Patent GB-856735-A (GB)
Title: Porous and cellular materials
IPC: C08J9/04
Filed: 1957-10-03
Abstract: The invention comprises a cellular or porous material formed from at least one linear, essentially unbranched, head-to-tail polymer of one of, or a copolymer of two or more of, the monomers selected from the group consisting of alphaolefins and conjugated diolefins, or is a copolymer of ethylene and one or more monomers selected from said group.  It may have in admixture therewith anion exchange resin.  The porous structure may be produced by sintering powdered polymer, heating the polymer in admixture with a substance which evolves a gas (e.g. ammonium carbonate, sodium bicarbonate or ammonium nitrate), by leaching soluble matter, by blowing gas through fused and stirred polymer or by vaporising water or other liquid in the polymer.  Pore size can be varied by passing the polymer foam through sieves to fractionate the bubbles.  The products are useful for insulation, floats, laminates, publicity articles, packing, toys, coatings, filter plates and battery separators and ion-exchange diaphragms. Examples show the production by various processes of porous and spongy material from (1) poly propylene, (2) polypropylene mixed with cation or anion exchange resins; (3) and (4) polybutene, (5) polybutadiene (mixed with mineral oils, zinc oxide, sulphur and mercapto-benzothiazole disulphide); (6) a mixture of polypropylene and polybutene; an ethylene propylene copolymer mixed with (7) CuCO3, kaolin, Fe2O3, zinc oxide, blowing agent, sulphur and cumyl peroxide; (8) also with lithopone, mineral oil, synthetic rubber and chlorobutyl peroxide; (9) Cu CO3, Mg O, di Octyl adipate, sulphur and cumyl peroxide.  Specifications 828,791, 834,554, 835,752, 854,615 and 856,733 also are referred to.ALSO:The invention comprises a cellular or porous material formed from at least one linear, essentially unbranched, head-to-tail polymer of one of, or a copolymer of two or more of, the monomers selected from the group consisting of alpha-olefins and conjugated diolefins, or is a copolymer of ethylene and one or more monomers selected from said group.  It may have in admixture therewith an ion exchange resin. The porous structure may be produced by sintering powdered polymer, heating the polymer in admixture with a substance which evolves a gas e.g. ammonium carbonate, sodium bicarbonate or ammonium nitrite, by leaching soluble matter, by blowing gas through fused and stirred polymer or by vaporising water or other liquid in the polymer.  Pore size can be varied by passing the polymer foam through sieves to fractionate the bubbles.  The products are useful for insulation, floats, laminates, publicity articles, packings, toys, coatings, filter plates, battery separators and ion-exchange diaphragms. Examples show the production by the various processes of porous and spongy materials from (1) polypropylene; (2) polypropylene mixed with cation or anion exchange resins; (3) and (4) polybutene; (5) polybutadiene (mixed with mineral oil, zinc oxide, sulphur and mercapto-benzthiazole disulphide); (6) a mixture of polypropylene and polybutene; an ethylene-propylene copolymer mixed with (7) CaCO3, kaolin, Fe2O3, zinc oxide, blowing agent, sulphur and cumyl peroxide; (8) also with lithopone, mineral oil, synthetic rubber and chlorobutyl peroxide; (9) CaCO3, MgO, di-octyl adipate sulphur and cumyl peroxide.  Specifications 828,991, 834,554, 835,752, 854,615 and 856,733 are referred to.