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November 2009 Dr. Claudia Meckel-Jonas TAPPI conference India1
Polyurethane Laminating Adhesivesand Food Safety: A Smart Alliance
Dr. Claudia Meckel-JonasHenkel Company China Ldt.
Flexible Packaging Symposium India 2009
November 2009 Dr. Claudia Meckel-Jonas TAPPI conference India2
Flexible packaging
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Sustainable packaging system
Source:
EnvironmentResources
EconomyCost for production
distribution, merchandizing of goods
SocialMeet customer expectations
•Product protection•Safety
•Handling•Information
Packagingwith adhesives
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PAA in food!
So called “Danish food scandal”
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Laminating adhesivesPolyurethane (PUR) chemistry
• Advantages
• Performance
• Price
• Availability
• Established equipment
• Disadvantages
• Interaction with films/inks/additives
R-NCO + HO-R‘ R-NH-CO-O-R‘Urethane
• Curing needs time
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Production stage
Days0
1st lamination
slitting
heat sealing
boiling resistance
retort resistance
Physical Curing
Curing time
high performance
medium performance
standard performance
safe for food contact ?
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We have to get the
chemical curing the physicalof the adhesives requirements
balanced for a sustainable and safe packaging.
&
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Curing mechanism of2-c polyurethane adhesives• First curing step: Reaction of NCO with OH
Polyurethane prepolymer after first curing step
NH
NCO N C ONH
O OC
O
C
O
IsocyanateIsocyanate AlcoholAlcohol
UrethaneUrethane
N C ONCO HO OH+
N C ONCO N C ONCO N C ONCO
N C ONCO
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• Final curing (1): Reaction of NCO with H2O
IsocyanateIsocyanate WaterWater
H2O+NH
NCO N C ONH
O OC
O
C
O
Curing mechanism of2-c polyurethane adhesives
UrethaneUrethaneUreaUrea
NH
NH
NH
NH
O OC
O
C
O
CNH
O
CNH
O
Completely cured polyurethane adhesive
N C ONCO
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Flexible packaging in contact with food
Adhesive in indirect food contactOuter Layer Adh. Sealing Layer
Monomeric MDIE.g.:
NCO + Water ⇒
Aromatic Amines
“PAA”
Food
ONLY present in not fully cured PUR-adhesives !
Suspected to be carcinogenic
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Migration of aromatic amines in screening test – cited in BfR XXVIII
141,4 mm
141,
4 m
m
Sample from reel Make pouch (200cm²) + 100ml acetic acid
Store in oven2h@70°C
Derivatisation of filling UV-Detection
Chemistry!Chemistry!
November 2009 Dr. Claudia Meckel-Jonas TAPPI conference India12
1,120 ppb 600 ppb 120 ppb 76 ppb 28 ppb 12 ppb < 2 ppb
PAA-Migration: Photometric Test (BfR)
• Colour intensity corresponds to level of migration of non-reacted NCO-monomer!
• Detection limit: 2ppb!
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PAA Migration Level
Days0
1st lamination
slitting
heat sealing
Oiling resistance
retort resistance
Chemical Curing - Conventional
0
1st lamination
Conventional System
Curing time
high performance
medium performance
standard performance
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Cure mechanism of a modified2-component PUR with smart chemistry
Cure mechanism
----urea------urethane------urea------fully cured PUR
NCO/OH>1based on mix ratio
with free MDI-monomerOCN-----------NCO + HO------OH
step 1: fast
step 2: slow+ water- carbon dioxide
OCN-------urethane-------NCOno retain NCO-monomer safe for indirect food contact
November 2009 Dr. Claudia Meckel-Jonas TAPPI conference India15
PAA Migration Level
Days0
1st lamination
slitting
heat sealing
Oiling resistance
retort resistance
Chemical Curing - Smart
0
1st lamination
Conventional System
Smart System
Curing time
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EC Regulations for safe food packaging
EC 1935/2004framework
2002/72/ECPlastic directive
(90/128 + amendm.)
82/711+amendments
time/temp. 85/572food simulants
amendments2004/1/EC2004/19/EC2005/79/EC2007/19/EC
5th amendment2008/39/EC
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Flexible packaging in food contact Legal requirements
• framework regulation 1935/2004/EC
• directive plastics2002/72/EC and amendments (actual change: 2007/19/EC)
• FDA § 175.300direct food contact
• FDA § 175.105indirect food contact
• FDA § 177.139540°C – 120°C
• FDA § 177.1390> 120°C
• LFGB
• BedGgstV
• BfR Recommen-dation XXVIII for cured poly-urethanes as adhesive layers for food packaging
• GB 9685-2008
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Framework Regulation 1935/2004/EC
EC 1935/2004 (replaced 89/109), Article 3:
Packaging materials have to be manufactured in a way that
under the conditions of use no components will be transferred into the food, which
• are a potential hazard to the human health
• change the food composition or
• influence the organoleptic properties
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EC migration limit for aromaticamines & BfR-method - Conclusion
We recommend to use the BfR-method for compliance testing using a limit of 2ppb
Otherwise there will be the risk of non-conformity with EU-legislatives!
2
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Limitations of „BfR-test“
• SUMMARIZING method• All PAA are measured at once
• Known to give false positive results!!!• No distinction between PAA and others substances
possible.
• Problematic in presence of additives (films/ink)
• Results for retort applications & higher temperatures are doubtfull and have to be cross-checked
A specific method is required for cross-check!
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Summary: Compliance testing forPAA
4th amendment of 2002/72/EC: 2007/19/ECDL=0,01 mg/kg (aniline, without analytical tolerance)
compliance testing
Screening methodBfR photometric test
threshold of action limit0,002 mg/kg
considers lower responsefactors of real PAA vs aniline
Specific methodHPLC-UV
if >0,002 mg/kg DL = sum PAA <0,01mg/kg
2 10
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Factors Influencing Migration Time
• Adhesive system• free monomeric isocyanate content• Curing mechanism (most important)• coating weight• Mix ratio
• Laminating AND storing conditions• Temperature• Humidity• Thickness of rolls• Width of rolls
• Film• Type• Thickness• Additives (e.g. copolymers (EVA), pigments..)• Type of film for outer layer
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Conclusion
• Laminates should not be used for food packages until physical AND chemical curing is completed!
• Packages, that do not comply with legislatives endanger human health.
• The answer is....
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…responsible care…training and information of converters…the choice of the smart & appropriate adhesive!
Henkel CAC India and
will help to meet the demands of safe food packaging!!