TECHNOLOGY | IML AND IMD


Right: Climate control panel of the Mercedes S-Class produced using IMD/FIM process steps


align the Rama Original tubs to the market bench- mark – the shiny, copper bronze brick. The tub version was successfully upgraded to a metallic- look pack in 2016 and sits comfortably on the shelf alongside the shiny Rama Original brick and consolidates the branding in a consistent way that makes it easier for the Rama consumer to navigate the shopping aisle thereby facilitating an easier shopping mission. Prior to this development, static electricity


proved a major problem that stood in the way of the development of metallic IML labels. During the IML mould entry process static electricity is used to hold the label in place. Because full metallic labels are conductive, they dissipate static charging and this creates instability during injection of the polypropylene. This in turn causes label misalign- ment and product defects. Under normal circum- stances in standard moulds, therefore, metallic labels are not easy to process. Gerhard van Reenen, General Manager at RPC


Astrapak Marcom, says: “In a joint venture between RPC Astrapak Marcom and Verstraete IML, a new label was created via cold-foil printing. The design parameters were amended to ensure that the foiled area did not exceed a specified limit. The solution was a partially foiled in-mould label that means certain areas of the tub are not foiled. To the naked eye, however, the entire tub looks metallic. With this type of technology, static charges remain on the non-metallic part and keep the label stable during the injection process. In addition, this development was achieved using a standard, unmodified mould, which opens the way to metallised IML for a much larger market.” German company Proell manufactures screen and pad printing inks, as well as specialised ink systems and adhesion promoters for in-mould decoration/film insert moulding (IMD/FIM) technol- ogy. Finished decorated components are pro- duced by inserting decorated, formed and trimmed semi-finished film products into the mould during the injection moulding process. For this


18 INJECTION WORLD | June 2019


technology various PC and PBT blended films and hard-coated films as well as a wide range of PC resins for injection moulding can be used. Film insert moulding means that a second surface screen printed film is formed and trimmed, then the film is inserted into the cavity of the tool and back moulded onto the ink directly. The final product is layered – the first surface is the film, intermediate is the ink and finally the injection resin. The decorating ink is protected and sand- wiched by the film material. As well as automotive applications, such as radio and climate control panels, displays, centre stacks and decorative trims, IMD/FIM technology is also used for the produc- tion of covers, displays and housings for smart and mobile phones, laptops, cosmetic packaging and medical devices. Proell adds that producing IMD/FIM optimised moulds is a technologically and economically challenging task. New ink developments, designed as wash-out barriers, protect the decorating inks and permit optimal adhesion to the injection moulding resin. The new flexible Noriphan XWR ink is such a barrier layer, but can also be used as decorating ink for various substrates. It is extremely wash-out resistant and peel tests show excellent values in cohesion in compound. Back moulding trials with conventional moulding tools showed good results concerning wash-out prevention. According to the company, it is of greatest


importance to achieve durable laminate peel strength in the final IMD/FIM product. The individu- al adhesion levels strongly depend on both the material combination and process parameters. Application trials show that bonding is dependent on the decoration ink as well. Most of the decora- tion inks, especially metallic inks, strongly reduce the peel strength values compared to the adhesion to undecorated laminates. But in most cases, peel strength of IMD/FIM parts is significantly higher compared with double sided adhesive tapes used for membrane switches. IMD/FIM constructions with Noriphan HTR lacquer or transparent colour shades


www.injectionworld.com


PHOTO: PROELL


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