IP Library › Granted Patent US 6,933,344
Granted Patent B2
US 6,933,344 · App. 10/245,792 · Granted Aug 23, 2005

Thermoplastic elastomeric compositions and methods of preparing thermoplastic elastomeric compositions

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Quick Facts
Patent No.
US 6,933,344
App. No.
10/245,792
Granted
Aug 23, 2005
Kind
B2
Abstract

Thermoplastic elastomeric compositions and processes for preparing the compositions comprising a blend of polypropylene, styrene-ethylene butylene-styrene copolymer, ethylene-propylene-diene monomer elastomer, linear low density polyethylene, peroxide crosslinking agent and a crosslinking coagent. The peroxide crosslinking agent and crosslinking coagent provide a crosslinking system. The compositions improve melt strength and increase resistance to flow and tear. The composition may further comprise mineral oil, antioxidant, colorant, a processing aid and stabilizer and mixtures thereof. The processes for preparing thermoplastic elastomeric compositions are particularly useful in microcellular injection molding to form articles with improved surface characteristics.

Claims (48)

1. A composition comprising, based on the weight of the total composition:

a polymer blend comprising about 5 to about 50 wt. % polypropylene or copolymer thereof, about 5 to about 40 wt. % styrene-ethylene butylene-styrene block copolymer, about 5 to about 40 wt. % ethylene-propylene-diene monomer elastomer, and about 2 to about 5 wt. % linear low density polyethylene;

about 1 to about 12 wt. % peroxide crosslinking agent; and

about 1 to about 8 wt. % crosslinking coagent.

2. The composition of claim 1 , further comprising about 25 to about 40 wt. % of the polypropylene.

3. The composition of claim 1 , comprising about 15 to about 30 wt. % of the styrene-ethylene butylene-styrene block copolymer.

4. The composition of claim 1 , comprising about 15 to about 30 wt. % of the ethylene-propylene-diene monomer elastomer.

5. The composition of claim 1 , further comprising up to 40 wt. % mineral oil.

6. The composition of claim 1 , further comprising up to 3 wt. % antioxidant.

7. The composition of claim 1 , further comprising up to 3 wt. % colorant.

8. The composition of claim 1 , further comprising up to 3 wt. % processing aid.

9. The composition of claim 1 , further comprising up to 3 wt. % stabilizer.

10. The composition of claim 1 , wherein the peroxide crosslinking agent is dicumyl peroxide.

11. The composition of claim 1 , wherein the crosslinking coagent is trimethylolpropane trimethacrylate.

12. The composition of claim 1 , wherein the crosslinking coagent is triallyl cyanurate.

13. The composition of claim 1 , wherein the crosslinking coagent is triallyl isocyanurate.

14. The composition of claim 1 , wherein the crosslinking coagent is m-phenylene dimaleimide.

15. An article of manufacture made from the composition of claim 1 .

16. An article of manufacture made from the composition of claim 1 , wherein the article of manufacture is selected from the group consisting of sheathing, instrument panel skins, air bag covers, roof liners, seat covers and door panels.

17. A process for preparing a composition comprising, based on the total weight of the composition:

mixing about 5 to about 50 wt. % polypropylene or copolymer thereof, about 5 to about 40 wt. % styrene-ethylene butylene-styrene block copolymer, about 5 to about 40 wt. % ethylene-propylene-diene monomer elastomer, and about 2 to about 5 wt. % linear low density polyethylene to form a polymer blend; and

adding about 1 to about 12 wt. % of a peroxide crosslinking agent and about 1 to about 8 wt. % of a crosslinking coagent to said polymer blend to form a composition.

18. The composition of claim 17 , wherein the step of mixing comprises mixing about 25 to about 40 wt. % of the polypropylene or copolymer thereof, about 15 to about 30 wt. % of the styrene-ethylene butylene-styrene block copolymer, about 15 to about 30 wt. % of the ethylene-propylene-diene monomer elastomer, and about 2 to about 5 wt. % of the linear low density polyethylene to form a polymer blend.

19. The process of claim 17 , further comprising:

mixing at least one of the group consisting of up to about 40 wt. % mineral oil, up to about 3 wt. % antioxidant, up to about 3 wt. % colorant, up to about 3 wt. % processing aid, up to about 3 wt. % stabilizer, based on the total weight of the composition, and mixtures thereof, to said polymer blend.

20. The process of claim 17 , comprising:

disposing the composition into an extruder;

extruding said composition; and

processing said composition to form pellets of the composition.

21. The process of claim 17 , comprising:

disposing the polymer blend into an extruder; and

adding about 1 to about 12% of a peroxide crosslinking agent and about 1 to about 8% of a crosslinking coagent to said polymer blend downstream into said extruder to form a composition; and

processing said composition to form pellets of the composition.

22. A microcellular foaming injection molding process for producing an article of manufacture comprising:

mixing about 5 to about 50 wt. % polypropylene or copolymer thereof, about 5 to about 40 wt. % styrene-ethylene butylene-styrene block copolymer, about 5 to about 40 wt. % ethylene-propylene-diene monomer elastomer, and about 2 to about 5 wt. % linear low density polyethylene to form a polymer blend;

adding about 1 to about 12 wt. % of a peroxide crosslinking agent and about 1 to about 8 wt. % of a crosslinking coagent to said polymer blend to form a composition;

disposing said composition into an injection molding device to form a polymer melt;

disposing the polymer melt into a barrel;

adding a super critical fluid to the polymer melt within the barrel;

disposing the polymer melt with super critical fluid into a mold; and

forming an article of manufacture.

23. The process of claim 22 , wherein the step of mixing comprises mixing about 25 to about 40 wt. % of the polypropylene or copolymer thereof, about 15 to about 30 wt. % of the styrene-ethylene butylene-styrene block copolymer, about 15 to about 30 wt. % of the ethylene-propylene-diene monomer elastomer, and about 2 to about 5 wt. % of the linear low density polyethylene to form a polymer blend.

24. The process of claim 22 , comprising:

mixing at least one of the group consisting of up to about 40 wt. % mineral oil based on the total weight of the polymer blend, up to about 3 wt. % antioxidant, up to about 3 wt. % colorant, up to about 3 wt. % processing aid, up to about 3 wt. % stabilizer and mixtures thereof, based on the total weight of the composition, to said polymer blend.

25. The process of claim 22 , comprising:

disposing the composition into an extruder;

processing said composition to form pellets of the composition;

disposing said pellets of the composition into said injection molding device to form a polymer melt.