Patent ID: 6273163
Filing Date: 2001-08-14
Classification: B60C,Y10T

Abstract:
A tire having a tread of a vulcanized rubber composition prepared by a process which comprises the steps of:(A) thermomechanically mixing in at least one preparatory mixing stage and to a temperature within a range of from 150.degree. C. to 185.degree. C. and in the absence of addition of free sulfur(1) 100 parts by weight of at least one diene-based elastomer selected from homopolymers and copolymers of isoprene and 1,3-butadiene and copolymers of at least one of isoprene and 1,3-butadiene with styrene(2) from 30 to 100 phr of particulate filler comprised of(a) from 4 to 90 weight percent starch/plasticizer composite and, correspondingly,(b) from 96 to 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 amylase units and amylopectin units in a ratio of from 15/85 to 35/65 and has a softening point according to ASTM No. D1228 in a range of from 180.degree. C. to 220.degree. C. and where said starch/plasticizer composite has a softening point in a range of from 110.degree. C. to 170.degree. C. according to ASTM No. D1228, and(3) from 0.05 to 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--R1--Sn--R1--Z (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 from 100.degree. C. to 130.degree. C. :Z--R1--Sm--R1--Z (II)wherein, n is a number in a range of from 2 to 6 and the average for n is within a range of from 2 to 2.6; wherein m is a number of from 2 to 8 and the average for m is within a range of from 3.5 to 4.5; wherein Z is selected from the group consisting of: ##STR2##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; and(C) sulfur vulcanizing the resulting mixed rubber composition at a temperature in a range of from 140.degree. C. to 190.degree. C. ;wherein said plasticizer is selected from at least one of poly(ethylenevinyl alcohol), cellulose acetate and diesters of dibasic organic acids having a softening point of less than 160.degree. C. and sufficiently below the softening point of the starch with which they are being combined so that the starch/plasticizer composite has a softening point in a range of from 110.degree. C. to 170.degree. C.