JPS5924439A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having good abrasion resistance and S/N ratio, by contg. a polymer which has at least one or more monomer units having a negative org. group as a component of the copolymer and in which the org. group forms a salt. CONSTITUTION:The negative org. group is preferably a carboxyl group and a residual phosphoric acid group, and the salt is preferably an ammonium salt and an amine salt. An acrylic acid and maleic anhydride are preferrable as the monomer unit because of their particularly outstanding storage stability and dispersibility. The weight average mol.wt. (Mw) of the polymer is used 1,000- 500,000 and preferably 1,000-50,000 range is used. The polymer is used usually at 0.5-15pts.wt. , more preferably 0.5-10pts.wt. range based on 100pts.wt. magnetic powder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to magnetic recording media such as magnetic tapes and magnetic sheets, and particularly to high-density magnetic recording media that have good surface properties, wear resistance, storage stability, and high playback performance. It is something.

Conventionally, in magnetic recording media such as audio tapes and video tapes, magnetic powder is coated on film supports such as polyethylene terephthalate, cellulose triacetate, polycarbonate, borizlobyrene, and polyvinyl chloride. vinyl-cyclized vinylidene copolymer, polybutyl acrylate, butyl acrylate-ac I
JE-Nitrile copolymer, cellulose resin, epoxy resin, polyvinyl butyral resin, polyurethane resin, and other binders were kneaded and coated.

However, the use of these binders alone or in combination tends to result in poor dispersibility of the magnetic powder, and as a result, the surface properties and wear resistance of conventional magnetic recording media are not fully satisfied. Ta.

Especially for video tapes that require short wavelength recording,
Poor dispersion of magnetic powder in the magnetic recording layer leads to a deterioration of the S/N ratio and a decrease in sensitivity, and since such a recording medium comes into intense sliding contact with the magnetic head during recording and reproduction, the magnetic coating is worn out by repeated use. The magnetic powder contained in the coating film is likely to fall off, resulting in undesirable results such as clogging of the magnetic head.

For this reason, various additives are used for the purpose of improving the dispersibility of magnetic powder and improving the wear resistance. For example, Special Publications No. 41-18064, No. 43-186, No. 43
-669, 47-15624°, 50-401
No. 03, JP-A-49-53402, JP-A No. 49-5880
No. 4, No. 49-84405, No. 51-40904,
As described in each publication of No. 52-70811, a magnetic paint containing magnetic powder and a binder contains higher fatty acids, fatty acid amides, fatty acid esters, higher alcohols, metal soaps, sulfuric esters of higher alcohols, and HoIJ. - Magnetic recording media are produced by coating a support with a magnetic coating containing ethylene oxide, lecithin, etc.

However, even with the addition of these additives, it has been difficult to obtain a magnetic recording medium with desirable characteristics.

For example, the use of large amounts of these additives has the undesirable effect of reducing the mechanical strength of the magnetic recording layer. In addition, after the magnetic recording layer is formed, a so-called pluming phenomenon occurs in which the additive gradually oozes out, resulting in undesirable results in terms of storage stability. Furthermore, the magnetic properties of the magnetic recording layer and the dispersibility of the magnetic powder were never satisfactory.

Furthermore, JP-A-57-44225 proposes a method using a polymer having polar functional groups such as a carboxyl group, a hydroxyl group, a phenolic -011i group, a sulfonic acid group, etc. Although it is more effective in suppressing the pluming phenomenon than the known fractional agents, it is still unsatisfactory in terms of dispersibility.

An object of the present invention is to provide a novel magnetic recording medium that overcomes the above-mentioned drawbacks.

Another object of the present invention is to provide a magnetic recording medium with good wear resistance.

Still another object of the present invention is to provide a magnetic recording medium with a good S/N ratio.

Still another object of the present invention is to provide a magnetic recording medium with high reproduction output.

Still another object of the present invention is to provide a magnetic recording medium with good storage stability.

However, as a result of intensive studies in order to achieve the above-mentioned object, the present inventors found that the copolymerization component has at least one monomer unit having a negative organic group, and the organic group forms a salt. However, it has been found that this can be achieved by a magnetic recording medium characterized by containing a polymer compound.

In the monomer unit VC having a negative organic group as a component of the copolymerization of the polymer compound according to the present invention (hereinafter referred to as monomer unit A of the present invention), the negative organic group is, for example, a carboxyl group, a phosphoric acid residue. and sulfonic acid residues, among which carboxyl groups and phosphoric acid residues are preferred, and their salts include ammonium salts, amine salts, alkali metal salts, etc., with ammonium salts and amine salts being preferred. Examples of the monomer Uniiso)A of the present invention include acrylic acid, methacrylic acid, maleic anhydride 12-
Hydroxyethyl acryloyl phosphate, etc.
Among these, acrylic acid and maleic anhydride are preferred.

The negative organic group is preferably a carboxyl group or a phosphoric acid residue, the salt is preferably an ammonium salt or an amine salt, and the monomer unit A is preferably acrylic acid or maleic anhydride because of its storage stability and dispersibility. This is because it is particularly excellent. Vr: To improve the pluming phenomenon, etc., conventionally used additives have poor storage stability, tend to stick together, and tend to cause pressure agglomeration during dispersion at the cost of improving the pluming phenomenon. However, the polymer compound according to the present invention was excellent in these points.

In addition, monomer units other than monomer unit A (hereinafter referred to as mono V-, IL-nia of the present invention) of the polymer compound according to the present invention include, for example, styrene, 〇-methylstyrene,
m-methylstyrene, p-methylstyrene, p=ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-t@rt-butylstyrene, p-n-
hegylstyrene, p n-t butylstyrene, p
n-nonylstyrene, p n-decylstyrene, p-n
Examples include styrene and styrene derivatives such as -dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene. Examples of other vinyl monomers include ethylene,
Vinyl halides such as propylene, butylene, vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride: vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate... Vinyl esters of nylnato, methyl diacrylate, acrylic Ethyl acid, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-quinylethyl acrylate, phenyl acrylate, α-chlor methyl acrylate,
Methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylic alIn-butyl 1 isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, α-methylene aliphatic monocarboxylic acid esters such as phenyl methacrylate, dimethylaminoethyl methacrylate, dimethyl methacrylate 7-minoethyl: acrylonitrile, methacrylonitrile) Acrylic acid or methacrylic acid derivatives such as acrylamide: vinyl methyl ether , vinyl ethyl ether, vinyl isobutyl ether natonovinyl ethers: vinyl ketones such as vinyl methyl natone, vinyl hexyl ketone, methyl isopropenyl ketone: N-vinylpyrrole, N-vinyl carba-
Examples of the polymer compound according to the present invention are listed below.

Exemplary compound (a) Ammonium salt of a copolymer of acrylic acid/butyl 7-crylate) = 8/2 (b) Acrylic acid/N-octylacryl 7-mide = 7
Ammonium salt of copolymer of /3 (c) Maleic anhydride #/-propylene ==: 1/1
Sodium salt of a copolymer of (d) Ammonium salt of a copolymer of maleic anhydride/styrene = 1/1 (e) Methacrylic acid/methyl methacrylate =
Octylamine salt of copolymer of 377 (f) 2-Hydroxyethyl 7-kryloylphosph?
Ammonium salt of a copolymer of ethyl ethyl ester/lauryl 7cryl) = 3/7 Weight average molecule ffi (Mw) of the polymer compound of the present invention
is used in the range of 1,000 to 500,000, preferably in the range of 1,000 to 50,000.

In order to incorporate the polymer compound according to the present invention into the magnetic powder, at least one kind of the polymer compound according to the present invention is dissolved in a solvent such as toluene, methyl ethyl ketone, ethyl cellosolve, 7 setone, methanol, etc. After dipping the magnetic powder in a predetermined ratio and stirring and mixing, the mixture is filtered or evaporated and then subjected to a drying process, or at least one of the polymer compounds according to the present invention is dissolved directly or in an appropriate solvent at the time of dispersing the magnetic powder. [May be added.]

The polymer compound according to the present invention usually has a magnetic powder of 100 weight fi.
It is desirable that the amount used is from 0.5 parts by weight to 15 parts by weight, preferably 0.5 parts by weight per part by weight.

If the polymer compound according to the present invention is less than 0.5 JIt nail part, the effect of the present invention will not be noticeable, and if it exceeds 15 JIt nail part, pluminda m* etc. will occur, resulting in unfavorable results. may be given.

In general, magnetic paint has magnetic powder, binder, and coating tip as its main components, and in addition, dispersants, lubricants, abrasives, etc. as necessary.
Contains additives such as band 1a inhibitors.

This magnetic paint is prepared by dissolving and dispersing the composition described above in an organic solvent, and is applied onto a non-magnetic support to form an arsenic recording layer.

Regarding the manufacturing method of the magnetic paint used in the present invention,
No. 5-15, No. 39-26794, No. 43-186, No. 47-2°8043, No. 47-28045, No. 47-28046, No. 47-28048, No. 47-
No. 31445, No. 4B-11162, No. 4B-213
No. 31, 4B-33fi No. 83, Soviet Union'IX? It is described in detail in various publications such as Xu Ming #III No. 308033.

As the binder used in the present invention, thermoplastic M resins, thermosetting resins, reactive resins, electron beam irradiation-cured resins, and mixtures thereof, which have been known since then, are used. It is stated in the specification of the No. These binders may be used alone or in combination, and other additives may be added as necessary. #P-The mixing ratio of magnetic powder and binder is 4 years.

The binder is used in an amount of 10 to 400 parts by weight, preferably 20 to 200 parts by weight, per 100 parts by weight of the magnetic powder. If the amount of the binder is too large, the recording density of the magnetic recording medium will decrease, and if the amount is too small, the strength of the magnetic recording layer will be poor, resulting in undesirable situations such as decreased durability and powder falling off.

In the magnetic recording layer containing the compound of the present invention, a dispersant other than the present invention may be used as an additive in addition to the binder and magnetic powder described above, and also a lubricant and an abrasive. , an antistatic agent, etc. may be added.

Regarding dispersants, Rft agents, and abrasive agents to be used in combination, see Japanese Patent Application No. 137-8697.3. Regarding the organic solvent and non-magnetic support used,
This is clearly described in Japanese Patent Application No. 57-813973.

- The thickness of the magnetic support is approximately the same as that of a film or sheet; in the case of a drum, it is cylindrical, and its shape is determined depending on the pressure of the recorder used.

The above non-magnetic support has a surface opposite to the side on which a magnetic recording layer is provided for the purpose of preventing static electricity, preventing transfer, etc.
(Backaoat) may be used.

Regarding back court VC, for example, US UgJ special n'r
m2.804,401, m2.804,401, m2.3,293,060,
3.617,378, 3,062,676, 3.734,772, 3,476, 59
No. 6, - No. 2,643,048, No. 2,803.
No. 5156, No. 2.887,462, rn2.9
No. 23,642, No. 2.997,451, No. 3,
No. 007,892, No. 3.041,196, In
It is described in various specifications such as No. 3,115,420 and No. 3,166.688.

Further, the support may be in any form such as a tape, sheet, card, disk, or drum, and various materials may be selected as necessary depending on the form.

Magnetic powder, the aforementioned binder, dispersant, lubricant, abrasive, antistatic agent, solvent, etc. are kneaded to form a magnetic paint.

During kneading, the magnetic powder and each of the above-mentioned components are fed into a kneader either simultaneously or individually one after another. For example, there is a method in which magnetic powder is first added to a solution containing a dispersant and kneaded for a predetermined period of time, and then the remaining nine ingredients are added and kneading is continued to obtain a magnetic paint.

Various types of kneading machines are used for cross-mixing and dispersion. For example, two roll mill, three roll mill, ball mill, four pull mill, sand grinder τ-1Szegv=rl
These include attritor, high-speed impeller dispersion general-purpose high-speed stone mill, high-speed impact mill, Disper Kneader-1 high-speed mixer, homogenizer/ultrasonic dispersion machine, etc.

The technology related to crosstalk dispersion is T, C, PATTON M
Paint FIOW and P1gm7nt Di
spersion (1904 John W mouth lay
& 5ons, Inc.)

Maf-U.S. Pat. No. 2,581,414, U.S. Pat. No. 2,85
5゜156 It is also mentioned in each specification of sound.

The coating method for coating the magnetic paint onto the support to form the magnetic Fn3 recording layer includes Step 1-Doctor coating;
Blade coat, air knife coat 1 squeeze coat, impregnated foot coat, reverse roll coat, transfer roll coat, clavier coat, kiss coat, cast coat, spray/r coat, etc. can be used, and other methods are also possible, and these specific methods The explanation is published by Breakfast Shoten.
Coating Engineering” pp. 253-277 (March 1972)
month (i) day/issue) [details are given.

By such a method, the magnetic recording layer coated on the support is optionally treated to orient the magnetic powder in the layer, and then the formed magnetic recording layer is dried. Further, the magnetic recording body of the present invention is manufactured by subjecting it to surface smoothing processing and cutting it into a desired shape, if necessary.

In this case, one orientation magnetic field is approximately 500 to 20
00 Gauss and the drying temperature is about 100"
The drying time is approximately 3 to 10 minutes.

The method of orienting magnetic powder is also described in the patents listed below.

For example, U.S. Pat.
．． No. 796,359, No. 3,001,891, No. 3,172,776, No. 3,416,949, No. 3.473.96Q, No. 3,681,138. Specifications, Japanese Patent Publication No. 32-3427, No. 39-2836
No. 8, No. 40-23642, No. 40-23625,
No. 41-13181, No. 4B-13043, No. 4B
-39722, etc.

(1. The orientation direction of the magnetic material is determined by its use. In other words, in the case of sound tape, small video tape, and memory tape, it is parallel to the length direction of the tape, and in the case of broadcasting video tape, it is parallel to the length direction of the tape. They are oriented with an inclination of 30° to 90° in both directions.

The present invention will be explained in more detail below using examples.

It will be readily understood by those skilled in the art that the ingredients, proportions, order of operations, etc. shown herein may be modified without departing from the spirit of the invention.

The magnetic recording medium of the present invention can be used not only for audio, video, and computers, but also for magnetic cards, magnetic sheets, magnetic disks, magnetic drums, and the like.

Therefore, the present invention should not be limited to the following examples. In addition, in the following examples, all "capital" indicates "overlapping part".

Examples 1 to 5 Exemplary compounds (,) to (,) shown in Table 1 below were diluted with 500 parts of methanol, and 100 parts of magnetic powder was added and mixed and dispersed. Thereafter, it was heated and dried to produce treated magnetic powder.

Table I A small amount of the above treated magnetic powder was sampled and a flushing test was conducted in a water-toluene system, whereupon the treated magnetic powder completely migrated to the organic layer. The untreated magnetic powder remained in the water layer, indicating that the surface of the magnetic powder had been modified.

Using the thus obtained magnetic powder, a magnetic tape was prepared with the following composition.

The above composition was placed in a ball mill, thoroughly mixed and dispersed, and then 5 parts of incyanate curing agent was added to obtain a black magnetic paint. This paint was dried on one side of a polyethylene terephthalate film with a film thickness of 15 microns while applying a magnetic field.
It was coated to a thickness of 5'-6μ.

The thus produced wide iJ magnetic wave was supercalendered and slit into 12.7 mm diameter II to obtain a videotape.

The tape was prepared according to the treated magnetic powder 161 and % 165, and the tape was designated as magnetic tape sample 161-5.

Examples 6 to 1° Exemplary compounds (a) to (d), (r) shown in the table below, -2
was diluted with 500 parts of methyl ethyl ketone, and a magnetic alloy (F
100 parts of s-HCo-Nl) were added and mixed and dispersed.

After heating and drying, treated magnetic powder was produced.

Table 2 C: Using the returned magnetic powder, the above composition with the following composition was put into a ball mill and thoroughly mixed and dispersed, then 3 parts of tolylene diisocyanate was added and mixed uniformly to make it magnetic. Got the paint.

This paint was applied to one side of a polyethylene pre-7 tallate film having a thickness of 15 microns while applying a magnetic field to a dry film thickness of 5 microns. Magnetic tape samples 6 to 10 were prepared using the thus obtained wide IR samples in the same manner as in Examples 1 to 5.

Example 11 The above composition was placed in a ball mill and thoroughly mixed and dispersed to obtain a black magnetic paint. Example 1 using this salary
A videotape was obtained in the same manner as in 5. This tape is referred to as tape sample-IJ.

Example-12 The above composition was sufficiently dispersed in a ball mill to obtain a coating liquid.

The resulting viscous coating solution was applied onto a polyethylene ester film so that the final film had a thickness of 5 μm, and immediately heated to 2 m@ Irradiation was carried out at a dose rate of grad/m@e to give an absorption radiation of 10 msgarad. The binder system is immediately cured by this electron beam irradiation, and the expanded tape is then passed through a drying zone at 80-110°C to completely evaporate the low boiling point solvent and slit to obtain a video magnetic tape. 12.

Comparative Example-1 Untreated Co-containing F'@1 instead of surface-treated magnetic powder
1. Same as Example 1 except that 041r:-). A videotape was made. This will be referred to as Comparative Sample-1.

Comparative Example 2 A videotape was prepared in the same manner as in Examples 1 to 6 using #l or 11 magnetic alloy (Fe-Co-Nl) instead of the magnetic powder treated with a surface treatment agent. . This will be referred to as Comparative Sample-2.

Comparative Example 3 The above composition was placed in a ball mill and thoroughly mixed and dispersed to obtain a black magnetic paint. A videotape was obtained in the same manner as in Example 1 using this paint.

This tape will be referred to as Comparative Sample-3.

Comparative Example 4 The above composition was placed in a ball mill and thoroughly mixed and dispersed to obtain a black magnetic paint. Using this paint, a videotape was obtained in the same manner as in the previous example.

This tape will be referred to as Comparative Sample-4.

This was prepared and designated as Comparative Sample-5.

49.75 molty ethyl acrylate, 49.75 molty ethyl acrylate, 0.5 molty 3-chloro-2-acid phosphooyaciglovir methacrylate] were used to prepare a sample, and a comparative sample = (tfi: prepared).

Check out the comparative test results for these videotapes! -3.

Table 3 Note: a) Surface roughness is the value of the center line average roughness measured using a surface roughness gauge.

b) Set the v1° deck for RF output measurement /Tf 4
The RF output at Mftz was measured and shown as a relative value with O being the output of Comparative Sample-1.

C) Abrasion resistance was measured by repeatedly sliding a t3rrL length tape back and forth at a speed of 7m/sec using a simulated head.
The subsequent deep surface was determined visually and using a microscope.

d) Adhesiveness was determined by the occurrence of sticking after being left for 24 hours at a humidity of 80 degrees Celsius and a temperature of 40 degrees Celsius.

From the above results, the magnetic recording medium according to the present invention is a high-density magnetic recording medium that has better dispersibility, surface properties, wear resistance, storage stability, and higher reproduction output than conventional ones. I know something, Karu.

Agent Yoshi Kuwahara Beautiful Procedural Amendment September 7, 1980 Patent No. 1 Commissioner Kazuo Wakasugi 1, Matter I'1 J, 1981 Application No. 134543 2, Name of Invention Magnetic Recording Medium 3 Supplementary Relationship with the Nagisa Incident No.1ll'l'IlltXi Resident
Address: 1-26-2 Nishi-Shinjuku, FFI-ku, Tokyo Name (127) Rokusha Konishi J-7: , - Jl Gyo Co., Ltd. Address: 1-6 Sakura-cho, II'JLF City, Tokyo
Column 7 of ``Detailed Description of the Invention'' in the Specification Subject to Amendment Contents of the Amendment (a) Correct the lock in ``Detailed Description of the Invention'' as described above.

(1) Page 10, line 1J, “... Magnetism 1
Form 11 recording layers. ” all [... form a magnetic recording layer.

The magnetic powder C according to the present invention is, for example, r-F@4Q
3 powder, Fe3O4 powder, CO containing powder, F'1tOs powder, and powder are widely included. ” he corrected.

Procedural Amendment 1, Matter 1'l Indication 1977 'I '+'r Il'l' l+ill
No. 134543 -'j2 Name of the name Magnetic Recording Medium 3 Capture 11. Relationship with Famous Things I'1 'IF? :l'l' II Geji
Staff East J; 1 Tokyo 1i Inn V Nishi-Shinjuku RL'112B
'r21; Name (I), (+27) Konishi Roku'noj'↓
jj, +- industry (Sueyozu Prize 1st Generation 1st Law Deceased Nobuhiko Kawamoto 1st 1 Tokyo f 1st 1st Machiyama Sakura Town l ili land 6゜ Detailed explanation of ``U''1'' of the invention in the specification subject to amendment 'Ill#7,
Contents of the amendment: “Detailed explanation of the invention.

(1) f' Ii from the 1st line to the 5th line from the top of page 16
The orientation direction of the l11'b body should be oriented with... ” to be deleted.

Procedural amendment IMJ 和5847711ri +-+%jil'l
Director-General Kazuo Wakasugi 1, Matter A'1 Blueprint 1982 1981 Application No. 134543 υ2 Title of Invention Magnetic Recording Medium 3, Supplementary JlE. 8 Relationship to the incident Patent applicant address 1-26 Nishi-Shinjuku, Shinjuku-ku, Tokyo ffi 2
Name (+27) Konishiroku Photo Industry Co., Ltd.? l.

Representative Director Nobuhiko Moto Nobuhiko Notification Office 111 Sakura-cho, Meno, Tokyo I1 Konishiroku Photo-1-Industry Stock Exchange II-Inner 6゜Amendment to Column 7 of "Detailed Description of the Invention" of the Specification Subject to Amendment The contents of the "Detailed Description of the Invention" are corrected as follows.

1, Page 5, Table 3, 4th column rRF Output (dB) b) j to r RF
Out 1+put (mVp-p)b) J and li
J Correct.

Claims (1)

[Claims] 1. A magnetic recording medium comprising a polymer compound having at least one monomer unit having a negative organic group as a copolymerization component, the organic group forming a wall.