NL251261A - - Google Patents

Abstract

The process of the parent Specification is modified in that before the extrusion of filaments the isotactic polypropylene is subjected to thermal degradation by admixture with a sulphur compound which gives rise to thiyl radicals, e.g. thiphenols, mercaptans, thioureas, thioacids and the salts thereof, disulphides and polysulphides. Compounds specified include thio-b -naphthol, pentachlorothiophenol, 4,41-thio-bis(3-methyl-6-tert. butyl phenol), 2,21-thio-bis(3-methyl-6-tert. butyl phenol), 4,41-thio-bis(2-methyl-5-tert. butyl phenol), 2,21-thio-bis(6-methyl-3,5-tert. butyl phenol), dodecylmercaptan, mercaptobenzimidazole, dinonyldithiophosphoric acid and its salts, mercaptobenzthiazole bisulphide, di-isopropyldithiophosphoryl disulphide, diphenyl disulphide, di-obenzamidodiphenyldisulphide, 2,21-bis(N-phenylbenzamido) phenyl disulphide, diaroyl disulphides, diaroyl polysulphides and amine polysulphides, e.g. 4:41-dithiomorpholine and sulphur compounds having weak bonds between sulphur and another atom, e.g. dialkyl monosulphides, diaryl monosulphides, diaralkyl monosulphides, diacyl monosulphides, thio phosphoryl monosulphides, dithiocarbamoyl monosulphides, benzthiazole sulphenamides, diphosphoryl sulphenamides, tetramethylthiur-ammonosulphide and alkyl thioamines. The sulphur compound may also protect the polypropylene against the action of light, weathering, oxidation and heat up to about 150 DEG C., and may be used in association with a sulphur-free compound having a stabilizing action alone or providing a synergistic action with the sulphur compound. Preferably, less than 2% (by weight of the polypropylene) of the sulphur compound is used. The sulphur-free compound may be an ultra-violet light absorber (e.g. carbon black), an antioxidant, a free-radical inhibitor or a metal-ion inhibitor.