PETpla.net Insider 06 / 2019

13 PET planet Insider Vol. 20 No. 06/19 www.petpla.net JUBILEE A review of PET bottle developments The evolution of the PET bottle “Excellent strength properties, impact resistance, and capable of holding liquids under pressure” were the main characteristics with which Nathaniel Convers Wyeth and Ronald Newman Roseveare, both of DuPont de Nemours and Co, have described their invention on the manufacturing of a PET bottle. For this, they were granted US patent US3733309A on May 15, 1973. Whilst the features may not have changed all that much, various developments in materials, design and processing have resulted in constant improvements in PET bottle production. Some of these are highlighted in our 20-year review. Patent specification “Biaxially oriented Poly(ethylene Terephthalate) bottle” as filed on November 30, 1970 When Wyeth and Roseveare regis- tered their patent in 1970, PVC bot- tles, which were mainly used for still water, were already starting to appear on the market alongside glass bottles and cans. Wyeth, who joined DuPont in 1936 as a field engineer, was also looking for a plastic solution for carbon- ated drinks and began experiment- ing at home. After initial unsuccessful attempts to withstand the forces of pressurised liquids, he realised that a much stronger material would be required. He experimented with poly- propylene and transferred his know- ledge about stretching polyamide 6.6 to PET. After thousands of attempts he succeeded with PET as the material, using compression-moulded preforms. Machine manufacturers such as Heidenreich and Harbeck from Hamburg and Milacron from the USA brought their skills and expertise to the processing side of things. The former had already been develop- ing a high-performance rotary unit for stretch-blow moulding of PET bottles as early as May 1971. Bill Gaiser, Founder of Broadway Industries, designed and built the first injection mould to produce a PET pre- form, and then used it to produce the first injection-moulded PET preform in the world and developed the process even further during the following years. Now that the pre-requisites had been set, Pepsi and Coca-Cola in par- ticular 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 bottles, of which only polyester and nitrile proved to have the necessary physical characteris- tics. Whilst nitrile proved to be toxi- cological for food contact and hence unsuitable, PET crystallised during processing and at high temperatures became cloudy. Wyeth’s invention solved these problems and PET bot- tles came onto the market quickly and in great numbers. Pepsi and Coca-Cola were pio- neers 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 numerous reasons. As Wyeth’s patent speci- fication states, the bottles’ strength properties were excellent. They offer impact resistance and are capable of holding liquids under pressure. The fact that the bottles were re-sealable and recyclable, as well as becoming increasingly lighter over a great many years, may also have contributed to their tremendous success. Today, around 80% of the PET resin market contributes to the bottle production process. Water takes up the largest share, followed by CSD. However, sensitive beverages are being increasingly filled in PET bottles worldwide. According to Euromonitor, Liquid Dairy Products in PET bottles are predicted to grow by 9% over the period 2018-2022. In addition to being filled with drinks, the PET bottle is also playing an increasingly important role in the home and personal care sectors. 2017 2018 growth in % World 246,081.50 260,838.30 6.0 Asia Pacific 98,702.50 106,838.60 8.2 Eastern Europe 12,641.40 13,676.80 8.2 North America 57,096.60 59,198.00 3.7 Western Europe 41,727.30 43,867.30 5.1 Global and per regions PET bottles for bottled water in million units, and its year on year growth in percentage from 2017 to 2018 (source: Market research provider, Euromonitor International) PET bottles – some high- lights 1999 to 2019 as reported in PETplanet Insider 1999 Schmalbach announced a hot fill bottle that could be filled at up to 85 °C. 2000 PLM, in issue 1 of 2000, presented the first refillable PEN bottle for beer. It could be rinsed with hot water at 75 °C. In issue 8 Owens Illinois announced that Coors was testing their 16-ounce beer bottle.