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 first 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 of at least 15% 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 at mixer temperatures controlled by at least one temperature-control means with the one or more rotors operating at a tip speed of at least 0.6 m/s for at least 50% of the mixing time, and removing at least a portion of the liquid from the mixture by evaporation;
(c) discharging, from the first mixer, the mixture comprising the filler dispersed in the elastomer at a loading of at least 20 phr, wherein the mixture has a liquid content that is reduced to an amount less than the liquid content at the beginning of step (b), and wherein the mixture has a material temperature ranging from 100° C. to 180° C.;
(d) mixing the mixture from (c) in a second mixer to obtain the composite, wherein the second mixer is operated under at least one of the following conditions:
(i) a ram pressure of 5 psi or less;
(ii) a ram raised to at least 75% of its highest level;
(iii) a ram operated in floating mode;
(iv) a ram positioned such that it does not substantially contact the mixture;
(v) the mixer is ram-less; and
(vi) a fill factor of the mixture ranges from 25% to 70%; and
(e) discharging, from the second mixer, the composite having a liquid content of less than 3% 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 the filler comprises carbon black.
5. The method of claim 1 , wherein the filler comprises silica.
6. The method of claim 1 , wherein the wet filler has a liquid present in an amount of at least 20% by weight.
7. The method of claim 1 , wherein the elastomer is selected from natural rubber, styrene-butadiene rubber, butadiene rubber, and blends thereof.
8. The method of claim 1 , wherein the wet filler has a liquid present in an amount ranging from 40% to 65% by weight.
9. The method of claim 1 , wherein the mixture has a liquid content that is reduced to an amount less than 50 wt % of the liquid content of the mixture at the beginning of step (b).
10. The method of claim 1 , wherein the mixture in (c) has a liquid content ranging from 1% to 20% by weight.
11. The method of claim 1 , wherein the mixture in (c) has a liquid content ranging from 2% to 15% by weight.
12. 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 40° C. to 110° C.
13. 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 60° C. to 110° C.
14. 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 , of 65° C. or higher.
15. 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 100° C.
16. The method of claim 1 , wherein a time period between the start of the mixing and the discharging in (c) ranges from 3 min. to 15 min.
17. The method of claim 1 , wherein a ram down time for the mixing in the first mixer ranges from 3 min. to 15 min.
18. The method of claim 1 , wherein in (vi) a fill factor of the mixture in the second mixer ranges from 25% to 60%.
19. The method of claim 1 , wherein the second mixer is ram-less.
20. 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.
21. The method of claim 1 , wherein the solid elastomer comprises natural rubber.
22. The method of claim 7 , wherein the wet filler has a liquid present in an amount ranging from 20% to 65% by weight.
23. The method of claim 1 , wherein the mixture has a material temperature ranging from 100° C. to 140° C.
24. The method of claim 1 , wherein a resulting total specific energy of the mixing in (b) ranges from 1000 to 2500 KJ/kg.
25. The method of claim 1 , wherein the wet filler is in the form of a powder, paste, pellet, or cake.
26. The method of claim 5 , further comprising charging the mixer with a coupling agent.
27. 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.
28. The method of claim 5 , 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.