Foamed polypropylene composition suitable for sheets and articles

Patent metadata

Field	Value
Publication number	US-12252604-B2
Application number	US-202017785271-A
Country	US
Kind code	B2
Filing date	Dec 16, 2020
Priority date	Dec 16, 2019
Publication date	Mar 18, 2025
Grant date	Mar 18, 2025

Abstract

The present invention relates to a foamed polypropylene composition comprising (A) from 60.0 to 95.0 wt % of a linear propylene homopolymer and (B) from 5.0 to 40.0 wt % of a low density polyethylene, based on the total weight of the polypropylene composition, wherein the polypropylene composition before foaming has a melt flow rate MFR 2 of from 0.1 to 5.0 g/10 min, determined according to ISO 1133 at a load of 2.16 kg and a temperature of 230° C., and a F 30 melt strength of from 0.1 to 2.0 cN, determined according to ISO 16790:2005, a sheet comprising said foamed polypropylene composition, an article comprising said sheet, a process for producing said sheet and the use of said foamed polypropylene composition or said sheet for producing an article.

First claim

The invention claimed is:

1. A foamed polypropylene composition comprising:
(A) from 60.0 to 95.0 wt % of a linear propylene homopolymer and
(B) from 5.0 to 40.0 wt % of a low density polyethylene,
based on the total weight of the polypropylene composition,
wherein the polypropylene composition before foaming has a melt flow rate MFR 2 of from 0.1 to 5.0 g/10 min, determined according to ISO 1133 at a load of 2.16 kg and a temperature of 230° C., and a F 30 melt strength of from 0.1 to 2.0 cN, determined according to ISO 16790:2005.

2. The foamed polypropylene composition according to claim 1 having a v30 melt extensibility of less than 150 mm/s, determined according to ISO 16790:2005.

3. The foamed polypropylene composition according to claim 1 , wherein the linear propylene homopolymer (A) has a F 30 melt strength of less than 5.0 cN, and/or a v30 melt extensibility of less than 150 mm/s, both determined according to ISO 16790:2005 and/or a melt flow rate MFR 2 of from 0.5 to 6.0 g/10 min, determined according to ISO 1133 at a load of 2.16 kg and a temperature of 230° C.

4. The foamed polypropylene composition according to claim 1 , wherein the low density polyethylene (B) has a density of from 915 to 930 kg/m 3 , determined according to ISO 1183D and/or a melt flow rate MFR 2 of from 0.1 to 2.0 g/10 min, determined according to ISO 1133 at a load of 2.16 kg and a temperature of 190° C.

5. The foamed polypropylene composition according to claim 1 , wherein the polypropylene composition further comprises a nucleating agent (C).

6. The foamed polypropylene composition according to claim 1 , wherein the polypropylene composition further comprises a foaming agent (D).

7. The foamed polypropylene composition according to claim 1 , having a density after foaming of from 300 to 700 kg/m 3 .

8. The foamed polypropylene composition according to claim 1 , comprising from 65.0 to 92.5 wt % of the linear propylene homopolymer and from 7.5 to 35.0 wt % of the low density polyethylene, based on the total weight of the polypropylene composition.

9. The foamed polypropylene composition according to claim 1 , comprising from 75.0 to 87.5 wt % of the linear propylene homopolymer and from 12.5 to 25.0 wt % of the low density polyethylene, based on the total weight of the polypropylene composition.

10. A sheet comprising the foamed polypropylene composition according to claim 1 .

11. The sheet according to claim 10 being a multi-layered sheet.

12. The sheet according to claim 11 comprising a core layer (CL) sandwiched by two skin layers (SL) in adherent contact with the core layer (CL) in the configuration SL-CL-SL, wherein the core layer comprises the foam according to claim 1 .

13. The sheet according to claim 12 , wherein the skin layers comprise an unfoamed propylene polymer composition.

14. The sheet according to claim 10 having a total thickness of from 175 μm to 1400 μm.

15. The sheet according to claim 12 , wherein the core layer has a thickness of from 75 μm to 1000 μm and the skin layers each independently have a thickness of from 50 μm to 200 μm.

16. A process for producing a sheet according to claim 10 comprising the steps of:
a) preparing a polypropylene composition by blending from 60.0 to 95.0 wt % of a linear propylene homopolymer (A) and from 5.0 to 40.0 wt % of a low density polyethylene (B), based on the total weight of the polypropylene composition;
b) subjecting the polypropylene composition to a foaming process;
c) forming the foamed polypropylene composition into a foamed sheet.

17. An article comprising the foamed polypropylene composition according to claim 1 .

18. The article according to claim 17 being a container, a bottle, cup, can, canister, bowl or tray.

19. An article comprising the sheet according to claim 10 .

20. An article comprising a sheet as produced by claim 16 .

Assignees

• Abu Dhabi Polymers Co Ltd Borouge
• Borealis Ag

Inventors

• Van Houcke Daniel
• Tenorio Emelito

Classifications

• C08L2203/14

  used for foams · CPC title

• C08J2423/06

  Polyethene · CPC title

• C08J2323/12

  Polypropene · CPC title

• C08J9/0061 Primary

  characterized by the use of several polymeric components · CPC title

• B32B2439/66

  Cans, tins · CPC title