Flame-retardant indigo blue composite dye and preparation method thereof
By preparing flame-retardant indigo composite dyes, the flame-retardant barrier is formed by phosphite groups and benzotriazole structures, and a conductive layer is formed by quaternary ammonium salt cations. This solves the problems of dispersion stability and antistatic properties of indigo dyes, and improves the flame retardancy, antistatic properties and ultraviolet absorption performance of dyed fabrics.
Patent Information
- Application Number
- CN202511474742.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-15
- Publication Date
- 2026-02-03
AI Technical Summary
Indigo dye has poor dispersion stability in dye liquor, resulting in uneven dyeing. Furthermore, cotton fabrics are flammable and prone to static electricity accumulation. Traditional modification methods cannot effectively solve the problems of dispersion and flame retardancy, increasing costs and affecting the dyeing effect.
By preparing flame-retardant indigo composite dyes, a flame-retardant barrier is formed using phosphite groups and benzotriazole structures, and a conductive layer is formed using quaternary ammonium salt cations, which enhances the dispersion stability and antistatic properties of the indigo dyes. Furthermore, the synergist is stabilized through π-π stacking and hydrogen bond networks, thereby improving the ultraviolet absorption performance of the dyes.
It achieves uniform dispersion of indigo dye on fabrics, improves flame retardant properties, antistatic properties and ultraviolet absorption properties, and enhances the quality and safety of dyed fabrics.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of dyes, and in particular relates to a flame-retardant indigo composite dye and a preparation method thereof. BACKGROUND
[0002] Indigo is a classic vat dye with a history of thousands of years of application, and is widely used due to its unique color. However, with the increasing requirements of the modern textile industry for functionality, ecological friendliness and processing efficiency, the application of indigo is facing challenges.
[0003] Indigo has many defects due to its molecular structure and application characteristics. For example, the indigo molecule contains multiple conjugated aromatic rings, which is prone to molecular aggregation, forming aggregates with uneven particle sizes, resulting in poor dispersion stability in the dyeing solution, causing color spots and color flowers on the dyed fabric, leading to uneven dyeing, affecting product quality, and increasing the difficulty and cost of production management. Traditional indigo dyed fabrics only have basic coloring function, and have obvious short board in the flame-retardant functional index. In addition, cotton fabric dyed with indigo is a flammable material, and the fiber surface lacks conductive groups, which is prone to static electricity accumulation, and long-term use poses a risk of skin damage. Traditional modification methods usually add a large amount of traditional dispersants, which mainly work through electrostatic repulsion, and cannot fundamentally solve the dispersion problem. And excessive addition not only increases the cost, but also may affect the dye uptake and dyeing fastness of the dye.
[0004] Based on this, the present application provides a preparation method of a flame-retardant indigo composite dye. SUMMARY
[0005] The present application aims to provide a flame-retardant indigo composite dye and a preparation method thereof, which solves the problems mentioned in the background.
[0006] The purpose of the present application can be achieved by the following technical solutions: A preparation method of a flame-retardant indigo composite dye, comprising the following steps: Step 1: 4-nitropyridine, halogenated alcohol and acetonitrile are added to a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 60-80℃ for 16-24h. After the reaction is completed, the reaction solution is cooled to room temperature, then poured into petroleum ether for precipitation, and the solid is filtered and dried to obtain an antistatic monomer; The product is washed with petroleum ether, filtered, and the solid is dried and rotary evaporated to obtain the antistatic monomer; Second step: anti-static monomer, phosphorus trichloride, acid binding agent, anhydrous magnesium chloride and acetonitrile are added into a three-necked flask, a condenser tube and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 70-80℃ for 2-4h, then the temperature is increased to 80-90℃, and the reaction is carried out for 18-22h, after the reaction is completed, the reaction solution is poured into deionized water to precipitate, then the solid is filtered and washed with deionized water and dried to obtain the flame retardant; The product is transferred to water for quenching, then extracted with dichloromethane and water respectively, and the organic phase is reserved, then washed with saturated brine and dried, and then eluted by silica gel column chromatography to obtain the flame retardant; Third step: the flame retardant, hydroxybenzotriazole, potassium carbonate and N,N-dimethylformamide are added into a three-necked flask, a condenser tube and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 70-90℃ for 3-5h, after the reaction is completed, the reaction solution is poured into deionized water to precipitate, then the solid is filtered and washed with deionized water and dried, and then purified by silica gel column chromatography to obtain the synergist; The reaction solution is cooled to room temperature, then transferred to water, and the solid is filtered after precipitation, then the solid is filtered, washed with n-hexane and saturated brine and dried, and then eluted by silica gel column chromatography to obtain the synergist; Fourth step: indigo, synergist, reducing agent and dyeing accelerator are respectively added into a ball mill and ball milled for 2-4h, then the powders are premixed, and the mixed powders are further ball milled for 2-4h by the ball mill, after the ball milling is completed, water, surfactant and hygroscopic agent are added into the grinding tank for wet milling, after the wet milling is completed, the sample is dried and ground to obtain the indigo composite dye.
[0007] Further, the structural general formula of the halogenated alcohol in the first step is , wherein n is a natural number of 2≤n≤6, and X is one of chlorine and bromine.
[0008] Further, the mass fraction ratio of 4-nitropyridine, halogenated alcohol and acetonitrile in the first step is 21-25:16-27.4:160-200.
[0009] Further, the acid binding agent in the second step is one of triethylamine, pyridine and N,N-diisopropyl ethylamine.
[0010] Further, the mass fraction ratio of anti-static monomer, phosphorus trichloride, acid binding agent, anhydrous magnesium chloride and acetonitrile in the second step is 78-91:17-19:40-46:2-5:560-600.
[0011] Further, the mass fraction ratio of flame retardant, hydroxybenzotriazole, potassium carbonate and N,N-dimethylformamide in the third step is 52-62:38-44:40-50:400-450.
[0012] Further, the reducing agent in the fourth step is at least one of sodium sulfide, sodium sulfite and sodium hyposulfite.
[0013] Further, the dyeing promoter in the fourth step is at least one of sodium carbonate, sodium chloride and sodium sulfate.
[0014] Further, the surface active agent in the fourth step is at least one of Tween 60, Tween 65 and Tween 80.
[0015] Further, the moisture absorbent in the fourth step is at least one of ethanol, ethylene glycol and propylene glycol.
[0016] Further, the mass ratio of indigo, the synergist, the reducing agent, the dyeing promoter, water, the surface active agent and the moisture absorbent in the fourth step is 100-110: 50-60: 50-55: 50-60: 250-280: 15-16: 20-22.
[0017] A flame-retardant indigo composite dye is prepared by any of the above preparation steps.
[0018] Advantages of the present application: The phosphite group in the synergist makes the fabric dyed with the indigo composite dye release phosphorus free radicals when heated, inhibits the combustion chain reaction, and prevents the spread of flames; at the same time, it can promote the carbonization of the combustible surface and form a dense protective carbon layer to block heat and oxygen, achieving a flame-retardant effect. In addition, the nitrogen element in the benzotriazole structure in the synergist can act as a foaming agent to expand the carbon layer, and the two work together to form a strong heat-insulating and flame-retardant barrier, giving the indigo dye good flame-retardant properties, making the dyed fabric more in line with fire safety requirements, and being applicable to more fields.
[0019] The quaternary ammonium salt ion in the antistatic monomer obtained by the quaternary ammonium salt reaction can form a conductive layer on the surface of the fabric to dissipate static charges, and can also reduce the surface resistance through an ionic conduction mechanism to prevent the accumulation of static electricity, achieving an antistatic effect on the dyed fabric; in addition, the quaternary ammonium salt ion has a positive charge, while indigo has a negative ion property during the dyeing process and in an aqueous solution, the two will attract each other through electrostatic attraction, making the dye molecules more firmly attached to the surface or inside of the fabric, reducing the shedding of the dye during washing and other processes, and achieving a certain fixing effect.
[0020] The hydroxybenzotriazole of the present application is subjected to nucleophilic substitution reaction with the flame retardant, and a new conjugated pi electron system is formed with the original pyridine structure in the flame retardant, thereby synergistically expanding the ultraviolet absorption range of the composite dye, enhancing the ultraviolet absorption performance of the dyed fabric, and effectively relieving the fading caused by the loss of indigo after absorbing ultraviolet rays. In addition, the pi electron system of benzotriazole can effectively form pi-pi stacking with the conjugated system of indigo, and at the same time, the benzotriazole structure can also form a hydrogen bond network with the indigo molecules. The combination of the two interactions stably fixes the synergist around the indigo molecules.
[0021] The spatial structure of the phosphite group in the synergist is trigonal pyramidal, so that the substituted groups are not in one plane, and the synergist as a whole forms a three-dimensional spatial structure. This structure can effectively prevent the formation of indigo aggregates, so that the indigo has good dispersion stability. The well-dispersed indigo can be more uniformly adsorbed and penetrated into the interior of the fiber, avoiding problems such as color spots and color flowers, and improving product quality. DETAILED DESCRIPTION
[0022] The technical solutions of the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.
[0023] Among them, all raw materials of the present application are not particularly limited in source, and can be purchased on the market or prepared according to the conventional method well known to those skilled in the art. Example 1
[0024] A preparation method of a flame-retardant indigo composite dye comprises the following steps: First step, 21g of 4-nitropyridine, 16g of 2-chloroethanol and 160g of acetonitrile are added to a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 60℃ for 24h. After the reaction is completed, the product is cooled to room temperature, washed with petroleum ether, filtered, and then the obtained solid is dried and rotary evaporated to obtain an antistatic monomer; Second step, 78g of the antistatic monomer, 17g of phosphorus trichloride, 40g of triethylamine, 2g of anhydrous magnesium chloride and 560g of acetonitrile are added to a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 70℃ for 4h, and then the temperature is raised to 80℃ and the reaction is carried out for 22h. After the reaction is completed, the product is transferred to water for quenching, and then extracted with dichloromethane and water respectively, and the organic phase is reserved. Then, the organic phase is washed with saturated brine and dried, and then eluted by silica gel column chromatography to obtain a flame retardant. Third step, 52g flame retardant, 38g hydroxybenzotriazole, 40g potassium carbonate and 400g N,N-dimethylformamide are added to a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 70°C for 5h. After the reaction is completed, the reaction solution is cooled to room temperature, and then transferred to water. After the solid is precipitated, it is filtered. The obtained solid is washed with n-hexane and saturated brine respectively, and then dried. After that, the product is eluted by silica gel column chromatography to obtain a synergist. Fourth step, 100g indigo, 50g synergist, 50g sodium sulfide and 50g sodium carbonate are respectively added to a ball mill and ball milled for 4h. Then the mixed powder is pre-mixed, and then the mixed powder is further ball milled for 4h by using a ball mill. After the ball milling is completed, 250g water, 15g Tween 60 and 20g ethanol are added to the grinding tank for wet grinding. After the wet grinding is completed, the sample is dried and ground to obtain an indigo composite dye.
[0025] A flame-retardant indigo composite dye is prepared by the above preparation steps. Example 2
[0026] A preparation method of a flame-retardant indigo composite dye comprises the following steps: First step, 23g 4-nitropyridine, 21.8g 4-bromo-1-butanol and 180g acetonitrile are added to a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 70°C for 20h. After the reaction is completed, the product is cooled to room temperature, washed with petroleum ether, filtered, dried and rotary evaporated to obtain an antistatic monomer. Second step, 84.5g antistatic monomer, 18g phosphorus trichloride, 43g pyridine, 3.5g anhydrous magnesium chloride and 580g acetonitrile are added to a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 75°C for 3h. Then the temperature is raised to 85°C, and the reaction is carried out for 20h. After the reaction is completed, the product is transferred to water for quenching, and then extracted with dichloromethane and water respectively. The organic phase is retained, washed with saturated brine and dried. After that, the product is eluted by silica gel column chromatography to obtain a flame retardant. Third step, 52g flame retardant, 38g hydroxybenzotriazole, 40g potassium carbonate and 400g N,N-dimethylformamide are added to a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 70°C for 5h. After the reaction is completed, the reaction solution is cooled to room temperature, and then transferred to water. After the solid is precipitated, it is filtered. The obtained solid is washed with n-hexane and saturated brine respectively, and then dried. After that, the product is eluted by silica gel column chromatography to obtain a synergist. Fourth step, 105 g of indigo, 55 g of synergist, 52.5 g of sodium sulfite and 55 g of sodium chloride are respectively added to the ball mill and ball milled for 3 h, then the powder is premixed, and then the mixed powder is continuously ball milled for 3 h with the ball mill. After the ball milling is completed, 265 g of water, 15.5 g of Tween 65 and 21 g of ethylene glycol are added to the grinding tank for wet grinding. After the wet grinding is completed, the sample is dried and ground, and an indigo composite dye is obtained.
[0027] A flame-retardant indigo composite dye is prepared by the above preparation steps. Example 3
[0028] A method for preparing a flame-retardant indigo composite dye, comprising the following steps: First step, 25 g of 4-nitropyridine, 27.4 g of 6-chloro-1-hexanol and 200 g of acetonitrile are added to a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 80℃ for 16 h. After the reaction is completed, it is cooled to room temperature, the product is washed with petroleum ether, filtered, the solid is filtered out, then the obtained solid is dried and rotary evaporated to obtain an antistatic monomer. Second step, 91 g of antistatic monomer, 19 g of phosphorus trichloride, 46 g of N,N-diisopropylethylamine, 5 g of anhydrous magnesium chloride and 600 g of acetonitrile are added to a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 80℃ for 2 h. Then the temperature is raised to 90℃ and the reaction is carried out for 18 h. After the reaction is completed, the product is transferred to water for quenching, then extracted with dichloromethane and water respectively and the organic phase is reserved. Then the organic phase is washed with saturated brine and dried, and then eluted by silica gel column chromatography to obtain a flame retardant. Third step, 62 g of flame retardant, 44 g of hydroxybenzotriazole, 50 g of potassium carbonate and 450 g of N,N-dimethylformamide are added to a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and the reaction is carried out at 90℃ for 3 h. After the reaction is completed, the reaction liquid is cooled to room temperature, then transferred to water, the solid is filtered out, then washed with n-hexane and saturated brine respectively and dried, and then eluted by silica gel column chromatography to obtain a synergist. Fourth step, 110 g of indigo, 60 g of synergist, 55 g of sodium dithionite and 60 g of sodium sulfate are respectively added to the ball mill and ball milled for 4 h. Then the powder is premixed, and then the mixed powder is continuously ball milled for 4 h with the ball mill. After the ball milling is completed, 280 g of water, 16 g of Tween 80 and 22 g of propylene glycol are added to the grinding tank for wet grinding. After the wet grinding is completed, the sample is dried and ground, and an indigo composite dye is obtained.
[0029] A flame-retardant indigo composite dye is prepared by the above preparation steps.
[0030] Comparative Example 1 The difference between this comparative example and Example 2 is that no synergist is added, and the rest of the raw materials and preparation steps remain unchanged.
[0031] Experimental Example 1 The indigo composite dyes in Examples 1-3 and Comparative Example 1 were dyed on cotton fabric by D5 medium dyeing method, with the weight ratio of indigo composite dye to dry cotton being 1:2 and the bath ratio being 1:30. The performance of the cotton fabric after being dyed with indigo composite dye was tested, the limited oxygen index IOR of each group of cotton fabric after being dyed with indigo composite dye was tested according to GB / T5454-1997 "Textile Burning Performance Test", the surface resistivity of each group of cotton fabric after being dyed with indigo composite dye was tested according to GB / T12703.1-2021 "Textile Static Performance Test Method", the color fastness grade of each group of cotton fabric after being dyed with indigo composite dye was tested according to GB / T23976.1-2009 "Textile Color Fastness Test", the ultraviolet protection factor of each group of cotton fabric after being dyed with indigo composite dye was tested according to GB / T18830-2009 "Evaluation of Textile Anti-Ultraviolet Performance", and the pure cotton fabric without being dyed with indigo composite dye was used as a blank control. The test results are shown in Table 1.
[0032] Table 1
[0033] As can be seen from Table 1, compared with Comparative Example 1, Examples 1-3 have higher limited oxygen index, surface resistivity, color fastness grade and ultraviolet protection factor, indicating that the flame retardant performance, antistatic performance, color fixing performance and ultraviolet resistance of the cotton fabric dyed with indigo composite dye in Examples 1-3 are better than those of Comparative Example 1. Combined with Comparative Example 1, it can be seen that the addition of synergist can effectively improve the flame retardant performance, antistatic performance, color fixing performance and ultraviolet resistance of the cotton fabric dyed with indigo composite dye.
[0034] Experimental Example 2 The indigo composite dyes in Examples 1-3 and Comparative Example 1 were tested for performance. Each group of cable composite dye was mixed with 50 mL of distilled water, and after standing for 30 days, the layering of the suspension was observed. The less the suspension was layered, the better the dispersion stability was. The test results are shown in Table 2.
[0035] Table 2
[0036] As can be seen from Table 2, compared with Comparative Example 1, Examples 1-3 have better dispersion stability, indicating that the addition of synergist can effectively improve the dispersion stability of indigo composite dye.
[0037] The above description of the examples is merely intended to help understand the method of the present application and its core idea. Various modifications to these examples will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other examples without departing from the spirit or scope of the present application. Thus, the present application is not to be limited to the examples shown herein but is to accord with the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A process for the production of a flame-retardant indigo complex dye, characterized in that The method comprises the following steps: Preparation of the synergist: an antistatic monomer is obtained by quaternary ammonium salt reaction of 4-nitropyridine and halogenated alcohol, a flame retardant is obtained by nucleophilic substitution reaction of the antistatic monomer and phosphorus trichloride under the action of an acid-binding agent, and the synergist is obtained by nucleophilic substitution reaction of the flame retardant and hydroxybenzotriazole; Preparation of the flame-retardant indigo composite dye: after dry grinding of a mixture of indigo, the synergist, a reducing agent and a dyeing promoter, wet grinding and drying and crushing are performed on the mixture and water, a surfactant and a hygroscopic agent to obtain the indigo composite dye.
2. The method of claim 1, wherein the method is characterized by, The structural formula of the halogenated alcohol is wherein n is a natural number of 2≤n≤6, and X is one of chlorine and bromine.
3. The method for preparing a flame-retardant indigo composite dye according to claim 1, characterized in that, The acid-binding agent is one of triethylamine, pyridine and N,N-diisopropyl ethylamine.
4. The method of claim 1, wherein the method is characterized by, The mass ratio of 4-nitropyridine and halogenated alcohol is 21-25:16-27.4, the mass ratio of the antistatic monomer, phosphorus trichloride and the acid-binding agent is 78-91:17-19:40-46, and the mass ratio of the flame retardant and hydroxybenzotriazole is 52-62:38-44.
5. The method for preparing a flame-retardant indigo composite dye according to claim 1, characterized in that, The reducing agent is at least one of sodium sulfide, sodium sulfite and sodium hydrosulfite.
6. The method of claim 1, wherein the method is characterized by, The dyeing promoter is at least one of sodium carbonate, sodium chloride and sodium sulfate.
7. The method for preparing a flame-retardant indigo composite dye according to claim 1, characterized in that, The surfactant is at least one of Tween 60, Tween 65 and Tween 80.
8. The method of claim 1, wherein the method is characterized by, The hygroscopic agent is at least one of ethanol, ethylene glycol and propylene glycol.
9. The method of claim 1, wherein the method is a method of preparing a flame-retardant indigo composite dye, characterized by, The mass ratio of indigo, the synergist, the reducing agent, the dyeing promoter, water, the surfactant and the hygroscopic agent is 100-110:50-60:50-55:50-60:250-280:15-16:20-22.
10. A flame-retardant indigo composite dye, characterized by comprising The flame-retardant indigo composite dye is prepared by the preparation method in any one of claims 1-9.