JPS62165727A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve durability and running stability by incorporating at least 3 kinds of an aliphat.-basic acid ester, glycerol triester and trialkyl phosphate as a lubricating agent into a magnetic coated film. CONSTITUTION:The magnetic coated film for which both the aliphat.-basic acid ester and glycerol triester are used in combination has excellent sliding durability under wide environmental conditions. However, the liquid lubricating agent bleeds on to the surface of the magnetic coated film and is adsorbed onto a magnetic head and the consequent increased starting torque is caused if the amt. of the ester to be compounded is increased in order to improve the durability in the stage of using such magnetic coated film for a high-density double-faced floppy disk. The increase of the starting torque is, thereupon, suppressed by further adding the trialkyl phosphate to two kinds of the esters. The durability and running stability are assured by such constitution.

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. At the same time, driving stability is required. For this reason,
The selection of the lubricant added into the magnetic coating is extremely important. There are various types of lubricants that have been used in the past, such as fatty acid esters, liquid hydrocarbons, silicone oils, and fluorine oils. Showa 52-498
Publication No. 03 is 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 period of time, a phenomenon can be observed in which the liquid lubricant layer present on the surface of the magnetic recording medium adheres to the two, significantly increasing the starting torque. be.

The present invention addresses the above problems and 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 uses at least three types of lubricants: aliphatic-basic acid esters, glycerin triesters, and phosphoric acid trialkyl esters.
The type is contained in a magnetic coating film.

The fat-acid basic 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, isopropyl stearate),
n7” chillsteare), n7” chillolate.

Examples include oleyl oleate.

Next, the glycerin triester is preferably a triester consisting of glycerin and a saturated or unsaturated fatty acid having 6 to 18 carbon atoms, which is liquid at room temperature, such as glyceryl tricaprylate, glyceryl tricaprate, Examples include glyceryl-1-oleo-2,3 cicaprelate, glyceryl triolate, glyceryl-2-oleo-1.3 dilaurate, and glyceryl-1-myristo-2.3 diolaate.

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. Decyl phosphate.

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

The blending ratio of aliphatic-basic acid ester and glycerin triester used in the present invention is preferably in the range of 20:80 to 80:20, and the ester mixture 100:
1 to 30 parts of phosphoric acid trialkyl ester per part, and the total amount of lubricant (per 100 parts of magnetic powder) is 3 to 1 part.
Approximately 6 copies is appropriate.

Function: In the present invention, the aliphatic-basic acid ester and glycerin triester used significantly improve the durability of the magnetic coating against sliding of the magnetic head. Among the above two types of esters, aliphatic-basic 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 glycerin triesters such as glyceryl triolate It has the properties that it is relatively easy to come out and has a strong oil film. Therefore, a magnetic coating film that uses both in combination 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 in which the starting torque becomes significantly high due to adsorption often occurs.

In the present invention, a phosphoric acid trialkyl ester is further added to the above two types of esters, thereby suppressing the above-mentioned increase in starting torque. Although the details of the mechanism are not sufficiently clear, the above-mentioned phosphoric acid trialkyl ester exists in trace amounts as ultrafine solid particles on the surface of the coating film, and this significantly lowers the coefficient of friction of the coating film, causing the magnetic head to This is thought to suppress the rise in adsorption and starting torque. In this case, if the amount of phosphoric acid trialkyl ester blended 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, which will prevent the occurrence of missing pulses, etc. This may reduce track quality.

Next, these three types of esters can be added to magnetic paint to obtain the effects described above, but another method is to dissolve the above esters in a suitable solvent such as trichlorotrifluoroethane. It is also possible to apply, spray, immerse, etc. a solution on the magnetic coating film.

In this way, the present invention achieves durability and [
This provides all magnetic recording media with guaranteed running stability.

EXAMPLES The implementation of the present invention will be described below. During the implementation process,
All parts are by weight.

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), l/city /2 parts, carbon black 5 parts, alumina powder 4 parts, n-butyl stearate 2 parts, glyceryl triolate 6 parts, tristearyl phosphate 1.1 part, toluene 140 parts, methyl ethyl ketone 140 parts, cyclohexafluoride 90 parts After heating for 12 hours in a Zeel mill, 5 parts of a polyinsyanate compound (Japan Polyurethane Industries Co., Ltd. model, trade name Kopne L) was added and mixed well to make a magnetic paint. The coating was applied to both sides so that the dry coating thickness was 1.3 μm, and the entire surface was smoothed by calendering, and then heated and cured at 60'C for 24 hours. Experimental rows 2 to 1. At the practical pH, only the type and blending ratio of the lubricant used were varied, and other conditions were kept the same, and prototype fabrics were produced. The contents are shown in Table 1 below together with Example 1.

Comparison rows 1 to 10 [31 In J1, one or two types of lubricant were used, and other conditions were the same, and all the original fabrics were trial-produced.

The contents are shown in Table 2 below.

(Margin below) After punching out the original fabric obtained in the above implementation row and comparison row into a disk shape and polishing the surface, it was inserted into a case to make a floppy disk.This disk was double-sided with a head pressure increased to 47.5g. The disk was loaded into the drive and accelerated durability tests were conducted at 6°C, 40% R, H, and 40'C, 80% R,H.The above disk was also loaded into the double-sided drive at 26°C, 60% R, H8. Then, 10 cycles of running for 30 minutes and stopping for 1 minute were repeated, and the rate of change was calculated from the starting torque measurements before and after the test.In addition, the presence or absence of missing pulses and extra pulses was compared to examine the quality of the trunk. Table 3 summarizes the results.

(Leaving space below) As is clear from the results in Table 3, under the lubricant formulation conditions shown in the practical column, acceleration durability, starting torque increase rate, and track quality are good under low temperature, low humidity and high temperature, high humidity conditions. It can be seen that a disc with a high quality can be obtained.

On the other hand, as shown in comparison ff1J, when only one or two of the three aliphatic-basic acid esters, glycerin triesters, and phosphoric acid trialkyl esters are used, all of the above characteristics can be simultaneously satisfied. I know it's difficult to do.

Effects of the Invention As described above, according to the present invention, a magnetic coating film containing at least three types of lubricants, an aliphatic-basic acid ester, a glycerin triester, and a phosphoric acid trialkyl ester, is supported. It is possible to obtain a magnetic recording medium that has high durability, running stability, and reliability under a wide range of environmental conditions.

Claims (1)

[Claims] As a lubricant, at least three of the following are an aliphatic-basic acid ester, a glycerin triester, and a phosphoric acid trialkyl ester.
1. A magnetic recording medium comprising: a magnetic coating film containing a magnetic material formed on a support.