A preparation process of gray-black reactive dye

Abstract

The present invention discloses a preparation process for a gray-black reactive dye: gamma-acid refining, followed by primary coupling with 2,5-dimethoxy para-ester diazonium salt, diazotization of the secondary coupling liquid, and secondary coupling with 1-(4-sulfonylphenyl)-3-carboxyl-5-pyrazolone to obtain a chromogen. After the chromogen complexation reaction, the temperature is lowered and filtered to obtain a dye stock. The preparation process provided by the present invention utilizes raw material refining technology and improves the reaction conversion effect of each unit by optimizing the reaction route, adjusting the diazotization process, and other methods, thereby enhancing the dye purity. The resulting product has the advantages of pure color, high light fastness, and low content of extractable heavy metal copper remaining on the fabric.

Description

Technical Field

[0001] The invention belongs to the field of reactive dye preparation, and particularly relates to a preparation process of a gray-black reactive dye. Background Art

[0002] Metal complex dyes are typically formed by complexing existing dyes with metal ions (such as copper, cobalt, chromium, and nickel) to form a type of dye containing coordinated metal atoms within the molecule. These metal complex dyes generally exhibit higher light and wash fastness than conventional dyes. They are common in acid, reactive, and disperse dyes, and have a deep color spectrum, often ranging from purple-red, gray-black, and dark blue. A small number of dyes can also exhibit vibrant colors.

[0003] The present invention relates to a reactive dye CIReactive Black 31, which is a metal complex disazo dye, and its Chinese alias is Reactive Black 31, Reactive Black KN-RL, and its molecular formula is C 29 H 18 CuN6Na4O 18 S4, with a molecular weight of 1022.25, is a gray-toned black reactive dye suitable for dyeing cotton and viscose fibers, direct printing or discharge printing on cotton. It can be used for matching and toning certain metal complex dyes, and can also be processed into digital ink for inkjet printing.

[0004] Its structural formula is as follows:

[0005]

[0006] Dyes & Coloring, February 2008, Issue 1, Pages 15-16, disclosed a method for synthesizing Reactive Black KN-RL. Specifically, gamma acid is diazotized at low temperature and then coupled with 1-(4-sulfonatophenyl)-3-carboxy-5-pyrazolone. The diazotized 2,5-dimethoxy para-ester is then coupled with the monoazo dye. After coupling, sodium acetate and copper sulfate are added sequentially at room temperature. Once dissolved, the pH is adjusted to 5.0-6.0 with hydrochloric acid or sodium hydroxide. The mixture is stirred for 20 minutes. Once the pH stabilizes, the temperature is raised to 102-104°C and maintained for 10 hours. The dye stock is obtained when red spots on the thin layer of colored paper disappear. The synthesis process for Reactive Black RL dye, disclosed in Guangzhou Chemical Industry, Volume 40, Issue 21, November 2012, Pages 95-97, follows a similar synthetic route. Although this synthetic route abandons the salting-out step and simplifies the process compared to the previous one, the process control is rough, the unit reaction conversion rate is low, the complexation reaction temperature is too high, and the active groups of the dye are easily destroyed at high temperature. The dye produced still has problems such as low purity, low fixation rate, and reddish color. In addition, the color of the cloth is uneven during the dyeing process, the levelness is poor, and auxiliary agents are required to assist in coloring. Moreover, the cloth surface turns red after dyeing and cannot show a pure gray luster. The quality is still somewhat lower than that of similar foreign products and cannot meet the needs of the high-end market. Summary of the Invention

[0007] The present invention aims to provide a process for preparing a gray-black reactive dye, wherein the prepared product has the advantages of high purity, good color fixation rate, excellent light fastness and low content of extractable heavy metal copper remaining on the cloth surface.

[0008] The technical solution provided by the present invention is:

[0009] A preparation process of a gray-black reactive dye comprises the following steps:

[0010] 1) ice and water were added to 2,5-dimethoxy para-ester to make a slurry, hydrochloric acid was added, and sodium nitrite solution was added dropwise to carry out diazotization reaction to obtain a primary diazonium salt;

[0011] 2) adding gamma acid to the bottom water, stirring and heating, adjusting alkali to dissolve and filter once, collecting the filtrate and cooling, and then filtering twice to obtain a refined gamma acid filter cake;

[0012] 3) adding the refined gamma acid filter cake obtained in step 2) to the primary diazonium salt obtained in step 1) to carry out a coupling reaction, and obtaining a coupling liquid after the reaction is complete;

[0013] 4) adding sodium nitrite to the mixed solution obtained in step 3) to dissolve it, and then adding it dropwise to the mixed acid to obtain a secondary diazonium salt after the reaction is complete;

[0014] 5) adding 1-(4-sulfonylphenyl)-3-carboxyl-5-pyrazolone powder to the secondary diazo solution obtained in step 4) to carry out a secondary coupling reaction, and obtaining a chromophore after the reaction is complete;

[0015] 6) Adding copper chloride powder to the color base obtained in step 5) to carry out a complex reaction. After the reaction reaches the end point, the temperature is lowered and filtered, and the filtrate is the dye stock.

[0016] The preparation process provided by the present invention utilizes raw material refining technology and, through methods such as optimizing the reaction route and adjusting the diazotization process, improves the reaction conversion efficiency of each unit, thereby enhancing the purity of the dye. The resulting dyed fabric has advantages such as pure color, high light fastness, and low copper ion residue. It also solves problems such as reddish color and easy destruction of active groups.

[0017] The structural formula is as follows:

[0018]

[0019] In the step 1), the diazo reaction process is as follows:

[0020]

[0021] In step 1) of the present invention, the 2,5-dimethoxy para-ester should be fully beaten before the diazo reaction to improve the reaction conversion effect. The diazo reaction should be carried out at a low temperature. Too high a temperature will cause the diazonium salt to decompose.

[0022] Preferably, in step 1), the beating time of 2,5-dimethoxy para-ester is 1.5 to 2 hours, the beating and diazo reaction temperature is controlled at 0 to 5° C., and the reaction time is 1 to 1.5 hours.

[0023] Preferably, in step 1), the molar ratio of hydrochloric acid, sodium nitrite and 2,5-dimethoxy para-ester is (1.05-1.2):(1-1.1):1.

[0024] The gamma acid used in step 2) of the present invention is a conventional industrial-grade product on the market and contains various impurities, of which insoluble matter is generally about 0.5%, bromophenol (2-naphthylamine-6-sulfonic acid) is about 1%, and it also contains amino G acid, DOG acid (4,6-dihydroxy-2-naphthalenesulfonic acid), etc. The traditional process directly uses it as a raw material, which easily leads to the generation of many by-products, ultimately affecting the color and purity of the dye. The present invention adds a simple and convenient process to purify it to achieve the purification effect. First, the gamma acid is dissolved in an alkali solution at high temperature, and the insoluble matter is removed by a first filtration to obtain a filtrate. Then, taking advantage of the principle that gamma acid is easily precipitated at low temperature, the filtrate is cooled and a refined gamma acid filter cake is obtained by a second filtration, and the quality can be greatly improved.

[0025] Preferably, in step 2), the temperature during the dissolution of the gamma acid and the primary filtration should be kept at 55-60°C.

[0026] Preferably, in step 2), liquid caustic soda is used to adjust the pH value to 7.0-7.5 to obtain a clear solution, and the solid content of the clear solution should be controlled at 25-30%. More preferably, 30% liquid caustic soda is used.

[0027] Preferably, in step 2), the primary filtrate should be cooled to 10-12° C. before secondary filtration.

[0028] In the step 3), the coupling reaction process is as follows:

[0029]

[0030] In step 3) of the present invention, the coupling reaction needs to be carried out under alkaline conditions. Since it is the first coupling reaction, the steric hindrance is small and the reaction is easier to proceed. Therefore, the refined gamma acid needs to be added to the reaction system as soon as possible, and a milder baking soda is selected as the alkaline agent.

[0031] Preferably, in step 3), the refined gamma acid is quickly added to the diazonium salt, while baking soda is used to adjust and maintain the pH value at 6.3 to 6.5, and the temperature is controlled at 5 to 10°C.

[0032] More preferably, the reaction time is 3 to 4 hours, and the molar ratio of baking soda to gamma acid is (0.8 to 1.1):1.

[0033] The secondary diazo reaction process in step 4) is as follows:

[0034]

[0035] In step 4 of the present invention, as the reaction proceeds, the product structure becomes increasingly complex. Conventional means are now employed to carry out a secondary diazo reaction, and the reaction is difficult to carry out, resulting in poor conversion. By trial and error, a trans-diazo reaction is performed by means of a trans-diazo reaction, i.e., sodium nitrite is added to a mono-even material, and after dissolving, the mono-even material is added dropwise to a low-temperature acidic system. During the addition process, the material contacts an acid solution and is rapidly converted into a diazonium salt. Unconverted mono-even material and the converted diazonium salt also do not interfere with each other, thereby improving conversion efficiency and preventing side reactions from occurring.

[0036] In addition, in step 4) of the present invention, unlike the traditional process of simply using hydrochloric acid to perform the diazo reaction, phosphoric acid and hydrochloric acid are selected to form a mixed acid to provide an acidic environment for the reaction. Phosphoric acid, as a medium-strong acid, has almost no oxidizing property and does not interfere with the test paper detection of the diazo reaction and the reaction process. It can replace part of the hydrochloric acid to fill the acid value and generate phosphate in the subsequent reaction. Phosphate has pH buffering capacity and can play the role of an acid binding agent during the complex reaction. No additional acid binding agent needs to be added during the complex reaction. At the same time, after the complex reaction is completed, it combines with free copper ions to generate copper phosphate. The principle of extremely poor water solubility of copper phosphate at room temperature is utilized. After the complex reaction is completed, the temperature is lowered to precipitate it, and then adsorption and filtration are performed to achieve the purpose of removing residual copper ions.

[0037] Preferably, in step 4), ice is added to control the reaction temperature to 0-5°C; the mixed acid is a mixture of hydrochloric acid and phosphoric acid, and the molar ratio of hydrochloric acid, phosphoric acid, sodium nitrite and gamma acid is (1-1.5):(0.5-1):(0.95-1.05):1.

[0038] Preferably, in step 4), the time for dropwise addition to the mixed acid should be controlled within 20 to 30 minutes, and the reaction time should be controlled within 1.5 to 2 hours.

[0039] The secondary coupling reaction process in step 5) is as follows:

[0040]

[0041] In step 5) of the present invention, the secondary coupling reaction is more difficult than the primary coupling reaction. If baking soda is continued to be used to adjust the base, the coupling rate will be too slow, the reaction time will be too long, and the diazonium salt will self-couple. Therefore, the reaction process needs to be carried out under stronger alkaline conditions; in addition, while ensuring that the diazonium salt does not decompose, the temperature is appropriately increased to improve the coupling conversion efficiency.

[0042] Preferably, in step 5), 1-(4-sulfonylphenyl)-3-carboxyl-5-pyrazolone powder is directly added, and the pH value is adjusted and maintained at 6.5 to 7.0 with 20% pure alkali solution.

[0043] Preferably, the reaction temperature in step 5) is controlled at 10-15° C., and the reaction time is controlled at 6-7 h.

[0044] The complexation reaction process in step 6) is as follows:

[0045]

[0046] In step 6 of the present invention, the traditional process complexation pH value is between 5.0 and 6.0. Although the reaction is relatively mild at this pH value and the color base is not easily hydrolyzed, the reaction temperature needs to reach more than 100 ° C to shorten the reaction time. At the same time, the color base is difficult to be completely converted into a dye complex. The residual color base can cause the dye color to be reddish. After dyeing or printing, the fabric is reddish and the color is not pure. Compared with the traditional process, the present invention can avoid the risk of traditional color base high temperature complexation while ensuring that the color base is thoroughly converted by increasing the complexation pH and reducing the reaction temperature, and reduce the impact of various by-products on dye fixation rate and color fastness. In addition, the complexation reaction process no longer requires the additional addition of an acid binding agent. Only normal alkali adjustment is required to ensure that the reaction proceeds smoothly, a suitable developing agent is deployed, and endpoint detection is completed using TLC thin plate chromatography. The pH is then adjusted with phosphoric acid to further react free copper ions, filtered and removed, and the dye stock is obtained.

[0047] Preferably, in step 6), copper chloride powder is first added, and after the powder is completely dissolved, the temperature is raised and kept at 85-90° C. During the reaction, 15% liquid caustic soda is used to adjust the pH value to 7.5-7.8.

[0048] Preferably, the reaction time of the complexation reaction in step 6) is controlled to be 8 to 10 hours, the endpoint detection method is TLC thin plate chromatography, and the developing solvent is a mixture of n-butanol, ethyl acetate, pyridine and water in a volume ratio of 4:2:2:1.

[0049] More preferably, the reaction endpoint is when there are no purple or dark red spots in the TCL thin plate chromatography.

[0050] Preferably, after the reaction reaches the end point in step 6), the temperature is lowered to 30-35° C., and the pH value is adjusted with phosphoric acid. Celite is added, stirred for 1 hour, filtered, and the filtrate is collected.

[0051] More preferably, the amount of diatomaceous earth added is 0.5-1% of the volume of the slurry.

[0052] Preferably, in steps 1) to 6), the molar ratio of 2,5-dimethoxy para-ester, gamma acid, 1-(4-sulfonic acid phenyl)-3-carboxy-5-pyrazolone and copper chloride is (0.98-1.05):1:(0.95-1):(1.05-1.2).

[0053] Compared with the traditional process, the present invention prepares gray-black reactive dyes by optimizing the reaction route, refining the reaction raw materials and adjusting the reaction parameters. The advantages of the preparation process provided are:

[0054] (1) The production equipment requirements are low, the reaction process is at normal pressure and low temperature, and the operator safety is high;

[0055] (2) The process is stable, the unit reaction conversion effect is good, the purity of the raw pulp is high, and it is conducive to long-term storage;

[0056] (3) The dye has good color fixation rate and high fastness, especially light fastness, which can reach level 7 or above;

[0057] (4) Good reproducibility, no defects on the fabric after printing and dyeing, pure color, low content of extractable heavy metal copper remaining on the fabric, in line with Oeko-Tex standards, and meeting environmental protection requirements. DETAILED DESCRIPTION

[0058] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0059] Example 1

[0060] Add 800 kg of bottom water to a 5-cubic-meter dissolving pot, add 250 kg of gamma acid, stir and heat, adjust the pH value to 7.0-7.5 with 30% liquid alkali, keep warm at 55-60°C, ensure that the solution is clear, filter once, collect the filtrate, then cool the filtrate to 10-12°C, and then filter twice, collect the filter cake to obtain refined gamma acid.

[0061] Add 500kg of bottom water and 1000kg of crushed ice to a 10-cubic-meter reaction pot, then add 350kg of 2,5-dimethoxypara-ester, stir and slurry for 1.5 hours, add 130kg of 30% industrial hydrochloric acid, continue stirring for 10 minutes, add 250kg of 30% sodium nitrite solution dropwise, keep warm at 0-5°C, continue to keep warm and react for 1.5 hours after the addition is complete, and use aminosulfonic acid to eliminate excess sodium nitrite to obtain 2,5-dimethoxypara-ester diazonium salt. Quickly add refined gamma acid to 2,5-dimethoxypara-ester diazonium salt, while adjusting and maintaining the pH value at 6.3-6.5 with baking soda, control the temperature at 5-10°C, react for 4 hours to the primary coupling endpoint to obtain a coupling liquid, then add 76kg of sodium nitrite solid, stir and set aside.

[0062] Add 500 kg of bottom water and 1500 kg of crushed ice to a 15-cubic-meter reactor and stir. Then, add 150 kg of 30% industrial hydrochloric acid and 75 kg of 85% industrial phosphoric acid. Add the primary coupling material from the 10-cubic-meter reactor quickly, then slowly, to this reactor over 20-30 minutes. Insulate at 0-5°C and react for 2 hours. Remove excess sodium nitrite with aminosulfonic acid to obtain the secondary diazonium salt. Directly add 280 kg of 1-(4-sulfophenyl)-3-carboxy-5-pyrazolone powder and adjust and maintain the pH at 6.5-7.0 with 20% pure alkali solution. Once the pH stabilizes, insulate at 10-15°C and react for 6-7 hours to the secondary coupling endpoint.

[0063] Continue to add 140kg of copper chloride, stir for 30 minutes to completely dissolve, then start heating. After the temperature reaches 85-90℃, continue to keep the temperature to react. During the entire reaction period, use 15% liquid alkali to maintain the pH value at 7.5-7.8. React for 8-10 hours. Use TLC thin plate chromatography to detect whether there are purple or dark red spots on the plate. The reaction ends when there are no spots. If there are spots, the reaction time must be extended until the spots disappear. After the reaction reaches the end point, cool to 30-35℃ and adjust the pH value to 6-6.5 with a small amount of phosphoric acid. Then add 50kg of diatomaceous earth, stir for 1 hour, filter, and collect the filtrate to obtain the dye slurry.

[0064] The raw pulp was standardized and spray-dried to obtain reactive black KN-RL dye dry powder.

[0065] Example 2

[0066] The difference from Example 1 is that the dosage of gamma acid is 245 kg, and the dosage of 2,5-dimethoxy para-ester is 345 kg.

[0067] Example 3

[0068] The difference from Example 1 is that during the secondary diazo reaction, 500 kg of bottom water and 1500 kg of crushed ice were added to the 15-cubic-meter reaction pot, stirred, and then 140 kg of 30% industrial hydrochloric acid and 80 kg of 85% industrial phosphoric acid were added.

[0069] Comparative Example 1

[0070] The difference from Example 1 is that the secondary diazo reaction is a cis-diazo reaction, that is, after the completion of the primary coupling, the first coupling liquid is transferred to a 15-cubic-meter reaction pot, and then 150 kg of 30% industrial hydrochloric acid, 100 kg of 85% industrial phosphoric acid, and 1200 kg of ice are added, and then 260 kg of a dissolved 30% sodium nitrite solution is added dropwise, and the addition time is controlled to 20 to 30 min. After the addition, the temperature is kept at 0 to 5 ° C, the reaction is carried out for 2 h, and the excess sodium nitrite is eliminated with sulfamic acid to obtain a secondary diazonium salt.

[0071] Comparative Example 2

[0072] The difference from Example 1 is that after the complexation reaction reaches the end point, the pH adjustment and adsorption filtration steps are removed, and the material is directly used as the raw pulp for standardization treatment.

[0073] Comparative Example 3

[0074] Add 500kg of bottom water and 1000kg of crushed ice to a 15-cubic-meter reaction pot, then add 250kg of gamma acid, stir and slurry for 1.5 hours, add 140kg of 30% industrial hydrochloric acid, continue stirring for 10 minutes, add 250kg of 30% sodium nitrite solution dropwise, and keep it at 0-5°C. After the addition is complete, continue to keep it at this temperature for 1.5 hours. Use aminosulfonic acid to eliminate the excess sodium nitrite to obtain gamma acid diazonium salt. Add 275kg of 1-(4-sulfonylphenyl)-3-carboxy-5-pyrazolone powder, and adjust and maintain the pH at 5.5-6.0 with baking soda. After the pH stabilizes, keep it at 5-10°C and react for 4-5 hours to the primary coupling endpoint to obtain a coupled material.

[0075] Add 500 kg of bottom water and 1200 kg of crushed ice to a 5-cubic-meter reaction pot, then add 340 kg of 2,5-dimethoxy para-ester, stir and beat for 1.5 hours, add 130 kg of 30% industrial hydrochloric acid, continue stirring for 10 minutes, add 250 kg of 30% sodium nitrite solution dropwise, keep warm at 0-5°C, continue to keep warm and react for 1.5 hours after the addition is completed, and use aminosulfonic acid to eliminate excess sodium nitrite to obtain 2,5-dimethoxy para-ester diazonium salt.

[0076] Add 2,5-dimethoxy para-ester diazonium salt to the primary coupling material, continue to adjust and maintain the pH at 6.5-7.0 with baking soda, keep warm at 10-15°C, and react for 7-8 hours until the secondary coupling endpoint is reached. Then, add 100kg of sodium acetate and 155kg of copper sulfate in sequence, stir for 30 minutes to dissolve, adjust the pH to 5.0-6.0 with a small amount of hydrochloric acid, continue stirring for 20 minutes, and after the pH stabilizes, raise the temperature to 102-104°C and keep warm for 10 hours. The end point is when the red spots on the thin layer of colored paper disappear, and the dye pulp is obtained.

[0077] The raw pulp was standardized and spray-dried to obtain reactive black KN-RL dye dry powder.

[0078] The black reactive dye products prepared in Examples 1-3 were compared with Comparative Example 1, Comparative Example 2 and Comparative Example 3 synthesized according to a traditional process, as shown in Tables 1 and 2.

[0079] Table 1 Data on dye fixation rate, purity, solubility and insoluble matter mass fraction of Examples 1-3 and Comparative Examples 1-3

[0080] product Fixation rate / % purity / % Solubility / (g / L) Insoluble matter mass fraction / % Example 1 70 91.13 250 Not detected Example 2 70 90.88 250 Not detected Example 3 70 91.22 250 Not detected Comparative Example 1 65 86.42 200 0.1 Comparative Example 2 68 88.21 240 0.3 Comparative Example 3 65 85.37 180 0.7

[0081] Table 2 Test data of color, light fastness and extractable heavy metal copper residue of fabric samples after dye application in Examples 1-3 and Comparative Examples 1-3

[0082] fabric swatches Color Light Light fastness (xenon arc) / grade Extractable heavy metal copper residue / (mg / kg) Example 1 Slightly green 7 5 Example 2 Microgreens 7 4 Example 3 Slightly bright green 7 5 Comparative Example 1 Slightly reddish 5～6 10 Comparative Example 2 Slightly bright green 7 325 Comparative Example 3 Darker red 5～6 240

[0083] Table 1 shows the data for dye fixation rate, purity, solubility, and insoluble matter mass fraction. Table 2 shows the test data for fabric color shade, light fastness, and extractable heavy metal copper residue after dye application (the color shade is based on the imported reactive black KN-RL on the market). As can be seen from Tables 1 and 2, the various data of the embodiment are stable and significantly better than those of Comparative Example 3. Moreover, the small adjustment of the raw material dosage in Examples 1-3 has little effect on the various test parameters, resulting in high reproducibility and stable and reliable technology. Among the comparative examples, Comparative Example 1 adjusts the diazo reaction process relative to the present invention, resulting in poor conversion effect, a significant impact on the dye color shade, color fixation rate, and fastness, with the color shade becoming darker and the fastness decreasing; Comparative Example 2 adjusts the subsequent complexation process, which has less effect on the color shade and fastness, but results in the insoluble matter in the original pulp being unable to be removed, resulting in a high level of dye insoluble matter residue, and the extractable heavy metal copper residue in the fabric sample test is too high, failing to meet the index requirements.

[0084] Among them, the color fixation rate and solubility in Table 1 and the light fastness in Table 2 are all rounded to integers according to industry practice.

[0085] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A process for preparing a gray-black reactive dye, characterized in that: The steps include: 1) ice and water were added to 2,5-dimethoxy para-ester to make a slurry, hydrochloric acid was added, and sodium nitrite solution was added dropwise to carry out diazotization reaction to obtain a primary diazonium salt; 2) adding gamma acid to the bottom water, stirring and heating, adjusting alkali to dissolve and filter once, collecting the filtrate and cooling, and then filtering twice to obtain a refined gamma acid filter cake; 3) adding the refined gamma acid filter cake obtained in step 2) to the primary diazonium salt obtained in step 1) to carry out a coupling reaction, and obtaining a coupling liquid after the reaction is complete; 4) adding sodium nitrite to the mixed solution obtained in step 3) to dissolve it, and then adding it dropwise to the mixed acid to obtain a secondary diazonium salt after the reaction is complete; wherein the mixed acid is a mixture of hydrochloric acid and phosphoric acid; 5) adding 1-(4-sulfonylphenyl)-3-carboxyl-5-pyrazolone powder to the secondary diazo solution obtained in step 4) to carry out a secondary coupling reaction, and obtaining a chromophore after the reaction is complete; 6) Adding copper chloride powder to the color base obtained in step 5) to carry out a complex reaction. After the reaction reaches the end point, the temperature is lowered and filtered, and the filtrate is the dye stock.

2. The preparation process of gray-black reactive dye according to claim 1, wherein In the step 1), the beating time of 2,5-dimethoxy para-ester is 1.5 to 2 hours, the beating and diazo reaction temperature is controlled at 0 to 5°C, and the reaction time is 1 to 1.5 hours; the molar ratio of hydrochloric acid, sodium nitrite and 2,5-dimethoxy para-ester is (1.05 to 1.2): (1 to 1.1):

1.

3. The preparation technology of gray-black reactive dye according to claim 1, wherein In the step 2), the temperature is raised to 55-60° C. with stirring, and the pH value is adjusted to 7.0-7.5 with liquid alkali to dissolve the solution.

4. The preparation process of gray-black reactive dye according to claim 1, wherein In the step 2), the primary filtrate is first cooled to 10-12° C. and then subjected to secondary filtration.

5. The preparation process of gray-black reactive dye according to claim 1, wherein In the step 3), the temperature of the first coupling reaction is controlled at 5-10° C., and baking soda is used to adjust the pH value to 6.3-6.

5.

6. The preparation process of gray-black reactive dye according to claim 5, wherein The reaction time in the primary coupling reaction is 3 to 4 hours, and the molar ratio of baking soda to gamma acid is (0.8 to 1.1):

1.

7. The preparation process of gray-black reactive dye according to claim 1, wherein In the step 4), ice is added to control the reaction temperature to 0-5° C.; the molar ratio of hydrochloric acid, phosphoric acid, sodium nitrite and gamma acid is (1-1.5):(0.5-1):(0.95-1.05):

1.

8. The preparation process of gray-black reactive dye according to claim 1, wherein In the step 5), after adding 1-(4-sulfonylphenyl)-3-carboxyl-5-pyrazolone dry powder, the pH value is adjusted to 6.5-7.0, and the reaction temperature is controlled to 10-15°C.

9. The preparation process of gray-black reactive dye according to claim 1, wherein In the step 6), copper chloride powder is added to the color base obtained in the step 5), the temperature is kept at 85-90° C., the pH value is adjusted to 7.5-7.8, and a complex reaction is carried out; after the reaction is carried out for 8-10 hours to the end point, the temperature is lowered to 30-35° C. and the pH value is adjusted to 6.0-6.5, diatomaceous earth is added and filtered, and the filtrate is the dye stock.

10. The preparation process of gray-black reactive dye according to claim 1, wherein In the steps 1) to 6), the molar ratio of 2,5-dimethoxy para-ester, gamma acid, 1-(4-sulfonic acid phenyl)-3-carboxy-5-pyrazolone and copper chloride is (0.98-1.05):1:(0.95-1):(1.05-1.2).

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