JPH06340845A - Polyurethane resin binder for magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide a polyurethane resin binder which has an excellent ability to disperse fine magnetic particles and can give a magnetic recording medium of excellent storage stability. CONSTITUTION:The binder comprises a polyurethane resin made from a long- chain polyol, a chain extender and an organic diisocyanate, wherein part or all of the chain extender contains tertiary nitrogen atoms, and part or all of the tertiary nitrogen atoms of this resin are quaternized with a sulfonate compound of general formula: R-SO3-R' (wherein R is 1-12C alkyl or aryl; and R' is 1-8C alkyl).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder for use in a coating type magnetic recording medium in which a magnetic recording layer having fine powdery magnetic particles dispersed in a binder is formed on a non-magnetic support. The present invention relates to a polyurethane resin binder having excellent dispersibility of fine powder magnetic particles and providing excellent storage stability of a magnetic recording medium.

[0002]

2. Description of the Related Art Generally, as the recording density of a magnetic recording medium is increased, the magnetic powder used tends to be finer, and a binder having a high dispersibility is demanded, but a slight alteration of the binder causes a large recording. To affect
A binder having excellent storage stability is required. Generally, polyurethane is a useful binder because it has good abrasion resistance, but it cannot be said that the dispersibility is particularly good. Therefore, a polyurethane resin containing a highly hydrophilic quaternary ammonium salt has been conventionally proposed. By introducing a quaternary ammonium salt group into the polyurethane resin, the affinity with the magnetic powder is increased and the dispersibility is improved, but on the other hand, the water absorption is increased and the polyurethane resin is liable to deteriorate due to moisture etc. Have. For example, JP-A-54-15300
No. 9 discloses improvement in dispersibility by quaternizing a tertiary amino group-containing binder with a dialkyl sulfuric acid, an alkyl halide or an aryl halide. In addition, JP-A-3-153785 and JP-A-3153785.
Japanese Patent Laid-Open No. 188178 discloses a polyurethane resin binder in which a quaternary ammonium salt-containing active hydrogen compound is used as a polyurethane-forming raw material, whereby the solution stability of the polyurethane resin is good and the dispersibility is improved. . Although the dispersibility of the polyurethane resin obtained by these is improved, it has the drawback that storage stability is poor.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made for the purpose of providing a polyurethane resin as a binder for a magnetic recording medium, which overcomes the conventional drawbacks and has excellent dispersibility and storage stability. Is.

[0004]

As a result of earnest research, the inventors of the present invention have found that a tertiary amino group-containing compound is used as a raw material for a polyurethane resin in order to develop the above-mentioned polyurethane resin binder for a high performance magnetic recording medium. Thus, a tertiary amino group is randomly introduced into the polyurethane resin, and by further quaternizing with a specific sulfonic acid ester,
The purpose is that the quaternary ammonium salt is not localized, uniform dispersibility is obtained, the hydrolysis resistance of the polyurethane resin is not deteriorated, and the dispersibility is higher than the conventional type. They have found that they can be sufficiently achieved, and have completed the present invention based on this finding.

That is, the present invention relates to a polyurethane resin formed from a long chain polyol, a chain extender and an organic diisocyanate, which contains a part of the chain extender or a tertiary nitrogen atom, and further contains a tertiary nitrogen atom in the polyurethane resin. A polyurethane resin binder for a magnetic recording medium, characterized in that part or all of the primary nitrogen atoms are quaternized with a sulfonate compound represented by the following general formula (I). R—SO ₃ —R ′ (I) (In the formula, R represents an alkyl group or aryl group having 1 to 12 carbon atoms, and R ′ represents an alkyl group having 1 to 8 carbon atoms.)

Each component constituting the polyurethane resin of the present invention will be described below. Examples of the long-chain polyol used in the present invention include polyester polyols, polyester amide polyols, polyether polyols, polyether ester polyols, polycarbonate polyols and polyalkylene diols. These long-chain polyols are used alone or in combination. May be.

Specific examples of the polyester polyol, polyester amide polyol, polyether polyol and polyether ester polyol include known succinic acid, adipic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, orthophthalic acid, Dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid or their acid esters, acid anhydrides, etc.
Acid ester / anhydride and ethylene glycol, 1,3-
Propylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-
Pentanediol, neopentyl glycol, 1,8-
Octanediol, 1,9-nonanediol, diethylene glycol, 1,4-cyclohexanediol, 1,
4-cyclohexanedimethanol, N-methyldimethanolamine, N-methyldiethanolamine, N-methyldipropanolamine, N-methyldihexanolamine, N-methyldioctanolamine or N-ethyl-substituted compounds thereof, N-propyl Substituted compound, N
-Butyl-substituted compound, N-phenyl-substituted compound, 3-dimethylamino-1,2-propanediol, 4-dimethylamino-1,2-butanediol, 5-dimethylamino-1,3-pentanediol, or these Diethyl amination, 4- (3-hydroxy-2-hydroxymethyl) propyl-N, N-dimethylaniline, 4-
(4-hydroxy-3-hydroxymethyl) butyl-
Ethylene oxide or propylene oxide addition of N, N-dimethylaniline, or diethylaniline compounds, diphenyl compounds, N, N- (dimethyl) -N ', N'-diisopropanol-1,3-propanediamine or bisphenol A thereof. Such as glycol, hexamethylenediamine, xylylenediamine, isophoronediamine, monoethanolamine and other diamines, aminoalcohols, etc., or a polyester polyol, polyesteramide polyol, or ε-caprolactone obtained by dehydration condensation reaction with a mixture thereof. , Lactone-based polyester polymers obtained by ring-opening polymerization of cyclic ester (lactone) monomers such as alkyl-substituted ε-caprolactone, δ-valerolactone, and alkyl-substituted δ-valerolactone. There are polyester polyols, such as all, polyether polyols, such as polyethylene glycol, polypropylene ether polyol, polytetramethylene ether polyol and the like. As a polyether ester polyol,
Examples thereof include polyester polyols produced from the above polyether polyols and the above dicarboxylic acids or anhydrides.

As the polycarbonate polyol, generally, a deethanolic condensation reaction of a polyhydric alcohol and diethyl carbonate, a dephenol condensation reaction of a polyhydric alcohol and diphenyl carbonate, or a deethylene glycol condensation reaction of a polyhydric alcohol and ethylene carbonate is performed. The obtained polyhydric alcohol includes 1,6-hexanediol, diethylene glycol, propylene glycol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,5-pentanediol, neopentyl glycol, Aliphatic diols such as 1,8-octanediol, 1,9-nonanediol and 1,10-decanediol, or alicyclic diamines such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol. Polycarbonate polyols consisting Lumpur is used. Specific examples of polyalkylene diols include hydroxyl-terminated polybutadiene and hydrogenated products thereof. The molecular weight of these long-chain polyols is preferably 500 to 5,000.

The chain extender containing no tertiary nitrogen atom used in the present invention includes ethylene glycol, 1,3
-Propylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-
Pentanediol, neopentyl glycol, 1,8-
Octanediol, 1,9-nonanediol, diethylene glycol, 1,4-cyclohexanediol, 1,
4-cyclohexanedimethanol, glycol such as ethylene oxide or propylene oxide adduct of bisphenol A, hexamethylenediamine, xylenediamine, isophoronediamine, monoethanolamine, diamine such as N, N'-dimethylethylenediamine or amino alcohol. In addition, JP-A-6
Water and urea which react with the isocyanate group shown in 1-107531 to form a urea bond can also be used as the chain extender. These above compounds can be used alone or in the form of a mixture thereof.

Specific examples of the tertiary amino group-containing active hydrogen compound used as a part or all of the chain extender in the present invention include N-methyldimethanolamine, N-methyldiethanolamine and N-methyldipropanol. Amine, N-methyldihexanolamine, N-methyldioctanolamine or their N-ethyl-substituted compounds, N-propyl-substituted compounds, N-butyl-substituted compounds,
N-phenyl substituted compound, 3-dimethylamino-1,2
-Propanediol, 4-dimethylamino-1,2-butanediol, 5-dimethylamino-1,3-pentanediol, or their diethyl amination compounds, 4-
(3-Hydroxy-2-hydroxymethyl) propyl-
N, N-dimethylaniline, 4- (4-sidoxy-3
-Hydroxymethyl) butyl-N, N-dimethylaniline, or diethylaniline compounds thereof, diphenyl compounds, N, N- (dimethyl) -N ', N'-diisopropanol-1,3-propanediamine and the like. .

The concentration of the introduced tertiary amino group in the polyurethane resin is preferably 0.01 to 5.0 mmol /
g, more preferably 0.05 to 3.0 mmol / g. If the concentration is less than this, the dispersibility in the magnetic powder is not sufficient, the predetermined magnetic characteristics, the electromagnetic conversion characteristics cannot be obtained, and if the concentration is more than this, the urethane group concentration of the obtained polyurethane resin is It becomes high, it becomes difficult to dissolve in a solvent, and the solution viscosity becomes high.
Workability becomes poor in the steps of transfer and coating.

Specific examples of the sulfonic acid ester of the general formula (I) used in the present invention include methyl methanesulfonate, methyl benzenesulfonate, methyl p-toluenesulfonate, dimethyl acetonedisulfonate, and ethyl esters thereof. Compound, propyl ester compound,
Examples thereof include butyl ester compound, heptyl ester compound, hexyl ester compound, octyl ester compound, 2-methoxyethyl ester compound and phenyl ester compound. Among these sulfonates, methyl methanesulfonate, methyl benzenesulfonate and methyl p-toluenesulfonate are particularly preferable. The concentration of the sulfonic acid ester used in the polyurethane resin is preferably 0.01 to 5.0 mmol / g, more preferably 0.1.
It is 05-3.0 mmol / g. In this case, the concentration of the sulfonic acid ester used may exceed the concentration of the tertiary amino group, but it is more preferably within the range of not exceeding the concentration of the tertiary amino group.

The organic diisocyanates used in the present invention include tolylene diisocyanate and xylylene-
1,4-diisocyanate, xylylene-1,3-diisocyanate, 4,4'-diphenylmethane diisocineate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'- Diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-
4,4'-diisocyanate, 4,4'-diphenylpropane diisoanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-
1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3′-dimethoxydiphenyl-4,
Aromatic diisocyanates such as 4'-diisocyanate,
Aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate and lysine diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, cyclohexane diisocyanate and the like can be mentioned. These organic diisocyanates may be aromatic, aliphatic or alicyclic, and are selected according to the desired physical properties of the resin.

Other hydrophilic polar groups may be used in combination in the polyurethane resin of the present invention. For example, COOM group, O
H group, SO ₃ M group (M is hydrogen or alkali metal), P
It can be used in combination with an active hydrogen compound such as a diol, a diamine or an aminoalcohol having a hydrophilic polar group such as ═O (OM ′) ₂ group (M ′ is hydrogen, an alkali metal or a hydrocarbon group). Examples of the active hydrogen compound having a COOM group include COOM-containing glycols.
2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid, reaction products of diamines and acid anhydrides as examples of diamines, such as reaction products of isophoronediamine and phthalic anhydride. Can be mentioned.

As an example of the active hydrogen compound having an OH group, one secondary OH group-containing glycol is glycerin, an ethylene oxide adduct of glycerin, 1, 2,
There is a propylene oxide adduct of 6-hexanetriol and diethanolamine, and as a glycol having a tertiary OH group in the molecule, 1,2,3-hydroxy-
2-methylpropane, 1,3,5-hydroxy-3-methylpentane, 1,2,3,6-hydroxy-2,3-
A single substance or a mixture of dimethylhexane and the like, N-hydroxyethylethylenediamine, 1,3 as a diamine
-Diamino-2-propanol etc. can be mentioned.

Examples of the active hydrogen compounds having SO ₃ M groups include SO ₃ M group-containing glycols such as 2-sodium sulfo-1,4-butanediol and 2-potassium sulfo-1,4-butanediol, and 5 -Sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, sodium sulfosuccinic acid and the like can be mentioned.

Examples of active hydrogen compounds having a P = O (OM ') ₂ group are sodium 2,3-dihydroxypropyl-phenyl phosphonate, potassium bis (2-hydroxyethyl) phosphonate, bis- (4 -Hydroxybutyl) sodium phosphate etc. are mentioned.

Diols containing these hydrophilic polar groups,
The dicarboxylic acid, diamine or amino alcohol can be used as a part of the chain extender, but can also be used as a glycol raw material of the above-mentioned polyol. For example, as an initiator of a ring-opening polymerization reaction of a cyclic lactone monomer such as ε-caprolactone, an alkyl-substituted ε-caprolactone, δ-valerolactone, or an alkyl-substituted δ-valerolactone, or a dehydration condensation reaction with a known dicarboxylic acid or glycol. , Or a hydrophilic polar group-containing polyester polyol by the transesterification reaction with the above-mentioned polyester polyol, or a hydrophilic polar group-containing polyether polyol by using these compounds as an initiator during the production of the polyether polyol. ,
Further, by using these compounds as the polyhydric alcohol which is a raw material of the polycarbonate polyol, the hydrophilic polar group-containing polycarbonate polyol can be obtained. The polyol thus obtained can be used as a hydrophilic polar group other than the active hydrogen compound containing a tertiary amino group.

Each component constituting the polyurethane resin of the present invention has a molar ratio of a long-chain polyol and a chain extender to an organic diisocyanate (isocyanate group / hydroxyl group = R) of 0.50 to 1.10, preferably 0. It is manufactured as 80 to 1.05.

The binder thus obtained is linear and has hydroxyl groups at both ends, and has a number average molecular weight of 5,000 to
15,000, preferably 10,000 to 70,000
Is a polyurethane resin. When the molecular weight is less than 5,000, the dispersibility is excellent and advantageous, but the coating pattern forming ability is insufficient and the durability and the surface smoothness are poor. Molecular weight is 1
When it is more than 50,000, the dispersibility is lowered and the viscosity is increased, and the workability is lowered in the steps of mixing, transferring and coating in the production of the coating material.

When the polyurethane resin before quaternization according to the present invention is produced, a known bulk polymerization method in which the reaction is carried out in a molten state, or a ketone solvent such as methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, ethyl acetate or acetic acid is used. Ester solvent such as butyl, dioxane,
Ether solvents such as tetrahydrofuran, cellosolve,
Glycol ether type known as carbitol etc.,
Acetic acid glycol ether such as cellosolve acetate,
Dimethylacetamide, an amide solvent such as dimethylformamide, an aromatic hydrocarbon solvent such as toluene or xylene, an alcohol solvent such as methanol, ethanol, or isopropanol, or a mixture of the above components in a mixed solvent. A solution polymerization method in which the reaction is performed can be used.

Further, if necessary, a catalyst and a stabilizer can be used. Examples of the catalyst include nitrogen-containing compounds such as triethylamine and triethylenediamine, and organometallic compounds such as dibutyltin dilaurate, dioctyltin dilaurate, tin octylate and zinc stearate. As the stabilizer, an ultraviolet absorber such as a substituted benzotriazole, an antioxidant such as a phenol derivative, and a hydrolysis inhibitor can be added.

To the quaternary ammonium salt of the polyurethane resin containing a tertiary amino group produced as described above using a sulfonic acid ester, the required amount of the sulfonic acid ester is changed to a tertiary amino group. A method of adding to a polyurethane resin solution containing a group and stirring in a temperature range of room temperature to 80 ° C. for 1 to 100 hours can be mentioned. However, in the case of the tertiary amino group-containing polyurethane synthesized by the bulk polymerization method, a method of dissolving it in the above-mentioned solvent and performing quaternization can be mentioned.

In the present invention, the polyurethane resin of the present invention may be used together with other polyurethane resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol, which are usually used as a binder of a magnetic recording medium, if necessary. Type copolymer, polybutyl butyral type resin,
Thermosetting resins such as fibrin-based resins, polyester resins, epoxy resins and phenoxy resins, acrylonitrile-butanediene copolymer resins or reactive resins and unsaturated prepolymers such as urethane acrylic type, polyester acrylic type, or polyfunctional monomers. For example, a urethane acrylic type, a phosphoric acid ester acrylic type, an aryl type, or other electron beam or ultraviolet curable resin can be used in combination. COOM for these resins
Group, SO ₃ M group (M is hydrogen or an alkali metal), P =
Those containing a hydrophilic polar group such as O (OM ') ₂ group (M' is hydrogen, alkali metal or hydrocarbon group) are also included.

The magnetic powder used in the present invention includes, for example, γ-Fe ₂ O ₃ , Co-γ-Fe ₂ O ₃ and Co-Fe.
Iron oxide magnetic powder such as ₃ O ₄ , CrO ₂ , hexagonal barium ferrite fine particles, and Fe, Ni, Co, Fe-N
i-Co alloy, Fe-Mn-Zn alloy, etc. Fe, Ni, C
Various ferromagnetic powders such as metal magnetic powders containing o as a main component can be used. The polyurethane resin according to the present invention can be used in addition to magnetic recording media in addition to paints, adhesives, sealing agents, artificial leather,
It can be used for fiber treatment agents, elastic fibers, films and the like.

[0026]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, "part" and "%" are
"Parts by weight" and "% by weight" are shown unless otherwise specified. The composition of the long-chain polyol used is shown in Table 1.

[0027]

Example 1 A long-chain polyol A having a number average molecular weight of 2000 was placed in a reaction vessel equipped with a thermometer, a stirrer and a condenser.
[Polyester diol from glycol (ethylene glycol / neopentyl glycol = 1/1 molar ratio) and phthalic acid (isophthalic acid / terephthalic acid = 1/1 molar ratio) 1000 parts, neopentyl glycol 52.1
Parts, N-methyldiethanolamine 7.9 parts, cyclohexanone 883 parts and dioctyltin dilaurate 0.2 parts as a urethanization catalyst were charged and mixed at 50 ° C., and then 264.2 parts (R = 0) of 4,4′-diphenylmethane diisocyanate were added. .99) was added and reacted at 80 ° C. Since viscosity increases with time, dilute with cyclohexanone, methyl ethyl ketone and toluene at appropriate times,
It was confirmed by infrared spectrum that absorption of an isocyanate group at 2275 cm ^-1 disappeared, and a transparent pale yellow transparent liquid was obtained. Further, 12.3 parts of methyl p-toluenesulfonate was added, and the mixture was stirred at 50 ° C. for 10 hours. This polyurethane resin solution has a fixed content of 25.1% and a viscosity of 370 cP / 25.
Table 2 and 3 show the synthesized polyurethane resin composition having a number average molecular weight of 25,200, the solvent composition, and the characteristics, respectively.
Shown in.

[0028]

Examples 2 to 9 By the same synthesis method as in Example 1, the long-chain polyol, the chain extender, the organic diisocyanate, the active hydrogen compound containing a tertiary amino group and the sulfonate ester were synthesized in different kinds and amounts. . The synthesized polyurethane resin composition, solvent composition and properties are shown in Tables 2 and 3, respectively.

[0029]

Comparative Examples 1 to 5 By the same synthetic method as in Example 1, different kinds and amounts of the tertiary amino group-containing active hydrogen compound and the quaternizing agent were used for synthesis. Tables 2 and 3 show the synthesized polyurethane resin composition and characteristics, respectively.

[0030]

Comparative Example 6 N-methyldiethanolamine 16.1 was placed in a reaction vessel equipped with a thermometer, a stirrer and a condenser.
Parts, 25.1 parts of methyl p-toluenesulfonate and 41 parts of cyclohexanone were charged and mixed at 70 ° C. for 3 hours. Furthermore, the long-chain polyol A 10 used in Example 1
00 parts, neopentyl glycol 52.1 parts, cyclohexanone 842 parts and dioctyltin dilaurate 0.2 parts as a urethanization catalyst were charged and mixed at 50 ° C., and then 4,4′-diphenylmethane diisocyanate was added to 281.3 parts (R = 0. .99) was added and reacted at 80 ° C. Since the viscosity increases with time, it was diluted with cyclohexanone, methyl ethyl ketone and toluene at appropriate times, and it was confirmed by infrared spectrum that the absorption of the isocyanate group at 2275 cm ^-1 disappeared, and a transparent pale yellow transparent liquid was obtained. This polyurethane resin solution has a solid content of 25.3.
%, Viscosity 330 cP / 25 ° C., number average molecular weight 25,000
Met.

Evaluation of polyurethane film and magnetic layer

[0032]

[Application Example 1] Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a polyisocyanate curing agent was added to the polyurethane resin solution obtained in Example 1, and 10 parts of resin content was added to 100 parts of resin content and mixed for 1 hour Then, apply it on the release paper so that the dry film thickness is 100 μm, and
And dried for 2 hours to obtain a polyurethane film. The evaluation results of the moist heat resistance of this film are shown in Table 4. Further, using the polyurethane resin solution obtained in Example 1, a composition having the following mixing ratio was dispersed for 5 hours on a tabletop sand grind mill (manufactured by Igarashi Machinery Co., Ltd.), and Coronate L as a curing agent was added to the obtained magnetic paint. To 100 parts of resin content, add 10 parts of resin content and mix for 1 hour.
m of polyethylene terephthalate film so as to have a dry film thickness of 3 μm, immediately passed through a magnetic field of 2000 gauss for orientation treatment, and left standing at 60 ° C. for 24 hours to obtain a magnetic tape. Table 4 shows the measurement results of the glossiness and squareness ratio (Br / Bm) of the obtained magnetic tape.

Compounding composition for magnetic recording medium Magnetic powder (metal magnetic powder BET = 54 m ² / g) 100 parts Polyurethane resin (resin content) 20 parts MEK 110 parts Toluene 110 parts Cyclohexanone 74 parts

[0034]

[Application Examples 2-9, Comparative Examples 1-6] Instead of the polyurethane resin solution used in Application Example 1, the polyurethane resin solutions obtained in Examples 2-9 and Comparative Examples 1-6 were used. Moisture and heat resistance, dispersibility, and magnetic tape characteristics were evaluated with the same formulation. The results are shown in Table 4.

Evaluation Method Breaking Strength Retention Ratio: A polyurethane film was heated at a temperature of 7
The sample was stored at 0 ° C. and a relative humidity of 95% RH for 1 month, and the breaking strength before and after storage was measured using a Tensilon universal testing machine (manufactured by Toyo Baldwin) to determine the breaking strength retention rate and evaluate the moist heat resistance. Breaking strength retention rate (%) = breaking strength before storage / breaking strength after storage Gloss: The magnetic surface of the obtained magnetic tape was measured for reflectance at an incident angle of 45 degrees and a reflection angle of 45 degrees using a gloss meter. . Squareness ratio (Br / Bm): The electromagnetic conversion characteristics of the obtained magnetic tape were measured using a vibrating sample magnetometer VSM-3KA type (manufactured by Toei Industry Co., Ltd.).

[0036]

EFFECT OF THE INVENTION Since the polyurethane resin obtained by the present invention has high dispersibility and excellent storage stability, it is particularly suitable for video tapes, audio tapes, computer tapes, floppy disks, etc., which are required to have a high recording density. It is useful as a binder for magnetic recording media.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Explanation of Table 2 *]

[0040]

[Table 3]

[0041]

[Table 4]

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[Procedure amendment]

[Submission date] September 18, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

The organic diisocyanate used in the present invention includes tolylene diisocyanate, xylylene-
1,4-diisocyanate, xylylene-1,3-diisocyanate, 4,4'-diphenylmethane diisocineate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'- Diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-
4,4'-diisocyanate, 4,4'-diphenylpropane diisoanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-
1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3′-dimethoxydiphenyl-4,
Aromatic diisocyanates such as 4'-diisocyanate,
Aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, cyclohexane diisocyanate and other fats
Examples thereof include cyclic diisocyanate. These organic diisocyanates may be aromatic, aliphatic or alicyclic, and are selected according to the desired physical properties of the resin.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

The binder thus obtained is
It is linear and has hydroxyl groups at both ends, and has a number average molecular weight of 5,000 to 5,000.
It is a polyurethane resin of 150,000 , preferably 10,000 to 70,000. When the molecular weight is less than 5,000, the dispersibility is excellent and advantageous, but the coating pattern forming ability is insufficient and the durability and the surface smoothness are poor. Molecular weight is 1500
When it is more than 00, the dispersibility is lowered and the viscosity is increased, and the workability is lowered in the steps of mixing, transferring and coating in the production of the coating material.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

[0027]

Example 1 A long-chain polyol A having a number average molecular weight of 2000 was placed in a reaction vessel equipped with a thermometer, a stirrer, and a condenser.
[Polyester diol from glycol (ethylene glycol / neopentyl glycol = 1/1 molar ratio) and phthalic acid (isophthalic acid / terephthalic acid = 1/1 molar ratio) 1000 parts, neopentyl glycol 52.1
Parts, N-methyldiethanolamine (7.9 parts), cyclohexanone (883 parts) and dioctyltin dilaurate (0.2 parts) as a urethanization catalyst were charged and mixed at 50 ° C., and then 264.2 parts (4) of 4,4′-diphenylmethane diisocyanate (R = 0). .99) was added and reacted at 80 ° C. Since viscosity increases with time, dilute with cyclohexanone, methyl ethyl ketone and toluene at appropriate times,
It was confirmed by the infrared spectrum that the absorption of the isocyanate group at 2275 cm ⁻¹ disappeared, and a transparent pale yellow transparent liquid was obtained. Furthermore, methyl p-toluenesulfonate 12.3
Parts were added, and the mixture was stirred at 50 ° C. for 10 hours. This polyurethane resin solution has a solid content of 25.1% and a viscosity of 370 cP / 2.
It was 5 ° C. and the number average molecular weight was 25,200. Tables 2 and 3 show the synthesized polyurethane resin composition and characteristics, respectively.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

[0028]

Examples 2 to 9 By the same synthesis method as in Example 1, the long-chain polyol, the chain extender, the organic diisocyanate, the tertiary amino group-containing active hydrogen compound and the sulfonate ester were synthesized by changing the types and amounts. . Tables 2 and 3 show the synthesized polyurethane resin composition and characteristics, respectively.

Claims (2)

[Claims] 1. A polyurethane resin formed from a long chain polyol, a chain extender and an organic diisocyanate, wherein a part or all of the chain extender contains a tertiary nitrogen atom, and the tertiary resin in the polyurethane resin is further contained. A polyurethane resin binder for a magnetic recording medium, wherein a part or all of nitrogen atoms are quaternized with a sulfonate compound represented by the following general formula (I). R—SO ₃ —R ′ (I) (In the formula, R represents an alkyl group or aryl group having 1 to 12 carbon atoms, and R ′ represents an alkyl group having 1 to 8 carbon atoms.) 2. The polyurethane resin binder for a magnetic recording medium according to claim 1, wherein the sulfonate compound is selected from methyl methanesulfonate, methyl benzenesulfonate and methyl p-toluenesulfonate.