Patent GB-595999-A (GB)
Title: Improvements in production of spinnable vinyl resin compositions
IPC: C08L27/06
Filed: 1945-07-13
Abstract: The spinning characteristics of difficultly spinnable dispersions of vinyl resins in a solvent are improved by heating the dispersions at a temperature between 80 DEG  and 100 DEG  C. for between 5 minutes and 1 hour while under superatmospheric pressure to minimize evaporation of the solvent and then conducting the heated dispersion to a spinning zone while at a temperature of between 30 DEG  and 55 DEG  C.  The resins may be copolymers of a vinyl halide and a vinyl ester of an aliphatic acid or of a vinyl halide and acrylonitrile prepared by emulsion polymerization.  Such resins should contain vinyl chloride contents of 90-92 per cent in the first case and 45-80 per cent in the second.  The solvent may be acetone, and it may be diluted with an organic diluent. The dispersion may be heated in an inert atmosphere such as nitrogen or carbon dioxide and it should be agitated during the heating.  The heating may be carried out before, during or after filtration of the dispersion, and it may be batchwise or continuous.  After heating, the dispersion, still under pressure, is allowed to cool to between 30 DEG  and 55 DEG  C. and to de-aerate before being pumped to the spinning apparatus.  Any known method of "wet-" or "dry-spinning" may be employed.  Small amounts of heat stabilizers such as lead and tin organo-metallic compounds or the organo-metallic tin salts of alpha-beta-olefinic carboxylic acids may be added to the dispersion prior to the heat treatment. After spinning, the filaments may be stretched from 400 per cent to 1300 per cent by a known stretching treatment such as heating in a steam cell at temperatures above 100 DEG  C.  If the heat treatment is given before filtration, it may be carried out in the same kneader in which the dispersion is prepared.  In an example, a resin formed by the copolymerization of vinyl chloride and vinyl acetate containing 91.1 per cent of vinyl chloride and an average molecular weight of 26,800 was kneaded in a mixer with acetone at temperatures between 40 DEG  and 55 DEG  C.  The viscous dispersion so obtained contained 31 per cent of the resin. It was then heated at 90 DEG  C. for 1 hour in a glass-lined autoclave having an agitator and in an atmosphere of nitrogen maintained under a pressure of 45 lbs. per sq. inch.  After dilution to a resin content of 27 per cent, it was filtered through a pressure filter at 85 DEG  C. and cooled to 50 DEG  C., and spun at this temperature.  The fibres were stretched 463 per cent in a steam cell at 125 DEG  C.  In another example, a quantity of a vinyl chlorideacrylonitrile copolymer containing 60 per cent of the chloride in the polymer is kneaded with acetone to yield a dispersion containing 19.5 per cent of the resin.  It is filtered under pressure through two jacketed candle-filters arranged in series; the first heated to 85 DEG  C. by hot water in the jacket and the second maintained at room temperature by water at ordinary temperature in the jacket.  The resin is filtered at such a rate that it is exposed to the temperature of 85 DEG  C. for five minutes in the first filter and cooled in the second.  It is transferred to a spinning chamber and dry-spun in the usual way.  The resultant yarn was stretched 1290 per cent at 132 DEG  C. and stabilized without tension for 1 hour in water at 100 DEG  C.