JPS63171422A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide sufficient lubricity and water- and oil repellency to a titled medium and to improve the corrosion resistance, durability and runnability thereof by incorporating specific perfluoroether having >=1 nitrogenous heterocycles at the molecular terminal into the surface of the recording medium. CONSTITUTION:The magnetic layer is formed on the surface of the recording medium by using the perfluoroether which is expressed by the formula and into the molecular terminal of which >=1 kinds of the nitrogenous heterocycles selected from triazoles, imidazoles, carbazoles and indoles are incorporated. Said nitrogenous heterocycles are securely bonded to the magnetic layers, are not detached from the surface of the magnetic layer in long-term use and have the sufficient lubricating function and water- and oil repellency. Said cycles have a small coefft. of friction and jitter characteristic and contribute to improvement in the corrosion resistance, runnability and durability.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording medium using a metal magnetic material as a recording element, and more specifically to the above-mentioned magnetic recording medium that has excellent running properties, durability, and corrosion resistance. Regarding.

[Conventional technology]

In general, magnetic recording media are made by binding magnetic powder together with a binder component onto a base film, or by depositing ferromagnetic metals or their alloys on a base film by vacuum deposition, etc. The magnetic layer is likely to be worn out due to violent sliding contact with the magnetic head and the like. In particular, ferromagnetic metal thin film type magnetic recording media and metal magnetic powder formed by vacuum evaporation etc. are bonded together with a binder component (
Although the magnetic recording media produced by this technology have excellent high-density recording characteristics,
It has a large coefficient of friction with the magnetic head, making it susceptible to wear and damage, and it also suffers from gradual oxidation in the air, degrading magnetic properties such as maximum magnetic flux density.

In addition, in general, magnetic recording media such as magnetic tapes use substrates with good smoothness, and the surface of the magnetic layer is also smooth, so the magnetic tape easily adheres to guide rolls etc. when running. In particular, in the case of ferromagnetic metal thin film magnetic recording media, which are made by depositing metals or alloys on a substrate by vacuum deposition, the smoothness of the substrate may be higher than that of the ferromagnetic metal thin film. Since the smoothness of the layer directly reflects the electromagnetic conversion characteristics, we use a substrate with very good smoothness.
The base has a large coefficient of friction and easily adheres to guide rolls etc. during running. As a result, the magnetic tape becomes stuck to the guide roll, causing stretching and deformation of the tape.
Further, there are disadvantages such as skip slips and deterioration of jitter characteristics.

For this reason, a protective layer made of a fluorine-based lubricant such as perfluoropolyether is provided on the magnetic layer to improve runnability and durability (Japanese Patent Application Laid-open No. 109028/1983), or a protective layer made of a fluorine-based lubricant such as benzotriazole is used to improve running properties and durability. Corrosion resistance is improved by providing a back coat layer consisting of a
No. 2621) is being carried out.

[Problem that the invention seeks to solve]

However, this kind of fluorine-based lubricant that has been used in the past has a particularly weak interaction with the surface of the magnetic layer where the recording element is a metal magnetic material, and is easily separated from the surface of the magnetic layer by sliding contact with the magnetic head. Therefore, improvements in runnability and durability have not yet been sufficient, and although corrosion resistance has been improved with a back coat layer made of a rust preventive agent such as benzotriazole, it has not yet been fully satisfactory. do not have.

[Means to solve the problem]

This invention was made as a result of various studies in view of the current situation, and includes at least one type selected from the group consisting of the formula %, W, and Z.
is -F, -H, -OH, -CH3, -0303H.

-C0OH, where a, b, c, and d are integers from O to 150, n is an integer from 1 to 50, and R is H or an alkyl group. ] A metal magnetic material containing at least one nitrogen-containing heterocycle selected from triazoles, imidazoles, carbazoles, and indoles at the molecular end of perfluoropolyether represented by By including the magnetic layer on the front or back side of a magnetic recording medium, or on both the front and back sides, the friction against the magnetic head or guide pin can be lowered, and the rust-preventing effect of the nitrogen-containing heterocycle can be fully exhibited, making it easier to run. It has sufficiently improved hardness, durability, and corrosion resistance. Furthermore, formula % formula %) [However, n is an integer from 1 to 40, and l is an integer from 1 to 50. ] By using the fluorine-based solid lubricant represented by the above in combination with at least one perfluoropolyether having a nitrogen-containing heterocycle at the end of the molecule, running properties, durability, and corrosion resistance can be further improved. It is something that

The perfluoropolyether having a nitrogen-containing heterocycle used in the present invention has at least one nitrogen-containing heterocycle selected from triazoles, imidazoles, carbazoles, and indoles at the end of the molecule. , these nitrogen-containing heterocycles have excellent affinity with a magnetic layer whose recording element is a hydrophilic metallic magnetic material, so when a protective layer is formed on the magnetic layer using them, these nitrogen-containing heterocycles The rings are oriented and firmly adsorbed to the surface of the magnetic layer, and do not dissipate from the surface of the magnetic layer even after long-term use, and are sufficiently inhibited from detaching from the surface of the magnetic layer. In addition, since the perfluoropolyether part is oriented on the surface opposite to the magnetic layer side to form a protective layer, the excellent lubrication and water and oil repellent functions of this perfluoropolyether part are sufficient on the surface of the protective layer. It is demonstrated. Furthermore, since the aforementioned nitrogen-containing heterocycles bonded to at least one end of the perfluoropolyether molecule have an excellent rust-preventing effect, these nitrogen-containing heterocycle moieties can sufficiently exhibit the rust-preventing effect. . Therefore, this type of perfluoropolyether having a nitrogen-containing heterocycle is firmly adhered to the surface of a magnetic layer using a metal magnetic material as a recording element, forming a protective layer with excellent lubricity and corrosion resistance, and forming a protective layer for magnetic heads. The protective layer does not peel off due to sliding contact with the rubber, and running properties and durability are sufficiently improved, and corrosion resistance and jitter characteristics are also sufficiently improved.

In addition, a bank coat layer may be formed directly on the back side of a substrate on which a magnetic layer is formed using this type of perfluoropolyether, or this type of bank coat layer may be further formed on the back coat layer already formed on the back side of the substrate. Forming the back coat layer using perfluoropolyether prevents the back coat layer from peeling off, and further prevents blocking, sufficiently improving runnability and durability, as well as corrosion resistance and jitter characteristics. be done.

Furthermore, on the magnetic layer formed on the surface of the substrate, for example,
When a plasma polymerized protective film layer is formed by plasma polymerization of a monomer gas of an organic polymer compound, and a protective layer is further formed using this type of perfluoropolyether on this plasma polymerized protective film layer, the plasma polymerized film and the perfluoropolyether are formed. Adhesion to fluoropolyether is improved, abrasion resistance is improved, runnability and durability are sufficiently improved, and corrosion resistance and jitter characteristics are also sufficiently improved.

At least one such nitrogen-containing heterocycle is present at the end of the molecule.
As the perfluoropolyether having the above, for example, those represented by the formula are preferable, singly or in combination.
Used in combination with more than one species. s, t in these formulas
is preferably an integer from 5 to 100, and U is an integer from 1 to 20. When S and t are larger than 100, stiffness occurs, and when U is larger than 20, the coefficient of friction becomes large.

In addition, the fluorine-based solid lubricant represented by the above formula is solid and has excellent lubricating and water- and oil-repellent functions, and is compatible with the perfluoropolyether having a nitrogen-containing heterocycle at the end of the molecule. Good. Therefore, when this fluorine-based solid lubricant is used in combination with the above-mentioned perfluoropolyether having a nitrogen-containing heterocycle at the end of the molecule, the solid-liquid two-phase lubricating effect is fully exhibited and the coefficient of friction is sufficiently reduced. , running properties, durability and corrosion resistance are further improved.

Preferred examples of such fluorine-based solid lubricants include those represented by the above formula, and four or more perfluoropolyethers having a nitrogen-containing heterocycle at the end of the molecule. used in conjunction with. In these formulas, n is preferably an integer from 1 to 40, and l is an integer from 1 to 50. When n is larger than 40, synthesis is difficult, and when l is larger than 50, the coefficient of friction becomes high.

When such a fluorine-based solid lubricant is used in combination with a perfluoropolyether having a nitrogen-containing heterocycle at the end of the molecule, the proportion of both should be adjusted to the weight ratio of the fluorine-based solid lubricant to perfluoropolyether. 0.01 to 1
It is preferable to set the ratio within the range of 1 to 0.01.

Perfluoropolyether having a nitrogen-containing heterocycle at the end of the molecule is dissolved in a suitable solvent such as Freon, and in the solution obtained by dissolution, the magnetic layer formed on the substrate, the back surface of the substrate, Either the back coat layer formed on the back surface of the substrate and the protective layer such as the plasma polymerized protective film layer further formed on the magnetic layer on the substrate are immersed, or the solution is applied to the magnetic layer, the back surface of the substrate, or the back coat layer formed on the magnetic layer on the substrate. coat layer,
It is deposited on the magnetic layer, the back surface of the substrate, the back coat layer, the plasma polymerized protective layer, and other protective layers by coating or spraying on the surface of the protective layer, such as the plasma polymerized protective layer. The coating thickness when applied is 10 to 2 in dry thickness.
It is preferable that the thickness be within the range of 0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000. Furthermore, if a perfluoropolyether having a nitrogen-containing heterocycle at the end of the molecule and a fluorine-based solid lubricant are used together, both are dissolved in a suitable solvent such as Freon, and the magnetic layer and back side of the substrate are coated in the same manner as above. , a backcoat layer, a plasma polymerized overcoat layer, and other protective layers. When applied, the total dry thickness of both coatings is preferably within the range of 10 to 200. If it is thinner than this, the desired effect will not be obtained, and if it is too thick, it may cause a decrease in output or dropout. It causes

The magnetic layer formed on the substrate is made of Fe powder and C.

A magnetic paint is prepared by mixing and dispersing metal magnetic powder such as powder, Fe-Ni powder, etc. with a binder resin and an organic solvent, and this magnetic paint is applied onto a substrate and dried. .

It is formed by depositing a ferromagnetic material such as -Ni, Co-Cr5Co-P% Go-Ni -P on a substrate by vacuum evaporation, ion blasting, sputtering, coating, or the like.

In addition, for the back coat layer formed on the back surface of the substrate, a paint for the back coat layer is prepared by mixing and dispersing fillers such as red iron, barium sulfate, calcium carbonate, and carbon black together with a binder resin and an organic solvent. This back coat layer coating material is applied to the back surface of a substrate on which a magnetic layer is formed, and then dried.

Further, the plasma polymerized protective film layer formed on the magnetic layer by plasma polymerization or the like is formed by plasma polymerizing a 7-mer gas of an organic compound such as ethylene, hexamethyldisilazane, or c2F.

Magnetic recording media include various types of structures that come into sliding contact with a magnetic head, such as magnetic tapes having synthetic resin films such as polyester films as bases, magnetic disks and magnetic drums having disks or drums as bases.

〔Example〕

Next, embodiments of the invention will be described.

Examples 1 to 4 A 12 μm thick polyester film was loaded into a vacuum deposition apparatus, and cobalt was heated and evaporated under a vacuum of 5×10 −5 Torr to form a 0.2 μm thick cobalt ferromagnetic material on the polyester film. A metal thin film layer was formed.

Next, the following back coat coating material was applied to the back surface of the polyester film having a ferromagnetic metal thin film layer formed on the surface thereof and dried to form a back coat layer having a thickness of 160 μm.

Paint carbon blank for back coat layer 270 parts by weight cx-F
e203 powder 30 Polyurethane resin
70〃Nitrified cotton
100〃Trifunctional low molecular weight isocyanate-30〃 compound cyclohexanone 750〃Toluene
750 Next, apply a 0.5% by weight Freon solution of perfluoropolyether shown in Table 1 below on the ferromagnetic metal thin film layer and the back coat layer so that the dry thickness of both is 60%. After drying, a protective layer and a back coat layer made of perfluoropolyether were formed on the magnetic layer and the previously formed lower bank coat layer, and the tape was cut to a predetermined width to produce a magnetic tape.

Example 5 In forming the protective layer and back coat layer in Example 1, 0.5% by weight of the solid lubricant CeFt7COOH was added to the 0.5% by weight Freon solution of perfluoropolyether.
A wt% Freon solution is added and mixed, and this mixed solution is applied onto the magnetic layer and the lower back coat layer to a dry thickness of 60 mm, and dried to form a protective layer made of perfluoropolyether. A magnetic tape was produced in the same manner as in Example 1, except that a back coat layer was formed on the magnetic layer and the previously formed lower back coat layer.

Example 6 Fe magnetic powder 80 parts by weight VAGH
(Manufactured by 11, c, company c, vinyl chloride 16-vinyl acetate-vinyl alcohol copolymer) Takenate L-1007 (take 1) 4 Manufactured by Yakuhin Kogyo Co., Ltd., urethane prepolymer) Methyl isobutyl ketone 61 Toluene
61〃This composition was mixed and dispersed in a ball mill for 72 hours to prepare a magnetic paint, and this magnetic paint was coated on a polyester film with a dry thickness of 6 μm.
A magnetic layer was formed by coating and drying to a thickness of μm.

Next, a Basok coat layer was formed on the back side of the polyester film on which the magnetic layer was formed in the same manner as in Example 1,
Furthermore, a protective layer and an upper bank coat layer each made of perfluoropolyether having a dry thickness of 60 μm were formed on the magnetic layer and back coat layer in the same manner as in Example 1, and then cut to a predetermined width. and created magnetic tape.

Example 7 A ferromagnetic metal thin film layer was formed in the same manner as in Example 1, and then the polyester film on which the ferromagnetic metal thin film layer was formed was loaded into a processing tank, and a monomer gas of hexamethyldisilazane was introduced from the gas inlet pipe. was introduced at a flow rate of 10105e, the gas pressure was 0.03 ) -l, and the high frequency power density I W/a
Plasma polymerization was performed at nt for 20 seconds to form a plasma polymerized protective film layer with a thickness of 100 mm. Thereafter, a back coat layer was formed in the same manner as in Example 1, and a protective layer and an upper layer made of perfluoropolyether having a dry thickness of 60 mm were further formed on the plasma polymerized protective film layer and the back coat layer. A back coat layer was formed, and the magnetic tape was cut to a predetermined width.

Example 8 A magnetic tape was produced in the same manner as in Example 1, except that the formation of the upper back coat layer made of perfluoropolyether on the back coat layer was omitted.

Example 9 A magnetic tape was produced in the same manner as in Example 5, except that the formation of the upper back coat layer consisting of perfluoropolyether and fluorine-based solid lubricant on the back coat layer was omitted. .

Example 10 A magnetic tape was produced in the same manner as in Example 6, except that the formation of the upper back coat layer made of perfluoropolyether on the back coat layer was omitted.

Example 11 A magnetic tape was produced in the same manner as in Example 7, except that the formation of the upper back coat layer made of perfluoropolyether on the back coat layer was omitted.

Example 12 A magnetic tape was produced in the same manner as in Example 1, except that the formation of a protective layer made of perfluoropolyether on the magnetic layer was omitted.

Example 13 A magnetic tape was produced in the same manner as in Example 5, except that the formation of a protective layer made of perfluoropolyether and a fluorine-based solid lubricant on the magnetic layer was omitted.

Example 14 A magnetic tape was produced in the same manner as in Example 6, except that the formation of a protective layer made of perfluoropolyether on the magnetic layer was omitted.

Example 15 A magnetic tape was produced in the same manner as in Example 7, except that the formation of a protective layer made of perfluoropolyether on the plasma polymerized protective film layer was omitted.

Comparative Examples 1 to 2 In the formation of the protective layer and upper bank coat layer in Example 1, perfluoropolyethers shown in Table 1 below were used in place of the 0.5% by weight Freon solution of perfluoropolyethers. A magnetic tape was produced in the same manner as in Example 1 except that a 0.5 wt % Freon solution was used to form a protective layer with a thickness of 60 mm and an upper back coat layer.

Comparative Example 3 In the formation of the protective layer and the upper back coat layer in Example 6, 0.5 wt % Freon solution of perfluoropolyether was replaced with 0.5 wt % Freon solution of perfluoropolyether shown in Table 1 below. A magnetic tape was produced in the same manner as in Example 6, except that a 5% by weight Freon solution was used to form a protective layer with a thickness of 60 mm and an upper back coat layer.

Comparative Example 4 In the formation of the protective layer and upper bank coat layer in Example 7, 0.5% by weight Freon solution of perfluoropolyether was replaced with 0.5% Freon solution of perfluoropolyether shown in Table 1 below. A magnetic tape was produced in the same manner as in Example 7 except that a 5% by weight Freon solution was used to form a protective layer and an upper back coat layer with a thickness of 60 mm.

Comparative Example 5 A magnetic tape was produced in the same manner as in Comparative Example 1, except that the formation of the upper back coat layer made of perfluoropolyether on the back coat layer was omitted.

Comparative Example 6 A magnetic tape was produced in the same manner as in Comparative Example 3, except that the formation of the upper back coat layer made of perfluoropolyether on the back coat layer was omitted.

Comparative Example 7 A magnetic tape was produced in the same manner as in Comparative Example 4, except that the formation of the upper back coat layer made of perfluoropolyether on the back coat layer was omitted.

Comparative Example 8 A magnetic tape was produced in the same manner as in Comparative Example 1, except that the formation of a protective layer made of perfluoropolyether on the magnetic layer was omitted.

Comparative Example 9 A magnetic tape was produced in the same manner as in Comparative Example 3, except that the formation of a protective layer made of perfluoropolyether on the magnetic layer was omitted.

Comparative Example 10 A magnetic tape was produced in the same manner as in Comparative Example 4, except that the formation of a protective layer made of perfluoropolyether on the magnetic layer was omitted.

Regarding the magnetic tapes obtained in each example and comparative example,
The coefficient of friction was measured and the jitter properties, corrosion resistance and durability were tested. The friction coefficient was determined by measuring the initial friction coefficient between the magnetic layer side and the bank coat layer side. In addition, in the jitter characteristic test, the obtained magnetic tape was loaded into a video deck, a video signal was recorded and played back, and the playback signal was measured at 15.75 KHz.
Read the horizontal synchronization signal interval of
Measurements were made separately after 300 days and after 300 days. Furthermore, a corrosion resistance test was conducted on the obtained magnetic tape at 60°C and 90% RH.
The test was carried out by leaving the sample under the following conditions for 7 days and measuring the maximum magnetic flux density after leaving it. Note that the measured values are expressed as values compared with the maximum magnetic flux density of the magnetic tape before being left as 100%.

In addition, the durability test was carried out by loading the obtained magnetic tape into a video deck, recording and reproducing video signals under conditions of 20°C and 150% RH, and measuring the time until the output decreased by 3 dB, that is, the still life. went.

Table 2 below shows the results.

〔Effect of the invention〕

As is clear from Table 2 above, the magnetic tapes obtained according to the present invention (Examples 1 to 15) have better friction coefficients and jitter characteristics than conventional magnetic tapes (Comparative Examples 1 to 10). It is small in size, has a long still life, and has good corrosion resistance, which shows that the magnetic recording medium obtained by the present invention has further improved running properties, durability, and corrosion resistance.

Claims (1)

[Scope of Claims] 1. A magnetic recording medium having a magnetic layer having a magnetic metal material as a recording element on the surface of the substrate has a permeable material having one or more nitrogen-containing heterocycles at least at the end of the molecule on the front or back surface or both the front and back surfaces. A magnetic recording medium characterized by containing fluoropolyether. 2. The magnetic recording medium according to claim 1, wherein the nitrogen-containing heterocycle is at least one selected from triazoles, imidazoles, carbazoles, and indoles. 3. Perfluoropolyether has the formula ▲ Numerical formula, chemical formula, table, etc. ▼ [However, X and Y are -CH_2-, -CF_2-, -CO
O-, -COO-[CH_2CH_2O]--[CH_2CH
_2O] - At least one selected from the group consisting of W and Z, ▲ has a mathematical formula, chemical formula, table, etc. ▼ -F, -H, -OH, -CH_3, -OSO_3H, -
at least one selected from the group consisting of COOH, where a, b, c, and d are integers from 0 to 150;
n is an integer from 1 to 50, and R is H or an alkyl group. ] The magnetic recording medium according to claim 1, which is a perfluoropolyether represented by: 4. Further, on the front or back surface or both the front and back surfaces of the magnetic recording medium, the formula C_nF_2_n_+_1COOH C_nF_2_n_+1(C_2H_4O)lCOOH
C_nF_2_n_+_1(CH_2)lOHC_nF
_2_n_+_1(CH_2)lCOOHC_nF_2
_n_+_1(CH_2)lCH_2OOCH=CH_
2C_nF_2_n_+_1(CH_2)lCH_2O
OCC(CH_3)=CH_2C_nF_2_n_+_
1SO_2N(C_3H_7)C_2H_4OPO(O
H)_2 [However, n is an integer from 1 to 40, and l is an integer from 1 to 50. ] The magnetic recording medium according to any one of claims 1 to 3, containing at least one kind of fluorine-based solid lubricant selected from the fluorine-based solid lubricants represented by the following. 5. The blending ratio of the perfluoropolyether having a nitrogen-containing heterocycle and the fluorinated solid lubricant is 1:0 in terms of weight ratio of perfluoropolyether to fluorinated solid lubricant.
．． 5. The magnetic recording medium according to claim 4, wherein the ratio is within a range of 0.01 to 0.01:1. 6. Claims 1 to 6, wherein the magnetic recording medium is a magnetic recording medium in which a ferromagnetic metal thin film layer is provided on the surface of the substrate, and a plasma polymerized protective film layer made of an organic polymer compound is further provided thereon. The magnetic recording medium according to item 5.