CS269945B1 - A process for preparing the pigment form of the isomer of naphloylenebenzimldazole - Google Patents

Abstract

The pigment form is prepared by hydrolysis of the KOC.rl. or NaOC.H, adduct in water* 2 5 2 5 or in water containing polyethylene oxide wax or a chlorobenzene solution of polyethylene oxide wax« KOC2^íj or NaOC2H^ adduct »· is prepared by heating in ethanol β KOH or NaOH in the presence of a small amount of water.

Description

The subject of the invention is a method for preparing a pigment form of the cis isomers of naphthoylenebenzimidazole, characterized by a yield and a bright yellow shade of red color.

Condensation of 1,4,5,8-naphthalenetetracarboxylic acid with 1,2-diaminobenzene produces a mixed naphthalenebenzylidene dye, which is used as a vat dye or is separated into a trans and cis isomer and these isomers are also used as vat dyes or are processed into pigments. Due to their stability at high temperatures, pigments have recently found particular use, especially in dyeing polypropylene fibers. The different solubility of their KOH addition compounds, prepared by heating the mixed dye in a medium containing water, ethanol and KOH, is usually used to separate the trans and cis isomers. The solid KOH addition compound of the trans isomers is separated from the soluble KOH addition compound of the cis isomers and processed into a vat dye or pigment. According to the literature, the red pigment form of the cis isomers is achieved by hydrolyzing the purified aqueous alcoholic alkaline mother liquor with p-toluenesulfonic acid after separation of the KOH adduct of the trans isomer and after distillation of the ethanol. The pigment is also obtained by processing the alpha modification of cis naphthoylenebenzimidazole with a mixture of water, organic solvent, alkali metal hydroxide and surfactant at 100 to 250 °C or, more energy-efficiently, at a temperature of up to 80 °C, when the alpha modification is also treated with a mixture of water and organic solvent (dimethylformamide, dimethylsulphide, monoethylene glycol monoethyl ether, ethanol, acetone, trichlorobenzene), or 1 alkali metal hydroxide and surfactant and the solvent is then removed, or the reaction mixture is diluted with water or an aqueous solution of a mineral or organic acid. The beta modification of the cis isomers is formed. The beta modification is also obtained by very long grinding of the alpha modification with NaCl, KC1, CaCl„, Na SO , K SO,, Na_CO_, K.CO_ or * Λ Tm ύ «G w & J

NaOAc and hydrocarbons, halogenated hydrocarbons or ketones. Another method of preparing the pigment form of beta modification consists in the hydrolysis of the slightly yellowish NaOH precipitate of the cis naphthoylenebenzimidazole adduct in water containing a chlorobenzene solution of polyethylene oxide wax (solidification temperatures 9o to 94 °C, densities at 2o °C 0.91 to 0.92).

In all examples, the pigment is therefore prepared either by alpha modification processing, either by grinding in hydrocarbons or ketones in the absence of water, or by other processing in the presence of water, or the pigment is formed by hydrolysis of a KOH or NaOH adduct formed in an environment containing predominantly or a greater amount of water.

Known processes produce pigments of alpha or beta modification of cis naphthoylenebenzimidazole, which form varnishes of a turbid red color with a blue tint, dyeing a polypropylene fiber in the same shade.

It has now been found that a cis naphthoylenebenzimidazole pigment with a higher yield, a brilliant yellow shade of red, coloring polypropylene fiber, is formed when, in water or in water-containing polyethylene oxide wax or a chlorobenzene solution of polyethylene oxide wax (with a freezing point of 38-2 °C, density at 20 °C of 1.15 to 1.17, trade name . for example Apretár RV or Apretár P) the KOC^Hg or NaOC^Hj adduct of cis naphthoylenebenzimidazole, a crystalline orange substance with a yellowish shade, which is formed by heating cis isomers of naphthoylenebenzimidazole and ethanol containing a maximum of 7% water, preferably by heating with 96% ethanol and solid KOH or NaOH to 65 max. 70 °C. Hydrolysis in water or in water containing polyethylene oxide wax or a chlorobenzene solution of polyethylene oxide wax is carried out at 2o to 75 °C,

In contrast to the process in which the NaOH addition compound of the cis isomers is hydrolyzed. arising from an aqueous medium from which most of the ethanol has been previously removed by distillation. The KOCjHg (or NaOCjHg) addition compound of the cis naphthoylenebenzimidazole is now hydrolyzed. The preparation of the pigment form of the cis naphthoylenebenzimidazole by hydrolysis of the KOCjHg (or NaOCjHg) addition compound of the cis naphthoylenebenzimidazole in water or in water containing polyethylene oxide wax or a chlorobenzene solution of polyethylene oxide wax is the subject of the present invention.

The preparation procedure is further explained by examples.

CS 269945 Bl

Example 1.

Io g of dried alpha modification of cis naphthoylenebenzimidazole, 89 ml of 96% ethanol and g of solid KOH were heated to 65 to 70 °C with stirring and stirred at this temperature for 10 minutes. After cooling, the orange precipitate was filtered off and sucked off sharply, which was introduced in portions into 2oo ml of water at 5 °C, containing 0.5 g of polyethylene oxide wax with the trade name Apretár RV, dissolved in 2 ml of chlorobenzene. After stirring, the mixture was stirred for 3 hours at 70 to 75 °C, the cooled mixture was filtered, the filter cake was washed with ethanol and water. After drying at 80 to 90 °C, 8 g of pigment was obtained, coloring polypropylene silk in a bright red color with a yellow tint.

Example 2.

lo g of dried cis isomer of naphthoylenebenzimidazole.

9o ml of 96% ethanol and lo g of solid NaOH were heated to 65 to 7o °C for 6o minutes with stirring. After cooling, the suspension was filtered, the sharply suctioned cake of the orange-yellow precipitate of the adduct was introduced in portions into loo ml of ice-cold water containing o.5 g of polyethylene oxide wax of the trade name Apretár P dissolved in 2 ml of chlorobenzene, the mixture was stirred for 15 minutes with cooling and then at room temperature for 8 hours. After filtration, washing with ethanol and water and drying at 8o to 9o °C, 8 g of a very bright red pigment with a yellow tint were obtained.

Example 3.

The KOCljlij adduct was prepared as in Example 1 and the adduct cake was introduced in portions into ice-cooled water at 5°C containing 0.4 g of polyethylene oxide wax. The mixture was stirred at room temperature for 5 hours, the pigment was filtered off, washed with water and dried at 80°C.

Example 4.

The NaOC2Hg adduct was prepared as in Example 2 and the adduct cake was introduced into water in portions. The mixture was stirred for 3 hours at room temperature, the pigment was filtered off and dried at 80°C.

Claims (1)

SUBJECT OF THE INVENTION A method for preparing the pigment form of the naphthoylenebenzimidazole isomer, characterized in that a KOCgHg or NaOC ₂ Hg addition compound of cis naphthoylenebenzimidazole is prepared by heating with ethanol containing a maximum of 7% water, preferably by heating with 96% ethanol and solid KOH or NaOH to a temperature of 65 to 70 °C and this is hydrolyzed in water or in water containing polyethylene oxide wax or a chlorobenzene solution of polyethylene oxide wax at a temperature of 20 to 75 °C.