JPS59172133A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the resistance of a magnetic layer to wear and heat by adding lead naphthenate or tin naphthenate to a magnetic coating contg. an isocyanate compd. and applying said coating on a base body thereby forming a magnetic layer. CONSTITUTION:A magnetic coating contg. either one kind selected from lead naphthenate or tin naphthenate, isocyanate compd. and magnetic powder is coated on the body. When the lead naphthenate or tin naphthenate are added into the magnetic coating contg. the isocyanate compd., the crosslinking reaction between the isocyanate compd. and a binder resin such as a vinyl chloride resin, polyester resin, polyurethane resin or the like having active hydrogen is accelerated these compd. and resin are quickly crosslinked like network, by which the strength of the magnetic layer is improved and the resistance to wear and heat is improved. The amount of the lead naphthenate and the tin naphthenate to be used is preferably in a range of 0.1-10wt% by the total weight of the binder component.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and an object thereof is to provide a magnetic recording medium with excellent durability and heat resistance.

In general, magnetic recording media, which are made by coating a magnetic paint consisting of magnetic powder, a binder component, an organic solvent, and other necessary components on a substrate such as a polyester film, come into violent sliding contact with magnetic heads, etc. during recording and playback. The magnetic layer is easily abraded, so a material with excellent durability and little abrasion is required.

In order to meet these demands, various improvements have been made to binder components. For example, a curing accelerator such as zinc naphthenate is added to a magnetic paint containing an isocyanate compound, and this curing accelerator is The wear resistance of the magnetic layer is improved by strengthening the strength of the magnetic layer.

However, by adding this zinc naphthenate to the magnetic paint, the crosslinking reaction between the isocyanate compound and other binder components containing active hydrogen is promoted and the strength of the magnetic layer is improved, but it is still not sufficient. , wear resistance and heat resistance are still not fully satisfactory.

The inventors conducted various studies in view of the current situation, and found that by adding lead naphthenate or tin naphthenate to a magnetic paint containing an isocyanate compound and coating it on a substrate to form a magnetic layer. Since the curing accelerating effect of lead naphthenate or tin naphthenate is superior to that of conventional zinc naphthenate, the crosslinking reaction of the isocyanate compound is rapidly promoted and the strength of the magnetic layer is sufficiently strengthened.
The inventors have discovered that the abrasion resistance and heat resistance of the magnetic layer can be sufficiently improved, leading to the present invention.

The lead naphthenate or tin naphthenate used in this invention has a much better effect of promoting the crosslinking reaction between the isocyanate compound and other binder components containing active hydrogen than the conventional zinc naphthenate, and therefore When this kind of lead naphthenate or tin naphthenate is added to a magnetic paint containing an isocyanate compound, the isocyanate compound and vinyl chloride resin, polyester resin, polyurethane resin, polyvinyl acecool resin, cellulose resin The crosslinking reaction with the binder resin containing active hydrogen is further promoted, and these are quickly crosslinked into a network, thereby strengthening the strength of the magnetic layer and improving its abrasion resistance and heat resistance. Furthermore, since these types of lead naphthenate and tin naphthenate have good compatibility with commonly used binder resins, they are well mixed into the magnetic coating material, and the above-mentioned crosslinking reaction promoting effect is sufficiently exerted. Such an effect is exhibited by adding 0.1% by weight or more of lead naphthenate or tin naphthenate to the total amount of binder components, and the effect becomes more pronounced as the amount added increases, but if the amount is more than 10% by weight. If this happens, there is a risk that they will bleed out onto the surface of the magnetic layer and deteriorate the electromagnetic conversion characteristics, so the amount of lead naphthenate and tin naphthenate used is 0.1 to 10% by weight based on the total amount of binder components.
It is preferable to keep it within the range of .

The isocyanate compound is not particularly limited as long as it is a compound having an isocyanate group; for example, 2. ,
Diisocyanate compounds such as i-tolylene diisocyanate, m-phenylene diisocyanate, 1,5-naphthalene diisocyanate, and trifunctional low molecular weight isocyanate compounds usually obtained by reacting 1 mol of triol with 3 mol of diisocyanate. If these isocyanate compounds are used in combination with other binder resins containing active hydrogen, they will crosslink and strengthen the magnetic layer. Alternatively, when tin naphthenate is used in combination, the crosslinking reaction is further promoted, thereby further strengthening the strength of the magnetic layer and further improving the abrasion resistance and heat resistance of the magnetic layer. Specific examples of trifunctional low molecular weight isocyanate compounds include, for example, Coronate L manufactured by Nippon Polyurethane Industries, Ltd., Takenate D102 manufactured by Takeda Pharmaceutical Company, Desmodur Shi1 manufactured by Bayer, and Crisbon NX manufactured by Dainippon Ink and Chemicals. .

As the binder resin used in combination with the isocyanate compound, those normally used in manufacturing magnetic recording media are suitably used, including vinyl chloride resin, cellulose resin, polyurethane resin, and polyvinyl acecool. Binder resins having active hydrogen, such as polyester-based resins and polyester-based resins, are preferably used.

Magnetic powders include γ2Fe2O3 powder, Fe3O4 powder, CO-containing r-Fe203 powder, CO-containing Fe3O4
powder, CrO2 powder, Fe powder, CO powder, Fe-
Various conventionally known magnetic powders such as metal powders such as Ni powder are widely used.

Further, as the organic solvent, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, toluene, ethyl acetate, tetrahydrofuran, dimethylformamide, etc. are used alone or in combination of two or more.

In addition, various additives commonly used in magnetic paints,
For example, dispersants, lubricants, abrasives, antistatic agents, and the like may be optionally added.

Next, embodiments of the present invention will be described.

Example I CO-containing r-Fe203 powder 80 parts by weight VA
G H (vinyl chloride 10 - vinyl acetate-vinyl alcohol copolymer manufactured by U, C, C, Co., Ltd.) Nof Desox T-5201 (large 8 urethane elastomer manufactured by Nippon Ink Co., Ltd.) Coronate L (Japan Polyurethane 2) trifunctional low molecular weight isocyanate compound) Lead naphthenate 1.0 Methyl isobutyl ketone 50 Toluene
50〃This composition was mixed and dispersed in a ball mill for 72 hours to prepare a magnetic paint.
It was applied onto a polyester base film having a coating thickness of 5 μm. Next, after calendering, the tape was cut into a predetermined width to make a magnetic tape.

Examples 2 to 4 Magnetic tapes were produced in the same manner as in Example 1 except that the amount of lead naphthenate used in the composition of the magnetic paint in Example 1 was changed as shown in Table 1 below.

Table 1 Example 5 Example 1 except that in the composition of the magnetic paint in Example 1, the same amount of naphthene oxide was used instead of lead naphthenate.
I made magnetic tape in the same way.

Comparative Example 1 A magnetic tape was prepared in the same manner as in Example 1 except that the same amount of zinc naphthenate was used in place of lead naphthenate in the composition of the magnetic paint in Example 1.

Regarding the magnetic tapes obtained in each example and comparative example,
Tested for heat resistance and abrasion resistance. The heat resistance test was performed by cutting the obtained magnetic tape into a length of 1.5 m, applying a load of 1 kg, wrapping it around a glass tube with a diameter of 361 cm, and heating it at 60°C.
After storing the tape in a constant temperature bath at 80% RH for 48 hours and leaving it at room temperature for 24 hours, the tape was unwound from the glass tube and the degree of adhesion between the tape layers was observed.
It was evaluated as (◎) if it was not seen, (○) if it was rarely seen, (△) if it was seen slightly, and (×) if it was rarely seen. .

In addition, the abrasion resistance test was conducted by loading each magnetic tape into a tape recorder and running it at a running speed of about 4.8 cm/sec for 600 minutes.
This was done by measuring the output fluctuation after running the vehicle twice.

Table 2 below shows the results.

As is clear from the upper table of Table 2, the magnetic tapes obtained in Examples 1 to 5 all had better heat resistance and smaller output fluctuations than the magnetic tape obtained in Comparative Example 1. This shows that the magnetic recording medium obtained by the present invention has excellent durability and heat resistance.

Patent applicant: Hitachi Maxell, Ltd. （・－・・

Claims (1)

[Claims] 1. A magnetic recording medium obtained by coating a substrate with a magnetic paint containing one selected from lead naphthenate or tin naphthenate, an isocyanate compound, and magnetic powder.