Patent GB-798471-A (GB)
Title: Surgical dressings
Inventor: DAVIES THOMAS PARRY
IPC: A61L15/26
Filed: 1953-10-12
Abstract: A surgical dressing comprises a porous fibrous material which has been treated with polythene, a vinyl polymer, a polyester or a polyamide by impregnating the material with an aqueous dispersion of the polymer followed by drying, whereby the polymer is deposited on the material in particulate form, one or both surfaces of the dressing being free from projecting fibres. Specified fibrous materials include carded webs of fibres, woven fabrics and non-woven fabrics.  The vinyl polymer may be polyvinyl chloride, polyvinyl acetate, or a copolymer of vinyl chloride and vinyl acetate.  A silicon resin may be applied in admixture with the polymer.  The fibre-free surface is obtained by hot-pressing after drying the impregnated material.  After impregnation of the material with the aqueous dispersion, partial drying may be effected by passing the material over a stack of steam-heated rolls.  The material may then be passed through a bath containing hot water to wash off as completely as possible the emulsifying agent employed, and may then be passed over further steam-heated rolls for complete drying.  After this it is passed through a hot calendar, whereby a smooth surface free from projecting fibres is obtained.  In examples, an intermittently bonded non-woven fabric is impregnated with a polythene dispersion, the fabric is partially dried, washed in hot water, and then dried completely over steam-heated rolls.  Pieces of washed and dried fabric are then (a) interleaved with regenerated cellulose film, rolled under tension and then heated at 120 DEG  C. for 30 minutes, and (b) plied with a sheet of the same initial non-woven fabric on the one side and with a sheet of regenerated cellulose film on the other side, rolled on a core under tension and then heated in steam at 25 lbs. pressure per square inch for 30 minutes.  Specification 468,529, [Group VIII], is referred to.ALSO:A surgical dressing comprises a porous fibrous fabric treated with polythene, a vinyl polymer, a polyester, or polyamide, by impregnating the fabric with an aqueous dispersion of the material followed by drying whereby the material is deposited on the fabric in particulate form, one or both surfaces of the dressing being free from projecting fibres.  Specified fibrous fabrics are absorbent paper, carded webs of fibres, woven fabrics and non-woven fabrics. The vinyl polymer may be polyvinyl chloride, polyvinyl acetate, or a copolymer of vinyl chloride and vinyl acetate.  A silicone resin may be applied in admixture with the film forming material.  The fibre free surface is obtained by hot-pressing after drying the impregnated material.  After impregnation of the fabric with an aqueous dispersion partial drying may be effected by passing the material over a stack of steam-heated rolls.  The fabric may then be passed through a bath containing hot water to wash off as completely as possible the emulsifying agent employed, and then be passed over further steam-heated rolls for complete drying.  After this it is passed through a hot calendar whereby a smooth surface free from projecting fibres is obtained.  Alternatively after washing and drying, the fabric may be interleaved with a single ply of an inert flexible film, such as regenerated cellulose, and rolled under tension upon a core.  The roll is then heated sufficiently to cause fusion of the polythene or like plastic deposited on the fabric.  On cooling, the treated fabric has a smooth fibre-free surface on both sides, the interleaving film being lightly anchored to one side as a protective coating.  As a further alternative, after washing and drying, the fabric may be plied with a sheet of non-woven or woven fabric or a carded web of absorbent fibres or a sheet of absorbent paper and then passed through smooth steam-heated rolls; or it may be plied with a sheet of absorbent fibrous material on one side and with a sheet of regenerated cellulose or other flexible film on the other side, then wound on a core under tension and heated to produce the necessary fusion.  The amount of polythene applied to the fabric may range from 50 per cent to 600 per cent based on the weight of the initial fabric.  In examples an intermittently bonded non-woven fabric is impregnated with a polythene dispersion, the fabric is partially dried, washed in hot water, and then dried completely over steam-heated rolls.  Pieces of washed and dried fabric are then (a) interleaved with regenerated cellulose film, rolled under tension and then heated at 120 DEG  C. for 30 mins.; and (b) plied with a sheet of the same initial non-woven fabric on the one side and with a sheet of regenerated cellulose film on the other side, rolled on a core under tension and then heated in steam at 25 lb. pressure per square inch for 30 mins. Specification 468,529, [Group VIII], is referred to.