Ultra-high molecular weight polyethylene fibers and methods of making and using the same

Abstract

The present application relates to polyethylene fiber, disclose a kind of ultra-high molecular weight polyethylene fiber and its preparation method and application.The fiber fineness is less than or equal to 30D, tensile breaking strength is greater than or equal to 350N / tex, and creep elongation is less than or equal to 3%.The preparation method includes the following steps: (1) ultra-high molecular weight polyethylene raw material, solvent I and auxiliary I are mixed, and the mixed solution is obtained;(2) after the mixed solution, auxiliary II, nucleating agent and solvent II are mixed, spinning, pre-drawing is carried out, and the nascent gel silk is obtained;The auxiliary II contains coupling agent and initiator;(3) after the nascent gel silk is desolventized, it is handled by heat drawing.The ultra-high molecular weight polyethylene fiber not only has smaller fineness, also has greater strength and smaller creep elongation, can have the advantages of fine diameter, high strength and good anti-creep performance.

Description

TECHNICAL FIELD

[0001] The present application relates to polyethylene fibers, in particular to a kind of ultra-high molecular weight polyethylene fiber and its preparation method and application. BACKGROUND

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber is one of the three high-performance fibers in the world, which has many excellent properties. Because UHMWPE fiber has high specific strength, high specific modulus, excellent impact resistance and good wear resistance, it can also resist the corrosion of strong acid, strong alkali and other chemicals, and has high electromagnetic wave transmission rate, low friction coefficient, non-water absorption and good biocompatibility. Therefore, UHMWPE fiber is widely used in military protective materials, aerospace related materials, medical materials, radar antenna covers, ship anchor ropes and many other fields.

[0003] Fine denier ultra-high molecular weight polyethylene fiber can be woven into soft and comfortable high-grade textiles, which can be applied in soft protective products and wearable clothing, home textiles and other fields, and has high economic value. At present, the preparation method of fine denier ultra-high molecular weight polyethylene fiber usually adopts conventional wet spinning. From the factors of production cost and efficiency, it is determined that there is a higher solvent residue in the fiber product, and the single fiber fineness is more than 2.5 dtex, the texture is coarse and hard, and the hand feeling is rough, which limits its application and development in soft individual protection and other clothing fields. Although the fiber prepared by using volatile solvents such as naphthane and xylene in dry gel spinning has the advantages of low solvent residue, low extrusion temperature, large nozzle stretching ratio and the like, it is easier to prepare ultra-fine denier and high-strength polyethylene fiber, but there are problems such as poor spinning process stability and poor creep resistance. SUMMARY

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

[0005] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a kind of ultra-high molecular weight polyethylene fiber, the fineness of the fiber is less than or equal to 30D, the tensile breaking strength of the fiber is greater than or equal to 350N / tex, and the creep elongation of the fiber at 50 DEG C is less than or equal to 3%.

[0006] The second aspect of the present application provides a kind of preparation method of ultra-high molecular weight polyethylene fiber, which comprises the following steps:

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

[0008] (2) mixing the mixed solution, the auxiliary agent II, the nucleating agent and the solvent II, and then performing spinning and pre-drawing to obtain a primary frozen gel yarn;

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

[0010] (3) removing the solvent from the primary frozen gel yarn and performing heat drawing treatment.

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

[0012] By the above technical solution, the present application has the following beneficial effects:

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

[0014] (2) The method provided by the present application can facilitate subsequent drawing by adding a coupling agent, an initiator and a nucleating agent in the spinning process through the interaction between the coupling agent, the initiator, the nucleating agent and the to-be-spun solution, so that the prepared fiber has a smaller fineness; at the same time, the tensile breaking strength of the fiber can be effectively improved, the creep elongation of the fiber can be reduced, the anti-creep performance of the fiber can be improved, and the fiber can have the advantages of fine diameter, high tensile breaking strength and anti-creep. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A crystalline morphology diagram of the ultra-high molecular weight polyethylene fiber prepared in Example 1 and Comparative Example 1 of the present application;

[0016] Figure 2 A surface electron microscope diagram of the ultra-high molecular weight polyethylene fiber prepared in Example 1(B) and Comparative Example 2(A) of the present application;

[0017] Figure 3 The fiber creep elongation of the ultra-high molecular weight polyethylene fiber prepared in Example 1(B) and Comparative Example 2(A) of the present application was tested by the suspended weight method at 50℃. DETAILED DESCRIPTION

[0018] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. Any numeric range recited is intended to include all values from the lower value to the upper value, inclusive of both values, and to also include any value approximately or about the value. For numeric ranges, the endpoints are included in the ranges, are included between the endpoints, and the individual endpoints can be combined with other endpoints to form new numeric ranges, which are to be considered as being specifically disclosed herein.

[0019] As previously described, the first aspect of the present application provides an ultra-high molecular weight polyethylene fiber, the fiber having a fineness of less than or equal to 30D, the fiber having a tensile breaking strength of greater than or equal to 350N / tex, and the fiber having a creep elongation of less than or equal to 3% at 50°C.

[0020] According to the present application, the ultra-high molecular weight polyethylene refers to a polyethylene having a molecular weight of more than 1 million, preferably, the ultra-high molecular weight polyethylene has a molecular weight of 1 million to 8 million, and further preferably, the ultra-high molecular weight polyethylene has a density of 0.97 to 0.98 g / cm 3 .

[0021] The density of the fiber is tested by GB / T14335, the length of the fiber is tested by GB / T14336, and the fineness of the fiber is calculated based on the tested density and length. The tensile breaking strength is tested by GB / T14344-2008. Generally, the higher the temperature, the worse the creep resistance of the fiber, that is, the fiber has a poor creep resistance at a higher temperature. According to the present application, the creep elongation is tested by the suspended weight method, the parallel fiber having a length of 1.5 m is placed in an environmental chamber, and the creep resistance is tested, the suspended weight is 20% of the breaking strength of the single fiber, the suspended weight time is 48 h, and the test temperature is 50°C, that is, the fiber has a creep elongation of less than or equal to 3% at the suspended weight of 20% of the breaking strength of the single fiber and the temperature of 50°C.

[0022] The ultra-high molecular weight polyethylene fiber provided by the present application can ensure the tensile breaking strength of the fiber and the creep resistance of the fiber while ensuring the fine diameter, can ensure the comfort during use, and is not easy to break and deform.

[0023] According to the present application, preferably, the tensile breaking strength of the fiber is 350-500 N / tex, specifically 350 N / tex, 400 N / tex, 450 N / tex, 500 N / tex, or any value between these values; the fiber has a fineness of less than or equal to 10D. Under the above conditions, the fiber has a smaller diameter and higher comfort during use. Further preferably, the tensile breaking strength of the fiber is greater than 370-400 N / tex, and the creep elongation of the fiber at 50℃ is less than or equal to 2.1%. The fiber under the above conditions has higher tensile breaking strength and better creep resistance, is less likely to break during use, and is less likely to deform. Further preferably, the tensile breaking strength of the fiber is 370-380 N / tex.

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

[0025] Preferably, the nucleating agent is a β crystal nucleating agent, which is an inorganic β crystal nucleating agent and / or an organic β crystal nucleating agent; the β crystal nucleating agent can further induce interface instability between the nucleating agent and the polyethylene phase, produce more crystal nuclei, increase the number of nucleation, and thus reduce the grain size, increase the thermal drawing ratio of the fiber without breaking, significantly improve the tensile breaking strength and creep resistance of the fiber, and also significantly reduce the diameter of the prepared fiber. In order to further improve the tensile breaking strength, creep resistance and reduce the diameter of the fiber, further 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. More preferably, the content of the nucleating agent in the fiber is 1-11 mass%, and further preferably 5-11 mass%.

[0026] According to the present application, the nucleating agent can be detected by XRD and corresponding standard spectrum of different nucleating agents, and then the content of each nucleating agent is measured by selecting a suitable method according to the type of each nucleating agent, such as the test method of inorganic β crystal nucleating agent or nucleating agent with a melting point greater than or equal to 150℃: dissolve a fixed amount of ultra-high molecular weight polyethylene fiber at 120℃ with decahydronaphthalene, filter to obtain a solid phase, dry and weigh, and calculate the content of the nucleating agent in the fiber from 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 in the nucleating agent (such as sulfur or nitrogen elements).

[0027] The second aspect of the present application provides a preparation method of 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, an additive II, a nucleating agent and a solvent II, and then performing spinning and pre-drawing to obtain a primary gel spinning yarn;

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

[0031] (3) removing the solvent from the primary gel spinning yarn and then performing heat drawing treatment.

[0032] According to the present application, the ultra-high molecular weight polyethylene raw material can be obtained by commercial purchase or self-preparation. Moreover, the ultra-high molecular weight polyethylene raw material can be a powder or a granular raw material, and is preferably a powder.

[0033] The inventors have found in the research process that the method provided by the present application 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, the fiber can not be broken under the condition of high drawing ratio, effectively improving the tensile breaking strength of the fiber. The method can also effectively reduce the creep elongation of the fiber and improve the anti-creep performance of the fiber, so that the fiber can have the advantages of thin diameter, high tensile breaking strength and anti-creep.

[0034] Preferably, in step (1), the additive I contains a dispersant. The addition of the dispersant can make the ultra-high molecular weight polyethylene raw material fully dissolve in the solvent, promote the complete unfolding of the molecular weight, reduce the spinning viscosity and spinning time, ensure the continuous, rapid and stable spinning, improve the spinning efficiency and the uniformity of the fiber obtained by spinning. In order to further improve the efficiency of spinning, preferably, the amount of the dispersant is 3-20g, specifically 3g, 5g, 10g, 15g or 20g, or any value between these values, and the amount of the solvent I is 200-2000g, specifically 200g, 500g, 1000g, 1500g or 2000g, or any value between these values, relative to 100g of the ultra-high molecular weight polyethylene raw material.

[0035] Preferably, the dispersing agent is selected from at least one of triethylhexylphosphoric acid, sodium dodecyl sulfate, methylamyl alcohol, cellulose derivatives, polyacrylamide, gum ghatti and fatty acid polyglycol esters. Specifically, the cellulose derivatives can be cellulose nitrate and / or carboxymethyl cellulose, and the fatty acid polyglycol esters can be lauric acid ester and / or stearic acid ester. With the above dispersing agents, the dispersion effect of the ultra-high molecular weight polyethylene raw material in the solvent I can be further improved, thereby improving the spinning efficiency and making the prepared fiber more uniform. To further improve the uniformity of the fiber, it is further preferred that the dispersing agent is selected from triethylhexylphosphoric 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. It is further preferred that the solvent I is a mixture of paraffin oil and ethylene glycol, and the mixing volume ratio of paraffin oil to ethylene glycol is 2-9:1.

[0037] Preferably, the step (1) further comprises shearing treatment of the mixed liquid phase. The shearing treatment can make the dissolution of the ultra-high molecular weight polyethylene raw material in the solvent I more complete, promote the complete unfolding of the molecular weight, reduce the spinning viscosity and spinning time, ensure the continuous, rapid and stable spinning, improve the spinning efficiency and improve the uniformity of the spun fiber.

[0038] To further improve the uniformity of the prepared fiber, it is preferred that the shearing treatment comprises at least two shearing processes, and the stirring speed of the latter shearing process is greater than that of the former shearing process. Specifically, when the shearing treatment comprises two shearing processes, the stirring speed of the second shearing process is greater than that of the first shearing process. The stirring speed of the first shearing process can be determined by the test personnel according to the actual test situation. Preferably, to further improve the uniformity of the spun fiber, the stirring speed of the first shearing process is 70-110 rpm, and the difference between the stirring speeds of adjacent two shearing processes is 20-80 rpm.

[0039] More preferably, the shearing treatment comprises three times of shearing; wherein the first shearing is under the condition that the stirring speed is 70-110 rpm, specifically 70 rpm, 80 rpm, 90 rpm, 100 rpm, 110 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 second shearing is under the condition that the stirring speed is 130-170 rpm, specifically 130 rpm, 140 rpm, 150 rpm, 160 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 third shearing is under the condition that 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 fiber prepared under the above conditions has better uniformity.

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

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

[0042] According to the present application, preferably, the antioxidant is at least one selected from tris(2,4-di-tert-butylphenyl) phosphite, pentaerythritol ester, pentaerythritol, diphosphite. The coupling agent is at least one selected from silane coupling agent, titanate coupling agent and aluminate coupling agent. The initiator is 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 breaking strength and creep resistance of the fiber. More preferably, the peroxide organic initiator is at least one selected from benzoyl peroxide, lauryl peroxide, di-tert-butyl peroxide and dicumyl peroxide.

[0043] More preferably, the antioxidant is pentaerythritol and / or diphosphite, the coupling agent is titanate coupling agent and / or silane coupling agent, and the initiator is lauryl 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 can 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 can be at least one selected from calcium carbonate, calcium sulfate and yttrium oxide, the inorganic β crystal nucleating agent can also be a rare earth compound, which can be a compound composed of rare earth elements and other elements, specifically a lanthanide compound and / or a cerium compound, the lanthanide compound can be lanthanum chloride and / or lanthanum carbonate, and the cerium compound can be cerium chloride. The organic β crystal nucleating agent can be at least one selected from phenanthrene, anthracene, 2-mercaptobenzimidazole, triphenol dithiazine, dicarboxylic acid salt, aromatic diamide and TMB-5. The use of the β crystal nucleating agent can induce interface instability between the nucleating agent and the polyethylene phase in the process of further crystallization in hot drawing, generate more crystal nucleation points, increase the number of nucleation, and thus reduce the grain size, increase the fiber hot drawing ratio without breaking, significantly improve the tensile breaking strength and creep resistance of the fiber, and also significantly reduce the diameter of the prepared fiber. To further improve the tensile breaking strength, creep resistance and reduce the diameter of the fiber, it is further preferred that the nucleating agent is calcium carbonate and 2-mercaptobenzimidazole. More preferably, the mass ratio of the calcium carbonate and the 2-mercaptobenzimidazole is 1:0.5-2.

[0045] Preferably, the pre-drawing conditions include at least a drawing ratio of 5-8 times, specifically 5 times, 6 times, 7 times, 8 times, or any value between these values. The fiber prepared under the above conditions has high breaking strength and good creep resistance.

[0046] According to the present application, 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, the screw extruder is a supercharged twin screw extruder. The pressure of the mixture in the supercharged twin screw extruder during the mixing process is maintained at 6-15 MPa, which can further improve the breaking strength and creep resistance of the fiber.

[0047] According to the present application, in step (2), the pre-drawing can be achieved by any kind of machine or structure that can achieve pre-drawing, and preferably, the pre-drawing is achieved by a spinneret and a spinning box.

[0048] According to the present application, preferably, the method further comprises a cooling process for the material obtained after the pre-drawing process; the cooling process can be carried out under any feasible conditions, and as a specific embodiment of the present application, the cooling process is carried out in a cooling water bath. Specifically, the conditions of the cooling process include a temperature of 0-20℃ and a time of 3-10s.

[0049] According to the present application, the solvent II can be at least one of paraffin oil, ethylene glycol and mineral oil, and preferably, the solvent II is paraffin oil.

[0050] Preferably, in step (3), the conditions of the heat drawing include a drawing ratio of 40-60 times, specifically, 40 times, 45 times, 50 times, 55 times, 60 times, or any value between these values, and a temperature of 120-160℃, specifically, 120℃, 130℃, 140℃, 150℃, 160℃, or any value between these values. The fiber prepared under the above conditions of heat drawing has a relatively small diameter, a high tensile breaking strength and a high creep resistance.

[0051] According to the present application, in step (3), the desolventization can be achieved by any feasible way, and preferably, the desolventization is achieved by extraction with an extraction liquid and drying, and the selection of the extraction liquid, the conditions of the extraction and the conditions of the drying can be determined by the person skilled in the art according to the actual situation.

[0052] According to the present application, the amount of the solvent II added can be determined by the person skilled in the art according to the actual situation, and as a specific embodiment of the present application, the amount of the solvent II added is 15-150g relative to 100g of the ultra-high molecular weight polyethylene raw material.

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

[0054] The above-mentioned ultra-high molecular weight polyethylene fiber can ensure the tensile breaking strength of the fiber and the anti-creep performance of the fiber while ensuring the fine diameter, and can be better applied to bulletproof fabric.

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

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

[0057] (1) The ultra-high molecular weight polyethylene powder, the solvent I and the dispersant are stirred together and then added into a dissolving kettle, and a spinning solution is obtained after multi-stage shearing (the first shearing condition includes: stirring speed of 70-110 rpm, time of 30-60 min; the second shearing condition includes: stirring speed of 130-170 rpm, time of 30-60 min; the third shearing condition includes: stirring speed of 180-220 rpm, time of 30-60 min);

[0058] The dispersant is selected from at least one of triethylhexyl phosphate, sodium dodecyl sulfate, methylamyl alcohol, cellulose derivatives, polyacrylamide, gum gur and fatty acid polyethylene glycol ester; and the solvent I is selected from at least two of paraffin oil, ethylene glycol and mineral oil;

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

[0060] (2) The spinning solution enters a pressurized double-screw extruder, and a mixture of an antioxidant, a coupling agent, an initiator, a nucleating agent and paraffin oil is introduced, and spinning is performed, and then the nascent gel fiber is obtained after pre-drawing treatment (draw ratio of 5-8 times) through a spinneret and a spinning box and cooling (temperature of 0-20 °C, time of 3-10 s);

[0061] The antioxidant is selected from at least one of tris (2, 4-di-tert-butylphenyl) phosphite, pentaerythritol ester, pentaerythritol, 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 dicumyl peroxide; and the nucleating agent is a β crystal nucleating agent;

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

[0063] (3) the as-born gel filaments are extracted by the extraction solution to remove the solvent and dried, and then are obtained by multi-stage thermal drawing (draw ratio of 40-60 times, temperature of 120-160°C) to obtain the ultra-high molecular weight polyethylene fibers.

[0064] The ultra-high molecular weight polyethylene fibers prepared by the above method can ensure the tensile breaking strength of the fibers and the creep resistance of the fibers while ensuring the fine diameter.

[0065] The application will be described in detail below by examples. In the following examples, the ultra-high molecular weight polyethylene powder is purchased from Shenzhen Telight New Material Technology Co., Ltd., the molecular weight is 4.5 million (the density is 0.98 g / cm 3 ), the molecular weight is 3 million (the density is 0.97 g / cm 3 ); the aluminum ester coupling agent is purchased from Dongguan Dinghai Chemical Co., Ltd., the product model is DL-411; the pentaerythritol ester is purchased from Shanghai Huijun Chemical Co., Ltd., the product model is PETO; the titanium ester coupling agent is purchased from Dongguan Dinghai Chemical Co., Ltd., the product model is NDZ-201; the silane coupling agent is purchased from Kangjin Chemical Co., Ltd., the product model is 560; the diphosphite is purchased from Liyanlong Chemical Co., Ltd., the product model is RIANOX-686.

[0066] Creep elongation: the parallel fibers with a length of 1.5 m are placed in an environmental chamber for creep performance test by using the suspension weight method, the suspension weight is 20% of the breaking strength of the single fiber, the suspension time is 48 h, and the test temperature is 50°C.

[0067] Breaking tensile strength: the method mentioned in GB / T 14344-2008 is used for test.

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

[0069] Example 1

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

[0071] (2) The spinning solution enters the pressurized twin-screw extruder, the melt pressure in the screw is kept at 6 MPa, and the mixture of antioxidant pentaerythritol ester, initiator benzoyl peroxide, aluminate coupling agent, β crystal nucleating agent calcium carbonate and paraffin oil with a mass ratio of 1:1:1:2:15 is introduced into the mixture of antioxidant pentaerythritol ester, initiator benzoyl peroxide, aluminate coupling agent, β crystal nucleating agent calcium carbonate and paraffin oil with a mass ratio of 1:1:1:2:15 according to the mass ratio of 100:10 (spinning solution: mixture of antioxidant pentaerythritol ester, initiator benzoyl peroxide, aluminate coupling agent, β crystal nucleating agent calcium carbonate and paraffin oil) for spinning treatment, pre-drawing treatment through the spinneret and the spinning box, the pre-drawing ratio is 5 times, and then cooling treatment (temperature is 20℃, time is 10s) is carried out to obtain the primary gel spinning filament;

[0072] (3) After the primary gel spinning filament is extracted by the extraction liquid to remove the solvent and dried, multi-stage hot drawing is carried out, the drawing ratio is 40 times, the drawing temperature is 120℃, and then the ultrahigh molecular weight polyethylene fiber is obtained after the drawing is completed.

[0073] Example 2

[0074] (1) The mixture of dispersant sodium dodecyl sulfate, paraffin oil and mineral oil with a mass ratio of 30:1:69 is stirred together and then added into the dissolving kettle, multi-stage shearing is carried out, the first stage stirring speed is 90 rpm, the second stage stirring speed is 150 rpm, the third stage stirring speed is 200 rpm, and the stirring time of each stage is 60 min, and then the spinning solution is obtained after the stirring is completed; 3

[0075] (2) The spinning solution enters the pressurized twin-screw extruder, the melt pressure in the screw is kept at 15 MPa, and the mixture of antioxidant pentaerythritol, initiator lauroyl peroxide, titanate coupling agent, β crystal nucleating agent 2-mercaptobenzimidazole and paraffin oil with a mass ratio of 1:1:1:5:12 is introduced into the mixture of antioxidant pentaerythritol, initiator lauroyl peroxide, titanate coupling agent, β crystal nucleating agent 2-mercaptobenzimidazole and paraffin oil with a mass ratio of 1:1:1:5:12 according to the mass ratio of 100:10 (spinning solution: mixture of antioxidant pentaerythritol, initiator lauroyl peroxide, titanate coupling agent, β crystal nucleating agent 2-mercaptobenzimidazole and paraffin oil) for spinning treatment, pre-drawing treatment through the spinneret and the spinning box, the pre-drawing ratio is 8 times, and then cooling treatment (temperature is 15℃, time is 8s) is carried out to obtain the primary gel spinning filament;

[0076] (3) After the primary gel spinning filament is extracted by the extraction liquid to remove the solvent and dried, multi-stage hot drawing is carried out, the drawing ratio is 60 times, the drawing temperature is 160℃, and then the ultrahigh molecular weight polyethylene fiber is obtained after the drawing is completed.

[0077] Example 3

[0078] (1) The mixture of dispersant sodium dodecyl sulfate, paraffin oil and mineral oil with a mass ratio of 30:1:69 is stirred together and then added into the dissolving kettle, multi-stage shearing is carried out, the first stage stirring speed is 90 rpm, the second stage stirring speed is 150 rpm, the third stage stirring speed is 200 rpm, and the stirring time of each stage is 60 min, and then the spinning solution is obtained after the stirring is completed; 3 ​), dispersant polyacrylamide, mixed solvent of paraffin oil ethylene glycol and mineral oil with mass ratio of 30:1:69 were stirred together and then added into the dissolving kettle, and then multi-stage shearing was carried out, the stirring speed of the first stage was 110 rpm, the stirring speed of the second stage was 170 rpm, the stirring speed of the third stage was 220 rpm, and the stirring time of each stage was 45 min, and then the spinning solution was obtained after the stirring was completed;

[0079] (2) The spinning solution entered the pressurized double screw extruder, the melt pressure in the screw was maintained at 10 MPa, pre-drawing treatment was carried out through the spinneret and the spinning beam, the pre-drawing ratio was 7 times, and then the mixed solution of antioxidant diphosphite, initiator di-tert-butyl peroxide, silane coupling agent and β crystal nucleating agent TMB-5 with mass ratio of 100:10 (spinning solution: mixed solution of antioxidant diphosphite, initiator di-tert-butyl peroxide, silane coupling agent and β crystal nucleating agent TMB-5) was introduced into the mixed solution of antioxidant diphosphite, initiator di-tert-butyl peroxide, silane coupling agent and β crystal nucleating agent TMB-5 with mass ratio of 1:1:1:4:13, and then spinning treatment was carried out, and then primary gel fiber was obtained after cooling treatment (temperature was 0 ℃, and time was 3 s).

[0080] (3) After the primary gel fiber was treated by extraction solution to remove the solvent and drying treatment, multi-stage heat drawing was carried out, the drawing ratio was 50 times, and the drawing temperature was 140 ℃, and then the ultra-high molecular weight polyethylene fiber was obtained after the drawing was completed.

[0081] Example 4

[0082] The ultra-high molecular weight polyethylene fiber was 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] The ultra-high molecular weight polyethylene fiber was prepared according to the method of Example 1, except that the antioxidant pentaerythritol ester was not added in step (2).

[0085] Example 6

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

[0087] Example 7

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

[0089] Example 8

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

[0091] Example 9

[0092] The ultra-high molecular weight polyethylene fiber was 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 with a mass ratio of 1:1.

[0093] Example 10

[0094] The ultra-high molecular weight polyethylene fiber was 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 with a mass ratio of 1:0.5.

[0095] Example 11

[0096] The ultra-high molecular weight polyethylene fiber was 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 with a mass ratio of 1:2.

[0097] Example 12

[0098] The ultra-high molecular weight polyethylene fiber was 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 with a mass ratio of 1:0.1.

[0099] Example 13

[0100] The ultra-high molecular weight polyethylene fiber was 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 with a mass ratio of 1:3.

[0101] Comparative Example 1

[0102] The ultra-high molecular weight polyethylene fiber was 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] The ultra-high molecular weight polyethylene fiber was prepared according to the method of Example 1, except that no aluminum stearate coupling agent and nucleating agent calcium carbonate were added in step (2).

[0105] Comparative Example 3

[0106] Ultra-high molecular weight polyethylene fibers were 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 fibers were prepared according to the method of Example 1, except that the initiator benzoyl peroxide was not added in step (2).

[0109] like Figure 1 As shown in the figure, the crystal morphology of ultra-high molecular weight polyethylene prepared in Example 1 and Comparative Example 1 is obtained by polarizing light microscopy (polarizing microscope purchased from Shanghai Wumo Optical Instrument Co., Ltd., model WMP-6880). As can be seen from the figure, the crystal size of UHMWPE after adding nucleating agent is smaller and the number of crystals increases. In the further crystallization process of hot stretching, it can induce the interface instability between nucleating agent and polyethylene phase, generate more crystal nuclei, increase the number of nuclei, thereby reducing the crystal size, increasing the fiber hot stretching ratio without breakage, effectively reducing the fiber diameter, and improving the tensile breaking strength of the fiber.

[0110] like Figure 2 As shown, the surface of the fiber obtained in Example 1 became rougher, indicating that the fiber underwent a chemical reaction that led to a change in surface morphology.

[0111] like Figure 3 As shown, the fiber prepared in Example 1 exhibits excellent creep resistance under higher temperature conditions, indicating that the intermolecular forces are 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 Results of Ultra-High Molecular Weight Polyethylene Fibers Prepared in the Examples and Comparative Examples

[0114]

[0115]

[0116] As shown in Table 1, the UHMWPE fibers prepared after crystallization regulation and chemical crosslinking have ultra-low fineness, ranging from 5.5D to 30D, with tensile breaking strength exceeding 350 N / tex and creep elongation below 3%. In contrast, the unmodified UHMWPE fibers (Comparative Example 2) have lower strength and poor creep resistance. The data from the comparative examples and the above comparative examples demonstrate that the simultaneous introduction of nucleating agents, coupling agents, and initiators can yield ultra-fine denier UHMWPE fiber materials with low creep and high tensile breaking strength.

[0117] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that each technical feature is combined in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. An ultra-high molecular weight polyethylene fiber, characterized by, The fiber has a fineness less than or equal to 30D, the fiber has a tensile breaking strength greater than or equal to 350N / tex, and the fiber has a creep elongation less than or equal to 3% at 50℃; The fiber contains a nucleating agent, the nucleating agent is a β crystal nucleating agent, 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, triphenoldithiazine, dicarboxylic acid salt, aromatic diamide and TMB-5; The preparation method of the ultra-high molecular weight polyethylene fiber comprises the following steps: (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, an additive II, a nucleating agent and a solvent II, and then performing spinning and pre-drawing to obtain a primary frozen gel yarn; The additive II contains a coupling agent and an initiator; (3) removing the solvent from the primary frozen gel yarn, and then performing heat drawing treatment.

2. The ultra-high molecular weight polyethylene fiber according to claim 1, characterized by The fiber has a tensile breaking strength of 350-500N / tex, and a fineness less than or equal to 10D.

3. The ultra-high molecular weight polyethylene fiber according to claim 2, characterized by The fiber has a tensile breaking strength of 370-400N / tex, and a creep elongation less than or equal to 2.1% at 50℃.

4. The ultra-high molecular weight polyethylene fiber according to any one of claims 1 to 3, characterized in that, The content of the nucleating agent in the fiber is 1-11% by mass.

5. A method for producing an ultrahigh molecular weight polyethylene fiber, characterized by, Comprises the following steps: (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, an additive II, a nucleating agent and a solvent II, and then performing spinning and pre-drawing to obtain a primary frozen gel yarn; The additive II contains a coupling agent and an initiator, the nucleating agent is a β crystal nucleating agent, 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, triphenoldithiazine, dicarboxylic acid salt, aromatic diamide and TMB-5; (3) removing the solvent from the primary frozen gel yarn, and then performing heat drawing treatment.

6. The production method according to claim 5, wherein In step (1), the additive I contains a dispersant; The amount of the dispersant is 3-20g, and the amount of the solvent I is 200-2000g, relative to 100g of the ultra-high molecular weight polyethylene raw material.

7. The production method according to claim 6, wherein The dispersant is selected from at least one of triethylhexyl phosphoric acid, sodium dodecyl sulfate, methylamyl alcohol, cellulose derivatives, polyacrylamide, gum and fatty acid polyethylene glycol ester; The solvent I is selected from at least two of paraffin oil, ethylene glycol and mineral oil.

8. The preparation method according to claim 5, characterized in that, Step (1) further comprises: performing shear treatment on the mixed solution; The shear treatment comprises at least two shears, and the stirring speed of the later shear is greater than that of the previous shear.

9. The production method according to claim 8, characterized by, The shear treatment comprises three shears; wherein, The first shear at least comprises: a stirring speed of 70-110 revolutions per minute and a time of 30-60 minutes; The second shearing condition at least comprises: stirring speed of 130-170 rpm, time of 30-60 min; The third shearing condition at least comprises: stirring speed of 180-220 rpm, time of 30-60 min.

10. The production method according to any one of claims 5 to 9, characterized by, In step (2), 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, relative to 100 g of the ultra-high molecular weight polyethylene raw material.

11. The method of claim 10, wherein, The auxiliary II further comprises an antioxidant; The amount of the antioxidant is 1.5-10 g, relative to 100 g of the ultra-high molecular weight polyethylene raw material. The antioxidant is selected from at least one of tris (2, 4-di-tert-butylphenyl) phosphite, pentaerythritol ester, pentaerythritol, 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, lauryl peroxide, di-tert-butyl peroxide and dicumyl peroxide.

12. The method of making according to any one of claims 5-9, wherein, In step (2), the nucleating agent is calcium carbonate and 2-mercapto benzimidazole.

13. The method of claim 12, wherein, The mass ratio of the calcium carbonate to the 2-mercapto benzimidazole is 1:0.5-2.

14. The method of any one of claims 5-9, wherein, In step (2), the pre-drawing condition at least comprises: drawing ratio of 5-8 times; The method further comprises cooling treatment on the material obtained after the pre-drawing treatment; In step (3), the hot-drawing condition at least comprises: drawing ratio of 40-60 times, temperature of 120-160 ℃.

15. The ultra-high molecular weight polyethylene fiber of any one of claims 1-4 or the ultra-high molecular weight polyethylene fiber prepared by the preparation method of any one of claims 5-14 is applied to a bulletproof fabric.

16. The use according to claim 15, characterized in that, The bulletproof fabric is a bulletproof vest.

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