Plastics cadmium pigments

It is announced in this short article that the European Commission has voted for no further restrictions on the marketing and utilisation of cadmium pigments to colour plastics, thereby halting the trend of recent years in reducing the number of applications in which these pigments are permitted. Brief details are provided. EUROPEAN COMMISSION... 

Journal of Coatings Technology 71, No.896, Sept. 1999, p.14 EUROPEAN COMMISSION FOREGOES ADDITIONAL RESTRICTIONS ON CADMIUM PIGMENTS USED IN PLASTICS... 

An EC study has found that cadmium pigments present no significant threat to human health or the environment, says the International Cadmium Association. In view of the positive life cycle assessment, EC Member States voted earlier this year that there should be no further restrictions on the marketing and use of cadmium pigments in plastics. INTERNATIONAL CADMIUM ASSOCIATION... 

Because of their brilliant pure red and yellow shades cadmium pigments, e.g. Cl Pigment Red 108, CdS-xCdSe, have found widespread use in the coloration of plastics, but toxicological problems have led to restrictions on their use and to the introduction of safer replacement products. 

Cadmium pigments are mainly used to color plastics. They have brilliant, pure shades (yellow, orange, red, and bordeaux), good hiding power, and moderate tinting strength. 

A very useful feature of plastics colored with cadmium pigments is the dimensional stability of injection-molded parts with a large surface area. The combination of these properties is not matched by any other class of colorant. 

Regulations Affecting Foods. The cadmium pigments fulfill the legal requirements of the EC countries for colorants used in plastics which come in contact with food. 

The output of cadmium pigments in the industrialized countries in 1995 was approximately 3000 t, of which approx. 2000 t were produced in Europe and 500 t in the United States. Consumption is distributed approximately as follows plastics 90%, ceramics 8% and others 2%. 

Limitations of Use. In 1981 Sweden prohibited the use of cadmium pigments (with some exceptions) for ecological reasons. In 1987 Switzerland prohibited the use of cadmium pigments in plastics. Exceptions are possible if valid reasons can be given. 

In 1991 the EU passed a directive to prohibit the use of cadmium pigments as colorants for certain plastics that can easily be colored with other pigments [3.122]. A transition period was granted for further series of plastics, these must not be colored with cadmium pigments since 01.01.96. The maximum cadmium content in plastics is limited to 0.01 %, because in this range only technical caused impurities are possible and a technical convenient coloring is not practicable. 

In the Thermofuel process, carbon and coke deposits formed during the pyrolysis are continuously scraped from the pyrolysis chamber walls and reduced to a free-flowing black powder. Inorganic additives such as cadmium pigments from the plastics also end up in the char stream. The carbon matrix has a metal fixing effect and binds up the metal ions so that no leaching occurs after disposal. 

Cepria and coworkers used the voltammetry of immobilized microparticles to detect and quantify the cadmium pigments (e.g., cadmium sulfide and cadmium sulfoselenide) used in artists paints, as well as in glasses, plastics, ceramics, and enamels [141]. For this, a simple, fast and reliable technique was developed that proved to be especially applicable for valuable art objects, as it was minimally invasive and required only nanogram quantities of material (see also Section 6.4.1). For quantification purposes, an abrasive stripping scan was used from + 0.3 V to —1.0 V, following a 10 s pre-treatment step at —1.5 V. The Cd oxidation peak was evaluated with respect to an internal AgCl calibration standard. 

Rade D and Dornemann A (1981) Migration studies on Cadmium Pigments in Plastics. In Cadmium 81 Edited Proceedings, Third International Cadmium Conference, Miami, USA, 3 -5 February 1981.Cadmium Association/Cad-mium Council/ILZRO, London, UK. 

Chek-Mate. [Ferro] Cadmium pigments for plastic. 

Cadmium ranks close to lead and mercury as a metal of current toxicological concern. Cadmium is used in electroplating and galvanization, and in plastics, paint pigments (cadmium yellow), and nickel-cadmium batteries. Because <5% of the metal is recycled, environmental pollution is an important consideration. Coal and other fossil fuels contain cadmium, and their combustion releases the element into the environment. Extraction and processing of zinc and lead also lead to environmental contamination with cadmium. Workers in smelters and other metal-processing plants may be exposed to high concentrations of cadmium in the air however, for most of the population, food is the major source of cadmium. 

EC member states have voted that there should be no further restriction on the marketing and use of cadmium pigments for plastics. The International Cadmium Association (ICA) believes that this should now be safeguarded for the next three years, when a more far-reaching report on cadmium and cadmium oxide is expected. A Directive (91/338/EEC) was adopted by the EC to harmonize restrictions on the use of cadmium-based pigments that had been introduced by different countries. It does not ban the use of these materials but limits their use. For example, cadmium-based pigments may not be used in plastics materials where there are other satisfactory substitutes. Polypropylene and polystyrene are specifically listed as polymers where non-cadmium pigments must be used where possible. Other polymers where there is a restriction include thermoplastic polyesters, poly(methyl methacrylate), cross-linked polyethylene and melamine, urea, and polyester resins. 

Coloured papers are especially complex in their retention chemistry. They need also to be of certain levels of opacity, so they include titanium dioxide as well. The colour formulations in modem decorative laminates tend now to be very complex. Historically one of the main sources of coloured pigmentation was from materials derived from heavy metals such as lead, cadmium and chromium. However, more environmentally acceptable alternatives were sought in the 1980s, and all the major decorative laminate paper producers are following the lead taken by a British papermaker, who had completely replaced these pigments with organic alternatives by about 1985. (See the entries on Dyes for the mass coloration of plastics, and Pigments for plastics, for further information on related issues.)... 

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