CN101064205B - Magnetic metal powder suitable for use in magnetic recording media and method of manufacturing the powder - Google Patents
Magnetic metal powder suitable for use in magnetic recording media and method of manufacturing the powder Download PDFInfo
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- CN101064205B CN101064205B CN 200710091889 CN200710091889A CN101064205B CN 101064205 B CN101064205 B CN 101064205B CN 200710091889 CN200710091889 CN 200710091889 CN 200710091889 A CN200710091889 A CN 200710091889A CN 101064205 B CN101064205 B CN 101064205B
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Abstract
The invention provides a metallic magnetic powder suitable for an coating type magnetic recording medium having a high recording density, wherein a level of a weathering resistance equivalent to a conventional one is maintained, while a saturation magnetization [sigma]s is high irrespective of a particle volume. The metallic magnetic powder for the magnetic recording medium is constituted as a powder which is composed of particles having a metallic magnetic phase and an oxide film with Fe or Fe and Co being a main component. Pending matters can be solved by preparing conditions that an average long axis length of the powder particle is 10-50 nm, an average particle volume containing the oxide film is equal to or less than 5,000 nm<3>, and (R+Al+Si)/(Fe+Co) atomic ratio calculated by using a value of a content amount (atomic%) of each element included in the powder particle is equal to or less than 20%. R is a rare-earth element (Y is treated as the rare-earth element also). This metallic magnetic powder is obtained by eluating a non-magnetic component after sintering by use of a complexing agent and a reducing agent.
Description
Technical field
The present invention relates to ferromagnetism metal dust and the manufacture method thereof in the application type magnetic recording media, used.
Background technology
Magnetic recording media take the data backup purposes of computer as representative is accompanied by high capacity, must further improve packing density.In order to reach high record density, need the little Magnaglo of particle volume.Even the applicant in order to respond such trend, has carried out the improvement take the manufacture method of patent documentation 1 record as all metallic magnetic powder manufacturing technologies of representative.
As the records such as existing disclosed document, metallic magnetic powder is representative with iron as main component.The metallic magnetic powder of iron system, industrial generally is after making it contain the such sintering preventing agent of Si, Al, rare earth element, alkaline-earth metal element in take FeOOH or iron oxide as the needle powder of main body, by the method for reducing manufacturing.
In the past, in order to improve the characteristic of Magnaglo, mainly be to improve the characteristic of Magnaglo itself how or prevent sintering, how to improve the such viewpoint of dispersiveness and study always.Disclose the atomicity ratio by regulation rare earth element on the surface of particle etc. in the patent documentation 2～5, used the magnetic particle that in this scope, comprises, obtained magnetic recording media excellent on electromagnetic conversion characteristic.Particularly, in patent documentation 5, instructed: although stipulated the amount of the sintering preventing agent of per unit surface area, but in order to prevent that particle is bonding, it is dispersed to improve, magnetic characteristic and the superficiality of raising magnetic recording media, need to contain the above sintering preventing agent of setting.
In order to improve the packing density of magnetic recording media, the quantity of the magnetic particle that needs increase per unit volume contains therefore must micronize.For example patent documentation 7,8 disclose use micronize as much as possible the technology of Magnaglo.As micronized method, generally be to seek micronize in the stage of raw material (precursor) in the past, this stage is used for by roasting, reduction synthesizing magnetic particle.If but micronized precursor were supplied with roasting, reduction, would occur more easily that sintering between particle, shape of particle burst apart, degradation problem under the axial ratio.Therefore, need to contain a large amount of sintering preventing agents in the precursor.
But because the rare earth element or Al, the Si that use as the sintering preventing agent are nonmagnetic, if therefore the ratio of the per unit volume of Magnaglo these " the non magnetic compositions " that comprise increases, saturation magnetization will reduce.Particularly with magnetic powder particles the time, need as mentioned above to increase the amount of sintering preventing agent, therefore have amount increase, the significantly reduced problem of saturation magnetization of the sintering preventing agent of per unit volume.In addition, patent documentation 9 put down in writing to magnetic particle implement the degassed processing of compression, by opening because of combination that sintering or particle interphase interaction cause, improving dispersed method.
On the other hand, if cause particle volume to diminish by micronize, general saturation magnetization reduces.As one of its reason, can exemplify: in order to keep the weatherability of Magnaglo, need to form at particle surface and have certain thickness oxide-film, if therefore micronize, the volume of metal part just relatively reduces.In order to improve the magnetic characteristic of metallic magnetic powder, the volume ratio that improves the metal part of bearing magnetic is effectively, formerly just is devoted to such research always.But this gimmick mainly is conceived to adjust the thickness of oxide-film.At this moment, there is because of relatively oxide-film attenuation the problem of easily following weatherability to reduce.
[patent documentation 1] Unexamined Patent 07-022224 communique
[patent documentation 2] Unexamined Patent 06-215360 communique
[patent documentation 3] Unexamined Patent 07-078331 communique
[patent documentation 4] Unexamined Patent 07-184629 communique
[patent documentation 5] JP 2003-296915 communique
[patent documentation 6] JP 2005-101582 communique
[patent documentation 7] JP 2003-242624 communique
[patent documentation 8] JP 2005-259929 communique
No. 3043785 communique of [patent documentation 9] patent
Summary of the invention
As mentioned above; seeking in the micronized situation of Magnaglo; because the addition of sintering preventing agent relatively increases; and easily become problem for the amount of the oxide-film of keeping weather resistance necessity relatively increases the harmful effect to magnetic characteristic that causes, adopt the addition that reduces the sintering preventing agent, make oxide-film attenuation etc. directly gimmick to address this problem be extremely difficult.
In addition, in order to improve the orientation of tape, must prevent sintering, improve dispersiveness.If but carrying out micronize, the surface area of magnetic powder increases, easy sintering becomes.Particularly, according to inventor's nearest research as can be known, even use such as patent documentation 5 disclosed gimmicks and suppress sintering between particle, although can get anti-sintering effect to a certain degree, especially namely be the simple amount that increases as the sintering preventing agent of the Magnaglo with the particle diameter below the 100nm of particulate, but also be difficult to prevent fully interparticle sintering.And, because sintering causes forming thick agglutination body, cause dispersed variation, also produce the problem of the orientation characteristic degradation of tape, increase because the amount that increases the sintering preventing agent causes non magnetic composition, because the amount of magnetization of the per unit volume of magnetic powder reduces, the problem that exists Br to reduce during tape.
Open in the method for agglutination body in the compression pressurization of passing through shown in patent documentation 9, have the problem that magnetic particle is damaged, magnetic characteristic worsens because magnetic particle being applied mechanical pressure.Particularly this tendency of the Magnaglo with the particle diameter below the 100nm as particulate is obvious, and therefore adopting as can be known such method is not very wise move.Namely, the Magnaglo with the particle diameter below the 100nm as particulate, from before empirical law recognize, be necessary to reduce the amount of nonmagnetic sintering preventing agent and improve dispersed, but reduce the sintering preventing agent promote particle each other sintering if particulate then this tendency become remarkable.Therefore, even be to be accompanied by micronize and the addition that increases the sintering preventing agent in the past, but do not have to adopt simply the addition that reduces the sintering preventing agent such can be described as desirable gimmick.
But; to prevent when the roasting or to be sintered to purpose during heat reduction; the sintering preventing agent is to be added in the front raw material of roasting; the effect because it has been through with in passing through the synthetic metallic magnetic powder of roasting or heat reduction; therefore think; if can not reduce the sintering preventing agent addition, remove " the non magnetic composition " that in metallic magnetic powder, contain from the sintering preventing agent, just might make the relative amount of the metal part of bearing magnetic than the reduction that increases, suppresses to be accompanied by micronized saturation magnetization when preventing sintering reaching.In addition, also thinking one of reason as magnetic head dirt (head dirty) in the application type magnetic recording media, is the impact from the composition of sintering preventing agent that exists at particle surface, considers that from this respect it also is effective removing this non magnetic composition.
And the sintering preventing agent is in the near surface segregation (segregate) of Magnaglo.Melt owing to causing the sintering preventing agent in the thermal conductance in roasting, when reduction, produce bonding (necking phenomenon necking) at the sintering preventing agent composition of each particle surface, magnetic particle forms agglutination body each other.Therefore, can consider by removing near surface the sintering preventing agent, untie necking phenomenon, improve aggegation between particle, improve thus the magnetic powder for the dispersiveness of adhesive.
But it is not necessarily easy only effectively to remove from the non magnetic composition of sintering preventing agent from the particle of metallic magnetic powder, and its gimmick is not also established.
The present invention is in view of this present situation, purpose provides from the particle of metallic magnetic powder and removes technology from the non magnetic composition of the sintering preventing agent of end effect, be provided at thus when keeping with the equal weatherability level of prior art, compare its saturation magnetization σ s (Am with particle volume
2/ kg) large, the metallic magnetic powder of the application type magnetic recording media that is suitable for high record density and the application type magnetic recording media that uses this metallic magnetic powder.
Above-mentioned purpose reaches with metallic magnetic powder by magnetic recording media, described magnetic recording media metallic magnetic powder is to comprise the metal magnetic that has take Fe or Fe and Co as main component mutually and the powder of the particle of oxide-film, and the long 10～50nm of the average major axis of this powder particle, the averaged particles volume that contains oxide-film are 5000nm
3Below, being used in (R+Al+Si)/(Fe+Co) atomic ratio that the value of the content (atom %) of each element that contains in the powder particle calculates is below 20%, and preferably the content of the above-mentioned non magnetic composition of the per unit surface area of powder is 40 μ mol/m
2Below.
Herein, so-called " atomic ratio (R+Al+Si)/(Fe+Co) is below 20% ", the meaning refers to the establishment of following (2) formula,
(R+Al+Si)/(Fe+Co)×100≤20……(2)
The content of this element that wherein, represents with atom % in the local substitution of each element mark.R is rare earth element (Y also treats as rare earth element).There is no need in a rare earth element, Al, Si all be included in.For the rare earth element that does not contain, substitution zero in (2) formula.
Rare earth element (Y also treats as rare earth element), Al and Si are called " non magnetic composition " herein.It is so-called that " content of the non magnetic composition of the per unit surface area of powder is 40 μ mol/m
2Below " looking like refers to the establishment of following (3) formula.
[total mole number of the R+Al+Si that every 1g powder contains] (μ mol/g)/[the BET specific area of powder] (m
2/ g)≤40 ... (3)
This metallic magnetic powder in the pore of this powder of measuring by mercury penetration method distributes, for example is below the 1.0mL/g in the cumulative volume of the pore in the zone that fine pore is grown up than the average major axis of this powder.To be somebody's turn to do in this manual " cumulative volume of the pore in the zone that fine pore is grown up than the average major axis of this powder " and be called " accumulation inter-particle voids ".
In addition, this metallic magnetic powder, for example, saturation magnetization σ s (Am
2/ kg) and contain the averaged particles volume V (nm of oxide-film
3) between the relation of following (1) formula set up,
σs≥0.0185V+58……(1)
And the reduced rate Δ σ s of the saturation magnetization when under the atmosphere of temperature 60 C, humidity 90% this metallic magnetic powder having been kept 1 time-of-week (168 hours) is that metallic magnetic powder below 15% becomes suitable object.
The reduced rate Δ σ s of saturation magnetization is the index of estimating the weatherability of Magnaglo, by the definition of following (4) formula,
Δσs(％)＝(σs(i)-σs(ii))/σs(i)×100……(4)
Wherein, σ s (i) is the saturation magnetization (Am before keeping in above-mentioned atmosphere
2/ kg), σ s (ii) is the saturation magnetization (Am that has kept in above-mentioned atmosphere after 168 hours
2/ kg).
Such metallic magnetic powder, above-mentioned than the metallic magnetic powder behind after the roasting of magnetic components or the further heat reduction for containing, can by and with complexing agent and reducing agent enforcement the processing of non magnetic composition stripping in liquid made.Be among the present invention, the manufacture method of magnetic recording media with metallic magnetic powder is provided, has following operation, for comprise the metal magnetic that has take Fe or Fe and Co as main component mutually, contain the metallic magnetic powder of the particle more than a kind of above-mentioned non magnetic composition, by added can and the liquid of the complexing agent of at least a formation complex compound of above-mentioned non magnetic composition in reducing agent is had an effect, make the operation (stripping treatment process) of non magnetic composition stripping in liquid in the powder particle.Preferably after above-mentioned stripping treatment process, and then adopt the operation (oxidation processes operation) that forms oxide-film on the surface of powder particle.
As complexing agent, for example can use a kind of in sodium tartrate and the natrium citricum or two kinds herein.In addition, as reducing agent, can use hydrazine (N
2H
2), lithium aluminium hydride reduction (LiAlH
4), sodium borohydride (NaBH
4) and more than a kind of derivative.
According to the present invention, when making metallic magnetic powder, do not reduce " addition " of the sintering preventing agent of interpolation, by adopting the such means of non magnetic composition stripping that from the metallic magnetic powder that obtains through roasting or heat reduction, make from the sintering preventing agent of finishing effect, can prevent particles sintering, increase the relative scale of the metallic element of bearing magnetic simultaneously.Therefore, metallic magnetic powder of the present invention has significantly suppressed to be accompanied by the reduction of micronized saturation magnetization, and particle volume is little, presents the saturation magnetization higher than existing metallic magnetic powder.By significantly removing the sintering preventing agent of particle surface, because of interparticle combination (necking phenomenon) collapse that the sintering preventing agent causes, the dispersed raising.And, even do not take the measure that makes oxide-film thin especially, also can suppress to be accompanied by the reduction of micronized saturation magnetization, therefore the evils that weatherability reduces do not occur yet.This present invention is the invention of making according to the requirement of the high record density that becomes recently more and more stricter on the application type magnetic recording media and weatherability raising (keeping the raising of the reliability of high saturation).
Description of drawings
Fig. 1 is that expression is for the metallic magnetic powder that obtains at each embodiment and comparative example, the figure of the relation of averaged particles volume V and saturation magnetization σ s.
Fig. 2 is the figure that distributes for the pore of the metallic magnetic powder of sample before the stripping 3 and embodiment 5 (with the longitudinal axis as cumulative volume).
Fig. 3 is the figure of the state of the metallic magnetic powder before and after the expression stripping of pattern ground is processed.
Embodiment
" metallic magnetic powder "
As the Magnaglo of object, be to comprise the metallic magnetic powder with the metal magnetic particle mutually take " Fe " or " Fe and Co " as main body in the present invention.That is be that the atomic ratio that " Fe " or " Fe and Co " occupies is more than 50% in the magnetic element (Fe, Co, Ni) that consists of the metal magnetic phase.And this powder has oxide-film, contain oxide-film and metal magnetic powder particle mutually all in the mol ratio of element of existence, take with respect to the ratio (hereinafter referred to as " Co/Fe atomic ratio ") of the Co of Fe as the material of 0～50at% as object.Herein, the Co/Fe atomic ratio represents with " Co content (at%)/Fe content (at%) * 100 ".The Co/Fe atomic ratio is 5～45at% more preferably, further preferred 10～40at%.Easily obtain stable magnetic characteristic in such scope, it is good that weatherability also becomes.Oxide-film is the oxide-film that detects ferriferous oxide, but also can have simultaneously the oxide of other element.
In manufacture process, add rare earth element (Y also treats as rare earth element), Al and Si etc. " non magnetic composition " as the sintering preventing agent, but metallic magnetic powder of the present invention is sought the stripping of these non magnetic compositions by method described later, and therefore (R+Al+Si)/(Fe+Co) atomic ratio is below the 20at%.That is, above-mentioned (2) formula is set up.Compared with former micronized metallic magnetic powder this moment, provides than the large powder of the saturation magnetization of particle volume.More preferably (R+Al+Si)/(Fe+Co) atomic ratio is below the 15at%, below the further preferred 13at%, or further below the preferred 12at%.
Consist of in the element of powder particle, except Fe, Co, Ni, rare earth element (Y also treats as rare earth element), Al, Si and O, such as the various elements that also can sneak into the alkaline-earth metal that adds as the sintering preventing agent etc.As the powder constituent of object, contain Fe, Co, Ni, rare earth element (Y also treats as rare earth element), Al, Si and O in the present invention, remainder is inevitable impurity.
In addition, preferably according to the permission content range of the surface area of powder regulation from the non magnetic composition of sintering preventing agent.Particularly, the content of the above-mentioned non magnetic composition of the per unit area of preferred powder is 40 μ mol/m
2Below.That is, the mode of the content of non magnetic composition above-mentioned to satisfy (3) formula is restricted.In addition, if non magnetic composition to contain quantitative change many, the saturation magnetization of metallic magnetic powder easily reduces, causes thus the C/N of the magnetic recording media deterioration that easily becomes.Particularly preferably be, during with containing element and be called " X composition " beyond Fe, Co, Ni, rare earth element (Y also treats as rare earth element), Al, Si and the O, the total amount of the rare earth element of the per unit surface area of powder, Al, Si and X composition is limited in 40 μ mol/m
2Below, more preferably 30 μ mol/m
2Below.
About the size of powder particle, take the long 10～50nm of average major axis and averaged particles volume as 5000nm
3Below, preferred 4500nm
3Following particle is object.If particle size is larger than it, be difficult to abundant high record density corresponding to tape.Alleged major axis is long in this invention, refers to the longest length in all diameters of particle picture in the particle of electron micrograph observation.On the other hand, the particle picture of observing by photo is in the oval or circular situation (ratio of the diameter (minor axis) of the diameter (major diameter) of long part and short part near 1～2 situation), and alleged major axis is long herein for the longest diameter conduct in section.
In addition, according to particle of the present invention, in order to improve interparticle necking phenomenon, take the accumulation inter-particle voids less than 1.0mL/g as feature.This accumulates inter-particle voids, is to be illustrated in during the pore of measuring by mercury penetration method distributes, and fine pore is than the value of the summation of pore volume in the long also large zone of average major axis.Namely, in fine pore than average major axis in the long also little zone, what measure as fine pore is the pore self of the particle that exists in the top layer of particle, relative therewith, and what measure in the zone of growing up than average major axis is expression because of particle coincidence or the space that produces of fusion each other.
Herein, " average major axis long " is on average from the long numerical value of major axis of each particle (at least 300) of above-mentioned transmission electron microscope determining image.
Therefore, at the fine pore particle that in the long also large zone Duo in the space than average major axis, interparticle necking phenomenon is many, and the possibility that forms agglutination body is high.Such aggegation, the deterioration of the filling in the time of may being related to medium (packing), and then be related to the characteristic degradation (the orientation characteristic degradations of the increase of corpuscular property noise, squareness ratio etc.) of magnetic recording media.Therefore the space is more few better, but according to the inventor's knowledge opinion, the accumulation inter-particle voids is advisable less than 1.0mL/g, preferably less than 0.9mL/g, more preferably less than 0.8mL/g.Although the accumulation inter-particle voids is more little more preferred, be difficult to remove fully space (even in the situation that each other simple overlapping also existence of particle), the accumulation inter-particle voids that therefore calculates is the value larger than 0mL/g.The accumulation inter-particle voids is affected by the shape of particle also.
As the shape of particle, can consider needle-like, spindle shape, flat needle-like, the various forms such as granular.Especially during flat needle-like, because each other laminated of particle do not produce the space, consists of ideally, therefore the space of waste is few, so be preferred.
As the magnetic characteristic of metallic magnetic powder of the present invention, with saturation magnetization σ s (Am
2/ kg) and contain the averaged particles volume V (nm of oxide-film
3) between the relation of following (1) formula set up as particularly preferred object.
σs≥0.0185V+58……(1)
Even to be the size of particle little also presents the powder of excellent saturation magnetization for this Magnaglo.
In addition simultaneously, preferably, the reduced rate Δ σ s of the saturation magnetization when keeping for 1 week under the atmosphere of temperature 60 C, humidity 90% is good weatherability properties such below 15%.
The metallic magnetic powder that possesses these characteristics, high as the practicality of high record density magnetic recording media.
" manufacture method of metallic magnetic powder "
The raw meal of sintering preventing agent has been added in roasting, can adopt the manufacture method of general metal magnetic powder before reduction phase.For example, by known method 250～700 ℃ roasting temperature contain Co and sintering preventing agent FeOOH, make it become α-Fe
2O
3Deng ferriferous oxide.By vapour phase reduction heat reduction this ferriferous oxide, obtain metallic magnetic powder take α-Fe as main component thereafter.Claim this metallic magnetic powder to be " intermediate products after the reduction ".In order to obtain metallic magnetic powder of the present invention, for the intermediate products after the above-mentioned reduction, be necessary to apply the processing (stripping treatment process) that makes from the non magnetic composition stripping of sintering preventing agent.After the stripping treatment process, by supplying with the processing (oxidation processes operation) that forms oxide-film, obtain metallic magnetic powder of the present invention.
[stripping treatment process]
Intermediate products as after the reduction that is used for supply stripping treatment process can use the surface to form the powder of oxide-film.But in order to improve the result of extraction from sintering preventing agent composition, preferably prepare not form the powder that oxide-film is processed.
As treatment fluid, prepare to have dissolved the solution of compound (complexing agent), this compound can with the rare earth element (Y also treats as rare earth element), at least a formation complex compound among Al, the Si that comprise in the intermediate products after reduction.As complexing agent, there is no need special restriction, chemicals, such as tartrate, citrate, malate, lactate etc. of usually using as complexing agent in electroless plating can easily obtain.The concentration of complexing agent is to be advisable about 0.01～10mol/L.Also can add the material with pH buffering effect as required, such as ammonium salt etc.The modulation for the treatment of fluid can be carried out under the temperature of near room temperature.
Add intermediate products after the above-mentioned reduction to this treatment fluid.The addition of powder, if too many, it is inhomogeneous that reaction might become, common every 1L treatment fluid adds about 1～100g, can obtain good result about preferred 5～50g.In order to keep the uniformity of reacting in the liquid, preferably stir or Forced Dispersion (such as ultrasonic wave dispersion etc.).
In treatment fluid, behind the powder Uniform Dispersion, in treatment fluid, add reducing agent.As reducing agent, use hydrazine (N
2H
2), lithium aluminium hydride reduction (LiAlH
4), sodium borohydride (NaBH
4) such known substance as strong reductant.If the stripping of magnetic element easily occurs, so not preferred in the reducing agent that the use reducing power is weak.If the concentration of reducing agent is too dense, the result of extraction of non magnetic composition reduces, so not preferred.If too rare, so the easy stripping of magnetic element is not preferred.The concentration of reducing agent can be adjusted in the scope of 0.01～10mol/L usually, more preferably 0.05～5mol/L, particularly preferably 0.1～5mol/L.After having added reducing agent, keep 10～50 ℃ of fluid temperatures, preferred 15～40 ℃ after, carry out leaching operation with 10～300min.Thus, the non magnetic composition of stripping in treatment fluid, the magnetic element amount is than relatively rising in magnetic powder particles.This reaction is preferably carried out under inert gas atmosphere.
Be illustrated in to Fig. 3 pattern stripping and process the state of front and back metallic magnetic powder.Supposition because the sintering preventing agent causes producing a lot of combinations (necking phenomenon) between particle, produces large space between particle and the particle before stripping is processed.In the situation that inter-particle voids exists is a lot, this inter-particle voids forms dead space (dead space), the tendency that is filled with deterioration of magnetic particle in magnetosphere.On the other hand, after stripping was processed, the dissolved result who removes of sintering preventing agent, these necking phenomena reduced, have guaranteed the independence of particle.Therefore, the minimizing of the noise when improving (quantity that is the magnetic particle of magnetosphere per unit volume existence increases), medium etc. is filled in expectation.
[oxidation processes operation]
To the metallic magnetic powder of the stripping treatment process that is through with, be implemented in the processing that forms oxide-film on the top layer of particle.Its method is not subjected to special restriction, can adopt existing general method.Namely, can adopt the damp process that drops into oxide in the liquid that in above-mentioned stripping is processed, uses to carry out, also can adopt dry process that the powder that separates from above-mentioned stripping treatment fluid, extract is carried out oxidation processes.But when adopting dry process to carry out, because powder sometimes forms unsure state, when processing, should be noted that.
" magnetic recording media "
The metallic magnetic powder of the present invention that obtains like this can use general method to use in the magnetosphere of multi-layer coated type magnetic recording media.
Multi-layer coated type magnetic recording media has nonmagnetic layer as lower floor at basilar memebrane, has the magnetosphere as the upper strata above it.Metallic magnetic powder of the present invention is mixed in the magnetospheric coating that is used to form the upper strata and uses.
The coating of upper strata, any one deck of lower floor can mix various materials, by using kneader and sand mill its method mixing, that disperse is in harmonious proportion in forming the such ratio of predetermined composition.Coating on the basad film of coating, when preferably moistening in lower floor with fast as far as possible speed coating upper strata magnetic, adopt wet mode of bumping wet (wet-on-wet) to carry out.
As the structure of multi-layer coated type magnetic recording media, for example can the following structure of illustration.
[basilar memebrane]
For example, can exemplify the resin molding of the polyesters, TPO, cellulosic triacetate, Merlon, polyamide, polyimides, polyamide-imides, polysulfones aromatic polyamides, aromatic polyamide etc. of PETG, PEN etc.
[nonmagnetic layer (lower floor) is used coating]
For example can exemplify and comprise nonmagnetic powder (alpha-ferric oxide: same and mining industry (strain) system, average major axis particle diameter 80nm) 85 mass parts, carbon black: 20 mass parts, aluminium oxide: 3 mass parts, vinyl chloride resin (Japanese ゼ オ Application (strain) preparing chloroethylene class adhesive: MR-110): 15 mass parts, ((strain) polyurethane resin processed spins to polyurethane resin in Japan: UR-8200): 15 mass parts methyl ethyl ketones: 190 mass parts, cyclohexanone: 80 mass parts, toluene: the non magnetic coating of the composition of 110 mass parts.
[magnetosphere (upper strata) is used coating]
For example can exemplify and comprise metallic magnetic powder of the present invention: 100 mass parts, carbon black: 5 mass parts, aluminium oxide: 3 mass parts, vinyl chloride resin (Japanese ゼ オ Application (strain) system: MR-110): 15 mass parts, polyurethane resin (top disclosed UR-8200): 15 mass parts, stearic acid: 1 mass parts, acetylacetone,2,4-pentanedione: 1 mass parts, methyl ethyl ketone: 190 mass parts, cyclohexanone: 80 mass parts, toluene: the magnetic coating of the composition of 110 mass parts.
[embodiment]
" comparative example 1 "
In the 5000mL beaker, add pure water 3000mL, maintain 40 ℃ with tempering machine, simultaneously add the solution 500mL that has mixed ferrous sulfate (special grade chemical) aqueous solution of cobaltous sulfate (special grade chemical) solution of 0.03mol/L and 0.15mol/L with 1: 4 mixed proportion to it.The granular sodium carbonate that directly to add relative Fe+Co carbonic acid be the amount of 3 equivalents, adjust temperature in the liquid on one side thereafter, make its be no more than ± 5 ℃, Yi Bian make suspension take ferric carbonate as main body.Its slaking after 1 hour 30 minutes, is added air with 50mL/min and adjusted, so that the oxygenation efficiency of Fe ion is 20%, make it form nucleus, be warming up to 65 ℃, and then with the logical purity oxygen of 50mL/min, continue oxidation 1 hour.Then begin slaking about 30 minutes from purity oxygen being changed into nitrogen.
, fluid temperature be cooled to 40 ℃, begin aluminum sulfate aqueous solution with 20 minutes 1.0 quality % of interpolation speed continuous adding of 5.0g/min as Al from temperature stabilization, FeOOH is grown up thereafter.And then continue to flow into purity oxygen with 50mL/min, finish oxidation.And the terminal point of oxidation is, the supernatant that minute takes a morsel uses the solution of six cyanogen Fe-laden acid potassium, confirm liquid color do not change after as terminal point.
Add aqueous sulfuric acid (containing 2.0 quality % as the Y) 300g of yittrium oxide in the liquid after oxidation finishes, like this Al by solid solution, obtain the powder of Y coating FeOOH from the teeth outwards.
Behind the filter cake by well-established law filtration, the above-mentioned FeOOH of washing, 130 ℃ of lower dryings, obtain the dry solid content of FeOOH.This solid content 10g is added in the batch can (bucket), adds water vapour as water with the boot speed of 1.0g/min, simultaneously in atmosphere 400 ℃ of lower roastings, obtain the ferrous oxide take alpha-ferric oxide (bloodstone) as main component.
This alpha-ferric oxide is dropped in the batch can that can ventilate, this batch can is packed in through (penetrate-type) reduction furnace, by leading to hydrogen (flow velocity: 40L/min) on one side, boot speed with 1.0g/min adds water vapour as water on one side, 400 ℃ lower roastings 30 minute implement reduce process on one side.Recovery time stops the supply of water vapour after finishing, and the programming rate with 10 ℃/min under hydrogen atmosphere is warming up to 600 ℃.Thereafter, add water vapour as water with the boot speed of 1.0g/min, the high temperature reduction that carried out simultaneously 60 minutes is processed, and makes metallic magnetic powder (iron-based alloy powder).The metallic magnetic powder in this stage is the powder of also not implementing to form the processing (oxidation processes) of oxide-film, and this metallic magnetic powder is equivalent to above-mentioned " intermediate products after the reduction ".
[oxidation processes]
In this comparative example, according to existing operation, for the intermediate products after the above-mentioned reduction, implement in order to form the oxidation processes of oxide-film.Particularly, from batch can, do not take out the intermediate products after the reduction, directly move to the oxidation processes operation.That is, thereafter, change furnace atmosphere into nitrogen from hydrogen, import nitrogen with the flow velocity of 50L/min, make in the stove temperature be down to 90 ℃ with 20 ℃/min of rate of temperature fall simultaneously.Oxide-film forms initial stage, in stove, add the gas that mixes with the mixed proportion of nitrogen 50L/min and purity oxygen 400mL/min, boot speed with 1.0g/min adds water vapour as water on one side, in the mixed atmosphere of water vapour, oxygen, nitrogen, form oxide-film on one side, cause the stage that heating is suppressed in the oxidation because of the surface, by the quantity delivered of slow increase air, the oxygen concentration in the atmosphere is risen, the flow of final purity oxygen becomes the addition of 2.0L/min.Roughly keep certain by the flow of adjusting nitrogen so that import the total amount of the gas in the stove this moment.Stabilization processes is implemented keeping under the general 90 ℃ atmosphere.
For the metallic magnetic powder that obtains like this (powder after the oxidation processes), powder characteristics and the composition studied as follows.
[mensuration of the long and short axial length of major axis]
For determined powder, use transmission electron microscope (the JEM-100CXMark-II type that NEC (strain) is made), carry out observation in the bright field with the accelerating voltage of 100kV.With multiple for example 58000 times this observation look like to take a picture photography, multiplication factor for example be extended to 9 times of length and width.For each sample, 300 monodispersed particles of random selection from a plurality of photograph images, long for major axis length and minor axis that each particle assay shows in its photograph image, its mean value represents the long and short axial length of the major axis of this sample.
[volume of particle]
Use the mean value of the long and short axial length of major axis that adopts said method mensuration, particle is similar to cylindrical shape, by the formula that represents below
(particle volume)=π * (major axis is long) * (minor axis long/2)
2
Obtain the volume of particle.
[specific area]
Use ユ ア サ イ オ ニ Network ス Quadrasork US processed, obtain by the BET method.
[crystallite size]
Use X-ray diffraction device (RAD-2C of Electric Co., Ltd of science system), obtain by following (5) formula.
Crystallite size=K λ/β cos θ ... (5)
Wherein, K:Sherrer constant 0.9, λ: Co-K alpha ray wavelength, the half width (radian) of the diffraction maximum of β: Fe (110) face, θ: the angle of diffraction (radian)
The scope of measurement range in 2 θ=45～60 ° scans to be calculated.Sweep speed is 5 °/minute in addition, and cumulative frequency is measured for 5 times.
[magnetic characteristic and weatherability]
Use the VSM device (VSM-7P) of Tohei Ind Co., Ltd.'s system, externally measure magnetic characteristic under the magnetic field 10kOe (795.8kA/m).The weatherability evaluation is to keep for 1 week in the constant temperature and humidity container of 60 ℃ of design temperatures, relative humidity 90%, measures the saturation magnetization σ s before and after keeping under this constant temperature and humidity, obtains according to above-mentioned (4) formula.
[composition analysis of powder particle]
The composition of powder particle is obtained by all particles that contains metal magnetic phase and oxide-film is carried out quality analysis.The NITROGEN/OXYGEN DETERMETER (TC-436 type) of the quantitative use LECOCorporation system of the flat natural pond of the quantitative use Industry Co., Ltd flat natural pond of the system automatic titration device (COMT IME-980) of the Japanese ジ ヤ one レ Le ア Star シ high-frequency inductive coupling plasma body processed apparatus for analyzing luminosity ICP of ユ Co., Ltd. (IRIS/AP) of quantitative use, the Fe of Co, Al and rare earth element (Y also treats as the rare earth element that contains), oxygen carries out.These quantitative results provide as quality %, therefore by suitably being transformed into atom % (at%), obtain Co/Fe atomic ratio, Al/ (Fe+Co) atomic ratio, Y/ (Fe+Co) atomic ratio, (R+Al+Si)/(Fe+Co) atomic ratio.In addition, in each comparative example, embodiment, because Si/ (Fe+Co) is measuring below the boundary, therefore (R+Al+Si)/(Fe+Co) atomic ratio equals (R+Al)/(Fe+Co) atomic ratio in these examples.
The results are shown in (the same in following comparative example) in the table 1.
" comparative example 2～24 "
The same manufacture method of method of employing and comparative example 1 expression forms and the oxidation processes condition by changing, and makes the sample of various compositions and particle size.
Composition and the magnetic characteristic of the sample that obtains like this are illustrated in the table 1.
" embodiment 1 "
The same manufacture method of method of employing and comparative example 1 expression is made " intermediate products after the reduction ".To be called " sample 1 before the stripping " to its sample of having implemented to obtain after " oxidation processes " of comparative example 1 record.Employing and comparative example 1 same method are obtained powder characteristics and the magnetic characteristic of the front sample 1 of stripping.Its result is illustrated in (same in the sample 2,3 before following stripping) in the table 2.
For the front sample 1 of stripping is implemented " oxidation processes " front metallic magnetic powder (i.e. " intermediate products after the reduction "), as following, implement stripping and process.
Prepare the treatment fluid that obtains in the following manner: be mixed with as the sodium tartrate of complexing agent with as the ammonium sulfate of buffer, make them be respectively 0.05mol/L and 0.1mol/L, use NH
3Adjust to pH=9.The metallic magnetic powder 10g of sample before the stripping 1 is put in the above-mentioned treatment fluid, and temperature remains on 30 ℃, and the sodium borohydride that then adds as reducing agent makes it become 0.3mol/L.It while stirring 30 minutes 30 ℃ of lower slakings, is obtained slurry.With this slurry Separation of Solid and Liquid, reclaim solid constituent and filtrate.
Filtration, washing, drying solid composition become dry product.Under according to the condition of " oxidation processes " shown in the above-mentioned comparative example 1, this dry product is implemented oxidation processes, obtain " metallic magnetic powder of embodiment 1 ".For " metallic magnetic powder of embodiment 1 ", and comparative example 1 is similarly studied powder characteristics and composition.
On the other hand, for filtrate, as the composition from the powder stripping, measure the concentration (ppm) of Fe, Co, Al, Y.
These the results are shown in (same in each following example) in the table 2." metallic magnetic powder of embodiment 1 " simply is designated as " embodiment 1 " (same for following embodiment) in table 2.In addition, " major axis is long " in the table 2 and " minor axis is long " refer to respectively " average major axis is long " and " average minor axis is long ".
Then, the tape of " sample 1 before the stripping ", " metallic magnetic powder of embodiment 1 " has been used in following making, and research is as the magnetic characteristic of medium.In addition, herein in order to confirm more brightly the effect of metallic magnetic powder, made the tape of the magnetosphere individual layer that nonmagnetic layer is not set.
[1] making of magnetic coating
Weighing Magnaglo 0.35g joins in the tank (pot) (internal diameter 45mm, dark 13mm).Placed 10 minutes with the state of opening lid.Then get 0.700mL carrier (vehicle) [Japan's spinning with micropipette, the mixed solution of vinyl chloride resin MR-110 (22 quality %), cyclohexanone (38.7 quality %), acetylacetone,2,4-pentanedione (0.3 quality %), BS (0.3 quality %), methyl ethyl ketone (38.7 quality %)], it is added in the above-mentioned tank.Add 10 of steel ball (2 φ) 30g, nylon beads (8 φ) at once in tank, closing cap left standstill 10 minutes.Then, this tank is placed centrifugal ball mill (FRITSH P-6), slowly improve rotating speed to 600rpm.Carry out 60 minutes dispersion.After centrifugal ball mill stops, taking out tank, use micropipette to add in advance with the methyl ethyl ketone that mixes at 1: 1 and the adjustment liquid 1.800mL of toluene.Again tank is placed centrifugal ball mill, disperseed 5 minutes with 600rpm, finish to disperse.
[2] making of tape
Be through with after the above-mentioned dispersion, open the lid of tank, take out nylon beads, coating is joined spreader (55 μ m) together with steel ball, on basilar memebrane (polyethylene film of eastern レ Co., Ltd. system, trade name 15C-B500, thickness 15 μ m), be coated with, after the coating, place at once the hub of a spool of the orientation device of 5.5kG, make its magnetic field orientating, then make its drying.
[3] evaluation test of tape characteristic
For the tape that obtains, use above-mentioned VSM, carry out the mensuration of coercivity H x, switch yard distribution SFD, squareness ratio SQ, OR.
The characteristic of the tape that table 3 expression obtains.
Then, for " sample 1 before the stripping " and " metallic magnetic powder of embodiment 1 ", as following, measure pore and distribute.
[pore measure of spread]
Use pore distribution porosity meter (Micromeritics instrument Corporation system, AutoPoreIV 9500 V1.05), measure by mercury penetration method.
Obtain above-mentioned " accumulation inter-particle voids " from the value that pore distributes and average major axis is long.With the value of " accumulation inter-particle voids " less than the metallic magnetic powder of 1.0mL/g be evaluated as zero (well), the above metallic magnetic powder of 1.0mL/g is evaluated as * (existing level), its result is documented in (identical in each following example) in the table 3 in the lump.
" embodiment 2 "
For the front sample 1 of above-mentioned stripping is implemented " oxidation processes " front metallic magnetic powder (i.e. " intermediate products after the reduction "), under following condition, implement dissolution test.
The treatment fluid that preparation obtains by following mode: be mixed with as the natrium citricum of complexing agent with as the ammonium sulfate of buffer, make them be respectively 0.05mol/L and 0.1mol/L, use NH
3Be adjusted to pH=9.The metallic magnetic powder 10g of sample before the stripping 1 is put in the above-mentioned treatment fluid, temperature is remained on 30 ℃, the hydrazine that then adds as reducing agent makes it become 4mol/L.It while stirring 30 minutes 30 ℃ of lower slakings, is obtained slurry.After the slurry Separation of Solid and Liquid that obtains, and embodiment 1 operates the characteristic of research metallic magnetic powder equally.
" embodiment 3 "
The same manufacture method of method shown in employing and the comparative example 1, " intermediate products after the reduction " of making and the front sample 1 different compositions of above-mentioned stripping.To be referred to as " sample 2 before the stripping " to its sample of having implemented to obtain after " oxidation processes " of comparative example 1 record.
For the front sample of above-mentioned stripping 2 is implemented " oxidation processes " front metallic magnetic powders (i.e. " intermediate products after the reduction "), with the same condition of embodiment 1 under implement the stripping processing.After the slurry Separation of Solid and Liquid that obtains, and embodiment 1 operates the characteristic of research metallic magnetic powder equally.
" embodiment 4 "
For the front sample of above-mentioned stripping 2 is implemented " oxidation processes " front metallic magnetic powders (i.e. " intermediate products after the reduction "), with the same condition of embodiment 2 under implement the stripping processing.After the slurry Separation of Solid and Liquid that obtains, and embodiment 1 operates the characteristic of research metallic magnetic powder equally.
" embodiment 5 "
The same manufacture method of method shown in employing and the comparative example 1, " intermediate products after the reduction " of making and the front sample 1 of above-mentioned stripping, 2 different compositions are referred to as " sample 3 before the stripping " to its sample of having implemented to obtain after " oxidation processes " of comparative example 1 record.
For the front sample 3 of above-mentioned stripping is implemented " oxidation processes " front metallic magnetic powder (i.e. " intermediate products after the reduction "), under following condition, implement stripping and process.
The treatment fluid that preparation obtains by following mode: be mixed with as the sodium tartrate of complexing agent with as the ammonium sulfate of buffer, make them be respectively 0.0028 (mol/L) and 0.0056 (mol/L).The metallic magnetic powder 10g of sample before the stripping 3 is put in the above-mentioned treatment fluid, temperature is remained on 30 ℃, then add the sodium borohydride as reducing agent, be 0.004mol/L, while it is stirred 30 minutes 30 ℃ of lower slakings, obtain slurry.After the slurry Separation of Solid and Liquid that obtains, and embodiment 1 operates the characteristic of research metallic magnetic powder equally.
Table 3
* 1) zero: less than 1.0mmL/g, *: more than the 1.0mmL/g
For as the metallic magnetic powder shown in the embodiment, but by the amount of stripping processing decrease from the non magnetic composition (Y, Al) of the element that adds as the sintering preventing agent, compare with Al and Y by the Fe of stripping processing stripping and the amount of Co, just little by little, confirm that therefore high efficiency selectively reduces the content of non magnetic composition.
Fig. 1 represents the relation of averaged particles volume V and saturation magnetization σ s.As can be known, the metallic magnetic powder of the present invention that obtains in each embodiment is processed by supplying with stripping, has satisfied (1) formula, compares with the metallic magnetic powder of comparative example, although particle volume is little, saturation magnetization σ s has obtained very big improvement.That is, confirmed to obtain the metallic magnetic powder that the improved magnetic recording media of relation of volume and magnetic characteristic is used by the present invention.Also being equal or higher with existing level for weatherability Δ σ s, is good.
As shown in table 3, can find out the powder of each embodiment that the stripping that is through with is processed, its accumulation inter-particle voids is reduced to less than 1.0mL/g, and what follow with it is the remarkable improvement of magnetic characteristic.Can think that this is because interparticle necking phenomenon is eliminated significantly, the orientation characteristic in the medium improves and the result that causes.
Fig. 2 be illustration for stripping before the metallic magnetic powder of sample 3 and embodiment 5, the figure that pore distributes (with the longitudinal axis as cumulative volume).
Claims (9)
1. magnetic recording media metallic magnetic powder, be to comprise the metal magnetic that has take Fe or Fe and Co as main component mutually and the powder of the particle of oxide-film, the averaged particles volume that the average major axis length of this powder particle is 10～50nm, contain oxide-film is 5000nm
3Below, (R+Al+Si)/(Fe+Co) atomic ratio that the value of the content of each element that use contains in powder particle is calculated is below 20%, wherein R is the rare earth element that comprises Y, the unit of the content of described each element is atom %, it is characterized in that, the saturation magnetization σ s of described metallic magnetic powder and contain the relation that satisfies following (1) formula between the averaged particles volume V of oxide-film, wherein the unit of saturation magnetization σ s is Am
2/ kg, the unit of averaged particles volume V is nm
3,
σs≥0.0185V+58……(1)，
The reduced rate Δ σ s of the saturation magnetization when wherein, this powder being kept for 1 week under the atmosphere of temperature 60 C, humidity 90% is below 15%.
2. magnetic recording media metallic magnetic powder according to claim 1, the total amount of the rare earth element that comprises Y, Al and the Si that wherein in powder particle, comprises, the per unit surface area of powder is 40 μ mol/m relatively
2Below.
3. according to claim 1 or 2 described magnetic recording media metallic magnetic powders, wherein, in the pore of this powder of measuring by mercury penetration method distributed, the cumulative volume of the pore in the zone that fine pore is grown up than the average major axis of this powder was below the 1.0mL/g.
4. the described magnetic recording media of claim 1～3 any one is with the manufacture method of metallic magnetic powder, and it has following operation, namely for comprising:
Have take Fe or Fe and Co as main component metal magnetic mutually,
The metallic magnetic powder of particle that contains the non magnetic composition more than a kind of the rare earth element, Al and the Si that comprise Y, by added can and the liquid of the complexing agent of at least a formation complex compound of above-mentioned non magnetic composition in reducing agent is had an effect, make the stripping treatment process of the non magnetic composition stripping in liquid in the powder particle.
5. magnetic recording media according to claim 4 wherein, as complexing agent, uses sodium tartrate and more than a kind of natrium citricum with the manufacture method of metallic magnetic powder.
According to claim 4 or 5 described magnetic recording medias with the manufacture method of metallic magnetic powders, wherein, as reducing agent, use hydrazine (N
2H
2), lithium aluminium hydride reduction (LiAlH
4), sodium borohydride (NaBH
4) and more than a kind of derivative.
According to claim 4 or 5 described magnetic recording medias with the manufacture method of metallic magnetic powders, wherein, after above-mentioned stripping treatment process, further have the oxidation processes operation that forms oxide-film on the surface of powder particle.
8. magnetic recording media according to claim 6 wherein, after above-mentioned stripping treatment process, further has the oxidation processes operation that forms oxide-film on the surface of powder particle with the manufacture method of metallic magnetic powder.
9. right to use requires the magnetic recording media of the described metallic magnetic powder of 1～3 any one.
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| JP2006086906 | 2006-03-28 | ||
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| JP2006261531 | 2006-09-26 | ||
| JP2006261531A JP4758858B2 (en) | 2006-03-28 | 2006-09-26 | Metallic magnetic powder for magnetic recording medium and method for producing the same |
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| US20110123830A1 (en) * | 2008-08-05 | 2011-05-26 | Dowa Electronics Materials Co., Ltd. | Metallic magnetic powder for magnetic recording and process for producing the metallic magnetic powder |
| EP2555194A4 (en) * | 2010-03-31 | 2016-01-27 | Dowa Electronics Materials Co | Metallic magnetic powder, process for producing same, magnetic coating composition, and magnetic recording medium |
| JP5781276B2 (en) * | 2010-05-12 | 2015-09-16 | ジ・アリゾナ・ボード・オブ・リージェンツ・オン・ビハーフ・オブ・ザ・ユニバーシティ・オブ・アリゾナＴｈｅ Ａｒｉｚｏｎａ Ｂｏａｒｄ Ｏｆ Ｒｅｇｅｎｔｓ Ｏｎ Ｂｅｈａｌｆ Ｏｆ Ｔｈｅ Ｕｎｉｖｅｒｓｉｔｙ Ｏｆ Ａｒｉｚｏｎａ | Method for producing metal magnetic powder |
| WO2015152048A1 (en) * | 2014-03-31 | 2015-10-08 | Ｄｏｗａエレクトロニクス株式会社 | Fe-co alloy powder, manufacturing method therefor, antenna, inductor, and emi filter |
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| JP2002123926A (en) * | 2000-10-16 | 2002-04-26 | Sony Corp | Magnetic metal powder, method for producing the same and magnetic recording medium |
| JP2005251351A (en) * | 2004-03-08 | 2005-09-15 | Fuji Photo Film Co Ltd | Manufacturing method of magnetic recording medium and ferromagnetic metal powder |
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| EP1637499A1 (en) * | 2003-05-29 | 2006-03-22 | Riken | Metal nanoparticle with support, continuous metal nanoparticle body, and methods for producing these |
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