PETpla.net Insider 05 / 2016

MATERIAL / RECYCLING 12 PET planet insider Vol. 17 No. 05/16 www.petpla.net PET is now in its 75 th year – and still revolutionising the drinks world 75 years and big in business by Gabriele Kosmehl The synthetic material polyethylene terephthalate this year celebrates its 75 th birthday. Originally developed as an alter- native to the manufacture of textile fibres, the material is today one of the most important in the packaging and textile industries. Since the start of the 1970s, PET has revolution- ised the drinks market. According to Krones, today every third drinks packaging in the world is a PET bottle, more than 500,000,000,000 bottles. The year is 1941. In the labora- tories of the textile company Calico Printers Association in Accrington, UK, the Englishmen John Rex Whin- field and his assistant James Ten- nant Dickson produced a polyester from ethylene glycol and terephthalic acid. The material was intended to serve for the production of robust and cheaper textile fibres, as an alterna- tive to Japanese silk and nylon. As the patent came during the Second World War, the invention was initially clothed in secrecy. The British chemical com- pany ICI, asked by the British govern- ment to carry out further research, started a trial production of PET fibres in 1949, under the brand name “Terylene“. The production rights for the USA were acquired by DuPont. DuPont later branded the polyester fibres as “Dacron.” Triumph with the bottle format In 1967 Nathaniel Convers Wyeth, who joined DuPont in 1936 as a field engineer, asked himself whether the very popular carbonated soft drinks that came in heavy glass bottles could be stored in plastic bottles. After experimenting at home with a plastic detergent bottle that proved incapable of withstanding the forces of pressur- ised liquids, he realised that a much stronger material would be required. He initially experimented with polypro- pylene and transferred his knowledge about stretching polyamide 6.6 to PET. After thousands of attempts he succeeded with PET as the material, using compression-moulded preforms, and obtained the patent in 1973. From then on, PET could be transformed into strong but lightweight bottles. Also in 1973, Bill Gaiser, Founder of Broadway Industries, designed and built the first injection mould to pro- duce a PET preform, and then used it to produce the first injection-moulded PET preform in the world and devel- oped the process even further during the following years. Now that the pre-requisites had been set, Pepsi and Coca-Cola in particular set about conquering the world with the PET bottle. Since the 1960s both companies had been repeatedly trying to put their drinks into plastic bottles. There had been numerous tests with various types of plastic for the first PET bot- tles, of which only polyester and nitrile proved to have the neces- sary physical characteristics. Whilst nitrile proved to be unsuitable for contact with foodstuffs because of its toxicological characteristics - a plastic bottle with a high nitrile con- tent launched by Coca-Cola in 1975 had to be withdrawn from the market because of health concerns - PET crystallised during processing and at high temperatures became cloudy. Wyeth’s invention solved these prob- lems and PET bottles came onto the market quickly and in great numbers. Pepsi and Coca-Cola were pioneers in filling CSDs into PET bottles and in 1977 (Pepsi) and 1978 (Coca- Cola) launched 2 litre bottles onto the market. The PET plastic bottle soon became popular for numer- ous reasons: it does not break, it is re-sealable; it is lightweight and it is recyclable. One of the very first PET bottles for CSD (photo: Coca Cola)