# US 7,608,327 B2 · High tear strength film

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- Number: US 7,608,327 B2
- Document ID: US7608327B2
- Status: Granted
- Kind: B2
- Application number: 11/312,033
- Filed: 2005-12-20
- Published: 2007-06-21
- Granted: 2009-10-27
- Earliest claimed: 2005-12-20
- Assignees: Equistar Chemicals, LP
- Inventors: Harilaos Mavridis
- Web page: https://patentgrep.com/patent/US7608327B2

## CPC

- C08L 23/06: Polyethylene
- C08L 23/0815: {with aliphatic 1-olefins containing one carbon-to-carbon double bond}
- Y10T 428/263: Coating layer not in excess of 5 mils thick or equivalent
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A thick film produced from a polyolefin blend is disclosed. The film is prepared from a blend having a density from 0.935 to 0.955 g/cm3 and comprising LLDPE and greater than 50% by weight HDPE having a density greater than 0.955 g/cm3. The film has a modulus in the machine direction from about 75,000 to about 130,000 psi and improved machine direction tear strength.

## Claims

### Claim 1

A film produced from a polyolefin blend that has a density from 0.935 to 0.955 g/cm3, said blend comprising:
(a) greater than 50 wt. % of HDPE having a density greater than 0.955 g/cm3 and an MI2 less than 1.0 dg/min.; and
(b) LLDPE having a density from 0.900 to 0.925 g/cm3 and an MI2 less than 5.0 dg/min.;
wherein the film has a thickness from 50 to 200 microns, a modulus in the machine direction (modMD) from about 75,000 to about 130,000 psi, a tear strength in the transverse direction (TSTD) greater than in the machine direction (TSMD), and a TSMD expressed in grams and measured at a film thickness of 100 microns, defined by:
TSMD>1544−(11.2)(modMD/1000 psi).

### Claim 2 (depends on 1)

The film of claim 1 wherein the LLDPE is an ethylene-hexene copolymer.

### Claim 3 (depends on 1)

The film of claim 1 wherein the polyolefin blend has from about 10 to about 49 percent by weight LLDPE.

### Claim 4 (depends on 1)

The film of claim 1 wherein the polyolefin blend is prepared by melt extrusion.

### Claim 5 (depends on 1)

The film of claim 1 wherein the polyolefin blend has a density from 0.940 to 0.950 g/cm3.

### Claim 6 (depends on 1)

The film of claim 1 wherein the LLDPE has an MI2 from 0.5 to 2.0 dg/min.

### Claim 7 (depends on 1)

The film of claim 1 having a thickness from 100 to 200 microns.

### Claim 8

A film produced from a polyolefin blend that has a density from 0.935 to 0.955 g/cm3, said blend comprising:
(a) greater than 50 wt. % of HDPE having a density greater than 0.955 g/cm3 and an MI2 less than 1.0 dg/min.; and
(b) LLDPE having a density from 0.900 to 0.925 g/cm3 and an MI2 less than 5.0 dg/min.;
wherein the film has a thickness from 50 to 200 microns, and a tear strength in the machine direction (TSMD) greater by at least 20% than that of a film with the same modulus prepared from a single polyethylene resin.