Pigment (lat pigmentum- paint) - a component of the filled composite materials, materials giving opacity, color, and other anti-corrosion properties. Often used as a synonym for inorganic dye. Distinguish natural mineral pigments (inorganic components of paints) and biological pigments (biohromy- natural dyes composed of living organisms).
In the technology of paints pigments called superfine inorganic or organic, insoluble in the dispersion medium substances which may form with the film former protective, decorative or decorative and protective coatings.
The most important representatives
White: titanium dioxide, zinc oxide, lithopone, white lead. Last practically superseded titanium dioxide pigments which are titanium dioxide mixture with barite or zinc oxide and then titanium dioxide. Zinc oxide has a yellowish tint and inferior titanium cost.
Black: carbon black, carbon black, iron oxide black pigments
Colored inorganic pigments:
yellow iron oxide, ocher
red iron oxide, red lead (iron and lead)
ultramarine, steel blue, Prussian blue
Organic pigments are: azo pigments, phthalocyanine pigments, polycyclic pigments
Pigments are solid components of the composite paint materials - paints, enamels, primers, putties and powder formulations.
The incorporation of pigments in paints is the main method of controlling the properties of decorative coatings - color and opacity (opacity).
Pigment gives coverage pigmented material is if its refractive index above the refractive index of the film former. The greater the difference in refractive index of the pigment and film former, the more the coverage of such pigmented material. In addition, the important form of the pigment particles, such as leaf shape of the particles of the pigment gives more coverage than a needle or spherical.
The incorporation of pigments and fillers can adjust and other important properties of composite materials - deformation-strength, insulation, anti-corrosion, adhesion strength, as well as to obtain coatings with special properties - conductive, electrically insulating, heat-resistant, fire-retardant, etc. Along with the pigments for filling polymer coatings employed excipients
The most important properties
Physical properties of the crystal structure, refractive index, color, density, hardness, shape and size of the particles (dispersion), the specific surface area, bulk density, solubility.
Chemical properties: pH of the aqueous extract, resistance to water and chemical reagents, reactivity, acid-base properties of the surface.
Physicochemical properties: wettability (lipophilic or hydrophilic), the density and strength of the packing of the particles in the aggregates, the adsorption capacity of the surface, the photochemical activity, lightfastness, phototropic, the ability to change the potential of the electrode surface (passivation effect).
Technological properties: coverage, coloring power (intensity) Oil absorption, dispersibility, the critical volume fraction, structuring ability, weather resistance, compatibility with other system components.