US4361632A — Alkaline battery, composite separator therefor

Claim 1

Independent Claim 285 words

An improved composite absorber/barrier battery separator for use in an alkaline battery cell for physically separating electrodes of said cell and for controlling the transfer of ions in an electrolyte solution during cell operation, in which said composite separator includes an absorber comprised of a flexible and fibrous substrate, resistant to strong alkali and oxidation while holding electrolyte in contact with said electrodes during electrolyte ion transfer, said improvement comprising: a moderately cured polyvinyl alcohol film adhered to at least one side of said absorber prepared from an aqueous coating composition comprising of: (a) a polyvinyl alcohol aqueous dispersion comprised of (1) a noncrosslinked polyvinyl alcohol solution, (2) inert hydrophilic fillers (3) a dispersing agent, (4) a water soluble plasticizer, and (5) a low molecular weight alcohol-water mixture; and (b) a crosslinking agent admixture comprised of; (1) a crosslinking agent, and (2) a catalyst; said dispersion and said admixture being characterized by having an insitu crosslinking property for forming a matrix of polyvinyl alcohol molecules which is insoluble in alkaline electrolyte, said crosslinking property being activated when said coating composition is cured at a desired temperature to moderately crosslink the polyvinyl alcohol with the crosslinking agent, said matrix of polyvinyl alcohol molecules being a semi-permeable film which mechanical bonds to said web along a interface of said film and said absorber web, said interface being a region formed of a portion of said film physically entangled with a portion of said web, having a thickness which is sufficiently small with respect to the thickness of said film, so as to substantially preclude delays in transitions from hydrodynamic flow through the absorber to diffusional flow through said film of electrolyte ions and masses during cell operations.

Claim 2

Dependent Claim 285 words

An improved composite absorber/barrier battery separator for use in an alkaline battery cell for physically separating electrodes of said cell and for controlling the transfer of ions in an electrolyte solution during cell operation, in which said composite separator includes an absorber comprised of a flexible and fibrous substrate, resistant to strong alkali and oxidation while holding electrolyte in contact with said electrodes during electrolyte ion transfer, said improvement comprising: a moderately cured polyvinyl alcohol film adhered to at least one side of said absorber prepared from an aqueous coating composition comprising of: (a) a polyvinyl alcohol aqueous dispersion comprised of (1) a noncrosslinked polyvinyl alcohol solution, (2) inert hydrophilic fillers (3) a dispersing agent, (4) a water soluble plasticizer, and (5) a low molecular weight alcohol-water mixture; and (b) a crosslinking agent admixture comprised of; (1) a crosslinking agent, and (2) a catalyst; said dispersion and said admixture being characterized by having an insitu crosslinking property for forming a matrix of polyvinyl alcohol molecules which is insoluble in alkaline electrolyte, said crosslinking property being activated when said coating composition is cured at a desired temperature to moderately crosslink the polyvinyl alcohol with the crosslinking agent, said matrix of polyvinyl alcohol molecules being a semi-permeable film which mechanical bonds to said web along a interface of said film and said absorber web, said interface being a region formed of a portion of said film physically entangled with a portion of said web, having a thickness which is sufficiently small with respect to the thickness of said film, so as to substantially preclude delays in transitions from hydrodynamic flow through the absorber to diffusional flow through said film of electrolyte ions and masses during cell operations.

Claim 3

Dependent Claim 35 words

A separator in accordance with claim 1, wherein said noncrosslinked polyvinyl alcohol is a medium viscosity polymer within the group of polyvinyl alcohol polymers with high percentages of hydrolysis levels of between 98 and 100%.

Claim 4

Dependent Claim 44 words

A separator in accordance with claim 1, wherein said inert fillers are powdered or fibrous and are selected from the group consisting of kaolin clays, metallic oxides, titanates and silicate of a suitable size and wherein said fillers are substantially insoluble in alkaline electrolyte.

Claim 5

Dependent Claim 28 words

A separator in accordance with claim 1 wherein said dispersing agent is a salt or ester of a sulfonic acid which is nonreactive and nonoxidizable in alkaline electrolyte.

Claim 6

Dependent Claim 28 words

A separator in accordance with claim 1, wherein said water soluble plasticizer is selected from the solid and liquid polymer glycol groups consisting of methoxylated and ethoxylated glycols.

Claim 7

Dependent Claim 41 words

A separator in accordance with claim 1, wherein said crosslinking agent is selected from dialdehyde, boron compound and metal oxide groups consisting of aliphatic, furyl and aryl dialdehydes, oligo aldehydes, glyoxylic acid (OHC--COOOH) and analogs, substituted benzaldehydes, and acetaldehyde derivitives acrolein.

Claim 8

Dependent Claim 22 words

A separator in accordance with claim 1, wherein the alcohol in the alcohol-water mixture is isopropyl alcohol useful for controlling coating rheology.

Claim 9

Dependent Claim 14 words

A separator in accordance with claim 1, wherein said catalyst is diluted sulfuric acid.

Claim 10

Dependent Claim 66 words

A separator in accordance with claim 8, wherein said polyvinyl alcohol coating composition is comprised of from 0 to 400 dry parts of said inert filler, from 1 to 10 dry parts of said dispersing agent, from 0-40 dry parts of said plasticizer, from 1-20 dry parts of said crosslinking agent; and wherein each of said dry parts being based on 100 parts of polyvinyl alcohol.

Claim 11

Dependent Claim 33 words

A separator in accordance with claim 9, wherein the pH of said polyvinyl alcohol coating composition is adjusted to a range between 4 and 5 to increase the rate of the crosslinking reaction.

Claim 12

Dependent Claim 24 words

A separator in accordance with claim 10, wherein said film has a basis weight ranging from 20 gm/m 2 to 150 gm/m 2 .

Claim 13

Dependent Claim 19 words

A separator in accordance with claim 11, wherein the area resistivity is from 0.2 to 0.6 ohm-cm 2 .

Claim 14

Dependent Claim 19 words

A separator in accordance with claim 1 wherein the caliper of said absorber web is 10.0 to ±0.5 mils.

Claim 15

Dependent Claim 43 words

A separator in accordance with claim 1, wherein said crosslinking agent admixture is a crosslinking agent selected from boron oxides, boric and metaboric acids and the salts of each of them, magnesium oxide, calcium oxide, titanium oxide, zirconium oxide, aluminum oxide and Beta-alumina.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1985-11-29	1986-05-31	1986-11-30	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1989-11-29	1990-05-31	1990-11-30	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1993-11-29	1994-05-31	1994-11-30	$7700.00	Window Closed / Lapsed

Alkaline battery, composite separator therefor

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