Patent ID: 6797757
Filing Date: 2004-09-28
Classification: B60C,C08K

Abstract:
A process of preparing a sulfur vulcanizable rubber composition which comprises:(A) preparing a particulate pre-blend by homogeneously blending (1) particles of a sulfur vulcanized, diene-based rubber composition, together with (2) a blend of tetrathiodipropionic acid (S4) and trithiodipropionic acid (S3) in a weight ratio thereof in a range of from about 80/20 to about 30/70, and particles of carbon black; or (3) particles of a composite comprised of tetrathiodipropionic acid and trithiodipropionic acid in a weight ratio thereof in a range of from about 80 to about 30/70, and a particulate support therefor selected from at least one of carbon black, precipitated silica, starch, clay, calcium carbonate, calcium silicate and titanium dioxide having a weight ratio of said tetrathiopropionic acid and trithiopropionic acid to said particulate support in a range of from about 1/10 to about 10/1; wherein about 0.18 to about 10 parts by weight of said tetrathiopropionic acid and trithiopropionic acid are provided per 100 parts by weight of diene-based rubber contained in said sulfur vulcanizable rubber composition, and wherein said particles of sulfur vulcanized rubber composition is of a particle size of less than 420 microns; (B) mixing about one to about 40 parts by weight of said particulate pre-blend with 100 parts by weight of at least one unvulcanized hydrocarbon diene-based, sulfur vulcanizable rubber to form a rubber composition comprised of said unvulcanized rubber and said pre-blend; wherein sulfur is mixed with said particulate pre-blend prior to blending said particulate pre-blend with said unvulcanized hydrocarbon diene-based, sulfur vulcanizable rubber.