A high-toughness, flame-retardant nonwoven fabric and preparation method thereof

Abstract

The present invention discloses a high-toughness, flame-retardant non-woven fabric and a preparation method thereof, and belongs to the technical field of non-woven fabric preparation. The present invention is used to solve the technical problem that the preparation process of non-woven fabric materials in the prior art is complicated, and the toughness and flame-retardant properties of non-woven fabrics need to be further improved. A high-toughness, flame-retardant non-woven fabric is obtained by alternately stacking polyurethane spinning membranes and composite polyester spinning membranes to obtain a multilayer spinning membrane with upper and lower surface layers being polyurethane spinning membranes, and then steam hot rolling the multilayer spinning membranes. The present invention synthesizes a composite polyurethane having polyethylene glycol and polysiloxane segments, and then modifies it to prepare a polyurethane fiber membrane, and then stacks it layer by layer with a composite polyester spinning membrane composed of modified polysiloxane and polyethylene terephthalate to prepare a composite non-woven fabric, which not only effectively simplifies the preparation process of the non-woven fabric, but also improves the breaking strength, tensile properties and flame-retardant properties of the non-woven fabric material.

Description

Technical Field

[0001] The invention relates to the technical field of non-woven fabric preparation, and in particular to a high-toughness, flame-retardant non-woven fabric and a preparation method thereof. Background Art

[0002] Nonwoven fabrics are textiles made of fibers bonded together physically, chemically or mechanically. They are widely used in various fields, such as household goods, industrial materials, medical and health care, etc. High-toughness, flame-retardant nonwoven fabrics have broad application prospects in many fields, such as construction, automobiles, aerospace, and personal protective equipment. This type of nonwoven fabric can maintain stability and durability under extreme conditions such as high temperature, high pressure or fire, effectively protecting the safety of people and property.

[0003] In order to improve the toughness and flame retardant properties of non-woven fabrics in the prior art, it is usually necessary to add flame retardant additives or polymer resins to the non-woven fabric material, pre-mix the flame retardant with the non-woven fabric, and then cure it through processes such as hot pressing, hot melting or dipping. However, the compatibility between the existing flame retardant additives and the polymer materials is poor, and there is a weak interface in the non-woven fabric, which leads to a decrease in the toughness of the non-woven fabric material. In addition, the existing non-woven fabrics use hot pressing, hot melting or dipping curing processes, which have the problems of complex preparation process, reduced toughness of the non-woven fabric and poor flame retardant effect.

[0004] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a high-toughness, flame-retardant non-woven fabric and a preparation method thereof, so as to solve the technical problems in the prior art that the preparation process of non-woven fabric materials is complicated and the toughness and flame-retardant properties of non-woven fabrics need to be further improved.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A high-toughness, flame-retardant nonwoven fabric, which is obtained by alternately stacking polyurethane spinning membranes and composite polyester spinning membranes to obtain a multilayer spinning membrane whose upper and lower surfaces are both polyurethane spinning membranes, and then performing steam hot rolling treatment on the multilayer spinning membrane;

[0008] The polyurethane spinning membrane is obtained by processing the following steps:

[0009] A1. Add polyethylene glycol, isophorone diisocyanate and toluene into a three-necked flask protected by nitrogen and stir. Raise the temperature of the three-necked flask to 80-90° C. and keep warm for 3-4 hours. Add hydroxyl-terminated polydimethylsiloxane into the three-necked flask and continue to keep warm for 4-6 hours. Post-treat to obtain composite polyurethane.

[0010] The synthetic reaction principle of composite polyurethane is:

[0011]

[0012] A2. Add composite polyurethane and toluene into a three-necked flask and stir evenly. Raise the temperature of the three-necked flask to 45-50° C., slowly add 3-aminopropyltriethoxysilane into the three-necked flask, and determine the residual isocyanate group by di-n-butylamine method until no isocyanate group is detected. Keep the temperature for reaction for 2-3 hours, and perform post-treatment to obtain modified polyurethane.

[0013] The synthetic reaction principle of modified polyurethane is:

[0014]

[0015] A3, adding modified polyurethane and N,N-dimethylformamide into a beaker and stirring evenly to obtain a spinning solution, and electrospinning the spinning solution to obtain a polyurethane spinning membrane;

[0016] The composite polyester spinning membrane is obtained by processing the following steps:

[0017] B1. Add polyethylene terephthalate, modified polysiloxane and hexafluoroisopropanol into a beaker, stir until the system is completely dissolved, and stand to defoam to obtain a spinning solution;

[0018] B2. The spinning solution is transferred to an electrospinning machine for electrospinning to obtain a composite polyester spinning membrane.

[0019] Furthermore, the stacking number of layers of the multilayer spinning membrane is 5 or 7.

[0020] Furthermore, in step A1, the amount ratio of polyethylene glycol, isophorone diisocyanate, toluene, and hydroxyl-terminated polydimethylsiloxane is 4g:4.5g:40mL:20g, the polyethylene glycol is polyethylene glycol 400, and the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 2000. The post-treatment operation includes: after the reaction is completed, the three-necked flask is kept warm at 80-90°C, and the solvent is evaporated under reduced pressure to obtain a composite polyurethane; in step A2, the amount ratio of the composite polyurethane and toluene is 1g:6mL, and the post-treatment operation includes: after the reaction is completed, the temperature of the three-necked flask is increased to 75-85°C, and the solvent is evaporated under reduced pressure to obtain a modified polyurethane.

[0021] Furthermore, in step A3, the amount ratio of modified polyurethane and N,N-dimethylformamide is 1g:4mL, and the electrospinning operation includes: the electrospinning operation includes: adding the spinning solution into the syringe, and installing the syringe on the injection pump of the electrospinning machine, setting the propulsion speed to 0.001mm / s, the spinning voltage to 24kV, and the spinning membrane is collected on a drum coated with aluminum foil on the surface, the distance between the drum and the electrospinning nozzle is 8cm, the air flow velocity is 12m / s, and the nitrogen content in the air flow is higher than 95%.

[0022] Furthermore, in step B1, the dosage ratio of polyethylene terephthalate, modified polysiloxane and hexafluoroisopropanol is 5g:3g:30mL; the electrospinning operation in step B2 includes: adding the spinning solution into the syringe, and installing the syringe on the injection pump of the electrospinning machine, setting the propulsion speed to 0.001mm / s, the spinning voltage to 23kV, and collecting the spinning membrane on a drum coated with aluminum foil on the surface, the distance between the drum and the electrospinning nozzle is 15cm, and the air flow velocity is 8m / s.

[0023] Further, the modified polysiloxane is processed by the following steps:

[0024] C1. Add methyldiethoxysilane, γ-chloropropylmethyldiethoxysilane, anhydrous ethanol and purified water into a three-necked flask and stir evenly. Add hydrochloric acid into the three-necked flask to adjust the pH value of the system to 3. Raise the temperature of the three-necked flask to 50-60° C., keep the temperature for reaction for 3-5 hours, and perform post-treatment to obtain polysiloxane.

[0025] The synthetic reaction principle of polysiloxane is:

[0026]

[0027] C2, adding polysiloxane and N,N-dimethylformamide to a three-necked flask and stirring until the system is dissolved, adding cyanuric acid and triethylamine to the three-necked flask, raising the temperature of the three-necked flask to 85-95°C, keeping the temperature for reaction for 8-10 hours, lowering the temperature of the three-necked flask to room temperature, filtering with suction, transferring the filtrate to a three-necked flask and stirring, adding trimethylamine aqueous solution to the three-necked flask, raising the temperature of the three-necked flask to 55-65°C, stirring for reaction for 20-22 hours, and post-treating to obtain composite polysiloxane;

[0028] The synthetic reaction principle of composite polysiloxane is:

[0029]

[0030] C3. Add the composite polysiloxane and isopropanol into a three-necked flask and stir until the system is dissolved. Add propylene alcohol and a catalyst into the three-necked flask. Increase the temperature of the three-necked flask to reflux the system. Keep the temperature to react for 6-8 hours. Post-treat to obtain the modified polysiloxane.

[0031] The synthetic reaction principle of modified polysiloxane is:

[0032]

[0033] Further, in step C1, the amount ratio of methyldiethoxysilane, γ-chloropropylmethyldiethoxysilane, anhydrous ethanol and purified water is 5g:3g:12mL:6mL, and the post-treatment operation includes: after the reaction is completed, the temperature of the three-necked flask is increased to 65-75°C, and the solvent is evaporated under reduced pressure to obtain polysiloxane; in step C2, the amount ratio of polysiloxane, N,N-dimethylformamide, cyanuric acid, triethylamine and trimethylamine aqueous solution is 10g:35mL:1g:0.78g:10mL, and the mass dispersion of trimethylamine in the trimethylamine aqueous solution is 35%, and the post-treatment operation includes: after the reaction is completed, the temperature of the three-necked flask is increased to 65-75°C, and the solvent is evaporated under reduced pressure to obtain polysiloxane. The temperature of the three-necked flask is raised to 90-95° C., N,N-dimethylformamide is evaporated under reduced pressure, the temperature of the three-necked flask is lowered to room temperature, dichloromethane is added to the three-necked flask, stirred at room temperature for 20-25 min, filtered, the filter cake is washed three times with dichloromethane and then dried, the filter cake is transferred to a drying oven at a temperature of 60-70° C., and dried to constant weight to obtain a composite polysiloxane; in step C3, the amount ratio of the composite polysiloxane, isopropanol, propenol and catalyst is 10g:50mL:2g:0.02g, the catalyst is chloroplatinic acid, and the post-treatment operation includes: after the reaction is completed, the temperature of the three-necked flask is kept at reflux, and the solvent is evaporated to obtain a modified polysiloxane.

[0034] A method for preparing a high-toughness, flame-retardant nonwoven fabric comprises the following steps:

[0035] S1, alternately stacking the polyurethane spinning membrane and the composite polyester spinning membrane layer by layer to obtain a multilayer spinning membrane whose upper and lower surface layers are both polyurethane spinning membranes;

[0036] S2, adding the multilayer spinning membrane to a hot rolling mill, setting the hot rolling pressure to 3-5 MPa, using 0.5 mol / L hydrochloric acid as a water source, heating and evaporating to form hydrochloric acid vapor, subjecting the multilayer spinning membrane to steam permeation treatment for 35-45 minutes, cooling to room temperature, and discharging to obtain a composite non-woven fabric crude product;

[0037] S3. Washing the crude non-woven fabric with purified water and soap, drying it in the sun, and trimming the edges of the crude non-woven fabric to obtain a composite non-woven fabric.

[0038] The present invention has the following beneficial effects:

[0039] 1. The composite non-woven fabric of the present invention is obtained by alternately stacking polyurethane spinning membranes and composite polyester spinning membranes, and undergoing steam hot rolling treatment to promote the disconnection of siloxane bonds on the polyester spinning membranes and the recombinant cross-linking of active functional groups on the composite polyester spinning membranes or the polyurethane spinning membranes, thereby increasing the degree of cross-linking between the polyurethane spinning membranes and the polyurethane spinning membranes themselves or the composite polyester spinning membranes, thereby forming a stably cross-linked integrated non-woven fabric material, simplifying the preparation process of the non-woven fabric, and effectively increasing the tensile toughness of the non-woven fabric by increasing the degree of cross-linking of the multiple fiber layers constituting the non-woven fabric material. Both cyanuric acid and methylamine hydrochloride on the composite polyester spinning membranes have good flame retardant properties, and the flame retardant properties of the non-woven fabric are improved by their cooperation with the non-woven fabric with a high degree of cross-linking.

[0040] 2. The composite non-woven fabric of the present invention is prepared by condensing and cross-linking polyethylene glycol 400 and isophorone diisocyanate in a toluene system and then further reacting with hydroxyl-terminated polydimethylsiloxane as a chain extender to obtain a composite polyurethane having polydimethylsiloxane as a flexible block. The composite polyurethane reacts with 3-aminopropyltriethoxysilane to form a modified polyurethane modified by triethoxysilane end-capping. The modified polyurethane spinning solution is electrostatically spun using nitrogen as a gas flow to obtain a polyurethane spinning membrane modified with a large amount of triethoxysilane. The polyurethane itself contains ester bonds. Or ether bond, so that the material can be deformed during the stretching process and has a certain resilience, and the composite polyurethane contains polyethylene glycol 400 and polydimethylsiloxane segments at the same time. The polyethylene glycol 400 and polydimethylsiloxane cooperate with each other to improve the tensile toughness of the composite polyurethane spinning membrane. The siloxyethane end groups set at both ends of the modified polyurethane segment can be hydrolyzed under acidic conditions to form active silanol groups and react with active groups on the polyurethane spinning membrane or the composite polyester spinning membrane to form chemical crosslinking, thereby improving the crosslinking degree of the composite non-woven fabric and further improving the tensile toughness of the composite non-woven fabric.

[0041] 3. The composite nonwoven fabric of the present invention is prepared by condensing methyldiethoxysilane and γ-chloropropylmethyldiethoxysilane under acidic conditions to obtain a long straight-chain polysiloxane modified with halogen and silicon hydrogen. The halogen on the polysiloxane undergoes a nucleophilic substitution reaction with cyanuric acid and trimethylamine in sequence to form a new amino compound. Then, the polysiloxane undergoes a substitution addition reaction with allyl alcohol under the action of a catalyst to form an alcohol hydroxyl group on the polysiloxane. By modifying the polar alcohol hydroxyl group on the polysiloxane, a hydrogen bond interaction can be formed with the ester group on the polyethylene terephthalate, which helps to reduce the mutual repulsion between the two and improve the compatibility between the polysiloxane and the polyethylene terephthalate, thereby preparing a uniformly mixed spinning solution, which is prepared by electrospinning. The composite polyester spinning membrane in which polyethylene terephthalate and modified polysiloxane are uniformly mixed and distributed, the softness and elasticity of the siloxane segment may help to improve the toughness and tear strength of the membrane, when the polyurethane spinning membrane and the composite polyester spinning membrane are subjected to steam hot rolling treatment, hydrochloric acid vapor enters the multi-layer spinning membrane, promotes the cross-linking between the membrane layers, and improves the cross-linking degree between the membrane layers, the cyanuric acid and trimethylamine modified on the polysiloxane segment can be decomposed to produce gases such as water vapor and carbon dioxide when burned at high temperature, these gases will dilute the oxygen on the surface of the combustible, take away part of the heat, reduce the surface temperature of the combustible, and thus reduce the combustion rate, polysilane will be cracked at high temperature to produce siloxane, these compounds can further inhibit the spread of flames, at the same time, these compounds cooperate with cyanuric acid and trimethylamine to form a non-combustible protective layer on the surface of the combustible, inhibit the thermal decomposition and degradation of the polyester non-woven fabric during the combustion process, thereby reducing the generation of combustibles and reducing the combustion intensity, thereby achieving a flame retardant effect. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Example 1

[0044] This embodiment provides a method for preparing a high-toughness, flame-retardant non-woven fabric, comprising the following steps:

[0045] S1. Preparation of modified polyurethane

[0046] Weigh: 40 g of polyethylene glycol 400, 45 g of isophorone diisocyanate, and 400 mL of toluene, add them into a three-necked flask protected by nitrogen, stir, raise the temperature of the three-necked flask to 80° C., keep warm for 3 h, add 200 g of hydroxyl-terminated polydimethylsiloxane into the three-necked flask, continue to keep warm for 4 h, keep the three-necked flask at 80° C., and evaporate the solvent under reduced pressure to obtain a composite polyurethane, wherein the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 2000;

[0047] Weigh: 80 g of composite polyurethane and 480 mL of toluene are added into a three-necked flask and stirred evenly. The temperature of the three-necked flask is increased to 45°C. 3-aminopropyltriethoxysilane is slowly added into the three-necked flask. The residual isocyanate group is determined by the di-n-butylamine method until no is detected. The reaction is kept warm for 2 hours. The temperature of the three-necked flask is increased to 75°C. The solvent is evaporated under reduced pressure to obtain a modified polyurethane.

[0048] S2. Preparation of polyurethane spinning membrane

[0049] Weigh: 100 g of modified polyurethane and 400 mL of N,N-dimethylformamide, add them into a beaker and stir evenly to obtain a spinning solution, add the spinning solution into a syringe, and install the syringe on the injection pump of the electrospinning machine, set the propulsion speed to 0.001 mm / s, the spinning voltage to 24 kV, and collect the spinning membrane on a drum coated with aluminum foil. The distance between the drum and the electrospinning nozzle is 8 cm, the air flow velocity is 12 m / s, the nitrogen content in the air flow is higher than 95%, and electrospinning is performed to obtain a polyurethane spinning membrane.

[0050] S3. Preparation of modified polysiloxane

[0051] Weigh: 50 g of methyldiethoxysilane, 30 g of γ-chloropropylmethyldiethoxysilane, 120 mL of anhydrous ethanol and 60 mL of purified water, add them into a three-necked flask and stir evenly, add hydrochloric acid into the three-necked flask, adjust the pH of the system to 3, raise the temperature of the three-necked flask to 50° C., keep the temperature for 3 h, raise the temperature of the three-necked flask to 65° C., and evaporate the solvent under reduced pressure to obtain polysiloxane;

[0052] Weigh: 100 g of polysiloxane and 350 mL of N,N-dimethylformamide are added to a three-necked flask and stirred until the system is dissolved. 10 g of cyanuric acid and 7.8 g of triethylamine are added to the three-necked flask. The temperature of the three-necked flask is increased to 85° C., and the reaction is kept warm for 8 hours. The temperature of the three-necked flask is lowered to room temperature, and the filtrate is transferred to the three-necked flask and stirred. 100 mL of a 35 wt% trimethylamine aqueous solution is added to the three-necked flask. The temperature of the three-necked flask is increased to 55° C., and the reaction is stirred for 20 hours. The temperature of the three-necked flask is increased to 90° C., and N,N-dimethylformamide is evaporated under reduced pressure. The temperature of the three-necked flask is lowered to room temperature. Dichloromethane is added to the three-necked flask, and the mixture is stirred at room temperature for 20 minutes. The filter cake is washed three times with dichloromethane and then dried. The filter cake is transferred to a drying oven at a temperature of 60° C. and dried to constant weight to obtain a composite polysiloxane;

[0053] Weigh: 100 g of composite polysiloxane and 500 mL of isopropanol are added to a three-necked flask and stirred until the system is dissolved. 20 g of propenol and 0.2 g of chloroplatinic acid are added to the three-necked flask. The temperature of the three-necked flask is increased to reflux, and the reaction is kept warm for 6 hours. The temperature of the three-necked flask is kept at reflux, and the solvent is evaporated to obtain modified polysiloxane.

[0054] S4. Preparation of composite polyester spinning membrane

[0055] Weigh: 50 g of polyethylene terephthalate, 30 g of modified polysiloxane, and 300 mL of hexafluoroisopropanol, add into a beaker, stir until the system is completely dissolved, and stand to defoam to obtain a spinning solution;

[0056] The electrospinning operation includes: adding the spinning solution into the syringe of the electrospinning machine, and installing the syringe on the injection pump of the electrospinning machine, setting the propulsion speed to 0.001 mm / s, the spinning voltage to 23 kV, and collecting the spun membrane on a drum with an aluminum foil coated surface. The distance between the drum and the electrospinning nozzle is 15 cm, and the air flow velocity is 8 m / s.

[0057] S5. Preparation of composite nonwoven fabric

[0058] The polyurethane spinning membrane and the composite polyester spinning membrane are alternately stacked layer by layer to obtain a multilayer spinning membrane whose upper and lower surface layers are both polyurethane spinning membranes, wherein the stacking number of the multilayer spinning membrane is 5 layers;

[0059] The multilayer spinning membrane was added into a hot rolling mill, the hot rolling pressure was set to 3MPa, 0.5mol / L hydrochloric acid was used as a water source, hydrochloric acid vapor was formed by heating and evaporation, the multilayer spinning membrane was subjected to steam permeation treatment for 35min, the temperature was lowered to room temperature, and the composite non-woven fabric crude product was obtained by discharging;

[0060] The crude nonwoven fabric is washed with purified water and soap, and then aired to dry. The edges of the crude nonwoven fabric are trimmed to obtain a composite nonwoven fabric.

[0061] Example 2

[0062] This embodiment provides a method for preparing a high-toughness, flame-retardant non-woven fabric, comprising the following steps:

[0063] S1. Preparation of modified polyurethane

[0064] Weigh: 40 g of polyethylene glycol 400, 45 g of isophorone diisocyanate, and 400 mL of toluene, add them into a three-necked flask protected by nitrogen, stir, raise the temperature of the three-necked flask to 85° C., and keep the temperature for reaction for 3.5 hours, add 200 g of hydroxyl-terminated polydimethylsiloxane into the three-necked flask, continue to keep the temperature for reaction for 5 hours, keep the temperature of the three-necked flask at 85° C., and evaporate the solvent under reduced pressure to obtain a composite polyurethane, wherein the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 2000;

[0065] Weigh: 80 g of composite polyurethane and 480 mL of toluene are added into a three-necked flask and stirred evenly. The temperature of the three-necked flask is increased to 47°C. 3-aminopropyltriethoxysilane is slowly added into the three-necked flask. The residual isocyanate group is determined by the di-n-butylamine method until no is detected. The reaction is kept warm for 2.5 hours. The temperature of the three-necked flask is increased to 80°C. The solvent is evaporated under reduced pressure to obtain a modified polyurethane.

[0066] S2. Preparation of polyurethane spinning membrane

[0067] Weigh: 100 g of modified polyurethane and 400 mL of N,N-dimethylformamide, add them into a beaker and stir evenly to obtain a spinning solution, add the spinning solution into a syringe, and install the syringe on the injection pump of the electrospinning machine, set the propulsion speed to 0.001 mm / s, the spinning voltage to 24 kV, and collect the spinning membrane on a drum coated with aluminum foil. The distance between the drum and the electrospinning nozzle is 8 cm, the air flow velocity is 12 m / s, the nitrogen content in the air flow is higher than 95%, and electrospinning is performed to obtain a polyurethane spinning membrane.

[0068] S3. Preparation of modified polysiloxane

[0069] Weigh: 50 g of methyldiethoxysilane, 30 g of γ-chloropropylmethyldiethoxysilane, 120 mL of anhydrous ethanol and 60 mL of purified water, add them into a three-necked flask and stir evenly, add hydrochloric acid into the three-necked flask, adjust the pH of the system to 3, raise the temperature of the three-necked flask to 55° C., keep the temperature for 4 h, raise the temperature of the three-necked flask to 70° C., and evaporate the solvent under reduced pressure to obtain polysiloxane;

[0070] Weigh: 100 g of polysiloxane and 350 mL of N,N-dimethylformamide are added to a three-necked flask and stirred until the system is dissolved. 10 g of cyanuric acid and 7.8 g of triethylamine are added to the three-necked flask. The temperature of the three-necked flask is increased to 90° C., and the reaction is kept warm for 9 hours. The temperature of the three-necked flask is lowered to room temperature, and the filtrate is transferred to the three-necked flask and stirred. 100 mL of a 35 wt% trimethylamine aqueous solution is added to the three-necked flask. The temperature of the three-necked flask is increased to 60° C., and the reaction is stirred for 21 hours. The temperature of the three-necked flask is increased to 93° C., and N,N-dimethylformamide is evaporated under reduced pressure. The temperature of the three-necked flask is lowered to room temperature. Dichloromethane is added to the three-necked flask, and the mixture is stirred at room temperature for 24 minutes. The filter cake is washed three times with dichloromethane and then dried. The filter cake is transferred to a drying oven at a temperature of 65° C. and dried to constant weight to obtain a composite polysiloxane;

[0071] Weigh: 100 g of composite polysiloxane and 500 mL of isopropanol are added to a three-necked flask and stirred until the system is dissolved. 20 g of propenol and 0.2 g of chloroplatinic acid are added to the three-necked flask. The temperature of the three-necked flask is increased to reflux, and the reaction is kept warm for 7 hours. The temperature of the three-necked flask is kept at reflux, and the solvent is evaporated to obtain modified polysiloxane.

[0072] S4. Preparation of composite polyester spinning membrane

[0073] Weigh: 50 g of polyethylene terephthalate, 30 g of modified polysiloxane, and 300 mL of hexafluoroisopropanol, add into a beaker, stir until the system is completely dissolved, and stand to defoam to obtain a spinning solution;

[0074] The electrospinning operation includes: adding the spinning solution into the syringe of the electrospinning machine, and installing the syringe on the injection pump of the electrospinning machine, setting the propulsion speed to 0.001 mm / s, the spinning voltage to 23 kV, and collecting the spun membrane on a drum with an aluminum foil coated surface. The distance between the drum and the electrospinning nozzle is 15 cm, and the air flow velocity is 8 m / s.

[0075] S5. Preparation of composite nonwoven fabric

[0076] The polyurethane spinning membrane and the composite polyester spinning membrane are alternately stacked layer by layer to obtain a multilayer spinning membrane whose upper and lower surface layers are both polyurethane spinning membranes, wherein the stacking number of the multilayer spinning membrane is 7 layers;

[0077] The multilayer spinning membrane was added into a hot rolling mill, the hot rolling pressure was set to 4 MPa, 0.5 mol / L hydrochloric acid was used as a water source, hydrochloric acid vapor was formed by heating and evaporation, the multilayer spinning membrane was subjected to steam permeation treatment for 40 minutes, the temperature was lowered to room temperature, and the composite non-woven fabric crude product was obtained by discharging;

[0078] The crude nonwoven fabric is washed with purified water and soap, and then aired to dry. The edges of the crude nonwoven fabric are trimmed to obtain a composite nonwoven fabric.

[0079] Example 3

[0080] This embodiment provides a method for preparing a high-toughness, flame-retardant non-woven fabric, comprising the following steps:

[0081] S1. Preparation of modified polyurethane

[0082] Weigh: 40 g of polyethylene glycol 400, 45 g of isophorone diisocyanate, and 400 mL of toluene, add them into a three-necked flask protected by nitrogen, stir, raise the temperature of the three-necked flask to 90° C., keep warm for 4 hours, add 200 g of hydroxyl-terminated polydimethylsiloxane into the three-necked flask, continue to keep warm for 6 hours, keep the three-necked flask at 90° C., and evaporate the solvent under reduced pressure to obtain a composite polyurethane, wherein the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 2000;

[0083] Weigh: 80 g of composite polyurethane and 480 mL of toluene are added into a three-necked flask and stirred evenly. The temperature of the three-necked flask is increased to 50°C. 3-aminopropyltriethoxysilane is slowly added into the three-necked flask. The residual isocyanate group is determined by the di-n-butylamine method until no is detected. The reaction is kept warm for 3 hours. The temperature of the three-necked flask is increased to 85°C. The solvent is evaporated under reduced pressure to obtain a modified polyurethane.

[0084] S2. Preparation of polyurethane spinning membrane

[0085] Weigh: 100 g of modified polyurethane and 400 mL of N,N-dimethylformamide, add them into a beaker and stir evenly to obtain a spinning solution, add the spinning solution into a syringe, and install the syringe on the injection pump of the electrospinning machine, set the propulsion speed to 0.001 mm / s, the spinning voltage to 24 kV, and collect the spinning membrane on a drum coated with aluminum foil. The distance between the drum and the electrospinning nozzle is 8 cm, the air flow velocity is 12 m / s, the nitrogen content in the air flow is higher than 95%, and electrospinning is performed to obtain a polyurethane spinning membrane.

[0086] S3. Preparation of modified polysiloxane

[0087] Weigh: 50 g of methyldiethoxysilane, 30 g of γ-chloropropylmethyldiethoxysilane, 120 mL of anhydrous ethanol and 60 mL of purified water into a three-necked flask and stir evenly, add hydrochloric acid into the three-necked flask to adjust the pH of the system to 3, raise the temperature of the three-necked flask to 60° C., keep the reaction warm for 5 h, raise the temperature of the three-necked flask to 75° C., and evaporate the solvent under reduced pressure to obtain polysiloxane;

[0088] Weigh: 100 g of polysiloxane and 350 mL of N,N-dimethylformamide are added to a three-necked flask and stirred until the system is dissolved. 10 g of cyanuric acid and 7.8 g of triethylamine are added to the three-necked flask. The temperature of the three-necked flask is increased to 95° C., and the reaction is kept warm for 10 hours. The temperature of the three-necked flask is lowered to room temperature, and the filtrate is transferred to the three-necked flask and stirred. 100 mL of a 35 wt% trimethylamine aqueous solution is added to the three-necked flask. The temperature of the three-necked flask is increased to 65° C., and the reaction is stirred for 22 hours. The temperature of the three-necked flask is increased to 95° C., and N,N-dimethylformamide is evaporated under reduced pressure. The temperature of the three-necked flask is lowered to room temperature. Dichloromethane is added to the three-necked flask, and the mixture is stirred at room temperature for 25 minutes. The filter cake is washed three times with dichloromethane and then dried. The filter cake is transferred to a drying oven at a temperature of 70° C. and dried to constant weight to obtain a composite polysiloxane;

[0089] Weigh: 100 g of composite polysiloxane and 500 mL of isopropanol are added to a three-necked flask and stirred until the system is dissolved. 20 g of propenol and 0.2 g of chloroplatinic acid are added to the three-necked flask. The temperature of the three-necked flask is increased to reflux, and the reaction is kept warm for 8 hours. The temperature of the three-necked flask is kept at reflux, and the solvent is evaporated to obtain modified polysiloxane.

[0090] S4. Preparation of composite polyester spinning membrane

[0091] Weigh: 50 g of polyethylene terephthalate, 30 g of modified polysiloxane, and 300 mL of hexafluoroisopropanol, add into a beaker, stir until the system is completely dissolved, and stand to defoam to obtain a spinning solution;

[0092] The electrospinning operation includes: adding the spinning solution into the syringe of the electrospinning machine, and installing the syringe on the injection pump of the electrospinning machine, setting the propulsion speed to 0.001 mm / s, the spinning voltage to 23 kV, and collecting the spun membrane on a drum with an aluminum foil coated surface. The distance between the drum and the electrospinning nozzle is 15 cm, and the air flow velocity is 8 m / s.

[0093] S5. Preparation of composite nonwoven fabric

[0094] The polyurethane spinning membrane and the composite polyester spinning membrane are alternately stacked layer by layer to obtain a multilayer spinning membrane whose upper and lower surface layers are both polyurethane spinning membranes, wherein the stacking number of the multilayer spinning membrane is 7 layers;

[0095] The multilayer spinning membrane was added to a hot rolling mill, the hot rolling pressure was set to 5 MPa, 0.5 mol / L hydrochloric acid was used as a water source, hydrochloric acid vapor was formed by heating and evaporation, the multilayer spinning membrane was subjected to steam permeation treatment for 45 minutes, the temperature was lowered to room temperature, and the composite non-woven fabric crude product was obtained by discharging;

[0096] The crude nonwoven fabric is washed with purified water and soap, and then aired to dry. The edges of the crude nonwoven fabric are trimmed to obtain a composite nonwoven fabric.

[0097] Comparative Example 1

[0098] The difference between this comparative example and Example 3 is that the modified polyurethane in step S2 is replaced by an equal amount of the composite polyurethane in step S1.

[0099] Comparative Example 2

[0100] The difference between this comparative example and Example 3 is that the modified polysiloxane in step S4 is replaced by an equal amount of the polysiloxane in step S3.

[0101] Comparative Example 3

[0102] The difference between this comparative example and Example 3 is that the modified polysiloxane in step S4 is replaced by an equal amount of the composite polysiloxane in step S3.

[0103] Performance Testing:

[0104] The toughness and combustion performance of the composite non-woven fabrics prepared in Examples 1-3 and Comparative Examples 1-3 were tested, wherein the toughness was measured according to the standard GB / T 24218.3-2010 "Test methods for textile nonwovens Part 3: Determination of breaking strength and elongation at break (strip method)" and the standard GB / T 24218.102-2022 "Test methods for textile nonwovens Part 102: Determination of tensile elasticity" to measure the breaking strength, elongation at break, elastic recovery at constant elongation and stress relaxation at constant elongation of the specimens; the combustion performance was measured according to the standard GB / T 33101-2016 "Flame retardant dipped canvas combustion test method" to measure the flaming combustion time, flameless combustion time and burning damage length of the specimens. The specific test results are shown in the following table:

[0105]

[0106] Data Analysis:

[0107] By comparing and analyzing the data in the above table, the composite non-woven fabric prepared by the present invention has a breaking strength of 53.6 MPa, an elongation at break of 76.6%, an elastic recovery rate at a fixed elongation of 91.2%, a stress relaxation rate at a fixed elongation of 9.7%, a flaming combustion time of 1.5 s, a flameless combustion time of 0.2 s, and a burning damage length of 4.4 mm. All the test data are better than those of the comparative example, indicating that the present invention synthesizes a composite polyurethane having polyethylene glycol and polysiloxane segments, and then modifies the composite polyurethane fiber membrane to prepare the polyurethane fiber membrane, which is then stacked layer by layer with a composite polyester spinning membrane composed of modified polysiloxane and polyethylene terephthalate, which not only effectively improves the breaking strength and tensile properties of the composite non-woven fabric, but also improves the flame retardant properties of the composite non-woven fabric.

[0108] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0109] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0110] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-tenacity, flame-retardant nonwoven fabric, characterized in that: The polyurethane spinning membrane and the composite polyester spinning membrane are alternately stacked layer by layer to obtain a multilayer spinning membrane whose upper and lower surface layers are both polyurethane spinning membranes, and then the multilayer spinning membrane is subjected to steam hot rolling treatment to obtain; The polyurethane spinning membrane is obtained by processing the following steps: A1. Add polyethylene glycol, isophorone diisocyanate and toluene into a three-necked flask protected by nitrogen and stir. Raise the temperature of the three-necked flask to 80-90° C. and keep warm for 3-4 hours. Add hydroxyl-terminated polydimethylsiloxane into the three-necked flask and continue to keep warm for 4-6 hours. Post-treat to obtain composite polyurethane. A2. Add composite polyurethane and toluene into a three-necked flask and stir evenly. Raise the temperature of the three-necked flask to 45-50° C., slowly add 3-aminopropyltriethoxysilane into the three-necked flask, and determine the residual isocyanate group by di-n-butylamine method until no isocyanate group is detected. Keep the temperature for reaction for 2-3 hours, and perform post-treatment to obtain modified polyurethane. A3, adding modified polyurethane and N,N-dimethylformamide into a beaker and stirring evenly to obtain a spinning solution, and electrospinning the spinning solution to obtain a polyurethane spinning membrane; The composite polyester spinning membrane is obtained by processing the following steps: B1. Add polyethylene terephthalate, modified polysiloxane and hexafluoroisopropanol into a beaker, stir until the system is completely dissolved, and stand to defoam to obtain a spinning solution; B2, transferring the spinning solution to an electrospinning machine for electrospinning to obtain a composite polyester spinning membrane; The modified polysiloxane is processed by the following steps: C1. Add methyldiethoxysilane, γ-chloropropylmethyldiethoxysilane, anhydrous ethanol and purified water into a three-necked flask and stir evenly. Add hydrochloric acid into the three-necked flask to adjust the pH value of the system to 3. Raise the temperature of the three-necked flask to 50-60° C., keep the temperature for reaction for 3-5 hours, and perform post-treatment to obtain polysiloxane. C2, adding polysiloxane and N,N-dimethylformamide to a three-necked flask and stirring until the system is dissolved, adding cyanuric acid and triethylamine to the three-necked flask, raising the temperature of the three-necked flask to 85-95°C, keeping the temperature for reaction for 8-10 hours, lowering the temperature of the three-necked flask to room temperature, filtering with suction, transferring the filtrate to a three-necked flask and stirring, adding trimethylamine aqueous solution to the three-necked flask, raising the temperature of the three-necked flask to 55-65°C, stirring for reaction for 20-22 hours, and post-treating to obtain composite polysiloxane; C3. Add the composite polysiloxane and isopropanol into a three-necked flask and stir until the system is dissolved. Add propylene alcohol and a catalyst into the three-necked flask. Increase the temperature of the three-necked flask to reflux the system. Keep the temperature to react for 6-8 hours. Post-treat to obtain the modified polysiloxane.

2. A high-tenacity, flame-retardant nonwoven fabric according to claim 1, characterized in that: The stacking number of the multi-layer spinning membrane is 5 or 7 layers.

3. The high-tenacity, flame-retardant nonwoven fabric according to claim 1, characterized in that: In step A1, the amount ratio of polyethylene glycol, isophorone diisocyanate, toluene, and hydroxyl-terminated polydimethylsiloxane is 4g:4.5g:40mL:20g, the polyethylene glycol is polyethylene glycol 400, and the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 2000. The post-processing operation includes: after the reaction is completed, the three-necked flask is kept warm at 80-90°C, and the solvent is evaporated under reduced pressure to obtain a composite polyurethane; in step A2, the amount ratio of the composite polyurethane and toluene is 1g:6mL, and the post-processing operation includes: after the reaction is completed, the temperature of the three-necked flask is increased to 75-85°C, and the solvent is evaporated under reduced pressure to obtain a modified polyurethane.

4. The high-tenacity, flame-retardant nonwoven fabric according to claim 1, characterized in that: In step A3, the amount ratio of modified polyurethane and N,N-dimethylformamide is 1g:4mL, and the electrospinning operation includes: the electrospinning operation includes: adding the spinning solution into the syringe, and installing the syringe on the injection pump of the electrospinning machine, setting the propulsion speed to 0.001mm / s, the spinning voltage to 24kV, and the spinning membrane is collected on a drum coated with aluminum foil on the surface. The distance between the drum and the electrospinning nozzle is 8cm, the air flow velocity is 12m / s, and the nitrogen content in the air flow is higher than 95%.

5. The high-tenacity, flame-retardant nonwoven fabric according to claim 1, characterized in that: In step B1, the dosage ratio of polyethylene terephthalate, modified polysiloxane and hexafluoroisopropanol is 5g:3g:30mL; in step B2, the electrospinning operation includes: adding the spinning solution into the syringe, and installing the syringe on the injection pump of the electrospinning machine, setting the propulsion speed to 0.001mm / s, the spinning voltage to 23kV, and collecting the spinning membrane on a drum coated with aluminum foil on the surface. The distance between the drum and the electrospinning nozzle is 15cm, and the air flow velocity is 8m / s.

6. The high-tenacity, flame-retardant nonwoven fabric according to claim 1, characterized in that: In step C1, the amount ratio of methyldiethoxysilane, γ-chloropropylmethyldiethoxysilane, anhydrous ethanol and purified water is 5g:3g:12mL:6mL, and the post-treatment operation includes: after the reaction is completed, the temperature of the three-necked flask is increased to 65-75°C, and the solvent is evaporated under reduced pressure to obtain polysiloxane; in step C2, the amount ratio of polysiloxane, N,N-dimethylformamide, cyanuric acid, triethylamine and trimethylamine aqueous solution is 10g:35mL:1g:0.78g:10mL, and the mass dispersion of trimethylamine in the trimethylamine aqueous solution is 35%, and the post-treatment operation includes: after the reaction is completed, the temperature of the three-necked flask is increased to 90-95° C., N,N-dimethylformamide is evaporated under reduced pressure, the temperature of the three-necked flask is lowered to room temperature, dichloromethane is added to the three-necked flask, stirred at room temperature for 20-25 minutes, filtered, the filter cake is washed three times with dichloromethane and then dried, the filter cake is transferred to a drying oven at a temperature of 60-70° C., and dried to constant weight to obtain a composite polysiloxane; in step C3, the amount ratio of the composite polysiloxane, isopropanol, propenol and catalyst is 10g:50mL:2g:0.02g, the catalyst is chloroplatinic acid, and the post-treatment operation includes: after the reaction is completed, the temperature of the three-necked flask is kept at reflux, and the solvent is evaporated to obtain a modified polysiloxane.

7. A method for preparing a high-tenacity, flame-retardant nonwoven fabric according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, alternately stacking the polyurethane spinning membrane and the composite polyester spinning membrane layer by layer to obtain a multilayer spinning membrane whose upper and lower surface layers are both polyurethane spinning membranes; S2, adding the multilayer spinning membrane to a hot rolling mill, setting the hot rolling pressure to 3-5 MPa, using 0.5 mol / L hydrochloric acid as a water source, heating and evaporating to form hydrochloric acid vapor, subjecting the multilayer spinning membrane to steam permeation treatment for 35-45 minutes, cooling to room temperature, and discharging to obtain a composite non-woven fabric crude product; S3. Washing the crude non-woven fabric with purified water and soap, drying it in the sun, and trimming the edges of the crude non-woven fabric to obtain a composite non-woven fabric.

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