Coating & Laminating Coating: From thin film packaging

to solar reflective films By Tom Kerchiss of RK Print Coat Instruments

laptops, tablets, automotive and aeronautical components,

technology to use for a given application depends to a large degree on the product and the end use requirements of the coating. Coatings may be chosen for aesthetic


reasons, but more often than not the performance features, the degree of enhanced functionality that a coating provides is the main reason why one material may be chosen over another. Of course other determinants need to be

factored in when deciding upon the coating and the technology to employ in applying the coating. The conditions under which the product will be manufactured and used; the potential robustness of the coating solution over the anticipated life of the end product, the economics - the costs involved and any environmental implications are all up for consideration.


The cost element in itself can pose problems in that it can be difficult to quantify. The only certainty when it comes to developing and bringing a product to market is that ‘uncertainty’ is certain. Bringing products to fruition takes time, always in short time. It also has a tendency to introduce processing transients, which in turn can result in excess material waste, etc. The need to reduce waste, an enemy of profit has almost become a manufacturing mantra. Controlling costs without compromising on product performance has encouraged industries to experiment and to look at different ways of doing things. Down gauging, going thin, especially

with regard to filmic and/or laminated structures tends to be associated in the mind of many a packaging professional and converter with packaging grades of material. One however only has to look around to see that manufacturers across many industries have turned to replacing heavier gauge components and materials with thinner materials. Boxboard, flat screen televisions, LCD displays, mobile phones,

32 July/ August 2019

he most appropriate coating

fuel cells and batteries, electronic components and everyday household consumer items have got lighter and thinner in some way. With rising energy costs, the realisation that the Earth’s resources aren’t limitless and the cost associated with process waste and end of life disposal means that the move to thinner products and thinner roll to roll and roll to sheet products, consumables, inks, coatings, etc, is not going to go away. In fact, the ability to coat thinner and implement manufacture on the micro scale using nano-components is still in its infancy. Running thinner webs can be challenging. Substrate or coating gauge band variations; machine rollers that become misaligned can result in coating voids and wrinkles. Thinner webs are more prone to be less uniform and can be affected by heat, moisture and solvents, which can lead to problems during processes such as drying, curing, coating and laminating. Thinner materials or layers of thinner

materials do provide many performance advantages. Increased functionality, for example keypads and computers, that are manufactured using state of the art flexible materials and membranes that can be rolled up, confer obvious advantages, for example polymer semi-conductors. These are made from synthetic polymers and are generally referred to as conjugated polymers. They change from being an insulator to a semi- conductor after being doped. Polymer or plasticised semi-conductors

do not have to be manufactured via the laborious and time-consuming photo masking process and are categorised by many in the industry as being printed electronics with coating being an important process. They are active elements in semi conductive ultra-thin devices such as OLEDs, organic light emitting diodes, etc. Thermal adhesive strips, anti-static layers and hard coats are other areas associated with electronics that benefit from the deposition of thin coating flows, films, etc. Coaters and coating materials are used in

a variety of optical applications for window films and for the deposition of adhesives. Thin films for solar control applications are

set to become one of the most important areas of growth for specialty films and for coated products. Growth is being driven by the need to reduce reliance on fossil fuels and electricity for heating in the home/office and to reduce the need to use air conditioning to some extent in hotels, offices and public buildings. Thin solar films, which can be temperature and light reactive, can be integrated in with window glazing in order to regulate light/glare and heat.

PROCESS LIMITATIONS Many coating lines are designed to operate within reasonable product and process limits. The window of opportunity is limited when it comes to functioning efficiently and delivering thin film and/or specialist products. Coater components, applicator technology and even the coater and other processing technology may need to be evaluated. The new generation of pilot coater, printing and laminating equipment now available together with purpose built to order machines addresses these issues. RK Print Coat Instruments VCM coater is optimised to meet the specific requirements of the customer, the application and end use requirements. This high tech machine incorporates state of the art components and offers a wide range of coating choices, print technology, laminating options, i.e., wet and dry as well as a range of customer selective drying/curing/infrared options. The VCM is being used for a wide range of applications, including those mentioned in this article – solar reflective films, polymer semi-conductors, fuel cells and batteries and printable electronics. Aerospace components, LCD displays, medical diagnostics, security (holograms) and specialist converting and packaging are other product areas that the VCM is currently being used in. A complimentary system, the VCML

LAB/PILOT COATER is available and is ideal for undertaking R and D, quality control, trialling materials/processes, etc. It can print, coat and laminate all types of flexible substrates such as paper, film, metallic foils, etc., and can employ coatings as varied as inks, paints, varnishes, adhesives both solvent and water based on a reel to reel basis. The machine is able to undertake small scale production and it can undertake meter bar coating, slot die, flexo, direct/revers/offset gravure, differential offset gravure as well as rotary screen, knife over roll.

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