JPH0744925A - Information recording medium - Google Patents

Abstract

PURPOSE:To improve adhesion property of a hiding layer with a print layer and print protecting layer by coating a nonmagnetic supporting body successivery with a magnetic layer, hiding layer, print layer and print protecting layer to constitute a magnetic recording layer and forming the hiding layer to have a vortex cell structure. CONSTITUTION:A magnetic layer 5 is formed on a nonmagnetic supporting body 4 by applying the coating material essentially comprising a Ba ferrite magnetic powder. The opposite side of the supporting body has a CD 1 having pits 2 of CD adhered with an adhesive 3. Then, a coating material essentially comprising titanium oxide in which a resin and mixing org. solvent is mixed and dispersed is applied on the layer 5 and subjected to calendering to form a hiding layer 6 having a vortex cell structure 7. Then, a UV-curing resin and UV-curing resin ink are used to form a print layer 8 and a print protecting layer 9 on the layer 6. The magnetic recording layer consists of the layers 5-9. By this method, the coating material for printing intrudes into hexgonal grooves in the structure 7 to give an effect as an anchor so that strong adhesion is obtd. between the layer 6 and the layers 8, 9. Thus, durability of the layers 8, 9 is increased.

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, in the case of using titanium oxide in the coating material for the hiding layer to form a vortex cell structure, Examples 1 to 3,
The case where it is not described will be described as 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.

Next, 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 calendered at 90 ° C.-300 kg / cm. The coating film of this sample was observed with an optical microscope (NIKON (AFX-2)) to observe the vortex cell structure of the concealing layer and photographed.

The results are shown in (Table 1). In addition, a photograph of an optical microscope of a sample in which the film thickness of the coating film is changed is shown as (Table 2).

[0013]

[Table 1]

[0014]

[Table 2] As shown in the results of (Table 1) and (Table 2), the lower the viscosity of the coating material for the hiding layer and the thicker the coating film, the better the vortex cell structure developed.

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 3 shows the results of the judgment of each sample based on the above criteria.

[0017]

[Table 3] As shown in the results of (Table 3), it is apparent that the examples show good results in comparison with the comparative examples.

[0018]

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.

[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

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.