Thermoplastic gel compositions and their methods of making
Methods and compositions are provided for preparation of thermoplastic gels. The compositions have a base composition including a thermoplastic gel and a softener oil and the gel has a hardness between 15 Shore 000 and 65 Shore 000. The gel may also include an additive, such as a mineral filler, an anti-tack agent, and a mixture of a mineral filler and an anti-tack agent. The softener oil may be a high molecular weight oil having a molecular weight greater than about 250 g/mol.
1. A thermoplastic gel, prepared from a thermoplastic gel composition comprising
50-80 wt % high molecular weight synthetic hydrocarbon softener oil;
5-20 wt % styrenic triblock copolymer;
3-12 wt % styrenic diblock copolymer; and
0.2-1.5 wt % hindered phenol stabilizer, wherein the gel has a hardness between 15 Shore OOO and 65 Shore OOO.
2. The thermoplastic gel of claim 1 , comprising:
a base composition consisting of a thermoplastic rubber comprising the styrenic triblock copolymer and the styrenic diblock copolymer, and the high molecular weight softener oil; and
the hindered phenol stabilizer and optionally at least one additive selected from the group consisting of a mineral filler, an anti-tack agent, a further stabilizer and mixtures thereof, wherein the base composition, hindered phenol stabilizer and the optional at least one additive define an overall composition, and wherein the gel has a hardness between 30 Shore OOO and 45 Shore OOO.
3. The gel of claim 1 , wherein the gel exhibits less than 20 wt % oil bleed out after being under compression of 1.2 atm after at least 25 days at 70° C.
4. The gel of claim 2 , wherein the at least one additive comprises a mineral filler, and wherein the mineral filler is between 0.1 wt % and 50 wt % of the overall composition.
5. The gel of claim 4 , wherein the mineral filler is selected from the group consisting of talc, calcium carbonate, clay, wollastonite, silicates, glass, and combinations thereof.
6. The gel of claim 2 , wherein the at least one additive comprises an anti-tack agent, and wherein the anti-tack agent is between 0.1 wt % and 10 wt % of the overall composition.
7. The gel of claim 6 , wherein the anti-tack agent is selected from the group consisting of a silicone, silane, siloxane, or copolymer thereof.
8. The gel of claim 2 , wherein the thermoplastic rubber comprises: (a) a base polymer having at least one functional group capable of crosslinking, (b) a functionalized extender, and (c) an optional crosslinker having multiple functional groups that are compatible and willing to react with the functional groups in the base polymer or the functionalized extender.
9. The gel of claim 1 , wherein the high molecular weight oil is a poly-alpha olefin, linear-alpha olefin, or a combination thereof.
10. The gel of claim 2 further comprising an additional additive selected from the group consisting of a flame retardant, coloring agent, adhesion promoter, dispersant, flow improver, plasticizer, toughening agent, and combinations thereof.
11. The gel of claim 2 , comprising the further stabilizer at between 0.1 wt % and 5 wt % of the overall composition.
12. A method of making the thermoplastic gel of claim 1 , comprising:
mixing a base composition consisting of a thermoplastic rubber comprising the styrenic triblock copolymer and the styrenic diblock copolymer, and the high molecular weight softener oil, with the hindered phenol stabilizer and optionally at least one additive selected from the group consisting of a mineral filler, an anti-tack agent, a further stabilizer and mixtures thereof, wherein the base composition, hindered phenol stabilizer and optional at least one additive define an overall composition, and
providing heat to form the thermoplastic gel, wherein the resultant thermoplastic gel has a hardness between 15 Shore 000 and 65 Shore 000.
13. The method of claim 12 , wherein the gel exhibits less than 20 wt %, oil bleed out after being under compression of 1.2 atm for at least 25 days at 70° C.
14. The method of claim 12 , wherein the styrenic diblock copolymer is selected from the group consisting of a styrene-ethylene/butylene and a styrene-ethylene/propylene copolymer.
15. The method of claim 14 , wherein the styrenic triblock copolymer is selected from the group consisting of a styrene-ethylene/butylene-styrene and a styrene-ethylene/propylene-styrene copolymer.
16. The method of claim 12 , wherein the at least one additive comprises a mineral filler, and wherein the mineral filler is between 0.1 wt % and 50 wt % of the overall composition.
17. The method of claim 16 , wherein the mineral filler is selected from the group consisting of talc, calcium carbonate, clay, wollastonite, silicates, glass, and combinations thereof.
18. The method of claim 12 , wherein the at least one additive comprises an anti-tack agent, and wherein the anti-tack agent is between 0.1 wt % and 10 wt % of the overall composition.
19. The method of claim 18 , wherein the anti-tack agent is selected from the group consisting of a silicone, silane, siloxane, or copolymer thereof.
20. The method of claim 13 , wherein the high molecular weight softener oil has a molecular weight greater than 250 g/mol.
21. The method of claim 20 , wherein the high molecular weight oil is a poly-alpha olefin, a linear-alpha olefin, or a combination thereof.
22. The thermoplastic gel of claim 1 , wherein the high molecular weight synthetic hydrocarbon has a molecular weight greater than 250 g/mol.
23. The thermoplastic gel of claim 22 , wherein the high molecular weight synthetic hydrocarbon has a molecular weight between 250 g/mol and 1500 g/mol.
24. The thermoplastic gel of claim 22 , wherein the high molecular weight synthetic hydrocarbon oil is a hydrogenated synthetic hydrocarbon fluid.
25. The thermoplastic gel of claim 22 , wherein the styrenic triblock copolymer is selected from the group consisting of styrene-ethylene/butylene-styrene and styrene-ethylene/propylene-styrene copolymer.
26. The thermoplastic gel of claim 22 , wherein the gel exhibits less than 10% oil bleed out after being under compression of 1.2 atm for 26 days at 70° C.
27. The thermoplastic gel of claim 22 , wherein the styrenic diblock copolymer is selected from the group consisting of styrene-ethylene/butylene and styrene-ethylene/propylene copolymer.
28. The thermoplastic gel of claim 9 , wherein the high molecular weight synthetic hydrocarbon is a poly-alpha olefin or a linear alpha-olefin.
29. The thermoplastic gel of claim 26 , wherein the gel exhibits
a Shore OOO hardness in the range of from 32 to 44;
a stress relaxation (60 s value) of from 13-28%;
a tensile strength in a range of from 0.41 to 1 MPa; and
an elongation to break (%) in a range from 1000-2300%.
30. The gel of claim 25 , wherein the styrenic triblock and diblock copolymers are selected from the group consisting of a combination of styrene-ethylene/butylene-styrene and styrene-ethylene/butylene-styrene copolymers (SEBS/SEB) and a combination of styrene-ethylene/propylene-styrene and styrene-ethylene/propylene copolymers (SEPS/SEP).