A high flame retardant protective composite fabric and preparation method thereof

Abstract

The present invention belongs to the technical field of fabrics, and in particular relates to a highly flame-retardant protective composite fabric and a preparation method thereof. A modified polyimide / polyether composite aerogel is used as a heat insulation layer, and an aramid fiber felt is used as a substrate; a modified polyimide / polyether composite aerogel is generated by polymerization reaction using 4,4'-diaminodiphenyl ether, modified polyetheramine D-2000 and 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride as raw materials. Since the aerogel is a porous ultra-light material, it has the characteristics of low density and high efficiency heat insulation. At the same time, since a phosphorous acid group is introduced during the modification process, it can decompose at high temperature to produce a flame retardant gas, so the prepared fabric has good flame retardant properties.

Description

Technical Field

[0001] The invention relates to the technical field of fabrics, and in particular to a highly flame-retardant protective composite fabric and a preparation method thereof. Background Art

[0002] As a kind of protective workwear, thermal protective clothing can prevent people from suffering from thermal damage in high-temperature environments. It is widely used in industries full of potential thermal hazards, such as firefighting, military, industry, hydropower, and nuclear power. In a complex thermal environment, there are one or more heat sources such as thermal radiation, thermal convection, high-temperature steam, flame burning, molten metal and chemical splashing, which can cause serious thermal damage to the human body. Therefore, thermal protective workwear needs an efficient insulation layer that can prevent heat transfer, slow down the temperature rise rate of the human skin, and increase the safe rescue and action time of personnel in the fire scene.

[0003] The patent with application number CN202310890517.1 discloses a flame-retardant fabric and a preparation method thereof, including a flame-retardant compound, graphene oxide, polypropylene and cotton fiber. The prepared flame-retardant compound can be mixed with graphene oxide to modify the molten polypropylene to obtain modified polypropylene. The flame-retardant fabric prepared together with the cotton fiber is not only soft and breathable, but also has excellent flame retardant effect; the patent with application number CN202311543164.4 discloses a flame-retardant composite fabric and a preparation process thereof, which is formed by bonding an inner fabric and an outer fabric. By subjecting pentaerythritol tetrakis(3-mercaptopropionic acid) ester and triallyl cyanurate to a thiol-ene click reaction and adding triisopropylphenyl phosphate, a photocurable flame-retardant coating containing three flame retardant elements of N, P and S can be prepared, thereby improving the double bond conversion rate and flame retardant effect of the coating.

[0004] However, the protective workwear that has been developed and applied so far is relatively heavy, so researching a lightweight and efficient functional thermal insulation material has become a research hotspot. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a highly flame-retardant protective composite fabric and a preparation method thereof, which uses aramid fiber felt as a base material and is composited with modified polyimide / polyether aerogel to obtain a protective fabric with good flame retardant effect.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0007] A highly flame-retardant protective composite fabric, comprising a heat-insulating layer and a substrate; the heat-insulating layer is a modified polyimide / polyether composite aerogel, and the substrate is an aramid fiber felt;

[0008] The preparation method of the modified polyimide / polyether composite aerogel is as follows: under an inert atmosphere, 4,4'-diaminodiphenyl ether and modified polyether amine D-2000 are dissolved in methyl pyrrolidone, 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride and pyridine are added thereto, reacting at 75-85°C for 2-4h, adding toluene, heating to 165-185°C and reacting for 4-6h, cooling to room temperature after the reaction is completed, precipitating into isopropanol, filtering and dissolving in a saturated chloroform solution, pouring into a mold for molding, freeze-drying and demoulding, heating three times and then cooling to room temperature to obtain the modified polyimide / polyether composite aerogel. The mass ratio of 3,4,3',4'-diphenyl ether tetracarboxylic acid dianhydride, 4,4'-diaminodiphenyl ether and modified polyetheramine D-2000 is 12-15:11-14:1, the volume ratio of methyl pyrrolidone, pyridine and toluene is 50-60:1:45-55, and the amount of 4,4'-diaminodiphenyl ether in the system is 12-18 g / mL; the three-time heating process after freeze-drying demoulding is: heating at 2-4 ° C / min The temperature is increased to 100°C at a rate of 2°C / min and kept for 1-3h, then increased to 200°C at a rate of 3-5°C / min and kept for 1-3h, and finally increased to 300°C at a rate of 2-4°C / min and kept for 1-3h; preferably, the temperature is increased to 100°C at a rate of 2°C / min and kept for 1h, then increased to 200°C at a rate of 5°C / min and kept for 1h, and finally increased to 300°C at a rate of 2°C / min and kept for 1h.

[0009] Furthermore, the preparation method of the modified polyetheramine D-2000 is:

[0010] S1. In an inert atmosphere, add polyetheramine D-2000, hydroxyethyl acrylate and xylene to a reactor, raise the temperature to 60-70°C, stir for 1-2h, then raise the temperature to 100-110°C, add initiator and crosslinking agent, continue the reaction for 2-4h, cool to room temperature, filter, wash and dry to obtain intermediate I; wherein the inert atmosphere is nitrogen or argon, preferably nitrogen; the initiator is one or a mixture of cyclohexanone peroxide, dibenzoyl peroxide and tert-butyl hydroperoxide; the crosslinking agent is triallyl isocyanurate; wherein the mass ratio of polyetheramine D-2000, hydroxyethyl acrylate, xylene, initiator and crosslinking agent is 1:2-3:10-12:0.2-0.5:0.05-0.08; the amount of initiator in the system is 0.5-1.2 g / mL;

[0011] S2. Add the intermediate I obtained in step S1, triethylamine and anhydrous xylene into the reactor, add diethylphosphite chloride dropwise under ice bath condition, continue the reaction for 2-4h after the addition is completed, remove the anhydrous xylene after the reaction is completed, add water and dichloromethane for extraction, collect the organic phase, and dry it to obtain modified polyetheramine D-2000; wherein the mass ratio of intermediate I, triethylamine, diethylphosphite chloride and anhydrous xylene is 3-6:1:2-5:10-15; the amount of intermediate I in the system is 10-15g / mL.

[0012] The present invention also provides a method for preparing a highly flame-retardant protective composite fabric, the preparation process of which is as follows: the thermal insulation layer and the substrate are laminated to obtain the composite fabric, the composite fabric is passed through the wave head of an ultrasonic sewing machine to make the fabric surface vibrate on a pattern roller to form a fabric surface with uniform pressure points, and the highly flame-retardant protective composite fabric is obtained; wherein the adhesive used in the lamination bonding is polyurethane, and the amount of adhesive applied is 15-20g / m 2 The hot pressing temperature is 240-250°C, the hot pressing time is 10-15s, and the hot pressing pressure is 3-4kgf / cm; preferably, the glue amount is 18g / m 2 The hot pressing temperature is 245°C, the hot pressing time is 12s, and the hot pressing pressure is 4kgf / cm2; the weight of the substrate is 160-180g / m 2 , thickness is 0.5-0.8mm, weight of thermal insulation layer is 160-180g / m 2 , thickness is 0.5-0.8mm.

[0013] The present invention has the following beneficial effects:

[0014] In the present invention, 4,4'-diaminodiphenyl ether, 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride and modified polyetheramine D-2000 are used for reaction to prepare a modified polyimide / polyether composite aerogel in which flexible chain molecules and rigid chain molecules are connected by covalent bonds, which has the advantages of high mechanical strength and excellent thermal stability of polyimide and low density and high-efficiency thermal insulation of aerogel; in particular, a phosphorous acid group is introduced into the side chain during the modification process, which can generate PO· free radicals during combustion, capture the free radicals generated by combustion, delay the combustion chain reaction, and decompose and promote the polymer to form a barrier layer, inhibit the generation and spread of flames, decompose at high temperature to generate flame-retardant gas, dilute the concentration of combustible gas, and delay the spread of flames, so that the prepared fabric has good flame retardant properties. DETAILED DESCRIPTION

[0015] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0016] 4,4'-diaminodiphenyl ether, 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride, hydroxyethyl acrylate, diethylphosphite chloride and polyetheramine D-2000 (average Mn ~ 2,000) were purchased from the official website of Aladdin Reagent. The aramid fiber felt used in the invention is aramid 1313 fiber felt purchased from Shandong Aobo Environmental Protection Technology Co., Ltd. The reagents used in the present invention are all commonly available on the market.

[0017] Example 1

[0018] A highly flame-retardant protective composite fabric comprises a heat-insulating layer and a substrate; the heat-insulating layer is a modified polyimide / polyether composite aerogel, and the substrate is an aramid fiber felt.

[0019] The preparation method of the modified polyimide / polyether composite aerogel is as follows: under a nitrogen atmosphere, 4,4'-diaminodiphenyl ether and modified polyether amine D-2000 are dissolved in methyl pyrrolidone, and then 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride and pyridine are added thereto, and the reaction is carried out at 80°C for 3 hours, and then toluene is added, and the temperature is raised to 170°C for reaction for 5 hours. After the reaction is completed, the mixture is cooled to room temperature and precipitated into isopropanol, and then the mixture is dissolved in a saturated chloroform solution after filtration, and then poured into a mold for molding, and then the mixture is demolded after freeze drying, and then cooled to room temperature after three heatings to obtain the modified polyimide / polyether composite aerogel; wherein, 3,4,3',4'-diaminodiphenyl ether and modified polyether amine D-2000 are dissolved in methyl pyrrolidone, and then the mixture is added thereto, and then the mixture is reacted at 80°C for 3 hours, and then the mixture is reacted at 170°C for 5 hours. The mass ratio of 4,3',4'-diphenyl ether tetracarboxylic dianhydride, 4,4'-diaminodiphenyl ether and modified polyetheramine D-2000 is 13:12:1, the volume ratio of methyl pyrrolidone, pyridine and toluene is 55:1:50, and the amount of 4,4'-diaminodiphenyl ether in the system is 15 g / mL; wherein, the process of heating three times after freeze-drying and demolding is as follows: heating to 100°C at a heating rate of 2°C / min and keeping warm for 1 hour, then heating to 200°C at a heating rate of 5°C / min and keeping warm for 1 hour, and finally heating to 300°C at a heating rate of 2°C / min and keeping warm for 1 hour.

[0020] Wherein, the preparation method of modified polyetheramine D-2000 is:

[0021] S1. In a nitrogen atmosphere, polyetheramine D-2000, hydroxyethyl acrylate and xylene were added to a reactor, the temperature was raised to 65°C, stirred for 2 hours, and then the temperature was raised to 105°C, and initiator dibenzoyl peroxide and auxiliary crosslinking agent triallyl isocyanurate were added thereto. After continuing the reaction for 3 hours, the mixture was cooled to room temperature, filtered, washed and dried to obtain intermediate I; wherein the mass ratio of polyetheramine D-2000, hydroxyethyl acrylate, xylene, initiator and auxiliary crosslinking agent was 1:2:10:0.3:0.06; the amount of initiator used in the system was 0.8 g / mL;

[0022] S2. Add the intermediate I obtained in step S1, triethylamine and anhydrous xylene into the reactor, add diethylphosphite chloride dropwise under ice bath condition, continue the reaction for 4 hours after the addition is completed, remove the anhydrous xylene after the reaction is completed, add water and dichloromethane for extraction, collect the organic phase, and dry it to obtain modified polyetheramine D-2000; wherein the mass ratio of intermediate I, triethylamine, diethylphosphite chloride and anhydrous xylene is 4:1:3:12, and the amount of intermediate I in the system is 12 g / mL.

[0023] A method for preparing a highly flame-retardant protective composite fabric, the preparation process comprising: laminating and bonding a heat insulating layer and a substrate to obtain a composite fabric, passing the composite fabric through the wave head of an ultrasonic sewing machine to make the fabric surface vibrate on a pattern roller to form a fabric surface with uniform pressure points, wherein the adhesive used in laminating and bonding is polyurethane, and the amount of adhesive applied is 18g / m 2 The hot pressing temperature is 245℃, the hot pressing time is 12s, the hot pressing pressure is 4kgf / cm2, and the weight of the substrate is 170g / m 2 , thickness is 0.6mm, weight of thermal insulation layer is 170g / m 2 , thickness is 0.6mm.

[0024] Example 2

[0025] Compared with Example 1, this embodiment has the following differences, specifically:

[0026] In the preparation process of modified polyimide / polyether composite aerogel: after adding 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride and pyridine and reacting at 75°C for 2h, toluene is added and the temperature is raised to 165°C for reaction for 4h; wherein, the mass ratio of 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride, 4,4'-diaminodiphenyl ether and modified polyetheramine D-2000 is 12:11:1, the volume ratio of methyl pyrrolidone, pyridine and toluene is 50:1:45, and the amount of 4,4'-diaminodiphenyl ether in the system is 12g / mL; wherein, the process of heating three times after freeze-drying and demolding is: heating to 100°C at a heating rate of 2°C / min and keeping warm for 3h, then heating to 200°C at a heating rate of 3°C / min and keeping warm for 3h, and finally heating to 300°C at a heating rate of 2°C / min and keeping warm for 3h.

[0027] In the preparation process of modified polyetheramine D-2000: in step S1, after adding polyetheramine D-2000, hydroxyethyl acrylate and xylene into the reactor, the temperature is increased to 60°C, stirred for 2 hours, and then the temperature is increased to 110°C, and an initiator and a cross-linking agent are added thereto to continue the reaction for 2 hours; wherein the mass ratio of polyetheramine D-2000, hydroxyethyl acrylate, xylene, initiator and cross-linking agent is 1:2:10:0.2:0.05; the amount of the initiator in the system is 0.5 g / mL; in step S2, after diethylphosphite chloride is added dropwise, the reaction is continued for 2 hours; wherein the mass ratio of intermediate I, triethylamine, diethylphosphite chloride and anhydrous xylene is 3:1:2:10, and the amount of intermediate I in the system is 10 g / mL.

[0028] In the preparation process of a highly flame retardant protective composite fabric, the glue amount during lamination is 15g / m 2 The hot pressing temperature is 240℃, the hot pressing time is 10s, the hot pressing pressure is 3kgf / cm2, and the weight of the substrate is 160g / m 2 , thickness is 0.5mm, weight of thermal insulation layer is 160g / m 2 , thickness is 0.5mm.

[0029] Example 3

[0030] Compared with Example 1, this embodiment has the following differences, specifically:

[0031] In the preparation process of modified polyimide / polyether composite aerogel: after adding 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride and pyridine and reacting at 85°C for 4 hours, toluene is added and the temperature is raised to 185°C for reaction for 6 hours; wherein, the mass ratio of 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride, 4,4'-diaminodiphenyl ether and modified polyetheramine D-2000 is 15:14:1, the volume ratio of methyl pyrrolidone, pyridine and toluene is 60:1:55, and the amount of 4,4'-diaminodiphenyl ether in the system is 18 g / mL; wherein, the process of heating three times after freeze-drying and demolding is: heating to 100°C at a heating rate of 4°C / min and keeping warm for 1 hour, then heating to 200°C at a heating rate of 5°C / min and keeping warm for 1 hour, and finally heating to 300°C at a heating rate of 4°C / min and keeping warm for 1 hour.

[0032] In the preparation process of modified polyetheramine D-2000: in step S1, after adding polyetheramine D-2000, hydroxyethyl acrylate and xylene into the reactor, the temperature is increased to 70°C, stirred for 1 hour, and then the temperature is increased to 100°C, and an initiator and a cross-linking agent are added thereto to continue the reaction for 4 hours; wherein the mass ratio of polyetheramine D-2000, hydroxyethyl acrylate, xylene, initiator and cross-linking agent is 1:3:12:0.5:0.08; the amount of the initiator in the system is 1.2 g / mL; in step S2, after diethylphosphite chloride is added dropwise, the reaction is continued for 4 hours; wherein the mass ratio of intermediate I, triethylamine, diethylphosphite chloride and anhydrous xylene is 6:1:5:15, and the amount of intermediate I in the system is 15 g / mL.

[0033] In the preparation process of a highly flame retardant protective composite fabric, the glue amount during lamination is 20g / m 2 The hot pressing temperature is 250℃, the hot pressing time is 15s, the hot pressing pressure is 4kgf / cm2, and the weight of the substrate is 180g / m 2 , thickness is 0.8mm, weight of thermal insulation layer is 180g / m 2 , thickness is 0.8mm.

[0034] Comparative Example 1

[0035] Compared with Example 1, this comparative example replaces the modified polyimide / polyether composite aerogel with a polyimide / polyether composite aerogel, specifically:

[0036] A highly flame-retardant protective composite fabric comprises a heat-insulating layer and a substrate; the heat-insulating layer is a polyimide / polyether composite aerogel, and the substrate is an aramid fiber felt.

[0037] The preparation method of polyimide / polyether composite aerogel is as follows: in a nitrogen atmosphere, 4,4'-diaminodiphenyl ether and polyetheramine D-2000 are dissolved in methyl pyrrolidone, and then 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride and pyridine are added thereto, and the reaction is carried out at 80°C for 3 hours, and then toluene is added, and the temperature is raised to 170°C for reaction for 5 hours. After the reaction is completed, the mixture is cooled to room temperature and precipitated into isopropanol, and then the mixture is dissolved in a saturated chloroform solution after filtration, and then poured into a mold for molding, and then the mixture is demolded after freeze drying, and then cooled to room temperature after three heatings to obtain a polyimide / polyether composite aerogel; wherein, 3,4, The mass ratio of 3',4'-diphenyl ether tetracarboxylic dianhydride, 4,4'-diaminodiphenyl ether and polyetheramine D-2000 is 13:12:1, the volume ratio of methyl pyrrolidone, pyridine and toluene is 55:1:50, and the amount of 4,4'-diaminodiphenyl ether in the system is 15 g / mL; wherein, the process of heating three times after freeze-drying and demoulding is as follows: heating to 100°C at a heating rate of 2°C / min and keeping warm for 1 hour, then heating to 200°C at a heating rate of 5°C / min and keeping warm for 1 hour, and finally heating to 300°C at a heating rate of 2°C / min and keeping warm for 1 hour.

[0038] The rest is as per Example 1.

[0039] Comparative Example 2

[0040] Compared with Example 1, the preparation method of the heat insulation layer in this comparative example is different, specifically:

[0041] A highly flame-retardant protective composite fabric, comprising a heat-insulating layer and a substrate;

[0042] The preparation method of the thermal insulation layer is as follows:

[0043] A1. After completely dissolving 4,4'-diaminodiphenyl ether in methyl pyrrolidone under a nitrogen atmosphere, 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added to the 4,4'-diaminodiphenyl ether solution, and the mixture was reacted in an ice-water bath for 6 hours. After the reaction was completed, the solvent was replaced with deionized water and freeze-dried to obtain a polymer powder; wherein the mass ratio of 3,3',4,4'-benzophenone tetracarboxylic dianhydride to 4,4'-diaminodiphenyl ether was 13:12, and the amount of 4,4'-diaminodiphenyl ether in the system was 15 g / mL;

[0044] A2. Add the polymer powder, triethylamine and polyetheramine D-2000 prepared in step A1 into deionized water, mix well and pour into a mold for molding, demold after freeze drying, and cool to room temperature after heating three times to obtain a mixed aerogel of polyimide and polyetheramine D-2000, wherein the mass ratio of the polymer powder, triethylamine and polyetheramine D-2000 is 15:1:1.5, the solid content in the system is 10%, and the heating process is: heating to 100° C. at a heating rate of 2° C. / min and keeping warm for 1 hour, then heating to 200° C. at a heating rate of 5° C. / min and keeping warm for 1 hour, and finally heating to 300° C. at a heating rate of 2° C. / min and keeping warm for 1 hour.

[0045] The rest is as per Example 1.

[0046] Comparative Example 3

[0047] Compared with Example 1, the preparation method of the heat insulation layer in this comparative example is different, specifically:

[0048] A highly flame-retardant protective composite fabric, comprising a heat-insulating layer and a substrate;

[0049] The preparation method of the thermal insulation layer is as follows:

[0050] A1. After completely dissolving 4,4'-diaminodiphenyl ether in methyl pyrrolidone under a nitrogen atmosphere, 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added to the 4,4'-diaminodiphenyl ether solution, and the mixture was reacted in an ice-water bath for 6 hours. After the reaction was completed, the solvent was replaced with deionized water and freeze-dried to obtain a polymer powder; wherein the mass ratio of 3,3',4,4'-benzophenone tetracarboxylic dianhydride to 4,4'-diaminodiphenyl ether was 13:12, and the amount of 4,4'-diaminodiphenyl ether in the system was 15 g / mL;

[0051] A2. Add the polymer powder and triethylamine prepared in step A1 to deionized water, mix well and pour into a mold to form, demold after freeze drying, and cool to room temperature after heating three times to obtain a polyimide aerogel, wherein the mass ratio of the polymer powder to the triethylamine is 15:1, the solid content in the system is 10%, and the heating process is: heating to 100° C. at a heating rate of 2° C. / min, keeping warm for 1 hour, then heating to 200° C. at a heating rate of 5° C. / min, keeping warm for 1 hour, and finally heating to 300° C. at a heating rate of 2° C. / min, keeping warm for 1 hour.

[0052] The rest is as per Example 1.

[0053] Related tests:

[0054] Fabric air permeability: The air permeability of the fabrics prepared in Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T5453-1997 “Determination of Air Permeability of Textile Fabrics”. The test results are shown in Table 1.

[0055] Table 1 Fabric air permeability test results

[0056] Group Air permeability (mm / s) Example 1 97 Example 2 96 Example 3 95 Comparative Example 1 83 Comparative Example 2 80 Comparative Example 3 74

[0057] Fabric wear resistance: The wear resistance of the fabrics prepared in Examples 1-3 and Comparative Examples 1-3 was tested according to the ASTM D3884 wear test method. The test results are shown in Table 2.

[0058] Table 2 Fabric wear resistance test results

[0059] Group Wear times (times) Example 1 8500 Example 2 8400 Example 3 8400 Comparative Example 1 7500 Comparative Example 2 7200 Comparative Example 3 6800

[0060] Flame retardant performance test: The combustion performance was tested with reference to GB / T5455-2014 standard on the fabrics prepared in Examples 1-3 and Comparative Examples 1-3. The sample size was 300×80 mm, the flame height was 4 cm, the sample ignition time was 12 s, and the afterflaming time and smoldering time were recorded. After removing the sample, the carbonized part was folded in half along the length direction, and a heavy hammer was hung at the lower end 6 mm away from the bottom and side edges. The other side of the lower end of the sample was lifted until the heavy hammer was suspended in the air, and the torn length of the sample was obtained, which was the damaged length. The test results are shown in Table 3.

[0061] Table 3 Test results of flame retardant properties of fabrics

[0062]

[0063] It can be seen from the test results in Table 1 and Table 2 that the air permeability and wear resistance of the composite fabrics prepared in Examples 1-3 are better than those prepared in Comparative Examples 1-3, especially the air permeability and wear resistance of the fabric prepared in Example 1 are the best; it can be seen from the test results in Table 3 that the afterflaming time, ignition time and damage length of the composite fabrics prepared in Examples 1-3 are all 0, and there is no dripping or melting phenomenon, indicating that the prepared composite fabric has excellent flame retardant properties; by comparing Example 1 with Comparative Example 1 (the thermal insulation layer is polyimide / polyether composite aerogel), Comparative Example 2 (the thermal insulation layer is a mixed aerogel of polyimide and polyetheramine D-2000) and Comparative Example 3 (the thermal insulation layer is polyimide aerogel), it can be seen that the modified polyimide / polyether composite aerogel synthesized by copolymerizing modified polyetheramine D-2000 as the thermal insulation layer has the best flame retardant effect.

[0064] Since the main chain of polyimide molecules contains a large number of aromatic heterocyclic structures, these structures have large bond energies and are not easy to break and decompose at high temperatures, so polyimide has excellent high temperature resistance; and the presence of these large numbers of rigid aromatic heterocyclics gives it good wear resistance. Aerogel is a porous ultra-light material. Due to its unique structure, it has the characteristics of low density and high efficiency thermal insulation. In the present invention, 4,4'-diaminodiphenyl ether, 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride and modified polyetheramine D-2000 are used to react to prepare a modified polyimide / polyether composite aerogel in which flexible chain molecules and rigid chain molecules are connected by covalent bonds. It has the advantages of high mechanical strength and excellent thermal stability of polyimide and low density and high efficiency thermal insulation of aerogel; in particular, in the preparation process of modified polyetheramine D-2000, dibenzoyl peroxide is used as an initiator and triallyl isocyanurate is used as a co-crosslinking agent to initiate. Polyetheramine D-2000 generates free radical reaction active sites, reacts with hydroxyethyl acrylate to form a free radical grafted onto the polyetheramine D-2000 molecular chain, and then reacts with diethylphosphite chloride to introduce a phosphorous acid group into its side chain. During combustion, PO· free radicals are generated, which capture the free radicals generated by combustion, delay the combustion chain reaction, and decompose and promote the polymer to form a barrier layer, inhibiting the generation and spread of flames. At high temperatures, it decomposes to generate flame-retardant gas, dilutes the concentration of combustible gas, and delays the spread of flames, so that the prepared fabric has good flame retardant properties.

[0065] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0066] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A highly flame retardant protective composite fabric, characterized in that: It comprises a heat-insulating layer and a substrate; the heat-insulating layer is a modified polyimide / polyether composite aerogel, and the substrate is an aramid fiber felt; The preparation method of the modified polyimide / polyether composite aerogel is as follows: under an inert atmosphere, 4,4'-diaminodiphenyl ether and modified polyether amine D-2000 are dissolved in methyl pyrrolidone, 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride and pyridine are added thereto, reacting at 75-85°C for 2-4h, adding toluene, heating to 165-185°C and reacting for 4-6h, cooling to room temperature after the reaction is completed, precipitating into isopropanol, filtering and dissolving in a saturated chloroform solution, pouring into a mold for molding, freeze-drying and demoulding, heating three times and then cooling to room temperature to obtain the modified polyimide / polyether composite aerogel; The preparation method of the modified polyetheramine D-2000 is: S1. In an inert atmosphere, add polyetheramine D-2000, hydroxyethyl acrylate and xylene to a reactor, raise the temperature to 60-70°C, stir for 1-2h, then raise the temperature to 100-110°C, add an initiator and a co-crosslinking agent, continue the reaction for 2-4h, cool to room temperature, filter, wash and dry to obtain intermediate I; S2. Add the intermediate I obtained in step S1, triethylamine and anhydrous xylene into the reactor, add diethylphosphite chloride dropwise under ice bath condition, continue the reaction for 2-4 hours after the addition is completed, remove the anhydrous xylene, add water and dichloromethane for extraction, collect the organic phase, and dry it to obtain modified polyetheramine D-2000.

2. A highly flame retardant protective composite fabric according to claim 1, characterized in that: The three heating processes after freeze-drying and demoulding are as follows: heating to 100°C at a heating rate of 2-4°C / min and keeping warm for 1-3h, then heating to 200°C at a heating rate of 3-5°C / min and keeping warm for 1-3h, and finally heating to 300°C at a heating rate of 2-4°C / min and keeping warm for 1-3h.

3. The highly flame retardant protective composite fabric according to claim 1, characterized in that: The mass ratio of 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride, 4,4'-diaminodiphenyl ether and modified polyetheramine D-2000 is 12-15:11-14:

1.

4. The highly flame retardant protective composite fabric according to claim 1, characterized in that: In step S1, the initiator is one or a mixture of cyclohexanone peroxide, dibenzoyl peroxide, and tert-butyl hydroperoxide.

5. The highly flame-retardant protective composite fabric according to claim 1, characterized in that: In step S1, the auxiliary cross-linking agent is triallyl isocyanurate.

6. The highly flame retardant protective composite fabric according to claim 1, characterized in that: In step S2, the mass ratio of intermediate I, triethylamine, diethylphosphite chloride and anhydrous xylene is 3-6:1:2-5:10-15.

7. A method for preparing a highly flame-retardant protective composite fabric, characterized in that: The preparation method prepares the highly flame-retardant protective composite fabric as described in any one of claims 1 to 6, and the preparation process is: the thermal insulation layer and the substrate are laminated and bonded to obtain the composite fabric, and the composite fabric is passed through the wave head of an ultrasonic sewing machine to make the fabric surface generate waves on the pattern roller to form a fabric surface with uniform pressure points, thereby obtaining the highly flame-retardant protective composite fabric.

8. The method for preparing the highly flame-retardant protective composite fabric according to claim 7, characterized in that: The base material has a grammage of 160-180 g / m 2 , thickness is 0.5-0.8mm, weight of thermal insulation layer is 160-180g / m 2 , thickness is 0.5-0.8mm.

9. The method for preparing the highly flame-retardant protective composite fabric according to claim 7, characterized in that: The adhesive used for lamination is polyurethane, and the amount of glue applied is 15-20g / m 2 , the hot pressing temperature is 240-250℃, the hot pressing time is 10-15s, and the hot pressing pressure is 3-4kgf / cm.

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