JPS59193971A - Magnetic coating - Google Patents

Abstract

PURPOSE:A magnetic coating for magnetic recording that contains a ring-opened epoxy compound in which the epoxy groups are opened with an amine to form hydroxyl groups, and a magnetic powder, thus showing high dispersibility, hydrolysis resistance, heat resistance and high film hardness. CONSTITUTION:The objective coating is obtained by mixing (A) (i) a ring-opened epoxy compound in which the epoxy groups are opened with an amine and/or a carboxylic acid to form hydroxyls and/or a polyurethane resultant from reaction between the component (i) and (ii) an isocyanate (preferably of 0.2-0.6NCO index) with (B) 20-2,000pts.wt., per 100pts.wt. of the polymer, of a magnetic powder and, when necessary, (C) a thermoplastic polyurethane and polyfunctional isocyanate. EFFECT:The resultant composition shows high compatibility with other resins.

Description

[Detailed description of the invention] The present invention relates to magnetic paint.

Recently, magnetic materials for magnetic recording are required to have increasingly high performance. For this purpose, it is important to improve the magnetic powder, but the binder used when applying the magnetic powder onto a support such as a tape is also an important factor.

Generally, when manufacturing magnetic tapes and the like, polyurethane resins are often used as surface coating resins, which provide a highly flexible and tough coating film. However, conventional polyurethane has a low ability to disperse magnetic powder, and to compensate for this, soybean lecithin or the like is used as a dispersant, but adverse effects such as bleeding occur during long-term use. Resins with good dispersibility such as menitrocellulose, polyvinyl butyral, and vinyl chloride/vinyl acetate/vinyl alcohol copolymers are also used in combination to improve such dispersibility; It had the disadvantage of being inferior in gender.

Various studies have been carried out with the aim of eliminating these drawbacks, such as (1) JP-A-51-44902 and (2) JP-A-51-51.
No. 1-44903, (3) No. 55-139634, (
4) No. 55-139636, (5) No. 5 f3-68
No. 925, (6) to (9) 56-101648 to 10
Magnetic recording bodies described in No. 1646 and the like are known.

However, for example, in (1) and (2), a urethane-modified epoxy resin containing no OH group is used, and (3) to (9)
), urethane resins with OH groups are used, but these are not modified with epoxy resins, and the number of OH groups is usually about 1 to 5, making it difficult to improve dispersibility. Although this has been achieved to some extent, it is still insufficient, and it also has disadvantages such as poor hydrolysis resistance and heat resistance.

Also, as OH group-containing polyurethane, 00 JP-A-57-0
No. 0529 uses trifunctional or higher functional hydroxy compounds such as glycerin, but if the NC010H ratio approaches 1 in order to increase the OH group concentration and molecular weight, gelation will occur, and this should be avoided. for NC0
When the 10H ratio is lowered, the molecular weight becomes smaller, and the resulting coating film has the drawback of having low strength.

Furthermore, in JP-A-57-158022, a polyurethane elastomer and an epoxy resin using a specific isocyanate are used, but there is still room for improvement in dispersibility.

An object of the present invention is to provide a magnetic paint in which the dispersibility of magnetic powder is significantly improved.

Another object of the present invention is to provide a magnetic coating material that has excellent hydrolysis resistance, heat resistance, film hardness, compatibility with other resins, etc.

(g) A ring-opening epoxy compound (a+) in which an epoxy group of an epoxy compound is ring-opened with an amine and/or a carboxylic acid to generate an OH group, and/or this ring-opening epoxy compound and an isocyanate compound are reacted. The present invention relates to a magnetic paint containing polyurethane (a2) obtained by the above method and magnetic powder.

In the present invention, the epoxy group of the epoxy compound is ring-opened with amines or carboxylic acids to add a large number of OH groups, thereby improving the dispersibility of the magnetic powder of the epoxy compound itself and creating a coating with excellent magnetic properties and durability. membrane can be provided.

The magnetic paint of the present invention is patent application filed in 1982-10 by the same applicant.
Similar, but not identical, to the magnetic paint described in No. 908. That is, the above-mentioned prior invention relates to a magnetic paint containing a modified polyurethane resin in which OH groups are generated by ring-opening the epoxy groups of an epoxy-modified polyurethane resin with amines and/or carboxylic acids, magnetic powder, and a polyfunctional isocyanate compound. This is related.

The structure of the present invention will be described in detail below.

In the present invention, various kinds of epoxy compounds can be used, such as Epicote 828834,! 0
01.1002.1008, +004.1007.10
Bisphenol-based epoxy resins such as 09 (manufactured by Yuka Shell Epoxy Co., Ltd.), Sumiepoxy ELA] 15.117.121.127.134 (manufactured by Sumitomo Chemical Co., Ltd.),
Epicote 152, +54. Sumi Epoxy ESCN
Examples include novolak epoxy resins such as 220LL, 22OL, 220F', and 220HH, and hydantoin epoxy resins such as ARACAST (manufactured by Ciba).

Examples of amines include primary amines such as ethylamine and n-butylamine; secondary amines such as diethylamine, dipropylamine, and dibutylamine;
Ethanolamine, N-methylethanolamine, N-
Alkanolamines such as butylethanolamine, jetanolamine, and dibrobanolamine, and carboxylic acids such as acetic acid, propionic acid, stearic acid, succinic acid, adipic acid, maleic acid, benzoic acid, phthalic acid, phenylacetic acid, and hydroxyl. Acetic acid (glycolic acid), lactic acid, 22-dimethylolpropionic acid, 9,10,12
．． 13. -tetraoxyoctadecanoic acid, acetic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, and the like. These amines and carboxylic acids can be used alone or in combination.

In the present invention, a ring-opened epoxy compound (al) is obtained by reacting the above epoxy compound with amines and/or carboxylic acids to open the epoxy group and generate an OH group. In the ring-opening reaction of the present invention, it is preferable to ring-open all the epoxy groups, but it is of course possible to leave a part of the epoxy groups. It is preferable to use the hacarboxylic acid in an amount of about 1-fold or less, preferably about 0.2 to 1-fold. The reaction is usually carried out at about 20 to 180°C, preferably about 100 to 150'C.
It is better to do it with

Further, polyurethane (az) is obtained by reacting the ring-opened epoxy compound obtained above with an isocyanate compound. In producing this polyurethane (az), it is optional to use a chain extender, and a separately prepared NCO-terminated prepolymer can also be used in place of the isocyanate compound.

The isocyanate compound used in the present invention may be any polyisocyanate known in polyurethane chemistry, such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IP
DI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), Z4-tolylene diisocyanate (2,4-TDI), 26-tolylene diisocyanate (26-TDI), 4,4-diphenylmethane diisocyanate (MDI), carpo Diimide modified MDI, polymethylene polyphenyl polyisocyanate (PAPI)
, ortho-toluidine diisocyanate (TODI), naphthylene diisocyanate (NDI), xylylene diisocyanate (MDI), lysine diisocyanate (L
DI), and one type or two or more types can be used.

Hyprene L-
100, L-800 (manufactured by Mitsui Nisso Urethane Co., Ltd.), Sofuranate UEX-50488 (manufactured by Toyo Tire & Rubber Industries, Ltd.), and the like.

Examples of the chain extender include di- to hexafunctional polyols with a molecular weight of 500 or less and diamines having a primary or secondary terminal amino group with a molecular weight of 500 or less. Suitable chain extenders include (a) ethylene glycol, dipropylene glycol, butanediol, 1,
Polyols (b) such as 6-hexanediol, glycerin, 1,4-cyclohexane dimetatool, and xylylene glycol Hiko; Diamines such as ethylenediamine, hexamethylenediamine, and cyclohexanediamine (
C) Alkanolamines (d) such as ethanolamine, jetanolamine, triethanolamine, etc.
Polyols with a molecular weight of 500 or less obtained by adding propylene oxide and/or ethylene oxide to hydroquinone, pyrogallol, 4,4'-isopropylidenediphenol, aniline, and the above polyols, diamines, and alkanolamines in any order. Examples include.

The polyurethane (az) of the present invention is synthesized using each of the above components, but at that time, the N'COIndex is usually 0.
9 or less, preferably in the range of about 0.2 to 0.6.

The magnetic paint of the present invention can be obtained by mixing the ring-opened epoxy compound (al) and/or polyurethane (az), magnetic powder, and, if necessary, a polyfunctional isocyanate compound. The NCOIndex of a magnetic paint is normally in the range of 0.9 to 5, but it is preferable to increase it even higher when considering the active hydrogen contained in the magnetic powder and other additives. Further, a thermoplastic polyurethane resin can also be blended into the magnetic coating material of the present invention.

As the polyfunctional isocyanate compound, a polyisocyanate having two or more functional groups can be used. Preferred specific examples include various isocyanate compounds that can be used in the production of the polyurethane (a2), and octafunctional inocyanate obtained from trimethylolpronoman and TD (trade name: Desmodur L1 Nishitoy 7. /
<Manufactured by Inil Co., Ltd.; Tsuronate L, manufactured by Nippon Polyurethane Co., Ltd.)
, Article 4 (trifunctional inocyanate manufactured by Inil Co., Ltd.)
Product name Desmodule N-75, Desmodule R1 Same H, etc.), Noipren L-100, Sofranate UEX-504
88, polymeric polyisocyanate (PPI), etc.

Various types of thermoplastic polyurethane materials can be used as the thermoplastic polyurethane resin.
28,268 (manufactured by Nippon Polyurethane Co., Ltd.), Nissan 5
702.5703.5711.5745 (BF・
Gutdrich), Nomandenox T-5201,
5205, 5102A (manufactured by Inu Nippon Ink Chemical Co., Ltd.), and the like.

Various types of magnetic powder can be used in the present invention, such as iron, chromium, dinochelium, cobalt, alloys thereof, oxides thereof, or modified products thereof. . Specific examples of oxides include γ-Fe 20B, ferrite, magnetite, CrO2, etc., and examples of trench-modified products include 1-Fe20B doped with cobalt, and bertolide compounds of Fe2O3 and Fe3O4 doped with cobalt. can be mentioned. The magnetic powder content is 1 polymer
Preferably, the ratio is about 50 to 2000 ω parts to 000+ parts.

In the present invention, vinyl chloride resins, vinylidene chloride resins, vinyl chloride/vinyl acetate/vinyl alcohol copolymer resins (manufactured by UCC, VAGH, etc.), nitrocellulose, polyvinyl butyral resins, polyester resins, etc. Resins such as resin, alkyd resin, epoxy resin, acrylonitrile-butadiene rubber, etc. can be blended.

In the present invention, dispersants, lubricants, abrasives,
Additives such as antistatic agents may also be added.

The magnetic coating material of the present invention can be produced by mixing the above-mentioned components by various methods. For example, it is preferable to use a mixer, roll mill, ball mill, sand mill, high-speed impeller, etc. In particular, it is preferable to add the polyfunctional isocyanate compound after it has been sufficiently dispersed, as this will extend the pot life. Further, it is preferable to use a solvent during the ring-opening reaction of the epoxy compound of the present invention, during the production of polyurethane (a2), and during the production of the above-mentioned magnetic paint. Suitable solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone,
Ketones such as cyclohexanone, benzene, toluene,
Examples include aromatic hydrocarbons such as xylene, esters such as ethyl acetate and butyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, 3-methoxybutyl acetate, ethylene glycol diacetate, dimethylformamide, and dimethylacetamide.

The magnetic coating material of the present invention can be applied to supports in various forms such as tapes, sheets, cards, disks, drums, etc. according to known methods.

Examples and test examples will be described below. In addition, parts and % simply indicate weight, parts, and weight %.

Example 1 21 equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube
38Of, cyclohexanone 885 F, and jetanolamine 2102 were placed in a separable flask, and reacted in a nitrogen stream at 120°C for 3 hours to reduce the solid content to 40%. , viscosity 100 cps (25°C), OH group concentration], a ring-opened epoxy resin solution α) of Qmeq/ii' polymer was obtained.

1-Fe20B (10
0 parts), thermoplastic polyurethane resin (Nistan 570g
), cyclohexanone (65 parts), and methyl ethyl ketone (88 parts) were added, and after kneading in a ball mill for 24 hours, Coronate L (8 parts) was added and kneading was further carried out for 2 hours to obtain the magnetic paint of the present invention.

Example 2 Epicor)-152 (EE=176)”376.6
The same procedure as in Example 1 was carried out using gel, jetanolamine 224.75', and cyclohexanone 9027, and the solid content was 40%, the viscosity was 80 cps (25°C), and the OH group concentration was 5.
A ring-opened epoxy resin solution (II) of 0 m e q/17' polymer was obtained.

Thereafter, a magnetic coating material of the present invention was obtained in the same manner as in Example 1 using this solution (11).

Example 3 Ring-opened epoxy resin solution of Example 1 (1) 8 o o
y, MDI (12,!M), cyclohexanone (+9f
) was heated and reacted at 80°C for 3 hours under a nitrogen stream, resulting in a solid content of 40%, a viscosity of 1080 cps (25°C), and an OH
Base concentration 0. (32 meq/f Polyurethane solution (1) of polymer was obtained.

Using this solution (g), a magnetic coating material of the present invention was obtained in the same manner as in Example 1.

Comparative Example 1 A magnetic paint was obtained in the same manner as in Example 1, except that a 40% cyclohexanone solution of Epicoat 1001 was used instead of solution (I).

Comparative Example 2 A magnetic paint was obtained in the same manner as in Example 1, except that a 40% cyclohexanone solution of nitrocellulose was used instead of solution (I).

Test Example 1 The obtained magnetic paint was applied onto a polyester film using a doctor blade, dried at room temperature for 2 hours, and then heated and dried in an oven at 80°C for 24 hours to obtain a magnetic coating film.

In order to examine the dispersibility of the magnetic coating, the surface gloss of the magnetic coating was measured using a gloss meter (Toyo Seiki S-60). The better the dispersibility, the better the gloss.

In addition, in order to examine the strength of the magnetic coating film, the coating film was heated at 70°C19
After being placed in a constant temperature and humidity chamber adjusted to 5% RH for two weeks and humidified, a one-stroke test was performed using a pencil with a hardness of 2H.

The evaluation was as follows: ◎ No scratches, △ Scratches, x Peeling. The results are shown in Table 1.

Chapter 1 Table (that's all)

Claims (3)

[Claims] (1) (g) A ring-opening epoxy compound (al) in which the epoxy group of the epoxy compound is ring-opened with amines and/or carboxylic acids to generate an OH group, and/or this ring-opening epoxy compound is reacted with an isocyanate compound. and (a) a magnetic paint containing magnetic powder. (2) The magnetic paint according to claim 1, further comprising a thermoplastic polyurethane resin. (3) The magnetic paint according to claim 1 or 2, further containing a polyfunctional isocyanate compound.