JPS6363128A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the dispersibility of magnetic powder, the surface characteristic of a magnetic layer and the durability, magnetic characteristics, etc. of a titled medium by incorporating a phenoxy resin contg. electron rays sensitive double bonds in the molecule and sulfonic acid group or metal base of sulfonic acid as a binder into the magnetic layer. CONSTITUTION:The magnetic layer essentially consisting of the ferromagnetic powder and binder is formed on a nonmagnetic base. The magnetic layer contains the phenoxy resin contg. the electron rays sensitive double bonds in the molecule and sulfonic acid group or metal base of sulfonic acid as the binder. The phenoxy resin has high coated film strength and is produced from; for example, bisphenol A and epichlorohydrin. Such resin exhibits high affinity to the magnetic powder and has good dispersibility even with the ultrafinely pulverized magnetic powder or the magnetic powder having a large quantity of magnetization. The durability and surface characteristic of the resulted magnetic recording medium are, therefore, improved and the recording medium having the extremely good electromagnetic conversion characteristic is obtd.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic recording medium such as a magnetic tape, and more particularly to a binder contained in a magnetic layer formed on a non-magnetic support. This is related to the improvement of.

[Summary of the invention]

The present invention provides a magnetic recording medium in which a magnetic layer mainly composed of ferromagnetic powder and a binder is formed on a non-magnetic support, wherein the magnetic layer has an electron beam sensitive double bond and a sulfonic acid group in the molecule. Or, by containing a phenoxy resin containing a sulfonic acid metal base as a binder, it is possible to improve the solid content of the paint, improve the pot life, simplify the manufacturing process, and improve the dispersibility of the magnetic powder and the strength of the magnetic layer. The durability of the magnetic recording media obtained by improving the surface properties,
The aim is to improve magnetic properties, electromagnetic conversion properties, etc.

[Conventional technology]

In recent years, magnetic recording media, especially magnetic recording media for VTRs (video tape recorders), have been required to have improved magnetic properties and electromagnetic conversion properties in order to obtain high playback output even when recording at short wavelengths. There is.

As a way to achieve this goal, we developed finer particles of magnetic powder.

As the magnetic force is increased, there is a strong tendency to increase the packing density of magnetic powder in the magnetic layer, the so-called backing density.

On the other hand, conventionally used binders for magnetic recording media include vinyl chloride-vinyl acetate copolymer, vinyl chloride-propionic acid copolymer, and vinyl chloride-vinyl acetate copolymer.
Examples include vinyl chloride-based binders such as vinyl alcohol copolymers, among which the hydroxyl groups of vinyl alcohol contribute to the dispersibility of the magnetic powder, and the active hydrogen of the hydroxyl groups reacts with isocyanate compounds to form a crosslinked structure. Vinyl chloride-vinyl acetate-vinyl alcohol copolymer is widely used because it increases the mechanical strength of the coating film formed.

However, with the above-mentioned demands for increased backing density and improved durability, various problems have arisen with these vinyl chloride-based binders.
The current situation is that it is difficult to take adequate measures.

For example, as the specific surface area increases due to finer particles of magnetic powder and the cohesive force increases due to high magnetizing force, it is not possible to obtain a satisfactory dispersion system and surface area with the above-mentioned main binder, and the backing density of magnetic powder increases. It is also difficult to increase the amount. Therefore, durability, magnetic properties,
The electromagnetic conversion characteristics were also insufficient. In particular, performance has been insufficient for ultrafine magnetic powders that are compatible with high recording densities and magnetic powders that have a high amount of magnetization. In this case, for example, a method such as using a surfactant as a dispersant may be considered, but since the surfactant is a low molecular weight, powder dropout and pluming due to changes over time may occur, resulting in poor mechanical strength and durability. There are problems with this.

In addition, the dispersibility of the above-mentioned magnetic powder is improved.

In addition to improving the physical properties of the coating film to improve durability, there is also a need to simplify the process from a manufacturing standpoint. Generally, in order to cure the above-mentioned binder after application, the method of applying heat or adding a curing agent to accelerate polymerization is adopted, but there are limitations in terms of cohesiveness of paint solids and pot life. There are many
Workability is worsened.

[Problem that the invention seeks to solve]

There are many issues that need to be resolved in terms of film properties, handling during manufacturing, etc., and it has been difficult to ensure desired durability, magnetic properties, and electromagnetic conversion properties.

Therefore, the present invention was proposed in order to eliminate the above-mentioned drawbacks in the technical field, and is aimed at improving the dispersibility of magnetic powder, the f# quality of the chamber in the coating film when formed as a magnetic layer, and improving the f# quality of the coating film when formed as a magnetic layer. The purpose of the present invention is to provide a binder having excellent properties in terms of workability, etc., and to provide a magnetic recording medium with excellent surface properties and durability, and good magnetic properties and electromagnetic conversion properties.

[Means for solving problems]

The present inventors have discovered that by introducing a sulfonic acid group or a sulfonic acid metal base into the side chain as a polar group, high affinity is exhibited for magnetic powder, and that the introduction of an electron-sensitive double bond improves workability. The present invention was completed by paying attention to the fact that it is effective in improving the magnetic field of magnetic fields, and the present invention is formed by forming a magnetic layer mainly composed of ferromagnetic powder and a binder on a non-magnetic support. The magnetic recording medium is characterized in that the magnetic layer contains, as a binder, a phenoxy resin containing an electron beam sensitive double bond and a sulfonic acid group or a sulfonic acid metal base in the molecule.

The phenoxy resin used in the present invention has excellent coating strength and is produced from, for example, bisphenol A and epichlorohydrin.

Its basic structure is shown by the following structural formula (1).

(However, in the formula, n represents an integer of 20 to 200.) In order to introduce a sulfonic acid group or a sulfonic acid metal base as a hydrophilic polar group into the above-mentioned phenoxy resin, the hydroxyl group of the side chain of the above-mentioned phenoxy resin is used. The compound may be modified with a compound having a group capable of reacting with active hydrogen and a sulfonic acid group or a sulfonic acid metal base in the molecule.

A, l A method of introducing a sulfonic acid group or a sulfonic acid metal base as an aqueous polar group.

First, a diisocyanate compound having two functional groups (-NGO) has a sulfonic acid group or a sulfonic acid metal base, and one functional group (-NGO) of the diisocyanate compound has a sulfonic acid group or a sulfonic acid metal base.
After reacting a compound having an active hydrogen capable of reacting with O) to obtain a compound having an -NGO group and a sulfonic acid group or a sulfonic acid metal group in one molecule, the -NGO group in the above compound and the phenoxy It can be introduced by reacting with hydroxyl groups present in the resin.

Examples of the compound having the above-mentioned sulfonic acid group or sulfonic acid metal base and having active hydrogen capable of reacting with -Ncod of the above-mentioned diisocyanate compound include the following compounds.

■H,N-5(h)I ■HOOC-CI(!~SO,ll ■HO-CHx-SO3Na @HO-(CHi)t-3OsNa oI(o-(C)It)-5OJ On the other hand, diisocy Examples of the nate compounds include methylphenyl diisocyanate, hexamethylene diisocyanate, tetraethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, m-phenylene diisocyanate, and p-phenylene diisocyanate. Diisocyanate, 2゜4-tolylene diisocyanate, 2.6-)lylene diisocyanate, 1,3-xylene diisocyanate, 1,5-naphthalene diisocyanate, 4.4'
-diphenylmethane diisocyanate, 3゜3-dimethyl-4,4'-diphenylmethane diisocyanate, 4
,4. -diphenylmethane diisocyanate, 3.3-
Dimethyl-4,4-diphenylmethane diisocyanate, 3,3-dimethylbiphenylene diisocyanate, citrilene soocyanate, dianisidine diisocyanate, and the like.

The reaction of the above diisocyanate compound with a compound having the above-mentioned sulfonic acid group or sulfonic acid metal base and having an active hydrogen that can react with the -NGO group of the above-mentioned diisocyanate compound is as follows. become that way.

For example, the reaction between hydroxymethylsulfonic acid and tolylene diisocyanate is as follows.

When a compound having a group capable of reacting with active hydrogen and a sulfonic acid group or a sulfonic acid metal base is reacted with a phenoxy resin, the 1NGO group remaining in the former and the 10H group in the phenoxy resin are reacted. A phenoxy resin into which a sulfonic acid group or a sulfonic acid metal base, which is a hydrophilic polar group, is introduced is obtained.

The specific reaction formula is as follows.

(A-2) A method of introducing a hydrophilic polar group by dechlorination reaction.

That is, a compound containing a hydrophilic polar group and chlorine in the molecule and a phenoxy resin having a polyfunctional OH group are dissolved in a solvent such as dimethylformamide or dimethyl sulfoxide in which both components are soluble, and lysine, Amines such as picoline and triethylamine: There is a method of introducing a hydrophilic polar group through a dechlorination reaction between an 10H group and chlorine in the presence of a dehydrochlorination agent such as an epoxy compound such as ethylene oxide or propylene oxide. The reaction formula is as follows.

+ CI (CHg) zsOJa + MCI In the phenoxy resin synthesized as described above in which a woody polar group is introduced into the side chain, the introduction equivalent of the polar group is 1
It is preferably within the range of 000 to tooooo,
When the introduced light is less than 11,000, the dispersibility of the magnetic powder deteriorates, and when it is more than 100,000, the solubility in solvents deteriorates and the moisture resistance of the coating film deteriorates.

In addition, the molecular weight of the above phenoxy resin is preferably within the range of 1000 to 100000 when preparing a magnetic paint. If this molecular weight is less than 1000, durability will be poor, and if it is more than 100000, it will be difficult to dissolve in a solvent. The quality deteriorates.

Next, a method for introducing an electron beam sensitive double bond into a phenoxy resin will be shown. The electron beam sensitive double bond can be introduced by the following method.

B. A method of introducing an electron beam sensitive double bond by modifying the 10H group remaining in a phenoxy resin containing a sulfonic acid group or a sulfonic acid metal base.

In this method, in order to modify the above-mentioned -OH group, a functional group capable of reacting with the active hydrogen of the -OH group is directly reacted with a compound having an electron beam-sensitive double bond, or an active hydrogen and an electron-beam sensitive double bond are reacted. A compound having a double bond and a diisocyanate compound are reacted in equimolar amounts to obtain a reaction product resulting from the reaction between one of the -NGO groups of the diisocyanate compound and the above active hydrogen, and then a phenol resin What is necessary is to react the H group with the other remaining NCo group of the above reaction product.

(B-1) A method in which a compound having a sensitive group capable of reacting with the active hydrogen of the -OH group and an electron beam sensitive double bond is directly used.

Examples of compounds that can directly act on the 10H group of the phenoxy resin include compounds having an epoxy group or an aziridinyl group and an electron beam sensitive double bond, such as the following compounds (a), ( b),
(0 is included.

(However, in the formula, R represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 8.) Among these, 2-(1-aziridinyl)ethyl methacrylate, allyl-2-aziridinylpropionate, Preferably, glycidyl meccrylate or the like is used.

If these compounds are allowed to act directly on the 10H group of the phenoxy resin, an electron beam sensitive double bond will be introduced.

(B-2) A method of reacting a reaction product of a diisocyanate compound and active hydrogen with a phenoxy resin.

On the other hand, as compounds having active hydrogen and an electron beam-sensitive double bond used when introducing an electron beam-sensitive double bond via the above-mentioned diisocyanate compound, acrylic acid,
Methacrylic acid, acrylic acid or hydroxyalkyl esters such as hydroxymethyl ester, 2-hydroxyethyl ester, 3-hydroxypropyl ester, 4-hydroxybutyl ester, 8-hydroxyoctyl ester of methacrylic acid, acrylamide, methacrylamide, N -methylol acrylamide, N-methylol methacrylamide, and the like.

As the diisocyanate compound that reacts with the compound having active hydrogen and electron beam sensitive double bonds, those mentioned above can be used.

For example, a method of reacting a compound having an active hydrogen and an electron beam-sensitive double bond with a diisocyanate compound and modifying and introducing the reaction product into an 10H group of a phenoxy resin is described. When shown using nato, it becomes as follows.

Next, a reaction will be shown in which the above reaction product is modified into an 10H group of a phenoxy resin and introduced.

In the phenoxy resin synthesized as described above and having an electron beam-sensitive double bond introduced into its side chain, the introduction equivalent of the compound having an electron beam-sensitive double bond is preferably 500 to 50,000, and the introduction equivalent is 500. In the following cases, the dispersibility of the magnetic powder deteriorates, and in cases of 50,000 or more, the solubility in solvents deteriorates and the moisture resistance of the coating film deteriorates.

The above phenoxy resin into which an electron beam sensitive double bond and a sulfonic acid group or a sulfonic acid metal base have been introduced may be used in combination with other binders. As such a binder, those conventionally used as a binder for magnetic recording media can be used, including vinyl chloride-vinyl acetate copolymer,
Vinyl chloride-vinyl acetate rubinyl alcohol copolymer, hinyl chloride-acetic acid and nyl-maleic acid copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic acid ester-acrylonitrile copolymer, Acrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer, thermoplastic polyurethane resin, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer 5 Butadiene-acrylonitrile Copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, polyvinyl butyral.

Examples include cellulose derivatives, styrene-butadiene copolymers, polyester resins, phenol resins, epoxy resins, thermosetting polyurethane resins, urea resins, melamine resins, alkyd resins, urea-formaldehyde resins, and mixtures thereof.

Among these, polyurethane resins, polyester resins, acrylonitrile butadiene copolymers, etc., which are said to impart flexibility, are preferred.

In the magnetic recording medium of the present invention, the magnetic layer is formed by coating the surface of the non-magnetic support with a magnetic paint prepared by dispersing ferromagnetic powder in the above-mentioned binder and dissolving it in organic solution 7FIJ. Ru.

Here, the material for the non-magnetic support may be any material that is normally used in this type of magnetic recording medium, such as polyesters such as polyethylene terephthalate, polyolefins such as polyethylene, polypropylene, etc. cellulose derivatives such as cellulose triacetate, cellulose diacetate, and cellulose acetate butyrate; vinyl lubricants such as polyvinyl chloride and polyvinylidene chloride; plastics such as polycarbonate, polyimide, polyamide, and polyamideimide;
Examples include paper, metals such as aluminum and copper, light alloys such as aluminum alloys and titanium alloys, ceramics, and single crystal silicon. Examples of the forms of this non-magnetic support include film and tape.

It may be a sheet, disk, card, drum, etc.

Moreover, any ordinary ferromagnetic powder can be used as the ferromagnetic powder used in the magnetic layer. Therefore, ferromagnetic powders that can be used include ferromagnetic iron oxide particles,
Examples include ferromagnetic chromium dioxide, ferromagnetic alloy powder, hexagonal barium ferrite fine particles, iron nitride, and the like.

The above-mentioned ferromagnetic iron oxide particles are those whose X value is in the range of 1.33≦X≦1.50 when expressed by the general formula FeOx, that is, magnetite (γ-Fe, Os).

X-1,50), magnetite (Fe204.
= 1.33) and their solid solutions (FeOx, 1.3
3 < There are two types.

The above-mentioned ferromagnetic chromium dioxide may include CrO, or Ru and Sn for the purpose of improving coercive force thereof.

A material containing at least one of Te, Sb, Fe, Ti, V, Mn, etc. can be used.

Examples of the ferromagnetic alloy powder include Fe, Co, and Ni.

Fe-Co, Fe-Ni, Fe-Co-Ni, C.

-Ni, Fe-Co-B, Fe-Co-Cr-B.

Mn-B1. Mn-Al, Fe-Co-V, etc. can be used, and in order to improve various properties, Al, Si
, Ti, Cr, Mn, Cu, Zn, and other metal components may be added.

In addition to the binder and ferromagnetic powder, the magnetic layer also contains additives such as a dispersant, a lubricant, an abrasive, an antistatic agent,
Rust inhibitors and the like may also be added.

The constituent materials of the magnetic layer described above are prepared as a magnetic paint by dissolving it in an organic solvent and coated on a non-magnetic support.The solvent for the magnetic paint may be acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. Ketones, esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, acetic acid glycol monoethyl ether, glycol ethers such as glycol dimethyl ether, glycol monoethyl ether, dioxane, etc.
Aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as hexane and heptane, methylene chloride and ethylene chloride.

Tetramerized carbon i, chloroform, ethylene chlorohydrin,
Examples include chlorinated hydrocarbons such as dichlorobenzene.

[Effect]

The sulfonic acid group or sulfonic acid metal base introduced into the phenoxy resin exhibits excellent affinity for magnetic powder. Therefore, by using a phenoxy resin into which a sulfonic acid group or a sulfonic acid metal base is introduced as a binder, even ultrafine magnetic powder or magnetic powder with a large amount of magnetization can be dispersed well.

Further, the electron beam sensitive double bond introduced into the phenoxy resin is easily cleaved by irradiation with an electron beam or the like, and the resulting polymerization reaction cures the coating film.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

First, a phenoxy resin containing an electron beam sensitive double bond and a sulfonic acid group or a sulfonic acid metal base in its molecule was synthesized.

Synthesis Example 1 Sodium p-hydroxybenzenesulfonate and tolylene diisocyanate are reacted to form -NC○ group and -5Os.
Monomers a each having one Na group were obtained. This monomer a is mixed with 100% of phenoxy resin with a molecular weight of 10,000.
A broadly reactive polymer A was synthesized in proportions of dffi to parts by weight.

Next, hydroxyethyl acrylate and tolylene diisocyanate were reacted to obtain monomer b having one -NGO group and one acrylic group. Polymer B was synthesized by reacting 3 parts by weight of this monomer b with the above polymer A100Iiffi part.

Synthesis Example 2 Monomer a obtained in the same manner as Synthesis Example 1 had a molecular weight of 1000.
Polymer C was synthesized by reacting 199 parts by weight with 100 parts by weight of phenoxy resin.

Next, 3 parts by weight of monomer b obtained in the same manner as in Synthesis Example 1 was reacted with 3 parts by weight of the above polymer Cl0Q to synthesize polymer D.

Synthesis Example 3 Nanatsumer-a obtained in the same manner as Synthesis Example 1 had a molecular weight of 2000.
Polymer E was synthesized by reacting 199 parts by weight with 100 parts by weight of phenoxy resin.

Next, 155 parts by weight of monomer b obtained in the same manner as in Synthesis Example 1 was reacted with 100 parts by weight of the above polymer A to synthesize polymer F.

Synthesis Example 4 Nanatsumer-a obtained in the same manner as Synthesis Example 1 had a molecular weight of 5000.
Polymer G was synthesized by reacting 0.8 parts by weight with 100 parts by weight of phenoxy resin.

Next, 0.6 parts by weight of monomer b obtained in the same manner as in Synthesis Example 1 was reacted with 100 parts by weight of the above polymer 0 to synthesize polymer H.

Synthesis Example 5 Monomer a obtained in the same manner as Synthesis Example 1 had a molecular weight of 1000.
Polymer A was synthesized by reacting 4 parts by weight with 100 parts by weight of the phenoxy resin.

Next, 6 parts by weight of monomer b obtained in the same manner as in Synthesis Example 1 was reacted with 100 parts by weight of the above polymer A to synthesize polymer (2).

Synthesis Example 6 Monomer a obtained in the same manner as Synthesis Example 1 had a molecular weight of 1000.
Polymer K was synthesized by reacting 388 parts by weight with 100 parts by weight of phenoxy resin.

Next, 3 parts by weight of monomer b obtained in the same manner as in Synthesis Example 1 was reacted with 100 parts by weight of the above polymer to synthesize polymer L.

Synthesis Example 7 Monomer a obtained in the same manner as Synthesis Example 1 had a molecular weight of 5000.
0.4mff per 100 parts by weight of phenoxy resin
A portion of the mixture was reacted to synthesize Polymer M.

Next, 3 parts by weight of monomer b obtained in the same manner as in Synthesis Example 1 was reacted with 100 parts by weight of the above polymer A to synthesize polymer N.

Synthesis Example 8 Monomer a obtained in the same manner as in the synthesis example had a molecular weight of 5000.
Polymer G was synthesized by reacting 0.8 parts by weight with 100 parts by weight of phenoxy resin.

Next, 0.3 parts by weight of monomer B obtained in the same manner as in Synthesis Example 1 was reacted with 100 parts by weight of the above polymer G to synthesize Polymer 0.

Next, polymers B and D obtained in the above synthesis examples.

A magnetic recording medium was produced using F, H, I, L, N, and O.

Example 1 Polymer B' 12 parts by weight Polyester polyurethane resin 8 parts by weight (manufactured by Polyurethane Kogyo Co., Ltd., N-2304) Lubricant (dimethyl silicone oil) 1 part by weight Lubricant (hexyl laurate) IH5t partial dispersant (lecithin)
1M portion abrasive (Crabs)
3 parts by weight antistatic agent (carbon)
2 parts by weight methyl ethyl ketone
100 parts by weight methyl isobutyl ketone
50 parts by weight toluene 50
Part by Weight The above composition was mixed in a ball mill for 48 hours, filtered through a filter, a curing agent was added, and further mixed for 30 minutes, and this was coated on a polyethylene terephthalate film with a thickness of 16 μm so that the film thickness after drying was 6 pm. Then, after performing a magnetic field orientation treatment, it was dried and rolled up. After calendering this, it was cut into 1/2 inch width to obtain a sample tape.

Example 2 A sample tape was produced in the same manner as in Example 1 except that Polymer D was used instead of Polymer B in Example 1.

Example 3 A sample tape was produced in the same manner as in Example 1 except that Polymer F was used instead of Polymer B in Example 1.

Example 4 A sample tape was produced in the same manner as in Example 1 except that Polymer H was used instead of Polymer B in Example 1.

Example 5 A sample tape was prepared in the same manner as in Example 1 except that Polymer 1 was used instead of Polymer B in Example 1.

Example 6 A sample tape was produced in the same manner as in Example 1 except that Polymer L was used instead of Polymer B in Example 1.

Example 7 A sample tape was produced in the same manner as in Example 1 except that Polymer N was used instead of Polymer B in Example 1.

Example 8 A sample tape was produced in the same manner as in Example 1 except that Polymer ○ was used instead of Polymer B in Example 1.

Comparative Example Hydroxyethyl acrylate and tolylene diisocyanate were reacted, and -NGO group and acrylic group were each converted to 1
A monomer b having each monomer was obtained. Polymer P was synthesized by reacting 3 parts by weight of this monomer b with 100 parts by weight of a phenoxy resin having a molecular weight of 10,000.

In Example 1, the above polymer P was used instead of polymer B.
A resample tape was prepared in the same manner as in Example 1 except for the following.

For each of the sample tapes obtained, the surface gloss, shedding, and still characteristics were measured.

In addition, the above surface gloss is the gloss needle (GLO5S?IIE
TER) under the conditions of an incident angle of 75'' and a reflection angle of 75''. Further, powder falling was evaluated by visually observing the amount of falling powder on the head drum, guide, etc. after running the shuttle 100 times for 60 minutes, and using a point deduction method (-5 to 0). The still characteristics were determined by recording a 4.2 MB2 video signal on a sample tape and measuring the time until the playback output attenuated to 50%. The results are shown in the table below.

(The following is a blank space) From this table, it can be seen that each sample tape according to the present invention not only has excellent surface gloss and FA removal, but also has significantly improved still characteristics.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
Since phenoxy resin containing a sulfonic acid group or a sulfonic acid metal base in the molecule is used as a binder for the magnetic layer, it has a high affinity for magnetic powder, even if it is an ultra-fine magnetic powder or a magnetic material with a large amount of magnetization. Even if it is a powder, it has good dispersibility. Therefore, the durability and surface properties of the obtained magnetic recording medium are improved, and the electromagnetic conversion characteristics are also extremely excellent.

In addition, since the above-mentioned binder has an electron beam double bond in its molecule, magnetic paint can be easily cured by electron beam irradiation, which greatly simplifies the manufacturing process and reduces the pot life and solidification of the paint. There are also great process advantages, such as improved properties.

Patent applicant: Sony Corporation Agent Patent Attorney Akira Koba Oka Art supplies Sakae Proceeding Officer (Volunteer) November 4, 1986

Claims (1)

[Scope of Claims] A magnetic recording medium in which a magnetic layer mainly composed of ferromagnetic powder and a binder is formed on a non-magnetic support, wherein the magnetic layer has an electron beam sensitive double bond and a sulfone bond in its molecules. A magnetic recording medium characterized in that it contains a phenoxy resin containing an acid group or a sulfonic acid metal base as a binder.