EP0000749B1 - Verfahren zur Herstellung von nadelförmigen, ferrimagnetischen Eisenoxiden und deren Verwendung - Google Patents

Verfahren zur Herstellung von nadelförmigen, ferrimagnetischen Eisenoxiden und deren Verwendung Download PDF

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Publication number
EP0000749B1
EP0000749B1 EP78100535A EP78100535A EP0000749B1 EP 0000749 B1 EP0000749 B1 EP 0000749B1 EP 78100535 A EP78100535 A EP 78100535A EP 78100535 A EP78100535 A EP 78100535A EP 0000749 B1 EP0000749 B1 EP 0000749B1
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EP
European Patent Office
Prior art keywords
iron
oxide
iii
acicular
magnetic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
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EP78100535A
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German (de)
English (en)
French (fr)
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EP0000749A1 (de
Inventor
Rudolf Dr. Brodt
Helmut Dr. Jakusch
Eberhard Dr. Koester
Werner Dr. Loeser
Manfred Dr. Ohlinger
Wilhelm Dr. Sarnecki
Werner Dr. Steck
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BASF SE
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BASF SE
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Publication of EP0000749A1 publication Critical patent/EP0000749A1/de
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Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
    • G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
    • G11B5/70642—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides
    • G11B5/70652—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides gamma - Fe2 O3
    • G11B5/70663—Preparation processes specially adapted therefor, e.g. using stabilising agents
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G49/00—Compounds of iron
    • C01G49/02—Oxides; Hydroxides
    • C01G49/06—Ferric oxide [Fe2O3]
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
    • G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
    • G11B5/70642—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides
    • G11B5/70647—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides with a skin
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
    • G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
    • G11B5/70642—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides
    • G11B5/70652—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides gamma - Fe2 O3
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/54—Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/42—Magnetic properties

Definitions

  • the invention relates to a method for producing acicular ferrimagnetic iron oxides by dewatering acicular iron (III) oxide hydroxides to acicular iron (III) oxides, then reducing these iron (III) oxides at temperatures between 300 and 650 ° C by means of organic compounds which are decomposable in this temperature range Oxidation of the resulting products with oxygen-containing gases at 200 to 500 ° C and their use for the production of magnetic recording media.
  • GR-PS 675 260 already describes a process for the production of gamma-iron (III) oxide, in which acicular iron oxide hydroxide (goethite) is dewatered to ⁇ -iron (III) oxide, in a reducing atmosphere at more than 300 ° C is converted to magnetite and oxidized in air at temperatures below 450 ° C to acicular gamma iron (III) oxide.
  • this process was varied several times in its individual stages, and was also modified by changing the starting materials.
  • suitable magnetic iron oxides were obtained in the manner disclosed in DE-PS 801 352, namely by treating non-magnetic iron oxides with the salts of short-chain carboxylic acids and subsequent heating.
  • the magnetite obtained afterwards can also be converted into gamma-iron (III) oxide by oxidation at 200 to 400 ° C.
  • 2,900,236 specifies all of the corresponding organic substances as being usable with particular mention of wax, starch and oil
  • DE-AS 12 03 656 describes salts of soluble soaps precipitated on iron oxide
  • DE-OS 20 64 804 both higher hydrocarbons, higher alcohols and amines, higher fatty acids and their salts as well as oils, fats and waxes, in DD-PS 91 017 also long-chain carboxylic acids or their salts
  • DE-AS 17 71 327 aliphatic monocarboxylic acids with 8 to 24 carbon atoms optionally mixed with morpholine 'and in JP-OS 80 499/1975 organic compounds, such as Ethanol, containing inert gases as a reducing agent for the extraction of magnetite from non-magnetic iron oxides.
  • heating is carried out partly in the absence of air, the reaction remaining at the magnetite stage or in the presence of air, as a result of which the magnetite is immediately oxidized to gamma
  • the starting materials for this conversion of the iron oxides by means of organic substances were predominantly the corresponding a-modifications, such as a-FeOOH or ⁇ -Fe 2 O 3 , but 8-FeOOH (DE-AS 1203656) and y-Fe00H (DE- OS 22 12 435) used successfully.
  • the invention was therefore based on the object of improving the known acicular ferrimagnetic iron oxides and of eliminating the disadvantages to date.
  • acicular ferrimagnetic iron oxides are formed by dewatering acicular iron (III) oxide hydroxides to acicular iron (III) oxides, then reducing these iron (III) oxides at temperatures between 300 and 650 ° C by means of organic compounds which are decomposed in this temperature range and Allow oxidation of the reduction product with oxygen-containing gases to be obtained at 200 to 500 ° C with the properties required by the task if the acicular iron (III) oxide hydroxide used consists of a mixture of goethite and lepidocrocite with a lepidocrocite content of at least 60% and up to 98% and is dewatered at temperatures from 200 to 700 ° C.
  • the acicular iron (III) oxyhydroxides of the mixture have a length to thickness ratio of at least 10 and are dewatered at 300 to 650 ° C.
  • the iron (III) oxyhydroxides composed of goethite and lepidocrocite preferably consist of 70 to 98% of lepidocrocite.
  • the batches used for the process according to the invention can be prepared under suitable reaction conditions from iron (II) salt solutions with alkalis with simultaneous oxidation. It has proven to be particularly expedient to use iron (III) oxide hydrate seeds from an aqueous iron (II) chloride solution using alkalis, such as alkali hydroxide or ammonia, at temperatures between 10 and 32 ° C. and vigorous stirring to produce fine air bubbles To form amount of 25 to 60 mole percent of the iron used, from which then at a temperature between 25 and 70 ° C and at a pH adjusted by adding further amounts of alkali from 4.0 to 5.8 with intensive air distribution through growth The end product is created.
  • iron (III) oxide hydrate seeds from an aqueous iron (II) chloride solution using alkalis, such as alkali hydroxide or ammonia
  • the solids content of iron (III) oxide hydroxide in the aqueous suspension should be between 10 and 50 g / l, preferably 15 to 45 g / l. After filtering off and washing out the precipitate, the iron (III) oxide hydrate mixture thus obtained is dried at 60 to 200 ° C.
  • Stable crystal needles of the goethite-lepikrokite mixture with at least 60% and up to 98% lepidocrocite, which have almost no dendritic branches, can be obtained by the procedure described by way of example.
  • These acicular goethite-lepicrokite mixtures have an average particle size of 0.2 to 1.5, usually 0.3 to 1.2 ⁇ m.
  • the length-to-thickness ratio is generally at least 10, mostly 12 to 40.
  • the surface area measured according to BET is between 18 and 70 m 2 / g.
  • a goethite-lepidocrocite mixture characterized in this way is dewatered according to the invention at temperatures between 200 and 700.degree. C., preferably between 300 and 650.degree. C. and in particular between 450 and 600.degree Improve values for coercive field strength and remanence of the end products available from them.
  • the dewatering can be carried out both in air and in an inert gas atmosphere.
  • the product present after the dewatering step is converted in a manner known per se with largely ash- and tar-free decomposable organic substances at temperatures between 300 and 650 ° C. to acicular ferrimagnetic iron oxides.
  • the dewatered goethite-lepidocrocite mixture is mechanically mixed with the solid or liquid organic substance or coated in a suitable solution or suspension of the substance and then heated to temperatures of 300 to 650 ° C. under inert gas.
  • the method can be carried out by means of gaseous organic substances which are added to the inert gas.
  • Organic compounds which can be used in the process according to the invention are all compounds which are stated to be suitable according to the prior art, provided they can be added at temperatures between 300 and 650 ° C. Expediently, higher fatty acids, their derivatives, glycerin, inert gas / alcohol vapor mixtures and also methane are used for this purpose.
  • the conversion of the dewatered goethite-lepidocrocite mixture to the acicular magnetite is complete after about 1 to 120 minutes.
  • the acicular magnetite obtained after this reduction reaction is usually oxidized to gamma-iron (III) oxide, advantageously by passing air or adding oxygen. Temperatures from 200 to 500 ° C.
  • the acicular ferrimagnetic iron oxides produced according to the invention show unexpectedly advantageous properties when used as magnetic pigments for the production of magnetogram carriers.
  • the gamma-iron (III) oxide is dispersed in polymeric binders.
  • binders such as homopolymers and copolymers of polyvinyl derivatives, polyurethanes, polyesters and the like.
  • the binders are used in solutions in suitable organic solvents, which may optionally contain further additives.
  • the magnetic layers are applied to rigid or flexible supports such as plates, foils and cards.
  • the acicular ferrimagnetic iron oxides produced according to the invention differ significantly from the known gamma-iron (III) oxides by their more uniform needle shape, since agglomeration is avoided by sintering together their improved crystallinity and the higher coercive field strength and remanence, which can surprisingly be achieved in the process according to the invention. These improvements in the magnetic material are also very noticeable in the magnetic tapes made therefrom.
  • the coercive field strength (H e ) is expressed in [kA / m]
  • the specific remanence (M, / p) and the specific magnetization (M m / p) are given in [nT cm 3 / g].
  • the suspension is washed on a suction filter with water until the filtrate is chloride-free and then dried at 130 ° C. in a drying cabinet.
  • the resulting iron oxide hydroxide is a mixture of 94% lepidocrocite and 6% goethite, has a length-to-thickness ratio of 31 and a BET specific surface area of 34.7 m 2 / g.
  • This goethite-lepidocrocite mixture is heated in air for one hour at 490 ° C.
  • the resulting product is now mixed with 2% by weight of stearic acid, divided into two identical samples 1 A and 1 B and converted to magnetite under nitrogen under the conditions specified in Table 1 and oxidized to gamma-iron (III) oxide in air.
  • the magnetic properties are also shown in Table 1.
  • iron (III) oxide hydroxide mixtures with a lepidocrocite fraction of 72% with a BET specific surface area of 33.2 m 2 / g are produced.
  • These goethite-lepidocrocite mixtures are each dewatered in air at the temperatures given in Table 2 for one hour, then reduced to magnetite at 300 ° C. while passing over a nitrogen / methanol vapor mixture and then in air at 400 ° C. to the gamma Oxidized iron (III) oxide.
  • the nitrogen-methanol mixture is formed when nitrogen is passed through in an amount of 50 l per hour through a container heated to 105 ° C., to which methanol is metered.
  • the resulting magnetic values of the tests are also shown in Table 2.
  • Table 5 lists samples which were dewatered in 30 minutes at the lower dewatering temperature of 4 ° C. and then converted to ⁇ -Fe 2 O 3 .
  • the germ suspension was heated to 33 ° C. in 20 minutes.
  • the amount of air was then increased to 8 m 3 / h and the pH was adjusted to 5.5 by adding aqueous sodium hydroxide solution. and regulated to this value until the end of the reaction.
  • the mixture was simultaneously heated to 38 to 39 ° C. in 30 minutes and this temperature was maintained until the end of the growth reaction.
  • the oxidation was complete after 1 hour and 40 minutes. After filtration through a filter press, the product is washed with water until the filtrate is chloride-free and then dried at 110 ° C. in a drying cabinet.
  • the resulting iron (III) oxide hydrate is a mixture of 92% lepidocrocite and 8% goethite, has a length-to-thickness ratio of 16 and a BET specific surface area of 23.3 m2 / g .
  • Magnetic pigment dispersions and then magnetic tapes are produced from the two gamma-iron (III) oxide samples H and J.
  • the electroacoustic measurement is carried out according to DIN 45 512, part 11.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Dermatology (AREA)
  • General Health & Medical Sciences (AREA)
  • Hard Magnetic Materials (AREA)
  • Compounds Of Iron (AREA)
EP78100535A 1977-08-05 1978-07-28 Verfahren zur Herstellung von nadelförmigen, ferrimagnetischen Eisenoxiden und deren Verwendung Expired EP0000749B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2735316A DE2735316C3 (de) 1977-08-05 1977-08-05 Verfahren zur Herstellung von nadeiförmigen, ferrimagnetischen Eisenoxiden
DE2735316 1977-08-05

Publications (2)

Publication Number Publication Date
EP0000749A1 EP0000749A1 (de) 1979-02-21
EP0000749B1 true EP0000749B1 (de) 1980-07-23

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Application Number Title Priority Date Filing Date
EP78100535A Expired EP0000749B1 (de) 1977-08-05 1978-07-28 Verfahren zur Herstellung von nadelförmigen, ferrimagnetischen Eisenoxiden und deren Verwendung

Country Status (4)

Country Link
US (1) US4213959A (enrdf_load_stackoverflow)
EP (1) EP0000749B1 (enrdf_load_stackoverflow)
JP (1) JPS5428299A (enrdf_load_stackoverflow)
DE (2) DE2735316C3 (enrdf_load_stackoverflow)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2805405A1 (de) * 1978-02-09 1979-08-16 Basf Ag Verfahren zur herstellung von nadelfoermigen, ferrimagnetischen eisenoxiden
DE2805621A1 (de) * 1978-02-10 1979-08-23 Basf Ag Verfahren zur herstellung von nadelfoermigen, ferrimagnetischen eisenoxiden
GB2020278B (en) * 1978-05-03 1983-02-23 Nippon Shinyaku Co Ltd Moranoline dervitives
DE3019764A1 (de) * 1980-05-23 1981-12-03 Basf Ag, 6700 Ludwigshafen Verfahren zur herstellung von synthetischem lepidokrokit
DE3143870A1 (de) * 1981-11-05 1983-05-11 Basf Ag, 6700 Ludwigshafen Verfahren zur herstellung von nadelfoermigen, ferrimagnetischen eisenoxiden
JPS58199725A (ja) * 1982-05-12 1983-11-21 Fuji Photo Film Co Ltd 強磁性酸化鉄の製造方法
DE3224325A1 (de) * 1982-06-30 1984-01-05 Basf Ag, 6700 Ludwigshafen Verfahren zur herstellung von nadelfoermigen, ferrimagnetischen eisenoxiden
JPS61106408A (ja) * 1984-10-25 1986-05-24 Daikin Ind Ltd 炭化鉄を含有する針状粒子の製造法
US5069216A (en) * 1986-07-03 1991-12-03 Advanced Magnetics Inc. Silanized biodegradable super paramagnetic metal oxides as contrast agents for imaging the gastrointestinal tract
US5219554A (en) * 1986-07-03 1993-06-15 Advanced Magnetics, Inc. Hydrated biodegradable superparamagnetic metal oxides
EP0604849B1 (en) * 1992-12-29 1996-10-16 Ishihara Sangyo Kaisha, Ltd. Cobalt-containing magnetic iron oxide and process for producing the same
US5814164A (en) * 1994-11-09 1998-09-29 American Scientific Materials Technologies L.P. Thin-walled, monolithic iron oxide structures made from steels, and methods for manufacturing such structures
US6461562B1 (en) 1999-02-17 2002-10-08 American Scientific Materials Technologies, Lp Methods of making sintered metal oxide articles
JP7132901B2 (ja) 2019-10-01 2022-09-07 株式会社Soken 電力変換装置
CN115676898B (zh) * 2022-10-31 2024-05-07 昆明理工大学 一种一步碳热还原制备Fe3O4的方法

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1138750B (de) * 1950-05-26 1962-10-31 Basf Ag Verfahren zur Herstellung magnetisierbarer Eisenoxyde
US2900236A (en) * 1955-08-03 1959-08-18 Audio Devices Inc Production of ferromagnetic iron oxide
US3082067A (en) * 1959-04-28 1963-03-19 Bayer Ag Process for the production of isometric ferromagnetic gamma-ferric oxide
US3117933A (en) * 1959-06-12 1964-01-14 Bayer Ag Process for the production of needleshaped, cobalt-containing gamma-ferric oxide crystalline particles
GB1392196A (en) * 1971-03-17 1975-04-30 Pfizer Synthetic gamma ferric oxide
JPS5016859B2 (enrdf_load_stackoverflow) * 1971-09-30 1975-06-17
JPS5327719B2 (enrdf_load_stackoverflow) * 1972-05-23 1978-08-10
JPS5241758B2 (enrdf_load_stackoverflow) * 1972-09-01 1977-10-20
JPS5719056B2 (enrdf_load_stackoverflow) * 1974-04-08 1982-04-20
JPS5437680B2 (enrdf_load_stackoverflow) * 1975-03-22 1979-11-16

Also Published As

Publication number Publication date
DE2735316B2 (de) 1980-04-30
DE2735316C3 (de) 1981-01-29
EP0000749A1 (de) 1979-02-21
US4213959A (en) 1980-07-22
JPS6140602B2 (enrdf_load_stackoverflow) 1986-09-10
DE2860071D1 (en) 1980-11-13
JPS5428299A (en) 1979-03-02
DE2735316A1 (de) 1979-02-08

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