White Pigment Zinc Sulfide For Coloring Glass Fiber Reinforced Plastics

Zinc sulfide is white to off-white or light yellow powder. See the light darken. It is stable in dry air, and when it is placed in humid air for a long time or contains moisture, it will gradually oxidize to zinc sulfate. Zinc sulfide is soluble in dilute inorganic acid, soluble in alkali, but insoluble in water. The relative density is 3.98 (α type), (d25) 4.102 (β type). It is irritating.
 
Titanium dioxide is the most important inorganic pigment. There are three crystal types of titanium dioxide in nature: rutile (tetragonal system), anatase (tetragonal system) and brookite (rhombic crystal system). Rutile and anatase have been mass-produced industrially. Plate titanium type is difficult to produce dry, so it is not used in the pigment industry. The rutile type is a thermodynamically stable crystal type with the tightest atomic structure and therefore the highest density. The density of the anatase type is about 3.9g/cm', and the density of the rutile type is about 4.2g/cm3.

 
The rutile type is the hardest crystal form, with a Mohs hardness of 6.5-7, and anatase is softer, with a Mohs hardness of 5.5-6. The rutile type has better optical properties than anatase. In addition, rutile type is also superior to anatase type in light fastness and weather resistance. The rutile type is the best type of titanium dioxide, which is used for coloring almost all plastic types and brightening pure white or color.
 
The high hardness of rutile is a disadvantage for dry glass fiber reinforced plastics, because rutile will damage the glass fiber 2438 during the coloring process, causing serious loss of the mechanical strength of the plastic product. Therefore, the white pigment for coloring glass fiber reinforced plastics is selected from zinc sulfide 9982, which has slightly poorer optical properties and is softer.