JPH0491176A - Heat-resistant paint - Google Patents

Abstract

PURPOSE:To obtain the subject paint giving a coating film having excellent heat-resistance and corrosion resistance and high hardness by dissolving or dispersing polymetallocarbosilane, a silicone resin, an inorganic filler and an alkali metal silicate in an organic solvent. CONSTITUTION:The objective paint can be produced by dispersing or dissolving 100 pts.wt. of a polymetallocarbosilane, preferably 50-500 pts.wt. of a silicone resin (e.g. dimethylpolysiloxane), preferably 50-500 pts.wt. of an inorganic filler (e.g. silicon carbide) and preferably 10-50 pts.wt. of an alkali metal silicate (e.g. sodium metasilicate nona-hydrate) in an organic solvent (e.g. toluene).

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a heat-resistant paint that can withstand use at high temperatures.

(Prior art and its problems) Japanese Patent Application Laid-Open No. 62-54768 discloses a heat-resistant paint in which polymetallocarbosilane, silicone resin, and inorganic filler are dispersed or dissolved in an organic solvent. The heat-resistant paint described in the above-mentioned publication can be baked in air, and the coating film obtained therefrom has the advantage of not only excellent heat resistance but also good corrosion resistance and impact resistance.

On the other hand, the coating film obtained by curing the polymetallocarbosilane by heating the paint described in the above-mentioned publication at a temperature of 250 to 450°C, which is the temperature for general baking, has a pencil hardness of 2H to 3.
H, has a relatively low hardness, and has a problem that needs to be solved in that the coating film is easily scratched.

(Technical means for explaining the problem) The present invention provides a heat-resistant paint that has excellent heat resistance and corrosion resistance and can provide a coating film with high hardness.

According to the present invention, a heat-resistant paint is provided in which a polymetallocarbosilane, a silicone resin, an inorganic filler, and an alkali metal silicate are dispersed or dissolved in an organic solvent.

The polymetallocarbosilane used in the present invention is an organosilicon polymer known per se, for example, Japanese Patent Publication No. 61-4
No. 9335, No. 62-60414, No. 63-
It can be prepared according to the methods described in JP-A No. 37139 and JP-A No. 63-49691. The descriptions in these publications are incorporated herein by reference.

A typical method for producing polymetallocarbosilane is a method in which a polycarbosilane having a number average molecular weight of 200 to 1,000 is reacted with a titanium or zirconium alkoxide. Through this reaction, polycarbosilane is a crosslinked polymer with a number average molecular weight of 700 to 100°000, in which some of the silicon atoms in its skeleton are bonded via oxygen atoms with titanium atoms or zirconium atoms. A metallocarbosilane is obtained.

An organic solvent solution of the above-mentioned polymetallocarbosilane is commercially available from Ube Industries Ltd. as Tyrannocoat face type.

Specific examples of the silicone resin in the present invention include dimethylpolysiloxane, methylphenylpolysiloxane,
Pure silicone resins such as diphenylpolysiloxane, pure silicone resins, alkyd resins, polyester resins,
Examples include modified silicones reacted with modifying resins such as acrylic resins and epoxy resins.

The blending ratio of the silicone resin is 10 to 900 parts by weight, particularly 50 to 900 parts by weight, per 100 parts by weight of polymetallocarbosilane.
Preferably, it is 500 parts by weight. If the blending ratio of silicone resin is too small, the flexibility of the coating film will be reduced due to baking, and if the ratio is too high, the heat resistance and corrosion resistance of the coating film will be reduced due to baking.

The inorganic filler in the present invention is at least one selected from oxides, borides, phosphates, silicates (excluding alkali metal silicates), silicides, borides, nitrides, and carbides. is used. For example,
Magnesium, calcium, barium, titanium, zirconium, chromium, manganese, iron, cobalt, nickel,
Examples include oxides, carbides, nitrides, silicides and borides of copper, zinc, boron, aluminum and silicon, borates, phosphates and silicates of magnesium, calcium or zinc.

The blending ratio of the inorganic filler is polymetallocarbosilane 10
0 parts by weight, 10 to 900 parts by weight, especially 50 to 50 parts by weight
Preferably, it is 0 parts by weight. By incorporating an inorganic filler, the adhesion of the coating film to the substrate during baking is improved, but if the proportion of the inorganic filler is too high, the flexibility of the coating film decreases.

As the alkali metal silicate in the present invention, the formula
MHO・n5iO2・xHzO [In the formula, i represents Li, Na, K or NR, (R is an alkyl group), n is 0.5 to 4, and x is O to 10
It is. ] Compounds represented by the following are generally used.

Specific examples thereof include sodium metasilicate nonahydrate, sodium orthosilicate hydrate, potassium metasilicate hydrate, and lithium metasilicate hydrate.

The blending ratio of alkali metal silicate is polymetallocarbosilane 100! 5 to 100 parts by weight, especially 1
If the blending ratio of the alkali metal silicate, which is preferably 0 to 50 parts by weight, is too small, the hardness of the painted film will not be sufficient, and even if the ratio is increased excessively, there is a limit to the increase in hardness. On the contrary, the flexibility of the coating film decreases.

As the @solvent in the present invention, any solvent can be used as long as it is capable of dissolving polymetallocarbosilane and silicone resin. Specific examples include toluene, xylene, n-butanol, isobutanol, butyl acetate, mineral spirit, solvent naphtha, ethyl cellosolve, and cellosolve acetate.

The proportion of the solvent used varies depending on the type and blending ratio of the film-forming components, but can be appropriately determined by those skilled in the art in accordance with the disclosure of the present invention.

The heat-resistant paint of the present invention is applied to a metal substrate or a non-metal substrate such as ceramic or firebrick by a known method such as brush coating, roll coating, spraying, or dipping, and then dried. Burned in.

The coating amount of the heat-resistant paint is preferably 20 to 100 g/rd; if the coating amount is too small, pinholes are likely to occur in the coating film, resulting in a decrease in corrosion resistance.

On the other hand, if the coating amount is excessively large, the coating film is likely to crack when exposed to high temperatures or cold/heat cycles.

The baking temperature is preferably 150°C or higher, particularly 200°C or higher. If the baking temperature is too low, the polymetallocarbosilane, which is one of the paint components, will not be sufficiently cured, resulting in a decrease in the strength of the coating film and also in its impact resistance. Incidentally, if the object to be coated is placed in a usage environment of 150° C. or higher after coating, the baking step may be omitted.

(Example) Examples and comparative examples are shown below. Unless otherwise specified in the examples, "%" and "parts" refer to "% by weight" and "parts by weight," respectively.

The pencil hardness of the coating film was measured according to JTS K 5400.

Furthermore, the heat resistance of the coating film was evaluated as follows.

After keeping the object to be coated in an air oven at 1000°C for 200 hours, it was taken out from the oven and slowly cooled in the air.
Next, a cross cut of 1 m + pitch was made in the coating film using a cutter knife, adhesive cellophane tape was pasted on this area, and the presence or absence of peeling of the coating film was examined after the adhesive cellophane tape was rapidly peeled off. The heat resistance was rated as "good" if no peeling of the coating film was observed, and the heat resistance was rated as "poor" if any peeling was observed.

Example 1 100 parts of a 50% xylene solution of polytitanocarbosilane (manufactured by Ube Industries, Ltd., Tyrannocoat Varnish Type), 100 parts of a 50% xylene solution of methylphenylpolysiloxane (manufactured by Toho Silicone Co., Ltd., TSR-116), carbonized A heat-resistant paint was prepared by mixing 100 parts of silicon powder, 30 parts of sodium metasilicate nonahydrate, and 70 parts of xylene using a mixer.

Separately, a stainless steel plate (sus 316L) with a thickness of 0.6 m+ was degreased with acetone and air-dried as a base material.

Approximately 30μ of the heat-resistant paint is applied to the base material using a spray gun.
- It was coated to a thickness, baked in an air oven at 300°C for 25 minutes, and then slowly cooled.

The pencil hardness of the formed coating film was 9H or higher.

Furthermore, the heat resistance of this coating film was "good."

Example 2 Example 1 was repeated except that 30 parts of sodium orthosilicate hydrate was used instead of sodium metasilicate nonahydrate.

The pencil hardness of the resulting coating film is 9H or higher, and the heat resistance is "
It was "Good".

Comparative Example 1 Example 1 was repeated except that sodium metasilicate nonahydrate was not blended.

The pencil hardness of the resulting coating film was 2H, and the heat resistance was "good".
Met.

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 resulting coating film is 9H or higher, and the heat resistance is "
It was "Good".

Example 4 Example 1 was repeated except that 50 parts of zirconium oxide powder was used instead of silicon carbide powder.

The pencil hardness of the resulting coating film is 9H or higher, and the heat resistance is "
It was "Good".

Claims (1)

[Claims] A heat-resistant paint characterized in that a polymetallocarbosilane, a silicone resin, an inorganic filler, and an alkali metal silicate are dispersed or dissolved in an organic solvent.