Zinc stearate is mainly used as PVC stabilizer, as well as styrene resin, phenolic resin, amine resin lubricant and mold release agent. Below, tell us the production and processing technology of zinc stearate.

The industry generally USES four different methods to produce metal stearate salts, and each gives the product different characteristics.

1. Precipitation reaction

The fatty acid is first heated in water at a temperature above its melting point, with 20 times more water than the fatty acid, and then saponified with an equal mole of a strong alkali solution (such as sodium hydroxide solution, potassium hydroxide solution, ammonia solution, etc.). The resulting alkaline soap dissolves in water. Subsequently, the water-insoluble metal saponifier is prepared by adding a solution of metal salts (such as calcium chloride solution, aluminum sulfate solution).

2. Melting process

In the melting process, the metal oxide or metal hydroxide is heated with stearic acid above the melting point of the metal saponifier and is continuously stirred. Since the melting point of stearates is above 100°C, the water produced by the reaction escapes as steam. Therefore, there is no need to dry the metal salt of stearate (zinc stearate). From this process, we can produce spherical, flaky and powdered products. The high purity of the product is one of the main characteristics of the preparation of stearate metal salts by melt processing.

3. Direct reaction

The reaction of stearic acid with metal oxides, metal hydroxides, or carbonates takes place in large amounts of water and the reaction temperature rises gradually. So there are no by-products. Metal salts of stearate obtained by direct reaction are also fine powders with high purity. They are metal salts insoluble in water. Not all metallic stearate salts can be prepared in this way because the initial reactant may not be reactive enough. One advantage of this method is that the reaction is carried out at a certain pressure and at a high temperature (>100°C), which makes it possible to produce other types of metal salts of stearate, which are not normally produced by direct reaction processes.

4. AV process

AV process is a combination of direct reaction process and melting process. Metal oxides or metal hydroxides and fatty acids are heated in a patented process, with a small amount of water added to the reactor and heated at a temperature consistent with the saponification melting point. After the reactor pressure drops, the water added to the reaction and the water generated will be removed due to the reduced pressure. The AV process can produce granular or powdered products with high purity.

The above is the zinc stearate four production processes, the use of these processes can also produce calcium stearate, magnesium stearate, barium stearate, aluminum stearate, lead stearate and other stearate metal salts.