JPH0366354B2 - - Google Patents

Description

[Detailed description of the invention] Disazo pigment CI Pigment Yellow 83 (C.
I.21108) has become popular as one of the most important organic yellow pigments in the paint and plastics industry due to its good practical properties.

However, during large-scale industrial production, compared to scientifically pure disazo compounds, their migration behavior deteriorates to such an extent that they no longer meet the high practical requirements in the coatings and plastics sector. Things are often obtained. In the case of further disazo pigments obtained by coupling bis-diazotized 4,4'-diaminodiphenyl derivatives to astoacetylaminobenzene, it is also possible, inter alia, in the case of large-scale industrial processes, to obtain chemically pure disazo pigments. Compared to compounds, solvent, overcoat and migration fastnesses often result significantly worse. In this industrial process or otherwise in general, customary coupling methods are applied. For example, a small excess of the coupling component is generally used to ensure a quantitative reaction of the bisdiazonium compound. In this case, the coupling component is dissolved in an aqueous alkali solution in order to obtain a finely divided form capable of coupling and then precipitated again. Coupling is followed by heating of the pigment suspension in order to improve the filterability and to obtain a pigment form with soft granules and good tinting strength. These quality fluctuations are often also observed when the bisdiazonium salt solution and the alkyl solution of the coupling component are simultaneously introduced into the reaction vessel, possibly with a buffer solution already introduced.

The inventor has developed Pigment Yellow 83 and related disazo pigments of such purity that even in large-scale industrial production they always have satisfactory solvent and migration fastnesses, in particular high topcoat fastnesses and smudge fastnesses. I found a simple way to achieve this.

Therefore, the present invention provides a method for improving the practical properties of disazo pigments, which is characterized in that sulfite ions are added to the weakly acidic to neutral aqueous pigment suspension obtained during coupling, followed by heating. Regarding.

In order to improve the practical properties of the following disazo pigment, the present inventor has developed the general formula obtained during coupling. (In the formula, R ₁ and R ₂ are the same or different substituents selected from the group consisting of methyl, methoxy, ethoxy and chlorine, X is hydrogen or a chlorine atom, and m and n are independently 0 or We have discovered a method characterized in that sulfite ions are added to a weakly acidic to neutral aqueous suspension of a disazo pigment having a structure corresponding to (an integer from 1 to 3) and subsequently heated. .

The number of substituents R ₁ and R ₂ varies between 0 and 3, respectively. Preferably R ₁ and R ₂ represent methyl, methoxy or chlorine in the 2-, 4- or 5-position and x represents a hydrogen atom. Especially when R ₁ and R ₂ are 2
2 methoxy groups in the - and 5-positions and 4
A hydrogen atom in the - position and one in which x means a hydrogen atom are preferred (Pigment Yellow 83).

Sulfite ions can be present in gaseous form as sulfur dioxide or as aqueous solutions or as soluble sulfites, bisulfites or bisulfites, in particular sodium or potassium sulfite, sodium bisulfite or
It is added in dry or dissolved form as potassium, sodium disulfite or -potassium. The amount required can be determined by preliminary tests and is about 0.5 to 10% by weight, preferably 2 to 5% by weight, based on the pigment produced.

The pigment suspension is prepared in a conventional manner, for example, for several minutes to several hours.
It can be heated to a temperature of 50 to 100°C, preferably 80 to 100°C for about half an hour to two hours.
The heating can be carried out at temperatures above 100.degree. C. in conjunction with a thermal aftertreatment, optionally with the addition of auxiliaries, for example organic solvents. However, it is advantageous in this case to increase the temperature only gradually at first.

German patent application for thermal post-treatment advertising no.
If carried out according to No. 2302509, the pigment is first treated according to the invention, then stirred and reprecipitated in the presence of an alkali, then the isolated and washed neutral pigment is water and immiscible with water. or heated to temperatures above 100°C in a mixture consisting of only partially miscible organic solvents. This alkaline treatment is also described in German Patent Application No. 2302517.

The pigments are isolated in the customary manner from the aqueous suspension, optionally after separation of the organic solvent, washed free of salt, dried and ground.

Particularly in large industrial batches, the process according to the invention gives products of uniform quality and of satisfactory solvent, topcoat, transfer and smear fastness properties.

In the following examples, parts and percentages relate to weight, unless otherwise stated.

Example 1 50.6 parts of 3,3'-dichloro-4,4'-diaminodiphenyl are stirred with 600 parts by volume of water and 250 parts by volume of 5N hydrochloric acid, cooled to about 0° C. with ice and 52.5 parts of 40% sodium sulfite solution. bisdiazotization at 0 to 5°C. An acetic acid-containing suspension of 87 parts of 1-acetoacetylamino-2-methoxybenzene obtained by precipitation of a clarified bisdiazonium salt solution from an alkaline solution of an acetoacetate arylide at 20-25°C with thorough stirring. The pH value of the coupling suspension is maintained between 4.5 and 5.5. After the reaction of the bisdiazonium salt is complete, 5 parts of sodium sulfite are added to the suspension, heated to 90-95°C by introducing steam, kept at this temperature for 1 hour, and then cooled to 70°C to remove the solids. , wash until salt free, and dry. The yellow pigment obtained has very good overcoating and smear fastness properties.

Example 2 The procedure is carried out as described in Example 1, except that after the coupling has ended, an alkaline solution of 37.6 parts of a commercially available resin soap is added and the mixture is again precipitated to a pH value of 4-5. A yellow pigment is likewise obtained which has very good overcoat and bleed fastness properties.

Example 3 (comparative example) The procedure is carried out as described in Example 1, except that no sodium sulfite is added. The resulting pigments have significantly reduced overcoating and smudge fastnesses, especially in large industrial batches.

Example 4 25.3 parts of 3,3'-dichloro-4,4'-diaminodiphenyl are stirred with 500 parts by volume of 31% hydrochloric acid, cooled to about 0° C. by addition of ice, and 26.3 parts by volume of 40% sodium sulfite solution. to bisdiazotize.
Dilute with 400 parts by volume of water, destroy the slight excess of sulfite ions with amidosulfonic acid, and filter using a commercially available diatomaceous earth formulation as a clarifying agent. The bisdiazonium salt solution thus obtained was stirred thoroughly for 1 hour to form a finely dispersed suspension of 1-acetoacetylamino-2,4-dimethylbenzene.
It was prepared by precipitating an alkaline solution containing 43.5 parts of the coupling component in 300 parts by volume of water and 20 parts by volume of 33% caustic soda solution with 14 parts by volume of glacial acetic acid at 0 to 10°C. . The pH value of the suspension during coupling is maintained in the range 5.5 to 4.5 by dropwise addition of 6% caustic soda solution. 40% sodium bisulfite solution added to the pigment suspension after coupling
10 parts by volume were added, followed by heating to 98°C and 30 parts by volume.
It is kept at this temperature for minutes and the suspension is cooled to 70° C. and filtered.

The reddish-yellow pigments obtained after washing, drying and grinding have excellent overcoating fastness, for example in lacquers, even in large-scale industrial processes.

Example 5 32.2 parts of 2,2',5,5'-trichloro-4,4'-diamino-biphenyl were introduced into 80 parts by volume of 31% hydrochloric acid and the resulting hydrochloride paste was stirred overnight and cooled with ice. After addition, while stirring at 0 to 5℃
Gradually bisdiazotize with 26.3 parts of 40% sodium sulfite solution. The resulting bisdiazonium salt solution is filtered after addition of a commercially available diatomaceous earth formulation as a clarifying agent and diluted to 500 parts by volume with water. 44 parts of 1-acetoacetylamino-4-methoxybenzene are dissolved in 400 parts by volume of water and 20 parts by volume of 33% caustic soda solution, filtered using activated carbon and the solution is diluted with water to make up to 500 parts by weight. Both obtained solutions were simultaneously mixed with sodium acetate-acetic acid-buffer solution while stirring.
It was prepared from 50 parts by volume of 33% caustic soda solution and 40 parts by volume of glacial acetic acid, to which was added a 10% solution of the reaction product of 1 mole of oleyl alcohol and 30 moles of ethylene oxide. The flow is such that no excess of bisdiazonium salt can be detected. After coupling, 6 parts of sodium sulfite was added to the pigment suspension and heated to 98°C.
Stir for 1 hour at this temperature and then isolate the reaction product in the usual manner.

A brilliant yellow pigment is obtained, which is soft-
It has excellent migration fastness when mixed with PVC.

Example 6 (Comparative Example) The procedure is carried out as described in Example 5, except that no sodium sulfite is added. The resulting pigment has significantly worse migration fastness than the Example 5 pigment when incorporated into soft-PVC.

Example 7 32.2 parts of 2,2',5,5'-tetrachloro-4,4'-diaminobiphenyl are bisdiazotized as described in Example 5. 1-acetoacetylamino-2
- 51 parts by volume of methoxy-4-chlorobenzene are dissolved in 400 parts by volume of water and 20 parts by volume of 33% caustic soda solution, and subsequently 20 parts by volume of a 10% aqueous solution of the reaction product of 1 mol of stearyl alcohol and 25 mol of ethylene oxide. A finely dispersed suspension of the coupling components is prepared by precipitation with 14 parts by volume of 96% acetic acid in the presence of 96% acetic acid. A bisdiazonium salt solution is introduced into this for 1 hour with stirring, the pH value being maintained at about 4 to 3.5 by dropwise addition of 4N sodium acetate solution to the reaction mixture. Immediately after the end of coupling, 7 parts of potassium disulfite are introduced into the disazo pigment suspension, heated to 95°C by introducing water vapor, and at this temperature
Stir for an hour. After filtration a greenish-yellow pigment is obtained. This is washed salt-free, dried at 60°C and finally ground. This pale yellow pigment shows good migration fastness when incorporated into soft PVC.

Example 8 (Comparative Example) The procedure is as described in Example 7, except that no potassium disulfite is added. The resulting pigment has poor migration fastness after incorporation into soft-PVC.

Example 9 50.6 parts of 3,3'-dichloro-4,4'-diamino-biphenyl are bisdiazotized by the method described in Example 1. 43.5 parts of 4-acetoacetylamino-2-methoxybenzene and 43.5 parts of 4-acetoacetylamino-2,4-dimethylbenzene were dissolved in 800 parts of water by adding 40 parts of 33% caustic soda solution, and the alkaline solution was dissolved. The mixture of coupling components was clarified using activated carbon and precipitated by adding 28 parts by volume of 96% acetic acid with stirring after addition of 5 parts by volume of a 10% aqueous solution of the reaction product of 1 mole of stearyl alcohol and 20 moles of ethylene oxide. let
A solution of the bisdiazonium salt is introduced into the suspension obtained after addition of 100 parts of crystalline sodium acetate. Immediately after the coupling is finished, 8 parts of potassium sulfite are added and the pigment suspension is mixed with 1 part of water by introducing water vapor.
Heat to 95°C for an hour. After cooling to 60° C., the mixed coupling product is filtered with suction, washed salt-free with hot water, dried and ground. The yellow pigment thus obtained has excellent solvent resistance.

Example 10 (comparative example) The procedure is as described in Example 9, except that no potassium sulfite is added. The pigment obtained has a worse solvent resistance than the pigment obtained according to Example 9.

Example 11 50.6 parts of 3,3'-dichloro-4,4'-diaminodiphenyl are stirred with 600 parts by volume of water and 250 parts by volume of 5N hydrochloric acid, cooled to 0° C. with ice and 52.5 parts of 40% sodium nitrite solution. Bisdiazotize by volume at 0 to 5°C. The clarified bisdiazonium salt solution is heated at 20 to 25°C with thorough stirring to an acetic acid-containing suspension of 115 parts of 1-acetoacetylamino-4-chloro-2,5-dimethoxybenzene - this alkalinizes the acetoacetate arylide. The mixture obtained by precipitation from the solution flows into the solution, maintaining the pH value of the coupling suspension between 4.5 and 5.5. After the reaction of the bisdiazonium salt is complete, 5 parts of sodium sulfite are added to the suspension, heated to 90-95°C by introducing water vapor, kept at this temperature for 1 hour, then cooled to 70°C, filtered and freed from the salt. Wash and dry until clean. The resulting pigment is a completely perfect top coat.
and smudge fastness.

Coupling can also be carried out in the presence of a resin soap. In an otherwise identical procedure without the addition of alkali sulfites, alkalis bisulfites, alkalis pyrosulfites or sulfur dioxide, pigments are obtained which have significantly reduced overcoat and smear fastness, especially in large industrial batches. .

Example 12 In a modification of the process according to Example 11, a solution of the bisdiazonium salt prepared as in Example 11 and a solution of the coupling component are simultaneously added to a reaction vessel, in which acetic acid and a surfactant are already charged. − flows into. After coupling, potassium hydrogen sulfite was added to the crude pigment suspension in an amount of 5% based on the pigment yield, and the mixture was heated to 85-90°C by jacket heating.
Keep at this temperature for an hour. Work-up is then carried out as described in Example 11. The pigments obtained have completely satisfactory overcoat and transfer fastnesses.

Example 13 Example 11 is carried out, except that after cooling to 70° C. the suspension is made alkaline with caustic soda solution and then carried out according to Example 1 of German Patent Application No. 2302509. The pigments thus obtained in the form described there have high hiding power, good viscosity and high gloss. Furthermore, even in the case of large industrial batches, a uniform quality with excellent overcoat and smear fastness is obtained.

Claims (1)

[Claims] 1 In order to improve the practical properties of the following disazo pigment, the general formula obtained during coupling (In the formula, R ₁ and R ₂ are the same or different substituents selected from the group consisting of methyl, methoxy, ethoxy and chlorine, X is hydrogen or a chlorine atom, and m and n are independently 0 or A method characterized in that sulfite ions are added to a weakly acidic to neutral aqueous suspension of a disazo pigment having a structure corresponding to an integer from 1 to 3) and subsequently heated. 2 In the general formula, R ₁ and R ₂ are 2-, 4-, or 5-
methyl, methoxy or chlorine in position x
2. The method according to claim 1, wherein represents a hydrogen atom. 3 Disazo pigment is CI Pigment Yellow 83
The method according to claim 1 or 2, wherein: 4. The method according to any one of claims 1 to 3, wherein sulfite ions are added in the form of sulfur dioxide or soluble sulfites, bisulfites or disulfites. 5 Pigment suspension for half an hour to two hours, 50 to 100
The method according to any one of claims 1 to 4, wherein the method is heated to a temperature of .degree.