JPS61139932A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent the wrinkling in the vapor deposition stage of a ferromagnetic material by adjusting the temp. of a base to support a plastic substrate to the temp. lower by 50-90 deg.C than the glass transition temp. of the substrate in the vapor deposition stage. CONSTITUTION:The plastic substrate 4 consisting of a polyester film, etc. having <=0.01mum average center line roughness Ra and 20-100 deg.C glass transition temp. is taken up on a roll 6 from a roll 5 along the circumferential surface of a cooling drum 3. A ferromagnetic material 8 of a ferromagnetic material vapor source 7 in a vacuum vessel 1 is deposited by evaporation on the substrate 4. The drum surface is adjusted to the temp. lower by 50-90 deg.C than the glass transition temp. of the substrate by the heating and cooling source contained in the drum 3. The substrate 4 is thus prevented from elongating and hardening by adjusting the surface temp. of the drum by which the wrinkling thereof is satisfactorily suppressed and the quality of the recording medium is improved.

Description

[Detailed Description of the Invention] [Technical Field and Objectives] The present invention relates to a method for manufacturing a magnetic recording medium having a ferromagnetic metal thin film layer as a recording layer, and the object thereof is to prevent the formation of the ferromagnetic metal thin film layer from It is an object of the present invention to provide a method for manufacturing the above-mentioned wrinkle-free magnetic recording medium by suppressing wrinkles.

[Background technology]

Magnetic recording media with a ferromagnetic metal thin film layer as a recording layer are usually produced by moving a plastic substrate such as a polyester film along the circumferential side of a cylindrical cooling drum installed in a vacuum chamber, and applying a ferromagnetic material to the substrate. The cooling drum is usually cooled to a certain temperature or lower.

However, when using a plastic substrate with a good surface quality with a center line average roughness Ra of 0.01 μm or less, using a conventional cooling drum cooled to a certain temperature or less may not be sufficient when the plastic substrate is made of different materials. If this is not possible and the temperature of the cooling drum is too high for the plastic substrate used, the effect of radiant heat from the ferromagnetic material evaporation source cannot be sufficiently suppressed, causing the plastic substrate to stretch and damage the plastic. Wrinkles appear on the board.

Additionally, if the temperature of the cooling drum is too low for the plastic substrate being used, the plastic substrate will harden and the uneven tension caused by misalignment of the roll system cannot be alleviated, causing wrinkles on the plastic substrate. .

[Summary of the invention]

In order to improve this drawback, the present invention has conducted various studies on supports for supporting plastic substrates such as cooling drums, and as a result, the temperature of the support has been adjusted so that the center line average roughness Ra is 0.
01 μm or less and a glass transition temperature of 20°C to 100°C
50% higher than the glass transition temperature of the plastic substrate within the range of
When the temperature is adjusted to a low temperature of ~90'C and the ferromagnetic material is directed from the ferromagnetic material evaporation source to the plastic substrate moving along the support and vacuum evaporation is performed, the plastic moving along the support is evaporated. This method was developed based on the discovery that the generation of wrinkles can be effectively suppressed by adjusting the temperature during vapor deposition of the substrate to an appropriate temperature. The temperature of a support supporting a plastic substrate with a glass transition temperature within the range of 20°C to 100°C was adjusted for 8 cycles to a temperature 50°C to 90°C lower than the glass transition temperature of the plastic substrate, and the temperature was adjusted along this support. The method is characterized in that a ferromagnetic material is directed from a ferromagnetic material evaporation source onto a moving plastic substrate to form a ferromagnetic metal thin film layer.

The present invention will be described below with reference to the drawings.

Figure 1 shows a cross-sectional view of the vacuum evaporation apparatus,
is a vacuum chamber, and the inside of this vacuum chamber 1 is maintained in a vacuum by an exhaust system 2. 3 is a cooling drum disposed in the center of the vacuum chamber 1, and is made of a polyester film or the like having a center line average roughness Ra of 0.01 μm or less and a glass transition temperature of 20°C.
The plastic substrate 4 within the range of ~100°C is moved from the raw roll 5 along the circumferential side of this cooling drum 30,
It is wound up on a winding roll 6. During this time, cooling drum 3
A ferromagnetic material 8 is heated and evaporated in a ferromagnetic material evaporation source 7 disposed at the bottom of the vacuum chamber 1 facing the plastic substrate 4 moving along the circumferential side of the plastic substrate 4 . vacuum deposition is performed.

Here, the cooling drum 3 disposed in the center of the vacuum chamber 1 has a built-in heater and a refrigerant circulation pipe, and is heated or cooled and moves along the circumferential side of the cooling drum 3. Depending on the material of the plastic substrate 4, the temperature is adjusted to be 50 to 90 degrees Celsius lower than its glass transition temperature. As described above, the temperature of the cooling drum 3 is preferably 50°C to 90°C lower than the glass transition temperature of the plastic substrate 4. The action of radiant heat from the evaporation source 7 cannot be sufficiently suppressed, and the plastic substrate stretches and wrinkles occur on the plastic substrate.
Further, at a temperature that is 90° C. or more lower than the glass transition temperature of the plastic substrate 4, the plastic substrate is hardened and uneven tension cannot be alleviated, causing wrinkles in the plastic substrate. Therefore, the plastic substrate 4 moving on the circumferential surface of the cooling drum 3 is always adjusted to an appropriate temperature that is 50 to 90 degrees Celsius lower than its glass transition temperature. This prevents the plastic substrate from becoming too hard (and the generation of wrinkles is well suppressed. In addition, although the drawing shows an example in which the cooling drum 3 is used as a support for the plastic substrate 4, The body is not limited to such a cooling drum 3, but may be of any shape or shape as long as it can support the plastic substrate 4 and control the temperature to 50'C to 90C lower than the glass transition temperature of the plastic substrate 4. It may be of any material.

As the plastic substrate, commonly used materials such as polyester, polyvinyl chloride, and polyamide are suitably used, and those with a glass transition temperature in the range of 20°C to 100°C are preferably used. The temperature is also adjusted to an appropriate temperature, which is 50°C to 90°C lower than the glass transition temperature, and the generation of wrinkles is sufficiently suppressed.

In addition, to form a ferromagnetic metal thin film layer, commonly used ferromagnetic materials such as single metals such as cobalt, nickel, and iron, their alloys or oxides, and Co-P and Co-Ni-P are heated in a vacuum. It is formed by vapor deposition.

〔Example〕

Next, embodiments of the invention will be described.

Examples 1 to 5 A ferromagnetic material was deposited using the vacuum evaporation apparatus shown in Fig. 1 on a polyester base whose surface had a centerline average roughness Ra of 0.0040 μm, a thickness of 10 μm, and a glass transition temperature of 70°C. The film 4 was moved along the circumferential surface of the cooling drum 3 from the original fabric roll 5 and set to be wound up on the take-up roll 6, and cobalt 8 was set in the ferromagnetic material evaporator #7. Next, the inside of the vacuum chamber 1 is pumped approximately 5X using the exhaust system 2.
The vacuum was evacuated to 10-5 Torr, and the cobalt 8 in the ferromagnetic material evaporation source 7 was heated and evaporated, and the polyester base film 4 was run at a speed of 50 m/min, and the temperature of the cooling drum 3 was set as shown in Table 1 below. As shown, from 20℃ to -2
Vacuum deposition is performed in 5 stages at a temperature of up to 0°C.
A ferromagnetic metal thin film layer made of cobalt and having a thickness of 1000 nm was formed on the polyester base film 4. After that, it was cut to a predetermined width to make magnetic tape.

Comparative Examples 1 to 5 In Examples 1 to 5, the temperature of the cooling drum 3 was controlled in five stages within the range of 30°C or higher and -30°C or lower, as shown in Table 1 below. Magnetic tapes were produced in the same manner as in Examples 1 to 5, except for the following.

The magnetic tapes obtained in each Example and each Comparative Example were observed for the presence or absence of wrinkles.

Table 1 below shows the results.

Table 1 [Effects of the Invention] As is clear from Table 1 above, the magnetic tape ( No wrinkles were observed in any of Examples 1 to 5), but those in which the temperature of the cooling drum was higher than this range (Comparative Examples 1 to 3) and those in which it was lower (Comparative Examples 4 and 5)
The occurrence of wrinkles was observed, which indicates that according to the manufacturing method of the present invention, the generation of wrinkles can be effectively suppressed and a wrinkle-free magnetic recording medium can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing one example of a vacuum evaporation apparatus used to carry out the manufacturing method of the present invention.

Claims (1)

[Claims] 1. A support that supports a plastic substrate running in a vacuum atmosphere and having a centerline average roughness Ra of at least one side of 0.01 μm or less and a glass transition temperature within the range of 20°C to 100°C during ferromagnetic material deposition. The temperature of the plastic substrate is adjusted to a temperature range of 50° C. to 90° C. lower than the glass transition temperature of the plastic substrate, and a vapor flow of the ferromagnetic material is directed from a ferromagnetic material evaporation source to the plastic substrate moving along the support. A method for producing a magnetic recording medium characterized by forming a ferromagnetic metal thin film layer.