Antibacterial halogen-free flame-retardant reinforced crosslinked polyethylene composite fiber and preparation method thereof

Abstract

The application relates to the field of polyethylene composite fibers, and discloses an antibacterial halogen-free flame-retardant reinforced crosslinked polyethylene composite fiber and a preparation method, wherein the composite fiber is prepared from linear low-density polyethylene resin, modified magnesium hydroxide, silver-loaded zirconium phosphate inorganic antibacterial agent, tetra[beta-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester antioxidant, dicumyl peroxide crosslinking agent, hydrogenated castor oil dispersant and industrial white oil solvent; and the modified magnesium hydroxide is prepared from magnesium hydroxide, deionized water, stearic acid and a sodium hydroxide solution. The composite fiber has good mechanical properties, antibacterial property and flame retardancy.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polyethylene composite fibers, in particular to an antibacterial halogen-free flame-retardant reinforced crosslinked polyethylene composite fiber and a preparation method thereof. BACKGROUND

[0002] Polyethylene fiber (polyethylene fiber) is a fiber material obtained by melt spinning of polyethylene, including staple fiber and filament. The mechanical strength of the fiber can be adjusted by the spinning process parameters, and the wet strength and elongation are the same as the dry state. Polyethylene fiber has the advantages of high strength, low density, good insulation, etc., and is mainly used for producing various industrial textiles, especially filter materials, tarpaulins and mesh belts and other products.

[0003] The patent with publication number CN119980499B discloses a preparation method of cool polyethylene fiber, comprising the following steps: step 1, preparation of modifier: S1, weigh the magnesium silicide nano powder and disperse it in ethanol solution, then add the epoxy silane coupling agent, water bath reflux treatment, then centrifuge, rinse and dry to obtain product A; S2, weigh 5-amino-2-mercaptobenzimidazole and dissolve it in tetrahydrofuran, then add product A, water bath reflux treatment again, centrifuge, rinse and dry after the reaction is completed to obtain product B; S3, weigh 4-vinyl guaiacol and add it to N,N-dimethylformamide, stir uniformly, then add product B, stir uniformly, then add a photoinitiator, react under ultraviolet light, rinse and dry the product after the reaction is completed to obtain the modifier; step 2, preparation of modified resin: add antioxidants and nucleating agents to an organic solvent, stir uniformly, then add high-density polyethylene resin, stir and heat until dissolved, then add the modifier, stir again, then remove the solvent under reduced pressure, dry to obtain the modified polyethylene resin; step 3, melt spinning: add the modified polyethylene resin into a double screw machine for melting, then extrude through a spinning machine to obtain cool polyethylene fiber. However, this scheme still has some deficiencies: the fiber does not have antibacterial function during use, is easy to cause the breeding of microorganisms, and has poor flame retardancy. SUMMARY

[0004] The purpose of the present application is to provide an antibacterial halogen-free flame-retardant reinforced crosslinked polyethylene composite fiber and a preparation method thereof to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present application provides the following technical solutions: an antibacterial halogen-free flame-retardant reinforced crosslinked polyethylene composite fiber, which is prepared from linear low-density polyethylene resin, modified magnesium hydroxide, silver-loaded zirconium phosphate inorganic antibacterial agent, tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester antioxidant, dicumyl peroxide crosslinking agent, hydrogenated castor oil dispersant and industrial white oil solvent; the modified magnesium hydroxide is prepared from magnesium hydroxide, deionized water, stearic acid and sodium hydroxide solution.

[0006] Further, the linear low-density polyethylene resin has a melt index of 20-30 g / 10 min (190℃ / 2.16 kg).

[0007] Further, the magnesium hydroxide has a particle size of 0.8-1.2 μm.

[0008] Further, the silver-loaded zirconium phosphate inorganic antibacterial agent has a particle size of 0.1-0.3 μm and a silver content of 4.0-4.2%.

[0009] Further, a preparation method of the antibacterial halogen-free flame-retardant reinforced crosslinked polyethylene composite fiber comprises the following steps:

[0010] (1) magnesium hydroxide is added to deionized water, stirred at a speed of 800-1000 rpm for 20-30 minutes, and then treated by ultrasonic waves with a power of 200-400 W for 10-15 minutes to obtain a suspension with a solid content of 15-20%; stearic acid and a sodium hydroxide solution with a mass fraction of 5-10% are mixed in a mass ratio of 1:(3-5), stirred at a speed of 200-300 rpm at a temperature of 70-75℃ for 15-20 minutes to obtain a sodium stearate solution; the sodium stearate solution is slowly added to the magnesium hydroxide suspension at a temperature of 75-85℃ within 30-40 minutes, while continuously stirring at a speed of 400-500 rpm; after the addition is completed, the stirring is continued at a temperature of 80-85℃ for 2-3 hours; after filtration, washing with deionized water for 3-5 times, and drying in a vacuum drying oven at 100-105℃ for 4-6 hours, the modified magnesium hydroxide is obtained;

[0011] (2) linear low-density polyethylene resin, modified magnesium hydroxide, silver-loaded zirconium phosphate inorganic antibacterial agent and tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester antioxidant are placed in a mixer and mixed at a speed of 300-400 rpm at a temperature of 80-85℃ for 15-20 minutes; then, a double-screw extruder is used for melt extrusion granulation to obtain a flame-retardant antibacterial master batch;

[0012] (3) drying the linear low density polyethylene resin and the flame-retardant antibacterial master batch obtained in step (2) at 60-65 DEG C for 1-2 hours, mixing at room temperature in a mixer at a rotating speed of 200-300 rpm for 10-15 minutes, and then melt spinning to obtain the primary fiber; the melt spinning is carried out under the following conditions: spinneret aperture 0.3-0.4 mm, spinning speed 800-1000 m / min, and spinning temperature 190-200 DEG C;

[0013] (4) adding dicumyl peroxide crosslinking agent and hydrogenated castor oil dispersant into industrial white oil solvent with a distillation range of 190-220 DEG C, stirring at 70-75 DEG C at a rotating speed of 300-400 rpm for 60-70 minutes to obtain an impregnation solution;

[0014] (5) dipping the primary fiber obtained in step (3) in the impregnation solution at 50-60 DEG C for 4-5 hours;

[0015] (6) grading heat treatment of the dipped fiber through a heat setting machine, the first zone temperature being 110-115 DEG C, the first zone treatment time being 90-100 seconds, the second zone temperature being 175-180 DEG C, the second zone treatment time being 120-130 seconds, the third zone temperature being 150-155 DEG C, and the third zone treatment time being 60-70 seconds, to obtain the composite fiber.

[0016] Further, the mass ratio of the sodium stearate solution and the magnesium hydroxide suspension in step (1) is 1:(8-12).

[0017] Further, the mass ratio of the linear low density polyethylene resin, the modified magnesium hydroxide, the silver-loaded zirconium phosphate inorganic antibacterial agent, and the pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant in step (2) is 60:(33-37):(4-6):(0.4-0.6).

[0018] Further, the temperature of the double-screw extruder in step (2) is set as follows: the first zone 150-155 DEG C, the second zone 170-175 DEG C, the third zone 180-185 DEG C, and the die head 185-190 DEG C, the screw rotating speed is 250-300 rpm, and the length-diameter ratio is 39-41:1.

[0019] Further, the mass ratio of the linear low density polyethylene resin and the flame-retardant antibacterial master batch in step (3) is (30-40):(20-30).

[0020] Further, the mass ratio of the dicumyl peroxide crosslinking agent, the hydrogenated castor oil dispersant, and the industrial white oil solvent in step (4) is (4-6):(0.5-1.0):(93-95).

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1. Stearic acid reacts with sodium hydroxide to form sodium stearate, which forms an organic coating layer on the surface of magnesium hydroxide, improving its dispersibility and compatibility in the polyethylene matrix; silver-loaded zirconium phosphate inorganic antibacterial agent is used to slowly release silver ions through ion exchange, achieving antibacterial performance; pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant is used to prevent thermal oxidative degradation during processing by providing hydrogen atoms to terminate the radical oxidation reaction of the polyethylene molecular chain; dicumyl peroxide crosslinking agent is used to generate free radicals under heating conditions, which extract hydrogen atoms from the polyethylene molecular chain to form macromolecular radicals, and adjacent macromolecular radicals combine through carbon-carbon bonds to form a three-dimensional network crosslinked structure; hydrogenated castor oil dispersant is used to reduce the solid-liquid interface energy through its amphiphilic molecular structure, making the dicumyl peroxide crosslinking agent more uniformly dispersed in the industrial white oil solvent; and the crosslinking reaction is promoted through a heat treatment process, so that the composite fiber has good mechanical properties, antibacterial properties and flame retardancy. DETAILED DESCRIPTION

[0023] The following examples are provided to better further understand the present application and are not limited to the best mode, and do not limit the content and scope of protection of the present application. Any person under the inspiration of the present application or the combination of the present application with other prior art features will fall within the scope of protection of the present application.

[0024] An antibacterial halogen-free flame-retardant reinforced crosslinked polyethylene composite fiber, the composite fiber is prepared from linear low density polyethylene resin, modified magnesium hydroxide, silver-loaded zirconium phosphate inorganic antibacterial agent, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant, dicumyl peroxide crosslinking agent, hydrogenated castor oil dispersant and industrial white oil solvent; the modified magnesium hydroxide is prepared from magnesium hydroxide, deionized water, stearic acid and sodium hydroxide solution.

[0025] The specific experimental steps or conditions are not specified in the examples, which can be carried out according to the conventional experimental steps described in the literature in the art or the operation or conditions. The reagents or instruments used are not specified by the manufacturer, which are conventional reagent products that can be obtained by market purchase. EXAMPLE

[0026] (1) magnesium hydroxide with a particle size of 0.8 μm was added into deionized water, stirred at a speed of 800 rpm for 20 minutes, and then treated by ultrasonic with a power of 200 W for 10 minutes to obtain a suspension with a solid content of 15%; stearic acid and a 5% sodium hydroxide solution were mixed in a mass ratio of 1:3, stirred at a speed of 200 rpm at a temperature of 70 °C for 15 minutes to obtain a sodium stearate solution; the sodium stearate solution was slowly added into the magnesium hydroxide suspension at a temperature of 75 °C within 30 minutes, while continuously stirring at a speed of 400 rpm; after the addition was completed, the stirring was continued at a temperature of 80 °C for 2 hours; after filtration, washing with deionized water for 3 times, and drying in a vacuum drying oven at 100 °C for 4 hours, modified magnesium hydroxide was obtained;

[0027] The mass ratio of the sodium stearate solution to the magnesium hydroxide suspension is 1:8.

[0028] (2) linear low density polyethylene resin with a melt index of 20 g / 10 min (190 °C / 2.16 kg), modified magnesium hydroxide, silver-containing zirconium phosphate inorganic antibacterial agent with a particle size of 0.1 μm and a silver content of 4.0%, and pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant were placed in a mixer and mixed at a speed of 300 rpm at a temperature of 80 °C for 15 minutes; then, melt extrusion granulation was performed by using a twin-screw extruder, to obtain a flame-retardant antibacterial master batch. The temperature of the twin-screw extruder was set as follows: zone 1, 150 °C; zone 2, 170 °C; zone 3, 180 °C; die head, 185 °C; screw speed, 250 rpm; length-diameter ratio, 39:1.

[0029] The mass ratio of the linear low density polyethylene resin, the modified magnesium hydroxide, the silver-containing zirconium phosphate inorganic antibacterial agent, and the pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant is 60:33:4:0.4.

[0030] (3) linear low density polyethylene resin with a melt index of 20 g / 10 min (190 °C / 2.16 kg) and the flame-retardant antibacterial master batch obtained in step (2) were dried at 60 °C for 1 hour, then mixed in a mixer at a speed of 200 rpm at room temperature for 10 minutes, and then melt spinning was performed to obtain nascent fibers. The conditions of the melt spinning were as follows: spinneret hole diameter, 0.3 mm; spinning rate, 800 m / min; spinning temperature, 190 °C.

[0031] The mass ratio of the linear low density polyethylene resin and the flame-retardant antibacterial master batch is 30:20.

[0032] (4) dicumyl peroxide crosslinking agent and hydrogenated castor oil dispersant were added into technical white oil solvent with a distillation range of 190 °C, stirred at a speed of 300 rpm at a temperature of 70 °C for 60 minutes to obtain an impregnation solution;

[0033] The mass ratio of the dicumyl peroxide crosslinking agent, the hydrogenated castor oil dispersant, and the technical white oil solvent is 4:0.5:93.

[0034] (5) The primary fiber obtained in step (3) is dipped in the dipping solution at 50°C for 4 hours;

[0035] (6) The dipped fiber is subjected to graded heat treatment by a heat setting machine, the first zone temperature is 110°C, the treatment time is 90 seconds, the second zone temperature is 175°C, the treatment time is 120 seconds, the third zone temperature is 150°C, and the treatment time is 60 seconds, to obtain the composite fiber. Example

[0036] (1) Magnesium hydroxide with a particle size of 1.0 μm is added to deionized water, stirred at a speed of 900 rpm for 25 minutes, and then treated by ultrasonic power of 300 W for 12.5 minutes to obtain a suspension with a solid content of 17.5%; stearic acid and a sodium hydroxide solution with a mass fraction of 7.5% are mixed at a mass ratio of 1:4, stirred at a speed of 250 rpm at a temperature of 72.5°C for 17.5 minutes to obtain a sodium stearate solution; at a temperature of 80°C, the sodium stearate solution is slowly added to the magnesium hydroxide suspension within 35 minutes, while continuously stirring at a speed of 450 rpm; after the addition is completed, the stirring is continued at a temperature of 82.5°C for 2.5 hours; after filtration, washing with deionized water for 4 times, and drying in a vacuum drying oven at 102.5°C for 5 hours, the modified magnesium hydroxide is obtained.

[0037] The mass ratio of the sodium stearate solution and the magnesium hydroxide suspension is 1:10.

[0038] (2) Linear low-density polyethylene resin with a melt index of 25 g / 10 min (190°C / 2.16 kg), modified magnesium hydroxide, silver-loaded zirconium phosphate inorganic antibacterial agent with a particle size of 0.2 μm and a silver content of 4.1%, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant are placed in a mixer, mixed at a speed of 350 rpm at a temperature of 82.5°C for 17.5 minutes; then melt extrusion granulation is performed by using a twin-screw extruder, to obtain a flame-retardant antibacterial masterbatch. The temperature of the twin-screw extruder is set as follows: the first zone is 152.5°C, the second zone is 172.5°C, the third zone is 182.5°C, the die head is 187.5°C, the screw rotation speed is 275 rpm, and the length-diameter ratio is 40:1.

[0039] The mass ratio of the linear low-density polyethylene resin, the modified magnesium hydroxide, the silver-loaded zirconium phosphate inorganic antibacterial agent, and the pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant is 60:35:5:0.5.

[0040] (3) Linear low density polyethylene resin with melt index of 25 g / 10 min (190 °C / 2.16 kg) was dried at 62.5 °C for 1.5 hours, and then mixed with the flame-retardant antibacterial masterbatch obtained in step (2) in a mixer at room temperature for 12.5 minutes at a rotation speed of 250 rpm, and then melt spinning was performed to obtain the primary fibers. The melt spinning conditions were: spinneret hole diameter 0.35 mm, spinning rate 900 m / min, and spinning temperature 195 °C.

[0041] The mass ratio of the linear low density polyethylene resin and the flame-retardant antibacterial masterbatch was 35:25.

[0042] (4) The dicumyl peroxide crosslinking agent and the hydrogenated castor oil dispersant were added to the technical white oil solvent with a distillation range of 200 °C, and stirring was performed at a temperature of 72.5 °C and a rotation speed of 350 rpm for 65 minutes to obtain an impregnation solution;

[0043] The mass ratio of the dicumyl peroxide crosslinking agent, the hydrogenated castor oil dispersant, and the technical white oil solvent was 5:0.75:94.

[0044] (5) The primary fibers obtained in step (3) were immersed in the impregnation solution at 55 °C for 4.5 hours;

[0045] (6) The immersed fibers were subjected to staged heat treatment by a heat setting machine, the first zone temperature was 112.5 °C, the treatment time was 95 seconds, the second zone temperature was 177.5 °C, the treatment time was 125 seconds, the third zone temperature was 152.5 °C, and the treatment time was 65 seconds, to obtain the composite fibers. Example

[0046] (1) Magnesium hydroxide with a particle size of 1.2 μm was added to deionized water, and stirring was performed at a rotation speed of 1000 rpm for 30 minutes, and then ultrasonic treatment was performed at a power of 400 W for 15 minutes to obtain a suspension with a solid content of 20%; stearic acid and a 10% sodium hydroxide solution were mixed at a mass ratio of 1:5, and stirring was performed at a temperature of 75 °C and a rotation speed of 300 rpm for 20 minutes to obtain a sodium stearate solution; the sodium stearate solution was slowly added to the magnesium hydroxide suspension at a temperature of 85 °C within 40 minutes, while stirring was continuously performed at a rotation speed of 500 rpm, after the addition was completed, stirring was continued at a temperature of 85 °C for 3 hours, and then filtration, washing with deionized water for 5 times, and drying in a vacuum drying oven at 105 °C for 6 hours were performed to obtain modified magnesium hydroxide;

[0047] The mass ratio of the sodium stearate solution and the magnesium hydroxide suspension was 1:12.

[0048] (2) Linear low density polyethylene resin with melt index of 30 g / 10 min (190°C / 2.16 kg), modified magnesium hydroxide, silver-containing zirconium phosphate inorganic antibacterial agent with particle size of 0.3 μm and silver content of 4.2%, and pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant are put into a mixer and mixed at a temperature of 85°C and a rotating speed of 400 rpm for 20 minutes; then, melt extrusion granulation is carried out by using a twin-screw extruder, and the temperature of the twin-screw extruder is set as follows: 155°C for the first zone, 175°C for the second zone, 185°C for the third zone, and 190°C for the die head, and the rotating speed of the screw is 300 rpm and the length-diameter ratio is 41:1; thus, a flame-retardant antibacterial master batch is obtained.

[0049] The mass ratio of the linear low density polyethylene resin, the modified magnesium hydroxide, the silver-containing zirconium phosphate inorganic antibacterial agent, and the pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant is 60:37:6:0.6.

[0050] (3) Linear low density polyethylene resin with melt index of 30 g / 10 min (190°C / 2.16 kg) and the flame-retardant antibacterial master batch obtained in step (2) are dried at 65°C for 2 hours, and then mixed in a mixer at room temperature and a rotating speed of 300 rpm for 15 minutes, and then melt spinning is carried out, thus obtaining a primary fiber. The melt spinning is carried out under the following conditions: the spinneret aperture is 0.4 mm, the spinning rate is 1000 m / min, and the spinning temperature is 200°C.

[0051] The mass ratio of the linear low density polyethylene resin and the flame-retardant antibacterial master batch is 40:30.

[0052] (4) The dicumyl peroxide crosslinking agent and the hydrogenated castor oil dispersant are added into the industrial white oil solvent with a distillation range of 220°C, and stirred at a temperature of 75°C and a rotating speed of 400 rpm for 70 minutes, thus obtaining an impregnation solution.

[0053] The mass ratio of the dicumyl peroxide crosslinking agent, the hydrogenated castor oil dispersant, and the industrial white oil solvent is 6:1.0:95.

[0054] (5) The primary fiber obtained in step (3) is impregnated in the impregnation solution at 60°C for 5 hours.

[0055] (6) The impregnated fiber is subjected to hierarchical heat treatment by using a heat setting machine, and the first zone temperature is 115°C, the treatment time is 100 seconds, the second zone temperature is 180°C, the treatment time is 130 seconds, and the third zone temperature is 155°C, the treatment time is 70 seconds, thus obtaining a composite fiber.

[0056] Comparative Example 1

[0057] The difference between Comparative Example 1 and Example 1 is that the magnesium hydroxide is not surface modified.

[0058] Comparative Example 2

[0059] The difference between Comparative Example 2 and Example 1 is only that the silver-loaded zirconium phosphate inorganic antibacterial agent is not added.

[0060] Comparative Example 3

[0061] The difference between Comparative Example 3 and Example 1 is only that the dicumyl peroxide crosslinking agent is not added.

[0062] Comparative Example 4

[0063] The difference between Comparative Example 4 and Example 1 is only that the impregnation treatment and subsequent heat treatment process are not performed, and the as-spun fiber is directly used as the finished fiber.

[0064] The breaking strength and elongation at break test is tested according to GB / T14344-2022. The fiber is woven with plain weave, and the fabric density is 120 ends / 10 cm in the warp direction and 80 ends / 10 cm in the weft direction. Then the Staphylococcus aureus antibacterial property and Escherichia coli antibacterial property are tested according to GB / T20944.3-2008, and the flame retardant property is tested according to GB / T5454-1997.

[0065] The performance analysis results of the examples and comparative examples of the application are shown in the following Table 1.

[0066] Sample Breaking strength (cN / dtex) Elongation at break (%) Limiting oxygen index (%) Staphylococcus aureus antibacterial rate (%) Escherichia coli antibacterial rate (%) Example 1 5.0 28 26 99.6 99.4 Example 2 5.3 32 27 99.7 99.6 Example 3 4.8 29 26 99.5 99.3 Comparative Example 1 3.3 50 25 99.1 98.9 Comparative Example 2 3.8 140 26 No antibacterial property No antibacterial property Comparative Example 3 3.5 200 24 99.1 98.9 Comparative Example 4 3.8 140 25 98.7 98.4

[0067] From the experimental data of the examples and comparative examples, it can be found that the sodium stearate is generated by the reaction of stearic acid and sodium hydroxide, and an organic coating layer is formed on the surface of magnesium hydroxide, which improves the dispersibility and compatibility of magnesium hydroxide in the polyethylene matrix; the silver-loaded zirconium phosphate inorganic antibacterial agent slowly releases silver ions through ion exchange; the dicumyl peroxide crosslinking agent generates free radicals under heating conditions, and these free radicals form macromolecular radicals by taking hydrogen atoms on the polyethylene molecular chain, and adjacent macromolecular radicals are combined to form a three-dimensional network crosslinking structure through carbon-carbon bonds; the hydrogenated castor oil dispersant reduces the solid-liquid interface energy through its amphiphilic molecular structure, ensuring the uniform dispersion of the dicumyl peroxide crosslinking agent in the industrial white oil solvent; and the heat treatment process promotes the crosslinking reaction, so that the composite fiber has good mechanical properties, antibacterial property and flame retardancy.

[0068] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. The embodiments should therefore be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. No reference herein to any prior art is to be taken as an admission that the present application is not entitled to antedate such prior art by virtue of prior application. Any reference to the term "comprising" is to be construed in accordance with the definition of that term provided in the preamble to Article 69 of the European Patent Convention. Any reference to the term "comprising" is to be construed in accordance with the definition of that term provided in the preamble to Article 69 of the European Patent Convention.

Claims

1. An antibacterial halogen-free flame-retardant reinforced crosslinked polyethylene composite fiber, characterized by, The composite fiber is prepared from linear low density polyethylene resin, modified magnesium hydroxide, silver-loaded zirconium phosphate inorganic antibacterial agent, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant, dicumyl peroxide crosslinking agent, hydrogenated castor oil dispersant and industrial white oil solvent; the modified magnesium hydroxide is prepared from magnesium hydroxide, deionized water, stearic acid and sodium hydroxide solution; The preparation method of the composite fiber comprises the following steps: (1) magnesium hydroxide is added into deionized water, stirred at a speed of 800-1000 rpm for 20-30 minutes, and then treated by ultrasonic with a power of 200-400 W for 10-15 minutes to obtain a suspension with a solid content of 15-20%; stearic acid and a sodium hydroxide solution with a mass fraction of 5-10% are mixed at a mass ratio of 1:(3-5), stirred at a speed of 200-300 rpm at a temperature of 70-75 ℃ for 15-20 minutes to obtain a sodium stearate solution; the sodium stearate solution is slowly added into the magnesium hydroxide suspension at a temperature of 75-85 ℃ within 30-40 minutes, while continuously stirring at a speed of 400-500 rpm, after the addition is completed, the stirring is continued at a temperature of 80-85 ℃ for 2-3 hours, and then the modified magnesium hydroxide is obtained by filtration, washing with deionized water for 3-5 times and drying in a vacuum drying oven at 100-105 ℃ for 4-6 hours; (2) linear low density polyethylene resin, modified magnesium hydroxide, silver-loaded zirconium phosphate inorganic antibacterial agent and pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant are placed in a mixer and mixed at a speed of 300-400 rpm at a temperature of 80-85 ℃ for 15-20 minutes; then, melt extrusion granulation is carried out by using a double-screw extruder to obtain a flame-retardant antibacterial master batch; (3) linear low density polyethylene resin and the flame-retardant antibacterial master batch obtained in step (2) are dried at 60-65 ℃ for 1-2 hours, then mixed in a mixer at a speed of 200-300 rpm at room temperature for 10-15 minutes, and then melt spinning is carried out to obtain a nascent fiber; the melt spinning conditions are as follows: spinneret aperture 0.3-0.4 mm, spinning rate 800-1000 m / min, spinning temperature 190-200 ℃; (4) dicumyl peroxide crosslinking agent and hydrogenated castor oil dispersant are added into industrial white oil solvent with a distillation range of 190-220 ℃, and stirred at a speed of 300-400 rpm at a temperature of 70-75 ℃ for 60-70 minutes to obtain an impregnation solution; (5) the nascent fiber obtained in step (3) is immersed in the impregnation solution at 50-60 ℃ for 4-5 hours; (6) the immersed fiber is subjected to hierarchical heat treatment by a heat setting machine, the first zone temperature is 110-115 ℃, the treatment time is 90-100 seconds, the second zone temperature is 175-180 ℃, the treatment time is 120-130 seconds, the third zone temperature is 150-155 ℃, and the treatment time is 60-70 seconds, to obtain the composite fiber.

2. An antibacterial, halogen-free, flame-retardant, reinforced, crosslinked polyethylene composite fiber according to claim 1, characterized in that : The linear low density polyethylene resin has a melt index of 20-30 g / 10 min at a temperature of 190 DEG C and a load of 2.16 kg.

3. An antibacterial, halogen-free, flame-retardant, reinforced, crosslinked polyethylene composite fiber according to claim 2, characterized in that : The magnesium hydroxide has a particle size of 0.8-1.2 µm.

4. An antibacterial, halogen-free, flame-retardant, reinforced, crosslinked polyethylene composite fiber according to claim 3, characterized in that : The silver-loaded zirconium phosphate inorganic antibacterial agent has a particle size of 0.1-0.3 µm and a silver content of 4.0-4.2%.

5. An antibacterial, halogen-free, flame-retardant, reinforced, crosslinked polyethylene composite fiber according to claim 1, characterized in that : The mass ratio of the sodium stearate solution to the magnesium hydroxide suspension in step (1) is 1:(8-12).

6. An antibacterial, halogen-free, flame-retardant, reinforced, crosslinked polyethylene composite fiber according to claim 1, characterized in that : The mass ratio of the linear low density polyethylene resin, the modified magnesium hydroxide, the silver-loaded zirconium phosphate inorganic antibacterial agent and the pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] antioxidant in step (2) is 60:(33-37):(4-6):(0.4-0.6).

7. An antibacterial, halogen-free, flame retardant, reinforced, crosslinked polyethylene composite fiber according to claim 1, characterized in that : The temperature of the twin-screw extruder in step (2) is set as follows: zone 1, 150-155 DEG C; zone 2, 170-175 DEG C; zone 3, 180-185 DEG C; and the head, 185-190 DEG C; the screw rotation speed is 250-300 rpm and the length-diameter ratio is 39-41:

1.

8. An antibacterial, halogen-free, flame-retardant, reinforced, crosslinked polyethylene composite fiber according to claim 1, characterized in that : The mass ratio of the linear low density polyethylene resin to the flame-retardant antibacterial master batch in step (3) is (30-40):(20-30).

9. An antibacterial, halogen-free, flame retardant, reinforced, crosslinked polyethylene composite fiber according to claim 1, characterized in that : The mass ratio of the dicumyl peroxide crosslinking agent, the hydrogenated castor oil dispersant and the industrial white oil solvent in step (4) is (4-6):(0.5-1.0):(93-95).