PCB-free silicone compounds 

Gummiwerk KRAIBURG offers peroxide and addition cross-linked compound alternatives holding chlorine-free cross-linking systems for pressure less cross-linking, and which therefore do not form any PCBs.

Gummiwerk KRAIBURG offers chlorine-free silicone compounds, which do not release any polychlorinated biphenyl (PCB) during pressure less vulcanization. Thanks to the use of an alternative cross-linking method, the fission products of these compounds do not hold any PCB. 

 
Peroxide and addition cross-linked compound alternatives  

The manufacture of extrusion articles with pressure less vulcanization (hot air, salt bath) of silicone rubber using the common peroxide DCLBP, Di(2,4-dichlorobenzoyl) peroxide, results in the release of polychlorinated biphenyl (PCB), which is harmful to both the environment and people’s health. 

Gummiwerk KRAIBURG offers peroxide and addition cross-linked compound alternatives holding chlorine-free cross-linking systems for pressure less cross-linking, and which therefore do not form any PCBs. While these compounds do vulcanize slower, this is far from being a decisive factor in high-temperature vulcanization (200 °C or higher) in a hot-air tunnel. The time differences can be reduced so much by raising the temperature that the dwell times in the vulcanization tunnel are hardly that much longer in practice. The odor created during the processing of the peroxidic ally cross-linked DCLBP alternative can be eliminated using an extraction system integrated into the process.  

 

High level of mechanical quality of the addition cross-linked silicone compounds

The addition cross-linked alternative compounds also feature a higher level of mechanical quality than those cross-linked with peroxide. For instance, the elongation at break, e.g. of a standard compound 70 ShA, increases significantly, from 370% to 600%. Similarly, the tear strength increases from 25 N/mm to 42 N/mm according to ASTM D624B. This makes it possible to produce cables and hoses with even better tear resistance and extensibility. In addition, the better compression set of these compounds (24 hours at 175 °C from 33% to 10%) also makes increased pressure stresses possible.  

 

Stricter monitoring and switching to alternative solutions  

Polychlorinated biphenyls accumulate in fatty tissue and damage the nerve and immune systems. In some cases, these substances also lead to cancer and malformations and deformities in unborn children. Quite recently, several manufacturers in the German state of North Rhine-Westphalia were forced to restrict their production activities after dangerous concentrations of PCB were detected in the areas around these facilities. This prompted the state government to impose stricter monitoring on companies processing silicone and encourage manufacturers to switch to alternative solutions. The state of North Rhine-Westphalia has given a recommendation in this matter to Germany’s federal states’ parliament, the Bundesrat. The amendment of the ordinance on industrial plants requiring special approval (the fourth BImSchV [Ordinance on the Implementation of the Federal Immission Protection Act]) is intended, considering the PCB emissions produced by plants processing silicone, to prove a uniform approach to be applied throughout Germany for preventing damage to the environment.  

 

 

Contact: 

Gummiwerk KRAIBURG GmbH & Co. KG 

Teplitzer Str. 20, 84478 Waldkraiburg, GERMANY

E-mail: info@kraiburg-rubber-compounds.com

 

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