Asahi Kasei Kogyo Kabushiki Kaisha

Tadahiro Kobayashi

Akio Inoue

Toshio Iwasa

Eiichi Wakita

Hideo Fukuda

Yukio Matsubayashi

Provided is dried porous membrane composed of acrylonitrile polymer walls separating predominantly interconnecting small-size pores. The membrane has surface layers integrated with a support layer to form a single continuous acrylonitrile polymer phase. At least one of the surface layers has pores of from 0.001 to 0.05 micron in average size, and the support layer has pores which are on the average larger than the pores in the surface layer or layers. The membrane has a porosity of from 20% to 70% by volume and a fragility of below 30. The membrane exhibits improved mechanical properties.

Dried porous acrylonitrile polymer membrane, process for producing same

A bulky non-woven fabric of improved softness and uniformity in surface density, flatness and thickness is provided. The non-woven fabric comprises (a) 50 to 95% by weight of spontaneously crimped acrylonitrile polymer fibers having lengths of 4mm to 20mm and at least 20 crimps per inch of length, said acrylonitrile polymer consisting essentially of, in polymerized form, 80 to 100% by weight of acrylonitrile and 0 to 20% by weight of a copolymerizable monoethylenically unsaturated monomer, and (b) 5 to 50% by weight of fibrillated fibers of at least one acrylonitrile polymer, said acrylonitrile polymer comprising, in polymerized form, 60 to 98% by weight of acrylonitrile and 2 to 40% by weight of a copolymerizable monoethylenically unsaturated monomer having a carboxyl group or an amide or N-alkyl substituted amide group. The non-woven fabric is in the form of a web having a structure such that said spontaneously crimped fibers are entangled with both each other and with said fibrillated fibers, and having an apparent density of 0.05 to 0.25 g/cm.sup.3.

Growing community of inventors

Fuji, Japan

Tadahiro Kobayashi