Pigments can be divided into two categories: inorganic pigments and organic pigments, based on their chemical composition. Natural pigments and synthetic pigments can be divided into their sources. Natural pigments are derived from minerals such as cinnabar, red clay, realgar, malachite green and ground calcium carbonate, wollastonite, barite powder, talc powder, mica powder, kaolin, etc. Biologically derived, such as from animals: cochineal red, natural fish scale powder, etc .; from plants: garcinia, alizarin red, indigo, etc. Synthetic pigments are artificially synthesized, such as inorganic pigments such as titanium white, zinc barium white, lead chrome yellow, iron blue, and organic pigments such as scarlet powder, even light yellow, phthalocyanine blue, quinacridone and the like. According to the functions of pigments, they are classified as anti-rust pigments, magnetic pigments, luminescent pigments, pearlescent pigments, conductive pigments, etc. Color classification is a convenient and convenient method. Such pigments can be divided into white, yellow, red, blue, green, brown, purple, black, regardless of their source or chemical composition. The famous "Color Index" (Color Index) is a method of classifying by color: such as dividing the pigment into pigment yellow (PY), pigment orange (PO), pigment red (PR), pigment purple (PV), pigment blue (PB) , Pigment Green (PG), Pigment Brown (PBr), Pigment Black (PBk), Pigment White (PW), Metal Pigment (PM) and other ten categories, pigments of the same color are arranged according to the order number, such as titanium white is PW- 6. Zinc barium white PW-5, lead chrome yellow PY-34, quinacridone PR-207, iron oxide red PR-101, phthalocyanine blue PB-15, etc. In order to find the chemical composition, there are other structural numbers, such as titanium white PW-6C.I.77891, phthalocyanine blue is PB-15C.I.74160, so that the pigment manufacturers and users can identify the listed pigments Composition and chemical structure. Therefore, it has been widely used in the international pigment import and export trade, and some domestic pigment manufacturers also use the international classification standard for this pigment. China's national standard for pigments GB / T3182-1995 also uses color classification. The color of each pigment has a mark, such as white for BA, red for HO, yellow for HU ... Combined with the code and serial number of the chemical structure, the model of the pigment is composed, such as rutile titanium white BA-01-03, medium chrome yellow HU-02-02, iron oxide red HO-01-01, zinc barium white BA-11-01, toluidine red HO-02-01, BGS phthalocyanine blue LA-61-02, etc.
Pigments usually have the following properties:
colour. Color pigment is a pigment that selectively absorbs and scatters visible light energy.
Under natural light conditions, it presents yellow, red, blue, green and other colors.
Coloring power. The ability of colored pigments to absorb incident light. It can be expressed as the relative percentage of the color strength of the standard pigment sample.
Hiding power. The ability to cover the color of the substrate surface in film-forming materials. It is usually expressed in grams of pigment contained in a paint covering an area of 1 square meter.
Lightfastness. The pigment maintains its original color performance under certain light. It is generally represented by an eight-level system, with eight being the best.
Weather resistance. The ability of pigments to maintain their original performance under certain natural or artificial climatic conditions. A five-level system is generally used, with five being the best.
Volatile. Mainly refers to moisture, the general regulation is not more than 1%.
Oil absorption. It refers to the number of grams of refined linseed oil required for 100 grams of pigment to form a uniform mass. The oil absorption is better. The oil absorption is related to the specific surface area and structure of the pigment particles.
Water soluble. The water-soluble substance contained in the pigment is expressed as a percentage of the mass of the pigment. For pigments used in paint making, the water-soluble substances are often controlled below 1%.