DEVELOPMENT OF CHEMICAL MARKERS - …. Peter Reinig... · Development of chemical markers and...
Transcript of DEVELOPMENT OF CHEMICAL MARKERS - …. Peter Reinig... · Development of chemical markers and...
www.polymark.org
DEVELOPMENT OF CHEMICAL MARKERS
Peter Reinig – Fraunhofer IPMS ([email protected])
Polymark Training & Webinar 15 March 2017
Petcore Europe Premises, Brussels
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Note:
Development of chemical markers and marker characterization has been performed by
(Dr. Laura Pilon & Dr. Angela Stewart)
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POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
• Marking concept & marker criteria
• Marker development & evaluation process
• Marker addition
• Marker removal
• Summary
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What is on the agenda ?
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
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How to sort food contact PET ?
MARK it !
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
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Target closed-loop process
Food contact marking
• Positive identification • Fewer incidences of non-
food PET in food PET recycling stream
• Fewer marker options (must be food contact approved)
• Food contact recycling stream higher value
• Better take-up of marker use
• Negative identification • More marker options
(non-food contact) • What is the benefit for
manufacturers to include the marker?
• Greater potential for mistakes
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Coding Methods
1. Single marker for each characteristic of interest a) Minimum of 2 markers needed, more markers gives more options for
identification i. Food/non-food ii. Simple/Complex (e.g. barrier, additives, blends)
b) Not efficient in terms of number of markers vs number of codes 2. Binary code
a) More efficient in marker numbers i. 2 markers allows coding of 3 characteristics (plus blank) ii. 3 markers allows coding of 7 characteristics (plus blank)
3. Ratio code – binary extended by use of different relative intensity of marker signals a) 2 markers in different ratios allows coding of 6 or more characteristics b) Very efficient in number of markers required c) Challenging in terms of marker stability and instrumentation
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Choice of coding method depends on the number of suitable markers available
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• Food contact approved
• Suitable spectral features in UV/NIR (or fluorescence)
• High thermal stability (compounding)
• Removal of marker must be possible
• Commercial availability in suitable quantities
• No change of product appearance (e.g. colour)
Chemical Marker Selection Criteria
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 8
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
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• Develop & characterize suitable marker(s)
• Apply the marker :
coating (of preform / after blow mold)
immersion in bulk (additive for preform)
on label
physical imprint
• Optically detect the marker :
UV (absorption)
VIS (fluorescence)
NIR (absorption)
How to mark PET ?
Marker blended with polymer
No major changes to bottle production process
No additional tooling Analysis can occur at any
point during sorting process
May get interference from polymer and other additives
Direct contact with bottle content
Difficult to detect low concentrations
Expensive to add high concentrations
More difficult to remove
Pros Cons
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Coating on bottle
Physical removal easier Thermal stability not so critical Less interference from polymer
and other additives Easier to detect Smaller amount of marker
required, lower cost Limited contact of coating
material with bottle contents
Another production step Coating may not be
sufficiently durable Need to carry out chemistry
to incorporate marker into coating more permanently (affects food contact approval)
Pros Cons
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 11
Label on bottle
Physical removal easier Thermal stability not so
critical
Article needs to be oriented correctly to enable accurate sorting
Labels typically come off too easily
Pros Cons
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 12
Marker Evaluation Methods & Criteria
• Optical properties – UV/Visible absorbance
• Ideally no/limited absorbance in visible (i.e. no strong colouration) and UV absorbance in range 300-400 nm
– Visible fluorescence • Maximum in range 450-700 nm
– NIR reflectance • Ideally in range 800-2500 nm
• Chemical, thermal, mechanical properties
– Solubility/dispersibility/miscibility • Water insoluble markers ideal for beverage bottle coatings due to low
migration – Thermal stability
• Degradation temperature >280oC required for PET compounding
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 13
Chemical marker evaluation process
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Food contact approval
Optical response
Stability
Capability
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Food contact approval
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 15
approximately 130 potential markers/families evaluated
Desk-based literature & database study
reference frame COMMISSION REGULATION (EC) No 282/2008 on recycled plastic materials and articles intended to come into contact with foods and amending Regulation (EC) No 2023/2006 COMMISSION REGULATION (EU) No 10/2011 on plastic materials and articles intended to come into contact with food (lists more than 800 food contact materials)
Chemical marker evaluation process
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Food contact approval (130)
Optical response (16)
Stability
Capability
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Optical spectral properties of PET
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Transmission
Reflection
UV VIS NIR
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Optics: UV (200-400 nm)
High sensitivity Potentially low cost Degradable under high
dose UV exposure
Interference from PET limits useful wavelength range
Interference from other UV absorbers (e.g. stabilisers)
Pros Cons
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Optics: NIR (800-2500 nm)
Good penetration into material
Broad wavelength range available
Wide range of possible compounds as for mid-IR
Detection technology already in place
Interference from polymer and any other additives
Low marker signal Expensive detector
technology (compared to UV/VIS)
Pros Cons
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visual in daylight under UV light (365 nm)
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Spectral Properties of Markers
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Chemical marker evaluation process
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Food contact approval (130)
Optical response (16)
Stability (6)
Capability
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Marker Addition & Stability
Compounding
• High thermal stability needed
• Easy to add to polymer using a masterbatch approach
• Difficult to remove • Limited investment at
manufacturing stage • High investment at recycling
stage
Coating
• Lower thermal stability requirement
• Easy to apply (e.g. spray, dip, curtain)
• Easy to remove • Higher investment at
manufacturing stage • Limited investment at
recycling stage
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 22
Thermal Stability of Markers
• 4 markers showed sufficient thermal stability to be used directly in extrusion compounding with PET
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 23
Degradation temperature >280oC required for PET compounding
Sample Number
Thermal decomposition temperature Td (onset °C)
4 326 5 292 7 305
12 293
Marker addition – compounding into PET
• Test miscibility of markers with PET and thermal stability to process conditions – Masterbatch approach – 1%, 0.1%, 0.01% – Markers 4, 5, 7 & 12 – Standard PET processing conditions
• Measured melt temperature 285oC
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 24
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Marker + PET (0.1%, 0.01%) in daylight
Marker + PET (0.1%, 0.01%) and virgin PET under UV light 365 nm 25
4 5 12 7
Marker addition – compounding into PET
Solubility of Markers
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Sample Number
Solubility Water
Solubility Ethanol
Solubility Acetone
Solubility Dichloromethane
4 sl sl i i
5 s s i i
6 i i sl s
7 i i i i
8 i i sl s
9 sl s s
10 sl s s i
11 i i sl s
12 i i sl s
13 i s s
14 s s sl
15 i s s s
16 i i sl s
17 i s
18 i s
Solubility : s = soluble, sl = slightly soluble, i = insoluble
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Marker addition – coating onto PET
• Requirements – Water-based formulation; Water resistant in use; Removable in caustic wash
mixtures; Suitable for food contact • Solution
– Acrylic copolymer with ionised acid groups (volatile alkali)
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 27
Marker addition - coating onto PET
• Due to high hydrophobicity, additives needed to disperse marker pigment in water
• Stable dispersion (dilution and coating formulation) achieved using a combination of the following ingredients with centrifugal mixing:
– Solsperse 46000
hyperdispersant – BYK 012 defoamer – Tween 80 stabiliser
ID
Mar
ker
[Mar
ker]
w
t%
[Sol
sper
se
4600
0] w
t%
[BYK
012]
w
t%
[Tw
een
80]
wt%
D7 7 35.1 7.3 0.7 0.7
D12 12 47.2 9.4 0.5 0.5
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 28
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Marker addition : coated PET bottles for lab tests
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clear PET 0.1 wt% on clear PET
1.0 wt% on clear PET
marker #7
Testing of coated PET bottles for lab tests
• Colour (Petcore rPET protocol) – 0.1wt% marker – 1.0 wt% marker
• Water resistance (ASTM) – Ambient – 38oC – clouding (temporary)
• Detergent resistance (ASTM) – Ambient – 74oC – clouding (permanent)
• Adhesion (ASTM) – Cross-hatch tape test
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 30
Compounded
• Thermal degradation - Degradation products remain
• Photochemical reaction - Degradation
• products remain in material - Dimerisation/isomerisation/ rearrangement
• Products of unknown toxicity
• Chemical degradation - e.g. addition of catalyst during
re-extrusion • Degradation products remain
• Extraction - PET resistant to extraction
processes
Coated
• Washing - Solvent process - Water-based (alkaline process)
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 31
Marker Removal
Marker Removal
Evaluation by visual inspection under UV lamp (365 nm)
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme 32
Coated PET flakes (1.0wt%)
marker #7
after 10 min. washing in 2%NaOH (60°C) + hot water rinse
after 10 min. washing in 2%NaOH (60°C) + caustic rinse
Where are we now ?
4. Suitable for compounding with PET or coating, strongly coloured, water soluble 5. Suitable for compounding with PET or coating, some visible fluorescence, water soluble 6. Envirotoxin, potential allergen 7. Suitable for compounding with PET or coating, strong fluorescence, strong
colour, water insoluble 8. Envirotoxin 9. Already used in PET as a scavenger for acetaldehyde, potential allergen 10. No suitable spectral signature, only EFSA approved as “monomer”, envirotoxin 11. UV absorber, no fluorescence 12. Suitable for compounding with PET or coating, strong fluorescence,
practically colourless, water insoluble 13. Visible fluorescence, suitable for coating 14. Visible fluorescence, suitable for coating, water soluble 15. Visible fluorescence, suitable for coating 16. UV absorbance/no fluorescence 17. Too volatile, fragrance (migration?) 18. Too volatile, fragrance (migration?) 19. No commercial supplier could be found
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
16 markers reduced to 6
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Chemical marker evaluation process
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Food contact approval (130)
Optical response (16)
Stability (6)
Capability
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Markers : Further Downselection
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
• λmax(7) ≈ 490 nm (see above) as dispersed pigment (no coating matrix)
• λmax(7) ≈ 400, 430, 450 nm as dissolved dye in solvent [Plastics Additives & Compounding, 2003, 5, 42-46]
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• PET and #9 fluorescence are coincident as expected, #9 also overlaps
• #7 and #12 are well separated at peak maxima and high intensity
• Other shortlisted markers had insufficient fluorescence intensity (#4, #5, #13, #15)
• PET/#9 fluorescence and presence of other optical brighteners interferes with marker #14
4 7
12 14 9 PET
• PET and #9 fluorescence are coincident as expected, #9 also overlaps
• #7 and #12 are well separated at peak maxima and high intensity
• Other shortlisted markers had insufficient fluorescence intensity (#5, #13, #15)
• PET/#9 fluorescence and presence of other optical brighteners interferes with marker #14
Markers : Further Downselection
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
• λmax(7) ≈ 490 nm (see above) as dispersed pigment (no coating matrix)
• λmax(7) ≈ 400, 430, 450 nm as dissolved dye in solvent [Plastics Additives & Compounding, 2003, 5, 42-46]
6 markers reduced to 2
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4 7
12 14 9 PET
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
Marker of choice : 4,4’-bis(2-benzoxazolyl)stilbene
marker #7
COMMISSION REGULATION (EU) No 10/2011 on plastic materials and articles intended to come into contact with food
Food contact approval:
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Summary
• Within POLYMARK we identified proper candidates for chemical food-contact approved markers :
• Markers can be used both for compounding and coating
• Flexible, temporary marker addition with coating approach
• Removal of coated marker by existing recycling plant washing (NaOH)
• Marker detection using inexpensive UV-excitation/VIS-fluorescence
POLYMARK (311777) is funded by the European Community’s Seventh Framework Programme
More details: Removable Identification Technology to Differentiate Food Contact PET in Mixed Waste Streams
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