JPH04286716A - Flexible magnetic disk - Google Patents

Abstract

PURPOSE:To provide the flexible magnetic disk which is imparted with excellent magnetic recording characteristics and particularly high-density magnetic recording characteristics by improving the dispersibility and dispersion stability of ferromagnetic powder of a magnetic coating material, thereby improving the surface smoothness of the magnetic coating material. CONSTITUTION:The magnetic coating material of the flexible magnetic disk constituted by providing the coated film of the magnetic coating material contg. the ferromagnetic powder on a nonmagnetic base contains polyisocyanate having average 2.5 to 6 pieces of isocyanate groups within A molecule and an addition compd. derived from a compd. reactive with the isocyanate groups.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to flexible magnetic disks, and more specifically, it improves the dispersibility and dispersion stability of ferromagnetic powder in magnetic coatings, improves the surface smoothness of magnetic coatings, and provides excellent The present invention relates to a flexible magnetic disk with magnetic recording properties, particularly high-density magnetic recording properties.

0002

[Prior Art] In recent years, high-density recording on flexible magnetic disks has been studied, and as ferromagnetic powder, fine particle size Co-coated γ has been studied.
- Iron oxide, metal magnetic powder with fine particle size and high coercive force, hexagonal barium ferrite powder with hexagonal plate shape and fine particle size, etc. are attracting attention. However, when making paints from these ferromagnetic powders, the quality of dispersion is always a problem, and a satisfactory solution has not yet been reached.

For example, plate-shaped hexagonal barium ferrite powder has an axis of easy magnetization in the direction perpendicular to the plate surface, so barium ferrite particles in the paint come into contact with each other plate-shaped surfaces, forming extremely strong aggregates. . Further, since metal magnetic powder has a larger magnetic moment than oxide-based magnetic powder, the powders strongly attract each other and form extremely strong aggregates in the paint.

[0004] Binders for magnetic powder include vinyl chloride-vinyl acetate copolymers, cellulose resins, polyurethane resins, polyester resins, polyester-polyurethane resins, polycarbonates, polyurethane resins, and polyvinyl butyral resins. In recent years, especially from the viewpoint of dispersibility and filling properties of magnetic powder, polar groups such as sulfonic acid groups, sulfuric acid ester groups, phosphoric acid ester groups, phosphonic acid groups, and carboxylic acid groups have been added to the above polymers. Resins attached to the backbone or side chains of are now widely used. However, since the cohesive force of the metal magnetic powder and hexagonal barium ferrite powder is extremely strong, it is difficult to finely disperse the aggregates with the binder.
Only a paint with insufficient dispersibility is obtained, and a satisfactory magnetic disk cannot be obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to improve the dispersibility and dispersion stability of ferromagnetic powder in a magnetic coating, thereby achieving even higher surface smoothness and higher density of the magnetic coating.
The object of the present invention is to provide a flexible magnetic disk having excellent magnetic recording properties, particularly high-density magnetic recording properties.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present inventors have conducted extensive research and found that an average of 2
．． When a magnetic paint contains an addition compound derived from a polyisocyanate having 5 to 6 isocyanate groups and a compound reactive with the isocyanate groups, the above-mentioned agglomeration of the ferromagnetic powder is loosened during the dispersion treatment of the magnetic powder. Furthermore, the loosened magnetic powder is prevented from re-agglomerating in the paint (
For example, even if the paint is left to stand for a long time and then formed into a film, there are almost no "bumps" due to re-agglomeration).
The present invention was achieved based on the discovery that the surface smoothness of a magnetic coating film can be significantly improved.

That is, the present invention provides a flexible magnetic disk comprising a coating film of a magnetic paint containing ferromagnetic powder on a non-magnetic support, wherein the magnetic paint has (A) an average particle size within the molecule. A flexible magnetic disk characterized by containing an addition compound derived from a polyisocyanate having 2.5 to 6 isocyanate groups and a compound reactive with the isocyanate groups.

In the present invention, the nonmagnetic support is not particularly limited, and any commonly used nonmagnetic support can be used. Examples of non-magnetic supports include polyethylene terephthalate, polyethylene-2,6-naphthalate, polyethylene, polypropylene, polycarbonate, polyamide,
Examples include films of various synthetic resins such as polyamideimide, polyimide, polysulfone, and polyethersulfone, and metal foils such as aluminum foil and stainless steel foil.

In the present invention, the ferromagnetic powder is not particularly limited, and commonly used powders can be used, but in particular, Co-coated gamma ferrite powder, Fe-based metal powder, hexagonal barium ferrite powder, etc. etc. are preferred. Furthermore, this Co-adhered gamma ferrite powder has a saturation magnetization greater than 65 emu/g and a specific surface area of 20 m2.
/g and a coercive force larger than 500 Oe (Oersted) is preferable. The metal powder mainly composed of Fe preferably has a saturation magnetization of more than 100 emu/g, a specific surface area of more than 30 m2/g, and a coercive force in the range of 700 to 2000 Oe. In addition, this hexagonal barium ferrite powder has a saturation magnetization larger than 50 emu/g and a specific surface area of 25 m2.
/g, coercive force is 200-2000 Oe
Preferably, it falls within this range.

[0010] In the present invention, the magnetic paint is prepared by mixing and dispersing the ferromagnetic powder with a binder, etc., and any known method or method accumulated in the art can be used as the dispersion method.

In the present invention, one component of the binder is the addition compound (A), that is, an average of 2
．． It is characterized by using a polyisocyanate having 5 to 6 isocyanate groups and an addition compound derived from a compound reactive with the isocyanate groups.

[0012] Examples of this polyisocyanate include:

[0013]

[Chemical formula 1]

[0014]

[Case 2]

[0015]

[Chemical formula 3]

[0016]

[C4]

[0017]

[C5]

[0018]

[C6]

[0019]

[C7]

[0020]

[Image Omitted] and the like can be preferably mentioned. These exemplified compounds have an isocyanuric acid structure obtained from a diisocyanate by a biuret reaction, or produced by ring formation of a diisocyanate.

The compound to be reacted with this polyisocyanate is a group reactive with NCO groups (for example, -OH, -NH
2, -NHR (R; alkyl group having 1 to 4 carbon atoms), etc.)
It is a compound having 1 to 3 carbon atoms, for example, 8 to 30 carbon atoms.
aliphatic or alicyclic monoalcohol (hydrogen atoms may be partially substituted with halogen atoms or aryl groups), at least one -O- group and/or -COO- group in the molecule aliphatic, alicyclic or aromatic monoalcohols (hydrogen atoms may be partially substituted with halogen atoms), fatty acids having 2 to 3 of the above reactive groups and a molecular weight of 3000 or less group, alicyclic or aromatic compound (-O-, -COO-, -CONH-
group, -S- group, -SO2- group, etc.)
, a compound having a Tzelevitinoff active hydrogen atom and at least one nitrogen atom-containing basic group.

The addition compound (A) used in the present invention is:
For example, Japanese Patent Publication No. 2-19844, Japanese Patent Application Publication No. 1-135
526, Japanese Patent Application Laid-Open No. 1-139132, etc., together with the manufacturing method thereof.

This addition compound (A) has a strong affinity for the surface of the ferromagnetic powder because the -NCO- group component locally localized in the molecule significantly reduces the dispersion of the ferromagnetic powder in the magnetic paint. In addition, the large number of side chain groups extending radially from the polyisocyanate skeleton has the effect of preventing the reaggregation of the ferromagnetic powder once dispersed.

The amount of addition compound (A) used is 1 ferromagnetic powder.
00 parts by weight, 0.1 to 30 parts by weight, further 0.5 to 2 parts by weight
Preferably it is 5 parts by weight, especially 1 to 25 parts by weight. If this amount is too small, this effect will not be expressed. On the other hand, if this amount is too large, there will be no room for adding other types of additives.

In the present invention, it is preferable to use a resin (B) containing sulfobetaine together with the addition compound (A). Thereby, the effects of the additional compound (A) can be further enhanced.

The resin (B) containing sulfobetaine may be any resin as long as it contains sulfobetaine in its molecule, and examples of such resins include urethane resins, polyester resins, vinyl chloride copolymers, etc. , vinylidene chloride copolymers, acrylic resins, butadiene-acrylonitrile copolymers, styrene-butadiene copolymers, and the like. The specific manufacturing method of these resins is not limited in any way by the present invention, and they may be manufactured according to known methods. For example, JP-A-2-5
Examples include those described in Japanese Patent No. 6719.

Here, the structure of sulfobetaine is expressed by the following formula (
9,10)

[0028]

[Chemical formula 9]

[0029]

It is represented by [Chemical formula 10] etc. X in the above formula represents an alkylene group. In order to exhibit the above-mentioned effects, preferably an alkylene group having 2 to 10 carbon atoms, particularly preferably an unsubstituted alkylene group, is selected. Moreover, R in the formula represents an alkyl group having 1 to 4 carbon atoms. Furthermore, at least one Z in the formula represents an R group or a chemical bond bonded to the main chain or side chain of the resin molecule.

The molecular weight of the sulfobetaine-containing resin is preferably 5,000 or more, more preferably 10,000 or more. Also, this molecular weight is determined from the viscoelastic behavior of the magnetic paint to be 200,
000 or less is preferable. The content of sulfobetaine is preferably at least 1 x 10-6 equivalent/g (resin), and more preferably 1 x 10-6 to 1 x 10-2 equivalent/g from the viewpoint of dispersing the magnetic powder and preventing re-agglomeration. g (resin), particularly preferably in the range of 1×10 −5 to 1×10 −2 equivalent/g (resin).

The amount of the sulfobetaine-containing resin used is 0.1 to 50 parts by weight, and more preferably 0.1 to 50 parts by weight, per 100 parts by weight of ferromagnetic powder.
It is preferably 5 to 40 parts by weight, particularly 1 to 30 parts by weight. The sulfobetaine-containing resin is selected by considering not only the weight ratio but also the amount of sulfobetaine in the resin.
The amount of sulfobetaine per 00g is 1x10-6 to 1x
10-2 equivalent/100g (magnetic powder), further 2 x 10-
6 to 1×10-2 equivalent/100g (magnetic powder), especially 5×
It is preferable to set it as 10<-6>-5*10<-3> equivalent/100g (magnetic powder).

The magnetic paint in the present invention includes the above-mentioned ferromagnetic powder, addition compound (A), and sulfobetaine-containing resin (
In addition to B), conventionally known or used components may be included. For example, binders such as thermoplastic resins, thermosetting resins, and reactive resins, abrasives, antistatic agents, reinforcing agents, dispersants, lubricants, and the like can be contained singly or in combination.

This thermoplastic resin has a softening temperature of 15
0℃ or less, average molecular weight 10,000-300,000
, with a degree of polymerization of about 50 to 2,000, such as vinyl chloride/vinyl acetate copolymer, vinyl chloride/vinylidene chloride copolymer, vinyl chloride/acrylonitrile copolymer, acrylic ester/acrylonitrile copolymer ,
Acrylic ester/vinylidene chloride copolymer, acrylic ester/styrene copolymer, methacrylic ester/acrylonitrile copolymer, methacrylic ester/vinylidene chloride copolymer, methacrylic ester/styrene copolymer, urethane elastomer, Nylon/silicone resin, nitrocellulose/polyamide resin, polyvinyl fluoride, vinylidene chloride/acrylonitrile copolymer, butadiene/acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose) triacetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymers, polyester resins, chlorovinyl ether-acrylic acid ester copolymers, amino resins, various synthetic rubber-based thermoplastic resins, and mixtures thereof. used.

The thermosetting resin or reactive resin has a molecular weight of 200,000 or less in the state of a coating solution, and when heated after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition. Become. Moreover, among these resins, those that do not soften or melt before the resin is thermally decomposed are preferable. Specifically, for example, phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, silicone resin, acrylic reaction resin, epoxy/polyamide resin, nitrocellulose/melamine resin, high molecular weight polyester resin, and isocyanate. mixtures of prepolymers, mixtures of methacrylate copolymers and diisocyanate prepolymers;
Mixture of polyester polyol and polyisocyanate, urea/formaldehyde resin, low molecular weight glycol/
Mention may be made of mixtures of high molecular weight diols/triphenylmethane triisocyanates, polyamine resins and mixtures thereof.

These binders may be used alone or in combination. The mixing ratio of the ferromagnetic fine powder and the binder in the magnetic layer is based on 100 parts by weight of the ferromagnetic fine powder.
The binder ranges from 5 to 300 parts by weight.

As the polishing agent, commonly used materials such as fused alumina, silicon carbide, and chromium oxide (Cr2
O3), corundum, artificial corundum, diamond, artificial diamond, garnet, emery (main components: corundum and magnetite), and the like. These abrasives have a Mohs hardness of 5 or more and an average particle size of 0.05 to 5.
A size of μm is effective, preferably 0.4~
It is 1.5 μm. These abrasives are added in an amount of 7 to 15 parts by weight based on 100 parts by weight of the binder. If this amount is less than 7 parts by weight, sufficient durability cannot be obtained, and if it is more than 15 parts by weight, the degree of filling of the magnetic powder decreases and sufficient output cannot be obtained.

[0037] As the antistatic agent, carbon black,
Conductive fine powder such as carbon black graft polymer; Natural surfactant such as saponin; Nonionic surfactant such as alkylene oxide type, glycerin type, glycidol type; Higher alkylamines, quaternary ammonium salts, pyridine and other complexes Cationic surfactants such as rings, phosphoniums or sulfoniums; anionic surfactants containing acidic groups such as carboxylic acids, sulfonic acids, phosphoric acids, sulfuric acid ester groups, and phosphoric ester groups; amino acids, aminosulfonic acids, and amino alcohols; Examples include amphoteric activators such as sulfuric acid or phosphoric esters.

The above conductive fine powder is used in an amount of 0.2 to 20 parts by weight per 100 parts by weight of the binder, and the surfactant is added in an amount of 0.1 to 20 parts by weight.
It is added in an amount of 10 parts by weight.

[0039] These surfactants are used alone or in combination, but are sometimes used for other purposes, such as dispersion, improving magnetic properties, improving lubricity, and as coating aids. .

As a dispersant (pigment wetting agent), a compound having 12 carbon atoms such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, stearolic acid, etc. ~2
2 fatty acids (R1 COOH, R1 has 11 to 2 carbon atoms)
1 alkyl or alkenyl group); metal soaps made of alkali metals (Li, Na, K, etc.) or alkaline earth metals (Mg, Ca, Ba, etc.) of the above fatty acids; fluorine-containing compounds of the above fatty acid esters Amides of the above fatty acids; Polyalkylene oxide alkyl phosphates; Lecithin; Trialkyl polyolefin oxy quaternary ammonium salts (alkyl has 1 to 5 carbon atoms, olefins include ethylene, propylene, etc.); Other coupling agents (for example, silane); coupling agents, titanium coupling agents, etc.) are used. In addition, higher alcohols having 12 or more carbon atoms and sulfuric esters may also be used. These dispersants are added in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the binder.

As lubricants, dialkylpolysiloxanes (alkyl has 1 to 5 carbon atoms), dialkoxypolysiloxanes (alkoxy has 1 to 4 carbon atoms), monoalkylmonoalkoxypolysiloxanes (alkyl has 1 to 5 carbon atoms),
, alkoxy has 1 to 4 carbon atoms), silicone oil such as phenylpolysiloxane, fluoroalkylpolysiloxane (alkyl has 1 to 5 carbon atoms); conductive fine powder such as graphite; inorganic materials such as molybdenum disulfide, tungsten disulfide, etc. Fine powder; Plastic fine powder such as polyethylene, polypropylene, polyethylene/vinyl chloride copolymer, polytetrafluoroethylene; α-olefin polymer; Unsaturated aliphatic hydrocarbon that is liquid at room temperature (n-olefin double bond is the terminal A compound with approximately 2 carbon atoms bonded to the carbon of
0); Monobasic fatty acids with 12 to 20 carbon atoms and 3 to 20 carbon atoms
Examples include fatty acid esters consisting of 12 monohydric alcohols and fluorocarbons. These lubricants are
It is added in an amount of 0.2 to 20 parts by weight per 100 parts by weight of the binder.

[0042] As the curing agent, a low molecular weight isocyanate compound is preferably used. Examples of the low molecular weight isocyanate compound include tolylene diisocyanate, 4,4'
- Isocyanates such as diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, naphthylene-1,5-diisocyanate, o-toluidine diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, and products of the isocyanates and polyalcohols, Further, polyisocyanates produced by condensation of isocyanates can be exemplified. Commercially available trade names of these low molecular weight isocyanate compounds include Coronate L, Coronate HL, and Coronate 2.
030, Coronate 2031, Millionate MR, Millionate MTL (manufactured by Nippon Polyurethane Co., Ltd.), Takenate D-102, Takenate D-110N, Takenate D-200, Takenate D-202 (manufactured by Takeda Pharmaceutical Co., Ltd.), Desmodur L , Desmodule 1L, Desmodule N, Desmodule HL (manufactured by Sumitomo Bayer, Ltd.), and the like. These can be used alone or in combination of two or more by taking advantage of the difference in curing reactivity.

The magnetic paint in the present invention can be produced by a conventionally known method.

[0044] As the solvent used for preparing the magnetic paint, organic solvents are preferred. Examples of the organic solvent include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, and tetrahydrofuran; methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isopropyl acetate,
Ester solvents such as ethyl lactate, glycol acetate, and monoethyl ether; glycol ether solvents such as ether, glycol dimethyl ether, and dioxane; tar solvents (aromatic hydrocarbons, etc.) such as benzene, toluene, xylene, cresol, chlorobenzene, and styrene; );
Chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and dichlorobenzene, N,N-dimethylformaldehyde, hexane, and the like can be used.

In kneading and dispersing the ferromagnetic powder and each of the above-mentioned components, the ferromagnetic powder and each component are fed into a dispersion machine either simultaneously or individually one after another. For example, there is a method in which magnetic powder is added to a solvent containing a dispersant and the like, and the dispersion is continued for a predetermined period of time to form a magnetic paint. At that time, it is preferable that the magnetic powder is brought into contact with the addition compound (A) in advance,
It is preferable to mix it with other components in this coexistence state. This makes the action of the addition compound (A) more effective.

Various types of dispersing machines can be used for kneading and dispersing the magnetic paint. For example, two-roll mill, three-roll mill, ball mill, pebble mill, tron mill, sand glider, Szegvari attritor, high-speed impeller dispersion machine, high-speed stone mill, high-speed impact mill, disperser, kneader, high-speed mixer, homogenizer, ultrasonic A disperser or the like can be used.

[0047] Also, as a technique related to kneading and dispersion, ``Paint Flow and Pigment Dispersion'' by T.C. Patton (1999)
The technique described in 1975) can be used.

[0048] Conventionally known methods can be used to apply the thus obtained magnetic paint onto a non-magnetic support. For example, two or more magnetic layers may be provided simultaneously by a multilayer simultaneous coating method.

The magnetic layer coated on the non-magnetic support by this method is, if necessary, subjected to a treatment to make the magnetic material in the layer non-oriented as described above, and then dried. If necessary, the surface is smoothed and then punched into a desired shape to form a magnetic disk.

The thickness of the magnetic layer is approximately 0.2 to 12 in terms of dry thickness.
μm, preferably in the range of 0.3 to 4 μm. In the case of multiple layers, the total amount shall be within the above range. Further, this dry thickness may be determined depending on the use, shape, specifications, etc. of the magnetic disk.

This magnetic layer has extremely few surface defects caused by poor dispersion or reagglomeration of the ferromagnetic powder, and has excellent surface smoothness, for example, a center line average roughness (Ra) of 0.020 μm.
This is a magnetic layer that is extremely smooth and has significantly improved recording characteristics at short wavelengths.

[0052]

[Examples] The present invention will be further explained below with reference to Examples. In addition, the characteristics in the example were determined by the following method.

1. Paint dispersion: A magnetic paint is applied to the surface of a polyethylene terephthalate film having a thickness of 75 μm to a thickness of 3.0±1 μm after drying, and is dried and smoothed. The obtained coating film is observed with a differential phase contrast microscope (magnification: 100 times), and the number of irregularities with a diameter of 20 μm or more within the field of view is counted in any one field of view, and this number is taken as the degree of paint dispersion.

2. Short wavelength recording characteristics gap length 0.3μm
Using a 3.5-inch floppy disk drive with a ring-type Mn-Zn ferrite head, the output at recording wavelengths of 0.7 and 1.5 μm is measured at the optimum recording current. This output is shown assuming that the output of a standard disk is 0 dB.

3. High pass modulation adjacent 1
Measure the average signal strength in 00 bit units and divide these into A,
When B, it is shown as the average value of worst to 10 in [(A-B)/(A+B)]×100.

[0056]

[Examples 1 to 10] Hexagonal barium ferrite (specific surface area 50
m2/g, 80 parts by weight
Coercive force 700 Oe) Addition compounds shown in Table 1 (
A)
4 parts by weight Polyurethane (Dainippon Ink Chemical: Pandex T-5250) 6 parts by weight PVC
Vinyl acetate resin (Nissin Chemical: TA5C)
6 parts by weight α-alumina (Sumitomo Chemical: AKP20)
3 parts by weight carbon black (Mitsubishi Kasei: #3950)
5 parts by weight Oleic acid oleyl ester
5 parts by weight cyclohexanone
After mixing and dispersing the composition consisting of 400 parts by weight with a sand grinder, Coronate L (Japan Polyurethane: low molecular weight isocyanate)

10 parts by weight were added and further mixed in a high speed disperser to prepare a magnetic paint.

The obtained magnetic paint was aged at 15° C. for 24 hours, then applied on one side of polyethylene terephthalate with a thickness of 75 μm to a dry thickness of 2.5 μm, and dried after non-orientation treatment. Then, the magnetic layer was calendered. Furthermore, the same treatment was carried out on the back side. After heat treatment at 60° C. for 100 hours, a disk-shaped magnetic disk was produced. Table 1 shows the characteristics of this magnetic disk.

By using the addition compound (A),
As shown in Table 1, the dispersibility of the paint, especially the dispersion stability, was significantly improved. Furthermore, when it comes to industrial products, it is undesirable for there to be variations in quality between the products at the beginning and end of production, but since the paint is stabilized by the use of the additive compound (A), variations in quality are also minimized (with short wavelengths). recording characteristics,
(evaluated with high-pass modulation).

[0059]

[Comparative Example 1] Same as Example 1 except that the addition compound (A) was not used and the amount of polyurethane was changed from 6 parts by weight to 8 parts by weight, and the amount of vinyl chloride/vinyl acetate resin was changed from 6 parts by weight to 8 parts by weight. I did the same.

The characteristics of the obtained magnetic disk are shown in Table 1 as a standard disk.

[0061]

[Table 1]

[0062]

[Examples 11 to 20] Hexagonal barium ferrite (same as Example 1)
80 parts by weight Table 2
Addition compound (A) shown in
4 parts by weight
Sulfobetaine-containing resin (B) shown in Table 2
4 parts by weight Polyurethane (Dainippon Ink Chemical: Pandex T-525
0) 4 parts by weight PVC/PVC resin (Nissin Chemical: TA
5C)
4 parts by weight α-alumina (Sumitomo Chemical: AKP20
) 3 parts by weight Carbon black (Mitsubishi Kasei: #3950
) 5 parts by weight
Oleic acid oleyl ester
5 parts by weight cyclohexanone

After mixing and dispersing the composition consisting of 400 parts by weight with a sand grinder, Coronate L (Japan Polyurethane: low molecular weight polyurethane)

1
0 parts by weight and further mixed in a high-speed disperser,
A magnetic paint was prepared.

A magnetic disk was prepared in the same manner as in Example 1, except that the obtained magnetic paint was aged at 15° C. for 24 hours before use.

Table 2 shows the characteristics of this magnetic disk.

[0065]

[Table 2]

[0066]

[Examples 21 to 30] Ferromagnetic powder shown in Table 3

70 parts by weight Addition compound (A) shown in Table 3

6 parts by weight Polyurethane (Dainippon Ink Chemical: Pandex T-5250) 8 parts by weight PVC/vinyl acetate resin (Nissin Chemical: TA5C)
8 parts by weight α-alumina (Sumitomo Chemical: AKP20)
4 parts by weight Carbon black (Mitsubishi Kasei: #3950)
6 parts by weight oleyl oleate
6 parts by weight cyclohexanone
After mixing and dispersing 400 parts by weight of the composition using a sand grinder, 10 parts by weight of Coronate L (Japan Polyurethane: Low Molecular Weight Isocyanate) was added and further mixed in a high speed disperser to prepare a magnetic paint.

The obtained magnetic paint was aged at 15° C. for 24 hours and then dried on a polyethylene terephthalate film with a thickness of 75 μm. 2.7μ for ferromagnetic powder
The magnetic layer was coated so as to have an orientation of m, dried after non-orientation treatment, and then calendered to the magnetic layer. Thereafter, a magnetic disk was produced in the same manner as in Example 1.

Table 3 shows the characteristics of this magnetic disk.

[0069]

[Comparative Examples 2 and 3] Example 2 except that no additional compound was used and the amount of polyurethane was changed from 8 parts by weight to 11 parts by weight, and the amount of vinyl chloride/vinyl acetate resin was changed from 8 parts by weight to 11 parts by weight.
It was carried out in the same manner as in 1 and 26.

The characteristics of the obtained magnetic disk are shown in Table 3 as a standard disk.

[0071]

[Table 3]

[0072]

[Reference Example 1] 7.2 parts by weight of Desmodur N (75% in a 1:1 mixed solvent of ethyl cellosolve acetate and xylene) was dissolved in 20 parts by weight of xylene.The average molecular weight was 1800.
16.9 parts by weight of caprolactone polyester (obtained in Production A below) and 10 parts of ethyl cellosolve acetate
parts by weight and homogenized under a protective atmosphere, 0.004 parts by weight of dibutyltin dilaurate were added and the reaction mixture was stirred at 60° C. until complete reaction of the OH groups.

For the crosslinking reaction, the reaction mixture was diluted with 10 parts by weight of xylene and 0.8 parts by weight of 1,12-diaminododecane dissolved in 10 parts by weight of N-methyl-pyrrolidone were immediately added.

When 66% of the NCO groups initially subjected to the reaction had reacted, the reaction mixture was diluted with 13.2 parts by weight of xylene, and N,
1.9 parts by weight of N-diallylmelamine was added.

The reaction mixture was heated to 70° C. and stirred at this temperature for 1 hour.

The final product was a colorless, clear to slightly hazy material with medium viscosity.

[Production of caprolactone polyester: Production A] 7.2 parts by weight of n-octanol, 92.8 parts by weight of caprolactone, and 0.0 parts by weight of dibutyltin dilaurate.
0.3 parts by weight were homogenized under a protective atmosphere and the
Heated to 60°C. The addition reaction was terminated as soon as a solids content of 99% was obtained. At this temperature this solids content was achieved in 10-12 hours. A product was obtained which was a colorless solid at room temperature, with a melting point of 50-60°C.

[0078]

[Reference Example 2] Desmodur N (75% in a 1:1 mixed solvent of ethyl cellosolve acetate and xylene) under a protective atmosphere
) 10.4 parts by weight was diluted with 10 parts by weight of ethyl cellosolve acetate and dissolved in 20 parts by weight of xylene, with an average molecular weight of 11.
00 caprolactone polyester (obtained in Preparation B below) was added. Dibutyltin dilaurate 0.0
After adding 0.4 parts by weight, the reaction mixture was heated to 60°C.

When 33% of the NCO groups initially subjected to the reaction had reacted, 0.6 parts by weight of trimethylolpropane dissolved in 30 parts by weight of xylene was added.

Immediately after 66% of the NCO groups have reacted, 4 parts by weight of ethyl cellosolve acetate is added.
1.6 parts by weight of -(2-hydroxyethyl)-pyridine were added and the reaction mixture was heated to 70°C and stirred at this temperature for 1 hour. The final product was colorless and of medium viscosity.

[Production of caprolactone polyester: Production B] 11.1 parts by weight of phenylethyl alcohol and 88.9 parts by weight of caprolactone were homogenized at room temperature, and 0.002 parts by weight of dibutyltin dilaurate was added as a catalyst under a nitrogen atmosphere.
Added parts by weight. The reaction mixture was heated to 160° C. within 1 hour and stirred at this temperature. The reaction was terminated as soon as a solids content of 99% was obtained.

[0082] Polyester has a melting point of 50 to 60°C.
% product or as a 50% mixture with xylene, for example. The latter was solid at room temperature and had a melting point of 40-50°C.

[0083]

[Reference Example 3] Desmodur N (75% in a 1:1 mixed solvent of ethyl cellosolve acetate and xylene) under a protective atmosphere
) 10.3 parts by weight, 20 parts by weight of ethyl cellosolve acetate,
and the average molecular weight dissolved in 15 parts by weight of xylene is 75
homogenized with 0 commercially available methoxypolyethylene glycol,
After adding 0.004 parts by weight of dibutyltin dilaurate, the reaction mixture was heated to 50°C.

After 1/3 of the NCO groups had reacted, 5.4 parts by weight of polyethylene glycol having an average molecular weight of 800 dissolved in 15 parts by weight of xylene was added.

When 66% of the NCO groups had reacted, the reaction mixture was diluted with 12.4 parts by weight of xylene and 1.7 parts by weight of 1-(2-aminoethyl)-piperazine dissolved in 10 parts by weight of ethyl cellosolve acetate. Added parts by weight. The reaction mixture was stirred at 70° C. for 2 hours, yielding a yellow, slightly viscous product.

[0086]

[Reference Example 4] 9.1 parts by weight of Desmodur N (75% in a 1:1 mixed solvent of ethyl cellosolve acetate and xylene), 17.7 parts by weight of ethyl cellosolve acetate, 0.003 parts by weight of dibutyltin dilaurate, and 10 parts by weight of xylene 13 parts by weight of caprolactone polyester having an average molecular weight of 1100 (obtained in Preparation B above) dissolved in parts by weight were homogenized under a protective atmosphere and heated to 50°C. After chemical addition of the polyester, ethoxylated oleylamine 3 with an average molecular weight of 630 dissolved in 30 parts by weight of xylene
．． 7 parts by weight were added.

As soon as 66% of the NCO groups have reacted, 4-(2
-Aminoethyl)-pyridine (1.5 parts by weight) was added, the reaction mixture was stirred for 1 hour to complete the reaction, and after cooling, acetic acid
．． 8 parts by weight was added to carry out a neutralization reaction. The product solution had a medium viscosity and was slightly cloudy and brown in color.

[0088]

[Reference Example 5] 7.6 parts by weight of Desmodur N (75% in a 1:1 mixed solvent of ethyl cellosolve acetate and xylene), 18.1 parts by weight of xylene, and adipic acid and dodecane dissolved in 10 parts by weight of xylene. Polyester of diol and octanol with an average molecular weight of 1400 (Production C below)
13.3 parts by weight (obtained in ) were homogenized under a protective atmosphere, 0.003 parts by weight of dibutyltin dilaurate were added and the reaction mixture was heated to 40°C. 66% of NCO groups
When the reaction has finished, trimethylolpropane-caprolactone polyester (
4.5 parts by weight (obtained in Production D below) was added.

After addition of the hydroxyl group, 1 part by weight of N,N-dimethyl-1,3-propanediamine dissolved in 15 parts by weight of N-methylpyrrolidone was added, and the reaction mixture was heated to 60°C and stirred for 1 hour. . The product was highly viscous and colorless.

[Production of polyester: Production C] 38 parts by weight of adipic acid, 52.7 parts by weight of dodecanediol, 9.3 parts by weight of octanol, 0.0 parts by weight of p-toluenesulfonic acid.
1 part by weight and 30 parts by weight of toluene were homogenized and heated. The produced water was azeotropically distilled off within 5-6 hours and the temperature reached 140-150°C. The solvent was then carefully distilled under vacuum. The polyester produced was solid at room temperature and had a melting point of 70-80°C.

[Production of caprolactone polyester: Production D] 6 to 8 hours after adding 0.003 parts by weight of dibutyltin dilaurate using 9.6 parts by weight of trimethylolpropane and 90.4 parts by weight of caprolactone as catalysts.
The reaction was carried out at 170°C until a polyester having an average molecular weight of 1400 was obtained.

[0092]

[Reference Example 6] 12.9 parts by weight of Desmodur L (67% in a 1:1 mixed solvent of ethyl cellosolve acetate and xylene) was added to 20 parts by weight of a 1:1 mixed solvent of ethyl cellosolve acetate and xylene under a protective atmosphere. Diluted. 9 parts by weight of commercially available methoxypolyethylene glycol having an average molecular weight of 750 dissolved in 10 parts by weight of xylene and 0.003 parts by weight of dibutyltin dilaurate were added. 33 of NCO group at 50℃
%, 6 parts by weight of caprolactone polyester having an average molecular weight of 1000 dissolved in 20 parts by weight of xylene obtained in Preparation E below were added. 66% of NCO groups
The reaction stopped immediately after it finished reacting. xylene 2
1-(2-hydroxyethyl) dissolved in 0.7 parts by weight
-1.4 parts by weight of imidazole were added for the addition of the remaining NCO groups and the reaction mixture was stirred at 70° C. for 2 hours.

A colorless, transparent and slightly viscous product was obtained.

[Production of polycaprolactone polyester: Production E] 9 parts by weight of 1,4-butanediol, 91 parts by weight of caprolactone, and 0.0 parts by weight of dibutyltin dilaurate.
002 parts by weight were homogenized under a protective atmosphere and heated to 160° C. within 1 hour. The addition reaction was terminated as soon as the solids content was above 99%. The produced polyester diol had an average molecular weight of 1000.

[0095]

[Reference Example 7] 14.3 parts by weight of a polyester of adipic acid, dodecanediol and octanol with an average molecular weight of 1400 (obtained in the above production C) was heated at 50°C with 15 parts by weight of ethyl cellosolve acetate and 10 parts by weight of xylene. under a protective atmosphere. The reaction mixture was cooled to 20° C. and 11.1 parts by weight of Desmodur L (67% in a 1:1 mixed solvent of ethyl cellosolve acetate and xylene) and 0.003 parts by weight of dibutyltin dilaurate were added with stirring. The reaction mixture was slowly heated to 50° C. and the progress of the reaction was followed by quantification of NCO groups. N.C.O.
After 1/3 of the groups have reacted, add polyethylene glycol 2 with an average molecular weight of 400 dissolved in 20 parts by weight of xylene.
．． 1 part by weight was added, leaving the remaining 1/3 of the NCO groups for the next reaction. The reaction mixture was then diluted with 11.4 parts by weight of xylene and diluted with N dissolved in 15 parts by weight of N-methylpyrrolidone.
, 1.1 parts by weight of N-dimethyl-1,3-diaminopyrropane were added. The reaction mixture was stirred at 50° C. for 1 hour, and further 0.75 parts by weight of acetic acid was added. The product was a slightly viscous yellow solution.

[0096]

[Reference Example 8] 8.8 parts by weight of Desmodur L (67% in a 1:1 mixed solvent of ethyl cellosolve acetate and xylene) in 15 parts by weight of ethyl cellosolve acetate was homogenized under a protective atmosphere, and nonylphenol ethyl oxylate was (ox
15.5 parts by weight of caprolactone polyester (obtained in Preparation F below), obtained starting from ylate) and dissolved in 12.2 parts by weight of xylene, were added together with 0.002 parts by weight of dibutyltin dilaurate. The reaction mixture was heated to 50° C. and stirred until 30% of the NCO groups had reacted. Next, the reaction solution was diluted with 20 parts by weight of xylene, and commercially available polytetrahydrofuran diol having an average molecular weight of 650 dissolved in 10 parts by weight of xylene was added.

As soon as 66% of the NCO groups have reacted, 0.9 parts by weight of 4-(aminomethyl)-pyridine dissolved in 15 parts by weight of xylene is added and the reaction mixture is heated to 70°C.
and stirred at this temperature for 1 hour. A colorless and very low viscosity product was obtained.

[Production of caprolactone polyester: Production F] 23.4 parts by weight of alkali-free dehydrated nonylphenol ethoxylate having an average molecular weight of 445 was mixed with 76.6 parts by weight of caprolactone and 0.004 parts by weight of dibutyltin dilaurate under a protective atmosphere. It was homogenized with The reaction mixture was heated to 150°C and stirred at this temperature for 20 hours. A colorless, waxy product with a solids content of 98% was obtained.

0099

[Reference Example 9] 12.4 parts by weight of ethyl cellosolve acetate, Desmodur L (1 part of ethyl cellosolve acetate and xylene)
11 parts by weight of 67%) and 2 parts by weight of xylene in a mixed solvent
14.2 parts by weight of a polyester with an average molecular weight of 1400 (obtained in Preparation C above) of adipic acid, dodecanediol and octanol dissolved in 0 parts by weight are homogenized under a protective atmosphere and 0.003 parts by weight of dibutyltin dilaurate are dissolved. added. The polyester was chemically added to Desmodur L by heating the reaction mixture to 50°C.

After this reaction step, 2.2 parts by weight of commercially available coconut acid diethanolamide dissolved in 30 parts by weight of a 1:1 mixture of ethyl cellosolve acetate and xylene were added. The average molecular weight of coconut oil diethanolamide is 440
Met. As soon as 2/3 of the NCO groups have reacted, 1.3 parts by weight of 1-(3-aminopropyl)-imidazole dissolved in 10 parts by weight of NMP are immediately added, and the reaction mixture is heated to 70°C and maintained at this temperature. The mixture was stirred for 1 hour. A clear to slightly cloudy product with medium viscosity was obtained.

[0101]

[Reference Example 10] Polyisophorone diisocyanate dissolved in 10 parts by weight of ethyl cellosolve acetate (70% in a 1:1 mixed solvent of ethyl cellosolve acetate and xylene) 7.9
parts by weight, and valerolactone polyester with an average molecular weight of 2000 dissolved in 20 parts by weight of xylene (Production G below)
(15 parts by weight) were homogenized under a protective atmosphere excluding moisture. Dibutyltin dilaurate 0.003
parts by weight were added and the reaction mixture was heated to 50°C. When the OH groups have completely reacted, polypropylene glycol 3 with an average molecular weight of 1000 dissolved in 20 parts by weight of xylene
．． 7 parts by weight were added.

When 66% of the NCO groups have reacted, 7.6 parts by weight of xylene and 15 parts by weight of N-methylpyrrolidone
0.8 parts by weight of 3-mercapto-1,2,4-triazole dissolved in parts by weight were added, and the reaction mixture was stirred at 60°C for 1 hour.

The product solution had a low viscosity and a slightly brown color.

[Production of valerolactone polyester: Production G] 2.1 parts by weight of commercially available heptadecafluorodecanol having an average molecular weight of 445 was mixed with 5.9 parts by weight of 2-ethylhexanol and valero at 60°C under a protective atmosphere. It was homogenized with 92 parts by weight of lactone. 0.004 parts by weight of dibutyltin dilaurate was added to the reaction mixture and 18
Heated to 0°C. The reaction mixture was stirred until the solids content was 98%.

A colorless to slightly yellowish solid product was obtained at room temperature, with a melting point of 60-70°C.

[0106]

[Reference Example 11] Desmodur HL (6 in butyl acetate)
Caprolactone polyester (0%) with an average molecular weight of 1100 was dissolved in 20 parts by weight of ethyl acetate cellosolve from which moisture had been removed, and 20 parts by weight of xylene.
11.6 parts by weight of the product obtained in Preparation B) and 0.003 parts by weight of dibutyltin dilaurate were added, and the reaction mixture was gently heated to 60°C.

The first step was completed as soon as 30% of the NCO groups had reacted.

Xylene 14. for the coupling reaction.
3.4 parts by weight of commercially available polytetrahydrofuran diol having an average molecular weight of 650 dissolved in 4 parts by weight were added.

As the final step following completion of 60% reaction of NCO groups, 1.5 parts by weight of 3-mercapto-1,2,4-triazole dissolved in 15 parts by weight of N-methylpyrrolidone was added, and the reaction mixture was reduced to 70% by weight. ℃ and stirred at this temperature for 1 hour. The product solution was viscous, slightly yellow and almost clear.

[0110]

Reference Example 12 The reaction was carried out at 50°C under a protective atmosphere. Desmodur HL (60% in butyl acetate) 14.4
part by weight of ethyl cellosolve acetate was dissolved in 15 parts by weight of ethyl cellosolve acetate to obtain caprolactone polyester having an average molecular weight of 1100 obtained starting from phenylethyl alcohol (preparation B above).
9.9 parts by weight of the product obtained in Example 1) were added. The polyester was partially dissolved in 13 parts by weight of xylene.

When the addition reaction of the polyester was completed by quantifying the NCO groups, 4.5 parts by weight of polyethylene glycol having an average molecular weight of 1000 was added. In order to react with the remaining NCO groups, 1-(2-aminoethyl)-
2.3 parts by weight of piperazine were added and the reaction mixture was diluted with xylene to a solids content of 30%. A slightly cloudy viscous solution was added as product.

[0112]

[Reference Example 13] Desmodur HL (6 in butyl acetate)
0%) was diluted with 30 parts by weight of a 1:1 mixture of xylene and ethyl cellosolve acetate under protective gas to give 12.7 parts by weight of polyester with an average molecular weight of 2000 (obtained in Preparation G above). Added a section. After adding 0.003 parts by weight of dibutyltin dilaurate, the addition reaction was carried out at room temperature.

When 25% of the NCO groups had reacted, 4.7 parts by weight of polyethylene glycol having an average molecular weight of 1500 was added as a second step.

When 50% of the NCO groups have reacted, the reaction mixture is diluted with xylene to a final solid product content of 25% and 1.5 parts by weight of 4-(2-aminoethyl)-pyridine is added. added. heating the reaction mixture to 60°C;
Stirred at this temperature for 1 hour. A slightly yellow and viscous product was obtained.

[0115]

Reference Example 14 The reaction was carried out at 50°C under a protective gas. 6.3 parts by weight of Desmodur HL (60% in butyl acetate) was mixed with 15 parts by weight of ethyl cellosolve acetate and 36 parts by weight of xylene.
Diluted with a mixed solution of 0.7 parts by weight of polyethylene glycol with an average molecular weight of 400 and an average molecular weight of 5000.
19.6 parts by weight of caprolactone polyester (obtained in Production H below) were added. 0.002 parts by weight of dibutyltin dilaurate was added to accelerate the reaction.

When all OH groups have reacted, 4-
0.9 parts by weight of (2-hydroxyethyl)-pyridine was added and the solids content of the reaction mixture was adjusted to 25% with xylene. The reaction mixture was stirred at 60° C. for 1 hour until the reaction was complete. A colorless, low viscosity product was obtained.

[Production of caprolactone polyester: Production H] 2.9 parts by weight of isononanol, 9 parts by weight of caprolactone
7.1 parts by weight and 0.00 parts of dibutyltin dilaurate
2 parts by weight were homogenized under a protective atmosphere to give 17% within 1 hour.
Heated to 0°C. The reaction was terminated as soon as a solids content of 99.5% was obtained after 8-10 hours. A product was obtained which was a colorless solid at room temperature, with a melting point of 60-70<0>C.

[0118]

[Reference Example 15] Desmodur HL (6 in butyl acetate)
0%) 10.7 parts by weight of xylene 15 under a protective atmosphere.
．． Obtained starting from 7 parts by weight and heptadecafluorodecanol/2-ethylhexanol, average molecular weight 2000
was homogenized with a solution of 16.2 parts by weight of valerolactone polyester (obtained in Preparation G above). 0.001 part by weight of dibutyltin dilaurate was added, and the polyester addition reaction was carried out at 50°C.

After the reaction was completed, the reaction mixture was diluted with 20 parts by weight of ethyl cellosolve acetate, and 0.3 parts by weight of 1,4-butanediamine dissolved in 20 parts by weight of xylene was added.

As soon as 55% of the NCO groups had reacted, the slightly exothermic reaction was stopped by adding 2.1 parts by weight of 2-amino-6-methoxybenzothiazole dissolved in 15 parts by weight of NMP. The reaction mixture was heated to 70°C and stirred for 1 hour.

A slightly viscous, yellow, and transparent solution was obtained as the product.

[0122]

[Reference Example 16] Desmodur IL (5 in butyl acetate)
1%) and 11 parts by weight of caprolactone polyester with an average molecular weight of 1800 (obtained in Preparation A above) dissolved in 20 parts by weight of xylene were dissolved in 20 parts by weight of ethyl cellosolve acetate/xylene (1:1). Added under a protective atmosphere and 0.0% dibutyltin dilaurate as catalyst.
After adding 0.002 parts by weight, an addition reaction was carried out at room temperature.

When 20% of the NCO groups had reacted, 3.8 parts by weight of polycaprolactone polyester (obtained in Preparation E above) dissolved in 17.1 parts by weight of xylene were added.

After 55% of the NCO groups have reacted, 2.0 parts of 4-(2-aminoethyl)-pyridine dissolved in 10 parts by weight of xylene and 10 parts by weight of isobutyl ketone is added.
Added parts by weight. The reaction mixture was heated to 50°C and stirred for 1 hour. A colorless, slightly yellow and low viscosity product was obtained.

[0125]

[Reference Example 17] Desmodur IL (5 in butyl acetate)
1%) 9 parts by weight of polyester with an average molecular weight of 5000 (
17 parts by weight of the product obtained in Production H) and 25 parts by weight of xylene
The mixed solution with parts by weight was homogenized under a protective atmosphere excluding moisture, and 0.003 parts by weight of dibutyltin dilaurate was added. The reaction was carried out at 60°C. After the polyester addition reaction, 30 parts by weight of xylene with an average molecular weight of 10
2.5 parts by weight of polypropylene glycol No. 00 was added. Dibutyltin dilaurate 0.0 to accelerate the reaction
02 parts by weight were added. When the hydroxyl groups have finished reacting, the reaction mixture is diluted with 5.6 parts by weight of xylene, and the remaining NCO groups are dissolved in 10 parts by weight of N-methylpyrrolidone and 0.9 parts by weight of 3-mercapto-1,2,4-triazole. Added a section. A medium viscous, yellow product was obtained.

[0126]

[Reference Example 18] Desmodur IL (5 in butyl acetate)
1%) 15.5 parts by weight of xylene 15 under a protective atmosphere.
Polyester with an average molecular weight of 1800 dissolved in parts by weight (
The mixture was homogenized with 13.3 parts by weight (obtained in Preparation A), 0.003 parts by weight of dibutyltin dilaurate was added, and the reaction mixture was heated to 50°C. After the addition reaction of the polyester (25% of the NCO groups reacted, which can be seen quantitatively), the reaction mixture was diluted with 20 parts by weight of xylene and 1.
0.7 parts by weight of 12-diaminododecane was added.

After an exothermic reaction, 14 parts by weight of xylene and N-
1.5 parts by weight of N,N-dimethyl-1,3-propanediamine dissolved in 20 parts by weight of methylpyrrolidone was added. Stirring at 70° C. for 1 hour gave a medium viscous and slightly cloudy product.

[0128]

[Reference Example 19] Desmodur IL (5 in butyl acetate)
1%) under a protective atmosphere, 30 parts by weight of xylene/butyl acetate (4:1) and an average molecular weight of 180
0 polyester (obtained in production A above) 26.
It was homogenized to 6 parts by weight. Dibutyltin dilaurate 0.
When 003 parts by weight were added and the reaction mixture was heated to 50°C, 50% of the NCO groups had reacted.

0.3 parts by weight of 1,4-butanediol dissolved in 30 parts by weight of xylene was added. 75% of NCO groups
When the reaction has finished, 0.6 parts of 3-amino-1,2,4-triazole dissolved in 10 parts by weight of N-methylpyrrolidone
parts by weight were added and the solids content was adjusted to 30% with xylene. The medium viscous, yellow product was stirred at 60° C. for 1 hour.

[0130]

[Reference Example 20] A polyester polyol (hydroxyl value 115) consisting of adipic acid and 1,4-butanediol (hydroxyl value 115
．． 3) 262.8 parts by weight, polyester polyol with a hydroxyl number of 187 (obtained in the following Production J) 13
8 parts by weight, propylene oxide adduct of bisphenol A (hydroxyl number 311.7) 46.8 parts by weight, diphenylmethane diisocyanate 150 parts by weight, methyl ethyl ketone 697.2 parts by weight, toluene 697.2 parts by weight, dibutyltin dilaurate 0.2 parts by weight I prepared a section. Stir at 80 °C until the viscosity is constant, sulfometine is 35 equivalents/106 g, and the molecular weight is 33.0
00 urethane resin was obtained.

[Production of polyester polyol: Production J
] In a reaction vessel equipped with a stirrer, a thermometer, and a partial reflux condenser, 182.6 parts by weight of adipic acid and 207 parts by weight of isophthalic acid were added.
．． 6 parts by weight, 95.0 parts by weight of ethylene glycol, 1,
233.9 parts by weight of 6-hexane glycol and 24.13 parts by weight of a compound represented by the following formula A (Chemical formula 11) were charged. The esterification reaction was carried out at 160 to 220°C to obtain a polyester polyol having a hydroxyl value of 187.

[0132]

[Chemical formula 11]

[0133]

[Reference Example 21] Polycarbonate diol (Daicel (
Co., Ltd., Plaxel CD210, hydroxyl value 107
．． 6) 521.4 parts by weight, 300 parts by weight of polyester polyol (obtained in the above Production J), 8.9 parts by weight of trimethylolpropane, 48 parts by weight of 1,4-butanediol
．． Reference Example 2 using 2 parts by weight, 163.5 parts by weight of TDI-80, 128.1 parts by weight of isophorone diisocyanate, 585 parts by weight of methyl ethyl ketone, 585 parts by weight of toluene, and 0.23 parts by weight of dibutyltin dilaurate.
A urethane resin was obtained in the same manner as in Example 0. This urethane resin had a sulfobetaine content of 40 equivalents/106 g and a molecular weight of 1,500.

[0134]

[Reference Example 22] Adipic acid 329.8 parts by weight, isophthalic acid 374.9 parts by weight, ethylene glycol 179.0 parts by weight
A polyester polyol having a hydroxyl value of 114 was obtained in the same manner as in Production J using 292.6 parts by weight of neopentyl glycol and 4.82 parts by weight of the compound represented by formula A (Chemical formula 11).

500 parts by weight of this polyester polyol, 9.7 parts by weight of 1,4-butanediol, TDI-80
104.5 parts by weight, methyl ethyl ketone 716.8
A urethane resin was obtained in the same manner as in Reference Example 20 using 716.8 parts by weight of toluene and 0.2 parts by weight of dibutyltin dilaurate. This urethane resin has 16 equivalents/106 g of sulfobetaine and a molecular weight of 68,000.
Met.

[0136]

[Reference Example 23] Adipic acid 329.8 parts by weight, isophthalic acid 374.9 parts by weight, ethylene glycol 171.9 parts by weight
A polyester polyol having a hydroxyl value of 110 was obtained in the same manner as in Production J using 286.9 parts by weight of neopentyl glycol and 24.13 parts by weight of the compound represented by formula A (Chemical formula 11).

510 parts by weight of this polyester polyol, 4.95 parts by weight of 1,4-butanediol, 19.8 parts by weight of propylene oxide adduct of bisphenol A (hydroxyl number 311.7), 74 parts by weight of methyl ethyl ketone.
A urethane resin was obtained in the same manner as in Reference Example 20 using 5.8 parts by weight, 745.8 parts by weight of toluene, and 0.21 parts by weight of dibutyltin dilaurate. This urethane resin contains 78 equivalents/106 g of sulfobetaine and has a molecular weight of 58
,000.

[0138]

[Reference Example 24] After replacing nitrogen in a stainless steel autoclave, 1620 parts by weight of vinyl chloride, 291 parts by weight of vinyl acetate, 81 parts by weight of allyl glycidyl ether, and the following formula B (
11 parts by weight of sulfobetaine-containing acrylamide represented by formula 12), 4000 parts by weight of methanol, and 20 parts by weight of di-2-ethylhexyl peroxydicarbonate were charged, and the temperature was raised to 40° C. with stirring to start the reaction. After reacting for 12 hours, the residual pressure was released and the slurry was cooled, filtered, washed with deionized water, and dried to obtain 1311 parts by weight of copolymer powder. As a result of analysis, this copolymer consists of 83.3% by weight of vinyl chloride, 12.8% by weight of vinyl acetate, 3.6% by weight of allyl glycidyl ether, and 0.3% by weight of sulfobetaine-containing acrylamide, and has an average degree of polymerization. It was 330.

[0139]

[Chemical formula 12]

[0140]

Reference Example 25 1000 parts by weight of the above copolymer, 3000 parts by weight of methanol and 35 parts by weight of sodium hydroxide were added to a reactor equipped with a reflux condenser, and a saponification reaction was carried out at 50°C for 4 hours. After the reaction was completed, unreacted sodium hydroxide was neutralized, washed with methanol and deionized water, filtered and dried to obtain 914 parts by weight of a vinyl chloride copolymer. As a result of analysis, this copolymer contained 88.7% by weight of vinyl chloride,
Consisting of 1.3% by weight of vinyl acetate, 6.0% by weight of vinyl alcohol, and 3.8% by weight of allyl glycidyl ether,
The average degree of polymerization was 300.

[0141]

[Reference Example 26] 1511 parts by weight of vinyl chloride, 395 parts by weight of vinyl acetate, 15 parts by weight of sulfobetaine-containing acrylamide represented by the above formula B (Chemical formula 12), 10 parts by weight of benzoyl peroxide, and 8 parts by weight of potassium hydroxide in the saponification reaction A reaction was carried out in the same manner as in Reference Example 35 using parts by weight, with an average degree of polymerization of 380, vinyl chloride 87.3% by weight, vinyl acetate 5.8% by weight, vinyl alcohol 6.5% by weight, and sulfobetaine-containing acrylamide 0. A vinyl chloride copolymer containing 4% by weight was obtained.

[0142]

Effects of the Invention According to the present invention, the dispersibility and dispersion stability of ferromagnetic powder in a magnetic coating material are improved, the surface smoothness of the magnetic coating film is improved, and excellent magnetic recording properties, especially high-density magnetic recording. A flexible magnetic disk with specific properties can be provided.

Claims (3)

[Claims] 1. A flexible magnetic disk comprising a coating film of a magnetic paint containing ferromagnetic powder on a non-magnetic support, wherein the magnetic paint contains (A) an average of 2.5 to A flexible magnetic disk characterized by containing an addition compound derived from a polyisocyanate having six isocyanate groups and a compound reactive with the isocyanate groups. 2. The flexible magnetic disk according to claim 1, wherein the magnetic paint contains (B) a resin containing sulfobetaine. 3. The flexible magnetic disk according to claim 1, wherein the ferromagnetic powder is hexagonal barium ferrite powder.