초록 ▼

In conventional dry milling of C.I. Pigment Violet 23, the environment is heavily polluted by the necessarily formed dusts, the resulting noise and vigorous vibration during the milling process. According to the invention, it has now been found that these shortcomings can be avoided by carrying out

In conventional dry milling of C.I. Pigment Violet 23, the environment is heavily polluted by the necessarily formed dusts, the resulting noise and vigorous vibration during the milling process. According to the invention, it has now been found that these shortcomings can be avoided by carrying out the comminution of the base pigment by aqueous-alcoholic milling in the presence of beads and selected pigment dispersants derived from dioxazine compounds containing basic groups, followed by a solvent finish. Such a combination of the two abovementioned treatment operations even makes it possible to increase the capacity without the need for any other expensive investments for constructional modifications of the equipment. The pigment preparations produced in this manner simultaneously result in an improvement of the colorant in the paint and especially in nitrocellulose gravure printing upon practical application, in particular in an improvement of the gloss and a reduction in abrasiveness, compared with commercial grades known in this area.

대표청구항 ▼

A process for the preparation of pigment preparations based on C.I. Pigment Violet 23 (No. 51 319) of the formula I [Figure] (I) which process comprises the process steps of a) wet milling the coarsely crystalline pigments of the above dioxazine compound in the presence of pigment dispersants of the

A process for the preparation of pigment preparations based on C.I. Pigment Violet 23 (No. 51 319) of the formula I [Figure] (I) which process comprises the process steps of a) wet milling the coarsely crystalline pigments of the above dioxazine compound in the presence of pigment dispersants of the formula II Q[-Y-X]m (II) in which Q is an m-valent radical of the base structure in accordance with formula I, Y is a bridge-forming grouping selected from the series consisting of －CH2－, －CHR1－, －CR1R2－, phenylene, －CO－, －SO2－, or －NR3－, or a multiple sequence of alkylene or a combination of such bridging members of different types, which may be repeated, in which R1 and R2 are identical or different C1-C4-alkyl and R3 is hydrogen or C1-C4-alkyl, X is the radical of an aliphatic or aromatic, five- or six-membered heterocyclic system bound to bridging member Y via a carbon atom and each containing 1 to 3 identical or different hetero atoms belonging to the ring and being selected from the series consisting of nitrogen, oxygen and sulfur, which can additionally contain a benzo-fused ring and be substituted by C1-C4-alkyl, C2-C4-alkenyl, C1-C3-hydroxyalkyl or phenyl, or is a phthalimido radical bound to bridging member Y via the imide nitrogen, which may be substituted on the benzenoid ring by chlorine, bromine, nitro, carboxyl, N-(C1-C5-alkyl)carbamyol, N-phenylcarbamoyl or benzoylamino, or is a radical having the structure [Figure] in which R4 and R5 each individually and independently of one another are each hydrogen, substituted or unsubstituted C1-C20-alkyl or C2-C20-alkenyl, C5-C6-cycloalkyl, substituted or unsubstituted phenyl, benzyl or naphthyl, or in which R4 and R5 jointly or together with the adjacent N atom form an aliphatic or aromatic, five- or six-membered heterocyclic system each having 1 to 3 identical or different hetero atoms belonging to the ring and being selected from the series consisting of nitrogen, oxygen or sulfur, and m is a numerical value of between 0.1 and 4, in which in the case of the multiple presence (m>1) of components X and Y in the dispersants of the formula II the meaning of the symbols just mentioned does not have to be identical, whose addition can take place at any desired time during the course of the combination of the two treatment operations comminution and finish (with the exception of other processing stages) defined below in more detail, first in an inert liquid medium in a stirred ball mill, which is operated at a power density of >2.5 kW per liter of milling space and a peripheral speed of the stirrer of >12 m/s, under the action of a grinding medium having a diameter of ≤1 mm, until the X-ray index as a measure of crystallinity of the resulting prepigment particles is ≤9, b) subjecting this prepigment composition in the form of the suspension of the mill base thus obtained or, in the case of isolation of the intermediate after previous dispersion in an inert organic or inorganic liquid, to a solvent finish treatment at elevated temperature and c) then isolating the finished pigment preparation.