JPH04330635A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the high-performance magnetic recording medium by improving the adhesiveness between a magnetic layer and a base. CONSTITUTION:This process for producing the magnetic recording medium provided with the magnetic layer contg. magnetic powder and fatty acid on the base consists in providing a stage for kneading a compsn. for a magnetic coating material contg. the magnetic powder consisting of cobalt-contg. iron oxide expressed by FeOx (where (x)is 1.34 to 1.48) and the above-mentioned fatty acid of 2.5 to 6.0 pts.wt. per 100 pts.wt. magnetic powder without subjecting the base to a pretreatment for improving the adhesiveness and specifying the dry film thickness of the magnetic layer to be applied and provided on the base to 0.5 to 2.8mu.

Description

Description: FIELD OF INDUSTRIAL APPLICATION The present invention relates to a method for manufacturing magnetic recording media such as magnetic disks, magnetic tapes, and magnetic sheets. [0002] Conventionally, as a means of increasing the adhesion of a magnetic layer to a support, one or both sides of the support are treated with corona discharge, or urethane polymer, A thin subbing layer (hereinafter referred to as easy adhesion) is provided by attaching a film of acrylic polymer or polyester or the like and simultaneously stretching the film, and then a magnetic layer is applied. However, when the corona discharge treatment is performed, the surface of the support is charged and therefore attracts dust from the surrounding area. The attracted dust prevents smooth contact between the magnetic recording medium and the magnetic head, causing dropout. In addition, for example, in the case of polyethylene terephthalate film, which is often used as a support, corona discharge decomposes ester bonds and generates carboxyl groups and hydroxyl groups, making the surface brittle. However, there were some drawbacks such as the generation of dust due to friction. [0005] Furthermore, when the adhesion treatment is performed, the surface of the adhesion film is roughened to improve adhesion, and the thinner the magnetic layer is, the lower the smoothness of the magnetic layer surface becomes. . This results in poor contact with the running magnetic head, resulting in spacing loss and deterioration of electromagnetic conversion characteristics. [0006] Furthermore, an increase in cost due to the addition of an easy adhesion process has also been a problem. In addition, there were other problems such as show-through (transferring to the adjacent film that comes into contact with the film) when the easily-adhesive treated film is wound onto a roll, and scratches on the easily-adhesive surface during transportation. By the way, it is well known that fatty acids such as stearic acid are used as a lubricant for the magnetic layer of a magnetic recording medium. Fatty acids also act as dispersants for magnetic powder when preparing magnetic paints for forming magnetic layers, and also act as dispersants for magnetic powder.
After the magnetic recording medium is formed, it is a very useful additive for controlling the slipperiness of the surface of the magnetic layer and improving running stability or still image durability. However, if too much fatty acid is added in order to improve the above-mentioned performance, it will ooze out from the surface of the magnetic layer and stain the magnetic head, causing a decrease in output. Furthermore, it has been said that increasing the amount of fatty acid added causes a relative decrease in the magnetic powder concentration, resulting in a decrease in electromagnetic conversion characteristics. [0009] Furthermore, in general, when the thickness of the magnetic layer is reduced, the amount of adhesive is substantially reduced, and the adhesion with the support tends to deteriorate, and in the case of magnetized magnetic powder, dispersion is difficult. The coating film also became brittle, and the adhesiveness decreased significantly. OBJECT OF THE INVENTION The object of the present invention is to provide a thin film magnetic recording medium using magnetized magnetic powder, which has improved physical properties by improving the adhesion between the magnetic layer and the support. The purpose is to provide a manufacturing method. Structure of the Invention and Its Effects The present invention provides a method for manufacturing a magnetic recording medium in which a magnetic layer containing magnetic powder and a fatty acid is provided on a support, in which the support is provided with a magnetic layer containing magnetic powder and a fatty acid. FeOx (however, x is 1.34 to 1) without pretreatment
．． It is 48. ) Magnetic powder made of cobalt-containing iron oxide and 2.5 to 100 parts by weight of the magnetic powder
A step of kneading a magnetic coating composition containing 6.0 parts by weight of the fatty acid is provided, and the dry film thickness of the magnetic layer coated on the support is 0.5 to 2.8 μm. The present invention relates to a method of manufacturing a magnetic recording medium, characterized in that: According to the method of the present invention, the relatively thin film magnetic recording medium produced is not subjected to corona discharge or adhesion treatment for improving magnetic layer adhesion, and therefore, various problems caused by these treatments are avoided. defects can be prevented. In addition, despite the relatively high fatty acid content, there is no blooming (a phenomenon in which additives such as fatty acids ooze out onto the surface of the magnetic layer, which causes contamination of the magnetic head), and the adhesion is good. Therefore, various physical properties of the manufactured magnetic recording medium are also improved. The magnetic powder used in the present invention is so-called magnetized iron oxide represented by FeOx. This magnetic powder is manufactured, for example, by the following method. That is,
First, ferrous hydroxide is precipitated from an aqueous ferrous sulfate solution and an aqueous caustic soda solution using a known method. When preparing cobalt-containing FeOx, it is preferable to add a water-soluble salt such as cobalt chloride to the above-mentioned ferrous sulfate aqueous solution. [0016] Furthermore, it is also possible to prepare modified iron oxide by introducing atoms such as Al, Si, and P in addition to cobalt. Next, the precipitate is stirred while blowing air into it to form goethite (α-FeOOH). After washing and drying this, dehydration and reduction are further performed in a firing furnace. At this time, by adjusting the firing temperature and firing time appropriately,
Magnetitized magnetic powder having a desired x value can be obtained. Furthermore, if the above treatment with cobalt is not performed, the magnetized magnetic powder obtained at this stage is dispersed in an aqueous solution containing cobalt chloride, cobalt sulfate, etc., and neutralized with a caustic soda aqueous solution. do. After stirring and raising the temperature, the slurry of iron oxide is taken out, washed with water, filtered, and dried to obtain Co-containing iron oxide. In this case as well, modified iron oxide can be prepared by introducing atoms such as Al, Si, and P in addition to Co. Magnetitized FeOx used in the present invention
Although x in the range of 1.34 to 1.48 can be used, preferably x is in the range of 135 to 1.42. If x is less than 1.34, the erasing rate characteristics and transfer characteristics of the tape will deteriorate, the stability over time will be poor, and the electromagnetic conversion characteristics will deteriorate. Moreover, when x exceeds 1.48, the density of the tape becomes low and the light transmittance becomes high, resulting in a non-standard product. [0020] The binder used in the method of the present invention includes:
Examples include those described in JP-A-3-62311, page 3, lower right column, line 10 to page 4, upper left column, line 15. [0021] These resins have polar groups in their molecules that
Compatibility with the magnetic powder is improved, which further improves the dispersibility of the magnetic powder and prevents agglomeration of the magnetic powder, further improving the stability of the coating liquid, which in turn improves the durability of the medium. can be done. Such a binder, especially a vinyl chloride copolymer, can be prepared by copolymerizing a vinyl chloride monomer, a copolymerizable monomer containing an alkali salt of sulfonic acid or phosphoric acid, and other copolymerizable monomers as necessary. Obtainable. Since this copolymer is based on vinyl synthesis, it is easy to synthesize, and various copolymer components can be selected, so that the properties of the copolymer can be optimally adjusted. The fatty acids used in the method of the present invention are known as dispersants or lubricants, and include caproic acid, myristic acid, oleic acid, palmitic acid, stearic acid,
Other examples include those of JP-A-3-8113, page 6, lines 14 to 16 of the lower left column to the lower right column. One or more of these fatty acids may be used in an amount of 2.5 to 6.0 parts by weight, preferably 3.0 to 6.0 parts by weight, per 100 parts by weight of the magnetic powder. Can be done. If the amount of fatty acid is less than 2.5 parts by weight, the adhesion between the magnetic layer and the support is insufficient, and the magnetic layer is likely to peel off or drop out. If it exceeds 6.0 parts by weight, a large amount of fatty acid will precipitate from the surface of the magnetic layer, causing a blooming phenomenon and staining the head, making it impossible to achieve the object of the present invention. [0025] In forming the above-mentioned magnetic layer, other additives such as a dispersant and lubricant other than the above-mentioned fatty acids, an abrasive, an antistatic agent, and a filler may be contained as necessary. [0026] As a dispersant, JP-A-3-16015
Examples include those described in the upper right column, lines 12 to 20 of page 6 of the publication. These dispersants have a ratio of 0.5 to 5 for magnetic powder.
It is preferable to add it within a range of % by weight. Examples of the lubricant include those described in JP-A-3-8113, page 6, lower right column, line 18 to page 7, upper right column, line 13. [0028] Non-magnetic abrasive particles may also be added, including alumina (α-Al2O3, β-Al2
O3, γ-Al2O3, δ-Al2O3,
ζ-Al2O3, η-Al2O3, θ-Al2
O3, κ-Al2 O3, χ-Al2 O3,
ρ-Al2O3, etc.), alumina hydrate, alumina silicate, other silicates, silicon carbide, boron carbide, other carbides, etc., non-magnetic oxides such as chromium oxide, iron oxide, boron nitride, titanium oxide, Silicon oxide, silicon nitride, zirconium oxide, zinc oxide, cerium oxide, magnesium oxide, etc. are used. The content of this abrasive is magnetic powder 10
It is preferably 20 parts by weight or less with respect to 0 parts by weight, and the average particle diameter is preferably 0.05 to 6 μm. [0029] As an antistatic agent, JP-A-3-1601
5, page 6, lower left column, line 18 to page 6, lower right column, line 11. The above antistatic agent is 0.0% relative to the binder.
It is preferably added in an amount of 0.01 to 40% by weight. [0030] Also, as light-shielding carbon black,
For example, JP-A-3-16015, page 5, upper right column, line 1~
The degree of light shielding can be increased by using the material shown in row 5 of the upper right column on page 5. [0031] In order to improve the durability of the constituent layers such as the magnetic layer of the magnetic recording medium of the present invention, various hardening agents can be contained, for example, isocyanate can be contained. Examples of aromatic isocyanates that can be used include, for example, JP-A-3-49032, page 3, upper right column 14.
The one described in line 7 of the lower left column on page 3 is preferable. [0033] Examples of solvents to be added to the paint forming the magnetic layer include those described in JP-A-3-16015, page 6, lower right column, line 12 to page 7, upper left column, line 5. [0034] The support according to the present invention is disclosed in Japanese Patent Application Laid-Open No.
49032, page 4, upper right column, line 5 to page 4, upper right column, line 12. [0035] The thickness of these supports is about 3 to 100 μm in the case of a film or sheet, preferably 5 to 5 μm.
0 μm, and 30 μm for disks and cards.
The diameter is about 10 mm, and when it is drum-shaped, it is used in a cylindrical shape, and its shape is determined depending on the recorder used. Next, kneading is carried out in the following manner. That is, magnetic powder, binder (polyurethane resin and other resins as necessary), and other additives are adjusted to a solid content concentration of 70 to 90% by weight using a solvent. This composition is mixed with a kneader at a temperature of 20 to 60°C, preferably 25 to 40°C.
Knead with. [0037] Any kneading machine according to the present invention can be used, but a kneader is preferred among them, and a pressure kneader and a continuous kneader are particularly preferred. Specific examples include the MS type pressurized kneader manufactured by Moriyama Seisakusho Co., Ltd. and the KEX N-30 manufactured by Kurimoto Iron Works Co., Ltd. as a continuous kneader.
There is an extruder. [0038] The kneading method is a continuous type 2 shown in Figs. 1 and 2.
A shaft kneader will be explained as an example. In FIG. 1, first, powder 3 such as magnetic powder is introduced from the powder inlet 2 and transferred to the screw-type conveying means 4.
is sent to the kneading section 5, where it is sufficiently kneaded with the organic solvent solution 7 of the binder from the liquid inlet 6 under the action of shearing force, and further the organic solvent solution of the binder or the organic Together with the solvent 9, it is sent to a kneading and diluting section 11 by a screw type conveying means 10. Here, when there are several types of powder to be introduced, they are mixed uniformly by a mixer such as a V-type cone mixer or a W-type cone mixer, and then mixed by a powder quantitative supply device (screw feeder, rotary feeder, vibrating feeder, etc.). , belt feeder, etc.). Two parallel rotating shafts 12A, 1 shown in FIG.
2B, in the kneading section 5 and the kneading dilution section 11, paddles 13A, 13B, and 14A are rotatable in the same direction.
The kneading members 13 and 14 made of a combination of kneading members 13 and 14B are configured to apply a sufficient shearing force to the material to be kneaded. A pair of paddles 13A and 13B (or 14A
and 14B) are provided at different angles from each other, and the above shearing force is generated by rotating so that the tip of one paddle always rubs against the other paddle. Regarding the arrangement of the paddles, the angles formed by the front and rear paddles in the axial direction of a common rotation axis may be shifted by, for example, 45 degrees, and the phases of the left and right paddles can always be shifted by 90 degrees. In addition, various other arrangements of the paddles are possible. The kneading section 5 (or the kneading and diluting section 11 as the case may be) consists of a combination of a plurality of unit barrels 15, and the outer wall of each barrel is provided with a cooling water 16 for temperature adjustment. It has a double structure with a cooling water channel 19 between an inner wall 17 and an outer wall 18. In the figure, 20 is a cooling water inlet, 21 is a cooling water outlet, and each barrel 1
5, but the cooling water channels 19 are blocked between each barrel by a partition wall (not shown). Further, near the final position of each barrel 15 of the kneading section 5, as shown in FIG. 2, a sensor 22 for detecting the temperature of the kneaded material is arranged so as to face the inside of the barrel. . For example, a mercury type sensor or a thermocouple can be used as the sensor 22, but the detected temperature is processed by a control circuit section 23 such as a microcomputer, and a control signal for controlling the temperature of the cooling water 16 and its flow rate is generated. Output. However, since the temperature does not rise in the area of the screw-type conveying means 4 described above, cooling water 16 is passed through the kneading section 5 where the temperature rises (for each barrel 15), and the temperature of the kneaded material is detected at the final position. The cooling water temperature and its flow rate in the kneading section 5 are controlled by this. The kneaded material 24 obtained by the continuous twin-screw kneader 1 described above is introduced into a dilution/dispersion machine 25 equipped with stirring blades 30, as shown in FIG. 1, and is diluted by adding an organic solvent 26. be done. After that, the diluted dispersion liquid 27 enters the dispersion machine 28 equipped with a stirring plate 31, where it is dispersed, and if necessary, a curing agent, lubricant, organic solvent, etc. are added to form the magnetic paint 29.
It is sent to a coating section (not shown) as a coating material. Examples of the apparatus used for dilution and dispersion include those described in JP-A-64-79275, page 5, upper right column, line 7 to page 5, upper right column, line 10. [0047] As the above-mentioned dispersing machine 28, a ball mill,
A sand mill etc. can be used. When using a sand mill or the like, glass, alumina, zirconia, etc. can be used as the dispersion medium, and zirconia is preferable from the viewpoint of improving dispersibility. After the dispersion device 28, it is preferable to introduce the material through a filter to the application means. The subsequent steps (coating, orientation, drying, calendering) are carried out in the usual manner, so their explanation will be omitted. Examples of the coating means include those described in JP-A-3-49032, page 4, upper right column, line 20 to page 4, lower left column, line 7. The magnetic recording medium manufactured by the method of the present invention has a magnetic layer 42 laminated on one side of a non-magnetic support 41 and, if necessary, a back coat layer 43 on the back side, as shown in FIG. 3, for example. It is something that The magnetic layer 52 may be a single layer or a multilayer of two or more layers, and an overcoat layer (not shown) may be further provided if necessary. The magnetic layer coated on the magnetic recording medium produced by the method of the present invention has a dry film thickness of 0.5 to 2.
8 μm, preferably 0.5 to 2.0 μm. If the thickness is less than 0.5 μm, the electromagnetic conversion characteristics may deteriorate due to the thin film, or the adhesion may not be sufficient.
Easy to cause magnetic layer peeling. On the other hand, if the thickness exceeds 2.8 μm, the magnetic layer portion will increase, which will increase the cost of the medium itself. [Examples] Examples of the present invention will be described below along with comparative examples. Ingredients, proportions, order of operations, etc. may be varied without departing from the spirit of the invention. In addition, in the following examples, all "parts" are parts by weight. Examples 1 to 15, Comparative Examples 1 to 16 First, the following components were kneaded using a continuous or pressure kneading machine (However, Comparative Examples 13 and 15 were subjected to corona discharge treatment, and Comparative Examples 14 and 16 were subjected to easy treatment. Adhesion treatment is performed, and Comparative Examples 8 to 12 are examples in which kneading is not performed.) Co-γ-FeOx

100 carbon black
5
part α-Al2 O3

5 parts Vinyl chloride resin (Nippon Zeon MR110)
10 copies
polyurethane resin

Part 10 (Toyobo UP8700
30% by weight solution of methyl ethyl ketone/toluene)
Methyl ethyl ketone

Appropriate amount toluene

Appropriate amounts of this were diluted, stirred, and dispersed with the following components. cyclohexanone

Appropriate amount of methyl ethyl ketone
Appropriate amount
toluene

Appropriate amount of fatty acids


See Table 1 Butyl stearate

1.0 part [0055] Furthermore, a polyisocyanate compound (Coronate L:
A magnetic paint was prepared by adding 5 parts of Nippon Polyurethane Industries Co., Ltd., coated on a polyethylene terephthalate support, dried, and cut into 1/2 inch width to make a videotape. Details of the magnetic powder, fatty acids, etc. are shown in Table 1, and the results of performance evaluation are shown in Table 2. The method of each performance evaluation is as follows. (a) Magnetic layer peel test: A 90° peel tester shown in FIG. 4 was used. In advance, attach polyester tape for peeling (splice tape) to the magnetic layer so as not to introduce air bubbles, and use a hand roller to apply a load of approximately 5 kgf (49 N) to the magnetic layer in a fixed direction in the length direction (i.e., so as not to reciprocate). )
A test piece is prepared by rubbing and crimping 5 times. This test piece is fixed on a moving plate 51 on a testing machine, and the upper chuck 52 is moved vertically at a speed of 300±30 mm/min to peel off the splice tape 53 from the magnetic layer. At this time, peeling of the magnetic layer was 0 to 20%...○, peeling of the magnetic layer was 21 to 30%...Δ, and peeling of the magnetic layer was 31 to 100%...x. (b) Coefficient of dynamic friction: Measure the tape tension at the inlet and outlet of the head cylinder.005
8] (c) Dropout: Use a dropout counter VD-5M manufactured by Victor Japan, 10 μs or 3
Longer than μs and 14dB of Rf envelope output
The output that decreased by the above amount was regarded as one dropout, and the total length was measured, and the average value per minute was determined. (d) Powder removal from tape: The tape was run for 100 hours at a temperature of 40°C and humidity of 80% using a deck ("HR-6000" manufactured by Victor Japan Co., Ltd.), and V
The amount of magnetic powder adhered to the TR head was visually judged into the following three grades. ○: No powder falling △: Some powder falling ×: Significant powder falling 0060 (e) RF output: Using color video noise meter "Shibasoku 925 D/1",
Measurement was performed at a frequency of 6 MHz using a deck of "HR-S7000" manufactured by Victor Company of Japan. [0061]
Table-1A Magnetic powder
FeOx fatty acid addition amount (wt
%) Magnetic layer thickness
X= BET value Myristic acid Oleic acid Stearic acid (μm)────────
──────────────────────────
---Example 1 1.38 30
1.5-
1.0 2.5 2
1.38 30 2.0
-2.0
2.5 3 1.38 3
0 3.0 -
3.0 2.8
4 1.38 40 2
．． 0 -
2.0 2.5 5 1.
38 50 2.0
-2.0
2.5 6 1.38 30
2.0 2.0
-2.5
7 1.38 30 2.0
-2
．． 0 0.5 8 1.38
30 2.0
-2.0
2.0 9 1.38 30
2.0 -
2.0 2.8
10 1.45 30 2.0
-2.
0 2.5 11 1.45
30 2.0
-2.0
2.5 12 1.38 30
1.0 2.0
1.0 2.8
13 1.48 30 2.
0 -
2.0 2.5 14 1.
34 30 2.0
-2.0
2.5 15 1.38 30
1.5-
1.5 2.5 *In Examples 11 and 12 and Comparative Example 3, a pressure kneader (manufactured by Moriyama Seisakusho Co., Ltd.) was used for kneading, and in other examples, a twin-screw continuous kneader (manufactured by Kurimoto Iron Works Co., Ltd.) was used for kneading. A KEX kneader (manufactured by Yokohama) was used. [0062]
Table-1B Magnetic powder
FeOx fatty acid addition amount (wt
%) Magnetic layer thickness
X= BET value Myristic acid Oleic acid Stearic acid (μm)────────
──────────────────────────
---Comparative example 1 1.38 30
1.0 -
1.0 4.0 2
1.45 30 1.0
-1.0
4.0 3 1.38 3
0 1.0 -
1.0 4.5
4 1.38 30 0
．． 5-
0.5 2.5 5 1.
38 30 1.0
-1.0
2.5 6 1.38 30
3.5-
3.0 2.5
7 1.50 30 1.5
-1
．． 0 2.5 8 1.38
30 1.0
-1.0
2.5 9 1.38 30
1.5-
1.5 2.5
10 1.34 30 2.0
-2.
0 2.5 11 1.45
30 2.0
-2.0
2.5 12 1.50 30
1.5-
1.0 2.5
13 1.38 30 1.0
-1
．． 0 2.5 14 1.3
8 30 1.0
-1.0
0.5 15 1.38 30
1.5-
1.0 2.5
16 1.38 30 1.
5-
1.0 1.0 0063
Table 2A Magnetic layer peeling Dynamic friction coefficient Dropout Tape powder drop RF output────────────────────
──────────────────Example 1
○ 0.25
4/7 ○
+2.0 2 ○
0.20 5/6
○ +1.8
3 ○ 0.18
4/5
○ +1.5 4
○ 0.22
5/8 ○
+2.8 5 ○
0.22 7/8
○ +3.6
6 ○ 0.1
9 6/8
○ +1.9 7
○ 0.24
3/5 ○
+1.5 8 ○
0.23 5/9
○ +1.8
9 ○ 0.
20 5/7
○ +2.1 10
○ 0.19
6/8 ○
+2.2 11 ○
0.19 5/
8 ○ +2
．． 5 12 ○
0.19 4/6
○ +2.4
13 ○ 0.21
5/8 ○
+2.4 14
○ 0.20
4/7 ○
+2.0 15 ○
0.23 4/10
○ +2.3 0064
Table 2B Magnetic layer peeling Dynamic friction coefficient Dropout Tape powder drop RF output────────────────────
──────────────────Example 1
× 0.34
25/42 ×
+2.1 2 △
0.24 17/35
△ +2.0
3 △ 0.26
15/37
△ +2.6 4
×0.38
32/51 ×
+2.7 5 ×
0.32 29/48
× +2.5
6 ○ 0.4
5 50/77
○ -1.8 7
○ 0.24
Tape not running 8
× 0.33
35/56 ×
+0.2 9 ○
0.23 9/16
○ ±0
10 ○ 0
．． 20 11/18
△ -0.1 1
1 ○ 0.20
10/15 △
-0.2 12
○ 0.23 11
/16 △
±0 13 ○
0.33 21/33
○ +1.9
14 ○ 0.32
7/11 ○
+1.6 15
○ 0.27
42/63 ○
+1.6 16 ○
0.25 21/34
○ -0.5 [0065] As shown in Table 2, the magnetic tape of this example has no peeling of the magnetic layer or powder falling off of the tape, and has excellent planar smoothness, so dropouts are small and electromagnetic conversion is It has high characteristics.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a kneading and dispersion process using a twin-screw kneader.

FIG. 2 is a sectional view of the kneading section of the twin-screw kneader.

FIG. 3 is an example of a cross-sectional view of a magnetic recording medium.

FIG. 4 is a conceptual diagram of a 90° peel tester.

[Explanation of symbols]

1 Continuous twin-screw kneader (kneader) 2 Powder input port 3 Powder 4, 10 Screw type conveyance means 5 Kneading sections 6, 8 Inlet 7 Binder solution 9 Binder solution or organic solvent 11 Kneading dilution section 12, 12A, 12B Rotating shaft 13, 13A, 13B, 14, 14A, 14B
Paddle 15 Barrel 16 Cooling water 19 Cooling water channel 22 Temperature detection sensor 23 Control circuit section 24 Kneaded material 25 Dilution disperser 28 Disperser 41 Support 42 Magnetic layer 43 Back coat layer 51 Moving plate 52 Upper chuck 53 Splice tape

Claims (1)

[Claims] Claim 1: A method for producing a magnetic recording medium, comprising a magnetic layer containing magnetic powder and a fatty acid provided on a support, comprising:
The support was not pretreated to improve adhesion, and F
Magnetic powder made of cobalt-containing iron oxide represented by eOx (where x is 1.34 to 1.48) and the magnetic powder
A step of kneading a magnetic coating composition containing 2.5 to 6.0 parts by weight of the fatty acid per 100 parts by weight is provided, and the dry film thickness of the magnetic layer coated on the support is provided. A method for manufacturing a magnetic recording medium, characterized in that the thickness of the magnetic recording medium is 0.5 to 2.8 μm.