JPS58185027A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve lubricity, by providing a lubricating layer on a coating film using a binder which has a polar group in the side chain of a molecular structure. CONSTITUTION:There are, for example, a vinyl chloride-vinyl acetate-vinyl alcohol copolymer, a polyester resin, a polyurethane resin, etc. as a compd. that has a polar group contg. an -OH group, -ONO2 group, etc. in the side chain thereof. A fatty acid or its derivative or phosphate is used as a lubricant. The compd. that has the polar group can be used in conjunction with a binder such as a thermplastic or thermosetting resin in either case of using the same for the magnetic layer or back coating layer. The result of the measurement made for the degree of durability and powder dislodging after aging with respect to the magnetic tape obtained in the above-mentioned way reveals that the good result is obtainable only if the binder having the polar group is incorporated at least at >=20wt%.

Description

[Detailed description of the invention] The present invention relates to a magnetic recording medium.

More specifically, it relates to magnetic recording media, for which @Nameyomai's book was written in detail.

In general, magnetic recording media are formed by coating a magnetic layer on a non-magnetic support by kneading each FS4 lubricant with magnetic powder, a binder, etc. in order to impart lubricity. Alternatively, it is manufactured by coating a coating film such as a magnetic layer made of magnetic powder and a binder on a non-magnetic support, and further forming a conditioning layer thereon as a top coat. Of these, the top coat! ! Since this is carried out after the formation of the Iam film, the lubricant layer is maintained at a constant level, which is effective in maintaining running performance. However, depending on the type of binder that forms the coating film, the lubricant in the lubricant layer in step 7 migrates into the coating film and becomes lubricant. It obstructs the effect. As a result, the problem of stoppage during actual running may occur, or it may cause eruption of the magnetic head. Therefore, the present invention provides an all-at-once recording medium in which a clear layer is formed as a top coat. It is an object of the present invention to provide a magnetic recording medium which is improved from the above-mentioned drawbacks.

The magnetic recording medium according to the present invention has m! In the history of layer films, a tonal layer was provided as a top coat.

-01-1j[i, -8o, Ml group (however *MIFX
hydrogen atom or alkali metal), -C0
A compound having an inertial group such as 0M2 group (where M1 means a hydrogen atom or an alkali metal (1 means a hydrogen atom or a hydrocarbon bulk group), and the like is used.

As a lubricant in that @ hierarchy, Fjl Fatty or its v
Phosphorus ester is used for I4.

In this invention, as a compound having an inertial group used to form a coating film, as mentioned above, the four sets of molecular chains ζ-0kiilis, -8C) mountain 6 (however,
Ml means a hydrogen atom or alkali gold JIi)
h-coOM2 group (where 1M1 has an inertial group sandwiching a hydrogen atom or a group (R means a hydrogen atom or a bulk hydrocarbon group), etc.).

Among the polar groups mentioned above, as for alkali metals.

Examples include lithium, sodium, and potassium. The hydrocarbon group represented by R in -P(0)(OR)2 preferably means a linear or branched saturated or unsaturated aliphatic hydrogen group having 26 or less vertical atoms. do. Examples of such hydrocarbon groups include tricosyl group, tocosyl group, and coicosyl group.

Nonadecyl group, octadecyl group, hexadecyl group.

Saturated aliphatic hydrocarbons such as tridecyl group, kundecyl group, decyl group, nonyl crystal, octyl group, hexyl group, pentyl group, butyl crystal, t-butyl group, propyl group, inglovir group, ethyl group, methyl group, etc. Lycosenyl group, Heneiko Dainyl Kabu, nonatecenyl group, octadecenyl group, hexadecenyl group, trithecenyl group, cuntesenyl group, decenyl group, nonenyl group, octenyl group, hexenyl group.

Pentenyl! , butenyl group, tortoise-butenyl group, globenyl crystal, inglobenyl group, ethynyl group, and other unsaturated aliphatic hydrocarbon groups. Compounds having such inertial groups in their side chains include vinyl chloride-vinegar, etc. Vinyl rubinyl alcohol combination, vinyl chloride loop - vinyl rubinyl alcohol pionate A11 combination % vinyl chloride =
Vinyl monoacetate-vinyl pionate-vinyl alcohol copolymer, vinyl chloride-vinyl maleate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-vinyl maleate-vinyl alcohol copolymer, vinyl chloride-propion copolymer Vinyl malein moth vinyl-vinyl alcohol copolymer, polyester tree 11 &, polyurethane tree w
i or the above a8 * 0) 'D') -80
5M1 i/g, -000M2 Ji, -0N02
It k j Hi/or -P-(0L) It is modified with a hydrophilic group containing two ζ groups, and conjugates, etc.
Modification of t'mm can be carried out according to conventional methods. For example, the 1OH group that is present throughout the symbiotic resin, resin, etc. mentioned above.

(J'CH2CH2805M1, CICH2CO0
M2. C#C)12CH2(JNL)2.

by halides such as C1CH2P(OkL)2, in sm such as dimethylamide, dimethyl sulfoxide.

Modification can be carried out by reacting in the presence of a dehydrochlorination agent such as amines such as pyridine, picoline, and triethylamine, and epoxy compounds such as ethylene oxide and propylene oxide.

Furthermore, such modified compounds are: )10c)120
H280 black M1.1-1-1 Oel (2COO,)fo
ci(2C)12ONO2,)IOc)12P-(OR
)2 such as hydroxyl (ll*f, dimeterfor^7
Mid.

moths in a static medium such as dimethyl sulfoxide.

4. React with equimole of a isocyanate compound such as 4'-diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, etc., and the reaction product obtained is a copolymer as described above, -OH such as ** It is also possible to obtain it by reacting with a group.

In a compound having at least 1 m of inertia groups, in the case of a co-electronic polymer, the vinyl alcohol component unmodified with inertia groups is about L1.5 to 20
It is preferable to stack them in layers, and in the case of Otagi ml, the number of molecules per inertial group is about 200 to 5000.
In the present invention, a coating film formed as a magnetic layer on a non-magnetic support using a compound having a polar group as described above includes 1, for example, y -Fe
2O3, k'e504.

1- Fe2O3 and Fe,0. iron oxide in an intermediate oxidation state.

The iron oxide further contains 100 million or more metal elements (especially transition metal 7c wood), the iron oxide has a 9*a layer mainly composed of CO enemies or hydroxides, CrO
2. The surface of L'r02 was treated with oxides to form a Cr201 layer.

Metals such as Go and Ni, or Ni'e-Co alloy, F
e-N Karasu alloy, Fe-Co-Ni alloy, Co-N1-
P alloy, Co-Ni-Fe -8 alloy, k'e -N
i-Zn alloy, Fe-Mn-Zn alloy, Fe-G
Examples include ferromagnetic powders such as o-Ni-P alloys. In this case, abrasives such as aluminum oxide, chromium oxide, silicon oxide, etc., anti-fluorescent agents such as carphone black, and beak agents such as molybdenum disulfide, graphite, silicone oil, olive oil, butyl laurate, etc. Lecithin or the like can be added as a dispersant.

Friend, when using a compound having a polar group as mentioned above for the back coat layer, solid powders such as carbon black, graphite, kaolin, talc, *barium oxide, silicon dioxide 1% titanium oxide, etc. Used.

In this invention, when the compound having a polar group as described above is used in either the FMA layer or the back coat layer, it is used in combination with a binder such as a commonly used thermoplastic and/or thermosetting resin. Monkey-
1 In this case, these resins are approximately 2% of the binder ILJt.
A range of 0 to 80% by weight is preferred. Such resins include, for example, vinyl chloride-vinyl acetate copolymer, vinyl chloride-propion dense vinyl copolymer, and vinyl chloride-vinyl acetate vinyl alcohol copolymer.

tjltl, hinyl-probion, hinyl-vinyl alcohol copolymer, vinyl chloride-vinegared vinyl-malein copolymer, vinyl chloride-vinylidene chloride copolymer, ti
vinyl-acrylonitrile copolymer.

Acrylic acid ester-acrylonitrile copolymer.

Acrylic acid ester-vinyl chloride copolymer.

Methacrylic acid ester-vinylidene chloride combination.

Methacrylic acid ester-styrene/copolymer, vinylitine chloride-7crylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-
Acrylic copolymer, acrylonitrile-butadiene
Methacrylic acid copolymer.

Styrene-butadiene copolymer, formal resin.

Acetal lI fat, butyral resin, phenolic resin,
Examples include polyester resins, polyurethane resins, polyamide resins, IfC, base resins, urea-polmaldehyde resins, melamine resins, epoxy resins, alkaline resins, phenoxy resins, polyvinyl fluoride, and mixtures thereof.

Furthermore, usable bath additives include ketones #4, such as acetone, mether ether lactone, methyl isobutyl ketone, and cyclohexanone. Alcohols such as methanol and ethanol, esters such as methyl acetate, ethyl acetate, butyl acetate, and ethyl butyrate, 0% ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, glycol ethers such as dioxane, benzene, toluene, xylene, etc. B'flD group hydrocarbons such as aromatic hydrocarbons, hexane, and heptane are produced.

The benign paint-back coating paint obtained as described above can also be coated on a non-magnetic support by conventional coating methods such as the doctor blade method and the gravure coating method. ) Can be applied to desired thickness.

The non-conductive supports used are polyesters such as polyethylene terephthalate and polyolefins such as polypropylene.

Cellulose derivatives such as cellulose diacetate and cellulose triacetate, and polycarbonate.

Examples include poly(hinyl chloride), polyimide, boria, metal paper such as fulminium and copper.

In this invention, coating 111I! on a non-magnetic support as described above! After the formation of II! A threshold beak layer ρ is formed as a topcoat layer on top of the first layer. In this @ hierarchy, fatty acids or their derivatives and phosphoric acid esters are used. As per the mvJ acid used.

Examples include saturated fatty acids, unsaturated fatty acids, and 4a-type fatty acids having 8 to 22 carbon atoms.

Examples of such saturated fatty acid chestnuts include Capryl thorn, Kagrin #R, Laurin #R, Tridecyl nitrate, Kirsten #R
, Valmitic acid, stearin, isostearin, nonadecanoic acid, anoquinic acid, Behe/#! One example is Sudo. Also, as an unsaturated fatty acid.

Contains untesylenic acid, elaidic acid, oleic acid, etc. Furthermore, with respect to [@-type fatty acids, the aforementioned saturated fatty acids mean those in which unsaturated fatty acid residues are attached as open chains, and any such type may be used. I
The fatty acid derivatives used include N, fciI,
Amides and esters of IirEB acid are available. Furthermore, examples of the phosphoric acid ester include sodium oleyl phosphate, dipolyoxyethylene alkyl ether phosphoric acid #111 tripolyoxyethylene alkyl ether phosphoric acid, and the like.

Also, 11. as a solvent used to form the top coat layer. A bath agent that does not cause swelling of the binder contained in the underlying coating film is used, and among the above-mentioned bath agents, hydrocarbon-based bath agents are sometimes preferred.

In addition, in this invention, the amount of top coat.

Approximately 5 to 400 ~/straw 2. Preferably about 20 to 1
It is 20W//m2. The method for forming the top coat layer is not limited in any way, and any conventional coating method such as gravure coating or doctor grade may be used.

The magnetic recording medium according to the present invention having the above-mentioned structure shows no deterioration of its characteristics even after aging in a high temperature and low humidity environment, and its properties are clearly improved.

Hereinafter, this invention will be explained in more detail with reference to actual examples.

Example 1 ・ Group ・ □ Quantity (parts by weight) Co *
*ai! r-Fe20s 10
Ll binder (sodium lecithin sulfonate, 1 butyl laurate, 1 rice-based specimen having the above composition,
After mixing in a ball mill for 48 hours, it was subjected to f3 treatment using a 5μ fiber filter. An incyanate compound as a curing agent was added to this and applied onto a polyethylene terephthalate base film. After that, calendering treatment and heat treatment were performed. In this way, you can obtain the r of magnetic tape
Magnetic tapes were prepared by applying oleic acid at a ratio of 50/2 on the di injection layer. Examples 2 to 15 Except for using the compounds shown in Table 1, respectively.

Create a magnetic tape by straining it in the same way as Example 1. Next.

(Continued below with blank spaces and vacancies.) @ 1 Table Comparative Examples 1 to 5 Two-party tapes were prepared in the same manner as in Example 1, except that the compounds shown in Table 2 were used, respectively.

Table 2 Examples 1 to 15 prepared as described above and Comparative Example 1
The characteristics after aging of the nine magnetic tapes obtained in ~5 were measured, and the results are shown in Table 6.
・・・・・・・・・・・・Good Δ・・・・・・・・・Slightly good・・・・・・・・・Normal X・・・・・・・・・From the above results, the magnetic recording medium according to the present invention does not deteriorate in characteristics even when aged in high temperature and high humidity, as shown as a comparative example.

-f11 It has been revealed that in the case of using p/dr which does not have a polar group in the l1ill@ of the molecular chain, the properties deteriorate severely due to aging.

Example 16 Sodium sulfonate-rich urethane and urethane ([N-
Magnetic tapes were prepared in the same manner as in Example 1, except that the blending ratio with 2604J (manufactured by Nippon Polyurethane Industry Co., Ltd.) was changed.

The durability of these magnetic tapes after aging and the resistance to dust during actual running were measured, and the results are shown in Figure 1.

From this result, it was found that a binder having a polar group as described above cannot give good results in practical use if the binder has a weight of at least about 20% or more. ,implementation? Regarding the magnetic tapes obtained in step 11 and not provided with a top coat layer, their ** coefficients (voice d) were measured.
The former is Q, and the 200% wk ministry is 1610, which is 9. In addition,
*The friction coefficient is calculated from Euler's formula, and t
The measurements were carried out using a brass drum with a surface roughness of 18 at a tensile rate of 120 mm per minute with a load of 60 mm applied.

Historically, using these magnetic tapes, we have investigated the attenuation of the video S/N ratio during many days of driving in the heat.

This measurement uses a Betamax J-9 micro VTR, attaches a tliC experimental 5i tape to it, runs it 100 times, adds #j to the video S/N attenuation, and plots the result as @2 Take turns as shown in the figure.

As mentioned above and from the next chapter, the magnetic recording medium according to @Mei is extremely favorable in that, in combination with the friction coefficient, the amount of loss is in the range of 1 to 2 dB even after running 100 times. Nine results can be obtained. On the other hand, in the case of a magnetic tape that is not subjected to top coat processing, the attenuation of the video 87N becomes unsightly.

[Brief explanation of drawings]

Figure 1 is a graph showing the durability and degree of powder removal due to changes in the amount of reef group-containing compounds used in this invention, and Figure 2 is a graph showing changes in the amount of Y-SIN deterioration with respect to the number of running days. This is a graph showing. Agent: Ten Ueya, Yoshio Tsune, Toshiaki Sugiura□;・

Claims (1)

[Claims] 10H group, -805M group, in the side chain of the molecular structure (however, Ml is a hydrogen atom!! It also means an alkali metal). -C00M2 group (where Ml is a hydrogen atom or an alkali (however, R means a hydrogen atom or an alkali group) is applied onto a W1 film using a binder containing a hydrogen atom or an alkali group. A V & air rut medium characterized in that it is provided with a 10 m layer containing a conductor and an h-phosphate ester.