Pigment yellow 37 (C.I. 77199) Chemical Properties

CAS DataBase Reference

68859-25-6

Pigment yellow 37 (C.I. 77199) Usage And Synthesis

Chemical Properties

The chemical composition of pure cadmium yellow is cadmium sulfide or cadmium sulfide and zinc sulfide solid solution. Cadmium yellow color is bright and full (saturation up to 80% ~ 90%), its chromatographic range from light yellow, through the positive yellow until the red light yellow. Containing zinc sulfide cadmium yellow, the degree of its yellow with the increase in the amount of solid solution of zinc sulfide and become lighter, until light yellow. Industrial production of cadmium yellow light yellow (primrose yellow), bright yellow (lemon yellow), positive yellow (yellow), deep yellow (gold) and orange and so on. Cadmium sulfide and cadmium carbonate can also be composed of a mixture of orange, but not a solid solution. The color of cadmium yellow depends on secondary factors related to the colloidal aggregates of the pigment, and largely depends on the anionic valence of the coagulation effect. Cadmium yellow particles are spherical in form or in their aggregates. The particle size of yellow cadmium yellow is 0.04～0.4μm, the pore radius is 20～200 nm, and the specific surface is 7～8 m2/g. There are two kinds of stable forms of cadmium sulfide yellow at room temperature: one is β-CdS, which belongs to the cubic crystalline type; the other is α-CdS, which belongs to the hexagonal crystalline type. The former is called low-temperature stabilized form with heat resistance ≤500℃; the latter is called high-temperature stabilized form with melting point 1405℃ and heat resistance ≥600℃. In the range of room temperature and 500 ℃, the two crystal types of cadmium yellow can be stable coexistence. Cubic crystal of a single grain size ≤ 100mm, while the hexagonal crystal of a single crystal grains in the 100 ~ 280nm. cadmium yellow sulfide in 700 ℃ above the brown, sublimation in the nitrogen atmosphere at 980 ℃ but does not decompose, such as the presence of air is completely oxidized to CdSO4 and CdO. in the humidity and the air under the joint action of the cadmium yellow oxidation can be toxic cadmium sulfate. Cadmium yellow is insoluble in water, alkali, organic solvents and oil, slightly soluble in 5% dilute hydrochloric acid, soluble in concentrated acid, dilute nitric acid and boiling dilute sulfuric acid (1:5). Cadmium yellow is not affected by hydrogen sulfide. The relative density of cadmium yellow is 4.5~5.9, the light yellow urn is smaller than the dark yellow. β-type is more lipophilic than α-type. Cadmium yellow has good abrasive property, easy to research and reconcile with adhesive, but poor abrasive resistance. In the dry state for a long time grinding color darkening, heat treatment can make the discoloration of cadmium yellow to restore the original state. Cadmium yellow coloring power is strong, light resistance, weather resistance is excellent, no migration, no bleed color. Cadmium yellow is safe in coloring products because of its insolubility, but it is still a toxic pigment.

Definition

ChEBI: Cadmium sulfide is a cadmium molecular entity.

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