Method of producing self-bonded, melt-blown battery separators, and resulting product

Abstract

Abstract The disclosure relates to the production of multi-ply battery separators utilizing mats of melt-blown, randomly laid, self-bonded thermoplastic resin fibers. The process involves the production of at least three separate plies of self-bonded, melt-blown thermoplastic fibers, which are joined in the absence of separate adhesive materials to form a cohesive, multi-ply material. The multi-ply material comprises an internal structure having fiber size, porosity and other characteristics particularly suitable for use in lead-acid battery separator application. The outer plies are formed to have characteristics more suitable for strength and abrasion resistance. In the process of the invention, the several plies are separately formed by melt-blowing techniques, in themselves known, and the several plies are joined in the presence of heat and/or heat and pressure, forming a multi-ply structure entirely free of external adhesive material. The thus-formed multi-ply web is then impregnated with an appropriate wetting agent in liquid solution. Before use, the web material is dried. Importantly, however, the impregnated web before drying is subjected to substantial heat and localized rolling pressure, not only to mechanically disperse the wetting agent, but simultaneously to flash off most of the solvent or carrier, in advance of the basic drying step. Ideally, the mechanical dispersal and flashing off of the wetting agent is accomplished in conjunction with the formation of ribs under heat and pressure in the thermoplastic mat. After being cut to size, the multi-ply mat is folded about the bottom edge of a battery separator plate and thermally sealed along the side edges, forming a complete envelope.

Inventors

• 👤 Roy G. Volkman

Bibliographic Details