POLYETHYLENE COMPOSITION FOR EXTRUSION COATING

• US 20150175827A1
• Filed: 12/01/2014
• Published: 06/25/2015
• Est. Priority Date: 12/19/2013
• Status: Abandoned Application

• Current Assignee: Nova Chemicals
• Original Assignee: Nova Chemicals
• Inventors: Keshtkar, Mehdi, Li, Tieqi
• Application Number:
  US14/556,500
• Publication Number:
  US 20150175827A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B05D 1/265 Extrusion coatings
• CPC Class Codes: C08L 2205/02 containing two or more polymers of the same C08L -group
• CPC Class Codes: C08L 2207/062 HDPE
• CPC Class Codes: C08L 2207/066 LDPE (radical process)
• CPC Class Codes: C08L 23/0815 Copolymers of ethene with aliphatic 1-olefins
• CPC Class Codes: C09D 123/06 Polyethene

Abstract

A low density polyethylene (LDPE) made in a tubular reactor has improved stretch-ratio and melt strength properties after being blended with a small amount (1-25 weight percent of the blend) of a high density polyethylene (HDPE). The blends are useful as extrusion coating compositions.

Claims

1. An extrusion coating composition comprising about 95 to about 75 weight percent (based on the weight of the composition) of a high pressure low density polyethylene produced in a tubular reactor and having a melt index I₂ of from about 2 to about 10 g/10 min;

and about 25 to about 5 weight percent (based on the weight of the composition) of a high density polyethylene having a melt index I₂ of from greater than 0.1 g/10 min. to less than 1 g/10 min.;

wherein the extrusion coating composition has a density of from about 0.918 to about 0.932 g/cm³ and an entanglement density which is at least 10% higher than the entanglement density of the high pressure low density polyethylene produced in a tubular reactor;

wherein melt index is measured according to ASTM D-1238 (using a 2.16 kg weight at 190°

C.) and density is measured according to ASTM D-792.

2. The extrusion coating composition of claim 1 wherein the high pressure low density polyethylene produced in a tubular reactor has a density of from 0.914 to 0.930 g/cm³.

3. The extrusion coating composition of claim 1 wherein the high pressure low density polyethylene produced in a tubular reactor has a M_w/M_n of at least 8.0.

4. The extrusion coating composition of claim 1 wherein the high pressure low density polyethylene produced in a tubular reactor has a melt index I₂ of from greater than 3 g/10 min. to 9 g/10 min.

5. The extrusion coating composition of claim 1 wherein the high density polyethylene has a density of greater than 0.940 g/cm³ to 0.950 g/cm³.

6. The extrusion coating composition of claim 1 wherein the high density polyethylene has a melt index I₂ of from greater than 0.1 g/10 min. to 0.7 g/10 min.

7. The extrusion coating composition of claim 1 wherein the high density polyethylene has a melt index I₂ of from 0.2 to 0.5 g/10 min.

8. The extrusion coating composition of claim 1 having a polydispersity index M_w/M_n of from about 6 to about 10.

9. The extrusion coating composition of claim 1 having a density of from about 0.920 to about 0.932 g/cm³.

10. The extrusion coating composition of claim 1 wherein the high density polyethylene is made with a Ziegler-Natta catalyst or a chromium catalyst in a single reactor.

11. The extrusion coating composition of claim 1 wherein the high density polyethylene has a broad, unimodal profile when analyzed by gel permeation chromatography.

12. An extrusion coating process characterized in that said process comprises coating a substrate with a polymer blend comprising:

about 95 to about 75 weight percent, based on the weight of the blend, of a high pressure low density polyethylene produced in a tubular reactor; and

about 25 to about 5 weight percent, based on the weight of the blend, of a high density polyethylene having a melt index I₂ of less than 1 g/10 min.;

wherein the polymer blend has a density of from about 0.918 to about 0.932 g/cm³ and an entanglement density which is at least 10% higher than the entanglement density of the high pressure low density polyethylene produced in a tubular reactor;

wherein melt index is measured according to ASTM D-1238 (using a 2.16 kg weight at 190°

C.) and density is measured according to ASTM D-792.

13. The extrusion coating process of claim 12 wherein the high pressure low density polyethylene produced in a tubular reactor has a density of from 0.914 to 0.930 g/cm³.

14. The extrusion coating process of claim 12 wherein the high pressure low density polyethylene produced in a tubular reactor has a M_w/M_n of at least 8.0.

15. The extrusion coating process of claim 12 wherein the high pressure low density polyethylene produced in a tubular reactor has a melt index I₂ of from greater than 3 g/10 min. to 9 g/10 min.

16. The extrusion coating process of claim 12 wherein the high density polyethylene has a density of greater than 0.940 g/cm³ to 0.950 g/cm³.

17. The extrusion coating process of claim 12 wherein the high density polyethylene has a melt index I₂ of from greater than 0.1 g/10 min. to 0.7 g/10 min.

18. The extrusion coating process of claim 12 wherein the high density polyethylene has a melt index I₂ of from 0.2 to 0.5 g/10 min.

19. The extrusion coating process of claim 12 wherein the blend has a polydispersity index M_w/M_n of from about 6 to about 10.

20. The extrusion coating process of claim 12 wherein the blend has a density of from about 0.920 to about 0.932 g/cm³

21. The extrusion coating process of claim 12 wherein the high density polyethylene is made with a Ziegler-Natta catalyst or a chromium catalyst in a single reactor.

22. The extrusion coating process of claim 12 wherein the high density polyethylene has a broad, unimodal profile when analyzed by gel permeation chromatography.