High-flame-retardant anti-dripping fiber and preparation method thereof

Abstract

The invention provides a high-flame-retardant anti-dripping fiber and a preparation method thereof, and belongs to the technical field of flame-retardant high polymer materials. The preparation method comprises the following steps: carrying out a reaction on modified polylactic acid, a boric acid-based phosphorus-nitrogen flame retardant and a first catalyst according to a weight ratio of (35-40): (4-6): (0.062-0.075) to obtain a compound, carrying out a reaction on acrylonitrile, eugenol, glycidyl methacrylate, sodium thiocyanate and azodiisobutyronitrile according to a weight ratio of (10-15): (0.1-0.2): (0.5-0.8): (7-8): (0.065-0.075) to obtain modified polyacrylonitrile, and carrying out a reaction on the modified polyacrylonitrile and the boric acid-based phosphorus-nitrogen flame retardant and the first catalyst according to a weight ratio of (10-15): (0.1 the modified polyacrylonitrile and the compound are sequentially subjected to melt blending and melt spinning according to the weight ratio of (20-25): (50-65), and the high-flame-retardant anti-dripping fiber is prepared. Phosphorus, nitrogen and boron generate a synergistic effect, combustion is inhibited through dual mechanisms of a gas phase and a condensed phase, and a good flame retardant effect is achieved; the ring-opening cross-linking reaction of the epoxy group in the modified polyacrylonitrile and the hydroxyl group in the compound is combined with the hydrogen-bond interaction to form a cross-linked network, so that the generation of molten drops is inhibited.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flame-retardant high polymer materials, and particularly relates to a high flame-retardant and anti-dripping fiber and a preparation method thereof. BACKGROUND

[0002] In modern society, the demand for fiber materials in the fields of textiles, decorative materials and industrial fiber products continues to grow. However, traditional fiber materials often burn rapidly due to poor flame retardant performance when encountering fire, not only causing property losses, but also causing secondary fires due to the phenomenon of dripping, exacerbating the spread of fire and posing a serious threat to people's life safety. Dripping not only spreads the flame to other areas, but also its high temperature characteristics can scald personnel, causing great harm, which makes it urgent to develop fiber materials with high flame retardant performance and effective inhibition of dripping.

[0003] Although existing flame-retardant fiber technology has made some progress, there are still many limitations. The stability of some flame retardants in fibers is poor, and after multiple washes, the flame retardant effect will decrease significantly, making it difficult to meet long-term use requirements; some flame-retardant fibers only inhibit combustion through a single mechanism, have low flame retardant efficiency, and cannot play an ideal role in complex fire environments; some fibers have certain flame retardancy, but still melt and flow significantly at high temperatures, cannot effectively prevent dripping, and are difficult to meet strict fire safety standards.

[0004] Chinese Patent CN 111848893B discloses a phosphorus-nitrogen intumescent flame retardant, its preparation and application in polylactic acid, wherein the flame retardant is a copolymer of vanillin and phenylphosphoryl dichloride. Although the phosphorus-nitrogen intumescent flame retardant contains a bio-based component and is relatively simple to prepare, it has poor flame retardant efficiency and is prone to dripping when applied to flame-retardant polylactic acid.

[0005] Therefore, it is an important problem to be solved in the field to provide a fiber material with high efficient flame retardant and anti-dripping. SUMMARY

[0006] To solve the problems in the prior art, the present application provides a high flame-retardant and anti-dripping fiber and a preparation method thereof. Specifically, the technical solution of the present application includes the following contents:

[0007] A preparation method of a high flame-retardant and anti-dripping fiber includes the following steps:

[0008] The modified polylactic acid, the boric acid-based phosphorus-nitrogen flame retardant and the first catalyst are reacted in a weight ratio of 35-40:4-6:0.062-0.075 to obtain a composite, acrylonitrile, eugenol, glycidyl methacrylate, sodium thiocyanate and azobisisobutyronitrile are reacted in a weight ratio of 10-15:0.1-0.2:0.5-0.8:7-8:0.065-0.075 to obtain a modified polyacrylonitrile, and the modified polyacrylonitrile and the composite are sequentially melt blended and melt spun in a weight ratio of 20-25:50-65 to obtain the high-flame-retardant melt-dripping-resistant fiber.

[0009] Further, the preparation method of the modified polylactic acid comprises the following steps:

[0010] After 30-40 parts by weight of lactic acid is subjected to a prepolymerization reaction to obtain a prepolymer, 2-3 parts by weight of succinic anhydride and 0.3-0.4 parts by weight of a second catalyst are added to react to obtain a carboxyl-terminated polylactic acid, and 20-30 parts by weight of the carboxyl-terminated polylactic acid, 0.5-1.2 parts by weight of sorbitol and 0.25-0.38 parts by weight of a third catalyst are reacted to obtain the modified polylactic acid.

[0011] Further, the prepolymerization reaction is carried out at a temperature of 100-120℃ for 2-3 hours.

[0012] Further, the second catalyst is stannous octoate.

[0013] Further, the reaction of the lactic acid, the succinic anhydride and the second catalyst is carried out at a temperature of 145-155℃ for 6-8 hours.

[0014] Further, the third catalyst is 4-dimethylaminopyridine.

[0015] Further, the reaction of the carboxyl-terminated polylactic acid, the sorbitol and the third catalyst is carried out at a temperature of 55-65℃ for 8-10 hours.

[0016] Further, the preparation method of the boric acid-based phosphorus-nitrogen flame retardant comprises the following steps:

[0017] Phosphorus oxychloride and anhydrous ethanol are reacted in a weight ratio of 15-18:9-11 to obtain an intermediate product, 3,4-dimethylphenylboronic acid, diethylenetriamine and formaldehyde are reacted in a weight ratio of 15-17:10-12:2.8-3.2 to obtain aminoboronic acid, and the aminoboronic acid, the intermediate product, triethylamine and a fourth catalyst are reacted in a weight ratio of 35-40:26-30:40-55:0.23-0.26 to obtain the boric acid-based phosphorus-nitrogen flame retardant.

[0018] Further, the reaction of the phosphorus oxychloride and the anhydrous ethanol is carried out at 0-5℃ for 4-5 hours, and then the temperature is raised to 23-25℃ for 6-8 hours.

[0019] Further, the reaction conditions of the 3,4-dimethylphenylboronic acid, diethylene triamine and formaldehyde include that the reaction pH is 9-11, the reaction temperature is 45-55℃ and the reaction time is 4-5h.

[0020] Further, the fourth catalyst is copper chloride.

[0021] Further, the reaction conditions of the aminated phenylboronic acid, the intermediate product, triethylamine and the fourth catalyst are that the reaction is carried out at 0-5℃ for 6-7h, and then the temperature is increased to 23-25℃ and the reaction is carried out for 18-20h.

[0022] Further, the first catalyst is p-toluenesulfonic acid.

[0023] Further, the reaction conditions of the modified polylactic acid, the borate-based phosphorus-nitrogen flame retardant and the first catalyst include that the reaction temperature is 145-155℃ and the reaction time is 2-3h.

[0024] Further, the sodium thiocyanate is a 50% sodium thiocyanate solution by mass fraction.

[0025] Further, the reaction conditions of the acrylonitrile, eugenol, glycidyl methacrylate, sodium thiocyanate and azobisisobutyronitrile include that the reaction temperature is 65-75℃ and the reaction time is 5-6h.

[0026] Further, the melt blending conditions of the modified polyacrylonitrile and the composite include that the blending temperature is 200-220℃ and the blending time is 10-20min.

[0027] Further, the melt spinning conditions of the modified polyacrylonitrile and the composite include that the spinning temperature is 195-220℃, the side blowing temperature is 24-27℃ and the cooling air speed is 0.4-0.6m / s.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] (1) The hydroxyl group in anhydrous ethanol is substituted with the chlorine atom in phosphorus oxychloride to obtain an intermediate product, 3,4-dimethylphenylboronic acid, diethylenetriamine and formaldehyde are subjected to Mannich reaction to graft diethylenetriamine onto the benzene ring to obtain aminated phenylboronic acid, the amino group in the aminated phenylboronic acid is substituted with the chlorine atom in the intermediate product to obtain a borate phosphorus-nitrogen flame retardant; butanedioic anhydride is subjected to polycondensation with lactic acid to obtain carboxyl-terminated polylactic acid, the carboxyl-terminated polylactic acid is subjected to esterification with sorbitol to obtain modified polylactic acid; acrylonitrile, eugenol and glycidyl methacrylate are subjected to polycondensation to obtain modified polyacrylonitrile; the hydroxyl group in the modified polylactic acid is dehydrated and condensed with the borate group in the borate phosphorus-nitrogen flame retardant to form a reversible borate ester bond to obtain a complex, and in the melting process, the hydroxyl group in the modified polyacrylonitrile is hydrogen-bonded with the carbonyl group in the complex, and the epoxy group in the modified polyacrylonitrile is ring-opening reacted with the hydroxyl group in the complex to prepare a high-flame-retardant melt-drip-resistant fiber.

[0030] (2) In the present application, phosphorus, nitrogen and boron form a synergistic effect, which can inhibit combustion through both gas phase and condensed phase mechanisms to form good flame-retardant effect; during combustion, the phosphorus-nitrogen system promotes the formation of a dense carbon layer to isolate oxygen and heat, and the borate group enhances the stability of the carbon layer to reduce melt dripping and smoke release; the ring-opening crosslinking reaction of the epoxy group in the modified polyacrylonitrile and the hydroxyl group in the complex, combined with hydrogen bonding, further forms a crosslinking network to inhibit high-temperature melting flow.

[0031] (3) The high-flame-retardant melt-drip-resistant fiber prepared in the present application has better water washing resistance through chemical bonding of the borate phosphorus-nitrogen flame retardant in the fiber; the reversible borate ester bond between the modified polylactic acid and the borate phosphorus-nitrogen flame retardant will undergo dynamic reorganization during high-temperature combustion, further inhibiting the generation of melt dripping. DETAILED DESCRIPTION

[0032] The technical solutions of the present application will be clearly and completely described below through examples of the present application. Obviously, the described examples are only a part of the examples of the present application, rather than all the examples. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0033] Unless otherwise specified, the raw materials and reagents used in the present application below are commercially available or can be prepared by known methods.

[0034] Preparation Example 1:

[0035] The preparation method of the modified polylactic acid comprises the following steps:

[0036] 30 parts by weight of lactic acid is placed in an environment with a pressure of 0.096 MPa, heated to 100°C and stirred for 2 hours to obtain a prepolymer, then 2 parts by weight of succinic anhydride and 0.3 parts by weight of stannous octoate are added, and stirred at 145°C for 6 hours to obtain carboxyl-terminated polylactic acid; 20 parts by weight of carboxyl-terminated polylactic acid, 0.5 parts by weight of sorbitol and 0.25 parts by weight of 4-dimethylaminopyridine are dispersed in 100 parts by weight of mixed solvent (V 二氯甲烷 : V N,N-二甲基甲酰胺 = 4: 1), stirred at 55°C for 8 hours in a nitrogen environment, and after the reaction is completed, centrifuged, washed and vacuum dried in sequence to obtain modified polylactic acid.

[0037] Preparation Example 2:

[0038] A method for preparing modified polylactic acid, comprising the following steps:

[0039] 32 parts by weight of lactic acid is placed in an environment with a pressure of 0.097 MPa, heated to 105°C and stirred for 2.2 hours to obtain a prepolymer, then 2.2 parts by weight of succinic anhydride and 0.32 parts by weight of stannous octoate are added, and stirred at 147°C for 6.5 hours to obtain carboxyl-terminated polylactic acid; 22 parts by weight of carboxyl-terminated polylactic acid, 0.7 parts by weight of sorbitol and 0.27 parts by weight of 4-dimethylaminopyridine are dispersed in 100 parts by weight of mixed solvent (V 二氯甲烷 : V N,N-二甲基甲酰胺 = 4: 1), stirred at 57°C for 8.5 hours in a nitrogen environment, and after the reaction is completed, centrifuged, washed and vacuum dried in sequence to obtain modified polylactic acid.

[0040] Preparation Example 3:

[0041] A method for preparing modified polylactic acid, comprising the following steps:

[0042] 34 parts by weight of lactic acid is placed in an environment with a pressure of 0.097 MPa, heated to 110°C and stirred for 2.4 hours to obtain a prepolymer, then 2.5 parts by weight of succinic anhydride and 0.35 parts by weight of stannous octoate are added, and stirred at 148°C for 7 hours to obtain carboxyl-terminated polylactic acid; 25 parts by weight of carboxyl-terminated polylactic acid, 0.8 parts by weight of sorbitol and 0.30 parts by weight of 4-dimethylaminopyridine are dispersed in 100 parts by weight of mixed solvent (V 二氯甲烷 : V N,N-二甲基甲酰胺 = 4: 1), stirred at 59°C for 9 hours in a nitrogen environment, and after the reaction is completed, centrifuged, washed and vacuum dried in sequence to obtain modified polylactic acid.

[0043] Preparation Example 4:

[0044] A method for preparing modified polylactic acid, comprising the following steps:

[0045] 38 parts by weight of lactic acid is placed in an environment with a pressure of 0.098 MPa, heated to 115°C and stirred for 2.8 hours to obtain a prepolymer, then 2.8 parts by weight of succinic anhydride and 0.37 parts by weight of stannous octoate are added, and stirred at 151°C for 7.5 hours to obtain carboxyl-terminated polylactic acid; 28 parts by weight of carboxyl-terminated polylactic acid, 1.0 part by weight of sorbitol and 0.34 part by weight of 4-dimethylaminopyridine are dispersed in 100 parts by weight of mixed solvent (V 二氯甲烷 :V N,N-二甲基甲酰胺 = 4: 1), stirred at 62°C for 9.5 hours in a nitrogen environment, and after the reaction is completed, centrifuged, washed and vacuum dried in sequence to obtain modified polylactic acid.

[0046] Preparation Example 5:

[0047] A method for preparing modified polylactic acid, comprising the following steps:

[0048] 40 parts by weight of lactic acid is placed in an environment with a pressure of 0.098 MPa, heated to 120°C and stirred for 3 hours to obtain a prepolymer, then 3 parts by weight of succinic anhydride and 0.4 parts by weight of stannous octoate are added, and stirred at 155°C for 8 hours to obtain carboxyl-terminated polylactic acid; 30 parts by weight of carboxyl-terminated polylactic acid, 1.2 parts by weight of sorbitol and 0.38 parts by weight of 4-dimethylaminopyridine are dispersed in 100 parts by weight of mixed solvent (V 二氯甲烷 :V N,N-二甲基甲酰胺 = 4: 1), stirred at 65°C for 10 hours in a nitrogen environment, and after the reaction is completed, centrifuged, washed and vacuum dried in sequence to obtain modified polylactic acid.

[0049] Preparation Example 6:

[0050] A method for preparing modified polylactic acid, comprising the following steps:

[0051] 40 parts by weight of lactic acid is placed in an environment with a pressure of 0.098 MPa, heated to 120°C and stirred for 3 hours to obtain a prepolymer, then 3 parts by weight of succinic anhydride and 0.4 parts by weight of stannous octoate are added, and stirred at 155°C for 8 hours to obtain carboxyl-terminated polylactic acid; 30 parts by weight of carboxyl-terminated polylactic acid, 1.2 parts by weight of sorbitol and 0.38 parts by weight of 4-dimethylaminopyridine are dispersed in 100 parts by weight of mixed solvent (V 二氯甲烷 :V N,N-二甲基甲酰胺 = 4: 1), stirred at 65°C for 10 hours in a nitrogen environment, and after the reaction is completed, centrifuged, washed and vacuum dried in sequence to obtain modified polylactic acid.

[0052] Preparation Example 7:

[0053] A method for preparing modified polylactic acid, comprising the following steps:

[0054] 40 parts by weight of lactic acid is placed in a pressure environment with a pressure of 0.098 MPa, heated to 120°C and stirred for 3 hours to obtain a prepolymer, then 3 parts by weight of succinic anhydride and 0.4 parts by weight of stannous octoate are added, and stirred at 155°C for 8 hours to obtain a carboxyl-terminated polylactic acid; 30 parts by weight of carboxyl-terminated polylactic acid, 1.2 parts by weight of 1,3-butanediol and 0.38 parts by weight of 4-dimethylaminopyridine are dispersed in 100 parts by weight of mixed solvent (V 二氯甲烷 :V N,N-二甲基甲酰胺 = 4: 1) at 65°C under nitrogen protection environment for 10 hours, and then centrifuged, washed and vacuum dried to obtain modified polylactic acid.

[0055] Preparation Example 8:

[0056] A method for preparing polylactic acid, comprising the following steps:

[0057] 40 parts by weight of lactic acid is placed in a pressure environment with a pressure of 0.098 MPa, heated to 120°C and stirred for 3 hours to obtain a prepolymer, then 3 parts by weight of succinic anhydride and 0.4 parts by weight of stannous octoate are added, and stirred at 155°C for 8 hours to obtain a carboxyl-terminated polylactic acid; 30 parts by weight of carboxyl-terminated polylactic acid, 1.2 parts by weight of 1,3-butanediol and 0.38 parts by weight of 4-dimethylaminopyridine are dispersed in 100 parts by weight of mixed solvent (V

[0058] Preparation Example 9:

[0059] A method for preparing a borate-based phosphorus-nitrogen flame retardant, comprising the following steps:

[0060] 15 parts by weight of phosphorus oxychloride is dispersed in 9 parts by weight of anhydrous ethanol, stirred at 0°C for 4 hours, then heated to 23°C and stirred for 6 hours, and then vacuum distilled to obtain an intermediate product; 15 parts by weight of 3,4-dimethylphenylboronic acid and 10 parts by weight of diethylenetriamine are dispersed in 500 parts by weight of deionized water to adjust the pH to 9, then 2.8 parts by weight of formaldehyde is added, and stirred at 45°C for 4 hours, and then precipitated with isopropyl alcohol, centrifuged at a speed of 9000 r / min for 10 minutes, and then vacuum dried to obtain aminoboronic acid; 35 parts by weight of aminoboronic acid, 40 parts by weight of triethylamine and 0.23 parts by weight of copper chloride are dispersed in 200 parts by weight of N,N-dimethylformamide, and 26 parts by weight of the intermediate product is slowly added dropwise, stirred at 0°C for 6 hours, then heated to 23°C and stirred for 18 hours, and then filtered, washed and vacuum dried to obtain a borate-based phosphorus-nitrogen flame retardant.

[0061] Preparation Example 10:

[0062] The preparation method of the boron-based phosphorus-nitrogen flame retardant comprises the following steps: 16 parts by weight of phosphorus oxychloride is dispersed in 9.5 parts by weight of anhydrous ethanol, stirred at 1℃ for 4.2 hours, then the temperature is raised to 24℃ and stirred for 6.5 hours, after the reaction is completed, vacuum distillation is performed to obtain an intermediate product; 15.5 parts by weight of 3,4-dimethylphenyl boronic acid and 10.5 parts by weight of diethylenetriamine are dispersed in 500 parts by weight of deionized water, the pH is adjusted to 9.5, then 2.9 parts by weight of formaldehyde is added, and the mixture is stirred at 47℃ for 4.2 hours, after the reaction is completed, isopropanol is used for precipitation, centrifugation is performed at a speed of 9000 r / min for 10 minutes, and then vacuum drying is performed to obtain aminoboronic acid; 36 parts by weight of aminoboronic acid, 43 parts by weight of triethylamine and 0.24 parts by weight of copper chloride are dispersed in 200 parts by weight of N,N-dimethylformamide, 27 parts by weight of the intermediate product is slowly added dropwise, stirred at 1℃ for 6.2 hours, then the temperature is raised to 24℃ and stirred for 18.5 hours, after the reaction is completed, filtration, washing and vacuum drying are sequentially performed to obtain the boron-based phosphorus-nitrogen flame retardant.

[0063] Preparation Example 11:

[0064] The preparation method of the boron-based phosphorus-nitrogen flame retardant comprises the following steps:

[0065] 17 parts by weight of phosphorus oxychloride is dispersed in 10 parts by weight of anhydrous ethanol, stirred at 3℃ for 4.5 hours, then the temperature is raised to 25℃ and stirred for 7 hours, after the reaction is completed, vacuum distillation is performed to obtain an intermediate product; 16 parts by weight of 3,4-dimethylphenyl boronic acid and 11 parts by weight of diethylenetriamine are dispersed in 500 parts by weight of deionized water, the pH is adjusted to 10, then 3.0 parts by weight of formaldehyde is added, and the mixture is stirred at 49℃ for 4.5 hours, after the reaction is completed, isopropanol is used for precipitation, centrifugation is performed at a speed of 9000 r / min for 10 minutes, and then vacuum drying is performed to obtain aminoboronic acid; 37 parts by weight of aminoboronic acid, 47 parts by weight of triethylamine and 0.25 parts by weight of copper chloride are dispersed in 200 parts by weight of N,N-dimethylformamide, 28 parts by weight of the intermediate product is slowly added dropwise, stirred at 3℃ for 6.7 hours, then the temperature is raised to 23℃ and stirred for 19.5 hours, after the reaction is completed, filtration, washing and vacuum drying are sequentially performed to obtain the boron-based phosphorus-nitrogen flame retardant.

[0066] Preparation Example 12:

[0067] The preparation method of the boron-based phosphorus-nitrogen flame retardant comprises the following steps:

[0068] 17 parts by weight of phosphorus oxychloride were dispersed in 10.5 parts by weight of anhydrous ethanol, after stirring at 4°C for 4.8 hours, the temperature was raised to 25°C and stirring was continued for 7.5 hours, after the reaction was completed, vacuum distillation was carried out to obtain an intermediate product; 16.5 parts by weight of 3,4-dimethylphenylboronic acid and 11.5 parts by weight of diethylenetriamine were dispersed in 500 parts by weight of deionized water, and the pH was adjusted to 10, then 3.1 parts by weight of formaldehyde was added, and stirring was carried out at 52°C for 4.7 hours, after the reaction was completed, isopropyl alcohol was used for precipitation, centrifugation was carried out at a speed of 9000 r / min for 10 minutes, and vacuum drying was carried out to obtain aminoboronic acid; 38 parts by weight of aminoboronic acid, 50 parts by weight of triethylamine and 0.25 parts by weight of copper chloride were dispersed in 200 parts by weight of N,N-dimethylformamide, 29 parts by weight of the intermediate product was slowly added dropwise, stirring was carried out at 3°C for 6.8 hours, then the temperature was raised to 25°C and stirring was continued for 19.5 hours, after the reaction was completed, filtration, washing and vacuum drying were carried out in sequence to obtain a boronic acid-based phosphorus-nitrogen flame retardant.

[0069] Preparation Example 13:

[0070] The preparation method of the boronic acid-based phosphorus-nitrogen flame retardant comprises the following steps:

[0071] 18 parts by weight of phosphorus oxychloride were dispersed in 11 parts by weight of anhydrous ethanol, after stirring at 5°C for 5 hours, the temperature was raised to 25°C and stirring was continued for 8 hours, after the reaction was completed, vacuum distillation was carried out to obtain an intermediate product; 17 parts by weight of 3,4-dimethylphenylboronic acid and 12 parts by weight of diethylenetriamine were dispersed in 500 parts by weight of deionized water, and the pH was adjusted to 11, then 3.2 parts by weight of formaldehyde was added, and stirring was carried out at 55°C for 5 hours, after the reaction was completed, isopropyl alcohol was used for precipitation, centrifugation was carried out at a speed of 9000 r / min for 10 minutes, and vacuum drying was carried out to obtain aminoboronic acid; 40 parts by weight of aminoboronic acid, 55 parts by weight of triethylamine and 0.26 parts by weight of copper chloride were dispersed in 200 parts by weight of N,N-dimethylformamide, 30 parts by weight of the intermediate product was slowly added dropwise, stirring was carried out at 5°C for 7 hours, then the temperature was raised to 25°C and stirring was continued for 20 hours, after the reaction was completed, filtration, washing and vacuum drying were carried out in sequence to obtain a boronic acid-based phosphorus-nitrogen flame retardant.

[0072] Preparation Example 14:

[0073] The preparation method of the boronic acid-based phosphorus-nitrogen flame retardant comprises the following steps:

[0074] 18 parts by weight of phosphorus oxychloride was dispersed in 11 parts by weight of anhydrous ethanol, after stirring at 5°C for 5h, the temperature was raised to 25°C and stirred for 8h, after the reaction was completed, vacuum distillation to obtain the intermediate product; 40 parts by weight of diethylenetriamine, 55 parts by weight of triethylamine and 0.26 parts by weight of copper chloride were dispersed in 200 parts by weight of N,N-dimethylformamide, slowly drop 30 parts by weight of the intermediate product, after stirring at 5°C for 7h, the temperature was raised to 25°C and stirred for 20h, after the reaction was completed, filtration, washing and vacuum drying in sequence to obtain the borate-based phosphorus-nitrogen flame retardant.

[0075] Preparation Example 15:

[0076] The preparation method of the borate-based phosphorus-nitrogen flame retardant comprises the following steps:

[0077] 18 parts by weight of phosphorus oxychloride was dispersed in 20 parts by weight of anhydrous ethanol, after stirring at 5°C for 5h, the temperature was raised to 25°C and stirred for 8h, after the reaction was completed, vacuum distillation to obtain the intermediate product; 17 parts by weight of 3,4-dimethylphenylboronic acid and 12 parts by weight of diethylenetriamine were dispersed in 500 parts by weight of deionized water, and the pH was adjusted to 11, then 3.2 parts by weight of formaldehyde was added, and stirred at 55°C for 5h, after the reaction was completed, isopropyl alcohol was used for precipitation, centrifuged at 9000r / min for 10min, and then vacuum dried to obtain aminated phenylboronic acid; 40 parts by weight of aminated phenylboronic acid, 55 parts by weight of triethylamine and 0.26 parts by weight of copper chloride were dispersed in 200 parts by weight of N,N-dimethylformamide, slowly drop 30 parts by weight of the intermediate product, after stirring at 5°C for 7h, the temperature was raised to 25°C and stirred for 20h, after the reaction was completed, filtration, washing and vacuum drying in sequence to obtain the borate-based phosphorus-nitrogen flame retardant.

[0078] Example 1:

[0079] The preparation method of a high flame-retardant and anti-dripping fiber comprises the following steps:

[0080] 35 parts by weight of the modified polylactic acid prepared in Preparation Example 1, 4 parts by weight of the borate-based phosphorus-nitrogen flame retardant prepared in Preparation Example 9 and 0.062 parts by weight of p-toluenesulfonic acid were dispersed in 200 parts by weight of mixed solvent (V 二氯甲烷 :V 二 toluene = 3:2), stirred at 145°C for 2h, and the reaction was completed to obtain a composite; 10 parts by weight of acrylonitrile, 0.1 parts by weight of eugenol, 0.5 parts by weight of glycidyl methacrylate, 7 parts by weight of 50% sodium thiocyanate solution and 0.065 parts by weight of azobisisobutyronitrile were dispersed in 50 parts by weight of mixed solvent (V 二甲基亚砜 :V 去离子水= 3:1) under nitrogen protection at 65°C for 5h, and then the modified polyacrylonitrile was obtained by filtration, washing and vacuum drying in sequence; 20 parts by weight of the modified polyacrylonitrile and 50 parts by weight of the composite were melt blended at 200°C for 10min to obtain a composite material, and the composite material was melt spun at a spinning temperature of 195°C, a side air blowing temperature of 24°C and a cold zone air speed of 0.4m / s to obtain the high flame-retardant melt-drip-resistant fiber.

[0081] Example 2

[0082] A method for preparing a high flame-retardant melt-drip-resistant fiber, comprising the following steps:

[0083] 36 parts by weight of the modified polylactic acid prepared in Preparation Example 2, 4.5 parts by weight of the boric acid-based phosphorus-nitrogen flame retardant prepared in Preparation Example 10 and 0.064 parts by weight of p-toluenesulfonic acid were dispersed in 200 parts by weight of a mixed solvent (V 二氯甲烷 :Vxylene = 3:2) under stirring at 147°C for 2.2h, and then the composite was obtained; 11 parts by weight of acrylonitrile, 0.12 parts by weight of eugenol, 0.6 parts by weight of glycidyl methacrylate, 7.2 parts by weight of a sodium thiocyanate solution with a concentration of 50% and 0.067 parts by weight of azobisisobutyronitrile were dispersed in 50 parts by weight of a mixed solvent (V 二甲基亚砜 :V 去离子水 = 3:1) under nitrogen protection at 67°C for 5.2h, and then the modified polyacrylonitrile was obtained by filtration, washing and vacuum drying in sequence; 22 parts by weight of the modified polyacrylonitrile and 53 parts by weight of the composite were melt blended at 205°C for 12min to obtain a composite material, and the composite material was melt spun at a spinning temperature of 200°C, a side air blowing temperature of 25°C and a cold zone air speed of 0.5m / s to obtain the high flame-retardant melt-drip-resistant fiber.

[0084] Example 3

[0085] A method for preparing a high flame-retardant melt-drip-resistant fiber, comprising the following steps:

[0086] 37 parts by weight of the modified polylactic acid prepared in Preparation Example 3, 5 parts by weight of the boric acid-based phosphorus-nitrogen flame retardant prepared in Preparation Example 11 and 0.067 parts by weight of p-toluenesulfonic acid were dispersed in 200 parts by weight of a mixed solvent (V 二氯甲烷 :V 二 toluene = 3:2) under stirring at 148°C for 2.5h, and then the composite was obtained; 13 parts by weight of acrylonitrile, 0.15 parts by weight of eugenol, 0.7 parts by weight of glycidyl methacrylate, 7.5 parts by weight of a sodium thiocyanate solution with a concentration of 50% and 0.071 parts by weight of azobisisobutyronitrile were dispersed in 50 parts by weight of a mixed solvent (V 二甲基亚砜 :V 去离子水In a nitrogen-protected environment, the mixture was stirred at 70°C for 5.5 h in a ratio of 3:1. After the reaction, the mixture was filtered, washed and vacuum dried to obtain modified polyacrylonitrile. 23 parts by weight of modified polyacrylonitrile and 56 parts by weight of the composite were melt-blended at 210°C for 15 min to obtain a composite material. The composite material was melt-spun in a melt spinning machine at a spinning temperature of 205°C, a side blowing temperature of 26°C and a cold zone wind speed of 0.4 m / s to obtain high flame retardant and anti-dripping fiber.

[0087] Example 4:

[0088] A method for preparing a highly flame-retardant and anti-dripping fiber includes the following steps:

[0089] 38 parts by weight of the modified polylactic acid prepared in Preparation Example 4, 5.5 parts by weight of the borate-based phosphorus-nitrogen flame retardant prepared in Preparation Example 12, and 0.073 parts by weight of p-toluenesulfonic acid were dispersed in 200 parts by weight of a mixed solvent (V 二氯甲烷 In a mixture of xylene and acrylonitrile (V:V xylene = 3:2), the mixture was stirred at 152°C for 2.8 h. After the reaction was completed, a complex was obtained. 14 parts by weight of acrylonitrile, 0.18 parts by weight of eugenol, 0.7 parts by weight of glycidyl methacrylate, 7.7 parts by weight of a 50% sodium thiocyanate solution, and 0.073 parts by weight of azobisisobutyronitrile were dispersed in 50 parts by weight of a mixed solvent (V:V xylene = 3:2). 二甲基亚砜 V 去离子水 In a nitrogen-protected environment, the mixture was stirred at 72°C for 5.8 h in a ratio of 3:1. After the reaction, the mixture was filtered, washed and vacuum dried to obtain modified polyacrylonitrile. 24 parts by weight of modified polyacrylonitrile and 60 parts by weight of the composite were melt-blended at 215°C for 18 min to obtain a composite material. The composite material was melt-spun in a melt spinning machine at a spinning temperature of 210°C, a side blowing temperature of 25°C and a cold zone wind speed of 0.6 m / s to obtain high flame retardant and anti-dripping fiber.

[0090] Example 5:

[0091] A method for preparing a highly flame-retardant and anti-dripping fiber includes the following steps:

[0092] 40 parts by weight of the modified polylactic acid prepared in Preparation Example 5, 6 parts by weight of the borate-based phosphorus-nitrogen flame retardant prepared in Preparation Example 13, and 0.075 parts by weight of p-toluenesulfonic acid were dispersed in 200 parts by weight of a mixed solvent (V 二氯甲烷 V 二甲苯 In a mixture of 3:2 (ratio), the mixture was stirred at 155°C for 3 hours, and the reaction was completed to obtain a complex. 15 parts by weight of acrylonitrile, 0.2 parts by weight of eugenol, 0.8 parts by weight of glycidyl methacrylate, 8 parts by weight of a 50% sodium thiocyanate solution, and 0.075 parts by weight of azobisisobutyronitrile were dispersed in 50 parts by weight of a mixed solvent (V...). 二甲基亚砜 V 去离子水= 3:1) was stirred at 75℃ for 6h under nitrogen protection, and then the modified polyacrylonitrile was obtained by filtration, washing and vacuum drying in sequence. 25 parts by weight of the modified polyacrylonitrile and 65 parts by weight of the composite were melt blended at 220℃ for 20min to obtain a composite material, and the high flame-retardant melt-drip-resistant fiber was prepared by melt spinning at a spinning temperature of 220℃, a side blowing temperature of 27℃ and a cold zone wind speed of 0.6m / s.

[0093] Comparative Example 1:

[0094] A method for preparing a high flame-retardant melt-drip-resistant fiber, comprising the following steps:

[0095] The modified polylactic acid prepared in Preparation Example 5 in Example 5 was replaced by the modified polylactic acid prepared in Preparation Example 6, and the other operations remained the same as in Example 5.

[0096] Comparative Example 2:

[0097] A method for preparing a high flame-retardant melt-drip-resistant fiber, comprising the following steps:

[0098] The modified polylactic acid prepared in Preparation Example 5 in Example 5 was replaced by the modified polylactic acid prepared in Preparation Example 7, and the other operations remained the same as in Example 5.

[0099] Comparative Example 3:

[0100] A method for preparing a high flame-retardant melt-drip-resistant fiber, comprising the following steps:

[0101] The modified polylactic acid prepared in Preparation Example 5 in Example 5 was replaced by the polylactic acid prepared in Preparation Example 8, and the other operations remained the same as in Example 5.

[0102] Comparative Example 4:

[0103] A method for preparing a high flame-retardant melt-drip-resistant fiber, comprising the following steps:

[0104] The borate-based phosphorus-nitrogen flame retardant prepared in Preparation Example 13 in Example 5 was replaced by the borate-based phosphorus-nitrogen flame retardant prepared in Preparation Example 14, and the other operations remained the same as in Example 5.

[0105] Comparative Example 5:

[0106] A method for preparing a high flame-retardant melt-drip-resistant fiber, comprising the following steps:

[0107] The borate-based phosphorus-nitrogen flame retardant prepared in Preparation Example 13 in Example 5 was replaced by the borate-based phosphorus-nitrogen flame retardant prepared in Preparation Example 15, and the other operations remained the same as in Example 5.

[0108] Comparative Example 6:

[0109] A preparation method of high flame-retardant anti-dripping fiber, comprising the following steps:

[0110] In Example 5, 25 parts by weight of modified polyacrylonitrile was replaced by 50 parts by weight of modified polyacrylonitrile, and other operations were consistent with Example 5.

[0111] Comparative Example 7:

[0112] A preparation method of high flame-retardant anti-dripping fiber, comprising the following steps:

[0113] 40 parts by weight of modified polylactic acid prepared in Preparation Example 5, 6 parts by weight of boric acid-based phosphorus-nitrogen flame retardant prepared in Preparation Example 13 and 0.075 parts by weight of p-toluenesulfonic acid were dispersed in 200 parts by weight of mixed solvent (V 二氯甲烷 :V 二 toluene = 3:2) and stirred at 155℃ for 3h, and a composite was obtained after the reaction was completed; the composite was melt-spun to obtain high flame-retardant anti-dripping fiber in a melt spinning machine at a spinning temperature of 220℃, a side blowing temperature of 27℃ and a cold zone wind speed of 0.6m / s.

[0114] Performance detection:

[0115] Test Example 1: Flame-retardant performance test:

[0116] Vertical burning test (UL-94): according to GB / T 2408-2008 standard, the high flame-retardant anti-dripping fiber prepared in Examples 1-5 and Comparative Examples 1-7 was made into a sample of 125mm×12mm×3mm, and a vertical burning test was performed;

[0117] Limiting oxygen index test (LOI): according to GB / T 2406.2-2009 standard, the high flame-retardant anti-dripping fiber prepared in Examples 1-5 and Comparative Examples 1-7 was made into a sample of 125mm×6mm×3mm, and a limiting oxygen index test was performed; the detection results are shown in Table 1.

[0118] Table 1. Flame-retardant performance test

[0119]

[0120] It can be observed from the test data in Table 1 that the high flame-retardant anti-dripping fibers prepared in Examples 1-5 have good flame-retardant and anti-dripping properties. The comparative examples 1-3 may be that the content of hydroxyl groups in the modified polylactic acid is lower than that in the modified polylactic acid in Examples 1-5, which cannot form a crosslinked network, resulting in a decrease in flame-retardant and anti-dripping properties. The comparative example 4 may be that the lack of phenylboronic acid cannot form a better synergistic effect with phosphorus and nitrogen, affecting its flame-retardant and anti-dripping properties. The comparative example 5 may be that the high content of anhydrous ethanol leads to a decrease in the content of chlorine atoms in the intermediate product, which cannot fully react with the aminoboronic acid, affecting the dispersibility of phosphorus and nitrogen in the modified polylactic acid, and thus leading to a decrease in flame-retardant properties.

[0121] Test Example 2: Water washing resistance:

[0122] According to the test in GB / T 3921.1-1997, the flame-retardant properties of the high flame-retardant anti-dripping fibers prepared in Examples 1-5 and Comparative Examples 1-7 after 30 times of water washing were detected, and the test results are shown in Table 2.

[0123] Table 2. Water washing resistance test

[0124]

[0125] It can be observed from the test results in Table 2 that the high flame-retardant anti-dripping fibers prepared in Examples 1-5 have good water washing resistance and still have good flame-retardant and anti-dripping properties after 30 times of water washing. The decrease in properties of the high flame-retardant anti-dripping fibers prepared in Comparative Example 5 after 30 times of water washing may be due to the decrease in the content of phosphorus and nitrogen in the flame retardant after several times of water washing, affecting its flame-retardant and anti-dripping properties.

[0126] Test Example 3: Mechanical property test:

[0127] The tensile strength of the high flame-retardant anti-dripping fibers prepared in Examples 1-5 and Comparative Examples 1-7 was tested according to GB / T 1040.2-2006 standard, and the test results are shown in Table 3.

[0128] Table 3. Mechanical property test

[0129] Tensile strength (MPa) Example 1 82.1 Example 2 83.9 Example 3 84.2 Example 4 85.8 Example 5 87.3 Comparative Example 1 67.1 Comparative Example 2 65.1 Comparative Example 3 62.2 Comparative Example 4 61.3 Comparative Example 5 63.9 Comparative Example 6 58.1 Comparative Example 7 45.7

[0130] It can be observed from the test results in Table 3 that the high flame-retardant melt-drip-resistant fibers prepared in Examples 1-5 of the present application have good mechanical properties. It can be observed from Comparative Example 7 that the introduction of modified polyacrylonitrile can improve the brittleness defect of modified polylactic acid used alone and improve the tensile strength. The decrease in the mechanical properties of the high flame-retardant melt-drip-resistant fibers prepared in Comparative Example 6 is probably due to the fact that the content of modified polyacrylonitrile is too high, which affects the interfacial bonding force between the modified polylactic acid and the modified polyacrylonitrile, thereby reducing the tensile strength.

[0131] The above-described embodiments illustrate the technical solutions and beneficial effects of the present application in detail. It should be understood that the above-described embodiments are only specific embodiments of the present application and are not intended to limit the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A method for preparing a highly flame-retardant and anti-dripping fiber, characterized in that, The preparation method includes the following steps: Modified polylactic acid, borate-based phosphorus-nitrogen flame retardant, and a first catalyst were reacted in a weight ratio of 35–40:4–6:0.062–0.075 to obtain a composite. Acrylonitrile, eugenol, glycidyl methacrylate, sodium thiocyanate, and azobisisobutyronitrile were reacted in a weight ratio of 10–15:0.1–0.2:0.5–0.8:7–8:0.065–0.075 to obtain modified polyacrylonitrile. The modified polyacrylonitrile and the composite were melt-blended and melt-spun sequentially in a weight ratio of 20–25:50–65 to obtain the highly flame-retardant and anti-dripping fiber.

2. The method for preparing a high flame-retardant and anti-dripping fiber as described in claim 1, characterized in that, The preparation method of the modified polylactic acid includes the following steps: After 30-40 parts by weight of lactic acid undergoes a prepolymerization reaction to obtain a prepolymer, 2-3 parts by weight of succinic anhydride and 0.3-0.4 parts by weight of a second catalyst are added to react and obtain carboxyl-terminated polylactic acid. Modified polylactic acid is obtained by reacting 20-30 parts by weight of carboxyl-terminated polylactic acid, 0.5-1.2 parts by weight of sorbitol and 0.25-0.38 parts by weight of a third catalyst.

3. The method for preparing a high flame-retardant and anti-dripping fiber as described in claim 2, characterized in that, The reaction conditions for lactic acid, succinic anhydride, and the second catalyst include a reaction temperature of 145–155 °C and a reaction time of 6–8 h.

4. The method for preparing a high flame-retardant and anti-dripping fiber as described in claim 2, characterized in that, The reaction conditions for the terminal carboxyl polylactic acid, sorbitol and the third catalyst include a reaction temperature of 55-65°C and a reaction time of 8-10 h.

5. The method for preparing a high flame-retardant and anti-dripping fiber as described in claim 1, characterized in that, The preparation method of the borate-based phosphorus nitrogen flame retardant includes the following steps: Phosphorus oxychloride and anhydrous ethanol react in a weight ratio of 15–18:9–11 to obtain an intermediate product. 3,4-Dimethylphenylboronic acid, diethylenetriamine, and formaldehyde react in a weight ratio of 15–17:10–12:2.8–3.2 to obtain aminophenylboronic acid. Aminophenylboronic acid, the intermediate product, triethylamine, and a fourth catalyst react in a weight ratio of 35–40:26–30:40–55:0.23–0.26 to prepare the borate-based phosphorus-nitrogen flame retardant.

6. The method for preparing a high flame-retardant and anti-dripping fiber as described in claim 5, characterized in that, The reaction conditions for phosphorus oxychloride and anhydrous ethanol are as follows: react at 0-5°C for 4-5 hours, then raise the temperature to 23-25°C and react for 6-8 hours.

7. The method for preparing a high flame-retardant and anti-dripping fiber as described in claim 5, characterized in that, The reaction conditions for the amino-modified phenylboronic acid, intermediate product, triethylamine and fourth catalyst are: reaction at 0-5°C for 6-7 h, followed by reaction at 23-25°C for 18-20 h.

8. The method for preparing a high flame-retardant and anti-dripping fiber as described in claim 1, characterized in that, The reaction conditions for the modified polylactic acid, borate-based phosphorus nitrogen flame retardant and the first catalyst include a reaction temperature of 145-155°C and a reaction time of 2-3 hours.

9. The method for preparing a high flame-retardant and anti-dripping fiber as described in claim 1, characterized in that, The reaction conditions for acrylonitrile, eugenol, glycidyl methacrylate, sodium thiocyanate, and azobisisobutyronitrile include a reaction temperature of 65–75 °C and a reaction time of 5–6 h.

10. A highly flame-retardant and anti-dripping fiber, characterized in that, The high flame-retardant and anti-dripping fiber is prepared by any one of the preparation methods described in claims 1 to 9.

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