JPH05171071A - Magnetic coating material - Google Patents

Abstract

PURPOSE:To obtain a magnetic coating material which is excellent in the dispersibility of a magnetic powder and can give a magnetic recording medium excellent in surface smoothness, durability, abrasion resistance, etc., by using a specified block copolymer comprising a polyurethane segment and a vinyl polymer segment as a binder. CONSTITUTION:The title material consists essentially of a block copolymer comprising a polyurethane segment and a vinyl polymer segment and containing -SO3X and/or -COOX groups (wherein x is a quat. ammonium group) and a magnetic powder.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel and useful magnetic coating material. More specifically, a block copolymer obtained by polymerizing at least one polymerizable unsaturated monomer in the presence of a specific compound having both a diazo bond and a urethane bond in the main chain, and a magnetic The present invention relates to an extremely highly practical magnetic coating material containing powder as an essential component.

Such a novel form of the magnetic coating material of the present invention exerts an epoch-making effect especially for magnetic recording media such as magnetic tapes, magnetic cards and magnetic disks.

[0003]

2. Description of the Related Art In recent years, with advances in hardware technology such as 8 mm video in audiovisual, DAT or S-VHS, remarkable progress in hardware in computers, and high density recording media,
The performance requirements for audio tapes, household VTR tapes, magnetic tapes for computers, and floppy disks are becoming more sophisticated.

In particular, there is a demand for high reliability in recording / reproducing, and in particular, in video tapes, in addition to high reliability, high image quality in recording / reproducing is required. Specifically, not only high recording density for reproducing clear images and sound, capable of withstanding high-speed long-time running under severe conditions such as high temperature and high humidity, and It is demanded that the magnetic powder of the above does not fall off.

It is an important function of the binder to maintain the properties or physical properties of the magnetic layer, and the excellent dispersibility of the magnetic powder, high sensitivity, high SN ratio and high CN ratio. In view of the above, it is required that excellent electromagnetic characteristics can be obtained, and in addition, durability such as wear resistance and wet heat resistance is excellent.

[0006] Various binders have been studied so far in order to satisfy such various physical properties, and the magnetic layer is provided with good abrasion resistance to improve the durability of the magnetic recording medium. For the main binder for
A blend of a vinyl acetate copolymer and a polyurethane resin has been used.

However, depending on the degree of compatibility between the vinyl chloride-vinyl acetate copolymer and the polyurethane resin, the dispersibility of the magnetic powder, the surface smoothness of the obtained magnetic recording medium, the durability, etc. may become poor. The reality is that many things that can be fully satisfied have not yet been obtained.

[0008]

Therefore, the inventors of the present invention stand on the basis of the recognition of the present situation, the drastic solution of various unsolved problems in the prior art, and the urgent demand in the industry. As a result of extensive studies, at least one general formula in one molecule

[0009]

[Chemical 7]

(Wherein R ₁ is an alkylene group, a cyclic alkylene group, an alkylene group having an ester group, a benzene ring or an alkylene group containing a benzene ring,
R ₂ and R ₂ 'are each an alkylene group, an alkylene group containing a cyano group, an alkylene group containing an amide bond, or an alkylene group having both an amide bond and a hydroxyl group, which may be the same or different. Shall be represented. ) Structural unit, that is, the diazo bond and the general formula

[0011]

[Chemical 8]

(In the formula, R ₃ represents a polyol residue.) In the presence of a structural unit, ie, a compound having a urethane bond, at least one type of polymerizable unsaturated -S obtained by polymerizing monomers
A block copolymer containing an O ₃ X group and / or a —COOX group (provided that X represents a quaternary ammonium group) is used for the dispersibility of the magnetic powder, the surface smoothness of the magnetic recording medium, and the durability. The present invention has been completed here by finding that it can provide a magnetic coating material having excellent wear resistance and the like.

[0013]

Means for Solving the Problems That is, the present invention newly comprises a block copolymer having a polyurethane segment and a vinyl polymer segment, and a magnetic powder as essential components, respectively. It aims to provide useful magnetic paints,
At least one general formula in a molecule

[0014]

[Chemical 9]

(Wherein R ₁ is an alkylene group, a cyclic alkylene group, an alkylene group having an ester group, a benzene ring or an alkylene group containing a benzene ring,
R ₂ and R ₂ 'are each an alkylene group, an alkylene group containing a cyano group, an alkylene group containing an amide bond, or an alkylene group having both an amide bond and a hydroxyl group, which may be the same or different. Shall be represented. ) And the general formula

[0016]

[Chemical 10]

(Where R ₃ in the formula represents a polyol residue) and a compound having a number average molecular weight of 1,500 to 50,000. A specific polyurethane segment and a vinyl polymer segment which are obtained by polymerizing 98 to 5 parts by weight of at least one polymerizable unsaturated monomer in the presence of ˜95 parts by weight. The present invention aims to provide a novel and useful magnetic coating material containing a block copolymer having the same.

Here, the so-called high molecular weight azo initiator having a number average molecular weight of 1,500 to 50,000 and having both a urethane bond and a diazo bond in one molecule described above is, for example, the general one described above. Each of the compounds represented by the formulas [I] and [II] has a specific structural unit, and the polyurethane-type polymer polyazo initiator is, for example, azobiscyanopropanol, azobiscyano-n-butanol, azobisisobutanol. Or an azobisalkanol compound such as azobiscyanopentanol; or "VA-080, V
A-082 or VA-086 "(product of Wako Pure Chemical Industries, Ltd.), such as various azoamide polyols, so-called a combination of at least one diazo bond and at least two hydroxyl groups in one molecule. It is in the form obtained by reacting the compound having the polyisocyanate compound with the polyol compound.

That is, such a polyurethane-type polymer polyazo initiator is, for example, isophorone diisocyanate, methylcyclo-hexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate, 4,4'-methylenebis (cyclohexylisocyanate). Various diisocyanates such as 1,3-di (isocyanatomethyl) cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylcyclohexane diisocyanate, tolylene diisocyanate or xylene diisocyanate, or each of these diisocyanates and glycerin, trimethylol Various types such as ethane, trimethylolpropane, pentaerythritol or dipentaerythritol Having a polyhydric alcohol or a functional group capable of reacting with an isocyanate group, for example, 5
Various polyisocyanate compounds such as an adduct with a polyester compound having a number average molecular weight of about 00 to 1,500 and an extremely low molecular weight;

Ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol,
1,4-butanediol, 1,3-butanediol,
1,6-hexanediol, 3-methyl-1,5-pentadiol, neopentyl glycol, cyclohexanedimethanol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3 -Propanediol, 2-ethyl-1,3-hexanediol, 2,
2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate, 12-hydroxystearyl alcohol or polyethylene glycol, polypropylene glycol or polyhexamethylene glycol, or trimethylolethane,
Various di-type compounds such as trimethylolpropane, glycerin, pentaerythritol or hydrogenated bisphenol A.
Or polyols, and further bisphenol A or polyester polyols;

As described above, it can be obtained by addition condensation reaction of a ternary component with various compounds having at least one diazo bond and at least two hydroxyl groups in one molecule. is there.

The number average molecular weight of the above di- or polyol compound is not particularly limited,
From the viewpoint of reactivity and the like, it is preferably up to 1,500, more preferably up to 1,000.

Further, only by exemplifying the typical polyester polyols mentioned above,
Various di- or polyol compounds as described above, isophthalic acid, terephthalic acid, (anhydrous) phthalic acid,
Such as (anhydrous) tetrahydrophthalic acid, (anhydrous) hexahydrophthalic acid, trimellitic anhydride, pyromellitic acid, fumaric acid, maleic acid, succinic acid or azopic acid,
Hydroxyl group-containing polyester resins (including oil-modified types) obtained by dehydration condensation with various di- or polycarboxylic acids (anhydrides) and / or various various kinds such as ε-caprolactone or valerolactone. And a hydroxyl group-containing polyester resin obtained by ring-opening polymerization of the lactone compound, and any of them can be obtained by a known and commonly used reaction method.

In particular, in order to improve the dispersibility of the magnetic recording medium, various carboxyl group-containing diols such as dimethylolpropionic acid and their quaternary ammonium salts; or 2-sulfonic acid-1,4-butane. Diol, 1-sulfonic acid-1,4-butanediol, 3-sulfonic acid-2,5-dimethyl-3-hexene-2,5-
Diol, 3,4-2,5-disulfonic acid-hexanediol, such as 3-sulfonic acid-1,5-pentanediol, and various -SO ₃ H group-containing diols and quaternary ammonium salts thereof are used Is

When a diol containing a carboxyl group and a sulfonic acid group is used, a diol containing an alkali metal sulfonate group and an alkali metal carboxylate group can be obtained by reacting with a quaternary ammonium hydroxide. If you use
When a sulfonic acid amine base and / or a carboxylic acid amine base-containing diol is used by reacting with a primary ammonium halide,
Quaternary ammonium chloride is obtained by reacting with quaternary ammonium hydroxide, etc., but the method is not particularly limited, and the process for synthesizing a high molecular weight azo initiator and a block copolymer or After synthesis, these reactions take place.

Here, as a method for synthesizing the polymer azo initiator, a method in which the above three components are simultaneously charged and reacted, or an isocyanate group-containing polyurethane intermediate, that is, a so-called urethane prepolymer is first prepared. Then, there is a method of reacting this with a compound having at least one diazo bond and at least two hydroxyl groups in one molecule, but such a synthetic method is not particularly limited. Instead, it may be appropriately selected and used.

During the reaction of these di- or polyol compounds with the di- or polyisocyanate compounds, ethylenediamine, hexamethylenediamine, triethylenetetramine, tetraethylenepentamine, bisamino are used as chain extenders. Of course, various polyamine compounds such as propylamine or 4-aminomethyl-1,8-diaminooctane may be used.

Further, only specific examples of the above-mentioned polymerizable unsaturated monomers are exemplified, and various kinds such as styrene, α-methylstyrene, pt-butylstyrene or vinyltoluene are listed. Aromatic vinyl monomers of: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth ) Acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, dibromopropyl (meth) acrylate, tribromophenyl (meth) Acrylate or alkoxy Such Le (meth) acrylate, various (meth) acrylates;

Diesters of various unsaturated dicarboxylic acids such as maleic acid, fumaric acid or itaconic acid with monohydric alcohols; vinyl acetate, vinyl benzoate or "Veova" (vinyl ester manufactured by Shell in the Netherlands)
Various vinyl esters such as: "Biscoat 8F,
8FM, 17FM, 3F or 3FM "(fluorine-containing acrylic monomer manufactured by Osaka Organic Chemical Co., Ltd.), perfluorocyclohexyl (meth) acrylate, di-perfluorocyclohexyl fumarate or N-i-propyl perfluorooctane sulfonamide. Ethyl (meta)
Various (per) fluoroalkyl group-containing -vinyl esters, -vinyl ethers, such as acrylates,-
Various fluorine-containing polymerizable compounds such as (meth) acrylates or unsaturated polycarboxylic acid esters;

Alternatively, various functional group-free vinyl monomers such as olefins such as (meth) acrylonitrile, vinyl chloride, vinylidene chloride, vinyl fluoride or vinylidene fluoride; (meth) acrylamide, dimethyl ( Various amide bond-containing vinyls such as (meth) acrylamide, Nt-butyl (meth) acrylamide, N-octyl (meth) acrylamide, diacetone acrylamide, dimethylaminopropyl acrylamide or alkoxylated N-methylolated (meth) acrylamides. System monomers;

Dialkyl [(meth) acryloyloxyalkyl] phosphates, (meth) acryloyloxyalkyl acid phosphates, dialkyl [(meth)
Acryloyloxyalkyl] phosphite, or (meth) acryloyloxyalkyl acid phosphite, and further, an alkylene oxide adduct of the above (meth) acryloyloxyalkyl acid phosphate or acid phosphite, glycidyl Ester compounds of various epoxy group-containing vinyl monomers such as (meth) acrylate and methylglycidyl (meth) acrylate with phosphoric acid or phosphorous acid or their acidic esters, and further 3-chloro-2
-Various phosphorus atom-containing vinyl monomers such as acid phosphoxypropyl (meth) acrylate;

Various dialkylaminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate,
2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth)
Acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, di-2-hydroxyethyl fumarate, mono-2-hydroxyethyl monobutyl fumarate or polypropylene glycol, or polyethylene glycol mono (meth) acrylate, “Plaxel FM or FA monomer ”(caprolactone addition monomer manufactured by Daicel Chemical Industries, Ltd.)
Various hydroxyalkyl esters of β-ethylenically unsaturated carboxylic acids, or adducts thereof with ε-caprolactone;

Various unsaturated mono- or dicarboxylic acids such as (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid or citraconic acid, and monoesters of these dicarboxylic acids with monohydric alcohols. Various α, β-ethylenically unsaturated carboxylic acids, or the above α, β-ethylenically unsaturated carboxylic acid hydroxyalkyl esters, and maleic acid, succinic acid, phthalic acid, and hexahydrophthalic acid. , Tetrahydrophthalic acid, benzenetricarboxylic acid, benzenetetracarboxylic acid, "Himimic acid" (product of Hitachi Chemical Co., Ltd.), adduct of various polycarboxylic acids such as tetrachlorophthalic acid or dodecynylsuccinic acid Such as various unsaturated carboxylic acids and "CARDURA E" (made by Shell Co. Glycidyl esters of branched synthetic resin fatty acids), such as coconut oil fatty acid glycidyl ester or octylic acid glycidyl ester, various 1
Of monohydric carboxylic acid monoglycidyl esters or butylglycidyl ethers, adducts with various monoepoxy compounds such as ethylene oxide or propylene oxide, or adducts thereof with ε-caprolactone; various types such as hydroxyvinyl ether Hydroxyl group-containing monomers of

2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3
-Hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, di- 2-hydroxyethyl fumarate, mono-2-hydroxyethyl-monobutyl fumarate or polyethylene glycol mono (meth)
Various α, β-unsaturated carboxylic acid hydroalkyl esters such as acrylate, and maleic acid, succinic acid,
Additives of various polycarboxylic acid anhydrides such as phthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid, benzenetricarboxylic acid, benzenetetracarboxylic acid, "hymic acid", tetrachlorophthalic acid or dodecynylsuccinic acid Various carboxyl group-containing monomers such as;

Vinylethoxysilane, α-methacryloxypropyltrimethoxysilane, trimethylsiloxyethyl (meth) acrylate and the like, and further "KR-215 or X-22-5002".
Examples include various silicon-based monomers such as [Product of Shin-Etsu Chemical Co., Ltd.].

Here, in order to improve the dispersibility of the magnetic recording medium, a quaternary ammonium salt of the above-mentioned monomers having a carboxyl group, parastyrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid or sulfonic acid. Various --COOH groups and / or --S, such as quaternary ammonium salts of ethyl (meth) acrylates.
O ₃ H group-containing monomers and their quaternary ammonium salts are used, and when carboxyl group- and sulfonic acid group-containing monomers are used, by reacting with quaternary ammonium hydroxide, When using alkali metal sulfonate group- and alkali metal carboxylate group-containing monomers,
By reacting with a quaternary ammonium halide, further, when the amine base-containing monomer of sulfonic acid and / or amine base of carboxylic acid is used,
A quaternary ammonium chloride is obtained by reacting with a quaternary ammonium hydroxide, but such a method is not particularly limited, and, in the synthesis process of the block copolymer and / or after the synthesis,
The quaternary ammonium chloride reaction is carried out.

[0037] However, said -COOH groups and / or -SO ₃ H group-containing diols and or their quaternary ammonium salts, -COOH group and / or -SO ₃ H
The use of the group-containing monomers and their quaternary ammonium salts may be carried out at least during the synthesis of the high molecular weight azo initiator or the synthesis of the block copolymer, respectively. It is good if used.

Thus, the polymerization for obtaining the vinyl-based (co) polymer can be carried out by using the above-mentioned respective raw material components by making full use of a known and common copolymerization reaction method. Bisisobutyronitrile (AIBN), benzoyl peroxide (BPO), t-butyl perbenzoate (TBPB), t-butyl hydroperoxide, di-t-butyl peroxide (DTBPO) or cumene hydroperoxide (CHP). Needless to say, various radical-generating polymerization catalysts such as those mentioned above may be used alone or in combination of two or more kinds.

The magnetic coating material of the present invention can be obtained by using the block copolymer thus obtained, the magnetic powder and the coating solvent as essential components.
It goes without saying that a curing agent, a dispersant, a lubricant, an abrasive or an antistatic agent may be mixed.

Here, only representative examples of the above-mentioned magnetic powders will be exemplified. Γ-ferrite, cobalt γ-ferrite, barium-ferrite, metallic iron and their alloys (so-called metal powder). However, if only representative ones are exemplified as the coating solvent, various ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone; methanol, ethanol, propanol or butanol, Various alcohols; various esters such as ethyl acetate, butyl acetate or ethylene glycol monoacetate;

Various ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or dioxane; various aromatic hydrocarbon solvents such as benzene, toluene or xylene; various halogenations such as methylene chloride, carbon tetrachloride or chloroform Hydrocarbons; or various aprotic polar solvents such as dimethylformamide, dimethylformamide sulfoxide, sulfolane or N-methylpyrrolidone, but of course, even the solvent used when synthesizing the block copolymer Good.

The curing agent used if necessary is
Although not particularly limited, a low molecular weight polyisocyanate is suitable, and specifically, "Bernock D-7" is used.
50 "or" Chris Bonn NX "[These are all products of Dainippon Ink and Chemicals, Inc.]," Desmodur
L "[Sumitomo Bayer Co., Ltd. product]," Coronate L "
[Product of Nippon Polyurethane Co., Ltd.], “Takenate D-
102 "[Takeda Pharmaceutical Co., Ltd. product]," Barnock
DN-950 "[product of Dainippon Ink and Chemicals, Inc.],
"Desmodur R" or "Desmodur R"
Various polyisocyanate resins such as F ”(the above are products of Sumitomo Bayer Co., Ltd.) or the above-mentioned diisocyanate compounds are particularly representatively used.

The ratio of the block copolymer to the low molecular weight polyisocyanate is not particularly limited, but preferably, the various types as listed above are used with respect to 100 parts by weight of the block copolymer. By adding the low molecular weight polyisocyanates of 3 to 40 parts by weight and curing, the mechanical strength, abrasion resistance, wet heat resistance, solvent resistance and base material of the urethane resin after curing are The adhesion, etc. of can be greatly improved.

Further, only representative examples of the above-mentioned dispersants include caprylic acid, capric acid, lauric acid, myristic acid, stearic acid, oleic acid, elaidic acid, linoleic acid or linolenic acid. As described above, various fatty acids having 12 to 18 carbon atoms; or metal soaps composed of alkali metals or alkaline earth metals of such fatty acids; or lecithin.

Further, silicone oil, carbon black, graphite or the like is given as a representative of the above lubricants. Furthermore, as the above-mentioned abrasive, any one generally used may be used, and specifically, fused alumina, silicon carbide chromium oxide, diamond, artificial diamond, garnet, etc. are particularly representative. As.

As the above-mentioned antistatic agents, only representative ones are exemplified, and various conductive powders such as graphite or carbon black; various natural surfactants such as saponin; Various nonionic surfactants such as alkylene oxide type, glycerin type or glycidol type; various cationic surfactants such as higher alkylamines, quaternary ammonium salts or sulfonium compounds; carboxylic acids, sulfonic acids, Various anionic surfactants containing an acidic group such as phosphoric acid, sulfuric acid ester group or phosphoric acid ester group; or various amphoteric surfactants such as sulfuric acid or phosphoric acid ester of amino acids, aminosulfonic acids or aminoalcohols And so on.

For the above block copolymer,
A thermoplastic urethane resin, which is usually used,
Vinyl chloride vinyl acetate copolymer, fibrin resin, vinyl chloride polymer, polyvinyl butyral resin, thermoplastic polyester resin, vinyl chloride propionate vinyl copolymer, epoxy resin or phenoxy resin, etc. It is also possible to use in combination.

The block copolymer obtained as described above, which is used in the present invention, is particularly excellent in various properties such as pigment dispersibility, wet heat resistance, abrasion resistance, fluidity and permanent elongation. Therefore, it can be used for applications other than the binder of the magnetic recording medium.

That is, for example, various printing inks,
Magnetic rubber, various paints, conductive resins, adhesives and the like are mentioned as the most important ones.

[0050]

EXAMPLES Next, the present invention will be described more specifically with reference to Reference Examples, Examples and Comparative Examples. In the following, all parts and percentages are based on weight unless otherwise specified. .

Reference Example 1 (Preparation Example of Polymer Azo Initiator) In a four-necked flask equipped with a thermometer, a stirrer and a reflux condenser, 1,500 parts of methyl ethyl ketone, 58 parts of azobiscyanopropanol and di- 0.2 part of n-butyltin dilaurate was charged, and while stirring and cooling with ice, 546 parts of hexamethylene diisocyanate was added to 2 parts.
After dropping over a period of time, the temperature was raised to 20 ° C., the temperature was maintained for 2 hours to continue the reaction, and then ice cooling was performed again.

Then, dipropylene glycol 396
Then, the temperature was raised to 30 ° C., and the temperature was maintained for 10 hours to continue the reaction. The polyurethane polymer azo initiator obtained here is a gel permeation
The number average molecular weight in terms of polystyrene measured by chromatography (GPC) is 20,500 at 25 ° C.
Has a Gardner viscosity of Z ₁ and a nonvolatile content of 4
It was 0%.

To determine other property values for this polymeric azo initiator, 5 parts hydroquinone and 20 parts n-butanol were added to 20 parts of the initiator at 100 ° C. Continue heating over time,
The initiator was allowed to decompose.

The number average molecular weight of the decomposed product obtained here was 3,200, and it was found that the objective polymer azo initiator had an average of 6.4 diazo bonds in one molecule.

Reference Example 2 (same as above) In a container similar to Reference Example 1, 1,0 of methyl ethyl ketone was added.
After charging 00 parts, 500 parts of n-methylpyrrolidone, 366 parts of dipropylene glycol, 0.1 part of dimethylolpropionic acid and di-n-butyltin dilaurate, after heating to 80 ° C. under stirring, 546 parts of hexamethylene diisocyanate was added dropwise over 2 hours, and the reaction was continued at the same temperature for 5 hours.

The polystyrene equivalent number average molecular weight of the obtained isocyanate group-containing polyurethane measured by (GPC) was 3,700. However, after being subjected to a treatment of reacting an isocyanate group with diethylamine, it is provided for measurement by GPC.

Then, 2,442 parts of this isocyanate group-containing polyurethane was charged into a reaction vessel similar to that described above, and 58 parts of azobisisopropanol was added to the polyurethane under ice-cooling. 30 ° C
The temperature was raised to 10 ° C. and the reaction was carried out at the same temperature for 10 hours.

The number average molecular weights of the thus obtained polyurethane polymer azo initiator and the decomposed product were 1 and 2, respectively.
It is known to be a polyurethane polymeric azo initiator having an average of 6.0 diazo bonds in one molecule.

The target initiator solution had a nonvolatile content of 4
0% and the Gardner viscosity at 25 ° C. is Y
-Z. Reference Example 3 (same as above) A reaction vessel equipped with a thermometer, a stirrer and an air condenser was charged with 614 parts of adipic acid, 438 parts of neopentyl glycol and 698 parts of isophthalic acid and allowed to react at 140 ° C. for 1 hour. Then, the temperature is gradually raised to 220 ° C. over 2 hours, and the reaction is carried out at the same temperature for 6 hours to obtain a polyester having an acid value of 2, a hydroxyl value of 78, and a number average molecular weight of 1,400. A resin was obtained.

Next, in the same reaction vessel as in Reference Example 1, 797 parts of the above polyester resin, 55 parts of azobiscyanopropanol, and 0. 0% of di-n-butyltin dilaurate were added.
After charging 2 parts and 1,500 parts of methyl ethyl ketone, 14 parts of tolylene diisocyanate was added under ice cooling.
8 parts was added dropwise over 2 hours.

After the dropping, the temperature was raised to 30 ° C. and the temperature was kept for 10 hours to continue the reaction. As a result, the number average molecular weight was 22,000, the viscosity was WX, and ,
A solution of the desired polyurethane polymer azo initiator having a nonvolatile content of 40% was obtained.

To 20 parts of this polyurethane polymer azo initiator, 5 parts of hydroquinone and 20 parts of n-butanol were added, and heating was continued at 100 ° C. for 10 hours to give the polymer azo initiator. When the initiator was decomposed, the number average molecular weight of this decomposed product was 3,30.
It was thus found that the polyurethane polymeric azo initiator had an average of 6.7 diazo bonds in one molecule.

Reference Examples 4 to 5 (same as above) Under the conditions shown in Table 1, the solvent, azoalkanol compound, polyol compound and polyisocyanate compound as shown in Table 1 were used. Various target polyurethane polymer azo initiators were obtained in the same manner as in Reference Example 1 except that the reaction was performed.

The values of various properties of each polymer azo initiator are as shown in the same table.

[0065]

[Table 1]

[0066]

[Table 2]

Reference Example 6 A four-necked flask equipped with a thermometer, a stirrer and a reflux condenser was charged with 150 parts of toluene and 5 parts of dimethylformamide.
Charge 0 part and 500 parts of methyl ethyl ketone,
The temperature was raised to 0 ° C. and 550 of methyl methacrylate was added.
Parts, 180 parts of t-butyl methacrylate, 50 parts of 2-hydroxyethyl methacrylate, 2-acrylamido-
A mixed solution of 500 parts of 2-methylpropanesulfonic acid and the polyurethane polymer azo initiator obtained in Reference Example 1 was added dropwise over 4 hours, and after the completion of the addition, the same temperature was maintained for 10 hours. It was held and the polymerization reaction was continued.

Next, 10.6 parts of tetramethylammonium hydroxide was reacted to convert the sulfonic acid group into a quaternary ammonium salt, and the precipitated salt was removed by filtration to give a number average molecular weight of 23,300. Polyurethane-acrylic resin block copolymer with a non-volatile content of 50%
A solution having a Gardner viscosity of YZ at 25 ° C was obtained.

[0069]

[Table 3]

Reference Examples 7 to 12 Polymerization solvents, initiators and polymerizable unsaturated monomers as shown in Table 2 were used, and the polymerization conditions were as shown in the same table. Various block copolymers were obtained in the same manner as in Reference Example 6 except that the above was changed to.

[0071]

[Table 4]

[0072]

[Table 5]

[0073]

[Table 6]

[0074]

[Table 7]

Reference Example 13 A reaction vessel equipped with a thermometer, a stirrer and an air condenser was charged with 1,218 parts of adipic acid and 720 of 1,4-butylene glycol and allowed to react at 140 ° C. for 1 hour. It took 2 hours and gradually increased to 220
The temperature is raised to ℃ and reacted at the same temperature for 6 hours.
A polyester resin having a hydroxyl value of 59 was obtained.

Then, 921 parts of the polyester resin thus obtained, 6000 parts of methyl ethyl ketone,
400 parts of dimethylformamide and 79 parts of tolylene diisocyanate were charged, and the reaction was continued at 80 ° C. for 10 hours.

The number average molecular weight of the polyurethane resin thus obtained was 30,000. Reference Example 14 The same reaction vessel as in Reference Example 13 was charged with 522 adipic acid.
Part, 498 parts of isophthalic acid, 664 of terephthalic acid
Part, 186 parts of ethylene glycol, 416 parts of neopentyl glycol and 360 of 1,4-butylene glycol were charged and allowed to react at 140 ° C. for 1 hour, and then gradually heated to 220 ° C. over 2 hours. Then, the reaction was carried out at the same temperature for 6 hours to obtain a polyester resin having an acid value of 3 and a hydroxyl value of 45.

Then, 93% of this polyester resin was used.
9 parts, 600 parts of methyl ethyl ketone, 400 parts of dimethylformamide and 61 parts of tolylene diisocyanate were charged, and the reaction was continued at 80 ° C. for 10 hours.

The number average molecular weight of the polyurethane resin thus obtained was 31,500.

Example 1 100 parts of the block copolymer obtained in Reference Example 6, 738 parts of methyl ethyl ketone, and 2 parts of Fe--Ni alloy magnetic powder.
A mixture of 50 parts, 8.6 parts of carbon black and 3.5 parts of a lubricant was kneaded in a ball mill for 48 hours, and then "Bernock D-750" [manufactured by Dainippon Ink and Chemicals, Inc., Low molecular weight polyisocyanate]
Add 3 parts, further knead for 1 hour, coat on a polyethylene terephthalate substrate film having a thickness of 10 microns so that the thickness after drying will be 8 microns, dry and calender. A magnetic recording tape was produced by cutting it into a predetermined width.

Next, the obtained magnetic tape was subjected to the following tests to evaluate and evaluate various performances. The results are collectively shown in Table 3.

<< Magnetic Tape Gloss Test >> The magnetic surface of each magnetic tape before calendering was measured with a digital gonio-gloss meter at an incident angle of 45 degrees and a reflection angle of 45 degrees.

<< Moisture and Heat Resistance Durability Test of Magnetic Tape >> Each of the obtained magnetic tapes was tested at 70 ° C. and a relative humidity of 95%.
The sample was stored under the following conditions for 2 weeks, left at room temperature for 24 hours, and then subjected to a running test with a video tape recorder for evaluation and evaluation. ○ ……… No problem in repeated running △ ……… Slightly uneven running × ………… Stuck due to severe tape adhesion

<< Abrasion Resistance Test of Magnetic Tape >> The magnetic surface of the obtained magnetic tape was measured using a Taber abrasion tester.
The number of times until the magnetic layer came off was measured.

<< Surface Smoothness Test of Magnetic Tape >> It was visually determined.

Examples 2 to 7 and Comparative Examples 1 and 2 Under the compounding conditions shown in Table 3, a magnetic tape was prepared in the same manner as in Example 1 and evaluated. The results are shown together in the same table.

[0087]

[Table 8]

<< Footnotes in Table 3 >>"VAGH" --- Vinyl chloride-vinyl acetate copolymer "Bernock D-750" manufactured by Union Carbide Co. of the United States ... manufactured by Dainippon Ink and Chemicals, Inc. Polyisocyanate resin

[0089]

[Table 9]

[0090]

[Table 10]

[0091]

As shown in Table 3, the present invention makes it possible to obtain good magnetic recording medium dispersibility and surface smoothness, durability and durability of the magnetic recording medium by using the block copolymer thus obtained. It provides a magnetic paint having extremely high wear resistance and extremely high practicality.

Claims (9)

[Claims] 1. A group which has both a polyurethane segment and a vinyl polymer segment and is a group of --SO ₃ X group and / or --COOX group (where X represents a quaternary ammonium group). A magnetic coating material comprising a block copolymer also possessed by the above and a magnetic powder as essential components. 2. A group which has both a polyurethane segment and a vinyl polymer segment and is a group of --SO ₃ X group and / or --COOX group (where X represents a quaternary ammonium group). A magnetic coating material containing, as essential components, a block copolymer also possessed by the above, magnetic powder, and polyisocyanate. 3. A combination of the above-mentioned polyurethane segment and vinyl polymer segment, and —SO ₃ X
Group and / or a -COOX group (where X represents a quaternary ammonium group) also has a block copolymer, a block copolymer having a sulfonic acid group and / or a carboxyl group, It is obtained by reacting with quaternary ammonium hydroxide,
The magnetic coating material according to claim 1. 4. A combination of the above-mentioned polyurethane segment and vinyl polymer segment, and —SO ₃ X
Group and / or a -COOX group (provided that X represents a quaternary ammonium group), a block copolymer having an alkali metal sulfonate group and / or
The magnetic coating material according to claim 1 or 2, which is obtained by reacting a block copolymer having an alkali metal carboxylate group with a quaternary ammonium halide. 5. A combination of the above-mentioned polyurethane segment and vinyl polymer segment, and —SO ₃ X
A block copolymer having a group and / or a —COOX group (wherein X represents a quaternary ammonium group) has a sulfonic acid amine base and / or a carboxylic acid amine base. The magnetic coating material according to claim 1 or 2, which is obtained by reacting a copolymer with a quaternary ammonium hydroxide. 6. A combination of the above-mentioned polyurethane segment and vinyl polymer segment, and —SO ₃ X
A block copolymer having a group and / or a group of —COOX group (where X represents a quaternary ammonium group) has at least one compound represented by the general formula: (Wherein R ₁ is an alkylene group, a cyclic alkylene group, an alkylene group having an ester group, a benzene ring, or an alkylene group containing a benzene ring, and R ₂ and R ₂ 'are the same. May be different, alkylene group, alkylene group containing a cyano group,
It represents an alkylene group containing an amide bond or an alkylene group having both an amide bond and a hydroxyl group. ) And the general formula: (Provided that R ₃ in the formula represents a polyol residue.) Is obtained by polymerizing at least one polymerizable unsaturated monomer in the presence of a compound having a structural unit represented by The magnetic paint according to claim 1 or 2, which is used. 7. A combination of the above-mentioned polyurethane segment and vinyl polymer segment, and —SO ₃ X
A block copolymer having a group and / or a group of —COOX group (where X represents a quaternary ammonium group) has at least one compound represented by the general formula: (Wherein R ₁ is an alkylene group, a cyclic alkylene group, an alkylene group having an ester group, a benzene ring, or an alkylene group containing a benzene ring, and R ₂ and R ₂ 'are the same. , Which may be different, represent an alkylene group, an alkylene group containing a cyano group, an alkylene group containing an amide bond, or an alkylene group having both an amide bond and a hydroxyl group. Formula (Provided that R ₃ in the formula represents a polyol residue) and has a structural unit of 1,500
~ 2 of compounds having a number average molecular weight of 50,000
The magnetic paint according to claim 1 or 2, which is obtained by polymerizing 98 to 5 parts by weight of at least one polymerizable unsaturated monomer in the presence of 95 parts by weight. 8. At least one molecule in said one molecule,
General formula: (In the formula, R ₁ is an alkylene group, a cyclic alkylene group, an alkylene group having an ester group, a benzene ring, or an alkylene group containing a benzene ring, and R ₂ and R ₂ 'are the same. , Which may be different, represent an alkylene group, an alkylene group containing a cyano group, an alkylene group containing an amide bond, or an alkylene group having both an amide bond and a hydroxyl group. Formula (However, R ₃ in the formula represents a polyol residue.), A compound having a structural unit represented by —SO
₃ X groups and / or -COOX group (wherein, X is. To represent a quaternary ammonium group) are those having a magnetic paint according to claim 6 or 7. 9. The polymerizable unsaturated monomer is --S
O ₃ X group and / or —COOX group (where X is 4
It represents a primary ammonium group. 7. The polymerizable unsaturated monomer having) is an essential component.
Or the magnetic paint according to 7.