What are softeners? What are phthalates and why are phthalate-free softeners needed?
Softeners are substances that are added to brittle materials to make them soft, flexible or stretchable, so that they are easier to work with or achieve specific properties. Phthalate-free plasticizers serve as environmentally friendly substitutes for phthalates.
Only the addition of softeners gives the intrinsically hard and brittle plastic polyvinyl chloride (PVC) elastic properties – and thus enables applications as soft plastic. Softeners should also have a number of properties, such as being light, temperature and water resistant, odourless and colourless, flame-retardant, low volatility and of course not harmful to health. They are contained in large quantities in plastics, paints and varnishes, paints and coatings, sealing compounds, rubber and rubber articles and adhesives. Softening substances also play a role in textile finishing to improve the feel and suppleness. About 35 percent of the raw PVC produced is processed into flexible PVC (PVCplus 2005)
What are phthalates?
Phthalates are compounds of phthalic acid (1,2 benzenedicarboxylic acid) with various alcohols (phthalic acid esters). Phthalates are mainly used as plasticizers for plastics. It is only when they are added that polyvinyl chloride (PVC), which is hard and brittle in itself, acquires elastic properties and enables it to be used as a soft plastic. The chemical industry in Western Europe produces around one million tonnes of phthalates annually. They are used, for example, in cables, foils, floor coverings, hoses, wallpaper, sports and leisure articles. More than 90 per cent are used as plasticizers in the production of soft PVC (ECPI 2006). Products made of soft PVC consist on average of 30 to 35 percent plasticizers (AGPU 2006).
Why phthalate-free softeners?
Phthalates are released into the environment when they are used and, if they are only slowly degraded, they enter the food chain as a result. They can then be ingested to a significant extent with food. Direct absorption through the skin is only pronounced in the case of short-chain phthalate esters; in the case of the other phthalate esters it is of minor importance in humans.
The industry uses very different substances as softeners, with low-volatile phthalic acid esters still predominant in terms of quantity. The five most commonly used phthalates are: DIDP (di-iso-decyl phthalate), DINP (di-isononyl phthalate), DEHP (di(2-ethylhexyl) phthalate), DBP (di-butyl phthalate) and BBP (benzyl butyl phthalate).
The member states of the European Union (EU) classified the phthalates DeHp, DBp and BBp as toxic for reproduction. A risk to humans or the environment results from the risk assessments in only a few areas of application – for example, baby articles and children’s toys. The EU Commission has now issued a ban on use in these areas. For some years now, the chemical industry has been replacing phthalates that are toxic for reproduction, primarily with DIDP and DINP, which are not classified as hazardous substances. For DIDP – and for precautionary reasons also for DINP – there is nevertheless a ban in Europe on baby products and children’s toys that can be put in the mouth.
In 2004, the market share of non-phthalate softeners in Western Europe was about seven percent (AGPU 2006). These are mainly adipates (esters of adipic acid), especially di(2-ethylhexyl) adipate (DEHA) and diisononyl adipate (DINA), and citrates (esters of citric acid), especially acetyltributyl citrate (ATBC). Phosphates with simultaneous flame-retardant effects also act as plasticizers. DEHA is mainly found in food packaging, the somewhat more volatile DINA mainly in floor coverings and vinyl wallpaper. ATBC is mainly used as a substitute in children’s toys made of soft PVC. These non-phthalate-containing plasticizers have environmental advantages over phthalates in terms of their ecotoxicological and toxicological properties.