JP2005078731A - Method for manufacturing magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic recording medium with excellent manufacturing efficiency by eliminating the problem of a traveling defect due to electrostatic charge in a process for manufacturing a vapor deposition type medium by using an aromatic PA film. <P>SOLUTION: At the time of forming a magnetic layer of a metallic thin film by vacuum vapor deposition on a long-sized nonmagnetic substrate 1 composed of the aromatic PA as a principal component while allowing the nonmagnetic substrate 1 to travel along a cooling drum 2, a plate material (a shielding plate) 5 is arranged between the nonmagnetic substrate 1 and a vapor deposition source 9 so as to cover at least the transverse end 1a of the nonmagnetic substrate 1 and a metallic vapor deposition film thinner than the film thickness of the magnetic layer of the metallic thin film is formed at the the transverse end 1a at an average film thickness 5 to 30 nm. The region where the metallic vapor deposition film is formed is confined adequately to a region of a width 1 to 3 mm of the transverse end 1a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a magnetic recording medium (hereinafter, also simply referred to as “medium”), and more particularly, to a method for manufacturing a magnetic recording medium that prevents the occurrence of poor running due to charging by improving the vapor deposition process.

  As one type of magnetic recording medium, there is a so-called vapor deposition type magnetic recording medium in which a metal thin film is formed by vapor deposition on a polymer film as a nonmagnetic substrate (base). The vapor deposition type medium does not contain a binder as compared with the coating type medium, so the filling rate of the magnetic layer is high, the saturation magnetization can be increased, and the film can be thinned, so that the wavelength is short. This has the advantage of being advantageous in high-density recording, such as being able to suppress recording demagnetization.

  In the vapor deposition process for producing such a vapor deposition type medium, the vapor deposition source metal is heated using an electron beam, so that the polymer film loses heat due to the radiant heat or heat of the evaporated particles, and breaks or the like. Manufacturing defects may occur. Therefore, a shield plate (mask) that can be opened and closed is usually placed between the deposition source metal and the polymer film to block heat, or deposition is performed while the polymer film is running along the cooling drum. The technique is used to prevent heat loss.

  In particular, the width direction end of the polymer film (the width direction end, that is, the corner formed by the surface having the width and the surface having the thickness and the vicinity of the width direction), the so-called ear end, Even when the polymer film is run along the cooling drum with tension applied in the longitudinal (running) direction, it tends to lift (separate) from the surface of the cooling drum, so that heat loss is likely to occur. In addition, contamination of the cooling drum may occur due to adhesion of vapor deposition particles. When this contamination accumulates on the drum, the polymer film rides on the drum and cooling by the cooling drum does not sufficiently propagate to the film. This also causes heat loss. Therefore, from the viewpoint of preventing the occurrence of these problems, a technique is used in which deposition of deposited particles is blocked by a shielding plate and a portion where a deposited film is not formed is provided. For example, Patent Document 1 discloses a technique related to the limitation of the deposition range at the end of the ear.

  On the other hand, as a polymer film used as a base, various types such as a polyethylene terephthalate (PET) film and a polyethylene naphthalate (PEN) film have been used conventionally. Since the thinning of polymer films has progressed, in order to improve the contact between the thin polymer film and the head, the film has shifted to a film of a high Young's modulus material that can ensure the strength even with a thin film. . As such a high Young's modulus film, an aromatic polyamide (aramid, aromatic PA) film is representative.

  However, the aromatic PA film is superior to the PET film and the PEN film in terms of heat resistance, but has the property that it is very easily charged. Therefore, if there is a portion where the deposited film is not formed at the end of the ear, some electric action, for example, the recoil electrons of the electron beam used for evaporation of the deposition source metal during deposition, the adhesion of secondary electrons, The problem is that only the edge of the ear is charged due to exposure to the plasma space during film surface treatment, protective film formation, etc., which results in poor running (ear end bending). was there. When the roll is wound while the ear end breakage occurs, the ear end breakage portions overlap and are wound, and wrinkles are generated therefrom. Since the wrinkled portion cannot be used as a product, production must be stopped. In this way, when the ear end breaks, the roll cannot be wound for a long time due to the generation of wrinkles, resulting in a significant reduction in manufacturing efficiency.

  As a technique for preventing the occurrence of wrinkles of the base film at the time of vapor deposition, for example, in Patent Document 2, a film having a film thickness smaller than a predetermined film thickness is formed in a short period immediately after the film formation of the magnetic film, and thereafter Furthermore, a method for manufacturing a magnetic recording medium in which film deposition is performed with a predetermined film thickness is described.

JP-A-11-200011 (Claims etc.) JP 2000-285451 A (Claims etc.)

  As described above, in order to realize efficient production of a vapor deposition type medium using aromatic PA, it is necessary to solve the problem of so-called edge bending. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a magnetic recording medium having excellent production efficiency by solving the problem of edge bending caused by charging in the production process of a vapor deposition type medium using an aromatic PA film. There is.

  As a result of intensive studies, the present inventors have formed a deposited film having a predetermined thickness that is thinner than the target film thickness at the end of the ear, thereby preventing the occurrence of charging at the end of the ear and improving manufacturing efficiency. As a result, the present invention has been completed.

  According to the method of manufacturing a magnetic recording medium of the present invention, a metal thin film magnetic layer is formed on a nonmagnetic substrate by vacuum deposition while a long nonmagnetic substrate mainly composed of aromatic PA is run along a cooling drum. In doing so, a plate material is disposed between the nonmagnetic substrate and the vapor deposition source so as to cover at least the widthwise end of the nonmagnetic substrate, and an average film thickness of 5 to 30 nm is formed at the widthwise end. A metal vapor deposition film thinner than the film thickness of the metal thin film magnetic layer is formed.

  The formation area of the metal vapor deposition film is preferably an area having a width of 1 to 3 mm at the end in the width direction.

  By forming a metal vapor deposition film having a predetermined film thickness at the end of the ear according to the present invention, charging at the end of the end of the aromatic PA film can be effectively prevented. It is possible to manufacture an efficient magnetic recording medium that does not occur. Moreover, this metal vapor deposition film can be easily and reliably formed by optimizing the position of the shielding plate in relation to the aromatic PA film.

  The technique described in Patent Document 2 is similar to the present invention in that a film-attached portion having a film thickness smaller than a predetermined film thickness is formed in the magnetic film forming process. In order to prevent the generation of wrinkles at the beginning of the film, a thin film part is formed at the end in the longitudinal direction of the film. In the aromatic PA film, it is not limited to the vapor deposition process. The technical idea is different from the present invention in which the thin film portion is formed at the end in the width direction of the film.

  FIG. 1 shows an example of a vacuum deposition apparatus that can be used in the present invention. The apparatus 100 shown in the figure has a long film-like nonmagnetic substrate 1 from a supply roll 3 in a vacuum chamber 20 that is kept in a vacuum state by being connected to a vacuum pump (not shown) via an exhaust port 21. By carrying out oblique vapor deposition by irradiating the surface of the vapor deposition source metal 9 in the stationary crucible 8 with the electron beam 10A from the electron gun 10 while conveying along the surface of the cooling drum 2 that is fed and rotated, A metal thin film magnetic layer (hereinafter also simply referred to as “magnetic layer”) is formed on the nonmagnetic substrate 1. The vapor deposition angle is determined by adjusting a shielding plate (plate material) 5 disposed between the non-magnetic substrate 1 and the vapor deposition source metal 9, and the shutter 6 that can be opened and closed until the metal melts. Metal adhesion to the magnetic substrate 1 is prevented. Further, from the gas supply device 7, gas is supplied to the vapor deposition metal so as to be uniform in the width direction. The nonmagnetic substrate 1 on which the magnetic layer is formed is then wound around a winding roll 4.

  FIG. 2 shows an enlarged perspective view of the shielding plate 5 shown in FIG. The illustrated shielding plate 5 is a bent plate-like member having an opening 5A for allowing vapor deposition particles to pass through in the center, determines the vapor deposition angle in the traveling direction of the nonmagnetic substrate 1, and defines the vapor deposition region in the width direction. decide. In the present invention, the plate material, in the illustrated example, the shielding plate 5 is separated from the cooling drum more than the position where the end portion in the width direction of the nonmagnetic substrate 1 is completely shielded, and further overlaps with the ear end portion. By arranging to reduce the portion, it is important to form a metal vapor deposition film with a predetermined film thickness at the end in the width direction.

  FIG. 3 shows an explanatory view of the vapor deposition process as seen from the side of the cooling drum 2. As shown in the drawing, the vapor deposition particles jumping out from the vapor deposition source 9 pass through the opening 5 </ b> A of the shielding plate 5 and adhere to the nonmagnetic substrate 1. At this time, vapor deposition particles usually hardly reach the area shielded by the shielding plate 5 at the widthwise end 1a of the nonmagnetic substrate 1, but the distance L between the cooling drum 2 and the shielding plate 5, and By appropriately adjusting the shielding width (overlap width between the nonmagnetic substrate 1 and the shielding plate 5) w of the width direction end portion 1a, the vapor deposition particles wrap around the width direction end portion 1a. In the vicinity thereof, a metal vapor deposition film having a predetermined film thickness smaller than that of the magnetic layer is formed. Therefore, as the plate material according to the present invention, any material can be used as long as it can form a metal vapor deposition film while covering the width direction end portion of the nonmagnetic substrate 1 while blocking vapor deposition particles to some extent. In view of heat resistance and the like, it is preferable to use a metal such as stainless steel. In addition, the shape may be flat or formed from a curve, and the thickness may not be constant. As shown in the figure, the present invention can also be implemented by adjusting the distance between the cooling drum and the shielding plate using a known shielding plate as the plate material.

  Since the metal vapor deposition film at the end of the ear is formed by wrapping around the vapor deposition particles as described above, the film thickness decreases from the center of the nonmagnetic substrate 1 toward the edge. In the present invention, it is necessary to form such a metal vapor deposition film with an average film thickness of about 5 to 30 nm, preferably about 7 to 10 nm. If the average film thickness of the metal vapor deposition film is less than 5 nm, sufficient antistatic effect cannot be obtained, and the ear end breakage cannot be prevented. On the other hand, if the average film thickness exceeds 30 nm, there are too many wraparounds, causing vapor deposition particles to adhere to the cooling drum, resulting in problems such as contamination of the cooling drum and heat loss at the ear ends.

  Here, the formation region of the metal vapor deposition film is usually narrower than the shielding width w. The width of the specific formation region is not particularly limited, but if the ear end portion is widened, the portion that can be used as a product is reduced accordingly, so both the production yield and the contamination prevention of the cooling drum are reduced. From the viewpoint, it is preferable that the region has a width of about 1 to 3 mm at the end in the width direction.

  Further, in order to reliably form the metal vapor deposition film as described above, the shielding plate 5 has, for example, a distance L from the cooling drum 2 of 3 mm or less and a shielding width w of the width direction end portion 1a. , And disposed at a position that is 1 to 2 times the distance L from the cooling drum 2. Although it depends on other conditions, if the distance L between the cooling drum 2 and the shielding plate 5 is larger than this range, the amount of the vapor deposition particles becomes too large, and the cooling drum 2 is contaminated or the ear ends are heat lost. May occur. Further, even when the shielding width w is smaller than the distance L, a problem due to excessive wraparound tends to occur. On the other hand, when the distance L exceeds twice the distance L, the formation of the metal vapor deposition film at the end of the ear is insufficient. Such an antistatic effect may not be sufficiently obtained.

  In the method for producing a magnetic recording medium of the present invention, in the vapor deposition step of forming a metal thin film magnetic layer on a long non-magnetic substrate mainly composed of aromatic PA, a metal vapor deposition film is formed on the end of the ear in accordance with the above conditions. As long as it forms the above, the desired effect of the present invention can be obtained. In the present invention, the details of the production process other than those relating to the metal vapor deposition film and the materials used are not particularly limited, and can be appropriately selected from commonly used materials according to a conventional method. The configuration is as follows.

  As the material of the nonmagnetic substrate, a material mainly composed of aromatic PA is used. In particular, the present invention is effective when using a nonmagnetic substrate made of only aromatic PA. The aromatic PA includes a modified aromatic PA, and the polymer material used in addition to the aromatic PA is not particularly limited, and a commonly used polymer material can be appropriately used. Further, the thickness is appropriately selected depending on the application in which the magnetic recording medium is used. For example, when the magnetic recording medium is used as a data tape, it is selected according to the recording capacity and the system requirement value. Usually, it is 3 to 10 μm. In addition, since the suitable range of the average film thickness and formation area of the said metal vapor deposition film does not depend on the dimension of a nonmagnetic base | substrate, there is no restriction | limiting in particular in the nonmagnetic base | substrate applied in this point.

As the magnetic material of the magnetic layer, pure metals such as Co and Fe, or Co—Ni, Co—Fe, Co—Ni—Fe, Co—Cr, Co—Cu, Co—Ni—Cr, Co—Pt, Alloys such as Co-Pt-Cr, Co-Cr-Ta, Co-Ni-B, Co-Ni-Fe, Co-Fe-B, and Co-Ni-Fe-B can be used. From the viewpoint of electromagnetic conversion characteristics, it is preferable to use Co or Co alloy. Usually, such a magnetic material is deposited directly on the non-magnetic substrate or deposited after Ni is deposited on the non-magnetic substrate to form the magnetic layer. In the vapor deposition of the magnetic layer, the inside of the vapor deposition chamber is evacuated to about 1.33 × 10 ⁻⁴ Pa (10 ⁻⁶ Torr), and then the magnetic material as a vapor deposition source is melted with an electron gun, and the entire magnetic material is melted. At this point, the non-magnetic substrate is caused to travel along the cooling drum, and vapor deposition is started on the cooling drum. At this time, in order to control the magnetic characteristics, an oxidizing gas selected from oxygen, ozone, and nitrous oxide is introduced into the magnetic layer.

On the magnetic layer, a hard film containing carbon as a main component, that is, a so-called DLC film is usually provided for the purpose of preventing deterioration. Here, “consisting mainly of carbon” means that the carbon content in the film is 60 to 80 atomic%, and usually contains hydrogen in addition to carbon. The atomic ratio (H / C) of hydrogen to carbon is preferably in the range of 0.25 to 0.66. Further, the “hard film” specifically means a film having a Vickers hardness of 6370 N / mm ² (650 kg / mm ² ) or more, and the hardness is 1.9 or more in terms of a refractive index. It has been found that a film having such a refractive index can approximate the hardness from the refractive index. For example, the Vickers hardness when the refractive index is 1.9 is 6370 N / mm ² (650 kg / mm ² ). The upper limit of the refractive index is not particularly limited, but is about 2.25, which corresponds to a Vickers hardness of 29400 N / mm ² (3000 kg / mm ² ). As a method of approximating the hardness from the refractive index, the refractive index of a hard film is measured with an ellipsometer, while the Vickers hardness is measured with a micro hardness meter (manufactured by NEC Corporation) to prepare a calibration curve in advance. The hardness can be known from the refractive index. Further, such a hard film forms an amorphous layer or a continuous layer close thereto, and has broad peaks at 1560 cm ⁻¹ and 1330 cm ⁻¹ in Raman spectroscopic analysis. In the present invention, the term “DLC film” is used to mean such a “hard film mainly composed of carbon”. The method for forming the DLC film is not particularly limited, but preferably one of a plasma CVD method, an ionized vapor deposition method, and a sputtering method is used.

  Among these, details of the plasma CVD method are described in, for example, Japanese Patent Laid-Open No. 4-41672. The plasma in the plasma CVD method may be either direct current or alternating current, but it is preferable to use alternating current. When alternating current is used, it can be appropriately used from a few hertz to a microwave band. Further, ECR plasma described in “Diamond Thin Film Technology” (published by General Technology Center) can also be used.

When the DLC film is formed by a plasma CVD method, it is preferable to use a compound containing C and H as the source gas, but a compound containing C and a compound containing H can also be used together. Examples of the compound containing both C and H include, for example, hydrocarbons such as CH ₄ , C ₂ H ₄ , C ₂ H ₆ , C ₃ H ₈ , C ₆ H _6, etc. Examples of the compound in which CO, CO _{2 and the} like contain H include H ₂ , H ₂ O, NH _{3 and the} like. Further, a compound containing neither C nor H, for example, a compound represented by NO _x such as NO, NO ₂ , N ₂ O, N ₂ or the like may be used in combination as necessary.

  What is necessary is just to determine suitably the flow volume of source gas at the time of performing plasma CVD according to the kind of source gas. The operating pressure is usually 1.33 to 66.5 Pa (0.01 to 0.5 Torr).

  After the formation of the DLC film, it is preferable to perform a surface activation treatment with plasma in order to increase the affinity between the film surface and the lubricant. This post-treatment is preferably performed using oxygen or a gas containing oxygen. For example, oxygen, air, carbon dioxide gas, or the like can be used. As a post-treatment method, it is practical and preferable to use the same method as described above when forming the DLC film. The frequency in the post-processing is preferably about 1 kHz to 40 MHz similar to that at the time of the DLC film formation, and the effect is easily manifested particularly in the range of 50 kHz to 13.56 MHz.

A lubricant layer is provided on the DLC film in order to reduce the friction coefficient during running. As the lubricant component of the lubricant layer, a lubricant containing a fluororesin, a hydrocarbon ester, or a mixture thereof can be used. Specifically, for example, a basic structure includes a structure represented by R ¹ —A—R ² . here,
R ^{1 is} CF ₃ (CF ₂ ) _n- , CF ₃ (CF ₂ ) _n (CH ₂ ) _m- , CH ₃ (CH ₂ ) _p- , or H;
A: -COO -, - O-, or _{COOCH (C p H 2p + 1} ) CH 2 is COO-,
_{^{R 2: CF 3 (CF 2}} ) n -, CF 3 (CF 2) n (CH 2) m -, CH 3 (CH 2) p -, or H. However, unlike R ¹ and R ² , those satisfying n = 7 to 17, m = 1 to 3, and p = 7 to 30 are preferable. Further, if R ¹ and / or R ² are linear, the lubricating effect is large. If n is smaller than 7, the water repellent effect is low, and if n is larger than 17, the blocking phenomenon between the lubricant and the nonmagnetic substrate or the back coat layer occurs, and the friction is not lowered. Among these, a lubricant containing fluorine is particularly preferable. Further, two or more of these lubricants may be mixed and used.

  These lubricant components are dissolved in a solvent such as ketones, hydrocarbons, and alcohols to prepare a lubricant coating solution. Examples of ketones include acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, cyclohexanone, and diethyl ketone. Examples of hydrocarbons include normal systems such as hexane, heptane, octane, nonane, decane, andecane, and dodecane, and iso-systems. Examples of alcohols include methanol, ethanol, propanol, isopropanol and the like. A lubricant layer can be formed by applying the prepared lubricant coating solution on the DLC film and drying it. The thickness of the lubricant layer is about several nm. The amount of the lubricant component can be adjusted by the concentration of the coating solution.

  Furthermore, in the present invention, an S / N characteristic can be improved by providing an underlayer between the magnetic layer and the nonmagnetic substrate as desired. The underlayer is a nonmagnetic or non-magnetic layer and can be formed by increasing the amount of oxygen introduced relative to the film thickness in the same manner as the magnetic layer. Specific film formation conditions for the underlayer, for example, the transport speed of the nonmagnetic substrate during film formation, the amount of introduced oxygen, and the like can be appropriately determined according to common usage, and are not particularly limited. In particular, as the supply gas at the time of film formation, it is preferable to use not only oxygen but also a gas containing at least one of inert gas such as Ar and nitrogen in oxygen. Can be further improved. This is because the presence of the inert gas causes the underlayer to grow in the form of particles and the micro unevenness increases, so that the magnetic layer grown on the underlayer is more strongly oriented in the film plane and the coercive force is increased. This is thought to be caused by this.

  A back coat layer can be provided on the surface of the nonmagnetic substrate opposite to the magnetic layer and DLC film formation surface. The back coat layer is formed by applying a coating material for a back coat layer in which a binder resin and an inorganic compound and / or carbon black are mixed and dispersed in an organic solvent to the surface of the substrate opposite to the magnetic layer, Any coating composition may be used as long as it is used for this type of magnetic recording medium. For example, the binder resin is a vinyl chloride copolymer, polyurethane resin, acrylic resin, epoxy resin, phenoxy resin, polyester resin, etc., and these may be selected appropriately according to the characteristics of the medium and process conditions. Can be used. Examples of the carbon black include furnace carbon black and thermal carbon black. Examples of the inorganic compound include calcium carbonate, alumina, and α-iron oxide. The particle size of these particles may be appropriately selected from the electrical resistance and friction characteristics required for the medium. As the organic solvent, ketone-based or aromatic hydrocarbon-based, for example, methyl ethyl ketone, toluene, cyclohexanone, or the like can be used, and may be appropriately selected in consideration of the solubility of the binder resin to be used. The thickness of the back coat layer is preferably 0.1 to 0.7 μm, particularly preferably 0.3 to 0.5 μm.

Examples 1-4 and Comparative Examples 1-5
On one side of a non-magnetic substrate (made by Toray Industries, Inc.) of a modified aromatic PA (aramid) having a thickness of 4.0 μm, 100% Co is introduced at a film thickness of 80 nm while introducing oxygen by vapor deposition. A layer was formed to form a magnetic layer. In vapor deposition, the vacuum vapor deposition apparatus shown in FIG. 1 was used with the distance L between the cooling drum 2 and the shielding plate 5 and the shielding width w set as shown in Table 1 below. The obtained magnetic layer had Mr · t = 28 mA (2.8 memu / cm ² , Mr: residual magnetization, t: thickness of the magnetic layer), and Hc = 119.4 kA / m (1500 Oe).

The film thickness of the metal vapor deposition film formed on the edge part of the nonmagnetic substrate after vapor deposition was calculated from the cross-sectional TEM (transmission electron microscope) image and the measured value of Co amount by fluorescent X-rays. Specifically, first, in the vicinity of the end of the ear, the boundary portion (the portion on the width direction end side of the non-magnetic substrate from this boundary is visually different from the portion used as the product (the portion having a film thickness of 80 nm). Were cut with a cutter, and the edge pieces cut every 50 mm were arranged to be 30 mm. These were arranged in a φ30 mm sample holder, and the amount of Co was measured by fluorescent X-rays using the following apparatus.
Device name: RIX2000 (manufactured by Rigaku Corporation)
Measurement conditions: Sample diameter 30 mm diameter, X-ray output Rh tube 50 kV-50 mA, detection X-ray Co-Kα, spectral crystal LIF1, peak measurement 40 seconds, back measurement 2 points (each 10 seconds)

  Next, the film thickness was obtained from the obtained Co amount measured value using a calibration curve obtained in advance from the relationship between the actually measured value by cross-sectional TEM image observation and the Co amount measured value by fluorescent X-ray. Furthermore, since the film thickness of the edge part is different in the width direction, the average value of the film thickness obtained by the above measurement was determined and this was used as the average film thickness.

Next, a DLC film having a thickness of 0.01 μm was formed on the magnetic layer under the following conditions. The presence or absence of bending of the edge edge during the DLC film formation was confirmed for the 20 rolls of the non-magnetic substrate on which the magnetic layer was formed under the same conditions. The case where 1 or 2 rolls were generated was evaluated as Δ, and the case where there were 3 rolls or more was evaluated as x. These results are also shown in Table 1 below.
(DLC film deposition method): Plasma CVD method (RF)
(Ion source): Ethylene gas (gas flow rate): 10 sccm
(Discharge frequency): 50 kHz

Next, in order to increase the affinity of the film surface for the lubricant, the DLC film was post-treated with plasma using oxygen gas. Thereafter, a lubricant coating solution was applied on the post-treated DLC film by a die nozzle method and dried to form a lubricant layer. Lubricant coating liquid was prepared by mixing a fluorine-containing compound of a succinic acid derivative and a fluorine-containing compound of an aliphatic ester as lubricant components shown below in a mixed solvent of MEK / hexane / ethanol = 1/2/7 with the same weight. The total concentration of the lubricant was 0.5% by weight.
(Lubricant component):
_{HOOCCH (C 18 H 37) CH} 2 COOCH 2 CH 2 (CF 2) 7 CF 3
CH ₃ (C ₁₂ H ₂₄ ) COOCH ₂ CH ₂ (CF ₂ ) ₇ CF ₃

Next, on the other surface of the nonmagnetic substrate, a backcoat layer dispersion having the following composition was applied by a die nozzle method so that the thickness after drying was 0.4 μm and dried to form a backcoat layer. The magnetic tape as a magnetic recording medium was manufactured.
(Backcoat layer composition)
Carbon black (particle size 80 nm) 10 parts by weight Carbon black (particle size 20 nm) 40 parts by weight Calcium carbonate (particle size 70 nm) 50 parts by weight Nitrocellulose (Nc) (BTH1 / 2S manufactured by Asahi Kasei Corporation) 40 parts by weight polyurethane Resin (UR-8300 manufactured by Toyobo Co., Ltd.) 60 parts by weight MEK 800 parts by weight Toluene 640 parts by weight Cyclohexanone 160 parts by weight Polyisocyanate (solid content 50%) (Nihon Polyurethane Industry Co., Ltd. Coronate L) 40 parts by weight

  As described above, according to the present invention, the problem of edge-end bending caused by charging in the process of manufacturing a vapor deposition type medium using an aromatic PA film is eliminated, and a magnetic recording medium is efficiently manufactured. It becomes possible.

It is a schematic diagram which shows an example of a vacuum evaporation system. It is a schematic perspective view which takes out and shows the shielding board in FIG. It is explanatory drawing of the vapor deposition process seen from the side of the cooling drum.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nonmagnetic base | substrate 1a Width direction edge 2 Cooling drum 3 Supply roll 4 Winding roll 5 Shielding board (plate material)
5A Opening 6 Shutter 7 Gas supply device 8 Crucible 9 Deposition source metal 10 Electron gun 10A Electron beam 20 Vacuum chamber 21 Exhaust port 100 Vacuum deposition device

Claims (2)

When a metal thin film magnetic layer is formed on a nonmagnetic substrate by vacuum deposition while running a long nonmagnetic substrate mainly composed of an aromatic polyamide along a cooling drum, the nonmagnetic substrate, a deposition source, A plate material is disposed so as to cover at least the widthwise end of the non-magnetic substrate, and at the widthwise end, an average film thickness of 5 to 30 nm is thinner than the film thickness of the metal thin film magnetic layer. A method of manufacturing a magnetic recording medium, comprising forming a metal vapor deposition film. The manufacturing method of Claim 1 which forms the said metal vapor deposition film in the said width direction edge part by width 1-3mm.

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