wax models increase of the strength in wax models and the required flowabili- ty to the wax and has no real substitutes. In investment casting applications it is exclusively used encapsulated or em- bedded in wax matrices (consisting of paraffins, resins, polymer bases, hard waxes etc.) with no possibility of free flowing. Following some features of XLPS


are provided: i. Chemical name: Cross linked


PolyStyrene (XLPS); Polymer Struc- ture: Styrene/Divinylbenzene; Phys- ical Form: Transparent beads.0-400 microns; Odor: No odor; Reactivity: Chemically inert; Moisture Content: 1% max.; Specific Gravity: 1.02 to 1.05 gr/cm3;


Bulk Density: 0.63 to 0.7 gm/ml


Thermal Stability: 200º C (392º F); Maximum Ash Content: 0.05% max. ii. XLPS is used between 5 to 40% as filler material in an Investment Cast- ing wax formulation in combination with resins, waxes and additives. iii. XLPS is used as particles of 0


to 400 micron in the casting wax for- mulation. The particle shape can be spherical (beads) or irregular (ground material). iv. XLPS has no solubility in water


and decomposes above 200ºC. XLPS is chemically inert as is the function of a filler in the application. v. XLPS has no or very slow biotic


degradability. vi. XLPS is used around 2000 MTA


as filler in investment casting wax in the EU. vii. Investment casting waxes with


incorporated XLPS filler are after usage either recycled or disposed of accord- ing to regulations at the end of the life cycle. As the XLPS particles are encap- sulated with wax and resin there is no contact with water or flushing out into the drainage system. XLPS is an ideal filler for Investment


Casting waxes as it reduces cavitation in the wax pattern, increases the setting and the window of operation. XLPS is chosen based on: • Low thermal conductivity • Ideal density, close to wax/ resin mixture which prevents settling • High thermal stability (>200º C) • Low thermal expansion


®


• Low in inorganic components There is not really any suitable al-


ternative. XLPS is nearly unique. 95% of waxes use XLPS due to its outstand- ing properties. Any restriction on the use of XLPS material in investment casting wax compounds would have a dramatic effect on the production and quality of the finished castings manu- factured within the industry. There are currently no equivalent filler materials that can be used. The other options are also microplastics that are essential to control thixotropy of the wax (com- plexity of components). The technical advantages of XLPS based products cre- ate a competitive advantage and gain market share compared to previous known fillers as Terephthalic acid (PTA) and water. The use of other known al- ternatives would jeopardize the Euro- pean investment casting industry and associated sectors due to the economic impact of the new validation and cer- tification processes that aeronautical components have to comply with and the investments required to produce new wax injection moulds and adapt the production to the features of any currently available alternative. If candidates are identified in the


future the dimensional aspects provid- ed by the wax would probably change and this would entail the need of huge resources in terms of time and invest- ments to adapt the moulds to the new materials in terms of certification and validation of aeronautical components (the main market of IC in Europe). The risk of outsourcing the


production to countries were the directive would not apply is real for some non-critical components even though this outsourcing is not possible in many other cases due to the risk of disrupting the supply of critical strategic Defence and aeronautical components due to confidentiality issues and defence strategy. It should be noted that XLPS is


widely used in water softening treat- ment, paint manufacture, tyre man- ufacture, oil drilling lubricants and numerous other applications. It is true that other alternatives may exist for these other applications but this is not


the case for the application of XLPS as a filler for the wax in the investment casting sector. Investment casting industry is a


strategic industrial sector for Europe. Also called precision casting it provides components that cannot be produced by any other casting processes due to the nature of the expendable moulds. The impact of a restriction in the


use will affect over 95% of pattern wax supplied to the Precision Invest- ment Casting Industry. The PIC indus- try supplies XLPS containing material to critical industries including aero- space, energy generation and medical prosthesis. These industries rely on XLPS filled wax product to create their products for the final customer. These processes are fixed processes with no changes to raw material allowed by the suppliers. A change to the restriction on microplastic use within this industry could have a knock-on effect to supply of finished goods if a restriction was applied. The restriction would lead to loss of employment and of strategical sectors and clients. The total market of IC is 14000


million of dollars and Europe has an important share of around 25% of it, i.e. around 3100 million and 95% of the components produced in Europe are made with waxes containing XLPS. Conventional methods used in the


characterization of polymers can be used to identify microplastics. The high % of microplastics within


the wax and its size allow its identifi- cation through infrared spectroscopy, Differential Scanning Calorimetry ana- lytical processes where the peak cor- responding to Polystyrene should be clearly and quickly identified.


Conclusion At the end of April 2018, EICF has contributed to the call for comments and evidence launched by the ECHA by filling the questionnaire prepared by the latter. The EICF´s contribution has been submitted online. The main conclusion of the information provided by EICF is that EICF requests not to include XLPS in the list of microplastics to be restricted for its use in the investment casting sector.


November 2018 ❘ 9


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