JPH06212117A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain a coating composition excellent in scratch resistance, transparency, weather resistance and adhesion by mixing an alkoxysilane/hydroxy (meth)acrylate copolymer with an organic solvent and a curing catalyst. CONSTITUTION:The alkoxysilane (A) is a silicate oligomer represented by formula (wherein n is 1-20; and R is 1-6C linear or branched alkyl or aryl), the hydroxylated (meth)acrylate copolymer (B) comprises 80-99wt.% at least one (meth)acrylic ester and 1-20wt.% at least one hydroxylated (meth)acrylate component. Component A is used in an amount of 50-300 pts.wt. per 100 pts.wt. component B. The organic solvent is an alcohol, a hydrocarbon or the like or a mixture thereof. Its amount of use is about 1-10 times as large as that of component B. An effective curing catalyst is an inorganic acid, an organic acid, an organotin compound or the like. The thickness of the film is 0.1-50mum.

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 No. 24 and the like. In addition, as a coating composition containing organoalkoxysilane and colloidal silica or colloidal alumina as main components, Japanese Patent Publication No. 52-3
No. 9691, Japanese Patent Publication No. 53-5042, Japanese Patent Laid-Open No. 54-8.
7736, JP-A-55-94971, JP-A-56-
99236, JP-A-59-68377, and the like.

Further, as a coating composition obtained by curing an acrylic copolymer having an alkoxysilyl group, JP-A-3-47871 and JP-A-3-54278 are disclosed.
Etc. However, these coating compositions have drawbacks such as scratch resistance of the resulting coating film, adhesion to a substrate, and poor storage stability of the 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]

Means for Solving the Problems As a result of extensive studies to solve the above problems, it was found that the above objects can be achieved by using a combination of an alkoxysilane and a hydroxy (meth) acrylate copolymer. ,
The present invention has been reached. That is, the gist of the present invention is (1)
The coating composition comprises an alkoxysilane, a (2) hydroxy (meth) acrylate copolymer, (3) an organic solvent, and (4) a curing catalyst.

The present invention will be described in detail below. The alkoxysilane (1) used in the present invention is not particularly limited, but tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane,
Examples thereof include tetraphenoxysilane and the like, and hydrolysis products of 50 to 60% thereof.

A silicate oligomer represented by the following general formula (I) is preferably used.

[0008]

[Chemical 2]

(N represents an integer of 1 to 20. R represents a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group. Among R, CH ₃ and C ₂ are preferable.
H _5, C ₃ H _7, is _{C 4 H 9, C 6 H} 5. Although the method for producing these silicate oligomers is not particularly limited, for example, from a hydrolysis product of the above tetraalkoxysilane by a conventional method, a monomer component (n
It is preferable from the viewpoint of toxicity that the monomer component is not contained substantially by removing (= 0). In addition, storage stability is increased by reducing the amount of monomer components.

The hydroxy (meth) acrylate copolymer (2) used in the present invention is not particularly limited as long as it is an acrylic copolymer containing a hydroxy (meth) acrylate component, but it is a condition compatible with the silicate oligomer. Preferably, it is a copolymer of at least one selected from a hydroxy acrylate component and a hydroxy methacrylate component and at least one selected from a methacrylic acid ester component and an acrylic acid ester component.

The hydroxy acrylates which give the hydroxy acrylate component include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 4
-Hydroxybutyl acrylate and the like can be mentioned. As hydroxymethacrylate that gives a hydroxymethacrylate component, 2-hydroxyethylmethacrylate, 2-hydroxypropylmethacrylate, 4-hydroxymethacrylate
Examples thereof include hydroxybutyl methacrylate.

Further, as the methacrylic acid ester which gives the methacrylic acid ester component, methyl methacrylate,
Examples thereof include ethyl methacrylate, butyl methacrylate, lauryl methacrylate and the like. Examples of the acrylate ester that provides the acrylate component include methyl acrylate, ethyl acrylate, butyl acrylate, and lauryl acrylate.

The hydroxyacrylate component and / or hydroxymethacrylate component is preferably 1 to 20% by weight, and the methacrylic acid ester component and / or acrylic acid ester component is preferably 80 to 99% by weight in the copolymer. If the hydroxyacrylate component or hydroxymethacrylate component is less than 1% by weight, the transparency is poor, and
If it exceeds 5% by weight, the hardness is lowered and the scratch resistance is deteriorated, which is not preferable.

The methacrylic acid ester component and the acrylic acid ester component may be used alone, but are preferably used in combination. When used in combination, the ratio of the methacrylic acid ester component to the acrylic acid ester component is such that the methacrylic acid ester component: acrylic acid ester component = 2: 1 to 1:
5, preferably 1: 1 to 1: 3, particularly preferably about 1:
2 (weight ratio). Further, after the coating composition of the present invention is hydrolyzed and coated, when a coating film is formed, the glass of the copolymer is used in order to prevent curing shrinkage and internal stress, which causes problems such as cracking of the coating film. It is necessary to set the transition temperature low.

A desirable glass transition temperature for this purpose is -20 ° C to 40 ° C, and it is necessary to select an acrylic composition so as to fall within this range. Such a copolymer can be easily synthesized by an ordinary radical polymerization method. 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, or a mixture of two or more thereof. Can be used.

Specific examples of alcohols include methanol, ethanol, isopropyl alcohol, n-butanol, isobutanol, and octanol, and examples of glycol derivatives include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene. Examples thereof include 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 hydroxy (meth) acrylate resin in terms of operability. Examples of the curing catalyst (4) include inorganic acids such as hydrochloric acid, acetic acid, nitric acid, formic acid, sulfuric acid and phosphoric acid, organic acids such as paratoluenesulfonic acid, benzoic acid and phthalic acid, dibutyltin dilaurylate and dibutyltin. Organic tin compounds such as dioctyate and dibutyltin diacetate are effective, and alkali catalysts such as potassium hydroxide and sodium hydroxide are effective, but inorganic acids, organic tin compounds, organic titanate compounds, organic aluminum compounds and organic acids are particularly effective. Is.

The amount of the alkoxysilane compounded is preferably 50 to 300 parts by weight, more preferably 10 parts by weight, based on 100 parts by weight of the hydroxy (meth) acrylate copolymer resin.
0 to 250 parts by weight. If it is 50 parts by weight or less, the hardness is lowered, which is not preferable, and if it is 300 parts by weight or more, the adhesiveness to the substrate is lowered, which is not preferable. More specifically, the production method will be described by adding an organic solvent hydroxy (meth) acrylate resin, and an alkoxysilane, preferably a silicate oligomer represented by the general formula (I), and adding hydrochloric acid, dibutyltin dilaurylate, para. A method of adding an acid such as toluenesulfonic acid to carry out the hydrolysis reaction can be mentioned.

Substrates to which the coating composition of the present invention can be applied include iron, stainless steel, aluminum and other metals, plastic, wood, cement and the like. The coating composition of the present invention can be applied by a coating means such as brush, spin coating, spraying, dipping, roll, and gravure printing method. At this time, the film thickness of the coating film formed is usually about 0.1 to 50 μm, preferably about 0.1 to 20 μm. If it is less than 0.1 μm, sufficient scratch resistance cannot be obtained, and if it is more than 50 μm, the film is likely to be cracked.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. In the following examples, all "parts" are "parts by weight".

(1) Synthesis of acrylic resin (I) 3000 equipped with a nitrogen inlet tube, a reflux condenser and a stirrer
Using a ml separable flask, 164 g of methyl methacrylate, 300 g of ethyl acrylate, and 27 g of 2-hydroxyethyl acrylate were added to 1200 g of tetrahydrofuran, followed by stirring. After the temperature of the solution was raised to 65 ° C., 2,2′-azobisisobutylnitrile 7.5
What melt | dissolved g in tetrahydrofuran 75g 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).

(2) Synthesis of acrylic resin (II) 3000 equipped with a nitrogen inlet tube, a reflux condenser and a stirrer
Using a ml separable flask, 491 g of methyl methacrylate was added to 1200 g of tetrahydrofuran, followed by stirring. After heating the solution to 65 ° C,
What melt | dissolved 7.5 g of 2'-azobisisobutyl nitrile in 75 g of tetrahydrofuran was dripped, and it was 65 degreeC.
The mixture was stirred for 7 hours. After the tetrahydrofuran was distilled off, the residue was dried to obtain an acrylic resin (II).

(3) Synthesis of acrylic resin (III) 3000 equipped with a nitrogen introducing pipe, a reflux condenser and a stirring device
Using a ml separable flask, 343 g of methyl methacrylate and 148 g of ethyl acrylate were added to 1200 g of tetrahydrofuran, followed by stirring. 6 solution
After heating to 5 ° 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 the tetrahydrofuran was distilled off, the residue was dried to obtain an acrylic resin (III).

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 the acrylic resin (I) was added to 15 g of ethanol and dissolved at 65 ° C. To this was added 5 g of MS-51 (trade name "MKC silicate MS51" manufactured by Mitsubishi Kasei Co., Ltd .: a product obtained by hydrolyzing 50% of tetramethoxysilane) (substantially containing no monomer component). 0.95 g of 1N HCl was added to this solution, and the mixture was stirred at 65 ° C. for 30 minutes. This solution is SUS304 plate (stainless steel: 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 . A cellophane adhesive tape (trade name "Cellotape" manufactured by Nichiban Co., Ltd.) was strongly adhered to the cross-cut and rapidly peeled in the direction of 90 degrees to examine the presence or absence of peeling of the coating film. The number of cells in which peeling of the coating film did not occur was examined and the closeness was evaluated.

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 resin (I) was added to 15 g of ethanol and dissolved at 65 ° C. To this, 10 g of MS-51 was added. 1.90 g of 1N HCl was added to this solution, and the mixture was stirred at 65 ° C. for 30 minutes. This solution is SUS304 plate (70m
m × 150 mm × 0.5 mm) using a # 8 bar coater. This 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 x 100 mm x thickness 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.

<Example 4> A coating film was formed and evaluated in the same manner as in Example 1 except that the SUS304 plate was changed to a PMMA plate (100 mm x 100 mm x thickness 2 mm). The physical properties of this coating film are shown in Table 1.

<Example 5> A coating film was formed and evaluated in the same manner as in Example 2 except that the SUS304 plate was changed to a PVC plate (thickness: 2 mm). The physical properties of this coating film are shown in Table 1.
It was shown to.

<Example 6> A coating film was formed and evaluated in the same manner as in Example 2 except that the SUS304 plate was changed to a PMMA plate (thickness: 2 mm). The physical properties of this coating film are shown in Table 1.
It was shown to.

Example 7 A 100 ml four-necked flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer was used.
10 g of the acrylic alcohol-soluble resin (I) is added to 15 g of ethanol and dissolved at 65 ° C. MS-
5 g of 51 (Mitsubishi Kasei product "MKC silicate MS51": product obtained by hydrolyzing 50% of tetramethoxysilane) is added. To this solution, 0.95 g of 1N HCl was added and 65
Stir for 30 minutes at ° C. This solution was added to SUS304 plate (7
0 mm × 150 mm × 0.5 mm) was coated using a # 8 bar coater. This coating film was evaluated in the same manner as in Example 1, and the physical properties of this coating film are shown in Table 1.

<Example 8> 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-5
15 g of 1 (Mitsubishi Chemical's product "MKC silicate MS51": a product obtained by hydrolyzing 50% of tetramethoxysilane) is added. 2.85 g of 1N HCl was added to this solution, and 65
Stir for 30 minutes at ° C. This solution was added to SUS304 plate (7
0 mm × 150 mm × 0.5 mm) was coated using a # 8 bar coater. This coating film was evaluated in the same manner as in Example 1, and the physical properties of this coating film are shown in Table 1.

<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
The mixture was added and dissolved at 65 ° C. To this, 5 g of MS-51 was added. 0.95 g of 1N HCl was added to this solution at 65 ° C.
And stirred for 30 minutes. This solution was added to SUS304 plate (70
(mm × 150 mm × 0.5 mm) was applied using 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 stirrer was used.
5 g of acrylic resin (III) in 15 g of ethyl cellosolve
The mixture was added and dissolved at 65 ° C. To this, 5 g of MS-51 was added. 0.95 g of 1N HCl was added to this solution, and the mixture was stirred at 65 ° C. for 30 minutes. This solution is SUS304 plate (70m
m × 150 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 3> 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) in 15 g of ethyl alcohol
The mixture was added and dissolved at 65 ° C. To this, 20 g of MS-51
Was added. To this solution was added 3.8 g of 1N HCl, and 65
The mixture was stirred at 0 ° C for 30 minutes. This solution was added to SUS304 plate (7
(0 mm × 150 mm × 0.5 mm) was applied using a # 8 bar coater, but when the cellophane tape was peeled off, the adhesion was 0/100 and the adhesion was poor.

[0038]

[Table 1]

[0039]

The coating composition of the present invention is excellent in scratch resistance, transparency, heat resistance, weather resistance and adhesion.
It can be applied to metals such as iron and stainless steel, and surfaces such as plastic and wood.

Claims (4)

[Claims] 1. A coating composition containing (1) an alkoxysilane, (2) a hydroxy (meth) acrylate copolymer, (3) an organic solvent, and (4) a curing catalyst. 2. The coating composition according to claim 1, wherein (1) the alkoxysilane is a silicate oligomer represented by the following general formula (I). [Chemical 1] (N represents an integer of 1 to 20. R represents a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group.) 3. A hydroxy (meth) acrylate copolymer (2) is at least 80% to 99% by weight of at least one selected from (a) a methacrylic acid ester component and an acrylic acid ester component.
And (b) at least one or two selected from a hydroxy acrylate component and a hydroxy methacrylate component.
0% by weight, characterized in that
The coating composition described. 4. The (1) alkoxysilane is 50 to 300 parts by weight with respect to 100 parts by weight of the (2) hydroxy (meth) acrylate copolymer.
4. The coating composition according to any one of 3 to 3.