Stretch-resistant ultra-high molecular weight polyethylene fiber and production equipment thereof

Abstract

The invention relates to the technical field of preparation of ultra-high molecular weight polyethylene fibers, and discloses a tensile ultra-high molecular weight polyethylene fiber and production equipment thereof, the tensile ultra-high molecular weight polyethylene fiber comprises a matrix material: 92.1-96.0 parts of ultra-high molecular weight polyethylene; the core composite lubricant is of a three-stage core-shell structure and sequentially comprises a nano sulfur dioxide carrier, an amino functionalized ionic liquid lubricating layer and an aminated carbon nanotube reinforcing layer from inside to outside, and the total size of the three-stage core-shell structure is 50 + / -5 nm; functional aids: 0.9 to 1.9 parts of a gradient regulation and control aid and 0.1 to 0.3 part of an antioxidant; under the action of the core composite lubricant, in combination with a targeted supplement technology and a pulsating pressure field, a form with high core lubrication degree and low surface lubrication degree can be formed in an ultra-high molecular weight polyethylene melt, and the lubrication degree and the fiber strength in the preparation of the ultra-high molecular weight polyethylene fiber are considered; the preparation difficulty is effectively reduced; meanwhile, the tensile property of the fiber is conveniently improved.

Description

Technical Field

[0001] This invention relates to the field of ultra-high molecular weight polyethylene fiber preparation technology, and in particular to a tensile-resistant ultra-high molecular weight polyethylene fiber and its production equipment. Background Technology

[0002] Ultra-high molecular weight polyethylene fiber, abbreviated as UHMWPEF, also known as high-strength, high-modulus polyethylene fiber, is a fiber spun from polyethylene with a molecular weight of 1 million to 5 million. It is currently the fiber with the highest specific strength and specific modulus in the world; its specific strength is more than ten times that of steel wire of the same cross-section, and its specific modulus is second only to high-grade carbon fiber. It has a low density, can float on water, and also features low elongation at break, high breaking energy, outstanding impact and cut resistance, resistance to ultraviolet radiation, chemical corrosion resistance, and good abrasion resistance. Ultra-high molecular weight polyethylene fiber is typically produced using solution spinning, melt spinning, or wet spinning methods, and is widely used in military, aerospace, medical, and sporting goods industries.

[0003] However, due to its extremely high viscosity, ultra-high molecular weight polyethylene (UHMWPE) melts can lead to difficulties in extrusion processing and high energy consumption during fiber preparation. Furthermore, due to its poor flowability and strong shear force, it results in poor fiber forming quality and low tensile strength. To adjust the flowability of UHMWPE melts, existing technologies typically involve adding lubricants. However, excessive lubricant can affect fiber strength, while insufficient or uneven distribution can lead to agglomeration, making it difficult to achieve the required flowability and still affecting fiber production. This presents a critical contradiction in UHMWPE fiber processing: the need for high flowability and the preservation of fiber strength are difficult to achieve simultaneously. Summary of the Invention

[0004] The technical problem to be solved by this invention is that the existing technology usually adjusts the melt flowability of ultra-high molecular weight polyethylene by adding lubricant. However, it faces the problem that too much lubricant reduces strength, while insufficient lubricant or agglomeration makes it difficult to meet the flowability requirements. This creates a key contradiction between the need for high flowability and the retention of fiber strength. To address this, we propose a tensile-resistant ultra-high molecular weight polyethylene fiber and its production equipment.

[0005] To achieve the above objectives, this application adopts the following technical solution: a tensile-resistant ultra-high molecular weight polyethylene fiber, comprising: matrix material: 92.1-96.0 parts of ultra-high molecular weight polyethylene;

[0006] The core composite lubricant comprises 3.3-6.0 parts, wherein the core composite lubricant has a three-level core-shell structure, consisting of a nano-sulfur dioxide carrier, an amino-functionalized ionic liquid lubricating layer, and an amino-functionalized carbon nanotube reinforcing layer from the inside out, and the total size of the three-level core-shell structure is 50±5nm.

[0007] Functional additives: 0.9-1.9 parts of gradient regulation additive, 0.1-0.3 parts of antioxidant;

[0008] The method for preparing tensile-resistant ultra-high molecular weight polyethylene fibers includes the following steps:

[0009] S1. Preparation of a three-level core-shell structured composite lubricant;

[0010] S2. Premix the matrix material, 50%-60% of the core composite lubricant, gradient control agent, and antioxidant to obtain a premixed material.

[0011] S3. The premixed material is fed into the first stage of a two-stage screw extruder for low-temperature mixing;

[0012] S4. The remaining 40%-50% of the core composite lubricant is injected into the second stage of the two-stage screw extruder through the lubricant directional replenishment component. At the same time, a pulsating pressure field is applied to perform high-temperature and high-speed shearing to form a gradient distribution melt with high concentration in the core and low concentration on the surface.

[0013] S5. Ultra-high molecular weight polyethylene melt is extruded through a spinneret at the outlet of a two-stage screw extruder, and then stretched and shaped to form ultra-high molecular weight polyethylene.

[0014] The nano-sulfur dioxide carrier has a particle size of 30-40 nm and a specific surface area of ​​[missing information]. It accounts for 13.9%-14.3% of the total mass of the core composite lubricant.

[0015] Preferably, the alkyl chain length of the amino-functionalized ionic liquid is C12-C18, the anion is a bis(trifluoromethanesulfonyl)imide group, and the solubility parameter difference between the amino-functionalized ionic liquid and ultra-high molecular weight polyethylene ranges from [value missing]. The amino-functionalized ionic liquid accounts for 74.6%-77.8% of the total mass of the core composite lubricant;

[0016] The aspect ratio of the aminated carbon nanotubes is 50-100, and the amino content is [missing information]. It accounts for 4.8%-8.3% of the total mass of the core composite lubricant.

[0017] Preferably, the preparation process of the three-level core-shell structure core composite lubricant is as follows:

[0018] S11. Place the nano-sulfur dioxide in a vacuum oven and dry it at 120°C for 4 hours to remove the surface adsorbed water.

[0019] S12. Place the dried nano-sulfur dioxide into the atomic layer deposition reaction chamber, heat it to 80-100℃, introduce the aminosilane precursor, and adsorb for 10-15 seconds.

[0020] S13. Purge with inert gas for 30-40 seconds to remove unadsorbed aminosilane precursors;

[0021] S14. Simultaneously introduce amino-functionalized ionic liquid monomer and amino-functionalized carbon nanotubes, and react for 20-25 seconds.

[0022] S15. Repeat steps S12-S14 3-5 times, then vacuum dry at 80℃ for 2 hours to obtain a three-level core-shell structured composite lubricant.

[0023] Preferably, the molecular weight of the ultra-high molecular weight polyethylene is [missing value]. The particle size is 50-100μm;

[0024] The gradient-regulating agent is polyolefin wax-grafted nano-calcium carbonate, wherein the nano-calcium carbonate particle size is 10-20 nm, the polyolefin wax grafting rate is 5%-8%, and the difference in solubility parameters between it and ultra-high molecular weight polyethylene fiber ranges from [value missing]. ;

[0025] The antioxidant is a hindered phenolic antioxidant, specifically antioxidant 1010.

[0026] Preferably, the production equipment for tensile-resistant ultra-high molecular weight polyethylene fiber includes a two-stage screw extruder, which comprises a first stage screw extruder and a second stage screw extruder. The first stage screw extruder has a first screw installed inside, which is used to perform low-temperature mixing of the premixed material inside the first stage screw extruder. A feed assembly is provided between the first stage and the second stage screw extruder, and a lubricant directional replenishment assembly is installed inside the feed assembly. The lubricant directional replenishment assembly is used to inject the remaining 40%-50% of the core composite lubricant into the core of the second stage screw extruder, and at the same time apply a pulsating pressure field to the second stage screw extruder. The second stage screw extruder is used to perform high-temperature and high-speed shearing on the material entering its interior through the feed assembly, forming a gradient distribution melt with high concentration in the core and low concentration on the surface.

[0027] Preferably, the second screw is installed inside the second stage of the screw extruder, and a third screw is coaxially arranged at the end of the second screw. The screw groove depth of the second screw gradually becomes shallower, and the screw groove density of the second screw gradually increases.

[0028] Preferably, the top of the first stage of the screw extruder is equipped with a raw material feeding mechanism, which is used to premix the matrix material, 50%-60% of the core composite lubricant, gradient control agent, and antioxidant, and feed the premixed material into the first stage of the screw extruder. The top of the two-stage screw extruder is equipped with a lubricant holding chamber, which is used to store the remaining 40%-50% of the core composite lubricant and to selectively feed it into the second stage of the screw extruder through a lubricant directional replenishment component.

[0029] Preferably, the lubricant directional replenishment assembly includes a driven roller and a transmission roller. The driven roller is rotatably connected to the inside of the lubricant holding chamber, and the transmission roller is fixedly connected to the end of the first screw away from the second screw. A spiral blade is fixedly connected to the end of the transmission roller. A feeding belt is supported on the outer circumference of the driven roller and the transmission roller. A plurality of feeding ports are installed at equal intervals inside the feeding belt, and the number of feeding ports is odd.

[0030] Preferably, the opening of the feeding port faces the outer peripheral surface of the feeding belt, and the bulge of the feeding port faces the inner peripheral surface of the feeding belt. When the transmission roller drives the feeding belt to rotate, the pushing action of the bulges of each feeding port can cause the transmission roller and the second screw and the third screw to reciprocate up and down, thereby forming a pulsating pressure field inside the second stage of the screw extruder.

[0031] Preferably, the feeding assembly includes a partition structure, and a discharge chamber is coaxially arranged inside the partition structure. The opening of the discharge chamber faces the second stage of the screw extruder, and the shape of the discharge chamber is gradually expanding. Several conveying channels are arranged in a ring array on the side of the discharge chamber. The conveying channels are used to convey the material inside the first stage of the screw extruder into the second stage of the screw extruder. A support mechanism is installed on the back of the partition structure. The support mechanism is used to support the drive roller and the first screw.

[0032] The technical effects and advantages of this invention are as follows:

[0033] This invention innovatively achieves a gradient distribution of lubricant with a high core and low surface level within the melt, significantly reducing melt viscosity. This results in a substantial decrease in extrusion pressure and energy consumption, while also preventing damage to the molecular chains from strong shearing, thus ensuring the integrity of the ultra-high molecular weight polyethylene (UHMWPE) molecular chains. Regarding fiber performance improvement, the low surface lubrication reduces the weakening of molecular chain bonds by the lubricant, and the gradient-regulating agent fills the surface gaps, improving surface density and hardness. Simultaneously, the aminated carbon nanotube reinforcement layer of the core composite lubricant forms a synergistic network in the core, effectively enhancing the fiber's tensile strength. This allows the fiber to maintain excellent mechanical properties while possessing good processing flowability. Furthermore, the accompanying production equipment enables precise lubricant dispensing, ensuring stable production processes. Attached Figure Description

[0034] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts:

[0035] Figure 1 This is a schematic cross-sectional view of the production equipment for the tensile-resistant ultra-high molecular weight polyethylene fiber of the present invention.

[0036] Figure 2 This is a three-dimensional structural diagram of the production equipment for the tensile-resistant ultra-high molecular weight polyethylene fiber of the present invention.

[0037] Figure 3 This is a three-dimensional structural diagram of the internal structure of the two-stage screw extruder of the present invention;

[0038] Figure 4 This is a three-dimensional structural diagram of the first screw and the second screw portion of the present invention;

[0039] Figure 5 This is a cross-sectional structural diagram of the lubricant directional replenishment component and the feed conveying component of the present invention;

[0040] Figure 6 This is a three-dimensional structural diagram of the feeding belt and feeding port of the present invention;

[0041] Figure 7 This is a schematic cross-sectional view of the discharge chamber and the spiral blade section of the present invention.

[0042] Figure 8 This is a three-dimensional structural diagram of the feed assembly part of the present invention.

[0043] Legend: 1. Two-stage screw extruder; 2. First screw; 3. Second screw; 4. Third screw; 5. Raw material feeding mechanism; 6. Lubricant holding chamber; 7. Lubricant directional replenishment assembly; 8. Feeding assembly; 701. Driven roller; 702. Drive roller; 703. Feeding belt; 704. Feeding port; 705. Discharge chamber; 706. Spiral blade; 801. Separation structure; 802. Material conveying channel; 803. Support mechanism. Detailed Implementation

[0044] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0045] Example 1:

[0046] Matrix material: 95.0 parts of ultra-high molecular weight polyethylene, with a molecular weight of [missing information]. The particle size is 80 μm;

[0047] Core composite lubricant: 3.5 parts, including a nano-silica carrier with a particle size of 35 nm, accounting for 14.0% of the total mass of the core composite lubricant. Amino-functionalized ionic liquid with an alkyl chain length of C14 and an anion of bis(trifluoromethanesulfonyl)imide. The difference in solubility parameters between it and ultra-high molecular weight polyethylene is [value missing]. This accounts for 76.0% of the total mass of the core composite lubricant. Aminated carbon nanotubes: aspect ratio 60, amino content... It accounts for 6% of the total mass of the core composite lubricant. The total size of the three-level core-shell structure is 50 nm.

[0048] Functional additives: including gradient regulation additives: 1.0 part. These are polyolefin wax-grafted nano-calcium carbonate, with a nano-calcium carbonate particle size of 15 nm and a polyolefin wax grafting rate of 6%. The difference in solubility parameters between this additive and ultra-high molecular weight polyethylene is [value missing]. Antioxidant: 0.2 parts, specifically hindered phenolic antioxidant 1010.

[0049] Preparation steps:

[0050] First, a three-level core-shell structured composite lubricant is prepared, including the following steps:

[0051] The first step is to place the nano-silica in a vacuum oven and dry it at 120°C for 4 hours.

[0052] The second step involves placing the dried nano-silica into the atomic layer deposition reaction chamber, heating it to 85°C, and introducing the aminopropyltrimethoxysilane precursor for 12 seconds of adsorption.

[0053] The third step is to purge with high-purity nitrogen for 35 seconds.

[0054] Fourth step: Simultaneously introduce a dispersion of amino-functionalized ionic liquid monomer and amino-functionalized carbon nanotubes, and react for 22 seconds.

[0055] The fifth step involves repeating the first four steps four times, followed by vacuum drying at 80°C for 2 hours to obtain a three-stage core-shell structure composite lubricant.

[0056] Secondly, premixing is carried out: 95.0 parts of ultra-high molecular weight polyethylene, 1.93 parts (accounting for 55% of the total lubricant) of core composite lubricant, 1.0 part of gradient regulation agent and 0.2 parts of antioxidant 1010 are premixed in a high-speed mixer for 15 minutes to obtain premixed material.

[0057] Next, low-temperature mixing is carried out: the premixed material is fed into the first stage of a two-stage screw extruder and mixed at 135°C and 50 rpm.

[0058] Then, directional replenishment and melt shearing are performed: the remaining 1.57 parts (accounting for 45% of the total lubricant) of core composite lubricant are injected into the second stage of the two-stage screw extruder through the lubricant directional replenishment component, while a pulsating pressure field is applied to perform high-temperature and high-speed shearing to form a gradient distribution melt with high concentration in the core and low concentration on the surface.

[0059] Finally, spinning and post-processing are carried out: the ultra-high molecular weight polyethylene melt is extruded through the spinneret at the outlet of the two-stage screw extruder, and then subjected to 30 times super-stretching and setting to finally form tensile-resistant ultra-high molecular weight polyethylene fibers.

[0060] This embodiment employs a high matrix resin content (95.0 parts) and a moderate amount of composite lubricant (3.5 parts), wherein the ionic liquid has a short alkyl chain (C14) and a low aspect ratio of carbon nanotubes (60), focusing on ensuring the absolute mechanical strength of the fiber. The fiber produced by this formulation and process exhibits extremely high tensile strength and modulus, with a breaking strength ≥35cN / dtex, but its processing window is relatively narrow, making it more suitable for applications with stringent requirements for fiber performance limits, such as bulletproof vests and heavy-duty cables.

[0061] Example 2:

[0062] Matrix material: Ultra-high molecular weight polyethylene: 92.5 parts, with a molecular weight of The particle size is 60μm.

[0063] Core composite lubricant: 6.0 parts, including nano-silica carrier: particle size 38nm, accounting for 14.2% of the total mass of the core composite lubricant. Amino-functionalized ionic liquid: alkyl chain length C18, anion is bis(trifluoromethanesulfonyl)imide, and its solubility parameter difference with ultra-high molecular weight polyethylene is [value missing]. The core composite lubricant comprises 77.5% of its total mass. Aminated carbon nanotubes, with an aspect ratio of 100 and an amino content of 1.5 wt%, account for 8.3% of the total mass of the core composite lubricant. The total size of the tertiary core-shell structure is 53 nm.

[0064] Functional additives include a gradient regulating agent: 1.8 parts. This agent is polyolefin wax-grafted nano-calcium carbonate, with a nano-calcium carbonate particle size of 12 nm and a polyolefin wax grafting rate of 7.5%. The difference in solubility parameters between this agent and ultra-high molecular weight polyethylene is [value missing]. Antioxidant: 0.3 parts. Specifically, hindered phenolic antioxidant 1010.

[0065] Preparation steps:

[0066] First, the preparation of a three-level core-shell structured composite lubricant includes the following steps:

[0067] The first step is to place the nano-silica in a vacuum oven and dry it at 120°C for 4 hours.

[0068] The second step involves placing the dried nano-silica into the atomic layer deposition reaction chamber, heating it to 95°C, and introducing the aminopropyltriethoxysilane precursor for adsorption for 15 seconds.

[0069] The third step is to purge with high-purity argon gas for 40 seconds.

[0070] Fourth step: Simultaneously introduce a dispersion of amino-functionalized ionic liquid monomer and amino-functionalized carbon nanotubes, and react for 25 seconds.

[0071] The fifth step involves repeating the first four steps five times, followed by vacuum drying at 80°C for 2 hours to obtain a three-stage core-shell structured composite lubricant.

[0072] Secondly, premixing is carried out: 92.5 parts of ultra-high molecular weight polyethylene, 3.0 parts (accounting for 50% of the total lubricant) of core composite lubricant, 1.8 parts of gradient regulation additive and 0.3 parts of antioxidant 1010 are premixed in a high-speed mixer for 18 minutes to obtain premixed material.

[0073] Next, low-temperature mixing is carried out: the premixed material is fed into the first stage of a two-stage screw extruder and mixed at 130°C and 60 rpm.

[0074] Then, directional replenishment and melt shearing are performed: the remaining 3.0 parts (accounting for 50% of the total lubricant) of core composite lubricant are injected into the second stage of the two-stage screw extruder through the lubricant directional replenishment component, while a pulsating pressure field is applied to perform high-temperature and high-speed shearing to form a gradient distribution melt with high concentration in the core and low concentration on the surface.

[0075] Finally, spinning and post-processing are carried out: the ultra-high molecular weight polyethylene melt is extruded through the spinneret at the outlet of the two-stage screw extruder, and then subjected to 35 times super-stretching and setting to finally form tensile-resistant ultra-high molecular weight polyethylene fibers.

[0076] This embodiment increases the amount of composite lubricant (6.0 parts) and employs ionic liquids with longer alkyl chains (C18) and carbon nanotubes with a higher aspect ratio (100), while also increasing the amount of gradient-regulating additives. This results in excellent melt flowability and lubricity of the fiber during processing, and a more pronounced concentration gradient structure. Ultimately, the fiber maintains good strength, with a breaking strength of approximately 30 cN / dtex, exhibiting excellent fatigue resistance and flexibility. Its higher elongation at break makes it more suitable for applications requiring repeated dynamic loads, such as high-end fishing lines and flexible composite reinforcements.

[0077] Comparative example:

[0078] Traditional techniques for improving the processing flowability of ultra-high molecular weight polyethylene (UHMWPE) typically employ a strategy of physically blending lubricants with the matrix resin. The core idea is to achieve uniform dispersion of the lubricant in the melt, rather than forming a gradient structure. The formulation and preparation method are as follows:

[0079] Matrix material: Ultra-high molecular weight polyethylene: 95.0 parts, molecular weight is The particle size is 80μm.

[0080] Lubricant system: 4.5 parts.

[0081] Ordinary paraffin oil: 4.0 parts; Paraffin oil is a low molecular weight lubricant commonly used in the processing of ultra-high molecular weight polyethylene. It has good compatibility with polyethylene and can effectively penetrate between macromolecular chains to reduce friction and viscosity, but it does not have special interface enhancement function.

[0082] Unfunctionalized multi-walled carbon nanotubes: 0.5 parts, as a reinforcing material.

[0083] Functional additives, antioxidants: 0.2 parts, specifically antioxidant 1010, used to provide thermal and oxygen stability.

[0084] The preparation method is as follows:

[0085] First, premix: Add 95.0 parts of ultra-high molecular weight polyethylene, 4.0 parts of ordinary paraffin oil, 0.5 parts of unfunctionalized multi-walled carbon nanotubes and 0.2 parts of antioxidant 1010 to a high-speed mixer at once and mix for 20 minutes to ensure that all components are mixed evenly.

[0086] Next, melt blending is carried out: all the above premixed materials are fed into a conventional single-screw extruder and melt blended and granulated at a temperature of 180-200℃.

[0087] Next, melt spinning is carried out: the prepared granules are fed into a spinning extruder and extruded through a spinneret to form nascent fibers.

[0088] Finally, post-stretching and shaping are performed: the nascent fibers undergo 25 times super-stretching in a hot box to form ultra-high molecular weight polyethylene fibers.

[0089] Compared to the comparative example, the technical solution of this invention constructs a three-level core-shell structure for the core composite lubricant and combines it with a two-step directional feeding process, actively forming a precise gradient distribution structure within the fiber with a high concentration of lubricant in the core and a low concentration on the surface. During processing, the lubricant enriched in the core significantly reduces the bulk viscosity of the melt and improves processing fluidity, while the surface layer, maintaining a high polymer concentration, preserves melt strength, effectively suppressing outlet expansion and melt fracture, making the spinning process more stable. In terms of final performance, the near-pure, high-strength surface layer directly bears most of the tensile stress, avoiding premature failure caused by uniformly dispersed lubricant acting as a stress defect point. Simultaneously, through the strong interfacial bonding between the aminated carbon nanotubes in the core-shell structure and the matrix, efficient stress transfer and reinforcement are achieved. This solution significantly improves the demanding processing performance of ultra-high molecular weight polyethylene without sacrificing its mechanical properties. Instead, it synergistically enhances the final tensile strength, modulus, and structural density of the fiber, achieving integrated optimization of processability and product performance, and overcoming the inherent contradiction between processability and performance in traditional technologies.

[0090] Please see Figure 1 and Figure 2 As shown, the production equipment for tensile-resistant ultra-high molecular weight polyethylene (UHMWPE) fibers includes a two-stage screw extruder 1. The two-stage screw extruder 1 includes a first stage screw extruder and a second stage screw extruder. A raw material feeding mechanism 5 is installed at the top of the first stage screw extruder. The raw material feeding mechanism 5 is used to premix the matrix material, 50%-60% of the core composite lubricant, gradient control agent, and antioxidant, and feed the premixed material into the first stage screw extruder. A first screw 2 is installed inside the first stage screw extruder. The first screw 2 is used to perform low-temperature mixing of the premixed material inside the first stage screw extruder. Through low-speed shearing of the screw, the lubricant in the premixed material is further uniformly dispersed to form UHMWPE material containing a low concentration of lubricant. This is used to complete the initial plasticization and dispersion of the raw material, reserve concentration adjustment space for the gradient control of the second stage, and at the same time ensure the integrity of the UHMWPE molecular chain through the low-temperature environment.

[0091] A feed assembly 8 is installed between the first and second stages of the screw extruder, and a lubricant directional replenishment assembly 7 is installed inside the feed assembly 8. The remaining 40%-50% of the core composite lubricant is precisely injected into the melt core of the second stage through the lubricant directional replenishment assembly 7. Combined with the high temperature of 190-210℃ inside the second stage of the screw extruder, the high-speed shearing of the second screw 3 and the third screw 4 at 200-250 r / min, and the pulsating pressure field formed by the lubricant directional replenishment assembly 7 in the second stage of the screw extruder, the lubricant concentration in the core is rapidly increased. At the same time, the gradient control additive migrates to the surface due to differences in oleophilicity and density, forcing the surface lubricant to move towards the core, ultimately forming a gradient melt with high lubrication in the core and low lubrication on the surface. The three-level core-shell structure of the core composite lubricant plays a synergistic role in this process: the ionic liquid lubricating layer reduces the viscosity of the core melt and improves fluidity; the aminated carbon nanotube reinforcing layer forms a network in the core to inhibit molecular chain slippage; and the nano-sulfur dioxide carrier prevents lubricant agglomeration.

[0092] By achieving a gradient distribution of high lubricant in the core and low lubricant in the surface layer within the ultra-high molecular weight polyethylene melt through directional feeding and flow field control, the processing challenges caused by high melt viscosity and the strength reduction caused by uniform lubricant addition can be precisely resolved. High lubrication in the core can significantly reduce melt viscosity, improve fluidity, reduce extrusion pressure and energy consumption, and avoid molecular chain degradation caused by strong shear. Low lubrication in the surface layer reduces the weakening of molecular chain bonding by the lubricant. Combined with gradient control additives to fill surface gaps, it improves surface density and hardness. At the same time, the reinforcing layer of the core composite lubricant forms a synergistic network in the core, further ensuring the tensile strength of the fiber. Ultimately, this achieves a balance between processing fluidity and fiber strength, improving production stability and product performance consistency.

[0093] Please see Figure 3 , Figure 4 As shown, a second screw 3 is installed inside the second stage of the screw extruder, and a third screw 4 is coaxially arranged at the end of the second screw 3. The screw groove depth of the second screw 3 gradually decreases, and the screw groove density of the second screw 3 gradually increases. The second screw 3 corresponds to the lubricant concentration gradient formation stage. Its screw groove depth gradually decreases and its screw groove density gradually increases. It can enhance the pressure control and shearing effect on the melt through the optimization of the flow channel structure, providing mechanical support for the formation of the lubricant gradient distribution. The decrease in screw groove depth can make the pressure of the melt gradually increase during the forward movement. The core material provided by the lubricant directional replenishment component 7 promotes the accumulation of the replenished core composite lubricant in the core of the melt. The increase in screw groove density increases the shearing frequency and intensity of the screw on the melt, accelerates the formation and stabilization of the high concentration of lubricant content in the core and the low concentration of lubricant content in the surface layer of the ultra-high molecular weight polyethylene melt inside the second stage of the screw extruder, and thus ensures the synergistic optimization of melt processing fluidity and fiber strength.

[0094] Please see Figure 5 , Figure 6 , Figure 7 As shown, a lubricant storage chamber 6 is installed at the top of the two-stage screw extruder 1. The lubricant storage chamber 6 is used to store the remaining 40%-50% of the core composite lubricant and to selectively add it into the second stage of the screw extruder through a lubricant directional replenishment component 7. The lubricant directional replenishment component 7 includes a driven roller 701 and a drive roller 702. The driven roller 701 is rotatably connected to the inside of the lubricant storage chamber 6, and the drive roller 702 is fixedly connected to the end of the first screw 2 away from the second screw 3. A spiral blade 706 is fixedly connected to the end of the drive roller 702. A feeding belt 703 supports the outer circumference of the driven roller 701 and the drive roller 702. A plurality of feeding ports 704 are installed at equal intervals inside the feeding belt 703. The opening of 704 faces the outer peripheral surface of the feeding belt 703, the opening of the discharge chamber 705 faces the second stage of the screw extruder, and the shape of the discharge chamber 705 is gradually expanding. The bulge of the feeding port 704 faces the inner peripheral surface of the feeding belt 703. The number of feeding ports 704 is odd, so that when one of the driven roller 701 and the drive roller 702 is supported at the bulge of the feeding port 704, the other side is just located in the gap of the bulge. The two alternate to prevent the feeding belt 703 from being too tight or too loose. When the drive roller 702 drives the feeding belt 703 to rotate, the pushing action of the bulges of each feeding port 704 can form a pulsating pressure field inside the second stage of the screw extruder with the drive roller 702, the second screw 3, and the third screw 4.

[0095] The outer surface of the drive roller 702, the inner circumference of the feeding belt 703, and the surface of the bulge of the feeding port 704 are all provided with anti-slip texture. When the drive roller 702 rotates with the second screw 3, it drives the feeding belt 703 to rotate around the driven roller 701 and the drive roller 702. When the opening of the feeding port 704 reaches the inside of the lubricant holding cavity 6, the core composite lubricant inside the lubricant holding cavity 6 can be placed inside the feeding port 704. When it rotates to the inside of the discharge cavity 705 and the opening is facing down, the core composite lubricant inside will fall into the inside of the discharge cavity 705 under the action of gravity. Under the action of the inclined surface at the bottom of the discharge cavity 705, it slides towards the opening. When it slides to the spiral blade 706, it will be sent to the end of the second screw 3, that is, the core position of the ultra-high molecular weight polyethylene melt, under the conveying action of the spiral blade 706.

[0096] This structure can precisely replenish the core composite lubricant inside the lubricant holding chamber 6 to the core of the second-stage melt. Precise replenishment to the core directly increases the lubricant concentration in the core, quickly establishes a gradient difference, and reduces the probability of lubricant migration to the surface. At the same time, the transmission roller 702 dynamically matches the replenishment amount with the rotational speed of the second screw 3 and the third screw 4, ensuring that the lubricant concentration in the core remains within the target range when the rotational speed of the second screw 3 and the third screw 4 changes. This avoids insufficient or excessive lubrication in the core due to rotational speed fluctuations, enhances the stability and accuracy of the lubrication gradient distribution, further ensures high core fluidity to reduce extrusion energy consumption and pressure, and avoids the impact of insufficient or excessive core lubrication on fiber strength. This achieves dynamic adaptation between the processing process and product performance, improving production stability and consistency of fiber batch performance.

[0097] When the bulge of the feed port 704 moves to directly below the drive roller 702, it pushes the drive roller 702, causing the second screw 3 and the third screw 4 to move upward. When the gap between each feed port 704 is aligned with directly below the drive roller 702, the drive roller 702, the second screw 3, and the third screw 4 will move downward under the action of gravity. Through the up-and-down reciprocating motion of the drive roller 702 and the second screw 3 and the third screw 4, a pulsating pressure field is formed inside the second stage of the screw extruder. Due to the transmission of the drive roller 702, the frequency of this pulsating pressure field is dynamically matched with the rotational speed of the second screw 3 and the third screw 4.

[0098] The periodic changes in pulsating pressure can drive the surface lubricant of the melt to migrate towards the core, further enhancing the concentration difference between the high lubrication in the core and the low lubrication on the surface. At the same time, it promotes the uniform dispersion of the core composite lubricant in the core and avoids agglomeration. The matching of the frequency of the pulsating pressure field with the rotational speed of the second screw 3 and the third screw 4 ensures that the pressure regulation and melt delivery speed are synchronized, preventing the gradient distribution from becoming unbalanced due to changes in rotational speed. This facilitates the effective improvement of the stability and uniformity of the lubrication gradient, reduces melt viscosity to reduce extrusion energy consumption and pressure, and at the same time ensures the fluidity of the core and the strength of the surface of the ultra-high polyethylene melt, avoiding excessive slippage or degradation of molecular chains, and ultimately improving the fiber forming quality and batch performance consistency.

[0099] The feeding assembly 8 includes a partition structure 801. A discharge chamber 705 is coaxially arranged inside the partition structure 801. Several conveying channels 802 are arranged in a ring array on the sides of the discharge chamber 705. The conveying channels 802 are used to convey the material inside the first stage of the screw extruder into the second stage of the screw extruder. A support mechanism 803 is installed on the back of the partition structure 801. The support mechanism 803 is used to support the drive roller 702 and the first screw 2.

[0100] Working principle: The matrix material, 50%-60% of the core composite lubricant, gradient control agent, and antioxidant are premixed inside the raw material feeding mechanism 5. The premixing temperature is 25-30℃, the rotation speed is 30-50 r / min, and the time is 10-15 min to obtain the premixed material. The premixed material is fed into the two-stage screw extruder 1 through the screw conveyor at the bottom of the raw material feeding mechanism 5. At this time, the material is in the first stage of the screw extruder, and its internal temperature is maintained at 140℃-150℃. The rotation speed of the first screw 2 is 80-100 r / min to complete the initial dispersion of the material and avoid premature melting and degradation of the matrix material. The purpose of this stage is to allow the core composite lubricant to be uniformly attached to the surface of the polyethylene particles to avoid initial agglomeration, and at the same time reserve space for the gradient control of the second stage.

[0101] After initial dispersion in the first stage of the screw extruder, the material enters the second stage of the screw extruder through the feeding channel 802. At the same time, the remaining 40%-50% of the core composite lubricant is injected into the core melt region of the second stage of the screw extruder through the lubricant directional replenishment component 7, which rapidly increases the core melt concentration of the material, forms an initial gradient difference, and reduces the control load of the subsequent pulsating pressure field. Meanwhile, through the pushing action of the bulges at each feeding port 704, a pulsating pressure field is formed inside the second stage of the screw extruder by the drive roller 702 and the second screw 3 and the third screw 4. At this time, the second screw 3 and the third screw 4 maintain a rotation speed of 200-250 r / min, subjecting the melt to high-temperature and high-speed shearing, forming a gradient distribution melt with high core concentration and low surface concentration. Finally, the ultra-high molecular weight polyethylene melt is extruded through the spinneret at the end of the second stage of the screw extruder, and then stretched and shaped to form ultra-high molecular weight polyethylene.

[0102] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A tensile-resistant ultra-high molecular weight polyethylene fiber, characterized in that, include Matrix material: 92.1-96.0 parts of ultra-high molecular weight polyethylene; The core composite lubricant comprises 3.3-6.0 parts, wherein the core composite lubricant has a three-level core-shell structure, consisting of a nano-sulfur dioxide carrier, an amino-functionalized ionic liquid lubricating layer, and an amino-functionalized carbon nanotube reinforcing layer from the inside out, and the total size of the three-level core-shell structure is 50±5nm. Functional additives: 0.9-1.9 parts of gradient regulation additive, 0.1-0.3 parts of antioxidant; The method for preparing tensile-resistant ultra-high molecular weight polyethylene fibers includes the following steps: S1. Preparation of a three-level core-shell structured composite lubricant; S2. Premix the matrix material, 50%-60% of the core composite lubricant, gradient control agent, and antioxidant to obtain a premixed material. S3. The premixed material is fed into the first stage of a two-stage screw extruder for low-temperature mixing; S4. The remaining 40%-50% of the core composite lubricant is injected into the second stage of the two-stage screw extruder through the lubricant directional replenishment component. At the same time, a pulsating pressure field is applied to perform high-temperature and high-speed shearing to form a gradient distribution melt with high concentration in the core and low concentration on the surface. S5. Ultra-high molecular weight polyethylene melt is extruded through the spinneret at the outlet of a two-stage screw extruder, and then stretched and shaped to form ultra-high molecular weight polyethylene.

2. The tensile-resistant ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that: The nano-sulfur dioxide carrier has a particle size of 30-40 nm and a specific surface area of ​​[missing information]. This accounts for 13.9%-14.3% of the total mass of the core composite lubricant; The amino-functionalized ionic liquid has an alkyl chain length of C12-C18, and its anion is a bis(trifluoromethanesulfonyl)imide group. The solubility parameter difference between the amino-functionalized ionic liquid and ultra-high molecular weight polyethylene ranges from [value missing]. The amino-functionalized ionic liquid accounts for 74.6%-77.8% of the total mass of the core composite lubricant; The aspect ratio of the aminated carbon nanotubes is 50-100, and the amino content is [missing information]. It accounts for 4.8%-8.3% of the total mass of the core composite lubricant.

3. The tensile-resistant ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that: The preparation process of the three-level core-shell structure core composite lubricant is as follows: S11. Place the nano-sulfur dioxide in a vacuum oven and dry it at 120°C for 4 hours to remove the surface adsorbed water. S12. Place the dried nano-sulfur dioxide into the atomic layer deposition reaction chamber, heat it to 80-100℃, introduce the aminosilane precursor, and adsorb for 10-15 seconds. S13. Purge with inert gas for 30-40 seconds to remove unadsorbed aminosilane precursors; S14. Simultaneously introduce amino-functionalized ionic liquid monomer and amino-functionalized carbon nanotubes, and react for 20-25 seconds. S15. Repeat steps S12-S14 3-5 times, then vacuum dry at 80℃ for 2 hours to obtain a three-level core-shell structured composite lubricant.

4. The tensile-resistant ultra-high molecular weight polyethylene fiber according to claim 1, characterized in that: The molecular weight of the ultra-high molecular weight polyethylene is The particle size is 50-100μm; The gradient-regulating agent is polyolefin wax-grafted nano-calcium carbonate, wherein the nano-calcium carbonate particle size is 10-20 nm, the polyolefin wax grafting rate is 5%-8%, and the difference in solubility parameters between it and ultra-high molecular weight polyethylene fiber ranges from [value missing]. ; The antioxidant is a hindered phenolic antioxidant, specifically antioxidant 1010.

5. The production equipment for tensile-resistant ultra-high molecular weight polyethylene fiber according to any one of claims 1-4, characterized in that: The invention includes a two-stage screw extruder, comprising a first stage and a second stage. The first stage has a first screw installed inside, which is used for low-temperature mixing of the premixed material within the first stage. A feed assembly is provided between the first and second stages, and a lubricant directional replenishment assembly is installed inside the feed assembly. This lubricant directional replenishment assembly is used to selectively inject the remaining 40%-50% of the core composite lubricant into the core of the second stage, while simultaneously applying a pulsating pressure field to the second stage. The second stage is used to perform high-temperature, high-speed shearing of the material entering through the feed assembly, forming a gradient melt with high concentration in the core and low concentration on the surface.

6. The production equipment for tensile-resistant ultra-high molecular weight polyethylene fiber according to claim 5, characterized in that: The second stage of the screw extruder is equipped with a second screw, and a third screw is coaxially arranged at the end of the second screw. The screw groove depth of the second screw gradually becomes shallower, and the screw groove density of the second screw gradually increases.

7. The production equipment for tensile-resistant ultra-high molecular weight polyethylene fiber according to claim 5, characterized in that: The top of the first stage of the screw extruder is equipped with a raw material feeding mechanism, which is used to premix the matrix material, 50%-60% of the core composite lubricant, gradient control agent, and antioxidant, and feed the premixed material into the first stage of the screw extruder. The top of the two-stage screw extruder is equipped with a lubricant holding chamber, which is used to store the remaining 40%-50% of the core composite lubricant and to selectively feed it into the second stage of the screw extruder through a lubricant directional replenishment component.

8. The production equipment for tensile-resistant ultra-high molecular weight polyethylene fiber according to claim 5, characterized in that: The lubricant directional replenishment assembly includes a driven roller and a transmission roller. The driven roller is rotatably connected to the inside of the lubricant holding chamber, and the transmission roller is fixedly connected to the end of the first screw away from the second screw. A spiral blade is fixedly connected to the end of the transmission roller. A feeding belt is supported on the outer circumference of the driven roller and the transmission roller. A number of feeding ports are installed at equal intervals inside the feeding belt, and the number of feeding ports is odd.

9. The production equipment for tensile-resistant ultra-high molecular weight polyethylene fiber according to claim 8, characterized in that: The opening of the feeding port faces the outer circumferential surface of the feeding belt, and the bulge of the feeding port faces the inner circumferential surface of the feeding belt. When the transmission roller drives the feeding belt to rotate, the pushing action of the bulges of each feeding port can cause the transmission roller and the second screw and the third screw to reciprocate up and down, thereby forming a pulsating pressure field inside the second stage of the screw extruder.

10. The production equipment for tensile-resistant ultra-high molecular weight polyethylene fiber according to claim 5, characterized in that: The feeding assembly includes a partition structure, and a discharge chamber is coaxially arranged inside the partition structure. The opening of the discharge chamber faces the second stage of the screw extruder, and the shape of the discharge chamber is gradually expanding. Several conveying channels are arranged in a ring array on the side of the discharge chamber. The conveying channels are used to transport the material inside the first stage of the screw extruder into the second stage of the screw extruder. A support mechanism is installed on the back of the partition structure. The support mechanism is used to support the drive roller and the first screw.

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