Elastomer compositions and methods
First Claim
1. A multi-stage process for producing substantially unvulcanized, processable elastomer composition, comprising:
- in a non-productive early stage of the multi-stage process, substantially dispersing modified carbon black particulate filler and sulfuir crosslinking agent into sulfur crosslinkable hydrocarbon elastomer to produce a processable, substantially unvulcanized elastomer masterbatch, the sulfuir crosslinking agent comprising sulfur or sulfur donor effective to crosslink the hydrocarbon elastomer.
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Abstract
Novel methods of making elastomer compositions irclude the use of certain modifying agents and mechanical working prior to incorporation of a vulcanization system in a first or other early stage of a multi-stage process particulate filler, such as carbon black, and sulfur cross-linking agent are substantially dispersed into sulfur crosslinkable hydrocarbon elastomer. The particulate filler and sulfur crosslinking agent can be pre-mixed together as a pre-blend prior to being added to the elastomer. A substantially unvulcanized, processable elastomer is produced by the multi-stage process, involving further mechanical working of the initial masterbatch. A curative additive comprising accelerator, and optionally additional sulfur crosslinking agent, can be added and dispersed in the elastomer to produce a vulcanizable composition. In accordance with another aspect, extender oil is added to the elastomer subsequent to addition and substantial dispersion of the filler and sulfur crosslinking agent into the elastomer in the aforesaid early stage of the multi-stage process. Significant improvement in performance characteristics is achieved, especially by preferred embodiments, including good abrasion resistance and low hysteresis measured, for example, as tan delta-max at 70° C. The present invention further relates to novel unvulcanized, processable elastomer compositions comprising certain treated carbon black particulate filler and certain pre-vulcanization modifier in an amount effective to substantially increase bound rubber content in a substantially unvulcanized processable elastomer product of a non-productive thermo-mechanical working of the elastomer composition.
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Citations
43 Claims
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1. A multi-stage process for producing substantially unvulcanized, processable elastomer composition, comprising:
in a non-productive early stage of the multi-stage process, substantially dispersing modified carbon black particulate filler and sulfuir crosslinking agent into sulfur crosslinkable hydrocarbon elastomer to produce a processable, substantially unvulcanized elastomer masterbatch, the sulfuir crosslinking agent comprising sulfur or sulfur donor effective to crosslink the hydrocarbon elastomer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A multi-stage process for producing substantially unvulcanized elastomer composition, comprising:
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forming a pre-blend of particulate fillers comprising carbon black, silica or modified carbon black, and sulfur crosslinking agent selected from sulfur donors and sulfur;
in a first stage of the multi-stage process, adding and substantially dispersing the pre-blend into sulfur crosslinkable hydrocarbon elastomer by thermomechanical working, and then adding and substantially dispersing aromatic oil into the elastomer by subsequent thermomechanical working; and
then thermomechanically working the masterbatch produced in the first stage in at least one additional stage during which a curative additive comprising accelerator for the sulfur crosslinking agent is added and substantially dispersed into the masterbatch to form the elastomer composition. - View Dependent Claims (12, 13, 15, 16)
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14. A masterbatch comprising sulfur crosslinkable hydrocarbon elastomer, particulate filler, sulfur crosslinking agent and oil, the particulate filler, sulfur crosslinking agent and oil all being substantially homogeneously distributed throughout the elastomer and the masterbatch comprising substantially no coupling agent and no accelerator for the sulfur crosslinking agent.
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17. A substantially unvulcanized, processable elastomer composition comprising:
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unsaturated elastomer, treated carbon black particulate filler, and a pre-vulcanization modifier reactive as a crosslinking agent with the elastomer and present in an amount effective to substantially increase bound rubber content in a substantially unvulcanized, processable elastomer product of a non-productive thermomechanical working of the elastomer composition. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 41, 42)
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35. A sulfur-vulcanizable substantially unvulcanized, processable elastomer composition comprising:
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sulfur-vulcanizable elastomer comprising solution SBR, natural rubber, functional solution SBR, emulsion SBR, polybutadiene, polyisoprene or a mixture of any of them;
colloidal filler material containing between 0.1 wt. % and 25 wt. % silicon, comprising silicon-treated carbon black having silicon-containing regions primarily at the surface of carbon black aggregates, silicon-treated carbon black having silicon-containing regions distributed throughout carbon black aggregates or a mixture of any of them;
pre-vulcanization modifier in an amount of 2-6 phr, comprising tertiary butylphenol polysulfide, dithiodimorpholine, dicaprolactarn disulfide or a mixture of any of them, effective to substantially increase bound rubber content in a unvulcanized masterbatch composition produced by a non-productive thermomechanical working of the masterbatch reaching a maximum temperature between 130° and
180°
C. for a suitable period of time between 10 seconds and 20 minutes in duration; and
treating agent in an amount of 1 to 4 phr bis(3-triethoxysilylpropyl)tetrasulfane, 3-thiocyanatopropyl-triethoxy silane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, vinyl-tris-(2-methoxysilane) or a mixture of any of them.
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36. An elastomer composition comprising treated carbon black particulate filler dispersed in SBR elastomer with the reaction product of pre-vulcanization modifier selected from non-silane polysulfidic organo-compounds.
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37. A sulfur-vulcanizable elastomer composition comprising colloidal filler material containing between 0.1 wt. % and 25 wt. % silicon, selected from silicon-treated carbon black having silicon-containing regions primarily at the surface of carbon black aggregates, silicon-treated carbon black having silicon-containing regions distributed throughout carbon black aggregates or any mixture thereof, dispersed in sulfur-vulcanizable elastomer selected from solution SBR, natural rubber, functional solution SBR, emulsion SBR, polybutadiene, polyisoprene or a mixture of any of them, with the reaction products (i) of a pre-vulcanization modifier selected from tertiary butylphenol polysulfide, dithiodimorpholine, dicaprolactam disulfide or i mixture of any of them, and (ii) of a second treating agent selected from bis(3-triethoxysilylpropyl)tetrasulfane, 3-thiocyanatopropyl-triethoxy silane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, vinyl-tris-(2-methonysilane) or a mixture of any of them.
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38. A sulfur-vulcanizable elastomer composition formed by a process comprising the steps of:
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(A) preparing a substantially unvulcanized, processable masterbatch comprising unsaturated elastomer, treated carbon black particulate filler and a pre-vulcanization modifier selected from non-silane polysulfidic organo-compounds effective to substantially increase bound rubber content in a unvulcanized masterbatch composition resulting from step (B); and
(B) substantially increasing bound rubber content by thermomechanically working the masterbatch of step (A) in the absence of a vulcanization system, including at least one thermal working stage reaching a maximum temperature which would be sufficient to vulcanize the base composition in the presence of a vulcanization system.
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39. A sulfur-vulcanizable elastomer composition formed by a process comprising the steps of:
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(A) preparing a masterbatch comprising colloidal filler material containing between 0.1 wt. % and 25 wt. % silicon, selected from silicon-treated carbon black having silicon-containing regions primarily at the surface of carbon black aggregates, silicon-treated carbon black having silicon-containing regions distributed throughout carbon black aggregates and any mixture thereof, dispersed in sulfur-vulcanizable elastomer selected from solution SBR, natural rubber, functional solution SBR, emulsion SBR, polybutadiene, polyisoprene and mixtures of any of them, with the reaction products (i) of a pre-vulcanization modifier selected from tertiary butylphenol polysulfide, dithiodimorpholine, dicaprolactam disulfide and mixtures of any of them, and (ii) of a second treating agent selected from bis(3-triethoxysilylpropyl)tetrasulfane, 3-thiocyanatopropyl-triethoxy silane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, vinyl-tris-(2-methoxysilane) and mixtures of any of them; and
(B) thermomechanically working the masterbatch of step (A) in the absence of a vulcanization system, including at least one thermal working stage reaching a maximum temperature between 130° and
180°
C. for a suitable period of time between 10 seconds and 20 minutes in duration.
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40. A vulcanizable elastomer composition formed by a process comprising the steps of:
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(A) preparing a masterbatch comprising unsaturated elastomer, silicon-treated carbon black particulate filler and a pre-vulcanization modifier selected from non-silane polysulfidic organo-compounds effective to substantially increase bound rubber content in the masterbatch in step (B); and
(B) thermomechanically working the masterbatch of step (A) in the absence of a vulcanization system, including at least one thermal working stage reaching a maximum temperature which would be sufficient to vulcanize the base composition in the presence of a vulcanization system; and
(C) performing a finishing step comprising adding to the masterbatch a vulcanization system effective to vulcanize the masterbatch at a vulcanization temperature, and thermomechanically working the rubber masterbatch and vulcanization system at a temperature below the vulcanization temperature.
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43. A process for making an elastomer composition comprising the steps of:
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(A) preparing a masterbatch comprising unsaturated elastomer, treated carbon black particulate filler and a pre-vulcanization modifer selected from non-silane polysulfidic organo-compounds effective to substantially increase bound rubber content in step (B); and
(B) thermomechanically working the masterbatch cf step (A) in the absence of a vulcanization system to substantially increase its bound rubber content, including at least one thermal working stage reaching a maximum temperature which would be sufficient to vulcanize the base composition in the presence of a vulcanization system.
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Specification