GB920808A - Method for producing fibers and filaments - Google Patents

Abstract

A method of producing filamentary material comprises spinning a vinyl chloride-fluoroethylene copolymer and drawing the spun filament at above 50 DEG C., the copolymer having been formed at a temperature in the range -150 DEG to 20 DEG C., comprising at least 80 wt. per cent vinyl chloride units and at least 0,50 wt. per cent fluoroethylene units, and having an intrinsic viscosity in cyclohexanone at 30 DEG C. of 0,10 to 0,53. The Copolymers. Are derived from fluoroethylenes of the formula CX1X2=CX3F where X1, X2 and X3 are hydrogen or halogen atoms, e.g. vinyl and vinylidene fluorides, tri- and tetrafluoroethylenes, trifluorochloroethylene and 1:1-difluoro2:2-dichloroethylene. They may also contain a third monomer, e.g. vinyl acetate, vinyl pyridines and vinyl imidazoles. Polymerization may be effected in bulk or in solution, suspension or emulsion, e.g. in alcohols or water, which may contain calcium chloride as freezing depressant. Polymerization catalysts specified are organic and inorganic peroxides, e.g. trichloroacetyl, trifluorodichloropropionyl and hydrogen peroxides, diisopropyl peroxy dicarbonate, and persulphates; organo-metallic and associated compounds such as the trialkyl borons, alone or with peroxides; redox systems of peroxides and reducing agents, e.g. sodium bisulphite, sodium thiosulphate or triethylamine optionally with an accelerator, e.g. ferrous sulphate or silver nitrate; and azo compounds. The degree of polymerization may be regulated with a chain transfer agent, e.g. chloroform or carbon tetrachloride, or modifier, e.g. dodecylmercaptan. In examples copolymers are prepared (1) from vinyl chloride and trifluorochloroethylene in water with a diisopropyl peroxy dicarbonate/sodium bisulphite/ferrous sulphate redox system; (2) as (1) except that the comonomer is tetrafluoroethylene and the peroxy compound is potassium persulphate; (13) from vinyl chloride and tetrafluoroethylene in 10% aqueous methanol using tri-n-butyl boron plus hydrogen peroxide as catalyst; and (14) from vinyl chloride and trifluorochloroethylene in bulk using trichloroacetyl peroxide as catalyst. Copolymer compositions for spinning. The copolymer may be dissolved in isophorone, morphorine, cyclohexanone, dimethylformamide, dimethylacetamide, nitrobenzene, cyclohexylamine, acetophenone or acetonylacetone, all but the first two of which may be used as mixtures with one another or not over 70 vol. per cent of methyl ethyl or isobutyl ketone, mesityl oxide, furfural, tetrahydrofurane, tetrahydrofurfuryl alcohol or dimethyl sulphoxide. Other ingredients mentioned are extrusion aids, e.g. dibutyl or dioctyl phthalate or tributyl phosphate; stabilizers, e.g. lead sulphate, chloride, carbonate, stearate or phthalate, zinc oxide, chloride or phosphate, stannous stearate, organotin mercaptides, cadmium p stearate or laurate, sodium or potassium phosphate, benzyl or methyl epoxystearate, dicyandiamide or o-sulphobenzimide; pigments; titanium dioxide; polymers which improve dye-affinity, e.g. those of basic nitrogen compounds such as vinyl pyridines, vinyl imidazoles and N-alkacrylamides; and polymers which improve moisture absorption, e.g. acetalized polyvinyl alcohol or vinyl acetate-isopropenyl acetate copolymer and its hydrolysis products. Spinning Processes. Melt, semi-melt, wet or dry spinning techniques may be used. In wet spinning the coagulation bath may comprise the solvent and about 7% water at a temperature below 70 DEG C., preferably below 50 DEG C. In dry spinning the gaseous coagulative medium may be disposed in three zones at 100 DEG to 170 DEG C., 180 DEG to 400 DEG C. and 150 DEG to 40 DEG C. respectively from entrance to exit. After formation of the filament it may be subjected to a drawing treatment wherein it is drawn to at least twice the original length but less than its maximum draw ratio. The drawing may be effected in two stages, the first at 50 DEG to 110 DEG C. for 25-60% of the total draw ratio with the remainder at 110 DEG to 190 DEG C. The draw treatment may be followed by a relaxation treatment allowing 5 to 50% shrinkage followed by a heat treatment at 120 DEG to 150 DEG C.