in plastic compositions is its use in forming a base for chewing gum. Concentrated natural latex, estimated at 1500 gallons per month, has been used for this purpose. The interest in adapting rubber and particularly latex rubber to the manufacture of chewing gum base is to be attributed to the very poor aging qualities of the gums, such as pontianak, gutta-siak and the like, which have been used in the past.
The following procedure illustrates oue method of forming a chewing gum base: normal latex is diluted with an equal amount of 10% caustic soda solution. This is agitated and allowed to cream, after which the lower layer may be discarded. The creaming operation may be repeated several times, after which the cream is removed and heated with 200 to 400% of coumarone resin. Heating is continucd until the water is removed and a uniform mass is obtained. This mass may be washed with water to remove any traces of alkali and is finally neutralized with a small amount of tartaric or citric acid. Hyrlrogenated oil, such as hydrogenated cottonseed oil, is then added to produce the required degree of softness and will amount to 100 to 200% or even more on the rubber content.
In the manufacture of chewing gum, natural latex has found its largest use as a base for "bubble" gum. Synthetic latices of the butadiene-styrene type, and particularly those with higher butadiene content, have been used in the preparation of the conventional stick or "package" gum."
Royce J. Noble, Latex in Industry, New York, 2nd ed. 1953 (1st published 1936) Schuller International, p. 693.
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