Ultra-high molecular weight polyethylene fiber and its preparation method and application

Abstract

The present invention relates to the technical field of polymer materials, and discloses ultra-high molecular weight polyethylene fiber and its preparation method and application. The preparation method of the ultra-high molecular weight polyethylene fiber comprises: step 1, swelling ultra-high molecular weight polyethylene, flame retardant and antioxidant in a solvent to obtain a swelling liquid; step 2, mixing, melting and extruding the swelling liquid in a twin-screw extruder to obtain a polymer melt; step 3, sending the polymer melt into a spinning tunnel for drawing to obtain ultra-high molecular weight polyethylene fiber; the feeding port temperature of the twin-screw extruder is 25-40°C, the temperature of the mixing and melting section is 80-180°C; the extrusion port temperature of the twin-screw extruder is 145-170°C; in the spinning tunnel, the spinning tunnel temperature is 75-140°C, and the air volume is 200-800N 3 / h; the drafting frequency of the drafting is 15-30. The ultra-high molecular weight polyethylene fiber provided by the invention has strong flame retardant, anti-aging and mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to ultra-high molecular weight polyethylene fiber and a preparation method and application thereof. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber is widely used in aerospace, automobile shell, ship cabin and wind turbine blades due to its excellent properties such as low specific gravity, high specific strength and specific modulus. Due to its excellent comprehensive performance, the market demand is increasing, and with the rapid development of today's science and technology, ultra-high molecular weight polyethylene fiber has attracted the attention of many researchers.

[0003] UHMWPE fiber is prepared by gel spinning. Its specific strength is more than ten times that of steel wire of the same cross-section, the highest among all fibers, and its specific modulus is second only to carbon fiber. Therefore, it is known as one of the world's three major high-performance fibers together with carbon fiber and aramid. At present, UHMWPE fiber has been used in many fields, such as bulletproof helmets, stab-proof gloves, sports equipment and high-strength cables.

[0004] Although UHMWPE fiber has excellent performance, its flame retardancy is very poor, and its limiting oxygen index is only 17.5, which is flammable. The amount of heat and smoke generated during the combustion process is large, and toxic gases are produced. It also produces molten droplets and causes secondary disasters, which greatly limits its application and development. With the advancement of science and technology and the improvement of people's living standards, people's safety requirements for textiles are gradually increasing. Every year, countless fires are caused by textile fires, which cause serious harm to people's daily life and economic property. Therefore, the research on the flame retardant properties of textiles has also attracted widespread attention. Anti-cut gloves, stab-proof clothing and conveyor belts with flame retardant functions play an important role in protecting users and public safety, which can resist fire and reduce safety hazards. The research, development and application of flame retardant materials are related to my country's economic development, national defense and personnel life safety. At present, with the increasing environmental protection requirements, the application scope of traditional halogen flame retardants such as bromine is restricted to varying degrees, and the flame retardant UHMWPE fiber prepared by the prior art has the disadvantages of poor flame retardant performance, short-lasting flame retardant effect, and reduced mechanical strength of flame retardant UHMWPE fiber after adding flame retardant.

[0005] Therefore, while improving the flame retardant properties of UHMWPE fibers, it also has strong mechanical properties and expands the application scope of flame retardant UHMWPE fibers, which has great practical significance. Summary of the invention

[0006] The purpose of the present invention is to overcome the problem that the prior art needs to add halogen flame retardants such as bromine in the process of preparing ultra-high molecular weight polyethylene fibers, which leads to non-compliance with environmental protection requirements and poor flame retardancy and mechanical properties, and to provide an ultra-high molecular weight polyethylene fiber and a preparation method and application thereof. The ultra-high molecular weight polyethylene fiber (UHMWPE) prepared by the preparation method has the characteristics of strong flame retardancy and high strength and high modulus.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for preparing ultra-high molecular weight polyethylene fiber, characterized in that the preparation method comprises the following steps:

[0008] Step 1, swelling the ultra-high molecular weight polyethylene, the flame retardant and the antioxidant in a solvent to obtain a swelling liquid;

[0009] Step 2, kneading, melting and extruding the swelling liquid in a twin-screw extruder to obtain a polymer melt;

[0010] Step 3, feeding the polymer melt into a spinning tunnel for drawing to obtain ultra-high molecular weight polyethylene fibers;

[0011] The feed port temperature of the twin-screw extruder is 25-40°C, the temperature of the mixing and melting section is 80-180°C; the extrusion port temperature of the twin-screw extruder is 145-170°C;

[0012] In the spinning tunnel, the spinning tunnel temperature is 75-140°C, and the air volume is 200-800N. 3 / h;

[0013] The drafting frequency of the drafting is 15-30.

[0014] The second aspect of the present invention provides an ultra-high molecular weight polyethylene fiber prepared by the above method.

[0015] A third aspect of the present invention provides an application of the above method and / or the above ultra-high molecular weight polyethylene fiber in the field of labor protection products and / or protective products.

[0016] Through the above technical scheme, the ultra-high molecular weight polyethylene fiber provided by the present invention and its preparation method and application obtain the following beneficial effects:

[0017] The UHMWPE fiber preparation method is simple. The temperature of the mixing and melting section is set to 80-180°C, the extrusion port of the twin-screw extruder is set to 145-170°C, the spinning tunnel temperature is set to 75-140°C, and the air volume is set to 200-800N. 3 / h, and the drawing frequency is 15-30, the breaking strength and modulus of the prepared UHMWPE fiber are significantly improved.

[0018] The halogen-free flame retardant added to the UHMWPE fiber is environmentally friendly and can be widely used in various labor protection products, protective tools and other civil and military fields. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] A first aspect of the present invention provides a method for preparing ultra-high molecular weight polyethylene fiber, characterized in that the preparation method comprises the following steps:

[0021] Step 1, swelling the ultra-high molecular weight polyethylene and an additive selected from flame retardants and antioxidants in a solvent to obtain a swelling liquid;

[0022] Step 2, kneading, melting and extruding the swelling liquid in a twin-screw extruder to obtain a polymer melt;

[0023] Step 3, feeding the polymer melt into a spinning tunnel for drawing to obtain polymer fibers;

[0024] The feed port temperature of the twin-screw extruder is 25-40°C, the temperature of the mixing and melting section is 80-180°C; the extrusion port temperature of the twin-screw extruder is 145-170°C;

[0025] In the spinning tunnel, the spinning tunnel temperature is 75-140°C, and the air volume is 200-800N. 3 / h;

[0026] The drafting frequency of the drafting is 15-30.

[0027] In the present invention, ultra-high molecular weight polyethylene, flame retardant and antioxidant are subjected to swelling treatment in a solvent, so that the long chain of ultra-high molecular weight polyethylene can be fully unfolded, and all additives and ultra-high molecular weight polyethylene powder can form a homogeneous system in the solvent, which can effectively shorten the dissolution time of ultra-high molecular weight polyethylene.

[0028] In the present invention, when the feed port temperature of the twin-screw extruder is 25-40°C, the temperature of the mixing and melting section is 80-180°C; the extrusion port temperature of the twin-screw extruder is 145-170°C; and the spinning tunnel temperature is 75-140°C, the air volume is 200-800N 3 / h, the prepared UHMWPE fiber can have stronger mechanical properties and lower moisture content.

[0029] In the present invention, when the drafting frequency is 15-30, the subsequent spinnability can be increased.

[0030] According to the present invention, the mixing and melting section is a plurality of mixing and melting sections.

[0031] Furthermore, the mixing and melting sections are 5-7 mixing and melting sections;

[0032] Among them, the temperature of the first mixing and melting section is 80-90°C, the temperature of the second mixing and melting section is 110-130°C, the temperature of the third mixing and melting section is 145-160°C, the temperature of the fourth mixing and melting section is 160-170°C, the temperature of the fifth mixing and melting section is 160-170°C, the temperature of the sixth mixing and melting section is 160-170°C, and the temperature of the seventh mixing and melting section is 160-170°C.

[0033] In the present invention, when the mixing and melting is divided into 6 mixing and melting sections, and the temperatures of the 6 mixing and melting sections respectively meet the above ranges, the polymer can achieve a better dispersion effect and reduce the dryness rate, so that the dryness rate is not more than 3%.

[0034] In the present invention, the evenness refers to the main line of the yarn or sliver. The uniformity of the thickness or weight of the yarn, sliver or roving in a short axial section is called the evenness rate, also known as evenness uniformity. The evenness rate has a certain influence on the strength of the fiber and will affect the quality of the yarn or fabric during subsequent processing. If the evenness rate is too large, defects will appear and the breakage rate will increase, thereby affecting production.

[0035] According to the present invention, the drafting is a multi-stage drafting, preferably a 3-5-stage drafting;

[0036] Among them, the drafting frequency of the first drafting stage is 15-20, the drafting frequency of the second drafting stage is 20-25, the third drafting frequency is 20-25, the fourth drafting frequency is 25-30, and the fifth drafting frequency is 25-30.

[0037] In the present invention, when the drafting sections are 4-section drafting and the frequencies of the 4-section drafting satisfy the above ranges respectively, the ordered folded chains of the primary fibers can be further arranged longitudinally, thereby increasing the strength of the fibers and reducing the elongation.

[0038] In the present invention, the performance is better when the elongation is in the range of 4.3%-5.3%. If it is too low, the fiber is easy to break, and if it is too high, the strength modulus is poor.

[0039] According to the present invention, the preparation method further comprises: a step of removing the solvent from the polymer melt, and sending the polymer melt from which the solvent has been removed into a spinning tunnel for drawing.

[0040] In the present invention, the solvent is removed from the polymer melt before it enters the spinning tunnel, which can help improve the fiber strength of the polymer melt during the spinning process.

[0041] In the present invention, there is no requirement for the device for removing the solvent, as long as the solvent can be removed efficiently. For example, the device for removing the solvent can be a ring cooling jacket.

[0042] According to the present invention, the conditions for removing the solvent are: temperature of 80-140°C, side blowing temperature of 90-120°C, side blowing air volume of 400-800N 3 / h.

[0043] According to the present invention, the solvent is selected from decalin.

[0044] In the present invention, decalin is used as the solvent. Due to its high volatility, it is not only easy to remove from the system, but also enables the prepared UHMWPE fiber to have a low moisture content (not more than 3wt%) and can be recycled.

[0045] According to the present invention, the swelling conditions are: swelling temperature 85-100° C., swelling time 1.5-3.5 h.

[0046] According to the present invention, based on the total weight of the swelling liquid, the amount of the ultra-high molecular weight polyethylene is 5-9wt%, preferably 6-7wt%; the amount of the flame retardant is 0.03-0.3wt%, preferably 0.03%-0.1wt%; the amount of the antioxidant is 0.5-0.9wt%, preferably 0.6-0.8wt%.

[0047] In the present invention, the amount of the solvent is not particularly limited and can be a conventional amount in the art as long as each component meets the above range.

[0048] Furthermore, when the amounts of the ultra-high molecular weight polyethylene, the flame retardant and the antioxidant meet the above ranges, the prepared UHMWPE fiber has stronger flame retardancy and aging resistance.

[0049] According to the present invention, the flame retardant is a phosphate flame retardant, preferably selected from resorcinol bis(diphenyl phosphate) and / or bisphenol A bis(diphenyl phosphate).

[0050] According to the present invention, the antioxidant is selected from at least one of β-(4-hydroxy-3,5-di-tert-butylphenyl) propionate, tris(nonylphenol) phosphite, tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite, didodecyl thiodipropionate and tris(2,4-di-tert-butylphenyl) phosphite.

[0051] In the present invention, the flame retardant is selected from phosphate flame retardants, which decompose into a non-volatile glassy substance at the combustion temperature, wrap around the polymer surface, and form an isolation film to achieve a flame retardant effect. Therefore, the flame retardant effect is long-lasting. In addition, this type of flame retardant has good compatibility with the polymer substrate, and has the characteristics of water resistance, weather resistance, heat resistance and migration resistance. It is an environmentally friendly flame retardant, so that the fiber prepared therefrom has a wider range of applications.

[0052] In the present invention, when the flame retardant is resorcinol bis(diphenyl phosphate) and bisphenol A bis(diphenyl phosphate) present at the same time, the ratio of the two is 1:(1-3).

[0053] According to the present invention, the viscosity average molecular weight of the ultra-high molecular weight polyethylene is 5-6 million, preferably 5.5-6 million.

[0054] According to a preferred embodiment of the present invention:

[0055] Step 1, 5-9wt% of ultra-high molecular weight polyethylene and an additive selected from a flame retardant and an antioxidant are swollen in decalin at a temperature of 85-100° C. for 1.5-3.5 hours to obtain a swelling solution;

[0056] Step 2, the swelling liquid is sequentially mixed and melted in 6 stages with temperatures of 80-90° C., 110-130° C., 145-160° C., 160-170° C., 160-170° C., and 160-170° C. in a twin-screw extruder with a feed port temperature of 25-40° C., and then extruded to obtain a polymer melt at 150-165° C.;

[0057] Step 3: The polymer melt is subjected to a temperature of 80-140°C, a side blowing temperature of 90-120°C, and a side blowing air volume of 400-800N. 3 / h annular cooling jacket for solvent removal, and then the temperature is 75-140℃ and the air volume is 200-800N 3 The fiber is drawn in a spinning shaft with a speed of 1500 / h and drawn in four-stage drawing rollers with frequencies of 15-20, 20-25, 20-25 and 25-30 respectively to obtain ultra-high molecular weight polyethylene fibers.

[0058] The second aspect of the present invention provides an ultra-high molecular weight polyethylene fiber prepared by the above method.

[0059] The third aspect of the present invention provides an application of the above method and / or the above ultra-high molecular weight polyethylene fiber in the fields of labor protection products and protective products with flame retardant properties.

[0060] The present invention will be described in detail below by way of examples. In the following examples,

[0061] The breaking strength is measured by GB / T 19975-2005 method;

[0062] The modulus is measured by GB / T 19975-2005 method;

[0063] The elongation is measured by GB / T 29554-2013 method;

[0064] UL94 rating is obtained through the UL 94HB flammability standard method;

[0065] The limiting oxygen index (LOI) is measured by an oxygen index meter;

[0066] Moisture content is measured by vacuum drying oven instrument;

[0067] The dryness rate is measured by GB / T 14346-2015 method;

[0068] All raw materials are commercially available.

[0069] Example 1

[0070] Step 1, dissolving 6wt% of ultra-high molecular weight polyethylene, 0.1wt% of resorcinol bis(diphenyl phosphate) and 0.1wt% of bisphenol A bis(diphenyl phosphate), and 0.7wt% of tris(nonylphenol) phosphite in decahydronaphthalene, and swelling at a temperature of 95° C. for 3 hours to obtain a swelling solution;

[0071] Step 2, the swelling liquid is sequentially mixed and melted in 6 stages at temperatures of 85° C., 125° C., 150° C., 165° C., 165° C., and 165° C. in a twin-screw extruder with a feed port temperature of 25° C., and then extruded to obtain a polymer melt at 146° C.;

[0072] Step 3: The polymer melt is subjected to a temperature of 105°C, a side blowing temperature of 115°C, and a side blowing air volume of 610N. 3 / h ring cooling jacket to remove the solvent, and then send in a temperature of 80℃ and an air volume of 255N 3 The fiber was drawn in a spinning shaft with a speed of 1 / h and four-stage drawing rollers with frequencies of 19.8, 20.5, 20.5 and 26.5 respectively to obtain ultra-high molecular weight polyethylene fibers.

[0073] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0074] Example 2

[0075] The method is consistent with that of Example 1, except that the amount of resorcinol bis(diphenyl phosphate) used is 0.03 wt % and the amount of bisphenol A bis(diphenyl phosphate) used is 0.03 wt %.

[0076] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0077] Example 3

[0078] The method is consistent with that of Example 1, except that the feed port temperature of the twin-screw extruder is 35°C.

[0079] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0080] Example 4

[0081] The method is consistent with that in Example 1, except that the temperatures of the six stages of mixing and melting are 90°C, 130°C, 160°C, 170°C, 170°C, and 170°C, respectively.

[0082] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0083] Example 5

[0084] The method is consistent with that in Example 1, except that the extrusion port of the twin-screw extruder is 170° C. The obtained ultra-high molecular weight polyethylene fiber is tested, and the results of its breaking strength, modulus, UL94 grade and limiting oxygen index LOI are shown in Table 1.

[0085] Example 6

[0086] The method is consistent with that of Example 1, except that the spinning tunnel temperature is 100°C and the air volume is 380N. 3 / h.

[0087] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0088] Example 7

[0089] The method is consistent with that of Example 1, except that the spinning tunnel is stretched using four stretching rollers with frequencies of 20, 23.5, 23.5, and 28, respectively.

[0090] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0091] Example 8

[0092] The method is consistent with that in Example 1, except that the mixing and melting sections are 5 sections, and the temperatures are 85°C, 125°C, 150°C, 165°C, and 165°C, respectively.

[0093] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0094] Example 9

[0095] The method is consistent with that in Example 1, except that the spinning tunnel is stretched using five stretching rollers with frequencies of 19.8, 20.5, 20.5, 26.5, and 28.5, respectively.

[0096] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0097] Comparative Example 1

[0098] The method is consistent with that of Example 1, except that no flame retardant is added.

[0099] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0100] Comparative Example 2

[0101] The method is consistent with that of Example 1, except that no antioxidant is added.

[0102] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0103] Comparative Example 3

[0104] The method is consistent with that of Example 1, except that no swelling treatment is performed.

[0105] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0106] Comparative Example 4

[0107] The method is consistent with that in Example 1, except that the spinning tunnel temperature is 160°C and the air volume is 850N. 3 / h.

[0108] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0109] Comparative Example 5

[0110] The method is consistent with that in Example 1, except that the temperatures of the six stages of mixing and melting are 95°C, 135°C, 165°C, 185°C, 185°C, and 185°C, respectively.

[0111] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0112] Comparative Example 6

[0113] The method is consistent with that of Example 1, except that the spinning tunnel is stretched using four stretching rollers with frequencies of 22, 27, 27, and 32, respectively.

[0114] The obtained ultra-high molecular weight polyethylene fiber was tested, and the breaking strength, modulus, UL94 grade and limiting oxygen index LOI results are shown in Table 1.

[0115] Test Case

[0116] The ultra-high molecular weight polyethylene fibers prepared in the examples and comparative examples were subjected to aging tests in an artificial weathering tester. The breaking strength, modulus, and aging rate of the ultra-high molecular weight polyethylene fibers after aging were a and aging rate b The results are shown in Table 2. The aging rate calculation formula is: (performance parameter before aging-performance parameter after aging) / performance parameter before aging*100%.

[0117] Table 1

[0118]

[0119]

[0120] Table 2 Properties of ultra-high molecular weight polyethylene fibers after aging

[0121]

[0122] Note: Aging rate a:The change of breaking strength of UHMWPE fiber after aging compared with that before aging; Aging rate b :The change of modulus of UHMWPE fiber after aging compared with that before aging. The higher the aging rate, the worse the aging resistance.

[0123] It can be seen from Table 1 that the results of Examples 1-7 compared with Comparative Examples 1-2 without adding flame retardants and antioxidants can illustrate that the UL94 grade of the UHMWPE fiber obtained by the preparation method of the present invention is improved and the limiting oxygen index is significantly improved. It has excellent flame retardant and anti-aging properties as well as high mechanical properties.

[0124] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing ultra-high molecular weight polyethylene fiber, characterized in that: The preparation method comprises the following steps: Step 1, swelling the ultra-high molecular weight polyethylene, the flame retardant and the antioxidant in a solvent to obtain a swelling liquid; Step 2, kneading, melting and extruding the swelling liquid in a twin-screw extruder to obtain a polymer melt; Step 3, feeding the polymer melt into a spinning tunnel for drawing to obtain ultra-high molecular weight polyethylene fibers; The feed port temperature of the twin-screw extruder is 25-40°C, the temperature of the mixing and melting section is 80-180°C; the extrusion port temperature of the twin-screw extruder is 145-170°C; In the spinning tunnel, the spinning tunnel temperature is 75-140°C, and the air volume is 200-800N. 3 / h; The drafting ratio of the drafting is 15-30; The mixing and melting sections are 5-7 mixing and melting sections; The temperature of the first mixing and melting section is 80-90°C, the temperature of the second mixing and melting section is 110-130°C, the temperature of the third mixing and melting section is 145-160°C, the temperature of the fourth mixing and melting section is 160-170°C, the temperature of the fifth mixing and melting section is 160-170°C, the temperature of the sixth mixing and melting section is 160-170°C, and the temperature of the seventh mixing and melting section is 160-170°C; The drafting is 3-5 stages of drafting; Among them, the drafting ratio of the first drafting stage is 15-20, the drafting ratio of the second drafting stage is 20-25, the third drafting ratio is 20-25, the fourth drafting ratio is 25-30, and the fifth drafting ratio is 25-30.

2. The preparation method according to claim 1, wherein The preparation method further comprises: a step of removing the solvent from the polymer melt, and sending the polymer melt from which the solvent has been removed into a spinning tunnel for drawing; The conditions for removing the solvent are: temperature of 80-140°C, side blowing temperature of 90-120°C, side blowing air volume of 400-800N 3 / h.

3. The preparation method according to claim 1 or 2, wherein The solvent is selected from decahydronaphthalene.

4. The preparation method according to claim 1 or 2, wherein: The swelling conditions are: swelling temperature 85-100° C., swelling time 1.5-3.5 h.

5. The preparation method according to claim 1 or 2, wherein: Based on the total weight of the swelling liquid, the amount of the ultra-high molecular weight polyethylene is 5-9wt%; the amount of the flame retardant is 0.03-0.3wt%; and the amount of the antioxidant is 0.5-0.9wt%.

6. The preparation method according to claim 5, wherein: Based on the total weight of the swelling liquid, the amount of the ultra-high molecular weight polyethylene is 6-7wt%; the amount of the flame retardant is 0.03%-0.1wt%; and the amount of the antioxidant is 0.6-0.8wt%.

7. The preparation method according to claim 1 or 2, wherein: The flame retardant is a phosphate flame retardant; And / or, the antioxidant is selected from at least one of β-(4-hydroxy-3,5-di-tert-butylphenyl) propionate, tris(nonylphenol) phosphite, tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite, didodecyl thiodipropionate and tris(2,4-di-tert-butylphenyl) phosphite.

8. The preparation method according to claim 7, wherein: The phosphate flame retardant is selected from resorcinol bis(diphenyl phosphate) and / or bisphenol A bis(diphenyl phosphate).

9. The preparation method according to claim 1 or 2, wherein: The viscosity average molecular weight of the ultra-high molecular weight polyethylene is 5-6 million.

10. The preparation method according to claim 1 or 2, wherein: The viscosity average molecular weight of the ultra-high molecular weight polyethylene is 5.5-6 million.

11. Ultra-high molecular weight polyethylene fiber prepared by the method according to any one of claims 1 to 10.

12. A method for preparing the ultra-high molecular weight polyethylene fiber according to any one of claims 1 to 10 or use of the ultra-high molecular weight polyethylene fiber according to claim 11 in the field of labor protection products and / or protective products.

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