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06 Sep 2006  -  Germany

Star quality for flatscreen TVs

On July 9, the World Cup will be over but the German Electrical and Electronic Equipment Act remains in force. Since March 24, it has no longer been permissible to dispose of televisions as household or bulky waste. They must be taken to special recycling centers, where they are collected in dedicated containers. TV manufacturers are now responsible for environment-friendly recovery of this equipment.

To relieve the future burden on the environment, TV manufacturers have generally been ahead of the game in material selection for new televisions, for example by dispensing with heavy metals or using plastics that contain halogen-free flame retardants. This is also a requirement of the Electrical and Electronic Equipment Act that will apply from July 2006.

To provide a sharp, high-contrast picture, the TV screens are backlit by neon tubes. The holders for these tubes are produced from Celanex XFR. Ticona’s PBT grade reinforced with ten percent glass fibres offers good toughness and excellent rigidity. This facilitates assembly and ensures that the tubes – and therefore also the contacts – are held in a firm grip. Another key selection criterion is compliance with the highly demanding requirements of the US Underwriters Laboratories (UL) flame classification UL94 V-0 at 0.8 mm thickness.

UL94 is a benchmark for the flame retardancy of plastics. In this vertical flame test, a Bunsen burner simulates the outbreak of fire. The burn time after flame removal and whether or not the test specimen drips flaming particles are key classification criteria. With a burn time of less than ten seconds and no flaming particles, plastics with the V-0 flame classification meet the highest requirements.

New phosphorus-containing flame retardants have made it possible to dispense with heavy metals, while at the same time achieving the highest UL flame classification. They consist of salt-like, heat-stable, halogen-free compounds. They prevent the outbreak of fire or delay it as long as possible. In the gas phase, the flame retardants remove high-energy, flame-propagating radicals by chemical reaction. On the surface they form a carbon-like layer as a result of decomposition and crosslinking. This protects the material underneath from heat and flame attack. At the same time, there is physical intervention in the combustion process through dilution with the non-flammable gases and water vapor that are formed.

Four halogen- and antimony-free, flame-retardant Celanex grades are now available for special electrical and electronic applications. Their patented flame retardant system is based on an organic phosphorus compound. Even components with wall thicknesses from 0.8 mm have very good flame retardancy. This is also confirmed by UL94 V-0. Other advantages: components made from Celanex are easy to produce and colour.

Source : Ticona