Battery separator manufacturing process

Claim 3

The method of claim 1 wherein said mixture is subjected to a temperature sufficient to at least partially degrade said polymeric resin prior to extrusion, said fibers are attenuated immediately after extrusion in a hot air stream and collected in a mat, said mat is coated with said second wetting agent which is classified as water soluble and oil insoluble, said mat is thereafter heated to between the softening point and melting point of said polymeric resin And compacted to develop said first wetting agent which is classified as oil soluble and water insoluble and is soluble in admixture with said polymeric resin at the resin''s fiber forming extrusion temperature but insoluble at room temperature.

Claim 4

The method of claim 2 wherein said polymeric resin is polypropylene, the first said wetting agent is a phenol surfactant containing 1-15 moles of ethylene oxide included in an amount of 1-10 percent by weight based on the weight of the resin and the second said wetting agent is chosen from the group consisting of anionic surfactants, nonionic surfactants and mixtures thereof, said resin and wetting agent mixture is heat treated at a temperature between 600*-900*F before extrusion, said attenuation is to a diameter of 1-10 microns and said fibers are collected on a continuously moving take-up device positioned 1-18 inches from the die openings after attenuation to form a nonwoven mat 20-100 mils in thickness with a basis weight between 10-500 grams per square meter, the second said wetting agent being applied to said mat in excess in a carrier solution and said excess being removed by passing the nonwoven mat with said wetting agent therein through wringer rolls spaced about 10-20 percent of the dry mat thickness apart and removing the excess carrier solution to a remaining level of about 60-80 percent liquid by weight per unit weight of dry mat and thereafter driving off the carrier with hot air, thereafter heating said mat to 220*-320*F and compressing said heated mat to 10-20 mils thickness, a pore size of less than 20 microns and a porosity of greater than 50 percent in a gap of 4-5 microns at a pressure of less than 10 psi with a first said wetting agent retention of 65 percent + or - 5 percent.

Claim 5

The method of claim 3 wherein said fibers have a diameter of about 1 5 microns and said phenol surfactant is chosen from the group consisting of a nonylphenol having 4 moles of ethylene oxide and a dodecylphenol having 5 moles of ethylene oxide, and said second wetting agent is an aliphatic ethoxylated organic acid phosphate and said carrier is water and said basis weight is between 20 and 300 grams per square meter, and said heating of said mat is to 255*-265*F.

Claim 8

The method of claim 5 wherein the first said wetting agent is relatively water insoluble and said second wetting agent is relatively water soluble and the development increases the bonding of the fibers together.

Claim 9

The method of claim 5 wherein the first said wetting agent is classified as oil soluble and water insoluble and said second wetting agent is classified as water soluble and oil insoluble, the fibers are formed into a nonwoven mat and a carrier with the second wetting agent therein is applied in liquid form in excess and the excess is removed by passing the nonwoven mat through wringer rolls after which said carrier is vaporized depositing said wetting agent on the fibers.

Claim 10

The method of claim 7 wherein said wetting agent containing fibers are attenuated to a diameter of 0.05-50 microns in a hot air stream after said extrusion and collected on a continuously moving take-up device positioned from 1-30 inches from the die openings to form said nonwoven mat, said fibers being collected in a mat thickness of 20-200 mils with a basis weight between 10 and 500 grams per square meter, said wringer rolls being spaced apart about 10-20 percent of the dRy mat thickness and removing the excess carrier and wetting agent to a remaining level of about 60-80 percent liquid by weight per unit weight of dry mat.

Claim 11

The method of claim 8 wherein after said carrier is water the water solution of the second wetting agent is composed to deposit from 0.3-1.0 percent wetting agent on said mat based on the weight of the mat when said water has been vaporized, said mat is compressed to a thickness of 5-50 mils and to a pore size of less than 40 microns with a porsity retention of at least 40 percent in a gap between 4-5 microns with a pressure of less than 10 psi, said resin is a C3 to C8 polyolefin thermoplastic and said mat is heated to between the softening point and melting point of the resin prior to compression.

Claim 12

The method of claim 5 wherein said resin is a C3 to C8 polyolefin, the first said wetting agent is soluble in admixture with said resin at the resin''s fiber forming extrusion temperature but insoluble at room temperature and wherein after said second wetting agent has been coated on said fiber the first said wetting agent is developed by means of heat and pressure.