JPS6188505A - Manufacture of ferro magnetic iron powder - Google Patents

Abstract

PURPOSE:To effectively obtain ultra-fine iron system ferro magnetic acicular metal powder by introducing Mn and Co for coprecipitation in order to form fine particles of acicular iron oxyhydroxide and including BZn in order to keep acicularity of fine particles as the raw material. CONSTITUTION:A water soluble Mn and Co compound are added in the specified amount into the aqueous solution of ferrous sulfate, iron hydromonoxide hydrogel is formed by neutral reaction with excessive KOH and fine particle of acicular iron oxyhydroxide can be formed through oxidation and crystallization while the air is being introduced. For introduction of Mn and Co, the water soluble sulfate is used and selection is carried out so that Mn/Fe=0.1-10%, Co/Fe=0.1-10% in the atom weight % for Fe. Simultaneous addition of Co to the Mn provides both acicularity and heat resistance characteristics. After washing by water, when the surface is subjected to the deposited denaturation processing with the particle holding elements mixed and dispersed into the water with content of B and Fe of B/Fe=0.05-5% in the atom weight % including the insoluble boric zinc, crystals are well combined without enlargement of crystals. Thereafter, stabilized ferro magnetic iron powder can be obtained by adding, as required, the drying or other processes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing ferromagnetic metal-like fine particles as a magnetic material in a magnetic recording medium suitable for high-density recording.

[Prior art]

Regarding magnetic materials for magnetic recording, in order to measure high output and low noise in a wide recording wavelength range, we use highly uniform fine 1 (11-shaped) particles with high coercive force (HC). a sum 11
Basically, a custom-made magnetic is required that has both large hydrogenation (σS) and residual magnetization (σr), and a squareness ratio (its-σ "/σS) as large as possible. In recent years, high-density recording is socially required,
Due to its excellent magnetic properties, ferromagnetic metal powder was first used as a material for audio tape, and in the near future it is expected to be used as a material for video.

In the case of iron-based ferromagnetic metal powder, it is necessary to give it a fine acicular particle shape, and the manufacturing method suitable for mass production is hydroxylation through a neutralization reaction with ferrous salt and excess alkali. Ferrous hydrogel is formed, then oxidation and crystallization are carried out while introducing air to synthesize fine acicular iron/hydroxide particles, and these fine particles are reduced with hydrogen, etc. while maintaining their shape. A method of subjecting iron particles to reaction to produce iron fine particles rich in shape anisotropy is known and has been put to practical use. However, iron particles are generally easily sintered, and in the hydrogen reduction reaction, which usually requires temperatures of 350°C to 400°C or higher, the acicular nature of the raw particles cannot be maintained, and appropriate magnetic It is difficult to form iron fine particles with a

In order to avoid this, a technique has been developed in which particle shape maintaining components, mainly Sl and AI, are applied to the surface layer of the acicular iron hydroxide fine particles (for example, JP-A-52-1
34858).

[Problem to be solved by the invention]

By introducing shape-retaining components such as Sl and A1, the shape of the reduced iron particles can be significantly improved, making it possible to fully satisfy the magnetic spacing required for ferromagnetic metal powder for magnetic recording. However, due to the extremely porous particle shape, when processed into magnetic recording media, the media lifespan is not long enough to guarantee the reliability of the media. development was desired.

Furthermore, in order to achieve higher density recording, improve noise, or produce high-performance magnetic powder for video use, iron-based particles with finer particle shapes are produced and put into practical use. Therefore, there was a need for improved magnetic powders that were custom made to oxidize against air.

Examples of improving the lifetime of magnetic media and the activity of fine ferromagnetic iron-based metal powders from the standpoint of particle morphology design include:
)/- Since the method is to develop a porous particle shape, bonding between unit particles (also called crystallites, daleins, crystallinotes, etc.) that make acicular iron fine particles is possible. There are ways to advance this as much as possible.

In the manufacturing process of ferromagnetic iron powder mentioned above, setting the calcination temperature or reduction temperature as high as possible is the simplest and most effective method, but in this case, at the same time, Since the above-mentioned crystallites become enlarged to one umbrella end, this causes deterioration of the electromagnetic conversion characteristics that the magnetic medium should originally have, especially noise and output in a high frequency band, which is not preferable. First, in the step of depositing a particle shape-retaining component onto the surface layer of the acicular oxyhydroxide Hosei particles described above, the present inventors used fiber-poured zinc borate as one of the deposited components. By doing so, the heating temperature in the hydrogen reduction reaction can be lowered = j
From S, it is possible to promote as much cooperation as possible between crystallites without making any effort to enlarge the crystallites that were transported earlier, and therefore, it is possible to proceed with the cooperation of the crystallites as much as possible. Even if there is a change in the conversion characteristics, the noise can be improved and the media lifespan can be improved without any problem (load μ:
11861-48612).

Thus, the ferromagnetic (ferromagnetic) raw iron metal powder used as a magnetic material for magnetic recording has characteristics such as acicular fine particle nature, magnetic properties, pigment customization,
Improving handling stability and media life We have now established a manufacturing method that greatly exceeds the conventional technology for both of the following advantages. However, after that, we researched the production of finer acicular ferromagnetic iron-based metal powder with the aim of further improving output in the noise and high frequency bands and producing metal magnetic powder suitable for shattered video applications. However, as the grain size becomes ultra-fine, the saturation magnetization, which is the σS value mentioned earlier, inevitably decreases, and the basic (1B magnetic properties) required for magnetic materials for magnetic recording are reduced. Finding out the things that cannot be satisfied and trying to solve these problems is important because of the advent of magnetic recording media, which is more financially worrisome. It had become.

[Purpose of L Immunization] The present invention aims to further improve noise and output in a high frequency band in a magnetic recording medium, and furthermore, to provide a metal magnetic 15J suitable for video use. When planning industrial production of ultra-fine acicular ferromagnetic iron metal powder, it is important to consider the characteristics of sword-shaped Mi particles, magnetic customization, pigment specialization, handling stability, and the ability to improve media life. The purpose is to provide a manufacturing method that greatly improves the conventional technology.
It is something.

[Basic idea of the invention]

In order to solve the above-mentioned problems, the present inventors have made various studies and found that when synthesizing acicular iron oxyhydroxide fine particles, Mn and Co components are coprecipitated. Next, we discovered that it is extremely effective to include zinc borate as a component that maintains the acicular nature of the fine particles used as the raw material, and we have arrived at the present invention.

[Disclosure of the invention]

In the present invention, one of the requirements is to introduce CO in a co-precipitation manner.

Conventionally, the inclusion of a CO component in magnetic powder for magnetic recording has been frequently used mainly for the purpose of improving its magnetic properties, especially increasing its HC value, and has been put into practical use.
For example, Akashi Okabe = "Advances in magnetic tape."

For Japan 1 core! Journal of the Japanese Society of Ki, 7-7. %(3),
185 (1985)]. However, in this case,
It is based on the fracture modification of cobalt/ferrite phase on the surface of acicular ganomeric iron oxide ribbed particles, and moreover, these cobalt/ferra/f-type gamma-iron oxide fine particles can be directly used as magnetic powder for magnetic recording. 1, and has no technical relevance to the present invention. In the relatively early stages of research into ferromagnetic metal powders for magnetic recording, the study was mainly motivated by analogy with alloy-based permanent magnet materials. Evaluation of 'l' as a powder was underway. For example, Toshiaki Izumi et al. = [Custom order of iron-cobalt alloy powder] [IEICE/Magnetic Recording Research Group materials,
According to MR78-9 (1978), Fe-Co
Particle shape/particle size/crystallinity/magnetic customization of system alloy fine particles/I1y as audio tape, customization of magnetic conversion characteristics conversion progressed, 70%Fe-30%C.

Although it has been shown that the doubling yarn is superior, it has been shown that the remarkable improvement in properties cannot be obtained by introducing a trace or small amount of Co component as in the present invention9. It is clear that the systems are different. In addition, in Japanese Patent Publication No. 56-39682, a method for producing ferromagnetic metal iron powder for magnetic recording containing trace to small amounts of Co is described. It is stated that a metal alloy powder with excellent custom properties can be obtained by adhering and adsorbing Zn or (and) Or or a compound of Zn and Cu to a doped metal. However, since the action and role of the CO-component is not described, and there are no working examples, it is not necessarily easy to compare and verify with the present invention, but considering the gist of the invention, Effect/role of particle shape retention (' is exclusively Z
It is clear that this is an effect of adhesion/adsorption treatment using a compound of n or (and) cr or Zn and Cu, and is not an effect of utilizing the special action/role of the CO component. It can be said that the technical systems are different. Further, in JP-A-58-44701, a method for producing a cobalt-containing hazardous magnetic powder is described, but the main purpose of the invention is to obtain a heat-resistant effect by adsorbing molybdenum, and The specific action of the ingredients was not invented, and it can be said that the technical system is different from the present invention.

The Mn and Co components used in the present invention may be water-soluble sulfates, nitrates, chlorides, or various mineral acid salts, and may be used alone or in combination of two or more, but sulfates and nitrates may be used. Although this is most often used, this does not represent a limit to the applicability of the present invention.

The amounts of these Mn and Co components introduced are ~! in atomic weight ratio with Fe! n, /'Fe = 0.1/IDO~
1 o/100 and Co711”c, = 0.1/
100-1 o/i 00, preferably Mn/Fe=
o, 2/100 to 5/100 and Cuc = i/io
A range of o to S/100 is appropriate. When the introduced iIk of Mn and Co components is less than the above-mentioned ・1・suction pressure, the effect of these four subcomponents is not noticeable, and the hole G・, ;1 attack, H: exceeds the above range. The synthesis of acicular iron oxyhydroxide 1++ becomes j'''Lli:-''ku・suku,
In many cases, hydrated Maguitite spherical particles or green
It has a strong tendency to remain in the formation of last particles, and cannot be said to be preferable as raw material particles for iron-based magnetic materials for magnetic recording. Although the mechanism of action of 1411 and Co components is not necessarily clear, for NJn 5X, it is a function to improve the surface heat characteristics in the hydrogen reduction reaction process of fine acicular iron oxyhydroxide particles. The present inventors have discovered that Co.
It is judged that when used in combination with other components, a revolutionary synergistic effect of rich acicularity and heat resistance properties can be imparted to the fine iron oxyhydroxide particles. That is, generally speaking, the introduction of the N+11-component tends to have the effect of lowering the axial ratio of the formed oxyhydroxide [arsenic fine particles], but as will be described later, the Co- By adding it simultaneously with other components, it has become possible to achieve both needle νζ properties and heat resistance. Conventionally, in the formation of arsenic oxyhydroxide fine particles, the introduction of a Co component has not always been carried out, but for example, as described in JP-A-58-48408, fine particles have been introduced. It is a mistake to acknowledge the effects of
The remarkable acicularity is thought to be due to a synergistic effect with the 1.4n-component, and can be said to be a fact discovered for the first time by the present inventors.

), In and Co components can be introduced using ferrous salt and! A ferrous hydroxide hydrogel is formed by the neutralization reaction of lil with an alkali, and then fine acicular iron oxyhydroxide particles are synthesized through oxidation and crystallization while introducing air. In a known synthesis process using a so-called wet neutralization/oxidation reaction, a method is adopted in which a predetermined amount of the water-soluble nMn and Co compounds described above are added to an aqueous ferrous salt solution and introduced by a coprecipitation method using an alkaline material. Bye. In addition, the ferrous salt used in the present invention is a sulfate, chloride, or various mineral acid salts, and can be used alone or in combination of two or more, but sulfate and Jα are also often used. However, this does not indicate a limit to the application of the present invention. Furthermore, the alkaline materials used in the present invention include water (hyalkali) such as KOH and NaOH, carbonate alkali such as K2CO3, Na, and Co3, NH3-aqueous solution, and even urea in a water bath state. There are substances that undergo thermal decomposition upon heating and have substantially the same effect as pli (3, etc.), and the selection of these substances is not necessarily an essential element in carrying out the present invention.

In the wet neutralization/oxidation reaction, the type, amount, and aqueous solution concentration of the iron salt, the type and amount of the water-soluble Mn and Co compounds mentioned above, the type, amount, and aqueous solution concentration of the alkaline material, and the neutralization There are many operational factors in the reaction stage, such as the planting rate and maintenance time, the temperature and air supply amount, speed, and time for proceeding with the acid/arc reaction, and all of these factors affect the fineness of the final product. Acicular hydroxide f gives a subtle shadow g to the morphology of arsenic particles.

In this reaction system, the effects caused by introducing ~1n and Co components are generally complex and wide-ranging, but to put it one step further, Mn and Co components are introduced into 4'1. In comparison with the case where no
Set it 10℃ higher, and in some cases use air! ＃Salary amount 6
If the amount is increased by a factor of 0 to 50, the specific surface area will be almost the same, but the axial ratio will be thicker. The shape and state of iron particles may be affected.

Next, the iron oxyhydroxide fine particles are thoroughly washed with water to remove excess alkali and unnecessary subcomponents, and then subjected to a modification treatment to adhere to the particle surface with a particle shape-retaining component containing sparingly soluble zinc borate. receive. The present inventors were the first to disclose that sparingly soluble zinc borate has a very specific particle shape retention effect (Japanese Patent Laid-Open No. 58-48612).
When applied to the needle-like iron oxyhydroxide fine particles containing the Mn and Co components described above, the crystallites do not enlarge as described above, and at the same time, the bonding between the crystallites is achieved by conventional methods (e.g. They discovered that there is a synergistic effect that allows you to progress to the point where you will never see it again.

The fracture modification treatment using a particle shape-retaining component containing poorly soluble subboric acid 8) of the cylindrical iron hydroxide fine particles is as follows:
It can be carried out using a mixer such as a mixer, a roll mixer, a stirrer] (: a mixer or a ball mill).Furthermore, it is convenient to mix and disperse. :teeth,
One volume of zinc borate dissolved in water is 01 ~ [,
Since it is small, smaller than candy, water can be used as a dispersion medium. For the medium outside the water mass, boric acid “
■ Does not dissolve lead, or even if it does, the solubility is 1w,
Any medium having extremely low solubility less than z may be used as a dispersion medium. This is because the dispersion medium is separated from the zinc borate by filtration or transpiration, but if the solubility is high, the zinc borate migrates to the filtrate together with the dispersion medium during filtration), or for example, This is because, as shown in No. 42832, non-uniformity occurs in the concentration distribution of zinc borate during transpiration.

The amount of zinc borate introduced is B/ in terms of atomic weight ratio with iron.
we = o, os / 1oo ~ s / 1oo
% is preferably in the range of 0.2/100 to 2/100. Even if it falls within this range, the magnetic properties will deteriorate.

The acicular arsenic oxyhydroxide particles were subjected to an adhesion modification treatment using a particle shape-retaining component containing poorly soluble zinc borate.
Thereafter, dry under an air bath at 100 to 150°C.
Day 1 - Pulverize or granulate as necessary to obtain dry oyster/iron hydroxide fine particle powder. In some cases, two more
Calcination treatment may be performed at 50 to 450°C to produce calcined iron oxyhydroxide fine particles.

The production of ferromagnetic metallic iron (α-Fe) fine particles using this dried or calcined iron hydroxide fine particle powder as a raw material can be carried out generally according to known methods6. A steel pipe reactor equipped with a gas preheater and whose temperature can be regulated from the outside is filled with the above-mentioned dry, air- or calcined iron oxyhydroxide fine particle powder and kept at 2.300-500°C.
If a reducing gas, mainly N2-gas, is introduced and brought into contact with an appropriate amount of water depending on the case, it will first become magnetite particle powder, and then the reduction should be continued while paying attention to the moisture content. It is possible to obtain ferromagnetic gold and metal iron fine particles.

This contact)! The photoreaction may be carried out in either a fixed bed or a moving bed, and may be carried out at normal pressure or under pressure. There is no basic tljlJ limit for the supply amount and speed of raw material scraps for reaction, but if expressed in terms of gas hourly space velocity (GH8V),
A range of 0.1 to 100 Nt/gr-Fe/hr, preferably 5 to 50 NU'gr-Fe/hr is suitable. If the amount is less than this range, the reaction progresses slowly and is not practical, and if the amount exceeds this range, the pressure drop within the reaction system will only increase, so it cannot be said to be necessarily suitable for reaction operation.

Furthermore, if the temperature range deviates from the expected range, the reaction progresses at low temperatures and takes a long time to complete, making it unrealistic, while at high temperatures, the reaction speed is too fast and may cause unnecessary particle damage.・This is not a good idea as it tends to lead to destruction and even sintering.

When the above reduction reaction is completed, the circulating gas components are replaced with N2
- Switch to an inert gas component such as gas, and increase the heating temperature to 20℃.
The temperature is lowered to 0° C. or below, and then, in order to help suppress the oxidation activity, the surface of the particles of the reduced product is gradually oxidized while introducing an appropriate amount of an oxidizing agent containing water vapor or molecular oxygen.

According to the method of the present invention, acicular arsenic oxyhydroxide fine particles into which Mn and CO components have been co-precipitated are used as a raw material, and the particle shape containing zinc borate]-r component is subjected to γr modification treatment. After that, when stabilized ferromagnetic iron powder is produced by calcination, reduction, and slow oxidation, it is inherited as a high-magnification electronic title.
Phenomena such as particle breakage/destruction and interparticle cross-linking, i.e., sintering, are hardly observed. It is recognized that the crystallites have a sufficient size to express a custom-made structure, and that the bonding between the crystallites has progressed sufficiently.Furthermore, its magnetic properties are similar to Hc if it is a system for audio use. ~1
250-13000e, os ~140-155em
U/gr, also Hideo's matchmaking, HC ~ 145
0~15500e, σS~125~135■u/gr1
It has a special order in which it is ammonia-hydrated for magnetic recording.Also, since it has a non-porous particle morphology, its oxidation activity is mild. In addition, the polymerization with OH-group-containing PVC/PVC resins, which are often used in magnetic media, has been improved compared to the conventional particle shape retention component system with 6 i/p, l as the main components. In order to move forward much more strongly,
It is recognized that the lifespan of ib, itself is prolonged.

[Effect]

In the present invention, a ferrous hydroxide hydrogel is formed by a neutralization reaction between a ferrous salt and an excess alkali, and then it is subjected to acid-rhybridization and crystallization while introducing air to form fine acicular oxyhydroxide. In the method of synthesizing iron hydroxide particles and subjecting the fine particles to a reduction reaction with hydrogen or the like while maintaining their shape to obtain iron fine particles with rich shape anisotropy, the first step is to combine Mn and Co components. Introduced into precisely fine acicular iron oxyhydroxide particles,
The second major feature is that it mainly contains zinc borate as its particle shape-retaining component.

The present inventors discovered for the first time that introducing a specific amount of Mn component into acicular iron oxyhydroxide particles as a raw material for ferromagnetic iron powder for magnetic recording is even more effective (
JP-A-56-104720). Before that,
For example, as described in JP-A No. 54-64100, the 111n-component is rather an acicular oxyhydroxide (considered to be a harmful component for arsenate particles) as a raw material for ferromagnetic iron powder for magnetic recording. It was sobbing. Japanese Unexamined Patent Publication 1973-
As described in 104720, although the mechanism of action of the Mn component is not completely clear, it is believed that the mechanism of action of the Mn component is It has been found that it has a shallower F which improves heat resistance properties. Therefore, part of the role and action of the Mn-component in the present invention is that it plays a role in improving the heat resistance properties of fine acicular iron hydroxide particles during the hydrogen reduction reaction process. seems to be quite predictable.

In the present invention, a specific amount of C is added to acicular iron oxyhydroxide particles as a raw material for ferromagnetic iron powder for magnetic recording.

The action and role of introducing the component is to increase the acicularity of the formed fine particles, thereby improving the dispersibility at the paint stage and orientation at the coating stage when transitioning to a fine particle system. extremely effective. Furthermore, surprisingly, when used in combination with a specific amount of Mn component, a further increase in acicularity was observed compared to when used alone. In addition, a significant improvement in heat resistance properties during the reduction process can be observed.

1. In the present invention, a particle shape retaining component containing zinc borate is used. However, the poorly soluble zinc borate has a specific action and effect in the method for producing ferromagnetic iron powder for magnetic recording (this is not the case in this invention). It was discovered for the first time by the inventors (Japanese Patent Application Laid-Open No. 58-48612). Being poorly soluble is essential for uniform adhesion and modification treatment to the surface of raw iron oxyhydroxide fine particles. Zinc borate and zinc borate serve as chemical 1'13 decoration agents to develop a dense particle morphology.The transition to a fine particle system inevitably leads to a decrease in heat resistance, and A till reduction reaction was essentially desired, and this became possible only with the use of pre-lead borate.

As described above, in the present invention, a ferrous hydroxide hydrogel is formed by a neutralization reaction between a ferrous salt and an excess alkali, and then fine particles are formed through oxidation and crystallization while introducing air. In the method of synthesizing jr-like iron water rν ratio iron particles, and subjecting the fine particles to a reduction reaction with hydrogen or the like while maintaining their shape, they are made into particles rich in shape anisotropes. Firstly, Mn and Co-O components are co-precipitated into fine ζ′Iυ acicular iron oxyhydroxide particles, and secondly, zinc borate is mainly used as the particle shape-retaining component. This is a major feature, but in transitioning to the enemy particle system,
We have discovered that both are essential manufacturing factors, and have completed the present invention.

[Preferred Mode for Carrying Out the Invention] The present invention will be described in detail below with reference to Examples and Comparative Examples.

[Example-1] - Synthesis of iron oxyhydroxide fine particles This example shows an example of the synthesis of oxy/hydroxide [arsenic fine particles] into which Mn and CO were coprecipitated (Table 1).

In this example, a reactor with an internal volume of 1,501 mm and equipped with a stirrer and temperature regulator capable of high speed rotation, and a piping system for feeding fine air bubbles was used, but a reactor of a different type was used. Even if you use it, the essence will not change.

Experimental example-1>1i'eSO,,' 7H3O: 2.5 kgr (
: 503g as Fe) was put into 50jl of water kept at 40℃ to make an aqueous solution, then Mn5O,
5H20: 44gr (:',,10g as in
r) and CoSO4@7H20: 48gr (:C
Add 10gr as o).

This 3; in, Co-containing PC salt aqueous solution (: ゛) I
lIAρc = 2, /+00Wt, & co/
Fe = 2 / 100 Wt) was soaked in a separately prepared NaOH: 5.9 kgr f water 509, and an aqueous solution kept at 40°C (added gradually for about 1 hour without stirring. Repeat this step to complete the neutralization reaction.

Next, while maintaining the temperature of the system at 40°C, air was introduced at a feed rate of 497ml to start the oxidation/crystallization reaction, which continued for 1.5 hours to produce slightly dark yellow oxywater. Iron oxide fine particles form an insoluble precipitate.

Cool the system to room temperature, then wash with water and suction filtrate to remove the nuclei! , I
A paste of n & Co co-precipitated arsenic hydroxide particles was obtained.

A part of the paste of the M11 &Co co-precipitated iron/iron hydroxide particles was collected and dried at 110°C overnight. rin
& Qa co-precipitated oxygen/iron hydroxide particle dry powder was obtained,
When the content of Mn & Co was subjected to fluorescent X-ray analysis, Mn/11'e = 190/1 oowt
, ratio, and Co/'Fe ==1.92/100~
vt, ratio was obtained, and it was confirmed that the composition was close to that of the Habo preparation. Furthermore, by N2 gas adsorption method, S li l
', T-method surface area (SA: l was measured,
9.]m"/'gr, which shows the desired value required for the raw material 4'(1',',(J) for video use.

When six dried pieces of CO dust-precipitated iron oxyhydroxide particles were subjected to electronic microscopic observation at 60,000x magnification using a standard method, it was found that the smallest units were well-aligned acicular fine particles. The thickness is mainly long axis (L): 0.2μ, short / L
Qh! D): o, o1μ.

<Actual Example 2> M11 & Co co-precipitated oxy-7-hydroxide f-arsenic particles were synthesized in exactly the same manner as in Experiment-1 except that the charging and reaction temperatures were changed to 55°C.

The fine particles had a specific surface area of 40 m2/gr1, a long axis of 204 μm and a short axis of 2092 μm, and exhibited the desired 1 axis required for raw material fine particles for audio applications.

Example 71 - Ro ~ 5> In substantially the same manner as in Experiment 1, tin & CO co-precipitated water iron fine particles were synthesized under various conditions of composition and reaction temperature. The results are summarized in Table 1.

From the above results, the water solubility λ,! In the 1/n&co co-precipitated oxyhydroxide ratio iron clove particles using n & CO compounds,
)! Both components n and CO are co-precipitated to approximately the charging value A,
In fact, it can be seen that the particle shape is clearly acicular, and exhibits well-developed anisotropy with an axial ratio of 20 or more.

Synthesis example of tun&co co-precipitated iron oxyhydroxide [Comparative example-
1] In the present compound 4'& f71J, an example of synthesis of oxy-7-hydroxide i';I [particles is shown (Table 2).

Experimental Example-6) In the method of Experiment 1 υ-1, MnSO4・5H2
0:1.1 gr (: 025 gr as Mn),
and CaSO3"7 N2Si: "+, 2gr (:
A similar neutralization/oxidation reaction was carried out using Co (D: 25 gr) and a charging and reaction temperature of 35°C.

The obtained iron oxyhydroxide fine particles have a weight ratio of 1.sum and C0 component to FQ of 0.05/100 and 0.05.
/ioo was contained.

In addition, the specific surface area was 95.0 m"/g'. However, according to the results of particle shape observation using an electron microscope,
Although it is basically a slanted shape, the average size of the long axis is Oj2 Nor and A1 (II: a, a + oμ), and the anisotropy was not as large as that of the Samurai.

<Example-7~+o) Experiment 1 In almost the same way as Cree-1, (2in & CO
1) Composition and reaction temperature of iron oxyhydroxide fine particles
Synthesized under Sato conditions. The results are summarized in Table 2.

However, from the above results, even if the method of the present invention is not used, even if the method of the present invention is not used, even if the method of the present invention is not used, even if the method of the present invention is not used, even if the method of the present invention is not used, even if the method of the present invention is not used, However, it can be seen that the L-line formation is completed after 1013·5, and the anisotropy of the shape cannot be said to be as developed as in the case of the method of the present invention. Furthermore, Mn
In comparison with the case where no &CO components are included at all, the simultaneous co-precipitation of Oki/Water 1 iron imitation by the method of the present invention has dramatically developed compared to the case where either one is used alone. I understand.

f-2. Synthesis comparative characteristics of iron oxyhydroxide 1: Regarding the Mn & Co content, the prepared value and the analytical value are shown.

Note 2 = In all examples, all basic units of acicular fine particles were used.

[Example 2] - Production of reduced iron powder In this example, iron oxyhydroxide fine particles introduced by co-precipitation of Mn & Co by the method of the present invention described in Example 1 above were used as raw materials. An example will be shown in which reduced iron powder is produced by applying adhesion modification treatment using a particle shape retaining component containing zinc borate, and then performing a catalytic gas phase reduction reaction using N2 gas.

<Experimental Example-11> Mo & Co co-precipitated iron oxyhydroxide fine particles described in Experimental Example-1 of Example-1 (SA = 95 772
A paste-like material with a solid content of 200 gr (126 gr as Fe) was prepared and put into an experimental scaler made by Ishikawa Kogyo (≠18-capacity 25 t). , performs Mixed God.Next is the one made by Boranox Company in the United States 442%, h) (2B203
・3ZnO φ3. 5 H2O
- -(Name: 2535) 5gr (: 4.8gr as B) is added little by little ((B/F
c = 0.39/100).

1. After 6 hours of continuous practice, a creamy, fine-textured base will be formed. This paste-like material is placed in a dry smoker set at 110° C. and then dried. 1. Crush the dried product using a wooden hammer, 6.
Obtain ~16 grains of menoshi.

Next, it was set in a Matsufuru furnace and calcined at 400°C to prepare an original material for reduction.

Next, uniform heating 11i in the gas flow direction is provided with a preheater for the reaction gas and a fluidized bath made of SiC powder, etc.
lI to XI possible 15 inch inner diameter steel pipe reactor,
Calcined powder 72gr (: 50gr as iron powder)
N2 gas was introduced at a supply rate of 100 ONt/H, and a reduction reaction was carried out at 650° C. for 5 hours. After the reduction reaction is complete, switch to N2 gas, cool to room temperature, and be careful not to contact the atmosphere. At the same time, the iron powder was recovered in a toene solvent to obtain reduced iron powder.

A part of the toluene-soaked reduced iron powder was dried by the transpiration method in a glove box with a flow of N2 gas flowing through it), and the specific surface was measured with a 1,11-3Ki microscope using a powder χ
~Load the specified amount into a sol/sol holder for a glandular diffraction measurement device/magnetic property measurement device, and use a portion of each for 11 hours.

The reduced iron powder is long-sleeved (L):, -ta02/l, short! !I'!] (
D): Shows a skeleton particle shape that closely reflects the shape of the oxide/iron hydroxide fine particles used as the raw material with a diameter of about 0.1 μm, and furthermore, the shape of the skeleton particles is formed by close stacking of spherical ultrafine particles with a diameter of approximately 0.01 μm. and non-porous t! 11) It was found that the structure was expressed.

According to the results of specific surface area measurement, the specific surface area of the reduced iron powder (
S7\) was 650 ft/gr.

According to powder X-ray diffraction measurement, the reduced iron powder exhibits an α-phase and a crystallite size (os) in the normal direction of the (110) plane.
was about 120λ.

The results of magnetic property measurement are coercive force (HC): 1400
0e1 saturation magnetization (σs): 175emu/g
r% squareness ratio (Rs): 0.501.

As described above, it can be seen that the reduced iron powder obtained by the method of the present invention exhibits an acicular property that closely follows the shape of the raw material iron hydroxide fine particles, and also has sufficiently high magnetic properties.

<Experimental Examples 12 to 15> Experiments according to the method of the present invention obtained in Experimental Examples 2 to 5 described in Example 1 in exactly the same manner as Experimental Example 11. 4); Oxygen/iron hydroxide fine particles were Production of reduced iron powder used as raw material 1
The characteristics are summarized in Table 3.

From the above results, the reduced iron powder produced by the method of the present invention can be used with all raw materials of iron oxyhydroxide fine particles oriented toward finer graining for further improvement (Experimental Examples 12, 14; and 15), -
Using ultrafine particle type oxygen/iron hydroxide fine particles as a raw material with the intention of video use (Examples 11 and 13),
It is clear that both exhibit acicular properties well inheriting the shape of the raw material iron hydroxide 9 particles, and that HC, σS, and Rs also provide sufficiently satisfactory characteristic values.

Table 3. Production Example of Reduced Iron Powder Sho 1: In either case, I9. The shapes of the iron oxyhydroxide fine particles are shown based on Shape 14 particles.

6 Mi2: It is shown as the crystallite size iGs in the direction of the (110)-plane of α-phase iron powder.

[Ratio 1 reduction example-2] In this comparative example, regarding magnetic powder intended for video use,
A method for adhesion modification of a particle shape-retaining component using conventional type iron oxyhydroxide fine particles not produced by the method of the present invention and fine particles of iron oxyhydroxide produced by the method of the present invention as raw materials, and for the former not produced by the method of the present invention. and an example in which reduced magnetic iron powder is produced by H2 reduction reaction with addition of the method of adhering and modifying the particle shape retaining component according to the method of the present invention; Add law and H
An example of producing a reduced magnetic iron material by a 2-reduction reaction is shown (Table 4).

<Experimental Example-16> In fact, needle-like iron/water [42 iron fine particles (Mn & Co co-precipitated type, S
/\= 95tn'/ grs L /D = 20
) as raw material and 200 gr (:F
(126gr as c) was collected, about 61 g of pure water was added thereto, and stirred with a high speed mixer to prepare a turbid liquid.

Next, the 10th section aluminic acid nodium iii 90CC (
: Add 2.96gr (as A-1) little by little, then add 80cc of water (2.94gr as A-1) in a small amount.
gr ) F will be controlled by a small amount. Next, the system was neutralized to pH = 7 by dropping a trace amount of hydrochloric acid, and then filtered.
By drying and pulverizing, fine particles of iron 7-hydroxide with Al-5i adhesion and denaturation are obtained.
858, refer to the method of Implementation 14/1J-1)
.

Next, in almost the same manner as in Experimental Example-11, it was subjected to a calcination treatment at 400°C and then subjected to an H2'iX elementary reaction at 400°C.
Al-5i modified reduced magnetic iron powder was produced.

The characteristics of the reduced magnetic iron powder were evaluated in the same manner as in Experimental Example 11. First, the results of observation under an electron microscope were as follows: ・'Accordingly, the shape of the acicular iron oxyhydroxide fine particles used as the raw material was well-defined. Although the inherited vestigial particles were shown, it was observed that spherical ultrafine particles of about 0.0015 μm were connected in a beaded manner, and a porous structure was expressed.

According to the results of specific surface area measurement, SA was 72.2 mV.
It was gr. According to powder X-ray diffraction measurements, an α-phase was formed, and the crystallite size in the direction normal to the GS, ie (110)-plane, was about 170×. Magnetic properties ii!
'I'ITE: :L', according to i, HC=i4
000e, 6s=180emu/Q+, hs=o4
It was 9B.

As mentioned above, the method of the present invention produces oki/
A conventionally known method that uses iron hydroxide fine particles as a raw material. In the reduced magnetic iron powder produced by the method of adding Al-8 + adhesion modification,
It is rich in needle-like properties and exhibits excellent magnetic properties, but
The particle shape is a porous necklace type in which spherical ultrafine particles are connected in a beaded manner, which is significantly different from the particle shape of the reduced magnetic iron powder based on the fracture modification method of the present invention described in Experimental Example 11. It was obvious that there was a difference.

<Experiment Example-17> Oquine iron hydroxide fine particles described in Experiment 111-7, which are not based on the method of the present invention (component f, j:, no components, s7)::95yn2/ gr1L/D −”
) was prepared in the same manner as in Experimental Example 16 using Al-
A 5i-adhered modified powder was prepared, and a H2 gas reduction reaction was carried out under the same conditions as before to produce a reduced 1-kuni magnetic pouring iron powder.

The iron powder showed skeletal particles that inherited the shape of the raw material iron oxyhydroxide fine particles, but it had a porous necklace shape as in Experimental Example 16. o2
/gr, OS is approximately 185 people, magnetic characteristics are HC = 14
150e, c+s=178emu/gr, Rs=0.
It was 497.

Even in the case of reduced magnetic iron powder produced by the conventional method in which A-1-31 adhesion modification is added to the acicular oxide/iron hydroxide fine particles that are not produced by the method of the present invention, as described above, the apparent The upper one shows acicularity and exhibits characteristics that are disappointing for the magnetic frame Y, but the particle shape has a low axial ratio and is a necklace type in which spherical ultrafine particles are connected in a bead shape. It is clear that the shape of the particles is significantly different from that of the reduced magnetic iron powder based on the deposition method of the present invention described in No. 11.

<Experimental Example-18> Acicular oxidation/iron hydroxide fine particles described in Experimental Example-7 and not according to the method of the present invention (: no coprecipitated component, S A = 95
17+27 grz L/D=10) as original F
As a result, a b-thread-covered modified powder was prepared according to the method of the present invention described in 11. Perform a gas reduction reaction and reduce the reduced magnetic iron powder to 13'! , ;q Shita.

The iron content showed skeletal particles that inherited the shape of the raw iron oxyhydroxide fine particles, and a dense layered structure of spherical ultrafine particles of about 0.012 μm was observed, indicating a non-porous morphology. Also, the iron powder has an sA of 585 m2/gr, C)
iE is about 145 flame, magnetic properties are HC=14050e
.

c+5=177 emu/gr, Rs=0.496.

As mentioned above, even when using acicular iron oxyhydroxide fine particles that are not produced by the method of the present invention, B.
- In the reduced magnetic iron powder obtained by adding fracture modification, it shows a porous acicular f'i4 particle shape,
Although it exhibits excellent magnetic properties, the acicularity of the skeleton particles and the size of the spherical ultra-fine particles constituting them are different from those in Example-
Reduced magnetism 1-1, which is significantly different from the iron powder described in No. 11, is made from iron 7-hydroxide fine particles rich in nail-like properties obtained by the method of the present invention, and is based on the adhesion modification method of the present invention.
-It was obvious that the particle shape of iron (Zudo 7) and (1) were significantly different.

64 Characteristics of Reduced Iron Powder for Video 1: In all cases, the shape of the iron oxyhydroxide fine particles as a raw material is basically shown.

Pouring=Experimental Example-16417 exhibited a porous necklace-like internal structure.

In the example of pouring = Experimental Example-18, a non-porous internal structure was shown, but the ratio of shell particles to flesh was low.

[Comparative Example-6] In this comparative example, regarding magnetic powder intended for audio use, conventional type iron oxyhydroxide fine particles not produced by the method of the present invention and iron oxyhydroxide fine particles produced by the method of the present invention were used as raw materials. Regarding the former, an example is shown in which reduced magnetic iron powder is produced by a H2 reduction reaction in addition to a method of adhesion modification of a particle shape retention component not based on the method of the present invention and a method of deposition modification of a particle shape retention component according to the method of the present invention. Regarding the latter, an example is shown in which a reduction magnetic iron powder is produced by an H2 reduction reaction in addition to a method of adhering and modifying a particle shape-retaining component that is not based on the method of the present invention (Table 5).

<Experimental Example-19> Acicular iron oxyhydroxide fine particles (Mn, & Co co-precipitated type, 5A=
40m2/gr, L/D=20) was collected as a solid content of 200g (126gr as Fe), added about 63ml of pure water, and stirred with a high speed mixer to prepare a water hardening mixture. do. Next, add 90cc of aluminic acid solution (2.96gr as Al) dropwise little by little, and then heat the mixture with 65%-8I.
02 hydraulic lath liquid 180cc (: s i as 2
．． 94g) little by little. Next, Section 1-
The system is neutralized to pH=7 by dropping a small amount of hydrochloric acid, and then filtered, dried, and pulverized to obtain dried granules of Al-5/adhesion-modified iron oxyhydroxide fine particles. 52-134
858, referring to the method of Example-1).

Next, in almost the same manner as in Experimental Example-12, it was subjected to a calcination treatment at 400'C and then subjected to an H2 reduction reaction at 400°C.
Al-5i modified reduced magnetic iron powder was produced.

When the characteristics of the reduced magnetic iron powder were evaluated in the same manner as in Experimental Example 12, first, according to the results of electron microscopic observation, it was found that the shape of the acicular iron oxyhydroxide fine particles used as the raw material was well inherited. Although the particles showed only superficial particles, it was observed that spherical ultrafine particles of about 0.0025 μm were connected in a bead-like manner, creating a porous structure.

According to the results of the determination of the specific surface area, SA is 56.0 m2
/ gr. According to powder Xa diffraction measurement, an α-phase was formed, and the crystallite size in the normal direction of GS, that is, (iIO)-UjiO, was about 24OA. According to the magnetic property measurement results, Hc=12500e1σ5=1B6
ernu/gr, Rs=0.485.

Based on the above, reduced magnetic iron powder produced by the method of the present invention using iron oxyhydroxide fine particles rich in acicularity as a raw material and adding Al-5/adhesive modification to the powder has no acicular properties. The particle shape is a porous necklace type in which ultrafine spherical particles are connected in a beaded manner, and the particles of the present invention described in Experimental Example 12 have a special shape with excellent magnetic properties. It is clear that the shape of the particles is significantly different from that of reduced magnetic iron powder based on the deposition method.

Experimental Example-20> Acicular iron oxyhydroxide fine particles described in Experimental Example-8 and not according to the method of the present invention (: no coprecipitated component, 5A=39+f
/gr, L/D=11) as raw material, Experimental Example-1
Al-5/deposited modified powder was prepared in the same manner as in Example 9, and an H2 gas reduction reaction was carried out under the same conditions as in the above to produce L iron powder as reduced magnet 1.

B71< powder is the shape of the raw material iron oxyhydroxide fine particles h
411, but as in the case of Experimental Example-19, it was like a porous necklace, and the EiA was 3.
6.011f/gr, OS is about 25OA', magnetic properties are Hc=12450e, σs=190emu/
gr, Rs=0.484.

As mentioned above, the reduced magnetic iron powder obtained by using the acicular iron oxyhydroxide fine particles that are not obtained by the method of the present invention as a raw material and by the conventionally known method in which Al-5i adhesion modification is added also has the appearance of needles. However, the particle shape has a low axial ratio and is a necklace type in which spherical ultrafine particles are connected in a bead shape, and the present invention described in Experimental Example-12 It was obvious that the particle shape of the reduced magnetic iron powder was significantly different from that of the reduced magnetic iron powder based on the adhesion modification method.

Experiment IJ-21) Acicular oxyhydroxide f arsenate fine particles (: no coprecipitated component, SA = 39
m"/grXL/D=11) as a raw material, B-g modified powder was prepared by the method of the present invention described in Experimental Example 12, and further an H2 gas reduction reaction was carried out under the same conditions to obtain reduced magnetic iron. produced powder.

The iron powder exhibits skeletal particles that inherit the shape of the raw iron arsenate oxyhydroxide fine particles, and has a porous shape with a laminated structure of spherical ultrafine particles of about 0.020μ. Also, the iron powder has an SA of 5?I/gr, an O3 of about 22OA, a magnetic special order of Hc=12500e, and a C
ts=190emu/grXRs=0.484.

As shown in ``2'' below, even when acicular iron oxyhydroxide fine particles not produced by the method of the present invention are used as raw materials, reduced magnetic iron powder produced by the method with B-adhesive modification added by the method of the present invention shows a non-porous acicular skeleton particle shape and exhibits the characteristics used for magnetic properties, but the acicularity of the skeleton particle and the size of the spherical ultrafine particles constituting it are different from Example-12.
It is significantly different from the case of the described iron powder, and the reduced magnetic iron is made of arsenic/hydroxide fine particles rich in acicularity obtained by the method of the present invention, and is based on the adhesion modification method of the present invention. It is clear that the particle shape of the powder differs greatly.

Table 5. Manufacturing ratio of Tokumoto iron powder for audio! j〆7 Example 8:
1: In either case, the shape of the raw material iron oxyhydroxide particles is basically shown.

Note 2 = Experimental example - 19ec 20 Nolfl has a porous necklace-like interior;! I showed Suzo.

Note 3: The example of Experimental Example-21 showed a non-porous internal structure, but the axial ratio of the skeleton particles was low.

[Example-6] - Gradual oxidation of reduced iron powder In this example, the reduced magnetic iron powder obtained by the method of the present invention described in Example-2 was subjected to gradual oxidation, and the surface layer of the fine particles was oxidized. (Tables 6 & 7) show the customization of the system with a layer and a stable fhi treatment.

<Experimental Example 22> The reduced iron powder soaked in toluene described in Experimental Row 11 is spread thinly and uniformly on a quarter-sized enamel batt and transferred. While the bottom of the vat is cooled with ice water, a gentle airflow is passed over the top of the vat to evaporate and scatter toluene. Thus, after about 5 hours, Xi! ! By utilizing the latent heat of vaporization of all toluene, a slow oxidation reaction progresses, making it possible to form a df film on the surface layer of the particles (:
Hereinafter, this acid ratio method will be referred to as air-drying treatment, and the reduced iron powder based on this treatment will be referred to as air-dried iron powder).

The specific surface area SA of the air-dried iron powder is 6o, om7gr,
A decrease in 5SA was observed due to gradual oxidation. Also, the magnet, q;
p[raw, Hc21,48[] Oe, as=130
emu/gr, RS = 0.500, and an increase in the HC value and a decrease in the σS value were observed with gradual withdrawal.

The ignition point was measured at 90°C (heating rate = 50°C/min).

<Experimental Examples 23 to 26> The toluene-soaked reduced iron powder based on the method of the present invention described in Experimental Examples 12 to 15 was air-dried in the same manner as the method described in Experiment 91-22, and the specific surface area Magnetic properties and ignition points were measured and evaluated (However, in the case of ignition point measurements for air-dried iron powder for audio applications, the temperature increase rate was 20°C/min.

(closed).

The results are shown in Tables 6 & 7. From now on, the reduced iron powder produced by the method of the present invention will form a suitable oxide film as a result of air-drying, and will exhibit characteristics required for magnetic materials for audio and video applications in terms of specific surface area and magnetic properties. As is clear from the comparative example, the ignition point is relatively high due to the non-porous particle morphology and the handling properties are improved.

Table 6 List of properties and comparison of air-dried iron powder for video use Note 1 = In either case, the specific surface area and magnetic properties for video use are maintained.

Note 2: The ignition point is expressed as FP.

The temperature increase rate was 50° C./min.

In Experimental Examples-27&-2B, Experimental Examples-22, -25&-2
It is recognized that the ignition point is lower than that of 9.

Table 7 List of characteristics and comparison of air-dried iron powder for DIO-DIO (Note 1)
: In either case, the specific surface area and
Possesses magnetic properties.

Note 2: Displayed as ignition point 2rp.

The heating rate was 20°C/min.

'A Experiment Number - In 50 & 31, experiment fl! -24, -2
The lower ignition point is lower than t2 compared to 5&-32.

[Comparative Examples - 4] In this Comparative Example, the reduced magnetic iron powder described in Comparative Examples 2 to B, which is not based on the method of the present invention, was subjected to gradual oxidation, and an oxidized layer was provided on the surface layer of the fine particles to stabilize it. The properties of the treated system are shown (Tables 6 & 7).

<Experimental Example 27> Air-dried iron powder was prepared from the toluene-soaked reduced iron powder described in Experimental Example 16 in the same manner as described in Experimental Example 22. The specific surface area SA of the air-dried iron powder was 605 m''/gr, and a decrease in SA due to slow oxidation was observed.
, Hc = 14900e, σs = 125 emu /
gr,, R3 = 0.497, H due to slow oxidation
An increase in C-value and a decrease in σS-value were observed.

Next, the air-dried iron powder was subjected to ignition point measurement in the atmosphere.
The temperature was 70°C (: temperature increase rate = 50°C/min).

<Experiment 1 Guto 28 to Ro 2> The reduced iron powder immersed in toluene and not according to the method of the present invention described in Actual/Inspection-17 to 21 was air-dried in the same manner as the method described in Experimental Example-22. , specific surface area, magnetic properties, and ignition point were measured and evaluated (= However, in the case of ignition point measurement for air-dried iron powder for audio use, the temperature increase rate was 20°C/min.

(closed).

The results are shown in Tables 6 & 7.

From the above results, the characteristics of the air-dried iron powder that is not subjected to the adhesion modification method of the present invention are that although it has physical properties suitable for video and audio applications in terms of specific surface area and magnetic properties, it is difficult to handle in terms of ignition point. It was found that the characteristics of the method of the present invention, which achieves a custom-made non-porous particle morphology, are clearly demonstrated.

[Example 4] - Manufacture and evaluation of magnetic tape In this example, the air-dried iron powder obtained in Example 6 by the method of the present invention was used to form a paint and coating, and a magnetic tape was manufactured. death,
Examples including characteristic evaluation are shown (Tables 8 to 10).

<Experimental Example-63> Collect 10g of air-dried iron powder described in Experimental Example-22, put it into a pot with an internal volume of 550 mm along with the following materials, and add rice.
7 Continue mixing and dispersing for 10 hours with a paint shaker manufactured by Notetevil (= t dimension, 2 m, as dispersion media)
/m diameter α-alumina beads).

0 US - UCC salt vinyl acetate poly? -VA()H: o
, af ・Polyurethane NL 2448 manufactured by Mitsui Toatsu Chemical Co., Ltd.:
1.2 gr - Inuhe Kagakusha phosphate ester A P-15: 0.5g
r・α-Alumina AKP-50 manufactured by Sumitomo Chemical Co., Ltd.: 0.2g
r-solvent toluene: 15gr, MEK: 15gr
Thereafter, the dispersion media was separated to make a magnetic paint, and coated with an applicator using a magnetic tape specification precision coater.
Polyester film manufactured by Atsuno Toshi Co., Ltd.: Lumirror (:
16w-Qo6s).

Thereafter, the coated film surface is smoothed by calender roll treatment, and then heat treated at 50° C. for 2 days to complete the polyurethane curing reaction.

It was cut into 1/2-inch pieces to make magnetic tape of current home video specification size.

<Magnetic property evaluation> When the magnetic custom made magnetic tape was measured and evaluated, Hc=1
4000e, residual magnetic flux density Br = 2010 C), squareness ratio Br /Bm = 0.796, it sufficiently shows the magnetic properties of the tape required for 8 m / m video, and moreover, the book described below As is readily apparent when compared with the magnetic properties of a magnetic tape made from a reduced iron powder system not according to the invention, it exhibited a uniquely high squareness ratio (Br: 73m).

<Evaluation of video characteristics> First, we modified the circuit of a commercially available home video deck (model HRD-120 manufactured by Victor Corporation of Japan) so that the oral transmission speed of the head could be reduced to half speed, and then added a Sendust video deck manufactured by Mitsumi Electric Co., Ltd. Head 1Ji2, 8m/m V
It was modified to provide a recording/playback function in accordance with the TR recording specifications, and was used as a video characteristic measurement/evaluation device.

Optimized playback output of the prototype magnetic tape (: Y-OUT and 7-c/N
) was measured, Y-OUT = +4.7dB%
Y Ribe-1-1-5.5 dll was obtained, and a custom-made magnetic tape with a sufficiently higher output was obtained compared to the custom-made magnetic tape of the reduced iron powder system that did not use the method of the present invention, which will be described later.

・Experiment Example-34〉 Using the air-dried iron powder described in ZJ-23, experiment ㅅ]-
At the same time as 53, they manufactured magnetic tapes sized to home video specifications.

<Magnetic property evaluation> When the magnetic custom made magnetic tape was measured and evaluated, Hc=1
4500eX Br=2000G, Br/Bm=0.
810, which sufficiently shows the magnetic properties of the tape required for 13 nl/'m video, and also has a uniquely high squareness ratio (:
Br/T31TT) was awarded No. 1.

<Video characteristics ii/evaluation> Y-OUT = +5.2rJB XY-I = 16.
odB was obtained, and a sufficiently high output custom order was obtained.

Collect 10g of air-dried iron powder described in 1kl-24 and put it into a bot with an internal volume of 55Qd along with the following materials.
Continue mixing and dispersing for 5 hours on 7 acres of paint manufactured by Red Devil, USA (as a bidispersion media, 2m/m
α-alumina beads of the same diameter were used. )・Salt vinyl acetate polymer VAGH manufactured by UCC, USA: 1. Or Polyurethane NL-2448 manufactured by Mitsui Toatsu Chemical Co., Ltd.: 1
．． Ogr ・Kagakusha phosphate ester AP-13 = 0.2gr・
α-Alumina AKP-30:0.2 manufactured by Sumitomo Chemical Co., Ltd.
gr/Solvent Toluene: 14gr, MEK: 14gr After separating the dispersion media to make a magnetic paint, use an applicator with a magnetic tape specification precision coater to apply a 12μ thick polyester film made by Toshisha Co., Ltd.: Lumirror (:12
Coat on B-Ll 0).

Thereafter, the coated film surface is smoothed by calender roll treatment, and then heat treated at 50° C. for 2 days to complete the polyurethane curing reaction.

It was cut to 3.81 m x 7 m to make a magnetic tape of the current compact cassette specification size.

<Magnetic property evaluation> When the magnetic properties of the magnetic tape were measured and evaluated, ) (C=
11180e, Br"Roro DOGX Br/Bm
==0.880, which sufficiently shows the magnetic resistance of the tape required for audio use, and is also compared with the magnetic resistance of the magnetic tape made from the reduced iron powder system not according to the present invention, which will be described later. It showed a uniquely high squareness ratio (Br/Bm), as was immediately apparent after one bite.

Audio 1J performance evaluation> Tape tester manufactured by Nippon Columbia: DENON = 0.3
Using 1R (equipped with IEC standard head), Japan magnetic tape standard: MTS = 0.101 ('72)
According to the described measurement method, the audio characteristics were measured and evaluated using the EC standard Type-V tape as a standard.

Low frequency sensitivity (: 333R2 sensitivity) is +1.5dB, high frequency sensitivity (: 20kHz2 sensitivity) is +2.8dB, maximum output (
2nd episode IVIOL) is +6.6dB X saturation output (:
1 kHz sor, ) was +0.5 dB, which, as will be readily apparent from the comparative example described later, showed high sensitivity and high output that are more than sufficient for audio use.

Furthermore, the AC bias noise (:NaC) is -57,0
dB, indicating a sufficiently low custom order.

<Experimental Examples-56 to 37> Using the air-dried iron powder described in Experimental Examples-25 to 26, Experimental Example-6
Produce an audio tape in the same manner as in 5.
We conducted measurements and evaluations of its magnetic properties and audio customization. The results are shown in Tables 8-10.

These results show that when reduced iron powder produced by the method of the present invention is used, magnetic customization with an unprecedented squareness ratio can be achieved, and this fact is directly reflected to provide greatly improved electromagnetic conversion characteristics. The thing has become clear.

Table 8, 1 Results of evaluation of magnetic characteristics of magnetic tape for video use - Roughness The squareness ratio of the reduced iron powder based magnetic tape produced by the method of the present invention (=Experimental Example 33434) is uniquely high.

Note 2 = In the case of Experimental Example-63 using iron oxyhydroxide fine particles produced by the method of the present invention as a raw material, the squareness ratio of the tape was relatively high, but the residual magnetic flux density was low.

Table 82 List of magnetic property evaluation results of magnetic tapes for audio use Note: The reduced iron powder based magnetic tapes produced by the method of the present invention (=Experimental Examples -35 to 37) have a uniquely high squareness ratio.

Note 22 In the case of Experimental Example 41 using iron oxyhydroxide fine particles produced by the method of the present invention as a raw material, the squareness ratio of the tape was relatively high, but the residual magnetic flux density was low.

Table 9 '8m7mVTR' of magnetic tape for video use
Characteristics list Note 1 = Modified commercially available rough-hewn TR deck, 8m
/ m It was used as a recording/playback function device based on VTR specifications.

Note 2 = In the magnetic tape of the reduced iron powder system according to the method of the present invention (: Experimental Example-55 & 34), the Br/Bm-value and the Br
It is characteristic that the output is high in response to a high -value, and in particular, the output noise ratio is high in response to a low GS-value.

Table 10 List of evaluation of electromagnetic conversion characteristics of magnetic tapes for audio applications Note: In the reduced iron powder system magnetic tapes with the configuration of the present invention (: Disaster Examples-35 to 67), B r / B m-
It is characterized by a high output corresponding to a high value and a high Br value, and a high noise ratio corresponding to a small G5-1 direct.

[Comparative Example-5] In the first case of this invention, the air-dried iron powder described in Comparative Example-4, which is not based on the method of the present invention, was used to form a paint and coating, and a magnetic tape was manufactured. Examples with additional characteristic evaluations are shown (Tables 8 to 10).

<Experimental Examples 68 to 4> In the same manner as Experimental Examples 33 to 67, magnetic paints for video or audio applications were prepared and magnetic tapes were manufactured.

Similarly, the magnetic properties, video properties, and audio properties of the prototype magnetic tape were measured and evaluated, and the results shown in Tables 8 to 10 were obtained.

From the above results, in the case of reduced iron powder produced by the method of the present invention,
Due to the extremely high squareness ratio and large residual magnetic flux density, the output characteristics are high, and the noise is low due to the small spherical ultrafine particles that make up the skeleton particles, that is, the crystallites. I understand.

Furthermore, even when iron oxyhydroxide fine particles with greatly developed acicular properties obtained by the method of the present invention are used as a raw material and an adhesion modification treatment other than the method of the present invention is performed, a relatively high squareness ratio is achieved. , is still lower than when the adhesion modification treatment is performed by the method of the present invention, and it is clear that the gain in the output is insufficient and the noise is high due to the large crystallite size.

Furthermore, even when iron oxyhydroxide fine particles not produced by the method of the present invention are used as a raw material and subjected to adhesion modification treatment by the method of the present invention, the crystallite size is relatively small.
Compared to the method of the present invention using iron oxyhydroxide fine particles with greatly developed acicular properties as a raw material, it is clear that the output is not sufficiently high due to the large size, high noise, and low squareness ratio. It is.

From the above results, it is possible to use magnetic arsenic oxyhydroxide fine particles with greatly developed acicular properties as a raw material and to add an adhesion modification formulation mainly containing zinc borate according to the method of the present invention. This is a necessary condition for making the squareness ratio uniquely high and the residual magnetic flux density sufficient, resulting in a large gain in the output characteristics, and for the noise to be sufficiently low due to the small crystallite size. It can be said that it has become clear that

[Example 5] - Evaluation of deterioration over time of prototype tape In this example, high temperature evaluation of the prototype magnetic tape for video or audio/video applications of the reduced iron powder system obtained by the method of the present invention obtained in Example 4 was conducted. - The results of evaluating the deterioration of coating film properties and magnetic properties under humid environmental conditions are described (Tables 11 and 12).

Experimental Examples -44 to 45> The magnetic tapes for video use described in Experimental Examples -65 and -54 were subjected to aging acceleration treatment experiments for one week in an environment of 60°C and 90% relative humidity to determine the coating film properties and The deterioration characteristics of magnetic properties were evaluated.

First, in all cases, no major changes were observed on the surface of the magnetic coating, and only slight convexities were observed here and there.

Next, the magnetic properties of the magnetic tape of Experimental Example-44 are as follows: Hc=1450 0e (:△HC=+3.61)B
r=1905 G (:ΔBr=-5.2%). In addition, in the case of the magnetic tape of Experimental Example-45, Hc = 1510 0e (: △HC = -1-4.1%)B
r=1880 G (:ΔBr=-6.0%). This result could be judged to have sufficient weather resistance in comparison with the comparative example described below.

<Experimental Examples 46 to 48> The magnetic tapes for audio applications described in Experimental Examples 35 to 57 were subjected to aging acceleration treatment experiments for one week in an environment of 60° C. and relative humidity of 90 parts, to determine the coating film properties and magnetic properties. The deterioration characteristics of the characteristics were evaluated.

The results are shown in Tables 11 and 12, and these results can also be judged to have sufficient weather resistance from comparison with the comparative examples described below.

Table 11 Evaluation of deterioration characteristics over time of magnetic tapes for video use - Properties 1 An acceleration test over time was added under environmental conditions of 60° C. and RH 90% to measure the deterioration characteristics of magnetic properties.

Note 2: In the nine lines of iron powder produced by the method of the present invention (experimental example-44645), there was little deterioration of HC&Br.

Table 12 Inadequacy of transport time of Fujiday No. 18 Discontinued Tape 1
A aging acceleration test was added under the environmental conditions of iPr and Roughness 1: 60° C. and RH 9 (7%) to determine the deterioration characteristics of the magnetic properties σi11.

Note 22 In the reduced iron powder system produced by the method of the present invention (Experimental Examples-46 to 48), there is little deterioration of HC&Br.

[Comparative Example 6J In this example, we will discuss the environmental conditions under high temperature and high humidity of the prototype magnetic tape for video or audio applications of the reduced iron powder system obtained in Comparative Example 5, which is not based on the method of the present invention. We will describe the results of evaluating the deterioration characteristics of the coating film properties and magnetic properties.
Tables 11-12).

Experimental Examples 49 to 53> The magnetic tapes for video use described in Experimental Examples 38 to 43 were subjected to aging acceleration treatment experiments for one week in an environment of 60°C and 90% relative humidity to determine the coating film properties and magnetic properties. The deterioration characteristics of the characteristics were evaluated.

First, except for the magnetic tapes in Experimental Examples 51 and 54, the surface of the magnetic coating had minute convexities all over it, and rust caused by the oxidation of iron powder. It can be seen that this was greatly expressed.

Experimental example - Experimental example 51 using magnetic tapes 38 & 43
In the case of &54, the occurrence was similar to that seen in the experimental example described in Example-5.

Next, in the case of the magnetic tape of Experimental Example-49, the magnetic properties are as follows: HC=1490 0e (:△HC=+4.9%)B
r=1620 G (:△Br= -io, o%
)Met. The other results are summarized in Tables 11 and 12, and in all cases, compared to the magnetic tape group of the reduced iron powder system produced by the method of the present invention, the deterioration of magnetic properties was worse, and the magnetic medium was However, the results showed that the aging characteristics, which are indicators of reliability, had some drawbacks.

From the above results, it is clear that magnetic iron is made from fine particles of iron 7-hydroxide with greatly developed acicular properties obtained by the method of the present invention, and is subjected to reduction and deacidification through the adhesion modification formulation according to the method of the present invention. Magnetic tapes made from powder do not show any major changes in the properties of the magnetic coating surface even when exposed to accelerated deterioration due to bumps in high temperature and high humidity environments, and do not exhibit large changes in the magnetic properties of custom-made magnetic films. There was nothing to show.

[Summary of the functions and effects of the invention]

Based on the results of Examples and Comparative Examples shown in comparison with Part 9, the effects and effects of the present invention can be summarized as follows.

That is, in a method for producing ferromagnetic metal powder fine particles as a magnetic material in a magnetic recording medium suitable for high-density magnetic recording, oxine hydroxide containing Mn & Co as coprecipitated components by the method of the present invention is used. (1) Oxyhydroxidation by using arsenic fine particles as a raw material and making reduced iron powder through calcining, reduction, and gradual oxidation after undergoing an adhesion modification formulation using sparingly soluble zinc borate as a superstructure according to the method of the present invention. Regarding iron fine particles, (a) they exhibit an acicular particle shape that does not contain twins or dendrites, (b) their acicularity is small, with a ratio of major and minor axes of 20 or more; ( 2) Regarding the reduced iron powder fine particles, (c) they exhibit a skeleton particle shape that closely follows the shape of the raw material iron hydroxide fine particles, and (2) no interparticle crosslinking, that is, sintering, is observed. e)
The spherical ultrafine particles constituting the skeleton particles are sufficiently small to a level never before seen, (f) and have a multi-layered structure that does not develop pores, and (g) due to after-oxidation. The change in magnetic properties is sufficiently small,
It is clear that it has a form and magnetism suitable for video and audio applications.

Furthermore, when a magnetic coating $+ is prepared by a conventional method using the magnetic iron powder fine particles and processed into a magnetic tape, (5) As for the magnetic properties, (5) ) It has a sufficiently high squareness ratio and a large residual magnetic flux density, and (4) It has sufficiently realized the characteristics required for video and audio applications. (4) 8 m/m VTR As for the characteristics, (i) the playback output/output noise ratio is sufficiently large; (5) the audio electromagnetic conversion characteristics are Ql;) the sensitivity/output is sufficiently large and the noise is sufficiently low; (6) Regarding reliability, it can be said that (a) it has been determined that (a) it has low deterioration over time in high temperature and humid environments, and the reliability index of the medium is high.

As shown in [below]-, the method of the present invention is extremely effective as a magnetic material for high-density recording media such as magnetic tape for 8 m / m video applications and magnetic tape for audio, which is a vast improvement over conventional products. The present invention provides a method for producing ferromagnetic metal powder particles mainly made of iron that exhibit high quality.

Claims (1)

[Claims] 1. Ferrous hydroxide fine particles are formed by a neutralization reaction between a ferrous salt and an excess alkali, and then air is blown to perform oxidation and crystallization to form acicular oxyhydroxide. Fine iron particles are synthesized, and after washing with water, a particle shape-retaining component is applied to the surface layer of the fine particles, followed by washing with water, drying, calcining, reduction, and gradual oxidation processes as necessary to produce stabilized ferromagnetic iron powder. (1) Adding a water-soluble manganese compound and a water-soluble cobalt compound to a ferrous salt to co-precipitate manganese and cobalt into acicular iron oxyhydroxide fine particles; (2) The weight ratio of manganese (Mn) and cobalt (Co) to iron (Fe) is Mn/Fe=0.1/100 to 10/100, Co/F
e = in the range of 0.1/100 to 10/100; (3) the particle shape retaining component contains zinc borate, and the content thereof is B/Fe in the weight ratio of boric acid (B) and iron; =0
．． A method for producing ferromagnetic iron powder, characterized in that the ferromagnetic iron powder is in the range of 05/100 to 5/100.