Polyurethane-ferrite composition, preparation method thereof, injection molding method and product

Abstract

The present invention relates to polyurethane-ferrite compositions, methods of making the same, methods of injection molding, and the resulting articles. The polyurethane-ferrite composition comprises the following components or consists of the following components in percentage by mass: 3-15% of a thermosetting polyurethane prepolymer mixture, which is a combination of an isocyanate-terminated first polyurethane prepolymer with the number-average molecular weight of 10000-60000 and a hydroxyl-terminated second polyurethane prepolymer with the number-average molecular weight of 10000-60000, and the balance of ferrite; 80-96% by mass of permanent magnetic ferrite particles uniformly dispersed in the mixture and optionally subjected to surface treatment by a coupling agent; and 1-5% by mass of an auxiliary agent uniformly dispersed in the mixture, relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnetic ferrite particles and the auxiliary agent, the total mass does not include the mass of the coupling agent. A product prepared from the composition has excellent magnetic performance and mechanical performance, and can be used for manufacturing rotors with larger sizes.

Description

Technical Field

[0001] The present invention generally relates to the field of composite materials, and in particular to a polyurethane-ferrite composition which can be used to manufacture plastic magnets such as plastic magnet rotors for motors, a preparation method thereof, an injection molding method thereof, and a product obtained therefrom. Background Art

[0002] Plastic magnets are generally made of organic macromolecular (polymer) resin and inorganic magnetic powder. Nylon is widely used as a plastic magnet binder due to its good processing properties. Currently, the main plastic magnets used are nylon / ferrite plastic magnets.

[0003] However, the applicant has found that for common nylon / ferrite plastic magnets, the nylon solidifies quickly during the injection molding process, resulting in too short an orientation time for the ferrite particles and the inability to evenly mix the additives, so that the magnetic properties of the rotor after molding do not reach the expected effect. In addition, the nylon used is a thermoplastic resin, which has insufficient high temperature resistance and mechanical properties. Therefore, when the nylon / ferrite plastic magnet is injection molded into a motor rotor with a larger size (e.g., a diameter of more than 130 mm), the resulting rotor is prone to cracking or breaking due to the high temperature generated during long-term operation (high-speed rotation), so it can only be made into a rotor with a smaller size (e.g., a diameter of less than 130 mm).

[0004] Therefore, it is hoped to provide a polymer-ferrite composition that can overcome the above-mentioned disadvantages of the prior art nylon / ferrite plastic magnets, and the products made therefrom have excellent magnetic and mechanical properties and can be made into rotors of larger sizes (for example, with a diameter of more than 130 mm). Summary of the invention

[0005] The present invention is made in view of the above problems existing in the prior art.

[0006] In a first aspect, the present invention provides a polyurethane-ferrite composition comprising or consisting of:

[0007] (1) 3-15% by mass of a thermosetting polyurethane prepolymer mixture, wherein the thermosetting polyurethane prepolymer mixture is a combination (e.g., a mixture) of:

[0008] a first isocyanate-terminated polyurethane prepolymer having a number average molecular weight of 10,000-60,000, such as 35,000-45,000, such as 38,000-44,000; and

[0009] A second hydroxyl-terminated polyurethane prepolymer having a number average molecular weight of 10,000-60,000, such as 35,000-45,000, such as 38,000-44,000;

[0010] (2) 80-96% by mass of permanent ferrite particles, which are optionally surface-treated with a coupling agent and are uniformly dispersed in the thermosetting polyurethane prepolymer mixture;

[0011] (3) 1-5% by mass of an auxiliary agent uniformly dispersed in the thermosetting polyurethane prepolymer mixture, preferably, the auxiliary agent is a plasticizer and / or a lubricant,

[0012] Relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnetic ferrite particles, and the auxiliary agent, the total mass does not include the mass of the coupling agent.

[0013] In a second aspect, the present invention provides a method for preparing the polyurethane-ferrite composition of the first aspect of the present invention, comprising the steps of:

[0014] Providing permanent magnet ferrite particles, and optionally, surface-treating the permanent magnet ferrite particles with a coupling agent to obtain surface-treated permanent magnet ferrite particles;

[0015] providing a first component including a first polyurethane prepolymer and optionally a solvent;

[0016] providing a second component comprising a second polyurethane prepolymer and optionally a solvent;

[0017] dispersing optionally treated permanent magnetic ferrite particles in one of the first component and the second component to obtain a first mixture;

[0018] The other of the first component and the second component and an adjuvant are mixed with the first mixture.

[0019] In a third aspect, the present invention provides an injection molding method comprising the steps of:

[0020] The polyurethane-ferrite composition of the first aspect of the present invention or the polyurethane-ferrite composition prepared by the method of the second aspect of the present invention is injection molded in the presence of a magnetic field that orients the permanent ferrite contained in the composition.

[0021] In a fourth aspect, the present invention provides an article prepared by the method of the third aspect of the present invention.

[0022] The applicant has found that by using a first isocyanate-terminated polyurethane prepolymer with a number average molecular weight of 10,000-60,000, such as 35,000-45,000, such as 38,000-44,000 and a second hydroxyl-terminated polyurethane prepolymer with a number average molecular weight of 10,000-60,000, such as 35,000-45,000, such as 38,000-44,000, the reaction between the two is relatively slow at room temperature, thereby allowing sufficient time to evenly disperse the permanent ferrite particles, and then when the prepared composition is injection molded into an article, sufficient time is allowed for the ferrite particles to be better oriented under the action of the oriented magnetic field, so that the magnetic properties of the obtained article are improved compared with those prepared using other polymers such as nylon and permanent ferrite particles, and the improved dispersion uniformity can also improve the mechanical properties. In addition, since a thermosetting polyurethane prepolymer mixture is used (i.e., the average NCO functionality of the first isocyanate-terminated polyurethane prepolymer and / or the average OH functionality of the second hydroxyl-terminated polyurethane prepolymer is greater than 2, or an isocyanate with a functionality greater than 2 and / or a hydroxyl compound with a functionality greater than 2 is used in the preparation of the first isocyanate-terminated polyurethane prepolymer and / or the preparation of the second hydroxyl-terminated polyurethane prepolymer, so that the polyurethane prepolymer mixture can finally react to form a cross-linked structure), the polyurethane in the final product is cross-linked, so that the obtained product has good high temperature resistance and mechanical properties, and can prepare rotors of larger sizes (for example, with a diameter of more than 130 mm), and the rotor is not easy to crack or break due to the high temperature generated during long-term operation (high-speed rotation). BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution of the present invention, the following will briefly describe the drawings required for describing the embodiments. It should be understood that these drawings are only for the convenience of technicians to understand the present invention more easily, and are not intended to limit the scope of the present invention.

[0024] Figure 1 The comparison of the surface magnetic curves of the rotor prepared using the polyurethane / ferrite composition of Example 1 and the nylon / ferrite plastic magnetic rotor of Comparative Example 1 is shown. DETAILED DESCRIPTION

[0025] In order to make the invention purpose, technical solution and beneficial technical effect of the present application clearer, the present application will be described in detail below. It should be noted that the various aspects, features, implementation methods and advantages described in the present application may be compatible and / or may be combined together.

[0026] Unless otherwise specified, the meanings of the technical terms in this specification are the same as those generally understood by those skilled in the art.

[0027] Relational terms such as “first” and “second” are used merely to distinguish one element, component or method step from another with the same name, but do not necessarily require or imply any such actual relationship or order between these elements, components or method steps.

[0028] The present invention relates to a polyurethane-ferrite composition, a preparation method thereof, an injection molding method thereof, and a product obtained therefrom.

[0029] The present invention will be described in detail below.

[0030] Polyurethane-ferrite composite

[0031] In a first aspect, the present invention provides a polyurethane-ferrite composition comprising or consisting of:

[0032] (1) 3-15% by mass of a thermosetting polyurethane prepolymer mixture, wherein the thermosetting polyurethane prepolymer mixture is a combination (e.g., a mixture) of:

[0033] a first isocyanate-terminated polyurethane prepolymer having a number average molecular weight of 10,000-60,000, such as 35,000-45,000, such as 38,000-44,000; and

[0034] A second hydroxyl-terminated polyurethane prepolymer having a number average molecular weight of 10,000-60,000, such as 35,000-45,000, such as 38,000-44,000;

[0035] (2) 80-96% by mass of permanent ferrite particles, which are optionally surface-treated with a coupling agent and are uniformly dispersed in the thermosetting polyurethane prepolymer mixture;

[0036] (3) 1-5% by mass of an auxiliary agent uniformly dispersed in the thermosetting polyurethane prepolymer mixture, preferably, the auxiliary agent is a plasticizer and / or a lubricant,

[0037] Relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnetic ferrite particles, and the auxiliary agent, the total mass does not include the mass of the coupling agent.

[0038] In the following, unless otherwise specified, when referring to the mass content of the thermosetting polyurethane prepolymer mixture, the permanent magnet ferrite particles and the additives in the polyurethane-ferrite composition, the mass content refers to the content relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnet ferrite particles, and the additives (that is, the total mass does not include the mass of the coupling agent) (hereinafter, for the sake of simplicity, the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnet ferrite particles, and the additives is sometimes referred to as the total mass of the composition).

[0039] In an embodiment, the polyurethane-ferrite composition comprises 3-15% by mass, for example 6-10% by mass, of the thermosetting polyurethane prepolymer mixture, relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnetic ferrite particles, and the auxiliary agent; for example, the amount of the thermosetting polyurethane prepolymer mixture, relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnetic ferrite particles, and the auxiliary agent, can be: 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 15.0% by mass, or a range limited by any two of them. When the amount of the thermosetting polyurethane prepolymer mixture is 3% by mass or more, it has a good bonding effect on the permanent magnet ferrite particles. When the amount of the thermosetting polyurethane prepolymer mixture is 15% by mass or less, the addition of the non-magnetic material does not substantially affect or weaken the contribution of the permanent magnet ferrite particles to the magnetism due to the dilution of the permanent magnet ferrite particles. When the amount of the thermosetting polyurethane prepolymer mixture is 6-10% by mass, the bonding effect on the permanent magnet ferrite particles is further improved, and the influence or weakening effect on the magnetism of the permanent magnet ferrite particles is further reduced.

[0040] In the present application, if there is no special explanation, when the term "thermosetting polyurethane prepolymer mixture" or other expressions with the same meaning is used, it means that the average NCO functionality of the first polyurethane prepolymer of terminal isocyanate type is greater than 2, and / or the average OH functionality of the second polyurethane prepolymer of terminal hydroxyl type is greater than 2 (for example: the average NCO functionality of the first polyurethane prepolymer of terminal isocyanate type is greater than 2 and the average OH functionality of the second polyurethane prepolymer of terminal hydroxyl type is equal to 2; or the average NCO functionality of the first polyurethane prepolymer of terminal isocyanate type is greater than 2 and the average OH functionality of the second polyurethane prepolymer of terminal hydroxyl type is equal to 2; The average NCO functionality is equal to 2 and the average OH functionality of the terminal hydroxyl type second polyurethane prepolymer is greater than 2; or the average NCO functionality of the terminal isocyanate type first polyurethane prepolymer is greater than 2 and the average OH functionality of the terminal hydroxyl type second polyurethane prepolymer is greater than 2). In other words, isocyanates with a functionality greater than 2 and / or hydroxyl compounds with a functionality greater than 2 are used in the preparation of the terminal isocyanate type first polyurethane prepolymer and / or the preparation of the terminal hydroxyl type second polyurethane prepolymer, so that the polyurethane prepolymer mixture can finally react to form a cross-linked structure.

[0041] In an embodiment, the number average molecular weight of the first polyurethane prepolymer is 10000-60000, such as 35000-45000, such as 38000-44000, such as 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, 30000, 31000, 32000, 33000, 34000, 35000, 36000, 37000, 38000, 39000, 40000, 41000, 42000, 43000, 44000, 45000, 46000, 47000, 48000, 49000, 50000, 51000, 52000, 53000, 54000, 55000 000, 1000, 32000, 33000, 34000, 35000, 36000, 37000, 38000, 39000, 40000, 41000, 42000, 43000, 44000, 45000, 46000, 47000, 48000, 49000, 50000, 51000, 52000, 53000, 54000, 55000, 56000, 57000, 58000, 59000, 60000, or a range limited by any two thereof.

[0042] In an embodiment, the number average molecular weight of the second polyurethane prepolymer is 10000-60000, such as 35000-45000, such as 38000-44000, such as 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, 30000, 31000, 32000, 33000, 34000, 35000, 36000, 37000, 38000, 39000, 40000, 41000, 42000, 43000, 44000, 45000, 46000, 47000, 48000, 49000, 50000, 51000, 52000, 53000, 54000 000, 1000, 32000, 33000, 34000, 35000, 36000, 37000, 38000, 39000, 40000, 41000, 42000, 43000, 44000, 45000, 46000, 47000, 48000, 49000, 50000, 51000, 52000, 53000, 54000, 55000, 56000, 57000, 58000, 59000, 60000, or a range limited by any two thereof.

[0043] Unless otherwise specified, the number average molecular weight described for each polyurethane prepolymer in this application is measured by gel permeation chromatography (GPC).

[0044] The applicant has found that by using a first polyurethane prepolymer with a number average molecular weight of 10,000-60,000, such as 35,000-45,000, such as 38,000-44,000 and a second polyurethane prepolymer with a number average molecular weight of 10,000-60,000, such as 35,000-45,000, such as 38,000-44,000, the reaction between the two is relatively slow at room temperature, thereby allowing sufficient time to evenly disperse the permanent ferrite particles, and then when the prepared composite material is injection molded into an article, sufficient time is allowed for the ferrite particles to be better oriented under the action of the oriented magnetic field, so that the magnetic properties of the obtained product are improved compared with those of the product prepared using other polymers such as nylon and permanent ferrite particles, and the improved dispersion uniformity can also improve the mechanical properties. In addition, since a thermosetting polyurethane prepolymer mixture is used (those skilled in the art will understand that this means that the average NCO functionality of the first polyurethane prepolymer of terminal isocyanate type and the average OH functionality of the second polyurethane prepolymer of terminal hydroxyl type are greater than 2, or an isocyanate with a functionality greater than 2 and / or a hydroxyl compound with a functionality greater than 2 is used in the preparation of the first polyurethane prepolymer of terminal isocyanate type and / or the preparation of the second polyurethane prepolymer of terminal hydroxyl type, so that the polyurethane prepolymer mixture can finally react to form a cross-linked structure), the polyurethane in the final product is cross-linked, and the cross-linked structure gives the obtained product better high temperature resistance and mechanical properties, so that a rotor with a larger size (for example, a diameter of more than 130 mm) can be prepared, and the rotor is not easy to crack or break due to the high temperature generated during long-term operation (high-speed rotation) (for example, under the usual operating speed and load conditions of the motor).

[0045] In an embodiment, the amount of the first polyurethane prepolymer relative to the total mass of the thermosetting polyurethane prepolymer mixture (i.e., the total mass of the mixture of the first polyurethane prepolymer and the second polyurethane prepolymer) is not particularly limited, and may be, for example, 15-85% by mass, for example 25-75% by mass, for example 35-65% by mass, for example 45-55% by mass, for example 48-50% by mass, for example 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, 101%, 102%, 103%, 104%, 105%, 106%, 107%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85% mass, or a range limited by any two thereof.

[0046] In an embodiment, the first polyurethane prepolymer can be prepared by reacting an aromatic and / or alicyclic, for example, aromatic, first diisocyanate with an aliphatic first polyalkylene glycol; and then reacting the reaction product with a mixture of an aliphatic first alkylene glycol chain extender and an optional first polyol, for example, a triol, as a crosslinking agent.

[0047] Alternatively, the first polyurethane prepolymer can be prepared by reacting an aromatic and / or alicyclic, for example, aromatic, first diisocyanate with an aliphatic first polyalkylene glycol; then reacting the reaction product with an aliphatic first alkylene glycol chain extender, and then optionally reacting with a first polyol, for example, a triol, as a crosslinking agent (i.e., reacting with the first polyol, for example, a triol, if the first polyol as a crosslinking agent is present).

[0048] Preferably, the first polyurethane prepolymer is prepared by reacting an aromatic first diisocyanate with an aliphatic first polyalkylene glycol and then reacting the reaction product with a mixture of an aliphatic first alkylene glycol chain extender and a first trihydroxy compound as a crosslinking agent.

[0049] Those skilled in the art will appreciate that, in terms of the molar equivalents of NCO groups and OH groups, the total molar amount of OH groups contained in the first polyalkylene glycol, the first alkylene glycol chain extender, and the optionally used first polyol compound containing three or more hydroxyl groups is less than the amount of NCO groups contained in the first diisocyanate compound used.

[0050] Preferably, the total amount of hydroxyl groups contained in the first polyalkylene glycol, the first alkylene glycol chain extender and the optional first polyol is 0.4-0.98 mol, preferably 0.45-0.70 mol, for example 0.50-0.60 mol, relative to 1 mol of the isocyanate group contained in the first diisocyanate, and can be, for example, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.70, 0.80, 0.90, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25 .59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98 or a range defined by any two of them.

[0051] In an embodiment, the second polyurethane prepolymer can be prepared by reacting an aromatic and / or alicyclic, e.g., aromatic and alicyclic, second diisocyanate compound with an aliphatic second polyalkylene glycol, and then reacting the reaction product with an aliphatic second alkylene glycol chain extender and optionally an aliphatic second polyhydroxy compound having three or more hydroxyl groups, e.g., a trihydroxy compound.

[0052] Alternatively, the second polyurethane prepolymer can be prepared by reacting an aromatic and / or alicyclic, e.g., aromatic and alicyclic, second diisocyanate compound with an aliphatic second polyalkylene glycol, and then reacting the reaction product with an aliphatic second alkylene glycol chain extender, and then optionally reacting with a second polyol, e.g., a triol, as a crosslinking agent (i.e., reacting with a second polyol, e.g., a triol, if a second polyol as a crosslinking agent is present).

[0053] Preferably, the second polyurethane prepolymer is prepared by reacting aromatic and alicyclic second diisocyanates with second polyalkylene glycols and then reacting the reaction product with a second alkylene glycol chain extender (in this case, no second polyol is used).

[0054] Those skilled in the art will appreciate that, in terms of the molar equivalents of NCO groups and OH groups, the total molar amount of OH groups contained in the second polyalkylene glycol, the second alkylene glycol chain extension, and the optionally used second polyol containing three or more hydroxyl groups is greater than the amount of NCO groups contained in the second diisocyanate compound used.

[0055] Preferably, the total amount of hydroxyl groups contained in the second polyalkylene glycol, the second alkylene glycol chain extender and the optional second polyol, relative to 1 mol of the isocyanate group contained in the second diisocyanate, can be, for example, 1.02-1.25 mol, for example, 1.05-1.15 mol, for example, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.21, 1.22, 1.23, 1.24, 1.25 or the range defined by any two thereof.

[0056] The first diisocyanate compound and the second diisocyanate compound may be the same or different and may each independently be, for example, one or more of the following: an aromatic diisocyanate, such as toluene diisocyanate (TDI) (e.g., 2,3-toluene diisocyanate, 2,4-toluene diisocyanate, 2,5-toluene diisocyanate, 2,6-toluene diisocyanate, or any combination thereof), diphenylmethane diisocyanate (MDI) (e.g., 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'- diphenylmethane diisocyanate, in particular 4,4'-diphenylmethane diisocyanate), naphthalene diisocyanate (for example 1,5-naphthalene diisocyanate), p-phenylene diisocyanate (1,4-phenylene diisocyanate), xylylene diisocyanate (XDI, for example m-XDI, p-XDI, or any combination thereof), 1,3-bis(1-isocyanato-1-methylethyl)benzene (also known as tetramethyl meta-xylylene diisocyanate, TMXDI), dimethyl biphenyl diisocyanate (TODI, for example 3,3'-dimethyl-4, 4'-biphenyl diisocyanate), polymethylene polyphenyl isocyanate (also known as crude MDI), TDI dimer, TDI trimer; cycloaliphatic diisocyanates, for example, isophorone diisocyanate (IPDI, also known as 3-isocyanatomethylene-3,5,5-trimethylcyclohexyl isocyanate or 1,3,3-trimethyl-5-isocyanato-1-isocyanatomethylcyclohexane), dicyclohexylmethane diisocyanate (4,4'-dicyclohexylmethane diisocyanate, also known as HMDI or hydrogenated MDI), 1,4- Cyclohexane diisocyanate, cyclohexane dimethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate (e.g., 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, and mixtures thereof), norbornane diisocyanate (e.g., 2,5-bis(isocyanate methyl)bicyclo[2.2.1]heptane, 2,6-bis(isocyanate methyl)bicyclo[2.2.1]heptane, or mixtures thereof), methylcyclohexyl diisocyanate; but not limited thereto.

[0057] For example,

[0058] (1) the first diisocyanate can be an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above), and the second isocyanate can be an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above); or

[0059] (2) the first diisocyanate may be an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above), and the second isocyanate may be an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above);

[0060] (3) the first diisocyanate may be an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above), and the second isocyanate may be a mixture of an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above) and an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above);

[0061] (4) the first diisocyanate can be an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above), and the second isocyanate can be an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above); or

[0062] (5) the first diisocyanate may be an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above), and the second isocyanate may be an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above);

[0063] (6) the first diisocyanate may be an alicyclic diisocyanate (e.g., one or more of the aromatic diisocyanates described above), and the second isocyanate may be a mixture of an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above) and an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above);

[0064] (7) the first diisocyanate may be a mixture of an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above) and an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above), and the second isocyanate may be an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above); or

[0065] (8) the first diisocyanate may be a mixture of an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above) and an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above), and the second isocyanate may be an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above);

[0066] (9) The first diisocyanate may be a mixture of an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above) and an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above), and the second isocyanate may be a mixture of an aromatic diisocyanate (e.g., one or more of the aromatic diisocyanates described above) and an alicyclic diisocyanate (e.g., one or more of the alicyclic diisocyanates described above).

[0067] Those skilled in the art will appreciate that in each of the above situations (1) to (9), when the first diisocyanate and the second diisocyanate both use / include aromatic diisocyanates, the aromatic diisocyanate in the first diisocyanate and the aromatic diisocyanate in the second diisocyanate may be the same or different; when the first diisocyanate and the second diisocyanate both use / include alicyclic diisocyanates, the alicyclic diisocyanate in the first diisocyanate and the alicyclic diisocyanate in the second diisocyanate may be the same or different; when the first diisocyanate and the second diisocyanate both use / include a mixture of aromatic diisocyanates and alicyclic diisocyanates, the first diisocyanate and the second diisocyanate may be the same or different. The mixture of aromatic diisocyanate and alicyclic diisocyanate in the diisocyanate and the mixture of aromatic diisocyanate and alicyclic diisocyanate in the second diisocyanate may be the same or different, for example, the aromatic diisocyanate in the first diisocyanate and the aromatic diisocyanate in the second diisocyanate may be the same or different, the alicyclic diisocyanate in the first diisocyanate and the alicyclic diisocyanate in the second diisocyanate may be the same or different, and the mass ratio of the aromatic diisocyanate to the alicyclic diisocyanate in the first diisocyanate and the mass ratio of the aromatic diisocyanate to the alicyclic diisocyanate in the second diisocyanate may be the same or different.

[0068] When the first diisocyanate is a mixture of an aromatic diisocyanate and an alicyclic diisocyanate, the amount of the alicyclic diisocyanate in the first diisocyanate may be 0.1-10 mol, for example, 0.5-2.0 mol, for example, 0.75-1.0 mol, for example, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.75, 0.80, 0.90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550 , 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0 ...

[0069] When the second diisocyanate is a mixture of an aromatic diisocyanate and an alicyclic diisocyanate, the amount of the alicyclic diisocyanate in the second diisocyanate may be 0.1-10 mol, for example, 0.5-2.0 mol, for example, 0.75-1.0 mol, for example, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.75, 0.80, 0.90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480 , 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0 ...

[0070] In a preferred embodiment, the first diisocyanate is toluene diisocyanate.

[0071] In a preferred embodiment, the second diisocyanate is toluene diisocyanate, isophorone diisocyanate or a mixture thereof, for example, a mixture of toluene diisocyanate and isophorone diisocyanate (for example, relative to the total molar number of the mixture of toluene diisocyanate and isophorone diisocyanate as the second diisocyanate as 1 mole, the amount of toluene diisocyanate can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 0.96, 0.97, 0.98, 0.99 mole, or a range limited by any two of them).

[0072] In a preferred embodiment, when the second diisocyanate is a mixture of toluene diisocyanate and isophorone diisocyanate, the amount of isophorone diisocyanate is 0.1-10 mol, preferably 0.5-2.0 mol, preferably 0.75-1.0 mol, for example, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.6 0, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0 mole, or a range defined by any two of them.

[0073] The first polyalkylene glycol (sometimes referred to herein as the first polyether glycol) and the second polyalkylene glycol (sometimes referred to herein as the second polyether glycol) may be the same as or different from each other and may each independently include or be, for example, one or more of the following: polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol-propylene glycol copolymer (wherein the molar ratio of ethylene glycol to propylene glycol units may be, for example, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2.5:1, 2:1, 1.5:1, 1.2:1, 1.0:1, 1:1.2, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10), polyethylene glycol-butylene glycol copolymer (wherein the molar ratio of ethylene glycol units to butylene glycol units may be, for example, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2.5:1, 2:1, 1.5:1, 1.2:1, 1.0:1, 1:1.2, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10), The ratio of propylene glycol to butylene glycol can be, for example, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2.5:1, 2:1, 1.5:1, 1.2:1, 1.0:1, 1:1.2, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10), polypropylene glycol-butylene glycol copolymer (which The molar ratio of propylene glycol units to butylene glycol units can be, for example, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2.5:1, 2:1, 1.5:1, 1.2:1, 1.0:1, 1:1.2, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10).

[0074] Preferably, the number average molecular weight of the polyalkylene glycol (e.g., polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol-propylene glycol copolymer, polyethylene glycol-butylene glycol copolymer, and / or polypropylene glycol-butylene glycol copolymer, such as polypropylene glycol) may be 200-4000, such as 800-3000, such as 1000-2000, such as 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100, 4200, 4300 0, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, or a range limited by any two of them.

[0075] The polyalkylene glycol may be one type of polyalkylene glycol; a mixture of at least two polyalkylene glycols of different types; a mixture of at least two polyalkylene glycols of the same type but of different molecular weights; a mixture of at least two polyalkylene glycols of different types and at least two polyalkylene glycols of the same type but of different molecular weights; or any combination thereof.

[0076] For example, the first polyalkylene glycol and the second polyalkylene glycol may each independently be one or more selected from the following: polyethylene glycol (PEG) (e.g., polyethylene glycol-200, polyethylene glycol-300, polyethylene glycol-400, polyethylene glycol-600, polyethylene glycol-800, polyethylene glycol-1000, polyethylene glycol-1500, polyethylene glycol-2000, polyethylene glycol-3000, polyethylene glycol-4000), polypropylene glycol (PPG) (e.g., polypropylene glycol-200, polypropylene glycol-400, Polybutylene glycol-600, polybutylene glycol-800, polybutylene glycol-1000, polybutylene glycol-1500, polypropylene glycol-2000, polypropylene glycol-3000, polypropylene glycol-4000), polybutylene glycol (also known as polytetramethylene glycol, PTMG) (for example, polybutylene glycol-250, polybutylene glycol-650, polybutylene glycol-1000, polybutylene glycol-1400, polybutylene glycol-1800, polybutylene glycol-2000, polybutylene glycol-3000, polybutylene glycol-4000), but are not limited thereto.

[0077] Preferably, the amount of the first polyalkylene glycol relative to 1 mole of the first diisocyanate compound can be 0.20-0.90 mole, preferably 0.30-0.60 mole, preferably 0.4-0.5 mole, for example, it can be 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90 mole, or the range limited by any two of them.

[0078] Preferably, the second polyalkylene glycol is 0.60-0.95 mol, preferably 0.70-0.90, preferably 0.85-0.90 mol, for example, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95 mol, or a range limited by any two thereof, relative to 1 mol of the second diisocyanate compound.

[0079] The first alkylene glycol chain extender and the second alkylene glycol chain extender are the same as or different from each other, and are preferably each independently one or more of the following: ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol; propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol; 1,4-butanediol; 1,6-hexanediol.

[0080] In a preferred embodiment, the first alkylene glycol chain extender is ethylene glycol.

[0081] In a preferred embodiment, the second alkylene glycol chain extender is diethylene glycol (sometimes also referred to as diethylene glycol).

[0082] In a preferred embodiment, relative to 1 mol of the first diisocyanate compound, the first alkylene glycol chain extender is 0.005-0.30 mol, for example, 0.006-0.10 mol, for example, 0.008-0.05 mol, for example, 0.010-0.020 mol, for example, 0.010-0.015 mol, for example, 0.005, 0.006, 0.007, 0.008, 0.009, 0.010, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.020 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30 mol, or a range defined by any two of them.

[0083] In a preferred embodiment, relative to 1 mol of the second diisocyanate compound, the second alkylene glycol chain extender is 0.10-0.30 mol, for example 0.15-0.25, for example 0.20-0.25 mol, for example, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30 mol, or a range limited by any two thereof.

[0084] In an embodiment, the first polyurethane prepolymer may use the first polyol and / or the second polyurethane prepolymer may use the second polyol. For example, the first polyurethane prepolymer uses the first polyol or the second polyurethane prepolymer uses the second polyol. For example, the first polyurethane prepolymer uses the first polyol and the second polyurethane prepolymer does not use the second polyol.

[0085] In the present application, unless otherwise specified, "polyhydroxy compound" means a compound containing at least 3 hydroxyl groups in a molecule, which can be understood by those skilled in the art from the context of the present application.

[0086] The first polyol and the second polyol may be the same as or different from each other, and are each independently one or more of, for example, glycerol, trimethylolpropane, triethanolamine, triethylolpropane, pentaerythritol, but are not limited thereto.

[0087] For the first polyurethane prepolymer, when the first polyol (e.g., triol) is used, the total amount of hydroxyl groups contained in the first polyol (e.g., triol) relative to 1 mole of the first diisocyanate can be 0.02-0.50 mole, for example, 0.10-0.30 mole, for example, 0.20-0.25 mole, for example, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55 44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50 mol, or a range defined by any two of them.

[0088] For the second polyurethane prepolymer, when the second polyol (e.g., triol) is used, the total amount of hydroxyl groups contained in the second polyol (e.g., triol) relative to 1 mole of the second diisocyanate can be 0.02-0.50 mole, for example, 0.10-0.30 mole, for example, 0.20-0.25 mole, for example, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55 44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50 mol, or a range defined by any two of them.

[0089] The reaction for forming the first polyurethane prepolymer and the reaction for forming the second polyurethane prepolymer (hereinafter referred to as the first reaction and the second reaction, respectively) can be independently carried out under reaction conditions commonly used in the polyurethane field.

[0090] For example, the first reaction and the second reaction can be each independently carried out in a solvent commonly used in the polyurethane field, such as an inert solvent such as a polar aprotic solvent (e.g., acetone, butanone (methyl ethyl ketone), ethyl acetate, N,N-dimethylformamide, N-methylpyrrolidone, or a mixture thereof).

[0091] The first reaction and the second reaction can be independently carried out in the presence or absence of a catalyst. The catalyst can be a commonly used catalyst in the field of polyurethane, such as N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, N,N,N',N'-tetramethylalkylenediamine, triethylamine, N,N-dimethylbenzylamine, N-ethylmorpholine, N-methylmorpholine, N,N'-diethylpiperazine, triethanolamine, N,N-dimethylethanolamine (DMEA), pyridine, N,N'-lutidine, etc.

[0092] The first reaction and the second reaction can be independently carried out at a temperature in the range of 20-120° C. For example, the reaction temperature can be 20, 25, 30, 40, 50, 60, 70, 75, 80, 90, 100, 110, 120° C., or a range limited by any two thereof.

[0093] In an embodiment, the polyurethane-ferrite composition comprises 80-96% by mass, for example 85-92% by mass, of the permanent magnet ferrite particles which are optionally surface-treated with a coupling agent and uniformly dispersed in the thermosetting polyurethane prepolymer mixture, relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnet ferrite particles, and the auxiliary agent, and the mass of the permanent magnet ferrite particles does not include the mass of the coupling agent which is optionally included; for example, relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnet ferrite particles, and the auxiliary agent, the permanent magnet ferrite particles which are optionally surface-treated with a coupling agent are 80-96% by mass, for example 85-92% by mass. The amount of the ferrite particles (excluding the mass of the coupling agent optionally included) can be: 80.0, 80.5, 81.0, 81.5, 82.0, 82.5, 83.0, 83.5, 84.0, 84.5, 85.0, 85.5, 86.0, 86.5, 87.0, 87.5, 88.0, 88.5, 89.0, 89.5, 90.0, 90.5, 91.0, 91.5, 92.0, 92.5, 93.0, 93.5, 94.0, 94.5, 95.0, 95.5, 96.0% by mass, or the range defined by any two thereof. When the amount of the permanent magnet ferrite particles is within the above range, the obtained product has good magnetic properties and at the same time there is good bonding between the permanent magnet ferrite particles.

[0094] The permanent ferrite may be barium ferrite such as BaO·6Fe 2 O 3 Or strontium ferrite such as SrO·6Fe 2 O 3 or a mixture thereof.

[0095] The particle size of the permanent ferrite is not particularly limited. In one embodiment, the permanent ferrite may have a particle size of 0.1-250 microns, such as 0.5-10 microns, such as 1.0-5.0 microns, such as 1.0-1.5 microns (e.g. 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2. 5, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250 microns, or a range defined by any two thereof) average particle size (Dv50). In this document, unless otherwise specified, the terms Dv50, average particle size and median particle size are used interchangeably and refer to the cumulative volume distribution curve of particle size in which 50% of the volume of particles have a size lower than it and 50% of the volume of particles have a size higher than it. Dv50 can be measured using, for example, a laser scattering method. Dv50 can be measured by a particle size analyzer, such as a laser particle size analyzer.

[0096] The permanent magnetic ferrite particles may optionally be surface treated with a coupling agent.

[0097] In one embodiment, the permanent ferrite is not surface treated with a coupling agent.

[0098] In one embodiment, the permanent ferrite is surface treated with a coupling agent. The coupling agent may be, for example, one or more of the following: a silane coupling agent, such as γ-aminopropyltriethoxysilane (also known as 3-aminopropyltriethoxysilane), γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltrimethylsilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, diethylaminomethyltriethoxysilane, anilinemethyltriethoxysilane. Silane, 3-ureapropyltriethoxysilane, bis(3-trimethoxysilylpropyl)amine; titanate coupling agents, such as isopropyl triisostearate titanate, isopropyl dioleyl (dioctyl phosphate) titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl trioleyl titanate, isopropyl tri(dioctyl pyrophosphate) titanate, bis(dioctyl pyrophosphate) ethylene titanate, tetraisopropyl di(dioctyl phosphite) titanate; zirconate coupling agents, such as tetrakis(triethanolamine) zirconate, bis(diethyl citrate) dipropoxy zirconium chelate; but are not limited thereto.

[0099] The applicant has found that when the permanent magnetic ferrite particles are surface-treated with a coupling agent (e.g., a silane coupling agent such as γ-aminopropyltriethoxysilane), the permanent magnetic ferrite particles can be more uniformly dispersed in the thermosetting polyurethane prepolymer mixture under milder process conditions compared to the case where the surface treatment is not performed with a coupling agent, thereby the mechanical properties of the resulting product are better and the magnetic properties can also be further improved.

[0100] The amount of the coupling agent can be 0.5-3.0%, such as 1.0-2.0% by mass of the total mass of the thermosetting polyurethane prepolymer mixture, such as 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0% by mass, or the range defined by any two thereof. When the amount of the coupling agent is within the range, the dispersion uniformity of the permanent magnet ferrite particles can be better improved, and thus the mechanical properties and magnetic properties of the obtained product can be improved.

[0101] In an embodiment, the polyurethane-ferrite composition contains 1-5% by mass, for example 2-3% by mass, of the additive uniformly dispersed in the thermosetting polyurethane prepolymer mixture, relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnetic ferrite particles, and the additive (the total mass does not include the mass of the coupling agent). For example, relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnetic ferrite particles, and the auxiliary agent (the total mass does not include the mass of the coupling agent), the total amount of the auxiliary agent can be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0% by mass, or a range limited by any two of them.

[0102] The auxiliary agent may be an additive commonly used in the field of plastic magnets, such as a plasticizer and / or a lubricant.

[0103] The plasticizer may be one or more of the following: dioctyl terephthalate (DOTP), dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), dioctyl adipate (DOA), dibutyl sebacate (DBS), tricresyl phosphate (TCP), triphenyl phosphate (TPP), diethylene glycol dibenzoate (DEDB), but is not limited thereto.

[0104] The lubricant may be one or more of the following: zinc stearate, calcium stearate, lead stearate, barium stearate, n-butyl stearate, glyceryl monostearate, glyceryl tristearate, pentaerythritol stearate, stearic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, but is not limited thereto.

[0105] In one embodiment, when the auxiliary agent includes or is a mixture of a plasticizer and a lubricant, the amount of the plasticizer and the lubricant can be independently 0.01, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.4 5, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95, 2.05, 2 .10, 2.15, 2.20, 2.25, 2.30, 2.35, 2.40, 2.45, 2.50, 2.55, 2.60, 2.65, 2.70, 2.75, 2.80, 2.85, 2.90, 2.95, 3.05, 3.10, 3.15, 3.20, 3.25, 3.30, 3.35, 3.40, 3.45, 3.50, 3.55, 3.60, 3.65, 3.70 , 3.75, 3.80, 3.85, 3.90, 3.95, 4.05, 4.10, 4.15, 4.20, 4.25, 4.30, 4.35, 4.40, 4.45, 4.50, 4.55, 4.60, 4.65, 4.70, 4.75, 4.80, 4.85, 4.90, 4.95, 4.96, 4.97, 4.98, 4.99% by mass, or a range limited by any two of them.

[0106] In one embodiment, when a plasticizer and a lubricant are present, the lubricant may be 0.1-10 parts by mass, such as 0.2-5 parts by mass, such as 0.5-2 parts by mass, such as 1 part by mass, relative to 1 part by mass of the plasticizer, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0 parts by mass, or a range defined by any two of them.

[0107] In one embodiment, the polyurethane-ferrite composition is composed of the thermosetting polyurethane prepolymer mixture, the permanent magnetic ferrite particles which are optionally surface-treated with a coupling agent, and the auxiliary agent.

[0108] Polyurethane-ferrite composition preparation method

[0109] In a second aspect, the present invention provides a method for preparing the polyurethane-ferrite composition of the first aspect of the present invention, comprising the steps of:

[0110] Providing permanent magnet ferrite particles, and optionally, surface-treating the permanent magnet ferrite particles with a coupling agent to obtain surface-treated permanent magnet ferrite particles;

[0111] providing a first component including a first polyurethane prepolymer and optionally a solvent;

[0112] providing a second component comprising a second polyurethane prepolymer and optionally a solvent;

[0113] dispersing optionally treated permanent magnetic ferrite particles in one of the first component and the second component to obtain a first mixture;

[0114] The other of the first component and the second component and an adjuvant are mixed with the first mixture.

[0115] The above description in the section "Polyurethane-ferrite composition" also applies here.

[0116] In a preferred embodiment, the permanent magnetic ferrite particles are surface-treated with a coupling agent to obtain surface-treated permanent magnetic ferrite particles.

[0117] In a preferred embodiment, the surface treatment can be performed, for example, by dissolving the coupling agent in a solvent to obtain a treatment solution, then adding permanent magnet ferrite particles to the treatment solution and mixing evenly, and then drying to remove the solvent, thereby obtaining surface-treated permanent magnet ferrite particles.

[0118] The solvent is not particularly limited, but is preferably selected from environmentally friendly solvents with a boiling point below 100°C (thus easy to remove later), such as ethanol and acetone. The amount of the solvent is not particularly limited, as long as it can completely wet the permanent ferrite particles.

[0119] The mixing can be performed, for example, at room temperature (eg, 25° C.±5° C.).

[0120] The drying temperature is not particularly limited, and may be, for example, room temperature to 100°C, for example, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100°C or a temperature within the range defined by any two of them.

[0121] The first component may be a first polyurethane prepolymer or a solution of the first polyurethane prepolymer dissolved in a solvent (i.e., the first component is composed of the first polyurethane prepolymer and an optional solvent). The solvent used in the first component is not particularly limited as long as it can dissolve the first polyurethane prepolymer and is inert to the first polyurethane prepolymer. Preferably, the solvent may be, for example, a ketone solvent such as acetone, methyl ethyl ketone, cyclohexanone, an ester solvent such as methyl acetate, ethyl acetate, but is not limited thereto.

[0122] The second component may be a second polyurethane prepolymer or a solution of the second polyurethane prepolymer dissolved in a solvent (i.e., the second component is composed of the second polyurethane prepolymer and an optional solvent). The solvent used in the second component is not particularly limited as long as it can dissolve the second polyurethane prepolymer and is inert to the second polyurethane prepolymer. Preferably, the solvent may be, for example, a ketone solvent such as acetone, methyl ethyl ketone, cyclohexanone, an ester solvent such as methyl acetate, ethyl acetate, but is not limited thereto.

[0123] The mixing order of the ferrite with the first component and the second component is not particularly limited and can be appropriately selected as needed. In one embodiment, the optionally treated permanent magnet ferrite particles can be dispersed in the first component to obtain a first mixture; then the second component and the auxiliary agent are mixed with the first mixture (the second component and the auxiliary agent can be mixed with the first mixture together, or the second component can be mixed with the first mixture, and then the auxiliary agent is added for mixing). In another embodiment, the optionally treated permanent magnet ferrite particles can be dispersed in the second component to obtain a first mixture; then the first component and the auxiliary agent are mixed with the first mixture (the first component and the auxiliary agent can be mixed with the first mixture together, or the first component can be mixed with the first mixture, and then the auxiliary agent is added for mixing).

[0124] If a solvent is included in the first component and / or the second component, the solvent may be optionally removed after mixing. In other words, the solvent may or may not be removed.

[0125] Injection molding method

[0126] In a third aspect, the present invention provides an injection molding method comprising the steps of:

[0127] The polyurethane-ferrite composition of the first aspect of the present invention or the polyurethane-ferrite composition prepared by the method of the second aspect of the present invention is injection molded in the presence of a magnetic field that orients the permanent ferrite contained in the composition (hereinafter also referred to as an orienting magnetic field).

[0128] The injection molding is carried out in the presence of an orientation magnetic field. Preferably, the intensity of the orientation magnetic field is 0.8-4.0, for example 3.0-3.5 Tesla, for example, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0 Tesla, or a range defined by any two thereof. During the injection molding process, the direction of the magnetic field is preferably constant. During the injection molding process, the intensity of the magnetic field can be constant, variable (for example, continuously variable, intermittently variable), preferably constant.

[0129] During the injection molding process, the injection molding temperature (injection molding machine mold temperature) is set to 100-120° C., for example, it can be 100, 105, 110, 115, 120° C., or a range limited by any two of them.

[0130] During the injection molding process, the injection molding pressure is set to 1000-1800 bar, for example, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800 bar, or a range defined by any two thereof.

[0131] During injection molding, the injection temperature and the injection pressure are maintained for 60-300 seconds, for example, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300 seconds, or a time within the range defined by any two of them, and then demolding.

[0132] After demoulding is completed, the obtained product can be further machined, such as cutting, grinding, polishing, etc., if necessary.

[0133] Products

[0134] In a fourth aspect, the present invention provides an article prepared using the method of the third aspect of the present invention.

[0135] The product form of the present invention is not particularly limited. In a preferred embodiment, it can be in the form of a motor rotor. The diameter of the rotor is not particularly limited, and it can be greater than 130 mm or less than 130 mm.

[0136] By using the polyurethane-ferrite composition of the first aspect of the present invention or the polyurethane-ferrite composition prepared by the method of the second aspect of the present invention, the permanent ferrite particles in the final product are uniformly dispersed and have a good orientation, so the magnetic properties of the obtained product are improved compared with the products prepared by using other polymers such as nylon and permanent ferrite particles. And because the polyurethane in the final product is cross-linked, the mechanical properties of the obtained product are good, and it can be used to prepare rotors of larger sizes (for example, with a diameter of more than 130 mm), and the obtained rotor is not easy to crack or break due to the high temperature generated during long-term operation (high-speed rotation).

[0137] Example

[0138] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0139] raw material:

[0140] Silane coupling agent γ-aminopropyltriethoxysilane: KH550, provided by McLean, item number: A800523

[0141] Strontium ferrite permanent magnet powder (SrO·6Fe 2 O 3 ): XKYS-24F provided by Shenzhen Xingkaiyue Biotechnology Co., Ltd., average particle size 1.10-1.30 microns, remanence ≥152mT, coercivity ≥105kA / m, intrinsic coercivity ≥270kA / m, maximum magnetic energy product ≥4.3kJ / m 3 .

[0142] Toluene diisocyanate: A mixture of 80% 2,4-toluene diisocyanate and 20% 2,6-toluene diisocyanate, supplied by Maclean, Part No.: T823849

[0143] Polypropylene glycol 2000: provided by McLean, product number P815571, average (number average) molecular weight 2000

[0144] Isophorone diisocyanate: provided by Maclean, item number: I811865

[0145] Example 1

[0146] (1) Dissolve 0.6 g of silane coupling agent KH550 in 150 ml of acetone, add 920 g of strontium ferrite permanent magnet powder, stir and mix evenly at room temperature, and dry at 75°C;

[0147] (2) adding 30 g of the polyurethane component A to 920 g of the surface-treated permanent magnetic ferrite and stirring the mixture evenly, then adding 30 g of the polyurethane component B and stirring the mixture evenly, and then adding 20 g of an auxiliary agent (10 g of dioctyl terephthalate (DOTP) and 10 g of zinc stearate) and stirring the mixture evenly to obtain a polyurethane / ferrite composition 1;

[0148] The polyurethane component A is prepared as follows: 2.5 mol of toluene diisocyanate and 1 mol of polypropylene glycol 2000 (2000 g) are added, the reaction temperature is 75° C., the reaction time is 2 hours, and then cooled to 40° C., and then 0.2 mol of trimethylolpropane, 0.15 mol of triethylamine, and 0.03 mol of ethylene glycol are added, and the reaction is continued for 0.5 hours to obtain a first polyurethane prepolymer (the number average molecular weight measured by GPC is 39290). 85 ml of acetone is added and stirred evenly to obtain polyurethane component A.

[0149] The polyurethane component B is prepared as follows: 1 mol of toluene diisocyanate, 0.75 mol of isophorone diisocyanate, and 1.5 mol of polypropylene glycol 2000 as a polyether polyol are added, the reaction temperature is 75° C., the reaction time is 2 hours, and then cooled to 40° C., and then 0.4 mol of diethylene glycol is added, and the reaction is continued for 0.5 hours to obtain a second polyurethane prepolymer (the number average molecular weight measured by GPC is 42317). 350 ml of ethyl acetate is added and stirred evenly to obtain polyurethane component B.

[0150] (3) The polyurethane / ferrite composition 1 was added to an injection molding machine for injection molding. The electromagnetic field was used for orientation. The orientation field strength was 3.2 Tesla. The mold temperature of the injection molding machine was set to 105° C. and the injection pressure was set to 1500 bar. The mold was demolded after maintaining the temperature and pressure for 150 seconds.

[0151] The obtained polyurethane / ferrite magnetic material 1 was processed into a rotor with an outer diameter of 77.3 mm and a thickness of 45 mm.

[0152] Comparative Example 1

[0153] Use commercially available nylon / ferrite rotors off the shelf.

[0154] Evaluation Example 1-Magnetic Property Evaluation

[0155] The magnetic properties (magnetic surface curve) of the rotor prepared in Example 1 and the nylon / ferrite rotor of Comparative Example 1 are measured as follows: using the UHS-2DSM model instrument of Shanghai Pingye Magnetics Co., Ltd., test conditions: normal temperature and pressure, process parameters: 2D measurement mode, test time: 10 seconds, mileage selection: 300.00mT.

[0156] The test results are shown in Table 1 and Figure 1 .

[0157] Table 1: Residual flux density

[0158]

[0159]

[0160] from Figure 1 As can be seen from Table 1, compared with the commercially available nylon / ferrite rotor, the residual magnetic flux density of the rotor prepared using the polyurethane / ferrite composition of Example 1 increases from 217.95 mT to 222.59 mT, an increase of 2.13%.

[0161] Increasing the residual magnetic flux density of the motor rotor increases the motor speed, increases the work done, and improves the efficiency at the same input current. In other words, the rotor prepared in Example 1 can ultimately lead to better efficiency than the commercially available nylon / ferrite rotor.

[0162] Evaluation Example 2 - Mechanical Properties (Durability) Evaluation

[0163] The mechanical properties (durability) of the rotors of Example 1 and Comparative Example 1 were tested as follows: each rotor was mounted on a motor, and then the motor was continuously operated at an output power of 600 W, a load torque of 0.716 Nm, and a speed of 8000 rpm to observe whether a failure would occur and, in the event of a failure, the time from the start of the test to the occurrence of the failure and the failure state.

[0164] The specific results are shown in Table 2 below.

[0165] Table 2: Durability results

[0166] Example No. Time until the fault was observed and the fault status Example 1 Continuous operation for 300 minutes without any failure Comparative Example 1 163 minutes The motor got stuck and the rotor cracked

[0167] The results show that compared with the rotor prepared in Comparative Example 1, the rotor prepared in the embodiment of the present invention did not crack during longer-term use, which indicates that the rotor prepared using the polyurethane-ferrite composition of the present invention has higher mechanical properties and is more resistant to high temperatures; while the rotor prepared in the comparative example cracked during use, which indicates that the rotor prepared using the nylon / ferrite material of the prior art has low hardness and strength, is not resistant to high temperatures, and therefore cannot be used to prepare large rotors.

[0168] The above is only an exemplary embodiment of the present invention. It should be noted that, for those skilled in the art, without departing from the inventive concept of the present invention, improvements can be made to the present invention, but these all belong to the protection scope of the present invention.

Claims

1. A polyurethane-ferrite composition comprising or consisting of: (1) 3-15% by mass, for example 6-10% by mass, of a thermosetting polyurethane prepolymer mixture, wherein the thermosetting polyurethane prepolymer mixture is a combination of: a first isocyanate-terminated polyurethane prepolymer having a number average molecular weight of 10,000-60,000, such as 35,000-45,000, such as 38,000-44,000; and A second hydroxyl-terminated polyurethane prepolymer having a number average molecular weight of 10,000-60,000, such as 35,000-45,000, such as 38,000-44,000; (2) 80-96% by mass, for example 85-92% by mass, of permanent ferrite particles uniformly dispersed in the thermosetting polyurethane prepolymer mixture and optionally surface-treated with a coupling agent; (3) 1-5% by weight, for example 2-3% by weight, of an auxiliary agent uniformly dispersed in the thermosetting polyurethane prepolymer mixture, preferably, the auxiliary agent is a plasticizer and / or a lubricant, Relative to the total mass of the thermosetting polyurethane prepolymer mixture, the permanent magnetic ferrite particles, and the auxiliary agent, the total mass does not include the mass of the coupling agent.

2. The polyurethane-ferrite composition of claim 1, wherein the amount of the first polyurethane prepolymer is 15-85% by mass, such as 25-75% by mass, such as 35-65% by mass, such as 45-55% by mass, such as 48-50% by mass, relative to the total mass of the thermosetting polyurethane prepolymer mixture.

3. The polyurethane-ferrite composition according to claim 1, wherein The first polyurethane prepolymer is prepared by reacting an aromatic and / or alicyclic, for example, aromatic, first diisocyanate with an aliphatic first polyalkylene glycol; then reacting the reaction product with a mixture of an aliphatic first alkylene glycol chain extender and optionally a first polyol, for example, a triol, as a crosslinking agent, or reacting the reaction product with an aliphatic first alkylene glycol chain extender and then optionally reacting with a first polyol, for example, a triol, as a crosslinking agent; For example, the first polyurethane prepolymer is prepared by reacting an aromatic first diisocyanate with an aliphatic first polyalkylene glycol, and then reacting the reaction product with a mixture of an aliphatic first alkylene glycol chain extender and a first trihydroxy compound as a crosslinking agent; and / or The second polyurethane prepolymer is prepared by reacting an aromatic and / or alicyclic, for example, aromatic and alicyclic, second diisocyanate compound with an aliphatic second polyalkylene glycol, and then reacting the reaction product with an aliphatic second alkylene glycol chain extender and optionally an aliphatic second polyhydroxy compound containing three or more hydroxyl groups, for example, a trihydroxy compound, or reacting the reaction product with an aliphatic second alkylene glycol chain extender and then optionally reacting with a second polyhydroxy compound, for example, a trihydroxy compound, as a crosslinking agent; For example, the second polyurethane prepolymer is prepared by reacting a second aromatic and alicyclic diisocyanate with a second polyalkylene glycol and then reacting the reaction product with a second alkylene glycol chain extender; in: The first diisocyanate compound and the second diisocyanate compound are the same or different, and are preferably each independently one or more of the following: an aromatic diisocyanate, such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, 1,3-bis(1-isocyanato-1-methylethyl)benzene, dimethylbiphenyl diisocyanate, polymethylene polyphenyl isocyanate, TDI dimer, TDI trimer; an alicyclic diisocyanate, such as isophorone diisocyanate, dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, cyclohexane dimethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, norbornane diisocyanate, methylcyclohexyl diisocyanate; Preferably, when the first diisocyanate is a mixture of an aromatic diisocyanate and an alicyclic diisocyanate, the amount of the alicyclic diisocyanate in the first diisocyanate is 0.1-10 moles, such as 0.5-2.0 moles, such as 0.75-1.0 moles, relative to 1 mole of the aromatic diisocyanate as the first diisocyanate; Preferably, when the second diisocyanate is a mixture of an aromatic diisocyanate and an alicyclic diisocyanate, the amount of the alicyclic diisocyanate in the second diisocyanate is 0.1-10 mol, such as 0.5-2.0 mol, such as 0.75-1.0 mol, relative to 1 mol of the aromatic diisocyanate as the second diisocyanate; Preferably, the first diisocyanate is toluene diisocyanate, and the second diisocyanate is toluene diisocyanate, isophorone diisocyanate or a mixture thereof, such as a mixture of toluene diisocyanate and isophorone diisocyanate. Preferably, when the second diisocyanate is a mixture of toluene diisocyanate and isophorone diisocyanate, the amount of isophorone diisocyanate is 0.1-10 moles, such as 0.5-2.0 moles, such as 0.75-1.0 moles, relative to 1 mole of toluene diisocyanate. The first polyalkylene glycol and the second polyalkylene glycol are the same as or different from each other, and are preferably each independently one or more of the following: polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol-propylene glycol copolymer, polyethylene glycol-butylene glycol copolymer, polypropylene glycol-butylene glycol copolymer; Preferably, the number average molecular weight of the first polyalkylene glycol and the second polyalkylene glycol are each independently 200-4000, such as 800-3000, such as 1000-2000; Preferably, the first polyalkylene glycol is 0.20-0.90 mol, such as 0.30-0.60 mol, such as 0.40-0.50 mol, relative to 1 mol of the first diisocyanate compound; Preferably, the second polyalkylene glycol is 0.60-0.95 mol, such as 0.70-0.90, such as 0.85-0.90 mol, relative to 1 mol of the second diisocyanate compound; The first alkylene glycol chain extender and the second alkylene glycol chain extender are the same as or different from each other, and are preferably independently one or more of the following: ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol; propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol; 1,4-butanediol; 1,6-hexanediol, for example, the first alkylene glycol chain extender is ethylene glycol, and / or the second alkylene glycol chain extender is diethylene glycol; Preferably, relative to 1 mol of the first diisocyanate compound, the first alkylene glycol chain extender is 0.005-0.30 mol, such as 0.006-0.10 mol, such as 0.008-0.05 mol, such as 0.010-0.020 mol, such as 0.010-0.015 mol; Preferably, the second alkylene glycol chain extender is 0.10-0.30 mol, such as 0.15-0.25, such as 0.20-0.25 mol, relative to 1 mol of the second diisocyanate compound; Preferably, the first polyurethane prepolymer uses the first polyol and / or the second polyurethane prepolymer uses the second polyol; for example, the first polyurethane prepolymer uses the first polyol or the second polyurethane prepolymer uses the second polyol, for example, the first polyurethane prepolymer uses the first polyol, and the second polyurethane prepolymer does not use the second polyol; Preferably, the first polyol and the second polyol are the same or different from each other, and preferably each independently is one or more of the following: glycerol, trimethylolpropane, triethanolamine, triethylolpropane, pentaerythritol, such as trimethylolpropane; Preferably, when used, the first polyol contains 0.02-0.50 mol of OH, such as 0.10-0.30 mol, such as 0.20-0.25 mol, relative to 1 mol of the first diisocyanate; Preferably, when used, the second polyol contains 0.02-0.50 mol of OH, such as 0.10-0.30 mol, such as 0.20-0.25 mol, relative to 1 mol of the second diisocyanate; Preferably, the total amount of hydroxyl groups contained in the first polyalkylene glycol, the first alkylene glycol chain extender and the optional first polyol is 0.4-0.98 mol, such as 0.45-0.70 mol, such as 0.50-0.60 mol, relative to 1 mol of isocyanate groups contained in the first diisocyanate; and / or Preferably, the total amount of hydroxyl groups contained in the second polyalkylene glycol, the second alkylene glycol chain extender and the optional second polyol is 1.02-1.25 mol, for example 1.05-1.15 mol, relative to 1 mol of the isocyanate group contained in the second diisocyanate.

4. The polyurethane-ferrite composition according to claim 1, wherein the permanent magnetic ferrite is barium ferrite such as BaO.6Fe2O3 or strontium ferrite such as SrO.6Fe2O3 or a mixture thereof.

5. The polyurethane-ferrite composition of claim 1, wherein the permanent magnetic ferrite has an average particle size of 0.1-250 microns, such as 0.5-10 microns, such as 1.0-5.0 microns, such as 1.0-1.5 microns.

6. The polyurethane-ferrite composition according to claim 1, wherein the permanent ferrite is surface treated with a coupling agent, preferably the coupling agent is one or more of the following: a silane coupling agent, such as γ-aminopropyl triethoxysilane, γ-(2,3-epoxypropoxy)propyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane, γ-mercaptopropyl trimethylsilane, vinyl triethoxysilane, vinyl tri(2-methoxyethoxy) silane, N-(β-aminoethyl)-γ-aminopropyl methyl dimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane, diethylaminomethyl triethoxysilane, aniline methyl triethoxysilane, 3-ureapropyl triethyl Oxysilane, bis(3-trimethoxysilylpropyl)amine; titanate coupling agent, such as isopropyl triisostearate titanate, isopropyl dioleyl (dioctyl phosphate) titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl trioleyl titanate, isopropyl tri(dioctyl pyrophosphate) titanate, bis(dioctyl pyrophosphate) ethylene titanate, tetraisopropyl di(dioctyl phosphite) titanate; zirconate coupling agent, such as tetrakis(triethanolamine) zirconate, bis(diethyl citrate) dipropoxy zirconium chelate; preferably, the coupling agent is used in an amount of 0.5-3.0%, such as 1.0-2.0% by mass of the total mass of the thermosetting polyurethane prepolymer mixture.

7. The polyurethane-ferrite composition according to any one of claims 1 to 5, wherein: When present, the plasticizer is selected from one or more of the following: dioctyl terephthalate (DOTP), dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), dioctyl adipate (DOA), dibutyl sebacate (DBS), tricresyl phosphate (TCP), triphenyl phosphate (TPP), diethylene glycol dibenzoate (DEDB); and / or When present, the lubricant is selected from one or more of the following: zinc stearate, calcium stearate, lead stearate, barium stearate, n-butyl stearate, glyceryl monostearate, glyceryl tristearate, pentaerythritol stearate, stearic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide; Preferably, when a plasticizer and a lubricant are present, the mass ratio of the plasticizer to the lubricant is 1:0.1-10, such as 1:0.2-5, such as 1:0.5-2, such as 1:

1.

8. A method for preparing a polyurethane-ferrite composition as claimed in any one of claims 1 to 7, comprising the steps of: Providing permanent magnet ferrite particles, and optionally, surface-treating the permanent magnet ferrite particles with a coupling agent to obtain surface-treated permanent magnet ferrite particles; providing a first component including a first polyurethane prepolymer and optionally a solvent; providing a second component comprising a second polyurethane prepolymer and optionally a solvent; dispersing optionally treated permanent magnetic ferrite particles in one of the first component and the second component to obtain a first mixture; The other of the first component and the second component and an adjuvant are mixed with the first mixture.

9. An injection molding method, comprising injection molding the polyurethane-ferrite composition according to any one of claims 1 to 7 or the polyurethane-ferrite composition prepared by the method according to claim 8 in the presence of a magnetic field that orients the permanent ferrite contained in the composition, preferably during the injection molding process, the strength of the magnetic field is 0.8-4.0 Tesla, the mold temperature of the injection molding machine is 100-120° C., the injection pressure is 1000-1800 bar, and the injection temperature and the injection pressure are maintained for 60-300 seconds before demolding.

10. An article prepared by the injection molding method according to claim 9, preferably, the article is a motor rotor.

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