JP3044672B2 - Magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic tape, a magnetic sheet, and a magnetic disk.

[0002]

2. Description of the Related Art Generally, a magnetic recording medium such as a magnetic tape is
It is manufactured by applying a magnetic paint composed of a magnetic powder, a binder resin and the like on a support and drying it.

A conventional magnetic recording medium generally has only one magnetic layer (single layer). The present inventors have repeatedly studied a video tape which is a medium having such a single magnetic layer, and as a result, the following has been obtained. I found something like that.

That is, the video tape is irradiated with copper Kα characteristic X-rays (wavelength λ = 1.5405 °) by the X-ray diffraction method, and the diffraction peak position (X-ray intensity peak) obtained by lattice scattering is Bragg. At the angle 2θ, the following has been found. In addition, the transfer characteristics, Lumi-S / N, chroma
The method of measuring the S / N and the sliding noise is described in Examples below.

(1). When 2θ is large (2θ ≧ 62.80
°), excellent transfer characteristics, and Lumi-S / N (LS /
N) is also good.

(2). When 2θ is small, (2θ ≦ 62.70
°), C-S / N (chroma-S / N) is good, but L-
S / N and transfer characteristics are inferior.

(3). When 2θ is within a certain range (2θ
= 62.75 °), transfer characteristics, C / S / N and L / S / N are relatively good. However, the sliding noise was significantly deteriorated.

(4). The single magnetic layer has relatively good running durability.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording medium which has good transfer characteristics and chroma S / N, and has improved running durability.

[0010]

According to the present invention, at least two magnetic layers containing different magnetic powders are provided on a non-magnetic support, and the diffraction peak position obtained by the X-ray diffraction method is 6
2.60 ° ≦ 2θ ≦ 62.80 ° (where 2θ is the Bragg angle), and the half width d of the diffraction spectrum showing the diffraction peak is within the range of 0.460 ° ≦ d ≦ 0.600 °. It relates to a medium.

In the present invention, "the magnetic powders are different from each other" means, for example, in terms of the properties of the magnetic powder, the type and amount of the additive element in the magnetic powder, the water content of the magnetic powder, the coercive force (Hc ), BET value, major axis length of magnetic powder, axial ratio, etc.

The inventor of the present invention has proposed a medium having a single magnetic layer,
In a medium having a plurality of magnetic layers, the diffraction peak position of X-ray diffraction (hereinafter the same) by the above-mentioned copper Kα characteristic X-ray (wavelength λ = 1.5405 °) is at 62.60 ° ≦ 2θ ≦ 62.80 °,
If the half width of the spectrum of the diffraction peak (that is, the spectrum width at an intermediate value between the maximum value of the spectrum and the reference level (minimum value)) d is set to be 0.460 ° ≦ d ≦ 0.600 °, It has been found that transfer characteristics, chroma S / N, lume S / N, sliding noise, and running durability are all improved.

In this case, since the magnetic layer has a plurality of layers, the uppermost layer can be formed as a layer having particularly excellent RF output and high durability. Decrease.

In the above, desirably 2θ = 62.60 °
~ 62.77 °, d = 0.470 ° ~ 0.590 °, more preferably 2θ = 62.62 ° ~ 62.75 °, d = 0.475 ° ~ 0.58
0 °.

In the present invention, the peak position and half width d in the X-ray diffraction method vary depending on various factors such as the Hc value of the magnetic powder, the BET specific surface area, the amount of the magnetic powder in the magnetic layer, and the thickness of the magnetic layer. , But especially Fe ²⁺ / Fe ³⁺
Is highly dependent on the ratio of

Therefore, the composition of the magnetic powder is Fe ²⁺ / Fe
By changing the ratio of ³⁺ , that is, the ratio between FeO and Fe ₂ O ₃ , the above-mentioned diffraction peak position can be controlled.

That is, for example, deposition of Co as a magnetic powder
By selecting the x value of FeOx, the above 2θ and d values can be controlled.

The values of 2θ and d can also be controlled by using different kinds of magnetic powders and selecting their mixing ratio, or by selecting the thickness of each magnetic layer. is there.

In the present invention, the lower layer has an x value of 1.34 to 1.
44, preferably 1.35 to 1.42, particularly preferably x value 1.36 to
It is preferable to use a magnetic powder mainly composed of iron oxide (FeOx) of 1.40, and the upper layer is made of iron oxide (F) having an x value of 1.45 to 1.48.
It is preferable to use magnetic powder mainly composed of eOx).

As shown in FIG. 2, the magnetic recording medium of the present invention comprises a first magnetic layer (lower layer) 2 and a second magnetic layer (top layer) on a non-magnetic support 1 made of polyethylene terephthalate or the like. 4) are laminated in this order.

A back coat layer 3 is provided on the side of the support opposite to the lamination surface. An overcoat layer may be provided on the second magnetic layer. In the example of FIG. 3, the lower layer is further divided into a layer 2a and a layer 2b.

In the magnetic recording medium MT shown in FIGS. 2 and 3, the thickness of the first magnetic layer 2 and the thickness of the magnetic layers 2a + 2b are preferably 1.5 to 4.0 μm.
Is preferably 1.0 μm or less (for example, 0.5 μm).

In such a medium, since the magnetic layer is composed of a plurality of layers, the upper layer of the medium has good recording and reproduction characteristics in a high frequency range such as a video output, and the lower layer has relatively high chroma and audio outputs in a lower layer. Each layer can be formed so as to improve low-frequency recording and reproduction characteristics.

For this purpose, the upper layer (particularly the uppermost layer) is generally used.
It is preferable that the coercive force (Hc) is larger than that of the lower layer, and the upper layer has a smaller thickness (or thickness).

In addition to the case where a clear boundary substantially exists between the respective layers of the magnetic layer, there is a case where there is a boundary region having a certain thickness and a mixture of magnetic powders of both layers. However, these layers are the above or lower layers excluding such a boundary region.

Then, the above-mentioned 2θ and d according to the present invention are obtained.
Can be measured as shown in FIGS.

In FIG. 4, a focusing circle FC (focusing circle)
cle, concentrated circle, and Rowland circle), and consider diffraction by a sample SP having a curved surface that touches this focal circle,
The X-ray IL diverging from the X-ray source LS located on the focal yen is incident on the sample SP through a slit S _1.

The diffracted X-ray DL from the sample is concentrated at a point on a focal yen (here put receiving slit S _2). Here, an arbitrary 2θ is measured by a goniometer.
It is considered that the concentration condition is satisfied by (Bragg-Br
entano concentration method). Counter C for intensity of concentrated X-rays
Measure with

The measurement can be performed, for example, by using “JDX-11RA” manufactured by JEOL Ltd. as an X-ray diffractometer and using CuKα radiation.

As shown in FIG. 5, a sample SP is prepared by vertically setting two video tapes MT having the above-described configuration to an aluminum sample holder 20 with an adhesive tape 21 in the longitudinal direction. The powder sample was set in a glass holder. Each tape is made to face a window 22 provided in the holder 20, and the magnetic layer side of the tape existing in this window is set as the X-ray incidence surface in FIG.

The measurement conditions are, for example, 40 KV,
It is assumed that 150 mA, 2θ = 61.6 ° to 64 °, and the step angle is 0.01 °.

FIG. 1 shows an example of a diffraction spectrum obtained by an X-ray diffraction method for a multilayer tape (a magnetic tape having two magnetic layers) based on the present invention. According to this, a diffraction peak is shown at a position where the Bragg angle 2θ is 62.75 °, and the half value width d is 0.581 °.

The magnetic powder used in the upper layer (4 in FIG. 2) of the magnetic layer was Co-coated FeO _x (where x is close to 1.50 ).
Value (x is about 1.50)) , and Co-coated FeO _{x in} the lower layer (2 in FIG. 2) (where x is a value close to 1.33 (x is about 1.30) .
33)) .

On the other hand, the sample of the single magnetic layer is shown in FIG.
An X-ray diffraction spectrum as shown in FIG. 7 was shown. That is,
FIG. 6 shows an X-ray diffraction spectrum of a single-layer magnetic layer using Co-coated γ-Fe ₂ O ₃ as the magnetic powder. According to this, the diffraction peak position is 2θ = 62.89 °, and The half width d is 0.437 °. This is all outside the scope of the present invention.

FIG. 7 shows that Co-coated Fe is used as the magnetic powder.
The X-ray diffraction spectrum of the single-layer magnetic layer using ₃ O ₄ is shown. The diffraction peak position is 2θ = 62.56 °, the half width d = 0.45.
8 °, both of which are outside the scope of the present invention.

The measurement conditions in the above two measurement examples are as follows. Target Cu Step angle 0.010 ° Counting time 2.0sec Tube voltage 40.0KV Tube current 150.0mA

In each of the above X-ray diffraction spectrum measurements, a silicon element was measured as a sample reference. The diffraction peak position of the silicon element is shown in FIG.
Is in the range of 2θ = 69.12 ° to 69.14 ° as shown in
Confirmation was made before and after the measurement of the spectrum. The measurement conditions at this time are the same as the above conditions except that the step angle is 0.002 ° and the counting time is 0.5 sec.

According to the above diffraction spectrum, the peak position of the single-layer magnetic layer in which the magnetic powder is γ-Fe ₂ O ₃ or Fe ₃ O ₄ is larger than the range of the present invention (the γ-Fe ₂ O ₃ Case) or small (in the case of Fe ₃ O ₄ ), the multilayer magnetic layer of the present invention (the upper layer is γ-Fe ₂ O ₃ , and the lower layer is Fe ₃ O ₄ )
It can be seen that the peak position is halfway between the two.
It can also be seen that the half width d of the peak position also changes in the multilayer magnetic layer of the present invention, and rather increases.

The magnetic recording medium of the present invention is, for example, shown in FIGS.
The magnetic layers 2, 2a, 2b, and 4 may contain magnetic powder. As such magnetic powder,
X is 1.33 to 1.50 FeOx, Co-containing or coated γ-Fe
There are iron oxide magnetic powders such as Ox.

From these magnetic powders, those suitable for the magnetic layers 2, 2a, 2b, and 4 can be selected. For example, when a material having a higher coercive force (Hc) than that of the lower layer 2 is used as the upper layer 4, a medium with higher output can be obtained, and the peak position and the half width by the X-ray diffraction are within the range of the present invention. be able to.

Each magnetic layer also contains a lubricant (eg, silicone oil, graphite, molybdenum disulfide, tungsten disulfide, a monobasic fatty acid having 12 to 20 carbon atoms (eg, stearic acid), and a total of 13 carbon atoms. ~ 40 fatty acid esters, etc.), a dispersant (e.g., lecithin), an abrasive (e.g., fused alumina), an antistatic agent (e.g., carbon black), and the like.

The binder usable in the magnetic layer preferably has an average molecular weight of about 10,000 to 200,000. For example, a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-vinylidene chloride copolymer, a vinyl chloride Acrylonitrile copolymer, polyvinyl chloride, urethane resin, butadiene
Acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymer, polyester resin, various synthetic rubbers System, phenolic resin, epoxy resin, urea resin, melamine resin, phenoxy resin,
Examples include silicone resins, acrylic-based reactive resins, mixtures of high-molecular-weight polyester resins and isocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea-formaldehyde resins, mixtures of low-molecular-weight glycols / high-molecular-weight diols / isocyanates, and mixtures thereof. Is done.

These binders are -SO ₃ M, -COO
_{M, -PO (OM ') 2} ( where, M and M' is hydrogen or lithium, potassium, alkali metal such as sodium)
It is preferable to use a resin containing a hydrophilic polar group such as That is, such a resin improves the compatibility with the magnetic powder due to the polar group in the molecule, thereby further improving the dispersibility of the magnetic powder, and also preventing the aggregation of the magnetic powder to further improve the coating liquid stability. Therefore, the durability of the medium can be improved.

Such a binder, in particular, a vinyl chloride copolymer is obtained by copolymerizing a vinyl chloride monomer, a copolymerizable monomer containing an alkali salt of sulfonic acid or phosphoric acid and, if necessary, other copolymerizable monomers. Obtainable. Since this copolymer is obtained by vinyl synthesis, it can be easily synthesized, and various copolymer components can be selected, so that the properties of the copolymer can be adjusted optimally.

The metal of the salt such as sulfonic acid or phosphoric acid is an alkali metal (particularly sodium, potassium, lithium).

In the back coat layer 3, carbon black and, in some cases, non-magnetic particles such as barium sulfate are added to the above-mentioned binder and applied to the back surface of the support.

As the material of the support 1, plastics such as polyethylene terephthalate and polypropylene, metals such as Al and Zn, glass, BN, Si carbide, ceramics such as porcelain and earthenware are used.

Next, FIG. 9 shows an example of an apparatus for manufacturing the above medium.

In this production apparatus, in producing the medium shown in FIG. 2, first, the film-like support 1 pulled out from the supply roll 3 is coated with the respective coating materials for the magnetic layers 2 and 4 by extrusion coaters 10 and 11. After applying, for example, 2000Ga
uss, which is oriented by the pre-orientation magnet 33, and further, for example, 20
00Gauss is introduced into a dryer 34 provided with a post-staged magnet 35, where it is dried by blowing hot air from nozzles arranged above and below.

Next, the dried support 1 with each coating layer
Is guided to a super calendering device 37 composed of a combination of calender rolls 38, where it is calendered, and then wound up by a take-up roll 39.

Each paint may be supplied to extrusion coaters 10 and 11 through an in-line mixer (not shown). Note that, in the figure, the arrow D indicates the transport direction of the non-magnetic base film.

Extrusion coaters 10 and 11 are provided with liquid reservoirs 13 and 14, respectively.
Stack on-wet. To manufacture the medium of FIG. 3, one more extruder coater may be added in FIG.

FIGS. 10 to 12 show examples of an extrusion coater. FIG. 10 is the same as that shown in FIG. 9 (two heads for sequential wet multilayer coating), FIG. 11 is one head (sequential wet multilayer coating), and FIG. ,
4 'is overlapped and ejected in the cross direction inside the head (for simultaneous wet multilayer coating).

Since the above method is a wet-on-wet coating method, the upper layer can be easily coated on the lower layer, and particularly the uppermost layer having a small thickness can be uniformly coated, and a plurality of layers can be coated with good reproducibility. .

The apparatus used for the above-mentioned multi-layer coating is not necessarily an extrusion coater, and other known coating apparatuses can be used.

[0056]

Hereinafter, examples of the present invention will be described together with comparative examples. The components, ratios, operation orders, and the like shown below can be variously changed without departing from the spirit of the present invention. In addition,
In the following examples, "parts" are all parts by weight.

Comparative Examples 1 to 5 Single-layer video tapes were prepared as follows.

<Magnetic paint> Co-coated FeOx (Hc, BET value and x are described in Table 1 below) 100 parts Sulfonate metal salt-modified vinyl chloride-vinyl acetate-vinyl 15 parts Alcohol copolymer (Nihon Zeon) MR110 manufactured by Co., Ltd.) 5 parts of potassium sulfonate-modified polyurethane resin (UR-8300 manufactured by Toyobo Co., Ltd.) Carbon black (particle size: 40 μm) 10 parts α-Al ₂ O ₃ (particle size: 0.2 μm) 3 parts Myristin Acid 1 part Stearic acid 1 part Butyl stearate 1 part Cyclohexanone 100 parts Methyl ethyl ketone 100 parts Toluene 100 parts

After kneading and dispersing the above composition, add 5 parts of Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.
It was applied on a 14 μm polyethylene terephthalate support so as to have a dry film thickness of 4 μm.

Examples 1 to 7 and Comparative Examples 6 to 9 Multilayer videotapes were prepared as follows.

<Magnetic paint for first magnetic layer (lower layer)> Co-coated FeOx (Hc, BET value and x are described in Table 2 below) 100 parts Vinyl chloride-vinyl acetate-vinyl 6 modified with metal sulfonic acid salt Part Alcohol copolymer (MR110 manufactured by Zeon Corporation) Potassium sulfonate-modified polyurethane 11 parts (UR-8300 manufactured by Toyobo Co., Ltd.) Carbon black (particle size 20 mμ) 7 parts Stearic acid 1 part Oleic acid 1 part Butyl stearate 1 part Cyclohexanone 100 parts Methyl ethyl ketone 100 parts Toluene 100 parts

<Magnetic paint for second magnetic layer (upper layer)> Co-coated FeOx (Hc, BET value and x are described in Table 2 below) 100 parts Vinyl chloride-vinyl acetate-vinyl modified with sulfonic acid metal salt 8 Part Alcohol copolymer (MR110 manufactured by Zeon Corporation) Potassium sulfonate-modified polyurethane 6 parts (UR-8300 manufactured by Toyobo Co., Ltd.) α-Al ₂ O ₃ (particle size 0.2 μm) 3 parts Carbon black ( 0.5 part Myristic acid 1 part Stearic acid 1 part Butyl stearate 1 part Cyclohexanone 100 parts Methyl ethyl ketone 100 parts Toluene 100 parts

The first and second magnetic paints are kneaded,
After dispersion, Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.
(Polyisocyanate compound) 5.0 parts each, and wet-on-wet multi-layer coating on a 14.3 μm thick polyethylene terephthalate support so that the dry film thickness becomes 3.0 μm for the first magnetic layer and 0.5 μm for the second magnetic layer Painted by the method, 1 /
A 2 inch video tape was manufactured.

A coating for a BC (back coat) layer having the following composition was applied to the opposite side of the magnetic layer or the like so as to have a dry thickness of 1.0 μm.

Carbon black (R-1035: manufactured by Columbia Carbon Co.) 60 parts Nitrocellulose 30 parts Potassium sulfonate-containing polyurethane resin (UR-8300, manufactured by Toyobo Co., Ltd.) 20 parts Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) 13 parts Cyclohexanone 800 Parts Methyl ethyl ketone 1000 parts Toluene 800 parts

Then, for each of the above tapes, an X-ray diffraction spectrum (CuK
α rays (wavelength 1.5405 °) were measured. The positions of the diffraction peaks and their half-widths d are shown in Tables 1 and 2 below, and the performance of each tape measured as described below is also shown.

(A) Transfer Characteristics Item “7” of the JVC VHS video cassette system standard
(1) One tape T ₁ on which a 1KHz sine wave signal 10 dB larger than the specified recording level is recorded with the reference recording bias current.
When tightly wound ten tape T ₂ which is not recorded alternately as shown in FIG. 13 on the reel spindle R.

(2) Let stand at 30 ° C. and a relative humidity of 65 ± 5% for 24 hours.

(3) The difference between the reproduction level of the recorded portion T ₁ and the output level of the transferred portion T ₂ is measured (unit: dB).

(B) CS / N (Chroma-S / N) Color video noise meter (shibasoku 925 D / 1)
The value was expressed as a value (dB) with respect to a reference tape on a deck of "HR-S7000" manufactured by Victor Company of Japan, Ltd. (signal frequency was 629 KHz).

(C) L / S / N (Lumi / S / N) Measurement was performed using the above-mentioned noise meter (925 D / 1) manufactured by Shibasoku (signal frequency was 6 MHz). The high-pass filter was operated at 4.2 MHz, and the low-pass filter was operated at 10 KHz. The VTR used was JVCHR-D120.

(D) Running durability (reduced RF output) The tape was repeatedly recorded and reproduced 50 times and 100 times at normal temperature and normal humidity.
The output difference between the first RF output and the RF outputs after 50 and 100 times is displayed in dB. The RF output was measured at 6 MHz with the above color video noise meter.

(E) Sliding noise (i) Reproduction is performed without running the tape, and system noise is measured with a spectrum analyzer. (Ii) Reproduce the sample tape 10 times for 1 minute, and measure the sliding noise with a spectrum analyzer. (Iii) System noise is used as a reference for nozzle levels around 8 MHz (0d
As B), the value of the noise of 10 passes is read as an average value. The measurement conditions were 25 ° C. and 10% RH.

[0074]

[0075] * -1 In Comparative Example 5, the magnetic powder of Comparative Example 2 and the magnetic powder of Comparative Example 3 were mixed and used at a ratio of 4: 6 as the magnetic powder. "Ratio-" represents "Comparative Example".

From the results shown in Table 1, the following is clear for the single-layer magnetic layer tape.

(1) If 2θ is large, (2θ ≧ 62.80)
°), excellent transfer characteristics, and Lumi-S / N (LS /
N) is also good.

(2) If 2θ is small, (2θ ≦ 62.70)
°), C-S / N (chroma-S / N) is good, but L-
S / N and transfer characteristics are inferior.

(3) When 2θ is within a certain range (2θ =
62.75 °), transfer characteristics, C / S / N and L / S / N are relatively good. However, the sliding noise was significantly deteriorated.

(4) The single magnetic layer has relatively good running durability.

[0081]

[0082]

[0083]

From the results shown in Table 2, when the 2θ is within the range of 62.60 ° to 62.80 ° of the present invention, the characteristics are good in the case of a multilayer, unlike the single-layer magnetic layer. It can be seen that the dynamic noise is inferior, and when 2θ is too high, the running durability and the sliding noise decrease. Comparative Examples 8 and 9
Then, the performance was very poor probably because the value of d was too low.

Examples 8 to 14 and Comparative Examples 10 to 12 Then, the value of the half width d was examined next.
7, the thickness of the upper and lower layers of the magnetic layer was changed as shown in Table 3 below, and the results shown in the table were obtained.

[0086]

[0087]

From the results shown in Table 3, if the value of d is too small, the transfer characteristics, running durability, and especially the sliding noise are poor. On the other hand, when d was too large, the running durability was particularly deteriorated. The thickness of the magnetic layer affects d, and particularly, the thickness of the upper layer is 0.1 to 1.
The thickness is preferably 0 μm, and the thickness of the lower layer is preferably 1.0 μm or more.

Examples 15 to 16 and Comparative Examples 13 to 16 Next, the magnetic powders used in Comparative Examples 3 and 4 were mixed, and a multilayer tape was prepared in the same manner as in Example 1. The results are shown in Table 4 below, and it can be seen that the value of d also greatly affects the characteristics.

[0090]

[0091]

Examples 17-18, Comparative Examples 17-18 In addition, when the above-mentioned magnetic layer was formed of three layers as shown in Table 5 below (the uppermost layer was 0.3 μm, the intermediate layer 0.7 μm).
m, lower layer 2.4 μm), according to the invention, upper layer, middle layer,
It was also found that by setting the lower layer and setting 2θ and d, the characteristics were good as shown in Table 5 below.

[0093] "Real" indicates an example, and "ratio" indicates a comparative example. (The same applies hereinafter).

[0094]

[0095] * "Actual" indicates an example, and "Ratio" indicates a comparative example.

[0096]

As described above, according to the present invention, the magnetic layer has a plurality of layers and the X-ray peak position is 62.60 ° ≦ 2θ ≦ 62.80.
°, and the half width d is 0.460 ° ≦ d ≦ 0.600 °, so that the transfer characteristics, CS / N, LS / N, running durability and sliding noise are all improved.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction spectrum of a multilayer tape.

FIG. 2 is a sectional view of an example of a magnetic recording medium.

FIG. 3 is a sectional view of another example of the magnetic recording medium.

FIG. 4 is a principle diagram of an X-ray diffraction method.

FIG. 5 is a perspective view of a sample.

FIG. 6 is an X-ray diffraction spectrum of a single-layer tape.

FIG. 7 is an X-ray diffraction spectrum of another single-layer tape.

FIG. 8 is an X-ray diffraction spectrum diagram of a reference sample.

FIG. 9 is a schematic view of an apparatus for manufacturing a magnetic recording medium.

FIG. 10 is a schematic view of an example of an extrusion coater.

FIG. 11 is a schematic view of another example of an extrusion coater.

FIG. 12 is a schematic view of still another example of an extrusion coater.

FIG. 13 is a schematic diagram illustrating a method for measuring transfer characteristics.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-magnetic support 2, 2a Lower magnetic layer 2b Intermediate magnetic layer 2 ', 4' Magnetic paint 3 Back coat layer 4 Upper magnetic layer 10, 11 Extrusion coater 2θ Bragg angle d Half width MT magnetic tape

Continuation of front page (72) Inventor Yuji Shimizu 1 Konica Co., Ltd., Sakura-cho, Hino-shi, Tokyo (56) References JP-A-2-35622 (JP, A) (58) Fields investigated (Int.Cl) . ^7, DB name) G11B 5/716

Claims (1)

(57) [Claims] A nonmagnetic support is provided with at least two magnetic layers each containing a different magnetic powder, and a diffraction peak position obtained by an X-ray diffraction method is 62.6.
Magnetic recording in which 0 ° ≦ 2θ ≦ 62.80 ° (where 2θ is the Bragg angle) and the half width d of the diffraction spectrum showing the diffraction peak is in the range of 0.460 ° ≦ d ≦ 0.600 °. Medium.