Extrusion coating composition

Abstract

Disclosed are polymer blends composed of from 25 to 75 wt % of ethylene homopolymer produced in a high pressure tubular reactor and from 75 to 25 wt % of ethylene homopolymer produced in a high pressure autoclave reactor, provided that each homopolymer is removed from the reaction zone prior to being blended together. The blends so formed have a good combination of neck-in and adhesion properties. A process for the extrusion coating of a substrate with these new polymer blends is also described.

Description

Claims

1. A polymer blend comprising: 75-25 wt % of an ethylene homopolymer produced in a tubular reactor and25-75 wt % of an ethylene homopolymer produced in a stirred autoclave reactor;provided thatthe ethylene homopolymer produced in each reactor is removed from the reaction zone prior to being blending together.

2. A polymer blend according to claim 1, wherein the ethylene homopolymer produced in a tubular reactor has a melt index, I2 of 4-10 g/10 min and the ethylene homopolymer produced in a stirred autoclave reactor has of a melt index, I2 of from 3-9 g/10 min.

3. A polymer blend according to claim 2, wherein the ethylene homopolymer produced in a tubular reactor and the ethylene homopolymer produced in the autoclave reactor have densities of from 0.914 to 0.93 g/cc.

4. A polymer blend according to claim 3, wherein the ethylene homopolymer produced in a tubular reactor has a polydispersity, Mw/Mn of 8 or more and the ethylene homopolymer produced in a stirred autoclave reactor has a polydispersity, Mw/Mn of at least 10.

5. A polymer blend according to claim 4 which has a neck-in value of 2.0-5.0 cm at a line speed of 150 ft/min.

6. A polymer blend according to claim 5, wherein the ethylene homopolymer produced in a tubular reactor contains 0-500 ppm of an antioxidant.

7. A polymer blend according to claim 6, which has a melt index, I2 of 4-10.

8. A polymer blend according to claim 7, which has a polydispersity, Mw/Mn of 10 or more.

9. An extrusion coating process characterized in that said process comprises coating a substrate with a polymer blend comprising: 75-25 wt % of an ethylene homopolymer produced in a tubular reactor and25-75 wt % of an ethylene homopolymer produced in a stirred autoclave reactor;provided that,the ethylene homopolymer produced in each reactor is removed from the reaction zone prior to being blending together.

10. An extrusion coating process according to claim 9, wherein the ethylene homopolymer produced in a tubular reactor, has a density of 0.914-0.930 g/cc and the ethylene homopolymer produced in a stirred autoclave reactor has a density of 0.914-0.930 g/cc.

11. An extrusion coating process according to claim 10, wherein the ethylene homopolymer produced in a tubular reactor has a melt index, I2 of 4-10 g/10 min and the ethylene homopolymer, produced in a stirred autoclave reactor has a melt index, I2 of 3-9 g/10 min.

12. An extrusion coating process according to claim 11, wherein the ethylene homopolymer produced in a tubular reactor contains 0-500 ppm of an antioxidant.

13. An extrusion coating process according to claim 12, wherein the ethylene homopolymer produced in a tubular reactor has a polydispersity, Mw/Mn of 8 or more, and the ethylene homopolymer produced in a stirred autoclave reactor has a polydispersity, Mw/Mn of at least 10.

14. An extrusion coating process according to claim 13, wherein the polymer blend has a neck-in value of 2.0-5.0 cm at a line speed of 150 ft/min.

15. An extrusion coating process according to claim 14, wherein the polymer blend has a melt index of 4-10 g/10 min.

16. An extrusion coating process according to claim 15, wherein the polymer blend has a polydispersity, Mw/Mn of 10 or more.

17. A polymer blend comprising: 70-40 wt % of an ethylene homopolymer, which is produced in a tubular reactor, and which has a melt index, I2 of from 4 to 10 g/10 min and which contains 0-500 ppm of an antioxidant and30-60 wt % of an ethylene homopolymer, which is produced in a stirred autoclave reactor, and which has a melt index, I2 of from 3-9 g/10 min;provided that,the ethylene homopolymer produced in each reactor is removed from the reaction zone prior to being blending together.

18. An extrusion coating process characterized in that said process comprises coating a substrate with a polymer blend comprising: 70-40 wt % of an ethylene homopolymer, which is produced in a tubular reactor, and which has a melt index, I2 of from 4-10 g/10 min and which contains 0-500 ppm of an antioxidant and30-60 wt % of an ethylene homopolymer, which is produced in a stirred autoclave reactor, and which has a melt index, I2 of from 3-9 g/10 min;provided that,the ethylene homopolymer produced in each reactor is removed from the reaction zone prior to being blending together.

19. An extrusion coating process according to claim 18, wherein the ethylene homopolymer produced in a tubular reactor, has a density of 0.914-0.930 g/cc and the ethylene homopolymer produced in a stirred autoclave reactor has a density of 0.914-0.930 g/cc.

20. An extrusion coating process according to claim 19, wherein the ethylene homopolymer produced in a tubular reactor has a polydispersity, Mw/Mn of 8 or more and the ethylene homopolymer produced in a stirred autoclave reactor has a polydispersity, Mw/Mn of at least 10.

21. An extrusion coating process according to claim 20, wherein the polymer blend has a neck-in value of 2.0-5.0 cm at a line speed of 150 ft/min.

22. An extrusion coating process according to claim 21, wherein the polymer blend has a melt index, I2 of 4-10 g/10 min and a polydispersity, Mw/Mn of 10 or more.