Coating and Laminating
requirements. Coatings may be chosen for a variety of reasons, but more often than not, they are chosen for the specific property or properties that the coated materials may provide, such as barrier resistance. A variety of coating techniques and technologies are available for applying adhesives and coatings, but factors such as viscosity/rheology, coating tolerances, film thickness and other performance requirements must be considered. Cost and environmental compliance are important, but much depends on what we want the coating to do. Countless coating formulations are available, including conductive coatings, metallic, filled polymeric and organometallic coatings, as well as acrylic and aqueous materials. Coating often has to be carried out with precision on a broad range of dissimilar materials. Conductive coatings are used for mobile phones and other communicative devices. Coated materials are active elements in semi-conductive ultra-thin devices, such as OLEDs. Thermal adhesive strips, anti-static layers and so-called hard coats are other
Precision coating counts T
By Tom Kerchiss, chairman of RK Print Coat Instruments Ltd
he most appropriate coating technology to use for a given application depends on the product being coated and application
areas associated with electronics that benefit from the deposition of thin coating flows on filmic and other substrates.
While packaging is said to creatively engage the commercial interests and skills of many converters, the need to step out of your comfort zone and process speciality materials becomes ever more inviting. The reason for this is that the materials, the consumables and the resultant finished products can be profitable for the astute and technically adventurous converter.
Speciality materials for speciality goods from the converter’s perspective are often of a short run nature. Converters need to make themselves masters of the quick changeover, which many of them already are. A large percentage of the products that need to be coated are ultra-thin, meaning they can have blemishes and other faults appear more pronounced.
It seems as though almost every manufacturer, regardless of product sector, is striving to reduce the quantity of materials used. Going thin reduces costs, conserves resources and is often done for practical and functional reasons.
Some of these coating and speciality items are now becoming particularly important given climate change. Examples include
the water treatment films, developed for reverse osmosis for filtering and desalination. Other examples include solar controlled films, reactive window materials that are tinted or otherwise coated for the controlled transmission of light, like heat/ glare prevention, in high-rise buildings. Precision defines most coating and adhesive related applications today and, with that in mind, RK has bought out the K 303S Multicoater base unit with fully integrated servo drive and touch screen control. This device is supplied with interchangeable gravure and flexographic print heads and also offers meter bar coating capability.
The K 303S can be used for quality control and colour comparison using various combinations of inks and substrates to determine printability and adhesion. The meter bar coating head expands processing and quality control capability. Bars are available for wet coatings from 4 to 500 microns. The samples obtained are suitable for computer and visual colour matching and for the evaluation of gloss, adhesion and other quality and performance associated requirements. The motor is servo-driven and offers smooth operation at any speed. Servomotors essentially produce torque and velocity based on the supplied voltage and current. In operation the servomotor functions as a closed-loop system. Each proof or sample taken will be within set point. The K 303S is suitable for laboratories, research establishments and converters with multi print processing facilities. With a working web width of 300mm the system enables operators to print, coat and laminate on all types of flexible substrates. Users have access to a wide range of applicator technologies such as slot die, knife-over-roll, flexo, gravure, direct gravure, reverse and offset gravure, and screen, allowing users to select whichever option is the most economical and practical for its function. Drying options include hot air, infrared and UV curing. Zones can be ATEX explosion proof protected and it can be configured for clean room conditions.
18
July/August 2024
www.convertermag.com
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