Magnetic flux guide polyketone material and method of making

Abstract

The present application relates to the technical field of magnetic polymer composites, and particularly relates to a magnetically conductive polyketone material and a preparation method thereof. The magnetically conductive polyketone material is prepared from the following components by weight: 100 parts of polyketone resin, 40-85 parts of modified magnetic powder, 2.5-10.5 parts of toughening agent, and 0.5-2 parts of lubricant. The modified magnetic powder comprises a magnetic powder core and a polyimide layer and a titanate coupling agent layer successively coated on the surface of the magnetic powder core from inside to outside. The crystallinity of the polyketone resin is 40-55%. The present application uses the modified magnetic powder in combination with the polyketone resin with suitable crystallinity to obtain the magnetically conductive polyketone material with good mechanical properties and processing fluidity. By adding the appropriate amount of toughening agent, the impact resistance of the material is effectively improved, and the micro-interface bonding performance between the polyketone resin and the modified magnetic powder is enhanced, and the magnetic properties of the magnetically conductive polyketone material are improved.

Description

Technical Field

[0001] This invention relates to the field of magnetic polymer composite materials technology, and in particular to a magnetically conductive polyketone material and its preparation method. Background Technology

[0002] Magnetic polymer composites have become an important research direction in the field of functional composite materials in recent years. By filling a polymer matrix with magnetic powder, these composites impart magnetic response properties to the material while retaining the advantages of polymers such as light weight, flexibility, and ease of processing. Commonly used polymer matrices include epoxy resins and polyamides. By selecting different types of polymer matrices, composite materials can achieve differentiated properties.

[0003] Polyketone resin is a novel polymer material copolymerized from carbon monoxide and olefins. It possesses excellent chemical resistance, mechanical strength, and dimensional stability, and has broad application prospects in electronics, automotive, and aerospace fields. However, polyketone resin exhibits poor interfacial compatibility with inorganic magnetic materials. Magnetic powder tends to agglomerate within polyketone resin, leading to decreased mechanical properties, poor processing flowability, and uneven magnetic property distribution in the composite material. Furthermore, polyketone resin has a narrow processing temperature window, and conventional magnetic powder modification processes can easily trigger polyketone resin degradation, thereby affecting the performance of the composite material.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a magnetically conductive polyketone material and its preparation method. The magnetically conductive polyketone material of this invention has good mechanical properties, processing fluidity and magnetic properties.

[0006] To achieve the above-mentioned objectives of the present invention, the first aspect of the present invention provides a magnetically conductive polyketone material, the raw materials of which include the following components by weight: 100 parts of polyketone resin, 40-85 parts of modified magnetic powder, 2.5-10.5 parts of toughening agent and 0.5-2 parts of lubricant; The modified magnetic powder includes a magnetic powder core and a polyimide layer and a titanate coupling agent layer that are sequentially coated on the surface of the magnetic powder core from the inside out. The crystallinity of the polyketone resin is 40%~55%.

[0007] In a specific embodiment of the present invention, the melt flow rate of the polyketone resin at 240°C and 2.16 kg is 55~65 g / 10 min.

[0008] In a specific embodiment of the present invention, the polyketone resin is obtained by copolymerization of carbon monoxide, ethylene and propylene; the propylene content is 2 wt% to 8 wt%.

[0009] In a specific embodiment of the present invention, the magnetic powder core includes at least one of iron tetroxide and rare earth neodymium iron boron magnetic powder.

[0010] In a specific embodiment of the present invention, the toughening agent includes at least one of maleic anhydride-grafted ethylene-octene copolymer, maleic anhydride-grafted styrene-ethylene-butene-styrene block copolymer, and methyl methacrylate-butadiene-styrene terpolymer.

[0011] In a specific embodiment of the present invention, the butadiene content in the methyl methacrylate-butadiene-styrene terpolymer is 40 wt% to 60 wt%.

[0012] In a specific embodiment of the present invention, the lubricant includes at least one of N,N'-ethylene bis-stearamide, pentaerythritol stearate, zinc stearate, and polyethylene wax.

[0013] The second aspect of the present invention provides a method for preparing the magnetically conductive polyketone material provided in the first aspect of the present invention, comprising the following steps: feeding a mixture of polyketone resin, lubricant, toughening agent and modified magnetic powder through the main feed port and side feed port of a twin-screw extruder respectively, and performing melt extrusion granulation; The temperature of the melt extrusion is 210~245℃.

[0014] In a specific embodiment of the present invention, the twin-screw extruder includes ten temperature zones, and the temperatures of each zone are set as follows: Zone 1 210~220℃, Zone 2 235~245℃, Zone 3 235~245℃, Zone 4 235~245℃, Zone 5 225~235℃, Zone 6 225~235℃, Zone 7 225~235℃, Zone 8 225~235℃, Zone 9 230~240℃, and Zone 10 235~245℃.

[0015] In a specific embodiment of the present invention, the preparation method of the modified magnetic powder includes the following steps: (a) Add polyamic acid to the dispersion containing unmodified magnetic powder, then adjust the pH to 7.5-8.5, keep the reaction at 120-150℃ for 3-5 h, collect the solid phase after solid-liquid separation and dry it; imidize the dried solid phase at 200-250℃ for 2-3 h to obtain magnetic powder coated with polyimide layer. (b) The magnetic powder coated with the polyimide layer is dispersed in anhydrous ethanol, a titanate coupling agent is added, and the mixture is stirred at 60-80°C for 1.5-3 h. After solid-liquid separation, the solid phase is collected and dried to obtain the modified magnetic powder.

[0016] In a specific embodiment of the present invention, in step (a), the mass of the polyamic acid is 5% to 10% of the mass of the unmodified magnetic powder.

[0017] In a specific embodiment of the present invention, in step (b), the mass of the titanate coupling agent is 2% to 5% of the mass of the unmodified magnetic powder.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs modified magnetic powder double-coated with polyimide and titanate coupling agent, combined with polyketone resin with suitable crystallinity, to achieve uniform dispersion of the modified magnetic powder in the polyketone resin, thereby obtaining a magnetically conductive polyketone material with both good mechanical properties and processing fluidity. Furthermore, by adding an appropriate amount of toughening agent, not only is the impact resistance of the material effectively improved and the generation of microcracks suppressed, but the micro-interfacial bonding performance between the polyketone resin and the modified magnetic powder is also enhanced, thereby further improving the magnetic properties of the magnetically conductive polyketone material. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0020] The first aspect of the present invention provides a magnetically conductive polyketone material, the raw materials of which include the following components by weight: 100 parts of polyketone resin, 40-85 parts of modified magnetic powder, 2.5-10.5 parts of toughening agent and 0.5-2 parts of lubricant; The modified magnetic powder includes a magnetic powder core and a polyimide layer and a titanate coupling agent layer that are sequentially coated on the surface of the magnetic powder core from the inside out. The crystallinity of the polyketone resin is 40%~55%.

[0021] This invention employs modified magnetic powder double-coated with polyimide and titanate coupling agent, combined with polyketone resin with suitable crystallinity, to achieve uniform dispersion of the modified magnetic powder in the polyketone resin, thereby obtaining a magnetically conductive polyketone material with both good mechanical properties and processing fluidity. Furthermore, by adding an appropriate amount of toughening agent, not only is the impact resistance of the material effectively improved and the generation of microcracks suppressed, but the micro-interfacial bonding performance between the polyketone resin and the modified magnetic powder is also enhanced, thereby further improving the magnetic properties of the magnetically conductive polyketone material.

[0022] Polyketone (POK) resin is a copolymer obtained by alternating copolymerization of carbon monoxide (CO) and olefins. The strong dipole interaction between carbonyl groups in the polyketone polymer chain gives it a high melting point, while its decomposition temperature is close to its melting point, resulting in a narrow processing temperature window. Improper processing conditions can easily cause degradation of polyketone resin, leading to a deterioration in the performance of magnetically conductive polyketone materials. By using ethylene and propylene as olefin monomers and adjusting the amount of propylene monomer, the crystallinity of the polyketone resin can be adjusted to 40%~55%, which is beneficial to the balance between the processing performance, mechanical properties, and magnetic properties of magnetically conductive polyketone materials.

[0023] In some embodiments, the crystallinity of the polyketone resin is 40% to 55%, specifically within the range of 40%, 42%, 45%, 48%, 50%, 52%, 55%, or any combination thereof. If the crystallinity of the polyketone resin is too high, the molecular chain mobility decreases, and the flowability deteriorates, making processing difficult and hindering the dispersion of the modified magnetic powder. This can easily introduce microscopic defects, leading to a decrease in magnetism. Conversely, if the crystallinity of the polyketone resin is too low, although it facilitates the dispersion of the modified magnetic powder, it will significantly reduce the mechanical properties of the obtained magnetically conductive polyketone material.

[0024] In some embodiments, the melt flow rate of the polyketone resin at 240°C and 2.16 kg is 55~65 g / 10 min, specifically within the range of 55 g / 10 min, 58 g / 10 min, 60 g / 10 min, 62 g / 10 min, 65 g / 10 min, or any combination thereof. Using a polyketone resin with a melt flow rate that meets the above conditions is more conducive to ensuring a balance between processing fluidity, mechanical properties, and magnetism in the magnetically conductive polyketone material. If the melt flow rate is too high, it is detrimental to the mechanical properties of the magnetically conductive polyketone material; if the melt flow rate is too low, it is detrimental to the uniform dispersion of the modified magnetic powder and its processing fluidity.

[0025] In some embodiments, the polyketone resin is obtained by copolymerization of carbon monoxide, ethylene, and propylene; the propylene content is 2 wt% to 8 wt%, specifically within the range of 2 wt%, 4 wt%, 5 wt%, 6 wt%, 8 wt%, or any combination thereof. If the propylene content is too high, the crystallinity decreases, which is detrimental to the mechanical properties of the magnetically conductive polyketone material; if the propylene content is too low, the crystallinity is too high, which is detrimental to the processing flowability and magnetism of the magnetically conductive polyketone material.

[0026] In some embodiments, the modified magnetic powder comprises a magnetic powder core and a polyimide layer and a titanate coupling agent layer sequentially coated on the surface of the magnetic powder core from the inside out; the magnetic powder core comprises at least one of iron(III) oxide and rare-earth neodymium iron boron magnetic powder. In this invention, a polyimide layer is first coated on the surface of the magnetic powder core. The polyimide layer has good adhesion, allowing it to tightly coat the magnetic powder surface and inhibiting powder agglomeration; furthermore, the polyimide has good high-temperature resistance, protecting the magnetic powder from thermal shear damage during high-temperature processing. A titanate coupling agent layer is further coated on the surface of the polyimide layer through a chemical bonding reaction. The organic groups of the titanate coupling agent can physically entangle with the polyketone resin molecular chains, significantly improving the interfacial compatibility between the magnetic powder and the polyketone resin, and promoting uniform dispersion of the magnetic powder in the polyketone resin matrix.

[0027] In some embodiments, the polyimide layer is formed by in-situ imidization of a polyimide precursor on the surface of a magnetic powder core; the polyimide precursor includes, but is not limited to, polyamic acid.

[0028] In some embodiments, the titanate coupling agent layer is formed by in-situ reaction of the titanate coupling agent on the surface of magnetic powder coated with a polyimide layer; the titanate coupling agent includes monoalkoxy pyrophosphate type titanate, specifically the titanate coupling agent GR-201 (isopropyltris(dioctylpyrophosphate)titanate).

[0029] In some embodiments, the magnetic powder core comprises at least one of magnetite (Fe3O4) and rare-earth neodymium iron boron (NdFeB) magnetic powder. Further, the particle size of the magnetic powder core is 38-150 μm, specifically within the range of 40 μm, 80 μm, 100 μm, 120 μm, 150 μm, or any combination thereof.

[0030] In some embodiments, based on 100 parts by weight of the polyketone resin, the amount of modified magnetic powder is 40-85 parts by weight, specifically 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or any combination thereof, such as 50-70 parts by weight. Controlling the amount of modified magnetic powder within the above range is beneficial for balancing the impact resistance, magnetic properties, and processing fluidity of the magnetically conductive polyketone material. If the amount of modified magnetic powder is too low, it is detrimental to the magnetic properties of the magnetically conductive polyketone material; if the amount of modified magnetic powder is too high, it not only negatively affects the impact resistance of the magnetically conductive polyketone material but also leads to poor processing fluidity.

[0031] In some embodiments, the toughening agent includes at least one selected from maleic anhydride-grafted ethylene-octene copolymer (POE-g-MAH), maleic anhydride-grafted styrene-ethylene-butene-styrene block copolymer (SEBS-g-MAH), and methyl methacrylate-butadiene-styrene terpolymer (MBS). Using the above-mentioned toughening agent can improve the impact resistance of magnetically conductive polyketone materials.

[0032] In some embodiments, the toughening agent is preferably MBS. The inventors of this invention have discovered that MBS has better compatibility with polyketone resin and exhibits a significant toughening effect. At the same dosage, MBS not only better enhances the impact resistance of magnetically conductive polyketone materials but also significantly improves the microscopic interfacial bonding between the polyketone material and the modified magnetic powder, thereby improving the magnetic properties of the magnetically conductive polyketone material.

[0033] In some embodiments, the butadiene content in the MBS is 40 wt% to 60 wt%, specifically 40 wt%, 45 wt%, 50 wt%, 55 wt%, 58 wt%, 60 wt%, or any combination thereof, such as 55 wt% to 60 wt%. MBS is a core-shell structured material prepared by emulsion graft polymerization of methyl methacrylate, butadiene, and styrene. A butadiene content within the above range ensures uniform dispersion of MBS in the magnetically conductive polyketone material and improves its impact resistance and magnetic properties. If the butadiene content is too high, MBS easily agglomerates in the polyketone material, forming larger particles, which not only worsens dispersibility and makes it difficult to further improve impact resistance, but also hinders the uniform dispersion of modified magnetic powder in the polyketone resin, affecting magnetic properties. If the butadiene content is too low, the improvement in the impact resistance of the magnetically conductive polyketone material is not significant.

[0034] In some embodiments, based on 100 parts by weight of the polyketone resin, the amount of the toughening agent is 2.5 to 10.5 parts by weight, specifically 2.5 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 10.5 parts by weight, or any combination thereof.

[0035] In some embodiments, the lubricant includes at least one of N,N'-ethylene bis-stearamide (EBS), pentaerythritol stearate (PETS), zinc stearate, and polyethylene wax. The introduction of the lubricant can reduce the melt viscosity of the material during extrusion, reduce equipment wear, and improve the surface smoothness of the material.

[0036] In some embodiments, based on 100 parts by weight of the polyketone resin, the amount of the lubricant is 0.5 to 2 parts by weight, specifically 0.5 parts by weight, 0.8 parts by weight, 1 part by weight, 1.2 parts by weight, 1.5 parts by weight, 1.8 parts by weight, 2 parts by weight, or any combination thereof.

[0037] In some embodiments, the raw materials for preparing the magnetically conductive polyketone material also include optional antioxidants. Further, the antioxidants include, but are not limited to, at least one of antioxidant 1010, antioxidant 168, and antioxidant 1076. The introduction of antioxidants can prevent thermo-oxidative degradation of the polyketone resin during melt extrusion, ensuring the stability of the material's properties.

[0038] In some embodiments, based on 100 parts by weight of the polyketone resin, the amount of the antioxidant is 0.2 to 0.6 parts by weight, specifically 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, or any combination thereof.

[0039] The second aspect of the present invention provides a method for preparing the magnetically conductive polyketone material provided in the first aspect of the present invention, comprising the following steps: feeding a mixture of polyketone resin, lubricant, toughening agent, optional antioxidant and modified magnetic powder through the main feed port and side feed port of a twin-screw extruder respectively, and performing melt extrusion granulation; wherein the temperature of the melt extrusion is 210~245℃.

[0040] In some embodiments, the preparation of the mixture includes: weighing polyketone resin, lubricant, toughening agent, and optional antioxidant in proportion, mixing them in a high-speed mixer at 80-100°C and 300-500 rpm for 5-10 minutes to obtain the mixture.

[0041] In some embodiments, the twin-screw extruder includes ten temperature zones, each with the following temperatures: Zone 1 210~220℃, Zone 2 235~245℃, Zone 3 235~245℃, Zone 4 235~245℃, Zone 5 225~235℃, Zone 6 225~235℃, Zone 7 225~235℃, Zone 8 225~235℃, Zone 9 230~240℃, and Zone 10 235~245℃. The temperature range of this invention is adapted to the processing characteristics of polyketone resin, ensuring both the uniform dispersion of the magnetically conductive polyketone material and effectively preventing its degradation, thus guaranteeing the mechanical properties of the magnetically conductive polyketone material.

[0042] In some embodiments, the main rotor speed of the twin-screw extruder can be 280~420 rpm, specifically a range of 280 rpm, 300 rpm, 350 rpm, 400 rpm, 420 rpm, or any combination thereof; the length-to-diameter ratio of the screw of the twin-screw extruder is (40~45):1. This ensures thorough mixing and plasticization of the material.

[0043] In some embodiments, the main feed port is connected to one zone of the twin-screw extruder, and the side feed port is connected to the fourth zone of the twin-screw extruder. This ensures both the uniform dispersion of the modified magnetic powder in the polyketone material and prevents the oxidation of the magnetic powder.

[0044] In some embodiments, after melt extrusion granulation, the material is dried at 80-100°C and then magnetized. Further, in the magnetization process, the magnetic field strength is 800-1200 kA / m, specifically within the range of 800 kA / m, 900 kA / m, 1000 kA / m, 1100 kA / m, 1200 kA / m, or any combination thereof.

[0045] In some embodiments, the method for preparing the modified magnetic powder includes the following steps: (a) Add polyamic acid to the dispersion containing unmodified magnetic powder, then adjust the pH to 7.5-8.5, keep the reaction at 120-150℃ for 3-5 h, collect the solid phase after solid-liquid separation and dry it; imidize the dried solid phase at 200-250℃ for 2-3 h to obtain magnetic powder coated with polyimide layer. (b) The magnetic powder coated with the polyimide layer is dispersed in anhydrous ethanol, a titanate coupling agent is added, and the mixture is stirred at 60-80°C for 1.5-3 h. After solid-liquid separation, the solid phase is collected and dried to obtain the modified magnetic powder.

[0046] In some embodiments, the dispersion containing unmodified magnetic powder includes unmodified magnetic powder and an organic solvent. Further, the organic solvent includes N-methylpyrrolidone.

[0047] In some embodiments, the mass ratio of the unmodified magnetic powder to the organic solvent in the dispersion containing the unmodified magnetic powder is 1:(3~5).

[0048] In some embodiments, the preparation of the dispersion containing unmodified magnetic powder includes: weighing unmodified magnetic powder and a first organic solvent in proportion, mixing them, and then ultrasonically dispersing them for 30-60 min to obtain the dispersion containing unmodified magnetic powder.

[0049] In some embodiments, before preparing the dispersion, the unmodified magnetic powder is further subjected to ball milling and sieving to obtain unmodified magnetic powder with a particle size of 38~150 μm. Ball milling is a conventional ball milling operation, and it is sufficient to obtain magnetic powder with a particle size that meets the corresponding range, so it will not be described in detail here.

[0050] In some embodiments, in step (a), the mass of the polyamic acid is 5% to 10% of the mass of the unmodified magnetic powder, specifically within the range of 5%, 6%, 7%, 8%, 9%, 10%, or any combination thereof. Controlling the amount of polyamic acid within the above range helps to form a uniformly coated polyimide layer on the surface of the magnetic powder. If the amount of polyamic acid is too low, the uniformity of the polyimide layer coating is poor, and the suppression of magnetic powder agglomeration is not significant, resulting in a decrease in the strength and magnetic properties of the magnetically conductive polyketone material.

[0051] In some implementations, in step (a), triethanolamine is used to adjust the pH to 7.5-8.5.

[0052] In some embodiments, in step (a), after adjusting the pH to 7.5-8.5, the reaction is kept at 120-150°C for 3-5 hours. The specific reaction temperature can be 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C or any combination thereof, and the reaction time can be 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours or any combination thereof.

[0053] In some embodiments, in step (a), after reacting at 120~150℃ for 3~5 h, solid-liquid separation is carried out by means of vacuum filtration, the solid phase is collected, and then dried at 75~85℃.

[0054] In some embodiments, in step (a), the imidization temperature is 200~250°C, specifically 200°C, 210°C, 220°C, 230°C, 240°C, 250°C or any combination thereof; the imidization time is 2~3 h, specifically 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h or any combination thereof.

[0055] In some embodiments, in step (a), the imidization treatment is carried out under a protective atmosphere. This protective atmosphere includes, but is not limited to, at least one of nitrogen or argon. Other steps that may involve oxidation may also be carried out under a protective atmosphere as needed.

[0056] In some embodiments, in step (b), the mass ratio of the magnetic powder coated with the polyimide layer to the anhydrous ethanol is 1:(4~6).

[0057] In some embodiments, in step (b), the mass of the titanate coupling agent is 2% to 5% of the mass of the unmodified magnetic powder, specifically a range of 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination thereof. Controlling the amount of titanate coupling agent within the above range helps to form a uniform titanate coupling agent layer on the surface of the polyimide layer.

[0058] In some embodiments, in step (b), the reaction is stirred at 60-80°C for 1.5-3 h, and the specific reaction temperature can be 60°C, 65°C, 70°C, 75°C, 80°C or any combination thereof; the specific reaction time can be 1.5 h, 1.8 h, 2 h, 2.5 h, 3 h or any combination thereof.

[0059] In some embodiments, in step (b), after the stirring reaction is completed, solid-liquid separation is performed by means of vacuum filtration, the solid phase is collected, and the solid phase is washed 2 to 3 times with anhydrous ethanol, and then vacuum dried at 55 to 65°C.

[0060] In some embodiments, the magnetically conductive polyketone material prepared by the preparation method of the present invention has a tensile strength ≥75 MPa, specifically a range of 75 MPa, 78 MPa, 80 MPa, 82 MPa, 85 MPa, 88 MPa, 90 MPa, 92.3 MPa or any combination thereof.

[0061] In some embodiments, the magnetically conductive polyketone material prepared by the method of the present invention has an impact strength ≥11 kJ / m. 2 Specifically, it can be 11 kJ / m 2 12 kJ / m 2 13 kJ / m 2 14 kJ / m 2 15 kJ / m 2 16 kJ / m 2 16.5kJ / m 2 Or a range consisting of any two of them.

[0062] In some embodiments, the magnetically conductive polyketone material prepared by the preparation method of the present invention has a melt index ≥ 7.0 g / 10 min, specifically it can be a range of 7.0 g / 10 min, 7.5 g / 10 min, 8 g / 10 min, 8.5 g / 10 min, 9 g / 10 min, 9.2 g / 10 min or any combination thereof.

[0063] In some embodiments, the magnetically conductive polyketone material prepared by the preparation method of the present invention has a remanence ≥0.40 T, specifically a range of 0.40 T, 0.42 T, 0.50 T, 0.80 T, 1.00 T, 1.12 T or any two of these ranges.

[0064] In some embodiments, the magnetically conductive polyketone material prepared by the preparation method of the present invention has an intrinsic coercivity ≥60 kA / m, specifically within the range of 60 kA / m, 63 kA / m, 70 kA / m, 75 kA / m, 80 kA / m, 90 kA / m, 98 kA / m, 102 kA / m, or any combination thereof.

[0065] In some embodiments, the magnetically conductive polyketone material prepared using the method of the present invention has a maximum magnetic energy product ≥ 1.4 kJ / m. 3 Specifically, it can be 1.4 kJ / m 3 1.8 kJ / m 3 2.0 kJ / m 3 2.2 kJ / m 3 2.5 kJ / m 3 2.8 kJ / m 3 3 kJ / m 3 3.2 kJ / m 3 3.5 kJ / m 3 Or a range consisting of any two of them.

[0066] The raw material information used in the following specific embodiments may be as follows, but is not limited to: Polyketone resin: grade M330F, manufactured by Hyosung, South Korea; POE-g-MAH: Grade N493, manufactured by Dow Chemical Company, USA; SEBS-g-MAH: Grade FG1901, manufactured by Kraton Technologies, USA; MBS: The grades are M521, M711, and M722, and the manufacturer is Kanekachi, Japan. Ferric oxide magnetic powder: TY031847, sourced from Lingchuan Mineral Products Processing Plant, Lingshou County; Rare earth neodymium iron boron magnetic powder: NT066314, sourced from Lingchuan Mineral Products Processing Plant, Lingshou County.

[0067] Example 1 This embodiment provides a method for preparing a magnetically conductive polyketone material, including the following steps: (1) After ball milling the ferric oxide magnetic powder, it was passed through a 200-mesh sieve. Then, the sieved magnetic powder and N-methylpyrrolidone were weighed at a mass ratio of 1:4, mixed, and ultrasonically dispersed for 40 min to obtain a dispersion. 7% of the mass of the sieved magnetic powder was added to the dispersion, and the pH was adjusted to 8.0 with triethanolamine. The mixture was then kept at 130℃ for 4 h. After the reaction was completed, the solid phase was collected by vacuum filtration, dried in an oven at 80℃, and imidized at 220℃ for 2.5 h under nitrogen protection to obtain magnetic powder coated with a polyimide layer.

[0068] Then, magnetic powder coated with polyimide layer and anhydrous ethanol were weighed at a mass ratio of 1:5. Then, 3% of titanate coupling agent GR-201 (based on the mass of the magnetic powder after sieving) was added. The mixture was stirred at 70℃ for 2 h. The mixture was filtered and the solid phase was washed 2-3 times with anhydrous ethanol. The solid phase was collected and dried in a vacuum oven at 60℃ to obtain modified magnetic powder.

[0069] (2) Weigh out 100 parts by weight of polyketone resin, 50 parts by weight of modified magnetic powder, 0.8 parts by weight of EBS, 0.4 parts by weight of PETS, 5 parts by weight of POE-g-MAH, 0.2 parts by weight of antioxidant 1010 and 0.2 parts by weight of antioxidant 168, and set aside. Add polyketone resin, EBS, PETS, POE-g-MAH, antioxidant 1010 and antioxidant 168 into a high-speed mixer and mix at 90°C and 400 rpm for 7 min to obtain a mixture.

[0070] The mixture was fed into the main feed port of the twin-screw extruder, and the modified magnetic powder was fed into the side feed port. The extrusion temperatures of the twin-screw extruder were 215℃, 240℃, 240℃, 240℃, 230℃, 230℃, 230℃, 230℃, 235℃, and 240℃, respectively. The main extruder speed was 350 rpm, and the screw length-to-diameter ratio was 42:1. After water-cooled granulation, the mixture was dried in an oven at 90℃ for 5 hours.

[0071] The dried granules were magnetized under a magnetic field strength of 1000 kA / m to obtain a magnetically conductive polyketone material.

[0072] Example 2 group The preparation method of the magnetically conductive polyketone material in this set of examples refers to that in Example 1, the only difference is that the amount of modified magnetic powder used in step (2) is different. The rest is the same as in Example 1. The specific differences are as follows: Example 2a: The amount of modified magnetic powder used was 60 parts; Example 2b: The amount of modified magnetic powder used was 70 parts; Example 2c: The amount of modified magnetic powder used was 40 parts; Example 2d: The amount of modified magnetic powder used was 85 parts.

[0073] Example 3 Group The preparation method of the magnetically conductive polyketone material in this set of examples refers to that in Example 1, the only difference is that the type of toughening agent is different in step (2). The rest are the same as in Example 1. The specific differences are as follows: Example 3a: MBS (M711) was used to replace POE-g-MAH in Example 1 by weight; Example 3b: SEBS-g-MAH was used as an equal weight substitute for POE-g-MAH in Example 1.

[0074] Example 4 This embodiment refers to the preparation method of the magnetic polyketone material in Example 1. The only difference is that in step (1), the type of magnetic powder and the sieve mesh size are different. All other aspects are the same as in Example 1. The specific differences are as follows: The magnetic powder in this embodiment is rare earth neodymium iron boron magnetic powder, which is ball-milled and then passed through a 300-mesh sieve.

[0075] Example 5 This embodiment refers to the preparation method of the magnetically conductive polyketone material in Example 4, the only difference being that the amount of modified magnetic powder used in step (2) is different, and the rest is the same as in Example 4. The specific differences are as follows: In this embodiment, the amount of modified magnetic powder used is 70 parts.

[0076] Example 6 group The preparation method of the magnetically conductive polyketone material in this set of examples refers to that in Example 3a, the only difference is that the type of MBS is different in step (2). The rest is the same as in Example 3a. The specific differences are as follows: Example 6a: MBS is M521, butadiene content is 55%; Example 6b: MBS is M722, and butadiene content is 60%.

[0077] Example 7 group The preparation method of the magnetically conductive polyketone material in this set of examples refers to that in Example 1, the only difference is that the amount of polyamic acid used in step (1) is different. The rest are the same as in Example 1. The specific differences are as follows: Example 7a: The amount of polyamic acid used was 6.5% of the mass of the sieved magnetic powder; Example 7b: The amount of polyamic acid used was 7.5% of the mass of the sieved magnetic powder.

[0078] Comparative Example 1 Comparative Example 1 refers to the preparation method of magnetic polyketone material in Example 1, except that in step (1), the magnetic powder was not modified, and in step (2), 50 parts by weight of ball-milled magnetic powder that passed through a 200-mesh sieve was directly used to replace the modified magnetic powder to prepare magnetic polyketone material.

[0079] Comparative Example 2 Comparative Example 2 refers to the preparation method of the magnetically conductive polyketone material in Example 1, except that in step (1), only the surface of the magnetic powder is coated with a polyimide layer and no titanate coupling agent layer is coated; in step (2), 50 parts by weight of magnetic powder coated with a polyimide layer are directly used to replace the modified magnetic powder to prepare the magnetically conductive polyketone material.

[0080] Comparative Example 3 Groups The comparative example in this group refers to the preparation method of the magnetically conductive polyketone material in Example 1. The only difference is that the amount of modified magnetic powder used in step (2) is different. All other aspects are the same as in Example 1. The specific differences are as follows: Comparative Example 3a: The amount of modified magnetic powder used was 35 parts; Comparative Example 3b: The amount of modified magnetic powder used was 90 parts.

[0081] Comparative Example 4 This comparative example refers to the preparation method of the magnetically conductive polyketone material in Example 1, the only difference being that the preparation method of the modified magnetic powder is different in step (1), the rest is the same as in Example 1, the specific differences are as follows: The modified magnetic powder used in this comparative example was prepared according to steps 1) to 3) of Example 1 in Publication No. CN109206894A.

[0082] Comparative Example 5 This comparative example refers to the preparation method of the magnetic polyketone material in Example 1, the only difference being that the extrusion temperature setting of the twin-screw extruder is different in step (2), and the rest is the same as in Example 1. The specific differences are as follows: The extrusion temperatures of the twin-screw extruder in this comparative example are 210℃, 250℃, 250℃, 250℃, 220℃, 220℃, 220℃, 230℃, and 250℃, respectively.

[0083] Experimental Example The following properties of the magnetically conductive polyketone materials prepared in different embodiments and comparative examples were tested, and the test results are shown in Table 1.

[0084] 1. Tensile strength: The tensile strength was tested in accordance with GB / T 1040 "Determination of tensile properties of plastics - Part 1: General". 2. Impact strength: The impact strength was tested in accordance with GB / T 1843 "Determination of Impact Strength of Plastic Cantilever Beams"; 3. Melt flow index: The melt flow index was tested in accordance with GB / T 3682 "Determination of melt mass flow rate and melt volume flow rate of thermoplastics"; 4. Remanence: Remanence was tested according to GB / T 3217 "Methods for Testing Magnetic Materials with Permanent Magnets (Hard Magnets)"; 5. Intrinsic coercivity: The intrinsic coercivity is tested according to GB / T 3217 "Methods for Testing Magnetic Samples of Permanent Magnet (Hard Magnetic) Materials"; 6. Maximum magnetic energy product: The maximum magnetic energy product shall be tested in accordance with GB / T 3217 "Methods for Magnetic Samples of Permanent Magnet (Hard Magnetic) Materials"; If the above tests use specimens, they are all prepared by injection molding machine according to conventional injection molding process.

[0085] Table 1 Performance test results of different magnetically permeable polyketone materials

[0086] The test results above show that the present invention uses modified magnetic powder with a double-layer coating of polyimide and titanate coupling agent, and combines it with polyketone resin with suitable crystallinity to achieve uniform dispersion of the modified magnetic powder in the polyketone resin, thereby obtaining a magnetically conductive polyketone material with both good mechanical properties and processing fluidity. Furthermore, by adding an appropriate amount of toughening agent, not only is the impact resistance of the material effectively improved and the generation of microcracks suppressed, but the micro-interfacial bonding performance between the polyketone resin and the modified magnetic powder is also enhanced, thereby further improving the magnetic properties of the magnetically conductive polyketone material.

[0087] The test results of Example 1 and Comparative Examples 1-2 show that when the magnetic powder is not modified, the mechanical properties, processing fluidity and magnetism of the obtained magnetically conductive polyketone material are significantly reduced; when only the magnetic powder is coated with a polyimide layer, although all properties are improved compared to Comparative Example 1, the improvement is limited.

[0088] The test results from Examples 1, 2 and 3 show that the amount of modified magnetic powder affects the mechanical properties, processing fluidity and magnetic properties of the magnetically conductive polyketone material. When the amount of modified magnetic powder is too low, the magnetism is insufficient. When the amount of modified magnetic powder is too high, it is not conducive to the impact resistance of the magnetically conductive polyketone material, and it will also lead to poor processing fluidity.

[0089] The test results of Example 1 and Comparative Example 4 show that the polyimide layer and titanate coupling agent layer coated on the surface of the modified magnetic powder in the embodiments of the present invention are more conducive to the uniform dispersion of the modified magnetic powder in the polyketone resin material, ensuring the mechanical properties, magnetic properties and processing flowability of the magnetically conductive polyketone material.

[0090] The test results from Example 1 and Comparative Example 5 show that the twin-screw extrusion temperature setting used in the embodiments of the present invention is more conducive to ensuring the uniform dispersion of magnetic powder in polyketone material and can effectively avoid the degradation of polyketone material. If the extrusion temperature setting is unreasonable, it will not only be detrimental to the dispersion of magnetic powder, but may also cause the degradation of polyketone material, resulting in a significant reduction in the mechanical properties of the magnetically conductive polyketone material.

[0091] The test results from Examples 1 and 3 show that when MBS and SEBS-g-MAH are used as toughening agents, the tensile strength and impact strength of the obtained magnetic polyketone material are improved compared to Example 1, and MBS has a more significant effect on improving the impact strength of the magnetic polyketone material. Furthermore, as a toughening agent, MBS helps to improve the microscopic interfacial bonding between the modified magnetic powder and the polyketone material, which can further improve the magnetic properties of the magnetic polyketone material.

[0092] The test results from Examples 3a and 6 show that using MBS with a certain butadiene content is more helpful in balancing the impact resistance and magnetic properties of the magnetically conductive polyketone material.

[0093] The test results from Examples 3a and 7 show that an appropriate amount of polyamic acid is more conducive to balancing the strength and magnetic properties of the magnetically conductive polyketone material.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetically conductive polyketone material, characterized in that, The raw materials for preparation include the following components by weight: 100 parts of polyketone resin, 40-85 parts of modified magnetic powder, 2.5-10.5 parts of toughening agent and 0.5-2 parts of lubricant; The modified magnetic powder includes a magnetic powder core and a polyimide layer and a titanate coupling agent layer that are sequentially coated on the surface of the magnetic powder core from the inside out. The crystallinity of the polyketone resin is 40%~55%.

2. The magnetically conductive polyketone material according to claim 1, characterized in that, The polyketone resin has at least one of the following characteristics: (1) The melt flow rate of the polyketone resin at 240℃ and 2.16kg is 55~65 g / 10 min; (2) The polyketone resin is obtained by copolymerization of carbon monoxide, ethylene and propylene; the propylene content is 2 wt%~8 wt%.

3. The magnetically conductive polyketone material according to claim 1, characterized in that, The magnetic powder core includes at least one of iron tetroxide and rare earth neodymium iron boron magnetic powder.

4. The magnetically conductive polyketone material according to claim 1, characterized in that, The toughening agent includes at least one of maleic anhydride-grafted ethylene-octene copolymer, maleic anhydride-grafted styrene-ethylene-butene-styrene block copolymer, and methyl methacrylate-butadiene-styrene terpolymer.

5. The magnetically conductive polyketone material according to claim 4, characterized in that, In the methyl methacrylate-butadiene-styrene terpolymer, the butadiene content is 40 wt% to 60 wt%.

6. The magnetically conductive polyketone material according to claim 1, characterized in that, The lubricant includes at least one of N,N'-ethylene bis-stearamide, pentaerythritol stearate, zinc stearate, and polyethylene wax.

7. The method for preparing the magnetically conductive polyketone material according to any one of claims 1 to 6, characterized in that, The process includes the following steps: a mixture of polyketone resin, lubricant, toughening agent, and modified magnetic powder are fed into a twin-screw extruder through the main feed port and side feed port, respectively, for melt extrusion granulation; The temperature of the melt extrusion is 210~245℃.

8. The preparation method according to claim 7, characterized in that, The twin-screw extruder includes ten temperature zones, each with the following temperature settings: Zone 1 210~220℃, Zone 2 235~245℃, Zone 3 235~245℃, Zone 4 235~245℃, Zone 5 225~235℃, Zone 6 225~235℃, Zone 7 225~235℃, Zone 8 225~235℃, Zone 9 230~240℃, and Zone 10 235~245℃.

9. The preparation method according to claim 7, characterized in that, The preparation method of the modified magnetic powder includes the following steps: (a) Add polyamic acid to the dispersion containing unmodified magnetic powder, then adjust the pH to 7.5~8.5, keep the reaction at 120~150℃ for 3~5 h, collect the solid phase after solid-liquid separation and dry it; imidize the dried solid phase at 200~250℃ for 2~3 h to obtain magnetic powder coated with polyimide layer. (b) The magnetic powder coated with the polyimide layer is dispersed in anhydrous ethanol, a titanate coupling agent is added, and the mixture is stirred at 60-80°C for 1.5-3 h. After solid-liquid separation, the solid phase is collected and dried to obtain the modified magnetic powder.

10. The preparation method according to claim 9, characterized in that, In step (a), the mass of the polyamic acid is 5% to 10% of the mass of the unmodified magnetic powder; In step (b), the mass of the titanate coupling agent is 2% to 5% of the mass of the unmodified magnetic powder.

Images