JPH0210105B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to enameled stainless steel products such as building materials, kitchen utensils, bathtubs, and pipes for chemical plants, etc., and does not require any special pretreatment and can be applied to stainless steel surfaces. This invention relates to a method for producing an enamel glaze that has excellent adhesion. (Prior art and its problems) Stainless steel is rust resistant, highly corrosion resistant, and retains its shine for a long time, so it is used for architectural interior and exterior walls, kitchen products,
It is used in many areas such as bathtubs, wash basins, and vehicles. However, while stainless steel has its advantages, it is also susceptible to scratch rust, crevice corrosion caused by contact between dissimilar metals, dirt, and dirt.
It has disadvantages such as being easily attacked by Cl ^- ions and not being able to be colored freely. Therefore, various methods of enameling stainless steel have been studied in the past as a way to further enhance the properties of stainless steel and at the same time eliminate these drawbacks, but the current situation is that nothing that is fully satisfactory has yet been achieved. . In other words, in order for the enamel glaze to have sufficient adhesion to the base metal, the base metal must be sufficiently oxidized at the firing temperature of the glaze, but stainless steel is considerably oxidized at the firing temperature of normal iron enamel glazes. It was thought that good adhesion could not be achieved because the glaze was stable and did not oxidize sufficiently for the glaze to react with the base material. Therefore, in order to obtain good adhesion between stainless steel and glaze, the surface of stainless steel must be roughened mechanically or chemically. Studies have been conducted on methods of introducing special metal oxides that promote or attack the oxidation of stainless steel into the frit that makes up the glaze. As a method, for example, by mechanically or chemically providing an uneven pattern with a concave depth of 80 to 400 μm and a roughness of the concave surface of 2 to 30 μm, the stainless steel and the glaze are brought into close contact. However, it is extremely difficult to industrially form a concave roughness of 2 to 30 μm and to confirm it. Also, stainless steel is heated in advance in an oxidizing atmosphere to form an oxide film on the surface, and then immersed in an aqueous solution containing divalent nickel ions to evenly adhere the nickel ions to the oxide film. A method for strengthening the adhesion of stainless steel and glaze has been disclosed (Japanese Patent Publication No. 55-30588), but this method has a problem in that it requires two steps to pre-treat the stainless steel. (It goes without saying that sufficient adhesion cannot be obtained by mere surface roughening methods such as sandblasting, shotblasting, and chemical etching methods commonly used in the enamel industry.) There is a method of introducing 1 to 3 wt% MoO ₃ into the frit component that can be fired at a relatively low temperature (Japanese Patent Publication No. 14819/1983), but this method involves baking a transparent glaze directly onto the stainless steel once. The result is a craft-like enamel product that shows the metallic luster pattern unique to stainless steel, and its frit composition is also very specific. Furthermore, an enamel frit with good adhesion to stainless steel has been disclosed, in which 5 to 30 wt% Fe ₂ O ₃ is introduced into a glass mainly composed of borosilicate, which does not contain a fluorine component. 52-810), this method introduces a large amount of Fe ₂ O ₃ during the production of the frit, which causes significant contamination of the glass melting furnace and kiln, making it extremely uneconomical for the production of the frit. Due to the large amount of Fe ₂ O ₃ component, Fe ₂ O ₃ precipitates in the glass matrix by repeated firing two to three times, and the glaze tends to devitrify, resulting in unstable adhesion. As described above, stainless steel enamel is not yet a completed technology, and is a technical field in which further improvement is desired. (Object of the Invention) The present invention aims to improve the problems of the conventional methods as described above, and provides an enamel glaze that has extremely good adhesion to stainless steel by a relatively simple means. (Structure of the Invention) When milling the frit, the present invention adds 0.05 to 5 of one or more of potassium tartrate, sodium tartrate, and potassium sodium tartrate to 100 parts by weight of the frit, in addition to the usual mill additives. There is a method for producing an enamel glaze for stainless steel, which is characterized by adding parts by weight. (Embodiment and operation) In the present invention, in addition to the usual mill additives such as clay, silica, borax, magnesium carbonate, magnesium oxide, potassium carbonate, sodium nitrite, and water, especially One or more of potassium tartrate, sodium tartrate, and potassium sodium tartrate is added as a mill additive at a ratio of 0.05 to 5 parts by weight per 100 parts by weight of the frit. As the frit, a normal stainless steel frit can be freely used and is not particularly limited. Any amount of conventional mill additives may also be used as desired. The glaze obtained by milling is applied to a degreased stainless steel surface, and when dried and fired at 700 to 900°C, it forms an enamel layer that has excellent adhesion to the stainless steel. Since the glaze of the present invention has very good adhesion, it is sufficient to simply degrease the stainless steel surface as a pre-treatment for glazing, and it is not necessary to use conventional mechanical or chemical means. There is no need to roughen the surface. It is not clear why the addition of sodium and potassium salts of tartaric acid as mill additives produces an enamel glaze that has good adhesion to the stainless steel surface, but no decrease in adhesion was observed even after repeated firing. I couldn't help it. In the present invention, the reason why the amount of one or more of sodium tartrate, potassium tartrate, and potassium sodium tartrate added is limited to 0.05 to 5 parts by weight per 100 parts by weight of frit.
This is because if it is less than 0.05 parts by weight, there is no effect of promoting adhesion at all, and if it exceeds 5 parts by weight, although adhesion is good, a large amount of bubbles will be present in the enamel layer, and the strength will drop significantly, making it impractical. The preferred amount is
It is 0.1 to 4 parts by weight. Next, the present invention will be explained in detail with reference to Examples. (Example) In carrying out the invention, the Enamel Technology Guidebook (August 20, 1980, published by the Japan Enamel Industry Association)
Page 55, No. 7 C frit shown in table 5-10 Frit composition for steel plate bottoming (Table 1), same book No. 56
Page, 5-11 Table No. 4 of titanium frit (Table 2), 5-
Table 12 Fluoride antimony tin white frit composition No.4
Four types of frits were prepared: (Table 3) and No. 1 (Table 4) of frits for 5-13 table stand gasuris.

【table】

【table】

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[Table] Example 1 Frit No. 7-C was milled using the milling composition shown in Table 5 to obtain glazes A and B.

[Table] Add 5g/10cm of glaze A and B to degreased stainless steel with a thickness of 0.8mm and a size of 10cm x 15cm.
The mixture was applied uniformly to a ratio of 15cm x 15cm (wet), dried and then baked at 820°C for 3.5 minutes. When the adhesion rate of the obtained test piece was measured using P, E, I adhesion testers, A was 85% and B was 91%. Example 2 Titanium frit No. 4 was milled according to the mill formulation shown in Table 6 to obtain titanium opalescent glazes C and D.

【table】

[Table] Thickness 0.6mm, size 30 with pre-treatment of degreasing only
A cm x 30 cm stainless steel plate was spray glazed with glazes C and D to give a weight of 40 g/30 cm x 30 cm, dried and then fired at 800°C for 3 minutes. The surface of the test piece obtained was very smooth and beautiful. When measured using a P, E, and I adhesion tester, all test pieces showed an adhesion rate of 90% or more. Example 3 Glazes E, F, and G were obtained by milling frit No. 1 for machine glazing and antimony frit No. 4 in Table 3 using the mill formulations shown in Table 7.

【table】

[Table] Thickness 1.2mm, size with pre-treatment of degreasing only
Glazes E, F, and G were sprayed onto a 20 cm x 20 cm stainless steel plate to give a weight of 20 g/20 cm x 20 cm (wet), and each was fired at 820°C for 4 minutes.
Among the test pieces obtained, only the one using glaze E had a somewhat large number of pores, but the other two types of test pieces both exhibited extremely smooth and beautiful surfaces. The adhesion rates of these three types of test pieces are P,
E, I, when measured with an adhesion tester, glaze E,
In order of FG, it was 100%, 89%, and 100%, which was extremely good. (Effects of the Invention) Since the present method involves simply adding tartrate as a mill additive, the manufacturing process is easy and economical. According to the glaze obtained in the present invention, there is no need to perform special pretreatment on stainless steel, and enameled stainless steel products with good adhesion can be obtained.

Claims (1)

[Claims] 1. When milling the frit, in addition to the usual mill additives, 0.05 to 5 parts by weight of one or more of potassium tartrate, sodium tartrate, and potassium sodium tartrate are added to 100 parts by weight of the frit. A method for producing enamel glaze for stainless steel.