Cationic dyes and process for their preparation

Abstract

This invention discloses a cationic dye and its preparation method, belonging to the field of dye technology and patent classification number C09B26 / 04. The method uses 2-amino-4-nitrophenol as a starting material, which undergoes diazotization and coupling with N-ethyl-N-(2-hydroxyethyl)aniline to obtain an azo precursor containing dihydroxyl groups. Subsequently, this precursor undergoes etherification, silanization, and quaternization reactions sequentially with epichlorohydrin, γ-aminopropyltriethoxysilane, and diethyl 2-bromoethylphosphonate to generate a dye intermediate containing siloxane and quaternary ammonium salt groups. Finally, by adding tetraethyl orthosilicate and tributyl borate, a sol-gel reaction is carried out under acidic conditions to form a nano-borosilicate coated structure. After precipitation, washing, and drying, the final product is obtained. The cationic dye prepared by this invention exhibits good alkali resistance.

Description

Technical Field

[0001] This invention relates to the field of novel functional dyes, belonging to patent classification number C09B26 / 04, specifically to a cationic dye and its preparation method. Background Technology

[0002] Cationic dyes, as specialized dyes for polyolefin synthetic fibers, have become indispensable key chemical raw materials in the textile printing and dyeing industry due to their advantages such as a complete color spectrum, high color intensity, fast dyeing rate, and simple dyeing process. They are widely used in the dyeing and processing of civilian textile fabrics, industrial textile products, and functional textile new materials. With the textile industry developing towards high efficiency, green practices, and functionalization, the production processes in the printing and dyeing industry are constantly being optimized and upgraded. Processes such as the alkali-oxygen one-bath method, alkaline reduction cleaning, and alkaline co-bath dyeing have become the mainstream processes in textile printing and dyeing at present because they can significantly shorten the production process, improve production efficiency, and reduce the amount of auxiliaries used. These processes require the dyes used to maintain a stable chemical structure and application performance in a medium-strong alkaline system with pH ≥ 9. In the molecular structure of existing cationic dyes, both the core chromophore and the cationic functional sites are highly sensitive to alkaline environments. In alkaline systems, hydroxyl ions readily launch nucleophilic attacks on the chromophore of the dye, causing the chemical bonds of the chromophore to break and the structure to be destroyed. This directly leads to a decrease in the dye's color development ability, color shift, or even complete loss of color. At the same time, the cationic active sites of cationic dyes are mostly formed by quaternization of amino groups. Such structures are prone to hydrolysis and deactivation or charge imbalance under alkaline conditions, which greatly reduces the binding ability of the dye to the anionic sites of the fiber. This not only causes a significant decrease in the dye uptake rate but also leads to a deterioration in various fastness indicators of the dyed fabric, such as light exposure, rubbing, and washing. Summary of the Invention

[0003] The purpose of this invention is to provide a cationic dye and its preparation method to solve the technical problem of poor alkali resistance of cationic dyes mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for preparing a cationic dye includes the following steps:

[0006] (1) 2-Amino-4-nitrophenol was diazotized with sodium nitrite in dilute hydrochloric acid solution to obtain a diazonium salt solution;

[0007] (2) The diazonium salt solution was coupled with the acetic acid aqueous solution of N-ethyl-N-(2-hydroxyethyl)aniline, and the azo dye precursor containing two active hydroxyl groups was obtained after post-treatment.

[0008] (3) Dissolve the azo dye precursor in anhydrous N,N-dimethylformamide, and carry out an etherification reaction with epichlorohydrin in the presence of an alkaline catalyst. Then, add γ-aminopropyltriethoxysilane for silanization reaction, and then add diethyl 2-bromoethylphosphonate for quaternization reaction. After the reaction is completed, filter to obtain the dye intermediate solution.

[0009] (4) Add tetraethyl orthosilicate and tributyl borate to the dye intermediate solution and carry out a sol-gel reaction under acidic conditions to form a nano borosilicate shell and obtain a sol solution.

[0010] (5) Add anhydrous diethyl ether to the sol to precipitate the solid, and then filter, wash and dry to obtain cationic dye.

[0011] In this invention, the alkali resistance of cationic dyes is synergistically improved from the following two aspects: Firstly, under the action of a catalyst, the phenolic and alcoholic hydroxyl groups in the dye precursor molecule are converted into highly reactive oxygen anions, which then initiate a nucleophilic attack on epichlorohydrin to undergo an etherification reaction, successfully introducing epoxy active groups onto the dye molecule; then, the amino group of the aminosilane coupling agent undergoes a nucleophilic ring-opening addition to the epoxy group to form a stable dye-linker-silane molecular structure. The long-chain siloxane grafted to the periphery of the dye molecule has strong hydrophobicity and forms a dense physical barrier on the surface of the dye molecule, which can effectively block polar OH groups in the alkaline dyeing system. - The dye diffuses towards the azo chromophore at its core; simultaneously, the Si-C bond energy connecting the dye and silicon atoms is extremely high, and its chemical stability under alkaline conditions ensures that the protective layer will not break or peel off; furthermore, the Si-O-Si crosslinked network formed by the hydrolysis and condensation of the terminal silane groups in subsequent printing and dyeing applications further strengthens the steric hindrance effect and significantly reduces OH... - The probability of attacking the azo bond is increased, thus significantly improving the dye's alkali resistance. On the other hand, quaternization is used to introduce diethyl 2-bromoethylphosphonate into the dye structure. This reaction converts the amine group in the dye molecule into a more hydrophilic quaternary ammonium cationic group, ensuring the dye's water solubility and fiber uptake. Furthermore, the quaternary ammonium salt structure is chemically stable under alkaline conditions and will not undergo hydrolytic deactivation. In addition, the successfully introduced phosphonate functional group has extremely strong chelating ability, forming stable coordination complexes with calcium and magnesium ions commonly found in alkaline dyeing systems, constructing a second dense coordination protective layer on the dye molecule surface. This protective layer, together with the siloxane hydrophobic layer, forms a hydrophobic-coordination dual shielding system, synergistically preventing OH-. - Attacking the azo chromophore ultimately achieved the ultra-high stability of azo cationic dyes under extremely alkaline conditions.

[0012] Preferably, in step (1), the mass ratio of 2-amino-4-nitrophenol to sodium nitrite is 6:(2-4).

[0013] Preferably, in step (2), the mass ratio of 2-amino-4-nitrophenol to N-ethyl-N-(2-hydroxyethyl)aniline is 6:(8-10).

[0014] Preferably, in step (3), the mass ratio of the azo dye precursor to epichlorohydrin is 5:(6-7).

[0015] Preferably, in step (3), the mass ratio of the azo dye precursor to γ-aminopropyltriethoxysilane is 5:(7-8).

[0016] Preferably, in step (3), the mass ratio of the azo dye precursor to diethyl 2-bromoethylphosphonate is 5:(6-8).

[0017] Preferably, in step (4), the mass ratio of tetraethyl orthosilicate to tributyl borate is 5:(2-4).

[0018] In experiments, this invention discovered that phosphonate quaternary ammonium salt groups, due to their large size (high steric hindrance) and high polarity, exhibit strong steric hindrance when introduced into dye molecules and interacting with long silane chains. This physically "spreads out" the originally densely packed hydrophobic siloxane film, forming microscopic free volume voids. These voids readily become OH- in alkaline aqueous solutions. - The defective channels of directional penetration hinder the further improvement of the alkali resistance of cationic dyes. To address this technical problem, this invention utilizes the small molecular size and high reactivity of TEOS (tissue-derived phosphonate esters) with four functional groups, enabling it to penetrate deep into the tiny gaps between the large phosphonate ester groups and long silane chains. This allows it to act as a nano-filler, performing high-density in-situ cross-linking and physically repairing steric hindrance. Simultaneously, the tributyl borate molecule introduces Si-OB bonds with higher bond energy and shorter bond length, transforming the protective layer into a chemically resistant "borosilicate glass." Furthermore, the boron atoms have empty orbitals that can form intramolecular coordination locks with the phosphoryl oxygen in the phosphonate ester groups, significantly restricting the thermal motion of the large groups. Ultimately, this method grows a defect-free, high-density nano-borosilicate hybrid shell on the dye molecule surface in situ, completely blocking the penetration pathway of alkaline ions and achieving a significant improvement in alkali resistance.

[0019] A cationic dye is prepared by the method described above.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. A dense hydrophobic barrier is formed around the dye molecule through silanization, and phosphonate groups are simultaneously introduced to construct a coordination protective layer. The synergistic effect of these two methods effectively blocks the attack of hydroxide ions on the core azo chromophore in an alkaline environment, significantly improving the dye's alkali resistance.

[0022] 2. To address the issue that introducing large-volume phosphonate groups may disrupt the density of the siloxane layer, a novel approach was adopted: small-molecule tetraethyl orthosilicate (TEOS) and tributyl borate (TEOS) were used for in-situ interstitial filling and hybrid crosslinking. TEOS repaired microscopic defects, while boron formed high-energy Si-OB bonds and coordinated intramolecularly with the phosphonate, thereby constructing a defect-free, highly dense nano-borosilicate hybrid shell on the dye surface, further improving the dye's alkali resistance. Attached Figure Description

[0023] Figure 1 This is a low-magnification SEM image of the cationic dye prepared in Example 1 of the present invention.

[0024] Figure 2 This is a medium-magnification SEM image of the cationic dye prepared in Example 1 of the present invention.

[0025] Figure 3 This is a high-magnification SEM image of the cationic dye prepared in Example 1 of the present invention.

[0026] Figure 4 This is the XPS spectrum of the cationic dye prepared in Example 1 of the present invention.

[0027] Figure 5 The XRD pattern of the cationic dye prepared in Example 1 of this invention is shown. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] A method for preparing a cationic dye includes the following steps:

[0031] Step 1: Dissolve 12g of 2-amino-4-nitrophenol in 150mL of 6% hydrochloric acid solution and cool the system to 5℃; add 7g of sodium nitrite to 50mL of deionized water and stir to dissolve, obtaining sodium nitrite solution; under a stirring rate of 350r / min and with the temperature strictly controlled below 5℃, add the sodium nitrite solution dropwise to the above system, and continue the reaction for 2h after the addition is complete, then add 0.5g of aminosulfonic acid to obtain diazonium salt solution.

[0032] Step 2: Dissolve 19g of N-ethyl-N-(2-hydroxyethyl)aniline in 200mL of 10% acetic acid aqueous solution, add saturated sodium acetate solution to adjust the pH to 4.5, cool to 5℃, and slowly add diazonium salt solution dropwise while stirring at 250r / min. During the dropwise addition, continuously add sodium acetate to maintain the pH at 4.5. After the dropwise addition is complete, allow the temperature to rise naturally to room temperature and react for 4h. Filter the solution, wash the filter cake with deionized water until neutral, and then dry it in a vacuum oven at 60℃ for 12h to constant weight. Grind the powder to obtain dark red azo dye precursor powder.

[0033] Step 3: Dissolve 25g of azo dye precursor powder in 350mL of anhydrous N,N-dimethylformamide, add 12g of finely ground anhydrous potassium carbonate and 0.5g of TBAB; heat to 85℃, add 34g of epichlorohydrin (ECH) dropwise, react for 4h, and remove excess ECH by vacuum distillation; then add 39g of γ-aminopropyltriethoxysilane, react at 90℃ for 2h to complete silane grafting, then add 38g of diethyl 2-bromoethylphosphonate and 1.5g of potassium iodide, heat to 105℃ and reflux at 500r / min for 14h to quaternize; after the reaction is complete, cool to room temperature and filter precisely using a 0.45μm filter membrane to obtain the dye intermediate solution.

[0034] Step 4: Cool the dye intermediate solution to 60℃, add 5.0g of tetraethyl orthosilicate (TEOS) and 3.5g of tributyl borate, and prepare the hydrolysis initiation solution (dissolve 2.0mL of deionized water in 10mL of DMF, and adjust the pH to 4-5 with glacial acetic acid); under vigorous stirring at 400r / min, add the initiation solution dropwise to the dye solution very slowly. After the addition is complete, maintain a constant temperature of 60℃ for 6h to obtain the sol solution.

[0035] Step 5: Cool the sol solution to room temperature and slowly add it dropwise to 2000 mL of vigorously stirred anhydrous diethyl ether. The product quickly precipitates as a colloidal powder, and the solid is collected by filtration. The filter cake is washed twice with a small amount of anhydrous diethyl ether and finally placed in a vacuum drying oven and dried at 45℃ and -0.09 MPa for 10 h to obtain the finished cationic dye.

[0036] Example 2

[0037] A method for preparing a cationic dye includes the following steps:

[0038] Step 1: Dissolve 12g of 2-amino-4-nitrophenol in 150mL of 6% hydrochloric acid solution and cool the system to 5℃; add 5g of sodium nitrite to 50mL of deionized water and stir to dissolve, obtaining sodium nitrite solution; under a stirring rate of 350r / min and with the temperature strictly controlled below 5℃, add the sodium nitrite solution dropwise to the above system, and continue the reaction for 2h after the addition is complete, then add 0.5g of aminosulfonic acid to obtain diazonium salt solution.

[0039] Step 2: Dissolve 17g of N-ethyl-N-(2-hydroxyethyl)aniline in 200mL of 10% acetic acid aqueous solution, add saturated sodium acetate solution to adjust the pH to 4.5, cool to 5℃, and slowly add diazonium salt solution dropwise while stirring at 250r / min. During the dropwise addition, continuously add sodium acetate to maintain the pH at 4.5. After the dropwise addition is complete, allow the temperature to rise naturally to room temperature and react for 4h. Filter the solution, wash the filter cake with deionized water until neutral, and then dry it in a vacuum oven at 60℃ for 12h to constant weight. Grind the powder to obtain dark red azo dye precursor powder.

[0040] Step 3: Dissolve 25g of azo dye precursor powder in 350mL of anhydrous N,N-dimethylformamide, add 12g of finely ground anhydrous potassium carbonate and 0.5g of TBAB; heat to 85℃, add 32g of epichlorohydrin (ECH) dropwise, react for 4h, and remove excess ECH by vacuum distillation; then add 36g of γ-aminopropyltriethoxysilane, react at 90℃ for 2h to complete silane grafting, then add 33g of diethyl 2-bromoethylphosphonate and 1.5g of potassium iodide, heat to 105℃ and reflux at 500r / min for 14h to quaternize; after the reaction is complete, cool to room temperature and filter precisely using a 0.45μm filter membrane to obtain the dye intermediate solution.

[0041] Step 4: Cool the dye intermediate solution to 60℃, add 5.0g of tetraethyl orthosilicate (TEOS) and 2.5g of tributyl borate, and prepare the hydrolysis initiation solution (dissolve 2.0mL of deionized water in 10mL of DMF, and adjust the pH to 4-5 with glacial acetic acid); under vigorous stirring at 400r / min, add the initiation solution dropwise to the dye solution very slowly. After the addition is complete, maintain a constant temperature of 60℃ for 6h to obtain the sol solution.

[0042] Step 5: Cool the sol solution to room temperature and slowly add it dropwise to 2000 mL of vigorously stirred anhydrous diethyl ether. The product quickly precipitates as a colloidal powder, and the solid is collected by filtration. The filter cake is washed twice with a small amount of anhydrous diethyl ether and finally placed in a vacuum drying oven and dried at 45℃ and -0.09 MPa for 10 h to obtain the finished cationic dye.

[0043] Example 3

[0044] A method for preparing a cationic dye includes the following steps:

[0045] Step 1: Dissolve 12g of 2-amino-4-nitrophenol in 150mL of 6% hydrochloric acid solution and cool the system to 5℃; add 6g of sodium nitrite to 50mL of deionized water and stir to dissolve, obtaining sodium nitrite solution; under a stirring rate of 350r / min and with the temperature strictly controlled below 5℃, add the sodium nitrite solution dropwise to the above system, and continue the reaction for 2h after the addition is complete, then add 0.5g of aminosulfonic acid to obtain diazonium salt solution.

[0046] Step 2: Dissolve 18g of N-ethyl-N-(2-hydroxyethyl)aniline in 200mL of 10% acetic acid aqueous solution, add saturated sodium acetate solution to adjust the pH to 4.5, cool to 5℃, and slowly add diazonium salt solution dropwise while stirring at 250r / min. During the dropwise addition, continuously add sodium acetate to maintain the pH at 4.5. After the dropwise addition is complete, allow the temperature to rise naturally to room temperature and react for 4h. Filter the solution, wash the filter cake with deionized water until neutral, and then dry it in a vacuum oven at 60℃ for 12h to constant weight. Grind the powder to obtain dark red azo dye precursor powder.

[0047] Step 3: Dissolve 25g of azo dye precursor powder in 350mL of anhydrous N,N-dimethylformamide, add 12g of finely ground anhydrous potassium carbonate and 0.5g of TBAB; heat to 85℃, add 33g of epichlorohydrin (ECH) dropwise, react for 4h, and remove excess ECH by vacuum distillation; then add 37g of γ-aminopropyltriethoxysilane, react at 90℃ for 2h to complete silane grafting, then add 35g of diethyl 2-bromoethylphosphonate and 1.5g of potassium iodide, heat to 105℃ and reflux at 500r / min for 14h to quaternize; after the reaction is complete, cool to room temperature and filter precisely using a 0.45μm filter membrane to obtain the dye intermediate solution.

[0048] Step 4: Cool the dye intermediate solution to 60℃, add 5.0g of tetraethyl orthosilicate (TEOS) and 3g of tributyl borate, and prepare a hydrolysis initiation solution (dissolve 2.0mL of deionized water in 10mL of DMF, and adjust the pH to 4-5 with glacial acetic acid); under vigorous stirring at 400r / min, add the initiation solution dropwise to the dye solution very slowly. After the addition is complete, maintain a constant temperature of 60℃ for 6h to obtain a sol solution.

[0049] Step 5: Cool the sol solution to room temperature and slowly add it dropwise to 2000 mL of vigorously stirred anhydrous diethyl ether. The product quickly precipitates as a colloidal powder, and the solid is collected by filtration. The filter cake is washed twice with a small amount of anhydrous diethyl ether and finally placed in a vacuum drying oven and dried at 45℃ and -0.09 MPa for 10 h to obtain the finished cationic dye.

[0050] Example 4

[0051] A method for preparing a cationic dye includes the following steps:

[0052] Step 1: Dissolve 12g of 2-amino-4-nitrophenol in 150mL of 6% hydrochloric acid solution and cool the system to 5℃; add 8g of sodium nitrite to 50mL of deionized water and stir to dissolve, obtaining sodium nitrite solution; under a stirring rate of 350r / min and with the temperature strictly controlled below 5℃, add the sodium nitrite solution dropwise to the above system, and continue the reaction for 2h after the addition is complete, then add 0.5g of aminosulfonic acid to obtain diazonium salt solution.

[0053] Step 2: Dissolve 20g of N-ethyl-N-(2-hydroxyethyl)aniline in 200mL of 10% acetic acid aqueous solution, add saturated sodium acetate solution to adjust the pH to 4.5, cool to 5℃, and slowly add diazonium salt solution dropwise while stirring at 250r / min. During the dropwise addition, continuously add sodium acetate to maintain the pH at 4.5. After the dropwise addition is complete, allow the temperature to rise naturally to room temperature and react for 4h. Filter the solution, wash the filter cake with deionized water until neutral, and then dry it in a vacuum oven at 60℃ for 12h to constant weight. Grind the powder to obtain dark red azo dye precursor powder.

[0054] Step 3: Dissolve 25g of azo dye precursor powder in 350mL of anhydrous N,N-dimethylformamide, add 12g of finely ground anhydrous potassium carbonate and 0.5g of TBAB; heat to 85℃, add 35g of epichlorohydrin (ECH) dropwise, react for 4h, and remove excess ECH by vacuum distillation; then add 40g of γ-aminopropyltriethoxysilane, react at 90℃ for 2h to complete silane grafting, then add 40g of diethyl 2-bromoethylphosphonate and 1.5g of potassium iodide, heat to 105℃ and reflux at 500r / min for 14h to quaternize; after the reaction is complete, cool to room temperature and filter precisely using a 0.45μm filter membrane to obtain the dye intermediate solution.

[0055] Step 4: Cool the dye intermediate solution to 60℃, add 5.0g of tetraethyl orthosilicate (TEOS) and 4g of tributyl borate, and prepare the hydrolysis initiation solution (dissolve 2.0mL of deionized water in 10mL of DMF, and adjust the pH to 4-5 with glacial acetic acid); under vigorous stirring at 400r / min, add the initiation solution dropwise to the dye solution very slowly. After the addition is complete, maintain a constant temperature of 60℃ for 6h to obtain the sol solution.

[0056] Step 5: Cool the sol solution to room temperature and slowly add it dropwise to 2000 mL of vigorously stirred anhydrous diethyl ether. The product quickly precipitates as a colloidal powder, and the solid is collected by filtration. The filter cake is washed twice with a small amount of anhydrous diethyl ether and finally placed in a vacuum drying oven and dried at 45℃ and -0.09 MPa for 10 h to obtain the finished cationic dye.

[0057] Example 5

[0058] A method for preparing a cationic dye includes the following steps:

[0059] Step 1: Dissolve 12g of 2-amino-4-nitrophenol in 150mL of 6% hydrochloric acid solution and cool the system to 5℃; add 4g of sodium nitrite to 50mL of deionized water and stir to dissolve, obtaining sodium nitrite solution; under a stirring rate of 350r / min and with the temperature strictly controlled below 5℃, add the sodium nitrite solution dropwise to the above system, and continue the reaction for 2h after the addition is complete, then add 0.5g of aminosulfonic acid to obtain diazonium salt solution.

[0060] Step 2: Dissolve 16g of N-ethyl-N-(2-hydroxyethyl)aniline in 200mL of 10% acetic acid aqueous solution, add saturated sodium acetate solution to adjust the pH to 4.5, cool to 5℃, and slowly add diazonium salt solution dropwise while stirring at 250r / min. During the dropwise addition, continuously add sodium acetate to maintain the pH at 4.5. After the dropwise addition is complete, allow the temperature to rise naturally to room temperature and react for 4h. Filter the solution, wash the filter cake with deionized water until neutral, and then dry it in a vacuum oven at 60℃ for 12h to constant weight. Grind the powder to obtain dark red azo dye precursor powder.

[0061] Step 3: Dissolve 25g of azo dye precursor powder in 350mL of anhydrous N,N-dimethylformamide, add 12g of finely ground anhydrous potassium carbonate and 0.5g of TBAB; heat to 85℃, add 30g of epichlorohydrin (ECH) dropwise, react for 4h, and remove excess ECH by vacuum distillation; then add 35g of γ-aminopropyltriethoxysilane, react at 90℃ for 2h to complete silane grafting, then add 30g of diethyl 2-bromoethylphosphonate and 1.5g of potassium iodide, heat to 105℃ and reflux at 500r / min for 14h to quaternize; after the reaction is complete, cool to room temperature and filter precisely using a 0.45μm filter membrane to obtain the dye intermediate solution.

[0062] Step 4: Cool the dye intermediate solution to 60℃, add 5.0g of tetraethyl orthosilicate (TEOS) and 2g of tributyl borate, and prepare a hydrolysis initiation solution (dissolve 2.0mL of deionized water in 10mL of DMF, and adjust the pH to 4-5 with glacial acetic acid); under vigorous stirring at 400r / min, add the initiation solution dropwise to the dye solution very slowly. After the addition is complete, maintain a constant temperature of 60℃ for 6h to obtain a sol solution.

[0063] Step 5: Cool the sol solution to room temperature and slowly add it dropwise to 2000 mL of vigorously stirred anhydrous diethyl ether. The product quickly precipitates as a colloidal powder, and the solid is collected by filtration. The filter cake is washed twice with a small amount of anhydrous diethyl ether and finally placed in a vacuum drying oven and dried at 45℃ and -0.09 MPa for 10 h to obtain the finished cationic dye.

[0064] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that γ-aminopropyltriethoxysilane is not added in step 3.

[0065] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that diethyl 2-bromoethylphosphonate is not added in step 3.

[0066] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that tetraethyl orthosilicate and tributyl borate are not added in step 4.

[0067] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that tetraethyl orthosilicate is not added in step 4.

[0068] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that tributyl borate is not added in step 4.

[0069] Performance testing:

[0070] 1. Dye Uptake Test: The dye uptake rate was determined using spectrophotometry. 0.5g of acrylic fabric was accurately weighed, and a dyeing solution with a dye concentration of 2% (owf) and a liquor ratio of 1:50 was prepared, adjusting the pH to 4.5. The fabric was immersed in the dye bath, and the temperature was increased to 98℃ at a rate of 1℃ / min, and dyeing was maintained at this temperature for 60 min. After dyeing, the dye bath and washing solution before and after dyeing were collected, and the absorbance was measured at the maximum absorption wavelength using a UV-Vis spectrophotometer. The dye uptake rate was calculated using the formula: E = (1 - A1 / A0) × 100%, where E is the dye uptake rate, A0 is the absorbance of the dye bath before dyeing, and A1 is the absorbance of the mixed dyeing residue and washing solution. The test results are shown in Table 1.

[0071] 2. Alkali Resistance Stability Test: Simulating high-temperature alkaline conditions, the color stability of the dye under extreme alkaline conditions was tested. Two portions of the dyed and dried fabric were cut; one portion served as a standard sample; the other portion was immersed in an alkaline aqueous solution with pH=12 (adjusted with NaOH) and a temperature of 98℃, at a liquor ratio of 1:50, for 60 minutes. After treatment, the fabric was washed and dried. The color difference (ΔE) and color intensity retention rate (K / S retention rate) of the fabric before and after treatment were measured using a computer colorimeter. The smaller the ΔE and the higher the retention rate, the better the alkali resistance stability of the dye and the less likely the structure is to be damaged. The test results are shown in Table 1.

[0072] 3. The color fastness to washing was tested according to the national standard GB / T 3921-2008 "Textiles - Tests for Color Fastness - Color Fastness to Washing". The dyed fabric was sewn to a multi-fiber lining fabric and washed under the specified washing conditions (40℃, 30 min). After washing and drying, the color change grade of the sample and the staining grade of the lining fabric were assessed using a gray scale under a standard light source. The test results are shown in Table 1.

[0073] 4. The color fastness to rubbing was tested according to the national standard GB / T 3920-2008 "Textiles - Tests for Color Fastness - Color Fastness to Rubbing". A color fastness to rubbing tester was used to conduct both dry and wet rubbing tests, and the staining grade of the rubbing fabric was assessed using a gray scale. The test results are shown in Table 1.

[0074] 5. The test for lightfastness was conducted according to the national standard GB / T 8427-2008 "Textiles - Tests for Colorfastness to Artificial Light: Xenon Arc". The sample and a blue wool standard sample were simultaneously exposed to a xenon arc lamp until the blue wool standard sample reached the specified color change grade. The lightfastness grade of the sample was then compared and evaluated. The test results are shown in Table 1.

[0075] Table 1:

[0076] Dyeing rate (%) Color difference (ΔE) K / S retention rate (%) Wash fastness (grade) - color change / staining Color fastness to rubbing (grade) dry / wet rubbing Colorfastness to sunlight (grade) Example 1 98.2 0.52 96.7 4-5 / 4-5 4-5 / 4-5 6 Example 2 97.8 0.65 95.6 4-5 / 4-5 4-5 / 4-5 5-6 Example 3 98.5 0.48 97.2 5 / 5 5 / 4-5 6 Example 4 98.1 0.54 96.5 4-5 / 5 4-5 / 4-5 6 Example 5 97.5 0.61 95.8 4-5 / 4-5 4-5 / 4-5 5-6 Comparative Example 1 96.3 5.82 62.4 3 / 3 3 / 2-3 3 Comparative Example 2 65.2 3.44 78.1 2-3 / 3 3 / 3 4 Comparative Example 3 97.2 2.15 85.6 4 / 4 4 / 3-4 4-5 Comparative Example 4 96.8 1.85 88.2 4 / 4 4 / 4 5 Comparative Example 5 97.0 1.63 89.5 4 / 4-5 4 / 4 5

[0077] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a cationic dye, characterized in that, Includes the following steps: (1) 2-Amino-4-nitrophenol was diazotized with sodium nitrite in dilute hydrochloric acid solution to obtain a diazonium salt solution; (2) The diazonium salt solution was coupled with the acetic acid aqueous solution of N-ethyl-N-(2-hydroxyethyl)aniline, and the azo dye precursor containing two active hydroxyl groups was obtained after post-treatment. (3) Dissolve the azo dye precursor in anhydrous N,N-dimethylformamide, and carry out an etherification reaction with epichlorohydrin in the presence of an alkaline catalyst. Then, add γ-aminopropyltriethoxysilane for silanization reaction, and then add diethyl 2-bromoethylphosphonate for quaternization reaction. After the reaction is completed, filter to obtain the dye intermediate solution. (4) Add tetraethyl orthosilicate and tributyl borate to the dye intermediate solution and carry out a sol-gel reaction under acidic conditions to form a nano borosilicate shell and obtain a sol solution. (5) Add anhydrous diethyl ether to the sol to precipitate the solid, and then filter, wash and dry to obtain cationic dye.

2. The method for preparing a cationic dye according to claim 1, characterized in that, In step (1), the mass ratio of 2-amino-4-nitrophenol to sodium nitrite is 6:(2-4).

3. The method for preparing a cationic dye according to claim 1, characterized in that, In step (2), the mass ratio of 2-amino-4-nitrophenol to N-ethyl-N-(2-hydroxyethyl)aniline is 6:(8-10).

4. The method for preparing a cationic dye according to claim 1, characterized in that, In step (3), the mass ratio of the azo dye precursor to epichlorohydrin is 5:(6-7).

5. The method for preparing a cationic dye according to claim 1, characterized in that, In step (3), the mass ratio of the azo dye precursor to γ-aminopropyltriethoxysilane is 5:(7-8).

6. The method for preparing a cationic dye according to claim 1, characterized in that, In step (3), the mass ratio of the azo dye precursor to diethyl 2-bromoethylphosphonate is 5:(6-8).

7. The method for preparing a cationic dye according to claim 1, characterized in that, In step (4), the mass ratio of tetraethyl orthosilicate to tributyl borate is 5:(2-4).

8. A cationic dye, characterized in that, It is prepared by the method described in any one of claims 1 to 7.

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