JPH0517706A - Coating composition and surface modification method for resin molded article - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a coating composition for forming a cured film having excellent light resistance and abrasion resistance, and abrasion resistance for resin molded articles such as polycarbonate (PC) using the coating composition. Provided is a method for modifying the surface of a resin molded article, which imparts [Constitution] A (1) (di) pentaerythritol is a polyfunctional monomer selected from (meth) acrylic acid esters, and (2) (meth) acryloyloxy group is at least 2
Isocyanurate-based monomer, and (3) (meth)
100 parts by weight of a monomer mixture containing an acryloyloxy group, a monomer having at least one of a hydroxyl group, a cyclic ether bond and a chain ether bond, B ultraviolet absorber 3 to
A coating composition consisting of 35 parts by weight, 0.5 to 10 parts by weight of a C (meth) acrylic acid alkyl ester polymer and 0.1 to 10 parts by weight of a D photopolymerization initiator is applied to the surface of a PC resin molded product and irradiated with ultraviolet rays. A cured coating of 1 to 30 μm is formed on the surface of the molded product.

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 a method for modifying the surface of a resin molded article having improved abrasion resistance and weather resistance.

[0002]

2. Description of the Related Art Generally, polycarbonate resin is transparent,
It has excellent performance such as easy moldability, heat resistance and impact resistance.
A wide range of applications are being developed. However, since the surface hardness is insufficient, the surface is apt to be damaged, and the product yield is lowered and the aesthetic appearance is impaired, so that it is strongly required to improve the wear resistance.

Further, the polycarbonate resin is insufficient in weather resistance as compared with other synthetic resins, and when it is used outdoors, its appearance is remarkably deteriorated such as deterioration of transparency, cracking, crazing or increase of yellowish color. At present, it is not practically usable, and improvement of weather resistance is also strongly demanded. In particular, there are strong demands for improvement in both wear resistance and weather resistance for applications such as automobile headlight cover lenses, tail lamps, side lamp covers, and glazing materials for automobiles.

Various proposals have been made for improving the wear resistance and weather resistance of polycarbonate resin molded products.
Mostly related to the two coat system.

As a specific example of the two-coat type, a paint prepared by blending an ultraviolet absorber with an acrylic, melamine, urethane or silicone resin, an oligomer or a monomer on the surface of a polycarbonate resin molded product is applied to the surface of the molded product. After coating and then irradiating heat or active energy rays such as ultraviolet rays and electron beams to form a coating film, a coating consisting of acrylic, melamine, urethane or silicone is applied to this surface, and heat or There is a method of forming a crosslinked cured film by irradiating active energy rays such as ultraviolet rays and electron rays. The feature of this proposal is that the undercoat layer (primer layer) absorbs ultraviolet rays and the like that cause deterioration of the resin surface to prevent peeling and electrification of the coating to improve weather resistance.

However, a problem with the two-coat system is that the adhesion of the undercoat layer to the surface of the polycarbonate resin molded article is not only sufficient, but the adhesion of the interface between the undercoat layer and the overcoat layer (cured film) is sufficiently imparted. It is important that the adhesion between the layers greatly differs depending on the degree of cure of the undercoat layer coating. That is, in order to satisfy both the adhesiveness of the interface and the wear resistance, it is necessary to set the degree of curing of the undercoat layer within a certain range. In many cases, it is not easy from the standpoint of view, and it is generally difficult to obtain products with excellent performance of both. Further, in the case of the two-coat system, not only the treatment process is complicated, but also the treatment time becomes long and there are many economical disadvantages.

The inventors of the present invention fully recognized the problems in the case of such a two-coat system, and studied a cured coating provided with abrasion resistance, scratch resistance and weather resistance in the one-coat system. A coating composition containing a UV absorber and a specific thermoplastic resin in a monomer mixture containing a special polyfunctional monomer has excellent effects of improving wear resistance, scratch resistance and weather resistance. Was found (Japanese Patent Laid-Open No. 56-127635).
Issue). This composition is applied to the surface of a polycarbonate resin molded article, and then the molded article having a cured coating formed on the surface obtained by irradiating ultraviolet rays in an air atmosphere is subjected to a weather resistance test such as accelerated exposure or outdoor exposure. Also had good yellowing resistance, transparency and gloss retention, and was excellent in weather resistance.

[0008]

However, a cured coating formed from the above coating composition may show a decrease in transparency and gloss retention rate or yellowing in a long-term exposure test. Therefore, there has been a demand for a coating composition that can provide an even higher level of weather resistance.

[0009]

Therefore, as a result of intensive investigations by the present inventors to improve the weather resistance without lowering the wear resistance, a specific polyfunctional monomer was used as a component of a coating composition. The inventors have found that the weather resistance of the abrasion-resistant polycarbonate resin molded article can be improved by using it as the above, and have completed the present invention.

The gist of the present invention is as follows. 100 parts by weight of a monomer mixture having the following composition (1) pentaerythritol tri (meth) acrylate, pentaerythritol (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol At least one polyfunctional monomer selected from the group consisting of penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate 30 to 30
80% by weight, (2) general formula (I)

[0011]

[Chemical 2] (In the formula, n is an integer of 1 to 8 and at least two X are CH ₂ ═CH—C00— group, CH ₂ ═C (CH ₃ ) —
COO- _{group, CH 2 = CH-COO- (} CH 2) 5 -OC
O- _{group, CH 2 = C (CH 3} ) -COO- (CH 2) 5 -O
It is selected from the group of CO-groups, the rest being -OH groups. 5 to 50% by weight of a polyfunctional monomer represented by
And (3) 10 to 60% by weight of a monomer having one (meth) acryloyloxy group in one molecule and having at least one of a hydroxyl group, a cyclic ether bond and a chain ether bond in the molecule, B. UV absorber 3 to 35 parts by weight, C.I. (Meth) acrylic acid alkyl ester polymer 0.5
-10 parts by weight, and D.I. A coating composition comprising 0.1 to 10 parts by weight of a photopolymerization initiator, and the coating composition is applied to the surface of a polycarbonate resin molded product and irradiated with ultraviolet rays to form a film thickness of 1 to 30 μm on the surface of the polycarbonate resin molded product. The present invention relates to a method for modifying the surface of a resin molded article, which comprises forming a cured coating of the above.

Component A- (1) used in the present invention, that is, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate. The polyfunctional monomer selected from the group consisting of dipentaerythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate has excellent polymerization activity when exposed to ultraviolet rays in the air, and is cured by crosslinking. And exhibits a high degree of wear resistance. These monomers may be used alone or in combination of two or more.

The proportion of the monomer used is in the range of 30 to 80% by weight, preferably 40 to 70% by weight in the monomer mixture [A]. If the amount of the monomer is less than 30% by weight, curing in an air atmosphere becomes insufficient and the composition is in an uncured state, or wrinkles occur in the cured film to reduce transparency, or the composition is cured. However, a cured coating with sufficient abrasion resistance cannot be obtained. On the contrary, when it is used in excess of 80% by weight,
Although abrasion resistance and curability are improved, the flexibility of the coating deteriorates, so cracks may be generated by heating at high temperature, and also with respect to weather resistance, cracks may be observed over time in the coating. Like

Polyfunctional monomer A represented by the general formula (I)
The component (2) is an isocyanurate monomer, and specific examples thereof include tris (acryloyloxyethyl) isocyanurate, tris (methacryloyloxyethyl) isocyanurate, and caprolactone-modified tris (methacryloyloxy). Examples thereof include monomers such as ethyl) isocyanurate, caprolactone-modified tris (acryloyloxyethyl) isocyanurate, and bis (acryloyloxyethyl hydroxyethyl) isocyanurate. These monomers may be used alone or in combination of two or more. As these monomers, those produced by a well-known method and commercially available can be used. For example, trade name FA-7
31A commercially available tris (acryloyloxyethyl) isocyanurate (manufactured by Hitachi Chemical Co., Ltd.) can be mentioned.

The polyfunctional monomer A- (2) component is excellent in polymerization activity upon irradiation with ultraviolet rays in the air and is essential for improving weather resistance without lowering wear resistance of the cured film. It is an ingredient. Long-term weather resistance is improved by the combined use of the component A- (2), and the cured film is a more practical cured film that can withstand long-term exposure such as maintaining transparency and gloss of the cured film and reducing yellowing. Can be formed. Also A-
By using the component (2) together, the effect of improving the heat resistance is recognized, the occurrence of cracks is not recognized even in the heat resistance test at high temperature, and it becomes possible to form a more practical cured film.

The proportion of the monomer used is 5 to 50% by weight, preferably 10 to 40% by weight in the monomer mixture [A].
It is a range. If the amount of the monomer is less than 5% by weight, the effect of improving the weather resistance becomes insufficient, and if it exceeds 50% by weight, the abrasion resistance of the cured coating becomes insufficient, and the curability becomes insufficient. It becomes sufficient and the uncured state and the transparency decrease.

The monomer A- (3) component having one (meth) acryloyloxy group in one molecule and having at least one of a hydroxyl group, a cyclic ether bond and a chain ether bond in the molecule is Specifically, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate,
Examples thereof include tetrahydrofurfuryl (meth) acrylate, ethoxyethyl (meth) acrylate, ethylcarbitol (meth) acrylate, tetrahydrofurfuryloxyethyl (meth) acrylate, and caprolactone-modified tetrahydrofurfuryl (meth) acrylate.

These monomers are essential components for imparting adhesion to the polycarbonate resin molded product,
It is also a component for imparting smoothness and flexibility to the cured film. Further, it is excellent in polymerization activity upon irradiation with ultraviolet rays in the air, and the effect of improving the curability of the coating film is also recognized, and it is also a component necessary for forming a uniform and transparent wrinkle-free cured coating film. Among these, tetrahydrofurfuryl (meth) acrylate, tetrahydrofurfuryloxyethyl (meth) acrylate, and caprolactone-modified tetrahydrofurfuryl (meth) acrylate are preferable.
The monomer A- (3) component may be used alone, or
Also, two or more kinds may be used in combination.

The proportion of the monomer used is in the range of 10 to 60% by weight, preferably 20 to 50% by weight in the monomer mixture [A]. If the amount of the monomer is less than 10% by weight, the adhesion of the cured film is insufficient, and the curability is lowered, so that wrinkles are generated in the cured film and the transparency is insufficient. On the contrary, if it is used in an amount of more than 60% by weight, a cured coating having sufficient abrasion resistance cannot be obtained.

The above are the essential monomers constituting the monomer mixture [A].

The ultraviolet absorber [B] component used in the present invention is not particularly limited, and broadly includes light stabilizers for polymers, such as those similar to hindered amines, and the coating composition of the present invention. It is possible to use as long as it is uniformly dissolved in the composition and has good weather resistance, but from the viewpoint of good solubility and weather resistance improvement in the composition of the present invention, benzophenone-based, benzophenone-based A UV absorber having a maximum absorption wavelength in the range of 240 to 380 nm, which is a compound derived from a triazole type, a phenyl salicylate type, or a phenyl benzoate type, is desirable.

Specific examples of the ultraviolet absorber [B] include 2
-Hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone,
2-hydroxy-4-n-octoxybenzophenone,
4-dodecyloxy-2-hydroxybenzophenone, 2
-Hydroxy-4-octadecyloxybenzophenone,
2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4-dimethoxybenzophenone, phenyl salicylate, p-tert-butylphenyl salicylate, p- (1,1,3,3-tetramethyl Butyl) phenyl salicylate, 3-hydroxyphenylbenzoate, phenylene-1,3-dibenzoate, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-
5-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-te
rt-Butylphenyl) benzotriazole, 2- (2
-Hydroxy-5-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-4-octyloxyphenyl) benzotriazole and the like can be mentioned. These ultraviolet absorbers may be used alone or in combination of two or more.

The amount of the ultraviolet absorber [B] added is preferably in the range of 3 to 35 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of the monomer mixture [A]. If it is less than 3 parts by weight, the effect of improving the weather resistance of the abrasion-resistant polycarbonate resin molded article is not sufficient, and if it is used in excess of 35 parts by weight, the abrasion resistance of the crosslinked cured coating becomes insufficient and the cured product is cured. As a result, the property is deteriorated, and it becomes an uncured state, or a uniform cured film cannot be obtained even when cured.

The (meth) acrylic acid alkyl ester polymer [C] used by adding to the monomer mixture [A] is
A dispersion aid effect that can improve the adhesion of the crosslinked cured film to the substrate without deteriorating the film appearance such as transparency or smoothness, and can evenly disperse a large amount of ultraviolet absorber in the film. It is contained and is an essential component for improving the weather resistance of a polycarbonate resin molded article having excellent wear resistance.

A method for improving the weather resistance of a coating by adding an ultraviolet absorber to the coating is known, but a large amount of the composition for forming a coating having a highly crosslinked structure as in the present invention is used. It was not possible to disperse the UV absorber. That is, even if a large amount of the ultraviolet absorber is added to the coating composition, during curing of the coating composition, a large amount of the ultraviolet absorber is not sufficiently and uniformly retained in the crosslinked cured coating,
They may aggregate in the form of fine islands in the crosslinked cured coating, or they may be leached on the surface of the cured coating, and the entire coating may become cloudy white, or the surface hardness and abrasion resistance of the cured coating may be extremely reduced.

In fact, the crosslinked cured coating formed from the monomer mixture [A] of the present invention also contains only a small amount of an ultraviolet absorber. If a large amount of UV absorber is added in excess of this amount, various defects as described above will occur, and if the amount of UV absorber added is reduced, the above-mentioned problems will disappear, but the weather resistance will increase. The improvement effect is insufficient.

However, it has been found that the above problems can be solved all at once by adding a small amount of the above-mentioned (meth) acrylic acid alkyl ester polymer [C] to the coating composition of the present invention.

The (meth) acrylic acid alkyl ester polymer [C] used in the present invention has an intrinsic viscosity [η] (g / l) of 0.01, which is a measure of the polymer average molecular weight.
To 0.30, preferably a homopolymer of a monomer selected from alkyl (meth) acrylate having an alkyl group having 1 to 8 carbon atoms or a copolymer thereof. . When the intrinsic viscosity [η] of the (meth) acrylic acid alkyl ester polymer [C] is less than 0.01, the (meth) acrylic acid alkyl ester polymer [C]
When the effect of dispersing the ultraviolet absorber [B] in the cross-linked cured film by the above is not sufficient, and when it exceeds 0.30,
The solubility of the (meth) acrylic acid alkyl ester polymer [C] in the coating composition of the present invention may be insufficient, or the smoothness of the cured coating may be reduced. Also, when the number of carbon atoms in the alkyl group is 9 or more, the solubility of the (meth) acrylic acid alkyl ester polymer [C] in the coating composition becomes poor, and the smoothness and abrasion resistance of the cured film deteriorate. There is something to do.

Specific examples of the (meth) acrylic acid alkyl ester polymer [C] include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate and i-butyl (meth). ) Acrylate, amyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethyl-1-hexyl (meth) acrylate, 3-pentyl acrylate, 3-methyl-
Examples thereof include homopolymers of 1-butyl acrylate, 2-ethyl-1-butyl acrylate and 2-heptyl acrylate, and copolymers thereof. These polymers may be used alone or in combination of two or more.

The blending amount of the (meth) acrylic acid alkyl ester polymer [C] with respect to 100 parts by weight of the monomer mixture [A] is 0.5 to 10 parts by weight, preferably 1 to 6 parts by weight. is there. If the amount is less than 0.5 parts by weight, the ultraviolet absorber cannot be contained in a large amount, and the amount is 1
If the amount exceeds 0 part by weight, the smoothness and wear resistance of the crosslinked cured coating will be deteriorated.

When ultraviolet rays are used as the active energy rays, it is preferable to add a photopolymerization initiator [D] to the monomer mixture [A]. Specific examples of these compounds include benzoin. , Benzoin methyl ether,
Benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, p-
Methoxybenzophenone, 2,2-diethoxyacetophenone, α, α-dimethoxy-α-phenylacetophenone, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4′-bis (dimethylaminobenzophenone), 2-hydroxy- 2-methyl-1-
Carbonyl compounds such as phenylpropan-1-one,
Sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide, azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile, benzoyl peroxide, ditertiary butyl peroxide And the like, and acylphosphine oxide such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

The amount of the photopolymerization initiator [D] added is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the monomer mixture [A]. If too much is added, the yellowish color of the coating film is obtained. And the like, or the weather resistance is deteriorated, which is not preferable, and when the addition amount is too small, curing by ultraviolet rays becomes poor.

The above are the essential components constituting the present invention. The coating workability of the coating composition, the smoothness of the coating, the uniformity,
From the viewpoint of improving the adhesion to the substrate, it is preferable to apply using a suitable organic solvent.

Specific examples of the organic solvent include alcohols such as ethanol, isopropyl alcohol, n-propyl alcohol, iso-butyl alcohol and n-butyl alcohol, aromatic hydrocarbons such as benzene, toluene and xylene, Ketones such as acetone and methyl ethyl ketone, ethers such as dioxane, esters such as ethyl acetate, n-butyl acetate and iso-amyl acetate, polyhydric alcohol derivatives such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, methoxybutanol, methoxypropanol, etc. Is mentioned. These organic solvents may be used alone or in combination of two or more.

The amount of these organic solvents used is in the range of 10 to 2000 parts by weight based on 100 parts by weight of the monomer mixture [A]. When the amount of the organic solvent used is less than 10 parts by weight, it may not be possible to obtain a film having excellent smoothness and uniformity, and when it is used in excess of 2000 parts by weight, the film thickness of the film becomes thin. The wear resistance and the weather resistance may be deteriorated because of too much.

Further, if necessary, monomers other than the monomer mixture [A] component (UV, EB curing handbook-material edition / Polymer Society); light stabilizers (eg hindered amine type), antioxidant Agents, stabilizers such as thermal polymerization inhibitors, leveling agents, defoaming agents, thickeners, antistatic agents, surface active agents such as antifogging agents, etc. may be appropriately blended in the present coating composition and used. Good.

As a method of applying the coating composition of the present invention to, for example, the surface of a polycarbonate resin molded article, a method such as brush coating, flow coating, spray coating, spin coating or dip coating is adopted. The dip coating method is preferable from the viewpoints of coating workability, smoothness and uniformity of the coating, and the spray coating method is particularly preferable from the viewpoint of shape dependency of the molded product.

After applying the coating composition to the surface of the polycarbonate resin molded article, setting is performed at a temperature in the range of room temperature to 120 ° C. for a time in the range of 1 to 60 minutes for the purpose of improving the adhesion and smoothness of the coating. You can do it.

The coating amount of the coating composition is preferably such that the cured film has a thickness of 1 to 30 μm, preferably 3 to 10 μm. When the film thickness is less than 1 μm, sufficient surface hardness, abrasion resistance, and scratch resistance cannot be obtained, and when it exceeds 30 μm, the adhesion to the base material tends to decrease and the coating film tends to crack. Or

A known method of irradiating active energy rays such as α, β and γ rays may be used as a means for curing the coating film applied to the surface of the polycarbonate resin molded article, but the coating composition of the present invention is cured. It is preferable to use ultraviolet rays as a means for making it. As a light source for generating ultraviolet rays, ultraviolet lamps are generally used from the viewpoint of practicality and economy, and specific examples thereof include a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, and a metal halide lamp. To be

The ultraviolet irradiation atmosphere may be of course applied in an inert gas such as nitrogen, carbon dioxide or argon, but the monomer mixture [A] of the present invention is efficiently cured even in a normal atmosphere. It is possible and is economically the most preferable method.

Polycarbonate resin moldings having excellent surface properties such as abrasion resistance and weather resistance can be produced using the coating composition of the present invention, but other synthetic resin moldings such as thermoplastic resins can be manufactured. , Various synthetic resin molded articles regardless of thermosetting resin, specifically, polymethylmethacrylate resin, polyallyldiglycolcarbonate resin,
Sheet-shaped molded products, film-shaped molded products manufactured from polystyrene resin, acrylonitrile-styrene copolymer resin (AS resin), polyvinyl chloride resin, acetate resin, ABS resin, polyester resin, polymethacrylimide resin, polyamide resin, etc. It is also possible to impart wear resistance and light resistance to rod-shaped molded products and various injection molded products.

As the polycarbonate resin molded product, various molded products molded from a polycarbonate resin such as bisphenol type polycarbonate, aliphatic polycarbonate and diethylene glycol bisallyl carbonate, for example, injection molded products such as automobile headlamp lenses are
It is widely used by taking advantage of its excellent impact resistance, heat resistance and transparency. However, as a drawback, the surface hardness and weather resistance are insufficient, and improvement of these properties is strongly demanded. By using the coating composition of the present invention, a polycarbonate resin molded article excellent in wear resistance and weather resistance is obtained. Can be obtained.

[0044]

The present invention will be described in more detail with reference to the following examples. The evaluations in the examples were carried out by the following methods.

1. Abrasion resistance and abrasion resistance # 000 steel wool (product of Nippon Steel Wool Co., Ltd., Bonster (trade name)) was attached to a 25φ circular pad, and this pad was placed on the surface of the sample held on the reciprocating abrasion tester table. The sample was placed and scratched reciprocally 50 times under a load of 1000 g. The sample was washed with a neutral detergent and the haze value was measured with a haze meter. Abrasion resistance and scratch resistance are indicated by (haze value after scratching-haze value before scratching).

2. Adhesiveness 11 scratches on the surface of the sample with a razor, both vertically and horizontally.
Insert at intervals of 5 mm, make 100 squares, press cellophane tape (width 25 mm, made by Nichiban Co., Ltd.) against the squares, and peel off rapidly. The evaluation of adhesiveness is shown by the number of remaining squares / total squares (100).

3. appearance (1) Transparency The haze value (%) is shown using a haze meter.

(2) Crack It was visually observed and used as the following criteria.

◯: No cracks were generated Δ: Some cracks were generated ×: Innumerable cracks were generated (3) Yellowish color computer (Suga Test Instruments Co., Ltd., SH-
Displayed in yellowness (YI) using 4).

4. A weather resistance sunshine carbon weather meter (Suga Test Instruments Co., Ltd., WEL-SUN-DC type) was used for the test. Test conditions are black panel temperature 63 ± 3 ℃, rainfall 1
It was a 2 min / 60 min cycle. After the test, the appearance (transparency, cracks and Y · I) was evaluated according to item 3.

5. The sample was left in an atmosphere of heat resistance of 120 ° C. to 150 ° C. for 1 hour, taken out, and then the appearance (cracks) was observed.

Examples 1-3. Comparative Examples 1 to 3 The coating compositions shown in Table 1 were prepared and applied to a 3 mm thick injection molded plate (manufactured by General Electric, trade name; Lexan LS-2, color tone: 111) by a spray coating method. Then, after leaving at 40 ° C. for 5 minutes, the high pressure mercury lamp (manufactured by Eye Graphics Co., output 120 W / cm 2
² ) was used to cure under the condition that the total irradiation light amount of ultraviolet rays was 2500 mj / cm ² (wavelength 340 nm to 380 nm). The film thickness at this time was 5 microns. The results obtained are shown in Table 1.

[0053]

[Table 1] DPHA: dipentaerythritol hexaacrylate FA-731A: tris (acryloyloxyethyl)
Isocyanurate, Hitachi Chemical Co., Ltd. M-325: Caprolactone modified tris (acryloyloxyethyl) isocyanurate, Toagosei Co., Ltd. M-215: Bis (acryloyloxyethylhydroxyethyl) isocyanurate, Toagosei Co., Ltd. Manufactured by THF-A: terrahydrofurfuryl acrylate (meth) acrylic acid alkyl ester polymer: polyethyl methacrylate, intrinsic viscosity [η] 0.09 (g /
l) BIP: benzoin isopropyl ether BNP: benzophenone UV-A: 2- (hydroxy-5-tert-butylphenyl) benzotriazole, trade name Tinuvin-P
S (manufactured by Ciba-Geigy) UV-A: 2,4-dihydroxybenzophenone, trade name Biosorb 100 (manufactured by Kyodo Pharmaceutical Co., Ltd.).

Examples 4 to 5 and Comparative Examples 4 to 6 The coating compositions shown in Table 2 were prepared. Using this, processing was carried out according to Examples 1 to 3. The film thickness at this time was 5 microns. The results obtained are shown in Table 2.

[0055]

[Table 2]

[0056]

EFFECT OF THE INVENTION Polycarbonate resin moldings produced by using the coating composition of the present invention have not only excellent wear resistance and weather resistance, but also excellent adhesion to a base material and durability. It is extremely useful and is applied to applications such as automobile headlamp lenses, and its industrial value is great.

Continued front page    (72) Inventor: Takemoto             4-1-1 Sunadabashi, Higashi-ku, Nagoya-shi, Aichi               Mitsubishi Rayon Co., Ltd. Product Development Laboratory

Claims (2)

[Claims] 1. A. Monomer mixture 10 having the following composition
0 parts by weight (1) pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate 30-80% by weight of at least one polyfunctional monomer selected from the group consisting of pentaerythritol hexa (meth) acrylate (2) The following general formula (I): (In the formula, n is an integer of 1 to 8, and at least two X are CH ₂ ═CH—COO— group, CH ₂ ═C (CH ₃ ) —
COO- _{group, CH 2 = CH-COO- (} CH 2) 5 -OC
O- _{group, CH 2 = C (CH 3} ) -COO- (CH 2) 5 -O
It is selected from the group of CO-groups, the rest being -OH groups. 5 to 50% by weight of a polyfunctional monomer represented by
And (3) Monomer 10 having one (meth) acryloyloxy group in one molecule and having at least one of a hydroxyl group, a cyclic ether bond and a chain ether bond in the molecule.
-60% by weight, B.I. UV absorber 3 to 35 parts by weight, C.I. (Meth) acrylic acid alkyl ester polymer 0.5
-10 parts by weight, and D.I. A coating composition comprising 0.1 to 10 parts by weight of a photopolymerization initiator 2. The coating composition according to claim 1 is applied to the surface of a polycarbonate resin molded article and is irradiated with ultraviolet rays to form a cured film having a thickness of 1 to 30 μm on the surface of the polycarbonate resin molded article. A method for modifying the surface of a resin molded product.