Patent TW-424106-B (TW)
Title: Emulsion styrene-butadiene rubber compositions, styrene-butadiene rubber latex and tire treads and tires comprising the same
Inventor: COLVIN HOWARD ALLEN
IPC: C08L53/02
Filed: 1999-03-11
Granted: 2001-03-01
Abstract: An emulsion styrene-butadiene rubber composition having improved characteristics for utilization in tire tread rubber formulations which is characterized by being comprised of (I) a high molecular weight styrene-butadiene rubber having a weight average molecular weight of from 300,000 to 2,000,000 and (II) a low molecular weight styrene-butadiene rubber having a weight average molecular weight which is from  40,000 to 280,000; wherein the ratio of the high molecular weight styrene-butadiene rubber to the low molecular weight styrene-butadiene rubber is within the range of 80:20 to 25:75; wherein the bound styrene content of the high molecular weight styrene-butadiene rubber differs from the bound styrene content of the low molecular weight styrene-butadiene rubber by 5 percentage points to 50 percentage points; wherein the styrene-butadiene rubber composition is made by coagulating a blend of a latex of the high molecular weight styrene-butadiene rubber and a latex of the low molecular weight styrene-butadiene rubber; and wherein the latex of the high molecular weight styrene-butadiene rubber and the low molecular weight styrene-butadiene rubber are made by a process which comprises (1) charging water, a soap system, a free radical generator, 1,3-butadiene monomer and styrene monomer into a first polymerization zone; (2) allowing the 1,3-butadiene monomer and the styrene monomer to copolymerize in the first polymerization zone to a monomer conversion which is within the range of 15 percent to 40 percent to produce a low conversion polymerization medium; (3) charging the low conversion polymerization medium into a second polymerization zone; (4) charging an additional quantity of 1,3-butadiene monomer and an additional quantity of styrene monomer into the second polymerization zone; and (5) allowing the copolymerization to continue until a monomer conversion of 50 percent to 100 percent is attained to produce the latex of styrene-butadiene rubber. An emulsion styrene-butadiene rubber composition which is characterized by being comprised of (I) a high molecular weight styrene-butadiene rubber having a number average molecular weight which is within the range of 200,000 to 1,000,000 and (II) a low molecular weight styrene-butadiene rubber having a number average molecular weight which is within the range of 20,000 to 150,000; wherein the ratio of the high molecular weight styrene-butadiene rubber to the low molecular weight styrene-butadiene rubber is within the range of 80:20 to 25:75; wherein the bound styrene content of the high molecular weight styrene-butadiene rubber differs from the bound styrene content of the low molecular weight styrene-butadiene rubber by 5 percentage points to 50 percentage points; wherein the styrene-butadiene rubber composition is made by coagulating a blend of a latex of the high molecular weight styrene-butadiene rubber and a latex of the low molecular weight styrene-butadiene rubber; and wherein the latex of the high molecular weight styrene-butadiene rubber and the low molecular weight styrene-butadiene rubber are made by a process which comprises (1) charging water, a soap system, a free radical generator, 1,3-butadiene monomer and styrene monomer into a first polymerization zone; (2) allowing the 1,3-butadiene monomer and the styrene monomer to copolymerize in the first polymerization zone to a monomer conversion which is within the range of 15 percent to 40 percent to produce a low conversion polymerization medium; (3) charging the low conversion polymerization medium into a second polymerization zone; (4) charging an additional quantity of 1,3-butadiene monomer and an additional quantity of styrene monomer into the second polymerization zone; and (5) allowing the copolymerization to continue until a monomer conversion of 50 percent to 100 percent is attained to produce the latex of styrene-butadiene rubber. An emulsion styrene-butadiene rubber composition which is made by a process which is characterized by coagulating a latex composition which is comprised of (a) water, (b) an emulsifier, (c) a high molecular weight styrene-butadiene rubber having a weight average molecular weight of from 300,000 to 2,000,000 and (d) a low molecular weight styrene-butadiene rubber having a weight average molecular weight of from 40,000 to 280,000; wherein the ratio of the high molecular weight styrene-butadiene rubber to the low molecular weight styrene -butadiene rubber is within the range of 80:20 to 25:75; and wherein the bound styrene content of the high molecular weight styrene-butadiene rubber differs from the bound styrene content of the low molecular weight styrene-butadiene rubber by 5 percentage points to 50 percentage points. An emulsion styrene-butadiene rubber composition which is characterized by being made by a process which comprises coagulating a latex composition which is comprised of (a) water, (b) an emulsifier, (c) a high molecular weight styrene-butadiene rubber having a weight average molecular weight of from 300,000 to 2,000,000 and (d) a low molecular weight polybutadiene rubber having a weight average molecular weight of from 40,000 to 280,000; wherein the ratio of the high molecular weight styrene-butadiene rubber to the low molecular weight polybutadiene rubber is within the range of 80:20 to 25:75; and wherein the bound styrene content of the high molecular weight styrene-butadiene rubber is from 10 weight percent to 50 weight percentage. An emulsion styrene-butadiene rubber composition which is made by a process which is characterized by coagulating a latex composition which is comprised of (a) water, (b) an emulsifier, (c) a high molecular weight polybutadiene rubber having a weight average molecular weight of from 300,000 to 2,000,000 and (d) a low molecular weight styrene-butadiene rubber having a weight average molecular weight of from 40,000 to 280,000; wherein the ratio of the high molecular weight polybutadiene rubber to the low molecular weight styrene-butadiene rubber is within the range of 80:20 to 25:75; and wherein the bound styrene content of the low molecular weight styrene-butadiene rubber is from 10 weight percent to 50 weight percentage. A styrene-butadiene rubber composition which is comprised of repeat units which are derived from styrene and 1,3-butadiene, wherein the styrene-butadiene rubber composition has a number average molecular weight as determined by thermal field flow fractionation which is within the range of 50,000 to 150,000; wherein the styrene-butadiene rubber has a light scattering to refractive index ratio which is within the range of 1.8 to 3.9. A styrene-butadiene rubber composition which is comprised of repeat units which are derived from styrene and 1,3-butadiene, wherein a plot of log frequency versus storage modulus of the styrene-butadiene rubber composition crosses over a plot of log frequency versus loss modulus of the styrene-butadiene rubber composition at a frequency within the range of 0.001 radians per second to 100 radians per second when conducted at 90 DEG C to 120 DEG C using parallel plate geometry in the dynamic oscillation frequency sweep of the styrene-butadiene rubber. A styrene-butadiene rubber composition which is comprised of repeat units which are derived from styrene and 1,3-butadiene, wherein a plot of log frequency versus storage modulus of the styrene-butadiene rubber composition crosses over a plot of log frequency versus loss modulus of the styrene-butadiene rubber composition at a frequency within the range of 0.001 radians per second to 100 radians per second when conducted at 90 DEG C to 120 DEG C using parallel plate geometry in the dynamic oscillation frequency sweep of the styrene-butadiene rubber, wherein the styrene-butadiene rubber composition has a number average molecular weight as determined by thermal field flow fractionation which is within the range of 50,000 to 150,000 and wherein the styrene-butadiene rubber has a light scattering to refractive index ratio which is within the range of 1.8 to 3.9. A styrene-butadiene rubber composition which is characterized by being comprised of repeat units which are derived from styrene and 1,3-butadiene, wherein said styrene-butadiene rubber is synthesized by emulsion polymerization and wherein said styrene-butadiene rubber composition has a tan delta at 0 DEG C which is within the range of 0.13 to 0.19 and a tan delta at 60 DEG C which is within the range of 0.06 to 0.120 after being cured in a rubber blend containing 70 parts by weight of the styrene-butadiene rubber, 30 parts by weight of high cis-1,4-polybutadiene rubber, 7.5 parts by weight of highly aromatic processing oil, 70 parts by weight of N220 carbon black, 2 parts by weight of zinc oxide, 0.8 parts by weight of a paraffin wax, 3 parts by weight of a microcrystalline wax, 1.15 parts by weight of para-phenylene diamine antioxidant, 1.2 parts by weight of N-cyclohexy1-2-benzothiazole sulfenamide, 0.3 parts by weight of tetramethyl thiuram disulfide and 1.45 parts by weight of sulfur. A styrene-butadiene rubber composition which is characterized by being comprised of repeat units which are derived from styrene and 1,3-butadiene, wherein said styrene-butadiene rubber composition has a tan delta at 0 DEG C which is within the range of 0.18 to 0.40 and a tan delta at 60 DEG C which is within the range of 0.09 to 0.16 after being cured in a rubber blend containing 70 parts by weight of the styrene-butadiene rubber, 30 parts by weight of high cis-1,4-polybutadiene rubber, 7.5 parts by weight of highly aromatic processing oil, 70 parts by weight of N220 carbon black, 2 parts by weight of zinc oxide, 0.8 parts by weight of a paraffin wax, 3 parts by weight of a microcrystalline wax, 1.15 parts by weight of antioxidant, 1.2 parts by weight of N-cyclohexy1-2-benzothiazole sulfenamide, 0.3 parts by weight of tetramethyl thiuram disulfide and 1.45 parts by weight of sulfur. A styrene-butadi