JPH01201824A - Manufacture of magnetic recording medium and device therefor - Google Patents

Abstract

PURPOSE:To sufficiently eliminate a micro projection without increasing the tensile force of a recording medium by traveling and grinding a magnetic layer as pressing on a specific grinding wheel after smoothing the magnetic layer. CONSTITUTION:Grinding is performed by pressing the surface of the magnetic layer 4 of the recording medium 2 in which magnetic coating is applied on a base film 3 and a smoothing processing is applied on the grinding wheel 1 in which a grinding material with high hardness is formed on the surface of a circumference by a pressing means (A) and traveling it. And it is desirable to wind the layer 4 on the wheel 1 at a winding angle theta of 30-300 deg., and to press by applying the tensile force of 50-1,000g/inch width by using a belt-shape material as the means A. Also, it is desirable to rotate the wheel 1 at circumferential speed of 0-700m/min, and to travel the medium at speed of 20-500m/min, and also, to form the circumferential surface of the wheel 1 with diamond abrasive grain, or ceramics with constant hardness and grain size.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and apparatus for manufacturing a magnetic recording medium, and more specifically to a magnetic recording medium having a magnetic layer with good surface smoothness and excellent electromagnetic conversion characteristics. This article relates to an efficient manufacturing method and device.

[Prior Art] Generally, magnetic recording media such as magnetic tapes are made of magnetic powder,
A magnetic coating consisting of a binder component, an organic solvent, and other necessary components is applied onto a base film to form a magnetic layer, which is then subjected to magnetic field orientation treatment, drying treatment, and surface smoothing treatment, and then shaped into the desired shape. It is broken by cutting.

In recent years, the demand for high-density recording has increased for such magnetic recording media, and in response to the high-density recording, ultrafine particles of cobalt-containing γ-Fe, 03 powder and ferromagnetic metal powder are used to achieve high storage stability. In addition to increasing the magnetism, the surface of the magnetic layer is also smoothed.

However, ultrafine cobalt-containing T-Fe20
3 powder and ferromagnetic metal powder are more difficult to disperse as they become finer particles, and even if they are dispersed, they tend to re-agglomerate if left undisturbed, and they are also mixed into the magnetic layer with these magnetic powders. Solid additives also have a similar tendency. However, when a magnetic paint containing such easily agglomerated magnetic powder or solid additives is applied onto a base film, a magnetic layer with convexities is formed on the surface, and these convexities cause localized damage during recording and playback. There are disadvantages such as signal loss and many dropouts.

Therefore, in order to correct such convexities on the surface of the magnetic layer and suppress the occurrence of dropouts, the magnetic layer formed on the substrate is subjected to surface smoothing treatment, and then rotated in the opposite direction to the running direction of the magnetic recording medium. The surface of the magnetic layer is polished by winding it around a polishing wheel. (Unexamined Japanese Patent Publication No. 172532/1982) [Problem to be Solved by the Invention] However, simply wrapping a magnetic recording medium around a polishing wheel that rotates in the opposite direction and causing it to run will cause the influence of the air layer that enters as the surface layer of the magnetic recording medium increases. A gap is created between the polishing wheel and the magnetic recording medium, and a gap is created in the magnetic recording medium, making it impossible to remove minute protrusions protruding from the surface of the magnetic layer. This tendency is particularly noticeable when the magnetic layer has a relatively soft composition, and when the tension of the running magnetic recording medium is increased to expel the air layer, permanent deformation occurs in the magnetic recording medium and the running becomes unstable. The reproducing magnetic head does not run over the recorded track accurately (skewing problems, etc.) are likely to occur.In addition, in this conventional polishing process, after slitting, the magnetic head is wound once again and then polished again. There are disadvantages such as an increase in production costs and an increase in production costs.

[Means to solve the problem]

This invention was made as a result of various studies in order to eliminate the drawbacks of the prior art, and involves applying a magnetic paint onto a base film, and then smoothing the magnetic layer formed by this application. After that, the tension of the magnetic recording medium is increased by polishing the smoothed magnetic layer surface by running it on a polishing wheel whose peripheral surface is made of an abrasive material with high hardness while being pressed by a pressing means. This method sufficiently removes minute protrusions without causing any problems and effectively suppresses the occurrence of dropouts.

After smoothing the surface of the magnetic layer, the original magnetic recording medium is cut into a predetermined width, and at the same time, the surface of the cut magnetic layer is polished to reduce the tension in the magnetic recording medium. This polishing process is designed to sufficiently remove minute protrusions without polishing, suppress the occurrence of dropouts, and perform this polishing process with high efficiency.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a polishing wheel whose circumferential surface is made of a grinding material with high hardness. Wrapping is carried out at an angle θ, and numeral 5, which runs in the direction of arrow A, is a band-like material made of woven or non-woven fabric that presses the magnetic recording medium 2 against the polishing wheel 1, and applies a predetermined tension shown by arrow T. In this way, the magnetic recording medium 2 that is being wound around the polishing wheel 1 and traveling is pressed from the base film 3 side. Reference numeral 6 denotes a leaf spring that further presses the strip 5 against the magnetic recording medium 2 and the polishing wheel 1. The plate spring 6 is fixed by a support 7 and presses the strip 5 against the magnetic recording medium 2 with a predetermined elastic force.
is pressed against the polishing wheel l.

According to the magnetic recording medium polishing apparatus 8 constructed in this way, the magnetic layer 4 coated on the base film 3 of the magnetic recording medium 2 is formed by applying the magnetic layer 4 to the strip 5 and the leaf spring 7.
While being sufficiently pressed by the polishing wheel 1, the peripheral surface is polished by the polishing wheel 1, which is made of a highly hard abrasive material. is sufficiently removed and the surface of the magnetic layer is polished. As a result, a magnetic layer with excellent surface smoothness is formed, and a magnetic recording medium with excellent electromagnetic conversion characteristics is obtained.

Here, it is preferable that the peripheral surface of the polishing wheel 1 of the polishing device 8 has a hardness of 9 or more on the Mohs hardness scale, and if the Mohs hardness is 8 or less, there is almost no polishing effect on the magnetic layer containing additives such as alumina. I can't. Further, the peripheral surface of the polishing wheel l is preferably formed of abrasive grains with a grain size of #1500 to #4000, and the grain size is preferably 415
If the particle size is less than 0.00, the surface roughness becomes too large and the magnetic layer is likely to be scratched, and if the particle size exceeds #4000, the polishing effect will be extremely reduced. The peripheral surface of such a polishing wheel 1 has a Mohs hardness of 9 or more and a grain size of #1500 to #40.
00 ceramic is integrally molded on the peripheral surface of the polishing wheel body, or the Mohs hardness is 9 or more and the grain size is #150.
0 to #4000 abrasive grains are sintered to the circumferential surface of the polishing wheel body, and the Mohs hardness is 9 or more and the grain size is #150.
It is formed by applying abrasive grains of #0 to #4000 to the circumferential surface of the polishing wheel body with a binder resin, and the polishing abrasive grains include, for example, diamond, boron carbide, silicon carbide,
Aluminum oxide and the like are preferably used.

Further, the magnetic recording medium 2 is produced by winding the magnetic layer 4 around the polishing wheel 1 so that the angle θ is within the range of 30 to 300 degrees, and further pressing the magnetic recording medium 2 onto the polishing wheel l. It is preferable that the strip 5 made of woven fabric or non-woven fabric is pressed against the magnetic layer 4 of the magnetic recording medium 2 by applying a tension of 50 to 10100 O/1 inch width in the direction shown by the arrow T. If the winding angle θ is smaller than 30 degrees, the magnetic layer 4 cannot be polished well;
This is physically difficult due to guide rolls and the like, and also increases the meandering of the magnetic recording medium. Furthermore, if the tension of the strip is less than 50 gf/1 inch width, there will be no polishing effect, and if it is greater than 1000 gf/1 inch width, a large tension will be required to run the magnetic recording medium 2, which may cause permanent deformation. be.

Further, the plate spring 6 that further presses the strip 5 made of woven or non-woven fabric that presses the magnetic recording medium 2 against the polishing wheel 1 is preferably pressed with a pressing force of 10 to 100 gf/1 inch width. If the pressing force is smaller than 1 inch width, the polishing effect will be small, and if the pressing force is thicker than 1008 f/1 inch width (then the magnetic layer 4 will be more likely to be scratched).

Incidentally, if the magnetic recording medium 2 can be sufficiently pressed against the polishing wheel 1 with the band-like material 5 made of woven or non-woven fabric, the leaf spring 6 is not necessarily required.

The polishing wheel 1 may also be rotated, e.g.
If the magnetic recording medium 2 is rotated in a direction opposite to the running direction A as shown by arrow B, the surface of the magnetic layer 4 can be polished more effectively and good results can be obtained.

In this way, when rotating the polishing wheel 1, it is preferable to rotate the polishing wheel 1 at a circumferential speed of 1 to 700 m/min, and to run the magnetic recording medium 2 at a running speed of 20 to 500 m/min. If the speed of the polishing wheel 1 and the magnetic recording medium 2 is slower than this range, the polishing effect will be small and the air layer between them will become too thick, making polishing impossible.

FIG. 2 shows an example in which such a magnetic recording medium polishing device 8 is attached to a cutting device, and the magnetic recording medium material 21 wound around the material roll 9 is cut. Device 1
After being cut into a predetermined width by a pair of cutters 11 of 0, the magnetic tape 22 is divided into two groups by a pair of guide rolls 12, and several strips of magnetic tape 22 in each group are led to a polishing device 8 and polished.
It is wound up on a roll 13 to be wound up. In this case, after cutting the magnetic tape 22, the magnetic tape 22 is subsequently polished. Therefore, the polishing process of the magnetic tape 22 can be performed efficiently, and the surface smoothness of the magnetic layer is good, and the magnetic tape 22 is polished. A magnetic tape 22 with excellent conversion characteristics can be obtained efficiently.

As the magnetic powder used in this invention, for example, 7
-Fe, O8 powder, Fe30m powder, 1-Fe containing CO
, O, powder, Co-containing Fe, 0° powder, Cry, powder 1
, Fe powder, Co powder, and other conventionally known magnetic powders, and binder resins include vinyl chloride-vinyl acetate copolymers, polyvinyl butyral resins, cellulose resins, polyurethane resins, and polyester resins. Conventionally used binder resins such as isocyanate compounds are widely used.

Further, as the organic solvent, conventionally widely used organic solvents such as toluene, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, and ethyl acetate are used alone or in a mixture of two or more.

Furthermore, the coating machines that apply the magnetic paint prepared by mixing and dispersing these magnetic powders, binder resin, organic solvent, etc. onto the base film include knife coaters, gravure coaters, reverse roll coaters, and bead coaters. , Kiss coater, Gui coater, Curtain coater, and other conventionally used coaters are preferably used.

Note that various commonly used additives such as dispersants, lubricants, abrasives, antistatic agents, etc. may be optionally added to the magnetic paint.

〔Example] Next, embodiments of the invention will be described.

Example I Co-containing -Fe, 03 magnetic powder 100 parts by weight (specific surface area 40 cities/g) Nitrocellulose (manufactured by Asahi Kasei Co., Ltd. 10, HIGI) Polyurethane (manufactured by Gutdrich Co., Ltd. 9, Nissan 5702) Polyisocyanate (Japan) Poly I〃Made by Urethane Co., Ltd., Coronated) α-Alumina 2〃Carbon black 5 “Zinc stearate
0.5 n-butyl stearate 0
．． 5〃Cyclohexanone 80〃Methyl ethyl ketone 80〃Toluene
80 This composition was sufficiently mixed and dispersed in a ball mill until it became uniform to obtain a magnetic paint A. Furthermore, a magnetic coating material B was obtained with the same composition but with a slightly shorter crosstalk dispersion time and in which aggregates remained. Next, magnetic paint A and magnetic paint B were mixed to obtain magnetic paint C in which a slight amount of aggregate remained intentionally. This magnetic paint C is applied onto a 14 μm thick polyethylene terephthalate film support using a gravure roll coater so that the magnetic layer has a thickness of 5 μm, and then subjected to an orientation treatment. After drying, it is further mirror-finished using a super calender. A magnetic tape original fabric was obtained.

Next, as shown in FIG.
It was run at a running speed of 50 m/min, cut into 12.65 mm width by the cutter 11 of the cutting device 10, and divided into two groups.
Five strips of the magnetic tape 22 were polished by the polishing device 8. Polishing with this polishing device 8 is carried out by polishing a polishing wheel 1 with a diameter of 100 m using diamond with a grain size of #2000.
The magnetic tape 2 is rotated in the direction of arrow B at a circumferential speed of m/min.
2 is run in the direction of arrow A with a tension of 100 gf/1 inch width and the winding is at an angle of 060 degrees, and the non-woven fabric 5 is wrapped with a tension of 4.0
Grind the magnetic layer 4 with the wheel 1 with a tension of 0 gf/1 inch width.
, and the pressing with the leaf spring 6 was omitted.

Example 2 In the polishing process in the polishing device 8 in Example 1, diamonds with a particle size of #2000 were used and the diameter was 100+.
In place of polishing wheel 1 of ++ m, A with an average particle size of 5 μm
PZ 03 powder was formed on the circumferential surface of the polishing wheel body to a thickness of 0.3 m by thermal spraying, and the surface roughness was finished to 1 μm Ra with a center line average roughness. The particle size was #2000 and the diameter was 1 μm.
Polishing was carried out in the same manner as in Example 1, except that a 00Kaku polishing wheel 1 was used, a nylon woven fabric was used instead of the nonwoven fabric, and the magnetic layer 4 was pressed against the polishing wheel 1 with the same tension.

Example 3 In the polishing process in the polishing device 8 in Example 1, the tension of the nonwoven fabric 5 was increased from 400 gf/1 inch width to 200 gf.
/1 inch width, and the nonwoven fabric 5 was fixed at 20 gf using a leaf spring 6 made of a 0.2 mm thick polyester film.
The polishing process was performed in the same manner as in Example 1, except that the pressure was applied with a tension of /1 inch.

Embodiment 4 In Embodiment 1, the magnetic tape cut by the cutter 11 of the cutting device 10 is wound around a raw roll, and as shown in FIG. A polishing treatment was performed in the same manner as in Example 1.

Comparative Example 1 The polishing process was performed in the same manner as in Example 1 except that the use of nonwoven fabric was omitted in the polishing process using the polishing device 8 in Example 1.

Comparative Example 2 In the polishing process in the polishing device 8 in Example 1, the use of nonwoven fabric was omitted, and the tension of the magnetic tape was reduced to 1000 gf/
The polishing process was performed in the same manner as in Example 1 except that the polishing process was made to 1 inch.

The protrusion removal rate, number of dropouts, and skew variation were investigated for the magnetic tapes obtained in each Example and Comparative Example. The protrusion removal rate was determined by examining the percentage of tips of protrusions with a diameter of 20 μm or more that were removed using a polarized light microscope. In addition, the number of dropouts is 2,000 m long pancake obtained by winding the original magnetic recording medium onto the take-up roll 13.
Built into the cassette, Hitachi Ltd. vT VT-80
Recording/playback was performed using 00, and the number of drones and poor sounds of 5 μs or more was examined. Furthermore, the skew fluctuation was measured at 40°C and 80°C using Hitachi's VTR1VT-8000.
It was recorded under conditions of % RH, left to stand sufficiently under conditions of 5° C. and 40% RH, and then played back and measured on a Momota TV.

The table below shows the results.

Table [Effects of the Invention] As is clear from the above table, the magnetic tapes obtained by the present invention (Examples 1 to 4) have a higher protrusion removal rate than the magnetic tapes obtained in Comparative Examples 1 and 2. Therefore, according to the manufacturing method and apparatus of the present invention, a magnetic recording medium with good surface smoothness of the magnetic layer and excellent electromagnetic conversion characteristics can be efficiently obtained. I can see it being done.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of the main parts of an example of a polishing device for magnetic recording media of the present invention, and FIG. 2 shows a manufacturing process in which the polishing device for magnetic recording media of the present invention is attached to a cutting device. FIG. 3 is an explanatory diagram schematically showing another example of the magnetic layer polishing process of the present invention. 1... Polishing wheel, 2... Magnetic recording medium, 3...
・Base film, 4... Magnetic layer, 5... Strip-like material, 6
... Spring plate, 8 ... Polishing device, 10 ... Cutting device, 21 ... Magnetic recording medium material, 22 ... Magnetic tape patent applicant Hitachi Maxell, Ltd.

Claims (1)

[Claims] 1. After applying a magnetic paint onto the base film and then smoothing the magnetic layer formed by this application, the surface of the smoothed magnetic layer is 2. A method for manufacturing a magnetic recording medium, characterized in that polishing is carried out by running a polishing wheel made of a high-hardness abrasive material while pressing it with a pressing means. 3. A method for producing a magnetic recording medium according to claim 1, wherein the magnetic recording medium is polished by winding the wheel at a winding angle of 30 to 300 degrees. 4. A method for producing a magnetic recording medium according to claim 1 or 2, wherein the magnetic recording medium is polished by rotating it in a reverse direction with respect to the traveling direction of the formed magnetic recording medium. 5. A method for producing a magnetic recording medium according to claim 3, wherein the magnetic recording medium on which the magnetic layer is formed is polished by rotating at a circumferential speed of 700 m/min and traveling at a running speed of 20 to 500 m/min. 6. The method for producing a magnetic recording medium according to claim 1, wherein the surface is formed of abrasive grains having a Mohs hardness of 9 or more and a grain size of #1500 to #4000. A method 7 for producing a magnetic recording medium according to claim 5, wherein the peripheral surface of the polishing wheel is formed of a ceramic having a Mohs hardness of 9 or more and a grain size of #1500 to #4000. Method 8, the pressing means for pressing the surface of the magnetic layer against the polishing wheel,
9. The method for manufacturing a magnetic recording medium according to claim 9, wherein the magnetic recording medium is a band-shaped object pressed with a tension of 50 to 1000 gf/1 inch width. Method 10: A method for producing a magnetic recording medium according to claim 8, wherein the strip is a nonwoven fabric; 11: A method for producing a magnetic recording medium according to claims 8 to 10, wherein the strip is further pressed with a leaf spring; 13. A method for producing a magnetic recording medium according to claim 11, wherein the magnetic recording medium is pressed with a pressing force of ~100 gf/1 inch width. After processing, the surface of the magnetic layer is cut into a predetermined width, and at the same time, the surface of the multi-layered magnetic layer, which has been smoothed and cut, is run while being pressed by a pressing means against a polishing wheel whose circumferential surface is made of an abrasive material with high hardness. 14. A method for manufacturing a magnetic recording medium characterized by polishing the magnetic layer by pressing the magnetic layer against the polishing wheel by a pressing means,
15. A method for producing a magnetic recording medium according to claim 13, wherein the magnetic recording medium is polished by winding the polishing wheel at a winding angle of 30 to 300 degrees. 16. A method for producing a magnetic recording medium according to claim 13 or 14, wherein the polishing wheel is polished by rotating the magnetic recording medium in the opposite direction to the running direction of the magnetic recording medium having a 17. A method for manufacturing a magnetic recording medium according to claim 15, wherein the polishing wheel is rotated at a circumferential speed of ~700 m/min, and the magnetic recording medium on which the magnetic layer is formed is run at a running speed of 20 ~ 500 m/min for polishing. Claim 1: The peripheral surface is formed of abrasive grains with a Mohs hardness of 9 or more and a grain size of #1500 to #4000.
18. A method for manufacturing a magnetic recording medium according to claim 18, wherein the abrasive grains forming the peripheral surface of the polishing wheel are diamond. 19. A method for manufacturing a magnetic recording medium according to claim 17, wherein the peripheral surface of the polishing wheel has a Mohs hardness. 9 or more, and the method for manufacturing a magnetic recording medium according to claims 13 to 16, wherein the magnetic recording medium is formed of ceramic with a grain size of #1500 to #4000, and the pressing means for pressing the surface of the magnetic layer against the polishing wheel has a width of 50 to 1000 gf/1 inch. 21. The method for producing a magnetic recording medium according to claim 13 to 19, wherein the strip is pressed with a tension of A method 23 for producing a magnetic recording medium according to claim 20, wherein the strip is further pressed with a plate spring. 25. A method for manufacturing a magnetic recording medium according to claim 23, wherein the smoothed magnetic layer of the magnetic recording medium is pressed by a pressing force to a polishing wheel whose circumferential surface is made of an abrasive material with high hardness. 26. The magnetic recording medium manufacturing apparatus according to claim 25, wherein the magnetic recording medium manufacturing apparatus 26 is equipped with a polishing device that performs polishing while being pressed and moved, and the polishing device is attached to a magnetic recording medium cutting device. 27. A device 28 for producing a magnetic recording medium according to claim 25 or 26, wherein the magnetic layer pressed onto the polishing wheel by the pressing means is wound around the polishing wheel at a winding angle of 30 to 300 degrees. 28. The magnetic recording medium manufacturing apparatus 29 according to claim 25, wherein the polishing wheel made of a grinding material having a high hardness is rotated in a direction opposite to the running direction of the magnetic recording medium on which a magnetic layer is formed, the peripheral surface having a high hardness. 29. The magnetic material according to claim 28, wherein a polishing wheel made of abrasive material is rotated at a circumferential speed of 0 to 700 m/min, and the magnetic recording medium on which the magnetic layer is formed is run at a running speed of 20 to 500 m/min. Claim 2: In the recording medium manufacturing apparatus 30, the peripheral surface of the polishing wheel is formed of abrasive grains having a Mohs hardness of 9 or more and a grain size of #1500 to #4000.
The magnetic recording medium manufacturing apparatus 31 according to any one of claims 5 to 29, wherein the abrasive grains forming the peripheral surface of the polishing wheel are diamond, and the magnetic recording medium manufacturing apparatus 32 according to claim 30, wherein the peripheral surface of the polishing wheel has a Mohs hardness. 33, wherein the magnetic recording medium manufacturing apparatus 33 is made of ceramic having a grain size of #9 or more and a grain size of #1500 to #4000, wherein the pressing means for pressing the surface of the magnetic layer against the polishing wheel has a width of 50 to 1000 gf/1 inch. The magnetic recording medium manufacturing apparatus 34 according to any one of claims 25 to 32, wherein the magnetic recording medium is a belt-shaped object pressed by applying a tension of An apparatus for producing a magnetic recording medium according to claim 33, wherein the magnetic recording medium is made of a non-woven fabric; an apparatus for producing a magnetic recording medium according to claims 33 to 37, wherein the strip is further pressed by a plate spring; the plate spring has a width of 10 to 100 gf/1 inch 37. The apparatus for manufacturing a magnetic recording medium according to claim 36, wherein the magnetic recording medium is pressed with a pressing force of