Ube Industries, Inc.

Tosio Isida

Yoshihiro Kusuki

Takashi Harada

Hiroshi Makino

Hiroshi Shimazaki

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:

Porous aromatic imide polymer membrane and a process for its manufacture

A modified polymeric membrane having an excellent separating property is produced by applying, to a porous polymeric membrane, a volatile treating liquid containing a modifying agent which consists of at least one member selected from: (A) volatile dissolving organic liquids each capable of dissolving therein at least 1% by weight of the porous polymeric membrane at a temperature of 25.degree. C.; and

Process for modifying porous polymeric membrane

An aromatic polyimide separating membrane is produced by a process comprising the steps of:

Production of aromatic polyimide separating membranes

An aromatic polyimide membrane having an excellent gas-separating property comprises (A) a substrate consisting of a porous membrane comprising at least one aromatic polyimide having at least 80 molar % of at least one type of recurring unit of the formula (I): ##STR1## wherein R is a tetravalent aromatic radical and R.sup.1 is a divalent aromatic radical, the porous membrane exhibiting a hydrogen gas permeability (PH.sub.2) of 1.times.10.sup.-5 to 5.times.10.sup.-1 cm.sup.3 /cm.sup.2.sec.cmHg and a ratio of hydrogen gas permeability (PH.sub.2) to carbon monoxide gas permeability (PCO) of 2 to 5; and (B) 50% or more, based on the weight of the porous membrane substrate, of a gas-separating liquid contained in the porous membrane substrate, the gas-separating liquid being substantially incapable of dissolving therein the porous membrane substrate and having a boiling point of 180.degree. C. or more.

Aromatic polyimide gas-separating membrane

A porous membrane of an aromatic polyimide having an enhanced permeability of a gas or liquid is produced by a process comprising the steps of

Process for producing porous aromatic polyimide membranes

An aromatic polyimide composite membrane having an excellent gas-separating property is produced by a process comprising the steps of: coating at least one surface of a substrate consisting of an aromatic polyimide porous membrane with a solution of 0.05% to 10% by weight of an aromatic polyamic acid in a polar organic solvent, which is not capable of dissolving the polyimide porous membrane, at a temperature not exceeding 140.degree. C.; after a during drying the resultant thin coating layer of the polyamic acid solution, heating the resultant polyamic acid layer at a temperature of 150.degree. C. or more so as to convert the polyamic acid layer to the corresponding polyimide layer.

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Ichihara, Japan

Tosio Isida