JPS61107531A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To form a magnetic recording medium having excellent magnetic powder dispersibility, the durability, surface smoothness, etc. of a magnetic layer by incorporating a urea bond into a polyurethane resin binder and incorporating a hydrophilic polar group therein. CONSTITUTION:The magnetic layer contains the polyurethane-urea resin having a COOM group (M is hydrogen or alkaline metal) and/or SO3M' type (M' is an alkaline metal) in the molecule. The high magnetic powder dispersibility and the excellent strength, durability coating property, etc. are thereby obtd. The cause for such remarkable improvement lies probably in the larger cohesive energy of the urea bond than the urethane bond and the generation of the physical crosslinking by the hydrogen bond between the urea bonds, by which the partial thermal motion of the molecular chain is immobilized by the cohesion of the urea bonds and the separation of the soft segment and hard segment of the resin is improved, thus exhibiting the excellent rubber elasticity. The softening point can be made higher than the softening point of the resin contg. of the urethane bond alone and therefore the smooth surface having the small coefft. of friction is probably obtd. when such resin is used as a binder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium in which a magnetic layer mainly composed of magnetic powder and a binder is formed on a non-magnetic support. This relates to improvements in agents.

Conventionally, binders made of various resins such as chloride-vinyl-acetate-vinyl alcohol copolymer, nitrocellulose, polyester resin, polyurethane resin, etc. alone or in combination have been used as magnetic recording media. With the expansion of applications, higher performance and higher density are required, and in the field of magnetic powder, the surface area is increased by making magnetic powder finer, and the magnetic powder is changed from iron oxide magnetic powder to alloy magnetic powder. Improvement is progressing rapidly.

Due to these factors, it is becoming difficult to sufficiently disperse magnetic powder using conventional binders because of the amplification of magnetic powder interaction due to an increase in surface area and an increase in coercive force.

In recent years, in order to improve these problems, binders have been developed that introduce hydrophilic polar groups into the binder to improve affinity with magnetic powder and enhance dispersion function. Although known binders have excellent magnetic powder dispersibility, they do not have satisfactory durability, and even though they have excellent durability, they have poor surface smoothness. No material has been obtained that satisfies all three requirements: dispersibility, durability of the magnetic layer, and surface smoothness of the magnetic layer.

Conventionally, polyurethane resin has been used as a magnetic recording medium because it has high elasticity and flexibility that cannot be obtained with other resins, has high strength and elongation, and has excellent wear resistance. In terms of Efforts have been made to improve the dispersibility of magnetic powder by introducing hydrophilic polar groups into the molecule to improve compatibility with magnetic powder, but these methods also improve the solubility of resin in solvents. , heat resistance, magnetic powder dispersibility, durability of the magnetic layer, surface smoothness, etc., have not been found yet.

The present invention has been made to solve these problems, and aims to provide a magnetic recording medium with excellent dispersibility of magnetic powder, durability of the magnetic layer, and surface smoothness. It is something.

As a result of extensive research, the present inventors have discovered that conventional drawbacks can be improved by introducing urea bonds and hydrophilic polar groups into polyurethane resin binders, leading to the present invention.

That is, the present invention provides a magnetic recording medium in which a magnetic layer mainly composed of magnetic powder and a binder is formed on a non-magnetic support, in which the magnetic layer has COOM groups (M is hydrogen or an alkali metal) and / or magnetic recording characterized by containing a polyurethane-urea tree 311 having SO, M' groups (M' is an alkali metal) as a binder), 1. A medium, and the polyurethane-urea resin and the polyisocyanate compound. The present invention relates to a magnetic recording medium characterized in that it contains a reactant as a binder.

To explain in more detail, organic diamine and/or water and/or urea (NH, CONH,) are used as part of the active hydrogen compound as a binder, and the urea bond (- NHCONH-) and a COOM group introduced from a hydrophilic polar group-containing compound (M is hydrogen or an alkali metal) and/or 'tt So, M'
By simultaneously introducing a hydrophilic polar group (M' is an alkali metal) into the molecule, high magnetic powder dispersibility, excellent strength, durability, and coatability can be obtained, and this drastic improvement has been achieved. The reason for this is that urea bonds have a larger cohesive energy than urethane bonds, and physical crosslinks occur between urea bonds due to hydrogen bonds, and the aggregation of urea bonds fixes the thermal motion of partial molecular chains, resulting in soft segments of the resin and It is thought to have good separation of hard segments and exhibit excellent rubber elasticity, and its softening point can be higher than resins with only urethane bonds, so when used as a binder, it has a smooth surface with a low coefficient of friction. It is thought that it is possible to obtain.

Particularly surprisingly, the urea bonds obtained from water and/or urea can have a shorter repeating bond interval than the urea bonds introduced from organic diamines and organic diisocyanates represented by H, NRNH, and as a result, the urea bonds can be concentrated. This means that stronger hydrogen bonding force can be obtained.

The organic diisocyanates used in the production of the polyurethane-urea resin in the present invention include 2.4-)lylene diisocyanate, 2.6-1-lylene diisocyanate, P-phenylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate), 3.3'-dimethoxy 4.4'
-biphenylene diisocyanate, 2,4-naphthalene diisocyanate, 3,31-dimethyl-4,4'-biphenylene diisocyanate, 4,4'-diphenylene diisocyanate, 4,4'-diisocyanate-diphenyl ether, 1.5-naphthalene diisocyanate, P-medium silylene diisocyanate, m-xylylene diisocyanate, 1.3-diisocyphnate methylsif-hexane, 1,4-diincyanate methylcyclohexane, 4,4'-diisocyanate dicyclohexane , 4,4'-diisocyanate dicyclohexylmethane, inphorone diisocyanate, etc., and these can be used alone or as a mixture of two or more. Diisocyanates obtained by modifying the incyanate with a polyol or the like can also be used in the same manner.

As dihydroxy compounds used in the present invention, polyester diols, polyether diols, and short chain glycols are used, and specific examples of polyester diols include snolylic acid, adipic acid, sebacic acid, azelaic acid, etc. aliphatic dicarboxylic acids, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, or their lower alkyl esters, ethylene glycol, 1,3-bupylene glycol, 1,4-butylene glycol, 1,6-hexane Polyesters obtained by reacting gelyl, diethylene glycol, neopentyl glycol, ethylene oxide adducts of bisphenol A, etc., or mixtures thereof; ring-opening polymerization of diols or lactones such as ε-cablockone; Examples include the obtained lactone-based polyester diols. Examples of the polyether diol include polyethylene glycols such as polyethylene glyfur, polypropylene ether glycol, and polytetramethylene ether glycol, and copolymerized polyether glycols thereof. Examples of polyether ester glycols include polyester glycols obtained by reacting the above polyalkylene ether glycol with an aliphatic or aromatic dicarboxylic acid as a polyol component, and short-chain glycols include polyester glycols. Glyfurs listed as raw materials for diols can be used.

In addition, the organic diisocyanate and the anti-
Compounds that generate urea bonds accordingly include organic diamines and/or water and/or urea, and examples of organic diamines include aliphatic diamines such as tetramethylene diamine and hexamethylene di-7Z, and m-phenyl diamines. Aromatic diamines such as 22-diamine, P-phenylene diamine, 2,4-)lylene diamine, 2,6-lylene diamine, 4,4'-biphenylene diamine, 1,5-naphthalenediamine, 1. 3-diaminomethylcyclohexanone, 1.4-diaminomethylcyclohexanone, 4.
Examples thereof include alicyclic diamines such as 4'-di7minodisikkhohesylmethane and inphorondiamine.

Water reacts with isocyanate groups to produce amino groups, as shown in 2).

R-NCO+H, O→R-NH, + Co,
(1) Furthermore, in the present invention, a hydrophilic polar group such as a COOM group (M is hydrogen or an alkali metal) and/or a SO□M' group (M' is an alkali metal) is introduced into the polyurethane-urea resin. The polar group-containing compound may be either a dihydroxy compound or a diamine compound, but for example, if SO,M' group is introduced as a dihydroxy compound, for example, (m, L is 0 to 20), M' is an alkali metal] by using Glyfur containing SO, M' group as a short-chain diol, or as an initiator for Glyfur as a raw material for polyester diol or for polyether diol or polycarboxylic acid diol. It is possible to introduce hydrophilic polar groups into the diol or polycaprolactone diol.

Other introduction methods include 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 2-sodium sulfoisophthalic acid, 2-potassium sulfoisophthalic acid, and It is also possible to use sodium sulfosuccinate and the like.

In addition, diamine compounds having SO, M' groups (M' is an alkali metal) include diaminotoluenesulfonic acid metal salts, naphthylenediaminesulfonic acid metal salts, etc., and when used as a chain extender, 801 M' It is possible to introduce groups.

Similarly, COOM groups can be introduced into the structures of polyester diols, polyether diols, and polycaprolactone diols in the same manner as the introduction of dimethylolpropylene or SO,M' groups.

Preferred alkali metals in these compounds include potassium and sodium.

These polyurethane-urea resins are produced by melt polymerization, which involves reacting them in the molten state, using methyl ethyl ketone, toluene,
Solution polymerization is carried out by dissolving each of the above-mentioned raw materials in an inert solvent such as cyclohexane, dimethylformamide, tetrahydrofuran, etc. alone or in combination.

During the reaction, an organic metal compound such as diptyltin dilaurate, or a tertiary amine such as N-methylmorpholine or triethylamine may be added as a catalyst. Further, in order to increase the stability of the resin, antioxidants, ultraviolet absorbers, hydrolysis inhibitors, etc. may be added.

The urethane group concentration in the polyurethane-urea resin obtained in this way has a large effect on solubility, and varies depending on the type of organic diisocyanate, type of dihydroxy compound, molecular weight, etc., so it cannot be generalized, but urethane If the group concentration exceeds about 2.0 m mol/g, it tends to be difficult to dissolve in ketone, ester, or aromatic solvents, but in this system, for example, if the urethane bond concentration is 2.0
Surprisingly, even if the urea bond concentration is fixed at mmol/g and increased, the solubility does not decrease, and physical properties such as Young's modulus and softening point can be further improved.

This effect is particularly remarkable when water and/or urea are used as chain extenders.

Furthermore, by introducing urea bonds, which have a higher cohesive energy than urethane bonds, it is possible to obtain a tough film that is harder than conventional urethane-based films that do not contain urea bonds. In addition, since the urea bond is a weakly hydrophilic group, it also contributes to improving dispersibility, and the COOM group, 505M! It was found that the simultaneous presence of a hydrophilic polar group such as a hydrophilic polar group has a more favorable effect on dispersibility.

This optimal urea bond concentration varies depending on the molecular weight of the polyol and cannot be determined unconditionally, but if there are too many urea group bonds, the resulting polyurethane-urea resin will lack the flexibility required as a binder. The upper limit is preferably set to 2.0 mmol/g,
On the other hand, if there are few urea bonds, the softening point will be low like conventional urethane resins, the surface smoothness will be poor, and blocking resistance will be improved, and the lower limit of flaws is 0.1 mmol.
It is preferable to set it to /g.

In addition, the molecular weight of the polyurethane-urea resin is preferably 8,000 to 50,000 from the viewpoint of durability and operability. If it is less than 5,000, the viscosity of the paint is low, so it can be highly solidified. Although it has advantages, it has poor physical properties and poor durability. On the other hand, if it is 100,000 or more, the durability is good, but when it is made into a paint, it has a high viscosity and requires a long time for dispersion, and the processability during coating is poor and the surface smoothness cannot be improved.

Furthermore, C which is a hydrophilic polar group to be introduced into the binder of the present invention
The content of OOM groups and SO,M' groups is about 0.
A suitable range is 0.01 to 1.0 mmol/g, more preferably a range of 0.02 to 0.5 mmol/g.

If the hydrophilic polar group concentration is less than 0.01 mmol/g, no sufficient effect on dispersibility will be observed.

Furthermore, if the concentration of the hydrophilic polar group exceeds 1.0 mmol/g, aggregation tends to occur between or within molecules, resulting in an increase in the viscosity of the magnetic paint or aggregation, which not only adversely affects dispersion, but also If the solubility in solvents decreases and it becomes insoluble in commonly used solvents, making it impossible to use it as a binder, or if the magnetic layer is used with a binder whose concentration of hydrophilic polar groups exceeds the above-mentioned upper limit. When formed, the hydrophilicity is too strong, resulting in decreased moisture resistance and severe deterioration during long-term storage or under high temperature and high humidity, making it unsuitable as a magnetic recording medium.

In addition, the above polyurethane-urea resin may be used with other thermoplastic resins,
It can be used in combination with thermosetting resins or reactive resins. In this case, the blending ratio of the polyurethane-urea resin to the total binder of the magnetic layer is preferably 5% by weight or more. If the blending ratio of the polyurethane-urea resin to the total binder is less than 5% by weight, hardly any improvement in the blocking resistance of the magnetic recording medium can be expected. Examples of the above-mentioned thermoplastic resin include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-7-crinitrile copolymer, Polymer, thermoplastic polyurethane elastomer, polyhinyl polyfluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-7 clinitrile copolymer, polyamide resin, polyvinyl butyral,
Examples include synthetic rubber-based thermoplastic resins such as cellulose, dielectrics, polyester resins, and polybutadiene.

In addition, examples of thermosetting resins or reactive resins include:
Phenol resin, epoxy resin, polyurethane curable resin, melamine resin, alkyd resin, silicone resin, acrylic reaction resin, epoxy-poly7mide resin, nitrocellulose-melamine resin, mixture of high molecular weight polyester resin and incyanate prepolymer, mixture of methacrylate copolymer and diisocyanate prepolymer,
Examples include mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glyco/high molecular weight diols/triphenylmethane triisocyanate, polyamine resins, and mixtures thereof.

A magnetic layer is formed by dispersing ferromagnetic powder in the above-mentioned binder, dissolving it in an organic solvent, and coating it on a nonmagnetic support.

Further, in addition to the binder and magnetic powder described above, additives such as a dispersant, a lubricant, an abrasive, an antistatic agent, and a rust preventive may be added to the magnetic layer.

Examples of the dispersant (pigment wetting agent) include caprylic acid, capric acid, lauric acid, myristic acid, valmitic acid, stearic acid, oleic acid, and linau acid.

Fatty acids with 12 to 18 carbon atoms (R
IC00H%R1 is a fulkyl or alkenyl group having 11 to 17 carbon atoms), a fulkali metal of the above fatty acid (Li
%Na%) or alkaline earth metals (MgtCa% etc.) or alkaline earth metals (MgtCa% etc.)
sBa), fluorine-containing compounds of the above fatty acid esters, 7mide of the above fatty acids, polyfulkylene oxide alkyl phosphate esters, trialkyl polyoleaine oxy quaternary ammonium salts (alkyl has 1 carbon number) ~5 olefins, ethylene, propylene, etc. are used. In addition to these, higher alcohols having 12 or more carbon atoms and sulfuric esters can also be used. These dispersants are added in an amount of 0.15 to 10 parts by weight per 100 parts by weight of the magnetic powder.

The above-mentioned lubricants include difurkylpolysiloxane (alkyl has 1 to 5 carbon atoms), dialco-cyclosilexane (alkoxy has 1 to 4 carbon atoms), monoalkyl monoalf Φ siborisiloxane (alkyl has 1 to 4 carbon atoms), ~5 pieces,
Alkoxy has 1 to 4 carbon atoms ([), phenyl polysiloxane, fluorocarbon polysiloxane (alkyl has 1 to 5 carbon atoms), silicone oil, conductive fine powder such as graphite, molybdenum disulfide, disulfide Fine inorganic powders such as tungsten, fine plastic powders such as polytetrafluoroethylene, α-olefin polymers, unsaturated aliphatic hydrocarbons that are liquid at room temperature, monobasic fatty acids with 12 to 20 carbon atoms and 3 carbon atoms. Fatty acid esters consisting of ~12 monohydric alcohols, fluorocarbons, etc. can be used.

These lubricants contain 0.00% per 100 parts by weight of magnetic powder.
It is added in an amount of 2 to 1 oot part. The above-mentioned abrasives include commonly used materials such as fused alumina, silicon carbide, chromium oxide (CrtOx), corundum, artificial frundum, diamond, artificial diamond, garnet, emery (main components: frundum and magnetite), etc. is used. These abrasives are added in an amount of 0.5 to 20 parts by weight per 100 parts of magnetic powder.

Examples of the antistatic agent include conductive fine powders such as carbon black and carbon black grapho polymer, natural surfactants such as saponin, nonionic surfactants such as fullkylene oxide, glycerin, and glycidol,
Higher alkylamines, quaternary ammonium, salts, pyridine and other heterocycles, cationic surfactants such as phosphoniums, carboxylic acids, sulfonic acids, phosphoric acids, 1 liter
Anionic surfactants containing acidic groups such as Efl ester groups and phosphate ester groups, amino acids, 7-minosulfonic acids, and ampholytic surfactants such as sulfuric acid or phosphoric esters of aminofluor are used. The above conductive fine powder is added in an amount of 0.2 to 20 parts by weight, and the surfactant is added in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the magnetic powder. These surfactants may be added alone or in combination. These are used as antistatic agents, but
Sometimes for other purposes, e.g. dispersion, improving magnetic properties,
It is sometimes used to improve lubricity and as a coating aid.

As the rust preventive agent, phosphoric acid, sul-77mide, guanidine, pyridine, amine, urea, zinc coumamate, calcium chromate, stonetium chromate, etc. can be used.

These rust inhibitors are 0.01 parts by weight per 100 parts by weight of magnetic powder.
It is used in a range of 2.0 parts by weight.

In addition, the constituent material of the magnetic layer is dissolved in an organic solvent to prepare a magnetic paint, and this is coated on a non-magnetic support.The solvent for the magnetic paint may be acetone, methyl ethyl ketone, methyl imbutyl ketone, cyclohexanone, etc. Ketones, methyl acetate, ethyl acetate, butyl acetate, ethyl lactate,
Ester types such as acetic acid glyfur monoethyl ether, glycol dimethyl ether, glyfur monoethyl ether, glycol ether types such as dioxane, aromatic hydrocarbons such as benzene, toluene, xylene, etc.
Examples include aliphatic hydrocarbons such as heptane, chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and dichlorobenzene.

Furthermore, when a polyisocyanate compound is used in combination with the above-mentioned polyurethane-urea resin as a curing agent, a magnetic recording medium with excellent wear resistance can be obtained.

In addition, examples of the polyisocyanate compound used as a curing agent include Butyonate L1 Coronadeto HL, Coronate EH, Coronate 2030.20N) 303
0, Fronate 4048, Coronat 4190, Fronate 4192 (all manufactured by Nippon Polyurethane Industries), etc. can be used.

Further, the amount of the polyisocyanate compound may be any amount that is normally used, and may be 3 to 30 parts by weight (in terms of solid content) per 100 parts by weight of the total amount of the polyurethane-urea resin and other resins. Within range.

Materials for the nonmagnetic support include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polyethylene and polypropylene, cellulose triacetate, cellulose diacetate, and cellulose diacetate petit. It is used in addition to plastics such as cellulose derivatives such as cellulose chloride, cellulose derivatives such as cell p-acetate propionate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, polycarbonate, polyimide, poly7mide, and imide. Non-magnetic metals such as aluminum, copper, tin, zinc or non-magnetic alloys containing these, ceramics such as glass, pottery and porcelain, paper, baryta or polyethylene, polypropylene, ethylene-butene copolymers, etc. Paper such as paper coated or laminated with α-polyolefin a having 2 to 10 carbon atoms can also be used. The nonmagnetic support may be in any form such as a film, tape, sheet, disk, card, or drum.

By using the binder according to the present invention, the dispersibility of the magnetic powder is improved, the magnetic properties such as the square disc ratio Rs1 and the saturation magnetic flux density Bm are excellent, and the durability of the magnetic layer can be improved, and the still Characteristics such as level fluctuation output attenuation due to time and powder fallout are improved, and the surface smoothness of the magnetic layer can also be improved, so electromagnetic conversion characteristics such as frequency characteristics, S/
Characteristics such as N ratio can also be improved.

This will be explained in more detail with reference to Examples below.

"Parts" and "%" in the examples are "parts by weight" and "% by weight" unless otherwise specified.

Production Example 1 of Polyester Polyol Containing Hydrophilic Polar Groups 484 parts of adipic acid, 459 parts of 1,6-sangrifur, 176 parts of 5O1Na group-containing compound'), catalyst in a reactor equipped with a thermometer, stirrer and condenser. Add 0.3 parts of zinc acetate and 0.04 parts of sodium acetate as 1
The normal pressure esterification reaction is carried out at 40°C to 220°C, and when the predetermined reaction rate is reached, the reaction system is depressurized at a rate of 100 mHg/30 minutes, and after 4 hours, the pressure is reduced to 20 mHg, and the esterification is maintained at that vacuum level for 1 hour. The reaction was carried out to obtain a polyester polyol containing 5OINa groups. The obtained polyol has a hydroxyl value of 102 and an acid value of 0 as shown below.
．． 6, SO, Na group concentration 0.42 mmol/g Example 2゜Example 1. In a reactor similar to the above, 8 parts of neopentyl glycol 216M5.1.4-butylene glyco'-lua, 1
．． 245 parts of 6-hexane glycol, 165 parts of sodium dimethyl sulfosuccinate, and 0.5 parts of zinc acetate as a catalyst.
3 parts, add 0.04 part of sodium acetate to 140-180
After carrying out the demethanol transesterification reaction at ℃, 489 parts of 7-divic acid was added and the temperature was raised to 210 to 240 ℃ to form a polyester through a dehydration reaction, followed by the same reduced pressure reaction as in Example 1 to obtain a product containing 5O1Na groups. A polyester polyol was obtained. The obtained polyol had a hydroxyl value of 110, an acid value of 0.8, an SO3Na group concentration of o, a of 4 mmol/g, as shown below.Example 3゜Polybutylene adipate (
Molecular weight 2.000') 2. Add 0 parts of OO, 134 parts of dimethylolpropionic acid, and 0.3 parts of titanium acetyl 7cetonate as a transesterification catalyst, 140-1
Heat and stir at 80°C for 8 hours to form 1; C0OH in the side chain.
A polyester polyol containing groups was obtained. The obtained polyol has a hydroxyl value of 106 and C0O as shown below.
H group concentration 0.469 mmol/g Example 4゜ To 1,000 parts of the C0OH group-containing polyester polyol obtained in Example 3, add 10% aqueous solution of caustic soda necessary to neutralize 95% of C0OH, and add C0OH. After neutralization, the mixture was dehydrated under reduced pressure at 150° C. and 20 mHg for 2 hours to obtain a COONa group-containing polyester polyol. The obtained polyol has a hydroxyl value of 106, as shown below.
Acid value Q, 2 COONa group concentration 0.445 mmol/g Actual, Examples 5 to 7゜ In the same reactor as in Example 1, raw materials in the proportions shown in Table 1 were used, and 0.05% zinc acetate was used as a catalyst. An esterification reaction was carried out in the same manner as in Example 1 using 0.007 parts of sodium acetate to obtain the polyester polyols shown in Table 1.

Below is a blank table. 1 Sodium dimethyl sulfoisophthalate 2) Comparative example Production of polyurethane-urea resin Example 8 In a reactor equipped with a thermometer, a stirrer, and a condenser, the SO, Na group-containing mixture obtained in Example 1 was added. 36.0 parts of polyester polyol, polyhexamethylene adipate (molecular weight 1
000) 200.0 parts, 69.9 parts of 4.4'-di72nylmethane diinsinocinate (hereinafter abbreviated as MDI) and 306 parts of methyl ethyl ketone (hereinafter abbreviated as MEK) were added and reacted at 70 to 80°C for 3 hours LNCO A prepolymer was obtained.

Next, in order to proceed with the ureation reaction, 0.84 parts of water and 1.0 part of triethylamine were added as a ureation catalyst, and an additional 75 parts of water was added.
The reaction proceeded at ~80°C. When the viscosity reached approximately 500,000 cps/25°C, the remaining N was diluted with MEK to a solid content of 30%.
Monoethanolamine corresponding to the GO concentration was added to terminate the reaction by OH-terminating it. The obtained resin A was as follows: Appearance: pale yellow and transparent Solid content: 30% Viscosity: 5000 cps 725°C Examples 9 to 13 The S 03 obtained in Example 1 was placed in the same reactor as Example 8.
A resin was produced by changing the SO3Na group concentration of the polyurethane-urea resin under the same conditions as in Example 8, except that the ratio of Na group-containing polyester polyol and polysameethylene 7 dibate (molecules, [1000'') was changed. The resulting resin is shown in Table 2.

Table, 2 □ 1) Solid content 35% 2) Comparative Example Example 14 In a reactor similar to Example 8, the C0OH group-containing polyester polyol obtained in Example 3 (hydroxyl value 106, C0O
H group concentration 0.469 mmol/g) 533 parts, neopentyl glycol 52 parts, MDI 375 parts and ME
K640 parts, dibutyltin dilaurate 0.2 as catalyst
After 3 hours of reaction at 70 to 80° C., 9.0 parts of water was added to proceed with the urea reaction.

When the viscosity reached approximately 500,000 cpa/25° C., it was diluted to a solid content of 30% with MEK/cyclohexanoso=3/71,600 parts.

The residual NCO concentration was 0.010 mmol/g.

2.0 g of monoethanolamine having an NH group corresponding to this NGO was added to form a terminal OH group to terminate the reaction. The obtained resin G is as follows: Appearance: Light yellow and transparent Solid content: 30% Viscosity: 10,000 cp 725°C Example 15 (Comparative example) In Example 14, the same mole of 1,4-butylene glycol was substituted for water. Add 45 parts and extend by urethanization reaction to C0
This was designated as OH group-containing urethane resin H.

The second resin solution had poor liquid properties and was a turbid liquid, but after a few days it became agar-like and had poor storage stability.

Appearance Milky white opaque solid content 30% Viscosity 15000 cps/2s°C (immediately after production) Examples 16 to 22 Using a stainless steel beaker, the polyester polyol obtained in Example 6 (hydroxyl value 56, S 03 Na group concentration 0.42) mmol/g) and the polyester polyol obtained in Example 7 (hydroxyl value 56, SO, Na group concentration 0)
) and 1,4-butylene glycol, isophorone diisocyanate, and urea at different molar ratios (see Table 3), and mixed for about 1 minute at 70°C with a tabletop stirrer (2000°C).
r, p, m) was carried out, and then the reaction mixture was poured into a vat heated to 110°C for 1 hour, and then kept at 100°C for 20 hours to complete the reaction. Table 3 shows the obtained polyurethane-urea resin.

Example 23 In a reactor similar to Example 8, the polyester polyol obtained in Example 2 (hydroxyl value 110, acid value 0.8.5O1N) was added.
a group concentration 0.64 mmol/g) 100 parts and polyethylene diethylene adipate (molecular weight 1000)
4oofi6 and trilene di incyanate (hereinafter referred to as TDI)
) and 630 parts of MEK were added at 80°C.
After reacting for an hour, add 315 parts of Nakasanone to the cyclo and solid content 4
It was set to 0%.

After cooling to room temperature, 42 parts of inphorondiamine was added to MEK42.
It was added as a solution dissolved in 0 parts and allowed to react. When the viscosity reaches approximately 4000 cps/2s℃, add acetic acid and remove the remaining 7.
The reaction was stopped by neutralizing the i.n. The obtained resin Q is as follows: Appearance: pale yellow, slightly cloudy, solid content: 33%, viscosity: 400
0 cps/2s°C, Example 24:
In a reactor similar to Example 8, the polyester polyol obtained in Example 3 (hydroxyl value 106, C0OH group concentration 0.4) was added.
After dissolving 160 parts of 69 mmol/g), 1125 parts of polycaprolactone polyol (molecular weight 1250), and 45 parts of urea in 1772 parts of MEK, MDI442
500,000 cps/25
When the temperature reached °C, the mixture was diluted with cyclohexanone to give a solid content of 30% to obtain a COOH group-containing polyurethane-urea resin R. The obtained resin R was as follows: Appearance: pale yellow and transparent Solid content: 30% Viscosity: 3500 cp@/25°C Example 25 The same reactor as Example 8 was used, except that the polyester polyol of Example 4 was used. COON under the same conditions as Example 24
A group-containing polyurethane-urea resin S was obtained. The obtained resin S is as follows: Appearance: pale yellow and transparent, solid content: 3
0% Viscosity 4500 cps/25°C Example 26 In a reactor similar to Example 8, TDI (T-80) 26
1 part dimethylol bupionic acid and 7 parts M E K
2681H5 was added and reacted at 80° C. for 3 hours to obtain a modified TDI solution containing a C0OH group concentration of 0.09 mmol/g. Next, 250 parts of MEKl and 1250 parts of polybutylene adipate (molecular weight 1000) were added to cause a polymerization reaction, and 3.6 parts of water and 8 parts of triethanolamine were added to cause a urea reaction. A polyurethane-urea resin T containing terminal OH groups and C0OH groups was obtained. The obtained resin T was as follows: Appearance: Pale yellow transparent solid content: 35% Viscosity: 8000 cps/2s°C Example 27 Using the same reactor as in Example 8, hexamethylene diamine was added in place of water in Example 26. A COOH group-containing polyurethane-urea resin U was obtained in the same manner except that 23.3 parts were used. The obtained resin U was as follows: Appearance: pale yellow liquid, solid content: 35% Viscosity: 12000 CpS/25°C Example 28 Polybutylene 7 dipate (molecular weight: 1
00G) in place of 1250 parts of S OsN in Example 1
The same conditions as in Example 26 were used, except that 100 parts of a group-containing polyester and 1150 parts of polybutylene adipate (molecular weight 1000) were used, and 6 parts of urea and 1.8 parts of water were used instead of 3.6 parts of water. , 5OINa group, and COOH group-containing polyurethane-urea resin V was obtained. The obtained resin V has the following appearance: light yellow and transparent, solid content: 35 parts, viscosity: s o o o cps/2s°C Table 4 shows the urethane bond concentration, urea bond concentration, hydrophilic polar group concentration, etc. of the various resins. .

Creation of clear film The resin solutions obtained in Examples and Comparative Examples were used as they were, and a polyisocyanate compound (Coronet L) was added to the resin solutions at a ratio of 10 parts (in terms of solid content) per 100 parts of resin. The two types were coated on release paper using a knife coater to a dry film thickness of 100μ, and left at room temperature for 30 minutes.
A film was obtained by curing and drying at 80° C. for 15 minutes and at 120° C. for 15 minutes. (However, the resin symbol ~P is MEK / cyclohegosan = 30% solid content) Physical properties of clear film Glass transition point (Tg) Clear film was measured using a dynamic viscoelasticity measuring device (DDV-II =
EA, manufactured by Toyo Baldwin) at 110H2.2℃/
Measured under min conditions, T
It was set as g.

Softening point (SP) Cut the clear film with a JI52 dumbbell and apply a load of 5
Attach a weight of g / 100μ, temperature increase rate 10℃ /
SP at the final elongation temperature of the film under min conditions.
And so.

Durability The retention rate of the tensile strength at break (TB) after 2 weeks under high temperature conditions (70° C. x 95% RH) was used as an index of durability.

TB retention rate (%) ◎ 90 or more Q 70-89 Δ 50-69 X SO or less Polyurethane-urea resin obtained in magnetic coating examples and comparative examples
100Co-1-Fe mountain (Hc 6500"e, BET
32 m”/g) 400 torr/MEK/hexanon = 3/3/2 9 a.

The magnetic paint obtained by dispersing the magnetic coating material in a ball mill for 48 hours was coated on a polyethylene terephthalate film with a thickness of 15 μm to a dry film thickness of 5 μm, and its magnetic properties were measured.

Glossiness A 60' to 60' reflective gloss rate was measured using a gloss needle (gloss meter, manufactured by UGV-5G Suga Test Instruments).

Tack: Judgment was made by measuring the surface roughness and coefficient of dynamic friction using a surface smoothness measuring device (HEIDON1 manufactured by Shinto Kagaku).

Judgment was made from wear waves using a durability abrasion tester (taper abrasion tester).

Display of measurement results ◎　Excellent　　　Good Δ Possible × Not possible Table 5 shows the physical property measurement results of various resins.

Margin table below, 4 1) Comparative example 2) 503 Nm group 3) COOH! 1) COONi S) 503 Nm group 0.028 mmol/g and C0
OH group 0. o 33 mmol/g Concentrations in the table are based on 100% solid content. 5 1) Added polyisocyanate compound (curing agent).

,−

Claims (2)

[Claims] (1) In a magnetic recording medium in which a magnetic layer mainly composed of magnetic powder and a binder is formed on a non-magnetic support, the magnetic layer has a COOM group (M is hydrogen or an alkali metal) and/or A magnetic recording medium comprising a polyurethane-urea resin having an SO_3M' group (M' is an alkali metal) as a binder. (2) In a magnetic recording medium in which a magnetic layer mainly composed of magnetic powder and a binder is formed on a non-magnetic support, the magnetic layer has a COOM group (M is hydrogen or an alkali metal) and/or A magnetic recording medium characterized in that it contains a reaction product of a polyurethane-urea resin having an SO_3M' group (M' is an alkali metal) and a polyisocyanate compound as a binder.