Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/28—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/32—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds comprising halogenated hydrocarbons as the major constituent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
  • B01D67/0002—Organic membrane manufacture
  • B01D67/0023—Organic membrane manufacture by inducing porosity into non porous precursor membranes
  • B01D67/003—Organic membrane manufacture by inducing porosity into non porous precursor membranes by selective elimination of components, e.g. by leaching
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/08—Hollow fibre membranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
  • B01D71/06—Organic material
  • B01D71/30—Polyalkenyl halides
  • B01D71/32—Polyalkenyl halides containing fluorine atoms
  • B01D71/36—Polytetrafluoroethylene
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/24—Formation of filaments, threads, or the like with a hollow structure; Spinnerette packs therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2323/00—Details relating to membrane preparation
  • B01D2323/219—Specific solvent system
  • B01D2323/22—Specific non-solvents or non-solvent system
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/02—Details relating to pores or porosity of the membranes
  • B01D2325/022—Asymmetric membranes
  • B01D2325/0231—Dense layers being placed on the outer side of the cross-section
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/02—Details relating to pores or porosity of the membranes
  • B01D2325/027—Nonporous membranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/30—Chemical resistance
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/34—Molecular weight or degree of polymerisation

Definitions

• Hollow fiber membranes are also used as membrane contactors, typically for degassing or gas absorption applications. Contactors bring together two phases, i.e., two liquid phases, or a liquid and a gas phase for the purpose of transferring a component from one phase to the other.
• a common process is gas-liquid mass transfer, such as gas absorption, in which a gas or a component of a gas stream is absorbed in a liquid.
• Liquid degassing is another example, in which a liquid containing dissolved gas is contacted with an atmosphere, a vacuum or a separate phase to remove the dissolved gas.
• the lumen liquid was replaced with a fluid, preferably a gas, that does not prevent solvent evaporation.
• a fluid preferably a gas
• the superheated solvent evaporates inside the lumen as soon as it emerges from the die.
• the loss of solvent causes a superficial increase in solids concentration on the lumen surface.
• a very thin skin is formed on the lumen surface, while the rest of the membrane forms a microporous structure due to its being submerged in a quenching bath which prevents the porogen from flashing off the outer surface and prevents the formation of a skin on the outer surface.
• porous membranes more specifically, ultrafiltration and contactor membranes, from perfluorinated thermoplastic polymers, more specifically poly(tetrafluoroethylene-co-perfluoro(alkylvinylether)) (poly(PTFE- CO-PFVAE)) or poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), and blends thereof, which are dissolved in a solvent to give a solution having an upper critical solution temperature, and which when the solution is coole ) separates into two phases by liquid-liquid phase separation.
• perfluorinated thermoplastic polymers more specifically poly(tetrafluoroethylene-co-perfluoro(alkylvinylether)) (poly(PTFE- CO-PFVAE)) or poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), and blends thereof, which are dissolved in a solvent to give a solution having an upper critical solution temperature, and which when the solution is cool
• saturated low molecular weight polymers of chlorotrifluoroethylene have been found to be useful solvents.
• a preferred solvent is HaloVac® 60, Halocarbon Products Corporation, River Edge, NJ.
• Figure 1 illustrates the die nose used for vertical fiber spinning.
• the solution is introduced to circular inlet 3 from the cross-head die and is transported to die exit 9.
• Lumen fluid is introduced to the die nose at inlet 2 , and exits at the die exit.
• Heater 5 maintains the solution in a fluid form.
• Temperature sensor 6 is used with a temperature controller to maintain heater 5 at a determined temperature above the separation temperature of the solution.
• Die tip 9 is submerged in cooling bath 7.
• Gel membrane hollow fiber 8 exits the die nose through die exit 9, with the lumen gas filling the inner diameter of the fiber.
• Figure 2 illustrate the die nose used for horizontal fiber spinning.
• the solution is introduced to circular inlet 13 from the cross-head die and is transported to die exit 21.
• the die For horizontal fiber spinning, the die is firmly positioned against an insulated surface as shown in Figure 2.
• the die tip penetrates through a opening having a liquid-tight seal in the insulator.
• a trough for cooling liquid flow is placed in a recess in the opposite side of the insulating seal, in a manner that will maintain the die nose outlet in a submerged condition.
• the trough may be permanently fixed or retractable.
• the trough comprises a longer length of a depth, and a shorter length of less depth, which butts against the insulator in the recess.
• the trough can be of a single depth with for example, pumping means to remove overflow cooling fluid.
• the cooling bath lowers the temperature of the extruded fiber to below the upper critical solution temperature to cause phase separation.
• the bath liquid can be any liquid having a boiling point high enough to prevent bubbles from forming on the fiber exiting the die, and not adversely affecting the surface pore forming process.
• the bath temperature can be from 25°C to 230°C, with a preferred range being 50°C to 150°C.
• Figure 3 illustrates a typical process for vertical spinning to produce the hollow fibers of the invention.
• the polymer/solvent paste-like mixture is introduced into a heated barrel extruder 31 through inlet 32, by means of a pumping system 47, for example, a progressive cavity pump.
• a solution is formed is formed in the heated barrel of extruder 31.
• Extruder 31 conveys the heated solution through conduit 33 into melt pump 34 which meters the solution, and then through conduit 35 to cross head die 36.
• the solution is conveyed from extruder 31 through conduit 33 into melt pump 34, and then through conduit 48 to solution filter 49, and then through conduit 35 to cross head die 36.
• Figures 4 illustrates a typical process for horizontal spinning to produce the hollow fibers of the invention.
• the polymer/solvent paste-like mixture is introduced into a heated barrel extruder 31 through inlet 32, by means of a pumping system 47, for example, a progressive cavity pump.
• a solution is formed is formed in the heated barrel of extruder 31.
• Extruder 31 conveys the heated solution through conduit 33 into melt pump 34 which meters the solution, and then through conduit 35 to cross head die 36.
• the solution is conveyed from extruder 31 through conduit 33 into melt pump 34, and then through conduit 48 to solution filter 49, and then through conduit 35 to cross head die 36.
• Solvent is then removed from the gel fiber by extraction with a solvent that will not significantly weaken or deleteriously affect the hollow fiber membrane.
• the fiber is then dried under restraint to minimize shrinkage.
• N number of fibers
• the tubing with the fiber loop is mounted into a test holder and connected to a container holding the test fluid and attached to a pressure generating system, such as a pressurized gas tank.
• a pressure generating system such as a pressurized gas tank.
• the pressure in the container is raised at increments, for example, 10 psi steps, and the test fluid forced into the lumens of the fibers. Any intrusion of the test fluid is readily observed as a darkening of the fibers from the test fluid filling the pores of the fibers.
• the pressure of each step is maintained for about 20 minutes, or unless intrusion is observed. If no intrusion is observed, pressure is raised to the next increment and the test continued.
• Hyflon MFA® grade 620 (poly(PTFE-CO-PFVAE)) powder obtained from Ausimont USA, Inc., Thorofare, NJ., was used as received. The powder was mixed with HaloVac® 60 solvent from Halocarbon Oil Inc, River Edge, NJ to produce a paste of 30% by weight polymer solids.
• the polymer/solvent paste mixture is introduced into a heated barrel of a twin screw Baker-Perkins (Saginaw, Ml) extruder having 29mm screws, by means of a Moyno (Springfield, OH)progressive cavity pump.
• the extruder barrel temperatures were set at between 180°C and 300°C.
• Figures 5 and 6 show the inner and outer surface of this hollow fiber membrane.
• the inner surface has a skin while the outer surface shows a porous surface.
• Example 2
• Hyflon MFA ® 620 Poly(PTFE-CO-PFVAE) obtained from Ausimont USA, Inc., Thorofare, NJ., were ground to about 300 micron size and were mixed with HaloVac® 60 from Halocarbon Oil Inc, River edge, NJ to produce a paste of 40% by weight polymer solids.
• Cin is the oxygen cone, in input liquid [ppm]
• C* is the equilibrium oxygen cone, at the gas pressure on the shell side [ppm]
• D is the ID of the fiber [cm]
• D ab is the diffusivity of oxygen in water[cm 2 /s].
• Sherwood and Graetz numbers are dimensionless groups used to describe heat and mass transfer operations.
• the Sherwood number is a dimensionless mass transfer coefficient
• the Graetz number is a dimensionless group that is related to the inverse of the boundary layer thickness.
• a permeation rate of 0.65 ml/min at 50 psi was measured.
• the container and all lines were emptied and N-methyl pyrrolidone (Aldrich Chemical Co. # 24,279-9) was placed in the container.
• the container was pressurized to 60 psi to flush out the methanol from the fibers.
• a permeation rate of 0.25 ml/min at 60 psi was measured.
• the solvent was replaced with a 0.5% solution of polyvinylpyrrolidone in N-methyl pyrrolidone.
• the module was operated in tangential flow mode with the solution passing from the inlet through the lumens and out the now open outlet port. Three permeate samples were taken, the first after a 30 minutes.
• a length of the fiber sample was wrapped in multiple loops around an open rectangular metal frame and clamped at both ends.
• the frame was placed in a degreaser (Baron Blakeslee MLR-LE) containing 1 ,1 dichloro-1-fluoroethane (Florocarbon 141 b, ICI) for approximately 16 hrs.
• the framed sample was allowed to dry at room temperature and it was then heat-set in an oven at 275° C for approximately 10 mins.
• the final fiber is white in appearance and the scanning electron micrographs of its structure are given in Figs. 9-11.
• Fig. 10 shows the morphology of the inside (lumen) surface of the fiber and reveals a highly porous structure.
• Fig.9 shows the morphology of the outside surface of the fiber and reveals a much denser structure.
• Figs. 11 shows the morphology of the cross-section of the fiber near the outside surfaces and shows that the tight layer on the fiber's outside surface is extremely thin in thickness.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Textile Engineering (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Artificial Filaments (AREA)
• Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)

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• 2000
  • 2000-01-27 WO PCT/US2000/002194 patent/WO2000044482A2/en not_active Ceased
  • 2000-01-27 AU AU34753/00A patent/AU3475300A/en not_active Abandoned
  • 2000-01-27 DE DE60029308T patent/DE60029308T2/de not_active Expired - Lifetime
  • 2000-01-27 ES ES00913282T patent/ES2267508T3/es not_active Expired - Lifetime
  • 2000-01-27 JP JP2000595773A patent/JP2002535131A/ja active Pending
  • 2000-01-27 EP EP00913282A patent/EP1154842B1/en not_active Expired - Lifetime
  • 2000-01-27 KR KR1020017009516A patent/KR100901050B1/ko not_active Expired - Fee Related
• 2011
  • 2011-04-21 JP JP2011095303A patent/JP2011200861A/ja active Pending
• 2014
  • 2014-10-08 JP JP2014207363A patent/JP2015061727A/ja active Pending

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