Barrier products

Abstract From the Canadian patent

Abstract, A porous material (e.g. a paper) has pores with a range of sizes. A pore modifying agent (comprising particles of a narrow size range) is selectively incorporated within the larger pores to provide zones of high surface area. These greatly reduce the penetrability of the material (e.g. by micro-organisms) while having relatively little effect on its air-permeability. The modifying agent may be incorporated by creating a pressure difference across the material, and treating it with a dispersion (e.g. an aerosol) of the modifying agent under, conditions of low inertia, and incorporating only a small amount of the agent (e.g. under 1% w/w).