Can technical grade sodium tripolyphosphate improve the flow instability of ceramic glaze?
Ceramic production technology has been explored and precipitated since ancient times. Glaze is an important raw material in ceramic production, and the performance of glaze slurry is also a process link prone to problems. The unstable flow rate of ceramic glaze can not be solved by raw material formula alone. Combined with the development of modern science and technology, the stability of glaze performance can be reasonably adjusted and improved by additives such as technical grade sodium tripolyphosphate.
Such problems are often encountered in production: after the glaze slurry (especially raw glaze) is stored for a period of time, the flow rate will be unstable like tofu flower, commonly known as poor thixotropy. In serious cases, bell jar glaze spraying can not be implemented at all.
Sodium tripolyphosphate is also called water reducing agent and degumming agent. Technical grade sodium tripolyphosphate used in ceramic industry has obvious degumming effect on ceramic slurry, especially ceramic glaze. Its function can dilute the glaze slurry and improve the fluidity of the slurry under the condition of low moisture. At the same viscosity, the glaze strength and water retention of sodium tripolyphosphate are better than ordinary degumming agents, and the glaze slurry is not easy to deteriorate.
Some tests show that in the once fired frit glaze, simazhong sticks c50g methyl, the addition amount is 0.12%, and the sodium tripolyphosphate of Chuandong Chemical is 0.25%. The glaze slurry can remain unchanged for one week, the specific gravity flow rate is basically stable within one week, and the semi raw material glaze can be maintained for more than half a month. In the secondary firing frit glaze, Sima low viscosity c25g or c12g methyl is selected, the addition amount is 0.08% and sodium tripolyphosphate of Chuandong Chemical is 0.16%, which has no problem for one week, and is especially suitable for online roller printing process.
The appropriate amount of additives can also increase the glaze strength and reduce the damage to the glaze caused by external forces such as wire mesh scraper and edge washing. For antique bricks with polishing and brushing process, since the polishing and brushing grinding head has a large force on the glaze, the glaze must ensure sufficient strength to prevent damage and facilitate polishing and brushing.
Therefore, under the condition of ensuring that the glaze slurry does not precipitate, the type and amount of technical grade sodium tripolyphosphate also need to be determined through many experiments to maintain a high specific gravity and good fluidity.