JPS5898838A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance traveling stability and durability, by adding a specified org. silicone compd. into a magnetic layer. CONSTITUTION:A magnetic layer consisting mainly of a magnetic powder and a binder contains an org. silicone compd. represented b8 the formula (R1, R2 are -CH3 or -R3CONH2, R3 is 1-26C hydrocarbon group, and n1, n2 are each an integer shown as follows: 0<=n1<1,000, 1<=n2<500, n1+n2<=1,000) having polar groups represented by -R3CONH2 superior in compatibility with the binder, on the main chain or on the main chain and at both its ends.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and an object thereof is to improve the lubricity and wear resistance of a magnetic layer, and to provide a magnetic recording medium that has excellent running stability and durability. be.

In general, magnetic recording media such as magnetic tapes are made by coating a magnetic material such as a polyester film with a magnetic paint consisting of magnetic powder, a binder, a cotton solvent, and other necessary components. The magnetic layer must have a small coefficient of friction and excellent running stability because it travels while making contact with guide members, etc.; It is required to have a low bond and excellent durability.

For this reason, as a measure to improve the lubricity of the magnetic layer and its susceptibility, lubricants such as silicate and corn oil have been impregnated into the magnetic layer. It has been proposed that a fatty-modified/ζ metallurgical silicone compound represented by formula (1) or (II) is mixed into the magnetic layer.

((!(, L, where R and R2 are l prime numbers 7 to 21
Saturated or unsaturated hydrocarbons (, n = 0 to 50 4)
(Shows Iwo/l.) 11 0 CH,.

(11i, in the formula R1, ■?, and ■ra01 carbon number 7
~21 saturated or unsaturated hydrocarbon groups, m is 1 to 10
An integer of 0, n represents an integer of 0 to 250, m + n≦3
00, m≧n/5. )Although silicone oil has good lubricity and wears, it has poor compatibility with the binder, which makes the magnetic layer inhomogeneous and causes pinholes and the magnetic surface K1l1. ', l
The silicone compound has fatty acid-modified silicone compounds represented by the general formulas (1) and (11) that have an affinity for the binder at both ends or in the main chain. Because it has fatty acid residues with excellent properties, it improves compatibility with the binder and exhibits a lubricating effect, improving the lubricity and abrasion resistance of the magnetic layer, but it is not completely satisfactory without using it. do not have.

The inventors took this into account and worked diligently to carry out inspections, and as a result, the general formula (however, in the formula R and R2 ke -CH, or -R, CO
NH2, R5 represents a hydrocarbon group having 1 to 26 carbon atoms,
n, and R2 are 0≦n+<1000.1≦11
2≦500, n is an integer of +12≦1000. ) When the modified organosilicone compound shown in ( ) is contained in the magnetic layer, the compatibility with the binder becomes moderately good, and the lubrication of the magnetic layer is achieved without excessive exudation or formation of pinholes on the surface of the magnetic layer. We have found that the properties and abrasion resistance can be sufficiently improved, and have come up with this invention.

The modified organosilicone compound used in this invention has a polarity represented by -R5C0NH2 (R, hydrocarbon group) in the main chain or in the main chain and at both ends of the main chain, as shown in the above general formula. Parents with strong binders,
Since it has a compatible VCf11-netamodified group, it is well compatible with the binder, and accordingly, it oozes out to the surface of the magnetic layer appropriately, and does not excessively ooze out or cause pinholes on the surface of the magnetic layer. In addition, these highly polar modified groups have good lubricity, and together with the main chain consisting of an organic silicone compound with excellent lubricity, these modified groups also exert an excellent lubricating effect. lubricity and wear resistance are further improved. In particular, the effect is remarkable when these modified groups are present not only in the main chain but also at both ends of the main chain, and therefore, the present invention prevents lubricants from exuding excessively onto the surface of the magnetic layer. The lubricity and abrasion resistance of the magnetic layer are sufficiently improved without causing pinholes or pinholes, and a magnetic recording medium with excellent running stability and durability can be obtained. In the organic uricone compound of the present invention, R3 of the modifying group represented by -R,CONH2
is an aromatic compound such as -()-1-(c■,2) []- or the general formula CnH2n or CnH2n
It is a saturated or unsaturated hydrocarbon group represented by -2, and the number of carbon atoms is preferably within the range of 1 to 26. If the number of carbon atoms is less than 1, the improvement in wear resistance will not be sufficient, and if it exceeds 26, it will lubricate. There is a risk that the performance may actually decrease.

Specific examples of such modifying groups include -C2
H4CONH2, -C5H1oCONH2, C1oH2
oCON H2, 'C2a H52CON H2, -C
21-12CON H2 and the like.

R7 and R2 are a methyl group or the same modified group as in the previous d1-1, and when R4 and R2 are the same modified groups as in the previous d1-1, the compatibility with the binder is even better and suitable lI'. This further improves the lubricity and RFI wear resistance of the magnetic layer.6 Note that only R1 and R2 may be the same or different.

The degree of polymerization, that is, nl and n2 in the above general formula, is 0≦
J < 1000, ■≦n2≦500, n, +n2≦1
Preferably, they are integers of 000. If n and n2 are too large, they will dissolve in organic solvents and turn into paint or an inner shell, and the lubricity and abrasion resistance will not be sufficiently improved.

Such modified organic silicone compounds of the present invention may be used alone or in a mixture of two or more, and the amount of the modified organic silicone compound of the present invention may be 0.1@tft% based on the magnetic powder.
When it is contained in the magnetic layer, its effectiveness is exhibited, and as the content increases, the effect becomes more pronounced. However, if the content exceeds 10% based on the magnetic powder, it may leak excessively onto the surface of the magnetic layer, contaminating the magnetic head and reducing the output. Should it be included in the magnetic layer? preferable.

In order to incorporate the modified organic silicone compound of the present invention into a magnetic layer, a magnetic paint is prepared by mixing and dispersing the modified organic silicone compound with a magnetic powder, a powder, an organic solvent, etc.1. This can be done by coating and drying the modified organic silicone compound of the present invention in an appropriate solvent and coating the solution obtained by dissolving it on the magnetic layer that has been shaded in advance. The magnetic layer may be formed by spraying or by directly dipping the magnetic layer into the above solution.

As the magnetic powder used here, for example, r-Fe
20s powder, Fes 04 powder, Co containing r-F
e205 powder wood, Co-containing Fe, 0. Powder, (-r 02
In addition to powder, various conventionally known magnetic powders such as Fe powder, Co powder, and Fe-Ni powder are widely included. In addition, binders include base vinyl-vinyl acetate copolymer, vinylidene chloride resin, acrylonitrile-butadiene thread copolymer, vinyl butyral resin, polyurethane thread resin,
All materials that are normally used as binders for magnetic powder, such as fiber resin and isocyanate compounds, are used, and among them, vinyl chloride-vinyl acetate copolymers, fiber resin, polyurethane resins, etc. are preferred. 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, An ethyl, and acetic acid. Ester solvents such as butyl, aromatic hydrohydrogen solvents such as Hensen, toluene, and xylene, alcohol solvents such as isopropyl alcohol, acid amide thread solvents such as dimethylformamide, and ether solvents such as tetrahydrofuran and dioxane are used alone. It can be used in combination or in combination.

In addition, various additives 111 commonly used in magnetic paints
] For example, dispersants, abrasives, antistatic agents, etc. may be optionally added.

Next, the practical aspects of this invention will be explained.

Example 1 Using a modified organosilicone compound represented by the structural formula, Copolymer) Pandex' -5250 (Dai 11 8 Manufactured by Hon Ink Co., Ltd., Urethane Elas) Coronate L (FI polyurethane 2 Koushiba 7 (legs, trifunctional 1/1 low molecular weight) i > Isocyanate I/Compound) Cyclohexanone 50 t4<it
81 (Mezal ethyl ketone 50
A magnetic paint was prepared by self-dispersing a mixture consisting of a modified organic silicone compound 1 in a ball mill for 7 hours.
ψ drying + r7 or 5 on 1μ polyester film -1-
The magnetic tape was coated and dried to give a thickness of μ, and the surface was filled with 1 iL: 3.8 mm rl] K was cut to make a magnetic tape. A magnetic tape was prepared using the same amount as in sister example 1 (F) except that the same amount of a modified organic silicone compound represented by the structural formula of Monarchy was used in place of the modified organic silicone compound having the structural formula shown in [Example].

CH.

Comparative Example 1 4 (The composition of the magnetic paint in Example ■ is true!
ii+i Example IvC Instead of the modified organic silicone compound having the structural formula shown in 1;
1 Jul using the same amount of Shirogisan type silicone oil
A magnetic tape was made in the same manner as Example 1.

Comparative Example 2 A modified silicone compound having the structural formula shown in Practical Example 1 and having a composition with compatibility #5 in Practical Example 1.
Instead, a silicone compound expressed by the structural formula of 1: 1: 1: 1: 1: 1: 1: v' , and made magnetic tape.

11 1 0 CH The durability of the magnetic tapes obtained in each Example and each Comparative Example was tested and the coefficient of friction was measured.

Durability tests were conducted under conditions of 35°C, 180% RH, head load of 10 lbs., and running speed of 4.13 cm/
Run at sec to generate Pf, output or 3d from initial output
The number of runs until B decreases is -(1). Measure the coefficient of friction between the magnetic head and the magnetic head after walking 200 times.

The table below shows the results.

As is clear from the table, the magnetic tapes obtained by the present invention (Examples 1 and 2) have lower coefficients of friction and are more durable than conventional magnetic tapes (Comparative Examples 1 and 2). This indicates that the magnetic recording medium obtained by the present invention has excellent running stability and durability.

Claims (1)

[Claims] 1. General formula (wherein R and R2 are -CH, or -R, co
NH2, R, represents a hydrocarbon group having 1 to 26 carbon atoms,
nl and n2 ke O≦n, <1000.1≦n2≦50
0, J112≦1000. ) A magnetic recording medium having a magnetic layer containing an organic silicone compound represented by