Looking beyond piano black in automotive

A large white "XXL format" central console demonstrator was the subject of several presentations and was also included among samples displayed at European Plastics News' Decorative Automotive Plastics conference in Frankfurt am Main, Germany, from 30 November to 1 December 2011.

The demonstrator was shown earlier at K2010 and was developed by polycarbonate film supplier Bayer MaterialScience, ink supplier Prll, high-pressure forming machinery producer Niebling and the US company Artificial Muscle (with its Vivitouch tactile response technology). Prll's IMD development manager Hans-Peter Erfurt described the Vivitouch solution as "developed for the gaming industry, but not yet ready for automotive". However, the technology will receive a feasibility study in the "R&D pipeline for automotive applications", Erfurt added.

In his presentation on Prll's Dual-Cure lacquers, Erfurt pointed out that "secret-until-lit" features are more difficult in white, as a black colour behind a white top surface comes through as grey and becomes less sharp through diffusion, as the white is not very opaque.

A 100mm x 500mm Makrofol LM292 film applied to the centre stack requires high positioning accuracy. Printed hidden symbols not only become illuminated by means of integrated capacitive switches. Part of the stack is decorated with a Makrofol HF278 G4 475m film with a Prll Norilux DC-3 formable dual-cure UV-curing lacquer hardcoat, providing high gloss white backlighting as well as a partially coated matt finish.

In a presentation by Dirk Pophusen, functional films development manager at Bayer MS, he referred to another large central console or centre stack, a "black-panel" technology unit, shown by Preh with a glass based demonstrator at IAA 2011 in Frankfurt in September. Here too there is a similar plastic potential as with the white demonstrator, as German automotive supplier Preh already uses 3D film insert moulding (FIM) as one of the various IMD and IML processes.

Preh is, for example, involved with Bosch, B-LA Siebdruck- und Kunststofftechnik and Albea Kunststofftechnik in production of the BMW 7 Series black panel instrument cluster with secret-until-lit features. Bayer MS supplies a Marnot XL GU130 hardcoated matt surfaced film for the FIM parts moulded by Albea.

In a presentation entitled "Beyond piano black", Tim Wright, R&D director at formable hardcoated film producer MacDermid Autotype, said that although black remains a popular colour, his company is working on "making black even blacker", with "some products already in the marketplace".

He said hard coating originally arose as a solution not only to improve scratch resistance, but also to overcome polycarbonate developing a blue tinge over time due to crystallisation. With regard to current concerns about recycling, Wright pointed out that the hardcoat is not thermoplastic, so it can be filtered out from the PC remelt.

A breakthrough came in 2005, when Autoflex XF (Xtraform) film with high formability and fairly high chemical and abrasion resistance was first used on the Mercedes S Class. The part involved 44 different components and was the first major automotive piano black application.

Wright said: "It was a leap of faith by Daimler, but they recognised the potential compared with paint spray and etching."

Piano black decoration has since reached Audi, Ford, Fiat, VW, and GM/Opel models.

However, Wright continued: "Designers grow tired of the same discussion [of piano black]. They are thinking 5-10 years ahead, as I do. I am not clever enough to think of everything, but I want to hear about what is required and make it happen - with passion and energy."

For example: new textured hardcoats used for the Autoflex S film, with low haze through use of micro-replication technology; or overcoming PC film limits such as its needing a post-cure hardcoat to meet automotive standards, and its short life in switch applications. Here, Wright sees potential for HiForm PE in an oriented PET (OPET) film, as it "has good flex life (ten times that of PC), is surprisingly formable as a pre-cured hard material, and is already used in membrane switches".

HiForm PE has been formed to 7mm depth and can handle sharp corner radii. But as it is limited in thermal soaking performance, MacDermid Autotype has a 2012 R&D programme "to make it work in auto interiors", Wright says. One area for OPET in future could be soft touch surfaces, where other soft touch solutions have inadequate chemical resistance.

Although MacDermid Autotype has been coating PMMA for 10 years, Wright said it is very soft at 100°C and has too low birefringence for displays. But he sees potential for Toray Picasus non-metallic lustre film for badges and chrome replacement. Picasus is a multilayer film with layers of different refractive index, so it looks like sputtered or aluminised film. It is also compatible with hard coats such as Xtraform and is formable.

Wright said MacDermid Autotype had offered textured black film 10 years ago, but it was "not really taken up". Now the time is right, Wright says, for areas of text or ones with, for example, bird and leaf designs.

"Texture is the 'new black', for example economic combination of texture with gloss, lenses with textured bezel, textured feature lines or even mirror effects. But industry has not been brave enough yet to take the offer," he said.

In addition, MacDermid Autotype is working to reduce costs on nano replication moth-eye surface film, for interior surfaces, as fingerprints are reflected. It is also working with moulder Schuster on capacitive switches. Antenna integration with FIM "has already been implemented," Wright said, "but there has been no adoption yet, as far as we know, for inductive charging, even though it is used in the domestic environment, such as for electric toothbrushes".

Among many ideas at MacDermid Autotype, there is also one project that has started that is aimed at development of decorated door spar trim with a stroking action to open windows. Door strips with backlighting are also being developed. Looking at these ideas, Wright says: "15 years ago the FIM light bulb turned on for me. Let's make the same thing happen for designers."

Pieter van der Ster is business development manager for Europe and Asia at AkzoNobel Specialty Plastics and he mentioned in his presentation that a soft-feel rose petal tactile effect on laptops is a project close to market introduction. He also showed use of Reflex technology to orientate magnetisable additives in liquid paint coating. More recently, Reflex has been applied with Keballoy magnetic compound from

Barlog Plastics, enabling post-moulding magnetising of the part, followed by coating with liquid paint containing magnetisable particles. Either way, the result is an image formed by the particle orientation being "frozen" into the liquid paint.

He also highlighted a chrome bright film that is transparent to light for backlighting and brushed chrome. In connection with this, Van der Ster stressed: "Our systems are cost down, if there are higher costs, you can forget about it."

Rhl Puromer managing director Ingo Kleba said his company's PuroClear polyurethane withstands car washing better than paint. He went on to describe the crystal clear PuroClear S material that has self-healing properties, saying that people do not mind a scratch "as long as it disappears again after a certain time".

Kleba said there has to be "change management in the way of thinking. Making surfaces harder and harder is out, since any carbon-based material has a limited hardness. Making the surface self-healing is the silver bullet while maintaining all other surface properties".

The PuroClear S principle is based upon elastic behaviour of the molecular network with its combined structure of irreversible chemical bonds and reversible physical hydrogen bonds, so that the latter recover after damage. Kleba said PuroClear S has been proven in KraussMaffei's ColorForm and Engel's Clearmelt systems. The UV-stable coating is already used for real wood veneer coating and provides a 3D effect, along with covering sink marks.

A 2.5mm thick PC/ABS armrest demonstrator has been moulded with a PuroClear S skin with 1.9s moulding cycle time, followed by 40s curing time, giving overall production time of below 60s for the decorated part. PuroClear S can be demoulded up to 1,500 times without using an additional external mould release, Kleba said.

Looking ahead over the next 5-10 years, Kleba said PuroClear S also has potential to be used as a nanoskin in order to provide a durable anti-reflection solution. Work on this project has already started with the Fraunhofer IWM mechanics of materials institute in Freiburg.

But in the nearer term, Rhl Polymer, working with Abatek, has developed a Polyform 3D technology based on PuroClear and Abatek's Polyform keypad technology. The technology is aimed at centre stacks, with gloss and matt surfaces, back-panel lighting, tactile areas, a capacitive joy-stick and an integrated screen window with capacitive or resistive touch action.