High-strength wear-resistant polyethylene fiber and preparation method thereof

Abstract

The invention discloses a high-strength wear-resistant polyethylene fiber and a preparation method thereof, and belongs to the technical field of polyethylene fibers.The high-strength wear-resistant polyethylene fiber is prepared from, by weight, 100 parts of ultra-high molecular weight polyethylene, 10-20 parts of inorganic filler, 5-10 parts of compatilizer, 3-10 parts of cross-linking agent, 0.5-2 parts of peroxide and 0.5-2 parts of lubricant. 0.1 to 2 parts of an antioxidant; the cross-linking agent is of a polyalkenyl-terminated multi-aromatic ring structure; by adding the cross-linking agent with a high steric hindrance structure and a polyalkenyl functional group terminated multi-aromatic ring structure, the free volume between a cross-linking point and a molecular chain of polyethylene is increased, the processability is improved, and the thermal stability and the mechanical property of the polyethylene fiber are further improved by the cross-linking agent with the multi-aromatic ring structure; the polyethylene fiber is high in strength and good in wear resistance.

Description

Technical Field

[0001] The invention relates to the technical field of polyethylene fibers, in particular 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 made of polyethylene with a relative molecular weight of more than 1.5 million. It has excellent mechanical properties, low density, good weather resistance, chemical corrosion resistance, low temperature resistance, bending resistance, cutting resistance, impact resistance, low conductivity, high transmittance to medium-wavelength infrared and certain waterproofness. It is widely used in military equipment, aerospace, marine engineering, safety protection, transportation, sports equipment, biomedicine, home textile products and other special fields. In recent years, with the increasing attention paid to the development of marine resources, the demand for the application of UHMWPE fiber ropes has increased sharply, and higher requirements have been put forward for the wear resistance of UHMWPE fibers during use. 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 surface of high-hardness materials such as metals and ceramic particles, the surface of UHMWPE fibers is easily damaged by the micro-convex bodies on the surface of metal or ceramic particles, resulting in wear on the fiber surface. However, the interaction force between molecular chains in UHMWPE fiber is relatively poor. When the UHMWPE fiber with surface damage continues to rub against the above-mentioned high hardness material, the wear area on the surface of the UHMWPE fiber will expand rapidly, which can easily lead to the breakage of the UHMWPE fiber and the wear failure. It can be seen that the lack of wear resistance of UHMWPE fiber has limited the application and further development of UHMWPE fiber and its products. Improving the strength and wear resistance of UHMWPE fiber has become an urgent problem to be solved in the current UHMWPE fiber industry. The research on wear resistance modification of UHMWPE fiber mainly includes methods such as blending modification, cross-linking modification, and surface wear-resistant coating construction. For example, CN116876095B discloses that UHMWPE is blended and modified by hyperbranched modified carbon nanotubes and graphene, and DCP is added for cross-linking. The obtained polyethylene fiber has the performance of wear resistance and cutting resistance, but the cross-linked network obtained by DCP cross-linking is relatively tight. In the preparation process of polyethylene fiber, it is difficult for the solvent to enter the polyethylene network to swell the polyethylene, which makes the gel content of polyethylene low, increasing the processing difficulty of polyethylene fiber. In addition, the problems of UHMWPE's low melting point, easy degradation during high-temperature spinning, and poor thermal stability have 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 diisopropylbenzene 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 a flake filler and a granular filler in a mass ratio of (1-3): (1-3).

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

[0017] Another object of the present invention is to protect the preparation method of the high-strength and wear-resistant polyethylene fiber, which comprises the following steps: ultra-high molecular weight polyethylene powder is screened and mixed with a solvent, a cross-linking agent, a peroxide, a lubricant and an antioxidant are added, and the suspension is fully stirred at 100-150°C to obtain a suspension; the suspension is added into the barrel of a twin-screw extruder from a main feed port, and a flaky filler, a granular filler and a compatibilizer are fed from a side feed port, and the polyethylene non-solution mixture is melt-extruded to obtain a polyethylene non-solution mixture; the polyethylene non-solution mixture is filtered and then spun, and the polyethylene gel filaments are cooled after spinning to obtain polyethylene gel filaments; the polyethylene gel filaments are extracted with an extractant to remove the solvent, and the solvent is removed, and the polyethylene gel filaments are heat-stretched after drying, and the high-strength and wear-resistant polyethylene fibers are obtained by shaping and winding.

[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 and a preparation method and application thereof. A cross-linking agent with a high steric hindrance structure of a polyaromatic ring structure terminated with a polyolefin functional group is added to ultra-high molecular weight polyethylene, and a free radical polymerization reaction is initiated under high temperature conditions to introduce a polyaromatic ring structure with high steric hindrance, wherein the multiple olefin structures as the end-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 has not yet been cross-linked or the degree of cross-linking is low, 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 free radical polymerization reaction between the polyethylene and the cross-linking agent is initiated, and the introduction of the polyaromatic ring structure improves the thermal stability of the polyethylene fiber, alleviates the high temperature degradation problem 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the synthesis route of the cross-linker. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

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

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

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

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

[0028] Compatibilizer 1: Ethylene-acrylate-methacrylate glycerol 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 in a mass ratio of 1:1, commercially available;

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

[0034] Extraction solvent: dichloromethane, commercially available;

[0035] Cross-linking 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 mixed solution of acetone and DMSO from which water has been removed in advance, add 3 mol of anhydrous potassium carbonate, add 3.2 mol of 3-chloro-1,2-propylene glycol dropwise under nitrogen purge conditions, react under condensation reflux at 80° C. for 48 hours, monitor the reaction progress by thin layer chromatography TLC, and after the reaction is completed, cool at room temperature and pour into 100 ml of deionized water, then add dichloromethane to separate the organic layer, add deionized water again to wash twice, separate, dry with anhydrous magnesium sulfate, and evaporate to remove 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 mixed solution of acetone and DMSO from which water has been removed in advance, add 1 mol of anhydrous potassium carbonate, add 1.02 mol of allyl bromide dropwise under nitrogen purge conditions, react under condensation reflux at 60° C. for 48 hours, monitor the reaction progress by thin layer chromatography TLC, and after the reaction is completed, cool at room temperature and pour into 100 ml of deionized water, add a few drops of hydrochloric acid to acidify, then add dichloromethane to separate the organic layer, add deionized water again to wash twice, separate, dry using anhydrous magnesium sulfate, and evaporate to remove the solvent to obtain ethyl 4-allyloxybenzoate;

[0038] A potassium hydroxide solution with a concentration of 0.5 mol / L and a 5% ethanol aqueous solution as solvent are prepared, 3 g of ethyl 4-allyloxybenzoate is mixed with 150 ml of the potassium hydroxide solution, and the mixture is refluxed at 80° C. for 12 hours. After the reaction is completed, the mixture is cooled at room temperature, acidified with a 10% hydrochloric acid solution, the precipitate is filtered and recrystallized in anhydrous ethanol, and further vacuum dried to obtain 4-allyloxybenzoic acid;

[0039] 0.3 mol of 4-allyloxybenzoic acid was mixed with 50 ml of thionyl chloride, and the mixture was refluxed at 80°C for 6 hours, and the excess thionyl chloride was removed by distillation under reduced pressure to obtain 4-allyloxybenzoyl chloride;

[0040] S3. Under nitrogen atmosphere and ice bath conditions, 0.62 mol of 4-allyloxybenzoyl chloride was mixed with 0.1 mol of 2,4,6-tris(4-dihydroxypropylphenyl)-1,3,5-triazine, 1 g of 4-dimethylaminopyridine, 100 ml of tetrahydrofuran and 100 ml of triethylamine were added and mixed evenly, stirred for 8 hours under ice bath conditions and then placed at room temperature for 5 days; the reactants were then mixed with 500 ml of an acidified aqueous solution (pH 5, acetic acid), filtered, and the solid was washed with deionized water and ethanol in turn, and then purified by column chromatography, the solvent was 4:1 hexane / ethyl acetate, to obtain a crosslinking agent, and the reaction process was as follows: Figure 1 As shown;

[0041] Cross-linking agent 2: triallyl cyanurate; 98%, Shanghai Myrel Biochemical Technology Co., Ltd.;

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

[0043] Example 1

[0044] A high-strength wear-resistant polyethylene fiber, the preparation method comprising: sieving ultra-high molecular weight polyethylene powder with a 60-mesh sieve to remove particles with larger particle sizes, mixing the ultra-high molecular weight polyethylene powder with white oil in a mixing kettle at a concentration of 10wt% of the ultra-high molecular weight polyethylene powder, adding a cross-linking agent, a peroxide, a lubricant and an antioxidant, and fully stirring at 120°C to obtain a suspension;

[0045] The suspension is added into the barrel of a twin-screw extruder, the feeder speed is 1.0 rpm, the screw speed is 200 rpm, the temperatures of each section of the twin-screw are set to 115°C, 130°C, 150°C, 150°C, 150°C, respectively, the die temperature is 160°C, and the flaky filler, granular filler and compatibilizer are fed from the side feed port, and melt extruded to obtain a polyethylene non-solution mixture;

[0046] The polyethylene non-solution mixture was filtered through a 1200-mesh filter, and a spinneret assembly was installed for spinning. The polyethylene non-solution mixture was extruded through a 0.9 mm diameter single-hole spinneret, and passed through an air gap layer (<1 cm) and then quenched in a cold water bath to form polyethylene gel filaments. The spinning temperature was controlled at 230-250°C, the twin-screw speed was 9.6 rpm, and the collecting roller speed was such that the polyethylene gel filaments were just in a straightened state during the spinning process. During the spinning process, polyethylene underwent free radical polymerization under high temperature to form a tight cross-linked network. At the same time, the introduction of a polyaromatic ring structure also reduced the high-temperature degradation of polyethylene, thereby further protecting the mechanical properties of polyethylene.

[0047] The polyethylene gel fibers obtained by spinning were allowed to stand at room temperature for 24 hours to allow the polyethylene gel fibers to fully separate phases, and then placed in a dichloromethane extractant with a bath ratio of 20:1 for ultrasonic extraction to remove white oil, with an ultrasonic frequency of 53kHz, and each sample was extracted 3 times, each for 6 minutes. The residual extractant in the polyethylene gel fibers was removed by drying to obtain polyethylene dry gel fibers; the polyethylene dry gel fibers were subjected to three-stage heat stretching at 90°C, 110°C and 120°C, respectively, with stretching multiples of 15, 2 and 1.4, respectively, to obtain high-strength wear-resistant polyethylene fibers, the formula of which is shown in Table 1.

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

[0049]

[0050]

[0051] The obtained polyethylene fiber was subjected to the following performance tests, and the results are shown in Table 2:

[0052] (1) Tensile strength and elongation at break: Take 1m of polyethylene fiber and weigh it several times using an electronic analytical balance to obtain its average mass m (g), with an accuracy of 0.1mg. According to the formula D = m × 10000 (dtex), the fiber fineness D (dtex) can be converted to the value of the fiber. When the clamping distance is 200mm and the stretching speed is 200mm·min -1 Under the conditions, the DXLL-20000 universal mechanical testing machine was used to measure the breaking strength T (cN) of polyethylene fibers. According to the formula, fiber breaking strength = T / D (cN dtex -1 ) can be used to calculate the breaking strength of the fiber. Before the strength test, 0.10 cN·dtex is applied to the UHMWPE tensile fiber. -1 The pre-tension of the fiber is ensured to be in a straight state before the test to ensure the accuracy of the fiber elongation at break. Each sample is tested 15 times and the average value is taken.

[0053] (2) Wear resistance: The wear resistance of polyethylene fiber was tested with reference to FZ / T50025-2014 "Test method for wear resistance of ultra-high molecular weight polyethylene filaments". The diameter of the friction roller of the reciprocating fiber wear tester is 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 size is 20 μm. During the friction process of the fiber, the friction roller reciprocates, the reciprocating distance is 25 mm, and the reciprocating frequency is 95 times / minute. -1 ; During the friction test, the fiber tension was controlled to 0.45 cN·dtex -1 The covering angle of the fiber-coated friction roller is 110°; the number of reciprocating times of the friction roller from the start of the fiber wear resistance test to the fiber wear and fracture failure is defined as the maximum friction number of the fiber (Nf); the test environment temperature is controlled at 25°C and the humidity is around 60%.

[0054] (3) Heat resistance: The polyethylene fibers of the examples and comparative examples were subjected to thermogravimetric analysis tests, and the temperature at which the mass loss percentage reached 10% (T10%) was used 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 fiber

[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 ultra-high molecular weight polyethylene after chemical crosslinking are significantly improved compared with the uncrosslinked ultra-high molecular weight polyethylene, and the modification effect of the crosslinking agent provided in the present application is more obvious than that of the polyethylene fiber modified by the existing crosslinking agent. The tensile strength of the polyethylene fiber obtained after the crosslinking agent modified with a high steric hindrance structure of a polyolefin functional group-terminated polyaromatic ring structure is 30 cN·dtex. -1 The above, the wear performance Nf is greater than 10000 times, the thermal decomposition temperature is greater than 430 ℃, and it has broad application prospects.

[0058] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-strength wear-resistant polyethylene fiber, characterized in that: The composition includes 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:

2. The high-strength wear-resistant polyethylene fiber according to claim 1, characterized in that: The preparation method of the cross-linking agent comprises the following steps: 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; 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; 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, characterized in that: 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, characterized in that: The antioxidant is at least one of a hindered phenol antioxidant, a phosphite antioxidant or a thioether antioxidant.

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 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.

7. The high-strength wear-resistant polyethylene fiber according to claim 6, characterized in that: The inorganic filler is a compound of a flake filler and a 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-methacrylate glycerol random copolymer.

9. The method for preparing high-strength wear-resistant polyethylene fiber according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: screening ultra-high molecular weight polyethylene powder and mixing it with a solvent, adding a crosslinking agent, a peroxide, a lubricant and an antioxidant, and fully stirring at 100-150 DEG C to obtain a suspension; adding the suspension into a barrel of a twin-screw extruder from a main feeding port, feeding a flaky filler, a granular filler and a compatibilizer from a side feeding port, and melt-extruding to obtain a polyethylene non-solution mixture; filtering the polyethylene non-solution mixture and spinning it, and cooling it after spinning to obtain polyethylene gel fibers; extracting the polyethylene gel fibers with an extractant to remove the solvent, and performing heat stretching after drying, and shaping and winding to obtain high-strength wear-resistant polyethylene fibers.

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

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