JPH0461026A - Magnetic recording mdeium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium excellent in traveling property, durability and corrosion resistance by forming a magnetic layer on a substrate and providing a protective layer containing a rust preventive and fluourinated polyether polymers having a specified molecular structure on this magnetic layer. CONSTITUTION:By applying a rust preventive and fluorinated polyether polymers having the molecular structure expressed by the formula I as the unit on a magnetic layer at one time, a uniform protective layer containing the rust preventive and the polymers is formed on the magnetic layer. In the formula I,(n) is an integer 1-18 and (m) is an integer satisfying m<=n. The obtd. magnetic recording medium has improved traveling property, durability and corrosion resistance, and therefore, a video tape comprising this medium has low coefft. of friction, small jitter, and good durability and corrosion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium that has excellent running properties, durability, and corrosion resistance.

[Prior Art] Generally, 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 or the like. ferromagnetic metal thin film type magnetic recording media formed by vacuum evaporation, etc. and metal magnetic powder bonded together by a binder component are particularly susceptible to abrasion of the magnetic layer due to violent sliding contact with magnetic heads etc. during recording and reproduction. Although these magnetic recording media have excellent high-density recording properties, they have a large coefficient of friction with the magnetic head, making them susceptible to wear and damage, and they also gradually undergo oxidation in the air, deteriorating their magnetic properties such as maximum magnetic flux density. There are some drawbacks such as:

For this reason, a protective layer made of a fluorine compound such as perfluoroalkyl polyether or an aliphatic compound such as fatty acid or fatty acid ester is provided on the magnetic layer to sufficiently reduce the coefficient of friction and improve running performance, durability, and corrosion resistance. Improvements have been made (Japanese Patent Application Laid-open No. 60-109028, JP-A No. 61-11926). Corrosion resistance cannot be sufficiently improved just by using a rust preventive agent, so it is necessary to use a rust preventive agent at the same time. However, since the solvents that dissolve the two are different, and multiple coats must be applied, it is difficult to obtain a uniform protective layer. cannot be formed. Furthermore, aliphatic compounds cannot sufficiently reduce the coefficient of friction, and conventional fluorine-based compounds and aliphatic compounds have not yet been able to sufficiently improve running performance, durability, and corrosion resistance.

[Means for Solving the Problems] This invention was made as a result of various studies in view of the current situation. An integer, m is an integer satisfying m≦n.) By simultaneously coating a fluorinated polyether polymer with a unit of m≦n on a magnetic layer and a rust preventive agent, a uniform protective layer containing these can be made magnetic. It is formed on a layer to sufficiently reduce the coefficient of friction and sufficiently improve running performance, durability, and corrosion resistance.

The fluorinated polyether polymer used in the present invention has an excellent lubrication function and clear water oil repellency in the fluorinated polyether polymer portion, and is soluble in organic solvents such as ketones and alcohols. The rust preventive agent is also mixed with the rust preventive agent. Therefore, a mixed solution in which these fluorinated polyether polymers and the rust preventive agent are mixed and dissolved is coated or sprayed on the magnetic layer, or the magnetic layer is placed in the above solution. It can be uniformly deposited on the magnetic layer by a method such as dipping, and the uniform protective layer made of the fluorinated polyether polymer and rust preventive agent sufficiently improves runnability, durability, and corrosion resistance. Ru.

In particular, the fluorinated polynythyl polymer has a -COOR group (wherein R is a hydrogen atom, an alkali metal, or a saturated or unsaturated hydrocarbon group having 1 to 1 carbon atoms) at at least one end. If it has, at least one end of the backbone has one C
Since the OOR group has excellent affinity with the hydrophilic magnetic layer, the -COOR group is oriented and strongly adsorbed to the magnetic layer surface, and does not dissipate from the magnetic layer surface even after long-term use, maintaining magnetic properties. Separation from the layer surface is sufficiently suppressed. Therefore, this type of fluorinated polyether polymer having a 1000R group at at least one end is firmly adhered to the surface of the magnetic layer to form a protective layer with excellent lubricity, and is suitable for magnetic heads. The protective layer does not peel off due to sliding contact with the rubber, the friction coefficient is sufficiently reduced, running properties are improved, and jitter characteristics are also sufficiently improved. Furthermore, the durability is sufficiently improved, and the corrosion resistance is also sufficiently improved by the rust preventive agent used in combination.

Such a fluorinated polyether polymer is preferably one in which n in the molecular skeleton represented by the above general formula is an integer of 1 to 18, and m is an integer such that m≦n, - R in the COOR group is preferably a hydrogen atom, an alkali metal, or a saturated or unsaturated hydrocarbon group having 1 to 18 carbon atoms.

As such a fluorinated polyether polymer, for example, those represented by 2 are preferably used.

In addition, examples of rust preventives used in combination include benzotriazole, tolyltriazole, benzimidazole, morpholine, m-cabutobenzotriazole, melyltriazole, cyclohexylammonium carbonate, diisopropylammonium nitrite, N-
Any of those commonly used as rust inhibitors, such as nitrosodimethylamine, diisopropylamine, octadecylamine, methylpropylamine, and stearylamine, are preferably used, and these are all compatible with the above-mentioned fluorinated polyether polymer. It is soluble in organic solvents such as ketones and alcohols that dissolve , and has good compatibility with the above-mentioned fluorinated polyether polymers. Therefore, when these rust inhibitors are used in combination with the above-mentioned fluorinated polyether polymers,
The fluorinated polyether polymer sufficiently improves runnability and durability, and at the same time, the rust inhibitor sufficiently improves corrosion resistance.

When such a rust inhibitor is used in combination with the fluorinated polyether polymer, the weight ratio of the rust inhibitor to the fluorinated polyether polymer is 1:10 to 1:1.
It is preferable to keep it within the range of .

The rust inhibitor and the fluorinated polyether polymer described above are dissolved in a suitable solvent such as ketone or alcohol, and the magnetic layer is immersed in the solution obtained by dissolution, or the above solution is soaked in a magnetic layer. It is deposited on the magnetic layer by coating or spraying on the surface of the layer. The amount of adhesion is 0.1~
It is preferable to deposit within the range of 5.0■/rl,
If it is too small, the desired effect will not be obtained, and if it is too large, it will cause a decrease in output or dropout.

The magnetic layer formed on the substrate is made of γ-FezO:I powder,
Fe50. Powder, Co-containing 1-FezO:I powder, Co
Contains Fe50. Powder, Cr Oz powder, Fe powder, Co
Magnetic powder such as powder, Fe-Ni powder, barium ferrite, etc. is coated on a substrate together with a binder resin and an organic solvent and dried, or Co, Ni, Fe, Co, etc.
- Formed by a method such as depositing a ferromagnetic material such as Ni, Co-Cr, Co-P, Co-Ni -P on a substrate by means such as vacuum evaporation, ion blasting, sputtering, plating, etc. .

Further, the magnetic recording medium includes various types of structures that come into sliding contact with a magnetic head, such as a magnetic tape having a synthetic resin film such as a polyester film as a base, a magnetic disk or a magnetic drum having a disk or drum as a base.

〔Example] Next, embodiments of the invention will be described.

Example 1 A 10 μm thick polyester film was filled in a vacuum evaporation apparatus, and a cobalt-nickel alloy was heated once under a vacuum of 5 x 10-') to form a 0.15 μm thick cobalt film on the polyester film. A ferromagnetic metal thin film layer made of a nickel alloy was formed. Next, this was immersed in a mixed solution of a 061% by weight isobrobyl alcohol solution of a polyether copolymer represented by the chemical formula below and a 0.1% by weight isopropyl alcohol solution of benzotriazole, and dried. After forming the protective layer, slits were made into 8 pieces to make a videotape.

Example 2 α-Fe @ powder 80 parts by weight VAGH
(manufactured by U, C, C, vinyl chloride-vinyl acetate-vinyl alcohol copolymer) N-2309 (Japan Polyurethane 4, manufactured by Kogyo Co., Ltd., polyurethane resin) Coronate L (Japan Polyurethane 2, manufactured by Kogyo Co., Ltd., Trifunctional low molecular weight isocyanate compound) Cyclohexanone 65 Toluene
65〃This composition was mixed and dispersed in a ball mill for 100 hours to prepare a magnetic paint, and 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 layer. Formed. Next, in the same manner as in Example 1, this was immersed in a mixed solution of a 0.1 weight percent isopropyl alcohol solution and a 0.1 weight percent isopropyl alcohol solution of benzotriazole, and dried to form a protective layer. After forming, it was slit into 8-width strips to make a videotape.

Comparative Example 1 In the formation of the protective layer in Example 1, 0.1 of CF ff CF z CF HCHz O+COOCH3
Omitting the wt % isopropyl alcohol solution, immersing benzotriazole in a 0.1 wt % isopropyl alcohol solution and drying to form the first protective layer, and then adding Phonoblin ZDEAL (manufactured by Enimont, perfluoroalkyl polyether). A videotape was prepared in the same manner as in Example 1, except that the second protective layer was laminated by immersing it in a 0.1 wt % Freon solution of ) and drying.

Comparative Example 2 In forming the protective layer in Example 2, CF3 dried CF
z CF HCHz OtoC00CH.

omitting the 0.1 wt% isopropyl alcohol solution of benzotriazole, and drying to form the first protective layer. A videotape was made in the same manner as in Example 2, except that the second protective layer was laminated by immersing it in a 0.1% by weight Freon solution (polyether) and drying it.

The friction coefficient and jitter characteristics of the video tapes obtained in each Example and each Comparative Example were measured, and the durability and corrosion resistance were tested. The coefficient of friction is the surface roughness of 0.2S,
Outer diameter 4! ! The obtained videotape was wound around a cylindrical bottle of 150 mm at a winding angle of 150 @, a load of 21 g was applied, and the feed rate was 1.
．． The friction coefficient of the 100th bath was determined by feeding at a rate of 4 cm/see and repeatedly measuring the same spot. In addition, the jitter characteristics were determined by loading the obtained videotape into a video deck and recording and playing back the video signal.
This was done by measuring the gap in the Hz horizontal synchronization signal.

Furthermore, the durability test was performed by running and playing the obtained videotape at a head load of 5 g and a running speed of 0.048 m/sec under conditions of 25 ° C and 260% RH until the output decreased by 3 dB from the initial output. This was done by measuring the number of times the vehicle was run. Further, the corrosion resistance test was carried out by leaving the obtained videotape under the conditions of 60° C. and 190% RH for 168 hours and measuring the maximum magnetic flux density. Note that the measured values are expressed as values compared with the maximum magnetic flux density of the videotape before being left as 100%.

Table 1 below shows the results.

Table 1 [Effects of the Invention] As is clear from the above table, the video tapes obtained by the present invention (Examples 1 and 2) are both comparable to conventional video tapes (Comparative Examples 1 and 2). death,! 11 coefficient and small jitter, good durability and corrosion resistance,
This shows that the magnetic recording medium obtained by the present invention has further improved running properties, durability, and corrosion resistance.

Claims (1)

[Claims] 1. A magnetic layer is formed on a substrate, and on this magnetic layer, a molecular skeleton has ▲a mathematical formula, a chemical formula, a table, etc.▼ (however, n is an integer from 1 to 18, m is A magnetic recording medium 2 characterized in that a protective layer containing a fluorinated polyether polymer having units of m≦n and a rust preventive agent is provided, the fluorinated polyether polymer is is a fluorinated polyether polymer having a -COOR group at at least one end (wherein R is a hydrogen atom, an alkali metal, or a saturated or unsaturated hydrocarbon group having 1 to 18 carbon atoms). Magnetic recording medium according to claim 1