WATER PERMEABLE SHEET FOR CONCRETE FORM AND PRODUCTION THEREOF

摘要

PROBLEM TO BE SOLVED: To facilitate the detachment from molded concrete, to improve workability and to enable repeated use by forming a water permeable sheet from a partially thermally fused long fiber nonwoven fabric and setting the average fiber density thereof to 0.05-0.5g/cm<3> and the average pore size thereof to 5-25μm. SOLUTION: Heating pressure treatment is applied to a long fiber web made of polypropylene by using an embossing roll to form a long fiber nonwoven fabric wherein 30-60% of the surface of the nonwoven fabric is occupied by thermally fused parts with an area of 0.5-2mm<2> formed into a film like state. Further, heating pressure treatment is applied to the long fiber nonwoven fabric at temp. lower than the m.p. of the fibers constituting the nonwoven fabric by using a smooth roll to set the average fiber density of the nonwoven fabric to 0.05-0.5g/cm<3> and the average pare size thereof to 5-25μm.