Low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament and preparation method thereof

Abstract

The present application discloses a low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament, comprising the following components in parts by weight: 65-75 parts of ultra-molecular weight polyethylene, 25-35 parts of high-density polyethylene, 2-5 parts of a novel phosphorus-nitrogen-containing nano-flame retardant, 1-4 parts of an antioxidant, and 1-2.5 parts of a lubricant. The low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament and its preparation method provided herein utilize a novel phosphorus-nitrogen-containing nano-flame retardant with improved flame retardancy in the monofilament, thereby achieving a low flame retardant content in the ultra-high molecular weight polyethylene monofilament while meeting the required high flame retardancy. This reduces the amount of flame retardant used and the effect of the flame retardant on the mechanical properties, such as strength, of the ultra-high molecular weight polyethylene monofilament. Consequently, the low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament exhibits high flame retardancy while also having good strength.

Description

Technical Field

[0001] The present invention generally relates to the technical field of monofilaments, and in particular to low-smoke flame-retardant ultra-high molecular weight polyethylene monofilaments and a preparation method thereof. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber is a new generation of high-performance fibers made from linear polyethylene with a molecular weight of over 1 million. Due to its lightweight, weak adhesion, low surface tension, strong impact resistance, excellent chemical resistance, good cut resistance, and self-lubrication, UHMWPE fiber is widely used in products such as marine ropes and protective nets, fishing line, cut-resistant gloves, and lightweight ballistic armor. Because UHMWPE fiber is flammable and produces high smoke and molten dripping during combustion, flame retardants are often added to existing UHMWPE fibers to improve their safety.

[0003] Since the flame retardant properties of existing flame retardants are average, in order to meet the high flame retardant properties of UHMWPE fibers, more flame retardants need to be added to the UHMWPE fibers, resulting in a decrease in the strength of the UHMWPE fibers. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament and a preparation method thereof.

[0005] In a first aspect, the present application provides a low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament, comprising the following components in parts by weight:

[0006] 65-75 parts of ultra-molecular weight polyethylene, 25-35 parts of high-density polyethylene, 2-5 parts of phosphorus-nitrogen-containing nano flame retardant, 1-4 parts of antioxidant, 1-2.5 parts of lubricant;

[0007] The phosphorus-nitrogen-containing nano flame retardant is prepared by the following preparation method:

[0008] S100: adding nano-silica particles, a silane modifier, and an acidic pH regulator to a 60-90% ethanol aqueous solution in sequence to prepare a first mixed solution, wherein the pH value of the first mixed solution is 3-4, then heating the first mixed solution to 60-70° C. and reacting for 4-6 hours, and then filtering, washing, and drying the first mixed solution to prepare nano-silica particles having double bond groups on the surface;

[0009] S200: Under a nitrogen atmosphere, acrylamide and a 37% formaldehyde solution are mixed in an aqueous solution and phosphorous acid is subsequently added to prepare a second mixed solution. The second mixed solution is then heated to 60-70° C. and reacted for 1-3 hours to prepare an acryloyl bisphosphonic acid flame retardant solution.

[0010] S300: mixing nano-silica particles containing double bond groups and an initiator in an acryloyl bisphosphonic acid flame retardant solution to prepare a third mixed solution, and then heating the third mixed solution to 60-70° C. and reacting for 7-9 hours to prepare nano-silica modified particles;

[0011] S400: Adding nano-silica modified particles and an alkaline pH regulator to the aqueous solution in sequence to obtain a fourth mixed solution, wherein the pH value of the fourth mixed solution is 4-6, then adding a metal salt to the fourth mixed solution and soaking it for 2-8 hours, and then filtering, washing and drying the fourth mixed solution to obtain a phosphorus-nitrogen-containing nano flame retardant.

[0012] Furthermore, the weight ratio of the nano-silica particles to the silane modifier is 1:(0.4-0.6).

[0013] Furthermore, the weight ratio of acrylamide, phosphorous acid, formaldehyde solution, nano-silica particles containing double bond groups and initiator is 100:(230-265):(230-260):(60-70):(6-13).

[0014] Furthermore, the weight ratio of the modified nano-silica particles to the metal salt is 1:(0.1-0.2).

[0015] Furthermore, the silane modifier is selected from one or more of vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and 3-methacryloxypropyltrimethoxysilane.

[0016] Furthermore, the initiator is selected from one or more of sodium persulfate, potassium persulfate, and azobisisobutylcyanide.

[0017] Furthermore, the metal salt is selected from Cu 2+ 、Zn 2+ , Ca 2+ Mg 2+ 、Fe 3+ 、A l 3+ One or more of nitrates, acetates, and chlorides.

[0018] Furthermore, the antioxidant is selected from one or more of antioxidant 1010 , antioxidant 168 , and antioxidant 1024 .

[0019] Furthermore, the lubricant is selected from one or more of polyethylene wax and calcium stearate.

[0020] In a second aspect, the present application also provides a method for preparing a low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament, comprising the following steps:

[0021] Mixing ultra-molecular weight polyethylene, high-density polyethylene, phosphorus-nitrogen-containing nano flame retardant, antioxidant, and lubricant to prepare a raw material mixture;

[0022] The raw material mixture is sequentially granulated and spun to produce low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament.

[0023] The low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament and its preparation method provided by the present application use a new phosphorus-nitrogen-containing nano-flame retardant with better flame retardant properties in the monofilament, so that the ultra-high molecular weight polyethylene monofilament has a low flame retardant content while meeting the required high flame retardant properties, that is, the amount of flame retardant used is reduced, and the influence of the flame retardant on the mechanical properties such as the strength of the ultra-high molecular weight polyethylene monofilament is reduced, thereby achieving the low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament having high flame retardant properties while also having good strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0025] Figure 1 The preparation route of the phosphorus-nitrogen-containing nano flame retardant provided in this embodiment;

[0026] Figure 2 This is a flow chart for preparing the low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament provided in this embodiment. DETAILED DESCRIPTION

[0027] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0028] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0029] Please refer to the attached Figure 1 The embodiment of the present application provides a low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament, comprising the following components in parts by weight: 65-75 parts of ultra-molecular weight polyethylene, 25-35 parts of high-density polyethylene, 2-5 parts of phosphorus-nitrogen-containing nano flame retardant, 1-4 parts of antioxidant, and 1-2.5 parts of lubricant.

[0030] The phosphorus-nitrogen-containing nano flame retardant in the above components is prepared by the following preparation method:

[0031] S100: adding nano-silica particles, a silane modifier, and an acidic pH regulator to a 60-90% ethanol aqueous solution in sequence to prepare a first mixed solution, wherein the pH value of the first mixed solution is 3-4, then heating the first mixed solution to 60-70° C. and reacting for 4-6 hours, and then filtering, washing, and drying the first mixed solution to prepare nano-silica particles having double bond groups on the surface;

[0032] S200: Under a nitrogen atmosphere, acrylamide and a 37% formaldehyde solution are mixed in an aqueous solution and phosphorous acid is subsequently added to prepare a second mixed solution. The second mixed solution is then heated to 60-70° C. and reacted for 1-3 hours to prepare an acryloyl bisphosphonic acid flame retardant solution.

[0033] S300: mixing nano-silica particles containing double bond groups and an initiator in an acryloyl bisphosphonic acid flame retardant solution to prepare a third mixed solution, and then heating the third mixed solution to 60-70° C. and reacting for 7-9 hours to prepare nano-silica modified particles;

[0034] S400: Adding nano-silica modified particles and an alkaline pH regulator to the aqueous solution in sequence to obtain a fourth mixed solution, wherein the pH value of the fourth mixed solution is 4-6, then adding a metal salt to the fourth mixed solution and soaking it for 2-8 hours, and then filtering, washing and drying the fourth mixed solution to obtain a phosphorus-nitrogen-containing nano flame retardant.

[0035] This embodiment provides a novel phosphorus-nitrogen-containing nano flame retardant, which improves the flame retardant properties of ultra-high molecular weight polyethylene monofilaments through the following aspects, specifically:

[0036] First, when the ultra-high molecular weight polyethylene monofilament is subjected to high temperature, the phosphorus-nitrogen-containing nano flame retardant will thermally decompose at high temperature to produce nitrogen-containing non-combustible gases such as ammonia; second, the phosphorus-nitrogen-containing nano flame retardant will also thermally decompose at high temperature to produce phosphoric acid, metaphosphoric acid and other phosphorus-containing flame retardants, which can dehydrate and carbonize the surface of the ultra-high molecular weight polyethylene monofilament to form a carbonized surface layer on the surface of the ultra-high molecular weight polyethylene monofilament. At the same time, at high temperature, polymer cross-linking will be initiated between the silicon dioxide in the monofilament and the carbonized surface layer, so that a flame-retardant carbon layer with C-Si bonds is formed between the carbonized surface layer and the silicon dioxide; third, the complexed metal ions in the phosphorus-nitrogen-containing nano flame retardant will thermally decompose to form metal oxides when heated, and the metal oxides are deposited on the surface of the ultra-high molecular weight polyethylene monofilament and part of the metal oxides are combined with the flame-retardant carbon layer. The nitrogen-containing non-combustible gas generated above can dilute the oxygen concentration in the environment surrounding the monofilament. The flame-retardant carbon layer and the metal oxide can both block external oxygen and heat from entering the ultra-high molecular weight polyethylene monofilament and reduce the amount of combustible gas released by decomposition within the ultra-high molecular weight polyethylene monofilament. Through the synergistic effect of the nitrogen-containing non-combustible gas and the flame-retardant carbon layer and metal oxide attached to the surface of the monofilament, the limiting oxygen index, smoke suppression performance and anti-dripping performance of the ultra-high molecular weight polyethylene monofilament can be significantly improved, thereby improving the flame retardant performance of the ultra-high molecular weight polyethylene monofilament. At the same time, the flame-retardant carbon layer has good adhesion stability under the dual fixation of CSi bonds and metal oxides, thereby improving the flame retardant durability of the ultra-high molecular weight polyethylene monofilament.

[0037] In addition, the new phosphorus-nitrogen-containing nano flame retardant provided in this embodiment is not only halogen-free and has a high safety factor, but is also in the form of nanoparticles, so that the phosphorus-nitrogen-containing nano flame retardant can be evenly distributed in the polyethylene resin, thereby improving the distribution uniformity of the phosphorus-nitrogen-containing nano flame retardant in the ultra-high molecular weight polyethylene monofilament.

[0038] Compared with existing flame retardants, the phosphorus-nitrogen-containing nano flame retardant provided in this embodiment has higher flame retardant properties. As a result, while the ultra-high molecular weight polyethylene monofilament meets the required high flame retardant properties, the flame retardant content in the polyethylene monofilament is low, that is, the amount of flame retardant used is reduced, and the impact of the flame retardant on the mechanical properties such as the strength of the ultra-high molecular weight polyethylene monofilament is reduced. As a result, the low-smoke flame retardant ultra-high molecular weight polyethylene monofilament has high flame retardant properties while also having good strength.

[0039] Optionally, in step S100, sequentially adding nano-silica particles, a silane modifier, and an acidic pH regulator to a 60-90% ethanol aqueous solution specifically includes: first adding the nano-silica particles to a 60-90% ethanol aqueous solution, then ultrasonically dispersing the ethanol aqueous solution containing the nano-silica particles for 5-10 minutes to uniformly disperse the nano-silica particles in the ethanol aqueous solution, then adding the silane modifier, and then adding the acidic pH regulator after adding the silane modifier to adjust the pH of the first mixed solution to 3-4 to promote the hydrolysis of the silane. After the reaction is completed, the first mixed solution is filtered to obtain a solid substance, and the solid substance is washed with water and dried to obtain nano-silica particles containing double bond groups. The average particle size of the nano-silica particles can be, but is not limited to, 20-30 nm. The viscosity-average molecular weight of the ultra-molecular-weight polyethylene resin can be, but is not limited to, between 1,000,000 and 2,000,000. The viscosity-average molecular weight of the high-density polyethylene resin can be 100,000-300,000 and have a melt index of 5-10 g / 10 min. Optionally, the weight ratio of the nano-silica particles to the silane modifier is 1:(0.4-0.6), i.e., the weight of the silane modifier is 40%-60% of the weight of the nano-silica particles. Optionally, the silane modifier is selected from one or more of vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and 3-methacryloyloxypropyltrimethoxysilane. The acidic pH adjuster is selected from one or more of concentrated hydrochloric acid, concentrated sulfuric acid, and glacial acetic acid.

[0040] Optionally, in steps S200 and S300, after acrylamide and formaldehyde solution are mixed in an aqueous solution, they can be stirred for a period of time before adding phosphorous acid to make the reaction more complete. Nano-silica particles containing double bond groups can be added to the acrylyl bisphosphonic acid flame retardant solution before the initiator, and after the third mixed solution reacts, it is filtered and the filtered solid matter is washed and dried to prepare nano-silica modified particles. Optionally, the weight ratio of acrylamide, phosphorous acid, formaldehyde solution, nano-silica particles containing double bond groups and initiator is 100: (230-265): (230-260): (60-70): (6-13). Optionally, the initiator is selected from one or more of sodium persulfate, potassium persulfate and azobisisobutyl cyanide.

[0041] Optionally, in step S400, the weight ratio of the modified nano-silica particles to the metal salt is 1:(0.1-0.2), that is, the weight of the metal salt is 10%-20% of the weight of the modified nano-silica particles. 2 + 、Zn 2+ , Ca2+ Mg 2+ 、Fe 3+ 、A l 3+ One or more of nitrate, acetate, and chloride. The alkaline pH regulator is selected from sodium hydroxide, sodium bicarbonate, etc.

[0042] Optionally, the antioxidant may be, but is not limited to, one or more of antioxidant 1010, antioxidant 168, and antioxidant 1024, which can effectively prevent thermal degradation of the polyethylene resin and improve the aging resistance of the polyethylene resin.

[0043] Optionally, the lubricant may be, but is not limited to, one or more of polyethylene wax and calcium stearate, to effectively improve the fluidity of the polyethylene resin.

[0044] Please refer to the attached Figure 2 The present invention also provides a method for preparing a low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament, comprising the following steps:

[0045] Mixing ultra-molecular weight polyethylene, high-density polyethylene, phosphorus-nitrogen-containing nano flame retardant, antioxidant, and lubricant to prepare a raw material mixture;

[0046] The raw material mixture is sequentially granulated and spun to produce low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament.

[0047] Optionally, the above-mentioned mixing process can be carried out at room temperature using a high-speed mixer, wherein the high-speed mixer speed is 800-1000r / min and the mixing time is 10-15min. The raw material mixture is extruded and granulated through a twin-screw extruder, and then melt-spun by a single screw and the spinning is water-cooled, high-multiple hot stretched and wound to prepare low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament. Among them, the extrusion temperature of the twin-screw extruder can be but not limited to 280-290°C, the single-screw spinning temperature can be but not limited to 290-310°C, the high-multiple hot stretching temperature can be but not limited to 70-100°C, and the stretching ratio can be but not limited to 9-12.

[0048] This embodiment adopts melt spinning, which has the advantages of low cost, simple process, no need to use organic solvents, etc. compared with gel spinning, low cost and little impact on the environment.

[0049] In addition, the present application also provides the following examples to illustrate the flame retardant properties and mechanical properties of the ultra-high molecular weight polyethylene monofilament provided in the present application, as follows:

[0050] Example 1:

[0051] Preparation of phosphorus-nitrogen-containing nano flame retardants:

[0052] 10 g of nano-silica particles were added to an 80% ethanol aqueous solution and ultrasonically dispersed for 10 minutes, followed by adding 4 g of allyltriethoxysilane, and then adding glacial acetic acid to adjust the solution to prepare a first mixed solution, wherein the pH value of the first mixed solution was 3.5, and then the first mixed solution was heated to 70° C. and reacted for 4 hours. After the reaction, the first mixed solution was filtered, washed with water, and dried to prepare nano-silica particles having double bond groups on the surface;

[0053] In a nitrogen atmosphere, 21.03 g of acrylamide and 48.69 g of formaldehyde solution were mixed and dissolved in 20 g of water, stirred for a period of time, and 49.2 g of phosphorous acid was added to prepare a second mixed solution. The second mixed solution was then heated to 70°C and reacted for 2 hours to prepare a colorless and transparent acryloyl bisphosphonic acid flame retardant solution.

[0054] 13 g of nano-silica particles containing double bond groups were added to the acryloyl diphosphoric acid flame retardant solution prepared above, and then 1.6 g of potassium persulfate was added to prepare a third mixed solution. The third mixed solution was then heated to 60° C. and reacted for 4 hours. After the reaction was completed, the third mixed solution was filtered and dried to prepare nano-silica modified particles.

[0055] 20 g of nano-silica modified particles were soaked in a NaOH aqueous solution to prepare a fourth mixed solution, and the pH value of the fourth mixed solution reached 4.5. Subsequently, 2 g of anhydrous calcium chloride was added to the fourth mixed solution and immersed for 4 hours. The fourth mixed solution was then filtered, washed with water and dried to obtain a phosphorus-nitrogen nano flame retardant.

[0056] Preparation of ultra-high molecular weight polyethylene monofilament:

[0057] 700g of ultra-high molecular weight polyethylene resin, 300g of high-density polyethylene resin, 40g of a phosphorus-nitrogen nano-flame retardant, 10g of antioxidant 1010, and 15g of calcium stearate were mixed in a high-speed mixer at room temperature for 10 minutes. The mixture was then extruded and pelletized in a twin-screw extruder at 280°C. The mixture then underwent single-screw melt spinning, water cooling, high-ratio hot stretching, and winding to produce low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament. The spinning temperature was 300°C, the hot stretching temperature was 80°C, the initial stretching ratio was 5, and the high-ratio stretching ratio was 11.

[0058] Example 2:

[0059] Preparation of phosphorus-nitrogen-containing nano flame retardants:

[0060] 25 g of nano-silica particles were added to a 70% ethanol aqueous solution and ultrasonically dispersed for 10 minutes, followed by the addition of 12.5 g of 3-methacryloxypropyltrimethoxysilane, and then the solution was adjusted by adding glacial acetic acid to prepare a first mixed solution, wherein the pH value of the first mixed solution was 4. The first mixed solution was then heated to 65° C. and reacted for 4 hours. After the reaction was completed, the first mixed solution was filtered, washed with water, and dried to prepare nano-silica particles having double bond groups on the surface.

[0061] In a nitrogen atmosphere, 54.3 g of acrylamide and 125.4 g of formaldehyde solution were mixed and dissolved in water, stirred for a period of time, and 127.2 g of phosphorous acid was added to prepare a second mixed solution. The second mixed solution was then heated to 70° C. and reacted for 2 h to prepare a colorless, transparent acryloyl bisphosphonic acid flame retardant solution.

[0062] 32.6 g of nano-silica particles containing double bond groups were added to the prepared acryloyl diphosphoric acid flame retardant solution, and then 4 g of potassium persulfate was added to prepare a third mixed solution. The third mixed solution was then heated to 60° C. and reacted for 4 hours. After the reaction was completed, the third mixed solution was filtered and dried to prepare nano-silica modified particles.

[0063] 50 g of nano-silica modified particles were immersed in a NaOH aqueous solution to prepare a fourth mixed solution, and the pH value of the fourth mixed solution reached 4.5. Subsequently, 6 g of anhydrous calcium chloride was added to the fourth mixed solution and immersed for 6 hours. The fourth mixed solution was then filtered, washed with water and dried to obtain a phosphorus-nitrogen nano flame retardant.

[0064] Preparation of ultra-high molecular weight polyethylene monofilament:

[0065] 1500g of ultra-high molecular weight polyethylene resin, 642g of high-density polyethylene resin, 80g of a phosphorus-nitrogen nano-flame retardant, 28.75g of antioxidant 1010, and 42.86g of calcium stearate were mixed in a high-speed mixer at room temperature for 10 minutes. The mixture was then extruded and pelletized in a twin-screw extruder at 290°C. The mixture then underwent single-screw melt spinning, water cooling, high-ratio hot stretching, and winding to produce low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament. The spinning temperature was 310°C, the hot stretching temperature was 80°C, the initial stretch ratio was 5.8, and the high-ratio stretch ratio was 10.

[0066] Example 3-11:

[0067] Example 3: In the preparation of ultra-high molecular weight polyethylene monofilament, the weight of the phosphorus-nitrogen-containing nano flame retardant is 30 g, and the rest is the same as Example 1.

[0068] Example 4: In the preparation of the phosphorus-nitrogen-containing nano flame retardant, the metal salt is magnesium chloride hexahydrate and weighs 2 g, and the rest is the same as in Example 1.

[0069] Example 5: In the preparation of the phosphorus-nitrogen-containing nano flame retardant, the metal salt is anhydrous aluminum chloride and weighs 2 g, and the rest is the same as in Example 1.

[0070] Example 6: In the preparation of the phosphorus-nitrogen-containing nano flame retardant, the metal salt is copper chloride dihydrate and weighs 2 g, and the rest is the same as in Example 1.

[0071] Example 7: In the preparation of the phosphorus-nitrogen-containing nano flame retardant, the metal salt is ferric chloride hexahydrate and weighs 5 g, and the rest is the same as in Example 2.

[0072] Example 8: In the preparation of the phosphorus-nitrogen-containing nano flame retardant, the metal salt is ferric chloride hexahydrate and weighs 7 g, and the rest is the same as in Example 2.

[0073] Example 9: In the preparation of the phosphorus-nitrogen-containing nano flame retardant, the metal salt is ferric chloride hexahydrate and weighs 8 g, and the rest is the same as in Example 2.

[0074] Example 10: In the preparation of the phosphorus-nitrogen-containing nano flame retardant, the metal salt is ferric chloride hexahydrate and weighs 9 g, and the rest is the same as in Example 2.

[0075] Comparative Example 1:

[0076] Preparation of phosphorus-nitrogen-containing nano flame retardants:

[0077] 10 g of nano-silica particles were added to an 80% ethanol aqueous solution and ultrasonically dispersed for 10 minutes, followed by adding 4 g of allyltriethoxysilane, and then adding glacial acetic acid to adjust the solution to prepare a first mixed solution, wherein the pH value of the first mixed solution was 3.5, and then the first mixed solution was heated to 70° C. and reacted for 4 hours. After the reaction, the first mixed solution was filtered, washed with water, and dried to prepare nano-silica particles having double bond groups on the surface;

[0078] In a nitrogen atmosphere, 21.03 g of acrylamide and 48.69 g of formaldehyde solution were mixed and dissolved in water, stirred for a period of time, and 49.2 g of phosphorous acid was added to prepare a second mixed solution. The second mixed solution was then heated to 70°C and reacted for 2 hours to prepare a colorless and transparent acryloyl bisphosphonic acid flame retardant solution.

[0079] 13 g of nano-silica particles containing double bond groups were added to the acryloyl diphosphoric acid flame retardant solution prepared above, and then 1.6 g of potassium persulfate was added to prepare a third mixed solution. The third mixed solution was then heated to 60° C. and reacted for 4 hours. After the reaction was completed, the third mixed solution was filtered and dried to prepare a phosphorus-nitrogen-containing nano flame retardant.

[0080] Preparation of ultra-high molecular weight polyethylene monofilament:

[0081] 700g of ultra-high molecular weight polyethylene resin, 300g of high-density polyethylene resin, 40g of a phosphorus-nitrogen nano-flame retardant, 10g of antioxidant 1010, and 15g of calcium stearate were mixed in a high-speed mixer at room temperature for 10 minutes. The mixture was then extruded and pelletized in a twin-screw extruder at 280°C. The mixture then underwent single-screw melt spinning, water cooling, high-ratio hot stretching, and winding to produce low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament. The spinning temperature was 300°C, the hot stretching temperature was 80°C, the initial stretching ratio was 5.7, and the high-ratio stretching ratio was 11.6.

[0082] Comparative Example 2:

[0083] 700 g of ultra-high molecular weight polyethylene resin, 300 g of high-density polyethylene resin, 40 g of phosphorus-nitrogen flame retardant (the flame retardant is HF-831 flame retardant produced by Anhui Stable Jiaxin Material Technology Co., Ltd.), 8 g of antioxidant 1010, and 14 g of calcium stearate were mixed in a high-speed mixer at room temperature for 10 minutes, then put into a twin-screw extruder, extruded and granulated at 280°C, and then single-screw melt spinning was adopted, the spinning temperature was 290°C, water cooling, the initial stretching ratio was 5.5, the hot stretching temperature was 80°C, the stretching ratio was 10.3, and the ultra-high molecular weight polyethylene monofilament was obtained after winding.

[0084] Test method:

[0085] (1) Flame retardant performance test: The limiting oxygen index (LOI) of the fiber was tested according to GB / T5454 1997 “Determination of combustion behavior of textiles - Determination of oxygen index”; 0.5±0.01g of UHMWPE fiber was placed on a wire mesh and heated with an outer flame. The flame height was controlled at about 4cm, and the droplets and smoke generated during the combustion of the fiber were recorded.

[0086] (2) Mechanical property test: The breaking strength of the fiber was tested according to GB / T4344-2008 “Test method for tensile properties of chemical fiber filaments”, with a tensile distance of 200 mm and a tensile speed of 200 m / min.

[0087] The performance of the ultra-high molecular weight polyethylene monofilaments prepared in the above embodiments was tested, and the test results are shown in the following table:

[0088]

[0089] Based on the above table, we can see that:

[0090] 1. Compared with Comparative Example 2, the low-smoke flame-retardant ultra-high molecular weight polyethylene monofilaments in Examples 1-10 and Comparative Example 1 have significant improvements in limiting oxygen index, smoke emission, and anti-dripping effect. At the same time, the strength of the ultra-high molecular weight polyethylene monofilament is less affected and not obvious, which proves that the ultra-high molecular weight polyethylene monofilament provided in this application has higher flame retardant properties while taking into account the strength of the monofilament.

[0091] 2. Compared with Comparative Example 1, the low-smoke flame-retardant ultra-high molecular weight polyethylene monofilaments of Examples 1-10 have better limiting oxygen index, smoke emission and anti-melting dripping effects, which further proves that the phosphorus-nitrogen nano-flame retardant encapsulated with metal ions has better flame retardant properties, smoke suppression and anti-melting dripping effects than the phosphorus-nitrogen nano-flame retardant without encapsulated metal ions.

[0092] It should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used above to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention; the directional terms "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of such features.

[0093] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways, rotated 90 degrees or in other orientations, and the spatially relative descriptions used herein are interpreted accordingly.

[0094] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention herein is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features having similar functions disclosed in this application.

Claims

1. A low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament, characterized in that: The composition comprises the following components in parts by weight: 65-75 parts of ultra-molecular weight polyethylene, 25-35 parts of high-density polyethylene, 2-5 parts of phosphorus-nitrogen nano flame retardant, 1-4 parts of antioxidant, 1-2.5 parts of lubricant; Wherein, the phosphorus-nitrogen-containing nano flame retardant is prepared by the following preparation method: S100: adding nano-silica particles, a silane modifier, and an acidic pH regulator to a 60-90% ethanol aqueous solution in sequence to prepare a first mixed solution, wherein the pH value of the first mixed solution is 3-4, then heating the first mixed solution to 60-70° C. and reacting for 4-6 hours, and then filtering, washing, and drying the first mixed solution to prepare nano-silica particles having double bond groups on the surface; S200: Under a nitrogen atmosphere, acrylamide and a 37% formaldehyde solution are mixed in an aqueous solution and phosphorous acid is subsequently added to prepare a second mixed solution. The second mixed solution is then heated to 60-70° C. and reacted for 1-3 hours to prepare an acryloyl bisphosphonic acid flame retardant solution. S300: mixing the nano-silica particles containing double bond groups and an initiator in the acryloyl bisphosphonic acid flame retardant solution to prepare a third mixed solution, and then heating the third mixed solution to 60-70° C. and reacting for 7-9 hours to prepare nano-silica modified particles; S400: adding the nano-silica modified particles and the alkaline pH regulator to the aqueous solution in sequence to obtain a fourth mixed solution, wherein the pH value of the fourth mixed solution is 4-6, then adding a metal salt to the fourth mixed solution and soaking it for 2-8 hours, and then filtering, washing and drying the fourth mixed solution to obtain the phosphorus-nitrogen-containing nano flame retardant.

2. The low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament according to claim 1, characterized in that: The weight ratio of the nano-silica particles to the silane modifier is 1:(0.4-0.6).

3. The low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament according to claim 1, characterized in that: The weight ratio of the acrylamide, the phosphorous acid, the formaldehyde solution, the nano-silica particles containing double bond groups and the initiator is 100:(230-265):(230-260):(60-70):(6-13).

4. The low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament according to claim 1, characterized in that The weight ratio of the modified nano-silica particles to the metal salt is 1:(0.1-0.2).

5. The low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament according to claim 1, characterized in that: The silane modifier is selected from one or more of vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and 3-methacryloxypropyltrimethoxysilane.

6. The low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament according to claim 1, characterized in that: The initiator is selected from one or more of sodium persulfate, potassium persulfate, and azobisisobutylcyanide.

7. The low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament according to claim 1, characterized in that: The metal salt is selected from Cu 2+ 、Zn 2+ , Ca 2+ Mg 2+ 、Fe 3+ 、Al 3+ One or more of nitrates, acetates, and chlorides.

8. The low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament according to claim 1, characterized in that: The antioxidant is selected from one or more of antioxidant 1010, antioxidant 168, and antioxidant 1024.

9. The low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament according to claim 1, characterized in that: The lubricant is selected from one or more of polyethylene wax and calcium stearate.

10. A method for preparing the low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament according to any one of claims 1 to 9, characterized in that: The following steps are involved: Mixing the super molecular weight polyethylene, the high density polyethylene, the phosphorus and nitrogen containing nano flame retardant, the antioxidant, and the lubricant to prepare a raw material mixture; The raw material mixture is sequentially subjected to granulation and spinning processes to obtain the low-smoke flame-retardant ultra-high molecular weight polyethylene monofilament.

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