Process of manufacturing a microporous sheet material
AssigneeEvans Products Company
InventorsJames Young, Charles H. Geissel, Piotr Zenczak
Life of this patent
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Abstract
A process of manufacturing a microporous sheet by forming a blend of a polyolefin, silica and a water insoluble plasticizer, forming a sheet from the blend, and contacting the sheet with water for a time sufficient to render the sheet microporous. The plasticizer, being essentially insoluble in water, is easily separated therefrom and recycled. The preferred plasticizers are dialkyl phthalates and dialkyl adipates having between about two and about eleven carbon atoms in the oxo-alcohol moiety.
Claims14
A process of manufacturing a microporous sheet comprising:
- plasticating a blend comprising a polyolefin selected from the group consisting of homopolymers and copolymers of ethylene, propylene and buylene, and mixtures thereof;
- finely divided silica;
- and a substantially water-insoluble plasticizer selected from the group consisting of dialkyl phthalates and dialkyl adipates having between about two to eleven carbon atoms in the oxo-alcohol moiety;
- forming a sheet from the plasticated blend;
- and contacting the sheet with water for a period of time sufficient to remove an amount of the plasticizer from the sheet sufficient to render the sheet microporous.
The process of forming a microporous battery separator comprising:
- plasticating a blend comprising a polyolefin selected from the group consisting of homopolymers and copolymers of ethylene, propylene and buylene, and mixtures thereof;
- finely divided silica;
- and a substantially water-insoluble plasticizer selected from the group consisting of dialkyl phthalates and dialkyl adipates having between about 2 and about 11 carbon atoms in the oxo-alcohol moiety;
- forming a sheet from the plasticated blend;
- contacting the sheet with water for a period of time sufficient to remove an amount of the plasticizer from the sheet sufficient to render the sheet microporous;
- drying the sheet;
- and cutting the sheet into a size suitable for separating the plates in a battery.
Dependencies are inferred from the claim text.