Zinc oxide white pigments

Zinc oxide white pigments are known as zinc white or zinc oxide depending upon the manufacturing process. 

In the manufacture of zinc white by the French process, metallic zinc is melted, evaporated and oxidized in the vapor state to zinc oxide with air. If the starting material is insufficiently pure, the zinc has to be purified by evaporation and condensation prior to the oxidation step. The size and shape of the zinc oxide crystals can be controlled by the oxidation conditions. After combustion the ZnO is precipitated from the ZnO/air mixture in settling chambers, in which classification of the zinc oxide particles takes place according to their size. 

The raw materials for the manufacture of zinc oxide by the American process are roasted ores, concentrates of zinc ores or more recently zinc hydroxide or zinc carbonate from the processing of scrap. These are reduced with coal and directly reoxidized to ZnO in the same reaction chamber. The purity of the zinc oxide is normally somewhat inferior to that from the French process. Grades of various purities can be produced by fractionation. 

Zinc is precipitated from purified zinc salt solutions as the hydroxide, basic carbonate or carbonate, which is washed, filtered and dried. The pigment is obtained by subsequent calcination. Pigments suitable for particular applications can be obtained by varying the precipitation and calcination 

Zinc oxides is mainly used in the rubber industry in which it serves as an activator in the vulcanization process. Its low hardness and high compatibility with polymers are important for its utilization in chemical materials. In its utilization in paints, its tendency to form zinc soaps, which hinder the attack of coatings by fungus and improve the aging resi.stance (UV-absorption), is important. Further application fields for zinc oxide are in copier paper, glues, pharmaceutical products, cosmetic products and dental cements. 

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White pigments, some of rather variable composition, that have been used in the past include white lead (Cl Pigment White 1), refractive index 1.9 zinc oxide (Cl Pigment White 4), r.i. 1.9 lithopone (Cl Pigment White 5), r.i. 1.84 zinc sulphide (Cl Pigment White 7), r.i. 2.3 antimony oxide (Cl Pigment White 11), r.i. 2.2. All have been eclipsed by titanium dioxide (Cl Pigment White 6). 

Several less common coating pigments are used in specialty applications. These include blanc fixe, satin white, zinc oxide, plastic pigment, aluminum trihydrate and the newly introduced structured kaolin pigments. 

White Pigments. Opaque white pigments commonly used in inks, in order of decreasing opacity, ate titanium dioxide and zinc oxide. TiO is by fat the most popular white pigment. Mixtures of whites ate often made with the various colored pigments to add opacity or to make pastel colors. 

Zinc oxide [1314-13-2] (mol wt 81.37 Cl Pigment White 4, Cl No. 77947) is a white or yellowish white amorphous, odorless powder with pH 6.95—7.37. It is practically iasoluble in water but soluble in dilute acetic acid, mineral acids, ammonia, ammonium carbonate, and alkaU hydroxides. 

Pigments or dyes may be added at this stage and where clear water-white sheet is required a small amount of a soluble violet dye is added to offset the faintly yellow colour of the natural mix. Stabilisers such as zinc oxide, zinc acetate or urea may be added to prevent the composition from developing acidity. 

Zinc oxide is the most important zinc compound. The principal industrial use of zinc oxide is as a catalyst to shorten the time of vulcanization in the production of mbber. The compound also is used as a white pigment in paints, cosmetics, and photocopy paper, hi everyday life, ZnO is also a common sunscreen. 

Bluish, shimmering, brittle, relatively reactive metal. Is guite guickly covered with a protective oxide layer, which is why iron is treated with zinc With copper, forms the popular alloy brass, which was already known in antiquity. Used in batteries and as a stabilizer in plastics. Zinc oxide is used as a white pigment Zinc ions are essential to all life forms, e.g., as a component of alcohol dehydrogenase and many other enzymes. Hence human beings (70 kg) carry about 2.3 g (half as much as iron). 

A co-precipitated mixture of approximately 28% zinc sulphide, 71% barium sulphate and 1% zinc oxide. It is used as an extending filler and white pigment. 

American Also known as the Wetherill process, and the Direct process. A process for making zinc oxide, in the form of a white pigment, from a zinc oxide ore. The ore is usually franklinite, which is predominately ZnFe204. The ore is mixed with coal and heated in a furnace to approximately 1,000°C, forming zinc vapor in a reducing atmosphere. The vapors pass to a second chamber in which they are oxidized with air, forming zinc oxide and carbon dioxide. See also French. 

Titanium white pigments, commercial production of, 19 388 Titanium white rutile pigment, 19 391 Titanium zinc oxide, 5 603 Titanium-zirconium-molybdenum (TZM) alloy, 17 14-15 Titanocene, 25 118 Titanocene catalysts, 16 19 Titanocene dichloride, 25 105 Titanocene synthons, 25 116 Titanocycles, 25 116... 

Chinese white chem A term used in the paint industry for zinc oxide and kaolin used as a white pigment. Also known as zinc white. chTn nez wTt chinic acid See quinic acid. kin ik as ad chinoldine See quinoidine. ki noT.den chinone See quinone. kin on ... 

Zinc oxide is an example of zinc(Il) combining with a —2 anion. (Zn + O —> ZnO). Zinc oxide is also added to paints as a pigment and mold inhibitor and is known as zinc white when it is used as an oil paint by artists. It is used for cosmetics (ointment to protect nose and bps from ultraviolet sunlight), as a seed treatment, and as a dietary supplement. 

Zinc oxide occurs in nature as mineral zincite. It is the most important zinc compound and has numerous industrial applications. Zinc oxide is the pigment in white paints. It is used to make enamels, white printing inks, white glue, opaque glasses, rubber products and floor tiles. It is used in cosmetics, soaps, pharmaceuticals, dental cements, storage batteries, electrical equipment, and piezoelectric devices. Other applications are as a flame retardant, as a UV absorber in plastics, and a reagent in analytical chemistry. A major application of zinc oxide is in the preparation of most zinc salts. In medicine, the compound is used as an antiseptic, an astringent and a topical protectant. 

Zinc oxide (ZnO) is widely used as an active filler in rubber and as a weatherability improver in polyolefins and polyesters. Titanium dioxide (TiOj) is widely used as a white pigment and as a weatherability improver in many polymers. Ground barites (BaS04) yield x-ray-opaque plastics with controlled densities. The addition of finely divided calcined alumina or silicon carbide produces abrasive composites. Zirconia, zirconium silicate, and iron oxide, which have specific gravities greater than 4.5, are used to produce plastics with controlled high densities. 

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