Processes for recovering rubber from natural rubber latex

1. A process for recovering rubber from an aqueous non-Hevea natural rubber latex that contains natural rubber, water, extractables, and one or more additives, and is essentially free of lignocellulosic plant material, comprising the steps of:

contacting the latex with a first treatment solution whereby at least 75% of the natural rubber coagulates and a mixture containing coagulated natural rubber, water, and extractables is formed;

collecting the coagulated natural rubber;

contacting the coagulated natural rubber with a second treatment solution comprising at least one organic polar solvent in order to preferentially solvate the extractables; and

drying the coagulated natural rubber to create a resultant natural rubber wherein the resultant natural rubber has an amount of acetone extractables of 5% by weight or less.

2. The process as claimed in claim 1 , wherein the first treatment solution comprises an organic acid or a salt thereof, a mineral acid, or a salt thereof, or a combination thereof.

3. The process as claimed in claim 1 , wherein the first treatment solution comprises at least one organic polar solvent, said first and second treatment solutions being the same or different.

4. The process as claimed in claim 1 , wherein the first treatment solution comprises an acid selected from the group consisting of acetic acid, formic acid, sulfuric acid, aqueous aluminum sulfate, aqueous calcium chloride, and mixtures thereof.

5. The process as claimed in claim 3 , wherein said at least one organic polar solvent in the first treatment solution is selected from the group consisting of alcohols having from 1 to 8 carbon atoms, ketones having from 3 to 8 carbon atoms, and combinations thereof and wherein said at least one organic polar solvent in the second treatment solution is selected from the group consisting of alcohols having from 1 to 8 carbon atoms, ketones having from 3 to 8 carbon atoms, and combinations thereof.

6. The process as claimed in claim 1 , further comprising, prior to contacting the latex with the first treatment solution, the step of adding carbon black to the latex in an amount between 0.5% and 6% by weight of the resultant dried natural rubber.

7. The process as claimed in claim 1 , further comprising, prior to contacting the coagulated natural rubber with the second treatment solution, the step of adding carbon black to the coagulated natural rubber in an amount between 0.5% and 6% by weight of the resultant dried natural rubber.

8. The process as claimed in claim 6 , wherein the first and second treatment solutions consist essentially of acetone.

9. The process as claimed in claim 7 , wherein the first and second treatment solutions consist essentially of acetone.

10. The process as claimed in claim 2 , wherein the amount of acetone extractables in the resultant natural rubber is 2% by weight or less.

11. The process as claimed in claim 3 , wherein the amount of acetone extractables in the resultant natural rubber is 2% by weight or less.

12. A process for recovering rubber from an aqueous non-Hevea natural rubber latex that contains natural rubber, water, extractables, and one or more additives, and is essentially free of lignocellulosic plant material, comprising the steps of:

contacting the latex with a first treatment solution comprising acetone whereby at least 75% of the natural rubber coagulates and a mixture containing coagulated natural rubber, water, and extractables is formed;

collecting the coagulated natural rubber;

contacting the coagulated natural rubber with a second treatment solution comprising acetone in order to preferentially solvate the extractables; and

drying the coagulated natural rubber to create a resultant natural rubber wherein the resultant natural rubber has an amount of acetone extractables of 5% by weight or less.

13. The process as claimed in claim 12 , further comprising, prior to contacting the latex with the first treatment solution, the step of adding carbon black to the latex in an amount between 0.5% and 6% by weight of the resultant dried natural rubber.

14. The process as claimed in claim 12 , further comprising, prior to contacting the coagulated natural rubber with the second treatment solution, the step of adding carbon black to the coagulated natural rubber in an amount between 0.5% and 6% by weight of the resultant dried natural rubber.

15. The process as claimed in claim 12 , wherein the amount of acetone extractables in the resultant natural rubber is 2% by weight or less.

16. The process as claimed in claim 12 , wherein the aqueous non-Hevea natural rubber latex comprises guayule rubber.

17. A process for recovering rubber from an aqueous guayule natural rubber latex that contains natural rubber, water, extractables, and one or more additives, and is essentially free of lignocellulosic plant material, comprising the steps of:

contacting the latex with a first treatment solution whereby at least 75% of the natural rubber coagulates and a mixture containing coagulated natural rubber, water, and extractables is formed;

collecting the coagulated natural rubber;

contacting the coagulated natural rubber with a second treatment solution comprising at least one organic polar solvent in order to preferentially solvate the extractables; and

drying the coagulated natural rubber to create a resultant natural rubber wherein the resultant natural rubber has an amount of acetone extractables of 5% by weight or less.

18. The process as claimed in claim 17 , wherein the first and second treatment solutions comprise acetone.

19. The process as claimed in claim 17 , wherein the first and second treatment solutions consist essentially of acetone.