JPS6194234A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To reduce a decrease in the reproduction output and to improve the durability by providing a magnetic layer on a nonmagnetic supporting body, and furnishing a resinous protective layer contg. fine powder of a polymer contg. fluorine on the magnetic layer. CONSTITUTION:A magnetic layer is provided on a nonmagnetic supporting body, and a resinous protective layer contg. the fine powder of a fluorine-contg. polymer is further furnished on said layer to obtain a good-quality magnetic recording material having excellent resistance to abrasion and impact without deteriorating the magnetic characteristic of the magnetic layer. Polyethylene terephthalate, polypropylene, synthetic paper, aluminum foil, etc. can be exemplified as the nonmagnetic supporting body, the magnetic layer is composed essentially of magnetic particles and a binder, and gamma-Fe2O3, Fe3O4, etc. are typified as the magnetic particle. Besides, a vinyl chloride-acetate copolymer, a vinyl chloride-vinylidene chloride are used as the binder. The fine powdery body of polytetrafluoroethylene, etc. can be exemplified as the fine powder of a fluorine-contg. polymer used for the protective layer. The amt. of the fluorine- contg. fine powder to be added to the resinous binder for the protective layer is appropriately regulated to 1-30wt%, based on the resinous binder.

Description

TECHNICAL FIELD The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium in which a specific protective layer is provided on a magnetic layer.

Prior Art Most magnetic recording media, such as magnetic tapes, floppy disks, railway ticket gates/commuter passes, and cash cards, consist of magnetic particles and a binder as main components on a non-magnetic support such as paper or plastic film. It is equipped with a magnetic layer.

By the way, as can be seen from the above, this type of magnetic recording medium is used in various businesses, and for recording and recording.
During playback, the magnetic head or guide member is violently slid or contacted, and therefore, even though it is not used frequently, the magnetic layer is worn out and the playback output decreases, which can easily cause malfunctions. It was recognized as a trend.

In order to eliminate such inconvenience as much as possible,
For example, (a) 8 IC% AZ, O,, Or snow 0 in the magnetic layer.
Attempts have been made to add abrasive agents such as @, or lubricants such as silicone or wax, but these methods (a) and (b) do not soften the magnetic layer film. The actual situation is that the amount of the additive used is inevitably limited because phenomena such as tree-dooing and the like tend to occur, and sufficient effects cannot be brought about.

In addition, as other means, for example, a protective layer consisting of a lubricant, and (e) a protective layer in which abrasive particles are dispersed in a resin binder, or (e) logging or mixing of various resin binders may be used. It has also been proposed to provide a protective layer, but even with these methods, good results have not yet been obtained. That is, in (c) above, the life of the protective layer is short; <, - above), the head wears severely, and in (e) above, wear resistance is good but impact resistance S is poor, or vice versa. Moreover, the durability is still insufficient.

Purpose The purpose of the present invention is to eliminate the above-mentioned defects, to significantly reduce the drop in playback output even after multiple recording and playbacks, and to
Moreover, it provides a high quality magnetic recording medium with excellent durability.

Structure The magnetic recording medium of the present invention is characterized in that it comprises a magnetic layer on a non-magnetic support, and a resin protective layer containing fine powder of fluorine-containing 4-rimer thereon.

As a result of various studies to achieve the above object, the inventors of the present invention found that if a resin protective layer containing fine powder of a fluorine-containing polymer is provided on the magnetic layer, the magnetic layer will not lose its magnetic properties. ,
It has also been found that a high quality magnetic recording material with excellent abrasion resistance and impact resistance can be obtained. The present invention was completed based on such knowledge.

To explain the invention in more detail below, other parts of the present invention except for the protective layer, that is, the nonmagnetic support and the magnetic layer itself are the same as those of the conventional ones. Therefore, the magnetic recording of the present invention Examples of the nonmagnetic support used in the medium include resin films such as polyethylene terephthalate, polypropylene, cellulose triacetate, cellulose diacetate, and polyimide, paper, synthetic paper, and aluminum foil.

The magnetic layer is mainly composed of magnetic particles and a binder. The magnetic particles that are one component of this layer are r
-Fe HQs, Fe3O4, Co containing r -FelO
l, Co-containing Fe, 04, Co-adhered 1- Fe10
Typical examples include 〇 Inders, which are other components that constitute the magnetic layer together with magnetic particles, are those commonly used in this field,
For example, vinyl chloride-di-vinyl acetate copolymer, vinyl chloride-
Vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-styrene copolymer,
Urethane elastomer, Ise nylbutyral, Cell o
-Sufusef-) f-rate, nitrocellulose, polyester resin, styrene-butadiene copolymer, butadiene-acrylonitrile copolymer, etc. are used. Further, an electron beam curable binder may be used. According to a method for manufacturing a magnetic recording medium that uses an electron beam curable binder to form a magnetic layer, it is possible to prevent solid content in the magnetic paint (magnetic layer forming liquid) from coagulating, improve pot life, and simplify the manufacturing process. It is advantageous in terms of energy efficiency, energy saving, etc. Furthermore, a combination of an electron beam curable binder and a thermosetting binder can also be effectively used.

As a typical example of the above electron beam curable/S inder,
Compounds having ester skeletons, ether skeletons, urethane skeletons, epoxy skeletons, etc., specifically oligomers or pre-4 polymers having groups such as acryloyl groups and methacryloyl groups, such as urethane acrylate oligomers, polyester/acrylate prepolymers, polyester/ Examples include acrylate prepolymer, epoxy/acrylate pre-I remer, I-rester/urethane/acrylate prepolymer, etc. Examples of the thermosetting resin include urethane resins, epoxy resins, cellulose resins, and mixtures of these with vinyl chloride resins, vinylidene chloride resins, and the like.

The magnetic recording material of the present invention is one in which a special protective layer is provided on such a magnetic layer, and this protective i1! ! The layer is mainly composed of fluorine-containing polymer fine powder dispersed in a resin binder. The protective film of such a resin containing fine fluorine-containing polymer powder is tough and exhibits excellent abrasion resistance and impact resistance.

The fine powder of the fluorine-containing polymer used in the protective layer of the present invention includes polytetrafluoroethylene, ? Lifluorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene rubber fluoroalkyl vinyl ether copolymer, chlorotrifluoro There is a fine powder of ethylene to ethylene copolymer (a commercially available product, for example, manufactured by Asahi Glass Co., Ltd.). ) can be exemplified.

On the other hand, various thermosetting resins and thermoplastic resins can be used as resin inders used in the protective layer. Examples of thermosetting resins include epoxy resins, phenol resins, melamine resins, and urea resins. In addition, thermoplastic resins include celluloses, acetal resins, acrylic resins, vinyl chloride resins, vinylidene chloride resins, vinyl acetate resins and their copolymers, polyester resins, polystyrene resins and their copolymers, Examples include polyurethane resin, polycarbonate resin, polyamide resin, and fluororesin.

The amount of fluorine-containing polymer fine powder added to the resin/inder for the protective layer as described above is 1 to 3 to the resin inder.
A range of 0% by weight (preferably from 5 to 20% by weight) is suitable. If the amount added is less than 5%, the abrasion resistance and impact resistance will decrease, and if the amount added exceeds 20%, the adhesive force to the magnetic layer will decrease. In addition, the particle size of the fluorine-containing polymer fine powder is 0.
, 5 to 5 pC, preferably 1 to 3 p).

In order to actually produce the magnetic recording material of the present invention, a magnetic layer forming liquid and a protective layer forming liquid are prepared separately, and these are sequentially applied onto a support and dried (in the case of forming a protective layer, drying is followed by heat curing). ) Just let it happen. The drilling used to prepare these forming solutions includes acetone, methyl ethyl ketone,
Cyclohexane, acetic acid, toluene, xylene,
Examples include hexane and heptane.

Further, as a coating method, gravure coating, lino-roll coating, bar code coating, knife coating, etc. can be appropriately employed.

The thickness of the magnetic layer is about 1 to 20/l, and dispersants, antistatic agents, lubricants, polishing agents, hardening agents, etc. commonly used in this field may be added as appropriate.

On the other hand, the thickness of the protective layer is about 0.5 to 5p.

Next, the present invention will be explained by examples. Note that all parts are parts by weight.

Example 1 75 parts of y-FelOl powder, 3 parts of lecithin, 15 parts of vinyl chloride-vinyl acetate-vinyl alcohol copolymer,
A mixture consisting of 7 parts of polyurethane elastomer and 190 parts of toluene/methyl ethyl ketone mixed solvent (volume ratio 1:1) was dispersed in a ball mill for 24 hours, and then 3 parts of I-lysocyanate compound was added and kneaded to prepare a magnetic paint. .

Next, the above magnetic coating material was applied onto a polyester film (substrate) having a thickness of 188/l and dried to form a magnetic layer having a thickness of approximately 13/l.

On the other hand, a mixture consisting of the following composition was dispersed in a ball mill for 24 hours to obtain a coating for a protective layer, and this was applied onto the magnetic layer and dried to form a protective layer with a thickness of approximately 3 μm. It was cut into specified dimensions and made into magnetic cards.

Protective layer composition: I-lyester resin (manufactured by Toyobo Co., Ltd.) (Iron 200)
10 parts Example 2 Acrylic resin as a tumor layer paint (Aron 8-2060 manufactured by Toagosei Co., Ltd.)
10 parts fluorine-containing polymer fine powder (same as Example 1)
A magnetic card was prepared in the same manner as in Example 1, except that a composition consisting of 1 part toluene and 25 parts of meth-I-reethyl ketone mixed solvent (weight ratio 1/1) was used.

Yield Example 1 A magnetic card was prepared in the same manner as in Example 1 except that the protective layer was formed of polyethylene wax alone.

Comparative Example 2 The protective layer was a mixture of acrylic resin and nitrocellulose (
A magnetic card was prepared in the same manner as in Example 1, except that the magnetic card was formed using a magnetic card with a weight ratio of 1:1).

Next, the above four types of magnetic cards were tested for abrasion resistance and impact resistance, and the results shown in the table below were obtained.

Test method Abrasion resistance: Strong with stainless steel step under 5oot load? A wear test was conducted to show the number of surfaces until the adhesive layer partially peeled off.

Impact resistance: A drop test was performed on the same spot using a stainless steel chip under a load of 200, and the number of times until the protective layer was peeled off was shown.

Effects As is clear from the above, the magnetic recording medium of the present invention has significantly better wear resistance and impact resistance than the conventional magnetic recording medium. This is presumed to be due to the fine powder of fluorine-containing polymer added to the barrier layer acting as a solid lubricant.

Claims (1)

[Claims] 1. A magnetic recording medium comprising a magnetic layer on a non-magnetic support and a resin protective layer containing fine powder of a fluorine-containing polymer thereon.