Resin compositions for extrusion coating

• US 7,776,987 B2
• Filed: 09/03/2004
• Issued: 08/17/2010
• Est. Priority Date: 09/05/2003
• Status: Active Grant

• Current Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Original Assignee: Dow Global Technologies, Inc. (Dow, Inc.)
• Inventors: Cooper, James L., Oswald, Thomas, Weinhold, Jeffrey D., Gillespie, David T.
• Primary Examiner(s): Jagannathan; Vasu
• Assistant Examiner(s): Krylova; Irina
• Application Number:
  US10/566,937
• Publication Number:
  US 20060281866A1
• Time in Patent Office: 2,174 Days
• Field of Search: 525/240, 525/191, 526/352, 526/352.2, 264/176.1
• US Class Current: 526/352.2
• CPC Class Codes: C08J 2300/00 Characterised by the use of unspecified polymers
• CPC Class Codes: C08J 2323/06 Polyethene
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 23/08 Copolymers of ethene C08L23/16 takes precedence
• CPC Class Codes: C08L 23/0815 Copolymers of ethene with aliphatic 1-olefins
• CPC Class Codes: C08L 2666/06 Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof
• CPC Class Codes: C09D 123/06 Polyethene
• CPC Class Codes: C09D 123/08 Copolymers of ethene C09D123/16 takes precedence

Abstract

A composition is disclosed which is particularly suited for use in extrusion coating. The composition comprises a polymeric material having a rheology such that the slope S of a natural log-natural log plot of loss modulus (or G″) versus storage modulus (or G′) is greater than [0.635*(melt index)+13.2]/[(melt index)+16.6], and wherein the polymeric material has a CDF RI fraction less than 0.23 of a GPC chromatogram which has a molecular weight above 85,000 g/mol, and a CDF LS fraction of more than 0.07 at a conventional GPC molecular weight of 1,750,000 g/mol or greater. The compositions exhibit reduced neck-in when used in extrusion coating and the neck-in is independent of melt strength, thereby facilitating improved extrusion processes.

Claims

1. A composition comprising a polymeric material having a rheology such that the slope (or S) determined by linear least squares regression, of a plot of the natural kg of loss modulus (or G″

) versus natural log of storage modulus (or G′

) is greater than [0.635*(melt index)+13.2]/[(melt index)+16.6], and wherein the polymeric material has a CDF RI fraction less than 0.23 of a GPC chromatogram which has a molecular weight above 85,000 g/mol, and a CDF LS fraction of more than 0.07 at a conventional GPC molecular weight of 1,750,000 g/mol or greater;

wherein the polymeric material has a melt index greater than 10 g/10 min and comprises an LDPE having a high molecular weight highly branched component with an MWD greater than 10 and a Mw(absolute)/Mw(GPC) ratio greater than 3.0; and

where melt index is determined according to ASTM 1238 condition 190°

C/2.16 Kg.

2. The composition of claim 1 wherein the polymeric material has a melt strength less than about 5 cN.

3. The composition of claim 1 wherein the polymeric material comprises a blend of at least two polymeric materials.

4. The composition of claim 1 wherein the polymeric material comprises Linear PE.

5. The composition of claim 1 wherein the LDPE is made in an autoclave reactor with chilled ethylene feed below 35°

C. operating in single phase mode.

6. The composition of claim 1 wherein the polymeric material has a melt index greater than about 13 g/10 min.

7. The composition of claim 1 wherein the polymeric material has a melt index less than about 100 g/10 min.

8. The composition of claim 1 wherein the polymeric material has a Mark-Houwink plot where the slope is less than 0.25 in the absolute molecular weight range between 300,000 and 3,000,000 g/mol.

9. The composition of claim 1 wherein the value for S is at least 1% greater than [0.635*(melt index)+13.2]/[(melt index)+16.6].

10. The composition of claim 9 wherein the value for S is at least 2% greater than [0.635*(melt index)+13.2]/[(melt index)+16.6].

11. The composition of claim 1 wherein the polymeric material has a CDF RI fraction less than 0.21 of a GPC chromatogram which has a molecular weight above 85,000 g/mol.

12. The composition of claim 1 wherein the polymeric material has a CDF RI fraction less than 0.20 of a GPC chromatogram which has a molecular weight above 85,000 g/mol.

13. The composition of claim 1 wherein the polymer material has a CDF LS fraction greater than 0.09 of a GPC chromatogram which has a molecular weight above 1,750,000 g/mol.

14. In a process for extruding a polymeric material onto a substrate, the improvement comprising:

using a polymeric material of claim 1.

15. The process of claim 14 wherein the neck-in observed is less than 3 inches when running at a line speed of 440 ft/min.

16. The process of claim 14 wherein the neck-in observed is less than 2.5 inches when running at a line speed of 440 ft/min.

17. The process of claim 14 wherein the neck-in observed is less than 2 inches when running at a line speed of 440 ft/min.

18. The process of claim 14 wherein the draw down is at least 1500 ft/min.

19. The process of claim 14 wherein the polymeric material has a melt strength of less than 5 cN.

20. The composition of claim 1 which has been extruded into a film layer such that the extruded polymeric film layer has a rheology such that the slope (or S) determined by linear least squares regression, of a natural log-natural log plot of loss modulus (or G″

) versus storage modulus (or C′

) is greater than (0.665*(melt index)+14.2)/((melt index)+16.6).

21. The film layer of claim 20 wherein the layer has a CDF LS fraction of more than 0.09 at a conventional GPC molecular weight of 1,750,000 g/mol or greater.

22. The film layer of claim 20 in which the film layer was produced using an extrusion coating, extrusion lamination, or cast film process.

23. The composition of claim 1 comprising:

a. from about 10 to about 25 percent by weight of the composition of a high pressure low density type polyethylene resin having a melt index (I₂) less than about 2, a molecular weight distribution greater than about 10, a Mw(absolute)/Mw(GPC) ratio greater than about 3.0, and a melt strength greater than about 24.1-18.0*log10(MI); and

b. from about 90 to about 75 percent by weight of the composition, of a Linear PE having a density in the range of 0.97-0.857 g/cc and a melt index (I₂) in the range of 20-100;

wherein the MI of the composition of matter is greater than about 10 g/10 minutes.

24. The composition of claim 23 in which component a) has a melt index (I₂) less than about 1 g/10 minutes.

25. The composition of claim 23 wherein the composition has a melt strength less than about 5 cN.

26. The composition of claim 23 wherein the Mw(absolute)/Mw(GPC) ratio of component (a) is greater than 3.2.

27. The composition of claim 23 wherein the Mw(absolute)/Mw(GPC) ratio of component (a) is greater than 3.5.