Patent GB-688909-A (GB)
Title: Improvements in or relating to the manufacture of articles of resilient cellular material
IPC: B29C44/00
Filed: 1950-01-10
Abstract: An article of resilient cellular material, which may be polyvinyl chloride or rubber latex or a mixture of these two materials, is made of two mixes of such material, the two mixes having similar constituents but differing compositions, one kind producing a highly resilient material and the other a material having a higher tensile strength and density than the first.  The materials are prepared in the form of mixes, one mix being laid down and the other mix laid upon it so that after suitable treatment the two mixes bond together to produce an article having two layers, one layer being highly resilient and the other, which is intended to be an outside or wearing surface, being tough and durable.  In example, a mix that is to form a tough skin is made from 78 per cent of polyvinyl chloride, 17 per cent of an expanding agent known under the Registered Trade Mark "Vulcacel BN" (aminobenzene) and 5 per cent of tricresylphthalate (plasticizer).  Another mix that is to form the core of the article is made from the same ingredients, but in different proportions, viz. 65, 20 and 15 per cent, respectively. The first mix is introduced into a pressure vessel, e.g. a mould or die, and forms a skin at the bottom thereof.  On to the skin is poured the second mix.  A lid is put on the mould, and the filled lidded mould is put into a press between two hot plates and heated at 310 DEG  F. under a pressure of 1.25 tons per square inch for a time of the order of 14 minutes for each inch of thickness of the material within the mould.  This treatment forms gas cells in the material. The material is then removed from the mould, cooled to make it solid, and then expanded as by treatment in a hot oven or with steam.  This expanding treatment expands the gases in the cells.  A reinforcing skin may be produced on more than one side of the core, in which case the skin mix is applied to the mould at the places desired for the skin and then, before applying the core mix, a supporting material such as thin tissue paper or a thin sheet of thermoplastic material is applied to the skin mix; this supporting material, which prevents the heavier skin mix sinking into the core mix, disintegrates during manufacture of the article.  Seats, cushions, &c. may be made.  The expanding agent may be derived from a carbonate.ALSO:An article of resilient cellular material, which may be polyvinyl chloride or rubber latex or a mixture of these two materials, is made of two mixes of such material, the two mixes having similar constituents but differing compositions, one kind producing a highly resilient material and the other a material having a higher tensile strength and density than the first.  The materials are prepared in the form of mixes, one mix being laid down and the other mix laid upon it so that after suitable treatment the two mixes bond together to produce an article having two layers, one layer being highly resilient and the other, which is intended to be an outside or wearing surface, being tough and durable.  In an example, a mix that is to form a tough skin is made from 78 per cent of polyvinyl chloride, 17 per cent of an expanding agent known under the Registered Trade Mark "Vulcacel BN" (aminobenzene) and 5 per cent of tricresylphthalate (plasticizer).  Another mix that is to form the core of the article is made from the same ingredients, but in differing proportions, viz. 65, 20 and 15 per cent respectively. The first mix is introduced into a pressure vessel, e.g. a mould or die, and forms a skin at the bottom thereof.  Onto the skin is poured the second mix.  A lid is put on the mould, and the filled lidded mould is put into a press between two hot plates and heated at 310 DEG  F. under a pressure of 1.25 tons per sq. inch for a time of the order of 14 minutes for each inch of thickness of the material within the mould.  This treatment forms gas cells in the material.  The material is then removed from the mould, cooled to make it solid, and then expanded as by treatment in a hot oven or with steam.  This expanding treatment expands the gases in the cells.  A reinforcing skin may be produced on more than one side of the core, in which case the skin mix is applied to the mould at the places desired for the skin and then, before applying the core mix, a supporting material such as thin tissue paper or a thin sheet of thermoplastic material is applied to the skin mix: this supporting material, which prevents the heavier skin mix sinking into the core mix, disintegrates during manufacture of the article. Seats, cushions, &c. may be made.  The expanding agent may be derived from a carbonate.