Transcript The effect of Extrusion and Casting process variables on

Stretching the Limits
“The effect of Extrusion and Casting process
variables on Stretch Film Performance”
Marcel van Enckevort
SABIC Polyethylenes BV
SABIC Polyethylenes BV
Introduction
Stretching the . . .
As a converter you can improve your economies of
scale by stretching the output and speed to the limits of
your cast stretch lines.
Limits
— Equipment
— Application
— Resins
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Outline
Introduction
Experimental set-up
— Approach
— Results
— Conclusions
Comparison
— Approach
— Results
— Conclusions
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Cast Stretch Wrap Film segments
Manual Stretch
Automatic Stretch
Power Stretch
100 – 150%
150 – 250%
> 250%
40% Market share
48% Market share
12% Market share
Photos: ITW MIMA Stretch Packaging Systems
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Cast Stretch Wrap Film Cost Structure
Maintenance costs
Labour force
Scrap costs
General Costs
Energy costs
Core costs
Pay-back
Resin Costs
100%
80%
60%
40%
20%
0%
Source: SMS Folientechnik GmbH
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Facts & Figures

Almost 90% of the stretch film demand is in
hand wrap and machine wrap applications

Maximum pre-stretch level up to 250%

More than 80% of your film cost price is
determined by the resins

End users are looking for the lowest price!
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Are you fulfilling your potential?

Are you using optimal outputs/speed?
— Nowadays modern stretch film lines can run at higher speeds
(up to 600 m/min)
— Older stretch film lines can potentially run faster than being
done today!
Note: speed also determines the end film properties

Did you optimise line settings to use the full potential of the
resins?

Are you using fit for purpose resins?
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Approach

Butene-based SABIC® LLDPE 318B (2.8/918)

A state-of-art cast stretch film line

Real world conditions

3-layer film concept A/B/C with 15% VLDPE in cling
layer and 25% trim recycle in the core

Experimental design
15 experiments in 2 days

Easy adjustable variables
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Cast2020: Settings
Dimension
Value
Output
> 1000 kg/h
Winding speed
500 m/min
Die gap
0.6 mm
Film thickness
20 µm
Layer distribution
15/70/15 %
Recycle in core layer
25%
Photo: SMS Folientechnik GmbH
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Cast2020: Settings – Cont.
Photo: SMS Folientechnik GmbH
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Variable
Range
Melt Temp.
250 – 290 °C
Chill roll Temp.
15 – 25 °C
Vacuum box
2 – 4 cm H2O
SABIC® C4-LLDPE Film properties
Improved by changing settings:

Tear resistance TD with 15%

Puncture resistance with 60%

Ultimate pre-stretch level with 37% (from 230 to 340%)
Not influenced by the settings:
 Optical properties (Gloss, Haze)
 Cling
 Elastic recovery (snap back)
 Stress retention (bundling force)
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Ultimate Pre-stretch level (HighLight)
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Real world testing
Semi-automatic Stretch Wrapper
ROBOPAC Rotoplat 705 PVS
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Setting
Maximum
Pre-stretch
400%
Turntable speed
15 rpm
Wrapping speed
60 m/min
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Real world testing – Cont.
Looking for the limits we
found several holes and
film ruptures!
we also found consistent
pre-stretch levels up to
400 %
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Conclusions

Apply optimal processing conditions to utilise the
potential performance present in your C4-LLDPE
based films

Take advantage of the cost price benefits from
maximising the use of C4-LLDPE
Achieve pre-stretch levels up to 400%!!
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Outline
Introduction
Experimental set-up
— Approach
— Results
— Conclusions
Comparison
— Approach
— Results
— Conclusions
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What about the SABIC® C6-LLDPE?

compared SABIC® C6-LLDPE (and C4-LLDPE) with
metallocene based-C6-LLDPE and with C8-LLDPE

Cast2020 cast film line

3-layer film concept A/B/C concept with 15% VLLDPE
in cling layer and 25% recycle in the core

Melt temperature, chill-roll and vacuum box on
midpoint settings
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Results
Pre -st re t ch
100
Elast ic Re co ve ry
Cling
50
0
Te ar TD
Punct ure re sist ance
Dart im pact
Butene
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Hexene
Metallocene
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Octene
Conclusions
Utilising C6-LLDPE can:

Improve relevant film properties (e.g. Tear
Resistance, Puncture Resistance and cling)

$AV€ on the cost of VLDPE (up to 50%) , using
C6-LLDPE in the cling layer!

Easily obtain pre-stretch levels of 250%
And there is still room for improvement!
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Finally
Explore the limits of processing traditional C4 and
C6 based LLDPE resins on your extrusion lines
Apply fit for purpose resins in your film structures
Enjoy the use of SABIC® LLDPE…..
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Acknowledgement
SMS Folientechnik GmbH, Vienna
Polychem Laboratory
HighLight Industries
De Witt ROBOPAC, The Netherlands
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