JPH05295296A - Coating composition and surface-coated formed material - Google Patents

Abstract

PURPOSE:To provide the subject composition composed of respective specific mixture, inorganic filler and polymerization initiator, applicable without using a solvent, having excellent abrasion resistance, scratch resistance, solvent resistance and appearance and useful for the coating of molded material, etc. CONSTITUTION:The objective composition is composed of (A) (i) a cross-linking polymerizable compound having >=2 (meth)acryloyloxy groups in one molecule [e.g. diethylene glycol di(meth)acrylate] or (ii) a mixture of >=50wt.% of the component (i) and a compound copolymerizable therewith [e.g. methyl (meth) acrylate], (B) preferably 20-120 pts.wt. (based on 100 pts.wt. of the component A) of an inorganic filler such as silicon dioxide surface-modified with a polymer derived from a vinyl monomer such as methyl methacrylate and (C) preferably 0.01-10 pts.wt. (based on 100 pts.wt. of A+B) of a polymerization initiator such as benzoin. It is preferable to coat the surface of a molded material with the cured product of the composition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a coating composition which can be cured to form a coating film having excellent abrasion resistance, scratch resistance and solvent resistance, and a cured film of the coating composition. The present invention relates to a surface-coated molded product such as a synthetic resin molded product coated with.

[0002]

2. Description of the Related Art In recent years, it has been widely used to use a transparent plastic material having high crush resistance as an alternative to transparent plate glass. However, the transparent plastic material has a serious drawback that it is easily worn and scratched due to its soft surface compared to glass.

Therefore, many attempts have heretofore been made to improve the wear resistance of plastic materials. One of the most common methods among them is disclosed in, for example, JP-A-53-1.
02936, 53-104638, 54-97.
No. 633, etc., a compound having a plurality of (meth) acryloyloxy groups in its molecule is applied to the surface of a synthetic resin molded article, and cured by an active energy ray such as heat or ultraviolet rays to scratch resistance. There is a method of obtaining a surface-coated molded article having excellent properties. In this conventional method, the curing liquid is relatively inexpensive and the productivity is excellent. However, since this coating film is an organic material, there is a limit to the abrasion resistance under the present circumstances.

On the other hand, in order to impart a higher surface hardness to a molded product, for example, JP-A-48-26822 and 59-64 are used.
There is a method of coating an alkoxysilane compound on the surface of a plastic molded article and curing it by heat as described in Japanese Patent Publication No. 671. Also, for example, Japanese Patent Laid-Open No. 56-10696
No. 9, JP-A-2-272041, etc., there is a method of coating a mixture of colloidal silica and an organic resin on the surface of a plastic molded article and curing it by heat.
However, since a solvent is used in these methods, a drying step is required. Further, the appearance of the coated molded product is apt to cause a problem, and since it is necessary to cure the coated molded product by heat, energy consumption is large and it takes a long time to cure, which is industrially disadvantageous.

Further, Japanese Patent Publication No. 2-60696 discloses that
There is a description of a plastic coating composition containing a powdered inorganic filler such as glass powder, fine silica or colloidal silica, and a polyfunctional (meth) acrylate as main components.
However, in this coating composition, the dispersibility of the powdery inorganic filler (silica or the like) in the polyfunctional (meth) acrylate is not good, so that the content of the inorganic filler in the composition cannot be increased. Therefore, only when the content of the inorganic filler is reduced, the coating composition exhibits operability as a coating liquid. However, in this case, the surface hardness of the coating film is poor due to the low content of the inorganic filler. On the other hand, when the content of the inorganic filler is increased to improve the surface hardness, the composition becomes a gel without fluidity, and a solvent (diluent) must be used to apply it. A drying step is required prior to photo-curing or heat-curing, resulting in poor productivity.

[0006]

The present invention has been made to solve the above-mentioned problems in the prior art. That is, an object of the present invention is a coating composition which can be applied without using a solvent, and is excellent in abrasion resistance, scratch resistance and solvent resistance by curing, and has a high surface hardness and a good appearance. It is intended to provide a coating composition capable of forming a film, and a molded article whose surface is coated with a cured product of the coating composition.

[0007]

The present invention provides (a) a crosslinkable polymerizable compound (a) having at least two acryloyloxy groups and / or methacryloyloxy groups in the molecule.
-1), or a mixture of 50% by weight or more of the crosslinkable compound (a-1) and a compound (a-2) copolymerizable therewith,
A coating composition comprising (b) an inorganic filler whose surface is modified with a polymer produced from a vinyl monomer, and (c) a polymerization initiator.

Still another aspect of the present invention is a molded article whose surface is coated with a cured product of the above coating composition.

[0009]

In the present invention, since the surface of the inorganic filler (b) is modified by the polymer formed from the vinyl monomer, the inorganic filler (b) and the crosslinkable polymerizable compound (a-1) Has the effect of improving the compatibility. Therefore, even if the content of the inorganic filler (b) is increased, a good dispersed state can be maintained, and the above-mentioned objects such as improvement of abrasion resistance can be achieved. Furthermore, by firmly coalescing the polymer on the surface of the inorganic filler (b), this cured coating film exhibits excellent weather resistance and water resistance, and prevents the occurrence of cracks in the film. Also becomes.

The present invention will be described in detail below.

The polymerization component (a) in the coating composition of the present invention is a crosslinkable polymer having at least two acryloyloxy groups and / or methacryloyloxy groups (hereinafter abbreviated as (meth) acryloyloxy groups) in the molecule. It is the compound (a-1). The polymerization component (a) may be a mixture of 50% by weight or more of the crosslinkable compound (a-1) and the compound (a-2) copolymerizable therewith.

A crosslinkable polymerizable compound (a-1) having at least two (meth) acryloyloxy groups in the molecule
Is a hydrocarbon or a derivative thereof which is a moiety other than (meth) acryloyloxy, and may have an ether bond, a thioether bond, an ester bond, an amide bond, a urethane bond or the like in its molecule.

Examples of the crosslinkable polymerizable compound (a-1) include ester compounds obtained from polyhydric alcohol and (meth) acrylic acid or derivatives thereof, or polyhydric alcohol and polycarboxylic acid (meth). Examples thereof include ester compounds obtained from acrylic acid or derivatives thereof. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and an average molecular weight of about 3
0 to about 1000 polyethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol (ie 2,2-dimethyl-1,3-propanediol), 2-ethylhexyl-1,3-hexanediol, 2,2′-thiodiethanol, 1,4-cyclohexane Dihydric alcohols such as dimethanol; trimethylolpropane (ie 1,1,1-trimethylolpropane), pentaglycerol (ie 1,1,1-trimethylolethane), glycerol, 1,2,4-butanetriol , Trihydric alcohols such as 1,2,6-hexanetriol; Other examples include pentaerythritol (that is, 2,2-bis (hydroxymethyl) -1,3-propanediol), diglycerol, dipentaerythritol, and the like.

Further, as an example of the crosslinkable polymerizable compound (a-1) obtained as a poly (meth) acrylate of a polyhydric alcohol, the following general formula (I) is used.

[0015]

[Chemical 1] (In the formula, n represents 0 to 4, and four or more Xs present in the molecule, two or more of them represent a (meth) acryloyloxy group, and the rest are each independently a hydrogen atom, a hydroxyl group,
An amino group, an alkyl group or a substituted alkyl group is shown. )
The compound represented by

The compound represented by the general formula (I) is
Specifically, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, pentaglycerol tri (meth) acrylate,
Pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate Acrylate, tripentaerythritol tetra (meth) acrylate, tripentaerythritol penta (meth) acrylate, tripentaerythritol hexa (meth) acrylate, tripentaerythritol hepta (meth) acrylate and the like.

The crosslinkable compound (a-1) is a poly (meth) alcohol of a polyhydric alcohol other than the compound of the above-mentioned general formula (I).
Acrylate, eg diethylene glycol di (meth)
Acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerin tri (meth) acrylate And so on.

When an ester compound obtained from a polyhydric alcohol and (meth) acrylic acid is used as the cross-linking polymerizable compound (a-1), particularly preferable ester compounds are diethylene glycol di (meth) acrylate and triethylene glycol di ( (Meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaglycerol triacrylate , Dipentaglycerol pentaacrylate and the like.

The ester compound obtained from the polyhydric alcohol, polyvalent carboxylic acid, and (meth) acrylic acid or their derivatives, which can be used as the crosslinkable compound (a-1), is basically a polyhydric alcohol. It can be obtained by reacting a mixture in which the hydroxyl groups of γ and the carboxyl groups of both polyvalent carboxylic acid and (meth) acrylic acid are finally equivalent. Among these ester compounds, preferred are dihydric alcohols, trihydric alcohols, or a mixture of dihydric alcohols and trihydric alcohols as polyhydric alcohols, and dihydric carboxylic acids as polyhydric carboxylic acids. The esterified product obtained by using. When a mixture of trihydric alcohol and dihydric alcohol is used, the molar ratio of trihydric alcohol and dihydric alcohol may be arbitrarily selected. When the divalent carboxylic acid and (meth) acrylic acid are used in combination, the molar ratio is such that the carboxyl group of the divalent carboxylic acid is 2 mol or less with respect to 1 mol of the carboxyl group of (meth) acrylic acid. Preferably. If the amount of the divalent carboxylic acid is more than the above range, the viscosity of the produced ester may be too high, which may cause difficulty in forming a coating film.

Examples of the divalent carboxylic acid or its derivative used in the synthesis of the above-mentioned ester compound include aliphatic dicarboxylic acids such as succinic acid, adipic acid and sebacic acid; tetrahydrophthalic acid and 3,6-endomethylenetetrahydrophthalic acid. Alicyclic dicarboxylic acids such as; phthalic acid, isophthalic acid, terephthalic acid and other aromatic dicarboxylic acids; other, thiodiglycolic acid, thiodivaleric acid, diglycolic acid, maleic acid, fumaric acid, itaconic acid, and chlorides thereof Compounds, anhydrides, esters and the like.

Specific examples of the above-mentioned ester compound used as the crosslinkable compound (a-1) include malonic acid / trimethylolethane / (meth) acrylic acid, malonic acid / trimethylolpropane / (meth) acrylic acid, and malon. Acid / glycerin / (meth) acrylic acid, malonic acid / pentaerythritol / (meth) acrylic acid, succinic acid / trimethylolethane / (meth) acrylic acid, succinic acid / trimethylolpropane / (meth) acrylic acid, succinic acid / Glycerin / (meth) acrylic acid, succinic acid / pentaerythritol / (meth) acrylic acid, adipic acid / trimethylolethane / (meth) acrylic acid, adipic acid / trimethylolpropane / (meth) acrylic acid, adipic acid /
Pentaerythritol / (meth) acrylic acid, adipic acid / glycerin / (meth) acrylic acid, glutaric acid / trimethylolethane / (meth) acrylic acid, glutaric acid / trimethylolpropane / (meth) acrylic acid, glutaric acid / glycerin / (Meth) acrylic acid, glutaric acid / pentaerythritol / (meth) acrylic acid, sebacic acid / trimethylolethane / (meth) acrylic acid, sebacic acid / trimethylolpropane / (meth) acrylic acid, sebacic acid / glycerin / (Meth) acrylic acid, sebacic acid / pentaerythritol / (meth) acrylic acid, fumaric acid / trimethylolethane / (meth) acrylic acid, fumaric acid / trimethylolpropane / (meth) acrylic acid, fumaric acid / glycerin / ( (Meth) acrylic acid, fumaric acid / penta Risuritoru / (meth) acrylic acid, itaconic acid / trimethylolethane / (meth) acrylic acid, itaconic acid / trimethylolpropane / (meth) acrylic acid, itaconic acid / pentaerythritol /
Saturated or unsaturated polyester polyacrylate or polymethacrylate, etc., which is a combination of compounds such as (meth) acrylic acid, maleic anhydride / trimethylolethane / (meth) acrylic acid, maleic anhydride / glycerin / (meth) acrylic acid ..

Further, as the crosslinkable polymerizable compound (a-1), for example, trimethylolpropane toluylene triisocyanate, the following general formula (II)

[0023]

[Chemical 2] (In the formula, each R independently represents hexamethylene diisocyanate, tolylene diisocyanate, diphenylethane diisocyanate, xylene diisocyanate, 4,4 ′.
Represents the residue of methylenebis (cyclohexylisocyanate), isophorone diisocyanate or trimethylhexamethylenediisocyanate. And a polyisocyanate such as a compound represented by the formula (1) and an acrylic monomer having active hydrogen (for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxy-3-methoxypropyl (meth) acrylate, N-methylol (meth)). Acrylamide, N-hydroxy (meth) acrylamide, etc.)
And a urethane (meth) acrylate obtained by reacting 1 mol or more of an acrylic monomer per 1 mol of an isocyanate group by a conventional method; and a poly [, such as tri (meth) acrylate of tris (2-hydroxyethyl) isocyanuric acid]. (Meth) acryloyloxyethyl] isocyanurate.

The polymerizing component (a) in the coating composition of the present invention is the cross-linking polymerizable compound (a-1) 5 as described above.
It may be a mixture of 0% by weight or more and the compound (a-2) copolymerizable therewith. This copolymerizable compound (a
As -2), for example, a compound having one (meth) acryloyloxy group in the molecule is used. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, iso-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl ( (Meth) acrylate, tridecyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-
Hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate,
1,4-butylene glycol mono (meth) acrylate, ethoxyethyl (meth) acrylate, ethylcarbitol (meth) acrylate, 2-hydroxy-3-
Chloropropyl (meth) acrylate, (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N
-Hydroxypropyl (meth) acrylamide, 2,
2,2-trifluoroethyl (meth) acrylate,
2,2,3,3-tetrafluoropropyl (meth) acrylate, 1H, 1H, 5H-octafluoropentyl (meth) acrylate, N-hydroxybutyl (meth)
Acrylamide, hydroxymethyl diacetone (meth)
Acrylamide, N-hydroxyethyl-N-methyl (meth) acrylamide, the following general formula (III) or (I
V)

[0025]

[Chemical 3] (In the general formulas III and IV, n represents 1 to 10, X represents a (meth) acryloyloxy group, R represents an alkyl group, a substituted alkyl group, a phenyl group, a substituted phenyl group, a benzyl group or a substituted benzyl group. Shown)), and the like.

Examples of the mono (meth) acrylate represented by the general formula III or IV include methoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, butoxyethylene glycol (meth). Acrylate etc. are mentioned.

Further as the copolymerizable compound (a-2), for example, β- (meth) acryloyloxyethyl hydrogen phthalate, β- (meth) acryloyloxyethyl hydrogen succinate, β- (meth) acryloyloxypropyl hydrogen succinate. And various known epoxy (meth) acrylates, urethane (meth) acrylates, and the like.

The inorganic filler (b) in the coating composition of the present invention has a surface modified with a polymer produced from a vinyl monomer. Here, "the surface is modified with a polymer" means that the surface characteristics are modified by fixing the polymer to a part or all of the surface of the inorganic compound by some means. Therefore, the inorganic filler (b) is composed of, for example, a powdered inorganic compound and a polymer fixed to the surface by grafting, adsorption or the like.

As the powdery inorganic compound which is the base material of the inorganic filler (b), for example, silicon dioxide (amorphous silica,
White carbon, colloidal silica, etc.), aluminum oxide, titanium oxide and the like. Of these, silicon dioxide is preferred. In addition, this powdered inorganic compound,
It may be treated with a coupling agent such as silane or titanium. The average particle size of the powdery inorganic compound is preferably 0.001 to 1 μm,
5 to 0.1 μm is more preferable.

As the vinyl monomer used for producing the surface modifying polymer of the inorganic filler (b), various known radically polymerizable vinyl monomers can be used. For example, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate; methyl acrylate,
Acrylic esters such as ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid; acid anhydrides such as maleic anhydride and itaconic anhydride; N- Maleimide derivatives such as phenylmaleimide, N-cyclohexylmaleimide and Nt-butylmaleimide; hydroxy group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate. Nitrogen-containing monomers such as acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, diacetone acrylamide, dimethylaminoethyl methacrylate; allyl glycidyl ether, glycidyl Epoxy group-containing monomers such as acrylate and glycidyl methacrylate; Styrene-based monomers such as styrene and α-methylstyrene; Silicon-containing monomers such as vinyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane; Ethylene glycol Cross-linking agents such as diacrylate, ethylene glycol dimethacrylate, allyl acrylate, allyl methacrylate, divinylbenzene, trimethylolpropane triacrylate; and mixtures of these vinyl monomers. Among these, preferred are methacrylic acid ester, acrylic acid ester, and a monomer mixture containing methacrylic acid ester and / or acrylic acid ester as a main component. Further, most preferred are methyl methacrylate and a monomer mixture containing methyl methacrylate as a main component.

In the inorganic filler (b), the weight ratio of the polymer to the powdery inorganic compound can be varied within a wide range as desired. However, the polymer: inorganic compound (weight ratio) is preferably 1: 500 to 5: 1, more preferably 1:50.
To 1: 1.

As a method for modifying the surface of the inorganic compound with a polymer to obtain the inorganic filler (b), various conventionally known methods can be used. That is, a mechanochemical method of pulverizing an inorganic compound in the presence of a reactive monomer to graft an organic polymer, a radiation method of irradiating an inorganic compound with high-energy radiation to graft an organic polymer,
A method of electrically adsorbing a polymerization initiator to an inorganic compound in a dispersion system of the inorganic compound and then polymerizing a vinyl monomer (Polymer Thesis, 40, 259, 1983). A method of adsorbing hydroxypropyl cellulose and then polymerizing a vinyl monomer to coat the surface of an inorganic particle with an organic polymer and encapsulate the polymer (Polymer Papers, 40 volumes,
697, 1983), a method of treating an inorganic compound with a silane coupling agent and then reacting the silane coupling agent with an organic polymer or monomer (J. Polym. S.
ci. , 28, page 1923, 1990, etc.), in the presence of a carboxylic acid or sulfonic acid type monomer and in which an inorganic compound is dispersed, a vinyl monomer is used without a catalyst or with a polymerization initiator. Method of polymerizing
-149314, 57-115412, 62-
No. 50313) and the like to obtain the inorganic filler (b).

Of the above-mentioned methods, the most preferable one to be used in the present invention is the carboxylic acid-based monomer in terms of easiness of the process, production cost and the strength of the bond between the inorganic compound and the organic polymer. In this method, a vinyl monomer is polymerized in a polymerization system in which an inorganic compound is dispersed in the presence of a body, without using a catalyst or a polymerization initiator. Hereinafter, this preferable method will be described.

The carboxylic acid-based monomer used in this method has an active site which has a carboxylic acid group as an active site which brings about polymerization activity and which exerts strong coalescence between the produced polymer and the inorganic compound. The presence of a double bond is essential, and all compounds having these functional groups are applicable. Specific examples thereof include acrylic acid, methacrylic acid, crotonic acid, tiglic acid, cinnamic acid, maleic acid, and the like, but acrylic acid and methacrylic acid are particularly preferable because of their extremely high polymerization activity.

As the vinyl monomer used in this method, any vinyl monomer which can be radically polymerized can be applied. Among them, methyl methacrylate has a particularly high polymerization activity, and the produced polymer and the inorganic compound can be used. It is particularly preferable because it has good compatibility with. When using a mixture of two or more kinds of monomers, it is particularly preferable to use methyl methacrylate as one component thereof in view of polymerization activity.

In this method, the carboxylic acid monomer is about 0.05 to 100 parts by weight, preferably 0.1 to 100 parts by weight, based on 100 parts by weight of the total amount of the inorganic compound and the vinyl monomer.
˜50 parts by weight, particularly preferably 0.5 to 30 parts by weight. The weight ratio of the monomer (carboxylic acid type monomer and vinyl monomer) to the inorganic compound can be varied within a wide range. However, polymer: inorganic compound (weight ratio)
Is about 500: 1 to 1: 5, preferably about 50: 1 to 1: 1.

The reaction is preferably carried out by dispersing the inorganic compound in a medium or a medium-free medium, then adding a carboxylic acid monomer and a vinyl monomer and stirring the mixture to homogenize the monomer mixture with the inorganic compound. Contact, for example, in an atmosphere of an inert gas such as nitrogen, for 30 minutes to about 48 hours, about 10
It is carried out at a temperature of 100 ° C., preferably 20-80 ° C.

In particular, the inorganic filler (b) obtained by this method
Is a polymer formed from a vinyl monomer that is strongly coalesced on the surface, and has excellent compatibility with the crosslinkable polymerizable compound (a). Therefore, the unmodified inorganic filler is crosslinked to a high concentration at which it cannot be dispersed. It can be dispersed in the polymerizable compound (a). Therefore, in particular, the cured product of this coating composition can impart excellent abrasion resistance and scratch resistance to the substrate. Furthermore, since the polymer formed from the vinyl monomer is particularly strongly united with the surface of the inorganic filler, excellent weather resistance and water resistance are exhibited, and cracks and the like may occur in the coating film. Absent.

The blending ratio of the inorganic filler (b) in the coating composition of the present invention is usually 5 to 200 parts by weight, preferably 5 to 200 parts by weight, relative to 100 parts by weight of the polymerization component (a). It is in the range of 150 parts by weight, more preferably in the range of 10 to 150 parts by weight, and particularly preferably 2
When it is used in the range of 0 to 120 parts by weight, the performance targeted by the present invention is particularly likely to be exhibited.

The polymerization initiator (c) in the coating composition of the present invention is not particularly limited as long as it can cause the polymerization reaction of the crosslinkable polymerizable compound (a). Specifically, benzoin, benzoin methyl ether,
Benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, acetoin,
Butyroin, toluoin, benzyl, benzophenone,
Carbonyl compounds such as p-methoxybenzophenone;
Sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile; peroxide compounds such as benzoyl peroxide and ditertiary butyl peroxide And phosphine oxide compounds such as trimethylbenzoyldiphenylphosphine oxide and benzoyldiethoxyphosphine oxide. These polymerization initiators may be used alone or in combination of two or more.

The mixing ratio of the polymerization initiator (c) is preferably in the range of 0.001 to 10 parts by weight with respect to 100 parts by weight of the sum of the crosslinkable polymerizable compound (a) and the inorganic filler (b). It is preferably in the range of 0.01 to 10 parts by weight. If the addition amount is too large, the cured coating film is colored or the weather resistance is deteriorated, which is not preferable.

In the coating composition of the present invention,
If necessary, surface smoothing agent, surfactant, UV absorber,
Various additives such as a storage stabilizer can be appropriately added and used.

Examples of methods for applying the coating composition to the surface of various molded articles include brush coating method, casting method, roller coating method, bar coating method, spray coating method, air knife coating method, dipping method and the like. Examples thereof include, but are not limited to.

As a method for curing the coating film formed by such a method to form a cured composite film, a method of irradiating with active energy rays such as ultraviolet rays or electron beams to cure or a method of curing with heat Etc. can be illustrated. A suitable method is adopted depending on the type of the substrate and the aspect of each constituent component of the coating composition of the present invention.

The coating amount of the coating composition on the surface of the molded article is preferably such that the film thickness is 1 to 30 μm. When the film thickness is less than 1 μm, abrasion resistance is poor, and when the film thickness exceeds 30 μm, cracks and the like tend to occur in the cured film, which is not preferable.

According to the present invention, the molded article on which a coating film is formed is any of various known molded articles which are required to have improved surface abrasion resistance and the like. In particular, synthetic resin moldings are typically mentioned, for example, polymethylmethacrylate, copolymer having methylmethacrylate as a main constituent, polystyrene, styrene-methylmethacrylate copolymer, styrene-acrylonitrile copolymer, polycarbonate, cellulose acetate. Butyrate resin, polyacrylic diglycol carbonate resin, polyvinyl chloride resin, polyester resin and the like are preferable.

[0047]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the examples. Moreover, the measurement and evaluation of various physical properties in the examples were carried out by the following methods.

1) Scratch resistance No. 000 steel wool was attached to a 25φ circular pad,
This pad was placed on the surface of a sample held on a reciprocating abrasion tester table and scratched 100 times under a load of 1000 g. After washing this sample, the haze value was measured with a haze meter. The scratch resistance (α) is represented by α = (haze value after scratch) − (haze value before scratch).

2) Wear resistance According to the Taber wear test method, CS-10F wear wheels and 50
A weight of 0 g was combined, and the haze value when rotated 100 times was measured with a haze meter. The haze value was measured at four locations around the orbit of the wear cycle, and the average value was calculated. Abrasion resistance (β) is represented by β = (haze value after Taber test) − (haze value before Taber test).

3) Adhesion of coating film The sample was cut with a razor blade at 1 mm intervals into 11 vertical and horizontal cuts to make 100 gobangs, and a commercially available cellophane tape was closely adhered to the sample. When the film is rapidly peeled off, the number of cells (x) when the film remains without peeling off is displayed as x / 100.

4) Appearance Defects such as banding, spots, cracks, and cloudiness were visually judged and evaluated as follows. ○: No particular defects. Δ: A yellowish color having a ΔYI value of 4.0 or more, or slight cracks, cloudiness, or the like was observed. ×: The appearance was extremely impaired.

<PMMA used as the inorganic filler (b)
Preparation Example 1 of Modified Silica Fine Powder> JP-A-57-149314
The inorganic filler (b) whose surface was modified with a polymer produced from a vinyl monomer was prepared as follows with reference to the method described in No.

That is, a well-stirred commercially available silica fine powder (trade name Aerosil OX-, manufactured by Nippon Aerosil Co., Ltd.)
50) To 1000 parts by weight, a mixture of 10 parts by weight of methacrylic acid, 150 parts by weight of methyl methacrylate, and 50 parts by weight of γ-methacryloyloxypropyltrimethoxysilane was added, and a stirring and crushing machine was used so that the fine silica powder was evenly wetted. Mixed well. Then, this mixture was packed in a polyethylene bag, the air in the bag was replaced with nitrogen as much as possible, then the bag was sealed, and allowed to stand at 60 ° C. for 24 hours, and silica fine powder whose surface was modified mainly with a polymer produced from methyl methacrylate. (PMMA-modified silica fine powder) was obtained.

<Example 1> 50 parts by weight of 1,6-hexanediol diacrylate (hereinafter abbreviated as C ₆ -DA) was added to 50 parts by weight of the PMMA-modified silica fine powder obtained in Preparation Example 1 while stirring. Each was added and dispersed uniformly. Next, 2.8 parts by weight of trimethylbenzoyldiphenylphosphine oxide (hereinafter, abbreviated as APO) and 1.0 part by weight of benzophenone (hereinafter, abbreviated as BNP) were added to and dissolved therein to obtain a coating composition.

A polycarbonate plate (manufactured by Mitsubishi Rayon Co., Ltd., trade name Diamond Light, thickness 1 m)
m) was coated, and a polyester film (manufactured by Dia foil Co., Ltd., thickness: 50 μm) was applied onto the m), and the mixture was tightly pressure-bonded using a sponge roll, and thoroughly squeezed to a thickness of about 7 μm. Next, a 120 W / cm metal halide lamp adjusted to an irradiation width of 13 cm (with a parallel reflector, an ozoneless type, a distance of 30 c from the object to be irradiated)
m) was passed under a speed of 2 m / min so that the polyester film surface side was irradiated. Then, only the polyester film is peeled off, and further 2 m under a 120 W / cm high pressure mercury lamp (with parallel type reflector, ozone type, irradiation width 13 cm, distance between subject and lamp 30 cm)
The resin plate whose surface was protected by the cured film of the coating composition was obtained.

The hardness, adhesion, and appearance of this resin plate were evaluated according to the methods described above. The results are shown in Table 1.

<Examples 2 to 9> Coating compositions having various compositions shown in Table 1 were prepared in the same manner as in Example 1, and a polycarbonate plate (manufactured by Mitsubishi Rayon Co., trade name Diamond,
A resin whose surface is protected by a cured film by applying and curing it on a polymethylmethacrylate plate (trade name: Acrylite, manufactured by Mitsubishi Rayon Co., Ltd., thickness: 1 mm) on a 1 mm thick) or polymethylmethacrylate plate in the same manner as in Example 1. I got a board. These resin plates were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 10 A mixture of 45 parts by weight of C ₆ -DA and ₅ parts by weight of 1H, 1H, 5H-octafluoropentyl acrylate (hereinafter abbreviated as 8FA) was added to 50 parts of PMMA-modified silica fine powder 50 obtained in Preparation Example 1. While stirring, parts by weight were added little by little and uniformly dispersed. Then to this,
Benzoyl peroxide (hereinafter abbreviated as BPO) 0.
A coating composition was obtained by adding and dissolving 5 parts by weight.

This coating composition was applied to a polycarbonate plate having a thickness of 1 mm, and while being covered with a polyester film, the composition was tightly pressure-bonded using a sponge roll so that the thickness of the applied film was about 7 μm. Got it. Then, this was placed in a constant temperature bath adjusted to 120 ° C. for 30 minutes to be cured to obtain a resin plate whose surface was protected by a cured film of the coating composition. This resin plate was also evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 A coating composition was prepared in the same manner as in Example 1 except that PMMA-modified silica fine powder was not added. Using this coating-like composition containing no inorganic filler (b), a cured coating film was formed on the surface of a polycarbonate plate in the same manner as in Example 1. This resin plate was also evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 An attempt was made to disperse 50 parts by weight of commercially available fine silica powder (Aerosil OX-50, trade name, manufactured by Nippon Aerosil Co., Ltd.) in 50 parts by weight of C ₆ -DA.
It became a white lump, lost its fluidity, and could not be applied to the substrate.

Comparative Example 3 An inorganic filler silanized with 5 parts by weight of γ-methacryloyloxypropyltrimethoxysilane was added to 50 parts by weight of commercially available silica fine powder (trade name Aerosil OX-50 manufactured by Nippon Aerosil Co., Ltd.). , C ₆
An attempt was made to disperse it in 50 parts by weight of DA, but the fluidity was lost and it was impossible to apply it to the substrate.

Comparative Example 4 To 50 parts by weight of C ₆ -DA, 10 parts by weight of a commercially available silica fine powder (trade name Aerosil R-972 manufactured by Nippon Aerosil Co., Ltd.) was added little by little with stirring to uniformly disperse the mixture. Next, 1.7 parts by weight of APO and 0.6 parts by weight of BNP were added to and dissolved in the mixture to obtain a coating composition.

However, this coating composition lost its fluidity after standing for a while, and coating on the substrate became impossible. Therefore, after stirring again, it was immediately coated on the substrate, and the composition of Example 1 was used. A surface protective layer was provided on a polycarbonate plate by the same method, the performance of the coating film was evaluated, and the obtained results are shown in Table 1.

[0065]

[Table 1] (Abbreviations in the table) C ₆ -DA: 1,6-hexanediol diacrylate 8FA: 1H, 1H, 5H-octafluoropentyl acrylate TEGDA: tetraethylene glycol diacrylate TAS: trimethylolethane / acrylic acid / succinic acid ( Condensate having a molar ratio of 2/4/1) TMPTA: trimethylolpropane triacrylate THFA: tetrahydrofurfuryl acrylate APO: trimethylbenzoyldiphenylphosphine oxide BNP: benzophenone BPO: benzoyl peroxide PC: polycarbonate PMMA: polymethyl methacrylate.

Representative examples of the preferred embodiment of the present invention described above are shown below.

The inorganic filler (b), the surface of which is modified with a polymer formed from a vinyl monomer, contains at least one inorganic filler in a polymerization system in which an inorganic compound is dispersed in the presence of a carboxylic acid monomer. The coating composition of the present invention, which is obtained by polymerizing a radically polymerizable vinyl monomer with no catalyst or with a polymerization initiator, and which is a strong coalescence of an organic polymer and an inorganic compound.

In the above aspect, the coating composition of the present invention, wherein the carboxylic acid monomer is (meth) acrylic acid.

The coating composition of the present invention, wherein the vinyl monomer is a monomer mixture containing methyl methacrylate or methacrylate as a main component.

[0070]

The coating composition of the present invention can be applied without using a solvent, and the coating film formed by applying and curing the same has excellent abrasion resistance, scratch resistance and solvent resistance. The surface hardness is high and the appearance is good. Furthermore, it also exhibits excellent weather resistance and water resistance, and is effective in preventing the occurrence of cracks in the film.

Further, since the surface-coated molded article of the present invention has its surface covered with the above-mentioned cured composite film, for example, various kinds such as deterioration of aesthetics due to scratches which have been a problem in the conventional synthetic resin molded articles. You can solve the problem.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Jin Shita, No. 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Institute (72) Hiroyuki Watanabe No. 20 Miyukicho, Otake City, Hiroshima Prefecture Central Research Laboratory, Mitsubishi Rayon Co., Ltd.

Claims (3)

[Claims] 1. A crosslinkable polymerizable compound (a-1) having (a) at least two acryloyloxy groups and / or methacryloyloxy groups in the molecule, or 50% by weight of the crosslinkable polymerizable compound (a-1). A mixture of the above and a compound (a-2) copolymerizable therewith, (b) an inorganic filler whose surface is modified with a polymer produced from a vinyl monomer, and (c) a polymerization initiator A coating composition comprising: 2. The coating composition according to claim 1, wherein the vinyl monomer is methyl methacrylate. 3. A molded product whose surface is coated with the cured product of the coating composition according to claim 1.