Agricultural barrier films Plast09

Agricultural barrier films

DSM Engineering Plastics
Ted Brink | Application Development Engineer Extrusion

Living Solutions for People, Planet and Profit 1


Contents

• Introduction
• Agricultural barrier films
- why barrier films are necessary
- barrier materials
- film compositions
- film property improvement
• Conclusions

Agricultural barrier films - Plast'09 - Plastics & Agriculture Page 2


DSM today

− DSM creates innovative products and services in
life sciences and materials
Pharma Nutrition
− active on 5 continents, more than 250 locations 11% 28%

− approx. 23,000 employees
Performance
− approx. €8.8 billion annual sales in 2007 Materials Polymer
29% Intermediates
− leadership positions in ~75 % of the portfolio Base 15%
Chemicals
& Materials
17%

€ 0.84 bn sales in 2007 and 1,500 employees worldwide
As a leading global supplier of quality engineering plastics
we provide customer value through innovative solutions



DSM EP’s product portfolio for film applications

Akulon® PA6 and PA66 barrier material
Akulon® XP extreme performance PA6
Arnitel® TPC breathable material
Stanyl® high heat resistant PA46
Yparex® maleic anhydride modified polyolefin



Why agricultural barrier films?

Methyl bromide is being used as a fumigant in agriculture

However, MeBr contributes to the depletion of the ozone layer

Application of a barrier film has the following effects:
• reduced emission of MeBr into the atmosphere
• increased effectiviness as fumigant

Methyl bromide is a neurotoxic gas
• odourless
• boiling point: 3.6 °C
• gas density: 3.4 (air = 1)



The ozone hole in 2006

The largest Antarctic
ozone hole recorded
as of September 2006



Montreal protocol 1987

Reduction of methyl bromide developed countries:
• 1998: 25 %
• 2001: 60 %
• 2003: 75 %
• 2005: 100 %

Article 5 countries: 100 % reduction in 2015



Today’s reality

Objectives Montreal will not be reached

• partners granted production of 5.300 tons of methyl bromide
by the USA in 2008

• environmental groups revealed stock of 10.000 tons in USA

• methyl bromide will continue to be used, but volumes will
decrease as alternatives will become available

• alternative fumigants may also require barrier films to
improve efficiency



Containment of emission of fumigant

• prevent emission into the atmosphere by using barrier films
• injection of methyl bromide deep in the soil



Barrier materials

• EVOH
• PA6.66 copolyamide
• PA6 homopolymeer
• PA6 nanocomposite
• blend of PA6 and amorphous PA
• Orgalloy
• coated film (Al, SiO2)



Properties of barrier materials

material barrier price processing mechanical

EVOH +++ -- - +/-

PA6.66 +/- - ++ +

PA6 + + + +

PA6 nano ++ - + -

PA6 AmPA ++ - + +

Orgalloy +/- - + +

coating +++ - - ?


Common film structures

3-layer structure

10 µm (L)LDPE/adhesive
6 µm (co)polyamide
10 µm
(L)LDPE/adhesive

5-layer structure (L)LDPE
adhesive
(co)polyamide
adhesive
(L)LDPE


Adhesive or tie resin (DSM Yparex)

• no adhesion between PE and PA in coextrusion
• MAH-g-PE is commonly used to realise adhesion between
PA and PE
• physical adhesion between MAH-g-PE and PE
• chemical reaction between MAH-g-PE and PA

O O
+ H2N + H2O
O N
O O



Requirements agricultural barrier films

Requirements

• British Pest Control: 1 gram MeBr per m² per hour

• French ministry of Agriculture: 0.2 gram MeBr per m² per hour



Coextrusion blown film process



Film processing

• thin film
• large machines
• large bubble diameter

• compromise in material use:
- LDPE needed for bubble stability
- PA6.66 to realise low polymer temperature

• PA6 good alternative to PA6.66 but higher melting point
• rheology of PA differs from PE



LDPE and LLDPE for barrier film

property LDPE LLDPE
bubble
++ +
stability
impact
+ ++
strength
puncture
+ ++
resistance



Viscosity curves of LDPE and PA6

10000
melt viscosity [Pa.s].

1000
LDPE
Akulon F132
100

No proper viscosity match
10
0.01 0.1
between PE and PA6
1 10 100 1000
shear rate [1/s]



Standard materials result in interfacial instability

Rheology mismatch PA6 and LDPE
processing window
10000
viscosity

1000
PA6
LDPE
100

10
0.01 0.1 1 10
shear rate [1/s]
100 1000
leads easily to problems

Poor elasticity and viscosity match
creates wave effect resulting in poor
optical properties and quality risk

wave length
uniform thickness wavy interface



The Akulon XP solution

Minimizes differences in melt viscosity and elasticity of
coextruded materials
Result: widening of processing window
10000 Akulon XP
Akulon XP shows
shear-thinning
viscosity [Pa.s]

1000
behaviour:
• less motor power at
100 LDPE high rpm
MFI 1.9 • higher zero shear
viscosity
10 • lower Tpol at high
0.01 0.1 1 10 100 1000 output
shear rate [1/s]

wide processing window



Akulon XP for agricultural barrier film - trial

Trials in a 3-layer concept

Objective:
replacement PA6.66 to reduce costs and/or improve properties

total film thickness: 25 µm
COPA layer: 6 µm
PE outerlayers: 60 % LLDPE, 30 % LDPE, 10 % Yparex 9403
bubble diameter: 5.8 meter (BUR 2.1)

Yparex 9403
DSM’s tie resin
MAH-g-PE



Akulon XP for agricultural barrier film - results

Replacement of PA6.66 with Akulon XP36-E1:

• LDPE could be omitted while maintaining bubble stability and
improving mechanical properties
or

• bubble diameter could be increased from 5.8 to 7 meter
(BUR 2.8) or

• thickness PA layer could be reduced from 6 to 5 µm while
maintaining mechanical and barrier properties



Conclusions

Akulon XP PA6 in agricultural barrier films results in:

• improved bubble stability

• improved mechanical properties

• improved output (larger BUR)

• cost reduction



THANK YOU FOR YOUR ATTENTION

More information:
Ted Brink
Application Development Extrusion
Tel: (31)464767831
e-mail: ted.brink@dsm.com

www.dsmep.com
www.akulon.com
www.yparex.com

Visit us at Hall 20, booth D31

Living Solutions for People, Planet and Profit 24


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