Mixed metal oxide pigments
The demand on finished products to have an ever longer durability and superiority in terms of quality, as a consequence, leads to increasing requirements on durable pigments used for the colouring of products such as paints and lacquers, plastics, building materials and ceramic products simultaneously.
HEUCODUR® mixed metal oxide pigments have been developed to meet these increasing requirements on quality, in particular, considering ecological aspects. This pigment class is extraordinary among the colouring matters as they are chemically inert while featuring high light and weather resistance and chemical stability. The exceptional fastness properties are based on the fact that homogeneous mixed metal oxide pigments are created in a high temperature process, i.e. at a temperature in excess of 800°C. HEUCODUR® pigments qualify for both all types of coatings (with the exception of printing inks) and the colouring of plastics, ceramics and mineral/cementitious products.
Manufacturing process of mixed metal oxide pigments
Rutile and spinel pigments are manufactured in a solid state reaction of fine particle metal oxides, hydroxides or carbonates at temperatures from 800 to 1200°C. The burning process is either accomplished continuously in a cylindrical rotary or tunnel furnace or discontinuously in a directly fired trolley hearth kiln or barrel-shaped furnace. The calcination is followed by grinding in order to ensure the coloristic properties desired and an easy application for the end user.
Application: coating materials
Owing to slightly purer shades rutile pigments offer the benefit of an even wider range of coloristic options compared to iron oxide pigments. Rutile pigments are characterized by their insolubility, the high level of chemical and thermal resistance, and an excellent light and weather fastness. They especially qualify for air-drying systems and stoving enamels as well as coil coatings and powder coatings. Another field of application are aqueous and solvent-containing façade paints.
These products allow a wide range of shades in combination with high-quality organic yellow or red colours. In this case, the rutile pigments provide for the required hiding power while the combination with organic pigments enables obtaining the required brilliance.
As one of the spinel-type pigments, cobalt blue features excellent fastness properties. The outstanding chemical resistance and the excellent weather fastness, even in extreme reductions with titanium dioxide, are particularly worth mentioning. Fields of application are, e.g., coil coatings, powder coatings, swimming pool paints and foils.
Application: plastic materials
The generally high level of resistance to aggressive chemicals and solvents as well as the high migration fastness should be pointed out here. Even in large-scale injection moulded and extrusion parts made of plastics they are non-warping so that they especially suit, for example, the colouring of bottle cases.
Application: building materials
Due to their high resistance to light, weather and alkali, the mixed metal oxide pigments are absolutely suitable for applications in the building industry. Above all, nickel titanates are widely used in the field of plasters, even if smaller quantities are concerned, because of their brilliant shade. Cobalt blue pigments can be recommended for the colouring of blue grout, paving stones and gypsum without any restrictions. Unfortunately, a comparatively high price of the products often does not allow a large-scale use of the same.