Pressurizable envelope and method

Abstract

An internally pressurizable lightweight high tensile strength multi-layered structure with an outer barrier layer envelope of elastomeric semi-permeable material for use as a cushioning device is provided. The outer barrier layer is bonded, at a multiplicity of sites, to substantially the entire distal surfaces of a double-walled drop-thread linked fabric wherein the filaments are comprised of a highly distorted, long chain, axially orientated crystalline molecular structure which has a low gas permeability. The bond between the barrier layer and the facing fabric is substantially increased by the presence of fibrils and texturizing. The drop threads which are likewise texturized, function as stress averaging members to maintain the composite structure in either a substantially flat or planar or contoured configuration without weldments within the select load-bearing areas. This lightweight product is capable of withstanding very substantial internal inflation pressures, under severe long-term steady state and cyclical compression and flexural fatigue conditions. The product is inflated, pressurized and sealed and maintains the internal inflatant pressure for extended periods of time, generally in excess of the useful life of the overall product, by employing the diffusion pumping phenomenon of self-inflation. The cushioning device can selectively control the rate of diffusion pumping phenomenon by varying the density relationship between the elastomeric semi-permeable material of the envelope and the essentially gas impermeable highly distorted crystalline filament material of the fabric, thus improving the long term performance and durability and reducing the cost, and eliminating some of the disadvantages of the earlier cushioning products. In a limiting case, it is possible to permanently inflate the device using readily available fluids as nitrogen or air.

Dependencies are inferred from the claim text.