JPS62139118A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the durability, magnetic characteristic, and electromagnetic transducing characteristic of the titled medium by incorporating an acrylic ester copolymer having a tertiary amine in the molecule into the magnetic layer as a binder. CONSTITUTION:A magnetic layer consisting essentially of ferromagnetic powder and the binder is formed on a nonmagnetic carrier to obtain the magnetic recording medium. The acrylic ester copolymer having a tertiary amine in the molecule is incorporated into the magnetic layer as the binder. The copolymer consisting of an acrylic ester obtained by introducing a tertiary amine into so-called acrylic rubber as a polar group is used as the acrylic ester copolymer to be used as the binder of the magnetic layer. Acrylic rubber is highly elastic and resistant to shock and has excellent resistance to water and oil and adhesion to the base film as the nonmagnetic carrier. The content of the acrylic ester is controlled to 95-50wt%. Consequently, the durability and surface property are improved, and the electromagnetic transducing characteristic is extremely ameliorated.

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 an electromagnetic recording medium (in a magnetic recording medium in which a magnetic 11 layer consisting mainly of ferromagnetic powder and a binder is formed on a support 11, in which a magnetic layer is included in the binder constituting the magnetic layer). By using an acrylic acid ester copolymer having a tertiary amine, the dispersibility of the 6D powder and the surface of the magnetic layer can be improved. The objective is to improve the physical properties of the coating film of the magnetic III layer and to improve the durability, magnetic properties, electromagnetic conversion properties, etc. of the resulting magnetic recording medium.

[Conventional technology]

In recent years, in magnetic recording media, especially magnetic recording media for VTRs (video tape recorders), there has been a demand for improved magnetic properties and electromagnetic conversion properties in order to obtain high playback output even when recording at short wavelengths. has been done.

As a measure to this end, efforts have been made to make the magnetic powder particles finer and to increase the magnetic force, and there is a strong tendency to increase the packing density of the magnetic powder in the magnetic layer, the so-called panodensity.

- Tsuno, Conventional (H'be) As a binder for recording media 7,
Chloride, drink, drink! Chlorinated heel-based binders such as chlorinated nylbucopionic acid copolymer, chlorinated vinyl-vinyl acetate copolymer, etc. are used. When the hydroxyl group of the -ru or the magnetic powder's part 11, the 3L of hydroxyl and the 1 hydrogen of the hydroxyl react with the isocyanate compound, etc. to form a C bridge + 14 structure. C) Vinyl chloride Hinyl acetate Polymers are widely used.

However, although it is L7, there is an increase in the number of people mentioned above, and further demands such as 1.
, 2 (1: Various problems occur with these binders containing vinyl chloride) 1: L, and the current situation is that the sufficient / 1 month is not enough.

For example, by increasing the specific surface area by making the 661 Noro 5) fine particles and by increasing the cohesive force by increasing the flocculation force, the above-mentioned binder can be used to increase the specific surface area. +V+ Some amount of +ti Hk I'
It is difficult to obtain good surface properties, and increasing the backing density of the magnetic powder also results in 4). Therefore, even 1.1 was sufficient for 11i + durability, magnetic properties, and electromagnetic conversion of 4 yen 14. In particular, the 1st prize that focused on high recording density was ll't 14
H'i, 'I11i) if +'
There are 171 incompetent iJ things that are not enough for the first time. In this case, for example, there is no way to think of a method such as using a surface-active agent as a 1-11 (agent), but if the surface-active agent is
Since the I agent is paper-sized, does it cause +jl drop or blooming due to changes over time? However, there are problems with mechanical strength and durability.

Furthermore, when a series of vinyl chloride binders are used, the flexibility of the magnetic layer slightly decreases, so it is necessary to add a large amount of plasticizer or to use a large amount of each type of soft resin. There is. As a result, in the case of the 1iii layer, there is a risk of problems such as increased blooming and a decrease in the durability of the 1 layer, and in the latter case, the ferromagnetic There is a risk that the value +lk +'i may deteriorate, or there may be problems with running performance in hot and humid conditions.

[Problem that the invention seeks to solve]

As shown above, there are many issues that need to be solved in terms of the dispersibility of conventionally widely used vinyl chloride copolymers (Y, magnetic ↑) powder, coating material M, etc., and the specified durability 1ψ1. The power is 1 for every electric power conversion '1' + 1').
It was true.

Therefore, the present invention has been devised to solve the above-mentioned drawbacks of the 51 fields of the art, and provides a binder resin with excellent dispersibility and coating film properties for 4(i 1'l powder). death,
The purpose is to provide a magnetic recording medium with excellent durability and good magnetic properties and electromagnetic conversion properties.

[Means for solving problems]

The present inventors and others have been working for a long time to achieve the above objectives.As a result of research, we have found that acrylic ester copolymers have good flexibility and that polar groups can be used as side chains. They discovered that each time a tertiary amine is introduced, a higher affinity for magnetic powder is exhibited, and the present invention was completed. and a binder, in which the binder contains an acrylic ester copolymer having a tertiary amine in the molecule as a binder. It is characterized by:

The acrylic ester copolymer used as the binder for the magnetic layer in the present invention is a copolymer mainly composed of acrylic ester, so-called acrylic rubber, into which a tertiary amine is introduced as a polar group. Acrylic rubber is
It is highly elastic and can withstand impact, and has excellent water and oil resistance. Furthermore, it has excellent adhesion to the base film, which is a non-magnetic support. Therefore, it is suitable as a binder for magnetic recording media that require flexibility, such as magnetic tapes and floppy disks.

The acrylic ester constituting the above acrylic ester copolymer includes methyl (meth)acrylate, (
Ethyl meth)acrylate 1 Propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, and the like.

In addition to these acrylic esters, C containing a monomer copolymerizable with the acrylic ester as a third component may also be used.

! Examples of seven polymers copolymerizable with theacrylic acid esters include hinyl chloride, hinyl acetate, hinyl alcohol,
Examples include maleic acid, maleic anhydride, acrylic acid, 2-methacrylic acid, styrene, acrylic nitrile, and nitrile nitrate. One or more of these polymers are selected and copolymerized depending on the solvent and
＼ solubility and coating film flexibility P13 ferromagnetic + 'l powder dispersion +
2+, isocyanol, -1-, and other curing agents.

However, in this case, the proportion of acrylic ester is
(It is preferably in the range of 35 to 50% by weight; if the self-sufficiency of the -1 acrylic acid sprue is less than 50% by weight, the original acrylic acid ester copolymer's 4\ characteristic will be lost, e.g. The SN ratio deteriorates.

On the other hand, as a method for introducing a tertiary amine into the above-mentioned acrylic ester copolymer, the following method can be considered, for example.

A. One that can be copolymerized with an acrylic ester copolymer]
A method of copolymerizing a monomer that connects a heavy bond and a tertiary amine with an acrylic ester.

It has an acrylic group or a methacrylic group in its pores and a tertiary amine, specifically, 1) R' [:11□・CC00( CI+□) 2N(R) xl
l) Iin' CIl□=CC0N11(C1lz)J(Iin)2ii
i) R' C112・SCo0(CI+2) JN(R)2CIl
□, t: c ON II < c o□) 311
(R) 2) (Tatashi, in the formula, R+J represents an alkyl group having a carbon atom number of 1 to 4, R' represents 11 or +; L CII 3, respectively), and the like.

F3. Acrylic acid: A method in which a functional group introduced into the terminal or side chain of an l-stellate copolymer is modified with a compound having a tertiary amine.

This method can be divided into the following two methods depending on the type of functional group introduced into the acrylic ester copolymer in advance.

After copolymerizing a monomer with a double bond capable of copolymerizing with an acrylic acid ester and an active hydrogen with an acrylic acid ester, the monomer is modified with a compound having a group capable of reacting with active hydrogen and a tertiary amine in the molecule. How to do it.

Examples of a compound having a double bond and an active hydrogen that can be copolymerized with the above acrylic ester include R' C11□=CCOO(CI+2) zollll) R'011 C11□+, CC00C112CIIC1h (however,
In the formula, R' represents II or CHJ. ) and other yahinel alcohols.

In addition, as a compound having a group capable of reacting with the above active hydrogen and a tertiary amine in its molecule, number J, for example, OCN' 1i) OCN'C# (CIlz) J(R)z 1ν) C1 (CI+2) J (R) Z (However, in the formula, R does not represent an alkyl group having 1 to 4 carbon atoms. ) etc.

([32) Double bond and active P [
What is the name of a group that can react with hydrogen? Total acrylic acid sufur and 1 (undercarriage U7, active 1'l hydrogen and tertiary amine ♂ > 7, natural compound 1 reno and change 1'``rai.''

Nonon J.

l- Atarylic acid ester and! (Polymerization
'j+'i combination and a monomer having a group capable of reacting with active hydrogen and U'C are, for example, CIl□-CCO (IcII, CIl C1l□1
・, /'1' O (however, 7,] (middle R' i, 1.11 or C113
Table 1゜) etc. N) et al.

In addition, ] Cheno 1 water A;
(C11□), N(ρ).

110 (Cllz) J (+n) 2 (just t2, Boshin R (1 carbon original number 1 to 4 °? Luha 1
1-1', acrylic acid: 1-sulfur system! The atomic molecule of the mass medium body! - is 500 (] ~I O0
0000) range and deviation is desirable. This minute (ill
If it is a 5,000,1-n crystal, the coating film-forming ability will be insufficient and the durability of the recording medium will be poor. ,
The solubility in solvents deteriorates, and it is difficult to mix and transport for paint manufacturing.
There is a risk that problems will occur in the processing of P cloth, etc.

In addition, the amount of tertiary amine introduced into the acrylic acid ester copolymer described in 1-1. Preferably, the amount of tertiary amine introduced is (1,0] mmo//
If it is less than 1.g, the dispersion effect for strong lamination powder will be insufficient, and conversely, 1. If it exceeds ommol/g, the solubility in the solvent will deteriorate and the moisture resistance of the resulting coating film will also deteriorate.

Of course, the tertiary amine-containing acrylic ester copolymer may be mixed with other binders.

As such a binder, those conventionally used as a binder for magnetic recording media can be used, including vinyl chloride-vinyl acetate copolymer, vinyl chloride acid-resistant vinyl ruby vinyl acetate copolymer, chloride hinyl-acetate-hinyl-maleic acid copolymer, hnylidene chloride copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride-7-nitrile copolymer, thermoplastic polyurethane resin,
Phenoxo resin, polyvinyl fluoride, vinylidene chloride acrylic 1 nitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, polyvinyl butyral, cellulose derivative, styrene-butadiene copolymer, Examples include polyester resins, phenolic resins, epoxy resins, thermosetting polyurethane resins, urea resins, melamine resins, alkyd resins, urea-formaldehyde resins, and mixtures thereof. Among these, polyurethane resins, polyester resins, acrylic 1 and 1-lyl butadiene copolymers, etc., which are said to have flexibility (=j), are preferred.

Either way, L, the tertiary polar group in these binders.
Polar group equivalent of class amine (polar JA, molecular weight per unit)
is preferably in the range of 1,000 to 100,000. If this polar group equivalent exceeds 100,000, no effect can be expected; if it is less than 1,000, the effect does not change much, and the resistance to l! ! A problem arises in that l't.

In the magnetic recording medium of the present invention, the magnetic layer may include, for example? I
It is formed by coating the surface of a non-magnetic support with a magnetic paint prepared by dispersing J magnetic powder in the above-mentioned binder and dissolving it in an organic solvent.

Here, the ferromagnetic powder used for the -1-magnetic layer has i
Any conventional one can be used. Therefore, examples of the ferromagnetic powder that can be used include ferromagnetic iron oxide particles, ferromagnetic carbon dioxide, strong n-type alloy powder, hexagonal halium alloy powder, iron nitride, and the like.

-F ferromagnetic iron oxide particles have the general formula F' e O
When expressed as x, the value of
, 0,.

X-1,50) ,"/g, 6 tight (1-' e 3
04. X -1,33) and their solid solutions (l'
(!Ox, 1.33<X<1.50). In addition, ferromagnetism 1 biooxidation 1 loss: 1. It is also good to add cobalt and ζ to increase coercive force. -There are two types: zo type and adherent type.

As the strong chromium dioxide, CrO2 or R11°S is used for the purpose of imparting coercive force to these.
n, Te, Sly, Fe, Ti, V, 1
A material containing at least one type of yln or the like can be used.

The ferromagnetic 1-no-1 alloy powder includes Fe, Co, and Ni.

Fe-co, To”e-Ni, Fe-Co-Ni, Co-
Ni, Fe-Go-R, Fe-Co-Cr-R3, M
n-f'(i, Mn-Al!, Fe-Co-V, etc. can be used, and in addition, Al, Si, Ti, Cr, Mn, Cu can be used for the purpose of improving various properties.

A metal component such as Zn may be added.

Furthermore, the above ti (the outer layer contains the above-mentioned binder and ferromagnetic material)
In addition to the powder, dispersants, lubricants, abrasives, antistatic agents, rust preventives, etc. may be added as additives.

- Dispersants (αn\'l?W! lubricants) include caprylic acid, dicapric acid, lauric acid, myristic acid, palminic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, dilyrinic acid, and stearol. Fatty acids with 12 to 18 carbon atoms such as acids (RI CO(1tiR+
is an alkali metal (Li, Na, etc.) or alkaline earth metal (Mg, Ca, F3a, etc.) of the above-mentioned fatty acids, Fluorine-containing compounds of the above fatty acid esters, amyl-I8 polyalkylene oxylyte alkyl phosphate esters of the above fatty acids, trialkyl poly'resoinoxy quaternary ammonium salts (alkyl has 1 to 1 carbon atoms)
511L olefins are ethylene, pyrene, etc.),
etc. is 1! l! Become a river. In addition, carbon number 12 or more].

Higher alcohols, and in addition to these, sulfuric esters and the like can also be used. The dispersant is added in an amount of 05 to 20 parts by weight per 100 parts by weight of the binder.

As the lubricant described in , dialkylporin 1.1 Kizan (
Alkyl tJ carbon number 1 to 5111.1), dialkoxyboryle 11xane (alkoxy has 1 to 4 carbon atoms), monoalkyl monoalco"-siborisiloxane (alkyl 4 to 4 carbon atoms)
Number: (1 to 5 carbon atoms, alkoxy has 1 to 4 carbon atoms), phenyl polysiloxane, fluoroalkyl polysiloxane (alkyl has 1 to 5 carbon atoms (IM), etc. Conductive materials such as silicone oil, graphite, etc. Fine powder, inorganic fine powder such as molybdenum disulfide 5-tungsten sulfide, polyethylene, polypropylene 2 polyethylene-vinyl chloride copolymer, plastic fine powder such as polytetrafluoroethylene, α-olefin polymer, non-liquid which is liquid at room temperature. Saturated aliphatic hydrocarbons (compounds in which an n-olefin double bond is bonded to the terminal carbon, approximately 20 carbon atoms), monobasic fatty acids with 12 to 20 carbon atoms, and monovalent fatty acids with 3 to 12 carbon atoms Fatty acid esters consisting of alcohols, fluorocarbons, etc. can be used.These lubricants are added in an amount of 0.2 to 20 parts by weight per 100 parts by weight of the binder.

The above-mentioned abrasives include commonly used materials such as fused aluminum silicon carbide, oxidized IIJ rubber (Cr20),
Corundum, artificial corundum, diamond mono l-1 artificial diamond, garnet, emery (main components: corundum and +rt iron ore), etc. are used.

These abrasives have a Mohs hardness of 5 or more and an average particle diameter of 0.05 to 5 μm, particularly preferably 0.1 to 2 pm. These abrasives are added in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the binder.

The anti-static agent described in 2.1 is carbon black.

Conductive fine powder such as carbon blank graft polymer,
Natural surfactants such as saponin, nonionic surfactants such as alkylene oxide, glycerin, and glycidol, and higher alkylamines.

Quaternary ammonium salts, pyridine and other heterocycles,
Cationic surfactants such as phosphoniums, carboxylic acids,
Anionic surfactants containing acid fi [groups such as sulfonic acid, phosphoric acid, sulfuric acid ester groups, and phosphoric ester groups, amino acids, and aminosulfonic acids.

Aminoal: Acid or phosphoric acid ester, etc. are used. The month is 7 and 0
．． 2-20 wheel engagement part is surfactant 11 agent It: o, 1-
It is added in an amount of 10 parts by weight. These surfactants may be added in combination. These are used as anti-static agents, but they are sometimes used for other purposes such as dispersion, improvement of temperament, improvement of lubricity, coating aids, etc. may also apply.

1- Rust inhibitors and U7 include phosphoric acid, sulfamide, guaconedine, pyridino, amine, urea, non-compound 1 fumate, cal-nin llimku lj mate, and sulfamide
, Kurome-1, etc. are used (Kiruga, especially Shishiku II Hexyl Ryo Minnoi 1 Light, Schiff [1. Hegisyl ammonium, carbonate, hexamethylenecyamine carbonate-1, pyrene diamine stearate,
Guani: non-carbonate-1-, triethanolamine li'-i1)-i1, vaporized 1-l', l! Ij rust agent (amine, -memi 1 or (
Use J garbage 1 inorganic acid JλA 1, tti machine consideration) 4 and rust prevention AI + effect direction l-'4. Konera's rust preventive agent (1 strong T (juice 15)
．． O1~20 Monkeys! The range of the d part (to be used).

In addition, (it l' 1 layer configuration 4411 i; , That Yuu+
'l-coating 11's composition rule t7 (is Al-1, methyl ethyl getone, methyl isozotyl' J-ton.

Tsunoton series such as cyclo・＼;1sanon, acetic acid mail,
Ethyl lactate, butyl acetate, ethyl lactate, gly-1-acetate
- [ster system, glyph 1-l 7-noethyl ether, etc.
Glycols such as diochirin: [-Fur type, Hensen,
Toluene, 4-silene, etc. aroma! i 85 Hydrocarbon, hexane. Aliphatic hydrocarbons such as heptane, ethytone chloride 1. Carbon Tetrachloride, Riichi''ll Hol J.

Examples thereof include chlorinated hydrocarbons such as ethylene chloride] phosphorus and dicou'Jruhenzen.

In particular, the above-mentioned magnetic paint contains iri it1 layer of iii+
In order to increase +r<wear +'t and heat resistance, a di- or -1 functional .isocyane 1 compound or the like may be kneaded if necessary.

By adding these difunctional or higher-functional isocyanyl compounds, crosslinking (!) reaction is promoted and a coating film with excellent mechanical strength is formed.

The non-magnetic support to which A il is applied may be polyester li'i such as polyethylene 1/n terephthalate, polyethylene, polyolefins such as polyp I:I pyrene, cell l' l-striacetate,
Cell 1: Cell 11-su derivatives such as I-nudiacetate and July 1-suacetatezotylate, vinyl resins such as polyvinyl chloride and polyhynyritene chloride, polycarbonate-1, polyimide 2-bolyamitoimi, etc. Plus 1,000, etc. are used. The form of the non-magnetic support described in -1- may be any film, tape, disk, card, tram, etc.Alternatively, the form of the non-magnetic support described in -1- may be aluminum, J, alloy, titanium, etc. It is also possible to use a light alloy such as alloy, thermoplastic resin such as polystyrene, ABS resin, ceramics such as alumina glass, single crystal silicon, etc. to form a so-called bart disk. In this case,
The surface of the support is preferably hardened by providing a rough Ni-P plating layer or by alumite treatment.

In addition, it is also possible to utilize the acrylic acid ester copolymer containing the above-mentioned tertiary amine as a binder for the Huck-1-1 layer, the IT layer, and the like.

[Effect]

As mentioned above, by using an acrylic acid ester copolymer having 11 tertiary amine groups in the molecule as a binder, the affinity for magnetic powder is greatly improved and ultrafine particles can be obtained. Even magnetic powders such as magnetic powders with a large amount of magnetization are well dispersed.

Furthermore, due to the good flexibility, adhesion, etc. of the acrylic acid ester copolymer, a coating film with excellent durability is formed as a magnetic layer.

〔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, various 4AI fats were synthesized by the following method.

Resin synthesis example 1゜Butyl acrylate 80% by weight 2-10xyethyl acrylate-1-15ffiit% (:1
1□・CII CON II (CII□)J(C1h
) z 5% or more of the composition is copolymerized to a number average fractional yield u10000.1! Resin A was obtained.

Resin Synthesis Example 2 The same composition as in Resin Synthesis Example 1 was prepared with a number average molecular weight of 300.
Resin B was obtained by copolymerizing the resin to 0.00.

Resin Synthesis Example 3 The same composition as in Resin Synthesis Example 1 was prepared with a number average molecular weight of 50.
Copolymerization was carried out to obtain Resin C.

Resin synthesis example 4゜Butyl acrylate 80% 2-hydroxyethyl acrylate 15% C1l□-C
IICON)l (Ci1□)2N(CZII5)2
The number average molecular weight of the composition is 5% or more.
000 to obtain a resin.

Resin synthesis example 5゜Butyl acrylate 83% by weight 2-hydroxyethyl acrylate 15% by weight C11□=C
lIC0NII(CIl=)J(C1h)z
Resin E was obtained by copolymerizing 2% by weight or more of the composition to a number average molecular weight of 110,000.

Resin synthesis example 6゜Butyl acrylate 78% by weight 2-hydroxyethyl acrylate 15 heavy electric C11□-C
IICONH(CI+2)2N(C13)2
Several thousand equal parts of a composition of 7% by weight or more - 7'110000
Resin F was obtained by copolymerizing the resin.

Resin synthesis example 7. (Comparative example) Butyl acrylate 85 deuterium 2-h10 xyethyl acrylate Number average molecule of composition of 15 deuterium or more! The resin was copolymerized to +0000 to obtain Resin G.

Resin synthesis example 8. (Comparative example) The same composition as in the previous resin synthesis example 7 was prepared with a number average molecular weight of 300.
Resin H was obtained by copolymerizing the resin to 0.00.

Resin synthesis example 9. (Comparative example) The same composition as in the previous resin synthesis example 7 was prepared with a number average molecular weight of 1i50.
000 to obtain Resin 1.

Using the resin synthesized as described above, a magnetic recording medium was produced by the following method.

Example 1゜Co coated r-Pe, 0. , 100
Parts by weight (specific surface area 35 td/g) Resin A 12 parts Vinyl chloride-vinyl acetate-vinyl alcohol copolymer (11
, c, manufactured by c company, VAGI+) 8 parts dimethyl silicone oil (lubricant) 1 part lecithin (dispersant) 1 part Cr2O3 (abrasive) 2 parts methyl ethyl ketone 1001 parts methyl isobutyl ketone 50 weight part toluene
50 parts by weight of the above composition in a ball mill
After mixing for 8 hours and filtering through a 3 μm filter, 2.5 parts by weight of a curing agent (Desmodur I, manufactured by Bayer AG) was added, mixed for an additional 30 minutes, and one film of polyethylene terephthalate with a thickness of 14 μm was added. ''Second, it was coated so that the film thickness after drying was 6 μm. Next, after performing a magnetic field orientation treatment, it was dried and wound up. This was supercalendered and then cut to a width of 172 inches to produce a sample tape.

Example 2 A sample sample was prepared by the same method b as in Example 1 except that resin C and resin B were used instead of resin.

Example 3 A simple tape was produced in the same manner as in Example 1 except that Resin C was used instead of Resin A.

Example 4 A 3L rimple tape was produced in the same manner as in Example 1 except that a resin was used instead of the resin.

Example 5 A sample tape was prepared using the same horn method as in Example 1 except that resin E was used instead of resin A.

Example 6 A sample tape was prepared in the same manner as in Example 1 except that Resin F was used instead of Resin A.

Comparative Example 1 Eleven rimple tapes were manufactured using the same horn method as in Example 1 except that Resin G was used instead of the resin.

Comparative Example 2 A sample tape was prepared in the same manner as in Example 1, except that Resin 11HI+ was used instead of Resin A.

Comparative Example 3 A simple tape was produced in the same manner as in Example 1 except that Resin I was used instead of Resin A.

For each simple tape obtained, ζ, 11 surface gloss, powder removal, and still characteristics n were measured.

In addition, the surface gloss listed above is gloss iii (G1.O3S
MET1! R), the angle of incidence is 75° 1 inverse 11 angle 75
The reflectance at LJ was measured. In addition, powder fall is 60
After running the minute shuttle 100 times, the amount of powder falling on the heno drum, guy I, etc. was visually observed and evaluated using the point deduction method (-5 to 0). For the still characteristics, a 4.2 MIIZ video signal was recorded on a sample tape j+, and the playback output was 50
It was defined as the time it takes to decay to %. The results are shown in the table below.

(Left below) As is clear from the table, it is grade 3'? By using an acrylic ester copolymer containing amine as a binder, surface gloss and powder shedding are improved, and still durability is significantly improved.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
An acrylic ester copolymer having a tertiary amine as a polar group in the molecule is used as a binder for the magnetic layer. Even if it is a powder with a large amount of magnetization or a large amount of magnetization ((i), it will be a good dispersion ('I). medium 1
1i4 durability 1 surface 11 is improved and electric 451 conversion characteristic 11 is also extremely excellent.

In addition, due to the flexibility of the acrylic ester copolymer, the addition of a plasticizer can increase the flexibility to at least 11.
It is possible to form an i +/1 layer, and it also has excellent adhesion to the support +ii, and the durability is improved in these respects as well.

Claims (1)

[Scope of Claims] A magnetic recording medium in which a magnetic layer mainly composed of ferromagnetic powder and a binder is formed on a non-magnetic support, wherein the magnetic layer is made of acrylic acid having a tertiary amine in its molecules. A magnetic recording medium characterized by containing an ester copolymer as a binder.