CONTINUOUS ULTRASONIC DEVULCANIZATION OF VULCANIZED ELASTOMERS

摘要

This invention relates to a continuous ultrasonic method and apparatus for breaking the carbon-sulfur (C-S), sulfur-sulfur (S-S), and if desired, carbon-carbon (C-C) bonds in a vulcanized elastomer. It is well known that vulcanized elastomers having a three-dimensional chemical network, cannot flow under the effect of heat and/or pressure. This creates a huge problem in the re- cycling of used tires and other elastomeric products. Through the applicatio n of certain levels of ultrasonic amplitudes in the presence of pressure and optionally heat, the three-dimensional network of vulcanized elastomer can be broken down. As a most desirable consequence, ultrasonically treated cured rubber becomes soft, thereby enabling this material to be reprocessed and shaped in a manner similar to that employed with uncured elastomers. The apparatus relates to the ultrasonic reactor (20) (e.g. an extruder). The reactor (20) is connected to an ultrasonic die assembly (10); the die assembly (10) consists of a transducer portion (12), which includes a power converter (14) and booster (13), connected to a horn portion (15), the assembly being supported by mounting bracket (18), and being attached to the reactor (20) through an adaptor portion (19). The reactor (20) includes a barrel (22), fed through hopper (24), the screw (26) within the barrel portion bein g driven by a drive (25), energized by a motor (28) (not shown). The horn portion (15) includes a die portion (16) through which the devulcanized elastomer being extruded is forced at a pressure shown by a pressure gauge (21). The ultrasonic generator (10) of th e ultrasonic die of the invention, movably attached by mounting bracket (18) through adaptor legs (19) to a reactor (20). The react or (20) is surrounded by a heating jacket (42). Vulcan- ized material is fed into die (16) through reactor bore exit (36) of exit bo re diameter (dr) and into die inlet bore (38) of diameter (di). The vulcanized material is moved under pressure toward die exit bore (37) and leaves through die inlet bore (38).