JPH11293145A - Wear-resistant coating composition for plastic and its cured product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wear-resistant composition having a large curing rate and excellent adhesivity to substrates and giving slightly colored cured products having high hardness by compounding specific acrylates. SOLUTION: This wear-resistant coating composition comprises (A) a polyacrylate having three or more functional groups and (B) 1,4- cyclohexanedimethanol monoacrylate. The component A is a compound having three or more acrylate groups, preferably a compound having three to ten acrylate groups, such as trimethylolpropane triacrylate. The composition comprises 30-95 wt.% of the component A and 5-70 wt.% of the component B. (C) An ethylenic unsaturated compound such as tetrahydrofurfuryl (meth) acrylate may further be added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an abrasion-resistant coating composition for plastics, and more particularly to an abrasion-resistant coating composition for plastics suitable for an ultraviolet-curable abrasion-resistant coating agent.

[0002]

2. Description of the Related Art There are many articles on the market using various plastics such as polycarbonate, polymethyl methacrylate, polystyrene, styrene-methyl methacrylate copolymer, polyvinyl chloride and polyester.
Since these materials are relatively soft and have poor wear resistance, it is common practice to apply a wear-resistant coating agent. Among the wear-resistant coating agents, ultraviolet-curing coating agents have been widely used because of their excellent appearance, energy saving, and the like, and various coating agents have been proposed. For example, JP-A-56-59
No. 878 and the like.

[0003]

Problems to be Solved by the Invention
No. 8 is characterized in that N-vinylpyrrolidone is contained in the composition, and is excellent in hardness, curing speed, adhesion and the like. However, when N-vinylpyrrolidone is used, the shell life is short, and the cured product tends to be colored, which is problematic in practical use.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies and found that they have high hardness, high curing speed, excellent adhesion, little coloring of cured products, The present invention succeeded in providing a wear-resistant coating composition and completed the present invention. That is, the present invention
(1) Trifunctional or higher polyacrylate (A) and 1,4-
An abrasion-resistant coating composition for plastics, which comprises cyclohexanedimethanol monoacrylate (B); (2) a cured product of the composition according to (1),
(3) A plastic product having the cured product layer according to (2). It is about.

In the present invention, a polyacrylate (A) having three or more functional groups is used. The trifunctional or higher polyacrylate (A) is a compound having three or more acrylate groups, preferably a compound having 3 to 10 acrylate groups, for example, trimethylolpropane triacrylate,
Trimethylolpropane mono or polypropoxy triacrylate, trimethylol propane mono or polyethoxy triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate,
Pentaerythritol mono or polypropoxy tetraacrylate, pentaerythritol mono or polyethoxy tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate,
Dipentaerythritol mono- or polyethoxyhexaacrylate, dipentaerythritol mono- or polypropoxyhexaacrylate, dipentaerythritol mono- or polyhexanolide hexaacrylate, and the like. And the like. Examples of the organic diisocyanate include tolylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and xylylene diisocyanate.

The proportion of the polyacrylate (A) used is preferably 30 to 95% by weight in the abrasion-resistant coating composition (excluding the solvent, the same applies hereinafter), particularly preferably 5 to 95% by weight.
0 to 90% by weight.

In the present invention, 1,4-cyclohexanedimethanol monoacrylate (B) is used. 1,4-cyclohexanedimethanol monoacrylate is 1,4
-It is obtained by subjecting cyclohexane dimethanol to acrylation with acrylic acid or an acrylate ester by a method such as esylation reaction or transesterification reaction, and is commercially available from Mitsubishi Chemical Corporation. The amount of 1,4-cyclohexanedimethanol monoacrylate (B) used is preferably from 5 to 70% by weight, particularly preferably from 5 to 50% by weight, in the wear-resistant coating composition.

In the composition of the present invention, various ethylenically unsaturated compounds may be used as components other than the components (A) and (B). Examples of the ethylenically unsaturated compound include tetrahydrofurfuryl (meth) acrylate, carbitol (meth) acrylate, acryloylmorpholine, N-vinylformamide, N-vinylcaprolactone, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, Tricyclodecane (meta)
Acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tricyclodecane dimethylol di (meth) acrylate, neopentyl glycol di (meth) acrylate hydroxypivalate, bisphenol A polyethoxydi (meth) acrylate, Examples thereof include 1,9-nonanediol di (meth) acrylate, polyester di (meth) acrylate, and bisphenol A epoxy di (meth) acrylate. One or more of these ethylenically unsaturated compounds can be mixed and used in an optional ratio as needed. The amount of the ethylenically unsaturated compound to be used is preferably from 0 to 40% by weight, particularly preferably from 0 to 30% by weight, in the wear-resistant coating composition. These ethylenically unsaturated compounds are readily available on the market.

The composition of the present invention can be cured by, for example, an electron beam or ultraviolet rays. In the case of curing by ultraviolet rays, it is necessary to use a photopolymerization initiator. As the photopolymerization initiator, any known photopolymerization initiator may be used, but in consideration of storage stability after blending, benzoin alkyl ether type, acetophenone type, propiophenone type, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone (Ciba Geigy Corporation)
Irgacure 184), benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 2,
4,6-trimethylbenzoyldiphenylphosphine oxide is preferred.

Benzoin alkyl ether photopolymerization initiators include, for example, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether and the like, and acetophenone photopolymerization initiators include
For example, 2,2-diethoxyacetophenone, 4'-phenoxy-2,2-dichloroacetophenone and the like, and as a propiophenone-based photopolymerization initiator, for example, 2-hydroxy-2-methylpropiophenone, 4'-isopropyl -2-hydroxy-2-methylpropiophenone,
4'-dodecyl-2-hydroxy-2-methylpropiophenone and the like. Particularly preferred are 1-hydroxycyclohexyl phenyl ketone, 2
-Hydroxy-2-methylpropiophenone and the like.

These photopolymerization initiators may be used singly or as a mixture of two or more kinds at an arbitrary ratio. When it is necessary to use a photopolymerization initiator, the amount used is usually
0.1 to 10% by weight of the composition, preferably 1 to 5%
% By weight.

The composition of the present invention may contain, if desired, a soluble or non-reactive polymer resin and various additives. The solvent is not particularly limited and may be, for example, isopropyl alcohol, methyl ethyl ketone, ethyl acetate, acetic acid. Butyl, toluene, xylene and the like can be mentioned. Examples of the non-reactive polymer resin include a polyester resin, an alkyd resin, a phenol resin, a polyurethane elastomer, an acrylic polymer, a styrene-containing polymer, and an epoxy resin. Further, examples of the additives include a leveling agent, an antifoaming agent, a silane coupling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a polymerization inhibitor, a colorant, an inorganic filler, and the like. .

The composition of the present invention comprises (A) and (B)
If necessary, it can be prepared by mixing and heating and dissolving various ethylenically unsaturated compounds, photopolymerization initiators and various components.

The coating composition for abrasion-resistant plastics of the present invention can be used for coating various plastic products such as polycarbonate, polystyrene, methyl methacrylate, styrene methyl methacrylate copolymer and allyl diglycol carbonate. Various shapes, sheet-like plastic materials, for example, polypropylene, polyethylene, polyvinyl chloride, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polystyrene,
Polymethyl methacrylate, polyamide (nylon),
It can also be used to coat polymethylpentene, polyethersulfone and the like.

The cured product of the present invention can be obtained by irradiating the above-mentioned wear-resistant coating composition for plastics of the present invention with an energy ray such as an electron beam or an ultraviolet ray according to a conventional method. This cured product has various properties such as excellent wear resistance and chemical resistance, adhesion, transparency, and non-coloring.

The plastic product of the present invention is a plastic product having the cured product layer of the present invention. The thickness of the cured product layer is preferably about 1 to 30 μm. This cured product layer
It gives plastic products excellent properties such as abrasion resistance and chemical resistance, adhesion, transparency and non-coloring. In particular, since the transparency and the non-coloring property are good, as the plastic product, a product that is not colored, for example, an optical product such as a plastic lens or a transparent product is preferable.

To produce the hard coat body of the present invention,
For example, the surface of a plastic product may be coated with the abrasion-resistant coating composition for plastics of the present invention, and then the coating composition may be cured by irradiating an energy beam such as an electron beam or an ultraviolet ray. The coating is
It can be done by conventional techniques including, for example, dipping, spinning, spraying, flow coating, gravure and roller coating.

[0018]

The present invention will be described below in more detail with reference to examples. Parts in the present invention are parts by weight. Examples 1 to 4 Comparative Examples 1 and 2 The components were mixed and dissolved according to the composition shown in Table 1 (the numerical values are parts by weight) to prepare a wear-resistant coating composition of the present invention. The obtained composition is 1 mm thick.
Roll on a polyvinyl chloride resin (thickness approx. 5μ)
m) and then irradiated with a high-pressure mercury lamp (lamp output 2 kW) at a position of 8 cm under a light source arranged in parallel at 500 mJ / cm 2 (conveyor speed 5 m / min). Various evaluations were performed on the coating. The evaluation was performed by the following method.

Abrasion resistance: The coating applied and cured by the above method was evaluated by rubbing it slightly with # 0000 steel wool. ○ ・ ・ ・ ・ Almost no damage. △ ... Slightly scratched. X: markedly damaged.

Adhesion: Cross-cut / cellotape peel test was performed on the coated and cured product by the above method.・ ・ ・: No peeling eyes and no missing eyes occur. Δ: Slight chipping is observed. C: peeling eyes and chipped eyes occurred.

Colorability: A polyvinyl chloride resin plate (blank) coated and cured by the above method and a non-coated polyvinyl chloride resin plate were placed on white paper, and both were compared and observed. ○ ・ ・ ・ ・ No abnormality at all. Δ: Slightly colored. ×: severely colored.

Shelf life: The prepared abrasion-resistant coating composition was observed at 40 ° C. for one month and then observed. ○ ・ ・ ・ ・ No abnormality at all. Δ: Slightly colored or thickened. ×: severe coloring, thickening or gelling.

[0023]

Table 1 Example Comparative Example 12 3 12 KAYARAD DPHA * 1 40 40 Pentaerythritol tetraacrylate 30 50 50 Pentaerythritol triacrylate 35 Trimethylolpropane triacrylate 30 30 KAYARAD MANDA * 2 5 1,4 -Cyclohexanedimethanol monoacrylate 30 30 50 N-vinylpyrrolidone 30 50 1-hydroxycyclohexyl phenyl ketone 55 55 55 P-methoxyphenol (polymerization inhibitor) 0.05 0.05 0.05 0.05 0.05 ──────────摩 耗 Abrasion resistance ○ ○ △ ○ △ Adhesion ○ ○ ○ ○ ○ Coloring ○ ○ ○ × × Shelf life ○ ○ ○ × ×

Note) * 1 KAYARAD DPHA: A mixture of dipentaerythritol penta and hexaacrylate manufactured by Nippon Kayaku Co., Ltd. * 2 KAYARAD MANDA: Neopentyl glycol diacrylate hydroxypivalate manufactured by Nippon Kayaku Co., Ltd.

As is clear from the evaluation results in Table 1, the composition of the present invention is excellent in abrasion resistance and adhesiveness, has little coloring of a cured product, and is excellent in shelf life.

[0026]

The coating composition for abrasion-resistant plastics of the present invention has excellent shelf life, and its cured product has the characteristics of high hardness, good adhesion, and little coloration. By using the initiator together
Suitable for abrasion-resistant coating compositions for UV-curable plastics.

Claims (3)

[Claims] An abrasion-resistant coating composition for plastics, comprising a polyacrylate having three or more functional groups (A) and 1,4-cyclohexanedimethanol monoacrylate (B). 2. A cured product of the composition according to claim 1. 3. A plastic product having the cured product layer according to claim 2.