JPS6089821A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium to which a protective film is securely joined and which has running durability and corrosion resistance by forming a thin ferromagnetic metallic film on a base body and depositing phosphate or the salt thereof on the surface of the thin film then forming an org. high polymer protective film thereon. CONSTITUTION:A thin ferromagnetic metallic film 8 consisting of a metal such as Co, Fe, Ni or the alloy thereof is formed on a base body 1 consisting of a polyester film, etc. A soln. of phosphate such as polyoxyethylene alkyl ether phosphate or the salt thereof is coated on the film 8 and is dried to form a film 9 to join securely the protective layer 10 to be provided thereon so that the peeling of said layer 10 from the magnetic film 8 or the like is prevented. The layer 10 is formed by coating and drying a soln. of a vinyl chloride/vinyl acetate copolymer, etc. or by a plasma polymn. method, etc. of hydrocarbon, fluorin org. compd. or silicon org. compd. The durability and corrosion resistance are thus improved without affecting adversely the electromagnetic conversion characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium having a ferromagnetic metal thin film layer as a magnetic recording layer, and an object thereof is to provide the above-mentioned magnetic recording medium having excellent durability and film resistance. It's about doing.

A magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film layer is
It is made by depositing lightning conductors, metals, or their alloys on a base film using a vacuum sensor, etc., and has characteristics suitable for high-density recording, but on the other hand, friction with the surface magnetic head is large, resulting in wear and tear. There is an EIt point where magnetic properties such as maximum magnetic flux density deteriorate due to gradual oxidation in the air.

For this reason, attempts have been made to improve durability and corrosion resistance by forming various protective film layers on the ferromagnetic metal thin film layer, and by dissolving a resin with good film properties in a solvent. It has been proposed to provide a protective film layer made of an organic polymer compound on a ferromagnetic metal thin film layer by coating it on the magnetic metal thin film layer, or, in recent years, by using methods such as plasma polymerization and sputtering. .

However, the protective film layer made of these organic polymer compounds does not have good adhesion to the ferromagnetic metal thin film layer, and the protective film layer peels off or breaks in a relatively short period of time due to sliding contact with the magnetic head. Under high temperature and high humidity conditions, the ferromagnetic metal thin film layer under the protective film layer may corrode in a relatively short time or the protective film layer may peel off, and durability and corrosion resistance have not yet been sufficiently improved.

As a result of various studies in view of the current situation, the inventor first deposited a phosphoric acid ester or a salt thereof on the surface of a ferromagnetic metal thin film layer, and then coated the resin with the phosphoric acid ester or salt thereof. When a protective film layer made of an organic polymer compound is formed by dissolving it in a solvent and applying it, plasma polymerizing an organic compound monomer gas, or sputtering a heat-resistant resin,
This phosphoric ester or its salt is strongly bonded to the surface of the ferromagnetic metal thin 1* layer and has good adhesion to the protective film layer made of the organic polymer compound described above. The present inventors have discovered that the protective film layer made of the organic polymer compound described above can be firmly adhered to the ferromagnetic metal thin film layer through the ferromagnetic metal thin film layer, and the durability and corrosion resistance can be sufficiently improved.

As the phosphoric acid ester or its salt used in this invention, polyoxyethylene alkyl ether phosphoric acid or its salt, alkyl phosphoric acid ester or its salt, etc. are preferably used. It has good properties and binds firmly to metal surfaces, and is also compatible with organic polymer compounds. Therefore”
This kind of phosphoric acid ester or its salt is well adhered to a ferromagnetic metal thin film layer made of a ferromagnetic metal to form a test material, and a protective film layer made of an organic polymer compound is formed on this. The protective film layer made of the organic polymer compound is also compatible with the protective film layer made of these organic polymer compounds. Strong adhesion with excellent adhesive properties. As a result, the adhesion of the protective film layer made of an organic polymer compound to the ferromagnetic metal thin film layer is improved, and even under high temperature and humidity conditions, the ferromagnetic metal thin film layer of the protective film N) will not corrode or Protection I! ii! The shells will not peel off, and the durability and corrosion resistance will be sufficiently improved.

Such a phosphoric acid ester or its salt is dissolved in an appropriate solvent such as toluene, and the ferromagnetic metal thin film layer is immersed in the solution obtained by dissolution, or the solution is applied to the surface of the ferromagnetic metal thin film layer. It is deposited on the ferromagnetic metal thin film layer by coating or spraying. It is preferable that the amount of the coating be within the range where 2 to 500 test subjects are formed on the ferromagnetic metal thin film layer.If the film thickness is thinner than 28, the desired effect cannot be obtained, The thicker the film, the lower the adhesive strength. In this way, it is preferable to apply the coating amount within a range that will cover 2 to 500 subjects, and 5 to 10
It is more preferable to apply the coating within a range in which a coating of 0 people is formed.

On the surface of the ferromagnetic metal i-film layer coated with such phosphoric acid esters or salts thereof, a protective layer consisting of an organic polymer compound is further deposited via these phosphoric acid esters or salts thereof. When the 2-layer is formed by dissolving the resin in a solvent and applying it, the 2-layer is made of vinyl chloride.
A resin with good film properties such as vinyl acetate copolymer, polyvinyl butyral resin, cellulose resin, polyurethane resin, polyester resin, ABS resin, methyl methacrylate, etc. is dissolved in a suitable ta-containing solvent to form a ferromagnetic material. It is formed by coating on a metal thin film layer and drying it. Protection 1 made of resin thus formed! The layer has good film properties, self-lubricating properties, and extremely hardness. Therefore, the layer made of this resin forms a ferromagnetic metal thin film layer through phosphoric acid ester or its salt. When formed above, the adhesion to the ferromagnetic metal thin film 1i is also good, and IT wear resistance and corrosion resistance are improved. The thickness of the protective film layer made of such a resin is preferably within the range of 300 to 3000, and 11! ;l! If the thickness is too thin, the natural and corrosion-resistant effects of this protective film layer will not be fully exhibited, and if it is too thick, the spacing loss will be too large and will not adversely affect the electromagnetic conversion characteristics.

In addition, when a plasma-polymerized protective film layer is formed by plasma polymerization of monomer gas of an organic compound, monomer gas of hydrocarbon compounds, ), thread organic compounds, silicon-based organic compounds, etc. The vj acid ester or its salt is precipitated on the deposited ferromagnetic metal thin film layer by plasma polymerization using high frequency waves, thereby forming a ferromagnetic metal thin film layer. The monomer gas used to form this plasma polymerization protection 11J includes, for example,
Monomer gas of hydrocarbon compounds such as coban, ethylene, propylene, monomer gas of 7-based organic compounds such as C2F4, C3F6, and tetramethylsilane,
Monomer gases of silicon-based organic compounds such as octamethylcyclotetrasiloxane and hexamethyldisilazane are preferably used, and these organic compound monomer gases generate radicals by high frequency, and the generated radicals react. Polymerizes to form a film. This radical is more likely to be generated when these organic compounds have double bonds or triple bonds, are metal salt compounds with a metal element at the end, or have functional groups such as OH groups. , those having these unsaturated bonds, metal elements, functional groups, etc. are more preferably used. In addition, when plasma polymerizing these 7-mer gases, if a carrier gas such as argon gas, helium gas, or oxygen gas is present, the monomer gas will be deposited at a rate 3 to 5 times faster than when monomer gas is plasma polymerized alone. It is preferable to use these carrier gases together. When coexisting with these carrier gases, the composition ratio is expressed as a ratio of the carrier gas to the 7-mer gas of the organic compound.
It is preferable to coexist within a range of 20 to 1; if the carrier gas is too small, the carrier gas will decrease the carrier gas, and if it is too large, the monomer gas will be too small, which will interfere with the plasma polymerization reaction. Note that when using a 7-mer 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 the high frequency output, the higher the deposition rate, but on the other hand, the monomer gas is plasma polymerized with a relatively low molecular weight, making it difficult to obtain a hard protective film layer. If the gas pressure is lowered and the high frequency output is increased, the deposition rate will be slower, but at the same time a relatively hard protective film layer made of polymer will be obtained. However, if the gas pressure is lowered and the high frequency output is kept high, the monomer gas will turn into powder. If the plasma polymerized protective film layer is not formed, the gas pressure should be reduced to 0.
．． Within the range of 0.03 to 5 torr, and the high frequency output is 0.03
It is preferably within the range of ~l W/cot, with a gas pressure of 0.05-1 Torr and an 11-frequency output of 0.0
More preferably, it is within the range of 5 to 0.3 W/cot. The plasma-polymerized protective film layer of an organic compound that is deposited and formed by plasma polymerization in this way is dense and has a small coefficient of friction. When formed on the layer, it has good adhesion to the ferromagnetic metal thin film layer and further improves wear resistance and corrosion resistance. II! of such a plasma polymerized protective film of an organic compound j-! ! The thickness is
It is preferably within the range of 20 to 1000 people. If the film thickness is too thin, the durability and corrosion resistance effects of this protective film layer will not be fully exhibited, and if it is too thick, the spacing loss will be too large and electromagnetic conversion No adverse effect on characteristics.

Furthermore, when a protective film layer made of a heat-resistant resin is formed 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 ferromagnetic metal thin film layer. formed by The resin used to form the protective film layer by such sputtering is preferably a resin with excellent heat resistance that does not soften or decompose at temperatures of 200'C or higher; A material that softens or decomposes during sputtering is not preferable because it will decompose during sputtering. Examples of such heat-resistant resins include polyimide resins, fluorine resins, silicone resins, phenol resins, melamine resins, pomarine resins, urea resins, furan resins, and epoxy resins. Examples include Kapton, silicone resin,
Examples include Teflon.

When performing sputtering, the gas pressure such as argon gas and the output of high frequency are set to 0.1-0.001 torr to prevent heat-resistant resin) W etc.
Preferably, the high frequency output is within the range of 0.1 to 5 W/cnl. The protective film layer made of heat-resistant resin deposited by sputtering in this way is dense and has a small coefficient of friction. When formed as a thin metal layer, it has good adhesion with the ferromagnetic thin metal layer, and its abrasion resistance and corrosion resistance are further improved.A protective film made of such a heat-resistant resin The thickness of the layer is preferably within the range of 20 to 1000. If the film II is too thin, the durability and corrosion resistance of the αI film layer will not be fully demonstrated, and if it is too thick, it will cause spacing loss. becomes too large and does not adversely affect electromagnetic conversion characteristics.

Materials for forming the ferromagnetic metal thin film layer include Co, Fe, and N.
i, Co-Ni alloy, Co-Cr alloy, Co-P alloy,
Ferromagnetic materials such as Co-JJi-P alloy are used, and ferromagnetic metal thin film layers made of these ferromagnetic materials are formed by vacuum deposition,
It is deposited on the substrate by means such as ion blasting, sputtering, and plating.

In addition, as magnetic recording media, polyester film,
Various types of structures that come in close contact with magnetic heads, such as magnetic tapes based on synthetic resin films such as polyimide films, magnetic disks and magnetic drums based on disks and drums made of synthetic resin films, aluminum and glass plates, etc. includes.

Next, embodiments of the invention will be described.

Example 1 A polyester film with a thickness of lOμ was loaded into a vacuum deposition apparatus, and cobalt was heated and thermally evaporated under a vacuum of lX10-5 torr to form a ferromagnetic metal thin film layer of cobalt with a thickness of 800μ on the polyester film. was formed. Next, a 065% by weight isopropyl alcohol solution of Blysurf A-212C (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene alkyl ether phosphoric acid) was applied to this, and dried to a thickness of 1.
A coating consisting of Blysurf A-212C to 00 was formed. Next, a ferromagnetic metal thin film layer was formed using the plasma processing apparatus shown in FIG.
A monomer gas of tetramethylsilane is introduced for 100 seconds from the gas introduction pipe 4 attached to the processing tank 2 through the cellar 1 to run along the circumferential side of the cylindrical can 3 disposed inside the processing tank 2.
ecm, plasma polymerization was carried out at a gas pressure of 0.5 Torr, a high frequency output of electrode 5 of 0.3 W/Cl, and a running speed of polyester film l of lrn/min.
A plasma polymerized protective layer of 200 times was formed. Thereafter, a magnetic tape A is prepared by cutting into a predetermined size and sequentially laminating a ferromagnetic metal thin film layer 8, a phosphoric acid ester coating 9, and a plasma polymerized protective film layer 10 on a polyester film l as shown in FIG. I made it. In addition, 6 in the figure
7 is an exhaust system for reducing the pressure inside the processing tank 2, and 7 is a high frequency power source for applying high frequency to the electrode 5.

Example 2 In Example 1, 0.5 of Blysurf A-212C
Instead of the weight% isopropyl alcohol solution, Erucin 19M (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., alkyl phosphate ester salt)
A magnetic tape was produced in the same manner as in Example 1 except that a 0.5% by weight isopropyl alcohol solution was used to form a 200-thick 11-layer film made of 19M ζErn.

Example 3 In the formation of the plasma-polymerized protective film layer in Example 2, plasma polymerization was carried out using tetramethylsilane monomer gas at a high frequency output of 0.3 W/aA from electrode 5 and a running speed of polynisdel film 1 of 1+n/min. and jv 150
A magnetic tape was produced in the same manner as in Example 1, except that a human plasma polymerization protection 1 pattern 1i was formed.

Example 4 In the formation of the plasma polymerization protection 1 dust layer in Example 1, instead of the monomer gas of tetramethylsilane, a monomer gas of ζ and zolopane was introduced into the treatment tank 2 at a flow rate of 100 sec, and the gas pressure was 0. .51~-1, high frequency output of electrode 5 0, 3 W/a, polyester film l
Plasma polymerization was carried out at a running speed of 1 m/min, and the thickness was 1 m/min.
A magnetic tape was made in the same manner as in Example 1, except that 80 plasma polymerization bonds were formed.

Example 5 Plasma polymerization protection as in Example 1! Instead of forming a layer ζ, the gas pressure of argon gas is 3 x ■ 0 bow 1 - with Kapton as a target on the electrode 5 in the processing tank 2.
A magnetic tape was produced in the same manner as in Example 1, except that sputtering was carried out with the high frequency output of electrode 5 set to IW/ail to form a protective film layer of 150 Kapton thick.

Example 6 Instead of forming the plasma polymerized protective film layer in Example 1, 5ffiit% of V AGH (vinyl chloride-vinyl acetate-vinyl alcohol copolymer manufactured by U, C, C Company) was used.
A magnetic tape was prepared in the same manner as in Example 1, except that methyl isobutyl ketone-toluene was coated and dried to form a protective film layer of 800 V AGH in thickness.

Comparative Example 1 In Example 1, 0 of Plysurf A-212C,
A magnetic tape was prepared in the same manner as in Example 1 except that the isopropyl alcohol was omitted.

Comparative Example 2 In Example 2, Ot5ffi amount% of Nilenone 19M
A magnetic tape was produced in the same manner as in Example 2, except that the application of the isopropyl alcohol solution was omitted.

Comparative Example 3 In Example 3, Plysurf A-212C (7)
A magnetic tape was prepared in the same manner as in Example 3 except that the application of the 0.5% by weight isopropyl alcohol solution was omitted.

Comparative Example 4 In Example 4, 0.5 of Plysurf A-212C
A magnetic tape was prepared in the same manner as in Example 4 except that the application of the wt% isopropyl alcohol solution was omitted.

Comparative Example 5 In Example 5, Plysurf A-2 1 2C-0
．． A magnetic tape was prepared in the same manner as in Example 5 except that the application of the 5ffiit% isopropyl alcohol solution was omitted.

Comparative Example 6 In Example 6, 0.5 of Plysurf A-212C
A ζ magnetic tape was prepared in the same manner as in Example 6 except that the application of the wt % isopropyl alcohol solution was omitted.

The adhesive strength of the magnetic tapes obtained in each Example and each Comparative Example was measured, and the durability and corrosion resistance were tested.

The adhesive strength was measured by performing a peel test using a peel tester, and the durability test was performed by measuring the still life of the magnetic tape obtained using a VHS type video tape recorder. In addition, corrosion resistance tests were conducted on the obtained magnetic tape at 60°C and 90°C.
The maximum magnetic flux density was measured after being left under the condition of 0% RH for 7 days, and the deterioration rate was compared with the maximum magnetic flux density of the magnetic tape before being left as 100%.

The table below shows the results.

As is clear from the above table, the (d tapes (Examples 1 to 6) obtained in this invention have stronger adhesive strength and longer still life than the magnetic tapes obtained in Comparative Examples 1 to 6. Therefore, the magnetic recording medium obtained by the present invention has good adhesion to the ferromagnetic metal thin film layer of the protective first layer made of an organic polymer compound, and as a result, has excellent durability and It can be seen that the corrosion resistance has been further improved.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an example of a plasma processing apparatus used in forming a plasma polymerized protective film layer, and FIG. 2 is a partially enlarged sectional view of a magnetic tape obtained by the present invention. ■...Polyester film (substrate), 8...Ferromagnetic metal thin film director, 9...Phosphate ester coating, IO...
・Plasma polymerized protective film layer (organic polymer compound protective film layer)
, A... Magnetic tape (magnetic recording medium) patent applicant Hitachi Maxell Co., Ltd. Agent Takaoka-Haru Figure 1 A Figure 2

Claims (1)

[Claims] 1. A ferromagnetic metal thin film layer made of a metal or an alloy thereof is formed on a substrate, a phosphoric acid ester or its salt is deposited on the surface of this ferromagnetic metal thin layer, and an organic polymer compound is further coated on the surface of the ferromagnetic metal thin layer. A magnetic recording medium characterized by having a protective film layer and a structure.