Preparation process of metal complex black dye

Abstract

The invention discloses a preparation process of a metal complex black dye. The main reaction route comprises the following steps: diazotizing 2-amino-4-nitrophenol, coupling with H acid to obtain a color base, adding copper acetate into the color base, carrying out high-temperature complexing to obtain a complexing product, cooling, carrying out primary condensation with cyanuric chloride, carrying out secondary condensation with para-ester, and filtering to obtain a dye raw stock. The metal complex black dye provided by the invention is fine in preparation process, short in production period, small in amount of generated wastewater and low in spray drying energy consumption, the prepared dye is high in purity, low in insoluble substance residue, low in fixation temperature requirement during application, good in fixation rate and excellent in fastness, and a fabric is bright in color and can show charming blue tone after application.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of synthetic dyes, and particularly relates to a preparation process of a metal complex reactive dye. Background Art

[0002] Metal complex dyes are a class of dyes that form stable complex structures through the reaction of dye molecules with metal ions (such as chromium, cobalt, nickel, copper, etc.). They appear more frequently in the categories of reactive dyes and acid dyes. Such dyes have excellent color fastness, light fastness, and wash fastness, and are widely used in the fields of textiles, leather, inks, etc.

[0003] Reactive Black 8 is a representative of metal complex dyes. This dye is mostly used for printing cotton, nylon, silk, and wool fabrics, and can also be used for dyeing. It has excellent fastness performance, good compatibility when used for compounding, and can show good blackness under deep dyeing conditions. However, its level dyeing property is general. Especially when used for blended fabrics such as polyester-cotton, there is a large color difference, and there are also problems such as low brightness, high requirements for fixing temperature and pH, and poor low-temperature fixing rate.

[0004] Regarding the synthesis technology of this dye and its similar structures, there have been reports for a long time. For example, the Chinese patent with the application number 200910029694.0 provides a Reactive Black K-BR and its cleaner production process, which improves the synthesis method of the chromophore, omits the salting-out process, produces less sewage during the synthesis process, and has an improved solubility. However, there are many side reaction residues, the purity is not high, and it requires deep processing by membrane treatment technology, resulting in wastewater generation during post-treatment and high costs; the Chinese patent with the application number 201511006222.5 provides a reactive grey dye and its preparation method, which uses an incomplete complexation technology to prepare the grey dye, solving the problem of residual multivalent chromium ions in the dye. However, the application of this technology will lead to incomplete chromophore reaction, reducing the dye purity and yield, and the mono-condensate of cyanuric chloride and ammonia water in the technical route requires post-treatment, generating a large amount of wastewater, which is not environmentally friendly and has high treatment costs. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation process of a metal complex black dye, which has a short production cycle, produces less wastewater, the obtained dye has high purity and low insoluble residue, can be fixed at low temperature during application with excellent fastness, and the fabric has bright colors after application, showing a charming blue tone.

[0006] The technical solution provided by the present invention is as follows:

[0007] A preparation process of a metal complex black dye, comprising the following steps:

[0008] 1) Water, liquid alkali, and sodium nitrite are successively added to 2-amino-4-nitrophenol, stirred and dissolved, and then dropped into hydrochloric acid, and a diazotization reaction is carried out to obtain a diazonium salt;

[0009] 2) Add dry H-acid to the diazonium salt, then add it to the alkaline solution, adjust the pH, and perform an alkaline coupling reaction to obtain the chromophore;

[0010] 3) Add copper acetate and a catalyst to the chromophore, adjust the pH with liquid alkali, and perform a complexation reaction to obtain the complex material;

[0011] 4) Add ice and water to cyanuric chloride for pulping, then add the complex material, adjust the pH with sodium bicarbonate, and perform a first condensation reaction to obtain the first-condensed material;

[0012] 5) Add p-ester to the first-condensed material, adjust the pH with liquid alkali, perform a second condensation reaction to obtain the second-condensed material, and then filter. The filtrate is the original dye paste;

[0013] The structural formula of the metal complex black dye is as follows:

[0014]

[0015] In step 1) of the present invention, 2-amino-4-nitrophenol is slightly soluble in water. First, adjust the pH with liquid alkali, which can improve the water solubility to a certain extent and enhance the reaction conversion effect. The dosage of liquid alkali is about 0.5 - 1.0 times the molar dosage of 2-amino-4-nitrophenol, and then add sodium nitrite. And the diazotization reaction is carried out at low temperature. Too high a temperature will cause the decomposition of the diazonium salt. The main reaction equation is:

[0016]

[0017] Preferably, in step 1), after adjusting the pH of the liquid alkali to 8.0 - 9.0, add sodium nitrite.

[0018] Preferably, in step 1), the reaction temperature is 5 - 10 °C and the reaction time is 1 - 2 h.

[0019] Preferably, in step 1), the molar ratio of hydrochloric acid, sodium nitrite to 2-amino-4-nitrophenol is (2.5 - 3.5):(1 - 1.1):1.

[0020] In step 2) of the present invention, the fluidity of the coupling process between the diazonium salt and H-acid is poor. Adding a dispersant can reduce the viscosity of the material and improve the contact effect of the material. And a stable alkaline environment is more conducive to the alkaline coupling reaction, making it easier for the diazo bond position of the diazonium salt to connect to the ortho position of the hydroxyl group, thereby increasing the conversion rate. The main reaction equation is:

[0021]

[0022] Preferably, in step 2), prepare 10% sodium carbonate solution as the bottom liquid to provide a stable alkaline environment, and the molar dosage is 1.5 - 2.0 times that of 2-amino-4-nitrophenol.

[0023] Preferably, in step 2), dispersant MF is added in advance, and the amount of dispersant MF is 0.005 to 0.02 times the mass of 10% pure alkali solution.

[0024] Preferably, in step 2), the molar ratio of 2-amino-4-nitrophenol to H acid is (1-1.1):1, the reaction pH is 7.5-8.0, the reaction temperature is 5-10° C., and the reaction time is 4-8 h.

[0025] In step 3) of the present invention, the conventional technology uses a chromium metal compound to complex with the color base, which is difficult to react. Even under the condition of using a catalyst, it still takes a relatively long time, and the final dye is gray to black, which is not bright enough. The present invention uses copper acetate to provide a coordinated metal copper ion, which has good water solubility, reacts with the color base, and has low complexation difficulty. The acetate ions released after the coordination can form a buffer salt with other alkali metal ions to achieve the effect of balancing acid and base. A catalyst is added to further improve the conversion efficiency and reduce the production cycle. The obtained dye is blue to black, bright in color, and has a relatively wide audience. The main reaction equation is:

[0026]

[0027] Preferably, in step 3), the molar ratio of copper acetate to H acid is (0.95-1.05):1.

[0028] Preferably, in step 3), the catalyst is selected from 2,2'-bipyridine, 4,4'-bipyridine or a mixture of the two, and the amount used is 1-5% of the mass of the copper acetate.

[0029] Preferably, in step 3), the reaction pH is 8.0-9.0, the reaction temperature is 80-85° C., and the reaction time is 6-8 h.

[0030] Preferably, in step 3), after the reaction is complete, the temperature is lowered to 10° C., and the pH is adjusted to 5.5 to 6.0 with hydrochloric acid.

[0031] In step 4) of the present invention, cyanuric chloride is added to crushed ice to improve fineness, increase contact area, and promote reaction. The main reaction equation is:

[0032]

[0033] Preferably, in step 4), the molar ratio of cyanuric chloride to H acid is (0.93-0.98):1, the reaction pH is 3.0-4.0, the reaction temperature is 10-15° C., and the reaction time is 4-6 h.

[0034] In step 5) of the present invention, after the reaction is completed, a simple filtration process is added to remove the insoluble substances in the original pulp. The main reaction equation is:

[0035]

[0036] Preferably, in the said step 5), the molar ratio of para-ester to H-acid is (0.92 - 0.96):1, the reaction pH is 7.0 - 7.5, the reaction temperature is 45 - 50 °C, and the reaction time is 6 - 10 h.

[0037] Preferably, in the said step 5), diatomite is used for adsorption and filtration, and the dosage of diatomite is 0.1 - 1% of the mass of the slurry.

[0038] Compared with the traditional process, the advantages of the preparation process of the black dye provided by the present invention are as follows:

[0039] (1) The production cycle is short, the conversion effect of the unit reaction is good, the purity is high, and the generation amount of the three wastes, especially the wastewater, is low;

[0040] (2) The yield and solid content of the original pulp are high, the residue of insoluble substances is low, it is stable in storage in the liquid state, and the energy consumption for spray drying is low;

[0041] (3) The dye has relatively excellent fastness, good fixation rate, low requirement for fixation temperature, and the fabric is bright and can show a charming blue tone. Specific embodiments

[0042] Example 1

[0043] The preparation process of the metal complex black dye provided by this example includes the following steps:

[0044] 1) Add 3000 kg of bottom water to a 5-cubic-meter dissolution pot, put in 350 kg of 2-amino-4-nitrophenol, stir, adjust the pH to 8.0 - 9.0 with 30% liquid alkali, and add 160 kg of sodium nitrite to ensure dissolution. Add 830 kg of 30% hydrochloric acid and 500 kg of crushed ice to a 10-cubic-meter diazotization pot, slowly add the 2-amino-4-nitrophenol solution, control the temperature at 5 - 10 °C, finish adding in about 10 minutes, and then react for 1.5 h to obtain the diazonium salt by diazotization reaction, and add 885 kg of H-acid dry powder and stir evenly.

[0045] 2) Prepare 4300 kg of 10% soda ash solution in a 20-cubic-meter reaction pot, add 45 kg of dispersant MF, stir evenly, quickly add the mixed materials in the 10-cubic-meter diazotization pot, maintain the pH at 7.5 - 8.0 with 20% soda ash solution after adding, keep the temperature at 5 - 10 °C, and carry out the coupling reaction for 6 h to obtain the chromophore.

[0046] 3) After the coupling is completed, 400 kg of copper acetate is added to the chromophore, and the temperature is slowly raised. When the temperature reaches 80 °C, 5 kg of 2,2'-bipyridine and 5 kg of 4,4'-bipyridine are added. Keep the temperature at 80 - 85 °C, and maintain the pH at 8.0 - 9.0 with 10% liquid caustic soda. React for 8 h until the complexation is complete, then cool down to 10 °C, and adjust the pH back to 5.5 - 6.0 with hydrochloric acid to obtain the complex material.

[0047] 4) Add 800 kg of bottom water and 1200 kg of crushed ice to a 20-cubic-meter condensation pot, put in 400 kg of cyanuric chloride and stir to make a slurry, add the complex material, keep the temperature at 10 - 15 °C, and maintain the pH at 3.0 - 4.0 with sodium bicarbonate. React for 5 h until the first condensation end point is reached to obtain the first-condensed material.

[0048] 5) Then slowly raise the temperature. When the temperature reaches 40 °C, add 630 kg of p-ester, keep the temperature at 45 - 50 °C, and maintain the pH at 7.0 - 7.5 with 20% sodium carbonate solution. React for 8 h until the end point.

[0049] 6) Finally, add 100 kg of diatomaceous earth, stir for 1 h, filter, and collect the filtrate, which is the original dye paste.

[0050] 7) After standardizing the original paste, spray dry it to obtain the dry powder of the metal complex black dye.

[0051] Example 2

[0052] The difference from Example 1 is that in step 1), the dosage of 2-amino-4-nitrophenol is 345 kg and the dosage of H acid is 880 kg.

[0053] Example 3

[0054] The difference from Example 1 is that in step 3), the dosage of 2,2'-bipyridine is 4 kg and the dosage of 4,4'-bipyridine is 4 kg.

[0055] Comparative Example 1

[0056] The difference from Example 1 is that in step 3) of the complexation process, no catalyst is added, and step 6) is omitted, that is, the original paste is not filtered through diatomaceous earth.

[0057] Comparative Example 2

[0058] The difference from Example 1 is that in step 1), no liquid caustic soda is added to adjust the pH before the diazotization reaction, and the dosage of 30% hydrochloric acid is adjusted to 350 kg.

[0059] Comparative Example 3

[0060] The difference from Example 1 is that in step 2), dispersant MF is not added during the coupling process.

[0061] Comparative Example 4

[0062] Prepare reactive black K - BR according to the process in Example 1 of the Chinese patent with application number 200910029694.0.

[0063] Comparative Example 5

[0064] Prepare reactive grey dye according to the process in Example 1 of the Chinese patent with application number 201511006222.5.

[0065] Compare the black reactive dye products prepared in Examples 1 - 3 with Comparative Examples 1 - 5. Table 1 shows the purity of the dye stock solution, solid content, relative yield (taking Example 1 as the standard), and mass fraction of insoluble substances; Table 2 shows the test data of some fastness properties after dye application, relative fixation rate at a fixation temperature of 60°C (taking Example 1 as the standard), and fabric shade.

[0066] Table 1 Purity of the dye stock solution, solid content, relative yield (taking Example 1 as the standard), and mass fraction of insoluble substances prepared in Examples 1 - 3 and Comparative Examples 1 - 5

[0067]

[0068] Table 2 Test data of some fastness properties after dye application, relative fixation rate at a fixation temperature of 60°C (taking Example 1 as the standard), and fabric shade prepared in Examples 1 - 3 and Comparative Examples 1 - 5

[0069]

[0070]

[0071] In Comparative Example 2, membrane treatment is required after the stock solution is completed. Although this process can improve the dye purity to a certain extent and reduce soluble impurities, a large amount of high - salt and high - COD wastewater will be generated during the treatment process, resulting in high biochemical pressure. In Comparative Example 3, during the treatment of cyanuric chloride and ammonia monoconjugate, two expansions are required to remove the supernatant, which is not only time - consuming and laborious but also generates a lot of high - ammonia - nitrogen wastewater, causing pollution as well. As can be seen from Table 1, the solid content in Examples 1 - 3 is slightly higher than that in Comparative Examples 4 and 5, which has certain advantages in spray drying, can save some energy consumption, the purity and yield are higher than those in Comparative Examples 1 - 5, and the residue of insoluble substances is lower than that in Comparative Examples 1, 4, and 5. This shows that the present invention has better reaction effects and material conversion rates, and the additional conventional diatomaceous earth adsorption and filtration also plays a role. From the test data in Table 2, it can be found that the fixation rate of the dye of the present invention at 60°C is significantly better than that of the comparative products, has good low - temperature fixation ability, and excellent fastness properties, higher than those of similar products, with strong market competitiveness.

[0072] In summary, the preparation process provided by the present invention can solve the deficiencies of the current Reactive Black 8 and its process, such as high requirement for fixing temperature, graying of the fabric after coloring, lack of vividness, long production cycle, large amount of wastewater, and low yield, etc.

Claims

1. A process for preparing a metal complex black dye, characterized in that: The steps include: 1) Water, liquid alkali and sodium nitrite are added to 2-amino-4-nitrophenol in sequence, and after stirring to dissolve, the mixture is added dropwise to hydrochloric acid to undergo diazotization reaction to obtain a diazonium salt; 2) Add H acid powder to the diazonium salt, add it to the alkali solution, adjust the pH, and perform alkaline coupling reaction to obtain the chromophore; 3) adding copper acetate and a catalyst to the color base, adjusting the pH with liquid alkali, and performing a complex reaction to obtain a complex material; 4) Add ice and water to cyanuric chloride for slurrying, then add the complexing material, adjust the pH with baking soda, and conduct a condensation reaction to obtain a condensed material; 5) Add the para-ester to the first shrinkage product, adjust the pH with alkali solution, conduct a secondary condensation reaction to obtain the second shrinkage product, and then filter it. The filtrate is the dye slurry; The structural formula of the metal complex black dye is as follows:

2. The process for preparing the metal complex black dye according to claim 1, characterized in that: In the step 1), sodium nitrite is added after the liquid alkali is adjusted to pH 8.0-9.0, the molar ratio of hydrochloric acid, sodium nitrite and 2-amino-4-nitrophenol is (2.5-3.5):(1-1.1):1, the reaction temperature is 5-10° C., and the reaction time is 1-2 hours.

3. The preparation process of the metal complex black dye according to claim 1, characterized in that: In the step 2), the alkali solution includes 10% pure alkali solution and dispersant MF, the molar amount of pure alkali is 1.5 to 2.0 times that of 2-amino-4-nitrophenol, and the amount of dispersant MF is 0.005 to 0.02 times the mass of the 10% pure alkali solution; and 20% pure alkali solution is used to adjust the pH.

4. The process for preparing the metal complex black dye according to claim 1, characterized in that: In the step 2), the molar ratio of 2-amino-4-nitrophenol to H acid is (1-1.1):1, the reaction pH is 7.5-8.0, the reaction temperature is 5-10° C., and the reaction time is 4-8 hours.

5. The process for preparing the metal complex black dye according to claim 1, characterized in that: In the step 3), the molar ratio of the copper acetate to the H acid is (0.95-1.05):1, the catalyst is selected from 2,2'-bipyridine, 4,4'-bipyridine or a mixture of the two, and the amount used is 1-5% of the mass of the copper acetate. The reaction pH is 8.0-9.0, the reaction temperature is 80-85°C, the reaction time is 6-8h, and after the reaction is complete, the temperature is lowered to 10°C, and the pH is adjusted to 5.5-6.0 with hydrochloric acid.

6. The process for preparing the metal complex black dye according to claim 1, characterized in that: In the step 4), the molar ratio of cyanuric chloride to H acid is (0.93-0.98):1, the reaction pH is 3.0-4.0, the reaction temperature is 10-15° C., and the reaction time is 4-6 hours.

7. The process for preparing the metal complex black dye according to claim 1, characterized in that: In the step 5), the molar ratio of the para-ester to the H acid is (0.92-0.96):1, the reaction pH is 7.0-7.5, the reaction temperature is 45-50° C., and the reaction time is 6-10 hours.

8. The process for preparing the metal complex black dye according to claim 1, characterized in that: In the step 5), diatomaceous earth is used for filtration, and the amount of diatomaceous earth used is 0.1-1% of the mass of the slurry.

9. The process for preparing the metal complex black dye according to any one of claims 1 to 8, characterized in that: The mass fraction of insoluble matter in the metal complex black dye is ≤0.05%.

10. The process for preparing the metal complex black dye according to any one of claims 1 to 8, characterized in that: The color tone of the metal complex black dye is blue-black.

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