JPS6032889B2 - Manufacturing method for magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording body, and particularly to a novel method for manufacturing a magnetic recording body having a plurality of magnetic layers with different orientation directions.

That is, the present invention provides a magnetic recording medium having one or more magnetic recording layers in which ferromagnetic particles are dispersed in a binder.
In particular, the present invention relates to a method for efficiently manufacturing a device having a plurality of magnetic recording layers having different magnetic properties. recent years,
As magnetic recording methods become more dense and diversified, it has become necessary for magnetic recording layers to have a so-called multilayer structure consisting of a plurality of layers. For example, as the recording density of broadcast video tapes increases, the magnetic recording layer has a so-called multilayer structure consisting of two layers: (1) a surface layer (upper layer) mainly responsible for recording short wavelengths such as video signals (b) The inner layer (lower layer), which is mainly responsible for recording relatively long wavelengths such as audio signals and control signals, has magnetic particles oriented in the tape's center direction or in a direction perpendicular to the tape surface. A need has arisen for something that can be used in the longitudinal direction of the tape.

That is, such tapes are particularly useful for video recording.
It exhibits high sensitivity to video, audio, and control signals, making high-density recording possible. In addition, the upper layer has magnetic particles oriented perpendicular to the tape surface, and the lower layer has magnetic particles oriented in the longitudinal direction of the tape, which has the characteristic of high audio output, and is suitable for audio tapes and video tapes. It is particularly suitable for both tapes.

With the diversification of magnetic recording, the use of cards having a magnetic recording layer, so-called magnetic cards, has recently become popular.

With the multiplexing of magnetic recording (for example, recording that is rewritable and recording that is difficult to rewrite using normal means), magnetic cards having stacked magnetic recording layers are becoming necessary. A magnetic recording body having a plurality of stacked magnetic layers in which the orientation directions of the magnetic layers are different has already been proposed.

German Patent Publication No. 1190985, US Patent No. 37751
The specification of No. 78 discloses a magnetic recording medium having a structure as shown in FIG.

That is, a lower layer 22 and an upper layer 23 are provided on the support 21, and the lower layer 22 is oriented in the longitudinal direction (also called the tape running direction or the audio direction), and the upper layer 23 is oriented as shown by the mark 24 in the figure. As shown by mark 25 in the figure,
The magnetic recording body is shown oriented in the tape's mid-direction (video direction) nearly perpendicular to the underlying layer. Such magnetic recording bodies are particularly suitable for use in four-head broadcast video tape recorders. U.S. Patent No. 3185775, U.S. Patent No. 3052567 (same content as Tokukokoku No. 5351/1973), Specification
The device disclosed in Japanese Patent No. 88911 has a configuration as shown in FIG.

That is, a lower layer 22 and an upper layer 31 are provided on the support 21. The lower layer 22 is oriented in the longitudinal direction as shown by the mark 24 in the figure, and the upper layer 31 is oriented in the longitudinal direction as shown by the mark 32 in the figure. The magnetic recording bodies are shown oriented in the thickness direction of the tape. Such magnetic recording bodies are particularly suitable for use in four-head broadcast and small video tape recorders, and have excellent frequency characteristics when used for audio recording. Also special public service 1977-1520
Publication No. 3 discloses a configuration that is almost similar to these.

That is, in order to reduce head wear, a magnetic recording body is shown in which the magnetic material in the upper layer is inclined with respect to the surface of the magnetic coating film. FIG. 3 shows an example of a magnetic card with stacked magnetic layers.

That is, a lower layer 42 having a high coercive force and an upper layer 43 having a relatively low coercive force are provided on a base 41, and the orientation direction of the lower layer 42 (indicated by mark 45 in the figure) and the orientation of the upper layer 43 are determined. The directions (indicated by marks 46 in the figure) are substantially perpendicular to each other. In such a magnetic card, normal recording and output is performed in the long side direction of the card by the upper layer 43, and records that are difficult to erase in the short side direction of the card are made in the lower layer 42. It is something that In addition, as shown in Figure 4, sheets suitable for rotational use are cut out from stacked magnetic recording webs in a circular shape, and in a recording method that magnetizes all layers (for example, digital), a uniform high output is produced over the entire circumference. can be obtained.

If the magnetic layers are stacked, a non-magnetic intermediate layer may be present between the magnetic layers. Such a magnetic layer is
No. 18135 and Japanese Unexamined Patent Publication No. 111605/1983. FIG. 5 shows its structure, in which a lower layer 22 is provided on a support 21, and an intermediate layer 51 (non-magnetic) is provided between the upper layer 61 and the lower layer 22. In this example, the orientation of the lower layer 22 (indicated by mark 24 in the figure) and the orientation of the layer 61 (indicated by mark 62 in the figure) are almost at right angles, and the intermediate layer is attached to the magnetic recording body shown in FIG. It corresponds to the addition of Such an intermediate layer is said to have the effect of reducing demagnetization caused by pressurization of the magnetic layer and preventing noise at the boundary between the magnetic layers. Although there is no difference in the orientation direction of the upper and lower layers, examples of magnetic recording bodies having multiple layers include U.S. Pat. No. 2,691,072, U.S. Pat.
No. 9996, No. 3416949, No. 3676217, No. 3761311, Japanese Patent Publication No. 37-2218, No. 39-8106, No. 39-23678, No. 43
-185, No. 48-28681, Tokukan Sho 47-183, No. 47-31602, No. 48-8109
No. 3, No. 49-55304, No. 49-111605, No. 50-31804, etc.

When manufacturing a magnetic layer having multiple layers, the sublayer first coats the lower layer on the support, aligns it, dries it, smoothes the surface, and then coats the upper layer on the lower layer on the support. Conventionally, it has been common practice to reorient the material, dry it, smooth the surface, and then perform pongee cutting.

In this case, in order to prevent the already provided lower layer from being destroyed by the coating liquid for the upper layer, a thermosetting binder is usually used for the lower layer. Thermosetting binders are generally more expensive than thermoplastic binders. A magnetic layer formed using a thermosetting binder is strong against friction with the head, and is characterized by high durability as a tape. However, when a thermosetting binder is used as the lower layer in order to obtain a multilayer recording medium by repeating coating as described above, the advantage of improved durability is not utilized at all. Furthermore, in such conventional methods, the flatness of the lower layer is extremely important in order to form a smooth upper layer, and therefore it is important to smooth the surface of the lower layer before applying the upper layer. For this reason, it was necessary to apply a supercalender treatment after forming the lower layer. In addition, in such conventional methods, when the orientation direction of the magnetic material in the upper layer and the orientation direction of the magnetic material in the lower layer are made to be different, the direction of the orientation treatment performed when coating the lower layer,
This was achieved by manufacturing the film in a direction different from the direction of the orientation treatment performed when coating the upper layer.

The conventional method of manufacturing a multilayered magnetic recording medium as described above is very time-consuming, and it is difficult to avoid losses during manufacturing and high costs.

A simultaneous multilayer coating method has been proposed as a method to solve the drawback of repeating the coating process for each layer.

(For example, Tsubaki Publication No. 48-198803) However, in the case of this simultaneous multilayer coating method, it was difficult to make the orientation directions of the magnetic materials in the upper layer and the lower layer different. This is because when an orientation magnetic field is applied, both the upper layer and the lower layer are oriented in the same direction. The present invention was developed as a result of repeated research to improve the drawbacks of the conventional manufacturing method for multilayered magnetic recording bodies as described above.
The present invention was achieved by discovering that the above object can be achieved by a method of transferring and adhering a magnetic layer (upper layer) provided on a temporary support onto a magnetic layer (lower layer) provided on a non-magnetic support. The method of the present invention will now be explained in more detail with reference to FIGS. 6 to 8.

FIG. 6 is an example of a vertical sectional view showing an overview of the present invention.

That is, a magnetic layer 22 is provided on a support 21 made of a nonmagnetic material. The support on which the web is prepared has a thickness of, for example, 5
It is a polymer film of Buddha skin to 1005 Buddha. The magnetic layer 22 includes at least ferromagnetic powder and a binder.
The thickness is, for example, 0.5 Am to 25 ridges. In this example, it is desirable that the magnetic layer 22 contains a thermoplastic resin. The surface of the magnetic layer 22 is heated by an infrared lamp 69 having a reflecting mirror 68. This infrared lamp 69 is auxiliary to the heating by the pressure roller. The magnetic layer 22 on the support 21 is fed between a pair of post-pressing rollers 65 and 66. On the other hand, the magnetic layer 23 (thickness is the same as the range 22) on the temporary support 67 is also sent between pressure rollers 65 and 66. The magnetic layer 22 and the magnetic layer 23 are closely pressed between the rollers. Then, the magnetic layer 23 and the temporary support 67 are separated at the interface,
The temporary support body 67 is moved to the right in the figure. The temporary support 67 is preferably in the form of a web with a smooth surface. As the temporary support 67, various colored or colorless polymer films, metal bands, etc. are used. Also, a metal drum may be used. In the case of films, bands, etc., it is preferable that they have some degree of flexibility. At that time, the desired thickness is 5 mounds to 2 ribs, and particularly preferably 75 m to 0.8 m. The magnetic layer 22 on the support 21 and the magnetic layer 23 on the temporary support 67 are each formed by known methods. In this example, it is assumed that the magnetic layer 22 is subjected to a magnetic field orientation treatment in the running direction of the web, and the magnetic layer 23 is subjected to a magnetic field orientation treatment in the direction in the direction of the web. Either or at least one of the pressure rollers 65 and 66 has a diameter of 30qo to 1300°, preferably 40° to 1
It is desirable that the temperature be heated to 05q0.

Heating generally makes the magnetic layer easier to adhere. Before forming the magnetic layer 23 on the surface of the temporary support 67, it is also possible to treat the surface of the temporary support 67 with a material that improves mold release properties (for example, silicone oil, Huqin oil, etc.).
This is effective in facilitating transfer adhesion of the magnetic layer 22 to the magnetic layer 22. Thus, as shown on the left side of FIG. 6, a magnetic layer 22 (the magnetic material is oriented in the web running direction) and a magnetic layer 23 (the magnetic material is oriented in the web direction) are formed on the flexible support 21. ) are provided in an overlapping manner. (Similar to Figure 1). It can be seen that so-called surface treatment (supercalender, surface polishing, etc.) is not particularly necessary in obtaining a magnetic medium having a so-called multilayer magnetic layer according to the present invention. That is, surface smoothing, which is one of the effects of a calendar, is achieved by smoothing the surface of the temporary support 67. That is, by controlling the surface properties of the temporary support 67, the surface properties of the obtained magnetic recording body can be adjusted. In the present invention, the effect of increasing the density (higher filling) of the magnetic layer, which is another effect of the calendar, can be obtained by applying pressure between press rolls during transfer bonding. Of course, each of the magnetic layers 22 and 23 may be calendered in advance. Furthermore, calendering after transfer adhesion has the effect of further increasing surface properties and filling degree. If a magnetic layer oriented perpendicular to the web surface is used instead of the magnetic layer 23 in this example (which is oriented in the direction of the web), a magnetic recording body such as that illustrated in FIG. It is easily understood that a magnetic card as shown in the figure can be obtained. In this example, the magnetic layer 22 (lower layer)
In the above example, a thermoplastic binder was used, but of course, either or both of the magnetic layer 22 and the magnetic layer 23 may contain a thermoplastic binder.

FIG. 7 is another example of a vertical sectional view showing a certain situation in which the present invention is implemented.

A magnetic layer 22 is provided on a support 21 made of a non-magnetic material.

The magnetic layer 22 on the support 21 is fed between a pair of pressure rollers 65 and 66. On the other hand, the magnetic layer 61 is placed on the temporary support 67.
Furthermore, the thermoplastic material 51 stacked on the outside thereof is also sent between pressure rollers 65 and 66 in the same way. magnetic layer 2
2 and the thermoplastic layer 51, the thermoplastic layer 51 may be heated by, for example, an infrared lamp 11 (70 is a reflecting mirror), if necessary. Child fever can also be generated by blowing hot air or the like. The magnetic layer 22 and the thermoplastic layer 51 are closely pressed between the loafs 65 and 66. Preferably, each roller is heated as previously discussed. The thermoplastic layer is a layered layer of a conventionally known thermoplastic polymer material. The thickness is preferably in the range of 0.05 mm to 3 mm, preferably 0.08 mm to 1 mm. It has been found that if it is too thin, the adhesive effect is low, and if it is too thick, the frequency characteristics during magnetic recording deteriorate. After pressure acid between the rollers, the magnetic layer 61
The temporary support 67 is separated at the interface between them, and the temporary support 67 is moved to the right in the figure. It is easy to understand that by such a process, a magnetic recording medium having a structure as shown in FIG. 5, for example, can be obtained. In the case of having a thermoplastic intermediate layer as in this example, both the magnetic layer 22 and the magnetic layer 61 may use only a thermosetting binder. Next, FIG. 8 shows another example of the present invention in which a magnetic layer is further stacked on a magnetic layer provided on a relatively rigid support.

A magnetic recording body consisting of a magnetic layer 42 provided on a relatively rigid non-magnetic support 41 is placed on a rigid stand 76. The magnetic layer side of the web carrying the magnetic layer 43 on the temporary support 75 is placed opposite to the magnetic layer 42 . The magnetic layers 43 and 42 are closely bonded using a pressure roller 77 from above the web (back side of the temporary support). The pressure roller 77 rotates and is moved to the left as indicated by the arrow in the figure. The magnetic layer 43 is pressed together with the magnetic layer 42 and peeled off from the temporary support 75 . Also in this example, it is desirable that at least one of the magnetic layers 42 and 43 contains a thermoplastic binder. When using a manufactured fake magnetic material, it is normal to touch the head for recording and playback, or to use it very close to the head, so the upper layer (outermost layer) must be durable. It is desirable that there be. For this purpose, it is desirable that the upper layer binder contains a thermosetting binder. Therefore, it is desirable that the upper magnetic layer be made of a thermosetting binder alone or a mixture of a thermosetting and thermoplastic binder. Further, when the upper layer is made of a thermosetting binder alone, the lower magnetic layer is desirably made of a thermoplastic binder alone or a mixture of thermoplastic and thermosetting binders. Magnetic coating liquids made using a thermosetting binder tend to have a shorter pot life than those made using a thermoplastic binder. Further, since thermosetting binders are more expensive than thermoplastic binders, it is desirable that the amount of thermosetting binder contained in the magnetic tape is small. Therefore, as a binder when carrying out the present invention, it is desirable that the upper layer (outermost layer) uses a thermosetting binder or a binder that is a mixture of thermosetting and thermoplastic, and the lower layer uses a thermoplastic binder.
The following resins are used as binders. As a thermosetting resin or a reactive resin, it has a molecular weight of 200,000 or less in the state of a coating solution, and is suitable for coating,
By adding it after drying, the molecular weight becomes infinite due to reactions such as condensation and addition.

Also, among these resins, those that do not soften or melt before the resin is thermally decomposed are preferred. Specifically, examples include phenol resin, eboxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, syringo resin, acrylic reaction resin, mixture of high molecular weight polyester resin and isocyanate prepolymer, and methacrylate copolymer. mixtures of polymers and diisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanates, polyamine resins and mixtures thereof, etc. . Examples of these resins are given in Japanese Patent Publication No. 39-8103.
No. 40-1977, No. 41-7192, No. 41
No. 18016, No. 41-14275, No. 42-181
No. 79, No. 43-12081, No. 44-28023, No. 45-14501, No. 45-24902, No. 4
No. 6-13103, No. 47-22065, No. 47-2
No. 2066, No. 47-22067, No. 47-2207
No. 2, No. 47-22073, No. 47-228045, No. 47-28048, No. 47-28922,
US Pat. No. 3,144,353; US Pat. No. 3,320,090: US Pat. No. 3
No. 43751: No. 3597273: No. 378121
No. 3781211.

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 20.
Those with a prevalence of 0 to 200, such as 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 combination, ester acrylate styrene copolymer, ester methacrylate acrylonitrile copolymer,
Methacrylic acid ester vinylidene chloride copolymer, methacrylic acid ester styrene copolymer, urethane elastomer, polyvinyl fluoride, pinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer, polyamide resin, polypynyl butylar cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene butadiene copolymer, polyester resin, chlorovinyl ether acrylate copolymer Polymers, amino resins, various synthetic rubber-based thermoplastic resins, and mixtures thereof are used. Examples of these resins are Samurai Ko No. 37-16877, Samurai Ko No. 39-12528, Samurai Ko No. 39-19282, Samurai Ko No. 40-
No. 5349, No. 40-20907, No. 41-9463
No. 41-1405, No. 41-16985, No. 42-6428, No. 42-11621, No. 43-4
No. 623, No. 43-15206, No. 44-2889, No. 44-17947, No. 44-18232, No. 4
No. 5-1402, No. 45-1450, No. 47-1
No. 8573, No. 47-2063, No. 47-22064
No. 47-22068, No. 47-22069, No. 47-22070, No. 48-27886, U.S. Patent No. 3i44352: No. 3419420: No. 149
No. 9789: Described in the specification of No. 3713887.

These binders may be used alone or in combination, and other additives may be added. The mixing ratio of the ferromagnetic powder and the binder is 10 parts by weight of the ferromagnetic powder to 1 part by weight of the binder.
It is used in a range of 0 to 400 parts by weight, preferably 30 to 20 parts by weight. Regarding the manufacturing method of the magnetic paint used in the present invention, Japanese Patent Publication No. 35-11 No. 39-26794, No. 43
No. 1186, No. 47-28043, No. 47-2804
No. 5, No. 47-28046, No. 47-28048,
No. 47-31445, No. 48-11162, No. 48
It is described in detail in No. 21331, No. 48-33683, Soviet Patent Specification No. 308033, etc.

The magnetic paints described in these documents contain ferromagnetic powder, binder, and coating solvent as main components, and may also contain additives such as dispersants, lubricants, abrasives, and antistatic agents.
The ferromagnetic fine powder used in the present invention includes y-Fe2Q
, Co-containing y-Fe203, Fe304, Co-containing Fe804, bertolide compound of y-Fe208 and Fe304 (Feo 戊, 1.33 < x 1.50), Co
Bertolide compound of y-Fe208 and Fe304 containing (Fe0x, 1.33<x<1.50), C2, C
o-Ni-P alloy, Co-Ni-Fe alloy, Co-Ni
-Fe-B alloy, Fe-Ni-Zn alloy, Fe-Mn-
Known ferromagnetic fine powders such as Zn alloy, Fe-Co-Ni-P alloy, Ni-Co alloy, etc. can be used.
No. 22062, No. 47-22513, No. 46-284
No. 66, No. 46-38755, No. 47-4286,
No. 47-12422, No. 47-17284, No. 47
-1850 number, 47-18573, 39-10
No. 307, Publication No. 48-3963, U.S. Patent No. 302
No. 6215: No. 3031341: No. 3100194: No. 3242005: No. 3389014, British Patent No. 75265: No. 782762: No. 1007323
No.: French Patent No. 1107654: West German Published Patent No. OLS 1281334, etc.

The particle size of these ferromagnetic fine powders is about 0.2 to 1 micron in length, and the length/medium ratio is about 1/1 to 20/1. Various conductive powders or conductive agents are added to the magnetic layer for the purpose of preventing the magnetic layer from being charged.

In carrying out the present invention, these conductive additives may be contained only in the outermost layer. It has been found that by doing this, there is no need to include non-magnetic powder in layers other than the outermost layer, and the output is improved. Antistatic agents include conductive powders such as graphite, carbon black, and carbon black graft polymers; natural surfactants such as saponin; and ionic surfactants such as alkylene oxides, glycerin, and glycidol; higher alkylamines; Cationic surfactants such as quaternary ammonium salts, pyridine and other enomoto rings, phosphonium or sulfoniums: carboxylic acids, sulfonic acids, phosphoric acids,
Anionic surfactants containing acidic groups such as sulfate ester groups and phosphate ester groups; amphoteric surfactants such as amino acids, humic/sulfonic acids, sulfuric acid or phosphoric esters of amino alcohols, etc. are used.

Some examples of surfactant compounds that can be used as antistatic agents are disclosed in U.S. Pat.
No. 2288226, No. 2676122, No. 26
No. 76924, No. 2676975, No. 2691566
No. 2727860, No. 2730498, No. 27
No. 42379, No. 2739891, No. 3068101
No. 3158484, No. 3201253, No. 32
No. 10191, No. 3294540, No. 3415649
No. 3441413, No. 3442654, No. 34
No. 75174, No. 3545974, West German Patent Publication (OB) No. 1942665, British Patent No. 1077317, Specification No. 119845, etc., "Synthesis of Surfactants and Their Applications" by Ryohei Oda et al. (Yokoshoten 196 Sanno) Edition): AW. "Surf Act Agents" by IJ Bay (Interscience Publications Inc. 195 edition): T. P. "Encyclopedia of Surf Science Active Agents, Volume 2" (Chemical Publications Company 196, French edition) by John Sisley: Surfactant Handbook, 6th edition (Sangyo Tosho Co., Ltd., December 1968) It is written in books such as the 20th of May).

These surfactants may be added alone or in combination.

These are used as antistatic agents, but are sometimes used for other purposes, such as dispersion, improving magnetic properties,
It may also be used to improve lubricity and as a coating aid.
Various abrasive powders are added to the magnetic layer for the purpose of preventing foreign matter from adhering to the magnetic head and appropriately removing a fatigued layer that forms on the surface of the magnetic head.

In carrying out the present invention, these abrasives may be contained only in the outermost layer. It has been found that this eliminates the need to include nonmagnetic powder in layers other than the outermost layer, improving output. Commonly used abrasive materials include fused alumina, silicon carbide, and chromium oxide (Cr).
203), corundum, artificial corundum, diamond, artificial diamond, garnet, gemery (main components: corundum and magnetite), etc. are used.

These abrasives have an average particle size of 0.05 to 5 mm, particularly preferably 0.1 to 2 mm. These abrasives are used in an amount of 7 to 2 parts by weight per IO0 parts by weight of the binder.
It is added in an amount of 0 parts by weight. Regarding these, the specification of Japanese Patent Application No. 48-2674y, U.S. Pat.
No. 0910: No. 3687725: British Patent 11453
No. 49 West German Patent (DT-PS) No. 853211. Various lubricants are sometimes added to the magnetic layer for the purpose of reducing the friction that occurs between the magnetic layer surface and the magnetic head. In carrying out the present invention,
These powder lubricants may be added only to the upper layer (outermost layer). This eliminates the need to include nonmagnetic powder in layers other than the outermost layer, improving output. Also, lubricating wax, liquid, etc. should be added to one of the layers (preferably the upper layer).
It is only necessary to add it to It is believed that these additives that act in molecular form can move within the magnetic layer relatively easily. As a lubricant, silicone oil, carbon black, graphite, carbon black graft polymer,
:Molybdenum sulfide, tungsten disulfide, carbon number 12~
1 Fatty acid esters consisting of a hard monobasic fatty acid and a monohydric alcohol with 3 to 12 carbon atoms, a monobasic fatty acid with 17 or more carbon atoms, and a total of 21 carbon atoms in the fatty acid. Fatty acid esters made of monohydric alcohols having a hardness of ~23% can be used.

These lubricants are used in an amount of 0.2 to 10 parts by weight of the binder 10.
It is added in an amount of 2 parts by weight. Regarding these, the specifications of Japanese Patent Publication No. 43-23889, Chigan No. 42-28647, Chigan No. 43-181543, U.S. Patent No. 34
No. 70021: No. 3492235: No. 3497411
No. 3523086: No. 3625760: No. 36
No. 30772: No. 3634253: No. 364253: No. 3687725 Specification: "IBM Techn
ical Disclosme Bulletin”V
ol. 9” No. 7, Pa bag 779 (December 1966): “ELEKTRONIK” 1961,
No. 12, Page 380, etc. Dispersants include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid,
Fatty acids having 12 to 18 carbon atoms (R, COO, R
, is an alkyl group having 11 to 17 carbon atoms): a metal soap consisting of an alkali metal (Li, Na, K, etc.) or an alkali metal (Mg, Ca, parent) of the above-mentioned fatty acids: lecithin, etc. are used. .

In addition, higher alcohols having 1 or more carbon atoms and sulfuric acid esters can also be used. These dispersants are added in an amount of 1 to 2 parts by weight based on 10 parts by weight of the binder. For example, Tokuko Sho 39-2836y
No. 44-17945, No. 48-15001, and US Pat. No. 3,387,993: US Pat. No. 3,470,021.

To form the magnetic recording layer, the above-mentioned composition is dissolved in an organic solvent and applied as a coating solution onto a non-magnetic support.

This support is made of 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,
Non-magnetic metals such as Cu, AI, and Zn, and ceramics such as glass, porcelain, and earthenware are used.

The thickness of these non-magnetic supports is about 3 to 100 ridges in the case of a film or sheet, preferably 5 to 50 ridges, and about 0.5 to 1 ridge in the case of a disk or card. In the case of a cylindrical shape, the shape is determined depending on the recorder used.

As the temporary support used in the present invention, the same material as the above support is used, and the same can be said about the thickness etc. of the support.

The above support has a so-called back coat (back coat) on the side opposite to the side on which the magnetic layer is provided for the purpose of preventing static electricity, preventing transfer, etc.
coat).

Regarding the back coat, for example, US Patent No. 280,440
No. 1, No. 3293066, No. 3617378, No. 3
No. 062676, No. 3734772, No. 347659
No. 6, No. 2643048, No. 2803556, No. 2
No. 887462, No. 2923642, No. 299745
No. 1, No. 3007892, No. 3041196, No. 3
No. 11542, No. 3166688, etc.

The support may be in any form such as a tape, sheet, card, disk, or drum, and various materials may be selected as necessary depending on the form.

The magnetic powder and the above-mentioned binder, dispersant, lubricant, abrasive, antistatic agent, solvent, etc. are mixed into a slurry to form a magnetic paint.

When mixing the rice bran, the magnetic powder and each of the above-mentioned components are fed into a kneading machine either simultaneously or individually one after another.

For example, there is a method in which magnetic powder is first added to a solvent containing a dispersant and mixed for a predetermined period of time, and then the remaining components are added and the mixing is continued to produce a magnetic paint. Various types of crosstalk machines are used for trenching and dispersion.

For example, two roll mill, three roll mill, ball mill,
Vebble mill, Thoron mill, sand grinder, Sze
Biari attritor, high speed inveler dispersion machine, high speed stone mill, high speed impact mill, disper, kneader,
These include high-speed mixers, homogenizers, and ultrasonic dispersers. The technology regarding kneading and dispersion is described by T. C. “PaintFlowandPigmentDisp” by PATTON
version” (1964, John Wiley &amp;
(Published by Sons). It is also described in US Pat. No. 2,581,414 and US Pat. No. 2,855,156. Methods for coating the magnetic recording layer on the support include air doctor coating, plaid coating, air knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, kiss coating, cast coating, Spray coating etc. can be used, and other methods are also possible, and detailed explanations of these methods can be found in "Coating Engineering" 25 published by Asakura Shoten.
It is described in detail on pages 3 to 277 (Takayuki, Section 3, 2, 1977).

Organic solvents used during coating include ketoso-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol-based solvents such as methanol, alcohol, propanol, and butanol; methyl acetate, ethyl acetate, butyl acetate, Ester types such as ethyl lactate and acetate glycomonoethyl ether; Glycol ether types such as ether, glycol dimethyl ether, glycomonoethyl ether, and dioxane; Tar types such as benzene, toluene, and xylene; Aromatic hydrocarbons): Chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and dichlorobenzene can be used.

By such a method, the magnetic layer coated on the support is optionally treated to orient the magnetic powder in the layer, and then the formed magnetic layer is dried.

Further, the magnetic recording body of the present invention is manufactured by subjecting it to surface smoothing processing and cutting it into a desired shape, if necessary. In this case, the orientation magnetic field is about 50 to 2,000 Gauss in alternating current or direct current, and the drying temperature is about 50 to 100 gauss.
Drying time is about 3 to 10 minutes.

Methods for orienting magnetic powder are also described in the following patents: For example, US Patent No. 194984: 2796359
No.: 3001891: 3172776: 34
No. 16949: 347396 No. 3681138
No.: Special Publication No. 32-3427: No. 39-28368:
No. 40-23624: No. 40-23625: No. 41
-13181: No. 48-13043: No. 48-39
No. 722 specification, etc.

The orientation direction of the magnetic material is determined by its use.

That is, in the case of sound tapes, small video tapes, and memory tapes, it is parallel to the length and direction of the tape, and in the case of broadcast video tapes, it is oriented at an inclination of 300 to 900 with respect to the length direction. . The present invention will be explained in more detail below using examples.

It will be readily understood by those skilled in the art that the ingredients, proportions, order of operations, etc. shown in (a) above may be changed without departing from the spirit of the present invention. Therefore, the invention should not be limited to the examples below.

In addition, in the following examples, all parts indicate parts by weight.
Example a: Method for manufacturing web (1) serving as the upper magnetic layer.

(For the upper layer of a multilayer magnetic recording medium.) The following composition was kneaded.

Magnetic iron oxide (maghemite) '11 10 parts Polyester polyurethane '2) 8 parts vinyl chloride vinyl acetate copolymer '31 1 part oleic acid
1 part silicone oil (polydimethylsiloxane 0.6 part chromium sesquioxide (Cr2C8 average particle size 0.2)
1.2 parts butyl acetate
12$ Guo Methyl Isobutyl Ketone
6 Anchor part [11 y-Fe2 using iron sulfate as starting material
08, average major axis diameter 0.4 mm, needle ratio 8.5:1, A
PP value (Ave age PorePop mountain ation)
0. &Saturation magnetization 7$mu/evening thing.

'21 Polyester synthesized from adipic acid, terephthalic acid, etc. and ethylene glycol, diethylene glycol, butylene glycol, etc., is urethanized with 4,4'-diphenylmethane diisocyanate, etc.

Styrene equivalent weight average molecular weight approximately 130,000. A product of Nippon Reichhold, product name: Pandex T-52.
0 & glue Copolymerization ratio (mole): 83 cents: 17%, degree of polymerization approximately 500.

The above composition was placed in a ball mill and after being dispersed for 2 hours, polyisocyanate (an adduct of 3 mol of tolylene diisocyanate and 1 mol of trimethylolpropane) was added.

75% ethyl acetate solution, Nco content approximately 13.3% Bayer AG product, trade name, Desmodur L-75)
7 parts were added thereto, and the mixture was further subjected to high-speed sieving for 1 hour and filtered through a filter with an average pore diameter of 3 to obtain a coating solution.

Apply this coating liquid to a thickness of 1 mm so that the dry thickness of the skin is 3.1 mm.
2. The kite was placed on a polyethylene tereclate web as a temporary support having an extremely smooth surface (surface roughness of 0.08 mm or less, surface treated with a certain amount of silicone oil). Coated.

A DC magnetic field (strength: 1200 Oersted) was applied to the wet coating layer so that the magnetic material was oriented in the direction of the web.
The obtained magnetic layer has a coercive force of 325 Oersted and a saturation magnetization of 1
570 Gauss and a squareness ratio (in the middle direction of the web) of 0.82 ((all measured magnetic fields were 2000 Oe).

Since this magnetic layer becomes more easily peeled off than the temporary support as it hardens, it was stored in an atmosphere of 60 oo for one week. b
A method for manufacturing a web (0) with a flattened magnetic layer for the upper layer.

The following composition was kneaded. Chromium dioxide (C2) (4
} 10 Ikarikaku Polyester Polyurethane (
(same as ■) 8 parts pinyl chloride vinyl acetate copolymer (same as [3') 1 part soybean lecithin 1 part silicone oil (polydimethylsiloxane
0.7 parts Butyl acetate 1
2. Methyl isobutyl ketone 5. Modified with tellurium, average grain size of the most axis 0.5 μm, acicular ratio 9:1, APP value 0.0, saturation magnetization 7 steps μ
/Many things.

After putting the above composition in a ball mill and dispersing it for 2 feeding hours,
7 parts of polysocyanate (same as that used in coating liquid (1)) was added, and the mixture was further concentrated for 1 hour and filtered through a cylindrical filter having an average pore diameter of 3 mm to obtain a coating liquid.

Apply this coating solution to a dry thickness of 1.5 cm.
2. Coated on a web of polyethylene tereclate, which is a temporary support, which has an extremely smooth skin surface (surface roughness of 0.08 μm or less, surface treated with a certain amount of silicone oil). did. A DC magnetic field (strength 1500 Oersted) was applied to the wet coating layer so that the magnetic material was oriented in the direction of the web. The obtained magnetic layer has a coercive force of 52
5 Oersted, saturation magnetization 1640 Gauss, squareness ratio 0.8
7 was shown. This magnetic layer was stored at 60 qo for one week because it was easily peeled off from the temporary support as the hardening progressed. c. Manufacturing method of the web (m) that served as the lower magnetic layer.

(For lower layer of multilayer magnetic recording medium) The following composition was kneaded.

Magnetic iron oxide (maghemite) {51 10 parts Vinyl chloride pinyl acetate copolymer (same as {31) 25 parts Dioctyl phthalate 4 parts Oleic acid 1 part Methyl ethyl ketone 15 parts Tyl isobutyl ketone 15 parts Starting from sulfate Y-Fe208 used as raw material, average major axis diameter 0.57
Buddha's needle ratio 8:1, APP value 1. Fu saturation magnetization 7 clam mu
/ Evening thing.

After putting the upper layer composition into a pole mill and dispersing it for two hours,
The mixture was filtered through a cylindrical filter having an average pore diameter of 4 mm to obtain a coating solution.

Apply this coating solution to a polyethylene terephthalate film with a dry thickness of 6.4 mm (with a surface roughness of 0.4 mm).
2 or less).

The web surface has been previously subjected to corona discharge treatment to enhance adhesion of the magnetic layer. A DC magnetic field (strength 1
200 oersted) was applied. The obtained magnetic layer exhibited a coercive force of 305 Oersteds, a saturation magnetization of 1 and 0 Gauss, and a squareness ratio of 0.81. A multilayer magnetic material was created by combining the three types of magnetic layers described above.

Example 1 The magnetic surface of the web (1) and the magnetic surface of the web (m) are placed opposite each other and passed between a roll consisting of a metal roll and a cotton roll heated to 70 oo. The temporary support was peeled off.

The magnetic layer spread on the web (m) was further supercalendered at 50°C. The total magnetic layer of the wafer (m) was 8.0 mm. The web was then cut in the longitudinal direction to a 2-inch length to obtain a 2-inch video tape (for 4 heads). Let this be #1. Example 2 Web (D) and web (m) were stacked together under the same conditions as in Example 1, and the magnetic layer on the resulting web (m) had a total thickness of 7.9 degrees.

The resulting videotape is designated as #2. A thin broadcasting videotape (150% product, manufactured by Fuji Photo Film 706) was used as a standard, and a comparison was made with #1 and #2 using a broadcasting/e-band VTR (manufactured by Ambex).

gMHZ unbiased recording.

Let day 706 be M old. ** Day 706 is set as 100%. ***Measured at 400Hz. As is clear from this table, the videotape according to the present invention has an upper layer in the so-called video direction.
Since the lower layer is oriented in the audio direction and has excellent surface properties, it has excellent video sensitivity, audio sensitivity, and control track sensitivity.

#2 has high image sensitivity because it uses a high coercive force material (C2) for the upper layer.

[Brief explanation of the drawing]

1 to 5 show the structure of a magnetic recording medium obtained by the method of the present invention and to which the present invention is particularly effective, and FIGS. 6 to 8 are vertical sectional views showing an overview of the implementation of the method of the present invention. Spear 1 Picture Spear 2 Picture O 3 Picture Spear 5 Picture O 6 Picture Spear 7 Picture Spear 8 Picture

Claims (1)

[Claims] 1. Magnetic layer I, which is provided on a non-magnetic support and contains at least ferromagnetic powder and a binder, is provided on a temporary support and contains at least ferromagnetic powder and a binder. A method for manufacturing a magnetic recording medium having a plurality of magnetic layers with different orientation directions, characterized by bonding layer II by transfer.