DE2150663C3 - Process for the production of inorganic pigments - Google Patents

Description

The invention relates to a process for the production of inorganic pigments according to the preamble of Claim.

It is already known to stir or add liquids by means of a changing magnetic field mix. Permanent magnets with a size of 0.1 μ to 1 cm are incorporated into the liquid. These elements can have the shape of rods or needles and provide protection against corrosion be provided with a coating made of plastic, rubber or the like. The magnetic field is a single-phase alternating field used, with which a relatively low induction is achieved (US-PS 32 19 318).

It is also known by means of a magnetic penetrating the wall of a circular container Rotating field the liquid in the container, which is electrically conductive, by induction to set eddy currents in a rotational movement around the container axis. Because this rotational movement would decrease towards the axis, an annular container is used. The through the Magnetic field-induced movement of the liquid is used for treatment, for example for cleaning, Refinement, but especially for mixing. This also means that liquids are mixed with low or no electrical conductivity is possible, are freely movable in the liquid Body with high electrical conductivity, for example metal balls, introduced into which below Eddy currents are induced under the influence of the rotating magnetic field, causing the balls to move in Bring the direction of the rotating field. The movement of these balls is transferred to the surrounding area Liquid, which also sets the liquid in motion. The metal balls can protected against corrosion by a coating (DT-PS 3 16 499).

These known measures are only used to stir or mix liquids.

The prior art also includes a method in which titanium white is produced the titanium sulphate solution intended for hydrolysis is passed through a magnetic field, the magnetic field with a frequency of 5 Hz (CS-PS 1 36 245).

It is also known to achieve a higher degree of dispersion of dyes that du suspension through a series of successive magnetic fields with alternating directions

(USSR copyright certificate 1 44 928).

These known processes have the disadvantage that the pigments have already ripened and that only then is an improved dispersion brought about by influencing it by means of a magnetic field is, so that the entire process takes a relatively long time and the properties of the pigments obtained do not are always satisfactory.

The object on which the invention is based is now to use suitable measures to prepare the synthesis and to realize the ripening process of the inorganic pigments in very short times, the obtained Pigments have surprisingly good properties with regard to their color intensity.

is This task is carried out by the Claim listed measures resolved.

The measures used according to the invention have the advantage that the course of the synthesis and The ripening process of the pigments goes on very quickly, which is due to crystal lattice defects of the reaction components as well as the resulting products and the numerous crystallization centers that arise is. The pigments obtained using the measures according to the invention have a coloring effect which is superior to pigments produced by known processes, but which are not was predictable. Another effect that promotes the precipitation reaction and the ripening of the pigments is seen to be within the stated design limits of the rod-shaped particles an initially increasing and then decreasing formation of hydroxyl ions in the water is brought about.

example 1

Process for the production of
inorganic pigment - yellow lead-chrome paint

The rotating magnetic field is generated, its induction value 0.15 Tesla and the speed of rotation 3000 revolutions / min. This field is z. B. generated with the help of a generator. Afterwards will in this field the reaction container with a capacity of 1.5 l is housed, in which ferromagnetic chromium plated or polyethylene-coated particles are introduced in an amount of 150 g. In the reaction vessel 200 ml of lead salt solution are added at the same time: basic lead nitrite nitrate or lead acetate in one concentration of 100 g / l, calculated on the metal lead, and the solution of the mixture of precipitants in one A volume of 200-400 ml is poured in in a stoichiometric proportion to the lead salt. The mixture of Precipitant contains the chromate ion and the sulfate ion, the ratio of which depends on the desired ratio in the finished chrome color is chosen.

The dimensions of the cylindrical ferromagnetic particles are: diameter 1.8 mm, length 13.6 mm; pH of the reaction mass 2-6, the temperature

wi 20-50 ⁰ C. Atmospheric pressure prevails.

The residence time of the reaction mass in the electromagnetic field is 0.5-30 seconds. This duration was chosen for the reason to ensure the crystal formation of the pigment with increased color power.

i "i afford.

The pigment particles are down to a hundredth μιη dispersed continuously, with additional Form crystallization centers.

A lead-chrome paint is obtained in high yield which is better for coloring, i.e. with the Using a smaller amount of pigment you can get a coloring of the same color.

The pigment suspension is then subjected to filtration, the pigment paste is washed out and brought to the finished pigment form The pigment can be in the form of dry chrome paint, in this Trap, the washed out paste is dried and ground, or in the form of non-aqueous paste obtained; in this case the dehumidifying of the washed-out paste is carried out according to known methods carried out

Example 2

Process for the production of
inorganic pigment - lead molybdate chrome paint

The rotating magnetic field is generated which is analogous to that described in Example 1

In this box, the reaction vessel is 1.51 Contents housed in which ferromagnetic chromed or polyethylene-covered particles in an amount of 150 g and 200 ml of 0.1 η solution of lead nitrate are introduced. In the reaction vessel 200 ml of solution of the mixture of precipitants are poured, which the chromate ion, the sulfate ion and contains the molybdate ion, the ratio of which depends on the desired ratio in the finished chrome color is chosen. One uses lead salt solution in a slightly higher than the stoichiometric one Amount in relation to the mixture of precipitants, so that in the reaction mass after Drain the solution of the mixture of precipitants if traces of lead ions are present.

The dimensions of the cylindrical ferromagnetic particles are: diameter 1.6 mm, length 11.2 mm, pH of the reaction mass 2-5, temperature 20-25 ° C, atmospheric pressure.

The residence time of the reaction mass in the electromagnetic field is from 10 to 30 minutes. These Duration was chosen to allow the pigment to crystallize and give it more color and to ensure the desired color.

The chrome color suspension obtained is with a solution of aluminum sulfate or sodium silicate or stabilized with their mixture in an amount of 0.5-3% of the weight of the chrome paint obtained. then the pH of the suspension is increased to 6.3-7.0 with the sodium carbonate solution, filtered, dried, and grind in a known manner.

Example 3

Method of manufacture
of inorganic pigment white lead

The rotating magnetic field is generated, which is analogous to that described in Example 1.

In this field the reaction container of 1.5 l capacity is placed, in which ferromagnetic chromed or polyethylene-covered particles in the amount of 150 g, 400 ml of water, black lead and Acetic acid are introduced. Stoehiometric amounts of molten metal and acetic acid are used to produce the monobasic lead acetate solution in a concentration of 35-50 g / l. Afterwards, the Reaction container let the carbonic acid through.

Dimensions and shape of the ferromagnetic particles are the same as in Example 2. The temperature is 20- 60 ⁰ C under atmospheric pressure. The residence time of the reaction mass in the electromagnetic field is 1-5 minutes. The pH of the suspension obtained must be at least 6.4. Lowering the pH leads to a deterioration in the color of white lead.
By dispersing the platelet particles

ίο they are very quickly dissolved in weak acetic acid The resulting basic lead acetate solution reacts with the carbon dioxide that has passed through, which is below these Conditions up to tiny gas bubbles break up This causes the contact of the reacting substances significantly larger. The particles of pigment-white lead are obtained. It is possible the crowd the acetic acid below the stoichiometric, namely to 1-3 g / l. In this case the after The acetic acid released by the precipitation of white lead, in turn, participates in the dissolution of the black lead.

Such a decrease in the amount of acetic acid gives the possibility of washing out the pigment paste abbreviate or exclude.

The pigment obtained has a pure white color, which indicates the optimal shape and extent of Pigment particles is due. The pigment suspension is then subjected to filtration, which Pigment paste is washed out and made in the form of aqueous paste, or the washed out one Paste is dehumidified according to known methods and in the form of non-aqueous, ζ. B. oil paste produced.

Example 4

Method of manufacture
of inorganic pigment-yellow iron oxide

The rotating magnetic field is generated, which is analogous to that described in Example 1.

In this field the reaction vessel with a capacity of 1.5 l is placed, in which ferromagnetic chromium-plated or polyethylene-covered particles in an amount of 150 g, 60-370 ml of solution of ferrous sulfate in a concentration of 160 g / l, are obtained on FeSCu 7 H2O are introduced. Afterwards, the solution of an alkali agent, e.g. B. poured ammonia in the amount that is necessary for the precipitation of ions of divalent iron by 50%. The precipitation temperature is 15-25 ⁰ C. After starting at the same temperature the precipitate with oxygen or air, or with the solution of Bertholle Chen salt to oxidize. The germ suspension is obtained. The end of oxidation is checked after the color of the germ suspension has changed to light yellow.

The iron (II) sulfate in the form of solution or crystals is also added to the germ suspension obtained or their mixture introduced in such an amount that the amount of the germ suspension, converted to FeOOH, 6-20% of the desired amount of pigment. The pH of the suspension is determined by the introduction of the Solution of an alkali agent, e.g. B. Maintained ammonia in the range of 3-7 without the oxidation of the precipitated precipitation with oxygen or air

tv> cancel. The temperature at this stage of the Precipitation and oxidation are maintained in the 70-85 ° C range. The length of stay of the Reaction mass in the electromagnetic field is 1

up to 15 hours. The process of making the The pigment suspension is terminated when the pigment concentration in the reaction mass is 100-200 g / l and the desired pigment color can be achieved.

The dimensions and shape of the ferromagnetic particles are the same as in Example 1.

The precipitated particles are down to a hundredth of a μητ, the oxygen or air bubbles up to the tiniest vesicles are continuously dispersed, which accelerates the oxidation process of the original precipitated precipitate, for the formation of additional, crystallization centers and for shaping of the desired yellow iron oxide crystal of improved color strength and color characteristics beitritgL

The pigment suspension is then subjected to filtration, the pigment paste is washed out, dried and ground by known methods.

According to a variant of this example, yellow egg oxide from metallic iron in the medium of a Iron salt, e.g. B. iron (II) sulfate are produced.

Example 5

Method of manufacture
of inorganic pigment copper oxide

The rotating magnetic field is generated, which is analogous to that described in Example 1.

The reaction container with a capacity of 1.51 is accommodated in this field, in which ferromagnetic chromium-plated or polyethylene-covered particles in an amount of 150 g and 200 ml of copper (II) sulfate solution in a concentration of 200 g / l are introduced. The sodium sulphide solution is then poured into the reaction vessel in a concentration of 100-150 g / l in a stoichiometric ratio to the copper salt. The pH of the reaction mass is maintained in the range of 3 to 5 by the addition of the sodium carbonate solution. The dimensions and shape of the ferromagnetic particles are the same as in Example 1. The temperature is 20-50 ° C under atmospheric pressure. The residence time of the reaction mass in the electromagnetic field is 0.5-2.0 hours. This duration is chosen to ensure the full reduction of the divalent copper to the monovalent copper and the formation of a pigment of increased color strength, improved color characteristics and increased base material content.
The pigment suspension is then subjected to filtration. The pigment paste is produced either in the form of an aqueous paste or with the aid of solvents, e.g. B. dehumidified by acetone by known methods.

Example 6

Method of manufacture
of inorganic pigment titanium dioxide

The titanyl sulfate solution with the content of TiO ₂ against 200 g / L of Ti ₂ O ₃ of 3-5 g / ^{l and the Fe + 2} : TiO ₂ ratio of 0.25: 1 and H _{2 is obtained from the titanium concentrates according to known methods} SO ₄ : TiO ₂ ratio of 2: 1 produced The nucleus suspension is obtained by the usual methods.

The 1.5 l reaction container is placed in the field. It contains ferromagnetic particles in an amount of 75 g and 300 ml of titanyl sulfate solution. The dimensions of the ferromagnetic particles are: diameter 0.5-0.8 mm, length 1.5-2.0 mm. The particles are coated with a polymer, e.g. B. with polyethylene or polyvinyl chloride protected.

One heats the contents of the reaction container at 70 ⁰ C. and the bacterial suspension in an amount of 0.5-1%, calculated on TiO _2, a. The contents of the reaction vessel are then heated to the boil, boiled for 0.5 hour under atmospheric pressure, diluted quickly with 1/3 of the volume of ^{water heated to 100 °} C. and boiled again for 0.5 hour. The residence time of the reaction mass in the electromagnetic field is 1.0-1.5 hours. A yield of at least 97% of pigment particles of increased tinting power with a pure white color is obtained.
The suspension of metatitanic acid is cooled, filtered, washed out with the purified water to remove ions of divalent iron, processed with salts, annealed, ground and either used as a finished product or subjected to additional processing, dried, ground.

Claims (1)

Claim: Process for the production of inorganic pigments, wherein the pigment from aqueous salt solutions is precipitated with the simultaneous action of a magnetic field, characterized in that the precipitation in solutions of lead, iron, copper or titanium salts in the presence of cylindrical ones ferromagnetic particles with a length to diameter ratio between 1.1 and 30 under the action of a rotating electromagnetic field with a magnetic induction of at least 0.1 Tesla is carried out.