Лако-красочные материалы — производство

Notwithstanding that most inorganic pigments have been known for a very long time, new developments appear on the catwalk of colors. The so-called “high performance pigments” [1.1] show a lot of modern developments.

Driven by environmental laws, even some of the former important inorganic pig­ments have had to be replaced. For example, red lead was fully substituted in most countries in anticorrosion paint. However environmental considerations are not the only driving force in the development of new pigments. The invention of new pig­ments and the improvement of the already existing pigments in this class in the last decade have made new color effects available on an industrial scale (see Section 5.3). New physical effects led to the so-called “quantum effect pigments”, but these are in the very early stage of nanoscale laboratory curiosities.

The progress in multi-component mixed crystal systems shows lanthanum-tantalum oxide-nitrides as promising candidates with interesting color shades in the red to yel­low range [1.2, 1.3] but the development into industrially available pigments has yet to be proven. Even the promising candidate of the last decade, cerium sulfide [1.4], presently available in technical quantities, is still waiting for its breakthrough because of stability problems, which have not yet been resolved [1.5].

The reasons for the slow introduction of new pigments may be that the regulatory hurdles for newly introduced chemicals are high, and also that customers are making more demands on the performance of new materials and the Three Essential E’s: Effectiveness, Economy and Ecology.

There are still challenges: Brilliant, inorganic, nontoxic, stable and cheap green or blue pigments are amongst these. Probably, the mixed crystal systems are promising fields for new discoveries.

The general areas for the development of inorganic pigments that are new or already on the market can be summarized as follows [1.5]:

1. Many pigments are coated with an additional layer, having no strong influence on the color, but improving the application properties: better adjustment of pigment and binder components (pre-wetting of the pigment surface, disper­sion behavior, settling behavior, etc.); improved weathering properties of the pigments in the binder system (i. e. stability against UV, humidity, etc.). These surface treatments (aftertreatments) can consist of inorganic (SiO2, Al2O3, ZrO2), organic (polyalcohols, siloxanes, organo-functional silanes or titanates) or combined inorganic/organic compounds.

2. The pigments are offered not only as pure, free-flowing powders, but also in the form of preparations (granulates, chips, pastes, color concentrates). These preparations contain the pigment in as high as possible concentration. In addition to the pigment, the preparations consist also of binder components or binder mixtures based on solvent and waterborne systems. Such pigment- binder combinations show certain advantages for the users of paints, printing inks or plastics (i. e. better pigment dispersibility, non-dusting introduction of the pigment in the application system, optimized wetting behavior, improved coloristic effects in the final products).

3. New approaches are being made combining the high hiding power and stability of inorganic pigments with the brilliance and saturation of organic pigments. Besides the known simple blending (e. g. “iron green” = yellow iron oxide hy­droxide with phthalocyanine) new preparations of specialized titanium dioxide with high performance organic pigments show interesting properties, but the proof of merchantable quality is yet to come.

The further development of tailor-made surface treatments and pigment prepara­tions will lead to the faster introduction of new applications for inorganic pigments in the future.

1.2