Title: Battery separator manufacturing process

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Claims: The nature and object of the present invention having been completely described and illustrated and the best mode thereof contemplated set forth, what we wish to claim as new and useful and secure by Letters Patent is:

1. A method for producing a battery acid wettable nonwoven battery separator from nonwoven mats of polypropylene thermoplastic fibers, which mats before treatment are not wettable by at least a 35% sulfuric acid battery acid, which method comprises: wetting a nonwoven mat of said thermoplastic fibers with a surfactant-water solution at a temperature of 60.degree. to 170.degree. F., wherein said surfactant is cationic or nonionic and is present as a 0.2 to about 1.0 wt. % solution in said water by contacting only one side of said mat and permitting said solution to spread through said mat; vaporizing the water from the surfactantwater solution within said mat in a hot air countercurrent oven whereby said surfactant is evenly deposited in an amount of 0.3 to 1.0% by weight based on fibers of said nonwoven mat which is now essentially dry; then heating said nonwoven mat to a temperature in excess of the softening point of said thermoplastic fibers but insufficient to melt, shrink or degrade said fibers; and subsequently compressing said heated nonwoven mat to a void fraction of at least 0.4.

2. A method according to claim 1 wherein said nonwoven mat is passed through a mechanical wringer before the vaporizing of the water from the surfactant-water mixture.

3. A method according to claim 1 wherein said compressing includes forming ribs.

4. A method according to claim 1 wherein said nonwoven mat is comprised of polypropylene fibers and is heaed to a temperature of 255.degree. to 300.degree. F and compressed by male and female members heated within the range of 270.degree. to 300.degree. F.

5. A method according to claim 4 wherein said fibers are from 1-10 microns in diameter.
Other info:

Inventors: Buntin, Robert R. (Baytown, TX, US)
Morgan, Walter A. (Baytown, TX, US)

Application Number: 381104
Filing Date: 1973-07-20
Publication_date: 1976-03-30
Assignee: Exxon Research & Engineering Co. (Linden, NJ)
Primary Class(es): 264/137 264/134, 264/136, 264/324, 429/254
Other Classes:
US Patent Ref:

2482062	Sep, 1949	Hanson	136/146.
3084091	Apr, 1963	Volkman	136/148.
3231650	Jan, 1966	Findlay	264/324.
3272657	Sep, 1966	Zenczak	136/148.
3329559	Jul, 1967	Corbin	136/146.
3351495	Nov, 1967	Larsen	136/146.
3354247	Nov, 1967	Zehender	264/119.

Other Refs:
Primary Examiner: Kucia, Richard R.
Assistant Examiner:
Attorney: Myers; K. S., Roth; David A.