Лако-красочные материалы — производство

With their excellent heat stability, the thermostable types can be readily incorpo­rated into polyolefins and ABS at 260-280 °C, and polyamide injection-molding materials at 280-300 °C. Even when they are applied in the manufacture of large injection-molded and extruded plastic parts, the product obtained is dimensionally stable and non-warping. Because of their excellent fastness to […]

2.5.2.1 Properties Thermostable bismuth vanadate pigments are available today with a heat stability of 260 to 280 °C. They exhibit very good fastness to light and weathering in plas­tics for outdoor use. In weathering tests on plastics pigmented with 0.5% cad­mium yellow or 1% bismuth vanadate, the bismuth vanadate pigment was super­ior both under artificial […]

Bismuth vanadate pigments are used to obtain brilliantly colored lead-free stan­dard automotive finishes, automotive repair finishes and high-grade industrial paints. They are equally suitable for pigmenting solvent-based and solvent-free paints. They are ofparticular interest as a basis for brilliant, highly opaque orange, red and green shades, for which they are combined with organic pigments. The […]

The resistance of these pigments to organic solvents is excellent. Their ionic char­acter may be a disadvantage with regard to acid/alkali resistance, but surface stabi­lization improves this significantly (see Section 2.5.1). 2.5 Applications About 95% of the total volume of bismuth vanadate pigments is used in paint manufacture and about 5% in plastics processing. This […]

The excellent dispersibility is typical for inorganic pigments of this type and is far superior to that of organic pigments. 2.4.5 Light Fastness and Weather Resistance Bismuth vanadate pigments exhibit very good light fastness in both deep and pale shades. They show excellent weather resistance in full shades, and are superior to lead chromate in […]

Bismuth vanadate pigments are characterized by brilliant, greenish-yellow to red­dish-yellow shades of high color strength, high gloss and good hiding power. When they are compared with other inorganic yellow pigments, their coloristic properties are seen to resemble those of cadmium yellow and lead chromate. Figure 2.1 shows the reflectance curves ofbismuth vanadate and other inorganic […]

The most important physical properties are: Density 5-7 g/cm3 Mean particle size 0.4-0.8 pm Specific surface area 12-4 m2/g Oil absorption 30-10 g/100 g pigment Compared with organic pigments, the density and particle size are relatively high while the specific surface area and oil absorption are quite low. This means very high pigment loading is […]

2.4.1 Chemical Properties Bismuth vanadate pigments are insoluble in water and alkalies. Only in strongly alkaline media, e. g. mixtures with cement, will they sometimes show instability and undergo a change in shade. Acid media with a pH ofless than 2 cause percep­tible solubilization, depending on how well the pigment has been stabilized. 2.4.2

Bismuth vanadate pigments are obtained by a precipitation process in which caus­tic soda or sodium hydroxide is added to a solution containing bismuth nitrate, sodium or ammonium vanadate, sodium molybdate (where specified) and nitric acid. The precipitate of oxides and hydroxides is washed until it is free of salt. To form better crystals and hence […]

Bismuth vanadate or orthovanadate, BiVO4, occurs naturally as tetragonal dreyer — ite in Hirschhorn, Germany, as monoclinic clinobisvanite in Yinnietharra, Wes­tern Australia, and as orthorhombic pucherite in Schneeberg, Germany. However, these deposits are of no practical importance to the pigment industry. Bismuth vanadate was first reported in a medical patent in 1924 and synthe­sized as […]