JPH04123312A - Master magnetic recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a master magnetic recording device suitable for copying required information at high speed and with high density using a contact magnetic transfer method. Regarding the medium.

(Prior Art) In recent years, the following contact magnetic transfer method has been known as a manufacturing method for video soft tapes, DAT soft tapes, and the like. That is, a master magnetic tape (master medium) and a slave magnetic tape (slave medium) are run in close contact with each other, and in this area where they run in close contact with each other,
For example, this is a contact transfer method in which the magnetization pattern is transferred as is by applying an alternating current bias magnetic field in the vertical direction. However, this contact transfer method is increasingly being used because it enables high-speed transfer.

By the way, in the above-mentioned contact magnetic transfer method, an in-plane oriented metal coated medium with a high coercive force and high magnetic flux density of about 20,000e, which uses needle-shaped ferromagnetic metal powder as the magnetic powder, is used as the master medium, and a slave medium is also used as the master medium. The transfer efficiency is improved by using a vertically oriented coating medium made of hexagonal ferrite magnetic powder as the magnetic powder, and applying an alternating current bias magnetic field perpendicularly to the medium surface to the area where these two media are in close contact with each other. It is also known that it is effective for improving performance (JAS Conference '86 Proceedings A-6).

Therefore, in implementing this method, an excitation section (bias magnetic field excitation section) consisting of a ring-shaped head, and an opposing magnetic pole made of magnetic soft iron called a transfer drum, which is placed facing and separated from this excitation section, are required. A transfer device is generally used, which includes means for causing the master medium and slave medium to run in contact with each other between the excitation section and the opposing magnetic poles.

According to such a transfer device or transfer method, a bias magnetic field is applied to the in-plane oriented master medium in the direction of the hard axis of magnetization, and to the vertically oriented slave medium in the direction of the easy axis of magnetization. Therefore, the master medium is less likely to be demagnetized, while the scrape medium is more easily magnetized, making it possible to obtain a transfer medium with excellent characteristics in the short wavelength region.

At this time, the coercive force of the in-plane oriented master medium is required to be 2.5 to 3 times as large as the coercive force of the slave medium.

(Problem to be Solved by the Invention) However, in general, master media are required to have superior recording and reproducing properties to those of slave media, especially high short wavelength properties in the submicron wavelength region. The coating master medium was not fully satisfactory in terms of short wavelength output characteristics. That is, DAT, 5
When producing soft tapes whose main components are in the submicron wavelength range, such as VHS, 81■ video, or Hi-8mi+ video, the high output characteristics of the master medium cannot sufficiently compensate for the output loss due to spacing during transfer. is the current situation.

The present invention has been made in response to the above-mentioned circumstances, and enables sufficient transfer efficiency of broadband signals by the contact magnetic transfer method.
In particular, the object of the present invention is to provide a master magnetic recording medium with improved short wavelength output characteristics.

[Structure of the Invention] (Means for Solving the Problems) The master magnetic recording medium of the present invention has a magnetic recording medium on a non-magnetic substrate.
It is characterized in that it has a magnetic recording layer formed by applying hexagonal ferrite powder together with a binder component, and that the squareness ratio of this magnetic recording layer in the vertical direction or in-plane direction is -10.60 or more.

In the master magnetic recording medium according to the present invention, as described above, 7-Fe203 is applied inside the magnetic recording layer (as a base) having a squareness ratio of 0.60 or more in the vertical direction or in-plane direction.
, Co-Deposited 7-Acicular magnetic powder such as Fe2O3 or CrO2 may be applied together with a binder component to provide a magnetic layer oriented in the in-plane direction to form a two-layer structure.

In addition, in the case of a two-layer structure as described above, the in-plane coercive force of the inner magnetic layer should be equal to or lower than the coercive force of the outer (surface side) magnetic recording layer containing hexagonal ferrite powder. It is desirable that the magnitude of the saturation magnetization be equal to or greater than the saturation magnetization of the front side magnetic recording layer.

Further, in the master magnetic recording medium (master medium) having a two-layer structure, (a) the thickness of the inner magnetic layer is increased to increase the elastic deformation rate of the inner magnetic layer;
) The average particle diameter of the hexagonal ferrite powder used in the front side magnetic recording layer is smaller than the average major axis length of the acicular magnetic powder used in the inner magnetic layer, and (C) the penetration of magnetization into the inner magnetic layer is reduced. In order to effectively contribute to the area output, it is desirable that the thickness of the front side magnetic recording layer be 0.3 μm or less.

That is, by making the thickness of the inner magnetic layer thicker than that of the surface magnetic recording layer and making its elastic deformation rate larger than that of the surface magnetic recording layer, the surface roughness of the magnetic recording layer can be reduced. This is because the inner layer, which is thick and has a high rate of elastic deformation, can absorb it, and a medium with good surface properties can be obtained.

In addition, by making the average particle size of the hexagonal ferrite powder that makes up the front side magnetic recording layer smaller than the average particle size (major axis length) of the acicular magnetic powder that makes up the inner magnetic layer, it is possible to This is because the hexagonal ferrite particles constituting the surface layer enter the inner magnetic layer well, and interlayer fusion is performed well, resulting in improved surface properties.

Furthermore, since the maximum output occurs when the magnetization penetrates at a wavelength of about 4 in one layer, by reducing the thickness of the surface side to 0.3 μm or less, the low-frequency output of 1.2 μm or more can be effectively improved. I can do it.

Furthermore, whether the magnetic recording layer has a single-layer structure or a two-layer structure of hexagonal ferrite, the surface roughness of the magnetic recording layer is set to be 0.01 μm or less in terms of center average roughness Ra, and The number of undulating protrusions with a height of 0.03μ or more existing in the running direction in units of 10μ is 10 per 11.
It is preferable not to exceed the number of individuals. By setting the surface roughness of the magnetic recording layer in this way, it is possible to easily suppress an increase in the overall spacing with the slave medium and an increase in transfer loss, so the contact transfer characteristics can be significantly improved. It is from. Note that the vertical squareness ratio in the above is a value obtained by performing demagnetizing field correction of 4πM.

The hexagonal ferrite powder used in the present invention is M type (Magnetoplusbite type).
e) and uniaxially anisotropic hexagonal Ba ferrite, Sr ferrite, in which the W-shaped easy axis of magnetization is perpendicular to the particle plate plane;
Pb ferrite, Ca ferrite, or Ba ferrite in which part of Ba is replaced with S'', Pb, Ca,
Alternatively, ion substituted products of these represented by the following general formula are exemplified.

General formula: M+ O・n((Fe M2)
20311-m s (where Ml is at least one element selected from Ba, Sr, Ca%Pb, M2 is T1, C01Zn-1n
SMnxTISSns ceSV s Nb5SbST
At least one element selected from aSCr, ribs, and V, n is a number from 5.4 to 8.0, ■ is a number from 0 to 0.2, and M2 matches the valence of Fe to be substituted. (The average valence is set to 3 in order to be.

The coercive force of the hexagonal ferrite used in the present invention is preferably 15,000e to 30,000e,
It is desirable that the average particle diameter is 0.03 μm to 0.08 μm layer, and the plate ratio (particle size/thickness) is 3 to 4.

In this way, by satisfying the coercive force, average particle size, plate ratio, and blending ratio with the binder component described below of the hexagonal ferrite powder, the perpendicular squareness ratio or in-plane squareness ratio of the magnetic recording layer can be adjusted. can be controlled to a predetermined value, that is, 0.60 or more.

Binder components used in the master medium of the present invention include polyacrylic resin, vinyl chloride resin, vinyl acetate resin, polystyrene resin, polyurethane resin, polyester resin, polycarbonate resin, epoxy resin, melamine resin, polyamide resin, polybutadiene resin, Examples include resins such as polyacrylonitrile resin, phenol resin, polybutyral resin, phenoxy resin, urea resin, furan resin, and copolymer resins thereof. In order to improve the dispersibility of the hexagonal ferrite powder, resins containing sulfonic acid groups, phosphoric acid groups, carboxyl groups, or alkali metal salt groups or alkaline earth metal salt groups, or amino Resins containing hydrophilic groups such as alkylamino groups, ammonium groups, alkylammonium groups and hydroxyl groups may be added to the aforementioned resins.

Furthermore, it is desirable to add an additive such as a polyamine-based or polyisocyanate-based curing agent to these binder components in order to increase the mechanical strength of the coating layer.

In the present invention, the blending amount of the hexagonal ferrite powder and the binder component is 100% of the hexagonal ferrite powder.
The amount is preferably 20 parts by weight or less, and a range of 5 to 16 parts by weight is particularly suitable.

Further, the magnetic recording layer of the master medium of the present invention may contain an appropriate amount of additives such as a lubricant, a dispersant, an abrasive, or an antistatic agent, if desired.

Here, examples of lubricants include higher fatty acids, fatty acid esters, and silicone-based ones, and examples of dispersants include lecithin, cationic surfactants, anionic surfactants, and nonionic surfactants. can be mentioned. Also, as abrasives, TiO2, Cr203, AJ! 2 (
Examples of the antistatic agent include those having a Mohs hardness of 5 or more, such as SiC, ZrO2, and conductive materials such as carbon black.

The master medium according to the present invention is prepared by thoroughly mixing the hexagonal ferrite powder, the binder component, and optionally the aforementioned additives with a solvent such as toluene, xylene, methyl ethyl ketone, or cyclohexanone, and A hardening agent such as a polyisocyanate compound is added to prepare a magnetic paint, and this magnetic paint is applied onto a non-magnetic substrate made of polyester, polyamide, polyolefin, etc. It can be manufactured by performing inward orientation treatment, drying treatment, smoothing treatment using a calendar, etc. in this order.

Therefore, in such manufacturing processes, for example, by controlling the strength of the vertical alignment magnetic field, coating speed, drying conditions, etc. in the coating process, or by controlling pressure, temperature, speed, etc. in the calendering process, The surface roughness of the magnetic recording layer can be within the above range.

(Function) By setting the squareness ratio of the magnetic recording layer in the perpendicular direction or in-plane direction to 0.60 or more, the master medium of the present invention has the advantage of being superior to conventional ferromagnetic metal coated media as shown below. In comparison, it shows remarkable superiority in the submicron wavelength region, and also sufficiently surpasses the main band of high-density recording systems that are typical of current consumer systems.

That is, as can be seen from Figure 1, which shows the squareness ratio dependence of the output in the submicron region of the hexagonal ferrite coating layer, both the vertical squareness ratio (SQR+) and the in-plane squareness ratio (5QR2) are , 0.60 or more, the larger the value, the greater the output. And conventional metal coated media (M
P), the clearly superior range of 1 dB or more is SQR,
≧0.65.5QR2≧0.70te.

In addition, the stability against the vertical transfer bias magnetic field is
As shown in Figure 2, both SQRl and SQR2 are 0.5
The higher the value is 5 or more, the better it is, SQR+≧0.70
, SQR2≧0.60, it can be seen that almost no output attenuation occurs.

From the above, it can be seen that a master medium having a hexagonal ferrite magnetic recording layer with both SQR+ and SQR2 of 0.60 or more as at least the front side magnetic recording layer has significantly superior characteristics to conventional metal coating type media. I understand.

In addition, the master medium of the present invention is not demagnetized by an << eas magnetic field applied in the same direction as the easy magnetization direction, due to the stability of the magnetization mode of the magnetic recording layer oriented in the perpendicular direction.

Furthermore, in a master medium with a two-layer structure in which a longitudinally oriented magnetic layer made of acicular magnetic powder is provided inside a magnetic recording layer made of hexagonal ferrite powder, vertical alignment on the surface side in ring head recording is possible. Since the magnetic recording layer is difficult to penetrate, the low-frequency output is improved by supplementing it with an inner surface-oriented magnetic layer, and it can exhibit sufficient performance even in a wideband system.

(Example) Examples of the present invention will be described below.

Example 1 Ba-ferrite powder 100 parts by weight (holding car 20000e, average particle size -0.04 μm, plate ratio -3.5) Polyurethane resin 5 // Vinyl chloride-vinyl acetate copolymer resin 7 // Alumina (average Particle size - 0.3 μl) 3. //stearic acid
2 Methyl ethyl ketone/toluene 180/cyclohexanone 1:1:1 mixed solution After mixing the above materials, the mixture was further dispersed for 2 hours using a sand grinder to prepare a magnetic paint.

Adding the hardening agent Coronate to the magnetic paint prepared above, the product name is
After adding 3 parts by weight of (manufactured by Nippon Polyurethane Co., Ltd.), the mixture was coated onto a polyethylene terephthalate film having a thickness of 10 μm using a reverse coater.

Thereafter, it was vertically aligned in a magnetic field of 8 k Oe, dried, cured for 3 days, and then calendered and slitted in order to form a 3.81 am wide film having a 3 μm thick magnetic recording layer. A vertically oriented master magnetic recording tape was fabricated.

Example 2 A magnetic paint having the same composition as in Example 1 was coated with a thickness of lOμ-
A master in-plane oriented magnetic recording tape was prepared by performing the same treatment as in Example 1, except that the in-plane orientation was performed in a magnetic field of 8 k Oe after coating on the surface of the polyethylene terephthalate film.

Example 3 First, an inner magnetic layer containing acicular magnetic powder was formed as follows (coating thickness: 3 μm).

That is, Co-7-Pe2 03 powder 100 parts by weight (coercive force -8000e, average particle size -0.12 pm, acicular ratio -5) Polyurethane resin 7 Vinyl chloride-vinyl acetate copolymer resin 5 Stearic acid
3 〃Methyl ethyl ketone/toluene
18o〃/cyclohexanone 1:1:1 mixed solution After mixing the above materials, use a sand grinder to further add 2
After time-dispersing and adding 3 parts by weight of the hardening agent Coronate L to the obtained magnetic paint, apply a reverse coater to a thickness of 10 μm.
- was coated on the surface of the polyethylene terephthalate film and dried to form an inner magnetic layer with in-plane orientation.

Next, on the inner magnetic layer formed above, the same magnetic paint as in Example 1 was used and coated under the same conditions (to a coating thickness of 3 μm), vertically aligned in a magnetic field of 8 kOe, and dried. After curing for 3 days, calendar processing,
The slitting process was carried out in order to produce a two-layer coated magnetic recording tape for a master having a width of 3.81 ss.

Example 4 In the case of Example 3, both the inner magnetic layer and the front side magnetic recording layer were oriented in-plane to produce a master two-layer coated magnetic recording tape.

Comparative Example 1 Using a magnetic paint prepared in the same manner as in Example 1,
A master vertically aligned magnetic recording tape having a vertical squareness ratio of 0.55 was prepared by changing the conditions for vertically aligning the coating layer in a magnetic field.

Next, regarding the master magnetic recording tapes of Examples 1 to 4 and Comparative Example 1 and the conventional metal coated magnetic recording tape (Comparative Example 2), the squareness ratio (orientation ratio) of each magnetic recording layer, coercive force He Table 1 shows the results of measuring the saturation magnetization contact, center line surface roughness Ra, and frequency of undulating protrusions (numbers/w).
Shown below. Note that in Table 1, the squareness ratio vertical indicates vertical alignment, and the plane indicates in-plane alignment.

Square ratio 1 vertical 0.75 surface 0.70 Example 3 surface vertical 0.75 internal surface 0.70 4 surface 0.75 internal surface 0.70 ratio 1 vertical 0.55 comparison 2 surface 0.80 Table I He Xs (Oe) (emu Ra Waviness (μm) Frequency 0.006 B 0.005 5 o, ooe e 0.005 0.005 o, ooe In addition, the ring head recording and reproducing output in the wavelength range of 0.4 to 4 μm At the same time, we also measured the self-recording playback output.

Further, contact magnetic transfer was performed under the following conditions, and the transfer output was measured. In other words, each master magnetic recording tape has a DA
T Using mirror master machine (relative speed 3.133 m
/second) A rectangular wave with a wavelength of 0.4 to 4 μm is recorded as a mirror pattern, and the master tape and slave magnetic recording tape are brought into close contact with each other by an air pressure system, and a bias magnetic field is applied so that the transfer output is maximized. After the signal magnetic field was applied and the signal magnetic field was transferred, the transferred and reproduced output of the obtained slave tape was determined using a spectrum analyzer using a DAT deck.

The results of these measurements are shown in FIG. 3 and Table 2, respectively. (Margins below) Table 2 λ-0.6 μm Catalog playback output Transfer a power (dB) (dB) Actual 1 B +2.0 Ex 2
2 +1,5 example 3
B +2.04 2
41.5 ratio 1 0.5
+0.2 comparison 2 0
0 Example [Effects of the Invention] As is clear from the above description, the master magnetic recording medium according to the present invention has a shorter wavelength than a conventional metal-coated medium in which the magnetic recording layer is made of acicular magnetic powder. Excellent output characteristics. Therefore, contact magnetic transfer provides high transfer output and good stability after transfer, making it possible to obtain high-quality copies of video signals, audio signals, digital signals, etc. with good reproducibility. .

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing the squareness ratio dependence of the output of the master magnetic recording medium according to the present invention, and FIG. 2 is a characteristic diagram showing the angle of output attenuation due to the vertical transfer bias magnetic field of the master magnetic recording medium according to the present invention. FIG. 3 is a characteristic diagram showing a comparison of the wavelength characteristics of the ring head recording and reproducing output for a master magnetic recording medium according to the present invention and a master magnetic recording tape of a comparative example. Applicant: Toshiba Corporation

Claims (2)

[Claims] (1) It has a magnetic recording layer formed by coating hexagonal ferrite powder together with a binder component on the surface of a nonmagnetic substrate, and the squareness ratio of this magnetic recording layer in the vertical direction or in-plane direction is 0.60. A master magnetic recording medium characterized by the above. (2) A non-magnetic substrate, a magnetic layer formed by applying acicular magnetic powder together with a binder component in an in-plane orientation onto the surface of the substrate, and a hexagonal ferrite powder applied onto this magnetic layer together with a binder component. 1. A master magnetic recording medium comprising: a magnetic recording layer having a predetermined squareness ratio in the vertical direction or in-plane direction;