A process for preparing a colorant through an intermediate 2,6-dihydroxytoluene

Abstract

The present invention provides a process for preparing a colorant by an intermediate 2,6-dihydroxytoluene, and belongs to the field of colorant preparation; its processing process comprises the following steps: adding sodium nitrite solution to react and preparing intermediate A; dissolving and adding intermediate A to react and preparing intermediate B; dissolving intermediate B and adding concentrated sulfuric acid to react; adding polyethylene glycol to prepare a modifier and modify collagen. The present invention is first reacted by sulfanilic acid and sodium nitrite in an acidic environment, so that the amino group is converted into a diazo group, and then coupled with 2,6-dihydroxytoluene in a weakly acidic environment to generate an azo group, because the hydroxyl group of 2,6-dihydroxytoluene is used as an electricity-donating group, the electron cloud density of the benzene ring can be enhanced, so that the azo group is more stable, so that the stability of the color can be maintained, and then the weather resistance of the obtained colorant can be improved.

Description

Technical Field

[0001] The invention relates to the field of colorant preparation, and in particular to a process for preparing a colorant through an intermediate 2,6-dihydroxytoluene. Background Art

[0002] 2,6-Dihydroxytoluene is an organic compound and a toluene derivative containing two hydroxyl functional groups, one of which is located at the 2 position of the benzene ring and the other at the 6 position. As an important intermediate, it is widely used in the chemical, pharmaceutical, dye and other industries.

[0003] At present, although it is known that 2,6-dihydroxytoluene has certain applications in the manufacture of pigments and dyes, its potential in the preparation of new colorants with specific performance requirements has not been fully explored, especially in combination with polymer carriers to form composite materials with certain colors, such as for the coloring of plastics, coatings, inks, etc. In addition, due to the unstable chemical structure of existing colorants, they are prone to oxidation, hydrolysis and other reactions, resulting in fading or discoloration, reducing their weather resistance and color fastness.

[0004] Therefore, it is urgent to propose a process for preparing a colorant through the intermediate 2,6-dihydroxytoluene with good weather resistance and strong color fastness. Summary of the invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a process for preparing a colorant through the intermediate 2,6-dihydroxytoluene.

[0006] A process for preparing a colorant through an intermediate 2,6-dihydroxytoluene comprises the following steps:

[0007] S1: Add sodium nitrite solution to react and prepare intermediate A

[0008] Dissolving p-aminobenzenesulfonic acid and sodium nitrite in glacial acetic acid and deionized water respectively to obtain p-aminobenzenesulfonic acid solution and sodium nitrite solution, and then adding the sodium nitrite solution to the p-aminobenzenesulfonic acid solution to react to obtain intermediate A;

[0009] S2: Dissolve and add intermediate A to react and prepare intermediate B

[0010] Dissolve 2,6-dihydroxytoluene in an ethanol solution, add sulfuric acid to adjust the pH, and then add the intermediate A to react to obtain intermediate B;

[0011] S3: Dissolve intermediate B and add concentrated sulfuric acid to react

[0012] The intermediate B is dissolved in dimethyl sulfoxide, and concentrated sulfuric acid is added to react, and the intermediate C is obtained after centrifugal separation, washing and drying;

[0013] S4: Adding polyethylene glycol to prepare a modifier and modifying collagen

[0014] Polyethylene glycol and dibutyltin dilaurate are added to isophorone diisocyanate for reaction, and 2,2-dihydroxymethylpropionic acid is added to continue the reaction to prepare a modifier, which is then added to the collagen solution for modification, and finally the intermediate C and sodium acetate are added to react to obtain a colorant.

[0015] Furthermore, S1 specifically includes the following steps:

[0016] S1.1: Add p-aminobenzenesulfonic acid and glacial acetic acid into a reactor at a solid-liquid ratio of 1 g: (10-20) mL, stir and mix evenly at room temperature, and fully dissolve to obtain a p-aminobenzenesulfonic acid solution;

[0017] S1.2: Sodium nitrite and deionized water are stirred and mixed at a solid-liquid ratio of 1 g: (10-20) mL to obtain a sodium nitrite solution;

[0018] S1.3: Add sulfuric acid solution to the above-mentioned p-aminobenzenesulfonic acid solution until the pH is adjusted to 3-4, and then drip the above-mentioned sodium nitrite solution into the reactor at a uniform rate while stirring to react with the p-aminobenzenesulfonic acid solution. After the addition is completed, continue stirring until the air pressure in the reactor no longer changes to obtain intermediate A.

[0019] Furthermore, S2 specifically includes the following steps:

[0020] S2.1: Stir and mix 2,6-dihydroxytoluene and ethanol solution at a solid-liquid ratio of 1 g: (20-30) mL, and after fully dissolving, obtain a 2,6-dihydroxytoluene solution;

[0021] S2.2: Add sulfuric acid solution to the above 2,6-dihydroxytoluene solution until the pH reaches 4-6, heat to 35-45°C, and then add intermediate A obtained in step S1.3 while stirring to react. Continue stirring for 1-2 hours, centrifuge, filter, wash and dry to obtain intermediate B.

[0022] Furthermore, S3 specifically includes the following steps:

[0023] S3.1: The intermediate B prepared in step S2.2 and dimethyl sulfoxide are stirred and mixed at a solid-liquid ratio of 1 g: (20-30) mL to fully dissolve to obtain an intermediate B solution;

[0024] S3.2: Place the intermediate B solution in a cold water bath at 5-8°C, and then drip concentrated sulfuric acid into the intermediate B solution at a uniform rate to react. After the dripping is complete, continue stirring for 40-50 minutes to obtain a mixed reaction solution;

[0025] S3.3: Place the above mixed reaction liquid in a centrifuge for centrifugal stratification, take out the organic phase, wash and dry it to obtain intermediate C.

[0026] Furthermore, S4 specifically includes the following steps:

[0027] S4.1: Add isophorone diisocyanate into a reactor, then add polyethylene glycol and dibutyltin dilaurate, heat to 70-80°C and stir to react for 1-2h;

[0028] S4.2: Keeping the temperature constant, add 2,2-dihydroxymethylpropionic acid to the reactor, continue stirring the reaction for 1-2 hours, cool to 40-50°C, add triethylamine to adjust the pH to 7-8, and obtain a modifier;

[0029] S4.3: Dissolve the collagen powder in deionized water to prepare a collagen solution with a concentration of 50-60%, then add the above-mentioned modifier to the collagen solution, heat to 60-70°C, and stir to react for 2-3 hours to obtain a modified collagen solution;

[0030] S4.4: Add the intermediate C obtained in step S3.3 to the above modified collagen solution, stir and mix, then add sodium acetate solution, heat to 70-80°C, react for 1-2h, then heat to 85-95°C until the pH no longer changes, stop heating, and naturally cool to room temperature to obtain a colorant.

[0031] Furthermore, the molar ratio of sodium nitrite to p-aminobenzenesulfonic acid is (1.3-1.5):1.

[0032] Furthermore, the molar ratio of 2,6-dihydroxytoluene to intermediate A is (1.2-1.6):1.

[0033] Furthermore, the molar ratio of concentrated sulfuric acid to intermediate B is (1.1-1.3):1.

[0034] Furthermore, the molar ratio of isophorone diisocyanate, polyethylene glycol and 2,2-dimethylol propionic acid is (1-2):1:1, and the added amount of dibutyltin dilaurate accounts for 0.6-0.8% of the total mass of isophorone diisocyanate and polyethylene glycol.

[0035] Furthermore, the mass ratio of the collagen solution to the modifier is (5-6):1, the mass ratio of the modified collagen solution, the intermediate C and the sodium acetate solution is (10-20):(3-5):1, and the concentration of the sodium acetate solution is 8-10%.

[0036] Compared with the prior art, the present invention has at least the following beneficial effects:

[0037] 1. The present invention first reacts p-aminobenzenesulfonic acid with sodium nitrite in an acidic environment to convert the amino group into a diazo group, and then couples the diazo group with 2,6-dihydroxytoluene in a weakly acidic environment to generate an azo group. Since the hydroxyl group of 2,6-dihydroxytoluene serves as an electron-donating group, the electron cloud density of the benzene ring can be enhanced, making the azo group more stable. At the same time, due to the steric hindrance effect, the hydroxyl groups at the 2 and 6 positions will not directly react with the azo group, which helps to keep the conjugated system of the azo group undisturbed, thereby maintaining the color stability and further improving the weather resistance of the prepared colorant.

[0038] 2. In the present invention, after coupling reaction of 2,6-dihydroxytoluene and diazotized p-aminobenzenesulfonic acid, the reaction is carried out with concentrated sulfuric acid under low temperature environment to introduce sulfonic acid group at the ortho position of 2,6 hydroxyl group. Since sulfonic acid group is a strongly polar functional group with negative charge, it can form strong hydrogen bond interaction with water molecules, thereby effectively improving the water solubility of the prepared colorant. In addition, since sulfonic acid group is almost completely ionized in water and converted into sulfonate radical, this ionic form is conducive to combining with cationic groups on the fiber surface, enhancing the attraction between the colorant and the fiber, thereby improving the adsorption capacity of the colorant on the fiber, and further effectively improving the color fastness of the colorant.

[0039] 3. The present invention uses isophorone diisocyanate and 2,2-dihydroxymethylpropionic acid as raw materials, reacts under the action of a catalyst of dibutyltin dilaurate to prepare a modifier, and then uses the modifier to modify collagen, and then mixes with intermediate C for reaction. The synthesized colorant is a protein-based colorant. After the collagen is modified and chain extended, cross-linking occurs between molecules, so that a three-dimensional network structure is formed between the molecules, which enhances the interaction between collagen molecules and improves the cohesive force of film formation, so that the intermediate C molecules are more firmly anchored in the collagen matrix and are not easily detached due to external conditions, thereby improving the color fastness of the prepared colorant. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art to make and use the present disclosure.

[0041] Figure 1 This is a process flow chart for preparing a colorant through the intermediate 2,6-dihydroxytoluene adopted in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following is a detailed description of a process for preparing a colorant through the intermediate 2,6-dihydroxytoluene provided by the present invention in conjunction with the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] A process for preparing a colorant through the intermediate 2,6-dihydroxytoluene, such as Figure 1 As shown, the following steps are included:

[0045] S1: Add sodium nitrite solution to react and prepare intermediate A

[0046] Add p-aminobenzenesulfonic acid and glacial acetic acid into a reactor at a solid-liquid ratio of 1g:10mL, stir and mix evenly at room temperature, fully dissolve, obtain p-aminobenzenesulfonic acid solution, set aside, then stir and mix sodium nitrite and deionized water at a solid-liquid ratio of 1g:10mL, fully dissolve, obtain sodium nitrite solution, set aside, then add sulfuric acid solution to the p-aminobenzenesulfonic acid solution until the pH is adjusted to 3, then drip the sodium nitrite solution into the reactor at a uniform speed while stirring, react with the p-aminobenzenesulfonic acid solution, after the dripping is completed, continue stirring until the air pressure in the reactor no longer changes, and obtain intermediate A, wherein the molar ratio of sodium nitrite to p-aminobenzenesulfonic acid is 1.3:1;

[0047] S2: Dissolve and add intermediate A to react and prepare intermediate B

[0048] 2,6-dihydroxytoluene and ethanol solution were stirred and mixed at a solid-liquid ratio of 1g:20mL, and after being fully dissolved, a 2,6-dihydroxytoluene solution was obtained, and then a sulfuric acid solution was added to the 2,6-dihydroxytoluene solution until the pH reached 4, and the solution was heated to 35°C, and then the intermediate A was added while stirring to react, and the stirring was continued for 1 hour, and then the intermediate B was obtained by centrifugation, filtration, washing and drying, wherein the molar ratio of 2,6-dihydroxytoluene to intermediate A was 1.2:1;

[0049] S3: Dissolve intermediate B and add concentrated sulfuric acid to react

[0050] The intermediate B and dimethyl sulfoxide are stirred and mixed at a solid-liquid ratio of 1g:20mL to fully dissolve to obtain an intermediate B solution, and then the intermediate B solution is placed in a cold water bath at 5°C, and concentrated sulfuric acid is uniformly dripped into the intermediate B solution to react. After the dropwise addition is completed, stirring is continued for 40-50 minutes to obtain a mixed reaction liquid, wherein the molar ratio of concentrated sulfuric acid to intermediate B is 1.1:1. Subsequently, the mixed reaction liquid is placed in a centrifuge for centrifugal stratification, the organic phase is taken out, and washed and dried to obtain intermediate C;

[0051] S4: Adding polyethylene glycol to prepare a modifier and modifying collagen

[0052] Add isophorone diisocyanate to the reactor, then add polyethylene glycol and dibutyl tin dilaurate, heat to 70°C and stir to react for 1 hour, then keep the temperature unchanged, add 2,2-dihydroxymethylpropionic acid to the reactor, continue to stir to react for 1 hour, cool to 40-50°C, add triethylamine to adjust the pH to 7, obtain a modifier for standby use, wherein the molar ratio of isophorone diisocyanate, polyethylene glycol and 2,2-dihydroxymethylpropionic acid is 1:1:1, and the amount of dibutyl tin dilaurate added accounts for 0.6% of the total mass of isophorone diisocyanate and polyethylene glycol. Subsequently, the collagen powder is dissolved in deionized water and mixed with A collagen solution with a concentration of 50% is prepared, and the modifier is added to the collagen solution, heated to 60°C, and stirred for reaction for 2 hours to obtain a modified collagen solution. Finally, the intermediate C is added to the modified collagen solution, stirred and mixed, and then a sodium acetate solution is added and heated to 70°C. The mixture is reacted for 1 hour, and then the temperature is raised to 85°C until the pH no longer changes. The heating is stopped, and the mixture is naturally cooled to room temperature to obtain a colorant, wherein the mass ratio of the collagen solution to the modifier is 5:1, the mass ratio of the modified collagen solution, the intermediate C and the sodium acetate solution is 10:3:1, and the concentration of the sodium acetate solution is 8%.

[0053] Performance Test:

[0054] The prepared colorant was mixed with polyvinyl alcohol in a mass ratio of 1:50, and stirred at 90° C. for 1.5 hours. After degassing in a centrifuge, the mixture was poured into a mold and dried at room temperature to obtain a colored composite film.

[0055] Then, the aging color fastness of the prepared color composite film was determined with reference to GB / T35256-2017, and the color fastness of the prepared color composite film was tested with reference to GB / T3920-2008, and the results are shown in Table 1 below.

[0056] Example 2

[0057] A process for preparing a colorant through the intermediate 2,6-dihydroxytoluene, such as Figure 1 As shown, the following steps are included:

[0058] S1: Add sodium nitrite solution to react and prepare intermediate A

[0059] Add p-aminobenzenesulfonic acid and glacial acetic acid into a reactor at a solid-liquid ratio of 1g:15mL, stir and mix evenly at room temperature, fully dissolve, obtain p-aminobenzenesulfonic acid solution, set aside, then stir and mix sodium nitrite and deionized water at a solid-liquid ratio of 1g:15mL, fully dissolve, obtain sodium nitrite solution, set aside, then add sulfuric acid solution to the p-aminobenzenesulfonic acid solution until the pH is adjusted to 3.5, then drip the sodium nitrite solution into the reactor at a uniform speed while stirring, react with the p-aminobenzenesulfonic acid solution, after the dripping is completed, continue stirring until the air pressure in the reactor no longer changes, and obtain intermediate A, wherein the molar ratio of sodium nitrite to p-aminobenzenesulfonic acid is 1.4:1;

[0060] S2: Dissolve and add intermediate A to react and prepare intermediate B

[0061] 2,6-dihydroxytoluene and ethanol solution were stirred and mixed at a solid-liquid ratio of 1g:25mL, and after being fully dissolved, a 2,6-dihydroxytoluene solution was obtained, and then a sulfuric acid solution was added to the 2,6-dihydroxytoluene solution until the pH reached 5, and the solution was heated to 40°C, and the intermediate A was added while stirring to react, and the stirring was continued for 1.5 hours, and then the intermediate B was obtained by centrifugation, filtration, washing and drying, wherein the molar ratio of 2,6-dihydroxytoluene to intermediate A was 1.4:1;

[0062] S3: Dissolve intermediate B and add concentrated sulfuric acid to react

[0063] The intermediate B and dimethyl sulfoxide are stirred and mixed at a solid-liquid ratio of 1g:25mL to fully dissolve to obtain an intermediate B solution, and then the intermediate B solution is placed in a cold water bath at 6.5°C, and concentrated sulfuric acid is uniformly dripped into the intermediate B solution to react. After the dropwise addition is completed, stirring is continued for 45 minutes to obtain a mixed reaction liquid, wherein the molar ratio of concentrated sulfuric acid to intermediate B is 1.2:1. Subsequently, the mixed reaction liquid is placed in a centrifuge for centrifugal stratification, the organic phase is taken out, and washed and dried to obtain intermediate C;

[0064] S4: Adding polyethylene glycol to prepare a modifier and modifying collagen

[0065] Add isophorone diisocyanate to the reactor, then add polyethylene glycol and dibutyl tin dilaurate, heat to 75°C and stir to react for 1.5h, then keep the temperature unchanged, add 2,2-dihydroxymethylpropionic acid to the reactor, continue to stir to react for 1.5h, cool to 45°C, add triethylamine to adjust the pH to 7.5, obtain a modifier for standby use, wherein the molar ratio of isophorone diisocyanate, polyethylene glycol and 2,2-dihydroxymethylpropionic acid is 1.5:1:1, and the amount of dibutyl tin dilaurate added accounts for 0.7% of the total mass of isophorone diisocyanate and polyethylene glycol. Subsequently, the collagen powder is dissolved in deionized water to prepare A collagen solution with a concentration of 55%, and then adding a modifier to the collagen solution, heating to 65°C, and stirring to react for 2.5 hours to obtain a modified collagen solution. Finally, the above-mentioned intermediate C is added to the modified collagen solution, stirred and mixed, and then a sodium acetate solution is added and heated to 75°C. The reaction is 1.5 hours, and then the temperature is raised to 90°C until the pH no longer changes. The heating is stopped and naturally cooled to room temperature to obtain a colorant, wherein the mass ratio of the collagen solution to the modifier is 5.5:1, the mass ratio of the modified collagen solution, the intermediate C and the sodium acetate solution is 15:4:1, and the concentration of the sodium acetate solution is 9%.

[0066] Performance Test:

[0067] The prepared colorant was mixed with polyvinyl alcohol in a mass ratio of 1:50, and stirred at 90° C. for 1.5 hours. After degassing in a centrifuge, the mixture was poured into a mold and dried at room temperature to obtain a colored composite film.

[0068] Then, the aging color fastness of the prepared color composite film was determined with reference to GB / T35256-2017, and the color fastness of the prepared color composite film was tested with reference to GB / T3920-2008, and the results are shown in Table 1 below.

[0069] Example 3

[0070] A process for preparing a colorant through the intermediate 2,6-dihydroxytoluene, such as Figure 1 As shown, the following steps are included:

[0071] S1: Add sodium nitrite solution to react and prepare intermediate A

[0072] Add p-aminobenzenesulfonic acid and glacial acetic acid into a reactor at a solid-liquid ratio of 1g:20mL, stir and mix evenly at room temperature, fully dissolve to obtain a p-aminobenzenesulfonic acid solution, and set aside; then stir and mix sodium nitrite and deionized water at a solid-liquid ratio of 1g:20mL, fully dissolve to obtain a sodium nitrite solution, and set aside; then add sulfuric acid solution to the p-aminobenzenesulfonic acid solution until the pH is adjusted to 4; then drip the sodium nitrite solution into the reactor at a uniform speed while stirring to react with the p-aminobenzenesulfonic acid solution; after the dripping is completed, continue stirring until the air pressure in the reactor no longer changes to obtain intermediate A, wherein the molar ratio of sodium nitrite to p-aminobenzenesulfonic acid is 1.5:1;

[0073] S2: Dissolve and add intermediate A to react and prepare intermediate B

[0074] 2,6-dihydroxytoluene and ethanol solution were stirred and mixed at a solid-liquid ratio of 1g:30mL, and after being fully dissolved, a 2,6-dihydroxytoluene solution was obtained, and then a sulfuric acid solution was added to the 2,6-dihydroxytoluene solution until the pH reached 6, and the solution was heated to 45°C, and then the intermediate A was added while stirring to react, and the stirring was continued for 2h, and then the intermediate B was obtained by centrifugation, filtration, washing and drying, wherein the molar ratio of 2,6-dihydroxytoluene to intermediate A was 1.6:1;

[0075] S3: Dissolve intermediate B and add concentrated sulfuric acid to react

[0076] The intermediate B and dimethyl sulfoxide are stirred and mixed at a solid-liquid ratio of 1g:30mL to fully dissolve to obtain an intermediate B solution, and then the intermediate B solution is placed in a cold water bath at 8°C, and concentrated sulfuric acid is uniformly dripped into the intermediate B solution to react. After the dropwise addition is completed, stirring is continued for 50 minutes to obtain a mixed reaction liquid, wherein the molar ratio of concentrated sulfuric acid to intermediate B is 1.3:1. Subsequently, the mixed reaction liquid is placed in a centrifuge for centrifugal stratification, the organic phase is taken out, and washed and dried to obtain intermediate C;

[0077] S4: Adding polyethylene glycol to prepare a modifier and modifying collagen

[0078] Add isophorone diisocyanate to the reactor, then add polyethylene glycol and dibutyl tin dilaurate, heat to 80°C and stir to react for 2h, then keep the temperature unchanged, add 2,2-dihydroxymethylpropionic acid to the reactor, continue to stir to react for 2h, cool to 40-50°C, add triethylamine to adjust the pH to 8, and obtain a modifier for standby use, wherein the molar ratio of isophorone diisocyanate, polyethylene glycol and 2,2-dihydroxymethylpropionic acid is 2:1:1, and the amount of dibutyl tin dilaurate added accounts for 0.8% of the total mass of isophorone diisocyanate and polyethylene glycol. Subsequently, the collagen powder is dissolved in deionized water to prepare A collagen solution with a concentration of 60%, and then adding a modifier to the collagen solution, heating to 70°C, and stirring to react for 3 hours to obtain a modified collagen solution. Finally, the above-mentioned intermediate C is added to the modified collagen solution, stirred and mixed, and then a sodium acetate solution is added and heated to 80°C. React for 2 hours, and then the temperature is raised to 95°C until the pH no longer changes, and heating is stopped. Naturally cool to room temperature to obtain a colorant, wherein the mass ratio of the collagen solution to the modifier is 6:1, the mass ratio of the modified collagen solution, the intermediate C and the sodium acetate solution is 20:5:1, and the concentration of the sodium acetate solution is 10%.

[0079] Performance Test:

[0080] The prepared colorant was mixed with polyvinyl alcohol in a mass ratio of 1:50, and stirred at 90° C. for 1.5 hours. After degassing in a centrifuge, the mixture was poured into a mold and dried at room temperature to obtain a colored composite film.

[0081] Then, the color fastness to light aging of the prepared color composite film was determined with reference to GB / T35256-2017, and the color fastness to rubbing of the prepared color composite film was tested with reference to GB / T3920-2008, and the results are shown in Table 1 below.

[0082] Table 1: Summary of performance test results of Examples 1-3

[0083]

[0084] Comparative Example 1

[0085] The difference between this comparative example 1 and example 1 is that the intermediate B in step S3 is replaced by an equal amount of 2,6-dihydroxytoluene, and then a performance test is performed according to the performance test method in example 1, and the results are shown in Table 2 below.

[0086] Table 2: Comparison of performance test results of Example 1 and Comparative Example 1

[0087]

[0088] By comparing the performance test results of Example 1 and Comparative Example 1, it can be seen that the light aging color fastness grade of Comparative Example 1 is Grade 3, which is lower than Grade 5 in Example 1. It can be seen that by first reacting p-aminobenzenesulfonic acid with sodium nitrite in an acidic environment, the amino group is converted into a diazo group, and then coupled with 2,6-dihydroxytoluene in a weakly acidic environment to generate an azo group. Since the hydroxyl group of 2,6-dihydroxytoluene is used as an electron-donating group, the electron cloud density of the benzene ring can be enhanced, making the azo group more stable. At the same time, the hydroxyl groups at the 2,6 positions will not directly react with the azo group due to the steric hindrance effect, which helps to keep the conjugated system of the azo group undisturbed, thereby maintaining the color stability and further improving the weather resistance of the obtained colorant.

[0089] Comparative Example 2

[0090] The difference between this comparative example 2 and example 1 is that the intermediate C in step S4 is replaced by an equal amount of intermediate B, and then the performance test is performed according to the performance test method in example 1, and the results are shown in Table 3 below.

[0091] Table 3: Comparison of performance test results of Example 1 and Comparative Example 2

[0092]

[0093] From the performance test results of Comparative Example 1 and Comparative Example 2, it can be seen that the color fastness to light aging and the color fastness to rubbing of Comparative Example 2 are grade 2 and grade 3, respectively, which are lower than those of Example 1. It can be seen that after the 2,6-dihydroxytoluene is coupled with the diazotized p-aminobenzenesulfonic acid, it is reacted with concentrated sulfuric acid under a low temperature environment to introduce a sulfonic acid group at the ortho position of the 2,6-hydroxyl group. Since the sulfonic acid group is a strongly polar functional group with a negative charge, it can form a strong hydrogen bond interaction with water molecules, thereby effectively improving the water solubility of the prepared colorant. In addition, since the sulfonic acid group is almost completely ionized in water and converted into a sulfonate radical, this ionic form is conducive to combining with the cationic groups on the fiber surface, enhancing the attraction between the colorant and the fiber, thereby improving the adsorption capacity of the colorant on the fiber, and further effectively improving the color fastness of the colorant.

[0094] Comparative Example 3

[0095] The difference between this comparative example 3 and Example 1 is that the modified collagen solution in step S4 is replaced by an equal amount of collagen solution, that is, the collagen is not modified, and the collagen solution is directly used to react with the intermediate C, and then the performance test is carried out according to the performance test method in Example 1, and the results are shown in Table 4 below.

[0096] Table 3: Comparison of performance test results of Example 1 and Comparative Example 3

[0097]

[0098] From the performance test results of Comparative Example 1 and Comparative Example 3, it can be seen that the color fastness to light aging and the color fastness to rubbing of Comparative Example 3 are level 3 and level 2, respectively, both lower than that of Example 1. It can be seen that by first using isophorone diisocyanate and 2,2-dihydroxymethylpropionic acid as raw materials, reacting under the catalyst of dibutyltin dilaurate to prepare a modifier, and then using the modifier to modify collagen, and then mixing with intermediate C for reaction, the synthesized colorant is a protein-based colorant. After the collagen is modified and chain extended, cross-linking occurs between molecules, so that a three-dimensional network structure is formed between molecules, which enhances the interaction between collagen molecules and improves the cohesive force of film formation, so that the intermediate C molecules are more firmly anchored in the collagen matrix and are not easily detached due to external conditions, thereby improving the color fastness of the prepared colorant.

[0099] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A process for preparing a colorant through an intermediate 2,6-dihydroxytoluene, characterized in that: The steps include: S1: Add sodium nitrite solution to react and prepare intermediate A Dissolving p-aminobenzenesulfonic acid and sodium nitrite in glacial acetic acid and deionized water respectively to obtain p-aminobenzenesulfonic acid solution and sodium nitrite solution, and then adding the sodium nitrite solution to the p-aminobenzenesulfonic acid solution to react to obtain intermediate A; S2: Dissolve and add intermediate A to react and prepare intermediate B Dissolve 2,6-dihydroxytoluene in an ethanol solution, add sulfuric acid to adjust the pH, and then add the intermediate A to react to obtain intermediate B; S3: Dissolve intermediate B and add concentrated sulfuric acid to react The intermediate B is dissolved in dimethyl sulfoxide, and concentrated sulfuric acid is added to react, and the intermediate C is obtained after centrifugal separation, washing and drying; S4: Adding polyethylene glycol to prepare a modifier and modifying collagen Adding polyethylene glycol and dibutyltin dilaurate to isophorone diisocyanate for reaction, then adding 2,2-dihydroxymethylpropionic acid for further reaction to prepare a modifier, then adding it to the collagen solution for modification, and finally adding the intermediate C and sodium acetate for reaction to obtain a colorant; S2 specifically includes the following steps: S2.1: Stir and mix 2,6-dihydroxytoluene and ethanol solution at a solid-liquid ratio of 1 g: (20-30) mL, and after fully dissolving, obtain a 2,6-dihydroxytoluene solution; S2.2: Add sulfuric acid solution to the above 2,6-dihydroxytoluene solution until the pH reaches 4-6, heat to 35-45°C, then add intermediate A obtained in step S1.3 while stirring to react, continue stirring for 1-2 hours, centrifuge, filter, wash and dry to obtain intermediate B; S3 specifically includes the following steps: S3.1: The intermediate B prepared in step S2.2 and dimethyl sulfoxide are stirred and mixed at a solid-liquid ratio of 1 g: (20-30) mL to fully dissolve to obtain an intermediate B solution; S3.2: Place the intermediate B solution in a cold water bath at 5-8°C, and then drip concentrated sulfuric acid into the intermediate B solution at a uniform rate to react. After the dripping is complete, continue stirring for 40-50 minutes to obtain a mixed reaction solution; S3.3: Place the mixed reaction solution in a centrifuge for centrifugal separation, take out the organic phase, wash and dry it to obtain intermediate C; S4 specifically includes the following steps: S4.1: Add isophorone diisocyanate into a reactor, then add polyethylene glycol and dibutyltin dilaurate, heat to 70-80°C and stir to react for 1-2h; S4.2: Keeping the temperature constant, add 2,2-dihydroxymethylpropionic acid to the reactor, continue stirring the reaction for 1-2 hours, cool to 40-50°C, add triethylamine to adjust the pH to 7-8, and obtain a modifier; S4.3: Dissolve the collagen powder in deionized water to prepare a collagen solution with a concentration of 50-60%, then add the above-mentioned modifier to the collagen solution, heat to 60-70°C, and stir to react for 2-3 hours to obtain a modified collagen solution; S4.4: Add the intermediate C obtained in step S3.3 to the modified collagen solution, stir and mix, then add the sodium acetate solution, heat to 70-80°C, react for 1-2h, then heat to 85-95°C until the pH no longer changes, stop heating, and naturally cool to room temperature to obtain a colorant; The molar ratio of 2,6-dihydroxytoluene to intermediate A is (1.2-1.6):1; The molar ratio of isophorone diisocyanate, polyethylene glycol and 2,2-dimethylol propionic acid is (1-2): 1:1, and the amount of dibutyltin dilaurate added accounts for 0.6-0.8% of the total mass of isophorone diisocyanate and polyethylene glycol; The mass ratio of the collagen solution to the modifier is (5-6):1, the mass ratio of the modified collagen solution, the intermediate C and the sodium acetate solution is (10-20):(3-5):1, and the concentration of the sodium acetate solution is 8-10%.

2. A process for preparing a colorant through the intermediate 2,6-dihydroxytoluene according to claim 1, characterized in that: S1 specifically includes the following steps: S1.1: Add p-aminobenzenesulfonic acid and glacial acetic acid into a reactor at a solid-liquid ratio of 1 g: (10-20) mL, stir and mix evenly at room temperature, and fully dissolve to obtain a p-aminobenzenesulfonic acid solution; S1.2: Sodium nitrite and deionized water are stirred and mixed at a solid-liquid ratio of 1 g: (10-20) mL to obtain a sodium nitrite solution; S1.3: Add sulfuric acid solution to the above-mentioned p-aminobenzenesulfonic acid solution until the pH is adjusted to 3-4, and then drip the above-mentioned sodium nitrite solution into the reactor at a uniform rate while stirring to react with the p-aminobenzenesulfonic acid solution. After the addition is completed, continue stirring until the air pressure in the reactor no longer changes to obtain intermediate A.

3. A process for preparing a colorant through the intermediate 2,6-dihydroxytoluene according to claim 2, characterized in that: The molar ratio of sodium nitrite to p-aminobenzenesulfonic acid is (1.3-1.5):

1.

4. A process for preparing a colorant through the intermediate 2,6-dihydroxytoluene according to claim 1, characterized in that: The molar ratio of concentrated sulfuric acid to intermediate B is (1.1-1.3):1.

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