JP2003105267A - Coating material composition and antistatic hard coat film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating material composition capable of continuously and uniformly forming a hard coat layer excellent in antistaticity, transparency, scratch resistance and chemical resistance, and to provide an antistatic hard coat film having the hard coat layer obtained by coating the composition. SOLUTION: The coating material composition comprises at least an ionizing radiation-curable resin, an ultrafine particle of a metal oxide and a solvent. The ultrafine particle has an average particle size of <=0.3 μm and is obtained by doping antimony to a metal oxide such as tin oxide (SnO2 ) and zinc oxide (ZnO). The solvent has dielectric constant of >=9.0 and a boiling point of >=90 deg.C but <180 deg.C. The hard coat layer is obtained by coating a film with the coating composition comprising 100 pts.wt. total of the ionizing radiation-curable resin and the ultrafine particle of the metal oxide and >=30.0 pts.wt. of the solvent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coating composition for forming a hard coat layer on a support and an antistatic hard coat film having a hard coat layer formed by applying the coating composition.

[0002]

2. Description of the Related Art Various display bodies such as liquid crystal displays, CRTs and plasma displays use a transparent plastic film which is hard-coated to protect the surface thereof. This transparent plastic film is
Due to its high volume resistivity, static electricity is easily applied to the contact surface due to friction, etc., and it does not leak, so it is produced due to dust adsorption present during the display assembly process and troubles in the process due to static electricity. The decrease in sex becomes a problem. Further, when actually used as a display, the visibility is remarkably lowered due to the adsorption of dust on the surface.

In order to improve these problems, it is common practice to impart antistatic performance with a surfactant or the like. In order to impart antistatic performance, kneading of an organic material with ion conductivity such as alkylamine halide into plastic or addition to paint and surface coating has been performed, but it depends on humidity. It has a high property, and there is a drawback that the performance is deteriorated especially under dry conditions.
In addition, it has been attempted to use an inorganic filler such as a metal powder, but the transparency is significantly lowered.

In Japanese Patent Laid-Open No. 10-235807, as an antistatic film having no humidity dependency and improved transparency, antimony, which is a metal oxide ultrafine particle of 0.5 μm or less, is used as a material for imparting antistatic property. There is disclosed one in which a paint prepared using doped zinc oxide (ZnO) and a solvent for preparing a paint, such as methanol, ethanol, or methyl ethyl ketone, is used. However, since the boiling point of the solvent is very low, the concentration change due to solvent volatilization is large, and
Uneven drying occurs due to solvent evaporation during the drying process,
Poor stable and continuous coatability.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a coating composition capable of continuously and uniformly forming a hard coat layer having excellent antistatic property, transparency, scratch resistance and chemical resistance, and the composition. It is intended to provide an antistatic hard coat film having a hard coat layer formed by coating.

[0006]

In view of the above situation, the present inventors have imparted antistatic performance without deteriorating the transparency, scratch resistance, and chemical resistance required for transparent protective films. The present invention has been completed by finding a coating composition capable of continuously and uniformly forming a coating layer.

The above objects of the present invention are: (1) at least an ionizing radiation curable resin, ultrafine metal oxide particles having an average particle size of 0.3 μm or less, and a solvent having a dielectric constant of 9.0 or more and a boiling point of 90 ° C. or more and less than 180 ° C. And a total of 100. of the ionizing radiation curable resin and the metal oxide ultrafine particles.
A coating composition containing 30.0 parts by weight or more of the solvent with respect to 0 parts by weight, (2) the ultrafine metal oxide particles are antimony-doped tin oxide (SnO ₂ ), described in (1) Coating composition, (3) the metal oxide ultrafine particles are antimony-doped zinc oxide (ZnO), the coating composition described in (1), (4) metal oxides in the solid content of the coating composition. The compounding ratio of the ultrafine particles is 15.0% by weight or more 70.
The coating composition according to any one of (1) to (3), which is less than 0% by weight, (5) on the film support, (1)
To (4) an antistatic hard coat film having a hard coat layer formed by applying the coating composition according to any one of (4) to (4), wherein the film support is triacetyl cellulose Achieved by an anti-hard coat film.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As a resin used for a hard coat layer, an ionizing radiation curable resin is used. The ionizing radiation curable resin is not particularly limited as long as it is a transparent resin that is cured by irradiation with electron beams or ultraviolet rays, and examples thereof include urethane acrylate resin, polyester acrylate resin and epoxy acrylate resin. Can be appropriately selected from among the above.

Preferable ones are those comprising a UV-curable polyfunctional acrylate having two or more (meth) acryloyl groups in the molecule. 2 in the molecule
Specific examples of the UV-curable polyfunctional acrylate having one or more (meth) acryloyl groups include neopentyl glycol di (meth) acrylate and 1,6-hexanediol di (meth) acrylate. , Trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol
Polyols such as rutri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, poly (meth) acrylate, bisphenol A diglycidyl ether
Ter's di (meth) acrylate, neopentyl glyco-
Ludiglycidyl ether di (meth) acrylate,
Epoxy (meth) acrylates such as di (meth) acrylates of 1,6-hexanediol diglycidyl ether, polyhydric alcohols and polyhydric carboxylic acids and / or their anhydrides, and (meth) acryl Urethane (meta) obtained by reacting a polyester (meth) acrylate, a polyvalent alcohol, a polyvalent isocyanate and a hydroxyl group-containing (meth) acrylate which can be obtained by esterification with an acid. ) Acrylate, polysiloxane poly (meth) acrylate and the like can be mentioned.

The above-mentioned polymerizable acrylates may be used alone or in combination of two or more, and the content thereof is based on the solid content of the ionizing radiation curable resin of the coating composition.
It is preferably 95.0 to 50.0% by weight. In addition to the above-mentioned polyfunctional acrylate, the content of 2-hydroxy (meth) acrylate is preferably 10.0% by weight or less based on the solid content of the ionizing radiation-curable resin in the hard coat layer coating material. −
Monofunctional acrylates such as hydroxypropyl (meth) acrylate and glycidyl (meth) acrylate can also be blended.

The hard coat layer may contain a polymerizable oligomer used for the purpose of adjusting hardness. Such oligomers include terminal (meth) acrylate polymethylmethacrylate, terminal styrylpoly (meth) acrylate, terminal (meth) acrylate polystyrene, terminal (meth) acrylate polyethyleneglycol. And terminal (meth) acrylate acrylonitrile-
Macromonomers such as styrene copolymer and terminal (meth) acrylate styrene- (meth) acrylate copolymer
The content thereof is preferably from 50.0 to the solid content of the ionizing radiation curable resin of the coating composition.
It is 5.0% by weight.

In the present invention, ultrafine metal oxide particles are contained for the purpose of imparting antistatic performance to the hard coat layer without impairing transparency. The average particle size of the metal oxide ultrafine particles is determined from the average particle size of the dynamic scattering method. In order not to impair the transparency, it is necessary to use ultrafine metal oxide particles having an average particle size of 0.3 μm or less, which is smaller than the wavelength of visible light. 0.1μ for higher transparency
It is preferably m or less. Moreover, in order to obtain a low surface resistivity, tin oxide (SnO ₂ ) doped with antimony is used.
Alternatively, zinc oxide (ZnO) is preferable. As the content of the metal oxide ultrafine particles, in the solid content of the coating composition,
It is preferably 15.0% by weight or more and less than 70.0% by weight. If the content is too low, a network between the metal oxide ultrafine particles cannot be formed and the antistatic performance is not exhibited, and if it is too high, the transparency and scratch resistance tend to decrease.

In the present invention, 30.0 parts by weight or more of a solvent having a dielectric constant of 9.0 or more and a boiling point of 90 ° C. or more and less than 180 ° C. is added to the coating composition. Such a solvent is described, for example, in a solvent handbook (Kodansha, 1991). When the dielectric constant is low, the ultrafine metal oxide particles agglomerate and the transparency is impaired. Further, when the boiling point of the solvent is low, the concentration change due to the solvent volatilization is large, so that uneven drying occurs due to the solvent volatilization in the drying step, and stable continuous coating property is poor. When the boiling point is high, the load on the drying step is large, the productivity is lowered, and the transparent plastic film substrate is deformed, thereby impairing the uniformity of the film. Therefore, the boiling point of the solvent is 90 ℃ or less 180 ℃
Must be less than.

In the present invention, in order to obtain coating suitability of the coating composition, the solid content concentration of the coating composition is preferably 15.0% by weight or more and less than 65.0% by weight. When the solid content is low, the viscosity of the coating composition tends to decrease, and the unevenness in drying of the coated surface tends to occur remarkably. When the solid content is high, the viscosity of the coating composition becomes high, and it tends to be difficult to obtain uniformity of the coated surface.

Further, in order to improve the performance, an antifoaming agent, a leveling agent, an antioxidant,
It may contain an ultraviolet absorber, a light stabilizer, a polymerization inhibitor and the like.

In order to impart antiglare property to the coating layer, organic or inorganic fine particles such as silica particles and resin beads such as acrylic resin, silicon resin, urethane resin, etc. are used within a range that does not change the effect of the present invention. It can also be added.

The antistatic hard coat film of the present invention is obtained by coating the above-mentioned coating composition on a film support. The support used in the antistatic hard coat film of the present invention is preferably a transparent sheet or film, for example, polyester film, polyethylene film, polypropylene film, cellophane film,
Diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film,
Polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, polystyrene film, polycarbonate film, polymethylpentel film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, Examples thereof include polyimide film, fluororesin film, nylon film, acrylic film and the like.

In the antistatic hard coat film of the present invention, a triacetyl cellulose film (TAC film), which is widely used as a polarizing plate member for liquid crystal displays, is used because it has no optical anisotropy. It is preferable. Since the TAC film is usually formed by a solution casting method and has poor flatness and high transparency, it is very difficult to form a uniform coating layer without poor appearance. In the present invention, when a uniform hard coat layer is formed on such a highly transparent support,
Particularly effective.

The hard coat layer of the present invention is formed by applying the coating composition to the surface of the above-mentioned transparent support or the like using a known coating apparatus and then irradiating it with ionizing radiation to cure it. . As a coating device, a known coating device such as a micro gravure coater, a gravure coater, a Meyer bar coater, or a die coater can be used. The viscosity and concentration of the coating composition at the time of coating can be adjusted to an appropriate value depending on the coating device used, within a range that does not impair the curing of the present invention.

From the viewpoint of antistatic property, the surface resistivity of the hard coat layer (measured according to JIS K6911, the unit is described as Ω / □ in this specification) is 5.0 × 10 ¹¹ (Ω /
Less than □), particularly preferably 1.0 × 10 ¹⁰
It is less than (Ω / □). When the hard coat film of the present invention is used for a display, the haze value (measured according to JIS K7105) of the hard coat film is 6.0.
%, Preferably 4.5%
Is less than.

[0021]

[Examples] The specific contents of the coating composition of the present invention and samples prepared using the same will be described below with reference to Examples, and the coating composition of the present invention and samples prepared using the same will be compared with Comparative Examples. Although described in comparison, the present invention is not limited thereto. In the examples, "parts" and "%" represent "parts by weight" and "% by weight" unless otherwise specified.

Example 1 On one side of a 75 μm polyester film (A-4300; manufactured by Toyobo Co., Ltd.), the coating composition shown in Table 1 below was applied with a bar coater, and a diluting solvent was applied with a dryer at 60 ° C. After evaporation, UV light was irradiated to obtain an antistatic hard coat film. The thickness of the coating layer at this time was 5 μm.

[0023]

[Table 1]

Example 2 In the formulation of the coating composition, 4-methyl-2-pentanol (dielectric constant: 9.9, boiling point: 131.
After preparing the coating material in the same manner as in Example 1 except that (8 ° C.) was used, an antistatic hard coat film was prepared. Example 3 In the same manner as in Example 1, except that 1-propanol (dielectric constant: 22.2, boiling point: 97.2 ° C.) was used as a coating preparation solvent in the formulation of the coating composition, an antistatic hard coating was prepared. A coated film was produced. Example 4 In the formulation of the coating composition, cyclohexanone (dielectric constant: 18.3, boiling point: 155.7 ° C.) was used as a coating preparation solvent.
After preparing the coating material in the same manner as in Example 1 except that the above was used, an antistatic hard coat film was prepared.

Example 5 The solid content concentration of the coating composition was set to 60.6% by weight, and Beamset 550B was used as a resin in the coating composition formulation.
85.0 parts by weight, and 50.0 parts by weight of antimony-doped SnO ₂ (30.0% content-methanol dispersion, average average particle diameter 0.095 μm) as a conductive agent (internal SnO ₂ : 1)
(5.0 parts by weight) An antistatic hard coat film was prepared in the same manner as in Example 1 except that the coating material was prepared. Example 6 The solid content concentration of the coating composition was set to 35.5% by weight, and Beamset 550B was used as a resin in the coating composition formulation.
35.0 parts by weight, and 216.7 parts by weight of SnO ₂ (containing 30.0% -methanol dispersion, average average particle size 0.095 μm) doped with antimony as a conductive agent (internal SnO ₂ :
65.0 parts by weight) An antistatic hard coat film was prepared in the same manner as in Example 1 except that the coating material was used. Example 7 The solid content concentration of the coating composition was set to 20.1% by weight, and 4-methyl was used as the coating preparation solvent in the coating composition formulation.
-2-Pentanone (dielectric constant: 13.1, boiling point: 115.9
(° C) was used in the same manner as in Example 1 except that 340.0 parts by weight was used, and then an antistatic hard coat film was produced.

Example 8 Antimony-doped ZnO (30.0% content-methanol dispersion liquid) was used as a conductive agent in the formulation of the coating composition.
Example 1 except that the average average particle diameter was 0.080 μm)
After preparing the coating material in the same manner as in (1), an antistatic hard coat film was prepared. Example 9 An antistatic hard coat film was produced after preparing a coating material in the same manner as in Example 1 except that a triacetyl cellulose film was used as the transparent plastic film.

Example 10 The solid content concentration of the coating composition was set to 65.2% by weight, and the beam set 550B was used as a resin in the coating composition.
90.0 parts by weight of antimony-doped SnO2 as conductive agent (30.0% content - methanol dispersion, mean average particle size 0.095 m) 33.3 parts by weight (inner SnO _2: 1
An antistatic hard coat film was prepared after preparing the coating material in the same manner as in Example 1 except that 0.0 parts by weight) was used. Example 11 The solid content concentration of the coating composition was set to 34.1% by weight, and Beamset 550B was used as a resin in the coating composition formulation.
30.0 parts by weight, and 233.3 parts by weight of SnO ₂ (containing 30.0% -methanol dispersion, average average particle size 0.095 μm) doped with antimony as a conductive agent (internal SnO2:
70.0 parts by weight) An antistatic hard coat film was prepared in the same manner as in Example 1 except that the coating material was used.

Comparative Example 1 After preparing a coating material in the same manner as in Example 1 except that toluene (dielectric constant: 2.2, boiling point: 111.0 ° C.) was used as a coating material preparation solvent in the formulation of the coating composition, antistatic treatment was performed. A hard coat film was produced. Comparative Example 2 An antistatic hard coat was prepared in the same manner as in Example 1 except that isobutyl acetate (dielectric constant: 5.3, boiling point: 118.0 ° C.) was used as a coating preparation solvent in the formulation of the coating composition. A film was made. Comparative Example 3 An antistatic hard coat film was prepared in the same manner as in Example 1 except that methanol (dielectric constant: 33.1, boiling point: 64.5 ° C.) was used as a coating preparation solvent in the formulation of the coating composition. Was produced.

Comparative Example 4 Methyl ethyl ketone (dielectric constant: 18.5, boiling point: 79.6 ° C.) was used as a paint preparation solvent in the formulation of the paint composition.
After preparing the coating material in the same manner as in Example 1 except that the above was used, an antistatic hard coat film was prepared. Comparative Example 5 In the formulation of the coating composition, ethylene glycol (dielectric constant: 38.7, boiling point: 197.9) was used as a coating preparation solvent.
After preparing the coating material in the same manner as in Example 1 except that (.degree. C.) was used, an antistatic hard coat film was prepared. Comparative Example 6 The solid content concentration of the coating composition was 54.6% by weight, and 4-methyl was used as the coating preparation solvent in the coating composition formulation.
-2-Pentanone (dielectric constant: 13.1, boiling point: 115.9
(° C.) Was used, and then an antistatic hard coat film was prepared in the same manner as in Example 1 except that the coating material was prepared.

The coating compositions prepared in Examples 1 to 11 and Comparative Examples 1 to 6 and the antistatic hard coat films produced from them were evaluated according to the following procedures. After preparing the pigment dispersible paint of the paint composition, put the paint into a test tube to a height of 10 cm, and
The degree of pigment sedimentation after time was evaluated. Pigment precipitation height after 5 hours / 10 cm = 0.7 or more was evaluated as ◯, and less than 0.7 was evaluated as x. Transparency of coated product Using a haze meter manufactured by Toyo Seiki Co., Ltd., the haze degree was measured according to JIS K7105.

The transparency was evaluated based on the degree of haze.
Less than 4.5%: particularly good, 4.5 or more and less than 6.0%: good, 6.0 or more and less than 7.0%: somewhat poor, 7.0% or more: particularly poor. If the haze degree is less than 7.0, there is no practical problem. Backlight light was observed through the film having a uniform appearance of the coated product to confirm the presence or absence of unevenness of the coating layer.

The uniformity was evaluated based on the presence or absence of unevenness of the coating layer. No unevenness: particularly good, almost no unevenness: good,
There is unevenness, but there is no problem in practical use: Slightly defective, unevenness: Especially bad. Antistatic property The surface resistivity (Ω / □) was measured using Hiresta-UP, a high resistivity meter manufactured by Mitsubishi Chemical Corporation. The antistatic property was evaluated based on the surface resistivity. Less than 1.0 × 10 ¹⁰ (Ω / □):
Particularly good, 1.0 × 10 ¹⁰ or more 5.0 × 10 ¹¹ (Ω
Less than / □): Good, 5.0 × 10 ¹¹ or more, 1.0 × 10
Less than ¹³ (Ω / □): Slightly defective, 1.0 × 10 ¹³ (Ω
/ □) or more: particularly bad Surface resistivity is 1.0 × 1
If it is less than 0 ¹³ (Ω / □), there is no practical problem. Using pencil hardness HEIDON14, the pencil hardness was measured according to JIS K5400. Hardness was evaluated based on the pencil hardness. Two
H: Particularly good, H: good, HB: bad. If the pencil hardness is H or higher, there is no practical problem.

[0033]

[Table 2]

From Table 2 (evaluation results) above, Examples 1 to 1
In No. 1, by incorporating 30.0 parts by weight or more of a solvent having a dielectric constant of 9.0 or more and a boiling point of 90 ° C. or more and less than 180 ° C. as a solvent in the coating material, antistatic property, transparency, uniformity, resistance to An antistatic hard coat film excellent in scratch resistance and chemical resistance could be obtained. On the other hand, Comparative Example 1 in which the boiling point and the dielectric constant of the solvent in the paint do not satisfy the above conditions
In the hard coat films obtained in Nos. 6 to 6, the qualities such as antistatic property, transparency, uniformity and scratch resistance could not be satisfied.

Although not practically problematic, the antistatic hard coat film obtained in Example 10 was
Since the blending ratio of the ultrafine metal oxide particles in the solid content of the coating material for the hard coat layer was 10% by weight, the antistatic property was slightly inferior. Further, the antistatic hard coat film obtained in Example 11 contained 70.0% by weight of the metal oxide ultrafine particles, and thus the transparency of the coating layer was slightly inferior. Furthermore, in Example 10 in which the solid content concentration is 65.2% by weight, the uniformity of the appearance of the obtained antistatic hard coat film was slightly inferior.

[0036]

EFFECT OF THE INVENTION Ultrafine metal oxide particles are blended in the coating composition of the present invention, and a solvent having a dielectric constant of 9.0 or more and a boiling point of 90 ° C. or more and less than 180 ° C. is used as a solvent for preparing the coating composition. By blending 0 parts by weight or more, a hard coat layer having excellent antistatic properties, transparency, uniformity, scratch resistance, and chemical resistance can be uniformly formed on a transparent plastic film, thereby significantly improving productivity. can get.

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Claims (6)

[Claims] 1. An ionizing radiation curable resin, ultrafine metal oxide particles having an average particle diameter of 0.3 μm or less, and a dielectric constant of 9.
00.0 or more and a boiling point of 90 ° C. or more and less than 180 ° C., and 30.0 parts by weight of the solvent with respect to a total of 100.0 parts by weight of the ionizing radiation curable resin and the metal oxide ultrafine particles. A coating composition blended as described above. 2. The coating composition according to claim 1, wherein the ultrafine metal oxide particles are tin oxide (SnO ₂ ) doped with antimony. 3. The coating composition according to claim 1, wherein the ultrafine metal oxide particles are antimony-doped zinc oxide (ZnO). 4. The coating composition according to claim 1, wherein the content of ultrafine metal oxide particles in the solid content of the coating composition is 15.0% by weight or more and less than 70.0% by weight. Composition. 5. An antistatic hard coat film having a hard coat layer obtained by applying the coating composition according to any one of claims 1 to 4 on a film support. 6. The antistatic hard coat film according to claim 5, wherein the film support is a triacetyl cellulose film.