Methods of preparing a composite having elastomer and filler
Disclosed herein are methods of preparing composites from solid elastomer(s) and wet filler(s), as well as products, including composites, vulcanizates, and articles therefrom. The wet filler can have a liquid content of at least 15%. A resulting composite comprises the filler dispersed in the elastomer at a loading of at least 20 phr with a filler yield loss of no more than 10%, wherein the composite has a liquid content of no more than 10% by weight based on total weight of said composite.
1. A method of preparing a composite, comprising:
(a) charging a mixer having one or more rotors with at least a solid elastomer and a wet filler comprising a filler and a liquid present in an amount ranging from 15% to 65% by weight based on total weight of wet filler;
(b) in one or more mixing steps, mixing the at least the solid elastomer and the wet filler to form a mixture, and in at least one of said mixing steps conducting said mixing wherein the mixer has at least one temperature-control means that is set to a temperature, Tz, of 65° C. or higher, and removing at least a portion of the liquid from the mixture by evaporation; and
(c) discharging, from the mixer, the composite comprising the filler dispersed in the elastomer at a loading of at least 20 phr with a filler yield loss of no more than 5%, wherein the composite has a liquid content of no more than 10% by weight based on total weight of said composite.
2. The method of claim 1 , wherein the filler comprises at least one material selected from carbonaceous materials, carbon black, silica, nanocellulose, lignin, clays, nanoclays, metal oxides, metal carbonates, pyrolysis carbon, graphenes, graphene oxides, reduced graphene oxide, carbon nanotubes, single-wall carbon nanotubes, multi-wall carbon nanotubes, or combinations thereof, and coated and treated materials thereof.
3. The method of claim 1 , wherein the filler comprises at least one material selected from carbon black and silicon-treated carbon black.
4. The method of claim 1 , wherein in step (b) and optionally in step (a), the at least one temperature-control means is set to a temperature, T z , ranging from 65° C. to 110° C.
5. The method of claim 1 , wherein a resulting total specific energy for the mixing is at least 1,400 kJ/kg composite.
6. The method of claim 1 , wherein a time average release rate of the liquid per kg of the composite on a dry weight basis ranges from 0.01 to 0.14 kg/(min·kg).
7. The method of claim 1 , wherein the mixing of step (b) comprises applying an energy to at least one rotor of the mixer, E R , at an energy efficiency ranging from 20% to 80% according to the following equation:
Energy Efficiency=Heat Duty/ E R ×100%,
wherein the Heat Duty is the energy required to remove the liquid from 1 kg of composite at 100% efficiency.
8. The method of claim 1 , wherein one or more rubber chemicals are absent from the composite discharged in step (c).
9. The method of claim 1 , wherein the wet filler has a liquid present in an amount ranging from 30% to 65% by weight.
10. The method of claim 1 , wherein the solid elastomer is selected from natural rubber, functionalized natural rubber, styrene-butadiene rubber, functionalized styrene-butadiene rubber, polybutadiene rubber, functionalized polybutadiene rubber, polyisoprene rubber, ethylene-propylene rubber, isobutylene-based elastomers, polychloroprene rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide rubber, polyacrylate elastomers, fluoroelastomers, perfluoroelastomers, silicone elastomers, and blends thereof.
11. The method of claim 1 , wherein after substantially all of the wet filler has been charged to the mixer, a resulting specific energy for the mixing, E 100% Filler , is at least 1,100 kJ/kg composite.
12. The method of claim 1 , wherein the one or more rotors operate at a tip speed of at least 0.6 m/s for at least 50% of mixing time.
13. The method of claim 1 , wherein the liquid comprises water.
14. The method of claim 1 , wherein the wet filler is in the form of a powder, paste, pellet, or cake.
15. The method of claim 1 , further comprising mixing the discharged composite with at least one additional elastomer.
16. The method of claim 1 , wherein the solid elastomer is a first solid elastomer and the charging further comprises charging the mixer with at least one additional solid elastomer.
17. The method of claim 15 , wherein the discharged composite comprises natural rubber and the at least one additional elastomer is selected from polybutadiene and styrene-butadiene rubber.
18. The method of claim 16 , wherein the solid elastomer is natural rubber and the at least one additional elastomer is selected from polybutadiene and styrene-butadiene rubber.
19. The method of claim 1 , wherein one or more rubber chemicals are substantially absent from the composite discharged in step (c).
20. The method of claim 1 , wherein said mixing is performed in one mixing step.
21. The method of claim 1 , wherein said mixing is performed in two or more mixing steps.
22. The method of claim 1 , wherein the one or more mixing steps is a continuous process.
23. The method of claim 1 , wherein the one or more mixing steps is a batch process.
24. The method of claim 23 , wherein the mixer has a chamber capacity of at least 10 L.
25. The method of claim 1 , wherein the mixing is performed with at least one rotor selected from two-wing rotors, four-wing rotors, six-wing rotors, eight wing rotors, and one or more screw rotors.
26. The method of claim 1 , wherein the composite has an oil content of less than 5% by weight based on the total weight of the composite.
27. The method of claim 1 , wherein the filler comprises silica.
28. The method of claim 27 wherein the filler further comprises carbon black.
29. The method of claim 1 , wherein the charging comprises introducing dry filler into the mixer, wherein the dry filler is wetted by adding the liquid to form the wet filler in the mixer.
30. The method of claim 27 , wherein the charging comprises introducing dry filler into the mixer, wherein the dry filler is wetted by adding the liquid to form the wet filler in the mixer.