“Brighton is by far the most important technical conference in the PVC world. That’s why we decided to come with something really challenging for the flexible PVC markets,’’ says Daniel Martinz, Technical Marketing & Development for Paste PVC applications at SolVin.
“That is, assessing different bio-based plasticisers studied over the past two years as potential alternatives for current general purpose, or GP phthalates in paste PVC and in S-PVC applications, to help ensure the industry’s sustainability by moving away from petroleum-based compounds.”
The bio-based materials derive from the hardly exotic soybean oil, castor oil and starch.
“We took more than 20 renewable plasticisers from around the world and compared them with DEHP, DINP and DIDP. We zoomed on properties like efficiency, processability, rheology, volatility, thermal stability, water pick-up colour and foamability.
Replacing a GP phthalate is not an easy task. Aspects like economics (price and availability), performance (processability, long term compatibility and others) and toxicology have to be taken into consideration.
“Six years ago, when I received the first sample of a bio-based plasticiser in my lab in Brazil, I almost had a heart attack: it was awful”, teases Daniel. “But then these products start to quickly improve and one would be amazed at how some of them are really performing. The main problem is the limited availability of these plasticisers and, in some cases, the higher prices in comparison with GP plasticisers.”
Plasticisers are the most important additives for PVC; they are molecules used to increase flexibility, extensibility and workability of PVC by shielding polymer chains one from another. The most extensively used plasticisers are the GP phthalates, representing 87% of global consumption or 5.2 million tonnes a year. Among the GP phthalates, DEHP (di-2-ethylhexyl phthalate), DINP (di-isononylphthalate) and DIDP (di-isodecylphthalate) account together for more than 80% of worldwide demand. On the other hand, phthalates are 100% manufactured from fossil fuels (crude), which causes some issues in terms of carbon footprint and long-term sustainability.
Plasticised PVC today represents nearly 35% of all PVC applications, accounting for approximately 12 million tonnes of resin worldwide in 2010. In Western Europe the flexible vinyl business is roughly 1.3 billion euros a year (c.a. 1.4 million tonnes).
“These markets are highly dependent on the availability of plasticisers and cannot exist without these additives, especially the paste PVC applications, where plasticiser blending is required in basically 100% of cases”, says Martinz. “The PVC chain simply cannot afford a world without plasticisers. The natural conclusion is that bio-based raw materials are the key to assuring the long-term sustainability of these businesses.”
The new materials can contain from more than 65 percent to 100 percent renewables, he says.
‘’Results were really surprising and the conclusions were that plasticisers like Soft-N-Safe® (from Danisco SA), Polysorb® ID 37 (from Roquette Frères), Resiflex® K50 (from Resypar), PLS Green® 9 (from Petrom SA) and Kalflex 14OA (from Varteco SA) are promising alternatives to GP plasticisers, both in S-PVC formulations as in Paste PVC applications”, says Daniel.
He predicts that there’s plenty more R&D ahead.
‘’Our assessment took into consideration mostly the technical point of view and not the toxicological and commercial ones (prices and availability), aspects that play a major role in the choice of a given plasticizer,’’ Martinz says. ‘’The results are good, but this is definitely an unexplored road that might bring us surprises for the future.’’
Discover the presentations: Daniel Martinz & Luc Matthysen.
