DE1936312B1 - Process for the production of finely divided raw pigment powders - Google Patents

Description

The invention relates to a method for the production of finely divided Crude pigment powders which are surprising when treated with organic contact substances smoothly and quickly give dyes with excellent pigment properties.

Many pigments, especially the lightfast and solventfast non-azo pigments, after washing and drying, d. H. after finishing the final stages of theirs Manufacturing process, obtained in a form in which it is still in the art are not optimally usable because z. B. such important pigment properties as dispersibility, Color strength, tone purity, transparency, solvent fastness and color nuances all or are partially missing or poorly developed. The causes for this Defects vary according to the medium from which the pigments are obtained. the end aqueous phase is obtained, for. hard, difficult to disperse agglomerates, made of organic Media mostly coarse crystalline raw pigments.

In such cases, the technically not yet usable »crude pigments« are subjected to a reshaping (modifying) post-treatment, the task of which it is to remedy the defects mentioned.

One of these aftertreatment methods is that the raw pigments brings into intimate contact with certain, mostly liquid organic substances. This can be done either by grinding and stirring or by heating at normal temperature or increased pressure.

If you look at these aftermaths of organic "raw pigments" r With organic liquids emanating from dried pigments, it is crucial Meaning that they either prior to bringing them into contact with the organic contact substances or during the treatment with these by grinding with and without aids be brought into as high a fine distribution as possible, because this results in the contact transformation with the organic means either: simplified or overpowered replacement possible will.

Suitable technical crushing devices for these processes are z. B. Ball mills and rod mills. With such mills one obtains by grinding with or without grinding aids (e.g. organic salts) sufficient comminution, but the processes have a number of serious disadvantages. So -is-e.g. The capacity of this apparatus is unsatisfactory. This is due to, that, on the one hand, the grinding times are very long and, on the other hand, the zero content of these Aggregates is very small. The former are generally between 6 and 22 hours, uddas '; for the filling with the': pigment available mill volume, This is already very small due to the high space requirements of the 'spheres or rods is't, is reduced again considerably when using grinding aids. So take z. B. the grinding parts of such mills, so balls or rods, mostly half the volume of such mills, and their weight exceeds that of the substances to be ground often by more than 50 times.

For grindings that are carried out without grinding aids (such as those in the German Auslegeschrift 1225598 have been described) and therefore in relation are more favorable to the use of space, a major deficiency occurs as a result, that as a result of the high Friction between the mill chuck and grinding media is considerable Abrasion takes place, through which on the one hand the pigment is degraded in its quality and on the other hand the mill is subjected to severe wear. In cases where so-called grinding aids are also used, theirs lies Amount generally between 4 and 20 times the amount of the pigment, whereby the Useful content is again considerably reduced.

The long grinding times, the small usable capacity of the equipment and the abrasion in these are in the previously used comminution methods The reason for the relatively poor performance of this process. At their elimination consisted of both technical and economic reasons a significant interest.

It has now been found that, in the case of pigments, comminution of of the highest degree of fineness, which is suitable for modification by treatment with organic contact substances are ideal if you are dry Mixtures of pigments and water-soluble grinding aids in one high-speed Agitator stirred. The fine distributions required for contact modification are generally achieved in 1 to 4 hours.

As grinding aids, - water-soluble salts of organic or inorganic acids are used: 5.

For contact modification * avir'd after dry stirring with added an organic solvent and briefly to wet the pigment powder stirred further. It is: extremely advantageous, the pigment dispersion obtained from this bring to the boil before stirring.

Liquid, aliphatic and aromatic solvents can be used as organic solvents and heterocyclic hydrocarbons and their various derivatives are used will. s -After the removal of the solvent by DestiXlation, steam distillation or washing can be done, the grinding aid is obtained by filtration and washing removed with water.

The pigment powders obtained after drying and grinding have in organic binders (paints, varnishes) and in plastics (PVC), in contrast to the untreated starting dyes, excellent pigment properties.

With this method, the above-mentioned disadvantages of the ball or Rod mill grinding bypassed, and the resulting products are of such a high degree of fine distribution, that for the subsequent contact conversion generally not more than 5 to 10 minutes are required.

(Ratio of pigment to grinding aid in these mixtures - 1: 3).

Example 1 4 kg of raw dioxazine violet (CI pigment violet 23) become dry for 3 hours with 8 kg of table salt (chemically pure) with a high-speed stirrer (2000 rpm) stirred.

For the contact modification, 16 kg of 2-nitropropane are added and stirring continued for a short time, the mixture becoming noticeably more viscous.

Then the 2-nitropropane is distilled off with steam, the The distillation residue was stirred 3 times with 60 l of water each time and washed by decanting. To After filtering, the washing on the filter is repeated 3 times with 40 l of water each time and the pigment paste is then dried at 800.degree.

The violet pigment powder obtained has compared to the crude pigment an excellent development of color strength and final strength.

Example 2 3 kg of crude dibromoanthanthrone (CI-Vat orange 3) become with 9 kg of table salt (chemically pure) with a fast mixer (2000 rpm) for 3 hours stirred dry.

For contact modification, 12.3 kg of 2-nitropropane are added and stirring continued for a short time, the mixture becoming noticeably more viscous.

Then the 2-nitropropane is distilled off with steam, the distillation residue 3 times with 601 each Stir water and wash by decanting.

After filtering, wash on the filter 3 times with 40 1 water repeated and the pigment paste then dried at 800 C.

The violet pigment powder obtained has compared to the crude pigment excellent color strength development and final color strength.

Claims (1)

Claim: Process for the production of finely divided raw pigment powders by Grinding of dry mixtures of pigments and water-soluble grinding aids for the purpose of a later modification with organic contact substances, thereby characterized in that the grinding is carried out with a high-speed agitator.