1) A 50 μm thick polyester film was prepared in the same manner as in Production Example 3 except that Polyester A was changed to Polyester B.
m polyester film B1 was obtained. The retardation value of the film could not be measured.

Example 1 30 parts of dipentaerythritol hexaacrylate, 4 parts
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, and a methacrylimide copolymer containing a quaternary ammonium salt group as an antistatic agent in a ratio of 95: 5. Is blended in a weight ratio of, and on one surface of the polyester film A1,
Apply so that the thickness after curing becomes 2μm, 120W / c
m high-pressure mercury lamp with energy of 100 m
Irradiated at 15 mm for 15 seconds to form a cured film. And
An acrylic pressure-sensitive adhesive was applied on the surface opposite to the surface on which the cured film was applied to obtain a laminated film.

Example 2 A laminated film was obtained in the same manner as in Example 1 except that an abrasion-resistant cured film was formed so that the thickness after curing became 1 μm.

Example 3 A laminated film was obtained in the same manner as in Example 1, except that the polyester film A1 was changed to the polyester film A2.

Example 4 Example 1 was repeated except that the polyester film A1 was changed to the polyester film A5, and the methacrylimide copolymer containing a quaternary ammonium salt group was not added to the active energy ray-curable resin composition as an antistatic agent. In the same manner as in Example 1, a laminated film was obtained.

Comparative Example 1 A laminated film was obtained in the same manner as in Example 1 except that no antistatic agent was added.

Comparative Example 2 In Example 1, except that no cured film was formed,
A laminated film was obtained in the same manner as in Example 1.

Comparative Example 3 A laminated film was obtained in the same manner as in Example 1, except that the polyester film A1 was changed to the polyester film A3. However, the entire film was wrinkled, which was at a practically problematic level.

Comparative Example 4 A laminated film 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 5 A laminated film was obtained in the same manner as in Example 1, except that the polyester film A1 was changed to the polyester film B1.

Tables 1 and 2 show the results of Examples 1 to 4 and Comparative Examples 1 to 5.

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[Table 1]

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[Table 2]

Production Example 9 (Polyester C) In Production Example 1, instead of the ethylene glycol slurry containing 0.1 part of silica particles having an average particle size of 1.54 μm, silica particles having an average particle size of 1.54 μm were added. Polyester C was obtained in the same manner as in Production Example 1, except that an ethylene glycol slurry containing 075 parts was used. The content of the silica particles of the polyester C was 0.075% by weight.

Production Example 10 (Polyester D) In Production Example 1, silica particles having an average particle size of 1.54 μm were replaced with 0.1% silica particles containing 0.1 part of silica particles having an average particle size of 1.54 μm. Polyester D was obtained in the same manner as in Production Example 1, except that an ethylene glycol slurry containing 2 parts was used. The content of the silica particles of the polyester D was 0.2% by weight.

Production Example 11 (Polyester film C) A 25 μm thick film was produced in the same manner as in Production Example 3 except that Polyester A was changed to Polyester C.
m of polyester film C was obtained. The retardation value of the film was 700 nm.

Production Example 12 (Polyester film D) A 25 μm thick film was produced in the same manner as in Production Example 3 except that polyester A was changed to polyester D.
m polyester film D was obtained. The retardation value of the film was 700 nm.

Example 5 A laminated film was obtained in the same manner as in Example 1 except that the polyester film A1 was changed to the polyester film C, and the following coating agent for a cured film was used. As the coating agent for the cured film, the coating agent used in Example 1 (a mixture of the active energy ray-curable resin composition and the antistatic agent) and the linear dimethylpolysiloxane gum were blended in a weight ratio of 95: 5. The coating agent prepared in this way was used.

Example 6 A laminated film was obtained in the same manner as in Example 5, except that an abrasion-resistant cured film was formed so that the thickness after curing became 1 μm.

Example 7 A laminated film was obtained in the same manner as in Example 5, except that the following coating agent for a cured film was used. As the coating agent for the cured film, the coating agent used in Example 1 (a mixture of the active energy ray-curable resin composition and the antistatic agent)
And a linear dimethylpolysiloxane gum in a weight ratio of 98: 2.

The results of Examples 5 to 7 are shown in Tables 3 and 4.

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[Table 3]

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[Table 4]

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According to the present invention described above, the liquid crystal display panel has excellent characteristics such as excellent handleability, easy inspection of the liquid crystal display panel with optical evaluation, and excellent prevention of dust adherence to the liquid crystal display panel. And a liquid crystal display panel surface protective film.

Claims (9)

[Claims] 1. A liquid crystal display panel surface protective film used by being adhered to the surface of a polarizing plate or a phase difference plate of a liquid crystal display plate, wherein one of a biaxially oriented polyester film having a thickness of 5 to 50 μm is used. The biaxially oriented polyester film has a retardation value of 30 to 10,000 nm, and is formed of a laminated film having a wear-resistant layer provided on one surface and an adhesive layer provided on the other surface. The layer has a surface resistivity of less than 1 × 10 ¹⁰ Ω, and the laminated film has a total light transmittance of 80% or more. 2. The film according to claim 1, wherein the abrasion-resistant layer comprises an active energy ray-curable resin. 3. The film according to claim 1, wherein abrasion resistance is provided via an antistatic layer. 4. The film according to claim 1, wherein the abrasion-resistant layer contains an antistatic agent. 5. The film according to claim 1, wherein the abrasion-resistant layer contains a silicone compound. 6. The film according to claim 1, wherein the coefficient of friction of the wear-resistant layer with respect to the polyester film is 0.3 or less. 7. The wear-resistant layer having a surface roughness (Ra) of 0.0
The film according to any one of claims 1 to 6, which has a thickness of 3 µm or less. 8. The pressure-sensitive adhesive layer is composed of at least one selected from the group consisting of an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a block copolymer-based pressure-sensitive adhesive, a polyisobutylene-based pressure-sensitive adhesive and a silicone-based pressure-sensitive adhesive. The film according to any one of claims 1 to 7. 9. The film according to claim 1, wherein a release film is laminated on the surface of the adhesive layer.