Thermoplastic vulcanizates
A process for preparing a thermoplastic vulcanizate, the process comprising: charging a reactor with an olefinic copolymer rubber, where the olefinic copolymer rubber is characterized by a multimodal molecular weight, an average branching index of greater than 0.8, includes less than 10 parts by weight oil per 100 parts by weight rubber, includes less than 1 parts by weight non-rubber particulate, per 100 parts by weight rubber, and is in the form of granules having a particle size less than 8 mm; charging the reactor, contemporaneously or sequentially with respect to the rubber, with a thermoplastic resin, an oil, and a cure system; melt mixing the rubber, the thermoplastic resin, the oil, and the cure system; and dynamically vulcanizing the rubber.
1. A method for preparing a thermoplastic vulcanizate, the method comprising:
(i) charging a reactor with an olefinic copolymer rubber, where the olefinic copolymer rubber is metallocene catalyzed and is characterized by a bimodal molecular weight distribution that includes a first fraction and a second fraction,
where the rubber has an average branching index of greater than 0.95,
where the rubber includes less than 5 parts by weight oil per 100 parts by weight rubber,
where the rubber includes less than 1 parts by weight non-rubber particulate per 100 parts by weight rubber,
where the rubber comprises 49 wt % of the first fraction;
where the first fraction is characterized by a Mooney viscosity that is greater than the Mooney viscosity of the second fraction,
where the second fraction is characterized by a Mooney viscosity (ML (1+4)@125° C.) greater than 15 and less than 50,
where the rubber comprises less than 65 wt % ethylene-derived units and less than 5 wt % diene derived units, and
where the rubber is in the form of granules having a particle size less than 8 mm;
(ii) charging the reactor, contemporaneously or sequentially with respect to the rubber, with a thermoplastic resin, an oil, and a cure system;
(iii) melt mixing the rubber, the thermoplastic resin, the oil, and the cure system; and
(iv) dynamically vulcanizing the rubber to form a thermoplastic vulcanizate, wherein the rubber within the thermoplastic vulcanizate forms dispersed particles of vulcanized rubber within a continuous phase or matrix of the thermoplastic resin.
2. The method of claim 1 , where said step of charging the reactor, contemporaneously or sequentially with respect to the rubber, with a thermoplastic resin, an oil, and a cure system also includes charging the reactor with filler.
3. The method of claim 1 , where the olefinic copolymer rubber includes less than 1 part by weight oil per 100 parts by weight rubber.
4. The method of claim 3 , where the olefinic copolymer rubber is devoid of oil.
5. The method of claim 1 , where the olefinic copolymer rubber includes less than 0.1 part by weight non-rubber particulate per 100 parts by weight rubber.
6. The method of claim 1 , where the olefinic copolymer rubber includes less than 0.01 part by weight non-rubber particulate per 100 parts by weight rubber.
7. The method of claim 1 , where the olefinic copolymer rubber is in the form of granules having a particle size of less than 6 mm.
8. The method of claim 1 , where the olefinic copolymer rubber is a terpolymer of ethylene, propylene, and 5-ethylidene-2-norbornene, and where the thermoplastic resin is a propylene-based thermoplastic.
9. The method of claim 1 , where the process is continuous.
10. A process for preparing a thermoplastic vulcanizate, the process comprising:
(i) charging a reactor with an olefinic copolymer rubber, where the olefinic copolymer rubber is synthesized by employing a metallocene catalyst and is characterized by a bimodal molecular weight distribution that includes a first fraction and a second fraction,
where the rubber has an average branching index of greater than 0.95;
where the first fraction is characterized by a Mooney viscosity that is greater than the Mooney viscosity of the second fraction,
where the second fraction is characterized by a Mooney viscosity (ML (1+4)@125° C.) greater than 15 and less than 50,
where the rubber comprises 49 wt % of the first fraction,
where the rubber comprises less than 65 wt % ethylene-derived units and less than 5 wt % diene derived units, and
where the rubber includes less than 1 part by weight oil per 100 parts by weight rubber;
(ii) charging the reactor, contemporaneously or sequentially with respect to the rubber, with a thermoplastic resin, an oil, and a cure system;
(iii) melt mixing the rubber, the thermoplastic resin, the oil, and the cure system; and
(iv) dynamically vulcanizing the rubber to form a thermoplastic vulcanizate, wherein the rubber within the thermoplastic vulcanizate forms dispersed particles of vulcanized rubber within a continuous phase or matrix of the thermoplastic resin.