Development of Internal-Mixer Technology for the Rubber Industry

Abstract The early rubber industry was largely based on mixing with two-roll mills. The coming of the pneumatic-tire industry associated with the rise in popularity of the automobile brought increasing production and large quantities of fine particles and poisonous vulcanization accelerators. This made necessary the introduction of internal mixers into the rubber industry by the second decade of the 20th century. This paper treats the development of internal mixer technology from its origins in the 19th century to the late 1980's, largely through critically following the patent literature. There seems to be no other critical review of the development of internal mixer technology, and this manuscript is unique. Briefly, the technology development we will describe is as follows: There were two conflicting design approaches, one based upon a single-rotor masticator devised by Thomas Hancock in the early 19th century and a second based upon two nonintermeshing counterrotating rotors which were championed by P...