Process for producing high quality natural rubber

Abstract

This invention relates to a technique for making a high quality natural rubber composition having a dirt content of less than 0.03 percent and a constant Mooney viscosity of 60 by blending up to 60 weight percent cup-lump rubber with natural rubber made by coagulating natural rubber latex This process comprises: (1) removing foreign material from the cup-lump rubber to produce cleaned cup-lump rubber; (2) reducing the particle size of the cleaned cup-lump rubber to an average particle size of less than 35 millimeters; (3) coagulating the natural rubber latex to produce latex rubber coagulum; (4) mixing the cleaned cup-lump rubber with the latex rubber coagulum to produce a blend of cup-lump rubber and latex rubber coagulum, wherein a maximum of 60 percent by weight of the cup-lump rubber is mixed into the blend; (5) reducing the particle size of the blend of cup-lump rubber and latex rubber coagulum to a maximum particle size of 3 millimeters to produce a small particle size rubber blend; (6) conveying the small particle size rubber blend in an air medium through a pneumatic transfer system; (7) mixing about 0.1 weight percent to about 0.2 weight percent of an antioxidant into the small particle size rubber blend as its being conveyed in the air medium through the pneumatic transfer system; (8) transferring the small particle size rubber blend in the air medium into a gas-cyclone; and (9) separating the air from the small particle size rubber blend to produce the high quality natural rubber composition.

Dependencies are inferred from the claim text.