JPH01194127A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve electromagnetic conversion characteristics and durability by bonding magnetic powder and a binder having a basic polar group via aminocarboxylic acid. CONSTITUTION:A resin having a basic polar group in the molecule is incorporated into the binder of the magnetic recording medium having a magnetic layer 2 essentially consisting of the magnetic powder and binder on a nonmagnetic base 1 and the aminocarboxylic acid is incorporated into the magnetic layer 2. The aminocarboxylic acid, therefore, intervenes between the binder and the magnetic powder to well bond both and since the surface of the magnetic powder is covered by proton-donating acid groups, the adsorption of various additives including a lubricant having oxygen-domating atomic groups, dispersant, etc., is hindered. The coated film is thereby perfected without losing the dispersion stability of the magnetic powder and the boundary face reinforcing property of the binder. The coated film having the high magnetic characteristics, high surface luster and high strength is thus formed and the magnetic recording medium which is excellent in the electromagnetic conversion characteristics and the durability of the coated film 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 in particular to a dispersion of magnetic powder mixed in a magnetic layer formed on a non-magnetic support. It concerns sexual improvement.

[Summary of the invention]

The present invention uses a resin having a basic polar group in the molecule as the binder of the magnetic layer constituting the magnetic recording medium, and further contains an aminocarboxylic acid in the magnetic layer, so that the lubricant is adsorbed to the magnetic powder. In addition to preventing this, the aim is to improve the dispersibility of the magnetic powder and reduce its falling off, thereby improving the deterioration of the electromagnetic conversion characteristics and improving the durability of the magnetic coating film.

[Conventional technology]

Magnetic recording media are moving toward higher density recording year by year. Under these circumstances, in the magnetic layer, magnetic powder with an extremely fine particle size is highly dispersed in the binder resin, making the surface of the magnetic layer mirror-finished, improving the electromagnetic conversion characteristics, and at the same time improving the magnetic properties. There is a need to improve the durability of paint films.

That is, in the above magnetic recording medium, how well the magnetic powder contained in the magnetic layer is dispersed in the paint;
How to bond well with the binder is a very important issue.

Conventionally, as a method to satisfy the above requirements, a so-called dispersant (for example, a surfactant) is added to the magnetic paint to bond the hydrophilic groups of the surfactant with the hydrophilic groups of the magnetic powder, and then It has been proposed to bond the magnetic powder and the binder by bonding the lipophilic group of the activator and the lipophilic group in the binder to improve durability and dispersibility of the magnetic powder. There is. However, in this method, since the lipophilic group of the dispersant has no polarity, the bonding force with the binder is very weak, and the interface reinforcing function is not fully exhibited.

Additionally, if an excessive amount of dispersant is added in order to exert its interface reinforcing function, the binder may become plasticized or the dispersant may precipitate on the surface of the coating film, resulting in a significant lack of durability of the coating film. There is.

In response to this, in recent years, a method of introducing a polar group into a binder has been proposed, and a technique has been proposed in which the binder has both the functions of a polymer, a dispersant, and an interface reinforcing agent. However, as mentioned above, when trying to introduce polar groups into the binder and thereby reinforcing the interface with the magnetic powder, the steric structure between the parent groups of the polar groups is caused by the function of the binder as a polymer. Due to obstacles, the magnetic layer cannot be sufficiently adsorbed with the hydrophilic groups on the surface of the magnetic layer, resulting in deterioration of dispersibility.Also, there are compounds with long-chain alkyl groups, fatty acids, etc. added to the paint for the purpose of improving durability. In this case, these particles are preferentially adsorbed to the magnetic powder, which hinders the adsorption of the binder having a dispersion function, resulting in problems such as deterioration of the dispersibility of the magnetic powder.

[Problem to be solved by the invention]

As mentioned above, in the field of magnetic recording media, there are still dissatisfaction with various practical characteristics due to the binder used, the ability of the polar group added to it, the relationship between the polar group and the magnetic powder, etc. There is.

Therefore, the present invention was proposed in view of the above-mentioned conventional situation, and aims to prevent the adsorption of lubricant to magnetic powder, improve the dispersibility of magnetic powder, reduce falling off, and improve electromagnetic conversion. The purpose is to provide a magnetic recording medium with excellent characteristics and durability.

[Means to solve the problem]

As a result of intensive research, the inventors of the present invention have determined that the above object can be achieved by bonding the magnetic powder and a binder having a basic polar group through an aminocarboxylic acid, instead of allowing the magnetic powder to interact with the binder having a basic polar group. The affinity with the binder is significantly improved,
We have come to the knowledge that magnetic powder can be dramatically improved.

The present invention has been made based on the above findings, and as shown in FIG. In the recording medium, the binder is a resin having a basic polar group in its molecule, and the magnetic layer (2) contains an aminocarboxylic acid.

The present invention also provides a non-magnetic support (1
1) may be applied to a magnetic recording medium having a magnetic layer (12) on one surface and a back coat layer (13) mainly composed of non-magnetic powder and a binder on the other surface.

Here, the resin having a basic polar group constituting the magnetic layer paint of the above-mentioned magnetic recording medium is a resin that is usually used as a binder for this type of magnetic recording medium, and is a resin having a basic polar group as shown below. Any device that has been introduced can be used.

Furthermore, for example, a resin into which a basic polar group has been introduced may be used alone, a resin into which a basic polar group has been introduced and a resin without a polar group, or a resin into which a basic polar group has been introduced may be used. Any combination of different resins can be used.

In addition, when combining a resin into which a basic polar group has been introduced and a resin into which no polar group has been introduced, it is necessary that the resin into which a basic polar group has been introduced is combined at a ratio of at least 10% or more. be.

Examples of such resins include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-vinylidene chloride copolymer, and vinyl chloride. −
Acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, methacrylic ester-vinylidene chloride copolymer, methacrylic ester-styrene copolymer, thermoplastic polyurethane resin, Polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, polyvinyl butyral, cellulose derivative.

Examples include binder resins such as styrene-butadiene copolymers, polyester resins, phenolic resins, epoxy resins, thermosetting polyurethane resins, urea resins, melamine resins, alkyd resins, urea-formaldehyde resins, or mixtures thereof.

The basic polar groups introduced into these resins include (b)
Examples include primary amines (-NHK), secondary amines (:NH), and tertiary amines (:N) that are introduced in the form of -NHCHZCHz-, etc., and those that are introduced in the form of quaternary ammonium salts. There may be.

Alternatively, it may be introduced in the form of a heterocycle such as the following.

Furthermore, it may be introduced in the form of C, -N-) to the Schiff base shown in the following, or it may be introduced in the form of a diazo group (-N=N-). .

Any conventionally known method can be used to introduce the above-mentioned basic polar group. For example, a typical basic polar group such as tertiary amine or quaternary ammonium may be introduced into a condensation resin (for example, polyurethane). In order to introduce, (i) a method using a basic polar group-containing polyol, polyisocyanate, etc. as part of the chain extender, (ii) active hydrogen etc. (e.g. hydroxyl group) remaining in the side chain or terminal of the condensation resin. For example, a method may be used in which a compound is modified using a compound having both a group capable of reacting with active hydrogen and a basic polar group in the molecule.

In addition, in order to introduce these polar groups into a copolymer resin such as vinyl chloride resin, (iii) both a vinyl monomer such as vinyl chloride and a basic polar group having a copolymerizable double bond are added to the molecule. (iv) A method of introducing active hydrogen in advance and modifying it with a compound having both a group capable of reacting with active hydrogen and a basic polar group in the molecule, etc. It's fine.

In addition, the content of basic polar groups contained in the binder is O,OOl m mol/g to 1.0 m mol
It is preferably within the range of /g.

Examples of the magnetic powder dispersed in the binder to form the magnetic layer include ferromagnetic iron oxide particles, ferromagnetic chromium dioxide, ferromagnetic alloy powder, hexagonal barium ferrite i particles, iron nitride, and the like.

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

X=1.50),? Dannetite (FeJn, 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 oxide: 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 'l'e, Sb, Fe, Ti, V, Mn, etc. can be used.

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

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

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

Mn-B1. Mn-Aj! , Fe-Co-V, etc. can be used, and AR, S
Metal components such as t, Ti, Cr, Mn, Cu, and Zn may be added.

In the magnetic recording medium of the present invention, the magnetic layer may be formed, for example, by dispersing the above-mentioned ferromagnetic powder in the above-mentioned binder and dissolving it in an organic solvent, and applying a magnetic paint to the surface of the non-magnetic support. Bye.

Examples of organic solvents used in coating and forming the magnetic layer include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, methyl acetate,
Ethyl acetate, butyl acetate.

Ester types such as ethyl lactate and glycol monoethyl acetate, glycol dimethyl ether.

Glycol ethers such as glycol monoethyl ether and dioxane, aromatic hydrocarbons such as benzene, toluene, and xylene, aliphatic hydrocarbons such as hexane and heptane, methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, and ethylene chlorohydrin. , chlorinated hydrocarbons such as dichlorohenzene, and the like.

In the present invention, the above-mentioned binder having a basic polar group is interposed between the binder and the magnetic powder to increase the affinity between the binder and the magnetic powder and improve the dispersibility of the magnetic powder in the binder. In addition, aminocarboxylic acid is blended into the magnetic layer as an additive to strengthen the bond between the binder and the magnetic powder. The above-mentioned aminocarboxylic acid is a compound each having one or more COOH, which is a group having a salt-forming ability, and one or more amine groups, which has a coordinating ability, in its molecule. Specific examples of the above aminocarboxylic acids include iminodiacetic acid (IOA), ethylenediaminetetraacetic acid (HD, TA), nitrilotriacetic acid (NT
A), uramyl diacetic acid (ODA), diethylenetriaminepentaacetic acid (DTPA), ethylene glycol bis(
2-aminoethyl)etherdiaminetetraacetic acid (GEDTA)
), triethylenetetraminehexaacetic acid (TTHA), L
2-cyclohexanediamine-N,N'-tetraacetic acid (CYD
TA), β-aminoethylsulfonic acid-N, N'-diacetic acid, β-aminoethylphosphonic acid-N, N'-diacetic acid, etc., as well as aliphatic aminocarboxylic acids such as glycine, alanine, valine, leucine, Isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, lysine, arginine, phenylalanine as an aminocarboxylic acid with an aromatic nucleus, 1,000 rosine, histidine, tryptophan, proline, oxy as an aminocarboxylic acid with a heterocyclic ring Examples include proline, and further examples include β-aminopropionic acid, γ-aminobutyric acid, anthranilic acid, tsuru-aminobenzoic acid, p-aminobenzoic acid, and the like.

If the aminocarboxylic acid mentioned above has too large a nonpolar moiety such as an alkyl group, the bonding force with the binder will decrease, and the aminocarboxylic acid itself functions as a dispersant or a lubricant. Since it is not, the number of carbon atoms is 9
It is preferable that it is below. However, this is not the case especially in the case of heterocyclic aminocarboxylic acids.

The above aminocarboxylic acid can be interposed between the magnetic powder and the binder by adding it when preparing the magnetic paint, by pre-surface treating the magnetic powder with aminocarboxylic acid, and by forming a magnetic layer. There is a method of applying aminocarboxylic acid from the upper back. The amount of the aminocarboxylic acid added is 0.00 parts by weight per 100 parts by weight of the magnetic powder.
It is preferably within the range of 0.05 to 5 parts by weight (expressed as 0.05 to 5 PHP. The same applies hereinafter), and 0.3 to 3 PHP.
More preferably, it is within the range of HP. If the amount of aminocarboxylic acid added is less than this range, the effect of adding aminocarboxylic acid cannot be expected, and if the amount of aminocarboxylic acid added is more than this range, the coating film will shift to the acidic side and the coating will be difficult. This will lead to deterioration of the corrosion resistance of the film.

In addition to the above-mentioned binder and magnetic powder, the above-mentioned magnetic layer contains a dispersant, a lubricant, an abrasive, an antistatic agent, and an anti-rust agent, which are usually used as additives constituting the magnetic layer of a magnetic recording medium. When adding these substances, it is preferable to add them within a range that does not inhibit the effect of adding the aminocarboxylic acid.

In particular, as the fatty acid used for the purpose of imparting lubricity to the magnetic layer and improving the durability of the magnetic layer, a fatty acid having a carbon number of 10 or more is usually used. The fatty acid may be any fatty acid that is normally used in this type of magnetic recording medium, and includes saturated fatty acids, unsaturated fatty acids, and the like. Specifically, the above fatty acids include capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, valmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, and cerotic acid. , heptaconic acid, montanic acid, mellisic acid, lafcelic acid, undecyl acid, oleic acid, elaidic acid, cetoleic acid, erucic acid, brassic acid, linoleic acid, linoleic acid, arachidonic acid, stearolic acid, and the like.

These fatty acids have a non-polar alkyl group in their structure, so they have a weak bonding force with the binder. However, if the surface of the magnetic powder is basic, the fatty acids preferentially bind to the binder. It is adsorbed and significantly deteriorates the durability of the paint film. However, in the magnetic recording medium of the present invention, since aminocarboxylic acid is added to the magnetic layer, this aminocarboxylic acid is preferentially adsorbed to the surface of the magnetic powder having basic active sites, and the magnetic powder The surface of the soil appears to be an acidic point. Therefore, fatty acids and the like are adsorbed, and the magnetic powder is bonded well to the binder, improving the dispersibility of the magnetic powder. Furthermore, since the fatty acid exists alone in the magnetic layer, it can exhibit a good lubricating effect.

The material for the nonmagnetic support forming the magnetic layer as described above may be any material that is normally used in this type of magnetic recording medium, such as polyesters such as polyethylene terephthalate, polyethylene, etc. , polyolefins such as polypropylene, cellulose inducers such as cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, and polyvinyl chloride.

Examples include vinyl resins such as polyvinylidene chloride, plastics such as polycarbonate, polyimide, polyamide, and polyamideimide, paper, metals such as aluminum and copper, light alloys such as aluminum alloys and titanium alloys, ceramics, and single crystal silicon. The forms of this non-magnetic support include film, tape, sheet disk, card,
Any drum or the like may be used.

[Effect]

The aminocarboxylic acid used in the present invention is characterized in that at least one group having a salt-forming ability (between proton-donating acidic groups) or a group having a coordination ability contained in the molecule is attached to a basic active site on the surface of the magnetic powder. , bonds with acidic active sites, etc., and the other group with salt-forming ability (between proton-donating acidic groups) forms a coordinate bond with the basic polar group (especially proton-accepting nitrogen) of the binder resin. It has a remarkable effect on the dispersibility of magnetic powder in the agent and the reinforcement of the interface.

In addition, by adsorbing aminocarboxylic acids to the basic active sites or acidic active sites on the surface of the magnetic powder, the surface of the magnetic powder is covered between proton-donating acidic groups, so oxygen-donating atoms such as fatty acids As a result, the coating film is completed without losing dispersion stability or interfacial reinforcement, and has high magnetic properties, high surface gloss, and durability. A coating film with excellent properties is completed.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples.

First, Examples using various aminocarboxylic acids will be shown.

Oketsukai CO adhesion r FezO 312 parts by weight (basic pl+ 9.0. Surface area 30 m2/g) Binder (polyurethane resin containing tertiary amine group 0.30 m mol/g 3 parts by weight) Solvent (methyl ethyl ketone) 26. 7 parts by weight 2 PHP of ethylenediaminetetraacetic acid (EDTA), which is an aminocarboxylic acid, is added to the magnetic paint having the above composition, mixed in a ball mill for 24 hours, taken out through a filter, and the magnetic paint is coated with a 12 μm thick polyethylene terephthalate film. It was coated on top so that the thickness after drying would be 5 μm, and after magnetic field orientation, it was wound up. This was calendered and cut into 1/2 inch width to produce sample tapes.

2-17 Sample tapes were prepared in the same manner as in Example 1 except that the type of aminocarboxylic acid and the amount added were changed as shown in Table 1.

A sample tape was prepared in the same manner as in Example 1 except that the basic composition shown in Example 1 above was used as a basic composition in which no aminocarboxylic acid was added.

For each sample tape produced as described above, gloss, powder removal, magnetic flux density Bm, squareness ratio Rs, coercive force H
c was measured. The above gloss was measured at an incident angle of 75 using a gloss meter.
The reflectance at a reflection angle of 75° was measured. In addition, for powder falling, visually observe the amount of powder falling into the head drum guide bin etc. after running the shuttle 100 times for 60 minutes, and score 0 if there is almost no powder falling, and 1 score if there is a very large amount of falling powder. It was evaluated as 5 points.

Furthermore, the magnetic properties were measured in a magnetic field of 2500 Gauss. The results are shown in Tables 2 and 3.

Table 2 Table 3 As is clear from Tables 2 and 3 above, by adding aminocarboxylic acid to the magnetic layer, there is very little powder falling off, which improves the durability of the magnetic recording medium. With,
The magnetic properties and gloss become good, and the electromagnetic conversion properties of the magnetic recording medium are improved.

Nitrilotriacetic acid (
NTA), uramyldiacetic acid (ODA), iminodiacetic acid (IDA), ethylenediaminetetraacetic acid (EDTA),
1.2-Cyclohexanediamine-N.

Examples include N-triacetic acid IG (CYDTA) and aspartic acid.

Next, an example was conducted to examine the effects of adding fatty acids to magnetic paint.

Co-adhered r-Fe, 03 12 parts by weight (surface basic pH 9.0, surface area 30%/g) Binder (polyurethane resin containing tertiary amine group 0.30 steel mol/g 3 parts by weight) ) 26.7 parts by weight of solvent (methyl ethyl ketone) 2 PHP of nitrilotriacetic acid, which is an aminocarboxylic acid, and 0.25 PHP of myristic acid, which is a fatty acid, were added to the magnetic paint having the above composition.
After mixing for 4 hours, it was taken out through a filter, and the magnetic paint was applied onto a 12 μm thick polyethylene terephthalate film so that the thickness after drying was 5 μm.
After magnetic field orientation, it was wound up. This was calendered and cut into 1/2 inch width to produce sample tapes.

Sample tape was prepared in the same manner as in Example 1 except that the amount of fatty acid added was changed as shown in Table 4.

References 1 to 12 Sample tapes were prepared in the same manner as in Example 1 except that the amount of fatty acid added was changed as shown in Table 4.

Six! 2 to 617 A sample tape was prepared using the same method as in Example 1, except that the basic composition shown in Example 1 was not added with aminocarboxylic acid and the amount of fatty acid added was changed as shown in Table 4. was created.

Table 4 Gloss, powder removal, magnetic flux density Bm, squareness ratio Rs, coercive force H for each sample tape produced as described above
c, blooming, and magnetic permeability μ were measured.

The above gloss uses a glossy needle with an incident angle of 75° and a reflection angle of 75°.
The reflectance at 100°C was measured. In addition, for powder falling off, visually observe the amount of falling powder on the head drum, guide pins, etc. after running the shuttle 100 times for 60 minutes. It was evaluated as 15 points. Furthermore, the magnetic properties were measured in a magnetic field of 2500 Gauss.

The results are shown in Table 5.

(Left below) As is clear from Table 5 above, the amount of powder falling off of the magnetic recording medium increases in proportion to the amount of fatty acid added in the system in which aminocarboxylic acid is not added. In the added system, the amount of powder falling off is not affected by the amount of fatty acid added.

Furthermore, since adsorption of fatty acids to the magnetic powder is suppressed, plumping occurs when a large amount of fatty acids is added. Therefore, when an aminocarboxylic acid is added, a large effect can be expected with a very small amount of fatty acid.

Furthermore, the influence of the addition of aminocarboxylic acid on the type of magnetic powder and the type of polar group added to the binder was investigated.

Cold spot 1 degree metal powder (52m”/g, pH 9.5)
12 parts by weight Binder (Molecular weight 35,000, urethane resin containing 0.3 mn+ol/g of tertiary amine) 3 parts by weight Solvent (26.7 parts by weight Methyl Ethyl Ketone 'I) 2 PHP of certain nitrilotriacetic acid was added, mixed in a ball mill for 24 hours, taken out through a filter, and this magnetic paint was applied onto a 12 μm thick polyethylene terephthalate film so that the thickness after drying was 5 μm, and magnetic field orientation was applied. The tape was then rolled up. After calendering, it was cut into 1/2 inch width to produce a sample tape.

The magnetic powder and binder used in Example 20 were
A sample tape was prepared in the same manner as in Example 20, except for the changes shown in the table.

11-Fly, 18-113 A sample tape was prepared in the same manner as in Example 20, except that the types and amounts of the magnetic powder, binder, and aminocarboxylic acid used in Example 20 were changed as shown in Table 6. Created.

Table 6 Note that all binders in Table 6 above have a molecule of ff13500.
It is 0.

For each sample tape produced as described above, gloss, powder removal, magnetic flux density Bm, squareness ratio R3% coercive force H
e was measured. The above gloss uses a glossy needle with an angle of reflection of 7.
The reflectance was measured at an angle of 5° and an incident reflection angle of 45°. In addition, for powder falling, visually observe the amount of powder falling on the head drum, guide pin, etc. after running the shuttle 100 times for 60 minutes, and score 0 if there is almost no powder falling, and score 0 if there is a very large amount of falling powder. It was evaluated as 15 points. Furthermore, the magnetic properties are 25
This was measured in a magnetic field of 0.00 Gauss. The results are shown in Table 7. Note that for barium ferrite, the results are for simultaneous alignment in the longitudinal direction.

Table 7 As is clear from Table 7, the effect of adding aminocarboxylic acid to the magnetic layer is greatest when the metal powder has a basic surface and the binder contains a tertiary amine. Ta.

In addition, in any case, by adding aminocarboxylic acid, powder dropout is reduced, the durability of the magnetic recording medium is improved, and magnetic properties and gloss are improved, improving the electromagnetic conversion characteristics of the magnetic recording medium. .

[Effects of the Invention] As is clear from the above explanation, since aminocarboxylic acids are added to the magnetic layer in the present invention and related magnetic recording media, the aminocarboxylic acids are present between the binder and the magnetic powder. The surface of the magnetic powder is covered with proton-donating acidic groups, which prevents the adsorption of various additives such as lubricants and dispersants having oxygen-donating atomic groups.

As a result, the dispersion stability of magnetic powder and the field of binder.

A coating film is completed without losing surface reinforcing properties, and a coating film with high magnetic properties, high surface gloss, and strong strength is formed.

Therefore, by using this as a magnetic layer of a magnetic recording medium, a magnetic recording medium with excellent electromagnetic conversion characteristics and coating film durability can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a magnetic recording medium to which the present invention is applied. FIG. 2 is a schematic cross-sectional view showing another example of the configuration of a magnetic recording medium to which the present invention is applied. 1.11...Non-magnetic support 2.12...Magnetic layer 13...Back coat layer Patent applicant: Sony Corporation Representative Patent attorney: Kodo Kosho Yuzai Sakae - Masaru Sato Figure 2 Procedures Dispute official document (spontaneous) June 77, 1988 Patent application No. 18748 Relationship with car case Patent applicant address Tokyo Parts Illustrated Product 6th Roar No. 35 Name (2
18) Sony Co., Ltd. Representative Nori Ohga voluntarily 6. Subject of amendment 7. Contents of the amendment The scope of the patent claims will be amended as shown in the attached sheet. From line 20 on page 1 to line 1 on page 2 of the specification, the statement ``The binder for the magnetic layer is a resin having a basic polar group in its molecule'' has been replaced with ``the binder for the magnetic layer is a resin having a basic polar group in its molecule.'' Contains a resin having a basic polar group in the molecule.'' In the 20th line of page 1 of the specification, the statement "is a resin having a basic polar group" is amended to "includes a resin having a basic polar group." From line 7 to line 8 of page 6 of the specification, the statement ``combinations of resins, etc.'' has been changed to ``combinations of resins, combinations of resins with basic polar groups introduced with other polar groups, etc.'' combination of resins, etc.,” is corrected. From line 9 to line 10 of page 6 of the specification, the statement ``[In the combination of a resin into which a basic polar group has been introduced and a resin in which no polar group has been incorporated],'' has been changed to ``basic.'' The resin into which a polar group has been introduced is corrected as ". On page 7, line 12 of the specification, “as a basic polar group,”
Add "for example" after a certain statement. [Alternatively, add "for example" after the statement "J" on the 5th line of No. 8 of the specification. On page 9, line 8 of the specification, after the statement ``It may be one that has been introduced.'', ``In other words, it may be one that has a chino atom having an unpaired electron as a polar group.''
join. The description “CrO” on page 11, line 12 of the specification is
Correct with crozz. (7-10> On page 14, line 16 of the specification: [Magnetic powder and binder-
1 is corrected to ``magnetic powder (gold member) and binder''. On page 14, line 18 of the specification, the statement ``Additionally, magnetic powder is added in advance'' is amended to ``Also, magnetic powder (gold member) is added in advance.'' From page 14, line 19 to page 15, line 1 of the specification, the statement ``There is a method of surface treatment, and a method of coating an aminocarboxylic acid from the top after forming a magnetic layer.'' has been changed to ``surface treatment.'' There is a way to deal with it.'' From line 16 to line 17 of page 16 of the specification, the statement "preferentially when matched in basicity" has been amended to "particularly preferentially when matched in basicity" do. On page 17 of the specification, from line 17 to line 18, the statement ``plastics such as polyamideimide'' has been amended to ``plastics such as polyamideimide, polyphenylene sulfide, etc.''. In Table 4 on page 26 of the specification, the statement "magnetic permeability μ" in the third column at the top is corrected to "friction coefficient μ." Table 5 on page 28 of the specification is amended as follows. (The following is a blank space) Attached Patent Claims ``A magnetic recording medium having a magnetic layer mainly composed of magnetic powder and a binder on a non-magnetic support, wherein the binder comprises a resin having a basic polar group in its molecules. a magnetic recording medium characterized by containing an aminocarboxylic acid in the magnetic layer.''

Claims (1)

[Claims] In a magnetic recording medium having a magnetic layer mainly composed of magnetic powder and a binder on a non-magnetic support, the binder is a resin having a basic polar group in the molecule, and an aminocarboxylic acid is contained in the magnetic layer. A magnetic recording medium characterized by containing.