JPH0554364A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the sufficient oxidation preventive performance of the ferromagnetic alloy powder of the magnetic recording medium obtd. by using the ferromagnetic alloy powder essential consisting of iron and to improve the corrosion resistance to corrosive gases. CONSTITUTION:This recording medium contains (I) a polyurethane resin contg. the metal base of sulfonic acid, (II) a polyvinyl chloride copolymer resin contg. the metal base of sulfonic acid, (III) the fatty acid ester of the polyhydric alcohol selected from glycerol fatty acid ester, pentaerithritol fatty acid ester and sorbitan fatty acid ester, and (IV) respectively >=1 kinds of alkenyl succinic acid or its salt or its anhydride in its magnetic layer.

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, advanced dispersion technology is required. Particularly from the viewpoint of preventing the oxidation of the metal powder, JP-A-49-97738 (using a higher fatty acid salt powder),
JP-A-51-63494 (using a volatile anticorrosive agent), JP-A-5-63
1-104594 (using a silane compound), JP-A-51-109
498 (using organic titanium), JP-A-55-84042
(Combination of higher fatty acid and silicone oil), JP-A-55-1
No. 11105 (Metal powder is treated with phosphoric acid ester),
JP-A-56-127701 (treating metal powder with sulfur dioxide), JP-A-58-68233 (using a hydroquinone compound), JP-A-58-155518 (using a specific amine compound), JP-A JP-A-60-7617 (using a 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. The magnetic layer contains at least one of a copolymer resin, a glycerin fatty acid ester, a fatty acid ester of a polyhydric alcohol selected from pentaerythritol fatty acid ester and sorbitan fatty acid ester, and an alkenylsuccinic acid or a salt thereof or an anhydride thereof. They have found that the magnetic recording medium has excellent corrosion resistance, and 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) Fatty acid ester of polyhydric alcohol selected from glycerin fatty acid ester, pentaerythritol fatty acid ester and sorbitan fatty acid ester ( IV) Alkenyl succinic acid or its salt or its anhydride.

The (I) sulfonic acid metal group-containing polyurethane resin and (II) sulfonic acid metal group-containing polyvinyl chloride copolymer resin used in the present invention are mainly added as a binder, and the sulfonic acid metal group content is 0.01 for both
Around 100 μeq / mol can be used. 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-110" (product name of Nippon Zeon Co., Ltd.), "MPR-DS"
It is easily available as a commercial product such as "MPR-DSA" (both are trade names 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 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.

The fatty acid ester of polyhydric alcohol selected from (III) glycerin fatty acid ester, pentaerythritol fatty acid ester and sorbitan fatty acid ester used in the present invention is a monoester, diester,
Any of the triesters may be used, and various kinds of these esters are commercially available and are easily available. Specific examples are shown below. As glycerin fatty acid ester, there are Leodol MS-50 and Leodol MS-60.
, Leodol SEM, Leodol MO-60, Emazole MO-
50, Exepearl TGO, Exepearl G-MB, Homotex AC, Homotex PT, Homotex LA, Exel 70
00, Coconard RK, Coconard MK (all manufactured by Kao Corporation)
Etc. As pentaerythritol fatty acid ester, Exepearl PE-MO, Exepearl PE-MS
(These are manufactured by Kao Corporation) and the like. Further, as sorbitan fatty acid ester, Leodol SP-L10, Leodol SP-P10, Leodol SP-S10, Leodol SP-S30, Leodol SP-O10, Leodol SP-O30, Leodol AS-10
, Leodol AO-10, Leodol AO-15, Emazol L
-10 (H), Emazol L-10, Emazol P-10, Emazol S-10, Emazol S-20, Emazol O-15R, Emazol L-10 (F), Emazol P-10 (F), Emazol S- 10 (F)
, Emazol S-30 (F), Emazol O-10 (F), Emazol O-30 (F), Emazol B, Emazol E (above Kao
Co., Ltd.) and the like.

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-mentioned (III) fatty acid ester of polyhydric alcohol and (IV) alkenylsuccinic acid or its salt or its anhydride is generally (III) + per 100 parts by weight of magnetic powder.
(IV) 0.005 to 8 parts by weight, preferably 0.03
~ 3 parts by weight. The (III) / (IV) weight ratio is (II
I) / (IV) = 1/99 to 99/1, preferably 5/95 to 95/5
Is.

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 dipped in it and added in a form of surface-treated metal powder, (I) to (IV) are dissolved in a solvent, and a magnetic layer formed in advance is added. 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 4 <Formation of magnetic layer> The following paint formulations were manufactured by Igarashi Machine Co., Ltd.
After mixing with a 6-cylinder sand grinder manufactured by Co., Ltd. for 4 hours,
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 52m ² / g, Fe / Ni = 92/8, Hc = 1550 Oe) carbon black (average particle diameter 40nm) 1 α-Al ₂ O ₃ (average particle Diameter 0.3μ) 10 MR-110 ^{* 1} 10 Byron UR-8200 ^{* 2} 10 Oleylolate 4 Compounds listed in Table 1 Compounding amount in Table 1 Methyl ethyl ketone 150 Cyclohexanone 100 (Note) * 1 MR-110: Sulfonate metal base included Vinyl chloride copolymer (manufactured by Nippon Zeon Co., Ltd.) * 2 Byron UR-8200: Metallic sulfonate-containing polyurethane resin (manufactured by Toyobo Co., Ltd.) <Evaluation of corrosion resistance> A PET film with a magnetic layer formed 1 cm
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 Table 1.

Comparative Examples 1 to 3 A magnetic layer coating composition was prepared by changing the compounds described in the Examples column of Table 1 to the compounds shown in the Comparative Examples 1 to 3 column of Table 1 in the formulation of the magnetic layer coating composition. The retention rate of the saturation magnetic flux density was measured in the same manner as in Examples 1 to 4, and the corrosion resistance was evaluated. The results are shown in Table 1.

[0027]

[Table 1]

(Results) (I) Polyurethane resin containing metal sulfonate group, (II) Polyvinyl chloride copolymer resin containing metal sulfonate group, (I
II) Fatty acid ester of polyhydric alcohol selected from glycerin fatty acid ester, pentaerythritol fatty acid ester and sorbitan fatty acid ester, and (IV) alkenylsuccinic acid or its salt or its anhydride 1
A PET film coated with a magnetic coating material containing one or more species can provide a magnetic recording medium having a high saturation magnetic flux density retention rate and excellent corrosion resistance.

Claims (1)

[Claims] 1. 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. A magnetic recording medium containing one or more of each of the compounds (I) to (IV). (I) Polyurethane resin containing metal sulfonate group (II) Polyvinyl chloride copolymer resin containing metal sulfonate group (III) Fatty acid ester of polyhydric alcohol selected from glycerin fatty acid ester, pentaerythritol fatty acid ester and sorbitan fatty acid ester ( IV) Alkenylsuccinic acid or its salt or its anhydride