Process for stabilizing the polyolefins against the effects of degradation of the light and heat

摘要

Dithiophosphinate salts of the general formula FORM:1037017/C2/1 wherein R and R1 are individually alkyl of 2-18 carbon atoms, cycloalkyl of 5-6 carbon atoms, monocyclic aralkyl of 7 to 10 carbon atoms or cyanoethyl; and Me is a cation of a metal of Zn, Ni, Pb, Cd, Ca, Ba, Mg, Cu, Sn or Mn characterized by reacting a secondary phosphine of the formula RR1PH wherein R and R1 are as hereinbefore defined with sulphur, and ammonium hydroxide to form the corresponding ammonium salt which is reacted with an appropriate basic metallic reagent to form the metal salt. The invention also comprises "per se" the metal salts of dicyclohexyldithiophosphinic acid wherein the metal is Zn, Pb, Cd, Sn or Mn; such salts being obtainable as above. Preferred R and R1 groups are C4-C12 alkyl, cyclohexyl, phenethyl, b -methylphenethyl and a -methylbenzyl groups. Examples are given for the preparation of zinc, lead, cadmium, manganese and tin dicyclohexyldithiophosphinates; zinc di-n-octyldithiophosphinates, and zinc di-t-octyldithiophosphinate. The products are useful for stabilizing polyolefins against the deteriorative action of heat and light (see Division C3).ALSO:A composition having stability against the deteriorating effects of heat and light, comprises a polyolefin and from 0.01 to 5.0% by weight of a salt of the formula FORM:1037017/C3/1 wherein R and R1 are individually alkyl of 2-18 carbon atoms, cycloalkyl of 5-6 carbon atoms, monocyclic aralkyl of 7 to 10 carbon atoms or cyanoethyl; and Me is a cation of a metal consisting of Zn, Ni, Pt, Cd, Ca, Ba, Mg, Cu, Sn or Mn (see Division C2). The compounds of the above formula are incorporated into the polymer to be stabilized by conventional mixing and milling means. The polymer may contain in addition other stabilizers, colouring agents, extenders, plasticizers or solvents. An example is given in which polypropylene is milled with stabilizers of the above general formula and tested for stability, and compared with the properties of the following dithiophosphurates: ammonium dicyclohexyl, ammonium di-n-butyl, zinc diphenyl and dicyclohexyl acid.