Yellowing of textiles due to atmospheric pollutants

Organic polymers often develop yellowish colours as they age. the result of oxidative or degradative processes. Improvements have been made in methods of manufacture and in development of stabilizers to reduce the effects of ageing. This kind of yellowing is unlikely, therefore, to explain the increase in the severity of the problem. When fluorescent brightening agents (FBAs) were introduced, there were instances of yellowing due to the effects of light, of acid, of impurities, or even of concentration. Here too, there have been improvements in the quality and the colourfastness of the compounds used. This type of yellowing is therefore also unlikely to be the principal factor in the problems of the past few years. However, P BAs used in processing in some parts of the world can be of lower stability than the materials used in the UK textile industry. During the period in question there has been a considerable increase in the use of phenol and aromatic amine antioxidants and stabilizers in many commonly available products, e.g. packaging, lubricants and other auxiliaries, foams, elastic and rubberized materials. There has also been an increase in the level of atmospheric pollution, with oxides of nitrogen in areas close to high density of traffic and to gasor oil-fired lieating systems. The resulting yellow products not only cause discoloration, but also quench the fluorescence of white textiles containing fluorescent brightening agents. The number of cases of yellowing of textiles sent to Shirley Institute for investigation has also increased over' the same period. During the past two years the distribution of causes has been as shown in Table i. By far the