JPS58159239A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To faithfully record and reproduce original sound, by forming a magnetic layer of iron nitride or an alloy-nitride on an under layer contacting with a nonmagnetic carrier and by forming a magnetic layer of iron or an iron alloy on the nitride layer. CONSTITUTION:The figure shows an oblique section of a 2-layered magnetic recording medium. The surface of the nonmagnetic carrier 1 for magnetic recording is coated with a magnetic layer of Fe4N or a mixture of Fe4N with Fe or an Fe alloy as a magnetic material to form the under layer 2, and the layer 2 is coated with Fe or an Fe alloy as a magnetic material to form the upper layer 3. Thus, the linearity of the frequency characteristics is improved, the dynamic range is extended, and original sound can be recorded and reproduced faithfully.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and particularly to a two-layer magnetic recording medium.

Generally, magnetic recording media mainly composed of iron oxide such as r -Fe2O3 are used, and recently, in order to increase the coercive force HeO value, CrO2, Co-coated film r -Fe2O
Furthermore, metal tapes using alloy-based fine particles containing iron as a main component have been proposed. The metal tape has a deep bias in the high frequency range and a shallow bias in the low frequency range. In order to improve this, it is known that K is provided with two magnetic layers, using a low coercive force magnetic powder in the lower layer and a high coercive force magnetic powder in the upper layer. Here, as a two-layer coated magnetic recording medium for metal bias, γ-Fe 203 is used as the lower layer.
CO adsorbed γ-Fe, 203. CrO2 is mixed with iron or iron alloy to increase the average coercive force to 800 oe~too.
Even as an OE, the saturation magnetization is small at around 70 amμ/g, so the desired sensitivity and dynamic range are not expanded, and high inputs cannot be recorded without distortion when used in general music, making it impossible to obtain satisfactory characteristics. .

The present invention was developed in view of the above-mentioned drawbacks, and uses a magnetic material with low coercive force and high saturation magnetization to expand the dynamic range of both low and high magnetic fields, and to create a two-layer magnetic coating that can faithfully record and reproduce the original sound. Its purpose is to provide recording media.

In order to achieve the above object, the present invention has a saturation magnetization of 120 emjI/11 or more and a coercive force of 600 o.
Using iron nitride (Fe4N), which is an iron nitride of 900 as, a mixture of Fe and Fe4N or a magnetic powder of Fe4N with an average coercive force of 800 to 900 oersted is applied as the lower layer, and the upper layer is coated with a conventional coercive force of 1100 to 1200 oersted. The purpose is to provide a 92-layer coated magnetic recording medium by coating Oersted's iron or iron alloy magnetic powder.

Hereinafter, two embodiments of the present invention will be described in detail with reference to the drawings. 1st
The figure is a partially sectional perspective view of the two-layer coated magnetic recording medium of the present invention, (1) is a non-magnetic magnetic recording carrier;
Fe is in contact with the upper surface of the carrier (11) as the lower layer (2).
A magnetic layer consisting of aN or Fe 4N and Fe or Fe alloy magnetic material is fully coated, and Fe or F/alloy magnetic material is coated on the lower layer (2) to form the upper layer (3). Two pieces. Specific Examples of the Invention A magnetic material for the AO lower layer, which will be described in detail below, was prepared with the following composition.

Iron nitride (FeaN) 10
0 parts vinyl chloride vinyl acetate copolymer 10 parts urethane prepolymer dispersant lecithin 2I vinyl chloride stabilizer methyl ethyl ketone 150 J toluene After kneading the above ingredients in a ball mill for 72 hours, 33 parts of a crosslinking agent was added to make a non-magnetic paint. And so. This was applied to a polyester film to a thickness of 3.5 μm, the magnetic particles were oriented, and after drying, the film was surface treated and heated at 40° for 48 hours to cause crosslinking. Next, the following composition was prepared as an upper magnetic coating. As a magnetic material for the upper layer.

Iron magnetic powder (Fe) Zoo
Parts Vinyl chloride Vinyl acetate copolymer 13I Urethane prepolymer 7I Dispersant Lecithin 21 Vinyl chloride Stabilizer Methyl ethyl ketone 200 parts Toluene After mixing the above components in a ball mill for 72 hours, a thickness of 2. θ~2. ．． Apply the powder to a thickness of 5 μm, orient the magnetic particles, dry it, and then perform a surface treatment to complete the magnetic recording medium as shown in Figure 1. After mixing, the same mixture as in the lower layer formulation example was used by dispersing it in the inder composition.

Example 2 40 parts of rFI4N (
Weight r-Fe 60# Vinyl chloride vinyl acetate copolymer 101 Urethane prepolymer 10# Vinyl chloride stabilizer
2#TDO (dispersant) 21 Methyl ethyl ketone 150I Toyani 7
80 l abrasive
The composition of 201 was prepared under the same conditions as in Example (1). For upper layer (3): γ-Fe 100 parts Vinyl chloride vinyl acetate copolymer 131 Urethane polymer 71 Vinyl chloride stabilizer 2° TDO (dispersant)
2# Methyl ethyl ketone
180g toluene
80 l abrasive
The composition of No. 201 was prepared under the same conditions as in Example (No. 11).

) The MOL (eel i% output level), 5OL (saturation output level), and sensitivity-lfM relationship configured as described above are shown in the curves in FIG. In the above characteristic curve, the horizontal axis shows the frequency and the vertical axis shows the output level. Shows all levels, sensitivity is -2 OdB
Curve B, which is the output level at the time of input, is the characteristic of a magnetic recording medium coated with iron or iron alloy magnetic material.In song #C, the lower layer (2) is γ-Fe2O3, CrO3. ,
A case is shown in which C-brazed T-Fe2O3 and iron or iron alloy magnetic material are used. As shown by curve C, when A magnetic material of 300 to 800 oersted is used for the lower layer, the low frequency sensitivity and M
The OL decreases as shown in curve dc in a magnetic recording medium coated with iron or red iron alloy magnetic powder. The present invention increases the intensity and MOL over the entire -f-dio band as shown by curve A.

The present invention uses iron nitride (Fe4N) for the lower layer and iron alloy magnetic powder for the upper layer as a cassette tape for metal bias, thereby improving the frequency characteristic If characteristic and expanding the dynamic range over a wide range. This magnetic recording medium has a feature that enables recording and reproduction that is faithful to the original sound, which is not possible with conventional metal bias cassette tapes.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the dual-layer magnetic recording medium of the present invention, with a part thereof being inclined, and FIG. 2 is a tlL number time curve diagram comparing the characteristics of the present invention and a conventional magnetic recording medium. be. In the mouth: +1lri non-magnetic magnetic carrier, (2) is the underlying magnetic material. +311i- Upper layer magnetic material.

Claims (2)

[Claims] (1) In a magnetic AL spherical medium in which 14 grains of material are tilted in a 1- direction on a non-exited t1 phase, iron nitride or iron alloy nitride is added to the non-magnetic carrier in the lower tank. 1. A magnetic recording medium comprising a magnetic layer and an IC outer layer on the iron nitride or Fuai nitride magnetic outer layer. (2) Iron or iron alloy magnetic material with a coercivity of 1100 to 1200 oersted is heated to a thickness of 20γ25μm.
- Coercive force of 800 to 900 els anoto t b-zu 4
1600 to 800 1600 to 800 with a self-loading magnetic recording medium of 1600 to 800. (Erste Sotoshi) Retaining power: A combination of 800 to 900 elsnat was prepared by mixing J's rod material with iron alloy magnetic material and adjusting the coercive force to 800 to 900 elsna. 45-L fi of Section 1, Section 1, IR2 of Section 15
Recording medium.