Granted Patent B2

US 10,792,851 · App. 15/713,799 · Granted Oct 6, 2020

Inventors: David Dezhou Sun (Evansville, IN); Philip A. Driskill (Newburgh, IN); Rolland Strasser (Hamden, CT)

Assignee: Berry Plastics Corporation

B29C49/22B29C44/22B29C49/0005B29C49/04B65D81/3846B29K2023/12B29K2023/14B29K2105/043B29K2105/258B29K2995/0015B29K2995/0063B29L2009/00B29L2031/712

Abstract

Claims (36)

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

injecting a blowing agent into the mixture,

extruding the mixture to form a core layer,

extruding a skin layer on the core 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 polypropylene base resin is at least one a polypropylene copolymer, a polypropylene homopolymer, or mixtures thereof.

5. The method of claim 4 , wherein the at least one polypropylene base resin is about 90% to 99.9%.

6. The method of claim 5 , wherein the at least one polypropylene base resin is about 95% to 99.9%.

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

8. The method of claim 7 , wherein the at least one nucleating agent is about 0.5% to 5%.

9. The method of claim 7 , wherein the blow agent is injected into the mixture at about 0.075, 0.1, or 0.75 lbs/hr.

10. The method of claim 1 , wherein the mixture further comprises up to about 3% (w/w) of a slip agent.

11. The method of claim 10 , wherein the slip agent is about 1% to 3%.

12. The method of claim 11 , wherein the slip agent is about 2%.

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

14. The method of claim 13 , wherein the ratio of the two polypropylene base resins is 50% to 50%.

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

16. The method of claim 15 , wherein the skin layer has a density of about 0.9 g/cm 3 .

17. The method of claim 1 , further comprising the step of extruding a second skin layer on the core layer and the skin layer.

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

19. 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 resin,

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

injecting a blowing agent into the mixture,

extruding the mixture to form a core layer,

extruding a skin layer on the core layer to establish a multi-layer structure, and

using the multi-layer structure to form an insulative cellular non-aromatic container,

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

20. The method of claim 19 , wherein the using step is a molding step.

Assignments (32)