Лако-красочные материалы — производство

Selenium is positioned between sulfur and tellurium in Group VIb (chalcogens) of the periodic table, and exhibits properties similar to both these elements. It is more metallic than sulfur but less so than tellurium. Like other members of the group it exhibits allotropy and exists in red and gray forms. It exhibits several valency states, […]

3.3.1 Cadmium Cadmium is positioned in Group Ilb of the periodic table, which is sometimes known as the “zinc group”. It is positioned between zinc and mercury, and thus has some similar properties to these elements. Cadmium metal is silvery white and reasonably soft. Although it does form some complexes, its pigment chemistry is entirely […]

An even rarer element, selenium is present at approximately 50 parts per billion of the earth’s crust. It is much rarer than its neighbor in the periodic table, sulfur. The ratio of selenium to sulfur has been calculated to be about 1:6000! Like cadmium, selenium is mainly derived from the purification of other mineral ores, […]

3.2.1 Cadmium A naturally occurring but rare element, cadmium occurs as approximately 150 parts per billion of the earth’s crust. Although cadmium sulfide does occur natu­rally as the mineral Greenockite (named after the Scottish coastal town Greenock), no commercially viable deposits of cadmium exist. It is derived primarily as a waste product from the refining […]

Cadmium compounds were first used as colorants shortly after the yellow com­pound cadmium sulfide was discovered by the German metallurgist Friedrich Stromeyer. The element cadmium was discovered by several chemists in 1817. Stromeyer was however the first to report it and is credited with its discovery. He recommended that the brightly colored yellow sulfide be […]

Paul Dunning 3.1 Introduction Of all the inorganic pigments, cadmiums have the broadest range consisting of brilliant yellow and red colors. The yellows span from pale primrose to deep golden yellow. Reds vary from light orange, progressing to deep orange, light red, through crimson and maroon (see Figure 3.1). Cadmium yellows are composed of cadmium […]

Bismuth vanadate pigments exhibit low solubility in water. They can therefore be removed from wastewater largely by mechanical means, for example in waste­water treatment plants. An appreciable increase in water solubility occurs only at pH levels of less than 2. They exhibit practically no toxicity to fish, daphnia or bacteria, as evidenced by the following […]

Animal trials with respirable dust gave some indication of inhalational toxicity, the effects of which were reversible at low concentrations. To alleviate the asso­ciated risk, some manufactures supply bismuth vanadate pigments in a free-flow­ing, low-dusting form, making them inaccessible to the lungs. The safety of these pigments is reinforced by their high density, which causes […]

No adverse toxicological effects were observed in animal tests involving oral and inhalational intake of the pigments. LD50 rat, oral > 5000 mg/kg LC50 rat, inhalational > 5.15 mg/L/4 hours Skin irritation Non-irritant (tested on rabbit) Mucous-membrane irritation Non-irritant (tested on rabbit’s eye) Mutagenicity (Ames test) Negative (tested on five strains of bacteria with and […]

The good insolubility of bismuth vanadate pigments is reflected in their fastness to migration. They can be used in typical commercial concentrations for coloring plastics for food packaging and other materials and articles in accordance with the purity requirements of the following countries for colorants in food packaging: Germany (RECOMMENDATION IX of the Federal Institute […]