Foam Thermoplastic Vulcanizate Pellet Compositions, Methods, and Articles Related Thereto
Foam pellets comprising a thermoplastic vulcanizate (TPV) and thermo-expandable microspheres, the foam pellet having a specific gravity of 0.2 to 1.0 and the TPV being composed of an at least partially vulcanized rubber component and a thermoplastic component. The foam pellets may be subsequently processed to form various foam articles without the need to include a foaming agent during processing.
1 . A foam pellet comprising a thermoplastic vulcanizate (TPV) and thermo-expandable microspheres, the foam pellet having a specific gravity of 0.1 to 1.0 and the TPV comprising an at least partially vulcanized rubber component and a thermoplastic component.
2 . The foam pellet according to claim 1 , wherein the pellet has a specific gravity of 0.5 to 0.95.
3 . (canceled)
4 . The foam pellet according to claim 1 , wherein greater than 50% of the thermo-expandable microspheres have an un-ruptured shell.
5 . The foam pellet according to claim 1 , wherein the thermo-expandable microspheres are present in an amount of 0.5% to 10% by weight of the TPV.
6 - 8 . (canceled)
9 . The foam pellet according to claim 1 , wherein the foam pellet does not comprise a thermoplastic modifier.
10 . The foam pellet according to claim 1 , wherein at least a portion of the thermo-expandable microspheres are unexpanded.
11 . The foam pellet according to claim 1 , wherein the at least partially vulcanized rubber is selected from the group consisting of an ethylene-propylene rubber; an ethylene-alpha olefin copolymer rubber; an ethylene-propylene-diene rubber; a natural rubber; a butyl rubber; a halobutyl rubber; a halogenated rubber copolymer of p-alkystyrene and at least one isomonoolefin having 4 to 7 carbon atoms; a copolymer of isobutylene and divinyl-benzene; a rubber homopolymer of a conjugated diene having from 4 to 8 carbon atoms; a rubber copolymer having at least 50 weight percent repeat units from at least one conjugated diene having from 4 to 8 carbon atoms and a vinyl aromatic monomer having from 8 to 12 carbon atoms, or acrylonitrile monomer, or an alkyl substituted acrylonitrile monomer having from 3 to 8 carbon atoms, or an unsaturated carboxylic acid monomer, or an unsaturated anhydride of a dicarboxylic acid; and the like; and any combination thereof.
12 . The foam pellet according to claim 1 , wherein the at least partially vulcanized rubber comprises ethylene-propylene-diene rubber.
13 . The foam pellet according to claim 1 , wherein the thermoplastic component is selected from the group consisting of a polymer prepared from olefin monomers having 2 to 7 carbon atoms, a copolymer prepared from olefin monomers having 2 to 7 carbon atoms with a (meth)acrylate or a vinyl acetate, and any combination thereof.
14 . The foam pellet according to claim 1 , wherein the thermoplastic component is selected from the group consisting of polyethylene, polypropylene, and any combination thereof.
15 . A single-step method for preparation of a foam pellet according to claim 1 comprising:
introducing a rubber component to an extruder;
introducing a thermoplastic component to the extruder;
optionally, introducing at least one first additive to the extruder;
introducing a curing agent, and optionally an accelerator, into the extruder;
optionally, introducing at least one second additive to the extruder downstream of at least the curing agent;
dynamically vulcanizing the rubber component, thereby forming the at least a partially vulcanized rubber component in the presence of the thermoplastic component and curing agent, thereby forming the thermoplastic vulcanizate;
introducing the thermo-expandable microspheres to the extruder;
extruding a blend of the thermoplastic vulcanizate and thermo-expandable microspheres through a die; and
pelletizing the extruded blend, thereby forming the foam pellet.
16 . The method according to claim 15 , wherein the at least one first additive is one or more of an additive oil and a particulate filler.
17 . The method according to claim 15 , wherein the at least one second additive is an additive oil.
18 . The method according to claim 15 , wherein at least one first additive is introduced to the extruder, and the at least one first additive is introduced upstream of the curing agent.
19 . The method according to claim 15 , wherein the thermo-expandable microspheres are introduced to the extruder downstream of the curing agent.
20 . The method according to claim 15 , wherein the thermo-expandable microspheres are introduced to the extruder upstream of the curing agent.
21 . The method according to claim 15 , wherein the thermo-expandable microspheres are introduced to the extruder simultaneously with the curing agent.
22 . The method according to claim 15 , wherein the accelerator is introduced to the extruder.
23 . The method according to claim 15 , wherein the extruder is a single screw extruder or a twin screw extruder.
24 . The method according to claim 15 , wherein the thermo-expandable microspheres are dispersed in oil.
25 . The method according to claim 24 , wherein thermo-expandable microspheres dispersed in oil are introduced to the extruder by injection.
26 . The method according to claim 15 , wherein the thermo-expandable microspheres are introduced to the extruder in solid form.
27 . The method according to claim 15 , wherein the thermo-expandable microspheres are introduced to the extruder by crammer side feeder or a hopper of the extruder.
28 . The method according to claim 15 , wherein the curing agent is selected from the group consisting of a phenolic compound, a peroxide, a metal oxide, a maleimide, a sulfur-based curative, a silicon-based curative, a silane-based curative, a metal ligand complex, and any combination thereof.
29 . The method according to claim 15 , wherein the thermo-expandable microspheres are introduced prior to the dynamic vulcanization.
30 - 56 . (canceled)