Drent Goebel’s Rob Meij: Solvent-free flexo and gravure printing is a pipe dream
New environmental requirements present opportunities
Europe is preparing even more robust measures to further restrict use and emissions of
volatile solvents. This will have a major impact on printers in the packaging market. At the
same time customers are demanding increasingly higher print quality while runs are
getting shorter. Is there a way forward? There certainly is, believes Drent Goebel’s Rob
Meij. “Time to invest in offset.”
Are packaging, printing and solvents inextricably linked?
“As long as flexo and gravure exist for printing on film, solvents will be used as the basic
constituent of printing inks. Solvents are also used to clean all parts of the press that come into
contact with ink.”
What kind of solvents?
“Ethanol, ethyl acetate, ethoxy propanol and the like come to mind.”
In what quantities?
“Solvents are usually distilled after the wash-down process and the distillate is reused in dilute
form as a cleaning agent and ink thinners. However, on average some fifty to a hundred tonnes of
fresh solvent are purchased annually for each flexo or gravure press.”
Is this a problem?
“No, it doesn’t have to be. Solvents have been established in the foodstuffs packaging industry for
many years. Odour and migration problems are reasonably under control and the use of
solvents, as such, has been accepted.
But issues such as the environment, health and other risks are playing an increasingly important
part in our society, especially now the European Commission is clamping down on the use of
solvents. The European VOC Directive stipulates that a printing works must not emit more than a
certain amount of solvents. It is expected that this type of ruling will be adopted by other
governments elsewhere in the world.”
Why are solvents used in inks?
“When ink is transferred to the film during the printing process, the ink cannot be absorbed and
hence there is hardly any drying process to speak of if no drying additives are used. For solvent-
based inks to be transferred during the printing process, these inks must adhere to smooth
surfaces very readily through the rapid evaporation of the solvents. This is the main reason why
the flexible packaging industry has been adopted en masse solvents in the printing process.
Some of the vapours, however, are released to our surroundings and the atmosphere, and are
hazardous to humans and the environment.”
What are the main requirements a packaging printer needs to comply with?
“The printing plant requires explosion-proofed equipment. Storage of solvents is subject to
restrictive measures. Moreover, because they are harmful to health, their concentration must not
exceed a threshold value. In the event of this threshold being exceeded, the printing works is to
have a system on the premises which converts the hydrocarbons to harmless substances. There
are two ways of achieving this: biologically or by means of post combustion via a process called
afterburning.
Afterburning is the most commonly used system. A problem with it is that on 1 October 2007 the
European VOC Directive is to be made more stringent. This could mean that installed systems no
longer comply as of that date.”
Are there any alternatives?
“If a packaging printer is unable or unwilling to meet the requirements, he can move to other inks:
water-soluble or polymer inks. Although water-based inks can be used, they do result in
unacceptably low print speeds because they dry too slowly. In addition, water-based inks do not
achieve the intensity of colour and gloss that customers expect.
Polymer inks are dried in the printing process through a polymerisation process that is initiated by
UV light or an electron beam. UV inks are usually used in non-food applications in narrow-web
flexo machines. UV inks are not suitable for use in gravure printing.
UV inks would be well suited for flexible food packaging were it not for the fact that these inks
require what are known as ‘photo-initiators’ in order to initiate the polymerisation process. These
initiators are the fly in the ointment for the foodstuffs packaging industry, since they can leave
behind a characteristic odour in the packaging. They might also come into contact with the
contents of the packaging as a result of ink transfer on rewinding after the printing process or due
to migration through the packaging.”
Will UV technology really be denied any chance of developing in the food packaging industry?
“Although there have been positive developments in the field of UV technology, the traditional
users of solvents are wary of using it. They are worried about claims for compensation from the
market.”
Is offset a good alternative?
“Yes. There are offset presses for food and non-food applications. They are very commonly used
with UV (polymerisation) for non-food. In view of the problems with UV in the market for food
packaging, presses fitted with an Electron Beam drying system can be used here. Drent Goebel
can of course supply presses with either type of drying technology.”
In actual fact there is no difference between UV and EB inks, apart from the fact that EB inks can
manage without photo-initiators. The polymerisation process is initiated instantly on being
bombarded with electron beams during the printing process. As a result of this these EB inks are
safe for food packaging. I would like to use this opportunity to clear up a misunderstanding which
may exist: it is not the inks but the photo-initiators that can cause excess odour and adversely
affect the chemical composition of the packaged product.”
What are the benefits for the packaging printer if he invests in an offset press?
“Solvents will no longer be required. This means: no problems with the VOC Directive, no storage
area required for solvents any more, as well as no distillation boilers, washing machines, waste
management, logistics, explosion and/or fire hazards. No excessive odours in the print shop, no
odour in printed packaging materials, no more human or environmental hazards.
The cost savings that can be achieved with it are also significant. If a flexo or gravure printer can
wave goodbye to solvents completely, then just thirty percent of the space currently taken up by
production will be required.
The printer can also save a great deal of money due to the fact that solvents need no longer be
purchased. According to in-house research based on practical examples, a flexo or gravure
printing house can save one euro cent per square metre of printed substrate in solvents.”
[quote]
“According to in-house research based on practical examples, a flexo or gravure printing house
can save one euro cent per square metre of printed substrate in solvents.”
<Picture caption Rob Meij>
Rob Meij, product manager at Drent Goebel.
<Picture Chemie VSOP.jpf>
Two jerry cans of ink wash-up solution and offset plate cleaner are the only chemicals required
for printing with a VSOP press.
<Picture Chemie Diepdruk en flexo: DSC00760.JPG>
Solvent storage for gravure and flexo printing.
<Picture Solvents at press: DSC00744.JPG of DSC00745.JPG of DSC00746.JPG>
Solvents used with a flexo press.
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“A change of thinking is needed”
Printing technologies are inching closer together. The dividing lines between offset, flexo
and gravure are becoming blurred. Markets which for years seemed to belong resolutely
to a given printing system are migrating to others.
“This requires a mental turnaround on the part of printers”, says Drent Goebel’s Rob Meij, who
regularly visits printers all over the world.
“Printers are facing cut throat competition among themselves. Suddenly new players will enter the
field as well. Furthermore, print runs are getting shorter and demands on print quality ever more
stringent. After all, products on the shelf need the appealing packaging to sell. In addition to this,
European regulations on solvent emissions are now being made a great deal more stringent. I
predict that many businesses will be unable to meet these requirements unless they invest
substantially in afterburning equipment and the like. This will involve major capital expenditure in
a market in which the technical potential for innovation is virtually exhausted. My advice is: look
around you at other printing systems such as offset, and prepare to be surprised by all the
capabilities now available.”