| abstract |
A pressure-sensitive adhesive material made of an elastic mixture comprising a continuous phase formed from a physically cross-linked solid rubber such as a styrene-olefin-styrene block copolymer, for example a styrene-isoprene-styrene block copolymer, and a compatible liquid rubber, such as a liquid styrene-isoprene, and a discontinuous phase substantially comprised of one or more "swellable polymers", absorbents that are swellable in water. Additives such as polybutenes, polyisobutylene, mineral oil, stabilizers and other rubbers, may be present. Water soluble polymers may be added to the swellable absorbents to form part of the discontinuous phase. The pressure-sensitive adhesives the advantage over the prior are that they avoid the need to include materials known to irritate skin and mucous membranes. In particular, prior art compositions have needed to include substantial quantities of tackifying resins, which could cause problems particularly in wound dressings. The preferred compositions of the invention include no resins although minor amounts of up to 15 wt. %, preferably not more than 5%, of resinous materials may be included. The adhesive layer can be combined with a non-adhesive, water impervious film and can be used in wound care, ostomy care and in other medical products. |