Читать книгу Additives for Water-borne Coatings - Wernfried Heilen - Страница 6

Frank Kleinsteinberg

Dispersing of pigments is indisputably one of the most demanding steps in the manufacture of coatings. Formulators therefore look for easy solutions and additives that fulfil a number of different demands.

Already the first step in pigment dispersing – wetting of the pigment surface, which can have a very low energy – is highly problematic because the high surface tension of water needs to be reduced, without creating too many side effects. Even more problematic is finding the right stabilisation mode to match the water-borne binder. Finally, the pH also plays a key role in pigment wetting, stabilisation and compatibility.

Meeting these complex demands calls for combinations of additives that have different functions. Where applications require outstanding performance by all components, modern, highly sophisticated wetting and dispersing additives are used. The mode of action of wetting and dispersing additives at the various stages of pigment grinding is explained below. Various chemical concepts are elucidated in terms of performance and regulatory constraints and their significance for specific market segments is examined.