JPS6032888B2 - magnetic sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic sheet, and particularly to a sheet whose output fluctuates little due to temperature changes.

The magnetic sheet is composed of a magnetic layer and a support substrate, and has a structure in which a protective layer is provided on the surface of the magnetic layer, and an antistatic layer or a running stabilizing layer is also provided on the support substrate, if necessary.

Conventionally, in order to equalize the contact force between the magnetic layer and the magnetic head,
1 Method of using magnetic sheets/heads in strong contact;
2) A method to reduce curling of the magnetic sheet, 3) A method to change the amount of head protrusion when the temperature rises, etc., but method 1 shortens the sheet life, and D.
0. The disadvantage of method 2 is that the curling of sheets at room temperature and high temperature is unstable, and the head touch is unstable, resulting in unstable output and envelope. The problem was that the curling was irregular.

Furthermore, the structure of the magnetic sheet device must be designed in accordance with the above method, which also causes the device to become complicated. Recently, magnetic sheets have been developed in the following ways: 1. Want to extend the life of the seat, 2
．． 3. The usable temperature range has been expanded. I want to reduce head wear. Improvements were made with the aim of
No contact between head and sheet (head/sheet gap is 0.
It is designed to be used in the 01-10A) state.
By this method, the above objects 1 to 3 were achieved at room temperature. However, the following problems still remain.

Namely 1. 2. At high temperatures (mainly above 40 pm), the reproduction output of the sheet suddenly decreases. Low temperature (mainly 5℃
(below), the seat life will suddenly shorten; 3. 4. Head wear is large at low temperatures. For example, dropout (D.0) occurs at high temperatures. From these facts, it can be seen that a sheet recorder using a mechanism with a non-touchable head sheet is an extremely excellent device at room temperature, but loses its characteristics at low and high temperatures.
The purpose of the present invention is to create a magnetic sheet for making an excellent recorder that is as good at low or high temperatures as it is at room temperature.

The inventors of the present invention investigated the causes of sheet property deterioration at high and low temperatures and discovered the following. In a non-contact coder where the head/sheet is non-contact, 1. The gap between the head and the seat changes depending on the temperature.

That is, at low temperatures, the gaps become small, and at high temperatures, the gaps become large. Therefore, at high temperatures, the output becomes small, and at low temperatures, the head/seat tends to come into contact, resulting in a shortened sheet life and increased head wear. When we investigated the cause of the change in flying height due to temperature, we found the following. [The Young's modulus of the magnetic sheet changes depending on the temperature, and the density and kinematic viscosity of air change depending on the temperature. However, curling tends to occur on the magnetic sheet. We examined and evaluated the magnitude of the impact on these items, and confirmed that the impact of these items is extremely large. Possible reasons for this are as follows. In a mechanism where the head and seat are non-contact, the aeroelastic behavior of the head/seat is as follows.

Since the sheet is slightly floating above the head, the sheet is under pressure from the fluid (air in this case) interposed between the head and the sheet. This pressure is necessary to create a small gap in the head sheet, and the magnitude of this pressure is sufficient to deform the sheet when applied to it. Therefore, the sheet is bent by the pressure, and the gap between the head and the sheet is maintained in the bent state. The bent state of this magnetic sheet changes depending on the temperature. The magnitude of deflection is expressed by the following formula according to the theory of elastic bodies. △1=Kichi K △1: Size of deformation = Deflection E = Young's modulus (of the sheet) 1: Section modulus of the sheet K: Constant depending on sheet shape and load type Size of this deflection (△1 ) corresponds to the floating height.

Since this Δ1 changes with temperature, it can be assumed that E or 1 shown in the above equation changes with temperature. Since it is clear that 1 does not change with temperature, it was found that E changes with temperature. Therefore, if E changes with temperature, for example, if the Young's modulus of the sheet at room temperature is E to C, and the Young's modulus of the sheet at t C is Et C, then the flying height of the sheet is E to C / E to C
It varies greatly depending on the ratio of Since the Young's modulus decreases with temperature, the E powder degree Celsius changes as shown below depending on the change in t degree Celsius.

{a} If too>20pmC, 0<EtqC/E2
o℃<1{bl If t℃=20:00, EtqC/E
2oqC=1[c' If t℃>20oo, EtqC
As a result of experiments, it has been found that the flying height of the sheet can be particularly small when the Young's modulus ratio of [a' is as described above, and that variations in the flying height can also be stabilized.

Therefore, in order to obtain a sheet that has stable output over high to low temperatures and has a long life, it is necessary to reduce the temperature change in the flying height.

Therefore, it is necessary to reduce the temperature change in the Young's modulus of the magnetic sheet. In conventionally used magnetic sheets, relationships such as {a}, 'b', and {c} have not been studied, and in particular, in the case of {a-, the flying height is reduced,
Moreover, it had not been elucidated that it could be stabilized.

Therefore, since conventional magnetic sheets are manufactured without taking these points into consideration, EtqC/EzC has a value of 0.6 or less. From the above viewpoint, the present inventors have completed the following invention.

That is, the present invention provides a magnetic sheet in which a coated magnetic layer containing ferromagnetic fine powder and a binder as main components is provided on a non-magnetic flexible support, wherein the magnetic sheet has the following general formula (1).
A floating type, which satisfies the relationship of Young's modulus shown by and is characterized in that a gap is provided between the surface of the magnetic layer and the magnetic recording/reproducing head, and recording and reproduction are performed in a non-contact state at a constant flying height. magnetic sheet. (1) Vessel≧.

・8't℃〉50℃ However, in formula (1), E2oqC
is the Young's modulus of the magnetic sheet at 20qo (room temperature), E
t°C refers to the Young's modulus of the magnetic sheet at t°C.

The present invention will be explained in more detail below.

The Young's modulus of a magnetic sheet as used in the present invention refers to various combinations such as a support (base) with ten magnetic layers, a back layer with ten supports + magnetic layers, a magnetic layer with ten supports and ten magnetic layers (both sides recording and reproducing possible). The apparent Young's modulus of the sheet is 1. Type and thickness of support, 2. Type and thickness of magnetic layer, 3. E2ooC, Et°C, which varies depending on the type, thickness, etc. of the back layer, is the Young's modulus of the magnetic sheet at 200ot°C.
EtoC/E2. If the value of qC is small, as already mentioned, the flying height changes greatly with respect to temperature. Generally, the change in flying height only needs to be small, but the range that does not cause any practical problems is always 25% or less. For that purpose, Etoo/B2o℃ZO. It is necessary that the value be 8.
(...1/25). Et/E2oZO. 8 (generally, this value is 4.0 mm lower than 1.0), it is possible to increase the flying height by 25% or less.

Note that it is desirable that Eran/E2o be as close to 1.0 as possible. The absolute value of Young's modulus can be determined regardless of the size as long as the sheet is flexible. It is sufficient to satisfy 8. Generally speaking, the Eo/E number is almost always 1 or more, that is, 0.8 or more, as in the case of [c} mentioned above, so in the floating magnetic sheet, the above general formula (1) is used.
Conditions such as, that is, the ratio of Young's modulus Et/E arc is 0.8
If it is above, it becomes possible to obtain a sheet that is excellent against temperature changes.

The sheet of the present invention is effective at 000 to 80 qo, but 2
It is particularly effectively used in the range of 0oC to 65qC. This is because when the temperature exceeds 80q0, deformation occurs at the part where the magnetic sheet is attached to the magnetic recording/reproducing device, and the flying height decreases by 25%.
This is because it changes more than the above, which is undesirable. In the present invention, by combining the binder and support in the magnetic layer, for example, the magnetic layer is a thermosetting binder and the support is a plastic sheet, the Et/E ZO.
It becomes possible to satisfy the relationship 8. The shape of the magnetic sheet used in the present invention is usually donut-like, but may be elliptical, rectangular, square, or other irregular shapes as necessary.

When used in a donut shape, the outer diameter is generally 10 skins to 5 skins.
There are many 0 arcs, and the inner diameter is often 3 to 5 broadsides. The thickness of the magnetic layer of a magnetic sheet varies depending on its use, but is from 0.05 French to
There are many 10 mountains. The thickness of the supporting base used for the magnetic sheet is 3
There are many willows, and depending on the purpose they are used, ranging from extremely flexible to slightly elastic. The total thickness of the magnetic sheet is often from 3.05 mm to 1.001 mm. The magnetic materials, binders, supports, etc. used in these magnetic sheets include the following. The magnetic recording medium of the present invention is manufactured by applying a magnetic layer on a nonmagnetic support and drying it.

Regarding the manufacturing method of the magnetic paint used in the present invention,
-15, No. 39-26794, No. 43-186,
No. 47-28043, No. 47-28045, No. 47
No. 128046, No. 47-28048, No. 47-31
No. 445, No. 48-11162, No. 48-21331
No. 48-33683, Soviet Patent Specification 308
No. 033: U.S. Patent No. 2581414: U.S. Patent No. 285515
No. 6: No. 3240621: No. 3526598: No. 37
No. 28262: No. 3790407: No. 3836393
It is described in detail in the specification etc. The magnetic paints described in these documents mainly consist of ferromagnetic fine powder, binder, and coating solvent, and may also contain additives such as dispersants, lubricants, abrasives, and antistatic agents. As the ferromagnetic fine powder of the present invention, ferromagnetic iron oxide, ferromagnetic chromium dioxide, ferromagnetic alloy powder, etc. can be used.

The above ferromagnetic iron oxide is represented by the general formula Fe○×
The value is 1.33 mix x SI. 50 ferromagnetic iron oxides, namely maghemite (y-Fe203, x=1.
50, magnetite (Fe304, x=1.33) and their bertolide compounds (Fe0×, 1.33<x
*1.50).

The above x value is X = red ox {2x (abmiC of divalent iron
%)+3×(mic% of a of trivalent iron)}.

A divalent metal may be added to these ferromagnetic iron oxides.

Divalent metals include Cr, Mn, Co, Ni, Cu, Z
n, etc., and mjc% of 0 to 1 melon to the above iron oxide
It is added within the range of

The above ferromagnetic chromium dioxide is 002 and Na,
K, Ti, V, Mn, Fe, Co, Ni, Tc, Ru,
0 to 2 metals such as Sn, Ce, and Pb, semiconductors such as P, Sb, and Te, or oxides of these metals. t% doped Cr02 is used. It is effective that the acicular ratio of the ferromagnetic iron oxide and ferromagnetic chromium dioxide is about 2/1 to 20/1, preferably 5/1 or more, and the average length is about 0.2 to 2.0 ridges. The above ferromagnetic alloy powder has a metal content of 75wt. % or more, and the metal content is 8 skin t. % or more of at least one ferromagnetic metal (i.e. F
e, Co, Ni, Fe, Co, Fe-Ni, -Co-N
j or Co-Ni-Fe), and the metal content is t.
% or less, preferably 0.5-5M. % is AI
, Si, S, SC, Ti, V, Cr, Mn, Cu, Zn
, Y, Mo, Rh, Pd, Ag, Sn, Sb, Te, Europe, Ta, W, Re, Au, Hg, Pb, Bi, La, C
It has a composition of e, Pr, Nd, B, P, etc., and may also contain a small amount of water, hydroxide, or oxide.

The above-mentioned ferromagnetic alloy powder is a particle having a major axis of about 0.5 mm or less.

Specifically, Special Publication No. 36-5515, No. 37-482
No. 5, No. 39-500, No. 39-10307, No. 44-14090, No. 45-18372, No. 47-22062, No. 47-22513, No. 46-284
No. 66, No. 46-38755, No. 47-4286,
No. 47-12422, No. 47-17284, No. 47
-1850 shout number, 47-18573, 48-39
No. 639, U.S. Patent No. 3026215: 3031
No. 341: No. 3100194: No. 3242005:
No. 3389014, British Patent No. 75265y: 782
No. 762: No. 1007323: French patent 1107
No. 654: Described in West German Published Patent Application (OB) No. 1281334.

As the binder used in the present invention, conventionally known thermoplastic resins, thermoplastic resins, reactive resins, and mixtures thereof are used. As a thermoplastic resin, the softening temperature is 150
Below C, the average molecular weight is 10,000 to 200,000
, with a polymerization degree of about 200 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, ester acrylate styrene copolymer, ester methacrylate acrylonitrile copolymer, ester methacrylate vinylidene chloride copolymer, ester styrene methacrylate copolymer, urethane elastomer, polyfluoride vinyl chloride, pinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer, polyamide resin, polyvinyl butyral,
Cellulose derivatives (cellulose acetate butyrate,
cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.),
Styrene-butadiene copolymers, polyester resins, various synthetic rubber-based thermoplastic resins (volibutadiene, polychloroprene, styrene-butadiene copolymers, etc.), and mixtures thereof are used.

Examples of these resins are given in Japanese Patent Publication Nos. 37-6877 and 39
No. 112528, No. 39-19282, No. 40-53
No. 4y, No. 40-20907, No. 41-9463, No. 41-1405, No. 41-16985, No. 4
No. 2-6428, No. 42-11621, No. 43-46
No. 23, No. 43-15206, No. 44-288,
44-17947, 44-18232, 45
-14020, 45-1450, 47-18
No. 573, No. 47-2063, No. 47-22064, No. 47-22068, No. 47-22069, No. 4
No. 7-12207, No. 48-27886, U.S. Patent No. 3144352: No. 3419420: No. 3499
No. 789: Described in the specification of No. 3713887.

As a thermoplastic resin or a reactive resin, it has a molecular weight of 200,000 or less in the state of a coating solution, but when added after coating and 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, for example, phenol/formalin nopolac resin, phenol/formalin-resol resin, phenol/furfural resin, xylene/formaldehyde resin, urea resin, melamine resin, drying oil-modified alkyd resin, carbonic acid resin-modified alkyd resin, malein. Acid resin modified alkyd resin, unsaturated polyester resin, epixy resin and curing agent (polyamine, acid anhydride, polyamide resin, etc.), terminal isocyanate polyester moisture curing resin, terminal isocyanate polyether moisture Curable resin, polyisocyanate polymer (1 obtained by reacting diisocyanate and low molecular weight triol)
Compounds having 3 or more isocyanate groups in the molecule,
diisocyanate trimers and tetramers), polyisocyanate prepolymers and resins containing active hydrogen (polyester polyols, polyether polyols, acrylic acid copolymers, maleic acid copolymers, 2-hydroxyethyl methacrylate copolymers, hydroxystyrene copolymers, etc.), and mixtures thereof.
Examples of these resins are given in Japanese Patent Publication Nos. 39-8103 and 40.
-977 Plan, No. 41-7192, No. 41-8016
No. 41-14275, No. 42-1817, No. 43-12081, No. 44-28023, No. 45-
No. 14501, No. 45-24902, No. 46-131
No. 03, No. 47-22065, No. 47-22066, No. 47-22067, No. 47-22072, No. 4
No. 7-22073, No. 47-28045, No. 47-2
No. 8048, No. 47-28922, U.S. Patent No. 31
No. 44353: No. 3320090: No. 343751, No. 3597273, No. 3781210, No. 37
81211.

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 of the ferromagnetic powder to 8 parts of the binder by weight.
It is used in an amount of 10 to 200 parts by weight, preferably 10 to 200 parts by weight. In addition to the above-mentioned binder and fine ferromagnetic powder, additives such as a dispersant, a lubricant, an abrasive, and an antistatic agent may be added to the magnetic recording layer. The magnetic recording layer has
In addition to the aforementioned binder and ferromagnetic fine powder, additives such as a dispersant, a lubricant, an abrasive, an antistatic agent, etc. may be added.

Dispersants include cabrylic acid, capric acid, lauric acid,
Fatty acids with 12 to 18 carbon atoms (R, COO,
R, is an alkyl or alkenyl 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, Ba) of the above-mentioned fatty acid: the above-mentioned fatty acid Fluorine-containing compound of ester: the above fatty acid amide: polyalkylene oxide alkyl phosphate ester: lecithin: trialkyl polyolefin oxy quaternary ammonium salt (alkyl has 1 to 5 carbon atoms, olefin is ethylene, propylene, etc.)
:: etc. are used.

In addition, higher alcohols having one or more carbon atoms and sulfur/acid esters can also be used. These dispersants are added in an amount of 0.5 to 2 parts by weight based on 10 parts by weight of the binder. Regarding these, the special public
836 Plan, No. 44-17945, No. 48-7441
No. 48-15001, No. 48-15002, No. 48-16363, No. 50-4121, US Pat. No. 3,387,993: US Pat. As a lubricant, dialkyl polysiloxane (
alkyl has 1 to 5 carbon atoms) dialkoxypolysiloxane (alkoxy has 1 to 4 carbon atoms), monoalkylmonoalkoxypolysiloxane (alkyl has 1 to 5 carbon atoms, alkoxy has 1 to 4 carbon atoms), Silicone oils such as phenylpolysiloxane and fluoroalkylpolysiloxane (alkyl has 1 to 5 carbon atoms); Conductive fine powders such as graphite; Inorganic fine powders such as molybdenum disulfide and tungsten disulfide; polyethylene, polypropylene,
Plastic fine powder such as polyethylene vinyl chloride copolymer and polytetrafluoroethylene: Q-olefin polymer: Unsaturated aliphatic hydrocarbon that is liquid at room temperature (a compound in which an n-olefin double bond is bonded to the terminal carbon, (about 20 carbon atoms): Fatty acid esters consisting of a solid monobasic fatty acid having 12 to 2 carbon atoms and a -hydric alcohol having 3 to 12 carbon atoms, fluorocarbons, etc. 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, Hakama Kosho No. 34-12970y, No. 38-11033, No. 43
No. 123889, No. 46-40461, No. 47-15
No. 621, No. 47-18482, No. 47-28043
No. 47-30207, No. 47-32001, No. 48-7442, No. 49-14247, No. 50-5
No. 042, No. 52-14082, No. 52-18561
No., JP-A-52-8804, JP-A No. 52-49803,
No. 52-49804, No. 52-49805, No. 52
No. 1673, No. 52-70811, U.S. Patent No. 2
No. 654681: No. 3470021: No. 349223
No. 5: No. 3497411: No. 3523086: No. 3
No. 62576: No. 3630772: No. 363425
No. 3: No. 3642539: No. 3687725: No. 3
No. 996407: No. 4007313: No. 400731
No. 4: No. 4018967: No. 4018968 Specification: “IBM Technical Disclosme
Bulletin"Vol.9No.7, Page
779 (December 1966) “ELEKTR
ONIK” 1961, No. 12, Page 380. Materials commonly used as abrasives include fused alumina, silicon carbide, and chromium oxide (Cr20).
3) Corundum, artificial corundum, diamond, artificial diamond, pomegranate, emery (main components: corundum and magnetite), etc. are used. These abrasives have a Mohs hardness of 5 or more and an average particle size of 0.05 to 5 m, particularly preferably 0.1 to 2 m. These abrasives are added in an amount of 0.5 to 2 parts by weight based on 10 parts by weight of the binder. Regarding these, Special Publication No. 47-18572, No. 48-15003
No. 48-15004 (U.S. Pat. No. 3,617,378), No. 49-39402, No. 50-19401,
U.S. Patent No. 3007807: U.S. Patent No. 3041196: U.S. Patent No. 3
No. 293066: No. 3630910: No. 368772
No. 5: No. 4015042: British Patent No. 1145349: West German Patent (DT-PS) No. 853211: No. 11
It is described in the specification of No. 0100. Antistatic agents include conductive fine powder such as carbon black and carbon black graft polymer; natural surfactants such as saponin; nonionic surfactants such as alkylene oxide, glycerin, and glycidol; higher alkylamines; Cationic surfactants such as quaternary ammonium salts, pyridine and other heterocycles, phosphoniums or sulfoniums: Anionic surfactants containing acidic groups such as carboxylic acid, sulfonic acid, phosphoric acid, and sulfate ester groups; Ampholytic active agents such as amino acids, aminosulfonic acids, sulfuric acid or phosphoric acid esters of aminoalcohols, etc. are used.

The above conductive fine powder is 0.0% per 100 parts by weight of the binder.
2 to 20 parts by weight are added, while surfactants are added in the range of 0.1 to 1 part by weight.

Some of these surfactant compounds that can be used as antistatic agents are Japanese Patent Publications Nos. 46-2726, 47-24881, 47-26882, 48-15440, 4
No. 8-26761, Tokukan Sho 52-18561, No. 52
-38201 Publication, U.S. Patent No. 2271623, U.S. Patent No. 2
No. 240472, No. 2288226, No. 267612
No. 2, No. 2676924, No. 2676975, No. 2
No. 691566, No. 2727860, No. 273049
No. 8, No. 2742379, No. 2739891, No. 3
No. 068101, No. 3158484, No. 320125
No. 3, No. 3210191, No. 3294540, No. 3
No. 415649, No. 3441413, No. 344265
No. 4, No. 3475174, No. 3545974, West German Patent Publication (OB) No. 1942665, British Patent No. 10
Including No. 77317, 119845 patent specification, etc.
“Synthesis of surfactants and their applications” by Ryohei Oda et al. (Dan Shoten 196 Sanno edition): A.

M. Schwall & J. W. "Surface Active Agents" by IJ Bay (Interscience Publications, Inc. 1958 edition): J
．． P. "Encyclopedia of Surface Active Agents, Volume 2" by Sisley (Chemical Publications Company, 1964 edition): "Surfactant Handbook" No. 6 Sakaki (Sangyo Tosho Co., Ltd., December 20, 1964)
It is written in books such as Japan). These surfactants may be added alone or in combination.

Although these are used as antistatic agents, they are sometimes applied for other purposes, such as dispersion, improving magnetic properties, improving lubricity, and as coating aids. The recording layer is formed by dissolving the above-mentioned composition in an organic solvent, kneading, dispersing, coating on a nonmagnetic support, and drying.

A treatment for orienting the magnetic powder in the magnetic layer can be carried out after the magnetic layer is applied and before it is dried, and a surface smoothing treatment can also be carried out before and after drying.
Organic solvents used during coating include: ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, propanol, and butanol; methyl acetate, ethyl acetate, butyl acetate, tyl lactate, and acetic acid. Ester types such as glycol monoethyl ether: Glycol ether types such as ether, glycol dimethyl ether, glycomonoethyl ether, and dioxane: Tar types (aromatic hydrocarbons such as benzene, toluene, and xylene) ): Chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and dichlorobenzene can be selected and used for the upper and lower layers.

Materials for the support include polyesters such as polyethylene terephthalate and polyethylene-2,6 naphthalate, polyolefins such as polyethylene and polypropylene,
Cellulose diacetate, cellulose triacetate
and cellulose acetate. Cellulose derivatives such as thylate and cellulose acetate propionate, pinyl resins such as polyvinyl chloride and polyvinylidene chloride, and plastics such as polycarbonate, polyimide, and polyamideimide are used. These supports may be transparent or opaque depending on the intended use of the magnetic recording medium. The above support is used to prevent static electricity, prevent transfer, prevent wow and flutter, improve the strength of the magnetic recording medium, and make the pack surface matte.
may be coated with a so-called back coat.

This back layer is composed of at least one additive such as the above-mentioned lubricant, abrasive, and antistatic agent, and in some cases, a dispersant is kneaded with the above-mentioned binder and coating solvent to uniformly disperse these additives. A dispersed coating liquid is applied onto the back surface of the above-mentioned support and dried.

Either of the magnetic layer and the back layer may be provided on the support first. Preferred additives commonly used are carbon black, graphite, talc, Cr203,
These include Q-Fe2Q (red iron), silicone oil, etc., and the binder is preferably a thermoplastic resin or a reactive resin.

In the case of inorganic compound additives, it is approximately 30 to 85 wt. based on the total solid content of the back layer. %, preferably 40 to 8 skin t%, in the case of organic compound additives about 0.1 to 3 skin t%, preferably 0.2 to 2 skin t. % mixing ratio.

Further, the dry thickness can be arbitrarily selected within the range of about 0.5 to 50 mm depending on the total thickness, use, shape, purpose, etc. of the magnetic recording body. Regarding the above-mentioned back coats, for example, Tokuko Sho 52-13411, Sho 52-17401, Sho 50-150407, Sho 52-8005, Sho 52
No. 18006, No. 52-170033, No. 52-25
No. 603, No. 52-30403, No. 52-37405
No. 52-40303, No. 52-40304, No. 52-6268, No. 52-841y, No. 52-841y, No. 52-40304.
No. 2-13411, No. 52-17401, U.S. Patent No. 2804401, U.S. Patent No. 3293066, U.S. Patent No. 3617
No. 378, No. 3062676, No. 3734772,
No. 3476596, No. 2643048, No. 2803
No. 556, No. 2887462, No. 2923642,
No. 2997451, No. 3007892, No. 3041
No. 196, No. 311542, No. 3166 No. 8, No. 3761311, etc.

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

For kneading, the magnetic powder and each of the above-mentioned components are fed into the dough mixer 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 kneaded for a predetermined period of time to obtain a magnetic paint. Various types of kneading machines are used for kneading and dispersing magnetic coating liquids.

For example, two roll mill, three roll mill, ball mill,
Vebble mill, Thoron mill, sand grinder, Sze
gvarl attritor, high speed inveler disperser, high speed stone mill, high speed impact mill, disperser, kneader, high speed mixer, homogenizer, ultrasonic disperser, etc. The technology regarding kneading and dispersion is described by T. C. PATTON
Author “PaintFlowandPigmentDis
John Wiley (1964)
& Sons).

It is also described in US Pat. No. 2,581,414 and US Pat. No. 2,855,156. Methods for applying the magnetic recording layer onto 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 can be found in "Coating Engineering" published by Asakura Shoten, pp. 253-27-1' (March 2, 1972).
(Longyuki Xiang) is described in detail.

By such a method, the magnetic layer coated on the support is optionally treated to orient the magnetic powder in the layer as described above, 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 particular, in the present invention, it has been found that by subjecting the magnetic recording layer to surface smoothing treatment, a magnetic recording body with a smooth surface and excellent wear resistance can be obtained. This surface smoothing treatment is performed by smoothing treatment before drying or calendering treatment after drying. The orientation treatment is performed under the following conditions. The orientation magnetic field is approximately 500 to 2 in alternating current or direct current.
000 Gauss.

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: No. 347396 No. 3681138
Specification: Japanese Patent Publication No. 32-3427: No. 39-2836
No. 8: No. 40-123624: No. 40-123625:
No. 41-13181: No. 48-13043: No. 48
Publication No. 139722, etc.

The drying temperature of the magnetic layer is about 50 to 100 oC, preferably 70 to 100 oC, particularly preferably 80 to 9000 oC, the air flow rate is 1 to 1/2, preferably 2 to 1/2, and the drying time is about 3 Existing sand ~10 minutes, preferably 1 ~
It's 5 minutes. To smoothen the surface of the coating film before drying the magnetic layer, methods such as a magnetic smoother, smoothing coil, smoothing blade, smoothing plunket, etc. are used as necessary. These are Special Publication No. 47-38802, No. 48-11336,
JP-A-49-53631, JP-A No. 52-112005,
Publication No. 51-777303, British Patent No. 1191424
It is shown in the specification etc. After drying the magnetic layer, the surface of the coating film is preferably calendered by a supercalendering method in which the coating is passed between two rolls, such as a metal roll and a cotton roll or a synthetic resin (eg, nylon) roll.

Super car. The conditions of the render are an inter-roll pressure of about 25-50 k9/arc, a temperature of about 35-150 qo, and a 5-1
20m/min. It is preferable to carry out the processing at a processing speed of . Temperature and pressure above these upper limits have an adverse effect on the magnetic layer and non-magnetic support. Also, the processing speed is about 5w/m
in. If it is less than 12%, the effect of surface smoothing will not be obtained.
0/min. If it is more than that, the processing operation becomes difficult. Regarding these surface smoothing treatments, see US Pat. No. 2,688,567, US Pat. No. 2,998,325, US Pat.
No. 3631, No. 50-10337, No. 50-9950
No. 6, No. 51-92606, No. 51-102049, No. 51-103404, and Japanese Patent Publication No. 17404/1983.

The present invention will be explained in more detail below using Examples and Comparative Examples. It will be readily understood by those skilled in the art that the ingredients, proportions, order of operations, etc. shown herein are subject to change without departing from the spirit of the invention. Therefore, the invention should not be limited to the examples below. In addition, in the following Examples and Comparative Examples, all parts indicate parts by weight. Example 1 A magnetic layer having the following composition was coated to a thickness of 3.0 mm on a support made of double-stretched PET with a thickness of 22 mm.

Coating composition (1) Magnetic material (yFe203 size 0.10 x 0.7 blur) HC: 26K 3009 Nitrocellulose (nitrogen content 11.2-12.3% polymerization degree 550) 21.5 poly Vinyl chloride vinylidene chloride copolymer copolymerization ratio = 7:3 Degree of polymerization = 400
)．・・・． 4.6 evening Epoxy resin (reaction product of bisphenol A and epichlorohydrin, molecular weight = 900, epoxy equivalent = 460-520, hydroxyl group content = 0.29%, Shell Oil Co. Epicote 1001)... 20th evening. silicone oil (
dimethylpolysiloxane)
...0.52 Soy lecithin...
...1.0 yen/alumina oxide (average particle size 4r)
). ...4.5 minutes Carbon black (average particle size 2mm). ．． ．． ．． ．． ．． 15th evening・
Isocyanate compound (75M% ethyl acetate solution of the reaction product of 3 moles of 2,4-tolylene diisocyanate compound and 1 mole of trimethylolbropane, BAYER's Desmod mL-75)...2
5.Butyl acetate・・・・・・1
After applying 200cc, the surface was polished, and then the outer diameter was 21.
00, and processed into a sheet shape with an inner diameter of 200.

The recorders whose characteristics of this sheet were checked are as follows.

The rotation speed is 360 pm, the head position is set at 1600 pm from the center, and the head shape is set in the middle of the head as shown in the attached figure.
a. 54, length {b'4.6 side, the surface in contact with the sheet forms part of a spherical surface with C=20R. Regarding the method and amount of head protrusion, the head was made to protrude about 250 mm from the back plate. A sheet was set in this recorder, and the characteristics of 690 of 20oo were measured.

The results are shown in the table below (sample No. 1001). In addition,
To measure Young's modulus at 2000 and 65q0, respectively,
The above-mentioned coated product was subjected to a hive test at 20o/6500 with a medium diameter of 12.65 ribs and a length of 30 tongs, and the Young's modulus of each product was determined from the load elongation diagram.

Example 2 A polyimide film having a thickness of 22 layers was used as a support, and a magnetic layer having the following composition was coated to a thickness of 4 layers.

Coating composition (b) ・Magnetic village (CrQ size 0.7 Buddha x 0.06 Buddha ◇) Hc
48e 300% vinyl chloride-vinyl acetate copolymer (copolymerization ratio = 87:1 Marugame degree 380).・・・．・-10 days・Polyester polyurethane (reaction product of polyester with terminal hydroxyl groups consisting of butane diol and adipic acid and 2,4-diphenylmethane diisocyanate, molecular weight approximately 4 sides) ……24.5 days・Carbon black (Average particle size 2 French).・・・．・・１
6. Silicone oil (dimethyl polysiloxane)...
0.8 chromium oxide (Cr203 average particle size 5r
).・・・． ...5.7 polyisocyanate compound (75M% ethyl acetate solution of reaction product of 3 moles of 2,4-tolylene diisocyanate compound and 1 mole of trimethylolpropane) ...18.4 polyisocyanate compound
Methyl ethyl ketone...40
0cc・Butyl acetate・・・・・・
- 800cc and all other settings were the same as in Example 1, and the test results are shown in 2001.

Example 3 The same test as in Example 1 was conducted except that the coating thickness was increased by 7 mm.

The results are shown in 3001. Example 4 The same test as in Example 22 was conducted except that the coating thickness was increased by 7 mu in Example 2. The results are shown in 4001. Example 5 Using PET (reinforced base which was further re-stretched after biaxial stretching) with a thickness of 36 mm as a support, magnetic layers having the following compositions were coated to a thickness of 3 mm and 7 mm, respectively. Coating composition (m)・Magnetic material (y-Fe2Q, H
c26 e, size: 0.6 French x 0.08 mm 0)
300% vinyl chloride vinylidene chloride copolymer (copolymerization ratio = 7:3, degree of polymerization = 400).・・・． ...20th night Epoxy resin (reaction product of bisphenol A and epichlorohydrin, molecular weight = 900, epoxy equivalent = 460-520, hydroxyl group content = 0.29% Shell Oil Co. Epicoat 1001). ．．・．． ．．・41.6 evening ・Silicone oil (dimethylpolysiloxane)...1.2
Chromium oxide (Cr203, average particle size 5)
・・・・・・12 evening・Isocyanate compound (75M% ethyl acetate solution of the reaction product of 3 moles of 2,4-tolylene diisocyanate compound and 1 mole of trimethylolpropane) Desm m of Bayer A.○. L-75) ...16.
4.Butyl acetate・・・・・・1
After applying 200cc, perform surface polishing, and then reduce the outer diameter to 1
800, and processed into a sheet with an inner diameter of 25.40.

The recorders on which this sheet was tested are:

・36 pm ・Head position: 1450 from the center ・Head shape: 0.3 side length in the head 1.2 The surface in contact with the rib sheet is a part of the 4-ball 2-spherical surface ・Head protrusion method and amount Approximately from the back plate It protruded by 350 Buddhas.

The results for a coating thickness of 3mm are shown in 5001, and the results for a coating thickness of 7mm are shown in 5002.

In addition, when examining head wear after the life tests of Examples 1 to 5, both 3001 and 5002 were found to be at low temperatures (50
0) had more than 15 Buddhas.

Head wear in all tests under other conditions was less than 2 French. Todoroki Sondo Snow Cloud Table Cloud Place) Liaoning Kashi-type Drop Heavy Denun R3 Kameyari High 3's Chopstickboard Kashi.

So . Snow clouds and cranes Katsukainada Beach Saint Shizukube Q vine sheep Thigh ;be [Q Air Force” Hina Ant plate kiren.

QQ Shizuku Kaseigun Message .

N) Sya Kijumine snow erosion Lotus S Hataki Uravine Royal Words [Hatake N Boku] N Turtle [N Eel-pierced cerebral sulcus ÷ku.

It's a busy day L Bell Et of the present invention.

/E2. 〇 is 0. The support sheet has the following characteristics. 1. Long sheet life, especially at high temperatures.

2 D・0 is low, especially at high temperatures.

3 Enbe, especially at high temperatures.

The tube is good. 4 Good resolution, especially at high temperatures.

5 The characteristics should be stable between 5 and 6500.

The present invention includes the embodiments shown below. 'i'
In the general formula (1) of the claims, t°C=65q
0 and E650C/E2.

〇CZO. 8. A floating magnetic sheet characterized by having the following characteristics: [ii} A magnetic sheet characterized in that the general formula (1) in the claims is the following general formula (0).

(.

)・＞Toyomi≧o-8, t℃＞5o℃'iii' In the claims and general formula (1) of {ii) above, 5
A floating magnetic sheet characterized in that 000<t°C<800°.

{iv} A floating magnetic sheet according to the claims, characterized in that the magnetic sheet has a flying height from the surface of a magnetic head of 0.01 to loAm.

M A levitated magnetic sheet characterized in that the change in flying height in (iv) above is within 25%.

M} A floating magnetic sheet according to the claims, characterized in that the total thickness of the non-magnetic flexible support and the magnetic layer is 3.05 mm to 1.001 mm.

Kite In ~i' above, the levitated magnetic material is characterized in that the thickness of the non-magnetic flexible support is 3 mm to 1 mm, and the thickness of the magnetic layer is 0.05 mm to 100 mm. sheet. A floating magnetic sheet according to the claims, characterized in that a back layer is provided on the surface of a non-magnetic flexible support opposite to the magnetic layer.

Wind A floating magnetic sheet characterized in that the thickness of the back layer on the above side is 1 mm to 5 Am.

{x' In the claims, a floating magnetic sheet characterized in that a magnetic layer is further provided on the surface of the non-magnetic flexible support opposite to the magnetic layer.

(xi) In the above 'x}, the thickness of the magnetic layer is 0.0
A levitated magnetic sheet characterized by a skin of 5 Buddhas to 100 Buddhas.

[Brief explanation of drawings]

The attached drawing shows the shape of the head of a recorder used to check the characteristics of the sheet of the present invention.

Claims (1)

[Scope of Claims] 1. A magnetic sheet in which a coated magnetic layer containing ferromagnetic fine powder and a binder as main components is provided on a support made of non-magnetic flexible plastic, wherein the magnetic sheet has the following general formula: A levitated magnetic sheet characterized by satisfying the Young's modulus relationship shown in (I). (I) (E_t℃)/(E_2_0℃≧0.8,t℃
>50℃) However, in formula (I), E_2_0℃ is 2
Young's modulus of magnetic sheet at 0°C (room temperature), E_t°C
represents the Young's modulus of the magnetic sheet at t°C.