| 摘要 |
Foamed latex sponge is prepared by compounding natural and/or synthetic rubber latex with a dispersion of an inorganic substance capable of becoming agglomerated at reduced temperature, foaming the latex and cooling it to form a copious precipitate of the said substance thereby to coagulate the latex, and then vulcanizing the product. The inorganic substance is preferably silica obtained by treating sodium silicate with a cation-exchange resin. The precipitation may be improved by adding to the latex an organic polyamine, e.g. triethylene tetramine or ethylene diamine, an amino acid such as glycine, or a protein such as glue or casein which hydrolyses to form amino acids. The latex may be that of butadiene-styrene copolymer, or a mixture of natural rubber latex and butadiene-styrene copolymer or polybutadiene latex in the proportions of 90:10 to 10:90 by weight. In an example 2 to 5 parts of vulcanizing agent, 1 to 10 parts accelerator, and 5 to 50 parts of an 18 per cent aqueous dispersion of colloidal silica, and 5 to 15 parts zinc oxide, are added at about 70 DEG F. to 100 parts latex. The mix is then frothed with the addition of 1 to 5 parts froth stabilizing agent, and coagulated by reducing its temperature below 32 DEG F. The coagulated froth is then vulcanized by heating.ALSO:Foamed latex sponge is prepared by compounding natural and/or synthetic rubber latex with a dispersion of an inorganic substance capable of becoming agglomerated at reduced temperature, foaming the latex and cooling it to form a copious precipitate of the said substance thereby to coagulate the latex, and then vulcanizing the product. The inorganic substance is preferably silica obtained by treating sodium silicate with a cation exchange resin. The precipitation may be improved by adding to the latex an organic polyamine, e.g. triethylene tetramine or ethylene diamine, an amino acid such as glycine, or a protein such as glue or casein which hydrolyzes to form amino acids. The latex may be that of butadiene-styrene, or a mixture of natural rubber latex and butadiene-styrene or polybutadiene latex in the proportions of 90 : 10 to 10 : 90 by weight. In an example a mixture, in parts by weight, of natural rubber latex (60 per cent solids) 154.32, triethylene tetramine (50 per cent solution) 2, aqueous colloidal silica (18 per cent dispersion) 22,2, zinc oxide (50 per cent dispersion) 10, and vulcanizing ingredients are frothed while a latex stabilizer is added. The resulting foam is coagulated by placing in a dry ice chest, and is subsequently vulcanized in saturated steam.
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