Abstract: A laminate integrated by firmly jointing a heat-seal layer in web form made from a mixture of synthetic pulp having a branched configuration and synthetic short fiber to a substrate layer made from natural fiber. The synthetic pulp is made from a resin composition comprised of ethylene-&agr;,&bgr;-unsaturated carboxylic acid copolymer and polyethylene. This laminate has a high degree of air permeability and exhibits a high heat-seal strength and good hot tack even at a temperature of 130° C. On account of said properties it is adequately used as heat-seal paper suited for filter use, in particular raw material paper for tea bags.

Abstract: A polyolefin synthetic pulp comprising a polyolefin resin graft-modified with an unsaturated carboxylic acid or a derivative thereof, and/or a polyolefin resin composition which comprises an ethylene/&agr;,&bgr;-unsaturated carboxylic acid copolymer and a polyethylene resin. Further, there is provided a heat sealing paper comprising a base fiber layer whose at least one surface is laminated and integrated with a layer of the polyolefin synthetic pulp. This polyolefin synthetic pulp has a large breaking length and an excellent internal bond strength, and exhibits stable heat sealing and hot tack properties over a wide temperature range from low to high temperature. The polyolefin synthetic pulp is suitable to use in battery separators, molding fiberboards, heat sealing papers and the like.

Abstract: A bulky synthetic pulp sheet which does not lose its shape even after having absorbed a liquid and has excellent resistance against to chemicals such as acids and alkalis, and a process for preparing the same, which pulp sheet contains 5 to 95% by weight of a synthetic pulp having a drainage factor over a range of from 0.1 to 2.0 sec/g, and 5 to 50% by weight of a polymer binder having a melting point lower than a melting point or a decomposition temperature of said synthetic pulp, the sheet being obtained by subjecting a mixture of the synthetic pulp and fibrous binder to wet laid sheet-making followed by a heat treatment, and having an apparent density of 0.15 g/cm.sup.3 or smaller under the load of 200 g/cm.sup.2.