Preparation method of modified polyformaldehyde with conductive and wear-resistant functions
By chemically modifying carbon nanotubes and MoS2, modified polyoxymethylene (POM) was prepared, solving the problem of simultaneously improving conductivity and wear resistance in existing technologies. This resulted in high conductivity and high wear resistance in modified POM, while reducing energy consumption and equipment investment.
Patent Information
- Application Number
- CN202511634113.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-10
- Publication Date
- 2026-03-06
AI Technical Summary
Existing technologies cannot significantly improve the conductivity and wear resistance of polyoxymethylene at the same time. Traditional melt physical blending methods suffer from uneven dispersion of nanofillers and high energy consumption.
By chemically modifying carbon nanotubes and MoS2, and using silane coupling agents and boron trifluoride diethyl ether complex catalysts, modified polyoxymethylene (POM) was prepared. This process achieved uniform dispersion and strong bonding of the filler during polymerization, forming a three-dimensional network structure and improving conductivity and wear resistance.
It significantly improves the conductivity and wear resistance of modified polyoxymethylene, reduces energy consumption and improves the overall performance of the material, and avoids physical agglomeration and sedimentation.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of polyoxymethylene material technology, and in particular relates to a method for preparing modified polyoxymethylene with conductive and wear-resistant functions. Background Technology
[0002] Polyoxymethylene (POM) is a thermoplastic crystalline polymer with high elastic modulus, rigidity, and hardness, and can partially replace metals such as copper and steel in industries such as automobiles and machinery manufacturing. Modification of POM can significantly improve its performance and further broaden its application areas. For example, adding nanofillers and graphene can enhance the electrical conductivity of POM, while fillers such as polytetrafluoroethylene (PTFE) ultrafine powder and MoS2 can strengthen its wear resistance. Traditional POM modification methods generally employ melt physical blending, where trioxymethylene is polymerized under the catalysis of boron trifluoride diethyl ether complex to produce POM. The POM coarse material and nanofillers are then melt-blended at high temperature in an extruder, followed by underwater pelletizing, centrifugal separation, and drying. This method has drawbacks such as uneven dispersion of nanofillers and high equipment energy consumption. Furthermore, it is difficult to significantly improve both conductivity and wear resistance simultaneously through a simple blending method. The fundamental reason is that these two modification objectives place almost contradictory requirements on the properties of the filler, the interaction between the filler and the matrix, and the final microstructure of the material. Summary of the Invention
[0003] The technical problem to be solved by the present invention is to provide a method for preparing modified polyoxymethylene with conductive and wear-resistant functions that significantly improves conductivity and wear resistance.
[0004] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a method for preparing modified polyoxymethylene with conductive and wear-resistant functions, comprising the following steps: Step 1: Place 2-4 parts by weight of carbon nanotubes into 100 parts of an oxidant made by mixing concentrated HNO3 and concentrated H2SO4 in a volume ratio of 2-4:1. After the reaction is complete, wash and dry to obtain modified carbon nanomaterials. Step 2: Dissolve 2-5 parts by weight of coupling agent in 100 parts by weight of anhydrous ethanol, adjust the pH value to between 4 and 5, and obtain a silane coupling agent solution after the reaction is completed; soak 8-10 parts by weight of MoS2 powder in 1-3 parts by weight of silane coupling agent solution and react. After the reaction is completed, wash and dry the product to obtain modified MoS2. Step 3: Add 1-3 parts by weight of modified carbon nanomaterial and 1-3 parts by weight of modified MoS2 to 100 parts of paraformaldehyde, and then add 4-8 parts by weight of boron trifluoride diethyl ether complex catalyst. After the reaction is completed, the polymer is granulated underwater to obtain modified polyformaldehyde particles with conductive and wear-resistant functions.
[0005] Preferably, step 1 is as follows: 3 parts by weight of carbon nanotubes are placed in 100 parts by weight of an oxidant composed of concentrated HNO3 and concentrated H2SO4 mixed in a volume ratio of 3:1. The reaction temperature is 70-80℃, and the ultrasonic oxidation is carried out at a power of 400-500W for 5-10 hours. After the reaction is completed, the product is washed and dried to obtain modified carbon nanomaterials.
[0006] Preferably, step 2 is as follows: 3.5 parts by weight of silane coupling agent are dissolved in 100 parts by weight of anhydrous ethanol, the pH value is adjusted to between 4 and 5, and the reaction is carried out at 55 to 60°C for 1 to 3 hours to obtain a silane coupling agent solution; 9 parts by weight of MoS2 powder are soaked in 1.5 parts by weight of coupling agent solution, and ultrasonically stirred at 300 to 500W for 6 to 9 hours. After the reaction is completed, the product is washed and dried to obtain modified MoS2.
[0007] Preferably, step 3 is as follows: 2 parts by weight of modified carbon nanomaterial and 2 parts by weight of modified MoS2 are added to 100 parts of paraformaldehyde, and then 6 parts by weight of boron trifluoride diethyl ether complex catalyst are added. The polymerization reaction is carried out at 60-90°C for 4-6 hours. After the reaction is completed, the polymer is granulated underwater to obtain modified polyformaldehyde particles with conductive and wear-resistant functions.
[0008] Preferably, step 3 is as follows: 1 part of modified carbon nanomaterial and 3 parts of modified MoS2 are added to 100 parts of paraformaldehyde by weight, and then 6 parts of boron trifluoride diethyl ether complex catalyst are added. The polymerization reaction is carried out at 60-90°C for 4-6 hours. After the reaction is completed, the polymer is granulated underwater to obtain modified paraformaldehyde particles with conductive and wear-resistant functions.
[0009] Preferably, step 3 is as follows: 3 parts by weight of modified carbon nanomaterial and 1 part by weight of modified MoS2 are added to 100 parts of paraformaldehyde, and then 6 parts by weight of boron trifluoride diethyl ether complex catalyst are added. The polymerization reaction is carried out at 60-90°C for 4-6 hours. After the reaction is completed, the polymer is granulated underwater to obtain modified polyformaldehyde particles with conductive and wear-resistant functions.
[0010] Preferably, the silane coupling agent is one or more of γ-aminopropyltriethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-(methacryloyloxy)propyltrimethoxysilane.
[0011] Compared with the prior art, the advantages of the present invention are as follows: 1. Chemical modification of carbon nanotubes (CNTs) involves introducing -COOH groups onto the CNT surface through acid oxidation. After modification, the CNT surface contains carboxyl-COOH groups. The positively charged hydrogen (H) hydroxyl group can act as a hydrogen bond donor, forming hydrogen bonds with the lone pair of electrons (O) in the POM monomer, paraformaldehyde. The negatively charged carbonyl oxygen group can also form hydrogen bonds with the hydrogen atoms in the -OH or -OCH3 end groups of the POM monomer, thus creating an anchoring effect between them. Furthermore, the carboxyl-COOH group is a polar group, enhancing the interfacial bonding with the POM monomer. Through chemical modification, the interfacial compatibility between the inorganic filler and the organic matter is significantly improved, allowing the filler to effectively embed into the polymer chain, achieving stable and uniform dispersion and avoiding physical agglomeration and sedimentation within the POM monomer.
[0012] 2. MoS2 is chemically modified using a silane coupling agent. The silanol group (-Si-OH) at one end of the silane coupling agent reacts with the hydroxyl groups on the surface of MoS2 to form a strong covalent bond. The amino group (-NH2) at the other end is a polar functional group that forms hydrogen bonds with POM and its monomers. This modification improves the compatibility between inorganic materials and organic polymers, and also allows the filler to be efficiently embedded into the polymerization chain, avoiding physical agglomeration during polymerization and sedimentation in the POM monomer.
[0013] 3. Modified CNTs significantly improve the electrical conductivity of POM without affecting its mechanical properties. The addition of modified MoS2 enhances the wear resistance of POM. Furthermore, modified CNTs and modified MoS2 have a synergistic effect. The three-dimensional network structure formed by modified CNTs reduces the aggregation of MoS2, while the layered structure of modified MoS2 itself provides surface lubrication, reducing the shear stress experienced by CNTs during friction. Together, these factors result in a composite material that simultaneously possesses a low coefficient of friction, high wear resistance, and high electrical conductivity.
[0014] 4. By moving the composite nanomaterials from the post-processing stage to the polymerization stage, molecular-level dispersion is achieved through chemical modification, minimizing agglomeration and sedimentation, and ultimately forming a strong bond with the polymer molecular chains. Furthermore, simultaneous polymerization and modification eliminates the melt blending step, reducing the strength loss of polyoxymethylene due to shear blending and lowering energy consumption. Detailed Implementation
[0015] The present invention will be further described in detail below with reference to the embodiments.
[0016] Example 1: A method for preparing modified polyoxymethylene with conductive and wear-resistant properties, comprising the following steps: Step 1: Add 3 parts by weight of carbon nanotubes to 100 parts by weight of an oxidant consisting of a 3:1 volume mixture of concentrated HNO3 and concentrated H2SO4. The reaction temperature is 75℃, and ultrasonic oxidation is performed at 450W for 8 hours. After the reaction, the product is washed and dried to obtain modified carbon nanomaterials (abbreviated as modified CNTs). FTIR characterization shows that the CNTs exhibit a high viscosity at 1380-1420 cm⁻¹. -1 and 2500-3000 cm -1 CO stretching vibration peaks and OH stretching vibration peaks appeared respectively.
[0017] Step 2: Dissolve 3.5 parts by weight of silane coupling agent in 100 parts by weight of anhydrous ethanol, adjust the pH to between 4 and 5, and react at 58°C for 1.5 h to obtain a silane coupling agent solution. Soak 9 parts by weight of MoS2 powder in 1.5 parts by weight of the coupling agent solution, and ultrasonically stir at 400 W for 7.5 h. After the reaction is complete, wash and dry the product to obtain modified MoS2. Characterize by FTIR in the range of 3140–3520 cm⁻¹. -1 and 400~1100 cm -1 The peaks show -NH2 stretching vibration and Si-O-MoS2 stretching vibration, respectively. The silane coupling agent is one or more of γ-aminopropyltriethoxysilane (KH-550), vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane (KH-560), and γ-(methacryloyloxy)propyltrimethoxysilane (KH-570).
[0018] Step 3: Add 2 parts by weight of modified carbon nanomaterial and 2 parts by weight of modified MoS2 to 100 parts of trioxymethylene, and then add 6 parts by weight of boron trifluoride diethyl ether complex catalyst. The polymerization reaction is carried out at 75°C for 5 hours. After the reaction is completed, the polymer is granulated underwater to obtain modified polyoxymethylene particles (modified POM particles).
[0019] Example 2 is the same as Example 1 above, except that in step 3, 1 part of modified carbon nanomaterial, 3 parts of modified MoS2 are added to 100 parts of trioxymethylene and 6 parts of boron trifluoride diethyl ether complex catalyst, and the polymerization reaction is carried out at 75°C for 5 hours. After the reaction is completed, the polymer is granulated underwater to obtain modified POM particles.
[0020] Example 3 is the same as Example 1 above, except that in step 3, 3 parts of modified carbon nanomaterial, 1 part of modified MoS2 and 100 parts of trioxymethylene are added by weight, and 6 parts of boron trifluoride diethyl ether complex catalyst are added. The polymerization reaction is carried out at 75°C for 5 hours. After the reaction is completed, the polymer is granulated underwater to obtain modified POM particles.
[0021] Comparative Example 1: A method for preparing modified polyoxymethylene, comprising the following steps: Step 1: Place 3 parts by weight of carbon nanotubes into 100 parts by weight of oxidant, which is a mixture of concentrated HNO3 and concentrated H2SO4 in a volume ratio of 3:1. The reaction temperature is 75℃, and the ultrasonic oxidation time is 8h at 450W power. After the reaction is completed, the product is washed and dried to obtain modified carbon nanomaterials. Step 2: Add 4 parts by weight of modified carbon nanomaterial to 100 parts of trioxymethylene, add 6 parts by weight of boron trifluoride diethyl ether complex catalyst, stir evenly, and carry out polymerization reaction at 75°C for 5 hours. After the reaction is completed, the polymer is granulated underwater to obtain modified POM particles.
[0022] Comparative Example 2: A method for preparing modified polyoxymethylene, comprising the following steps: Step 1: Dissolve 3.5 parts by weight of silane coupling agent in 100 parts by weight of anhydrous ethanol, adjust the pH value to between 4 and 5, and react at 58°C for 1.5 h to obtain a silane coupling agent solution; immerse 9 parts by weight of MoS2 powder in 1.5 parts by weight of coupling agent solution, and ultrasonically stir at 400W for 7.5 h. After the reaction is completed, wash and dry the product to obtain modified MoS2.
[0023] Step 2: Add 4 parts by weight of modified MoS2 to 100 parts of paraformaldehyde, add 6 parts by weight of boron trifluoride diethyl ether complex catalyst, and carry out polymerization reaction at 75°C for 5 hours. After the reaction is completed, the polymer is granulated underwater to obtain modified POM particles.
[0024] Comparative Example 3: A method for preparing polyoxymethylene, comprising the following steps: taking 100 parts by weight of trioxymethylene, adding 6 parts by weight of boron trifluoride diethyl ether complex catalyst for polymerization reaction, and after the reaction is completed, underwater pelletizing to obtain POM base material.
[0025] Comparative Example 4: A method for preparing polyoxymethylene, comprising the following steps: adding 2 parts by weight of unmodified carbon nanomaterials and 2 parts by weight of unmodified MoS2 to 100 parts by weight of trioxymethylene, adding 6 parts by weight of boron trifluoride diethyl ether complex catalyst, and carrying out a polymerization reaction at 75°C for 5 hours. After the reaction is completed, the polymer is granulated underwater to obtain polyoxymethylene particles.
[0026] Comparative Example 5: A method for preparing modified polyoxymethylene, comprising the following steps: Step 1: Place 3 parts by weight of carbon nanotubes into 100 parts by weight of oxidant, which is a mixture of concentrated HNO3 and concentrated H2SO4 in a volume ratio of 3:1. The reaction temperature is 75℃, and the ultrasonic oxidation time is 8h at 450W power. After the reaction is completed, the product is washed and dried to obtain modified carbon nanomaterials. Step 2: Take 100 parts by weight of trioxymethylene, add 6 parts of boron trifluoride diethyl ether complex catalyst for polymerization reaction to prepare POM base material, and then melt-blend and granulate 4 parts of modified carbon nanomaterial with POM base material.
[0027] II. Analysis of Experimental Results Examples 1-3 tested the effects of different ratios of modified carbon nanotubes and modified MoS2 on the performance of POM and their synergistic effect. Comparative Example 1 tested the effect of modified nanotubes on POM performance, and Comparative Example 2 tested the effect of modified MoS2 on POM performance. Comparative Example 3 was a POM base without any added modifying materials, Comparative Example 4 tested the effect of unmodified carbon nanotubes and MoS2 on POM performance, and Comparative Example 5 was a modified POM particle prepared by first polymerizing and then melt-blending with modified nanofillers.
[0028] The volume resistivity, tensile strength, coefficient of friction, and wear rate of the POM prepared in Examples 1-3 and Comparative Examples 1-4 were tested respectively. The test results are summarized as follows: Table 1 Performance test results of POM
[0029] Table 2 below shows the results of CNT dispersion, volume resistivity, and tensile strength determination in modified POM for Comparative Examples 1 and 4. Table 2 Performance test results of POM modified with modified carbon nanomaterials added at different stages
[0030] A comparative analysis of the data in Tables 1 and 2 above shows that: 1. Comparison of Comparative Example 1 and Comparative Example 3 shows that modified CNT can significantly improve the conductivity of POM.
[0031] 2. Comparison of Comparative Example 2 and Comparative Example 3 shows that the addition of modified MoS2 can reduce the wear rate of POM and improve its wear resistance.
[0032] 3. Comparing Examples 1-3, it can be seen that the conductivity of modified POM gradually increases with the increase of modified CNT addition; simultaneously, the wear resistance of modified POM gradually increases with the increase of modified MoS2 addition. Furthermore, comparing Example 2 with Comparative Example 2, it can be seen that although the amount of modified MoS2 added is reduced, the wear resistance is actually improved, indicating that the addition of modified CNT has a certain synergistic effect on MoS2, improving tensile strength and conductivity while further enhancing wear resistance. Similarly, comparing Example 3 with Comparative Example 1, it can be seen that although the amount of modified CNT added is reduced, the conductivity of modified POM is slightly improved, indicating that the addition of modified MoS2 can improve wear resistance and tensile strength while synergistically reducing volume resistivity with CNT.
[0033] 4. Comparing Example 1 with Examples 2 and 3, it can be seen that the filler ratio in Example 1 can achieve a balanced index and the best overall performance. Further comparison between Example 1 and Comparative Example 4 shows that the unmodified filler has limited effect on improving the conductivity and wear resistance of POM due to the weakened interfacial bonding with POM monomers and its own agglomeration effect.
[0034] 5. Comparing Comparative Example 1 and Comparative Example 5, it can be seen that adding modified CNTs from the post-processing stage to the polymerization stage results in more uniform filler dispersion and significantly improved material performance. At the same time, it reduces the number of blending and re-granulation process steps, significantly reducing equipment investment and energy consumption.
[0035] The foregoing description is not intended to limit the invention, nor is the invention limited to the examples given. Any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the invention should also be considered within the protection scope of the invention.
Claims
1. A method for preparing a modified polyoxymethylene having an electrically conductive wear-resistant function, characterized by, The method comprises the following steps: Step 1: 2-4 parts of carbon nanotubes are put into 100 parts of an oxidant prepared by mixing concentrated HNO3 and concentrated H2SO4 in a volume ratio of 2-4:1, and the modified carbon nanomaterial is obtained after washing and drying after the reaction is completed; Step 2: 2-5 parts of a coupling agent are dissolved in 100 parts of anhydrous ethanol, and the pH value is adjusted to 4-5, and the silane coupling agent solution is obtained after the reaction is completed; 8-10 parts of MoS2 powder is soaked in 1-3 parts of the silane coupling agent solution for reaction, and the modified MoS2 is obtained after washing and drying the product after the reaction is completed; Step 3: 1-3 parts of the modified carbon nanomaterial and 1-3 parts of the modified MoS2 are added into 100 parts of trioxane, 4-8 parts of boron trifluoride ether complex catalyst is added, and the polymer is cut under water after the reaction is completed, so that the modified polyoxymethylene particles with conductive and wear-resistant functions are obtained.
2. The method for preparing modified polyoxymethylene with conductive wear-resistant function according to claim 1, characterized in that, In the step 1, 3 parts of carbon nanotubes are put into 100 parts of an oxidant prepared by mixing concentrated HNO3 and concentrated H2SO4 in a volume ratio of 3:1, the reaction temperature is 70-80℃, the ultrasonic oxidation time is 5-10 h under a power of 400-500 W, and the modified carbon nanomaterial is obtained after washing and drying the product after the reaction is completed.
3. The method for preparing modified polyoxymethylene with conductive wear-resistant function according to claim 1, characterized in that, In the step 2, 3.5 parts of a silane coupling agent are dissolved in 100 parts of anhydrous ethanol, the pH value is adjusted to 4-5, and the silane coupling agent solution is obtained after the reaction is completed at 55-60℃ for 1-3 h; 9 parts of MoS2 powder is soaked in 1.5 parts of the coupling agent solution, and the modified MoS2 is obtained after washing and drying the product after the reaction is completed under ultrasonic stirring at a power of 300-500 W for 6-9 h.
4. The method for preparing modified polyoxymethylene with conductive wear-resistant function according to claim 1, characterized in that, In the step 3, 2 parts of the modified carbon nanomaterial and 2 parts of the modified MoS2 are added into 100 parts of trioxane, 6 parts of boron trifluoride ether complex catalyst is added, and the polymer is cut under water after the reaction is completed at 60-90℃ for 4-6 h, so that the modified polyoxymethylene particles with conductive and wear-resistant functions are obtained.
5. The method of claim 1, wherein the modified polyoxymethylene having an electrically conductive wear-resistant function is prepared by adding a conductive filler to a polyoxymethylene resin, and then adding a modifier to the polyoxymethylene resin. In the step 3, 1 part of the modified carbon nanomaterial and 3 parts of the modified MoS2 are added into 100 parts of trioxane, 6 parts of boron trifluoride ether complex catalyst is added, and the polymer is cut under water after the reaction is completed at 60-90℃ for 4-6 h, so that the modified polyoxymethylene particles with conductive and wear-resistant functions are obtained.
6. The method of claim 1, wherein the modified polyoxymethylene having an electrically conductive wear resistance function is prepared by adding a conductive filler to a polyoxymethylene resin, and then adding a modifier to the polyoxymethylene resin. In the step 3, 3 parts of the modified carbon nanomaterial and 1 part of the modified MoS2 are added into 100 parts of trioxane, 6 parts of boron trifluoride ether complex catalyst is added, and the polymer is cut under water after the reaction is completed at 60-90℃ for 4-6 h, so that the modified polyoxymethylene particles with conductive and wear-resistant functions are obtained.
7. A method for preparing a modified polyoxymethylene with conductive and wear-resistant properties according to any one of claims 1-6, characterized in that, The silane coupling agent is one or more than one of γ-aminopropyl triethoxysilane, vinyl triethoxysilane, γ-glycidyl ether propyl trimethoxysilane and γ-(methacryloyloxy) propyl trimethoxysilane.