The need to deposit viscous materials as coatings on variable and irregular substrate surfaces is a feature of many different industrial processes. Application of paint to objects and buildings, printing inks to paper and plastic media, sugar glazes to food products, and corrosion resistant layers to aircraft, ships and architectural structures are just a few examples. Working with such viscous materials in this manner is difficult, not just in creating sufficient pressure to force the liquid through an orifice (such as a nozzle) but in obtaining a clear-cut edge at the beginning and end of the coated area.
The conventional approach has been to alter the rheological characteristics of the applied material through the addition of thinning agents and modifiers so that the material is rendered temporarily fluid by heat or shear. This has allowed the continued use of standard application hardware, which can only handle a limited, low viscosity range, as new coating materials are developed.. The problem with this approach, however, is that these rheology modifying and thinning agents are inevitably volatile organic compounds (VOCs) whose use is now being progressively restricted and prohibited for sustainable environmental reasons.
A UK technology development company has applied its extensive experience in the development and commercialization of droplet ejection and deposition technologies to this problem. It has developed a non-contact coating system and hardware that can work with highly viscous liquids such as paints, inks and other coatings with viscosities up to 10 to the power of 7 mPas without the need for reformulation. There are other emergent droplet ejection technologies but these work in a very narrow viscosity range and are generally slow. This system is very flexible and has been designed for high throughput and large scale. In short, it is the future proof solution for the coating industry.
Particular advantages include:
• Materials don’t have to be reformulated;
• Non-contact and long throw distance enable working with rough and 3D curved objects;
• The hardware is configurable for a wide range of different viscosities and different coating thicknesses of tens to hundreds of microns.
The pictures depict a lab demonstrator that can be fully customised to various industrial needs within 18 months. Interested parties will be given a weblink to a video depicting the process and the end product.
Partners are sought from manufacturing and fabrication industries that apply coatings to foodstuffs, medical dressings, consumer goods, furniture, architectural structures, marine, automotive and aerospace products. It is intended that such partners will help the development of this technology through commercial agreements with technical assistance to suit their own particular situations.