Elastomer Formulations
This present invention relates to carbon nanotubes as fillers in composites with materials such as elastomers, thermosets and thermoplastics. A further feature of this invention relates to the development of a concentrate of carbon nanotubes with an elastomer wherein the concentrate can be further diluted with an elastomer and other polymers and fillers using conventional melt mixing.
1 . A mixture comprising discrete nanotubes, an elastomer and, as optional components, a dispersing agent and/or an antioxidant.
2 . The mixture according to claim 1 , wherein the elastomer is selected from the group consisting of natural rubbers, polyisobutylene, polybutadiene, styrene-butadiene rubber, ethylene propylene diene rubbers, butyl rubber, polyisoprene, nitrile rubbers, hydrogenated nitrile rubbers, polyurethanes, polyethers, halogen containing elastomers, fluoroelastomers and combinations thereof.
3 . The mixture according to claim 1 , further comprising a dispersing agent is selected from the group consisting of anionic, non-ionic or cationic surfactants, and mixtures thereof.
4 . The mixture according to claim 1 further comprising an antioxidant selected from primary and secondary antioxidants, and mixtures thereof.
5 . The mixture according to claim 1 , wherein the nanotubes have an aspect ratio of 10 or more.
6 . The mixture according to claim 1 , wherein the nanotubes are further functionalised.
7 . The mixture according to claim 6 , wherein the nanotubes comprise an oxidation level of 2.5 to 15 weight percent.
8 . A method of making a mixture containing discrete nanotubes and an elastomer comprising mixing the elastomer and the discrete nanotubes at a temperature of 20 to 200° C.
9 . The method according to claim 8 , wherein the mixing is performed in the presence of a solvent.
10 . The method according to claim 9 , comprising forming a master batch of dispersed nanotubes and at least a first elastomer and mixing said master batch with at least a second elastomer.
11 . The method according to claim 10 , wherein said master batch is formed by melt mixing said nanotubes with said first elastomer and subsequently additional elastomers, fillers, and additives are added and melt-mixed further.
12 . The method according to claim 11 , wherein the master batch is formed in the presence of a solvent and the solvent is removed before admixing further components.
13 . The method according to claim 11 , wherein the master batch is formed in the presence of a solvent and the solvent is removed after admixing further components.
14 . The method according to claim 10 further comprising curing the mixture.
15 . The mixture according to claim 3 , wherein the dispersing agent is selected from the group consisting of dodecylbenzene sulfonic acid and salts thereof, polyether or cetyltrimethyl ammonium bromide.
16 . The mixture according to claim 5 , wherein the nanotubes are further functionalized.