JPS62150529A - Magnetic metallic powder for magnetic recording and its production - Google Patents

Abstract

PURPOSE:To improve oxidation-resistant stability by depositing the condensation product of a specific polyalkylene polyamine on powder surface. CONSTITUTION:The condensation product of the polyalkylene polyamine expressed by the formula is deposited on the powder surface. The deposition treatment of a treating agent for deposition consisting of the condensation product of the polyalkylene polyamine on magnetic metallic powder is executed by dissolving the treating agent in a suitable solvent, wetting or immersing the magnetic metallic powder by using the prepd. soln. and evaporating the solvent. The solvent is exemplified by solvents which are inert to the magnetic metallic powder and can dissolved part or the whole of the treating agent, for example, benzene, butanol and water. The oxidation-resistant stability is thereby remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a metal magnetic powder suitable for magnetic recording with improved oxidation resistance stability and a method for producing the same.

(Technical background of the invention and its problems) Magnetic recording media such as magnetic tapes, magnetic disks, magnetic sheets, and magnetic cards for use in audio, video, and computers have recently become smaller due to increased recording density. , the trend towards higher performance is becoming stronger. In conjunction with this, in recent years, as magnetic powder for magnetic recording media, iron-based metal magnetic powder (hereinafter referred to as metal Magnetic powder) is attracting attention, and even higher S
With the demand for higher /N ratio and higher output, metal magnetic powder with fine particle size has been desired.

Incidentally, these metal magnetic powders have strong surface activity, and as a result, oxidation progresses over time, and as a result, the magnetic properties tend to be significantly impaired, and deterioration of so-called oxidation resistance cannot be avoided1). Furthermore, in severe cases, if the oxidation reaction in the air rapidly progresses to 29x, spontaneous ignition and even combustion may occur, causing various troubles in terms of handling and process control.

Various proposals have already been made to improve these problems. For example, a thin iron oxide film is formed by double oxidation of a metal magnetic powder immediately after it has been produced by reduction, or an inorganic substance such as chromium, silicon, or aluminum is coated on a metal magnetic powder, or even a mineral Attempts have been made to coat metal magnetic powder with various organic substances such as oil, silane coupling agents, and organic phosphate esters.

However, even with these conventional methods, oxidation-resistant stabilization is not sufficient, and while oxidation-resistant stabilization is achieved, the excellent magnetic properties of metal magnetic powders are easily deteriorated, so there are still problems that need to be improved. Many questions remain.

(Object of the Invention) An object of the present invention is to solve the above problems and provide a metal magnetic powder suitable for magnetic recording with excellent oxidation resistance and stability, and an industrially advantageous manufacturing method for the metal magnetic powder. .

(Structure of the Invention) As a result of various studies to solve the above-mentioned Z-point, the present inventors have discovered that a relatively small amount of treatment can be achieved by applying a specific polyamine compound to metal magnetic powder.
Therefore, it is possible to form a dense and stable film, and it has excellent oxidation resistance, stability, and ease of handling and dispersibility in a single magnetic recording medium without impairing the excellent magnetic properties inherent to the metal magnetic powder. The present invention was completed based on the knowledge that excellent metal magnetic powder could be obtained. That is, the first aspect of the present invention is a metal magnetic powder for magnetic recording, which is characterized by having improved oxidation resistance, which is obtained by coating the powder surface with a polyalkylene polyamine condensate represented by the following general formula.

General formula R1CON H(R2N R3)n R2N
HR- (wherein, R is an alkyl group or alkenyl group having 7 to 21 carbon atoms, R2 is C3H, or C, R5,
(R, is H or OCR1, n is an integer of 1 or more) Furthermore, the second aspect of the present invention is to use a solvent that is inert to the metal magnetic powder and can dissolve the polyalkylene polyamine condensate represented by the following general formula. This method of producing metal magnetic powder for magnetic recording with improved oxidation resistance stability is characterized in that the metal magnetic powder is wetted or immersed in a non-oxidizing atmosphere, and then the solvent is evaporated.

The metal magnetic powder used as the object to be treated in the present invention is an iron-based metal powder of iron or various iron-based alloys mainly made of iron produced by various methods. It has a crystalline shape with an average grain size (major axis length) of 0.15 to 0.5μ, an axial ratio of 2 to 20, and a specific surface area (Sg
) 20-80+n2/g, coercive force (He) 500-2
,000 (Oe) and saturation magnetization (ffs) 100-220
emu/g, but in addition to the above-mentioned needle-like crystals, there are various shapes such as spindle-like, rice-grain-like, spherical, rod-like, plate-like, dice-like shapes, and 68, He, σS, etc. fall within the above range. It may be something like that.

In the present invention, the polyalkylene polyamine condensate includes higher fatty acids such as capric acid, caprylic acid, lauric acid, myristic acid, palmitic acid, oleic acid,
Stearic acid, coconut fatty acid, beef tallow fatty acid, erucic acid, 1
2-Hydroxystearic acid, isostearic acid, impalmitic acid, etc. and polyalkylene polyamines such as diethylene Y-liamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, aminoethylaminopropylamine, triethylenetetraaminopropylamine From the viewpoint of economy and economy, it is preferable to use one obtained by reacting 1 to 2 moles of oleic acid, stearic acid, or palmitic acid with 1 mole of triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine to undergo dehydration condensation. Examples of such corporal punishment include (1)
C. H. ICONH (C2H.NH).

C2H. NH2, (2) C s H 1q C
ONH (C2H-NH)-C.
H4NHOCH11CI, (3)CIlH2)CONH
(C2H.NH)3C. H. NH2, (4)C. ,
H. , COonJH (C2H4NH), C2H. N.H.O.C.
H2. C1.

<5)C. , R3, CONH(C2H.NH)2C2H
．． NH2, (6) C1, R3. CONH (C.H.NH
), C2H4NH2, (7) C1, H1, CONH (C
2H4NH).

C2H. NHOCH1, C1, (8) C1, H1,
CoNH(C2H4NH)4 C2H4NH2,
(9) CI? HO) CONH (C.H.NH), C.H. H
6NH. , (1 0)C. , H1, CONHC2H. N(COC1
, H1,)C2H. NHC2H. NHOCC. , R35
, (1 1)ClsH31CoNH(C284NH)2
C2H,NH:,(1 2)C1,)(,5CONH
(C2H.NHLC2H4NHOCC, 7H, 5, etc. can be mentioned.

Note that these compounds may be used alone or as a mixture of two or more.

In the present invention, in order to apply the adhesion treatment agent made of the polyalkylene polyamine condensate to the metal magnetic powder, the treatment agent is dissolved in an appropriate solvent, and the solution is used to wet or immerse the metal magnetic powder. This can be done by evaporating the solvent. Suitable solvents include those that are inert to the metal magnetic powder and can dissolve part or all of the processing agent, such as benzene, toluene, xylene, kerosene, pyridine, acetonitrile, methyl ethyl ketone. , methyl butyl ketone, cyclohexanone, ethyl acetate, methanol, ethanol, butanol, water, etc., and these may be used alone or in combination of two or more thereof. Further, the wetting or immersion is performed in a non-oxidizing atmosphere, such as in a nitrogen gas, hydrogen gas, helium or argon gas atmosphere, or in a vacuum to prevent oxidation during the treatment. In addition,
The above-mentioned wetting or dipping treatment is usually carried out at room temperature, but may be carried out under heating if necessary.

Further, the processing time is usually about 10 to 300 minutes. Next, in order to leave the polyalkylene polyamine condensate on the surface of the metal powder and evaporate only the solvent, this can be done simply by air drying, but it is usually preferable to carry out heating or under reduced pressure. In the case of heat evaporation (1), the temperature is usually preferably 50 to 220°C, although this may vary depending on the type of solvent.

Incidentally, when the solvent is evaporated, it is preferably carried out in a non-oxidizing atmosphere. The amount of the treatment agent made of the polyalkylene polyamine condensate is:
The amount is 0.1 to 20%, preferably 0.5 to 10%, based on the weight of the metal magnetic powder. If the amount of adhesion is too small than the above range, the desired effect cannot be obtained, and if it is too large, the magnetic properties such as saturation magnetization may be easily damaged, or even a bleeding phenomenon may occur. This is undesirable because it deteriorates the performance of the magnetic coating film. Note that, prior to the deposition treatment of the polyalkylene polyamide condensate, the metal magnetic powder may be previously subjected to a treatment for forming an oxide layer, a nitride layer, an inorganic layer, or the like.

The present invention will be further explained below with reference to Examples.

Example 1 25 g of α-FeOOH needle crystal powder (average major axis length 0.2 μ, axial ratio 12) was heated in a Matsufuru furnace at 750° C. for 2 hours to obtain α-Fe, 03. After that, the obtained α-F
e20. 8 at 400°C in a tube furnace under a hydrogen gas stream.
Metallic iron powder (average major axis length 0.15μ,
Axial ratio 12, specific surface area (BET method) 55m2/g, Hc
1610 Oe, σsl 45 emu/g).

Next, into 100 ml of a solution prepared by dissolving the polyalkylene polyamine condensate O, Sg of the exemplary compound (7) as an adhesion treatment agent in toluene, the metallic iron powder 10 was added while blowing nitrogen gas, and while stirring, 2 hours at room temperature (25
After filtration, the powder was dried at 120°C in a nitrogen gas atmosphere to evaporate the solvent and deposit a polyalkylene polyamine condensate on the surface of the metal iron powder. (Sample A
) Example 2 The treatment was carried out in the same manner as in Example 1, except that 0.5 g of the polyalkylene polyamine condensate of the exemplary compound (6) was used as the adhesion treatment agent. (Sample B) Example 3 In Example 1, 0.5 g of a polyalkylene polyamine condensate consisting of a mixture (1:1) of the exemplified compounds (6) and (7) was used as the adhesion treatment agent. Other than that, the procedure was the same as for the ipsilateral side. (Sample C) Example 4 In Example 1, the exemplified compound (
8) Polyalkylene polyamine condensate 0. The treatment was performed in the same manner as the ipsilateral case, except that Sg was used.

(Sample D) Example 5 In Example 1, the exemplified compound (
The treatment was carried out in the same manner as in the case of the ipsilateral side, except that 0.58 of the polyalkylene polyamine condensate of 5) was used. (Sample E) Example 6 In Example 1, the exemplified compound (3
) and (4) (1:O,S) except that 0.5 g of a polyalkylene polyamine condensate was used. (Sample F) Example 7 In Example 1, the exemplified compound (
The treatment was carried out in the same manner as on the same side, except that 0.5 g of a polyalkylene polyamine condensate consisting of a mixture (1:0.5) of 1) and (2) was used. (Sample G) Comparative Example 1 In Example 1, the treatment was carried out in the same manner as in the same example except that the adhesion treatment agent was not overused. (Sample H) Comparative Example 2 In addition to using 0.58% of γ-glycidoxypropyltrimethoxylane as the adhesion treatment agent in Example 1, the same treatment as in Example 1 was carried out. (Sample I) Comparative Example 3 In Example 1, polyoxyethylene tridecyl ether phosphate phosphate ester 0 was used as the adhesion treatment agent.
．． The procedure was the same as in the same example except that 5 g was used. (Sample J) Table 1 shows the results of measuring the following characteristics for each sample obtained in Examples 1 to 7 and Comparative Examples 1 to 3.

Powder properties: Coercive force (Hc), saturation magnetization (σS)
), and the σ/σS ratio (σ: residual magnetization) was measured.

In addition, the sample powder was tested at 60°C and 80% relative humidity.
Measure the saturation magnetization value after leaving it for 4 days and find the rate of change over time Δ
Let σS (%) be an index of acid resistance and stability.

Sheet characteristics Two sample powders were dispersed in a beangu made of vinyl chloride-vinyl acetate copolymerized Honda fat as raw wood, and magnetic paint (PVC3S%) was prepared.
was prepared, and coated and oriented on a polyester film by a conventional method to produce a magnetic recording medium It (coating thickness: 8 μm).

The coercive force (Hc), retention EV richness (Br), and squareness ratio (SQ) of this recording point book were measured by conventional methods.

As is clear from the results in Table 1, the metal magnetic powder obtained according to the present invention has significantly improved oxidation resistance and good dispersibility in the +41 fat binder. Therefore, it is highly desirable because it eliminates the need for T-spinning magnetic recording media for high recording density.

(Effects of the Invention) The metal magnetic powder coated with 5-realkylene polyamine obtained by the present invention has significantly improved oxidation resistance, and therefore can maintain excellent magnetic properties for a long period of time. It itself has excellent storage stability and is highly desirable in terms of handling and process control;
Furthermore, it has good dispersibility into the medium and is extremely suitable for manufacturing high-output, high-density magnetic recording media. Further, according to the method of the present invention, the above-mentioned performance such as oxidation resistance and stability can be imparted with industrial advantages without impairing magnetic properties by relatively simple means.

Claims (1)

[Scope of Claims] 1) Metal magnetic powder for magnetic recording of general formula R characterized by improved oxidation resistance, which is obtained by coating the powder surface with a polyalkylene polyamine condensate represented by the following general formula:
_1CONH(R_2NR_3)_nR_2NHR_3
(However, in the formula, R_1 is an alkyl group or alkenyl group having 7 to 21 carbon atoms, R_2 is C_2H_4 or C_3H
_6, R_3 is H or OCR_1, n is an integer of 1 or more) 2) Non-oxidizing atmosphere using a solvent that is inert to metal magnetic powder and can dissolve the polyalkylene polyamine condensate represented by the general formula below. 1. A method for producing a metal magnetic powder for magnetic recording with improved oxidation resistance stability, which comprises wetting or immersing the metal magnetic powder in a medium and then evaporating a solvent. General formula R_1CONH(R_2NR_3)_nR_2N
HR_3 (wherein R_1 is an alkyl group or alkenyl group having 7 to 21 carbon atoms, R_2 is C_2H_4 or C_3H_6, R_3 is H or OCR_1, and n is an integer of 1 or more)