JPH0491180A - Heat-resistant paint - Google Patents

Abstract

PURPOSE:To obtain the subject paint giving a coating film having excellent heat-resistance and free from generation of pinholes even at high temperature by dispersing or dissolving a polymetallocarbosilane, a silicone resin, an inorganic filler and a glass frit having a specific softening point 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 20-100 pts.wt. of glass frit having a softening point of 400-600 deg.C in an organic solvent.

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 formed from the paint described in the above publication was
When exposed to temperatures above 00°C, the polymetallocarbosilane undergoes volumetric shrinkage as it converts to an inorganic substance, and pinholes that reach the substrate may form. The pinholes that occur in this paint film limit its use in applications where it is exposed to corrosive gases, which is a problem that needs to be solved.

(Technical means for explaining the problem) The present invention is a heat-resistant paint that has excellent heat resistance and can provide a coating film in which pinholes are not generated or are significantly suppressed even at high temperatures. I will provide a.

According to the present invention, a heat-resistant paint is provided in which a polymetallocarbosilane, a silicone resin, an inorganic filler, and a glass frit having a softening point of 400 to 600°C 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. 61-1
No. 49335, No. 62-60414, No. 63
It can be prepared according to the methods described in JP-A-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 has a number average molecular weight of 700 to 100, in which some of the silicon atoms in its skeleton are bonded with titanium atoms or zirconium atoms via oxygen atoms.

A polymetallocarbosilane which is a crosslinked polymer of 0.000 is obtained.

An organic solvent solution of the above-mentioned polymetallocarbosilane is commercially available from Ube Industries (2) as Tyrannocoat (varnish 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.

As the inorganic filler in the present invention, at least one selected from oxides, borides, phosphates, silicates, silicides, borides, nitrides, and carbides is used. Examples include mag namesium, calcium, barium,
Titanium, zirconium, chromium, manganese, iron, cobalt, nickel, copper, zinc, boron, aluminum, silicon oxides, carbides, nitrides, silicides, borides, lithium, sodium, potassium, magnesium, calcium or zinc. Examples include borates, phosphates, and silicates.

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.

Examples of the glass used as the material for the glass lift with a softening point of 400 to 600"C in the present invention include phosphate glass, borosilicate glass, and lead glass. Among these, lead glass is toxic, so Heat-resistant paints containing these should be avoided for civilian applications, such as cooking utensils.On the other hand, phosphate glasses and borosilicate glasses are non-toxic and should therefore be used in all types of applications, including civilian ones. can be used.

Glass lift can be prepared according to a method known per se, in which molten glass is sprayed into water and quenched.

There are no particular restrictions on the particle size of glass lift, but
Generally, it is a 2-20μ button.

The blending ratio of glass frit is 10 to 200 parts by weight, particularly 20 to 200 parts by weight, per 100 parts by weight of polymetallocarbosilane.
Preferably it is 100 parts by weight. If the blending ratio of glass frit is too small, the chemical resistance at high temperatures, that is, the durability against corrosive gases will not be sufficient, and if the ratio is increased too much, the flexibility of the coating will decrease.

When the softening point of the glass frit is lower than 400° C., the glass frit sometimes melts and aggregates during paint baking, resulting in a decrease in the adhesion of the paint film and a decrease in mechanical strength. If the softening point is higher than 600''C, the effect of preventing pinholes in the coating film will be reduced.

As the organic 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 organic solvent to be used varies depending on the type and blending proportion of the film-forming components, and 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 can be applied to metal substrates or non-metallic substrates such as ceramics and refractory bricks with a brush. , by means known per se such as roll coater, spraying, dipping, etc., followed by drying and baking.

The amount of heat-resistant paint applied is preferably 20 to 100 g/m. If the coating amount is too small, pinholes are likely to occur in the coating film, resulting in decreased corrosion resistance.

On the other hand, if the coating amount is too 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, especially 200"C or higher. If the baking temperature is too low, the polymetallocarbosilane, which is one of the paint components, will not harden sufficiently and the strength of the paint film will deteriorate. As the impact resistance decreases, so does the impact resistance.In addition, if the object to be coated is placed in a usage environment of 150° C. or higher after being coated with the paint, 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 heat resistance of the coating film was evaluated as follows. The object to be painted was kept in an air oven at 1000°C for 200 hours, then taken out of the oven and slowly cooled in the air. Then, a 1-pitch cross cut was made in the coating film with a cutter knife, and adhesive cellophane tape was applied to this area. The presence or absence of peeling of the coating film after pasting and rapid peeling was examined. 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.

The presence or absence of pinhole-like peeling portions in the coating film was evaluated as follows. The object to be coated is kept in an air oven at 1000°C for 200 hours, then taken out of the oven and slowly cooled, and then sprayed with salt water for 200 hours. Observed with a microscope. Rust formation and blistering of the paint film were observed on those with pinhole-like peeling.

Example 1 50% xylene solution of polytitano levosilane (manufactured by Ube Industries, Tyrannocoat [F] varnish type) 100
parts, 100 parts of a 50% xylene solution of methylphenylpolysiloxane (manufactured by Toho Silicone Co., Ltd., TSR-116),
A heat-resistant paint was prepared by mixing 100 parts of silicon carbide powder, 50 parts of phosphate glass frit (manufactured by Nippon Ferro Co., Ltd., 0l-41026), and 50 parts of xylene using a mixer.

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

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

The heat resistance of the resulting coating film was "good" and no pinhole-like peeling was observed.

Example 2 Example 1 was repeated except that 50 parts of borosilicate glass frit (manufactured by Nippon Ferro, 12-3615) was used in place of the borate glass frit.

Claims (1)

[Claims] A heat-resistant paint comprising polymetallocarbosilane, silicone resin, inorganic filler, and glass frit having a softening point of 400 to 600°C dispersed or dissolved in an organic solvent.