Biaxially Oriented Polyethylene (BOPE) Films Fabricated via Tenter Frame Process and Applications Thereof

Yijian Lin, Justice Alaboson, Jian Wang, Karlheinz Hausmann, JingyiXu, Jianping Pan, Xiao-Bing Yun, Mehmet Demirors, Shouren Ge

DowDuPont

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Outline

• BOPE made via tenter frame process

• Crystal orientation of BOPE films

• BOPE film properties

• BOPE applications

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Conventional Fabrication Processes to Make PE Films

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Cast Film Process Blown Film Process

Orientation occurs in the molten state of a polymer

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Tenter Frame Process

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• Orientation occurs in

semi-solid state

• No tenter frame line

specifically designed for

PE

• Typical BOPP line has 5x

MDO and 9x TDO

• Conventional PE cannot

be processed through

BOPP line due to its poor

stretchability

MD

TD

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Selection of PE Grade for Tenter Frame Process

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ResinMI

(g/10min)

Density

(g/cc)

PE-1 1.7 0.926

PE-2 1.6 0.925

• Specific resin design is required

for biaxial orientation

• Orientation temperature window

determines resin processability

x Unorientable temperature

O Orientable temperature

Orientation window was measured with a Brückner Karo IV lab stretcher with a 4x8 draw ratio.

PE-1

PE-2

DSC

heating

MD

TD

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Crystal Orientation of Un-oriented Sheet (WAXS)

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90

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110

020

200

PE crystals are randomly

oriented in the cast sheet before

biaxial orientation

110

020

200

110

020

200

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Crystal Orientation of 5x9 BOPE Film (WAXS)

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110

020

200

Two predominant orientation modes:

• a-axis (200 plane) orients in ND.

• 110 plane orients in ND.

110

020

200

110

020

200

Film was made on commercial BOPP line with 5x in MD and 9x in TD

G.C. Adams, J. Polym. Sci: Pt A-2, 9, 1235 (1971).

N.S.J.A. Gerrits, R.J. Young, J. Polym. Sci.: Pt B, 29, 825 (1991).

A. Ajji, X. Zhang, S. Elkoun, Polym. Eng. Sci., 46, 1182 (2006).

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90

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Crystal Orientation (SAXS)

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MD

TD

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MD

TD

Un-oriented Sheet

Shish-kabab structure is observed in BOPE with shish in MD and CD. Long period in TD (24.8 nm) is greater than in MD (21.7 nm)

BOPE Film

L= 17.2nm

L= 24.8nm

L= 21.7nm

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Crystal Morphology Change during Biaxial Orientation

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• In MDO, the crystals transform into highly oriented, fibrous structure of the shish-kebab type. The c-axis of the crystal is predominantly oriented in MD.

• In TDO, the close-packed shish–kabab fibers separate, re-oriented, and form a large population of thin fibrils with c-axis oriented in TD.

• 110 and 200 planes of the crystals are parallel to the film surface.

MDO to 5x TDO to 9x

MD

TDND

110 or 200 plane

parallel to film surface

L =

21.7

nm

L = 24.8nm

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Modulus

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• 1.8x improvement in MD modulus and 2.5x improvement in TD modulus.

• The 40 μm BOPE film has

a similar stiffness to the 90 μ m blown film, which

allows downgauging.

1.8x

2.5x

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Dart Impact

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1.9x

• The dart impact standard test mimics a package dropped onto the ground from a certain height

• The BOPE film shows 1.9x higher dart impact than a blown film though it is much thinner

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Puncture Test

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• The puncture test measures the resistance of a packaging material to a sharp object inside or outside of the package.

• BOPE film shows 2.3x improvement in puncture force.

2.3x

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Easy Tear

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• Lower tear of BOPE film allows consumers to open the package more easily.

• Lower tear of BOPE film is due to its highly oriented shish-kebab type of morphology.

Tear

path

L. Liu, M. Demirors, R. Patel, B.H. Choi, K.

Anderson, ANTEC, 1346 (2008).

Y.J. Lin, M. Demirors, J.P. Pan, X.B. Yun,

ANTEC, 1477 (2014).

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Optical Properties

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Low

er

= B

ett

er

Haze Gloss

Hig

her

= B

ett

er

• Lower haze and higher gloss for BOPE film, which can be attributed to its smaller shish-kebab type of crystals and smooth surface.

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BOPE vs. Conventional Blown PE

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BOPE vs. Oriented Polymers

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• Most balanced performance

• High clarity & high toughness

• Heat sealable & easy to recycle

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Replace BOPA in Liquid Stand-up Pouch (SUP)

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BOPET 12μm

TF-BOPE 25μm

PE Film

60~140μm

BOPET 12μm

BOPA 15μm

PE Film

70~150μm

SUP for liquid detergent

• 0.5~2L SUP with or without spout

• BOPET//BOPA//PE 3-ply structure

• BOPA in core play for toughness

• Drop test under various conditions

Incumbent

structure

New

structure

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Simulation & Experiment on 1.5L TF-BOPE Based SUP

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BOPET

TF-BOPE 25μm

PE Film

120μm

BOPET

BOPA 15μm

PE Film

130μm

3.0m Pass 3.3m Local Failure 3.5m Failure at Seal

Drop from 3.3m - Passed

Predicted critical height: 3.3~3.5m;

Experimental critical height: 3.45m

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Great Success on Liquid Detergent SUP

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XUS 59910.08 TF-BOPE Film

Film

Producer

Laminated Film

Packaging

Convertor

Benefits

Lower cost

Excellent abuse resistance

Good sealing performance

Lower conversion wastage

Packaging TestNew

Structure

Single Bag Drop(1.5m) PASS

Compressive Test(150kg, 1min) PASS

Whole Box Drop (1m)(6 Pack x 1L, Room Temp) PASS

Whole Box Drop (1m)(6 Pack x 1L, 0°C) PASS

>50MM

Packs

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Open Our Mind & Challenge Our Imagination

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Printing

Substrate

Frozen

Packaging

Metallized

Film

Label

Stock

All PE

………

Thank You

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