White crystalline powder.It is a mixture of zinc sulfide and barium sulfate. The more zinc sulfide, the stronger the hiding power and the higher the quality.Density: 4.136~4.34 g/cm3, insoluble in water.It is easy to decompose in case of acid to produce hydrogen sulfide gas, but it does not work in case of hydrogen sulfide and alkali solution.It will become light gray after being exposed to ultraviolet ray in sunlight for 6-7h, and it will return to its original color after being put in dark place.It is easy to oxidize in the air and agglomerate and deteriorate after being damped.
White powder, a mixture of zinc sulfide and barium sulfate.
Its whiteness and hiding power are stronger than zinc oxide, and its refractive index and opacity are higher than zinc oxide and lead oxide, but lower than titanium dioxide.[1]
Lithopone pigment ratioZinc sulfideIt is widely used.Similar to zinc sulfide in structure, containingbarium sulfateComposition and durability are slightly poor.Poor pulverization resistance.The price is cheap, so it can be partially replacedtitaniause.
Under ultraviolet light, ZnS fades to gray.To avoid this problem, we can prepareLithoponeWhen adding nickel powder and iron powdercalcinationCobalt and copper.
physical characteristics
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relative density
Among the commonly used white pigments, lithopone has the smallest relative density. Among white pigments of the same quality, titanium dioxide has the largest surface area and the highest pigment volume.
granularity
Lithopone particle size distribution is a comprehensive index, which seriously affects the performance of lithopone pigment and product application performance. Therefore, the discussion of hiding power and dispersibility can be directly analyzed from the particle size distribution.
synthetic method
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The natural barite containing more than 95% barium sulfate is mixed with anthracite at 3:1 (mass), crushed to a diameter of less than 2cm and enters the reduction furnace. The front section of the furnace temperature is controlled at 1000~1200 ℃, and the rear section is controlled at 500~600 ℃. The reduction furnace rotates at the speed of 80s per revolution, and the reaction conversion rate is 80%~90%. The prepared barium sulfide enters the leacher, and the control temperature is above 65 ℃,The content of barium sulfide obtained is 701%, and then enters the clarifier. After clarification, zinc sulfate is added for reaction. The content of zinc sulfate is controlled to be more than 28%, pH=8~9, and the mixture of barium sulfate and zinc sulfide with a density of 1.296~1.357 g/cm3 is obtained.The reaction liquid is filtered by plate and frame pressure to obtain filter cake shapeLithopone, the water content is not more than 45%, and it is baked in the drying roasting furnace to changeLithoponeCrystal form, and then acid pickling with sulfuric acid at 80 ℃.Finally, it is made by water washing, reinforcing color agent, filter pressing, drying and grinding.
2. The calcined product obtained by the preparation of ordinary lithopone is beaten to make slurry, and sodium silicate, aluminum sulfate or sodium aluminate andsurface active agent After surface treatment, it can be filtered, washed, dried and crushed.[3]
purpose
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Used for coloring paint, ink, rubber, etc.
Inorganic white pigment, widely used in polyolefinVinyl resin、ABS resin、polystyrene、polycarbonate, nylon, polyoxymethylene and other plastics, as well as white pigments for paints and inks.In polyurethane andAmino resinIt is not suitable for fluoroplastics.Also used forRubber productsColoring of paper, linoleum, oilcloth, leather, watercolor pigment, paper, enamel, etc.It is used as adhesive in the production of electric balls.[4]
