FLUOROELASTLATEX AV EN VINYLIDENFLUORIDHALTIG SAMPOLYMER SAMT FORFARANDE FOR FRAMSTELLNING AV DENNA LATEX

摘要

1475623 Production of stable fluoroelastomer latex E I DU PONT DE NEMOURS & CO 14 July 1975 [15 July 1974] 29473/75 Heading C3P A stable fluoroelastomer latex is prepared by (A) forming a fluoro elastomer-forming emulsion comprising (1) vinylidone fluoride and at least one other fluorine-containing monomer (the total monomer content of the emulsion being 10-35 wt. per cent) (2) from 30-100 parts by wt. of lithium ions per 100 parts of the emulsion and (3) a free radical initiator; (B) effecting polymerization at 50-135‹ C. and 7-140 kg./ cm.2 pressure and (C) adding a creaming agent to the formed latex in an amount of 0À07-3À0 gms. per 100 gms. of fluoro-elastomer. After step (B) the pH is preferably adjusted to 4.5 to 7, preferably by adding LiOH, and optional further steps after (C) comprise: (D) creaming the latex to form a creamed latex having a fluoroelastomer content of 40-75 wt. per cent, and (E) isolating said creamed latex. The preferred product of the process has the following properties: (a) a fluoroelastomer content 10-75 wt. per cent; (b) a lithium ion content of 30- 400 parts per million; (c) a pH of 3 to 7 and (d) a creaming agent content of 0À07-3À0 gms. per 100 gms of fluoroelastomer. In the examples the fluoroelastomer is a copolymer of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene. The creaming agent used is sodium or ammonium alginate.