JEC COMPOSITES MAGAZINE - Issue #73 - June 2012 - 68

upr

A sustainable cobalt solution for the UPR industry
Reichhold and Umicore jointly introduce an innovative and sustainable cobalt solution for curing unsaturated polyester resins (UPR). Umicore’s ECOS ND15 offers a breakthrough in terms of hazardous properties. This cobalt alternative has been widely tested in Reichhold’s UPR product range, giving excellent application results and proven to be a 1:1 replacement of standard cobalt octoate.

per Anker hASSel, technology mAnAger, reichholD Wouter ghyoot, ApplicAtion mAnAger cAtAlyStS AnD rApS umicore

urrent cobalt-based products that are frequently used as driers in inks and coatings or as accelerators for the curing of unsaturated polyester resins (UPR) and gelcoats are increasingly under pressure due to the uncertainty about their future hazard classification. This is due to the fact that some inorganic cobalt salts such as cobalt sulphate are classified as lung carcinogen category 1B, reproductive toxicant category 1B and mutagenic category 2 under the EU Regulation on classification, labelling, and packaging (CLP). The key question is whether the same hazard classification will be attributed to the cobalt carboxylates used as driers and accelerators. Hazard classifications must be based on sound scientific data. The implementation of REACH means that more hazard data are becoming available than ever before, including data on cobalt carboxylates such as cobalt bis (2-ethylhexanoate), also known as cobalt octoate. The conclusions from these studies result in hazard classifications, which are communicated with the Safety Data

Sheet, and in warning symbols on the product label. Eventually, they may trigger specific legislation imposing restrictions on the use of such compounds. As an example, for cobalt compounds that are classified as lung carcinogens category 1B, the concentration of cobalt that should not be exceeded in mixtures may become as low as 0.01% cobalt (expressed as cobalt metal content). It is clear that this would jeopardize the use of cobalt carboxylates in inks, coatings and UPR, since the active cobalt concentration required is normally higher than 0.01%. Umicore developed an innovative cobalt-based accelerator named Umicore® ECOS ND15, which is a less hazardous alternative to traditional cobalt carboxylates. In ECOS ND15, the cobalt is embedded in a polymer structure. Besides its excellent application results, this newly developed cobalt compound also offers a breakthrough in terms of hazardous characteristics. Although polymers are exempted from REACH registration, a hazard characterization has been performed to advise users in a correct way, based on sound scientific data.

Hazard assessment
The study of ECOS ND15’s hazard characteristics can be divided in two parts, the first one being a mechanistic study of toxicology and the second one looking into the regulatory toxicology requirements. The bioavailable cobalt ion (Co2+) is considered as the toxic entity in cobalt compounds which is responsible for the observed hazards such as lung carcinogenicity. The catalytic activity (due to the formation of oxygen radicals) was found to play an important role in the mode of action of cobalt toxicity. The attack of DNA by these radicals leading to genotoxicity has been identified as the most critical event preceding carcinogenesis. Taking into account both the bioavailability and catalytic activity, the investigation of the mechanistic toxicology of ECOS ND15 was built on a tiered approach, including the assessment of water solubility, bioaccessibility, ROS (reactive oxygen species) formation potential and DNA damage (Comet assay). All mechanistic toxicology assessments were performed in collaboration with the Fraunhofer Institute for Experimental Medicine (Fraunhofer ITEM, Hannover, Germany).

68 jec composites magazine / No73 June 2012

JEC COMPOSITES MAGAZINE - Issue #73 - June 2012

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