JPS61187119A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording medium having superior durability and suitability to output fluctuation by coating a substrate with a film consisting of magnetic powder, a binder and carbon black having a specified electric specific resistance, a specified volatile matter content, a specified particle size and a specified specific surface area. CONSTITUTION:Carbon black having <=0.3OMEGAcm electric specific resistance prescribed by JIS K1469, <=2% volatile matter content, <=25nm primary particle size and 100-500m<2>/g specific surface area is added to magnetic powder by 0.1-10pts.wt. per 100pts.wt. magnetic powder. They are mixed with a binder, a solvent and a lubricity providing agent, and the mixture is applied to a tape as a substrate and dried to form a magnetic tape. This magnetic tape has superior durability and suitability to output fluctuation and can maintain the effect for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium that uses a specific Kazen black and has excellent durability and running stability.

[Conventional technology]

Magnetic recording media such as magnetic tapes, which are made by coating a magnetic paint consisting of magnetic powder, binder, organic solvent, and other necessary components on a substrate such as a polyester film, are made with magnetic heads, guide members, etc. Because it runs, the magnetic layer is required to have low wear and excellent durability. Conventionally, as a measure to improve wear resistance and lubricity, it has been known to include acetylene black, by-product black, and lumberjack lubricant in the magnetic layer (for example, Japanese Patent Laid-Open No. 58-64633) Public bulletin). However, acetylene black and by-product black do not exhibit sufficient abrasion resistance, and therefore magnetic tapes using them have problems of poor durability during running and large fluctuations in output after running.

[Problem that the invention seeks to solve]

Durability due to running of magnetic tape and output fluctuation after running.

[Means for solving problems]

The present invention has an electric specific resistance of 0.3 according to J-engine 13 and 1469.
The substrate is coated with a coating film mainly composed of carmen black, magnetic powder, and a binder with a volatile content of Ωα or less, a primary particle size of 15 nm or less, and a specific surface area of 100 to 5001 rL2/g. It is a magnetic recording medium.

The carbon black for magnetic recording media used in the present invention is
Its properties are completely different from conventional Karzan black for magnetic recording media.

The karsen black used in the present invention has physical properties such as smaller electrical resistivity, lower volatile content, and smaller primary particle size, and a much larger specific surface area than conventional cursen black for magnetic ball soot books. There is. If the physical property values are outside the above range, the effect of improving the lubricity and wear resistance of the magnetic layer of the magnetic recording medium will be small, which is not preferable.

An example of a method for producing cursed black for magnetic recording media is to continuously mix acetylene gas or acetylene bus with unsaturated hydrocarbons by mixing gaseous water with oxygen etc. using a soot stream. Decomposes thermally.

In partial oxidation, if the temperature is below 500°C, the oxidation of carzen black will be insufficient and the specific surface area will not increase.

Furthermore, if hot air is supplied, the acetylene plaque will simply burn, so the amount of hot air supplied must be 1 mol or less per 1 mol of carbon black in the oxygen chamber in the hot air.

As magnetic powder, r-F1i1203, Fe3O4
, aO containing r-Fj203, CO containing 713304.0
In addition to r02 powder, 1e powder, CO powder, lPe-
Ni powder etc. can be used.

As the binder, vinyl chloride-vinyl acetate resins, vinylidene chloride resins, acrylonitrile-butadiene resins, butyral resins, urethane resins, cellulose resins, polyinocyanates, and the like are preferably used alone or in combination.

Examples of solvents include ketones such as acetone, methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone.
Ester systems such as ethyl acetate and butyl acetate, benzene,
Aromatic hydrocarbons such as toluene and xylene, acid amides such as dimethylformamide, and ethers such as tetrahydrofuran and dioxane are preferably used.

As the lubricating agent, liquid paraffin, silicone oil, etc. are used.

K for manufacturing magnetic recording media is the above-mentioned Carpin Black,
Magnetic powder, binder, solvent, and lubricating agent are blended in predetermined proportions, mixed in a mail mill, attritor sun-mill, mixer, etc., coated on a base tape, dried, and subjected to surface treatment.

Regarding each blending ratio of the magnetic recording medium, magnetic powder 100
A good ratio is 1 to 10 parts by weight of Curse 772720. If it is less than 0.1 part by weight, no effect of improving wear resistance can be obtained, and if it exceeds 10 parts by weight, the proportion of magnetic powder will be relatively reduced, resulting in a decrease in magnetic properties and a large fluctuation in output after running. S, so it is not preferable.

The blending ratio of the lubricity imparting agent is preferably 0.1 to 10 parts by weight per 100 parts by weight of the magnetic powder.

Q: If the amount is less than 13 parts by weight, the effect will not be exhibited, and if it exceeds 10 parts by weight, the lubricating agent may excessively ooze out onto the surface of the magnetic layer, contaminating the surface of the magnetic head, and reducing the output characteristics. Undesirable.

〔Example〕

Manufacturing example of Kazen black for magnetic recording media Total length of rigid type 2
．． In a pyrolysis furnace, acetylene with an inner diameter of 0.477 L% and a discharge port diameter of 0.25 m was heated. Oxygen and saturated steam (temperature 150 A mixture of 10 N7FL3/E[R] is supplied, and 18 Nm'/HR of acetylene is supplied from the outer annular part of the double tube nozzle, and the acetylene reacts with oxygen and water vapor, and then the mixture is heated at normal temperature. The acetylene plaque produced according to the method was cooled and collected.

Its physical properties are shown in Table 1 along with acetylene plaque and by-product plaque.

Table 1 Example of manufacturing a magnetic recording medium The karsand black shown in Table 1 obtained by the above method was used as a black for magnetic tape.
0 parts by weight, 80 parts by weight of the compound blended in the ratio shown in Table 2, 20 parts by weight of binder (8 parts by weight of vinyl chloride-hinyl acetate-pinyl alcohol copolymer, 12 parts by weight of polyurethane resin), 6 parts by weight of silicone oil. part and solvent 20
A magnetic paint was prepared by mixing and dispersing the mixture with 0 parts by weight (100 parts by weight of cyclohexane and 100 parts by weight of 10 methyl ethyl ketone) in an attriter (manufactured by Mitsui Miike Seisakusho Co., Ltd.) for 50 hours.

This magnetic paint was applied onto a polyester film with a thickness of 12 μm to a dry thickness of 6 μm, dried and calendered for 1 time.
A magnetic tape of 1K and a total thickness of 18μ was prepared.

Next, the durability and output fluctuation of the magnetic tape produced by the above method were measured. For comparison, the same procedure as in the example was carried out except that the conventional magnetic tape plaque shown in Table 1 was mixed.

The durability test was conducted under the conditions of 35'G and 80% RH, with a head load of 1011 and a running speed of 4.76 c.
The vehicle was regenerated by running at rtt/sea, and the number of runs until the output decreased by 3 aB from the initial output was measured.

Further, the output fluctuation was measured by running the magnetic tape under the same conditions as in the durability test and measuring the output fluctuation at the initial stage and after running 200 times.

The various materials used in the Examples and Comparative Examples are as follows.

(1) Magnetic powder (a) Co-magnetic acid [arsenic... (Co-r-P
8203 series powder, surface area 23 m”/11) (o) r -Ffs 203 powder...Surface area 18
m”/ 1 (2) Binder (a) Vinyl chloride-vinyl acetate...Denki Kagaku Kogyo (To-Vinyl alcohol copolymer product name "Denka Vinyl-10000KT") (B) Polyurethane resin...Product name manufactured by Nippon Polyurethane "Coronate L" (3) Lubricity imparting agent (a) Silicone oil... Toshiba Silicon Co., Ltd. developed product name "T8M 600 J [Effects of the invention] The magnetic recording medium obtained by the present invention has excellent durability. The output fluctuation after the first run is small, and these effects are maintained over a long period of time.

Claims (1)

[Claims] Electrical specific resistance 0.3Ωcm or less according to JISK1469, volatile content 2% or less, primary particle size 25nm or less, specific surface area 10
A magnetic recording medium characterized in that a coating film containing 0 to 500 m^2/g of carbon black, magnetic powder, and a binder as main components is provided on a substrate.