High-strength polyamide fiber composite material and preparation method thereof

Abstract

The invention relates to the technical field of modified fibers, and discloses a high-strength polyamide fiber composite material and a preparation method thereof.4-vinylpyridine, 16-bromohexadecanoic acid, 2, 4, 6, 8-tetramethylcyclotetrasiloxane and the like are used as raw materials, a cyclic organosilicon quaternary ammonium salt carboxylic acid monomer is obtained through quaternization and hydrosilylation reaction and polymerized with ethidene diamine, and the high-strength polyamide fiber composite material is obtained. According to the similar compatibility principle, the organosilicon quaternary ammonium salt hyperbranched polyamide and PA6 slices are subjected to melt blending and spinning, and the high-strength polyamide fiber composite material is obtained. A quaternary ammonium salt structure and an amide structure have hydrophilicity, an alkyl long chain has hydrophobicity, and hydrophilic-hydrophobic combination is beneficial to penetration of quaternary ammonium salt molecules through bacterial cell membranes, so that a bactericidal effect is achieved; the cyclic organic silicon and the hyperbranched polyamide have large crosslinking density, stress can be better dispersed and transmitted when the cyclic organic silicon and the hyperbranched polyamide are subjected to external force, stress concentration is avoided, and therefore the effect of reinforcing and toughening the polyamide fiber is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of modified fibers, and in particular to a high-strength nylon fiber composite material and a preparation method thereof. Background Art

[0002] With the rapid development of modern science and technology, fiber materials are increasingly used in various fields. Polyamide fiber (nylon fiber) has high strength and high elastic recovery rate. It is the chemical fiber with the best wear resistance among existing fibers. Its wear resistance is 10 times higher than that of silk and cotton and 20 times higher than that of wool. Nylon fiber has good dyeing performance and moderate hygroscopicity. It has good applications in three major fields such as clothing, industry and decorative carpets. However, since nylon fiber is very easy to generate static electricity, the surface of the fabric is easily contaminated with dust, and with the discharge of human sweat, bacteria are very easy to multiply on the surface of the fabric, thus affecting human health. With the continuous progress of society and the diversification of consumer demand, higher requirements are placed on the mechanical properties and antibacterial properties of nylon fiber. Therefore, it is of great practical significance to develop a high-strength nylon fiber composite material to meet market demand.

[0003] The nylon fibers currently available on the market are mainly improved by adding various additives or chemically modifying them to improve their performance. For example, by adding chemical additives such as toughening agents and chain extenders, the toughness and strength of nylon fibers can be improved; by physical or chemical modification methods, such as copolymerization and cross-linking, the wear resistance and heat resistance of nylon fibers can be further improved. However, while these methods improve the performance of nylon fibers, they also bring some problems, such as complex preparation process, increased cost, environmental pollution, etc.; for example, patent number CN118895589A discloses a high-strength nylon filament and its preparation method, which arranges and combines nylon yarn and polypropylene fiber yarn in a special arrangement mode, and makes the outer layer, middle layer and inner layer of the silk thread bonded more tightly and more evenly stressed by spiral winding, which has a good promoting effect on enhancing the overall performance of nylon filament; however, the process is complicated and not suitable for industrial production, and does not significantly improve the antibacterial properties of nylon fibers.

[0004] Patent CN114672894B discloses an antibacterial nylon yarn and its preparation process. The antibacterial nylon yarn is made of antibacterial masterbatch and ordinary masterbatch, wherein the antibacterial masterbatch is mainly composed of nanosilver loaded on graphene oxide sheets, which improves the problem of easy oxidation and discoloration of nanosilver to a certain extent. At the same time, the graphene oxide / nanosilver composite material can reduce the release rate of nanosilver and play a slow-release antibacterial effect. However, due to the dark color of graphene oxide, it is difficult to change the color of the fiber by subsequent dyeing. In addition, due to the particularity of the nanostructure, graphene oxide and nanosilver have high surface energy and are easy to agglomerate. When they are prepared with nylon fiber materials only by melt blending, they are prone to uneven dispersion due to agglomeration, thereby reducing the antibacterial and mechanical properties of the antibacterial nylon fiber.

[0005] Hyperbranched polymers have the characteristics of having many branching points and the molecular chains being not easily entangled, etc., and have broad application prospects in high-molecular materials such as fibers; the patent with the publication number CN114106355B discloses the use of a reactive amphiphilic hyperbranched polymer as a formaldehyde-free acid fixing agent, which can improve the soaping color fastness and rubbing color fastness grades after acid dyes are dyed on polyamide fabrics, but this hyperbranched formaldehyde-free acid fixing agent does not improve the antibacterial and mechanical properties of polyamide fibers. The purpose of this application is to prepare a novel hyperbranched polyamide with a quaternary ammonium salt antibacterial group and a tough epoxy organosilicon structure, which has good compatibility with PA6, so as to improve the problems of poor mechanical and antibacterial properties of polyamide fibers. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies existing in the prior art, and provides a high-strength polyamide fiber composite material and its preparation method, which solves the problems of poor antibacterial and mechanical properties of polyamide fibers, and further improves the hydrophilicity and moisture permeability of polyamide fibers.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A preparation method of a high-strength polyamide fiber composite material is carried out according to the following steps:

[0009] Step (1): Under a nitrogen atmosphere, add a cyclic organosilicon quaternary ammonium salt carboxylic acid monomer, thionyl chloride and a catalyst N,N-dimethylformamide to a reaction flask, react at 70 - 80 °C for 2 - 4 h, concentrate under reduced pressure, and after drying, add an N,N-dimethylacetamide solvent, ethylenediamine and triethylamine. First, react in an ice-water bath for 1 - 3 h, and then react at 30 - 45 °C for 12 - 24 h, concentrate under reduced pressure, and after drying, obtain an organosilicon quaternary ammonium salt hyperbranched polyamide.

[0010] Step (2): Under a nitrogen atmosphere, add 100 parts by weight of PA6 chips, 2 - 10 parts of the organosilicon quaternary ammonium salt hyperbranched polyamide and 0.2 - 0.5 part of an antioxidant to a spinning machine, carry out melt blending at 220 - 235 °C, then carry out spinning at 240 - 255 °C, and then stretch and heat-set the fibers through a hot roll drawing machine to obtain a high-strength polyamide fiber composite material.

[0011] Furthermore, in step (1), the molar ratio relationship of the cyclic organosilicon quaternary ammonium salt carboxylic acid monomer, thionyl chloride, ethylenediamine and triethylamine is 1:5 - 8:4.2 - 6:7 - 10.

[0012] Furthermore, in step (2), the antioxidant is 2,6-di-tert-butyl-4-methylphenol.

[0013] Further, the drawing ratio in step (2) is 3 - 5 times, and the heat setting temperature is 100 - 110 °C.

[0014] Further, the preparation method of the cyclic organosilicon quaternary ammonium salt carboxylic acid monomer in step (1) is carried out according to the following steps:

[0015] Step S1: Under a nitrogen atmosphere, 4-vinylpyridine and acetonitrile solvent are added to a reaction flask. After stirring evenly, 16-bromohexadecanoic acid is added, and the mixture is stirred for reaction. After the reaction is completed, it is cooled to room temperature, concentrated under reduced pressure, and separated by column chromatography (ethyl acetate / petroleum ether = 1:10). The organic phase is concentrated and dried to obtain the alkenyl quaternary ammonium salt monomer.

[0016] Step S2: Under a nitrogen atmosphere, 2,4,6,8-tetramethylcyclotetrasiloxane, chloroplatinic acid, and toluene solvent are added to a reaction flask. After stirring evenly, the alkenyl quaternary ammonium salt intermediate is added, and the mixture is stirred for reaction. After the reaction is completed, it is cooled to room temperature and concentrated under reduced pressure to obtain the cyclic organosilicon quaternary ammonium salt carboxylic acid monomer.

[0017] Further, the proportional relationship between 4-vinylpyridine and 16-bromohexadecanoic acid in step S1 is 1:1.05 - 1.2.

[0018] Further, the reaction temperature in step S1 is 65 - 80 °C, and the reaction time is 8 - 16 h.

[0019] Further, the molar proportional relationship between 2,4,6,8-tetramethylcyclotetrasiloxane, chloroplatinic acid, and the alkenyl quaternary ammonium salt intermediate in step S2 is 1:0.002 - 0.004:1.1 - 1.3.

[0020] Further, the reaction temperature in step S2 is 95 - 110 °C, and the reaction time is 3 - 5 h.

[0021] Adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0022] The present invention uses 4-vinylpyridine, 16-bromohexadecanoic acid, 2,4,6,8-tetramethylcyclotetrasiloxane, etc. as reactants, and prepares the cyclic organosilicon quaternary ammonium salt carboxylic acid monomer through quaternization and hydrosilylation reactions. Multiple carboxyl groups in its structure can carry out polymerization reactions with ethylenediamine to obtain organosilicon quaternary ammonium salt hyperbranched polyamide. According to the principle of similar compatibility, it is melt-blended and spun with PA6 chips to obtain a high-strength polyamide fiber composite material.

[0023] The quaternary ammonium salt structure and amide structure in organosilicon quaternary ammonium salt hyperbranched polyamide are hydrophilic, while the alkyl long chain is hydrophobic. This hydrophilic-hydrophobic combination enables them to form a stable structure in aqueous solution, facilitating the penetration of quaternary ammonium salt molecules through the bacterial cell membrane, interacting with the cell membranes of bacteria such as Escherichia coli, changing the cell membrane permeability, and disrupting the bacterial metabolic process, thereby achieving a bactericidal effect.

[0024] The organosilicon quaternary ammonium salt hyperbranched polyamide contains a polyamide structure, which is similar and compatible with PA6, and the two can be melt-blended and spun well; the hyperbranched polyamide has a three-dimensional branched molecular chain, forming physical chain entanglements with the PA6 molecular chain to form a crosslinked network, which is beneficial to improving the breaking strength of nylon fibers; at the same time, the cyclic organosilicon structure in the organosilicon quaternary ammonium salt hyperbranched polyamide has a silicon-oxygen bond with a relatively high bond energy, which can absorb more energy when subjected to impact; in addition, due to the large network structure and cavity structure of the hyperbranched polymer, it has a relatively high crosslinking density, and the hyperbranched polymer can be used as a dispersion, uniformly dispersed in the PA6 matrix, and can better disperse and transfer stress when subjected to external forces, avoiding material damage caused by stress concentration, thereby enhancing and toughening the nylon fiber. Detailed implementation mode

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] Unless otherwise specified, the raw materials and reagents used in this application are all commercially available products or can be prepared by known methods.

[0027] 4-Vinylpyridine, CAS number is 100-43-6.

[0028] 16-Bromohexadecanoic acid, CAS number is 2536-35-8.

[0029] 2,4,6,8-Tetramethylcyclotetrasiloxane, CAS number is 2370-88-9.

[0030] Example 1

[0031] (1) Under a nitrogen atmosphere, 50 mmol of 4-vinylpyridine and 200 mL of acetonitrile solvent were added to a reaction flask. After stirring evenly, 56 mmol of 16-bromohexadecanoic acid was added, and the reaction was carried out at 70 °C for 12 h. After cooling to room temperature, it was concentrated under reduced pressure, and column chromatography separation (ethyl acetate / petroleum ether = 1:10) was carried out. The organic phase was concentrated and dried to obtain the alkenyl quaternary ammonium salt monomer. The preparation reaction formula is as follows:

[0032]

[0033] (2) Under a nitrogen atmosphere, 40 mmol of 2,4,6,8-tetramethylcyclotetrasiloxane, 0.12 mmol of chloroplatinic acid and 280 mL of toluene solvent were added to the reaction flask. After stirring evenly, 48 mmol of alkenyl quaternary ammonium salt intermediate was added, and the reaction was carried out at 105 °C for 4 h. After cooling to room temperature, it was concentrated under reduced pressure to obtain a cyclic organosilicon quaternary ammonium salt carboxylic acid monomer. The preparation reaction formula is as follows:

[0034]

[0035] (3) Under a nitrogen atmosphere, 35 mmol of cyclic organosilicon quaternary ammonium salt carboxylic acid monomer, 210 mmol of thionyl chloride and 2.1 mL of catalyst N,N-dimethylformamide were added to the reaction flask. The reaction was carried out at 75 °C for 3 h, concentrated under reduced pressure, and after drying, 420 mL of N,N-dimethylacetamide solvent, 175 mmol of ethylenediamine and 300 mmol of triethylamine were added. The reaction was first carried out in an ice-water bath for 2 h, and then at 40 °C for 16 h. After concentration under reduced pressure and drying, an organosilicon quaternary ammonium salt hyperbranched polyamide was obtained.

[0036] (4) Under a nitrogen atmosphere, 100 g of PA6 chips, 2 g of organosilicon quaternary ammonium salt hyperbranched polyamide and 0.4 g of antioxidant 2,6-di-tert-butyl-4-methylphenol were added to the spinning machine, melt-blended at 225 °C, then spun at 250 °C, and then the fibers were drawn and heat-set through a hot roll drawing machine, where the drawing ratio was 4 times and the heat-setting temperature was 105 °C to obtain a high-strength polyamide fiber composite material.

[0037] Example 2

[0038] (1) Under a nitrogen atmosphere, 150 mmol of 4-vinylpyridine and 450 mL of acetonitrile solvent were added to the reaction flask. After stirring evenly, 157.5 mmol of 16-bromohexadecanoic acid was added, and the reaction was carried out at 80 °C for 8 h. After cooling to room temperature, it was concentrated under reduced pressure, separated by column chromatography (ethyl acetate / petroleum ether = 1:10), and the organic phase was concentrated and dried to obtain an alkenyl quaternary ammonium salt monomer.

[0039] (2) Under a nitrogen atmosphere, 130 mmol of 2,4,6,8-tetramethylcyclotetrasiloxane, 0.26 mmol of chloroplatinic acid and 780 mL of toluene solvent were added to the reaction flask. After stirring evenly, 143 mmol of alkenyl quaternary ammonium salt intermediate was added, and the reaction was carried out at 110 °C for 3 h. After cooling to room temperature, it was concentrated under reduced pressure to obtain a cyclic organosilicon quaternary ammonium salt carboxylic acid monomer.

[0040] (3) Under a nitrogen atmosphere, 100 mmol of cyclic organosilicon quaternary ammonium salt carboxylic acid monomer, 500 mmol of thionyl chloride and 5 mL of catalyst N,N-dimethylformamide were added to a reaction flask, and the reaction was carried out at 80 °C for 2 h. After concentration under reduced pressure and drying, 1000 mL of N,N-dimethylacetamide solvent, 420 mmol of ethylenediamine and 700 mmol of triethylamine were added. The reaction was first carried out in an ice-water bath for 1 h, and then at 45 °C for 12 h. After concentration under reduced pressure and drying, organosilicon quaternary ammonium salt hyperbranched polyamide was obtained.

[0041] (4) Under a nitrogen atmosphere, 100 g of PA6 chips, 4 g of organosilicon quaternary ammonium salt hyperbranched polyamide and 0.2 g of antioxidant 2,6-di-tert-butyl-4-methylphenol were added to a spinning machine, and melt blending was carried out at 235 °C. Then, spinning was carried out at 255 °C, and then the fibers were drawn and heat-set through a hot roll drawing machine, where the draw ratio was 5 times and the heat-setting temperature was 110 °C, to obtain a high-strength polyamide fiber composite material.

[0042] Example 3

[0043] (1) Under a nitrogen atmosphere, 80 mmol of 4-vinylpyridine and 400 mL of acetonitrile solvent were added to a reaction flask. After stirring evenly, 96 mmol of 16-bromohexadecanoic acid was added, and the reaction was carried out at 65 °C for 16 h. After cooling to room temperature, concentration under reduced pressure and column chromatography separation (ethyl acetate / petroleum ether = 1:10) were carried out, and the organic phase was concentrated and dried to obtain an alkenyl quaternary ammonium salt monomer.

[0044] (2) Under a nitrogen atmosphere, 70 mmol of 2,4,6,8-tetramethylcyclotetrasiloxane, 0.28 mmol of chloroplatinic acid and 5660 mL of toluene solvent were added to a reaction flask. After stirring evenly, 91 mmol of alkenyl quaternary ammonium salt intermediate was added, and the reaction was carried out at 110 °C for 3 h. After cooling to room temperature, concentration under reduced pressure was carried out to obtain a cyclic organosilicon quaternary ammonium salt carboxylic acid monomer.

[0045] (3) Under a nitrogen atmosphere, 55 mmol of cyclic organosilicon quaternary ammonium salt carboxylic acid monomer, 440 mmol of thionyl chloride and 2.75 mL of catalyst N,N-dimethylformamide were added to a reaction flask, and the reaction was carried out at 80 °C for 2 h. After concentration under reduced pressure and drying, 825 mL of N,N-dimethylacetamide solvent, 330 mmol of ethylenediamine and 550 mmol of triethylamine were added. The reaction was first carried out in an ice-water bath for 3 h, and then at 30 °C for 24 h. After concentration under reduced pressure and drying, organosilicon quaternary ammonium salt hyperbranched polyamide was obtained.

[0046] (4) Under a nitrogen atmosphere, 100 g of PA6 chips, 6 g of organosilicon quaternary ammonium hyperbranched polyamide, and 0.5 g of antioxidant 2,6-di-tert-butyl-4-methylphenol were added to a spinning machine, melt-blended at 220 °C, then spun at 240 °C, and then the fibers were drawn and heat-set through a hot-roll drawing machine, where the draw ratio was 3 times and the heat-setting temperature was 100 °C, to obtain a high-strength polyamide fiber composite material.

[0047] Example 4

[0048] (1) Under a nitrogen atmosphere, 100 mmol of 4-vinylpyridine and 385 mL of acetonitrile solvent were added to a reaction flask. After stirring evenly, 108 mmol of 16-bromohexadecanoic acid was added, and the reaction was carried out at 75 °C for 15 h. After cooling to room temperature, it was concentrated under reduced pressure, and column chromatography separation (ethyl acetate / petroleum ether = 1:10) was carried out. The organic phase was concentrated and dried to obtain an alkenyl quaternary ammonium salt monomer.

[0049] (2) Under a nitrogen atmosphere, 85 mmol of 2,4,6,8-tetramethylcyclotetrasiloxane, 0.272 mmol of chloroplatinic acid, and 578 mL of toluene solvent were added to a reaction flask. After stirring evenly, 103.5 mmol of alkenyl quaternary ammonium salt intermediate was added, and the reaction was carried out at 105 °C for 5 h. After cooling to room temperature, it was concentrated under reduced pressure to obtain a cyclic organosilicon quaternary ammonium salt carboxylic acid monomer.

[0050] (3) Under a nitrogen atmosphere, 70 mmol of cyclic organosilicon quaternary ammonium salt carboxylic acid monomer, 438 mmol of thionyl chloride, and 4.75 mL of catalyst N,N-dimethylformamide were added to a reaction flask, and the reaction was carried out at 70 °C for 3 h. After concentration under reduced pressure and drying, 875 mL of N,N-dimethylacetamide solvent, 340 mmol of ethylenediamine, and 605 mmol of triethylamine were added. First, the reaction was carried out in an ice-water bath for 2 h, and then the reaction was carried out at 40 °C for 18 h. After concentration under reduced pressure and drying, an organosilicon quaternary ammonium hyperbranched polyamide was obtained.

[0051] (4) Under a nitrogen atmosphere, 100 g of PA6 chips, 8 g of organosilicon quaternary ammonium hyperbranched polyamide, and 0.3 g of antioxidant 2,6-di-tert-butyl-4-methylphenol were added to a spinning machine, melt-blended at 230 °C, then spun at 250 °C, and then the fibers were drawn and heat-set through a hot-roll drawing machine, where the draw ratio was 4 times and the heat-setting temperature was 105 °C, to obtain a high-strength polyamide fiber composite material.

[0052] Example 5

[0053] (1) Under a nitrogen atmosphere, 35 mmol of 4-vinylpyridine and 125 mL of acetonitrile solvent were added to a reaction flask. After stirring evenly, 37.8 mmol of 16-bromohexadecanoic acid was added, and the reaction was carried out at 75 °C for 10 h. After cooling to room temperature, it was concentrated under reduced pressure, and separated by column chromatography (ethyl acetate / petroleum ether = 1:10). The organic phase was concentrated and dried to obtain an alkenyl quaternary ammonium salt monomer.

[0054] (2) Under a nitrogen atmosphere, 30 mmol of 2,4,6,8-tetramethylcyclotetrasiloxane, 0.105 mmol of chloroplatinic acid and 195 mL of toluene solvent were added to a reaction flask. After stirring evenly, 36.5 mmol of alkenyl quaternary ammonium salt intermediate was added, and the reaction was carried out at 100 °C for 5 h. After cooling to room temperature, it was concentrated under reduced pressure to obtain a cyclic organosilicon quaternary ammonium salt carboxylic acid monomer.

[0055] (3) Under a nitrogen atmosphere, 20 mmol of cyclic organosilicon quaternary ammonium salt carboxylic acid monomer, 135 mmol of thionyl chloride and 1.4 mL of catalyst N,N-dimethylformamide were added to a reaction flask, and the reaction was carried out at 75 °C for 4 h. After concentration under reduced pressure and drying, 270 mL of N,N-dimethylacetamide solvent, 102 mmol of ethylenediamine and 170 mmol of triethylamine were added. The reaction was first carried out in an ice-water bath for 2 h, and then at 45 °C for 16 h. After concentration under reduced pressure and drying, an organosilicon quaternary ammonium salt hyperbranched polyamide was obtained.

[0056] (4) Under a nitrogen atmosphere, 100 g of PA6 chips, 10 g of organosilicon quaternary ammonium salt hyperbranched polyamide and 0.3 g of antioxidant 2,6-di-tert-butyl-4-methylphenol were added to a spinning machine, and melt-blended at 230 °C. Then, spinning was carried out at 245 °C, and then the fibers were drawn and heat-set through a hot roll drawing machine, where the draw ratio was 4 times and the heat-setting temperature was 110 °C to obtain a high-strength polyamide fiber composite material.

[0057] Comparative Example 1

[0058] (1) Under a nitrogen atmosphere, 40 mmol of 2,4,6,8-tetramethylcyclotetrasiloxane, 0.12 mmol of chloroplatinic acid and 280 mL of toluene solvent were added to a reaction flask. After stirring evenly, 48 mmol of 16-heptadecenoic acid (structural formula is CAS No. is 65119-97-3) was added, and the reaction was carried out at 105 °C for 4 h. After cooling to room temperature, it was concentrated under reduced pressure to obtain a cyclic organosilicon carboxylic acid monomer.

[0059] (2) Under a nitrogen atmosphere, 35 mmol of cyclic organosilicon carboxylic acid monomer, 210 mmol of thionyl chloride, and 2.1 mL of catalyst N,N-dimethylformamide were added to the reaction flask, and the reaction was carried out at 75 °C for 3 h. After concentration under reduced pressure and drying, 420 mL of N,N-dimethylacetamide solvent, 175 mmol of ethylenediamine, and 300 mmol of triethylamine were added. The reaction was first carried out in an ice-water bath for 2 h, and then at 40 °C for 16 h. After concentration under reduced pressure and drying, organosilicon hyperbranched polyamide was obtained.

[0060] (3) Under a nitrogen atmosphere, 100 g of PA6 chips, 2 g of organosilicon hyperbranched polyamide, and 0.4 g of antioxidant 2,6-di-tert-butyl-4-methylphenol were added to the spinning machine, and melt blending was carried out at 225 °C. Then, spinning was carried out at 250 °C. Subsequently, the fibers were drawn and heat-set through a hot roll drawing machine, with a draw ratio of 4 times and a heat-setting temperature of 105 °C, to obtain a polyamide fiber composite material.

[0061] Comparative Example 2

[0062] (1) Under a nitrogen atmosphere, 35 mmol of pyromellitic acid (CAS No. 89-05-4, structural formula )), 210 mmol of thionyl chloride, and 2.1 mL of catalyst N,N-dimethylformamide were added to the reaction flask, and the reaction was carried out at 75 °C for 3 h. After concentration under reduced pressure and drying, 420 mL of N,N-dimethylacetamide solvent, 175 mmol of ethylenediamine, and 300 mmol of triethylamine were added. The reaction was first carried out in an ice-water bath for 2 h, and then at 40 °C for 16 h. After concentration under reduced pressure and drying, hyperbranched polyamide was obtained.

[0063] (2) Under a nitrogen atmosphere, 100 g of PA6 chips, 2 g of hyperbranched polyamide, and 0.4 g of antioxidant 2,6-di-tert-butyl-4-methylphenol were added to the spinning machine, and melt blending was carried out at 225 °C. Then, spinning was carried out at 250 °C. Subsequently, the fibers were drawn and heat-set through a hot roll drawing machine, with a draw ratio of 4 times and a heat-setting temperature of 105 °C, to obtain a polyamide fiber composite material.

[0064] Comparative Example 3

[0065] Under a nitrogen atmosphere, 100 g of PA6 chips and 0.4 g of antioxidant 2,6-di-tert-butyl-4-methylphenol were added to the spinning machine, and melt blending was carried out at 225 °C. Then, spinning was carried out at 250 °C. Subsequently, the fibers were drawn and heat-set through a hot roll drawing machine, with a draw ratio of 4 times and a heat-setting temperature of 105 °C, to obtain a polyamide fiber material.

[0066] Antibacterial performance test: Escherichia coli, Staphylococcus aureus and Candida albicans were used as test strains for antibacterial performance test; the fibers sterilized by ultraviolet irradiation were added to the bacterial suspension of 10 6 CFU / mL, shaken at room temperature for 2 h, 0.2 mL of the bacterial suspension was taken and placed in PBS buffer, then 0.1 mL of the bacterial solution was taken and coated on the surface of the agar medium, placed in a constant temperature and humidity incubator, and cultured at 37 °C for 24 h. After culturing, viable bacteria counting was carried out to calculate the antibacterial rate, and the polyamide fiber material of Comparative Example 3 was used as the blank group. Antibacterial rate = (N 0 -N 1 ) / N 0 ×100%, N 1 is the number of bacteria after culturing in the experimental group, N 0 is the number of bacteria in the blank group.

[0067] Table 1 Antibacterial performance test

[0068]

[0069]

[0070] It can be seen from the test results in the above table that with the increase of the content of organosilicon quaternary ammonium salt hyperbranched polyamide, the antibacterial performance of the polyamide fiber composite gradually increases. In Example 4, the antibacterial rates against Escherichia coli, Staphylococcus aureus and Candida albicans reach 99.9%, 97.8% and 96.6% respectively. This is because the quaternary ammonium salt structure and amide structure in the organosilicon quaternary ammonium salt hyperbranched polyamide are hydrophilic, and the alkyl long chain is hydrophobic. This hydrophilic-hydrophobic combination enables them to form a stable structure in aqueous solution, which helps the quaternary ammonium salt molecules to penetrate the bacterial cell membrane, interact with the cell membranes of bacteria such as Escherichia coli, change the cell membrane permeability, and disrupt the bacterial metabolic process, thus playing a bactericidal role. Quaternary ammonium salt antibacterial structures are not contained in Comparative Examples 1-3, and they do not have antibacterial performance.

[0071] Mechanical property test: The fracture property of the polyamide fiber was tested by an electronic single fiber strength tester, with a clamping distance of 25 cm, a tensile speed of 100 cm / min, and a pre-tension of 150 cN.

[0072] Table 2 Mechanical property test

[0073]

[0074] As can be seen from the test results in the above table, with the increase in the content of organosilicon quaternary ammonium salt hyperbranched polyamide, the mechanical properties of the nylon fiber composite gradually increase. The tear strength of Example 5 reaches 4.80 cN / dtex, indicating that the prepared nylon fiber has a stronger tensile force at the same linear density and has the characteristic of high strength. This is because on the one hand, the organosilicon quaternary ammonium salt hyperbranched polyamide contains a polyamide structure, which is similar and compatible with PA6, and the two can be well melt-blended and spun. The hyperbranched polyamide has a three-dimensional branched molecular chain, which forms physical chain entanglements with the PA6 molecular chain to form a crosslinked network, which is beneficial to improving the breaking strength of the nylon fiber. On the other hand, the cyclic organosilicon structure in the organosilicon quaternary ammonium salt hyperbranched polyamide has a silicon-oxygen bond with a relatively high bond energy, which can absorb more energy when subjected to impact. And due to the relatively large network structure and cavity structure of the hyperbranched polymer, it has a relatively high crosslinking density. When the hyperbranched polymer is dispersed as a dispersion in the PA6 matrix, it can better disperse and transfer stress when subjected to external forces, avoiding material damage caused by stress concentration, thereby playing a role in enhancing and toughening the nylon fiber. In Comparative Example 1 and Comparative Example 2, there is no organosilicon but contains hyperbranched polyamide, and it has a certain impact strength; in Comparative Example 3, there is no organosilicon and hyperbranched polyamide, and the mechanical properties are the worst.

[0075] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a high-strength nylon fiber composite material, characterized in that: The preparation method is carried out according to the following steps: Step (1), under a nitrogen atmosphere, add a cyclic organosilicon quaternary ammonium salt carboxylic acid monomer, thionyl chloride and a catalyst N,N-dimethylformamide into a reaction flask, react at 70-80° C. for 2-4 hours, concentrate under reduced pressure, and after drying, add N,N-dimethylacetamide solvent and ethylenediamine and triethylamine, first react in an ice-water bath for 1-3 hours, then react at 30-45° C. for 12-24 hours, concentrate under reduced pressure, and obtain an organosilicon quaternary ammonium salt hyperbranched polyamide after drying; Step (2), under a nitrogen atmosphere, adding 100 parts by weight of PA6 chips, 2-10 parts of organosilicon quaternary ammonium salt hyperbranched polyamide and 0.2-0.5 parts of antioxidant into a spinning machine, melt blending at 220-235° C., then spinning at 240-255° C., and then stretching and heat-setting the fibers through a hot roller stretching machine to obtain a high-strength nylon fiber composite material.

2. The method for preparing a high-strength nylon fiber composite material according to claim 1, characterized in that: In the step (1), the molar ratio of the cyclic organosilicon quaternary ammonium salt carboxylic acid monomer, thionyl chloride, ethylenediamine and triethylamine is 1:5-8:4.2-6:7-10.

3. The method for preparing a high-strength nylon fiber composite material according to claim 1, characterized in that: The antioxidant in step (2) is 2,6-di-tert-butyl-4-methylphenol.

4. The method for preparing a high-strength nylon fiber composite material according to claim 1, characterized in that: The stretching multiple in step (2) is 3-5 times, and the heat setting temperature is 100-110°C.

5. The method for preparing a high-strength nylon fiber composite material according to claim 1, characterized in that: The preparation method of the cyclic organosilicon quaternary ammonium salt carboxylic acid monomer in step (1) is carried out according to the following steps: Step S1, under a nitrogen atmosphere, add 4-vinylpyridine and acetonitrile solvent to a reaction flask, stir evenly, add 16-bromohexadecanoic acid, stir to react, and after the reaction is completed, cool to room temperature, concentrate under reduced pressure, separate by column chromatography, concentrate the organic phase, and dry to obtain an olefinic quaternary ammonium salt monomer; Step S2, under a nitrogen atmosphere, add 2,4,6,8-tetramethylcyclotetrasiloxane, chloroplatinic acid and toluene solvent into a reaction flask, stir evenly, add the alkenyl quaternary ammonium salt intermediate, stir to react, and after the reaction is completed, cool to room temperature, and concentrate under reduced pressure to obtain a cyclic organosilicon quaternary ammonium salt carboxylic acid monomer.

6. The method for preparing a high-strength nylon fiber composite material according to claim 5, characterized in that: In the step S1, the ratio of 4-vinylpyridine to 16-bromohexadecanoic acid is 1:1.05-1.

2.

7. The method for preparing a high-strength nylon fiber composite material according to claim 5, characterized in that: In step S1, the reaction temperature is 65-80° C. and the reaction time is 8-16 h.

8. The method for preparing a high-strength nylon fiber composite material according to claim 5, characterized in that: In the step S2, the molar ratio of 2,4,6,8-tetramethylcyclotetrasiloxane, chloroplatinic acid and alkenyl quaternary ammonium salt intermediate is 1:0.002-0.004:1.1-1.

3.

9. The method for preparing a high-strength nylon fiber composite material according to claim 5, characterized in that: In step S2, the reaction temperature is 95-110° C. and the reaction time is 3-5 h.

10. A high-strength nylon fiber composite material, characterized in that: Obtained by the preparation method according to any one of claims 1 to 9.

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