Preparation process of reddish brown reactive dye

Abstract

The invention belongs to the field of reactive dye synthesis, and discloses a preparation process of a reddish brown reactive dye, which comprises the following steps: diazotizing 2-naphthylamine-4, 6, 8-trisulfonic acid, coupling with 1-naphthylamine-7-sulfonic acid to obtain a first-couple material, diazotizing the first-couple material again, coupling with m-toluidine to obtain a second-couple material, refining the second-couple material to obtain a color base, and drying to obtain the reddish brown reactive dye. Carrying out primary condensation on cyanuric chloride and 2, 5-aniline disulfonate to obtain a primary condensation material, carrying out secondary condensation on the primary condensation material and a color base, and filtering the secondary condensation slurry to obtain the reddish brown reactive dye primary stock. The preparation process provided by the invention is stable and low in spray drying energy consumption, and the prepared primary pulp has the advantages of high purity and high solid content, and is excellent in solubility and high in fastness to washing.

Description

Technical Field

[0001] This invention belongs to the field of reactive dye synthesis, and specifically relates to a preparation process for a reddish-brown reactive dye. Background Technology

[0002] Dyes using red, yellow, and blue (navy cyan) as the three primary colors can be blended in different proportions to create a wide variety of colors, such as orange, green, purple, and even black. Therefore, the production scale of these three colors is massive, occupying a large market share. However, this very fact limits the investment in research and development of other colors, resulting in fewer varieties and fewer single-color options, most of which are blends of the three primary colors. For example, brown dyes require the simultaneous blending of all three primary colors (as disclosed in Chinese patent CN1321159C, which describes a reactive yellow dye and its blended brown reactive dye, obtained by preparing a reactive yellow dye and then blending it with reactive black and reactive red). Compared to other varieties, brown dyes are more prone to problems due to differences in dye structure, I / O values, and solubility, leading to poor compatibility between components, resulting in varying dyeing rates, different shades, and color differences and defects on the fabric surface. Furthermore, currently, there are few varieties of brown single-color reactive dyes, and their processing technologies are lacking.

[0003] The invention patent application (CN 101565553A) discloses a series of brown dye structures and their preparation methods, which can be used for printing and dyeing of cellulose fibers. They have the advantages of bright color and high fixation rate, but the preparation process is relatively long. The raw pulp needs to be processed by plate and frame filter and nano-membrane filtration, which takes a long time, generates a large amount of wastewater, and the resulting product has general solubility and limited application range.

[0004] Therefore, providing a process for preparing a brown monochrome reactive dye with excellent overall performance is of great value and significance. Summary of the Invention

[0005] The purpose of this invention is to provide a preparation process for reddish-brown reactive dyes, which solves the problems of low conversion rate, high by-products and long synthesis cycle. The resulting product has the advantages of low spray drying energy consumption, high purity and excellent fastness.

[0006] The technical solution provided by this invention is as follows: A process for preparing a reddish-brown reactive dye includes the following steps: 1) Add ice and water to 2-naphthylamine-4,6,8-trisulfonic acid, stir and slurry, add hydrochloric acid, and add sodium nitrite solution dropwise to obtain diazo solution in one diazo reaction; 2) Add 1-naphthylamine-7-sulfonic acid to diazo solution of 2-naphthylamine-4,6,8-trisulfonic acid and couple to obtain a mono-polymer. 3) Sodium nitrite is added to a certain material and then dropped into a mixture of hydrochloric acid and ice water. A secondary diazo reaction is then carried out to obtain a certain diazo solution. 4) Potassium carbonate is first added to m-toluidine, and then a diazonium solution is added to the mixture to produce a diazonium product through a coupling reaction. 5) Heat the dichromatic material and adjust the pH with hydrochloric acid, then use sodium and potassium salts for salting out, and filter the precipitated material by pressure to obtain a color base filter cake; 6) Add ice and water to cyanuric chloride, then add 2,5-disulfonic acid aniline and slurry, then condense in one step to obtain a condensed material; 7) Add the color base filter cake obtained in step 5) to the first condensed material, and perform a second condensation to obtain the second condensed material. Filter to obtain the reddish-brown reactive dye slurry.

[0007] The structural formula is as follows: .

[0008] In step 1) of this invention, after 2-naphthylamine-4,6,8-trisulfonic acid is pulped, the diazo reaction is completed using a conventional diazo method. Considering that 2-naphthylamine-4,6,8-trisulfonic acid itself has a high acid value, the amount of hydrochloric acid added can be reduced.

[0009] Preferably, in step 1), the molar ratio of 2-naphthylamine-4,6,8-trisulfonic acid, hydrochloric acid, and sodium nitrite is 1.0:0~0.5:0.98~1.05.

[0010] Preferably, the reaction temperature in step 1) is 3~8℃ and the reaction time is 1~3h.

[0011] In step 1), the main reaction process of primary diazotization is as follows: .

[0012] In step 2) of this invention, the primary coupling of diazonium salt and 1-naphthylamine-7-sulfonic acid is relatively easy to react and can be carried out under weakly alkaline conditions. Baking soda is used to adjust the pH during the reaction process.

[0013] Preferably, in step 2), after adding 1-naphthylamine-7-sulfonic acid, the reaction pH is maintained at 5.5~6.0.

[0014] Further optimization involves a reaction temperature of 5-10℃ and a reaction time of 3-6 hours.

[0015] In step 2), the main reaction process of a single coupling is as follows: .

[0016] In step 3) of this invention, the diazo reaction is completed by adding sodium nitrite to a liquid and then adding it dropwise to an acid solution.

[0017] Preferably, in step 3), the molar amount of hydrochloric acid is 4 to 5 times that of 2-naphthylamine-4,6,8-trisulfonic acid in step 2), and the molar amount of sodium nitrite is 0.95 to 1.03 times that of 2-naphthylamine-4,6,8-trisulfonic acid in step 2).

[0018] Preferably, the dripping time in step 3) is 0.5~1h.

[0019] Further optimization involves a reaction temperature of 6-10℃ and a reaction time of 1-3 hours.

[0020] The main reaction process of secondary diazotization in step 3) is as follows: .

[0021] In step 4) of this invention, in order to activate the activity of the para-amino position of m-toluidine and allow the material to undergo a full alkaline coupling reaction, the reaction pH value should be controlled at a high level. Therefore, potassium carbonate, an alkaline agent, is added to m-toluidine in advance, which also has a certain alkaline dissolution effect.

[0022] Preferably, the molar amount of potassium carbonate used in step 4) is 2 to 3 times that of m-toluidine.

[0023] Preferably, in step 4), 90% of the diazonium solution is added within 5 minutes.

[0024] Further optimization involves adding the remaining 10% dropwise over 10-20 minutes, while maintaining the reaction pH at 7.8-8.3 using a 15% potassium carbonate solution.

[0025] Preferably, the reaction temperature in step 4) is 8~12℃ and the reaction time is 3~6h.

[0026] The main reaction process of the secondary coupling in step 4) is as follows: .

[0027] In the process of synthesizing similar dyes, multiple azo processes are required. However, the azo reaction produces many byproducts, resulting in low product purity. Therefore, traditional technologies often use raw pulp salting out or membrane filtration to purify the dyes. However, this involves large investments and losses, as well as a large amount of wastewater.

[0028] In step 5) of this invention, the di-pair material is purified by salting out to obtain the chromophore, which then participates in the subsequent condensation reaction. This improves the final purity of the dye, reduces losses to a certain extent, increases the relative yield, and reduces the generation of some wastewater.

[0029] Preferably, in step 5), the pH of the di-coated material is adjusted with hydrochloric acid first, and then stirred at low speed.

[0030] Further optimization involves adjusting the pH of the hydrochloric acid to 5.0-5.5 and controlling the stirring speed to 60-100 rpm.

[0031] Further optimization involves first maintaining the temperature at 40-45°C, then adding sodium chloride and holding for 10-30 minutes, followed by maintaining the temperature at 45-50°C, then adding potassium chloride and holding for 60-90 minutes before pressure filtration. The amount of sodium chloride used is 8-12% of the mass of the di-aluminum material, and the amount of potassium chloride used is 2-5% of the mass of the di-aluminum material.

[0032] In step 6) of this invention, cyanuric chloride is easily hydrolyzed, and the reaction process is controlled at a low pH. At the same time, in order to save production time, cyanuric chloride and 2,5-disulfonic acid aniline are mixed and pulped.

[0033] Preferably, the start time of step 6) pulping is the same as the end time of step 4), and the pulping time is 1~2 hours.

[0034] Preferably, in step 6), potassium bicarbonate is used to maintain the reaction pH at 2.0~2.5, the reaction temperature at 4~8℃, and the reaction time at 1~3h.

[0035] The main condensation reaction process in step 6) is as follows: .

[0036] In step 7) of this invention, as the reaction proceeds, the dye structure becomes more complex, the molecular weight increases, and the steric hindrance becomes higher, requiring higher temperatures and pH levels to promote conversion efficiency. Simultaneously, a simple filtration step is added after the reaction to remove insoluble and sparingly soluble substances from the material.

[0037] Preferably, in step 7), a potassium carbonate solution (e.g., 15%) is used to maintain the reaction pH at 7.0-7.5.

[0038] Further preferred, in step 7), the reaction is first kept at 35~40℃ for 2~3 hours, and then kept at 45~50℃ for 0.5~1 hours.

[0039] Preferably, in step 7), the filtration method is a two-stage series filtration.

[0040] Further optimization involves using a 3µm PP filter element for the first stage of filtration and a 0.65µm nylon 66 filter element for the second stage. PP filter elements offer advantages such as high cost-effectiveness and long service life, while nylon 66 filter elements offer advantages such as high precision and high porosity.

[0041] Preferably, in step 7), the filtration time is 1 to 2 hours.

[0042] Preferably, in steps 1) to 7), the molar ratio of cyanuric chloride, 2,5-disulfonic acid aniline, m-toluidine, 1-naphthylamine-7-sulfonic acid and 2-naphthylamine-4,6,8-trisulfonic acid is 1:(0.96~1.06):(1.02~1.12):(1.05~1.15):(1.05~1.15).

[0043] The main reaction process of the secondary condensation in step 7) is as follows: .

[0044] Compared with similar products and technologies, the beneficial effects of this invention are as follows: (1) The dye paste has a high solid content, good fluidity, and little insoluble residue. The material is transported smoothly and without blockage during the spray drying process, resulting in low energy consumption. (2) The finished product has high purity and, compared with the traditional pulp refining process, the loss is low, the cost is controllable, and less wastewater is generated; (3) The dye has stable color, high fastness to soap washing and perspiration, and good solubility. Detailed Implementation

[0045] Example 1: Add 500 kg of water and 1000 kg of crushed ice to a 5 cubic meter reaction vessel, then add 634 kg of 2-naphthylamine-4,6,8-trisulfonic acid. Stir and slurry the mixture, then add 20 kg of 30% hydrochloric acid. Next, add sodium nitrite solution (prepared by mixing 82 kg of sodium nitrite with 185 kg of water). After the addition is complete, maintain the temperature at 3-8°C and react for 2 hours to obtain a primary diazo solution. Then add 270 kg of industrial-grade 1-naphthylamine-7-sulfonic acid. After the addition is complete, maintain the temperature at 5-10°C and use baking soda to maintain the pH of the reaction at 5.5-6.0. React for 4 hours to obtain a primary coupling solution. Finally, add 80 kg of sodium nitrite.

[0046] Add 500 kg of bottom water, 1000 kg of crushed ice, and 630 kg of 30% hydrochloric acid to a 10 cubic meter reaction vessel. Then, add the first coupling solution with added sodium nitrite dropwise over about 40 minutes. Keep the temperature at 6-10℃ and react for 2 hours to obtain a diazo solution.

[0047] Add a small amount of bottom water, 122 kg of m-toluidine, and 370 kg of potassium carbonate to a 15 cubic meter reaction vessel and stir. First, add 90% of the azo solution over 5 minutes, then slowly add the remaining 10% dropwise. During the dropwise addition, maintain the pH at 7.8-8.3 with a 15% potassium carbonate solution. After the addition is completed in about 15 minutes, continue to maintain the pH at 7.8-8.3 and keep the reaction at 8-12℃ for 4 hours. After the secondary coupling endpoint is reached, adjust the pH to 5.0-5.5 with hydrochloric acid, control the stirring speed at 80 rpm, calculate the mass, and keep the temperature at 40-45℃. First, add about 10% sodium chloride by mass, and after 20 minutes, keep the temperature at 45-50℃ and add about 5% potassium chloride by mass. After 70 minutes, start filtration and collect the filter cake after pressing.

[0048] Add 500 kg of water and 1000 kg of crushed ice to a 15 cubic meter reaction vessel, then add 200 kg of cyanuric chloride and 300 kg of 2,5-disulfonic acid aniline. After the secondary coupling endpoint is reached, start stirring and pulping for 1.5 hours, maintaining the temperature below 5°C to obtain a pulp. Then, use potassium bicarbonate to maintain the pH at 2.0-2.5 and keep the temperature at 4-8°C for 2 hours. After the pH of the first condensation material stabilizes, add the entire batch of color base filter cake, stir and heat, and add an appropriate amount of water to disperse the color base filter cake. First, raise the temperature to 35-40°C and react for 2.5 hours, then raise the temperature to 45-50°C and react for 1 hour. During the reaction, use a 15% potassium carbonate solution to maintain the pH at 7.0-7.5. After the secondary condensation endpoint is reached, the material undergoes secondary filtration for 1 hour to obtain the raw pulp.

[0049] After standardizing the original pulp, it was spray-dried to obtain a reddish-brown reactive dye powder.

[0050] Example 2: The difference from Example 1 is that the dosage of 2-naphthylamine-4,6,8-trisulfonic acid is 630 kg and the dosage of m-toluidine is 120 kg.

[0051] Example 3: The difference from Example 1 is that the dosage of cyanuric chloride is 205 kg and the dosage of 2,5-disulfonic acid aniline is 308 kg.

[0052] Comparative Example 1: Unlike Example 1, the material after the secondary coupling endpoint was not refined.

[0053] Comparative Example 2: Unlike Example 1, no secondary filtration was performed after the second condensation.

[0054] Comparative Example 3: Add 500 kg of water and 1000 kg of crushed ice to a 5 cubic meter reaction vessel, then add 635 kg of 2-naphthylamine-4,6,8-trisulfonic acid. Stir and slurry the mixture, then add 50 kg of 30% hydrochloric acid. Next, add sodium nitrite solution (prepared by mixing 82 kg of sodium nitrite with 185 kg of water) dropwise. After the addition is complete, maintain the temperature at 3-8°C and react for 2 hours to obtain a primary diazo solution. Then add 270 kg of industrial-grade 1-naphthylamine-7-sulfonic acid. After the addition is complete, maintain the temperature at 5-10°C and use baking soda to maintain the pH at 5.5-6.0. React for 4 hours to obtain a primary coupling solution. Finally, add 80 kg of sodium nitrite.

[0055] Add 500 kg of bottom water, 1000 kg of crushed ice, and 630 kg of 30% hydrochloric acid to a 10 cubic meter reaction vessel. Then, add the primary coupling solution with added sodium nitrite dropwise over approximately 40 minutes. Maintain the temperature at 6-10°C for 2 hours to obtain a primary diazo solution. Next, add 125 kg of m-toluidine and maintain the pH at 7.5-8.5 with 10% liquid alkali. Maintain the temperature at 8-12°C for 4 hours to obtain a secondary coupling solution.

[0056] Add 500 kg of water and 1000 kg of crushed ice to a 15 cubic meter reaction vessel. Then add 220 kg of cyanuric chloride and 335 kg of 2,5-disulfonic acid aniline. After the secondary coupling endpoint is reached, start stirring and slurrying for 1.5 hours, keeping the temperature below 5°C to obtain a slurry. Then, use potassium bicarbonate to maintain the pH at 2.0-2.5 and keep the temperature at 4-8°C for 2 hours. After the pH of the primary material stabilizes, add the secondary coupling solution, stir and raise the temperature to 40°C, and use a 15% potassium carbonate solution to maintain the pH at 7.0-7.5, keeping the temperature at 40-45°C for 2-3 hours.

[0057] After the second condensation endpoint is reached, the mass is calculated, and the temperature is maintained at 40~45℃. Sodium chloride of about 15% by mass is added. After stirring for 2 hours after the addition, the filter is pressed. After pressing, the filter cake is collected, and the filter cake is pulped and dissolved to obtain the raw pulp.

[0058] Comparative Example 4: The sample synthesized according to Example 4 of the specific embodiments in the Chinese Patent Specification No. 200910082345.5 was filtered by plate and frame filter press, but not by nanofiltration system.

[0059] The samples prepared in Examples 1-3 and Comparative Examples 1-4 were compared. Table 1 shows the data on sample color, purity, relative yield, solid content, insoluble matter and wastewater volume (color and relative yield are based on Example 1); Table 2 shows the test data on the standard sample partial fastness and solubility.

[0060] Table 1. Test data on color, purity, relative yield, solids content, insoluble matter, and wastewater content of the samples obtained in Examples 1-3 and Comparative Examples 1-4.

[0061] As can be seen from the data in Table 1, the differences between Examples 1-3 are very small, indicating that the process of the present invention is stable and minor adjustments have little impact on the overall quality of the dye. Secondly, compared with Examples 1-3, Comparative Example 1, while ensuring a higher yield of raw pulp, sacrifices the overall quality of the dye, affecting sales volume and price, which also reflects the necessity of the refining process of the present invention. Compared with Examples 1-3, Comparative Example 2 has a very high insoluble residue, close to 1%, indicating that the elimination of the secondary filtration process has a significant impact on insoluble residue. Although the purity of Comparative Example 3 is slightly higher than that of Examples 1-3, the yield is very low, decreasing by about 10% compared to Comparative Example 1 and by about 5% compared to Examples 1-3. The wastewater volume is also twice that of Examples 1-3, indicating that the process... While conventional processes for synthesizing raw pulp followed by refining can indeed improve dye quality, the improvement is limited compared to this invention. Furthermore, it reduces yield and increases wastewater treatment costs, making it less than optimal. Comparative Example 4, after coarse filtration using a plate and frame filter press, removes insoluble matter to some extent, but the filtration precision is insufficient. Overall, compared to Examples 1-3, although the yield is slightly higher, purity, color, and insoluble residue are all inadequate. Comparative Example 4 further utilizes a nano-membrane filtration system to remove inorganic salts and a small amount of byproducts. As is known in the industry, membrane filtration typically requires at least 2-3 times the volume of water for circulation to achieve a filtration effect, and it does not substantially improve product purity. It also discharges a large amount of filtrate, resulting in wastewater generation far exceeding that of the embodiments of this invention.

[0062] Table 2. Test data on the firmness and solubility of standardized sample portions.

[0063] As can be seen from the data in Table 2, the solubility of Examples 1-3 can reach 250 g / L, while that of Comparative Example 4 is only 150 g / L, indicating that the solubility of the dye of the present invention is significantly better than that of similar products. In addition, the partial fastness of Examples 1-3 is also slightly better than that of Comparative Examples 1-4, indicating that the dye of the present invention also has certain advantages in practical applications.

Claims

1. A preparation process for a reddish-brown reactive dye, characterized in that, Includes the following steps: 1) Add ice and water to 2-naphthylamine-4,6,8-trisulfonic acid, stir and slurry, add hydrochloric acid, and add sodium nitrite solution dropwise to obtain diazo solution in one diazo reaction; 2) Add 1-naphthylamine-7-sulfonic acid to diazo solution of 2-naphthylamine-4,6,8-trisulfonic acid and couple to obtain a mono-polymer. 3) Sodium nitrite is added to a certain material and then dropped into a mixture of hydrochloric acid and ice water. A secondary diazo reaction is then carried out to obtain a certain diazo solution. 4) Potassium carbonate is first added to m-toluidine, and then a diazonium solution is added to the mixture to produce a diazonium product through a coupling reaction. 5) Heat the dichromatic material and adjust the pH with hydrochloric acid, then use sodium and potassium salts for salting out, and filter the precipitated material by pressure to obtain a color base filter cake; 6) Add ice and water to cyanuric chloride, then add 2,5-disulfonic acid aniline and slurry, then condense in one step to obtain a condensed material; 7) Add the color base filter cake obtained in step 5) to the first condensed material, and perform a second condensation to obtain the second condensed material. Filter to obtain the reddish-brown reactive dye slurry.

2. The preparation process of the reddish-brown reactive dye according to claim 1, characterized in that, In step 1), the reaction temperature is 3~8℃, the reaction time is 1~3h, and the molar ratio of 2-naphthylamine-4,6,8-trisulfonic acid, hydrochloric acid and sodium nitrite is 1.0:0~0.5:0.98~1.

05.

3. The preparation process of the reddish-brown reactive dye according to claim 1, characterized in that, In step 2), sodium bicarbonate is used to maintain the reaction pH at 5.5-6.0, the reaction temperature at 5-10℃, and the reaction time at 3-6 hours.

4. The preparation process of the reddish-brown reactive dye according to claim 1, characterized in that, In step 3), the molar amount of hydrochloric acid is 4 to 5 times that of 2-naphthylamine-4,6,8-trisulfonic acid in step 2), the molar amount of sodium nitrite is 0.95 to 1.03 times that of 2-naphthylamine-4,6,8-trisulfonic acid in step 2), the dropping time is 0.5 to 1 h, the reaction temperature is 6 to 10 °C, and the reaction time is 1 to 3 h.

5. The preparation process of the reddish-brown reactive dye according to claim 1, characterized in that, In step 4), the amount of potassium carbonate used is 2 to 3 times that of m-toluidine. Then, 90% of the azo solution is added within 5 minutes, and the remaining 10% is added dropwise over 10 to 20 minutes. During this period, the pH of the reaction is maintained at 7.8 to 8.3 with 15% potassium carbonate solution, the reaction temperature is 8 to 12°C, and the reaction time is 3 to 6 hours.

6. The preparation process of the reddish-brown reactive dye according to claim 1, characterized in that, In step 5), the hydrochloric acid is adjusted to pH 5.0-5.5, and then the stirring speed is controlled at 60-100 rpm. Sodium chloride is added while maintaining the temperature at 40-45℃ for 10-30 minutes, and potassium chloride is added while maintaining the temperature at 45-50℃ for 60-90 minutes before pressure filtration. The amount of sodium chloride used is 8-12% of the mass of the diammonium ether material, and the amount of potassium chloride used is 2-5% of the mass of the diammonium ether material.

7. The preparation process of the reddish-brown reactive dye according to claim 1, characterized in that, In step 6), the pulping start time is the same as the end time of step 4), the pulping time is 1~2h, potassium bicarbonate is used to maintain the reaction pH at 2.0~2.5, the reaction temperature is 4~8℃, and the reaction time is 1~3h.

8. The preparation process of the reddish-brown reactive dye according to claim 1, characterized in that, In step 7), potassium carbonate solution is used to maintain the reaction pH at 7.0~7.

5. The reaction is first kept at 35~40℃ for 2~3 hours, and then kept at 45~50℃ for 0.5~1 hours.

9. The preparation process of the reddish-brown reactive dye according to claim 1, characterized in that, In step 7), the filtration method is a two-stage series filtration. The first stage uses a 3um PP filter element, and the second stage uses a 0.65um nylon 66 filter element. The filtration time is 1~2 hours.

10. The preparation process of the reddish-brown reactive dye according to any one of claims 1-9, characterized in that, In steps 1) to 7), the molar ratio of cyanuric chloride, 2,5-disulfonic acid aniline, m-toluidine, 1-naphthylamine-7-sulfonic acid and 2-naphthylamine-4,6,8-trisulfonic acid is 1:(0.96~1.06):(1.02~1.12):(1.05~1.15):(1.05~1.15).

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