JPS58141440A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve durability by contg. an extreme pressure agent in the magnetic coating film wherein fatty acid ester and fatty acid are used as a lubricant. CONSTITUTION:An extreme pressure agent is further contained in a magnetic coating film wherein fatty acid ester and fatty acid are used as a lubricant. The strength of the oil film of the lubricating film formed on the surface of the magnetic coating film is thus improved, whereby the abrasion resistance of the magnetic coating film is significantly improved and the durability thereof is improved. All of known extreme pressure agents of phosphorus-, sulfur-, halogen- and organometallic types used for general lubricating materials are usable as the extreme pressure agent. The phosphorus type extreme pressure agents are more particularly preferable among these extreme pressure agents, for which phosphates such as tricresyl phosphate and phosphites such as trilauryl phosphite are preferable. The amt. of the extreme pressure agent to be used is generally about 0.1-10pts.wt. based on 100pts.wt. total weight of fatty acid ester and fatty acid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to magnetic tapes and other magnetic recording media using fatty acid esters and fatty acids as lubricants for magnetic coatings, and an object thereof is to provide magnetic recording media with improved durability. It is about doing.

Since the durability of magnetic tapes and the like mainly depends on the abrasion resistance of the magnetic coating film provided on the substrate, various efforts have been made to improve this abrasion resistance.

One known example is a magnetic coating containing a fatty acid ester and a fatty acid as a lubricant.

This type of lubricant forms a good lubricating film on the surface of the magnetic coating from low to high temperatures, and prevents the magnetic coating from being worn out by the sliding contact of the magnetic head. Since the oil film strength determined by the formula friction test is generally about 2 kg/CI#, there is a problem that it cannot sufficiently resist long-term sliding wear.

As a result of intensive studies to overcome the above problems, the inventors discovered that when an extreme pressure agent is further included in a magnetic coating film that uses fatty acid esters and fatty acids as lubricants, formation of The oil film strength of the lubricating film is about 7
It has been found that the abrasion resistance of the magnetic coating film can be greatly improved by increasing Kl/d or more, and a magnetic recording medium with excellent durability can be obtained.

As the above-mentioned extreme pressure agent, any known extreme pressure agent such as phosphorus type, sulfur type, phosphor type, organometallic type, etc. used in general lubricating materials can be used.

Examples of phosphorus-based extreme pressure agents include phosphates and phosphites. Sulfur-based extreme pressure agents include sulfur, diphenyl sulfide, diphenyl sulfide, diphenyl sulfide, and other sulfides, as well as sulfurized oils and fats, and thiocarbonates. In addition, chlorinated hydrocarbons and chlorinated carboxylic acid derivatives such as halogenated extreme pressure agents, monochlorobenzene, pentachlorodiphenyl, hexachloroethane, methyl trichlorostearate, and methylpentachlorostearate, as well as various iodine compounds. There are also fluorine compounds. Furthermore, organometallic extreme pressure agents include metal salts of naphthenic acid and fatty acids, metal salts of thiophosphoric acid, metal salts of thiocarbamic acid, titanium compounds, tin compounds, germanium compounds, boromine compounds, silicon compounds, etc. Can be mentioned.

Among these first extreme pressure agents, phosphorus extreme pressure agents are particularly preferred, including tricresyl phosphate, trilauryl phosphate, monoamyl phosphate, polyoxyalkylene ether phosphate, and amine-
Phosphates such as phosphate ester reactants and phosphites such as trilauryl phosphite, dilauryl phosphite, and tribunal phosphite are preferably used.

The amount of extreme pressure agent used is generally about 0.1-10 parts by weight per 100 parts by weight of the total amount of fatty acid ester and fatty acid. I can't hope for improvement.

The fatty acid ester used as one of the lubricants in this invention may be any conventionally known fatty acid ester, and usually has 12 to 1 carbon atoms.
An ester of 8 monobasic fatty acids and m alcohols having 1 to 15 carbon atoms is used.

In addition, the fatty acid used in combination with the fatty acid ester enhances the lubricating effect of the fatty acid ester, and is a component that brings about good results in lubricity especially at high temperatures, and generally has a carbon number of 1.
2-1B monobasic fatty acids are preferably used.

The ratio of fatty acid ester and fatty acid used is in the range of 0.1 to 20 parts by weight per 100 parts by weight of magnetic powder, and the ratio of fatty acid in the total amount, that is, fatty acid/(fatty acid ester + fatty acid) xiOO (wt%
) is preferably in the range of 25 to 75% by weight.

Any method may be used to incorporate the fatty acid ester, fatty acid, and extreme pressure agent into the magnetic coating, for example, by spraying a bath liquid in which each of the above components is dissolved on the surface of the magnetic coating provided on the substrate. Any appropriate method may be employed as needed, such as a method of impregnating the magnetic material with a magnetic material, or a method of dissolving and dispersing the above-mentioned components in a magnetic paint and applying it onto a substrate to form a magnetic coating film.

Examples of the present invention will be described below. In the following,
Parts shall mean parts by weight.

Example 1 800 parts of ω-containing γ-'e zOa powder, 80 parts of nitrocellulose (H1/2), Crysbon 7209 (980 parts of polyurethane resin manufactured by Inu Nippon Ink Chemical Industry Co., Ltd., Coronay) L (manufactured by Nippon Polyurethane Industry Co., Ltd.) polyfunctional incyanate compound] 40 parts, carbon black 50 parts,
A magnetic paint was prepared by mixing 7 parts of stearin (n-butyl), 5 parts of palmitic acid, 0.15 parts of trilauryl phosphate, 850 parts of toluene, and 7850 parts of methyl ethyl chloride in a ball mill.

This paint was applied to a polyester film with a thickness of 15 μm to a thickness of 5 μm, dried, mirror-finished, and cut to a predetermined width to obtain the magnetic tape of the present invention.

Comparative Example 1 Trilauryl phosphate was used (except for 1)
A magnetic tape was produced in the same manner as in Example 1.

Example 2 G content 1 - Metallic iron powder 800 instead of Fe2g3 powder
Also, nitrocellulose (Hl/2) COD VA
Magnetic tapes were produced in the same manner as in Example 1, except that GH (vinyl chloride-vinyl acetate-vinyl alcohol copolymer resin manufactured by U, C, C Company) 809 was used.

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 2 except that trilauryl phosphate was not used.

Each of the magnetic tapes of the above Examples and Comparative Examples was heated at 40°C using a Hiteo Deck (Newly manufactured by Hitachi V"'8000).
The results of repeated running tests under a 280% RH environment are as shown below. Here, durability is expressed as the number of runs until the video S/N drops by 3 dB from the initial value.

As is clear from the above test results, the magnetic tape of the present invention is found to be extremely durable compared to conventional magnetic tapes.

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Claims (1)

[Claims] A magnetic recording medium characterized in that an extreme pressure agent is contained in a magnetic coating film using an il+ fatty acid ester and a fatty acid as a lubricant.