JPH0215421A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent sticking of a cutting scrap by cutting the raw sheet of the magnetic recording medium having a specified Young's modulus in the transverse direction while cleaning a shearing type rotary blade. CONSTITUTION:The shearing type rotary blade 4 is used in the state of removing the deposits thereof while the blade is cleaned by a cleaning member 5, by which the raw sheet of the magnetic recording medium having 400-800 Young's modulus in the transverse direction is cut and the magnetic recording medium is formed. The cutting scrap does not, therefore, stick to the raw sheet. The magnetic recording medium which has less drop-out and obviates the generation of magnetic head clogging is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a magnetic recording medium. More specifically, the present invention relates to a method of manufacturing a magnetic recording medium that is free from adhesion of cutting residue and has good electromagnetic characteristics.

[Prior Art and Problems to be Solved by the Invention] In recent years, magnetic recording media have been widely used in various applications such as video tapes, audio tapes, and floppy disks.

These magnetic recording media are usually manufactured by cutting a raw magnetic recording medium into a predetermined shape.

Examples of the cutting method include cutting using a shearing rotary blade of a cutting device.

In the above-mentioned method of cutting using a shear type rotary blade, cutting scum and the like adhere to the shear type rotary blade by cutting the original magnetic recording medium.

Then, by cutting the original magnetic recording medium with a shearing rotary blade on which cutting debris, etc. have adhered, the cutting debris, etc. are removed from the cut magnetic recording medium (particularly on the cut surface of the magnetic recording medium and its vicinity). ) is a problem.

Cutting debris adhering to the magnetic recording medium poses problems such as causing dropout of the magnetic recording medium and clogging of the head, resulting in a decrease in RF specific output.

Therefore, in order to prevent cutting debris from adhering to the magnetic recording medium, a method is used to remove the cutting debris from the shearing rotary blade by vacuuming the interior of the cutting device. Consideration has been given to using a method in which a nonwoven fabric is applied to the surface of the magnetic recording medium after cutting to remove cutting debris and the like adhering to the surface of the magnetic recording medium.

However, the method of evacuating the inside of the cutting device has a problem in that it is difficult to sufficiently remove the cutting scum and the like adhering to the shearing rotary blade.

Furthermore, the method of applying a nonwoven fabric to the surface of the magnetic recording medium after cutting also has the problem that it is difficult to sufficiently remove the cutting residue and the like adhering to the magnetic recording medium.

This invention has been made based on the above circumstances.

In other words, an object of the present invention is to eliminate head clogging and
Another object of the present invention is to provide a method for manufacturing a magnetic recording medium that has excellent electromagnetic characteristics such as no adhesion of cutting residue and no dropouts.

[Means and operations for solving the above problems] In order to solve the above problems, the inventor has made extensive studies and has adopted a magnetic recording medium material having specific physical properties,
The manufacturing method of magnetic recording media that has a specific cutting process has no head clogging, no adhesion of cutting residue, etc.
The present invention was achieved by discovering that a magnetic recording medium having excellent electromagnetic characteristics such as no dropout can be manufactured.

That is, the configuration of the present invention for solving the above problem is to remove the deposits on the shear type rotary blade with a cleaning member while cleaning the original magnetic recording medium having a Young's modulus in one width direction of 400 to 800 kg/m2. This is a method for manufacturing a magnetic recording medium, which is characterized by cutting.

-1 Magnetic Recording Media Original Fabric -The magnetic recording medium original fabric is formed by providing a magnetic layer containing ferromagnetic powder and a binder on a non-magnetic support.

One of the important points in this invention is that the Young's modulus in the width direction of the original magnetic recording medium is 400 to 800 kg/m2.
and preferably 450 to 700 kg/s Layer 2.

The width direction of the magnetic recording medium original fabric is a direction perpendicular to the cut surface of the magnetic recording medium, for example, a direction perpendicular to the arrow direction which is the moving direction of the magnetic recording medium original fabric 3 shown in FIG. This is the lateral direction of the original magnetic recording medium.

In this invention, the Young's modulus in the width direction is 400 to 800.
kg/ms", it is possible to extremely reduce the generation of cutting debris during cutting.

A raw magnetic recording medium having such a specific Young's modulus can be manufactured from a nonmagnetic support, a eutectic powder, and a binder as described below.

(Nonmagnetic Support) Materials for forming the nonmagnetic support include, for example, polyethylene terephthalate and polyethylene-2,6-
Mention may be made of polyesters such as naphthalates, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, and plastics such as polycarbonates. Further, metals such as Cu, An, and Zn, glass, and various ceramics such as so-called new ceramics (eg, boron nitride, silicon carbide, etc.) can also be used.

There is no particular restriction on the form of the non-magnetic support, and it may be in the form of a tape, sheet, cart, etc.
Various materials can be selected and used depending on the form and as needed.

When the support is in the form of a tape or sheet, the thickness is usually 3 to 100 μm, preferably 5 to 50 μm.
It is Lm.

A back coat layer may be provided on the surface (back surface) of the nonmagnetic support on which the magnetic layer is not provided for the purpose of improving the running properties of the magnetic recording medium, preventing electrification, preventing transfer, and the like.

Furthermore, an intermediate layer (for example, an adhesive layer) can be provided on the surface of the non-magnetic support on which the magnetic layer is provided, for the purpose of improving the adhesion between the magnetic layer and the non-magnetic support.

(magnetic layer) The magnetic layer is provided on the non-magnetic support.

The magnetic layer is a layer formed by dispersing ferromagnetic powder in a binder.

Examples of the ferromagnetic powder include Chi-Fe. 03,G
o-containing y FeJ*, FeJ4, Go-containing y
Iron oxide magnetic powder such as FezOn, Fe-AJI alloy powder, Fe-A-1 alloy powder, Fe-N1-Go
Alloy powder, Fe-Mn-Zn alloy powder, Fe-Ni-Z
n alloy powder, Fe-Go-Ni-Cr alloy powder, Fe-
Co-N1-1 alloy powder, Co-Ni alloy powder and G
Examples include o-1 alloy powder, ferromagnetic alloy powder whose main component is a ferromagnetic metal such as Fe, Ni, Co, etc.

There is no particular restriction on the shape of the ferromagnetic powder, and for example, it may be acicular, spherical, or ellipsoidal.

The binder includes, for example, thermoplastic resins, thermosetting resins, reactive resins, etc., which are conventionally used in magnetic recording media.
Electron beam irradiation curable resins or mixtures thereof can be used.

Examples of the thermoplastic resin include polyvinyl chloride,
Polyvinyl acetate, partially terminated polyvinyl acetate, urethane resin, urethane elastomer, various modified urethane resins, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic acid ester-acrylonitrile copolymer,
Acrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-ethylene copolymer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymer, polyester resin, vinyl chloride-acrylic acid ester copolymer , chloride and nyl-methacrylic acid ester copolymers, amino resins, and synthetic rubber-based thermoplastic resins.

These may be used alone or in combination of 2.1 or more.

As the thermosetting resin or reactive resin.

For example, phenolic resins, epoxy resins, polyurethane curable resins, urea resins, melamine resins, alkyd resins, silicone resins, acrylic reaction resins, mixtures of high molecular weight polyester resins and incyanate prepolymers,
Examples include mixtures of methacrylate copolymers and diisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanate, and polyamine resins.

These may be used alone or in combination of two or more.

Examples of the electron beam curable resin include unsaturated prepolymers such as maleic anhydride type, urethane acrylic type, epoxy acrylic type, polyester acrylic type, polyether acrylic type, polyurethane acrylic type, polyamide acrylic type; ether acrylic type; , urethane acrylic type, epoxy acrylic type, phosphate ester acrylic type, aryl type, and hydrocarbon type.

These may be used alone or in combination of two or more.

In this invention, the various resins described above may be used as they are as a binder, but furthermore, a curing agent may be used together with the various resins described above to serve as a binder.

Examples of the curing agent include bifunctional isocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and hexane diisocyanate, and 3 such as Coronate L (trade name: manufactured by Nippon Polyurethane Industries) and Desmodur Shikaku (trade name: manufactured by Bayer). Examples include polyisocyanate-based curing agents that have been conventionally used as curing agents, such as polyisocyanates and urethane prepolymers containing isocyanate groups at both ends.

The blending ratio of the ferromagnetic powder and the binder is, for example, 5 to 400 parts by weight per 100 parts by weight of the ferromagnetic powder. If the amount of the binder is too large, the amount of ferromagnetic powder mixed will be low, which may reduce the recording density of the magnetic recording medium. If it is too small, the strength of the magnetic layer will be reduced, causing the magnetic recording medium to The running durability of the vehicle may be reduced.

In this invention, in addition to the ferromagnetic powder and the binder, the magnetic layer forming components may include a lubricant, an abrasive, an antistatic agent, and the like.

Examples of the lubricant include fatty acids, fatty acid esters, silicone lubricants, fatty acid-modified silicone lubricants, fluorine-based lubricants, liquid paraffin, squalane, carbon black, graphite, carbon black graft polymers, molybdenum disulfide, and Examples include tungsten sulfide.

These may be used alone or in combination of two or more.

The amount of the lubricant used is usually 10 parts by weight or less per 100 parts by weight of the ferromagnetic powder.

Examples of the polishing agent include aluminum oxide, titanium oxide (TiO1TiO2), and silicon oxide (SiO1S).
Examples include inorganic powders such as iO□), silicon nitride, chromium oxide, and boron carbide, and organic powders such as benzoguanamine resin powder, melamine resin powder, and phthalocyanine compound powder.

These may be used alone or in combination of two or more.

The average particle diameter of the abrasive is usually 0.1 to 1.0 IL.
It is m.

The amount of the abrasive is usually 0.5 to 20 parts by weight per 100 parts by weight of the ferromagnetic powder.

Examples of the antistatic agent include conductive powders such as graphite, carbon black, tin oxide-antimony oxide compounds, tin oxide-titanium oxide-antimony oxide compounds, and carbon black graft polymers; natural surfactants such as saponin; Nonionic surfactants such as alkylene oxide type, glycerin type, and glycidol type: higher alkylamines, quaternary pyridine, and other heterocycles.

Cationic surfactants such as phosphoniums and sulfoniums: Anionic surfactants containing acidic groups such as carboxylic acids, sulfonic acids, phosphoric acids, sulfuric acid ester groups, and phosphoric ester groups Niamino acids, aminosulfonic acids, sulfuric acid and phosphoric acid esters of amino alcohols Examples include amphoteric surfactants such as .

These may be used alone or in combination of two or more.

The amount of the antistatic agent added is usually 0.5 to 20 parts by weight per 100 parts by weight of the ferromagnetic powder.

Note that the lubricant, antistatic agent, etc. do not have an independent effect, but may act as a - compound or a lubricant and an antistatic agent, for example.

Therefore, the above classifications in this invention indicate the main effects, and are not limited by the effects of the compounds in one classification or the effects shown in the classification.

(Manufacture of magnetic recording medium original fabric) The magnetic recording medium original fabric is made of, for example, the ferromagnetic powder,
It can be manufactured by preparing a magnetic paint by cross-dispersing magnetic layer forming components such as a binder in a solvent, and then applying the obtained magnetic paint to one side of the non-magnetic support and drying it.

Examples of the solvent used for kneading and dispersing the magnetic layer forming components include acetone and methyl ethyl ketone (MEK).
, methyl isobutyl ketone (to MIB) and rγcyclo to jfk1 no rabbit 4 I ++.

Alcohols such as ethanol, propatool and butanol; esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, propyl acetate and ethylene glycol monoacetate; diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, dioxane, etc. ether type; aromatic hydrocarbons such as benzene, toluene and xylene; halogenated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin and dichlorobenzene, etc. .

When kneading the composition of the magnetic paint components, the ferromagnetic powder and other magnetic paint components are added simultaneously or individually in a mixed manner. For example, first, the ferromagnetic powder is added to a solution containing a dispersant, and after kneading for a predetermined time, the remaining components are added and continued to be roughly kneaded to obtain a magnetic paint.

Various types of crosstalk devices can be used to disperse crosstalk. Examples of this kneading machine include a Miki roll mill, a Miki roll mill, and a ball mill.

Examples include a pebble mill, a sight grinder, a Sqegvari attritor, a high speed impeller disperser, a high speed stone mill, a high speed impact mill, a Disper Kneader-1 high speed mixer, a homogenizer, an ultrasonic disperser, and the like.

The coating solution of the magnetic layer forming component thus prepared is coated onto a non-magnetic support by a known method.

Application methods that can be utilized in this invention include, for example, gravure roll coating, wire bar coating, doctor blade coating, reverse roll coating, dip coating, air knife coating, calendar coating, squeegee coating, kiss coating, and fan coating. Examples include tin coating.

The thickness of the magnetic layer coated in this way is usually 0.5 to 20 gm on a dry basis.

In this way, after applying the magnetic layer forming components, the undried state is
In Step 5, perform magnetic field orientation treatment as necessary, and further,
Surface smoothing treatment is usually performed using a super calender roll or the like.

- Cutting of magnetic recording medium original fabric - In the present invention, it is preferable that the magnetic recording medium original fabric is cut by a cutting device equipped with a shear type rotary blade and a cleaning member for cleaning the shear type rotary blade.

In the present invention, the original magnetic recording medium having a Young's modulus within the above range has less cutting debris, but by cutting with the above-mentioned cutting device, it can be cut with even less generation of cutting debris. Something comes up.

As a specific example of the above-mentioned cutting device, for example, as shown in FIGS. 1 and 2, an I & cutting device fixed blade is provided with an upper blade 1 which is a shear type rotary blade and a lower blade 2 which is a fixed blade. A cutting device having an upper blade l and a lower blade 2 which is a shearing rotary blade,
Alternatively, a cutting device including an upper blade 1 and a lower blade 2, both of which are shearing rotary blades, may be mentioned.

The cleaning member may be, for example, a pair of cleaning members sandwiching a shearing type rotary blade 4 as shown in FIGS. For example, the cleaning member 5 pressed against the cleaning member 4 can be mentioned. Any of the cleaning members can remove deposits from the shearing type rotary blade 4.

A preferred material for the cleaning member 5 is nonwoven fabric.

The thickness of the nonwoven fabric is usually within the range of 0.1 to 5 mm, preferably within the range of 1 to 4 mm.

Furthermore, since the nonwoven fabric is usually worn out by contact with the shearing rotary blade 4, it is preferable to use a material that does not easily generate dust.

When adopting a method of removing deposits from the shearing type rotary blade 4 by pressing the cleaning member 5 against the shearing type rotary blade 4 with a push roll 6 as shown in FIG. 5, as shown in FIG. While taking up the cleaning member 5 with the take-up roll 7, the cleaning member 5 is unwound with the unwinding roll 8, so that the cleaning member 5 is moved and the cleaning member 5 is moved against the shear type rotary blade 4. It is preferable that the contact surface 5a is constantly renewed.

Further, when adopting a method of removing deposits from the shearing type rotary blade 4 by pressing the cleaning member 5 against the shearing type rotary blade 4 with a push roll 6 as shown in FIG.
By using a mesh net for the push roll 6 and evacuating the inside of the push roll 6, the deposits on the shearing type rotary blade 4 can be more thoroughly removed.

Note that the shearing type rotary blade 4 is usually attached to the shearing type rotary blade 4 due to cutting debris from the original magnetic recording medium (cutting debris from the magnetic layer, support, etc.), dust in the atmosphere, etc. This is what I did.

By cutting the magnetic recording medium original fabric in this manner, the original fabric can be cut into a desired shape, and a magnetic recording medium having a desired shape can be manufactured.

The magnetic recording medium produced by the method of the present invention can be used as a magnetic tape such as a video tape or audio tape by cutting it into a long length, or as a floppy disk by cutting it into a disk shape. Furthermore, like ordinary magnetic recording media, it can also be used by being molded into a card shape, cylinder shape, or the like.

[Example] Next, Examples and Comparative Examples of the present invention will be shown to further specifically explain the present invention. In addition, in the examples and comparative examples described below, "parts" shall represent "parts by weight."

(Example 1) A magnetic layer composition having the composition shown below was prepared using a ball mill.
A magnetic paint was prepared by mixing and dispersing.

γ-Fe, 0. Powder・・・・・・α-A Cross 201 ・・・・・・・・・・・Carbon black・・・・・・・ Potassium sulfonate group-containing 100 parts 8 parts 5 parts Vinyl chloride copolymer・・18 Part thermoplastic polyurethane resin 7 parts Butyl stearate Methyl ethyl ketone Toluene Polyisocyanate 1 part 100 parts 100 parts 10 parts The amounts used of each component are γ-Fe, 0 ° Based on 100 parts of powder.

The obtained magnetic coating liquid was rolled to a thickness of 14.5 m using a reverse roll so that the dry thickness after calendering was 4.0 parts m.
It was applied to one side of the polyethylene terephthalate film of Part M, and the solvent was removed under heating.

Next, a surface smoothing process was performed using a super calender, and a curing process was performed at 60°C for 24 hours.
(A magnetic recording medium original fabric of 100 ma was obtained.

The Young's modulus in the width direction of the obtained magnetic recording medium material was measured using a tensile tester [manufactured by TOYOBALDWIN, Model 11].
7M-100], 500 kg/m
*2.

The obtained 3QOOm-wound magnetic recording medium material was rotated at 60°
A curing process was performed for 24 hours at C, and the tape was slit to a predetermined width using a cutting device to create a videotape.

The cutting device used was a cutting device equipped with an upper blade and a lower blade, both of which were shearing rotary blades.

A 500 ILm thick layer 5 was provided on the upper blade as shown in FIG. 5 to remove dust etc. attached to the upper blade, and the nonwoven fabric 5 was pressed against the upper blade with an extrusion roll 6 to perform cutting.

Note that the inside of the extrusion roll 6 was not evacuated.

Next, various characteristics of the produced videotape were measured.

In addition, each characteristic was measured as follows.

Dropout: ■ Measured using a TR dropout counter (manufactured by Shihasoku).

Head clogging: Recording and playback were performed over the entire length of the tape, and the presence or absence of a decrease in RF-OUT due to head clogging was examined and evaluated on the following five scales.

◎: The RF-OUT drop is less than 0.5 dB, and the head is not contaminated.

○: RF-OUT decrease is 1.0 dB or less.

There is almost no dirt on the head.

△: l? The F-0υ decrease is less than 2.0dB, and there is some dirt on the head.

x x: RF-OUT drop is 2.0dB or more.

The head is very dirty.

The results are shown in the r51 table.

(Examples 2 to 5 and Comparative Examples 1 to 6) The presence or absence of the nonwoven fabric 5 on the upper blade, the presence or absence of the nonwoven fabric 5 on the lower blade, and the Young's modulus of the raw magnetic recording medium to be cut were Two characteristics of the produced videotape were measured and evaluated in the same manner as in Example 1, except that the procedure was as shown in Table 1.

The results are shown in Table 1.

(Wood page, blank space below) (Evaluation) As is clear from Table 1, the magnetic recording medium manufactured by the method of the present invention has excellent performance with fewer dropouts and no clogging of the magnetic head. 'It has electromagnetic conversion characteristics.

[Effects of the Invention] According to the method of the present invention, (1) it is possible to prevent adhesion of cut residue etc. to the manufactured magnetic recording medium, and (2) it is possible to reduce dropouts and improve the magnetic head. It is possible to provide a method for manufacturing a magnetic recording medium that has the following advantages, such as having excellent electromagnetic conversion characteristics without causing clogging.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment in which a shearing type rotary blade is provided in a cutting device. FIG. 2 is a cross-sectional view showing an embodiment in which a cutting device is provided with a shearing rotary blade. FIG. 3 is an explanatory diagram showing an embodiment in which a cleaning member is provided on the shearing type rotary blade. FIG. 4 is a sectional view showing an embodiment in which a shearing type rotary blade is provided with a cleaning member. FIG. 5 is an explanatory diagram showing an embodiment in which a cleaning member is provided on the shearing type rotary blade. Figure 6 shows
It is an explanatory view showing a mode in which a cleaning member is pressed against a shear type rotary blade with a push roll. DESCRIPTION OF SYMBOLS 1... Upper blade, 2... Lower blade, 3... Magnetic recording medium original fabric, 4... Shear type rotary blade, 5... Cleaning member.

Claims (2)

[Claims] (1) The Young's modulus in the width direction is 400 to 800 kg/mm^ while removing the deposits on the shear type rotary blade with a cleaning member.
2. A method for manufacturing a magnetic recording medium, which comprises cutting an original magnetic recording medium according to item 2. (2) the shearing type rotary blade consists of a pair of upper blade and lower blade;
2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the cleaning member is pressed against the upper blade and/or the lower blade.