Heat-insulating flame-retardant yarn and preparation method thereof

Abstract

The invention relates to the field of yarns, in particular to a heat-insulating and flame-retardant yarn and a preparation method thereof, which are used for solving the problems that the traditional yarn has poor heat-insulating and flame-retardant performance effects and is difficult to meet the requirements that the yarn is not heat-insulating and inflammable at a high temperature or at a place with open fire. The yarn takes nylon 66 particles as a base material, the nylon 66 particles have good heat resistance, wear resistance and higher fatigue strength and rigidity, and a modified flame retardant and modified viscose fibers are added into the nylon 66 particles, so that P-N bonds with strong catalytic action are formed in the combustion process, dehydration is promoted, and the flame retardance is improved. The flame retardant is heated to decompose to generate non-combustible gases, the non-combustible gases jointly act to form an expanded carbon layer with a better isolation effect, the flame retardant efficiency can be effectively improved, the outer layer is covered with the modified composite heat insulation coating, and the coating contains an Si O2 nano porous material which is formed by connecting a plurality of S -O-S groups and is used for reducing the heat conductivity coefficient and improving the heat insulation performance.

Description

Technical Field

[0001] This invention relates to the field of yarn, and more specifically to a heat-insulating and flame-retardant yarn and its preparation method. Background Technology

[0002] With the improvement of people's living standards and the enhancement of safety awareness, the demand for yarns with both heat insulation and flame retardant properties has surged in fields such as industrial protection, home decoration, and vehicle interiors. For example, firefighter suits need to withstand high-temperature flames, and automotive interiors need to reduce the risk of combustion, making the heat insulation and flame retardant properties of textiles particularly important. Fires caused by flammable textiles are one of the main causes of casualties and property losses worldwide. Traditional flame retardants mainly achieve fire prevention through catalytic charring or gas-phase free radical quenching, but their heat insulation performance is insufficient at high temperatures and cannot effectively block heat radiation conduction. Firefighter suits, military training uniforms, etc., need to meet both flame retardant and heat insulation requirements.

[0003] Therefore, developing a heat-insulating and flame-retardant yarn with high heat insulation performance, difficulty in being ignited, or self-extinguishing properties is of great practical significance. Summary of the Invention

[0004] In order to overcome the above-mentioned technical problems, the present invention aims to provide a heat-insulating and flame-retardant yarn and its preparation method, which solves the problems of poor heat insulation performance and flammability of existing yarns, and provides a heat-insulating and flame-retardant yarn that simultaneously has heat insulation, flame retardancy, is more difficult to ignite or self-spread in a fire, has strong flame retardant performance, and has self-extinguishing properties, that is, it can extinguish itself after leaving the fire source.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] In a first aspect, a method for preparing a heat-insulating and flame-retardant yarn includes the following steps:

[0007] Step 1: Weigh out the following components by weight: 40-60 parts nylon 66 granules, 5-15 parts modified flame retardant, 5-15 parts modified composite heat insulation coating, 20-35 parts modified viscose fiber, 10-20 parts glass fiber, 0.5-2 parts coupling agent, 0.2-0.5 parts antioxidant, and 1-3 parts nano-grade titanium dioxide. Set aside.

[0008] Step 2: Nylon 66 particles, nano-sized titanium dioxide, modified flame retardant, antioxidant, and coupling agent are added to a high-speed mixer at 1500-3000 r / min and mixed evenly. Then, the mixture is added to a twin-screw extruder at 240-260℃ for melt extrusion. The mixture is then added to an electrostatic spinning machine for spinning into yarn. After being mixed evenly with modified viscose fiber and glass fiber, the yarn is added to a vortex spinning machine for spinning to obtain yarn.

[0009] Step 3: Immerse the yarn in γ-aminopropyltriethoxysilane solution for 20-30 minutes, wash with water, and dry at 80°C. Then immerse it in phytic acid solution for 10-20 minutes, wash with water, and dry at 80°C. Repeat this process 5-10 times. Then, immerse the formed yarn in an impregnation tank containing modified composite heat-insulating coating for 20-30 minutes. Finally, send the yarn into an oven at 90-130°C for drying and curing to obtain heat-insulating and flame-retardant yarn.

[0010] As a further aspect of the present invention: the coupling agent in step one is coupling agent KH550; the antioxidant is antioxidant 1010.

[0011] As a further aspect of the present invention: the bath ratio of the yarn to the γ-aminopropyltriethoxysilane solution, phytic acid solution and modified composite heat insulation coating in step three is 1:10:10-15:10; the mass fraction of the γ-aminopropyltriethoxysilane solution is 5%, and the mass fraction of the phytic acid solution is 2%.

[0012] The modified flame retardant is prepared by the following steps:

[0013] Step a1: Add citric acid and dichloromethane to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel, stir at 350-450 r / min, add sodium hypophosphite, transfer to constant pressure dropping funnel, cool to 0-5℃ and maintain low temperature stirring for 1 h, heat to 80-85℃, stir at 350-450 r / min for 5-7 h, extract, wash and dry, remove solvent by vacuum distillation to obtain intermediate 1;

[0014]

[0015] Step a2: Add intermediate 1, guar gum and deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 30-50 min at a temperature of 50-60℃ and a stirring rate of 350-450 r / min. Add sodium hypophosphite and transfer to a constant pressure dropping funnel. Stir for 1-3 h. Raise the temperature to 80-85℃ and stir at 500 r / min for 6 h. After the reaction is complete, cool the reaction product to room temperature, allow it to stand to precipitate, and dry it to obtain intermediate 2.

[0016]

[0017] Step a3: Diethyl chlorophosphate and tetrahydrofuran were added to a three-necked flask, nitrogen gas was introduced for protection, and the temperature was maintained at 0-5℃. Methacrylamide was dissolved in tetrahydrofuran and added dropwise to the three-necked flask. Then triethylamine was added to the three-necked flask, the temperature was raised to 35-40℃, and the reaction was carried out for 10-12 hours. The solvent was removed by rotary evaporation to obtain intermediate 3.

[0018]

[0019] Step a4: Add intermediate 3 and deionized water to a three-necked flask, and adjust the pH of the mixture to 3.5 using a 20% sodium hydroxide aqueous solution. Heat to 70°C and stir for 10 min. Add potassium persulfate to the flask and stir for 15 min. Add intermediate 2 to the flask and continue stirring for 30 min. Rinse with deionized water and dry to obtain intermediate 4.

[0020]

[0021] Step a5: Add intermediate 2 and ammonium polyphosphate to a three-necked flask equipped with a stirrer, thermometer and reflux condenser. Stir for 1-1.5 h at a temperature of 25-30℃ and a stirring rate of 200 r / min. Then, while stirring, raise the temperature to reflux, add deionized water and continue stirring for 5 h. After the reaction is completed, neutralize with sodium bicarbonate at 40℃ for 10 min, rinse with deionized water 3-4 times, and dry at 80℃ to obtain the modified flame retardant.

[0022]

[0023] As a further aspect of the present invention: the ratio of citric acid, dichloromethane and sodium hypophosphite used in step a1 is 15-25g: 80-100mL: 1-5g.

[0024] As a further aspect of the present invention: the ratio of intermediate 1, guar gum, deionized water and sodium hypophosphite in step a2 is 20-25g: 3-5g: 200mL: 1-5g.

[0025] As a further aspect of the present invention: the ratio of diethyl chlorophosphate, tetrahydrofuran, methacrylamide and triethylamine used in step a3 is 9-9.5g:100mL:8.5-9g:5-5.5g.

[0026] As a further aspect of the present invention: the ratio of intermediate 3, deionized water, potassium persulfate and intermediate 2 in step a4 is 7-8g: 20-25mL: 0.8-1g: 10-15g.

[0027] As a further aspect of the present invention: the ratio of intermediate 2 and ammonium polyphosphate in step a5 is 20-25g: 25-30g; the ammonium polyphosphate is ammonium polyphosphate CF-IFR.

[0028] As a further aspect of the present invention: the modified composite heat-insulating coating is prepared by the following steps:

[0029] Step b1: Add agarose, polyvinyl alcohol, and deionized water to a glass container. Heat and stir in a magnetically stirred water bath at 85°C and 300 rpm for 10-30 min. Add the aerogel to ethanol and mix. Add the mixture to the above polymer aqueous solution. Heat and stir in a magnetically stirred water bath at 85°C and 500-1000 rpm for 1-2 h. Then add it dropwise to 201 methyl silicone oil and stir at 1000 rpm for 30-40 min. Centrifuge and wash 4-5 times with ethanol and water to obtain the modified aerogel for later use.

[0030] Step b2: Add the wetting agent, dispersant, compatibilizer, defoamer, bactericide, and thickener to deionized water in sequence, and stir at 500-1000 r / min for 20-30 min. Then add TiO2, hollow glass microspheres, and modified aerogel in sequence, and stir at 2500-3000 r / min for 30-40 min. Add the film-forming aid and pure acrylic emulsion to the solution, and stir at 2500 r / min for 60-80 min to obtain the modified composite heat insulation coating.

[0031] As a further aspect of the present invention: the ratio of agarose, polyvinyl alcohol, deionized water, aerogel and ethanol in step b1 is 0.15-1g: 0.1-0.9g: 100mL: 3g: 50mL; the agarose is LP0028A agarose; the polyvinyl alcohol is polyvinyl alcohol PVA2488; and the aerogel is LBF-aerogel.

[0032] As a further aspect of the present invention: the ratio of wetting agent, dispersant, compatibilizer, defoamer, bactericide, thickener and deionizer in step b2 is 5-10mL: 5-10mL: 15mL: 5mL: 10mL: 15mL: 100mL; the ratio of TiO2, hollow glass microspheres, modified aerogel, film-forming aid and pure acrylic emulsion is 10g: 5-25g: 5-30g: 10mL: 15mL.

[0033] As a further aspect of the present invention: the wetting agent, dispersant, compatibilizer, defoamer, bactericide and thickener in step b2 are respectively wetting agent ND1096, dispersant BYK-U80, compatibilizer POE, defoamer PX-122, bactericide LXE and thickener AT50.

[0034] As a further embodiment of the present invention: the TiO2, hollow glass microspheres, film-forming aid and pure acrylic emulsion in step b2 are respectively rutile TiO2 PTT-P20, hollow glass microspheres K46, film-forming aid TEXANOL and pure acrylic emulsion BA-201.

[0035] As a further aspect of the present invention: the modified viscose fiber is prepared by the following steps:

[0036] Step C1: Place urea in a muffle furnace and heat at 550°C for 4-6 hours at a heating rate of 2°C / min to obtain carbon nitride. After cooling at room temperature, grind it into powder using an agate mortar. Add red phosphorus to deionized water and hydrothermally treat it in a reaction vessel at 200°C for 12-14 hours to obtain amorphous phosphorus powder for later use.

[0037] Step C2: Add carbon nitride and amorphous phosphorus powder to slurry and grind them. Transfer the resulting powder to a quartz ampoule and seal it with an oxyhydrogen flame under a low vacuum of 100-1000 Pa. Heat the ampoule in a furnace at 400-550℃ at a heating rate of 2℃ / min for 4 hours. After slowly cooling to room temperature, break the capsule and wash it with CS2, ethanol and distilled water respectively to obtain red phosphorus carbon nitride.

[0038] Step C3: Add red phosphorus carbon nitride to the viscose solution and stir for 2-3 hours. Place it in a vacuum oven and degas at -25 kPa for 4-5 hours. Then add it to the spinning equipment and press it into the coagulation bath under a pressure of 2 MPa. Spin it out through a 300-hole spinneret and enter the coagulation bath, then the weak acid bath, then the stretching bath, and then the alkali washing in 200 mL of 1% sodium hydroxide solution. Finally, wash it with deionized water and dry the spun fiber under vacuum at 50°C to obtain modified viscose fiber.

[0039] As a further aspect of the present invention: the ratio of urea, red phosphorus and deionized water used in step c1 is 10-15g: 1-2g: 60-80mL.

[0040] As a further aspect of the present invention: the ratio of carbon nitride to amorphous phosphorus powder in step c2 is 500mg:200mg.

[0041] As a further aspect of the present invention: the ratio of red phosphorus carbon nitride to viscose solution in step c3 is 2-4g:495-500g; the viscose solution is a pure viscose spinning solution with a cellulose content of 8.9%; the coagulation bath is a mixed solution of 12g / L ZnSO4, 270g / L Na2SO4, and 130g / L H2SO4; the weak acid bath is a mixed solution of 4g / L ZnSO4, 90g / L Na2SO4, and 43g / L H2SO4; and the stretching bath is deionized water.

[0042] Secondly, the present invention provides a heat-insulating and flame-retardant yarn, which is prepared by the above method.

[0043] The beneficial effects of this invention are:

[0044] The present invention discloses a method for preparing heat-insulating and flame-retardant yarn, which involves uniformly mixing nylon 66 particles, nano-sized titanium dioxide, modified flame retardant, and antioxidant in a high-speed mixer, melt-extruding the mixture in a twin-screw extruder, then uniformly mixing it together with modified viscose fiber and glass fiber in an opening and blending device, and finally feeding it into a vortex spinning machine to obtain yarn. The yarn is then impregnated in a γ-aminopropyltriethoxysilane solution, washed with water, and dried; subsequently impregnated in a phytic acid solution, washed with water, and dried, repeated 5-10 times. The yarn is impregnated in an impregnation tank containing a modified composite heat-insulating coating, and then dried and cured in an oven to obtain a heat-insulating and flame-retardant yarn. This preparation method uses nylon 66 particles as the main raw material. Nylon 66 particles have good heat resistance, wear resistance, and high fatigue strength and rigidity. By adding modified flame retardants and modified viscose fibers, the heat resistance and flame retardant properties of the yarn can be significantly improved. Adding a modified composite heat-insulating coating to the outer layer of the yarn can reduce the thermal conductivity and improve the heat insulation performance.

[0045] In the preparation of heat-insulating and flame-retardant yarn, a modified flame retardant was first prepared. First, citric acid and dichloromethane were stirred, and sodium hypophosphite was added, resulting in intramolecular dehydration to form a carbonate group, yielding intermediate 1. Intermediate 1 was then stirred with guar gum, and sodium hypophosphite was added, resulting in esterification that introduced a guar gum structure onto intermediate 1, yielding intermediate 2. Diethyl chlorophosphate was dissolved in tetrahydrofuran, and methacrylamide was dissolved in tetrahydrofuran. After mixing, triethylamine was added, resulting in an addition reaction that introduced a PN bond onto diethyl chlorophosphate, yielding intermediate 3. Intermediate 3, potassium persulfate, and intermediate 2 were mixed and stirred, resulting in an addition reaction that introduced the PN bond from intermediate 3 into the guar gum structure of intermediate 2, yielding intermediate 4. Intermediate 4 was then stirred with ammonium polyphosphate, introducing a large amount of P and NH4+ onto the carboxyl group. + A modified flame retardant was obtained; this flame retardant has a phosphorus-nitrogen flame retardant system that not only has the flame retardant mechanism of both phosphorus and nitrogen elements, but also can form PN bonds with stronger catalytic effect during combustion, which promotes dehydration. The flame retardant decomposes upon heating to produce non-flammable gases, which together form an expanded char layer with better insulation effect, which can effectively improve the flame retardant efficiency.

[0046] In the preparation of heat-insulating and flame-retardant yarn, a modified composite heat-insulating coating was first prepared. Agarose, polyvinyl alcohol, and deionized water were added to a glass container and stirred in a magnetically stirred water bath. Aerogel was added to ethanol and stirred, then added to the above polymer aqueous solution and stirred. It was then added dropwise to 201 methyl silicone oil and stirred. After centrifugation, it was washed with ethanol and water to obtain modified aerogel. Then, wetting agent, dispersant, compatibilizer, defoamer, bactericide, and thickener were added to deionized water in sequence and stirred. TiO2, hollow glass microspheres, and modified aerogel were added in sequence and stirred. Film-forming aid and pure acrylic emulsion were added to the solution and stirred at high speed. Then, it was coated on an aluminum sheet and dried at room temperature to obtain the modified composite heat-insulating coating. The coating contains SiO2 nanoporous material, which has ultra-low density, low thermal conductivity, and extremely high porosity. The three-dimensional network structure is composed of many Si-O-Si groups connected to each other. It is added as a functional filler to the heat-insulating coating to reduce the thermal conductivity of the coating and improve the heat insulation performance of the coating.

[0047] In the process of preparing heat-insulating and flame-retardant yarn, a modified viscose fiber was first prepared. Urea was placed in a muffle furnace and heated to form carbon nitride. After cooling at room temperature, it was ground into powder using an agate mortar. Red phosphorus was added to deionized water and hydrothermally treated to obtain amorphous phosphorus powder. Carbon nitride and amorphous phosphorus powder were added to slurry and ground. The resulting powder was transferred to a quartz ampoule, heated, and slowly cooled to room temperature. The ampoule was then broken up and washed with CS2, ethanol, and distilled water. P was introduced into the carbon nitride to obtain red phosphorus carbon nitride. Red phosphorus carbon nitride is added to the viscose solution and stirred. The solution is then placed in a vacuum oven for degassing, and then added to a spinning device. It is extruded into a coagulation bath and spun out through a 300-hole spinneret. After entering the coagulation bath, it enters a weak acid bath, then a stretching bath, and then an alkaline wash in a sodium hydroxide solution. Finally, it is washed with deionized water and dried to obtain modified viscose fiber. The modified viscose fiber mainly achieves a flame-retardant effect by forming a dense carbon layer on the fiber surface through the synergistic effect of phosphorus and nitrogen elements, which prevents the transfer of heat and oxygen. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] Example 1:

[0050] This embodiment describes a method for preparing heat-insulating and flame-retardant yarn, including the following steps:

[0051] Step s1: Add 15g of citric acid and 80mL of dichloromethane to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. Stir at 350r / min, add 1g of sodium hypophosphite, transfer to constant pressure dropping funnel, cool to 0℃ and maintain low temperature stirring for 1h, heat to 80℃ and stir at 350r / min for 5h, extract, wash and dry, remove solvent by vacuum distillation to obtain intermediate 1;

[0052] Step s2: Add 20g of intermediate 1, 3g of guar gum and 200mL of deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 30min at 50℃ and 350r / min. Add 1g of sodium hypophosphite and transfer to a constant pressure dropping funnel. Stir for 1h. Raise the temperature to 80℃ and stir at 500r / min for 6h. After the reaction is complete, cool the reaction product to room temperature, let it stand to precipitate, and dry to obtain intermediate 2.

[0053] Step s3: Add 9g of diethyl chlorophosphate and 50mL of tetrahydrofuran to a three-necked flask, purge with nitrogen and keep the temperature at 0℃. Dissolve 8.5g of methacrylamide in 50mL of tetrahydrofuran and add it dropwise to the three-necked flask. Then add 5g of triethylamine to the three-necked flask, heat to 35℃, and react for 10h. Remove the solvent by rotary evaporation to obtain intermediate 3.

[0054] Step s4: Add 7g of intermediate 3 and 20mL of deionized water to a three-necked flask, and adjust the pH of the mixture to 3.5 using a 20% sodium hydroxide aqueous solution. Heat to 70℃ and stir for 10min. Add 0.8g of potassium persulfate to the flask and stir for 15min. Add 10g of intermediate 2 to the flask and continue stirring for 30min. Rinse with deionized water and dry to obtain intermediate 4.

[0055] Step s5: Add 20g of intermediate 2 and 25g of ammonium polyphosphate CF-IFR to a three-necked flask equipped with a stirrer, thermometer and reflux condenser. Stir for 1 hour at 25℃ and 200r / min. Then, while stirring, raise the temperature to reflux, add deionized water and continue stirring for 5 hours. After the reaction is completed, neutralize with sodium bicarbonate at 40℃ for 10 minutes, rinse 3 times with deionized water, and dry at 80℃ to obtain the modified flame retardant.

[0056] Step s6: Add 0.15g agarose LP0028A, 0.1g polyvinyl alcohol PVA2488, and 100mL deionized water to a glass container. Heat and stir in a magnetically stirred water bath at 85℃ and 300r / min for 10min. Add 3g LBF-aerogel to 50mL ethanol, mix and stir, and then add to the above polymer aqueous solution. Heat and stir in a magnetically stirred water bath at 85℃ and 500r / min for 1h. Then add dropwise to 201 methyl silicone oil and stir at 1000r / min for 30min. Centrifuge and wash 4 times with ethanol and water to obtain modified aerogel for later use.

[0057] Step s7: Add 5 mL of wetting agent ND1096, 5 mL of dispersant BYK-U80, 15 mL of compatibilizer POE, 5 mL of defoamer PX-122, 10 mL of bactericide LXE, and 15 mL of thickener AT50 to 100 mL of deionized water in sequence, and stir at 500 r / min for 20 min. Then add 10 g of rutile TiO2 PTT-P20, 5 g of hollow glass microspheres K46, and 5 g of modified aerogel in sequence, and stir at 2500 r / min for 30 min. Add 10 mL of film-forming aid TEXANOL and 15 mL of pure acrylic emulsion BA-201 to the solution, and stir at 2500 r / min for 60 min to obtain the modified composite heat insulation coating.

[0058] Step s8: Place 10g of urea in a muffle furnace and heat at 550℃ for 4h at a heating rate of 2℃ / min to obtain carbon nitride. After cooling at room temperature, grind it into powder using an agate mortar. Add 1g of red phosphorus to 60mL of deionized water and hydrothermally treat it in a reaction vessel at 200℃ for 12h to obtain amorphous phosphorus powder for later use.

[0059] Step s9: Add 500mg of carbon nitride and 200mg of amorphous phosphorus powder to the slurry and grind them. Transfer the resulting powder to a quartz ampoule and seal it with an oxyhydrogen flame under a low vacuum of 100Pa. Heat the ampoule in a furnace at 400℃ for 4 hours at a heating rate of 2℃ / min. After slowly cooling to room temperature, break the capsule and wash it with CS2, ethanol and distilled water respectively to obtain red phosphorus carbon nitride.

[0060] Step s10: Add 2g of red phosphorus carbon nitride to 495g of pure viscose spinning solution with a cellulose content of 8.9%, stir for 2 hours, place it in a vacuum oven for degassing at -25KPa for 4 hours, then add it to the spinning equipment, press it into the coagulation bath under a pressure of 2MPa, and spun out through a 300-hole spinneret. The fiber then enters the coagulation bath, followed by a weak acid bath, then a stretching bath, and finally a 200mL sodium hydroxide solution (1% by mass) for alkaline washing. Finally, it is washed with deionized water. The spun fiber is dried under vacuum at 50℃ to obtain modified viscose fiber. The coagulation bath consists of a mixed solution of 12g / L ZnSO4, 270g / L Na2SO4, and 130g / L H2SO4; the weak acid bath consists of a mixed solution of 4g / L ZnSO4, 90g / L Na2SO4, and 43g / L H2SO4; and the stretching bath is deionized water.

[0061] Step s11: Weigh out 40 parts of nylon 66 granules, 5 parts of modified flame retardant, 5 parts of modified composite heat insulation coating, 20 parts of modified viscose fiber, 10 parts of glass fiber, 0.5 parts of coupling agent KH550, 0.2 parts of antioxidant 10100, and 1 part of nano-grade titanium dioxide according to the weight composition, and set aside.

[0062] Step s12: Nylon 66 particles, nano-sized titanium dioxide, modified flame retardant, antioxidant 1010, and coupling agent KH550 are added to a high-speed mixer at 1500 r / min and mixed evenly. Then, the mixture is added to a twin-screw extruder at 240°C for melt extrusion. The mixture is then added to an electrostatic spinning machine for spinning into yarn. The yarn is then added together with modified viscose fiber and glass fiber to an opening and blending equipment for even mixing. Finally, the yarn is added to a vortex spinning machine for spinning to obtain yarn.

[0063] Step s13: Immerse the yarn in a 5% (w / w) γ-aminopropyltriethoxysilane solution for 20 min, wash with water, and dry at 80°C. Then immerse it in a 2% (w / w) phytic acid solution for 10 min, wash with water, and dry at 80°C. Repeat this process 5 times. Then, immerse the formed yarn in an impregnation tank containing a modified composite heat-insulating coating for 20 min. The bath ratio of the yarn to the γ-aminopropyltriethoxysilane solution, phytic acid solution, and modified composite heat-insulating coating is 1:10:10:10. Finally, put the yarn into a 90°C oven for drying and curing to obtain a heat-insulating and flame-retardant yarn.

[0064] Example 2:

[0065] This embodiment describes a method for preparing heat-insulating and flame-retardant yarn, including the following steps:

[0066] Step s1: Add 20g of citric acid and 90mL of dichloromethane to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. Stir at 400r / min, add 3g of sodium hypophosphite, transfer to constant pressure dropping funnel, cool to 3℃ and maintain low temperature stirring for 1h, heat to 83℃ and stir at 400r / min for 6h, extract, wash and dry, remove solvent by vacuum distillation to obtain intermediate 1;

[0067] Step s2: Add 23g of intermediate 1, 4g of guar gum and 200mL of deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 40min at 55℃ and 400r / min. Add 3g of sodium hypophosphite and transfer to a constant pressure dropping funnel. Stir for 2h. Raise the temperature to 83℃ and stir at 500r / min for 6h. After the reaction is complete, cool the reaction product to room temperature, let it stand to precipitate, and dry to obtain intermediate 2.

[0068] Step s3: Add 9.3g of diethyl chlorophosphate and 50mL of tetrahydrofuran to a three-necked flask, purge with nitrogen and maintain the temperature at 3°C. Dissolve 8.8g of methacrylamide in 50mL of tetrahydrofuran and add it dropwise to the three-necked flask. Then add 5.3g of triethylamine to the three-necked flask, raise the temperature to 38°C, and react for 11h. Remove the solvent by rotary evaporation to obtain intermediate 3.

[0069] Step s4: Add 7.5g of intermediate 3 and 23mL of deionized water to a three-necked flask, and adjust the pH of the mixture to 3.5 using a 20% sodium hydroxide aqueous solution. Heat to 70℃ and stir for 10min. Add 0.9g of potassium persulfate to the flask and stir for 15min. Add 13g of intermediate 2 to the flask and continue stirring for 30min. Rinse with deionized water and dry to obtain intermediate 4.

[0070] Step s5: Add 23g of intermediate 2 and 28g of ammonium polyphosphate CF-IFR to a three-necked flask equipped with a stirrer, thermometer and reflux condenser. Stir for 1.3h at 28℃ and 200r / min. Then, while stirring, raise the temperature to reflux, add deionized water and continue stirring for 5h. After the reaction is completed, neutralize with sodium bicarbonate at 40℃ for 10min, rinse 3 times with deionized water, and dry at 80℃ to obtain the modified flame retardant.

[0071] Step s6: Add 0.6g agarose LP0028A, 0.5g polyvinyl alcohol PVA2488, and 100mL deionized water to a glass container. Heat and stir in a magnetically stirred water bath at 85℃ and 300r / min for 20min. Add 3g LBF-aerogel to 50mL ethanol, mix and stir, and then add to the above polymer aqueous solution. Heat and stir in a magnetically stirred water bath at 85℃ and 750r / min for 1.5h. Then add dropwise to 201 methyl silicone oil and stir at 1000r / min for 35min. Centrifuge and wash 4 times with ethanol and water to obtain modified aerogel for later use.

[0072] Step s7: Add 8 mL of wetting agent ND1096, 8 mL of dispersant BYK-U80, 15 mL of compatibilizer POE, 5 mL of defoamer PX-122, 10 mL of bactericide LXE, and 15 mL of thickener AT50 to 100 mL of deionized water in sequence, and stir at 750 r / min for 25 min. Then add 10 g of rutile TiO2 PTT-P20, 15 g of hollow glass microspheres K46, and 18 g of modified aerogel in sequence, and stir at 2750 r / min for 35 min. Add 10 mL of film-forming aid TEXANOL and 15 mL of pure acrylic emulsion BA-201 to the solution, and stir at 2500 r / min for 70 min to obtain the modified composite heat insulation coating.

[0073] Step s8: Place 13g of urea in a muffle furnace and heat at 550℃ for 5h at a heating rate of 2℃ / min to obtain carbon nitride. After cooling at room temperature, grind it into powder using an agate mortar. Add 1.5g of red phosphorus to 70mL of deionized water and hydrothermally treat it in a reaction vessel at 200℃ for 13h to obtain amorphous phosphorus powder for later use.

[0074] Step s9: Add 500mg of carbon nitride and 200mg of amorphous phosphorus powder to slurry and grind them. Transfer the resulting powder to a quartz ampoule and seal it with an oxyhydrogen flame under a low vacuum of 550Pa. Heat the ampoule in a furnace at 475℃ for 4 hours at a heating rate of 2℃ / min. After slowly cooling to room temperature, break the capsule and wash it with CS2, ethanol and distilled water respectively to obtain red phosphorus carbon nitride.

[0075] Step s10: Add 3g of red phosphorus carbon nitride to 498g of pure viscose spinning solution with a cellulose content of 8.9%, stir for 2.5h, place it in a vacuum oven for degassing at -25KPa for 4.5h, then add it to the spinning equipment, extrude it into the coagulation bath under a pressure of 2MPa, and spun out through a 300-hole spinneret, entering the coagulation bath, then the weak acid bath, then the stretching bath, and then alkali washing with 200mL of 1% sodium hydroxide solution. Finally, wash with deionized water, and dry the spun fiber under vacuum at 50℃ to obtain modified viscose fiber; the coagulation bath is a mixed solution of 12g / L ZnSO4, 270g / L Na2SO4, and 130g / L H2SO4; the weak acid bath is a mixed solution of 4g / L ZnSO4, 90g / L Na2SO4, and 43g / L H2SO4; the stretching bath is deionized water;

[0076] Step s11: Weigh out 50 parts of nylon 66 granules, 10 parts of modified flame retardant, 10 parts of modified composite heat insulation coating, 28 parts of modified viscose fiber, 15 parts of glass fiber, 1.3 parts of coupling agent KH550, 0.4 parts of antioxidant 10100, and 2 parts of nano-grade titanium dioxide according to the weight composition, and set aside.

[0077] Step s12: Nylon 66 particles, nano-sized titanium dioxide, modified flame retardant, antioxidant 1010, and coupling agent KH550 are added to a high-speed mixer at 2250 r / min and mixed evenly. Then, the mixture is added to a twin-screw extruder at 250°C for melt extrusion. The mixture is then added to an electrostatic spinning machine for spinning into yarn. After being mixed evenly with modified viscose fiber and glass fiber, the yarn is added to an opening and blending equipment and then added to a vortex spinning machine for spinning to obtain yarn.

[0078] Step s13: Immerse the yarn in a 5% (w / w) γ-aminopropyltriethoxysilane solution for 25 min, wash with water, and dry at 80°C. Then immerse it in a 2% (w / w) phytic acid solution for 15 min, wash with water, and dry at 80°C. Repeat this process 8 times. Then, immerse the formed yarn in an impregnation tank containing a modified composite heat-insulating coating for 25 min. The bath ratio of the yarn to the γ-aminopropyltriethoxysilane solution, phytic acid solution, and modified composite heat-insulating coating is 1:10:13:10. Finally, place the yarn in an oven at 110°C for drying and curing to obtain a heat-insulating and flame-retardant yarn.

[0079] Example 3:

[0080] This embodiment describes a method for preparing heat-insulating and flame-retardant yarn, including the following steps:

[0081] Step s1: Add 25g of citric acid and 100mL of dichloromethane to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. Stir at 450r / min, add 5g of sodium hypophosphite, transfer to constant pressure dropping funnel, cool to 5℃ and maintain low temperature stirring for 1h, heat to 85℃ and stir at 450r / min for 7h, extract, wash and dry, remove solvent by vacuum distillation to obtain intermediate 1;

[0082] Step s2: Add 25g of intermediate 1, 5g of guar gum and 200mL of deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 50min at 60℃ and 450r / min. Add 5g of sodium hypophosphite and transfer to a constant pressure dropping funnel. Stir for 3h. Raise the temperature to 85℃ and stir at 500r / min for 6h. After the reaction is complete, cool the reaction product to room temperature, let it stand to precipitate, and dry to obtain intermediate 2.

[0083] Step s3: Add 9.5g of diethyl chlorophosphate and 50mL of tetrahydrofuran to a three-necked flask, purge with nitrogen for protection, and maintain the temperature at 5℃. Dissolve 9g of methacrylamide in 50mL of tetrahydrofuran and add it dropwise to the three-necked flask. Then add 5.5g of triethylamine to the three-necked flask, raise the temperature to 40℃, and react for 12h. Remove the solvent by rotary evaporation to obtain intermediate 3.

[0084] Step s4: Add 8g of intermediate 3 and 25mL of deionized water to a three-necked flask, and adjust the pH of the mixture to 3.5 using a 20% sodium hydroxide aqueous solution. Heat to 70℃ and stir for 10min. Add 1g of potassium persulfate to the flask and stir for 15min. Add 15g of intermediate 2 to the flask and continue stirring for 30min. Rinse with deionized water and dry to obtain intermediate 4.

[0085] Step s5: Add 25g of intermediate 2 and 30g of ammonium polyphosphate CF-IFR to a three-necked flask equipped with a stirrer, thermometer and reflux condenser. Stir for 1.5h at 30℃ and 200r / min. Then, while stirring, raise the temperature to reflux, add deionized water and continue stirring for 5h. After the reaction is completed, neutralize with sodium bicarbonate at 40℃ for 10min, rinse 4 times with deionized water, and dry at 80℃ to obtain the modified flame retardant.

[0086] Step s6: Add 1g agarose LP0028A, 0.9g polyvinyl alcohol PVA2488, and 100mL deionized water to a glass container. Heat and stir in a magnetically stirred water bath at 85℃ and 300r / min for 30min. Add 3g LBF-aerogel to 50mL ethanol, mix and stir, and then add to the above polymer aqueous solution. Heat and stir in a magnetically stirred water bath at 85℃ and 1000r / min for 2h. Then add dropwise to 201 methyl silicone oil and stir at 1000r / min for 40min. Centrifuge and wash 5 times with ethanol and water to obtain modified aerogel for later use.

[0087] Step s7: Add 10 mL of wetting agent ND1096, 10 mL of dispersant BYK-U80, 15 mL of compatibilizer POE, 5 mL of defoamer PX-122, 10 mL of bactericide LXE, and 15 mL of thickener AT50 to 100 mL of deionized water in sequence, and stir at 1000 r / min for 30 min. Then add 10 g of rutile TiO2 PTT-P20, 25 g of hollow glass microspheres K46, and 30 g of modified aerogel in sequence, and stir at 3000 r / min for 40 min. Add 10 mL of film-forming aid TEXANOL and 15 mL of pure acrylic emulsion BA-201 to the solution, and stir at 2500 r / min for 80 min to obtain the modified composite heat insulation coating.

[0088] Step s8: Place 15g of urea in a muffle furnace and heat at 550℃ for 6h at a heating rate of 2℃ / min to obtain carbon nitride. After cooling at room temperature, grind it into powder using an agate mortar. Add 2g of red phosphorus to 80mL of deionized water and hydrothermally treat it in a reaction vessel at 200℃ for 14h to obtain amorphous phosphorus powder for later use.

[0089] Step s9: Add 500mg of carbon nitride and 200mg of amorphous phosphorus powder to the slurry and grind them. Transfer the resulting powder to a quartz ampoule and seal it with an oxyhydrogen flame under a low vacuum of 1000Pa. Heat the ampoule in a furnace at 550℃ for 4 hours at a heating rate of 2℃ / min. After slowly cooling to room temperature, break the capsule and wash it with CS2, ethanol and distilled water respectively to obtain red phosphorus carbon nitride.

[0090] Step s10: Add 4g of red phosphorus carbon nitride to 500g of pure viscose spinning solution with a cellulose content of 8.9%, stir for 3 hours, place it in a vacuum oven for degassing at -25KPa for 5 hours, then add it to the spinning equipment, extrude it into the coagulation bath under a pressure of 2MPa, and spun out through a 300-hole spinneret, entering the coagulation bath, then the weak acid bath, then the stretching bath, and then alkali washing with 200mL of 1% sodium hydroxide solution. Finally, wash with deionized water, and dry the spun fiber under vacuum at 50℃ to obtain modified viscose fiber; the coagulation bath is a mixed solution of 12g / L ZnSO4, 270g / L Na2SO4, and 130g / L H2SO4; the weak acid bath is a mixed solution of 4g / L ZnSO4, 90g / L Na2SO4, and 43g / L H2SO4; the stretching bath is deionized water;

[0091] Step s11: Weigh out 60 parts of nylon 66 granules, 15 parts of modified flame retardant, 15 parts of modified composite heat insulation coating, 35 parts of modified viscose fiber, 20 parts of glass fiber, 2 parts of coupling agent KH550, 0.5 parts of antioxidant 10100, and 3 parts of nano-grade titanium dioxide according to the weight composition, and set aside.

[0092] Step s12: Nylon 66 particles, nano-sized titanium dioxide, modified flame retardant, antioxidant 1010, and coupling agent KH550 are added to a high-speed mixer at 3000 r / min and mixed evenly. Then, the mixture is added to a twin-screw extruder at 260°C for melt extrusion. The mixture is then added to an electrostatic spinning machine for spinning into yarn. After being mixed evenly with modified viscose fiber and glass fiber, the yarn is added to an opening and blending equipment and then added to a vortex spinning machine for spinning to obtain yarn.

[0093] Step s13: Immerse the yarn in a 5% (w / w) γ-aminopropyltriethoxysilane solution for 30 min, wash with water, and dry at 80°C. Then immerse it in a 2% (w / w) phytic acid solution for 20 min, wash with water, and dry at 80°C. Repeat this process 10 times. Then, immerse the formed yarn in an impregnation tank containing a modified composite heat-insulating coating for 30 min. The bath ratio of the yarn to the γ-aminopropyltriethoxysilane solution, phytic acid solution, and modified composite heat-insulating coating is 1:10:15:10. Finally, place the yarn in an oven at 130°C for drying and curing to obtain a heat-insulating and flame-retardant yarn.

[0094] Comparative Example 1:

[0095] This comparative example illustrates a method for preparing a heat-insulating and flame-retardant yarn, comprising the following steps:

[0096] Step s1: Weigh out 50 parts of nylon 66 granules, 15 parts of glass fiber, 1.3 parts of coupling agent KH550, 0.4 parts of antioxidant 10100, and 2 parts of nano-sized titanium dioxide according to the weight composition, and set aside.

[0097] Step s2: Nylon 66 particles, nano-sized titanium dioxide, antioxidant 1010, and coupling agent KH550 are added to a high-speed mixer at 2250 r / min and mixed evenly. Then, the mixture is added to a twin-screw extruder at 250°C for melt extrusion. The mixture is then added to an electrostatic spinning machine for spinning into yarn. Finally, the yarn is added to an opening and blending equipment along with glass fiber and mixed evenly. The yarn is then added to a vortex spinning machine for spinning to obtain yarn.

[0098] Step s3: Immerse the yarn in a 5% (w / w) γ-aminopropyltriethoxysilane solution for 25 min, wash with water, and dry at 80°C. Then immerse it in a 2% (w / w) phytic acid solution for 15 min, wash with water, and dry at 80°C. Repeat this process 8 times. The ratio of the yarn to the γ-aminopropyltriethoxysilane solution and the phytic acid solution is 1:10:13. Then, put the yarn into an oven at 110°C for drying and curing to obtain heat-insulating and flame-retardant yarn.

[0099] Comparative Example 2:

[0100] This comparative example illustrates a method for preparing a heat-insulating and flame-retardant yarn, comprising the following steps:

[0101] Step s1: Add 20g of citric acid and 90mL of dichloromethane to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. Stir at 400r / min, add 3g of sodium hypophosphite, transfer to constant pressure dropping funnel, cool to 3℃ and maintain low temperature stirring for 1h, heat to 83℃ and stir at 400r / min for 6h, extract, wash and dry, remove solvent by vacuum distillation to obtain intermediate 1;

[0102] Step s2: Add 23g of intermediate 1, 4g of guar gum and 200mL of deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 40min at 55℃ and 400r / min. Add 3g of sodium hypophosphite and transfer to a constant pressure dropping funnel. Stir for 2h. Raise the temperature to 83℃ and stir at 500r / min for 6h. After the reaction is complete, cool the reaction product to room temperature, let it stand to precipitate, and dry to obtain intermediate 2.

[0103] Step s3: Add 9.3g of diethyl chlorophosphate and 50mL of tetrahydrofuran to a three-necked flask, purge with nitrogen and maintain the temperature at 3°C. Dissolve 8.8g of methacrylamide in 50mL of tetrahydrofuran and add it dropwise to the three-necked flask. Then add 5.3g of triethylamine to the three-necked flask, raise the temperature to 38°C, and react for 11h. Remove the solvent by rotary evaporation to obtain intermediate 3.

[0104] Step s4: Add 7.5g of intermediate 3 and 23mL of deionized water to a three-necked flask, and adjust the pH of the mixture to 3.5 using a 20% sodium hydroxide aqueous solution. Heat to 70℃ and stir for 10min. Add 0.9g of potassium persulfate to the flask and stir for 15min. Add 13g of intermediate 2 to the flask and continue stirring for 30min. Rinse with deionized water and dry to obtain intermediate 4.

[0105] Step s5: Add 23g of intermediate 2 and 28g of ammonium polyphosphate CF-IFR to a three-necked flask equipped with a stirrer, thermometer and reflux condenser. Stir for 1.3h at 28℃ and 200r / min. Then, while stirring, raise the temperature to reflux, add deionized water and continue stirring for 5h. After the reaction is completed, neutralize with sodium bicarbonate at 40℃ for 10min, rinse 3 times with deionized water, and dry at 80℃ to obtain the modified flame retardant.

[0106] Step s6: Weigh out 50 parts of nylon 66 granules, 10 parts of modified flame retardant, 15 parts of glass fiber, 1.3 parts of coupling agent KH550, 0.4 parts of antioxidant 10100, and 2 parts of nano-grade titanium dioxide according to the weight composition, and set aside.

[0107] Step s7: Nylon 66 particles, nano-sized titanium dioxide, modified flame retardant, antioxidant 1010, and coupling agent KH550 are added to a high-speed mixer at 2250 r / min and mixed evenly. Then, the mixture is added to a twin-screw extruder at 250°C for melt extrusion. The mixture is then added to an electrostatic spinning machine for spinning into yarn. Finally, the yarn is added together with glass fiber to an opening and blending equipment for even mixing. The mixture is then added to a vortex spinning machine for spinning to obtain yarn.

[0108] Step s8: Immerse the yarn in a 5% (w / w) γ-aminopropyltriethoxysilane solution for 25 min, wash with water, and dry at 80°C. Then immerse it in a 2% (w / w) phytic acid solution for 15 min, wash with water, and dry at 80°C. Repeat this process 8 times. The ratio of the yarn to the γ-aminopropyltriethoxysilane solution and the phytic acid solution is 1:10:13. Then, put the yarn into an oven at 110°C for drying and curing to obtain heat-insulating and flame-retardant yarn.

[0109] Comparative Example 3:

[0110] This comparative example illustrates a method for preparing a heat-insulating and flame-retardant yarn, comprising the following steps:

[0111] Step s1: Add 20g of citric acid and 90mL of dichloromethane to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. Stir at 400r / min, add 3g of sodium hypophosphite, transfer to constant pressure dropping funnel, cool to 3℃ and maintain low temperature stirring for 1h, heat to 83℃ and stir at 400r / min for 6h, extract, wash and dry, remove solvent by vacuum distillation to obtain intermediate 1;

[0112] Step s2: Add 23g of intermediate 1, 4g of guar gum and 200mL of deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 40min at 55℃ and 400r / min. Add 3g of sodium hypophosphite and transfer to a constant pressure dropping funnel. Stir for 2h. Raise the temperature to 83℃ and stir at 500r / min for 6h. After the reaction is complete, cool the reaction product to room temperature, let it stand to precipitate, and dry to obtain intermediate 2.

[0113] Step s3: Add 9.3g of diethyl chlorophosphate and 50mL of tetrahydrofuran to a three-necked flask, purge with nitrogen and maintain the temperature at 3°C. Dissolve 8.8g of methacrylamide in 50mL of tetrahydrofuran and add it dropwise to the three-necked flask. Then add 5.3g of triethylamine to the three-necked flask, raise the temperature to 38°C, and react for 11h. Remove the solvent by rotary evaporation to obtain intermediate 3.

[0114] Step s4: Add 7.5g of intermediate 3 and 23mL of deionized water to a three-necked flask, and adjust the pH of the mixture to 3.5 using a 20% sodium hydroxide aqueous solution. Heat to 70℃ and stir for 10min. Add 0.9g of potassium persulfate to the flask and stir for 15min. Add 13g of intermediate 2 to the flask and continue stirring for 30min. Rinse with deionized water and dry to obtain intermediate 4.

[0115] Step s5: Add 23g of intermediate 2 and 28g of ammonium polyphosphate CF-IFR to a three-necked flask equipped with a stirrer, thermometer and reflux condenser. Stir for 1.3h at 28℃ and 200r / min. Then, while stirring, raise the temperature to reflux, add deionized water and continue stirring for 5h. After the reaction is completed, neutralize with sodium bicarbonate at 40℃ for 10min, rinse 3 times with deionized water, and dry at 80℃ to obtain the modified flame retardant.

[0116] Step s6: Add 0.6g agarose LP0028A, 0.5g polyvinyl alcohol PVA2488, and 100mL deionized water to a glass container. Heat and stir in a magnetically stirred water bath at 85℃ and 300r / min for 20min. Add 3g LBF-aerogel to 50mL ethanol, mix and stir, and then add to the above polymer aqueous solution. Heat and stir in a magnetically stirred water bath at 85℃ and 750r / min for 1.5h. Then add dropwise to 201 methyl silicone oil and stir at 1000r / min for 35min. Centrifuge and wash 4 times with ethanol and water to obtain modified aerogel for later use.

[0117] Step s7: Add 8 mL of wetting agent ND1096, 8 mL of dispersant BYK-U80, 15 mL of compatibilizer POE, 5 mL of defoamer PX-122, 10 mL of bactericide LXE, and 15 mL of thickener AT50 to 100 mL of deionized water in sequence, and stir at 750 r / min for 25 min. Then add 10 g of rutile TiO2 PTT-P20, 15 g of hollow glass microspheres K46, and 18 g of modified aerogel in sequence, and stir at 2750 r / min for 35 min. Add 10 mL of film-forming aid TEXANOL and 15 mL of pure acrylic emulsion BA-201 to the solution, and stir at 2500 r / min for 70 min to obtain the modified composite heat insulation coating.

[0118] Step s8: Weigh out 50 parts of nylon 66 granules, 10 parts of modified flame retardant, 10 parts of modified composite heat insulation coating, 15 parts of glass fiber, 1.3 parts of coupling agent KH550, 0.4 parts of antioxidant 10100, and 2 parts of nano-grade titanium dioxide according to the weight composition, and set aside.

[0119] Step s9: Nylon 66 particles, nano-sized titanium dioxide, modified flame retardant, antioxidant 1010, and coupling agent KH550 are added to a high-speed mixer at 2250 r / min and mixed evenly. Then, the mixture is added to a twin-screw extruder at 250°C for melt extrusion. The mixture is then added to an electrostatic spinning machine for spinning into yarn. Finally, the yarn is added together with glass fiber to an opening and blending equipment for even mixing. The mixture is then added to a vortex spinning machine for spinning to obtain yarn.

[0120] Step s10: Immerse the yarn in a 5% (w / w) γ-aminopropyltriethoxysilane solution for 25 min, wash with water, and dry at 80°C. Then immerse it in a 2% (w / w) phytic acid solution for 15 min, wash with water, and dry at 80°C. Repeat this process 8 times. Then, immerse the formed yarn in an impregnation tank containing a modified composite heat-insulating coating for 25 min. The bath ratio of the yarn to the γ-aminopropyltriethoxysilane solution, phytic acid solution, and modified composite heat-insulating coating is 1:10:13:10. Finally, put the yarn into an oven at 110°C for drying and curing to obtain a heat-insulating and flame-retardant yarn.

[0121] Comparative Example 4:

[0122] This comparative example illustrates a method for preparing a heat-insulating and flame-retardant yarn, including the following steps:

[0123] Step s1: Add 0.6g agarose LP0028A, 0.5g polyvinyl alcohol PVA2488, and 100mL deionized water to a glass container. Heat and stir in a magnetically stirred water bath at 85℃ and 300r / min for 20min. Add 3g LBF-aerogel to 50mL ethanol, mix and stir, and then add to the above polymer aqueous solution. Heat and stir in a magnetically stirred water bath at 85℃ and 750r / min for 1.5h. Then add dropwise to 201 methyl silicone oil and stir at 1000r / min for 35min. Centrifuge and wash 4 times with ethanol and water to obtain modified aerogel for later use.

[0124] Step s2: Add 8 mL of wetting agent ND1096, 8 mL of dispersant BYK-U80, 15 mL of compatibilizer POE, 5 mL of defoamer PX-122, 10 mL of bactericide LXE, and 15 mL of thickener AT50 to 100 mL of deionized water in sequence, and stir at 750 r / min for 25 min. Then add 10 g of rutile TiO2 PTT-P20, 15 g of hollow glass microspheres K46, and 18 g of modified aerogel in sequence, and stir at 2750 r / min for 35 min. Add 10 mL of film-forming aid TEXANOL and 15 mL of pure acrylic emulsion BA-201 to the solution, and stir at 2500 r / min for 70 min to obtain the modified composite heat insulation coating.

[0125] Step s3: Place 13g of urea in a muffle furnace and heat at 550℃ for 5h at a heating rate of 2℃ / min to obtain carbon nitride. After cooling at room temperature, grind it into powder using an agate mortar. Add 1.5g of red phosphorus to 70mL of deionized water and hydrothermally treat it in a reaction vessel at 200℃ for 13h to obtain amorphous phosphorus powder for later use.

[0126] Step s4: Add 500mg of carbon nitride and 200mg of amorphous phosphorus powder to the slurry and grind them. Transfer the resulting powder to a quartz ampoule and seal it with an oxyhydrogen flame under a low vacuum of 550Pa. Heat the ampoule in a furnace at 475℃ for 4 hours at a heating rate of 2℃ / min. After slowly cooling to room temperature, break the capsule and wash it with CS2, ethanol and distilled water respectively to obtain red phosphorus carbon nitride.

[0127] Step s5: Add 3g of red phosphorus carbon nitride to 498g of pure viscose spinning solution with a cellulose content of 8.9%, stir for 2.5h, place it in a vacuum oven for degassing at -25KPa for 4.5h, then add it to the spinning equipment, extrude it into the coagulation bath under a pressure of 2MPa, and spun out through a 300-hole spinneret. The fiber then enters the coagulation bath, followed by a weak acid bath, then a stretching bath, and finally a 200mL sodium hydroxide solution (1% by mass) for alkaline washing. Finally, it is washed with deionized water. The spun fiber is dried under vacuum at 50℃ to obtain modified viscose fiber. The coagulation bath consists of a mixed solution of 12g / L ZnSO4, 270g / L Na2SO4, and 130g / L H2SO4; the weak acid bath consists of a mixed solution of 4g / L ZnSO4, 90g / L Na2SO4, and 43g / L H2SO4; and the stretching bath is deionized water.

[0128] Step s6: Weigh out 50 parts of nylon 66 granules, 10 parts of modified composite heat insulation coating, 28 parts of modified viscose fiber, 15 parts of glass fiber, 1.3 parts of coupling agent KH550, 0.4 parts of antioxidant 10100, and 2 parts of nano-grade titanium dioxide according to the weight composition, and set aside.

[0129] Step s7: Nylon 66 particles, nano-sized titanium dioxide, antioxidant 1010, and coupling agent KH550 are added to a high-speed mixer at 2250 r / min and mixed evenly. Then, the mixture is added to a twin-screw extruder at 250°C for melt extrusion. The mixture is then added to an electrostatic spinning machine for spinning into yarn. After being mixed evenly with modified viscose fiber and glass fiber, the yarn is added to a vortex spinning machine for spinning to obtain yarn.

[0130] Step s8: Immerse the yarn in a 5% (w / w) γ-aminopropyltriethoxysilane solution for 25 min, wash with water, and dry at 80°C. Then immerse it in a 2% (w / w) phytic acid solution for 15 min, wash with water, and dry at 80°C. Repeat this process 8 times. Then, immerse the formed yarn in an impregnation tank containing a modified composite heat-insulating coating for 25 min. The bath ratio of the yarn to the γ-aminopropyltriethoxysilane solution, phytic acid solution, and modified composite heat-insulating coating is 1:10:13:10. Finally, place the yarn in an oven at 110°C for drying and curing to obtain a heat-insulating and flame-retardant yarn.

[0131] The heat-insulating and flame-retardant yarns of Examples 1-3 and Comparative Examples 1-4 were tested according to GB / T41560-2022 "Determination of Heat-Shielding Performance of Textiles"; GB17591-2006 "Flame-Retardant Fabrics"; and GB20286-2006 "Determination of Oxygen Index of Textiles". The test results are shown in the table below:

[0132]

[0133] Referring to the table above, it can be seen that the heat-insulating and flame-retardant yarn of the present invention has excellent heat-insulating and flame-retardant effects. The heat-shielding performance of Examples 1-3 is greater than 0.38, with obvious heat insulation effect. The oxygen index is greater than 27%, and the vertical burning damage length is less than 80mm. The material is more difficult to ignite or self-spread in a fire, and has strong flame-retardant performance. Materials with an oxygen index of 27% or higher usually have self-extinguishing properties, that is, they can extinguish themselves after leaving the fire source. According to the comparison between Examples 1-3 and Comparative Examples 1-4, it can be seen that adding modified flame retardants and modified viscose fibers can significantly improve the flame-retardant ability of the yarn, and adding modified composite heat-insulating coatings can significantly improve the heat insulation performance of the yarn.

[0134] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0135] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a heat-insulating and flame-retardant yarn, characterized in that, Includes the following steps: Step 1: Weigh out the following components by weight: 40-60 parts nylon 66 granules, 5-15 parts modified flame retardant, 5-15 parts modified composite heat insulation coating, 20-35 parts modified viscose fiber, 10-20 parts glass fiber, 0.5-2 parts coupling agent, 0.2-0.5 parts antioxidant, and 1-3 parts nano-grade titanium dioxide. Step 2: Mix Nylon 66 particles, nano-sized titanium dioxide, modified flame retardant, antioxidant, and coupling agent evenly, then melt-extrude the mixture and add it to an electrospinning machine for spinning. Then, mix it with modified viscose fiber and glass fiber to obtain yarn. Step 3: Impregnate the yarn in γ-aminopropyltriethoxysilane solution, wash with water, and dry. Then impregnate it in phytic acid solution, wash with water, and dry. Repeat this process. Impregnate the formed yarn in modified composite heat-insulating coating, and then dry and cure the yarn to obtain heat-insulating and flame-retardant yarn. The modified flame retardant is prepared by the following steps: Step a1: Add citric acid and dichloromethane to a flask and stir. Add sodium hypophosphite, transfer to a constant pressure dropping funnel, stir, extract, wash and dry, and distill under reduced pressure to obtain intermediate 1. Step a2: Add intermediate 1, guar gum, and deionized water to a flask and stir. Add sodium hypophosphite, transfer to a constant pressure dropping funnel, stir, let stand to precipitate, and dry to obtain intermediate 2. Step a3: Dissolve diethyl chlorophosphate in tetrahydrofuran under nitrogen protection, dissolve methacrylamide in tetrahydrofuran and add it dropwise to the above solution, add triethylamine, and rotary evaporate to obtain intermediate 3; Step a4: Add intermediate 3 and deionized water to the flask, heat and stir, add potassium persulfate and intermediate 2 to the flask and stir, wash and dry to obtain intermediate 4; Step a5: Add intermediate 2 and ammonium polyphosphate to a flask and stir. While stirring, heat and reflux, neutralize with sodium bicarbonate, rinse, and dry to obtain the modified flame retardant.

2. The method for preparing a heat-insulating and flame-retardant yarn according to claim 1, characterized in that, The coupling agent in step one is coupling agent KH550; the antioxidant is antioxidant 1010; the bath ratio of the yarn to the γ-aminopropyltriethoxysilane solution, phytic acid solution and modified composite heat insulation coating in step three is 1:10:10-15:10; the mass fraction of the γ-aminopropyltriethoxysilane solution is 5%, and the mass fraction of the phytic acid solution is 2%.

3. The method for preparing a heat-insulating and flame-retardant yarn according to claim 1, characterized in that, The ratio of citric acid, dichloromethane, and sodium hypophosphite in step a1 is 15-25g: 80-100mL: 1-5g; the ratio of intermediate 1, guar gum, deionized water, and sodium hypophosphite in step a2 is 20-25g: 3-5g: 200mL: 1-5g; and the ratio of diethyl chlorophosphate, tetrahydrofuran, methacrylamide, and triethylamine in step a3 is 9-9.5g: 100mL: 8.5-9g: 5-5.5g.

4. The method for preparing a heat-insulating and flame-retardant yarn according to claim 1, characterized in that, The ratio of intermediate 3, deionized water, potassium persulfate and intermediate 2 in step a4 is 7-8g: 20-25mL: 0.8-1g: 10-15g; the ratio of intermediate 2 and ammonium polyphosphate in step a5 is 20-25g: 25-30g; the ammonium polyphosphate is ammonium polyphosphate CF-IFR.

5. The method for preparing a heat-insulating and flame-retardant yarn according to claim 1, characterized in that, The modified composite thermal insulation coating is prepared by the following steps: Step b1: Add agarose, polyvinyl alcohol, and deionized water to a glass container, heat and stir in a magnetically stirred water bath, add the aerogel to ethanol, mix and stir, add to the above polymer aqueous solution, heat and stir, then dropwise add to 201 methyl silicone oil and stir, centrifuge and wash with ethanol and water to obtain modified aerogel; Step b2: Wetting agent, dispersant, compatibilizer, defoamer, bactericide and thickener are added to deionized water in sequence and stirred. TiO2, hollow glass microspheres and modified aerogel are added in sequence and stirred at high speed. Film-forming aid and pure acrylic emulsion are added to the solution and stirred at high speed to obtain modified composite heat insulation coating.

6. The method for preparing a heat-insulating and flame-retardant yarn according to claim 5, characterized in that, In step b1, the ratio of agarose, polyvinyl alcohol, deionized water, aerogel, and ethanol is 0.15-1g:0.1-0.9g:100mL:3g:50mL; the agarose is LP0028A agarose; the polyvinyl alcohol is PVA2488; and the aerogel is LBF-aerogel. In step b2, the wetting agent, dispersant, compatibilizer, defoamer, bactericide, and thickener are respectively wetting agent ND1096, dispersant BYK-U80, compatibilizer POE, defoamer PX-122, bactericide LXE, and thickener AT50.

7. The method for preparing a heat-insulating and flame-retardant yarn according to claim 5, characterized in that, The ratio of wetting agent, dispersant, compatibilizer, defoamer, bactericide, thickener and deionizer in step b2 is 5-10mL: 5-10mL: 15mL: 5mL: 10mL: 15mL: 100mL; the ratio of TiO2, hollow glass microspheres, modified aerogel, film-forming aid and pure acrylic emulsion is 10g: 5-25g: 5-30g: 10mL: 15mL; the TiO2, hollow glass microspheres, film-forming aid and pure acrylic emulsion in step b2 are respectively rutile TiO2 PTT-P20, hollow glass microspheres K46, film-forming aid TEXANOL and pure acrylic emulsion BA-201.

8. The method for preparing a heat-insulating and flame-retardant yarn according to claim 1, characterized in that, The modified viscose fiber is prepared by the following steps: Step C1: Place urea in a muffle furnace and heat it to obtain carbon nitride. After cooling at room temperature, grind it into powder using an agate mortar. Add red phosphorus to deionized water and hydrothermally treat it in a reaction vessel to obtain amorphous phosphorus powder. Step C2: Add carbon nitride and amorphous phosphorus powder to mortar and grind them. Transfer the resulting powder to a quartz ampoule and seal it with an oxyhydrogen flame under low vacuum. Heat the ampoule in a furnace and then slowly cool it to room temperature. Break the capsule and wash it with CS2, ethanol and distilled water respectively to obtain red phosphorus carbon nitride. Step C3: Add red phosphorus carbon nitride to the viscose solution, stir, put it in a vacuum oven to remove bubbles, then add it to the spinning equipment, extrude it into the coagulation bath, and spun it out through a 300-hole spinneret. It then enters the coagulation bath, followed by a weak acid bath, then a stretching bath, and then an alkaline wash in a sodium hydroxide solution. Finally, it is washed with deionized water and dried under vacuum to obtain modified viscose fiber.

9. The method for preparing a heat-insulating and flame-retardant yarn according to claim 8, characterized in that, The ratio of urea, red phosphorus, and deionized water in step c1 is 10-15g: 1-2g: 60-80mL; as a further embodiment of the present invention, the ratio of carbon nitride and amorphous phosphorus powder in step c2 is 500mg: 200mg.

10. The method for preparing a heat-insulating and flame-retardant yarn according to claim 8, characterized in that, In step c3, the ratio of red phosphorus carbon nitride to viscose solution is 2-4g:495-500g; the viscose solution is a pure viscose spinning solution with a cellulose content of 8.9%; the coagulation bath is a mixed solution of 12g / L ZnSO4, 270g / L Na2SO4, and 130g / L H2SO4; the weak acid bath is a mixed solution of 4g / L ZnSO4, 90g / L Na2SO4, and 43g / L H2SO4; and the stretching bath is deionized water.

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