JP2589185B2 - Manufacturing method of magnetic recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a magnetic recording medium for removing dust in a manufacturing process of a magnetic recording medium, and more particularly, to removing dust attached to a calendar roll of a calendar processing apparatus. How to do it.

(Prior Art) In general, in a manufacturing process of a magnetic recording medium, in order to improve the surface smoothness of the medium, the medium is sandwiched by a plurality of pairs of opposed calender rolls to perform a calendering process. The surface of the calendar roll is formed to have high smoothness, whereby the recording medium surface after the calendar processing is given high smoothness.

However, if the calendar processing is performed with the dust adhered to the surface of the recording medium or the surface of the calendar roll, the dust is caught between the surface of the recording medium and the surface of the calendar roll, thereby damaging the surface of the recording medium and impairing the smoothness. It is. Therefore, it is necessary to remove the dust.

As a conventional technique for removing such dust, in a device for vacuum-depositing a ferromagnetic metal on the surface of a running nonmagnetic support, dust is removed at a predetermined position in a vacuum chamber where the ferromagnetic metal can contact the surface of the nonmagnetic support. A roll is arranged so that dust adhering to the non-magnetic support can be turned to the dust removing roll before the non-magnetic support is rolled into the cooling can (hereinafter, referred to as a roll).
Conventional technology 1) is known (Japanese Utility Model Application Laid-Open No. 60-5691).
No. 7). Further, in a calendar processing apparatus, there is known a technique (hereinafter, referred to as Conventional Technique 2) in which dust adhered to a calendar roll is scraped off by a doctor knife disposed near the calendar roll (see, for example, Japanese Unexamined Patent Publication (Kokai) No. 2000-115). No. 62-88799, Japanese Utility Model Publication No. 62-23838, etc.). However, the prior art 1 removes dust adhering to the surface of the non-magnetic support at the position before the non-magnetic support is caught in the cooling can. The dust attached to the surface and the dust directly attached to the cooling can cannot be removed. Further, according to the prior art 2, if the clearance between the calendar roll and the doctor knife changes, the surface of the calendar roll may be damaged by the doctor knife. It is sprayed on.

As a technique for solving the problems of the prior arts 1 and 2, as an apparatus for vacuum-depositing a ferromagnetic material on a non-magnetic support, an adhesive is formed on the circumference of a cooling can around which the non-magnetic support is wound. There is known an apparatus in which a roll having a roll is contacted to remove dust adhering to the surface of the cooling can (hereinafter, referred to as prior art 3) (Japanese Patent Laid-Open No. Sho 62-62).
No. 17176).

(Problems to be Solved by the Invention) However, in the above-mentioned prior art 3, no consideration is given to the surface roughness of the adhesive roll and the cooling can. That is, the present inventors have discovered that the above-described dust-removing effect is significantly reduced as the surface roughness of the adhesive roll is increased. However, such a phenomenon is not considered in the above-described related art 3. However, since the surface roughness of the pressure-sensitive adhesive roll is not properly set based on the measurement result of the above phenomenon, the dust removal efficiency may be lower than when no pressure-sensitive adhesive roll is provided.

(Means for Solving the Problems) The method for producing a magnetic recording medium according to the present invention is directed to a pressure-sensitive adhesive roll having a surface roughness defined by the following formula on a circumferential surface of a calendar roll that is not in contact with the magnetic recording medium. Are brought into contact with each other to perform a calendar process.

Ra (N) ≦ 1000 Ra (R) (where Ra (N) is the surface roughness of the adhesive roll, Ra
(R) is the surface roughness of the calendar roll. (Function) By setting the surface roughness of the pressure-sensitive adhesive roll to be in contact with the calendar roll to a predetermined value or less, the effective contact area with the calendar roll can be set to a predetermined value or more. In addition, the generation of dust due to the scraping of the protrusions on the surface of the adhesive roll can be reduced to a predetermined value or less.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing, in the form of a side view, a roll arrangement of a calendar device suitable for carrying out a method of manufacturing a magnetic recording medium according to the present invention. In FIG. 1, M indicates a metal roll, and E indicates an elastic roll.

A calendar device suitable for carrying out the method of the present invention includes, for example, as schematically shown in FIG. 1, metal rolls M1, 2, 3, 4
And the elastic rolls E1, 2, and 3 are arranged alternately, and the rotation axes of all the rolls are parallel to each other.
Let them pass between these calendar rolls M1,2,3,4 and E1,2,3 so as to form an S-shaped curve, and the above-mentioned calendar rolls M1,2,3,4, E1,2,3 The adhesive roll 2 is configured to be rotated in contact with the circumferential surface where the magnetic recording medium 1 is not in contact.

In the calendar device shown in FIG. 1, the magnetic recording medium 1 is arranged such that the support layer 3 faces upward in FIG. 1 and the magnetic recording layer 4 faces downward in FIG. Then, while traveling between the calender rolls M1, 2, 3, 4, and E1, 2, 3, an appropriate calendering process is performed, and the surface thereof has high smoothness. However, dust adheres to the calendar rolls M1,2,3,4 and E1,2,3, and the dust is deposited on the calendar rolls M1,2,3,4, E1,2,3 and the magnetic recording medium 1. The surface of the magnetic recording medium 1 will be scratched and the surface smoothness will be impaired if it is sandwiched between them. Therefore, each of the calendar rolls M1,2,3,4 and E1,2,3 has the adhesive Roll 2 is abutted, and these calendar rolls M1, 2, 3, 4, E1,
Dust adhering to 2 and 3 is transferred to the adhesive roll 2.

By the way, in such an adhesive roll 2, if the surface roughness is too large, the calender rolls M1, 2, 3, 4, E
There is a problem that the effective contact area with 1, 2, and 3 decreases, and the dust removing effect decreases with a decrease in the adhesive force, and further, the amount of dust increases due to the shaving of the convex portion on the surface of the adhesive roll 2, The surface roughness Ra (N) of the adhesive roll 2 is set to be equal to or less than a predetermined value. That is, when the surface roughness of the calendar rolls M1,2,2,4 and E1,2,3 is Ra (R), the value is set to satisfy the conditional expression of Ra (N) ≦ 1000Ra (R). ing. Preferably, Ra (N) ≦ 50
0Ra (R), more preferably Ra (N) ≦ 100Ra (R). In addition, the calendar rolls M1,2,3,
4. The surface roughness Ra (R) of E1,2,3 is usually 0.002-0.00.
It is adjusted to 7 μm (cutoff value: 0.25 mm). Further, as the surface material of the pressure-sensitive adhesive roll 2, it is possible to use polyurethane rubber, silicon rubber, nitrile rubber, and various materials to which dust can be transferred, such as hypalon rubber, EPDM rubber, and nylon.

Note that the arrangement of the calendar rolls in the calendar device is not limited to the arrangement in which the rolls are in parallel and sequentially contact each other as shown in FIG. 1. For example, as shown in FIG. The arrangement may be such that performed by a set of independent calendar rolls M5,6, E4, M7, again in this case each calendar roll
Adhesive rolls 2 are provided so as to be in contact with M5, 6, E4, and M7. In FIG. 2, M5 and M6 are both metal rolls, and E4 and M7 are an elastic roll and a metal roll, respectively.

The above-described calendering in the calendar device is preferably performed at a linear pressure of 250 kg / cm or more, and more preferably at a linear pressure of 300 kg / cm or more. It is desirable that the metal roll be maintained at a temperature of 40 ° C. or higher. However, since the metal roll involved in the execution of the final calendar step also functions as a cooling roll, it is not usually heated.

Next, in the calendar device shown in FIG. 1, the surface roughness Ra (N) of the adhesive roll 2 was measured using the calendar rolls M1, 2, 3, 4, E
The surface roughness Ra (R) of 1, 2, and 3 is changed in a range of 2 to 2000 times, and a predetermined calendar process is performed on the magnetic recording medium 1 every time the change is made. A plurality of 3.5-inch floppy disks were manufactured from each of the magnetic recording media 1 thus obtained, and a dropout test was performed on each of the floppy disks to calculate the NG ratio. The results are shown in the graph of FIG. Was.

The width of the adhesive roll 2 was set to 50 cm.
The pressure per cm was set to about 0.2 kg / cm. As a floppy disk drive device, Sony 3.5
An inch disk drive (MP-F17W) was used, and the dropout test conditions were as follows.

Recording linear density: 686 cycles / mm Track width: 115 μm Slice level: 70% Drop-out inspection is performed on all tracks on the floppy disk, and if even one drop-out is detected, the floppy disk is treated as an NG product I decided that. The horizontal axis of the graph shown in FIG. 3 is Ra (N) / Ra
The value P of (R) and the vertical axis indicate the value Q of the NG rate when the NG rate when the adhesive roll 2 is not provided at all is 1.

According to the graph shown in FIG. 3, when P becomes 100 or more, Q sharply increases. That is, the NG rate sharply increases. When P is about 2000, the NG rate is almost the same as when no adhesive roll is used. Therefore, the surface roughness Ra (N) of the adhesive roll is the surface roughness Ra of the calendar roll.
(R) should be about 2000 times or less, and should be 1000 times or less in consideration of the safety factor, and preferably 50 times or less.
0 times or less (Q is 0.5 or less), more preferably 100 times or less (Q is 0.2 or less).

(Effects of the Invention) As described above, according to the method for manufacturing a magnetic recording medium of the present invention, the surface roughness of the adhesive roll is set to a predetermined value or less, and the effective contact area with the calendar roll is set to a predetermined value or more. Since the generation of dust due to the scraping of the convex portion of the surface of the adhesive roll is set to a predetermined value or less, it is possible to reduce the scratches on the surface of the magnetic recording medium due to the dust when the calendar processing is performed. As a result, it becomes possible to manufacture a magnetic recording medium with a low dropout occurrence rate.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing an apparatus for carrying out the method of the embodiment of the present invention, FIG. 2 is a side view schematically showing a modification of the apparatus shown in FIG. 1, and FIG. 4 is a graph illustrating that the yield of a magnetic recording medium manufactured by a method according to an embodiment of the present invention is affected by the surface roughness of an adhesive roll. M1,2,3,4,5,6,7 ... Metal roll (Calendar roll) E1,2,3,4 ... Elastic roll (Calendar roll) 1 ... Magnetic recording medium 2 ... Adhesive roll

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hideo Yamanaka 2-2-1-1, Ogimachi, Odawara-shi, Kanagawa Prefecture Inside Fuji Photo Film Co., Ltd. (56) References JP-A-62-17176 (JP, A) Sho Akai 60-56917 (JP, U) JP-A 62-88799 (JP, U) JP-A 62-23838 (JP, Y2)

Claims (1)

(57) [Claims] 1. A method of manufacturing a magnetic recording medium, comprising: rotating two calendar rolls facing each other, and running the magnetic recording medium while holding the magnetic recording medium between the two calendar rolls, and performing a calendar process on the surface of the magnetic recording medium. A method for manufacturing a magnetic recording medium, comprising: bringing a pressure-sensitive adhesive roll having the following surface roughness into contact with a circumferential surface of a calendar roll that is not in contact with the magnetic recording medium, and performing a calendaring process. Ra (N) ≦ 1000 Ra (R) (where Ra (N) is the surface roughness of the adhesive roll, Ra
(R) is the surface roughness of the calendar roll)