Лако-красочные материалы — производство

Bismuth oxychloride is produced by the hydrolysis of very acidic (pH <1.0) bismuth solutions in the presence of chloride. Bi(NO3)3 + HCl + H2O ^BiOCl + 3 HNO3 The crystal quality can be varied by careful adjustment of bismuth concentration, temperature, pH, pressure, reactor geometry, and by addition of surfactants. The usually tetragonal bipyramidal structure […]

The first commercially successful synthetic pearl luster pigments were hexagonal lead salt crystals, especially basic lead carbonate Pb(OH)2 • 2 PbCO3. Basic lead car­bonate is precipitated from aqueous lead acetate with carbon dioxide under carefully controlled reaction conditions. 3 Pb(CH3COO)2 + 2 CO2 + 4 H2O ^Pb(OH)2 -2 PbCO3 + 6 CH3COOH The resulting platelets […]

Natural pearl essence is isolated as a silky lustrous suspension from fish scales. The organic pigment particles in the suspension are platelet-shaped with a very high aspect ratio (0.05 pm x 1-10 pm x 20-50 pm), and consist of 75-97% guanine and 3-25% hypoxanthine (natural fish silver) [5.122, 5.123, 5.128, 5.130]. Today there is no […]

The physical background of optical interference effects has been the subject of many publications [5.122-5.125, 5.127-5.130]. The optical principles of pearl luster (inter­ference) pigments are shown in Figure 5.16 for a simplified case of nearly normal incidence without multiple reflection and absorption. At the interface Pi between two materials with refractive indices n1 and n2, […]

5.3.1.1 Introduction Special effect pigments, which can be natural or synthetic, show outstanding qualities of luster, brilliance and iridescent color effects based upon optically thin layers [5.122­5.125]. This visual impression develops by reflection and scattering of light on thin multiple layers. In nature this is not limited to pearls and mussel shells alone; there are […]

The class of effect pigments (luster pigments) comprises the two main groups of spe­cial effect pigments including pearl luster pigments (pearlescent pigments, nacreous pigments, interference pigments) and metal effect pigments. All these pigments consist of small thin platelets that show strong lustrous effects when oriented in par­allel alignment in application systems (e. g. in paints, […]

In the EC lead-, chromate — and zinc phosphate-containing anticorrosive pigments must be appropriately labeled. Such substances must carry the following symbols and indications of danger [5.112]: Lead-containing anticorrosives (Red Lead, lead silicochromate) T, Toxic (skull and cross bone) N, Dangerous for the environment (dead fish/tree) R-phrases: R61-20/22-33-50/53-62, S-phrases S53-45-60-61 Zinc chromate, zinc potassium chromate, […]

Precautions have to be taken and workplace concentration limits have to be observed when handling the various anticorrosive pigments. General regulations exist for all lead-containing materials like Red Lead or lead silicochromate. Concentration limits are as follows: <0.1 mg m 3 <70 pg dL-1 < 30 pg dL-1 <15 mg L-1 <6 mg L 1 […]

The changes in the toxicological classification of lead — and chromate-based anticor­rosive pigments have resulted in reappraisal ofthe formulation ofanticorrosive coat­ings. 5.2.16.1

Protective coatings are specified in numerous national and international standards. For example, the extensive control description, ISO 12944 — Paints and varnishes — Corrosion protection of steel structures by protective paint systems — deals with the protection of steel by paint systems and covers in eight parts more or less all features, which are important […]