The compounds formed by different lengths of fatty acids with metals are called metal soaps.
They are used as auxiliary stabilizer and inner/outer slider in PVC formulas. Metal soaps can be used individually in PVC formulas or also in synergistic combinations (Ca/Zn, Ba/Zn etc.). The most commonly known types are Al, Ba, Ca, PB, Mg or Zn soaps of stearic, lauric or benzoic acid.
Calcium stearate, barium stearate and laurates of these metals are also co-stabilizers which increase the heat stability and react with HCl, which is released by breaking out of the PVC structure and showing their effects by forming CaCl2 salt.
Zinc stearate and zinc laurate, which are used as external lubricants in PVC formulations, also have the first coloration-reducing effect. In the process, they are co-stabilizers that react with HCl, which is released by breaking out of the PVC structure, to form the ZnCl2 salt.