JPH06220393A - Heat-resistant coating material - Google Patents

Abstract

PURPOSE:To obtain a heat-resistant coating material having high hardness, excellent heat resistance, hardly sealing oil stain by dissolving of dispersing a polymetallocarbosilane, a silicone resin, an inorganic filler, a specific resin an a specific compound into an organic solvent. CONSTITUTION:(A) A polymetallocarbosilane, (B) a silicone resin, (C) an inorganic filler (e.g. silicon oxide), (D) a powdery fluororesin (preferably tetrafluoroethylene/perfluoroalkylene vinyl ether copolymer) and (E) an alkali metal silicate (e.g. sodium metasilicate 9 hydrate) are dissolved or dispersed into an organic solvent to give the objective coating material. The component A, for example, is obtained by reacting a polycarbosilane having 200-1,000 number-average molecular weight with titanium or zirconium. Preferably 100 pts.wt. of the component A are mixed with 50-500 pts.wt. of the component B, 50-500 pts.wt. of the component C, 20-100 pts.wt. of the component D and 10-50 pts.wt. of the component E.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant paint which is resistant to use at high temperatures and is resistant to oil stains.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 62-54768 discloses a heat resistant coating in which a polymetallocarbosilane, a silicone resin and an inorganic filler are dispersed or dissolved in an organic solvent. The heat-resistant paint described in the above publication is capable of baking in air, and the coating film obtained from this exhibits excellent heat resistance and good corrosion resistance and impact resistance.
Have advantages.

[0003]

On the other hand, the paint described in the above publication has a general baking temperature of 250.
The coating film obtained by heating to ~ 450 ° C to cure the polymetallocarbosilane has a pencil hardness of 2H to 3H and relatively low hardness, and the coating film is apt to be scratched. Have Further, oil stains adhering to the surface of the coating film formed from the paint described in the above publication cannot be easily removed. Although this oil stain can be removed by using an alkaline liquid, the coating film has a problem to be solved that it does not have sufficient resistance to the alkaline liquid.

An object of the present invention is to provide a heat-resistant coating material having excellent heat resistance, high hardness, and hard to adhere oil stains.

[0005]

To achieve the above object, according to the present invention, polymetallocarbosilane, a silicone resin, an inorganic filler, a powdery fluororesin, and an alkali metal silicate are organic solvents. A heat-resistant paint dispersed or dissolved in is provided. The polymetallocarbosilane in the present invention is an organic silicon polymer known per se, and is disclosed in, for example, JP-B-61-49335 and JP-A-62-149335.
No. 60414, No. 63-37139, No. 63.
It can be prepared according to the method described in JP-A-49691. The descriptions of these publications are referred to as part of the present specification. A typical production method of polymetallocarbosilane is
It is a method of reacting a polycarbosilane having a number average molecular weight of 200 to 1000 with a titanium or zirconium alkoxide. By this reaction, polycarbosilane is a cross-linked polymer having a number average molecular weight of 700 to 100,000, in which a part of silicon atoms in the skeleton are bonded with titanium atoms or zirconium atoms through oxygen atoms. A metallocarbosilane is obtained. An organic solvent solution of the above polymetallocarbosilane is commercially available from Ube Industries, Ltd. as Tyrannocoat® varnish type.

Specific examples of the silicone resin in the present invention include pure silicone resins such as dimethylpolysiloxane, methylphenylpolysiloxane and diphenylpolysiloxane, and conversion of pure silicone resin into alkyd resin, polyester resin, acrylic resin, epoxy resin and the like. The modified silicone reacted with the resin for use is exemplified. The mixing ratio of the silicone resin is polymetallocarbosilane 100.
10 to 900 parts by weight, especially 50 to 500 parts by weight
It is preferably part by weight. If the blending ratio of the silicone resin is too small, the flexibility of the baked coating film is lowered, and if the proportion is too high, the heat resistance and corrosion resistance of the baked coating film are lowered.

Specific examples of the fluororesin in the present invention include polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, ethylene / fluoroethylene alternating polymer. Coalescing,
Examples thereof include a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer and a tetrafluoroethylene / barfluorosulfonyl fluoride vinyl ether copolymer. These fluororesins are described in, for example, Plastic Material Lecture 6 “Fluororesin” published by Nikkan Kogyo Shimbun. Among the above fluororesins, the tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer is excellent in heat resistance and releasability and has a low melt viscosity and is uniformly dispersed in a coating film formed from a coating material. It has excellent characteristics and is preferably used. The average particle size of the powdery fluororesin is generally 5 to 50 μm. The fluororesin imparts oil repellency to the coating film formed from the heat-resistant coating material of the present invention, and therefore oil stains are unlikely to adhere to the coating film and the adhered oil stains can be easily wiped off.

The mixing ratio of the fluororesin is preferably 10 to 200 parts by weight, more preferably 20 to 100 parts by weight, based on 100 parts by weight of polymetallocarbosilane. If the blending ratio of the fluororesin is too small, it is impossible to impart sufficient oil repellency to the coating film, and even if the blending ratio is excessively increased, the oil repellency of the coating film is not further improved industrially. has no meaning.

As the inorganic filler in the present invention, at least one selected from oxides, borides, phosphates, silicates, silicides, nitrides and carbides is used.
Examples include magnesium, calcium, barium, titanium, zirconium, chromium, manganese, iron, cobalt, nickel, copper, zinc, boron, aluminum,
Silicon oxides, carbides, nitrides, silicides, borides, lithium, sodium, potassium, magnesium,
Examples include calcium or zinc borate, phosphate, and silicate. The mixing ratio of the inorganic filler is preferably 10 to 900 parts by weight, and particularly preferably 50 to 500 parts by weight, per 100 parts by weight of polymetallocarbosilane. If the blending ratio of the inorganic filler is too small, the adhesiveness of the coating film is lowered, and if the mixing ratio is too high, the flexibility of the coating film is lowered.

The alkali metal silicate in the present invention has the formula M ₂ O.nSiO ₂ .xH ₂ O [wherein M represents Li, Na, K or NR ₄ (R is an alkyl group), and n is It is 0.5 to 4. x is 0-10. ] The compound represented by the following is generally used. Specific examples thereof include sodium metasilicate nonahydrate, sodium orthosilicate hydrate, potassium metasilicate hydrate, and lithium metasilicate hydrate. The mixing ratio of the alkali silicate is preferably 5 to 100 parts by weight, particularly 10 to 50 parts by weight, based on 100 parts by weight of polymetallocarbosilane. If the blending ratio of the alkali metal silicate is too small, the hardness of the coating film is not sufficient, and even if the blending ratio is excessively increased, there is a limit to the increase in altitude, and conversely the flexibility of the coating film is small. Become.

As the organic solvent in the present invention, any solvent capable of dissolving polymetallocarbosilane and silicone resin can be used. Specific examples thereof include toluene, xylene, n-butanol, isobutanol, butyl acetate, mineral spirits, solvent naphtha, ethyl cellosolve, and cellosolve acetate. The proportion of the organic solvent used varies depending on the type and blending proportion of the film-forming component, but can be appropriately determined by those skilled in the art according to the disclosure of the present invention.

The heat-resistant paint of the present invention is applied to a metal base material or a non-metal base material such as ceramics or refractory bricks by a means known per se such as brush coating, roll coater, spraying or dipping, and then dried. And then baked. The coating amount of the heat resistant coating composition of the present invention is preferably ²⁰ to 100 g / m ² . If the coating amount is excessively small, pinholes are likely to occur in the coating film, resulting in poor corrosion resistance. On the other hand,
If the coating amount is excessively large, cracks are likely to occur in the coating film when the coating film is exposed to a high temperature or a thermal cycle.

The baking temperature is 150 ° C. or higher, especially 200
It is preferably at least ° C. If the baking temperature is excessively low, the polymetallocarbosilane, which is one of the paint components, will not be sufficiently cured, and the strength of the coating film will be low and the impact resistance will be low. It should be noted that after coating the paint, the object to be coated is 150 ° C.
The baking step can be omitted when the above-mentioned use environment is set.

[0014]

EFFECTS OF THE INVENTION The heat resistant coating of the present invention is applied to a desired solid surface and baked at a temperature of 150 ° C. or higher to withstand use at high temperatures, have high hardness, and fix oil stains. Since it gives a difficult coating, it is suitable for coating cooking utensils, industrial parts, chemical equipment, etc., which are prone to oil stains.

[0015]

EXAMPLES Examples and comparative examples will be shown below. Unless otherwise specified in the examples, “%” and “part” refer to “% by weight” and “part by weight”, respectively. The pencil hardness of the formed coating film was measured according to JIS K5400. The heat resistance of the coating film was evaluated as follows. After holding the object to be coated in an air oven at 1000 ° C for 200 hours, take it out of the oven and slowly cool it in the air. Then, put a 1mm pitch cross-cut on the coating film with a cutter knife and put an adhesive cellophane tape on this part. It was examined whether or not the coating film was peeled off after the film was attached and rapidly peeled off. The heat resistance was “good” when the peeling of the coating film was not observed, and the heat resistance was “poor” when the peeling was partially observed.

The corrosion resistance of the coating film was evaluated as follows.
The article to be coated was kept in an air oven at 400 ° C. for 200 hours, and then sprayed with 4% saline for 200 hours, and the appearance of the coating film was observed with a 50 × microscope. When corrosion was not observed, the corrosion resistance was “good”, and when rust was observed, the corrosion resistance was “poor”.

The easiness of wiping off oil stains with the coating film (corrosion resistance to corrosion oil) was evaluated as follows. A few drops of salad oil of about 10 μm are dropped on the object to be coated, and 30
After holding in an air oven at 0 ° C. for 1 hour, it was taken out of the oven, gradually cooled in air, and then the appearance of the coating film was examined after removing stains with wet gauze. Corrosion-resistant oil stain resistance is “good” when no foreign matter is attached to the coating film and no trace of oil is observed. It was defined as "poor" due to edible oil contamination.

Example 1 50% xylene solution of polytitanocarbosilane (manufactured by Ube Industries, Ltd., Tyrannocoat® varnish type) 100
Parts, 100 parts of 50% xylene solution of methylphenyl polysiloxane (TSR-116 manufactured by Toshiba Silicone Co., Ltd.),
100 parts of silicon carbide powder, 30 sodium metasilicate hydrate
Parts and 70 parts of xylene were mixed with a mixer to prepare a heat resistant paint. Separately from this, a stainless steel plate (SUS 316L) having a thickness of 0.6 mm was degreased with acetone and then air-dried. The heat resistant paint is applied to the base material with a spray gun to a thickness of about 30 μm, and the applied heat is applied in an air oven for 300 times.
After firing and baking at 25 ° C. for 25 minutes, it was gradually cooled. The pencil hardness of the obtained coating film was 9H or more, and the heat resistance and the corrosion oil stain resistance were "good".

Comparative Example 1 Example 1 was repeated except that the sodium metasilicate nonahydrate and the tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer were not compounded. The heat resistance of the obtained coating film was “good”, but the pencil hardness was 2H,
Corrosion resistance to corrosion oil was also "poor".

Example 2 Example 1 was repeated except that 30 parts of sodium orthosilicate were used instead of sodium metasilicate nonahydrate. The pencil hardness of the obtained coating film was 9H or more, and the heat resistance and the corrosion oil stain resistance were "good".

Example 3 Example 1 was repeated except that 200 parts of silicon nitride powder was used instead of silicon carbide powder. The pencil hardness of the obtained coating film was 9H or more, and the heat resistance and the corrosion oil stain resistance were "good".

Claims (1)

[Claims] 1. A heat-resistant coating material in which polymetallocarbosilane, silicone resin, inorganic filler, powdered fluororesin, and alkali metal silicate are dispersed or dissolved in an organic solvent.