JPH0830169B2 - Coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coating composition, and more specifically, it forms a firm film on the surface of stainless steel, aluminum, cement, wood, paper, glass, plastic, etc. , Adhesion, weather resistance, heat resistance, water resistance, corrosion resistance, abrasion resistance, flame resistance, moisture resistance, water permeability, chemical resistance, acid resistance, especially alkali resistance, etc. And a coating composition suitable for providing such as.

[Conventional technology]

In recent years, even with a film thickness of 50 μm or less, pinhole-free adhesion, weather resistance, heat resistance, water resistance, corrosion resistance, wear resistance,
There is a demand for a coating composition that is excellent in flame resistance, moisture resistance, water permeability resistance, chemical resistance, acid resistance, particularly alkali resistance and can form a coating film having high hardness.

An acidic aqueous composition containing a partial condensate of silanol and colloidal silica has been proposed as a coating composition that satisfies some of these requirements (Japanese Patent Publication No. 52-52).
-39691 publication).

[Problems to be solved by the invention]

However, the coating composition described in JP-B-52-39691 is a lower alcohol containing a partial condensate of silanol containing monomethyltrisilanol as a main component-dispersing colloidal silica in an aqueous solution to adjust pH. However, the partial condensation of silanol does not proceed sufficiently, and even if a coating film is formed using this composition, the adhesion of the coating film to the substrate is not sufficient. Since the siloxane bond of the coating film is hydrolyzed under alkaline conditions, it has a drawback that it is inferior in alkali resistance.

The present invention has been made against the background of the above-mentioned conventional technical problems, and adhesion, weather resistance, heat resistance, water resistance, corrosion resistance, abrasion resistance, flame resistance, humidity resistance, water permeability, chemical resistance. , Acid resistance,
In particular, it is an object of the present invention to provide a coating composition having excellent alkali resistance and capable of forming a coating film having high hardness that can be used for applications such as corrosion prevention and insulation.

[Means for solving problems]

That is, the present invention provides (a) general formula (I) CH ₃ Si (OR) ₃ ... (I) [wherein, R represents a lower alkyl group. ] 10-90% by weight of methyltrialkoxysilane represented by
And general formula (II) [In the formula, R ′ represents a lower alkylene group and R represents the same meaning as described above. ] 100 parts by weight of a co-hydrolyzate and / or a partial co-condensate of an organoalkoxysilane consisting of 90 to 10% by weight of a γ-glycidoxyalkyltrialkoxysilane represented by: A coating composition comprising 10 to 200 parts by weight, (c) 100 to 600 parts by weight of a hydrophilic organic solvent, and (d) 1 to 50 parts by weight of polyamines. .

Hereinafter, each component constituting the composition of the present invention will be described.

First, the component (a) is represented by the general formula (I) and the general formula (II).
Is a co-hydrolyzate and / or partial co-condensate of two types of organoalkoxysilanes represented by the following formula, and when the composition is applied to a substrate and heated, it is further polycondensed to have a high molecular weight and glycidyl. The group is a group which is polymerized and cured by the catalytic action of the component (d) and functions as a binder in the composition obtained in the present invention.

R in the general formulas (I) and (II) is a lower alkyl group, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group,
Examples thereof include a t-butyl group, and among these, a methyl group and an ethyl group are preferable.

R'in the general formula (II) is a lower alkylene group such as methylene group, ethylene group, propylene group,
Examples thereof include a butylene group, and among these, an ethylene group and a propylene group are preferable.

Specific examples of the methyltrialkoxysilane represented by the general formula (I) include methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-propoxysilane, methyltri-i-propoxysilane, methyltri-n-butoxysilane and methyltriethoxysilane. Examples thereof include -i-butoxysilane, and among these, methyltrimethoxysilane and methyltriethoxysilane are preferable.

Moreover, specific examples of the γ-glycidoxyalkyltrialkoxysilane represented by the general formula (II) include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-glycidoxy. Ethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltri-n-
Propoxysilane, γ-glycidoxypropyltri-n
-Butoxysilane, δ-glycidoxybutyltrimethoxysilane, and the like. Among these, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane. And γ-glycidoxypropyltriethoxysilane are preferred.

These organoalkoxysilanes may be used alone or in combination of two or more.

The polystyrene-reduced weight average molecular weight of the cohydrolyzate and partial cocondensate of such an organoalkoxysilane is preferably 400 to 30,000, particularly preferably 800 to 100.
If it is less than 400, sagging or repellency may occur during application, and a uniform coating film may not be formed.
If it exceeds 00, storage stability may deteriorate and gelation may occur, or the hardness of the cured coating film may decrease with time, which is not preferable.

The proportion (% by weight) of (I) methyltrialkoxysilane and (II) γ-glycidoxyalkyltrialkoxysilane in the cohydrolyzate and partial cocondensate of organoalkoxysilane is 10 to 90/90. ~ 10, preferably 15-8
It is 0/85 to 20, more preferably 40 to 70/60 to 30. (II
If the proportion of I) γ-glycidoxyalkyltrialkoxysilane is less than 10% by weight, the alkali resistance of the cured coating film is inferior, and if it exceeds 90% by weight, heat resistance and hardness decrease, which is not preferable.

Next, the component (b) is used for increasing the solid content of the composition of the present invention, and the thickness of the coating film can be adjusted by the amount thereof. The colloidal silica used as the component (b) usually has an average particle size of 5 to 30.
It is an aqueous dispersion or alcohol dispersion containing 10 to 40% by weight, preferably 15 to 35% by weight, as a solid content of high-purity silicic anhydride of mμ, preferably 10 to 20 mμ.

The colloidal silica containing water as a dispersion medium is usually in an acidic region, preferably pH 2-6, more preferably 2-5. Colloidal silica in this acidic region generally has a low sodium content among commercially available colloidal silica, and since it is in the acidic region, the coating film can be cured after the composition is applied. Sodium contained in colloidal silica is a negative factor for the acid corrosion resistance and electrical insulation of the resulting coating film, so the less the colloidal silica loses its stability as a colloid, the lower the limit. Preferably, the content is usually about 0.05% by weight or less.

Examples of the colloidal silica in the acidic region using water as the dispersion medium include, for example, Nissan Chemical Industry Co., Ltd., Snowtex; Catalytic Chemical Industry Co., Ltd., Cataloid; USA Deyupon, Ludox, USA Monsanto. , Syton; Nalcoag manufactured by Nalco Chemical Company of the United States and the like can be mentioned.

Colloidal silica having alcohol as a dispersion medium is also commercially available, and examples thereof include Nissan Chemical Industry Co., Ltd., methanol silica sol, isopropanol silica sol; Catalyst Kasei Kogyo Co., Ltd., and Oscar.
The colloidal silica may be used in combination.

The proportion of the component (b) in the composition is 10% of the component (a).
With respect to 0 parts by weight, it is 10 to 200 parts by weight, preferably 20 to 150 parts by weight in terms of solid content, and if it is less than 10 parts by weight, it is difficult to achieve thickening of the obtained coating film, while 200 parts by weight is used. If it exceeds, cracks are likely to occur in the resulting coating film, which is not preferable.

Next, the component (c) is used as a stabilizer for the composition of the present invention, and suppresses the hydrolysis of the component (a) to cause gelation, and also the total solid content concentration of the composition. It acts as a diluent for adjusting the.

As the component (c), alcohols and / or glycol derivatives are suitable.

Examples of such alcohols and / or glycol derivatives include ethylene glycol which is a monohydric alcohol or a dihydric alcohol or a derivative thereof. Among them, the monohydric alcohol has 1 to 10 carbon atoms.
8 aliphatic alcohols are preferable, and specifically, methanol, ethanol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-pentyl alcohol, n-hexyl alcohol. Examples of the ethylene glycol or its derivative include ethylene glycol, ethylene glycol monobutyl ether, and ethylene glycol monoethyl ether acetate.

Of these alcohols and / or glycol derivatives, methanol, ethanol, n-propyl alcohol, i-propyl alcohol, sec-butyl alcohol, n-butyl alcohol, ethylene glycol monoethyl ether acetate and ethylene glycol monobutyl ether are preferable.

These hydrophilic organic solvents may be used alone or in combination of 2
It is also possible to use two or more species together.

The ratio of the component (c) in the composition is 100 to 600 parts by weight, preferably 150 to 400 parts by weight, relative to 100 parts by weight of the component (a), and the ratio of the component (c) exceeds 600 parts by weight. When the total solid content of the composition is too low, swelling or blistering occurs during coating film formation, pinholes are formed in the resulting coating film, and further heat resistance, water resistance, chemical resistance, and electrical resistance of the coating film. If the ratio of the component (c) is less than 100 parts by weight, the total solid content concentration of the composition is too high and the storage stability of the composition deteriorates, causing gelation. It is not preferable because it is difficult to obtain a uniform coating film.

The component (c) in the composition of the present invention is
It contains a hydrophilic organic solvent which may be present in the component (b).

The component (d) polymerizes the glycidyl group in the component (a) and functions as a curing agent for the coating film in the composition obtained by the present invention. Examples of such polyamines include ethylenediamine, diethylenetriamine, triethylenetriamine, tetraethylenepentamine, diethylaminopropylamine, m-phenylenediamine, p-phenylenediamine, p, p'-diaminodiphenylmethane, diaminodiphenylmethane. Examples thereof include enyl sulphate and modified polyamines represented by the following general formula.

_{H 2 N-R 2 -NHCH 2} CH 2 CN, NCCH 2 CH 2 NH-R 2 -NHCH 2 CH 2 CN wherein, R ₁ represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, R ₂ is means _{-CH 2 CH 2 NHCH 2 CH 2} n, and n is 0
~ 3 is shown. ] Of these polyamines, ethylenediamine, p
Phenylenediamine and p, p'-diaminodiphenylmethane are preferred.

Incidentally, conventionally known amines, acid anhydrides and aromatic polycarboxylic acids can be used as the curing agent instead of the component (d), but when polyamines are used as in the present invention, As compared with the case where other curing agents are used, the coating film can be cured under relatively mild conditions, and the hardness of the obtained coating film is excellent.

Further, the above-mentioned polyamines can be used in combination with conventionally known amines.

The ratio of the component (d) in the composition is 1 to 50 parts by weight, preferably 3 to 30 parts by weight, relative to 100 parts by weight of the component (a). Insufficient polymerization of glycidyl groups and curing of the coating film reduces the alkali resistance, and when it exceeds 50 parts by weight, the coating film becomes colored and the organic components in the resulting coating film relatively increase, resulting in heat resistance. It is not preferable because it deteriorates the property.

As described above, the coating composition of the present invention contains the components (a) to (d), and the total solid content concentration thereof is preferably 5 to 45% by weight, and more preferably 8%.
If the content is less than 5% by weight, the solid content may be too thin, and thus various properties such as heat resistance, water resistance, chemical resistance, and weather resistance of the resulting coating film may not be exhibited. There may be pinholes in the coating film. On the other hand, if it exceeds 45% by weight, the solid content concentration may be too high, and the storage stability of the composition may be deteriorated, and it may be difficult to form a uniform coating film.

Furthermore, various pigments, dyes, surfactants, fillers, curing agents other than the above, and the like can be added to the composition of the present invention.

The coating composition of the present invention is usually (a),
It is produced by preparing a mixed solution comprising the components (b) and (c) and having excellent storage stability, and adding the polyamines (d) before coating. For example, the general formula (I)
And a general formula (I
The mixture with the γ-glycidoxyalkyltrialkoxysilane represented by I) is added in the presence of colloidal silica and a hydrophilic organic solvent in the temperature range of room temperature to 80 ° C.
After hydrolysis and polycondensation for 8 hours, (a), (b)
It can be manufactured by obtaining a mixed solution of (c) and (c) and then mixing (d) before coating. When colloidal silica having alcohol as a dispersion medium is used as the component (b), water is usually added to the mixture (I) methyltrialkoxysilane and (II) γ-glycidoxyalkyltrialkoxysilane. 0.5 to 6 mol per 1 mol in total.

The coating composition of the present invention thus obtained is a coating, a spray, a dipping, a spin cord on the surface of a base material such as stainless steel, aluminum, cement, wood, paper, glass or plastic which is an object of coating. With such a coating means, a coating film having a thickness of about 1 to 20 μm can be formed by converting the film thickness when dried by one coating.

A firm coating film can be obtained by applying the coating so as to have a predetermined film thickness, immediately or naturally drying it, and then heating and drying at 80 to 300 ° C. for 10 to 60 minutes to cure.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to the present invention, but the present invention is not limited to the following examples.

In the following examples, parts and% are based on weight unless otherwise specified.

Examples 1 to 5 and Comparative Examples 1 to 7 An organoalkoxysilane consisting of methyltrialkoxysilane and γ-glycidoxyalkyltrialkoxysilane at a ratio shown in Table 1 in a container equipped with a reflux condenser and a stirrer ( a) ′, colloidal silica (b), hydrophilic organic solvent (c), and water if necessary, at 70 ° C.
Heated to room temperature and reacted for 4 hours to give a cohydrolyzate and / or partial cocondensate (a) of an organoalkoxysilane.
Mixture A of colloidal silica and hydrophilic organic solvent
E and FL were prepared respectively. This mixture AE
Table 1 shows the storage stability of FL and FL. Furthermore, the coating compositions a to e were prepared by adding the polyamines (d) to the mixtures A to E and FL in the proportions shown in Table 2.
And fl were obtained. Then, the obtained compositions a to e and f to l were treated with a degreasing agent for aluminum (PS-500A, Koei Kogyo Co., Ltd.).
Made in a 5% aqueous solution at room temperature for 1 hour, washed with water, dried and alkali degreased aluminum plate (JIS H400
0, A2024P) was spray-coated and heated at 150 ° C. for 30 minutes to form a cured coating film. The obtained cured coating film was tested for hardness, adhesion, heat resistance, acid resistance and alkali resistance. The results are shown in Table 2. The test shown in Table 2 was conducted according to the following.

Hardness: Measured by the pencil hardness method according to JIS K5400.

Adhesion: A tape peeling test was performed after a 1 mm square cross-cut test according to JIS K5400 to measure the remaining amount.

Heat resistance: It was kept at 200 ° C. for 240 hours in an electric furnace, and the state of the coating film after spontaneous cooling was observed.

Heat resistance: It was kept at 400 ° C. for 240 hours in an electric furnace, and the state of the coating film after spontaneous cooling was observed.

Acid resistance: 1 ml of hydrochloric acid having a concentration of 20% was dropped on the surface of the coating film, and the mixture was allowed to stand in a dish with a lid for 1 day and washed with water to observe the state of the coating film.

Acid resistance: 1 ml of 20% concentration sulfuric acid was dropped on the surface of the coating film, and the mixture was allowed to stand in a dish with a lid for 1 day, washed with water, and the state of the coating film was observed.

Alkali resistance: 1 ml of a 1% concentration aqueous sodium hydroxide solution was dripped on the surface of the coating film, allowed to stand for 1 day in a dish with a lid, and washed with water to observe the state of the coating film.

Alkali resistance: A 1% aqueous solution of sodium hydroxide having a concentration of 3% was dripped on the surface of the coating film, allowed to stand still for 1 day in a dish with a lid, and then washed with water to observe the state of the coating film.

Comparative Example 8 A cured coating film was formed in the same manner as in Example 1 except that 6 parts by weight of n-butylamine was used instead of 5 parts by weight of ethylenediamine, and the properties such as hardness were tested (the test method was also described in Example 1).
Same as). The results were as follows.

Hardness: 2H, Adhesion: 100/100, Heat resistance: No change, Heat resistance: No change, Acid resistance: No change, Acid resistance: No change, Alkali resistance: Luster to the coating film, Alkali resistance: Melt coating film.

As shown in the above results, the hardness and alkali resistance are low when the monoamine is used. On the other hand, in the present application, a strong coating film (particularly hardness and alkali resistance) could be obtained by using polyamine as a curing catalyst.

[Effects of the Invention] The composition of the present invention is usually blended with polyamines before use, but the mixed solution before addition of the polyamines exhibits stability at room temperature for 6 months or more. The coating film obtained by subjecting the product to coating is sufficiently cured by heating for a short time, can be overcoated to obtain an arbitrary film thickness, does not cause pinholes even in a thin film of about 20 μm, and is made of stainless steel. It can be used for various base materials such as aluminum, cement, wood, paper, glass, plastic, etc., adhesion, weather resistance, heat resistance, water resistance, corrosion resistance, abrasion resistance, flame resistance, moisture resistance, It has features such as excellent water resistance, chemical resistance, acid resistance, especially alkali resistance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshinori Yoshida Inventor Yoshinori Yoshida, 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Nippon Synthetic Rubber Co., Ltd. (56) Reference JP-A-57-140162 (JP, A) Kai 57-182363 (JP, A)

Claims (1)

[Claims] 1. (a) General formula (I) CH ₃ Si (OR) ₃ (I) [In the formula, R represents a lower alkyl group. ] 10-90% by weight of methyltrialkoxysilane represented by
And general formula (II) [In the formula, R ′ represents a lower alkylene group and R represents the same meaning as described above. ] 100 parts by weight of a co-hydrolyzate and / or a partial co-condensate of an organoalkoxysilane consisting of 90 to 10% by weight of a γ-glycidoxyalkyltrialkoxysilane represented by: A coating composition containing 10 to 200 parts by weight, (c) 100 to 600 parts by weight of a hydrophilic organic solvent, and (d) 1 to 50 parts by weight of polyamines.