US 12,258,427 B2
Processes for increasing the molecular weight of guayule natural rubber
Robert W. White, Gilbert, AZ (US); and Michael R. Hartzell, Gold Canyon, AZ (US)
Assigned to Bridgestone Corporation, Chuo-ku (JP)
Appl. No. 17/415,609
Filed by Bridgestone Corporation, Chuo-ku (JP)
PCT Filed Dec. 19, 2019, PCT No. PCT/US2019/067461
§ 371(c)(1), (2) Date Jun. 17, 2021,
PCT Pub. No. WO2020/132236, PCT Pub. Date Jun. 25, 2020.
Claims priority of provisional application 62/783,232, filed on Dec. 21, 2018.
Prior Publication US 2022/0064339 A1, Mar. 3, 2022
Int. Cl. C08C 2/06 (2006.01); C08C 1/065 (2006.01); C08C 2/00 (2006.01); C08C 4/00 (2006.01)
CPC C08C 1/065 (2013.01) [C08C 2/00 (2013.01); C08C 2/06 (2013.01); C08C 4/00 (2013.01)] 21 Claims
 
1. A process for increasing the molecular weight of solubilized guayule natural rubber comprising
a. providing an organic solvent-guayule natural rubber solution comprising (i) guayule natural rubber having an initial Mw in grams/mole, and (ii) optionally guayule resin, wherein the organic solvent-guayule natural rubber solution of (a) includes about 5 to about 40 weight % guayule natural rubber, based upon the total weight of the organic solvent-guayule natural rubber solution; and
b. subjecting the organic solvent-guayule natural rubber solution of (a) to shear desolventizing under conditions including at least one of (i) a temperature of about 160 to about 280° F., or (ii) a pressure of about 29 inches Hg absolute to about 0.1 inches Hg absolute or about 100 kPa absolute to about 0.3 kPa absolute,
thereby producing a desolventized guayule natural rubber having 1 weight % or less organic solvent, and an Mw in grams/mole that is at least 10% higher than the initial Mw.