JPH0310585B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an enamel glaze composition. Structure of conventional examples and their problems In general, the enameling treatment of steel plates involves mixing clay, colloidal silica or bentonite as a suspending agent, NaNO ₂ , NaAlO ₂ , KCl or MgCO ₃ as a stopper, and water in the enamel frit. Mill pulled,
The resulting slip is pickled, glazed onto a nickel-treated steel plate, and fired. Among the defects that appear on the enamel surface processed in this way, defects caused by slips include tearing, cracks, hair lines, sponge bubbles, and bumper heads. These defects are caused by boric acid and alkaline content eluted from the enamel frit, and may vary depending on the slip manufacturing conditions, slip storage conditions, enamel film thickness, drying method, handling of dried utensils, and degree of firing. It is something that is caused by something. Among these defects, tearing, cracking, and hairlines occur relatively early. Tearing, cracking, etc. were prevented by adding a small amount of urea to the slip after milling. However, with the method of adding urea, there is no problem with frit slips that are baked at high temperatures (approximately 800℃) and elute relatively little alkali, etc., but are baked at low temperatures (approximately 700℃ or less) that elute a large amount of alkalis, etc.
In the slip of a type of frit, urea or urea decomposition products are adsorbed onto clay, colloidal silica, or bentonite particles in an accelerated manner by the alkali etc. eluted from the frit, and the adsorbed urea or urea decomposition products are absorbed at temperatures near the calcination temperature. Since it desorbs at high temperatures, spongy bubbles are generated on the enamel surface. In other words, when we examined the case where a frit slip with a large amount of alkali elution was stored at 35°C, we found that if it did not contain urea,
Tearing, cracks, and hair lines appear on the enamel coating after about 4 hours, and spongy foam appears after 10 days or more. Furthermore, when urea is contained, sponge foam is generated after about 6 hours, and tearing or cracking occurs after 30 hours. Therefore, in low-temperature baking type enamels (hereinafter referred to as low-melting enamels) that often elute alkali, etc., urea can be added during milling or even after milling, but in summer The temperature when pulling and storing the slip is high (35℃).
(temperature below 20℃)
The drawback was that I had to do it. In general, low-melting hollow frits elute more alkali, etc. than high-temperature types, and their fluidity (at the firing temperature) is low and repairability is poor, so tearing, cracking, etc. are more likely to occur. When using urea as mentioned above, slip temperature must be carefully controlled. Therefore, a tearing and cracking preventive agent to replace urea was needed. OBJECTS OF THE INVENTION An object of the present invention is to provide an enamel glaze composition that does not cause early formation of tearing, cracking, hair lines, or sponge bubbles even in low-melting enamel frits that elute a large amount of alkali or the like. Structure of the Invention The enamel glaze composition of the present invention basically contains enamel frit as a main component and terephthalic acid amide as an agent for preventing tearing and cracking. As a specific composition of the enamel glaze composition of the present invention, 0.1 to 2 parts by weight of terephthalic acid amide is preferably used per 100 parts by weight of the enamel frit. If the composition contains more than 2 parts by weight of terephthalic acid amide per 100 parts by weight of the hollow frit, the effect of preventing tearing, cracking, etc. is great, but in the summer (about 35°C), alkali etc. When using a hollow frit with a very large amount of elution,
Sponge foam appears relatively early. On the other hand, if the content is less than 0.1 part by weight, if a frit is used in the summer where a large amount of alkali elutes, etc.,
Especially when the glaze is thick (approximately 200 μm or more), tearing, cracking, and hair lines are likely to occur. Terephthalic acid amide can be added to the glaze composition by mill addition or after milling, but in the case of mill addition, the milling time is shortened (1
time) and it is desirable that the temperature in the mill does not exceed 30°C. It is believed that urea and terephthalic acid amide act as a binder between the hollow frit particles and prevent tearing, cracking, and hairlines. In addition to terephthalic acid amide, the present inventors have discovered amide compounds such as phthaldiamide, hexamethylenetetramine, other gums such as carboxymethyl cellulose, gum tragacanth, gum arabic, polyvinyl alcohol, polyethylene oxide,
I tried using many types of pulp, etc., but some had no effect on preventing tearing and cracking, and even though they were effective, they generated spongy foam. Next, the enamel glaze composition of the present invention is produced, for example, as follows. First, make the enamel frit. For that,
The raw materials for each component are mixed according to the desired frit composition. After thorough dry mixing, heat and melt at 1100-1300°C. Since the heating temperature and time change the composition ratio of the final frit, it is necessary to carefully control the heating temperature and time. It is important to allow vitrification to proceed for 20 to 40 minutes after dissolving the raw materials, stirring as necessary. If the melting temperature is maintained for too long, the alkaline components will sublimate, so avoid keeping it too long. After melting, the glass is placed in water and rapidly cooled. When this is dried, a hollow frit is obtained. Enamel frit 100 obtained in this way
3 to 9 parts by weight of clay, colloidal silica, etc. as a suspending agent, and 1 part by weight of sodium nitrite, magnesium carbonate, sodium aluminate, etc. as a stopping agent.
40 to 70 parts by volume of water are added to 10 parts by weight or less of pigment, other silica powder, and hydrated borax, and the mixture is ground and mixed using a ball mill or the like. Here, terephthalic acid amide is
Mill blending is also possible, but when the temperature exceeds 30°C, mix in the slip after milling and mix with stirring. Note that the amount of terephthalic acid amide added is 0.1 to 2 parts by weight. Regarding the particle size of the slip, the 200 mesh residue in 50 ml of the slip is 1 to 7 g when spray glazed, and 15 g or less when dip glazed, and preferably as coarse as possible to reduce elution of frit components. The enamel glaze composition thus obtained is sprayed or dip-glazed onto steel utensils that have been pickled and electroless nickel-plated, dried, and fired (for example, at 710°C for 3 minutes in the case of low-melting enamel frits). ) to form an enamel film. Description of Examples Next, Examples will be described together with Comparative Examples. [Manufacture of low-melting hollow frit] First, the raw materials shown in Table 1 below were blended in the proportions shown in the same table, and the mixture for low-melting hollow frit 1,
I made 2. Then, this mixture was mixed and placed in an alumina crucible, melted and clarified at 1100 to 1300°C, and then poured into water and cooled. As a result, the low melting hollow frit G shown in Table 2
-1 and G-2 were obtained.

【table】

【table】

[Manufacture of hollow slips]

After drying and coarsely pulverizing the low-melting hollow frits G-1 and G-2 obtained as described above, mill additives shown in Table 3 below were added in the proportions shown in the table. Next, add 3 kg of frit to the mixture shown in Table 3.
The mixture was placed in a No. 10 pot mill and mixed and pulverized at approximately 75 r.p.m. for 1 hour. At this time, the mill temperature is 30
The particle size of the slip (200 mesh residue of 50 c.c.) was adjusted to 1 to 7 g. The condition of the enamel coating on the slips was checked immediately after being taken out of the mill, and the slips were stored in a constant temperature bath or constant temperature water bath at the storage temperature shown in Table 3, and the condition of the enamel coating was checked periodically.

[Table] Enamel processing was performed under the following conditions. Base material; Steel type: SPP material Dimensions: 100mm x 100mm x 0.6mm Pretreatment: Pickling loss value 400-500mg/dm ² Nickel adhesion amount 14-20mg/dm ² Glazing: Spray method Enamel film thickness: 150-180μm Drying method Far-infrared drying and firing conditions: The time was 3 minutes and 40 seconds, and the temperatures are shown in Table 4. Table 4 shows the results of checking the pot life under the above conditions. The effect of terephthalic acid amide on Frit G-1 was compared to the effect of no anti-tearing agent and to that of urea, phthaldiamide, and hexamethylenetetramine. As shown in Table 4, when the slip is refrigerated, there is no practical problem even if no inhibitor is added.

[Table] However, if slips are stored at room temperature around 35°C, for example in the summer, the slips will become unusable in about 4 hours unless a tearing/crack preventive agent is added. Therefore, as inhibitors, urea, phthaldiamide,
Even if hexamethylenetetramine is tried, spongy foam appears within 6 hours. Therefore, these inhibitors are also not practical. In comparison, when terephthalic acid amide is added, the occurrence of tearing and cracking is not delayed, and the occurrence of sponge foam is also lower than that of urea.
It takes a considerable amount of time, and in the summer, you can get something that can be used for 1 to 2 days without refrigeration. Furthermore, when silica powder is added (Example 5), it acts as an antifoaming agent and can further delay the generation of sponge foam. In Example 6 and Comparative Examples 8 and 9, the pot life characteristics of the slip of Frit G-2 were shown. As shown in Table 4, even low-melting hollow frits have good fluidity and are sufficiently usable for practical use without the addition of tearing/cracking inhibitors. Even in the case of Fritz G-2, an inhibitor is added if there is a risk of tearing or cracking occurring during handling. In this case as well, terephthalamic acid generates sponge foam more slowly than urea. Effects of the Invention As described above, the enamel glaze composition containing terephthalic acid amide of the present invention is less likely to generate tearing, cracking, and sponge bubbles. In particular, when using a low-melting hollow frit with poor fluidity and a large amount of alkali elution,
It is possible to provide an enamel glaze composition that can be sufficiently used even in summer. Mill addition is also possible. Although low-melting enamel has many features such as less deformation, strength deterioration, pinholes and cracks, and is resource- and energy-saving, it also has a large amount of B ₂ O ₃ and alkali components leached from the frit. Therefore, the pot life of the slip was short, which was a major problem in putting it into practical use, but the present invention can greatly bring it closer to practical use.

Claims (1)

[Scope of Claims] 1. An enamel glaze composition comprising enamel frit as a main component and terephthalic acid amide as a tearing and crack preventing agent. 2. The enamel glaze composition according to claim 1, containing 0.1 to 2 parts by weight of terephthalic acid amide based on 100 parts by weight of the enamel frit.