Heat-bondable composite fiber, process for producing the same, and fibrous mass

A method for producing a thermoadhesive conjugate fiber which comprises:

• providing two kinds of polyoxymethylene-based polymers A and B which satisfy:
• 30<MIA wherein MIA is a before-spinning melt index (g/10 min) of the polyoxymethylene-based polymer A, which is determined according to JIS K 7210 (conditions:
• 190° C., load:
• 21.18N (2.16 kg)),
• a before-spinning 150° C. ½ crystallization time of the polyoxymethylene-based polymer B is not less than 10 seconds and less than 30 seconds, and
• TB>TA+10 wherein TA and TB are before-spinning fusion peak temperatures of the polyoxymethylene-based polymers A and B respectively, which are determined according to JIS K 7121,
• compositely spinning a first component comprising the polyoxymethylene-based polymer A and a second component comprising the polyoxymethylene-based polymer B such that the first component is exposed with an exposed length of not less than 20% relative to a peripheral length of the fiber,
• subjecting the spun fiber to a drawing treatment, and
• subjecting the drawn fiber to an annealing treatment at a temperature of from 60° C. to 110° C.

A method for producing a thermoadhesive conjugate fiber, which comprises:

• providing two kinds of polyoxymethylene-based polymers A and B, the polymer B having a before-spinning 150° C. ½ crystallization time of not less than 10 seconds and less than 30 seconds, and the polymers satisfying TB>TA+10 wherein TA and TB are before-spinning fusion peak temperatures of the polyoxymethylene-based polymers A and B respectively which temperatures are determined according to JIS K 7121,
• compositely spinning a first component comprising the polyoxymethylene-based polymer
• A and a second component comprising the polyoxymethylene-based polymer B such that the first component is exposed with an exposed length of not less than 20% relative to a peripheral length of the fiber,
• subjecting the spun fiber to a drawing treatment, and
• subjecting the drawn fiber to an annealing treatment at a temperature of from 60° C. to 110° C.