Preparation method of moisture-absorbing and flame-retardant polyamide and fiber

Abstract

The application relates to the technical field of polyamide synthesis modification and fiber preparation, in particular to a preparation method of moisture-absorbing and flame-retardant polyamide and fiber. The preparation method of the moisture-absorbing and flame-retardant polyamide comprises the following steps: (1) a flame retardant with a carboxyl group is salted with a salt-forming polyether amine to obtain a flame retardant salt; and (2) polyamide monomers, the flame retardant salt and a moisture-absorbing modification polyether amine are copolymerized to obtain the moisture-absorbing and flame-retardant polyamide. In the preparation method, the flame retardant with the carboxyl group is pre-salted with the salt-forming polyether amine, and then participates in the copolymerization of the polyamide, so that the dispersibility of the flame retardant in the polyamide is improved, and the flame-retardant effect is better; the salt-forming polyether amine and the moisture-absorbing modification polyether amine participate in the copolymerization of the polyamide, so that the polyether amine is uniformly dispersed in the polyamide; the moisture-absorbing property of the polyamide is improved to a large extent by using the strong moisture-absorbing property of the polyether amine and the amide bond formed between the polyether amine and the polyamide monomers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyamide synthesis modification and fiber preparation, and particularly relates to a moisture-absorbing and flame-retardant polyamide and a preparation method of fibers. BACKGROUND

[0002] As a common polymer material, polyamide fiber is a fiber-forming polymer with each chain segment in the macromolecular chain connected by an amide bond, also known as nylon or chinlon. Compared with polyester and acrylic fiber, chinlon has higher moisture absorption, but still has a gap compared with natural fibers. When used in clothing, bed sheets and special fabrics that come into contact with the skin, poor moisture absorption will cause a stuffy feeling, affecting the overall comfort. At the same time, as a typical polymer material, the flame retardant performance of polyamide is poor, which is not enough to be applied to the flame retardant field. It is necessary to develop moisture-absorbing and flame-retardant polyamide fibers for the safety of the application scene and the overall comfort and air permeability of the fibers.

[0003] Patent CN113337910A discloses a white graphene moisture-absorbing and sweat-releasing cool chinlon staple fiber and a preparation method thereof. The ground chinlon chip is mixed with white graphene microsheet and modifiers such as polyethylene glycol to form granules, the composite master batch is filtered and spun through a cross-shaped spinning hole, and finally the composite profiled yarn is treated with alkali and dried and cut to obtain a fiber with moisture absorption, sweat release, cool feeling and antibacterial property. This method combines physical modification and later alkali treatment, and the preparation process is relatively complex. At the same time, there is a problem of poor dispersibility of the modifier, which limits the effect of the modifier on improving the moisture absorption of the fiber.

[0004] Patent CN107573504A discloses a preparation method of moisture-absorbing and flame-retardant nylon and fibers. A flame-retardant prepolymer is obtained by polymerizing a phosphorus-containing flame retardant, a diamine and an aliphatic diol in water, and then a moisture-absorbing and flame-retardant nylon is obtained by adding a sulfonate moisture-absorbing monomer and a flame retardant prepolymer during the polymerization of nylon 66. The fiber obtained in this way has good moisture absorption and flame retardance. This method belongs to chemical modification and combines the two characteristics of flame retardance and moisture absorption. However, the patent directly mixes the phosphorus-based flame retardant with the diamine and the aliphatic diol to pre-polymerize, which has the problem of poor dispersibility of the flame retardant. SUMMARY

[0005] In order to solve the technical problem of poor dispersibility of the moisture-absorbing modifier and the flame retardant in the existing polyamide moisture-absorbing and flame-retardant modification method, the present application provides a preparation method of moisture-absorbing and flame-retardant polyamide. In the preparation method, the flame retardant with carboxyl is pre-salted with salt-forming polyether amine, and then copolymerized with polyamide monomer and moisture-absorbing modification polyether amine. The flame retardant and the moisture-absorbing modifier (polyether amine) can be uniformly distributed in the polyamide, thereby greatly improving the flame retardance and moisture absorption of the polyamide.

[0006] The specific technical scheme of the present application is:

[0007] In a first aspect, the present application provides a preparation method of moisture-absorbing and flame-retardant polyamide, comprising the following steps:

[0008] (1) salifying the flame retardant with carboxyl group with salt-forming polyether amine to obtain flame retardant salt;

[0009] (2) copolymerizing polyamide monomer, flame retardant salt and moisture-absorbing modification polyether amine to obtain moisture-absorbing and flame-retardant polyamide.

[0010] The polyether amine has amino group at both ends of the molecular chain, which can be salified with the carboxyl group in the flame retardant, and then the flame retardant salt is used to participate in the copolymerization of polyamide, which can improve the dispersibility of the flame retardant in the moisture-absorbing and flame-retardant polyamide, thereby improving the flame-retardant effect. The polyether amine itself has strong moisture-absorbing property, and the amide bond formed by the reaction of the polyether amine and the polyamide monomer (diacid) is a polar and moisture-absorbing group. Therefore, by introducing the polyether amine (including salt-forming polyether amine and moisture-absorbing modification polyether amine) into the polyamide, the moisture-absorbing property of the polyamide can be improved; and the polyether amine can participate in the copolymerization of the polyamide by using the amino group therein, so that it can be uniformly distributed in the finally obtained moisture-absorbing and flame-retardant polyamide, thereby playing a better moisture-absorbing modification role.

[0011] Preferably, in step (2), the molecular weight of the moisture-absorbing modification polyether amine is 100-5000 Da, and the polyether chain therein is one or more of polyethylene oxide, polypropylene oxide, polybutylene oxide, block copolymer composed of polyethylene oxide and polypropylene oxide, and block copolymer composed of polyethylene oxide and polybutylene oxide.

[0012] Further, in step (2), the polyether chain in the moisture-absorbing modification polyether amine is a block copolymer composed of polyethylene oxide and poly 2,3-epoxy butane, and the preparation method comprises the following steps: mixing ethylene glycol and potassium hydroxide, then adding ethylene oxide under the protection of inert gas, reacting at 110-120℃ and 0.2-0.3MPa for 3-3.5h, then adding 2,3-epoxy butane, and continuing to react at 110-120℃ and 0.2-0.3MPa for 2-2.5h to obtain block polyether; and then aminating the block polyether to obtain the moisture-absorbing modification polyether amine; the molar ratio of the ethylene glycol, ethylene oxide and 2,3-epoxy butane is 1:17.8-19.0:1.7-1.9, and the amount of potassium hydroxide is 35-38wt% of the ethylene glycol.

[0013] When the polyether chain in the polyether amine for moisture modification is a block copolymer composed of polyethylene oxide and poly-2,3-epoxybutane, the polyethylene oxide segment has higher hydrophilicity, the poly-2,3-epoxybutane segment can better reduce the crystallinity of the polyamide, and the two segments cooperate with each other to promote the absorption and diffusion of moisture in the polyamide to a greater extent and improve the moisture absorption of the polyamide; in addition, compared with the polyethylene oxide segment, the poly-2,3-epoxybutane segment can also make the polyamide more stable during the spinning process, so that the polyamide fiber has higher strength.

[0014] In the preparation process of the block polyether, the amount of ethylene oxide and 2,3-epoxybutane and the reaction time will affect the content of the polyethylene oxide and poly-2,3-epoxybutane segments in the final obtained polyether amine. When the relative content of the polyethylene oxide segment in the polyether amine is too large, the polyamide prepared by using the polyether amine for moisture modification will have the phenomenon of system tackiness and unstable molding during the spinning process, resulting in lower strength of the polyamide fiber; when the relative content of the poly-2,3-epoxybutane segment in the polyether amine is too large, the hydrophilicity of the polyether amine will be reduced to a certain extent, and then the moisture absorption of the polyamide will be lower. Based on this, the amount of ethylene oxide and 2,3-epoxybutane and the reaction time are controlled within the above specific range, so that the polyether amine can improve the moisture absorption of the polyamide to a greater extent, and the polyamide has higher strength.

[0015] Preferably, in step (1), the structural formula of the salt-forming polyether amine is NH2-(OCH2CH2) z -NH2, and the number average molecular weight is 100-500 Da.

[0016] The team of the present application found that when a salt-forming polyether amine with a smaller molecular weight is used, the salt formation of the polyether amine and the flame retardant is easier to carry out, and the effect of improving the dispersion of the flame retardant is better, based on which the number average molecular weight of the salt-forming polyether amine in the present application is preferably 100-500 Da.

[0017] Preferably, in step (1), the flame retardant with a carboxyl group includes 2-carboxyethyl phenyl phosphinic acid (CEPPA) and / or [(6-oxo-(6H)-dibenzo-(CE)(1,2)-oxaphosphorin-6-keto) methyl]-butanedioic acid (DDP).

[0018] Preferably, in step (2), the polyamide monomer is a monomer of PA56, a monomer of PA66, a monomer of PA610, a monomer of PA612 or a monomer of PA1010.

[0019] Preferably, the preparation method specifically comprises the following steps:

[0020] (1) mixing a flame retardant with carboxyl, a salt-forming polyether amine and water, and then reacting at 50-100℃ for 1-2h, and concentrating the obtained salt solution to prepare a flame retardant salt solution;

[0021] (2) mixing a diacid, a diamine, a moisture absorption-modifying polyether amine, a catalyst and water, and then reacting at 80-100℃ for 0.5-1h, and then adding the flame retardant salt solution, and then raising the temperature to 220-240℃ for 1-2h, and then raising the temperature to 260-280℃ for 2-4h to obtain a moisture absorption flame retardant polyamide.

[0022] Preferably, in step (1), the molar ratio of the flame retardant with carboxyl to the salt-forming polyether amine is 1:1-1.05.

[0023] The molar amount of the salt-forming polyether amine is calculated according to the mass divided by the number average molecular weight.

[0024] Preferably, in step (2), the molar ratio of the diacid, the diamine and the moisture absorption-modifying polyether amine is 1:0.2-1:0.1-0.9.

[0025] Preferably, in step (1), the concentration of the flame retardant salt in the flame retardant salt solution is 70-90wt%; and in step (2), the ratio of the mass of the flame retardant salt solution to the total mass of the diacid and the diamine is 3-15:100.

[0026] Preferably, in step (2), the catalyst comprises a metal hypophosphite and / or a weak acid compound. The metal hypophosphite can be selected from sodium hypophosphite and / or potassium hypophosphite; and the weak acid compound can be selected from phosphoric acid and / or boric acid.

[0027] Preferably, in step (2), the ratio of the total mass of the diacid and the diamine, the mass of the catalyst and the mass of water is 100:0.1-1:10-40.

[0028] Preferably, in step (2), the antioxidant is added when mixing the diacid, the diamine, the moisture absorption-modifying polyether amine, the catalyst and water.

[0029] Further, the antioxidant comprises one or more of antioxidant 1010, antioxidant 1098, antioxidant 1076, antioxidant 168, antioxidant SEED.

[0030] Further, in step (2), the ratio of the total mass of the diacid and the diamine to the mass of the antioxidant is 100:0.1-1.

[0031] In a second aspect, the present application provides a moisture absorption flame retardant polyamide prepared by the preparation method.

[0032] In a third aspect, the present application provides a preparation method of the moisture-absorbing and flame-retardant polyamide fiber, comprising the following steps: after the moisture-absorbing and flame-retardant polyamide is made into a chip, spinning is performed to obtain the moisture-absorbing and flame-retardant polyamide fiber.

[0033] Preferably, in the process of spinning, a profiled spinneret plate with a triangular, pentagonal, cross-shaped, star-shaped, X-shaped or Y-shaped cross section is used.

[0034] By using the profiled spinneret plate and combining with the spinning process design, the moisture in the obtained fiber can be easily adsorbed and diffused, thereby improving the moisture absorption of the fiber.

[0035] Preferably, the relative viscosity of the chip is 2.4-3.2, the melting point is 230-260℃, and the water content is less than 1000ppm.

[0036] Further, the water content of the chip is less than 400ppm.

[0037] Compared with the prior art, the present application has the following advantages:

[0038] (1) By pre-salting the flame retardant with carboxyl and the salt-forming polyether amine, and then participating in the copolymerization of the polyamide, the dispersibility of the flame retardant in the polyamide can be improved, so that the flame retardant can play a better flame-retardant effect;

[0039] (2) By using the salt-forming polyether amine and the moisture-modifying polyether amine to participate in the copolymerization of the polyamide, the polyether amine can be uniformly dispersed in the polyamide, and by using the strong moisture absorption of the polyether amine itself and the amide bond formed between the polyether amine and the polyamide monomer, the moisture absorption of the polyamide can be improved to a large extent;

[0040] (3) By using the polyether amine containing polyethylene oxide and poly-2,3-epoxybutane two segments as the moisture-modifying polyether amine, and controlling the ratio between the two segments, the moisture absorption of the polyamide can be improved to a larger extent, and the polyamide fiber has high strength;

[0041] (4) By using NH2-(OCH2CH2) x -NH2 with a specific molecular weight as the salt-forming polyether amine, the salt formation between the flame retardant and the polyether amine can be more easily carried out, thereby helping to improve the flame retardance of the polyamide. DETAILED DESCRIPTION

[0042] The present application will be further described below in conjunction with examples.

[0043] In each of the following examples, the molar mass of the polymer is calculated according to the mass divided by the number average molecular weight.

[0044] Overall example

[0045] A method for preparing a moisture-absorbing flame-retardant polyamide, comprising the following steps:

[0046] (1) salifying a flame-retardant agent with a carboxyl group with a salt-forming polyether amine to obtain a flame-retardant agent salt;

[0047] (2) copolymerizing a polyamide monomer, the flame-retardant agent salt and a moisture-modifying polyether amine to obtain a moisture-absorbing flame-retardant polyamide.

[0048] As a specific embodiment, in step (1), the structure of the salt-forming polyether amine is NH2-(OCH2CH2) z -NH2, and the number average molecular weight is 100-500 Da.

[0049] As a specific embodiment, in step (2), the moisture-modifying polyether amine has a molecular weight of 100-5000 Da, and the polyether chain is one or more of polyethylene oxide, polypropylene oxide, polybutylene oxide, a block copolymer composed of polyethylene oxide and polypropylene oxide, and a block copolymer composed of polyethylene oxide and polybutylene oxide.

[0050] As a specific embodiment, in step (2), the polyether chain in the moisture-modifying polyether amine is a block copolymer composed of polyethylene oxide and poly-2,3-epoxybutane, and the preparation method comprises the following steps: mixing ethylene glycol and potassium hydroxide, then adding ethylene oxide under the protection of inert gas, reacting at 110-120℃ and 0.2-0.3 MPa for 3-3.5 h, then adding 2,3-epoxybutane, and continuing to react at 110-120℃ and 0.2-0.3 MPa for 2-2.5 h to obtain a block polyether; and aminating the block polyether to obtain the moisture-modifying polyether amine; the molar ratio of the ethylene glycol, ethylene oxide and 2,3-epoxybutane is 1:17.8-19.0:1.7-1.9, and the amount of potassium hydroxide is 35-38 wt% of the ethylene glycol.

[0051] As a specific embodiment, in step (1), the flame-retardant agent with a carboxyl group comprises 2-carboxyethyl phenyl phosphinic acid (CEPPA) and / or [(6-oxo-(6H)-dibenz-(CE)(1,2)-oxaphosphorin-6-keto)methyl]-succinic acid (DDP).

[0052] As a specific embodiment, in step (2), the polyamide monomer is a monomer of PA56, a monomer of PA66, a monomer of PA610, a monomer of PA612 or a monomer of PA1010.

[0053] As a specific embodiment, the specific process of step (1) comprises the following steps: mixing the flame retardant with carboxyl, the salt-forming polyether amine and water, the molar ratio of the flame retardant with carboxyl and the salt-forming polyether amine being 1:1-1.05, reacting at 50-100℃ for 1-2h, concentrating the obtained salt solution to obtain a flame retardant salt solution with a concentration of 70-90wt%.

[0054] As a specific embodiment, the specific process of step (2) comprises the following steps: mixing the dibasic acid, the dibasic amine, the moisture absorption modifying polyether amine, the catalyst and water, the molar ratio of the dibasic acid, the dibasic amine and the moisture absorption modifying polyether amine being 1:0.2-1:0.1-0.9, the ratio of the total mass of the dibasic acid and the dibasic amine, the mass of the catalyst and the mass of water being 100:0.1-1:10-40, reacting at 80-100℃ for 0.5-1h, then adding the flame retardant salt solution, the ratio of the mass of the flame retardant salt solution and the total mass of the dibasic acid and the dibasic amine being 3-15:100, heating to 220-240℃ for 1-2h, and then heating to 260-280℃ for 2-4h to obtain the moisture absorption flame retardant polyamide.

[0055] In the above specific embodiment:

[0056] Optionally, in step (2), the catalyst comprises a metal hypophosphite and / or a weak acid compound. The metal hypophosphite can be selected from sodium hypophosphite and / or potassium hypophosphite; the weak acid compound can be selected from phosphoric acid and / or boric acid.

[0057] Optionally, in step (2), when mixing the dibasic acid, the dibasic amine, the moisture absorption modifying polyether amine, the catalyst and water, an antioxidant is added therein, the ratio of the total mass of the dibasic acid and the dibasic amine and the mass of the antioxidant being 100:0.1-1. The antioxidant can be selected from one or more of antioxidant 1010, antioxidant 1098, antioxidant 1076, antioxidant 168, antioxidant SEED.

[0058] The moisture absorption flame retardant polyamide prepared by the above preparation method is used to prepare a moisture absorption flame retardant polyamide fiber, and the preparation method comprises the following steps: after the moisture absorption flame retardant polyamide is made into a chip, spinning is performed to obtain the moisture absorption flame retardant polyamide fiber.

[0059] As a specific embodiment, in the process of spinning, a special-shaped spinneret plate with a triangular, pentagonal, cross-shaped, star-shaped, X-shaped or Y-shaped cross section is used.

[0060] As a specific embodiment, the relative viscosity of the chip is 2.4-3.2, the melting point is 230-260℃, and the water content is less than 1000ppm.

[0061] As a specific embodiment, the specific process of the spinning includes the following steps: melt extrusion of the chips in a twin-screw extruder, spinning by a spinning machine, spinning temperature is 250-280℃, spinning speed is 3000-5000m / min, the melt is accurately metered by a metering pump, then is sprayed out to form a melt stream through a spinneret, then is cooled and blown, is bundled and oiled, is stretched and set, the stretching multiple is 1.0-4.0 times, and is wound into a shape again.

[0062] Example 1

[0063] A moisture-absorbing and flame-retardant polyamide fiber is prepared, and the steps are as follows:

[0064] (1) Preparation of moisture-absorbing modified polyether amine:

[0065] (1.1) After the ethylene glycol and 35% of the potassium hydroxide based on the mass of the ethylene glycol are uniformly mixed in a reaction kettle, the air in the reaction kettle is replaced with nitrogen for 2 times, then heated to 100℃ for vacuum dehydration, nitrogen is introduced again, 17.8 times of the molar amount of the ethylene glycol of the ethylene oxide is added, reacted at 115℃ and 0.25MPa for 3h, then 1.9 times of the molar amount of the ethylene glycol of the 2,3-epoxybutane is added, continuously reacted at 115℃ and 0.25MPa for 2h, neutralized by adding phosphoric acid, then dehydrated, and a block polyether is prepared.

[0066] (1.2) After the block polyether and liquid ammonia with a molar ratio of 1:14 are uniformly mixed in a high-pressure reaction kettle, 8% of the Raney nickel catalyst based on the mass of the block polyether is added, the air in the kettle is removed, hydrogen is introduced to a pressure of 14MPa, and stirred at 215℃ for 3.5h, after removing the catalyst by filtration, vacuum distillation is performed, and the moisture-absorbing modified polyether amine with a number average molecular weight of 1068Da is prepared.

[0067] (2) Equal molar of DDP and polyether amine with a number average molecular weight of 200Da (the structural formula is NH2-(OCH2CH2) z -NH2) are uniformly mixed, 30% of water based on the total weight of the DDP and the polyether amine is added, and the reaction is carried out at 70℃ for 1h in a closed environment, then heated to 120℃, the salt solution is concentrated, and the salt concentration is controlled in the range of 80wt%.

[0068] (3) The molar ratio of adipic acid, pentanediamine, and moisture absorption modified polyether amine is 1:0.85:0.2, and the mass ratio of antioxidant 168, sodium hypophosphite, and water is 0.1%, 0.2%, and 20% of the total mass of adipic acid and pentanediamine, respectively. Add them to the polymerization reactor, remove the air in the reactor, and seal the reactor. Stir at 90°C for 0.5h, then add 5% of the total mass of adipic acid and pentanediamine as a flame retardant salt solution. After heating to 180°C, release the pressure to 200KPa, continue to heat to 220°C, and maintain the pressure for 1h. Then release the pressure to normal pressure, and finally continue to heat to 270°C. After 1h of reaction, perform vacuum operation and observe the change in stirring power. After about 1.5h, discharge and draw the granules, and obtain moisture absorption and flame retardant polyamide chips.

[0069] (4) The moisture absorption and flame retardant polyamide chips obtained above are melt-extruded in a twin-screw extruder, and spun using a spinning machine. The melt is accurately metered by a metering pump, then sprayed through a spinneret plate with a triangular cross-section to form a melt stream, and then cooled, blown, oiled, multi-stretched, and shaped into a roll. The spinning temperature is 270°C, the spinning speed is controlled at 3000m / min, and the stretching ratio of multi-stretching is 2.0 times. Thus, moisture absorption and flame retardant polyamide fibers are obtained.

[0070] Example 2

[0071] A moisture absorption and flame retardant polyamide fiber is prepared by the following steps:

[0072] (1) Preparation of moisture absorption modified polyether amine:

[0073] (1.1) Mix ethylene glycol and 35% of the mass of ethylene glycol as potassium hydroxide in the reaction kettle, replace the air in the reaction kettle with nitrogen for 2 times, then heat to 100°C and vacuum to remove water, then introduce nitrogen, and add 18 times the molar amount of ethylene glycol as ethylene oxide. React at 110°C and 0.2MPa for 3.5h, then add 1.8 times the molar amount of 2,3-epoxybutane as 2,3-epoxybutane, and continue to react at 110°C and 0.2MPa for 2.5h. Add phosphoric acid for neutralization, then dehydrate to obtain a block polyether.

[0074] (1.2) Mix the block polyether and liquid ammonia in a high-pressure reaction kettle at a molar ratio of 1:14, then add 8% of the mass of the block polyether as Raney nickel catalyst, remove the air in the kettle, introduce hydrogen gas to a pressure of 14MPa, and stir at 215°C for 3.5h. After filtering to remove the catalyst, perform vacuum distillation to obtain moisture absorption modified polyether amine with a number average molecular weight of 1259Da.

[0075] (2) Mix equal molar amounts of DDP and polyether amine with a number average molecular weight of 500Da (structural formula: NH2-(OCH2CH2)z - NH2) was mixed evenly, and 20% of water based on the total weight of DDP and polyetheramine was added. The temperature was controlled at 70°C in a closed environment for 1 h, and then the temperature was increased to 120°C. The concentration of the salt solution was controlled in the range of 80 wt%.

[0076] (3) The molar ratio of adipic acid, pentanediamine, and moisture absorption modified polyetheramine was 1:0.65:0.4, and the mass ratio of antioxidant 1098, sodium hypophosphite, and water was 0.2%, 0.3%, and 20% of the total mass of adipic acid and pentanediamine, respectively. The above-mentioned substances were added to the polymerization reactor. The air in the reactor was removed, and the reactor was closed. After stirring at 80°C for 0.5 h, 7% of the flame retardant salt solution based on the total mass of adipic acid and pentanediamine was added. After increasing the temperature to 180°C, the pressure was released to 300 KPa, and the temperature was further increased to 220°C. After maintaining the pressure for 1 h, the pressure was released to normal pressure. Finally, the temperature was continuously increased to 270°C, and the reaction was carried out for 1 h. Vacuum was then applied, and the change in stirring power was observed. After about 1.5 h, nitrogen was introduced, and the product was discharged and drawn into strands for granulation. Moisture absorption and flame retardant polyamide chips were obtained.

[0077] (4) The moisture absorption and flame retardant polyamide chips obtained above were melt-extruded in a twin-screw extruder, and spun using a spinning machine. The melt was accurately metered by a metering pump and then sprayed through a spinneret plate with an X-shaped cross-section to form a melt stream. The melt stream was then cooled, blown, oiled, multi-stretched, and shaped into a roll, wherein the spinning temperature was 270°C, the spinning speed was controlled at 3000 m / min, and the stretching ratio of multi-stretching was 2.0 times. Moisture absorption and flame retardant polyamide fibers were obtained.

[0078] Example 3

[0079] A moisture absorption and flame retardant polyamide fiber was prepared according to the following steps:

[0080] (1) Preparation of moisture absorption modified polyetheramine:

[0081] (1.1) Ethylene glycol and 38% of potassium hydroxide based on the mass of ethylene glycol were mixed evenly in a reaction kettle. The air in the reaction kettle was replaced with nitrogen for 2 times, and then heated to 100°C to remove water. Nitrogen was introduced, and 19 times the molar amount of ethylene oxide based on the mass of ethylene glycol was added. The reaction was carried out at 120°C and 0.3 MPa for 3 h. Then, 1.7 times the molar amount of 2,3-epoxybutane based on the mass of ethylene glycol was added, and the reaction was continued at 120°C and 0.3 MPa for 2 h. Phosphoric acid was added for neutralization, and then dehydrated to obtain a block polyether.

[0082] (1.2) The block polyether and liquid ammonia with a molar ratio of 1:14 were mixed uniformly in a high-pressure reaction kettle, 8% of the block polyether mass was added as Raney nickel catalyst, the air in the kettle was removed, hydrogen was introduced to a pressure of 14 MPa, and stirring was carried out at 215°C for 3.5h. After filtering out the catalyst, vacuum distillation was carried out to obtain a hygroscopic modified polyether amine with a number average molecular weight of 1307 Da.

[0083] (2) Equal molar amounts of DDP and polyether amine with a number average molecular weight of 100 Da (structural formula NH2-(OCH2CH2) z -NH2) were mixed uniformly, 20% of the total weight of DDP and polyether amine was added as water, and the temperature was controlled at 80°C in a closed environment for 1h, then the temperature was raised to 120°C, and the salt solution was concentrated to control the salt concentration in the range of 90wt%.

[0084] (3) The molar ratio of adipic acid, pentanediamine, and hygroscopic modified polyether amine was 1:0.55:0.5, and the mass of antioxidant 1010, boric acid, and water was 0.2%, 0.4%, and 30% of the total mass of adipic acid and pentanediamine, respectively, which were added to the polymerization kettle. The air in the kettle was removed, the kettle was closed, and stirring was carried out at 80°C for 1h. Then, 10% of the total mass of adipic acid and pentanediamine was added as a flame retardant salt solution. The temperature was raised to 190°C, the pressure was released to 300KPa, the temperature was further raised to 230°C, and the pressure was maintained for 1h before being released to normal pressure. Finally, the temperature was further raised to 260°C, and the reaction was carried out for 1h before vacuumizing. The stirring power was observed, and after about 1.5h, nitrogen was charged for discharge and drawing, and the hygroscopic flame-retardant polyamide chips were obtained.

[0085] (4) The hygroscopic flame-retardant polyamide chips obtained above were melt-extruded in a twin-screw extruder, and spun using a spinning machine. The melt was accurately metered by a metering pump, then sprayed through a spinneret plate with a star-shaped cross-section to form a melt stream, and then cooled, blown, oiled, multi-stretched, and shaped into a roll, wherein the spinning temperature was 260°C, the spinning speed was controlled at 3200m / min, and the stretching multiple of multi-stretching was 1.5 times. Thus, the hygroscopic flame-retardant polyamide fiber was obtained.

[0086] Comparative Example 1

[0087] A polyamide fiber was prepared by a conventional method, and the specific steps were as follows:

[0088] (1) The molar ratio of adipic acid and pentanediamine is 1:1.05, the mass ratio of antioxidant 168, sodium hypophosphite and water is 0.1%, 0.2%, 30% of the total mass of adipic acid and pentanediamine, respectively, and they are added into the polymerization reactor. The air in the reactor is removed, the reactor is sealed, stirred at 70°C for 0.5h, then heated to 180°C, depressurized to 300KPa, continued to heat to 220°C, and then depressurized to normal pressure after 1h pressure maintaining. Finally, continue to heat to 270°C, react for 1h, then vacuumize, observe the change of stirring power, and then charge nitrogen gas for discharging and drawing, and cut into granules to obtain polyamide chips.

[0089] (2) The polyamide chips obtained above are melt-extruded in a twin-screw extruder, and then spun by a spinning machine. The melt is accurately metered by a metering pump, then sprayed through a circular cross-section spinneret to form a melt stream, and then cooled, blown, oiled, multi-stage stretched, and shaped into a roll. The spinning temperature is 270°C, the spinning speed is controlled at 3000m / min, and the stretching multiple of multi-stage stretching is 2.0 times, so that polyamide fibers are obtained.

[0090] Comparative Example 2

[0091] A moisture-absorbing polyamide fiber is prepared, which is different from Example 1 only in that no flame retardant salt is added, and the specific steps are as follows:

[0092] (1) Preparation of moisture-absorbing modified polyether amine:

[0093] (1.1) The ethylene glycol and 35% of the mass of the ethylene glycol potassium hydroxide are mixed uniformly in the reaction kettle, and then the air in the reaction kettle is replaced with nitrogen for 2 times. Then heat to 100°C and vacuumize to remove water, then introduce nitrogen, and then add 17.8 times of the molar amount of ethylene glycol of ethylene oxide. React at 115°C and 0.25MPa for 3h, then add 1.9 times of the molar amount of 2,3-epoxybutane of ethylene glycol, and continue to react at 115°C and 0.25MPa for 2h. Add phosphoric acid for neutralization, then dehydrate, and prepare a block polyether.

[0094] (1.2) The block polyether and liquid ammonia with a molar ratio of 1:14 are mixed uniformly in a high-pressure reaction kettle, then 8% of the mass of the block polyether of Raney nickel catalyst is added, the air in the kettle is removed, hydrogen is introduced to a pressure of 14MPa, and stirred at 215°C for 3.5h. After filtering the catalyst, vacuum distillation is carried out to prepare moisture-absorbing modified polyether amine.

[0095] (2) The molar ratio of adipic acid, pentanediamine, and moisture absorption modifying polyether amine is 1:0.85:0.2, and the mass ratio of antioxidant 168, sodium hypophosphite, and water is 0.1%, 0.2%, and 20% of the total mass of adipic acid and pentanediamine, respectively, which are added into the polymerization reactor. The air in the reactor is removed, and the reactor is sealed. After stirring at 90°C for 0.5h, the temperature is raised to 180°C, and then the pressure is released to 200KPa. The temperature is continuously raised to 220°C, and the pressure is maintained for 1h before being released to normal pressure. Finally, the temperature is continuously raised to 270°C, and the reaction is carried out for 1h. Vacuum operation is then performed, and the stirring power is observed. After about 1.5h, nitrogen is charged, and the product is discharged and drawn into strands for pelletizing to obtain moisture absorption and flame retardant polyamide chips.

[0096] (3) The moisture absorption and flame retardant polyamide chips obtained above are melt-extruded in a twin-screw extruder, and then spun using a spinning machine. The melt is accurately metered by a metering pump and then sprayed through a spinneret plate with a triangular cross-section to form a melt stream. The melt stream is then cooled, blown, oiled, multi-stretched, and shaped into a roll, with a spinning temperature of 270°C and a spinning speed of 3000m / min. The multi-stretching ratio is 2.0, resulting in moisture absorption and flame retardant polyamide fibers.

[0097] Comparative Example 3

[0098] A flame-retardant polyamide fiber is prepared, which is different from Example 1 only in that no moisture absorption modifying polyether amine is added in step (2). The specific steps are as follows:

[0099] (1) Equal molar amounts of DDP and polyether amine with a number average molecular weight of 200Da (structural formula NH2-(OCH2CH2) x -NH2) are mixed uniformly, and 30% of water based on the total weight of DDP and polyether amine is added. The temperature is controlled at 70°C in a sealed environment for 1h, and then the temperature is raised to 120°C for salt solution concentration, with a salt concentration of 80wt%.

[0100] (2) The molar ratio of adipic acid and pentanediamine is 1:1.05, and the mass ratio of antioxidant 168, sodium hypophosphite, and water is 0.1%, 0.2%, and 20% of the total mass of adipic acid and pentanediamine, respectively, which are added into the polymerization reactor. The air in the reactor is removed, and the reactor is sealed. After stirring at 90°C for 0.5h, 5% of the flame retardant salt solution based on the total mass of adipic acid and pentanediamine is added. The temperature is raised to 180°C, and then the pressure is released to 200KPa. The temperature is continuously raised to 220°C, and the pressure is maintained for 1h before being released to normal pressure. Finally, the temperature is continuously raised to 270°C, and the reaction is carried out for 1h. Vacuum operation is then performed, and the stirring power is observed. After about 1.5h, nitrogen is charged, and the product is discharged and drawn into strands for pelletizing to obtain moisture absorption and flame retardant polyamide chips.

[0101] (3) melt-extruding the moisture-absorbing and flame-retardant polyamide chips obtained above in a twin-screw extruder, spinning by using a spinning machine, accurately metering the melt by using a metering pump, and then spraying the melt through a spinneret plate with a triangular cross-section of the spinneret holes to form a melt stream, and then cooling and blowing, oiling, multi-stage drawing and setting, and winding to form a fiber, wherein the spinning temperature is 270°C, the spinning speed is controlled at 3000 m / min, and the drawing ratio of the multi-stage drawing and setting is 2.0 times, thereby obtaining a moisture-absorbing and flame-retardant polyamide fiber.

[0102] Example 4

[0103] A moisture-absorbing and flame-retardant polyamide fiber was prepared, which was only different from Example 2 in that the polyether amine used in step (1) had a number average molecular weight of 1000 Da, and the specific steps were as follows:

[0104] A moisture-absorbing and flame-retardant polyamide fiber was prepared, and the steps were as follows:

[0105] (1) preparing a polyether amine for moisture absorption modification:

[0106] (1.1) mixing ethylene glycol and 35% of potassium hydroxide based on the mass of the ethylene glycol in a reaction kettle, replacing the air in the reaction kettle with nitrogen for 2 times, then heating to 100°C to remove water, and then introducing nitrogen, adding 18 times of molar amount of ethylene oxide based on the molar amount of the ethylene glycol, and then reacting at 110°C and 0.2 MPa for 3.5 h, and then adding 1.8 times of molar amount of 2,3-epoxybutane based on the molar amount of the ethylene glycol, and then continuing to react at 110°C and 0.2 MPa for 2.5 h, and then adding phosphoric acid for neutralization, and then removing water, thereby preparing a block polyether.

[0107] (1.2) mixing the block polyether and liquid ammonia in a high-pressure reaction kettle at a molar ratio of 1:14, adding 8% of Raney nickel catalyst based on the mass of the block polyether, removing the air in the kettle, introducing hydrogen to a pressure of 14 MPa, and then stirring and reacting at 215°C for 3.5 h, and then removing the catalyst by filtration, and then performing vacuum distillation, thereby preparing a polyether amine for moisture absorption modification.

[0108] (2) mixing equal molar amounts of DDP and a polyether amine having a number average molecular weight of 1000 Da (the structural formula is NH2-(OCH2CH2) z -NH2) uniformly, adding 20% of water based on the total weight of the DDP and the polyether amine, and then reacting at 70°C for 1 h in a sealed environment, and then increasing the temperature to 120°C to concentrate the salt solution, and then controlling the salt concentration in the range of 80 wt%.

[0109] (3) The molar ratio of adipic acid, pentanediamine, and moisture absorption modification polyether amine is 1:0.65:0.4, and the mass ratio of antioxidant 1098, sodium hypophosphite, and water is 0.2%, 0.3%, and 20% of the total mass of adipic acid and pentanediamine, respectively, which is added to the polymerization reactor. Remove the air in the reactor, seal the reactor, and stir at 80°C for 0.5h. Then add 7% of the total mass of adipic acid and pentanediamine as a flame retardant salt solution. After heating to 180°C, release 300KPa pressure, continue to heat to 220°C, and maintain pressure for 1h. Then release the pressure to normal pressure, and finally continue to heat to 270°C. After 1h of reaction, vacuum operation is performed, and the stirring power is observed. After about 1.5h, nitrogen is charged and discharged, and the strip is cut into particles to obtain moisture absorption and flame retardant polyamide chips.

[0110] (4) The moisture absorption and flame retardant polyamide chips obtained above are melt-extruded in a double screw extruder, and spun using a spinning machine. The melt is accurately metered by a metering pump, then sprayed through a spinneret with an X-shaped cross-section to form a melt stream, and then cooled, blown, oiled, multi-stretched, and shaped into a roll. The spinning temperature is 270°C, the spinning speed is controlled at 3000m / min, and the stretching ratio of multi-stretching is 2.0 times, thereby obtaining moisture absorption and flame retardant polyamide fibers.

[0111] Example 5

[0112] A moisture absorption and flame retardant polyamide fiber is prepared, which is different from Example 1 only in that the moisture absorption modification polyether amine used in step (2) has a structural formula of NH2-(OCH2CH2) x -NH2 (i.e., the polyether chain is polyethylene oxide), and the specific steps are as follows:

[0113] (1) Mix equal molar amounts of DDP and polyether amine with a number average molecular weight of 200Da (structural formula NH2-(OCH2CH2) z -NH2) uniformly, and add 30% of the total weight of DDP and polyether amine as water. Control the temperature at 70°C in a sealed environment for 1h, then heat to 120°C, and concentrate the salt solution to control the salt concentration in the range of 80wt%.

[0114] (2) Adipic acid, pentanediamine, and 1000Da polyether amine (structural formula NH2-(OCH2CH2) xThe molar ratio of the three is 1:0.85:0.2, the mass ratio of the antioxidant 168, sodium hypophosphite, and water is 0.1%, 0.2%, and 20% of the total mass of adipic acid and pentanediamine, respectively, which is added into the polymerization reactor, the air in the reactor is removed, the reactor is sealed, and stirred at 90°C for 0.5h, then 5% of the total mass of adipic acid and pentanediamine is added as a flame retardant salt solution; after heating to 180°C, the pressure is released to 200KPa, and the temperature is further increased to 220°C, and the pressure is maintained for 1h, then the pressure is released to normal pressure, and finally the temperature is further increased to 270°C, and the reaction is carried out for 1h, then vacuum is applied, the stirring power is observed, and after about 1.5h, nitrogen is charged and discharged, and the strip is cut into particles, to obtain a moisture-absorbing flame-retardant polyamide chip.

[0115] (3) The moisture-absorbing flame-retardant polyamide chip obtained above is melt-extruded in a double-screw extruder, and spun by a spinning machine, the melt is accurately metered by a metering pump, then sprayed through a spinneret plate with a triangular cross-section to form a melt stream, then cooled and blown, gathered and oiled, multi-stage stretched and shaped, and wound into a shape, wherein the spinning temperature is 270°C, the spinning speed is controlled at 3000m / min, and the stretching multiple of the multi-stage stretching and shaping is 2.0 times, to obtain a moisture-absorbing flame-retardant polyamide fiber.

[0116] Example 6

[0117] A moisture-absorbing flame-retardant polyamide fiber is prepared, which is different from Example 1 only in that the moisture-absorbing modification polyetheramine structural formula used in step (2) is NH2-(OCH(CH3)CH(CH3)) y -NH2 (i.e., the polyether chain is poly-2,3-epoxybutane), and the specific steps are as follows:

[0118] (1) Equal molar amounts of DDP and polyetheramine with a number average molecular weight of 200Da (structural formula NH2-(OCH2CH2) z -NH2) are mixed uniformly, and 30% of the total weight of DDP and polyetheramine is added as water, and the temperature is controlled at 70°C in a sealed environment for 1h, then the temperature is increased to 120°C, the salt solution is concentrated, and the salt concentration is controlled in the range of 80wt%.

[0119] (2) Adipic acid, pentanediamine, and 1000Da polyetheramine (structural formula NH2-(OCH(CH3)CH(CH3) yThe molar ratio of the three is 1:0.85:0.2, the mass ratio of antioxidant 168, sodium hypophosphite, and water is 0.1%, 0.2%, and 20% of the total mass of adipic acid and pentanediamine, respectively, and they are added into the polymerization reactor. After the air in the reactor is removed, the reactor is sealed and stirred at 90°C for 0.5h. Then, 5% of the total mass of adipic acid and pentanediamine is added as a flame retardant salt solution. After the temperature is raised to 180°C, the pressure is released to 200KPa, and the temperature is further raised to 220°C. After 1h of pressure maintenance, the pressure is released to normal pressure. Finally, the temperature is continuously raised to 270°C, and the reaction is carried out for 1h. Then, vacuum operation is performed, and the stirring power is observed. After about 1.5h, nitrogen is filled, and the material is discharged and drawn into strands for granulation, obtaining moisture-absorbing and flame-retardant polyamide chips.

[0120] (3) The moisture-absorbing and flame-retardant polyamide chips obtained above are melt-extruded in a double-screw extruder, and spun using a spinning machine. The melt is accurately metered by a metering pump, and then sprayed through a spinneret plate with a triangular cross-section to form a melt stream. Then, the melt stream is cooled, blown, oiled, multi-stretched, and shaped into a roll, with a spinning temperature of 270°C and a spinning speed of 3000m / min. The stretching ratio of the multi-stretching shaping is 2.0, obtaining moisture-absorbing and flame-retardant polyamide fibers.

[0121] Example 7

[0122] A moisture-absorbing and flame-retardant polyamide fiber is prepared, which is different from Example 1 only in that the moisture-absorbing modified polyether amine used in step (2) has an increased content of polyethylene oxide segments and a decreased content of poly-2,3-epoxybutane segments. The specific steps are as follows:

[0123] (1) Preparation of moisture-absorbing modified polyether amine:

[0124] (1.1) Ethylene glycol and 35% of the mass of ethylene glycol, i.e., potassium hydroxide, are mixed uniformly in a reaction kettle. The air in the reaction kettle is replaced with nitrogen for 2 times, and then heated to 100°C for dehydration under vacuum. Nitrogen is introduced, and 19.2 times the molar amount of ethylene glycol, i.e., ethylene oxide, is added. The reaction is carried out at 115°C and 0.25MPa for 3.5h. Then, 0.5 times the molar amount of ethylene glycol, i.e., 2,3-epoxybutane, is added, and the reaction is continued at 115°C and 0.25MPa for 1.5h. Phosphoric acid is added for neutralization, and then dehydrated to obtain a block polyether.

[0125] (1.2) The block polyether and liquid ammonia with a molar ratio of 1:14 are mixed uniformly in a high-pressure reaction kettle. Then, 8% of the mass of the block polyether, i.e., Raney nickel catalyst, is added. The air in the kettle is removed, and hydrogen is introduced to a pressure of 14MPa. The reaction is carried out at 215°C for 3.5h. After filtering to remove the catalyst, vacuum distillation is performed to obtain the moisture-absorbing modified polyether amine with a number average molecular weight of 1090Da.

[0126] (2) Mix equal molar amounts of DDP with polyether amine (structure formula: NH2-(OCH2CH2) z -NH2) having a number average molecular weight of 200 Da, and add 30% water based on the total weight of DDP and polyether amine, control the temperature at 70°C in a closed environment for 1 h, then increase the temperature to 120°C, and perform concentration of the salt solution, control the salt concentration in the range of 80 wt%.

[0127] (3) Add adipic acid, pentanediamine, and hygroscopic modification polyether amine in a molar ratio of 1:0.85:0.2, and antioxidants 168, sodium hypophosphite, and water in a mass ratio of 0.1%, 0.2%, and 20% of the total mass of adipic acid and pentanediamine, respectively, into a polymerization reactor, remove air in the reactor, and seal the reactor. Stir at 90°C for 0.5 h, then add 5% of the flame retardant salt solution based on the total mass of adipic acid and pentanediamine. Increase the temperature to 180°C, then depressurize to 200 KPa, continue to increase the temperature to 220°C, maintain the pressure for 1 h, then depressurize to normal pressure, finally continue to increase the temperature to 270°C, and react for 1 h. Perform vacuum extraction, observe the change in stirring power, and after about 1.5 h, discharge and draw the product into strands, and cut the strands to obtain hygroscopic flame-retardant polyamide chips.

[0128] (4) Melt-extrude the hygroscopic flame-retardant polyamide chips obtained above in a double-screw extruder, and spin the chips using a spinning machine. Accurately meter the melt using a metering pump, then spray the melt through a spinneret plate with a triangular cross-section to form a melt stream, then cool and blow, bundle, oil, multi-stage stretch, and set, and finally wind to form a fiber. The spinning temperature is 270°C, the spinning speed is controlled at 3000 m / min, and the multi-stage stretch set is 2.0 times, thereby obtaining a hygroscopic flame-retardant polyamide fiber.

[0129] Example 8

[0130] Prepare a hygroscopic flame-retardant polyamide fiber, which is different from Example 1 only in that the content of polyethylene oxide segments in the hygroscopic modification polyether amine used in step (2) is reduced, and the content of poly-2,3-epoxybutane segments is increased. The specific steps are as follows:

[0131] (1) Prepare a hygroscopic modification polyether amine:

[0132] (1.1) Mix ethylene glycol and 35% potassium hydroxide based on the mass of ethylene glycol in a reactor, replace the air in the reactor with nitrogen for 2 times, then heat to 100°C to remove water, introduce nitrogen again, add 12.8 times the molar amount of ethylene oxide based on the molar amount of ethylene glycol, and react at 115°C and 0.25 MPa for 160 min. Then add 6.9 times the molar amount of 2,3-epoxybutane based on the molar amount of ethylene glycol, and continue to react at 115°C and 0.25 MPa for 3 h. Add phosphoric acid for neutralization, then remove water, and obtain a block polyether.

[0133] (1.2) The block polyether and liquid ammonia with a molar ratio of 1:14 were mixed uniformly in a high-pressure reaction kettle, then 8% of the block polyether mass was added as Raney nickel catalyst, the air in the kettle was removed, hydrogen was introduced to a pressure of 14 MPa, and stirring was carried out at 215°C for 3.5 h. After removing the catalyst by filtration, vacuum distillation was carried out to obtain a hygroscopic modified polyether amine with a number average molecular weight of 1107 Da.

[0134] (2) Equal molar amounts of DDP and a polyether amine with a number average molecular weight of 200 Da (structural formula: NH2-(OCH2CH2) z -NH2) were mixed uniformly, and 30% of the total weight of DDP and polyether amine was added as water. The reaction was carried out at 70°C for 1 h in a closed environment, then the temperature was increased to 120°C, and the salt solution was concentrated to control the salt concentration in the range of 80 wt%.

[0135] (3) The molar ratio of adipic acid, pentanediamine, and hygroscopic modified polyether amine was 1:0.85:0.2, and the mass ratio of antioxidant 168, sodium hypophosphite, and water was 0.1%, 0.2%, and 20% of the total mass of adipic acid and pentanediamine, respectively. They were added to the polymerization kettle, the air in the kettle was removed, and the kettle was sealed. After stirring at 90°C for 0.5 h, 5% of the total mass of adipic acid and pentanediamine was added as a flame retardant salt solution. After heating to 180°C, the pressure was released to 200 KPa, and the temperature was further increased to 220°C. After holding the pressure for 1 h, the pressure was released to normal pressure, and finally the temperature was increased to 270°C. After 1 h of reaction, vacuum was applied, the stirring power was observed, and after about 1.5 h, nitrogen was introduced for discharge and strand cutting to obtain hygroscopic flame-retardant polyamide chips.

[0136] (4) The hygroscopic flame-retardant polyamide chips obtained above were melt-extruded in a twin-screw extruder, and spun using a spinning machine. The melt was accurately metered by a metering pump, then sprayed through a spinneret plate with a triangular cross-section to form a melt stream, then cooled and blown, bundled and oiled, multi-stage stretched and shaped, and wound into a shape. The spinning temperature was 270°C, the spinning speed was controlled at 3000 m / min, and the multi-stage stretching ratio was 2.0 times to obtain hygroscopic flame-retardant polyamide fibers.

[0137] Test Example

[0138] The polyamide fibers obtained in Examples 1-8 and Comparative Examples 1-3 were tested for breaking strength, moisture regain, and limiting oxygen index (LOI), and the relevant test results are shown in Table 1.

[0139] Table 1

[0140] Breaking strength / cN / dtex Moisture regain / % LOI / % Example 1 3.9 6.5 32 Example 2 3.6 8.1 34 Example 3 3.2 9.0 37 Comparative Example 1 4.5 5.3 25 Comparative Example 2 4.1 6.0 27 Comparative Example 3 4.2 5.8 30 Example 4 3.5 7.9 31 Example 5 3.2 6.1 32 Example 6 3.8 5.9 32 Example 7 3.5 6.2 31 Example 8 3.9 6.0 32

[0141] From Table 1, it can be seen that:

[0142] (1) The polyamide fibers prepared in Examples 1-3 all have good moisture absorption, and also have good flame retardant properties. Due to the different contents of polyether amine and flame retardant in the chips in Examples 1-3, the properties of the prepared fibers are different. Among them, the polyether amine and flame retardant content in Example 3 is higher, so the overall moisture regain and limiting oxygen index of the fiber is higher. Compared with Example 1, Comparative Example 1 is PA56 fiber, it can be seen that the moisture regain and LOI of PA56 fiber are both lower, mainly because the flame retardant groups and good moisture absorption groups are not introduced into the molecular chain of PA56; the chips used in Comparative Example 2 do not contain flame retardant components, but due to the introduction of polyether amine moisture absorption component, the flame retardant effect of the fiber is poor, and its moisture regain is slightly lower than that of Example 1; the chips used in Comparative Example 3 do not contain the subsequent introduction of polyether amine, but the flame retardant component and a small amount of polyether amine component are introduced in the early stage, resulting in that the moisture regain and flame retardant property of the fiber are both slightly lower than those of Example 1. It can be seen from the data in Table 1 that by introducing flame retardant and polyether amine moisture absorption components into the polyamide molecular chain, and then designing the spinning structure, moisture absorption and flame retardant polyamide fibers can be obtained.

[0143] (2) The molecular weight of the polyether amine used to form a salt with the flame retardant in Example 4 is too large, and the limiting oxygen index of the obtained polyamide fiber is lower than that of Example 2. This is because the polyether amine with smaller molecular weight is more easily salified with the flame retardant, thereby improving the dispersibility of the flame retardant in the polyamide, so that it can improve the flame retardancy of the polyamide fiber to a greater extent.

[0144] (3) The polyether amine introduced in step (2) of Example 1 contains both polyethylene oxide and poly-2,3-epoxybutane segments, while Examples 5 and 6 only contain polyethylene oxide or poly-2,3-epoxybutane segments, respectively. The moisture absorption of the polyether amine fibers obtained is lower than that of Example 1. This is because the polyethylene oxide segment has high hydrophilicity, and the poly-2,3-epoxybutane segment can better reduce the crystallinity of the polyamide. The two segments cooperate with each other to a greater extent to promote the absorption and diffusion of water in the polyamide, thereby improving the moisture absorption of the polyamide.

[0145] (4) Compared with Example 1, the moisture absorption modified polyether amine used in Example 7 has a higher content of polyethylene oxide segment and a lower content of poly-2,3-epoxybutane segment, and the obtained polyamide fiber has a lower breaking strength, because when the content of polyethylene oxide segment in the moisture absorption modified polyether amine is too high, the system will be sticky and unstable during the spinning process, thereby causing the fiber to have a lower strength. The moisture absorption modified polyether amine used in Example 8 has a lower content of polyethylene oxide segment and a higher content of poly-2,3-epoxybutane segment, and the obtained polyamide fiber has poor moisture absorption, because when the content of poly-2,3-epoxybutane segment in the moisture absorption modified polyether amine is too high, the hydrophilicity of the polyether amine will be reduced to some extent.

[0146] The raw materials and equipment used in the present application are conventional raw materials and equipment in the art unless otherwise specified; the methods used in the present application are conventional methods in the art unless otherwise specified.

[0147] The above is only a preferred embodiment of the present application, and does not limit the present application in any way, and any simple modification, change and equivalent transformation of the above embodiment according to the technical essence of the present application still falls within the protection scope of the technical solution of the present application.

Claims

1. A method for preparing a moisture-absorbing and flame-retardant polyamide, characterized in that, Includes the following steps: (1) A flame retardant with a carboxyl group is salted with a polyetheramine used for salt formation to obtain a flame retardant salt; (2) Polyamide monomer, flame retardant salt and moisture-modifying polyetheramine are copolymerized to obtain moisture-absorbing flame-retardant polyamide; the polyether chain in the moisture-modifying polyetheramine is a block copolymer composed of polyethylene oxide and poly2,3-epoxybutane, which is polymerized from ethylene glycol, ethylene oxide and 2,3-epoxybutane in a molar ratio of 1:17.8-19.0:1.7-1.

9.

2. The preparation method according to claim 1, characterized in that, In step (2), the molecular weight of the hygroscopic modified polyetheramine is 100-5000 Da.

3. The preparation method according to claim 1, characterized in that, In step (2), the preparation method of the moisture-modifying polyetheramine includes the following steps: ethylene glycol and potassium hydroxide are mixed, and ethylene oxide is added under inert gas protection. After reacting at 110-120℃ and 0.2-0.3 MPa for 3-3.5 h, 2,3-epoxybutane is added, and the reaction is continued at 110-120℃ and 0.2-0.3 MPa for 2-2.5 h to obtain block polyether; the block polyether is amination to obtain the moisture-modifying polyetheramine; the amount of potassium hydroxide used is 35-38 wt% of ethylene glycol.

4. The preparation method according to claim 1, characterized in that, In step (1), the polyetheramine used for salt formation has the structural formula NH2-(OCH2CH2). z -NH2, with a number-average molecular weight of 100-500 Da.

5. The preparation method according to claim 1, characterized in that, Specifically, the following steps are included: (1) After mixing the flame retardant with carboxyl groups, the salt-forming polyetheramine and water, react at 50-100℃ for 1-2 h, and concentrate the obtained salt solution to obtain the flame retardant salt solution. (2) Mix the dicarboxylic acid, diamine, hygroscopic modified polyetheramine, catalyst and water, and react at 80-100℃ for 0.5-1 h. Then add flame retardant salt solution, heat to 220-240℃ and react for 1-2 h, then heat to 260-280℃ and react for 2-4 h to obtain hygroscopic flame retardant polyamide.

6. The preparation method according to claim 5, characterized in that, In step (2), the molar ratio of the dicarboxylic acid, diamine and hygroscopic modified polyetheramine is 1:0.2-1:0.1-0.

9.

7. The preparation method according to claim 5, characterized in that, In step (1), the concentration of flame retardant salt in the flame retardant salt solution is 70-90 wt%; in step (2), the mass ratio of the flame retardant salt solution to the total mass of the dicarboxylic acid and diamine is 3-15:

100.

8. A moisture-absorbing and flame-retardant polyamide, characterized in that, The moisture-absorbing and flame-retardant polyamide is prepared by the preparation method described in any one of claims 1-7.

9. A method for preparing moisture-absorbing and flame-retardant polyamide fibers, characterized in that, Includes the following steps: After the moisture-absorbing and flame-retardant polyamide as described in claim 8 is made into slices, it is spun to obtain moisture-absorbing and flame-retardant polyamide fibers.

10. The preparation method according to claim 9, characterized in that, During the spinning process, irregularly shaped spinnerets with spinneret orifice cross sections of triangle, pentagon, cross, star, X, or Y are used.