Patent GB-1110016-A (GB)
Title: Absorbent wound dressing with porous readily releasable wound facing
IPC: A61F13/00
Filed: 1965-06-16
Abstract: 1,110,016. Surgical dressings. MINNESOTA MINING & MANUFACTURING CO. 16 June, 1965 [6 July, 1964], No. 25539/65. Heading A5R. [Also in Division B5] A wound dressing capable of absorbing wound exudate without sticking to the wound comprises an absorbent backing for absorbing wound exudate and a thin highly porous, preferably self-sustaining, thermoplastic facing adapted to releasably contact the wound surface. The facing, which is non-absorbent to wound exudate, comprises a discontinuous film having from 10 to 40 pores per square millimetre of film. surface; the pores, which preferably are randomly spaced, have an average area of no more than 0.01 square millimetre (preferably less than 0.005 square millimetre) and constitute from 10 to 40 per cent (preferably from 20 to 30 per cent) of the total area of the facing. As illustrated in Figure 1, the two-layer structure of. absorbent backing and non-absorbent facing is incorporated in an adhesive-tape-supported dressing 10 which comprises a three-layer pad consisting of absorbent backing 11 sandwiched between facing 12 and a retaining sheet 13. To the free surface of the retaining sheet is adhered a layer of tape 8 which extends beyond two opposite edges of the pad, the exposed adhesive surface 9 of the tape being protected by a removable liner 7, which liner also coverts the free surface of the facing prior to use. The absorbent backing preferably is fibrous and may comprise cotton, rayon or cellulosic batts, the preferred material being fibrous batts or wadding of heat-softenable thermoplastic material, for example cellulose acetate. The facing may consist of an inert hydrophobic organic polymer, for example nylon, polyethylene or polypropylene, the latter being preferred. The retaining sheet may be a lightweight web, for example of gauze or viscose, the latter being preferred. As illustrated in Figure 2, the three-layer pad is constructed by passing around a heated drum 19 a fourlayer structure of carrier web 18, precursor 14 for the facing 12, absorbent backing 11 and retaining sheet 13, the carrier web being adjacent the drum. Pressure rollers 20 firmly press the structure against the drum. After the hot-pressed structure has cooled, the carrier web, which may comprise polyester material, silicone-coated cloth or silicone liners, is stripped from the facing. The precursor for the facing consists of a non-woven matting of hydrophobic fibres, which matting previously has been subjected to a low temperature heat treatment to soften and cohere the fibres thereof. The hot pressing causes the fibres of the matting to fuse and coalesce with one another to give a discontinuous film containing numerous irregularly shaped small openings and the fibres of the absorbent backing to embed within the facing thereby to unite the absorbent backing and the facing. Alternatively, the facing and the absorbent backing may be formed separately and thereafter united by heat treatment. In place of the retaining sheet, the free surface of the absorbent backing may be covered with a facing as above described or with a continuous impermeable film.