SCREEN PRODUCT DECORATION


Fimark specialises in laser marking and decoration of products such as this automotive switch


in many applications and can achieve results that are virtually impossible by any other method, including high gloss metallic, holograms and wood grains. The composition of the foil means that it adheres to a vast range of materials and is protected by a tough lacquer.


One company specialising in this process is Foilco. According to Foilico's David Hornby, the company is getting involved in more and more sophisticated applications including turnkey systems to apply security foils and special effects. Gold blocking is also an option, with hybrid applications on the increase. David explained that where a customer has no printing facility, foiling offers a simple method of achieving a robust print without the need for expensive systems to meet health and safety requirements. Foils comply with the requirements of Reach regulations, EN 71 and heavy metals limit requirements. Furthermore, foil can be laser engraved with codes to identify individual items and their contents. This involves specifying foil that can take the engraving without distortion and this is where technologies combine to serve the needs of the market.


Transfer technology


Allied to foil blocking are heat applied transfers. These are commonly recognised on textiles where both sublimation transfers and pigmented transfers are readily applied to t-shirts and other garments. The more specialised version of these is a surprisingly mundane but very challenging application whereby labels are applied to garments such as overalls that have to survive multiple washes in an industrial laundry. In fact, transfers have most in common with


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Complex designs are possible with lasers, as demonstrated by this glass bottle decorated by Fimark


foil blocking when it comes to those applied to plastics. Here the image is first printed onto a polyester or paper film, with a release layer, then a protective lacquer, then the pigmented image and finally a heat activated adhesive. Some more sophisticated designs may also have gloss metallics incorporated into the image. The transfer is applied to the object using pressure, heat and time.


These transfers are often used on plastic as they bond well to this surface, but other materials such as leather or wood can have transfers applied. The equipment used is similar to a hot foil press where a silicone blanket or die is heated and pressed down onto the transfer. The transfers themselves are either screen printed or gravure printed with any metallic elements created in the same way as foil is produced with deposition.


Think in 3D


While on the subject of transfers, 3-D immersion transfer printing is the process of applying patterns over a range of objects and materials. The image is first printed on a water soluble substrate that is subsequently fed into a water dipping bath. The object to be coated is lowered into the water and the decorated film forms itself around the object to produce an all over effect such as wood grain, carbon fibre or marble. Although this process is normally used for long runs, it can also coat small volumes of standard designs.


In-mould decoration also provides a 3-D option during the injection moulding process. Its use is becoming more viable as carrier films improve and inks can withstand the forces and flows of plastic in the mould. In simple terms a transfer is placed in the mould tool either by hand, with a robot or occasionally on the web. Once the transfer is in position, the mould closes and plastic is injected into the cavity. The big advantage of this system is that the carrier film stays with the moulding and protects the image and the moulding itself.


It is easy to think of product decoration as screen, pad and occasionally digital printing but as this feature demonstrates, there are several other process that can be used to enhance or identify a product. Perhaps the long-awaited increase in manufacturing will reinvigorate these processes, but only if the skills required to operate them are maintained.


Heat transfers can be applied to plastic objects using pressure, heat and time


Tel: 01226 770772 Email: peter.kiddell@pdsinternational.com


March/April 2011 l SCREEN PROCESS AND DIGITAL IMAGING 9


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