A fresh approach

18 February 2011



Strong performance, productivity, price, and environmental characteristics are claimed for melamine-based barrier coatings for packaging.


With the current global focus on sustainability and waste management, barrier-coated flexible packaging - both metallised and clear - is a much-favoured choice among brand owners and retailers today, particularly for liquids and foods. According to Pira International, barrier-coated packaging is forecast to grow at 4.6% annually to 2014, with food and beverage the largest market sector and one of the markets with the best development prospects.

There are several barrier coating options currently available, including AlOx, SiOx, carbon, and epoxy. However, a recent Pira study tipped development of melamine coatings as having the potential to ‘bring a major breakthrough in transparent polymer barrier films for food and pharmaceutical packaging’.

Melamine-based Freshure coatings, a proprietary technology developed by DSM and licensed by its Knowfort Technologies subsidiary, are said to have developed a strong following in the three years since they were launched.

DSM-Knowfort’s patented Freshure coatings, produced using the company’s Symphase technology, are claimed to tick a number of boxes in a packaging buyer’s wish list for barrier coatings. They are said to offer effective barrier properties at low cost for flexible packaging applications, delivering a transparent, impermeable coating via the vapour deposition of melamine on clear or metallised substrates. Melamine is inexpensive, environmentally-friendly, fully recyclable, biodegradable, and FDA-approved for direct food contact. In addition, there is a plentiful supply of melamine, unlike many raw materials in use today.

Freshure coatings can be deposited in two ways, depending on the application. To deliver a functional, transparent gas barrier only, a Freshure-Single Coat can be used. Alternatively, to improve barrier surface tension and add barrier functionality, a Freshure-Top Coat can be applied in conjunction with an Al or AlOx clear barrier.

The Symphase vacuum production process, which uses supramolecular chemistry, is very flexible and consumes relatively little energy, making it suitable for sustainable manufacturing. Under moderate vacuum conditions and above its low sublimation temperature of 200°C, melamine can cover a large surface area in a fraction of a second, creating a thin, <100nm, layer of transparent crystalline coating with very high gas barrier properties.

DSM has collaborated with roll-to-roll coating equipment supplier Applied Materials to implement the Symphase process on Applied’s industry-proven TopMet Clear vacuum metallising system. This enables metallisation on a wide range of substrates, including biodegradable films and OPP, with the application of additional barrier layers. Applications include: combining standard metallisation with Freshure-Single Coat for improved barrier properties; Al metallisation and Freshure-Top Coat for barrier properties and improved consistency of surface tension; or a combination of AlOx Clear Barrier – an inorganic layer that offers barrier properties and improved mechanical stability – and organic Freshure-Top Coat for optimal barrier performance.

Conversion of metallised films with Freshure barrier coatings to packaging is also said to be less complex than with many metallised films. There is no need for inline corona treatment prior to conversion, and Freshure-Top Coat is instantly printable. This is a key feature of the coatings, because other metallised films often require the offline application of print primers. In addition to being time consuming, this can damage the oxide/metallised layer.

With Freshure -Top Coat, it is claimed that there is no reduction in metallic gloss levels, and no added time or cost introduced by extra production steps.

Freshure coatings are said to be less brittle than inorganic coatings, and do not fail at high temperature or humidity. ‘They can extend the shelf life of metallised films from the standard 60 days to 6-12 months and even longer, adding real value for the converter of flexible packaging films,’ states DSM-Knowfort.

Freshure coatings have already ‘built a solid reputation for quality and performance’ in the food and beverage market, where barrier-coated flexible packaging is favoured. However, DSM-Knowfort says there is considerable interest in extending the use of the coatings into other segments of the packaging market, ‘since they are not only totally environmentally benign, but also unhampered by the cost pressures that attend metallising today’.

These additional market segments include pharmaceuticals and medical disposables, which could benefit from the ‘exceptional combination of performance, environmental benefits and easy conversion’ of Freshure coatings. DSM-Knowfort is also exploring the opportunities for Freshure on both multi and monolayer PET bottles, where they can offer improved aesthetics over alternative barrier coatings, as well as full recyclability.

DSM-Knowfort is actively engaged in licensing Freshure coatings for all kinds of packaging applications.


Freshure promises better barrier performance for products such as coffee. Freshure

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DSM-Knowfort

Freshure Freshure


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