JPS59172131A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the resistance of a magnetic layer to wear and heat by adding naphthenic and salt and urethanated tertiary amine 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. naphthenic acid salt, urethanated tertiary amine, isocyanate compd. and magnetic powder is coated on a base body. When the napthenic acid salt and urethanated tertiary amine are added into the magnetic coating contg. the isocyanate compd., the cross-linking 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 and these compd. and resin the quickly cross-linked 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 napthenic acid salt and the urethanated tertiary amine to be used is preferably in a range of 0.1-10wt% by the total weight of the binder component. The compounding ratio of the naphthenic acid salt and the urethanated tertiary amine is made preferably in a range of 1:9-9:1 by weight.

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 worn out, so it is required to have excellent durability with little wear.

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

However, by adding this zinc octenoate 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 as a result, they added naphthenic acid salts and urethanized tertiary amines to a magnetic paint containing an isocyanate compound, and applied this to a substrate. When a magnetic layer is formed, the hardening accelerating effect of the naphthenate and urethanized tertiary amine is superior to that of conventional zinc octenoate, so the crosslinking reaction of the isocyanate compound is quickly promoted, increasing the strength of the magnetic layer. It was discovered that the magnetic layer can be sufficiently strengthened and the wear resistance and heat resistance of the magnetic layer can be sufficiently improved, leading to the present invention.

The naphthenate and urethanized tertiary amine used in this invention have a greater ability to promote crosslinking reactions between isocyanate compounds and other binder components containing active hydrogen than conventional zinc octenoate. Therefore, when this type of naphthenate and urethanized tertiary amine is added to a magnetic paint containing an isocyanate compound, the isocyanate compound and vinyl chloride resin, polyester resin, polyurethane resin, The crosslinking reaction with the binder resin containing active hydrogen such as polyvinyl acecool resin and cellulose resin is further promoted, and these are quickly crosslinked into a network, increasing the strength of the magnetic layer and improving wear resistance. and heat resistance is improved. In addition, this type of naphthenate and urethanized tertiary amine have good compatibility with commonly used binder resins, so they are well mixed into magnetic paints and have a sufficient effect of promoting the crosslinking reaction. It is demonstrated in Such an effect is due to the concentration of naphthenate and urethanized tertiary amine at 0.1% by weight based on the total amount of binder components.
The effect becomes more pronounced as the amount added increases, but if the amount exceeds 10% by weight, it may bleed out to the surface of the magnetic layer and deteriorate the electromagnetic conversion characteristics. The amount of tertiary amine used is 0.1 to 0.1 to the total amount of binder components.
It is preferably within the range of 10% by weight. Further, the blending ratio of naphthenic acid salt and urethanized tertiary amine is preferably within the range of 1:9 to 9:1 in terms of weight ratio,
If it deviates from this range, the desired effect will not be obtained.

The urethanized tertiary amine used in this invention is a compound of a low molecular weight polyurethane with a molecular weight of 10,000 or less and an aliphatic amine or an aromatic amine. , HR, and QS.

The isocyanate compound is not particularly limited as long as it has an isocyanate group; for example, 2.4
-) Diisocyanate compounds such as lylene diisocyanate, m-phenylene diisocyanate, and 1,5-naphthalene diisocyanate, and trifunctional low molecular weight isocyanate compounds usually obtained by reacting 1 mol of triol with 3 mol of diisocyanate are suitable. When these isocyanate compounds and other binder resins containing active hydrogen are used together, they crosslink and strengthen the magnetic layer. When a urethanized tertiary amine is used in combination, the crosslinking reaction is further promoted, so that the strength of the magnetic layer is further strengthened and the abrasion resistance and heat resistance of the magnetic layer are further improved. Specific examples of trifunctional low molecular weight isocyanate compounds include Coronae) L manufactured by Nippon Polyurethane Industries, Ltd. and Takenate D1 manufactured by Narita Pharmaceutical Industries, Ltd.
02, Desmodule manufactured by Bayer, and Rispon 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 r-Fe203 powder, Fe3O4 powder, Co-containing TFe203 powder, CO-containing Fe3O4 powder, CrO2 powder, as well as Fe powder, CO powder, Fe-N
Various conventionally known magnetic powders such as metal powders such as i-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 invention will be described.

Example 1 Co-containing Fe203 powder 80 parts by weight VAGH
(Vinyl chloride 10-vinyl acetate-vinyl alcohol copolymer manufactured by IJ, C, C, Co., Ltd.) Bandesox T-5201 (Urethane elastomer manufactured by Nippon Ink Co., Ltd.) Coronate Shichi Nippon Polyurethane 2 Trifunctional, manufactured by Nippon Ink Co., Ltd. Lead naphthenate 0.5〃Crispon HM (Dainippon Ink 0.5〃Urethanized tertiary amine manufactured by Kagaku Kogyo Co., Ltd.) Methyl isobutyl ketone 50〃Toluene
50 This composition was mixed and dispersed in a ball mill for 72 hours to prepare a magnetic paint, and this magnetic paint was applied onto a polyester base film with a thickness of 12 μm to 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 in the composition of the magnetic paint in Example I, the amounts of lead naphthenate and Crisbon HM used were changed as shown in Table 1 below.

Table 1 Comparative Example 1 A magnetic coating was prepared in the same manner as in Example 1, except that in the composition of the magnetic paint in Example 1, zinc octate was used in the same amount as the total amount of lead phthenate and Crisbon HM. I made a tape.

Regarding the magnetic tapes obtained in each example and comparative example,
Tested for heat resistance and abrasion resistance. The heat resistance test was carried out 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 36 mm, and heating it for 60 minutes.
After storing it 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, and no adhesion was observed. The cases were evaluated as (◎), the cases where it was rarely observed (○), the cases where it was observed slightly (△), and the cases where it could not be disentangled at all (x).

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 4 all had better heat resistance and smaller output fluctuations than the magnetic tape obtained in Comparative Example. It can be seen from the above that the magnetic recording medium obtained by the present invention has excellent durability and heat resistance11.

Patent applicant: Hitachi Maxell, Ltd. Agent Takaoka-Haru-(”’, j7’ 1'L,! −・ i, +, ---:X'', .

Claims (1)

[Claims] 1. A magnetic recording medium obtained by applying a magnetic paint containing a naphthenate, a urethanized tertiary amine, an isocyanate compound, and a magnetic powder onto a substrate.