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OwnerBoris Afanasievich Egorov, Alexandr Sergeevich Grzhimalovsky +3inventors
InventorsBoris Afanasievich Egorov, Alexandr Sergeevich Grzhimalovsky, Alexandr Vladimirovich Judin, Konstantin Evgenievich Fishman, Ljudmila Dmitrievna Vernaya
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A method of manufacturing polymethylene filaments, wherein polyoxymethylene having the molecular weight from 30,000 to 100,000 and containing stabilizing additives in a quantity from 0.1 to 3.0 per cent of the weight of the polyoxymethylene is subjected to thermal treatment at a temperature from 100.degree. to 150.degree. C. and residual pressure from 1 to 100 mm mercury to attain constant weight. The thus thermally treated polyoxymethylene is melted at a temperature from 170.degree. to 230.degree. C., whereafter the melt is forced through the orifices of an extrusion nozzle. The jets of the melt, leaving the orifices of the extrusion nozzle, are cooled at a temperature from 70.degree. to 169.degree. C. After the cooling the obtained filaments are drawn at a temperature from 120.degree. to 165.degree. C. to a length exceeding from 7 to 14 times the initial length. The disclosed method offers a simple technology of producing filaments as strong as 100 grams per tex. To produce low-shrinkage fiber (i.e. with a shrinkage rate from 0 to 5 per cent at 150.degree. C.) the drawn filaments are thermally treated at a temperature exceeding that of the drawing by 2.degree. C. to 50.degree. C., the filaments being maintained under tension. Alternatively, the drawn filaments may be first tensioned and then thermally treated, as indicated hereinabove.
A method of manufacturing a polyoxymethylene filament, comprising thermally treating polyoxymethylene having a molecular weight of from 30,000 to 100,000 and containing stabilizing additives including an antioxidant and an acceptor of formaldehyde in a quantity from 0.1 to 3.0% of the weight of said polyoxymethylene at a temperature of from 100.degree. to 150.degree. C and a residual pressure of from 1 to 100 mm. Hg to constant weight, melting said thermally treated polyoxymethylene at a temperature of from 170.degree. to 230.degree. C, forcing the melt through the orifices of an extrusion nozzle, cooling the jets of said melt leaving the orifices of the extrusion nozzle to a temperature of from 70.degree. to 169.degree. C in a cooling medium selected from the group consisting of air, an inert gas and steam, and drawing the moulded filament obtained after said cooling at a temperature of from 120.degree. to 165.degree. C to a length exceeding the initial length by about 7 to 14 times to obtain a polyoxymethylene filament having a tensile strength of from 70 to 100 grams per tex, an elongation at rupture of from 9% to 12%, and an initial modulus of from 1200 to 1800 kilograms per square millimeter.
A method of manufacturing a polyoxymethylene filament comprising thermally treating polyoxymethylene having a molecular weight of from 30,000 to 100,000 and containing stabilizing additives comprising an antioxidant and an acceptor of formaldehyde in a quantity of from 0.1 to 3.0% of the weight of said polyoxymethylene at a temperature of from 100.degree. to 150.degree. C and at a residual pressure of from 1 to 100 mm. Hg to constant weight, melting said thermally treated polyoxymethylene at a temperature of from 170.degree. to 230.degree. C, forcing the melt through the orifices of an extrusion nozzle, cooling the jets of said melt leaving the orifices of the extrusion nozzle to a temperature of from 70.degree. to 169.degree. C in a cooling medium selected from the group consisting of air, an inert gas and steam, drawing the moulded filament obtained after said cooling at a temperature of from 120.degree. to 165.degree. C to a length exceeding the initial length by about from 7 to 14 times to obtain a polyoxymethylene filament having a tensile strength of from 70 to 100 grams per tex, an elongation at rupture of about from 9% to 12%, and an initial modulus of about from 1200 to 1800 kilograms per square millimeter, and thermally treating the drawn filament, while maintaining it under tension, at a temperature of from 2.degree. to 50.degree. C above the temperature at which the filament was drawn to produce a polyoxymethylene filament having a shrinkage rate of from 0 to 5% at 150.degree. C.
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