Patent US1786718A successfully refreshed from Google Patents.
US4743418A
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Process for charge modifying a microporous membrane
Assignee: 3M Purification Inc
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Filing: 1984-08-17
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Granted: 1988-05-10
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Expires: 2004-08-17
Abstract
Abstract A cationic charge modified microporous membrane is provided. The membrane comprises 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
2026-10-28 21:16
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: 24
Claim 1
Independent Claim
131 words
A process for cationically charge modifying a skinless hydrophilic organic polymeric microporous filter membrane having an internal microstructure throughout said membrane comprising bonding a charge modifying amount of a cationic charge modifying agent to substantially all of the membrane microstructure through an aliphatic polyepoxide cross-linking agent having a molecular weight of less than about 500, wherein the charge 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, whereby a skinless hydrophillic organic polymeric microporous filter member is produced having a charge modifying amount of a cationic charge modifying agent bonded to substantially all of the membrane microstructure.
Claim 2
Dependent Claim
131 words
A process for cationically charge modifying a skinless hydrophilic organic polymeric microporous filter membrane having an internal microstructure throughout said membrane comprising bonding a charge modifying amount of a cationic charge modifying agent to substantially all of the membrane microstructure through an aliphatic polyepoxide cross-linking agent having a molecular weight of less than about 500, wherein the charge 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, whereby a skinless hydrophillic organic polymeric microporous filter member is produced having a charge modifying amount of a cationic charge modifying agent bonded to substantially all of the membrane microstructure.
Claim 3
Dependent Claim
139 words
A process for cationically charge modifying a skinless hydrophilic organic polymeric microporous filter membrane having an internal microstructure throughout said membrane, comprising: (a) contacting the membrane with an aqueous solution of a cationic charge modifying agent, wherein the charge 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, (b) contacting the membrane with an aqueous solution of an aliphatic polyepoxide cross-linking agent of less than about 500, whereby a skinless hydrophilic organic polymeric microporous filter membrane is produced having a charge modifying amount of a cationic charge modifying agent bonded to substantially all of the membrane microstructure without substantial pore size reduction or pore blockage.
Claim 4
Dependent Claim
139 words
A process for cationically charge modifying a skinless hydrophilic organic polymeric microporous filter membrane having an internal microstructure throughout said membrane, comprising: (a) contacting the membrane with an aqueous solution of a cationic charge modifying agent, wherein the charge 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, (b) contacting the membrane with an aqueous solution of an aliphatic polyepoxide cross-linking agent of less than about 500, whereby a skinless hydrophilic organic polymeric microporous filter membrane is produced having a charge modifying amount of a cationic charge modifying agent bonded to substantially all of the membrane microstructure without substantial pore size reduction or pore blockage.
Claim 5
Dependent Claim
15 words
The process of claim 2, wherein the contacting step (a) precedes the contacting step (b).
Claim 6
Dependent Claim
15 words
The process of claim 2, wherein the contacting step (b) precedes the contacting step (a).
Claim 7
Dependent Claim
34 words
The process of claim 2, wherein the contacting steps (a) and (b) are combined and the membrane is contacted with an aqueous solution of a mixture of the charge modifying agent and the polyepoxide.
Claim 8
Dependent Claim
24 words
The process of claim 2, wherein the aqueous solutions of charge modifying agent and polyepoxide are produced with water substantially free of ionic content.
Claim 9
Dependent Claim
17 words
The process of claim 6, wherein the water has a resistivity of at least about 250,000 ohm-cm.
Claim 10
Dependent Claim
24 words
The process of claim 2, wherein the aqueous solution of charge modifying agent contains at least about 0.25% amine by weight of the solution.
Claim 11
Dependent Claim
24 words
The process of claim 8, wherein the aqueous solution of the charge modifying agent contains up to 1% amine by weight of the solution.
Claim 12
Dependent Claim
21 words
The process of claim 2, wherein the aqueous solution of polyepoxide contains at least 1% polyepoxide by weight of the solution.
Claim 13
Dependent Claim
22 words
The process of claim 10, wherein the aqueous solution of polyepoxide contains up to about 4% polyepoxide by weight of the solution.
Claim 14
Dependent Claim
22 words
The process of claim 2, wherein the weight ratio of polyepoxide to charge modifying agent is from about 2:1 to about 10:1.
Claim 15
Dependent Claim
16 words
The process of claim 12, wherein the weight ratio is from about 3:1 to about 5:1.
Claim 16
Dependent Claim
13 words
The process of claim 1 or 2, wherein the microporous membrane is nylon.
Claim 17
Dependent Claim
14 words
The process of claim 1 or 2, wherein the microporous membrane is polyhexamethylene adipamide.
Claim 18
Dependent Claim
42 words
The process of claim 1 or 2, 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 19
Dependent Claim
13 words
The process of claim 16, wherein R 1 and R 2 are ethyl.
Claim 20
Dependent Claim
17 words
The process of claim 1 or 2, wherein the amine is tetraethylene pentamine of the formula: ##STR10##
Claim 21
Dependent Claim
16 words
The process of claim 18, wherein the polyepoxide is 1,4-butanediol diglycidyl ether of the formula: ##STR11##
Claim 22
Dependent Claim
15 words
The process of claim 1 or 2, wherein the polyepoxide is a di- or tri-epoxide.
Claim 23
Dependent Claim
19 words
The process of claim 20, wherein the polyepoxide has a molecular weight of from about 146 to about 300.
Claim 24
Dependent Claim
34 words
The process of claim 1 or 2, 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.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-05-10 | 1991-11-09 | 1992-05-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-10 | 1995-11-09 | 1996-05-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-10 | 1999-11-09 | 2000-05-10 | $7700.00 | Window Closed / Lapsed |