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What Is Ca Zn Stabilizer
Aug 02, 2017

Calcium - Zinc stabilizers

The use of calcium/zinc stabilizer systems has been common in PVC applications for over 25 years.

These materials are generally based on metal carboxylates and will sometimes incorporate other elements to boost performance such as aluminium or magnesium. Because the heat stability in some applications may require some enhancement when using calcium/zinc, organic co-stabilizers will also often be added to this type of formulation. These materials include polyols, epoxydised soya bean oil, antioxidants and organic phosphites.

Properties and Applications
Because of the characteristics of calcium/zinc stabilized materials they are widely used in many flexible and rigid PVC applications. This type of stabilizing system can give products which have a high degree of clarity, good mechanical and electrical properties, excellent organoleptic properties and good outdoor weatherability. As a result, calcium/zinc stabilizers have been incorporated and established in a wide range of applications as shown in table two. These include toys, healthcare products, such as blood bags, semi-rigid and flexible foil for food packaging, bottles for potable water, as well as for potable water pipe.

The performance of more recent developments in calcium/zinc stabilizers also makes them potential technical alternatives to most other stabilizing systems, including lead and barium/zinc. As a result of the European PVC industry’s commitment to progressively phase out heat stabilizers based on lead compounds, considerable development work has been carried out on new, improved systems for applications including cable covering, pipe and window profile and many of these are have been in commercial use for several years. These newer forms of calcium/zinc stabilizer are in general more complex and expensive than the traditional soaps mainly because of the specialized co-stabilizers required to meet the specific requirements of these applications. The rate of introduction of such stabilizing systems was slowed down by the extensive evaluation work required and the need for acceptance by the specifier. So far, the penetration of calcium/zinc stabilizers in these three sectors is complete in drinking water pipes and cables but not yet in other pipes and profiles. Sales of formulated Ca based stabilizers in Western Europe and Turkey , including Ca/Zn, have increased from 18 kt in 2000 to 80 kt in 2011. Further growth is expected as a result of the progressive phasing out of lead-based systems. In the sector of flexible foils where the main stabilizer used is a barium/zinc soap, substitution by calcium/zinc materials is also taking place although, again, there are technical issues which need to be overcome.

Applications for stabilizers - European Market


stabilizer Type

 Application

Pb 

 Pb/Ba/Cd

 Ba/Cd

Ca/Zn 

Ba/Zn  

 Sn

K/Zn (2) 

 Unplasticised PVC







 Pipes

 ++



++(1)




 Fittings

 ++





 +(1)


 Profiles

 ++

++


+




 Foil






++


 Bottles




++


++


 Sheet

 +



(+)


++


 Plasticised PVC








 Cable Covering

 +



++




 Foil and Sheet

 +


 +

++




 Flooring





 ++

+

++

 Wall Covering




 (+)

++

+

++

 Medical Use




 ++




 Tubes and Footwear




 +

++



 Food Packaging Film





 ++



 Fabric Coating




 +

++


++

++ Major use + Minor use (+) Occasional use (1) Used for potable water pipe (2) Used as a stabilizer/'kicker' for foamed layers in these products

Safety, Health and Environmental Issues
Inherently calcium/zinc stabilizer systems incorporating the proven range of co-stabilizers have low toxicity or are regarded as non-toxic.
Calcium/zinc salts of any of the acids in the EU Additives Directive are approved for food contact use, although specific approval would depend on the co-stabilizer incorporated into the stabilizing system. Solid calcium/zinc stabilizers have to meet the general requirements for dust emissions in the workplace although dust-free forms are readily available. Zinc is an essential element to human activity and health and has been the subject of various risk assessments. The conclusion of these has been that there are no risks to human health or the environment arising from the use of zinc stearate in PVC heat stabilizers.