Granted Patent B2

US 9,931,781 · App. 14/468,789 · Granted Apr 3, 2018

Abstract

Claims (30)

1. A method of forming an insulative cellular non-aromatic polymeric container comprising the steps of

heating a mixture of

at least 85% (w/w) of at least one polypropylene base resin,

up to about 15% (w/w) of at least one nucleating agent, and

up to about 3% (w/w) of a slip agent,

injecting a blowing agent into the mixture,

co-extruding the mixture to form a core layer with an outer skin layer and an inner skin layer to establish a multi-layer parison, and

blow molding the multi-layer parison with air to form an insulative cellular non-aromatic container,

wherein the multi-layer parison has a density of about 0.4 g/cm 3 to about 0.8 g/cm 3 .

2. The method of claim 1 , wherein the polypropylene base resin is a polypropylene copolymer.

3. The method of claim 1 , wherein the polypropylene base resin is a polypropylene homopolymer.

4. The method of claim 1 , wherein the at least one polypropylene base resin is two polypropylene base resins.

5. The method of claim 4 , wherein the ratio of the two polypropylene base resins is 50% to 50%.

6. The method of claim 1 , wherein the at least one polypropylene base resin is about 90% to 99.9%.

7. The method of claim 6 , wherein the at least one polypropylene base resin is about 95% to 99.9%.

8. The method of claim 7 , wherein the at least one polypropylene base resin is about 96%.

9. The method of claim 1 , wherein the at least one polypropylene base resin has a melt strength of at least 36 per ISO 16790.

10. The method of claim 1 , wherein the at least one nucleating agent is about 0.1% to 5%.

11. The method of claim 10 , wherein the at least one nucleating agent is about 0.5% to 5%.

12. The method of claim 1 , wherein the slip agent is about 1% to 3%.

13. The method of claim 12 , wherein the slip agent is about 2%.

14. The method of claim 1 , wherein the blow agent is injected into the mixture at about 0.075, 0.1, or 0.75 lbs/hr.

15. The method of claim 1 , wherein the physical nucleating agent is up to 2%.

16. The method of claim 15 , wherein the nucleating agent is about 0.1% to 0.5%.

17. The method of claim 1 , wherein the mixture lacks talc.

18. The method of claim 1 , wherein the inner skin layer is a solid layer.

19. The method of claim 18 , wherein the solid inner skin layer has a density of about 0.9 g/cm 3 .

20. The method of claim 1 , wherein the outer skin layer is a solid layer.

21. The method of claim 20 , wherein the solid outer skin layer has a density of about 0.9 g/cm 3 .

22. The method of claim 1 , wherein the density of the container is about 0.5 g/cm 3 to about 1 g/cm 3 .

Assignments (32)