JP3146906B2 - Manufacturing method of magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a floppy disk,
The present invention relates to a method of manufacturing a magnetic recording medium such as an audio tape and a video tape, and more particularly, to a method of manufacturing a magnetic recording medium capable of obtaining a high output in recording / reproducing characteristics and recording at a high density.

[0002]

2. Description of the Related Art Generally, a magnetic recording medium is produced by the following method. First, a magnetic paint mainly composed of a magnetic powder and a binder resin is applied to the upper surface of the non-magnetic support in the traveling direction, and a magnetic field is applied to the magnetic powder by a permanent magnet or a solenoid while the magnetic paint is not dried. The orientation treatment is performed, and the magnetic paint is dried and cured to form a magnetic layer on the non-magnetic support. In a method of manufacturing a magnetic recording medium including such a coating and drying step,
The formation of the magnetic layer on the nonmagnetic support is usually performed on the upper surface side (the surface opposite to the direction of gravity) of the nonmagnetic support running parallel to the ground surface.

In a magnetic recording medium manufactured by such a manufacturing method, the thickness of the magnetic layer is 1.0 μm to 5.0 μm.
7, the distribution of the magnetic powder 102 in the magnetic layer 101 is sparse on the surface side of the magnetic layer 101 and dense on the contact surface between the nonmagnetic support 103 and the magnetic layer 101, as shown in FIG. A phenomenon has occurred. This is because, in the magnetic paint to be applied, the magnetic powder 10
It is considered that the magnetic powder 102 sinks by weight before the magnetic paint dries and hardens because the specific gravity is higher in No. 2.

[0004]

In recent years, high-density recording of magnetic recording media has been promoted, and high-coercive force and high orientation of magnetic powder, thinning of a magnetic layer, and improvement of spacing loss have been developed. Techniques such as ultra-smooth surface treatment by the development of a compression calender have been developed. Further, in a magnetic recording medium, the recording wavelength becomes shorter as the recording density becomes higher, and as the recording wavelength becomes shorter, it becomes more difficult to penetrate into the magnetic layer, and only the surface portion of the magnetic layer is magnetized. Therefore,
In order to realize high-density recording on a magnetic recording medium, it is necessary to increase the density of the magnetic powder in the surface portion of the magnetic layer.

[0005] For this purpose, a method of increasing the packing density of the magnetic powder in the magnetic layer as a whole has been considered. The magnetic layer is more strongly compressed by a high compression calender to make the distribution of the magnetic powder uniform and high density. And attempts to increase the ratio of the magnetic powder to that of the binder resin have been made. However, such a method rather complicates the process and raises the manufacturing cost. Therefore, it has been desired to improve the recording / reproducing characteristics of the magnetic recording medium by increasing the density of the magnetic powder in the surface layer portion of the magnetic layer instead of increasing the packing density of the magnetic powder in the magnetic layer as a whole.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention provides a method for manufacturing a semiconductor device, comprising the steps of:
A step of applying a liquid magnetic paint composed of magnetic powder and a binder resin, a step of turning the nonmagnetic support upside down with the surface on which the magnetic paint is applied downward, and a step of turning the nonmagnetic support upside down, Applying a magnetic field to the magnetic paint applied to the substrate to orient the magnetic powder; and drying and curing the magnetic paint applied on the non-magnetic support. Is provided.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, after a magnetic paint is applied on a non-magnetic support, the surface to which the magnetic paint is applied is directed in the direction of gravity, and then dried and cured. That is, unlike the conventional manufacturing method, the magnetic powder in the magnetic paint is concentrated on the surface of the magnetic layer under the influence of gravity, thereby increasing the density of the magnetic powder on the surface of the magnetic layer. It is a manufacturing method.

Hereinafter, a method for manufacturing a magnetic recording medium according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic view showing a method for manufacturing a magnetic recording medium according to the present invention. In FIG. 1, a roll 2 of a non-magnetic support 1 wound as a belt-like film is sent out from an unwinding unit in a traveling direction A,
In the coating device 3, a magnetic paint is applied to the upper surface of the non-magnetic support 1 to form a magnetic layer 4. Here, the traveling direction A is a direction parallel to the ground surface. A reversing device 5 is provided on the traveling direction A side from the coating device 3, and the direction of the magnetic layer 4 and the non-magnetic support 1
Of the magnetic powder in the magnetic layer 4 is concentrated on the surface thereof.

Further, downstream of the traveling direction A, the magnetic layer 4
A magnetic field is applied to the magnetic layer 4 to orient the magnetic powder in the magnetic layer 4. Downstream of the orienting device 6, there is further provided a drying device 7, in which the oriented undried magnetic layer 4 is dried and hardened, and the sheet-shaped magnetic recording medium 8 is wound into a roll at a winding section. Taken.

The above-mentioned coating apparatus 3 can be applied to all coating apparatuses such as a gravure coater, a reverse roll coater, a kiss coater and a slot die coater. In the above-described embodiment, the orienting device 6 and the drying device 7 are separate devices, but may be a single device that is an integrated device that simultaneously performs orientation and drying.

The orientation device 6 applied in the present invention comprises:
A series or multiple DC solenoid type orientation device may be used, a permanent magnet type orientation device may be used, or a combination type of a permanent magnet and a DC solenoid type orientation device may be used. Further, the present invention provides a magnetic powder in which the magnetic powder in the magnetic paint has a needle-like shape and the axis of easy magnetization is not only in the in-plane direction of the coating surface, but also in the direction of the easy axis of magnetization such as hexagonal crystalline magnetic powder such as barium ferrite. However, the present invention can also be applied to a method for manufacturing a magnetic recording medium in the perpendicular direction. The drying device 7 may be an air floating type or an air cap type hot air jet type, or may be an infrared curing type or an ultraviolet curing type.

Referring to the specifications of the apparatus described with reference to FIG. 1, the distance L1 (m) from the reversing device 5 to the drying device 7 is described.
Is

L1 ≧ V / 60 V: coating speed (m / min)

It is desirable that This indicates that irrespective of the application speed, the magnetic powder in the applied magnetic paint must be affected by gravity for at least one second or more. Further, a distance L2 between the coating device 3 and the reversing device 5
The length L3 in the reversing device 5 is desirably as short as possible so that the applied magnetic paint does not dry in the upward state.

The orientation magnetic field of the orientation device 6 used in the present embodiment has a horizontal magnetic field of 0 to 8 kOe and a vertical magnetic field of 0 to 8 kOe.
e, and a DC solenoid system which holds the magnetic field e, and the magnetic field can be applied individually and simultaneously. Also, the drying device 7 can be individually set in a range of 70 to 150 degrees by applying a temperature gradient to the drying temperature by an air floating method separated into a plurality of zones (three divisions). 0 to 20 m / min, 0 to ³ m ³
/ Min.

The magnetic recording medium to which the present invention is applied is a coating type magnetic recording medium, and the magnetic powder in the magnetic layer applied to the non-magnetic support is a conventionally known magnetic recording medium.
You are not bound at all. For example, γ-Fe ₂
Iron oxide magnetic powders such as O ₃ , Co-containing γ-Fe ₂ O ₃ , Fe ₃ O ₄ , and Co-containing Fe ₃ O ₄ : Fe, Ni, Co, Fe
-Ni-Co alloy, Fe-Ni alloy, Fe-Al alloy,
Fe-Al-Ni alloy, Fe-Al-Co alloy, Fe-
Mn-Zn alloy, Fe-Ni-Zn alloy, Fe-Al-
Ni-Co alloy, Fe-Al-Ni-Cr alloy, Fe-
Al-Co-Cr alloy, Fe-Co-Ni-Cr alloy,
Fe-Co-Ni-P alloy, Co-Ni alloy, etc., Fe,
Ferromagnetic powder such as metal magnetic powder mainly composed of Ni, Co, etc .;
Magnetic powders such as hexagonal ferrites such as aFe ₁₂ O ₁₉ are exemplified.

Next, a specific example of the reversing device 5 as a main part of the present invention will be described with reference to FIG. 2A is a schematic side view of the reversing device 5 viewed from the right side, FIG. 2B is a schematic top view of the reversing device 5, FIG. 2C is a schematic side view of the reversing device 5 viewed from the left side, FIG. 2D is a schematic front view of the reversing device 5.

In FIG. 2 (d), a recording medium 10 having a magnetic coating applied to the upper surface of a non-magnetic support is transported in the direction of the arrow, and is transported on a transport roller 15 having a rotation axis perpendicular to the running direction. And inserted into the reversing device.
2B, the lower conveying roller 1 having a rotation axis in a direction inclined by 45 degrees with respect to the running direction of the recording medium 10 is shown.
3, the running direction of the recording medium 10 can be changed by 90 degrees (upward in the figure). Then, as shown in FIG.
The path of the recording medium 10 is transferred from a transport roller 11 via a transport roller 12 to a top section of the apparatus, which is provided so as to be perpendicular to the traveling direction and parallel to the lower part and the upper part of the apparatus. And, with respect to the running direction of the recording medium 10,
The recording medium 10 is tilted by 5 degrees and has a rotation axis inclined by 90 degrees with respect to the conveying roller 13.
Means that the vehicle travels again with the front and back reversed while the traveling direction is the same as the first.

Therefore, when the magnetic paint is first applied to the upper surface of the non-magnetic support, the reversing device can be used to reverse the magnetic paint so that the surface on the magnetic paint side is directed in the direction of gravity. In addition, since all of the transport rollers 11 to 15 are in contact with the non-magnetic support side, they do not affect the magnetic paint that has not been dried yet, and the rollers do not become dirty.

Each of the transport rollers 11 to 15 is a recording medium 10
The rotation in synchronization with the traveling speed of is controlled by the motor 20. The rotation direction of each transport roller is controlled clockwise because the transport roller 14 is reversed, and the other direction is controlled counterclockwise.

Here, the transport rollers 11 and 12 are three-dimensionally parallel in the height direction, and by adjusting the distance between the two, the traveling height of the recording medium 10 can be adjusted. The route can be set smoothly. In addition, although two rollers are arranged as the conveying rollers 11 and 12, one roller having a diameter corresponding to the height to be changed may be used. The positions of these rollers in the vertical direction in the figure (distances from the conveying rollers 13 and 14) may be appropriately determined according to the space in the apparatus.

Next, the positional relationship between the transport rollers 13 and 14 will be described. The height of the transport rollers 13 and 14 may be set so as not to hinder the running of the recording medium 10 and the rotation of each roller. Further, by moving the rotation axis of the conveyance roller 90 by 90 degrees in the horizontal direction with respect to the conveyance roller 13 and installing the conveyance roller 14 at a position where the conveyance roller 14 is moved in parallel in the vertical direction, the entry direction and the ejection direction of the recording medium 10 match. Can be done. Due to this, in the middle of a group of magnetic recording medium manufacturing apparatuses, many of which are conventionally linearly arranged,
When the reversing device is added, it is particularly effective in that a large-scale layout change of the device group does not occur and the installation becomes easy.

Further, as shown in FIG.
If the recording medium 3 is shifted by 45 degrees with respect to the direction of entry of the recording medium 10, the direction of the recording medium 10 changes by 90 degrees, and the subsequent transport rollers 11, 12 can be installed in parallel with the direction of entry. Each roller can be housed in a rectangular parallelepiped shape, and can be downsized, which is the most preferable.

The transport roller 15 adjusts the position of the recording medium 10 when it enters the apparatus.
For example, as shown in FIG. 2, when the apparatus enters from below the apparatus, the height of the conveying roller 13 and the path thereof are adjusted so that the recording medium 10 can be smoothly moved so that no excessive force acts on the recording medium 10. And has a function of a support roll for maintaining running stability.

In this embodiment, the transport rollers 11 to 15 use metal rolls, but may use non-metal rolls.
Various ceramics, various resins, metallized resins, metal fiber-filled reinforced resins, and metal rolls coated with the above materials may be used. Furthermore, what used the sintered roll of various ceramics and various aluminum may be used. In the case of a conveying roller using a sintering roll, the structure shown in FIG. 3 was used and dried from one side (oil mist was completely removed).
A method in which industrial compressed air is introduced and the nonmagnetic support is floated from each roller and run by utilizing the pressure of air that escapes from the surface of the sintering roll may be used. in this case,
Compressed air is preferably in the range of 3 to 10 kg / cm ² , especially 5
Experiments have shown that が 7 kg / cm ² is particularly good.

The diameter of the transport roller is set to 30 to 150 in order to reduce the running tension load of the recording medium 10 traveling in the reversing device of the present invention.
It has been clarified by experiments that the range of mm is good.

Next, the results of an example manufactured by the method for manufacturing a magnetic recording medium of the present invention will be verified. (Example 1) <Magnetic coating composition> Acicular metal magnetic powder 100 parts by weight Vinyl chloride resin 12 parts by weight Polyurethane resin 13 parts by weight Polyisocyanate 5 parts by weight Abrasive (alumina powder) 5 parts by weight Myristic acid 1 part by weight Parts carbon black 1 part by weight toluene 100 parts by weight cyclohexanone 120 parts by weight

The acicular metal magnetic powder has a major axis length of 0.1 μm, a single axis length of 0.04 μm and a coercive force of 1900O.
e. Using a material having a saturation magnetization of 130 (emu), the above composition was dispersed in a sand glass mill for 48 hours to prepare a magnetic paint. This magnetic paint was applied to a PET film as the non-magnetic support 1 using a gravure coater under the following paint conditions.

<Coating Conditions> Thickness of coating layer: 3.0 μm Coating speed: 30 m / min PET film: 10 μm

<Orientation Conditions and Drying Conditions> Orientation device: DC solenoid / DC magnetic field 6000 Oe Drying device: Temperature 80 ° C., Air speed 10 m / min, Air volume 3 m ³ / min Air floating

Under the above conditions, a magnetic paint is applied to the non-magnetic support using the apparatus shown in FIG. 1, then mirror-finished by calendering, cut into 1/2 inch tapes through a curing step, and The magnetic tape of Example 1 was produced.

(Comparative Example 1) The conditions for producing the magnetic tape were the same as in Example 1, except that the magnetic layer 4 was inverted without the intermediary of the inverting device 5 in the apparatus shown in FIG. It was prepared by a conventional method that does not allow it. Example 2 The conditions for producing the magnetic tape were the same as those in Example 1, except that the thickness of the coating layer was 0.1 μm. (Comparative Example 2) The conditions for producing the magnetic tape were the same as those in Example 1, except that the thickness of the coating layer was 0.1 μm, without using the reversing device 5 in the apparatus of FIG. .

The results of testing the above four examples are shown.
FIG. 4 is a graph showing the recording and reproducing characteristics of Example 1 and Comparative Example 1, and FIG. 5 is a graph showing the recording and reproducing characteristics of Example 2 and Comparative Example 2. As can be seen from FIGS. 4 and 5, it was confirmed that the reproduction outputs of Examples 1 and 2 of the present invention were improved over Comparative Examples 1 and 2 over the entire recording frequency range.

FIG. 6 is a table showing the filling degree of magnetic powder in each layer of the magnetic layer in Comparative Example 1 and Example 1. From the magnetic layer cross-sectional photograph at a magnification of 48,000 times by an electron microscope, the filling degree of the magnetic powder was measured at three points of the surface, the middle layer and the lower layer of the magnetic layer, and the average number of magnetic powder per unit area pcs / cm ²
Is represented. As is clear from FIG. 6, the distribution of the magnetic powder in the magnetic layer of Example 1 was more concentrated on the surface of the magnetic layer than in Comparative Example 1, and the packing density of the magnetic powder on the surface of the magnetic layer was lower than that of Example 1. It can be seen that the improvement is 1.3 times that of Example 1.

[0037]

As described in detail above, the method for producing a magnetic recording medium according to the present invention is characterized in that, after the magnetic paint is applied to the non-magnetic support, the surface coated with the magnetic paint is dried before the magnetic paint is dried. Is directed in the direction of gravity, the magnetic powder in the magnetic paint is affected by gravity, and the magnetic powder distribution in the formed magnetic layer can be concentrated on the surface. Therefore, the magnetic powder on the surface of the magnetic layer required for a high-density magnetic recording medium can be made denser, and the recording and reproducing characteristics can be improved. In addition, even in a conventional manufacturing process of applying a magnetic paint from the upper surface of a non-magnetic support, it is only necessary to add a reversing process after the process of applying the magnetic paint, so a large-scale equipment change is performed. There is a practically excellent effect that it is not necessary.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for manufacturing a magnetic recording medium of the present invention.

FIG. 2 is a diagram showing a specific example of a reversing device 5 which is a main part of the present invention.

FIG. 3 is a view showing a structure of a combustion roll.

FIG. 4 is a graph showing recording and reproduction characteristics of Example 1 and Comparative Example 1.

FIG. 5 is a graph showing recording / reproducing characteristics of Example 2 and Comparative Example 2.

FIG. 6 is a table showing the filling degree of magnetic powder in each layer of the magnetic layer in Comparative Example 1 and Example 1.

FIG. 7 is a diagram showing a distribution of magnetic powder in a magnetic layer in a magnetic recording medium according to a conventional manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-magnetic support 3 Coating device 4 Magnetic layer 5 Inversion device 6 Orientation device 7 Drying device 8 Magnetic recording medium

Claims (1)

(57) [Claims] 1. A step of applying a liquid magnetic paint composed of magnetic powder and a binder resin on an upper surface of a non-magnetic support, wherein the surface on which the magnetic paint is applied is on a lower side, and the non-magnetic support is on an upper side. Flipping the magnetic paint applied on the non-magnetic support, applying a magnetic field to the magnetic paint applied on the non-magnetic support, and orienting the magnetic powder; drying and curing the magnetic paint applied on the non-magnetic support A method of manufacturing a magnetic recording medium.