Disclosure of Invention
Technical problem to be solved
In view of the above, the present inventors have desired to provide an ultra-high molecular weight polyethylene fiber and a method for preparing the same, which overcome the problems of the prior art. The ultra-high molecular weight polyethylene fiber can be woven into cutting-proof gloves or cutting-proof protective clothing and the like, high-strength protective performance and better wearing comfort are realized, the dyeing property of zero number is easy, meanwhile, abrasion and damage to production equipment can be avoided, the production cost is saved, and the performance timeliness of the cutting-proof gloves or the cutting-proof protective clothing is prolonged.
(II) technical scheme
In order to achieve the purpose, the invention adopts the main technical scheme that:
in one aspect of the application, an ultra-high molecular weight polyethylene fiber is provided, which comprises an ultra-high molecular weight polyethylene matrix and boron nitride micron-sized short fibers dispersed in the matrix, wherein the content of the boron nitride micron-sized short fibers is 0.25-20 wt%
Typically, but not limited to, the boron nitride micro-sized staple fibers are present in the ultra high molecular weight polyethylene-containing matrix in an amount of 0.25 wt%, 0.5 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0 wt%, 7.5 wt%, 8.0 wt%, 8.5 wt%, 9.0 wt%, 9.5 wt%, 10.0 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt%, or 20 wt%. Tests show that: generally, when the content of the boron nitride micron-sized short fibers is more than 7%, the cutting grade is more than 5; among them, 8-11% of the cut resistance can be very good, and 4-5.5% is on the cut-proof level 4. However, the higher the content of the boron nitride micron-sized short fibers is, the greater the production difficulty is, the poorer the spinnability of the prepared polyethylene fiber yarns is, and therefore, the preferred content of the boron nitride micron-sized short fibers is 5-12 wt%.
If the content of the boron nitride micron-sized short fibers is too high, the specific gravity of the polyethylene matrix is too low, the spinnability of the prepared ultra-high molecular weight polyethylene fibers is poor (the fibers are easy to break in the spinning process), and if the content of the boron nitride micron-sized short fibers is too low, the purpose of increasing the cutting resistance cannot be achieved.
The commonly prepared boron nitride is of a graphite type structure, commonly called white graphite, and the natural color of the boron nitride is white, so that the dyeing property of the ultrahigh molecular weight polyethylene fiber is not influenced. The cubic boron nitride is a novel high-temperature-resistant superhard material used for manufacturing drill bits, grinding tools and cutting tools, and can be converted into diamond-type boron nitride under the conditions of high temperature (1800 ℃) and high pressure (800Mpa), similar to the principle that graphite is converted into diamond. The boron nitride used in the invention mainly refers to stereo boron nitride, and some graphite type boron nitride (such as mass ratio of 6-8: 4-2) can be doped. The boron nitride has certain self-lubricating property, the friction coefficient of the hexagonal boron nitride is as low as 0.16, and the hexagonal boron nitride can be used as a lubricant in some occasions. Due to the self-lubricating property, the friction loss effect on preparation equipment can be reduced, and the service life of the equipment is prolonged.
The diameter of the boron nitride micron-sized short fiber is preferably 0.1-20 μm, and more preferably 5-12 μm; the length of the boron nitride micron-sized short fibers is preferably 1 to 180 μm, more preferably 50 to 100 μm; and the shape of the boron nitride micron-sized short fiber is long rod-shaped particles with the length larger than the diameter. Compared with powdery boron nitride, the fibrous boron nitride has better anti-cutting performance for the prepared ultra-high molecular weight polyethylene fiber. The inorganic micro powder mainly plays a role of a physical cross-linking point in the fiber, and the improvement of the cutting resistance of the fiber is realized by limiting the slippage between macromolecular chains of the polyethylene fiber, but the inorganic micro powder is more prone to be squeezed to one side by a blade edge instead of resisting the damage of the blade edge in the fiber cutting process of the blade, so the improvement degree of the cutting resistance is limited. The fibrous boron nitride has no problem of being squeezed to one side by a blade, and can play a better role in cutting resistance.
However, the boron nitride micron-sized short fibers are inorganic fillers, the affinity with the polyethylene matrix is poor, good dispersion cannot be formed when the pure boron nitride micron-sized short fibers are added into the polyethylene matrix, the dispersion uniformity and firmness of the boron nitride micron-sized short fibers in the matrix have great influence on the properties of finally prepared polyethylene fiber yarns, and the boron nitride micron-sized short fibers have poor binding force with ultra-high molecular weight polyethylene fibers under the condition of poor affinity, are easy to fall off or pull out in the spinning and stretching processes and influence the cutting resistance.
Therefore, further, in order to improve the affinity and dispersibility between the boron nitride micron-sized short fibers and the polyethylene matrix, the invention adopts one or more of the following modes:
the method I comprises the following steps: modifying the boron nitride micron-sized short fibers by using a coupling agent;
the second method comprises the following steps: coating modification, namely coating a high molecular polymer on the surface of the boron nitride micron-sized short fiber;
the third method comprises the following steps: mixing the boron nitride micron-sized short fibers and boron nitride particles for use, wherein the crossed positions or gaps of the short fibers are supplemented by the boron nitride particles;
the method is as follows: the EVA (ethylene-vinyl acetate copolymer) is doped into the ultra-high molecular weight polyethylene, and the dispersibility of the boron nitride micron-sized short fibers in the matrix material can be obviously improved by doping the EVA;
the fifth mode is as follows: a plurality of tiny micropores (mostly nano micropores) can be formed on the surface of the short fiber, so that on one hand, the specific surface area of the boron nitride micron-sized short fiber can be increased, and the bonding tightness between the boron nitride micron-sized short fiber and the ultrahigh molecular weight polyethylene is improved; on the other hand, compared with the boron nitride micron-sized short fiber without micropores, the boron nitride micron-sized short fiber has better flexibility which is comparable with that of carbon fiber, and is beneficial to improving the spinnability of the finally prepared anti-cutting ultrahigh molecular weight polyethylene fiber and the softness, the fitting property and the wearability of a woven glove; the boron nitride fiber with better flexibility is not easy to puncture the polyethylene substrate along with the repeated bending use of the polyethylene fiber wire to cause the pulling-out of the polyethylene substrate, and has less damage to equipment.
The specific method of the first mode can be as follows: dissolving the boron nitride micron-sized short fibers in 1-5mol/L sodium hydroxide solution, stirring for 10-20h at 110-120 ℃, performing suction filtration, washing with deionized water, and drying to obtain activated boron nitride micron-sized short fibers with hydroxylated surfaces; preparing acetone and dilute hydrochloric acid with the pH value of 2-4 into a solution according to the volume ratio of 6-10:1, adding a coupling agent into the solution, hydrolyzing at 40-60 ℃ for 0.5-1h, adding activated boron nitride micron-sized short fibers into the solution, continuously stirring for 2-5h, and drying to obtain the modified boron nitride micron-sized short fibers. Wherein the coupling agent is KH570 or CAI, and the coupling agent accounts for 1-10% of the raw material of the boron nitride micron-sized short fiber.
The specific method of the second mode can be as follows: heating the boron nitride micron-sized short fiber raw material to 250-350 ℃, adding mixed resin and stirring to form a mixture, adding a dispersing agent and stirring before the mixture starts to agglomerate, and adding a curing agent and an accelerant and stirring; cooling the materials to 40-90 ℃, transferring the materials to a crusher for crushing, and finally sieving the materials for 200 meshes and 1000 meshes to obtain the modified boron nitride micron-sized short fibers coated with the high molecular polymer; the dispersing agent is one or more of polyethylene wax, stearic acid amide, ethylene bis-stearamide, calcium stearate, zinc stearate, liquid paraffin and silicone oil; the accelerant is mica powder, DDM, DMP-30, CaO and TiO 2 One or more of; the curing agent is one or more of imidazole, acid anhydride, Lewis acid, hexamethylenetetramine and ethyl orthosilicate compounds; the high molecular polymer can be phenolic resin, polyurethane resin, EVA and the like. Wherein the dosage of the dispersant is 0.02-0.05% of the mass of the boron nitride micron-sized short fiber raw material; the dosage of the curing agent is 0.1-0.5% of the mass of the boron nitride micron-sized short fiber raw material; the promotionThe dosage of the agent is 0.1-1% of the mass of the boron nitride micron-sized short fiber raw material.
The third method can be as follows: the median particle size of the boron nitride particles is 0.1-12 mu m, and the mass ratio of the boron nitride micron-sized short fibers to the boron nitride particles is 5-20: 1. Before mixing with the ultra-high molecular weight polyethylene master batch, the boron nitride micron-sized short fibers and the boron nitride particles can be premixed in a dry state, the boron nitride particles are adsorbed on the surfaces of the boron nitride micron-sized short fibers, the surface roughness of the boron nitride micron-sized short fibers is effectively improved, the surface potential is increased, the bonding force with the interface of the ultra-high molecular weight polyethylene fibers is enhanced, and the cutting resistance of the fibers is improved. The method has the advantages that boron nitride particles are introduced on the basis of the boron nitride micron-sized short fibers, so that the effect of obvious reinforcement and toughening is achieved, firstly, in the stretching process of the ultra-high molecular weight polyethylene fibers, the boron nitride particles generate a stress concentration effect to excite surrounding matrixes to generate silver lines, and meanwhile, the matrixes among the particles generate yield to absorb certain deformation work, so that the toughening effect is achieved; secondly, the existence of the boron nitride particles can resist and passivate the crack propagation of the ultra-high molecular weight polyethylene fiber matrix, play a role of a physical cross-linking point and show fiber reinforcement; thirdly, the existence of the micro-nano particles can obviously reduce the average size of the crystal grains of the ultra-high molecular weight polyethylene fiber, thereby being beneficial to improving the modulus. The ultra-high molecular weight polyethylene fiber finally shows enhanced mechanical property, and can improve the cutting resistance.
The fourth way can be: the boron nitride is more inclined to be dispersed in the EVA, and the EVA has good affinity with the ultra-high molecular weight polyethylene and can be well mixed and mutually dissolved, so that the dispersibility of the boron nitride micron-sized short fibers in the ultra-high molecular weight polyethylene fibers can be enhanced by adding a certain proportion of the EVA. Preferably, the mass ratio of the EVA to the ultra-high molecular weight polyethylene is 1:20-30, and the EVA becomes a solid dispersant of the boron nitride.
The fifth implementation may be: using boric acid and melamine as raw materials, carrying out hydrothermal synthesis on melamine diboric acid precursor powder, then adopting a freeze-drying method to rapidly cool a hot water solution of the melamine diboric acid precursor by using liquid nitrogen, and then drying to synthesize melamine diboric acid fibers; then thermally cracking at high temperature under a protective atmosphereThe melamine diboronic acid fiber is used to obtain the porous boron nitride fiber. Or taking nitrogen compound, boron compound and pore-forming agent as raw materials, dissolving and mixing the raw materials by water, heating the raw materials in water bath under violent stirring to form a mixture of boride and nitride, dehydrating and drying the mixture to obtain a boron nitride fiber precursor, then loading the precursor into a corundum fire boat, putting the corundum fire boat into a vacuum tube furnace, carrying out pyrolysis at a certain temperature for a certain time in a flowing nitrogen atmosphere, heating and carrying out heat treatment on the pyrolysis product in a muffle furnace at a certain temperature for a certain time to remove possible free carbon and the like, thus obtaining the boron nitride fiber with micropores, wherein the specific surface of the prepared porous boron nitride fiber can reach 450m 2 g -1 The above.
Preferably, the first mode and the fourth mode can be jointly adopted, or the first mode and the third mode can be jointly adopted; the second mode can be used alone, and the fourth mode can be used alone. The combined use of the third mode and the fourth mode can also have good effect, and the process is simpler, the production cost is higher, and the process period is shorter.
Based on the above, the invention also relates to a preparation method of the ultra-high molecular weight polyethylene fiber, which comprises the following steps:
s1, mixing the boron nitride micron-sized short fibers with ultra-high molecular weight polyethylene powder with the molecular weight of 20-600 ten thousand, and then heating and swelling the mixture in a spinning solvent to obtain a mixed material; or:
dispersing boron nitride in a spinning solvent in advance, adding a surfactant, mixing to prepare an emulsified material, then dispersing ultra-high molecular weight polyethylene powder with the molecular weight of 20-600 ten thousand in the spinning solvent, stirring, adding the emulsified material, stirring again, heating and swelling to obtain a mixed material;
s2, blending and extruding the mixture through an extruder, cooling and forming through a coagulating bath to obtain nascent fibers, and extracting, drying and thermally drawing the nascent fibers at multiple stages to obtain ultrahigh molecular weight polyethylene fibers; wherein the content of the boron nitride micron-sized short fibers is 0.25-20 wt%.
According to the preparation method, the diameter of the boron nitride micron-sized short fiber is 0.1-20 μm, the length of the boron nitride micron-sized short fiber is 1-180 μm, and the shape of the boron nitride micron-sized short fiber is long rod-shaped particles with the length larger than the diameter. More preferably, the boron nitride micro-sized short fibers preferably have a diameter of 5 to 12 μm and a length of 50 to 100 μm. For example, the boron nitride micro-sized staple fibers may have diameters of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm; the length can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm.
According to the preparation method of the invention, in step S1, the boron nitride micron-sized short fibers and boron nitride particles are dry-mixed in advance and then mixed with ultra-high molecular weight polyethylene powder; the boron nitride particles are boron nitride particles with the median particle size of 0.1-12 mu m, and the mass ratio of the boron nitride micron-sized short fibers to the boron nitride particles is 5-20: 1.
According to the preparation method, the boron nitride micron-sized short fiber is a modified boron nitride micron-sized short fiber with the surface coated with a high molecular polymer, or is activated by hydroxyl and then connected with a coupling agent; or the boron nitride micron-sized short fiber is a boron nitride short fiber with micropores formed on the surface in the preparation process.
According to the preparation method, the boron nitride micron-sized short fiber is a modified boron nitride micron-sized short fiber with the surface coated with a high molecular polymer, and the modification method comprises the following steps:
heating the boron nitride micron-sized short fiber raw material to 250-350 ℃, adding mixed resin and stirring to form a mixture, adding a dispersing agent and stirring before the mixture starts to agglomerate, and adding a curing agent and an accelerant and stirring; cooling the materials to 40-90 ℃, transferring the materials to a crusher for crushing, and finally sieving the materials for 200 meshes and 1000 meshes to obtain the modified boron nitride micron-sized short fibers coated with the high molecular polymer; the dispersing agent is one or more of polyethylene wax, stearic acid amide, ethylene bis-stearamide, calcium stearate, zinc stearate, liquid paraffin and silicone oil; the accelerant is mica powder, DDM, DMP-30, CaO and TiO 2 One or more of; the curing agent is imidazole, anhydride or LewisOne or more of acid, hexamethylenetetramine and ethyl orthosilicate compound;
or the boron nitride micron-sized short fiber is modified boron nitride micron-sized short fiber which is activated by hydroxyl and then connected with a coupling agent, and the specific method comprises the following steps:
dissolving boron nitride micron-sized short fibers in 1-5mol/L sodium hydroxide solution, stirring for 10-20h at 110-120 ℃, performing suction filtration, washing with deionized water, and drying to obtain activated boron nitride micron-sized short fibers with hydroxylated surfaces; preparing acetone and dilute hydrochloric acid with the pH value of 2-4 into a solution according to the volume ratio of 6-10:1, adding a coupling agent into the solution, hydrolyzing at 40-60 ℃ for 0.5-1h, adding activated boron nitride micron-sized short fibers into the solution, continuously stirring for 2-5h, and drying to obtain the modified boron nitride micron-sized short fibers.
According to the preparation method, the dosage of the dispersant is 0.02-0.05% of the mass of the boron nitride micron-sized short fiber raw material; the dosage of the curing agent is 0.1-0.5% of the mass of the boron nitride micron-sized short fiber raw material; the dosage of the accelerator is 0.1-1% of the mass of the boron nitride micron short fiber raw material.
According to the preparation method, the coupling agent is KH570 or CAI, and the coupling agent accounts for 1-10% of the raw material of the boron nitride micron-sized short fiber.
According to the preparation method of the invention, in the step S1, EVA powder is further included, and the ratio of the EVA powder to the ultra-high molecular weight polyethylene powder is 1: 20-30.
Typically, but not by way of limitation, the ultra-high molecular weight polyethylene has a molecular weight of 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 420, 440, 460, 480, 500, 520, 540, 560, 580 or 600 ten thousand.
In a preferred embodiment of the present invention, the particles of the boron nitride micro-sized short fibers have a diameter of 0.1 to 20 μm and a length of 1 to 180 μm. Further, the shape of the particles of the boron nitride micron-sized short fibers is long rod-shaped particles with the length larger than the diameter; more preferably 20-60 μm in length. Typically, but not by way of limitation, the boron nitride micro-sized staple fibers have a particle length of 20-30 μm, 30-40 μm, 40-50 μm, 50-60 μm, 60-80 μm, or 80-100 μm.
Preferably, the spinning solvent is one or more selected from white oil, mineral oil, vegetable oil, paraffin oil and decalin.
In a preferred embodiment of the present invention, the molecular weight of the ultra-high molecular weight polyethylene is 200-500 ten thousand. The larger the molecular weight of the ultra-high molecular weight polyethylene is, the better the anti-cutting effect is, but the larger the preparation difficulty is, the spinnability of the polyethylene fiber yarn and the wearability after the polyethylene fiber yarn is prepared into the glove can be influenced.
The higher the molecular weight of the ultra-high molecular weight polyethylene is, the higher the cutting resistance and the mechanical strength are, but if the molecular weight is too large, the viscosity is too large, the difficulty is high when extruding and manufacturing the fiber yarn, the fiber yarn is not easy to form, the requirement on equipment is high in the preparation process, and the equipment loss is large. Through repeated tests, the performance of the ultra-high molecular weight polyethylene fiber yarn obtained when the molecular weight is 200-500 ten thousand is optimal in all aspects, and the loss to equipment is low.
In a preferred embodiment of the present invention, the extruder is a twin-screw extruder, and the temperature of each zone of the twin-screw extruder is controlled between 100 ℃ and 300 ℃.
The present invention relates to an ultra-high-molecular-weight polyethylene fiber produced by the production method described in any one of the above examples.
The invention also relates to a cutting-proof glove or a cutting-proof clothes, which comprises a braided fabric formed by braiding the ultra-high molecular weight polyethylene fiber prepared in any one of the embodiments or the preparation methods.
(III) advantageous effects
The invention has the beneficial effects that:
(1) according to the invention, the boron nitride micron-sized short fibers are used as reinforcing materials and dispersed in the ultrahigh molecular weight polyethylene fiber matrix material, so that the ultrahigh molecular weight polyethylene fiber with the cutting resistance is obtained. Compared with the method for blending and weaving the glass fiber, the steel wire and other materials with the ultra-high molecular weight polyethylene fiber in the prior art, the glove or the glove blank woven by the ultra-high molecular weight polyethylene fiber with the ultra-high cutting resistance has better wearing comfort, such as softness, better touch feeling, no burr, pruritus, poking and scratching and the like, is easy to wear and the like.
(2) Compared with a carbon fiber material (with black primary color) as a reinforcing additive, the boron nitride micron-sized short fiber used in the invention is white, so that the prepared ultra-high molecular weight polyethylene fiber can be dyed as required in the later period, and the polyethylene fiber or fabrics such as gloves woven in the later period can be dyed as required.
(3) The invention uses the boron nitride micron-sized short fiber instead of the boron nitride particle powder, thereby having better cutting resistance.
(4) The boron nitride has self-lubricating property, so that the wear to equipment is small in the production process, the equipment and production cost is reduced, and the production efficiency is not negatively influenced.
(5) The affinity and the dispersibility of the boron nitride micron-sized short fibers and the ultrahigh molecular weight polyethylene fiber matrix are further improved in various modes, the holding force of the polyethylene fiber matrix on the boron nitride micron-sized short fibers is improved, the boron nitride micron-sized short fibers are not easy to shift/separate from the surface of the matrix, and therefore the boron nitride micron-sized short fibers can be kept in the ultrahigh molecular weight polyethylene fiber matrix more durably, and the cutting resistance, the aging resistance and the like of finally prepared polyethylene fibers are improved.
In conclusion, the cutting resistance of the ultra-high molecular weight polyethylene fiber is greatly improved, and the cutting resistance grade of woven fabrics such as gloves can stably reach the 5-grade of European standard 388-2003. The ultrahigh-cutting-resistant ultrahigh-molecular-weight polyethylene fiber produced according to the invention does not need to be blended and reinforced with materials such as steel wires and glass fibers, and the produced protective gloves are soft in texture, light, handy and sensitive, are not easy to fatigue after being worn for a long time, realize the consideration of ultrahigh cutting-resistant and wearing comfort, are easy to dye, and have good protection effect on equipment.
Detailed Description
For better understanding of the present invention, the present invention is described in detail by the following specific examples.
Example 1
The embodiment provides a preparation method of an ultrahigh molecular weight polyethylene fiber, which comprises the following steps:
(1) 1200g of boron nitride micron-sized short fibers with the length of 10-20 microns are taken and dispersed in 5Kg of white oil, 300g of linear alkyl benzene sodium sulfonate (LAS) serving as a surfactant is added, and the mixture is uniformly stirred at a high speed and emulsified to obtain an emulsified material.
(2) And (2) putting the emulsified material and 15Kg of ultra-high molecular weight polyethylene powder with the molecular weight of 200 ten thousand and the average particle size of 100 mu m into 95Kg of white oil, stirring and mixing at a high speed for 0.5h, heating to 70 ℃, preserving heat for 2h, stirring and mixing for 0.5h, and repeating until complete swelling to obtain a mixture.
(3) And (2) blending and extruding the mixture by a double-screw extruder, cooling and forming by a coagulating bath to obtain nascent fibers, extracting, drying and carrying out multi-stage hot drawing on the obtained nascent fibers to prepare white ultrahigh molecular weight polyethylene ultrahigh cutting-resistant fibers, wherein the dispersion concentration of the boron nitride micron-sized short fibers in the ultrahigh molecular weight polyethylene is 7.4%. Wherein, the temperature of each area of the double screw is controlled to be 180-260 ℃, and the drawing ratio is 15.
The fiber has good dyeability, no prickling feeling and comfortable wearing, and the cut-resistant grade is 5 grade by EN388-2003 test.
Example 2
The embodiment provides a preparation method of an ultrahigh molecular weight polyethylene fiber, which comprises the following steps:
(1) 1200g of boron nitride micron-sized short fiber with a plurality of micropores on the surface, the length of which is 20-40 mu m, is taken and dispersed in 5Kg of white oil, 300g of linear alkyl benzene sulfonic acid (LAS) which is a surfactant is added, and the mixture is stirred uniformly at a high speed for emulsification to obtain an emulsified material.
(2) And (2) putting the emulsified material and 15Kg of ultra-high molecular weight polyethylene powder with the molecular weight of 200 ten thousand and the average particle size of 100 mu m into 95Kg of white oil, stirring and mixing at a high speed for 0.5h, heating to 70 ℃, preserving heat for 2h, stirring and mixing for 0.5h, and repeating until complete swelling to obtain a mixture.
(3) And (2) blending and extruding the mixture by a double-screw extruder, cooling and forming by a coagulating bath to obtain nascent fibers, extracting, drying and carrying out multistage hot drawing on the nascent fibers to obtain white ultrahigh molecular weight polyethylene ultrahigh cutting-resistant fibers, wherein the dispersion concentration of the boron nitride micron-sized short fibers in the ultrahigh molecular weight polyethylene is 7.4%. Wherein the temperature of each zone of the double screw is controlled at 180-260 ℃, and the stretching ratio is 15.
The fiber has the advantages of good dyeability, soft hand feeling, no prickling feeling and comfortable wearing, and the cut-resistant grade is 5 grade according to the EN388-2003 test.
Example 3
The embodiment provides a preparation method of an ultrahigh molecular weight polyethylene fiber, which comprises the following steps:
(1) and (2) dissolving 1000g of boron nitride micron-sized short fibers with the length of 20-30 microns in 1L of 5mol/L sodium hydroxide solution, stirring for 12 hours at 120 ℃, washing for 3 times by using deionized water after suction filtration, and drying at 60 ℃ to obtain the surface hydroxylated boron nitride micron-sized short fibers.
(2) Preparing acetone and dilute hydrochloric acid with the pH value of 3 into a solution according to the volume ratio of 9:1, adding 50g of a coupling agent KH570, hydrolyzing at 60 ℃ for 1h, then adding the surface hydroxylated boron nitride micron-sized short fiber obtained in the step (1) into the solution, mixing with the hydrolyzed coupling agent, stirring at 50 ℃ for 3h, carrying out suction filtration, washing with deionized water for 3 times, and drying to obtain the surface coupling agent modified boron nitride micron-sized short fiber.
(3) And (2) performing ball milling dry mixing on the surface coupling agent modified boron nitride micron-sized short fibers and 20Kg of ultra-high molecular weight polyethylene powder with the molecular weight of 300 ten thousand and the average particle size of 100 mu m for 20min, putting the mixture into 100Kg of white oil, stirring and mixing for 2h, heating to 65 ℃, stirring and mixing for 2h until the mixture is completely swelled, and thus obtaining a mixture.
(4) And (2) blending and extruding the mixed mixture by a double-screw extruder, cooling and forming by a coagulating bath to obtain nascent fibers, extracting, drying and carrying out multi-stage hot drawing on the nascent fibers to obtain white ultrahigh molecular weight polyethylene ultrahigh cutting-resistant fibers, wherein the dispersion concentration of the boron nitride fibers in the ultrahigh molecular weight polyethylene is 4.76%. Wherein the temperature of each area of the twin-screw is controlled at 170-220 ℃, and the drawing ratio is 20.
The fiber has good dyeability, no prickling feeling and comfortable wearing, and the anti-cutting grade is 4 grade according to the EN388-2003 test.
Example 4
The embodiment provides a preparation method of an ultrahigh molecular weight polyethylene fiber, which comprises the following steps:
(1) 1600g of boron nitride micron-sized short fibers with the length of 30-60um and 200g of boron nitride powder with the median particle size of 10um are taken to be dry-mixed in a ball mill for 20min in advance to obtain dry-mixed material of the boron nitride fibers and the boron nitride powder.
(2) And mechanically mixing the dry mixture and 20kg of ultra-high molecular weight polyethylene powder with the molecular weight of 260 ten thousand and the average particle size of 100um for 20min, adding the mixture into 100kg of white oil, heating to 65 ℃, stirring and mixing for 2h until the mixture is completely swelled to obtain the mixture.
(3) And (2) blending and extruding the mixed mixture by a double-screw extruder, cooling and forming by a coagulating bath to obtain nascent fiber, extracting, drying and carrying out multi-stage hot drawing on the obtained nascent fiber to prepare white ultrahigh molecular weight polyethylene ultrahigh cutting-resistant fiber, wherein the dispersion concentration of boron nitride in the ultrahigh molecular weight polyethylene is 8.26%. Wherein the temperature of each zone of the double screw is controlled at 220 ℃ of 180 ℃, and the stretching ratio is 8.
The fiber has good dyeability, no prickling feeling and comfortable wearing, and the cut-resistant grade is 5 grade by EN388-2003 test.
Example 5
The embodiment provides a preparation method of an ultrahigh molecular weight polyethylene fiber, which comprises the following steps:
(1) adding 800g of boron nitride micron-sized short fiber with the length of 20-30um to 260 ℃, then adding 100g of polyurethane resin (a mixture of hydroxyl-terminated dihydric alcohol and 1, 4-cyclohexane diisocyanate), stirring to form a mixture, and adding 0.35g of calcium stearate, 0.75g of imidazole curing agent and 0.75g of TiO before the beginning of caking 2 Rear bumperStirring at a high speed. Stopping heating, cooling to 50 ℃, transferring to a crusher for crushing, sieving for 300-500 meshes, returning to the crusher for crushing again and sieving treatment if the material can not be sieved. Finally, the modified boron nitride micron-sized short fiber coated with the high molecular polymer is prepared.
(2) And (2) mixing the modified boron nitride micron-sized short fibers and 20kg of ultra-high molecular weight polyethylene powder with the molecular weight of 360 ten thousand and the average particle size of 100 mu m in a ball mill for 15min, adding the mixture into 100kg of white oil, heating the mixture to 50 ℃, and stirring for 2h until the ultra-high molecular weight polyethylene is completely swelled to obtain a mixture.
(3) And (2) blending and extruding the mixed mixture by a double-screw extruder, cooling and forming by a coagulating bath to obtain nascent fibers, extracting, drying and carrying out multistage hot drafting on the nascent fibers to obtain white ultrahigh molecular weight polyethylene ultrahigh cutting-resistant fibers, wherein the dispersion concentration of the boron nitride fibers in the ultrahigh molecular weight polyethylene is 3.84%. Wherein, the temperature of each area of the twin-screw is controlled to be 180-220 ℃, and the drawing ratio is 16.
The fiber has good dyeability, no prickling feeling and comfortable wearing, and the cut-resistant grade is 4 grade according to EN388-2003 test.
Example 6
The embodiment provides a preparation method of an ultrahigh molecular weight polyethylene fiber, which comprises the following steps:
(1) 2.0kg of boron nitride micron-sized short fiber with the length of 40-60um is taken.
(2) The boron nitride micron-sized short fibers, 18kg of ultra-high molecular weight polyethylene powder with the molecular weight of 40 ten thousand and the average particle size of 100um and 1.0kg of master batch of EVA with the relative molecular weight of 2000 are mixed together in a ball mill for 30 min. Then, the mixture was added to 100kg of paraffin oil, heated to 75 ℃ and stirred until the mixture completely swelled.
(3) And (2) blending and extruding the mixed mixture by a double-screw extruder, cooling and forming by a coagulating bath to obtain nascent fibers, extracting, drying and carrying out multistage hot drafting on the nascent fibers to obtain white ultrahigh molecular weight polyethylene ultrahigh cutting-resistant fibers, wherein the dispersion concentration of the boron nitride fibers in the ultrahigh molecular weight polyethylene is 9.5%. Wherein, the temperature of each area of the twin-screw is controlled at 190 ℃ and 230 ℃, and the drawing magnification is 12.
The fiber has good dyeability, no prickling feeling and comfortable wearing, and the cut-resistant grade is 5 grade by an EN388-2003 test.
Example 7
The embodiment provides a preparation method of an ultrahigh molecular weight polyethylene fiber, which comprises the following steps:
(1) 1600g of boron nitride micron-sized short fiber with the length of 20-30um is taken, dissolved in 2L of 5mol/L sodium hydroxide solution, stirred for 12 hours at 120 ℃, washed by deionized water for 3 times after suction filtration, and dried at 60 ℃ to obtain the surface hydroxylated boron nitride micron-sized short fiber.
(2) Preparing a solution from acetone and dilute hydrochloric acid with the pH value of 3 according to a volume ratio of 9:1, adding 100g of a coupling agent KH570, hydrolyzing at 60 ℃ for 1.5h, then adding the surface hydroxylated boron nitride micron-sized short fiber obtained in the step (1) into the solution, mixing with the hydrolyzed coupling agent, stirring at 50 ℃ for 3h, carrying out suction filtration, washing with deionized water for 3 times, and drying to obtain the surface coupling agent modified boron nitride micron-sized short fiber.
(3) And (2) performing ball milling dry mixing on the surface coupling agent modified boron nitride micron-sized short fibers, 20Kg of ultrahigh molecular weight polyethylene powder with the molecular weight of 300 ten thousand and the average particle size of 100 mu m and 1.0Kg of master batch of EVA with the relative molecular weight of 2000 for 20min, putting the mixture into 100Kg of white oil, stirring and mixing for 2h, heating to 75 ℃, stirring and mixing for 2h until the mixture is completely swelled, and obtaining a mixture.
(4) And (2) blending and extruding the mixed mixture by a double-screw extruder, cooling and forming by a coagulating bath to obtain nascent fibers, extracting, drying and carrying out multi-stage hot drawing on the nascent fibers to obtain white ultrahigh molecular weight polyethylene ultrahigh cutting-resistant fibers, wherein the dispersion concentration of the boron nitride fibers in the ultrahigh molecular weight polyethylene is 7.07%. Wherein, the temperature of each area of the twin-screw is controlled at 160-190 ℃, and the drawing ratio is 10.
The fiber has good dyeability, no prickling feeling and comfortable wearing, and the cut-resistant grade is 5 grade by an EN388-2003 test.
Example 8
The embodiment provides a preparation method of an ultrahigh molecular weight polyethylene fiber, which comprises the following steps:
(1) and (3) dissolving 850g of boron nitride micron-sized short fibers with the length of 30-60 microns in 2L of 5mol/L sodium hydroxide solution, stirring for 12 hours at 120 ℃, washing for 3 times by using deionized water after suction filtration, and drying at 60 ℃ to obtain the surface hydroxylated boron nitride micron-sized short fibers.
(2) Preparing acetone and dilute hydrochloric acid with the pH value of 3 into a solution according to the volume ratio of 9:1, adding 55g of a coupling agent KH570, hydrolyzing at 60 ℃ for 1.5h, then adding the surface-hydroxylated boron nitride micron-sized short fiber obtained in the step (1) into the solution, mixing with the hydrolyzed coupling agent, stirring at 50 ℃ for 3h, carrying out suction filtration, washing with deionized water for 3 times, and drying to obtain the surface-coupling-agent-modified boron nitride micron-sized short fiber.
(3) And (3) carrying out dry mixing on the surface coupling agent modified boron nitride micron-sized short fibers and 100g of boron nitride particle powder with the median particle size of 8 mu m in a ball mill for 20min in advance to obtain a dry mixture of boron nitride fibers and boron nitride powder.
(4) And (3) carrying out ball milling dry mixing on the dry mixture and 20Kg of ultra-high molecular weight polyethylene powder with the molecular weight of 300 ten thousand and the average particle size of 100um for 20min, putting the dry mixture and the ultra-high molecular weight polyethylene powder into 100Kg of white oil, stirring and mixing the mixture for 2h, heating the mixture to 75 ℃, and stirring and mixing the mixture for 2h until the mixture is completely swelled to obtain a mixture.
(5) And (2) blending and extruding the mixed mixture by a double-screw extruder, cooling and forming by a coagulating bath to obtain nascent fibers, extracting, drying and carrying out multi-stage hot drawing on the nascent fibers to obtain white ultrahigh molecular weight polyethylene ultrahigh cutting-resistant fibers, wherein the dispersion concentration of the boron nitride fibers in the ultrahigh molecular weight polyethylene is 4.5%. Wherein, the temperature of each area of the twin-screw is controlled at 200-230 ℃, and the drawing magnification is 12.
The fiber has good dyeability, no prickling feeling and comfortable wearing, and the anti-cutting grade is 4 grade according to the EN388-2003 test.
Example 9
The embodiment provides a preparation method of an ultrahigh molecular weight polyethylene fiber, which comprises the following steps:
(1) 1800g of boron nitride micron-sized short fibers with the length of 20-60um and 200g of boron nitride particles with the median particle size of 6-10um are mixed in advance in a mixer to obtain the boron nitride dry powder.
(2) The boron nitride dry mixture and 1.0Kg of EVA with the molecular weight of 18Kg of ultra-high molecular weight polyethylene powder with the molecular weight of 300 ten thousand and the average particle size of 100um and the molecular weight of about 2000 are ball-milled and dry-mixed for 20min, then are put into 100Kg of white oil together, stirred and mixed for 2h, heated to 75 ℃, stirred and mixed for 2h until the mixture is completely swelled, and stirred to obtain the mixture.
(3) And (2) blending and extruding the mixture by a double-screw extruder, cooling and forming by a coagulating bath to obtain nascent fibers, extracting, drying and carrying out multi-stage hot drawing on the obtained nascent fibers to prepare white ultrahigh molecular weight polyethylene ultrahigh cutting-resistant fibers, wherein the dispersion concentration of the boron nitride fibers in the ultrahigh molecular weight polyethylene is 9.5%. Wherein, the temperature of each area of the twin-screw is controlled at 210-240 ℃, and the drawing ratio is 10.
The fiber has good dyeability, no prickling feeling and comfortable wearing, and the cut-resistant grade is 5 grade by an EN388-2003 test.
Comparative example 1
The boron nitride micro-sized short fibers in example 1 were replaced with 1200g of boron nitride particle powder having a median particle size of 12 microns. Other conditions and treatment procedures referring to example 1, ultra-high molecular weight polyethylene ultra-high cut resistant fibers were prepared with a boron nitride dispersion concentration of 7.4% in the ultra-high molecular weight polyethylene. The cut-resistant rating was 4 as tested by EN 388-2003. The prepared fiber yarn has poor cutting resistance and high aging speed.
The ultra-high molecular weight polyethylene fibers prepared in examples 1 to 8 and comparative example 1 were woven into 13-pin protective gloves, and after being worn and used for 1 day (1d) and 20 days (20d) by workers operating in the same place, the performance of the gloves was respectively tested, and the test results were as follows:
the test results show that the anti-cutting grade of fabrics such as gloves woven by the ultra-high molecular weight polyethylene fiber can reliably and stably reach EN388-2003 standard grade 4-5. More importantly, the ultra-high molecular weight polyethylene fiber produced according to the invention is white without adding pigment, and the fiber yarn and the textile are easy to color.
Furthermore, as can be seen from the comparison between examples 2-8 and example 1, the cut resistance of example 1 decays rapidly, mainly due to the poor affinity, poor dispersibility and precipitation of boron nitride fibers in the ultra-high molecular weight polyethylene matrix. Example 2 and example 1 at the same content of boron nitride fiber, the cut resistance data of example 2 is substantially the same as that of example 1, but the decay rate of the cut resistance is obviously slower, and the prepared fiber filament is softer and has better spinnability than that of example 1, and the content concentration can be about 14%.
Comparative example 1 although the boron nitride content also reached 7.4%, the cut resistance was 1 rank weaker than that of the polyethylene fiber yarn reinforced with the same content of boron nitride micro-sized short fibers (example 1). Therefore, the cutting resistance of the ultra-high molecular weight polyethylene fiber obtained by replacing the boron nitride particle powder with the boron nitride micron-sized short fiber is greatly enhanced. In addition, the polyethylene fibers of example 1 and comparative example 1 both exhibited a certain degree of burring after 20 days of use, indicating that some boron nitride short fibers or granular powder was exuded.
In examples 6 and 8, the content of the boron nitride micron-sized short fiber is the highest, and the cutting resistance is the best, but if the content is too high, the spinnability of the fiber yarn is deteriorated, so that the content of the boron nitride is not too high, and the content is optimally 9 to 9.5 percent. In example 7, after the boron nitride micron-sized short fibers are modified by the coupling agent, the boron nitride particle powder or the EVA matrix doped with a certain proportion is introduced, so that the bonding stability of the boron nitride micron-sized short fibers in the polyethylene fibers can be significantly increased, and as can be seen from the use of 20d data, the cutting resistance and aging are not significant, and compared with example 1, the cutting resistance of the polyethylene fiber yarn in example 7 is slowly attenuated. In examples 3, 4 and 5, the dispersibility of the boron nitride fiber in the polyethylene fiber matrix can be improved and the anti-aging capability of the cutting resistance can be improved by modifying the coupling agent, coating the boron nitride fiber or doping the boron nitride fiber with a certain proportion of EVA.
In addition, according to long-term observation and research, the abrasion of the mixing equipment and the extrusion molding equipment in the preparation process is not obvious in examples 1 to 8 and comparative example 1, which are mainly caused by the self-lubricating property of the boron nitride, so that the equipment loss speed is reduced.