UV Inkjet Printing on Food Packaging: State-of-Art...

UV Inkjet Printing on Food Packaging: State-of-Art and Outlook

uv.eb WEST 2015

Crowne Plaza Hotel & Marina Redondo Beach, CA

Roel De Mondt, PhD Agfa-Gevaert N.V., Belgium

[email protected]

2 R De Mondt 10 March 2015

Analog or digital ?

•  Why printing ? ! decoration, information, marketing, identification…

•  Analog printing: •  Examples: gravure printing, pad printing, offset printing, flexography, screen

printing, … •  Master to be made for each print colour •  Fixed setup cost divided by number of prints ! preferably large print runs

•  Digital printing •  Laser/toner/EP vs. inkjet


ABC of inkjet printing

•  Digital, non-contact printing method •  no master (plate or sleeve) •  direct from image file to substrate

•  Ink properties for jetting process •  No 1 = low viscosity,…

•  Ink properties for application •  surface tension for image quality •  UV curable for non-absorbing substrates •  …


Low migration inks

•  Packaging printing •  Indirect printing (printing on the non-contact side)

•  Primary food packaging (food and beverages) •  Direct on “food container” •  Lids and closures •  Pouches •  Foils (wrap, flexible, laminates, …)

•  Labels •  Secondary food packaging

•  Pharmaceutical packaging •  Direct print on medical bag, syringes, etc •  Foils (mostly alu based blisters) •  Secondary packaging


Direct printing

•  Label printing vs. Direct Printing •  Label printing = 3 steps

•  Step 1 : printing of product information on label (roll) •  Step 2 : mount printed label roll on applicator •  Step 3 : label application

•  Direct printing = 1 step •  Direct print of product information on the packaging •  Advantages: no label stock, no master, variable run length, fast change of product information

(“on the fly”), variable data, …

•  Direct print on food packaging •  Direct print with UV LM inks on the primary food packaging

•  e.g. “food container”

! highest demand to LM inkjet inks for jetting, physical properties and low migration


Value proposition

Drink Manufacturer

stock Label printer

Bottle manufacturer

stock

glue

logistics

fill ship

State-of-the-Art

Innovation Drink Manufacturer

Bottle manufacturer

stock

fill ship inkjet

label order design Delay

Value proposition = JIT + Cost effective Solution

Cost Cost


What is a Low Migration ink ?

Food safe packaging

Combination and control of all parts of the print solution Food packaging printing needs to be a controlled process

“There is no such thing as LM inks” An ink can have intrinsically beneficial properties for LM An ink is expected to be able to yield a safe food packaging if the necessary precautions of e.g. curing (dose,

UV type, …) have been taken.

Environmental conditions

LM UV-curable inkjet ink

Printing and process

conditions

Substrate (barrier quality)


Low migration system concept

Food type

Substrate type

Amount of ink + curing

Toughest applications

barrier quality

water ! alcoholic

beverage ! oil based

only variable info or

full label information


Sustainability via digital printing for food packaging

Communication

Accessible health information

QR

Food safe print VOC

Substrate scrap

Transportation

Warehousing

Environment

Short run

Lead times

Sustainable Digital printing

LED

Recycling


Food safety

ENDANGER HEALTH

CHANGE SMELL TASTE


Primary Food Pack: Overview of “legislations”

•  Ink specifications: •  Swiss Ordinance 817.023.21, German Bedarfsgegenstand ? •  EuPIA Guideline on Printing Inks applied to the non-food contact surface of food packaging

materials and articles •  EuPIA Exclusion List for Printing Inks and Related Products •  EuPIA Suitability List of Photo-Initiators for Low Migration UV Printing Inks and Varnishes

•  Food packaging regulations where inks may be involved: •  General Framework Regulation 1935/2004/EC •  Plastics regulation 10/2011/EC •  GMP 2023/2006/EC

•  Company specific claims •  Company “List of Restricted substances” (e.g. soluble azo dyes, heavy metals such as

lead, hexavalent chromium, mercury and cadmium). •  ITX, benzophenone or 4-methylbenzophenone •  Nestle list

•  Common ground in legislations: 10 µg / 6 dm² (6 dm² is the typical packaging area for 1 kg of food) !10 µg/ 1 kg = 10 ppb: rule-of-thumb for the allowable specific migration limit for the different ink compounds. If sufficient toxicological data available, this limit can be higher.

•  ! Define LOW MIGRATION: Swiss Ordinance ? Low odor ? No migration ?


Let’s formulate!

•  Which pigments do you choose ? •  What monomers will you disperse the pigments in ? •  What functional needs does your ink have: adhesion, smell, chemical

resistance, indoor/outdoor, indirect food contact, … •  Choose the right monomers / oligomers! •  At what wavelengths should the inks be cured and how much UV dose

is available in how many steps (lamps, speeds, window) ? ! Which photoinitiators will you need ?

•  What is the surface tension you are aiming at: fire frequency, nozzle plate coating ?

•  Which functioning combinations can be stabilized for 12 to 18 months ?

•  Do you have freedom-to-operate for the chosen combination ?


UV ink and ink compounds

pigment

additives

monomers

photo-initiator


UV ink photoinitiation

•  Theory: match output UV - absorption of photoinitiator

UV-absorption PI PI*

UV-emission

Output +

Reality: Pigment absorption!


LM ink technology


Not free to formulate for LM inks


Migration testing

•  Single sided extraction •  - dependent on the application different simulants can be

used at different temperatures e.g. water, water + acid, water/ethanol mixtures, ethanol, … - identification and/or quantification of extracted compounds


Migration testing

•  Single sided extraction

- dependent on the application different simulants can be used at different temperatures e.g. water, water + acid, water/ethanol mixtures, ethanol, … - identification and/or quantification of extracted compounds


Migration of molecules ?

FOOD

ink

substrate

~ viscosity


How to go for Low Migration in inkjet then?

Highly reactive

monomers

Low tox or diffusion hindered

photoinitiator


Details of formulations

•  Low viscous but highly reactive monomers monomer comprising: •  at least one acrylate group •  at least one other ethylenically unsaturated polymerizable group preferably selected from the group

consisting of: −  a vinylether group, −  an allylether group −  and an allylester group



•  Diffusion-hindered photo-initiators / co-initiators •  Polymeric PI and/or CO-INI

•  multi-functional ! higher probability of reaction •  higher MW ! low migration speed •  dendritic polymeric architecture ! low viscosity



•  Diffusion-hindered photo-initiators / co-initiators •  Polymerizable PI or CO-INI

•  becomes part of the polymeric network ! bonded PI or bonded CO-INI cannot migrate

•  low MW ! very low viscosity, but high migration speed

examples :


Low Migration UV-curable inkjet inks – how ?

•  Purity •  analytical efforts (supplier or ink producer) •  free of solvents, heavy metals, … •  specific note on pigments ! manageable

•  Nature of compounds: e.g. photo-initiators •  selection of low toxicity compounds = possible •  options : polymeric and/or polymerizable

•  Reaction products •  non intentionally added compounds of another level than impurities •  tricky compounds because unknown when formulating

•  Polymerization degree •  Compliant with legislation and guidelines

•  compliant with European Framework Regulation 1935/2004/EC •  compliant with EuPIA, all ink compounds on positive list Swiss Ordinance

•  Swiss Ordinance 817.023.21 •  all materials are TSCA (USA) and REACH compliant •  other


Examples

KHS Polytype Sacmi Bottling lines Print equipm. food containers food pack. equipm. Direct Print DigiCup printer Colora cap


Summary

•  Inkjet printing on packaging = answer to packaging trends •  UV LM inkjet ink formualtion " low viscosity for jetting •  Thereby requires full conceptual development of LM ink concept •  Monomers and photo-initiators need to be LM ink specific designed

for combination of low viscosity and high curing degree •  Dedicated LM ink technology can result in low migration levels •  Highly reactive monomer is key driver to full curing •  Diffusion-hindered PI system key to curing speed (UV LED curing)

and low migration of PI’s


Thanks for listening

UV Inkjet Printing on Food Packaging: State-of-Art...

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