JPH01319122A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To develop a crosslinked structure between a vinyl chloride copolymer having an epoxy group and a polyurethane resin having a mercapto group and to provide good durability to the recording medium by incorporating the above-mentioned vinyl chloride copolymer and polyurethqane resin into a binder. CONSTITUTION:The vinyl chloride copolymer having the epoxy group and the polyurethane resin having the mercapto group are incorporated into the binder on a nonmagnetic base. The vinyl chloride copolymer having the epoxy group is the compd. essentially consisting of a vinyl chloride compd. and is formed by copolymerizing the epoxy group introduced therein in order to form the crosslinked structure and a monomer having the double bonds copolymerizable with the vinyl chloride compd. On the other hand, the polyurethane resin having the mercapto group is formed by introducing the mercapto group into the polyurethane resin. The binder which develops the good crosslinked structure without being affected by moisture is obtd. in this way and the magnetic recording medium having the excellent durability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to magnetic recording media such as magnetic tapes, and particularly to improving the durability thereof.

[Summary of the invention]

The present invention relates to a magnetic recording medium in which a magnetic layer mainly consisting of ferromagnetic powder and a binder is formed on a non-magnetic support, in which a chloride compound having an epoxy group in the molecule is used as the binder constituting the magnetic layer. The present invention aims to provide a magnetic recording medium with excellent durability by using a vinyl copolymer and a polyurethane resin having a mercapto group.

[Conventional technology]

In recent years, magnetic recording media, especially magnetic recording media for VTRs (video tape recorders), are required to have improved magnetic properties, electromagnetic conversion properties, etc. in order to obtain high playback output even when recording at short wavelengths. ing. Therefore, efforts have been made to make the magnetic powder particles finer and to increase the magnetic force, and the packing density of the magnetic powder in the magnetic layer has increased.

There is a growing tendency to increase so-called backing density.

By the way, as described above, when the backing density of the magnetic powder increases, the ratio of the binder in the magnetic coating film decreases significantly, which may cause peeling of the magnetic layer when used as a magnetic recording medium, for example. There is a risk that the strength of the magnetic coating film will deteriorate. Therefore, in order to prevent such strength deterioration of the magnetic coating film, it is necessary to improve the strength of the binder that constitutes the coating film.

From this situation, magnetic! ! ! It has been proposed to improve the mechanical strength of the magnetic coating by crosslinking the binder in the binder. Alternatively, a crosslinked structure is formed by utilizing the reaction between active hydrogen of a hydroxyl group in a molecule and an isocyanate.

However, the above-mentioned binder made of a compound having an electron beam-sensitive bond requires extremely expensive equipment in order to form a crosslinked structure, and is therefore impractical.

On the other hand, with a binder in which the active hydrogen of the hydroxyl group reacts with an incyanate compound etc. to form a crosslinked structure, -NCO+
While the intended reaction is -011--NHCO-, in reality, -NCO+11!0 → -NH! The isocyanate group preferentially reacts with water, as shown by the reaction formula +COx, and the generated amino group reacts with other isocyanate groups, as shown by the following formula: This causes the inconvenience of being lost. In other words, when attempting to form a crosslinked structure through the reaction between an isocyanate compound and a hydroxyl group, the isocyanate group in particular is easily affected by moisture, and the inocyanate group that substantially contributes to crosslinking decreases, resulting in insufficient crosslinking. There is a possibility that the structure cannot be formed.

[L that the invention tries to solve! IB]

As mentioned above, the mechanical strength of the coating film is increased by forming a crosslinked structure using the reaction between the binder and incyanate and the hydroxyl group, which forms a crosslinked structure through electron beam sensitive bonding and increases the mechanical strength of the coating film. Binders, etc., have problems such as being impractical due to equipment issues, and the reaction itself being susceptible to moisture and not forming a good crosslinked structure.
Magnetic recording media using these as binders have some drawbacks, such as insufficient durability.

Therefore, the present invention was proposed to solve the above-mentioned drawbacks in the technical field, and provides a binder that exhibits a good crosslinked structure without being affected by moisture when forming a crosslinked structure. The purpose of this invention is to provide a magnetic recording medium with excellent durability.

[Means to solve the problem]

As a result of extensive research over a long period of time in order to achieve the above-mentioned objectives, the present inventors have found that a binder consisting of a vinyl chloride copolymer having an epoxy group in the side chain and a polyurethane resin having a mercapto group is an excellent binder. The present invention was completed based on the discovery that it exhibits excellent crosslinking properties and is very effective in improving the durability of coating films.

That is, the present invention provides a magnetic recording medium in which a magnetic layer mainly consisting of a ferromagnetic powder and a binder is formed on a non-magnetic support, wherein the binder is a vinyl chloride copolymer having an epoxy group; It is characterized by containing a polyurethane resin having a mercapto group.

Here, the vinyl chloride copolymer containing epoxy groups is
It is mainly composed of a vinyl chloride compound, and is made by copolymerizing an epoxy group introduced into this to form a crosslinked structure and a monomer having a double bond that can be copolymerized with a vinyl chloride compound. It is something.

Examples of the vinyl chloride compounds constituting the vinyl chloride copolymer include vinyl chloride, vinyl acetate, vinyl propionate, vinyl alcohol, methyl vinyl ether, isobutyl vinyl ether, cetyl vinyl ether, and other vinyl thread-forming (meth)acrylic acids. Methyl, ethyl (meth)acrylate.

Propyl (meth)acrylate, isopropyl (meth)allylate, butyl (meth)acrylate.

(meth)acrylic acid lauryl, (meth)acrylic acid-
Examples include acrylic monomers such as 2-hydroxypropyl, 2-hydroxyethyl methacrylate, and 2-hydroxyethyl acrylate acrylic acid ester, and vinylidene monomers such as vinylidene chloride and vinylidene fluoride. One or more of these monomers can be copolymerized. are available.

In addition, examples of monomers having a double bond copolymerizable with the vinyl compound and having an epoxy group introduced to form a crosslinked structure include unsaturated monomers such as allyl glycidyl ether and methacryl glycidyl ether. Alcohol glycidyl ethers, glycidyl acrylate 2
Glycidyl esters of unsaturated acids such as glycidyl methacrylate, glycidyl-p-vinyl benzoate, methylglycidyl itaconate, glycidyl ethyl maleate, glycidyl vinyl sulfonate 2-glycidyl (meth)allylsulfonate, butadiene monoxide, vinylcyclohexene monoxide, 2-methyl-5,6
- Epoxide olefins such as epoxyhexene and the like can be mentioned.

Furthermore, the vinyl copolymer may be copolymerized with other monomers having double bonds that can be copolymerized with the vinyl compound in order to improve its properties. , for example, butadiene threads such as 1,3-butadiene, maleic acid.

Maleic anhydride, diethyl maleate, butylbenzyl maleate, di-2-hydroxyethyl maleate,
Dimethyl itaconate, styrene, α-methylstyrene,
Examples include p-methylstyrene, acrylonitrile, ethylene, propylene, and the like.

The amount of epoxy groups contained in the vinyl copolymer is preferably about 0.05 to 2.0 mmol/g. If the amount of epoxy groups is less than the above-mentioned range, the crosslinked structure will be insufficient and the durability will deteriorate; if it is too much, problems such as poor handling and difficulty in forming into a coating will occur.

On the other hand, a polyurethane resin having a mercapto group is one in which a mercapto group is introduced into a polyurethane resin.

Here, any conventionally known polyurethane resin can be used as the main polyurethane resin, and examples thereof include various polyurethane resins such as polyester polyurethane, polyether polyurethane, and polycarbonate polyurethane.

Among the above polyurethane resins, for example, polyester polyurethane, polyether polyurethane, etc. are obtained by the reaction of a polyhydroxy compound and a polyisocyanate. Pieces 500~
It is preferable to use a long chain diol of 5000, a short chain diol of 50 to 500, and an organic diisocyanate.

Long chain diols are broadly classified into, for example, polyester diols, polyether diols, polyether ester glycols, and the like. Specific examples of polyester diols include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, or lower alcohol esters thereof, ethylene glycol, 1.3-propylene glycol, lI4-butylene glycol, 1.
Polyester diols obtained by reacting 6-hexane glycol, diethylene glycol, neopentyl glycol, or ethylene oxide adducts to bisphenol, or mixtures thereof, or lactones obtained by ring-opening polymerization of lactones such as C-caprolactone. Examples include polyester diols and the like. Examples of polyether diol include polyethylene glycol,
Examples include polyalkylene ether glycols such as polypropylene ether glycol and polytetramethylene ether glycol, and copolymerized polyether glycols thereof. Examples of polyether ester glycols include polyester glycols obtained by reacting the above polyalkylene ether glycol as a polyol component with an aliphatic or aromatic dicarboxylic acid. If the molecular weight of this long-chain diol is too small, the urethane group concentration of the resulting polyurethane resin will be too high, resulting in poor resin flexibility and poor solubility in solvents, making it difficult to use as a binder for magnetic recording media. On the other hand, if the molecular weight of the long chain diol is too large, the long chain diol content in the resin will be too large and the urethane group concentration will be relatively small. Abrasion resistance and heat resistance decrease.

Short chain diols include, for example, ethylene glycol, propylene glycol, 1,4-butylene glycol, 1,6-
There are aliphatic glycols such as hexane glycol and neopentyl glycol, aromatic diols such as ethylene oxide or propion oxide adducts of bisphenol A, and ethylene oxide adducts of hydroquinone, and these may be used alone depending on the properties of the polyurethane resin. Alternatively, they can be mixed and used in various ratios.

Furthermore, glycerin, ethylene oxide adduct of glycerin, 2-methylpropane-1,2,3-toIJol, 4-[bis(2-hydroxyethyl))-2-hydroxypentane, 3-methylpentane-1, 3,5-triol, 1,2.6-hexane glycol,! , bis(2-hydroxyethyl)amino-2-propanol,
It is also possible to use a triol such as a propion oxide adduct of jetanolamine.

Examples of the organic diisocyanate include aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate, toluidine diisocyanate, p-phenyl diisocyanate, and 2.4-)lylene diisocyanate. , 2.6-tolylene diisocyanate, diphenylmethane diisocyanate, 3.3-dimethoxy-4,4°-diphenylene diisocyanate, 3
．． Aromatic diisocyanates such as 3'-dimethyl-4,4'-biphenylene diisocyanate, 4,4'-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, 2,4-naphthalene diisocyanate, 1.3-Diisocyanatomethylcyclohexane, 1
, 4-diisocyanatomethylcyclohexane, 4.4
Examples include alicyclic diisocyanates such as '-diisocyanate dicyclohexylmethane and inphorone diisocyanate.

On the other hand, polycarbonate polyurethane is obtained by condensing a polyol and a polyisocyanate into which a carbonate bond (carbonate bond) has been introduced.

Here, the polyol into which the carbonate bond is introduced has a molecular weight of 300 to 20,000 and a hydroxyl value of 20 to 300.
R in the general formula HO-R-OH is, for example, a polycarbonate polyol obtained by condensation of a polyhydric alcohol with phosgene, chloroacetate, dialkyl carbonate or diallyl carbonate, or alternatively, the above polycarbonate polyol and general 2〇〇C- R
Consisting of a condensation of '-COOH (R' represents -(CHl) or l-), the molecular weight is 300 to 20,000, the hydroxyl value is 5 to
300 polyester polyol. In addition, other polyols mentioned above, such as polyether polyols,
Polyester polyols, polyether ester polyols, etc. may be used in combination.

Examples of the polyisocyanate include tolylene diisocyanate, xylylene diisocyanate, toluidine diisocyanate, and any of the others mentioned above.

Note that the polyurethane resin referred to in the present invention includes polyurea resins and polyurethane urea resins in addition to the various polyurethane resins described above. The above polyurea resin and polyurethane urea resin are obtained by replacing part or all of the organic diisocyanate constituting the polyurethane resin with an organic diamine.

As a method for introducing a mercapto group into the above-mentioned polyurethane resin, any generally known method for introducing a mercapto group can be adopted, and there is no particular limitation.

For example, in the case of polyester polyurethane, a polyester having a mercapto group may be synthesized, and then the obtained polyester may be subjected to a urethanization reaction.

Here, when synthesizing polyester, isophthalic acid, terephthalic acid, adipic acid, etc. are used as acid components, while ethylene glycol, 1.4-
Butylene glycol, l.

6-hexylene glycol, neopentyl glycol, etc. are used. As part of the acid component or glycol component, for example, 3-mercapto-1.2-propanediol, 1,4-dimercapto-2,3-butanediol or thiomalic acid may be used.

In addition, in the urethanization reaction, the polyester containing a mercapto group and the polyester containing no mercapto group obtained as described above were used as the polyol component, and as the incyanate, 4゜4-diphenylmethane diisocyanate, tolylene diisocyanate, Using hexamethylene diisocyanate etc., 1.4% as a chain extender.
- Butylene glycol, neopentyl glycol, ethylene glycol, 1,6-hexylene glycol, etc. are used.

Of course, mercapto groups can be introduced into polyurethane resins other than polyester polyurethane by a similar method; for example, a polyol having a mercapto group, a dicarboxylic acid having a mercapto group, etc. may be used as part of the raw materials. .

The content of mercapto groups is preferably 0.05 to 1.0 mmoβ/g based on the polyurethane resin.
The reason is that the content of mercapto groups is 0.05 mm
oj! If it is less than 1.0 mmoffi/g, the crosslinkability will be insufficient, and if it exceeds 1.0 mmoffi/g, the solubility in solvents will decrease and the resulting coating film will have poor moisture resistance.

Further, the number average molecular weight of the polyurethane resin having a mercapto group is preferably 5,000 to toooooo.

If this molecular weight is less than 5,000, durability is insufficient, and 10
If it exceeds 0,000, solubility in solvents decreases.

In the present invention, by combining the vinyl chloride copolymer having an epoxy group and the polyurethane resin having a mercapto group, a reaction occurs between the mercapto group and the epoxy group, and the vinyl chloride copolymer and the polyurethane resin are combined. A crosslinked structure develops between the resins, resulting in a coating film with excellent durability.

The ratio of the vinyl chloride copolymer to the polyurethane resin is preferably vinyl chloride copolymer/polyurethane resin -2/8 to 8/2.

By further adding a tertiary amine compound to the binder used in the magnetic recording medium of the present invention, the ring-opening reaction of the epoxy group of the vinyl chloride copolymer can be promoted. It is also possible to form a crosslinked structure between vinyl chloride copolymers by crosslinking them with active hydrogen (for example, hydroxyl group) contained in the vinyl chloride copolymers. Of course, it is also possible to form a similar crosslinked structure with the hydroxyl groups contained in the polyurethane resin. By using the crosslinked structure between the vinyl chloride copolymer and the polyurethane resin in combination with the crosslinked structure between the vinyl chloride copolymers as described above, a magnetic coating film with even greater strength can be obtained.

Furthermore, the binder used in the magnetic recording medium of the present invention includes:
It is also possible to form a crosslinked structure by adding polyisocyanate as a curing agent and utilizing the reaction between this polyisocyanate and the hydroxyl group in the vinyl chloride copolymer or the hydroxyl group in the polyurethane resin. By using it in combination with a crosslinked structure based on mercapto groups, a magnetic coating film with even greater strength can be obtained.

The above-mentioned epoxy group-containing vinyl chloride copolymer and mercapto group-containing polyurethane resin may be used in combination with other binders.

As such other binders, those conventionally used as binders for magnetic recording media can be used, such as vinyl chloride-vinyl acetate copolymer.

vinyl chloride-vinyl acetate-vinyl alcohol copolymer,
Vinyl chloride-acetic acid and nyl-maleic acid copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, methacryl Acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer, thermoplastic polyurethane resin, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-methacrylic acid copolymer Polymers, polyvinyl butyral, cellulose derivatives, styrene-butadiene copolymers, polyester resins, phenolic resins, epoxy resins, thermosetting polyurethane resins.

Examples include 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.

A hydrophilic polar group may be introduced into the epoxy group-containing vinyl chloride copolymer or mercapto group-containing polyurethane resin or other binder used in combination for the purpose of further improving dispersibility. As a base, -5O! M group, -0505M group, PO(OM')
i group, -C00M group, -NR3X group (where M is a hydrogen atom or an alkali metal atom;

is a hydrogen atom, an alkali metal atom or a hydrocarbon atom, R
represents an alkyl group, and X represents a halogen, respectively.

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 of 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, copper, etc. metals, 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 in general 2F60°, that is, maghemite (γ-Fed, X=1.50)
,? Dannetite (F e O, x-1,33) and solid solutions thereof (F e O,, 1,33< x <1.
50). Furthermore, cobalt may be added to these ferromagnetic iron oxides for the purpose of increasing coercive force. Cobalt-containing iron oxides are roughly divided into two types: doped type and deposited type.

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

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

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

Fa-Co, Fe-N1. Fe-Co-Ni.

Co-N1. Fe-Co-B, Fe-Co-Cr-B,
Mn-Bi, Mn-Al, Fe-Co-V, etc. can be used, and Al, St, Ti, Cr, Mn, and Cu can also be used to improve various properties of these.

A metal component such as Zn may also be added.

Furthermore, in addition to the binder and ferromagnetic powder, the magnetic layer contains additives such as a dispersant, a lubricant, an abrasive, an antistatic agent,
A rust preventive agent or the like may be added. These dispersants, lubricants,
Any conventionally known abrasives, antistatic agents, and rust preventives can be used.

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 solvents, methyl acetate, ethyl acetate, butyl acetate,
Ethyl lactate.

Ester solvents such as acetic acid glycol monoethyl ether, glycol ether solvents such as glycol dimethyl ether, glycol monoethyl ether, and dioxane, aromatic hydrocarbon solvents such as benzene, toluene, and xylene, and aliphatic carbonization such as hexane and heptane. Hydrogen solvent,
Examples include organic chlorine compound solvents such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and dichlorobenzene.

Note that the above-mentioned vinyl chloride copolymer having an epoxy group and polyurethane resin having a mercapto group may be used not only for the magnetic layer but also for the back coat layer, etc. In this case, as in the case of the magnetic layer, Effects can be expected in terms of durability, etc.

[Effect]

By using an epoxy group-containing vinyl chloride copolymer and a mercapto S-containing polyurethane resin together, the epoxy group and mercapto group bond together during curing, creating a cross-linked structure between the vinyl chloride copolymer and the polyurethane resin. is expressed.

The crosslinking reaction due to the action of the epoxy group and mercapto group described above proceeds almost unaffected by moisture. Therefore, a good crosslinked structure is formed, and when formed into a coating film, it exhibits excellent durability.

〔Example〕

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

First, a polyurethane resin and a vinyl chloride copolymer as a binder were synthesized.

Polyurethane resin is polybutane adipate-MDI
The average molecular weight was 20,000 to 24,000. The amount of mercapto group introduced is 0 and 1 m, respectively.
mol/g (sample name PU-1), 0.2 mmol
/g (sample name PU-2), 0.3m amount o1/g (
Sample name PU-3), Os+ mol/g (Sample name P
U-4).

The vinyl chloride copolymer is a vinyl chloride-glycidyl methacrylate copolymer, and has an average degree of polymerization of 310 to 350.
And so. Note that the vinyl chloride copolymer has 0.1 OaNa group as a polar group. ．． 08 mmol/g was introduced. In addition, the amount of introduced epoxy groups is 0.6, respectively.
a+ mol/g (Sample name VC-IL1.Om m
ol/g (sample name VC-2), Os mol/g
(Sample name VC-3).

A magnetic recording medium was produced using the synthesized polyurethane resin and vinyl chloride copolymer by the following method.

Co-adhered y-Fe, Os 100 parts by weight (specific surface area 40nf/g) Polyurethane resin 12 parts by weight Vinyl chloride copolymer 12 parts by weight Carbon black (antistatic agent) 2 parts by weight Albah (abrasive) 5 parts by weight dimethyl silicone (lubricant) 0.5 parts by weight butyl stearate (lubricant) 1 part by weight dimethyl myristylamine
1.5 parts by weight methyl ethyl ketone
100 parts by weight toluene
60 parts by weight cyclohexanone
60 parts by weight The above composition was mixed in a ball mill for 24 hours, filtered through a 3 μm filter, and then coated on a 14 μm thick polyethylene terephthalate film so that the film thickness after drying was 6 μm. After performing the orientation treatment, it was dried and rolled up.

After further supercalendering, an additional 75
A sample tape was prepared by heat-treating at ℃ for 24 hours and cutting into 1/2 inch width.

Table 1 shows the polyurethane resin and vinyl chloride copolymer used in each sample tape produced (Examples 1 to 4, Comparative Examples 1 to 3).

Table 1 For each of the sample tapes obtained, still characteristics and drop-off were measured.

The above still characteristics are based on a sample tape with a frequency of 4.2MHz.
The video signal was recorded, and the time until the playback output attenuated to 50% was taken as the time. 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). Second result
Shown in the table.

Table 2 As is clear from the above Table 2, it can be seen that the sample tapes according to the present invention not only had less powder falling off, but also had significantly improved still characteristics.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
Since we use a vinyl chloride copolymer containing epoxy groups and a polyurethane resin containing mercapto groups,
A crosslinked structure develops between the vinyl chloride copolymer and the polyurethane resin, forming a coating film with excellent mechanical strength.

In addition, since this reaction proceeds almost unaffected by moisture, the crosslinked structure is reliably achieved and a magnetic coating film with very good durability can be obtained.

Therefore, by using this binder, a magnetic recording medium with excellent durability can be provided without deteriorating the electromagnetic conversion characteristics.

Patent Applicant Sony Corporation Agent Patent Attorney Akira Kowa (2 others) Tsukasa 1Jv and (Ichimasho (spontaneous) June 120, 1999 Commissioner of the Japan Patent Office Yoshi 1) Takeshi Moon Hit 1, Incident Display 1986 Year Patent 1 No. 149957 2, Name of the invention Magnetic recording medium 3, Relationship to the case of person who makes a 1li correction Patent applicant address 6-7-35, Kitashina, Tokyo Parts Ward Name (21
8) Sony Corporation Representative Norio Ohga 4, Agent address 11, 2-6-4 Toranomon, Minato-ku, Tokyo 105
Mori Building 11th floor (50B) 826G &su 6, "Detailed explanation of the invention" column 7 of the specification subject to amendment, Contents of amendment (1) Statement on page 13, line 12 of the specification Above description

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 binder is a vinyl chloride copolymer having an epoxy group. , a magnetic recording medium comprising a polyurethane resin having a mercapto group.