JPH04276312A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the magnetic recording medium which is excellent in all of the corrosion resistance, traveling property and durability in air and corrosive gaseous atmosphere as the magnetic recording medium having a magnetic layer consisting of a ferromagnetic metal as a magnetic material. CONSTITUTION:At last one kind of compds. selected from a benzotriazole phosphonic acid deriv. and benzotriazole deriv. having two hydroxyl groups are made to exist on or in the magnetic layer consisting of the ferromagnetic metal as the magnetic material.

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 such as a magnetic tape, a magnetic disk, or a magnetic drum, which has a magnetic layer made of a ferromagnetic metal on a nonmagnetic substrate.

0002

2. Description of the Related Art Generally, magnetic recording media such as magnetic tapes are easily worn out because the surface of the magnetic layer comes into sliding contact with a magnetic head at a high relative speed during recording and reproduction. In particular, magnetic recording media that have a ferromagnetic metal thin film type magnetic layer formed by vacuum evaporation, or a coating film type magnetic layer made of ferromagnetic metal magnetic powder bound with a binder, have high density recording characteristics. On the other hand, because the hardness of the metal that is the magnetic material is low and the coefficient of friction between it and the magnetic head is high, the magnetic layer is susceptible to wear and damage, and the metal that is the magnetic material gradually oxidizes in the air. Therefore, there was a problem that magnetic properties such as maximum magnetic flux density deteriorated.

Therefore, in the past, a rust preventive agent was applied to the surface of the magnetic layer to improve corrosion resistance, or an aliphatic compound such as a fatty acid or a fatty acid ester, or a fluorine-based compound such as perfluoroalkyl polyether was applied onto the magnetic layer. Measures have been adopted to improve running performance and durability by forming a lubricant film such as JP-A-60-109028 and JP-A-61-11926 to reduce the coefficient of friction.

0004

[Problems to be Solved by the Invention] However, although the above-mentioned conventional rust preventives and lubricants deposited on the surface of the magnetic layer exhibit a certain degree of anti-corrosion and lubricating effect in the initial use of the magnetic recording medium, Since the interaction with the magnetic layer surface is insufficient, it is easy to separate from the magnetic layer surface due to sliding contact with the magnetic head during repeated use, resulting in poor corrosion resistance, runnability,
Durability etc. could not be sufficiently improved.

[0005] In addition, especially when the atmosphere during storage or use of a magnetic recording medium contains corrosive gases such as SO2, NO2, Cl2, etc., the above-mentioned conventional rust preventives cannot be used at all, and this gas is extremely There was a problem in that even a small amount of corrosion of the ferromagnetic metal used in the magnetic layer progresses rapidly, resulting in a significant deterioration of magnetic properties.

In view of the above-mentioned circumstances, the present invention has a magnetic layer made of ferromagnetic metal as a magnetic material, which has corrosion resistance,
The object of the present invention is to provide a magnetic recording medium that has excellent running properties and durability, is resistant to corrosion of the metals mentioned above even in an atmosphere containing corrosive gas, and can maintain high magnetic properties.

[0007]

[Means for Solving the Problems] As a result of extensive studies to achieve the above object, the present inventor has discovered that when a specific benzotriazole compound is present on the surface or inside of a magnetic layer, The compound not only exhibits a very strong anti-corrosion effect, but also provides lubricity to the surface of the magnetic layer, greatly improving corrosion resistance, runnability, and durability, and also prevents deterioration of magnetic properties even in an atmosphere containing corrosive gases. They discovered that this phenomenon was less likely to occur and completed this invention.

That is, the present invention provides a magnetic recording medium comprising a magnetic layer made of a ferromagnetic metal on a non-magnetic substrate, in which a benzotriazolephosphonic acid derivative and a hydroxyl group are added to the surface or inside of the magnetic layer. The present invention relates to a magnetic recording medium characterized in that at least one compound selected from benzotriazole derivatives having two compounds is present.

[0009]

Structure and operation of the invention When the benzotriazole phosphonic acid derivative and the benzotriazole derivative having two hydroxyl groups used in the present invention are present on the surface or inside of a magnetic layer, respectively, they become ferromagnetic, which is a magnetic material. Oxidative corrosion of metals due to oxygen in the air, as well as SO2, NO
2. It exhibits strong corrosion resistance against corrosion caused by corrosive gases such as Cl2, and provides good lubricity to the surface of the magnetic layer. Moreover, the former derivative has a phosphate group in the molecule, and the latter derivative has two hydroxyl groups in the molecule,
Since these phosphoric acid groups and hydroxyl groups have excellent affinity for the ferromagnetic metal that is hydrophilic in the magnetic layer, both are strongly adsorbed to the magnetic layer.

Therefore, in the magnetic recording medium of the present invention, even if the surface of the magnetic layer comes into sliding contact with the magnetic head many times due to repeated use, the above-mentioned derivatives adhered to the surface hardly separate and remain intact. The strong anti-corrosion effect and good lubrication effect are fully exhibited over a long period of time regardless of the atmosphere mentioned above, preventing deterioration of magnetic properties due to corrosion of the ferromagnetic metal used as the magnetic material, and providing stable running performance. Furthermore, the surface of the magnetic layer is less prone to wear and damage, and exhibits excellent durability.

The benzotriazole phosphonic acid derivative and the benzotriazole derivative having two hydroxyl groups are not particularly limited, but the former has the following chemical formula (
For a) and (b), and the latter, compounds represented by the following chemical formulas (c) and (d) are respectively preferred. Furthermore, two or more of these benzotriazole derivatives may be used in combination.

0012

[C5]

[0013]

[C6]

[0014]

[Chemical 7]

[0015]

[Chemical formula 8]

[0016] Note that benzotriazole derivatives that are not phosphonic acid derivatives and compounds that have only one hydroxyl group are not sufficiently adsorbed to the magnetic layer and are easily absorbed by sliding contact between the magnetic layer surface and the magnetic head. It separates from the magnetic layer. Furthermore, benzotriazole derivatives having three or more hydroxyl groups have too strong hydrophilicity and therefore have poor antirust ability.

As described above, the magnetic recording medium to which the present invention is applied is one in which a magnetic layer made of a ferromagnetic metal is provided on a non-magnetic substrate, and this magnetic layer is a ferromagnetic metal thin film. It includes both a mold type and a coating film type in which ferromagnetic metal magnetic powder is bound with a binder. The former ferromagnetic metal thin film type magnetic layer is made of Co, Ni, Fe.
, Co-Ni alloy, Co-Cr alloy, Co-P alloy, C
It can be formed by depositing a ferromagnetic metal such as an o-Ni-P alloy on the surface of a non-magnetic substrate by vacuum deposition, ion plating, sputtering, plating, or the like. The latter coating-type magnetic layer can be formed by preparing a magnetic paint containing magnetic powder made of the same ferromagnetic metal as described above and a binder, applying this paint onto a non-magnetic substrate, and drying it.

In order to have the benzotriazole derivative present on the surface of such a magnetic layer, the derivative is dissolved in a suitable solvent such as ethanol, and the magnetic layer is immersed in this solution, or The above derivative may be uniformly deposited by coating or spraying the same solution on the surface of the magnetic layer and volatilizing the solvent. The amount of this coating is preferably about 0.1 to 5.0 mg/m2; if it is too small, the above-mentioned effect will be insufficient, and if it is too large, it will cause a drop in output or dropout during recording and reproduction.

In the case of a coating type magnetic layer, it is also possible to incorporate a benzotriazole derivative inside the magnetic layer by blending the benzotriazole derivative into the magnetic paint. However, even in this case, it is desirable to set the amount of this derivative to be present on the surface of the magnetic layer in the above-mentioned amount by adjusting the blending amount or by using the above-mentioned means for adhering to the surface.

In addition to using the above-mentioned benzotriazole derivative alone, conventionally used lubricant components such as fatty acids, fatty acid esters, and perfluoroalkyl polyethers may be used in combination with this derivative.

[0021] Binders for the coating type magnetic layer include vinyl chloride resins, polyurethane resins, cellulose resins, vinyl acetal resins, vinyl butyral resins, polyester resins, polyamide resins, and radiation-curable resins. resin,
Any crosslinking agent known for use in magnetic recording media, such as polyisocyanate compounds, can be used. In addition, various conventionally known additives such as abrasives, fillers, antistatic agents, dispersants, and colorants can be appropriately incorporated into the coating-type magnetic layer as necessary.

The magnetic recording medium of the present invention includes a magnetic tape having a synthetic resin film such as a polyester film as a base, a magnetic disk having a disk as a base, a magnetic drum having a drum as a base, etc., in which the surface of the magnetic layer is magnetic during recording and reproduction. It includes various forms that make sliding contact with the head. Also,
The present invention is also applicable to non-magnetic substrates that have no magnetic layer but have a back coat layer on the back surface, and those that have an intermediate layer between the magnetic layer and the substrate.

[0023]

According to the present invention, as a magnetic recording medium having a magnetic layer made of ferromagnetic metal as a magnetic material, corrosion of the magnetic material occurs either in air or in an atmosphere containing corrosive gas. It has low friction with the magnetic head even after repeated use, provides stable running performance, is resistant to abrasion or damage to the magnetic layer, maintains high magnetic properties over a long period of time, and is extremely durable. I can provide something.

According to the second to fifth aspects of the present invention, that is, according to the structure using the specific benzotriazole derivatives represented by the chemical formulas (a) to (d), the above-mentioned corrosion resistance and runnability can be achieved. This has the advantage that the durability effect is particularly well exhibited.

[0025]

EXAMPLES Next, examples of the present invention will be specifically explained in comparison with comparative examples. In the following, parts and % mean parts by weight and % by weight, respectively.

Example 1 A polyester film with a thickness of 10 μm was placed in a vacuum evaporation apparatus, and a Co-Ni alloy was heated and evaporated under a vacuum of 5×(1/100000) Torr to form a thick layer on one side of the film. A ferromagnetic metal thin film made of a Co-Ni alloy with a thickness of 0.15 μm was formed. Then, this is converted into the chemical formula (a)
of the benzotriazole phosphonic acid derivative represented by 0.
After immersing it in a 1% ethanol solution, it was dried to form a protective film made of this derivative, and the film was slit to a width of 8 mm to produce a videotape. The amount of this derivative deposited was 1.0 mg/m2.

Example 2 A videotape was produced in the same manner as in Example 1, except that a compound in which R1 and R2 in the chemical formula (b) were both octyl groups was used as the benzotriazolephosphonic acid derivative.

Example 3 In place of the benzotriazole phosphonic acid derivative, R3 in the above chemical formula (c) is a methylene group, R4 and R
A videotape was produced in the same manner as in Example 1, except that a compound in which both 5 were ethylene groups was used.

Example 4 A videotape was produced in the same manner as in Example 1, except that a compound in which R6 in the chemical formula (d) was a methylene group was used instead of the benzotriazolephosphonic acid derivative.

Comparative Example 1 A videotape was produced in the same manner as in Example 1, except that benzotriazole was used instead of the benzotriazole phosphonic acid derivative.

Comparative Example 2 In place of the ethanol solution of the benzotriazolephosphonic acid derivative, 0.1% of perfluoroalkyl polyether (trade name: Fomblin Z DOL, manufactured by Enimont) was used.
A videotape was produced in the same manner as in Example 1 except that a % Freon solution was used.

Example 5 α-Fe magnetic powder

80 parts Vinyl chloride resin (trade name MR-110 manufactured by Nippon Zeon Co., Ltd.) 12 parts
Polyurethane resin (trade name N-2309 manufactured by Nippon Polyurethane Co., Ltd.) 4 parts Trifunctional low molecular weight isocyanate compound
2 parts (trade name: Coronate L manufactured by Nippon Polyurethane Industries) Cyclohexanone
65 copies
toluene

65 copies

After preparing a magnetic paint by mixing and dispersing the above composition in a ball mill for 100 hours, this magnetic paint was applied onto a polyester film with a thickness of 11 μm to a dry thickness of 3 μm, and dried to form a magnetic coating. formed a layer. Next, this was immersed in the same ethanol solution of benzotriazolephosphonic acid derivative as in Example 1, and then dried to form a protective film made of this derivative, and slit into 8 mm width to prepare a videotape.

Example 6 A videotape was produced in the same manner as in Example 5, except that the same compound as in Example 3 was used in place of the benzotriazolephosphonic acid derivative.

Example 7 A videotape was produced in the same manner as in Example 5, except that 2 parts of the benzotriazolephosphonic acid derivative represented by the chemical formula (a) above was added to the composition of the magnetic paint.

Comparative Example 3 A videotape was produced in the same manner as in Example 5, except that benzotriazole was used instead of the benzotriazolephosphonic acid derivative.

Comparative Example 4 A videotape was produced in the same manner as in Example 5, except that the Freon solution of perfluoroalkyl polyether used in Comparative Example 2 was used instead of the ethanol solution of the benzotriazolephosphonic acid derivative. .

The video tapes of the above Examples and Comparative Examples were tested for durability and corrosion resistance, and the results shown in Table 1 below were obtained. In addition, the durability test is
The video tape was played back under conditions of 25° C. and 60% RH with a head load of 5 g and a running speed of 0.048 m/sec, and the number of runs until the output decreased by 3 dB from the initial output was measured. In addition, the corrosion resistance test was conducted on video tape at 60°C.
, left for one week under 90% RH conditions, and SO2
The retention rate of saturation magnetization when left in an environment with a concentration of 10 ppm for one day was measured using a VSM (vibrating sample magnetometer), and this measured value was calculated as the ratio (%) to the saturation magnetization of the videotape before being left. ).

[0039]

[Table 1]

From the results in Table 1, it can be seen that the video tapes of the present invention (Examples 1 to 7) are superior to the conventional video tapes (Comparative Examples 1 to 4), regardless of whether the magnetic layer has a ferromagnetic metal thin film type or a coating type. ), it has significantly superior durability and corrosion resistance, and it can be seen that even in an atmosphere containing corrosive gases such as SO2, corrosion of the magnetic material and resulting deterioration of magnetic properties hardly occur.

Claims (5)

[Claims] Claim 1: A magnetic recording medium comprising a magnetic layer made of a ferromagnetic metal on a non-magnetic substrate, wherein the magnetic layer has a benzotriazolephosphonic acid derivative and two hydroxyl groups on the surface or inside the magnetic layer. A magnetic recording medium characterized in that at least one compound selected from benzotriazole derivatives is present. 2. The magnetic recording medium according to claim 1, wherein a compound represented by the following chemical formula (a) is used as the benzotriazole phosphonic acid derivative. 3. The magnetic recording medium according to claim 1, wherein a compound represented by the following chemical formula (b) is used as the benzotriazole phosphonic acid derivative. 4. The magnetic recording medium according to claim 1, wherein a compound represented by the following chemical formula (c) is used as the benzotriazole derivative having two hydroxyl groups. 5. The magnetic recording medium according to claim 1, wherein a compound represented by the following chemical formula (d) is used as the benzotriazole derivative having two hydroxyl groups.