JPH01102735A - Manufacture of magnetic recording medium and smoother used in the same - Google Patents

Abstract

PURPOSE:To effectively prevent the cutting powder of a nonmagnetic supporting body raw sheet, etc., from being generated and to prevent an electromagnetic conversion characteristic and traveling durability from being lowered by performing the smoothing of a coating layer by making the coating layer of a magnetic coating material bring into contact with a smoother under a state where the noncoating part of the magnetic coating material is not brought into contact with the smoother. CONSTITUTION:The horizontal cross-section of the smoother 1 in a length direction is formed in circular arc or linear shape, or the combined shape of them, and a corner is provided at the terminating part 6a of a contact plane. Therefore, it is possible to smooth the surface of the coating layer 4 by making the sector arc part 2 of the smoother 1 bring into contact with the coating layer 4 of the coating material applied on the nonmagnetic supporting body raw sheet 3. Also, by notching the terminating parts 6a and 6b in a direction upper than the contact part with the coating layer, it is possible to evade the contact of the nonmagnetic supporting body raw sheet 3 with the noncoating parts 5a and 5b. In such a way, it is possible to prevent the cutting power from being generated effectively.

Description

[Detailed description of the invention] [Industrial application field].

The present invention relates to a method for manufacturing a magnetic recording medium that can effectively prevent instantaneous drop or dropout of reproduced signals, and a novel smoother used in this method. ] Magnetic recording media are generally made by applying magnetic paint to a long non-magnetic support material, leaving uncoated areas at the edges in the width direction.
After performing necessary treatments such as magnetic field orientation treatment, the coated layer of magnetic paint is dried, and then surface smoothing treatment such as calender treatment is performed.

Then, it is manufactured by cutting it into a desired shape.

Furthermore, in order to prevent the reproduction signal from decreasing due to spacing loss between the magnetic layer and the magnetic head, after applying the magnetic paint, the surface of the applied layer is brought into contact with a smoother while the applied layer is not dry. A method is used to smooth the surface of the layer.

However, it has been found that when a smoother is used, instantaneous drop or dropout of the reproduced signal of the magnetic recording medium may increase. This phenomenon occurs when a magnetic material obtained by cutting a non-magnetic support material coated with magnetic paint (material material for magnetic recording media) within several tens of centimeters from the edge in the width direction. Often seen in recording media.

As a result of investigating the cause of such a phenomenon, the inventor of the present invention found that when smoothing a coated layer of magnetic paint, the non-coated portion of the widthwise edge of a long non-magnetic support material and the smoother When the non-magnetic support comes into contact with Furthermore, the adhesion of shavings to the surface of the calender roll used in the subsequent surface smoothing process forms recesses in the magnetic layer, which is an indirect cause of instantaneous drop or dropout of the reproduced signal. It turned out to be.

The present invention effectively prevents the generation of shavings of the original non-magnetic support material generated by using a smoother. Another object of the present invention is to provide a method for manufacturing a magnetic recording medium that can effectively prevent a decrease in running durability.

[Means for solving the above-mentioned problems] The first configuration of the present invention is to apply a magnetic coating material to the widthwise edge of a long non-magnetic support material, leaving an uncoated portion; In a method for producing a magnetic recording medium in which a coated layer of magnetic paint is brought into contact with a smoother, the coated layer of magnetic paint is brought into contact with a smoother without contact between the non-coated portion of the magnetic paint and the smoother. This is a method for producing a magnetic recording medium characterized by smoothing the surface of the magnetic recording medium.

The method for manufacturing the magnetic recording medium described above is such that the coating is applied onto a non-magnetic support material in a smoother made of a long inflexible material that is longer than the width of the long non-magnetic support material. A contact portion that contacts the surface of the magnetic coating layer to smooth it, and a contact portion at both ends of the contact portion.

Continuous cuts are made from the contact part in a direction above the virtual contact line from the contact part, which is provided at a position corresponding to the non-applied part of the magnetic paint at the edge in the width direction of the original support. This can be advantageously carried out by using a smoother characterized by having a non-contact part.

The method for manufacturing the magnetic recording medium of the present invention is basically as follows.

Edges in the width direction of the long non-magnetic support material and the smoother
This effectively prevents the shavings generated by contact with the magnetic paint from adhering to the coated layer of magnetic paint and the back surface of the non-magnetic support material.

In the method for producing a magnetic recording medium of the present invention, first, a magnetic paint is applied to the edges of a long non-magnetic support material in the width direction, leaving uncoated portions.

-Non-magnetic support material- In the method for producing the magnetic recording medium of the present invention, ordinary non-magnetic support material can be used as the elongated non-magnetic support material.0Non-magnetic support used in the present invention Examples of materials forming the raw fabric include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose triacetate, and plastics such as polycarbonate. be able to.

The thickness of the nonmagnetic support fabric formed using these materials is usually within the range of 3 to 1100B.

A back coat layer can also be provided on the back surface of the original nonmagnetic support for the purpose of improving running performance.

In addition, an intermediate layer (e.g., adhesive layer, undercoat layer) is provided between the non-magnetic support material and the magnetic layer for the purpose of improving the adhesion between the magnetic layer and the non-magnetic support material. You can also do that.

The raw non-magnetic support used in the production method of the present invention is a long one, and usually such a long raw non-magnetic support is run continuously. A magnetic recording medium material is manufactured by applying magnetic paint to the opposite surface and contacting it with a smoother, and then undergoing steps such as magnetic field orientation treatment and surface smoothing treatment. A magnetic recording medium can be obtained by cutting into a shape.

1. Magnetic Paint 1. A magnetic paint to be coated on a non-magnetic support material is basically one in which magnetic layer forming components including magnetic powder and 1 resin binder component are dispersed in an organic solvent.

Magnetic Powder There are no particular restrictions on the magnetic powder used in the method for producing the magnetic recording medium of the present invention, and any magnetic powder that can be used in ordinary magnetic recording media can be used.

Examples of magnetic powders that can be used in the present invention include iron oxide magnetic powders (e.g., y-Fe2O, Fe303), G
Oxide-based magnetic powder containing other components such as o (e.g.
Go-containing oxide, iron), Ba ferrite, Fe,
Ni.

Ferromagnetic alloy powder containing a ferromagnetic metal such as CO and other components (eg, Fe-Al1 alloy powder, Fe-Al-Ni alloy powder, Fe-Ni-Co alloy powder, Fe-Mn-Zn alloy powder).

Fe-Ni-Zn alloy powder, Fe-Go-Ni-Cr
Alloy powder, Fe-Go-Ni-P alloy powder, Co-N
i alloy powder, Fe-An-C, o alloy powder, Fe-N1
-Go-Al1 alloy powder and 7Co-P alloy powder) and ferromagnetic bonds (e.g. Fe.

A fine ferromagnetic metal powder consisting of Ni and Co) can be mentioned.

There is no particular restriction on the shape of the magnetic powder that can be used in the present invention, and for example, needle-like, spherical, ellipsoidal, or plate-like shapes can be used.

(1) Resin component (1) As the resin binder component that forms the magnetic paint together with the above-mentioned magnetic powder, resin components such as thermoplastic resin, thermosetting resin, reactive resin 3, and electron beam curable resin can be mentioned. Furthermore, these resins and a curing agent can also be used together.

As the thermoplastic resin, those having a softening temperature of 150 DEG C. or lower, an average molecular weight of 10,000 to ZO 0,000, and a degree of polymerization of 100 to 2,000 can be used. Examples of such thermoplastic resins include:
Vinyl chloride copolymers, acrylic acid copolymers, cellulose derivatives, urethane elastomers, polyvinyl fluoride resins, vinylidene chloride-acrylonitrile copolymers, acrylonitrile-butadiene copolymers, polyamide resins, polyvinyl butyral Examples include copolymers, styrene-butadiene copolymers, polyester resins, chlorovinyl ether-acrylic acid ester copolymers, amino resins, and synthetic rubber thermoplastic resins.

The thermosetting resin or reactive resin has a molecular weight within the range of 10,000 to 200,000 in the magnetic paint, and after coating and drying, it becomes a cured resin with an infinite molecular weight through condensation reaction, addition reaction, etc. Preferably.

These resin cured products include, for example, combinations of polyurethane resins, phenoxy resins, and curing agents, combinations of high molecular weight polyester resins and cured products, combinations of methacrylate copolymers and cured products, and combinations of polyester polyols and cured products. and combinations of low molecular weight glycols, high molecular weight diols, and cured products, phenolic resins, epoxy resins, polyurethane curing resins, urea resins, melamine resins, alkyra resins, de resins, silicone resins, acrylic reaction resins, etc. It can be obtained by curing a self-curing resin, a cured urea formaldehyde resin, and a polyamine resin.

Examples of electron beam irradiation-curable resins include non-dispersible prepolymers and polyfunctional polymers.

These resins can be used alone or in combination. Furthermore, in addition to the resin component, a curing agent such as a polyisocyanate compound can also be used in combination.

The mixing ratio of the magnetic powder and the resin binder component (including the curing agent if a curing agent is used) in the magnetic paint is determined by considering both electromagnetic conversion characteristics and running durability.
The amount is usually set within a range of 5 to 400 parts by weight per 100 parts by weight of magnetic powder.

-Solvent for Preparing Magnetic Paint- The solvent used in preparing the magnetic paint can be appropriately selected in consideration of solubility in the resin, dispersibility in magnetic powder, etc., removability, economic efficiency, and the like. Examples of such solvents include: ketonic solvents such as methyl ethyl ketone (ME), methyl isobutyl ketone (MIBK) and cyclohexanone; alcoholic solvents such as methanol, ethanol, propatool and butanol; methyl acetate, ethyl acetate, acetic acid. Ester solvents such as butyl, propyl acetate and ethylene glycol heptanoacetate
Ether solvents such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, and dioxane; aromatic solvents such as benzene, toluene, and xylene; and methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and dioxane. Examples include halogenated hydrocarbon solvents such as chlorobenzene. In the present invention, the solvents can be used alone or in combination.

-Other components- In addition to the above-mentioned magnetic powder and resin binder components, the magnetic paint contains components contained in the magnetic layer of ordinary magnetic recording media, such as abrasives, antistatic agents, and lubricants. can do.

Examples of abrasives that can be used in the present invention include organic powders with a Mohs hardness of 5 or higher (e.g., benzoguanamine resin powder, melamine resin powder, and phthalocyanine compound powder) or inorganic powders (e.g., α-alumina, oxidized titanium, silicon oxide, silicon nitride, chromium oxide and boron carbide). These abrasives can be used alone or in combination, and the average particle size of these abrasives is usually in the range of 0.05 to 2.0 gm.

Further, the blending amount of these abrasives is usually within the range of 0.5 to 20 parts by weight per 100 parts by weight of the magnetic powder.

Examples of antistatic agents that can be used in the present invention include conductive powders (e.g., graphite, carbon black,
Tin oxide (titanium oxide) ~ antimony oxide compound, carbon black graft polymer), natural surfactant (
Mention may be made, for example, of saponins), nonionic surfactants, higher alkylamines, cationic surfactants, anionic surfactants and amphoteric surfactants. These antistatic agents can be used alone or in combination.

The blending amount of the antistatic agent is based on 100 parts by weight of magnetic powder.
It is usually within the range of 0.5 to zQffi parts.

As the lubricant to be mixed into the magnetic paint, those used as lubricants for ordinary magnetic recording media can be used. Examples of such lubricants include fatty acid esters, fatty acids, silicon compounds, modified lubricants, etc. Silicon compounds (e.g.
ester-modified silicon compounds, fluorine-modified silicon compounds), liquid paraffins, mineral oils and solid lubricants (e.g. carbon black, graphite, carbon black graft polymers, molybdenum disulfide and tungsten disulfide), which alone Or they can be used in combination.

The amount of lubricant to be blended is usually in the range of 1 to 15% by weight based on 100 parts by weight of the magnetic powder. Note that lubricants other than the solid lubricant may be dissolved in an organic solvent and applied onto the magnetic layer without being blended into the magnetic paint.

In the present invention, the abrasive, lubricant, antistatic agent, dispersant, etc. described below do not have a sole function, and for example, the component (-) may act as a lubricant and an antistatic agent. be. Therefore, the above-mentioned classification according to the present invention shows the main effects, and the effects of the classified compounds are not limited by the effects shown in the classification.

1. Kneading and dispersing method - The kneading and dispersing method of the magnetic layer type r#J component containing the above components can be carried out by a conventional method.

When mixing and dispersing the magnetic paint components, there is no particular restriction on the order in which the magnetic paint components are added, and the mixing and dispersion can be carried out by adding each component according to a conventional method. However, if a curing agent is used, it is preferable to add the curing agent immediately before applying the magnetic paint in order to prevent the curing reaction from proceeding due to the curing agent during crosstalk and dispersion.

A known cross-dispersion device can be used for cross-mixing and dispersion, and examples of such kneading and dispersion devices include a two-roll mill, a Miki roll mill, a ball mill, a pebble mill, a sand grinder, Sqegv
Mention may be made of the ari attritor, high speed impeller disperser, high speed stone mill, high speed impact mill, Disper Kneader-1 high speed mixer, homogenizer and ultrasonic disperser.

When kneading and dispersing, use 1 dispersant (e.g. fatty acids, lecithin,
Phosphate ester, amine compound, alkyl sulfate,
Fatty acid amide, higher alcohol, polyethylene oxide, sulfosuccinic acid, sulfosuccinic acid ester, surfactant showing a dispersing effect, and polymer-based dispersant containing a negative organic group
It is usually added within the range of 1 to 20 parts by weight relative to 0 parts by weight.

1. Coating method 1. Apply the thus prepared magnetic paint onto a long non-magnetic support material by a known method, leaving an uncoated portion at the edge in the width direction of the long non-magnetic support material. . The width of the non-coated portion at this time is usually within the range of 1 to 10 cm.

Examples of application methods that can be utilized in the present invention include 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. One example is tin coating.

The wet film thickness of the magnetic paint applied in this manner is usually within the range of 1 to 40 pm.

-Smoother- After applying the magnetic paint onto the original non-magnetic support,
The applied layer of magnetic paint is still wet.

Smooth the surface of the coating layer by passing it through a smoother.

The smoother used in the present invention is usually a long non-flexible body (eg, metal, hard plastic, ceramic).
Consisting of

FIG. 1 shows an example of processing using a smoother used in the present invention.

In FIG. 1, the smoother is designated l. Normally, a smoother is used to make the surface of the applied layer of magnetic paint smoother, so the cross section of the contact surface in the length direction of the smoother is arcuate, linear, or a combination thereof. The end of the contact surface has a corner. FIG. 1 shows a smoother with a fan-shaped cross section.

The fan-shaped arc portion (contact portion) 2 of the smoother 1 contacts the coated layer 4 of the magnetic paint coated on the elongated non-magnetic support material 3, thereby coating the surface of the coated layer 4. smooth.

FIG. 2(a) is a partially enlarged sectional view of the end portion 6b of the smoother shown in FIG. 1.

As shown in FIG. 2(a), the smoother used in the present invention smoothes a portion corresponding to the non-applied portion 25b.
The cut is made upward from the virtual contact line from the contact portion 22 (indicated by a broken line in FIG. 2(A)). By doing this, the non-magnetic support material 2
Contact with the non-applied portion 25b of No. 3 can be avoided,
Generation of shavings can be effectively prevented.

The upward cut 27 needs to be cut continuously upward from the virtual contact line, for example, the cut 27 in the coating layer 2
If the notch is formed by providing a step from 4, the non-magnetic support material 23 will be damaged by etching at the one step difference and shavings will be generated, making it impossible to achieve the object of the present invention.

In the present invention, in order to effectively prevent the generation of cutting powder, it is preferable that the cutting angle (θ) is set to 1 degree or more with respect to the virtual contact line. Further, by setting θ within the range of 3 to 45 degrees, the generation of cutting powder due to contact is particularly reduced. θ
If it is less than 1 degree, it may not be possible to effectively avoid contact with the non-magnetic support, and if it is more than 45 degrees, the angle formed by the contact part 22 and the non-contact part 27 and the non-magnetic support may not be effectively avoided. Grinding powder may be generated due to contact with the support material 23.

In addition, the smoother of the present invention may have any shape as long as it does not come into contact with the non-contact portion of the original non-magnetic support. It is also possible to cut one end of the smoother upward in an arc shape.

That is, in FIG. 3(a), the nonmagnetic support is 3
3, and the applied layer of magnetic paint is shown as 34.

An arcuate notch 37 is formed at the end of the smoother 31. In addition, when forming a circular arc-shaped cut, it is preferable to set the radius of the circular arc of the cut within the range of 10 to 100100 mm, particularly preferably 20 to 100 mm.

In this way, by providing a non-contact part at one end of the smoother so that the end of the smoother does not come into contact with the non-applying part,
The generation of cutting powder can be effectively prevented, and therefore the occurrence of instantaneous drop or omission of the reproduced signal such as dropout can be reduced.

In addition, in the present invention, the smoother of the present invention is applied while dropping an organic solvent such as toluene onto the area where the magnetic paint is not applied.
It is also possible to place a suction removal device for the shavings near the smoother. By doing so, even if the non-contact portion of the smoother comes into contact with the non-magnetic support, scattering of cutting powder can be effectively prevented.

-Other processes- After smoothing the surface of the coating layer using a smoother in this way, when manufacturing tape-shaped magnetic recording media such as video tapes and audio tapes, the magnetic paint is left undried. In addition, when producing a disc-shaped magnetic recording medium such as a Tulotsby disk, a non-orientation process is performed, and the coating layer is dried in a dryer zone to form the magnetic layer. Form.

Next, a surface smoothing treatment is usually performed using a calender roll or the like.

The magnetic recording medium material obtained in this manner is cut into a desired shape such as a tape shape or a disk shape.

[Example] In the Examples and Comparative Examples described below, the expression "parts" represents "parts by weight."

(Example 1) The following magnetic paint component [I] was mixed with cyclohexanone,
Using a mixed solvent of toluene and methyl ethyl ketone (mixing volume ratio = 4:3:3) as a solvent, the mixture was thoroughly kneaded and dispersed using a disper kneader and a ball mill, and then,
Immediately before application, apply a polyisocyanate compound (coronate,
5 parts of Nippon Polyurethane Co., Ltd.) were added and mixed to prepare a magnetic paint.

! ■ Ferromagnetic alloy powder・・・・・・・・・・・・・・・・・・
......100 parts (aluminum content: 3.5
Weight% Specific surface area: 5Otn'/g - Coercive force (Hc): 14500e) Polyurethane resin・・・・・・・・・・・・・・・・・・
・・・・・・・・・5 parts: Tuboran 2304, made by Nippon Polyurethane) Phenoxy resin・・・・・・・・・・・・
・・・・・・・・・・・・・・・8 parts (PKHH: manufactured by U.S.A., U.C., Inc.) α-alumina・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・7 parts carbon black・・・・・・・・・・・・・・・・・・・・・
...1 part particle size: 50ml Specific surface Q: 30rn'/g Butyl stearate...
After filtering 3 parts of the obtained magnetic paint, apply this magnetic paint to one side of the original polyethylene terephthalate film support (thickness: 10 pm) for 5 m on both sides.
The coating was continued using a reverse roll coater so that the wet film thickness was 201L711, leaving an uncoated portion of m.

Next, a smoother whose cross-sectional shape shown in FIG. 2 (b) is a fan shape with a radius of 35 mm and a center angle of 90 degrees, and the non-contact part is cut linearly at an angle (θ) of 5 degrees with respect to the virtual contactability. −
The coated layer of magnetic paint was smoothed using a .

After smoothing, the material was passed through a dryer zone for dry blasting, and then calendered to obtain an original magnetic recording medium.

This magnetic recording medium material was slit into a width of 8 mm.
8mm video tape was manufactured.

Of the obtained videotape, the videotape obtained by slitting the original magnetic recording medium within 5 cm from the non-coated part was loaded into a video deck for dropout measurement modified from a reprinted 8mm video cheap recorder. The number of dropouts was measured.

The number of dropouts occurring per minute of videotape running was 85.

Note that the recorded image signal is 100% white.

The measured dropout has a length of 5 #L seconds or more and a drop in reproduction output of 112 dB or more.

(Comparative Example 1) An 8 mm video tape was prepared in the same manner as in Example 1, except that smoothing was carried out by using a smoother that did not have a cut for the virtual contact line and bringing the non-applied area into contact with the smoother. was manufactured, and the number of dropouts was measured in the same manner.

The number of dropouts occurring per minute of videotape running was 253.

(Example 2) In Example 1, except that a smoother cut in a straight line at an angle (θ) of 20 degrees with respect to the non-contact part or the virtual contact line shown in FIG. 2 (A) was used. An 8 mm video tape was produced in the same manner, and the number of dropouts was measured in the same manner.

The number of dropouts occurring per minute of videotape running was 72.

(Example 3) An 8 mm video tape was manufactured in the same manner as in Example 1, except that a smoother cut in an arc shape with a radius of 100 mm was used in the non-contact portion shown in FIG. 3 (A). The number of dropouts was measured in the same manner.

The number of dropouts occurring per minute of videotape running was 78.

[Effects of the Invention] According to the method for producing a magnetic recording medium of the present invention, the part where the magnetic paint is not applied does not come into contact with the smoother, so the non-magnetic support material in this part is not scraped off. Therefore, it is possible to effectively prevent instantaneous drop and dropout of the reproduction signal due to adhesion of cutting powder to the surface of the magnetic coating layer. In addition, since cutting powder does not adhere to the surface of the calender roll, no recesses are formed on the surface of the magnetic layer during the surface smoothing process, which effectively prevents instantaneous drops and omissions in indirect playback signals. It can be prevented.

In this way, the magnetic recording medium of the present invention can reduce the playback signal by reducing the
Electromagnetic conversion characteristics as there are fewer missing parts.

Various properties such as running durability are always at a stable level.

Further, since cutting powder does not adhere to the surface of the magnetic layer, there is an advantage that clogging of the magnetic head is less likely to occur.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of surface smoothing of a coated layer of magnetic paint using a smoother. FIG. 2(a) is a partially enlarged sectional view of the end portion of the smoother of the present invention, and FIG. 2(b) is an explanatory view showing the same cross-sectional shape. FIG. 3(A) is a partially enlarged sectional view of the end portion of a smoother according to another embodiment of the present invention, and FIG. 3(B) is an explanatory view showing the same cross-sectional shape. 1, 21.31--Smoother 12, 22--Smoother's fan-shaped arc part (contact part), 3, 2
3.33--Elongated non-magnetic support material, 4, 24
．． 34-...Magnetic paint coating layer, 5a, 5b, 25b
. . . Non-applied portion, 27b, 37b --- Non-contact portion. 1st [-1

Claims (4)

[Claims] (1) In a method for manufacturing a magnetic recording medium in which a magnetic paint is applied to a long non-magnetic support material, leaving an uncoated area at the edge in the width direction, and then the coated layer of magnetic paint is brought into contact with a smoother. . A method for producing a magnetic recording medium, which comprises smoothing the coated layer by bringing the coated layer of magnetic paint into contact with a smoother without contacting the area to which the magnetic paint is not coated with the smoother. (2) In a smoother made of an elongated non-flexible material that is longer than the width of the elongated non-magnetic support material, the surface of the coating layer of magnetic paint applied on the non-magnetic support material material is a contact portion that contacts and smoothes the surface; and a contact portion provided at both ends of the contact portion that corresponds to the non-applied portion of the magnetic paint at the edge in the width direction of the original support. 1. A smoother comprising: a non-contact portion continuously cut from a contact portion above a virtual contact line from the contact portion; (3) The non-contact portion of the smoother is continuously cut straight upward from the contact portion at an angle of 1 degree or more with respect to the virtual contact line at the edge of the magnetic layer. The smoother according to item 2. (4) According to claim 2, the non-contact portion of the smoother is continuously cut in an arc shape from the contact point of the edge of the magnetic layer upward from the contact portion with respect to the virtual contact line. smoother.