The Direct Reinforcement of Rubber in Latex. II. Synthetic Resins Formed in Situ by the Addition to Latex of the Starting Materials of Their Resinification

Abstract

Abstract This study makes it clear that fillers ordinarily used in the rubber industry impair the properties of latex mixtures. On the other hand, certain organic fillers, in solution and in dispersion, which are susceptible to certain chemical modifications within the latex mixtures in which they have been incorporated, and with which they are compatible, have a favorable effect. Consequently, by introducing into a latex mixture which can be gelled and vulcanized a suitable quantity of formaldehyde-resorcinol resin, in particular a soluble formaldehyde-resorcinol resin, prepared in slightly alkaline pH medium under certain carefully defined conditions, it was possible : (1) for the first time to obtain reinforced articles directly from natural rubber latex, and (2) to obtain an ensemble of properties superior to those at present known in the rubber world. The reinforcement which has been found does not seem attributable to any chemical combination between rubber and resin, but rather to a specific structure of the resin-rubber mixture. The way is now open to the direct use of latex in applications which were undreamed of previously. In fact, reinforced latex, possessing extremely high qualities, must be considered a new material, and it offers to technologists in the latex industry the opportunity to explore applications to heavy industry, such as belts, pneumatic tires, hose, and mechanical articles which must have high quality. Tests have already been undertaken in this direction, and they have given promising results and are being pursued actively. We may assume that, in the not too distant future, certain articles of reinforced latex will be manufactured on an industrial scale.