This invention relates to inflatable air bladders, such as mattresses and the like, composed of three layers fused together to form plurality of air cells on opposite surfaces of the bladder. More particularly, the invention relates to an inflatable air bladder in which the middle layer is coated on opposite sides with barrier material which inhibits heat-sealing of one outer layer onto one side of the middle layer at the same sites that the middle layer is sealed to the other outer layer.
Air mattresses consisting of individual air cells formed by sealing together two or three layers of heat-sealable polymeric material are known in the prior art. In this connection, for example, U.S. Pat. No. 2,691,179 to Kann discloses an air mattress comprising a pneumatic structure for a mattress formed by sealing together two sheets of heat-sealable material. To overcome sagging of the mattress, known as the "hammock" effect, the cells are superimposed in two layers, with the cells in one layer disposed transversely to the cells in the other layer.
U.S. Pat. No. 2,731,652 to Bishop also discloses an air mattress formed by heat-sealing together two sheets of heat-sealable material.
U.S. Pat. No. 4,483,030 to Flick, et al, discloses an air pad formed by heat-sealing two sheets of heat-sealable material to a middle layer in a selective rectangular pattern. During the fabrication of the air pad, a sealing barrier mechanism 54 is used having a plurality of parallel fingers 58 so that the middle layer will not be heat-sealed to both the outer sheets at corresponding points.
U.S. Pat. No. 4,488,929 to Ostertag also discloses the use of a barrier apparatus for fabricating air mattresses composed of two outer sheets and center layer whereby the center layer will not be fused to both outer sheets at corresponding fusion points. In this patent, laterally-spaced, comb-like elements 5' and 6' are fitted between the opposite surface of the center layer and the two outer sheets whereby the center layer is alternately sealed to the outer sheets along laterally-spaced seal lines.
It is the principal object of this invention to provide a multi-layer, inflatable air bladder construction in which the middle layer thereof is treated with a barrier material so that it will be adapted to be heat-sealed to both outer sheets of the bladder in a predetermined air cell pattern, but without corresponding points of the middle layer being sealed to both outer sheets.
It is another object of this invention to provide an improved method of fabricating an inflatable air bladder which is simpler and more economical than methods heretofore available for the same purpose.