Chemically functionalized renewed rubber composition
The renewed rubber of this invention can be used in rubber formulations that are used in manufacturing a wide array of rubber products, including tires, power transmission belts, conveyor belts, hoses, and a wide array of other products. The present invention more specifically discloses a method for manufacturing an environmentally friendly, chemically functionalized, renewed rubber composition having a highly desirable combination of physical properties and which exhibits excellent processability comprising the steps of (1) blending a micronized rubber powder with a processing aid and a chemical functionalizing agent to produce a blended mixture; (2) processing the blended mixture under conditions of high shear and low temperature to produce a reacted mixture; (3) adding a stabilizer to the reacted mixture to produce the chemically functionalized renewed rubber composition.
1. A method for manufacturing a renewed rubber composition comprising the steps of (1) blending a micronized rubber powder with a processing aid and a functionalizing agent to produce a blended mixture; (2) processing the blended mixture under conditions of high shear and low temperature to produce a reacted mixture; and (3) following formation of the reacted mixture; adding a stabilizer to the reacted mixture to produce the renewed rubber.
2. The method of claim 1 wherein the processing under conditions of high shear is generated in step (2) on a 2-roll mill.
3. The method of claim 1 wherein the functionalizing agent is a compound selected from the group consisting of alkyl thiuram sulfides, aryl thiuram sulfides, hetrocylic thiuram sulfides, thiuram disulfides, thiuram polysulfides, thiuram disulfides, thiuram multisulfides, tetrabenzylthiuram disulfides, cyclohexyl sulfonamides, t-butyl sulfonamides, tetraalkylthiuram disulfides, tetramethylthiuram disulfides, tetraethylthiuram disulfides; dipentamethylthiuram monosulfides, and tetramethylthiuram disulfides.
4. The method of claim 1 wherein a guanidine compound is blended into the micronized rubber powder in step (1).
5. The method of claim 4 wherein the guanidine compound is selected from the group consisting of alkyl guanidines, aryl guanidines, and hetrocyclic guanidines.
6. The method of claim 1 wherein N,N′-diphenyl guanidine is blended into the micronized rubber powder in step (1).
7. The method of claim 1 wherein the micronized rubber powder is a recycled tire rubber.
8. The method of claim 1 wherein the micronized rubber powder is comprised of a diene rubber.
9. The method of claim 1 wherein the stabilizer is a vulcanization retarder and wherein the renewed rubber has a solubility fraction of less than 30 percent.
10. The method of claim 1 wherein the stabilizer is N-cyclohexyl (thio) phthalimide.
11. The method of claim 1 wherein the renewed rubber composition is processed into the form of a sheet, a slab, a hexahedron, a pellet or powder.
12. The method of claim 1 wherein the micronized rubber powder is comprised of styrene-butadiene rubber.
13. The method of claim 1 wherein the micronized rubber powder is comprised of a blend of high cis-1,4-polybutadiene rubber and one or more additional rubbers wherein the high cis-1,4-polybutadiene rubber has a cis-microstructure content of at least 95 percent.
14. The method of claim 1 wherein the micronized rubber powder is crosslinked to a crosslink density which is within the range of 0.05×10 −5 moles/g to 2.0×10 −5 moles/g and has a soluble fraction of less than 90 percent.
15. The method of claim 14 wherein the micronized rubber powder is crosslinked to a crosslink density which is within the range of 0.1×10 −5 moles/g to 1.8×10 −5 moles/g and has a soluble fraction of less than 30 percent.
16. The method of claim 1 wherein said method is conducted at a temperature of less than 70° C.
17. The method of claim 1 wherein the stabilizer is added at a level which is within the range of 0.25 phr to 5 phr.
18. The method of claim 1 wherein the stabilizer is added at a level which is within the range of 0.5 phr to 3 phr.
19. The method of claim 1 wherein the stabilizer is a vulcanization retarder.
20. The method of claim 1 , further comprising aging the blended mixture prior to step (2).