What are the roles of calcium stearate in coated sand?

I. Introduction to Calcium Stearate:

Calcium stearate is a white powder, insoluble in water, and decomposes into stearic acid and the corresponding calcium salt in the presence of strong acids. It is hygroscopic. This product has a very mild, pungent odor and high hardness. Its viscosity decreases significantly at temperatures below 200°C. Calcium stearate is widely used in the manufacture of PVC plastic pipes, sheets, profiles, and films.

II. The specific functions of calcium stearate in coated sand are as follows

1. Calcium stearate is uniformly distributed in the coated sand. At the core-making temperature, the resin and calcium stearate soften and melt, forming an interpenetrating network that increases the resin's flexibility and shell flexibility, thus leading to increased thermal toughness. The lubricating properties of calcium stearate improve the fluidity of the coated sand, increasing the compactness of the sand core and thus improving the core strength.

2. The melting point of calcium stearate is 60-80 degrees Celsius higher than that of resin. After heating, calcium stearate softens later than resin. The unmelted calcium stearate dispersed in the sand acts as a skeleton within a certain range. During the resin softening period, it prevents the sedimentation of sand gravel, reducing the tendency for the formation and expansion of voids in the sand core; it also helps to increase the melting point of the coated sand.

3. Calcium stearate also improves the thermal cracking resistance of coated sand. The main cause of thermal cracking in coated sand is thermal stress generated by thermal expansion. As the amount of calcium stearate increases, the thermal cracking time is gradually delayed. This is because the melting point of calcium stearate is higher than that of resin, and its increase is beneficial to improving the thermoplasticity of the sand core, thereby relaxing the thermal stress in the sand core.

Although the amount of calcium stearate added to coated sand is small, its effect is very significant. It can prevent the coated sand from agglomerating, improve fluidity, and improve resistance to peeling and demolding.

Jiangsu Rongsheng has many years of import and export experience and possesses its own highly mature calcium stearate technology and production line.Our calcium stearate equipment has very prominent advantages.