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US4581140A
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Porous regenerated cellulose membrane and process for the preparation thereof
Assignee: Asahi Kasei Corp
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Filing: 1982-11-19
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Granted: 1986-04-08
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Expires: 2002-11-19
Abstract
Abstract A porous regenerated cellulose membrane consisting essentially of cellulose molecules having a viscosity average molecular weight of at least about 5×10 4 , the crystalline region of the cellulose molecules being substantially cellulose II crystal, cellulose III-2 crystal or the mixture thereof and having a degree of crystal orientation at a face of (101) in the crystalline region in the direction of the surface of the membrane of at most about 40%, the membrane having a dynamic modulus at 30° C. measured with a frequency of 110 Hz of at least about 1.5×10 8 (100-prρ) dyn/cm 2 wherein Prρ is a porosity by percentage, a mean pore size represented by D(μm) of about 0.01 μm to about 20 μm and at the same time a porosity in a plane of at least one plane of at least about 30% or a number of pores in a plane per 1 cm 2 of about 6×10 5 /D to about 3×10 7 /D; and a process for preparing the same.
Inventors
- 👤 Seiichi Manabe
- 👤 Michitaka Iwata
- 👤 Mamoru Inoue
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:27
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/08; B01D71/10; C; C08; C08L; C08L1/00; C08L1/02; C08L1/06
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
153 words
A porous regenerated cellulose membrane consisting essentially of cellulose molecules having a viscosity average molecular weight of at least 5×10 4 , the crystalline region of the cellulose molecules being substantially cellulose II crystal, cellulose III-2 crystal or the mixture thereof and having a degree of crystal orientation at a face of (101) in the crystalline region in the direction of the surface of the membrane of at most 40%, the membrane having a dynamic modulus at 30° C. measured with a frequency of 110 Hz of at least 1.5×10 8 (100-Prρ) dyn/cm 2 wherein Prρ is a porosity by percentage, a mean pore size represented by D(μm) of 0.01 μm to 20 μm and at the same time a porosity in a plane of at least one plane of at least 30% or a number of pores in a plane per 1 cm 2 of 6×10 5 /D to 3×10 7 /D.
Claim 2
Dependent Claim
153 words
A porous regenerated cellulose membrane consisting essentially of cellulose molecules having a viscosity average molecular weight of at least 5×10 4 , the crystalline region of the cellulose molecules being substantially cellulose II crystal, cellulose III-2 crystal or the mixture thereof and having a degree of crystal orientation at a face of (101) in the crystalline region in the direction of the surface of the membrane of at most 40%, the membrane having a dynamic modulus at 30° C. measured with a frequency of 110 Hz of at least 1.5×10 8 (100-Prρ) dyn/cm 2 wherein Prρ is a porosity by percentage, a mean pore size represented by D(μm) of 0.01 μm to 20 μm and at the same time a porosity in a plane of at least one plane of at least 30% or a number of pores in a plane per 1 cm 2 of 6×10 5 /D to 3×10 7 /D.
Claim 3
Dependent Claim
22 words
Porous regenerated cellulose membrane of claim 1, wherein the porosity in a plane of at least one plane is 55% to 90%.
Claim 4
Dependent Claim
38 words
Porous regenerated cellulose membrane of claim 1 having a peak temperature [T max (° C.)] at the peak of a dynamic mechanical loss tangent (tan δ) measured with a frequency of 110 Hz of at least 250° C.
Claim 5
Dependent Claim
36 words
Porous regenerated cellulose membrane of claim 1 having a T max (° C.) of 200° C. to 250° C. and a peak value of the dynamic mechanical loss tangent [(tan δ) max] of at least 0.15.
Claim 6
Dependent Claim
43 words
Porous regenerated cellulose membrane of claim 1 wherein at least 50% by volume fraction of the polymers constituting the membrane is in the form of particles having a size of 0.01 μm to 1 μm in at least one plane of the membrane.
Claim 7
Dependent Claim
87 words
A process for preparing a porous regenerated cellulose membrane which comprises casting a cuprammonium solution of cellulose having a viscosity average moecular weight of at least about 5×10 4 in a vapor phase of which at least about 50% of the saturated vapor pressure comprises at least one organic solvent selected from the group consisting of acetone, methyl ethyl ketone, acetaldehyde, trimethylamine, allylamine, isoamylamine, isobutylamine, isopropylamine, ethylamine and propylamine to cause micro-phase separation and regenerating the membrane formed with an acid and washing the membrane with water.
Claim 8
Dependent Claim
87 words
A process for preparing a porous regenerated cellulose membrane which comprises casting a cuprammonium solution of cellulose having a viscosity average moecular weight of at least about 5×10 4 in a vapor phase of which at least about 50% of the saturated vapor pressure comprises at least one organic solvent selected from the group consisting of acetone, methyl ethyl ketone, acetaldehyde, trimethylamine, allylamine, isoamylamine, isobutylamine, isopropylamine, ethylamine and propylamine to cause micro-phase separation and regenerating the membrane formed with an acid and washing the membrane with water.
Claim 9
Dependent Claim
18 words
Process of claim 6 wherein the concentration of the cellulose is 5% by weight to 10% by weight.
Claim 10
Dependent Claim
38 words
Process of claim 6 comprising adding the organic solvent to the cellulose cuprammonium solution in an amount up to the gel point or in an amount of at most 30% by weight based on the cellulose cuprammonium solution.
Claim 11
Dependent Claim
17 words
Process of claim 6 wherein the organic solvent has a boiling point of at most 70° C.
Claim 12
Dependent Claim
16 words
Process of claim 9 wherein the vapor atmosphere of the organic solvent is that of acetone.
Claim 13
Dependent Claim
16 words
Process of claim 9 wherein the vapor atmosphere of the organic solvent is that of trimethylamine.
Claim 14
Dependent Claim
32 words
Process of claim 6 which comprises exchanging the water in the membrane with an organic solvent having a boiling point of at most about 70° C. after washing the membrane with water.
Claim 15
Dependent Claim
14 words
Process of claim 12 wherein the organic solvent is acetone, isobutylamine, isopropylamine or propylamine.
Claim 16
Dependent Claim
10 words
Process of claim 12 wherein the organic solvent is acetone.
Claim 17
Dependent Claim
81 words
Process of claim 6 which comprises immersing the membrane formed in a mixed solution containing at least one organic solvent having no hydroxyl group and a solubility at 20° C. to a 28 % by weight aqueous ammonia solution of at least 10% by weight and not swelling the cellulose after occurrence of micro-phase separation in the cast membrane of the cellulose cuprammonium solution but before exudation of a polymer lean phase after micro-phase separation to the surface of the membrane.
Claim 18
Dependent Claim
16 words
Process of claim 15 wherein the mixed solution is a solution of acetone, ammonia and water.
Claim 19
Dependent Claim
18 words
Process of claim 15 wherein the mixed solution is a solution of methyl ethyl ketone, ammonia and water.
Claim 20
Dependent Claim
31 words
Process of claim 15 which comprises exchanging the water in the membrane with an organic solvent having a boiling point of at most 70° C. after washing the membrane with water.
Claim 21
Dependent Claim
10 words
Process of claim 18, wherein the organic solvent is acetone.
Claim 22
Dependent Claim
55 words
Process of claim 6 which comprises casting the cellulose cuprammonium solution directly into a mixed solution containing at least one organic solvent having no hydroxyl group and a solubility at 20° C. to a 28% by weight aqueous ammonia solution of at least 10% by weight and not swelling the cellulose to cause micro-phase separation.
Claim 23
Dependent Claim
58 words
Process of claim 20, wherein the mixed solution is a solution of the organic solvent, ammonia and water where the concentration of the organic solvent is 10% by weight to 70% by weight based on the weight of the water and that of the ammonia is at most 5% by weight based on the weight of the water.
Claim 24
Dependent Claim
10 words
Process of claim 21, wherein the organic solvent is acetone.
Claim 25
Dependent Claim
31 words
Process of claim 20 which comprises exchanging the water in the membrane with an organic solvent having a boiling point of at most 70° C. after washing the membrane with water.
Claim 26
Dependent Claim
10 words
Process of claim 23, wherein the organic solvent is acetone.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1989-04-07 | 1989-10-07 | 1990-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-07 | 1993-10-07 | 1994-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-07 | 1997-10-07 | 1998-04-08 | $7700.00 | Window Closed / Lapsed |