JPH0528461A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the resistance to corrosive gases of the magnetic recording medium obtained from a ferromagnetic alloy powder consisting essentially of iron by imparting sufficient oxidation resistance to the powder. CONSTITUTION:One or more kinds of (I) a polyurethane resin contg. a metal sulfonate, (II) a PVC copolymer resin contg. a metal sulfonate, (III) the alkaline- earth metal, aluminum, amine or iron salt of an alkylbenzenesulfonic acid and (IV) an alkenylsuccinic acid or its salt or its anhydride are incorporated into the magnetic layer of the magnetic recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium having a magnetic layer excellent in corrosion resistance.

[0002]

2. Description of the Related Art In recent years, high density recording has been required for magnetic recording media such as video tapes and floppy disks. Along with this, the use of ferromagnetic alloy powder containing iron as a main component (hereinafter referred to as metal powder) has increased.

It is generally said that metal powder has problems in the following points. Metal powder is easily oxidized (rusts easily) and requires anti-oxidation treatment.Metal powder is generally used for general-purpose γ-Fe ₂ O ₃ and Co-γ-Fe ₂ O ₃
Since the particle size is smaller than that of the above, it requires advanced dispersion technology. In particular, from the viewpoint of preventing the metal powder from being oxidized, JP-A-49-97
No. 738 (using higher fatty acid salt powder), JP-A-51-6349
No. 4 (using a vaporizable rust preventive), JP-A-51-104594 (using a silane compound), JP-A-51-109498 (using organic titanium), JP-A-55-84042 (higher fatty acid) And a combination of silicone oil), JP-A-55-111105 (metal powder is treated with a phosphoric acid ester), JP-A-56-1277.
No. 01 (Metal powder is treated with sulfur dioxide), JP-A-58-
No. 68233 (using a hydroquinone compound), JP-A-58-
155518 (using a specific amine compound), JP-A-60-
No. 7617 (using dialkyldithiophosphate),
JP-A-60-246019 (using a trialkylphosphine oxide) and the like are disclosed, but the performance is not sufficient. In particular, it is necessary to improve the corrosion resistance under high temperature and high humidity or in the presence of corrosive gas such as chlorine, nitrogen dioxide, sulfur dioxide and hydrogen sulfide.

[0004]

Means for Solving the Problems As a result of intensive studies made by the present inventors from the viewpoint of preventing the oxidation of metal powders in order to solve the above problems, as a result, a metal sulfonate metal group-containing polyurethane resin and a metal sulfonate metal group-containing polyvinyl chloride are obtained. Magnetic recording medium containing at least one of a copolymer resin, an alkaline earth metal salt of an alkylbenzene sulfonic acid, an aluminum salt, an amine salt or an iron salt, and an alkenylsuccinic acid or a salt thereof or an anhydride thereof in a magnetic layer. Have been found to have excellent corrosion resistance, and have completed the present invention.

That is, the present invention provides a magnetic recording medium comprising a non-magnetic support coated with a magnetic layer containing a ferromagnetic alloy powder containing iron as a main component and a binder as a main component. The present invention provides a magnetic recording medium characterized by containing one or more of each of the following compounds (I) to (IV). (I) Polyurethane resin containing metal sulfonate group (II) Polyvinyl chloride copolymer resin containing metal sulfonate group (III) Alkylbenzenesulfonic acid alkaline earth metal salt, aluminum salt, amine salt or iron salt (IV) alkenyl Succinic acid or its salt or its anhydride.

The (I) metal sulfonate-containing polyurethane resin and the (II) metal sulfonate-containing polyvinyl chloride copolymer resin used in the present invention are mainly added as a binder, and the metal sulfonate content is Both are 0.
It is possible to use one of about 01 to 100 μeq / mol. As the sulfonic acid metal group-containing polyurethane resin (I),
"Byron UR-8200""ByronUR-8300""Byron
UR-8700 "(both are trade names of Toyobo Co., Ltd.)," Mytec MX-9001 "," Mytec MX-9002 "and" Mytec "
It is easily available as a commercial product such as "MX-9090" (both are trade names of Mitsubishi Kasei Co., Ltd.). Further, as the polyvinyl chloride copolymer resin (II) containing a metal sulfonate group, "MR-1
It is easily available as a commercial product such as "10" (trade name of Nippon Zeon Co., Ltd.) and "MPR-DS" (trade name of Nisshin Chemical Co., Ltd.). It can also be synthesized according to a conventional method. For the magnetic recording medium of the present invention, the polymers (I) and (II) containing sodium sulfonate are usually used. In addition to the above, polyurethane other than the present invention, polyester, polyvinyl chloride other than the present invention, vinyl chloride / vinyl acetate copolymer other than the present invention, polyacrylonitrile, nitrile rubber, epoxy resin, alkyd resin, polyamide, polyacrylic Acid ester, polymethacrylic acid ester, polyvinyl acetate, polyvinyl butyral, polyvinylidene chloride, nitrification cotton, maleic acid-modified vinyl chloride / vinyl acetate copolymer, ethyl cellulose and the like can also be used in combination. These may be used alone, but are usually used as a mixture of two or more kinds. In addition, a plasticizer or a curing agent may be added to adjust the hardness of the resin.

The compounding amount of the (I) metal sulfonate-containing polyurethane resin and the (II) metal sulfonate-containing polyvinyl copolymer resin is generally (I) + based on 100 parts by weight of the magnetic powder.
(II) The total amount is 10 to 60 parts by weight, preferably 12 to 40 parts by weight. The (I) / (II) weight ratio is (I) / (II) = 5/95 to 95
/ 5, preferably 10/90 to 90/10. Even if the binder has the largest binding force, if it is less than 10 parts by weight, the strength of the magnetic coating film becomes weak and the adhesive force between the substrate and the magnetic coating film becomes insufficient. On the other hand, if the amount is more than 60 parts by weight, the concentration of the magnetic powder in the magnetic coating film becomes small and the reproduction output decreases, which is disadvantageous.

Alkaline earth metal salts such as calcium and barium, aluminum salts, amine salts or iron salts of (III) alkylbenzene sulfonic acid used in the present invention are prepared by reacting alkylbenzene sulfonic acid with a corresponding alkaline agent. Can be synthesized. As the raw material alkylbenzene sulfonic acid, one having a linear or branched alkyl group having 4 to 30 carbon atoms is used.

The (IV) alkenyl succinic acid used in the present invention has the following general formula:

[0010]

[Chemical 1]

(In the formula, R represents an alkenyl group having 4 to 30 carbon atoms, preferably 6 to 20 carbon atoms). Examples of the alkenylsuccinic acid salt include those represented by the following general formula:

[0012]

[Chemical 2]

(In the formula, R is the same as the above, and M is an alkali metal such as Na or K.) is used. Also, as a salt of alkenyl succinic acid

[0014]

[Chemical 3]

(In the formula, R is the same as above, and M'represents an alkaline earth metal such as Ca or Mg.).

As the alkenylsuccinic anhydride,

[0017]

[Chemical 4]

(Wherein R is the same as above) is used.

The compounding amount of the above (III) alkylbenzene sulfonate and (IV) alkenyl succinic acid or its salt or its anhydride is generally (III) + per 100 parts by weight of the magnetic powder.
(IV) The total amount is 0.005 to 8 parts by weight, preferably 0.003 to 3 parts by weight. The (III) / (IV) weight ratio is (III) / (I
V) = 1/99 to 99/1, preferably 5/95 to 95/5.

In the present invention, each of the above-mentioned components (I) to (IV) is added as one component of the paint during preparation of the paint.
Each component of (V) is dissolved in a solvent, metal powder is immersed in it and added in a form of surface-treated metal powder, each component of (I) to (IV) is dissolved in a solvent, and a magnetic layer is formed in advance. It is added by a method such as spraying. In this case, it is more effective to dissolve and spray with a lubricant.

As the components other than iron of the metal powder used in the present invention, elements such as Ni, Co, Ti, Si and Al are used. In addition to being contained as an alloy component of the metal powder, these elemental species may be present on the surface of the metal powder in the form of an inorganic compound such as an oxide, a sulfide, or a chloride. Also,
Many of these metal powders may form a thin oxide film in a weak oxidizing atmosphere for stabilization.

In the magnetic layer of the magnetic recording medium of the present invention, in addition to the above components, a lubricant, an abrasive, which is commonly used in this field,
Additives such as antistatic agents can be added.

The non-magnetic support used in the production of the magnetic recording medium of the present invention includes polyesters such as polyethylene terephthalate and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; celluloses such as cellulose triacetate and cellulose diacetate. Derivatives: polycarbonate; polyvinyl chloride; polyimide; plastics such as aromatic polyamide; metals such as Al and Cu; paper and the like. The form may be any of film, tape, sheet, disk, card, drum and the like. The surface of the support may be treated with corona discharge, radiation, ultraviolet rays or the like, or may be precoated with a suitable resin.

[0024]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Parts and% in the examples are based on weight unless otherwise specified.

Examples 1 to 5 <Formation of magnetic layer> The following paint formulations were manufactured by Igarashi Machine Co., Ltd.
After mixing for 4 hours with a 6-cylinder sand grinder manufactured by
Coronate L (trade name, Nippon Polyurethane Industry Co., Ltd.)
4 parts by weight of trimethylolpropane triisocyanate manufactured by Co., Ltd. was added, and the mixture was further mixed for 15 minutes, and then filtered to separate glass beads to prepare a magnetic paint. This paint is 32μ thick PET (polyethylene terephthalate)
A magnetic layer was formed on a PET film by coating the film so as to have a dry film thickness of 3 μm and subjecting the coating film to non-orientation treatment and drying. Then, the magnetic layer was calendered.・ Magnetic layer paint blended Fe-Ni alloy powder 100 parts (surface area 50m ² / g, Fe / Ni = 95/5, Hc = 1550 Oe) carbon black (average particle size 25nm) 3 α-Al ₂ O ₃ (average particle Diameter 0.3μ) 10 MR-110 ^{* 1} 11 Byron UR-8300 ^{* 2} 9 Octylmyristate 2 Compounds listed in Table 1 or Table 2 Compounding amount in Table 1 or Table 2 Methyl ethyl ketone 150 Cyclohexanone 100 (Note) * 1 MR- 110: Vinyl chloride copolymer containing metal sulfonate group (manufactured by Zeon Corporation) * 2 Byron UR-8300: Polyurethane resin containing metal sulfonate group (manufactured by Toyobo Co., Ltd.) <Evaluation of corrosion resistance> Magnetic 1cm of layered PET film
Punching was performed on a disk having a diameter of 30 ° C., relative humidity of 70%, and air containing 1 ppm of chlorine gas was stored for 7 days in a glass desiccator constantly fed at a flow rate of 1 liter / min. The static magnetic properties of the samples before and after storage were measured by an oscillating magnetometer with an applied magnetic field of 10 kOe, and the retention rate of the saturation magnetic flux density was used as a guideline for corrosion resistance. The larger the retention value, the better the corrosion resistance. The results are shown in Tables 1 and 2.

Comparative Examples 1 to 3 In the magnetic layer coating composition, the compounds shown in the Examples column of Tables 1 and 2 were replaced with the compounds shown in the columns of Comparative Examples 1 to 3 of Table 2 to prepare magnetic layer coatings. The retention rate of the saturation magnetic flux density was measured in the same manner as in Examples 1 to 5 except that the corrosion resistance was evaluated. The results are shown in Table 2.

[0027]

[Table 1]

[0028]

[Table 2]

(Results) (I) Polyurethane resin containing metal sulfonate group, (II) Polyvinyl chloride copolymer resin containing metal sulfonate group, (III) Alkaline earth metal salt of alkylbenzene sulfonic acid, aluminum salt, A PET film coated with a magnetic coating containing an amine salt or iron salt and (IV) alkenyl succinic acid or a salt thereof or an anhydride thereof has a high saturation magnetic flux density retention rate,
A magnetic recording medium having excellent corrosion resistance can be provided.

Claims (1)

Claim: What is claimed is: 1. A magnetic recording medium comprising a non-magnetic support coated with a ferromagnetic alloy powder containing iron as a main component and a magnetic layer containing a binder as a main component. A magnetic recording medium characterized in that the magnetic layer contains at least one of the following compounds (I) to (IV). (I) Polyurethane resin containing metal sulfonate group (II) Polyvinyl chloride copolymer resin containing metal sulfonate group (III) Alkylbenzenesulfonic acid alkaline earth metal salt, aluminum salt, amine salt or iron salt (IV) alkenyl Succinic acid or its salt or its anhydride