Barium / Cadmium
Barium / Cadmium / Zinc  
 Barium / Zinc  
Calcium / Zinc  
Barium / Lead  

 

These are metal carboxylates which are mixtures of salts of aliphatic and aromatic carboxylic acids and sometimes of alkylphenols with Barium, Cadmium,, Zinc and Calcium in different proportions. Often stearic or lauric acid are used for solid, unsaturated or short-chain acids, alkylbenzoic acids as well as alkylphenols, for liquid systems.
Carboxylates are mostly used in combination. Barium compounds with Zinc or Cadmium compounds and Calcium with Zinc compounds, as these are synergistic thermo stabilizers. Cadmium or Zinc carboxylates give good initial color but poor long-term stability whereas Barium and Calcium compounds show the opposite behavior. Suitable combinations, e.g. Barium/Cadmium carboxylates or Calcium/Zinc carboxlyates provide good initial color together with good long-term stability.
Metal carboxylate stabilizers must be chosen which are appropriate to the PVC type, the numerous formulation variations, including the use of plasticizers and fillers and the processing techniques such as calendaring, extrusion, injection molding, plastisol processing. Additionally, the demands made to the end product, for example high transparency, weathering stability, resistance to discoloration owing to sulphur compounds, plate out and fogging control, ease of printing and welding must be considered. This is the reason why so many different metal carboxylate stabilizers are in the market, and why they are all dissimilar.