High-toughening wear-resistant low-noise polyformaldehyde compound and preparation method thereof

Abstract

The invention discloses a high-toughening wear-resistant low-noise polyformaldehyde compound and a preparation method thereof, the compound comprises the following raw material components: copolyformaldehyde, thermoplastic polyurethane and organic silicon mixed resin, and the mass ratio of the copolyformaldehyde to the thermoplastic polyurethane to the organic silicon mixed resin is (74-88): (10-20): (1-5). The thermoplastic polyurethane and the organic silicon mixed resin are added and have a synergistic effect, so that the polyformaldehyde composite material has excellent toughness and wear resistance, and meanwhile, the formaldehyde adsorbent, the antioxidant and an extruder vacuum system jointly act, so that the toughness and wear resistance of the polyformaldehyde composite material are improved, and the service life of the polyformaldehyde composite material is prolonged. And free radicals and unstable small molecules generated in the system can be effectively absorbed and eliminated from the system, and internal defects of the polyformaldehyde mixture are reduced, so that the toughness and wear resistance of the polyformaldehyde compound material are improved, and the noise of the polyformaldehyde compound material is reduced.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a polyoxymethylene composite and its preparation method, and more particularly to a highly toughened, wear-resistant, and low-noise polyoxymethylene composite and its preparation method. Background Technology

[0002] Polyoxymethylene (POM), as a high-performance engineering plastic, possesses outstanding high rigidity, high strength, and inherent self-lubricating properties, demonstrating extremely broad application prospects in many key fields such as automotive manufacturing, industrial machinery and equipment, and electronics. Gears, bearings, and other precision mechanical parts made from wear-modified POM-based materials are also widely used in mechanical engineering and industrial automation. However, existing wear-modified POM materials still have significant shortcomings in performance. Among the most prominent issues are a high coefficient of friction and poor wear resistance, limiting their application to low-speed, low-load conditions. In applications with near-perfect precision requirements, such as aerospace and high-precision instrument manufacturing, and under extreme conditions like high temperature, high pressure, and high load, these wear-modified POM materials not only have a significantly shortened service life but also generate sharp, piercing noise during operation, severely affecting the stability and reliability of equipment. These defects greatly restrict the wider application and promotion of POM materials.

[0003] From the perspective of material preparation process and formulation design, the commonly used wear-resistant polyoxymethylene (POM) products currently on the market generally have problems such as low strength, poor toughness, and high noise. This characteristic means that they can only be used in specific application scenarios with stable operation and light load, and it is difficult to meet the stringent requirements of complex working conditions and diversified fields for the comprehensive performance of materials, thus limiting the application expansion of POM materials in emerging industries and high-end manufacturing fields.

[0004] To overcome the aforementioned problems, researchers in the field of polyoxymethylene (POM) have conducted extensive studies. For example, Chinese patent CN117511119A discloses a high-strength, high-wear-resistant, and low-noise POM alloy and its preparation method. By adding PE-based wear-resistant agents, glass fibers, silicone masterbatches, and lubricating oil, the wear resistance and strength of POM materials are improved. However, the addition of PE-based wear-resistant agents and glass fibers leads to a significant decrease in the toughness of POM materials, with a maximum elongation at break of only 3.1%. Furthermore, the addition of lubricating oil can cause excessive oil film extrusion, resulting in slippage and affecting production efficiency. At the same time, slippage causes POM to remain stagnant in the machine for a long time, leading to material decomposition and ultimately affecting product quality. Chinese patent CN103627135A discloses a high-toughness, high-wear-resistant polyoxymethylene (POM) composite and its preparation method. By adding polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), ethylene propylene diene monomer (EPDM), styrene-butadiene rubber (SBR), and thermoplastic polyurethane, the toughness and wear resistance of the POM material are improved. However, the poor compatibility between the systems in this patent leads to reduced strength and increased noise in the POM composite material. Furthermore, the high cost of raw materials in this patent makes it unsuitable for practical industrial production and application. A similar situation exists in patent CN101885896A. Therefore, developing a POM composite with good toughness, high wear resistance, and low noise, and its preparation method, is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a highly toughened, wear-resistant, and low-noise polyoxymethylene (POM) composite and its preparation method. This application incorporates a thermoplastic polyurethane and an organosilicon mixed resin, which work synergistically to give the POM composite material excellent toughness and wear resistance. Simultaneously, the formaldehyde adsorbent, antioxidant, and extruder vacuum system work together to effectively absorb and eliminate free radicals and unstable small molecules generated in the system, reducing internal defects in the POM mixture, thereby improving the toughness and wear resistance of the POM composite material and reducing its noise.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw material components: copolyoxymethylene, thermoplastic polyurethane, and organosilicon mixed resin, wherein the mass ratio of the copolyoxymethylene, thermoplastic polyurethane, and organosilicon mixed resin is (74-88):(10-20):(1-5).

[0007] Furthermore, the organosilicon mixed resin has a particle size of 30µm, its main chain is an organosilicon structure with a content of 70%, and its side chains are acrylic acid (AC) or vinyl acetate (VA) structures. This organosilicon mixed resin is obtained by the following preparation method: First, a mixture of organosilicon monomers, water, sodium dodecylbenzenesulfonate emulsifier, and potassium persulfate initiator is mixed and reacted at 70-80°C for 3-4 hours to generate an organosilicon seed emulsion. Then, water, sodium dodecylbenzenesulfonate emulsifier, acrylic acid or vinyl acetate monomer, and potassium persulfate initiator are added to the organosilicon seed emulsion. Sodium dodecylbenzenesulfonate emulsifier is added every 1 hour at 75-85°C, and the reaction is carried out for 6-8 hours. After the reaction is completed, the mixture is cooled to below 40°C, the pH is adjusted to 7-8 with ammonia, and a small amount of gel is removed by filtration to obtain a mixed organosilicon resin. The mass ratio of acrylic acid or vinyl acetate monomer, water, sodium dodecylbenzenesulfonate emulsifier, potassium persulfate initiator, and organosilicon monomer is (4-6):(60-100):(15-25):(1.5-4):(5-10).

[0008] Specifically, firstly, organosilicon monomers are prepared into organosilicon seed emulsions to form "seed cores." Then, another monomer, either acrylic acid or vinyl acetate, is added to the system. The acrylic acid or vinyl acetate monomers are adsorbed onto the surface of the "seed core" and polymerized, ultimately forming a core-shell structure organosilicon mixed resin with organosilicon as the core and acrylic acid or vinyl acetate as the shell. When the organosilicon resin is blended with a polyoxymethylene (POM) matrix, the silicon-oxygen bond framework of the organosilicon mixed resin constitutes the core phase. The organic functional groups in the shell, such as carboxyl and ester groups, have good compatibility with the POM matrix. The organosilicon mixed resin is uniformly distributed in the POM continuous phase as a dispersed phase, forming an "island structure." When the POM composite material is subjected to external forces, this "island structure"... The dispersed phase of the silicone resin in the core-shell structure can act as a source of stress concentration points. By dispersing stress concentration points and absorbing impact energy, the "island structure" effectively hinders crack propagation, causing the polyoxymethylene (POM) composite material to consume more energy during fracture, thus significantly improving the toughness of the POM composite material. At the same time, when the POM composite material is subjected to external friction, the low surface properties (such as hydrophobicity) of the silicone resin can form a lubricating layer at the friction interface, reducing the friction coefficient of the POM composite material, thereby improving the wear resistance of the POM composite material. Moreover, the three-dimensional network structure in the silicone resin core-shell structure can restrict the sliding of the POM molecular chains, reduce ploughing wear and wear debris generation, thereby further improving the wear resistance of the POM composite material and reducing the noise of the POM composite material.

[0009] Furthermore, the melt index of the copolymerized formaldehyde ranges from 5 to 9 g / 10 min, and the test conditions for the melt index are 190℃ / 2.16 kg.

[0010] Furthermore, the polyoxymethylene compound also includes a lubricant.

[0011] Furthermore, the polyoxymethylene compound also includes a release agent.

[0012] Furthermore, the polyoxymethylene compound also includes a formaldehyde adsorbent.

[0013] Furthermore, the polyoxymethylene compound also includes antioxidants.

[0014] Furthermore, a method for preparing the above-mentioned highly toughened, wear-resistant, and low-noise polyoxymethylene composite includes the following steps: Step S1: Mixing raw materials; Step S2, Extrusion granulation: Add the mixed material from step S1 into a twin-screw extruder for granulation; Step S3, Drying, to obtain a highly toughened, wear-resistant, and low-noise polyoxymethylene composite.

[0015] Furthermore, in step S2, the controlled temperatures of each zone of the twin-screw extruder are 165℃, 170℃, 175℃, 180℃, 185℃, 185℃, 190℃, 190℃, 190℃, and 190℃, respectively; the die head temperature is 185℃; the main feed rate is 200-500 kg / h; the screw speed is 200-500 r / min; and the vacuum degree is -0.1 to -0.5 MPa.

[0016] Furthermore, in step S3, the drying temperature is 80-120℃ and the drying time is 2-4 hours.

[0017] Compared with the prior art, the positive and beneficial effects of this invention are as follows: (1) This invention improves the toughness of polyoxymethylene composite materials by adding organosilicon mixed resin to polyoxymethylene resin to form an "island structure" in the polyoxymethylene matrix, which disperses and absorbs energy when the polyoxymethylene composite material is subjected to force; the organosilicon mixed resin has an organosilicon main chain that can act as a lubricating component, and an acrylic acid (AC) or vinyl acetate (VA) side chain that can act as a compatibility component. The organosilicon mixed resin has a core-shell structure. When mixed and compounded with polyoxymethylene, the organosilicon segments (low surface energy) will spontaneously migrate to and accumulate on the surface of the formaldehyde composite material to form a dense organosilicon lubricating surface layer, which can significantly reduce the friction coefficient and noise of the formaldehyde composite material, reduce wear caused by "adhesion-tear" during friction, and thus improve the wear resistance of the formaldehyde composite material; in addition, the organosilicon segments also have good flexibility and elasticity. When subjected to external friction, these chain segments can disperse local frictional forces through elastic deformation, avoiding stress concentration that could lead to surface scratches or peeling, thus reducing the wear of polyoxymethylene (POM) composite materials and improving their wear resistance. The main chain of the organosilicon mixed resin contains an organosilicon-Si-O- structure similar to the -CO- structure of POM, and has similar properties, enabling the organosilicon mixed resin to be well compatible with POM, resulting in a tighter bond between the two. The polar groups (such as carboxyl and ester groups) in the side chain acrylic acid (AC) or vinyl acetate (VA) molecules can form hydrogen bonds or dipole-dipole interactions with the carbonyl groups in POM or the amino / isocyanate groups in polyurethane, thereby enriching at the interface between the two phases and forming a "polar bridge" between POM and polyurethane. This reduces the interfacial tension between the two phases, promotes dispersion, and improves the compatibility between the formaldehyde composition system, thereby improving the toughness and wear resistance of the formaldehyde composition material.

[0018] (2) If the melt index of the copolymer is less than 5 g / min, the toughness and friction and wear performance of the polyoxymethylene composite material are significantly improved, but the molding and processing effect is poor; if the melt index is greater than 9 g / min, the toughness and friction and wear performance of the polyoxymethylene composite material are relatively low, but the molding and processing effect is good. Considering all factors, the present invention selects copolymers with a melt index range of 5-9 g / min, which can ensure that the toughness and friction and wear performance of the polyoxymethylene composite material are significantly improved, and the molding and processing effect is good.

[0019] (3) In this invention, polyoxymethylene, thermoplastic polyurethane and polyethylene glycol are mixed and then other additives are added. This allows a film to be formed on the surface of polyoxymethylene and thermoplastic polyurethane, which effectively adsorbs other powdered additives on the surface of polyoxymethylene and thermoplastic polyurethane, preventing the powdered additives from agglomerating and also playing an auxiliary lubricating role. This effectively improves the toughness and wear resistance of polyoxymethylene composite materials and reduces the noise of polyoxymethylene composite materials.

[0020] (4) The twin-screw extruder used in this invention has a rotation speed of 200-500 r / min, which can make the mixture fully and evenly mixed. If the rotation speed is too fast, the shear force is strong, and polyoxymethylene is easily decomposed, resulting in the general performance of the polyoxymethylene composite material. If the rotation speed is too slow, the shear effect is poor, the mixing is uneven, and it is impossible to obtain good performance of the polyoxymethylene composite material. In addition, the dual vacuum system in the twin-screw extruder is located in sections 7 and 9, which can effectively remove unstable small molecules such as moisture and formaldehyde from the system, thereby improving the toughness and wear resistance of the polyoxymethylene composite material.

[0021] (5) In this invention, the thermoplastic polyurethane and the organosilicon mixed resin have a synergistic effect, which makes the polyoxymethylene composite material have excellent toughness and wear resistance. At the same time, the formaldehyde adsorbent, antioxidant and extruder vacuum system work together to effectively absorb and remove free radicals and unstable small molecules generated in the system, reduce internal defects of polyoxymethylene mixture, thereby improving the toughness and wear resistance of polyoxymethylene composite material and reducing the noise of polyoxymethylene composite material. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] Unless otherwise specified, the experimental methods described in the examples and comparative examples are all conventional methods; the reagents, instruments and materials whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0024] In the examples and comparative examples, the average molecular weight of the thermoplastic polyurethane was 20,000-80,000. The molecular weight of thermoplastic polyurethane is closely related to the toughening effect. A high molecular weight results in poor processing performance, uneven distribution, and a generally poor toughening effect. If the molecular weight is too low, the thermoplastic polyurethane itself has poor impact resistance and cannot achieve a good toughening effect. The lubricant is polyethylene glycol, with an average molecular weight of 200-600. The mold release agent is pentaerythritol stearate. The formaldehyde adsorbent is melamine, used to absorb the formaldehyde produced by the thermal decomposition of polyoxymethylene, preventing the formaldehyde from being further oxidized to formic acid, which would cause the polyoxymethylene to undergo chain degradation and reduce the toughness of the polyoxymethylene composite material. The antioxidant is any one or two of hindered amine antioxidants or phosphite antioxidants, specifically antioxidant 1010 and antioxidant 168, with a mass ratio of 3:2. The particle size of the organosilicon mixed resin is 30µm, its main chain is an organosilicon structure, its content is 70%, and its side chains are acrylic acid (AC) or vinyl acetate (VA) structures.

[0025] Example 1 A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw materials in weight percentages: 88% copolyoxymethylene (melt index 5 g / 10 min, the melt index test conditions are 190℃ / 2.16KG), 10% thermoplastic polyurethane, 1% organosilicon mixed resin (side chain is acrylic acid AC), 0.1% polyethylene glycol, 0.1% mold release agent (pentaerythritol stearate), 0.5% formaldehyde absorbent (melamine), and 0.3% antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2).

[0026] This organosilicon mixed resin is obtained by the following preparation method: First, vinyltriethoxysilane monomer and octamethylcyclotetrasiloxane monomer, water, sodium dodecylbenzenesulfonate emulsifier, and potassium persulfate initiator are mixed and reacted at 70°C for 4 hours to generate an organosilicon seed emulsion. Then, water, sodium dodecylbenzenesulfonate emulsifier, acrylic monomer, and potassium persulfate initiator are added to the organosilicon seed emulsion. Sodium dodecylbenzenesulfonate emulsifier is added every 1 hour at 75°C, and the reaction is carried out for 8 hours. After the reaction is completed, the mixture is cooled to below 40°C, the pH is adjusted to 7-8 with ammonia, and a small amount of gel is removed by filtration to obtain an organosilicon mixed resin. The mass ratio of acrylic monomer, water, sodium dodecylbenzenesulfonate emulsifier, potassium persulfate initiator, and vinyltriethoxysilane monomer is 4:60:15:1.5:5; the mass ratio of vinyltriethoxysilane monomer to octamethylcyclotetrasiloxane monomer is 1:2.

[0027] A method for preparing a highly toughened, wear-resistant, and low-noise polyoxymethylene composite includes the following steps: Step S1: Weigh each raw material according to the above weight proportions. First, mix the organosilicon mixed resin, formaldehyde adsorbent melamine, mold release agent pentaerythritol stearate, and antioxidant evenly to obtain mixture A, which is then set aside. Step S2: Mix polyoxymethylene and thermoplastic polyurethane, then add polyethylene glycol, mix evenly to obtain mixture B, and set aside. Step S3: Add the mixture A obtained in step S1 to the mixture B obtained in step S2, mix evenly, and obtain premix C for later use. Step S4: Add the premix C obtained in step S3 to a twin-screw extruder for mixing and granulation; wherein the controlled temperatures of each zone of the twin-screw extruder are 165℃, 170℃, 175℃, 180℃, 185℃, 185℃, 190℃, 190℃, 190℃, and 190℃, respectively; the die head temperature is 185℃; the main feed rate is 200kg / h; the screw speed is 250r / min; and the vacuum degree is -0.1MPa. Step S5: After extrusion granulation, the obtained granules are dried in a drying oven at 80°C for 4 hours to obtain a highly toughened, wear-resistant, and low-noise polyoxymethylene composite.

[0028] Example 2 A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw materials in the following mass percentages: 80.8% copolyoxymethylene (melt index 9 g / 10 min, the melt index test conditions are 190℃ / 2.16KG), 15% thermoplastic polyurethane, 3% organosilicon mixed resin (side chain is acrylic acid AC), 0.3% polyethylene glycol, 0.1% mold release agent (pentaerythritol stearate), 0.5% formaldehyde absorbent (melamine), and 0.3% antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2).

[0029] This organosilicon mixed resin is obtained by the following preparation method: First, vinyltriethoxysilane monomer and octamethylcyclotetrasiloxane monomer, water, sodium dodecylbenzenesulfonate emulsifier, and potassium persulfate initiator are mixed and reacted at 80°C for 3 hours to generate an organosilicon seed emulsion. Then, water, sodium dodecylbenzenesulfonate emulsifier, acrylic monomer, and potassium persulfate initiator are added to the organosilicon seed emulsion. Sodium dodecylbenzenesulfonate emulsifier is added every 1 hour at 85°C, and the reaction is carried out for 6 hours. After the reaction is completed, the mixture is cooled to below 40°C, the pH is adjusted to 7-8 with ammonia, and a small amount of gel is removed by filtration to obtain an organosilicon mixed resin. The mass ratio of acrylic monomer, water, sodium dodecylbenzenesulfonate emulsifier, potassium persulfate initiator, and vinyltriethoxysilane monomer is 6:100:25:4:10; the mass ratio of vinyltriethoxysilane monomer to octamethylcyclotetrasiloxane monomer is 1:2.

[0030] A method for preparing a highly toughened, wear-resistant, and low-noise polyoxymethylene composite includes the following steps: Step S1: Weigh each raw material according to the above weight proportions. First, mix the organosilicon mixed resin, formaldehyde adsorbent melamine, mold release agent pentaerythritol stearate, and antioxidant evenly to obtain mixture A, which is then set aside. Step S2: Mix polyoxymethylene and thermoplastic polyurethane, then add polyethylene glycol, mix evenly to obtain mixture B, and set aside. Step S3: Add the mixture A obtained in step S1 to the mixture B obtained in step S2, mix evenly, and obtain premix C for later use. Step S4: Add the premix C obtained in step S3 to a twin-screw extruder for mixing and granulation; wherein the controlled temperatures of each zone of the twin-screw extruder are 165℃, 170℃, 175℃, 180℃, 185℃, 185℃, 190℃, 190℃, 190℃, and 190℃, respectively; the die head temperature is 185℃; the main feed rate is 200kg / h; the screw speed is 250r / min; and the vacuum degree is -0.1MPa. Step S5: After extrusion granulation, the obtained particles are dried in a drying oven at 120°C for 2 hours to obtain a highly toughened, wear-resistant, and low-noise polyoxymethylene composite.

[0031] Example 3 A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw materials in the following mass percentages: 76.3% copolyoxymethylene (melt index 7 g / 10 min, the melt index test conditions are 190℃ / 2.16KG), 20% thermoplastic polyurethane, 5% organosilicon mixed resin (side chain is acrylic acid AC), 0.5% polyethylene glycol, 0.1% mold release agent (pentaerythritol stearate), 0.5% formaldehyde absorbent (melamine), and 0.3% antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2).

[0032] This organosilicon mixed resin is obtained by the following preparation method: First, vinyltriethoxysilane monomer and octamethylcyclotetrasiloxane monomer, water, sodium dodecylbenzenesulfonate emulsifier, and potassium persulfate initiator are mixed and reacted at 75°C for 3.5 h to generate an organosilicon seed emulsion. Then, water, sodium dodecylbenzenesulfonate emulsifier, acrylic monomer, and potassium persulfate initiator are added to the organosilicon seed emulsion. Sodium dodecylbenzenesulfonate emulsifier is added every 1 h at 80°C, and the reaction is carried out for 7 h. After the reaction is completed, the mixture is cooled to below 40°C, the pH is adjusted to 7-8 with ammonia, and a small amount of gel is removed by filtration to obtain an organosilicon mixed resin. The mass ratio of acrylic monomer, water, sodium dodecylbenzenesulfonate emulsifier, potassium persulfate initiator, and vinyltriethoxysilane monomer is 5:80:20:3:8; the mass ratio of vinyltriethoxysilane monomer to octamethylcyclotetrasiloxane monomer is 1:2.

[0033] A method for preparing a highly toughened, wear-resistant, and low-noise polyoxymethylene composite includes the following steps: Step S1: Weigh each raw material according to the above weight proportions. First, mix the organosilicon mixed resin, formaldehyde adsorbent melamine, mold release agent pentaerythritol stearate, and antioxidant evenly to obtain mixture A, which is then set aside. Step S2: Mix polyoxymethylene and thermoplastic polyurethane, then add polyethylene glycol, mix evenly to obtain mixture B, and set aside. Step S3: Add the mixture A obtained in step S1 to the mixture B obtained in step S2, mix evenly, and obtain premix C for later use. Step S4: Add the premix C obtained in step S3 to a twin-screw extruder for mixing and granulation; wherein the controlled temperatures of each zone of the twin-screw extruder are 165℃, 170℃, 175℃, 180℃, 185℃, 185℃, 190℃, 190℃, 190℃, and 190℃, respectively; the die head temperature is 185℃; the main feed rate is 200kg / h; the screw speed is 250r / min; and the vacuum degree is -0.1MPa. Step S5: After extrusion granulation, the obtained particles are dried in a drying oven at 100°C for 4 hours to obtain a highly toughened, wear-resistant, and low-noise polyoxymethylene composite.

[0034] Comparative Example 1 A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw materials in the following mass percentages: 78.6% copolyoxymethylene (melt index 7 g / 10 min, the melt index test conditions are 190℃ / 2.16KG), 20% thermoplastic polyurethane, 0% silicone mixed resin, 0.5% polyethylene glycol, 0.1% mold release agent (pentaerythritol stearate), 0.5% formaldehyde absorbent (melamine), and 0.3% antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2).

[0035] The preparation method of a highly toughened, wear-resistant, and low-noise polyoxymethylene composite is the same as that in Example 3.

[0036] Comparative Example 2 A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw materials in the following mass percentages: 74.1% copolyoxymethylene (melt index 7 g / 10 min, the melt index test conditions are 190℃ / 2.16KG), 20% thermoplastic polyurethane, 5% organosilicon mixed resin (side chain is acrylic acid AC), 0% polyethylene glycol, 0.1% mold release agent (pentaerythritol stearate), 0.5% formaldehyde absorbent (melamine), and 0.3% antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2).

[0037] The preparation method of a highly toughened, wear-resistant, and low-noise polyoxymethylene composite is the same as that in Example 3.

[0038] Comparative Example 3 A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw materials in weight percentages: 72.6% copolyoxymethylene (melt index 7 g / 10 min, the melt index test conditions are 190℃ / 2.16KG), 20% thermoplastic polyurethane, 5% organosilicon mixed resin (side chain is acrylic acid AC), 1.5% polyethylene glycol, 0.1% mold release agent (pentaerythritol stearate), 0.5% formaldehyde absorbent (melamine), and 0.3% antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2).

[0039] The preparation method of a highly toughened, wear-resistant, and low-noise polyoxymethylene composite is the same as that in Example 3.

[0040] Comparative Example 4 A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw materials in weight percentages: 93.6% copolyoxymethylene (melt index 7 g / 10 min, the melt index test conditions are 190℃ / 2.16KG), 0% thermoplastic polyurethane, 5% organosilicon mixed resin (side chain is acrylic acid AC), 0.5% polyethylene glycol, 0.1% mold release agent (pentaerythritol stearate), 0.5% formaldehyde absorbent (melamine), and 0.3% antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2).

[0041] The preparation method of a highly toughened, wear-resistant, and low-noise polyoxymethylene composite is the same as that in Example 3.

[0042] Comparative Example 5 A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw materials in weight percentages: 73.6% copolyoxymethylene (melt index 7 g / 10 min, the melt index test conditions are 190℃ / 2.16KG), 20% thermoplastic polyurethane, 5% organosilicon mixed resin (vinyl acetate VA), 0.5% polyethylene glycol, 0.1% mold release agent (pentaerythritol stearate), 0.5% formaldehyde absorbent (melamine), and 0.3% antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2).

[0043] The preparation method of a highly toughened, wear-resistant, and low-noise polyoxymethylene composite is the same as that in Example 3.

[0044] Comparative Example 6 A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw materials in weight percentages: 76.3% copolyoxymethylene (melt index 4 g / 10 min, the melt index test conditions are 190℃ / 2.16KG), 20% thermoplastic polyurethane, 5% organosilicon mixed resin (side chain is acrylic acid AC), 0.5% polyethylene glycol, 0.1% mold release agent (pentaerythritol stearate), 0.5% formaldehyde absorbent (melamine), and 0.3% antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2).

[0045] The preparation method of a highly toughened, wear-resistant, and low-noise polyoxymethylene composite is the same as that in Example 3.

[0046] Comparative Example 7 A high-toughness, wear-resistant, and low-noise polyoxymethylene composite comprises the following raw materials in the following mass percentages: 76.3% copolyoxymethylene (melt index 10 g / 10 min, the melt index test conditions are 190℃ / 2.16 KG), 20% thermoplastic polyurethane, 5% organosilicon mixed resin (side chain is acrylic acid AC), 0.5% polyethylene glycol, 0.1% mold release agent (pentaerythritol stearate), 0.5% formaldehyde absorbent (melamine), and 0.3% antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:2).

[0047] The preparation method of a highly toughened, wear-resistant, and low-noise polyoxymethylene composite is the same as that in Example 3.

[0048] Comparative Example 8 A highly toughened, wear-resistant, and low-noise polyoxymethylene composite and its preparation method are exactly the same as those in Example 3, except that the organosilicon mixed resin is an organosilicon mixed resin without a core-shell structure.

[0049] Comparative Example 9 A highly toughened, wear-resistant, and low-noise polyoxymethylene composite and its preparation method are exactly the same as those in Example 3, except that the organosilicon mixed resin is replaced with an equal amount of methyl MQ silicone resin.

[0050] The high-toughness, wear-resistant, and low-noise polyoxymethylene composites prepared in Examples 1-3 and Comparative Examples 1-9 were injection molded into ISO standard samples, and their mechanical properties were tested under the following specific test conditions: Tensile properties were tested according to standard ISO 527:2012; notched impact strength of simply supported beams was tested according to standard ISO 180:2000; melt flow rate was tested according to standard ISO 1133, which reflects the processing performance of the material; friction, wear, and noise tests were conducted between similar materials using a pin-disc friction and wear testing machine. The pins were made of polyoxymethylene injection molding with a contact area of ​​4 × 10 mm; the plastic squares were 60 × 60 × 2 mm in size, injection molded, and fixed on the friction and wear testing machine after modification for testing. The test conditions were: load 50 N, rotation speed 200 r / min, radius 20 mm, time 2 h, and linear velocity 0.42 m / s; noise tests were conducted according to GB 3096-2008. The mechanical property test results are shown in Table 1, and the friction, wear, and noise performance are shown in Table 2.

[0051] Table 1. Mechanical property test results of the high-toughness, wear-resistant, and low-noise polyoxymethylene composites prepared in Examples 1-3 and Comparative Examples 1-9

[0052] Table 2. Tribological and wear-resistant, low-noise polyoxymethylene composites prepared in Examples 1-3 and Comparative Examples 1-9: test results of tribological and wear-resistant properties and noise levels.

[0053] As can be seen from the data in Tables 1 and 2, the high-toughness, wear-resistant, and low-noise polyoxymethylene composites prepared in Examples 1-3 of this invention possess high toughness and excellent wear resistance.Comparing Comparative Example 1 with Example 3, it can be seen that the toughness and wear resistance of the polyoxymethylene (POM) composite in Comparative Example 1 are significantly lower than those in Example 3, while the noise level is significantly higher. This is mainly because no silicone was added in Comparative Example 1, which prevents the formation of a "polar bridge" between POM and thermoplastic polyurethane, resulting in a significant decrease in the toughness and wear resistance of the POM composite and a significant increase in noise. Comparing Comparative Example 2 with Example 3, it can be seen that since polyethylene glycol was not added in Comparative Example 2, the toughness of the POM composite changed less, while the wear resistance decreased slightly and the noise increased slightly. Comparing Comparative Example 3 with Example 3, it can be seen that when the polyethylene glycol content increased from 0.5% in Example 3 to 1.5% in Comparative Example 3, the POM composite... The toughness of the material decreased, but the wear resistance and noise decreased slightly. The comparison between Comparative Examples 2 and 3 and Example 3 shows that, as an auxiliary lubricant, both insufficient and excessive amounts of polyethylene glycol affect the toughness, wear resistance, and noise of the polyoxymethylene (POM) composite. Therefore, this application selects an appropriate amount of polyethylene glycol. Comparing Comparative Example 4 with Example 3, it can be seen that, due to the absence of thermoplastic polyurethane in Comparative Example 4, the toughness of the POM composite is significantly reduced, and the noise increases. This is mainly because the lack of thermoplastic polyurethane prevents the formation of an "island structure" in the POM matrix, resulting in the inability to disperse and absorb energy when the POM composite material is subjected to stress, leading to reduced toughness and increased noise. Comparative Example 5 compared to Example 3... The comparison shows that when the side chain of the thermoplastic polyurethane is changed from acrylic acid (AC) to vinyl acetate (VA), the toughness, wear resistance, and noise reduction properties of the polyoxymethylene (POM) composite remain almost unchanged. This indicates that whether acrylic acid (AC) or vinyl acetate (VA) is used as a side chain in thermoplastic polyurethane, its impact on the overall performance of the POM composite is essentially the same. Comparing Comparative Example 6 with Example 3, it can be seen that the melt index of the copolymerized POM is less than 5 g / min, resulting in a significant improvement in the toughness and friction / wear properties of the POM composite material, but a poor molding and processing effect. Comparing Comparative Example 7 with Example 3, it can be seen that the melt index of the copolymerized POM is greater than 9 g / min, resulting in a lower improvement in the toughness and friction / wear properties of the POM composite material, but a better molding and processing effect. Overall, this comparison is acceptable. The invention selects copolymerized polyoxymethylene with a melt index range of 5-9 g / min, which can ensure significant improvement in the toughness and friction and wear performance of the polyoxymethylene composite material, and also achieve good molding and processing results. A comparison between Comparative Example 8 and Example 3 shows that the lack of a core-shell structure in the organosilicon mixed resin of Comparative Example 8 leads to reduced toughness and wear resistance of the polyoxymethylene and increased noise. A comparison between Comparative Example 9 and Example 3 shows that the absence of carboxyl or ester group structures in the side chains of the organosilicon mixed resin of Comparative Example 9 prevents the formation of hydrogen bonds or dipole-dipole interactions with the carbonyl groups in polyoxymethylene or the amino / isocyanate groups in polyurethane, reducing the compatibility between the polyoxymethylene composite system and thus decreasing the toughness and wear resistance of the formaldehyde composition material.

[0054] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly toughened, wear-resistant, and low-noise polyoxymethylene composite, characterized in that, It includes the following raw material components: copolyoxymethylene, thermoplastic polyurethane, and organosilicon mixed resin, wherein the mass ratio of the copolyoxymethylene, thermoplastic polyurethane, and organosilicon mixed resin is (74-88):(10-20):(1-5).

2. The high-toughness, wear-resistant, and low-noise polyoxymethylene composite according to claim 1, characterized in that, The main chain of the organosilicon mixed resin is an organosilicon structure, and the side chains are acrylic acid or vinyl acetate structures.

3. The high-toughness, wear-resistant, and low-noise polyoxymethylene composite according to claim 1, characterized in that, The melt index of the copolymerized formaldehyde ranges from 5 to 9 g / 10 min, and its melt index test conditions are 190℃ / 2.16 kg.

4. The high-toughness, wear-resistant, and low-noise polyoxymethylene composite according to claim 1, characterized in that, The polyoxymethylene compound also includes a lubricant.

5. The high-toughness, wear-resistant, and low-noise polyoxymethylene composite according to claim 1, characterized in that, The polyoxymethylene compound also includes a release agent.

6. The high-toughness, wear-resistant, and low-noise polyoxymethylene composite according to claim 1, characterized in that, The polyoxymethylene compound also includes a formaldehyde adsorbent.

7. The highly toughened, wear-resistant, and low-noise polyoxymethylene composite according to claim 1, characterized in that, The polyoxymethylene compound also includes antioxidants.

8. A method for preparing the high-toughness, wear-resistant, and low-noise polyoxymethylene composite as described in any one of claims 1-7, characterized in that, Includes the following steps: Step S1: Mixing raw materials; Step S2, Extrusion granulation: Add the mixed material from step S1 into a twin-screw extruder for granulation; Step S3, Drying, to obtain a highly toughened, wear-resistant, and low-noise polyoxymethylene composite.

9. The preparation method of a high-toughness, wear-resistant, and low-noise polyoxymethylene composite according to claim 8, characterized in that, In step S2, the controlled temperature of the twin-screw extruder is 165-190℃, the die head temperature is 185℃, the main feed rate is 200-500kg / h, the screw speed is 200-500r / min, and the vacuum degree is -0.1-0.5MPa.

10. The method for preparing a highly toughened, wear-resistant, and low-noise polyoxymethylene composite according to claim 8, characterized in that, In step S3, the drying temperature is 80-120℃ and the drying time is 2-4 hours.

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