UPVC was produced for the first time in 1935 and has been industrially manufactured in large quantities for over 50 years. It has been developed into a material that offers a wide range of properties. The process starts with sodium chloride (common salt), from which chlorine gas is obtained by electrolysis. Petroleum or natural gas is used to produce ethylene, one of many products of the process known as ‘cracking’. Bringing together chlorine, ethylene, and liquid vinyl chloride.
The letters PVC stand for polyvinyl chloride, which is a chemical compound of chlorine, carbon and hydrogen. The components of PVC originate from the naturally occurring raw materials of petroleum or natural gas and common salt. The U stands for unplasticised (sometimes called unmodified), and it means that the material has not been softened by the addition of chemicals known as plasticisers. PVC-U is based on the polyvinyl chloride, to make the material suitable for use as a window a number of different additives and stabilisers are used. These special heat and UV stabiliser additives are an essential part of any PVC formulations used for the manufacture of PVC-U windows. Because windows are exposed to the elements, including wind, rain and UV light, some superficial changes can occur. There would be no loss of impact strength or structural integrity and the colour would also remain white.
The first commercially available windows were installed in Germany in 1959 and some of these earlier PVC -U windows are still in use today. The technology for producing these windows has advanced over the years with the introduction of better performing acrylic-based impact modifiers.
PVC-U has been used in the fabrication of windows and doors for around 40 years on the continent with great success and for around 25 years in this country. It is an excellent, highly insulated material, which benefits from little or no external maintenance. It is readily available, well tested and mainly seen in white but also available in Irish Oak, Cherrywood and Rosewood woodgrain styles.