Improvements in or relating to cellular materials

Abstract

Abstract Cellular materials are formed by heating an aqueous syrup of a resinous condensation product to a temperature below the setting-point to transform it into a gel of a rubber-like consistency and heating the gel in a closed mould to cause generation of gas or vapour bubbles and to convert the gel to a rigid mass. Gas-or vapour-generating substances such as sodium bicarbonate, ammonium carbonate, diazoamino - benzene, xylene, carbon tetrachloride or acetone may be added to the gel before heating. If the pressure be released before the heated mass has become rigid, some open cells are formed. The aqueous syrups may be those obtained by condensation of phenol, cresol or xylol with aldehyde, e.g. formaldehyde, or urea, thiourea or aniline with formaldehyde, or of glycerine with phthalic anhydride. A liquid phenol-formaldehyde one-stage resin is heated at 50-80 DEG C. for 48 to 72 hours. The rubbery-like product is masticated on cold rollers, sheeted and cut up. Pieces of the material are placed in curing moulds or frames which are only partly filled, and heated for 15 minutes at 170 DEG C. The mould may be chilled before opening. A veneering material may be placed on the material in the mould so as to become pressed against the mould and attached to the material. Fillers, plasticisers and reinforcing agents may be added to the syrup or the rubbery mass. Alternatively, an aqueous condensation syrup may be heated in a mould to about 120 DEG C., whereby a gel is formed and expands to form a material with large cells. Specification 527,951, [Group V], is referred to.

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