JP2719016B2 - Magnetic recording media - Google Patents

Description

The present invention relates to a magnetic recording medium, and more particularly, to a magnetic recording medium having excellent durability.

[Problems to be solved by conventional technology and invention]

A magnetic recording medium slides violently with a magnetic head or a pad at the time of recording / reproducing and the magnetic layer is easily worn. Therefore, a magnetic recording medium which has little wear of the magnetic layer and has excellent durability is desired.

Therefore, as a measure to improve the wear resistance of the magnetic layer,
An internal addition method in which various lubricants are mixed into the magnetic layer, a top coating method in which a lubricating layer is formed on the surface of the magnetic layer, and the like are performed.

Conventionally used lubricants include higher fatty acids and their esters, fatty acid amides, liquid paraffin,
There are silicone oils and the like. However, at present, these lubricants are hardly satisfactory in terms of performance.

[Means for solving the problem]

The present inventors have made intensive studies to obtain a magnetic recording medium having good lubricity and significantly improved durability, and have reached the present invention.

That is, the present invention provides a magnetic recording medium having a magnetic layer on a nonmagnetic support, wherein the magnetic layer holds a compound represented by the following general formula (1). To provide.

(Wherein, R ₁ is a hydrocarbon group having 3 to 23 carbon atoms, and R ₂ is a hydrocarbon group having 1 carbon atom.
To 20 hydrocarbon groups, R ₃ and R ₄ are hydrogen atoms or carbon atoms of 1 to 8
Represents a hydrocarbon group or a phenyl group. ) In (the compound represented by 1) (hereinafter Compound (1) wherein the general formula according to the present invention referred to as), although R ₁ as described above is a hydrocarbon group having 3 to 23 carbon atoms, R ₁ Has preferably 11 to 21 carbon atoms, and more preferably 13 to 17 carbon atoms. Further, this R ₁ may have a linear or branched chain,
Further, it may be saturated or have an unsaturated bond.

R ₂ is a hydrocarbon group having 1 to 20 carbon atoms, and may be linear or branched.

R ₃ and R ₄ are a hydrogen atom, a hydrocarbon group having 1 to 8 carbon atoms or a phenyl group, and particularly preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms.

Compound (1) is prepared by combining the fatty acid represented by the following formula (2) R ₁ -COOH (2) with the following formula (3) And obtained by a usual esterification reaction with an alcohol represented by

The alcohol represented by the general formula (3) is represented by the following formula (4) And a ketone or aldehyde represented by the following formula (5) Can be easily obtained by reacting with a trimethylol compound represented by the following method according to a known method (for example, Org. Synth., III, 502 (1955)).

The trimethylol compound represented by the general formula (5) includes an aldehyde represented by the following formula (6) R ₂ —CH ₂ —CHO (6) and a formaldehyde represented by the following formula (7) HCHO (7) And the presence of a base,
It can be obtained by reacting according to the methods disclosed in JP-A-62-8419, JP-A-61-148134 and JP-A-63-11333.

Representative examples of the aldehyde represented by the general formula (6) include propionaldehyde and butyraldehyde.
As described above, octyl aldehyde, dodecyl aldehyde, stearyl aldehyde, etc. having a longer chain can also be used.

The addition amount of the compound (1) to the magnetic recording medium in the invention is preferably 0.05 to 15 parts by weight per 100 parts by weight of the magnetic material. If necessary, other general-purpose lubricants such as esters such as butyl stearate, fatty acids such as oleic acid, and hydrocarbons such as squalane may be used in combination.

The compound (1) in the present invention may be previously mixed into a coating material or may be mixed with isopropanol,
By applying and drying a solution of a general-purpose solvent such as hexane, the coating film can be impregnated and used.

Further, a medium formed by forming a magnetic layer on a non-magnetic support by sputtering or vapor deposition can be applied and used in the same manner.

Examples of the magnetic powder used in the magnetic recording medium of the present invention include metal oxides such as fine needle-like γ-Fe ₂ O ₃ , Fe ₃ O ₄ and CrO ₂ , and Co-coated γ-Fe ₂ O ₃ , Co-doped γ-Fe ₂ O ₃ subjected to processing such as γ-Fe ₂ O ₃ , metallic iron powder, barium ferrite in the form of platelets and a part of its Fe atoms are Ti, Co, Zn,
Magnetic powder substituted with one or more of V, Nb, etc., Co, Fe
And ultrafine powder of a metal or alloy such as -Co, Fe-Ni. Of these, metallic iron powder has particularly poor chemical stability, and nickel, cobalt, titanium, silicon, aluminum, etc. may be added in small amounts in the form of metal atoms, salts and oxides or surface-treated for this improvement. However, these can also be used. In order to stabilize the metallic iron powder, a thin oxide film may be formed on the surface in a weak oxidizing atmosphere. However, a metal powder treated in this manner can be used. Further, two or more kinds of the above-mentioned magnetic powders may be mixed and used.

Examples of the binder used in the present invention to form a magnetic layer by dispersing magnetic powder include polyurethane, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer,
Polyacrylonitrile, nitrile rubber, epoxy resin,
Examples include alkyd resin, polyamide, polyacrylate, polymethacrylate, polyvinyl acetate, polyvinyl butyral, vinylidene chloride, nitrified cotton, maleic acid-modified vinyl chloride-vinyl acetate copolymer, and ethyl cellulose. These may be used alone or in combination of two or more. Further, a plasticizer or a curing agent may be added to adjust the hardness of the resin.

The magnetic layer of the magnetic recording medium of the present invention, in addition to the above components,
Additives usually used in this field, such as abrasives and antistatic agents, can be added.

Examples of the nonmagnetic support used in producing the magnetic recording medium of the present invention include: polyesters such as polyethylene terephthalate; polyolefins such as polyethylene and polypropylene; cellulose derivatives such as cellulose triacetate and cellulose diacetate; polycarbonate; Plastics such as vinyl chloride; polyimide; aromatic polyamide; metals such as Al and Cu; paper; The form may be any of film, tape, sheet, disk, card, drum and the like. The surface of the support may be treated with corona discharge, radiation, ultraviolet light, or the like, or may be precoated with an appropriate resin.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited to these Examples.

Examples 1-4 Metallic iron powder 100 parts by weight Vinyl chloride-vinyl acetate copolymer ^{* 1} 11 {polyurethane resin ^{* 2} 11 ^} carbon black (antistatic agent) 2 {Cr ₂ O ₃ (polishing agent) 10} toluene 71メ チ ル Methyl ethyl ketone 71 シ ク ロ Cyclohexanone 107 〃 Note) * 1: Product name: VAGH, manufactured by Union Carbide * 2: Product name: N-2301, manufactured by Nippon Polyurethane Co. Immediately before, 4.4 parts by weight of a curing agent was added and stirred. This paint is coated on a 32 μm thick polyethylene terephthalate film with a magnetic layer thickness of 4 after drying.
It was applied to both sides so as to be μ, dried and wound up. This was cured after calendering, punched out in a disk shape, and coated with a 2.0% by weight solution of a lubricant shown in Table 1 in isopropanol such that the amount of the lubricant shown in Table 1 was 600 mg / m ^2. Thus, a sample disk was prepared.

Comparative Examples 1 to 4 Sample disks were prepared in exactly the same manner as in Examples 1 to 4, except that various lubricants shown in Table 2 were used instead of the lubricants used in Examples 1 to 4.

Test Example For the sample disks obtained in Examples 1 to 4 and Comparative Examples 1 to 4, in order to examine the durability, each sample disk was stored in a shell lined with a nonwoven fabric, loaded into a recording / reproducing device, and placed on the same track. The head was run continuously. The peripheral speed at this time is 7 m / sec.

The damage of the magnetic layer of the sample disk after a certain number of passes was visually evaluated. A state without any scratches was evaluated as ◎, and thereafter, evaluation was made as △, Δ, and × in ascending order of scratches.

 Table 3 shows the results.

Claims (1)

(57) [Claims] 1. A magnetic recording medium having a magnetic layer on a nonmagnetic support, wherein the magnetic layer holds a compound represented by the following general formula (1). (Wherein, R ₁ is a hydrocarbon group having 3 to 23 carbon atoms, and R ₂ is a hydrocarbon group having 1 carbon atom.
To 20 hydrocarbon groups, R ₃ and R ₄ are hydrogen atoms or carbon atoms of 1 to 8
Represents a hydrocarbon group or a phenyl group. )