JPH04239077A - 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 coating film that is resistant to oil stains.

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 this 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, oil stains adhering to the surface of the coating film formed from the coating material described in the above-mentioned publication cannot be easily removed. Although this oil stain can be removed using an alkaline liquid, the coating film does not have sufficient resistance to alkaline liquids, and therefore cannot be repeatedly washed with alkaline liquids. As described above, the above-mentioned paint has a problem in that it is difficult to remove oil stains that adhere to the paint film obtained by baking the paint on steak plates, for example, in applications where oil stains frequently adhere.

0004

[Technical means for explaining the problem] The present invention provides a coated plate having excellent heat resistance and having a coating film formed on its surface to which oil stains are difficult to adhere. The present invention is a heat-resistant paint in which polyborosiloxane, silicone resin, inorganic filler, and powdered fluororesin are 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.

Specific examples of the fluororesin in the present invention include polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, and ethylene/fluoroethylene alternating polymers. Union,
Examples include tetrafluoroethylene/fluoroalkyl vinyl ether copolymer and tetrafluoroethylene/perfluorosulfonyl fluoride vinyl ether copolymer. These fluororesins are described, for example, in Plastic Materials Course 6 "Fluororesins" published by Nikkan Kogyo Shimbun.

Among the above-mentioned fluororesins, tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer has good heat resistance and mold release properties, and has a low melt viscosity and can be uniformly dispersed in the coating film formed from the paint. It is preferably used in the present invention. The average particle size of powdered fluororesin is generally 5~
It is 50 μm. The fluororesin imparts oil repellency to the coating film formed from the heat-resistant paint of the present invention, which makes it difficult for oil stains to adhere to the coating film, and allows the attached oil stains to be easily wiped off.

The blending ratio of the fluororesin is 10 to 200 parts by weight, especially 2 parts by weight, per 100 parts by weight of polyborosiloxane.
It is preferably 0 to 100 parts by weight. If the blending ratio of the fluororesin is too small, it will not be possible to impart sufficient oil repellency to the coating film, and even if the blending ratio is excessively large, the oil repellency of the coating film will not further improve, making it difficult for industrial use. has no meaning.

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. dried and baked.

[0015] 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.

[0016] 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.

[0017]

[Example] Examples and comparative examples are shown below. Unless otherwise specified below, "%" and "parts" refer to "% by weight" and "parts by weight," respectively.

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, it was taken out from the oven and slowly cooled in the air.
Next, cross cuts with a pitch of 1 mm were made in the coating film using a cutter knife, and 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.

Ease of wiping off oil stains attached to the paint film (
Corrosion oil stain resistance) was evaluated as follows. Approximately 10 μm droplets of salad oil were placed on the object to be coated in several places, kept in an air oven at 300°C for 1 hour, then removed from the oven and slowly cooled in the air, and then removed with wet gauze. The appearance of the coating film was inspected. A coating film with no foreign matter attached to it and no traces of oil adhesion is considered to be "good" in terms of corrosion resistance, and a coating film with foreign matter attached or traces of oil attached to it is considered to be resistant to corrosion. Contaminated with cooking oil as "defective".

Example 1 100 parts of a 50% xylene solution of polybolysiloxane with a number average molecular weight of 1500 prepared according to the method described in Japanese Patent Publication No. 58-4732, 100 parts of a 50% xylene solution of methylphenylpolysiloxane (manufactured by Toshiba Silicone Corporation) , TSR-116), 100 parts of silicon carbide powder, 50 parts of tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (manufactured by DuPont Mitsui Fluorochemicals, MP-10), and 50 parts of xylene were mixed in a mixer to make a heat-resistant mixture. A color paint was prepared. Apart from this, a stainless steel plate with a thickness of 0.6 mm (
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 heat resistance and corrosion oil stain resistance of the formed coating film were both "good".

Comparative Example 1 Example 1 was repeated except that a tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer was desired. The heat resistance of the formed coating film was "good", but the resistance to corrosion oil staining was "poor".

Example 2 Example 1 was repeated except that 50 parts of polytetrafluoroethylene (Luburon L-2, manufactured by Daikin Industries, Ltd.) was used instead of the tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer. The heat resistance and corrosion oil stain resistance of the formed coating film were both "good".

Claims (1)

[Claims] 1. A heat-resistant paint comprising polyborosiloxane, silicone resin, inorganic filler, and powdered fluororesin dissolved or dispersed in an organic solvent.