Machine direction oriented films comprising multimodal copolymer of ethylene and at least two alpha-olefin comonomers

Patent metadata

Field	Value
Publication number	US-11186706-B2
Application number	US-201716097319-A
Country	US
Kind code	B2
Filing date	Apr 28, 2017
Priority date	Apr 29, 2016
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

A machine direction oriented film comprising a multimodal copolymer of ethylene and at least two alpha-olefin-comonomers having: a) a density of from 906 to 925 kg/m3 determined according to ISO 1183, b) an MFR21 of 10-200 g/10 min determined according to ISO1133, wherein the multimodal copolymer of ethylene comprises c) a first copolymer of ethylene and a first alpha-olefin comonomer having 4 to 10 carbon atoms; and d) a second copolymer of ethylene having an alpha-olefin comonomer different from the first copolymer, said second alpha-olefin comonomer having 6 to 10 carbon atoms.

First claim

The invention claimed is:

1. A machine direction oriented (MDO) monolayer film comprising a multimodal copolymer of ethylene and at least two alpha-olefin-comonomers having:
a) a density of from 906 to 925 kg/m 3 determined according to ISO 1183,
b) an MFR 21 of 10 to 200 g/10 min determined according to ISO1133,
wherein the multimodal copolymer of ethylene comprises

c) a first copolymer of ethylene and a first alpha-olefin comonomer having 4 to 10 carbon atoms; and
d) a second copolymer of ethylene having an alpha-olefin comonomer different from that of the first copolymer, said second alpha-olefin comonomer having 6 to 10 carbon atoms; and

wherein the machine directed oriented monolayer film has been stretched uniaxially in the machine direction (MD) in a draw ratio of at least 1:1.5.

2. The MDO monolayer film as claimed in claim 1 which has been stretched uniaxially in the machine direction (MD) in a draw ratio of at least 1:2.

3. The MDO monolayer film as claimed in claim 1 wherein the multimodal copolymer of ethylene comprises
50 wt % or less of the first copolymer of ethylene;
50 wt % or more of the second copolymer of ethylene.

4. The MDO monolayer film as claimed in claim 1 wherein the first copolymer of ethylene has
i) a density of from 945 to 955 kg/m 3 ; and
ii) a melt flow rate MFR 2 of 150 to 1500 g/10 min.

5. The MDO monolayer film as claimed in claim 1 wherein the second copolymer of ethylene has a density of ≤903 kg/m 3
when calculated according to Equation 5 based on values determined according to ISO 1183:
ρ b =w 1 ·ρ 1 +w 2 ·ρ 2   Equation 5,

where ρ is density in kg/m 3 , w is weight fraction of component in a mixture and subscripts b, 1 and 2 refer to the mixture b, component 1 (first copolymer) and component 2 (second copolymer), respectively.

6. The MDO monolayer film as claimed in claim 1 wherein the second copolymer of ethylene has MFR 21 of <20 g/10 min when calculated according to Equation 4: Hagström formula:

MI
b

=

(

w
·

MI
1

-

w

-
b

a

+

(

1
-
w

)

·

MI
2

-

w

-
b

a

)

-
a

·

w
b

,

Equation
⁢

⁢
4

where a=10.4, b=0.5 for MFR 21 , w is the weight fraction of the polymer component having higher MFR, MI b is the MFR 21 of the second copolymer mixture, MI 1 is MFR 21 of a first copolymer of ethylene, and MI 2 is MFR 21 of the second copolymer of ethylene.

7. The MDO monolayer film as claimed in claim 1 having a thickness of 10 to 30 microns after stretching.

8. The MDO monolayer film as claimed in claim 1 having one or more of:
an Elmendorf tear resistance of at least 310 N/mm in the TD;
an Elmendorf tear resistance of at least 90 N/mm in the MD;
a normalised peak force of 2000 to 3500 N/mm;
a normalised energy to peak force of 30 to 120 J/mm; and/or
a normalised total penetration energy of 30 to 90 J/mm.

9. The MDO monolayer film as claimed in claim 1 wherein the first copolymer of ethylene has
i) a density of from 945 to 955 kg/m 3 ; and
ii) a melt flow rate MFR2 of 150 to 1500 g/10 min.

10. A machine direction oriented (MDO) film comprising a multimodal copolymer of ethylene and at least two alpha-olefin-comonomers having:
a) a density of from 906 to 925 kg/m 3 determined according to ISO 1183,
b) an MFR 21 of 10 to 200 g/10 min determined according to ISO1133,
wherein the multimodal copolymer of ethylene comprises

c) 35 to 50 wt % of a first copolymer of ethylene comprising at least a first and a second fraction; said first fraction comprising ethylene and a first alpha-olefin comonomer having 4 to 10 carbon atoms and said second fraction comprising ethylene and the first alpha-olefin comonomer having 4 to 10 carbon atoms said first and second fraction are present in a weight ratio of 2:1 up to 1:2; and
d) 50 to 65 wt % of a second copolymer of ethylene having an alpha-olefin comonomer different from the first copolymer, said second alpha-olefin comonomer having 6 to 10 carbon atoms; and

wherein the machine directed oriented film has been stretched uniaxially in the machine direction (MD) in a draw ratio of at least 1:1.5.

11. A machine direction oriented (MDO) film according to claim 10 , wherein component (d) comprises a second copolymer of ethylene having an alpha-olefin comonomer different from the first copolymer having a density of below 900 kg/m 3 when calculated according to Equation 5, based on values determined according to ISO 1183:
ρ b =w 1 ·ρ 1 +w 2 ·ρ 2   Equation 5,

where ρ is density in kg/m 3 , w is weight fraction of component in a mixture and subscripts b, 1 and 2 refer to the mixture b, component 1 (first copolymer) and component 2 (second copolymer), respectively.

12. The MDO film as claimed in claim 10 wherein the first and

Assignees

• Borealis Ag

Inventors

• Tran Anh Tuan
• Cavacas Paulo
• Gensous Audrey

Classifications

• C08L23/08

  Copolymers of ethene (C08L23/16 takes precedence) · CPC title

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title

• B32B27/32

  comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)} · CPC title

• C08F4/65916

  supported on a carrier, e.g. silica, MgCl2, polymer · CPC title

• B29C48/0018

  combined with shaping by orienting, stretching or shrinking, e.g. film blowing (B29C48/0017 takes precedence) · CPC title