JPH06240199A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain a coating composition excellent in scratch resistance, transparency, heat resistance, weatherability and adhesiveness, comprising a silicate oligomer having specific structure, a specific acrylic copolymer, organic solvent and curing catalyst. CONSTITUTION:This coating composition comprises (A) a silicate oligomer of the formula ((n) is 1-20; R is CH3, C2H5, etc.) (e.g. a 50-60% hydrolyzate of tetramethoxysilane), (B) pref. a copolymer produced from 1-20 pts.wt. of hydroxy(meth)acrylate, 1-20 pts.wt. of a vinyl group-contg. hydrolyzable silyl compound, 10-70 pts.wt. of an acrylic ester and 10-50 pts.wt. of a methacrylic ester, (C) an organic solvent and (D) a curing catalyst (pref. an inorganic acid such as hydrochloric acid, an organotin compound such as dibutyltin laurate, etc.).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to coating compositions, and more particularly to scratch resistance, applied to the surface of iron, stainless steel, aluminum and other metals, plastics, wood, cement and other products. transparency,
The present invention relates to a coating composition having excellent heat resistance, weather resistance and adhesion.

[0002]

2. Description of the Related Art Hitherto, as a coating composition for improving scratch resistance, it has been disclosed in JP-A-53-2565.
JP-A-56-22365 and JP-A-61-1668.
There is a method using a hydrolyzate of an alkoxysilane described in Japanese Patent Laid-Open No. 24. In addition, as a coating composition containing organoalkoxysilane and colloidal silica or colloidal alumina as main components, Japanese Patent Publication No.
No. 39691, Japanese Patent Publication No. 53-5042, Japanese Patent Laid-Open No. 54
-87736, JP-A-55-94971, JP-A-5
6-99236, JP-A-59-68377, and the like.

Further, as a coating composition obtained by curing an acrylic copolymer containing an alkoxysilyl group, JP-A-3-47871 and JP-A-3-542 are disclosed.
No. 78 publication and the like can be mentioned. However, these coating compositions have drawbacks such as inferior scratch resistance of the resulting coating film, adhesion to a substrate, and storage stability of a solution.

[0004]

In view of the above circumstances, it is an object of the present invention to provide a coating composition excellent in scratch resistance, transparency, heat resistance, weather resistance and adhesion. .

[0005]

The present invention has been intensively studied to solve the above-mentioned problems.

[0006]

[Chemical 2]

(N is 1 to 20, R = CH ₃ , C
₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ or C ₆ H ₅ ), a silicate oligomer represented by (2) hydroxy (meth) acrylate and a vinyl group-containing hydrolyzable silyl compound, and / or an acrylate ester and / or A coating composition comprising a copolymer of methacrylic acid ester, (3) an organic solvent, and (4) a curing catalyst,
The inventors have found that the object can be achieved and arrived at the present invention.

The present invention will be described in detail below. Examples of the (1) silicate oligomer used in the present invention include 50-60% hydrolysis products of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraphenoxysilane and the like. The copolymer (2) used in the present invention is a copolymer of hydroxy (meth) acrylate, a vinyl group-containing silyl compound and an acrylic acid ester and / or a methacrylic acid ester.

Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, butyl methacrylate, lauryl methacrylate and the like. Examples of the acrylate ester include methyl acrylate, ethyl acrylate, butyl acrylate, and lauryl acrylate. Examples of hydroxy acrylate include 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate. Examples of hydroxymethacrylate include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 4-hydroxybutyl acrylate.

Examples of vinyl group-containing silyl compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and γ-methacryloxypropyltrimethoxysilane. The amount of the methacrylic acid ester used is 10 to 50 parts by weight,
The amount of the acrylate ester is 10 to 70 parts by weight, at least one kind selected from the group consisting of hydroxyacrylate or hydroxymethacrylate is 1 to 20 parts by weight, and the amount of the vinyl group-containing hydrolyzable silyl compound is 1 to 20 parts by weight. Part is desirable.

The above acrylic copolymer is optional as long as it is within the above composition range, but it is necessary to have a hydroxyl group in the acrylic copolymer as a condition to be compatible with the methyl silicate oligomer. In addition, the glass transition temperature of the acrylic copolymer is lowered to prevent problems such as cracking of the coating film due to curing shrinkage and internal stress when the coating film is formed after being hydrolyzed and coated with a silicate oligomer. Must be set.

The glass transition temperature of a desirable acrylic copolymer suitable for this purpose is -20 ° C to 40 ° C, and it is preferable to select the acrylic composition so as to fall within this range. Such a copolymer can be easily synthesized by ordinary radical polymerization. The organic solvent (3) that can be used varies depending on the material of the substrate to be coated, but for example, alcohols, glycol derivatives, hydrocarbons, esters, ketones, ethers may be used alone or in combination of two or more. Can be used.

Specific examples of alcohols include methanol, ethanol, isopropyl alcohol, n-butanol, isobutanol and octanol. Examples of glycol derivatives include ethylene glycol, ethylene glycol monomethyl ether, ethylene and glycol monoethyl ether. Examples thereof include ethylene glycol mono n-propyl ether and ethylene glycol mono n-butyl ether.

The hydrocarbons include benzene, kerosene,
Toluene, xylene, etc. can be used, and as esters,
Methyl acetate, ethyl acetate, butyl acetate, methyl acetoacetate, ethyl acetoacetate and the like can be used. Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and acetylacetone, and ethers such as ethyl ether, butyl ether, z-methyl cellosolve, ethyl cellosolve, dioxane, furan and tetrahydrofuran can be used.

The amount of the organic solvent used is preferably about 1 to 10 times the weight of the organic solvent-soluble resin in terms of operability. The curing catalyst (4) is, for example, hydrochloric acid,
Inorganic acids such as acetic acid, nitric acid, formic acid, sulfuric acid and phosphoric acid, organic acids such as paratoluene sulfonic acid, benzoic acid and phthalic acid,
Organotin compounds such as dibutyltin dilaurate, dibutyltin dioctiate and dibutyltin diacetate, and alkali catalysts such as potassium hydroxide and sodium hydroxide are effective, but inorganic acids, organic tin compounds and organic acids are particularly effective.

The amount of the organic solvent used is preferably about 1 to 10 times the weight of the copolymer composed of hydroxy (meth) acrylate and vinyl group-containing hydrolyzable silyl group in terms of operability. The amount of the silicate oligomer compounded is preferably 50 to 500 parts by weight with respect to 100 parts by weight of the copolymer composed of hydroxy (meth) acrylate and vinyl group-containing hydrolyzable silyl group. If it is 50 parts by weight or less, the hardness is lowered, which is not preferable, and if it is 500 parts by weight or more, the adhesion to the substrate is lowered, which is not preferable.

More specifically, this manufacturing method will be described.
Copolymer acrylic resin composed of hydroxy (meth) acrylate and vinyl group-containing hydrolyzable silyl group in organic solvent, and general formula

[0018]

[Chemical 3]

(N is 1 to 20, R = CH ₃ , C
₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ or C ₆ H ₅ ) is added, and an acid such as hydrochloric acid, dibutyltin laurate, or paratoluenesulfonic acid is added to carry out the hydrolysis reaction. There is a method. Further, as a substrate to which the coating composition of the present invention can be applied, iron, stainless steel, aluminum and other metals, plastic,
Examples include wood and cement.

The coating composition of the present invention can be applied by a coating means such as a brush, spin coating, spraying, dipping, roll, or gravure printing method. At this time, the film thickness of the formed film is usually about 0.1 to 200 μm, preferably about 0.1 to 100 μm. 0.1
If it is less than μm, sufficient scratch resistance cannot be obtained,
If it is thicker than m, the film is likely to be cracked. Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

[0021]

EXAMPLES In the following examples, all parts are parts by weight. [Synthesis of acrylic resin (I)] Using a 2000 ml separable flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer, 109 g of methyl methacrylate, 200 g of ethyl acrylate, and 200 g of ethyl acrylate were added to 900 g of tetrahydrofuran.
After adding 18.2 g of hydroxyethyl acrylate and 36.4 g of γ-methacryloxytrimethoxysilane, stirring was performed. After the temperature of the solution was raised to 65 ° C., 5 g of 2,2′-azobisisobutylnitrile was added to tetrahydrofuran 5
What was made to melt | dissolve in 0 g was dripped, and it stirred at 65 degreeC for 7 hours. After distilling off the tetrahydrofuran, it was dried to obtain an acrylic resin (I).

[Synthesis of acrylic resin (II)] Tetrahydrofuran 1200 was used using a 3000 ml separable flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer.
After adding 491 g of methyl methacrylate to g, stirring was performed. After the temperature of the solution was raised to 65 ° C., 7.5 g of 2,2′-azobisisobutylnitrile was added to tetrahydrofuran 7
What was dissolved in 5 g was added dropwise, and the mixture was stirred at 65 ° C. for 7 hours. After the tetrahydrofuran was distilled off, the residue was dried to obtain an acrylic resin (II).

[Synthesis of acrylic resin (III)] Tetrahydrofuran 120 was used using a 3000 ml separable flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer.
After 343 g of methyl methacrylate and 148 g of ethyl acrylate were added to 0 g, the mixture was stirred. After the temperature of the solution was raised to 65 ° C, a solution prepared by dissolving 7.5 g of 2,2'-azobisisobutylnitrile in 75 g of tetrahydrofuran was added dropwise, and the mixture was stirred at 65 ° C for 7 hours. After distilling off tetrahydrofuran, drying is performed to obtain an acrylic resin (II
I) got

Example 1 A 100 ml four-necked flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer was used.
5 g of acrylic resin (I) is added to 15 g of ethanol and dissolved at 65 ° C. To this, 5 g of "MS-51" (Mitsubishi Kasei product "MKC silicate MS51": product obtained by hydrolyzing 50% of tetramethoxysilane) is added. 0.95 g of 1N HCl is added to this solution and stirred at 65 ° C. for 30 minutes. This solution was added to SUS304 plate (70 mm × 150
(mm × 0.5 mm) was applied using a # 8 bar coater. The degree of scratches was evaluated by a pencil hardness test according to JIS K5400.

11 parallel and 11 vertical and horizontal lines perpendicular to the center of the coating film surface were drawn at intervals of 1 mm until reaching the substrate surface, and a grid was formed so that 100 squares could be formed in 1 cm ² . . Cellophane adhesive tape (Product name "Cellotape")
(Nichiban Co., Ltd. product) is strongly attached to the board, and
It was rapidly peeled in the direction of 0 degree, and the presence or absence of peeling of the coating film was examined. 100/10 when the number of films that did not peel off was examined
At 0, the adhesion was good.

The gloss of the coating film was measured at 60 ° specular gloss according to JIS-Z-8741. The heat resistance of the coating film is TG-DTA (TG / DTA20 manufactured by Seiko Instruments Inc.)
Measured at 10 ° C / min in a nitrogen atmosphere using a 5%
The temperature at which the weight loss occurs was used as a measure of heat resistance. The physical properties of this coating film are shown in Table 1.

Example 2 A 100 ml four-necked flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer was used.
5 g of the acrylic alcohol-soluble resin (I) is added to 15 g of ethanol and dissolved at 65 ° C. "MS-
51 "(Mitsubishi Kasei Product" MKC Silicate MS51 ":
Product obtained by hydrolyzing 50% of tetramethoxysilane) 10
g is added. 1.90 g of 1N HCl is added to this solution, and the mixture is stirred at 65 ° C. for 30 minutes. This solution was applied to a SUS304 plate (70 mm x 150 mm x 0.5 mm) using a # 8 bar coater. The coating film was evaluated in the same manner as in Example 1. The physical properties of this coating film are shown in Table 1.

Example 3 A coating film was formed and evaluated in the same manner as in Example 1 except that the SUS304 plate was changed to a PVC plate (100 mm × 100 mm × 2 mm).
The physical properties of this coating film are shown in Table 1. The total light transmittance and haze were measured according to JIS K-7105. (Substrate PVC plate 2 mm thick)

Example 4 A coating film was formed and evaluated in the same manner as in Example 1 except that the SUS304 plate was applied to the PMMA plate (100 mm × 100 mm × 2 mm).
The physical properties of this coating film are shown in Table 1. The total light transmittance and haze were measured according to JIS K-7105. (Base material PMMA plate thickness 2 mm)

[Example 5] A coating film was formed in the same manner as in Example 2 except that the SUS304 plate was changed to a PVC plate.
An evaluation was made. The physical properties of this coating film are shown in Table 1. The total light transmittance and haze were measured according to JIS K-7105. (Substrate PVC plate 2 mm thick)

[Example 6] A coating film was formed and evaluated in the same manner as in Example 2 except that the SUS304 plate was applied to the PMMA plate. The physical properties of this coating film are shown in Table 1.
The total light transmittance and haze are measured according to JIS K-710.
It measured based on 5. (Base material PMMA plate thickness 2 m
m)

Comparative Example 1 A 100 ml four-necked flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer was used.
5 g of acrylic resin (II) in 15 g of ethyl cellosolve
Add and dissolve at 65 ° C. To this, 5 g of "MS-51" (Mitsubishi Kasei product "MKC silicate MS51": product obtained by hydrolyzing 50% of tetramethoxysilane) is added.
0.95 g of 1N HCl is added to this solution and stirred at 65 ° C. for 30 minutes. This solution is SUS304 plate (70 mm x 1
50 mm × 0.5 mm) was coated with a # 8 bar coater, but the coating film became cloudy during coating and a good coating film could not be obtained.

Comparative Example 2 A 100 ml four-necked flask equipped with a nitrogen inlet tube, a reflux condenser and a stirring device was used.
5 g of acrylic resin (III) in 15 g of ethyl cellosolve
Add and dissolve at 65 ° C. To this, 5 g of "MS-51" (Mitsubishi Kasei product "MKC silicate MS51": product obtained by hydrolyzing 50% of tetramethoxysilane) is added.
0.95 g of 1N HCl is added to this solution and stirred at 65 ° C. for 30 minutes. This solution is SUS304 plate (70 mm x 1
50 mm × 0.5 mm) was coated with a # 8 bar coater, but the coating film became cloudy during coating and a good coating film could not be obtained.

[0034]

[Table 1]

[0035]

EFFECT OF THE INVENTION A coating composition having excellent scratch resistance, transparency, heat resistance, weather resistance and adhesion is obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area C09D 143: 04) 7921-4J

Claims (2)

[Claims] 1. A general formula: (N is 1 to 20, R = CH ₃ , C ₂ H ₅ , C ₃ H ₇ ,
A silicate oligomer represented by C ₄ H ₉ or C ₆ H ₅ ), (2) a hydroxy (meth) acrylate and a vinyl group-containing hydrolyzable silyl compound, and a copolymer of acrylic acid ester and / or methacrylic acid, (3 ) A coating composition comprising an organic solvent and (4) a curing catalyst. 2. The copolymer according to claim 1, wherein the copolymer of (2) is 10 to 50 parts by weight of at least one selected from the group consisting of methacrylic acid esters and at least 1 selected from the group consisting of acrylic acid esters. 1 to 20 parts by weight of at least one kind selected from the group consisting of 10 to 70 parts by weight of seeds and hydroxyacrylate or hydroxymethacrylate, and at least one kind of 1 to 20 selected from the group consisting of compounds containing a hydrolyzable silyl group. The coating composition according to claim 1, wherein the coating composition is produced from parts by weight.