JPH0676357A - Ultraviolet-curing resin composition for coating optical disk - Google Patents

Abstract

PURPOSE:To improve the initial antistatic performance of a coating film, the adhesion of the film to the substrate and the hardness of the film by using a UV-curing resin compsn. contg. 30-70wt.% (meth) acrylic ester having carboxyl groups. CONSTITUTION:This UV-curing resin compsn. contains 30-70wt.% (meth)-acrylic ester having carboxyl groups such as acrylate dimer, methacrylate dimer or ethylene oxide modified succinoacrylate. This compsn. preferably contains an org. compd. having two or more active ethylene groups in each molecule besides the (meth)acrylic ester so as to improve the hardness of a formed coating film.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an ultraviolet-curable resin composition for coating an optical disk.

[0002]

2. Description of the Related Art Polycarbonate, polymethylmethacrylate, etc. are generally used for optical disk substrates, which are attracting attention as next-generation recording media, but the surface hardness of these substrates themselves is small. Therefore, it has been proposed to coat the surface with a resin composition such as an ultraviolet curable resin in order to prevent the surface from being scratched during handling.

The resin composition for coating the surface of the optical disk preferably has a high hardness in order to prevent scratches during handling, but other than that, errors in recording and reading operations due to adhesion of dust in the air. In order to prevent this, it is desired to have antistatic performance.

[0004]

As a method for obtaining such an antistatic property, for example, a method of applying an antistatic agent such as a surfactant to the surface is known. Preventive performance is good, but surface cleaning,
Due to abrasion, the antistatic agent component is easily dropped off, resulting in deterioration of performance in a short period of time.

Therefore, a method of coating the disk surface with an ultraviolet curable resin composition in which an antistatic agent is kneaded has been studied. In the case of such a composition, the antistatic effect is exhibited by the antistatic agent bleeding on the resin surface. However, in the case of the ultraviolet curable resin composition, a three-dimensionally crosslinked structure is obtained after curing, so that it is kneaded. It is difficult for the antistatic agent to migrate to the surface. Even with this method, it is inevitable that the antistatic agent bleeding on the surface will fall off due to cleaning, abrasion, etc., and long-term stability of the antistatic performance of the optical disk substrate surface has not been achieved.

The problem to be solved by the present invention is to provide a UV-curable resin composition for optical disk coating, which has a high initial antistatic property and is capable of forming a cured film of an optical disk whose performance is not easily deteriorated by washing or the like. To provide things.

[0007]

In order to solve the above-mentioned problems, the present invention contains 30 to 70% by weight of a (meth) acrylic acid ester having a carboxyl group, which is a UV-curable resin for coating an optical disk. A composition is provided.

The present invention will be described in detail below.

Examples of the (meth) acrylic acid ester having a carboxyl group used in the present invention include acrylic acid dimer, methacrylic acid dimer, ethylene oxide-modified succinic acid acrylate, ethylene oxide-modified succinic acid methacrylate, ethylene oxide-modified phthalic acid acrylate, and ethylene oxide. Examples thereof include modified phthalic acid methacrylate and ω-carboxy-polycaprolactone monoacrylate.

The proportion of these compounds in the ultraviolet curable resin composition is preferably 30 to 70% by weight.
If it is less than 30% by weight, the antistatic performance is inferior.
%, The coating hardness tends to decrease, which is not preferable.

An ultraviolet-curable resin composition containing 5 to 15% by weight of a (meth) acrylic acid ester having a carboxyl group is described in JP-A-2-123172, and an optical disk coated with the composition is also disclosed. It is described in the publication. However, in the specification, the (meth) acrylic acid ester having a carboxyl group in the molecule is added for the purpose of improving the adhesiveness to the substrate, and the antistatic performance targeted in the present invention is , Which is not described in the specification at all, and from the ultraviolet curable resin composition in the range described in the specification, as is clear from Comparative Examples described below, a cured film having satisfactory antistatic performance. I can't get it.

In addition to the above-mentioned compounds, the ultraviolet-curable resin composition of the present invention preferably contains an organic compound containing at least two or more active ethylene groups in the molecule in order to improve the film hardness. . Examples of such compounds include poly (ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, trimethylolpropane, glycerin, pentaerythritol, and the like). (Meth) acrylate;
Di (meth) acrylate of diol obtained by adding 2 moles or more of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol; obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane Diol or tri (meth) acrylate of triol; bisphenol A1
Di (meth) acrylate of diol obtained by adding 2 moles or more of ethylene oxide or propylene oxide to moles; poly (meth) acrylate of dipentaerythritol, acryloxyethyl isocyanurate, styrene, etc. But itself
Polymerization is performed in the presence of a photopolymerization initiator, and the coating film hardness in that case is 3H or more in terms of pencil hardness. The proportion of the organic compound containing at least two or more active ethylene groups in these molecules in the composition is not particularly limited.

In the above mixture, a photopolymerization initiator is used in an amount corresponding to the ultraviolet irradiation conditions. The photopolymerization initiator may be any one usually conceivable, for example, 2-hydroxy-2-methyl-1-phenylpropan-1-one (“Darocur 1173” manufactured by Merck & Co., Inc.), 1-hydroxycyclohexylphenylketone. (“Irgacure 184” manufactured by Ciba Geigy), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1-
On (Merck "Darocur 1116"), benzyl dimethyl ketal (Ciba Geigy "Irgacure 651"), 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1 (Ciba)・ Geigy's "Irgacure 907"), 2,4-diethylthioxanthone (Nippon Kayaku's "Kayacure DET"
X ”) and ethyl p-dimethylaminobenzoate (“ Kayacure-EPA ”manufactured by Nippon Kayaku Co., Ltd.), isopropylthioxanthone (“ Cantacure ITX ”manufactured by Ward Prekinsop) and ethyl p-dimethylaminobenzoate. And the like. The amount used is determined by the conditions of the ultraviolet irradiator used for curing, but it is generally preferable to use 3 to 7% by weight based on the weight of the resin mixture.

A polymerization inhibitor, an antifoaming agent, a leveling agent, a solvent, a polymerizable diluent and the like may be added to the above composition. In addition, the above composition is usually applied to the laser light incident side of an optical disc.

The surface resistance of the film after curing the composition of the present invention by ultraviolet irradiation is preferably 1.0 × 10 ¹⁴ Ω / □ or less under the conditions of 25 ° C. and 50% RH.
If it exceeds 1.0 × 10 ¹⁴ Ω / □, the antistatic performance tends to be poor, and the effect of preventing the adhesion of dust on the coated surface tends to decrease, which is not preferable. .

Further, the hardness of the film is a pencil hardness of F or more when measured according to JIS K-5400,
It is preferable for preventing scratches on the substrate surface.

[0017]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the examples, "part" means "part by weight". The surface resistance is in accordance with JIS K-6911.
It was measured in an environment of 25 ° C. and 50% RH. Pencil hardness is JIS K-5400, adhesion is JIS K-5
It was measured by a cross-cut / cellophane tape peeling test according to 400. Further, in order to evaluate the cleaning resistance, a pure water immersion test was conducted by immersing the coated substrate in pure water for 24 hours.

Example 1 Ethylene oxide-modified succinic acid acrylate (“Aronix M-5500” manufactured by Toagosei Kagaku Kogyo Co., Ltd.) as a carboxyl group-containing raw material, and 1,6-hexanediol diacrylate (Japan) as an active ethylene-containing compound. Kayarad HDDA manufactured by Kayaku Co., Ltd.)
And pentaerythritol tetraacrylate (“PE-4A” manufactured by Kyoeisha Oil and Fat Chemical Co., Ltd.) 60 and 2, respectively.
2 and 13 parts were mixed. A resin composition was prepared by mixing 5 parts of "Darocurure 1173" manufactured by Merck Ltd. as a photopolymerization initiator with the composition.

This composition was coated on a polycarbonate substrate for an optical disk with a spin coater and then 410 mW / c
Irradiation with a metal halide lamp of m ² for 5 seconds gave a substrate having a cured film. A dielectric band layer, a recording film layer, and a reflective film layer were sequentially formed on the surface of the substrate opposite to the film by a sputtering method, and further overcoated to obtain an optical disk of the present invention. The results of measuring the physical properties of this disk are shown in Table 1.

Example 2 Example 2 was repeated except that ethylene oxide-modified succinic acid methacrylate was replaced with ethylene oxide-modified succinic acid methacrylate (“Light Ester HO-MS” manufactured by Kyoeisha Oil and Fat Chemical Co., Ltd.). An optical disc was obtained in the same manner as in Example 1. The results of measuring the physical properties of this disk are shown in Table 1.

Example 3 An acrylic acid dimer (“M-5600” manufactured by Toa Synthetic Chemical Industry Co., Ltd.) was used in place of the ethylene oxide-modified succinic acid acrylate in Example 1.
An optical disc was obtained in the same manner as in Example 1 except that The results of measuring the physical properties of this disk are shown in Table 1.

[0022]

[Table 1]

(Examples 4 and 5, Comparative Examples 1 and 2) Example 1
In, the amount of ethylene oxide modified succinic acid acrylate used was 30 parts (Example 4), 90 parts (Example 5),
An optical disc was prepared in the same manner as in Example 1 except that the amount was changed to 7 parts (Comparative Example 1) and 120 parts (Comparative Example 2). The results of measuring the physical properties of this disk are shown in Table 2.

[0024]

[Table 2]

[0025]

As described above, according to the present invention, a cured film having a high initial antistatic property, excellent adhesion to a substrate and film hardness, and having no deterioration in antistatic property even by washing is provided. It became possible to obtain an optical disc.

Claims (2)

[Claims] 1. An ultraviolet-curable resin composition for coating an optical disk, comprising 30 to 70% by weight of a (meth) acrylic acid ester having a carboxyl group. 2. An optical disk having a cured film made of the ultraviolet-curable resin composition for optical disk coating according to claim 1.