The stearic acid we often talk about is actually called stearic acid, and the salt it forms with metal ions is called stearate. There are three common ones: zinc stearate, calcium stearate and barium stearate. Today, let’s talk about the characteristics, uses, and preparation methods of these three strategies.
Zinc stearate
Zinc stearate is a white powder. It is insoluble in water and soluble in hot alcohol, benzene, toluene, turpentine, and other organic solvents. When encountering acid, it decomposes into stearic acid and corresponding salts. It has various uses and can be mainly used as a stabilizer, lubricant, grease, accelerator, and thickener to facilitate storage and transportation.
There are two methods for producing zinc stearate: water and melting. Generally speaking, zinc stearate produced by the water method is acidic, and the melting method is alkaline.
Water method:Â (also known as wet method), under the condition of water as the medium, add a catalyst, control a certain temperature and pressure, then add metal hydroxide, replace the metal ions on the catalyst through the catalyst, and then replace it through the catalyst itself to stearic acid to achieve the purpose of generating metal salts.
Source of acidity:Â In water-based production, there is usually a slight excess of stearic acid, so the finished product is acidic after the reaction.
Melting method: (also called dry method) directly add metal oxides to molten stearic acid, control a certain temperature, pressure and stirring speed, and obtain stearate through reaction.
Source of alkalinity:Â Due to the presence of a catalyst, the general reaction result of products produced by the dry process can be completely reacted. The metal oxide is slightly excessive, so the product appears alkaline when tested.
Calcium stearate
In appearance, calcium stearate is a fine white powder, easily soluble in hot pyridine, slightly soluble in hot alcohol, hot vegetable oil, and mineral oil, and insoluble in water, ether, chloroform, acetone, and cold alcohol. Calcium stearate is often used as a non-toxic heat stabilizer for polyvinyl chloride, food packaging films, medical equipment and other soft products that require non-toxic; because of its good non-toxic heat stabilizer and lubricant, it is also used in adhesives, Flattening agent and water-resistant agent for coatings are broadly used in chemical production processes such as plastics and rubber.
There are many documented methods for preparing calcium stearate. The common metathesis method is as follows: Dissolve stearic acid in 20 times the mass of hot water, add saturated caustic soda solution, and perform a saponification reaction at about 75°C. , generate a dilute sodium stearate solution. Then, add the calcium chloride solution with a 1074kg/m3 content to the sodium stearate solution, conduct a metathesis reaction at about 65°C, and the calcium stearate product precipitates out. Then, filter, wash, and dry at about 90°C to obtain the finished product.
Barium stearate
Barium stearate is a white or slightly yellow powder crystal, which is hygroscopic in the air, soluble in hot ethanol, benzene, toluene and other non-polar solvents, but insoluble in water.
Barium stearate is a good heat stabilizer in polyvinyl chloride and vinyl chloride copolymer, with good long-term heat resistance and lubricant. The stabilizing effect is greater than calcium stearate but not as good as lead stearate. In some industrial fields, it can be used as a high-temperature release agent and high-temperature lubricant. At the same time, it can also be used for transparent films, sheets, artificial leather, rigid plates and pipes, etc.
For example, it is used with zinc soap in the formulation of sulfur-resistant artificial leather. It is often used with salt-based lead salt and lead soap in pipes and cables. If used together with cadmium soap, zinc soap or epoxy compounds, the electrical properties of the product can be effectively improved.
The method of synthesizing barium stearate is relatively simple. Add stearic acid into the reaction kettle, and add 20 times the mass of hot water to dissolve it while stirring. Add caustic soda at 80 degrees Celsius to generate a dilute sodium stearate solution. When the temperature of the reaction solution decreases to 70 degrees Celsius, a barium chloride solution is added to cause a metathesis reaction. Barium stearate is precipitated in the form of a precipitate. The finished product of barium stearate can be obtained by filtering, washing, and drying the precipitate.
Supplier
TRUNNANO is a supplier of Zinc stearate with over 12 years experience in nano-building energy conservation and nanotechnology development. It accepts payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea. If you are looking for high-quality Zinc stearate, please feel free to contact us and send an inquiry.