PVC Stabilisation
technical bulletin
No.5
Polyvinylchloride (PVC) is a material that can - when
combined with appropriate additives - be used to form
finished products as diverse as:
·
flexible and rigid medical devices
·
electrical cable insulation and sheathing
·
rigid and flexible pipes
·
foam and window profiles
As such, PVC is one of the most versatile and industrially
important plastic materials around today :
(www.bpf.co.uk/bpfgroups/Vinyls_Groups.cfm)
The combination of PVC and the required additives is normally referred to as a PVC compound. One of the more
important additives used in all PVC compounds is the PVC stabiliser. As PVC stabilisers are not an every day topic and
there are different, complicated chemical technologies available, it is not surprising that there can be some confusion
concerning stabilisers and PVC. This Technical Bulletin seeks to clarify the situation by answering these simple questions.
·
·
What is a stabiliser in PVC and what does it do ?
What are the different stabiliser technologies available and are there any issues surrounding these technologies ?
What is a stabiliser and what does it do ?
PVC is a thermoplastic material - it requires heat in order to soften and allow it to be formed into a desired shape,
usually by extrusion or injection moulding, following which it is cooled to maintain that shape. Unfortunately, by itself
the PVC molecule breaks down and degrades when heated to the required softening temperature and this degradation
results in a discoloration of the product and ultimately in a loss of physical properties. The primary purpose of a
stabiliser in a PVC compound is, therefore, to protect the molecule when it is being heated in the manufacturing process
and allow the desired shape to be formed whilst maintaining appearance and physical properties. Stabilisers can also
work in conjunction with a number of other additives in the PVC compound such as Titanium Dioxide to combat the
long term effects of weathering (i.e. also discolouration and loss of physical properties).
What are the different stabiliser technologies available and what are their issues? (www.stabilisers.org)
Currently in the UK and Europe there are three main stabiliser
technologies widely used in PVC-U extrusions (unplasticicised
PVC typically used for window profile and other building
products) and PVC-UE extrusions (unplasticised, expanded
or cellular PVC typically used for fascias, soffits, cladding and
other building products); These are lead, tin and calcium
organic.
The latest enviromental and legislative developments as the
affect PVC stabilisers are Vinyl 2010, The Marketing and Use
Directive 76/679 EEC and REACH.
Billet Lane, Normanby Enterprise Park,
Normanby Road, Scunthorpe,
North Lincolnshire, DN15 9YH
Tel: (01724) 400440 Fax: (01724) 280241
Email: [email protected]
www.kbp.co.uk
PVC Stabilisation
technical bulletin
No.5
Vinyl 2010
This is the European PVC industry's 10-year Voluntary Commitment for sustainable
development and product stewardship across the life cycle of PVC (www.vinyl2010.org).
Vinyl 2010 contains a number of commitments against key criteria, the main one related to
stabilisers being a reduction in lead stabiliser consumption from 2000 levels by 15%, 50% and
finally 100% by 2005, 2010 and 2015, respectively. In 2008, European Stabiliser Producers
Association (ESPA) members were able to report that lead stabiliser use in the EU-15 had
reduced by over 50% since 2000, some two years ahead of the 2010 interim target. ESPA also
reported that this reduction has been achieved through a switch to calcium-based (i.e. calcium
organic) stabilisers. No targets for tin or calcium organic stabilisers are included in Vinyl 2010.
The Marketing and Use Directive 76/769 EEC
Under this Directive, DiButyl Tin (DBT) stabilisers of the type used by a number of PVC-UE profile manufacturers will
be banned in articles for supply to the general public containing greater than 0.1% by weight of tin by January 1st
2012, or by derogation in some applications by January 1st 2015. In practice it is by no means clear if all roofline and
window trim products fit in the former or the latter of these bans.
DiOctyl Tins (DOT) stabilisers of the type some producers appear to be using to replace DBT, at least in the cellular
core, are also subject to restrictions under Directive 76/769 EEC (See - Official Journal of the European Union - L
138/11). After 1st January 2012, these too will be banned from certain products that come into contact with skin,
including childcare articles and wall coverings and this could include cladding.
REACH (Registration, Evaluation and Authorisation of CHemicals)
Is the EU regulatory framework for the management and control of chemicals. This is a huge undertaking managed
by the European Chemicals Agency (ECHA) and the exact outcome of the REACH process for each and every chemical
manufactured and used in Europe is not known in advance. However, there is an increasing understanding of the
likely outcome in many cases (www.echa.europa.eu).
Since DBT is Category II Carcinogenic, Mutagenic or Reprotoxic (CMR) a registration document must be presented
to ECHA by the end of November 2010. The production of this document, which includes a safety report, is an
expensive process. Hence, in light of the deadlines in Directive 76/769 EEC and the volumes involved, it may not make
commercial sense for companies to register these products. Thus the combination of REACH and Directive 76/769 EEC
mean that most, if not all, of these stabilisers may not be able to be manufactured after November 2010, irrespective
of these deadlines.
Lead stabilisers (Category I CMR) also require a registration document by the end of November 2010. In this case
a combination of existing safety reports and higher volumes mean that it is likely to make commercial sense for
companies to register the main lead stabilisers. Currently it appears that the Industry's voluntary commitment on lead
(see Vinyl 2010) and the progress made to date in reducing the consumption thereof, is such that the sunset date for
lead stabilisers under REACH is likely to be around 2015, and therefore in line with Vinyl 2010.
DOT stabilisers (Category III CMR) with production volumes greater than 1000 mtpa will also require a registration
document by the end of November 2010. It is currently unlikely that these will be subject to authorisation under
REACH.
The components that make up commercial calcium organic stabilisers are either exempt from REACH (See annex 4
and 5 of REACH) or are not likely to be subject to authorisation under REACH.
Billet Lane, Normanby Enterprise Park,
Normanby Road, Scunthorpe,
North Lincolnshire, DN15 9YH
Tel: (01724) 400440 Fax: (01724) 280241
Email: [email protected]
www.kbp.co.uk
PVC Stabilisation
technical bulletin
No.5
Why Calcium organic?
Traditionally in Europe calcium organic stabilisers have been used in applications such as
food, medical and pharmaceutical packaging and bottles for mineral water. They are now
the preferred choice for pipes and cables and, as lead replacement by calcium organic
continues under Vinyl 2010, calcium organic stabilisers will also become the stabiliser of
choice for profiles, including windows. European production volumes of calcium organic
stabilisers were slightly more than lead and five times that of tin stabilisers in 2008 (www.
vinyl2010.org ; See Progress Report 2009 - Page 6 and 23) a position that is likely to
continue to strengthen. Hence, calcium organic stabilisers are clearly now the main PVC
stabiliser by volume in Europe and the stabiliser of choice for rigid PVC building products in
general.
It is worth noting that some European window profile producers have based their production on calcium organic
stabilisers for almost 20 years with excellent results and proven weathering performance. One of the issues with DOT
stabilisers as a replacement for DBT in external applications is the relatively little experience and natural weathering
data that exists on colourfastness of these products in external building products in the UK.
Meeting Legislative commitments on stabilisers, whilst important, is only part of our industry's approach to
sustainable development under Vinyl 2010. Other important considerations are the consumption of energy, water
and raw materials during manufacture and the ability to recycle post industrial and post consumer waste. As
with all PVC formulae and all stabiliser types, performance depends on the combination of correct processing and
formulation. Since, moving to calcium organic stabilisers our business has continuously reduced like-for-like resource
consumption and have successfully processed significant quantities of material with high quantities of rework in the
core, and any scrap from this process has also been reprocessed at the same high level. We reprocess any scrap inhouse and do not send any in-process scrap to landfill. The other significant environmental benefit of using calcium
organic stabilisers in PVC, unlike for example lead or tin stabilised product, is that they don't have adverse interactions
with most, if not, all other formulae. So when mixed end-of-life post consumer waste starts to become more available
in years to come, calcium organic will be the most flexible platform for recycling. To summarise, calcium organic
stabilisers:
·
Are not included in any restrictions or bans resulting from Directive 76/769 EEC
·
Will be REACH compliant
·
Are the major stabiliser by volume for PVC in Europe
·
Are the major stabiliser in building products in Europe - a position that will only strengthen as the impact of Vinyl 2010 continues apace
·
Can be successfully recycled forming a versatile platform for PVC waste recycling of all types in the future.
Issue 2: 15 January 2010
To Guarantee Kestrel Calcium Organic Stabiliser ....... Look for the logo
Billet Lane, Normanby Enterprise Park,
Normanby Road, Scunthorpe,
North Lincolnshire, DN15 9YH
Tel: (01724) 400440 Fax: (01724) 280241
Email: [email protected]
www.kbp.co.uk