JPS6119578B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an enamel composition, and was made for the purpose of producing an enamel composition with excellent water resistance and chemical resistance. Conventionally, in the production of enameled steel plates, after the enameled steel plate is formed using a press or the like, pretreatments such as degreasing, pickling, nickel treatment, neutralization treatment, etc. are carried out to increase the adhesion between the steel plate and the glaze. This was done by sequentially drying, applying a pre-prepared glaze slip by spraying, dipping, etc., drying, and then firing at 800-850°C. In order to strengthen enameled wares, which require particularly strong durability and weather resistance, a lower glaze is applied to both sides of the enamel base steel plate, and an upper glaze is applied to the upper surface. The slip composition of the lower glaze and upper glaze is different depending on the role of each glaze. For example, the bottom glaze is a glass that has good adhesion to the steel plate, with no consideration given to chemical resistance, water resistance, etc., and the top glaze is a glass with colorful colors and excellent chemical resistance and hot water resistance, that is, fritz. The main components are usually milky titanium and borosilicate glass. For 100 parts by weight (hereinafter abbreviated as parts) of these upper and lower glaze frits,
For example, 5 to 7 parts of clay as mill additives,
Add 0.2 to 1.0 parts of electrolyte and 40 to 60 parts of water, grind in a ball mill, and use in a slip state. Here, the clay plays the role of a flotation agent for the glass powder, that is, a frit, an adhesion effector to the fabric, and a dry film strengthening agent, and the electrolyte mainly acts as a flotation aid, and in the case of the underglaze, Na ₂ B ₄ O ₇・10H ₂ O, NaNO _2, etc. are used, and for the top glaze, BaCl ₂ , MgCO ₃ , KCl,
NaAlO ₂ , MgCl ₂ , K ₂ CO ₃ and others are used.
In the case of slipping, the required performance cannot be obtained even if any of the above is lacking. By using a glaze that is carefully considered as described above, enamel has excellent characteristics such as strong adhesion to steel plates, colorful colors, excellent weather resistance, and a surface hardness that is harder than marble. And pan, bathtub,
Plumbing products such as wash basins, sanitary utensils, signboards,
It is used in a wide range of fields, including exterior and interior materials.
For vessels that require water resistance, such as bathtubs and washbowls, the top glaze is required to be water resistant. Erosion of enamel by water occurs from weak points in the inhomogeneous parts of the enamel. In other words, if the reaction between the glass for top glazing and mill additives such as clay on the enamel surface is insufficient, for example, if the additives such as glass or clay have poor reactivity, the firing conditions may be insufficient. If there is, non-uniform areas are likely to be formed. Regarding the former type of frit, the selection is limited in terms of color and other aspects, and even if good frit is used, it is difficult to improve the enamel corrosion resistance. Therefore, it would be good if the reaction between the frit and the clay could be ensured under the firing conditions, but if the firing is too long, yellowing of the color or deformation of the dough may occur due to rutile transition of the titanium crystals. Therefore, in order to improve hot water resistance, it is necessary to consider a completely different mill formulation. The present invention was made in view of the above-mentioned circumstances, and provides an enamel composition that eliminates the conventional drawbacks. The enamel composition according to the present invention is characterized in that its main components are a frit for enamel, methylcellulose, a specific metal carbonate, particulate silica, and water. The present invention will be explained in detail below. As mentioned earlier, enamel with poor water resistance is caused by uneven surfaces. In other words, it would be most ideal if the frit itself could be directly glazed, but it is impossible to powder-coat the frit itself to give it an enamel finish. Therefore, there is no choice but to mix the glass powder with water to form a slip and apply the glaze, but in this case it is necessary to carry out a treatment to keep the frit in a uniformly dispersed state, which would result in the mill mix as described above. There are drawbacks. However, if instead of using clay as a mill additive, it would be completely burned out during the firing process, the result would be the same as using only frit. In other words, you can choose an organic flotation agent, but organic materials that leave firing residue or have a high decomposition temperature that delays the decomposition to the temperature at which the glass melts will create large bubbles in the enamel layer. This causes pinholes, etc. Therefore, the conditions for the organic floating agent are as follows in the enamel firing process:
It must be able to decompose at low temperatures without leaving any residue, and decompose and disappear before the glass melts. Therefore, the present inventors investigated various organic flotation agents, and as a result selected methylcellulose as a flotation agent with a low decomposition temperature and no residue, and completed the present invention. There are various types of methylcellulose with different degrees of polymerization, but all of them reach 100% by 600℃.
decomposes and the decomposition temperatures are exactly the same. Thus, any type of methylcellulose can be used. The amount of methylcellulose to be used is preferably 0.05 to 2.0 parts per 100 parts of frit, although this is not intended to be limiting. If it is less than 0.05 parts, the floating effect will not be sufficient, and if it exceeds 2.0 parts, the viscosity of the slip will become too large and bubbles will easily form in the enamel, probably because the decomposition temperature shifts. When using methylcellulose, a carbonate of a specific metal is used as a flotation aid. Examples of this include potassium carbonate, sodium carbonate, and magnesium carbonate, and one or more of these may be used. These materials are advantageous because they melt into the glass without leaving bubbles in the enamel layer and do not create non-uniform areas on the surface. Further, the amount of carbonate of these metals used is preferably 0.25 to 1.0 parts. If the lower limit of this range is not reached, methylcellulose is not sufficiently dispersed and spots appear on the glazed surface, which is not preferable. On the other hand, if it exceeds the upper limit, it is not preferable because it will worsen the characteristics of the enamel. Furthermore, by using fine particle silica in combination, glazing properties can be further improved. The fine particles of silicic acid are colloidal and react with the frit (glass) during firing, improving the acid resistance of the enamel. However, excessive addition will actually worsen the glazing properties and reduce the water resistance of the enamel. Therefore, it is preferable to limit the amount used to 1.0 parts or less per 100 parts of frit. Each of the raw materials described above is milled with an appropriate amount of water to form a slip. The amount of water is fritted
40 to 70 copies per 100 copies. Ultimately, the most preferred mill formulation provided in the present invention is as follows. Frit 100 parts Methyl cellulose 0.05-2.0 Specified metal carbonate 0.25-1.0 Particulate silica 0-1.0 Water 40-70 When actually applying the glaze using a slip of 40 to 70, for example, use the following procedure. In other words, weigh out the amount of methylcellulose that should be added, and add 60
Add ~100 °C hot water to completely wet the methylcellulose. Next, add cold water and, if necessary, ice to bring the temperature below 20°C. In this way, methylcellulose is made into a completely clean aqueous solution. Alternatively, methylcellulose may be moistened with a small amount of a water-soluble organic solvent, such as alcohol or propylene glycol, and then cold water is added. Next, a specified amount of frit, electrolyte, and particulate silica are added to the above aqueous solution together with water into a pot mill, and the mixture is mixed and pulverized. The amount of methylcellulose, the amount of carbonate, and the amount of water can be increased or decreased depending on the slip properties required. After this, the glaze is applied by spraying or dipping on the underglazed fabric as usual, then dried and fired. In summary, the enamel composition according to the present invention mainly contains a frit for enamel, methylcellulose, particulate silica, water, and one or more metal carbonates selected from the group consisting of potassium carbonate, sodium carbonate, and magnesium carbonate. Since it is a component, there are no inhomogeneous parts, so it is possible to provide enamel with excellent water resistance, acid resistance, and alkali resistance, and with a significantly improved enamel life. Furthermore, since no clay or the like is used, the same quality can be maintained at a considerably lower firing temperature, which has the effect of reducing firing costs and reducing deformation of the green steel plate. Example As the lower glaze formulation, lower glaze formulation [H] manufactured by Nippon Fellow Co., Ltd. was used. The upper glaze composition shown in Table 1 was obtained. Table 1 shows the number of parts of each additive per 100 parts of frit. The frit is made by Nippon Fellow Co., Ltd.
T-7812, methylcellulose manufactured by Matsumoto Yushi Co., Ltd., product numbers Marporose (M-2000) and Marporose (M-10000), and Aerosil #200 as fine powder silica were used. Slip No. 1 represents a conventional example. The characteristics of the slip obtained with the top glaze composition shown in Table 1 were as shown in Table 2.

【table】

【table】

[Table] The slip was measured as follows. (1) Viscosity was measured using a BM type viscometer. (2) Alkali resistance: Na ₂ CO ₃ at a concentration of 10g/100ml
A spot test was performed using an aqueous solution for 15 minutes at room temperature. Surface evaluation was performed according to the standard of JIS R4301-1971. (3) Surface gloss: This is a value measured using a gloss meter. (4) Surface roughness: 10m/m in the center of the test piece
Roughness was measured at a magnification of 10,000 times and expressed as its maximum amplitude. A Kosaka type surface roughness meter was used as the device.

【table】

【table】

【table】

Claims (1)

[Claims] 1. Frit for enamel 100 parts by weight Methyl cellulose 0.05 to 2.0 parts by weight Metal carbonate 0.25 to 1.0 parts by weight Water 40 to 70 parts by weight Further, 1 part by weight or less of fine particle silica is added to the enamel composition. An enamel composition characterized by: