It is understood that stearic acid is a white flake, bead or block solid at room temperature. It is composed of saturated fatty acids mainly C16 and C18. It is insoluble in water, slightly soluble in benzene and carbon disulfide, easily soluble in hot ethanol, non-toxic and tasteless, and has the general chemical properties of organic carboxylic acids. Stearic acid is a fatty acid widely found in nature. Almost all oils contain stearic acid in varying amounts. The content is higher in animal fats. For example, the content in butter can reach 24%, and in vegetable oils it is less. , tea oil is 0.8%, palm oil is 6%, but the content of cocoa butter is as high as 34%. There are two main production methods for industrial stearic acid: fractionation method and pressing method. A decomposing agent is added to the hardened oil, and then it is hydrolyzed to obtain crude fatty acids, which are then washed, distilled, and decolorized to obtain the finished product, while glycerol is produced as a by-product.
Stearic acid is widely used in the plastics industry:
Stearic acid has the functions of lubricant, plasticizer, dispersant, stabilizing agent in plastic fillers With the multiple functions of agents, antioxidants and flame retardants, it can improve the processing performance, physical properties, weather resistance, corrosion resistance and combustion performance of plastics, and improve the quality and performance of plastic products. For example, stearic acid can be used as a lubricant for plastic fillers. During the plastic processing process, the friction between the filler and the plastic matrix will cause the generation of heat, thereby affecting the processing performance of the plastic. The addition of stearic acid can reduce the friction between the filler and the matrix, reduce the heat generation of the plastic, and improve the fluidity and processability of the plastic.
Stearic acid is a PVC heat stabilizer with good lubricity and good light and heat stabilization. In plastic PVC pipes, stearic acid helps prevent “scorching” during processing. It is an effective heat stabilizer added in PVC film processing and can prevent the finished film from being exposed to sulfides. Color Changing Rubber Industry Stearic acid plays an important role in the synthesis and processing of rubber.
When stearic acid is used in modified plastics, attention should be paid to the following aspects:
1. The processing temperature should not exceed 230 degrees, because stearic acid flashes The point is 226 degrees. If it is higher than the flash point, the thermal stability of stearic acid will be reduced, which will lead to the decomposition and degradation of the material;
2. Since stearic acid is a small molecule substance, it is in plastics It is mainly used for internal lubrication. The general addition amount is 0.2-0.5%, and the addition amount is less than 1%. It should not be too large, otherwise it is easy to bloom. During the use of the product, surface precipitation problems will occur, thus affecting the appearance of the product;
3. Stearic acid can be selected from different grades according to the C18 content. The higher the C18 content, the higher the stability and the less likely it is to precipitate.
4. There are also unsaturated double bonds in stearic acid, so the color of some materials will turn yellow when used. This is mainly caused by the unsaturated double bonds in stearic acid. This can be achieved by adding After melting at high temperature, its pH value and color changes are detected to determine the effect of the thermal stability of the material.
微信扫一扫打赏
