JPS6363126A - 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 quaternary ammonium salt 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 quaternary ammonium salt 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 Gil layer mainly composed of ferromagnetic powder and a binder is formed on a non-magnetic support, in which the magnetic layer has an electron beam sensitive double bond and a fourth bond in the molecule. By containing a phenoxy resin containing grade ammonium salt as a binder, it is possible to improve the coagulation of the solid content of the paint, increase the pot life, and simplify the manufacturing process, as well as improve the dispersibility of the magnetic powder and the surface properties of the magnetic layer. The durability of the magnetic recording medium obtained by improving the
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, satisfactory dispersibility and surface area cannot be obtained with the above-mentioned binders, which increases the banking density of magnetic powder. It has also become difficult. Therefore, durability and magnetic properties 8 and electromagnetic conversion properties were also insufficient. In particular, the performance has been insufficient for ultrafine magnetic powders that are compatible with high-density recording 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 coating, the method of applying heat or adding a curing agent to accelerate polymerization is adopted, but there are limitations due to the magnetism of the solid content of the paint, pot life, etc. There are many
Workability is worsened.

[Problem that the invention seeks to solve]

In this way, the conventionally used vinyl chloride copolymers have many problems to be solved in terms of dispersibility for magnetic powder, physical properties of coatings, and handling during manufacturing, and it is difficult to achieve a certain level of durability. It was difficult to ensure good , iffff properties, and electromagnetic conversion characteristics.

Therefore, the present invention has been proposed to solve the above-mentioned drawbacks in the technical field, and aims to improve the properties of the coating film when formed as a dispersible 1Mi layer for magnetic powder, and the workability during coating film formation. It is an object of the present invention to provide a binder having excellent properties in these respects, and to provide a magnetic recording medium with excellent surface properties and durability, and good magnetic properties and IT electromagnetic conversion properties.

c) Means for Solving Problems] The present inventors have discovered that high affinity for magnetic powder is exhibited by introducing a quaternary ammonium salt into the side chain as a polar group, and that electron beam sensitive secondary The present invention was completed based on the fact that the introduction of double bonds is effective in improving workability, and the present invention is based on the fact that the introduction of double bonds is effective in improving workability. A magnetic recording medium having a magnetic layer formed thereon, characterized in that the magnetic layer contains as a binder a phenoxy resin containing an electron beam sensitive double bond and a quaternary ammonium salt in its molecules. It is.

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 quaternary ammonium salt 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 to activate the It may be modified with a compound having a group capable of reacting with hydrogen and a quaternary ammonium salt in the molecule.

A, @Method of introducing a quaternary ammonium salt as an aqueous polar group.

A diisocyanate compound having two functional groups (-NGO) has a quaternary ammonium salt, and one functionality of the diisocyanate compound! After reacting a compound having an active hydrogen capable of reacting with (-NGO) to obtain a compound having an -NGO group and a quaternary ammonium salt in one molecule, the -NGO group in the above compound and the phenoxy resin This is a method of introducing it by reacting with the hydroxyl groups present in it.

Examples of the compound having the above-mentioned quaternary ammonium salt and having an active hydrogen capable of reacting with the -NGO group of the above-mentioned diisocyanate compound include the following compounds.

■((CHs)J'CIhCHtO)I) ) CI-
■((CHs)J”CHzCHzOH) ) Br-■
((C)I*) sN″CHzCHzOOCNHz)
CI-■((co3)iN“CtltC)l(CHz)
OH) I −■ 11□NCbHaN” (CH3)
al-・HCI■(HOCHgC)IzN”(CJs
)z) I - On the other hand, as the diisocyanate compound, methylphenyl diisocyanate, hexamethylene diisocyanate, tetraethylene diisocyanate,
Inphorone diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, m-phenylene diisocyanate, p-phenylene 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 diisocyanate, 3,3-dimethyl-4,4-diphenylmethane diisocyanate, 3,3-dimethylbiphenylene diisocyanate, ditolylene diisocyanate, dianisidine diisocyanate, and the like.

The reaction of the above diisocyanate compound with a compound having the above quaternary ammonium salt and having an active hydrogen capable of reacting with -NCO5 of the above diisocyanate compound is as follows. .

For example, the reaction between β-hydroxyethyltrimethylammonium bromide and tolylene diisocyanate is as follows.

When a compound having a group capable of reacting with active hydrogen and a quaternary ammonium salt in its molecule is reacted with a phenoxy resin, the 1NGO group remaining in the former reacts with the 10H group in the phenoxy resin. Then, a phenoxy resin into which a quaternary ammonium salt, which is a hydrophilic polar group, is introduced is obtained.

The specific reaction formula is as follows.

C・0 In the phenoxy resin synthesized as described above, in which a hydrophilic 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 100000.

If the introduced light is less than 11,000, the dispersibility of the magnetic powder will be poor, and if it is more than 1000, the solubility in the solvent will be deteriorated and the moisture resistance of the coating film will be deteriorated.

Furthermore, the molecular weight of the phenoxy resin is preferably within the range of 1,000 to 100,000 when preparing a magnetic coating material. If the molecular weight is less than 1,000, durability will be poor, and if it is more than 100,000, solubility in solvents will deteriorate.

Next, the following method may be used to introduce an electron beam sensitive double bond, which shows a method for introducing an electron beam sensitive double bond into a phenoxy resin.

B. A method of introducing an electron beam sensitive double bond by modifying the 10H group remaining in the phenoxy resin into which a quaternary ammonium salt has been introduced.

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 by the reaction between one of the -NGO groups of the diisocyanate compound and the above active hydrogen, and then a reaction product is obtained by the reaction of one of the -NGO groups of the diisocyanate compound with the above active hydrogen. What is necessary is to react the H group with the other remaining NCO group of the above reaction product.

CB-1) A method in which a functional group capable of reacting with the active hydrogen of the -OH group and a compound having an electron beam-sensitive double bond are brought into direct contact with each other.

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),
(c) is mentioned.

(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 methacrylate or the like is used.

If these compounds are made to act directly on the 10H group of a 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 containing 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.

First, the reaction between a compound containing active hydrogen and an electron beam-sensitive double bond and a diisocyanate compound will be described.

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 500 or more, the solubility in solvents deteriorates and the moisture resistance of the coating film deteriorates.

The phenoxy resin into which the electron beam sensitive double bond and quaternary ammonium salt are introduced may be used in combination with other binders. As such a binder, those conventionally used as binders for magnetic recording media can be used, including vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride -vinyl acetate-maleic acid copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer,
Acrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer 9 thermoplastic polyurethane resin, polyvinyl fluoride, vinylidene chloride-7 crylonitrile copolymer , butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, polyvinyl butyral, cellulose SA 5 bodies.

Examples include styrene-butadiene copolymer, polyester resin, phenol resin, epoxy resin, thermosetting polyurethane resin, urea resin, melamine resin, alkyd resin, urea-formaldehyde resin, and mixtures thereof. Among these, polyurethane resins, polyester resins, acrylonitrile buxene 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, for example, dispersing ferromagnetic powder in the above-mentioned binder and dissolving it in an organic solvent.

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 resins such as polyvinyl chloride and polyvinylidene chloride; plastics such as polycarbonate, polyimide, polyamide, and polyamideimide;
Paper, aluminum, metals such as W4, aluminum alloys,
Examples include light alloys such as 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 have a value of X in the range of 1.33≦X≦1.50 when expressed by the general formula FeOx, that is, magnetite Cr FezO3.

X=1.50), magnetite (FeiOa,
X ” 1.33) and their solid solutions (FeOx, 1
．． 33<X<1.50). Furthermore, cobalt may be added to these ferromagnetic iron oxides for the purpose of increasing coercive force. There are two types of cobalt-containing iron oxides: doped type and deposited type.

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-Al1. Fe-Co-V, etc. can be used, and A1 can be used to improve various properties of these.
．． Metal components such as Si, Ti, Cr, Mn, Cu, and Zn 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. Ketone type, ester type such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, acetic acid glycol monoethyl ether, glycol ether type such as glycol dimethyl ether 3 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.

Carbon tetrachloride, chloroform, ethylene chlorohydrin,
Examples include chlorinated hydrocarbons such as dichlorobenzene.

[Effect]

The quaternary ammonium salt introduced into the phenoxy resin is
Demonstrates excellent affinity for magnetic powder. Therefore, by using the phenoxy resin into which this quaternary ammonium salt 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 quaternary ammonium salt in its molecule was synthesized.

Synthesis Example 1 β-hydroxyethyltrimethylammonium and tolylene diisocyanate were reacted to obtain monomer a having one each of -NGO group and quaternary ammonium salt. 3.6 parts by weight of this monomer a was reacted with 100 parts by weight of a phenoxy resin having a molecular weight of 10,000 to synthesize polymer 8.

Next, hydroxyethyl acrylate and tolylene diisocyanate were reacted to obtain monomer b having one -Nco group and one acrylic group. Polymer B was synthesized by reacting 3 parts by weight of this monomer b with 100 parts by weight of the above polymer A.

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 188 parts by weight with 100 parts by weight of the 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 0 to synthesize polymer D.

Synthesis Example 3 Monomer a obtained in the same manner as Synthesis Example 1 had a molecular weight of 2000.
Polymer E was synthesized by reacting 188 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 8100 parts by weight of the above polymer to synthesize polymer F.

Synthesis Example 4 Monomer a obtained in the same manner as Synthesis Example 1 had a molecular weight of 5ooo.
Polymer G was synthesized by reacting 0.7 parts by weight with 100 parts by weight of the phenoxy resin of o.

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 G 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 3.6 parts by weight with 100 parts by weight of phenoxy resin.

Next, 6 parts by weight of Shitsummer-b obtained in the same manner as in Synthesis Example 1 was reacted with 100 parts by weight of the above-mentioned 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 36 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 was converted into molecules ■5ooo
Polymer M was synthesized by reacting 0.4 parts by weight with 100 parts by weight of the phenoxy resin of o.

Next, 0.61 i part of monomer b obtained in the same manner as in Synthesis Example I was reacted with 100 parts by weight of the above polymer A to synthesize polymer N.

Synthesis Example 8 Nanatsumer-a obtained in the same manner as Synthesis Example 1 had a molecular weight of 5ooo.
Polymer G was synthesized by reacting 0.7 parts by weight with 100 parts by weight of the phenoxy resin.

Next, monomer b obtained in the same manner as in Synthesis Example 1 was added to the above polymer G100! ! Polymer O was synthesized by reacting 0.3 ffim part with respect to that amount.

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 8 12 parts by weight of lubricant (dimethyl silicone oil) 1 part by weight of lubricant (
hexyl laurate) 1 part by weight dispersant (lecithin) 1 part by weight abrasive (crzo
x) 3 parts by weight antistatic agent (carbon) 2 parts by weight methyl ethyl ketone
10 caps 1 part Methyl isobutyl ketone
50 parts by weight toluene
50 parts by weight The above composition was mixed in a ball mill for 48 hours, filtered through a filter, a curing agent was added, further mixed for 30 minutes, and this was coated on a 16 μm thick polyethylene terephthalate film with a film thickness of 6 μm after drying. It was applied so that Next, after performing a magnetic field orientation treatment, it was dried and wound up. After calendaring this, 1/2
The sample tape was cut into inch width pieces.

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 produced 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 0 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. This monomer b is molecule f
Polymer P was synthesized by reacting 3 parts by weight with 100 parts by weight of the phenoxy resin of ftloooo.

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

Surface gloss, powder removal, and still characteristics were measured for each sample tape obtained.

The above surface gloss was measured using a gloss meter (GLO3S METI).
ER) under the conditions of an incident angle of 75'' and a reflection angle of 75°.In addition, the amount of powder falling on the head drum, guide, etc. was visually observed after running the shuttle 100 times for 60 minutes. The still characteristics were evaluated using the deduction method (-5 to 0).A 4.2MHz video signal was recorded on a sample tape, and the still characteristics were
The time taken for the reproduction output to decay to 50% was taken as the time. The results are shown in the table below.

(The following is a blank space) This table also shows that each sample tape according to the present invention not only has excellent surface gloss and powder removal, but also has significantly improved still characteristics.

(Effect of the invention) As is clear from the above explanation, in the present invention,
Since phenoxy resin containing quaternary ammonium salt in the molecule is used as a binder for the magnetic layer, it has a high affinity for magnetic powder, even if it is ultra-fine magnetic powder or magnetic powder with a large amount of magnetization. However, the dispersibility is good. Therefore, the durability and surface properties of the obtained magnetic recording medium are improved, and the magnetic conversion properties are also extremely excellent.

In addition, since the above-mentioned binder has an electron-sensitive 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 paint. There are also great process advantages, such as improved properties.

Patent Applicant Sony Corporation Agent Patent Attorney Kodo Kobu Ensou Sakae - Procedure Nagi 1↑Sho 1 Shooting (Voluntary) November 4, 1985 Commissioner of the Japan Patent Office Black 1) Meiji J1 Tono 1, Incident Display Showa 1961 Patent Application No. 207313 2, Name of the invention Magnetic recording medium 3, Relationship with the case of the person making the amendment Patent applicant address 6-7-35, Kitashina-yo, Kitashinyo-ku, Tokyo Name (2
18) Sony Corporation Representative Ohga
6, subject of amendment 7, statement of contents of amendment 15, line 111 to line 10 from the bottom, “a”
The dispersibility of the f-type powder has deteriorated.''
The durability of the paint film deteriorated.''

In the 100th line to the 8th line from the bottom of page 15 of the specification date, the statement "The solubility in solvents deteriorates and the moisture resistance of the coating film deteriorates." ``sexuality deteriorates.''

On page 25 of the specification, from the 6th line from the bottom to the 5th line from the bottom, the statement ``add a curing agent and mix for an additional 30 minutes'' is deleted.

In the second line from the bottom to the first line from the bottom of No. 25 of the specification, the statement ``After calendering this'' is amended to read ``After irradiating this with an electron beam and calendering.''

that's all

Claims (1)

[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 electron beam sensitive double bonds and a bond in its molecules. A magnetic recording medium characterized by containing a phenoxy resin containing a quaternary ammonium salt as a binder.