New method for producing non-toxic and biodegradable nanopigments
This method has two stages: 1) Dispersion of, at least, an inorganic material in water. 2) Addition of, at least, an organic coloring solubilized by agitation. The following parameters might be changed in order to obtain different kinds of nanopigments: • Inorganic material concentration. • Organic coloring concentration. • pH. • Temperature. • Ionic strength. The optical response of nanopigments changes as a function of the particle size of the inorganic material (or materials) used by the diffusion. This method makes it possible to produce new hybrid nanopigments with optical and colloidal properties for tailored applications. Mainly, the customizaton of the behaviour of this materials is achieved by controlling organic/inorganic ratio in the material. The morphology of the material is hybrid (laminar/fibrillar). The organic coloring is selected among different types: azoic complexes, metallic, sulphurose, iminoquinone, antraquinone, ftalocianine, etc. In general words, they can be both natural or synthetic. Products can be used in printing inks, painting and dyes, paper, synthetic or natural fibers, polymer materials, cosmetics, etc. With this method the following features can be achieved: Color range control: Through the control over the different spectral species, the optical response is modified too, so the color range can be enlarged. Increase in the colouring power: The ability of the material for increasing the absorption on the surface is linked to three parameters. First, absorption coefficient of the nanopigment in relation to the coloring solution coefficient. Second, light dispersion caused by nanoparticles and addtiional coverage of the surface to fill. Third, reology and fisico-chemical properties of the material are able to obtain homogeneous dispersions. Environmental impact reduction: Some of the usual pigments contain heavy metals in its composition while inorganic solids used in this method are free of heavy metals and can even be used in cosmetics. Natural coloring can be combined with these nanopigments and obtain a new product which will be environmental safe.