Application of the ePD™ process as a technical alternative to functional decorative chrome plating with chromium (VI) of plastic surfaces

Number

440-EN

Section

General Section

Use

Sector

Other

Function

Plating agent

Process

Treatment of articles by dipping and pouring

Product category

nin-metal-surface treatment products

Application

Decorative chrome plating

Abstract

Chromic acid was added to the REACH authorisation list in 2013 and its use has required authorisation in the EU since 2017. As a technical alternative, an embedded PVD process is used, in which the applied metal layer is enclosed between two UV coating layers. The final coating is REACH compliant and recyclable according to EU directives.

Substituted substances

Chromic acid

CAS No. 7738-94-5 EC No. 231-801-5 Index No.

Chemical group

Chromium compounds; inorganic acids

Other adverse effects

The substance is: 1 carcinogen (IARC: chromium VI compounds), as listed in the Substance Database according to SUBSPORT Screening Criteria (SDSC).

Reliability of information

Evidence of implementation: there is evidence that the solution was implemented and in use at time of publication

Reason substitution

CMR
skin/respiratory sensitizing
other toxic effects
ecotoxicity
physical hazards

Other type of alternative

ePD™ (embedded PVD for Design Parts) Using substance(s): Elemental metals (e.g. elementary chrome oder elementary aluminium) or metal-ceramics and UV-lacquer. Additionally needed as process gases: Argon, nitrogen or acetylene.

Hazard Assessment

a) Human health:
In comparison to the conventional process, the ePD™ technology includes no hazardous substances such as boric acid. Many harmful and toxic substances to human health used in electroplating with chromium such as chromic acid, boric acid or per- and polyfluorinated surfactants can be substituted with the process. As it is a closed system, there is no worker exposure to any substances.

b) Environment:
The complete ePD™ process produces a very low amount of emissions. The PVD process is vacuum based and free of any gaseous or solid waste. Residual target materials can be completely recycled or disposed of as standard metal waste. All UV substances used are registered (no SVHCs) under REACH and none are considered as endocrine disruptors. As an advanced function, a UV lacquer recy-cling unit is implemented in the paint booth and the off-gas system. The off-gas only contains small volumes of VOC, which are below legal limits or can be elimi-nated by post-combustion. Furthermore ePD™-coated parts are recyclable like standard plastic parts. The technology consumes less energy compared to the conventional process.

Description of Substitution

a) Description of procedure or technology (including pre-/post-processing):
ePD™ is a combined technology of UV coatings and the vacuum metallisation in the nanometer range and is developed as alternative to the entire electroplating process including pre-treatment and post-treatment. ePD™ based coatings consist of three layers: a primer, a thin (between 50 and 200 nm) metallic decorative film and a top coat. The primer serves to even out irregularities in the injection moulded plastic substrate. A thin metallic decorative film is applied on the top of the base coat using PVD technology (metallisation in a vacuum). Another paint layer is applied for protection and to ensure the correct gloss level. The process sequence is as follows: Manual or automatic spindle load -> CO2-snow-ice Cleaning -> Application of the UV base coat -> Magnetron sputtering of the metallic or metallic-ceramic thin film -> Application of the UV top coat -> Manual or automatic unloading of the spindle. The entire process time is approx. 50 minutes. The temperature remains below 80°C over all process steps. The metallic look is created by the PVD layer. Beyond the classic chrome colour, ePD™ offers a large variety of colour options, from mirror chrome to darker chrom colour shades (gloss and matt) and many other colours. The ePD™-System can be applied on plastic ABS substrates as well as on many other polymers such as PC, TPE and PA without the etching pre-treatment. The ePD™ process produces very low emissions and uses few resources. EPD™ coated products are recyclable, due to the very thin metal-layer.

b) Way of application e.g. spraying, dipping, open/closed system etc.:
The base coat and the top coat is applied through spray painting. The application of the PVD-layer is carried out by magnetron sputtering deposition technology in a vacuum chamber. This process is a non-thermal vaporization where the surface atoms of the source material are physically ejected from the solid surface by the transfer of momentum from bombarding particles. The process itself is fully automated and takes place in a closed booth/chamber with separate air conduction.

c) Risk management measures (technical, organizational and personal):
Since the ePD™ technology is fully inline, no contact to human beings occurs in the standard process. Therefore, no occupational safety and health protection measures are required. The paint application process follows the regulations for paint- and off-gas equipment.

Advantage or Disadvantage of Alternative

Aspect	Advantage/disadvantage to conventional process
Technical requirements	Corrosion resistance: ePD™ has successfully passed all kinds of corrosion tests (DIN EN ISO 9227 (incl. adhesion test afterwards), VDA 233-102, etc.) in the automotive industry. Particularly winter salts combined with brake-pad dust create severe problems for a plated surface. ePD™ has “unlimited” corrosion resistance (over 1 000 hours CASS test without damage), if inert metals are used in the PVD-layer. The UV topcoat protects the PVD layer additionally but even with mechanical impacts like stone chipping no corrosion occurs. However, with a highly corrosion-resistant surface, the brightness is lower by about 2 to 4 points. Chemical resistance: ePD™ has passed OEM approvals for the automotive sector. Wear resistance: The wear resistance has been approved for the automotive interior, exterior and sanitary industry. Adhesion between coating and substrate: The adhesion of the UV primer is controlled by the resin technology. A physical/chemical adhesion mechanism assures the bondage, and therefore, unlike traditional plating, no adhesion problems occur especially after temperature cycling. Sunlight resistance / UV resistance: The final UV resistance is controlled by the UV topcoat, which is stabilised by a UV-enhanced package. This package prevents the system from long-term degradation or yellowing. The tests are specified on methods required by weathering (Florida, Arizona, and Kalahari exterior test) or accelerated weathering simulations. Temperature resistance: ePD™ is highly resistant to temperature changes from -40°C to +80°C. Ultimately, the temperature resistance depends on the type of plastic. Geometry: ePD™ can be used for all shapes/geometries. The parts can be very small (i.e. design trims, buttons, etc.) up to large parts (1.5 m) i.e. automotive front grills or bumper trims. Restriction for coatings inside: diameter = depth. Radar transparency: The inbound and outbound radar transparency of metallised plastic parts is possible, for example, for safety distance control solutions integrated into the front grills of cars or lane departure warning sensors in the exterior trim. Contact sensors: The integration of capacity sensing technologies in metallised plastic components offer attractive design solutions, such as door handles responding to touch or electronic control panels and sliders. Day/night design: The integration of capacity sensing technologies in metallised plastic components offer attractive design solutions, such as door handles responding to touch or electronic control panels and sliders. Transparent or translucent on closed surfaces: The thin PVD coatings can be made translucent for light sources beneath the coated part. At night and when dark, coated parts – that look metallic during the day – can provide signal lighting or back lighting.
Implementation	Commercially, customers would need to replace their ex-isting chrome plating machines with the new ePD™ technology. The cost of investment for one standard sys-tem INUBIA I with full automation would be slightly high-er to that of investment in chrome plating machines. A single INUBIA I system would suffice to realise the same throughput of parts as a traditional electroplating line. Depending on the geometry or size of the parts, either ePD™ or electroplating is more cost efficient. The anticipated timeline to install ePD™ is estimated to be 18 months for machine assembling, installation and ramp-up.
Operational expenses	Labour costs: Work with the INUBIA I system requires two operators for the machine and a certain amount of workers for loading, unloading, inspection and logistics. This is comparable to conventional metal plating technologies hence it is job neutral. Throughput: The throughput of parts is 1:1 in comparison to electro-plating. Cycle times of 35 seconds per coating unit (spin-dle) are achieved. Material costs: The material costs are the same compared to convention-al metal plating technologies (the very thin PVD-layer is cheaper; the UV lacquer is more expensive). Energy costs: Energy consumption is lower than in electroplating.

Aspect

Advantage/disadvantage to conventional process

Technical requirements

Corrosion resistance:
ePD™ has successfully passed all kinds of corrosion tests (DIN EN ISO 9227 (incl. adhesion test afterwards), VDA 233-102, etc.) in the automotive industry. Particularly winter salts combined with brake-pad dust create severe problems for a plated surface. ePD™ has “unlimited” corrosion resistance (over 1 000 hours CASS test without damage), if inert metals are used in the PVD-layer. The UV topcoat protects the PVD layer additionally but even with mechanical impacts like stone chipping no corrosion occurs. However, with a highly corrosion-resistant surface, the brightness is lower by about 2 to 4 points.

Chemical resistance:
ePD™ has passed OEM approvals for the automotive sector.

Wear resistance:
The wear resistance has been approved for the automotive interior, exterior and sanitary industry.

Adhesion between coating and substrate:
The adhesion of the UV primer is controlled by the resin technology. A physical/chemical adhesion mechanism assures the bondage, and therefore, unlike traditional plating, no adhesion problems occur especially after temperature cycling.

Sunlight resistance / UV resistance:
The final UV resistance is controlled by the UV topcoat, which is stabilised by a UV-enhanced package. This package prevents the system from long-term degradation or yellowing. The tests are specified on methods required by weathering (Florida, Arizona, and Kalahari exterior test) or accelerated weathering simulations.

Temperature resistance:
ePD™ is highly resistant to temperature changes from -40°C to +80°C. Ultimately, the temperature resistance depends on the type of plastic.

Geometry:
ePD™ can be used for all shapes/geometries. The parts can be very small (i.e. design trims, buttons, etc.) up to large parts (1.5 m) i.e. automotive front grills or bumper trims. Restriction for coatings inside: diameter = depth.

Radar transparency:
The inbound and outbound radar transparency of metallised plastic parts is possible, for example, for safety distance control solutions integrated into the front grills of cars or lane departure warning sensors in the exterior trim.

Contact sensors:
The integration of capacity sensing technologies in metallised plastic components offer attractive design solutions, such as door handles responding to touch or electronic control panels and sliders.

Day/night design:
The integration of capacity sensing technologies in metallised plastic components offer attractive design solutions, such as door handles responding to touch or electronic control panels and sliders.

Transparent or translucent on closed surfaces:
The thin PVD coatings can be made translucent for light sources beneath the coated part. At night and when dark, coated parts – that look metallic during the day – can provide signal lighting or back lighting.

Implementation

Commercially, customers would need to replace their ex-isting chrome plating machines with the new ePD™ technology. The cost of investment for one standard sys-tem INUBIA I with full automation would be slightly high-er to that of investment in chrome plating machines. A single INUBIA I system would suffice to realise the same throughput of parts as a traditional electroplating line. Depending on the geometry or size of the parts, either ePD™ or electroplating is more cost efficient.
The anticipated timeline to install ePD™ is estimated to be 18 months for machine assembling, installation and ramp-up.

Operational expenses

Labour costs:
Work with the INUBIA I system requires two operators for the machine and a certain amount of workers for loading, unloading, inspection and logistics. This is comparable to conventional metal plating technologies hence it is job neutral.

Throughput:
The throughput of parts is 1:1 in comparison to electro-plating. Cycle times of 35 seconds per coating unit (spin-dle) are achieved.

Material costs:
The material costs are the same compared to convention-al metal plating technologies (the very thin PVD-layer is cheaper; the UV lacquer is more expensive).

Energy costs:
Energy consumption is lower than in electroplating.

Case/substitution evaluation

The case study shows a technical alternative to decorative chrome plating of plastics for certain applications. The feasibility and applicability of this alternative technology must be examined on a case-by-case basis.

State of implementation

In use

Enterprise using the alternative

Oerlikon Metaplas GmbH Schmeienstraße 51, 72510 Stetten a.k.M., Germany Tel. +49 7573 9514-0 Fax +49 7573 9514-10 https://www.oerlikon.com/balzers/epd

Availability of Alternative

The ePD™-Technology was developed by Oerlikon Balzers Coating AG and has been in industrial use since 2011 under the brand ePD. Oerlikon offers the custom-ers coating systems (equipment and production concept) for sale; either as a fully automated process for large scale production or as a batch process for small produc-tion runs. Alternatively Oerlikon works as a contract coater.

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