Patent GB-1099676-A (GB)
Title: Improvements in or relating to microporous sheet material
Inventor: SHARP FRANK
IPC: D06N3/00
Filed: 1963-11-25
Abstract: Dispersions of a "removable filler," such as NaCl in a solution of a synthetic polymer, are spread on to a substrate, the solvent removed by evaporation and the removable filler leached out by a non-solvent for the polymer.  In examples, the solution is (1) polyurethane rubber in cyclohexanone, (3) P.V.C. in cyclohexanone, (4) polymethylmethacrylate in methylethylketone, (5) polystyrene in toluene, (6) nylon 66 in a mixture of phenol and methanol, (7) an olefin copolymer in xylene, (8) nitrile rubber in cyclohexanone, and (9) a blend of P.V.C. and nitrile rubber in cyclohexanone containing also ZnO and S together with curing accelerators.  The products when removed from the metal or treated paper substrate are microporous and may be useful as filters.  They may be made hydrophilic or hydrophobic by the inclusion of suitable, e.g., silicone surfactants. The film is stretched by friction with the substrate during leaching and this breaks down the encapsulation of the NaCl particles.  The process of the invention may also be used to provide permanent water repellent or waterproof coatings for making waterproofs or for application to a fibrous base in the manufacture of a synthetic leather.  Such a base may be made from a nylon felt impregnated with (Example 11) a cream of P.V.C., polypropylene sebacate, epoxidized oil, solvent naphtha, and a pigment, (12) in addition NaCl, (13) polyurethane rubber dissolved in cyclohexanone, (14) in addition NaCl, (15) a composition containing P.V.C., dioctyl sebacate, a thermal stabilizer sold under the Trade Mark ABRAC, NaCl, solvent naphtha, red, yellow and blue pigments and as wetting agent an Na sulphone succinate ester sold under the Trade Mark MANOXOL TR, and (16) a solution in dimethyl formamide of a polyurethane and a vinyl chloride/vinylidene chloride copolymer in which is dispersed NaCl. The compositions are dried and cured where necessary with mangling and those containing NaCl are leached to produce a porous product. In Example 17, the products of Examples 11-16 are coated with a solution in cyclohexanone of a polyurethane rubber in which is dispersed NaCl.  The product is dried at 100 DEG  C., leached at 50 DEG  C. and dried at 60 DEG  C., and may be lacquered.  The uncoated back of the fibrous base may be grounded, combed or carded.ALSO:Dispersions of a "removable filler" such as NaCl in a solution of a synthetic polymer are spread on to a substrate, the solvent removed by evaporation and the removable filler leached out by a non-solvent for the polymer.  In Examples the solution is (1) polyurethane rubber in cyclohexanone, (3) PVC in cyclohexanone, (4) polymethylmethacrylate in methylethylketone, (5) polystyrene in toluene, (6) nylon 66 in a mixture of phenol and methanol, (7) an olefin copolymer in xylene, (8) nitrile rubber in cyclohexanone, and (9) a blend of PVC and nitrile rubber in cyclohexanone containing also ZnO and S together with curing accelerator.  The products when removed from the metal or treated paper substrate are microporous and may be useful as filters. They may be made hydrophilic or hydrophobic by the inclusion of suitable, e.g. silicone surfactants.  The film is stretched by friction with the substrate during leaching and this breaks down the encapsulation of the NaCl particles.  The process of the invention may also be used to provide permanent water repellent or waterproof coatings for making waterproofs or for application to a fibrous base in the manufacture of a synthetic leather.  Such a base may be made from a nylon felt impregnated with (Example 11) a cream of PVC, polypropylene sebacate, epoxidized oil, solvent naphtha, and a pigment, (12) in addition NaCl, (13) polyurethane rubber dissolved in cyclohexanone, (14) in addition NaCl, (15) a composition containing PVC, dioctyl sebacate, a thermal stabilizer sold under the Trade Mark ABRAC, NaCl, solvent naphtha, red yellow and blue pigments and as wetting agent an Na sulphone succinate ester sold under the Trade Mark MANOXOL TR, and (16) and a solution in dimethyl formamide of a polyurethane and a vinyl chloride/vinylidene chloride copolymer in which is dispersed NaCl.  The compositions are dried and cured where necessary with mangling and those containing NaCl are leached to produce a porous product.  In Example 17 the products of Examples 11-16 are coated with a solution in cyclohexanone of a polyurethane rubber in which is dispersed NaCl.  The product is dried at 100 DEG C, leached at 50 DEG C and dried at 60 DEG C, and may be lacquered. The uncoated back of the fibrous base may be ground, combed or carded. p