JPH04239078A - heat resistant paint - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 that is heat-resistant and capable of forming a highly hard coating film.

0002

[Prior art and its problems] Japanese Patent Application Laid-Open No. 57-20046
Publication No. 2 discloses a heat-resistant paint in which polyborosiloxane, a silicone resin, and an 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 polyborosiloxane by heating the paint described in the above publication to a general baking temperature of 250 to 450°C has a pencil hardness of 2H to 3H. It has a relatively low hardness and the paint film is easily scratched, which is a problem that needs to be solved. Therefore,
The paint film obtained by baking this paint on steak plates for applications requiring surface hardness, for example, is easily scratched by knives and forks, and the paint film is likely to peel off in a relatively short period of time.

0004

[Technical means for explaining the problem] The present invention provides a heat-resistant paint that can form a highly hard coating film while maintaining the excellent heat resistance of a polyborosiloxane paint. The present invention provides polyborosiloxane, silicone resin,
Inorganic filler, alkyl alkoxysilane, and titanium,
This is a heat-resistant paint in which a metal alkoxide selected from zirconium and aluminum is dissolved or dispersed in an organic solvent.

The polyborosiloxane used in the present invention is a known organosilicon polymer, for example, as disclosed in Japanese Patent Publication No. 58-473.
It can be prepared according to the method described in Publication No. 2. The number average molecular weight of polyborosiloxane is usually 500 to 10
000, preferably 1000-5000.

Specific examples of silicone resins used in the present invention include pure silicone resins such as dimethylpolysiloxane, methylphenylpolysiloxane, and diphenylpolysiloxane, and modified pure silicone resins such as alkyd resins, polyester resins, acrylic resins, and epoxy resins. For example, modified silicone reacted with a commercially available resin.

The blending ratio of the silicone resin is preferably 10 to 900 parts by weight, particularly 50 to 500 parts by weight, per 100 parts by weight of the polyborosiloxane. If the blending ratio of silicone resin is too small, the flexibility of the baked coating will decrease, and if the proportion is too high, the heat resistance and corrosion resistance of the baked coating will decrease.

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 oxides, carbides, nitrides, silicides of magnesium, calcium, barium, titanium, zirconium, chromium, manganese, iron, cobalt, nickel, copper, zinc, boron, aluminum, and silicon.
borides, lithium, sodium, potassium, magnesium, calcium or zinc borates, phosphates;
Examples include silicates.

The blending ratio of the inorganic filler is 10 to 900 parts by weight, particularly 5 parts by weight, per 100 parts by weight of polyborosiloxane.
It is preferably 0 to 500 parts by weight. By blending an inorganic filler, the adhesion of the baked coating film to the base material is improved, but if the blending ratio becomes too high, the flexibility of the coating film decreases.

The alkylalkoxysilane in the present invention has the formula R1nSi(0R2)4-n (wherein R1 and R2 each represent an alkyl group, n represents 1 to 3). Compounds represented by are generally used. Specific examples include methyltrimethoxysilane, ethyltrimethoxysilane, butyltriethoxysilane, methyltripropoxysilane, dimethyldiethoxysilane, diethyldibutoxysilane,
Examples include triethyl ethoxysilane and trimethylbutoxysilane.

[0011] The blending ratio of alkyl alkoxysilane is:
It is preferably 0.2 to 10 mol, particularly 0.5 to 5 mol, per 100 g of polyborosiloxane. If the blending ratio of alkyl alkoxysilane is too small, the hardness of the painted film will not be sufficient, and if the blending ratio is too large, the initial adhesion of the painted film to the substrate will decrease.

The metal alkoxide selected from titanium, zirconium and aluminum in the present invention has the formula R3mM(OR4)4-m (wherein R3 and R4 each represent an alkyl group, and M represents titanium or zirconium). and m is 1 to 3), or a compound represented by the formula R5pAl(OR6)
A compound represented by 3-p (wherein R5 and R6 each represent an alkyl group, and p is 1 to 2) is used. Specific examples include tetraethoxytitanium,
Tetrabutoxytitanium, tetramethoxyzirconium,
Examples include tetrapropoxyzirconium, tetrabutoxyzirconium, methyltributoxytitanium, dimethyldiethoxytitanium, ethyltributoxyzirconium, dimethyldibutoxyzirconium, trimethyltriethoxytitanium, triethoxyaluminum, tributoxyaluminum, and tripropoxyaluminum.

The mixing ratio of the metal alkoxide mentioned above is preferably 0.1 to 5 mol, particularly 0.25 to 2 mol, per 100 g of polyborosiloxane. If the blending ratio of metal alkoxide is too small, the hardness of the painted film will not be sufficient, and if the blending ratio is too high, the stability as a paint will be impaired and it will gel during short-term storage.

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 is applied to metal substrates, electric wires, or non-metallic substrates such as ceramics and refractory bricks by means known per se such as brush coating, roll coater, spraying, and dipping, and then dried and baked.

[0016] The amount of heat-resistant paint applied is 20 to 100 g/m.
It is preferable that it is 2. 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 excessively large, cracks are likely to occur in the coating film when the coating film is exposed to high temperatures or to cooling/heating cycles.

[0017] The baking temperature is 150°C or higher, especially 200°C.
It is preferable that it is above. If the baking temperature is too low, polymetallocarbosilane, which is one of the paint components, will not be sufficiently cured, resulting in lower strength and impact resistance of the paint film. In addition, the temperature of the object to be coated after painting is 150℃.
When placed in the above usage environment, the baking step can be omitted.

[0018]

[Example] Examples and comparative examples are shown below. Unless otherwise specified below, "%" and "parts" refer to "% by weight" and "parts by weight," respectively. The pencil hardness of the formed coating film was measured according to JISK5400.

The heat resistance of the coating film was evaluated as follows. That is, the object to be painted is kept in an air oven at 1000°C for 200 hours, then taken out of the oven and slowly cooled in the air, then crosscuts with a pitch of 1 mm are made in the coating film using a cutter knife, and adhesive cellophane tape is applied to this area. was applied, and the presence or absence of peeling of the coating film was examined after it was rapidly peeled off. If no peeling of the paint film is observed, the heat resistance is ``good'', and if some peeling is observed, the heat resistance is ``good''.
``Defect.''

Example 1 Polybolysiloxane with a number average molecular weight of 1500 prepared according to the method described in Japanese Patent Publication No. 58-4732.
% xylene solution, 50% xylene solution of methylphenylpolysiloxane (manufactured by Toshiba Silicone Co., Ltd., TSR
-116) 100 parts, silicon carbide powder 100 parts, methyltrimethoxysilane 150 parts, tetrabutoxytitanium 2
A heat-resistant paint was prepared by mixing 50 parts of xylene and 70 parts of xylene using a mixer. Apart from this, the base material has a thickness of 0.
A 6 mm stainless steel plate (SUS 316L) was degreased with acetone and then air-dried.

[0021] The heat-resistant paint was applied to the base material to a thickness of about 30 μm using a spray gun, and then heated in an air oven for 300 μm.
After baking at ℃ for 25 minutes, it was slowly cooled. The pencil hardness of the formed coating film was 8H or higher. Moreover, the heat resistance of this coating film was "good".

Example 2 Example 1 was repeated except that 400 parts of tetrabutoxyzirconium was used instead of tetrabutoxytitanium. The pencil hardness of the resulting coating film was 8H or higher, and the heat resistance was "good".

Comparative Example 1 Example 1 except that tetrabutoxytitanium was not blended.
repeated. The pencil hardness of the resulting coating film was 2H,
Heat resistance was "good".

Example 3 Example 1 was repeated except that 200 parts of silicon nitride powder was used in place of silicon carbide powder. The pencil hardness of the resulting coating film was 8H or higher, and the heat resistance was "good".

Example 4 Example 1 was repeated except that 50 parts of zirconium oxide powder was used in place of the silicon carbide powder. The pencil hardness of the resulting coating film was 8H or higher, and the heat resistance was "good".

Claims (1)

[Claims] 1. A heat-resistant paint comprising a polyborosiloxane, a silicone resin, an inorganic filler, an alkyl alkoxysilane, and an alkoxide of a metal selected from titanium, zirconium, and aluminum dissolved or dispersed in an organic solvent.