Polyamide fiber with cool feeling and flame retardant property and preparation method thereof

Abstract

The preparation method specifically comprises the following steps: adding pyridine heterocyclic ring-containing amide salt, aromatic structure amide salt, a molecular weight regulator and deionized water into a high-pressure polymerization kettle to serve as a reaction system; regulating and controlling the temperature and the pressure of a reaction system in an inert gas atmosphere, and carrying out staged reaction to obtain the combined flame retardant; the preparation method comprises the following steps: premixing a combined flame retardant, polyamide resin and a cool-feeling compound additive, and carrying out melt blending to obtain the polyamide chip with the cool-feeling and flame-retardant functions, wherein the cool-feeling compound additive comprises at least two cool-feeling assistants with different particle sizes; the polyamide chips with the cool feeling and flame retardant functions are subjected to melt spinning, and the polyamide fiber with the cool feeling and flame retardant performance is obtained and successfully achieves the cool feeling effect and the flame retardant performance on the basis that the inherent high strength of the polyamide fiber is kept; the method is suitable for manufacturing outdoor sun-proof clothes, high-end sports underwear, special occupational tool linings and the like.

Description

Technical Field

[0001] This invention relates to the field of polyamide fibers, and in particular to a polyamide fiber with both cooling and flame-retardant properties and its preparation method. Background Technology

[0002] With economic development and consumption upgrading, people have placed higher demands on the functionality, comfort, and environmental friendliness of clothing fabrics. During hot seasons, textiles with continuous cooling and moisture-wicking properties are favored by the market. Polyamide fibers, especially the dominant polyamide 6 and polyamide 66, are ideal substrates for developing cooling fabrics due to their excellent mechanical strength, abrasion resistance, toughness, and good moisture absorption.

[0003] Currently, the most common cooling fibers on the market are made by adding highly thermally conductive inorganic powders, such as jade powder and mica powder, during the spinning process. However, this method has limitations: firstly, the cooling effect of the above fibers is difficult to maintain; secondly, increasing the amount of powder added to enhance the cooling effect will seriously damage the spinnability and mechanical properties of the fibers. More importantly, the particle size of conventional powders is relatively large, which makes them prone to poor wetting with the polymer matrix during melt blending, forming micropores or air layers at the interface. Due to the extremely poor thermal conductivity of air, these defects not only fail to improve thermal conductivity but also weaken the cooling performance and cause problems such as yarn breakage during spinning. In recent years, although high thermal conductivity nanofillers such as boron nitride and aluminum nitride have shown potential, their high surface energy and easy agglomeration characteristics make it difficult to disperse evenly in actual processing, losing the advantages of the nanoscale and limiting the maximization of cooling performance. At the same time, as application scenarios expand to outdoor sports, special workwear and other fields, the market has also put forward additional requirements for flame retardant safety for fiber materials. Polyamide materials are inherently flammable, and traditional flame-retardant modification methods usually require the introduction of a large amount of flame retardant. This will undoubtedly "compete" with the powders required for cooling functionalization, which can easily lead to an excessive total amount of additives, severely deteriorating melt flowability, spinnability, and the mechanical properties of the finished fiber. Summary of the Invention

[0004] The purpose of this invention is to provide a polyamide fiber with both cooling and flame-retardant properties and its preparation method. The invention introduces two cooling additives with different particle sizes to synergistically improve the cooling properties of the polyamide fiber, and introduces a flame retardant containing a combination of pyridine and aromatic structures to improve the flame-retardant properties of the polyamide fiber.

[0005] To achieve the above objectives, this technical solution provides a method for preparing polyamide fibers that combine cooling and flame-retardant properties, comprising the following steps: A reaction system consisting of pyridine heterocyclic amide salt, aromatic amide salt, molecular weight regulator and deionized water is added to a high-pressure polymerization reactor. The reaction system is subjected to a staged reaction under an inert gas atmosphere with controlled temperature and pressure to obtain a combined flame retardant. The combination flame retardant, polyamide resin, and cooling compound additive are premixed and then melt-blended to obtain cooling flame retardant functional polyamide chips, wherein the cooling compound additive includes at least two cooling additives with different particle sizes. Polyamide fibers with both cooling and flame-retardant properties are obtained by melt spinning of polyamide chips with cooling and flame-retardant properties.

[0006] The polyamide fiber prepared in this invention, which combines cooling and flame-retardant properties, incorporates a combined flame retardant containing pyridine and aromatic structures. The flame-retardant mechanism of this combined flame retardant is based on the synergistic mechanism of nitrogen-based flame retardancy of the pyridine heterocyclic structure and flow modification of the aromatic structure. Under high-temperature conditions, the pyridine heterocyclic structure releases nitrogen-containing free radicals to capture hydrogen and hydroxyl free radicals, thereby preventing combustion. On the other hand, the steric hindrance generated by the rigid structure of the pyridine heterocyclic and aromatic structures can improve the processing fluidity of the polyamide melt. This not only allows for the timely formation of droplets upon heating and the removal of heat from the polyamide matrix, thus blocking combustion in the condensed phase, but also allows the cooling additive particles to be better wetted by the melt, further improving the thermal conductivity of the fiber and the dispersibility of the powder.

[0007] Furthermore, this solution incorporates two cooling additives with different particle sizes in the melt-blending cooling compound. The larger-particle-size cooling additive constructs the main thermal conductivity pathways within the polyamide matrix, while the smaller-particle-size cooling additive not only fills the air layer surrounding the larger particles but also effectively fills the gaps between them, thereby increasing the effective contact between particles, resulting in a denser thermal conductivity network and improving the heat transfer rate. Moreover, due to the size complementarity effect between the two cooling additives, a dense thermal conductivity pathway can be constructed within the fiber. This allows the fiber to maintain excellent cooling properties while significantly reducing the amount of cooling compound additive used. The reduced amount of cooling compound additive maintains fiber spinnability while promoting a highly oriented distribution structure of the additive powder along the fiber axis, thus reducing adverse effects on fiber mechanical properties.

[0008] Specifically, in some embodiments, the cooling compound additive includes a first cooling aid and a second cooling aid with different particle sizes, wherein the particle size of the first cooling aid is 300-600 nm, and the particle size of the second cooling aid is 30-90 nm. As mentioned above, the first cooling aid serves as a skeleton to construct the main thermally conductive network framework inside the fiber, while the second cooling aid fills the skeleton formed by the first cooling aid to form a tightly packed structure, avoiding the problem of low thermal conductivity caused by loose packing of cooling aids with a single particle size.

[0009] In some embodiments, the molecular weight regulator is one or a combination of an organic monocarboxylic acid, an organic dicarboxylic acid, an organic monoamine, and an organic diamine, wherein the organic monocarboxylic acid is H(CH2).n COOH (n=1~10), benzoic acid or naphtholic acid; the organic dicarboxylic acid is HOOC(CH2). m COOH (m=1~10), terephthalic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid; the organic monoamine is H(CH2). x NH2, aniline, or naphthylamine; the organic diamine is H2N(CH2). y NH2 (y=1~10), p-phenylenediamine, o-phenylenediamine, m-phenylenediamine or naphthalenediamine, the amount of which added is 3~20% of the total amount of pyridine heterocyclic amide salt and aromatic structural amide salt.

[0010] In some embodiments, the mass ratio of the first cooling agent to the second cooling agent is 1:(0.5~1.5).

[0011] In some embodiments, the first cooling agent is selected from one or a combination of mica or jade powder.

[0012] In some embodiments, the second cooling agent is selected from one or a combination of boron nitride and aluminum nitride.

[0013] In some embodiments, the combined flame retardant, polyamide resin, and cooling compound additive are premixed and then melt-blended to obtain cooling flame retardant functional polyamide chips. A suitable temperature is selected within this range according to different matrix resins, and the temperature range is set to 200~305℃, and the screw speed is 30~100 rpm.

[0014] In some embodiments, 3 to 10 parts of a combined flame retardant, 100 parts of polyamide resin, and 0.5 to 1.5 parts of a cooling compound additive are premixed and then melt-blended to obtain cooling flame retardant polyamide chips.

[0015] In some embodiments, the polyamide resin is dried at 90~110°C for a period of time, and the cooling compound additive is dried at 60~100°C for a period of time. The combined flame retardant, polyamide resin, and cooling compound additive are premixed and then melt-blended to obtain cooling flame retardant polyamide chips.

[0016] In some embodiments, polyamide resin refers to one or a combination of PA6, PA66, PA56, PA610, PA1010, PA11, PA12, PA1012, PA1212, and PA1210.

[0017] In some embodiments, 10-15 parts of a pyridine heterocyclic amide salt, 10-15 parts of an aromatic structural amide salt, and 10-15 parts of deionized water are added to a high-pressure polymerization reactor.

[0018] In some embodiments, the air in the high-pressure polymerization reactor is replaced with nitrogen 3-5 times and the reactor is then sealed to create an inert gas atmosphere. This method uses nitrogen to replace the air to prevent the oxidation reaction of pyridine heterocyclic amide salts and aromatic amide salts with oxygen at high temperatures, thus avoiding side reactions and safety risks.

[0019] In some embodiments, when the reaction system is heated to 210~230°C, the pressure inside the high-pressure polymerization reactor is maintained at 1.5~2.5 MPa, and pre-polymerization is carried out at this temperature and pressure for 1~2 hours; the reaction system is further heated to 250~280°C, while the pressure inside the high-pressure polymerization reactor is reduced to atmospheric pressure within 0.5~1.0 hours; when the pressure is further reduced to -0.01~-0.05 MPa, the reaction system is adjusted to 260~290°C, and the reaction is carried out at this temperature and pressure for 10~30 minutes, wherein the reaction system is continuously stirred during the reaction process.

[0020] It should be noted that the reaction system is pre-polymerized at 210~230℃ and 1.5~2.5 MPa for 1~2 hours to allow the pyridine-containing heterocyclic amide salt and aromatic amide salt to uniformly initiate the reaction and form short-chain oligomers. The reaction continues at 250~280℃ and under depressurization to further extend the molecular chains and smoothly remove small molecule impurities such as water generated in the reaction, avoiding product loss. Finally, the reaction system is reacted at 260~290℃ and -0.01~-0.05 MPa for 10~30 minutes.

[0021] In some embodiments, the number average molecular weight of the combined flame retardant is 1000~7800 g / mol, and the molecular chain length of the combined flame retardant accommodates a sufficient amount of pyridine rings and aromatic rings, thereby achieving a dual synergistic effect of chemical and physical flame retardancy. Furthermore, the molecular weight difference between the combined flame retardant and the polyamide resin is moderate, so that the combined flame retardant has good compatibility with the polyamide.

[0022] Regarding the preparation of pyridine heterocyclic amide salts: A pyridine-containing dicarboxylic acid and an aliphatic diamine are added to water or ethanol and stirred at 60-90°C for 1-12 hours to carry out a salt formation reaction, yielding a pyridine-containing heterocyclic amide salt.

[0023] In some embodiments, the molar ratio of pyridine dicarboxylic acid to aliphatic diamine is 1:(1.02~1.05).

[0024] In some embodiments, the pyridine-containing dicarboxylic acid includes one or a combination of 2,6-pyridinedicarboxylic acid, 2,5-pyridinedicarboxylic acid, 2,4-pyridinedicarboxylic acid, 2,3-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, and 3,4-pyridinedicarboxylic acid.

[0025] In some embodiments, the aliphatic diamine is a straight-chain aliphatic diamine with 4 to 10 carbon atoms.

[0026] Preparation of aromatic amide salts: Aromatic dicarboxylic acids and aliphatic diamines are added to water or ethanol and stirred at 60-90°C for 1-12 hours to carry out a salt formation reaction, yielding amide salts containing aromatic structures.

[0027] In some embodiments, the molar ratio of aromatic dicarboxylic acid to aliphatic diamine is 1:(1.02~1.05).

[0028] In some embodiments, the aromatic dicarboxylic acid includes one or a combination of 1,3-phthalic acid, 1,4-phthalic acid, 2,3-naphthalic acid, 1,3-naphthalic acid, 1,4-naphthalic acid, 2,6-naphthalic acid, and 2,7-naphthalic acid.

[0029] In some embodiments, the aliphatic diamine is a straight-chain aliphatic diamine with 4 to 10 carbon atoms.

[0030] In some embodiments, the polyamide fiber with both cooling and flame-retardant properties obtained by this method has a breaking strength of 3.6~8.1 cN / dtex and a breaking elongation of 23.9~33.1%. The fabric prepared using the polyamide fiber with both cooling and flame-retardant properties of this invention has a contact cooling coefficient Q. max The limiting oxygen index of the fabric is 32.0-36.5%, ranging from 0.19 to 0.28 J / (cm²·s).

[0031] In some embodiments, cool-feeling flame-retardant polyamide chips are dried at 90~110°C for a period of time and then added to a melt spinning machine for spinning to obtain polyamide fibers with both cool-feeling and flame-retardant properties.

[0032] Furthermore, the melt spinning temperature is 280~295℃, and the winding speed is 3000~4500m / min.

[0033] Compared with existing technologies, this technical solution has the following characteristics and beneficial effects: 1. The polyamide fiber prepared by this invention, which combines cooling and flame-retardant properties, increases the effective contact between particles of cooling additives by introducing cooling additives with different particle sizes, thereby making the thermal conductive network denser and the thermal conductive path richer, thus improving the cooling performance of the polyamide fiber. Furthermore, based on the size complementarity between cooling additives, the cooling performance of the fiber can be effectively improved under micro-addition conditions, and the adverse effects on the fiber spinnability and mechanical properties can be effectively reduced.

[0034] (2) The combined flame retardant prepared in this invention achieves a dual synergistic flame retardant mechanism of "gas-phase free radical capture" and "physical droplet heat transfer" through molecular design. This design enables the material to efficiently prevent flame propagation through chemical means and rapidly remove heat through physical means during combustion.

[0035] (3) The polyamide fiber prepared by the present invention, which has both cooling and flame-retardant properties, has expanded its application scope from traditional industrial protection and basic clothing to summer close-fitting clothing, high-end home textiles, medical and health care, etc., significantly broadening its application boundaries in multiple fields. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0038] Example 1: A method for preparing polyamide 6 fiber with both cooling and flame-retardant properties, the specific steps of which are as follows: (1) Add 2,6-pyridinedicarboxylic acid and 1,6-hexanediamine to water in a molar ratio of 1:1.02 and stir at 60°C for 2 h to carry out a salt formation reaction to obtain amide salt A containing pyridine structure; add 1,3-phthalic acid and 1,6-hexanediamine to water in a molar ratio of 1:1.02 and stir at 60°C for 2 h to carry out a salt formation reaction to obtain amide salt B containing aromatic structure.

[0039] (2) By mass, add 10 parts of amide salt A, 12 parts of amide salt B, 0.7 parts of benzoic acid and 10 parts of deionized water to a high-pressure polymerization reactor. Replace the air in the reactor with nitrogen three times and then seal the reactor. Turn on the stirring and heat up. When the system temperature reaches 210℃, maintain the pressure in the reactor at 1.5MPa and pre-polymerize for 1 hour. Continue to heat up to 250℃ while slowly depressurizing. Reduce the pressure to atmospheric pressure within 0.5 hours. Continue to react for 10 minutes at a pressure of -0.01MPa and a temperature of 260℃. After the reaction is completed, stop stirring, purge with nitrogen and discharge the material. After water cooling, pelletizing and drying, a flame retardant containing pyridine and aromatic ring components with a molecular weight of 3300~3500g / mol is obtained.

[0040] (3) The polyamide 6 chips were dried at 90°C for 24 hours, and the cooling additive was dried at 60°C for 24 hours. A compound powder consisting of 6 parts flame retardant, 100 parts polyamide 6 chips, and 0.5 parts cooling additive (mass ratio 1:0.5, mica with a particle size of 300~340nm; boron nitride with a particle size of 30~50nm) was premixed and then melt-blended in a twin-screw extruder to obtain polyamide 6 chips with both cooling and flame-retardant properties. The melt blending was performed in a twin-screw extruder at a temperature range of 230~250°C and a screw speed of 60 rpm.

[0041] (4) The polyamide 6 chips with both cooling and flame retardant properties were dried at 95°C for 24 hours and then added to a melt spinning machine for spinning. The spinning temperature was 265°C and the winding speed was 4200 m / min to obtain polyamide 6 fibers with both cooling and flame retardant properties.

[0042] Example 2: A method for preparing polyamide 66 fiber with both cooling and flame-retardant properties, the specific steps of which are as follows: (1) Add 2,5-pyridinedicarboxylic acid and 1,10-decanediamine to water in a molar ratio of 1:1.05 and stir at 60°C for 3 h to carry out a salt formation reaction to obtain amide salt A containing pyridine structure; add 1,4-phthalic acid and 1,10-decanediamine to water in a molar ratio of 1:1.05 and stir at 60°C for 3 h to carry out a salt formation reaction to obtain amide salt B containing aromatic structure.

[0043] (2) By mass, add 15 parts of amide salt A, 10 parts of amide salt B, 0.8 parts of benzoic acid and 15 parts of deionized water to a high-pressure polymerization reactor. Replace the air in the reactor with nitrogen three times and then seal the reactor. Turn on the stirring and heat up. When the system temperature reaches 230℃, maintain the pressure in the reactor at 2.5MPa and pre-polymerize for 2 hours. Continue to heat up to 280℃ while slowly depressurizing. Reduce the pressure to atmospheric pressure within 1.0 hour. Continue to react for 30 minutes at a pressure of -0.05MPa and a temperature of 290℃. After the reaction is completed, stop stirring, purge with nitrogen and discharge the material. After water cooling, pelletizing and drying, a flame retardant containing pyridine and aromatic ring components with a molecular weight of 3400~3600g / mol is obtained.

[0044] (3) The polyamide 66 chips were dried at 100℃ for 24 hours, and the cooling additive was dried at 70℃ for 24 hours. A compound powder (mass ratio 1:1, mica with a particle size of 400-450 nm; aluminum nitride with a particle size of 60-80 nm) containing 7 parts flame retardant, 100 parts polyamide 66 chips, and 1 part cooling additive was premixed and then melt-blended in a twin-screw extruder to obtain polyamide 66 chips with both cooling and flame-retardant properties. The melt blending was performed in a twin-screw extruder at a temperature range of 265-280℃ and a screw speed of 30 rpm.

[0045] (4) The polyamide 66 chips with both cooling and flame retardant properties were dried at 100°C for 24 hours and then added to a melt spinning machine for spinning. The spinning temperature was 285°C and the winding speed was 3500 m / min to obtain polyamide 66 fibers with both cooling and flame retardant properties.

[0046] Example 3: A method for preparing polyamide 56 fiber with both cooling and flame-retardant properties, the specific steps of which are as follows: (1) Add 2,6-pyridinedicarboxylic acid and 1,8-octanediamine to water in a molar ratio of 1:1.05 and stir at 80°C for 12 h to carry out a salt formation reaction to obtain amide salt A containing pyridine structure; add 2,3-naphthalenedicarboxylic acid and 1,8-octanediamine to water in a molar ratio of 1:1.05 and stir at 80°C for 12 h to carry out a salt formation reaction to obtain amide salt B containing aromatic structure.

[0047] (2) By mass, add 15 parts of amide salt A, 13 parts of amide salt B, 0.9 parts of benzoic acid and 10 parts of deionized water to a high-pressure polymerization reactor. Replace the air in the reactor with nitrogen three times and then seal the reactor. Turn on the stirring and heat up. When the system temperature reaches 220℃, maintain the pressure in the reactor at 2MPa and pre-polymerize for 1.5 hours. Continue to heat up to 260℃ while slowly depressurizing. Reduce the pressure to atmospheric pressure within 1.0 hour. Continue to react for 20 minutes at a pressure of -0.03MPa and a temperature of 270℃. After the reaction is completed, stop stirring, purge with nitrogen and discharge the material. After water cooling, pelletizing and drying, a flame retardant containing pyridine and aromatic ring components with a molecular weight of 3400~3600g / mol is obtained.

[0048] (3) The polyamide 56 chips were dried at 105℃ for 36 hours, and the cooling additive was dried at 80℃ for 36 hours. A compound powder (mass ratio 1:1.5, jade powder with a particle size of 550~600nm; boron nitride with a particle size of 70~90nm) containing 6 parts flame retardant, 100 parts polyamide 56 chips, and 1.5 parts cooling additive was premixed and then melt-blended in a twin-screw extruder to obtain polyamide 56 chips with both cooling and flame-retardant properties. The twin-screw extruder temperature setting range was 255~285℃, and the screw speed was 90rpm.

[0049] (4) The polyamide 56 chips with both cooling and flame retardant properties were dried at 105°C for 36 hours and then added to a melt spinning machine for spinning. The spinning temperature was 295°C and the winding speed was 3000 m / min to obtain polyamide 56 fibers with both cooling and flame retardant properties.

[0050] Example 4: A method for preparing polyamide 610 fiber with both cooling and flame-retardant properties, the specific steps of which are as follows: (1) Add 2,5-pyridinedicarboxylic acid and 1,8-octanediamine to water in a molar ratio of 1:1.02 and stir at 70°C for 12 h to carry out a salt formation reaction to obtain amide salt A containing pyridine structure; add 2,6-naphthalenedicarboxylic acid and 1,8-octanediamine to water in a molar ratio of 1:1.02 and stir at 70°C for 12 h to carry out a salt formation reaction to obtain amide salt B containing aromatic structure.

[0051] (2) By mass, 12 parts of amide salt A, 15 parts of amide salt B, 1.0 parts of benzoic acid and 10 parts of deionized water were added to a high-pressure polymerization reactor. The reactor was sealed after the air inside was replaced with nitrogen three times. Stirring was started and the temperature was increased. When the system temperature reached 220℃, the pressure inside the reactor was maintained at 2.5MPa for 2 hours of pre-polymerization. The temperature was increased to 275℃ while the pressure was slowly released. The pressure was reduced to atmospheric pressure within 0.75 hours. The reaction was continued for 30 minutes at a pressure of -0.03MPa and a temperature of 290℃. After the reaction was completed, stirring was stopped, nitrogen was introduced and the product was discharged. After water cooling, pelletizing and drying, a flame retardant containing pyridine and aromatic ring components with a molecular weight of 2900~3200g / mol was obtained.

[0052] (3) The polyamide 610 chips were dried at 105℃ for 24 hours, and the cooling additive was dried at 80℃ for 24 hours. A compound powder (mass ratio 1:0.5, jade powder with a particle size of 420~450nm; aluminum nitride with a particle size of 80~90nm) was premixed and then melt-blended in a twin-screw extruder to obtain polyamide 610 chips with both cooling and flame-retardant properties. The twin-screw extruder temperature setting range was 230~265℃, and the screw speed was 75rpm.

[0053] (4) The polyamide 610 chips with both cooling and flame retardant properties were dried at 105°C for 24 hours and then added to a melt spinning machine for spinning. The spinning temperature was 282°C and the winding speed was 3800 m / min to obtain polyamide 610 fibers with both cooling and flame retardant properties.

[0054] Example 5: A method for preparing polyamide 1010 fiber with both cooling and flame-retardant properties, the specific steps of which are as follows: (1) Add 2,6-pyridinedicarboxylic acid and 1,7-heptanediamine to water in a molar ratio of 1:1.02 and stir at 60°C for 2 h to carry out a salt formation reaction to obtain amide salt A containing pyridine structure; add 1,4-phthalic acid and 1,7-heptanediamine to water in a molar ratio of 1:1.02 and stir at 80°C for 2 h to carry out a salt formation reaction to obtain amide salt B containing aromatic structure.

[0055] (2) By mass, 13 parts of amide salt A, 15 parts of amide salt B, 1.1 parts of benzoic acid and 12 parts of deionized water were added to a high-pressure polymerization reactor. The reactor was sealed after the air inside was replaced with nitrogen three times. Stirring was started and the temperature was increased. When the system temperature reached 210℃, the pressure inside the reactor was maintained at 2.0MPa for 1 hour of pre-polymerization. The temperature was increased to 250℃ and the pressure was slowly released. The pressure was reduced to atmospheric pressure within 1 hour. The reaction was continued for 20 minutes at a pressure of -0.05MPa and a temperature of 290℃. After the reaction was completed, stirring was stopped, nitrogen was introduced and the product was discharged. After water cooling, pelletizing and drying, a flame retardant containing pyridine and aromatic ring components with a molecular weight of 2700~3000g / mol was obtained.

[0056] (3) The polyamide 1010 chips were dried at 100℃ for 36 hours, and the cooling additive was dried at 70℃ for 36 hours. A compound powder (mass ratio 1:1, jade powder with a particle size of 550~600nm; boron nitride with a particle size of 30~50nm) containing 8 parts flame retardant, 100 parts polyamide 1010 chips, and 1.5 parts cooling additive was premixed and then melt-blended in a twin-screw extruder to obtain polyamide 1010 chips with both cooling and flame-retardant properties. The twin-screw extruder temperature setting range was 220~255℃, and the screw speed was 100rpm.

[0057] (4) The polyamide 1010 chips with both cooling and flame retardant properties were dried at 105°C for 24 hours and then added to a melt spinning machine for spinning. The spinning temperature was 250°C and the winding speed was 4500 m / min to obtain polyamide 1010 fibers with both cooling and flame retardant properties.

[0058] Example 6: A method for preparing polyamide 11 fiber with both cooling and flame-retardant properties, the specific steps of which are as follows: (1) Add 2,4-pyridinedicarboxylic acid and 1,10-decanediamine to water in a molar ratio of 1:1.05 and stir at 60°C for 2 h to carry out a salt formation reaction to obtain amide salt A containing pyridine structure; add 2,3-naphthalenedicarboxylic acid and 1,6-hexanediamine to water in a molar ratio of 1:1.05 and stir at 80°C for 2 h to carry out a salt formation reaction to obtain amide salt B containing aromatic structure.

[0059] (2) By mass, add 15 parts of amide salt A, 10 parts of amide salt B, 0.75 parts of benzoic acid and 10 parts of deionized water to a high-pressure polymerization reactor. Replace the air in the reactor with nitrogen three times and then seal the reactor. Turn on the stirring and heat up. When the system temperature reaches 230℃, maintain the pressure in the reactor at 1.5MPa and pre-polymerize for 1 hour. Continue to heat up to 280℃ while slowly depressurizing. Reduce the pressure to atmospheric pressure within 0.75 hours. Continue to react for 10 minutes at a pressure of -0.01MPa and a temperature of 290℃. After the reaction is completed, stop stirring, purge with nitrogen and discharge the material. After water cooling, pelletizing and drying, a flame retardant containing pyridine and aromatic ring components with a molecular weight of 3500~3900g / mol is obtained.

[0060] (3) The polyamide 11 chips were dried at 90°C for 36 hours, and the cooling additive was dried at 90°C for 36 hours. A compound powder consisting of 10 parts flame retardant, 100 parts polyamide 11 chips, and 0.5 parts cooling additive (mass ratio 1:1.5, mica with a particle size of 300-350 nm; aluminum nitride with a particle size of 50-60 nm) was premixed and then melt-blended in a twin-screw extruder to obtain polyamide 11 chips with both cooling and flame-retardant properties. The twin-screw extruder temperature setting range was 210-235°C, and the screw speed was 45 rpm.

[0061] (4) The polyamide 11 chips with both cooling and flame retardant properties were dried at 110°C for 24 hours and then added to a melt spinning machine for spinning. The spinning temperature was 235°C and the winding speed was 3200 m / min to obtain polyamide 11 fibers with both cooling and flame retardant properties.

[0062] Example 7: A method for preparing polyamide 12 fiber with both cooling and flame-retardant properties, the specific steps of which are as follows: (1) Add 2,6-pyridinedicarboxylic acid and 1,10-decanediamine to water in a molar ratio of 1:1.05 and stir at 60°C for 2 h to carry out a salt formation reaction to obtain amide salt A containing pyridine structure; add 2,3-naphthalenedicarboxylic acid and 1,6-hexanediamine to water in a molar ratio of 1:1.05 and stir at 80°C for 2 h to carry out a salt formation reaction to obtain amide salt B containing aromatic structure.

[0063] (2) By mass, add 10 parts of amide salt A, 12 parts of amide salt B, 0.9 parts of benzoic acid and 10 parts of deionized water to a high-pressure polymerization reactor. Replace the air in the reactor with nitrogen three times and then seal the reactor. Turn on the stirring and heat up. When the system temperature reaches 230℃, maintain the pressure in the reactor at 1.5MPa and pre-polymerize for 1 hour. Continue to heat up to 280℃ while slowly depressurizing. Reduce the pressure to atmospheric pressure within 0.75 hours. Continue to react for 10 minutes at a pressure of -0.01MPa and a temperature of 290℃. After the reaction is completed, stop stirring, purge with nitrogen and discharge the material. After water cooling, pelletizing and drying, a flame retardant containing pyridine and aromatic ring components with a molecular weight of 3600~3900g / mol is obtained.

[0064] (3) The polyamide 12 chips were dried at 80℃ for 36 hours, and the cooling additive was dried at 90℃ for 36 hours. A compound powder consisting of 6 parts flame retardant, 100 parts polyamide 12 chips, and 0.8 parts cooling additive (mass ratio 1:1.5, mica with a particle size of 300~350nm; aluminum nitride with a particle size of 30~60nm) was premixed and then melt-blended in a twin-screw extruder to obtain polyamide 12 chips with both cooling and flame-retardant properties. The twin-screw extruder temperature setting range was 200~230℃, and the screw speed was 45rpm.

[0065] (4) The polyamide 12 chips with both cooling and flame retardant properties were dried at 80°C for 24 hours and then added to a melt spinning machine for spinning. The spinning temperature was 230°C and the winding speed was 3000 m / min to obtain polyamide 12 fibers with both cooling and flame retardant properties.

[0066] Example 8: A method for preparing polyamide 1012 fiber with both cooling and flame-retardant properties, the specific steps of which are as follows: (1) Add 2,5-pyridinedicarboxylic acid and 1,10-decanediamine to water in a molar ratio of 1:1.03 and stir at 70°C for 2 h to carry out a salt formation reaction to obtain amide salt A containing pyridine structure; add 2,3-naphthalenedicarboxylic acid and 1,6-hexanediamine to water in a molar ratio of 1:1.03 and stir at 80°C for 2 h to carry out a salt formation reaction to obtain amide salt B containing aromatic structure.

[0067] (2) By mass, 12 parts of amide salt A, 13 parts of amide salt B, 1.0 parts of benzoic acid and 10 parts of deionized water are added to a high-pressure polymerization reactor. The reactor is sealed after the air inside is replaced with nitrogen three times. Stirring is started and the temperature is increased. When the system temperature reaches 230℃, the pressure inside the reactor is maintained at 1.5MPa for 1 hour of pre-polymerization. The temperature is increased to 280℃ while the pressure is slowly released. The pressure is reduced to atmospheric pressure within 0.75 hours. The reaction is continued for 10 minutes at a pressure of -0.01MPa and a temperature of 290℃. After the reaction is completed, stirring is stopped, nitrogen is introduced and the material is discharged. After water cooling, pelletizing and drying, a flame retardant containing pyridine structure and aromatic ring structure components with a molecular weight of 3100~3400g / mol is obtained.

[0068] (3) The polyamide 1012 chips were dried at 110℃ for 36 hours, and the cooling additive was dried at 90℃ for 36 hours. A compound powder (mass ratio 1:1.5, mica with a particle size of 300~350nm; aluminum nitride with a particle size of 30~60nm) consisting of 5 parts flame retardant, 100 parts polyamide 1012 chips, and 1.2 parts cooling additive was premixed and then melt-blended in a twin-screw extruder to obtain polyamide 1012 chips with both cooling and flame-retardant properties. The twin-screw extruder temperature setting range was 210~245℃, and the screw speed was 45rpm.

[0069] (4) The polyamide 1012 chips with both cooling and flame retardant properties were dried at 80°C for 24 hours and then added to a melt spinning machine for spinning. The spinning temperature was 240°C and the winding speed was 3400 m / min to obtain polyamide 1012 fibers with both cooling and flame retardant properties.

[0070] Example 9: A method for preparing polyamide 1212 fiber with both cooling and flame-retardant properties, the specific steps of which are as follows: (1) Add 2,4-pyridinedicarboxylic acid and 1,10-decanediamine to water in a molar ratio of 1:1.03 and stir at 70°C for 2 h to carry out a salt formation reaction to obtain amide salt A containing pyridine structure; add 2,3-naphthalenedicarboxylic acid and 1,6-hexanediamine to water in a molar ratio of 1:1.03 and stir at 80°C for 2 h to carry out a salt formation reaction to obtain amide salt B containing aromatic structure.

[0071] (2) By mass, add 8 parts of amide salt A, 12 parts of amide salt B, 0.8 parts of benzoic acid and 10 parts of deionized water to a high-pressure polymerization reactor. Replace the air in the reactor with nitrogen three times and then seal the reactor. Turn on the stirring and heat up. When the system temperature reaches 230℃, maintain the pressure in the reactor at 1.5MPa and pre-polymerize for 1 hour. Continue to heat up to 280℃ while slowly depressurizing. Reduce the pressure to atmospheric pressure within 0.75 hours. Continue to react for 10 minutes at a pressure of -0.01MPa and a temperature of 290℃. After the reaction is completed, stop stirring, purge with nitrogen and discharge the material. After water cooling, pelletizing and drying, a flame retardant containing pyridine and aromatic ring components with a molecular weight of 2900~3100g / mol is obtained.

[0072] (3) The polyamide 1212 chips were dried at 110℃ for 36 hours, and the cooling additive was dried at 90℃ for 36 hours. A compound powder (mass ratio 1:1.5, mica with a particle size of 300~350nm; aluminum nitride with a particle size of 30~60nm) consisting of 5 parts flame retardant, 100 parts polyamide 1212 chips, and 1.2 parts cooling additive was premixed and then melt-blended in a twin-screw extruder to obtain polyamide 1212 chips with both cooling and flame-retardant properties. The twin-screw extruder temperature setting range was 200~230℃, and the screw speed was 45rpm.

[0073] (4) The polyamide 1212 chips with both cooling and flame retardant properties were dried at 80°C for 24 hours and then added to a melt spinning machine for spinning. The spinning temperature was 230°C and the winding speed was 3100 m / min to obtain polyamide 1212 fibers with both cooling and flame retardant properties.

[0074] Example 10: A method for preparing polyamide 1210 fiber with both cooling and flame-retardant properties, the specific steps of which are as follows: (1) Add 2,3-pyridinedicarboxylic acid and 1,10-decanediamine to water in a molar ratio of 1:1.03 and stir at 70°C for 2 h to carry out a salt formation reaction to obtain amide salt A containing pyridine structure; add 2,3-naphthalenedicarboxylic acid and 1,6-hexanediamine to water in a molar ratio of 1:1.03 and stir at 80°C for 2 h to carry out a salt formation reaction to obtain amide salt B containing aromatic structure.

[0075] (2) By mass, add 10 parts of amide salt A, 15 parts of amide salt B, 1.2 parts of benzoic acid and 10 parts of deionized water to a high-pressure polymerization reactor. Replace the air in the reactor with nitrogen three times and then seal the reactor. Turn on the stirring and heat up. When the system temperature reaches 230℃, maintain the pressure in the reactor at 1.5MPa and pre-polymerize for 1 hour. Continue to heat up to 280℃ while slowly depressurizing. Reduce the pressure to atmospheric pressure within 0.75 hours. Continue to react for 10 minutes at a pressure of -0.01MPa and a temperature of 290℃. After the reaction is completed, stop stirring, purge with nitrogen and discharge the material. After water cooling, pelletizing and drying, a flame retardant containing pyridine and aromatic ring components with a molecular weight of 2900~3100g / mol is obtained.

[0076] (3) The polyamide 1210 chips were dried at 110℃ for 36 hours, and the cooling additive was dried at 90℃ for 36 hours. A compound powder (mass ratio 1:1.5, mica with a particle size of 300~350nm; aluminum nitride with a particle size of 30~60nm) containing 7 parts flame retardant, 100 parts polyamide 1210 chips, and 1.0 part cooling additive was premixed and then melt-blended in a twin-screw extruder to obtain polyamide 1210 chips with both cooling and flame-retardant properties. The twin-screw extruder temperature setting range was 210~250℃, and the screw speed was 45rpm.

[0077] (4) The polyamide 1210 chips with both cooling and flame retardant properties were dried at 80°C for 24 hours and then added to a melt spinning machine for spinning. The spinning temperature was 230°C and the winding speed was 3100 m / min to obtain polyamide 1210 fibers with both cooling and flame retardant properties.

[0078] Comparative Example 1 Polyamide 6 chips were dried at 95℃ for 24 hours and then added to a melt spinning machine for spinning at a spinning temperature of 265℃ and a winding speed of 4200 m / min to obtain polyamide 6 fibers.

[0079] Comparative Example 2 Polyamide 66 chips were dried at 110℃ for 24 hours and then added to a melt spinning machine for spinning at a spinning temperature of 285℃ and a winding speed of 4000m / min to obtain polyamide 66 fibers.

[0080] Comparative Example 3 Polyamide 56 chips were dried at 105℃ for 36 hours and then added to a melt spinning machine for spinning at a spinning temperature of 295℃ and a winding speed of 3000m / min to obtain polyamide 56 fibers. Comparative Example 4 Polyamide 610 chips were dried at 105℃ for 24 hours and then added to a melt spinning machine for spinning at a spinning temperature of 282℃ and a winding speed of 3800m / min to obtain polyamide 610 fibers.

[0081] Comparative Example 5 Polyamide 1010 chips were dried at 100℃ for 36 hours and then added to a melt spinning machine for spinning at a spinning temperature of 250℃ and a winding speed of 4500m / min to obtain polyamide 1010 fibers. Comparative Example 6 Polyamide 11 chips were dried at 90℃ for 24 hours and then added to a melt spinning machine for spinning at a spinning temperature of 235℃ and a winding speed of 3200 m / min to obtain polyamide 11 fibers. Comparative Example 7 Polyamide 12 chips were dried at 90℃ for 24 hours and then added to a melt spinning machine for spinning at a spinning temperature of 230℃ and a winding speed of 3000m / min to obtain polyamide 12 fibers. Comparative Example 8 Polyamide 1012 chips were dried at 90℃ for 24 hours and then added to a melt spinning machine for spinning at a spinning temperature of 240℃ and a winding speed of 3400 m / min to obtain polyamide 1012 fibers.

[0082] Comparative Example 9 Polyamide 1212 chips were dried at 90℃ for 24 hours and then added to a melt spinning machine for spinning at a spinning temperature of 230℃ and a winding speed of 3100m / min to obtain polyamide 1212 fibers.

[0083] Comparative Example 10 Polyamide 1210 chips were dried at 90℃ for 24 hours and then added to a melt spinning machine for spinning at a spinning temperature of 230℃ and a winding speed of 3100m / min to obtain polyamide 1210 fibers.

[0084] Table 1 Performance Test Tables for Various Embodiments and Comparative Examples

[0085] Those skilled in the art should understand that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0086] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for preparing polyamide fibers with both cooling and flame-retardant properties, characterized in that, Includes the following steps: A reaction system consisting of pyridine heterocyclic amide salt, aromatic amide salt, molecular weight regulator and deionized water is added to a high-pressure polymerization reactor. The reaction system is subjected to a staged reaction under an inert gas atmosphere with controlled temperature and pressure to obtain a combined flame retardant. The combination flame retardant, polyamide resin, and cooling compound additive are premixed and then melt-blended to obtain cooling flame retardant functional polyamide chips, wherein the cooling compound additive includes at least two cooling additives with different particle sizes. Polyamide fibers with both cooling and flame-retardant properties are obtained by melt spinning of polyamide chips with cooling and flame-retardant properties.

2. The method for preparing polyamide fibers with both cooling and flame-retardant properties according to claim 1, characterized in that, The cooling compound additive includes a first cooling aid and a second cooling aid with different particle sizes, wherein the particle size of the first cooling aid is 300~600nm and the particle size of the second cooling aid is 30~90nm.

3. The method for preparing polyamide fibers with both cooling and flame-retardant properties according to claim 1, characterized in that, The molecular weight regulator is one or a combination of organic monocarboxylic acid, organic dicarboxylic acid, organic monoamine, and organic diamine, wherein the organic monocarboxylic acid is H(CH2). n COOH (n=1~10), benzoic acid or naphtholic acid; the organic dicarboxylic acid is HOOC(CH2). m COOH (m=1~10), terephthalic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid; the organic monoamine is H(CH2). x NH2, aniline, or naphthylamine; the organic diamine is H2N(CH2). y NH2 (y=1~10), p-phenylenediamine, o-phenylenediamine, m-phenylenediamine or naphthalenediamine, the amount of which added is 3~20% of the total amount of pyridine heterocyclic amide salt and aromatic structural amide salt.

4. The method for preparing polyamide fibers with both cooling and flame-retardant properties according to claim 2, characterized in that, The mass ratio of the first cooling agent to the second cooling agent is 1:(0.5~1.5).

5. The method for preparing polyamide fibers with both cooling and flame-retardant properties according to claim 2, characterized in that, The first cooling agent is selected from one or a combination of mica or jade powder; the second cooling agent is selected from one or a combination of boron nitride and aluminum nitride.

6. The method for preparing polyamide fibers with both cooling and flame-retardant properties according to claim 1, characterized in that, The combination flame retardant, polyamide resin, and cooling compound additive are premixed and then melt-blended to obtain cooling flame retardant polyamide chips. The appropriate temperature is selected within this range according to different matrix resins, and the temperature range is set to 200~305℃, and the screw speed is 30~100rpm.

7. The method for preparing polyamide fibers with both cooling and flame-retardant properties according to claim 1, characterized in that, The cool-feeling flame-retardant polyamide chips are obtained by premixing 3-10 parts of the combined flame retardant, 100 parts of the polyamide resin, and 0.5-1.5 parts of the cooling compound additive.

8. The method for preparing polyamide fibers with both cooling and flame-retardant properties according to claim 1, characterized in that, Polyamide resin refers to one or a combination of PA6, PA66, PA56, PA610, PA1010, PA11, PA12, PA1012, PA1212, and PA1210.

9. The method for preparing polyamide fibers with both cooling and flame-retardant properties according to claim 1, characterized in that, After drying the polyamide resin at 90~110℃ for a period of time and drying the cooling compound additive at 60~100℃ for a period of time, the combined flame retardant, polyamide resin, and cooling compound additive are premixed and then melt-blended to obtain cooling flame retardant polyamide chips.

10. The method for preparing polyamide fibers with both cooling and flame-retardant properties according to claim 1, characterized in that, Polyamide fibers, which combine cooling and flame-retardant properties, have a tensile strength of 3.6~8.1 cN / dtex, a breaking elongation of 23.9~33.1%, and a contact cooling coefficient Q. max The limiting oxygen index of the fabric is 32.0-36.5%, ranging from 0.19 to 0.28 J / (cm²·s).

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