A method for preparing high-efficiency and durable flame-retardant nylon 6 fabric

Abstract

The present invention belongs to the technical field of flame-retardant fabrics, and relates to a method for preparing a highly efficient and durable flame-retardant nylon 6 fabric, specifically: after adding nylon 6 fabric to a finishing solution containing a reactive DOPO flame retardant, a polythiol compound, a photoinitiator and a solvent a, reacting for 2 to 3 hours at 20 to 30°C under UV light irradiation, a highly efficient and durable flame-retardant nylon 6 fabric is obtained; the limiting oxygen index of the highly efficient and durable flame-retardant nylon 6 fabric is higher than 29.8%, the damaged length is lower than 10.8 cm, no molten droplets are generated, and after 30 washes, the vertical combustion test can still be passed, the damaged length is lower than 14.1 cm, no molten droplets are generated, and the fabric has good flame retardant properties and water washability. The flame-retardant nylon 6 fabric prepared by the method of the present invention has a high limiting oxygen index, good flame retardant effect, no molten droplets are generated, and excellent water washability.

Description

Technical Field

[0001] The invention belongs to the technical field of flame-retardant fabrics, and in particular relates to a method for preparing a highly efficient and durable flame-retardant nylon 6 fabric. Background Art

[0002] As one of the earliest developed synthetic fibers, nylon 6 fiber is not only the leading product in the current nylon fiber series, but also occupies a leading position among all fibers due to its excellent wear resistance. In addition, nylon 6 is widely used in many fields such as bedding, luggage, curtains, home crafts, seat belts, industrial blankets and tents due to its low density and light weight. However, it is worth noting that nylon 6 fabric has the defect of being easy to burn and accompanied by severe molten droplets. In view of this characteristic, higher requirements are placed on the flame retardant properties of nylon 6 in key application areas such as outdoor equipment and work clothes to ensure the safety of users. At present, the development of efficient and durable flame retardant nylon 6 fabric is still a problem.

[0003] Reference (Flame retardant properties of nylon 66 fabric modified by microwave grafting [J]. Journal of Beijing University of Chemical Technology (Natural Science Edition), 2016, 43(2): 19-26.) used microwave technology to graft glycidyl methacrylate and DOPO onto the surface of nylon 66 fabric in sequence to prepare a flame retardant nylon 66 fabric that can withstand 10 washes.

[0004] Patent application CN116516679A discloses a durable flame retardant and drip-proof coating nylon 6 fabric and a preparation method thereof, wherein polyacrylamide, terephthalaldehyde and DOPO are dissolved in a mixed solution of ethanol and water for reaction to obtain modified polyacrylamide; the modified polyacrylamide is dissolved in a solvent, and the nylon 6 fabric is immersed in the solvent, and the durable flame retardant and drip-proof coating nylon 6 fabric is prepared by a padding-baking process. However, polyacrylamide and modified polyacrylamide have a high viscosity after being dissolved, and the viscous liquid weakens its fluidity, making it difficult to apply to textiles, and a lower amount of modified polyacrylamide cannot provide good flame retardant properties and water washability.

[0005] Patent application CN116217623A discloses a bio-based flame retardant and its preparation method and application. The bio-based flame retardant is synthesized by using DOPO and allylthiourea, and then dialdehyde is used as a cross-linking agent to improve the fixation of the bio-based flame retardant on polyamide 56 fabric, which can withstand 25 washes. However, the active amino groups on polyamide 56 fabric are limited, and the content of bio-based flame retardant that can be grafted is limited. The water washability of flame-retardant polyamide fabric still needs to be further improved.

[0006] Therefore, it is necessary to develop a method for preparing an efficient and durable flame-retardant nylon 6 fabric to improve the flame retardancy and durability of the nylon 6 fabric. Summary of the invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for preparing a highly efficient and durable flame-retardant nylon 6 fabric.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a highly efficient and durable flame-retardant nylon 6 fabric, wherein the nylon 6 fabric is added to a finishing solution containing a reactive DOPO flame retardant, a polythiol compound, a photoinitiator and a solvent a (such as acetone), and the mixture is reacted at 20 to 30° C. under UV light for 2 to 3 hours to obtain a highly efficient and durable flame-retardant nylon 6 fabric, wherein the reactive DOPO flame retardant has the following structural formula:

[0010]

[0011] On the one hand, under the catalysis and initiation of UV light, the vinyl double bonds of the reactive DOPO flame retardant undergo a click chemical reaction with the thiol groups of the polythiol compound, and both ends of the reactive DOPO flame retardant contain vinyl double bonds, which can react with themselves to undergo polymerization, thereby polymerizing on the surface of nylon 6 fabric; on the other hand, the unreacted thiol groups in the polymerization product can undergo covalent bonds with the amino groups on the surface of the nylon 6 fabric, thereby grafting the polymer onto the nylon 6 fabric, thereby providing durable flame retardant properties.

[0012] As the preferred technical solution:

[0013] In the method for preparing a highly efficient and durable flame-retardant nylon 6 fabric as described above, the polythiol compound is one or more of dithiol, 2,2-(1,2-ethylenedioxy)bisthiol, 1,2,3-trimercaptopropane and dithiol polyethylene glycol; and the photoinitiator is benzoin dimethyl ether.

[0014] As described above, in the preparation method of a highly efficient and durable flame-retardant nylon 6 fabric, in the finishing liquid, the concentration of the polythiol compound is 25-40 g / L, the concentration of the reactive DOPO flame retardant is 40-70 g / L, the higher the concentration of the flame retardant, the higher the flame retardant effect, but too high a concentration is wasteful, and the concentration of the photoinitiator is 20-30 g / L.

[0015] In the method for preparing a highly efficient and durable flame-retardant nylon 6 fabric as described above, the mass ratio of the nylon 6 fabric to the finishing liquid is 1:30-40.

[0016] In the method for preparing a highly efficient and durable flame-retardant nylon 6 fabric as described above, the wavelength of the UV lamp is 365nm, and the irradiation intensity is 80-100μW / cm -2 .

[0017] The preparation method of the high-efficiency and durable flame-retardant nylon 6 fabric as described above, the preparation steps of the reactive DOPO flame retardant are as follows:

[0018] (a) DOPO, 1,5-dihydroxy-3-pentanone, and solvent b (N,N-dimethylformamide) are mixed and reacted;

[0019] (b) After cooling to 20-30° C., methacryloyl chloride and triethylamine are added to continue the reaction to obtain a reactive DOPO flame retardant;

[0020] DOPO reacts with the keto group of 1,5-dihydroxy-3-pentanone to generate an intermediate product, and the acyl chloride group of methacryloyl chloride reacts with the hydroxyl group of the intermediate product to generate hydrogen chloride by nucleophilic substitution reaction. Adding triethylamine as an acid absorber helps to promote the reaction.

[0021] As described above, a method for preparing a high-efficiency, durable flame-retardant nylon 6 fabric, in step (a), the molar ratio of DOPO to 1,5-dihydroxy-3-pentanone is 2 to 2.2:1. Theoretically, the PH bond of two moles of DOPO reacts with the ketone group of 1,5-dihydroxy-3-pentanone to form an intermediate product. A slight excess of DOPO helps to promote the complete reaction. The mass ratio of DOPO to solvent b is 1:30 to 40, the reaction temperature is 140 to 150°C, and the reaction time is 4 to 5 hours.

[0022] According to the method for preparing a highly efficient and durable flame-retardant nylon 6 fabric, the molar ratio of methacryloyl chloride in step (b) to 1,5-dihydroxy-3-pentanone in step (a) is 2 to 2.2:1. Theoretically, the hydroxyl groups on both sides of 1,5-dihydroxy-3-pentanone can react with two moles of methacryloyl chloride. A slight excess of methacryloyl chloride helps to promote the complete reaction. In step (b), the molar ratio of triethylamine to methacryloyl chloride is 1 to 1.1:1, and the reaction is continued for 8 to 10 hours.

[0023] A method for preparing a high-efficiency, long-lasting flame-retardant nylon 6 fabric as described in any of the above items, wherein the high-efficiency, long-lasting flame-retardant nylon 6 fabric has a limiting oxygen index higher than 29.8%, a damaged length lower than 10.8 cm, no molten droplets are generated, and can still pass the vertical burning test after 30 washes, with a damaged length lower than 14.1 cm, no molten droplets are generated, and has good flame retardant properties and water washability.

[0024] Principle of the invention:

[0025] Schematic diagram of the synthesis route of reactive DOPO flame retardant Figure 1 As shown, the PH bond of DOPO can undergo addition reaction with the keto group of 1,5-dihydroxy-3-pentanone to generate a DOPO-based intermediate product with hydroxyl groups at both ends, and the acyl chloride group of methacryloyl chloride undergoes nucleophilic substitution reaction with the hydroxyl group of the intermediate product to prepare a reactive DOPO flame retardant.

[0026] Both ends of the reactive DOPO flame retardant contain vinyl double bonds. On the one hand, under the catalysis and initiation of UV light, the vinyl double bonds of the reactive DOPO flame retardant react with the thiol groups of the polythiol compound in a click chemical reaction. Both ends of the reactive DOPO flame retardant contain vinyl double bonds, which can undergo polymerization reaction by itself, thereby polymerizing on the surface of nylon 6 fabric. On the other hand, the unreacted thiol groups in the polymerization product can be covalently bonded with the amino groups on the surface of nylon 6 fabric, thereby grafting the polymer onto the nylon 6 fabric, thereby providing durable flame retardant properties.

[0027] The polymer is rich in phosphorus-containing groups, which mainly improve the flame retardant properties of nylon 6 fabric through the gas phase mechanism. Phosphorus-containing free radicals are generated during the combustion process, which can capture the combustible free radicals in the combustion area, play a quenching role, and improve the flame retardant properties of nylon 6 fabric.

[0028] Beneficial effects:

[0029] (1) The vinyl double bonds of the reactive DOPO flame retardant synthesized by the present invention undergo a click chemical reaction with the thiol groups of the polythiol compound, so that the reactive DOPO flame retardant and the polythiol compound are polymerized on the surface of the nylon 6 fabric and grafted onto the nylon 6 fabric through covalent bonds, thereby giving the flame-retardant nylon 6 fabric a long-lasting water-resistant performance;

[0030] (2) The phosphorus-containing groups of the reactive DOPO flame retardant synthesized by the present invention and the sulfur-containing groups of the polythiol compound can improve the flame retardancy of nylon 6 fabric through synergistic flame retardancy, and the flame retardancy efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the synthesis route of the reactive DOPO flame retardant synthesized in the present invention;

[0032] Figure 2 This is the carbon nuclear magnetic resonance spectrum of the reactive DOPO flame retardant prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0034] Testing methods for relevant performance indicators:

[0035] Limiting oxygen index: Tested in accordance with GB / T 5454-1997 "Oxygen Index Method for Textile Combustion Performance Test".

[0036] Damage length and the presence of molten droplets: Determine the damage length, smoldering and afterflaming time in the vertical direction of the combustion performance of textiles according to GB / T 5455-2014. Observe the presence of molten droplets during the test.

[0037] Damaged length and presence of molten droplets after 30 washes: First wash the fabric 30 times with water according to AATCC 61-2013 "Accelerated test for color fastness to household and commercial washing" standard, and then test the damaged length of the fabric with reference to GB / T 5455-2014 "Determination of vertical direction damage length, smoldering and afterflaming time of textile combustion performance" standard, and observe whether there are molten droplets during the test.

[0038] The structural formula of the reactive DOPO flame retardant prepared in the following examples is as follows:

[0039]

[0040] A method for preparing a highly efficient and durable flame-retardant nylon 6 fabric, the specific steps are as follows:

[0041] (1) Raw material preparation:

[0042] Nylon 6 fabric: damaged length is 30cm, limiting oxygen index is 20.1%;

[0043] Polythiol compounds: dithiols;

[0044] Photoinitiator: dimethyl benzoate;

[0045] DOPO;

[0046] 1,5-dihydroxy-3-pentanone;

[0047] Methacryloyl chloride;

[0048] Triethylamine;

[0049] Solvent a: acetone;

[0050] Solvent b: N,N-dimethylformamide;

[0051] (2) Preparation of reactive DOPO flame retardant:

[0052] (2.1) DOPO, 1,5-dihydroxy-3-pentanone and solvent b were mixed and reacted at 140°C for 5 hours;

[0053] The molar ratio of DOPO to 1,5-dihydroxy-3-pentanone was 2:1, and the mass ratio of DOPO to solvent b was 1:30;

[0054] (2.2) After cooling to 20°C, methacryloyl chloride and triethylamine were added and the reaction was continued for 10 hours to obtain a reactive DOPO flame retardant;

[0055] Wherein, the molar ratio of methacryloyl chloride to 1,5-dihydroxy-3-pentanone in step (2.1) is 2:1, and the molar ratio of triethylamine to methacryloyl chloride is 1:1;

[0056] The carbon NMR spectrum of the prepared reactive DOPO flame retardant is as follows: Figure 2 As shown in the figure, it can be seen that the chemical shifts at 7.51, 7.32, 7.08, 6.89 and ppm in the nuclear magnetic resonance hydrogen spectrum of the reactive DOPO flame retardant are caused by the hydrogen elements of the benzene ring in the DOPO structure, the chemical shifts at 6.19 and 5.62ppm are caused by the hydrogen elements of the double bond structure of the propylene group, the chemical shift at 1.91ppm is caused by the hydrogen element on the methyl group in methacryloyl chloride, and the chemical shift at 4.35ppm is caused by the hydrogen element of CH2 in the 1,5-dihydroxy-3-pentanone structure. The above results show that the reactive DOPO flame retardant was successfully synthesized;

[0057] (3) Flame retardant finishing:

[0058] After adding nylon 6 fabric into a finishing solution composed of reactive DOPO flame retardant, polythiol compound, photoinitiator and solvent a, the fabric was reacted at 20°C under UV light for 3 hours to obtain a highly efficient and durable flame retardant nylon 6 fabric.

[0059] In the finishing liquid, the concentration of polythiol compound is 25g / L, the concentration of reactive DOPO flame retardant is 40g / L, and the concentration of photoinitiator is 20g / L; the mass ratio of nylon 6 fabric to finishing liquid is 1:30; the wavelength of UV lamp is 365nm, and the irradiation intensity is 80μW / cm -2 .

[0060] The final high-efficiency and durable flame-retardant nylon 6 fabric had a limiting oxygen index of 29.8%, a damaged length of 10.8 cm, and no molten droplets were generated. After 30 washes, the damaged length was 14.1 cm, and no molten droplets were generated.

[0061] Comparative Example 1

[0062] A method for preparing a flame-retardant nylon 6 fabric is basically the same as that in Example 1, except that: in the finishing liquid of step (3) of this comparative example, flame retardant a is used to replace the reactive DOPO flame retardant in the original Example 1, and the synthesis step of flame retardant a is basically the same as that in step (2) of Example 1, except that methacryloyl chloride is not added.

[0063] The final flame retardant nylon 6 fabric had a limiting oxygen index of 28.8%, a damaged length of 12.3 cm, and no droplets were generated. After 30 washes, the damaged length was 30 cm and droplets were generated.

[0064] Compared with Example 1, the flame retardant performance of the flame retardant nylon 6 fabric in Comparative Example 1 is reduced, and the water washing resistance is poor. This is because the flame retardant a in Comparative Example 1 does not contain vinyl double bonds at both ends, cannot be polymerized on the surface of the nylon 6 fabric, and cannot react with the nylon 6 fabric. It is simply deposited on the surface of the nylon 6 fabric, which reduces the flame retardant and durability of the flame retardant nylon 6 fabric finally obtained.

[0065] Comparative Example 2

[0066] A method for preparing a flame retardant nylon 6 fabric is basically the same as that in Example 1, except that ammonium sulfate is used in this comparative example instead of the polythiol compound in Example 1.

[0067] The final flame retardant nylon 6 fabric had a limiting oxygen index of 29.1%, a damaged length of 11.4 cm, and no droplets were generated. After 30 washes, the damaged length was 30 cm and droplets were generated.

[0068] Compared with Example 1, the flame retardant and washability of the flame retardant nylon 6 fabric in Comparative Example 2 are reduced. This is because the ammonium sulfate used in Comparative Example 2 does not contain a thiol group and cannot undergo a click chemistry reaction with the reactive DOPO flame retardant. In addition, the degree of self-polymerization of the DOPO flame retardant is low under this condition and cannot form a polymer on the surface of the nylon 6 fabric. Only a small amount of covalent bonds grafted to the nylon 6 fabric cannot provide good washability. Therefore, the flame retardant and washability of the flame retardant nylon 6 fabric in Comparative Example 2 deteriorate.

[0069] Comparative Example 3

[0070] A method for preparing a flame retardant nylon 6 fabric is basically the same as that of Example 1, except that there is no photoinitiator in this comparative example.

[0071] The final flame retardant nylon 6 fabric had a limiting oxygen index of 29.3%, a damaged length of 11.2 cm, and droplets were generated. After 30 washes, the damaged length was 30 cm, and droplets were generated.

[0072] Compared with Example 1, the flame retardant properties of the flame retardant nylon 6 fabric of Comparative Example 3 are reduced, and the water washing resistance is reduced. This is because Comparative Example 3 lacks a photoinitiator, resulting in a small degree of click chemical reaction between the reactive DOPO flame retardant and the polythiol compound, and a small degree of polymerization reaction between the reactive DOPO flame retardant itself. The reactive DOPO flame retardant cannot be polymerized on the surface of the nylon 6 fabric, and is mainly deposited on the nylon 6 fabric in a single molecule state. Therefore, the flame retardant and water washing resistance of the flame retardant nylon 6 fabric of Comparative Example 3 deteriorate.

[0073] Example 2

[0074] A method for preparing a highly efficient and durable flame-retardant nylon 6 fabric, the specific steps are as follows:

[0075] (1) Raw material preparation:

[0076] Nylon 6 fabric: damaged length is 30cm, limiting oxygen index is 20.1%;

[0077] Polythiol compounds: 2,2-(1,2-ethylenedioxy)bis(ethanethiol);

[0078] Photoinitiator: dimethyl benzoate;

[0079] DOPO;

[0080] 1,5-dihydroxy-3-pentanone;

[0081] Methacryloyl chloride;

[0082] Triethylamine;

[0083] Solvent a: acetone;

[0084] Solvent b: N,N-dimethylformamide;

[0085] (2) Preparation of reactive DOPO flame retardant:

[0086] (2.1) DOPO, 1,5-dihydroxy-3-pentanone and solvent b were mixed and reacted at 142°C for 4.8 hours;

[0087] Among them, the molar ratio of DOPO to 1,5-dihydroxy-3-pentanone is 2.1:1, and the mass ratio of DOPO to solvent b is 1:35;

[0088] (2.2) After cooling to 23°C, methacryloyl chloride and triethylamine were added and the reaction was continued for 9.5 hours to obtain a reactive DOPO flame retardant;

[0089] Wherein, the molar ratio of methacryloyl chloride to 1,5-dihydroxy-3-pentanone in step (2.1) is 2.1:1, and the molar ratio of triethylamine to methacryloyl chloride is 1.1:1;

[0090] (3) Flame retardant finishing:

[0091] After adding nylon 6 fabric into a finishing solution composed of reactive DOPO flame retardant, polythiol compound, photoinitiator and solvent a, the fabric was reacted at 22°C under UV light for 2.8 hours to obtain a highly efficient and durable flame retardant nylon 6 fabric.

[0092] In the finishing liquid, the concentration of polythiol compound is 30g / L, the concentration of reactive DOPO flame retardant is 50g / L, and the concentration of photoinitiator is 22g / L; the mass ratio of nylon 6 fabric to finishing liquid is 1:35; the wavelength of UV lamp is 365nm, and the irradiation intensity is 85μW / cm -2 .

[0093] The final high-efficiency and durable flame-retardant nylon 6 fabric had a limiting oxygen index of 30.8%, a damaged length of 9.5 cm, and no molten droplets were generated. After 30 washes, the damaged length was 13.7 cm, and no molten droplets were generated.

[0094] Example 3

[0095] A method for preparing a highly efficient and durable flame-retardant nylon 6 fabric, the specific steps are as follows:

[0096] (1) Raw material preparation:

[0097] Nylon 6 fabric: damaged length is 30cm, limiting oxygen index is 20.1%;

[0098] Polymercapto compounds: 1,2,3-trimercaptopropane;

[0099] Photoinitiator: dimethyl benzoate;

[0100] DOPO;

[0101] 1,5-dihydroxy-3-pentanone;

[0102] Methacryloyl chloride;

[0103] Triethylamine;

[0104] Solvent a: acetone;

[0105] Solvent b: N,N-dimethylformamide;

[0106] (2) Preparation of reactive DOPO flame retardant:

[0107] (2.1) DOPO, 1,5-dihydroxy-3-pentanone and solvent b were mixed and reacted at 145°C for 4.5 hours;

[0108] The molar ratio of DOPO to 1,5-dihydroxy-3-pentanone was 2.2:1, and the mass ratio of DOPO to solvent b was 1:40;

[0109] (2.2) After cooling to 25°C, methacryloyl chloride and triethylamine were added and the reaction was continued for 9 hours to obtain a reactive DOPO flame retardant;

[0110] Wherein, the molar ratio of methacryloyl chloride to 1,5-dihydroxy-3-pentanone in step (2.1) is 2.2:1, and the molar ratio of triethylamine to methacryloyl chloride is 1:1;

[0111] (3) Flame retardant finishing:

[0112] After adding nylon 6 fabric into a finishing solution composed of a reactive DOPO flame retardant, a polythiol compound, a photoinitiator and a solvent a, the fabric was reacted at 25°C under UV light for 2.5 hours to obtain a highly efficient and durable flame retardant nylon 6 fabric.

[0113] In the finishing liquid, the concentration of polythiol compound is 35g / L, the concentration of reactive DOPO flame retardant is 55g / L, and the concentration of photoinitiator is 25g / L; the mass ratio of nylon 6 fabric to finishing liquid is 1:40; the wavelength of UV lamp is 365nm, and the irradiation intensity is 90μW / cm -2 .

[0114] The final high-efficiency and durable flame-retardant nylon 6 fabric had a limiting oxygen index of 31.6%, a damaged length of 8.9 cm, and no molten droplets were generated. After 30 washes, the damaged length was 13.4 cm, and no molten droplets were generated.

[0115] Example 4

[0116] A method for preparing a highly efficient and durable flame-retardant nylon 6 fabric, the specific steps are as follows:

[0117] (1) Raw material preparation:

[0118] Nylon 6 fabric: damaged length is 30cm, limiting oxygen index is 20.1%;

[0119] Polythiol compound: dithiol polyethylene glycol (molecular weight 2000, purchased from Shenzhen Meiluo Technology Co., Ltd.);

[0120] Photoinitiator: dimethyl benzoate;

[0121] DOPO;

[0122] 1,5-dihydroxy-3-pentanone;

[0123] Methacryloyl chloride;

[0124] Triethylamine;

[0125] Solvent a: acetone;

[0126] Solvent b: N,N-dimethylformamide;

[0127] (2) Preparation of reactive DOPO flame retardant:

[0128] (2.1) DOPO, 1,5-dihydroxy-3-pentanone and solvent b were mixed and reacted at 148°C for 4.3 hours;

[0129] Among them, the molar ratio of DOPO to 1,5-dihydroxy-3-pentanone is 2.1:1, and the mass ratio of DOPO to solvent b is 1:35;

[0130] (2.2) After cooling to 28°C, methacryloyl chloride and triethylamine were added and the reaction was continued for 8.5 hours to obtain a reactive DOPO flame retardant;

[0131] Wherein, the molar ratio of methacryloyl chloride to 1,5-dihydroxy-3-pentanone in step (2.1) is 2.1:1, and the molar ratio of triethylamine to methacryloyl chloride is 1.1:1;

[0132] (3) Flame retardant finishing:

[0133] After adding nylon 6 fabric into a finishing solution composed of reactive DOPO flame retardant, polythiol compound, photoinitiator and solvent a, the fabric was reacted at 28°C under UV light for 2.3 hours to obtain a highly efficient and durable flame retardant nylon 6 fabric.

[0134] In the finishing liquid, the concentration of polythiol compound is 38g / L, the concentration of reactive DOPO flame retardant is 60g / L, and the concentration of photoinitiator is 28g / L; the mass ratio of nylon 6 fabric to finishing liquid is 1:30; the wavelength of UV lamp is 365nm, and the irradiation intensity is 95μW / cm -2 .

[0135] The final high-efficiency and durable flame-retardant nylon 6 fabric had a limiting oxygen index of 32.2%, a damaged length of 8.5 cm, and no molten droplets were generated. After 30 washes, the damaged length was 13.2 cm, and no molten droplets were generated.

[0136] Example 5

[0137] A method for preparing a highly efficient and durable flame-retardant nylon 6 fabric, the specific steps are as follows:

[0138] (1) Raw material preparation:

[0139] Nylon 6 fabric: damaged length is 30cm, limiting oxygen index is 20.1%;

[0140] Polythiol compound: a mixture of dithiol and dithiol polyethylene glycol (molecular weight 2000, purchased from Shenzhen Meiluo Technology Co., Ltd.) in a mass ratio of 1:1;

[0141] Photoinitiator: dimethyl benzoate;

[0142] DOPO;

[0143] 1,5-dihydroxy-3-pentanone;

[0144] Methacryloyl chloride;

[0145] Triethylamine;

[0146] Solvent a: acetone;

[0147] Solvent b: N,N-dimethylformamide;

[0148] (2) Preparation of reactive DOPO flame retardant:

[0149] (2.1) DOPO, 1,5-dihydroxy-3-pentanone and solvent b were mixed and reacted at 150°C for 4 hours;

[0150] The molar ratio of DOPO to 1,5-dihydroxy-3-pentanone was 2:1, and the mass ratio of DOPO to solvent b was 1:30;

[0151] (2.2) After cooling to 30°C, methacryloyl chloride and triethylamine were added and the reaction was continued for 8 hours to obtain a reactive DOPO flame retardant;

[0152] Wherein, the molar ratio of methacryloyl chloride to 1,5-dihydroxy-3-pentanone in step (2.1) is 2:1, and the molar ratio of triethylamine to methacryloyl chloride is 1.1:1;

[0153] (3) Flame retardant finishing:

[0154] After adding nylon 6 fabric into a finishing solution composed of reactive DOPO flame retardant, polythiol compound, photoinitiator and solvent a, the fabric was reacted at 30°C under UV light for 2 hours to obtain a highly efficient and durable flame retardant nylon 6 fabric.

[0155] In the finishing liquid, the concentration of polythiol compound is 40g / L, the concentration of reactive DOPO flame retardant is 70g / L, and the concentration of photoinitiator is 30g / L; the mass ratio of nylon 6 fabric to finishing liquid is 1:35; the wavelength of UV lamp is 365nm, and the irradiation intensity is 100μW / cm -2 .

[0156] The final high-efficiency and durable flame-retardant nylon 6 fabric had a limiting oxygen index of 32.5%, a damaged length of 8.3 cm, and no molten droplets were generated. After 30 washes, the damaged length was 12.9 cm, and no molten droplets were generated.

Claims

1. A method for preparing a highly efficient and durable flame-retardant nylon 6 fabric, characterized in that: After adding nylon 6 fabric into a finishing solution containing reactive DOPO flame retardant, polythiol compound, photoinitiator and solvent a, the fabric is reacted at 20-30°C under UV light for 2-3 hours to obtain high-efficiency and durable flame-retardant nylon 6 fabric, wherein the polythiol compound is one or more of dithiol, 2,2-(1,2-ethylenedioxy)bisethylmercaptan, 1,2,3-trimercaptopropane and bismercapto polyethylene glycol, and the reactive DOPO flame retardant has the following structural formula:

2. The method for preparing a high-efficiency and durable flame-retardant nylon 6 fabric according to claim 1, characterized in that: The photoinitiator is dimethyl benzoate.

3. The method for preparing a high-efficiency and durable flame-retardant nylon 6 fabric according to claim 1, characterized in that: In the finishing liquid, the concentration of the polythiol compound is 25-40 g / L, the concentration of the reactive DOPO flame retardant is 40-70 g / L, and the concentration of the photoinitiator is 20-30 g / L.

4. The method for preparing a high-efficiency and durable flame-retardant nylon 6 fabric according to claim 1, characterized in that: The mass ratio of nylon 6 fabric to finishing liquid is 1:30-40.

5. The method for preparing a high-efficiency and durable flame-retardant nylon 6 fabric according to claim 1, characterized in that: The wavelength of UV lamp is 365nm, and the irradiation intensity is 80~100μW / cm 2 .

6. The method for preparing a high-efficiency and durable flame-retardant nylon 6 fabric according to claim 1, characterized in that: The preparation steps of reactive DOPO flame retardant are as follows: (a) mixing DOPO, 1,5-dihydroxy-3-pentanone and solvent b and reacting; (b) After cooling to 20-30° C., methacryloyl chloride and triethylamine are added to continue the reaction to obtain a reactive DOPO flame retardant.

7. The method for preparing a high-efficiency and durable flame-retardant nylon 6 fabric according to claim 6, characterized in that: In step (a), the molar ratio of DOPO to 1,5-dihydroxy-3-pentanone is 2-2.2:1, the mass ratio of DOPO to solvent b is 1:30-40, the reaction temperature is 140-150° C., and the reaction time is 4-5 h.

8. The method for preparing a high-efficiency and durable flame-retardant nylon 6 fabric according to claim 6, characterized in that: The molar ratio of methacryloyl chloride in step (b) to 1,5-dihydroxy-3-pentanone in step (a) is 2 to 2.2:1; in step (b), the molar ratio of triethylamine to methacryloyl chloride is 1 to 1.1:1, and the reaction is continued for 8 to 10 hours.

9. A method for preparing a high-efficiency and durable flame-retardant nylon 6 fabric according to any one of claims 1 to 8, characterized in that: The limiting oxygen index of the high-efficiency and long-lasting flame-retardant nylon 6 fabric is higher than 29.8%, the damaged length is less than 10.8cm, and no molten droplets are generated. After 30 washes, it can still pass the vertical burning test, with the damage length less than 14.1cm and no molten droplets generated.

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