Packaging Inks, “Eco Credentials” and Sustainability

Is using Natural Raw Materials the only sustainable option?

While words such as natural and raw are commonly used terms in marketing, these terms only dictate the source of the material and don't necessarily convey the impact of utilising that material for our own needs. For example, crude oil is considered a raw, natural resource, but it is now widely understood that human use of crude oil is contributing to a climate emergency. In using natural raw materials, we need to consider that the provenance of the feedstock is not detrimental to the environment, wildlife or food production and that it is a renewable resource with continuity of availability.

From a production viewpoint, the resultant products must also function as well as synthetic technologies and be commercially viable to ensure fast adoption by end users. Therefore, while a natural raw material might sound like a sustainability goal, the true goal would be achieving a non-detrimental, renewable and natural raw material with excellent function and processability to a commercial product - a much harder task that our partners are taking on.

Figure 1: Natural raw materials might sound good from a marketing point of view, but there are more considerations that should be taken into account.

Renewable options for Inks and Coatings

Bio-based Waxes

Munzing Chemie have been aiming to develop products that include as much renewable or bio-content as possible for several years now. Some raw material technologies would, at first sight, lend themselves very well to this objective. Micronized waxes and wax dispersions are one such technology, especially given the options for natural waxes that are already available. However, for ink applications, waxes often need to be multifunctional and impart one, or more, of the following key properties:

• Abrasion resistance
• Scratch resistance
• Blocking resistance
• Slip
• Matting
• Haptic properties
• Hydrophobicity
• Barrier properties (to water and oxygen)
• Oil and grease resistance

Unfortunately, not all natural wax types lend themselves easily to micronisation or offer the characteristics required to be useful. Therefore, the key lies in the prudent choice of raw material and the skill in the onward processing.

Recent product developments such as Ceretan MBP20220 (100% bio-based micronized wax) and Wukonil NAT1000 (natural wax dispersion) from Munzing Chemie are allowing formulators to adopt bio-based additives without any performance sacrifices.

Sustainably sourced Defoamers

Defoamers have long been based on feedstocks such as sustainably sourced vegetable oils for example. However, defoamers are often complex mixtures and the use of synthetic, raw materials is often unavoidable. Products such as Agitan 109 and Agitan 361 are examples where the renewable content is above 50%. Realistically though, flexo printing lines are severe environments for water-based products, especially as the ink recirculation can cause rapid emulsification and defoamer droplet size reduction. For the moment, polysiloxane defoamers such as Agitan 786N, Agitan 784 and Agitan 761 still rule supreme. Undoubtedly bio-based alternatives will evolve with time.

Renewable Thickeners

When considering more sustainable raw materials, polyurethane-based technologies may not immediately come to mind. It might be interesting to the reader to know that recent developments in Munzing Chemie’s Tafigel PU thickener range have given rise to thickeners with a high renewable content. Tafigel PUR82R is an associative thickener with a Newtonian profile and has a renewable content of 89%, as does the pseudoplastic Tafigel PUR54R. In moving to more renewable feedstock content, both products have a wider regulatory food contact compliance compared to conventional PU-based associative thickeners.

New Bio-Based Technologies 

Recent years have also seen the commercialization of new bio-based materials which have not been traditionally used in the ink and packaging coatings sectors. A great example is Valida, a multifunctional fibrillated cellulose product range from our partner Sappi.

Fibrillated cellulose takes cellulose, sourced from Sappi's own sustainably managed forests, and engineers it back to the primary fibrils making up the cellulose fibres which can form a network via entanglement and hydrogen bonding. These are delivered as waterborne gels and pastes depending on the fibre content.

Valida products have interesting, multifunctional properties that are of interest to the inks and coatings sector including as a pigment and filler stabiliser. The 3-dimensional network of fibres traps and stabilises pigments and fillers against syneresis without affecting key rheological properties required for application purposes. Since many ink manufacturers produce their own pigment concentrates, this is a useful material for the toolbox.

Valida, to the surprise of many, is also a film-forming material.  When combined with other waterborne resins, it can improve barrier properties such as oxygen barrier, and water vapour barrier while simultaneously increasing oil and grease resistance. These properties are finding greater use to meet the increasing demand for coated paper and board to replace plastic packaging.

Figure 2: Sappi have their own forest that they sustainably manage and upkeep. This minimises the environmental impact of their products by allowing them to replace the bioresources used.

What Else Apart from Natural Raw Materials Can Be Considered?

Recovered Carbon Black for a more Circular Economy

As mentioned earlier, naturally derived bio-based materials that are sustainable and non-detrimental may not always be possible. Therefore, under the umbrella term “sustainable”, we might consider materials manufactured from recycled feedstocks. These have the advantage of lowering the amount of waste ending up in landfill and can contribute to a more circular economy, often heralded as a solution to not only climate change, but also biodiversity loss, waste and pollution. 

For example, there has been the emergence of recovered carbon black (rCB) pigment as an eco-friendly alternative to virgin carbon black. The UK based company, Waverly Carbon has been developing and refining the pryolysis of end-of-life tyres, which has resulted in their Emerald rCB range of carbon black pigments available as powder and pellets. While some high gloss inks and coatings might notice a slight difference in optical performance, many applications can make the switch from virgin to recovered carbon black with minimal formulation changes. Some applications even find rCB to have advantages formulation effects.

That being said, the carbon footprint of Emerald rCB is about 500kg of CO2 per tonne, compared to approximately 3000kg per tonne for virgin carbon black. Therefore, relatively small addition levels give a significant contribution to carbon footprint reduction. The production of virgin carbon black results in the formation of polycyclic aromatic hydrocarbons (PAH). Though these levels are typically low, PAHs are nonetheless detrimental to human health and the potential for migration into foodstuffs is wholly undesirable. Typical total PAH levels in Emerald rCB is in the region of 1ppm.

Figure 3: Carbon Black is commonly used for its black pigmentation properties, however, virgin carbon black has a high carbon footprint. Recovered carbon black is produced from end-of-life truck tyres which lowers the carbon footprint and contributes to a more circular economy.

Summary

The products discussed above are far from being an exhaustive list of possibilities for your formulating toolbox and we welcome your enquiries so we can assist you on an individual basis to help you achieve your product development objectives. Our team of technical experts can advise on a broad range of products and applications.