JPH01312731A - Calender roll cleaning method for magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the productivity by applying calender processing to a magnetic recording medium having a magnetic layer and applying calender processing to a web without any magnetic layer. CONSTITUTION:A magnetic recording medium is passed between plural metallic rolls and elastic rolls and its magnetic substance layer is subjected to mirror surface processing at a temperature under pressure, then uncoated part (b) of a support 10A is used as a cleaning web to apply calender processing before soiling starts transposition of press scratch onto the magnetic layer 10B in at least one of metallic rolls 1, 2, 3 during the calender processing of the part (a) of the magnetic tape 10 having the magnetic layer 10B on the supporting body 10A. Then the contamination on the metallic rolls 1, 2, 3 is pressed onto the base 10A to remove the contamination on the metallic rolls 1, 2, 3 and then calender processing having a part (c) with the magnetic substance layer 11B is applied. Thus, the cleaning of the metallic rolls 1, 2, 3 is executed without stopping the manufacture line and the productivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for cleaning metal rolls of a calendering device for magnetic recording media.

[Conventional technology]

In magnetic recording media, in order to obtain surface smoothness,
Alternatively, in order to increase the packing density of the magnetic layer, calendering is generally performed.

In this calendering process, metal rolls with mirror-finished surfaces and elastic rolls are usually arranged alternately, and the magnetic recording medium is passed through it in an S-shape with the side of the magnetic layer corresponding to the surface of the metal roll, and the temperature is increased. The magnetic layer is made to have a mirror surface by applying pressure.

However, as the calendering equipment continues to operate for a long period of time, the surface of the metal roll becomes damaged and the frictional force between the surface of the metal roll and the magnetic layer increases, causing stains to which the magnetic layer forming material adheres. is transferred to the magnetic layer, causing dropouts in the magnetic recording tape.

Conventionally, in order to avoid such a situation, the metal rolls were periodically cleaned by manually removing dirt. However, with this manual cleaning method, the production line must be temporarily stopped until cleaning is completed, resulting in a decrease in productivity.

On the other hand, in Japanese Patent Application Laid-Open No. 50-105903,
A method using a roll cleaner is disclosed in Japanese Patent Application Laid-Open No. 115240/1983, and a method of spraying a release gas onto the surface of a metal roll is disclosed in Japanese Patent Application Laid-open No. 165929/1989 to delay staining of the roll surface. disclose a method of coating the surface of a metal roll with a fluorine-based polymer.

[Problem to be solved by the invention]

While the techniques described in each of the above-mentioned publications are effective for improving productivity, the method using a roll cleaner not only increases the cost of the equipment, but also requires the roll cleaner to physically come into contact with the surface of the metal roll. This may cause scratches on the surface of the metal roll. Furthermore, the method of spraying a mold release gas increases production costs and is not practical. Furthermore, in the method of coating the surface of a metal roll with fluorine-based polymer, the surface must be re-polished after coating, which increases the cost, and the coating layer does not have high strength against the metal, so scratches occur more frequently. is high.

Therefore, the main object of the present invention is to provide a processing method that increases productivity.

[Means to solve the problem]

The above problem is to pass a magnetic recording medium between a plurality of metal rolls and an elastic roll to make the magnetic layer mirror-finished by applying temperature and pressure; After calendering the magnetic recording medium having the magnetic layer,
This problem can be solved by calendering a web that does not have a magnetic layer.

[Effect]

After calendering the magnetic recording medium to a point where it is predicted that dirt on the metal roll will remain as a scratch-like transfer to the magnetic layer, a web without a magnetic layer, such as a support for the medium, is calendered. When calendering is performed, dirt adhering to the surface of the metal roll is pressed against the support side and removed from the metal roll. Therefore, when the magnetic layer of the magnetic recording medium is calendered again after that, the calendering process can be performed using the cleaned metal roll, and deterioration of recording and reproducing characteristics such as dropout can be prevented.

For example, in the coating process in which a magnetic layer is coated on a support, by providing an uncoated area in the web where the magnetic layer is not coated, cleaning can be performed in a continuous work process without stopping the calender device. , it greatly contributes to productivity improvement, and is practical because cleaning equipment is not required.

[Specific structure of the invention]

The present invention will be explained in more detail below.

Figure 2 shows an overview of the calendar processing device.
This is an example of a stage calender processing device.

The metal rolls 1, 2.3 and the elastic rolls 4, 5 are arranged alternately with parallel axes. Each metal roll 1, 2.
3, the surface of the roll steel is coated with chrome plating to give it a mirror finish.

The elastic rolls 2 and 4 have cotton, nylon, or the like on their surfaces. 6 is a guide roll.

In such a calendering device, pressure and heat are applied to the 6n layer in the process of passing the magnetic recording medium M in an S-shape with the magnetic layer facing the surface of the metal roll 1.
A smoothness corresponding to the metal roll 1.2.3 is provided.

Each metal roll 1, 2.3 has a built-in heating mechanism using a heat medium or an induction heating mechanism.
The surface is heated and the heat is applied to the magnetic layer along with pressure to contribute to smoothing.

In the present invention, as shown in FIG. 1A, during calendering of part (a) of a magnetic tape IO having a magnetic layer 10B on a support 10A, at least one of the metal rolls 1.2.3 is contaminated. Before it begins to be transferred in the form of pressure marks to the magnetic layer, the uncoated portion of the support 10A (BL) is calendered as a cleaning web to press the dirt on the metal roll to the support side and remove the dirt on the metal roll. remove,
Subsequently, the portion (C) having the magnetic layer is calendered.

In this case, in order to avoid damaging the metal roll, it is preferable to
It is desirable to open the calender nip once when passing through the calender in section f). By the way, the cleaning web for the metal roll may be made of a material other than the support of the magnetic recording medium. In this case, as shown in FIG. 1B, the magnetic tape 10.degree. 11 is connected to the cleaning web 12 by adhesive tape or the like. Dirt can be suitably removed by using a cleaning web that is not smooth but has been treated to be matte, at least within a range that does not damage the surface of the metal roll.

The calendering length of the cleaning web or support is 2 to 200 times the outer circumference of the metal roll, especially 2 to 5 times the outer circumference of the metal roll.
Preferably, the length is 0 times. If the cleaning effect is less than 2 times, the cleaning effect will be small, and if it exceeds 200 times, the cost of the uncoated portion of the support will become a large proportion of the product cost (and the dust or support that will be brought into the calender device due to the charge on the support) will increase. This may cause contamination of the elastic roll by oligomers, etc.

The timing to start cleaning naturally depends on the degree of dirt on the metal roll, but it is usually between 9000 and 5000.
It is desirable to perform this after 0 m calendering.

During cleaning, it is desirable to apply pressure and heat to the support in the same way as during calendering.
It may be higher than ~500 kg/cm.

〔Example〕

Next, examples will be shown.

As the cleaning web, the same PET film as the magnetic tape support (surface roughness Ra-0, 025 μm) was used.
Calendering was carried out using a calendering device as shown in Fig. 2 at a metal roll temperature of 75°C, a linear pressure of 200 kg/cm, and a processing speed of 200 m/1 lin. In this case, if a magnetic tape is manufactured by calendering 50 m of uncoated support every 9000 m of magnetic tape processing, the occurrence of dropouts due to stain transfer usually increases after about 15,000 m. However, no increase in the occurrence of dropouts was observed up to approximately 100,000 m. FIG. 3 shows the number of dropouts for each processing length. Comparative Example 1 is a case in which calender treatment was performed under all the same conditions as in the example except that the uncoated area was not calendered. Drop Ala I recorded and reproduced a predetermined signal on the videotape obtained with each processing meter, and measured the number of cases in which the reproduction output continued to differ by 16 dBi by 5 μ96 C or more for 10 minutes, and expressed the average per minute.

〔Effect of the invention〕

As described above, according to the present invention, metal roll cleaning can be carried out without substantially stopping the production line.
Productivity increases dramatically.

[Brief explanation of the drawing]

Figures 1A and 1B are schematic diagrams showing aspects of a clean web for cleaning, Figure 2 is a schematic diagram of a calender processing device, and Figure 3 is a diagram showing the number of dropouts for each processing length of the obtained magnetic recording medium. It is a graph. 1.2.3... Metal roll, 4.5... Elastic roll, 10.11... Magnetic tape, Work 2... Clean web, 13... Adhesive tape. Figure 1A Figure 2

Claims (1)

[Claims] (1) When passing a magnetic recording medium between a plurality of metal rolls and an elastic roll to mirror-finish the magnetic layer; After calendering a magnetic recording medium formed by coating a magnetic layer on a non-magnetic support, A method for cleaning a calendar roll of a magnetic recording medium, which comprises calendering a web having no magnetic layer.