JPH0441454Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Field of Application] The present invention relates to a magnetic recording medium having a magnetic recording layer formed by oblique deposition, which has an excellent external shape and excellent magnetic properties such as coercive force. [Prior Art] In order to increase the density of magnetic recording, there are increasing demands for higher coercive force and higher magnetic flux density of magnetic recording media, as well as thinner magnetic recording layers. A magnetic recording medium obtained by obliquely depositing a ferromagnetic metal onto a substrate is known as
Furthermore, a method has been proposed in which a non-magnetic metal layer is provided on a substrate to a thickness of about 50 to 1000 Å, and a magnetic recording layer is provided on the non-magnetic metal layer. [Problem to be solved by the invention] In magnetic recording media obtained by oblique deposition as described above, increasing the residual magnetic flux for the purpose of increasing output and decreasing distortion increases the thickness of the magnetic recording layer. However, when performing oblique evaporation using a cobalt-based alloy, simply increasing the thickness of the magnetic recording layer will cause a decrease in magnetic flux density, a change in the direction of easy magnetization, and a change in the crystal state due to changes in the crystal state.
In addition to a decrease in squareness ratio and the generation of Blochow domain walls, this is undesirable because it causes a decrease in coercive force. Furthermore, if the thickness of the magnetic recording layer is increased, the flexibility will be impaired if the substrate is flexible, and if a thermoflexible synthetic resin substrate is used, curling will occur. In addition, in the method of forming a non-magnetic metal layer with a thickness of about 50 to 1000 Å on the substrate and then forming a magnetic recording layer on top of it, the residual magnetic flux can be increased, but the degree of oxidation on the surface of the non-magnetic metal can be increased. The graininess causes a change in the crystalline state of the upper magnetic recording layer, which in many cases has the disadvantage of reducing the coercive force. Furthermore, when a flexible substrate is used, it is difficult to expect much effect in eliminating curls. In addition, there is a problem of corrosion because the metal layers of different types are in contact with each other, and corrosion tends to progress in humidity, sweat, and in some cases, rainwater or seawater as they constitute a local battery. In contrast, the present invention provides a magnetic recording medium that not only increases residual magnetic flux but also prevents curling of the medium and improves corrosion resistance. [Means for Solving the Problems] The magnetic recording medium of the present invention has a magnetic recording layer made of an alloy of cobalt and nickel formed by oblique evaporation on a substrate, and a polyvinyl chloride-based material containing carboxyl groups. The main idea is a magnetic recording body characterized by sequentially laminating an intermediate layer made of a copolymer resin and a magnetic recording layer made of an alloy of cobalt and nickel formed by oblique evaporation. . Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing the structure of the magnetic recording medium of the present invention, in which a first magnetic recording layer 2 (mainly made of cobalt and alloyed with nickel) is formed on the surface of a substrate 1 by oblique evaporation. (hereinafter simply referred to as a magnetic recording layer 2), an intermediate layer (hereinafter simply referred to as an intermediate layer) 3 made of a polyvinyl chloride copolymer resin containing carboxyl groups, and a second cobalt layer formed by oblique evaporation. Magnetic recording layers 4 (hereinafter simply referred to as magnetic recording layers 4) made of an alloy with nickel are sequentially laminated. In the above, the substrate 1 may be a heat-resistant synthetic resin film such as polyethylene terephthalate film, polyimide film or polycarbonate film, metal foil such as aluminum foil, non-magnetic nickel foil, copper foil or stainless steel foil, or glass or ceramic. Can be used. Among these, when manufacturing a magnetic recording medium in the form of a magnetic tape, it is preferable to use a polyethylene terephthalate film having a thickness of 4 μm to 25 μm in terms of heat resistance, tensile strength, and dimensional stability. Next, a magnetic recording layer 2 is laminated on the surface of the base 1.
can be formed by known oblique deposition. The magnetic recording layer 2 preferably contains 35% by weight or less of nickel, and in this case, the thickness of the magnetic recording layer is preferably 300 Å to 1500 Å. The intermediate layer 3 can be formed by coating it as a paint. The thickness of the middle layer 3 is the same as that of the lower layer 1.
It is desirable that the thickness be 0.5μ or less so as not to cause a spacing loss regarding the magnetic recording layer 2. A second magnetic recording layer 4 laminated on the surface of the intermediate layer 3
is the same as the first magnetic recording layer 2. The basic configuration of the present invention has been explained above, but the following things are also possible by using the present invention. Figure 2 shows an example of the use of the present invention.
A first magnetic recording layer 12, a first intermediate layer 13,
The second magnetic recording layer 14, the second intermediate layer 15, and the third magnetic recording layer 16 are sequentially laminated. In Figure 2, the magnetic recording layer consists of three layers, but it is also possible to form a magnetic recording medium with multiple magnetic recording layers by alternately forming an intermediate layer and a magnetic recording layer. This further increases the residual magnetic flux. Further, the magnetic recording medium of the present invention may be provided with a protective layer 5 as shown by 5 in FIG. 3, and by providing the protective layer 5 in this manner, corrosion resistance and runnability can be improved. The protective layer 5 can be formed by coating a suitable synthetic resin paint with the addition of wax, oil, etc. as a surfactant or lubricant, and furthermore, a pigment. When forming the protective layer, the solvent in the paint for forming the protective layer may soak the underlying intermediate layer and cause it to dissolve or swell, causing deformation such as cracks in the magnetic recording layer, so it is advisable to select a solvent. [Example] Example A polyethylene terephthalate film with a thickness of 6 μm was used as the substrate, and the film was run along a cooling drum with a diameter of 600 mm while the vacuum level was 5×10 ^-5 Torr.
Using an alloy of Co:Ni=8:2, vapor deposition was started at an incident angle of 90° with respect to the normal to the film, and the incident angle was continuously changed so that the incident angle was 55° at the end of the vapor deposition. A first magnetic recording layer having a thickness of 1000 Å was created by performing vapor deposition with different thicknesses. Next, on the first magnetic recording layer, a 2% solution (solvent: MEK/toluene = 1/1) of carboxyl group-containing polyvinyl chloride resin (Kobunshi Kagaku Kogyo Co., Ltd., Vinyl K2) was applied to a plate depth of 25 μm. An intermediate layer with a thickness of 0.25μ was formed by the gravure coating method using a gravure plate. Further, a second magnetic recording layer having the same thickness was formed on the intermediate layer under the same conditions as those used for forming the first magnetic recording layer. Comparative Example 1 The same procedure as in Example was used except that a 2% solution (solvent: MEK/toluene = 1/1) of an epoxy curable acrylic resin (Kotax LK761, manufactured by Toray Industries, Ltd.) was used to form the intermediate layer. Comparative Example 2 Same as Example, except that a 500 Å thick aluminum vapor deposited layer was used as the intermediate layer. The magnetic films obtained in the above Examples and Comparative Examples 1 and 2 were used as tapes with a width of 3.81 mm, and the results of evaluating the magnetic properties are shown in Table 1, and the results of evaluating the appearance, corrosivity, etc. are shown in Table 2. show.

【table】

[Table] [Operations and effects of the invention] The magnetic recording medium of the invention has a magnetic recording layer made of an alloy of cobalt and nickel formed by oblique evaporation on a substrate, and a polyvinyl chloride layer containing carboxyl groups. An intermediate layer made of a copolymer resin and a magnetic recording layer made of an alloy of cobalt and nickel mainly composed of cobalt and formed by oblique evaporation are sequentially laminated. Therefore, according to the present invention, even if the total thickness of the magnetic recording layer is increased, the magnetic properties such as residual magnetic flux will not deteriorate because the magnetic recording layer is formed into multiple layers with an intermediate layer interposed therebetween. Furthermore, since the intermediate layer uses a polyvinyl chloride copolymer resin containing carboxyl groups, it has good adhesion to the magnetic recording layer made of an alloy of cobalt and nickel. This has the effect of inducing a crystal orientation that optimizes the magnetic properties of the second magnetic recording layer.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the magnetic recording medium of the present invention, Figure 2 is a cross-sectional view of the magnetic recording medium of the present invention;
Both FIG. 3 and FIG. 3 are sectional views showing an example of the use of the present invention. 1, 11...Base, 2, 4, 12, 14, 16
...Magnetic recording layer, 3...Intermediate layer, 5...Protective layer.

Claims (1)

[Scope of utility model registration request] On the substrate, a magnetic recording layer made of an alloy of cobalt and nickel mainly composed of cobalt formed by oblique evaporation, an intermediate layer made of a polyvinyl chloride copolymer resin containing carboxyl groups, and a cobalt-based main layer formed by oblique evaporation. A magnetic recording medium comprising a magnetic recording layer made of an alloy of nickel and nickel, which are sequentially laminated.