Technology opens up a colourful future

Large 3D objects can now be decorated with photographic-quality images, using an ink-jet printer, a plastic film and the application of heat and pressure. Pictaflex is a complete wrap-around decoration technology developed by ICI Imagedata, Applied Effects Laboratories - a specialist in decorative technology - and Warwick University. Although full wrap technologies have existed for some time for decorating 2D objects such as mouse mats, 3D technology is still in its infancy. ICI Imagedata has developed a specially coated polyester film. The image is printed onto the film, then transferred to the component under pressure and heat. According to David Pain, Pictaflex product manager: "It is a coating that has the ability to conform and extend to the surface of any 3D object without cracking." Possible applications include interior and exterior automotive trim components, consumer electronics products, sporting goods and aerospace and rail components. "We are currently in talks with a major supplier of automotive interior trim products to develop the technology further for production-scale systems," explained Pain. The process enables any 3D object to be decorated with a full-colour design or photographic quality image by dye diffusion, by bonding it to the surface of the object. The coated polyester film is printed using aqueous inkjet technology. The ink is then fused into the surface of the object by application of heat and pressure in the Pictaflex press. The technology is suitable for large-scale production or individual product personalisation and could revolutionise the decoration of finished parts. Pictaflex has some advantages over existing decoration technologies. As Pain told Eureka: "There are not many alternative technologies for decorating 3D objects. The dominant one at the moment is dip printing or aqua graphics printing, which involves dipping the parts in water tanks." The patented 'DipPrint' water transfer process, from Luscombe and Company, transfers printed patterns to 3D curved surfaces. Transfer is carried out on a static water surface, so the pattern does not stretch or deform. The activator, which is exclusive to the DipPrint process, allows a long working time so the decoration of large parts (panels up to 3m long) is possible. Reject rates are very low, while productivity is high due to a cycle time of around four minutes. Pictaflex could become a genuine alternative to dip printing, says Pain. It offers users a blank canvas for their design ideas. Any digital image can be reproduced on the component, enabling product designers to create their own visuals or use existing imagery. The process can print complex 3D parts and even wraps around angles tighter than 90 degrees. Parts can be printed 'in-register' so that the design can be positioned to match the form of a particular object. Capital investment is low, whether for a stand-alone A3 printing unit - which was launched in June and costs around £3,500 - or for large-scale production. Further development - and a major industry partner - are required before production-scale systems are made available. "We want to get large manufacturers and design engineers interested in the small-scale product first," explained Pain. "Once we've got their juices flowing, we'll look to partner with companies to further develop the technology for large-scale production." Because images can be printed 'on-demand', there is no need to hold costly, printed film stock. Pictaflex also allows parts to be decorated quite late in the manufacturing process. Set-up costs are minimal and no minimum order quantities are necessary, making the process suitable for both short production runs and mass-market volumes. The printing system can decorate a variety of materials - whether plastics, metals, ceramics, glass or wood - using the same hardware, by matching the press setting to the thermal characteristics of the material. Its modular nature allows production line installations to be scaled and configured to meet the changing needs of product throughput and minimal cycle times. Pictaflex presses can be bought in a standard A3 format. Customised industrial presses are made-to-order, designed to meet individual customer requirements for product, size and speed of operation. ICI is actively seeking industrial partners that are interested in developing Pictaflex technology in their specialist markets or geographic territories. Created on computer The first step in the process involves a design - such as a pattern, illustration, text or photograph - being loaded or created on a PC or Mac. "We can do anything that can be printed with an inkjet printer," said Pain. "The process takes two to three minutes per item with the A3 desktop press - but faster times are achievable with industrial systems." Next, he said, the image is sized, reversed and sent to an inkjet printer, adapted to use Pictaflex approved inks, then printed on a sheet of Pictaflex film. Then the part to be decorated is positioned in the Pictaflex Press. "Certain items that can distort when heated - such as thin wall plastics - may need to be supported with a pre-formed mould," he said. Some metals, ceramics or glass may need spraying with Pictaflex lacquer to create a receptive surface. However, many plastic parts made from materials such as PET, nylon, PBT and polycarbonate can be decorated without pre-treatment. The imaged film is then positioned with the printed side of the sheet facing the component. The press is closed and the process begins. A pre-heating phase causes the Pictaflex film to soften and become flexible. At this point, an integral vacuum is initiated and the air surrounding the part is drawn out of the press. This causes the softened Pictaflex film to form around the part. A second burst of heat excites the dye molecules within the printed film, causing them to become mobile and diffuse into the surface of the part. After cooling, they are permanently bonded into its structure. On completion of the heating phase, a cooling cycle is initiated and the film and part are separated. When the part is cool enough to handle, the press is opened and the film and newly decorated part are removed. The part is now fully imaged. The complete cycle time using the A3 press is typically 90-180 seconds, depending on the size and thermal characteristics of the part. The final process depends very much on the specific application. The dyes have entered into the part, so have good resistance to UV and physical abrasion. However, in demanding applications it may be necessary to overcoat the finished part for further protection or to modify the surface finish. "Pictaflex could be adapted to suit any particular company or industry requirement for 3D decoration of parts," said Pain. "We hope to attract partners to help develop the technology further - and perhaps even license the technology to some of these companies."