19 July 2019 Analogue Printing Technologies

Inks entering calmer waters: how the sector is finding its feet after turbulent times

Printing ink producers have been hit by shortages, banned substances and most recently explosions. They have been sent back to the drawing board to create new formulations and these are now coming to market.

The last 12 months have been tumultuous for ink producers. They have had to cope with a shortage of photo initiators after Chinese authorities began taking action against suppliers by closing them down; they have had changes to the Reach regulations in Europe which has meant that some lower volume chemical components used in ink are no longer available and more recently an explosion in Tianjin has put more chemical suppliers out of action and restricted the supply of some pigments and photo initiators. And this all adds up to price increases and reformulations for inks, particularly LED UV inks.

These already face issues because the range of photo initiators responsive to the narrow wavelength generated by the LEDs is restricted. And 13 of the photoinitiators that ink chemists have had in their kitchen of ingredients are no longer on the Eupia list of approved compounds. Not all were relevant to LED UV inks, as broad spectrum UV has also been hit, but the limited choice of photo initiators has been tightened still further.

Not surprisingly the forced change in ink recipes has created problems for printers, and not just because of increased prices. These have increased threefold in the last six months and further rises cannot be ruled out. Meanwhile, the same apparent ink starts to behave differently on press, ink/water balance goes out of kilter, press speeds must be brought down if fewer photo initiators leads to longer dwell times to ensure a complete cure.

Ink makers have not be standing by. Instead overtime has been cancelled as they scramble to first match the performance of the inks as they stood pre-Reach, and then to push forwards with better inks. Sun Chemical reckons it has done this with SunWave Lumina. The range of inks is built on “a highly engineered UV resin system and provides an exceptionally fast and hard curing under UV LED and low energy mercury lamps”. It will work on both single-sided and perfecting presses.

The ink has undergone extensive testing, including at sites in the UK. It is a four-colour set only at this point, but this is only the starting point in development. “There has been a long thorough development to put a system that performs exceptionally well in offset press. Compared to other systems, there is a very fast cure speed, exceptional ink/water balance; hence it performs very well on press,” says Jonathan Sexton, marketing manager, Energy Curing Products Europe.

It will work with any UV suitable plate with baking recommended for long runs. Sun has its own matched founts and recommendations for third-party founts. “It has been thoroughly tested on the press we have in the Eurolab development centre at Karstein before going to field trials.

“It is a four-colour-only set now, but we are working on a new colour matching system in time for Labelexpo. There will also be a low migration compliant version that is currently being validated.” There are also varnishes under development. For the moment this is being tested, but outside the UK. It delivers a good curing performance with low yellowing characteristics. “We have a litho applied LED varnish and a flexo LE varnish,” he adds. “Komori led the way with LE printing, now the shift towards LED is happening and the future growth of UV in commercial printing is towards LED.

“Coatings remain a difficult area, which means that a press might use LED to cure the colours and mercury lamps for the coatings as can happen in packaging. It’s about finding the most cost effective technology solution.”

Sun shifted production of energy cured inks from St Mary Cray in Kent to Frankfurt last year while low migration inks require a separate plant and are made in Zandaam near Brussels.

Sun Chemical is far from alone. Toyo, its Japanese rival (Sun is owned by Dainippon Ink & Chemicals), is increasing facilities at the Arets business in Belgium. Its reformulations are due to reach the market around now. It will be a four-colour-only ink suited to LED UV and will match the ink that was on the market ahead of the reclassifications a year ago.

“We are using new photo initiators in a new series of inks that are much more stable on press in terms of ink/water balance, which printers have been struggling with,” says a spokesman. “The work is now finished so we can launch the new ink set that is as stable as the ink we had a year ago, perhaps eliminating the few problems we used to have.”

It has had to make similar changes with varnishes, but these have not generated problems to the same degree. At the first step the new ink set will be process colours only, additional colours will follow.

Flint reckons that long standing partnerships with suppliers have helped iron out materials shortages, but this has not been enough to leave it unaffected by the tighter conditions and prices have increased. The Tianjin explosion caused 78 deaths, injuring hundreds more and had led to factory closures while the authorities investigate the cause.

With supply chains already tight, there have been shortages of some photo initiators and red and yellow pigments in particular.

Peter Tresadern, INX International, says that there have been other explosions at plants elsewhere in Jiangsu Province in March and April which “has led to a hardening of the Chinese government’s position towards chemical companies. In this province there are currently some 5,000 chemical manufacturing companies but the Chinese government intends to reduce this to 2,000 by the end of 2020 and to 1,000 by 2022.  This will further squeeze supply.

“Already, since the explosion, we have had 50% increase of the price for one of our pigments. In the past two years red pigment prices have increased between 20% and 77% depending upon the grade, yellow by about 13%. These are expected to rise by at least as much going forward.”

Europe’s largest ink maker Huber has also been scrabbling to comply with the latest regulations and with the photo initiator shortage. It had been using four photo initiators which are no longer available to ink chemists, leading to reformulations and lack of consistency as the inks have been tweaked to improve them and return them to the same consistency as previously.

The reformulated LED UV ink “is at the same technical level as the previous formulation,” says product manager for UV Offset Roland Schröder. “But we know that improvement is necessary.” The project to deliver this has started he adds. “In the short term we will be able to provide the market with a new and improved ink series.

“Each disaster is an opportunity for a new start, so the new ink set will be updated in terms of press performance and handling, and of course compliant with the latest Eupia rulings. They will be suitable for alcohol-free printing.”

The company has settled on the photo initiators it wants to use, both for LED and for low migration UV inks in packaging. “So far feedback from customers has been very positive,” says Schröder.

It includes a spot colour matching system, white and metallic inks. It also includes a bench top piece of equipment which can assess the level of cure. It is aimed first at standard mercury lamp users. The accurate data provided will allow printers to reduce the power of the lamps to extend their life, will give customers a measure of proof that their packaging has been fully cured and enable printers to run presses faster with confidence.

Software analyses the sheet prior to plate making to identify the most difficult areas for curing. This portion of the sheet is cut out and tested with a dissolving compound. Five minutes later this is introduced to the device, which measures the effectiveness of the cure and delivers a pass or fail verdict. This is the information needed to adjust press speed or lamp power. Huber hopes that the New V Cure becomes a standard tool for UV printers, particularly carton printers.

Siegwerk’s LED UV inks are not generally available in the UK where the company is known for its liquid inks. It started work on a new LED UV ink set with the aim of making the inks fully de-inkable two years ago, ahead of the forced changes. UV print has traditionally been considered difficult to recycle and scores poorly on the Ingede test. So too does print with a water based coating, Thomas Glaser, head of technology sheetfed at Siegwerk points out.

Two years ago it began working with StoraEnso on a UV cured ink that could be recycled. “We learned a lot about what we needed to do to get a good drinkable LED UV ink,” he says.

Under the Ingede system a conventional ink will score 301 in terms of particles left in the sheet of recycled material. “In the eight tests we did last year, the maximum score was 159 and the minimum was 23. We scored 93/100 on the trial which indicates good deinkability, a standard LED UV ink scored 70/100 so failed the test.”

Siegwerk had taken a punt on which photo initiators would be outlawed two years before the ban came into place. It was right, excluding compounds that have been placed on the black list.

“When we made the switch, customers asked for their old ink back. We are not 100% there yet, but we are now getting close and customers are now satisfied. Still we are always improving.”

By Gareth Ward

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