Melamine in-situ supramolecular self-assembly flame-retardant finishing liquid, preparation method and application thereof, flame-retardant suede fabric and preparation method thereof

Abstract

The invention provides a melamine in-situ supramolecular self-assembly flame-retardant finishing liquid, a preparation method and application thereof, a flame-retardant suede fabric and a preparation method of the flame-retardant suede fabric, and belongs to the technical field of flame-retardant treatment of textiles. According to the invention, the adopted melamine has certain flame-retardant property, and can cooperate with other components in the in-situ supramolecular self-assembly process with the other components, so that the formed flame-retardant system can effectively inhibit the combustion of the fabric. When the suede fabric is on fire, the flame-retardant system can capture free radicals in a gas phase, dilute the concentration of combustible gas, catalyze charring in a condensed phase, form a barrier layer and prevent heat and oxygen transmission, so that the flame-retardant capability of the fabric is remarkably improved, and the risk of fire occurrence is reduced. In addition, the flame-retardant finishing liquid is firmly attached to the fabric through multiple times of finishing, and a stable flame-retardant structure is formed. The combination mode enables the flame-retardant effect to have good durability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of textile flame-retardant treatment, and particularly relates to a melamine in-situ supramolecular self-assembly flame-retardant finishing liquid, a preparation method and application thereof, and a flame-retardant suede fabric and a preparation method thereof. BACKGROUND

[0002] With the rapid development of modern textile industry, people's performance requirements for textiles are increasing, especially in terms of flame retardant performance. Suede fabric, as a kind of high-grade synthetic leather material, is widely used in clothing, home decoration, automotive interior and other fields due to its soft hand feeling and appearance similar to real leather. However, suede fabric is flammable and releases toxic smoke during combustion, which poses a serious threat to people's life and property safety.

[0003] In recent years, the development of environmentally friendly and efficient flame retardants and their treatment technology has become a research hotspot in the textile industry. Melamine, as a compound with high nitrogen content, has potential flame-retardant effect, and its raw material source is widely available and relatively low in price. However, melamine mainly releases ammonia gas to dilute oxygen and inhibit free radicals through gas-phase flame-retardant mechanism, but lacks condensed-phase flame-retardant effect and has weak carbonization ability, so its flame-retardant efficiency is limited when used alone. Therefore, melamine is usually combined with phosphorus-containing compounds to form a synergistic flame-retardant system. The phosphorus-containing compounds can catalyze the dehydration and carbonization of cellulose to form a heat-insulating carbon layer in the condensed phase, while releasing phosphoric acid and polyphosphoric acid to inhibit pyrolysis. In the gas phase, phosphorus-containing radicals are generated to capture active groups in the combustion chain reaction. When combined with melamine, the nitrogen-phosphorus synergistic effect can enhance both gas-phase flame retardation and condensed-phase carbonation, significantly improving the flame-retardant efficiency.

[0004] In the prior art, melamine is often used in combination with phytic acid. Phytic acid contains six phosphate groups, has high phosphorus content and is environmentally friendly. When combined with melamine, it mainly forms a dynamic flame-retardant network through ionic bonds to improve the flame-retardant performance of the material. However, the production cost of phytic acid is relatively high. SUMMARY

[0005] The present application provides a melamine in-situ supramolecular self-assembly flame-retardant finishing liquid, a preparation method and application thereof, and a flame-retardant suede fabric and a preparation method thereof. The low-cost phosphorus-containing melamine derivative (hexamethyl melamine phosphonic acid) is used to replace phytic acid, which reduces the cost through a single raw material synthesis path while retaining the multi-phosphoric acid group and nitrogen-phosphorus synergistic mechanism, helping to improve the economy and practicality of the flame-retardant system. Moreover, the flame-retardant finishing liquid can be used to finish the suede fabric based on the melamine in-situ supramolecular self-assembly flame-retardant finishing method, which can improve the flame-retardant performance of the suede fabric while maintaining its original hand feeling and appearance, and reducing the environmental impact and production cost.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions: This invention provides a method for preparing a melamine in-situ supramolecular self-assembled flame-retardant finishing liquid, comprising the following steps: Formaldehyde, melamine, alkali and water are mixed and subjected to the first reaction to obtain melamine derivatives. The melamine derivative, phosphoric acid, and water were mixed to carry out a second reaction to obtain hexamethylmelaminephosphonic acid. The hexamethylmelamine phosphonic acid was mixed with water, and the resulting hexamethylmelamine phosphonic acid solution was added dropwise to a melamine aqueous solution for physical mixing to obtain a melamine in-situ supramolecular self-assembled flame retardant finishing liquid.

[0007] Preferably, the alkali includes sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, ethylenediamine, or triethanolamine; The mixing of formaldehyde, melamine, alkali, and water includes: adding formaldehyde dropwise to a portion of the water, dissolving the alkali in the remaining water, adding the resulting alkali solution dropwise to the resulting formaldehyde solution, adjusting the pH of the mixture to 9-10, and adding melamine to the resulting mixture.

[0008] Preferably, the mass concentration of the alkaline aqueous solution is 1-5%; the molar ratio of formaldehyde to melamine is 6-10:1. The temperature of the first reaction is 40~60℃, and the time is 3~5h.

[0009] Preferably, the mixing of the melamine derivative, phosphoric acid, and water comprises: dissolving the melamine derivative in water, and adding phosphoric acid dropwise to the resulting melamine derivative solution; the concentration of the melamine derivative solution is 0.5~3 g / mL; the mass concentration of the phosphoric acid is 85%; and the molar ratio of the melamine derivative to the phosphoric acid is 1:6~10. The temperature of the second reaction is 30~70℃, and the time is 2~6h.

[0010] Preferably, the mass concentration of the hexamethylmelamine phosphonic acid solution is 1-10%; the mass concentration of the melamine aqueous solution is 0.5-2%; in the physical mixing step, the molar ratio of the hexamethylmelamine phosphonic acid to the melamine in the melamine aqueous solution is 0.5-1.5:1; the physical mixing temperature is 80-100℃, and the time is 20-40 min.

[0011] This invention provides a melamine in-situ supramolecular self-assembled flame retardant finishing liquid prepared by the preparation method described in the above technical solution.

[0012] This invention provides the application of the melamine in-situ supramolecular self-assembled flame retardant finishing liquid described above in the field of flame retardant finishing of suede-like fabrics.

[0013] This invention provides a method for preparing flame-retardant suede-like fabric, comprising the following steps: 1) The imitation suede fabric is immersed in an alkaline solution for pretreatment to obtain the treated imitation suede fabric; 2) After heating the melamine in-situ supramolecular self-assembly flame retardant finishing liquid described in the above technical solution, the treated imitation suede fabric is immersed in the melamine in-situ supramolecular self-assembly flame retardant finishing liquid, and then squeezed and dried in sequence to complete a single finishing process. 3) Repeat step 2) until the target number of finishing steps is reached, then cure the resulting fabric to obtain flame-retardant suede-like fabric.

[0014] Preferably, the alkaline solution comprises an aqueous solution of sodium hydroxide; the concentration of the alkaline solution is 1-5%; and the pretreatment time is 0.5-5 hours. The heat treatment is performed at a temperature of 70~90℃ for 5~10 minutes. In step 2), the immersion time for each treatment of the suede-like fabric is 20-40 minutes, the pressure for each compression is 1-5 bar, and the temperature for each drying is 40-90°C. The number of target finishing treatments is 2-6, and the temperature for the curing treatment is 170-190°C.

[0015] The present invention provides a flame-retardant imitation suede fabric prepared by the preparation method described in the above technical solution.

[0016] The technical solution of the present invention has the following beneficial effects: 1) A nitrogen-phosphorus synergistic flame retardant system is constructed by combining melamine with a specific phosphorus-containing derivative (hexamethylmelamine phosphonic acid). Phosphorus can provide condensed phase flame retardancy by generating a char layer, while nitrogen can provide gas phase flame retardancy by generating nitrogen gas. Not only does melamine release ammonia gas in the gas phase to dilute oxygen and inhibit free radicals, but phosphorus-containing compounds also generate phosphorus-containing free radicals to capture active groups in the combustion chain reaction. In terms of condensed phase flame retardancy, phosphorus-containing compounds can also catalyze the dehydration and carbonization of cellulose to form a heat-insulating char layer, while releasing phosphoric acid and polyphosphoric acid to inhibit pyrolysis, significantly improving the flame retardant efficiency of suede-like fabrics and effectively reducing the risk of fire.

[0017] 2) Low-cost, structurally similar phosphorus-containing melamine derivatives are used to replace phytic acid, which has a higher production cost. By simplifying the raw material synthesis route, the raw material cost is reduced, while the polyphosphate groups and nitrogen-phosphorus synergistic mechanism are retained, which improves the economy and practicality of the flame retardant system.

[0018] 3) The present invention is based on the in-situ supramolecular self-assembly flame retardant finishing method of melamine, which can improve the flame retardant performance of suede-like fabrics while effectively maintaining their original soft hand feel and leather-like appearance, without affecting the application effect of the fabrics in clothing, home decoration, automotive interiors and other fields. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation process of the flame-retardant suede-like fabric of the present invention. Figure 2 The images shown are scanning electron microscope (SEM) images of the flame-retardant imitation suede fabric before and after finishing and after burning in Example 1 of the present invention. A1 and A2 are SEM images of the imitation suede without any treatment at different magnifications. B1 and B2 are SEM images of the imitation suede after finishing with flame retardant liquid at different magnifications. C1 and C2 are SEM images of the flame-retardant imitation suede fabric after ignition at room temperature for 20 seconds. Figure 3 The figures show vertical burning experiments of the flame-retardant imitation suede fabric before and after finishing in Embodiment 1 of the present invention; A is the untreated imitation suede fabric, and B is the flame-retardant finished imitation suede fabric. Figure 4 This is a comparison chart of the limiting oxygen index values ​​of flame-retardant imitation suede fabric and imitation suede during combustion in Examples 1-3 and Comparative Examples 1-2 of the present invention. Figure 5 The structural formula of the melamine derivative prepared in Example 1 is shown below; Figure 6 The structural formula of hexamethylmelaminephosphonic acid prepared in Example 1 is shown below; Figure 7 The NMR spectrum of the melamine derivative prepared in Example 1; Figure 8 The hexamethylmelamine phosphonic acid prepared in Example 1 1 H NMR spectrum. Detailed Implementation

[0020] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0021] This invention provides a method for preparing a melamine in-situ supramolecular self-assembled flame-retardant finishing liquid, comprising the following steps: Formaldehyde, melamine, alkali and water are mixed and subjected to the first reaction to obtain melamine derivatives. The melamine derivative, phosphoric acid, and water were mixed to carry out a second reaction to obtain hexamethylmelaminephosphonic acid. The hexamethylmelamine phosphonic acid was mixed with water, and the resulting hexamethylmelamine phosphonic acid solution was added dropwise to a melamine aqueous solution for physical mixing to obtain a melamine in-situ supramolecular self-assembled flame retardant finishing liquid.

[0022] This invention involves mixing formaldehyde, melamine, alkali, and water to carry out a first reaction, thereby obtaining a melamine derivative.

[0023] In this invention, the formaldehyde is preferably a commercially available 37% formaldehyde solution.

[0024] In this invention, the alkali preferably includes sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, ethylenediamine or triethanolamine, and more preferably sodium hydroxide.

[0025] In this invention, the mixing of formaldehyde, melamine, alkali and water preferably includes: adding formaldehyde dropwise to a portion of the water, dissolving the alkali in the remaining water, adding the resulting alkali aqueous solution dropwise to the resulting formaldehyde aqueous solution, adjusting the pH of the mixture to 9-10, and adding melamine to the resulting mixture.

[0026] In this invention, the mass concentration of the alkaline aqueous solution is preferably 1-5%, more preferably 1-3%; the molar ratio of formaldehyde to melamine is preferably 6-10:1, more preferably 6-8:1. The amount of alkali used in this invention is sufficient to achieve the desired pH value.

[0027] After adding melamine, the present invention preferably uses a constant temperature water bath to heat and stir the reaction solution to carry out the first reaction. After cooling and precipitation, white crystals are obtained. The solution is filtered to remove water and residual formaldehyde. The crystals are washed with deionized water 3 to 6 times to fully remove the formaldehyde. The solution is then dried in a vacuum oven to obtain the melamine derivative. The drying temperature is preferably 50 to 70°C, more preferably 50 to 60°C.

[0028] In this invention, the temperature of the first reaction is preferably 40~60℃, more preferably 45~55℃, and even more preferably 50℃, and the time is preferably 3~5h, more preferably 3~4h.

[0029] After obtaining the melamine derivative, the present invention mixes the melamine derivative, phosphoric acid and water to carry out a second reaction to obtain hexamethylmelaminephosphonic acid.

[0030] In this invention, the mixing of melamine derivative, phosphoric acid, and water preferably comprises: dissolving the melamine derivative in water, and adding phosphoric acid dropwise to the resulting melamine derivative solution; the concentration of the melamine derivative solution is preferably 0.5~3 g / mL, more preferably 1~2 g / mL; the mass concentration of the phosphoric acid is preferably 85%; the molar ratio of the melamine derivative to the phosphoric acid is preferably 1:6~10, more preferably 1:6~8.

[0031] After adding acid, the present invention preferably stirs the resulting mixture in a constant temperature water bath with a magnetic stirrer to carry out a second reaction, obtaining a colorless and transparent liquid, removing moisture by a freeze-drying device, and drying in a vacuum oven; the drying temperature is preferably 40~80℃, more preferably 60℃.

[0032] In this invention, the temperature of the second reaction is preferably 30~70℃, more preferably 30~50℃, and the time is preferably 2~6h, more preferably 2~5h.

[0033] After obtaining hexamethylmelamine phosphonic acid, the present invention mixes the hexamethylmelamine phosphonic acid with water, and adds the resulting hexamethylmelamine phosphonic acid solution dropwise into an aqueous melamine solution for physical mixing to obtain an in-situ supramolecular self-assembled flame retardant finishing liquid of melamine.

[0034] The present invention preferably involves dissolving melamine in deionized water and heating it to 10°C. C. Stir to dissolve, and obtain melamine aqueous solution. Mix hexamethylmelamine phosphonic acid with water. Add the obtained hexamethylmelamine phosphonic acid solution dropwise to melamine aqueous solution. Perform physical mixing by magnetic stirring to obtain melamine in-situ supramolecular self-assembled flame retardant finishing liquid.

[0035] In this invention, the mass concentration of the hexamethylmelamine phosphonic acid solution is preferably 1-10%, more preferably 3-8%, and even more preferably 5%; the mass concentration of the melamine aqueous solution is preferably 0.5-2%, more preferably 1-2%; in the physical mixing step, the molar ratio of the hexamethylmelamine phosphonic acid to the melamine in the melamine aqueous solution is preferably 0.5-1.5:1, more preferably 0.6-1.2:1, and even more preferably 1.03:1.

[0036] In this invention, the temperature of the physical mixing is preferably 80~100℃, more preferably 90~95℃, and the time is preferably 20~40min, more preferably 30min.

[0037] This invention provides a melamine in-situ supramolecular self-assembled flame retardant finishing liquid prepared by the preparation method described in the above technical solution.

[0038] This invention provides the application of the melamine in-situ supramolecular self-assembled flame retardant finishing liquid described above in the field of flame retardant finishing of suede-like fabrics.

[0039] like Figure 1 As shown, the present invention provides a method for preparing flame-retardant suede-like fabric, comprising the following steps: 1) The imitation suede fabric is immersed in an alkaline solution for pretreatment to obtain the treated imitation suede fabric; 2) After heating the melamine in-situ supramolecular self-assembly flame retardant finishing liquid described in the above technical solution, the treated imitation suede fabric is immersed in the melamine in-situ supramolecular self-assembly flame retardant finishing liquid, and then squeezed and dried in sequence to complete a single finishing process. 3) Repeat step 2) until the target number of finishing steps is reached, then cure the resulting fabric to obtain flame-retardant suede-like fabric.

[0040] The present invention does not impose any special limitations on the specific source and specifications of the imitation suede fabric; commercially available products well known in the art are acceptable.

[0041] In this invention, the alkaline solution preferably comprises an aqueous solution of sodium hydroxide; the concentration of the alkaline solution is preferably 1-5%, more preferably 2-3%; and the pretreatment time is preferably 0.5-5 h, more preferably 1-2 h.

[0042] After the pretreatment, the present invention preferably washes the resulting fabric with deionized water and dries it in an oven; the drying temperature is preferably 40~90°C. C, more preferably 80°C.

[0043] In this invention, the temperature of the heat treatment is preferably 70~90℃, more preferably 75~85℃, and even more preferably 80℃, and the time is preferably 5~10min, more preferably 8~10min; the heat treatment is preferably carried out under the conditions of heating and stirring in a constant temperature water bath.

[0044] In this invention, in step 2), the soaking time of the treated suede fabric for each immersion is preferably 20-40 min, more preferably 25-35 min, and even more preferably 30 min; the pressure of each compression is preferably 1-5 bar, more preferably 2-3 bar; and the drying temperature for each drying is preferably 40-90°C, more preferably 60-90°C.

[0045] In this invention, the number of target finishing processes is preferably 2 to 6 times, more preferably 3 to 4 times, the temperature of the curing treatment is preferably 170 to 190°C, more preferably 180°C, and the time is preferably 15 minutes.

[0046] The present invention provides a flame-retardant imitation suede fabric prepared by the preparation method described in the above technical solution.

[0047] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0048] Unless otherwise specified, the experimental and testing methods described below are conventional methods; unless otherwise specified, the reagents and raw materials described below are commercially available.

[0049] Example 1

[0050] (1) Preparation of melamine in-situ supramolecular self-assembled flame retardant finishing liquid: First, 0.6 mol of 37% formaldehyde was added dropwise to 10 mL of distilled water and mixed thoroughly with magnetic stirring to obtain a formaldehyde aqueous solution. Then, 3.0 mL of 1% sodium hydroxide aqueous solution was added dropwise to the formaldehyde aqueous solution to adjust the pH to 9, resulting in a mixed solution. Finally, 0.1 mol of melamine was added to the above mixed solution, and the solution was stirred using a 5... The reaction solution was heated and stirred in a constant temperature water bath at C for 3 hours. After cooling, white crystals were obtained. The crystals were filtered to remove water and residual formaldehyde, washed three times with deionized water, and then... The melamine derivative was obtained by drying C in a vacuum oven. The structural formula is shown below. Figure 5 ; A melamine derivative solution with a concentration of 1.0 g / mL was prepared by dissolving the melamine derivative in deionized water. An 85% phosphoric acid solution (0.6 mol phosphoric acid) was then added dropwise to the melamine derivative solution (0.1 mol melamine derivative). In a constant-temperature water bath at C, the mixture was stirred with a magnetic stirrer for 2 hours to obtain a colorless and transparent liquid. After freeze-drying, it was then heated at 6... Hexamethylmelaminephosphonic acid was dried in a vacuum oven at C to obtain hexamethylmelaminephosphonic acid, the structural formula of which is shown below. Figure 6 ; Dissolve 1 g of melamine (7.9 mmol) in 50 mL of deionized water and heat to 10 °C. C. Stir until completely dissolved to obtain a 2% melamine aqueous solution; take 2.5g of hexamethylmelamine phosphonic acid (8.1mmol) and add it to 50mL of deionized water to prepare a 5% hexamethylmelamine phosphonic acid solution. Add the obtained hexamethylmelamine phosphonic acid solution dropwise to the obtained 2% melamine aqueous solution and stir magnetically at 90℃ for 30min to obtain a melamine in-situ supramolecular self-assembled flame retardant finishing liquid.

[0051] (2) Preparation of flame-retardant suede-like fabric: Imitation suede fabric (Zhejiang Meisheng New Material Co., Ltd.; weight 274g / m²) 2 Soak in a 3% sodium hydroxide aqueous solution for 2 hours, then rinse thoroughly with deionized water and place in an 8-inch container. Drying process in an oven of type C; The melamine in-situ supramolecular self-assembled flame retardant finishing liquid prepared above was subjected to 8... The mixture is heated and stirred in a constant temperature water bath for 5 minutes (C), then the pretreated suede fabric is immersed in the finishing solution for 30 minutes. After removal, it is squeezed under a pressure of 2 bar, and then subjected to 9... Dry in oven C to complete a single finishing process; repeat this process 3 times until the target number of finishing processes is reached, then dry the suede-like fabric in an oven at 18°C. The flame-retardant imitation suede fabric is obtained by curing it in an oven at temperature C for 15 minutes.

[0052] Example 2

[0053] The only difference from Example 1 is that the single sorting process in step (2) is repeated once.

[0054] Example 3

[0055] The only difference from Example 1 is that the single sorting process in step (2) is repeated 5 times.

[0056] Comparative Example 1

[0057] A method for preparing flame-retardant suede-like fabric, comprising the following steps: (1) Preparation of flame retardant finishing liquid: The melamine derivative prepared in Example 1 was dissolved in deionized water to prepare a solution with a concentration of 0.5 g / mL, which yielded a flame-retardant finishing liquid; (2) Preparation of flame-retardant imitation suede fabric: Same as in Example 1.

[0058] Comparative Example 2

[0059] A method for preparing flame-retardant suede-like fabric, comprising the following steps: (1) Preparation of flame retardant finishing liquid: 2.5g of hexamethylmelaminephosphonic acid prepared in Example 1 was added to 50 mL of deionized water to prepare a 5% solution, thus obtaining a flame retardant finishing liquid.

[0060] (2) Preparation of flame-retardant imitation suede fabric: Same as in Example 1.

[0061] Structural characterization and testing

[0062] Figure 2 These are scanning electron microscope (SEM) images of the flame-retardant suede-like fabric before and after treatment, and after combustion, in Example 1 of this invention; A1 and A2 are SEM images of the untreated suede-like fabric at different magnifications; B1 and B2 are SEM images of the flame-retardant suede-like fabric treated with flame retardant liquid at different magnifications; C1 and C2 are SEM images of the flame-retardant suede-like fabric after ignition at room temperature for 20 seconds. Figure 2It can be seen that the untreated suede fibers in A1 and A2 have smooth surfaces, relatively loose fiber arrangement, and no special structure or substances attached. Comparing B1 and B2 with A1 and A2, the suede fibers treated with the flame-retardant liquid show no change in structure, but substances are observed adhering to their surfaces. This indicates that the flame-retardant liquid, loaded on the fiber surface, may have formed a flame-retardant coating, laying the foundation for subsequent flame-retardant action. In C1 and C2, the flame-retardant suede fabrics after combustion show significant changes in fiber surface structure, forming a relatively dense char layer. This char layer effectively blocks heat transfer and oxygen contact, exerting a condensed phase flame-retardant effect. This proves that the flame-retardant liquid enables the suede fabric to form an effective heat-insulating protective structure during combustion, improving its flame-retardant performance.

[0063] Figure 3 These are vertical burning test images of the flame-retardant suede-like fabric before and after finishing in Embodiment 1 of the present invention; A is the untreated suede-like fabric, and B is the flame-retardant finished suede-like fabric. Figure 3 As shown in Figure A, the untreated fabric initially appears normal (0s). Small flames appear at 5s, the flames significantly increase at 10s, and the fire spreads rapidly at 15s, causing extensive burning of the fabric. From 20s to 30s, the flames continue to rage, severely damaging the fabric. This indicates that the untreated imitation suede fabric is highly flammable and has poor flame-retardant properties. The flame-retardant treated imitation suede fabric (…) Figure 3 (B) The material was in good condition at 0s. From 5s to 15s, there was only a weak ignition source reaction with no obvious flame expansion. At 20s, there was a slight change but no large flame formed. From 25s to 30s, there was a small-scale reaction, but the overall material remained relatively intact with only minor damage. This indicates that after flame-retardant treatment, the flame-retardant performance of the suede-like fabric was significantly improved, effectively inhibiting flame spread and reducing the degree of combustion.

[0064] Figure 4 This is a comparison chart of the limiting oxygen index values ​​of flame-retardant imitation suede fabric and imitation suede during combustion in Examples 1-3 and Comparative Examples 1-2 of the present invention; from Figure 4 Comparing the limiting oxygen index (LOI) values, the pure suede-like fabric has an LOI of only 20.4%, highlighting its flammability and highlighting the need for improved flame retardant performance. While Comparative Example 1 showed improvement, its LOI only increased to 21.8%, indicating limited improvement in flame retardant effect. Comparative Example 2 increased its LOI to 30.8%, demonstrating enhanced flame retardant performance. However, the limiting oxygen index of Example 1 of this invention reached as high as 34.4%, Example 2 was 31.4%, and Example 3 even reached 39.2%. This indicates that the flame retardant treatment scheme of this invention can significantly improve the flame retardant performance of the suede-like fabric, and the flame retardant effect increases positively with the number of flame retardant treatments. The overall flame retardant effect is superior to the control group, and it can more effectively meet the stringent requirements for flame retardancy in practical applications.

[0065] Figure 7The NMR spectrum of the melamine derivative prepared in Example 1 confirms its successful synthesis.

[0066] Figure 8 The hexamethylmelamine phosphonic acid prepared in Example 1 1 H NMR spectrum; by Figure 8 The presence of -CH2- absorption peaks at 4.59 and 4.67 ppm, and an absorption peak at 6.08 ppm, confirms the successful synthesis of hexamethylmelamine phosphonic acid.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a melamine in-situ supramolecular self-assembled flame-retardant finishing liquid, characterized in that, Includes the following steps: Formaldehyde, melamine, alkali and water are mixed and subjected to the first reaction to obtain melamine derivatives. The melamine derivative, phosphoric acid, and water were mixed to carry out a second reaction to obtain hexamethylmelaminephosphonic acid. The hexamethylmelamine phosphonic acid was mixed with water, and the resulting hexamethylmelamine phosphonic acid solution was added dropwise to a melamine aqueous solution for physical mixing to obtain a melamine in-situ supramolecular self-assembled flame retardant finishing liquid.

2. The preparation method according to claim 1, characterized in that, The alkali includes sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, ethylenediamine, or triethanolamine; The mixing of formaldehyde, melamine, alkali, and water includes: adding formaldehyde dropwise to a portion of the water, dissolving the alkali in the remaining water, adding the resulting alkali solution dropwise to the resulting formaldehyde solution, adjusting the pH of the mixture to 9-10, and adding melamine to the resulting mixture.

3. The preparation method according to claim 2, characterized in that, The mass concentration of the alkaline aqueous solution is 1-5%; the molar ratio of formaldehyde to melamine is 6-10:

1. The temperature of the first reaction is 40~60℃, and the time is 3~5h.

4. The preparation method according to claim 1 or 3, characterized in that, The mixing of melamine derivative, phosphoric acid, and water comprises: dissolving the melamine derivative in water, and adding phosphoric acid dropwise to the resulting melamine derivative solution; the concentration of the melamine derivative solution is 0.5~3 g / mL; the mass concentration of the phosphoric acid is 85%; and the molar ratio of the melamine derivative to the phosphoric acid is 1:6~10. The temperature of the second reaction is 30~70℃, and the time is 2~6h.

5. The preparation method according to claim 4, characterized in that, The mass concentration of the hexamethylmelamine phosphonic acid solution is 1-10%; the mass concentration of the melamine aqueous solution is 0.5-2%; in the physical mixing step, the molar ratio of the hexamethylmelamine phosphonic acid to the melamine in the melamine aqueous solution is 0.5-1.5:1; the physical mixing temperature is 80-100℃ and the time is 20-40 min.

6. The melamine in-situ supramolecular self-assembled flame retardant finishing liquid prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the melamine in-situ supramolecular self-assembled flame retardant finishing liquid according to claim 6 in the field of flame retardant finishing of suede-like fabrics.

8. A method for preparing flame-retardant suede-like fabric, characterized in that, Includes the following steps: 1) The imitation suede fabric is immersed in an alkaline solution for pretreatment to obtain the treated imitation suede fabric; 2) After heating the melamine in-situ supramolecular self-assembly flame retardant finishing liquid according to claim 6, the treated suede-like fabric is immersed in the melamine in-situ supramolecular self-assembly flame retardant finishing liquid, and then squeezed and dried in sequence to complete a single finishing process. 3) Repeat step 2) until the target number of finishing steps is reached, then cure the resulting fabric to obtain flame-retardant suede-like fabric.

9. The preparation method according to claim 8, characterized in that, The alkaline solution comprises an aqueous sodium hydroxide solution; the concentration of the alkaline solution is 1-5%; the pretreatment time is 0.5-5 hours. The heat treatment temperature is 70~90℃ and the time is 5~10min; in step 2), the immersion time of each treatment of the imitation suede fabric is 20~40min, the pressure of each extrusion is 1~5 bar, and the temperature of each drying is 40~90℃; the target finishing number is 2~6 times, and the curing temperature is 170~190℃.

10. The flame-retardant suede-like fabric prepared by the preparation method of claim 8 or 9.

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