JP2581090B2 - Magnetic recording media - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording medium such as a magnetic tape and a magnetic disk, and more particularly to a magnetic recording medium using a perfluoroalkylamine carboxylate as a lubricant. Things.

[Summary of the Invention]

The present invention provides a magnetic recording medium having a magnetic layer on a non-magnetic support, wherein the perfluoroalkylamine carboxylate is used as a lubricant to provide excellent running properties even under various use conditions. An object of the present invention is to provide a magnetic recording medium exhibiting abrasion resistance, durability and the like.

[Conventional technology]

For example, a so-called metal thin-film type magnetic recording medium in which a ferromagnetic metal material is deposited on a non-magnetic support by a method such as vapor deposition, and this is used as a magnetic layer, or very fine magnetic particles and a resin binder are used. In a so-called coating type magnetic recording medium in which a magnetic paint containing a magnetic material is coated on a non-magnetic support and the magnetic layer is used as a magnetic layer, the magnetic layer surface has extremely good smoothness. There are many problems such as a substantial contact area with the member, a large coefficient of friction, a tendency for adhesion (so-called sticking) to occur, and poor running and durability.

Therefore, it has been studied to use various lubricants in order to improve these problems. Conventionally, higher fatty acids or esters thereof are internally added to the magnetic layer of the magnetic recording medium or top coated. Attempts have been made to reduce the coefficient of friction.

Incidentally, lubricants used for magnetic recording media are required to have extremely strict characteristics due to their properties, and it is difficult for conventional lubricants to cope with them.

In other words, the lubricant used for the magnetic recording medium has an excellent low-temperature characteristic so that a predetermined lubricating effect is ensured even when used in a cold region, and the spacing with the magnetic head becomes a problem. It is required to be able to be applied thinly, to exhibit sufficient lubricity even in such a case, to be able to withstand long-term or long-term use, and to maintain the lubricating effect.

However, higher fatty acids and their esters, which have been conventionally used, tend to freeze and solidify under low-temperature conditions such as 0 ° C. or lower, impairing the function as a lubricant, or lacking long-term durability. is there.

[Problems to be solved by the invention]

As described above, in the field of magnetic recording media, practical properties such as running properties, abrasion resistance, and durability remain unsatisfactory due to insufficient capacity of the lubricant used.

Accordingly, the present invention provides a magnetic recording medium that maintains excellent lubricity under various use conditions, maintains a lubricating effect for a long period of time, and has excellent running properties, wear resistance, durability, and the like. It is intended for.

[Means for solving the problem]

The present inventors have conducted intensive studies to achieve the above object and found that a compound of a carboxylic acid and a perfluoroalkylamine salt was suitable for this purpose, and completed the present invention. Things.

That is, the magnetic recording medium of the present invention is a magnetic recording medium having at least a magnetic layer on a non-magnetic support, (Where n is an integer of _{1 to 3} , at least one of R ₁ , R ₂ , and R ₃ is a perfluoroalkyl group having 3 or more carbon atoms, and R is a hydrocarbon group). It is characterized by having a perfluoroalkylamine carboxylate.

The carboxylic acid perfluoroalkylamine salt of the present invention is synthesized from a carboxylic acid and a perfluoroalkylamine.

Here, the number n of the carboxylic acid and the perfluoroalkylamine salt in the above formula is preferably 1 to 3. When n is 0, no lubricant is formed. When n is 4 or more, practical problems such as handling of the lubricant occur. For example, it becomes difficult to apply a very thin coating.

In the above formula, at least one of R ₁ , R ₂ , and R ₃ constituting the perfluoroalkylamine salt is preferably a perfluoroalkyl group. Therefore, the perfluoroalkylamine salt takes one of a monoperfluoroalkylamine salt, a diperfluoroalkylamine salt, and a tripperfluoroalkylamine salt. In the case of a monoperfluoroalkylamine salt or a diperfluoroalkylamine salt, the group other than the perfluoroalkyl group is hydrogen or a normal alkyl group. The perfluoroalkyl group constituting the perfluoroalkylamine salt preferably has 3 or more carbon atoms. When the carbon number n of the perfluoroalkyl group is less than 3,
The lubrication effect by introducing fluorine is insufficient. There is no particular upper limit, but if the number of carbon atoms exceeds 12, a problem arises in handling as a lubricant. The perfluoroalkyl group may be linear or branched.

Further, R in the above formula is a fatty acid, an alicyclic ring, or an aromatic hydrocarbon group, and may be any of linear, branched, saturated, unsaturated, and the like. You may. This R may be substituted by fluorine. The hydrocarbon group of R preferably has 3 or more carbon atoms.

The magnetic recording medium of the present invention has the above perfluoroalkylamine carboxylate as a lubricant.

Here, as the magnetic recording medium to which the present invention is applied,
First, there is a so-called coating type magnetic recording medium in which a magnetic coating is formed as a magnetic layer by applying a magnetic paint to the surface of a non-magnetic support.

In the coating type magnetic recording medium, any of conventionally known magnetic powders, resin binders, and the like constituting the nonmagnetic support and the magnetic coating film can be used, and are not limited at all.

For example, as the non-magnetic support, a polymer support formed of a polymer material represented by polyesters, polyolefins, cellulose derivatives, vinyl resins, polyimides, polyamides, polycarbonates and the like And a metal substrate made of an aluminum alloy, a titanium alloy or the like, a ceramic substrate made of alumina glass or the like, a glass substrate, or the like. The shape is not limited at all, and may be any shape such as a tape shape, a sheet shape, and a drum shape. Further, in order to control the surface properties, the non-magnetic support may be subjected to a surface treatment for forming fine irregularities.

As the magnetic powder, γ-Fe ₂ O ₃ , cobalt-coated γ-Fe ₂
Ferromagnetic iron oxide particles such as O ₃ , ferromagnetic chromium dioxide particles, ferromagnetic metal particles composed of metals such as Fe, Co, Ni, and alloys containing these, hexagonal plate-like hexagonal ferrite fine particles, etc. Is exemplified.

As the resin binder, vinyl chloride, vinyl acetate, vinyl alcohol, vinylidene chloride, acrylate,
Examples thereof include polymers such as methacrylic acid esters, styrene, butadiene, and acrylonitrile, or copolymers of two or more of these, polyurethane resins, polyester resins, epoxy resins, and the like. These binders include:
In order to improve the dispersibility of the magnetic powder, a hydrophilic polar group such as a carboxylic acid group, a carboxyl group, or a phosphoric acid group may be introduced.

In addition to the magnetic powder and the resin binder described above, a dispersant, an abrasive, an antistatic agent, a rust inhibitor, and the like may be added to the magnetic coating film as additives.

As a method for retaining the carboxylic acid perfluoroalkylamine salt in such a coating type magnetic recording medium,
As shown in FIG. 1, a method of internally adding a magnetic layer (2) constituting a magnetic coating film formed on a nonmagnetic support (1),
As shown in FIG. 2, there is a method of applying a top coat (3) on the surface of the magnetic layer (2) or a combination of these two methods.

When a perfluoroalkylamine carboxylate is internally added to the magnetic coating film, the resin binder is added to 100 parts by weight.
It is added in the range of 0.2 to 20 parts by weight.

When the carboxylic acid perfluoroalkylamine salt is top-coated on the surface of the magnetic coating film, the coating amount is 0.5
Is preferably from -100 mg / m ^2, and more preferably 1 to 20 mg / m ^2.

When the carboxylic acid perfluoroalkylamine salt is top-coated, as a method of applying the solution, a solution obtained by dissolving the carboxylic acid perfluoroalkylamine salt in a solvent is applied or sprayed, or vice versa. What is necessary is just to immerse the magnetic recording medium in the solution.

The present invention can also be applied to a so-called metal thin film type magnetic recording medium in which a magnetic coating is formed as a magnetic layer by a method such as vapor deposition of a magnetic paint on the surface of a non-magnetic support. Further, this metal thin film type magnetic recording medium can be applied to a magnetic recording medium having a configuration in which an underlayer is interposed between a nonmagnetic support and a magnetic layer.

Also in this case, the non-magnetic support and the metal magnetic thin film of the applicable metal thin film type magnetic recording medium are not limited at all, and any conventionally known ones can be used.

For example, the same non-magnetic support as the above-mentioned coating type magnetic recording medium can be used. In this case, when a substrate having a composition such as an Al alloy plate or a glass plate is used for the non-magnetic support, an oxide film such as alumite treatment or a Ni-P film is formed on the substrate surface to harden the surface. You may make it.

The metal magnetic film is formed as a continuous film by PVD techniques such as plating, sputtering, and vacuum deposition.
e, Co, metals such as Ni, Co-Ni alloys, Co-Pt alloys, Co
-Ni-Pt alloy, Fe-Co alloy, Fe-Ni alloy, Fe-Co
-Ni alloy, Fe-Ni-B alloy, Fe-Co-B alloy, Fe
Examples thereof include an in-plane magnetization recording metal magnetic thin film made of a -Co-Ni-B alloy or the like, and a perpendicular magnetization recording metal magnetic thin film such as a Co-Cr alloy thin film or a Co-O thin film.

In particular, in the case of an in-plane magnetized recording metal magnetic thin film, a base film of a low-melting nonmagnetic material such as Bi, Sb, Pb, Sn, Ga, In, Ge, Si, or Tl is formed on a nonmagnetic support in advance. Each metal magnetic material is deposited or sputtered from the vertical direction to diffuse these low-melting non-magnetic materials into the magnetic metal thin film, thereby eliminating orientation and ensuring in-plane isotropy and improving coercive force. You may do so.

When a hard disk as described above is used, a hard protective film such as a carbon film, a diamond-like carbon film, a chromium oxide film, and a SiO ₂ film may be formed on the surface of the metal magnetic thin film.

Further, the underlayer interposed between the nonmagnetic support and the magnetic layer is formed by electron beam evaporation of Bi or the like.

As a method for retaining the perfluoroalkylamine carboxylate in such a metal thin film type magnetic recording medium, as shown in FIG. 2, a method of top-coating (3) a metal magnetic thin film surface or the protective film surface is used. No. In this case, the coating amount of the carboxylic acid perfluoroalkyl amine salt, again is preferably 0.5 to 100 mg / m ^2, more preferably 1 to 20 mg / m ^2.

The above carboxylic acid perfluoroalkylamine salt is
Although it may be used alone as a lubricant for magnetic recording media,
It may be used in combination with a conventionally known lubricant. Alternatively, it can be used in combination with a perfluoroalkyl carboxylic acid ester, a carboxylic acid perfluoroalkyl ester, a perfluoroalkyl carboxylic acid perfluoroalkyl ester, or a derivative thereof.

Further, in order to cope with more severe conditions and maintain the lubricating effect, an extreme pressure agent may be used in combination at a weight ratio of about 30:70 to 70:30.

The extreme pressure agent reacts with the metal surface due to the frictional heat generated when partial metal contact occurs in the boundary lubrication region, and performs a friction / wear prevention effect by forming a reaction product film. Any of phosphorus-based extreme-pressure agents, sulfur-based extreme-pressure agents, halogen-based extreme-pressure agents, organometallic-based extreme-pressure agents, and complex-type extreme-pressure agents can be used.

Further, in addition to the above-mentioned lubricant and extreme pressure agent, a rust preventive may be used in combination as needed.

As the rust inhibitor, any one which is usually used as a rust inhibitor for this type of magnetic recording medium can be used, for example, phenols, naphthols, quinones, heterocyclic compounds containing a nitrogen atom, oxygen atoms And heterocyclic compounds containing a sulfur atom.

The rust inhibitor may be mixed and used as a lubricant containing a perfluoroalkylamine carboxylate, but as shown in FIG. 3, a magnetic layer (2) is formed on a non-magnetic support (1). The effect is high if the rust preventive layer (4) is applied to the upper portion and then the lubricant layer (5) is applied, and the lubricant is applied in two or more layers.

By the way, in any of the above-mentioned coating type magnetic recording medium and metal thin film type magnetic recording medium, in addition to the magnetic coating film and the metal magnetic thin film as the magnetic layer, a back coat layer, an undercoat layer, etc. May be formed.

For example, the back coat layer is formed by adding a carbon-based fine powder for imparting conductivity or an inorganic pigment for controlling surface roughness to the same resin binder as the magnetic coating film.

In the present invention, the above-mentioned perfluoroalkylamine carboxylate may be added to the back coat layer as a lubricant internally or by a top coat.
Alternatively, various combinations such as internal addition of a perfluoroalkylamine carboxylate as a lubricant and top coating to the magnetic coating film, the metal magnetic thin film and the back coat layer are also possible.

[Action]

A perfluoroalkylamine salt of a carboxylic acid synthesized from a carboxylic acid and a perfluoroalkylamine exhibits a good lubricating action and reduces the friction coefficient. Further, this lubricating action is not impaired even under severe conditions such as low temperature.

In the magnetic recording medium using the perfluoroalkylamine carboxylate as a lubricant, the running property is improved and the durability is improved by the lubricating action of the perfluoroalkylamine carboxylate.

〔Example〕

Hereinafter, specific examples of the present invention will be described,
It goes without saying that the present invention is not limited to this embodiment.

First, Table 1 shows the synthesized products of perfluoroalkylamine carboxylate used in this example.

Using the composites shown in Table 1, the following magnetic recording media were produced.

First, an example was applied to a coating type magnetic recording medium.

Example 1 100 parts by weight of Co-coated γ-Fe ₂ O ₃ Vinyl chloride-vinyl acetate copolymer (VAGH manufactured by UCC)
10.5 parts by weight Polyurethane resin (M-5033 manufactured by Nippon Polyurethane)
10.5 parts by weight Carbon (antistatic agent) 5 parts by weight Lecithin (dispersant) 1 part by weight Methyl ethyl ketone 150 parts by weight Methyl isobutyl ketone 150 parts by weight The above composition was used as a basic composition, and the basic composition was used as a lubricant in Table 1. 1.5 parts by weight of Synthetic Compound 1 therein was added, mixed for 24 hours in a ball mill, taken out through a filter, further added with 4 parts by weight of a curing agent, and stirred for 30 minutes. This magnetic paint was applied on a polyethylene terephthalate base having a thickness of 12 μm so that the thickness after drying became 5 μm, and after orientation in a magnetic field, dried and wound up. This was calendered and then cut into 1/2 inch widths to produce sample tapes.

Example 2 to Example 6 In Example 1, a sample tape was produced in the same manner as in Example 1 except that Synthetic 2 to Synthetic 6 in Table 1 were added instead of Synthetic 1. .

Comparative Example 1 In Example 1, a sample tape was prepared in the same manner as in Example 1, except that nothing was added as a lubricant instead of the synthetic product 1.

For each sample tape prepared as described above, a temperature of 25 ° C. and a relative humidity of 60% and a temperature of 40 ° C. and a relative humidity of 80
%, The friction coefficient and the stick-slip were measured before and after aging. Table 2 shows the results.

As is clear from Table 2 above, the use of the perfluoroalkylamine carboxylate as a lubricant provided very good results without deterioration in friction coefficient and stick-slip even under various conditions.

Next, an embodiment applied to a metal thin film type magnetic recording medium (with a hard disk and a base film) will be described.

Example 7 First, an Al-Mg alloy substrate (1.5 mm thick, 95 m outer diameter) on which a 15 μm thick Ni-P plating layer was formed as a nonmagnetic metal underlayer.
m, inner diameter 25 mm), and apply a pressure of 1 × 10
Bi was deposited by electron beam evaporation under the conditions of ^-5 Torr and a substrate temperature of 150 ° C. to form a low-melting metal underlayer having a thickness of 200 °.

Next, Co was electron beam deposited on the underlayer under the conditions of a pressure of 1 × 10 ⁻⁵ Torr and a substrate temperature of 150 ° C.
A metal magnetic thin film was formed, and a carbon protective film was formed on the metal magnetic thin film by a vacuum evaporation method.

Lastly, a lubricant indicated by synthetic substance 1 in Table 1 was applied to the surface of the carbon protective film to produce a sample disk.

Examples 8 to 12 Compound 1 used as a lubricant in Example 7 was replaced with Compound 2
A sample disk was prepared in the same manner as in Example 7 except that the composition disk was changed to.

For each of the sample disks obtained as described above, the friction coefficient after 20,000 times was examined by a contact start / stop (CSS) test. Table 3 shows the results.

As shown in Table 3, each sample disk with a carbon protective film formed on the surface of the metal magnetic thin film and using the compound shown in Table 1 as a lubricant on top of it has excellent CSS characteristics and improved durability. You can see that it was done.

Further, an embodiment applied to a metal thin film type magnetic recording medium (floppy disk, no base film) will be described.

Example 13 Co was applied to a 14 μm-thick polyethylene terephthalate film by an oblique evaporation method to form a ferromagnetic metal thin film having a thickness of 1000 °.

Next, a solution obtained by dissolving Compound 1 in Table 1 in a mixed solvent of Freon and ethanol was applied to the surface of the ferromagnetic metal thin film so that the application amount was 5 mg / m ^2, and the width was 8 mm. This was cut to produce a sample tape.

Examples 13 to 18 In Example 12, the compound 1 in Table 1 used as a lubricant was changed to Compounds 2 to 6, and the others were the same as in Example 12.
A sample tape was produced in the same manner as described above.

For each sample disk manufactured as described above, the temperature was 25 ° C, the temperature was 60%, the temperature was -5 ° C, and the temperature was
The friction coefficient, still durability and shuttle durability at 40 ° C and 30% humidity were measured. For the still durability, the decay time of the output to −3 dB in the pause state was evaluated. Shuttle durability was evaluated by the number of shuttles required until the output decreased by 3 dB after running the shuttle for 2 minutes each time. As Comparative Example 3, a blank disk using no lubricant was also measured. The results are shown in Tables 4 and 5.

As is clear from Tables 4 and 5, by using perfluoroalkylamine carboxylate as a lubricant, the coefficient of friction, still durability, shuttle durability, etc. can be extremely reduced without deterioration even under various conditions. Good results were obtained.

〔The invention's effect〕

As is clear from the above description, the magnetic recording medium of the present invention is a compound having extremely excellent lubricity, and has a carboxylic acid perfluoroalkylamine salt useful as a lubricant as a lubricant. Therefore, lubricity can be maintained under any use conditions, and the lubricity can be maintained for a long period of time.

Therefore, the magnetic recording medium of the present invention has excellent running properties, wear resistance, and durability.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part showing one configuration example of a magnetic recording medium to which the present invention is applied. FIG. 2 is an enlarged sectional view of a main part showing another example of the configuration of the magnetic recording medium to which the present invention is applied. FIG. 3 is an enlarged sectional view of a main part showing still another configuration example of the magnetic recording medium to which the present invention is applied. 1. Non-magnetic support 2. Magnetic layer

Claims (1)

(57) [Claims] 1. A magnetic recording medium having at least a magnetic layer on a non-magnetic support, comprising: (In the formula, n is an integer of _{1 to 3} , at least one of R ₁ , R ₂ , and R ₃ is a perfluoroalkyl group having 3 or more carbon atoms, and R is a hydrocarbon group.) A magnetic recording medium having a perfluoroalkylamine carboxylate.