# US 4,397,908 A · Electrically neutral nonpermselective porous membrane

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- Number: US 4,397,908 A
- Document ID: US4397908A
- Status: Granted
- Kind: A
- Application number: 06/299,574
- Filed: 1981-09-04
- Granted: 1983-08-09
- Earliest claimed: 1979-12-03
- Assignees: Sybron Corporation
- Inventors: Edward L. Phillips
- Web page: https://patentgrep.com/patent/US4397908A

## CPC

- C25D 13/22: Servicing or operating {apparatus or multistep processes}
- B01D 69/141: {Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes}
- B01D 71/301: {Polyvinylchloride}
- B01D 71/16: Cellulose acetate
- Y10T 442/2139: Coating or impregnation specified as porous or permeable to a specific substance [e.g., water vapor, air, etc.]
- Y10T 442/2762: Coated or impregnated natural fiber fabric [e.g., cotton, wool, silk, linen, etc.]
- Y10T 442/277: Coated or impregnated cellulosic fiber fabric
- Y10T 442/2885: Coated or impregnated acrylic fiber fabric
- Y10T 442/2893: Coated or impregnated polyamide fiber fabric
- Y10T 442/291: Coated or impregnated polyolefin fiber fabric
- Y10T 442/2918: Polypropylene fiber fabric
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- 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)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A nonpermselective porous membrane sheet, which comprises a natural or synthetic fiber material substrate having coated thereon a mixture of a plastic binder material and a non-ion exchangeable filler material, said membrane being capable of transmitting negatively and positively charged ions between the electrodes in an electrodeposition painting operation and at the same time capable of preventing backflow of the electrolytes between the electrode chambers.

## Claims

### Claim 1

An electrically neutral nonpermselective porous membrane suitable for use in an electrodeposition system which exhibits a comparative acid removal number of from about 250 to 400 milli equivalents which comprises a woven fabric substrate having coated thereon a mixture of a binder material and a non-ion exchangeable inert porous filler material in a filler to binder weight ratio of 0.8:1 to 5:1, wherein the binder comprises at least one material selected from the group consisting of polyvinylchloride, polyvinylidene chloride, polyvinylidene fluoride, polyvinyl acetate, cellulose acetate, polyacrylonitrile, acrylic polymers and stryene polymers; and the filler comprises at least one material selected from the group consisting of macroporous crosslinked styrene based polymers, gel type crosslinked styrene based polymers, wood, starch, sugar, flour, natural gum, gelatin, and cellulose, with the porosity of said filler material forming a plurality of random paths which pass through the thickness of the membrane, with said membrane being capable of transmitting negatively and positively charged ions between the electrodes in an electrodeposition painting operation and at the same time capable of preventing backflow of the electrolytes between the electrode chambers.

### Claim 2 (depends on 1)

The membrane of claim 1 in which the fabric substrate comprises a synthetic material.

### Claim 3 (depends on 2)

The membrane of claim 2 in which the synthetic material comprises at least one material selected from the group consisting of polypropylene, polyesters, acrylics, saran, polyvinyl chloride, polyethylene and polyamide.

### Claim 4 (depends on 1)

The membrane of claim 1 in which the fabric substrate is made up of a natural fiber.

### Claim 5 (depends on 4)

The membrane of claim 4 in which the natural fiber comprises at least one material selected from the group consisting of cotton, wool, flax and silk.

### Claim 6 (depends on 1)

The membrane of claim 1 in which the fabric substrate comprises a blend of synthetic and a natural fiber.

### Claim 7

An electrically neutral nonpermselective porous membrane suitable for use in an electrodeposition system which exhibits a comparative acid removal number of from about 250 to 400 milli equivalents which comprises a woven polypropylene fabric substrate having coated thereon a mixture of polyvinylidene fluoride binder material and a non-ion exchangeable inert porous filler material in a filler to binder weight ratio of 0.8:1 to 5:1, with the porosity of said filler material forming a plurality of random paths which pass through the thickness of the membrane, with said membrane being capable of transmitting negatively and positively charged ions between the electrodes in an electrodeposition painting operation and at the same time capable of preventing backflow of the electrolytes between the electrode chambers.