JPS5992439A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain sufficient surface lubricity and to enable the reduction of an initial cost by applying a magnetic coating on a flexible substrate and drying the same then sandwiching the substrate between a metallic roll and a glass roll and subjecting the substrate in a pressurized and heated state to a super calender treatment. CONSTITUTION:One nip of super calender is constituted of a metallic roll which is produced by subjecting a carbon steel pipe for structural purpose to hard chrome plating and finishing the surace by mechanical polishing and is 0.05mum in the average surface roughness measured by using ''Tallystep'' produced by Ranktaylor Hobson Co. and a glass roll which is produced by forming glass into a roll shape and finishing the surface by polishing and is 0.05mum in average surface roughness. A magnetic recording medium which is subjected to coating and drying in an ordinary stage is sandwiched between said rolls and is treated under the conditions of 80 deg.C, 150kg/cm<2> linear pressure and 50m/min speed, and the medium treated in such a way is slit to 1/2 inch width, whereby a magnetic tape is obtd. Substantially surface smoothness is thus obtd. and a color S/N is improved even if the tape is treated by one nip.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing magnetic recording media such as magnetic tapes and magnetic sheets used in audio and video equipment, computers, etc.Constitution of conventional examples and problems thereof Magnetic recording media include magnetic tapes, magnetic sheets, and other flexible supports coated with magnetic paint, and these media have been used for audio, video, and computer applications, and have recently become popular. Development can be seen.

In particular, with the recent spread of home video, the demand for videotapes has increased significantly. Although it depends on how the videotape is used, it is desired to improve the electromagnetic conversion characteristics by recording for a long time and converting the audio to stereo.
Although efforts have been made to improve the constituent materials and manufacturing techniques, the current situation is that they have not yet reached a fully satisfactory level.

Magnetic tape is manufactured through approximately the following steps.

(1) A manufacturing process for magnetic paint, in which magnetic powder, binder, and various additives added as necessary are mixed and dispersed in an organic solvent. (2) Magnetic paint is applied to a flexible support such as polyester film. (3) A surface forming process in which the coated magnetic film is heated and pressurized to make the surface smooth; (4) The surface-formed magnetic film is processed into a predetermined size and shape according to the purpose. (6) Assembling process to finish M products In the above manufacturing method, especially when manufacturing magnetic tapes for video, each process requires more difficult technology than ever due to product characteristics. It has been demanded.

The following method is well known as a method for improving electromagnetic conversion characteristics mainly based on the signal-to-noise ratio (hereinafter referred to as 8/N).

(1) Magnetic powder is uniformly and densely dispersed in the magnetic layer.

(2) Reduce the particle size of magnetic powder. However, as long as it does not become superparamagnetic.

(3) Improve the smoothness of the magnetic layer surface and reduce spacing loss with the magnetic head.

The present invention particularly relates to (3) among these,
This is commonly referred to as supercalendaring.

Conventionally, supercalendering involves sandwiching a magnetic recording medium such as a magnetic tape between a metal roll and an elastic roll, heating it,
It is carried out under pressure. Elastic rolls, such as cotton rolls, urethane rolls, and nylon rolls, are known. However, with elastic rolls, uneven hardness occurs due to the manufacturing method, which causes pressure unevenness when pressurized, which causes damage to the surface of the magnetic recording medium. It appears as unevenness on the surface. Unfortunately, these irregularities cause spacing loss and tend to deteriorate the electromagnetic conversion characteristics of the tape. In addition, urethane roll
Rolls made of resin, such as nylon rolls, are difficult to polish on the surface, leaving bite marks and polishing streaks, which cause unevenness on the surface of the magnetic recording medium during supercalendering. In addition, rolls made of the above-mentioned resins have the disadvantage that they are deformed by pressure, causing pressure unevenness, and that pressure unevenness is likely to occur due to changes in the hardness of the resin due to heating. Moreover, rolls made of resin suffer from deterioration due to repeated heating and pressurization as described above, making it necessary to replace the resin, which greatly limits their lifespan.

Therefore, in order to obtain a magnetic recording medium with good surface smoothness, it is necessary that the rolls used have good surface properties, have uniform hardness, and have long lifespans and excellent durability. Become.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for manufacturing a magnetic recording medium that can provide sufficient surface smoothness and can significantly reduce equipment costs.

Structure of the Invention The method for producing a magnetic recording medium of the present invention involves applying a magnetic paint to a flexible support, drying it, and then sandwiching it between a metal roll and a glass roll, and superimposing it under pressure and heat. Calendar treatment is performed, and a magnetic recording medium with good electromagnetic conversion characteristics can be obtained.

DESCRIPTION OF EMBODIMENTS Examples of the present invention will be specifically described below. 0 Structural carbon steel pipes were plated with hard chrome, finished by mechanical polishing, and the average surface roughness was measured using a Talistesop manufactured by Rank Taylor Hobson. Surface roughness is 0.0
A 1-nip supercalender was constructed with a 5 μm metal roll and a glass roll whose average surface roughness was 0.05 μm, which was formed by molding glass into a roll and finishing by surface polishing. A magnetic recording medium that has been coated and dried in the usual process is placed between the plates at a temperature of 80°C, a linear pressure of 160 kg/ca, and a speed of SO.
The tape processed under the conditions of m/min was slit into 1/2 inch width to obtain a magnetic tape.

As a comparative example, instead of the opposing glass roll, a roll made of nylon resin was finished by mechanical polishing, and the average surface roughness measured using Talystep was 0.6 μm, and the elastic roll was used. This was installed between metal rolls to form a 5-stage super calender. A magnetic recording medium obtained in the same manner as in the example was sandwiched so that the magnetic layer surface was in contact with a metal roll, and treated under the same conditions of temperature, linear pressure, and speed as in the example to obtain a 1/2 inch width. The magnetic tape obtained by slitting the magnetic tape was put into a video tape recorder (N made by Matsushita Electric Industrial Co., Ltd.).
V-8800), record a specified color signal (-color chroma signal) with a television signal generator, play it back, measure the color S/N with a video color noise meter, and compare the results with the surface of the magnetic layer. Roughness is ranked by Taylor Hoven's Talis tip (LPF; 26H).
The results measured in z) are shown in the following table.

As is clear from the results in the table, it was found that in the case of using a metal roll and a glass roll, sufficient surface smoothness was obtained despite the use of one nip, and the color S/N was also improved.

Details of the invention As explained above, according to the present invention, the conventional method is not obtained.

This makes it possible to obtain a high-performance magnetic recording medium that is less susceptible to deformation, and furthermore, since there is almost no deformation during nipping, which is a problem with elastic rolls, the life of the rolls is dramatically improved. Furthermore, since the one-nip configuration can achieve performance comparable to the conventional 6- to 7-stage configuration, it not only makes the equipment more compact, reduces the number of rolls, and simplifies maintenance and inspection, but also eliminates the major drawbacks of elastic rolls. There is no need for regrinding, etc., making it possible to significantly reduce equipment costs.

Claims (1)

[Claims] Manufacture of a magnetic recording medium characterized by applying a magnetic paint to a flexible support, drying it, and then sandwiching it between a metal roll and a glass roll and subjecting it to supercalender treatment under pressure and heat. Method.