TESTING TIME FOR FLEXO INK PRODUCERS
Release Date: September 27, 2007
What would printers like from their ink supplier? They'd like an ink that runs at any speed, that adheres to any substrate, including films, laminates, cartons, corrugated, pressure sensitive materials and non-wovens. They'd like an ink that runs at varying speeds without losing colour strength; one that is weather resistant, heat and humidity resistant and rub, scuff and chemical resistant. Unfortunately, 'universal' ink, one that meets every requirement eludes ink manufacturers. "Although ink chemists do their best to make flexographic inks as versatile as possible," says Tom Kerchiss of sample preparation and colour communication technology specialist RK Print Coat Instruments Ltd.
Standardisation in flexography is one of the key objectives of users and producers of flexo inks - but the fact is that everyone prints under different conditions and for different purposes; consequently a degree of adjustment and customisation is more often than not the norm.
Printers are beset by many problems, some are resolvable on press; some require the assistance of their suppliers. Ink producers and printers must take into account many factors: for instance, a printer may compete for, and land a job that involves printing a product destined to spend long time in a freezer. This necessitates the use of ink that is water resistant. To complicate matters, the product in our example is heat sealed, so therefore the ink must not only be resistant to moisture but must also be heat resistant. In choosing an ink, one of the deciding factors are end use requirements, i.e. high slip, heat resistance, rub resistance, durability, etc.
Inks need to adhere to a wide range of substrates with different surface structures, i.e. porous, non-porous. Some surfaces must be made ink receptive, such as film; but even this is not necessarily straightforward - films for example may have different levels and types of lubricants. Adhesion is one factor; ink producers in developing a new product or new batch of ink must also ensure that the ink meets other performance requirements. These include, colour, viscosity and drying speed. Monitoring performance over time is essential, for adjustment in one area may affect properties in other areas.
And of course consistency of colour is critical. "Visual properties of an ink are a function of the colorant or pigment, in relation to the vehicle system used. They include colour, transparency or opacity and gloss. When we think about colour, we are mostly speaking of hue or shade. The strength or saturation (chroma) of a colour must be taken into consideration, along with how light or dark a colour appears. With certain inks even the size and shape of pigment particles can alter how a colour appears. The amount of pigment used can affect colour strength, while the type of vehicle used influences the hue and value of the ink colour. The colour of the substrate, and drying/absorption properties also impact on final print colour. No wonder ink formulators, pigment producers and other have need of equipment and systems to monitor variables to ensure consistency," states Tom Kerchiss.
Colour communication tools developed for monitoring or developing flexo inks (and UV flexo) such as the FlexiProof from RK Print Coat Instruments is finding favour with ink producers and others. The award-winning FlexiProof 100 and new variant FlexiProof UV enables users to easily simulate 'real world' flexographic print conditions in the laboratory or elsewhere, economically and quickly and without the need to resort to using a full size production press for setting standard tests, for monitoring or for R & D purposes.
Ink manufacturers can monitor how different formulations interact with different substrates to determine the adjustments to chemistry that need to be made. Tests such as durability, flexibility, scratch and wear resistance can be carried out. At the same time regular colour matching samples can be made to ensure colour meets agreed standards, and, without the high levels of waste that would be made using a production press.
The FlexiProof 100 and FlexiProof with integrated UV curing are much more than drawdown devices; both are scaled down but component critically exact versions of flexo production presses. Because these PLC controlled units incorporate ceramic or steel banded anilox rollers and doctor blade, users are able to bring process variables under control off-press in the minimum of time using minimal materials and at low operating costs. "Trialling new products and the carrying out of pilot runs are accomplished more economically using a FlexiProof, which is why both printers and ink makers are using the system," says Tom Kerchiss.
About TMI
Testing Machines Inc. (TMI) manufactures and markets physical property testing instruments for the paper, pulp, film, foil, ink, coatings, nonwoven, textile and corrugated industries. TMI has a network of sales offices and agents throughout the US and in over 50 countries.
The TMI Group of Companies consists of Testing Machines Inc., Delaware, Lawson-Hemphill, Swansea, Ma., Messmer Instruments Ltd., UK, Büchel BV, Netherlands, Adamel Lhomargy SARL, France and TMI Canada.
For Additional Information Contact:
Testing Machines Inc.
40 McCullough Drive, New Castle, DE 19720 USA
Tel: 302-613-5600
Fax: 302-613-5619
E-mail: info@testingmachines.com
Web: www.testingmachines.com
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