Traditionally a coating is defined as a material layer applied onto a surface (usually referred to as the substrate) for protection or decoration.
Paints and lacquers are coatings that mostly have dual uses of protecting the substrate and being decorative, although some artists paints are only for decoration. Functional coatings may be applied to change the surface properties of the substrate, such as adhesion, wettability, corrosion resistance, or barrier properties. A major consideration for most coating processes is that the coating will be applied at a controlled thickness, and a number of different processes are in use to achieve this control, ranging from a simple brush for painting a wall, to some very expensive machinery applying coatings in the electronics industry. A number of coating processes are printing processes, many industrial coating processes involve the application of a thin film of functional material to a substrate, such as film, foil, paper or cardboard.
Since 2010, the rapid advancement of the microtechnology has collided with the coatings field resulting in new coatings with novel properties and functions that differ from the traditional ones. Functional coatings consists of organic, inorganic or hybrid materials and can be prepared using a huge amount of techniques depending on the properties of the materials, the substrate and the final application of the coating.
Coatings for NPH (Nutrition, Pharma, Hygiene) packaging applications
In accordance with the EuPIA*/PIJITF**-Definition coatings are not considered of being printing inks:
“Printing inks do not include coatings which are applied with the prime objective of enabling the material or article to achieve a technical function such as heat sealing, barrier, corrosion resistance etc., as opposed to a graphic effect, even though they may be colored.”
This means, that in contrast to inks and varnishes coatings for NPH applications are mainly designed to modify the technical properties of substrates. Therefore, Anti-fog solutions, Heat seal or Barrier coatings could be seen as functional coatings for packaging applications whereas the following products/product groups do not fall under the definition of being a coating: Primers, Release lacquers and Overprint varnishes (e.g. mat, gloss, slip/friction, rub resistance, tactile, 2K).
Similar to printing inks and varnishes, coatings have to be evaluated regarding their suitability for NPH packaging applications and the following parameters must be taken into consideration and assessed for each product and application individually:
- Substrate on which the coating is applied:
Film (e.g. PE, PP, PET, OPA), Foil (Aluminum), Paper, Cardboard etc.
- DFC or non-DFC application
- Existence of an individual coating regulation in the corresponding region
or country where the coating will be launched on the market (if applicable)
- Brand owner requirements (if applicable)
- Application weight
(could range from < 0.3 g/m2 (e.g. anti-fog solution) up to 15 g/m2 (e.g. for special coatings)
(* EuPIA = European Printing Ink Association | ** PIJITF = Packaging Ink Joint Industry Task Force)
Applicable Regulations for Coatings in the EU, USA, China and Mercosur
Some countries around the globe have stipulated individual regulations, both for coatings and printing inks for food contact materials. However, as a joint requirement coatings must equally be compliant to a “Framework Regulation” and follow the “No harm to human health, no adverse effect on the foodstuff”-principle.
The following listing shows an overview about applicable regulations for coatings and the corresponding application:
- There is no separate regulation for coatings available, therefore the “Framework Regulation” (EC) No 1935/2004, Article 3 (No harm to human health, no unacceptable change in the composition of the food, no deterioration in the organoleptic characteristics thereof) must be applied
- The “GMP-Regulation” (EC) No 2023/2006 must be fulfilled
- If a substance is listed in the “Plastic Regulation” (EU) No 10/2011 or the “Swiss Ordinance” Annex 10 or the “German Ink Ordinance” Table 1 with a restriction (e.g. a corresponding SML), this restriction must be met in the final article
Furthermore, there are specific national regulations prevailing EU regulations existing:
- For the Netherlands the Dutch “Warenwet” Chapter X (Coatings) has to be taken into consideration
- For P&B applications a listing in the German BfR Recommendation XXXVI (Paper and board for food contact) should be checked
Relevant chapters of the Code of Federal Regulations, Title 21 (Food and Drugs):
- 21 CFR 110.80 (Current Good manufacturing practice in manufacturing, packing, or holding human food; Processes and controls)
- 21 CFR 175.300 (Indirect Food Additives: Resinous and polymeric coatings)
- 21 CFR 175.320 (Indirect Food Additives: Adhesives and Components of Coatings; Resinous and polymeric coatings for polyolefin films)
- 21 CFR 176.170 (Indirect Food Additives: Paper and Paperboard Components; Components of paper and paperboard in contact with aqueous and fatty foods)
- 21 CFR 176.180 (Indirect Food Additives: Paper and Paperboard Components; Components of paper and paperboard in contact with dry food)
GB 4806.10 (National Food Safety Standard for Paints and Coatings in Contact with Foodstuffs): Annex A (Basic resins allowed to be used in paints and coatings in contact with foodstuffs and relevant use requirements)
GB 9685 (Standard for Uses of Additives in Food Contact Materials and Articles): Table A2 (Approved additives in food contact coating)
GB 30981 (Requirements for content of other hazardous substances in Paints and Coatings): VOC’s, Heavy Metals and other hazardous substances
Specific references for P&B applications:
- GB 4806.8 (National Food Safety Standard for Paper, Paperboard Materials and its Articles for Food Contact)
- GB 9685 (Standard for Uses of Additives in Food Contact Materials and Articles): Table A6 (Approved additives in paper for food contact materials and articles)
- No specific local regulation exist in any of the member states
- For polymeric coatings the principles of the regulations GMC Res. No. 02/12 (updated) and GMC Res. No. 39/19 are applicable