JPH0417123A - Contact transfer system for magnetic recording signal - Google Patents

Abstract

PURPOSE:To improve the transfer efficiency of a broad band signal and to stably hold a transferred broad band signal by forming a lower layer with a magnetic layer being a coating layer of acicular magnetic powder - binder group and forming an upper layer with a magnetic layer being a magnetic layer of hexagonal ferrite magnetic powder - binder group. CONSTITUTION:A two-layer magnetic recording medium in which lower layer 4b is made of a magnetic layer being a coating layer of acicular magnetic powder - binder group and an upper layer 4a is made of a magnetic layer being a magnetic layer of hexagonal ferrite magnetic powder - binder group is used as a slave magnetic recording medium 4. Since the upper layer 4a is made of a magnetic layer having a magnetic easy axis in the perpendicular direction being a bias magnetic field direction, even a weak short wavelength magnetic signal from a master magnetic recording medium 3 is easily and surely transferred. On the other hand, since a magnetic layer having a magnetic easy axis is formed in a planar lengthwise direction is formed as the lower layer 4b, a semi-circular magnetization mode is easily and stably formed over an entire wavelength region from a long to a short wavelength for each signal bit and held therein. Thus, the transfer output with high reliability and sufficient performance is obtained.

Description

Detailed Description of the Invention [Purpose of the Invention (Industrial Field of Application) The present invention relates to analog and digital recording signals recorded on a master magnetic recording medium, such as video signals and audio signals, especially digital audio signals. The present invention relates to a method for contact magnetic transfer of images onto a slave magnetic recording medium.

(Prior Art) As a manufacturing method for video soft tapes and DAT soft tapes, instead of the direct recording transfer method in which recording is performed from a master tape recorder to a slave tape recorder at a constant speed of 1:1, the master A contact transfer method in which a slave magnetic recording medium and a slave magnetic recording medium are run in close contact with each other, and the recording signal is transferred as is by applying, for example, an alternating current bias magnetic field in the perpendicular direction in the area where the slave magnetic recording medium runs in close contact with each other. However, it is becoming more widely used because of its ability to perform high-speed transfer.

Note that this contact transfer method involves applying a required bias magnetic field to the area where the master magnetic recording medium and the slave magnetic recording medium are brought into close contact with each other as described above, and applying a sufficient bias magnetic field to the slave magnetic recording medium. In addition to a method of transferring a signal magnetic field to a magnetic field, a method of transferring a signal magnetic field by applying heat above the Curie point is known.

By the way, the slave magnetic recording medium used in the above magnetic transfer method that performs contact transfer using a bias magnetic field has a high coercive force so that the magnetization of the master magnetic recording medium is not demagnetized by the bias magnetic field during contact transfer. It is necessary to use a coercive force that is approximately 1/2 to 1/3 of the coercive force of the master magnetic recording medium. Furthermore, in the case of DAT, 8 mm VTR, etc., high-density recording is performed with the shortest wavelength recording of 1 μm or less, so recording characteristics in the short wavelength region are important.

For these reasons, perpendicular magnetic recording media using hexagonal ferrite powder are attracting attention as slave magnetic recording media used in magnetic transfer systems, which have excellent recording characteristics in the short wavelength region even though their coercive force is relatively low. ing. This is because the axis of easy magnetization of hexagonal ferrite powder is perpendicular to the plate surface, so in magnetic recording media using this powder, the demagnetizing field at the demagnetization reversal boundary can be almost ignored at short wavelengths. .

However, if a magnetic recording medium using hexagonal ferrite powder is simply used as a slave magnetic recording medium,
It has become clear that the transfer efficiency in contact magnetic transfer is not sufficiently improved.

To solve this problem, a proposal was made to improve the transfer efficiency by increasing the vertical squareness ratio of a magnetic recording medium using hexagonal ferrite powder to 0.7 or more (Japanese Patent Laid-Open No. 63-288124). ) has been done.

In the case of the contact magnetic transfer method, experiments conducted by the present inventors have confirmed that the transfer and reproduction output can be increased by increasing the vertical squareness ratio of the perpendicular magnetic recording medium.

(Problem to be Solved by the Invention) However, as described above, while the transfer efficiency can be improved by increasing the vertical squareness ratio of the slave magnetic recording medium used for contact magnetic transfer, In magnetic recording media on which broadband signals are recorded, problems often arise in the frequency characteristics of the output of the transferred recorded signals. In other words, the slave magnetic recording medium requires a recording signal from the master magnetic recording medium,
It is required to have a function (performance) of reliably transferring over the entire wavelength range.

However, according to experiments conducted by the present inventors, even in the case of a slave magnetic recording medium that uses the hexagonal ferrite powder and has a vertical squareness ratio of 0.7 or more, the transfer characteristics over a wide band of recorded signals are poor. In this respect, there are still practical problems. In particular, the output level in the long wavelength range tends to be low.

The present invention has been made in response to the problems of the prior art, and provides a contact magnetic transfer system that can sufficiently functionally transfer broadband signals using the contact magnetic transfer method and stably hold the transferred broadband signals. The purpose is to provide a magnetic transfer method.

[Structure of the Invention] (Means for Solving the Problem) The contact magnetic transfer method according to the present invention brings a magnetic recording medium for a mask and a magnetic recording medium for a slave into close contact with each other, applies a perpendicular bias magnetic field, and transfers the magnetic recording medium for a master. In a magnetic recording signal contact transfer method for transferring a signal magnetically recorded on a recording medium to a slave magnetic recording medium, the slave magnetic recording medium is a magnetic recording medium whose lower layer is made of a coating layer of acicular magnetic powder and a binder system. The present invention is characterized in that it uses a two-layer magnetic recording medium in which the upper layer is a magnetic layer formed of a hexagonal ferrite magnetic powder-binder coating layer.

In the present invention, the two-layer magnetic recording medium includes a multi-layer magnetic recording medium having at least the two magnetic layers described above and substantially exhibiting the effects of the present invention described below.

(Function) In the contact magnetic transfer method according to the present invention, as a slave magnetic recording medium, the lower layer is formed of a magnetic layer consisting of a coating layer of acicular magnetic powder-binder system, and the upper layer is formed of a hexagonal ferrite magnetic powder. - A two-layer magnetic recording medium formed of a magnetic layer consisting of a binder-based coating layer is used as a slave magnetic recording medium.

However, since the slave magnetic recording medium is formed of a magnetic layer containing hexagonal ferrite magnetic powder having an axis of easy magnetization in the perpendicular direction, which is the direction of the bias magnetic field, as an upper layer, Even weak short-wavelength magnetic signals can be easily and reliably transferred. On the other hand, since a magnetic layer containing acicular magnetic powder having an axis of easy magnetization in the in-plane longitudinal direction is formed as the lower layer,
A semicircular magnetization mode can be easily and stably formed and maintained for each signal bit over the entire range from the long wavelength region to the short wavelength region.

(Example) The present invention will be described in detail below with reference to FIG. FIG. 1 is a side view schematically showing an embodiment of the contact magnetic transfer method for magnetic recording according to the present invention, and the gap length is 20.
A required master magnetic recording medium is connected between an excitation part (bias magnetic field excitation part) 1 consisting of a 0 μm ring head and a rotatable drum-shaped opposing magnetic pole part 2 disposed opposite to this excitation part 1. For example, a metal-coated in-plane orientation master tape 3 and a two-layer slave magnetic recording medium 4 run while being regulated by guide rollers 5 .

That is, the master magnetic recording is performed in the peripheral surface area 6 of the rotating drum 2 facing the excitation part 1 which is disposed on the peripheral surface of the rotating drum constituting the opposing magnetic pole part 2 so as to be able to approach and separate by, for example, air pressure. so that the magnetic recording surface of the medium 3 and the magnetic recording surface of the slave magnetic recording medium 4 run in close contact with each other.
It is controlled by guide rollers 5.

Thus, in the region 6 where the master magnetic recording medium 3 and the slave magnetic recording medium 4 run in close contact with each other, a required AC transfer bias magnetic field is generated between the excitation section 1 and the opposing magnetic pole section 2. By applying an AC transfer bias magnetic field to the master magnetic recording medium 3 and the slave magnetic recording medium 4 that are running in close contact with each other, predetermined information is transferred from the master magnetic recording medium 3 to the slave magnetic recording medium. 4 is magnetically transferred.

In the contact magnetic transfer system according to the present invention, as described above, a two-layer slave magnetic recording medium having the following structure is particularly used as the slave magnetic recording medium. That is, on the support substrate, for example, a film surface, a magnetic layer with a thickness of 1 to 5 μm consisting of a coating layer of acicular magnetic powder-binder system as a lower layer, and a 0.1 μm-thick magnetic layer of hexagonal ferrite magnetic powder-binder system as an upper layer. A two-layer magnetic recording medium is used in which a magnetic layer consisting of a coating layer with a thickness of ~1 .mu.m is integrally formed.

Therefore, as the acicular magnetic powder contained in the magnetic layer forming the lower layer, for example, gamma-iron oxide (γ-Fe2O3
), cobalt-coated gamma-iron oxide (Co-7-Pe20
3), chromium dioxide (CrO2), etc.
It is desirable that the holding power of these is equal to or lower than that of the upper layer.

On the other hand, the hexagonal ferrite magnetic powder contained in the upper magnetic layer is M-type (Magnetoplumb).
ite type) or W-shaped hexagonal Ba ferrite with uniaxial anisotropy in which the easy axis of magnetization is perpendicular to the grain plate plane, S
r ferrite, pb ferrite, Ca ferrite, or a part of Ba in Ba ferrite to other 5rSPbs
Examples include those substituted with Ca or ion-substituted products of these represented by the following general formula.

General formula 2M10・n(FeM2)0 1-m m 2 3 (in the formula, Ml
is at least one selected from Ba, Sr, Ca, and Pb, and M2 is Tj, Co5Zn, lnSMn5
TisSnSGeSV, Nbs5bSTa, C
At least one element selected from r, No, W, etc., n represents a number from 5.4 to 6.0, and ■ represents a number from 0 to 2. However, M2 has an average valence of 3 in order to match the valence of Pe to be substituted.) As shown in the above general formula, a part of Pe, which is a constituent element of hexagonal ferrite, is replaced with various metals. Coercive force can be reduced by substitution.

Further, the coercive force of the hexagonal ferrite is 4000e
It is preferable that it is ~8000e, and the average particle size is 0.0
3μm~0.08μm1 plate ratio (particle size/thickness) is 3~
It is preferable that it is 5. By satisfying the coercive force, average particle size, plate ratio, and ratio of the binder component and magnetic powder described below of these hexagonal ferrite magnetic powders, it is possible to control the vertical squareness ratio to a predetermined value. becomes.

For example, by adjusting the vertical squareness ratio to a range of 0.6 or more, it is possible to improve the transfer efficiency during contact magnetic transfer. Note that the vertical squareness ratio here indicates a value after demagnetizing field correction (4πM correction).

The surface roughness of the magnetic recording layer in the slave magnetic recording medium has a center line average roughness of 0.5 μm and a height of 0.0 μm in the running direction in units of several tens of μm.
．． It is preferable that the number of undulating convex portions of 0.03 μm pp or more does not exceed 10. That is, it is possible to easily prevent an increase in the overall spacing with respect to the master magnetic recording medium or an increase in transfer loss.

The binder components used in the two-layer slave magnetic recording medium include polyacrylic resin, vinyl chloride resin, vinyl acetate resin, polystyrene resin, polyurethane resin, polyester resin, polycarbonate resin,
Examples include resins such as epoxy resin, melamine resin, polyamide resin, polybutadiene resin, polyacrylonitrile resin, phenol resin, polybutyral resin, phenoxy resin, urea resin, furan resin, and copolymer resins thereof. In addition, in order to improve the dispersibility of hexagonal ferrite magnetic powder, these resins have sulfone groups,
Resins containing phosphoric acid groups, carboxyl groups, or alkali metal salt groups or alkaline earth metal salt groups, or hydrophilic groups such as amino groups, alkylamino groups, ammonium groups, alkylammonium groups, and hydroxyl groups. A resin may be added and used.

In addition, the blending ratio of the acicular magnetic powder or hexagonal ferrite magnetic powder to the binder component is preferably 20 parts by weight or less, particularly in the range of 8 to 16 parts by weight, per 100 parts by weight of the magnetic powder. It is.

The magnetic recording medium for a slave according to the present invention is produced by thoroughly mixing the above-mentioned acicular magnetic powder or hexagonal ferrite magnetic powder with a binder component, various additives as needed, and a solvent, and further adding a polyisocyanate compound if necessary. After preparing magnetic paints by adding a curing agent such as , these magnetic paints are applied in a predetermined order onto a non-magnetic substrate made of polyester or polyolefin, and then placed on the magnetic coating 2. Self-processing and drying. It can be obtained by performing processing, smoothing processing using a calendar, etc.

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

Co-gamma-iron oxide powder 100 parts by weight (
Coercive Kerr 6000e, average particle size -0.1 μm), polyurethane resin 6 Vinyl chloride-vinyl acetate copolymer resin 8 Stearic acid
2 〃Methyl ethyl ketone/toluene
180/cyclohexanone l:l:l mixed solution After the above materials were mixed, they were further dispersed for 2 hours using a sand grinder. A hardening agent, Coronate L (
After adding 3 parts by weight of (trade name, manufactured by Nippon Polyurethane Co., Ltd.),
It was coated on a polyethylene terephthalate film with a thickness of 10 μm using a reverse coater.

Next, on the surface of the magnetic layer containing the acicular magnetic powder formed above, a magnetic layer containing hexagonal ferrite magnetic powder was formed as an upper layer by simultaneous coating under the following conditions (coating thickness: 0.5 μl/l).

Ba-ferrite powder 1 (10 parts by weight (holding car 6300e, average particle size - 0.05 μm 1 plate ratio - 3.5) Polyurethane resin 3 // Vinyl chloride-vinyl acetate copolymer resin g // Alumina (
Average particle size - 0.3μIn) 3//Stearic acid 2//Methyl ethyl ketone/Toluene 180〃/Cyclohexanone 1:
1:l mixed solution After the above materials were mixed, they were further dispersed for 2 hours using a sand grinder. After adding 3 parts by weight of a hardening agent (Coronate (trade name, manufactured by Nippon Polyurethane Co., Ltd.) to the magnetic paint obtained, it was coated onto a 10 μm thick polyethylene terephthalate film using a reverse coater. After that, vertical alignment was applied in a magnetic field of 6 kOe, and after drying and curing for 3 days, calendering and slitting were performed to form a 3,81" magnetic recording layer with a thickness of 3 μ".
A slave magnetic recording tape for DAT with a width of mm was produced.

Magnetic recording medium (tape) for slave manufactured (configured) as above
Contact magnetic transfer was performed using the following conditions.

First, a DAT mirror master machine was used on a metal tape with a coercive force of 20,000 e (relative speed of 3.133 m/s).
A master tape is prepared by recording a rectangular wave with a frequency of 130 KHz to 4.7 MHz as a mirror pattern in advance, and this master tape and the slave magnetic recording tape are brought into close contact by an air pressure bonding method to maximize the transfer output. A bias magnetic field was applied to transfer the signal magnetic field. Using the slave tape obtained in this way, we measured the transferred and reproduced output using a DAT deck and a spectrum analyzer. As shown in Figure 2, even weak short-wavelength signals were transferred efficiently and reliably. Moreover, it exhibited stable transfer characteristics even in the long wavelength range.

Note that O dB in FIG. 2 is the master tape output, symbol A indicates the case of the embodiment of the present invention, and symbol B indicates the Ba
- In the case of a single-phase ferrite magnetic layer (comparative example).

The reason for this is that, as schematically shown in FIG. 3, the upper layer 4a of the slave magnetic recording medium 4 is a magnetic layer containing hexagonal ferrite magnetic powder having an axis of easy magnetization in the perpendicular direction, which is the direction of the bias magnetic field. Since the master magnetic recording medium 3 is formed by a magnetic recording medium 3, even a weak magnetic signal from the master magnetic recording medium 3 can be easily and reliably transferred. On the other hand, since the lower layer 4b is formed of a magnetic layer containing acicular magnetic powder having an axis of easy magnetization in the in-plane longitudinal direction, a semicircular magnetization mode 7 is generated for each signal bit.
It is thought that it can be easily and stably formed and maintained over the entire range from the long wavelength region to the short wavelength region.

[Effects of the Invention] As can be seen from the above explanation, according to the contact magnetic transfer method according to the present invention, a functionally sufficient or highly reliable transfer output can be obtained, and the transfer output can be maintained in a stable state even after transfer. This makes it possible to obtain copies of high-quality video signals, audio signals, digital signals, etc. with good reproducibility.

[Brief explanation of the drawing]

FIG. 1 is a side view schematically showing an embodiment of the contact magnetic transfer method according to the present invention, FIG. 2 is a characteristic diagram showing an example of frequency characteristics of transfer output by the contact magnetic transfer method according to the present invention, and FIG.
The figure is a schematic diagram showing a transfer mechanism in a contact magnetic transfer method according to the present invention. 1... Excitation section 2... Opposing magnetic pole section 3... Master magnetic recording medium 4...
Slave magnetic recording medium 4a...Top layer 4b of slave magnetic recording medium...Lower layer 5 of slave magnetic recording medium...Guide roller Applicant: Toshiba Corporation

Claims (1)

[Claims] A master magnetic recording medium and a slave magnetic recording medium are brought into close contact with each other, a perpendicular bias magnetic field is applied, and signals magnetically recorded on the master magnetic recording medium are transferred to the slave magnetic recording medium. In the contact transfer method of magnetic recording signals, the slave magnetic recording medium has a lower layer formed of a magnetic layer consisting of a coating layer of acicular magnetic powder and a binder system, and an upper layer formed of a coating layer of hexagonal ferrite magnetic powder and a binder system. A contact transfer method for magnetic recording signals characterized by using a two-layer magnetic recording medium formed of magnetic layers.