for example ethylene glycol propylene glycol butylene glycol diethylene glycol triethylene glycol dipropylene glycol tripropylene glycol polyalkylene glycols such as polyethylene glycol 1 4 cyclohexanedimethanol 1 4 cyclohexanediol pentanediol hydrogenated bisphenol a 1 3 propanediol 1 4 butanediol 1 6 hexanediol neopentyl glycol neopentyl glycol hydroxypivalate trimethylolpropane trimethylolethane glycerol erythritol pentaerythritol trimethylolbenzene or trishydroxyethylisocyanurate and mixtures thereof preferred components a2 are trimethylolpropane and glycerol optionally in combination with diethylene glycol or neopentyl glycol suitable monocarboxylic acids a3 are short chain or aromatic monocarboxylic acids such as for example benzoic acid tert butylbenzoic acid hexahydrobenzoic acid or 2 ethylhexanoic acid monocarboxylic acids which contain constituents having double bonds that are capable of oxidative crosslinking with atmospheric oxygen examples being soya oil fatty acid safflower oil fatty acid tall oil fatty acid fish oil fatty acid tung oil fatty acid linseed oil fatty acid and or sunflower oil fatty acid and also semi drying or non drying fatty acids such as for example castor oil fatty acid coconut oil fatty acid or peanut oil fatty acid it is preferred to use exclusively drying fatty acids such as soya oil fatty acid or sunflower oil fatty acid for example the stated fatty acids capable of oxidative drying such as soya oil fatty acid for example as a general rule depending on origin and year of harvest contain mixtures of different more or less unsaturated fatty acids and also saturated fatty acids in fluctuating compositions for simplification fatty acids of this kind with relatively high fractions of fatty acids capable of oxidative drying are always considered as being 100 capable of oxidative drying u2014 that is of crosslinking.