Tailored solutions ensure best fit

Developing coating systems demands an extensive knowledge of customers’ requirements. RK Print Coat Instruments designs bespoke solutions that allow for variables

Industrial innovation in coated products and their subsequent adoption by consumers in recent decades has been due to a variety of factors not least of which has been the ‘globalisation’ of business, increased economic liberalisation and changes in political attitudes from countries that were previously inward looking. The emergence of new powerhouse economies notably China has also had an impact.

All these factors have contributed to the introduction of more economically viable, more environmentally acceptable and a more imaginatively conceived line-up of products and materials – particularly for the global food packaging industry. Although product development is a multi-disciplinary activity involving many players, coating and laminating has played a big part in product development and quality assurance.

Coating is fast moving and often a situation specific field which can make it difficult for product manufacturers, their research and development personnel and their suppliers to be knowledgeable across the spectrum of technology. A degree of lateral thinking, closer cooperation with supply chain providers and competent product development/quality monitoring systems and equipment is essential.

Performance limiters

“Customers expect to receive a product that is of a uniform thickness, free from blemishes and with the desired properties and performance characteristics needed for the application,” explains Tom Kerchiss. ”Performance limiters include coating viscosity factors – the thickness or resistance to flow, the co-efficient of friction (COF): slipperiness or skid resistant properties and how it interacts with the substrate. In addition there are variables to contend with such as those that affect drying for example, film thickness of coating or difference in stock such as SSB board (very absorptive) or foil (non-absorptive).”

Substrate properties can be critical, influencing good coating quality and product performance. A defective substrate will cause yield loss and cannot be corrected by any additional processes in the coating line. Substrates must have good planarity and not curl otherwise damage will occur in the coating applicator or in the dryer. They should also have straight sides and be free from telescoping. The coating solution is of course important: mixing time and temperature profiles must be right. The correct raw materials must be added at the proper level and at the right points and solution/dispersion properties – percentage solids, pH, particle size and purity – must be within defined parameters.

Other elements to consider include the selection of the correct applicator which is not always immediately obvious, especially when undertaking research and development, contract coating or when asked to print, coat or undertake another process on an unfamiliar or temperamental substrate. Co-polyesters for example, are non-porous and thus impermeable to liquids such as blood, water and bacteria.

Coating uniformity, the desired coat weight and the methods to achieve this are vital for many reasons, one of which is that when it comes to expensive materials no one wants to apply more than is needed. All methods provide an inherent uniformity that they can achieve. If the wrong method is used desired uniformity might not be achievable. Coating is not just a case of deciding whether to employ reverse gravure coating technology or meter bar; every element must function in unison and every component must work synchronously.

For example, unwinding a web at one end of a machine, then drawing a web through the machine so that it can be printed or coated, then winding a web up at the other end for storage and final shipment needs to be considered and undertaken carefully. Rolls must not only be dried and wound with the right degree of hardness, they must look good and be of the right shape and consistency and wound carefully to avoid problems including blocking. The need for highly functional machines that enable users to resolve problems, check quality and perhaps undertake small-scale production is obvious, as is the need for suppliers that offer a high level of support.

Ease of coating technology changeover and modular machine construction has helped make the Rotary Koater a success in world markets. This highly versatile system suits laboratory experimental coating set up as much as it does a more formalised converting production environment.

New product development

According to Kerchiss this system is particularly suitable for operatives engaged in new product development, those with daily changing product requirements. While the Rotary Koater is suitable for many product development and quality control purposes, accepting more than 15 different print/coat head technologies and a variety of drying/curing technologies – no single machine will suit everyone, as production needs constantly change.

“Every organisation has different requirements,” comments Kerchiss. “Within a multi-national company for example, even different departments may have different objectives. The fact that coating is becoming even more complex so that a standard commercially available machine may not have the level of functionality to meet a customer’s specific needs, necessitates a more bespoke approach when providing customers with machines. For this reason we developed the Versatile Converting Machine (VCM).”

Designed and built to tight tolerances using best available components, each system varies in complexity according to the needs of the individual customer. To protect the commercial considerations of customers machines are built in strict confidentiality.

RK Print Coat Instruments

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