JPS5864635A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance the dispersibility of magnetic powder surface-coated with a phosphoric ester having an unsatd. double bond and the durability of a magnetic recording medium, by using the magnetic powder together with a cross- linkable or polymerizable resin binder. CONSTITUTION:Magnetic powder of iron oxide or the like surface-coated with a phosphoric ester having >=1 polymerizable unsatd. double bond such as a reaction product of phosphoric ester having >=2 hydroxyl groups, an acrylic or methacrylic compound having a functional group reactive with an isocyanate group, and a polyisocyanate compound is dispersed in a resin binder consisting of a compound having an isocyanate group produced by reacting vinyl chloride- vinyl acetate with an acrylic or methacrylic compound, a polyol having a polyisocyanate group, and an acrylic or methacrylic compound. The prepared dispersion is applied to a substrate and cross-linked or polymerized by heating or irradiation to obtain a magnetic recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to video tapes, combinatorial tapes, high performance audio tapes, multi-coated tapes, magnetic disks,
This invention relates to improvements in magnetic recording media used as floppy disks and magnetic cards.

In the production of magnetic recording media, magnetic paint is produced by mixing magnetic powder with a resin binder. It is necessary to improve the dispersibility of powders in binders, and various surfactants are used for this purpose.

For example, higher aliphatic alkyl esters, higher fatty acids, phosphoric acid esters of higher alcohols such as phosphoric acid polyoxyethylene alkyl ether, sorbitol higher fatty acid tonoesters,
Attempts have been made to use sodium alkylbenzenesulfonate and betaine nonionic surfactants as dispersants for magnetic powder.

However, the magnetic coating film of magnetic recording media obtained by adding these surfactants to the magnetic coating material has uniform dispersibility of magnetic powder, high filling property, the use of acicular particles, and the oriented cape of round wires. However, on the other hand, it is necessary to increase the relative frictional force during sliding between the coating film surface and the magnetic head, tape running regulation guide pin, rotating cylinder, etc. that constitute the magnetic recording and reproducing system, or to increase the strength of the magnetic coating film. It actually made it worse. Therefore, running stops due to tape sticking to the heads of cassette tapes, video tapes, etc., recorder systems, wah-7-ratters, etc.
Tape running problems such as jitter skew, or
Magnetic coatings often cause problems due to binding of magnetic coating components near the head gap, increased head clogging, increased dropout, and decreased reproduction output.

The above-mentioned problems with the head recorder system become more apparent especially when the head recorder system is used at high temperatures, high humidity, or low temperatures.

The cause of this is that the low molecular weight surfactant that contributes to uniformly dispersing the magnetic powder migrates to the surface of the magnetic coating, or unnecessarily plasticizes the binder of the magnetic coating. be interpreted.

Therefore, as the amount of surfactant increases in order to improve the uniform dispersibility of '-Ca fine particles, the above-mentioned problems become more prevalent.The present invention is based on the addition of these conventional surfactants. This improves the contradictory relationship between improving the dispersibility of magnetic powder and improving the runnability or wear resistance of the magnetic coating film.

That is, the present invention provides a magnetotactic powder modified by coating with a phosphoric acid ester having one or more polymerizable unsaturated double bonds (Table i1), which is used together with a crosslinkable or polymerizable resin binder. As a result, we succeeded in all at once improving the reciprocity of conventionally used surfactants.

That is, the present invention coats the surface of magnetic powder with a phosphoric acid ester having one or more polymerizable unsaturated double bonds, and then coats the base with a magnetic coating material that is kneaded with a crosslinkable or polymerizable resin binder. A magnetic recording medium obtained by coating and crosslinking or polymerizing, preferably as a phosphoric ester having one or more polymerizable unsaturated double bonds, a phosphoric ester of a compound having a divalent or higher hydroxyl group, an incyanate group and This is a magnetic recording medium that uses an acrylic compound having a functional group having the reactivity of 100%, or memecryl, and a polyisocyanate compound.

In the present invention, the crosslinkable or polymerizable resin binder preferably has (4) an isocyanate group obtained by reacting a partially saponified vinyl chloride-vinyl acetate copolymer with a polyincyanate compound. A compound obtained by reacting a compound with an acrylic compound or a methacrylic compound having a functional group that is reactive with an isocyanate group, and ω) a compound having an isocyanate group obtained by reacting a polyol with a polyisocyanate compound; A blend with a compound obtained by reacting an acrylic compound or a methacrylic compound having a functional group that is reactive with the group is used. These (4) are 20~! 5 weight - preferably 50 to 90 weight, and (6) preferably 5 to 90 weight, preferably 10 to
It is recommended to use at a blending ratio of 50% by weight. Crosslinking or polymerization of the resin binder is carried out by heating or by radiation, preferably in an inert gas stream.

Preferred examples of the magnetic powder used in the present invention include, but are not limited to, acicular iron oxide, acicular OCo-coated 11-iron oxide, and Tonshikuke alloy magnetic particles.

Phosphate esters having one or more polymerizable unsaturated double bonds used in the present invention include phosphoric esters of compounds having divalent or higher hydroxyl groups, acrylated metals or methacrylates having functionality that is reactive with isocyanate groups. and polyisocyanate compounds, or phosphoric acid ester capes of hydroxyalkyl acrylates such as Kaya w-p and Kayamer PM2 (manufactured by Nippon Kagyo Co., Ltd.).

However, compared to the latter hydroxyalkyl acrylate, the former can use long-chain alkyl ethers and polyesters as compounds with divalent or higher hydroxyl groups, so the physical properties of the radiation-cured coating film include flexibility and adhesion to the substrate. A magnetic recording medium with excellent electrical properties, magnetic properties, and mechanical properties can be obtained without deteriorating the properties.

Phosphoric esters having one or more polymerizable unsaturated double bonds include phosphoric esters of compounds having divalent or higher hydroxyl groups, acrylic or methacrylic compounds having functional groups that are reactive with incyanate groups, and polyisocyanates. The following is a synthesis example of this OK compound that was reacted with polyhydric alcohol (manufactured by Sanyo Chemical Co., Ltd., PE ()
-400) After dissolving 200 parts in 200 parts of benzene, 4 parts of the reagent phosphorus oxychloride manufactured by Tokyo Kasei was added dropwise while cooling. After stirring at room temperature for about 1 hour, the reaction was allowed to proceed at 80°C for 1 S in a graphene gas flow. After extracting the unreacted phosphorous oxychloride and the equipment generated by the reaction with distilled water, the reactant is fractionated with benzene and water to form a phosphoric acid ester having a hydroxyl group of PEG400 in the form of a pale yellow paste at room temperature, and then polyisocyanate. A 2-hydroxyethyl methacrylate (2-HIMA) adduct of the compound (TDI) is reacted. The thus obtained phosphoric acid ester of a polyhydric alcohol having an unsaturated double bond is curable by radiation.

The polyhydric alcohol used here is PEG40.
0, PEG500, PEG100 (manufactured by Sanyo Chemical Co., Ltd.), PTGIGo%PTG500. P4O 10 ports (manufactured by Nippon Polyurethane Co., Ltd.), alkyl ether P-400
%P-700,? -1000 (Asahi Denka Co., Ltd. $5), SY:CX GUTHYL 410,242E (Above and above, manufactured by Sanyo IHISEI Co., Ltd.), polyether l diol, and polyester polyol. Examples of the isocyanate compound include 2,4-toluene diisocyanate, λ6-toluene diisocyanate, t4-xylene diisocyanate, m-phenylene diisocyanate,
), P-phenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate 1-), Desmodur L, Desmodur L (manufactured by Bayer AG, West Germany), and the like.

Examples of monomers having a group that reacts with an isocyanate group and a curable unsaturated double bond include 2-hydroxyethyl ester, 2-human mixypropyl ester, and 2-hydroxyoctyl ester of acrylic acid or methacrylic acid. Monomers having active hydrogen that reacts with isocyanate groups such as acrylamide, methacrylamide, and N-methyl p-lylacrylamide and containing acrylic double bonds; Also included are monomers containing unsaturated double bonds that have active hydrogen that reacts with isocyanate groups and have curability, such as mono- or diglycerides of long-chain fatty acids that have unsaturated double bonds and alcohol ester compounds.

The phosphoric esters used in the present invention include rounding with polymerizable unsaturated double bonds, polymerization of phosphoric esters by radiation or heat, and cases where a resin binder with polymerizable unsaturated double bonds is used. Polymerization with a resin binder occurs, eliminating the drawbacks of conventional surfactants. When the WM magnetic paint is thermally crosslinked or polymerized, a polymerization initiator or the like may be used if necessary.

As the crosslinkable or polymerizable resin binder used in the present invention, resins having polymerizable unsaturated double bonds, resins having functional groups such as hydroxyl groups, isocyanate groups, etc. are used. Preferably, it is a resin having a polymerizable unsaturated double charge.

By using such a resin, it is possible to have radiation curability.In the present invention, although it does not have polymerizable unsaturated double bonds as described above, it can be cured by radiation irradiation. Resins that can be crosslinked or polymerized can also be used. The use of thermosetting binders has reached its limit in meeting the trend of significantly higher hardness of magnetic recording media and streamlining of production processes. On the other hand, when a radiation-curable resin composition is used, when the magnetic paint is irradiated with electron beam radiation, the unsaturated double bonds in the paint generate radicals due to the radiation, and the radicals cause polymerization. This creates a three-dimensional network structure, causes instantaneous curing at image density, and allows a smooth magnetic coating surface to be obtained with a simple process without shear after-curing. By using a high molecular weight metal material, it is possible to obtain a coating film that is hardenable but has excellent flexibility and good physical properties. As a resin binder having a polymerizable unsaturated double bond, ■ A compound having an incyanate group obtained by reacting a partially anodized vinyl chloride-vinyl acetate copolymer with a polyisocyanate compound is used. By reacting an acrylic compound or a methacrylic compound with a functional group that has reactivity with a polyol, a polyinocyanate compound is reacted with a polyol, and the resulting compound having an isocyanate group has a reactivity with an isocyanate group. A chemical compound made by reacting an acrylic compound or a methacrylic compound with a functional group that has one molecule of a compound containing one or more epoxy groups in the molecule, a group that reacts with the epoxy group, and a curable unsaturated double bond. A reaction product with one or more molecules of monomer ■ A polyester compound containing a curable unsaturated double bond in its molecular chain ■ One molecule of a chemical compound containing one or more carboxyl groups in the molecule and a group that reacts with the carboxyl group and A reaction product with one or more molecules of a monomer having a curable unsaturated double bond is used. Preferably, a compound having an isocyanate group obtained by reacting a polyisocyanate compound with a partially silicified vinyl chloride-acetate vinyl copolymer is acrylated to have a functional group reactive with the isocyanate group. A compound obtained by reacting a metal or a methacrylic compound with a compound having an isocyanate group obtained by reacting a polyisocyanate compound with a trout polyol, and an acrylic compound or a methacrylic compound having a functional group that is reactive with the isocyanate group. The compounding ratio of (4) with the compound formed by the reaction is 20 to t5.
Weight - preferably 50-911% by weight, 5-8 (6)
It is preferably used in amounts ranging from 0% by weight to 10 to 50% by weight.

(2) is a partially saponified vinyl chloride-vinyl acetate copolymer having a hydroxyl group such as vinyl 2ite VAGH (Union Carbide Co., USA) and 2HEMA of TDI.
Examples of (1) include toluene diisocyanate in which 1 mol of binomial polyether (ADEKABORIETHER P-100, Asahi Denka Co., Ltd. 11) is prepared by adding propylene oxide to propylene glycol. 2 moles of 2-hydroxyethyl methacrylate are reacted, and then 2 moles of 2-hydroxyethyl methacrylate are reacted to produce a resin, prebolimer, oligomer, or thea! that has two acrylic double bonds at the end of the molecule. − can be mentioned.

The polyol component used here is Adeca Polyether P-700. ADEKABORIETHER P-1000
, 7 Decaborie f) multifunctional polyethers such as kG-1506 (hereinafter manufactured by Asahi Denka Co., Ltd.), Polymeg 100G, Polymeg 450 (hereinafter Fokker-Cola Company 11); Polycabrilactone PCP-0200, Polykab 4 ctyPCP-0240゜Polycabu-Lactone PCP-〇5
00 (hereinafter manufactured by Chisso Corporation) polyfunctional polyesters;
7 Talic acid, isophthalic acid, terephthalic acid, adipic acid,
Saturated polybasic acids such as succinic acid and cepatic acid and ethylene glycol, diethylene glycol, 14-butanediol, Is-butanediol, $2-propylene glycol, dibutetrapyrene glycol, L6-Henakasan glycol, neopeyf Saturated polyester resin obtained by ester bonding with polyhydric alcohols such as lucricol, glycerin, trimethytetrabutane, and pentaerythritol; acrylic polymer containing at least one hydroxyl group-containing acrylic ester and methacrylic ester as a polymerization component can be mentioned.

9. The polyisocyanate compounds used include L4-) toluene diisocyanate, 2.4-) toluene diisocyanate, t4-xylene diisocyanate, m-phenylene diisocyanate*-), P-phenylene diisocyanate, hexamethylene diisocyanate. ,
There are isophorone diisocyanate Yatesmodur L and Desmodur IL (manufactured by Bayer AG, West Germany) Cape.

Monomers having a group that reacts with an isocyanate group and a radiation-curable unsaturated double bond include 2-hydroxyethyl ester of acrylic acid or methacrylic acid, 2-hydroxyethyl ester of acrylic acid or methacrylic acid;
Hydroxypropyl ester, 2-hydroxyoctyl ester MisakiEsters having a hydroxyl group; acrylmite, methacrylamide, N-methylol acrylamide A monomer containing an acrylic double bond and an active hydrogen that reacts with the isocyanate group. In addition, 1 acrylic alcohol, maleic acid polyhydric alcohol ester compound, unsaturated double compound having active hydrogen that reacts with the mono- or diglyceside isocyanate group of long-chain fatty acids having unsaturated double bonds and having radiation curability. Monomers containing linkages are also included.

In the resin binder of the present invention, when a compound having a radiation-curable unsaturated double bond is mixed with O, the blending ratio (by weight) of (4) and (to) is 20~! 5. Good investment strategy 5
0~! 0, (6) is 5-80. If it is preferably 10 to 50, Vinylite VAGH, which is a partially saponified and circularly cyclized vinyl-vinyl acetate copolymer, has flexibility by itself, but has radiation ls curability and hardness to the substrate base. Adhesive properties are quite poor.

Furthermore, there are other problems such as the increase in the viscosity of the magnetic paint. Therefore, as component (6), a low molecular weight compound with excellent O compatibility with component (2) is used to increase the crosslinking density, improve radiation curability, and form a base material base and 0111! A surface compound is blended to impart adhesion. In addition, the use of low molecular weight compounds lowers the viscosity of the magnetic paint and improves the paintability, and the use of high molecular weight compounds improves the dispersibility of magnetic powder 4b! On the other hand, in the case of a compound in which excellent flexibility cannot be obtained as (4), a combination with component (4), which imparts radiation curability and adhesion to the substrate as (B), Compounds with good compatibility can be blended, and if the resin has plasticity, flexibility can be imparted to the cured coating film.

(6) also improves the dispersibility of the magnetic powder, but in order to shorten the dispersion process, the use of a phosphoric acid ester having one or more polymerizable unsaturated double bonds according to the present invention improves the dispersibility. Furthermore, it is possible to further improve the dispersion process, shorten the dispersion process, and further improve the electrical, magnetic, and mechanical properties of the magnetic recording medium.

A soft resin in which a crosslinkable or polymerizable resin binder has a polymerizable unsaturated double bond such as an acrylic double bond, a maleic double bond, an allyl double bond, and the double bond described above. or its prepolymer, oligomer, tessemer (dynamic elastic modulus at 20°C lX10'
dyn/e) is also a preferred embodiment.

Although a solvent is used in the present invention, the magnetic particles/binder (weight-ratio) is 85/1S to 6 in consideration of the magnetic properties and adhesive properties of the coating film formed on the substrate base film.
s/! When adjusting to the Is O range, the solid content of the magnetic paint using a solvent is 20 to 40 weight - 1, preferably 25 to 4
By adjusting the weight within the range of 0 to 110, it is possible to obtain a magnetic paint with good coating suitability.

There is no particular limit to the solvent, but it is appropriately selected in consideration of the solubility and compatibility of Pine Goo O.

For example, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone@0 ketones, ethyl formate, ethyl acetate, butyl acetate esters, methanol, ethanol, allyls such as isop-4-(nol, phthanol), toluene. , xylene, ethylbenzene@
Aromatic hydrocarbons, isobuyl ether, ethyl ether, dioxane cape ethers, tetrahedron W7, furfural and other furans are used as a single solvent or as a mixed solvent thereof.

The substrate to which the magnetic paint according to the present invention is applied is polyethylene terephthalate film, which is currently widely used as a base material for magnetic recording media, and polyimide film, polyamide film, etc. are used for applications that require further heat resistance. be done.

In particular, in the case of Nipolyester films, there are many cases in which thin films are subjected to uniaxial stretching and biaxial Shinigami treatment. It is also used to coat paper.

The magnetic fine powder coated in the present invention is r -P@
,O,,Fe,04,Co-doped γ-Fe,Os.

C6 doped 7- Fe, O, -F'S, 04 solid solution, C
o-based compound-coated γ-Fe, 0. , Co-based compound-coated p'@s04 (γ-Fe, also includes an intermediate oxidation state with 0.

The CO-based compound referred to here refers to cobalt oxide, cobalt hydroxide, cobalt ferrite, cobalt ion adsorbate, etc., in which the magnetic anisotropy of cobalt is utilized to improve coercive force. Co, Fe-Co.

A wet reduction method using a reducing agent such as BH4, which mainly consists of a ferromagnetic metal such as F・-CO-Ni, Co-N1, or a dry reduction method using a ridge, H, or Game force where the surface of iron oxide is treated with a St compound. These are fine metal particles and single crystal barium ferrite fine powder obtained by various manufacturing methods, such as by vacuum evaporation in a low-pressure argon gas stream. The above-mentioned magnetic fine particles are used in the form of needles or particles, and are selected depending on the intended use as a magnetic recording medium.

High-bias H1Fi audio cassette tapes have seen remarkable technological advances in recent years, and their marketability is likely to expand.
Videocassette tape, videotape contact transfer print F
In the master tape cape for use in the present invention, among the binder of the present invention and the above-mentioned magnetic fine powder, Pbalt-modified acicular iron oxide (cobalt-doped type or cobalt-based compound coated type), which is particularly advantageous for high-density recording applications, or even higher-temperature By combining magnetic acicular alloy fine particles with silk, we were able to obtain a high-performance tape with extremely good electromagnetic f exchange characteristics and intellectual reliability.

Regarding the magnetic paint of the present invention, various antistatic agents, lubricants, dispersant sensitizers, leveling agents, abrasion resistance imparting agents, coating film strength reinforcing additives, etc., which are commonly used depending on the purpose, are used as appropriate depending on the purpose. Then it is beneficial.

The present invention (the related phosphoric acid ester is applied to the magnetic powder [L5~
10% by weight of aromatic hydrocarbons from Toluene,
Magnetic powder is developed by stirring thoroughly in a solvent such as acetone, methyl ethyl ketone, cyclohexanone, etc., alcohols such as isopropyl alcohol, butanol, esters such as ethyl acetate, butyl acetate, water, etc. Then, it is coated by heating and drying.

The coated magnetic powder is kneaded with a crosslinkable or polymerizable resin binder in a disperser to obtain a magnetic paint.

After that, it is applied to a base film (polyester, etc.), dried, and subjected to surface treatment. Radicals generated from the polymerizable unsaturated double bonds of the phosphoric acid ester are exposed to the binder or Forms a polymerization or crosslinking reaction with phosphoric acid esters to increase the molecular weight,
By incorporating it as a part of the binder component, it contributes to the uniform dispersion of the phosphate ester L magnetic powder, prevents it from migrating to the surface of the magnetic coating film, which has an adverse effect on the reliability of the tape's physical properties, and acts as a dispersant. It is characterized by playing an ideal role.

In the system using the dispersant according to the present invention, it is preferable to use a resin binder having two or more unsaturated double bonds that is curable by radiation as the binder to be mixed.

However, compared to conventionally commonly used binders mainly composed of thermoplastic resins and thermosetting binders made by reacting isocyanate compounds using O water groups in the resin, the coated magnetic powder of the present invention can be used.

The radiation used for crosslinking and curing the magnetic coating film according to the present invention includes electron beams using an electron beam accelerator as a radiation source, T-rays using COo as a source, nine β-rays using Sr0 as a source, and X-rays. A ray generator is used as a ray source and 9X# beams are used. In particular, as an irradiation source, it is advantageous to use an electron beam from an electron beam accelerator from the viewpoint of controlling the absorbed dose, introducing it into the manufacturing process line, blocking ionizing radiation O, etc.

The characteristics of the electron beam used when curing magnetic coatings are as follows:
From the viewpoint of penetrating power, it is convenient to use an electron beam accelerator with an accelerating voltage of 100 to 750 KV, preferably 150 to 500 KV, and irradiate at an absorbed dose of a5 to 20 megaland.

In particular, in the case of magnetic tape, the thickness of the coating to be cured is small, so a low-dose type electron beam accelerator (electrocurtain system) manufactured by Energy Sciences, Inc. in the United States is used to process the tape coating. This is extremely advantageous for blocking 02-order X-rays.

Of course, a van de Graaf type accelerator, which has been widely used as a stain beam accelerator, may also be used.

First, during radiation curing, it is important to irradiate the magnetic coating film with radiation in an inert gas stream such as N, gas, or He gas. Since the film is extremely porous, irradiating it with electron beams in the air will cause the 9 radicals generated in the polymer to become effective due to the effects of 02 etc. produced by radiation irradiation during crosslinking of the binder component. Inhibits cross-linking reaction. Since the surface of the magnetic layer is naturally porous, the inside of the coating film is also affected by the binder's crosslinking inhibition. Therefore, it is important to maintain the atmosphere of the part to be irradiated with an inert gas such as N, H., CO, or #.

Next, the present invention will be specifically explained using Examples and Comparative Examples. In addition, "parts" in the examples indicate parts by weight.

Prior to the examples, a synthesis example of a phosphoric acid ester and a resin binder used for coating magnetic powder will be described.

Dispersant synthesis example (&) 420 parts of PTGloG (manufactured by Nippon Polyurethane Co., Ltd.) was dissolved in 42 to 42 parts of benzene (IK), and phosphorus oxychloride (1 g) was dissolved in 42 parts of benzene (IK).

4 parts of Kyoto Kasei reagent grade 1) a were gradually added dropwise while cooling, and after stirring at room temperature for about 1 hour, the temperature was raised to 80° C. and the mixture was reacted with stirring for 15 hours. Extract unreacted phosphorus oxychloride and generated hydrochloric acid from the reaction product in the benzene solution with distilled water,
Then, benzene and water were finally fractionated under reduced pressure to obtain a pale yellow phosphoric acid ester in the form of base F at room temperature. After heating and melting 120 parts of phosphoric acid ester containing 10 parts of PTG, 5 parts of TDI adducts, 0 parts, 1001 parts of tin cutylate, and hydrquinone (LOOI part) were added and reacted at 80° C. for 2 hours.

Dispersant synthesis example (b) Polycarbonate PCP-0240 (Chisso Corporation g) I
Part ooo, 1000 parts of benzene, and 114 parts of phosphorus oxychloride were reacted in the same manner as in dispersant synthesis example (a) to obtain PCP-0240.
304 parts of the phosphoric ester, 'rD
12 parts of I adduct, 002 parts of tin octylate, and 02 parts of hehydroquinone (L@02) were reacted in the same manner as in the dispersant synthesis example (IL).

200 parts of PP0400 (manufactured by Nippon Ichidasha) was added to benzene sO.
Dissolved in O part, oxydiphosphorus (Tokyo Kasei Reagent Grade 1) &4
The mixture was gradually added dropwise without cooling, and after stirring at room temperature for about 1 hour, the temperature was raised to 80°C and the mixture was stirred and reacted for 11 seconds. Unreacted phosphorus oxychloride and generated hydrochloric acid are extracted from the reaction product in the benzene solution with distilled water, and the benzene and water are finally fractionated under reduced pressure to obtain a pale yellow paste-like phosphoric acid ester at room temperature. Phosphate ester of @PPG400 120
120 parts of TDI adduct, 1 part of tin octylate (LQO, 1 part of hydroquinone IIL00) were added and reacted at 80°C for 2 hours.

Dispersant synthesis example (d) 200 parts of Nupol PE-400 (manufactured by Sanyo Kasei Co., Ltd.) was dissolved in 500Hc of benzene, 4 parts of phosphorus oxychloride (Tokyo Kasei reagent grade 1) was cooled, and the mixture was gradually added dropwise to the solution at room temperature. After stirring for about 1 hour, the mixture was heated to SO 0 C and reacted with stirring for 11 parts. Unreacted phosphorous oxychloride and generated hydrochloric acid are extracted from the reaction product in the benzene solution with distilled water, and benzene and water are finally fractionated under reduced pressure to obtain a pale yellow base Y-shaped O-phosphoric acid at room temperature. After heating and melting 120 parts of phosphoric acid ester of 9mPK-4@fJ to obtain ester, TDI adduct body 12
．． 0 parts of tin octylate, 1001 parts of tin octylate, and aoot parts of hyde tetraquinone were added and reacted at 80°C for 2 hours.

Synthesis of TDI adduct Tolylene diisocyanate (TDI) I 41 parts tN, after heating to 80°C in a 1 ton airflow flask, 26 parts of 2-hydroxyethyl methacrylate (lHEM), 07 parts of tin octylate α , the hydride p-quinone aOS part was cooled to a temperature of 80 to 85°C in the reaction vessel.
-J/, and after the completion of the dropwise addition, the reaction was completed by stirring at 80°C for 5 hours. After the reaction was completed, the reactor was taken out and cooled, to obtain TDI 2HEMA Adak F in the form of a white paste.

Next, an example of binder synthesis will be shown.

17 parts of vinyl chloride/vinyl alcohol combined Note 1, 1250 parts of toluene, and 4 parts of sicum hexanoysea were placed in a 3-ton flask, heated and dissolved, and after raising the temperature to 80°C, 2-hydroxyethyl methacrylate adatate of tolylene diisocyanate was prepared. Added 414 parts of tin octylate, added 1012 parts of tin octylate, added 1012 parts of hydroquinone
“C and N.

Let the reaction occur until the NCO reaction rate in the air stream reaches 9091 or higher.

After the reaction is completed, cool and methyl ethyl ketone 12! Part I@ was added and diluted.

The resulting composite is referred to as binder (a).

iQ Vinyl chloride and alcohol 114rp.

The production (vinyl chloride group/vinyl acetate group) ratio is 75/25,
Average degree of polymerization Hsw Vinyl chloride-vinyl acetate copolymer is used as a raw material, and this is MIBK (methyl isobutyl ketone) @
The resin was suspended in a mixed dispersion medium of a solvent and water, and mechanically dispersed using a stirrer to create a suspension similar to a slurry of swollen resin.

Next, monocarboxylic sodium methizoate was added as a catalyst, and the temperature was maintained at around 80°C to saponify the acetyl group of vinyl acetate to a hydroxyl group.

In addition, it may be better to use a stabilizer to prevent dehydrochlorination or a suspending agent to ensure uniform suspension.

Next, the acetic acid and catalyst that are eliminated and generated from the acetyl group are
The saponified slurry was removed (by washing with water) to improve resin O stability. In this case, if necessary, a rounding step to remove coloring during saponification, a decoloring step to remove chlorine ions, etc. may be added.

The vinyl chloride-vinyl alcohol copolymer obtained by the saponification method 1 described above had the following properties.

Vinyl chloride group 87 Vinyl thiacetate group Aid or less Vinyl alcohol group 12.6 thi Polymerization degree 55G Polyether PTG-500ff manufactured by Nippon Polyurethane Co., Ltd.
iNo Club, 2HEMA! 15 parts, Hytroquinone 10
07 parts, tin octylate a00! Place 8 parts into a reaction can.
After heating and dissolving at 0°C, 418 parts of TDI was added dropwise while cooling so that the temperature inside the reaction vessel was 80-9Q'C, and after the dropwise addition was completed, the reaction was allowed to occur at 80°C until the NC0 reaction rate reached 95- or higher. . The resulting nine composites were designated as binder (b).

Hereinafter, the first invention will be explained based on the following examples.

Example-1 Acicular magnetic iron oxide 'r-F・, O, (long axis 1 bμ, short axis 1
04μ, He11000.) 120 parts Phosphoric ester (substance from phosphoric ester synthesis example (a)) 4 parts Agent I (methyl ethyl ketone/toluene 50150) 10
These magnetic powders and each component were simultaneously or sequentially put into a mixer or mixer, and stirred and mixed for a period of time to form several layers of phosphoric acid ester on the surface of the magnetic powder. As the stirring mixer, various devices such as a ball mill, a roll mill, a high speed impeller disperser, a sound ground mill, a homogenizer and an ultrasonic synthesizer can be used.

Next, spread out the magnetic powder that has been stirred and mixed for 1 minute, for example, 20 minutes.
The magnetic powder was dried by heating at a temperature of ~120° C. for about 50 minutes to 150 hours, thus coating the surface of the magnetic powder. The thus coated magnetic powder was used below.

Acicular coated magnetic iron oxide γ-Fe, 0. 120 parts by weight were mixed in a high-speed mixer for 1 hour, and the resulting slurry was dispersed in a sound ground mill for 4 hours.

The obtained paint was applied onto a 12μ polyester film, oriented on a permanent magnet (1400 gauss), the solvent was dried (with hot air in front of an infrared lamp), the surface was smoothed after death, and an electrocurtain manufactured by ESI was applied. Using a type electron beam accelerator, the acceleration voltage was 150 K e V%.
Electron beams were irradiated under conditions of an electrode current of 1120 mA and a total irradiation dose of 5 Mrad in a nitrogen atmosphere, thereby making the sample electrosensitive and reacting with the required dispersant. Although the structure of the dispersant after the reaction in this case is not clear, it is thought that the dispersant is polymerized by radical polymerization of itself or the dispersant and binder are bonded by a radical reaction.

The obtained tape was cut into 58-width pieces to obtain an audio cassette tape (Sample 1).

Example 2 An incyanate compound (Bayer Co., Ltd. 11m des module) capable of crosslinking with functional groups mainly containing hydroxyl groups in binder O was added to the magnetic paint obtained by dispersing Schisand Grind ζ in Example 1. 5 parts of L") were added in terms of solid mass, and after thoroughly mixing with an electric mixer, it was immediately placed on a 12μ polyester film, subjected to magnetic field orientation treatment, drying, surface smoothing treatment, and a heat treatment oven maintained at 60°C. It was held for 4 hours.

Thereafter, electron beam irradiation was performed under the same conditions as in Example 1, and the tape was cut into 58 mm width pieces to obtain an audio cassette tape (sample φ2).

In Examples 1 and 2, 1 polymerizable unsaturated double bond
A cassette tape manufactured using a magnetic powder coated with a phosphoric acid ester having at least 10% of phosphoric acid esters is compared with the tapes obtained in Comparative Examples 1 and B below.

Comparative Example A Dispersant (substance from Dispersant Synthesis Example ■) 4 parts Solvent (Methyl Ethyl Ketone/Toluene" 15. > 1 01
The above composition is mixed in a high-speed mixer for S hours to thoroughly wet the acicular magnetic iron oxide with the dispersant.

Vinyl chloride-vinyl acetate (Vinyrite MIH manufactured by Union Carbide) 1
5°C Solvent (methyl ethyl ketone) 20 parts Lubricant (stearic acid) Nose This was mixed with the previously treated magnetic powder in a high-speed mixer for 1 hour, and the resulting slurry was passed through a Nara/Dog Grand Mill. Dispersion was carried out for 4 hours using a circle.

The resulting paint was used to produce a cassette tape using the same manufacturing method as in Example 1.

In Comparative Example B as well, magnetic powder was used without any ambiguity, and a cassette tape was obtained using the tk# manufacturing method as in Example 2.

Table IK below shows the measurement results for the audio cassette tapes of Examples 1 and 2 and Comparative Examples A and B.

Table 1 Characteristics of Audio Cassette Tape As can be seen from Table 1, in the case of using coated magnetic powder, the coating strength was strong and the head adhesion resistance was low. In addition, since the magnetic properties are excellent in orientation and the surface properties are good, the electromagnetic conversion characteristics are improved at RF4MHz, and the result is also excellent in 8/N.

Example-S Cobalt-coated acicular γ-F@, O, (long axis 14 tones, short axis a
Gs, a, He4G00s) 126 parts) phosphoric acid ester (substance from dispersant combination example rb)) 7 parts Solvent (methyl ethyl ketone/toluene 50150) 1
600 parts In the same manner as in Example 1, these compositions were mixed and dried by heating to coat the surface of the magnetic powder.

Using the coated magnetic powder, and carbon black (for antistatic use, Mitsubishi Carbon Black MA-doO)' 5 parts r
-Al, O, powder (15μ granules) 2 parts Solvent (methyl ethyl ketone/toluene so/5o) 1 t
10 parts and mixed in a ball mill for S hours. Resin (binder (a)) 15 parts (solid content equivalent) Resin (binder (b)) 1 part (solid content equivalent) Solvent (methyl ethyl ketone/toluene s a7so) 200
Part: Lubricant (higher fatty acid-free silicone oil) Part: S: The above binder mixture was placed in the ball mill that had been subjected to the magnetic powder treatment and mixed and dispersed again for 42 hours.

The magnetic paint thus obtained was applied onto a 15 μm polyester film, subjected to magnetic field orientation treatment, solvent drying, surface smoothing treatment 1, and accelerated voltage using an ELECT four-curtain type electron beam accelerated snow coating manufactured by ESI. Irradiate with electron beam under N3 atmosphere under conditions of 1soK@V% electrode current 20 mA, total irradiation dose IQ Mrad t), and thus cure the coating film.

Cut the resulting nine tapes into 2-inch-wide pieces to obtain a videotape (sample φi).

The crosslinking of the magnetic coating O by this method is thought to be due to both the crosslinking due to the radicalization of the ataryl double bond and the crosslinking due to the radicals generated in the vinyl acetate molecular chain (possibly due to Hcl removal, but it is not clear). It will be done.

Comparative Example C This example was the same as Example 3 except for the point plate in which the surface of the magnetic powder was not coated.

Figure 1 shows the edge of the videotape on which signals are distributed using an FIAJ unified standard oven reel VTR (NY-5120 made by Matsushita Electric Industrial Co., Ltd.). Indicates the amount of attenuation (still regeneration) for the regeneration output at the time of death.

As is clear from the figure, despite severe abrasion conditions in which the relative speed between the magnetic coating film and the head was as high as 11 m/se6%'c, sample φ was cross-linked with the phosphoric acid ester resin binder by radiation. By doing so, the dispersant, which has a strong characteristic of increasing the coefficient of friction at high speeds and promoting the destruction of the magnetic coating, is bound by the magnetism coated, so it is less likely to stand out on the surface, and the coating is also strong. Signal attenuation is significantly less,
However, as shown in Table 2, the results of actual running at 4.40 DEG C. and 60 DEG C. show that the coating strength is strongly the same.

Table 2 It is also believed that the low dropout after running is closely related to the strength of the magnetic coating, as shown by the steel properties and head adhesion during high-temperature running.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram of the present invention and a comparative example. Figure 1 Continued from page 1 0 Inventor Yu Kubota - Tokyo Denki Kagaku Kogyo Co., Ltd. 1-13-1 Nihonbashi, Chuo-ku, Tokyo 0 Inventor Kazushi Tanaka 13-1 Nihonbashi-1, Chuo-ku, Tokyo Inventor within Tokyo Denki Kagaku Kogyo Co., Ltd. Osamu Shinoura 13-1 Nihonbashi-chome, Chuo-ku, Tokyo Tokyo Denki Kagaku Kogyo Co., Ltd. Inventor Yukihiro Isobe 13-1 Nihonbashi-chome, Chuo-ku, Tokyo Tokyo Inside Denki Kagaku Kogyo Co., Ltd. @Applicant: Tokyo Denki Kagaku Kogyo Co., Ltd., 1-13-1 Nihonbashi, Chuo-ku, Tokyo Procedural Amendment December 1, 1978 Commissioner of the Japan Patent Office Shima 1) Indication of Haruki Tono case Showa 1956 Japanese Patent Application No. 142800 Title of the invention Relationship to the case of persons who correct magnetic recording media Name of patent applicant Pestle
Toyo Ink Mfg. Co., Ltd. (one other person) Subject of agent's amendment Contents of amendment in the detailed explanation column of Akira Deposit As shown in the attached document, the previously submitted specification is amended as follows. t "Kayamar P" in lines 2 to 5 on page 8 is corrected to [Kayamar PMIJ. 2. Delete "Modified Essushimer" in lines 5-4 from No. 50. In the first line from the bottom of page 31, "Sounderand" is corrected to "Soundgrind."

Claims (9)

[Claims] (1) Coat the surface of magnetic powder with a phosphoric acid ester having one or more polymerizable unsaturated double bonds, and knead it with a crosslinkable or polymerizable resin binder to create a magnetic paint.
A patented magnetic recording medium that is coated onto a substrate and then crosslinked or polymerized. (2) Acrylic or methacrylic compounds in which the phosphoric acid ester having one or more polymerizable unsaturated double bonds has a functional group that is reactive with the phosphoric acid ester of a compound having a divalent or higher glacial acid group, or an isocyanate group. , and a polyisocyanate compound. 2. The magnetic recording medium according to claim 1, which is obtained by reacting a polyisocyanate compound with a polyisocyanate compound. (3) Claim f where the phosphoric acid ester is a phosphoric acid ester of hydroxyalkyl acrylate! [Magnetic recording medium according to item 1. (4) The amount of phosphoric acid ester used is 15 to 1 per magnetic powder.
7. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is within the range of 0 weight. (5) A crosslinkable or polymerizable resin binder is added to a compound having an incyanate group obtained by reacting a polyisocyanate compound to a partially saponified vinyl nonachloride-vinyl acetate copolymer. A compound obtained by reacting a functional group with an acrylic compound or a methacrylic compound, and a compound having an isocyanate group obtained by reacting a polyol with an isocyanate compound has reactivity with an isocyanate group. The magnetic recording medium according to claim 1, which is a mixture with a compound obtained by reacting an acrylic compound or a methacrylic compound having a functional group. (6) The blending ratio in the compound is (4) Compound 2G
The magnetic recording medium according to claim 5g4, wherein the amount of the compound 5 to 5a1i is 1 to 95% by weight. (7) The magnetic recording medium according to any one of claims 1 to 4, wherein the magnetic powder is acicular iron oxide, acicular cobalt-coated iron oxide, and/or an alloy magnetic material. (8) The magnetic recording medium according to any one of claims 1 to 7, wherein the crosslinking or polymerization is carried out by heating or irradiation with radiation. (9) The magnetic recording medium according to claim 8, wherein the crosslinking polymerization by heating or radiation irradiation is carried out in an inert gas stream.