JPH03278314A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To always obtain stable traveling durability even under severe conditions such as high temp. high humidity or low temp. low humidity and to prevent deterioration of characteristics of the medium by incorporating quater nary ammonium salt of specified phosphoric ester into a magnetic layer or into the surface of the magnetic layer. CONSTITUTION:The magnetic recording medium consists of a nonmagnetic supporting body and a magnetic layer formed thereon. The magnetic layer or the surface of the magnetic layer contains quaternary ammonium salt of phosphoric ester expressed by formulae I and/or II. By using the quaternary ammonium, ionic bond with the phosphoric ester can be increased, which signifi cantly suppresses dissociation of salt against changes in temp. and hyumidity. The ammonium salt itself has high melting point and gives solid lubricating effect, high adhesion property and good lubricating property in a wide temp. range. Thereby, when a binder containing polar groups is used as the binder for the coating type magnetic recording medium, the effect of the ammonium salt is significant. Thereby, the medium has stable traveling durability even under severe conditions such as high temp. high humidity or low temp. low humidity, and shows no deterioration in the characteristics during storage.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a magnetic recording medium having a magnetic layer on a non-magnetic support, and in particular to a magnetic recording medium that has excellent runnability and durability under a wide range of temperature and humidity conditions. It's about the medium.

[Prior Art and its Problems] In magnetic recording media, there is an increasing demand for higher density recording, and it is known that one way to meet this demand is to smooth the surface of the magnetic layer.

In addition, ferromagnetic thin film magnetic recording media are also being developed as next-generation media. As a result of the increase in the friction coefficient of the contact between the magnetic layer and the device during running, the magnetic layer of the magnetic recording medium tends to be damaged or peeled off after a short period of use.

In order to deal with such problems, methods are known in which a lubricant is added to the coating layer of the magnetic layer, or a method in which a lubricant is coated on the surface of the magnetic layer.

Conventionally, mineral oil, silicone oil, higher alcohol, higher fatty acid, fatty acid ester, beef tallow, whale oil, animal oil such as whale oil, or vegetable oil have been used as the lubricant.

If the amount of the conventional lubricant shown above is small, increasing the amount to enhance the lubrication effect (A) may weaken the mechanical strength of the magnetic coating (C), cracking the magnetic layer, causing shavings to contaminate the route, or causing insufficient In some cases, the durability of still playback could not be achieved. In order to improve the cavity durability of still regeneration, fatty acid esters such as butyl stearate and fatty acids such as myristic acid are mixed, as disclosed in Japanese Patent Publication No. 2B-28367 and Japanese Patent Publication No. 39081-1981. It is known to be used as However, when these disclosed examples are used, there is a drawback that friction increases when the magnetic tape is run under high temperature conditions, and the running tension of the magnetic tape increases.

When fatty acids are used alone, they are effective in improving image quality, but in order to obtain lubricity, it is necessary to use large amounts, which softens the magnetic layer and reduces its mechanical strength. However, there was a drawback that the durability of still replaying deteriorated.

Alkyl sulfate esters have been used as plasticizers for magnetic layers or as dispersants for magnetic paints, as disclosed in JP-A-52-7704.

It is true that adding phosphoric acid ester to the magnetic layer improves dispersibility and still durability to some extent, but the frictional force did not decrease.

Furthermore, the combined use of fatty acids and fatty acid ester compounds described in Japanese Patent Publication No. 5L39081 results in good still durability and relatively low tension, but 8
5! Under high temperature conditions such as RFI (relative humidity), running tension increases.

In order to eliminate these drawbacks, Japanese Patent Application Laid-Open No. 56-80828
The paper proposes the use of saturated or unsaturated fatty acids and aliphatic alkyl phosphates in the magnetic layer. This proposal states that it has excellent lubricity at room temperature and high temperature, and has good abrasion resistance and durability against still recirculation.

However, recently, as consumer flexible disk drive devices such as those for VTRs, personal computers, and word processors have become widespread,
The usage conditions for magnetic recording media have also become broader, such as use at low temperatures and use at high temperatures and high humidity. Therefore, magnetic recording media must be stable so that their running durability does not change even under various predicted conditions, but conventionally known lubricants are not sufficient. There was also the problem that performance deteriorated over time. Furthermore, Japanese Patent Laid-Open No. 11.2526 proposes a magnetic recording medium in which a tertiary amine salt of acidic phosphoric acid ester is deposited on a magnetic layer. This maintains its lubricating effect even under various usage conditions and for long periods of time, and has excellent running performance and durability, but the μ value tends to increase at low temperatures and low humidity, and at high temperatures and high humidity. , especially 50″C9
After storage for one week at 0x, the μ value further increased, indicating that the storage stability was insufficient.

In addition, as another measure to improve the running durability, a method of adding abrasives (hard particles) to the magnetic layer has been proposed and implemented. Unless a considerable amount of abrasive is added to the material, the effect of the addition is unlikely to appear.

That is, it is ultimately difficult to obtain running durability without sacrificing electromagnetic conversion characteristics and head wear resistance.

Therefore, in order to solve the above problem, the present inventors conducted intensive studies on the history of lubricants from the viewpoint of binders, and found that by using a quaternary ammonium salt of a phosphoric acid ester with a specific structure, An improvement effect on the above-mentioned problem could be found, leading to the present invention.

[Purpose of the invention]

That is, the purpose of the present invention is to provide a magnetic recording medium that can always provide stable running durability even when used under harsh conditions such as high temperature, high temperature, low temperature and low humidity, and whose characteristics do not deteriorate due to storage. be.

[Means for solving problems]

An object of the present invention is to provide a magnetic recording medium having a magnetic layer on a non-magnetic support, in which a quaternary phosphate ester represented by the following general formula 1 and/or general formula 2 is added in the magnetic layer or on the surface of the magnetic layer. This is achieved by a magnetic recording medium characterized by containing a class ammonium salt.

(General Formula 2) (However, in the formula, R and Ro represent the same or different hydrocarbon groups having 10 to 26 carbon atoms, and Mon represents 0 or an integer of 2. (R" represents the same or different hydrocarbon groups.) A quaternary ammonium salt of a phosphoric acid ester represented by the general formula 1 and/or the general formula 2 used in the present invention (hereinafter abbreviated as the compound of the present invention). In addition, when referring only to the quaternary ammonium salt of the phosphoric acid ester represented by the general formula 1, it is referred to as the compound 1 of the present invention.
and, when referring only to the quaternary ammonium salt of the phosphoric acid ester represented by the general formula 2, they are respectively referred to as the compound 2 of the present invention. ) has the drawbacks of conventional tertiary amine salts of acidic phosphoric acid esters (i.e., salts of an anionic component of a phosphoric ester and a cationic component that is ammonium consisting of a tertiary amine and a proton). , the dissociation of the salt is promoted, resulting in an increase in the component that has lost charge, so stability is based on the interaction of the salt with the binder, ferromagnetic powder, etc. in the magnetic layer, such as electrostatic attraction force. This is used to eliminate the drawback that lubricating performance deteriorates.

That is, by employing the quaternary ammonium, the compound of the present invention has significantly improved ionic bonding with the phosphoric acid ester compared to the conventional ammonium salt, and as a result,
It was possible to significantly suppress the dissociation of the salt against changes in temperature and humidity.

The compound of the present invention has good affinity with inorganic materials, adheres to the surface of metal materials, and is easily oriented. Further, the compound of the present invention itself has a high melting point, has a solid lubricating function, has a high degree of fixation, and exhibits good lubricating performance even in a wide temperature range.

Further, the compound of the present invention exhibits remarkable effects particularly when a polar group-containing binder is used as a binder for a coated magnetic recording medium. because,
This is because the compound of the present invention interacts with the polar group of the binder and has a salt-like property that is difficult to dissociate so as to maintain its lubricating performance indefinitely due to the anchor effect. As a result, the anion form of the phosphate ester, the cation form of the quaternary ammonium ion, and the anion form and cation form of the polar group of the binder are strongly adsorbed, so it can be used under harsh conditions such as high temperature, low temperature, and low humidity. Even when used, stable running durability is always obtained, and its characteristics do not seem to deteriorate during storage.

That is, it is considered that the quaternary ammonium of the cationic compound of the compound of the present invention interacts with the binder to cause the phosphoric acid ester, which is the anionic compound, to stably exist on the surface. Among these quaternary ammoniums, quaternary ammonium, which has an unsubstituted hydrocarbon group with strong basicity, strongly interacts with phosphate ester, which is an anion base, and makes it easier to orient, so it has a remarkable effect on slipperiness. It seems that there is.

R and Ro of the phosphoric acid ester moiety which is an anion base of the compound of the present invention are hydrocarbon groups having 10 to 26 carbon atoms, and are selected regardless of molecular weight, molecular structure, unsaturated bond, and isomer structure. However, non-aromatic hydrocarbon groups (however, aralkyl groups and the like are included) are preferred, and straight-chain alkyl groups are particularly preferred.

In this case, if the number of carbon atoms is 9 or less or 27 or more, the hydrophobic group is too short or too long, resulting in a decrease in orientation on the magnetic layer or an increase in the coefficient of friction, which is not preferable.

R of quaternary ammonium which is a cationic compound of the present invention
1, R2, R3, and R4 are also hydrocarbon groups, but these have different molecular weights, molecular structures,
Although it can be selected regardless of the unsaturated bond or isomer structure, a non-aromatic hydrocarbon group having 1 or more and 26 or less carbon atoms is preferred, and a straight-chain alkyl group is particularly preferred.

In this case, furthermore, among the combinations based on the difference in the number of carbon atoms of RI and R4, one of RI and R4 has a carbon number of 1.
0 to 26 alkyl groups, the remaining 3 groups are methyl groups,
It is said that an alkyl group having 1 to 4 carbon atoms such as an ethyl group, or an alkyl group having 4 or less carbon atoms in each of the hydrocarbon groups R1, R2, Ri, and R' orients the hydrophobic chain. Desirable from this point of view.

In the magnetic layer of the present invention, the binder that coexists with the compound of the present invention means a resin made of various polymers known in the industry, and the binder coexists with the compound of the present invention in which the ferromagnetic powder and the compound of the present invention are dispersed.
Although there is no particular limitation as long as the binder is retained, in the present invention, it is particularly preferable that the binder contains at least one type of resin having a polar group in order to exhibit the above-mentioned effects.

The polar group is not particularly limited as long as it can interact with the quaternary ammonium such as electrostatic attraction, or it can be induced by chemical reaction etc. For example, -0) 1 group, -
C00M group, -503M group, O5OfM group, -103
M2 group, -NR2' group, -N#IR3bC1A group (however, the group is hydrogen, an alkali metal, or ammonium, and when there are multiple 1s in one group, they may be the same or different from each other. R5 and R6 represents hydrogen or an alkyl group, and K represents a halogen atom), an epoxy group, and the like. These polar groups can be introduced into existing polymers, or a polar group-containing polymer can be synthesized using monomers containing the polar groups.

The amount of the polar group present in the binder can be selected from the range of 101 to 10-3 equivalents per gram of binder.

If it is less than lo-7 equivalent, the coefficient of friction will increase, which is undesirable, and if it is more than 10-3 equivalent, the viscosity of the magnetic coating liquid obtained by cross-dispersion with ferromagnetic powder will increase, and the dispersibility of ferromagnetic powder will decrease. This is not preferable because the coefficient of friction decreases and the coefficient of friction also increases.

The above adjustment of the amount of polar groups present is carried out in accordance with the adjustment of the addition of the compound of the present invention, but it may be carried out using only a polar group-containing polymer, or in addition, it may be carried out using a polymer containing no polar groups. It may be used in combination with a polymer. in this case,
The number of polar groups contained per molecule of the polar group-containing polymer, the type thereof, the skeletal structure of the polymer, etc., the amount of the polar group-containing polymer added, the type of polymer that does not contain polar groups and the amount added, ferromagnetic powder It is recommended to consider the type and amount of addition.

In particular, in the present invention, the polar group-containing polymer is preferably composed of one or more types of polymers that account for 5% by weight or more in the composition of the type of polymers constituting the binder.

A magnetic recording medium having a magnetic layer to which the compound of the present invention can be applied is one in which a magnetic layer is formed by dissolving the binder in an organic solvent and coating it on a non-magnetic support (hereinafter referred to as a coated magnetic recording medium). ), as well as those in which a magnetic layer is provided on a non-magnetic support by vapor deposition (hereinafter abbreviated as metal thin film type magnetic recording media); Known materials can be used, and there are no particular limitations, including materials in which the surface of the metal thin film is physically or chemically treated.

The amount of the compound of the present invention to be added to the coated magnetic recording medium is appropriately selected depending on the type and amount of the binder resin used, the polar group, the ferromagnetic powder, etc.; The amount added to the metal thin film type magnetic recording medium can be appropriately selected depending on the condition of the metal thin film surface, and is usually selected from the following range.

Methods for retaining the compound of the present invention in the magnetic layer include adding it to the magnetic layer, topcoating the surface (dissolving the material in an organic solvent and coating or spraying it on the substrate, and then drying it, and melting the material). There are two methods: a method in which the material is applied to the substrate by immersing the material in an organic solvent solution, a method in which the material is adsorbed to the surface of the substrate by immersing the material in a solution prepared by dissolving the material in an organic solvent, and a method in which the material is adsorbed onto the surface of the substrate, and a method using the Langmuir-Blodgett method, etc.

When the compound of the present invention is added to the magnetic layer of a coated magnetic recording medium, it is suitably added in an amount of 0.1 to 8% by weight based on the ferromagnetic powder. The top coat on the surface of the magnetic layer is 0.5~100■
/A is appropriate, and in the case of a magnetic layer of a coated magnetic recording medium,
2 to 50 ■/bo in the case of metal thin film magnetic recording media,
Particularly suitable is 2 to 30 .mu./bo.

If the amount used exceeds this range, the compound of the present invention will be present in excess on the surface, which may not only cause problems such as sticking and moisture absorption, but also cause damage to the magnetic layer when added to the magnetic layer. However, due to the action of plasticizing the binder, there are problems such as a decrease in durability.

If the amount used is below this range, the surface amount will be insufficient and no effect will be obtained.

Specifically, the compounds of the present invention include the following compounds.

The above-exemplified compounds of the present invention can be obtained by, for example, reacting the metal salt of the phosphoric acid ester (Na, Pb, Ag, etc.) with the quaternary ammonium chloride in a mixed solvent of alcohol and water, and then reacting the compound with an organic solvent. It can be obtained by recrystallization.

In the present invention, other lubricants may be mixed.

Lubricants that can be used in combination include saturated and unsaturated fatty acids (myristic acid, stearic acid, oleic acid, etc.) and their metal soaps, N-substituted and unsubstituted fatty acid amides, fatty acid esters (including various monoesters, sorbitan, fatty acid esters of polyhydric esters such as glycerin, esters of polybasic acids, etc.), ester compounds with ether bonds,
Higher aliphatic alcohols, monoalkyl phosphates,
Trialkyl phosphate, paraffins, silicone oil, fatty acid-modified silicone oil, animal and vegetable oils, mineral oil, higher aliphatic amines; graphite, silica, boric nitride, graphite fluoride, calcium carbonate, barium sulfate, molybdenum disulfide, tungsten disulfide Inorganic fine powder such as polyethylene, polypropylene, polyvinyl chloride, ethylene-
Polymer powders such as vinyl chloride copolymers, polyolefin or α-olefin resin powders such as polytetrafluoroethylene, melamine resin fine powders, and polyimide resin fine powders; unsaturated aliphatic hydrocarbons that are liquid at room temperature, terminal modification or unmodified perfluoroalkyl polyether,
Examples include fluorocarbons.

The preferred usage amount of these mixed lubricants varies depending on the mode of use, but is generally 0.1 times to 0.1 times the amount of the compound of the present invention.
This is twice the usage amount.

As the binder used in the present invention, known thermoplastic resins, thermosetting resins, radiation-curable resins, reactive resins, and mixtures thereof, which have been conventionally used as binders for magnetic recording media, can be used. I can do it.

The glass transition temperature (Tg) of the above resin is -40°C to 15
0°C1 weight average molecular weight is 10,000 to 300,000, preferably 1
10,000~】00,000.

Examples of the thermoplastic resin include vinyl chloride/vinyl acetate copolymer, vinyl chloride, vinyl acetate and vinyl alcohol,
Copolymers with maleic acid and/or acrylic acid, vinyl copolymers such as vinyl chloride/vinylidene chloride copolymers, vinyl chloride/acrylonitrile copolymers, ethylene/vinyl acetate copolymers, nitrocellulose, cellulose acetate Propionate, cellulose derivatives such as cellulose acetate butyrate resin, allyl resin, polyvinyl acetal resin, polyvinyl butyral resin,
Rubber resins such as polyester polyurethane resin, polyether polyurethane, polycarbonate polyurethane resin, polyester resin, polyether resin, polyamide resin, amino resin, styrene butadiene resin, butadiene acrylonitrile resin, silicone resin, fluorine resin, etc. can be mentioned.

Among these, vinyl chloride resin is preferred because it has high dispersibility of ferromagnetic powder.

The above-mentioned thermosetting resin or reactive resin is one whose molecular weight becomes extremely large when heated, such as phenol resin, phenoxy resin, epoxy resin, curable polyurethane resin, urea resin, melamine resin, alkyd resin, silicone resin. , acrylic reactive resins, epoxy-polyamide resins, nitrocellulose melamine resins, mixtures of high molecular weight polyester resins and isocyanate prepolymers, mixtures of methacrylate copolymers and diisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea These include formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/polyisocyanates such as triphenylmethane triisocyanate, polyamine resins, polyimine resins, and mixtures thereof.

The radiation-curable resin used is one in which a group having a carbon-carbon unsaturated bond is bonded to the thermoplastic resin as a radiation-curable functional group. Preferred functional groups include acryloyl and methacryloyl groups.

In the binder molecules listed above, -OH group, -C00M group,
-5OffM group, -0SOffM group, -PO3Mg group,
-NR,' group, N@Rff6C1θ group (however, h is hydrogen, an alkali metal, or ammonium, and when there is a plurality of h in one group, they may be the same or different from each other.

R5 and R6 represent hydrogen or an alkyl group. Also, X
indicates a halogen atom. ) or into which a polar group such as an epoxy group is introduced is preferable from the viewpoint of improving the dispersibility and durability of the ferromagnetic powder, and the effect of adding the compound of the present invention is noticeable. The content of the polar group is preferably in the range of 10"' to 10-' equivalents, more preferably in the range of 10-6 to 10-4 equivalents, per gram of the polar group-containing polymer.

The polymer binders listed above may be used alone or in combination, and can be cured by adding a known isocyanate-based crosslinking agent and/or a radiation-curable vinyl monomer.

The isocyanate crosslinking agent is a polyisocyanate compound having two or more isocyanate groups, for example,
Tolylene diisocyanate], 4゜4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, naphthylene-1,5
Examples include isocyanates such as -diisocyanate, o-toluidine diisocyanate, isophorone diisocyanate, and triphenylmethane triisocyanate, products of these isocyanates and polyalcohols, and polyisocyanates produced by condensation of these isocyanates. These polyisocyanates are Coronate from Nippon Polyurethane Kogyo ■, Coronate HL, Coronate H, Coronate EH, Coronate 2.
014, Coronate 2030, Coronate 2031, Coronate-1-2036, Coronate 3015, Coronate 3040, Coronate 3041, Millionate MR, Millionate MTL, Daltosec 1350, Daltosec 2170, Daltosec 2280, Takenate D102, Takenate DIION from Narita Pharmaceutical ■ Takenate Product names such as D200, Takene) D202, Sumidur N75 from Bayer ■, Desmodule IL, Desmodule N, Desmodule HL from West German Bayer, Burnock D850, Parnock D802 from Dainippon Ink & Chemicals ■ It is commercially available at.

Radiation-cured vinyl yarn threads are compounds that can be polymerized by radiation irradiation and have one or more carbon-carbon unsaturated bonds in the molecule, such as (meth)acrylic esters and (meth)acrylamide. , allyl compounds, vinyl ethers, vinyl esters, vinyl X
[Compounds include N-vinyl compounds, styrene, (meth)acrylic acid, crotonic acid, itaconic acid, olefins, etc. Among these, preferred are (meth)acrylates of polyethylene glycol, such as diethylene glycol di(meth)acrylate, which have two or more (meth)acryloyl groups, trimethylolpropane tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate. Examples include acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and a reaction product of a polyisocyanate and a hydroxy(meth)acrylate compound.

These crosslinkers account for 5 to 45% of the total binder including crosslinkers.
Preferably, it is weight percent (wt%).

The total amount of the binder (including crosslinking agent) of the present invention is 10 to 4 QwL%, preferably 15 to 30%, based on the ferromagnetic powder.
It is wt%. If the blending ratio of the binder is more than the above range, the packed layer of ferromagnetic powder will be poor and the electromagnetic characteristics will be deteriorated, whereas if it is less, the running durability will be decreased.

As the ferromagnetic powder used in the present invention, ferromagnetic iron oxide powder, CO-doped ferromagnetic iron oxide powder, ferromagnetic chromium dioxide powder, ferromagnetic metal powder, ferromagnetic alloy powder, barium ferrite, etc. can be used.

Examples of ferromagnetic alloy powders include 75% by weight or more of metals, and 80% by weight or more of metals by at least 1% by weight of metals.
types of ferromagnetic metals or alloys (e.g. Fe, Co, Ni
, Fe-Co, Fe-Ni, Co-Ni, Co-Fe-
Ni, etc., and other components (e.g., AI, Si, S, Sc, Ti, ■, Cr, Mn
, Cu, Zn, Y, , Mo, Rh, Pd, Ag, , Sn
, Sb.

B, Ba, Ta, W, Re, Au, Hg, Pb.

P, La, CeXPr, Nd, Te, Bi, etc.). Further, the ferromagnetic metal may contain a small amount of water, hydroxide, or oxide.

Methods for producing these ferromagnetic powders are known, and the ferromagnetic powder used in the present invention can also be produced according to known methods.

The shape and size of the ferromagnetic powder are not particularly limited and can be widely used. The shape may be needle-like, rice-grain-like, spherical, cubic, plate-like, etc., but needle-like and plate-like are preferable from the viewpoint of electromagnetic conversion characteristics. There are no particular restrictions on the crystallite size or specific surface area, but the crystallite size is 400 Å or less, and the S BET is 3.
0 is preferably 78 or more. The pH1 surface treatment of ferromagnetic powder can be used without any particular restrictions. The surface may be treated with a substance containing elements such as titanium, silicon, or aluminum, or treated with an organic compound such as an adsorbent compound having a nitrogen-containing heterocycle such as carboxylic acid, sulfonic acid, sulfuric acid ester, or benzotriazole. may be done. The preferred pl is 5
~10. In the case of ferromagnetic iron oxide powder, divalent iron/3
It can be used without any particular restriction on the ratio of iron to iron.

As the material of the non-magnetic support, polyesters such as polyethylene terephthalate and polyethylene 2,6-naphthalate; polyolefins such as polyethylene and polypropylene; cellulose derivatives such as cellulose triacetate; resins such as polycarbonate, polyimide, and polyimide amide may be used. If necessary, it may be metallized with a metal such as aluminum, or may be a metal foil such as aluminum foil or stainless steel foil.

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

The thickness of the support is preferably 3 to 100-1 for a magnetic tape, and preferably 3 to 20-1 for a magnetic disk, and 20 to 10 for a magnetic disk.
0- is the commonly used range.

The magnetic layer of the magnetic recording medium of the present invention preferably further contains inorganic particles having a Mohs hardness of 5 or more.

The inorganic particles used are not particularly limited as long as they have a Mohs hardness of 5 or more. Examples of inorganic particles having a Mohs hardness of 5 or more include A1□0. (Mohs hardness 9), ↑10 (Mohs hardness 6)
), Ti0z (6.5), Sing (7)
), Snug (6.5), CrzOz (9), and cr -FezO, (5.5), which can be used alone or in combination.

Particularly preferred are inorganic particles having a Mohs hardness of 8 or more. When inorganic particles with a Mohs hardness lower than 5 are used, the inorganic particles tend to fall off from the magnetic layer and have almost no abrasive action on the head, resulting in head clogging and poor running durability. Become.

The content of the inorganic particles is usually in the range of 0.1 to 20 parts by weight, preferably in the range of 1 to 10 parts by weight, based on 100 parts by weight of the ferromagnetic powder.

In addition to the above-mentioned inorganic particles, the magnetic layer preferably contains carbon blank (particularly one having an average particle size of 10 to 300 nanometers (10-9 m)).

Next, an example of a method for manufacturing the magnetic powder-coated magnetic recording medium of the present invention will be described.

First, the ferromagnetic powder, the binder, the compound of the present invention, and if necessary, other fillers, additives, etc. are kneaded with a solvent.
Prepare magnetic paint. As the solvent used during kneading, solvents commonly used for preparing magnetic paints can be used.

There is no particular restriction on the kneading method, and the order of addition of each component can be set as appropriate.

For example, fillers, additives, and crosslinking agents dissolved in an organic solvent can be prepared and added to a ferromagnetic powder dispersion prepared using a solvent, a binder, ferromagnetism, and the like.

When preparing a magnetic paint, known additives such as dispersants, antistatic agents, lubricants, etc. can also be used.

Examples of dispersants include fatty acids having 12 to 22 carbon atoms, salts or esters thereof, compounds in which part or all of the hydrogen atoms of these compounds are replaced with fluorine atoms, amides of the above fatty acids, aliphatic amines, and higher alcohols. , sarcosinates, alkyl ether esters, trialkyl polyolefins, oxyammonium salts and lecithin.

When using a dispersant, the ferromagnetic powder 1 usually used is
It is used in a range of 0.1 to 10 parts by weight per 00 parts by weight.

Examples of antistatic agents include conductive fine powders such as carbon black and carbon blank graft polymers; natural surfactants such as saponins; nonionic surfactants such as alkylene oxides, glycerins, and glycidols; higher alkyl amines. cationic surfactants such as quaternary ammonium salts, salts of pyridine and other heterocyclic compounds, phosphoniums or sulfoniums;
Anionic surfactants containing acidic groups such as carboxylic acid, phosphoric acid, sulfuric ester groups, and other phosphoric ester groups; Examples include amphoteric surfactants such as amino acids, aminosulfonic acids, and sulfuric or phosphoric esters of amino alcohols. be able to. When using the above conductive fine powder as an antistatic agent, for example, 0.1 parts by weight per 100 parts by weight of ferromagnetic powder.
It is used in a range of 10 parts by weight, and when a surfactant is used, it is also used in a range of 0.12 to 10 parts by weight.

Note that the above-mentioned additives such as dispersants, antistatic agents, and lubricants are not strictly limited to having only the above-mentioned effects; for example, if the dispersant is a lubricant, Alternatively, it may act as an antistatic agent. Therefore, it goes without saying that the effects of the compounds exemplified by the above classifications are not limited to those listed in the above classifications, and when using a substance that has multiple effects, the amount added should be It is preferable to decide in consideration of the action and effect.

The magnetic paint prepared in step 2 is coated on the non-magnetic support described above. At this time, a plurality of magnetic layer paints may be applied sequentially or simultaneously.

Coating can be performed directly onto the non-magnetic support, but it can also be applied onto the non-magnetic support via an intermediate layer such as an adhesive layer.

The intermediate layer herein refers to a layer of adhesive alone or a composite SN formed by dispersing non-magnetic fine particles such as carbon black in a binder.

The intermediate layer containing the carbon blank can be arbitrarily selected from among various binders that can be used in magnetic layers as a binder. The particle size of carbon black is preferably 10 to b, and the weight ratio of binder m to carbon black is preferably 100:10 to 100:150. The thickness of the intermediate layer is 0.1 to 2 μm if it is just an adhesive layer.
In the case of a composite layer containing nonmagnetic powder, the thickness is preferably 0.5 to 4 μm.

In addition, a lubricant that is the same as or different from that used in the magnetic layer may be added to the intermediate layer.

Details of the method of dispersing the above-mentioned ferromagnetic powder and binder and the method of coating it on a support are described in Japanese Patent Laid-Open Publications No. 54-46011 and No. 54-21805.

The thickness of the magnetic layer applied in this way is generally in the range of about 0.5 to 10 μm, usually 0.7 μm after drying.
It is applied so that the thickness is in the range of ~6.0 μm.

When a magnetic recording medium is used in the form of a tape, the magnetic layer coated on the non-magnetic support is usually subjected to a treatment for orienting the ferromagnetic powder in the magnetic layer, that is, a magnetic field orientation treatment, and then dried. On the other hand, in the case of a disk-shaped medium, non-orientation treatment is performed using a magnetic field in order to eliminate anisotropy in magnetic properties. Thereafter, the surface is smoothed if necessary, and then cured by heat curing and/or radiation irradiation if necessary, and then cut into a desired shape.

On the side of the non-magnetic support on which the magnetic layer is not provided,
A known hacking layer may be provided.

An example of manufacturing the ferromagnetic metal thin film magnetic recording medium of the present invention will be described.

Materials for the ferromagnetic metal thin film include iron, cobalt, nickel and other ferromagnetic metals, Fe-Co, Fe-Ni,
Co-Ni, Fe-Rh, Co-P, Co-B, Co-
Y, Co-La, Co-Ce.

Co-Pt, Co-3m, Co-Mn, Co-Cr, F
e-Co-Ni, Co-N1-P, Co-N1-B, C
o-Ni-Ag, Co-Ni-Nd5Co-Ni-Ce
, Co-Ni-Zn, Co-Ni-Cu, Co-Ni
-W.

A ferromagnetic alloy such as Co-Ni-Re is formed by methods such as electroplating, electroless plating, vapor phase plating, sputtering, vapor deposition, and ion blating, and the film thickness is determined when used as a magnetic recording medium. 0.02~2μ
m, particularly preferably a range of 0.05 to 0.4 μm.

Electromagnetic conversion characteristics and durability can be improved by introducing oxygen into the various ferromagnetic metal thin films described above, for example, by vapor deposition in an oxygen stream when forming the metal thin film. In addition to oxygen, N, Cr, Ga, As,
Sr, Zr, Nb, Mo, Rh,, Pd, Sn, Sb,
Te, Pm, Re, Os, Ir, Au, Hg, Pb, B
It may include i etc.

The surface shape of the above magnetic layer is not particularly defined, but 1 to 5
00nm (nm: nanometer - 10-” meter)
Especially when it has protrusions with a height of , it has excellent running performance and durability.

When the compound of the present invention is top coated on the metal thin film, the surface of the metal thin film can be modified with a surfactant such as a fatty acid or various cambling agents before providing the top coating layer. Moreover, this top coat layer may be one layer or may consist of a plurality of layers. Note that the above-described modification treatment, top coat layer structure, etc. can also be applied to coated magnetic recording media.

The thickness of the nonmagnetic support is preferably 4 to 50 μm.

Further, an underlayer may be provided on the support in order to improve the adhesion and magnetic properties of the ferromagnetic thin film.

Substrates used in metal thin film magnetic recording media include polyethylene terephthalate, polyimide, polyamide, polyvinyl chloride, cellulose triacetate, polycarbonate,
Plastic bases such as polyethylene naphthalate, polyphenylene sulfide, or AI, Ti, stainless steel, etc. are used.

In order to improve running durability, it is effective to provide minute protrusions on the surface of the support before forming the metal thin film (resulting in providing appropriate irregularities on the surface of the magnetic layer). The density of microprotrusions is 2 x 10' to 2 x 10 B pieces/kaku2, and the height of one protrusion is 1 to 50 nIll (nI
l: nanometers = 10-9 meters) is preferred.

The magnetic recording medium may have any shape such as tape, sheet, card, or disk, but tape and disk shapes are particularly preferred.

[Effects of the Invention] The present invention provides excellent magnetic properties that include the compound of the present invention in the magnetic layer or on the surface of the magnetic layer, so that the reproduction output is high and the coefficient of friction (μ value) does not increase even under low temperature and low humidity, high temperature and high humidity. It is a recording medium. By forming the compound of the present invention into a salt of phosphoric acid ester, which is an anionic compound, with quaternary ammonium, which is a cationic compound, its inorganic property is improved and its affinity with inorganic materials is improved. Therefore, the compound of the present invention exuded from the magnetic layer or on the surface of the magnetic layer is transferred to metal parts such as heads, balls, guides, etc., and has a high affinity with these metal surfaces, and when rubbed, the compound of the present invention is transferred to metal parts such as heads, balls, guides, etc. The compounds of the present invention are neatly aligned and oriented. Further, the compound of the present invention has a high melting point, exhibits a solid lubricating function, and has a high degree of fixation, so it exhibits excellent lubricating performance even in a wide temperature range. In particular, the clay content of the lubricant tends to deteriorate under high temperature conditions, but the compound of the present invention has a high melting point and strong adhesion, so it is thought to exhibit a remarkable improvement effect. Furthermore, when the compound of the present invention is used in combination with a binder containing a polar group, the improvement effect is particularly remarkable. The quaternary ammonium, which is the cationic group of the compound of the present invention, bonds with the cationic group of the polar group of the binder, and the quaternary ammonium, which is the cationic group of the compound of the present invention, bonds with the anionic group of the polar group, and the durability of the lubricant is improved by the so-called anchoring effect to the strong binding agent. It is thought that excellent effects can be achieved because the alignment is improved and there is less disturbance in orientation.

[Example] Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

In addition, the expression "parts" in the examples indicates "parts by weight J."

[Example 1] After cross-dispersing the following composition for 48 hours using a ball mill, 5 parts of polyisocyanate was added thereto, and after cross-dispersing for another hour, 1 part was cross-dispersed using a filter having an average pore size of m. It was filtered and a magnetic paint was prepared. The obtained magnetic paint was applied onto the surface of a polyethylene terephthalate support having a thickness of 10 μm using a reverse roll so that the thickness after drying was 4.0 μm.

Magnetic paint composition/g) 100 parts Lubricant (listed in Table 1) Oleic acid 1 part Butyl stearate 1 part Carbon blank (average particle size 40 nm) 2 parts Methyl ethyl ketone
A non-magnetic support coated with 300 parts of magnetic paint,
Magnetic field orientation was performed using a 3000 gauss magnet while the magnetic paint was still wet, and after drying, supercalendering was performed and slits were made into 8B width samples.
8I of 33! 1 videotape was produced. In addition, sample Nα
Nos. 18 and 23 to 33 are comparative examples, and the rest are examples.

The videotape obtained as described above is v′rR(
Fuji Photo Film ■: 7 using FUJ lX-8)
A MHz signal was recorded and played back. The relative reciprocating output of the videotape was measured when the 7 MHz reproduction output recorded on the reference tape (Comparative Example 23) was set as OdB.

The obtained videotape and a stainless steel pole are brought into contact (wrapping angle 180°) with a tension (TI) of 50 g, and under these conditions, the required amount is obtained to run the videotape at a speed of 3.3 cm/s. Tension (T2) was measured. Based on this measured value, the friction coefficient μ of the videotape was determined using the following calculation formula. (Recorded in Table 1 [) u = 1 / x · I n (Tz/T+) The friction coefficient test was conducted under the conditions of a, 40° C., and 90% RH.

In addition, storage stability was measured by performing the same test after storage at 90° C. for one week. Furthermore, the repeated running durability was measured by running at 50°C150χ and measuring the number of replays until the output became 13 dB or less.

From the results in Table 1, it is clear 'L! ,ur S,
Tomi:, ノ・All the examples used have high playback output,
It can be seen that the friction coefficient is low even under condition a.

[Example 2] A cobalt-nickel magnetic film (thickness: 150 nm) was obliquely deposited on a polyethylene terephthalate film having a thickness of 13 μm to prepare a raw material for a magnetic recording medium. An electron beam evaporation source is used as the evaporation source, and Kobal l--'-y
A Kel alloy (Co: 80 wt%, Ni: 20%) was charged and oblique evaporation was performed in a vacuum FJj 5 X 1O-5 Torr in an oxygen stream at an incident angle of 50 degrees.

Various materials dissolved in methyl ethyl ketone were coated on the original magnetic metal thin film of the obtained magnetic recording medium and dried to prepare samples, designated as Sample Nos. 34 to 56. Furthermore, sample N
o, 34 to 45 are examples, and samples Nα46 to 56 are comparative examples. (See Table 2) The videotape obtained as described above was recorded using a VTR (Fuji Photo Film ■: FUJ IX-8).
A MHz signal was recorded and played back. The relative playback output of the videotape was measured when the playback output of 7Mttz recorded on the reference tape (Comparative Example 46) was set as OdB.

The obtained videotape and a stainless steel pole are brought into contact (wrapping angle 180°) with a tension (T, ) of 50g, and under this condition, the videotape is required to run at a speed of 3.3cm/s. The tension (T2) was measured. Based on this measured value, the friction coefficient μ of the videotape was determined using the following calculation formula. (Listed in Table 2) u-1/π・1. n (Tz/T+) The friction coefficient test was conducted under the following conditions: a, 40°C, 19o% R, H.

In addition, the storage stability was measured by performing the same test after being stored at 90°C for one week.

Furthermore, the repeated running durability was measured by running at 50° C. and 15 oz. and measuring the number of replays until the output became 13 dB or less.

The results are shown in Table 2.

As is clear from the results in Tables 1 and 2, it can be seen that all of the Examples using the compounds of the present invention had high regeneration output, low coefficient of friction, and excellent running durability.

It is also concluded that there is no change in the friction coefficient over time.

On the other hand, when the compound of the present invention is not used and only the tertiary ammonium salt of fatty acid or phosphoric acid ester is used, the regeneration output is also low, and it can be seen that the friction coefficient decreases significantly over time.

Claims (3)

[Claims] (1) In a magnetic recording medium in which a magnetic layer is provided on a non-magnetic support, a fourth phosphoric acid ester represented by the following general formula 1 and/or general formula 2 is provided in the magnetic layer or on the surface of the magnetic layer.
A magnetic recording medium characterized by containing a class ammonium salt. (General formula 1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (General formula 2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, in the formula, R and R^0 are the same or different carbon numbers of 10 or more Represents a hydrocarbon group of 26 or less, m represents an integer of 1 or 2. R^1, R^2, R^3, and R
^4 represents the same or different hydrocarbon group. ) (2) The magnetic layer according to claim 1, wherein the magnetic layer of the magnetic recording medium contains a ferromagnetic powder and a binder, and at least one kind of resin contained in the binder has a polar group. recoding media. (3) The magnetic recording medium according to claim 1, wherein the magnetic layer of the magnetic recording medium is a thin metal film.