Reduktion af materialers åbenhed

摘要

PCT No. PCT/GB94/01236 Sec. 371 Date May 15, 1996 Sec. 102(e) Date May 15, 1996 PCT Filed Jun. 8, 1994 PCT Pub. No. WO94/29525 PCT Pub. Date Dec. 22, 1994A material, which may have a highly open structure such that it has negligible barrier properties, is treated with expandable particles. These are then caused to expand within the material, reducing its openness and improving its barrier properties. The product may be a porous material. The pores may be modified by an agent applied together with the particles or after the expansion. The particles may be thermoplastic microspheres containing gas. The material may be a network material, with a fiber matrix with many voids.