The present invention relates to a composite porous hollow-fiber membrane including a first layer and a second layer which each include a fluororesin-based polymer, in which at least a part of molecular chains of the fluororesin-based polymer is oriented in a longitudinal direction of the composite porous hollow-fiber membrane, the molecular chains of the fluororesin-based polymer have a degree of orientation it in the longitudinal direction of the composite porous hollow-fiber membrane of 0.4 or higher but less than 1.0, the degree of orientation it being calculated with the specific formula.

The present invention provides a porous hollow fiber membrane that has both high strength and high pure water permeability, and that exhibits excellent thermal deformation resistance. The present invention is related to a porous hollow fiber membrane containing a fluororesin-based polymer, and a manufacturing method of the membrane comprises a drawing step and a relaxing step. The porous hollow fiber membrane is characterized in that: the molecular chain of the polymer is oriented in the longitudinal direction of the hollow fiber membrane; and at the same time internal distortion of oriented non-crystalline chains, which is disadvantageous in terms of entropy, is alleviated.

Provided is a porous hollow fiber membrane made of a thermoplastic resin, wherein a membrane thickness is 0.050 mm or larger and 0.25 mm or smaller, and when a strength coefficient is defined as K=(compressive strength)/((membrane thickness)/(inside diameter/2)).sup.3, K=1.7 or more.

A polymeric hollow fiber membrane is provided having a crosslinked selective layer formed by sequentially performing coating of a polymer precursor on a crosslinked polymeric hollow fiber membrane support and thermal condensation and thermal crosslinking thereof, a carbon molecular sieve hollow fiber membrane, methods for producing the same, and methods of separating gases using the same. The polymeric hollow fiber membrane and the carbon molecular sieve hollow fiber membrane each have a thin crosslinked selective layer and excellent plasticization resistance and separation performance. Accordingly, the polymeric hollow fiber membrane and the carbon molecular sieve hollow fiber membrane, each of which has a thin crosslinked selective layer, can be effectively used in the separation of a mixed gas.

Disclosed are a method for preparing a high-strength anti-pollution anti-bacterial hollow fiber nano-filtration membrane and a product prepared by the method. The method comprises: S1, a chemical crosslinking reaction: placing an ultra-filtration base membrane in an acidic aqueous solution of glucose or an aqueous solution of phytic acid for a chemical crosslinking reaction to obtain a nano-filtration membrane; S2, a neutralization reaction immersing the nano-filtration membrane obtained in step S1 in an aqueous solution of alkali for the neutralization reaction, then washing the membrane to be neutral; S3, loading inorganic antibacterial agent: placing the membrane obtained in step S2 in an inorganic anti-bacterial agent solution for complexation, thereby obtaining a high-strength anti-pollution anti-bacterial hollow fiber nano-filtration membrane.

Provided is a vinylidene fluoride porous hollow fiber membrane excellent in fouling resistance due to reduced organic substance absorbance, preferably having preferable pore structures to enable to have high permeability, high fractionation performance, and good process controllability. The membrane includes a vinylidene fluoride resin and 0.5 to 10% by weight of a hydrophilic resin, having a ratio Pi/Po of 2.5 to 50 where Pi and Po denote an average pore size on inner surface and an average pore size on outer surface, respectively, and having a pure water permeation rate satisfying the following formula:
(FLUX.sub.d/FLUX.sub.w)10040.0 wherein FLUX.sub.d represents a pure water permeation rate (L/m.sup.2/hr/98 kPa) of the hollow fiber membrane in a dry state, and FLUX.sub.w represents a pure water permeation rate (L/m.sup.2/hr/98 kPa) of the hollow fiber membrane in a wet state.

A filtration membrane made by a method that includes: a) selecting and preparing an organic polymer, such as a collodion; b) injecting a collodion into at least one channel of an extrusion die that also comprises an extrusion die core and at least one outlet; c) injecting an internal liquid into a hollow centering pin, the hollow centering pin comprising a channel positioned on the core of the extrusion die and also positioned at an axis of the outlet of the extrusion die; d) applying a holding film to the outlet of the extrusion die; e) unrolling the holding film onto a surface of at least one hollow fiber emerging from the outlet of the extrusion die; f) immersing the hollow fiber with the first holding film in a rinsing solution so as to obtain a flat hollow fiber filtration membrane; and ending the rinsing of the filtration membrane.

The present invention provides a hollow fiber membrane including a cellulose acetate-based polymer, in which when an inner surface of the hollow fiber membrane is observed under an atomic force microscope, a plurality of groove-like recesses oriented in a lengthwise direction of the hollow fiber membrane are observed, an average length of the recesses is greater than or equal to 200 nm and less than or equal to 500 nm, an average width of the recesses is greater than or equal to 15 nm and less than or equal to 50 nm, and an aspect ratio defined as a ratio of the average length to the average width of each of the recesses is greater than or equal to 6 and less than or equal to 22.

Described herein is a polyamide hollow fiber membrane and methods of making and using the hollow fiber membrane. The polyamide hollow fiber membrane has an isopropanol permeability of from about 5 L/m2 h bar to about 150 L/m2 h bar and a particle rejection percentage of about 100% for particles having a nominal diameter of from about 1 nm to about 25 nm. The polyamide hollow fiber membranes described herein are particularly useful for photoresist filtration, for example.

A method for manufacturing a hollow fiber membrane wherein a spinning stock solution containing 10 mass % or more and 40 mass % or less of a polysulfone-based resin, 1 mass % or more and 30 mass % or less of polyvinylpyrrolidone, and 1 mass % or more and 80 mass % or less of N,N-dimethylformamide is discharged together with a core liquid from a double-ring nozzle to produce a hollow fiber membrane by dry-wet spinning, and then the hollow fiber membrane is subjected to a dry heat treatment at a temperature of 80? C. or higher and 100? C. or lower for 48 hours or longer and 168 hours or shorter.