Impact modified polystyrene gaskets for electrochemical cells

Details Impact modified polystyrene gaskets for electrochemical cells Impact modified polystyrene gaskets for electrochemical cells

1999-07-20

2001-12-04

Brouillette, Gabrielle (Department: 1745)

Chemistry: electrical current producing apparatus, product, and

Means externally releasing internal gas pressure from closed...

Elastic, resilient or spring biasing valve means

C429S053000, C429S006000

Reexamination Certificate

active

06326099

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to improved gaskets for electrochemical cells, more particularly to non-ventable gaskets for electrochemical cells.
BACKGROUND OF THE INVENTION
Electrochemical cells, such as miniature alkaline air cells, are stable, high-energy sources for electrical devices such as hearing aids. An alkaline electrolyte must be sealed within the confines of a miniature alkaline air cell to prevent corrosive damage to the exterior of the cell and possibly to the electrical device in which it is housed, while a continuous supply of air must be provided to the surface of the air electrode.
Generally, a miniature alkaline air cell comprises an outer metal container having at least one air opening in its base to provide air to the active air electrode, a hydrophobic film layer, an air electrode, a separator layer, an anode mask, and an electrolyte. The cell assembly is capped with a gasket and metal cell cover which seals the open end of the cell container thereby sealing in the alkaline electrolyte. The term “gasket” as used herein refers to a non-ventable sealing member for providing a fluid-tight joint between battery components. Gaskets for alkaline air cells have generally been made from nylon, polypropylene or polysulphone, with nylon being preferred, especially nylon 66. However, nylon gaskets for miniature alkaline air cells have major disadvantages. First, nylon absorbs moisture making it susceptible to hydrolytic degradation in a corrosive electrolyte. As a result of the tendency for nylon to absorb moisture, it must be dried prior to molding. After molding, the dimensions and properties of the resulting nylon gasket are affected by the tendency of nylon to absorb moisture. Hydrolytic degradation of nylon occurs through chain scission of amide bonds. Chain scission embrittles the nylon gasket making it susceptible to stress cracking, which leads to gasket failure and leakage of electrolyte from the cell.
SUMMARY OF THE INVENTION
The inventor has discovered that an electrochemical cell having a gasket formed of a styrenic polymer blend is less sensitive to moisture and hydrolytic degradation. As a result, the use of a gasket which is formed of a styrenic polymer blend provides an electrochemical cell which is substantially less likely to exhibit electrolyte leakage on account of gasket failure.


REFERENCES:
patent: 4343869 (1982-08-01), Oltman et al.
patent: 4404266 (1983-09-01), Smilanich
patent: 5395890 (1995-03-01), Nakano et al.
patent: 5908898 (1999-06-01), Wan-Cheng et al.
patent: 874408 (1998-04-01), None
patent: 6-203814 (1994-07-01), None
patent: 7-53815 (1995-02-01), None
patent: 9-180689 (1997-07-01), None
patent: 10-100224 (1998-04-01), None
patent: WO 94/22175A (1994-09-01), None

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