CH626118A5 - Process for preparing aqueous dispersions of azo dyes - Google Patents

Description

626118

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PATENT CLAIM Process for the preparation of aqueous dispersions of azo dyes which are free from water-solubilizing groups, characterized in that, for coupling, the aqueous solution or dispersion of a diazotized amine is combined with an aqueous solution or suspension of a coupling component in the presence of nonionic surfactants, from which obtained finely divided dispersion by a membrane separation process, part of the water and at least part of the inorganic salts formed in the preparation of the dyes and selects the components so that the dye is free of water-solubilizing groups.

The invention relates to a process for the preparation of aqueous dispersions of azo dyes which are free from water-solubilizing groups, characterized in that, for coupling, the aqueous solution or dispersion of a diazotized amine is combined with an aqueous solution or suspension of a coupling component in the presence of nonionic surfactants , a part of the water and at least part of the inorganic salts formed in the preparation of the dyes are separated from the finely divided dispersion obtained by a membrane separation process and the components are selected so that the dye is free from water-solubilizing groups. Dispersion dyes and preferably pigments are suitable as water-insoluble azo dyes. Dyes of this type are listed in the Color Index, 2nd Edition, Part II, for example under the CI numbers 11855,12770, 26090,12700,11080, 11100,11110,11130 (disperse dyes) and 11680, 11710, 21100,11660, 11730, 21090, 21100, 12730, 20045 and 12460 (pigments).

Monoazo pigments of the formula are particularly preferred

CONH-1

R

R

where R 1 and R 2 are hydrogen, C 1 -C 4 -alkyl, halogen, C 1 -C 4 -alkoxy, nitro, phenylaminosulfonyl, carbo-C 1 -C 4 -alkoxy or in the adjacent position together - CO —NH —CO— or -NH-CO-NH- and

R3, R4 and R5 are hydrogen, Ci-C4-alkyl, Ci - C4-alkoxy, halogen or two adjacent radicals together

CO-NH-CO or NH-CO-NH

mean.

Halogen means chlorine in particular.

Pigments of the formula I are very particularly preferred in which R 1 is nitro, R 2 is methyl, methoxy or chlorine, R 3 is hydrogen, chlorine or methoxy and R 4 and Rs are hydrogen.

The process according to the invention can be used to produce aqueous dispersions of individual dyes or of dye mixtures by means of a mixing coupling. Dye mixtures can of course also by

Mixing already prepared dye dispersions of individual dyes can be obtained.

Ethylene oxide adducts and adducts of propylene oxide and ethylene oxide are preferably used as nonionic surfactants. Ethylene oxide adducts are reaction products of 3 to 60 moles of ethylene oxide and, for example, alkylphenols, long-chain alcohols, long-chain amines or long-chain carboxylic acids and with polypropylene glycols. A large part of these compounds is described in N. Schönfeldt, surface active addition products of ethylene oxide, Wissenschaftliche Verlagsgesellschaft Stuttgart, 1959. Adducts of 10 to 20 mol of ethylene oxide with nonylphenol, phenylethylphenol or benzylhydroxydiphenyl and, in particular, oxyethylation products with 10 to 20 mol of ethylene oxide of compounds of the recurring structural unit of the formula are preferred

OH

-CH

CH - N-R-N-

R

wherein

R is a C2 — Cn-alkylene radical which is optionally interrupted by O, S, NR4, CO, arylene or cycloalkylene or a C5-C7-cycloalkylene radical,

Ri and R2 independently of one another hydrogen, Ci - Ct-alkyl, C2-C4-hydroxyalkyl or together C2-C4-alkylene R3 hydrogen, Ci - Ci2-alkyl, Cs-C7-cycloalkyl, aryl, aralkyl, halogen, hydroxy, Ci - Cis-alkoxy, carboxy or Ci - Ci8-alkoxycarbonyl and

R4 is Ci - C4-alkyl or C2-C4-hydroxyalkyl.

Other non-ionic surfactants include Fatty acid esters of polyhydric alcohols such as glycerol, sorbitol, pentaerythritol as well as glucose and sucrose. Also optionally substituted fatty acid amides and polyamines.

The nonionic surfactants are expediently added to one of the two components in the preparation of the azo dyes. This is followed by the azo coupling which is carried out in the customary manner, the starting product mixed with the surfactant being present in dissolved or dispersed form. The surfactant is preferably added to the dissolved coupling component, which is then precipitated by acidification with vigorous stirring and is then converted to the dye by adding the diazotized amine.

In this way, a finely divided dye dispersion is obtained directly, in which the particle size of the azo dyes is 0.01 to 5 ix, preferably 0.05 to 3 11.

The nonionic surfactants are e.g. in amounts of 20 to 200%, preferably 50 to 100%, based on the dye.

The dispersions obtained in this way are largely freed from concentrated substances and concentrated by a membrane separation process. Such membrane separation processes are described in the literature, for example in U.F. Franck, Dechema-Mono-graphie 75,1452 to 1485, 9/37 (1974) described in detail as reverse osmosis, ultrafiltration, dialysis or electrodialysis.

Pressure permeation is preferably used, in which the passage of water and solutes, mainly inorganic salts, which have formed during the coupling, through the semipermeable membrane takes place under the driving force of a hydrostatic pressure which exceeds the osmotic pressure.

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626118

The pressure permeation for the method according to the invention can be carried out on all commercially available pressure permeation devices. Such devices can e.g. be designed as a plate-frame module, tubular module, hose module, hollow fiber module or as a hollow fine fiber module.

Membranes which can be used according to the invention and are built into the devices described above are e.g. those made from cellulose, cellulose di- or triacetate or those made from synthetic polymers such as polyamides, polyolefins and polysulfones. Membranes made of porous glass or heavy metal oxides, so-called “dynamic membranes”, can also be used. The membranes can be pore or solution diffusion membranes.

Membranes of the aforementioned type are described, for example, in U. F. Franck, (see page 4) and Hwang; Kammermeyer, Membranes in Separation (Techniques of Chemistry) Vol. 7, 1975, Wiley, New York.

In simple preliminary tests, it must be determined which separation limit the membrane must have in order to predominantly, preferably completely, retain the finely divided pigment produced by the process according to the invention and to let most of the dissolved compounds to be separated off, preferably completely. Depending on the type of membrane, the pressure permeation is generally carried out at temperatures between 10 and 90 ° C., preferably at room temperature. The pH of the dispersion to be subjected to pressure permeation is not critical insofar as suitable membranes are available for all pH ranges. The pressures used are around 0.5 to 60 bar depending on the type of membrane and the pressure permeation device.

The salt content is expediently reduced to less than 60% of the dye content, preferably to less than 5% of the dye content. Water is generally separated to such an extent that the dye content of the finished dispersion is 5-60% by weight, preferably 8-20% by weight.

In addition to the nonionic dispersants, the pigment dispersions can also contain other conventional additives such as agents which prevent drying, for example glycol or diglycol.

In contrast to the known processes for the production of aqueous pigment dispersions, in which the pigments with the nonionic or anionic dispersants and optionally water have to be comminuted in complex comminution units such as ball mills, kneaders, roller mills or bead mills in order to achieve a fine distribution which is sufficient for the application. The process according to the invention gives finely divided pigment dispersions without any comminution work, which can be used universally and are outstandingly suitable for the production of emulsion paints based on polyvinyl acetate, polyvinyl acetate copolymers, styrene-butadiene mixed polymers, polyvinyl propionates, acrylic acid and metha- acrylic acid ester polymers, saponified alkyd resins and oil emulsions; as well as for the production of wallpaper paints based on cellulose derivatives, such as methyl cellulose, hydroxymethyl cellulose, carboxymethyl cellulose and for the production of printing inks which primarily contain saponified natural resins such as shellac, saponified water-soluble synthetic resins or acrylate binder solutions.

It is already known from German Offenlegungsschrift 2,358,080 that aqueous dispersions of water-insoluble azo dyes can be prepared by coupling the dyes in the presence of an anionic dispersant and then separating at least some of the inorganic salts of the dispersion by a membrane separation process. The disadvantage of this process is that the anionic dispersants do not provide the required fine distribution of the dye after the coupling process and the aqueous dispersion must also be subjected to an additional mechanical grinding treatment in order to reduce the particle size of the dye to the desired value. In addition, pigment dispersions with anionic dispersants have the major disadvantage that they can be distributed so poorly in white dispersions based on polyvinyl alcohol, styrene-butadiene copolymers, polyvinyl propionates, acrylic acid and methacrylic acid ester polymers that a rub-out effect is obtained.

example 1

26 g of acetoacetic anilide are dissolved in a mixture of 200 ml of water and 16 ml of 40% sodium hydroxide solution. About 100 g of ice and 37 g of an emulsifier were added to this, which was prepared by reacting benzylhydroxybiphenyl with 15 mol of ethylene oxide. The acetoacetic anilide is then precipitated from this solution, with vigorous stirring using a grid stirrer, by the rapid addition of 10 ml of glacial acetic acid, and 11 g of sodium acetate are added. A diazonium salt solution, which is prepared as follows, is added to this dispersion, with stirring:

22 g of 3-nitro-4-aminotoluene at 0-5 ° C in a mixture consisting of 100 ml of water, about 100 g of ice and 40 ml of hydrochloric acid (19.5 ° Bé) by adding 10 g of sodium nitrite in 40 ml of water diazotized.

A yellow pigment dispersion is obtained, which is stirred for a further 12 hours and then adjusted to pH 6-7. The pigment particles have a size of 0.2-1 (x. This dispersion is cleaned from inorganic salts and concentrated by one of the following methods:

a) The dispersion is concentrated at room temperature and an excess pressure of 3 bar in an ultrafiltration system from Amicon, type TCF10. An anisotropic membrane made of cellulose acetate with a molecular separation limit of approx. 60,000 is used. The dispersion is concentrated to a dye concentration of 10% under the conditions mentioned. The filtration current density I is averaged over the entire concentration at 4001 per-meat per m2 membrane area and day (l / m2d). The salt concentration in the dispersion after the concentration is 4.5%.

b) The dye dispersion is first cleaned of the NaCl contained under the same conditions as under a). For this purpose, an amount of fresh water, which corresponds to 6 times the initial volume of the dispersion, is continuously added to the dispersion, in the amount that permeate is removed. After this cleaning, the desalted dispersion is concentrated to a dye content of 15%. A filtration current density of 1600 l / m2d results over the entire test. The concentrated dispersion contains only 0.2% NaCl, based on the dye content.

c) Instead of the fresh water used in b) for cleaning the dispersion of NaCl, a 3.9% solution of a nonionic surfactant is used. As in Example b), the NaCl content is reduced to <1%, based on the dye, after cleaning with 6 times the initial volume and subsequent concentration. As in Example b), the filtration current density is 1600 l / m2d.

d) The dye dispersion is concentrated at room temperature and an excess pressure of 20 bar in a reverse osmosis laboratory system according to the thin-channel principle. The anisotropic cellulose acetate membrane used has a nominal molecular cut-off of 6000. The dispersion is concentrated to a dye content of 15% under the conditions mentioned. The filtration current density reached s

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626118

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is 400 l / m2d. The salt content of the dye dispersion after concentration is 4%.

e) Under the same conditions as in d), the dispersion is desalinated with 6 times the initial volume of fresh water. As in b), the fresh water is continuously added to the mass as the permeate is drawn off. becomes. The dispersion is then concentrated to 10% dye. The filtration current density achieved over the entire test is 700 l / m2d. The salinity is <1%. io

This process gives pigment dispersions that are very suitable, for example, for coloring aqueous paints based on plastic dispersions, for coloring wallpaper paints based on plastic dispersions and cellulose derivatives, and for coloring printing inks based on saponified, water-soluble natural and synthetic resins .

Example 2 20

31 g of acetoacetic acid 2-chloroanilide are dissolved in 400 ml of water and 20 ml of 40% sodium hydroxide solution. About 100 g of ice and 57 g of an emulsifier are added, the production of which is described in the following paragraph. The acetoacetic acid 2-chloroanilide is then precipitated from this solution with vigorous stirring using a grid stirrer for 2 s by rapidly adding 15 ml of glacial acetic acid. A diazonium salt solution, which is prepared as follows, is added to this dispersion, with stirring:

A solution of 25 g 4-chloro-2-nitroaniline, 100 ml glacial acetic acid 30 and 37.4 ml hydrochloric acid (30%) is added to a solution of 10 g sodium nitrite in approx. 250 ml ice water and at 5-7 ° C diazotized.

A yellow pigment dispersion is obtained, which is stirred for a further 12 h and then adjusted to pH 7. By 35

Using the separation processes described in Example la-e, pigment dispersions are obtained which are very suitable for dyeing aqueous paints and printing inks.

Production of the emulsifier:

110 g of nonylphenol, 58 g of hexamethylene diamine and 30 g of paraformaldehyde were mixed at 50-60 ° C. and stirred at 90 ° C. for 5 hours. The water of reaction was then distilled off in vacuo. 36 g of the condensation product thus obtained were reacted with 264 g of ethylene oxide at 120-140 ° C. in the presence of 0.4 g of powdered potassium hydroxide.

Example 3

30.5 g of acetoacetic acid-o-anisidide are dissolved in 500 ml of water and 15 ml of 40% sodium hydroxide solution. About 100 g of ice and 57 g of the emulsifier used in Example 2 are added. The acetoacetic anilide is then precipitated from this solution with vigorous stirring using a grid stirrer by rapidly adding 15 ml of glacial acetic acid. A diazonium salt solution, which is prepared as follows, is added to this dispersion with stirring:

24.4 g of 5-nitro-2-aminoanisole are stirred with 200 ml of water and 50 ml of hydrochloric acid (30% strength) and, after adding about 100 g of ice, diazotized with 35 ml of a 30% strength sodium nitrite solution at 10-15 ° C .

A yellow pigment dispersion is obtained, which is stirred for a further 12 hours and then adjusted to pH 6-7. By using the separation processes described in Example la-e, pigment dispersions are obtained which are very suitable for dyeing aqueous paints and printing inks.

Example 4

Dispersions with a similarly good fine distribution are obtained if, in Examples 2 and 3, instead of the emulsifier specified there, an emulsifier obtained by reacting benzyl-hydroxy-biphenyl with 15 mol of ethylene oxide is used. By using the separation processes described in Example la-e, pigment dispersions are obtained which are very suitable for dyeing aqueous paints and printing inks.

B