JPS61289531A - Non-orientation treatment of magnetic recording medium and apparatus for producing magnetic recording medium - Google Patents

Abstract

PURPOSE:To permit the effective non-orientation of magnetic particles by forming one orienting magnetic field as the orienting magnetic field in the direction intersecting with the moving direction of a base and forming the other orienting magnetic field as the orienting magnetic field in the moving direction of the base and/or the direction opposite therefrom. CONSTITUTION:The base 1 is conveyed to a magnetic paint coating means 3 and a coated film contg. magnetic particles is formed thereon. The magnetic particles in the coated film are oriented in the direction intersecting with a conveying direction 8 while the base passes the 1st orienting magnetic field 4. The orientation of the magnetic particles mechanically oriented in the direction parallel with the direction 8 in the coating means 3 is thus negated. The magnetic particles in the coated film move in the coated film so as to be oriented in the direction 8 and/or the direction opposite therefrom during the time when the base 1 passes the 2nd orienting magnetic field 5 but the base 1 enters a drying means 6 before the particles are oriented in said direction. The coated film is dried by such means and the movement of the magnetic particles stops and therefore the directions of the magnetic particles are made random and not oriented. The movement of the magnetic particles is thereby made easy and the resulted magnetic recording medium has the high non-orientation.

Description

[Detailed description of the invention] Regarding location.

BACKGROUND OF THE INVENTION Magnetic recording media are widely used as magnetic tapes for audio and other recording purposes, magnetic recording tapes for VTRs, magnetic disks for computers, word processors, and the like. Since a magnetic tape for a VTR comes into sliding contact obliquely with a magnetic head at a predetermined angle, it would be inconvenient if the magnetic particles in the magnetic layer were oriented only in the longitudinal direction of the tape. The presence of magnetic particles is required. Additionally, magnetic disks require the presence of circumferentially oriented magnetic particles.

In recent years, it has become possible to increase the density of magnetic particles in a magnetic layer, making it possible to randomly orient the magnetic particles to make them non-oriented and increase the number of magnetic particles oriented in a predetermined direction as described above. ing. Therefore, attempts have been made to improve productivity by cutting magnetic tapes and magnetic disks from long non-oriented magnetic recording media. Such an attempt is
In particular, this leads to a significant improvement in the productivity of magnetic disk manufacturing.

For example, the following method has been proposed as a method for making a magnetic recording medium non-oriented.

(i) A method in which magnetic particles are oriented in the direction of application of magnetic paint by a first oriented magnetic field, and then non-oriented by a weak second oriented magnetic field in the opposite direction to the first oriented magnetic field ( JP-A-53-104206) (11) A method in which magnetic particles are oriented in the direction of application of magnetic paint by a first oriented magnetic field, and then rendered non-oriented by a plurality of oriented magnetic fields weaker than the first oriented magnetic field ( (Japanese Unexamined Patent Publication No. 149607/1983).

(iii) 5 (11 or more magnets are arranged on the coated side or the anti-coated side of the magnetic paint with alternately different polarities and gradually decrease in the transport direction of the support, and the magnetic lines of force adjacent to each other are substantially A method of continuous non-orientation (JP-A-59-124039).

(iv) alternating directions (preferably +45°, −
(at an angle of 45°) and a method of non-orientation using a gradually decreasing magnetic field in the opposite direction (Japanese Unexamined Patent Publication No. 159204/1984).

(V) A method of dividing and arranging bar magnets in the width direction at an angle of 5 to 45 degrees with respect to the direction in which the magnetic paint is applied (Japanese Unexamined Patent Publication No. 59-42644) (vi) Magnetic field in the axial direction A method of non-orientation using an orientation roller that follows the
Japanese Patent Application Publication No. 57-189344! (vi) A non-oriented method by arranging a large number of magnets with alternating N and S poles so as to form a magnetic field perpendicular to the conveying direction of the coated web (JP-A-59-148140) Public bulletin).

(vii) A method in which magnets are arranged alternately with N and S poles so as to form a magnetic field perpendicular to the direction in which the magnetic paint is applied (Japanese Unexamined Patent Publication No. 148140/1982).

However, the above conventional method has the following problems.

In the methods (i) to (iii), it is necessary to set the magnetic field strength in a predetermined pattern, which results in poor reproducibility in measurements and settings, and is unstable in terms of operational and production stability.

The methods (iv) and (v) lack versatility for different magnetic particles, and in particular, the method (iv) produces a non-oriented assembly in which the directions alternate and gradually decrease when the directions are reversed. It is difficult to

Methods (vi), (vi), and (vii) require the use of special rollers or a large number of magnets and solenoids, and are difficult to employ as practical devices.

C. Purpose of the Invention The present invention has been made in view of the above circumstances, and includes:
It is an object of the present invention to provide a method for processing a magnetic recording medium to make magnetic particles effectively non-oriented using a simple device, and an apparatus for manufacturing the same.

D. Purpose of the Invention The first aspect of the present invention is to form a layer containing magnetic particles on a support, pass the support sequentially through a plurality of orienting magnetic fields, and apply one of the plurality of orienting magnetic fields. is an orientation magnetic field in a direction that intersects the moving direction of the support,
The present invention relates to a method for making a magnetic recording medium non-oriented, wherein the other oriented magnetic field is an oriented magnetic field in the moving direction of the support and/or in the opposite direction.

A second aspect of the present invention provides a means for forming a layer containing magnetic particles on a support; an orienting magnetic field in a direction crossing the moving direction of the support; a plurality of orienting magnetic fields in opposite directions; and a drying means for drying the layer, and a portion of the latter part of the plurality of orienting magnetic fields is located in the drying means. related to manufacturing equipment.

1-place □□□j・ E, Example Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 shows an outline of the apparatus, in which a support 1 wound around a supply roll 2 is conveyed to a magnetic coating coating means 3, where a coating film containing magnetic particles is formed, and a first orientation magnetic field 4 and a coating film containing magnetic particles are formed. The magnetic particles in the coating film are passed through a second orientation magnetic field 5 (the contents of which will be explained in detail later) to become non-oriented, and then passed through a drying means 6 to dry the coating film and form a magnetic layer. The sheet is then guided to a calender section 7 consisting of a combination of calender rolls 7a, subjected to calendering, and wound onto a winding roll 22. The thus manufactured magnetic recording medium is subjected to the next slinting process or punching process (not shown) into a disk shape. In the figure, 3a is an opposing roll for coating, 3b
is a blade that scrapes off excess paint, and 3C is a magnetic paint.

In magnetic recording media, at least polyurethane can be used as a binder resin for the magnetic layer, which can be synthesized by reacting a polyol with a polyisocyanate. Usable polyols include organic dibasic acids such as phthalic acid, adipic acid, trimerized lyluic acid, and maleic acid, and glycols such as ethylene glycol, propylene glycol, butylene glycol, and diethylene glycol, or trimethylolpropane, hexanetriol, and glycerin. , polyester polyol synthesized by reaction with polyhydric alcohols such as trimethylolethane, pentaerythritol, or any two or more polyols selected from these glycols and polyhydric alcohols; or S- Caprolactam, alpha
- Lactone polyester polyols synthesized from lactams such as methyl-1-caprolactam, S-methyl-3-caprolactam, and γ-butyrolactam; or polyether polyols synthesized from ethylene oxide, propylene oxide, butylene oxide, etc. Can be mentioned.

These polyols are reacted with isocyanate compounds such as tolylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, metaxylylene diisocyanate, etc., resulting in urethanized polyester polyurethane, polyether polyurethane, and polycarbonate carbonated with phosgene or diphenyl carbonate. Polyurethane is synthesized. These polyurethanes are usually produced primarily by the reaction of polyisocyanates and polyols and are also in the form of urethane resins or urethane prepolymers containing free isocyanate groups and/or hydroxyl groups, or containing reactive end groups of these. It may be in the form of a urethane elastomer, for example.

Since the methods for producing polyurethane, urethane prepolymers, urethane elastomers, curing and crosslinking methods, etc. are well known, detailed explanation thereof will be omitted.

In addition, if a phenoxy resin and/or a vinyl chloride copolymer is also included as a binder resin in addition to the above-mentioned polyurethane, the dispersibility of the magnetic powder will be improved when it is used in a magnetic layer, and its mechanical strength will be increased. . However, if only the phenoxy resin and/or the vinyl chloride copolymer is used, the layer becomes too hard, but this can be prevented by containing polyurethane, and the adhesion to the support or base layer is improved.

The phenoxy resin that can be used is a polymer obtained by polymerizing bisphenol A and epichlorohydrin, and is represented by the following general formula.

(However, n': i82 to 13) For example, PKHClPKHH manufactured by Union Carbide
, PKHT, etc.

Moreover, as the above-mentioned vinyl chloride copolymers that can be used, there are those represented by the following formulas. In this case, in ! The molar ratio derived from and m is 95 to 50 mol % for the former unit and 5 to 50 mol % for the latter unit 7. In addition, X represents a monomer residue that can be copolymerized with vinyl chloride, vinyl acetate,
The degree of polymerization expressed as (l+m) is preferably 100 to 600, and if the degree of polymerization is less than 100, the magnetic layer etc. tends to become sticky,
When it exceeds 600, dispersibility deteriorates. The vinyl chloride copolymer described above is preferably a copolymer containing vinyl chloride-vinyl acetate (hereinafter referred to as "vinyl chloride-vinyl acetate"), which may be partially hydrolyzed. ``vinyl copolymers''). Examples of vinyl chloride-vinyl acetate copolymers include vinyl chloride-vinyl acetate copolymers.
Examples include vinyl acetate-vinyl alcohol and vinyl chloride-vinyl acetate-maleic anhydride copolymers, and among the vinyl chloride-vinyl acetate copolymers, partially hydrolyzed copolymers are preferred. Specific examples of the above-mentioned vinyl chloride-vinyl acetate copolymers include (7) rVAGHJ, rVYHHJ, rVMCHJ manufactured by Union Carbide, and "S-Refuku A" and "S-Resoku A-5" manufactured by Block Chemical Co., Ltd.
, "Suresoku C", "Slesoku M", "Denkabinir 1000GJ", "Denkabinir 1" manufactured by Denki Kagaku Kogyo Co., Ltd.
00OWJ etc. can be used.

In addition to the above, cellulose resins can be used as the binder resin, such as cellulose ethers, cellulose inorganic acid esters, cellulose organic acid esters, and the like. As the cellulose ether, methyl cellulose, ethyl cellulose, etc. can be used. As the cellulose inorganic acid ester, nitrocellulose, cellulose sulfate, cellulose phosphate, etc. can be used. Also,
('/L/te+-S As the organic acid ester, acetyl cellulose, propionyl cellulose, butyryl cellulose, etc. can be used. Among these cellulose resins, nitrocellulose is preferable.

Regarding the entire binder composition, the ratio of the above-mentioned urethane resin to other resins (total amount of phenoxy resin, vinyl chloride copolymer, etc.) is 90/1 in MI ratio.
Desirably 0 to 40/60, 85/15 to 45
155 has been found to be even more desirable. If the amount of urethane resin is outside this range, dispersion tends to be poor.
Also, if there is a large amount of other resins, surface properties tend to be poor.
In particular, if it exceeds 60% by weight, the physical properties of the coating film become less favorable overall. In the case of vinyl chloride-vinyl acetate,
It can be mixed with the urethane resin with a considerable degree of freedom, and preferably the urethane resin is 15 to 75% by weight.

As the binder resin for the layer constituting the magnetic recording medium,
In addition to those mentioned above, thermoplastic resins, thermosetting resins, reactive resins, and electron beam curable resins may be used.

The thermoplastic resin has a softening temperature of 150°C or less, an average molecular weight of 10,000 to 200,000, and a degree of polymerization of about 2.
For example, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, and acrylic ester-styrene copolymer are used.

The thermosetting resin or reactive resin has a molecular weight of 200,000 or less in the state of a coating liquid, and after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition. Moreover, among these resins, those which do not soften or melt before the resin is thermally decomposed are preferable. in particular,
Examples include phenol resin, epoxy resin, urea resin, melamine resin, and alkyd resin.

Examples of electron beam irradiation-curable resins include unsaturated prepolymers,
Examples include maleic anhydride type, urethane acrylic type, and polyester acrylic type.

A carbon blank may be further added to the magnetic layer.

This carbon blank is preferably electrically conductive, but a light-shielding material may also be added. As such a conductive carbon blank, for example, Conductex 97 manufactured by Columbia Carbon Co., Ltd.
5 (specific surface area 250 m/g, particle size 24 mμ), Conductex 900 (specific surface area 125 n?/g, particle size 2
7 mμ), Cabot Vu
lcan) As the light-shielding carbon black, for example, Raven 2000 manufactured by Columbia Carbon Co., Ltd.
(specific surface area 190 mf/g, particle size 18 m, u), 210
0.1170.1000, #100 manufactured by Mitsubishi Chemical Corporation,
#75, #40, #35, #30, etc. can be used.

Carbon black has an oil absorption of 90mj! (D
BP) /100g or more is desirable because it facilitates forming a struttle structure (and exhibits higher conductivity).

In the present invention, the magnetic recording medium has magnetic layers 20 on both sides of a support 1, as shown in FIG. 10, for example.

The magnetic powder, particularly the ferromagnetic powder, used in the magnetic layer 20 is γ-Fe 203,C.

Contains r-Fe 203, Fe3O4, co-contains Fe3O
Iron oxide magnetic powder such as No. 4; F e , N i % Co,
Fe-Ni-Co alloy, Fe-Mn-Zn alloy, Fe-
Ni-Zn alloy, Fe-Co-Ni-Cr alloy, Fe-
Co-N1-P alloy, (:, o-Ni alloy etc. Fe, Ni
Various ferromagnetic powders such as metal magnetic powders containing , Co, etc. as main components can be mentioned. Among these, Co-containing iron oxide and metal magnetic powder are preferable.

Further, the BET value of the magnetic powder is preferably 25 ryf/g or more, more preferably 30 d/g or more, the magnetic powder exhibits an acicular shape, and the viscosity of the magnetic paint is usually 1000 to 5000 CPS. The magnetic layer 20 also contains a lubricant (for example, silicone oil, graphite, molybdenum disulfide, tungsten disulfide,
A fatty acid ester consisting of a monobasic fatty acid having 12 to 20 carbon atoms (e.g. stearic acid) and a monohydric alcohol having 13 to 26 carbon atoms, etc.), abrasives (e.g. fused alumina), antistatic agents (e.g. Graphite) etc. may be added.

Note that in the magnetic recording medium of FIG. 10, it is not necessarily necessary to provide an undercoat layer (not shown) between the magnetic layer 20 and the support 1.

In addition, when coating and forming the above-mentioned magnetic layer, etc., it is desirable to add a predetermined amount of polyfunctional isocyanate as a crosslinking agent to the coating material. Examples of such crosslinking agents include, in addition to the polyfunctional polyisocyanates mentioned above, triphenylmethane triisocyanate, tris-(P-isocyanate phenyl) thiophosphite, polymethylene polyphenylisocyanate, methylene diisocyanate, tolylene diisocyanate, etc. Isocyanate type is better.

The materials for the support 1 mentioned above include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, plastics such as polycarbonate, and Aβ. , metals such as Zn, etc. are used. The thickness of these supports is approximately 3 to 100 μm, preferably 20 to 75 μm in the case of a film or sheet, 30 to 10 μm in the case of a disk or card, and cylindrical in the case of a drum. The type is determined depending on the recorder used.

Coating methods for coating the magnetic paint onto the support to form a magnetic layer include air knife coating, blade coating, doctor blade coating, air knife coating,
squeeze coat, impregnation coat, reverse roll coat,
Transfer roll coat, gravure coat, kiss coat, cast coat, spray coat, etc. are available.
Other methods are also possible.

In FIG. 1, a support 1 is conveyed to a magnetic paint coating means 3 to form a coating film containing magnetic particles, and while passing through a first orienting magnetic field 4, the magnetic particles in the coating film are transferred in the conveying direction. 8
oriented in a direction that intersects with In this way, the orientation of the magnetic particles mechanically oriented in the direction parallel to the transport direction 8 in the coating means 3 is canceled out.

Next, while the support 1 passes through the second orientation magnetic field 5, the magnetic particles in the coating film move in the coating film in an attempt to be oriented in the transport direction 8 and/or the opposite direction. Before the support 1 is completely oriented in this direction, the coating film is dried by entering the drying means 6 and the movement of the magnetic particles is stopped, so that the orientation of the magnetic particles becomes random and becomes non-oriented. In order to increase the degree of non-orientation, a part of the downstream side of the second orientation magnetic field 5 is configured to protrude into the drying means 6, and the magnetic particles are moved in the second orientation magnetic field 5. It is desirable to allow drying to begin during this time.

The magnetic particles become non-oriented and the coating dries to form the magnetic layer 20 (
10) is formed with a calendar part 7.
The film is then wound onto a winding roll 22.

To form the magnetic layer 20 on both sides of the support 1 as shown in FIG. 10, the above steps are repeated twice, for example.

Next, 40 examples of the first orientation magnetic field will be explained.

FIG. 2 is a partial plan view of the first orienting magnetic field 4, in which the bar magnets 4a are arranged at an angle θ with respect to the transport direction of the support 1 (indicated by arrow 8).

FIG. 3 is an enlarged cross-sectional view taken along the line m-m in FIG. 4b are arranged to face each other, and the lines of magnetic force 9 are oriented in a direction inclined by θl with respect to the transport direction 8 of the support 1.

Magnetic particles (not shown) in the coating film, which are mechanically oriented in the transport direction 8 by the opposing roll 3a (see FIG. 1) in the coating means 3, are oriented in the direction of the magnetic lines of force 9. This is the first step for non-orientation.

The angle θ in Figure 2 is -80° to -10° or 10° to 8
It is preferable to set the angle within the range of 0''.The angle θ is indicated by a plus sign on the right side and a minus sign on the left side in the figure with respect to the conveyance direction 8 of the support body 1.

The smaller the absolute value of the angle θ, the more pronounced the conveying force will be in the direction of the portion of the magnetic lines of force (9 in FIG. 3) that is close to the support 1.
If this is made too small, an extremely long magnet will have to be used to cover the width of the support 1.
It's inconvenient. From this point of view, the absolute value of the angle θ is preferably 10° or more.

On the other hand, in a range where the absolute value of the angle θ exceeds 80°, the direction of the portion of the magnetic force lines close to the support 1 approaches parallel to the conveyance direction 8, making it insufficient as the first step for non-orientation.

As described above, the absolute value of the angle θ includes a contradictory element: from the viewpoint of effectiveness, the smaller the value, the better, and from the viewpoint of device design, the larger the value, the more convenient. In order to make the movement of the magnetic particles sufficiently active and not make the length of the magnet 4a too long, the absolute value of the angle θ should be set to 45°.
It is preferable to set it in the range of ~75°.

As shown in Fig. 3, the bar magnets 4a and 4b may be one set with the same polarity facing each other, or if one set is insufficient, two or more sets may be used. and the opposite side (either one of 4a and 4b), or one piece may be placed on one side and a plurality of pieces may be placed on the other side.

It is particularly desirable that the strength of the orienting magnetic field be equal to or less than the coercive force of the magnetic particles, particularly 10 to 50% of this coercive force. Also, when using multiple magnets, it is desirable that the magnetic field strength be the same, and This is advantageous from the viewpoint of making the operation easier.

Note that a solenoid coil can be used instead of the bar magnet.

Furthermore, in the above example, bar magnets are used to form lines of magnetic force in opposite directions to orient the magnetic particles, but as shown in FIG. 4, an electromagnet 4c is used to form lines of magnetic force 10 in only one direction. However, the magnetic particles may be oriented. In this case, the power supplied to the electromagnet is alternating current or direct current with a sufficiently low frequency.

In the above example, the support is passed through the first orienting magnetic field following the application of the magnetic paint, but both steps are performed simultaneously, i.e., the magnetic paint is applied in the first orienting magnetic field. It is also possible to do so.

By doing so, it is possible to downsize the device.

Next, an example of the second orientation magnetic field will be described.

In the second alignment magnetic field 5, n bar magnets 5a-1, 5a are arranged such that the same poles face each other with the support 1 in between and adjacent poles are alternated in the transport direction 8. -2,・
......, 5a-n and 5b-1, 5b-2,
......, 5b-n are arranged. These bar magnets are all arranged in a direction perpendicular to the transport direction 8. The bar magnets downstream of the bar magnets 5a-3 and 5b-3 are in the drying means 6, and the bar magnets 5a-3 and 5b-3 are in the drying means 6.
, 5b-3, the hot air 6b is blown from the nozzle 6a and the magnetic particles of the coating enter the second orientation magnetic field 5, and the bar magnets 5a-1, 5a-2, . . .・・・・・・、5
a-n and 5b-1, 5b-2, ......
5b-n receives an action of being oriented in the conveying direction 8 from the magnetic force lines 11 (parallel to the III conveying direction 8). However, before the magnetic particles are completely oriented in the transport direction 8, the drying of the coating film is started by the hot air 6b, and the movement of the magnetic particles is blocked by the drying of the coating film while the magnetic particles are being oriented in the transport direction 8. , the direction will be random. As a result, the magnetic particles become non-oriented.

In the example shown in Fig. 5, the lines of magnetic force of each magnet are independent, but the lines of magnetic force of each magnet are independent.
As shown in the figure, lines of magnetic force may be formed across adjacent poles.

Further, as shown in FIG. 7, the coating film side with respect to the support 1,
The magnets may be placed on either side of the coating film (on the coating film side in FIG. 7), or the magnets may be placed so that adjacent poles are the same.

Also, as in the first orienting magnetic field, a DC solenoid coil can be used instead of the bar magnet, and
As shown in FIG. 8, it is also possible to form magnetic lines of force 12 by the electromagnet 5C, thereby making the magnetic particles non-oriented. In this case, the electric power supplied to the electromagnet is an alternating current or direct current with a sufficiently low frequency, as in the case of the electromagnet 4c shown in FIG.

The magnetic field strength should be smaller than the coercive force of the magnetic particles, and should be 10 to 50% of the coercive force of the magnetic particles, as in the first orientation magnetic field.
It is preferable to set it as approximately.

The direction of the magnetic field lines at the entrance end of the second orientation magnetic field is opposite to the direction of the magnetic field lines at the exit end of the first orientation magnetic field to more completely eliminate the non-orientation of the magnetic particles. desirable for.

The number of magnets in the second orientation magnetic field (n above) is preferably 3 or more, more preferably 10 or more.

Further, it is preferable that the magnetic field strengths of these magnets be the same from the viewpoint of operability of the device.

The second orientation magnetic field and drying start time will be described as follows.

Preferably, the support is passed through the magnetic field of at least one or one set of magnets, preferably two or more or more sets, after substantially drying has begun. Since drying is not completed immediately after the actual drying starts, if the movement of the magnetic particles continues during the drying process,
The movement of magnetic particles becomes slower as drying progresses,
Eventually, the magnetic particles become fixed. As described above, when a portion of the second orientation magnetic field on the latter side overlaps with the drying means, the orientation of the magnetic particles becomes partially random, and the magnetic particles 21 ( (see FIG. 10) becomes highly non-oriented. In particular, when manufacturing magnetic disks that require a high degree of non-orientation, it is preferable to do as described above.

Drying can be done by forced drying with wind as in the above example, natural drying (in this case, use a quick-drying binder resin), drying with a halogen heater lamp or infrared lamp, or any other appropriate method. It can be done by

In the above example, the orientation magnetic field in the first stage is an orientation magnetic field with a magnetic field tilted at the angle θ as described above with respect to the support transport direction, and the orientation magnetic field in the second stage is an orientation magnetic field with a magnetic field in the support transport direction. There is. By doing so, it becomes easy to increase the non-orientation of the magnetic particles, but the orienting magnetic fields do not necessarily have to be arranged in this order. That is, it is also possible to use an orientation magnetic field in the first stage as an orientation magnetic field with a magnetic field in the support transport direction, and a second stage as an orientation magnetic field with a magnetic field in a direction tilted at an angle θ with respect to the support transport direction. be.

Next, the present invention will be explained by giving specific examples.

On one side of a support made of polyethylene terephthalate with a thickness of 75 μm, a magnetic paint having the composition shown in Table 1 below was applied using a doctor blade method at a conveying speed of 29 m/+win so that the thickness after drying was 2.2 μm. The magnetic recording medium manufactured under these conditions was subjected to non-orientation treatment under the conditions shown in Table 2 below.
The squareness ratio II in the conveyance direction and the squareness ratio in the direction perpendicular to the conveyance direction are respectively measured, and these ratios, that is, the orientation degree ratio (/I
/Top) 0. was calculated. Here, the squareness ratio refers to (residual magnetic flux density/maximum magnetic flux density). In addition, in order to confirm the influence of the first orientation magnetic field, the squareness ratio in the direction of 45° with respect to the conveyance direction was set as //, -, and the squareness ratio in the direction of -45° with respect to the conveyance direction was determined as follows.
/-45' was measured, and considering 114S° to be soil-41, the ratio (/I/work)-49.

The results are shown in Table 3 below.

Comparative Example 2 in Table 3 shows the value of mechanical orientation in the coating process without providing an orientation magnetic field. Moreover, Comparative Example 1 showed an example in which non-orientation was achieved by using only the second orientation magnetic field as the orientation magnetic field. Generally, the orientation ratio of magnetic recording media is approximately 1.0 in either direction.
0.05 or less, but in Comparative Examples 1 and 2, (H/engine)-45・shows a value close to 1.00, but (///engine)0・ is 1.05. This requirement is not met. This is also considered to be a major hindrance to the recent trend of increasing the coercive force of magnetic particles and decreasing the thickness of the magnetic layer, as well as efforts to increase coating speeds in order to achieve high productivity. .

In contrast, all of the examples show satisfactory orientation ratios, fully satisfying the upper limit of orientation ratio of 1.05 required for magnetic disks, and completely free of orientation. There is.

As described in detail, the first aspect of the present invention is to form a layer containing magnetic particles on a support, and to orient the magnetic particles in a direction crossing the moving direction of the support. Since the support is passed through a plurality of orienting fields including a magnetic field and an orienting field that orients the magnetic particles in the direction of movement of the support and/or in the opposite direction, the magnetic particles are subjected to multiple orientations in which the directions are not significantly different. Orientation treatment is performed. Therefore, the movement of the magnetic particles is easy, and as a result, the resulting magnetic recording medium is highly non-oriented.

In addition, the second aspect of the present invention is configured such that a portion of the latter of the plurality of alignment magnetic fields is located in the drying means, so that in addition to the above-mentioned effects, The following effects can be achieved.

That is, drying begins during the subsequent orientation process, and the magnetic particles are fixed during the subsequent orientation process, resulting in a highly non-oriented magnetic recording medium.

[Brief explanation of the drawing]

The drawings all show embodiments of the present invention; FIG. 1 is a schematic diagram showing an overview of the manufacturing process of a magnetic recording medium, FIG. 2 is a schematic plan view of the first alignment magnetic field, and FIG. is an enlarged sectional view taken along the line m-m in FIG. 2, FIG. 4 is a schematic internal front view of another first orientation magnetic field, and FIG. 5 is a schematic internal front view of the second orientation magnetic field and drying means. Figures 6, 7, and 8 are schematic internal front views of other second orientation magnetic fields, Figure 9 is a plan view showing the direction of squareness ratio measurement, and Figure 10 is an enlarged cross-sectional view of the magnetic recording medium. It is. In addition, in the reference numerals shown in the drawings, 1......Support 3...Magnetic paint coating means 3c...
...Magnetic paint 4...First orientation magnetic field 5...Second orientation magnetic field 4a, 4b, 5a-1, 5a-2, 5a- 3,5a-n
, 5b-1, 5b-2, 5b-3, 5b-n...
...Bar magnet 4c, 5cm 1.5cm 2.5cm 3.6...
... Drying means 6a ... Nozzle 6b ... Warm air 8 ... Support conveyance direction 9.10.11.12.・・・・・・Magnetic field lines 20・
...... Magnetic layer 21 ...... Magnetic particles.

Claims (1)

[Scope of Claims] 1. A layer containing magnetic particles is formed on a support, the support is sequentially passed through a plurality of alignment magnetic fields, and one of the alignment magnetic fields is applied to the support. an orientation magnetic field in a direction intersecting the moving direction of the support, and the other orientation magnetic field is an orientation magnetic field in the moving direction of the support and/or the opposite direction. 2. means for forming a layer containing magnetic particles on a support; an orienting magnetic field in a direction intersecting the moving direction of the support;
a plurality of orienting magnetic fields consisting of an orienting magnetic field in the moving direction of the support and/or an orienting magnetic field in the opposite direction thereof; and a drying means for drying the layer, wherein a part of the latter side of the plurality of orienting magnetic fields is An apparatus for manufacturing a magnetic recording medium, located in a drying means. 3. Claim No. 3, wherein the first-stage orienting magnetic field is an orienting magnetic field in a direction that intersects the moving direction of the support, and the second-stage orienting magnetic field is an orienting magnetic field in the moving direction of the support and/or the opposite direction. 2. The magnetic recording medium manufacturing apparatus according to item 2.