POLYPHENYLENE SULFIDE FIBER, PROCESS FOR PRODUCING THE SAME, WET-LAID NONWOVEN FABRIC, AND PROCESS FOR PRODUCING WET-LAID NONWOVEN FABRIC

摘要

Provided are a polyphenylene sulfide fiber which is amorphous, low in degree of thermal shrinkage, and suitable as a binder for papermaking, and a method for producing the same, as well as a wet-laid nonwoven fabric containing the polyphenylene sulfide fiber and a method for producing a highly insulating wet-laid nonwoven fabric. A polyphenylene sulfide fiber wherein the amount of heat of crystallization measured by DSC is 10 J/g or more and the degree of shrinkage on dry heating of 150°C×30 minutes is 20% or less, and a method for producing a densified wet-laid nonwoven fabric wherein a wet-laid nonwoven fabric that contains 60 to 100% by mass of a polyphenylene sulfide fiber having an amount of heat of crystallization of 10 J/g or more wherein the amount of heat of crystallization of the polyphenylene sulfide fiber before heating-pressurizing treatments is 5 J/g or more is subjected to heating-pressurizing treatment at a temperature that is not lower than the glass transition temperature and not higher than the melting point of the polyphenylene sulfide fiber.