JPH08176509A - Resin composition for coating - Google Patents

Abstract

PURPOSE: To obtain a coating resin composition having excellent storage stability as well as coating film properties. CONSTITUTION: This resin composition for coating is produced by adding (A) a polybasic carboxylic acid to (B) a silicone resin containing silanol group, expressed by the general formula Rb Si(OH)c (OR')d O(4-b-c-d)/2 (R groups are the same or mutually different substituted or unsubstituted univalent hydrocarbon groups; R' is a 1-10C substituted or unsubstituted univalent hydrocarbon group; 0.8<=b<=2; 0.04<=c<=1; 0<=d<=0.5; O.9<=b+c+d<=3) and obtained by the hydrolytic condensation of a silane expressed by the general formula Ra SiX4-a (R groups are the same or different substituted or unsubstituted univalent hydrocarbon groups; (a) is 0, 1 or 2; X is an alkoxy group or a halogen atom) or its partial hydrolytic condensation product. The addition amount of the component A is 1-10,000ppm based on the component B.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coating resin composition, and more particularly to a coating resin composition comprising a silanol group-containing silicone resin having excellent stability.

[0002]

2. Description of the Related Art Conventionally, silanol group-containing silicone resins have been used as paint resins because of their excellent heat resistance, solvent resistance, adhesion and the like (hereinafter referred to as coating film physical properties).
Further, in order to further improve the physical properties of the coating film, a silanol group-containing silicone resin having a methyl group or a phenyl group introduced into its side chain has been developed.

However, in such a silanol group-containing silicone resin, when the content of the silanol group is increased to improve the physical properties of the coating film, the silanol groups undergo a condensation reaction due to the high activity of the silanol group, resulting in a high molecular weight. It turns into a gel. Therefore, there is a drawback that the storage stability (simply referred to as storage stability) of the paint is deteriorated. In addition, the silanol group-containing silicone resin,
Fillers, pigments, etc. are added to form a paint, and these fillers, pigments, etc. include alkali such as barium oxide,
Since metal compounds such as aluminum powder are contained as impurities, they act as a catalyst and have a drawback that storage stability is deteriorated.

[0004]

Therefore, as a result of diligent studies to solve the above-mentioned drawbacks, the present inventors have found that when a specific amount of a polycarboxylic acid is added to a silanol group-containing silicone resin, the coating While maintaining good film properties,
The inventors have found that the condensation reaction between silanol groups can be prevented and the storage stability of the coating can be improved, and the present invention has been reached. Therefore, the object of the present invention is to
It is an object of the present invention to provide a resin composition for a coating which is excellent not only in physical properties of a coating film but also in storage stability.

[0005]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
A general formula R _b obtained by hydrolytically condensing a silane represented by the general formula R _a SiX _4-a or a partial hydrolysis-condensation product thereof.
A resin composition for coating, comprising a silanol group-containing silicone resin (A) represented by Si (OH) _c (OR ′) _d O _{(4-bcd) / 2} , and a polycarboxylic acid (B) added thereto. ,
The amount of (B) added is 1 ppm to 10,000 relative to (A).
Achieved by a coating resin composition characterized by 0 ppm.

In the above general formula R _a SiX _4-a , R is the same or different and is a substituted or unsubstituted monovalent hydrocarbon group, and a is either 0, 1 or 2. , X is an alkoxy group or a halogen atom. The general formula R _b S
In i (OH) _c (OR ′) _d O _{(4-bcd) / 2} , R is the same or different and is a substituted or unsubstituted monovalent hydrocarbon group, and R ′ is carbon. It is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 atoms. b, c and d are
0.8 ≦ b ≦ 2, 0.04 ≦ c ≦ 1, 0 ≦ d ≦ 0.5,
In addition, it is a number that satisfies 0.9 ≦ b + c + d ≦ 3.

Specific examples of the substituted or unsubstituted monovalent hydrocarbon group represented by R include alkyl groups such as methyl group, ethyl group, propyl group, butyl group and hexyl group, and cyclo groups such as cyclohexyl group. Alkyl groups, vinyl groups, alkenyl groups such as allyl groups, aryl groups such as phenyl groups and tolyl groups, or chloromethyl groups and trifluoropropyl groups in which some or all of the hydrogen atoms of these groups are replaced with halogen atoms. And a cyanomethyl group substituted with a cyano group. Among these, it is particularly preferable that R is a methyl group or a phenyl group from the viewpoint of industrial production.

R'in the general formula has 1 to 10 carbon atoms.
A substituted or unsubstituted monovalent hydrocarbon group of
The number of carbon atoms is preferably 1 to 7. Specific examples of such a monovalent hydrocarbon group include an alkyl group, an aryl group, an aralkyl group, a cycloalkyl group, or a part or all of the hydrogen atoms of these groups substituted with a halogen atom or a cyano group. A group etc. can be mentioned.
The alkoxy group represented by OR ′ in the above general formula is the following when X in the general formula R _a SiX _4-a is an alkoxy group:
It is an alkoxy group which remains after hydrolysis, and when X is a halogen atom, it is an alkoxy group which is generated by reaction with the alcohol used as a solvent during hydrolysis and remains in the resin.

Specific examples of the hydrolyzable silane represented by the above general formula R _a SiX _4-a or its partial hydrolytic condensate are tetrachlorosilane, methyltrichlorosilane,
Dimethyldichlorosilane, phenyltrichlorosilane,
Chlorosilanes such as diphenyltrichlorosilane, phenylmethyldichlorosilane, trifluoropropyltrichlorosilane, trifluoropropylmethyldichlorosilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, phenyltrimethoxysilane, phenyl Triethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenylmethyldimethoxysilane,
Examples thereof include alkoxysilanes such as phenylmethyldiethoxysilane and partial hydrolysates thereof.
In the present invention, two or more of these may be used in combination.

The above-mentioned silane or a partial hydrolysis-condensation product thereof is hydrolyzed and condensed to give a compound of the general formula R _b Si (OH) 2.
_Obtaining a silanol group-containing silicone resin (A) represented by _c (OR ′) _d O _{(4-bcd) / 2} (hereinafter, simply referred to as silanol group-containing silicone resin) is disclosed in, for example, JP-A-4-180926. It can be easily performed using the method described in the publication. That is, it is a method of hydrolyzing and condensing silane or a partial hydrolyzate thereof with water and a catalyst with stirring. As the above catalyst,
Acids such as hydrochloric acid, sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid, etc., hydroxides of alkali metals or alkaline earth metals such as NaOH, KOH, Ca (OH) ₂ , alkaline organic compounds such as triethylamine, tetraethylammonium hydroxide, etc. There are substances, etc. When chlorosilanes are used, hydrochloric acid produced as a by-product acts as a catalyst.

The temperature and reaction time of the hydrolysis condensation reaction are
It may be appropriately determined according to the characteristics of the raw material used and the required product, but it is usually 10 to 150 ° C. and 1 to 29 hours. In the reaction, a solvent may be used if necessary. Solvents that can be used include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane and octane, methanol, ethanol, 2
-Alcohols such as propanol and ketones such as acetone and methyl ethyl ketone.

After the reaction, the silanol group-containing silicone resin is quenched by adding an alkali or an acid to neutralize the reaction, and then washing with water, filtering, distilling under atmospheric pressure or distilling under reduced pressure as a by-product. It can be obtained by removing the solvent or the like. The average molecular weight of the obtained silanol group-containing silicone resin is usually in the range of 500 to 20,000, preferably 1,000 to 10,000. Specific examples of the silanol group-containing silicone resin thus obtained include methylpolysiloxane,
Examples thereof include phenyl polysiloxane and methylphenyl polysiloxane.

The coating resin composition of the present invention contains a polyvalent carboxylic acid (B) as an additive for stabilizing the silanol group-containing silicone resin. The polycarboxylic acid is not particularly limited as long as it can improve the storage stability of the coating material, but in the present invention,
It is preferable to use at least one selected from the group consisting of oxalic acid, citric acid, phthalic acid and terephthalic acid.

In the present invention, from the viewpoint of improving storage stability, the amount of polyvalent carboxylic acid added is 1 ppm to 10,000 pp relative to the silanol group-containing silicone resin.
m is necessary, but especially 10 ppm to 5,0
It is preferably 00 ppm. When it is 1 ppm or less, the storage stability cannot be improved, and when the addition amount is increased, the effect is saturated, and even when the addition amount exceeds 10,000 ppm, the effect does not increase any more, and on the contrary, it is undissolved. It is not preferable because polyvalent carboxylic acid precipitates or the coating film becomes cloudy. The polyvalent carboxylic acid may be added after the silanol group-containing silicone resin is produced, or may be added during the production. Unlike a monovalent carboxylic acid such as acetic acid, the polyvalent carboxylic acid has a low volatility, so that not only does the effect last, but also there is no odor.

It is preferable to add an inorganic filler (C) (simply referred to as an inorganic filler) to the coating resin composition of the present invention for coloring and thickening. The inorganic filler is
The inorganic filler is not particularly limited and can be appropriately selected and used from known inorganic fillers used in paints. Specific examples of the inorganic filler include silica, talc, glass frit, mica powder, barium sulfate, calcium carbonate, titanium oxide, inorganic pigments such as cadmium sulfate, metal powder such as aluminum powder, and aluminum paste. .

The resin composition for paint of the present invention is preferably diluted with an organic solvent from the viewpoint of facilitating handling when used as a paint. As the organic solvent, other than the solvent that can be used in the hydrolysis condensation reaction, ethyl acetate,
Examples thereof include esters such as butyl acetate. Two or more kinds of these solvents may be used in combination. When the polyvalent carboxylic acid is added after resin production, it is preferable to use an alcohol in which the polyvalent carboxylic acid is dissolved, from the viewpoint of uniformly mixing the silanol group-containing silicone resin and the polyvalent carboxylic acid. The coating resin composition of the present invention, if necessary,
In addition to the inorganic filler, various kinds of additives such as colorants such as various pigments and dyes, leveling agents, thickeners, and ultraviolet absorbers can be used.

The paint using the resin composition for paints of the present invention has good coating film properties and is used for various metal substrates, mortar boards, slate boards, concrete, wood, plastic substrates, glass and the like. However, in particular, the adhesion of the coating film is excellent for stainless steel plates and concrete. It is also useful as a paint vehicle for building exteriors and as a heat-resistant paint vehicle that can be applied to a metal substrate without a primer.

[0018]

EFFECTS OF THE INVENTION Since the resin composition for coating material of the present invention prevents the condensation reaction of silanol groups with each other by the polyvalent carboxylic acid, it can be preserved while maintaining good physical properties of the coating film as a conventional coating material. The stability is significantly improved.

[0019]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited thereto. Production Example of Silicone Resin Containing Silanol Group Production Example 1. In a 1.2 liter flask, 279 g (2 mol) of methyltrimethoxysilane, 198 g (1 mol) of phenyltrimethoxysilane, 530 g of xylene and 9.6 g of methanesulfonic acid (0.1 mol). 122 g (6.8 mol) of water was added dropwise over 30 minutes while stirring at 60 ° C. to cause a hydrolysis-condensation reaction, aged for 2 hours, and then cooled to 30 ° C. Then sodium hydrogen carbonate 10.
1 g (0.12 mol) and citric acid 2.1 g (0.01
Mol) was added and the mixture was stirred at 30 ° C. for 2 hours.

The obtained reaction solution was distilled at 80 ° C. under normal pressure to remove by-produced methanol, and the residue was washed with water. Next, it was dehydrated with anhydrous sodium sulfate, filtered, and further distilled under reduced pressure to obtain a xylene solution having a nonvolatile content (silanol group-containing silicone resin) content of 50% by weight. The viscosity of the obtained solution at 25 ° C. was 20 cs, and the silanol group content of the obtained resin was 3.6% by weight (C = 0.18) based on the silicone resin.

Production Example 2. In a one-liter flask, 136 g (1 mol) of methyltrimethoxysilane, 48 g (0.4 mol) of dimethyldimethoxysilane, 79 g (0.4 mol) of phenyltrimethoxysilane, 25 g of diphenyldichlorosilane. (0.1 mol) and 400 g of toluene were charged, and 90 g (5 mol) of water was added to 30 while stirring at 60 ° C.
The mixture was added dropwise over a period of 1 minute to cause a hydrolysis-condensation reaction, aged for 2 hours, and then cooled to 30 ° C. Then, 18.5 g (0.22 mol) of sodium hydrogen carbonate and 2.1 g of citric acid.
(0.01 mol) was added and the mixture was stirred at 30 ° C. for 2 hours.

The resulting reaction liquid was distilled at 80 ° C. under normal pressure to remove by-produced methanol, and the residue was washed with water. Next, it was dehydrated with anhydrous sodium sulfate, filtered, and further distilled under reduced pressure to obtain a toluene solution having a nonvolatile content (silanol group-containing silicone resin) content of 50% by weight. The viscosity of the obtained solution at 25 ° C. was 18 cs, and the silanol group content of the obtained resin was 3.9% by weight (C = 0.20) based on the silicone resin.

Example 1. In 200 g of xylene solution containing 50% by weight of the silicone resin obtained in Production Example 1,
Citric acid 1 mg (10 ppm relative to silicone resin)
Was added to a citric acid solution prepared by dissolving 2 g of 2-propanol, and the mixture was stirred and mixed to obtain a resin composition for coating material of the present invention. When the obtained coating resin composition was stored at 70 ° C. for 10 days, no change in viscosity was observed.

Embodiment 2 FIG. As a citric acid solution, 100 mg of citric acid (1,000 pp relative to silicone resin
m) was dissolved in 2 g of 2-propanol to prepare a coating resin composition in exactly the same manner as in Example 1 and stored in exactly the same manner as in Example 1. Was not seen at all.

Example 3. Citric acid 1 used in Example 1
A coating resin composition was prepared in exactly the same manner as in Example 1 except that 0 mg was replaced with phthalic acid 10 mg (100 ppm with respect to the silicone resin), and the coating resin composition was stored in exactly the same manner as in Example 1. No change was observed.

Example 4. In addition to the resin composition for coating material obtained in Example 2, barium sulfate powder 1 was further added as an inorganic filler.
When the coating resin composition containing 0 g was stored in the same manner as in Example 2, no change in viscosity was observed.

Example 5. In addition to the resin composition for coating material obtained in Example 2, aluminum paste 10 as an inorganic filler is further added.
When the resin composition for paint containing g was stored in the same manner as in Example 2, no change in viscosity was observed.

Example 6. A coating resin composition was prepared in exactly the same manner as in Example 4, except that the toluene solution of the silicone resin obtained in Production Example 2 was used in place of the xylene solution of the silicone resin obtained in Production Example 1. When stored in exactly the same manner as in Example 4, no change in viscosity was observed.

Example 7. A coating resin composition was prepared in the same manner as in Example 6 except that an aluminum paste was used instead of barium sulfate as the inorganic filler, and the resin composition was stored in the same manner as in Example 6. Was not seen at all.

Comparative Example 1. A coating resin composition was prepared in exactly the same manner as in Example 1 except that the citric acid solution was not used, and was stored in exactly the same manner as in Example 1, but after 5 days it gelled.

Comparative Example 2 A coating resin composition was prepared in the same manner as in Example 1 except that 10 g of barium sulfate powder was added without using a citric acid solution, and the resin composition was stored in the same manner as in Example 1. It gelled.

Comparative Example 3 A coating resin composition was prepared in the same manner as in Example 1 except that 10 g of an aluminum paste was added without using a citric acid solution, and the resin composition was stored in the same manner as in Example 1. Turned into

Comparative Example 4 A coating resin composition was prepared in exactly the same manner as in Example 6 except that the citric acid solution was not used, and was stored in exactly the same manner as in Example 1, but after 3 days it gelled.

Comparative Example 5 A coating resin composition was prepared in exactly the same manner as in Example 7 except that the citric acid solution was not used, and was stored in exactly the same manner as in Example 1, but after 7 days it gelled. The above results are summarized in Table 1.

[0035]

[Table 1]

Application example. The coating composition, which was stored at 70 ° C for 10 days, was applied to a polished ore plate and baked at 250 ° C for 30 minutes. The following coating film physical properties were measured according to JIS K5400, and cracks, peeling, etc. were measured. Those not recognized were marked with ◯, and those recognized were marked with x. Bending resistance: Mandrel diameter 4mm Impact resistance: DuPont mass 500g, shot type 1 / 2i
n, 30 cm Pencil hardness: Pencil scratching value Hand-drawing method Adhesion: Base tape method Solvent resistance: Xylene rubbing 100 times The above results are as shown in Table 2.

[0037]

[Table 2] The results in Table 2 demonstrate that in the case of the present invention in which a polycarboxylic acid is added, the physical properties of the coating film can be favorably maintained without gelation.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Isobe 1 Hitomi, Oita, Matsuida-cho, Usui-gun, Gunma 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (3)

[Claims] 1. A compound represented by the general formula R _a SiX _4-a (wherein R may be the same or different, a substituted or unsubstituted monovalent hydrocarbon group, and a is 0, 1 or 2). , X is an alkoxy group or a halogen atom) and is obtained by hydrolyzing and condensing a silane represented by the formula: or a partial hydrolysis-condensation product thereof.
General formula R _b Si (OH) _c (OR ′) _d O _{(4-bcd) / 2}
(In the formula, R may be the same or different, a substituted or unsubstituted monovalent hydrocarbon group, and R ′ has 1 to 1 carbon atoms.
0 is a substituted or unsubstituted monovalent hydrocarbon group, b, c
And d are 0.8 ≦ b ≦ 2, 0.04 ≦ c ≦ 1, 0 ≦ d
≦ 0.5 and a number satisfying 0.9 ≦ b + c + d ≦ 3), which is a resin composition for coating, which is obtained by adding a polycarboxylic acid (B) to a silanol group-containing silicone resin (A) represented by Therefore, the amount of (B) added is 1 pp relative to (A)
m-10,000 ppm, The resin composition for paints characterized by the above-mentioned. 2. The polycarboxylic acid is oxalic acid, citric acid,
The resin composition for paint according to claim 1, which is at least one selected from the group consisting of phthalic acid and terephthalic acid. 3. A coating resin composition obtained by further adding an inorganic filler (C) to the coating resin composition according to claim 1 or 2.