JP2888460B2 - Optical disk coating agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium cured by an ultraviolet ray which is useful as a protective coating agent for an optical disk recording medium for recording and reproducing an optical signal at high speed and high density and a hard coating agent for preventing an optical disk from being damaged. The present invention relates to a coating agent for an ultraviolet-curable optical disk having good adhesiveness and moisture resistance to UV rays.

[0002]

2. Description of the Related Art A magneto-optical recording medium utilizes perpendicular magnetic recording and a magneto-optical effect, and uses a laser beam to record and reproduce information as in a conventional optical recording medium. Rewriting is possible. Further, recording and reproduction can be performed without contact between the head and the medium, and the recording medium is not affected by dust, so that the stability is excellent. This magneto-optical recording medium is being actively studied at present, and includes a document information file,
It is expected to be used for video still image files and computer memories or to replace floppy disks and hard disks.

The recording layer of such a magneto-optical recording medium includes a transition metal (Fe, Co) and a rare earth metal (Gd, D).
y, Tb, etc.) have been proposed. As the medium configuration, a single-plate type in which a dielectric layer, a recording layer, and a dielectric layer are provided on a substrate, or a set of structures similar to the single-plate type is prepared, and the recording layer is formed on the inner side. In general, a laminating type in which an adhesive is bonded to an opposite side of the substrate.

On the other hand, the occurrence of cracks in the laminated inorganic layers on the substrate is prevented, the intrusion of oxygen and moisture into the recording layer is more completely prevented, and the magneto-optical characteristics are maintained for a long time even in a high-temperature and high-humidity environment. A cured product of an acrylate-based resin composition or a cured product of an epoxy-based resin composition used for an organic protective layer on a dielectric layer for the purpose of, for example,
JP-A-61-123593, JP-A-61-13306
7, JP-A-61-139961, JP-A-61-1538
44, JP-A-2-107630, JP-A-2-13266
No. 4 and the like.

[0005]

However, the above-mentioned conventional optical recording medium is provided with a protective layer made of a cured product of the ultraviolet-curable acrylate resin composition, thereby protecting the optical recording medium against external scratches and stains. Is achieved, but the optical recording medium is subjected to an environmental durability test (70
(90 ° C., 90% RH, 2000 hours), there is a problem that the pitting deterioration of the magneto-optical recording layer may increase or the protective layer may peel off from the disk substrate. When a protective layer made of a cured product of an epoxy resin composition is provided, pitting corrosion of the magneto-optical recording layer is less likely to occur, but reverse warpage of the disk occurs.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and uses a coating agent for an ultraviolet-curable optical disk containing a specific diacrylate compound as a protective layer. This provides an optical recording medium that can prevent scratches and dirt from the outside, has very little pitting deterioration of the magneto-optical recording layer, has no reverse warpage, and can maintain long-term reliability. Things.

That is, the present invention provides: Equation (1)

[0008]

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(Wherein, n is an integer of 9 to 20).
It is characterized by containing an unsaturated group-containing compound (B) other than styrene and / or α-methylstyrene (B) and a photopolymerization initiator (C) other than the component (A) in an amount of 100 to 600 parts by weight per 0 parts by weight. The present invention relates to a UV curable optical disc coating agent.

The diacrylate compound (A) represented by the formula (1) used in the present invention includes, for example,

[0011]

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[0012]

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[0013]

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[0014]

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[0015]

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And the like.

The unsaturated group-containing compound (B) other than the component (A) used in the present invention is specifically, for example, isobornyl (meth) acrylate, tetrahydrofuracryl (meth) acrylate, hydrogenated dicyclopentadiene ( (Meth) acrylate (manufactured by Hitachi Chemical Co., Ltd., FA-51)
3A, FA-513M), tricyclodecane dimethylol di (meth) acrylate, neopentyl glycol diacrylate hydroxypivalate, trimethylolpropane tri (meth) acrylate, pentaerythritol triacrylate, ditrimethylolpropane tetra (meth) acrylate, Dipentaerythritol penta and hexa (meth) acrylate, acryloylmorpholine, N-vinylcaprolactam, N-vinylpyrrolidone, (meth) acrylate of phenylglycidyl ether, epoxy (meth) acrylate (for example, bisphenol-type epoxy resin (Reacted product with (meth) acrylic acid, etc.), urethane (meth) acrylate (for example,
Diol compounds such as polytetramethylene glycol and ethylene glycol, diisocyanate compounds such as isophorone diisocyanate, and 2-hydroxyethyl (meth)
Reaction products with a (meth) acrylate compound having one hydroxyl group in the molecule such as acrylate).

The amount of the unsaturated group-containing compound (B) used in the coating agent for an optical disk of the present invention is 100 to 600 parts by weight based on 100 parts by weight of the diacrylate compound (A) represented by the formula (1). Parts by weight.

Photopolymerization initiator (C) used in the present invention
Any known photopolymerization initiator can be used. Specifically, for example, benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether and its alkyl ethers; acetophenone, 2,2-dimethoxy-2
-Phenylacetophenone, 2,2-diethoxy-2-
Acetophenones such as phenylacetophenone and 1,1-dichloroacetophenone; anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone and 1-chloroanthraquinone; thioxanthones such as 2,4-diethylthioxanthone, 2-chlorothioxanthone and diisopropylthioxanthone And benzyl dimethyl ketal, 2-hydroxycyclohexyl phenyl ketone, benzophenone and the like. This photopolymerization initiator (C) can be used in combination with one or more known and commonly used photopolymerization accelerators such as benzoic acid or tertiary amine, if necessary. The preferred range of the amount of the photopolymerization initiator (C) used is 0.5 to 20% by weight, particularly preferably 3 to 20% by weight, of the coating agent for an optical disk of the present invention.
-10% by weight.

The coating agent for an optical disk of the present invention comprises:
The components (A), (B) and (C) alone are sufficient to achieve the intended purpose, but as long as the original properties are not changed, leveling agents, silane coupling agents, polymerization inhibitors, antioxidants , Light stabilizers, solvents, non-basic fillers (eg, silica, talc, aluminum, silver, zinc oxide, etc.) and the like. The optical disk coating agent of the present invention can be obtained by uniformly mixing and dissolving each component.

The cured product of the coating agent for an optical disk of the present invention can be obtained by irradiating ultraviolet rays by a conventional method. Specifically, for example, it can be obtained by irradiating ultraviolet rays using a low-pressure or high-pressure mercury lamp, a xenon lamp, or the like. The coating agent for optical disks of the present invention is particularly useful as a protective coating agent for optical disk recording media, but can also be used as a hard coating agent for preventing scratches on optical disks, a groove material for optical disks, and the like.

A protective film for a recording film of an optical disk (the material used for the substrate is a plastic such as polycarbonate, polyolefin, polyepoxy, polymethyl methacrylate, glass or the like) using the coating agent for an optical disk of the present invention. The protective film is formed by applying a coating agent for an optical disk on the recording film of the optical disk by, for example, a spin coating method and irradiating ultraviolet rays to cure the coating. When a coating agent for an optical disk is applied on a recording film of an optical disk, it is preferable that the thickness is usually about 2 to 20 μm.

[0023]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. Parts in Examples are parts by weight.

Example 1 50 parts of the diqualylate compound of the formula (2), 10 parts of tetrahydrofuracrylyl acrylate, 20 parts of trimethylolpropane triacrylate, epoxy acrylate [epoxy resin of bisphenol A (Epicoat 82
8: Reaction product of Yuka Shell Epoxy Co., Ltd.) and acrylic acid] 20 parts and Irgacure-184 (Ciba Geigy Co., Ltd., photopolymerization initiator) 5 parts were mixed and dissolved, and the optical disk coating agent of the present invention was dissolved. I got

On a recording film of an optical disk having a recording film formed on a polycarbonate substrate (by sputtering),
The above-mentioned optical disk material was applied with a spin coater, and irradiated with a high-pressure mercury lamp (2KW, manufactured by Nippon Battery Co., Ltd.) to cure the material. The optical disk with the protective film was
When left in a state of 90% RH at 0 ° C. and subjected to a moisture resistance test, no abnormality was found in the recording film even after 2000 hours. Also, there was no reverse warpage or peeling.

Example 2 30 parts of the diacrylate compound of the formula (3), 40 parts of isobornyl acrylate, 20 parts of trimethylolpropane triacrylate, 10 parts of urethane acrylate (UV-7000B, manufactured by Nippon Gosei Co., Ltd.) Five parts of Irgacure 651 (a photopolymerization initiator manufactured by Ciba-Geigy) were mixed and dissolved to obtain a coating agent for an optical disk of the present invention. Using this, an optical disc having a protective film was obtained in the same manner as in Example 1. The test was performed in the same manner as in Example 1. As a result of the moisture resistance test, no abnormality was found even after lapse of 2,000 hours. Also, there was no reverse warpage or peeling.

Example 3 30 parts of the diacrylate compound of the formula (5), 20 parts of the diacrylate compound of the formula (2), 20 parts of neopentyl glycol diacrylate hydroxypivalate,
10 parts of tetrahydrofurfuryl acrylate, 20 parts of epoxy acrylate [a reaction product of bisphenol F type epoxy resin (Epicoat 807: manufactured by Yuka Shell Epoxy Co.) and acrylic acid] and Darocure 1173 (manufactured by Merck, photopolymerization initiator) 5) was mixed and dissolved to obtain a coating agent for an optical disk of the present invention. Using this, Example 1
In the same manner as in the above, an optical disk on which a protective film was formed was obtained.
A test was conducted in the same manner as in Example 1, and as a result of the moisture resistance test, 2
No abnormality was found even after 000 hours. Also, there was no reverse warpage or peeling.

Comparative Example 1 An optical disk was obtained in the same manner as in Example 1 except that SD-17 (trade name: manufactured by Dainippon Ink and Chemicals, Inc.) was used as a coating agent for an optical disk. A test was conducted in the same manner as in Example 1. As a result of the moisture resistance test, pitting corrosion occurred on the entire surface of the recording film after 2000 hours. Also, there was no reverse warpage or peeling.

[0029]

The coating agent for optical disks of the present invention has excellent moisture resistance, has no problem of reverse warpage or peeling, and is particularly useful as a protective coating agent for optical disk recording media.

Claims (1)

(57) [Claims] (1) Formula (1) (Wherein, n is an integer of 9 to 20). Diacrylate compound (A) represented by the formula (A), and 100 to 600 parts by weight of component (A) per 100 parts by weight of component (A) other than styrene and And / or a coating agent for an ultraviolet-curable optical disc, comprising a compound (B) containing an unsaturated group other than α-methylstyrene and a photopolymerization initiator (C).