JPS62164216A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the durability and traveling stability of the titled magnetic recording medium by incorporating three kinds of specified esters into the magnetic coated film as a lubricant. CONSTITUTION:(A) An aliphatic monobasic acid ester, (B) an aliphatic dibasic acid diester, and (C) a phosphoric trialkyl ester are incorporated into the mag netic coated film on a carrier as a lubricant. An (un)saturated 12-18C fatty acid ester which is liq. at room temp. (e.g., n-butyl stearate) is preferably used as the component A. The ester of a <=18C (un)saturated alcohol and a <=10C aliphatic dibasic acid which is liq. at room temp. (e.g., dioleyl diadipate) is preferably used as the component B. The ester of a 14-20C saturated alcohol and phosphoric acid which is liq. at room temp. (e.g., tritetradecyl phosphate) is preferably used as the component C. With this constitution, the magnetic recording medium having excellent durability and traveling stability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium used as a magnetic tape or a floppy disk, and particularly to a magnetic recording medium with improved durability and running stability.

Conventional technology Magnetic recording media have traditionally been made by coating magnetic paint on a support such as a polyester film, but because of the sliding contact with magnetism and RAD, highly durable magnetic recording media have been used. In addition to performance, driving stability is also required. For this reason, the selection of the lubricant to be added to the magnetic coating is extremely important. Examples of conventionally used lubricants include fatty acid esters, liquid hydrocarbons, silicone oils, and fluorine oils.
923, Japanese Patent Application Laid-Open No. 52-49803, etc. are known.

Problems to be Solved by the Invention However, with the above configuration, if the amount of lubricant added is increased with emphasis on durability, problems may arise in running performance. This problem is particularly problematic when magnetic recording media have a highly smooth surface, such as high-density double-sided floppy disks.
Moreover, this problem was more likely to occur when there was sliding contact with the magnetic head over a wide surface. For example, when a magnetic recording medium and a magnetic head are in stationary contact for a long time, the liquid lubricant layer present on the surface of the magnetic recording medium adheres to the two, significantly increasing the starting torque.5 There is a thing.

In view of the above problems, the present invention provides a magnetic recording medium with improved durability and running stability.

Means for Solving the Problems In order to solve the above problems, the magnetic recording medium of the present invention has the following features:
The magnetic coating film contains at least three types of lubricants: an aliphatic monobasic acid ester, an aliphatic dibasic acid diester, and a phosphoric acid trialkyl ester.

The aliphatic monobasic acid ester used in the present invention is preferably an ester of saturated or unsaturated fatty acids having 12 to 18 carbon atoms that is liquid at room temperature, such as n-butyl myristate.

inamyl palmitate, inpropyl stearate,
n-butyl stearate, n-butyl oleate.

Examples include oleyl oleate.

Next, as the aliphatic dibasic acid diester, carbon number 18
A diester consisting of the following saturated or unsaturated alcohol and an aliphatic dibasic acid having 10 or less carbon atoms, which is liquid at room temperature is preferable, examples of which include dioleyl malate and dioleyl succinate. , dioleyl adipate, dioleyl sebacate, diindecyl maleate, diindecyl succinate, diindecyl adipate, diincetyl adipate, diisostearyl adipate, and the like.

Next, the phosphoric acid trialkyl ester used in the present invention is a triester consisting of a saturated aliphatic alcohol having about 14 to 20 carbon atoms and phosphoric acid. Sadecyl phosphate.

Examples include tristearyl phosphate. These exhibit a solid state at room temperature.

The mixing ratio of aliphatic monobasic acid ester and aliphatic dibasic acid diester used in the present invention is preferably in the range of 20:80 to 80:20, and the ester mixture 100:
The amount of trialkyl phosphate is preferably 1 to 30 parts per part, and the total amount of lubricant per 100 parts of magnetic powder is 3 to 15 parts.
Approximately 100% is appropriate.

Function In the present invention, the aliphatic monobasic acid ester and the aliphatic dibasic acid diester used significantly improve the durability of the magnetic coating film against magnetic sliding.

Among the above two types of esters, aliphatic monobasic acid esters such as n-butyl stearate have the property of being relatively easily included inside the binder and have an internal lubricating effect, whereas aliphatic monobasic acid esters such as dioleyl adipate Basic acid diesters have the properties of being relatively easy to release to the outside and having a strong oil film.

Therefore, a magnetic coating film using both of them has excellent sliding durability even under a wide range of environmental conditions.

However, when such a magnetic coating is used in a high-density double-sided floppy disk, if the amount of ester compounded is increased to improve durability, a liquid lubricant oozes out on the surface of the magnetic coating, which damages the magnetic head. A phenomenon often occurred in which the starting torque became significantly high due to adsorption.

In the present invention, a phosphoric acid trialkyl ester is further added to the above-mentioned 2s ester, thereby suppressing the above-mentioned increase in starting torque. Although the details of the mechanism are not fully clear, the above-mentioned phosphoric acid trialkyl ester is present in trace amounts as ultrafine solid particles on the surface of the coating film, and this significantly reduces the friction coefficient of the coating film. This is thought to suppress the attraction of the magnetic head and the increase in starting torque. In this case, if the amount of phosphoric acid trialkyl ester is too small, the above effect will be small, and conversely, if it is too large, the amount of solid particles present on the surface of the magnetic coating will increase, making it easier to cause problems such as missing tracks. There is a risk of deteriorating quality.

Next, these three types of esters can be added to magnetic paint to obtain the above effects, but another method is to dissolve the above esters in a suitable solvent such as trichlorotrifluoroethane. It is also possible to apply it to a magnetic coating film by applying it, spraying it, dipping it, etc.

As described above, the present invention provides a magnetic recording medium with the above-described structure ensuring durability and running stability.

Examples Examples of the present invention will be described below. In the Examples, all parts are by weight.

To 7-7 Example 1 100 parts of cobalt-magnetized iron oxide, 12 parts of nitrified cotton (manufactured by Asahi Kasei Industries, Ltd., trade name 5L-1), 16 parts of polyurethane resin (manufactured by Nippon Polyurethane Industries, Ltd., trade name N-2301) , 2 parts of 1/cythene, 6 parts of carbon black, 4 parts of alumina powder, 2 parts of n-butyl stearate, 5 parts of dioleyl adipate, 0.7 parts of tristearyl phosphate, 140 parts of toluene, 140 parts of methyl ethyl ketone, cyclohexanone After mixing 90 parts in a ball mill for 12 hours, 5 parts of a polyinsyanate compound (manufactured by Nippon Polyurethane Kogyo Co., Ltd., trade name: Coronet L) was added and mixed well.The resulting magnetic paint was applied to both sides of a 76 μm thick polyester film. , after coating to a dry coating thickness of 1.3 μm and smoothing the surface by calendering,
The original fabric was obtained by heating and curing at 60°C for 124 hours.

Example 2 In Example 1, the lubricants used were 4 parts of n-butyl oleate, 3 parts of dioleyl adipate, and 1 part of tristearyl phosphate, and all other conditions were the same to prepare a prototype fabric.

Examples 3 to 10 In Example 1, original fabrics were produced as prototypes, with only the type and blending ratio of the lubricant used being varied, and other conditions being the same. The contents are shown in Table 1 below together with Example 1.2.

Comparative Examples 1 to 1゜In Example 1, one or two types of lubricant were used,
The other conditions were the same, and a prototype of Gogenban was produced.

The contents are shown in Table 2 below.

(Margins below) 9 to 10 pages 11 pages The original fabrics obtained in the above Examples and Comparative Examples were punched out into disk shapes, the surfaces of which were polished, and then inserted into a case to form a floppy disk. This disk has a head pressure of 47,5.9
Loaded into a double-sided drive heated to 5℃, 40% R, H,
and 40'C, 80% R,H.

An accelerated durability test was conducted. Also, 25°C16o
% R, H, the above disk was loaded into a double-sided drive, driven for 3 minutes, stopped for 10 minutes 'ff: 10 cycles were repeated, and the rate of change was calculated from the starting torque measurements before and after the test. We also checked the presence or absence of missing pulses and extra pulses, and checked the quality of the track and link. The results are summarized in Table 3 below.

(Left below) (Table 3) Characteristics of Examples and Comparative Examples 13 bases. As is clear from the results in Table 3, the lubricant formulation conditions shown in the Examples result in low temperature, low humidity, high temperature and high temperature. It can be seen that a disk with good acceleration durability under humid conditions, starting torque increase rate, and track quality can be obtained.

On the other hand, as shown in the comparative example, when only one or two of the three aliphatic monobasic acid esters, aliphatic dibasic acid diesters, and phosphoric acid trialkyl esters are used, all of the above characteristics are achieved. It turns out that it is difficult to satisfy both at the same time.

Effects of the Invention As described above, according to the present invention, a magnetic coating containing at least three types of lubricants: an aliphatic monobasic acid ester, an aliphatic dibasic acid diester, and a trialkyl phosphate ester is used. By forming a film on a support, a magnetic recording medium with high durability, running stability, and reliability under a wide range of environmental conditions can be obtained.

Claims (1)

[Claims] Magnetic recording characterized in that a magnetic coating film containing at least three lubricants, an aliphatic monobasic acid ester, an aliphatic dibasic acid diester, and a phosphoric acid trialkyl ester, is formed on a support. Medium.