| abstract |
Battery separators are formed continuously by placing an aqueous phenolaldehyde resin precursor solution onto a sloped steel or polyfluorocarbon pressure belt which moves upward to a point where it meets another superposed pressure belt of the same material, heating the solution, as it passes through the space between the synchronously moving belts, at a temperature sufficient to cause gellation without loss of water, drying the resulting water-containing sheet after it leaves the confined belt area, curing, and cutting the dry sheet to desired specifications. The resin precursor solution preferably contains resorcinol as well as a thermoplastic resin dispersion. Fillers and fibers may be incorporated. |