New technologies in product finishes and coatings are being developed in Australia to simplify complex processes, reduce time and costs, and improve environmental outcomes.
One of the major breakthroughs is in the area of powder coating with research facilities in Melbourne focusing on a new generation of powder coatings with low temperature curing.
Trends in electroplating are incorporating environmental requirements with efforts being made to reduce, and perhaps even eliminate, the use of hexavalent chrome. The new applications are looking to trivalent chrome, which does not pose the same health risks.
Plastics are replacing painted finishes as they provide decorative and functional surfaces using in-mould decoration technology and a large range of colour and effect options.
Paints are used in a wide variety of applications. New developments in reducing the solvent (toluene and xylene) content of paints, which can make up to seventy per cent of conventional liquid paint volume, are being conducted worldwide. Toyota, Ford and automotive re-finishers in Melbourne now use water based paint systems for their car body paintwork.
Powder coating is a robust reliable finish used extensively in appliance, automotive, outdoor architectural and industrial applications. Powder coating has been protecting metal products since its inception in the 1950s.
Today’s powders come with a variety of properties and a large palette of colours ensuring a solution to a multitude of projects and applications both internally and externally.
Powder coating is essentially ‘paint without liquid’. There’s little if any volatile organic compounds which means no solvent, water or sludge to manage. This makes recovery of powder ‘overspray’ re-useable, which saves on the amount of material used and reduces environmental impact and waste.
A smooth surface is obtained without solvent bubbling and paint runs, and there is no need for primers and undercoats. Powder coating is a one coat, one process finish.
The popularity of powder coating has increased due to its unique finishing properties. Typically, superior adhesion, impact, scuff and corrosion resistances are obtained from powders compared to liquid based systems. A more controlled and higher coating thickness can be obtained with powder coating.
Powder coating surfaces are sometimes exposed to chemical environments, high operating temperatures or high impact environments. This type of finish is generally used on engine blocks and bull bars on vehicles, heater panels, gas pipelines, washing machine bowls, bathtubs, aluminium extrusions and lighting fixtures.
Due to the historically high curing temperatures (200°C) associated with powder coating, the use of this finish has been limited to ‘heat tolerant’ metal substrates.
High temperature curing is no longer a requirement for the new generation of powder coatings developed by Dulux in their research laboratories in Melbourne.
Low temperature curing of powder coats is now available, which opens the door for alternative finishing of materials previously thought impossible. Heat Sensitive Substrates (HSS) such as medium density fibreboard (MDF), plywood and plastics can now be powder coated with this new technology.
Dulux has developed a range of finishes which can be cured by either combination infra red/convection (Dulux “Trimatrx®”) or infra red/ultra violet radiation (Dulux “Xienta®”).
The process involves preparation of the product to be coated – this can include fabrication, conditioning and hanging. It is then electrostatically sprayed with one coat of the new technology powder coat, before entering a curing zone set at temperatures of approximately 130°C.
Dulux registered HSS Applicators have installed dedicated equipment for finishing of heat sensitive substrates and work closely with Dulux to keep abreast of the rapidly developing technologies becoming available in powder coating.
“With our long history in the powder coating of metal components, it was pleasing to see the emergence of something new and exciting within our industry,” says Ihab Bana, operations manager at Megacoat in Melbourne.
“When Dulux first presented this finish to us we were so impressed with the quality and design flexibility of the surface that we soon decided to commit our resources and invest in the new technology.
“We are almost one year out from start up and more and more manufacturers are selecting this surface with its enormous benefits over the more traditional choices. We are quietly confident that the time is coming when we will see this new process dominate other forms of MDF finishing”, Bana said.
The opportunities these new powder coatings provide to designers and those working with materials such as MDF are extensive. Seamless edges and grooves can be coated and protected with durable powder coatings.
There is no need for edge strips that limit the contours and shapes of items such as workstations, signs or computer tables. And there is an improvement in the speed of process, to the extent that the one coat finish can be applied, cured and stacked in hours, not the days or weeks that alternative finishes such as polyurethane paints require.
The market potential for choice of colours and effects that the new powder coating process brings is enormous. Practically any colour can be formulated including metallics, and finishes such as pearlescents – often used to imitate anodised aluminium – with various colourways, as well as a range of textured effects.
“Over the past four years, Dulux has been developing the technology and an accredited system for powder coating MDF that significantly reduces the risk of issues such as post-cure ‘edge cracking’, peeling and bubbling,” says Gareth Connell, sales development manager, Dulux Powder Coatings.
“As the quality of MDF can be so varied in Australia, we had to re-think our approach to the entire coating process. We researched the myriad of grades available to the industry and came to the conclusion that a specific board was needed for consistent and repeatable results, to ensure a high quality finish was achievable.
“Plant and equipment is very specialised for powder coat finishing of MDF board.
“The coating process, otherwise known as the Trimatrx® System, incorporates the MDF board (developed with Orica Adhesives and Resins and Alpine MDF Industries), the powder coat finish and the registered applicator,” Connell explained.
Electroplating is used extensively for finishes in tapware, plumbing products and jewellery. Trends in electroplating are moving away from bright chromes and leaning towards satin chrome, black satin, and satin pearl.
Environmental requirements are forcing local manufacturers to reduce the amount of hexavalent chrome used. Peter Harrison, Honorary President (Victoria) of the Australasian Institute of Metal Finishing says the change to trivalent chrome is being driven by North America and Europe.
“Vehicles that are being exported into these markets have to reduce the amount of hexavalent chrome used,” he explains.
“Most of the high corrosion resistance was being delivered via zinc plating with hexavalent chrome. Now manufacturers are being pushed to go to trivalent chrome which doesn’t have the health impact that hexavalent does.
“The electroplating industry is working to find trivalent chrome finishes that have high levels of corrosion resistance.”
Automotive design is also moving to soft plastics rather than hard chrome trims, driven by fashion and cost. Automotives are now generally designed to use less metal, making them more lightweight, fuel efficient and more economical to produce, and in some instances safer to drive.
In-mould decoration and plastics
A new product from GE Plastics called LEXAN® SLX is a fine layer of weatherable co-extruded film that offers in-mould decorating (IMD) options for plastic automotive body panels and other surfaces affected by weather.
A polycarbonate-based film, LEXAN® SLX, can be processed using large in-mould decoration techniques on plastic parts and is well suited to a wide range of exterior body panel applications, matching well with a variety of substrates.
It delivers a high quality surface finish in a deep gloss, is scratch and chemical resistant, and has the ability to withstand prolonged exposure to ultraviolet rays without fading.
For automotive manufacturers, the film can eliminate new paint line investment and paint line emissions. Plastic parts can reduce vehicle weight significantly.
Anita Cunningham, marketing manager, for GE Advanced Materials in Australia says tooling needs to be specifically designed for IMD at the outset with much greater emphasis on communications within the IMD supply chain.
“Several partners need to be involved in the process – film and ink suppliers, a resin supplier, toolmaker, film formers and printers (often one and the same) and an injection moulder,” she says. “Although it is an intensive process, if properly designed and resourced, IMD can deliver significant productivity.”
Plastic parts in general, with their colourability and variable surface finishes, are creating economically viable alternatives to metal parts in many product applications such as automotive grilles, fridge panels, notebook covers, memory sticks, calculators, PDAs, monitor screens, automotive door handles and cameras.
“An automotive grille moulded in ABS (a $3 a kilo material) and painted to the cost of $10-$15 a part can be replaced by Geloy® resin (at $10 per kilo) which needs no paint finish. This creates a saving of up to $14 per part,” says Phil Sheridan, automotive platform manager at GE Advanced Materials.
Fiberlok a US based company, is using GE resin to produce a film using Lexan® for IMD and other applications. The film is impregnated with fibres and digitally printed.
The film provides a soft, plush durable surface finish with the look and feel of soft denim, suede or simulated textiles. It can be used in handgrip design for tools and hand held appliances such as PDAs and mobile telephones.