JPS6242339B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to magnetic recording media. Magnetic recording media are generally made by coating a substrate such as a polyester film with a magnetic paint made from magnetic powder and a binder using various methods. In addition, in order to improve the dispersibility of the magnetic powder in the magnetic paint and improve the orientation of the magnetic properties,
Surfactants are added into magnetic paints. The inventors investigated this compound and found that

【formula】

[expression] and

[Formula] (where R ₁ is an alkyl group or alkyl phenyl group having 8 to 20 carbon atoms, and n is 2 to 10) If one or more of the compounds is used, the dispersibility will be good. It has been found that the magnetic properties are excellent in orientation. As a result of further investigation, it was found that the orientation is particularly good when R ₁ is an alkyl group or alkyl phenyl group having 8 to 20 carbon atoms, and n is 2 to 10 carbon atoms, but when the amount added is increased, bleed occurs. It was found that there were adverse effects such as phenomena such as blocking and softening of the coating film. As a result of intensive research into how to obtain a durable coating film without impairing dispersibility and orientation, we were able to solve the problem by using a certain type of compound in combination. That is,

[expression] and

[Formula] (where R ₂ is an alkyl group having 12 to 20 carbon atoms or an alkyl phenyl group) By combining one or two of the compounds represented by the above organic phosphorus compound, the dispersion and orientation can be improved. Of course, it was found that a durable coating film could be obtained. Examples are shown below. Example 1 Magnetic powder 100 parts by weight Vinyl chloride vinyl acetate copolymer 10.2 Polyurethane resin 8.2 (A)R ₁ is nonylphenyl group n is 9 3.5 (B)R ₂ is oleyl group 1.5 Example 2 Magnetic powder 100 Parts by weight Vinyl chloride Vinyl acetate copolymer 10.2 〃 Acrylic rubber 8.2 〃 (A)R ₁ is a tridecyl group n is 5 3.5 〃 (B)R ₂ is a palmityl group 1.5 〃 Example 3 Magnetic powder 100 parts by weight Vinyl chloride Vinyl acetate Copolymer 10.2 〃 Polyurethane resin 8.2 〃 (A)R ₁ is a nonylphenyl group n is 4 3.5 〃 (B)R ₂ is a stearyl group 1.5 〃 Comparative example magnetic powder 100 Vinyl chloride vinyl acetate copolymer 10.2 Polyurethane resin 8.2 (A )R ₁ is a nonylphenyl group n is 9 5.0 or more Magnetic recording media were prepared using these compositions in Examples 1 to 3 and Comparative Examples by a known method. FIG. 1 shows the change in orientation when the number of carbon atoms in the organic phosphorus compound was changed with n constant at 9 in the example. From this, it can be seen that a carbon number between 8 and 20 is favorable. FIG. 2 shows the change in orientation when n is changed with the number of carbon atoms in the organic phosphorus compound being constant at 9, and it can be seen from this that n is good when n is between 2 and 10. Figure 3 shows the optimum amount of surfactant added (B). According to this, (A) and (B)
It is found that the mixing ratio of the compound is between 5 and 1, and from Figure 4, a coating film that does not bleed or block, has dispersibility, does not inhibit orientation, and is durable is based on 100 parts by weight of magnetic powder. It is found that the amount is 2.0 to 6.0 parts by weight. Table 1 shows the squareness ratio and wear amount (100 hours, relative speed) for each of the above examples and comparative examples.
4.7m/sec). As is clear from Table 1, according to the present invention, it was possible to significantly improve the amount of wear as a magnetic recording medium without impairing the squareness ratio.

[Table] In the examples above, in the above general formula,
Examples of nonylphenyl group and tridecyl group as R ₁ , examples of 4, 5, and 9 as the value of n, and examples of oleyl group, palmityl group, and stearyl group as R ₂ are shown, but other compounds in the present invention shows the same effect as these.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams showing the optimal range of the organic phosphorus compound used in the present invention, and FIG. 3 is a diagram showing the effect of the blending ratio of the organic phosphorus compound and the organic boron compound, and , FIG. 4 is a diagram showing the effect of the amount of the dispersant added according to the present invention.

Claims (1)

[Claims] 1 [Formula] [Formula] and one or more of the compounds represented by [Formula] and [Formula] and A magnetic recording material containing one or two of the compounds represented by: However, R ₁ is an alkyl group or an alkyl phenyl group having 8 to 20 carbon atoms, R ₂ is an alkyl group or an alkyl phenyl group having 12 to 20 carbon atoms, and n is 2 to 10.