Patent ID: 6458871
Filing Date: 2002-10-01
Classification: B60C,Y10T

Abstract:
A process of preparing a rubber composition comprises the steps of:(A) thermomechanically mixing in at least one preparatory mixing stage and to a temperature within a range of about 150Â° C. to about 185Â° C. and in the absence of addition of free sulfur (1) 100 parts by weight of at least one diene-based elastomer selected from conjugated diene homopolymers and copolymers and copolymers of at least one conjugated diene and aromatic vinyl compound, (2) about 30 to about 100 phr of particulate filler comprised of (a) about 4 to about 90 weight percent starch/plasticizer composite and, correspondingly, (b) about 96 to about 10 weight percent of at least one additional reinforcing filler selected from carbon black, alumina and silica-based fillers selected from at least one of precipitated silica, aluminosilicate, and modified carbon black containing silicon hydroxide on its surface; wherein said starch is comprised of amylose units and amylopectin units in a ratio of about 15/85 to about 35/65 and has a softening point according to ASTM No. D1228 in a range of about 180Â° C. to about 220Â° C. and where said starch/plasticizer composite has a softening point in a range of about 110Â° C. to about 170Â° C. according to ASTM No. D1228, and (3) about 0.05 to about 20 parts by weight, per part by weight of said starch/plasticizer composite, alumina and silica based filler, of at least one organosilane disulfide compound of the formula (I): Z-R1â€”Snâ€”R1-Zâ€ƒâ€ƒ(I) followed by: B) mixing sulfur and at least one organosilane polysulfide compound of formula (II) therewith in a subsequent mixing step to a temperature within in a range of about 100Â° C. to about 130Â° C.: Z-R1â€”Smâ€”R1â€”Zâ€ƒâ€ƒ(II) wherein, n is a number in a range of from 2 to about 6 and the average for n is within a range of from about 2 to 2.6; wherein m is a number of from 2 to about 8 and the average for m is within a range of about 3.5 to about 4.5; wherein Z is selected from the group consisting of: wherein R2 may be the same or different and is individually selected from the group consisting of alkyl group having 1 to 4 carbons and phenyl radicals; R3 may be the same or different and is individually selected from the group consisting of alkyl radicals having 1 to 4 carbon atoms, phenyl, alkoxy radicals having 1 to 8 carbon atoms and cycloalkoxy radicals with 5 to 8 carbon atoms groups; and R1 is selected from the group consisting of a substituted or unsubstituted alkyl radicals having a total of 1 to 18 carbon atoms and a substituted or unsubstituted aryl radicals having a total of 6 to 12 carbon atoms.