Ube Industries, Inc.

Agency of Industrial Science and Technology

Director-general of Agency of Industrial Science and Technology

Yoshihiro Kusuki

Takashi Harada

Hiroshi Shimazaki

Hiroshi Makino

Tosio Isida

Toshimune Yoshinaga

Shunsuke Nakanishi

Asumaru Nakamura

Masao Kikuchi

Masayuki Nakatani

Kenji Ito

Makoto Matsuo

Hiroshi Yoshida

Hidetomo Ashitaka

Nozomu Tanihara

Denichi Oda

Harutoshi Hoshino

Yoshiyuki Sumiyama

Shinji Asanuma

Mitsuo Maeda

Akira Nagasaka

Tatsuo Yamamoto

Yoshio Takeuchi

Kazuhiko Ishihara

An asymmetric membrane is formed using a mixture of two or more different polymers including at least one type of polyimide. It is thereby possible to produce a gas separation membrane with low permeation resistance (a high permeation rate) for permeate gases passing through the porous layer of the membrane, which also maintains a practical level of mechanical strength of the membrane and has excellent water resistance and hot water resistance.

Gas separation membrane and method for its use

A partially carbonized asymmetric hollow fiber separation membrane which is a hollow fiber separation membrane having an asymmetric structure obtained by partial carbonization of an aromatic polyimide hollow fiber separation membrane with an asymmetric structure, wherein the thickness of the aromatic polyimide hollow fiber membrane to be partially carbonized is 8-50 &mgr;m, the thickness of the hollow fiber separation membrane obtained by the carbonization is 8-45 &mgr;m, and the carbon content of the hollow fiber membrane obtained by partial carbonization is at least 1.05 times the carbon content of the aromatic polyimide hollow fiber membrane to be partially carbonized, and no greater than 90 wt %; also, a process for its production and a gas separation method employing it.

Partially carbonized asymmetric hollow fiber separation membrane, process for its production, and gas separation method

A mixed gas-separating membrane module having a high separating efficiency includes a cylindrical container having a mixed gas-feed section, a non-permeated gas-delivery section, and a middle section; a bundle of a plurality of hollow fibers each extending through the middle section and each having an end portion opening to the mixed gas-feed section and an opposite end portion opening to the non-permeated gas-delivery section; a pair of a first disk supporting the hollow fiber end portion opening to the mixed gas-feed section and partitioning the middle section from the mixed gas-feed section, and a second disk supporting the opposite hollow fiber end portions opening to the non-permeated gas-delivery section and partitioning the middle section from the non-permeated gas-delivery section, the first and second disks supporting the hollow fibers so that the hollow fibers are spaced from each other, to leave a continuous space between the hollow fibers; and a cylindrical film member surrounding the hollow fiber bundle to such an extent that the continuous space formed between the hollow fibers is connected to a permeated gas-delivery outlet of the middle section, the middle section, having a permeated gas-delivery outlet located close to the first disk and a carrier gas-feed inlet located close to or in the second disk, to allow the carrier gas fed into the middle section to flow through the continuous space, countercurrently to the flow of the mixed gas through the hollow fibers.

Mixed gas-separating membrane module and process

An aromatic polyimide having a recurring unit of the formula (I): ##STR1## wherein Ar is a divalent aromatic group having one or two benzene rings which has a sulfonate group of --SO.sub.3 H, --SO.sub.3 M, and --SO.sub.3 N(L).sub.4 on the ring, wherein M is an alkali metal and L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, is favorably employed in the form of a semipermeable film for gas separation.

Aromatic polyimide and gas separation

A gas separating asymmetric membrane such as a gas separating asymmetric hollow fiber comprises an aromatic polyimide comprising recurring units of the formulae (I) and (II): ##STR1## wherein A.sup.1 is a tetravalent unit having a diphenylhexafluoropropane structure, A.sup.2 is a tetravalent unit having a benzene structure, and A.sup.3 is a divalent aromatic unit which is a unit derived from a sulfur atom-containing diamine such as diaminodibenzothiophene, diaminodiphenylenesulfone, diaminothioxanthene-5,5-dioxide or diaminothioxanthone-5,5-dioxide. The aromatic polyimide contains the recurring unit of the formula (I) in an amount of 40 to 90 molar % and the recurring unit of the formula (II) in an amount of 10 to 40 molar %. Further, a process for the preparation of the gas separating asymmetric hollow fiber membrane is also disclosed.

Gas separating asymmetric membrane

A method of enhancing the gas-separation performance of an aromatic polyimide membrane with high reproducibility, by plasma-treating an asymmetric aromatic polyimide membrane comprising 80 to 100 molar % of at least one type of recurring units selected from those of the formulae (A) and (B) and 0 to 20 molar % of recurring units of the formula (C): ##STR1## in the formulae of which, R.sup.1, R.sup.2, R.sup.3 =an aromatic residue derived from an aromatic diamine compound and R=a tetravalent aromatic residue derived from an aromatic tetracarboxylic acid compound and different from tetravalent the aromatic tetracarboxylic acid residues appearing in the formulae (A) and (B), and has a helium gas-permeation rate [P.sub.He ] of 1.times.10.sup.-4 cm.sup.3 /cm.sup.2.sec.cmHg or more at 80.degree. C. and a ratio [P.sub.He ]/[P.sub.N2 ] of the helium gaspermeation rate [P.sub.He ] to a nitrogen gas-permeation rate [P.sub.N2 ] of 20 or more at 80.degree. C., in an atmosphere comprising ammonia.

Method of enhancing gas separation performance of an aromatic polyimide

An aromatic polyimide double layered hollow filamentary membrane having an excellent heat resistance, chemical resistance, pressure-resistance, and gas-permeating and separating properties comprises (A) an aromatic imide polymer hollow filamentary microporous inner layer and (B) an aromatic imide polymer tubular filamentary asymmetric outer layer composed of (a) tubular filamentary microporous intermediate layer covering and united with the outside surface of the inner layer (A) and (b) a thin dense outside surface layer covering and united with the intermediate layer (a).

Aromatic polyimide double layered hollow filamentary membrane and

A purified light gas consisting of hydrogen or helium and having a high purity of, for example, 99.99% or more is prepared from a feed gas containing at least 90 molar % or more of H.sub.2 or He and substantially no CO.sub.2 by gas-separating the feed gas through a plurality of gas-separating membrane modules each comprising at least one polymeric gas-separating membrane and having a gas-permeating ratio P.sub.A /P.sub.CH4 of 100 or more, wherein P.sub.A is a permeating rate of the light gas and P.sub.CH4 is a permeating rate of methane gas, in such a manner that each fraction of the feed gas permeated through and delivered from a preceding membrane module is fed to a next membrane module under the pressure, per se, of the delivered fraction of the feed gas without pressurizing the delivered fraction.

Method of preparing high purity light gas by multiple-step gas separation

A pervaporation separation method of water from an organic material aqueous solution at a high separating efficiency is effected by using a specific asymmetric separating membrane comprising a heat-resistant, solvent-soluble aromatic imide polymer prepared by the polymerization and imidization of an aromatic tetracarboxylic acid component comprising, as a principal ingredient, at least one biphenyl tetracarboxylic acid compound with an aromatic diamine component comprising a principal member selected from: ##STR1## and an additional member selected from another aromatic diamine compounds having 2 to 5 benzene ring structures and different from the diamine compounds (I) and (II).

Pervaporation method of selectively separating water from an organic

A pervaporation method of separating a liquid organic compound mixture at a high speed and efficiency through an aromatic polyimide asymmetric separating membrane produced from an aromatic tetracarboxylic acid component comprising at least 70 molar % of biphenyl or diphenylether tetracarboxylic dianhydride and an aromatic diamine component comprising 85 molar % or more of an aromatic diamine having 2 to 3 benzene ring structure, or 15 molar % or more of 9,10-di(aminophenyl)anthracene, di(aminophenoxy)diphenylsulfone, di(aminophenoxy)biphenyl or di(aminophenoxy)diphenylalkane compounds, or a mixture of 15 to 50 molar % of an aromatic diamine having alone benzene or pyridine ring structure and 50 to 85 molar % of an aromatic diamine having a 2 to 3 benzene ring structure.

Pervaporation method of separating liquid organic compound mixture

An aromatic imide polymer hollow filament having an excellent gas separating property is produced by a process comprising the steps of:

Process for producing aromatic imide polymer hollow filaments

Aromatic imide polymer hollow filaments

A method for piling and cleaning a spun yarn in a wet spinning in which a yarn is withdrawn at a predetermined velocity and is dropped by its own weight into a rotating cylindrical container with the bottom formed with drain holes while simultaneously traversing the yarn in the radial direction of the cylindrical container so that the yarn is piled at the bottom of the cylindrical container in the form of a ring; and a cleaning liquid is sprayed against the yarn which is being piled, thereby cleaning the yarn.

Spun yarn piling and cleaning method

An aromatic polyimide composite membrane having a satisfactory gas-permeating property and an excellent gas-separating property comprises an aromatic polyimide porous membrane substrate and at least one coating layer which has been prepared (A) by coating at least one surface of the substrate with a dilute dope solution containing 0.01 to 5 parts by weight of a soluble aromatic polyimide and/or polyamic acid dissolved in a solvent which consists essentially of 100 parts by weight of a base component incapable of dissolving therein the substrate in an amount of 3% by weight or more and 0 to 15 parts by weight of an additional component capable of dissolving therein the 5% by weight or more of the aromatic polymeric material and compatible with the base component; and (B) by gradually evaporating the solvent from the coated dilute dope solution layer.

Aromatic polyimide composite separating membrane

A porous aromatic imide polymer membrane usable as a gas or liquid separator or concentrator is prepared by a process comprising the steps of:

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Ichihara, Japan

Yoshihiro Kusuki