Process for stabilising halogenated vinyl resins

A process for stabilising a halogenated vinyl resin which comprises incorporating stannic chloride and a diorgano-tin dimercaptide into the resin, as stabilisers, the stannic chloride being present in an amount from 0.2% to 5% by weight based on the weight of the stabiliser mixture, the diorgano-tin dimercaptide being obtained by condensing

• a. a diorgano derivative of tetravalent tin selected from a dialkyl-tin oxide of formula R.sub.2 SnO, and a dichloro-dialkyl-stannane of formula R.sub.2 SnCl.sub.2, in which each R radical which may be identical or different, represents a straight or branched alkyl group with up to 10 carbon atoms;
• with
• b. a mono- or poly-mercaptan containing one or more ester groups, selected from a mercaptocarboxylic acid ester of the formula:
• HS -- X -- COOR'
• in which X represents a straight or branched alkylene group with up to 4 carbon atoms or a phenylene group, and R' represents an alkyl or alkenyl group with at most 10 carbon atoms, a cycloalkyl or cycloalkenyl group with 5 or 6 carbon atoms in the ring, or a phenylalkyl group, the alkyl part of which possesses 1 to 4 carbon atoms;
• and an .alpha.,.omega.-dimercapto-diester of the formula:
• HS -- X -- COO -- Y -- OCO -- X -- SH
• in which X is as defined above and Y represents either a straight or branched aliphatic divalent hydrocarbon radical with at most 10 carbon atoms, or a cycloaliphatic divalent hydrocarbon radical with 5 or 6 carbon atoms in the ring, said radical optionally containing one or two ethylenic and/or acetylenic bonds.