Ultrahigh molecular weight polyethylene fiber as well as preparation method and application thereof

Abstract

The invention relates to a polyethylene fiber, and discloses an ultra-high molecular weight polyethylene fiber as well as a preparation method and application thereof. The fineness of the fiber is less than or equal to 30D, the tensile breaking strength is greater than or equal to 350N / tex, and the creep elongation is less than or equal to 3%. The preparation method comprises the following steps: (1) mixing an ultra-high molecular weight polyethylene raw material, a solvent I and an auxiliary agent I to obtain a mixed solution; (2) mixing the mixed solution, an auxiliary agent II, a nucleating agent and a solvent II, spinning, and pre-drafting to obtain a primary gel-spun yarn; the auxiliary agent II contains a coupling agent and an initiator; and (3) removing the solvent from the primary gel silk, and carrying out hot drawing treatment. The ultra-high molecular weight polyethylene fiber not only has smaller fineness, but also has larger strength and smaller creep elongation, and can have the advantages of small diameter, high strength and good creep resistance.

Description

Technical Field

[0001] The invention relates to polyethylene fiber, in particular to an ultra-high molecular weight polyethylene fiber and a preparation method and application thereof. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber is one of the three major high-performance fibers in the world, and has many excellent properties. UHMWPE fiber has the characteristics of high specific strength, high specific modulus, excellent impact resistance and good wear resistance. It can also withstand the corrosion of strong acids, strong alkalis and other chemicals, has a high electromagnetic wave transmittance, and has a lower friction coefficient than many materials. It is non-absorbent and has good biocompatibility. Therefore, UHMWPE fiber is widely used in many fields such as military protective materials, aerospace related materials, medical materials, radar antenna covers, and ship anchor ropes.

[0003] Fine-denier ultra-high molecular weight polyethylene fibers can be woven into high-end textiles that are soft to the touch and comfortable to wear. They can be used in soft protective equipment, wearable clothing, home textiles and other fields, and have high economic value. At present, the preparation method of fine-denier ultra-high molecular weight polyethylene fibers often adopts conventional wet spinning. The production cost, efficiency and other factors determine that there is a high solvent residue in the fiber product. The single fiber fineness is mostly above 2.5dtex, the texture is rough, and the feel is relatively rough, which limits its application and development in soft personal protection and other clothing fields; the fibers prepared by dry gel spinning using volatile solvents such as decalin and xylene have the advantages of low solvent residue, low extrusion temperature and large nozzle stretch ratio. Although it is easier to prepare ultra-fine denier and high-strength polyethylene fibers, there are problems such as poor spinning process stability and poor creep resistance. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of rough texture and poor creep resistance of fine-denier ultra-high molecular weight polyethylene fibers in the prior art, and to provide an ultra-high molecular weight polyethylene fiber and a preparation method and application thereof. The ultra-high molecular weight polyethylene fiber not only has a smaller fineness, but also has a larger tensile breaking strength and a smaller creep elongation, and can have the advantages of a thin diameter, high tensile breaking strength and good creep resistance.

[0005] In order to achieve the above objectives, the first aspect of the present invention provides an ultra-high molecular weight polyethylene fiber, wherein the fiber fineness is less than or equal to 30D, the fiber tensile strength at break is greater than or equal to 350N / tex, and the fiber creep elongation at 50°C is less than or equal to 3%.

[0006] A second aspect of the present invention provides a method for preparing an ultra-high molecular weight polyethylene fiber, comprising the following steps:

[0007] (1) mixing an ultra-high molecular weight polyethylene raw material, a solvent I and an additive I to obtain a mixed solution;

[0008] (2) mixing the mixed solution, auxiliary agent II, nucleating agent and solvent II, spinning and pre-stretching to obtain primary jelly filaments;

[0009] The auxiliary agent II contains a coupling agent and an initiator;

[0010] (3) After removing the solvent from the primary jelly silk, the silk is subjected to a heat drawing treatment.

[0011] The third aspect of the present invention provides an application of the ultra-high molecular weight polyethylene fiber provided in the first aspect or the ultra-high molecular weight polyethylene fiber prepared by the preparation method provided in the second aspect in bulletproof fabrics.

[0012] Through the above technical solution, the present invention has the following beneficial effects:

[0013] (1) The ultra-high molecular weight polyethylene fiber provided by the present invention has a fineness less than or equal to 30D, a tensile strength greater than or equal to 350N / tex, and a creep elongation of the fiber at 50°C less than or equal to 3%, and can have the advantages of thin diameter, high tensile strength and good creep resistance.

[0014] (2) The method provided by the present invention, by adding a coupling agent, an initiator and a nucleating agent during the spinning process, can facilitate subsequent drawing through the interaction between the coupling agent, the initiator, the nucleating agent and the spinning solution, so that the prepared fiber has a smaller fineness; at the same time, it can also effectively improve the tensile strength of the fiber and reduce the creep elongation of the fiber, thereby improving the creep resistance of the fiber, so that the fiber can have the advantages of thin diameter, high tensile strength and creep resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The crystal morphology diagram of the ultra-high molecular weight polyethylene fiber prepared in Example 1 of the present invention and Comparative Example 1;

[0016] Figure 2 Surface electron micrographs of ultra-high molecular weight polyethylene fibers obtained in Example 1 (B) of the present invention and Comparative Example 2 (A);

[0017] Figure 3 The creep elongation of the ultra-high molecular weight polyethylene fibers prepared in Example 1 (B) and Comparative Example 2 (A) of the present invention is measured by the hanging weight method at 50°C. DETAILED DESCRIPTION

[0018] 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.

[0019] As mentioned above, the first aspect of the present invention provides an ultra-high molecular weight polyethylene fiber, the fiber fineness of which is less than or equal to 30D, the tensile strength at break of which is greater than or equal to 350N / tex, and the creep elongation of which is less than or equal to 3% at 50°C.

[0020] According to the present invention, ultra-high molecular weight polyethylene refers to polyethylene with a molecular weight of more than 1 million. Preferably, the molecular weight of the ultra-high molecular weight polyethylene is 1 million to 8 million. More preferably, the density of the ultra-high molecular weight polyethylene is 0.97 to 0.98 g / cm 3 .

[0021] The fiber density is tested by GB / T14335, the fiber length is tested by GB / T14336, and the fiber fineness is calculated by the detected density and length. The tensile breaking strength is obtained by the GB / T14344-2008 test. Generally, the higher the temperature, the worse the creep resistance of the fiber, that is, under high temperature conditions, the creep resistance of the fiber is poor. According to the present invention, the creep elongation is measured by the hanging weight method, and parallel fibers of 1.5 m in length are placed in an environmental chamber for creep performance testing. The hanging weight is 20% of the single-filament breaking strength, the hanging time is 48 hours, and the test temperature is 50°C, that is, the creep elongation of the fiber is less than or equal to 3% when the hanging weight is 20% of the single-filament breaking strength and the temperature is 50°C.

[0022] The ultra-high molecular weight polyethylene fiber provided by the present invention can ensure the tensile strength and anti-creep performance of the fiber while ensuring a thin diameter, can ensure comfort during use, and is not prone to breakage and deformation.

[0023] According to the present invention, preferably, the tensile breaking strength of the fiber is 350-500N / tex, specifically 350N / tex, 400N / tex, 450N / tex, 500N / tex, or any value between these values; the fiber fineness is less than or equal to 10D. Under the above conditions, the fiber has a smaller diameter and is more comfortable during use. Further preferably, the tensile breaking strength of the fiber is greater than 370-400N / tex, and the creep elongation of the fiber at 50°C is less than or equal to 2.1%. The fiber under the above conditions has a higher tensile breaking strength and better creep resistance, is not easy to break during use, and is not easy to deform. Further preferably, the tensile breaking strength of the fiber is 370-380N / tex.

[0024] Preferably, the fiber contains a nucleating agent. The addition of the nucleating agent can significantly improve the tensile strength and creep resistance of the fiber, and can also significantly reduce the diameter of the obtained fiber.

[0025] Preferably, the nucleating agent is a β-crystal nucleating agent, and the β-crystal nucleating agent is an inorganic β-crystal nucleating agent and / or an organic β-crystal nucleating agent; the β-crystal nucleating agent can further induce the interface instability between the nucleating agent and the polyethylene phase, generate more crystallization nuclei, increase the number of nucleations, and thus reduce the grain size, increase the fiber thermal drawing ratio without breaking, and can significantly improve the tensile strength and creep resistance of the fiber, and can also significantly reduce the diameter of the obtained fiber. Considering that the tensile strength and creep resistance of the fiber can be further improved and the diameter of the fiber can be reduced, it is further preferred that the β-crystal nucleating agent is an inorganic β-crystal nucleating agent and an organic β-crystal nucleating agent, and the inorganic β-crystal nucleating agent is selected from at least one of calcium carbonate, calcium sulfate and yttrium oxide, and the organic β-crystal nucleating agent is selected from at least one of phenanthrene, anthracene, 2-mercaptobenzimidazole, triphenol dithiazine, dicarboxylate, aromatic diamide and TMB-5. More preferably, the content of the nucleating agent in the fiber is 1-11% by mass, and further preferably 5-11% by mass.

[0026] According to the present invention, the nucleating agent can be obtained by using XRD and corresponding to the standard spectrum detection of different nucleating agents. After determining each crystal, the content of each nucleating agent is measured in a suitable manner according to the type of each nucleating agent. For example, the test method of an inorganic β-crystalline nucleating agent or a nucleating agent with a melting point greater than or equal to 150°C can be: dissolving a fixed mass of ultra-high molecular weight polyethylene fiber by decalin at 120°C, filtering to obtain a solid phase, and weighing the fixed phase after drying. The content of the nucleating agent in the fiber is calculated by the mass of the solid phase and the added ultra-high molecular weight polyethylene fiber. Other nucleating agents can be measured according to special elements (such as sulfur or nitrogen) in the nucleating agent.

[0027] A second aspect of the present invention provides a method for preparing an ultra-high molecular weight polyethylene fiber, comprising the following steps:

[0028] (1) mixing an ultra-high molecular weight polyethylene raw material, a solvent I and an additive I to obtain a mixed solution;

[0029] (2) mixing the mixed solution, auxiliary agent II, nucleating agent and solvent II, spinning and pre-stretching to obtain primary jelly filaments;

[0030] The auxiliary agent II contains a coupling agent and an initiator;

[0031] (3) After removing the solvent from the primary jelly silk, the silk is subjected to a heat drawing treatment.

[0032] According to the present invention, the ultra-high molecular weight polyethylene raw material can be purchased from a commercial source or can be prepared at home. Moreover, the ultra-high molecular weight polyethylene raw material can be a powder or a granular raw material, preferably a powder.

[0033] During the research process, the inventors found that the method provided by the present invention, by adding a coupling agent, an initiator and a nucleating agent during the spinning process, can facilitate subsequent drawing through the interaction between the coupling agent, the initiator, the nucleating agent and the spinning solution, so that the prepared fiber has a smaller fineness; at the same time, it can also prevent the fiber from breaking under conditions of high drawing ratios, effectively improving the tensile breaking strength of the fiber; it can also effectively reduce the creep elongation of the fiber, improve the creep resistance of the fiber, so that the fiber can have the advantages of thin diameter, high tensile breaking strength and creep resistance.

[0034] Preferably, in step (1), the auxiliary agent I contains a dispersant. The addition of the dispersant can make the ultra-high molecular weight polyethylene raw material fully dissolved in the solvent, and promote its molecular weight to fully develop, reduce the spinning viscosity, reduce the spinning time, ensure that the spinning is carried out continuously, quickly and stably, improve the spinning efficiency, and improve the uniformity of the fiber obtained by spinning. Considering that the spinning efficiency can be further improved, preferably, relative to 100g of the ultra-high molecular weight polyethylene raw material, the amount of the dispersant is 3-20g, specifically 3g, 5g, 10g, 15g, 20g, or any value between these values, and the amount of the solvent I is 200-2000g, specifically 200g, 500g, 1000g, 1500g, 2000g, or any value between these values.

[0035] Preferably, the dispersant is selected from at least one of triethylhexyl phosphoric acid, sodium lauryl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, guar gum and fatty acid polyethylene glycol esters. Specifically, the cellulose derivative can be cellulose nitrate and / or carboxymethyl cellulose, and the fatty acid polyethylene glycol ester can be laurate and / or stearate. The use of the above dispersant can further improve the dispersion effect of the ultra-high molecular weight polyethylene raw material in the solvent I, thereby improving the spinning efficiency and making the prepared fiber more uniform. In view of being able to further improve the uniformity of the fiber, it is further preferred that the dispersant is selected from triethylhexyl phosphoric acid and / or polyacrylamide.

[0036] Preferably, the solvent I is selected from at least two of paraffin oil, ethylene glycol and mineral oil. By limiting the solvent I to the above range, the dispersion effect of the ultra-high molecular weight polyethylene raw material in the solvent I can be improved, thereby improving the spinning efficiency and making the prepared fiber more uniform. Further preferably, the solvent I is a mixture of paraffin oil and ethylene glycol, and the mixing volume ratio of paraffin oil and ethylene glycol is 2-9:1.

[0037] Preferably, the step (1) further comprises: subjecting the mixed liquid phase to a shear treatment. The shear treatment method can make the ultra-high molecular weight polyethylene raw material dissolve more completely in the solvent I, promote its molecular weight to fully develop, reduce the spinning viscosity, reduce the spinning time, ensure that the spinning is carried out continuously, rapidly and stably, improve the spinning efficiency, and improve the uniformity of the spun fibers.

[0038] In order to further improve the uniformity of the obtained fiber, preferably, the shearing treatment includes at least two shearings, and the stirring rate of the latter shearing is greater than the stirring rate of the previous shearing. Specifically, when the shearing treatment includes two shearings, the stirring rate of the second shearing is greater than the stirring rate of the first shearing, and the stirring rate of the first shearing can be determined by the test personnel according to the actual test situation. Preferably, in order to further improve the uniformity of the fiber obtained by spinning, the stirring rate of the first shearing is 70-110 rpm, and the difference between the stirring rates of the two adjacent shearings is 20-80 rpm.

[0039] More preferably, the shearing treatment includes three shearing steps; wherein the conditions for the first shearing step at least include: a stirring speed of 70-110 rpm, specifically 70 rpm, 80 rpm, 90 rpm, 100 rpm, 110 rpm, or any value therebetween; a time of 30-60 min, specifically 30 min, 40 min, 50 min, 60 min, or any value therebetween; and a second shearing step at least includes: a stirring speed of 130-170 rpm, specifically 130 rpm, 140 rpm, 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm, 200 rpm, 210 rpm, 220 rpm, 230 rpm, 240 rpm, 250 rpm, 260 rpm, 270 rpm, 280 rpm, 290 rpm, 300 rpm, 310 rpm, 320 rpm, 330 rpm, 340 rpm, 350 rpm, 360 rpm, 370 rpm, 380 rpm, 390 rpm, 400 rpm, 410 rpm, 420 rpm, 430 rpm, 440 rpm, 450 rpm, 460 rpm, 470 rpm, 480 rpm, 490 rpm, 500 rpm, 510 rpm, 520 rpm, 530 rpm, 540 rpm, 550 rpm, 560 rpm, 570 rpm, 580 rpm, 590 rpm, 60 rpm, 170 rpm, or any value between these values; the time is 30-60 min, specifically 30 min, 40 min, 50 min, 60 min, or any value between these values; the conditions for the third shearing at least include: the stirring speed is 180-220 rpm, specifically 180 rpm, 190 rpm, 200 rpm, 210 rpm, 220 rpm, or any value between these values; the time is 30-60 min, specifically 30 min, 40 min, 50 min, 60 min, or any value between these values. The uniformity of the fiber prepared under the above conditions is better.

[0040] Preferably, in step (2), relative to 100g of the ultra-high molecular weight polyethylene raw material, the amount of the coupling agent is 1.5-10g, specifically 1.5g, 3g, 5g, 8g, 10g, or any value between these values; the amount of the initiator is 1.5-10g, specifically 1.5g, 3g, 5g, 8g, 10g, or any value between these values; the amount of the nucleating agent is 5-20g, specifically 5g, 10g, 15g, 20g, or any value between these values. The fiber prepared under the above conditions has a smaller fineness, a higher tensile strength and better creep resistance. Further preferably, relative to 100g of the ultra-high molecular weight polyethylene raw material, the amount of the coupling agent is 1.5-2g, the amount of the initiator is 1.5-2g, and the amount of the nucleating agent is 6-8g.

[0041] In order to further improve the creep resistance of the prepared fiber, preferably, the auxiliary agent II also contains an antioxidant. In order to further improve the creep resistance of the fiber, preferably, the amount of the antioxidant is 1.5-10g relative to 100g of the ultra-high molecular weight polyethylene raw material. Further preferably, the amount of the antioxidant is 1.5-2g relative to 100g of the ultra-high molecular weight polyethylene raw material.

[0042] According to the present invention, preferably, the antioxidant is selected from at least one of tris(2,4-di-tert-butylphenyl)phosphite, pentaerythritol ester, pentaerythritol, and diphosphite. The coupling agent is selected from at least one of silane coupling agent, titanate coupling agent, and aluminate coupling agent. The initiator is a peroxide organic initiator. The combination of the above-mentioned antioxidant, coupling agent, and initiator can effectively reduce the diameter of the fiber and improve the tensile strength and creep resistance of the fiber. More preferably, the peroxide organic initiator is selected from at least one of benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide, and diisopropylbenzene peroxide.

[0043] More preferably, the antioxidant is pentaerythritol and / or diphosphite, the coupling agent is a titanate coupling agent and / or a silane coupling agent, and the initiator is lauroyl peroxide and / or di-tert-butyl peroxide.

[0044] Preferably, in step (2), the nucleating agent is a β-crystal nucleating agent. Specifically, the β-crystal nucleating agent may be an inorganic β-crystal nucleating agent and / or an organic β-crystal nucleating agent. Preferably, the β-crystal nucleating agent is an inorganic β-crystal nucleating agent and an organic β-crystal nucleating agent, the inorganic β-crystal nucleating agent may be selected from at least one of calcium carbonate, calcium sulfate and yttrium oxide, the inorganic β-crystal nucleating agent may also be a rare earth compound, the rare earth compound may be a compound composed of rare earth elements and other elements, specifically a lanthanide compound and / or a cerium compound, the lanthanide compound may be lanthanum chloride and / or lanthanum carbonate, the cerium compound may be cerium chloride. The organic β-crystal nucleating agent may be selected from at least one of phenanthrene, anthracene, 2-mercaptobenzimidazole, triphenoldithiazine, dicarboxylate, aromatic diamide and TMB-5. The use of a β-crystal nucleating agent can induce instability in the interface between the nucleating agent and the polyethylene phase during further crystallization during the hot drawing process, generate more crystallization nuclei, increase the number of nucleations, and then reduce the grain size, increase the fiber hot drawing ratio without breaking, and significantly improve the tensile strength and creep resistance of the fiber. At the same time, the diameter of the obtained fiber can also be significantly reduced. Considering that the tensile strength and creep resistance of the fiber can be further improved and the diameter of the fiber can be reduced, it is further preferred that the nucleating agent is calcium carbonate and 2-mercaptobenzimidazole. More preferably, the mass ratio of the calcium carbonate to the 2-mercaptobenzimidazole is 1:0.5-2.

[0045] Preferably, the pre-stretching conditions at least include: the drafting multiple is 5-8 times, specifically 5 times, 6 times, 7 times, 8 times, or any value in between. The fiber prepared under the above conditions has higher breaking strength and better creep resistance.

[0046] According to the present invention, the mixing in step (2) is carried out in a screw extruder, which can be a single screw extruder or a twin screw extruder. Preferably, the screw extruder is a twin screw extruder, and more preferably a pressurized twin screw extruder. During the mixing process, the pressure of the mixture in the pressurized twin screw extruder is maintained at 6-15 MPa, which can further improve the breaking strength and creep resistance of the fiber.

[0047] According to the present invention, in step (2), pre-stretching can be achieved by any machine or structure capable of achieving pre-stretching. Preferably, pre-stretching is achieved by a spinneret and a spinning box.

[0048] According to the present invention, preferably, the method further comprises cooling the material obtained after the pre-stretching treatment; the cooling treatment can be carried out under any feasible conditions. As a specific embodiment of the present invention, the cooling treatment is carried out in a cooling water bath. Specifically, the cooling treatment conditions include: a temperature of 0-20°C and a time of 3-10s.

[0049] According to the present invention, the solvent II may be at least one of paraffin oil, ethylene glycol and mineral oil. Preferably, the solvent II is paraffin oil.

[0050] Preferably, in step (3), the conditions of the hot drawing include at least: the drawing ratio is 40-60 times, specifically 40 times, 45 times, 50 times, 55 times, 60 times, or any value in between these values, and the temperature is 120-160°C, specifically 120°C, 130°C, 140°C, 150°C, 160°C, or any value in between these values. The fiber prepared under the above hot drawing conditions has a thinner diameter, higher tensile strength and creep resistance.

[0051] According to the present invention, in step (3), desolventizing can be achieved by any feasible method. Preferably, desolventizing is achieved by extraction with an extracting liquid and drying. The selection of the extracting liquid, the extraction conditions and the drying conditions can be determined by those skilled in the art according to actual conditions.

[0052] According to the present invention, the amount of solvent II added can be determined by the experimenter according to the actual situation. As a specific embodiment of the present invention, relative to 100g of ultra-high molecular weight polyethylene raw material, the amount of solvent II added is 15-150g.

[0053] The third aspect of the present invention provides an application of the ultra-high molecular weight polyethylene fiber provided in the first aspect or the ultra-high molecular weight polyethylene fiber prepared by the preparation method provided in the second aspect in bulletproof fabrics.

[0054] The ultra-high molecular weight polyethylene fiber can ensure the tensile strength and anti-creep performance of the fiber while ensuring a thin diameter, and can be better applied to bulletproof fabrics.

[0055] Preferably, the textile fabric is a bulletproof vest.

[0056] According to a particularly preferred embodiment of the present invention, a method for preparing ultra-high molecular weight polyethylene fiber is provided, comprising the following steps:

[0057] (1) stirring an ultra-high molecular weight polyethylene powder, a solvent I and a dispersant together and adding them into a dissolving kettle, and subjecting them to multi-stage shearing (the conditions of the first shearing include: a stirring speed of 70-110 rpm and a time of 30-60 min; the conditions of the second shearing include: a stirring speed of 130-170 rpm and a time of 30-60 min; the conditions of the third shearing include: a stirring speed of 180-220 rpm and a time of 30-60 min) to obtain a spinning solution;

[0058] The dispersant is selected from at least one of triethylhexyl phosphoric acid, sodium lauryl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, guar gum and fatty acid polyethylene glycol esters; the solvent I is selected from at least two of paraffin oil, ethylene glycol and mineral oil;

[0059] Relative to 100g of the ultra-high molecular weight polyethylene raw material, the amount of the dispersant is 3-20g, and the amount of the solvent I is 200-2000g;

[0060] (2) The spinning solution enters a pressurized twin-screw extruder, and a mixture of an antioxidant, a coupling agent, an initiator, a nucleating agent and paraffin oil is introduced for spinning. After pre-stretching treatment (stretching multiple is 5-8 times) by a spinneret and a spinning box, it is cooled (temperature is 0-20° C., time is 3-10 seconds) to obtain primary jelly filaments;

[0061] The antioxidant is selected from at least one of tris(2,4-di-tert-butylphenyl)phosphite, pentaerythritol ester, pentaerythritol, and diphosphite; the coupling agent is selected from at least one of silane coupling agent, titanate coupling agent, and aluminate coupling agent; the initiator is selected from at least one of benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide, and diisopropylbenzene peroxide; the nucleating agent is a β-crystalline nucleating agent;

[0062] Relative to 100g of the ultra-high molecular weight polyethylene raw material, the amount of the coupling agent is 1.5-10g, the amount of the initiator is 1.5-10g, the amount of the nucleating agent is 5-20g, and the amount of the antioxidant is 1.5-10g.

[0063] (3) After the nascent gel fibers are extracted with an extractant to remove the solvent and dried, they are subjected to multi-stage hot drawing (drawing ratio of 40-60 times, temperature of 120-160°C) to obtain ultra-high molecular weight polyethylene fibers.

[0064] The ultra-high molecular weight polyethylene fiber prepared by the above method can ensure the tensile strength and anti-creep performance of the fiber while ensuring a thin diameter.

[0065] The present invention will be described in detail below through examples. In the following examples, ultra-high molecular weight polyethylene powder was purchased from Shenzhen Teli New Material Technology Co., Ltd., with a molecular weight of 4.5 million (density of 0.98 g / cm 3 ), molecular weight is 3 million (density is 0.97g / cm 3 ); aluminate coupling agent was purchased from Dongguan Dinghai Chemical Co., Ltd., product model DL-411; pentaerythritol ester was purchased from Shanghai Huijun Chemical Co., Ltd., product model PETO; titanate coupling agent was purchased from Dongguan Dinghai Chemical Co., Ltd., product model NDZ-201; silane coupling agent was purchased from Kangjin Chemical Co., Ltd., product model 560; diphosphite was purchased from Li'anlong Chemical Co., Ltd., product model RIANOX-686.

[0066] Creep elongation: Using the hanging weight method, 1.5m long parallel fibers are placed in an environmental chamber for creep performance testing. The hanging weight is 20% of the single fiber breaking strength, the hanging time is 48h, and the test temperature is 50℃.

[0067] Tensile strength at break: measured using the method mentioned in GB / T 14344-2008.

[0068] Fineness: The fiber density is tested by GB / T14335, and the fiber length is tested by GB / T14336. The fiber fineness is calculated by the detected density and length.

[0069] Example 1

[0070] (1) Ultra-high molecular weight polyethylene powder (molecular weight 4.5 million, molecular weight 0.98 g / cm 3 ), a mixed solvent of dispersant triethylhexyl phosphoric acid, paraffin oil and ethylene glycol (volume ratio of 7:3) is stirred together at a mass ratio of 5:1:94 and added into a dissolving kettle, and subjected to multi-stage shearing, with the first stage stirring speed being 70 rpm, the second stage stirring speed being 130 rpm, the third stage stirring speed being 180 rpm, and the stirring time of each stage being 30 min, and the spinning solution is obtained after the stirring is completed;

[0071] (2) The spinning solution enters a pressurized twin-screw extruder, and the melt pressure in the screw is maintained at 6 MPa. A mixture of an antioxidant pentaerythritol ester, an initiator benzoyl peroxide, an aluminate coupling agent, a mixture of a β-crystal nucleating agent calcium carbonate and paraffin oil in a mass ratio of 100:10 (spinning solution: a mixture of an antioxidant pentaerythritol ester, an initiator benzoyl peroxide, an aluminate coupling agent, a β-crystal nucleating agent calcium carbonate and paraffin oil in a mass ratio of 1:1:1:2:15 is introduced, and a spinning treatment is performed. The spinning solution is pre-stretched by a spinneret and a spinning box, and the pre-stretching ratio is 5 times. The primary gel filaments are then cooled (temperature is 20°C, time is 10s) to obtain the primary gel filaments.

[0072] (3) After the nascent gel fibers are extracted with an extracting liquid to remove the solvent and dried, they are subjected to multi-stage hot drawing with a drawing multiple of 40 times and a drawing temperature of 120°C. After the drawing is completed, ultra-high molecular weight polyethylene fibers are obtained.

[0073] Example 2

[0074] (1) Ultra-high molecular weight polyethylene powder (molecular weight 3 million, molecular weight 0.97 g / cm 3 ), a mixed solvent of dispersant sodium dodecyl sulfate, paraffin oil and mineral oil in a mass ratio of 30:1:69 is stirred together and added into a dissolving kettle, and subjected to multi-stage shearing, with the first stage stirring speed being 90 rpm, the second stage stirring speed being 150 rpm, the third stage stirring speed being 200 rpm, and the stirring time of each stage being 60 min, and the spinning solution is obtained after the stirring is completed;

[0075] (2) the spinning solution enters a pressurized twin-screw extruder, the melt pressure in the screw is maintained at 15 MPa, and a mixture of an antioxidant pentaerythritol, an initiator lauroyl peroxide, a titanate coupling agent, a mixture of a β-crystal nucleating agent 2-mercaptobenzimidazole and paraffin oil in a mass ratio of 100:10 (spinning solution: a mixture of an antioxidant pentaerythritol, an initiator lauroyl peroxide, a titanate coupling agent, a β-crystal nucleating agent 2-mercaptobenzimidazole and paraffin oil in a mass ratio of 1:1:1:5:12 is introduced, and a spinning treatment is performed, and a pre-stretching treatment is performed by a spinneret and a spinning box, and the pre-stretching ratio is 8 times, and then a cooling treatment (temperature is 15°C, time is 8s) is performed to obtain primary jelly filaments;

[0076] (3) After the nascent gel fibers are extracted with an extracting liquid to remove the solvent and dried, they are subjected to multi-stage hot drawing with a drawing multiple of 60 times and a drawing temperature of 160°C. After the drawing is completed, ultra-high molecular weight polyethylene fibers are obtained.

[0077] Example 3

[0078] (1) Ultra-high molecular weight polyethylene powder (molecular weight 4.5 million, molecular weight 0.98 g / cm 3), a mixed solvent of dispersant polyacrylamide, paraffin oil ethylene glycol and mineral oil in a mass ratio of 30:1:69 is stirred together and added into a dissolving kettle, and subjected to multi-stage shearing, with the first stage stirring speed being 110 rpm, the second stage stirring speed being 170 rpm, the third stage stirring speed being 220 rpm, and the stirring time of each stage being 45 min, and the spinning solution is obtained after the stirring is completed;

[0079] (2) the spinning solution enters a pressurized twin-screw extruder, the melt pressure in the screw is maintained at 10 MPa, and the spinning solution is pre-stretched by a spinneret and a spinning box, the pre-stretching ratio is 7 times, and a mixture of an antioxidant diphosphite, an initiator di-tert-butyl peroxide, a silane coupling agent, a β-crystal nucleating agent TMB-5 and a paraffin oil in a mass ratio of 100:10 (spinning solution: a mixture of an antioxidant diphosphite, an initiator di-tert-butyl peroxide, a silane coupling agent, a β-crystal nucleating agent TMB-5 and a paraffin oil in a mass ratio of 1:1:1:4:13 is introduced, and the spinning process is performed, and then the primary gel filaments are obtained by cooling the filaments (temperature is 0°C, time is 3s);

[0080] (3) After the nascent gel fibers are extracted with an extracting liquid to remove the solvent and dried, they are subjected to multi-stage hot drawing with a drawing multiple of 50 times and a drawing temperature of 140°C. After the drawing is completed, ultra-high molecular weight polyethylene fibers are obtained.

[0081] Example 4

[0082] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that the calcium carbonate in step (2) was replaced by nano carbon black.

[0083] Example 5

[0084] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that the antioxidant pentaerythritol ester was not added in step (2).

[0085] Example 6

[0086] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that the dispersant polyacrylamide in step (1) was replaced by an antioxidant pentaerythritol ester, and the antioxidant pentaerythritol ester was not added in step (2).

[0087] Example 7

[0088] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that the initiator benzoyl peroxide was replaced by potassium persulfate.

[0089] Example 8

[0090] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that step (1) was replaced by: ultra-high molecular weight polyethylene powder, dispersant polyacrylamide, a mixed solvent of paraffin oil ethylene glycol and mineral oil in a mass ratio of 5:1:94 were stirred together and added to a dissolving kettle, and sheared for 30 minutes at a stirring speed of 70 rpm to obtain a spinning solution.

[0091] Example 9

[0092] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that the calcium carbonate in step (2) was replaced by a mixture of calcium carbonate and 2-mercaptobenzimidazole in a mass ratio of 1:1.

[0093] Example 10

[0094] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that the calcium carbonate in step (2) was replaced by a mixture of calcium carbonate and 2-mercaptobenzimidazole in a mass ratio of 1:0.5.

[0095] Embodiment 11

[0096] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that the calcium carbonate in step (2) was replaced by a mixture of calcium carbonate and 2-mercaptobenzimidazole in a mass ratio of 1:2.

[0097] Example 12

[0098] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that the calcium carbonate in step (2) was replaced by a mixture of calcium carbonate and 2-mercaptobenzimidazole in a mass ratio of 1:0.1.

[0099] Embodiment 13

[0100] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that the calcium carbonate in step (2) was replaced by a mixture of calcium carbonate and 2-mercaptobenzimidazole in a mass ratio of 1:3.

[0101] Comparative Example 1

[0102] Ultra-high molecular weight polyethylene fibers were prepared according to the method of Example 1, except that no nucleating agent calcium carbonate was added in step (2).

[0103] Comparative Example 2

[0104] Ultra-high molecular weight polyethylene fiber was prepared according to the method of Example 1, except that no aluminate coupling agent and no nucleating agent calcium carbonate were added in step (2).

[0105] Comparative Example 3

[0106] Ultra-high molecular weight polyethylene fiber was prepared according to the method of Example 1, except that no aluminate coupling agent was added in step (2).

[0107] Comparative Example 4

[0108] Ultra-high molecular weight polyethylene fiber was prepared according to the method of Example 1, except that no initiator benzoyl peroxide was added in step (2).

[0109] like Figure 1 As shown in the figure, the crystal morphology of the ultra-high molecular weight polyethylene obtained in Example 1 and Comparative Example 1 is polarized light microscope (the polarizing microscope was purchased from Shanghai Wumo Optical Instrument Co., Ltd., model WMP-6880). It can be seen from the figure that the crystal size of the UHMWPE after adding the nucleating agent becomes smaller, the number of grains increases, and it can induce instability at the interface between the nucleating agent and the polyethylene phase during further crystallization in the hot stretching process, generate more crystallization nuclei, increase the number of nucleations, and thus reduce the grain size, increase the fiber hot stretching ratio without breaking, effectively reduce the fiber diameter, and at the same time improve the fiber tensile strength.

[0110] like Figure 2 As shown, the surface of the fiber prepared in Example 1 becomes rough, which indicates that the chemical reaction of the fiber leads to the transformation of the surface morphology.

[0111] like Figure 3 As shown, under a higher temperature environment, the fiber prepared in Example 1 exhibits excellent creep resistance, indicating that the interaction force between molecular chains is enhanced.

[0112] The performance of the ultra-high molecular weight polyethylene fibers prepared in the examples and comparative examples was tested, and the results are shown in Table 1.

[0113] Table 1 Performance test table of ultra-high molecular weight polyethylene fibers obtained in the examples and comparative examples

[0114]

[0115]

[0116] As shown in Table 1, the prepared UHMWPE fiber after crystallization regulation and chemical crosslinking has an ultra-low fineness between 5.5D-30D, a tensile breaking strength of more than 350N / tex, and a creep elongation of less than 3%; while the unmodified UHMWPE fiber (Comparative Example 2) has a low strength and poor anti-creep effect. It can be seen from the above data of the comparative example and the comparative example that the simultaneous introduction of the nucleating agent, the coupling agent and the initiator can obtain an ultra-fine denier UHMWPE fiber material with low creep and high tensile breaking strength.

[0117] 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. An ultra-high molecular weight polyethylene fiber, It is characterized in that The fiber fineness is less than or equal to 30D, the tensile strength at break of the fiber is greater than or equal to 350N / tex, and the creep elongation of the fiber at 50°C is less than or equal to 3%.

2. The ultra-high molecular weight polyethylene fiber according to claim 1, It is characterized in that The tensile breaking strength of the fiber is 350-500N / tex, and the fineness of the fiber is less than or equal to 10D; Preferably, the tensile breaking strength of the fiber is 370-400 N / tex, and the creep elongation of the fiber at 50° C. is less than or equal to 2.1%.

3. The ultra-high molecular weight polyethylene fiber according to claim 1 or 2, It is characterized in that The fiber contains a nucleating agent; Preferably, the nucleating agent is a β-crystal nucleating agent, and the β-crystal nucleating agent is an inorganic β-crystal nucleating agent and / or an organic β-crystal nucleating agent; Preferably, the β-crystal nucleating agent is an inorganic β-crystal nucleating agent and an organic β-crystal nucleating agent, the inorganic β-crystal nucleating agent is selected from at least one of calcium carbonate, calcium sulfate and yttrium oxide, and the organic β-crystal nucleating agent is selected from at least one of phenanthrene, anthracene, 2-mercaptobenzimidazole, triphenol dithiazine, dicarboxylate, aromatic diamide and TMB-5; Preferably, the content of the nucleating agent in the fiber is 1-11 mass %.

4. A method for preparing ultra-high molecular weight polyethylene fiber, It is characterized in that The steps include: (1) mixing an ultra-high molecular weight polyethylene raw material, a solvent I and an additive I to obtain a mixed solution; (2) mixing the mixed solution, auxiliary agent II, nucleating agent and solvent II, spinning and pre-stretching to obtain primary jelly filaments; The auxiliary agent II contains a coupling agent and an initiator; (3) After removing the solvent from the primary jelly silk, the silk is subjected to a heat drawing treatment.

5. The preparation method according to claim 4, It is characterized in that In step (1), the auxiliary agent I contains a dispersant; Preferably, relative to 100g of the ultra-high molecular weight polyethylene raw material, the amount of the dispersant is 3-20g, and the amount of the solvent I is 200-2000g; Preferably, the dispersant is selected from at least one of triethylhexylphosphoric acid, sodium lauryl sulfate, methylpentyl alcohol, cellulose derivatives, polyacrylamide, guar gum and polyethylene glycol esters of fatty acids; The solvent I is selected from at least two of paraffin oil, ethylene glycol and mineral oil.

6. The preparation method according to claim 4, It is characterized in that Step (1) further comprises: subjecting the mixed liquid phase to shear treatment; Preferably, the shearing treatment includes at least two shearing steps, and the shearing stirring rate of the latter step is greater than the shearing stirring rate of the former step; Preferably, the shearing process includes three shearing steps; wherein: The conditions of the first shearing include at least: a stirring speed of 70-110 rpm and a time of 30-60 min; The conditions of the second shearing include at least: a stirring speed of 130-170 rpm and a time of 30-60 min; The conditions for the third shearing include at least: a stirring speed of 180-220 rpm and a time of 30-60 min.

7. The preparation method according to any one of claims 4 to 6, It is characterized in that In step (2), relative to 100 g of the ultra-high molecular weight polyethylene raw material, the amount of the coupling agent is 1.5-10 g, the amount of the initiator is 1.5-10 g, and the amount of the nucleating agent is 5-20 g; Preferably, the auxiliary agent II also contains an antioxidant; Preferably, relative to 100g of the ultra-high molecular weight polyethylene raw material, the amount of the antioxidant is 1.5-10g; Preferably, the antioxidant is selected from at least one of tris(2,4-di-tert-butylphenyl)phosphite, pentaerythritol ester, pentaerythritol, and diphosphite; The coupling agent is selected from at least one of a silane coupling agent, a titanate coupling agent and an aluminate coupling agent; The initiator is selected from at least one of benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide and dicumyl peroxide.

8. The preparation method according to any one of claims 4 to 6, It is characterized in that In step (2), the nucleating agent is a β-crystal nucleating agent, and the β-crystal nucleating agent is an inorganic β-crystal nucleating agent and / or an organic β-crystal nucleating agent; Preferably, the β-crystal nucleating agent is an inorganic β-crystal nucleating agent and an organic β-crystal nucleating agent, the inorganic β-crystal nucleating agent is selected from at least one of calcium carbonate, calcium sulfate and yttrium oxide, and the organic β-crystal nucleating agent is selected from at least one of phenanthrene, anthracene, 2-mercaptobenzimidazole, triphenol dithiazine, dicarboxylate, aromatic diamide and TMB-5; Preferably, the nucleating agent is calcium carbonate and 2-mercaptobenzimidazole; Preferably, the mass ratio of the calcium carbonate to the 2-mercaptobenzimidazole is 1:0.5-2.

9. The preparation method according to any one of claims 4 to 6, It is characterized in that In step (2), the pre-stretching conditions include at least: a drafting multiple of 5-8 times; The method further comprises cooling the material obtained after the pre-stretching treatment; In step (3), the conditions for the hot stretching include at least: a stretching ratio of 40-60 times and a temperature of 120-160°C.

10. Use of the ultra-high molecular weight polyethylene fiber according to any one of claims 1 to 3 or the ultra-high molecular weight polyethylene fiber prepared by the preparation method according to any one of claims 4 to 9 in bulletproof fabrics; Preferably, the bulletproof fabric is a bulletproof vest.

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