JPS6234324A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To extend the still reproduction life of a titled medium, to decrease the rate of deterioration and to improve the durability and corrosion resistance thereof by providing a protective film layer of an org. high-polymer compd. on a protective film layer of a titanium oxide provided on the surface of a thin ferromagnetic metallic film. CONSTITUTION:The protective film layer 3 consisting of the titanium oxide formed on the thin ferromagnetic metallic film 2 is formed by depositing the titanium oxide by a method such as vacuum deposition or sputtering on the layer 2. Although this layer 3 has a large coefft. of friction with a magnetic head, etc., the protective film layer 4 consisting of the org. high-polymer compd. contg. carbon or carbon atoms is provided thereon. The direct sliding contact of the layer 3 with the magnetic head is blocked by the layer 4, by which the excellent corrosion preventive effect of the layer 3 is exhibited and the corrosion resistance is improved without deteriorating the durability.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic recording medium having a ferromagnetic metal thin film layer as a magnetic recording layer, and more particularly relates to the above-mentioned magnetic recording medium having excellent durability and corrosion resistance. .

[Conventional technology]

A magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film layer is
It is usually made by depositing metals or their alloys on a base film by vacuum evaporation, sputtering, etc., and has characteristics suitable for high-density recording, but on the other hand, it has a high coefficient of friction with the magnetic head (and wears out). It is easily damaged and is subject to gradual oxidation in the air, resulting in deterioration of magnetic properties such as maximum magnetic flux density.

For this reason, efforts have been made to improve durability and corrosion resistance by providing various protective film layers on the ferromagnetic metal thin film layer. For example, by providing a titanium oxide film layer with excellent corrosion resistance, (Unexamined Japanese Patent Publication No. 5'l-147133)
In addition, a fluorine-based/I21 lubricant may be applied (Japanese Patent Application Laid-Open No.
8-94130), and furthermore, it has been proposed to plasma-polymerize a monomer gas of an organic compound to provide a plasma-polymerized protective film layer of an organic compound (Japanese Patent Laid-Open No. 13231-1983).

[Problem that the invention seeks to solve]

However, although a titanium oxide film layer provided on a ferromagnetic metal thin film layer has excellent corrosion resistance, it has a large coefficient of friction with magnetic heads, etc., and lacks durability. Those with an fk agent layer or a plasma polymerized protective film layer of an organic compound are
Corrosion resistance is still not sufficiently good, and durability and corrosion resistance have not yet been sufficiently improved.

[Means for solving problems]

This invention was made as a result of various studies in view of the current situation. First, a first protective film layer made of titanium oxide is provided on the surface cloth of a ferromagnetic metal thin film layer, and then a first protective film layer made of titanium oxide is provided on the surface fabric of the ferromagnetic metal thin film layer. By providing the second protective film layer made of an organic polymer compound containing carbon atoms, the coefficient of friction with the magnetic head etc. is made sufficiently small, and the durability and corrosion resistance are sufficiently improved.

In this invention, the first protective film layer made of titanium oxide formed on the ferromagnetic metal thin film layer is formed by depositing titanium oxide on the ferromagnetic metal thin film layer by a method such as vacuum evaporation, sputtering, or ion blating. For example, T i 02 is preferably used as the titanium oxide. The protective film layer made of this type of titanium oxide formed in this way has a high coefficient of friction with magnetic fields, etc., but is further coated with carbon or an organic polymer compound containing at least carbon atoms. When a second protective film layer made of titanium oxide is provided, direct sliding contact with the magnetic head etc. is blocked by this second protective film layer, and the extremely excellent corrosion resistance effect of the protective film layer made of titanium oxide is maintained. Corrosion resistance is sufficiently improved without reducing durability. Further, the protective film layer made of this type of titanium oxide has extremely good adhesion to the ferromagnetic metal thin film layer made of a metal magnetic material, and is firmly adhered to the ferromagnetic metal thin film layer. The layer thickness is between the ferromagnetic metal thin film layer and the second protective film layer, and is 10 Å in order to fully exhibit corrosion resistance.
It is preferable to do the above. However, the total thickness of the second protective film layer made of carbon or an organic polymer compound containing at least carbon atoms, which is further laminated on top of this, is 50 mm.
If it becomes thicker than 0, the spacing loss will increase and the electromagnetic conversion characteristics may deteriorate, so this second
It is preferable that the total thickness with the protective film layer is 500 Å or less.

In addition, the protective film layer made of carbon is deposited on the first protective film layer made of titanium oxide, and carbon is coated on the ferromagnetic metal thin film layer by a method such as vacuum evaporation, sputtering, or ion blasting. It is formed by wearing. The protective film layer made of this type of carbon formed in this way has an amorphous structure and has a small coefficient of friction with magnetic heads, etc., and has a first protective film made of titanium oxide formed on the ferromagnetic metal thin film layer. It prevents the first protective film layer from coming into direct sliding contact with the magnetic head, etc., and also sufficiently reduces the coefficient of friction and sufficiently improves wear resistance. Therefore, when the second protective film layer made of this type of carbon is formed on the first protective film layer made of titanium oxide, the coefficient of friction is sufficiently reduced and the wear resistance is sufficiently improved. At the same time, the excellent corrosion resistance of the first protective film layer is fully exhibited, and the durability and corrosion resistance are sufficiently improved.

In addition, when the protective film layer made of an organic polymer compound and formed on the first protective film layer made of titanium oxide is formed by plasma polymerization, the protective film layer is , a monomer gas such as a hydrocarbon compound, a fluorine-based organic compound, and a silicon-based organic compound is plasma-polymerized using high frequency waves and deposited on the metal thin film layer. Examples of the monomer gas used to form this plasma-polymerized protective film layer include monomer gases of hydrocarbon compounds such as propane, ethylene, and propylene, monomer gases of fluorine-based organic compounds such as 02F4.03F6, and tetramethyl silane,
Monomer gases of silicon-based organic compounds such as octamethylcyclotetrasiloxane and hexamethyldisilazane are preferably used. Radicals of these organic compound monomer gases are generated by high frequency waves, and the generated radicals react and polymerize. It becomes a film. This radical is more likely to be generated when these organic compounds have a double bond or triple bond, are metal salt compounds with a fully bent element at the end, or have a functional group such as an O1l group. Therefore, those having these unsaturated bonds, totally bent elements, functional groups, etc. are more preferably used. In addition, when plasma polymerizing these 7-mer gases, argon gas,
When carrier gases such as helium gas and oxygen gas are present together, the monomer gas is deposited at a rate 3 to 5 times higher than when monomer gas is plasma-polymerized alone, so it is preferable to carry out the coexistence of these carrier gases. When coexisting with these carrier gases, the composition ratio is 1:20 in terms of volume ratio of the carrier gas to the 7-mer gas of the organic compound.
It is preferable that they coexist at a ratio of ~1:10; if the carrier gas is too small, the deposition rate will be reduced, and if it is too large, the monomer gas will be too small, which will impede the plasma integration reaction. Note that when using a monomer gas of a hydrocarbon compound, it is not preferable to use oxygen gas as a carrier gas because an oxidation reaction will occur if oxygen gas is used as a carrier gas.

When performing plasma polymerization, the higher the gas pressure and the higher frequency power, the faster the deposition rate of the plasma-polymerized protective film layer, but the monomer gas has a lower crosslinking density and is plasma-polymerized, resulting in a harder plasma-polymerized protective film layer. Moreover, when the gas pressure is lowered and the radio frequency power is increased, the deposition rate becomes slower, but a hard plasma polymerized protective film layer with a relatively high crosslinking density is obtained. However, if the gas pressure is low and the high frequency power is too high, the monomer gas will turn into powder and the plasma polymerization protection 'AtAR will not be formed. 0.03~3 W/cn! The gas pressure is preferably in the range of 0.01 to 1 torr, and the high frequency power is more preferably in the range of 0.05 to 2 W/cot. Moreover, it is more preferable to form such a plasma polymerized protective film layer on the electrode side to which high frequency waves are applied. The plasma-polymerized protective film layer of an organic compound deposited by plasma polymerization in this way is dense and has a small coefficient of friction, and is formed on the first protective film layer made of titanium oxide formed on the ferromagnetic metal thin film layer. In this way, the first protective film layer is prevented from coming into direct sliding contact with the magnetic head, etc., and the wear resistance is sufficiently improved. Therefore, when this kind of plasma-polymerized protective film layer is formed on the first protective film layer made of titanium oxide, the coefficient of friction is sufficiently reduced and the wear resistance is sufficiently improved, and at the same time The excellent corrosion resistance of the first protective film layer is also fully exhibited, and the durability and corrosion resistance are sufficiently improved.

In addition, when forming a protective film layer made of an organic polymer compound by sputtering, a resin with good heat resistance is sputtered with high frequency in the presence of argon gas etc. in a processing bath to deposit it on the magnetic layer. formed by As the resin used to form the protective film layer by such sputtering, resins with excellent heat resistance that do not soften or decompose at temperatures of 200°C or higher are preferably used, such as imide resins. ,
Silicone resins, phenolic resins, melamine resins, formalin resins, urea resins, furan resins, epoxy resins, and the like are preferably used.

When performing sputtering, gas pressure such as argon gas and high frequency power are set at 0.001 to 0.1 torr per square centimeter in order to improve the deposition rate and prevent decomposition of the polymer. High frequency power 0.1~2
It is preferably within the range of W/cA. The protective film layer made of a heat-resistant resin deposited by sputtering in this manner is dense and has a small coefficient of friction, and is placed on the first protective film layer made of titanium oxide formed on the ferromagnetic metal thin film layer. This prevents the first protective film layer from coming into direct sliding contact with the magnetic head, etc., and sufficiently improves wear resistance. Therefore, when a protective film layer made of this kind of heat-resistant resin is formed on the first protective film layer made of titanium oxide, the coefficient of friction is sufficiently reduced and wear resistance is sufficiently improved. At the same time, the excellent corrosion resistance of the first protective film layer is fully exhibited, and the durability and corrosion resistance are sufficiently improved.

The thickness of the protective film layer made of carbon or an organic polymer compound such as the plasma polymerized protective film layer and the heat-resistant resin protective film layer should be 50 Å or more in order to sufficiently improve wear resistance. is preferable, and if the total thickness with the first protective film layer made of titanium oxide is greater than 500, the spacing loss may increase and the electromagnetic conversion characteristics may deteriorate. It is preferable that the total thickness with the film layer is 500 Å or less.

The material for forming the ferromagnetic metal thin film layer is Co.

- Metals such as Fe and Ni, Co-Ni, Co-Cr.

Fe-Co, Fe-Co-Cr, Co'-Pt
, alloys such as Co-Ti, or oxides of these metals and alloys, and Co-P, Co-Ni -P
A ferromagnetic metal thin film layer made of these ferromagnetic materials is deposited on a substrate by means such as vacuum evaporation, ion blasting, sputtering, and plating.

In addition, as a substrate, plastic films such as polyester, polyimide, polyamide, polyvinyl chloride, and polycarbonate, as well as composite films in which carbon fiber, Cu, etc. are mixed into these plastic films, and C
All conventionally used materials such as non-magnetic totally refractive films such as U and Zn, aluminum plates and glass plates are preferably used, and as magnetic recording media,
Various forms of structures that come into sliding contact with magnetism include magnetic tapes using these plastic films as bases, magnetic disks and magnetic drums using discs made of plastic films, aluminum plates, glass plates, etc. as bases. includes.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 A polyester film with a thickness of 10 μm was loaded into a vacuum evaporation apparatus, and cobalt was heated and evaporated under a vacuum of 5×10 −′) and deposited on the polyester film by oblique incidence deposition at a deposition rate of 50 people/sec. A ferromagnetic metal thin film layer of cobalt with a thickness of 1000 nm was formed. After that, the inside of the vacuum chamber was evacuated to 5X10-6 Torr again, argon gas was introduced, and a voltage of 300W was applied in an argon gas atmosphere of 5X10-1-Torr to deposit TiO2 at a rate of 5 persons/sec. sputtered and made of TiO2 with a thickness of 10
A first protective film layer was formed. Subsequently, on this first protective film layer, a voltage of 300 W was applied in an argon gas atmosphere of 5×IO bow, and carbon was applied at 5 people/s.
Sputtering was performed at a deposition rate of EC to form a second protective film layer of carbon having a thickness of 100 mm. After that,
A ferromagnetic metal thin film layer 2, a first protective film layer 3,
A magnetic tape A was prepared in which the second protective film layer 4 was sequentially laminated.

Example 2 In forming the second protective film layer in Example 1, instead of forming the second protective film layer made of carbon, the inside of the vacuum chamber was again evacuated to 5×10-' Torr, and the inside of the vacuum chamber was C2F4 monomer gas was introduced at a rate of 10ml/flIin, and argon gas was introduced at a rate of 40ml/min.
was introduced at a ratio of Ti
Magnetic tape A was produced in the same manner as in Example 1, except that a second protective film layer made of a plasma polymerized protective film layer of 100 people was formed on the first protective film layer made of 02.

Comparative Example 1 A magnetic tape was produced in the same manner as in Example 1 except that the formation of the first protective film layer was omitted.

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 1 except that the formation of the second protective film layer was omitted.

Comparative Example 3 A magnetic tape was produced in the same manner as in Example 2 except that the formation of the first protective film Ji was omitted.

Comparative Example 4 A magnetic tape was produced in the same manner as in Example 1 except that the formation of the first protective film layer and the second protective film layer was omitted.

Regarding the magnetic tapes obtained in each example and comparative example,
Tested for durability and corrosion resistance. The durability test was conducted using a commercially available VTR tape deck at 2Q'C150%RH.
A still test was conducted on the magnetic tape obtained under the following conditions, and the still playback life was measured. In addition, in the corrosion resistance test, the obtained magnetic tape was left under conditions of 60°C and 90% RH for 7 days, the maximum magnetic flux density was measured, and the maximum magnetic flux density of the magnetic tape before being left was taken as 100%, and compared with this. The deterioration rate was investigated based on the value.

The table below shows the results.

Table [Effects of the Invention] As is clear from the above table, the magnetic tapes obtained in Examples 1 and 2 both had longer still playback lives than the magnetic tapes obtained in Comparative Examples 1 to 4. , the deterioration rate is small, and this shows that the magnetic recording medium obtained by the present invention has further improved durability and corrosion resistance.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged sectional view of a magnetic tape obtained by the present invention. DESCRIPTION OF SYMBOLS 1... Polyester film (substrate), 2... Ferromagnetic total refraction thin film layer, 3... First protective film layer, 4... Second
protective film layer, A...magnetic tape (magnetic recording medium) first
figure

Claims (1)

[Claims] 1. A ferromagnetic metal thin film layer made of a metal or an alloy thereof is formed on a substrate, and a first protective film layer made of titanium oxide is provided on the surface of this ferromagnetic metal thin film layer, A magnetic recording medium 2 characterized in that a second protective film layer made of carbon or an organic polymer compound containing at least carbon atoms is further provided on the first protective film layer made of titanium oxide. The magnetic recording medium 3 according to claim 1, further comprising a hydrogen atom in the second protective film layer made of an organic polymer compound formed on the organic polymer compound provided on the first protective film layer made of titanium oxide. A magnetic recording medium 4 according to claim 1, wherein the second protective film layer made of a polymer compound further contains hydrogen atoms and silicon atoms, and the magnetic recording medium 4 is provided on the first protective film layer made of titanium oxide. The magnetic recording medium according to claim 1, further comprising a fluorine atom in the second protective film layer made of an organic polymer compound.