Dry-offset print challenges in-mould labels on quality

Major users of plastic pots and tubs, including Unilever, are considering moving away from high-quality, in-mould labelling as new technology improves the results achievable with traditional direct print.

Over the last decade, Unilever has been among the champions of in-mould labelling. This allows very high-quality printing of thin labels which are then incorporated into the container - including curves and corners - during the moulding process.

Now, as laser engraving of plates for the dry-offset process becomes more widely available, the food multinational is, like others, said to be taking another look at direct print. On one estimate, the cost of in-mould can be up to a third higher, even allowing for operator costs in printing.

The need to compete on-shelf with sharper graphics led many food brands to invest in in-mould. But laser plate-engraving now allows images of photographic quality to be produced through dry-offset.

Tub and cup converter Huhtamaki first invested in laser engraving over three years ago, print development manager Terry Dwyer recalls. He says: "In the past, we struggled to get a good print with dry-offset. But the new laser-engraved plates enable us to print soft, fine dots." He adds: "With these new plates and modern inks, you're on to something good."

Huhtamaki prints on conventional plastics including polystyrene and polypropylene, and recently began printing on to biodegradable polylactide (PLA), including dessert pots for Marks & Spencer. The Havant plant supplies plates to group operations around Europe.

Now RPC Bebo in the Netherlands has introduced laser engraving for dry-offset plates. The plant is taking aim at the yellow fats market in particular, and has already produced tubs for Portuguese margarine brand Prado.

Independent imaging expert Alex Myers speculates: "If these technologies had been available, say, six years ago, in-mould labelling would never have established the hold that it has now, since the quality differences with direct print would have been much less."

Quality improvements for print on to round cups and tubs could go even further, thanks to the introduction of a new press from Dutch equipment manufacturer Van Dam Machine. The system uses tapered rollers to compensate for the angle of the container wall, and results in much better print at the top and bottom of the pack, says Myers.