Foam rubber is produced by foaming an aqueous polymer latex containing at least 0.05 percent by weight zinc oxide, based on the polymer, and from 0.2 to 5.0 percent by weight ammonium polyphosphate, based on the polymer; then heating the foam to solidify and dry it. The ammonium polyphosphate can be the sole gellant; or a soluble ammonium salt gellant can be used in addition. Greater "gel tolerance" results in the latter case.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of my copending application Ser. No. 42,552, filed June 1, 1970 and now abandoned, entitled PROCESS OF MAKING FOAM RUBBER, AND THE FOAM RUBBER THUS PRODUCED.
An amine-sulfamate is added to a natural rubber latex or a latex of a rubbery C.sub.4 -C.sub.10 conjugated diene polymer in which the rubbery polymer particles are maintained in a dispersed state by an emulsifier which forms water-insoluble compounds on reaction with zinc or cadmium ions to form a latex composition which is suitable for use in the preparation of latex foam rubbers and films. The composition is stable to storage at ambient temperatures for lengthy periods of time. To prepare the foam rubber, the amine-sulfamate-containing latex is compounded with (1) a material which supplies zinc or cadmium ions such as an oxide or carbonate of zinc or cadmium, (2) ammonia or a compound which releases ammonia on heating, (3) a vulcanization system for the rubbery polymer and (4) other materials such as foaming agents, sensitizing agents, antioxidants, fillers, thickeners, etc. as required and then foamed, shaped and heated to cause gelation, drying and vulcanization. A water soluble C.sub.1 -C.sub.8 alkyl or alkanol amine containing 1-5 amino groups can be substituted for part of the ammonia. By omitting the foaming step, films can be obtained.
There is provided ammonium or alkali metal salts of liquid, water-soluble higher, aliphatic fatty acid ethanolamide sulfosuccinate as foaming agents for a variety of latices and latex compositions containing the same. The foaming agents are further characterized as having the formula: ##SPC1## Where R is a higher, aliphatic fatty acid moiety, and M is an ammonium, sodium, potassium or lithium cation.
Two preformed materials such as paper, fabrics, glass, sheet metal, at least one of which is pervious to water vapor, are joined together with a solvent-free adhesive based on a latex of a rubbery polymer. The latex is one which is stabilized with an emulsifier which forms water-insoluble compounds with zinc or cadmium ions. Included in the adhesive formulation is an ammonium or amine salt gelling agent for the latex, a zinc or cadmium ion donor compound and sufficient ammonia or a compound which releases ammonia to provide a pH of above 8 to the adhesive formulation. A surface of at least one of the preformed materials is coated with the adhesive and then contacted with a surface of the other material and held in such contact while heating to gel the latex and evaporate the water from the intersurface layer of adhesive.
Aqueous polymer dispersions whose polymer is built up of a) at least 50% by weight of butadiene, isoprene or a mixture thereof, b) at least 10% by weight of an ester of (meth)acrylic acid and a C.sub.1 -C.sub.8 -alkanol and c) from 0 to 10% by weight of other comonomers, where the total amount of monomers a) and b) makes up at least 90% by weight of the total amount of monomers, are useful for producing flame-resistant latex foam rubber which contains only hydrates of inorganic salts as flame retardants.
A sponge rubber rug underlay compound which is capable of withstanding a temperature of about 275.degree.F. for at least about 24 hours without appreciable degradation, or loss of resiliency. The compound comprises about 100 parts of a rubber which may be subject to oxidative degradation, between about 200 and about 250 parts of calcium carbonate, from about 0.5 to about 3.0 parts of an antioxidant and from about 1.5 to about 3.0 parts of an alkali metal phosphate.
