JPH052740A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a sufficient reproduced picture signal and sound signal, even at the time of operating a dubbing in a high speed dubbing system. CONSTITUTION:As for a magnetic recording medium 41, when the relaxation point of an outermost layer magnetic recording layer 12 is defined as deltau, and the relaxation point of at least one layer non-magnetic colored layer 11 is defined as deltad, the following expression; deltau-deltad>0 (provided that deltad>=0 deg.C) is obtained.

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.

[0002]

2. Description of the Related Art In recent years, with the advent of the so-called AV (audio-visual) era, the demand and production volume of packaged visual media have increased, and particularly large amounts of live video, music, movies, anime, theaters, etc. Video products recorded with are being consumed in large quantities every day as commercial products or as rental videos.

A real-time dubbing method is also available as a dubbing method for producing the above-mentioned video products containing music, movies, etc. However, since it is time-consuming and expensive, for example, the HSP (high speed printer) method is currently used. , A high-speed dubbing method such as a TMD (Thermal magnetic duplication) method has begun to be used.

By the way, as one of the problems in performing the dubbing by the above-mentioned method, if the RF output of the blank tape for copying the information on the mother tape is not sufficiently high, a clear image or the like will be obtained. It was difficult to reproduce.

However, the above-mentioned magnetic tape having a sufficiently high RF output is not practical because it is difficult to make and the manufacturing cost is high.

[0006]

An object of the present invention is to provide a magnetic recording medium capable of obtaining a sufficient reproduced image signal and audio signal even when dubbing by a high speed dubbing method is performed.

[0007]

That is, the present invention provides the outermost layer of a magnetic recording medium having one or more magnetic recording layers and one or more nonmagnetic colored layers on a nonmagnetic support. When the relaxation point of the magnetic recording layer is δ _u and the relaxation point of at least one non-magnetic colored layer is δ _d , δ _u −δ _d > 0 (where δ _d ≧ 0 ° C.) The present invention relates to a magnetic recording medium.

It is preferable that δ _u −δ _d is larger than 5.

Further, the present invention is a magnetic recording medium having one or more magnetic recording layers and one or more non-magnetic colored layers on a non-magnetic support, and the relaxation of the outermost magnetic recording layer. point and [delta] _u, when a relaxation point of the non-magnetic colored layer of at least one layer has a [delta] _d, a δ _u -δ _d> 0 (where, δ _d ≧ 0 ℃), and the non-magnetic colored The magnetic recording medium is also characterized in that the layer is colored in a color different from that of the magnetic recording layer.

In the present invention, it is preferable that the non-magnetic colored layer contains at least one of a white pigment, a coloring pigment and a coloring dye.

The present inventor diligently studied a magnetic recording medium capable of obtaining a sufficient reproduced image signal and audio signal even when performing high-speed dubbing, and by adjusting the relaxation point of each layer, magnetic recording was performed. The inventors of the present invention have found that sufficient reproduction of the above signals can be performed without changing the layer structure and have reached the present invention.

Generally, polymer materials possess both properties of elasticity and viscosity, but it is known that the magnitude and ratio of elasticity and viscosity change depending on deformation by load, its deformation speed, temperature, and the like. Has been.

By the way, the dynamic viscoelasticity of a polymer material in the field of rheology is usually measured by examining the stress response when a stimulus of sinusoidal strain is applied to the material.
An outline is performed as follows.

Sinusoidal strain (ε ^* ) as a stimulus on a material
When the stress is added, a stress (σ ^* ) whose phase is advanced by δ with respect to this strain (ε ^* ) is generated. However, by measuring the response (σ ^* ) of this sinusoidal stress, the complex elastic modulus Ε ^* ( iω)
Ask for. [Ε ^* (iω) = σ ^* (t) / ε ^* (t),
i = imaginary unit, ω = 2πf angular frequency, t = time. ]

[0015] The complex modulus of elasticity Ε ^* (iω) is, Ε ^* (i
ω) = Ε '(ω) + i Ε "(ω), Ε" / Ε'
Is equal to tan δ. Here, Ε '(ω): indicates the magnitude of the stress component in phase with the strain generated when a sinusoidal strain having a unit magnitude is applied, and is called "storage elastic modulus". Ε ”(ω): A stress component in which π / 2 phase is advanced from the strain and is called“ loss elastic modulus ”. Ε "/ Ε '= tan δ. This tan δ is called the relaxation point, and is a characteristic peculiar to polymer materials that also resembles the glass transition point.

With respect to the measurement of the relaxation point, the temperature dependence of the elastic modulus can be easily obtained under a constant frequency or several levels of frequency due to the spread of a viscoelasticity measuring device, particularly a forced vibration type direct reading type elastometer. The measurement results are often presented in a temperature-dependent manner. (For the outline of viscoelastic behavior of polymer solids and its measuring method, see, for example, Chemical Society of Japan, New Experimental Chemistry Course, Polymer Chemistry [II], 1978.
It is described in the annual edition, Maruzen Co., Ltd., pp. 679-716. )

The relaxation point of the polymer material can be easily measured by a commercially available dynamic viscoelasticity automatic measuring instrument such as Rheovibron DDV-II-EA (trade name) manufactured by Toyo Baldwin Co., Ltd. You can

The present inventor has studied how the relaxation point δ _u of the magnetic recording layer and the relaxation point δ _d of the non-magnetic colored layer affect the electromagnetic conversion characteristics of the magnetic recording medium. By adjusting δ _u and δ _d within specific ranges, it was possible to form a magnetic recording medium in which the reproduction output remarkably increased without changing the structure of the magnetic recording layer.

Although the reason why the above high performance magnetic recording medium can be obtained is not clear, the above δ _u is made larger than δ _d ,
Further, by setting δ _d ≧ 0, the elasticity of the non-magnetic colored layer becomes smaller than the elasticity of the outermost magnetic layer.
A so-called cushioning effect is generated, and the sliding contact with the mirror / mother / tape is improved during high-speed dubbing, and the transfer characteristics are improved. It is also considered that the reason is that the contact between the magnetic head and the magnetic recording medium during reproduction is smoothly performed without hitting the head or the like.

In the present invention, the ferromagnetic powder used in the magnetic recording layer is γ-Fe ₂ O ₃ , Co-containing γ-F.
e ₂ O ₃ , Co deposition γ-Fe ₂ O ₃ , Fe ₃ O ₄ , Co
Containing Fe ₃ O _4, Co deposited Fe ₃ O _4, Co-containing magnetic F
Examples thereof include oxide magnetic materials such as eOx (3/2>x> 4/3) and CrO ₂ . In addition, hexagonal ferrite such as barium ferrite and iron nitride are also used.

In addition to the above, ferromagnetic metal powders can be used, and examples of this include Fe, Ni, Co, and Fe-
Al-based, Fe-Al-Ca-based, Fe-Al-Ni-based, F
e-Al-Zn system, Fe-Al-Co system, Fe-Ni
System, Fe-Ni-Co system, Fe-Ni-Si-Al-M
n-based, Fe-Ni-Si-Al-Zn-based, Fe-Al-
Si-based, Fe-Ni-Zn-based, Fe-Ni-Mn-based, F
e-Ni-Si system, Fe-Mn-Zn system, Fe-Co-
Examples include Ni—P-based, Co—Ni-based, etc., metal magnetic powders containing Fe, Ni, Co, etc. as the main components, and Cu, Cr, etc. elements or their compounds as additives to these metal magnetic materials. May be included.

A lubricant (for example, silicone oil, graphite, molybdenum disulfide, tungsten disulfide, or the like) may be added to the magnetic recording layer and the non-magnetic colored layer, if necessary.
Monobasic fatty acids having 12 to 20 carbon atoms (eg stearic acid), fatty acid esters having 13 to 40 carbon atoms, etc.),
Abrasives (eg α-Al ₂ O ₃ ), antistatic agents (eg carbon black, graphite), dispersants (powdered lecithin) and the like may be added.

The binder used in the magnetic recording layer and the non-magnetic coloring layer preferably has an average molecular weight of about 10,000 to 200,000, such as vinyl chloride-vinyl acetate copolymer,
Vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, polyvinyl chloride, urethane resin, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (cellulose acetate butyrate, cellulose diacetate, cellulose Triacetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymer, polyester resin, various synthetic rubbers, phenol resin, epoxy resin, urea resin, melamine resin,
Phenoxy resin, silicone resin, acrylic reaction resin,
Examples include mixtures of high molecular weight polyester resins and isocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, low molecular weight glycol / high molecular weight diol / isocyanate mixtures, and mixtures thereof.

These binders are -SO ₃ M, -OS
At least one polar group selected from the group consisting of O ₃ M, —COOM and —PO (OM ′) ₂ (provided that M represents a hydrogen atom or an alkali metal atom such as Na, K, or Li; M'is a hydrogen atom, an alkali metal atom such as Na, K or Li, or an alkyl group.) It is preferable from the viewpoint of dispersibility of the magnetic powder and the like.

The relaxation points δ _u and δ _{d according} to the present invention can be controlled by adjusting the physical properties and blending ratio of the binder. For example, when a mixed system of a vinyl chloride copolymer and a polyurethane resin is used as a binder, it is preferable to use a vinyl chloride copolymer having a Tg of 50 to 80 ° C, more preferably 60 to 75 ° C. Those are preferable. For polyurethane resin, Tg is -10.
It is preferable to use one having a temperature of -60 ° C, and further -5
30 ° C. is preferable.

Regarding the compounding ratio of the binder, the weight ratio of the vinyl chloride copolymer to the polyurethane resin is 0:10 to 10: 0, and more preferably 1: 9 to 9: 1.

In addition to the above-mentioned binder, the non-magnetic colored layer contains white pigments such as alumina and titanium oxide, green pigments such as chromium oxide, yellow pigments such as chrome yellow and titanium oxide, and red pigments such as red iron oxide. It The particle size of these pigments is preferably from 0.1 to 10 μm, more preferably from 0.1 to 2 μm.

In the non-magnetic colored layer, a phthalocyanine dye, an azo dye, an anthraquinone dye, an indigoid dye, a nitro and nitroso dye, a quinoline dye, a methine dye, a thiazole dye, a quinoneimine dye, an azine may be used in place of or in combination with the above pigments. Dyes, oxazine dyes, thiazine dyes, azoic dyes, diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, acridine dyes, oxidation dyes, sulfur dyes, phthalein dyes, aminoketone dyes, oxyketone dyes and the like can be contained.

The content ratio of the pigment or dye in the non-magnetic colored layer is preferably 100 to 10,000 parts by weight, more preferably 300 to 3000 parts by weight, based on 100 parts by weight of the binder. The film thickness is preferably 0.1 to 10 μm, more preferably 0.5 to 6 μm.

The non-magnetic support is transparent and includes polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, polyamides and polycarbonates. Plastic is mentioned as a constituent material.
In addition, metals such as Cu, Al and Zn, glass, boron nitride,
Ceramics such as Si carbide can also be used. The thickness of this support is preferably about 3 to 100 μm, more preferably 5 to 50 μm.

When the non-magnetic colored layer and the magnetic layer are formed on the support, the former layer is coated and dried, and then the latter layer is stacked (so-called wet-on-dry coating system). There is a method of coating the next layer on the layer in a wet state simultaneously or sequentially (so-called wet-on-wet coating method = wet multi-layer coating method), but with a film, it is wet-on in view of surface properties. -It is preferable to perform simultaneous multilayer coating by the wet multilayer coating method. It is preferable to add an isocyanate-based curing agent to the magnetic paint, and it may be better to add such a curing agent to the paint for the non-magnetic colored layer.

FIG. 1 shows an example of a magnetic recording medium formed by using each of the above components. A non-magnetic colored layer 11 and a magnetic recording layer 12 are applied in this order on a transparent non-magnetic support 10 using a wet-on-wet method.

FIG. 3 is a diagram showing an example of measurement of relaxation points of a conventional single layer tape and the multilayer tape according to the present invention. As is clear from this figure, in the single-layer tape, only a single relaxation point P ₁ appears, but in the multi-layer tape of the present invention,
There are multiple relaxation points of P ₁ '(from the outermost layer) and P ₂ (from the lower layer).

As shown in FIG. 3, in the conventional single-layer tape, only one relaxation point appears even if the glass transition point or the blending ratio of the binder is changed. For example, when the relaxation point is higher than 60 ° C. Results in a decrease in output due to poor sliding contact with the head because the elasticity of the tape becomes too strong, and running durability is markedly reduced if the relaxation point is lowered to 20 ° C. That is, in the single-layer tape, the relaxation point can be set only in the range of 50 to 70 ° C.

On the other hand, the present invention has a multi-layer structure having at least one magnetic recording layer and at least one non-magnetic colored layer, and the relaxation point of the non-magnetic colored layer can be freely set. As shown in FIG. 3, the outermost layer imparts high elastic physical properties for running durability, and a non-magnetic colored layer having low elasticity is provided as a lower layer to obtain a magnetic recording medium having good sliding contact with the head. It will be easy.

The relaxation point δ _u of the magnetic recording layer 12 of this magnetic recording medium 41 and the relaxation point δ _d of the non-magnetic colored layer 11 have a relationship of δ _u −δ _d > 0 (where δ _d ≧ 0 ° C.). is there. This δ _u −δ _d is preferably δ _u −δ _d > 5, more preferably δ _u −δ _d > 10. Further, δ _d ≧ 10 ° C. is preferable, and δ _d ≧ 20 ° C. is more preferable.

When the above δ _u −δ _d is 0 or smaller, elasticity becomes too high, the sliding contact state with the magnetic head deteriorates, and the output decreases. Further, when δ _d is less than 0 ° C., sticking to the drum or the like occurs and running durability deteriorates.

Further, when the magnetic recording medium 41 shown in FIG. 1 is a tape, when the tape is viewed from the side 13 of the magnetic recording layer 12, the color of the magnetic recording layer 12 (usually blackish brown) can be seen, but the opposite. When the tape is viewed from the direction 14, the color (for example, white) of the non-magnetic colored layer 11 can be seen through the transparent support 10.

If the non-magnetic colored layer 11 is configured to contain a white pigment and a colored pigment, the color of the magnetic recording layer 12 (usually blackish brown) is blocked by the white pigment when viewed from the direction 14. Since it is weakened, the color of the non-magnetic colored layer 11 can be clearly distinguished from the magnetic recording layer 12 and can be recognized. In this case, the color of the non-magnetic colored layer 11 can be a pastel tone in which white is mixed with the color pigment.

The tape is constructed as described above, and the tape is provided in the form of pancake to an authorized dubler who has the copyright. In this way, when stored in a tape cassette, it is easier to judge whether the tape is a pirated copy or not by comparing whether the color is different between the above directions 13 and 14 as compared with the case where another tape is dubbed on another tape. Can be determined.
In other words, in a pirated version, the colors observed in directions 13 and 14 are the same because there is no non-magnetic colored layer 11.

The tape of FIG. 1 based on the present invention is extremely difficult to manufacture even if a pirated manufacturer manufactures a similar product by processing it into a raw tape. Therefore, imitation is prevented. Moreover, it is possible to color the tape manufacturer's original color by selecting the above-mentioned color.

Particularly, unlike the case body of the tape cassette, the tape itself housed in the cassette body is processed to have a discriminating power, so that the imitator must process the video tape itself. I won't.

In the above-mentioned tape (the same applies to the tape described later), it is preferable that the above-mentioned color difference is within the following range. That is, the color of the tape 41 is changed to the tape surface 13
And from the back 14 color analyzer (CM by Murakami Color Co., Ltd.
S-1200) to measure L ^* , a ^* , b ^* , color difference Δ
Calculate E ^* _ab . (About this, CIE (Commissi
on Internationale de l'Eclairage) Color system recommended in 1976: CIELAB). And this color difference ΔE
Regarding ^* _ab , the difference between the tape back surface 14 side and the tape front surface 13 side {ΔE ^* _ab (rear surface) -ΔE ^* _ab (front surface)} is preferably 5.0 or more, further 10.0 or more and 100.0 or less. .

Further, according to the tape of FIG. 1, since the non-magnetic colored layer 11 is provided separately from the magnetic recording layer 12, the color of the above-mentioned color is compared with the case where a pigment or the like is added to the magnetic recording layer 12. The contrast is good at the time of determination, and the electromagnetic conversion characteristics of the magnetic recording layer 12 are not adversely affected. Moreover, since the non-magnetic colored layer 11 is not exposed on the outer surface, the non-magnetic colored layer 11 does not come off due to the sliding friction with the traveling system. Further, there is an undercoating effect between the magnetic recording layer 12 and the support 10, and the adhesive strength of the magnetic recording layer 12 is improved.

FIG. 2 shows an example of another tape. In this example, compared to the tape of FIG. 1, the non-magnetic colored layer
Two layers 11 are provided, the lower layer 11a is a colored pigment layer, and the upper layer 11b is a white pigment layer. As a result, the color pigment layer 11
The color a is further enhanced by the white pigment layer 11b, the influence of the color of the magnetic recording layer 12 can be sufficiently blocked, and the contrast with the color of the magnetic recording layer 12 is further improved. In the case of FIG. 2, the support itself may be colored without using the colored layer 11a.

In the layers 11a and 11b, the content ratio of each pigment is preferably 400 to 3000 parts by weight per 100 parts by weight of the binder in both layers 11a and 11b. The thickness of each layer is layer 11a,
For both 11b, 0.5 to 4.0 μm is preferable. In addition to the above-mentioned configuration, each layer may be a combination of different pigment layers.

[0047]

Next, specific examples of the tape and tape cassette according to the present invention will be described in more detail.

The components, ratios, operation sequences and the like shown below can be variously modified without departing from the spirit of the present invention. In the following examples, all "parts" are parts by weight.

First, a non-magnetic coloring layer and a magnetic layer were formed on a polyethylene terephthalate base film having a thickness of 14.0 μm as a support by the following procedure.

<Composition of paint for non-magnetic colored layer> Pigment (A) (see Table 1 below) 100 parts Pigment or dye (B) (see Table 1 below) Part B Vinyl chloride system containing sulfonic acid metal salt Resin X part (MR-110 manufactured by Nippon Zeon Co., Ltd.) (Tg≈65 to 70 ° C.) Polyester polyurethane resin containing sulfonic acid metal salt Y part (UR8700 manufactured by Toyobo Co., Ltd.) (Tg≈−5 to 0 ° C.) Cyclohexanone 30 Parts Methyl ethyl ketone 20 parts Toluene 20 parts The above coating components were kneaded and dispersed. Then, using the pigments (A) and (B) as shown in Table-1, colored layers (a) to (d) shown in Table-1 were prepared.

<Composition of Magnetic Coating I> Ferromagnetic powder Co-γ-Fe ₂ O ₃ 100 parts (Hc: 700 Oe, specific surface area = 40 m ² / g) α-Al ₂ O ₃ 5 parts Sulfonic acid metal salt included Vinyl chloride resin 10 parts (MR-110 manufactured by Zeon Corporation) Polyester polyurethane resin containing metal sulfonate 5 parts (Toyobo Co., Ltd. UR8700) Carbon black 1 part Myristic acid 0.5 parts Stearic acid 1.5 parts Butyl stearate 1 part Cyclohexanone 100 parts Methyl ethyl ketone 100 parts Toluene 100 parts The above magnetic paint components were kneaded and dispersed, and then 5 parts of Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd. was added to obtain a magnetic paint.

<Composition of Magnetic Paint II> Ferromagnetic powder in place of the ferromagnetic powder of Magnetic Paint I: Cobalt-modified Fe ₃ O ₄ (H
Magnetic paint II was prepared in the same manner as magnetic paint I, except that c = 700 Oe and specific surface area = 40 m ² / g) were used.

<Composition of Magnetic Paint III> Ferromagnetic plate-like hexagonal ferrite (Hc =
A magnetic paint III was prepared in the same manner as the magnetic paint I except that 1000 Oe and a specific surface area of 55 m ² / g) were used.

<Composition of Magnetic Paint IV> In the same manner as Magnetic Paint I except that ferromagnetic chromium oxide (Hc = 700 Oe, specific surface area = 30 m ² / g) was used in place of the ferromagnetic powder of Magnetic Paint I. , Magnetic paint IV was prepared.

A sample having a width of 1/2 inch was obtained by applying each of the above-mentioned coating materials in a layer structure as shown in Table 2 below on a support having a thickness of 14.0 μm by a wet-on-wet method. I made a tape. In the table, "actual" is an example,
“Ratio” indicates a comparative example (hereinafter the same). The results of performance evaluation of each example are shown in Table-3.

[0056]

[0057]

[0058]

(A). RF-output (1): Color video noise meter "Shibasoku 925 D / 1" was used, and the value was shown with respect to the reference tape on the "HR-S 700" deck manufactured by Victor Company of Japan.

(B). RF-output (2): The above RF output (1) of what was recorded by a high-speed sprinter (SONY Magnescale Model HSP5000R) (however, * was recorded by using Otani Electric T-700 TMD). It measured similarly.

(C). Envelope measurement: Using a deck in which the tension of the running system was lowered, the envelope waveform of the RF output in the EP mode (long time mode) of each tape was observed with an oscilloscope, and one of the waveform width was measured. The ratio of the widest part and the narrowest part is shown in%.

(D). Running durability 400 pa of tape at normal temperature and humidity (20 ° C, 25% RH)
When running ss, ○: 400 pass, running without problems. B: Running failure occurs during 350 to 400 pass. ×: Running failure or stop during 100 to 200 passes. XX: Poor running or stopping during 0 to 100 passes.

(E). Relaxation point measurement: Rheovibron DDV-II-EA manufactured by Toyo Baldwin Co., Ltd. was used to measure the relaxation point of each tape at a measurement temperature range of -50 to 100 ° C, a heating rate of 2 ° C and a frequency of 11 Hz. Measure.

Next, for each tape obtained above,
The color of the tape was measured from the front side and the back side with a color analyzer (CMS-1200 manufactured by Murakami Color Co., Ltd.), and L ^* , a ^* , b ^* were measured ^.
And the color difference ΔE ^* _ab was calculated (for this, CI
E (Commission Internationale de l'Eclairage) 1976
Color system recommended by year: CIELAB). The results are shown in Table 4 below.

[0065]

[0066]

From the above results, since the magnetic tape according to the present invention can set a plurality of relaxation points due to the multilayer structure, the mirror mother tape at the time of high-speed dubbing without lowering the running durability and the like. And the RF output (2) is high, and as is clear from the result of the envelope measurement, the RF output (1) is also high because the sliding contact with the head is good. Therefore, it is possible to obtain a magnetic tape capable of obtaining a sufficient reproduced image signal and audio signal even when dubbing by the high-speed dubbing method is performed.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of a magnetic tape according to the present invention.

FIG. 2 is a sectional view of another example of the magnetic tape according to the present invention.

FIG. 3 is a diagram showing examples of relaxation points of single-layer and multi-layer tapes.

[Explanation of symbols]

10 Non-magnetic support 11 Non-magnetic colored layer 12 Magnetic recording layer 13 direction (from front side) 14 (from the back) direction 41 magnetic tape

Claims (4)

[Claims] 1. In a magnetic recording medium having one or more magnetic recording layers and one or more non-magnetic colored layers on a non-magnetic support, the relaxation point of the outermost magnetic recording layer is δ _u. And the relaxation point of at least one of the non-magnetic colored layers is δ _d
The magnetic recording medium is characterized in that δ _u −δ _d > 0 (where δ _d ≧ 0 ° C.). 2. The magnetic recording medium according to claim 1, wherein the δ _u and δ _d satisfy the following equation: δ _u −δ _d > 5. 3. In a magnetic recording medium having one or more magnetic recording layers and one or more non-magnetic colored layers on a non-magnetic support, the relaxation point of the outermost magnetic recording layer is δ _u. And the relaxation point of at least one of the non-magnetic colored layers is δ _d
Then, δ _u −δ _d > 0 (where δ _d ≧ 0 ° C.), and the non-magnetic colored layer is colored in a color different from that of the magnetic recording layer. recoding media. 4. The magnetic recording medium according to claim 1, wherein the non-magnetic coloring layer contains at least one of a white pigment, a coloring pigment and a coloring dye.