JP2521466B2 - Heat-resistant coating material for molten aluminum plated steel sheet - Google Patents

Description

Description: BACKGROUND AND PROBLEM OF THE INVENTION The present invention relates to a heat resistant coating material for hot dip aluminum plated steel sheet.

In general, heat-resistant coating materials or heat-resistant paints used for metal substrates are heat-resistant organic or inorganic binders, for example, using a silicone resin, and most of them have a formulation in which an extender pigment and an anticorrosive pigment are mixed. Further, it has been proposed to add a frit in order to enhance the adhesiveness with the metal base at a higher temperature. However, this is for the purpose of improving the heat-resistant adhesiveness in a high temperature range by using it on a normal steel sheet.

Conventionally, ordinary steel has been the most commonly used metal material for heat-resistant parts, but various treated steel sheets have come to be widely used due to their corrosion resistance and adhesion to coating materials such as paints. It was Among them, the hot-dip aluminized steel sheet has a relatively high heat resistance, and since it has excellent workability and corrosion resistance, it is widely used as a heat resistant component. However, the heat-resistant limit temperature of aluminized steel sheet is 500 to 550 ° C, and long-term durability is inferior at temperatures above 500 ° C. That is, when the aluminum-plated steel sheet is heated at a temperature of 500 ° C, the surface aluminum layer is temporarily melted, the surface layer moves, and Fe-Al alloying proceeds. If the surface coating is applied at this point, the conventional heat-resistant coating material cannot follow the surface change of the aluminum-plated steel sheet and peels off, so that it cannot be used at high temperature. In general, heat-resistant parts are mostly used in a wide temperature range from low temperature to high temperature, so as mentioned above, they do not peel at high temperatures and can be used in a wide temperature range. There is a demand for coating materials.

Solution The present inventor therefore studied heat-resistant coating materials having excellent adhesiveness even at a heat-resistant limit temperature of an aluminum-plated steel sheet, an organic or inorganic binder, aluminum powder 10 to 100 parts by weight of frit powder We have succeeded in solving the above problems by using a coating material prepared by mixing powders mixed at a ratio of 90 parts by weight.

Preferred Implementation Method The organic and inorganic binders that can be used in the coating material of the present invention may be silicone resins, which are generally used as binders for heat-resistant paints, and silicon-based inorganic binders.

The frit may be any of lead-free phosphoric acid type, lead-containing type, lead-free soda type, etc., but one having a melting point lower than the temperature at which the surface of the aluminized steel sheet changes state by heating is selected. In general, one having a melting point in the range of 350 to 500 ° C. is desirable.

The aluminum powder is preferably a highly pure metal aluminum powder, and may be surface-treated for the purpose of enhancing the dispersion effect.

The mixing ratio of frit powder and aluminum powder is 10
The latter is 10 to 90 parts by weight with respect to 0 parts by weight, and if the proportion of aluminum powder is too low or too high, the adhesiveness in the high temperature range decreases. Especially frit powder 100
A range of 40 to 60 parts by weight is preferable with respect to parts by weight.

The coating material of the present invention may contain a color pigment and an extender pigment. These pigments must have heat resistance, and coloring pigments include metal oxides such as iron oxide, titanium oxide, chromium oxide, and cobalt oxide, and mixtures thereof, and extender pigments such as talc and mica. There are silicate compounds, calcium carbonate, barium sulfate and the like.

The amount of the binder must be in a low temperature range, that is, in a proportion such that the frit powder has sufficient adhesiveness to the metal material before melting to form a new binder.

Once the coated covering material is heated to 500 ° C or higher, the frit melts and a new film that becomes a binder is formed, so thermal oxidation and melting of the aluminum plating surface,
It suppresses changes such as growth of the alloy layer, absorbs the difference in thermal expansion between the metal material and the coating material, and peels off with normal heat-resistant paint.
It has excellent adhesiveness even at temperatures above 0 ° C.

Example Each component was blended as in Formulation Examples 1 to 5, and this was coated on a solvent-degreased hot-dip aluminized steel sheet by air spraying so that the film thickness when dried was 10 to 30 μ, and at 180 ° C. 20
Baked for minutes. A heat resistance and durability test was conducted on this test piece, and the results shown in the table were obtained.

Claims (2)

(57) [Claims] 1. A heat-resistant coating material for a hot-dip aluminized steel sheet, which comprises a mixture of an organic or inorganic binder with 100 parts by weight of frit powder and 10-90 parts by weight of aluminum powder. 2. The heat-resistant coating material for hot-dip aluminized steel sheet according to claim 1, wherein the mixing ratio of the aluminum powder is 40 to 60 parts by weight with respect to 100 parts by weight of the frit powder.