Speakers at the recent PVC Formulation conference discussed new stabilizer
developments for a wide range of vinyl applications including profiles, pipe, sheets and foamed products
Seeking stability
Stabilizers play a critical role in PVC com- pounds, protecting the resin from degradation during polymerisation and processing as well as throughout its working life. They were the subject of a special session at AMI’s PVC Formulation 2012 conference, which took place in March in Düsseldorf, Germany. Leading suppliers of such additives gave updates on their latest developments for a range of applica- tions including flexible sheets, rigid profiles and foamed products. Baerlocher provided an update on
formulation trends in window profile extrusion. According to the company, approximately 2.5 million tonnes of PVC window profiles were produced in Europe in 2010, with Turkey emerging as the leading produc- er with a total of 590,000 tonnes. It was ahead of Germany with 580,000 tonnes and Russia with 443,000 tonnes. The big trend in stabilizers for such applications in
Europe has been the on-going phase out of lead stabiliz- ers. Under the Vinyl 2010 initiative, the industry made a voluntary commitment to end the use of lead-based stabilizers by 2015 in the 27 EU countries. An interim target of a 75% reduction in the use of such stabilizers between 2000 and 2010 has already been met, with calcium organic products being the main replacement. Baerlocher estimates that the ratio of lead-based to calcium-based stabilizers used in western Europe in
2010 was 30:70. The corre- sponding ratio for the whole of Europe, including Russia and Turkey was 50:50. This compares to 97:3 for Asia including China, and 93:7 for the Middle East and Africa. Lead is also still widely used in South America, where the ratio is 80:20, but the North American market is domi- nated by tin-based stabilizers. Looking at specific formulations,
Baerlocher highlighted the requirement for organic co-stabilizers alongside inorganic stabilizers in one-pack systems for white PVC
profiles. The co-stabilizers provide thermo-stability plus early colour and colour hold. The other elements of the one-pack typically include processing aids, external and internal lubricants, plus metal soaps. For brown profiles, there is a reduced requirement for
co-stabilizers in the one-pack system as dark colours do not require a low b-value and are not sensitive to b-value drift. This means that cost savings can be made. For plants producing both white and brown profiles, it may be advantageous to use the same base stabilizer for both colours and add a booster for the white products. For example, the base stabilizer could be selected from Baerlocher’s range of Baeropan one- pack systems, while the booster for white formulations