Stacy Hoge, Marcom Specialist, Phoseon Technology11.01.14
UV LED curing continues to grow at a rapid pace, with broad usage across digital inkjet printing, adhesives and coatings. As it moves further into the more traditional printing processes of flexographic and screenprinting, the UV LED ecosystem is creating low-migration processes that will enable food packaging to become the next major market that realizes UV LED curing benefits.
What is Low Migration?
“The term ‘low migration’ packaging is commonly used to designate materials used in the packaging structure whose components will not migrate, or move, from the packaging into the product.” (Sun Chemical http://www.sunchemical.com/low-migration-inks-and-coatings/) It is very important to point out that low migration is not about an ink, but about a process. The process includes the following: press, substrates, ink, curing, rollers/screens (in case of flexography/screen respectively), ink film thickness, color print order and max ink deposition.
“To qualify as low migration packaging, compounds contained in the packaging structure, including printing inks, coatings and adhesives, must not have any effect on the appearance, flavor, odor, taste, or any negative effect on the safety of the product contained within the packaging,” Sun Chemical added.
There are two types of migration. First is diffusion migration, where small molecules can easily penetrate into and diffuse across packaging material layers. This can occur even if the printed material has not yet been converted into a food package and filled with food, or later on when the printed package is filled with food and the food starts to “extract” the migrants from the packaging material.
The second is set-off migration, where migrants can migrate from one layer to another, such as a surface printed layer to the non-printed food-contact surface, which is later brought into contact with food. If these are indirect or close contact like in a reel or a stack after printing, set-off migration can occur due to the pressure existing in the reel or stack. During the packaging process, the material must be cured sufficiently before it is rolled into a web or stacked during a screen process, otherwise it might transfer to the non-printed side of a label, which would then become in contact with the food article. (http://www.siegwerk.com/fileadmin/user_upload/images/media_publication/RZ_Know-how_GB_120612.pdf )
Food Packaging Regulations
• EU Regulation 1935/2004: In Europe, the use of UV-cured inks in food packaging is regulated by EC 1935/2004. Regardless of the printing method or curing process, it requires that “food contact materials must not transfer their components into food in quantities that could endanger human health, change food composition in an unacceptable way or deteriorate its taste and odor.”
However, unlike the forthcoming European Union food labeling legislation governing consumer information, there are no mandatory requirements for UV-cured LM printing inks, lamination adhesives, cold-foiling adhesives and lacquers. Instead, there is the Good Manufacturing Practice (GMP), which refers to the consistent control and production of components so they conform to the rules. The European Printing Ink Association (EuPIA), which reviews inks and coatings for legal compliance, is a good source of information on this, as well as the legal requirements.
• Swiss Ordinance: The 2008 revision of the Swiss Ordinance on Materials and Articles in contact with food introduced new provisions for food packaging inks and printed food packaging. Printing inks for food packaging must be formulated only from raw materials covered by the inventory list of the Swiss Ordinance. The packaging inks are regulated in the section 8b of the Ordinance of the FDHA on Materials and Articles (817.023.21): http://www.blv.admin.ch/themen/04678/04887/04891/index.html?lang=en.
Printing inks for food packaging may only be manufactured from the substances set out in annex 1 (Lists I, II and III of plastics) and in annex 6 (lists I - V of packaging inks), subject to the requirements set out therein.
• Migration values of evaluated substances shall not exceed the limits.
• Migration values of non-evaluated substances (Part B of the lists) must be below 10 ppb (0,01 mg/kg).
• Ink and coating production regarding GMP.
The following substances are listed in annex 6:
I. List of binders (monomers).
II. List of dyes and pigments.
III. List of solvents (including the energy curing monomers).
IV. List of additives (without the additives used in the preparation of pigments).
V. List of photoinitiators.
• Nestlé Regulation Description (http://www.giflex.it/Contenuti/1_Guidance%20Note%20on%20Packaging%20Inks%2028-05-2009.pdf): Nestlé provides a document for its vendors and upwards in the packaging value chain (ink makers, coating and overprint varnish manufacturers) that includes the Nestlé Standards on Materials in Contact with Food (GI-80.008) that are mandatory.
The Nestlé Initiative on Packaging Safety and Compliance addresses specifically the ink usage for decoration on packaging materials. The document equally applies to printing inks and varnishes. It specifies with more details the 4 Standards (Outer printing, UV printing, Inner printing and Ink-jet printing). The document aims at guiding further on the assessment of ink and varnish compositions, i.e. information received from packaging vendors via the certificates of compliance (CoC), based on the composition declaration of the ink makers and varnish manufacturers.
UV Curing Technology
The market has seen a steady increase in demand for low migration energy cure systems across all print processes. The growth will be driven by regulations of the printers and brand users – and consumers. Most low migration inks are specifically formulated for traditional mercury based lamps, but as UV LED curing technology goes mainstream, there has been more talk about low migration inks formulated for LED.
Market Adoption of UV LED Curing Technology
In the approximately 10 years since ultraviolet light-emitting diode (UV LED) curing lamps appeared in the market, there have been significant technological advances in LED efficiency and curing lamp performance. The initial challenges have been met and overcome allowing rapid technology adoption across a broad array of industries.
Inks Formulated for UV LED
Ink formulation for LED technology has evolved significantly, and today, there are a growing number of suppliers developing inks that work well with LED technology. As the technology has become more powerful and more compatible inks are available, this has resulted in substantial advanced capabilities for UV printing. Material suppliers have responded to the demand and challenge from the printing world to formulate raw materials that absorb energy corresponding to the wavelength of UV LED light sources.
One of the key ingredients in the chemical formulation is a photoinitiator that serves as a catalyst to initiate the polymerization process when exposed to narrow spectrum UV LED energy.
With the continued widespread acceptance of UV LED systems, availability of suitable base materials continues to grow. The driving factors in advancement of chemistry of raw materials are increased capability and cost effectiveness of commercially available UV LED light sources.
In 2012, more than 20 inks and material vendors touted their support and ability to formulate for LED and more are developed each year. New resins, monomers, oligomers and photo-initiators have been under development. Not only inks, but also coatings and adhesives are now widely available that are either specially formulated for LED or work with both LED and traditional mercury sources. The next step on the horizon is low migration inks for UV LED.
UV LED Benefits
For Low Migration Processes
UV LED technology benefits in conjunction with low migration printing processes makes for an ideal application. LED offers excellent through cure due to the narrow LED wavelength (UVA). It offers more than 20,000 hours of operation with only minimal power drop over time. This process stability is very important to product manufacturers as they can ensure their products are cured consistently run after run without having to worry about bulb degradation. Additionally, UV LED technology provides a uniform output across the print width which again ensures fully cured product.
Here is what companies are saying about low migration inks for UV LED:
Flexography/Screen:
• Flint Group: According to Tom Hammer, product manager, Flint Group Packaging & Narrow Web, North America, Flint Group has been actively promoting UV LED ink technologies. In September 2013, Flint Group Narrow Web won the Award for Innovation at The Label Industry Global Awards in Brussels for its EkoCure UV LED flexo ink technologies. Flint Group was named joint winner alongside co-supplier and development partner, Mark Andy. First launched in the U.S. in 2012, EkoCure inks are now globally available through Flint Group’s extensive distribution network. In 2014, Flint Group Narrow Web North America commercialized many other technologies to compliment the already industry leading innovative products included in the EkoCure brand. Newer products include UV LED Rotary Screen Whites, various UV LED coatings and adhesives, UV Flexo Shrink Whites, to name a few.
• Paragon Inks: Amanda Jones, UK and international sales manager, Paragon Inks, said the company released the latest addition to their portfolio of inks and coatings, the ULM LED range. The ULM LED system meets all the requirements of 10ppb low migration, low odor and low taint. Based on high quality European grade materials, the ULM LED range gives today’s flexo printer a high strength, fast curing with press speeds of up to 180m/min, high performing system for all types of supported and unsupported web printing, from SAL to flexible packaging.
The company works closely with key OEMs, co-suppliers and customers within the web printing industry to bring the market the next generation of energy curable ink and coating systems. It sees UV LED inks and coatings as the next rung in the ladder with regards to technology and the web printing market, bringing the printer and converter not only cost savings but flexibility of converting both supported and unsupported applications.
• Siegwerk: Bernd Miller, head of technology, Business Unit Sheetfed and Narrow Web EMEA, Siegwerk Switzerland AG, said that Siegwerk is currently working to develop LED inks for low migration. They are currently in collaboration to drive the development forward and have some trials in place for late 2014.
Inkjet:
• Agfa: Marc Graindourze, business development manager, Agfa Industrial Inks, reported that Agfa offers the ALTAMIRA Pack of low migration ink sets for full curing with UV LED.
Agfa has developed a full range of low migration inkjet inks for printing on food packaging, not only for printing on labels, but also for printing direct on the primary food packaging (on the non-contact side), which can be a pouch (e.g. polyeolefin, laminate type), aluminum-based sealings, and also direct printing on the food container (both for food and beverages). Most of these printing solutions use UV LEDs for both the pin-curing as well as the final curing, delivering complete curing of the Agfa LM inks, thereby not only resulting in good adhesion etc., but also in low migration according to the legislative guidelines.
• Collins Inkjet Corporation: Kristin Adams, marketing manager, said that it has been Collins Inkjet’s experience that there is a misunderstanding in the printing industry around the term “Low Migration” as it relates to inks. Low Migration defines the selection of packaging materials plus the ink. Regardless of how an ink is formulated, it alone cannot be considered “low migration” until it is applied to a specific substrate. This is why Collins works thoroughly to understand the complete printing process prior to suggesting an ink.
Collins Inkjet does formulate UV and LED low migration inks suitable for food packaging and others. Achieving regulatory compliance is a long process though, and Collins works closely with its customers (end user, integrator, OEM, etc.) to provide an ink solution that meets the desired compliances. Therefore, Collins Inkjet does not have any off-the-shelf low migration inks; they need to be customized to the specific application and substrate in order to be a low migration ink.
• INX: INX has developed offset HUV and LED curable inks. The LED inks meet current low migration standards.
• Nazdar Ink Technologies: Rich Dunklee, global market segment manager – UV inkjet inks, noted that Nazdar has developed low migration inkjet inks that conform to the standard “Nestlé Compliant Inks” standard. This standard is used primarily for printing on thin films used for the packaging industry and printed using inkjet units on narrow web presses. The standard defines a set of ingredients that can be used in the formulation and manufacture of inks. The inks that we have developed use a dual-cure technology that allows them to be pinned using LED lamps and final cured using either a higher power LED or a mercury vapor lamp.
• Tritron GmbH: Janine Hoffmann, director of marketing, reported that Tritron offers low migration UV/UV LED inks.
“Tritron offers a complete low migration ink set called PAX that can be used for product decoration of indirect food packaging and pharmaceutical packaging,” said Hoffmann. “However, materials such as polyethylene or polypropylene require additional measurements in order to comply with migration limits.”
Conclusion
As in other printing markets the UV LED has entered, it becomes a matter of “when,” not “if,” low-migration systems will appear on the market. Large R&D amounts are being spent now to commercialize UV LED low migration inks. And with continuing RoHS regulatory challenges for traditional mercury bulbs looming in 2016, it is imperative for the entire UV LED ecosystem to work together, ensuring a smooth stable transition to a low-migration future.
What is Low Migration?
“The term ‘low migration’ packaging is commonly used to designate materials used in the packaging structure whose components will not migrate, or move, from the packaging into the product.” (Sun Chemical http://www.sunchemical.com/low-migration-inks-and-coatings/) It is very important to point out that low migration is not about an ink, but about a process. The process includes the following: press, substrates, ink, curing, rollers/screens (in case of flexography/screen respectively), ink film thickness, color print order and max ink deposition.
“To qualify as low migration packaging, compounds contained in the packaging structure, including printing inks, coatings and adhesives, must not have any effect on the appearance, flavor, odor, taste, or any negative effect on the safety of the product contained within the packaging,” Sun Chemical added.
There are two types of migration. First is diffusion migration, where small molecules can easily penetrate into and diffuse across packaging material layers. This can occur even if the printed material has not yet been converted into a food package and filled with food, or later on when the printed package is filled with food and the food starts to “extract” the migrants from the packaging material.
The second is set-off migration, where migrants can migrate from one layer to another, such as a surface printed layer to the non-printed food-contact surface, which is later brought into contact with food. If these are indirect or close contact like in a reel or a stack after printing, set-off migration can occur due to the pressure existing in the reel or stack. During the packaging process, the material must be cured sufficiently before it is rolled into a web or stacked during a screen process, otherwise it might transfer to the non-printed side of a label, which would then become in contact with the food article. (http://www.siegwerk.com/fileadmin/user_upload/images/media_publication/RZ_Know-how_GB_120612.pdf )
Food Packaging Regulations
• EU Regulation 1935/2004: In Europe, the use of UV-cured inks in food packaging is regulated by EC 1935/2004. Regardless of the printing method or curing process, it requires that “food contact materials must not transfer their components into food in quantities that could endanger human health, change food composition in an unacceptable way or deteriorate its taste and odor.”
However, unlike the forthcoming European Union food labeling legislation governing consumer information, there are no mandatory requirements for UV-cured LM printing inks, lamination adhesives, cold-foiling adhesives and lacquers. Instead, there is the Good Manufacturing Practice (GMP), which refers to the consistent control and production of components so they conform to the rules. The European Printing Ink Association (EuPIA), which reviews inks and coatings for legal compliance, is a good source of information on this, as well as the legal requirements.
• Swiss Ordinance: The 2008 revision of the Swiss Ordinance on Materials and Articles in contact with food introduced new provisions for food packaging inks and printed food packaging. Printing inks for food packaging must be formulated only from raw materials covered by the inventory list of the Swiss Ordinance. The packaging inks are regulated in the section 8b of the Ordinance of the FDHA on Materials and Articles (817.023.21): http://www.blv.admin.ch/themen/04678/04887/04891/index.html?lang=en.
Printing inks for food packaging may only be manufactured from the substances set out in annex 1 (Lists I, II and III of plastics) and in annex 6 (lists I - V of packaging inks), subject to the requirements set out therein.
• Migration values of evaluated substances shall not exceed the limits.
• Migration values of non-evaluated substances (Part B of the lists) must be below 10 ppb (0,01 mg/kg).
• Ink and coating production regarding GMP.
The following substances are listed in annex 6:
I. List of binders (monomers).
II. List of dyes and pigments.
III. List of solvents (including the energy curing monomers).
IV. List of additives (without the additives used in the preparation of pigments).
V. List of photoinitiators.
• Nestlé Regulation Description (http://www.giflex.it/Contenuti/1_Guidance%20Note%20on%20Packaging%20Inks%2028-05-2009.pdf): Nestlé provides a document for its vendors and upwards in the packaging value chain (ink makers, coating and overprint varnish manufacturers) that includes the Nestlé Standards on Materials in Contact with Food (GI-80.008) that are mandatory.
The Nestlé Initiative on Packaging Safety and Compliance addresses specifically the ink usage for decoration on packaging materials. The document equally applies to printing inks and varnishes. It specifies with more details the 4 Standards (Outer printing, UV printing, Inner printing and Ink-jet printing). The document aims at guiding further on the assessment of ink and varnish compositions, i.e. information received from packaging vendors via the certificates of compliance (CoC), based on the composition declaration of the ink makers and varnish manufacturers.
UV Curing Technology
The market has seen a steady increase in demand for low migration energy cure systems across all print processes. The growth will be driven by regulations of the printers and brand users – and consumers. Most low migration inks are specifically formulated for traditional mercury based lamps, but as UV LED curing technology goes mainstream, there has been more talk about low migration inks formulated for LED.
Market Adoption of UV LED Curing Technology
In the approximately 10 years since ultraviolet light-emitting diode (UV LED) curing lamps appeared in the market, there have been significant technological advances in LED efficiency and curing lamp performance. The initial challenges have been met and overcome allowing rapid technology adoption across a broad array of industries.
Inks Formulated for UV LED
Ink formulation for LED technology has evolved significantly, and today, there are a growing number of suppliers developing inks that work well with LED technology. As the technology has become more powerful and more compatible inks are available, this has resulted in substantial advanced capabilities for UV printing. Material suppliers have responded to the demand and challenge from the printing world to formulate raw materials that absorb energy corresponding to the wavelength of UV LED light sources.
One of the key ingredients in the chemical formulation is a photoinitiator that serves as a catalyst to initiate the polymerization process when exposed to narrow spectrum UV LED energy.
With the continued widespread acceptance of UV LED systems, availability of suitable base materials continues to grow. The driving factors in advancement of chemistry of raw materials are increased capability and cost effectiveness of commercially available UV LED light sources.
In 2012, more than 20 inks and material vendors touted their support and ability to formulate for LED and more are developed each year. New resins, monomers, oligomers and photo-initiators have been under development. Not only inks, but also coatings and adhesives are now widely available that are either specially formulated for LED or work with both LED and traditional mercury sources. The next step on the horizon is low migration inks for UV LED.
UV LED Benefits
For Low Migration Processes
UV LED technology benefits in conjunction with low migration printing processes makes for an ideal application. LED offers excellent through cure due to the narrow LED wavelength (UVA). It offers more than 20,000 hours of operation with only minimal power drop over time. This process stability is very important to product manufacturers as they can ensure their products are cured consistently run after run without having to worry about bulb degradation. Additionally, UV LED technology provides a uniform output across the print width which again ensures fully cured product.
Here is what companies are saying about low migration inks for UV LED:
Flexography/Screen:
• Flint Group: According to Tom Hammer, product manager, Flint Group Packaging & Narrow Web, North America, Flint Group has been actively promoting UV LED ink technologies. In September 2013, Flint Group Narrow Web won the Award for Innovation at The Label Industry Global Awards in Brussels for its EkoCure UV LED flexo ink technologies. Flint Group was named joint winner alongside co-supplier and development partner, Mark Andy. First launched in the U.S. in 2012, EkoCure inks are now globally available through Flint Group’s extensive distribution network. In 2014, Flint Group Narrow Web North America commercialized many other technologies to compliment the already industry leading innovative products included in the EkoCure brand. Newer products include UV LED Rotary Screen Whites, various UV LED coatings and adhesives, UV Flexo Shrink Whites, to name a few.
• Paragon Inks: Amanda Jones, UK and international sales manager, Paragon Inks, said the company released the latest addition to their portfolio of inks and coatings, the ULM LED range. The ULM LED system meets all the requirements of 10ppb low migration, low odor and low taint. Based on high quality European grade materials, the ULM LED range gives today’s flexo printer a high strength, fast curing with press speeds of up to 180m/min, high performing system for all types of supported and unsupported web printing, from SAL to flexible packaging.
The company works closely with key OEMs, co-suppliers and customers within the web printing industry to bring the market the next generation of energy curable ink and coating systems. It sees UV LED inks and coatings as the next rung in the ladder with regards to technology and the web printing market, bringing the printer and converter not only cost savings but flexibility of converting both supported and unsupported applications.
• Siegwerk: Bernd Miller, head of technology, Business Unit Sheetfed and Narrow Web EMEA, Siegwerk Switzerland AG, said that Siegwerk is currently working to develop LED inks for low migration. They are currently in collaboration to drive the development forward and have some trials in place for late 2014.
Inkjet:
• Agfa: Marc Graindourze, business development manager, Agfa Industrial Inks, reported that Agfa offers the ALTAMIRA Pack of low migration ink sets for full curing with UV LED.
Agfa has developed a full range of low migration inkjet inks for printing on food packaging, not only for printing on labels, but also for printing direct on the primary food packaging (on the non-contact side), which can be a pouch (e.g. polyeolefin, laminate type), aluminum-based sealings, and also direct printing on the food container (both for food and beverages). Most of these printing solutions use UV LEDs for both the pin-curing as well as the final curing, delivering complete curing of the Agfa LM inks, thereby not only resulting in good adhesion etc., but also in low migration according to the legislative guidelines.
• Collins Inkjet Corporation: Kristin Adams, marketing manager, said that it has been Collins Inkjet’s experience that there is a misunderstanding in the printing industry around the term “Low Migration” as it relates to inks. Low Migration defines the selection of packaging materials plus the ink. Regardless of how an ink is formulated, it alone cannot be considered “low migration” until it is applied to a specific substrate. This is why Collins works thoroughly to understand the complete printing process prior to suggesting an ink.
Collins Inkjet does formulate UV and LED low migration inks suitable for food packaging and others. Achieving regulatory compliance is a long process though, and Collins works closely with its customers (end user, integrator, OEM, etc.) to provide an ink solution that meets the desired compliances. Therefore, Collins Inkjet does not have any off-the-shelf low migration inks; they need to be customized to the specific application and substrate in order to be a low migration ink.
• INX: INX has developed offset HUV and LED curable inks. The LED inks meet current low migration standards.
• Nazdar Ink Technologies: Rich Dunklee, global market segment manager – UV inkjet inks, noted that Nazdar has developed low migration inkjet inks that conform to the standard “Nestlé Compliant Inks” standard. This standard is used primarily for printing on thin films used for the packaging industry and printed using inkjet units on narrow web presses. The standard defines a set of ingredients that can be used in the formulation and manufacture of inks. The inks that we have developed use a dual-cure technology that allows them to be pinned using LED lamps and final cured using either a higher power LED or a mercury vapor lamp.
• Tritron GmbH: Janine Hoffmann, director of marketing, reported that Tritron offers low migration UV/UV LED inks.
“Tritron offers a complete low migration ink set called PAX that can be used for product decoration of indirect food packaging and pharmaceutical packaging,” said Hoffmann. “However, materials such as polyethylene or polypropylene require additional measurements in order to comply with migration limits.”
Conclusion
As in other printing markets the UV LED has entered, it becomes a matter of “when,” not “if,” low-migration systems will appear on the market. Large R&D amounts are being spent now to commercialize UV LED low migration inks. And with continuing RoHS regulatory challenges for traditional mercury bulbs looming in 2016, it is imperative for the entire UV LED ecosystem to work together, ensuring a smooth stable transition to a low-migration future.