Introduction
The elastomer Plates making process involves the direct engraving of the design onto the rubber material. The major distinction between photopolymer plate making and elastomer plate direct engraving is the absence of plate exposure and the washout process for the elastomer plate.
There is not at all a solvent washout process. There are fewer steps required for elastomer plate making leads to higher product quality: less room for errors at the different stages.
The process includes laser engraving, water wash, and drying, that’s it!
A combination of elastomer, which can include both natural or synthetic polymers, are used in flexo printing because they are:
Ø High quality
Ø Long-running
Ø Easier to interchange
Ø Faster to clean
Ø Reduce waste
The Compounds
Rubber has always played an important part in the flexo industry. Going back to the last century, elastomer was mostly used in sleeve form to print background colors in flexible packaging as well as printing on tissue, wallpaper, and other materials for the decorative market.
There are several reasons elastomer did not really make its way into the classic flexible packaging and label markets until recently. Previously, engraved elastomer plates and sleeves were only suitable for line work and relatively coarse line screens up to 85 LPI. This had to do with the limited elastomer compounds and the rudimentary laser technology of the day.
With the parallel development of high-performance elastomers and more advanced laser capabilities, new levels of quality are possible. Current engraving technologies allow for resolutions of 4,000 dpi and higher (i.e. 5,080 dpi in printed electronics applications). Screen values of 200 LPI are used in everyday production throughout the elastomer plate and sleeve producers around the world.
Material Properties
Today’s high-performance elastomers have more to offer than just improved engraving capabilities. Most current elastomer printing forms are made from a compound called EPDM (ethylene propylene diene monomer).
EPDM is a non-polar synthetic rubber compound that is extremely resistant to UV light and ozone. Due to its polarity properties, it also works very well with ketones, esters, and alcohols, which are polar substances, making it a perfect fit for flexographic printing, not only with solvent-based but also with UV and water-based ink systems.
Since EPDM-based printing forms do not swell with current flexo ink systems and are extremely abrasion-resistant, it makes them a good choice in difficult printing environments, such as plastic cups, tubes, and aluminum can printing, corrugated or nonwoven applications.
Surface properties, such as roughness and surface tension, but also compressibility, are designed to neutralize the feeding characteristics, which a lot of times are the cause of halo effects or mottling. The compounds are also optimized to control ink pickup and release, minimizing buildup.
Elastomer Direct Engraved Plates – Benefits
Elastomer printing forms exhibit outstanding ink transfer properties. Using a laser, however, it is possible to influence the surface structure and further optimize ink transfer in line with the relevant application. Fine screen dots, clean vignettes, and high-resolution line and surface structures require excellent modulation and thus a sufficient number of pixels. Consequently, a standard resolution of 5080 dpi has established itself for high-quality elastomer printing forms.
When it comes to economic considerations, elastomer printing sleeves in particular cost far less than photopolymer equivalents.
The resistance of today’s EPDM materials to solvent/water-based and UV inks, together with their high mechanical resistance, ensures long service lives in production. This in turn is reflected in excellent profitability.
Direct laser engraving is suitable for a wide variety of applications. Direct engraving has been well established for many years in conventional flexographic printing, but it has gradually branched out to cover a number of additional applications that offer significant potential.
Offset Coating / Varnishing
In offset printing, spot coatings/ varnishes are increasingly being used to enhance the decoration of packaging. These were predominantly applied using plotted blankets and photopolymer flexographic printing plates in the past, but direct laser engraving is now opening up completely new surface finishing options for offset print products.
The ground elastomer surface results in outstanding transfer and an exceptional gloss level are achieved with both dispersion and UV coatings/varnishes.
Moreover, EPDM flexographic printing Plates exhibit excellent long-term resistance when printing these types of coatings/varnishes. In sophisticated designs, fine details need to be reproduced to create interesting visual and tactile effects.
EPDM printing plates for coating/varnishing are available with both aluminum and high-strength plastic substrates.
In addition to their impressive technical properties, EPDM printing Plates for this kind of surface finishing are available at an extremely attractive price.
Printing Plates and Sleeves
Regardless of whether you print on flexible packaging, labels, or corrugated cardboard
Made by direct laser engraving: chemistry free with up to 5080 dpi resolution.
You acquire a three-dimensional image with variable depths and absolute flexibility when shaping the shoulders. Solids, linework, and halftone can all be reproduced on a single plate.
The elastomer material is unbreakable and user-friendly while the laser image withstands even severe stresses without any changes. The EPDM surface is resistant to UV and ozone. (Laserline EPDM plates)
Laser engraved elastomer printing plates with On-the-dot precision. Laser engraved printing plates ensure maximum printing quality and reliable reproducibility.
Due to the specially adapted elastomer material, the print image remains unchanged throughout its entire life. The frequency of washing intervals has no effect on the image.
Future Business Prospects
Direct Laser Engraving is facing the same issues as any other new technology, such as digital plate making did in the beginning. These issues include slower production speeds, machine and plate availability, initial investment, and so on. Just like in those days, development has to take place in order to accommodate the market needs.
However, over the last three years, a lot of progress has been made. Engraving speeds have already doubled and faster materials are now available.
Let’s look at DLE’s potential in specific markets:
LABEL PRINTING: AS LABEL PRINTERS LEAN MORE AND MORE TOWARD UV INKS, THIS WILL BE ONE OF THE GROWTH SECTORS FOR DLE TECHNOLOGY.
THE SMALLER PLATE SIZES, IN COMBINATION WITH THE MATERIAL PROPERTIES OF THE ELASTOMER PLATES, WILL OFFER QUITE A FEW BENEFITS WHEN IT COMES TO PRINTING LABELS.
FLEXIBLE PACKAGING: WITH INCREASING PRODUCTION SPEEDS, COMPRESSIBLE PLATES THAT DO NOT NEED CUSHION TAPE, COUPLED WITH ALL OF THE OTHER BENEFITS OF ELASTOMER COMPOUNDS, THE FLEXIBLE PACKAGING SECTION OF THE FLEXO MARKET HAS BECOME INCREASINGLY ACCEPTING OF LASER-ENGRAVED ELASTOMER PRINTING FORMS. FASTER PRESS SPEEDS AND LESS “DIRTYING UP” ALLOW FOR MORE PRESS UPTIME, ADDING TO SIGNIFICANT COST SAVINGS.
CORRUGATED PRINTING: PRE-MOUNTED, LASER-ENGRAVED ELASTOMER PLATES WILL RESULT IN AN INCREASE IN PRINT QUALITY FOR CORRUGATED. ELIMINATING REGISTRATION ISSUES AND TIME-CONSUMING MOUNTING PROCESSES WILL ATTRACT CORRUGATED PRINTERS TO DLE. AN INCREASE IN IMAGING SPEEDS MADE POSSIBLE WITH TECHNOLOGICALLY IMPROVED ENGRAVING UNITS WITH DUAL HEADS AND FOUR BEAMS WILL MAKE DLE EVEN MORE APPEALING TO THIS MARKET SECTOR.
SPECIALTY PACKAGING: DRY OFFSET PRINTING (INDIRECT FLEXO) FOR CUPS AND CANS HAS BEEN LACKING PRINT QUALITY DUE TO THE LIMITATIONS OF TRADITIONAL PLATES, LOSING MARKET SHARE TO IML (IN-MOLD LABELING), HEAT TRANSFER, AND DIGITAL. USING DLE IN THIS SEGMENT WILL CERTAINLY BOOST PRINT QUALITY, DUE TO HIGHER INK DENSITIES, HIGHER LINE SCREENS AND SMOOTHER VIGNETTES (THROUGH THE USE OF SUB-SURFACE DOTS IN HIGHLIGHTS). THIS SEGMENT IS A CLASSICAL UV INK APPLICATION WHERE ELASTOMER’S NATURAL MATERIAL PROPERTIES EXCEL
PRINTED ELECTRONICS: AS THIS APPLICATION BECOMES MORE MAINSTREAM, DLE PLATES WILL PLAY A LARGE ROLE. WITH ROTARY SCREENS BEING COSTLY AND LIMITED IN FINE LINE DETAIL, ELASTOMER PLATES CAN PROVIDE A MEDIUM THAT WILL RETAIN THE INTRICACIES WHILE RESISTING THE EFFECTS OF ABRASIVE INKS AND HARSH SOLVENTS.
In Conclusion
To sum up, direct laser engraved flexographic printing Plates are now used in all kinds of sectors. They have quickly made the transition from a niche product to well-established high-end applications.
The benefits of Direct Laser engraving will continue to grow as the technology evolves.
Faster lasers and improved elastomers will further drive printers to the DLE process.
The ecological advantages of DLE, driven by brands and end-users, may also determine how plates and sleeves will be produced.
Although photopolymer flexographic printing plates are the undisputed number one in flexible packaging, direct engraving offers an extremely attractive alternative. Hybrid operations are possible with direct engraving systems. In the other words, both printing plates with conventional plastic substrates and endless printing sleeves can be produced on the same machine.
Screen resolutions are similar to those of photopolymer printing plates. Resolutions of up to 80l/cm can be achieved, depending on the printing method and material used.
About the Author:
Mohammed Abdul Haleem
Email: packagingprinting@consultant.com
With almost 29 years of experience in the printing industry, he offers proactive recommendations, Flexographic Printing machine, Central Impression, Stack, or Narrow web, anilox roll specifications, flexographic printing sleeves, testing, inventory management, flexographic, Lamination Solventless, or solvent-based, training, representation from experience in technical marketing, production, technical service, parts, and supplies.
His experience covers the spectrum of flexographic markets including pre-press, wide web flexible packaging, narrow web, tag & labels, foil, folding cartons, corrugated packaging applications