JEC COMPOSITES MAGAZINE - Issue #73 - June 2012 - 69

Fig. 1: Bioaccessibility of ECOS ND15 and cobalt sulphate

Fig. 2: Comparison of ECOS ND15 with standard cobalt octoate

*AAF: Artificial Alveolar Fluid Comparable results obtained in Gambles solution (interstitial lung fluid)

ECOS ND15 consists of a high-molecular-weight matrix in which cobalt is incorporated. Its reduced solubility in aqueous media will also limit its bioaccessibility. Figure 1 shows that its bioaccessibility in body fluids (lung fluid and intracellular fluid) was assessed to be more than 100 times lower than that of cobalt sulphate. Its solubility in distilled water (lower than 10 mg Co/l) proves to be more than 10,000 times lower than that of cobalt sulphate (140,000 mg Co/l). Bioaccessibility results ROS (reactive oxygen species) formation was studied because of the potential of cobalt ions to generate ROS and the potential of ROS to cause genotoxicity. It was demonstrated that ECOS ND15 does not induce any ROS formation at biologically relevant concentration levels. In a subsequent part, the modified Comet Assay was performed. In addition to detection of DNA cleavage events (DNA damage), this technique allows monitoring of ROS-driven DNA modifications. The presence of genotoxicity/mutagenicity is considered a required precedent of primary carcinogenicity. ECOS ND15 did not demonstrate any DNA damage (DNA strand breaks or oxidative modifications) at biologically significant concentration levels. In the regulatory toxicology part, the requirements for polymers were followed as specified in Annex VII of the Dangerous Substances Directive (67/548/

EC). Although polymers are exempted from REACH registration, these requirements basically correspond to Annexes VII and VIII of the REACH regulation (EC/1907/2006). A basic dataset including the acute toxicity studies was developed, showing that ECOS ND15 is non-hazardous, showing a correlation between reduced bioavailability and low toxicity. Further tests are being carried out to complete the data package, the results of which are communicated via the Safety Data Sheet. The hazard assessment demonstrates that embedding cobalt in a polymer structure results in a product with reduced aqueous solubility, reduced bioaccessibility and consequently a reduced toxicological profile.

Application results in polyester and vinylester resins
ECOS ND15 is an ideal drop-in replacement for existing cobalt compounds. It has proven to be an effective catalyst for the drying of inks and coatings and the acceleration of UPR and gelcoats. One example is given in Figure 2, where the gel time is plotted as a function of the amount of accelerator used in a standard medium-reactive orthophthalic polyester resin for vacuum infusion. Generally, non-cobalt metal complexes do not follow the same behaviour as cobalt octoate, thus the formulation has to be significantly modified to obtain the same gel time and peak exotherm. In contrast, ECOS ND15 showed close to a 1:1 replacement for the whole range of typical UPR cobalt concentrations.

More information ...
Umicore: Umicore’s Cobalt & Specialty Materials (CSM) business unit has been a global leader in the refining, transformation and marketing of cobalt specialties since 1912. Currently, CSM markets a unique and complete portfolio of cobalt chemicals and can rely on a fully integrated supply and transformation chain for cobalt. Since 1980, CSM has completed its portfolio with nickel chemicals and since 2007, with a broad range of metal carboxylates for various catalytic applications. Today, CSM has production plants and sales offices for its cobalt and other specialty materials on all continents. Reichhold: Founded in 1927, Reichhold is one of the world’s largest producers of unsaturated polyester resins and has manufacturing operations and R&D centres all around the world. Reichhold is committed to the long-term sustainable competitiveness of composite materials by proactive participation in the European Cefic UPR Sector Group and by developing and offering environmentfriendly products based on renewable, recyclable, monomer-free and low-VOC systems under the ENVIROLITE® brand. Testing and approving sustainable cobalt solutions for effective UPR curing are part of Reichhold’s responsible and proactive support of the composite industry.

No73 June 2012

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JEC COMPOSITES MAGAZINE - Issue #73 - June 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #73 - June 2012