JPH052735A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To impart good libricity to the above-mentioned medium and to great ly improve its durability by using a fatty acid having the branched chain expressed by specific formula as a lubricant. CONSTITUTION:The branched fatty acid expressed by the formula is incorporated into the magnetic layer on a nonmagnetic base. The branched fatty acid is produced by the addition reaction of olefin and fatty acid. As the olefin, 6 to 32C, more preferably 6 to 28C alpha-olefins are used. As the fatty acid, 6 to 26C caproic acid, caprilic acid, lauric acid, mysistic acid, malmitic acid, stearic acid, etc., are used as the fatty acid. The charging quantity of the olefin in the above-mentioned reaction is specified to 50 to 60mol% of the fatty acid. An org. peroxide as a radical generating agent, such as dialkyl peroxide or tertiary butyl perioxide, is used at the time of the addition reaction. The branched fatty acid is used at 1 to 15 pts. wt., more preferably 3 to 10 pts.wt. in total per 100 pts.wt. magnetic powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium having excellent durability.

[0002]

2. Description of the Related Art A magnetic recording medium slides violently on a magnetic head or a pad during recording and reproduction, and the magnetic layer is easily abraded. What is desired is desired. Therefore, as a measure for improving the wear resistance of the magnetic layer, an internal addition method of mixing various lubricants into the magnetic layer, a top coat method of forming a lubricating layer on the surface of the magnetic layer, or the like is performed.
Conventionally used lubricants include fatty acid amide, liquid paraffin, silicone oil and the like. However, at present, it is difficult to say that these lubricants are satisfactory in terms of performance.

[0003]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied to obtain a magnetic recording medium having good lubricity and greatly improved durability. As a result, a fatty acid having a branched chain was used as a lubricant. They have found that the object can be achieved by using them and have reached the present invention.

That is, the present invention provides a magnetic recording medium having a magnetic layer on a non-magnetic support, wherein the magnetic layer has the following general formula:
(I)

[0005]

[Chemical 2]

The present invention provides a magnetic recording medium characterized by containing a branched fatty acid represented by:

Since the branched fatty acid used in the present invention has a branched chain as compared with the fatty acid conventionally used for manufacturing a magnetic recording medium, it has excellent low temperature fluidity, hydrolysis resistance, and
Compatibility and heat resistance can be imparted to the magnetic recording medium.

The branched fatty acid represented by the general formula (I) used in the present invention is, for example, Izv. Akad. Nauk. SSSR, 1961 ,
It can be produced by the addition reaction of an olefin and a fatty acid described in 1487. Examples of the olefin used here include α-olefins having 6 to 32 carbon atoms, preferably 8 to 28 carbon atoms. Examples of fatty acids include fatty acids having 6 to 26 carbon atoms such as caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid and stearic acid. When the total number of carbon atoms in the branched fatty acid is 18, R ₁
It is preferable that the carbon numbers of R ₂ are even. The amount of the olefin charged in the above reaction is preferably 50 to 60 mol% of the fatty acid, and in the addition reaction of the olefin, an organic peroxide is used as a radical generator such as dialkyl peroxide and tertiary butyl peroxide. It is desirable to do.

The branched fatty acid according to the present invention is a magnetic powder.
The total amount is 1 to 15 parts by weight, preferably 3 to 10 parts by weight.
It is preferred to use parts by weight. If desired, they may be used in combination with other general-purpose lubricants, for example, esters such as butyl stearate, fatty acids other than the present invention such as oleic acid, and hydrocarbons such as squalane.

The branched fatty acid (I) according to the present invention is impregnated in the coating film by mixing it in the magnetic coating material in advance, or by coating a solution of a general-purpose solvent such as isopropanol or hexane after forming the magnetic coating film and drying it. Can be used. Further, a medium formed by forming a magnetic layer on a non-magnetic support by sputtering or vapor deposition can also be applied by the same method and used.

The magnetic powder used in the magnetic recording medium of the present invention includes needle-shaped fine metal oxides such as γ-Fe ₂ O ₃ , Fe ₃ O ₄ and CrO ₂ , and Co-deposited γ-. Fe ₂ O ₃ , Co-doped γ-Fe
₂ O processing alms was gamma-Fe ₂ O _3, such as _3, metallic iron powder, a portion of the platelet-shaped barium ferrite and Fe atoms Ti, Co, Zn, V, 1 or such as Nb or Examples include magnetic powders substituted with two or more kinds, and ultrafine powders of metals or alloys such as Co, Fe—Co, Fe—Ni. Of these, metallic iron powder is particularly poor in chemical stability and, for this improvement, nickel, cobalt, titanium, silicon, aluminum, etc. may be added in small amounts in the form of metal atoms, salts and oxides or may be surface-treated. However, these can also be used. The metallic iron powder may form a thin oxide film on the surface in a weak oxidizing atmosphere due to its stabilization, but the metallic powder treated in this way can also be used. Further, two or more kinds of the above magnetic powder may be mixed and used.

Examples of the binder used in the present invention for dispersing magnetic powder to form a magnetic layer include:
Polyurethane resin which may have metal sulfonate base, polyvinyl chloride, vinyl chloride vinyl acetate copolymer, polyacrylonitrile, nitrile rubber, epoxy resin, alkyd resin, polyamide, polyacrylic acid ester, polymethacrylic acid ester , Polyvinyl acetate, polyvinyl butyral, vinylidene chloride, nitrification cotton, maleic acid-modified vinyl chloride / vinyl acetate copolymer, ethyl cellulose and the like. Even if these are used alone, 2
You may use it in mixture of 2 or more types. In addition, a plasticizer or a curing agent may be added to adjust the hardness of the resin.

In addition to the above components, the magnetic layer of the magnetic recording medium of the present invention may contain additives commonly used in this field such as an abrasive and an antistatic agent.

The non-magnetic support used in the production of the magnetic recording medium of the present invention includes polyesters such as polyethylene terephthalate; polyolefins such as polyethylene and polypropylene; cellulose derivatives such as cellulose triacetate and cellulose diacetate;
Polycarbonate; polyvinyl chloride; polyimide; plastics such as aromatic polyamide; metals such as Al and Cu; paper and the like. 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 rays or the like, or may be precoated with a suitable resin.

[0015]

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

Example 1 Co Coated γ-Fe ₂ O ₃ 100 parts by weight Nitrocellulose ^{* 1} 12 〃 Polyurethane resin ^{* 2} 12 〃 Branched fatty acid 8 〃 Carbon black 10 〃 (single average particle size 20 nm) Alumina 10 〃 ( Single average particle size 0.55μ) Toluene / Cyclohexa 100/100 / 100〃 Sanon / Methyl ethyl ketone Note) * 1: Asahi Kasei Corporation's Sernova BTK 1/8 * 2: Toyobo Co., Ltd. sodium sulfonate group Polyurethane Resin Containing The above composition was kneaded in a sand mill for about 6 hours, 6 parts by weight of a curing agent (Coronate L from Nippon Polyurethane Industry Co., Ltd.) was added, and the mixture was stirred to form a polyethylene terephthalate film having a thickness of 75μ. The coating was applied so that the dry film thickness was 1.0 μm. After that, calendering was performed, and then the material was punched into a disk shape to polish the surface of the magnetic layer. After that, 60 ℃, 15%
Leave it in the environment of RH for 24 hours and put it in a jacket
I used a 3.5-inch floppy disk. In the coating composition, the branched fatty acid is represented by the general formula (I) in which R ₁ and R ₂ are both C ₁₀ H _21-
Was used. This floppy disk was loaded into a drive and the abrasion resistance was tested by the following method. [Abrasion resistance test method] Remove the head part above the drive unit and place a SUS 304 steel ball with a diameter of 1/4 inch instead. A floppy disk was loaded into the drive unit modified in this way, and 5 ℃, 65% RH, 20 ℃, 50% RH and 60 ℃, 15
Drive each for 10 minutes in the environment of% RH. Since the surface of the magnetic layer is abraded by the steel balls, the width of abrasion was measured after the test and used as a measure of abrasion resistance. That is, the lower the lubricity of the surface, the larger the contact area between the steel ball and the magnetic layer and the larger the width of wear. The results are shown in Table 1.

Examples 2 to 4 and Comparative Examples 1 and 2 Floppy disks were prepared by using various compounds shown in Table 1 in place of the branched fatty acid in the magnetic coating material of Example 1, and the same tests were conducted. The results are shown in Table 1.

[0018]

[Table 1]

Claims (1)

Claim: What is claimed is: 1. A magnetic recording medium having a magnetic layer on a non-magnetic support, wherein the magnetic layer has the following general formula (I): A magnetic recording medium containing a branched fatty acid represented by: