JPH08153321A - Magnetic recording medium - Google Patents

Abstract

PURPOSE: To provide a magnetic recording medium having satisfactory electromagnetic transducing characteristics, still durability, mold resistance during storage and pot life by using iron nitride power having prescribed characteristics as magnetic powder used in the magnetic layer of a magnetic recording medium. CONSTITUTION: The top of a filmlike substrate is coated with a magnetic layer to obtain the objective magnetic recording medium. Magnetic powder used in the magnetic layer is iron nitride powder having 160-210emu/g saturation magnetization δs , 1,500-2,500Oe coercive force, an acicularity ratio of 5-15 and 0.05-0.15μm major axis size and an org. material selected from among C11 H17 CONC12 , C11 H19 NOS, C9 H4 C12 FNO2 S, C9 H11 , N2 O2 C12 FS2 , C9 H6 N2 S3 , C8 H14 N4 , C16 H22 ClN3 O, C8 H10 O4 Br2 and C6 H3 OBr3 is contained in the magnetic layer. A magnetic coating material used has satisfactory viscosity and the resultant magnetic recording medium has improved electromagnetic transducing characteristics, still durability, surface properties and preservability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium,
In particular, the present invention relates to a magnetic recording medium that achieves high electromagnetic conversion characteristics and excellent reliability and storability.

[0002]

2. Description of the Related Art In recent years, the magnetic characteristics of information recording media have been improved so as to realize higher recording density with an increase in recording capacity. Also,
At the time of high density recording / reproduction, the surface roughness of the medium magnetic layer has a great influence on the electromagnetic conversion characteristics. Therefore, it is necessary to make the surface roughness of the medium as smooth as possible.

However, if the surface of the medium magnetic layer is made smooth, there is a problem that reliability, particularly still resistance, deteriorates.
As a magnetic recording medium, it is necessary to satisfy these contradictory characteristics, but there is still no sufficient one.

Further, in general, when a magnetic coating material is produced by using magnetic powder having high magnetic characteristics, the pot life is short and the coating material properties change drastically with time. In addition, the produced media may be stored for a long time before use or after recording. In this case, mold may be generated on the medium depending on the storage period, resulting in dropout when recording / reproducing signals,
There is a problem that the recording / reproducing is impossible because the apparatus is dirty, especially the magnetic head is extremely dirty.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a magnetic recording medium which realizes high electromagnetic conversion characteristics, good reliability and storability. In a magnetic recording medium obtained by coating a magnetic layer on a support, the magnetic powder used for the magnetic layer is iron nitride-based, and the saturation magnetization σ _s is 160 to 210.
emu / g, coercive force Hc of 1500 to 2500 Oe, acicular ratio of 5 to 15 and major axis length of 0.05 to 0.15 μm,
The magnetic _{layer, C 11 H 17 ONC l2 S} , C 11 H 19 NOS,
_{C 9 H 4 C l2 FNO 2} S, C 9 H 11 N 2 O 2 C l2 F
_{S 2, C 9 H 6 N} 2 S 3, C 8 C l4 N 4, C 16 H 22 C
By containing at least one of the organic substances 1N ₃ O, C ₈ H ₁₀ O ₄ Br ₂ and C ₆ H ₃ OBr ₃ , high electromagnetic conversion characteristics, still resistance, surface properties and storage characteristics are improved, and A magnetic recording medium with a good pot life (paint viscosity) of magnetic paint was realized.

[0006]

EXAMPLE The present invention relates to a coating type magnetic recording medium, an iron nitride-based magnetic powder and the magnetic _{layer, C 11 H 17 ONC l2 S} , C 11
_{H 19 NOS, C 9 H 4} C l2 FNO 2 S, C 9 H 11 N 2
O _{2 Cl 2} FS ₂ , C ₉ H ₆ N ₂ S ₃ , C ₈ C
_{l4 N 4, C 16 H 22} ClN 3 O, C 8 H 10 O 4 Br 2,
By containing at least one organic substance of C ₆ H ₃ OBr ₃ , it is possible to realize high electromagnetic conversion characteristics and good reliability and storability.

That is, in order to realize high electromagnetic conversion characteristics, it is effective to use fine magnetic powder having high magnetic characteristics.

In the present invention, as the magnetic powder having high magnetic properties, it is effective to use the iron nitride-based magnetic powder satisfying <Chemical formula 1>, which has a higher saturation than the widely used metal magnetic powder. It shows the amount of magnetization, and was effective in realizing good magnetic characteristics.

[0009]

Embedded image

Regarding the composition of the magnetic powder, the saturation magnetization amount σ _s
Is 160 to 210 emu / g, holding power Hc 1500 to 25
00 Oe, acicular ratio 5 to 15, major axis length 0.05 to 0.
By setting the thickness to 15 μm, high magnetic properties and good chemical stability were obtained.

Regarding the saturation magnetization amount σ _s of the magnetic powder, when the saturation magnetization amount σ _s is 160 emu / g or less, the saturation magnetic flux density Bm of the magnetic layer after mediumization is not sufficient to satisfy the electromagnetic conversion characteristics. Didn't arrive. If the magnetic powder has good chemical stability, the saturation magnetization σ _s is 21
A magnetic powder of 0 emu / g or more could not be produced.

If the acicular ratio of the magnetic powder is less than 5, the orientation will be poor, the squareness ratio after mediumization will be low, and good electromagnetic conversion characteristics cannot be realized, and the acicular ratio will be 15
If it exceeds, the magnetic properties and electromagnetic conversion properties after being made into media become poor. It is presumed that the cause of this is that it is difficult to disperse the magnetic powder in terms of shape and that the magnetic powder is destroyed.

If the major axis length of the magnetic powder is less than 0.05, it is difficult to improve the magnetic properties,
Also, dispersion became difficult, and as a result, the magnetic properties of the magnetic layer after being made into a medium were low. When the major axis length exceeds 0.15 μm, the reproduction output and the C / N ratio when the short wavelength signal is recorded / reproduced.
Became lower.

The holding power Hc of the magnetic powder is 1500
If it is Oe or less, the reproduction output at the time of recording / reproduction of the short wavelength signal is low, and if it is 2500 Oe or more, the reproduction output at the time of recording / reproduction of the long wavelength signal is low, which further deteriorates the erasing rate.

[0015] hitting To produce a magnetic layer of the medium to make a magnetic coating using the magnetic powder described above, as an additive in the magnetic _{layer, C 11 H 17 ONC l2 S} , C 11 H 19 NOS, C _{9
H 4 C l2 FNO 2 S,} C 9 H 11 N 2 O 2 C l2 F
_{S 2, C 9 H 6 N} 2 S 3, C 8 C l4 N 4, C 16 H 22 C
By containing at least one organic substance of 1N ₃ O, C ₈ H ₁₀ O ₄ Br ₂ and C ₆ H ₃ OBr ₃ , high electromagnetic conversion characteristics, still resistance and storage characteristics, and good paint pot life. Realized a new magnetic recording medium.

Here, the amount of the above additive added is preferably 0.01 to 1.0% (parts by weight),
If it is less than this range, the still resistance, storability and pot life of the paint will not be sufficient. Further, when the addition amount is large, the coating film strength is lowered and the still resistance is deteriorated.

Specific examples of the magnetic recording medium according to the present invention will be described below. The magnetic paint was prepared with the following composition.

Magnetic powder 100 parts by weight Vinyl chloride (MR-110 manufactured by Nippon Zeon) 10 parts by weight Urethane (UR8300 manufactured by Toyobo) 10 parts by weight α-alumina 2 parts by weight Carbon black 1 part by weight Isocyanate (Coronate L manufactured by Nippon Polyurethane) 4 Parts by weight palmitic acid 2 parts by weight additive XY parts by weight The above mixture was mixed and dispersed by a sand mill. Tables 1 and 2 show the magnetic powder and additives used here and the amounts thereof added, respectively.

[0019]

[Table 1]

[0020]

[Table 2]

The samples were evaluated for electromagnetic conversion characteristics, still resistance, mold generation during tape storage, and pot life of magnetic paint before coating.

The electromagnetic conversion characteristic is that the tape is slit into a width of 1/2 inch and wound in a cassette for M-2 system,
The head amplifier of the deck was modified and the ratio C / N of the reproduction output of the sine wave signal of 10 MHz and the noise of 9 MHz was measured.

The still resistance was evaluated by winding the tape in a VHS type cassette and using a VHS type deck. The test environment is 20 ° C. and the humidity is 10%.

As for the mold generation condition when the tape is stored, the tape is wound in a VHS system cassette, and this cassette is set to 3
The mold generation state of the tape after storage for 30 days in an environment of 0 ° C and humidity of 90% was visually observed. The evaluation results are shown in Table 3, Table 4, Table 5 and Table 6.

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

[0028]

[Table 6]

According to the above-mentioned evaluation, Examples 1 to 16 show electromagnetic conversion characteristics, still resistance, and a mold generation state after storage,
It can be seen that the pot life of the paint is excellent.
On the other hand, Comparative Examples 6 to 10 using the metal magnetic powder had extremely low electromagnetic conversion characteristics, and Comparative Examples 4 and 5 containing a large amount of the additive had poor still resistance. In Comparative Examples 1 to 3 in which the additive was not added or the additive amount was small, mold generation was recognized after storage.

On the other hand, in the example, an iron nitride type having high magnetic properties is used, but it shows a good pot life. That is, the pot life is measured by measuring the paint during storage and evaluated by the change with time, and the smaller the change with time, the better.

[0031]

The magnetic recording medium according to the present invention, which has been described in detail above, has the effects of achieving electromagnetic conversion characteristics, stillness resistance, suppression of mold generation during storage, and good pot life.

Claims (1)

[Claims] 1. A magnetic recording medium comprising a film-shaped support coated with a magnetic layer, wherein the magnetic powder used in the magnetic layer is iron nitride and the saturation magnetization σ _s is 160-.
210emu / g, coercive force Hc is 1500-2500O
e, acicular ratio 5 to 15, major axis length 0.05 to 0.15μ
and m, the magnetic _{layer, C 11 H 17 ONC l2 S} , C 11 H 19
_{NOS, C 9 H 4 C l2} FNO 2 S, C 9 H 11 N 2 O 2
C _l2 FS ₂ , C ₉ H ₆ N ₂ S ₃ , C ₈ C _{l 4} N ₄ , C
₁₆ H ₂₂ ClN ₃ O, C ₈ H ₁₀ O ₄ Br ₂ , C ₆ H ₃ OB
A magnetic recording medium containing at least one of the organic substances of r ₃ .