GRAND DESIGNS

Inkjet has a lot to offer the décor market, and there are indications its day may have finally come. John Corrall has some thoughts to share

Inkjet is hardly new in the décor market. The ceramic tile market changed over to inkjet almost overnight around the time of the 2008 financial crash. Tough times mean people have to look carefully at their business. The market realised that the economics of inkjet made sense, and suddenly no tile producer could afford to use any other technology. Rotary screen died and inkjet quickly came to dominate.

Now some 12 years later the tile market is very mature, with all production lines long since converted to inkjet. Machine sales into this market are all about replacements or upgrades. Ceramics machine builders are now looking to move into other markets such as packaging, textiles or ‘3D’ ceramics such as tableware.

What about the rest of the décor market?

The key areas inkjet suppliers are targeting are:

• wallpaper

• laminates (e.g. HPL)

• LVT

• edge band

• furniture direct-print

WALLPAPER

This market has real potential. The vast majority of wallpaper is produced on large conventional presses. Set-up times are long, waste is high and a 600mm image repeat distance limits design possibilities. Digitally printed ‘mural’ wallpaper exists, but it is a tiny fraction of the whole, largely limited by the low speeds of the wide format machines used to print it (dominated by HP Latex printers). To capture this market the goal is digital print at full press speeds (60–70m/min). The problems lie in the ink. There are tough EU regulations to meet, a wide range of wallpaper stocks to print and low cost/m² targets. Once these issues are solved there are 300 ‘analogue’ wallpaper production lines to replace, and this might total 1000 including Asia.

LAMINATES

High Pressure laminate is used for furniture, flooring or exterior cladding of buildings. It consists of a sheet of printed paper soaked in resin (melamine) and bonded under heat and pressure to a board. The board may be particle-board, MDF or itself made from multiple layers of

resin-soaked paper. Inkjet is already used to print the paper sheets. Inks may be UK or water-based. A key requirement is that they don’t fade when exposed to heat (e.g. from a hot pan placed on the furniture). Board producers also expect linear print speeds of 50m/minute minimum and print widths around 2.1m (so these are not small machines). Inkjet machine builders in this market are Palis, KBA and Hymmen.

LUXURY VINYL TILE

LVT can look like wood or ceramic tile flooring but is warm underfoot and easier to fit. With any large area of print the human eye will quickly pick out any repeated patterns, so inkjet has a big advantage in that the printed images don’t need to repeat. From this point of view, it can look far more ‘natural’ than conventional print. LVT normally consists of two or more layers of PVC and for durability the print

is on the inside – either on the rear of the clear top layer or on the top surface of the second layer. The main issue is to ensure that the inkjet print does not weaken the bond between the PVC layers. Normally no adhesives are used – the layers are joined using heat and pressure. But normal inkjet inks can act as a barrier and prevent good adhesion between the layers.

EDGE-BAND

While the top surface of say, a table, might have been printed by high pressure laminate (HPL), the edges also need decorating to match. Generally, this is done using ‘edgeband’. Edge-band is most commonly printed ABS [Acrylonitrile Butadiene Styrene] that is then glued to the edge of the board. The edge-band is printed in widths of 300–500mm on a roll to roll system and slit to the required width. Inkjet inks are normally UV type.

After slitting, the cut edge is visible, [so] it is normal to use pre-coloured plastic. For this reason, the inkjet may not be working very hard – typically it may be simply adding a wood-grain pattern on top of light-brown plastic. Colour matching of the edge-band to the rest of the board requires care. Even if the colour match is accurate, differences in gloss level between the top and sides of the board may be unacceptable. Metamerism issues [colours appearing different under different lighting conditions] also arise. So even if the board top and sides have an accurate colour match in daylight conditions, do they still match under LED or fluorescent lighting?

Agfa Graphics is very active in this market. Its PID ink set is low-metamerism and includes additional colours aimed at duplicating ‘wood’ images.

Industrial Inkjet installed its first system for edge-band production back in 2011.

DIRECT TO BOARD

Use of digital print in laminates production opens up the market to much wider design possibilities. But the true goal of any justin-time manufacturing system is always to leave the customisation until the end. Printing onto laminate papers with inkjet doesn’t help much – since the paper must be printed right at the start of the manufacturing process. The decision about what image to print (which must also be matched by the edge band) must be made before board production starts. The ideal then would be to manufacture and stock plain, unprinted boards and decorate them only as required. In other words, the digital print system is printing directly onto an otherwise finished board. The image to print can be chosen at the last moment and can vary continuously to avoid pattern repetition. Again, this is not a new idea. Spanish machine builder Barberan showed their first inkjet system for board printing in 2008. Cefla is another recognised name in this market. Ideally, print systems need to print both the top and sides of the board together and with the same inks – so avoiding

any colour-match or metamerism issues. When printing onto a large area such as a length of kitchen worktop, the accuracy of the board transport system becomes critical. Any errors in the smoothness of the movement will result in visible ‘bands’ in the print.

The next step after printing flat panels is then to print onto 3D furniture, e.g. chairs. While the same issues apply in terms of inks and accuracy of motion, a further difficulty is the limited ink ‘throw’ distance available from the inkjet printheads. With complex 3D shapes –especially concave shapes such as a chair backrest – it is difficult to get the inkjet printheads close enough to the surface to be printed. Inevitably some compromise is needed between using small ink drops for high print quality and larger ink drops which will ‘fly’ further.

Inkjet technology has already made inroads into the décor market, increasing design possibilities and reducing economic batch sizes. Arguably late-stage customisation by direct-to-board printing will take this to another level.