JP3491765B2 - Method for producing hematite particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to pigments, paints, catalysts, and paints.
Raw materials for ferrite, raw materials for magnetic iron oxide for magnetic recording media, etc.
Monodisperse spinner with very small particle size distribution
Method for producing conical hematite particlesIn particular, with fine particles
Monodisperse spindle type hematite particles with excellent particle size distribution
It relates to a method for manufacturing a child. [0002] 2. Description of the Related Art Magnetic recording technology requires repeated use of a medium.
It is possible to easily digitize signals and
It is possible to build a system by combining
There are no other recording methods, such as easy signal correction.
Video, audio,
Widely used in various fields including computer applications
Has been used. [0003] In addition, the miniaturization of equipment and the quality of recording / reproducing signals
To meet the demands for improved recording performance, longer recording times, and increased recording capacity, etc.
In order to respond to this problem, the
Improvements in layers have always been desired. For example, for audio and video applications
Is a digital recording system that improves sound and image quality
Development of recording system compatible with Hi-Vision TV
To address the need for shorter wavelengths than conventional systems
As magnetic recording media capable of recording and reproducing signals are required
It has become. Further, an external storage medium of a microcomputer or a personal computer
Having magnetic layer on flexible non-magnetic support
-In recent years, the spread of personal computers and applications
Of application software and processing information increase?
As high capacity as 10MB or more is strongly required
It has become. [0006] The magnetic recording medium has a magnetic layer on a non-magnetic support.
Tape, disk or car, depending on the application
And used in the form of And on the magnetic layer
Applies a coating solution in which ferromagnetic powder is dispersed on a non-magnetic support.
Mainly ferromagnetic powder obtained by drying the cloth and binder resin
So-called coating type magnetic layer and evaporation or sputtering
Vacuum deposition on non-magnetic support by vacuum deposition method such as
The so-called metal thin film type of ferromagnetic metal thin film obtained
There is a magnetic layer. From the viewpoint of recording density, the latter metal thin film type
The magnetic layer is excellent, and practical application has been studied for a long time.
And has been put to practical use for 8 mm video applications. However, a metal thin film type magnetic recording medium
Has characteristics problems in durability, running properties, corrosion resistance, etc.
Take full advantage of the original good properties to deal with the problem
Not done. In addition, the production cost is high and the economy is also a problem.
was there. On the other hand, a ferromagnetic powder and a binder resin are mainly used.
Coating type magnetism having a magnetic layer on a non-magnetic support
Recording media are more resistant than metal thin-film magnetic recording media.
Electromagnetic conversion characteristics, although excellent in durability, running properties and corrosion resistance
Increases the recording density of metal thin-film magnetic recording media
Many attempts have been made for this. For example, a method for enhancing the surface properties of a magnetic layer,
Method for improving the magnetic properties of magnetic powder, magnetism of ferromagnetic powder
This is a method of increasing the dispersibility in the layer. For example, in order to enhance magnetic properties, ferromagnetic powder
Use ferromagnetic ferromagnetic metal powder or hexagonal ferrite
Japanese Patent Application Laid-Open No. 58-122623,
No. 61-74137, Japanese Patent Publication No. 62-49656
Bulletin, JP-B-60-50323, US462965
No. 3, US4666770, US4543198, etc.
Is disclosed. In order to improve the dispersibility of the ferromagnetic powder,
In addition, various surfactants (for example, JP-A-52-15660)
No. 6, JP-A-53-15803, JP-A-53-15803
No. -116114. )
And various reactive coupling agents (for example,
JP-A-9-59608, JP-A-56-58135
And Japanese Patent Publication No. 62-28489.
You. ) Has been proposed. The above ferromagnetic metal powder or hexagonal ferrite
Is excellent as a ferromagnetic powder for high-density recording media
However, metal thin-film magnetic recording media have poor electromagnetic conversion characteristics.
The reality is that there is no way. In particular, hexagonal ferrite
Therefore, the saturation magnetization is small and the magnetic flux density of the magnetic layer is high.
There was a problem that could not be done. Also, its dispersibility is poor.
And it was difficult to obtain a magnetic layer having excellent surface properties. Further, the self-demagnetizing loss and the recording demagnetizing loss of the magnetic layer
As a method to reduce the loss and improve the recording density, the magnetic layer
The thickness of the ferromagnetic metal thin film type magnetic recording medium
The lower layer to ensure the flatness and strength of the magnetic layer
A magnetic recording medium provided with a relatively thick non-magnetic layer is disclosed in
7-198536, JP-A-62-154225
Gazette, JP-A-63-187428, JP-A-4-3
25915, JP-A-4-325916,
It is disclosed in Japanese Unexamined Patent Publication No.
Excellent output in the frequency range and close to a ferromagnetic metal thin film magnetic recording medium
Electromagnetic conversion characteristics were shown. However, the electromagnetic conversion characteristics
To improve the particle shape of the ferromagnetic powder as shown below
There was a problem with the condition and there was a limit. That is, a metal thin film type and a fine particle metal (ferromagnetic
Comparison of magnetic properties of coating media using metal) powder
Sometimes, SFD (Swit) of a coating type medium using metal powder
ching Field Destribution) is larger than metal thin film.
Recently, it was revealed that
On the other hand, Nakamura et al.
Simulation was performed to improve the distribution of anisotropic magnetic field.
Point out that shortwave output can be improved by improving
(Journal of the Japan Society of Applied Magnetics, Vol. 115, 155-158 (199
1)). Anisotropic magnetic field distribution has strong correlation with SFD,
When the sexual magnetic field distribution is large, the SFD (Hc distribution) becomes large. In ferromagnetic metal powder, Hc (coercive force) is
Is known to have a large effect on shape anisotropy.
Hc, which increases the particle size distribution of the ferromagnetic powder
Is also known to have a wide distribution. Because of this
Goethite, which is acicular particles used as a raw material for
Particle size distribution such as rapid crocite, hematite
Attempts to reduce the size are constantly ongoing. Te
To reduce surface roughness and improve short wavelength output
When using fine-grained ferromagnetic metal powder,
Variations in length have a large effect on Hc distribution
Was. As described above, compared with the conventional magnetic recording medium,
In order to further improve the recording density by improving the characteristics,
The particle size of the magnetic metal powder is small and the particles
It is desirable that the size and shape be as uniform as possible. So
Each particle is well separated and the particle size distribution is non-
Particles that are always small are called monodisperse particles. Particle rhinoceros
Monodisperse to study size and catalyst performance and particle-particle interactions
Research into synthesizing particles (eg, surface,
29, 978 (1991) and 23, 177 (198)
4)). The method of synthesizing monodisperse spindle type hematite is as follows:
M. Ozaki et al. Colloid Inte
rface Sci. 102 146-151 (198
It is reported in 4). They use 0.
02 mol of ferric chloride and 1.0 × 10^-Four~ 4.0 × 10
^-FourMolar NaH_Two PO_Four Or NaH_Two PO_Two Contains
Liquid at 100 ± 2 ° C. for 2 days and a particle length of 0.1
2 to 0.55 µm, particles with a needle ratio of 2 to 5.5 are synthesized
I have. As a second method, sodium hydroxide is added to ferric nitrate.
Add ferric hydroxide to make ferric hydroxide, repeat washing with distilled water,
0.02 mol of ferric hydroxide 200cm^Three 5-20 in
cm^Three 0.5N to 2.5cm with 1N HCl^Three 0.1
M NaH_TwoPO_Four Is added and the whole is distilled water 500c
m^Three And kept at 100 ± 2 ° C. for 2 days, particle length 0.2
Particles with a needle ratio of 3 to 6 having a particle size of 7 to 0.33 μm are synthesized.
You. Ferric chloride and NaH to increase yield_Two PO_Four Also
Or NaH_Two PO_Two ΒFeOOH increases the concentration of
Contaminated, unable to obtain single phase monodisperse spindle type hematite
It is reported. M. Ozaki et al. Obtained the monodisperse spindle type.
Hematite is reduced with hydrogen at 340 to 400 ° C for 1 to 3 hours.
Next, let air flow and oxidize at 240 ° C for 1 to 2 hours_Two O
_Three And J. Colloid Interfac
e Sci. 107 199-203 (1985)
Tells. Also, one of the inventors is extremely rich first
Fe (OH)_Three Gel (about 1 mol / l) as starting material
And a pseudo-cube (average) through the intermediate product βFeOOH
Monodisperse hematite particles having a particle size of about 2 μm) were synthesized.
(J. Colloid Interface Sci.
152, 587 (1992)). M. The method of Ozaki et al. Is a monodisperse spindle type.
Hematite to γFe_Two O_Three But monodisperse spindle
Monodisperse due to the low concentration of the reaction solution that produces hematite
Low yield of spindle type hematite
I can't. J. Colloid Interf
ace Sci. 152 587 (1992)
Does not produce spindle-type hematite and produces fine particles.
I can't. Further, a fine monodisperse spindle type as described above
Creates hematite particles, which provide runnability, durability and protection
Excellent practical characteristics such as viability and economic efficiency, and electromagnetic conversion characteristics
Ferromagnetic powder suitable for high-density magnetic recording media
It is desired to obtain a magnetic recording medium of the coating type.
Electromagnetic that can be comparable to thin metal magnetic recording media
It is desired to obtain a magnetic recording medium having a conversion characteristic
I have. [0020] SUMMARY OF THE INVENTION The present invention relates to the above prior art.
In view of the above problem, the first aspect of the present invention
The purpose is that the average particle length is 1 μm or less and the acicular ratio is 2 to 8.
For industrially producing monodisperse spindle type hematite particles
Is to provide. [0021] [0022] Means for Solving the Problems One of the inventors is an iron oxide.
As a result of repeated studies on the production method of
Hydrolysis of ferric hydroxide in the presence of
Hematite monodisperse particles with higher concentration than by the method
Thus, the invention of the following production method has been accomplished. So
Then, the present inventors made a magnetic recording using hematite as a raw material.
Production method of ferromagnetic powder used as raw material for medium
As a result of the investigation, the obtained ferromagnetic powder was
It has been found that it has optimal properties as a raw material for recording media
The invention of the following ferromagnetic powder and magnetic recording medium is described.
It has come. That is, the object of the present invention is to provide a sulfate ion
(S0_Four ^2-) Or hydroxylation in the presence of phosphate ions
Hematite microparticles as nuclei in ferric gel suspension
After dispersing, the ferric hydroxide is hydrolyzed.
Of monodisperse spindle type hematite particles by usingAnd
Sulfate ion in the gel suspension of ferric hydroxide
Concentration of 0.01 mol / L to 0.1 mol / L
Or the concentration of phosphate ions is 0.001 to
0.01 mol / liter, which is used as the nucleus.
Particle diameter of hematite fine particles is 30 to 200 Å
Monodisperse spindle type hematite characterized by loam
Method for producing particles(Claim 1), the method according to claim 1.
The monodisperse spindle type hematite particles obtained in
After the netite is formed, the magnetite is oxidized to form FeO.
_X(1.33 <x ≦ 1.5) ferromagnetic acid
A method for producing iron fossil, obtained by the method according to claim 1 described above.
Reduced monodisperse spindle type hematite particles
After reducing the magnetite
Method for producing magnetic metal powder, and ferromagnetic on non-magnetic support
Magnetic recording with magnetic layer mainly composed of powder and binder resin
In a medium, the ferromagnetic powder is obtained by the method described above.
Ferromagnetic iron oxide or ferromagnetic obtained by the method described above
This is achieved by a magnetic recording medium that is a metal powder. Further
In addition, the above sulfate ion (S0_Four ^2-) Or phosphate ion
Hematite in a gel suspension of ferric hydroxide in the presence of
After the fine particles are dispersed as nuclei, the ferric hydroxide
Spindle type hematite particles by hydrolysis of
In the suspension of the ferric hydroxide gel during the production of
The concentration of sulfate ions is 0.01 mol / liter to 0.1 mol / l.
1 mol / liter or the concentration of phosphate ions
0.001 to 0.01 mol / liter
More effective, monodisperse and fine-particle spindle type hematite
Particles can be produced. The above-mentioned claim 1
Monodisperse spindle type hematite particles obtained by the method described in
After reduction to magnetite, the magnetite is acidified.
FeO_XFerromagnetic (1.33 <x ≦ 1.5)
The method for producing iron oxide or the method according to claim 1.
The monodisperse spindle type hematite particles obtained by the
Reducing the magnetite after making it magnetite
Ferromagnetic iron oxide
Or when manufacturing ferromagnetic metal powder, use monodispersed spindle type
Annealing hematite particles or magnetite
Makes crystal growth more complete and has excellent magnetic properties
Ferromagnetic powder can be obtained. In addition, a ferromagnetic powder is bonded on a non-magnetic support.
Providing a magnetic layer mainly comprising an agent resin, the ferromagnetic powder,Up
RecordFerromagnetic iron oxide obtained by the method orthe aboveObtained in the way
Layer structure of a magnetic recording medium that is
Nonmagnetic layer mainly composed of conductive powder and binder resin, and strong
A magnetic layer mainly composed of a magnetic powder and a binder resin;
A thin-film magnetic layer whose thickness is 1.0 μm or less;
By doing so, the features of the ferromagnetic powder according to the present invention
High density recording with high output, especially at short wavelengths
To obtain a magnetic recording medium suitable as a magnetic recording medium for
You can. Further, the present inventors have found that the above steps
Therefore, even if phosphate ions are used instead of sulfate ions,
Finding to obtain similar monodisperse spindle type hematite particles
Was. Further, the present inventors have prepared the above monodisperse spindle type hemata.
To obtain ferromagnetic powder for magnetic recording using magnetic particles
As a result of reducing the monodisperse spindle type hematite particles
The magnetite and oxidize or reduce it.
Due to the small particle size distribution, ferromagnetic for magnetic recording
The powder was successfully obtained. In particular, the above monodisperse spindle type hematite particles
Is polycrystalline, so the obtained monodisperse spindle type hematite grains
The particles are reduced in hydrogen to form magnetite, which is simply
Simply oxidized or reduced does not necessarily have excellent magnetic properties
Monodisperse spindle type hematite particles
Prior to the reduction, this may be annealed or reduced.
To magnetite and then annealing.
To obtain ferromagnetic powder with significantly improved magnetic properties
succeeded in. Further, the ferromagnetic material annealed as described above
By using conductive powder, magnetic properties with extremely excellent magnetic properties
Succeeded in obtaining a recording medium, especially as the ferromagnetic powder
Using ferromagnetic metal powder, multi-layer structure, upper layer thickness
A magnetic layer having a thickness of 1.0 μm or less, and a lower layer serving as a nonmagnetic layer
As a result, magnetic properties comparable to the thin metal (evaporated type)
The recording medium was successfully obtained by coating. That is, the first invention of the present application relates to a sulfate group.
Ion (S0_Four ^2-) Or hydroxyl in the presence of phosphate ions
Hematite Fine Particles as Nucleic Crystals in Ferric Chloride Gel Suspension
After dispersing the ferric hydroxide, a single component hydrolyzing the ferric hydroxide
A method for producing spun spindle type hematite particles,
Concentration of sulfate ion in the gel suspension of ferric bromide
0.01 mol / l to 0.1 mol / l
Or the concentration of phosphate ions is 0.001 to 0.01
Per liter,NucleusHemataie used as
The fine particles have a particle size of 30 to 200 angstroms.
Of monodisperse spindle type hematite particles characterized by the following:
Is the way. [0029] [0030] [0031] The ferromagnetic powder according to the present invention is characterized in that
Maintains the monodispersity characteristic of conical hematite particles
And SFD (sw
Good pitching field distribution and coercive force (H
c) Narrow distribution, so when used for magnetic recording media
In particular, recording demagnetization loss is improved, and short wavelength recording characteristics are excellent.
It has the feature that it is. Hereinafter, the present invention will be described in detail. In the present invention
Monodisperse refers to particles with a sharp particle size distribution.
The size distribution spread is a standard for the average size
The deviation is within 10% at most. Hydroxylation used
The concentration range of the ferric gel is limited by the solubility of the ferric salt.
If the viscosity of the obtained gel is too high, stirring becomes difficult.
Therefore, the content is preferably 2 mol / liter or less. concentration
Although monodispersed spindle type hematite can be obtained even if
From the economic point of view
The lower limit of the degree is determined. NaOH etc. at the time of adjusting the hydroxide gel
The amount of alkali added is Fe³⁺Intermediate product if not less than
Β-FeOOH is not obtained and hematite is formed
Also do not monodisperse. To obtain hematite with high monodispersity
For example, Fe³⁺The excess concentration of ions is 0.05-0.2
Is preferable. Note that the present invention
In the gel suspension of the ferric hydroxide of the sulfate group,
Concentration of 0.01 mol / l to 0.1 mol / l
TorrAnd preferably0.015 to 0.08 mol / l
It is preferably a title. Further, the concentration of the phosphate group is 0.1.
001 to 0.01 mol / lYes, preferably
It is 0.0015 to 0.008 mol / liter. What
When a phosphate ion is used in the present invention, the phosphate ion
As PO_Four ^3-, H_Two PO^Four-Or HPO^2-In the form of
Can be. Ferric hydroxide used as nucleus
The particle size of the hematite fine particles obtained by hydrolysis is 30.
~ 200 Å is preferred. Small particle size
If it is too small, the effect as a nucleus will be noticeable, if too large,
Monodisperse spindle type hematite of fine particles cannot be obtained. Nuclear
It is effective to make the particle size distribution uniform.
Crushed by mechanical force to remove coarse particles before use
Is desirable. Nucleated crystals added to ferric hydroxide gel and hydrolyzed
If the reaction rate is too high when reacting, new nucleation will occur.
In some cases, monodispersed particles cannot be obtained. Renucleation
It is necessary to set the temperature, pressure and time within a range that does not occur.
You. The present inventors have obtained the above as described above.
The use of monodisperse spindle type hematite fine particles provides excellent magnetic properties.
To obtain ferromagnetic powder for magnetic recording that has magnetic properties
I found that. When manufacturing ferromagnetic iron oxide powder
Reduces and oxidizes the obtained monodisperse spindle type hematite particles.
Effective to prevent hematite from sintering before
Silica, phosphoric acid, aluminum-silicon
Mosquito, or a combination of these can be used
You. The amount of the sintering inhibitor used is relative to hematite.
And preferably 0.05 to 3.0% by weight, more preferably
0.1 to 1.5% by weight. Insufficient amount of sintering inhibitor
The shape retention effect is poor when reducing and oxidizing, and too much
The saturation magnetization decreases, and the magnetic properties of the resulting ferromagnetic powder
The characteristics deteriorate. The above monodisperse spindle type hematite particles
To make ferromagnetic iron oxide powder from
After reduction to magnetite, the magnetite is acidified.
To become FeOx (1.33 <x ≦ 1.5)
Iron oxide. In the present invention, even if
A ferromagnetic powder with good magnetic properties can be obtained,
Monodisperse spindle type hematite particles are polycrystalline,
Reduced monodisperse spindle type hematite particles in hydrogen
No magnetite, just oxidized or reduced
Is not always possible to obtain ferromagnetic powder with excellent magnetic properties.
Before reducing monodisperse spindle type hematite particles,
This is annealed or reduced to magnetite
Ferromagnetic acid obtained by annealing after
Significantly improve the magnetic properties of ferrous and ferromagnetic metal powders.
Can be. If annealing is performed prior to reduction,
Neal temperature is preferably 450 to 800 ° C and 500 to 75.
0 ° C. Annealing time is preferably about 1 to 5 hours
It is desirable that the selection be made in relation to the processing temperature. Long at high temperature
If the annealing time is too long, the particle shape will change.
U. Well-known hydrogen gas reduction is a method of reducing particles
Process, thermal decomposition of organic matter in inert gas
A method using an original gas or the like can be used. Mug
When annealing after netting, use hematite
Can be processed at a slightly lower temperature than when processing with
Desirably, treatment at 400-600 ° C is preferred
No. After the reduction, air is flowed at 200 to 300 ° C.
Fe_TwoO_Three In addition, FeOx (1.
33 <x ≦ 1.5). Adjust oxidation degree
As a method of adjusting, the oxygen concentration in the oxidizing gas was lowered
The oxidation temperature should be 60-150 ° C.
It can be adjusted. After magnetic iron oxide, the surface
A known method is used to deposit a Co compound on
Can be used. These methods are described in, for example,
49-74399 and 50-37667. Tokunosho 4
No. 9,49,475. Monodisperse spindle type hematite obtained by the present invention
Is converted to ferromagnetic metal (alloy) powder to prevent sintering.
It is necessary to treat with a blocking agent.
1, Si, Al-Si, B, Ca, Nd, Y, La, etc.
You can use well-known ones and their combination
it can. The treatment amount of the sintering inhibitor is 1-2
0 atomic% is preferable, and 3 to 15 atomic% is more preferable.
It is. The method of applying the sintering inhibitor should be
Element used to disperse matite particles in water and prevent sintering
By adding an aqueous solution of a compound containing
Deposits on the surface of the particles, washing with water and removing impurities.
Removal is preferred. Improved magnetic properties and weather resistance
For best results, apply metal elements before treating with a sintering inhibitor.
It is also preferable to form an alloy after reduction by attaching.
Elements used for the deposition process include Co, Ni, Mn,
Cu, Sn, Cr, Sb, Nd, Y, La, Sc, B
a, Sr, Ca, etc., used alone or in combination
May be. The amount of metal used for alloying is
Although it depends on the possible composition range, generally, it is 0.1 to 30 weights.
%. If it is a non-magnetic alloy, add too much
However, the amount of transition metals such as Co and Ni
It can be changed in the range of 0.1 to 30% by weight.
Co has the effect of increasing the saturation magnetization and improving the weather resistance,
It is a preferred additive element. On the other hand, Ni promotes reduction
Since it is an element, it can be reduced at low temperatures and has a shape-retaining effect
It is an element that is effective in terms of fruit. Hydrogen is used to reduce to metal,
Reduction at 50 to 550 ° C, preferably 400 to 500 ° C
You. The progress of the reduction is determined by measuring the moisture in the hydrogen gas after the reduction with a dew point meter.
It can be determined by monitoring where. Ferromagnetic gold obtained
It is necessary to oxidize and stabilize the surface of the genus powder. For this reason
After the reduction is completed, a gas with controlled oxygen
Slowly oxidize the surface by passing oxygen-containing gas through the solvent
I do. In this case, monitor the calorific value with a thermometer,
Avoid oxidation. Gas used for slow oxidation
It is desirable that the water content is as low as possible. Also,XuOxidize
Before being described in JP-A-63-52327.
After treatment with the compound,XuOxidation can also saturate the ferromagnetic powder.
This is effective in increasing the sum magnetization σs. The magnetic recording medium of the present invention has a single magnetic layer.
Even conventional magnetic recording media using ferromagnetic powder
The short wavelength output reflects the superior SFD compared to
Are better. Also, a coating layer formed on a non-magnetic support
Are ferromagnetic powders dispersed in a binder or non-magnetic powders
Is dispersed in a binder, and 1 μm is applied to the uppermost layer.
The one using a magnetic layer with the following thickness increases short-wavelength output.
In addition, a magnetic recording medium with higher performance than a single-layer
You. When two or more coating layers are formed on a non-magnetic support,
The first coating layer on the non-magnetic support is
Apply the second layer coating solution on the surface while it is wet
So-called wet-on-wet method (simultaneous multilayer coating)
Cloth method, JP-A-61-139929, JP-A-61-139929
No. 61-54992).
That is, while the first coating layer is in a wet state, the upper magnetic layer
Can be applied to form a thin upper magnetic layer.
Easier, and coating defects can be reduced.
In addition, it is possible to increase the adhesion to the magnetic layer.
Good. In the magnetic recording medium of the present invention, the coating layer
The above-described ferromagnetic powder of the present invention is used for the uppermost layer provided with two or more layers.
The reason is to maximize the high density magnetic recording performance
First, the practical characteristics of magnetic recording media
Non-magnetic powder such as carbon black required for
Short-wavelength because the necessary electrical conductivity can be secured by adding
1 μm or less of the uppermost layer of the magnetic recording medium important for magnetic recording
Increasing the saturation magnetic flux density per unit volume of the part
Second, the surface of the uppermost layer can be smoothed.
It is because it is finished easily. In addition, monodisperse as a material
Use of relatively expensive ferromagnet reduced from spindle type hematite
There is also an economic advantage as the dose can be reduced. The formation of the magnetic layer in the magnetic recording medium of the present invention
The mixture resin is a thermoplastic resin conventionally used in this field.
Resins, thermosetting resins, reactive resins and their mixtures
Can be used. As a thermoplastic resin, the glass transition temperature is
-100 to 150 ° C, number average molecular weight of 1,000 to 2
00000, preferably 10,000 to 100,000,
The degree of polymerization is about 50 to 1,000. As such a binder resin, vinyl chloride
, Vinyl acetate, vinyl alcohol, maleic acid,
Curric acid, acrylic acid ester, vinylidene chloride,
Rilonitrile, methacrylic acid, methacrylic acid ester,
Styrene, butadiene, ethylene, vinyl butyral,
Vinyl acetal, vinyl ether, etc. as structural units
Containing polymers or copolymers, polyurethane resins, various
There are rubber-based resins. Further, a thermosetting resin or a reactive resin may be used.
Phenol resin, epoxy resin, polyurethane cured
Mold resin, urea resin, melamine resin, alkyd resin,
Ril-based reaction resin, formaldehyde resin, silicone tree
Fat, epoxy-polyamide resin, polyester resin
Mixture of socyanate prepolymer, polyester poly
A mixture of polyol and polyisocyanate, polyurethane and
And mixtures of polyisocyanates. In the above binder resin, more excellent ferromagnetic powder
It is necessary to obtain the dispersion effect of the powder and the durability of the magnetic layer.
, COOM, SO_ThreeM, OSO_ThreeM, P = O (O
M)_Two, OP = O (OM)_Two, (M is a hydrogen source
OH, NR_Two, N⁺R_Three
(R is a hydrocarbon group) from epoxy group, SH, CN, etc.
 Copolymerizing at least one or more polar groups selected or
Is preferably those introduced by an addition reaction.
The amount of such polar groups is 10^-1To 10^-8Mol / g
And preferably 10^-2To 10^-6Mol / g. Binder used in the magnetic recording medium of the present invention
The resin is in the range of 5 to 50% by weight based on the ferromagnetic powder,
Preferably, it is used in the range of 10 to 30% by weight. salt
5 to 100% by weight when vinyl chloride resin is used.
When using a urethane resin, 2 to 50% by weight
Liisocyanate is used in an amount of 2 to 100% by weight.
Are preferably used in combination. The filling degree of the ferromagnetic powder in the magnetic layer is determined by
Saturation magnetization σs and maximum magnetic flux density of used ferromagnetic powder
Can be calculated from the degree Bm (Bm / 4πσs).
In this case, the value is desirably 1.7 g / cc or more.
And more preferably 1.9 g / cc or more, most preferably
Is 2.1 g / cc or more. In the present invention, when polyurethane is used,
If the glass transition temperature is -50 ~ 100 ℃, elongation at break
100-2000%, breaking stress 0.05-10k
g / cm^Two, Yield point is 0.05-10kg / cm^TwoIs good
Good. The polyisocyanate used in the present invention
And tolylene diisocyanate, 4-4'-diphenyl
Methane diisocyanate, hexamethylene diisocyanate
Nate, xylylene diisocyanate, naphthylene
1,5-diisocyanate, o-toluidine diisocyanate
Neato, isophorone diisocyanate, triphenylmeth
Isocyanates such as tantriisocyanate,
Formation of these isocyanates and polyalcohol
Products and polyisocyanates
Liisocyanate and the like can be used. these
Commercially available trade names of isocyanates include
Polyurethane Co., Coronate L, Coronate HL,
CORONATE 2030, CORONATE 2031, Millionet
MR Millionet MTL, Takeda Pharmaceutical, Takenet
D-102, Takenate D-110N, Takenate D-
200, Takenet D-202, manufactured by Sumitomo Bayer, Inc.
SModule L, Desmodule IL, Desmodule
N Desmodul HL, etc.
Two or more combinations utilizing the difference in
You can use it. In the magnetic layer of the magnetic recording medium of the present invention,
Normally, lubricants, abrasives, dispersants, antistatic agents, dispersants,
Elements with various functions including plasticizers, fungicides, etc.
The material is contained according to the purpose. As a lubricant used in the magnetic layer of the present invention
Is a dialkylpolysiloxane (alkyl has 1 carbon atom)
To 5), dialkoxypolysiloxane (alkoxy is
C1-C4), monoalkyl monoalkoxy poly
Siloxane (alkyl has 1 to 5 carbon atoms, alkoxy
Is 1 to 4 carbon atoms), phenylpolysiloxane,
Polyalkylpolysiloxane (alkyl has 1 to 5 carbon atoms)
Silicone oil; conductive fine particles such as graphite
Powder; molybdenum disulfide, tungsten disulfide, etc.
Machine powder; polyethylene, polypropylene, polyethylene
Vinyl chloride copolymer, polytetrafluoroethylene, etc.
Plastic fine powder of α-olefin polymer at room temperature
Liquid unsaturated aliphatic hydrocarbon (n-olefin double bond
Is a compound having about 20 carbon atoms bound to the terminal carbon;
12 to 20 monobasic fatty acids and 3 to 12 carbon atoms
Fatty acid esters consisting of
Orocarbons and the like can be used. Among them, fatty acid esters are more preferable.
Ethanol is the raw material for fatty acid esters.
Knol, butanol, phenol, benzyl alcohol
, 2-methylbutyl alcohol, 2-hexyldecyl
Alcohol, propylene glycol monobutyl ether
, Ethylene glycol monobutyl ether, dipropyl
Len glycol monobutyl ether, diethylene glyco
Monobutyl ether, s-butyl alcohol, etc.
Monoalcohols, ethylene glycol, diethylene glycol
Recall, neopentyl glycol, glycerin, sol
And polyhydric alcohols such as bitane derivatives. Same
Fatty acids include acetic acid, propionic acid, octanoic acid, 2-
Ethylhexanoic acid, lauric acid, myristic acid, steer
Phosphoric acid, palmitic acid, behenic acid, arachidic acid, oleic
Acid, linoleic acid, linolenic acid, elaidic acid, palmi
Aliphatic carboxylic acids such as toleic acid or mixtures thereof
Is mentioned. A specific example of the fatty acid ester is butyl.
Stearate, s-butyl stearate, isopropyl
Stearate, butyl oleate, amyl stearate
G, 3-methylbutyl stearate, 2-ethylhexyl
Rustearate, 2-hexyldecyl stearate,
Chill palmitate, 2-ethylhexyl myristate,
A mixture of butyl stearate and butyl palmitate,
Toxylethyl stearate, 2-butoxy-1-propion
Rustearate, dipropylene glycol monobutyl ether
Acylated with stearic acid, diethylene
Glycol dipalmitate, hexamethylene diol
Acrylic acylated with myristic acid,
List of various ester compounds such as oleate of serine
be able to. Further, when the magnetic recording medium is used under high humidity
Reduce the hydrolysis of fatty acid esters that often occur
Of fatty acids and alcohols as raw materials
Select chain, isomer structure such as cis / trans, branch position
Is done. These lubricants are 100 parts by weight of binder
In the range of 0.2 to 20 parts by weight. The following compounds are further used as lubricants
You can also. That is, silicon oil, graphite
G, molybdenum disulfide, boron nitride, graphite fluoride, fluorine
Alcohol, polyolefin, polyglycol, alk
And phosphoric acid esters and tungsten disulfide. As an abrasive used in the magnetic layer of the present invention,
Is a commonly used material, fused alumina, silicon carbide,
Chromium oxide (Cr_Two O_Three ), Corundum, artificial coranda
, Diamond, artificial diamond, garnet, ame
Lee (main component: corundum and magnetite) is used.
These abrasives have a Mohs hardness of 6 or more. concrete
Examples are AKP-10 and AKP-1 manufactured by Sumitomo Chemical Co., Ltd.
2, AKP-15, 20AKP-30, AKP-50,
AKP-1520, AKP-1500, HIT-50,
HIT60A, HIT-100, manufactured by Nippon Chemical Industry Co., Ltd., G
5, G7, S-1, chromium oxide K, Uemura Kogyo UB
40B, WA8000, WA1000 manufactured by Fujimi Abrasives Co., Ltd.
0, Toda Kogyo TF140, TF180, etc.
It is. With an average particle size of 0.05 to 3 μm
Is effective, and preferably 0.05 to 1.0 μm.
You. These abrasives are used for 100 parts by weight of the magnetic material.
1 to 20 parts by weight, preferably 1 to 15 parts by weight.
Add in box. If less than 1 part by weight, sufficient durability
If not more than 20 parts by weight, the surface properties and the filling degree
to degrade. These abrasives are pre-dispersed with a binder.
After processing, it may be added to the magnetic paint. In the magnetic layer of the magnetic recording medium of the present invention,
Contain conductive particles as antistatic agent in addition to non-magnetic powder
You can also. However, the saturation flux density of the top layer
To the maximum layer as much as possible to maximize
It is preferable to add it to the coating layer other than the top layer.
New In particular, carbon black is added as an antistatic agent.
Addition is advantageous in reducing the surface electrical resistance of the entire medium.
Good. Carbon black that can be used in the present invention is for rubber
Furnace, thermal for rubber, black for color, conductive
Use carbon black, acetylene black, etc.
Can be. Specific surface area is 5 to 500m^Two/ G, DBP
Oil absorption is 10 ~ 1500ml / 100g, particle size is 5
m to 300 mμ, PH is 2 to 10, and water content is 0.
1 to 10%, tap density 0.1 to 1 g / cc,
preferable. Specific examples of carbon black used in the present invention
A typical example is BLACKPEARL manufactured by Cabot Corporation.
S2000, 1300, 1000, 900, 800, 7
00, VULCAN XC-72, manufactured by Asahi Carbon Co., #
80, # 60, # 55, # 50, # 35, Mitsubishi Chemical
# 3950B, # 3250B, # 2400B, #
2300, # 900, # 1000, # 30, # 40, #
10B, CONDUCTE, manufactured by Konlon Via Carbon
X SC, RAVEN 150, 50, 40, 15, LA
Ion Aguso Ketjen Black EC, Ketjen
Black ECDJ-500, Ketchen Black ECD
J-600 and the like. Carbon black
Surface treatment with a dispersant or carbon black.
Even if oxidized or grafted with resin,
It is also possible to use a part of the surface that has been graphitized.
Absent. Before adding carbon black to the magnetic paint
May be dispersed in advance with a binder. For magnetic layer
When carbon black is used, the amount based on the magnetic material is
It is preferable to use 0.1 to 30% by weight. Further
The non-magnetic layer contains 3 to 20% by weight of the total non-magnetic powder.
It is preferred to have. Generally, carbon black is used as an antistatic agent.
As well as friction coefficient reduction, light-shielding properties, and film strength
It has the above functions, and these are the carbon blacks used.
Depends on Therefore, these cars used in the present invention
Bon Black changes its type, amount, and combination, and
Characteristics such as noise, oil absorption, conductivity, and PH
It is of course possible to use them properly according to the purpose.
You. Carbon black that can be used is, for example, "Carbon
Rack Handbook ", Carbon Black Association Edition
Can be. The non-magnetic layer under the magnetic layer of the magnetic recording medium of the present invention
When forming a magnetic layer, the non-magnetic layer combines non-magnetic powder.
This is a layer dispersed in the resin. Used for its non-magnetic layer
Various non-magnetic powders can be used. For example,
α-alumina, β-alumina, γ-
Alumina, silicon carbide, chromium oxide, cerium oxide, α
-Iron oxide, corundum, silicon nitride, titanium carbide,
Titanium oxide, silicon dioxide, boron nitride, zinc oxide, carbonic acid
Calcium, calcium sulfate, barium sulfate etc. alone
Or used in combination. Particle size of these non-magnetic powders
The size is preferably 0.01 to 2 μm, but if necessary,
Combine non-magnetic powders with different
Even with non-magnetic powders, the same effect can be achieved by broadening the particle size distribution.
You can also. Great interaction with the binder resin used
In order to improve the dispersibility, the non-magnetic powder used
Surface treatment may be applied. As surface treatment products, silicon
Treatment with inorganic substances such as mosquito, alumina, silica-alumina
Or treatment with a coupling agent. Tap dense
The degree is 0.3 to 2 g / cc and the water content is 0.1 to 5 weight.
%%, pH 2-11, specific surface area 5-100m^Two
/ G is preferred. The shape of the non-magnetic powder is acicular, spherical
The shape may be any of a shape, a die shape, and a plate shape. Used in the present invention
Examples of non-magnetic powders that can be used include Sumitomo Chemical
AKP-20, AKP-30, AKP-50, HI
T-50, manufactured by Nippon Chemical Industry Co., Ltd., G5, G7, S-1, door
TF-100, TF-120, TF-14
0, Ishihara Sangyo TT055 series, ET300W,
TTT30, ferromagnetic iron oxide and ferromagnetic gold
Hematite particles, which are intermediate raw materials for metal powders
You. The magnetic recording medium of the present invention has a strong
When forming a magnetic layer, the ferromagnetic material
Iron oxide, cobalt-modified ferromagnetic iron oxide, CrO_Two, Hexagon
Crystal ferrite, various metal ferromagnet dispersed in resin,
Various things can be used Forming two or more coating layers on a non-magnetic support
The wet-on-weather method described above.
As a specific method of the cut method, (1) Gravity commonly used in magnetic paints
Coating, roll coating, blade coating, extrusion
The lower layer is first applied by a coating device and the layer is still wet
While in the state, for example, Japanese Patent Publication No. 1-46186
And Japanese Unexamined Patent Publication No. 60-238179 and
Non-magnetic support pressurizing type disclosed in Japanese Patent No. 65672
Those who apply the upper layer by extrusion coating equipment
Law, (2) JP-A-63-88080,
JP-A-2-17971 and JP-A-2-265672
No. 2, the slit for passing the coating liquid as disclosed in
With the built-in coating head, the lower layer coating solution and the upper layer
A method of applying the coating liquid almost simultaneously, (3) disclosed in JP-A-2-174965
Extrusion with backup rolls
For applying the upper and lower layers almost simultaneously by using a coating device
Method, and the like. Coating by wet-on-wet method
In this case, the flow characteristics of the coating solution for the magnetic layer and the coating solution for the non-magnetic layer
The one as close as possible is the boundary between the applied magnetic layer and the non-magnetic layer.
A magnetic layer with uniform thickness and uniform thickness with little surface fluctuation
Obtainable. The flow characteristics of the coating liquid
Because it strongly depends on the combination of the powder particles and the binder resin,
Pay particular attention to the selection of non-magnetic powder used for the non-magnetic layer
There is a need. The non-magnetic support of the present magnetic recording medium is usually
1 to 100 μm, preferably 3 to 20 μm, non-magnetic
The thickness of the layer is 0.5 to 10 μm. In addition,
The layers other than the magnetic layer and the non-magnetic layer may be formed according to the purpose.
Forming the magnetic layer as the uppermost layer,
It is permissible as long as the configuration is such that the layer is the layer below it. For example,
Undercoat layer to improve adhesion between nonmagnetic support and underlayer
May be provided. This thickness is 0.01 to 2μ
m, preferably 0.05 to 0.5 μm. Also,
A back coat layer is provided on the side opposite to the magnetic layer side of the non-magnetic support.
It may be provided. This thickness is 0.1 to 2 μm,
More preferably, it is 0.3 to 1.0 μm. Between these
Known layers and backcoat layers can be used. Disk shape
In the case of a magnetic recording medium, the above-described layer structure is formed on both sides or both sides.
Can be provided. The non-magnetic support used in the present invention is particularly
There are no restrictions, and you can use the ones that are normally used.
Wear. Examples of the material forming the non-magnetic support include poly
Ethylene terephthalate, polyethylene, polypropylene
, Polycarbonate, polyethylene naphthalate, polycarbonate
Lamide, polyamide imide, polyimide, polysulfo
Filling of various synthetic resins such as polyethersulfone
And metal foil such as aluminum foil and stainless steel foil
Can be mentioned. To achieve the object of the present invention effectively,
The surface roughness of the porous support is determined by the center line average surface roughness Ra (cutoff).
0.03 μm or less at 0.25 mm)
0.02 μm or less, more preferably 0.01 μm or less
is there. Further, these non-magnetic supports are simply provided by the center line flat.
Not only low average surface roughness but also rough bumps of 1μm or more
Preferably, it does not occur. Also the surface roughness shape is necessary
Filler size and amount added to non-magnetic support depending on
Can be freely controlled by these
An example of the filler is oxidation of Ca, Si, Ti, etc.
Products, carbonates, and fine organic resin powders such as acrylic
I can do it. Web running of non-magnetic support used in the present invention
The F-5 value in the row direction is preferably 5 to 50 kg / m
m^TwoAnd the F-5 value in the web width direction is preferably 3 to 30.
kg / mm^TwoAnd the F-5 value in the long hand direction of the web is c.
It is generally higher than the F-5 value in the eb width direction,
Especially when it is necessary to increase the strength in the width direction
Not. The web running direction and width of the support
The heat shrinkage at 100 ° C for 30 minutes is preferably 3% or less.
Below, more desirably 1.5% or less at 80 ° C. for 30 minutes.
The heat shrinkage is preferably 1% or less, more preferably 0.1%.
5% or less. Breaking strength 5 to 100k in both directions
g / mm^Two, Elastic modulus is 100 ~ 2000kg / mm^TwoBut
desirable. The organic solvent used in the present invention may have any ratio
With acetone, methyl ethyl ketone, methyl isobutyl ketone
Ton, diisobutyl ketone, cyclohexanone, isophor
Ketones such as rone, tetrahydrofuran, etc., methano-
, Ethanol, propanol, butanol, isobutyl
Ru alcohol, isopropyl alcohol, methyl cyclo
Alcohols such as hexanol, methyl acetate, acetic acid
Butyl, isobutyl acetate, isopropyl acetate, lactate
And esters such as glycol acetate, glycol dimethyl
Ether, glycol monoethyl ether, dioxa
Glycol ethers such as benzene, benzene, toluene
, Xylene, cresol, chlorobenzene, etc.
Aromatic hydrocarbons, methylene chloride, ethylene chloride
Id, carbon tetrachloride, chloroform, ethylene chlorohydrate
Chlorinated hydrocarbons such as phosphorus and dichlorobenzene, N,
Uses N-dimethylformamide, hexane, etc.
Wear. These organic solvents are not necessarily 100% pure.
Isomers, unreacted materials, by-products, decomposition
It does not matter if impurities such as substances, oxides, and moisture are included.
No. These impurities are preferably 30% or less, more preferably 30% or less.
Preferably it is 10% or less. The organic solvent used in the present invention is
If necessary, the type and amount can be changed between the magnetic layer and the intermediate layer.
I don't know. , Using a highly volatile solvent for the first layer
In the first layer, a solvent with a high surface tension (cyclo
Xanone, dioxane, etc.) to increase application stability
Using a solvent with high solubility parameters for the second layer
Raise the number, for example.
Of course it is not limited. The magnetic recording medium of the present invention is characterized in that the ferromagnetic powder
With the binder resin and, if necessary, other additives
Kneading and dispersing using a solvent, and applying a magnetic paint on the non-magnetic support.
Cloth, orientation and drying if necessary. The magnetic paint of the magnetic recording medium of the present invention is produced.
The kneading step, the dispersing step, and the
The mixing process, which is provided as necessary before and after these processes,
You. Even if each process is divided into two or more stages
I don't care. Magnetic substance, binder and carbohydrate used in the present invention
Black, abrasives, antistatic agents, lubricants, solvents, etc.
Which ingredients can be added at the beginning or during any process?
I don't know. In addition, each raw material is divided into two or more processes
May be added. For example, kneading polyurethane
Process, dispersion process, mixing process for viscosity adjustment after dispersion
You may put it separately. In kneading and dispersing the magnetic paint, various mixing
A kneader is used. For example, two-roll mill, three-row mill
Le mill, ball mill, pebble mill, tron mill, sand
Grinder, Szegvari, Atlas
Iter, high speed impeller disperser, high speed stone mill, high
High-speed impact mill, disperser, kneader, high-speed mixer,
You can use a homogenizer, ultrasonic disperser, etc.
You. In order to achieve the object of the present invention, a conventional
It is possible to use a known manufacturing technology as a part of the process.
Needless to say, continuous kneading is required in the kneading process.
Use something with strong kneading power, such as pressure kneader
To obtain a high Br of the magnetic recording medium of the present invention for the first time.
Can be. When using continuous kneader or pressure kneader
Is all or part of the magnetic substance and binder (but not all
30% or more of the mixture is preferable) and 100 weight of magnetic material
Parts are kneaded in the range of 15 to 500 parts by weight.
You. The details of these kneading processes are described in
No. 6338, JP-A-64-79274
Have been. In the present invention, JP-A-62-212933 discloses
By using the simultaneous multi-layer coating method as shown
It can be produced more efficiently. The magnetic recording medium of the present invention contains
Residual solvent is preferably 100 mg / m^TwoBelow, further
Preferably 10 mg / m^TwoThe following is included in the magnetic layer
Less residual solvent than the residual solvent contained in the nonmagnetic layer.
Is preferred. The porosity of the magnetic layer is lower for the lower layer and the uppermost layer.
Preferably 30% by volume or less, more preferably 10% by volume
% Or less. The porosity of the non-magnetic layer is greater than the porosity of the magnetic layer
Larger is preferable, but the porosity of the nonmagnetic layer is 5% by volume or less.
If it is above, it can be small. The magnetic recording medium of the present invention has a lower layer and an uppermost layer.
However, depending on the purpose, the lower layer and the uppermost layer
What can be changed is easily estimated.
For example, increasing the elastic modulus of the top layer to improve running durability
At the same time, the lower layer has a lower elastic modulus than the magnetic layer
For example, the contact of the medium with the head is improved. [0082] By such a method, the
Magnetic layer orients the ferromagnetic powder in the layer if necessary
After the treatment, the formed magnetic layer is dried. Also necessary
By surface smoothing or cutting to the desired shape
As a result, the magnetic recording medium of the present invention is manufactured. More than
Disperse composition for upper layer and composition for lower layer with solvent
Then, the obtained coating solution is coated on a non-magnetic support and oriented.
After drying, a magnetic recording medium is obtained. The elastic modulus at 0.5% elongation of the magnetic layer is
Desirably 100 to 2000 in both application direction and width direction
kg / mm^TwoThe breaking strength is desirably 1 to 30 kg /
cm^TwoThe elastic modulus of the magnetic recording medium depends on the web application direction and width.
Preferably in the direction of 100 to 1500 kg / mm^Two, The rest
The run is preferably 0.5% or less and 100 ° C or less.
The heat shrinkage at any temperature is desirably 1% or less,
Preferably 0.5% or less, most preferably 0.1%
It is as follows. The magnetic recording medium of the present invention can be used for video,
Even for tapes such as audio
It may be a floppy disk or a magnetic disk,
Signal loss due to dropout is fatal
This is especially effective for digital recording media.
Further, the lower layer is a nonmagnetic layer, and the thickness of the uppermost layer is 1 μm or less.
With high electromagnetic conversion characteristics, high density and large capacity
An amount of magnetic recording medium can be obtained. [0085] EXAMPLES Examples of the present invention are described below in comparison with comparative examples.
This will be described specifically. Example 1 Nucleation 2M FeCl in a sealable 1 liter glass container_Three water
200 ml of 5.94N NaOH aqueous solution in 200 ml of solution
Is added in 5 minutes while stirring, and further 10 minutes after the addition is completed.
While stirring, and the vessel was completely sealed. Orb preheated to 100 ° C
And kept for 48 hours. After 48 hours, quench with running water
The reaction solution was centrifuged at 18,000 rpm for 15 minutes.
Centrifuged for minutes and discarded the supernatant. Add distilled water to this
It was redispersed, centrifuged again and the supernatant was discarded. like this
The washing with water was repeated 4 times using a centrifuge. Washing with water
Of finished hematite particles (average particle diameter about 0.1 μm)
The precipitate was lyophilized. 0.5 ml for 4 g of this dry powder
Of distilled water and pulverized with a planetary mill for 30 minutes.
After washing in a beaker using 0 ml of distilled water,
The mixture was ultrasonically dispersed for 30 minutes. This dispersion was prepared for 10,000
Centrifuge at 30 rpm for 30 minutes to obtain ultrafine hematite
(Average particle size about 100 Å) is dispersed
The supernatant was taken out to obtain a nucleus crystal liquid (nuclear crystal A). Obtained
The electron micrograph of the nucleus A is shown in FIG. The nucleus
The iron concentration in the solution A was 1800 ppm. Size control of monodisperse spindle type hematite 2M / L FeCl in 1L glass beaker_Three
4.8N NaOH aqueous solution 150m in 150ml aqueous solution
is added in 5 minutes with stirring, and after the addition is completed, another 10
After stirring for 2 minutes, the obtained ferric hydroxide gel was
Take 6 samples each in a 200 ml tightly stopperable container
Was. While stirring each of the nuclei A shown in Table 1,
Each, and 5 minutes later, 0.12 M / liter of N
a_Two SO_Four 20 ml of aqueous solution is added to each and stirred for 5 minutes
Was. In an oven that has been previously heated to 100 ° C
And held for 48 or 72 hours. Hold for a predetermined time
After quenching, the reaction solution was quenched with running water, and the reaction solution was centrifuged for 1 hour.
The mixture was centrifuged at 8000 rpm for 15 minutes, and the supernatant was discarded.
Distilled water is added to this to redisperse, centrifuged again, and the supernatant is
I was sorry. Thus, washing with water using a centrifuge is performed for 3 hours.
Repeated times. Next, add 1M / liter ammonia water.
After redispersion, the mixture was centrifuged and the supernatant was discarded. Distill this
Add water, redisperse, centrifuge again and discard supernatant.
Was. Repeat the washing three times using the centrifuge in this way
did. The product was lyophilized. Grains obtained in this way
Observed with a transmission electron microscope, the average major axis length and needle ratio (length
Axis / minor axis). Table 1 shows the results. Table 1
Spindle type hematite obtained in (1-A) and (1-D)
2 (a) and 2 (b) show electron microscope photographs of
Was. Production method of ferromagnetic iron oxide Monodisperse spindle type hematite particles 5 thus obtained
g into a firing tube and air is flowed at 2 liters / minute.
While heating in an electric furnace at 500 ° C for 2 hours to perform annealing.
did. Next, while lowering the temperature of the electric furnace to 380 ° C.,
Raw gas was flowed at 2 liters / minute for 30 minutes. 380 ℃
After switching to hydrogen gas, the hydrogen gas is supplied at 2 liters / min.
Flushed and reduced for 1 hour. After reduction, switch to nitrogen gas,
The temperature of the electric furnace was reduced to 240 ° C. Next, nitrogen gas
Switch to air and let air flow at 2 liters / minute for 1 hour
Oxidized and γFe_TwoO_Three made. The obtained γFe_TwoO_Three
Is measured with a vibrating sample magnetometer (VSM-5, manufactured by Toei Kogyo).
Magnetic properties were measured at a constant magnetic field strength of 5 KOe. Like this
Observed particles with a transmission electron microscope
And the needle ratio (major axis / minor axis) were determined. Table 1 shows the results. [0089] [Table 1] Embodiment 2 Na_Two SO_Four Added in Example 1-A to investigate the effect of
Na_Two SO_Four Example 1 except that the concentration of
The same reaction was carried out under the same conditions as in A.
And then reacted as in Example 1 to form
Produce a dispersed spindle type hematite, then follow the same procedure as in Example 1.
Firing under firing conditions, γFe_TwoO_Three Got. ΓF obtained
e_TwoO_Three With a vibrating sample magnetometer (VSM-5, Toei Kogyo
The magnetic properties were measured at a measured magnetic field strength of 5 KOe. this
Observe the particles obtained in the same manner with a transmission electron microscope and average
The major axis length and needle ratio (major axis / minor axis) were determined. Table 2 shows the results
Show. [0091] [Table 2] Further, NaH_Two PO_Four Check the effect of
In Example 1-A, NaH_Two PO_Four The concentration of
The reaction was the same as in Example 1 except for the
Particles are observed and the obtained particles are observed with a transmission electron microscope.
The average major axis length and needle ratio (major axis / minor axis) were determined. result
Are shown in Table 3. [0093] [Table 3] Embodiment 3 Monodisperse spindle type hematite prepared under the conditions of Example 1-A
In order to investigate the effect of annealing on
Reduction and reoxidation were performed by changing the heat conditions. Example 1-A
Bubbling the monodisperse spindle type hematite prepared under the conditions
Ringed hydrogen gas containing water vapor at 350 ° C
Time reduction, switch to nitrogen gas and change heat treatment temperature
Annealing was performed, followed by oxidation at 240 ° C. with air. Profit
ΓFe_Two O_Three With a vibrating sample magnetometer (VSM-5 type)
  Toei Kogyo) Measure magnetic properties with a magnetic field strength of 5KOe
did. The particles obtained in this way are observed with a transmission electron microscope.
Observation was performed to determine the average major axis length and needle ratio (major axis / minor axis). Ma
The specific surface area is Cantersorb (manufactured by Cantarchrome).
It was used and dehydrated at 250 ° C. for 30 minutes and measured. The result
It is shown in Table 4. [0095] [Table 4]Embodiment 4 5 g of the magnetic iron oxide obtained in Examples 1-A, 1-C and 3-C
PVC vinegar binder (20 wt% cyclohexanone solution
Liquid 5g) and kneaded with a triturator, then the solvent (toluene and
15 g of a 1: 1 mixed solvent of cyclohexanone is added and dispersed.
The dispersion was applied to PET with an applicator and
The magnetic field was oriented by the opposing magnet of e. The obtained sheet sample
The magnetic properties of the sample were measured using a vibrating sample magnetometer (VSM-5
The magnetic properties were measured at a measured magnetic field strength of 2 KOe. Profit
Table 5 shows the results. Comparative Examples 7 and 8 Magnetic iron oxide obtained in Comparative Example 3, Magnetic iron oxide M manufactured by Toda Kogyo
X450 (Hc 3500e, σs 72.5 emu /
g, average major axis length 0.5 μm, acicular ratio 10, specific surface area 20
m^Two / G) to form a magnetic sheet in the same manner as in Example 4.
It was created and its magnetic properties were measured. Table 5 shows the obtained results.
You. [0098] [Table 5] Embodiment 5 The monodisperse spindle type hematite obtained in Example 1-A was
And disperse cobalt sulfate and nickel sulfate in hematite.
Is 100 atomic%, Co is 6 atomic%, and Ni is 3 atomic%.
Add to the suspension so that it will be at.
Was. While monitoring the pH of this suspension,
Monia water was added to adjust the pH to 8.0, and C was added to the hematite surface.
An o, Ni compound was deposited. Centrifuge suspension and supernatant
After removing the liquid, distilled water was added and suspended again. A
Aqueous solution of sodium luminate and sodium silicate
100% by atom of Fe in aluminum, 3% by atom of Al, S
i was added to the suspension so that it became 1 atomic%, and p
While monitoring H, carbon dioxide gas was bubbled into the suspension to adjust the pH.
7.0, Al and Si compounds deposited on hematite surface
I let you. The suspension is centrifuged, and the supernatant is discarded.
Washing was repeated three times by adding water and resuspending.
Dried. The surface-treated monodisperse spindle type hematite was
Spread 5 g thinly in a firing tube, and under various conditions shown in the table,
Processing under the same conditions. Annealing in hematite removes nitrogen
Heat at a prescribed temperature for 2 hours in an electric furnace while flowing at 2 liters / minute.
Heated. Next, after the temperature of the electric furnace reached 450 ° C., hydrogen
Switch to gas and flow hydrogen gas at 2 liters / minute and return for 6 hours
I got it. Surface treatment when annealing with magnetite
Bubbling of hematite in water
Reduced with hydrogen gas at 350 ° C for 1 hour, cut into nitrogen gas
Annealing at a different heating temperature
Set the temperature to 450 ° C, switch to hydrogen gas,
The mixture was reduced at a flow rate of liter / minute for 6 hours. After reduction is complete,
And cooled to room temperature. Using a gas mixer
Oxygen-containing gas is mixed with raw gas to reduce the oxygen concentration in nitrogen.
0.1% by volume and contact for 5 hours, then on metal powder
Oxygen while monitoring the temperature of the part so that it does not exceed 50 ° C
Increasing the concentration, increasing the oxygen concentration to 21%
Was performed. The obtained metal powder is transferred to a vibrating sample magnetometer (V
(SM-5 type manufactured by Toei Kogyo)
Air characteristics were measured. In addition, the specific surface area
Dechrome at 250 ° C for 30 minutes.
And measured. The obtained particles are further analyzed by transmission electron microscopy.
And the average major axis length and needle ratio (major axis / minor axis) were determined.
Table 6 shows the obtained results. [0101] [Table 6] Embodiment 6 Hematite nucleation In a sealable 2 liter glass container, 2M /
Liters of FeCl_Three 5.94NNaOH aqueous solution 500m in 500ml aqueous solution
is added in 5 minutes with stirring, and after the addition is completed, another 20
After stirring for a minute, the container was completely sealed. 100 ℃ in advance
Was placed in a heated oven and kept for 48 hours. 48 o'clock
After a while, the reaction solution is quenched with running water, and the reaction solution is separated and centrifuged.
And centrifuged at 15000 rpm for 15 minutes, and the supernatant was discarded. to this
Re-disperse by adding distilled water, centrifuge again and remove the supernatant.
I was. In this way, using a centrifuge, wash four times
I returned. Hematite particles that have been washed with water (average particle size
The precipitate (0.1 μm) was filtered and dried. This dry powder 5
Add 5 ml of distilled water to 0 g and pulverize for 30 minutes with a raikai machine.
Crushed, washed in a beaker using 500 ml of distilled water and distilled.
After adding 700 ml of water, ultrasonically disperse for another 30 minutes.
Was. This dispersion was collected and centrifuged at 10,000 rpm for 30 minutes.
And ultrafine hematite (average particle size of about 100
The supernatant liquid in which
Was. The iron concentration in the nucleus liquid was 2000 ppm. Size control of monodisperse spindle type hematite 2M / liter FeCl in 5 liter stainless beaker
_Three While stirring 1500 ml of 4.8 N NaOH aqueous solution in 1500 ml of aqueous solution,
And then stirred for another 30 minutes after the addition was complete.
Then, the obtained ferric hydroxide gel was mixed with 2000 ml of each 1000 ml.
Removed to a sealable container. The following amounts of nuclei
Add the solution with stirring and add 0.12
M Na_TwoSO_Four500 ml of aqueous solution was added to each and stirred for 10 minutes.
Place in an oven preheated to 100 ° C for 72 hours
For a while. After holding for a predetermined time, it was quenched with running water.
The reaction solution was filtered, added with distilled water, redispersed, and re-dispersed.
Filtered. In this manner, filtration, redispersion and washing with water are repeated three times.
I returned. Next, add 1M / liter of ammonia water and re-
The dispersion was heated to 80 ° C., held for 1 hour, and cooled. Filter
After adding distilled water, redispersion was repeated three times. The resulting generation
The material was dried. The particles obtained in this manner are converted to transmission electron
Observe with a microscope and find the average major axis length and needle ratio (major axis / minor axis).
I did. Table 6 shows the results. Synthesis of ferromagnetic metal powder (metal powder) The obtained monodisperse spindle type hematite (6-A, 6-B, 6
-C) so that the concentration of hematite in distilled water is 2%
Disperse and convert cobalt sulfate and nickel sulfate into hematite
Fe is 100 atomic%, Co is 6 atomic%, Ni is 3 atomic%.
%, And sufficiently stirred and mixed. This suspension
Add ammonia water to suspension while monitoring pH
The pH was adjusted to 8.0 and Co and Ni compounds were added to the hematite surface.
Was adhered. Sodium aluminate and sodium silicate
An aqueous solution of thorium contains 100 atomic% of Fe in hematite.
And suspended so that Al becomes 3 atomic% and Si becomes 1 atomic%.
To the suspension and monitor the pH of the suspension
The pH is adjusted to 7.0 by ventilating carbon dioxide gas, and the spindle is coated with Co-Ni.
Al and Si compounds were deposited on the type hematite surface.
The suspension was filtered and washed with distilled water to remove impurities. Get
Surface-treated spindle-type hematite through a molded plate with a diameter of 3 mm.
The mixture was passed, molded into a cylindrical shape, and dried. The surface-treated monodisperse spindle type hematite was
Put 500 g in a rotary reduction furnace, and in nitrogen at 500 ° C for 2 hours.
Neal treated. Next, raise the temperature to 450 ° C,
The hydrogen gas was switched at a flow rate of 20 l / min and reduced for 10 hours.
After completion of the reduction, the atmosphere was switched to nitrogen gas and cooled to room temperature. Moth
Mix the oxygen-containing gas in the nitrogen gas using a gas mixer,
The oxygen concentration in nitrogen is set to 0.1% by volume and contacted for 5 hours,
Then monitor the temperature above the metal powder and exceed 50 ° C
And increase the oxygen concentration to 21%.
Slow oxidation of the metal powder was performed. The obtained metal powder
Measured with a vibrating sample magnetometer (VSM-5, manufactured by Toei Kogyo)
Magnetic properties were measured at a magnetic field strength of 10 KOe. Also specific surface
Use Cantersorb (manufactured by Cantarchrome) for the product,
The sample was dehydrated at 250 ° C. for 30 minutes and measured. Further obtained particles
Is observed with a transmission electron microscope, and the average long axis length and the needle ratio (long axis
/ Minor axis). Table 7 shows the results. [0106] [Table 7] Preparation of coating liquid Goetite via ferromagnetic powder and iron carbonate as raw material
Commercially available Co-Ni-containing metal powder (Hc1640O
e, σs 126 emu / g, major axis length 0.13 μm, needle ratio 1
0, specific surface area 58m^Two / G) with the magnetic paint under the following conditions:
did. (Composition for upper layer)     100 parts of ferromagnetic powder     Binder resin       Vinyl chloride copolymer 12 parts           (-SO^Three 1 × 10 Na groups^-Foureq / g content             Degree of polymerization 300       3 parts of polyester polyurethane resin           (Neopentyl glycol / caprolactone polyol / MD           I = 0.9 / 2.6 / 1           -SO^Three Na group 1 × 10^-Foureq / g)     α-alumina (average particle size 0.1 μm) 1.5 parts     0.5 parts of carbon black (average particle size 100 nm)     Butyl stearate 1 part     2.5 parts of stearic acid       200 parts mixed solvent of methyl ethyl ketone and cyclohexanone 1: 1 [0108] (Composition for lower layer)     Acicular α-Fe^Two O_Three                                         80 copies         (Average particle length 0.15 μm, average needle ratio 12, Al-Si treatment         55m surface area by BET method^Two / G pH 6.4)     20 parts of carbon black         (Average primary particle diameter 16 nm,           DBP and oil amount 80ml / 100g           Specific surface area by BET method 55m^Two / G           pH 6.4)     Binder resin         Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 10 parts           (-N (CH3))³⁺Cl^-5 × 10^-6eq / g content       Monomer composition ratio 86: 13: 1 Degree of polymerization 400)         Polyester polyurethane resin 8 parts                 (Basic skeleton: 1,4-BD / phthalic acid / HMDI                 Molecular weight: 10200                 Hydroxyl group: 0.23 × 10^-3eq / g content                 -SO_ThreeNa group: 1 × 10^-Foureq / g content     Butyl stearate 1 part     2.5 parts of stearic acid     200 parts mixed solvent of methyl ethyl ketone and cyclohexanone 1: 1 Lower layer composition) Acicular α-Fe of composition for lower layer_Two O_Three Needle-like C instead of
o modified iron oxide (specific surface area 45m^Two / G, Hc850O
e, axial length 0.15 μm, axial ratio 8, Al-Si surface treatment
The same conditions were used except for the use of Above composition for lower layer
And the upper layer composition were kneaded with a kneader
Thereafter, the mixture was dispersed using a sand grinder. Got
The polyisocyanate in the dispersion is 5 parts in the lower coating solution,
Add 6 parts to the upper layer coating solution and add methyl ethyl ketone.
20 parts by weight of a 1: 1 mixed solvent of cyclohexane and cyclohexanone,
Filtration using a filter having an average pore size of 1 μm
And adjust the coating liquid for non-magnetic layer formation and magnetic layer formation.
did. The thickness of the obtained lower layer coating solution after drying is
Coating to 2μm, immediately after that for lower layer coating
While the layer is still wet, the thickness of the magnetic layer
To a predetermined thickness so that the polyethylene
Wet simultaneous multi-layer coating on phthalate support and orientation
If processing is to be performed while both layers are still wet
-Co magnet (3000 gauss of surface magnetic flux) and solenoid
Magnet of ferromagnetic powder by magnet (surface flux 1500 Gauss)
In-situ orientation was performed and dried. Then composed of metal rolls
Roll temperature is set to 90 ° C with a 7-stage calender
To obtain a web-like magnetic recording medium,
It is slit to 8mm width and 8mm video tape
The magnetic properties of the sample were made by Toei Kogyo's vibrating sample magnet.
Using a force meter VSM-5, measure with an applied magnetic field of 5 kOe.
Was. The lower layer uses magnetic iron oxide with a lower Hc than metal.
Is SF for Hc corresponding to metal and high Hc part
D was calculated. 8 mm video camera manufactured by Fuji Photo Film Co., Ltd.
5MHz and 10MHz signals using FUJIX8
And the playback output when these signals are played back is
It was read from a scope and measured. Output is a commercially available meta
The value was expressed as a relative value with respect to a single-layer tape using powdered aluminum. Measurement
The results are shown in Table 8 below. [0112] [Table 8][0113] EFFECT OF THE INVENTION A monodisperse spindle type hemata is produced by a conventional hydrolysis method.
Monodispersed even at a concentration 10 to 100 times the concentration at which the site was obtained
Spindle type hematite can be obtained, making it an economical manufacturing method
Was. In addition, the weight-proof hematite of the present invention is converted to magnetic iron oxide.
When performing annealing, the magnetic properties
(In particular, Hc) could be increased. G also obtained
The ferromagnetic iron oxide using the ferromagnetic iron oxide is SQ and SF
D (Measurement of Hc distribution in derivative curve of BH curve)
Compared to the magnetic iron oxide manufactured by the conventional goethite method
Is excellent. The monodisperse spindle type hematite of the present invention is
Ferromagnetic metal powder obtained as raw material together with binder resin
The magnetic recording medium dispersed and coated on a non-magnetic support is square
Magnetization using conventional ferromagnetic metal powder with ratio and SFD
It shows much better properties than recording media. In particular, non-
A thin magnetic layer (especially ferromagnetic metal powder)
Remarkable improvement in short-wavelength output of magnetic recording medium with layer
It is. As is clear from the above results,
Metal powder (ferromagnetic metal powder) synthesized from dispersed hematite
C), the particle size is large and 1 /
When the frequency is 2 or more, the output near the frequency becomes
It can be seen that it is lower than that of the above.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an electron micrograph of the particle structure of fine hematite (nuclear crystal A) particles used as a nucleus crystal prepared in Example 1, FIG. 2 is (a) (B) is an electron micrograph of the particle structure of the monodisperse spindle type hematite particles obtained using (1-A) and (1-D) of Example 1, respectively.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C01G 49/06 C01G 49/02

Claims (1)

(57) Patent Claims 1. A dispersion of the sulfate ion (S0 ₄ ^2-) or hematite particles to gel a suspension of ferric hydroxide in the presence of phosphate root ions as seed crystals After that, the second
A method for producing monodisperse spindle type hematite particles for hydrolyzing iron, wherein the concentration of sulfate ions in the gel suspension of ferric hydroxide is 0.01 mol / L to 0.1 mol / L.
Mol / l or the concentration of phosphate ion is 0.001 to 0.01 mol / l, and the particle diameter of the hematite fine particles used as the nucleus crystal is 30 to 20.
A method for producing monodisperse spindle type hematite particles, wherein the particle diameter is 0 Å.