Processes for the removal of rubber from non-hevea plants
Provided herein are organic solvent-based processes for the removal of rubber from non- Hevea plants such as guayule shrubs. By the use of the processes, solid purified rubber can be obtained that contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ash, and 0.1-4 weight % resin (when it has been dried so as to contain 0.8 weight % volatile matter).
1. An organic solvent-based process for the removal of rubber from guayule plant matter comprising:
a. utilizing a slurry containing (i) guayule plant matter, the guayule plant matter comprising bagasse, rubber and resin; (ii) at least one non-polar organic solvent; and (iii) at least one polar organic solvent, wherein the slurry contains 10-50% by weight plant matter, 50-90% by weight of (ii) and (iii) combined, and 0.5-10 weight % water from the plant matter, and wherein the at least one polar organic solvent and at least one non-polar organic solvent are present in relative weight amounts of 50-90% and 10-50%, respectively;
b. removing a majority of the bagasse from the slurry to produce a miscella and a first bagasse portion wherein the miscella contains 1-10 weight % rubber and 1-10 weight % resin;
c. optionally adding additional polar organic solvent, non-polar organic solvent or a combination thereof to the miscella to form a reduced viscosity miscella where any polar organic solvent and non-polar organic solvent may be the same or different than those utilized in (a) and where the amount of any additional polar organic solvent that is added is less than the amount that causes the rubber contained with the reduced viscosity miscella to coagulate;
d. utilizing a centrifuge to remove 80-95 weight % of bagasse from the miscella resulting from (b) or (c) (based on the total weight of bagasse present in the miscella) to form a purified miscella and a second bagasse fraction, wherein the purified miscella contains 0.5-7 weight % rubber and 0.5-8 weight % resin, based upon the total weight of the purified miscella;
e. optionally treating the purified miscella to remove additional bagasse thereby producing a clarified rubber solution that contains 0.01-1% by weight of bagasse wherein 90-99% of any additional bagasse that is removed has a particle size greater than 45 microns;
f. increasing the relative amount of polar organic solvent as compared to non-polar organic solvent within the clarified rubber solution or the purified miscella so as to coagulate the rubber; and
g. producing solid purified rubber from the coagulated rubber where when said solid purified rubber contains 0.8 weight % volatile matter it also contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ash and 0.1-4 weight % resin;
wherein at least (a)-(e) are conducted at a temperature or temperatures of 10-80° C. and a pressure of 35 to 1000 kPa.
2. The process of claim 1 , wherein one or more antioxidants is utilized in the slurry of (a).
3. The process of claim 1 , wherein one or more antioxidants is utilized in after (d).
4. The process of claim 1 , wherein the (i) guayule plant matter comprises chopped guayule plant matter.
5. The process of claim 1 , wherein the majority of bagasse removed from the slurry in (b) is 60-95 weight % of the bagasse contained within the slurry.
6. The process of claim 1 , wherein removing of the majority of bagasse in (b) comprises use of a screw press.
7. The process of claim 1 , wherein the plant matter in the slurry has been in contact with the solvents (ii) and (iii) for 0.3 to 3 hours prior to (b).
8. The process of claim 1 , wherein the centrifuge of (d) is a disk centrifuge operated at a speed sufficient to generate a g force of 4,000-12,000.
9. The process of claim 1 , wherein at least a portion of at least one of the first bagasse portion and the second bagasse portion is recycled into the slurry, allowing for transfer of additional rubber or resin that is associated with the bagasse portion(s) into the miscella that is produced in (b).
10. The process of claim 9 , wherein removing of the majority of bagasse in (b) comprises use of a screw press.
11. The process of claim 1 , wherein the plant matter comprises chopped guayule shrub including bark and woody tissue with no more than 5 weight % of the plant material comprising leaves.
12. The process of claim 1 , wherein at least (a)-(e) are conducted at a temperature or temperatures of 10-50° C.
13. The process of claim 4 , wherein the chopped plant matter is passed over a mesh screen having a mesh rating of 16 to 30 mesh in order to remove undersize material prior to being added to the slurry.
14. The process of claim 1 , wherein the non-polar organic solvent and any additional non-polar organic solvent comprises at least one: alkane having 6 carbon atoms, cycloalkane having 6 carbon atoms, or a combination thereof, and the polar organic solvent and any additional polar organic solvent comprises acetone.
15. The process of claim 1 , wherein the (ii) at least one non-polar organic solvent; and the (iii) at least one polar organic solvent are present in relative weight amounts of 60-85% and 15-40%, respectively.
16. The process of claim 14 , wherein the alkane having 6 carbon atoms, cycloalkane having 6 carbon atoms or a combination thereof is present in a total amount of 60-85% by weight and the acetone polar organic solvent is present in an amount of 15-40% by weight.
17. The process of claim 1 , wherein the solid purified rubber of (g) has a molecular weight of 1,000,000 to 1,500,000.
18. An organic solvent-based process for the removal of rubber from guayule plant matter comprising:
a. utilizing a slurry containing (i) guayule plant matter, the guayule plant matter comprising bagasse, rubber and resin; (ii) at least one non-polar organic solvent selected from the group consisting of alkanes having from 4 to 9 carbon atoms; cycloalkanes and alkyl cycloalkanes having from 5 to 10 carbon atoms; and combinations thereof; (iii) at least one polar organic solvent selected from the group consisting of alcohols having 1 to 8 carbon atoms; ethers and esters having from 2 to 8 carbon atoms; cyclic ethers having from 4 to 8 carbon atoms; and ketones having from 3 to 8 carbon atoms; and combinations thereof; and (iv) one or more antioxidants, wherein the slurry contains 10-50% by weight plant matter, 50-90% by weight of (ii) and (iii) combined, and 0.5-10 weight % water from the plant matter, and wherein the at least one polar organic solvent and at least one non-polar organic solvent are present in relative weight amounts of 50-90% and 10-50%, respectively;
b. utilizing a screw press to remove a majority of the bagasse from the slurry to produce a miscella and a first bagasse portion wherein the miscella contains 1-10 weight % rubber and 1-10 weight % resin;
c. optionally adding additional polar organic solvent selected from the group consisting of alcohols having 1 to 8 carbon atoms; ethers and esters having from 2 to 8 carbon atoms; cyclic ethers having from 4 to 8 carbon atoms; and ketones having from 3 to 8 carbon atoms; and combinations thereof, additional non-polar organic solvent selected from the group consisting of alkanes having from 4 to 9 carbon atoms; cycloalkanes and alkyl; cycloalkanes having from 5 to 10 carbon atoms; aromatics and alkyl substituted aromatics having from 6 to 12 carbon atoms, or a combination of additional polar organic solvent and additional non-polar organic solvent to the miscella to form a reduced viscosity miscella wherein any polar organic solvent and non-polar organic solvent may be the same or different than those utilized in (a) and where the amount of any additional polar organic solvent that is added is less than the amount that causes the rubber contained with the reduced viscosity miscella to coagulate;
d. utilizing a centrifuge to remove 80-95 weight % of bagasse from the miscella resulting from (b) or (c) (based on the total weight of bagasse present in the miscella) to form a purified miscella and a second bagasse fraction wherein the majority of the bagasse that is removed has a particle size of less than 105 microns and wherein the purified miscella contains 0.5-7 weight % rubber and 0.5-8 weight % resin, based upon the total weight of the purified miscella;
e. optionally treating the purified miscella to remove additional bagasse thereby producing a clarified rubber solution that contains 0.01-1% by weight of bagasse wherein 90-99% of any additional bagasse that is removed has a particle size greater than 45 microns;
f. increasing the relative amount of polar organic solvent as compared to non-polar organic solvent within the clarified rubber solution or the purified miscella so as to coagulate the rubber; and
g. producing solid purified rubber from the coagulated rubber wherein when said solid purified rubber contains 0.8 weight % volatile matter it also contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ash and 0.1-4 weight % resin;
wherein at least (a)-(e) are conducted at a temperature or temperatures of 10-80° C. and a pressure of 35 to 1000 kPa.
19. The process of claim 18 , wherein the solid purified rubber of (g) has a molecular weight of 1,000,000 to 1,500,000.
20. The process of claim 18 , wherein the plant matter in the slurry has been in contact with the solvents (ii) and (iii) for 0.3 to 3 hours prior to (b).
21. The process of claim 18 , wherein the centrifuge of (d) is a disk centrifuge.
22. The process of claim 18 , wherein at least a portion of at least one of the first bagasse portion and the second bagasse portion is recycled into the slurry, allowing for transfer of additional rubber or resin that is associated with the bagasse portion(s) into the miscella that is produced in (b).
23. An organic solvent-based process for the removal of rubber from Parthenium argentatum plant matter comprising:
a. utilizing a slurry containing (i) Parthenium argentatum plant matter, the Parthenium argentatum plant matter comprising bagasse, rubber and resin; (ii) at least one non-polar organic solvent selected from the group consisting of alkanes having 6 carbon atoms, cycloalkanes having 6 carbon atoms, and combinations thereof; (iii) at least one polar organic solvent selected from the group consisting of alcohols having 1 to 8 carbon atoms; ethers and esters having from 2 to 8 carbon atoms; cyclic ethers having from 4 to 8 carbon atoms; and ketones having from 3 to 8 carbon atoms; and combinations thereof; and (iv) one or more antioxidants, wherein the slurry contains 10-50% by weight plant matter, 50-90% by weight of (ii) and (iii) combined, and 0.5-10 weight % water from the plant matter, and wherein the at least one polar organic solvent and at least one non-polar organic solvent are present in relative weight amounts of 50-90% and 10-50%, respectively;
b. removing 60 to 95% by weight of the bagasse from the slurry to produce a miscella and a first bagasse portion wherein the miscella contains 1-10 weight % rubber and 1-10 weight % resin;
c. optionally adding additional polar organic solvent selected from the group consisting of alcohols having 1 to 8 carbon atoms; ethers and esters having from 2 to 8 carbon atoms; cyclic ethers having from 4 to 8 carbon atoms; and ketones having from 3 to 8 carbon atoms; and combinations thereof, additional non-polar organic solvent selected from the group consisting of alkanes having from 4 to 9 carbon atoms; cycloalkanes and alkyl; cycloalkanes having from 5 to 10 carbon atoms; aromatics and alkyl substituted aromatics having from 6 to 12 carbon atoms, or a combination of additional polar organic solvent and additional non-polar organic solvent to the miscella to form a reduced viscosity miscella wherein any polar organic solvent and non-polar organic solvent may be the same or different than those utilized in (a) and where the amount of any additional polar organic solvent that is added is less than the amount that causes the rubber contained with the reduced viscosity miscella to coagulate;
d. removing 80-95 weight % of bagasse from the miscella resulting from (b) or (c) (based on the total weight of bagasse present in the miscella) to form a purified miscella and a second bagasse fraction, wherein the purified miscella contains 0.5-7 weight % rubber and 0.5-8 weight % resin, based upon the total weight of the purified miscella;
e. optionally treating the purified miscella to remove additional bagasse thereby producing a clarified rubber solution that contains 0.01-1% by weight of bagasse wherein 90-99% of any additional bagasse that is removed has a particle size greater than 45 microns;
f. increasing the relative amount of polar organic solvent as compared to non-polar organic solvent within the clarified rubber solution or the purified miscella so as to coagulate the rubber; and
g. producing solid purified rubber from the coagulated rubber wherein when said solid purified rubber contains 0.8 weight % volatile matter it also contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ash and 0.1-4 weight % resin;
wherein at least (a)-(e) are conducted at a temperature or temperatures of 10-80° C. and a pressure of 35 to 1000 kPa.
24. The process of claim 23 , wherein (b) comprises use of a screw press.
25. The process of claim 23 , wherein (b) comprises use of a counter-current extractor.
26. The process of claim 23 , wherein (d) comprises use of a centrifuge.