CO2 terminated rubber for plastics

1. A process for the manufacture of a baleable carboxylate terminated polymer comprising polymenzing at least one conjugated diene in the presence of an organolithium initiator substantially to completion and terminating the polmerization by adding carbon dioxide so as to provide said carboxylate terminated polymer, wherein said carboxylate terminated polymer has a bulk viscosity of greater than 45 and a solution viscosity of less than 75 cP.

2. The process of claim 1 wherein said conjugated diene is selected from the group consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and mixtures thereof.

3. The process of claim 1 further comprising copolymerizing additional monomers including vinyl aromatic hydrocarbons and alkenes with said conjugated diene.

4. The process of claim 1 wherein said carbon dioxide is added in an amount of at least about 0.5 a molar equivalent of said organolithium initiator.

5. The process of claim 1 wherein said carbon dioxide is added in an amount greater than the amount of said organolithium initiator.

6. The process of claim 1 wherein said carboxylate terminated polymer is further added to a HIPS or SMA resin.

7. The process of claim 1 wherein a polar compound is added to said carboxylate terminated polymer.

8. The process of claim 1 wherein the polymerization is continuous.

9. The process of claim 7 wherein said polar compound is selected from maleic anhydride, tetramethyl ethylene diamine, 2-ethylhexanoic acid, and mixtures thereof.

10. The process of claim 1 wherein the carboxylate terminated polymer has a number average molecular weight of from about 100,000 to 300,000.

11. The process of claim 10 wherein the carboxylate terminated polymer has a number average molecular weight of from about 150,000 to 250,000.

12. The process of claim 1 , wherein said carboxylate terminated polymer is suitable for use as an impact modifier in HIPS and SMA resins.

13. The process of claim 3 , wherein said vinyl aromatic hydrocarbons are selected from the group consisting of are one or more of styrene, α-methylstyrene, vinyl toluene, ethyl styrene, vinyl naphthalene, vinyl ethylnapthalene, vinyl methyl naphthalene, vinyl butyl naphthalene, vinyl diphenyl, vinyl diphenylethane, 4-vinyl-4′-methyldiphenyl, and combinations thereof.

14. The process of claim 1 , wherein said organolithium initiator is a hydrocarbyl lithium.

15. The process of claim 14 , wherein said hydrocarbyl lithium is n-butyl lithium.

16. The process of claim 3 , wherein said comonomers comprise from 5% to 30% by weight of said carboxylate terminated polymer.

17. The process of claim 1 , wherein a vinyl modifier is added to increase the vinyl content of the conjugated diene units in said carboxylate terminated polymer.

18. The process of claim 17 , wherein said vinyl modifier is selected from the group consisting of hexamethylphosphoric acid triamide, N,N,N′,N′-tetramethylethylene diamine, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 1,4-diazabicyclo [2.2.2] octane, diethyl ether, triethylamine, tri-n-butylamine, tri-n-butylphosphine, p-dioxane, 1,2-dimethoxy ethane, dimethyl ether, methyl ethyl ether, ethyl propyl ether, di-n-propyl ether, di-n-octyl ether, anisole, dibenzyl ether, diphenyl ether, dimethylethylamine, bis-oxalanyl propane, tri-n-propyl amine, trimethyl amine, triethyl amine, N,N-dimethyl aniline, N-ethylpiperidine, N-methyl-N-ethyl aniline, and N-methylmorpholine and mixtures thereof.

19. The process of claim 1 , wherein a polar additive is added to decrease solution viscosity of the resulting carboxylate terminated polymer.

20. The process of claim 19 , wherein said polar additive is selected from the group consisting of maleic anhydride, tetramethyl ethylene diamine, 2-ethylhexanoic acid, acetonitrile, and mixtures thereof.