GB618604A - Improvements in or relating to the manufacture of froth and materials made therefrom - Google Patents

Abstract

Foamed materials such as cellular synthetic resins are obtained by making an initial unsolidified froth from a liquid and gas, passing the froth through one or more relatively restricted openings and a mass of comparatively unfrothed liquid and then hardening the resultant foam. The frothable material may be an <PICT:0618604/IV(a)/1> aqueous dispersion of a polymer of butadiene, chloroprene, isoprene and dimethyl butadiene or a copolymer thereof with vinyl chloride, vinyl acetate, vinylidene chloride, acrylic and methacrylic esters including methyl methacrylate, vinyl pyridine, styrene, nuclear mono and dichlorstyrenes; and phenol-formaldehyde, urea-formaldehyde and other aminealdehyde resins, and may contain stabilizing agents, e.g. saponin and soap, or gelling agents, e.g. sodium silicofluoride, ammonium chloride and carbon black. The frothing gas may be air, nitrogen, p carbon dioxide or sulphur dioxide. In an example the dispersion passes through pipe 108 into a housing 1a up through which a gas passes from pipe 13. Frothing occurs in chamber 4 and the froth passes through a plurality of openings 116 into a layer of relatively unfrothed latex. At the head of the housing the frothed latex passes between porous fabric belts 52 and 53 connected with electrodes 69 and 70 by means of which the froth is at least partially vulcanised. The gelled froth then passes to a tank 85 containing hot water or sodium bicarbonate solution. In a modification the froth ascends a sloping housing which may be fitted with screens to graduate the froth and is mechanically stirred at the top.