Submission of Information on ALTERNATIVES (NON-CONFIDENTIAL)
Submission of information on
third party submission of information on alternatives for
Applications for Authorisation
non-confidential
Legal name of submitter(s):ESTAL, European association of Surface Treatment on Aluminium
ESTAL is registered with the EU Transparency Register Nr. 480935331-36
On behalf of its member companies, the European association of Surface Treatment on Aluminium (“ESTAL”), an international federation of national associations engaged in the powder coating and anodizing of aluminium, wishes to contribute to the consultation on alternatives opened by ECHA, further to the Application for Authorization of the substance Chromium Trioxide introduced by Lanxess et al.
For reasons explained below, it is not possible for ESTAL to comment on the individual alternatives advanced by Lanxess. Comments apply to the 6 alternatives (relevant for aluminium surface treatment) in general.
About ESTAL and powder coating on aluminium
ESTAL, the European association of Surface Treatment on Aluminium is an international federation of national associations, representing more than 330 companies engaged in surface finishing - anodising and powder coating - of aluminium. Applications are in large part for use in the building, automotive and general engineering sectors.
For powder coating of aluminium, the profiles or sheets, after cleaning and etching, receive a conversion layer which has to assure corrosion protection of the substrate as well as good adhesion of the layer of powder that is applied over the conversion layer. The coating process ends with the curing of the powder layer at temperatures of typically 180 °C.
ESTAL on hexavalent chromium for aluminium powder coating
CrO3 is the substance that has for many years fulfilled the functions of corrosion protection and adhesion in a very robust way. It is important to note that, after the curing of the powder layer, the hexavalent chromium is largely reduced to trivalent chromium.
The member-companies of ESTAL are very well aware of the CMR classification of CrO3. They implement the risk management measures that are necessary, and they comply with european and national workplace regulations. Due to the reduction of Cr6 to Cr3 in the curing process, the risks for consumers and for the environment are of course minimal.
The concern related to the intrinsic properties of Cr6 has, since long, incited ESTAL powder coaters and their chemical suppliers to undertake and promote development of alternative conversion layer pre-treatments. Several different alternative pre-treatment systems have been introduced on the market over the years. Nowadays nearly half of the ESTAL powder coaters use alternatives.
ESTAL’s double-track position on chromiumtrioxide
In 2009 ESTAL adopted a ‘double-track’ position as follows :
“Cr6 has a long track record of extending the life of aluminium in buildings. Until alternative systems demonstrate a comparable track record, we believe its use should continue”
This double-track position has been reconfirmed recently, after comprehensive evaluation and discussion in the national associations of ESTAL, as well as in the executive committee of ESTAL.
In the light of its double-track position, ESTAL supports the application for authorization of CrO3 introduced by Lanxess et al., while insisting on further development of alternative systems.
Comments on alternatives in the AfA of Lanxess et al.
Lanxess et al. introduced their Application for Authorisation of CrO3 for 6 ‘uses’.
Of immediate relevance for ESTAL’s powder coaters of aluminium is use 5 ‘Surface treatment (except ETP) for applications in various industry sectors namely architectural, automotive, metal manufacturing and finishing, and general engineering’. Use 1 ‘formulation of mixtures’ is of direct importance for the suppliers of chemicals to ESTAL member companies. An analysis of alternatives is presented by Lanxess et al. on the level of ‘use 5’, not on the level of the formulation of mixtures.
Within use 5, the architectural applications are most relevant for ESTAL, but our members also carry out powder coating for the different other types of applications in industrial sectors for which Lanxess et al. have applied for authorisation.
In the present comments, the focus is on alternatives for architectural applications.
Of the 10 alternatives indicated in the AfA, the first 6 are mentioned to be applicable for aluminium, the remaining ones are for copper or other metals.
The alternatives according to the Lanxess AfA are :
1 : Acidic surface treatments
2 : Cr3 based surface treatments
3 : Silane/Siloxane and sol-gel coatings
4 : Manganese-based processes
5 : Molybdates and Molybdenum-based processes
6 : Organometallics (Zr- and Ti-based products)
As the AfA correctly mentions, ‘approval’ of pre-treatment systems and coating powders and ‘licencing’ of applicators by quality label organisations Qualicoat or GSB are widely accepted procedures for evaluating and assuring the quality of powder coated aluminium for architectural applications.
At the start of the powder coating technology some thirty years ago, and for a long time since, the use of a conversion layer of CrO3 has been the preferred pre-treatment method. The CrO3 conversion layer has proved to be a very robust technology, a very tolerant system.
As alternative pre-treatment formulations were developed in order to replace the CMR CrO3 - which ESTAL firmly supports - , Qualicoat and GSB have granted ‘approvals’ to several of the above mentioned alternative ‘pre-treatment system’ formulations. The exact composition of suppliers’ formulations is proprietary, not known to the downstream users unfortunately. Sometimes such proprietary formulations might be a combination of two of the above alternatives. It is therefore not possible for ESTAL to comment on the individual alternatives advanced by Lanxess. Comments apply to the 6 alternatives (relevant for aluminium surface treatment) in general.
The quality label ‘approvals’ of alternative systems are largely based on laboratory results. The scaling up of successfully tested chemicals from the laboratory to practical application is not a straightforward exercice. For instance, in seaside or industrial environments, difficulties arise which are not yet fully understood.
All of the approved alternative systems have important limitations :
- To begin with, practical experience shows that alternative systems are much more sensitive than CrO3-layers (operational parameters are in narrow margins)
- None of the alternative systems has the ‘self-healing’ property that Cr6 has (R&D is ongoing, but short-term industrial application is very unlikely)
- No single alternative has a multi-metal applicability (e.g. zinc-coated steel and aluminium)
Nowadays, nearly half of the ESTAL powder coaters are using or have been using alternative pre-treatment systems. No alternative however has been applied more than others, and no alternative stands out as a clear best technique. Some coaters, after having used alternatives for some time, have returned to Cr6, because of operational complications and quality problems.
With the alternative systems, increases have been observed in the number of failures to meet the quality requirements of the quality label organisations. Most failures appear to be related to poor corrosion protection, or to adhesion problems of the powder coating resulting in negative mechanical tests.
In view of the more frequent occurrence of failures, ESTAL has insisted that Qualicoat and GSB set up comprehensive evaluation programmes of the different possible alternatives including chromium trioxide. Indeed, the label organisations have access to detailed information about the negative test results that are seen in the frequent, unannounced inspections of processes and products that they impose in their specifications. Such evaluation programmes are ongoing, but because of the multivariate parameters that may give an indication of the reasons for the failures, the programmes are complex and need much more time. Clear conclusions can not yet be drawn.
ESTAL and its national associations strongly support Qualicoat and GSB in their continuing evaluation research.
What has already come out of the evaluations, is that all links of the quality chain are of importance : the aluminium alloy that has to be coated, the pre-treatment system that is used, the powder that is applied, and of course the way the powder coater is conducting all steps of the process.
Job coaters have to treat the different aluminium substrates that are brought in by their customers. Alloy elements and even small amounts of impurities and the way they appear (e.g. Cu or Fe, Mg and Si as stand-alone elements or as compounds) have an influence on the corrosion protection provided, and more particularly as a function of the pre-treatment used. In that respect, alternative, chromefree pre-treatments are much more sensitive to alloy composition than is the case with chromiumtrioxide. Job coaters can not effectively control the substrates that are brought in by their customers, and therefore they need pre-treatments that allow wider operational margins.
Also, it has more recently become clear that the combination of (alternative) pre-treatment and powders has an effect on the adhesion of the final coat. In some cases a Qualicoat approved powder applied on a Qualicoat approved (alternative) pre-treatment leads to unacceptable product quality. It appears that powders have in the past been optimized for application on Cr6 pre-treatment. Therefore powder manufacturers have to be convinced of the need to cooperate closely with chemicals suppliers in order to optimize powders for each specific alternative pre-treatment.
To sum up, a closer cooperation between the suppliers of the aluminium substrate, the chemical pre-treatment suppliers and the powder manufacturers is clearly necessary. ESTAL continues to facilitate information exchange and cooperation between interested parties, also on the level of industry associations.
A further alternative - REACH leakage
Another realistic alternative from the point of view of the downstream user consists in carrying out the powder coating - using Cr6 as conversion layer - in countries outside the EU. This alternative is technically feasible and economically very attractive. The economic attractiveness is further increased when also the uncoated aluminium profiles and sheets are procured from sources near the finisher i.e. also from outside the EU.
Socio-economic considerations of alternative pre-treatments
For the granting of an authorization, when assessing whether suitable alternative substances or technologies are available, the Commission has to take into account the technical and economic feasibility of alternatives for the applicant (art 60.5).
The Socio-Economic Analysis included in the AfA of Lanxess et al. goes a long way in presenting socio-economic considerations. Nevertheless, when viewed from the standpoint of ‘very far’ downstream users such as powder coaters, certain important elements are missing.
For the sector represented by ESTAL powder coaters, some of the socio-economic considerations are related to the extra-investments at the level of these DU’s.
It is clear for instance, that much more narrow operational tolerances have to be respected when working with alternative, chromefree pre-treatments. This implies investments in control systems, and in additional follow-up testing. Generally speaking, much more intense rinsing has to be applied at various process stages, leading to additional investment in demineralized water production (resulting in release of extra pollutants emissions into the environment). Most important of all is the fact that the lay-out of the coating lines may need extensive modifications or extensions.
For alternative 1 ‘acidic surface treatment‘, such treatment before applying the powder layer is only available to a very limited number of coaters. Indeed, pre-anodising has to be performed in a completely separate plant, but situated on the same location as the powder coating line, because the anodic layer, for good adhesion of the subsequent powder coat, should not be sealed. Only few plants have combined anodising and coating capability. Besides, both treatments needs a different jigging of the components to be treated : the extra manpower and manipulation needed leads to a quasi doubling of the cost of the process.
For the Cr3 alternative, one should not forget that the production of Cr3 compounds commonly starts from Cr6 compounds that are reduced to Cr3. Therefore, the authorisation question is shifted to the manufacturing of the Cr3.
Also there are no alternatives at all, that can treat multi-metal applications (e.g. zinc-coated steel and aluminium). This means that, if a coater can no longer use Cr6, he either has to dedouble (part of) his coating line, or to stop treating one of the metals.
A further socio-economic consideration has to do with the attitiude and perception of customers, architects and prescribers. Joinery companies ask for very long guarantees, up to 30 years and longer. As long as customers doubt whether such long lifetimes can be guaranteed with alternative pre-treatment systems, they may prefer to order powder coating with CrO3 conversion layers performed outside the European Union. Because of the reduction of Cr6 to Cr3 during the curing of the powder coat, aluminium profiles and sheets powder coated on a Cr6 base, can be imported into the EU without any REACH obligations.
ESTAL asks that such socio-economic considerations from the point of view of specific ‘very far’ downstream users should be taken into account by the ECHA SEAC when defining its ‘opinion’, and by the Commission when deciding on the Application for Authorisation.
A Review Period of 12 years is proposed
Lanxess et al. propose a review period of 7 years for ‘use 5’.
ESTAL is of the opinion that more time is needed to evaluate the long-term performance of powder coatings on aluminium based on chromefree pre-treatments. The quality label organisations Qualicoat and GSB should be given enough time for their evaluation programmes, which include longer term exposure of coated samples in harsh environments, in particular in Florida.
Another issue is the discrepancy with the 12 year review period asked for ‘use 1’ formulation of mixtures. All Cr6-containing formulations for the conversion layer for aluminium before powder coating are supplied by ‘formulators’. There are no powder coaters that formulate their own mixtures. Formulators in the scope of ‘use 1’ are themselves already downstream users of the applicants (Lanxess et al.). For legal certainty, it is important for the formulators that their downstream users, the powder coaters, should be allowed the same review period of 12 years.
Conclusion
In conclusion, ESTAL fully supports the Application for Authorisation introduced by Lanxess et al.
Current experience shows that closer cooperation between aluminium suppliers, suppliers of alternative pre-treatment, and manufacturers of powders is needed to optimize all links of the quality chain. ESTAL strongly promotes such cooperation.
Because of the required long term quality for architectural applications, ESTAL suggests a review period for ‘use 5’ that is consistent with the 12 year review period that is asked by Lanxess et al. for ‘use 1’ ‘formulation of mixtures’.
Contact for further information : Simon Meirsschaut, ESTAL Technical Coordinator
0032-05 / Chromium trioxide / 215-607-8 / 1333-82-0 ESTAL Comments 7 october 20151