JPH0744926A - Information recording medium - Google Patents

Abstract

(57) [Abstract] [Purpose] In a magnetic recording layer of an information recording medium, it is an object to structure the adhesiveness of a print layer and a print protection layer to a concealing layer to improve durability. A magnetic recording layer is provided on the opposite surface of a disk-shaped recording medium having an optical recording layer, and the magnetic recording layer is a magnetic layer 5, a hiding layer 6, a printing layer 8, and a print protection layer on a non-magnetic support 4. 9 is a magnetic recording layer formed by coating sequentially, and the concealing layer 6 has a vortex cell structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium, and more particularly to an information recording medium provided with a magnetic recording layer capable of recording and reproducing magnetic recording on a CD or MD.

[0002]

2. Description of the Related Art In recent years, the development of CDs and MDs has made great strides, and higher performance is required. Further, there has been a demand for development of a medium having a recording / reproducing function of magnetic recording for a CD or MD having only a reproducing function. In these media, the magnetic layer and the concealing layer as the underlying layer for the level printing on the magnetic layer, and the print layer and the print protection layer are further formed thereon (see FIG. 1). Here, it goes without saying that it is necessary for each layer to have sufficiently strong adhesiveness. That is, when the adhesion between the hiding layer and the printing layer is weak, the printing layer is more easily peeled off than the hiding layer, and even when the adhesion between the printing protection layer and the hiding layer is weak, the printing layer is more easily peeled off than the hiding layer. .

By the way, in order to improve the adhesiveness of the print layer and the print protection layer to the concealment layer, there has been no special technique in the prior art. Among the conventional techniques, corona discharge treatment to the hiding layer is effective for a short time and is therefore not very effective.Also, even if the resin system of the hiding layer is improved to improve wettability, the method is still effective. There was a limit to it. In addition, the actual situation is that there is almost no useful technical content disclosed.

[0004]

In the information recording medium of the present invention, how to improve the concealment layer is a problem in order to improve the adhesiveness of the printing layer and the print protection layer to the concealment layer.

[0005]

In order to solve this problem, the present invention provides the concealing layer with a vortex cell structure.

[0006]

[Function] Vortex Cell
The structure is also called Yuzu skin, and has a hexagonal pattern (groove) on the surface of the coating film. It is known that the mechanism of occurrence of this structure is due to the convection of the paint in the stages from the drying of the paint to the formation of the coating film. As a result of diligent studies, the present inventor has found that the printing paint intrudes into the hexagonal pattern (groove) of the vortex cell structure and cannot be easily removed. That is, a part of the printing layer that penetrates the hexagonal groove that is the concave portion acts as an anchor that partly digs into the hiding layer, and as a result, the adhesion of the printing layer to the hiding layer is improved. (See FIG. 1).
Further, in the absence of the print layer, the print protection layer comes into direct contact with the hiding layer, but even in this case, a part of the print protection layer also bites into the hexagonal groove, and thus the hiding layer is formed. The adhesiveness between the protective layer and the print protection layer is improved. The significance of this is important. That is, since the vortex cell structure can be easily realized by decreasing the viscosity of the coating material, the durability of the printing layer can be improved by improving the adhesiveness by a very simple method.

[0007]

EXAMPLES Examples of the present invention will be specifically described below. First, examples in which titanium oxide is used in the coating material for the hiding layer to form a vortex cell structure are described as Examples 1 to 3, and cases in which it is not used are Comparative Examples 1 to 3. The following materials are mixed and dispersed in the following formulation to prepare a paint for a hiding layer. Titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., product number; R-580, particle size 0.28 μm) --- 100 parts by weight PVC copolymer resin (manufactured by Nippon Zeon Co., Ltd., product number; MR-110) ) -10 parts by weight Polyurethane resin (manufactured by Toyobo Co., Ltd., product number: UR-8530) ... 10 parts by weight Mixed organic solvent (MEK / toluene / cyclohexanone)
= 3/3/1 (weight ratio) is adjusted and added so that the paint has each NV (% by weight of non-volatile components) as described in (Table 1). Further, the viscosity was measured using a B-type viscometer (BM type, manufactured by Tokyo Keiki Co., Ltd.), No. 1 rotor, 6
The measurement was performed under the conditions of rpm and 25 ° C.

Then, similarly, the following materials are mixed and dispersed,
Prepared as a paint for magnetic layer. 100 parts by weight of Ba ferrite magnetic powder (manufactured by Toshiba Corp., product number; BFG-30V8) PVC copolymer resin (manufactured by Nippon Zeon Co., Ltd., product number; MR-110) 13 parts by weight Polyurethane resin (Toyobo Co., Ltd. ), Product number; UR-8530) ... 6 parts by weight Mixed organic solvent (MEK / toluene / cyclohexanone)
= 3/3/1 (weight ratio) is adjusted and added so that the coating material has NV = 32%.

The hiding layer coating material and the magnetic layer coating material are both
It was sufficiently dispersed and prepared by a sand mill. Next, the coating material for the magnetic layer is first applied onto a PET base having a thickness of 62 μm by using a general-purpose coating machine to form a magnetic layer (thickness of 5 μm), and the coating material for the concealing layer is similarly applied thereon. Then, a concealing layer (thickness of 3 μm) was formed to form a two-layer film, which was subjected to calendar treatment at 90 ° C.-300 kg / cm, and this sample coating film was observed with an optical microscope (NIKON (AFX-2)). The vortex cell structure of the hiding layer was observed and photographed.

The results are shown in (Table 1). In addition, FIG. 2 shows an optical microscope photograph of samples in which the film thickness of the coating film was changed. However, the photographic magnification is 110 times.

[0011]

[Table 1] As shown in the results of Table 1 and FIG. 2, the vortex cell structure is better developed as the viscosity of the hiding layer coating material is lower and the thickness of the coating film is thicker. Further, a print layer and a print protection layer were formed. A general-purpose UV resin is used for the printing layer and the printing protection layer, and the printing liquid is also a UV resin ink. The total film thickness of both layers is 3 μm. The following durability test was performed on this sample.

A sample coating film composed of a PET base, a magnetic layer, a concealing layer, a printing layer, and a printing protection layer as described above was punched out into a 3.5 inch-FD size, and two FDs thereof were cut.
The bases are adhered to each other with an adhesive to form a medium for a double-sided coating layer. This medium is put in a FD cell case, and FDD for 3.5 inch FD (manufactured by Matsushita Communication Industrial Co., Ltd., product number; J
U-253) was subjected to a durability test for 7 days at room temperature and normal humidity. The head position was Tr = 16, and the disk rotation speed was 300 rpm. The degree of disorder of the characters in the print layer as a result of this is displayed in 5 levels by visual judgment. Characters on printed layer are perfect ... ・ Index = 5 Characters on printed layer are almost perfect ・ Index = 4 Characters on printed layer are slightly rubbed ・ Index = 3 Characters on printed layer are slightly rubbed Table 2 shows the results of the judgment of each sample based on the above criteria.

[0013]

[Table 2] As shown in the results of (Table 2), it is apparent that the examples show good results in comparison with the comparative examples.

[0014]

As is clear from the above results, the durability is obviously improved when the concealing layer has the vortex cell structure as compared with the case where it is not. The reason for this is
It is considered that the durability is also improved by improving the adhesiveness of the print layer and the print protection layer to the hiding layer.

[Brief description of drawings]

FIG. 1 is a sectional view of an information recording medium showing an embodiment of the present invention.

FIG. 2 is an optical micrograph showing various film thicknesses of a hiding layer in Example 1.

[Explanation of symbols]

 1 CD 2 CD Pit 3 Adhesive 4 Nonmagnetic Support 5 Magnetic Layer 6 Hiding Layer 7 Vortex Cell Structure 8 Printing Layer 9 Printing Protection Layer

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[Procedure amendment]

[Submission date] February 1, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a sectional view of an information recording medium showing an embodiment of the present invention.

2 is an optical micrograph showing the grain structure of various thicknesses of the masking layer in Example 1. FIG.

[Explanation of symbols] 1 CD 2 CD pit 3 Adhesive 4 Non-magnetic support 5 Magnetic layer 6 Hiding layer 7 Vortex cell structure 8 Printing layer 9 Printing protection layer

Claims (1)

[Claims] 1. An information recording medium in which a magnetic recording layer is provided on the opposite side of a disk-shaped recording medium having an optical recording layer or a magneto-optical recording layer, the magnetic recording layer being a magnetic layer on a non-magnetic support,
An information recording medium, which is a magnetic recording layer formed by sequentially coating a hiding layer, a printing layer, and a printing protection layer, wherein the hiding layer has a vortex cell structure.