Patent GB-983518-A (GB)
Title: Spongy elastomeric materials and methods and products used in the manufacture of thesame
Inventor: REID JAMES SIMS
IPC: C08J9/00
Filed: 1962-06-27
Abstract: A method of making a cellular elastomeric material comprises forming a solution or suspension of or a liquid mixture of reactants capable of forming elastomeric materials under conditions employed to transform the liquid mixture into final solid elastomer, mixing a plurality of hollow friable bodies which may be of clay or other material capable of producing closed cells within the elastomer, shaping the elastomer mixture as desired and soliidifying it, and subjecting the mixture to compression to crush the hollow bodies to powder, thereby producing a resilient cellular material.  In a modification the mixture is stratified whereby the hollow bodies collect as a separate layer and another layer is formed relatively free of the hollow bodies, and thereafter the elastomeric material is solidified when the stratified layer is of the desired thickness. The hollow bodies can be dispersed in a paste-like mixture or latex of the elastomer, or in a liquid polyester-polyisocyanate polyurethane or in a liquid polyvinyl chloride or copolymer of vinyl chloride and vinyl acetate.  Also specified are natural rubbers, synthetic rubbers such as rubbery copolymers of a conjugated diolefin and a copolymerizable vinyl compound, olefin/polysulphide rubbers, butyl rubbers and other olefin/butadiene copolymers, polychloroprene, silicone rubbers, elastomeric polymers and copolymers of methacrylic acid esters, amides and nitriles, fluorine-containing polymers, and elastomeric polyvinyl ethers.  The vinyl halides can be dispersed in dioctyl phthalate or sebacate, didecyl phthalate or octyl decyl phthalate.  Preferred polyurethanes are derived from polyesters, although polyalkylene ether glycols and triols are also mentioned. They can be cross-linked by additional polyisocyanate, peroxides, dimethylol urea, methylene bis (2-chloroaniline) or sulphur. Benzene and toluene are suitable solvents for some of the elastomers.  The hollow bodies are preferably of 0.01 to 1 mm. diameter and made of clay.  Glass bubbles can also be used.  The liquid mixture of elastomer and hollow bodies can be poured or extruded into a mould and is then made to solidify.  Alternatively the liquid mixture can be stratified, e.g. by gravity or centrifugal force, or a sphere-free layer of the same liquid used for admixing the spheres, can be poured on to a body of liquid into which spheres have been stirred. Solidification can be effected by heating (e.g. plastisols) or evaporation of solvent or by heating the necessary reactants. Crushing of the spheres is effected in a press or by passage of a sheet through rollers.  In examples: (1) a liquid polyurethane reaction product of poly(ethylene-propylene) adipate of M.W. 1800 and p,p1-di-isocyanato diphenylmethane and spherical hollow fused clay particles are mixed with a polyethylene glycol diethyl hexoate (plasticizer) containing methylene bis(2-chloroaniline).  The mixture is moulded at 212 DEG  F. and then pounded with a hammer.  Some spheres have floated to the surface leaving a thin layer of unfilled material at the bottom; (2) hollow clay spheres are dispersed in a plastisol of polyvinyl chloride in dioctyl phthalate containing a little epoxy resin. The mixture is then fused at 350 DEG  F. and cooled and the product is then crushed.  The thickness of the unfilled layer can be varied by controlling the time for which the mixture is left in the mould before curing is effected.  The particles may be first coated with adhesive to control the position they will take up in the final product. The cellular polyvinyl chloride can be used for shoe soles and crash pads for automobiles. The products are also useful for making heat and sound insulation, upholstery, and tubes having a cellular inner layer and a non-cellular outer layer.