COMPOSITE SUBSTRATE SHEET AND METHOD FOR PRODUCING COMPOSITE SUBSTRATE SHEET

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a composite substrate sheet in which formation of voids can be suppressed when producing a composite substrate by using a coagulation method in a humidity and heat regulated atmosphere via gelatinizing treatment of an aqueous emulsion.SOLUTION: A method for producing a composite substrate includes: (a) a step for forming a fiber web of sea-island type fibers in which a sea component is PVA and an island component is a heat shrinkable polymer; (b) a step for providing a nonwoven fabric by interlacing the fiber web; (c) a step for providing a densified nonwoven fabric by subjecting the nonwoven fabric to wet heat shrinkage treatment; (d) a step for impregnating the densified nonwoven fabric with an aqueous emulsion of a polymer elastomer; (e) a step for gelatinizing the aqueous emulsion impregnated in the densified nonwoven fabric by heating it in a humidity and temperature regulated atmosphere controlled to a predetermined condition and then coagulating it; and (f) a step for removing the sea component from the sea-island type fibers forming the inside of the densified nonwoven fabric by a hot water extraction after the step (e).