JPS62192928A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent dimensional stability and stable runnability by treating a nonmagnetic base at a specific temp. and relative humidity, then forming a layer contg. a resin curable by radiation thereon. CONSTITUTION:After the nonmagnetic base is treated at 60-130 deg.C and >=60% relative humidity, the layer contg. the resin curable by radiation is formed on the nonmagnetic base. A coating compd. for the magnetic layer is prepd. by kneading and dispersing the compsn. consisting of ferromagnetic Co-deposited Fe2O3, polyurethane resin curable by radiation, vinyl chloride/vinyl acetate copolymer, carbon black, polishing agent, lecithin, and solvent mixture by using a ball mill and sand mill then filtering the mixture with a filter of 1mum average pore size. The magnetic coating compd. is coated on a polyster film treated at 80 deg.C and 80% relative humidity and after the film is subjected to magnetic field orientation and drying treatment, the film is subjected to a mirror finishing treatment by a super calender roll then to irradiation of electrons in gaseous nitrogen flow.

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 disks used in audio and video equipment, computers, and the like.

BACKGROUND OF THE INVENTION In recent years, the above-mentioned magnetic recording media are moving toward high-density recording, and therefore the recording wavelength is becoming shorter, the recording track width is narrower, and the recording medium thickness is becoming thinner. As a result, the playback output, S
Electromagnetic conversion characteristics such as N ratio are generally becoming disadvantageous. Conventional magnetic recording media 2t, -,; The so-called thermosetting magnetic paint containing a magnetic agent was coated on a non-magnetic support, dried, calendered, and then heat-treated for a relatively long period of time. Various problems have arisen in manufacturing magnetic recording media with smooth surfaces. For example, variations in coating film properties due to the short pot life of magnetic paints, or variations in the surface properties of the magnetic layer, not only due to the dispersibility of the magnetic powder but also due to the surface properties of the non-magnetic powder support on which the magnetic layer is formed. Problems include the fact that it is extremely susceptible to the surface properties of the bank coat layer formed on the non-magnetic support, and the degree of influence also slopes in the longitudinal direction of the product. In order to solve these problems with conventional thermosetting magnetic recording media, a so-called radiation-curable magnetic recording medium was proposed, in which a magnetic layer containing a radiation-curable binder is irradiated with radiation to harden the coating. Many have already been done.

Radiation-curable resins are generally radiation-sensitive modified thermosetting resins, and specific examples include acrylic acid, methacrylic acid, and methacrylic acid. Or the ester compounds of I71 et al.
1: Cross-linking of 71 (meth)acrylic two-handed bonds, double bonds of maleic acid, maleic acid derivatives, etc. (by radiation irradiation) or by introducing VC in 4 N to polymerize γ-11. Other radiation irradiation (f) can be used as long as it has a consonant double bond that crosslinks or polymerizes.
It can be used alone or in combination with several tens of Φ, and if you feel safe, you can also use thermosetting I (III') with III fat. As radiation, electron beam accelerator 4-・ray Electron beams are used as the source, γ-rays are Co60 as the ray σ9, and X-rays' and q are used as the radiation source.
1. Control and production of absorption line h1 - “Introduction of culm line ’\,
From the viewpoint of shielding properties of electric NC radiation Q and γ rays, the line curing method using an electron beam accelerator is advantageous. Specific examples of electron beam accelerators include the JI low-level type 7-pure accelerator (I Curtain System) manufactured by Energy Science, Inc. in the United States, and the Nissin High Voltage Co., Ltd. sugyanning I) 11 low line fj'f city of Taifu - r swamp +
IJJf effect・+8嵜)′、Nowaday 1、Dou/ζ、Radiation crosslinking (/In the case of N2 gas, CO2 gas, etc.) Magnetic 1/1 layer (
・(It is effective to irradiate it. Irradiation in the air: radicannoyl 1 or acid + - a/) in the binder! i! I [(6
1 = 1) The polymerization and curing of the binder is caused by IS1 ↓.
.

Conventionally, magnetic media (for example, #, n-diotave, and b-7o tape attached to a sumo wrestler's throat) have been used and stored in environments with rapid indoor temperature changes.
■I was able to do it. In recent years, radio cassette players, biophonic cameras, 8nln
Widely used for video recording, etc. 6I: Used in high and low temperature environments with magnetic recording media
1.It is becoming more and more common to keep it! Samurai has a magnetic field of 4 [4 roku medium's 1'] when the temperature is high and high humidity.
All method deformations are very easy to cause 71 line defects such as the occurrence of skew and the occurrence of curls in the output (lower g) than melting. With the diversification and high performance of 6-beams, the running reliability of the magnetic recording media has been emphasized, and the 4-i'
l't: HofL is required.

Conventionally, in order to solve all of these problems, the use of paste fill with a low thermal shrinkage rate (for example, JP-A-59-11531, JP-A-59-107-424, JP-A-60-1) has been proposed.
5830, Japanese Patent Application Laid-Open No. 60-98524)
There are proposals such as using a base film that has been heat-treated in advance (for example, Japanese Patent Application Laid-Open No. 59-135632-Yumi and Japanese Patent Application Laid-Open No. 60-103517).

Problems to be Solved by the Invention Recently, as the density of magnetic recording media has increased, base films have become thinner and their mechanical strength has weakened.
Illusion of a single magnetic recording device containing Fl, I resin: Although it has many features as mentioned above compared to those using conventional thermosetting resins, there is no residual stress relaxation process during thermosetting. , making the dimensional stability of magnetic recording media even more difficult. Therefore, with conventional methods, it is difficult to maintain the characteristics of magnetic recording media containing radiation-curable resin at high temperatures.
, for 4Q.

In the present invention U, in view of the above problems, even if a magnetic recording body formed by forming a layer containing radiation hardening 3 (11 lubricant) is placed at a product temperature or under high temperature and high humidity, the magnetic recording medium will not be affected by heat shrinkage. The object of the present invention is to provide a magnetic recording medium that has small deformation, excellent compliance with legal requirements, and stable running performance.

Means for Solving the Problems In order to solve the above problems, the non-magnetic support was heated to 60°C
The present invention provides a method for manufacturing a magnetic recording medium, in which a layer containing a radiation-curable resin is formed on the non-magnetic support after processing at a temperature of 130° C. and a relative humidity of 60% or more.

Effect of the present invention: By applying not only heat to the base film in advance, but also humidity, moisture works with the plasticizer (~) to reliably and quickly remove residual strain inside the non-magnetic support. can be removed to improve dimensional stability under high temperature and high humidity conditions.

EXAMPLES Hereinafter, examples of the present invention will be specifically explained using a magnetic tape. Note that all parts of components mentioned in the examples indicate weight ratios.

As a non-magnetic support, polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate; polyolefins such as polyethylene and polypropylene (cellulose triacetate), ceyv o -methai acetate, cellulose acetate butyrate, cellulose acetate Examples include cellulose derivatives of propionates; vinyl resins such as polyvinyl chloride and polyvinylidene chloride; plastic films such as polycarbonate, polyimide, polyetherimide, and polyamideimide; any of them can be used.

(Example 1) Adjustment of paint (A) for magnetic layer; Ferromagnetic Go coating-Fe 20.

100 parts Electron beam curable polyurethane resin 10 parts Vinyl chloride vinyl acetate copolymer 10 parts Carbon black
3-part abrasive (A1203)
4 part lecithin
1 part mixed solvent (MEK/l-luene/
300 parts anone = 1/1/1) - The above composition was cross-dispersed using a ball mill and a sand mill, and then filtered through a filter with an average pore size of 1 μm to prepare a magnetic layer coating material [A]. Magnetic paint [A'l] was applied onto the polyester film shown in Table 1 treated at 80°C, relative humidity 80% for 24 hours, subjected to magnetic field orientation, drying treatment, mirror finishing treatment using a super calender roll, and then Acceleration voltage 160k
Electron beam irradiation was carried out under a nitrogen stream under conditions such that v absorbed dose was s Mrad to obtain a raw fabric roll having a magnetic layer with a thickness of 9 mm and a width of 5 μm. This is 1
A videotape sample (250° C. length) was produced by cutting it into a width of /2 inch.

(Example 2) -I-Magnetic coating [A] was applied onto the polyester film shown in Table 1 treated at 120°C and relative humidity of 80°C for 12 hours, subjected to magnetic field orientation and drying treatment, Mirror finishing treatment with super calender roll, then acceleration voltage 160
Electron beam irradiation was performed under a nitrogen stream under conditions such that the kv absorbed dose was 8 Mrad, and a raw roll having a magnetic layer with a thickness of 5 μm was obtained. This was cut into 1/2 inch width to produce a videotape sample (length: 250°C).

(Comparative Example 1) The above magnetic paint (A,) was applied onto the polyester film shown in Table 1, subjected to magnetic field orientation, and drying treatment, followed by mirror finishing treatment using a super calender roll, and then an accelerating voltage of 165
Electron beam irradiation was performed in a nitrogen stream under the conditions of kV and absorbed dose of 8 Mrad to obtain a raw roll having a magnetic layer with a thickness of 5 μm. Cut this into 1/2 inch width and make a videotape sample (25
0°C length) was manufactured.

(Comparative Example 2) Magnetic paint [A] described in Table 1 was applied to the polyester film shown in Table 1 and treated at 80°C for 24 hours. After being subjected to magnetic field orientation and drying treatment, mirror polishing was performed using a super calender roll. After the processing, electron beam irradiation was performed under a nitrogen stream at an acceleration voltage of 165 kV and an absorbed dose of a Mrad to obtain a raw roll having a magnetic layer with a thickness of 5 μm. This was cut into 1/2 inch width to produce a videotape sample (250rr, 1 length).

(Comparative Example 3) Magnetic paint (Al) was applied on top of the polyester film shown in Table 1 treated at 120°C for 12 hours, magnetically oriented,
After the drying process, a mirror polishing process was performed using a super calender roll, and then electron beam irradiation was performed under a nitrogen stream at an acceleration voltage of 1651 MIr and an absorbed dose of a Mrad to form a raw fabric roll having a magnetic layer with a thickness of 6 μm. I got it. Cut this into 1/211 inch width and try video tape *'l (2som1
4) Blue [7/ko〇 (Comparative Example 4) The above magnetic paint []A] was applied to the polyester film shown in Table 1 treated at 140°C relative 1:fi% H dust so% for 10 hours. subjected to ff1ni, magnetic field orientation, and drying treatment 1-/
After that, mirror polishing treatment was performed using a super calender roll, and then electric wire irradiation was performed under a nitrogen stream under the conditions of accelerating soil at 160 kV and SMrad as an absorption line meter, to a burial depth of 6 μm.
A raw fabric with a magnetic layer [J-le? ! ) /child. Cut this into 1/2 inch width and videotape test t1 (25o
, 71 length) were produced.

In each of the above Examples and Comparative Examples, the results shown in Table 2 were obtained using 1 (I et f'l / and magnetic tape test Fl). /The surface of the toe base has a matte texture,
Vertical wrinkles occurred, causing poor running.

1) Heat shrinkage rate Heat treatment conditions: 100°C, 1 hour Heat shrinkage rate - (L-L')/L x 1oo (related) L:
Length of sample tape before heat treatment (at 30°C) L Length of sample tape after heat transfer treatment (t30°C)

3) Running performance VH3 type VTR (NV-820 manufactured by Shoto Denki Sangyo Co., Ltd.)
0) was run under an environment of 60''C to check its stability.

Effects of the Invention As described above, according to the present invention II, on the non-extruded f1 support,
In a method for manufacturing a magnetic recording medium comprising forming a layer containing a radiation-curable resin, the non-magnetic support is heated at 60°C to
By treating the magnetic recording medium at a temperature of 130°C and a relative humidity of 60 or higher before coating, the magnetic recording medium will not shrink due to heat shrinkage even if the magnetic recording medium is placed under high temperature or high temperature and humid conditions. It is possible to provide a magnetic recording medium that exhibits small deformation, excellent dimensional stability, and stable lL behavior. However, it is needless to say that the present invention is applicable not only to magnetic Arp but also to other magnetic recording media such as magnetic disks and magnetic cards.

Claims (1)

[Claims] In the method for manufacturing a magnetic recording medium, the non-magnetic support is treated at a temperature of 60° C. to 130° C. and a relative humidity of 60% or more, and then a layer containing a radiation-curable resin is formed on the non-magnetic support. A method for manufacturing a magnetic recording medium, characterized by: