JPH10255253A - Magnetic storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetic storage medium which assures excellent dispersion property of fine magnetic particles of BET-40m<2> /g or more or magnetic particle such as metal magnetic powder, barium-ferrite, etc., obtains gloss of magnetic film and higher rectangular ratio and shows excellent durability. SOLUTION: In a magnetic storage medium where the nonmagnetic carrier is coated with a magnetic paint containing ferromagnetic power into a binder including polyester amide resin containing ester coupling and amide coupling, polyester amide resin in the binder contains sulfonic acid metal chloride coupled with the aromatic group of dicalbonic acid element of 4 to 400 equivalent/10<6> g per polymer and amide coupling of 100 to 3,000equivalent/10<6> g per polymer and mean amount of molecules is 8,000 to 60,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic tape and a magnetic disk. More specifically, the present invention relates to a magnetic recording medium using a polyesteramide resin having excellent properties as a binder component of a magnetic layer provided on a nonmagnetic support.

[0002]

2. Description of the Related Art A magnetic tape as a general-purpose magnetic recording medium is prepared by dispersing needle-like magnetic particles having a major axis of 1 μm or less together with a suitable additive (dispersant, lubricant, antistatic agent, etc.) in a binder solution. It is made by making a magnetic paint and applying it to a polyethylene terephthalate film.

[0003] The characteristics required for the binder of the magnetic recording medium include the dispersibility, filling property, orientation, magnetic layer durability, abrasion resistance, heat resistance, smoothness, and non-magnetic support of the magnetic particles. The binder plays a very important role, for example, in terms of adhesiveness. Conventionally used binders include vinyl chloride / vinyl acetate copolymer, vinyl chloride / vinyl acetate / vinyl alcohol copolymer, vinyl chloride / vinylidene chloride copolymer, polyurethane resin, polyester resin,
Fuclonitrile-butadiene copolymer, tonylcellulose, cellulose butyrate, epoxy resin, acrylic resin and the like are used.

[0004]

Among these resins, polyurethane resins have excellent properties such as toughness and abrasion resistance as compared with other resins due to intermolecular hydrogen bonds due to urethane bonds, but are not always satisfactory. Not something.

The conventional adipate type or caprolactone type polyurethane resin alone is inferior in properties such as blocking resistance, heat resistance and running stability. For this reason, a mixed system of a polyurethane resin and nitrocellulose or a vinyl chloride / vinyl acetate copolymer is particularly used. However, characteristics such as durability, abrasion resistance, and running stability are still insufficient in fields requiring high performance such as video tapes, tapes for computer computers, and floppy disks.

[0006] In particular, the recent high quality of magnetic tapes has been remarkable, and the fineness of magnetic powder and the smoothness of magnetic coating have been progressing, and accordingly, the binder resin has higher dispersibility and higher durability. Sex is required. Further, metal magnetic powder and barium ferrite magnetic powder have become popular due to the increase in recording density, and a binder resin having higher performance is strongly demanded.

Conventionally, a method for improving the dispersibility of magnetic particles
For example, JP-B-57-3134, JP-B-5-5
As disclosed in JP-A-8-41564 and the like,
Polyester resin containing sulfonic acid metal base,
Or use polyurethane resin as binder resin
That is stated. Certainly, more general use
BET30m which has been used as magnetic particles^TwoF / g or less
e_TwoO_Three, Co-FeO_ThreeFor magnetic particles such as
Polyester resin or polyurethane resin
Shows excellent dispersibility, but finer BET 40m^Two/ G
The above Fe_TwoO _Three, Co-Fe_TwoO_ThreeOr metal,
Barium-ferrite and other magnetic materials for high recording density magnetic recording materials
Higher dispersibility is required for the conductive particles.

Further, as described above, the smoothing of the magnetic recording material progresses, and the magnetic recording material is required to have higher running durability. In order to meet the demands of the market, the present invention has been studied to maintain the dispersibility of polyurethane resin and to improve abrasion resistance and durability.However, it is difficult to achieve both durability and magnetic properties. The response has been required.

As a method for improving the durability performance, means such as increasing the urethane group concentration in order to increase the hydrogen bond concentration or increasing the crosslink density by providing a branched structure have been proposed and studied. In any case, the durability performance tends to be improved, but there is a problem that the optical surface gloss or squareness ratio of the coating film, which is a measure of dispersibility, is lowered particularly in the case of metal magnetic powder.

[0010]

Means for Solving the Problems The inventors of the present invention have proposed the use of metal magnetic powder in magnetic particles for high recording density magnetic recording materials and the like.
As a result of intensive studies to obtain a resin having excellent dispersibility and running durability, a binder resin having excellent surface gloss and squareness ratio and excellent durability was found, and the present invention was achieved.

That is, the present invention relates to a magnetic recording medium in which a magnetic coating material containing a ferromagnetic powder in a binder containing a polyesteramide resin containing an ester bond and an amide bond is applied to a nonmagnetic support. The polyester amide resin contained therein a metal salt of sulfonic acid bonded to an aromatic dicarboxylic acid component in an amount of 4 to 400 equivalents / 10 ⁶ g per polymer, and an amide bond in an amount of 100 to 3 equivalents per polymer.
000 equivalents / 10 ⁶ g and a number average molecular weight of 8,
000 to 60,000.

The polyesteramide resin of the present invention can be obtained by a known production method. That is, one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids or aliphatic dicarboxylic acids, and one or more aromatic diamines, alicyclic diamines, aliphatic diamines, aminocarboxylic acids or lactams, and fats having a molecular weight of 400 or less It can be obtained by polymerizing an alkylene oxide adduct of an aromatic glycol, an alicyclic glycol or an aromatic diol by a known method.

The polyesteramide resin of the present invention is characterized in that the resin contains 4 to 400 equivalents / 10 ⁶ g of a metal sulfonate group bonded to an aromatic dicarboxylic acid component. A known technique can be applied as it is. For example, use of a dicarboxylic acid containing a sulfonic acid metal base in an aromatic state during polymerization of a polyesteramide can be mentioned.

Among the dicarboxylic acid components, compounds containing a sulfonate group include 5-sodium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid, 2-sodium sulfoisophthalic acid, 2-lithium sulfoisophthalic acid, and 2-potassium sulfoisophthalic acid. And terephthalic acid. On the other hand, dicarboxylic acids containing no sulfonic acid metal base include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid (anhydride), 2,6-naphthalenedicarboxylic acid, and 1,5-naphthalenedicarboxylic acid; 4-cyclohexanedicarboxylic acid, 1,3
-Cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, aliphatic dicarboxylic acids such as dodecandioic acid, and the like. In addition, hydroxycarboxylic acids such as p- (hydroxyethoxy) benzoic acid and the like, and lactones such as caprolactone and valerolactone can also be used as long as the properties are not impaired. The content of the sulfonic acid metal base-containing dicarboxylic acid in all dicarboxylic acid components in the polyesteramide resin is 0.5 to 8 mol%.
And desirably 2 to 5 mol%.

The amino compound used for producing the polyesteramide resin of the present invention includes ethylenediamine,
Aliphatic diamines such as propylenediamine, butylenediamine, hexamethylenediamine, 2,2,4-trimethyl-1,6-hexamethylenediamine, neopentylenediamine, piperazine, 1,4-diaminopiperazine;
Alicyclic diamines such as 1,3-bis (aminomethyl) cyclohexane, dicyclohexylmethanediamine and isophoronediamine; aromatic diamines such as diphenylmethanediamine, phenylenediamine and tolylenediamine;
Aromatic ring-containing aliphatic diamines such as xylylenediamine can also be used.

Further, 11-aminoundecanoic acid, 12-
Amino acids such as aminodotecanic acid or lactams such as caprolactam can also be used.

The glycol having a molecular weight of 400 or less used in the production of the polyesteramide resin of the present invention includes ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, , 6-hexanediol, neopentyl glycol, 3-methylpentanediol, 1,9-
Aliphatic glycols such as nonanediol, alicyclic glycols such as 1,4-cyclohexanedimethanol, ethylene oxide adducts of bisphenol A, and alkylene oxide adducts of aromatic diols such as ethylene oxide adducts of hydroquinone. Can be.

The polyesteramide resin of the present invention can be produced by a method in which a dicarboxylic acid component, an amino compound, and a glycol component are simultaneously charged in a reaction vessel, and after a dehydration reaction, polymerized under reduced pressure, or by reacting a dicarboxylic acid and an amino compound first. A method in which a carboxyl group-terminated polyamide oligomer is obtained in advance, a glycol component is added and esterification is performed, and then a polycondensation reaction is performed. Alternatively, an amino compound is added to the carboxyl group-terminated polyester oligomer to perform a polycondensation reaction. Alternatively, a method of performing a polycondensation reaction after obtaining a carboxyl group-terminated polyester oligomer and an amino group-terminated polyamide oligomer in advance, etc., can be appropriately selected.

The polyamide amide resin of the present invention is characterized by containing 100 to 3,000 equivalents / 10 ⁶ g, preferably 600 to 2,000 amide bonds in the molecule. On the other hand, if it exceeds 3,000, the solubility in a solvent becomes poor, and the stability of the magnetic paint becomes extremely poor.

The polyesteramide resin of the present invention has a number average molecular weight of 8,000 to 60,000, preferably 15,000.
0-50,000, but with a number average molecular weight of 8,000
If it is less than 0, excellent abrasion resistance and durability cannot be obtained. Conversely, if it exceeds 60,000, the solution viscosity when dissolved in an organic solvent becomes too high, and the paint stability becomes poor, which makes industrially difficult to carry out. Becomes

In the present invention, in addition to the polyesteramide resin used in the present invention, another resin may be added for the purpose of controlling flexibility, improving cold resistance and heat resistance, and / or adding polyester resin. It is desirable to mix a compound which reacts with the amide resin and crosslinks. Other resins include vinyl chloride resin, polyester resin, cellulose resin, epoxy resin, phenoxy resin, polyvinyl butyral, acrylonitrile-butadiene copolymer, and polyurethane resin.

On the other hand, compounds that crosslink with the polyesteramide resin include polyisocyanate compounds, epoxy resins, melamine resins, urea resins and the like, and among these, polyisocyanate compounds are particularly desirable.

The ferromagnetic particles used in the magnetic layer of the magnetic recording medium of the present invention include γ-Fe2O3, γ-Fe2O3 and Fe3O4.
Crystal, CrO2, γ-Fe2O3 or Fe3 coated with cobalt
O4, metal, barium ferrite and Fe-Co, Fe-Co
And ferromagnetic alloy powders such as -Ni.

In the magnetic recording medium of the present invention, if necessary, a plasticizer such as dibutyl phthalate and triphenyl phosphate, dioctyl sulfo sodium succinate, t
-A lubricant such as butylphenol / polyethylene ether, ethylnaphthalene / sodium sulfonate, dilauryl succinate, zinc stearate, soybean oil lecithin, silicone oil and various antistatic agents can be added.

(Function) The polyesteramide resin of the present invention is characterized in that the resin contains an appropriate amount of a metal sulfonate group and an amide group, and has excellent dispersibility in magnetic particles. A magnetic recording medium having a high squareness ratio can be obtained. Further, the magnetic recording medium using the polyesteramide resin of the present invention has excellent durability, and in the conventional technology, there is a problem that the gloss and the squareness ratio of the coating film decrease with the improvement of the durability. However, the polyesteramide resin of the present invention has made it possible to achieve both magnetic properties and durability.

[0026]

The present invention will be specifically illustrated by the following examples. In the examples, “part” indicates a polymerized part. During implementation, each measurement item was based on the following method.

Magnetic layer gloss: Surface gloss was measured with a gloss meter. The higher the gloss, the better the dispersibility of the magnetic particles.

Abrasion state after running 100 times: Sony 8
The wear state after running 100 times with the mm video deck EV-A300 was visually observed. …: Slight scratches on the magnetic layer △: Slight scratches on the magnetic layer ×: Slight scratches on the magnetic layer

Still characteristic: The time required for the recording to disappear in a still state in a video deck was measured.
(Atmospheric temperature 20 ° C, atmospheric humidity 50% RH)

Preparation Examples A and B of Amide Group-Containing Compounds 71.9 parts of sebacic acid, 28.1 parts of 2,2 ', 4-trimethylhexamethylenediamine, 0.4 part of a 50% aqueous solution of hypophosphorous acid and water After 75 parts were placed in a reaction vessel and purged with nitrogen, the mixture was reacted under pressure at a temperature of 200 ° C. for 1.5 hours. The temperature was raised to 240 ° C. while further distilling off water, and the reaction was continued for 2 hours. Sebacic acid / 2,2 ′, 4
-Trimethylhexamethylenediamine was reacted at a ratio of 1/2 mole to obtain an amide group-containing compound A having a carboxyl group at both terminals. Its acid value is 3800 equivalent / 10
^The amide bond concentration was 6800 g / 10 ⁶ g. Similarly, an amide group-containing compound B obtained by reacting 1,6-hexamethylenediamine and sebacic acid at a molar ratio of 1: 2 was obtained. Its acid value is 4,100 equivalent / 10 ⁶
g, amide bond concentration was 4,100 equivalent / 10 ⁶ g.

Production Example C of Amide Group-Containing Compound C. A solution consisting of ethyl 4-aminobenzoate, 160 parts of pyridine and 200 parts of N-methylpyrrolidone was stirred, and while cooling with water, 204 parts of isophthaloyl chloride and 150 parts of N-methylpyrrolidone. Was added dropwise over 30 minutes. After completion of the dropwise addition, the temperature was raised to 60 ° C., and the reaction was carried out for 1 hour.
Into 00 parts, precipitated and filtered. After washing with water and ethanol, recrystallization was performed with methyl ethyl ketone / acetone = 3/1. The obtained amide group-containing compound C was subjected to elemental analysis,
The following compounds were obtained from MR, and the amide bond concentration was 4, 4
60 equivalents / 10 ⁶ g

[0032]

Embedded image

Synthesis Examples 1-8 of Polyesteramide In a flask equipped with a thermometer, a condenser, and a stirrer, 116 parts of dimethyl terephthalate and 109 parts of dimethyl isophthalate were placed.
Parts, dimethyl 5-sodium sulfoisophthalate 1
1.8 parts, 149 parts of ethylene glycol, 166 parts of neopentyglycol, and 0.07 part of tetrabutyl titanate were charged and transesterification was performed at 160 to 220 ° C for 6 hours. After the atmosphere in the system was replaced with nitrogen, 421 parts of the amide group-containing compound 1 shown in Table 1 were added, and an esterification reaction was carried out at 200 to 22 ° C for 3 hours. Next, the pressure inside the system was gradually reduced, and the excess glycol component was distilled off.
C. and 5 mmHg. And 0.2-0.5mm
A polycondensation reaction was performed at 250 g of Hg for 80 minutes to obtain a polyesteramide resin 1. The obtained resin was analyzed by high performance liquid chromatography to have a number average molecular weight of 23,000 in terms of standard polystyrene. From the elemental analysis, the amount of the metal sulfonate was 54 equivalent / 10 ⁶ g. The same amount of the amide group of the amide group-containing dibasic acid used as the raw material was detected in the polyesteramide from the infrared absorption spectrum and NMR. The resin composition was as described in Table 1. Similarly, using the raw materials described in Table 1, the polyester amide 2 was subjected to a transesterification reaction / polycondensation reaction.
~ 8. Table 1 shows the composition and characteristics of the obtained resin. In Table 1, the solubility was evaluated as ○ when the solid content concentration was 10% and methyl ethyl ketone / toluene / cyclohexanone could be uniformly dissolved in 1/1/1.

Comparative Synthesis Examples of Polyesteramides 1 to 6 Polyesteramides were obtained in the same manner as in Synthesis Example 1 of polyesteramide except that dimethyl 5-sodium sulfoisophthalate was not contained as an acid component. According to the same analysis as in Synthesis Example 1, the polyesteramide obtained in Comparative Synthesis Example 1 contained no sulfonic acid metal salt, had an amide bond concentration of 2,200 equivalents / 10 ⁶ g, and a number average molecular weight of 25.0.
00, the solubility was good. Polyester amides having the compositions shown in Table 2 were obtained in the same manner as in Synthesis Example 1 or 3. The polyesteramide obtained in Comparative Synthesis Example 2 is
The solubility was poor. The polyesteramide obtained in Comparative Synthesis Example 3 had an amide bond concentration of 87 equivalents / 10 ⁶ g. In Comparative Synthesis Examples 4 and 5, the concentration of the metal sulfonic acid salt was 3,450 equivalent / 10 ⁶ g, respectively. In Comparative Synthesis Example 6, the number average molecular weight was 6,500.

[0035]

[Table 1]

[0036]

[Table 2]

Example 1 A composition having the following composition ratio was placed in a ball mill and dispersed for 48 hours, and then 4 parts of coronate EH (trimer of hexamethylene diisocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added as a curing agent. The mixture was further mixed for 1 hour to obtain a magnetic paint. This was placed on a polyethylene terephthalate film having a thickness of 12 μm so that the thickness after drying became 4 μm.
Coating and drying were performed while applying a magnetic field of 00 Gauss. 50 ℃
After leaving for 2 days, the tape was slit to a width of 8 mm to obtain a magnetic tape. 100 parts of the polyesteramide solution obtained in Synthesis Example 1 (solvent cyclohexanone / methyl ethyl ketone / toluene = 1/1/1, solid content concentration 30%) Needle-shaped metal magnetic substance (BET 50 m ² / g) 120 parts Stearic acid 1 part Butyl stearate 0.5 part Alumina (average particle size 0.5 μm) 5 parts Toluene 150 parts Methyl ethyl ketone 100 parts The properties of the obtained magnetic tape are shown in Table-3.

Examples 2 to 11 Magnetic tapes were obtained in the same manner as in Example 1 except that the resins listed in Table 3 were used as binder resins. Table 3 shows the properties of the obtained magnetic tape. Comparative Examples 1 to 9 Using the polyesteramide resin, adipate-type polyurethane resin and vinyl chloride / vinyl acetate copolymer obtained in Comparative Synthesis Examples 1 to 6 in the proportions shown in Table 3, magnetic properties were obtained in the same manner as in Example 1. I got the tape. Table 4 shows the properties of the obtained magnetic tape. In Comparative Examples 2 and 6, the polyesteramide resin used was dissolved at a solid content of 8.6% and cyclohexanone / toluene / methylethylketone = 7.
It was dissolved at 80 ° C. in a 3 / 54.2 / 38.5 weight ratio. The resulting solution was cloudy. Example 1 using this solution
The magnetic paint worked as described above, but without the addition of toluene and methyl ethyl ketone. The magnetic paint was non-uniform due to the deposition of the resin component.

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

According to the present invention, a magnetic recording medium using an appropriate amount of a metal sulfonic acid salt and a polyesteramide resin containing an amide group according to the present invention as a binder component is BET-40 m ² / g.
It is excellent in the dispersibility of the above-mentioned fine magnetic particles, or magnetic particles such as metal magnetic powder and barium-ferrite, and provides high gloss and squareness of the magnetic coating film, and shows excellent durability. In the prior art, there was a problem that the gloss and the squareness ratio of the coating film were reduced with the improvement of the durability. However, the magnetic recording medium of the present invention enabled both high magnetic properties and high durability. It is.

Claims (1)

[Claims] (1) An ester bond and an amide bond are contained.
Ferromagnetic powder in binders containing polyesteramide resin
Coated magnetic paint containing non-magnetic on a non-magnetic support
In the recording medium, the polyesteramide in the binder
Resin is sulfone bonded to aromatic of dicarboxylic acid component
4 to 400 equivalent / 10 per acid metal base per polymer
⁶g, 100 to 3,000 amide bonds per polymer
Equivalent / 10 ⁶g and a number average molecular weight of 8,000
A magnetic recording medium characterized in that
body.