JPS60252670A - Magnetic paint composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition having improved dispersibility and excellent resistance to hydrolysis, by opening the epoxy ring of a novolac-type epoxy-modified polyurethane resin to obtain a specific modified polyurethane resin, and using an organic solvent solution of the resin and magnetic powder as main components. CONSTITUTION:The objective composition is composed mainly of (A) an organic solvent solution of a modified polyurethane resin having >=3 functional groups and containing >=0.1meq/g of OH group in the molecular chain, and obtained by the urethanization with a novolac-type epoxy resin wherein the epoxy resin component is preferably represented by the formula [R' is H or CH3; average of n is >=1; 1<(average of m+1)<=2], or a polyfunctional isocyanate compound, etc., and opening the ring with an amine, carboxylic acid and/or phenolic compound to generate OH groups and (B) magnetic powder. EFFECT:Excellent adhesivity to the base film.

Description

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

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 to 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 resins for surface coatings, which are highly flexible and provide strong coatings. 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. To improve such dispersion ability, nitrocellulose, polyvinyl butyral,
Resins with good dispersibility such as vinyl chloride/vinyl acetate/vinyl alcohol copolymers have also been used in combination, but this has the disadvantage of poor abrasion resistance and flexibility.

Various studies have been carried out with the aim of solving these drawbacks, such as (1) Japanese Patent Application Laid-Open No. 5-44902, (2)
No. 51-44903, (3) No. 55-139634, (4) No. 55-189636, (5) No. 56-68
No. 925, (6) to (9) 56-101643 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 011 group is used, and in (3)
In ~(9), urethane 10K (fat) having OH groups is used, but these are not modified with epoxy resins, and the number of 011 groups is usually about 1 to 5. Although improvement in dispersibility has been achieved to some extent, it is still insufficient, and also has drawbacks such as poor hydrolysis resistance and heat resistance.

In addition, as a polyol component of polyurethane containing 011 groups, (10) JP-A No. 57-60529 describes
There are some that use hydroxy compounds that are more than functional,
In order to increase the concentration and molecular weight of 011 groups using this method, NGO1
If the 0H ratio is brought close to 1, gelation will occur, and if the N CO/OI+ ratio is lowered to avoid this, the molecular weight will become smaller, which has the disadvantage that the resulting coating film will have lower strength. Furthermore, (11) Unexamined Japanese Patent Publication No. 57-158
Although polyurethane elastomer and epoxy resin using a specific incyanate are used in 022, 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 paint with excellent hydrolysis resistance and adhesion to a base film.

In the present invention, the epoxy group of a novolak-based epoxy-modified polyurethane resin is ring-opened with at least one of amines, carboxylic acids, and 7-ethyls to form an 0-I group, and an OH group is added in the molecular chain. The present invention relates to a magnetic coating composition containing as main components an organic solvent solution of a modified polyurethane resin containing 0.1m eLl/g or more and having a functional group number of 3 or more and magnetic powder.

In the present invention, the OH group in the molecular chain is O, imeq/g.
By using an epoxy-modified polyurethane resin that has two functional groups (number of OH groups in the molecule) of three or more, a synergistic effect between the presence of a large number of OH groups and the presence of the bisphenol skeleton of the epoxy resin can be achieved. As a result, not only excellent dispersibility of the magnetic powder was improved, but also significant improvements were achieved in hydrolysis resistance, adhesion to the base film, etc.

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

The modified polyurethane resin of the present invention having three or more functional groups containing OH groups in its molecular chain is subjected to a urethanization reaction using a polyol, an isocyanate compound, and a heptadoric epoxy resin by a known method, and then amines, carboxyl, etc. It can be obtained by reacting with at least one of acids and phenols. In this case it is also optional to use chain extenders. The content of OH groups in the modified polyurethane resin is preferably O,1, meq/g or more, and the number of functional groups is 3.
More preferably 6 or more, especially 6 or more.

In the present invention, various polyester polyols, polyether polyols, and other polyols can be used as the polyol. Specific examples of polyester polyols include polyethylene adipate polyol,
Adipate polyols such as polybutylene anovate polyol and polyethylene propylene assortate polyol, terephthalic acid polyols (e.g., Toyobo Co., Ltd., product names Vylon RUX, Vylon RV-2001), polycaprolactone polyols (e.g., Gycel Chemical, products) Praxel 212, Praxel 220), etc. can be exemplified.

Specific examples of polyether polyols include polyoxyethylene glycol, polyoxypropylene polyol, polyoxyethylene polyoxybrobylene polyol, polyoxytetramethylene polyol, and the like.

In addition, other polyols include polycarbonate polyol (e.g., Bayer AG, West Germany, trade name Desmoreen 2020E), polybutadiene polyol (e.g., Nippon Soda, trade name G-1000, G-2000, G-300).
0, Idemitsu Petrochemical, trade name Poly bd R-45)
IT), polypentadiene polyol, castor oil polyol, and the like. These polyols are 1
A species or two or more species can be used simultaneously.

Various types of incyanate compounds are exemplified, such as nophenylmethane diisocyanate (M
DI), 2,4-tolylenequizocyane) (2,4
-TDI), 2,6-dolylenenoisocyanate (2,
6-Tl1l), tolidine diisocyanate) (TOD
I), xylylene diisocyanate (XI), naphthylene diisocyanate (NDI), inphorone diisocyanate (If'DI), hexamethylene diisocyanate (IIDI), dicyclohexylmethane diisocyanate) (I( Examples include diisocyanates such as Ml)r), lysine diisocyanate (Ll)I), and polyisocyanates such as carposiimide-modified MDI, and these may be used alone or in combination of two or more.

In the present invention, various 7-bofutsu epoxy resins can be used as the epoxy compound, such as Ebihuto 152.154, Sumiepoxy ELPN-180, E
Phenol Novofook epoxy resin such as SPN-180, Sumiepoxy ESCN 220L, 220F.

E manufactured by Nippon Kayaku Co., Ltd. such as 220HH1ESMN-220L
Examples include cresol/borac epoxy resins such as OCN-102, 103, and 104.

In particular, epoxy resins having an epoxy group in the molecular chain represented by the following formula are preferably used.

(R' is hydrogen or a methyl group, ■ indicates a number of 1 or more on average, and i<(average value of +n+1)≦2) The epoxy group of the above epoxy group-modified polyurethane resin is further added to amines, carboxylic acids, etc. The ring is opened with at least one kind of M and phenols, and the amines used in this case include, for example, primary amines such as ethylamine and n-butylamine, and secondary amines such as diethylamine, cypressylamine, and dibutylamine. alkafuramines such as ethanolamine, N-methylethanolamine, N-butylethanolamine, jetanolamine, dibrobanolamine, and carboxylic acids such as acetic acid, propionic acid,
Stearic acid, succinic acid, adipic acid, maleic acid, benzoic acid, 7-talic acid, phenylacetic acid, hydroxyacetic acid (glycolic acid), lactic acid, 2,2-thumethyrolpropionic acid, 9,10.12.13-tetra Oxyoctadecanoic acid, acetic anhydride 1. Succinic anhydride, maleic anhydride, 7-talic anhydride, etc. can be mentioned. Moreover, as the 7 ethers, phenol, cresol, etc. are preferable. , these amines, carboxylic acids and 7 ethers can be used alone or in combination.

As a chain extender, for example, 2 to 6 with a molecular weight of 500 or less
Functional polyol and primary or secondary having a molecular weight of 500 or less
Examples include diamines having a terminal amino group of 100%. Suitable chain extenders include, for example, ethylene glycol, diethylene glycol, propylene glycol, nopropylene glycol, butanol, hexanediol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, 1,4-cyclohexanediol, 1.4 -Polyols such as cyclohexanemethanol and xylylene glycol (1)) Diamines such as hydrazine, ethylene oxide, tetramethylenezamine, hexamethylenezamine, ■, 4-cyclohexanoamine (c) Ethanolamine, noethanol Alkanolamines such as amines and trif-7-alamine (d) Hydroquinone, pyrogallol, 4,4-impropylidene di-7-yl, aniline, and the above polyols, diamines, alkali/ruaminos, propylene oxide and Examples include polyols having a molecular weight of 500 or less obtained by adding/or ethylene oxide in any order.

Epoxy-modified polyurethane resin is synthesized using each of the above components, and at that time, the NCOIndex is usually about 0.
7-1.2. Preferably, the reaction is carried out within a range of about 0.9 to 1.1.

In the ring-opening reaction of the present invention, it is preferable to open all the epoxy groups, but of course 1/11 parts of the epoxy groups may remain, and usually about 1 part of the amines and/or carboxylic acids is added to the epoxy group. Less than double equivalent, preferably about 0
．． It is better to use 2 to 1 equivalent. The reaction is usually 20~
] 80'C1 Preferably, it is carried out at about 100 to 1.50°C. In this case, it is possible to use known catalysts for curing epoxy resins, and tertiary amine and imiguzole catalysts are particularly effective.

The above ring-opened modified polyurethane resin of the present invention has a large number of 0-squares in its molecule and has extremely good dispersibility of magnetic powder. The number of 011 groups is usually 3 or more, preferably 2, and generally 6.
It is preferable to have up to 30, particularly preferably 10 to 20, 0■ groups.

The magnetic coating composition of the present invention can be obtained by mixing the above-mentioned modified polyurethane resin containing hydroxyl groups, magnetic powder, and, if necessary, a polyfunctional incyanate compound. The NCOIndex for magnetic paint is usually 0.
A range of 9 to 1.5 is appropriate, but a higher value is preferable when considering the active hydrogen contained in the magnetic powder and other additives. In the present invention, the modified polyurethane resin can be manufactured by a known method, such as the Funschott method or the prepolymer method. Urethane catalysts can also be used. The concentration of hydroxyl groups in the modified polyurethane resin of the present invention is preferably 0, ], +neq/
g or more.

As the polyfunctional incyanate compound, a polyisocyanate having two or more functional groups can be used. Preferred specific examples include the above-mentioned various incyanate compounds and trifunctional incyanate (trade name Desmodur) obtained from trimethylolpropane and TDI.
Manufactured by Bayer, West Germany; Coronet H-1 Nippon Polyurethane! Similarly, trifunctional incyanate manufactured by Bayer (trade name Desmonyl N-75, same R1)
”, etc.), Hi-Brain L, -100, So7 Rannate [I
EX-504SS.

Polymethylene polyphenylinocyanate (FAI'l)
), polymer link polyisocyanate (PPI), and the like.

Various types of magnetic powder can be used in the present invention, including iron, chromium, nickel, cobalt, alloys thereof, oxides thereof, and modified products thereof. Specific examples of oxides include γ-Fe2O3, 7-elite, magnetite, CrO2, etc., and examples of modified products include cobalt-doped γ-Fe20, cobalt-doped Fe, O-, and Fe3O4. Examples include bertolide compounds and the like. It is also possible to use magnetic powders having various surface areas, and particularly when using ferromagnetic powders with a specific surface area of 25 m27 g or more determined from the amount of nitrogen adsorbed by the BET method, excellent magnetic properties can be obtained. The amount of magnetic powder blended is preferably about 50 to 2000 parts by weight per 100 parts by weight of the modified polyurethane resin.

In the present invention, thermoplastic polyurethane resins, vinyl chloride resins, vinylidene chloride resins, PVC/vinyl acetate/vinyl alcohol copolymer resins (UCC
Resins such as nitro cellulose, polyvinyl butyral resin, polyester resin, alkyd resin, epoxy resin, and acrylonitrile-butadiene rubber can be blended.

Various types of thermoplastic polyurethane resins can be used as the thermoplastic polyurethane resin, but a specific example is Paraprene 228.
．． 26S (manufactured by Nippon Polyurethane Co., Ltd.), Nissan 5702
．． 5703.5711.5715 (manufactured by BF Gutdrich), Pandex T-5201, 5205,
5102A (manufactured by Dainippon Ink Chemical Co., Ltd.) and the like. Furthermore, in the present invention, normally used as necessary,
Additives such as dispersants, lubricants, abrasives, antistatic agents, etc. can be added.

The magnetic paint of the present invention can be obtained by mixing the above-mentioned components by various known methods, and for example, a mixer, roll mill, ball mill, sand mill, high-speed impeller, etc. can be used. In particular, it is preferable to add the polyfunctional incyanate compound after it has been sufficiently dispersed, as this will extend the pot life. In addition, it is preferable to use an organic solvent when producing the modified polyurethane resin of the present invention, when producing the above-mentioned magnetic coating composition, and suitable solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. , aromatic hydrocarbons such as benzene, toluene, and xylene, esters such as ethyl acetate and butyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, 3-methoxybutyl acetate, ethylene glycol diacetate, dimethylformamide, dimethylacetamide, etc. can be mentioned.

The magnetic paint of the present invention can be applied to supports in various forms such as tapes, sheets, cards, disks, and drums. The support usually has a thickness of about 5-50μ, preferably about 10-50μ.
The diameter is preferably about 40μ, and suitable materials include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose acetate, polycarbonate, polyamide, polyimide, polyamideimide, and the like. Various methods can be used to apply the magnetic paint onto the support, such as impregnation coating, air doctor coating, air knife coating, flade coating, reverse roll coating, gravure coating, cast coating, and spray coating. . After coating, the magnetic powder may be subjected to treatment to orient it if necessary, or dried if it contains a general organic solvent. The drying temperature is usually about 20 to 100°C, and the drying time is about 5 minutes or more, preferably about 5 minutes to 24 hours. After drying, it is preferable to cure at 50 to 140° C. for about 1 minute to 2 hours. Furthermore, if necessary, a surface smoothing treatment can be performed before or after curing, or it can be cut into a desired shape.

EXAMPLES The present invention will be described in detail below with reference to Examples, Comparative Examples, and Test Examples. Note that parts and % simply indicate parts by weight and % by weight.

Example 1 33.0 g of diphenylmethane noisocyanate (801) was placed in a 1 liter separable 7 rasf equipped with a thermometer, stirrer, nitrogen gas inlet pipe and condenser.

Bion RV200L (molecular weight 2000) 88.0g,
centre? 9 Cell 220 (molecular weight 2000) 88.0g
, ESCN-22OL (9 t-L equivalent molecular weight 130
0, epoxy equivalent weight 213) 18.3g.

Weighed out 3.2 g of 1.6-hexanediol and 559 g of cyclohexanone, and heated them at about 8°C in a dry nitrogen stream.
2250c+ based on NGO group by TR spectrum at
The reaction is allowed to proceed until no absorption of n-' is detected, yielding a viscous solution. Add 9.08 g of jetanolamine to this solution and heat at 140°C for 5 hours to combine the epoxy groups and N I-
One reaction is carried out.

The solution thus obtained had a solid content of 30% and a viscosity of 30%.
At 0 mPa-5 (25°C), the calculated OH group concentration of the polymer was 1.08+neq/g.

100 parts by weight of the above modified polyurethane solution, 1 part of magnetic powder
00 methyl ethyl ketone 100 was placed in a ball mill and kneaded for 72 hours to obtain a magnetic coating composition. Pferric is used as the magnetic powder.

2674 (7 Isa I joined Magnetics!) was used.

Example 2 M D I 33.1. g Byron RV 2 '00 L 122.8g Plaxel 220 55. '28 ESCN 22 OL 14.4g cyclohexane 559Fi was reacted at 80°C for 2 hours in the same apparatus as in Example 1], 3.3g of 6-hexanediol was added, and the TR spectrum was further heated at 80°C. The reaction is allowed to proceed until absorption based on NCO groups is no longer observed, yielding a viscous solution. Add 4.9 g of hydroxyacetic acid to this solution, +40
'C for 14 hours.

The obtained solution had a solid content of 30% and a viscosity of 350 mPa-5.
(25℃), the OH group concentration of the polymer is 0.54meq
/g.

A magnetic paint was prepared in the same manner as in Example 1 except that this modified polyurethane solution was used.

Example 3 M D I , 32.78 Byron RUX ]Q4.4Fi (molecular weight 2000) Niboran 4070 87.0FI (molecular weight 2000)
E S CN2201. 9,1° diethylene glycol 2.9g cyclohexanone 558Fi Reacted in the same manner as in Example 1 to obtain an epoxy-modified polyurethane solution, and further added 3.1g of propionic acid and heated at 140°C.
Allow to react for 14 hours. The resulting solution had a solid content of 30%,
Viscosity is 560mPa-5 (25°C), OH group concentration is 0
．． It was 18 meq/pi.

A magnetic paint was prepared in the same manner as in Example 1 except that this modified polyurethane solution was used.

Comparative Example 1 M'DI 33.4g H4a NRUX 106.8g Nituboran 4070 89. Og E S CN2201. 4.6 g 1,6-hexanediol 3.8 g cyclohexanone 558° A reaction was carried out in the same manner as in Example 1 to obtain an epoxy-modified polyurethane. Further, 1.6 g of propionic acid was added and the mixture was reacted at 140° C. for 14 hours. The resulting solution had a solid content of 30%, a viscosity of 610 mPa = 5 (25°C), and an OH group concentration of 0.09 meq/g.

Comparative Example 2 A magnetic coating material was prepared in the same manner as in Example 1, except that jetanolamine was added to the epoxy-modified polyurethane solution and the heating reaction was not carried out.

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 at 100°C.
A magnetic coating film was obtained by heating and drying in an oven for 20 hours.

In order to examine the dispersibility of the magnetic coating, the surface gloss of the magnetic coating was measured using a gloss meter (TC-1080, manufactured by Tokyo Juishiki Co., Ltd.). The better the dispersibility, the better the gloss.

The results are shown in Table 1.

Claims (3)

[Claims] (1) The epoxy group of a 7-borac type epoxy-modified polyurethane resin is ring-opened with at least one of amines, carboxylic acids, and phenols to generate OH groups, Q, 1 meq/g of OH groups in the molecular chain. A magnetic coating composition containing as main components an organic solvent solution of a modified polyurethane resin containing three or more functional groups and magnetic powder. (2) The epoxy resin component is a compound represented by the formula (R' is hydrogen or a methyl group, 11 represents a number on average of 1 or more, and l<(average value of m+1)≦2). A composition according to scope 1. (3) The composition according to claim 1, which contains a polyfunctional incyanate compound.