Calcium stearate and zinc stearate are both produced from polyolefins important additives. It is mainly used to neutralize chloride ions in Ziegler-Natta PE resin powder and prevent its corrosive effect on processing equipment components. At the same time, these two additives can also improve the whiteness of PE particles and the lubricity of molding processing. In recent years, these two additives have begun to be added synergistically to improve the overall performance of PE. Since these two additives are the lowest priced among the additive systems used in PE production, their dosage can be increased to improve their performance and save costs.
But it is pointed out that although zinc stearate and calcium stearate are somewhat similar, they are specific Functional usesThere are differences in uses and fields, as follows:
1. First of all, calcium stearate and Although zinc stearate can be used as a lubricant and stabilizer, calcium stearate is mostly used in a variety of plastic processing, while zinc stearate is mainly used in styrene resin, phenolic resin, and amino resin. . Most PE raw materials contain zinc stearate. But there is a big difference in content. As a neutralizing agent for catalysts used in PE synthesis, zinc stearate is a necessary additive for PE.
2. Although both can be used as PVC heat stabilizers, calcium stearate is mainly used in polyvinyl chloride, while zinc stearate is mostly used in On PVC, to inhibit initial coloring and lubrication, there is no sulfide pollution, but the effect is limited, and it needs to be used in conjunction with stabilizers such as calcium soap and barium soap.
3. Both calcium stearate and zinc stearate can be used as softeners in rubber processing, but calcium stearate can also be used as a plasticizer. , it does not affect the vulcanization effect of rubber on the basis of softening, but zinc stearate can be used as a vulcanization activator and softener.
4. Calcium stearate has a wider range of functions. It can not only increase the gelation speed in hard products, but also can be used in polyethylene and polypropylene. Halogen absorber eliminates the impact of residual catalyst on color and stability. It can also be used as a lubricant for polyolefin fibers and molding compounds, a waterproofing agent for textiles, a flattening agent for paints, a thickening agent for grease, and a lubricant in the manufacture of plastic records. Plasticizers, etc.
5. Calcium stearate is used as a co-stabilizer in polyacetal resin and its acid capture ability can neutralize the formaldehyde produced during oxidation. of formic acid. The addition of stearic acid metal salt improves melt stability in composite extrusion. The relative decrease in volume melt index can be attributed to the reorganization of macromolecular radicals. The reorganization of macromolecular radicals leads to the formation of branched chains and gels. Formulations containing calcium stearate showed better stability against “free radical recombination” than formulas containing zinc stearate.
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