A high-strength wear-resistant polyethylene fiber and its preparation method

Abstract

The invention discloses a high-strength wear-resistant polyethylene fiber and a preparation method thereof, belonging to the technical field of polyethylene fibers. The high-strength wear-resistant polyethylene fiber provided by the invention comprises the following components by weight: 100 parts of ultra-high molecular weight polyethylene, 10-20 parts of inorganic fillers, 5-10 parts of compatibilizers, 3-10 parts of cross-linking agents, 0.5-2 parts of peroxides, 0.5-2 parts of lubricants, and 0.1-2 parts of antioxidants; the cross-linking agent is a poly-aromatic ring structure terminated by polyene groups; by adding a cross-linking agent with a high steric hindrance structure of the poly-aromatic ring structure terminated by polyene groups, the free volume between the cross-linking points of polyethylene and the molecular chains is increased, the processing performance is improved, and the cross-linking agent with the poly-aromatic ring structure further improves the thermal stability and mechanical properties of the polyethylene fiber, so that the polyethylene fiber has high strength and good wear resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of polyethylene fibers, and specifically to a high-strength wear-resistant polyethylene fiber and a preparation method thereof. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber is a high-performance fiber prepared from polyethylene with a relative molecular weight exceeding 1.5 million. It has excellent mechanical properties, and also has a small density, good weather resistance, chemical corrosion resistance, low temperature resistance, bending resistance, cutting resistance, impact resistance, low electrical conductivity, high transmittance to medium-wavelength infrared, and certain waterproof properties. It is widely used in military equipment, aerospace, ocean engineering, safety protection, transportation, sports equipment, biomedical, home textile products and other special fields. In recent years, with the increasing emphasis on the development of marine resources, the application demand for UHMWPE fiber ropes has increased suddenly. At the same time, higher requirements for the wear resistance of UHMWPE fibers have also been put forward during the use process. Due to the presence of molecular chain ends and amorphous defects in UHMWPE fibers, and the relatively small surface hardness of UHMWPE fibers, when UHMWPE fibers rub against the surfaces of high-hardness substances such as metal and ceramic particles, the surface of UHMWPE fibers is extremely easy to be damaged by the micro-protrusions on the surface of metal or ceramic particles, resulting in wear on the fiber surface. And the intermolecular force between the molecular chains in UHMWPE fibers is relatively poor. When the damaged UHMWPE fibers continue to rub against the above high-hardness substances, the wear area on the surface of UHMWPE fibers will rapidly expand, easily leading to the fracture of UHMWPE fibers and causing wear failure. It can be seen that the insufficient wear resistance of UHMWPE fibers has restricted the application and further development of UHMWPE fibers and their products. Improving the strength and wear resistance of UHMWPE fibers has become an urgent problem to be solved in the current UHMWPE fiber industry. The research on the wear-resistant modification of UHMWPE fibers mainly includes methods such as blending modification, cross-linking modification, and construction of surface wear-resistant coatings. For example, CN116876095B discloses the blending modification of UHMWPE with hyperbranched modified carbon nanotubes and graphene, and adding DCP for cross-linking to obtain polyethylene fibers with wear-resistant and cut-resistant properties. However, the cross-linked network obtained by DCP cross-linking is relatively tight. In the preparation process of polyethylene fibers, it is difficult for the solvent to enter the polyethylene network to swell polyethylene, resulting in a low gel content of polyethylene, increasing the processing difficulty of polyethylene fibers. In addition, the problem of low melting point of UHMWPE and easy degradation and poor thermal stability during high-temperature spinning has not been solved. Summary of the Invention

[0003] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a high-strength wear-resistant polyethylene fiber and a preparation method thereof, by adding a cross-linking agent with a high steric hindrance structure of a polyaromatic ring structure terminated with a polyene functional group, thereby improving the processing performance, wear resistance and thermal stability of the polyethylene fiber.

[0004] The technical solution for achieving the purpose of the present invention is as follows:

[0005] A high-strength wear-resistant polyethylene fiber comprises the following components by weight: 100 parts of ultra-high molecular weight polyethylene, 10-20 parts of inorganic filler, 5-10 parts of compatibilizer, 3-10 parts of cross-linking agent, 0.5-2 parts of peroxide, 0.5-2 parts of lubricant, and 0.1-2 parts of antioxidant; the structure of the cross-linking agent is shown in Formula 1:

[0006]

[0007] Specifically, the preparation method of the cross-linking agent comprises the following steps:

[0008] S1. reacting 2,4,6-tris(4-hydroxyphenyl)-1,3,5-triazine with 3-chloro-1,2-propanediol to obtain 2,4,6-tris(4-dihydroxypropylphenyl)-1,3,5-triazine;

[0009] S2. reacting ethyl 4-hydroxybenzoate with allyl bromide to obtain ethyl 4-allyloxybenzoate; hydrolyzing ethyl 4-allyloxybenzoate under alkaline conditions to obtain 4-allyloxybenzoic acid; reacting 4-allyloxybenzoic acid with thionyl chloride to obtain 4-allyloxybenzoyl chloride;

[0010] S3. React 4-allyloxybenzoyl chloride with 2,4,6-tris(4-dihydroxypropylphenyl)-1,3,5-triazine to obtain the crosslinking agent.

[0011] Preferably, the peroxide is at least one of di-tert-butyl peroxide or dicumyl peroxide.

[0012] Preferably, the antioxidant is at least one of a hindered phenol antioxidant, a phosphite antioxidant or a thioether antioxidant.

[0013] Preferably, the lubricant is at least one of stearic acid, calcium stearate or zinc stearate.

[0014] Preferably, the inorganic filler includes a flaky filler or a granular filler; the flaky filler is at least one of mica flakes, graphite flakes or talc flakes, and the granular filler is at least one of calcium carbonate, talcum powder or silicon dioxide.

[0015] Preferably, the inorganic filler is a compound of flaky filler and granular filler, and the mass ratio is (1-3):(1-3).

[0016] Preferably, the compatibilizer is at least one of ethylene-acrylate-maleic anhydride copolymer or ethylene-acrylate-glyceryl methacrylate random copolymer.

[0017] Another object of the present invention is to protect a method for preparing the high-strength wear-resistant polyethylene fiber, comprising the following steps: after screening the ultra-high molecular weight polyethylene powder, mixing it with a solvent, adding a cross-linking agent, a peroxide, a lubricant and an antioxidant, and fully stirring at 100-150 °C to obtain a suspension; adding the suspension into the barrel of a twin-screw extruder from the main feeding port, feeding the flaky filler, the granular filler and the compatibilizer from the side feeding port, and melt-extruding to obtain a polyethylene non-solution mixture; filtering the polyethylene non-solution mixture and then spinning it, cooling after spinning to obtain a polyethylene gel fiber; extracting the polyethylene gel fiber with an extractant to remove the solvent, and performing hot stretching after drying, and shaping and winding to obtain the high-strength wear-resistant polyethylene fiber.

[0018] Another object of the present invention is to protect the application of the high-strength wear-resistant polyethylene fiber in special protective gloves and ropes.

[0019] Beneficial effects

[0020] The present invention provides a high-strength wear-resistant polyethylene fiber, its preparation method and application. By adding a cross-linking agent with a high steric hindrance structure of a multi-aromatic ring structure capped with a polyene functional group to ultra-high molecular weight polyethylene, a radical polymerization reaction is initiated under high-temperature conditions to introduce a high steric hindrance multi-aromatic ring structure. Among them, multiple vinyl structures as capping groups provide multiple cross-linking points for the cross-linking agent, and a dense cross-linking network can be formed between the polyethylene molecular chains. At the same time, the high steric hindrance structure increases the free volume between the molecular chains and increases the flexibility of the polyethylene fiber. During the swelling period of preparing the polyethylene fiber, the polyethylene is not cross-linked or has a low degree of cross-linking, and the solvent molecules can penetrate between the polyethylene molecular chains for swelling, thereby increasing the gel content and improving the processing performance. During the spinning period, under the action of the high spinning temperature, a radical polymerization reaction between the polyethylene and the cross-linking agent is initiated. The introduction of the multi-aromatic ring structure improves the thermal stability of the polyethylene fiber, alleviates the problem of high-temperature degradation of the polyethylene, and ensures the tensile strength and wear resistance of the polyethylene fiber, so that the prepared polyethylene fiber meets the use requirements of ship ropes and special protective gloves. Description of the drawings

[0021] Figure 1 It is a schematic diagram of the synthesis route of the cross-linking agent. Detailed implementation manners

[0022] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0023] In the embodiments, unless otherwise specified, the experimental methods used are all conventional methods, and the materials, reagents, etc. used, unless otherwise specified, can all be obtained from commercial channels.

[0024] The raw materials used in the examples and comparative examples are described as follows:

[0025] Ultra-high molecular weight polyethylene: Ultra-high molecular weight polyethylene powder, with a molecular weight of 1.5 million, grade UH150P, Daqing Petrochemical;

[0026] Flaky filler: Flake graphite, SY150, Shandong Shuangyu Carbon Co., Ltd.;

[0027] Granular filler: Silicon dioxide, 1250 mesh, Lingshou County Jianshi Mineral Powder Factory;

[0028] Compatibilizer 1: Ethylene-acrylate-glyceryl methacrylate random copolymer, AX8840, Arkema;

[0029] Compatibilizer 2: Ethylene-acrylate-maleic anhydride copolymer, 2210, Arkema;

[0030] Peroxide: Di-tert-butyl peroxide, DTBPO, 99%;

[0031] Lubricant: Stearic acid, commercially available;

[0032] Antioxidant: A compound of antioxidant 1010 and antioxidant 168 with a mass ratio of 1:1, commercially available;

[0033] Solvent: White oil 70#, Shanghai Shanyang Lubricating Oil Co., Ltd.;

[0034] Extraction agent: Dichloromethane, commercially available;

[0035] Crosslinking agent 1: The preparation method is as follows:

[0036] S1. Dissolve 1 mol of 2,4,6-tris(4-hydroxyphenyl)-1,3,5-triazine in a pre-dried mixed solution of acetone and DMSO, add 3 mol of anhydrous potassium carbonate, under nitrogen purge, dropwise add 3.2 mol of 3-chloro-1,2-propanediol, and reflux the reaction at 80 °C for 48 hours. Monitor the reaction progress by thin-layer chromatography (TLC). After the reaction is completed, cool it to room temperature and pour it into 100 ml of deionized water. Then add dichloromethane to separate the organic layer, wash it with deionized water twice again, separate, dry it with anhydrous magnesium sulfate, and evaporate the solvent to obtain 2,4,6-tris(4-dihydroxypropylphenyl)-1,3,5-triazine;

[0037] S2. Dissolve 1 mol of ethyl 4-hydroxybenzoate in a pre-dried mixed solution of acetone and DMSO, add 1 mol of anhydrous potassium carbonate, under nitrogen purge, dropwise add 1.02 mol of allyl bromide, and reflux the reaction at 60 °C for 48 hours. Monitor the reaction progress by thin-layer chromatography (TLC). After the reaction is completed, cool it to room temperature and pour it into 100 ml of deionized water, acidify it with a few drops of hydrochloric acid, then add dichloromethane to separate the organic layer, wash it with deionized water twice again, separate, dry it with anhydrous magnesium sulfate, and evaporate the solvent to obtain ethyl 4-allyloxybenzoate;

[0038] Prepare a potassium hydroxide solution with a concentration of 0.5 mol / L, and the solvent is 5% ethanol aqueous solution. Mix 3 g of ethyl 4-allyloxybenzoate with 150 ml of potassium hydroxide solution, reflux the reaction at 80 °C for 12 hours. After the reaction is completed, cool it to room temperature, acidify it with 10% hydrochloric acid solution, filter the precipitate, recrystallize it in absolute ethanol, and further dry it under vacuum to obtain 4-allyloxybenzoic acid;

[0039] Mix 0.3 mol of 4-allyloxybenzoic acid with 50 ml of thionyl chloride, reflux the reaction at 80 °C for 6 hours, and distill off the excess thionyl chloride under reduced pressure to obtain 4-allyloxybenzoyl chloride;

[0040] S3. Under a nitrogen atmosphere and in an ice bath, mix 0.62 mol of 4-allyloxybenzoyl chloride with 0.1 mol of 2,4,6-tris(4-dihydroxypropylphenyl)-1,3,5-triazine, add 1 g of 4-dimethylaminopyridine, 100 ml of tetrahydrofuran, and 100 ml of triethylamine and mix well. Stir it in an ice bath for 8 hours and then leave it at room temperature for 5 days; then mix the reactant with 500 ml of acidified aqueous solution (pH = 5, acetic acid), filter, wash the solid with deionized water and ethanol in turn, and then purify it by column chromatography. The solvent is n-hexane / ethyl acetate with a ratio of 4:1 to obtain the crosslinker. The reaction process is as Figure 1 shown;

[0041] Crosslinking agent 2: Triallyl cyanurate; 98%, Shanghai Merck Chemical Technology Co., Ltd.;

[0042] Unless otherwise specified, the component raw materials used in each example and comparative example of the present invention are all commercially available raw materials, and the component raw materials used in each parallel experiment are of the same kind.

[0043] Example 1

[0044] A high-strength wear-resistant polyethylene fiber is prepared by: screening ultra-high molecular weight polyethylene powder with a 60-mesh sieve to remove larger-sized particles, mixing the ultra-high molecular weight polyethylene powder with white oil in a mixing kettle at a concentration of 10 wt% of the ultra-high molecular weight polyethylene powder, adding a crosslinking agent, a peroxide, a lubricant, and an antioxidant, and fully stirring at 120 °C to obtain a suspension;

[0045] Adding the suspension into the barrel of a twin-screw extruder, with the feeding machine speed at 1.0 rpm and the screw speed at 200 rpm, the temperatures of each section of the twin-screw are respectively set at 115 °C, 130 °C, 150 °C, 150 °C, 150 °C, and the die head temperature is 160 °C. Adding sheet-shaped filler, granular filler, and compatibilizer from the side feeding port, and melt-extruding to obtain a polyethylene non-solution mixture;

[0046] Filtering the obtained polyethylene non-solution mixture with a 1200-mesh filter screen, installing a spinneret assembly for spinning. The polyethylene non-solution mixture is extruded through a single-hole spinneret with a diameter of 0.9 mm, and after passing through a gas gap layer (<1 cm), it enters a cold water bath for quenching to form polyethylene gel filaments. The spinning temperature is controlled at 230 - 250 °C, and the twin-screw speed is 9.6 rpm. The speed of the collecting roller is such that the polyethylene gel filaments are exactly in a straight state during the spinning process. During the spinning process, the polyethylene undergoes a free radical polymerization reaction under the action of high temperature to form a tight crosslinked network, and the introduction of a multi-aromatic ring structure also reduces the high-temperature degradation of polyethylene, further protecting the mechanical properties of polyethylene.

[0047] Let the polyethylene gel filaments prepared by spinning stand at room temperature for 24 hours to allow the polyethylene gel filaments to fully undergo phase separation, and then place them in a dichloromethane extractant with a bath ratio of 20:1 for ultrasonic extraction operation to remove white oil. The ultrasonic frequency is 53 kHz, and each sample is extracted 3 times, 6 minutes each time. Dry to remove the residual extractant in the polyethylene gel filaments to obtain polyethylene dry gel fibers; perform three-stage hot stretching on the polyethylene dry gel fibers at temperatures of 90 °C, 110 °C, and 120 °C respectively, with stretching multiples of 15, 2, and 1.4 respectively, to prepare high-strength wear-resistant polyethylene fibers. The formula of the high-strength wear-resistant polyethylene fibers is shown in Table 1.

[0048] Table 1 Specific components and parts of high-strength wear-resistant polyethylene fibers

[0049]

[0050]

[0051] The following performance tests were carried out on the prepared polyethylene fibers, and the results are shown in Table 2:

[0052] (1) Tensile strength and elongation at break: Take 1 m of polyethylene fiber, and weigh its mass multiple times using an electronic analytical balance to obtain its average mass of m (g), with the value accurate to 0.1 mg. According to the formula D = m×10000 (dtex), the fineness value D (dtex) of the fiber can be converted. Under the conditions of a gauge length of 200 mm and a tensile speed of 200 mm·min -1 , use a DXLL-20000 universal mechanical testing machine to measure the breaking strength T (cN) of the polyethylene fiber. According to the formula fiber breaking strength = T / D (cN·dtex -1 ), the breaking strength of the fiber can be calculated. Before the strength test, apply a pre-tension of 0.10 cN·dtex -1 to the UHMWPE drawn fiber to ensure that the fiber is in a straight state before testing, so as to ensure the accuracy of the fiber elongation at break. Each sample was tested 15 times, and the average value was taken.

[0053] (2) Abrasion resistance: Refer to FZ / T50025-2014 "Test Method for Abrasion Resistance of Ultra-High Molecular Weight Polyethylene Filaments" to test the abrasion resistance of polyethylene fibers; among them, the friction roller of the reciprocating fiber abrasion tester has a diameter of 10 mm, and the surface is coated with W20(02) metallographic sandpaper. The abrasive material on the sandpaper surface is SiC, and the corresponding abrasive particle size is 20 μm. During the friction process of the fiber, the friction roller makes a reciprocating motion, the reciprocating distance is 25 mm, and the reciprocating frequency is 95 times·minute -1 ; during the friction test, control the fiber tension to 0.45 cN·dtex -1 , and the wrap angle of the fiber around the friction roller is 110°; define the number of reciprocations of the friction roller during the period from the start of the fiber abrasion resistance test to the failure of the fiber due to wear as the maximum friction number (Nf) of the fiber; control the test environment temperature at 25 °C and the humidity at about 60%.

[0054] (3) Heat resistance: Conduct thermogravimetric analysis tests on the polyethylene fibers of the examples and comparative examples, and use the temperature (T10%) when the mass loss percentage reaches 10% to characterize the heat resistance of the material. The higher the T10% temperature, the better the heat resistance of the material.

[0055] Table 2 Performance test results of high-strength wear-resistant polyethylene fibers

[0056]

[0057] It can be seen from Example 3 and Comparative Examples 1 and 2 that the mechanical properties, wear resistance and heat resistance of the chemically crosslinked ultra-high molecular weight polyethylene are significantly improved compared with those of the uncrosslinked ultra-high molecular weight polyethylene, and the crosslinking agent provided in this application has a more obvious modification effect on the polyethylene fiber modified by the existing crosslinking agent. The tensile strength of the polyethylene fiber prepared by modifying with the crosslinking agent having a high steric hindrance structure of a multi-aromatic ring structure capped with a polyene functional group is 30 cN·dtex -1 Above, the wear resistance Nf is greater than 10,000 times, and the thermal decomposition temperature is greater than 430 °C, showing broad application prospects.

[0058] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A high-strength wear-resistant polyethylene fiber, characterized in that, By weight parts, it includes the following components: 100 parts of ultra-high molecular weight polyethylene, 10 - 20 parts of inorganic filler, 5 - 10 parts of compatibilizer, 3 - 10 parts of crosslinking agent, 0.5 - 2 parts of peroxide, 0.5 - 2 parts of lubricant, 0.1 - 2 parts of antioxidant; the structure of the crosslinking agent is shown in Formula 1:

2. The high-strength wear-resistant polyethylene fiber according to claim 1, wherein The preparation method of the crosslinking agent includes the following steps: S1. React 2,4,6-tris(4-hydroxyphenyl)-1,3,5-triazine with 3-chloro-1,2-propanediol to obtain 2,4,6-tris(4-dihydroxypropylphenyl)-1,3,5-triazine; S2. React ethyl 4-hydroxybenzoate with allyl bromide to obtain ethyl 4-allyloxybenzoate; ethyl 4-allyloxybenzoate is hydrolyzed under alkaline conditions to obtain 4-allyloxybenzoic acid; 4-allyloxybenzoic acid reacts with thionyl chloride to obtain 4-allyloxybenzoyl chloride; S3. React 4-allyloxybenzoyl chloride with 2,4,6-tris(4-dihydroxypropylphenyl)-1,3,5-triazine to obtain the crosslinking agent.

3. The high-strength wear-resistant polyethylene fiber according to claim 1, wherein, The peroxide is at least one of di-tert-butyl peroxide or dicumyl peroxide.

4. The high-strength wear-resistant polyethylene fiber according to claim 1, wherein The antioxidant is at least one of hindered phenol antioxidants, phosphite antioxidants or thioether antioxidants.

5. The high-strength wear-resistant polyethylene fiber according to claim 1, characterized in that, The lubricant is at least one of stearic acid, calcium stearate or zinc stearate.

6. The high-strength wear-resistant polyethylene fiber according to claim 1, characterized in that, The inorganic filler includes flaky filler or granular filler; the flaky filler is at least one of mica flakes, flake graphite or talc flakes, and the granular filler is at least one of calcium carbonate, talcum powder or silica.

7. The high-strength wear-resistant polyethylene fiber according to claim 6, wherein The inorganic filler is a compound of flaky filler and granular filler, and the mass ratio is (1 - 3):(1 - 3).

8. The high-strength wear-resistant polyethylene fiber according to claim 1, characterized in that, The compatibilizer is at least one of ethylene-acrylate-maleic anhydride copolymer or ethylene-acrylate-glycerol methacrylate random copolymer.

9. The preparation method of the high-strength wear-resistant polyethylene fiber according to any one of claims 1 to 8, characterized in that, It includes the following steps: After screening ultra-high molecular weight polyethylene powder, mix it with a solvent, add a crosslinking agent, peroxide, lubricant and antioxidant, and fully stir at 100 - 150 °C to obtain a suspension; add the suspension into the barrel of a twin-screw extruder from the main feeding port, feed the flaky filler, granular filler and compatibilizer from the side feeding port, and melt and extrude to obtain a polyethylene non-solution mixture; filter the polyethylene non-solution mixture and then carry out spinning, cool after spinning to obtain polyethylene gel filaments; use an extractant to extract the polyethylene gel filaments to remove the solvent, and after drying, carry out hot stretching and shaping winding to obtain high-strength wear-resistant polyethylene fibers.

10. The application of the high-strength wear-resistant polyethylene fiber according to any one of claims 1 - 8 in special protective gloves, ropes.

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