JPS62212927A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To eliminate head attraction even after abuse use by incorporating a phosphate, fatty acid of 14-18C and fatty acid ester of 28-36C at a specified ratio into a magnetic layer and incorporating carbon black having the particle size different from the particle size of a lubricating agent component therein so that the carbon black exists partly on the medium surface. CONSTITUTION:A material prepd. by adding adding 1:2-1:4 total of of the phosphate and the fatty acid of 14-18C and the fatty acid ester of 28-36C to said material, adding <=60mmu carbon black thereto and further incorporating >=60mmu carbon black therein is further kneaded together with magnetic powder and binder to form the magnetic layer. The long-period durability from a low temp. and low humidity to a high temp. and high humidity is thereby improved and the attraction of the medium and head to each other is suppressed. The magnetic recording medium which permits smooth starting is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a magnetic material that can improve long-term durability from low temperature and low humidity to high temperature and high humidity, and that enables smooth rotational drive without adhesion between the medium and the head in the same environment. Regarding recording media.

Conventional technology 2 - Traditionally, in magnetic recording media such as floppy disks, the magnetic layer is in sliding contact with the magnetic head or liner material during rotation, and this friction causes the disk surface to wear out, making it difficult to use for long periods of time. On the other hand, damage and peeling of the magnetic layer occur, making recording and reproducing impossible. In order to improve this durability, it is important to reduce the frictional resistance of the magnetic layer and to form a boundary lubricant layer on the surface of the medium. For this reason, it has been proposed that the magnetic layer contain various lubricants such as higher fatty acids or esters thereof.

Problems to be Solved by the Invention However, although these lubricants can achieve excellent durability during continuous use by reducing frictional resistance and forming a uniform boundary lubrication layer, During intermittent use, an adhesion phenomenon occurs between the two, which significantly increases the starting torque of the drive rotary machine, and in the worst case, it may not be possible to start, making it impossible to sufficiently suppress the head adsorption phenomenon. It had a point.

In view of the above-mentioned problems, the present invention has been developed to reduce the temperature from low temperature and low humidity to high temperature 3.
7. It is an object of the present invention to provide a magnetic recording medium that has long-term durability under high humidity conditions and can be started smoothly without any adhesion phenomenon between the medium and the head.

Means to Solve the Problem The present invention contains a phosphoric acid ester, a fatty acid having 14 to 18 carbon atoms, and a fatty acid ester having 28 to 36 carbon atoms in a constant ratio, and has a particle size different from that of the lubricant component. It has a structure in which a carbon blank is contained and partially present on the surface of the medium.

Operation The present invention provides a magnetic recording medium with the above-described structure, which has no head adhesion phenomenon even during continuous use from low temperature and low humidity to high temperature and high humidity, or severe intermittent use, and has stable driving and excellent durability.

EXAMPLES Below, magnetic recording media according to examples of the present invention will be described.

Example 1 A, Cobalt-adhered magnetic iron oxide 100 (unit weight part) B1 Carbon black (particle size 40 mμ) 3.5 Carbon black (particle size 90 mμ) 3.5 (unit weight part) C Lucitin 0.6D1
Urethane prepolymer 14E1 cellulose 14F1 oleyl oleate
5G1 stearic acid 1
．． 5μ1 granular alumina (particle size 0.5μ) 4■, polyisocyanate 611 methyl isobutyl ketone 200 (C + G): (F) = 1:
2.5 These compositions are kneaded in a ball mill to make a magnetic paint, and then applied to a 75μ thick polyester film with a dry thickness of 1.
．． It was coated on both sides to a thickness of 2 μm, dried, and calendered, then cured and punched out into a 3-inch disk shape to produce a floppy disk.

B, C, F from the paint composition in Example 1.

Floppy disks were prepared in the same manner except that G was changed as shown in the example shown in the table below.

(Hereinafter referred to as Ta, blind) Go to 5-2 61,7 The floppy disks obtained in each example and each comparative example were assembled into a case and heated to room temperature and
The head adsorbed carbon and O
'C durability test was conducted.

When the head adsorbing carbon was driven at 50% or less of the rated voltage, good binding of 60% to 76 inches was allowed, and anything above that was not allowed. Durability was determined by measuring the number of buses until the average signal amplitude reduction rate reached 30 inches. Table 2 shows the results.

(For ν'kT, as is clear from Table 2, magnetic layers with a small amount of fatty acid ester have poor durability, and those with a large amount have good durability but head adsorption is observed.Also, fatty acids and phosphoric acid It can be seen that those with a large total amount of ester have poor durability but less head adsorption.In order to satisfy both head adsorption and durability, the mixing ratio of the total amount of phosphoric acid ester and fatty acid to the fatty acid ester must be ~%. % range, it can be achieved as in Examples 1-6.

In addition, the ratio of phosphoric acid ester, fatty acid having 14 to 18 carbon atoms, and fatty acid ester having 28 to 36 carbon atoms is such that the total weight of phosphoric ester and fatty acid and the polymerization of fatty acid ester are 1=2.
The ratio of phosphoric acid ester to fatty acid is preferably in the range of ~1:4. If the ratio of phosphate ester and fatty acid is too small, the dispersibility of the magnetic powder will be poor, resulting in poor electromagnetic conversion characteristics such as modulation and resolution S/N. If it is too large, the magnetic layer will deteriorate. This reduces the adhesiveness and strength of the base film, resulting in poor durability. If the proportion of fatty acid ester is too small, sufficient low-temperature durability cannot be obtained, and although the head adsorption phenomenon at high temperature and high humidity can be alleviated, it cannot be sufficiently suppressed. On the other hand, if the amount is too large, the durability will be improved, but the head adsorption phenomenon will be worsened.

As with conventional carbon black, it is sufficient to use particles with a particle size of 60 mm or less for the purpose of preventing static electricity.
Thin magnetic layers for high-density recording require a large amount of carbon black to reduce light transmittance, and those with small particle diameters also absorb large amounts of oil, reducing binder strength and durability. . Particles with a diameter of 60 millimicrons or more are not very effective in reducing surface electrical resistance, but tend to be effective in suppressing light transmittance, and when used together, the transmittance is 1, the surface resistance is lower, and the binder strength is lower. It has the effect of balancing the The effect of the combined use is to suppress the head adsorption phenomenon by making some of these exist on the surface of the magnetic layer. If only 60 mm or less, the head adsorption phenomenon cannot be sufficiently suppressed, but if 60 mm or more is used together, the starting torque will not increase and the adhesion prevention will be further improved.

The fatty acid ester used in the present invention has a volatility of 10'.
-/ Low, liquid to solid at room temperature, forms a boundary lubrication layer on the surface of the medium and exhibits excellent durability.

Fatty acid esters having 28 to 36 carbon atoms are preferred as they have an excellent lubrication effect, and examples of such fatty acid esters include esters of fatty acids having 14 to 18 carbon atoms and aliphatic alcohols having 14 to 18 carbon atoms. Fatty acids include myristic acid and valmitic acid.

These are stearic acid and oleic acid, and examples of aliphatic alcohols include myristyl alcohol, cetyl alcohol, stearyl alcohol, and oleyl alcohol.
Preferably, esters are combinations of these, such as myristyl stearate, myristyl oleate, and cetyl stearate.

Examples include cetyl oleate, oleyl oleate, oleyl stearate, and stearyl palmitate.

Examples of fatty acids include myristic acid, palmitic acid, stearic acid, oleic acid, and the like.

Examples of phosphoric acid esters include lecithin and phosphates of various fatty acids.

11'h-5 Effects of the Invention As described above, the present invention adds a total of a phosphoric acid ester and a fatty acid having 14 to 18 carbon atoms to a fatty acid ester having 28 to 36 carbon atoms in a ratio of 1=2 to 1:1 to the magnetic layer. By adding a carbon blank of 60 millimicrons or less or adding carbon black of 60 millimicrons or more to this and kneading it with magnetic powder and a binder to form a magnetic layer, it can be used in environments ranging from low temperature and low humidity to high temperature and high humidity. A magnetic recording medium can be obtained that has improved long-term durability, suppresses the media-hesode adsorption phenomenon, and enables smooth startup.

Claims (1)

[Claims] Phosphate ester, fatty acid with 14 to 18 carbon atoms, and 2 carbon atoms
The magnetic layer includes a magnetic layer containing a fatty acid ester having 8 to 36 carbon atoms and carbon black, and the magnetic layer has a ratio of the total weight of the phosphate ester and the fatty acid having 14 to 18 carbon atoms to the weight of the fatty acid ester of 1:2 to 1:2. A magnetic recording medium characterized in that the ratio is 1:4 and the particle size of carbon black is two or more types, one of 60 millimicrons or more and one of 60 millimicrons or less.