JPH10219433A - Method for vapor deposition on flexible base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor deposition method capable of preventing the rupture, etc., of a flexible base (base film) even when the acceleration voltage of an electron beam is increased at the time of vapor deposition of a ferromagnetic metal on the base film in production of magnetic recording media, etc. SOLUTION: This method for vapor deposition on the flexible base consists in irradiating the metal 10 for vapor deposition in a crucible 8 with an electron beam and depositing the metal on the surface of the flexible base transported along the surface of a cooling drum 5 from the aperture of a shielding plate 4. The shielding plate 9 is kept open during the evaporation rate of the metal for vapor deposition in the crucible attains the desired rate. The degree of the opening is kept in such a manner that the min. opening angle (θmin) formed by the line connecting the aperture and the metal for vapor deposition and the line connecting the contact point with the cooling drum and the line connecting the contact point and the center of the cooling drum attains 65 to 85 deg.. The shielding plate is then opened to the prescribed degree after the evaporation rate of the metal attains the desired rate. The metal is deposited by evaporation on the surface of the flexible base from the aperture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for vapor deposition on a flexible support, and more particularly to a method for producing a magnetic recording medium.
A method of vapor deposition on a flexible support that can easily prevent breakage of the base film even when the accelerating voltage of the electron beam is increased upon vapor deposition of the ferromagnetic metal on the flexible support (base film) About.

[0002]

2. Description of the Related Art Conventionally, in the production of magnetic recording media and the like, for example, when forming a magnetic recording layer, a long flexible support (base film) is coated with a Co, Co-Ni alloy, or another Co alloy. Is formed by depositing a ferromagnetic metal such as a metal thin film (magnetic recording layer) by a vapor deposition method.

In such a metal vapor deposition method, for example, a base film fed from a feed roll is conveyed along the surface of a cooling drum in a vacuum chamber. Irradiate a high energy electron beam under pressure, deposit metal at a predetermined angle on the base film to form a metal thin film,
This is taken up by a take-up roll.

Conventionally, in such a vapor deposition method, for example, a vessel such as a crucible containing a metal for vapor deposition is separated from the cooling drum and an openable and closable shield plate in a vacuum chamber, and the metal for vapor deposition is disposed. Irradiate the electron beam, until the vapor deposition is possible, that is, until the amount of metal evaporation reaches the desired amount, the shield plate is completely closed, and only after reaching the desired amount of metal evaporation The shielding plate was opened for vapor deposition, and metal vapor was vapor-deposited on the base film from this opening.

In recent years, the performance of magnetic recording media has been improved,
High precision and high productivity are required, and the acceleration voltage of the electron beam is further increased.
Vapor deposition has been performed with an electron beam having a power of about 40 to 50 kV.

However, when the accelerating voltage of the electron beam is increased, the metal for deposition is irradiated with the electron beam as in the prior art, and the shielding plate is closed until the evaporation amount of the metal reaches a desired amount. The shielding plate is opened for the first time after the amount of metal evaporation reaches a desired amount, and when metal vapor is vapor-deposited on the flexible support through this opening, the flexible support is affected by the secondary electrons of the electron beam. Of the flexible support, the discharge occurs when the flexible support is separated from the cooling drum, the end face of the flexible support is scratched, and the flexible support is broken. Therefore, in order to prevent electrification, for example, a method of providing an antistatic / static elimination device or the like before and after the cooling drum, or applying a vibration to the flexible support to eliminate static, and the like, are performed. The effect is not sufficiently satisfactory.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and particularly, in the manufacture of a magnetic recording medium or the like, when a ferromagnetic metal is deposited on a flexible support (base film), an It is an object of the present invention to provide a method for vapor deposition on a flexible support that can easily prevent breakage of the base film even when the acceleration voltage of the beam is increased.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems, and as a result, until the metal for evaporation is irradiated with an electron beam so that the metal can be vapor-deposited, the conventional metal is used. The shield plate is completely closed, and the flexible support, which is the object to be deposited conveyed on the cooling drum, completely shields the space between the metal vapor atmosphere and the shield plate is opened for the first time at the start of deposition.
Instead of depositing metal vapor on the flexible support through the opening, the metal is irradiated with an electron beam, and the shielding plate is opened to a predetermined degree until the amount of metal evaporation reaches a desired amount. By placing the flexible support under a metal vapor atmosphere capable of being vapor-deposited, and then, at the time of main vapor deposition, by opening the opening of the shielding plate to a predetermined extent for main vapor deposition and starting vapor deposition,
The inventors have found that the above problems can be solved, and have completed the present invention based on the findings.

That is, the present invention provides a cooling drum for transporting a flexible support along its surface, a shield plate which can be opened and closed, and a metal for vapor deposition which is spaced apart from the cooling drum via the shield plate. In a vacuum vessel provided with a crucible containing a crucible, a surface of a flexible support which is irradiated with an electron beam to the metal for vapor deposition in the crucible and is conveyed along the surface of the cooling drum from the opening of the shielding plate. In the method for vapor-deposition on a flexible support for vapor-depositing a metal, a metal plate is irradiated with an electron beam, and the shielding plate is opened until the evaporation amount of the metal for vapor deposition in the crucible becomes a desired amount. At the same time, the minimum opening angle (θmin) between the line connecting the opening and the metal for vapor deposition and the contact between the cooling drum and the line connecting the contact and the center of the cooling drum is 65 °. ~ 85 ° and then gold Evaporation amount is a predetermined extent opening the shielding plate after reaching a desired amount, characterized in that depositing a metal on the flexible support surface through the opening, the method relates to the deposition of the flexible support.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing an example of the vapor deposition method of the present invention. In FIG. 1, a delivery roll 2, a cooling drum 5, and a take-up roll 3 are provided in a vacuum chamber 1, and a flexible support (base film) 4 delivered from the delivery roll 2 is moved in the direction of the arrow. It is conveyed along the rotating cooling drum 5 and wound up on the winding roll 3.

At a predetermined position outside the cooling drum 5, a shield plate 9 which can be opened and closed is disposed, and a container (crucible) 8 containing a metal 10 for vapor deposition and the metal 1 for vapor deposition via the shield plate 9.
An electron gun 6 for irradiating the electron beam 7 to the electron beam 0 is provided.

The metal 10 for vapor deposition accommodated in the crucible 8 is melted by irradiating the electron beam 7 generated from the electron gun 6, and the generated metal vapor flows through the opening of the shielding plate 9. At 11, it is deposited on the base film 4 running on the cooling drum 5 to form a magnetic thin film.

Here, the structure of the shielding plate 9 can be freely opened and closed.
There is no particular limitation as long as the openings are formed to a desired extent during metal deposition. In the drawing, a configuration including a front shielding plate 9a and a rear shielding plate 9b is illustrated, and at the time of shielding, the rear end of the front shielding plate 9a and the front end of the rear shielding plate 9b are in contact with each other. Upper base film 4 and metal 1 for vapor deposition
Cut off between 0. At the time of opening, the front shielding plate 9a
The front end of the rear shield plate 9b is separated from the rear end of the rear shield plate 9b. The front shielding plate 9a and the rear shielding plate 9
b is made of an iron steel plate such as “SUS 304”,
The means for opening and closing the shield plate can be performed by, for example, a rack and pinion, but is not limited to this. In addition, conventionally known materials can be used for the material of the shielding plate and the opening / closing means.

In such a vacuum vapor deposition method, the conventional shielding plate 9 is closed until the vapor deposition metal 10 in the crucible 8 is melted and the metal vaporization amount reaches a desired amount, and the base film 4 is made of metal vapor. Although it was not exposed to the atmosphere, in the present invention, as shown in FIG. 2, from the start of melting of the metal (at the start of electron beam irradiation) to the time when the amount of evaporated metal reaches a desired level, The shielding plate 9 is opened, and the degree of the opening is determined by the contact (S) between the line connecting the opening and the metal 10 for vapor deposition and the cooling drum 5, and the contact (S).
It is characterized in that a minimum opening angle (θmin) formed by a line connecting the cooling drum 5 and the center (O) is kept at 65 ° to 85 °. By setting in this way, it is possible to prevent the occurrence of defective products (such as breakage) during vapor deposition, and it is possible to reduce the production loss.

Here, the minimum opening angle (θmin) is 8
If it exceeds 5 °, similar to the state where the conventional shielding plate is closed,
Problems such as breakage of the base film due to electric discharge at the time of peeling from the cooling drum occur. On the other hand, when the angle is less than 65 °, the opening area becomes large, and the base film breaks due to heat loss due to radiant heat or the like.

In the present invention, "between irradiating the metal for deposition with an electron beam and the amount of evaporation of the metal for deposition in the crucible reaching a desired amount" is defined as follows. That is, when the melting of the metal for vapor deposition is started by irradiating the electron beam, the melted metal portion in the crucible is evaporated, while the melting of the remaining unmelted metal portion proceeds in parallel.
While the evaporation of the molten metal and the melting of the unmelted metal are performed in parallel, the evaporation rate of the metal is not constant but gradually increases, but generally, all the metal in the crucible is completely removed. Upon melting, a certain amount of evaporation is obtained by the input power of the electron beam, and the evaporation rate of the metal is constant. “Between irradiating the metal for deposition with an electron beam and evaporating the amount of the metal for deposition in the crucible to a desired amount” means, specifically, a constant rate of evaporation of the metal from the start of the electron beam irradiation. Until it is done. In addition, this constant metal evaporation rate is set in consideration of various requirements, such as the running speed of the base film, the size of the vacuum chamber, the amount of metal contained in the crucible, and the like, according to the required metal deposition thickness. be able to. This constant speed is generally 5000 Na / sec per m ²
If the value is c or more, a preferable production scale is obtained, but the present invention is not limited to this.

The minimum opening angle (θmin) is 65 ° or more.
While keeping at 85 °, the running speed of the base film 4 may be set within a range that does not cause loss of the product and is not affected by radiant heat due to the opening of the shielding plate 9 to a predetermined degree. Usually, the transport speed during vapor deposition (100 to 2
00m / min) to about one-tenth to one-tenth
The value may be about 50 m / min. This speed can be changed as appropriate, such as keeping the speed constant while the shield plate is open, or increasing the speed sequentially according to the degree of melting of the metal (change in the amount of evaporation of the metal).

Next, after the metal evaporation amount reaches a desired amount, the shielding plate is opened to a predetermined degree, and the metal is fully deposited on the surface of the flexible support through the opening. However, the opening amount of the shielding plate at the time of the main vapor deposition may be approximately the same as the minimum opening angle (θmin) at the time of melting the metal, or may be narrowed or widened.

In the present invention, conventionally known materials can be used for the vapor deposition device, metal or alloy for vapor deposition, base film and the like.

As the base film (flexible support), for example, a plastic film such as polyethylene terephthalate, polyethylene naphthalate, polyamide, polyamide imide, or polyimide; a long flexible support made of paper or metal foil; And there is no particular limitation. Further, the base film may be one in which various processing layers are formed in advance.

The metal for vapor deposition is not particularly limited, but examples thereof include ferromagnetic metals. Of these, cobalt, cobalt alloys, metals containing Fe and Cr are preferably used, and particularly, cobalt and cobalt alloys are preferably used, but are not limited thereto.

[0023]

Next, the present invention will be described in more detail with reference to examples.

Example 1 After the pressure of the vacuum chamber 1 in FIG. 1 was reduced to 1 × 10 ⁻⁴ Torr or less, the shielding plate 9 was moved to the minimum opening angle (θmi) shown in FIG.
n) Magnesia crucible 8 set at 85 °
Of cobalt (Co) is irradiated with an electron beam 7 having a power of 40 kV by an electron gun 6 to start melting, and a polyester base film (thickness 7 μm) is formed as a base film 4 on a cooling drum 5 having a diameter of 1 m by 10 m / cm. Minute, the cobalt is dissolved, and when the evaporation amount of the metal reaches 5000 na / sec per 1 m ² , the traveling speed of the base film 4 is increased to 100 m / min to perform vapor deposition.
A metal thin film (0.2 μm thickness) was formed.

Embodiment 2 In Embodiment 1, the minimum opening angle (θmin) is set to 70 °.
The vapor deposition was performed in the same manner as in Example 1 except that the above conditions were satisfied.

Embodiment 3 In Embodiment 1, the minimum opening angle (θmin) is 65 °.
The vapor deposition was performed in the same manner as in Example 1 except that the above conditions were satisfied.

Comparative Example 1 In Example 1, the minimum opening angle (θmin) was 90 °.
Except for (FIG. 3), vapor deposition was performed in the same manner as in Example 1.

Comparative Example 2 In Example 1, the minimum opening angle (θmin) was set to 60 °.
The vapor deposition was performed in the same manner as in Example 1 except that the above conditions were satisfied.

Steam Examples 1 to 3 and Comparative Examples 1 and 2
The charging of the base film and the damage to the base film were evaluated according to the following evaluation criteria. Table 1 shows the results. [Breakage due to Charging of Base Film] The state of the base film during vapor deposition was visually confirmed, and the breakage due to charging was evaluated. [Heat Loss of Base Film] The state of the base film during vapor deposition was visually confirmed, and the heat loss was evaluated.

[0030]

[Table 1] As is clear from the results in Table 1, the base films deposited by the deposition method of the present invention did not lose heat, did not break, and the like, and good results were obtained. On the other hand, when the minimum opening angle (θmin) of the shielding plate exceeds 85 °, the amount of metal deposited on the running base film is small, so that there is almost no effect of preventing charging by secondary electrons, and breakage during running of the base film is prevented. I couldn't do that. Further, when the minimum opening angle (θmin) of the shielding plate was less than 65 °, the base film was thermally damaged by radiant heat from the evaporation source, causing heat loss.

[0031]

As described in detail above, according to the present invention,
When the ferromagnetic metal is vapor-deposited on the flexible support (base film), even when the acceleration voltage of the electron beam is increased, it is possible to easily prevent the base film from breaking or the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of a vacuum evaporation apparatus used in an evaporation method of the present invention.

FIG. 2 is an explanatory diagram of a minimum opening angle (θmin) of the present invention.

FIG. 3 is a diagram showing an aspect of a minimum opening angle (θmin) in Comparative Example 1.

[Description of Signs] 1 Vacuum tank 2 Feeding roll 3 Winding roll 4 Flexible support (base film) 5 Cooling drum 6 Electron gun 7 Electron beam 8 Crucible 9 Shielding plate 9a Front shielding plate 9b Rear shielding plate 10 For vapor deposition Metal 11 Steam steam flow of metal

 ──────────────────────────────────────────────────の Continuing on the front page (72) Nobuo Ariga Inventor, 1-13-1, Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation

Claims (1)

[Claims] 1. A cooling drum for transporting a flexible support along its surface, a shield plate that can be opened and closed, and a metal for vapor deposition that is spaced apart from the cooling drum via the shield plate. In a vacuum vessel provided with a crucible, the metal for vapor deposition in the crucible is irradiated with an electron beam, and the metal is deposited on the surface of the flexible support conveyed along the surface of the cooling drum from the opening of the shielding plate. In the method of vapor deposition on the flexible support to be vapor-deposited, irradiating the vapor-deposited metal with an electron beam until the evaporation amount of the vapor-deposited metal in the crucible becomes a desired amount, while opening the shielding plate, The degree of the opening is determined by the minimum opening angle (θmi) formed by the line connecting the opening and the metal for vapor deposition with the contact point between the cooling drum and the line connecting the contact point and the center of the cooling drum.
n) is kept at 65 ° to 85 °, and after the metal evaporation amount reaches a desired amount, the shielding plate is opened to a predetermined degree, and metal is vapor-deposited from the opening on the surface of the flexible support. A method for vapor deposition on a flexible support, characterized in that: