Magnetic tape with permanent magnetic coating and preparation method thereof

Abstract

The invention discloses a magnetic tape with a persistent magnetic coating and a preparation method of the magnetic tape. The magnetic tape comprises a non-magnetic support body, a non-magnetic layer, the persistent magnetic coating and a back coating, the persistent magnetic coating is obtained by coating persistent magnetic slurry and then curing, and the persistent magnetic slurry comprises the following raw materials in parts by weight: 80-99 parts of nanoscale magnetic particles, 1-20 parts of a binder, 1-5 parts of a dispersant, 1-5 parts of a lubricant, 1-3 parts of a curing agent and 300-500 parts of a solvent. According to the invention, the combination of polyethyleneimine and a long-chain isocyanate lubricant is added into the formula of the magnetic layer, the introduced long-chain isocyanate can increase the durability of the magnetic tape, and meanwhile, amino and isocyanate are subjected to an addition reaction to fix long-chain alkane on the surface of the magnetic layer, so that the consumption of the lubricant in the running process of the magnetic tape is further reduced, and the service life of the magnetic tape is prolonged. The lubricant composition formula effectively improves the durability of the storage tape.

Description

Technical Field

[0001] The invention relates to the field of magnetic recording materials, in particular to a magnetic tape with a permanent magnetic coating and a preparation method thereof. Background Art

[0002] With the rapid development of emerging technologies such as big data, cloud computing, and artificial intelligence (AI), the demand for data storage is growing exponentially and has entered the ZB (ZB) era. Among various data storage technologies, magnetic recording technology has long occupied an important position in the field of data storage due to its high reliability, large capacity, and low cost. Common magnetic recording media include hard disk drives (HDDs) and tape storage media. Among them, tape storage has relatively low cost and relatively large storage capacity. At the same time, tape storage media can reduce carbon emissions by 95%, which is more in line with the requirements of sustainable development. Therefore, tape storage is still widely used in fields such as data backup and long-term data storage, and has become the main way to back up and archive large amounts of data.

[0003] Magnetic storage technology not only has requirements in terms of capacity, but also must be optimized in multiple dimensions such as data access speed, durability and cost-effectiveness. In the existing technology, the friction between the tape and the head is highly correlated with durability. If the friction between the tape and the head cannot be effectively controlled, the friction and thermal effects will cause the tape performance to decay rapidly. More seriously, it will cause severe wear of the head or signal loss, which will cause the entire storage device to fail.

[0004] Based on the above reasons, it is particularly important to reduce the friction coefficient between the tape and the head during the long-term operation of the tape, thereby improving the durability of the tape.

[0005] In the prior art, it is often necessary to add a small amount of long-chain alkane compounds to the magnetic layer and / or non-magnetic layer to achieve the lubrication function, such as Japanese patents JP2016126817A5 and JP6325977B2. Common long-chain alkane lubricants are mainly composed of one or more of the following three categories: The first category is fatty acids, such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, erucic acid, and elaidic acid. The second category is fatty acid esters, such as esters of dodecanoic acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, erucic acid, and elaidic acid. The third category is fatty acid amides, such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, and the like. Another major category of compounds is fluorinated polymers, such as patent CN115691567A. By adding fluorine-containing compounds to the magnetic material, the water contact angle measured on the surface of the magnetic layer during the sliding of the magnetic head is controlled to be greater than 0.85 relative to the water contact angle on the surface of the magnetic layer before sliding with the magnetic head. This can significantly improve the signal-to-noise ratio (SNR) stability of the magnetic tape.

[0006] Although the above-mentioned long-chain alkane compounds or fluorine-containing compounds play an important role in reducing the friction coefficient between the magnetic medium and the magnetic head, since the above-mentioned lubricants are physically blended and added to the magnetic layer and / or non-magnetic layer, the force between the lubricant and the resin is physically connected. As the magnetic head and the magnetic medium continue to interact, the friction coefficient will increase rapidly after the lubricant is exhausted, which is not conducive to the durability of the magnetic recording device.

[0007] Therefore, it is necessary to improve the existing technology to provide a more reliable solution. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a magnetic tape with a permanent magnetic coating and a preparation method thereof in view of the deficiencies in the above-mentioned prior art.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: In a first aspect of the present invention, a magnetic tape with a permanent magnetic coating is provided, comprising a non-magnetic support, a non-magnetic layer arranged on the surface of the non-magnetic support, a permanent magnetic coating arranged on the surface of the non-magnetic layer, and a back coating arranged on the back of the non-magnetic support;

[0010] The permanent magnetic coating is obtained by coating a permanent magnetic slurry and then curing the coating. The permanent magnetic slurry includes the following raw materials in parts by weight:

[0011] 80-99 parts of nano-scale magnetic particles, 1-20 parts of binder, 1-5 parts of dispersant, 1-5 parts of lubricant, 1-3 parts of curing agent, and 300-500 parts of solvent.

[0012] Preferably, the nano-scale magnetic particles are selected from at least one of hexagonal barium ferrite and hexagonal strontium ferrite, and the average particle size is not greater than 50 nm.

[0013] Preferably, the binder is selected from at least one of polyurethane resin, polyester resin, polyamide resin, vinyl chloride resin, styrene resin, acrylonitrile resin, acrylic resin, cellulose resin, epoxy resin, phenoxy resin, polyvinyl acetal, polyvinyl butyral resin, and polyvinyl alkyl aldehyde resin.

[0014] Preferably, the dispersant is at least one selected from aromatic hydrocarbon compounds having phenolic hydroxyl groups, wherein the aromatic ring contained therein is a monocyclic or polycyclic structure or a condensed ring.

[0015] Preferably, the lubricant is a composition of an active amine and a long-chain isocyanate, and the weight ratio of the active amine to the long-chain isocyanate is 1:1 to 1:20.

[0016] Preferably, the active amine is at least one of polyethyleneimine and polyvinylamine.

[0017] Preferably, the long-chain alkane isocyanate is one or more of dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate, eicosyl isocyanate, and docosyl isocyanate, preferably at least one of octadecyl isocyanate.

[0018] Preferably, the curing agent is polyisocyanate.

[0019] A second aspect of the present invention provides a method for preparing a magnetic tape having a permanent magnetic coating as described above, comprising the following steps:

[0020] S1. Mixing nano-scale magnetic particles, a binder, a dispersant, a lubricant, a curing agent and a solvent evenly using a sand mill to obtain a persistent magnetic slurry;

[0021] S2, mixing the non-magnetic inorganic powder, carbon black and solvent evenly using a sand mill to obtain a non-magnetic slurry;

[0022] S3, mixing carbon black, a binder, a curing agent, and a solvent evenly using a sand mill to obtain a back coating slurry;

[0023] S4, evenly coating the non-magnetic slurry on the surface of the non-magnetic support, and drying to form a non-magnetic layer;

[0024] S5, applying a magnetic field, uniformly coating the surface of the non-magnetic layer with a persistent magnetic slurry, then applying a magnetic field for magnetic orientation treatment, uniformly coating the back coating slurry on the back of the non-magnetic support, and then drying to form a persistent magnetic coating and a back coating respectively;

[0025] S6. Polishing, wiping and surface smoothing the magnetic layer to obtain a magnetic tape with a durable magnetic coating.

[0026] Preferably, the non-magnetic inorganic powder is α-iron oxide;

[0027] The solvent is selected from at least one of acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, propanol, methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate, ethylene glycol acetate, diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, dioxane, benzene, toluene, xylene, dichloromethane, dichloroethane, carbon tetrachloride, chloroform, and chlorobenzene.

[0028] The beneficial effects of the present invention are:

[0029] The present invention provides a magnetic tape with a durable magnetic coating and a preparation method thereof. The present invention can greatly improve the wear resistance of the magnetic tape and thus improve its service life by optimizing the lubricant in the magnetic coating. Specifically, the present invention adds a combination of polyethyleneimine and a long-chain isocyanate lubricant to the magnetic layer formula. The introduced long-chain isocyanate can increase the durability of the magnetic tape (long-chain alkanes have low surface energy and a small friction coefficient, so the durability of the magnetic tape can be increased). At the same time, amino groups and isocyanates fix the long-chain alkanes on the surface of the magnetic layer through an addition reaction, further reducing the consumption of lubricants during the operation of the magnetic tape. The lubricant combination formula effectively improves the durability of the stored magnetic tape.

[0030] The method of the present invention has a simple process and high repeatability, and solves the industry problem of the difficulty in further improving the performance of traditional lubricants; the lubricant system of the present invention can match the magnetic layer formula of existing magnetic tapes and meet the high standard requirements of storage magnetic tapes for lubrication performance. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0032] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0033] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0034] The present invention provides a magnetic tape with a permanent magnetic coating, comprising a non-magnetic support, a non-magnetic layer arranged on the surface of the non-magnetic support, a permanent magnetic coating arranged on the surface of the non-magnetic layer, and a back coating arranged on the back of the non-magnetic support;

[0035] The permanent magnetic coating is obtained by coating a permanent magnetic slurry and then curing it. The permanent magnetic slurry includes the following raw materials in parts by weight:

[0036] 80-99 parts of nano-scale magnetic particles, 1-20 parts of binder, 1-5 parts of dispersant, 1-5 parts of lubricant, 1-3 parts of curing agent, and 300-500 parts of solvent.

[0037] In a preferred embodiment, the nanoscale magnetic particles are selected from at least one of hexagonal barium ferrite and hexagonal strontium ferrite. From the viewpoint of improving the recording density, a strong magnetic powder with a small average particle size is preferred, for example, the average particle size is not greater than 50 nm, more preferably less than 45 nm, further preferably less than 40 nm, further preferably less than 35 nm, further preferably less than 30 nm, further preferably less than 25 nm, and further preferably less than 20 nm.

[0038] In a preferred embodiment, the binder is selected from at least one of polyurethane resin, polyester resin, polyamide resin, vinyl chloride resin, styrene resin, acrylonitrile resin, acrylic resin, cellulose resin, epoxy resin, phenoxy resin, polyvinyl acetal, polyvinyl butyral resin, and polyvinyl alkyl aldehyde resin. These resins can be homopolymers or copolymers. These resins can also be used as binders in the non-magnetic layer and / or the back coating. The average molecular weight of the resin used as the binder is a weight average molecular weight, for example, it can be more than 10,000 and less than 200,000.

[0039] As a dispersant, it is used to improve the dispersibility of the oxide abrasive. Compounds that can be used as such dispersants include, for example, aromatic hydrocarbon compounds having phenolic hydroxyl groups. The aromatic ring contained in the above aromatic hydrocarbon compound may be a single ring, a polycyclic structure, or a condensed ring. In order to improve the dispersibility of the oxide abrasive, aromatic hydrocarbon compounds containing benzene rings and / or naphthalene rings are preferred. In addition, the above aromatic hydrocarbon compound may have a substituent other than the phenolic hydroxyl group. As substituents other than the phenolic hydroxyl group, for example, halogen atoms, alkyl groups, alkoxy groups, amino groups, acyl groups, nitro groups, nitroso groups, hydroxyalkyl groups, etc. are mentioned, and halogen atoms, alkyl groups, alkoxy groups, amino groups, and hydroxyalkyl groups are preferred.

[0040] In a preferred embodiment, the lubricant is a composition of an active amine and a long-chain isocyanate, and the weight ratio of the active amine to the long-chain isocyanate is 1:1 to 1:20.

[0041] In a preferred embodiment, the active amine is at least one of polyethyleneimine and polyvinylamine, and has a molecular weight between 3000-50000.

[0042] In a preferred embodiment, the long-chain alkane isocyanate is one or more of dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate, eicosyl isocyanate, and docosyl isocyanate, preferably at least one of octadecyl isocyanate.

[0043] In a preferred embodiment, the curing agent is polyisocyanate.

[0044] In a preferred embodiment, the persistent magnetic slurry may further include additives such as mildew preventers, antistatic agents, antioxidants, and the like.

[0045] The present invention also provides a method for preparing the magnetic tape having a permanent magnetic coating as described above, comprising the following steps:

[0046] S1. Mixing nano-scale magnetic particles, a binder, a dispersant, a lubricant, a curing agent and a solvent evenly using a sand mill to obtain a persistent magnetic slurry;

[0047] S2, mixing the non-magnetic inorganic powder, carbon black and solvent evenly using a sand mill to obtain a non-magnetic slurry;

[0048] S3, mixing carbon black, a binder, a curing agent, and a solvent evenly using a sand mill to obtain a back coating slurry;

[0049] S4, evenly coating the non-magnetic slurry on the surface of the non-magnetic support, and drying to form a non-magnetic layer;

[0050] S5, applying a magnetic field, uniformly coating the surface of the non-magnetic layer with a persistent magnetic slurry, then applying a magnetic field for magnetic orientation treatment, uniformly coating the back coating slurry on the back of the non-magnetic support, and then drying to form a persistent magnetic coating and a back coating respectively;

[0051] S6. Polishing, wiping and surface smoothing the magnetic layer to obtain a magnetic tape with a durable magnetic coating.

[0052] In a preferred embodiment, the non-magnetic inorganic powder is α-iron oxide.

[0053] In a preferred embodiment, the solvent is selected from at least one of acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, propanol, methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate, ethylene glycol acetate, diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, dioxane, benzene, toluene, xylene, dichloromethane, dichloroethane, carbon tetrachloride, chloroform, and chlorobenzene.

[0054] The present invention adds a small amount of polyethyleneimine and long-chain isocyanate as lubricants into the magnetic coating, and fixes the long-chain alkane compound with lubricating effect on the surface of the magnetic layer through chemical bonds through the nucleophilic addition reaction of the amino group and the NCO group, thereby preventing the friction coefficient caused by the long-term mutual use of the magnetic medium and the magnetic head, and reducing the attenuation or loss of the magnetic performance of the magnetic tape.

[0055] The above is the overall concept of the present invention, and detailed embodiments and comparative examples are provided below on the basis of the overall concept of the present invention to further illustrate the present invention.

[0056] Example 1

[0057] A magnetic tape with a permanent magnetic coating comprises a non-magnetic support, a non-magnetic layer arranged on the surface of the non-magnetic support, a permanent magnetic coating arranged on the surface of the non-magnetic layer and a back coating arranged on the back of the non-magnetic support.

[0058] (1) The permanent magnetic coating is obtained by coating a permanent magnetic slurry and then curing the coating. The permanent magnetic slurry includes the following raw materials in parts by weight:

[0059] Nano-scale magnetic particles: 100.0 parts of hexagonal barium ferrite powder with an average particle size of 21 nm;

[0060] Binder: 10 parts of vinyl chloride resin MR-110, 20 parts of polyester polyurethane resin UR-8200;

[0061] Dispersant: DISPERBYK-180 5 parts;

[0062] Curing agent: 2.5 parts of polyisocyanate L75;

[0063] Lubricant: 2 parts of PEI, 3 parts of octadecyl isocyanate;

[0064] Solvent: 200.0 parts of cyclohexanone and 200.0 parts of methyl ethyl ketone.

[0065] (2) The non-magnetic slurry includes the following raw materials in parts by weight:

[0066] Non-magnetic inorganic powder: 100.0 parts of α-iron oxide, average particle size (average major axis length): 0.15 μm, average needle ratio: 7;

[0067] 20.0 parts of carbon black, average particle size: 20 nm.

[0068] Solvent: 140 parts of cyclohexanone, 800 parts of methyl ethyl ketone.

[0069] (3) The back coating slurry includes the following raw materials in parts by weight:

[0070] 5 parts of carbon black, 5 parts of binder (vinyl chloride resin MR-110), 0.26 parts of curing agent (polyisocyanate L75);

[0071] Solvent: 35 parts of cyclohexanone and 42.5 parts of methyl ethyl ketone.

[0072] The method for preparing the magnetic tape having a permanent magnetic coating comprises the following steps:

[0073] S1. According to the above ratio, the nano-scale magnetic particles, binder, dispersant, lubricant, curing agent and solvent are sanded for 24 hours using a sand mill, and the sand mill uses zirconium dioxide beads with a bead diameter of 0.5 mm;

[0074] The sand-milled product was added to a mixer, stirred for 2 hours, and then subjected to ultrasonic dispersion treatment using a flow ultrasonic disperser, and then filtered to obtain a persistent magnetic slurry;

[0075] S2, mixing the non-magnetic inorganic powder, carbon black and solvent using the same method as step S1 to obtain a non-magnetic slurry;

[0076] S3, mixing the non-magnetic inorganic powder and the solvent using the same method as step S1 to obtain a back coating slurry;

[0077] S4, evenly coating the non-magnetic slurry on the surface of the non-magnetic support (5.00 μm PET), drying, and forming a non-magnetic layer with a thickness of 250 nm;

[0078] S5. Under the applied magnetic field (magnetic field strength: 0.15T), a persistent magnetic slurry is uniformly coated on the surface of the non-magnetic layer. A magnetic field is applied to the slurry while it is in a wet state to perform a magnetic orientation treatment (a DC magnetic field with a magnetic field strength of 0.30T is vertically applied to the surface of the coating layer to perform a vertical orientation treatment). The back coating slurry is uniformly coated on the back side of the non-magnetic support, and then dried to form a persistent magnetic coating with a thickness of 50nm and a back coating with a thickness of 0.50μm, respectively.

[0079] S6. Polish and wipe the magnetic layer, and then smooth the surface: use a metal roller calendering roller to calender at a speed of 80m / min, a linear pressure of 300kg / cm, and a calendering temperature of 100°C to finally obtain a magnetic tape with a durable magnetic coating.

[0080] Example 2

[0081] This example is basically the same as Example 1, except that the lubricant in the persistent magnetic slurry of this example is changed to: 2 parts of PEI and 3 parts of hexadecyl isocyanate.

[0082] Example 3

[0083] This example is basically the same as Example 1, except that the lubricant in the durable magnetic slurry of this example is changed to: 2 parts of PEI and 3 parts of n-octyl isocyanate.

[0084] Example 4

[0085] This example is basically the same as Example 1, except that the lubricant in the persistent magnetic slurry of this example is changed to: 1 part of PEI and 2 parts of octadecyl isocyanate.

[0086] Example 5

[0087] This example is basically the same as Example 1, except that the lubricant in the persistent magnetic slurry of this example is changed to: 1 part of PEI and 2 parts of hexadecyl isocyanate.

[0088] Example 6

[0089] This example is basically the same as Example 1, except that the lubricant in the durable magnetic slurry of this example is changed to: 1 part of lubricant PEI and 2 parts of n-octyl isocyanate.

[0090] Comparative Example 1

[0091] This example is basically the same as Example 1, except that the lubricant in the persistent magnetic slurry of this example is changed to: 2 parts of stearic acid, 2 parts of butyl stearate, and 0.2 parts of stearic acid amide.

[0092] Comparative Example 2

[0093] This example is basically the same as Example 1, except that the lubricant in the persistent magnetic slurry of this example is changed to 5 parts of PEI.

[0094] Comparative Example 3

[0095] This example is basically the same as Example 1, except that the lubricant in the durable magnetic slurry of this example is changed to 5 parts of octadecyl isocyanate.

[0096] The magnetic tapes prepared in Examples 1-6 and Comparative Example 1 were subjected to life tests:

[0097] Testing was performed using an IITRI loop tester with a tape length of 54 inches, a tape tension of 8 ounces, a wrap angle of 15 degrees, and an aluminum head coated with 5 mils of chrome. The tape speed was 32 ips. The minimum number of runs at which debris or oxide layer appeared was recorded.

[0098] The test results are shown in Table 1 below:

[0099] Table 1

[0100]

[0101] According to the test results in Table 1, Comparative Example 1 used a conventional lubricant formula, and the magnetic tape prepared therefrom showed obvious removal of the oxide layer and accumulated debris after 50,000 passes. Comparative Example 2 only added polyethyleneimine, so it did not play an effective lubricating role, and debris should have appeared after running 15,000 times. Comparative Example 3 added octadecyl isocyanate, which had a certain lubricating function, but was still slightly worse than Example 1, and debris appeared after running 40,000 times. On the other hand, the magnetic tapes of Examples 1, 2, 4, and 5 of the present invention did not show any debris or visible removal of the oxide layer after cumulatively passing more than 100,000 times, and looked almost brand new. Since the magnetic tapes of Examples 3 and 6 used long-chain alkanes with eight carbon atoms, the lubrication effect was poor, and debris appeared after less than 30,000 passes.

[0102] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A magnetic tape having a permanent magnetic coating, characterized in that The invention comprises a non-magnetic support, a non-magnetic layer disposed on the surface of the non-magnetic support, a permanent magnetic coating disposed on the surface of the non-magnetic layer, and a back coating disposed on the back of the non-magnetic support; The permanent magnetic coating is obtained by coating a permanent magnetic slurry and then curing the coating. The permanent magnetic slurry includes the following raw materials in parts by weight: 80-99 parts of nano-scale magnetic particles, 1-20 parts of binder, 1-5 parts of dispersant, 1-5 parts of lubricant, 1-3 parts of curing agent, and 300-500 parts of solvent.

2. The magnetic tape with a permanent magnetic coating according to claim 1, characterized in that The nano-scale magnetic particles are selected from at least one of hexagonal barium ferrite and hexagonal strontium ferrite, and the average particle size is not greater than 50 nm.

3. The magnetic tape with a permanent magnetic coating according to claim 1, characterized in that The binder is selected from at least one of polyurethane resin, polyester resin, polyamide resin, vinyl chloride resin, styrene resin, acrylonitrile resin, acrylic resin, cellulose resin, epoxy resin, phenoxy resin, polyvinyl acetal, polyvinyl butyral resin, and polyvinyl alkyl aldehyde resin.

4. The magnetic tape with a permanent magnetic coating according to claim 1, characterized in that The dispersant is at least one selected from aromatic hydrocarbon compounds having phenolic hydroxyl groups, wherein the aromatic ring contained therein is a monocyclic or polycyclic structure or a condensed ring.

5. The magnetic tape with a permanent magnetic coating according to claim 1, characterized in that The lubricant is a composition of active amine and long-chain isocyanate, and the weight ratio of the active amine to the long-chain isocyanate is 1:1 to 1:

20.

6. The magnetic tape with a permanent magnetic coating according to claim 5, characterized in that The active amine is at least one of polyethyleneimine and polyvinylamine.

7. The magnetic tape with a permanent magnetic coating according to claim 5, characterized in that The long-chain alkane isocyanate is one or more of dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate, eicosyl isocyanate, and docosyl isocyanate, preferably at least one of octadecyl isocyanate.

8. The magnetic tape having a permanent magnetic coating according to claim 1, characterized in that The curing agent is polyisocyanate.

9. A method for preparing a magnetic tape having a permanent magnetic coating as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Mixing nano-scale magnetic particles, a binder, a dispersant, a lubricant, a curing agent and a solvent evenly using a sand mill to obtain a persistent magnetic slurry; S2, mixing the non-magnetic inorganic powder, carbon black and solvent evenly using a sand mill to obtain a non-magnetic slurry; S3, mixing carbon black, a binder, a curing agent, and a solvent evenly using a sand mill to obtain a back coating slurry; S4, evenly coating the non-magnetic slurry on the surface of the non-magnetic support, and drying to form a non-magnetic layer; S5, applying a magnetic field, uniformly coating the surface of the non-magnetic layer with a persistent magnetic slurry, then applying a magnetic field for magnetic orientation treatment, uniformly coating the back coating slurry on the back of the non-magnetic support, and then drying to form a persistent magnetic coating and a back coating respectively; S6. Polishing, wiping and surface smoothing the magnetic layer to obtain a magnetic tape with a durable magnetic coating.

10. The method for preparing a magnetic tape having a permanent magnetic coating according to claim 1, characterized in that: The non-magnetic inorganic powder is α-iron oxide; The solvent is selected from at least one of acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, propanol, methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate, ethylene glycol acetate, diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, dioxane, benzene, toluene, xylene, dichloromethane, dichloroethane, carbon tetrachloride, chloroform, and chlorobenzene.

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