JPH0673306A - Protective coating agent - Google Patents

Abstract

PURPOSE:To improve the marring resistance and antistatic properties of a coating film and the long-term stability of the coating surface by incorporating a specific photopolymerization initiator into a photocurable resin. CONSTITUTION:0.1-10wt.% photopolymerization initiator comprising a compound which has a quaternary ammonium group and a carbonyl group and is represented by the formula (A-R1-NR2R3R4)<+>X<-> (wherein A is a group consisting of two phenyl groups bonded through at least 1 carbonyl group; R1 is a 1-5C (un)substituted (oxy)alkylene; R2 and R3 each is a 1-5C (un)substituted alkyl; R4 is a 1-5C hydrocarbon group; and X is a monovalent anion) and 0.01-3wt.% at least one compound selected from among benzophenone, thioxanthone, and alkylthioxanthones are added to a photocurable resin comprising up to 50wt.% monofunctional (meth)acrylic ester, at least 15wt.% polyfunctional (meth)acrylic ester, and up to 50wt.% crosslinkable oligomer having a mol.wt. of 200-5,000.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective coating agent, and more specifically, it has excellent scratch resistance and antistatic ability, while suppressing stains on the disc surface such as bleeding due to aging, thereby reducing the surface of the disc. The present invention relates to a protective coating agent used for forming a protective coat excellent in long-term stability.

[0002]

2. Description of the Related Art Polycarbonate is used as a substrate for digital audio discs, optical discs, and magneto-optical discs for recording and reproducing information on an optical recording layer composed of a recording layer or a light reflecting layer, and reproducing information formed on the information recording layer. , A synthetic resin substrate such as amorphous polyolefin is used.

These resins have the characteristics of being optically homogeneous and highly transparent, and being excellent in moldability and mechanical strength, but have low surface hardness and are easily scratched on the substrate surface. As a result, the read sensitivity of the information recorded on the disc is lowered and an error is likely to occur.

Further, since the synthetic resin substrate is easily charged during use and easily adsorbs dust or dust on the surface, it also has drawbacks such as deterioration in signal reading sensitivity and error.

In order to solve such a problem, a surface protective coating agent has been developed which coats a resin composition which is cured by light or heat on a synthetic resin substrate and cures the resin composition to protect the substrate. There is.

Furthermore, in order to prevent the charging property of the substrate,
The protective coating agent is required to have antistatic ability, but when the antistatic agent is blended in the protective coating agent, the antistatic agent causes bleeding on the surface of the disk, which causes a problem in long-term stability. is there.

Therefore, at the same time as protecting the surface of the substrate, it also has an antistatic function for preventing the adhesion of dust, suppresses the contamination of the disk surface such as bleeding due to aging, and provides a protective coat excellent in long-term stability. There is a need for a protective coating agent to form.

[0008]

DISCLOSURE OF THE INVENTION The present invention forms a protective coat having excellent scratch resistance, antistatic ability, and suppressing contamination of the disc surface such as bleeding due to aging, and excellent long-term stability. The purpose is to submit the protective coating used for this purpose.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have used a compound having a quaternary ammonium group and a carbonyl group as a photopolymerization initiator. It was found that by doing so, a protective coating agent having a desired function was obtained, and the present invention was completed.

That is, in the present invention, a compound having a quaternary ammonium group and a carbonyl group is used as a photopolymerization initiator,
The present invention relates to a protective coating agent made of a photocurable resin, and a protective coating agent made of a photocurable resin, which further contains at least one compound selected from the group consisting of benzophenone, thioxanthone and alkylthioxanthone as a photopolymerization initiator.

The present invention will be described in detail below.

The compound containing a quaternary ammonium group and a carbonyl group in the present invention is a compound represented by the following general formula. _{(A-R 1 -NR 2 R} 3 R 4) + X - ( where, A is two phenyl groups, a group that is linked by at least one carbonyl group, _{R 1} is 1 to 5 carbon atoms Represents a substituted or unsubstituted alkylene group or oxyalkylene group, R ₂ and R ₃ each represent a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and R _2
4 represents a hydrocarbon group having 1 to 5 carbon atoms. Also, X is 1
Indicates a valent anion. ) A can be, for example, a benzophenone residue or a thioxanthone residue, and R ₁ is, for example, an alkylene group such as a methylene group, an oxyalkylene group such as an oxypropylene group, or a hydrogen atom of these groups. A substituted alkylene group / substituted oxyalkylene group in which at least one of them is substituted with a hydroxyl group can be exemplified.

Examples of R ₂ and R ₃ include an alkyl group such as a methyl group, or a substituted alkyl group in which one or more of these hydrogen atoms are substituted with a substituent, and R ₄ is A hydrocarbon group having 1 to 5 carbon atoms, for example, a substituted or unsubstituted alkyl group, hetero atom and / or
Alternatively, a (meth) acrylic acid ester residue containing an unsaturated bond and the like can be exemplified.

Further, as X, halogen, ClO ₄ ⁻ ,
Examples thereof include BF ₄ ⁻ and PF ₆ ⁻ .

Specific examples of such a compound include 4-
Benzoyl-N, N-dimethyl- [2- (1-oxo-
2-propenyloxy) ethyl] benzenemethanaminium bromide,

[0016]

[Chemical 1] 2-Hydroxy-3- (3,4-dimethyl-9-oxo-9H-thioxanthene-2-yloxy) -N, N, N
-Trimethyl-1-propanaminium chloride,

[0017]

[Chemical 2] 2-hydroxy-3- (4-benzoylphenoxy)-
N, N, N-trimethyl-1-propanaminium chloride monohydrate,

[0018]

[Chemical 3] 4-benzoyl-N, N, N-trimethylbenzenemethanaminium chloride

[0019]

[Chemical 4] An example is

These compounds having a quaternary ammonium group and a carbonyl group may be used alone or in benzophenone,
It is used in combination with a photopolymerization initiator such as thioxanthone and alkylthioxanthone.

Examples of the alkylthioxanthone in the present invention include 2-methylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone and 2,4-diethylthioxanthone.

The amount of the photopolymerization initiator added in the present invention is 0.1 to 10% by weight based on the coating agent. 10% by weight
If added over the range, the three-dimensional crosslink density of the formed coat layer may decrease.

When the amount added is less than 0.1% by weight, the efficiency of the initiator is practically equal to 0, which is not practical.

The protective coating agent in the present invention comprises the above-mentioned photopolymerization initiator, a photocurable resin and, if necessary, an additive.

The photocurable resin in the present invention is composed of at least one selected from monofunctional or polyfunctional acrylic acid esters, monofunctional or polyfunctional methacrylic acid esters, and crosslinkable oligomers.

As the monofunctional acrylic acid ester and methacrylic acid ester (hereinafter referred to as (meth) acrylic acid ester) in the present invention, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate,
Examples thereof include isobornyl acrylate and isobornyl methacrylate.

When the photocurable resin is composed of a plurality of compounds, the addition amount of the monofunctional (meth) acrylic acid ester is 50% by weight or less, preferably 5% by weight or more and 45% by weight or less. When added in excess of 50% by weight,
Since this compound is monofunctional, it may be difficult for the formed film to have a three-dimensional crosslinked structure.

The polyfunctional acrylic and / or methacrylic acid ester in the present invention means a bifunctional or higher functional (meth)
It is an acrylic acid ester.

Representative examples of the bifunctional (meth) acrylic acid ester used in the present invention include octaethylene glycol di (meth) acrylate and nonaethylene glycol.
Ludi (meth) acrylate, decaethylene glycol di (meth) acrylate, undeca ethylene glycol di (meth) acrylate, dodeca ethylene glycol di (meth) acrylate, trideca ethylene glycol Ludi (meth) acrylate, tetradecaethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, ethylene oxide modified Examples thereof include bisphenol A di (meth) acrylate and bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decanedi (meth) acrylate.

Typical examples of the tri- or higher functional (meth) acrylic acid ester used in the present invention include trimethylolpropane tri (meth) acrylate and pentaerythritol.
Lutri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, ethylene oxide modified penta Erythritol Tori (Meta)
Acrylate, ethylene oxide-modified pentaerythritol tetra (meth) acrylate, isocyanurate-ethylene oxide-modified tri (meth) acrylate, isocyanurate-ethylene oxide / ε-caprolactone-modified tri (meth) acrylate , Hexamethylene diisocyanate and glycerin adducts such as diacrylate and dimethacrylate.

The polyfunctional (meth) acrylic acid ester used in the present invention is preferably used in an amount of at least 15% by weight. If it is less than 15% by weight, the degree of cross-linking of the film cured by ultraviolet rays may be insufficient, and not only the initial physical properties such as adhesive strength may be deteriorated but also the adhesive strength in a moist heat atmosphere may be decreased.

The polyfunctional (meth) acrylic acid ester may be used alone or in combination of two or more.

Typical examples of the crosslinkable oligomer used in the present invention are polyester (meth) acrylate, polyether (meth) acrylate and polyurethane (meth).
Examples thereof include acrylate, epoxy (meth) acrylate, silicon (meth) acrylate, and the like.

Specific examples thereof include polyurethane diacrylate, spiroglycol urethane diacrylate, bisphenol A type epoxy acrylate, bisphenol F type epoxy acrylate, and phenol. -Lunovolac type epoxy acrylate, cresol-run novolac type epoxy methacrylate, polydimethylsiloxane dimethacrylate and the like can be mentioned.

When the photocurable resin is composed of a plurality of compounds, the addition amount of the crosslinkable oligomer is 50% by weight or less,
It is preferably 30% by weight or less.

These acrylates are useful as crosslinkable oligomers having high practical utility, but in addition to these, unsaturated polyesters, polyamides having active groups in the side chains, polyurethanes, polyesters, polysulfones, polyethersulfones, A resin obtained by modifying a resin such as polyphenylene oxide with an acrylic acid ester can also be sufficiently used.

The molecular weight of the crosslinkable oligomer used in the present invention can be used in a fairly wide range, but a molecular weight of 200 to 50,000 is preferable.

This crosslinkable oligomer may be used alone or in combination of two or more kinds.

The resin composition of the present invention contains hydroquinone monomethyl ether, t-butyl catechol, p-benzoquinone, 2,5-t-, in order to prevent thermal polymerization during production and dark reaction during storage. It is desirable to add a known thermal polymerization inhibitor such as butyl hydroquinone or phenothiazine.

Further, for the purpose of imparting uniform coatability and controlling the occurrence of coating defects such as orange peel and craters, at least one kind of leveling agent may be added to the coating agent. As the leveling agent, silicone type surfactants and fluorine type surfactants are generally known, and these can be used without particular limitation.

The addition amount of these is usually 0.01 to 3% by weight with respect to the coating agent.

[0042]

The photocurable resin composition of the present invention thus obtained, which is photocured under predetermined conditions, has enhanced scratch resistance of the substrate surface, low surface resistance value, and coating. It is a protective coating agent with excellent surface stability over time.

[0043]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 350 g of pentaerythritol triacrylate as a polyfunctional acrylic acid ester derivative and 50 of nonaethylene glycol diacrylate derived from PEG # 400.
0 g, bis (hydroxymethyl) tricyclo [5.2.
A coating agent base resin was prepared by mixing 50 g of 1.0 ^2,6 ] decane diacrylate and 100 g of 1,6-hexanediol diacrylate. Silicone-based paint additive (trade name: KP-30 manufactured by Shin-Etsu Chemical Co., Ltd.) as a leveling agent with respect to the total amount of the base resin.
6 ") and 4-benzoyl-N, N-dimethyl- [2- (1-oxo-2-) as an ultraviolet polymerization initiator.
50 g of propenyloxy) ethyl] benzenemethanaminium bromide was added and mixed well.

After coating 1.5 g of this coating agent on the non-grooved surface of a polycarbonate magneto-optical disk substrate having a diameter of 90 mm, a thickness of 10 μm was obtained by spin coating.
Which was then exposed to ultraviolet light and cured in a nitrogen atmosphere.

The cumulative irradiation dose of ultraviolet rays during this exposure is 65
It was 0 mJ / cm ² (λ = 365 nm).

A protective layer made of silicon nitride is sputtered on the groove side of this substrate to a thickness of 500 angstroms, and an alloy thin film made of terbium, iron and cobalt is laminated on the protective layer to a thickness of 0.1 μm. Then, a magnetic thin film layer was formed.

Next, on this magnetic thin film layer, silicon nitride was again sputtered at a thickness of 500 Å as a protective layer and aluminum was sputtered at a thickness of 800 Å as a reflective layer to form a laminated layer.

Further, a photoreactive coating agent made of a polyfunctional acrylate was applied on the aluminum layer in a film thickness of 10 μm, crosslinked and cured by irradiation of ultraviolet rays to form an overcoat to prepare a magneto-optical disk.

After humidity conditioning of this disk at 23 ° C. and 50% humidity, TERAOHM METER-50 manufactured by Kawaguchi Electric Co., Ltd.
3 was used to measure the surface resistance. The results are shown in Table 1.

The disc manufactured in this manner was heated at a temperature of 8
After being stored for 4000 hours in an environment of 0 ° C. and a humidity of 85% RH, the surface condition and the electrical characteristics by a drive tester were inspected. The inspection results are also shown in Table 1.

Example 2 750 g of pentaerythritol triacrylate as a polyfunctional acrylic acid ester derivative, 100 g of neopentyl glycol diacrylate, 50 g of bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane diacrylate, and A coating agent base resin was prepared by mixing 100 g of 1,6-hexanediol diacrylate. Based on the total amount of this base resin, 1 g of a silicone-based paint additive (trade name "KP-306" manufactured by Shin-Etsu Chemical Co., Ltd.) as a leveling agent, and 2-hydroxy-3- (3,4) as an ultraviolet polymerization initiator -Dimethyl-9-oxo-9H-thioxanthene-2-yloxy)
30 g of -N, N, N-trimethyl-1-propanaminium chloride was added and mixed well.

Using this coating agent, a coated substrate was prepared in the same manner as in Example 1, and a magneto-optical disk was prepared by sputtering and overcoating as in Example 1, and the same environmental preservation test was conducted. Then, the surface condition and electrical characteristics were inspected. The results are shown in Table 1.

Example 3 As a polyfunctional acrylic ester derivative, 750 g of pentaerythritol triacrylate, 100 g of neopentyl glycol diacrylate, 50 g of bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane diacrylate, and A coating agent base resin was prepared by mixing 100 g of 1,6-hexanediol diacrylate. Based on the total amount of this base resin, 1 g of a silicone-based paint additive (trade name "KP-306" manufactured by Shin-Etsu Chemical Co., Ltd.) as a leveling agent, and 2-hydroxy-3- (4-benzoyl) as an ultraviolet polymerization initiator 50 g of phenoxy) -N, N, N-trimethyl-1-propanaminium chloride monohydrate was added and mixed well.

Using this coating agent, a magneto-optical disk was prepared in the same manner as in Example 1, and the same environmental preservation test was carried out and inspected. The results are shown in Table 1.

Example 4 750 g of pentaerythritol triacrylate as a polyfunctional acrylic ester derivative, 100 g of neopentyl glycol diacrylate, 50 g of bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane diacrylate, and A coating agent base resin was prepared by mixing 100 g of 1,6-hexanediol diacrylate. Based on the total amount of this base resin, 1 g of a silicone-based paint additive (trade name "KP-306" manufactured by Shin-Etsu Chemical Co., Ltd.) as a leveling agent, and 4-benzoyl-N, N, N- as an ultraviolet polymerization initiator 50 g of trimethylbenzenemethanaminium chloride was added and mixed well.

Using this coating agent, a magneto-optical disk was prepared in the same manner as in Example 1, and the same environmental preservation test was carried out and inspected. The results are shown in Table 1.

Example 5 750 g of pentaerythritol triacrylate as a polyfunctional acrylic acid ester derivative, 100 g of neopentyl glycol diacrylate, 50 g of bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane diacrylate, and A coating agent base resin was prepared by mixing 100 g of 1,6-hexanediol diacrylate. Based on the total amount of this base resin, 1 g of a silicone-based paint additive (trade name "KP-306" manufactured by Shin-Etsu Chemical Co., Ltd.) as a leveling agent, and 4-benzoyl-N, N, N- as an ultraviolet polymerization initiator 20 g of trimethylbenzenemethanaminium chloride and 20 g of benzophenone were added and mixed well.

Using this coating agent, a magneto-optical disk was prepared in the same manner as in Example 1, and the same environmental preservation test was carried out and inspected. The results are shown in Table 1.

Example 6 As a polyfunctional acrylic ester derivative, 750 g of pentaerythritol triacrylate, 100 g of neopentyl glycol diacrylate, 50 g of bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane diacrylate, and A coating agent base resin was prepared by mixing 100 g of 1,6-hexanediol diacrylate. Based on the total amount of this base resin, 1 g of a silicone-based paint additive (trade name "KP-306" manufactured by Shin-Etsu Chemical Co., Ltd.) as a leveling agent, and 4-benzoyl-N, N, N- as an ultraviolet polymerization initiator 20 g of trimethylbenzenemethanaminium chloride and 20 g of dimethylthioxanthone were added and mixed well.

Using this coating agent, a magneto-optical disk was prepared in the same manner as in Example 1, and the same environmental preservation test was carried out and inspected. The results are shown in Table 1.

Comparative Example 1 As a polyfunctional acrylic ester derivative, 750 g of pentaerythritol triacrylate, 100 g of neopentyl glycol diacrylate, 50 g of bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane diacrylate, and A coating agent base resin was prepared by mixing 100 g of 1,6-hexanediol diacrylate. Based on the total amount of this base resin, 1 g of a silicone-based paint additive (trade name "KP-306" manufactured by Shin-Etsu Chemical Co., Ltd.) as a leveling agent, and 1 g of 1-hydroxycyclohexyl phenyl ketone as an ultraviolet polymerization initiator, antistatic Quaternary ammonium salt-based antistatic agent as an agent (Nippon Yushi Co., Ltd. trade name "Elegan 264")
Was added and mixed well.

Using this coating agent, a magneto-optical disk was prepared in the same manner as in Example 1, and the same environmental preservation test was carried out and inspected. The results are shown in Table 1.

Comparative Example 2 As a polyfunctional acrylic ester derivative, 750 g of pentaerythritol triacrylate, 100 g of neopentyl glycol diacrylate, 50 g of bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane diacrylate, and A coating agent base resin was prepared by mixing 100 g of 1,6-hexanediol diacrylate. Based on the total amount of this base resin, 1 g of a silicone coating additive (trade name "KP-306" manufactured by Shin-Etsu Chemical Co., Ltd.) as a leveling agent, and 1 g of 1-hydroxycyclohexyl phenyl ketone as an ultraviolet polymerization initiator, antistatic Nonionic antistatic agent (Daiichi Kogyo Seiyaku's trade name "Register PE13"
9 ") was added and mixed well.

Using this coating agent, a magneto-optical disk was prepared in the same manner as in Example 1, and the same environmental preservation test was carried out and inspected. The results are shown in Table 1.

[0066]

Claims (2)

[Claims] 1. A protective coating agent comprising a photocurable resin, which comprises a compound having a quaternary ammonium group and a carbonyl group as a photopolymerization initiator. 2. A protection comprising a photocurable resin, which comprises a compound having a quaternary ammonium group and a carbonyl group and at least one compound selected from the group consisting of benzophenone, thioxanthone and alkylthioxanthone as a photopolymerization initiator. Coating agent.