GB741323A - Improvements in and relating to medical and surgical plasters - Google Patents

Abstract

741,323. Adhesive dressings. SMITH & NEPHEW, Ltd., T. J. March 31, 1954 [April 10, 1953], No. 9864/53. Class 81(2). [Also in Group VIII] A bandage or plaster for medical or surgical purposes having a flexible porous backing and a complete non-porous coating of pressuresensitive adhesive on one surface thereof is made sufficiently porous, i.e. a water vapour permeability of 2,000 grms./sq. metre/24 hours, by passing the coated backing under tension over a surface having one or more apertures or slots through which steam under pressure is applied and blown through the pores of the backing from the uncoated side causing bursting of the adhesive to form a multiplicity of small holes therein. The backing may be of natural and/or artificial fibres and the adhesive, which may be medicated, consists of a natural or artificial elastomer, plasticizers, softeners, and tackifiers. The steam treatment may be carried out immediately after coating or after storage. A flexible fabric 8 coated with adhesive on the outer side 9, is passed round pipe 13 having two parallel rows of holes 18 or a slot, Fig. 6 (not shown). Superheated steam under pressure, say 30 or 60 lbs. /sq. inch is supplied to pipe 13. To accommodate different widths of plasters, say 1 inch to 6 inches, pipe 13 having slot 19, Fig. 7, of length slightly more than the maximum plaster width, may have one or more masks 20 to restrict the length of the slot to the required width.