Novel polyethylene films

• US 20030229182A1
• Filed: 06/23/2003
• Published: 12/11/2003
• Est. Priority Date: 06/01/2000
• Status: Active Grant

• Current Assignee: Ineos Sales (Uk) Limited (Ineos AG)
• Original Assignee: BP Chemicals Ltd. (BP PLC)
• Inventors: Gilbert, David George, Alarcon, Frederic, Frye, Christopher James, Turtle, Brian Leslie
• Granted Patent: US 6,998,440 B2
• Time in Patent Office: Days
• US Class Current: 525/191
• CPC Class Codes: C08J 2323/08 Copolymers of ethene C08J2323/16 takes precedence
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08L 2205/02 containing two or more polymers of the same C08L -group
• CPC Class Codes: C08L 23/0815 Copolymers of ethene with aliphatic 1-olefins
• CPC Class Codes: C08L 23/22 Copolymers of isobutene; Butyl rubber ; Homo- or copolymers of other iso-olefins
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof

Abstract

Novel stretch and blown films are prepared based on copolymers of ethylene and alpha-olefins having (a) a density in the range 0.900 to 0.940 (b) an apparent Mw/Mn of 2-3.4 (c) I₂₁/I₂ from 16 to 24 (d) activation energy of flow from 28 to 45 kJ/mol (e) a ratio Ea(HMW)/Ea(LMW)>1.1, and (f) a ratio g′(HMW)/g′(LMW) from 0.85 to 0.95. The films exhibit an excellent combination of strength and processability and are particularly suitable for use as either stretch films or blown films for use as heavy duty sacks. The preferred films show a dart impact of >1100 g and MD elongations of >500 %.

Claims

1. A stretch film comprising a cling additive in amount >

0.5% and having

(a) dart impact of >

450 g

(b) MD tear strength of >

190 g/25 μ

m

(c) MD elongation at break of >

450%,

said film comprising a copolymer of ethylene and an alpha-olefin having from 3 to 10 carbons atoms, said copolymer having

(a) a density in the range 0.900 to 0.940

(b) an apparent Mw/Mn of 2-3.4

(c) I₂₁/I₂ from 16 to 24

(d) activation energy of flow from 28 to 45 kJ/mol

(e) a ratio Ea(HMW)/Ea(LMW)>

1.1, and

(f) a ratio g′

(HMW)/g′

(LMW) from 0.85 to 0.95.

2. A stretch film according to claim 1 having a dart impact >

600 g.

3. A stretch film according to either of the preceding claims having a dart impact >

1100 g.

4. A stretch film according to any of the preceding claims having a MD elongation of >

500%.

5. A stretch film according to any of the preceding claims wherein the cling additive is present in amount >

2%.

6. A stretch film according to any of the preceding claims wherein the cling additive is polyisobutene (PIB).

7. A blown film having

(a) dart impact of >

450 g

(b) MD tear strength >

190 g/25 μ

m

(c) MD elongation >

450%

said film comprising a copolymer of ethylene and an alpha-olefin having from 3 to 10 carbons atoms, said copolymer having

(a) a density >

0.920,

(b) an apparent Mw/Mn of 2-3.4

(c) I₂₁/I₂ from 16 to 24

(d) activation energy of flow from 28 to 45 kJ/mol

(e) a ratio Ea(HMW)/Ea(LMW)>

1.1, and

(b) a ratio g′

(HMW)/g′

(LMW) from 0.85 to 0.95.

8. A blown film according to claim 7 having a dart impact >

600 g.

9. A blown film according to claims 7 or 8 having a dart impact >

1100 g.

10. A blown film according to claims 7 to 9 having a MD elongation of >

500 g.