JP2003262703A - Transparent base material having hardened film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material having sufficient antireflection performance with only a single layer of an antireflection film. <P>SOLUTION: A hardened film made of a composition comprising a compound having at least two (meth)acryloyloxy groups in a molecule or its oligomers and porous fine particles is formed on the surface of the transparent base material. As for the porous fine particles, silica fine particles are preferable, or surface-coated silica having a double structure or a compound oxide containing silica is also effective. By forming the hardened film with 1.20 to 1.45 refractive index and 0.01 to 1 μm film thickness, the film functions as an antireflection film. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent base material having a cured coating film formed on its surface.

[0002]

2. Description of the Related Art Conventionally, a functional coating film such as an antireflection film has been formed and used on the surface of a transparent substrate such as glass or resin for a display. In particular, from the viewpoint of cost, many base materials having a coating film obtained by applying an antireflection material as a paint, rather than the vapor deposition method or the sputtering method, have been developed. For example, JP-A-8-100136 discloses that a copolymer of vinylidene fluoride and hexafluoropropylene is blended with a polymerizable compound having an ethylenically unsaturated group, and is used for forming an antireflection film. A system paint is described.

However, the conventionally used antireflection film has an insufficient antireflection performance. For example, the one described in JP-A-8-100136 mentioned above has a refractive index of 1.4.
It was about 3, and sufficient antireflection performance was not obtained.
Further, in order to improve the antireflection performance, it is preferable that the antireflection layer has a two-layer structure composed of a high refractive index layer and a low refractive index layer.
As disclosed in Japanese Patent Laid-Open No. 2001-315242, in this case, the reflectance is reduced to 100 to 20 around a specific wavelength.
There is a problem that the reflected light is strongly colored due to interference because it is only in the wavelength range of 0 nm and the reflectance is high at other wavelengths.

[0004]

Therefore, the present inventor has conducted diligent research to develop a material having a sufficient antireflection property with a single-layer antireflection film, and as a result, a specific composition was cured. The present invention has been completed by finding that the coating film obtained in this manner exhibits sufficient antireflection performance.

[0005]

Means for Solving the Problems That is, the present invention provides a method for curing a composition containing a compound having at least two (meth) acryloyloxy groups in the molecule or an oligomer thereof on the surface of a substrate and porous fine particles. The present invention provides a transparent substrate having a film formed thereon.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the transparent substrate of the present invention, a cured coating is formed on the surface, and the cured coating has a curable compound having at least two (meth) acryloyloxy groups in the molecule or a compound thereof. Porous silica fine particles are dispersed in a cured product of an oligomer (hereinafter sometimes referred to as a polyfunctional (meth) acryloyloxy compound). This cured coating forms the antireflection layer. This cured coating film can be obtained by forming a coating film made of a composition in which porous fine particles are dispersed in a polyfunctional (meth) acryloyloxy compound on a substrate and curing the coating film.

In the present invention, a polyfunctional (meth) acryloyloxy compound is used as the curable compound. This compound is a compound having at least two (meth) acryloyloxy groups in the molecule or an oligomer thereof. Here, the (meth) acryloyloxy group refers to an acryloyloxy group or a methacryloyloxy group, and the term "(meth)" when referring to (meth) acrylate or (meth) acrylic acid in the present specification is also the same. Is the meaning of.

Examples of the polyfunctional (meth) acryloyloxy compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate. Acrylate,
Trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, glycerin tri (meth) acrylate, pentaglycerol tri (meth) acrylate, pentaerythritol tri-
Or poly (meth) acrylic acid of a polyhydric alcohol such as tetra- (meth) acrylate, dipentaerythritol tri-, tetra-, penta- or hexa- (meth) acrylate, tris (meth) acryloyloxyethyl isocyanurate Ester; phosphazene (meth) acrylate compound in which (meth) acryloyloxy group is introduced into phosphazene ring of cyclic phosphazene compound; polyisocyanate compound having at least two isocyanato groups in molecule, A urethane (meth) acrylate compound obtained by reacting a (meth) acrylic acid esterified compound; a carboxylic acid halide having at least two carbonyl groups in the molecule, and a part of hydroxyl groups of the polyol (meta). ) Acrylic acid S Reacting the Le of compounds and polyester (meth) acrylate compound obtained. These compounds may be used alone or in combination of two or more. Also,
An oligomer in which each of these compounds is a dimer, a trimer or the like may be used.

Since some polyfunctional (meth) acryloyloxy compounds are commercially available, they can also be used. Examples of such commercially available products include "NK Ester A-TMM-3L" (Pentaerythritol triacrylate manufactured by Shin-Nakamura Chemical Co., Ltd.) and "NK Ester A-
-9530 "(Shin-Nakamura Chemical Co., Ltd., dipentaerythritol hexaacrylate)," KAYARAD DPCA "(Nippon Kayaku Co., Ltd., dipentaerythritol hexaacrylate)," Aronix M-8560 "(Toagosei ( stock)
Polyester acrylate compound), "New Frontier TEICA" (Daiichi Kogyo Seiyaku Co., Ltd., trisacryloyloxyethyl isocyanurate), "PPZ" (Kyoeisha Chemical Co., Ltd., phosphazene methacrylate compound) are exemplified. It It is also possible to use a commercially available product mixed with a solvent. Examples of such a solvent-mixed commercial product include “Aronix UV370
1 "(manufactured by Toagosei Co., Ltd.)," Unidick 17-813 "
(Manufactured by Dainippon Ink and Chemicals, Inc.), "NK Hard M-10
1 ”(manufactured by Shin-Nakamura Chemical Co., Ltd.) and the like.

The porous fine particles are not particularly limited, but those having an average particle size in the range of 5 nm to 10 μm are preferably used. In particular, when forming a film as an antireflection film, fine particles having an average particle size in the range of 5 nm to 100 nm are more preferable. If the particle size is too small, it is difficult to industrially manufacture, and if the particle size becomes too large,
It is not preferable because the optical performance such as the transparency of the coating is deteriorated.

As the porous fine particles, silica fine particles are preferable because the material itself has a low refractive index and strength. Porous silica has a refractive index of about 1.2 to 1.4, which is lower than the refractive index of ordinary silica fine particles of 1.46, and is preferable for forming an antireflection material. The porous silica, for example, as shown in JP-A-7-48527, obtained by hydrolyzing an alkoxysilane in the presence of an alkali, highly entangled and branched, silica produced in the form of a polymer Is mentioned.

As the porous fine particles, it is also possible to use silica or a complex oxide containing silica having a double structure with the surface coated. Such a surface-coated silica having a double structure or a composite oxide containing silica,
For example, it can be produced by the method described in JP-A-7-133105. In particular, porous silica fine particles whose surface is coated to have a double structure are preferably used because the pore inlets of the particles are closed and the porosity inside the particles is maintained.

The amount of the porous fine particles is not particularly limited,
It is usually in the range of 10 to 90% by weight based on the total amount of the polyfunctional (meth) acryloyloxy compound and the porous fine particles. If the amount of the porous fine particles is too small, the refractive index of the coating may not be lowered and sufficient antireflection performance may not be obtained, and if the amount is too large, the strength of the film may be reduced. When a film is formed as an antireflection film, the amount of porous fine particles added is selected so that the refractive index of the film is preferably 1.20 to 1.45, more preferably 1.25 to 1.41. Is preferred. The addition amount at that time varies depending on the refractive index of the porous fine particles, but is usually within the range described above, and more preferably 15 to 70% by weight.

The substrate used in the present invention is not particularly limited as long as it is transparent, but for example, polymethylmethacrylate resin, polycarbonate resin, polystyrene, methylmethacrylate-styrene copolymer resin, acrylonitrile-styrene copolymer resin. Resin base materials such as triacetyl cellulose resin, and inorganic base materials such as inorganic glass. In particular, methyl methacrylate-
The styrene copolymer has a small expansion and contraction due to moisture absorption and is suitable as a base material of an antireflection plate.

The substrate may have a flat surface such as a plate (sheet) or a film, or may have a curved surface such as a convex lens or a concave lens. . In addition, fine irregularities may be provided on the surface. In the case of a resin base material, another coating such as a hard coat layer may be formed on the surface thereof.

In order to apply a composition containing a polyfunctional (meth) acryloyloxy compound and porous fine particles onto a substrate, it is necessary to form a coating composition containing each of these components. The paint usually contains a polyfunctional (meth) acryloyloxy compound and porous fine particles, a polymerization initiator, a solvent, and if necessary, various additives.

The polymerization initiator is necessary for forming a cured film. Since the polyfunctional (meth) acryloyloxy compound is a radical-polymerizable compound, a polymerization initiator that generates radicals by irradiation with ultraviolet rays is preferably used. As such a polymerization initiator, benzyl, benzophenone and its derivatives, thioxanthones, benzyl dimethyl ketals, α-hydroxyalkylphenones, hydroxyketones, aminoalkylphenones,
Acylphosphine oxides are preferably used.

These polymerization initiators can be used alone or in a mixture of two or more kinds. Further, since these various polymerization initiators are commercially available, such commercially available products can be used. Examples of commercially available polymerization initiators include “IRGACURE 651”, “IRUGACURE 184”, and “IRUGACURE” sold by Ciba Specialty Chemicals Co., Ltd.
907 ”,“ IRUGACURE500 ”,“ DAROCURE 1173 ”, etc.
"KAYACURE BP-10" sold by Nippon Kayaku Co., Ltd.
0 ”,“ KAYACURE DETX-S ”,“ HICURE OBM ”sold by Kawaguchi Pharmaceutical Co., Ltd.,“ QUANTACURE ITX ”sold by Shell Chemical Co., Ltd., B
"LUCIRIN TPO" sold by ASF, "ESACUR" sold by Japan Siber Hegner Co., Ltd.
E EB3 ”and the like.

The polymerization initiator is usually used in an amount of 0.1 to 2 per 100 parts by weight of the polyfunctional (meth) acryloyloxy compound.
It is added in an amount of 0 parts by weight, preferably 0.5 to 10 parts by weight. If the amount of the initiator is too small, the UV polymerization property of the polyfunctional (meth) acryloyloxy compound will not be sufficiently exhibited, and even if the amount is too large, the effect of increasing the amount will not be recognized, which is economically disadvantageous. In addition, there is a possibility that the optical characteristics of the coating may be deteriorated, which is not preferable.

The solvent is used to adjust the concentration and viscosity of the coating material, the film thickness after curing, and the like. The solvent used may be appropriately selected, for example, methanol, ethanol,
Propanol, isopropanol, n-butanol, 2
-Alcohols such as butanol, isobutanol, tert-butanol, alkoxy alcohols such as 2-ethoxyethanol, 2-butoxyethanol, 3-methoxypropanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol , Ketols such as diacetone alcohol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, etc. .
The amount of the solvent used is appropriately selected according to the material of the substrate, the shape, the coating method, the film thickness of the target coating, etc., but usually the polyfunctional (meth) acryloyloxy compound and the porous silica fine particles are used. 20 to 100 per 100 parts by weight in total
It is in the range of about 00 parts by weight.

Further, the coating material may contain additives such as a stabilizer, an antioxidant, a coloring agent and a leveling agent. In particular, silicone oil is effective in improving not only the leveling property but also the slip property of the surface of the cured film and the surface hardness, and therefore it is preferably added.

As the silicone oil, usual ones can be used, and specifically, dimethyl silicone oil, phenylmethyl silicone oil, alkyl / aralkyl modified silicone oil, fluorosilicone oil, polyether modified silicone oil, fatty acid ester modified silicone. Oil, methyl hydrogen silicone oil, silanol group-containing silicone oil, alkoxy group-containing silicone oil, phenol group-containing silicone oil, methacryl-modified silicone oil, amino-modified silicone oil, carboxylic acid-modified silicone oil, carbinol-modified silicone oil, epoxy-modified silicone Examples thereof include oil, mercapto-modified silicone oil, fluorine-modified silicone oil, and polyether-modified silicone oil. These silicone oils may be used alone or in combination of two or more. The amount of silicone oil added is usually about 0 to 20 parts by weight based on 100 parts by weight of the total of the polyfunctional (meth) acryloyloxy compound and the porous fine particles. If the amount is more than 20 parts by weight, the optical performance and the film strength are deteriorated, which is not preferable.

By applying the coating material as described above to the surface of the base material, a coating film comprising a polyfunctional (meth) acryloyloxy compound and porous fine particles is formed. To apply the paint to the surface of the substrate, the same methods as usual, for example, microgravure coating method, roll coating method, dipping coating method, flow coating method, spin coating method, die coating method, cast transfer method, spray coating It may be applied by a method such as a method.

Then, this coating is irradiated with ultraviolet rays. The irradiation time of ultraviolet rays is not particularly limited, but usually 0.1 to
The range is about 60 seconds. UV light is usually 10-40 ℃
Irradiation can be performed in a moderate atmosphere. The irradiation energy of ultraviolet rays to be irradiated is usually about 50 to 3,000 mJ / cm ² . If the irradiation amount of ultraviolet rays is too small, curing will be insufficient and the strength of the film will decrease. On the other hand, if the irradiation amount of ultraviolet rays is too large, the coating film or the base material may be deteriorated and the optical characteristics and mechanical properties may be deteriorated, which is not preferable.

When the coating material contains a solvent, the ultraviolet rays may be irradiated with the coating film still containing the solvent, or after the solvent is volatilized. When the solvent is volatilized, it may be left at room temperature or may be dried by heating at about 30 to 100 ° C. The drying time is appropriately selected according to the material and shape of the base material, the coating method, the desired film thickness of the coating film, and the like. After forming the cured coating by ultraviolet irradiation, heat treatment may be further performed to make the cured coating stronger. The heating temperature and time are appropriately selected, but are usually about 50 minutes to 120 ° C. and about 30 minutes to 24 hours.

The cured film formed usually has a thickness of 0.0.
It is preferable that the thickness is in the range of 1 to 1 μm. If the film thickness is less than 0.01 μm or more than 1 μm, the function as an antireflection film is likely to deteriorate.

[0027]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. In the examples,% and parts indicating the content or the amount used are based on weight unless otherwise specified. The reflectance of the base material obtained in each example was evaluated by the following method.

[Method of Measuring Reflectance] The surface of the base material opposite to the measurement surface side is roughened with steel wool, coated with black paint and dried, and then absolute specular reflection at an incident angle of 5 ° on the measurement surface. Spectra for UV-Visible Spectrophotometer ["UV-3
100 ", manufactured by Shimadzu Corporation], and the wavelength at which the reflectance is minimum and the minimum value of the reflectance were obtained.

Example 1 100 parts of a sol in which 20% of porous silica fine particles having a particle size of 20 to 70 nm and whose surface was coated with a hydrolyzate of ethyl silicate were dispersed in isopropyl alcohol, and 20 parts of dipentaerythritol hexaacrylate were used. Part, photoinitiator “IRGACURE 907” [obtained from Ciba Specialty Chemicals Co., Ltd., chemical name is 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-
On] 1 part, isopropyl alcohol 1,679
And 200 parts of 2-butoxyethanol were mixed and dispersed to obtain a coating material.

A methylmethacrylate-styrene copolymer resin plate [“Acryace MS” manufactured by Nippon Acreace Co., Ltd.] containing about 40% of styrene units was dipped in this coating material and dip-coated at a pulling speed of 24 cm / min. Then, it was dried at room temperature for 1 minute or more and then at 60 ° C. for 10 minutes.
After drying, a high-pressure mercury lamp ["UVC-35" made by Ushio Inc.
33 ″] was irradiated with ultraviolet rays at an energy of about 1,000 mJ / cm ² to obtain a transparent base material having antireflection performance. The evaluation results of this transparent base material are shown in Table 1. Calculating the refractive index of the coating from the reflection spectrum 1.
395, and the film thickness similarly calculated from the reflection spectrum was 104 nm. This base material was less colored by the reflected light due to the interference color.

Example 2 A transparent substrate having antireflection performance was produced in the same manner as in Example 1 except that the composition of the coating material was changed as follows.

[0032] 120 parts of 20% sol of the same porous silica fine particles as in Example 1 Dipentaerythritol hexaacrylate 16 parts Photoinitiator "IRGACURE 907" 1 part Isopropyl alcohol 1,663 parts 2-Butoxyethanol 200 parts

Table 1 shows the evaluation results of the obtained transparent substrate. With respect to the coating film of this base material, the refractive index calculated from the reflection spectrum was 1.37, and the film thickness calculated from the reflection spectrum was 100 nm. This substrate was also less colored by the reflected light due to the interference color.

Comparative Example 1 40 parts of dipentaerythritol hexaacrylate,
2 parts of photoinitiator "IRGACURE907", 1,758 parts of isopropyl alcohol, and 2 parts of 2-butoxyethanol.
00 parts were mixed and dispersed to obtain a paint. Using this paint, a transparent base material having antireflection performance was produced in the same manner as in Example 1. The evaluation results of this transparent substrate are shown in Table 1. When the reflection spectrum of the coating film of this substrate was measured, almost no antireflection performance was observed.

Comparative Example 2 A sol in which silica particles were dispersed in isopropyl alcohol at a concentration of 20% (“IPA-ST” manufactured by Nissan Chemical Industries, Ltd.) was used in place of the sol of porous silica particles. A transparent base material having antireflection performance was obtained in the same manner as in Example 2. With respect to the coating film of this substrate, the refractive index calculated from the reflection spectrum was 1.47, and the film thickness similarly calculated from the reflection spectrum was 102 nm.

[0036]

[Table 1]

[0037]

The transparent substrate having the cured coating of the present invention is
Since it has excellent antireflection performance and little coloring due to interference of reflected light, it is useful as a protective plate for displays and the like.

Continued front page    F-term (reference) 2K009 AA04 BB02 BB13 BB28 CC09                       CC26 CC42 DD02 DD05 DD06                 4F100 AA20B AA20H AA33B AA33H                       AK25B AL05B AT00A CC00                       DE10B EH46 EH462 EJ54                       EJ542 EJ82 EJ822 GB41                       JB12B JM02B JN01 JN06B                       JN18B YY00B                 4J038 FA111 FA211 FA231 FA261                       FA281 GA01 HA446 KA15                       KA20 KA22 NA01 NA18 NA19

Claims (4)

[Claims] 1. A cured coating formed from a composition containing a compound having at least two (meth) acryloyloxy groups in the molecule or an oligomer thereof and porous fine particles on the surface of a substrate. And a transparent substrate. 2. The transparent substrate according to claim 1, wherein the porous fine particles are silica fine particles. 3. The transparent substrate according to claim 1, wherein the porous fine particles are silica or a composite oxide containing silica having a double structure whose surface is coated. 4. The cured film as claimed in claim 1, which has a refractive index of 1.20 to 1.45 and a film thickness of 0.01 to 1 μm and has an antireflection function. Transparent substrate.