Patent ID: 7022280

Claim:
A process for producing a flat yarn, which comprises the steps of: (a) providing a polyoxymethylene copolymer having a melt index at 190° C. with a load of 2160 g of 0.3 to 20 g/10 min., the polyoxymethylene copolymer being comprised mainly of repeating oxymethylene units and containing 0.5 to 10 moles of oxyalkylene units represented by the following formula (1) per 100 moles of the oxymethylene units in the polymer chain: in which R 1 and R 2 represent hydrogen atom, an alkyl group of 1 to 8 carbon atoms, an organic group having an alkyl group of 1 to 8 carbon atoms, a phenyl group or an organic group having a phenyl group, R 1 and R 2 may be identical to or different from each other and m represents an integer of 2 to 6; (b) melting the polyoxymethylene copolymer provided according to step (a) and forming a film therefrom by inflation extrusion or T-die extrusion; (c) slitting the film obtained according to step (b) into a plurality of strips by passing the film through a slitter; (d) monoaxially stretching the strips obtained in step (c) 2 to 15 times at a temperature of between 80° C. and 170° C.; and then (e) heat-setting the monoaxially stretched strips at a temperature between 120° C. and 180° C. to obtain a flat yarn thereof.