JP3027263B2 - Coating composition and surface-coated molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition capable of forming a coating film having excellent abrasion resistance, abrasion resistance and solvent resistance by curing, 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 a resin.

[0002]

2. Description of the Related Art In recent years, a transparent plastic material having high crush resistance has been widely used as an alternative to a transparent glass sheet. However, transparent plastic materials have the serious drawback that they have a soft surface compared to glass, so they are easily worn and susceptible to scratching.

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

On the other hand, in order to impart a higher surface hardness to a molded product, for example, JP-A-48-26822 and JP-A-59-64
There is a method of applying an alkoxysilane compound to the surface of a plastic molded article and curing it by heat, as described in JP-A-6771. Further, for example, Japanese Patent Application Laid-Open No. Sho 56-10696
9, a method of applying a mixture of colloidal silica and an organic resin to the surface of a plastic molded product and curing the mixture with heat as described in JP-A-2-272204 or the like.
However, these methods require a drying step because a solvent is used. Further, the appearance of the coated molded article is liable to cause a problem, and it needs to be cured by heat, so that the energy consumption is large and the curing takes a long time, which is industrially disadvantageous.

Further, Japanese Patent Publication No. 2-60696 discloses that
There is a description of a plastic coating composition containing a powdery inorganic filler such as glass powder, finely divided silica, colloidal silica, and the like, and a polyfunctional (meth) acrylate as main components.
However, in this coating composition, the content of the inorganic filler in the composition cannot be increased because the dispersibility of the powdery inorganic filler (silica or the like) in the polyfunctional (meth) acrylate is not good. Therefore, only when the content of the inorganic filler is reduced, the coating composition exhibits operability as a coating solution. However, in this case, the surface hardness of the coating film is poor due to a low content of the inorganic filler and the like. On the other hand, when the content of the inorganic filler is increased to improve the surface hardness, the composition becomes a gel having no fluidity, and a solvent (diluent) must be used to apply the composition. A drying step is required prior to light curing or heat curing, resulting in poor productivity.

[0006]

SUMMARY OF THE INVENTION 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 that can be applied without using a solvent, and has excellent abrasion resistance, abrasion resistance, and solvent resistance by curing, and has a high surface hardness and a good appearance. And a molded article whose surface is coated with a cured product of the coating composition.

[0007]

The present invention relates to (a) a cross-linkable polymerizable compound (a) having at least two acryloyloxy groups and / or methacryloyloxy groups in a molecule;
-1) or a mixture comprising at least 50% by weight of the crosslinkable polymerizable 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 formed from a vinyl monomer, and (c) a polymerization initiator.

[0008] 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 a polymer formed from a vinyl monomer, the inorganic filler (b) and the crosslinkable polymerizable compound (a-1) This has the effect of improving the compatibility of Therefore, even if the content of the inorganic filler (b) is increased, a good dispersion state is maintained, and the above-mentioned object such as improvement of abrasion resistance can be achieved. Furthermore, the polymer is firmly united with the surface of the inorganic filler (b), so that the cured coating film exhibits excellent weather resistance and water resistance, and prevents the film from being cracked. Also.

Hereinafter, the present invention will be described in detail.

The polymerizable 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. Compound (a-1). The polymerization component (a) may be a mixture of 50% by weight or more of the crosslinkable polymerizable compound (a-1) and the compound (a-2) copolymerizable therewith.

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

As the crosslinkable polymerizable compound (a-1), for example, an ester compound obtained from a polyhydric alcohol and (meth) acrylic acid or a derivative thereof, or a polyhydric alcohol, a polycarboxylic acid and (meth) An ester compound obtained from acrylic acid or a derivative thereof is exemplified. As the polyhydric alcohol, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, having an average molecular weight of about 3
00 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 (that is, 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.

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

[0015]

Embedded image (In the formula, n represents 0 to 4, and four or more Xs in the molecule represent two or more (meth) acryloyloxy groups, and the rest each independently represent a hydrogen atom, a hydroxyl group,
It represents an amino group, an alkyl group or a substituted alkyl group. )
The compound represented by these is mentioned.

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, and tripentaerythritol hepta (meth) acrylate.

The crosslinkable polymerizable compound (a-1) is a polyhydric alcohol poly (meth) other than the compound of the above general formula (I).
Acrylates, such as 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 crosslinkable polymerizable compound (a-1), particularly preferred 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 And dipentaglycerol pentaacrylate.

The ester compound obtained from a polyhydric alcohol, a polycarboxylic acid and (meth) acrylic acid or a derivative thereof which can be used as the crosslinkable polymerizable compound (a-1) is basically a polyhydric alcohol. By reacting a mixture such that the hydroxyl groups of the above and the carboxyl groups of both the polyvalent carboxylic acid and the (meth) acrylic acid are finally equivalent. Preferred among these ester compounds are polyhydric alcohols, such as dihydric alcohols, trihydric alcohols, or mixtures of dihydric alcohols and trihydric alcohols, and dihydric carboxylic acids as polyhydric carboxylic acids. And esterified products obtained using the above. When a mixture of a trihydric alcohol and a dihydric alcohol is used, the molar ratio between the trihydric alcohol and the dihydric alcohol may be arbitrarily selected. The molar ratio of the dicarboxylic acid and the (meth) acrylic acid when used together is such that the carboxyl group of the dicarboxylic acid is 2 mol or less per 1 mol of the carboxyl group of (meth) acrylic acid. Is preferred. If the divalent carboxylic acid is in excess of the above range, the viscosity of the resulting 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, 3,6-endomethylenetetrahydrophthalic acid Alicyclic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, etc .; thiodiglycolic acid, thiodivalic acid, diglycolic acid, maleic acid, fumaric acid, itaconic acid, and their chlorides Products, anhydrides and esters.

Specific examples of the above ester compounds used as the crosslinkable polymerizable compound (a-1) include malonic acid / trimethylolethane / (meth) acrylic acid, malonic acid / trimethylolpropane / (meth) acrylic acid, 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 / pentane 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 by a combination of compounds such as (meth) acrylic acid, maleic anhydride / trimethylolethane / (meth) acrylic acid, maleic anhydride / glycerin / (meth) acrylic acid, etc. .

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

[0023]

Embedded image (Wherein R is each independently hexamethylene diisocyanate, tolylene diisocyanate, diphenylethane diisocyanate, xylene diisocyanate, 4,4 ′
-Represents the residue of methylene bis (cyclohexyl isocyanate), isophorone diisocyanate or trimethylhexamethylene diisocyanate. ) And an acrylic monomer having active hydrogen (eg, 2-hydroxyethyl (meth) acrylate, 2-hydroxy-3-methoxypropyl (meth) acrylate, N-methylol (meth) Acrylamide, N-hydroxy (meth) acrylamide, etc.)
And urethane (meth) acrylate obtained by reacting 1 mol or more of an acrylic monomer per 1 mol of isocyanate group by a conventional method; poly [such as tri (meth) acrylate of tris (2-hydroxyethyl) isocyanuric acid; (Meth) acryloyloxyethyl] isocyanurate.

The polymerizable component (a) in the coating composition of the present invention is, as described above, a crosslinkable polymerizable compound (a-1) 5.
It may be a mixture comprising 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 a molecule or the like 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, ethyl carbitol (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, represented by the following general formula (III) or (I
V)

[0025]

Embedded image (In the general formulas III and IV, n represents 1 to 10, X represents a (meth) acryloyloxy group, and R represents an alkyl group, a substituted alkyl group, a phenyl group, a substituted phenyl group, a benzyl group or a substituted benzyl group. Mono) (meth) acrylate represented by the following formula:

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, and butoxyethylene glycol (meth) acrylate. Acrylate and the like.

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 and urethane (meth) acrylates.

The inorganic filler (b) in the coating composition of the present invention has a surface modified with a polymer formed from a vinyl monomer. Here, “the surface has been modified with a polymer” means that the surface properties have been modified by fixing the polymer to some or all of the surface of the inorganic compound by any means. Therefore, the inorganic filler (b) is composed of, for example, a powdery inorganic compound and a polymer fixed on the surface thereof by grafting or adsorption.

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

As the vinyl monomer used to produce the polymer for modifying the surface of the inorganic filler (b), various known vinyl monomers capable of radical polymerization can be used. For example, methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate; methyl acrylate,
Acrylic acid 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; 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 A nitrogen-containing monomer 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 Crosslinking agents such as diacrylate, ethylene glycol dimethacrylate, allyl acrylate, allyl methacrylate, divinylbenzene, and trimethylolpropane triacrylate; and mixtures of these vinyl monomers. Of these, methacrylates, acrylates, and monomer mixtures containing methacrylates and / or acrylates as main components are preferred. 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 powdered inorganic compound can be changed in a wide range as desired. However, the polymer: inorganic compound (weight ratio) is preferably 1: 500 to 5: 1, and more preferably 1:50.
To 1: 1.

As a method for obtaining the inorganic filler (b) by modifying the surface of the inorganic compound with a polymer, various conventionally known methods can be used. That is, a mechanochemical method of crushing 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 polymerizing a vinyl monomer after electrically adsorbing a polymerization initiator to an inorganic compound in a dispersion of the inorganic compound (Polymer Transactions, Vol. 40, p. 259, 1983). After adsorbing hydroxypropylcellulose, the vinyl monomer is polymerized, and the surface of the inorganic particles is coated with an organic polymer and encapsulated.
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, p. 1923, 1990), using a vinyl monomer without a catalyst or a polymerization initiator in a polymerization system in which an inorganic compound is dispersed in the presence of a carboxylic acid or sulfonic acid monomer. Polymerization method (Japanese Unexamined Patent Publication No.
No. 149314, No. 57-115412, No. 62-
No. 50313) to obtain the inorganic filler (b).

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

The carboxylic acid monomer used in this method includes an active site having a carboxylic acid group as an active site for providing polymerization activity, and exhibiting strong cohesion between the produced polymer and the inorganic compound. Is essential, and all compounds having these functional groups can be applied. Specific examples include acrylic acid, methacrylic acid, crotonic acid, tiglic acid, cinnamic acid, and maleic acid. Particularly, acrylic acid and methacrylic acid are preferable because of their extremely high polymerization activity.

As the vinyl monomer used in this method, any ordinary vinyl monomer capable of undergoing radical polymerization can be used. Among them, methyl methacrylate has a particularly high polymerization activity, and furthermore, the resulting polymer and inorganic compound This is particularly preferred because of its good integration with. When a mixture of two or more monomers is used, it is preferable to use methyl methacrylate as one of the components, particularly from the viewpoint of polymerization activity.

In this method, the carboxylic acid monomer is used in an amount of about 0.05 to 100 parts by weight, preferably 0.1 to 100 parts by weight of the total amount of the inorganic compound and the vinyl monomer.
To 50 parts by weight, particularly preferably 0.5 to 30 parts by weight. The weight ratio of the monomer (carboxylic acid monomer and vinyl monomer) to the inorganic compound can be changed in 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 non-medium, then adding a carboxylic acid monomer and a vinyl monomer and stirring the mixture to homogenize the monomer mixture with the inorganic compound. For about 30 minutes to about 48 hours in an atmosphere of an inert gas such as nitrogen for about 10 to 10 hours.
It is carried out at a temperature of 100C, preferably 20-80C.

In particular, the inorganic filler (b) obtained by this method
Is because the polymer formed from the vinyl monomer firmly coalesced on the surface is excellent in compatibility with the crosslinkable polymerizable compound (a), so that the unmodified inorganic filler is crosslinked to a high concentration that cannot be dispersed. It can be dispersed in the polymerizable compound (a). Therefore, particularly, a cured product of the 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 coalesced on the surface of the inorganic filler, it exhibits excellent weather resistance and water resistance, and can cause cracks and the like in the coating film. Absent.

The mixing ratio of the inorganic filler (b) in the coating composition of the present invention is usually in the range of 5 to 200 parts by weight, preferably 5 to 200 parts by weight, per 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, particularly preferably 2 to 150 parts by weight.
When used in the range of 0 to 120 parts by weight, the desired performance in the present invention is particularly easily exhibited.

The polymerization initiator (c) in the coating composition of the present invention is not particularly limited as long as it can cause a 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 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 based on 100 parts by weight of the sum of the crosslinkable polymerizable compound (a) and the inorganic filler (b). Preferably it is in the range of 0.01 to 10 parts by weight. If the amount is too large, the cured coating film is colored or the weather resistance is lowered, which is not preferable.

Further, 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 the method of applying the coating composition to the surface of various molded articles include a brush coating method, a casting method, a roller coating method, a bar coating method, a spray coating method, an air knife coating method, a dipping method and the like. Although it is mentioned, it is not particularly limited.

As a method of curing the coating film formed by such a method to form a cured multilayer film, a method of curing by irradiating active energy rays such as ultraviolet rays and electron beams, and a method of curing by heat Etc. can be exemplified. A suitable method is employed depending on the type of the substrate and the mode of each component of the coating composition of the present invention.

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

According to the present invention, the molded articles having a film formed on the surface thereof are various known molded articles which are required to be improved in abrasion resistance and the like on the surface. In particular, synthetic resin molded articles are typically exemplified, for example, polymethyl methacrylate, a copolymer having methyl methacrylate as a main component, polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, polycarbonate, and 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. The measurement and evaluation of various physical properties in the examples were performed by the following methods.

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

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

3) Cohesiveness of the coating The sample was cut by eleven vertical and horizontal lines at 1 mm intervals with a razor blade to form 100 goban eyes, and the cellophane tape on the market was adhered well, and then 90 ° forward. The number of squares (x) when the film remains without peeling when the film is rapidly peeled off is indicated by x / 100.

4) Appearance Defects such as banding, spots, cracks, and cloudiness were visually determined and evaluated as follows. …: No noticeable defect. Δ: yellowish color of ΔYI value of 4.0 or more or slight cracking, clouding, etc. are observed. ×: Extremely impaired appearance.

<PMMA used as 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 formed from a vinyl monomer was prepared in the following manner with reference to the method described in (1).

That is, commercially available finely-divided silica fine powder (manufactured by Nippon Aerosil Co., Ltd., trade name Aerosil OX-
50) To 1000 parts by weight, add 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, and use a stirring grinder so that the silica fine powder is uniformly wetted. And mixed well. Thereafter, the mixture was packed in a polyethylene bag, the air inside was replaced with nitrogen as much as possible, the container was sealed, and allowed to stand at 60 ° C. for 24 hours. The silica fine powder whose surface was mainly modified with a polymer generated from methyl methacrylate was used. (PMMA-modified silica fine powder) was obtained.

<Example 1> 50 parts by weight of the PMMA-modified silica fine powder obtained in Preparation Example 1 was added to 50 parts by weight of 1,6-hexanediol diacrylate (hereinafter abbreviated as C ₆ -DA) while stirring. 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 and dissolved to obtain a coating composition.

This coating composition was coated on a polycarbonate plate (manufactured by Mitsubishi Rayon Co., Ltd., trade name: Dialite, thickness: 1 m).
m), and tightly pressed with a sponge roll while covering with a polyester film (manufactured by Diafoil Co., Ltd., thickness: 50 μm), and squeezed well so that the thickness of the coating film became about 7 μm. Next, a 120 W / cm metal halide lamp (with a parallel reflector, ozone-less type, distance 30 c from the object) adjusted to an irradiation width of 13 cm
m) was passed through at a speed of 2 m / min so that the polyester film surface side was irradiated. Next, the polyester film alone was peeled off, and further 2 m below a 120 W / cm high-pressure mercury lamp (with a parallel reflector, ozone type, irradiation width 13 cm, distance between the object and the lamp 30 cm).
/ Min to obtain a resin plate whose surface is protected by a cured film of the coating composition.

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

<Examples 2 to 9> Coating compositions of various compositions shown in Table 1 were prepared in the same manner as in Example 1 and polycarbonate plates (manufactured by Mitsubishi Rayon Co., Ltd., trade name: Dialite,
Resin whose surface is protected by a cured film by applying and curing it on a 1 mm thick) or polymethyl methacrylate plate (manufactured by Mitsubishi Rayon Co., Ltd., trade name: Acrylite, 1 mm thick) 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. Table 1 shows the results.

Example 10 PMMA-modified silica fine powder 50 obtained in Preparation Example 1 was mixed with 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). The parts by weight were added little by little while stirring, and dispersed uniformly. Then,
Benzoyl peroxide (hereinafter abbreviated as BPO)
The coating composition was obtained by adding and dissolving 5 parts by weight.

This coating composition is applied to a 1 mm-thick polycarbonate plate, and is tightly pressed with a sponge roll while covering the polyester film thereon, so that the thickness of the coating film is about 7 μm. I'm sorry. Next, this was placed in a thermostat adjusted to 120 ° C. for 30 minutes to cure, thereby obtaining a resin plate whose surface was protected by a cured film of the coating composition. This resin plate was evaluated in the same manner as in Example 1. Table 1 shows the results.

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

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

Comparative Example 3 An inorganic filler obtained by silane treatment with 5 parts by weight of γ-methacryloyloxypropyltrimethoxysilane was used in 50 parts by weight of commercially available silica fine powder (Aerosil OX-50, manufactured by Nippon Aerosil Co., Ltd.). , C ₆
-An attempt was made to disperse in 50 parts by weight of DA, but the fluidity was lost and coating on the substrate was impossible.

<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, and uniformly dispersed. Next, 1.7 parts by weight of APO and 0.6 parts by weight of BNP were added and dissolved to obtain a coating composition.

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

[0065]

[Table 1] (In the table abbreviations) 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 embodiments of the present invention described above are shown below.

The inorganic filler (b), the surface of which has been modified with a polymer formed from a vinyl monomer, contains at least one kind of polymer 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, wherein an organic polymer and an inorganic compound are tightly united, obtained by polymerizing a radically polymerizable vinyl monomer without a catalyst or using a polymerization initiator.

In the above embodiment, the coating composition according to the present invention, wherein the carboxylic acid monomer is (meth) acrylic acid.

The coating composition according to the present invention, wherein the vinyl monomer is methyl methacrylate or a monomer mixture containing 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 coating composition is excellent in abrasion resistance, scratch resistance and solvent resistance. High surface hardness and good appearance. Furthermore, it exhibits excellent weather resistance and water resistance, and is also effective in preventing the occurrence of cracks and the like in the film.

Since the surface-coated molded article of the present invention has its surface covered with the above-mentioned cured multi-layered film, various problems such as deterioration of aesthetics due to scratches, which have been a problem in conventional synthetic resin molded articles, have been observed. Eliminate problems.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Watanabe 20-1 Miyukicho, Otake City, Hiroshima Prefecture Examiner, Central Research Laboratory, Mitsubishi Rayon Co., Ltd. Masakatsu Kondo (56) References JP-A-11-92690 (JP) JP-A-10-330409 (JP, A) JP-A-63-246307 (JP, A) JP-A-63-265907 (JP, A) JP-A-57-149314 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) C09D 4/02 CA (STN) CAOLD (STN) REGISTRY (STN) WPIDS (STN) Practical file (PATOLIS)

Claims (3)

(57) [Claims] (1) 50% by weight of a crosslinked polymerizable compound (a-1) having at least two acryloyloxy groups and / or methacryloyloxy groups in a molecule, or the crosslinked 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 formed from a vinyl monomer, and (c) a polymerization initiator. Coating composition comprising: 2. The coating composition according to claim 1, wherein the vinyl monomer is methyl methacrylate. 3. A molded product having a surface coated with a cured product of the coating composition according to claim 1.