JP2001324603A - Biaxially oriented polyester film for antireflection of cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film for antireflection of a cathode ray tube, having excellent scratch resistance, processability, dimensional stability and transparency. SOLUTION: The biaxially oriented polyester film for antireflection of a cathode ray tube has 1.394 to 1.400 g/cm3 density, 1.490 to 1.500 refractive index (Nz) in the thickness direction, 1.650 to 1.690 refractive index (Ny) in the width direction and <=2.0% thermal shrinkage in the longitudinal direction at 150 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base polyester film used for a CRT antireflection film laminate, and more particularly, to a CRT antireflection film excellent in processability and scratch resistance. The present invention relates to a base polyester film used for a laminate.

[0002]

2. Description of the Related Art In recent flat panel displays, an antireflection process (for example, a sputtering method or a wet coating method) is applied to the outermost surface of an image display section in order to prevent reflection from external light. The CRT anti-reflection film laminate has a configuration in which a surface hardened layer is provided on one side of a transparent substrate, and then an anti-reflection layer is provided, and an adhesive layer is provided on the opposite side, and the adhesive layer surface is attached to the surface of the CRT. . As the transparent base material, a plastic film is used from the viewpoint of processability. Further, among the plastic films, a biaxially oriented polyester film is suitably used as a transparent substrate used in a CRT antireflection film laminate because of its excellent transparency, dimensional stability, and chemical resistance.

[0003] An antireflection film laminate bonded to the surface of a cathode ray tube is required to have excellent scratch resistance, workability, dimensional stability, and transparency. In particular, a method of providing a surface hardened layer on various easily adhesive films in order to improve scratch resistance is disclosed in, for example, JP-A-62-263.
237 and JP-A-63-147798.

However, when these are used for a CRT anti-reflection film laminate, none of them have satisfied scratch resistance, workability, dimensional stability and transparency.

[0005]

The causes are considered as follows. That is, it is important to provide a surface hardened layer and have a certain thickness in order to provide a sufficient protective function basically in order to provide good protection of the cathode ray tube.

However, if the thickness of the hardened surface layer is too large, the sharpness of the cathode ray tube tends to be impaired, which is not always optically desirable, and also causes problems such as cracks in the hardened surface layer. . On the other hand, if the surface hardened layer is too thin, the scratch resistance is insufficient. For the above reasons, the thickness of the surface hardened layer is restricted to some extent, and it has been necessary to improve the scratch resistance of the base film itself.

That is, an object of the present invention is to solve the above-mentioned conventional problems, and to provide a biaxially oriented polyester film for anti-reflection of a Braun tube having excellent scratch resistance, workability, dimensional stability and transparency. To provide.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a biaxially oriented polyester film for anti-reflection of a cathode ray tube, which can solve the above-mentioned problems, comprises: It is as follows.

In the first invention, the density is 1.394 to 1.4.
00g / cm ³ , a refractive index (Nz) in the thickness direction of 1.490 to 1.500, a refractive index (Ny) in the width direction of 1.650 to 1.690, and a longitudinal length at 150 ° C. A biaxially oriented polyester film for CRT antireflection, wherein the heat shrinkage in the direction is 2.0% or less.

According to the second invention, the difference between the maximum value and the minimum value of the refractive index (Nz) in the thickness direction in the film width direction is 0.0.
The biaxially oriented polyester film for anti-reflection of a Braun tube according to the first invention, wherein the film is not more than 05.

According to a third aspect, the difference between the maximum value and the minimum value of the refractive index (Nz) in the thickness direction in the film width direction is 0.0.
The biaxially oriented polyester film for anti-reflection of a CRT according to the second invention, wherein the film is 02 or less.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a cathode ray tube is
A so-called cathode ray tube (CRT :) that converts an electric signal into an optical image
(cathode ray tube), which creates an electron beam in a vacuum-sealed glass tube and changes its direction according to an externally applied signal.
It is a general term for those used for display screens such as computer displays, oscilloscopes, and radars. In addition, antireflection means prevention of reflection of external light on a cathode ray tube.

The biaxially oriented polyester film for CRT antireflection of the present invention is used as a base material of a CRT antireflection film laminate as described above. The CRT anti-reflection film laminate has a configuration in which a surface hardened layer and then an anti-reflection layer are provided on one surface of a transparent base material, and an adhesive layer is provided on the opposite surface, and the adhesive layer surface is adhered to the surface of the CRT.

The biaxially oriented polyester film of the present invention is obtained by biaxially stretching a polyester sheet or film in an unstretched state in the longitudinal direction and the width direction, and obtains a biaxially oriented pattern by wide-angle X-ray diffraction. Means

The polyester resin as a raw material of the biaxially oriented polyester film is a general term for a polymer resin having an ester bond as a main bonding chain of a main chain. Preferred polyester resins include at least one selected from ethylene terephthalate, ethylene-2,6-naphthalate, butylene terephthalate, ethylene-α, β-bis (2-chlorophenoxy) ethane-4,4-dicarboxylate, and the like. Is a main repeating unit. These repeating units may be used alone or in combination of two or more. Among them, a polyethylene terephthalate resin containing ethylene terephthalate as a main repeating unit is particularly preferable when quality, economy and the like are comprehensively determined.

Further, in the polyester resin, various additives such as an antioxidant, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, and the like may be used as needed, as long as the effects of the present invention are not impaired. Antistatic agents, electrostatic adhesion improvers (glycol-soluble alkali metal salts, alkaline earth metal salts, etc.) and the like may be added.

It is preferable that the biaxially oriented polyester base film of the present invention does not substantially contain particles from the viewpoint of transparency. Substantially free of particles
For example, in the case of inorganic particles, it means a particle content below the detection limit when quantitatively analyzed by X-ray fluorescence analysis.

The biaxially oriented polyester film of the present invention may be provided with a coating layer on at least one surface of the film or a corona treatment or the like in order to impart adhesiveness, antistatic property, slipperiness, release property and the like of the film. Surface treatment may be performed.

Further, the biaxially oriented polyester film of the present invention may be formed by adding a copolymerized polyester resin to both sides of an unstretched polyester film or a uniaxially stretched polyester film in order to improve the adhesion between the cured film and the adhesive layer. It is preferable to provide an easy-adhesion layer composed of a composition mainly composed of a polyurethane resin and inert particles, and then to laminate by a so-called in-line coating method of stretching and heat-setting at least in one axis direction.

Inert particles (eg, silica particles, silica-alumina composite oxide particles,
Glass filler, etc.) to form irregularities on the surface of the easy-adhesion layer, so
Scratch resistance can be provided. For this reason, since it is not necessary to contain inert particles in the biaxially oriented polyester base film, the haze value of the film is 1.0
% Or less, and is extremely effective in obtaining a highly transparent film having a total light transmittance of 90% or more.

In the above-mentioned easy-adhesion layer, the copolymer polyester resin alone has sufficient adhesiveness to the polyester base film, but does not adhere to the acrylic resin generally used for the surface hardened layer and the pressure-sensitive adhesive layer. Insufficiency. Further, although the polyurethane resin alone has excellent adhesiveness with an acrylic resin, the adhesiveness with a polyester base film is insufficient.

As the copolymerized polyester resin (A), those containing a branched glycol component are preferable.
As the polyurethane resin (B), those containing a blocked isocyanate group are preferred. The weight ratio of the resin (A) to the resin (B) is (A) :( B) = 90: 10 to 1
0:90 is preferred, and more preferably (A) :( B) =
80:20 to 20:80.

The coating on the substrate film can be performed by any known method. For example, a reverse roll coating method, a gravure coating method, a kiss coating method, a roll brushing method, a spray coating method, an air knife coating method, a wire bar bar coating method, a pipe doctor method, a die coating method, an impregnation coating method, a curtain coating method and the like can be mentioned. These methods may be performed alone or in combination.

The biaxially oriented polyester film of the present invention needs to have a density of 1.394 to 1.400 g / cm ³ . If the density exceeds 1.400 g / cm ³ , since the plastic deformation of the film due to the scratches generated on the surface of the hardened layer has a weak elastic recovery force with time, the hardened layer remains. Therefore, when the antireflection film laminate is adhered to a CRT monitor, the scratched portion is unfavorably observed as glare on the CRT surface. When the density is not more than 1.400 g / cm ³ , the healing power of the wound is good. However, from the viewpoint of workability of the film, when the density is less than 1.394 g / cm ³ , when the film passes through a process involving heating during post-processing such as an antireflection treatment or a surface-hardened layer, wrinkles may occur. It is not preferable because curling occurs and flatness is easily deteriorated.

However, even if the density is less than 1.394 g / cm ³ , the temperature at 150 ° C. can be adjusted by optimizing the heat setting conditions (temperature, time, etc.) and relaxation treatment (treatment temperature, relaxation rate, etc.) during film production. 1. Heat shrinkage in the longitudinal direction
By setting the content to 0% or less, preferably 1.5% or less, it is possible to reduce the deterioration of processing characteristics such as the occurrence of wrinkles and curls and the deterioration of flatness.

The biaxially oriented polyester film of the present invention has a heat shrinkage in the longitudinal direction at 150 ° C. of 2.0.
% Or less, and preferably 1.5% or less. 1. Heat shrinkage in the longitudinal direction at 150 ° C.
If it exceeds 0%, it is not preferable because wrinkles, curls, irregularities in flatness, and the like are generated when passing through a process involving heating during post-processing such as providing an antireflection treatment or a surface hardened layer.

The biaxially oriented polyester film of the present invention has a refractive index (Ny) in the width direction of 1.650 to 1.690.
, And preferably 1.665 to 1.65.
685. When Ny exceeds 1.690, the healing power of the flaw formed in the surface hardened layer becomes weak. On the other hand, 1.65
If it is less than 0, the flatness will deteriorate.

Further, the biaxially oriented polyester film of the present invention has a refractive index (Nz) in the thickness direction of 1.490-1.4.
Must be 1.500, preferably 1.4
91 to 1.496. When Nz exceeds 1.500, the film strength is reduced and the flatness is deteriorated, which is not preferable. On the other hand, when Nz is less than 1.490, the recovery of a flaw formed on the surface hardened layer is weakened, which is not preferable.

Further, in the biaxially oriented polyester film of the present invention, the difference between the maximum value and the minimum value of the refractive index (Nz) in the thickness direction in the width direction of the film is preferably 0.005 or less, particularly preferably. 0.002 or less.

If the difference between the maximum value and the minimum value of the refractive index (Nz) in the thickness direction in the film width direction exceeds 0.005, differences in optical characteristics, processing characteristics, and the like in the film width direction tend to occur. In particular, in recent years, when the cathode ray tube has been increased in size, and the difference in physical properties has become a problem when the product width is widened, it is preferable to reduce the physical property difference in the width direction of the film.

The thickness of the biaxially oriented polyester film of the present invention is preferably in the range of 100 to 200 μm from the viewpoint of proper processing as a CRT antireflection film and explosion proof properties.

The CRT anti-reflection film laminate has the above-mentioned biaxially oriented polyester film as a base material, and has a hardened surface layer provided on one surface thereof for the purpose of improving scratch resistance.

The film-forming component of the curable resin composition used for the surface-cured layer is preferably one having an acrylate-based functional group, for example, a polyester resin, a polyether resin or an acrylic resin having a relatively low molecular weight. Oligomers or prepolymers such as (meth) acrylates of polyfunctional compounds such as epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and polyhydric alcohols, and ethyl (meth) ) Acrylate, ethylhexyl (meth) acrylate, monofunctional monomers such as styrene, methylstyrene, N-vinylpyrrolidone and polyfunctional monomers, for example, trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropy Glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate,
Dipentaerythritol hexa (meth) acrylate,
Those containing relatively large amounts of 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate and the like can be used.

The thickness of the surface hardened layer is 0.5 to 10 μm
It is preferred that When the thickness is less than 0.5 μm, the scratch resistance tends to be insufficient, and when the thickness is more than 10 μm, the cured film tends to be brittle, and the cured film is liable to crack when bent, which is not preferable.

As the method of curing the curable resin composition, a usual curing method, that is, a method of curing by heating, irradiation with an electron beam or ultraviolet rays can be used. For example,
In the case of electron beam curing, 50 to 1000 keV, preferably emitted from various electron beam accelerators such as Cockloft-Walton type, Handie graph type, Resonant transformation type, Insulating core transformer type, Linear type, Dynamitron type, High frequency type, etc. Is 100-3
An electron beam having an energy of 00 keV is used. In the case of ultraviolet curing, ultraviolet rays emitted from light rays such as an ultrahigh-pressure mercury lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp can be used.

Further, an antireflection layer is provided on the surface hardened layer for the purpose of preventing reflection of external light. It is preferable that the antireflection layer be a single layer or a laminate of two or more materials having a refractive index different from the refractive index of the surface hardened layer. In the case of a single-layer structure, it is preferable to use a material having a smaller refractive index than the surface hardened layer. In the case of a multi-layer structure of two or more layers, the layer adjacent to the surface hardened layer uses a material having a higher refractive index than the surface hardened layer, and the upper layer has a smaller refractive index than this. It is good to choose the material. The material constituting such an anti-reflection layer is not particularly limited, whether it is an organic material or an inorganic material, as long as it satisfies the above-mentioned refractive index relationship. For example, Ca
F ₂ , MgF ₂ , NaAlF ₄ , SiO ₂ , ThF ₄ , Zr
O ₂ , Nd ₂ O ₃ , SnO ₂ , TiO ₂ , CeO ₂ , ZnS,
It is preferable to use a dielectric such as In ₂ O ₃ .

The method of providing the anti-reflection layer includes a vacuum deposition method,
A dry coating process such as a sputtering method, a CVD method, or an ion plating method, or a wet coating process such as a gravure method, a reverse method, or a die method may be used.

Prior to the lamination of the antireflection layer, known pretreatments such as a corona discharge treatment, a plasma treatment, a sputter etching treatment, an electron beam irradiation treatment, an ultraviolet irradiation treatment, a primer treatment, and an easy adhesion treatment are performed. A surface treatment may be applied to the surface hardened layer.

Further, an adhesive layer is provided on the surface of the anti-reflection film opposite to the anti-reflection layer for adhesion to the cathode ray tube, opposite to the film surface on which the surface hardened layer and the anti-reflection layer are formed. As the pressure-sensitive adhesive, acryl-based, silicone-based, rubber-based and the like can be used, and among them, acrylic-based is preferable in terms of heat resistance and adhesive strength.

Next, the method for producing the biaxially oriented polyester film of the present invention will be described in detail with reference to polyethylene terephthalate (PET) as an example, but is not necessarily limited thereto.

PE substantially free of inert particles
After drying the T chips in a vacuum, the melted PET is supplied to an extruder, and the molten PET is extruded into a sheet from an extruder with a T die, and the sheet is adhered and solidified on a cooled casting drum while applying an electrostatic charge to the unstretched film. Get.

The unstretched film is stretched at a stretching temperature of 80 to 1
The film is stretched at 00 ° C. in one step in the longitudinal direction, more preferably in two or more steps, 2 to 5 times to obtain a uniaxially oriented PET film. Next, an aqueous coating solution is applied to both sides of the film as required. Further, the end of the film is gripped with a clip, guided to a hot-air zone heated to 80 to 180 ° C., stretched 2.0 to 5.0 times in the width direction after drying.

Subsequently, the mixture was led to a heat-setting treatment zone, where 12
A heat setting treatment is performed at 0 to 240 ° C. for 1 to 60 seconds to complete the crystal orientation. During this heat-setting treatment step, a relaxation treatment of 3 to 10% may be performed in the width direction and / or the longitudinal direction as necessary.

In the above production method, one of the means for simultaneously satisfying the density, Nz, Ny, and the thermal shrinkage in the longitudinal direction at 150 ° C. specified in the present invention is as follows. It is particularly effective that the temperature difference (BA) from the film surface temperature B during the fixing treatment is 0 to 50 ° C, preferably 0 to 40 ° C.

In order to make the difference between the maximum value and the minimum value of Nz in the film width direction 0.005 or less, the temperature at the center of the film is made higher than the temperature at the edge of the film in the transverse stretching step. It is more preferable that the temperature difference between the central portion and the end portion of the film is 3 ° C. or more, and more preferably 5 ° C. or more. Here, the edge of the film indicates a position of 25% and 75% of the entire width of the film, and the center indicates a position of 50% of the entire width of the film.

Further, the temperature difference in the width direction of the film during the heat setting treatment is preferably 0 to 3.0 ° C., particularly preferably 0 to 1.0 ° C.
It is effective to make the difference between the maximum value and the minimum value of 0.005 or less.

The measurement of the film surface temperature was performed by attaching a micro thermocouple to the film surface.

[0048]

EXAMPLES Next, the biaxially oriented polyester film of the present invention will be described in detail with reference to examples, but it is needless to say that the invention is not limited thereto. “Parts” used in Examples and Comparative Examples means “parts by weight” unless otherwise specified. The evaluation of the characteristic values used in this specification was based on the following method.

(1) Density A film specimen (5 to 7 mm × 5 to 7 mm) and several floats of known density values were placed in a density gradient tube (inner diameter: 46.5).
mm, length: 1000 mm, adjusting liquid: adjusted from water and calcium nitrate), and after 24 hours, read the ratio of the position of the test piece as viewed from the upper and lower floats of the test piece, and calculated the value. The density was determined from the following equation. Density (g / cm ³ ) = A-[(xa) / (ba)]
× (AB) A: Density (g / cm) of the float located under the test piece
³ ) B: Density (g / cm) of the float located above the test piece
³ ) x: scale of the position of the test piece (mm, average value of n = 3) a: scale of the position of the float below the test piece (mm) b: scale of the position of the float above the test piece (mm) mm)

(2) Refractive index (Nz) in thickness direction and refractive index (Ny) in width direction A polarizing plate is attached to an eyepiece using an Abbe refractometer 4T manufactured by Atago Co., Ltd., and the direction of the polarizing plate and the direction of the film. Are adjusted respectively, the refractive index (Nz) in the film thickness direction,
The refractive index (Ny) in the width direction was measured. Jodomethane was used as the intermediate liquid. The measurement of the refractive index in each direction was performed for each sample on both sides of the film at n = 3, and the average value was defined as the refractive index in each direction. The width direction here is
The direction perpendicular to the roll unwinding direction, the longitudinal direction,
The direction parallel to the unwinding direction of the roll.

(3) Maximum value and minimum value of the refractive index (Nz) in the thickness direction in the film width direction In a straight line direction perpendicular to the roll unwinding direction, 10, 20, 30, 40, 50 relative to the entire film width. , 60,
Sampling was performed at 70, 80, and 90% positions. Nz was measured on both sides of the film at n = 3 for each sample, and the average value was defined as Nz at each position. The maximum value and the minimum value of the average value of Nz at each position were obtained.

(4) Heat shrinkage in the longitudinal direction at 150 ° C. [HS150 (MD)] A film is cut into a size of 10 mm in width and 250 mm in length along a direction in which the long side (250 mm) coincides with the longitudinal direction. Markings were made at intervals of 200 mm, and the interval A was measured at a constant tension of 5 g. Then, it was left at 150 ° C. for 30 minutes in a 150 ° C. atmosphere oven without load. After removing the film from the oven and cooling to room temperature,
Was determined under a constant tension of 5 g, and the heat shrinkage was determined by the following equation. The thermal shrinkage in the longitudinal direction at 150 ° C. of the film was measured at 100 mm intervals in the film width direction, the average value was rounded off to the third decimal place, and rounded to the second decimal place. The intervals A and B were read by a ruler at intervals of 0.25 mm. Heat shrinkage (%) = [(AB) / A] × 100

(5) Scratch resistance A surface hardened layer is provided on the base film, and the pencil hardness is JIS-K
In accordance with 5400, pencils of various hardnesses were applied perpendicularly to the surface of the surface hardened layer, scratched with a load of 1 kg, and those having a hardness of 3H or more when scratches occurred were evaluated as ○, and those of 2H or less were evaluated as x.

(6) Processing Characteristics The occurrence of wrinkles, curls, and irregularities in flatness when the antireflection layer was provided on the base film were visually evaluated. ：: no wrinkles, curls, and irregularities in flatness ○: almost no wrinkles, curls, and irregularities in planarity ×: wrinkles, curls, and irregularities in planarity

(7) Haze value Haze value was measured using a haze meter (Model TC-H3DP manufactured by Tokyo Denshoku Industries Co., Ltd.) according to JIS-K7105.

(8) Intrinsic viscosity The intrinsic viscosity was determined from the solution viscosity at 30 ° C. in a mixed solvent of 1,1,2,2-tetrachloroethane / phenol (weight ratio: 40/60).

Example 1 (1) Preparation of coating solution The coating solution used in Example 1 was prepared according to the following method. 95 parts of dimethyl terephthalate, 95 parts of dimethyl isophthalate, 35 parts of ethylene glycol, 145 parts of neopentyl glycol, 0.1 part of zinc acetate and 0.1 part of antimony trioxide are charged into a reaction vessel, and the ester is added at 180 ° C. for 3 hours. An exchange reaction was performed. Next, 6.0 parts of 5-sodium isophthalic acid was added, and
After performing the esterification reaction over time, the polycondensation reaction is performed at 250 ° C. under reduced pressure (13.3 to 0.267 hPa) for 2 hours to obtain a polyester resin having a molecular weight of 19,500 and a softening point of 60 ° C. Was.

30% of the obtained polyester resin (A)
6.7 parts of an aqueous dispersion and 40.0% of a 20% aqueous solution of a self-crosslinkable polyurethane resin (B) containing an isocyanate group blocked with sodium bisulfite (product name: Elastron H-3, manufactured by Daiichi Kogyo Seiyaku). Parts, 0.5 part of elastron catalyst (Cat64, manufactured by Daiichi Kogyo Seiyaku) and 47.8 parts of water.
Of isopropyl alcohol and 5 parts of isopropyl alcohol, respectively, and further added 1.10% aqueous solution of anionic surfactant.
0 parts, 20% of spherical silica particles (manufactured by Nissan Chemical Industries, Ltd .: Snowtex OL, average particle size 40 nm by SEM method)
5.0 parts of an aqueous dispersion was added to obtain a coating liquid.

(2) Production of Biaxially Oriented Polyester Film Polyethylene terephthalate (PE) having an intrinsic viscosity of 0.62 dl / g and substantially no inert particles
T) After sufficiently drying the resin pellets in a vacuum, supply them to an extruder, melt them at 285 ° C, extrude them into a sheet shape from a T die, and make them electrostatically adhere to a cooling roll using electrodes to which DC high voltage is applied. 1700 μm unstretched PET
A film was obtained.

This unstretched PET film was heated to 75 ° C. by a ceramic roll, and was further heated to a surface temperature of 700 ° C.
The film was stretched 3.4 times in the machine direction while heating using four infrared heaters at a temperature of 4 ° C. Next, the coating liquid described in the above (1) was applied to both sides of the longitudinally uniaxially stretched PET film by a reverse roll method. After coating, the longitudinally uniaxially stretched PE
After gripping both ends of the T film with a clip, feeding the film into a tenter, preheating and drying at 90 ° C., and then 4.0 in the horizontal direction.
It was stretched twice.

In the transverse stretching step, the temperature difference between the edge of the film (positions of 25% and 75% with respect to the entire width of the film) and the center (position of 50% with respect to the entire width of the film) is 5 ° C. (central part>
An infrared heater was used to heat the central portion (at the position of 50% with respect to the entire width of the film) so as to form an edge portion. The film surface temperature at the end of stretching was 170 ° C, and the film surface temperature at the start of heat setting was 200 ° C. Subsequently, a 5% heat-setting treatment was performed in the width direction at 210 ° C., and a 1% relaxation treatment was performed in the longitudinal direction at 150 ° C. In the heat treatment process, the edge of the film (25% of the entire width of the film)
And 75%) were heated in three stages by an infrared heater, and the temperature difference between the center and the end was set to 1 ° C. or less.
In this way, the thickness 125 μm and the coating layer thickness 0.1
A 5 μm laminated biaxially oriented PET film was obtained. Table 1 shows the physical properties.

Next, on one side of the laminated biaxially oriented PET film, an ultraviolet curable resin (EXG, manufactured by Dainichi Seika) made of a mixture of polyester acrylate and polyurethane acrylate was applied as a UV curable resin to a thickness of 5 μm.
(During drying) was applied by a gravure reverse method, and the solvent was dried. Thereafter, the resin was passed under a 160 W ultraviolet irradiation device at a speed of 10 m / min to cure the ultraviolet curable resin and form a surface cured layer.

Next, TiO is sequentially formed on the surface hardened layer.
₂ thin film (refractive index: 2.30, film thickness 15 nm), SiO ₂ thin film (refractive index: 1.46, film thickness 29 nm), TiO ₂ thin film (refractive index: 2.30, film thickness 109 nm), SiO ₂ thin film (Refractive index: 1.46, film thickness: 87 nm) to form an antireflection layer.

In order to form a TiO ₂ thin film, a direct current magnetron sputtering method is used by using titanium as a target, the degree of vacuum is 0.27 Pa, and Ar gas is used as a gas.
0 sccm and O ₂ gas were flowed at a flow rate of 80 sccm.
Further, a cooling roll at 0 ° C. was provided on the back surface of the substrate to cool the plastic film. At this time, a power of 7.8 W / cm ² was supplied to the target, and the dynamic rate was 23 nm · m / min.

In order to form an SiO ₂ thin film, silicon is used as a target and the degree of vacuum is 0.27 Pa, and Ar gas is used as a gas by DC magnetron sputtering.
00 sccm and O ₂ gas were flowed at a flow rate of 80 sccm. In addition, a cooling roll of 0 ° C. is provided on the back of the substrate,
The plastic film was cooled. At this time, a power of 7.8 W / cm ² was supplied to the target, and the dynamic rate was 23 nm · m / min. In this way,
A CRT antireflection film laminate was obtained. Table 1 shows the physical properties.

Example 2 In the same manner as in Example 1, the coating solution described in Example 1 was applied to both sides of a vertically uniaxially stretched PET film by a reverse roll method. After the application, subsequently, both ends of the longitudinally uniaxially stretched PET film are gripped with clips, fed into a tenter, preheated and dried at 90 ° C., and then the stretching start temperature is set at 120 ° C.
C., the stretching end temperature was 145 ° C., and the film was stretched 4.0 times in the transverse direction. Subsequently, a 5% heat-setting treatment was performed in the width direction at 210 ° C., and a 1% relaxation treatment was performed in the longitudinal direction at 150 ° C. In Example 2, heating of the film edge was not performed in the heat setting process. The temperature difference between the center and the edge of the film was 4 ° C. or more. In the same manner as in Example 1, a surface hardened layer and an antireflection layer were provided. Table 1 shows the physical properties.

Comparative Example 1 A biaxially stretched PET film was prepared in the same manner as in Example 1 except that the heat setting temperature was 230 ° C., and then the relaxation treatment was not performed in the longitudinal direction. In the same manner as in Example 1, a surface hardened layer and an antireflection layer were provided. Table 1 shows the physical properties.

Comparative Example 2 Both ends of a longitudinally stretched sheet obtained in the same manner as in Example 1 were gripped with clips, fed into a tenter, preheated at 90 ° C., and then stretched at a starting temperature of 120 ° C. The end temperature was 145 ° C., and the film was stretched 4.0 times in the transverse direction. Then, 2
A 5% heat setting treatment was performed in the width direction at 10 ° C. No longitudinal relaxation treatment was performed. In the heat treatment step, the edge of the film (positions of 25% and 75% with respect to the entire width of the film) was heated in three stages by an infrared heater, and the temperature difference between the center and the edge was 1 ° C. or less. In the same manner as in Example 1, a surface hardened layer and an antireflection layer were provided. Table 1 shows the physical properties.

[0069]

[Table 1]

[0070]

As described above, the biaxially oriented polyester film for CRT antireflection according to the present invention controls molecular orientation and crystallization, and can be used to control the specific film density, refractive index (Nz) in the thickness direction, and width direction. Index of refraction (Ny), and 15
Since it has a heat shrinkage in the longitudinal direction at 0 ° C., it has excellent scratch resistance, workability, dimensional stability, and transparency. In particular, since the biaxially oriented polyester film of the present invention has excellent scratch resistance of the film itself,
There is the advantage that the optical properties and the scratch resistance of the CRT antireflection film laminate are excellent.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) B29L 7:00 C08L 67:00 C08L 67:00 G02B 1/10 A F term (Reference) 2K009 AA03 AA15 BB24 CC02 CC03 CC06 CC23 CC24 CC33 CC34 CC35 DD02 DD03 DD04 DD07 DD08 4F071 AA43 AA80 AA82 AF31 AF31Y AF61Y AH16 BB08 BC01 4F210 AA24 AG01 AH33 QA02 QA03 QC05 QC06 QD08 QG01 QG18 5C058 AA01 BA30 DA01

Claims (3)

[Claims] 1. Density of 1.394 to 1.400 g / cm
³ , and the refractive index (Nz) in the thickness direction is 1.490 to
1.500, the refractive index (Ny) in the width direction is 1.650
1. A biaxially oriented polyester film for CRT antireflection, wherein the heat shrinkage in the longitudinal direction at 150 ° C. is 2.0% or less. 2. The biaxially oriented polyester for CRT antireflection according to claim 1, wherein the difference between the maximum value and the minimum value of the refractive index (Nz) in the thickness direction in the film width direction is 0.005 or less. the film. 3. The biaxially oriented polyester for CRT antireflection according to claim 2, wherein the difference between the maximum value and the minimum value of the refractive index (Nz) in the thickness direction in the film width direction is 0.002 or less. the film.