POM composition as well as preparation method and application thereof

Abstract

The invention discloses a POM composition as well as a preparation method and application thereof. The POM composition comprises the following components in parts by weight: 100 parts of polyformaldehyde resin; and 2-15 parts of tungsten disulfide. Tungsten disulfide is introduced into a polyformaldehyde resin matrix to serve as a wear-resistant agent, tungsten disulfide is dispersed in the POM matrix to serve as a rigid supporting point, external loads are effectively borne and dispersed, deformation of the matrix under the stress effect is greatly inhibited, the overall bending modulus of the composite material is remarkably improved, and meanwhile, the composite material has the advantages of being good in wear resistance and good in wear resistance. The unique layered hexagonal crystal structure of tungsten disulfide enables interlayer binding force to be weak, the tungsten disulfide is prone to sliding in the friction process to form a lubricating transfer film, the friction coefficient and the abrasion loss are effectively reduced, in addition, the layered structure can absorb vibration energy through interlayer sliding, friction vibration transmission is restrained, and the friction coefficient and the abrasion loss are effectively reduced. The uniformly dispersed rigid particles can also reduce micro-vibration in the matrix, so that the operation noise is obviously reduced; therefore, the POM composition with high modulus, low abrasion, damping and noise reduction is realized.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a POM composition, its preparation method, and its application. Background Technology

[0002] Polyoxymethylene (POM) is a crystalline engineering plastic with excellent comprehensive properties, widely used in the automotive, electronics, and electrical industries. In certain specific applications, such as gears, bearings, and other precision mechanical parts, higher demands are placed on the material's overall performance. This requires not only low wear but also extremely high rigidity to resist deformation under load, ensuring transmission accuracy and durability. Furthermore, during high-speed operation of these precision mechanical parts, the noise generated by frictional vibration can severely affect the quietness of the equipment and the user experience. Therefore, the material must possess certain damping characteristics to effectively suppress vibration transmission and noise radiation.

[0003] To improve the wear resistance of polyoxymethylene (POM), modification with solid lubricants is commonly used in the field. Molybdenum disulfide (MoD) is a commonly used solid lubricant, whose layered structure effectively reduces the coefficient of friction. However, MoD often leaves acidic residues during production, or may exhibit acidity under certain conditions. Under the high temperature and high shear of melt processing, these acidic substances can violently catalyze the decomposition and chain breakage of POM molecular chains. This not only increases formaldehyde release during processing and deteriorates the production environment, but also damages the material's rigidity, causing a decrease in key indicators such as flexural modulus. When this type of material rubs against metal, the significant modulus difference leads to a sharp increase in wear, and it is prone to high-frequency vibration and noise during operation, making it difficult to meet the requirements for precision mechanical parts.

[0004] Therefore, how to effectively improve the wear resistance of POM while enhancing the material's rigidity and improving its damping and noise reduction characteristics remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention aims to provide a POM composition that combines high modulus, low wear, and damping noise reduction.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a POM composition comprising, by weight parts:

[0008] 100 parts of polyoxymethylene resin;

[0009] 2-15 parts of tungsten disulfide.

[0010] Preferably, the polyoxymethylene resin is a copolymerized polyoxymethylene.

[0011] Preferably, the melt flow rate of the polyoxymethylene resin at 190°C and 2.16 kg is 8-10 g / 10 min. The melt flow rate is tested according to Method A of ISO 1133:2005.

[0012] Preferably, the POM composition contains ≥70% polyoxymethylene resin by mass percentage.

[0013] The weight percentages of the tungsten disulfide can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 parts, as well as specific values ​​between the above-mentioned values.

[0014] Preferably, the tungsten disulfide content in the POM composition is 1.5%-9% by mass.

[0015] Preferably, the average particle size of the tungsten disulfide is 40 nm to 1000 nm; the average particle size of the tungsten disulfide can be 40 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 60 nm, 700 nm, 800 nm, 900 nm, or 1000 nm, or specific values ​​between the above values. More preferably, the average particle size of the tungsten disulfide is 50 nm to 600 nm.

[0016] Furthermore, the POM composition further includes 0.1-5 parts of molybdenum disulfide; the weight parts of molybdenum disulfide can be 0.1 parts, 0.5 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts or 5 parts, as well as specific values ​​between the above points.

[0017] Preferably, the mass ratio of molybdenum disulfide to tungsten disulfide is 1:(3-15); the mass ratio of molybdenum disulfide to tungsten disulfide can be 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, or 1:15. This invention has found that when the mass ratio of molybdenum disulfide to tungsten disulfide is within the specified range, the POM composition exhibits good damping and noise reduction effects. More preferably, the mass ratio of molybdenum disulfide to tungsten disulfide is 1:(6-12).

[0018] Preferably, the molybdenum disulfide has an average particle size of 1-5 μm, more preferably 1.5-3 μm.

[0019] The average particle size of the present invention was determined with reference to standard GB / T 19077-2016.

[0020] Furthermore, the POM composition, by weight, further includes 0.1-3 parts of additives; the additives include at least one of antioxidants and formaldehyde absorbents.

[0021] Preferably, the antioxidant includes, but is not limited to, at least one of hindered phenolic antioxidants, phosphate ester antioxidants, or thioester antioxidants. Preferably, the antioxidant is selected from phosphate ester antioxidants; the phosphate ester antioxidant is preferably a spirophosphite antioxidant.

[0022] Preferably, the formaldehyde absorbent includes, but is not limited to, allantoin.

[0023] Secondly, the present invention also provides a method for preparing the POM composition, comprising the following steps: mixing the components uniformly according to the formula to obtain a premix, and then melting, cooling, and granulating the premix using a twin-screw extruder to prepare the POM composition; wherein the temperatures of the screw barrels from the feed port to the die head of the twin-screw extruder are respectively: 130℃-170℃, 190℃-210℃, 190℃-220℃, 200℃-220℃, 190℃-220℃, 190℃-220℃, 190℃-220℃, 190℃-220℃, 190℃-220℃, 180℃-200℃, the screw speed is 250 rpm-350 rpm, the feed rate is 50 kg / h-200 kg / h, and the vacuum degree is -0.1~0 MPa.

[0024] Thirdly, the present invention also provides the application of the described POM composition in the manufacture of mechanical parts. Specifically, it is used in the manufacture of gears, bearings, etc. It is particularly suitable for the manufacture of precision mechanical parts.

[0025] Fourthly, the present invention provides a mechanical part comprising the POM composition described herein. The mechanical part may include, for example, a gear or a bearing.

[0026] The present invention has the following beneficial effects:

[0027] This invention introduces tungsten disulfide as a wear-resistant agent into a polyoxymethylene (POM) resin matrix, unexpectedly achieving a significant increase in the material's flexural modulus, an effective reduction in specific wear, and excellent noise reduction performance. When dispersed in the POM matrix, tungsten disulfide acts as a rigid support point, effectively bearing and dispersing external loads, greatly suppressing matrix deformation under stress, and significantly improving the overall flexural modulus of the composite material. Simultaneously, the unique layered hexagonal crystal structure of tungsten disulfide results in weak interlayer bonding, facilitating slippage during friction to form a lubrication transfer film, effectively reducing the coefficient of friction and wear. Furthermore, its layered structure absorbs vibrational energy through interlayer slippage, suppressing frictional vibration transmission, and the uniformly dispersed rigid particles also reduce micro-vibrations within the matrix, significantly lowering operating noise. Thus, a POM composition that balances high modulus, low wear, and damping noise reduction is achieved.

[0028] The present invention further employs tungsten disulfide and molybdenum disulfide in a specific ratio, which produces an excellent synergistic effect, enabling the composite material to maintain a high flexural modulus while further reducing the specific wear and achieving a good noise reduction effect, thus well meeting the high requirements of POM material for modulus, wear and noise reduction performance. Detailed Implementation

[0029] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0030] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0031] The materials used in the embodiments and comparative examples of this invention are described below, but are not limited to these materials.

[0032] Polyoxymethylene resin 1: Copolymerized polyoxymethylene, with a melt flow rate of 9 g / 10 min at 190℃ and 2.16 kg, Polyplastics M90-44;

[0033] Polyoxymethylene resin 2: Copolymerized polyoxymethylene, with a melt flow rate of 27 g / 10 min at 190℃ and 2.16 kg, Polyplastics M270-44;

[0034] Tungsten disulfide 1: Average particle size 50nm, YM-WS2-N50, Ningbo Yumu New Materials Co., Ltd.;

[0035] Tungsten disulfide 2: Average particle size 300nm; YM-WS2-N300, Ningbo Yumu New Materials Co., Ltd.

[0036] Tungsten disulfide 3: Average particle size 500nm; YM-WS2-N500, Ningbo Yumu New Materials Co., Ltd.

[0037] Tungsten disulfide 4: Average particle size 1000nm; YM-WS2-W01, Ningbo Yumu New Materials Co., Ltd.

[0038] Molybdenum disulfide 1: Average particle size 3μm; YM-WS2-W03, Ningbo Yumu New Materials Co., Ltd.

[0039] Molybdenum disulfide 2: Average particle size 5μm; YM-WS2-W05, Ningbo Yumu New Materials Co., Ltd.

[0040] Carbon fiber: FUY-110-D1212, Nantong Fuyuan New Material Technology Co., Ltd.;

[0041] Graphite: Flake graphite-299, Qingdao Pingdu Fukang Graphite;

[0042] Additive 1: Antioxidant 245 and Antioxidant 1098 are compounded in a mass ratio of 2:1. They are commercially available. The same additives were used in all parallel tests.

[0043] Additive 2: Spirophosphite antioxidant, Revonox 608, Qitai Technology;

[0044] Additive 3: Phosphite antioxidant, IRGAFOS® 168, BASF.

[0045] Preparation method of polypropylene composite material in the examples and comparative examples: According to the proportions in Table 1 or Table 2, the raw materials are mixed evenly in a high-speed mixer to obtain a premix. The premix is ​​melt-extruded, cooled, and granulated by a twin-screw extruder to prepare a POM composition. The temperatures of each screw barrel from the feed port to the die head of the twin-screw extruder are 160℃, 200℃, 210℃, 220℃, 220℃, 220℃, 210℃, 210℃, and 190℃, respectively. The screw speed is 350 rpm, the feed rate is 200 kg / h, and the vacuum degree is -0.1 MPa.

[0046] Relevant performance testing methods:

[0047] 1. Specific wear: The test was conducted according to Method B of JISK 7218-1986, with a rotation speed of 0.8 m / s, a load of 40 N, and a rotation distance of 3 km. During the friction process, a noise tester (model: Deli DL333201) was used to test the noise in decibels (tested according to standard GB3096-1993).

[0048] 2. Flexural modulus: Tested according to ISO 178-2019 at a speed of 2 mm / min.

[0049] Table 1: Distribution ratios (by weight) and performance test results for each group in Examples 1-7

[0050] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Polyoxymethylene resin 1 100 100 100 100 100 100 100 Tungsten disulfide 1 3 5 8 10 Tungsten disulfide 2 10 Tungsten disulfide 3 10 Tungsten disulfide 4 10 Additive 1 1.5 1.5 1.5 1.5 1.5 1.5 1.5 <![CDATA[Specific wear rate (10 -3 mm 3 / kg·km)]]> 972 631 384 358 641 723 1081 Flexural modulus (MPa) 2610 2814 3121 3271 3441 3481 3299 Friction noise (dB) 65 58 55 51 57 61 68

[0051] Table 2: Distribution ratios (by weight) and performance test results for each group in Examples 8-14

[0052] Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Polyoxymethylene resin 1 100 100 100 100 100 100 Polyoxymethylene resin 2 100 Tungsten disulfide 1 8 10 10 7 7.5 6 7 Molybdenum disulfide 1 1 0.5 2 Molybdenum disulfide 2 1 Additive 1 1.5 1.5 1.5 1.5 Additive 2 1.5 Additive 3 1.5 <![CDATA[Specific wear rate (10 -3 mm 3 / kg·km)]]> 320 337 352 304 341 378 357 Flexural modulus (MPa) 3181 3321 3287 3095 3103 2961 3157 Friction noise (dB) 53 49 51 51 53 50 54

[0053] Table 3: Distribution ratios (by weight) and performance test results for each group in Comparative Examples 1-3

[0054] Comparative Example 1 Comparative Example 2 Comparative Example 3 Polyoxymethylene resin 1 100 100 100 Tungsten disulfide 1 Molybdenum disulfide 1 8 1 1 carbon fiber 7 graphite 7 Additives 1.5 1.5 1.5 <![CDATA[Specific wear rate (10 -3 mm 3 / kg·km)]]> 1132 1174 1158 Flexural modulus (MPa) 2881 3116 2965 Friction noise (dB) 73 83 79

[0055] As can be seen from the above embodiments and comparative examples, by introducing tungsten disulfide as a wear-resistant agent into the polyoxymethylene resin matrix, the present invention unexpectedly achieves a significant increase in the flexural modulus of the material and an effective reduction in specific wear, while also taking into account the damping and noise reduction effect.

[0056] The present invention further employs tungsten disulfide and molybdenum disulfide in a specific ratio, which produces an excellent synergistic effect, enabling the composite material to maintain a high flexural modulus while further reducing the specific wear and achieving a good noise reduction effect, thus well meeting the high requirements of POM material for modulus, wear and noise reduction performance.

[0057] The above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A POM composition, characterized in that, By weight, it includes the following components: 100 parts of polyoxymethylene resin; 2-15 parts of tungsten disulfide.

2. The POM composition according to claim 1, characterized in that, The tungsten disulfide has an average particle size of 40nm-1000nm; preferably, the tungsten disulfide has an average particle size of 50nm-600nm.

3. The POM composition according to claim 1, characterized in that, Its components also include 0.1-5 parts of molybdenum disulfide; preferably, the mass ratio of molybdenum disulfide to tungsten disulfide is 1:(3-15).

4. The POM composition according to claim 3, characterized in that, The mass ratio of molybdenum disulfide to tungsten disulfide is 1:(6-12).

5. The POM composition according to claim 3, characterized in that, The molybdenum disulfide has an average particle size of 1-5 μm, preferably 1.5-3 μm.

6. The POM composition according to claim 1, characterized in that, The polyoxymethylene resin is a copolymerized polyoxymethylene.

7. The POM composition according to claim 1, characterized in that, The melt flow rate of the polyoxymethylene resin at 190℃ and 2.16kg is 8-10 g / 10min.

8. The POM composition according to claim 1, characterized in that, The product also includes 0.1-3 parts by weight of additives; said additives include at least one of antioxidants and formaldehyde absorbents.

9. A method for preparing a POM composition according to any one of claims 1-8, characterized in that, The process includes the following steps: mixing each component evenly according to the formula to obtain a premix; melting and extruding the premix using a twin-screw extruder, cooling, and granulating to prepare a POM composition.

10. A mechanical part, characterized in that, Includes the POM composition as described in any one of claims 1-8.