Preparation method of phytic acid-based flame retardant and flame-retardant cotton fabric

Abstract

The invention belongs to the field of flame-retardant finishing of textiles, and discloses a phytic acid-based flame retardant and a preparation method of a flame-retardant cotton fabric. Natural phytic acid, polyethylene glycol, melamine and metal salt are used as main raw materials, the environment-friendly characteristic of a biomass material is combined, an efficient and environment-friendly flame retardant is prepared, the prepared flame retardant is arranged on a cotton fabric through a traditional impregnation method, and the flame retardance and smoke suppression performance of the arranged cotton fabric are greatly improved. The method not only has a good flame retardant effect, but also avoids potential hazards of a traditional flame retardant to the environment and human health, and has a wide application prospect. The flame-retardant cotton fabric can be widely applied to the fields of household textiles, protective clothing, fire-fighting equipment and the like, and has remarkable economic benefits and social benefits. The invention not only provides an efficient and environment-friendly flame retardant preparation method, but also opens up a new way for application of biomass materials in the field of flame retardance, and has important scientific significance and practical value.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of phytic acid-based flame retardant and flame-retardant cotton fabric, and belongs to the field of flame-retardant finishing of textiles. BACKGROUND

[0002] Cotton fabric occupies an important position in the fields of clothing, home textiles and industry due to its excellent softness, air permeability and comfort. However, as a natural cellulose material, cotton fabric has a highly flammable characteristic, which not only releases a large amount of heat energy and is accompanied by the diffusion of dense smoke during combustion, but also causes rapid flame spread, bringing significant safety hazards. This characteristic has prompted the enhancement of the flame retardant performance of cotton fabric to become a key research topic in the field of textile materials. In the current mainstream chemical flame retardant treatment technology, the application of traditional flame retardants faces significant limitations: from the perspective of raw material sustainability, mainstream flame retardants such as halogen-based and phosphorus-based ones rely on non-renewable petroleum-based raw materials; in terms of safety and environmental protection, the release of dioxin and other toxic gases during the combustion of halogen-based flame retardants can cause serious ecological pollution and health hazards; while phosphorus-based flame retardants have good flame retardant efficiency, they have application bottlenecks such as insufficient wash fastness and water eutrophication risk.

[0003] With the improvement of global environmental awareness and the deepening of the concept of green chemistry, the development of biomass-based flame retardants has become an important direction to break through the difficulties of traditional technology. As a representative of natural organic phosphoric compounds, phytic acid is widely distributed in plant seeds, and its six phosphate groups in the molecular structure endow it with unique flame retardant advantages. During pyrolysis, phytic acid can promote the formation of a dense carbon layer through catalytic dehydration, effectively building a physical barrier to isolate heat and oxygen transmission, and achieving a condensed phase flame retardant mechanism. More notably, this bio-based material has the characteristics of renewability, non-toxicity and biodegradability, fully meeting the sustainable development requirements of green chemistry.

[0004] Current research shows that the application of phytic acid-based flame retardant systems on cotton fabric has made significant progress, but its actual industrialization still faces multiple challenges: first, the insufficient interfacial bonding strength between phytic acid molecules and cellulose matrix leads to poor wash resistance of the treated fabric; second, multiple chemical modifications are often required to achieve long-lasting flame retardant effect, which increases the complexity and cost of the process, restricting large-scale production. The breakthrough of these technical bottlenecks will depend on the coordinated development of molecular structure design innovation and green processing technology, which has become a key research direction in the future. SUMMARY

[0005] The present application relates to a preparation method of phytic acid-based flame retardant and flame-retardant cotton fabric, aiming to provide an efficient and environmentally friendly flame retardant to solve the environmental hazards of traditional flame retardants and the flammability of cotton fabric. The advantages of the present application mainly lie in the following aspects: first, efficient flame retardation, the synergistic effect of phytic acid and polyethylene glycol 200 endows the cotton fabric with excellent flame retardant performance, and the gas source effect of melamine further enhances the flame retardant effect; second, environmental friendliness, using natural phytic acid and biomass materials as main raw materials avoids the use of harmful substances such as halogen and phosphorus in traditional flame retardants; third, smoke suppression performance, the introduction of metal ions significantly reduces the smoke release during combustion, improving the safety of flame-retardant cotton fabric.

[0006] The present application provides an efficient and environmentally friendly preparation method of phytic acid-based flame retardant, providing a new solution for the flame retardant treatment of cotton fabric, which has important scientific significance and application value. The innovation of the present application lies in the modification of phytic acid by polyethylene glycol, the use of melamine as a gas source and the introduction of metal ions, realizing the efficiency and environmental friendliness of the flame retardant, and opening up a new way for the development of green flame retardant technology.

[0007] The specific technical scheme of the present application is as follows:

[0008] In order to solve the above-mentioned problems, the present application aims to provide a preparation method of phytic acid-based flame retardant, which adopts traditional impregnation process during finishing, is simple to operate and has high performance of flame retardant.

[0009] The first object of the present application is to provide a preparation method of phytic acid-based flame retardant, which specifically comprises the following steps:

[0010] Step 1: Add phytic acid (PA) to a three-necked flask, stir in an oil bath under nitrogen atmosphere until no water droplets are generated at the gas outlet, and obtain treated phytic acid.

[0011] Step 2: Add polyethylene glycol (PEG) to the treated phytic acid obtained in step 1, heat and react, modify the phytic acid with polyethylene glycol, and obtain a black viscous product, i.e. modified phytic acid (phytic acid-g-PEG).

[0012] Step 3: Dissolve the modified phytic acid obtained in step 2 in deionized water, add melamine (MEL) after fully dissolving, mix, and then perform hydrothermal reaction after uniform mixing to obtain a modified phytic acid / melamine solution.

[0013] Step 4: After the pH of the modified phytic acid / melamine solution obtained in step 3 is adjusted to 6-7 using a base solution, a metal salt is added, and after sufficient reaction, the prepared solution product is refrigerated and allowed to stand, to obtain a precipitate product, the precipitate solution is centrifuged, and the precipitate product after centrifugation is washed and dried to obtain a phytic acid-based flame retardant (phytic acid-g-PEG / melamine metal complex flame retardant). The metal salt is at least one of nickel chloride, ferric chloride, and lanthanum chloride.

[0014] In one embodiment, in step 1, the phytic acid is a phytic acid solution, and the concentration of the phytic acid solution is in the range of 40%-70%; preferably, the concentration of the phytic acid solution is 70%.

[0015] In one embodiment, in step 1, the stirring temperature is 130-150°C, and the stirring time is 1-2h. Preferably, the reaction temperature is 135°C, and the reaction time is 2h.

[0016] In one embodiment, in step 2, the molecular weight of the polyethylene glycol is 200-2000.

[0017] In one embodiment, in step 2, the molar ratio of phytic acid to polyethylene glycol is 1:3-6, the reaction temperature is 130-150°C, and the reaction time is 5-6h, and the reaction is carried out under a nitrogen atmosphere. Preferably, the molar ratio of phytic acid to polyethylene glycol is 1:3, the reaction temperature is 135°C, and the reaction time is 5h.

[0018] In one embodiment, in step 3, the molar ratio of phytic acid to melamine is 1:3-6, the reaction temperature is 80-90°C, and the reaction time is 2-3h, and the reaction is carried out under a nitrogen atmosphere. Preferably, the molar ratio of phytic acid to melamine is 1:3, the reaction temperature is 85°C, and the reaction time is 2h.

[0019] In one embodiment, in step 3, the ratio of phytic acid to deionized water is 0.01 mol:200-500mL, preferably 0.01 mol:350mL, for example.

[0020] In one embodiment, in step 3, the modified phytic acid is fully dissolved under heating, and the heating temperature is 70-90°C; preferably, the heating temperature is 85°C.

[0021] In one embodiment, in step 4, the molar ratio of phytic acid to metal salt is 1:3-6, the reaction temperature is 80-90°C, and the reaction time is 0.5-1h, and the reaction is carried out under a nitrogen atmosphere. Preferably, the pH is 7, the molar ratio of phytic acid to metal salt is 1:3, the reaction temperature is 85°C, and the reaction time is 1h.

[0022] In one embodiment, in step 4, the base is sodium hydroxide, ammonia water, etc.

[0023] In one embodiment, in step 4, the temperature range of refrigeration is 0-5℃, and the standing time is 10-18h, preferably 12h.

[0024] In one embodiment, in step 4, the cotton fabric is washed with deionized water.

[0025] In one embodiment, the flow rate of nitrogen is 200-400L / min, preferably 200L / min.

[0026] The second object of the present application is to provide a phytic acid-based flame retardant prepared by the above preparation method.

[0027] The third object of the present application is the use of the phytic acid-based flame retardant in the preparation of flame-retardant cotton fabric.

[0028] The fourth object of the present application is to provide a preparation method of flame-retardant cotton fabric, comprising the following steps:

[0029] The cotton fabric is immersed in the phytic acid flame retardant solution for finishing treatment, and then dried to obtain the flame-retardant cotton fabric.

[0030] In one embodiment, the preparation method of the flame-retardant cotton fabric comprises the following steps:

[0031] Step 1: The cotton fabric is immersed in an alkali solution for pretreatment, and then washed with deionized water and dried at room temperature to obtain the pretreated cotton fabric.

[0032] Step 2: The pretreated cotton fabric obtained in step 1 is immersed in the phytic acid-based flame retardant solution for finishing treatment, and then dried to obtain the flame-retardant cotton fabric.

[0033] In one embodiment, the alkali solution is sodium hydroxide solution.

[0034] In one embodiment, the concentration of the alkali solution for pretreatment is 1wt%-10wt%, the immersion temperature is 70℃-90℃, the immersion time is 1-2h, and the bath ratio is 1:20-40. Preferably, the concentration of the alkali solution is 2wt%, the immersion temperature is 70℃, the immersion time is 1h, and the bath ratio is 1:20.

[0035] In one embodiment, the concentration of the finishing treatment phytic acid-based flame retardant solution is 5wt%-20wt%, the dipping temperature is 40-60℃, the dipping time is 1-10min, and the bath ratio is 1:20-40. Preferably, the concentration of the phytic acid-based flame retardant solution is 5wt%, the dipping temperature is 40℃, the dipping time is 10min, the drying temperature is 70℃, and the bath ratio is 1:20.

[0036] In one embodiment, the drying temperature is 60-80℃, preferably 70℃.

[0037] In one embodiment, the finishing treatment and drying can be repeated multiple times, and the cotton fabric is increased by 10%-40% by repeating the finishing treatment-drying process multiple times.

[0038] The present application provides a preparation method of phytic acid-based flame retardant and flame-retardant cotton fabric. By using natural phytic acid, polyethylene glycol, melamine and metal salt (nickel chloride, ferric chloride and lanthanum chloride) as main raw materials, combining the environmental protection characteristics of biomass materials, a high-efficiency and environmentally-friendly flame retardant is prepared, and the prepared flame retardant is finished on the cotton fabric by traditional dipping method, and the flame-retardant and smoke-suppressing performance of the finished cotton fabric is greatly improved. The method not only has good flame-retardant effect, but also avoids the potential harm of traditional flame retardants to the environment and human health, and has wide application prospect.

[0039] Firstly, the PEG is used to modify the PA, the esterification reaction occurs between the hydroxyl group of PEG and the phosphate group of phytic acid to generate modified phytic acid (phytic acid-g-PEG), so as to improve the water solubility and compatibility with cotton fabric; secondly, the phytic acid-g-PEG is reacted with MEL, the MEL is used as a gas source, and the inert gas (such as ammonia) is generated at high temperature, so as to dilute the combustible gas and form an expanded carbon layer, thereby enhancing the flame-retardant effect; finally, the metal ion is introduced to form a stable complex with phytic acid-g-PEG and MEL, which not only improves the thermal stability of the flame retardant, but also significantly enhances the smoke suppression effect and reduces the release of toxic smoke in the combustion process.

[0040] The phytic acid-g-PEG / melamine metal complex flame-retardant cotton fabric provided by the present application uses natural phytic acid as raw material, and combines the synergistic effect of polyethylene glycol, melamine and metal ions, so that the flame-retardant effect is remarkable, and no toxic gas is released during combustion, which is safe and environmentally friendly. Through the dipping process, the flame-retardant cotton fabric is uniformly distributed in the fiber inside and surface of the cotton fabric, which can significantly reduce the heat transfer in the combustion process, effectively inhibit the flame spread, reduce the smoke release, and maintain the structural integrity of the fabric.

[0041] The flame-retardant cotton fabric of the application can be widely applied in the fields of home textiles, protective clothing, fire-fighting equipment and the like, and has significant economic and social benefits. The application not only provides a preparation method of the efficient and environment-friendly flame retardant, but also opens up a new way for the application of biomass materials in the field of flame retardation, and has important scientific significance and practical value. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is a preparation flowchart of the phytic acid-based flame retardant and the flame-retardant cotton fabric.

[0043] Figure 2 It is a residual carbon graph of the flame-retardant cotton fabric prepared in Examples 2-4; wherein (a) is a residual carbon graph of pure cotton fabric; (b) is a residual carbon of the cotton fabric with 10% weight gain of PPMN flame-retardant finishing in Example 2; (c) is a residual carbon of the cotton fabric with 20% weight gain of PPMN flame-retardant finishing in Example 3; (d) is a residual carbon of the cotton fabric with 40% weight gain of PPMN flame-retardant finishing in Example 4.

[0044] Figure 3 It is a residual carbon graph of the flame-retardant cotton fabric prepared in Examples 4, 6 and 8; wherein (a) is a residual carbon graph of pure cotton fabric; (b) is a residual carbon graph of the cotton fabric with 40% weight gain of PPMN flame-retardant finishing in Example 4; (c) is a residual carbon graph of the cotton fabric with 40% weight gain of PPMF flame-retardant finishing in Example 6; (d) is a residual carbon graph of the cotton fabric with 40% weight gain of PPML flame-retardant finishing in Example 8.

[0045] Figure 4 It is a residual carbon SEM graph of the flame-retardant cotton fabric prepared in Examples 4, 6 and 8; wherein (a) is a SEM graph of pure cotton fabric; (b) is a residual carbon SEM graph of the cotton fabric with 40% weight gain of PPMN flame-retardant finishing in Example 4; (c) is a residual carbon SEM graph of the cotton fabric with 40% weight gain of PPMF flame-retardant finishing in Example 6; (d) is a residual carbon SEM graph of the cotton fabric with 40% weight gain of PPML flame-retardant finishing in Example 8.

[0046] Figure 5 It is a residual carbon element distribution graph of the cotton fabric with 40% weight gain of PPMN flame-retardant finishing in Example 4; wherein (a) is C; (b) is O; (c) is N; (d) is P; (e) is Ni.

[0047] Figure 6 It is a residual carbon element distribution graph of the cotton fabric with 40% weight gain of PPMF flame-retardant finishing in Example 6; wherein (a) is C; (b) is O; (c) is N; (d) is P; (e) is Fe.

[0048] Figure 7 It is a residual carbon element distribution graph of the cotton fabric with 40% weight gain of PPML flame-retardant finishing in Example 8; wherein (a) is C; (b) is O; (c) is N; (d) is P; (e) is La.

[0049] Figure 8 The micro-entropy thermogravimetric, thermal gravimetric curves of the flame-retardant cotton fabric prepared in Examples 2-4 under nitrogen or air conditions; wherein, (a) the micro-entropy thermogravimetric curves of pure cotton fabric and the cotton fabric with different weight gain gradients of PPMN flame-retardant finishing under nitrogen conditions; (b) the thermal gravimetric curves of pure cotton fabric and the cotton fabric with different weight gain gradients of PPMN flame-retardant finishing under nitrogen conditions; (c) the micro-entropy thermogravimetric curves of pure cotton fabric and the cotton fabric with different weight gain gradients of PPMN flame-retardant finishing under air conditions; (d) the thermal gravimetric curves of pure cotton fabric and the cotton fabric with different weight gain gradients of PPMN flame-retardant finishing under air conditions.

[0050] Figure 9 The micro-entropy thermogravimetric, thermal gravimetric curves of the flame-retardant cotton fabric prepared in Examples 4, 6, 8 under nitrogen or air conditions; wherein, (a) the micro-entropy thermogravimetric curves of pure cotton fabric and the cotton fabric with 40% weight gain of PPMN, PPMF, PPML flame-retardant finishing under nitrogen conditions; (b) the thermal gravimetric curves of pure cotton fabric and the cotton fabric with 40% weight gain of PPMN, PPMF, PPML flame-retardant finishing under nitrogen conditions; (c) the micro-entropy thermogravimetric curves of pure cotton fabric and the cotton fabric with 40% weight gain of PPMN, PPMF, PPML flame-retardant finishing under air conditions; (d) the thermal gravimetric curves of pure cotton fabric and the cotton fabric with 40% weight gain of PPMN, PPMF, PPML flame-retardant finishing under air conditions.

[0051] Figure 10 The HRR, THR comparison charts of the flame-retardant cotton fabric prepared in Examples 2-4, 6, 8; wherein, (a) the HRR comparison chart of pure cotton fabric and the cotton fabric with different weight gain gradients of PPMN flame-retardant finishing in Examples 2-4; (b) the THR comparison chart of pure cotton fabric and the cotton fabric with different weight gain gradients of PPMN flame-retardant finishing in Examples 2-4; (c) the HRR comparison chart of pure cotton fabric and the cotton fabric with 40% weight gain of PPMN, PPMF, PPML flame-retardant finishing in Examples 4, 6, 8; (d) the THR comparison chart of pure cotton fabric and the cotton fabric with 40% weight gain of PPMN, PPMF, PPML flame-retardant finishing in Examples 4, 6, 8.

[0052] Figure 11 The specific optical density (Ds) comparison chart of the flame-retardant cotton fabric prepared in Examples 2-4 in smoke density test; wherein, (a) the specific optical density (Ds) comparison chart of pure cotton fabric and the cotton fabric with different weight gain gradients of PPMN flame-retardant finishing in Examples 2-4; (b) the specific optical density (Ds) comparison chart of pure cotton fabric and the cotton fabric with 40% weight gain of PPMN, PPMF, PPML flame-retardant finishing in Examples 4, 6, 8. DETAILED DESCRIPTION

[0053] The following examples further illustrate the technical solutions of the present application in detail, but are not used as limitations to the protection scope of the present application.

[0054] The preparation method of the phytic acid-g-PEG / melamine nickel complex flame retardant provided by the embodiment of the present application comprises the following steps:

[0055] Step 1. Add phytic acid into a three-necked flask, and slowly stir in an oil bath under a nitrogen atmosphere until no water droplets are generated at the gas outlet.

[0056] As a preferred solution, the stirring temperature is 135℃.

[0057] As a preferred solution, the stirring time is 2 hours.

[0058] As a preferred solution, the flow rate of nitrogen is 200 L / min.

[0059] Step 2. Add polyethylene glycol 200 into the three-necked flask to modify the phytic acid, and heat to obtain a black viscous product, i.e., the modified phytic acid (phytic acid-g-PEG).

[0060] As a preferred solution, the molar ratio of phytic acid to polyethylene glycol 200 is 1:3.

[0061] As a preferred solution, the reaction temperature is 135℃.

[0062] As a preferred solution, the reaction time is 5 hours.

[0063] Step 3. Add deionized water into the three-necked flask to fully dissolve the black viscous product obtained in step 2. After fully dissolving, add melamine into the three-necked flask to mix and react with the product obtained in step 2.

[0064] As a preferred solution, the ratio of phytic acid to deionized water is 0.01 mol:350 mL.

[0065] As a preferred solution, the molar ratio of phytic acid to melamine is 1:3.

[0066] As a preferred solution, the reaction temperature is 85℃.

[0067] As a preferred solution, the reaction time is 2 hours.

[0068] Step 4. Add sodium hydroxide into the three-necked flask, adjust the pH of the solution to neutral, and then add metal salts (nickel chloride, ferric chloride or lanthanum chloride) into the three-necked flask. After fully reacting, store the prepared solution product in a refrigerator to obtain a precipitate, centrifuge the precipitate, wash the precipitate obtained after centrifugation with deionized water, and dry to obtain the phytic acid-g-PEG / melamine metal complex flame retardant.

[0069] As a preferred solution, the pH is 7.

[0070] As a preferred solution, the molar ratio of phytic acid to metal salt is 1:3.

[0071] As a preferred solution, the reaction temperature is 85°C.

[0072] As a preferred solution, the reaction time is 1h.

[0073] The present application provides a method for preparing a flame-retardant cotton fabric, comprising the following steps:

[0074] Step 1. Place the cotton fabric in a sodium hydroxide solution, and after the end of the immersion, wash with deionized water and dry at room temperature.

[0075] As a preferred solution, the concentration of the sodium hydroxide solution is 2wt%.

[0076] As a preferred solution, the immersion temperature is 70°C.

[0077] As a preferred solution, the immersion time is 1h.

[0078] As a preferred solution, the bath ratio is 1:20.

[0079] Step 2. Immersing the cotton fabric in the phytic acid-g-PEG / melamine metal complex flame retardant solution prepared above, drying, and repeating the immersion and drying steps to obtain a cotton fabric with flame-retardant properties.

[0080] As a preferred solution, the concentration of the phytic acid-g-PEG / melamine metal complex flame retardant solution is 5wt%.

[0081] As a preferred solution, the immersion temperature is 40°C.

[0082] As a preferred solution, the immersion time is 10min.

[0083] As a preferred solution, the drying temperature is 70°C.

[0084] As a preferred solution, the bath ratio is 1:20.

[0085] As a preferred solution, the immersion-drying process is repeated to increase the weight of the cotton fabric by 10%-40%.

[0086] The present application will be further described below with reference to examples.

[0087] Example 1

[0088] A method for preparing a phytic acid-g-PEG / melamine metal complex flame retardant, comprising the following steps:

[0089] (1) Take 9.43 g of phytic acid solution (C6H 18 O 24 P6) (effective substance content 70%, Shanghai Aladdin Bio-Chem Technology Co., Ltd.) into a three-necked flask, fill nitrogen gas (200 L / min) in the oil bath at 135℃ until no liquid beads are formed at the gas outlet, and the time is 2 h.

[0090] (2) After the first step is completed, add 6 g of polyethylene glycol (HO(CH2CH2O) n H, Mn 200, Shanghai Aladdin Bio-Chem Technology Co., Ltd.) into the oil bath at 135℃ for 5 h to obtain modified phytic acid (phytic acid-g-PEG), and then cool the oil bath to 85℃, and add 350 ml of deionized water to obtain a phytic acid-g-PEG solution.

[0091] (3) Take 3.78 g of melamine (Shanghai Maikelin Biochemical Science and Technology Co., Ltd.) and add it into the phytic acid-g-PEG solution, mix uniformly, and perform hydrothermal reaction at 85℃ for 2 h to obtain a phytic acid-g-PEG / melamine solution.

[0092] (4) Adjust the pH of the phytic acid-g-PEG / melamine solution to neutral (7.0) using 2 mol / L sodium hydroxide solution, and then add 7.14 g of nickel chloride (Shanghai Maikelin Biochemical Science and Technology Co., Ltd.) into the solution, and react at 85℃ for 1 h. After the reaction is completed, place the reaction solution in a refrigeration room at a temperature of 5℃, and store for 12 h. After the supernatant and the precipitate are separated, centrifuge the precipitate, and then wash the precipitate after centrifugation with deionized water twice to obtain a solid product, which is a phytic acid-g-PEG / melamine nickel complex flame retardant (abbreviated as “PPMN”). Finally, move the precipitate to a beaker for refrigeration storage.

[0093] Example 2

[0094] A method for preparing a flame-retardant cotton fabric, comprising the following steps:

[0095] (1) Soak pure cotton fabric (abbreviated as “CT”) in a 2wt% sodium hydroxide solution (bath ratio 1:20) for pretreatment, the soaking temperature is 70℃, and the soaking time is 1 h. After the soaking is completed, wash with deionized water, and dry at room temperature.

[0096] (2) Prepare the PPMN flame retardant prepared in Example 1 into a solution with a mass fraction of 5wt%. Then, cut the cotton fabric according to different test requirements, and cut the cotton fabric according to different test requirements. The specific size of each test (SEM-EDS: 10×10 mm 2 , thermal gravimetric analysis (TGA) test: 2×2 mm 2Cone calorimeter test 100x100mm 2 Smoke density test: 75x75mm 2 Limiting oxygen index test: 150x58mm 2 Pure cotton fabric was immersed in the solution (bath ratio 1:20) and treated at 40°C for 10 min. The fabric was treated by repeated immersion-drying cycles, drying immediately after each immersion, until the sample mass reached the target weight gain threshold. The drying temperature was controlled at 70°C. The immersion-drying process was repeated several times until the cotton fabric gained 10% weight, obtaining a flame-retardant cotton fabric (abbreviated as "10% PPMN-CT").

[0097] Example 3

[0098] A method for preparing a flame-retardant coated cotton fabric, substantially the same as Example 2, except that the flame-retardant cotton fabric gained 20% weight, and other conditions remained unchanged, obtaining a flame-retardant cotton fabric (abbreviated as "20% PPMN-CT").

[0099] Example 4

[0100] A method for preparing a flame-retardant coated cotton fabric, substantially the same as Example 2, except that the flame-retardant cotton fabric gained 40% weight, and other conditions remained unchanged, obtaining a flame-retardant cotton fabric (abbreviated as "40% PPMN-CT").

[0101] Example 5

[0102] A method for preparing a phytic acid-g-PEG / melamine metal complex flame retardant, comprising the following steps:

[0103] (1) Take 9.43 g of phytic acid solution (C6H 18 O 24 P6) (effective substance content 70%, Shanghai Aladdin Biochemical Technology Co., Ltd.) and add it to a three-necked flask. In the oil bath at 135°C, nitrogen gas is filled (200 L / min) until no liquid beads form at the gas outlet, and the time is 2 h.

[0104] (2) After the first step is completed, 6 g of polyethylene glycol (HO(CH2CH2O) n H, Mn 200, Shanghai Aladdin Biochemical Technology Co., Ltd.) is added, and the reaction is carried out at 135°C for 5 h to obtain modified phytic acid (phytic acid-g-PEG). After the oil bath is cooled to 85°C, 350 ml of deionized water is added to obtain a phytic acid-g-PEG solution.

[0105] (3) 3.78 g of melamine (Shanghai Maikelin Biochemical Technology Co., Ltd.) was weighed and added into the phytic acid-g-PEG solution and mixed uniformly, and then hydrothermal reaction was carried out at 85°C for 2 h. After the reaction was sufficiently completed, the phytic acid-g-PEG / melamine solution formed was obtained.

[0106] (4) The pH of the phytic acid-g-PEG / melamine solution was adjusted to neutral (7.0) using 2 mol / L sodium hydroxide solution, and then 8.10 g of ferric chloride (Shanghai Maikelin Biochemical Technology Co., Ltd.) was added thereto, and reaction was carried out at 85°C for 1 h. After the reaction was completed, the reaction solution was allowed to stand, and was placed in a refrigeration room with a refrigeration temperature of 5°C, and was allowed to stand for 12 h. After the supernatant and the precipitate were separated, the precipitate was centrifuged, and then the precipitate after centrifugation was washed twice with deionized water to obtain a solid product, i.e., a phytic acid-g-PEG / melamine iron complex flame retardant (abbreviated as “PPMF”). Finally, the precipitate product was moved to a beaker for refrigeration storage.

[0107] Example 6

[0108] A method for preparing a flame-retardant cotton fabric, comprising the following steps:

[0109] (1) The pure cotton fabric (abbreviated as “CT”) was immersed in a 2 wt% sodium hydroxide solution (bath ratio 1:20) for pretreatment, the immersion temperature was 70°C, and the immersion time was 1 h. After immersion, the fabric was washed with deionized water and air-dried at room temperature.

[0110] (2) The PPMF flame retardant prepared in Example 5 was prepared into a solution with a mass fraction of 5 wt% using deionized water. Subsequently, the pure cotton fabric cut according to different test requirements (SEM-EDS: 10×10 mm 2 , thermogravimetric analysis (TGA) test: 2×2 mm 2 , cone calorimeter test 100×100 mm 2 ; smoke density test: 75×75 mm 2 , limiting oxygen index test: 150×58 mm 2 ) was immersed in the solution (bath ratio 1:20) at 40°C for 10 min. The fabric needs to be treated by cyclic immersion-drying, and drying is carried out immediately after each immersion until the mass of the sample reaches the target mass threshold. The drying temperature is controlled at 70°C. The above immersion-drying process needs to be repeated multiple times until the mass of the cotton fabric increases by 40%, and a flame-retardant cotton fabric (abbreviated as “40% PPMF-CT”) is obtained.

[0111] Example 7

[0112] A preparation method of a phytic acid-g-PEG / melamine metal complex flame retardant, comprising the following steps:

[0113] (1) 9.43 g of a phytic acid solution (C6H 18 O 24 P6) (solution content 70%, Shanghai Aladdin Bio-Chem Technology Co., Ltd.) was added to a three-necked flask, and nitrogen gas (200 L / min) was filled in an oil bath at 135°C until no liquid beads were formed at the gas outlet, and the time was 2 h.

[0114] (2) After the first step was completed, 6 g of polyethylene glycol (HO(CH2CH2O) n H, Mn 200), Shanghai Aladdin Bio-Chem Technology Co., Ltd.) was added, and the reaction was carried out in an oil bath at 135°C for 5 h; the modified phytic acid (phytic acid-g-PEG) was obtained, and after the oil bath was cooled to 85°C, 350 ml of deionized water was added to obtain a phytic acid-g-PEG solution.

[0115] (3) 3.78 g of melamine (Shanghai Maikelin Biochemical Technology Co., Ltd.) was added to the phytic acid-g-PEG solution and mixed uniformly, and a hydrothermal reaction was carried out at 85°C for 2 h; after the reaction was completed, the phytic acid-g-PEG / melamine solution was obtained.

[0116] (4) The pH of the phytic acid-g-PEG / melamine solution was adjusted to neutral (7.0) using a 2 mol / L sodium hydroxide solution, and then 11.14 g of lanthanum chloride (Shanghai Maikelin Biochemical Technology Co., Ltd.) was added, and the reaction was carried out at 85°C for 1 h; after the reaction was completed, the reaction solution was placed in a refrigerator at a cold storage temperature of 5°C and was cold stored for 12 h; after the supernatant and the precipitate were separated, the precipitate was centrifuged, and then the precipitate after centrifugation was washed with deionized water twice to obtain a solid product, which was a phytic acid-g-PEG / melamine lanthanum complex flame retardant (abbreviated as "PPML"); finally, the precipitate was moved to a beaker for cold storage.

[0117] Example 8

[0118] A preparation method of a flame-retardant cotton fabric, comprising the following steps:

[0119] (1) The pure cotton fabric (abbreviated as "CT") was soaked in a 2 wt% sodium hydroxide solution (bath ratio 1:20) for pretreatment, the soaking temperature was 70°C, and the soaking time was 1 h; after soaking, the cotton fabric was washed with deionized water and was air-dried at room temperature.

[0120] (2) The PPML flame retardant prepared in Example 7 was formulated into a solution with a mass fraction of 5wt% using deionized water. Subsequently, cotton fabrics were cut according to different test requirements, and pure cotton fabrics with specific sizes (SEM-EDS: 10x10mm 2 , Thermogravimetric analysis (TGA) test: 2x2mm 2 , Cone calorimeter test 100x100mm 2 ; Smoke density test: 75x75mm 2 , Limiting oxygen index test: 150x58mm 2 ) were immersed in the solution (bath ratio 1:20) and treated at 40°C for 10min. The fabric needs to be treated by repeated immersion-drying, and drying is carried out immediately after each immersion until the sample mass reaches the target weight threshold. The drying temperature is controlled at 70°C. The above immersion-drying process needs to be repeated multiple times until the cotton fabric increases by 40%, and the flame-retardant cotton fabric (abbreviated as "40%PPML-CT") is obtained.

[0121] Example 9

[0122] The flame-retardant cotton fabrics prepared in the above examples were tested and the results were analyzed.

[0123] 1. Test method

[0124] SEM-EDS analysis: After burning, the residual carbon of pure cotton fabric and flame-retardant cotton fabric was selected and attached to conductive glue, and then gold plating was performed. The microstructure was observed by scanning electron microscope, and the contents and distribution of C, O, N, P, Ni, Fe, and La on the surface of PPMN-CT, PPMF-CT, and PPML-CT were detected by energy dispersive spectrometer.

[0125] Thermogravimetric analysis (TGA) test: The thermal stability and thermal oxidative stability of the flame retardant and flame-retardant fabric samples were tested. The sample mass was about 4mg, and the size was 2x2mm 2 , and the temperature was raised from room temperature to 800°C at a rate of 10°C / min under nitrogen and air atmospheres, respectively.

[0126] Cone calorimeter test: The CCT of the fabric sample was according to ISO5660 standard, and the sample size was 100x100mm 2 , 3 pieces were stacked together and placed in aluminum foil, and the foam coating side and the back side were randomly discharged. The heat flux of the test was 35kW·m -2 .

[0127] Smoke density test: The smoke density of the fabric sample was according to ISO 5659 standard, and the sample size was 75x75mm 2 , 3 pieces were stacked together and placed in aluminum foil. The heat flux of the test was 25kW·m -2Flameless condition.

[0128] Test of limiting oxygen index: According to GB / T 5454 1997 Textiles-determination of burning behavior-ignition time and heat release, five pieces of flame-retardant cotton fabric were prepared, and the sample size was about 150×58 mm 2 The minimum oxygen concentration value required to maintain combustion in an oxygen-nitrogen mixed gas stream is expressed in percentage.

[0129] 2. Results analysis

[0130] (1) Flow chart

[0131] Figure 1 The complete process of synthesis of phytic acid-based flame retardant and cotton fabric finishing process is shown. Through the esterification modification of phytic acid (PA) by polyethylene glycol 200 (PEG200), the gas source action of melamine (MEL) and the synergistic cooperation of metal ions, a stable flame retardant system is formed. The impregnation process makes the flame retardant uniformly loaded on the surface and inside of the cotton fiber through repeated treatment, and the process design is simple and controllable, which is suitable for large-scale production.

[0132] (2) Carbon residue analysis

[0133] Based on Figure 2 , the residual carbon rate of pure cotton fabric (CT) without flame retardant treatment after burning is less than 5wt%, and the fiber structure is completely destroyed; while the residual carbon content of the flame-retardant treated cotton fabric increases significantly with the weight gain rate, and the 40wt% gain sample has a residual carbon structure of 51.6wt%. The 40wt% gain sample forms a physical heat insulation layer, effectively blocking the transfer of heat and oxygen, and the oxygen index (LOI) increases to 30.5wt% (Table 1), which verifies the condensed phase flame retardant mechanism. The flame retardant promotes the dehydration and carbonization of cellulose to form a stable carbon layer, inhibiting the spread of flame.

[0134] (3) Scanning electron microscope (SEM) analysis

[0135] Based on Figure 4 , the fibers of pure cotton fabric melt and break after burning, and the structure collapses; while the residual carbon of 40wt% gain flame-retardant cotton fabric (PPMN-CT, PPMF-CT, PPML-CT) still maintains the complete weaving structure, and the fiber profile is clear, indicating that the flame retardant promotes the formation of a dense carbon layer during the burning process.

[0136] (4) EDS element analysis

[0137] Based on Figure 5, 6, 7, EDS element mapping showed that C, O, N, P and metal ions (Ni, Fe, La) were uniformly distributed in the residual carbon, confirming the effective loading and dispersion of the flame retardant in the matrix. At the same time, it also showed that the flame retardant played a good synergistic flame-retardant effect in the combustion process, promoting the uniform formation of the carbon layer, thereby effectively improving the flame-retardant performance of the cotton fabric

[0138] (5) Thermal stability (TGA) analysis

[0139] Based on Figure 8 , 9, thermogravimetric analysis (TGA) showed that the flame-retardant cotton fabric exhibited significant improvement in thermal stability under both air and nitrogen conditions. Under air conditions, the carbon residue rate at 500°C reached 25wt% (pure cotton fabric was almost completely decomposed), and there was still 7.7% residual at 800°C; under nitrogen conditions, the carbon residue rate at 800°C increased from 5.0% of pure cotton to 22.1%. In summary, the phytic acid-based flame retardant significantly improved the thermal stability and flame-retardant performance of the cotton fabric through multi-component synergistic effect (catalytic carbonization, gas expansion, metal stabilization). The PPMN flame-retardant treated cotton fabric exhibited the best performance at high temperature due to its efficient catalytic and barrier effect. This technology provides important theoretical support for the development of environmentally friendly and efficient biomass flame-retardant materials.

[0140] (6) Cone calorimeter (CCT) analysis

[0141] Based on Figure 10 , cone calorimeter (CCT) testing showed that the heat release rate (HRR) decreased from 268.3kW / m 2 to 101.8kW / m 2 (62wt% reduction), and the total heat release (THR) decreased from 11.6MJ / m 2 to 7.2MJ / m 2 (37.5wt% reduction). This significant change indicates that flame retardant treatment can effectively reduce the heat release rate of the material, thereby significantly improving its flame-retardant performance.

[0142] (7) Smoke density analysis

[0143] Based on Figure 11 , the optical density of pure cotton fabric was 154.1, while the optical density of the 40% weight gain flame-retardant cotton fabric (PPMN-CT) decreased to 84.3 (45.3% reduction). The inert gas (such as NH3) produced by the decomposition of melamine dilutes the flammable gas, and the metal ions (such as Ni 2 +) inhibit the formation of smoke particles, significantly reducing the release of toxic smoke and improving fire safety.

[0144] (8) Limiting oxygen index (LOI) analysis

[0145] Table 1 Limiting oxygen index

[0146]

[0147]

[0148] Based on Table 1, the LOI of pure cotton fabric is 18.0% (flammable material), after flame-retardant finishing, the LOI value increases with the increase of weight percentage, and the LOI of the cotton fabric doped with metal nickel flame retardant reaches 30.5% (difficult flammable material) when the weight percentage is 40%. Among different metal ion doped samples, the LOI of the sample doped with metal nickel flame retardant (40% PPMN-CT) is the highest (30.5%), followed by the sample doped with metal iron (22.8%) and the sample doped with metal lanthanum (24%), which indicates that the type of metal ion has a significant effect on the flame-retardant performance. The catalytic carbonization ability of nickel ion is the strongest, which cooperates with the gas source effect of melamine to form a more efficient flame-retardant system.

Claims

1. A method for preparing a phytic acid-based flame retardant, characterized in that: Includes the following: Step 1. Phytic acid is stirred under a nitrogen atmosphere until no water droplets are produced at the gas outlet, thereby obtaining treated phytic acid; Step 2. adding polyethylene glycol to the treated phytic acid obtained in step 1, heating the mixture for reaction, and obtaining modified phytic acid; Step 3. dissolving the modified phytic acid obtained in step 2 in deionized water, adding melamine, and performing a hydrothermal reaction to obtain a modified phytic acid / melamine solution; Step 4. After adjusting the pH of the modified phytic acid / melamine solution obtained in step 3 to neutral using an alkaline solution, a metal salt is added. After sufficient reaction, the prepared solution product is refrigerated and allowed to stand to obtain a precipitated product. The precipitate is centrifuged, and the precipitated product after centrifugation is washed and dried to obtain a phytic acid-based flame retardant; wherein the metal salt is at least one of nickel chloride, ferric chloride and lanthanum chloride.

2. The preparation method according to claim 1, characterized in that In step 1, the stirring temperature is 130-150° C., the stirring time is 1-2 h, and the nitrogen flow rate is 200-400 L / min.

3. The preparation method according to claim 1, characterized in that In step 2, the molar ratio of phytic acid to polyethylene glycol is 1:3-6, the reaction temperature is 130-150° C., and the reaction time is 4-5 hours.

4. The preparation method according to claim 1, characterized in that In step 3, the molar ratio of phytic acid to melamine is 1:3-6, the reaction temperature is 80-90° C., and the reaction time is 2-3 h.

5. The preparation method according to claim 1, characterized in that In step 4, the molar ratio of phytic acid to metal salt is 1:3-6, the reaction temperature is 80-90° C., and the reaction time is 0.5-1 h; the refrigeration temperature is 0-5° C., and the standing time is 10-18 h; and the washing is performed with deionized water.

6. A phytic acid-based flame retardant prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the phytic acid-based flame retardant according to claim 6 in the preparation of flame-retardant cotton fabrics.

8. A method for preparing a flame retardant cotton fabric, characterized in that: The steps include: The cotton fabric is immersed in the phytic acid flame retardant solution of claim 6 for finishing treatment and then dried to obtain the cotton fabric with flame retardant properties.

9. The preparation method according to claim 8, characterized in that The concentration of the phytic acid-based flame retardant solution is 5wt%-20wt%, the immersion temperature is 40-60℃, the immersion time is 1-10min, the bath ratio is 1:20-40; the drying temperature is 60-80℃; the immersion and drying are repeated for many times until the cotton fabric increases in weight by 10%-40%.

10. The preparation method according to claim 8, characterized in that Before finishing, cotton fabric needs to be pretreated. The pretreatment method comprises the following steps: immersing the cotton fabric in an alkali solution for pretreatment, washing the cotton fabric with deionized water after immersion, and air-drying the pretreated cotton fabric at room temperature. The alkali solution is a sodium hydroxide solution, the concentration of the pretreatment alkali solution is 1 wt%-10 wt%, the immersion temperature is 70-90°C, the immersion time is 1-2 hours, and the bath ratio is 1:20-40.

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