Stearic acid is a fatty acid that is widely found in nature. , it 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, and is non-toxic and tasteless.
Stearic acid is widely used in the manufacture of PVC plastic pipes, plates, profiles, and films. It 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 added during PVC film processing. An effective heat stabilizer that also protects against discoloration of finished films caused by exposure to sulfides.
In addition, stearic acid is used as a lubricant in hard PVC processing. The dosage is generally 0.2-0.5PHR, and has the effect of preventing chromatography scaling, but Excessive dosage may result in blooming. The function of PVC lubricant is to improve the fluidity of resin and the demoulding property of products in plastic processing, and to prevent defects caused by adhesion in the machine or mold.
Stearic acid is a solid plasticizer in PE, PET and PVC. It is suitable for high-temperature screw extrusion processes. It also has self-lubricating and Mold release function. Add too little stearic acid to PVC. PVC is brittle and has an uneven surface that is prone to silver cracking and stress cracking. If too much is added, the mechanical strength and tensile strength of the PVC discharged material will be greatly reduced, and the water resistance will be reduced (stearic acid can be slowly dissolved and emulsified in warm water). It depends on what kind of products your PVC is used for. Different products have different requirements for stearic acid. In addition, stearic acid and magnesium stearate have opposite effects. Adding more stearic acid makes it softer, while adding more magnesium stearate becomes extremely hard and brittle.
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