JPS60193133A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve remarkably durability of a magnetic layer by providing a magnetic layer in which a compd. having the specific constitutional formula is incorporated alone or in combination with higher fatty acid ester. CONSTITUTION:The compd. expressed by the formula can be added alone as a lubricating agent into a magnetic layer and can be also added in combination with ordinary fatty acid ester composed of fatty acid and alcohol. The much better effect is often obtd. with respect to the durability of a magnetic layer in this case as compared to the case in which said compd. and fatty acid ester are used respectively independently. The amt. at which the compd. expressed by the formula is added or the total amt. in the case of using said compd. in combination with the fatty acid ester is preferably 1-8wt%. If the amt. is too small, the effect of improving the durability is smaller and if the amt. is too large, the additives such as the lubrication agent or the like stick to calender rolls in the calendering stage for improving the surface smoothness of the coated magnetic film or the surface of the coated magnetic film has unevenness like stains.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium that can be used for magnetic tapes, floppy disks, and the like.

Conventional Structures and Problems Many magnetic recording media are made by coating a magnetic paint on a support such as a polyester film. Since magnetic recording media are used in sliding contact with magnetic heads, they have a high degree of wear resistance. For this purpose, hard non-magnetic fine particles are added to the magnetic coating film as a lubricant and coating strengthening agent, and play an important role.

Conventionally, fatty acid esters, liquid hydrocarbons, silicone oils, fluorine oils, etc. have been used as lubricants. However, many of these have poor affinity for magnetic coatings and the binders used in them, so they cannot be used for magnetic layers. There was a tendency for too much seepage to the surface. For this reason, it is often lost due to sliding contact with magnetic heads, liners, etc., and it has been difficult to maintain good durability and wear resistance over a long period of time.

OBJECTS OF THE INVENTION An object of the present invention is to provide a highly durable magnetic recording medium.

Structure of the Invention An uninvented magnetic recording medium is characterized by having a magnetic layer containing a compound having a structural formula represented by the following formula 1 alone or in combination with a higher fatty acid ester. This makes it possible to achieve excellent durability.

R1COO(C2H40)ml(CH2)no(R1C
00(C2H40)・・・・・・・・・(1) Formula The compound represented by the formula 1 used in the present invention has a type similar to a fatty acid ester made of a dihydric alcohol and a monobasic acid.0However, It differs in that it has a gated ethylene chain in its molecule, which makes it uniquely polar and has a wide range of adsorption and solubility for other substances.

Note that if the length of the ethylene oxide chain or methylene chain in formula 1 is too long, the above activity will decrease, so m,
, m2=1-5, 11=2-10 are preferred.

The compound represented by formula 1 has the above-mentioned characteristics, and because it has a moderate affinity for the composition that makes up the magnetic layer, it exudes to the surface of the magnetic layer in an appropriate amount and maintains stable lubricity over a long period of time. , the durability of the magnetic layer can be significantly improved.

The compound represented by formula 1 can be added alone to the magnetic layer as a lubricant, but it can also be used in combination with a normal fatty acid ester made of fatty acid and alcohol. In this case, a greater effect on the durability of the magnetic layer is often obtained than when each is used alone. The fatty acid ester used in combination is one made of a monobasic acid with 8 to 18 carbon atoms and an alcohol with 1 to 18 carbon atoms, or one with 3 carbon atoms.
Esters of the type with ~10 dibasic acids and alcohols with 1 to 18 carbon atoms are preferred, examples being lauryl laurate, impropyl myristate, octyl palmitate, butyl stearate, oleyl oleate, dioleyl maleate, Examples include dioleyl adipate and dioctyl sebacate. Many dibasic acid esters have high oil film strength and are particularly effective in increasing the durability of magnetic coatings.

The amount of the compound represented by Formula 1, or the total amount when a fatty acid ester is used in combination, is preferably from 1 to 8M. If the amount added is too small, there will be little effect on improving durability, and if the amount added is too large, additives such as lubricants will adhere to the calender roll during the calendering process to improve the surface smoothness of the magnetic coating. This is because stain-like unevenness may occur on the surface of the magnetic coating film.

Description of Examples Example 1 Acicular γ iron oxide (major axis 0.4 μm, axial ratio 8) 620 parts (parts by weight, same hereinafter), α alumina powder ('Fj, diameter approximately 0.
5 μm) 15 parts, carbon black (C8x150A-
2. Manufactured by Cabot) 40 parts, polyurethane (N-23
04, manufactured by Nippon Polyurethane Co., Ltd.) 120 parts.

Salt, vinyl, vinegar, polyvinyl alcohol copolymer (VAGH)
, manufactured by tJCC) 120 parts, stearic acid 8 parts, lecithin (made from soybean) 6 parts, curing agent (Coronate L2 manufactured by Nippon Polyurethane Co., Ltd.) 46 parts, MEK 1600 parts, toluene 80 parts
1 part to a magnetic paint consisting of 0 parts and 600 parts of cyclohexanone.
In the formula R1-R2=C11H23, rr11=29
m2=3. 25 parts of the compound represented by n=6 was added, mixed well, and then coated on a 76 μm thick polyester film.

It was dried, calendered, and heated to harden, punched out into a disk shape with an outer diameter of 72mm, and the surface polished to obtain a test sample.

The surface gloss of the thus prepared sample (Nippon Denshoku Kogyo gloss meter) was 132.

Next, the head pressure was increased to the normal 300r (48g) ic.
, pm driver and performed an accelerated durability test, the initial reproduction output value was 3. αW is 1. It took 416 hours for the playback output to drop to 70% of the initial value. The results are shown in the table below.0 Margin Example 2 In Example 1, the results of tests were conducted by changing only the type of compound of formula 1 are shown in the table.

Example 3 In Example 1, the amount of the compound of Formula 1 added was 16 parts, and the results were also shown in the table when 10 parts of oleyl oleate was added.

Example 4 In Example 3, the results when other fatty acid esters were used instead of oleyl oleate are shown in the table.

Comparative Example 1 The results obtained when the compound represented by Formula 1 was not added in Example 1 are also shown in the table.

Comparative Example 2 The results obtained when oleyl oleate was used in place of the compound represented by Formula 1 in Example 1 are also shown in the table.

Effects of the Invention As is clear from the above Examples and Comparative Examples, when the compound represented by formula 1 as in the present invention is added to a magnetic paint alone or in combination with a fatty acid ester, the compound represented by formula 1 is obtained. A magnetic recording medium with superior durability can be obtained compared to the case where no compound is added. This is because the compound of Formula 1 has a moderate affinity for the magnetic layer, so it oozes out to the surface of the magnetic layer, maintains stable lubricity over a long period of time, and significantly increases the durability of the magnetic layer. It is.

Claims (1)

[Claims] (1) The following structural formula: R1COO(C2H40)ml(CH2)no(R1C
A magnetic recording medium characterized by having a magnetic layer containing a ゛ compound having 00 (C2H40). (→ Structural formula below: RlCoO(C2H40)ml(CH2)no(C2H
40) A magnetic recording medium characterized by having a magnetic layer containing a compound having m20oR2 and a higher fatty acid ester.