JPS5883333A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium good in compatibility with a binder resin, enhanced in lubricity and abrasion resistance of magnetic layer, and superior in running stability and durability, by adding a specified modified org. silicone compd. to the magnetic layer. CONSTITUTION:An org. silicone compd. is represented by the formula in which R1, R2 are CH3 or -R3COOM; R3 is 1-26C hydrocarbon, such as phenylene, CnH2n, or C2H2n-2; M is monovalent metallic element or NH4; n1, n2 are expressed as follows: 0<=n1<1,000, 1<=n2<=500, n1+n1<=1,000. A magnetic layer contg. said compd. in 0.1-10wt% of a magnetic powder is formed on a supporting film. A magnetic layer may be formed by adding said compd. to a magnetic coating, or coating a preformed magnetic layer with a soln. dissolved said compd., thus permitting lubricity and abrasion resistance to be enhanced.

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.

-4. Magnetic recording media such as magnetic tapes, which are made by applying magnetic paint consisting of magnetic powder, binder, organic solvent, and other necessary components, on a substrate such as a polyester film 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 magnetic heads during recording and playback, the magnetic layer has little wear and is highly durable. This is required.

Therefore, as a measure to improve the lubricity and wear resistance of the magnetic layer, it has been conventionally carried out to incorporate a lubricant such as silicone oil into the magnetic layer. It has been proposed that an organosilicone compound modified with a fatty acid represented by (II) is mixed into the magnetic layer. Hydrogen group, n is 0~
Indicates an integer of 5o. ) (However, in the formula, R,, R2 and R3Fi have 7 to 21 carbon atoms.
saturated or unsaturated hydrocarbon group, mFi an integer of 1 to 100, nFiO an integer of 250, m+n≦300
, m≧n15. ) However, although silicone oil has excellent lubricity, it has poor compatibility with the binder, which makes the magnetic layer inhomogeneous, causing pinholes, and tends to leak excessively onto the surface of the magnetic layer. The fatty acid-modified organosilicone compound represented by (1) and (1) has fatty acid residues with excellent affinity with the binder at both ends or both ends and in the main chain, so the compatibility with the binder is improved. Although the lubrication effect is exhibited and the lubricity and wear resistance of the magnetic layer are improved, it is still not fully satisfactory.

The inventors conducted various studies in view of the above circumstances and found that the general formula (wherein R4 and R, Fl-CR2 or -R,
C00M, R, tj hydrocarbon group having 1 to 26 carbon atoms,
M represents a monovalent metal element or -NH, and n, monument and fi2 are 0≦n1 < 1000.1≦n2≦500
, n1+n, is an integer of ≦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. The present inventors have discovered that the properties and abrasion resistance can be sufficiently improved, leading to the present invention.

The modified organosilicone compound used in this invention has -R, C00M (R5F
i is a hydrocarbon group, M is a monovalent metal element or ' is -NH,)
Because it has a modified group with strong polarity and excellent affinity with the binder, it is compatible with the binder, so it oozes out to the surface of the magnetic layer moderately and does not ooze out excessively to the surface of the magnetic layer. It does not cause pinholes. 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 exhibit an excellent lubricating effect, which improves the lubricity of the magnetic layer. and wear resistance is 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. Therefore, according to the present invention, the lubricant excessively oozes out 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 silicone compounds, R of the modifying group represented by -R, C00M is an aromatic group such as -(]-1(CHt) <-.
It is a saturated or unsaturated hydrocarbon group bridged by an aromatic compound or general formula CnH2n or CnH2n-z, and the number of carbon atoms is preferably within the range of 1 to 26, and if the number of carbon atoms is less than 1, the resistance is If the abrasion resistance is not sufficiently improved and it exceeds 26, there is a risk that the lubricity may deteriorate on the contrary. In addition, since the polarity of the MIIi modification group of the above modification group greatly affects the lubricating effect, for example -
Nas K"lk any monovalent metal element or -NH,
It is preferable to use something with strong polarity, such as -. Specific examples of such modifying groups include -C2H, CO
ONa 1-C,H,COONa,.

-C5H,. C00Naz-C,. H2OC00Na
s -C,, H2OC00Nas-C2oH4oCOO
Na, -C26Hs2COONa, -C21(2C
OONa1-C,H,C00Nas-C5H8COO
Na, -C1゜H2OC00Nas-C,H2OC0
0Nas -C20H51ICOONa, -C26H,
C00Nas-C2H, -C6H, C00Naq -c
6H, COONa 1-C2)T, cooK, -c
5T(,.C00K% -C26T(52COOK N
C2H4COONH41C5H1゜C00N)I,,-
C, A) I52COONH, etc. If OR and R2 are a methyl group or the same modified group as above, and R1 and R2 are the same modified groups as above, the compatibility with the binder is even better. And a moderate one, Nasho,
The lubricity and wear resistance of the magnetic layer are also further improved. Note that R4 and R2 may be the same or different.

Further, the degree of polymerization, that is, n and n2 in the above general formula are 0≦
n1<1000.1≦n2≦500, n1+n2≦10
An integer of 00 is preferable. If n and n2 are too large, it becomes difficult to dissolve in organic solvents, making it difficult to form into a paint, and the paperability, lubricity and abrasion 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 have a magnetic property of 0.1 weight or more with respect to magnetic powder. The effect is exhibited when it is contained in the layer, and the effect becomes more pronounced as the content increases. However, if the content exceeds 10% by weight based on the impact powder, it may leak excessively onto the surface of the magnetic layer, contaminating the magnetic head, and reducing the output. heavy f&
% in the magnetic layer.

In order to incorporate the modified organic silicone compound of this invention into a magnetic layer, it is mixed and dispersed with magnetic powder, a binder, an organic solvent, etc. to prepare a magnetic paint, and this magnetic paint is applied onto a substrate such as a polyester film. Alternatively, the modified organosilicone compound of the present invention may be dissolved in a suitable solvent and the solution obtained by dissolution may be coated or sprayed on a previously formed magnetic layer, or vice versa. The magnetic field 1 may be immersed in the above solution.

The magnetic powder used in particular is, for example, γ-Fe2o.
3 powder, Fe3O4 powder, CO-containing r-Fe20. In addition to powder, Co-containing Fe, O, powder, and CrO2 powder, various conventionally known magnetic powders such as Fe powder, Co powder, and Fe-Ni powder are widely included. In addition, binders include ordinary basic powders such as vinyl chloride-vinyl acetate copolymers, vinylidene chloride resins, acrylonitrile-butadiene copolymers, vinyl butyral resins, urethane resins, cellulose resins, and isocyanate compounds. Any of those used as a binder can be used, and among them, vinyl chloride-vinyl acetate copolymers, cellulose resins, and polyurethane resins 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 hydrocarbon solvents 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. Gado can be used alone or in combination of two or more types.

In addition, various additives commonly used in magnetic paints,
For example, a dispersant, an abrasive, an antistatic agent, etc. may be optionally added.

Next, one embodiment of the present invention will be described.

Example 1 Using a modified organic silicone compound represented by the structural formula, Co-containing r-Fe2-0. Magnetic powder 804 parts by weight VAGH (manufactured by U, C, C, USA, vinyl salt 10-vinyl acetate-vinyl alcohol copolymer) Bandex T-5250 (8 parts by weight, manufactured by Dainippon Ink Co., Ltd., urethane elastomer) Coronate L (manufactured by Nippon Polyurethane 2,
A magnetic paint was prepared by mixing and dispersing a mixture consisting of 11 components (trifunctional low molecular weight isocyanate compound) cyclohexanone (50 liters), 1 methyl ethyl ketone (50 liters), and 11 modified organic silicone compounds (trifunctional low molecular weight isocyanate 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 in Example 1vc, Example 1
A magnetic tape was prepared in the same manner as in Example 1, except that the modified organic silicone compound represented by the following structural formula was used in the same amount instead of the modified organic silicone compound represented by the structural formula shown below.

H3 Comparative Example 1 In the composition of the magnetic paint in Example llIc, instead of the modified organic silicone compound having the structural formula shown in Example 1,
A Katsuki tape was made in the same manner as in Example 1 except that the same amount of dimethylpolysiloxane type silicone oil represented by the following structural formula was used. Comparative Example 2 The composition of the magnetic paint in Example 1 was different from that in Example 1. A magnetic tape was prepared in the same manner as in Example 1, except that the same amount of myristic acid-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 below.

The magnetic tapes obtained in each Example and each Comparative Example were tested for durability and measured for friction coefficient.

Durability test: Under the conditions of 35°C and 80 SRH, each magnetic tape was subjected to a head load of 10 g and a running speed of 4.8 units/see.
The friction coefficient was determined by running the magnetic tape under the same conditions as the durability test described above.
The coefficient of friction with the magnetic head after running 00 times was measured.

The table below shows the results.

As is clear from the table above, the magnetic tapes obtained according to the present invention (Examples 1 and 2) and the conventional magnetic tape (Comparative Example 1)
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 R1 and R2 are -CH, or -RC0
0M, R, represents a hydrocarbon group having carbons I11 to 26, M represents a monovalent metal element or -NH, and n. and n2 digits 0≦n, <1000.1≦n2≦500,
nl is an integer of +12≦1000. ) A magnetic recording medium having a magnetic layer containing an organic silicone compound represented by