Synthesis, property and heat stability for polyvinyl chlorids of antimony tris (mercaptoacid ester)

Abstract

Antimony mercapide heat stabilizer for polyvinyl chloride is synthesized from antimony trioxide and mercaptocarboxylic acid esters, HS(CH₂)_nCOOi-C₈H₁₇(n=1–2) at 100–115°C in the presence of 0.5%–1% an organic acid catalyst. Some physicochemical constants of the compounds, such as density and refractive index, are determined. The complexes are hydrolabil in aqueous solutions and the bond of Sb-S is weaker than that of Sb-O. The forming bond property of antimony tris (mercaptoacid ester) has been elucidated by measurement of infrared spectra in comparison with mercapto carboxylic acid esters. The polyvinyl chloride resins containing antimony mercaptide heat stabilizers, do not darken at elevated temperatures and exhibit a high degree of stability. It is proposed that mercaptocarboxylic acid ester free radicals can esterify PVC microradicals at carbon atoms with upaired electrons.

Keywords

antimony tris (mercaptoacid ester) / synthesis / heat stabilizer / polyvinyl chloride