GB2123845A

GB2123845A - Crystalline monoazo dye and its production

Info

Publication number: GB2123845A
Application number: GB08316289A
Authority: GB
Inventors: Yoshihiro Narita; Akira Kajikawa; Toshio Shintani
Original assignee: SYNTHETIC DYESTUFF RES ASS; Research Association of Synthetic Dyestuffs
Current assignee: SYNTHETIC DYESTUFF RES ASS; Research Association of Synthetic Dyestuffs
Priority date: 1982-06-21
Filing date: 1983-06-15
Publication date: 1984-02-08
Also published as: JPS6340451B2; GB2123845B; CH653356A5; DE3322301A1; GB8316289D0; JPS58225156A

Abstract

A mono azo dye comprises a crystalline compound represented by formula: <IMAGE> The dye has an X-ray diffraction pattern with peaks at angles (2???) of 20.0 DEG and 7.5 DEG . The dye is produced by diazotizing 2,4-dinitro-6,2,4-dinitro-6-bromo- aniline, coupling the diazo compound with 3-acetylamino-N,N-diethyl- aniline (e.g. at 0 DEG C), preferably filtering off the blue dye as a cake, and subjecting to heat treatment at 50 to 200 DEG C. The mono azo dye is used in dispersion or as a paste for dip dyeing or print dyeing of polyester fibres and blends thereof; it withstands dyeing at high temperature, e.g. 130 DEG C, to provided dyed fibres having excellent fastness properties.

Description

SPECIFICATION Crystalline mono azo dye and its production The present invention relates to a specific mono azo dye in crystalline form, and a process for its production.

Recently, various improvements have been made in dyeing methods, and a liquid flow dyeing method which can dye large amounts of fibres at one time by dyeing methods, for example, beam dyeing, cheese dyeing or package dyeing, has often been adopted. These dyeing methods are of the type in which a dye dispersion is forcedly passed through the interior of minute fibrous layers rolled over and over again and, therefore, it is desired that dye particles in the dye dispersion be finely divided, stable particles. If the dye particles grow in size during dyeing, it becomes difficult for the particles to permeate into the interior of the fibrous layers, so that problems arise, namely that the shade of color is different between the inner layer and the outer layer of the fibrous layers and the fastness is reduced.

Accordingly, it is required that dyes used for such dyeing methods have good dispersibility in a dyeing bath and at the same time, the dispersibility be not decreased over a wide temperature range of from room temperaure to a high temperature at which dyeing is actually effected. However, dispersibility of a dye in a dyeing bath is generally poor at high temperatures and, in same cases, dye particles aggregate during dyeing, and, as a result, dyeing is sometimes non-uniform.

The structural formula of the mono azo dye in accordance with the present invention is

This is known from, for example, British Patent Specification No. 1 ,050,675 (formula (III), dye 60). The preparative method used therein does not include any heat treatment at 500C or more after the coupling reaction in the cold for preparation of a dye, and it is believed that the dye thus obtained is in the amorphous (non-crystalline) state. When this blue mono azo dye prepared in thus known manner is used for the dyeing of fibres at high temperatures, the state of dispersion of the dye particles in the dyeing bath is poor so that it is difficult to obtain a dyed product having a uniform dyed color.

We have therefore investigated various methods for improving the dispersion stability of the mono azo dye having the above formula at high temperatures and have found that the mono azo dye described above exists in at least two modifications; one of these is unstable to heat, and is obtained by a conventional synthesis reaction (hereafter referred to as a-type modification) and another is very stable even at a high temperature in a dyeing bath (hereafter referred to as p-type modification).

Accordingly, the present invention provides a mono azo dye of the above structural formula, in crystalline form. This compound is characterised by an X-ray diffraction pattern showing the strongest peak at diffraction angles (26) of about 20.00 and 7.50.

The process of the present invention for producing the mono azo dye comprises diazotizing 2,4dinitro-6-bromoaniline, coupling the resulting diazo compound with 3-acetylamino-N,N-diethylaniline and then subjecting the resulting dye to heat treatment at a temperature of from 50 to 2000 C.

In the accompanying drawings, Figures 1 and 2 are graphs (X-ray diffraction patterns) obtained by recording the diffraction spectrum by irradiating with Cu-Ka rays using a proportional counter for measurement by a pulverulent X-ray diffraction method, wherein the abscissa represents diffraction angle (26) and the ordinate represents diffraction intensity.

Figure 1 shows the p-type modification of the present invention; this is obviously crystalline and possesses the strongest peaks at diffraction angles (26) of about 20.00 and about 7.50 and further posseses strong peaks at about 25.40, about 25.10, about 22.80, about 21.6 and about 11.6 , following the strongest peaks. In addition, the p-type transformation possesses weak peaks at diffraction angles (20) of about 25.8", 24.3", 24.00 and 23.40, while these are supplemental characteristics. Thus, it is clear from Figure 1 that the dye of the present invention has a characteristic crystalline structure.

On the other hand, Figure 2 shows the a-type.modification. Only peaks having a gentle rise and fall are seen, which indicates that the type modification is amorphous, not crystalline. Thus the dye of the invention is distinguishable over the known form of dye from the X-ray diffraction patterns.

The crystalline dye of the present invention can be obtained as follows: 2,4-dinitro-6-bromoaniline is diazotized in a conventional manner followed by coupling with 3-acetylamino-N,Ndiethylaminine, and the monoazo compound having the structural formula shown above which has an amorphous a-type form is subjected to heat treatment at a temperature of from 500 to 2000C, preferably 600 to 1300 C, to obtain the desired Aype modification. If the temperature in the heat treatment is lower than 500 C, it is impossible to effectively convert the mono azo compound from the ce-type to the P-Wpe modification.The time required for the heat treatment somewhat varies depending upon the type of treatment and temperature of treatment, but is generally in the range of from about 2 to about 5 hours.

Preferred heat treatments are as follows: (1) subjecting the product obtained by the coupling to heat treatment directly; (2) once filtering the reaction mixture to recover a cake, then suspending the cake in an aqueous medium and subjecting the suspension to heat treatment; (3) isolating a cake from the reaction mixture and subjecting the cake to heat treatment whilst preparing a dye dispersion composition in the presence of a dispersing agent; (4) isolating a cake from the reaction mixture and then subjecting the cake to heat treatment in a gaseous phase.

Of those methods, method (2) described above is particularly preferred.

Fibers which can be dyed with the mono azo compound of the present invention include polyester fibres composed of polyethylene terephthalate, a polycondensate of terephthalate, a polycondensate of terephthalic acid and 1 ,4-bis(hydroxymethyl)cyclohexane, and mixed spun products and mixed woven products of natural fibres such as cotton, silk or wool and the polyester fibres described above.

Dyeing of fibres using the mono azo compound of the present invention can be generally performed as follows. A dye cake is finely dispersed in an aqueous medium generally in the presence of a dispersing agent such as a condensate of naphthalenesulfonic acid and formaldehyde, a higher alcohol sulfuric ester or higher alkylbenzenesulfonic acid salt, to prepare a dyeing bath or a printing paste. Dip dyeing or print dyeing can be performed using the thus prepared dyeing bath or printing paste. In the case of dip dyeing, the mono azo compound is used in, for example, a high temperature dyeing method, a carrier dyeing method or thermosol dyeing method. In the present invention, the mono azo compound having the structural formula shown above may also be employed in combination with dyes having other structures.Further, various additives may also be added whilst preparing a dispersion of the dye.

As described above, in the case of dyeing with the mono azo compound of the present invention of the '3-type modification, the present invention has the effects that not only fibres are dyed uniformly and stably but also the thus obtained dyed products have high fastness since dye particles are dispersed uniformly and stably even in a dyeing bath at high temperature.

The present invention will be explained in more detail by reference to the following example.

Example In a glass-made reactor equipped with a stirrer, 1 80.3 g of 98 weight % sulfuric acid was charged and 16.6 g of sodium nitrate was added thereto. The mixture was stirred at a temperature of 700C and completely dissolved to prepare nitrosyl sulfate. Then, 60.0 g of 2,4-dinitroaniline was added to the solution followed by diazotization for 3 hours at a temperature of 200 C.

Separately, 47.2 g of 3-acetylamino-N,N-diethylaniline was dissolved in 500 g of a 2 weight % aqueous sulfuric acid solution. The reaction mixture of the above diazotization was dropwise added to the resulting solution with stirring over 2 hours at a temperature of OOC to perform a coupling reaction.

After completion of the reaction, the mixture was filtered and 104 g of a dye cake of a blue color was recovered. A part of this cake was analyzed with respect to crystal transformation by an X-ray diffraction method, which indicated that the cake was an amorphous type modification having the Xray diffraction pattern as shown in Figure 2.

Subsequently, this dye cake was dispersed in 1,000 ml of water and the dispersion was heat treated with stirring for 5 hours at a temperature of 900 C. After completion of the heat treatment, the cake was filtered and a part of the cake was analyzed with respect to crystal structure by an X-ray diffraction method. The results indicate that the cake was a p-type modification having the X-ray diffraction pattern shown in Figure 1.

Thermal stability test: A thermal stability test of a dispersion of the dye was performed by the following method, using the dye cake having a type modification or an cr-type modification obtained as described in the Example.

2 g each of solid dye, a condensate of napththalenesulfonic acid-formaldehyde, a condensate of naphthalenesulfonic acid cresolsulfonic acid-formaldehyde and a lignin sulfonic acid condensate was dispersed in water. After finely dividing each in a sand grinding mill, the dispersion was spray dried to obtain a dye composition.

In 300 ml of water, 1 g of the thus obtained dye composition and 0.3 g of a mordant (made by Nikka Chemistry Co., Ltd., marketed under the trademark "Sansolt 7000") were dispersed and the pH was adjusted to 5 with ammonium sulfate and acetic acid. After subjecting the dispersion to heat treatment at 1 300C for 60 minutes, the reaction product was quenched to 800C and then suction filtration was performed using a quantitative filter paper (made by Toyo Filter Paper Co., Ltd., No. 5A).

The amount of the aggregated matter on the surface of the filter paper was evaluated in accordance with the following criteria.

Grade State on the surface of filter paper 4 Aggregates were hardly seen.

3 Aggregates were slightly seen.

2 Aggregates were seen in large amounts.

1 Aggregates were seen in much larger amounts.

The results are as follows.

Grade of observed dye Crystal modification aggregates Example ,B-Type (crystalline) 1 Comparison Example type (amorphous) 4

Claims

1. A mono azo dye comprising a crystalline compound represented by the following structural formula:

2. A mono azo dye as claimed in Claim 1, wherein said crystalline compound has the strongest peaks at diffraction angles (20) of about 20.00 and about 7.50 in an X-ray diffraction pattern.

3. A mono azo dye as claimed in Claim 2, wherein said crystalline compound shows the second strongest peaks at diffraction angles of about 25.40, about 25.1 0, about 22.80, about 21.60 and about 11.60.

4. A mono azo dye as claimed in Claim 1, which has an X-ray diffraction pattern substantially as shown in Figure 1 of the drawings.

5. A process for producing a mono azo dye as claimed in Claim 1, 2 or 3, which comprises diazotizing 2,4-dinitro-6-bromoaniline, coupling the resulting diazo compound with 3-acetylamino N,N-diethylaniline and then subjecting the resulting dye to heat treatment at a temperature of from 50 to 2000C.

6. A process as claimed in Claim 5, wherein the heat treatment is performed at a temperature of from 60 to 1 300C in an aqueous medium.

7. A process as claimed in Claim 5 or 6, wherein the dye is formed into a cake before the heat treatment.

8. A process as claimed in Claim 7, wherein the cake is suspended in an aqueous medium and the suspension is subjected to the heat-treatment.

9. A process as claimed in Claim 5, substantially as hereinbefore described in the Example.

1 0. A method of dyeing, wherein fibres are dyed with a dispersion or paste of a dye as claimed in Claim 1, 2, 3 or 4 or made by a process as claimed in any of Claims 5 to 9.

11. Fibres dyed by the method of Claim 10.