Process for reinforcing structurally fragile inorganic fabrics
AssigneeHughes Aircraft Company
InventorsHong S. Lim, Howard H. Rogers, Scott A. Verzwyvelt
Life of this patent
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Abstract
Chemically stable polymers in aqueous alkaline solutions are dissolved in a strongly polar solvent, thoroughly dispersed from this solvent into and throughout the interstices of porous inorganic fabrics and subsequently separated from said solvent by precipitation to provide a homogeneous reinforcement of the structural properties of said fabrics.
Claims10
A process for reinforcing a porous fragile inorganic fabric to increase its mechanical strength without inhibiting the flow of gases there through or decreasing the wettability of said fabric comprising the steps of:
- (a) first providing an impregnation solution of a thermosetting polymer and a strongly polar solvent;
- (b) immersing said fabric in said solution until said fabric is saturated with said solution;
- (c) removing said saturated fabric from said solution and blotting to remove excess solution from said fabric;
- (d) causing said polymer to precipitate inside of the pores of said fabric from said solution, by treating said impregnated fabric with a hot liquid extractant characterized by exhibiting the property of being miscible with said polar solvent and immiscible with said polymer, thereby forming polymer particles about the fibers of said fabric which reinforce but do not coat said fabric;
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- (e) removing said particle reinforced cloth from said liquid extractant and exposing said cloth to the drying action of hot air until dry.
A process for preparing a high mechanical strength separator suitable for use in an alkaline storage battery such as nickel-cadium and nickel-hydrogen space batteries characterized in that said separator is wettable with aqueous alkali solution and permeable by gases comprising the steps of:
- (a) providing a porous inorganic fabric selected from the group exhibiting chemical resistance to alkali solutions and good thermal stability.
- (b) saturating said fabric with an impregnation solution comprising a polymer selected from the group consisting of polysulfone, polybenzimidazole, polybenzoxazole and polybenzothiazole dissolved in a polar solvent;
- (c) removing any excess impregnation solution from said saturated fabric by blotting said saturated fabrics;
- (d) immersing said fabric into a hot extractant selected from the group of liquids consisting of water, low carbon chain alcohols, acetone and mixtures thereof thereby causing said polymer to precipitate from said solution and be retained as discontinuous polymer particles throughout the pores of said fabric while said polar solvent is absorbed by said extractant, and
- (e) causing said extractant containing said polar solvent to be removed from said fabric by exposing said fabric to an elevated temperature not to exceed 100.degree. C. until dry.
A process for reinforcing woven zirconium-oxide-yttrium oxide fabrics to render said fabrics suitable for use as battery separators in alkali storage batteries intended for space applications where gases are evolved which must flow through said separators comprising the steps of:
- (a) first providing an impregnation solution of a polymer selected from the group consisting of polysulfone, polybenzimidazole, polybenzoxazole, polyether, and polybenzothiazole, and a strongly polar solvent;
- (b) immersing said fabric in said solution until said fabric is saturated with said solution;
- (c) removing said saturated fabric from said solution and blotting said fabric to remove excess solution from said fabric;
- (d) immersing said fabric into a hot extractant selected from the group of the liquids consisting of water, low carbon chain alcohols, acetone and mixtures thereof thereby causing said polymer to precipitate from said solution and be retained throughout the pores of said fabric while said polar solvent is absorbed by said extractant;
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- (e) causing said extractant containing said polar solvent to be removed from said fabric by exposing said fabric to an elevated temperature not to exceed 100.degree. C. until dry.
Dependencies are inferred from the claim text.