JPS5883331A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve compatibility with a binder, to enhance lubricity and abrasion resistacnce, and to obtain a magnetic recording medium superior in running stability and durability, by incorporating a specified modified org. silicone compd. into a magnetic layer and allowing said compd. to ooze out of said layer properly. CONSTITUTION:A modified org. silicone compd. is represented by the formula in which R1, R2 are CH3 or -R3OSO3M; R3 is 1-26C hydrocarbon, such as phenylene, CnH2n, CnH2n-2; M is H, monovalent metal, or NH4; n1, n2 are as fllows: 0<=n1<1,000, 1<=n2<=500, n1+n2<=1,000. A magnetic paint is obtained by mixing said compd. with a binder resin, solvent, magnetic powder, etc.. Said compd. is added in 0.1-10wt% of the magnetic powder. A magnetic recording medium is obtained by coating a base of polyester film with this coating, drying, and its surface is treated, and it has small frication coefft. and enhanced running stability and weather resistance.

Description

Detailed Description of the Invention The present invention relates to a magnetic recording medium, and its main purpose is to improve the lubricity and abrasion resistance of a magnetic layer, and to provide a magnetic recording medium with excellent running stability and durability. It's about doing.

In general, 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, do not come into contact with magnetic heads, guide members, etc. The magnetic layer must have a low coefficient of friction and excellent running stability, and since it comes into intense sliding contact with the magnetic head during recording and playback, the magnetic layer suffers little wear and is highly durable. This is required.

For this reason, lubricants such as silicone oil have traditionally been used as a way to improve the lubricity and wear resistance of the magnetic layer.
It has been proposed to incorporate organic silicone compounds into the magnetic layer9, and it has also been proposed that organic silicone compounds modified with fatty acids represented by the following general formula (1) or (II) are mixed into the magnetic layer. .

(However, in the formula, R4 and R2 represent a saturated or unsaturated hydrocarbon group having 7 to 21 carbon atoms, and an integer of 0 to 50.

) OCR5 (However, in the formula, R5, R2 and R5 represent a saturated or unsaturated hydrocarbon group having 7 to 21 carbon atoms, m an integer of 1 to 100, n tri O an integer of 250, m + n
≦300, m≧n/5. ) However, although silicone oil has excellent lubricity, it has poor compatibility with the binder, which makes the magnetic layer inhomogeneous and tends to leak excessively onto the surface of the magnetic layer with pinholes. The fatty acid-modified organosilicone compounds represented by (I) and (1) have fatty acid residues with excellent affinity with binders in both terminals and in the main chain, so they are compatible with binders. Although the lubricity and wear resistance of the magnetic layer are improved, the lubricity and wear resistance of the magnetic layer are improved, but the results are still not fully satisfactory. (1) The inventors have conducted various studies in view of the above circumstances. As a result, the general formula (wherein R1 and R2 are -CH,t or -R,0
50, M % R, is a hydrocarbon group having 1 to 26 carbon atoms, M
#1 represents a valent metal element or -NH4, n, and n2 0≦n, < is 000.1 chi nx
≦500, n+n ≦1000 integer [f that is □ in number,
1) When the modified organosilicone compound shown in 2 is contained in the magnetic layer, the compatibility with the binder becomes moderately good, and the magnetic layer does not exude excessively or form pinholes on the surface of the magnetic layer. The present inventors have discovered that the lubricity and wear resistance of the material can be sufficiently improved, leading to the present invention.

The modified organosilicone compound used in this invention is in the main chain or in the main chain and at both ends of the main chain as shown in the above general formula.

-R050M (R, /fi hydrocarbon group, Mkey 1 or 5 monovalent metal element or -NH4) has a highly polar modified group with excellent affinity with the binder, so it is a binder. These highly polar modified groups also have good lubricity. In addition to the main chain consisting of an organic silicone compound with excellent lubricity, these modified groups also exhibit an excellent lubricating effect, further improving the lubricity and abrasion resistance of the magnetic layer. Especially in the main chain. If these modified groups are also present at both ends of the main chain, the effect will be significant, and therefore, according to the present invention, the lubricant will not excessively ooze out onto the surface of the magnetic layer or cause pinholes. The lubricity and abrasion resistance of the magnetic layer are sufficiently improved without causing paper-cutting, and a magnetic recording medium with excellent running stability and durability can be obtained.

In the organic silicone compound of the present invention represented by the above general formula, -130'30. R of the modifying group represented by M is an aromatic compound such as -(]←, -(CH2)m=(DH), and is a saturated or unsaturated hydrocarbon group represented by the general formula CnH2n+CnH2n-+, Carbon number is 1-2
It is preferable that the number of carbon atoms is within the range of 6. If the number of carbon atoms is less than 1, the wear resistance will not be sufficiently improved, and if it exceeds 26, the lubricity may be deteriorated. Furthermore, since the polarity of the modified group greatly affects the lubricating effect, the modified group M must be a monovalent metal element such as -H spanning -Nas- or a strongly polar one such as -NH. -0 Specific examples of such modifying groups include -C2I (4050, Na s -C2H40SO,
K s-C7H,O20,H% -C2H4050,
NH,%-C51(1゜O20,Na%-C5H
,o0503H%-C5H,0050,NHj,-C2
6H52050, Na 1-C26HS2050. H%
-C26H52050,NH,, -C2H20SO
, NaN-C26H5o0505Na, and the like.

R and R2 are methyl groups or the same modified groups as mentioned above, and if R4 and R2 are the same modified groups as mentioned above, the compatibility with the binder will be even better and moderate, and the lubrication of the magnetic layer will be improved. The properties and wear resistance are also further improved. Note that R4 and R7 may be the same or different.

In addition, the degree of polymerization, that is, n in the above general formula, and n2 digit 0≦
n, <1000.1≦n2≦500, n, + n2≦
Preferably an integer of 1000, n, and n2
If it is too large, it will dissolve in organic solvents and become difficult to form into a paint, and the lubricity and wear resistance will not be sufficiently improved.

Such modified organic silicone compounds of the present invention may be used alone or in combination of two or more, and the amount of the modified organic silicone compound of the present invention may be 0.1% by weight or more relative to the magnetic powder in the magnetic layer. The effect is exhibited when it is contained in the liquid, and the effect becomes more pronounced as the content increases. However, if the content exceeds 10% by weight based on the magnetic powder, it may excessively ooze out onto the surface of the magnetic layer, contaminating the magnetic head, and reducing the output. It is preferable to incorporate the modified organic silicone compound of the present invention into the magnetic layer within the range of the beak. In order to incorporate the modified organic silicone compound of the present invention into the magnetic layer, it is mixed and dispersed with magnetic powder, a binder, an organic solvent, etc. to form a magnetic layer. This can be done by preparing a coating material, applying the magnetic coating material onto a substrate such as a polyester film, and drying it. The solution may be applied or sprayed onto a previously formed magnetic layer, or conversely, the magnetic layer may be immersed in the solution.

The magnetic powder used in particular is, for example, r -Fe2
0. Powder, Fe, 04 powder, CO-containing 'r-Fe20° powder, Co-containing Fe, 0. Powder, CrO2 powder and other F
Various conventionally known magnetic powders such as e powder, Co powder, and Fe-Ni powder are widely included. Also, as a binder,
Vinyl chloride-vinyl acetate copolymers, hnylidene chloride resins, acrylonitrile-butadiene copolymers, vinyl butyral resins, polyurethane resins, cellulose resins, isocyanate compounds, etc., which are commonly used as binders for magnetic powders. Any of these may be used, and among them, vinyl chloride-vinyl acetate copolymers, cellulose resins, polyurethane resins, and the like are preferably used.

The organic solvent is not particularly limited, and includes solvents suitable for dissolving the modified organic silicone compound and binder of the present invention, such as ketone solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone, ethyl acetate, and acetic acid. Ester solvents such as butyl, aromatic hydrocarbons such as benzene, toluene, and xylene, alcohol solvents such as isopropyl alcohol, acid amide solvents such as dimethylformamide, and ether solvents such as tetrahydrofuran and dioxane are used alone. or a mixture of two or more.

In addition, various additives commonly used in magnetic paints,
For example, a dispersant, an abrasive, an antistatic agent, etc. may be optionally added and used. Next, an embodiment of the present invention will be described.

Example 1 A modified organosilicone compound having the structural formula was used.
1 vinyl-vinyl acetate-vinyl alcohol copolymer) Pandex T-5250 (manufactured by Dainippon 8 parts by weight Ink Co., Ltd., urethane elastomer) Coronae) L (manufactured by Nippon Polyurethane 21 Gyosha, trifunctional low molecular weight isocyanate compound) Cyclohexanone A magnetic coating material was prepared by mixing and dispersing a mixture consisting of 50 parts of methyl ethyl ketone and 11 parts of jF-modified organic silicone compound in a ball mill for 70 hours.

This magnetic paint was applied onto a polyester film having a thickness of 11 .mu.m to a dry thickness of 5 .mu.m, dried, surface treated, and then cut into 3.8 mm widths to produce magnetic tapes.

Example 2 In the composition of the magnetic paint according to Example 1, a modified organic silicone compound represented by the following structural formula was used in place of the modified organic silicone compound having the structural formula shown in Example 1 in the same amount. A magnetic tape was made in the same manner as in Example 1.

CH.

Comparative Example 1 In the composition of the magnetic paint in Example 1, the same amount of dimethylpolysiloxane type silicone oil represented by the following structural formula 1 was used in place of the modified organic silicone compound having the structural formula shown in Example 1. A magnetic tape was made in the same manner as in Example 1.

Comparative Example 2 In the composition of the magnetic paint in Example 1, the same amount of the modified organic silicone compound represented by the structural formula below was used in place of the modified organic silicone compound having the structural formula shown in Example 1. A magnetic tape was made in the same manner as in Example 1.

The durability test was conducted on the magnetic tape obtained in each example and each comparative example, and the friction coefficient was measured in the O durability test.
Under the conditions of 5°C and 80 faRH, each magnetic tape was played by running at a head load of 10 and a running speed of 4.8C111/see, and the number of runs until the output decreased by 3 dB from the initial output was measured. , Friction Coefficient Co., Ltd. A magnetic tape was run under the same conditions as in the durability test described above, and the friction coefficient with the magnetic head after running 200 times was measured.

The table below shows the results.

As is clear from the table above, the magnetic tapes obtained by the present invention (Examples 1 and 2) are different from the conventional magnetic tapes (Comparative Examples 1 and 2).
and 2), both have a smaller coefficient of friction and better durability, which shows that the magnetic recording medium obtained by the present invention has excellent running stability and durability.

Claims (1)

[Claims] 1. General formula (wherein R4 and R2 -CH5'4 Shitake R3
0S Os M % R5 hydrocarbon group having 1 to 26 carbon atoms, M represents -H or a monovalent metal element or -NH, n and n2 are O≦n, <1000.1≦n
It is an integer of 2≦500 and n1+n2≦1000. ) A magnetic recording medium having a magnetic layer containing an organic silicone compound represented by