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US4473475A Expired / Lapsed US ⏱️ 0.0 years remaining

Charge modified microporous membrane, process for charge modifying said membrane, and process for filtration of fluids

Assignee: 3M Purification Inc
•
Filing: 1981-05-29
•
Granted: 1984-09-25
•
Expires: 2001-05-29
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Abstract

Abstract A cationic charge modified microporous membrane is provided. The membrane comrises a hydrophilic organic polymeric microporous membrane having bonded thereto, through a cross-linking agent, a charge modifying amount of a cationic charge modifying agent. The charge modifying agent is an aliphatic amine or polyamine, preferably tetraethylene pentamine, and the cross-linking agent is an aliphatic polyepoxide having a molecular weight of less than about 500, preferably 1, 4 butanediol diglycidyl ether. The microporous membrane is preferably nylon. The process for applying the charge modifying agent to the membrane, preferably comprises contacting the membrane with an aqueous solution of the charge modifying agent and then contacting the membrane with a substantially aqueous solution of the cross-linking agent. The preferred process uses high purity water, i.e. water having no significant ionic content, to produce a membrane suitable for use in filtering ultra pure (18 megohm-cm resistivity) water for use in producing electronic devices. Such a membrane exhibits an advantageously low "flush-out" time compared to known cationic charge modified microporous membranes and unmodified microporous membranes.

Inventors

  • 👤 Robert G. Barnes, Jr.
  • 👤 Chaokang Chu
  • 👤 George T. Emond
  • 👤 Asit K. Roy

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-24 01:49
CPC Classifications
B; B01; B01D; B01D67/00; B01D67/0081; B01D67/0093; B01D67/00931; B01D71/00; B01D71/06; B01D71/56; B01D2323/00; B01D2323/30

Claims Analysis

Total Claims: 12
Claim 1
Independent Claim 128 words
A process for the filtration of liquids having particulate contaminants therein, comprising passing the liquid through a hydrophilic cationic charge modified microporous filter membrane comprising: a hydrophilic organic polymeric microporous filter membrane having an internal micro-structure throughout said membrane, and a charge modifying amount of a cationic charge modifying agent bonded to substantially all of the membrane micro-structure without substantial pore size reduction or pore blockage, through an aliphatic polyepoxide cross-linking agent having a molecular weight of less than about 500, wherein the charge and modifying agent is selected from the group consisting of: (i) aliphatic amines which are polyamines having at least one primary amine or at least two secondary amines; and (ii) aliphatic amines having at least one secondary amine and a carboxyl or hydroxyl substituent.
Claim 2
Dependent Claim 128 words
A process for the filtration of liquids having particulate contaminants therein, comprising passing the liquid through a hydrophilic cationic charge modified microporous filter membrane comprising: a hydrophilic organic polymeric microporous filter membrane having an internal micro-structure throughout said membrane, and a charge modifying amount of a cationic charge modifying agent bonded to substantially all of the membrane micro-structure without substantial pore size reduction or pore blockage, through an aliphatic polyepoxide cross-linking agent having a molecular weight of less than about 500, wherein the charge and modifying agent is selected from the group consisting of: (i) aliphatic amines which are polyamines having at least one primary amine or at least two secondary amines; and (ii) aliphatic amines having at least one secondary amine and a carboxyl or hydroxyl substituent.
Claim 3
Dependent Claim 14 words
The process of claim 1, wherein the hydrophilic organic polymeric microporous membrane is nylon.
Claim 4
Dependent Claim 15 words
The process of claim 1, wherein the hydrophilic organic polymeric microporous membrane is polyhexamethylene adipamide.
Claim 5
Dependent Claim 40 words
The process of claim 1, wherein the charge modifying agent is an amine of the formula: ##STR9## wherein R 1 and R 2 are alkyl of 1 to 4 carbon atoms and x is an integer from 0 to 4.
Claim 6
Dependent Claim 13 words
The process of claim 4, wherein R 1 and R 2 are ethyl.
Claim 7
Dependent Claim 15 words
The process of claim 4, wherein the amine is tetraethylene pentamine of the formula: ##STR10##
Claim 8
Dependent Claim 18 words
The process of claim 1 or 6, wherein the polyepoxide is 1,4-butanediol diglycidyl ether of the formula: ##STR11##
Claim 9
Dependent Claim 13 words
The process of claim 1, wherein the polyepoxide is a di- or tri-epoxide.
Claim 10
Dependent Claim 21 words
The process of claim 1 or 8, wherein the polyepoxide has a molecular weight of from about 146 to about 300.
Claim 11
Dependent Claim 32 words
The process of claim 1 wherein the polyepoxide has the formula: ##STR12## wherein R is an alkyl of 1 to 6 carbon atoms and n is an integer from 2 to 3.
Claim 12
Dependent Claim 17 words
The process of claim 1, wherein the liquid is water having at least about 18 megohm-cm resistivity.

References Cited (Backward Citations)

US2782884A Cited
US3152061A Cited
US3642668A Cited
US3567631A Cited
US3876738A Cited
US3892665A Cited
US4265745A Cited
US4305782A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1987-09-25 1988-03-26 1988-09-25 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1991-09-25 1992-03-26 1992-09-25 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1995-09-25 1996-03-26 1996-09-25 $7700.00 Window Closed / Lapsed

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