JPH11323186A - Abrasion-resistant coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating composition having a high curing rate and improved storage stability and giving a cured product having a high hardness, reduced coloration and improved adhesion and abrasion resistance by incorporating at least trifunctional polyacrylate with N-vinylacetamide. SOLUTION: This composition comprises 30-95 wt.%, desirably, 50-90 wt.% at least trifunctional polyacrylate, 5-70 wt.%, desirably, 5-50 wt.% n- vinylacetamide and, optionally, 0.1-10 wt.%, desirably, 1-5 wt.% polymerization initiator, and 0-40 wt.%, desirably, 0-30 wt.% ethylenically unsaturated compound selected among tetrahydrofuryl (meth)acrylate, carbitol (meth)acrylate, acryloylmorpholine, N-vinylcaprolactam, phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecane (meth)acrylate, tripropylene glycol di(meth) acrylate, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abrasion-resistant coating composition, and more particularly to an abrasion-resistant coating composition suitable for a UV-curable abrasion-resistant plastic 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, UV-curable 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, see JP-A-56-598.
No. 78 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 shelf 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 conducted intensive studies and found that the hardness is high, the curing speed is high, the adhesion is excellent, and the coloration of the cured product is small, and the abrasion resistance is small. The present invention succeeded in providing a functional coating composition and completed the present invention. That is, the present invention provides (1) an abrasion-resistant coating composition comprising triacrylate or more functional polyacrylate (A) and N-vinylacetamide (B), (2) a photopolymerization initiator (C) (3) N-vinylacetamide (B) is present in the composition at about 2 to 60% by weight of the total composition (1).
The composition of any of the preceding claims.

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 acrylic groups in the molecule. The preferred number of acrylic groups is 3 to 10. Representative examples thereof include, for example, trimethylolpropane triacrylate, trimethylolpropane mono- or polypropoxytriacrylate, trimethylolpropane mono- or polyethoxytriacrylate, pentaerythritol triacrylate, tris (2-acryloyloxyethyl) isocyanate, di ( 2-acryloyloxyethyl) isocyanurate, pentaerythritol tetraacrylate, pentaerythritol mono or polypropoxy tetraacrylate, pentaerythritol mono or polyethoxy tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, Dipentaerythritol mono or polyethoxy Sa acrylate, dipentaerythritol mono- or poly propoxy hexaacrylate, dipentaerythritol mono- or polyhexamethylene glue de hexaacrylate and the like. Further, pentaerythritol triacrylate or a reaction product of dipentaerythritol pentaacrylate with an organic diisocyanate can also be mentioned. Examples of the organic diisocyanate include tolylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and xylylene diisocyanate.

The use ratio of the polyacrylate (A) is 30 to 95% by weight in the abrasion-resistant coating composition.
Is preferable, and particularly preferably 50 to 90% by weight.

In the present invention, N-vinylacetamide (B) is used. By using N-vinylacetamide (B), the storage stability is excellent, the curability is good, and the cured product can have a function excellent in adhesion to a substrate, coloring property, and the like. The amount of N-vinylacetamide (B) used is preferably from 5 to 70% by weight, particularly preferably from 5 to 50% by weight in the composition.

In the composition of the present invention, various ethylenically unsaturated compounds may be used as components other than the components (A) and (B). Representative examples of the ethylenically unsaturated compound include tetrahydrofurfuryl (meth) acrylate, carbitol (meth) acrylate, acryloylmorpholine, N-vinylcaprolactam, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, and tricyclodecane (Meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tricyclodecane dimethylol di (meth) acrylate, neopentyl glycol dihydroxypivalate di (meth) acrylate, bisphenol A polyethoxydi (meth) ) Acrylate, 1,9-nonanediol di (meth) acrylate, polyester di (meth) acrylate, bisphenol A epoxy di (meth) acryle Mention may be made of a door or the like. 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 0 to 40% by weight, particularly preferably 0 to 30% by weight, in the composition. These ethylenically unsaturated compounds are readily available on the market.

The composition of the present invention can be cured by a known method. For example, it can be cured by ultraviolet light. In the case of curing by ultraviolet rays, it is necessary to use a photopolymerization initiator (C). The photopolymerization initiator may be any known photopolymerization initiator, but is required to have good storage stability after compounding. Examples of such a photopolymerization initiator include benzoin alkyl ethers such as benzoin ethyl ether, benzoin isobutyl ether and benzoin propyl ether, 2,2-diethoxyacetophenone, 4′-phenoxy-2,2-dichloroacetophenone and the like. Acetophenone, 2-hydroxy-2-methylpropiophenone, 4′-isopropyl-
2-hydroxy-2-methylpropiophenone, 4'-
Propiophenones such as dodecyl-2-hydroxy-2-methylpropiophenone, benzyldimethylketal, 1-hydroxycyclohexylphenylketone (Irgacure 184, manufactured by Ciba-Geigy, Inc.), benzophenone, 4-benzoyl-4 '-Methyldiphenylsulfide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like. Particularly preferred are 1-hydroxycyclohexylphenyl 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 the photopolymerization initiator (C), 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 optionally contain a solvent, a non-reactive polymer resin, and various additives. There is no particular limitation on the solvent, for example, isopropyl alcohol,
Examples include methyl ethyl ketone, ethyl acetate, butyl acetate, toluene, xylene and the like. 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. Also, as various additives, leveling agent, defoaming agent, silane coupling agent, antioxidant,
Examples include an ultraviolet absorber, a light stabilizer, a polymerization inhibitor, a colorant, and an inorganic filler.

The composition of the present invention comprises (A) and (B), if necessary, a photopolymerization initiator (C), various ethylenically unsaturated compounds, a solvent, a non-reactive polymer resin, and various additives. It can be prepared by mixing and heating and dissolving.

The abrasion-resistant coating composition of the present invention comprises:
By applying and curing on the surface of the base material, various properties such as excellent abrasion resistance, chemical resistance, adhesion, and transparency are imparted. Examples of the substrate include various plastic substrates. Especially for coating applications, polycarbonate,
Polystyrene, methyl methacrylate, styrene methyl methacrylate copolymer, plastic lens coating and various shapes made of materials such as allyl diglycol carbonate, sheet-like plastic materials, such as polypropylene, polyethylene, polyvinyl chloride,
It can be suitably used for coating polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polymethyl methacrylate, polyamide (nylon), polymethylpentene, polyethersulfone, and the like. As a base material, in addition to these plastics, wood, metal, stone, paper and the like can be applied.

To coat a substrate using the abrasion-resistant coating composition of the present invention, for example, a dipping method,
A thin film of the abrasion-resistant coating composition is coated on a substrate by conventional techniques such as spin coating, spray coating, flow coating, gravure printing, and roller coating, and then heated or irradiated with energy rays such as ultraviolet rays. Then, the thin film may be cured. The thickness of the cured thin film is 1 to 30 μm, preferably about 2 to 10 μm.

[0015]

The present invention will be described below in more detail with reference to examples. Parts in Examples are parts by weight. Examples 1 to 4 and 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. The obtained composition is applied on a polyvinyl chloride resin having a thickness of 1 mm by a roll (thickness: about 5 μm), and then irradiated with 50 mJ / cm 2 at a position of 8 cm under a light source in which a high-pressure mercury lamp (lamp output: 2 kW) is arranged in parallel. (Conveyor speed 5 m / min) to obtain a test piece. The following test was performed on the test piece and the prepared wear-resistant coating composition. Table 1 shows the results.

Abrasion resistance: The test piece was evaluated by lightly rubbing it with # 000 steel wool. ○ ・ ・ ・ ・ Almost no damage. △ ... Slightly scratched. X: markedly damaged. Adhesion: The test piece was subjected to a cross cut-cellotape peel test.・ ・ ・: No peeling eyes and no missing eyes occur. Δ: Slight chipping is observed. C: peeling eyes and chipped eyes occurred. Colorability: A test piece and an unprocessed polyvinyl chloride resin plate (blank) were placed on white paper, and both were compared and observed. Shelf life: The prepared abrasion-resistant coating composition was left at 40 ° C. for one month, and the state was observed. ○ ・ ・ ・ ・ No abnormality at all. Δ: Slightly colored or thickened. ×: severe coloring, thickening or gelling.

[0017]

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 N-vinylacetamide 30 30 50 N-vinylpyrrolidone 30 50 1-hydroxycyclohexylphenyl ketone 55 55 55 p-methoxyphenol (polymerization inhibitor) 0.05 0.05 0.05 0.05 0.05------------------------ −−−−−−−−−−−−−−−−−− Abrasion resistance ○ ○ △ ○ △ Adhesion ○ ○ ○ ○ ○ Coloring ○ ○ ○ × × Shell life ○ ○ △ × ×

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

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

[0020]

The abrasion-resistant coating composition of the present invention has excellent shelf life, and its cured product has high hardness, excellent adhesion, and has little coloring of the cured product. Suitable for a hydrophilic coating composition.

Claims (3)

[Claims] 1. A polyacrylate (A) having three or more functional groups and N
A wear-resistant coating composition comprising vinylacetamide (B). 2. The composition according to claim 1, which contains a photopolymerization initiator (C). 3. The composition according to claim 1, wherein the N-vinylacetamide (B) is present in the composition in an amount of 5 to 70% by weight.