Press Release No 7 – January 2009: International Bitumen Emulsion Federation Position paper – Obligations of producers and appliers of bituminous emulsions with regard to REACH Manufacturing and use of bituminous emulsions
Bituminous road emulsions are manufactured in dedicated production plants which sell the product to its final user which applies the emulsion, either by spraying (emulsions used for surface dressings or tack coats) or by the in place manufacturing and applying of slurry-seals or micro-surfacing or by applying cold mixes (grave-emulsion or dense cold mixes of emulsion and aggregate) previously mixed in ad-hoc mixing plants.
Emulsion production plants do thus indeed place new products (the emulsions) on the market but, as it will be demonstrated further down, those products are by no means new substances to be registered within REACH.
As a matter of fact, the manufacturing of an emulsion proceeds according to the following successive steps (we consider hereafter the case of cationic emulsions but a similar reasoning applies to anionic emulsions).
Making of an aqueous phase
Solution in water of:
– a surfactant (amine) which acts as a base
– an acid (usually HCl, sometimes H3PO4)
This solution (called the aqueous phase of the emulsion) is indeed the solute form of a salt but it has by no means as a final objective the isolation and the production (by dehydration or precipitation) of a salt to be placed on the market. The aqueous phase only constitutes an intermediary manufacturing step and is not place on the market as such.
In some cases, which become more and more frequent in fully automated plants, this intermediate step is abandoned and the components of the aqueous phase are introduced separately, at an appropriate timing, when manufacturing the final preparation, i.e. the emulsion, in a single step process.
Manufacturing of the emulsion as such
Consists in dispersing, in the form of fine droplets and by the means of intense mechanical shear, a bituminous binder into the previously manufactured aqueous phase (let us remind that in some industrial processes all the previously described steps may be done in-line). When manufacturing the emulsion, the majority of the cationic ions obtained from the original amine get adsorbed at the surface of the bitumen droplets, thus ensuring the stability of the emulsion (the very purpose of the surfactant). The remaining residual cationic ions stay in the aqueous phase, assembling themselves into micelles or staying free.
A bituminous emulsion may thus be considered as being an aqueous ionic mixture. The manufacturing of an emulsion, even if it goes through an intermediate phase in which one neutralizes a base with an acid, can be no means be assimilated to the production of a new chemical substance such as an ammonium salt. The purpose of the cationic ions is to stabilize the bitumen droplets, not to associate with the anionic ions so as to precipitate in the form of a salt.
Moreover, all the precursors of the mixture (bitumen, acid, and amine) will be registered up the supply chain by their suppliers and the corresponding chemical safety assessments will take into account
their use within the particular ionic mixture formed by the bituminous emulsion (it is reminded that the very purpose of the supplied amine is indeed to be used as an emulsifier!).
These considerations allow us to conclude without any ambiguity that the manufacturing and placing on the market of bituminous emulsions perfectly satisfies the conditions for exemption as clarified for entry 3 of Annex V of the REACH regulation by the « Draft Guidance for Annex V » in the version published 2008-11-07 on the ECHA (European Chemicals Agency) website http://echa.europa.eu/
“This entry also covers substances present as ionic mixtures in water-based solutions as a result of mixing salts, acids and bases without creating new covalent bonds. Registration would be inappropriate for these substances as the resulting ion pairs are not manufactured substances as such and isolated from the solution, but formed as part of the chemical equilibrium in the solution only. This applies if all acids, bases and salts mixed (i.e. introduced into the solution) have already been registered by an actor up the supply chain (or are exempted from registration) and the chemical safety assessment covers the use of a certain acid, base or salt in the relevant ionic mixture so as to identify a potential change of the hazardous properties of the mixture compared to its constituents, due to the presence of the salts formed in solution……
It must be emphasised that deliberate neutralisation of acids or bases to form the corresponding salts, including neutralisation during formulation, is usually a manufacturing process and is not covered by this entry”.
Moreover, possible chemical reactions between the cationic ions and the bitumen droplets (which most likely are only Van der Walls or hydrogen bonds) fall under the exemption cases foreseen under entry 4 of Annex V. As a matter of fact, the amended version published in the OJEU, Official Journal of the European Union, on October 9th, 2008, does not change versus the initial version. It clearly states:
« Substances which are not themselves manufactured, imported or placed on the market and which result from a chemical reaction that occurs when:
(a) a stabiliser, colorant, flavouring agent, antioxidant, filler, solvent, carrier, surfactant, plasticizer, corrosion inhibitor, antifoamer or defoamer, dispersant, precipitation inhibitor, desiccant, binder, emulsifier, de-emulsifier, dewatering agent, agglomerating agent, adhesion promoter, flow modifier, PH neutraliser, sequesterant, coagulant, flocculant, fire retardant, lubricant, chelating agent, or quality control reagent functions as intended; or
(b) a substance solely intended to provide a specific physicochemical characteristic functions as intended.”
In that respect, the “Draft Guidance for Annex V” explains:
“In some cases the mode of action of a substance performing a specific function involves a chemical reaction. Provided that this reaction does not take place during a deliberate manufacturing process, the substances resulting from this chemical reaction do not need to be registered as the risks of the substances produced will be assessed through the assessment of the precursors of the reaction”.
Emulsifiers are quoted as an example (§ 4.-vi in Draft Guidance for Annex V):
“One example of a surfactant is an emulsifier, i.e. a substance that lowers the interfacial tension between immiscible liquids (e.g. oil and water) thereby allowing them to mix.
Whenever a chemical reaction takes place with a substance in the context of its use as surfactant, the substances thus formed do not have to be registered”.
Application of bituminous emulsions
The entity which applies the bituminous emulsion, whether directly (spraying applications) or via a preliminary mixing with aggregates, acts as an end user of the product. In all these applications, the emulsion is induced to break when brought into contact with a mineral surface (aggregates) and the chemical reactions likely to happen (and which are sought for) are the adsorption of the bitumen droplets onto the mineral surface via the cationic ions. The same happens to the “free” cationic and anionic ions which are still in the aqueous phase. Also here, all the reactions likely to happen when applying bituminous emulsions will be dealt with when making the risk assessment of the “precursor” substances, i.e. the acids, amines and the bitumen.
We are again perfectly in line with the “Draft Guidance for Annex V” when it says, concerning entry 3 of Annex V:
“The end use of a substance on its own, in a preparation or in articles can result in an intended chemical reaction, such as during the use of an adhesive. However, provided that the reaction products obtained cannot be regarded as having been isolated from a manufacturing process or having been placed on the market, these reaction products are exempted from the registration provisions. Note, however, that the potential risks associated with the substances produced must be taken into account in the assessment of the precursors/reactants of the reaction. Please note that the term “end use” is not limited to the use of a substance by professional or private consumers but includes any intended downstream use of a substance in the supply chain, provided it is not part of a manufacturing process of a substance.”
From the above made analysis, IBEF considers that at whatever stage of the manufacturing and application of bituminous emulsions, there is neither creation nor placement onto the market of a new chemical substance due for registration under REACH. Bituminous emulsions fully comply with the different cases of exemption foreseen by the latest amended version of Annex V of the REACH regulation (published in the OJEU of 2008-11-09) and as explained in the “Draft Guidance for Annex V” posted on the ECHA website (http://echa.europa.eu) on 2008-11-07.
IBEF would also like to emphasize that the registration of all the substances used for the manufacturing of bituminous emulsions is deemed to take into account comprehensive exposure scenarios, from the manufacturing down to the application and breaking of the emulsion, with a risk assessment at every step. The primary objectives of REACH registration will thus be perfectly and entirely met.
Bituminous emulsions are not be registered under REACH
IBEF’s position is to act as responsible downstream users and to thoroughly check that our suppliers fulfil their registration duties under REACH while taking into account all the various emulsion application scenarios.