# US 11,077,407 B2 · Porous hollow-fiber membrane and production process therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,077,407 B2 - Document ID: US11077407B2 - Status: Granted - Kind: B2 - Application number: 16/305,757 - Filed: 2017-05-30 - Published: 2020-08-06 - Granted: 2021-08-03 - Earliest claimed: 2016-05-31 - Assignees: Toray Industries, Inc. - Applicants: Toray Industries, Inc. - Inventors: Kenta Iwai; Masayuki Hanakawa; Tamotsu Kitade; Masahiro Kimura; Toshiyuki Ishizaki - Web page: https://patentgrep.com/patent/US11077407B2 ## CPC - B01D 69/02: characterised by their properties - B01D 67/0018: {Thermally induced processes [TIPS]} - B01D 67/0027: {by stretching} - B01D 69/08: Hollow fibre membranes (manufacture of hollow fibres D01D5/24, D01F1/08) - B01D 71/34: Polyvinylidene fluoride - C08J 9/26: by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out - D01F 6/12: from polymers of fluorinated hydrocarbons - B01D 2325/02: Details relating to pores or porosity of the membranes - B01D 2325/20: Specific permeability or cut-off range - B01D 2325/24: Mechanical properties, e.g. strength - B01D 2325/30: Chemical resistance - B01D 2325/34: Molecular weight or degree of polymerisation - C02F 1/44: by dialysis, osmosis or reverse osmosis {(general membrane separation processes B01D61/00, membrane modules B01D63/00, electrodialysis C02F1/4693, combination of membrane modules and bioreactors C02F3/1268)} - C02F 2103/08: Seawater, e.g. for desalination - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) ## Abstract The porous hollow-fiber membrane of the present invention comprises a fluororesin polymer, and has columnar structures oriented in the longitudinal direction thereof. In the porous hollow-fiber membrane, molecular chains of the fluororesin polymer have been oriented in the longitudinal direction of the porous hollow-fiber membrane and have an average value ν of Raman orientation parameter of 1.5-4.0. ## Claims ### Claim 1 A porous hollow-fiber membrane comprising a fluororesin-based polymer, wherein the porous hollow-fiber membrane has a columnar texture oriented in a longitudinal direction thereof, a molecular chain in the columnar texture is oriented in the longitudinal direction of the porous hollow-fiber membrane, and the molecular chain has an average value v of a Raman orientation parameter being from 1.5 to 4.0: Raman orientation parameter =(I1270/I840) parallel/(I1270/I840) perpendicular (1), wherein parallel condition: the longitudinal direction of the porous hollow-fiber membrane is parallel to a polarization direction; perpendicular condition: the longitudinal direction of the porous hollow-fiber membrane is orthogonal to the polarization direction; I1270 parallel: the intensity of Raman band at 1,270 cm−1 under the parallel condition; I1270 perpendicular: the intensity of Raman band at 1,270 cm−1 under the perpendicular condition; I840 parallel: the intensity of Raman band at 840 cm−1 under the parallel condition; and I840 perpendicular: the intensity of Raman band at 840 cm−1 under the perpendicular condition. ### Claim 2 (depends on 1) The porous hollow-fiber membrane according to claim 1, wherein the columnar texture has a short-side length of from 0.5 to 3 μm and an aspect ratio of 3 or more. ### Claim 3 (depends on 1) The porous hollow-fiber membrane according to claim 1, wherein a thickness uniformity of the columnar texture is 0.50 or more. ### Claim 4 (depends on 1) The porous hollow-fiber membrane according to claim 1, wherein the molecular chain in the columnar texture has a ratio M/m of a maximum Raman orientation parameter M to a minimum Raman orientation parameter m being from 1.5 to 4.0. ### Claim 5 (depends on 1) The porous hollow-fiber membrane according to claim 1, having a maximum Raman orientation parameter M of the molecular chain in the columnar texture being 4.0 or less. ### Claim 6 (depends on 1) The porous hollow-fiber membrane according to claim 1, having a porosity being from 40 to 80%. ### Claim 7 (depends on 1) The porous hollow-fiber membrane according to claim 1, having a pure-water permeation performance at 50 kPa and 25° C. being 0.7 m3/m2/hr or more, a breaking strength being 23 MPa or more, and a Young's modulus being from 0.15 to 0.40 GPa. ### Claim 8 (depends on 1) The porous hollow-fiber membrane according to claim 1, wherein the molecular chain of the fluororesin-based polymer has an orientation degree π in the longitudinal direction of the porous hollow-fiber membrane, calculated based on the following formula (2), being less than 0.4, or the molecular chain of the fluororesin-based polymer is non-oriented: Orientation degree π=(180°−H)/180° (2), wherein (H is a half-width)(° of a diffraction intensity distribution in a circumferential direction of a wide-angle X-ray diffraction) image. ### Claim 9 (depends on 1) A method for producing a porous hollow-fiber membrane according to claim 1, comprising the following steps 1) and 2): 1) a step of forming a porous hollow fiber having a columnar texture from a membrane-forming solution containing a fluororesin-based polymer by thermally induced phase separation, wherein the columnar texture is oriented in a longitudinal direction and has a thickness uniformity of 0.50 or more and less than 1.00; and 2) a step of stretching the porous hollow fiber obtained in 1) above to 1.8 to 2.4 times in the longitudinal direction at a rate of 1 to 150%/s. ### Claim 10 (depends on 9) The method for producing a porous hollow-fiber membrane according to claim 9, wherein the thermally induced phase separation of the step 1) includes at least one cooling step of the following a) and b): a) a step of soaking the membrane-forming solution in a cooling bath at a temperature Tb satisfying Tc−30° C.