Process for forming thermoplastic vulcanizates
Provided are methods for producing a thermoplastic vulcanizate. One method includes charging vulcanizable rubber to a reactor; charging a masterbatch of thermoplastic resin and a catalyst for a phenolic resin curative to the reactor; charging a phenolic resin curative to the reactor; and dynamically vulcanizing the rubber with the phenolic resin curative in the presence of the catalyst. Also provided are thermoplastic vulcanizates made by the methods of the invention.
1. A method for making a thermoplastic vulcanizate, the method comprising the steps of:
introducing rubber and first thermoplastic resin to an extruder through a first feeder;
mixing the rubber and first thermoplastic resin in the extruder to form a molten mass;
introducing a stannous chloride masterbatch including a second thermoplastic resin and stannous chloride to the molten mass;
melting the second thermoplastic resin of the masterbatch to thereby disperse the stannous chloride within the molten mass;
introducing a curative to the molten mass in the extruder to form a vulcanizable blend; and
dynamically vulcanizing the vulcanizable blend to form the thermoplastic vulcanizate.
2. The method of claim 1 , where the stannous chloride masterbatch includes ≧10 wt % and ≦70 wt % stannous chloride based on the total weight of the masterbatch.
3. The method of claim 1 , where the stannous chloride masterbatch is charged to the reactor in the form of pellets.
4. The method of claim 1 , where the second thermoplastic resin comprises polypropylene.
5. The method of claim 1 , where the stannous chloride masterbatch comprises anhydrous stannous chloride.
6. The method of claim 1 , further comprising introducing oil to the extruder prior to the introduction of the curative.
7. The method claim 1 , further comprising introducing oil to the extruder after the introduction of the curative.
8. The method of claim 1 , wherein the stannous chloride masterbatch consists of stannous chloride and polypropylene.
9. The method of claim 1 , wherein the stannous chloride masterbatch comprises stannous chloride, polypropylene, and less than 1 wt % of other material.