Quench - APY(2009-2010)

Anti Phenolic Yellowing

Causes of yellowing during storage The intensive yellowing of white or pastel colored textile good is very often a result of the presence of phenol-based antioxidants (butylated hydroxyl toluene derivates). This chemistry is low in cost and highly effective. Due to its low vapor pressure it is volatile and can be transferred to textile goods easily. Products of this type are commonly used as stabilizers in Fibre production, Further textile processing.Packing materials (e.g. polyethylene wrapping films, packing material in general) 

Mechanism Of Yellowing

Factors influencing the yellowing Various factors influence the yellowing of white textile goods in presence of antioxidants :  Storage conditions

Atmosphere composition in store, shop and home(NOX beside other pollutants)

Humidity and temperatureHeating and ventilationStorage timeIllumination

 Composition of hot air, particularly on drying / curing/ heat-setting equipment with direct gas heating when nitrogen oxides are produced due to unproper burning conditions.

Precautions lowering the risk of yellowing •As long as such antioxidants are used it is virtually very difficult to prevent such yellowing. To reduce this yellowing we recommend :  •Warn customers to ensure that fibres and auxiliaries are free of phenolic antioxidants. Especially packing or wrapping materials should be free of antioxidants (phenol free low density polyethylene bags) • Adjust the final finish with some non volatile organic acid (shade and optical brightener should be acid stable). •To avoid the presence of nitrogen oxides (NOX) during production and storage (no direct gas heat, all transportation systems such as fork-lift trucks with electric motors, good ventilation in warehouse to avoid air pollution).

Normally white PA turn yellow even under slightly acid conditions. This is due to the cationic character of the free amino end-groups of PA which interact with the antioxidant derivates. Quench APY is preventing such yellowing while blocking the free amino end-groups of the PA. For the application in general we recommend to use slight acid conditions. Please check also whether the optical brightener is acid stable if non-volatile acids are used.      

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