초록 ▼

This invention is based upon the discovered that crosslinked core-shell particles can be used as a filler in low cost emulsion styrene-butadiene rubber (ESBR) with excellent results being attained. In fact, such core-shell particle filled ESBR exhibits performance similar to silica filled solution s

This invention is based upon the discovered that crosslinked core-shell particles can be used as a filler in low cost emulsion styrene-butadiene rubber (ESBR) with excellent results being attained. In fact, such core-shell particle filled ESBR exhibits performance similar to silica filled solution styrene-butadiene rubber (SSBR) in terms of dynamic response, Payne effect, rebound and tan δ at 0° C. and 100° C. The utilization of such crosslinked core-shell particles in rubber compounds offers the additional advantage of weight reduction since the core-shell particles are significantly less dense than carbon black or silica fillers. The use of the crosslinked core-shell polymers of this invention in rubber formulations in place of silica also offers the advantage of not needing any expensive silane coupling agents to attain required levels of polymer/filler interaction. Accordingly, no silane coupling agent is used in the rubber compounds of this invention which leads to reduced cost. Cost can be further reduced by virtue of the fact that compound mixing conditions can be substantially relaxed as compared to mixing silica containing rubber formulations. The present invention more specifically discloses A rubbery composition which is comprised of (1) an emulsion styrene-butadiene rubber, (2) carbon black, and (3) core-shell particles, wherein the core-shell particles are comprised of (a) a crosslinked elastomeric core comprised of repeat units that are derived from at least one diolefin monomer, and (b) a polymeric shell which is derived from at least one vinyl aromatic monomer.

대표청구항 ▼

What is claimed is: 1. A rubbery composition which is comprised of (1) an emulsion styrene-butadiene rubber, (2) carbon black, (3) core-shell particles, and (4) optionally, one or more additional rubbery polymers, wherein the core-shell particles are comprised of (a) a crosslinked elastomeric core

What is claimed is: 1. A rubbery composition which is comprised of (1) an emulsion styrene-butadiene rubber, (2) carbon black, (3) core-shell particles, and (4) optionally, one or more additional rubbery polymers, wherein the core-shell particles are comprised of (a) a crosslinked elastomeric core consisting essentially of repeat units that are derived from at least one diolefin monomer and at least one crosslinking monomer selected from the group consisting of divinyl benzene, diisopropenylbenzene, and 1,2-polybutadiene, wherein the crosslinked elastomeric core has a glass transition temperature which is within the range of-20° C. to 20° C., and (b) a polymeric shell which is comprised of at least 75 weight percent repeat units that are derived from a vinyl aromatic monomer, wherein the polymeric shell has a glass transition temperature which is within the range of 50° C. to 160° C., wherein the emulsion styrene-butadiene rubber represents at least 50 weight percent of the total weight of the emulsion styrene-butadiene rubber and additional rubbery polymers in the rubbery composition, wherein the core-shell particles are present at a level which is within the range of 5 to 40 parts by weight based on the total weight of the emulsion styrene-butadiene rubber and additional rubbery polymers in the rubbery composition, and wherein the weight ratio of the core to the shell is within the range of 15:1 to 8:1. 2. A rubbery composition as specified in claim 1 wherein the weight ratio of the core to the shell is within the range of 12:1 to 8:1. 3. A rubbery composition as specified in claim 1 wherein the carbon black is present at a level which is within the range of 20 to 100 parts by weight based on the total weight of the emulsion styrene-butadiene rubber and additional rubbery polymers in the rubbery composition. 4. A rubbery composition as specified in claim 3 wherein the core-shell particles are present at a level which is within the range of 15 to 35 parts by weight based on the total weight of the emulsion styrene-butadiene rubber and additional rubbery polymers in the rubbery composition. 5. A rubbery composition as specified in claim 3 wherein the core-shell particles are present at a level which is within the range of 20 to 30 parts by weight based on the total weight of the emulsion styrene-butadiene rubber and additional rubbery polymers in the rubbery composition. 6. A rubbery composition as specified in claim 1 wherein said composition is void of solution styrene-butadiene rubber. 7. A tire which is comprised of a generally toroidal-shaped carcass with an outer circumferential tread, two spaced beads, at least one ply extending from bead to bead and sidewalls extending radially from and connecting said tread to said beads, wherein said tread is adapted to be ground-contacting, and wherein said tread is comprised of the rubbery composition specified in claim 1. 8. A tire as specified in claim 7 wherein the glass transition temperature of the elastomeric core differs from the glass transition temperature of the polymeric shell by at least 30° C. 9. A rubbery composition as specified in claim 1 wherein the emulsion styrene-butadiene rubber represents at least 70 weight percent of the total weight of emulsion styrene-butadiene rubber and additional rubbery polymers. 10. A tire as specified in claim 7 wherein the emulsion styrene-butadiene rubber represents at least 70 weight percent of the total weight of emulsion styrene-butadiene rubber and additional rubbery polymers. 11. A rubbery composition as specified in claim 1 wherein said rubbery composition consists of (1) the emulsion styrene-butadiene rubber, (2) the carbon black, (3) the core-shell particles, (4) optionally, one or more additional rubbery polymers, and (5) one or more members selected from the group consisting of sulfur, accelerators, waxes, scorch inhibiting agents, processing aids, processing oils, antidegradants, zinc oxide, tackifier resins, reinforcing resins, fatty acids, and peptizers. 12. A rubber composition as specified in claim 11 wherein the emulsion styrene-butadiene rubber represents at least 70 weight percent of the total weight of emulsion styrene-butadiene rubber and additional rubbery polymers. 13. A rubbery composition as specified in claim 1 wherein the glass transition temperature of the elastomeric core differs from the glass transition temperature of the polymeric shell by at least 30° C. 14. A rubbery composition as specified in claim 1 wherein the glass transition temperature of the elastomeric core differs from the glass transition temperature of the polymeric shell by at least 50° C. 15. A rubbery composition as specified in claim 1 wherein the glass transition temperature of the elastomeric core differs from the glass transition temperature of the polymeric shell by at least 70° C. 16. A rubbery composition as specified in claim 1 wherein the shell is comprised of at least 85 weight percent repeat units that are derived from a vinyl aromatic monomer. 17. A rubbery composition as specified in claim 1 wherein the shell is comprised of at least 90 weight percent repeat units that are derived from a vinyl aromatic monomer. 18. A rubbery composition as specified in claim 1 wherein the crosslinking monomer is divinylbenzene. 19. A rubbery composition as specified in claim 18 wherein the crosslinking monomer is incorporated into the crosslinked elastomeric core at a level of up to 30%, by weight based upon the weight of the polymer.