JP2002338889A - Coating composition, surface coated molded article and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition which can form a cured film having excellent weatherability, mar resistance, and film adhesion. SOLUTION: The coating composition comprises (a) a hydrolyzate of a silane compound to be represented by formula (I), (b) a hydrolyzate of a silane compound to be represented by formula (II): R<4> b -Si- (OR<5> )4-b (wherein R<4> is a 1-8C hydrocarbon group; R<5> is a 1-5C akyl group, an acyl group, an alkenyl group or an alkoxyalkyl group; and b is an integer of 0-3), and (c) a colloidal silica.

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 cured film having excellent weather resistance, abrasion resistance, and film adhesion, and to molding of a synthetic resin coated with the cured film of the coating composition. The present invention relates to a surface-coated molded product such as a product and a method for producing the same.

[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 and are therefore 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.
JP-A Nos. 02936 and 53-104638 and 5
A compound having a plurality of acryloyloxy groups or methacryloyloxy groups in a molecule as described in 4-97633 and the like is applied to the surface of a synthetic resin molded article,
There is a method of curing with an active energy ray such as heat or ultraviolet rays to obtain a surface-coated molded article having excellent scratch resistance. According to this conventional method, the curing liquid is relatively inexpensive and the productivity is excellent.
However, since this coating is an organic substance, the abrasion resistance is limited at present.

On the other hand, in order to impart a higher surface hardness to a molded product, for example, Japanese Patent Application Laid-Open Nos.
As described in JP-A-9-64671, there is a method of applying an alkoxysilane compound to the surface of a plastic molded article and curing it by heat. However, these methods have a problem in that the adhesion between the coating film and the synthetic resin molded product is not sufficient, so that the film adhesion after exposure is reduced.

A coating composition containing a hydrolyzate of a (meth) acryloxy group-containing alkoxysilane and a silica sol, as described in JP-A-62-231712, is applied to a mold, heated and dried. To form a thin film, and then inject the base resin material into the mold to carry out polymerization. However, in order to obtain sufficient film adhesion by this method, it is necessary to use a large amount of a hydrolyzate of a (meth) acryloxy group-containing alkoxysilane, and as a result, there is a problem that scratch resistance is reduced. .

[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 to provide a coating composition capable of forming a cured film having excellent weather resistance, abrasion resistance and film adhesion, and a molded article whose surface is coated with a cured film of the coating composition. It is in.

[0007]

The present invention provides (a) a hydrolyzate of a silane compound represented by the general formula (I):

[0008]

Embedded image (Wherein, R ¹ is a hydrogen atom or a methyl group, R ² is a carbon atom 1
To 3 alkyl groups or phenyl groups, R ³ represents a hydrogen atom or a hydrocarbon residue having 1 to 10 carbon atoms, and a represents an integer of 0 to 2. (B) a hydrolyzate of a silane compound represented by the general formula (II), and R ⁴ _b —Si— (OR ⁵ ) _4-b (II) (wherein, R ⁴ is a group having 1 to 8 carbon atoms) A hydrocarbon group, R ⁵ is an alkyl group, an acyl group, an alkenyl group or an alkoxyalkyl group having 1 to ⁵ carbon atoms, and b represents an integer of 0 to 3.) (c) Colloidal silica is contained. In the coating composition.

Further, the present invention provides a molded article whose surface is coated with a cured film of the coating composition and the coating composition on at least a part of the inner surface of a mold, and heat-drys the cured film to form a cured film. After the formation, the raw material of the resin molded product is injected into a mold and polymerized, so that at least a part of the surface is covered with a cured film of the coating composition.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

The component (a) contained in the coating composition of the present invention is a hydrolyzate of a silane compound represented by the general formula (I). Examples of the silane compound represented by the general formula (I) include p-vinylphenyltrimethoxysilane, p-vinylphenyltriethoxysilane, p-vinylphenyltriisopropoxysilane, p-vinylphenylmethyldimethoxysilane, p-vinyl Phenylmethyldiethoxysilane, p-vinylphenylethyldimethoxysilane, p-vinylphenylpropyldimethoxysilane, p-vinylphenylphenyldimethoxysilane,
p-vinylphenyldimethylmethoxysilane, o-vinylphenyltrimethoxysilane, o-vinylphenylmethyldimethoxysilane, m-vinylphenyltrimethoxysilane, o-vinylphenylmethyldimethoxysilane, p-isopropenylphenyltrimethoxysilane,
p-isopropenylphenylmethyldimethoxysilane,
Mention may be made of m-isopropenylphenyltrimethoxysilane and m-isopropenylphenylmethyldimethoxysilane.

Preferred silane compounds are p-vinylphenyltrimethoxysilane, p-vinylphenyltriethoxysilane, p-vinylphenylmethyldimethoxysilane, p-vinylphenylmethyldiethoxysilane and p-vinylphenyldimethylmethoxysilane. And more preferred silane compounds are p-vinylphenyltrimethoxysilane and p-vinylphenylmethyldimethoxysilane.

The hydrolyzate of the silane compound represented by the general formula (I) includes those in which a part or all of the alkoxy groups are substituted with hydroxyl groups and those in which the substituted hydroxyl groups are partially bonded. . These hydrolysates are produced, for example, by adding a silane compound to an acidic aqueous solution such as hydrochloric acid and stirring. The silane compounds represented by the general formula (I) may be used alone or in combination of two or more.

The hydrolyzate of the silane compound represented by the general formula (I) is contained in the coating composition preferably in an amount of 1 to 15 parts by mass, more preferably 2 to 10 parts by mass in terms of solid content. If the content is too low, the adhesion between the cured film and the base resin in the resulting synthetic resin molded article will decrease, and if the content is too high, the scratch resistance of the cured film tends to decrease.

The solid content of the hydrolyzate in the present invention refers to a theoretical value in a state where all the alkoxy groups of the silane compound are hydrolyzed and the hydroxyl groups are not bonded to each other.

The component (b) contained in the coating composition of the present invention is a hydrolyzate of a silane compound represented by the general formula (II). R ⁴ in the silane compound represented by the general formula (II) is a hydrocarbon group having 1 to 8 carbon atoms, and the hydrocarbon group may have a substituent, for example, a methyl group,
Ethyl group, n-propyl group, alkyl group such as i-propyl group, etc., other γ-chloropropyl group, vinyl group,
3,3,3-trifluoropropyl group, γ-glycidoxypropyl group, γ-methacryloxypropyl group, γ-
Examples include a mercaptopropyl group, a phenyl group, a 3,4-epoxycyclohexylethyl group, and a γ-aminopropyl group. When a plurality of R ⁴ are present, they need not all be the same and may be different groups. R ⁵ is an alkyl group, an acyl group, an alkenyl group or an alkoxyalkyl group having 1 to ⁵ carbon atoms. When a plurality of R ⁵ are present, they do not need to be the same and may be different groups.

Specific examples of the silane compound represented by the general formula (II) include trimethylmethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyl Triethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, phenyl (methyl) diethoxysilane, vinyltriethoxysilane, vinyl (methyl) triethoxysilane, vinyltris (β-methoxyethoxy ) Silane, γ-chloropropyltrimethoxysilane,
γ, γ, γ-trifluoropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-
Aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N
-Bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-
Aminopropyl (methyl) dimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyl (methoxyethoxy) silane, γ-glycidylpropyltriethoxysilane, 3, Examples thereof include 4-epoxycyclohexylpropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropyltriethoxysilane.

The hydrolyzate of the silane compound represented by the general formula (II) includes those in which part or all of an alkoxy group, an acyloxy group, an alkenyloxy group, an alkoxyalkoxy group is substituted with a hydroxyl group, and those having a substituted hydroxyl group. Include those partially condensed. These hydrolysates are:
For example, adding a silane compound to an acidic aqueous solution such as hydrochloric acid,
Manufactured by stirring. The silane compounds represented by the general formula (II) may be used alone or in combination of two or more.

The hydrolyzate of the silane compound represented by the general formula (II) is contained in the coating composition in an amount of preferably from 15 to 89 parts by mass, more preferably from 20 to 70 parts by mass in terms of solids. If the content is too low, the cured film becomes brittle and film formation becomes difficult. If the content is too high, the abrasion resistance of the cured film decreases.

In addition, the hydrolyzate of the silane compound represented by the general formula (I) and the hydrolyzate of the silane compound represented by the general formula (II) are necessarily produced separately and mixed. It is not necessary to use a compound obtained by co-hydrolyzing a mixture of a silane compound represented by the general formula (I) and a silane compound represented by the general formula (II).

The component (c) contained in the coating composition of the present invention is colloidal silica. The average particle size of colloidal silica is usually 1 nm to 1 μm and is not particularly limited, but a preferable average particle size is 10 nm to 500 μm.
nm. The dispersion medium is not particularly limited, but usually,
Water; alcohols such as methanol, ethanol, isopropyl alcohol, and n-butanol; cellosolves; aromatic hydrocarbons such as dimethylacetamide and xylene; Particularly preferred dispersion media are alcohols, cellosolves and water.

The colloidal silica is contained in the coating composition preferably in an amount of 10 to 70 parts by mass, more preferably 20 to 65 parts by mass in terms of solid content. If the content is too low, the abrasion resistance of the cured film decreases. If the content is too high, the cured film becomes brittle, making film formation difficult.

Thus, component (a), component (b)
The total amount of component (c) is 100 parts by mass in terms of solid content of the coating composition.

For curing the coating composition of the present invention
It is effective to use a curing accelerator in combination. This curing accelerator
As ammonium perchlorate, perchloric acid, hydrochloric acid, nitric acid
Acid, phosphoric acid, sulfuric acid, sulfonic acid, p-toluene sulfone
Acid, boron trifluoride and its complex with electron donor, Sn
Cl_Four, ZnCl_Three, FeCl_Three, AlCl_Three, SbC
l _Five, TiCl_FourLewis acids and their complexes;
Thorium, zinc naphthenate, cobalt naphthenate, octane
Organic acid metal salts such as zinc tillate and tin octylate;
Metal fluoride salts such as zinc iodide and tin borofluoride;
Organic esters of boric acid such as ethyl borate and methyl borate;
Metal hydroxides such as sodium hydroxide and potassium hydroxide;
Tetrabutoxytitanium, tetraisopropoxytitanium, etc.
Titanate esters; Glomer acetylacetonate
G, titanyl acetylacetonate, aluminum acetate
Tilacetonate, cobalt acetylacetonate, d
Metal acetylacetone such as nickel acetylacetonate
Salts; n-butylamine, di-n-butylamine,
L-n-butylamine, guanidine, piguanide, imine
Amines such as dazole;

The curing accelerator is preferably used in an amount of 0.01 to 10 parts by mass based on 100 parts by mass of the solid content of the components (a), (b) and (c). If the use ratio is too low, the curing acceleration property deteriorates. If the use ratio is too high, the storage stability of the coating composition deteriorates.

The coating composition of the present invention comprises component (a),
It is preferable to mix (b) and (c) uniformly, to adjust the solid content concentration, and to contain an organic solvent in order to improve the dispersion stability and storage stability of the solid content. Examples of the organic solvent include alcohols, ketones, ethers, cellosolves, esters, aromatic compounds, esters, and the like. Specifically, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, iso
Alcohols such as butanol, ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol monomethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone; ethers such as tetrahydrofuran and dioxane; methyl cellosolve, ethyl cellosolve; Cellosolves such as butyl cellosolve; aromatic compounds such as toluene and xylene; and esters such as ethyl acetate and butyl acetate. These can be used alone or in combination of two or more. The coating composition of the present invention preferably has a total solid content concentration of 50% by mass or less. If the total solid content is too high, the storage stability of the coating composition deteriorates.

In the coating composition of the present invention, various additives such as a surface smoothing agent, a surfactant, an ultraviolet absorber, a storage stabilizer and the like can be appropriately added as needed.

The method of applying the coating composition of the present invention to the surface of various molded articles includes 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 are not particularly limited. The coating amount of the coating composition on the surface of the molded product is such that the thickness of the cured film is 1 to 20 μm, preferably 2 to 20 μm.
It is applied so as to have a thickness of 10 μm. If the film thickness is too small, the scratch resistance deteriorates. If the film thickness is too large, cracks and the like tend to be easily formed in the cured film, which is not preferable.

As another method for forming a coating comprising the coating composition of the present invention on the surface of various molded articles, the coating composition is applied to at least a part of the inner surface of a mold, and is dried by heating and cured. After forming the film, there is a method in which at least a part of the surface is covered with a cured film by injecting a resin molded product raw material into a mold and polymerizing. At this time, by using a mold having minute irregularities on the inner surface, it is possible to obtain a molded product in which at least a part of the surface is covered with a cured film having minute irregularities. In addition, the surface is a fine uneven shape, and a film that does not swell or dissolve in the coating composition is attached to the inner surface of the mold, and the coating composition is applied to the fine uneven surface of the film, whereby the surface of the coating is coated. It is also possible to obtain a molded product at least partially covered with a cured film having a minute uneven shape.

According to the present invention, the molded articles having a film formed on the surface thereof are various molded articles which are required to have improved abrasion resistance and the like on the surface. In particular, synthetic resin molded articles are typically mentioned, for example, polymethyl methacrylate, a copolymer having methyl methacrylate as a main component, polystyrene, a styrene-methyl methacrylate copolymer, a styrene-acrylonitrile copolymer, a polycarbonate, and a cellulose acetate. A butyrate resin, a polyallyl diglycol carbonate resin, a polyvinyl chloride resin, a polyester resin, and the like are preferable, and polymethyl methacrylate and a copolymer containing methyl methacrylate as a main component are particularly preferable.

The coating composition of the present invention is applied to the inner surface of a mold, heated and dried, and then the raw material of the resin molded product is injected into the mold and polymerized. The material resin is not particularly limited as long as it is a synthetic resin that can generally be cast and polymerized, but is preferably an acrylic resin. Particularly, a methyl methacrylate homopolymer and a copolymer with another copolymerizable monomer containing methyl methacrylate as a main component are preferable.

The mold to which the coating composition of the present invention is applied is as follows:
Although not particularly limited, a material made of a material such as stainless steel or a glass plate is preferable.

The synthetic resin molded article having a coating layer comprising the coating composition of the present invention is excellent in appearance, film adhesion, scratch resistance and weather resistance.
It is very useful for applications such as lighting fixture covers, optical parts, and automobile-related parts.

[0034]

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) Adhesion to the base material After making 11 cuts at 1 mm intervals in the coating layer of the sample at intervals of 1 mm with a razor blade to make 100 grids, and making the cellophane tape adhere well, 45 ゜ before When the coating layer was abruptly peeled in the direction, the number N of squares when the coating layer remained without being peeled was determined and indicated by N / 100. 2) Appearance It was visually confirmed whether there was any abnormality. 3) Scratch resistance According to Taber abrasion test method, CS-10F wear wheel (TA
BER INDUSTRIES), one wheel 500
An abrasion test was performed on the coating layer of the sample at a load of 500 g at 500 rotations, and the haze value of the abraded portion was measured with a haze meter. The measurement of the haze was performed at four points on the track of the wear cycle, and the average value was calculated. Taber abrasion (%)
(Haze value after Taber test)-(Haze value before Taber test)
The value of 4) Weather resistance Sunshine weatherometer (Suga Test Instruments Co., Ltd.)
The sample was exposed to the coating layer for 1000 and 2000 hours under conditions of 63 ° C. and rain, and the appearance and adhesion were evaluated.

Example 1 In a reactor equipped with a stirrer, methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-13; hereinafter abbreviated as MTMS, equivalent to component (b)) 61.9. Parts by mass, p-vinylphenyltrimethoxysilane (trade name: KBM-140, manufactured by Shin-Etsu Chemical Co., Ltd.)
3, hereinafter abbreviated as VPTMS, equivalent to component (a)) 2.5
Parts by mass, isopropanol-dispersed colloidal silica (silica content 30% by mass, Nissan Chemical Industries, Ltd., trade name I
184.3 parts by mass of PA-ST (corresponding to component (c)) and 84.9 parts by mass of water were added, and the mixture was stirred at room temperature for 3 hours. Thereafter, 0.13 parts by mass of sodium acetate was added, and
Stir for 4 hours. Next, 44.8 parts by mass of isobutanol and 44.8 parts by mass of 1-methoxy-2-propanol were added and stirred to obtain a coating agent (A).

Methyl methacrylate was supplied to a reactor equipped with a cooling pipe, a thermometer and a stirrer, and heated with stirring while the internal temperature reached 80 ° C., and 2,2′-azobis-
0.05 parts by mass of (2,4-dimethylvaleronitrile) was added, and the mixture was further heated to an internal temperature of 90 ° C. and maintained at that temperature for 8 minutes, and then cooled to room temperature to obtain a polymerization rate of about 22%.
A syrup consisting of a mixture of a methyl methacrylate polymer having a viscosity of 1500 mPa · s at 20 ° C. and methyl methacrylate was obtained.

The coating agent (A) was coated with a bar coater using SUS30 having a length of 610 mm, a width of 460 mm and a thickness of 2 mm.
The coating was applied to four plates to a thickness of about 30 μm and dried by heating in a hot air drier at 120 ° C. for 5 minutes to form a coating layer having a thickness of 3 μm.

The two SUS plates thus treated are opposed to each other so that the coating layer is on the inside, and between them, 2,2'-azobis- (2,4-dimethylvaleronitrile) 0.05
The syrup to which the mass part was added was injected, the periphery was sealed with a soft vinyl chloride gasket, the interval between the SUS plates was adjusted to 2.7 mm, and the mixture was heated and polymerized at 80 ° C. for 30 minutes and then at 130 ° C. for 30 minutes. After cooling, the resin plate having a thickness of 2 mm was peeled off from the SUS plate to prepare a resin plate having a coating layer.

Table 2 shows the results of evaluation of the adhesion, appearance, scratch resistance and weather resistance of this resin plate.

Examples 2 to 5 and Comparative Examples 1 to 7
Were prepared in the same manner as in Example 1, and applied and cured in the same manner as in Example 1 to produce a resin plate having a coating layer. These resin plates were evaluated in the same manner as in Example 1. The results are shown in Table 2. The resin plates obtained in Examples 2 to 5
It had excellent scratch resistance, weather resistance, and film adhesion. In the resin plates obtained in Comparative Examples 1 and 5, the coating layer migrated to the resin plate, but no adhesion was obtained. Further, in the resin plates obtained in Comparative Examples 2 and 4, poor adhesion of the film occurred due to the exposure, and in the resin plate obtained in Comparative Example 3, the scratch resistance was deteriorated. Further, in Comparative Example 6, the coating layer did not move to the resin side, and in Comparative Example 7, a film could not be formed. As described above, none of the comparative examples could provide a synthetic resin molded article having excellent scratch resistance, weather resistance, and film adhesion.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

According to the process for producing a resin composition coated with the coating composition and the cured product of the present invention, a synthetic resin molding having a coating layer having excellent film adhesion, scratch resistance and weather resistance is provided. Goods are obtained.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C09D 183/07 C09D 183/07 // B29K 33:04 B29K 33:04 83:00 83:00 (72) Inventor Hatakeyama Kouki 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Otake Office F-term (reference) 4F100 AA20A AA20C AH06A AH06C AK25B AK52A AK52C AT00B BA02 BA03 BA06 BA10A BA10C BA15 CC00A CC00C EH312 EH90K GBJ 422 JK12C JK14 JL09 YY00A YY00C 4F204 AA21 AA33 AB04 AD11 AH17 AH47 EA03 EA04 EB01 EB22 EB23 4J038 DL031 DL122 HA446 KA04 KA06 NA03 NA11 NA12 PB02 PB07 PB08 PC02 PC03 PC08

Claims (5)

[Claims] 1. A hydrolyzate of a silane compound represented by the general formula (I): (Wherein, R ¹ is a hydrogen atom or a methyl group, R ² is a carbon atom 1
To 3 alkyl groups or phenyl groups, R ³ represents a hydrogen atom or a hydrocarbon residue having 1 to 10 carbon atoms, and a represents an integer of 0 to 2. (B) a hydrolyzate of a silane compound represented by the general formula (II), and R ⁴ _b —Si— (OR ⁵ ) _4-b (II) (wherein, R ⁴ is a group having 1 to 8 carbon atoms) A hydrocarbon group, R ⁵ is an alkyl group having 1 to ⁵ carbon atoms, an acyl group, an alkenyl group or an alkoxyalkyl group, and b represents an integer of 0 to 3.) (c) It contains colloidal silica. Coating composition. 2. Component (a) is 1 to 15 parts by mass in terms of solids, component (b) is 15 to 89 parts by mass in terms of solids, and component (c) is 10 to 70 parts by mass in terms of solids. The coating composition according to claim 1, which contains the composition. 3. A molded article having a surface coated with a cured film of the coating composition according to claim 1 or 2. 4. The molded article according to claim 3, wherein the base material of the molded article is an acrylic resin. 5. The coating composition according to claim 1 or 2 is applied to at least a part of the inner surface of a mold, and is heated and dried to form a cured film. A method for producing a molded article having at least a part of its surface covered with a cured film of a coating composition by polymerization.