CA2026120A1 - Iron oxide red and iron oxide brown microgranulates, a process for their preparation and their use - Google Patents
Iron oxide red and iron oxide brown microgranulates, a process for their preparation and their useInfo
- Publication number
- CA2026120A1 CA2026120A1 CA002026120A CA2026120A CA2026120A1 CA 2026120 A1 CA2026120 A1 CA 2026120A1 CA 002026120 A CA002026120 A CA 002026120A CA 2026120 A CA2026120 A CA 2026120A CA 2026120 A1 CA2026120 A1 CA 2026120A1
- Authority
- CA
- Canada
- Prior art keywords
- iron oxide
- microgranulates
- process according
- carried out
- tempering
- 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.)
- Abandoned
Links
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 title claims abstract description 100
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000001058 brown pigment Substances 0.000 claims abstract description 12
- 239000007921 spray Substances 0.000 claims abstract description 11
- 238000001035 drying Methods 0.000 claims abstract description 9
- 239000007900 aqueous suspension Substances 0.000 claims abstract description 6
- 238000010438 heat treatment Methods 0.000 claims abstract description 5
- 239000000049 pigment Substances 0.000 claims description 15
- 239000001054 red pigment Substances 0.000 claims description 11
- 238000005496 tempering Methods 0.000 claims description 11
- 239000008187 granular material Substances 0.000 claims description 10
- 230000001590 oxidative effect Effects 0.000 claims description 8
- 239000000843 powder Substances 0.000 claims description 6
- 239000011230 binding agent Substances 0.000 claims description 4
- LQNUZADURLCDLV-UHFFFAOYSA-N nitrobenzene Chemical compound [O-][N+](=O)C1=CC=CC=C1 LQNUZADURLCDLV-UHFFFAOYSA-N 0.000 claims description 4
- 238000001556 precipitation Methods 0.000 claims description 4
- 238000000889 atomisation Methods 0.000 claims description 3
- 239000012065 filter cake Substances 0.000 claims description 3
- 239000004566 building material Substances 0.000 claims description 2
- 239000004922 lacquer Substances 0.000 claims description 2
- 239000000123 paper Substances 0.000 claims description 2
- 239000004033 plastic Substances 0.000 claims description 2
- 229920003023 plastic Polymers 0.000 claims description 2
- 238000011946 reduction process Methods 0.000 claims description 2
- 230000015572 biosynthetic process Effects 0.000 claims 4
- 238000000227 grinding Methods 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- 238000000137 annealing Methods 0.000 description 7
- 239000000725 suspension Substances 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 239000000428 dust Substances 0.000 description 4
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical class [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 3
- 229910052598 goethite Inorganic materials 0.000 description 3
- AEIXRCIKZIZYPM-UHFFFAOYSA-M hydroxy(oxo)iron Chemical compound [O][Fe]O AEIXRCIKZIZYPM-UHFFFAOYSA-M 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- 239000001052 yellow pigment Substances 0.000 description 3
- 238000001354 calcination Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910052595 hematite Inorganic materials 0.000 description 2
- 239000013067 intermediate product Substances 0.000 description 2
- 239000001034 iron oxide pigment Substances 0.000 description 2
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229920000058 polyacrylate Polymers 0.000 description 2
- 239000012266 salt solution Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- 229910002588 FeOOH Inorganic materials 0.000 description 1
- 238000006887 Ullmann reaction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000004645 aluminates Chemical class 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- -1 aromatic nitro compounds Chemical class 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 238000010410 dusting Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- LDHBWEYLDHLIBQ-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide;hydrate Chemical compound O.[OH-].[O-2].[Fe+3] LDHBWEYLDHLIBQ-UHFFFAOYSA-M 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005360 mashing Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 235000013379 molasses Nutrition 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000006259 organic additive Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical class C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 229910052596 spinel Inorganic materials 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
- D21H17/675—Oxides, hydroxides or carbonates
-
- 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]
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
- C04B14/30—Oxides other than silica
- C04B14/308—Iron oxide
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/20—Oxides; Hydroxides
- C08K3/22—Oxides; Hydroxides of metals
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/22—Compounds of iron
- C09C1/24—Oxides of iron
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
- C09C3/04—Physical treatment, e.g. grinding, treatment with ultrasonic vibrations
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/40—Additives
- C09D7/60—Additives non-macromolecular
- C09D7/61—Additives non-macromolecular inorganic
- C09D7/62—Additives non-macromolecular inorganic modified by treatment with other compounds
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/40—Additives
- C09D7/66—Additives characterised by particle size
- C09D7/69—Particle size larger than 1000 nm
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Ceramic Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Civil Engineering (AREA)
- Nanotechnology (AREA)
- Structural Engineering (AREA)
- Compounds Of Iron (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
- Paper (AREA)
Abstract
Iron Oxide Red and Iron Oxide Brown Microgranulates, a Process for their Preparation and their Use A B S T R A C T
A process for the preparation of iron oxide red or iron oxide brown pigment microgranulates is dis-closed wherein aqueous suspensions comprising iron oxide yellow or iron oxide black are subjected to spray granulating drying and the microgranulates thus obtained, which have diameters of from 20 to 600µm, are tempered by heating at temperatures of from 200 °C
to 1000 °C.
Le A 27 208
A process for the preparation of iron oxide red or iron oxide brown pigment microgranulates is dis-closed wherein aqueous suspensions comprising iron oxide yellow or iron oxide black are subjected to spray granulating drying and the microgranulates thus obtained, which have diameters of from 20 to 600µm, are tempered by heating at temperatures of from 200 °C
to 1000 °C.
Le A 27 208
Description
~v ~ ~
Iron Oxide Red and Iron Oxide Brown Microgranulates, a Process for their Preparation and their Use This invention relates to microgranulates of iron oxide red or iron oxide brown pigments, to a process for their preparation and to their use.
Iron oxide red pigments consist of finely divided haematite with a corundum struc:ture. Iron oxide brown pigments are generally composed of mixtures of haematite (iron oxide red) with magnetite (iron oxide black) and goethite (iron oxide yellow). They may also consist of a homogeneous product of maghaemite which crystallizes in the spinel lattice. ~oth iron oxide red and iron oxide brown pigments are chemically Fe2O3. Whereas iron oxide red is known as a-Fe2O3, the uniform iron oxide brown may be termed y-Fe203 (Ullmanns Encyklopadie der tech. Chemie, published by Verlag Chemie GmbH, Weinheim 1979, 4th Edition, Volume 18, pages 600 to 604).
Iron oxide red pigments may be prepared by various methods.
One method fre~uently employed consists of annealing iron LeA 27 208 2~v~
oxide black or iron oxide yellow in an oxidizing atmosphere at temperatures in the region of 800C. Homogeneous iron oxide brown is obtained by the same method ~ut at lower temperatures of about 200 to 600C, the exact shade obtained varying according to the temperature employed.
Iron oxide yellow pigments are normally obtained by the precipitation process in which iron (II) salts are reacted with alkalis under oxidizing conditions, in most cases by gassing with air, and selectively at an acid or a strongly alkaline pH to be converted into goethite (a-FeOOH). In another process, iron(II) salt solutions which have previously been oxidized by air are hydrolysed in the presence of metallic iron (Penniman process).
Iron oxide black pigments consisting of Fe3O4 may also be obtained by precipitation from iron(II) salt solutions with introduction of air, the process being carried out close to the neutral point. The black pigment may also be prepared by the reduction of aromatic nitro compounds to the corresponding amines with metallic iron.
In the processes mentioned above, the pigments are obtained as intermediate products in the form of aqueous suspensions which are filtered and washed. The final step of the process to the finished pigment is carried out by drying the filter cake obtained, followed by milling.
Iron oxide pigments are used in this finely milled powder form. The disadvantage of this is that the powders tend to form dust, are very liable to clump together in transport and during storage and are difficult to measure out accurately.
It has therefore been proposed in DE-A 3 619 363 also to use iron oxide pigments as pearl granulates in the form of microgranulates in which 90% of the pigment particles measure from 20 to 500 ~m. The microgranulates are prepared LeA 27 208 ~ ~ ~ iJ ,. 2 ~i in spray dryers by atomizing a mixture of pigment and a liguid, preferably water, with the addition of a binder in a spray tower using one-material or multi-material nozzles or atomizer discs.
For iron oxide red and iron oxide brown pigments, this process has the disadvantage that it is necessary to start with the completely prepared pigments.
It is an object of the present invention to prepare iron oxide red and brown pigments by a simpler method with fewer process steps.
This problem was solved by subjecting aqueous iron oxide yellow and/or iron oxide black suspensions to spray granulating drying and treating the resulting microgranulates, which had diameters of 20 to 600~um, either immediately or after an interval at temperatures from 200 to 1000C.
The advantage of this process is that it is not necessary to start with the finished iron oxide red or brown pigments for preparing the microgranulates, which would necessitate mashing up the pigments and drying them; instead, preparation of the red or brown pigment by annealing black and/or yellow pigments may now be combined with the preparation of the microgranulates.
The necessary step in the process according to the invention of tempering under oxidizing conditions cause the black or yellow pigment microgranulates to undergo a chemical reaction. It is therefore all the more surprising that the microgranulates are not affected in their me~hanical stability by this conversion process and do not break apart.
The pigment microgranulates obtained by the process according to the invention are stable in handling, do not form dust, do not tend to clump together and are free flowing and LeA 27 208 easily measured out.
The starting materials used for the process according to the invention are advantageously filter cakes obtained from the preparation of iron oxide yellow and iron oxide black S pigments by the precipitation or nitrobenzene reduction process, optionally with the addition of water. The tempering step is carried out in an oxidizing atmosphere, in particular when iron oxide black is used as starting material.
Treatment temperatures of from 200C to 600C are sufficient for the preparation of iron oxide brown micro-granulates but temperatures from 700C to 900C should be maintained for iron oxide red pigments.
~Jhen granulating drying and tempering are carried out simultaneously, the annealing apparatus used are preferably hot gas spray reactors, e.g. reaction cyclones.
The separation of the step of granulating drying from that of annealing, is however, also a subject of the present invention. Whereas the first step of spray granulating drying may suitably be carried out in spray towers with slowly rotating discs or with pressure nozzles,also in combination with fluidized beds or in fluidized bed dryers alone, the second step of the process is preferably carried out in directly heated or indirectly heated rotary tubular furnaces. Tempering may also be carried out by fla~h calcination in a high temperature chamber.
The microgranulates obtained by the annealing process may quite well be ground up into pigment powders without any disadvantage. No separate installations are therefore required for the preparation of microgranulates and the preparation of powders. On the contrary, it has been found, in particular for the preparation of red pigments, LeA 27 208 that the annealing of microgranulates results in pigments with better colour shades.
I~iquidizers or binders both of an organic and of an inorganic nature may be added to the starting suspensions of the yellow or black pigments. Whereas organic additives such as carboxymethyl cellulose, molasses or polyacrylates may be deleteriously affected in their action by the subsequent tempering step, inorganic binders such as water glass, silica sol or aluminates for the most part retain their effect.
The present invention also relates to the iron oxide red and iron oxide ~rown pigment microgranulates obtainable by the process according to the invention. The granulates obtained preferably have an agglomerate size of from 20 to 600/um, more preferably from 100 to 3001um, depending on the conditions of atomization and the solids concentration of the suspension used. If the suspensions are introduced into a spray fluidized bed apparatus, the size of the agglomerates may be from 200 to sono ~um.
The invention further relates to the use of the iron oxide red and brown pigment microgranulates according to the invention for colouring building materials, lacquers, plastics and paper.
The process according to the invention is illustrated with the aid of the following Examples but should not be regarded as being limited to the Examples.
In the Examples given, determination of the outflow time from a 4 mm DIN cup (DIM 53 211 of April 1974) was applied analogously to the microgranulates to be tested~
_5_ LeA 27 208 2 ~
ExamPle 1 1-0% by weight of polystable AMV solution (t~ade product of Chemische Fabrik Stockhausen GmbH) corresponding to 0-4%
by weight of ammonium polyacrylate, based on iron oxide black, is added to the iron oxide black sludge obtained as intermediate product of the preparation of the iron oxide red pigment Bayferrox 120 N and the mixture, which has a solids content of 53% by weight, is introduced into a spray dryer. The temperatures of the hot gases are 350C at the entrance to the dryer and 100C at the exit. The suspension is conveyed through a piston membrane pump at an inlet pressure of 9 bar into a liquid pressure nozzle in which atomization takes place. A dry product is obtained in spherical form with diameters of from 100 to 250~um. When annealed in a rotary tubular furnace in an oxidizing atmosphere at 800C, these iron oxide black microgranulates give rise to iron oxide red microgranulates which are stable in handling and have substantially the same spherical form and size as the black granulates from which they are obtained.
They are stable in handling, have no tendency to form dust and have good flow properties, as indicated by their outflow time from a 4 mm DIN cup of 60 seconds. Compared with the product obtained hy annealing pulverulent iron oxide black starting materials, the microgranulates have the advantage, due to the more uniform heat treatment, of giving rise to an iron oxide red with less sintering, which is noticeable by the less pronounced blue tinge in the colour.
Example 2 The procedure is the same as in Example 1 except that the iron oxide black microgranulates are not heated to 800C
but to,450C in a~ oxidizing atmosphere. The iron oxide brown obtained in microgranulate form has good flow proper-ties, with outflow times in the region of 61 seconds, is LeA 27 208 ~2~2~
stable in handling and does not form dust. The granulate diameters are from 100 to 250~um, similar to those of the starting granulate. The colour shade is identical to that of powder which has been annealed under identical conditions.
ExamPle 3 An aqueous suspension of the manufactured iron oxide yellow Bayferrox 920 (trade product of Bayer AG) containing 27% by weight of goethite is atomized from a nozzle into a high temperature reaction cyclone. When the temperature of the reactor is 850C, a fluid iron oxide red microgranulate with attractive colour shade is obtained after flash calcination in an oxidizing atmosphere. The microgranulates, which are stable in handling, have a diameter of from 20 to 100 /um.
Example 4 The iron oxide black suspension from Example 1 is introduced into the high temperature reaction cyclone instead of the aqueous iron oxide yellow suspension. The procedure is otherwise the same as in Example 3. A finely divided, non-dusting microgranulate of iron oxide red having diameters offrom 50 to 150/um is obtained.
LeA 27 208
Iron Oxide Red and Iron Oxide Brown Microgranulates, a Process for their Preparation and their Use This invention relates to microgranulates of iron oxide red or iron oxide brown pigments, to a process for their preparation and to their use.
Iron oxide red pigments consist of finely divided haematite with a corundum struc:ture. Iron oxide brown pigments are generally composed of mixtures of haematite (iron oxide red) with magnetite (iron oxide black) and goethite (iron oxide yellow). They may also consist of a homogeneous product of maghaemite which crystallizes in the spinel lattice. ~oth iron oxide red and iron oxide brown pigments are chemically Fe2O3. Whereas iron oxide red is known as a-Fe2O3, the uniform iron oxide brown may be termed y-Fe203 (Ullmanns Encyklopadie der tech. Chemie, published by Verlag Chemie GmbH, Weinheim 1979, 4th Edition, Volume 18, pages 600 to 604).
Iron oxide red pigments may be prepared by various methods.
One method fre~uently employed consists of annealing iron LeA 27 208 2~v~
oxide black or iron oxide yellow in an oxidizing atmosphere at temperatures in the region of 800C. Homogeneous iron oxide brown is obtained by the same method ~ut at lower temperatures of about 200 to 600C, the exact shade obtained varying according to the temperature employed.
Iron oxide yellow pigments are normally obtained by the precipitation process in which iron (II) salts are reacted with alkalis under oxidizing conditions, in most cases by gassing with air, and selectively at an acid or a strongly alkaline pH to be converted into goethite (a-FeOOH). In another process, iron(II) salt solutions which have previously been oxidized by air are hydrolysed in the presence of metallic iron (Penniman process).
Iron oxide black pigments consisting of Fe3O4 may also be obtained by precipitation from iron(II) salt solutions with introduction of air, the process being carried out close to the neutral point. The black pigment may also be prepared by the reduction of aromatic nitro compounds to the corresponding amines with metallic iron.
In the processes mentioned above, the pigments are obtained as intermediate products in the form of aqueous suspensions which are filtered and washed. The final step of the process to the finished pigment is carried out by drying the filter cake obtained, followed by milling.
Iron oxide pigments are used in this finely milled powder form. The disadvantage of this is that the powders tend to form dust, are very liable to clump together in transport and during storage and are difficult to measure out accurately.
It has therefore been proposed in DE-A 3 619 363 also to use iron oxide pigments as pearl granulates in the form of microgranulates in which 90% of the pigment particles measure from 20 to 500 ~m. The microgranulates are prepared LeA 27 208 ~ ~ ~ iJ ,. 2 ~i in spray dryers by atomizing a mixture of pigment and a liguid, preferably water, with the addition of a binder in a spray tower using one-material or multi-material nozzles or atomizer discs.
For iron oxide red and iron oxide brown pigments, this process has the disadvantage that it is necessary to start with the completely prepared pigments.
It is an object of the present invention to prepare iron oxide red and brown pigments by a simpler method with fewer process steps.
This problem was solved by subjecting aqueous iron oxide yellow and/or iron oxide black suspensions to spray granulating drying and treating the resulting microgranulates, which had diameters of 20 to 600~um, either immediately or after an interval at temperatures from 200 to 1000C.
The advantage of this process is that it is not necessary to start with the finished iron oxide red or brown pigments for preparing the microgranulates, which would necessitate mashing up the pigments and drying them; instead, preparation of the red or brown pigment by annealing black and/or yellow pigments may now be combined with the preparation of the microgranulates.
The necessary step in the process according to the invention of tempering under oxidizing conditions cause the black or yellow pigment microgranulates to undergo a chemical reaction. It is therefore all the more surprising that the microgranulates are not affected in their me~hanical stability by this conversion process and do not break apart.
The pigment microgranulates obtained by the process according to the invention are stable in handling, do not form dust, do not tend to clump together and are free flowing and LeA 27 208 easily measured out.
The starting materials used for the process according to the invention are advantageously filter cakes obtained from the preparation of iron oxide yellow and iron oxide black S pigments by the precipitation or nitrobenzene reduction process, optionally with the addition of water. The tempering step is carried out in an oxidizing atmosphere, in particular when iron oxide black is used as starting material.
Treatment temperatures of from 200C to 600C are sufficient for the preparation of iron oxide brown micro-granulates but temperatures from 700C to 900C should be maintained for iron oxide red pigments.
~Jhen granulating drying and tempering are carried out simultaneously, the annealing apparatus used are preferably hot gas spray reactors, e.g. reaction cyclones.
The separation of the step of granulating drying from that of annealing, is however, also a subject of the present invention. Whereas the first step of spray granulating drying may suitably be carried out in spray towers with slowly rotating discs or with pressure nozzles,also in combination with fluidized beds or in fluidized bed dryers alone, the second step of the process is preferably carried out in directly heated or indirectly heated rotary tubular furnaces. Tempering may also be carried out by fla~h calcination in a high temperature chamber.
The microgranulates obtained by the annealing process may quite well be ground up into pigment powders without any disadvantage. No separate installations are therefore required for the preparation of microgranulates and the preparation of powders. On the contrary, it has been found, in particular for the preparation of red pigments, LeA 27 208 that the annealing of microgranulates results in pigments with better colour shades.
I~iquidizers or binders both of an organic and of an inorganic nature may be added to the starting suspensions of the yellow or black pigments. Whereas organic additives such as carboxymethyl cellulose, molasses or polyacrylates may be deleteriously affected in their action by the subsequent tempering step, inorganic binders such as water glass, silica sol or aluminates for the most part retain their effect.
The present invention also relates to the iron oxide red and iron oxide ~rown pigment microgranulates obtainable by the process according to the invention. The granulates obtained preferably have an agglomerate size of from 20 to 600/um, more preferably from 100 to 3001um, depending on the conditions of atomization and the solids concentration of the suspension used. If the suspensions are introduced into a spray fluidized bed apparatus, the size of the agglomerates may be from 200 to sono ~um.
The invention further relates to the use of the iron oxide red and brown pigment microgranulates according to the invention for colouring building materials, lacquers, plastics and paper.
The process according to the invention is illustrated with the aid of the following Examples but should not be regarded as being limited to the Examples.
In the Examples given, determination of the outflow time from a 4 mm DIN cup (DIM 53 211 of April 1974) was applied analogously to the microgranulates to be tested~
_5_ LeA 27 208 2 ~
ExamPle 1 1-0% by weight of polystable AMV solution (t~ade product of Chemische Fabrik Stockhausen GmbH) corresponding to 0-4%
by weight of ammonium polyacrylate, based on iron oxide black, is added to the iron oxide black sludge obtained as intermediate product of the preparation of the iron oxide red pigment Bayferrox 120 N and the mixture, which has a solids content of 53% by weight, is introduced into a spray dryer. The temperatures of the hot gases are 350C at the entrance to the dryer and 100C at the exit. The suspension is conveyed through a piston membrane pump at an inlet pressure of 9 bar into a liquid pressure nozzle in which atomization takes place. A dry product is obtained in spherical form with diameters of from 100 to 250~um. When annealed in a rotary tubular furnace in an oxidizing atmosphere at 800C, these iron oxide black microgranulates give rise to iron oxide red microgranulates which are stable in handling and have substantially the same spherical form and size as the black granulates from which they are obtained.
They are stable in handling, have no tendency to form dust and have good flow properties, as indicated by their outflow time from a 4 mm DIN cup of 60 seconds. Compared with the product obtained hy annealing pulverulent iron oxide black starting materials, the microgranulates have the advantage, due to the more uniform heat treatment, of giving rise to an iron oxide red with less sintering, which is noticeable by the less pronounced blue tinge in the colour.
Example 2 The procedure is the same as in Example 1 except that the iron oxide black microgranulates are not heated to 800C
but to,450C in a~ oxidizing atmosphere. The iron oxide brown obtained in microgranulate form has good flow proper-ties, with outflow times in the region of 61 seconds, is LeA 27 208 ~2~2~
stable in handling and does not form dust. The granulate diameters are from 100 to 250~um, similar to those of the starting granulate. The colour shade is identical to that of powder which has been annealed under identical conditions.
ExamPle 3 An aqueous suspension of the manufactured iron oxide yellow Bayferrox 920 (trade product of Bayer AG) containing 27% by weight of goethite is atomized from a nozzle into a high temperature reaction cyclone. When the temperature of the reactor is 850C, a fluid iron oxide red microgranulate with attractive colour shade is obtained after flash calcination in an oxidizing atmosphere. The microgranulates, which are stable in handling, have a diameter of from 20 to 100 /um.
Example 4 The iron oxide black suspension from Example 1 is introduced into the high temperature reaction cyclone instead of the aqueous iron oxide yellow suspension. The procedure is otherwise the same as in Example 3. A finely divided, non-dusting microgranulate of iron oxide red having diameters offrom 50 to 150/um is obtained.
LeA 27 208
Claims (15)
1. A process for the preparation of iron oxide red or iron oxide brown pigment microgranulates, characterised in that aqueous suspensions comprising iron oxide yellow or iron oxide black are subjected to spray granulating drying and the microgranu-lates thus obtained, which have diameters of from 20 to 600µm, are tempered by heating at temperatures of from 200°C to 1000°C.
2. A process according to Claim 1, characterised in that the aqueous suspension is formed from filter cakes obtained by the production of iron oxide yellow or iron oxide black from a precipitation or a nitrobenzene reduction process.
3. A process according to Claim 1 characterised in that the tempering step is carried out in an oxidizing atmosphere.
4. A process according to Claim 1 characterised in that iron oxide brown pigment microgranulates are obtained and tempered by heating at temperature from 200°C to 600°C
5. A process according to Claim 1 characterised in that iron oxide red pigment microgranulates are obtained and tempered by heating at temperatures from 700°C to 900°C.
6. A process according to Claim 1 characterised in that inorganic or organic binders are added to the aqueous suspension.
7. A process according to claim 1 wherein the tempering step is performed immediately after the drying step.
8. A process according to Claim 1 characterised in that formation of the granulate and tempering are carried out in one process step.
Le A 27 208 - 8 -
Le A 27 208 - 8 -
9. A process according to Claim 1 characterised in that formation of the granulate and tempering are carried out in a hot gas spray reactor.
10. A process according to Claim 1 characterised in that formation of the granulate and tempering are carried out in two separate process steps.
11. A process according to Claim 10 characterised in that formation of the granulate is carried out in an atomization dryer and tempering is carried out in a rotary tubular furnace or a high temperature chamber.
12. Iron oxide red pigment microgranulates produced by the process of Claim 1.
13. Iron oxide brown pigment microgranulates produced by the process of Claim 1.
14. Building materials, lacquers, plastics and paper containing the microgranulates produced by the process of Claim 1.
15. Pigment powders produced by the grinding of the microgranulates produced by the process of Claim 1.
Le A 27 208 - 9 -
Le A 27 208 - 9 -
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3932166.5 | 1989-09-27 | ||
| DE3932166A DE3932166A1 (en) | 1989-09-27 | 1989-09-27 | IRON OXIDE RED AND IRON OXIDE BROWN MICROGRANULATES, METHOD FOR THE PRODUCTION AND USE THEREOF |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2026120A1 true CA2026120A1 (en) | 1991-03-28 |
Family
ID=6390259
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002026120A Abandoned CA2026120A1 (en) | 1989-09-27 | 1990-09-25 | Iron oxide red and iron oxide brown microgranulates, a process for their preparation and their use |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0419964B1 (en) |
| JP (1) | JPH03126625A (en) |
| AU (1) | AU632853B2 (en) |
| CA (1) | CA2026120A1 (en) |
| DE (2) | DE3932166A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7186395B2 (en) | 2001-04-10 | 2007-03-06 | Basf Aktiengesellschaft | Iron oxides with a higher degree of refining |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2079014T3 (en) * | 1990-10-24 | 1996-01-01 | Bayer Ag | PROCEDURE FOR DYING CONSTRUCTION MATERIALS. |
| AT398967B (en) * | 1992-03-10 | 1995-02-27 | Veitsch Radex Ag | METHOD FOR PRODUCING A FINE-PART OXIDE POWDER |
| US5837051A (en) * | 1994-12-27 | 1998-11-17 | Bayer Ag | Process for the thermal treatment of iron oxides in a circulating fluidized bed |
| DE19649756B4 (en) * | 1996-04-18 | 2005-05-25 | Bayer Chemicals Ag | Process for the preparation of briquetting and pressed granules from carbon black pigments and their use |
| DE102004024013A1 (en) * | 2004-05-14 | 2005-12-01 | Bayer Chemicals Ag | Color pure, readily dispersible iron oxide red pigments with high grinding stability |
| JP6388104B2 (en) * | 2013-11-01 | 2018-09-12 | 戸田工業株式会社 | Iron oxide particle powder, paint and resin composition using the iron oxide particle powder |
| RU2649430C2 (en) * | 2013-11-08 | 2018-04-03 | Лэнксесс Спешалти Кемикалс Ко., Лтд. | Production of red iron oxide pigment |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB799202A (en) * | 1955-06-23 | 1958-08-06 | John Mcnicholl | Improvements in or relating to the preparation of iron derivatives |
| US3004504A (en) * | 1958-07-03 | 1961-10-17 | Abbenante Anthony | Machine for turning and spreading over-lock stitched garments |
| DE1293366B (en) * | 1960-07-26 | 1969-04-24 | Farbenfabriken Bayer Ag Werk U | Process for the production of iron oxide brown pigments |
| US3406228A (en) * | 1964-06-17 | 1968-10-15 | Cabot Corp | Method of producing extremely finely-divided oxides |
| US3533820A (en) * | 1965-04-13 | 1970-10-13 | Southwest Enterprises Inc | Production of iron oxide pigments |
| NL7906213A (en) * | 1978-10-04 | 1980-04-09 | Thann & Mulhouse | RED IRON OXYDE PIGMENT AND METHOD FOR PREPARING IRON OXIDE OF PIGMENT QUALITY FROM WASTE IRON (II) SULFATE. |
| US4436681A (en) * | 1982-05-17 | 1984-03-13 | Barczak Virgil J | Process for producing iron oxide weighting material from iron chloride solutions |
| DE3619363A1 (en) * | 1986-06-09 | 1987-12-10 | Brockhues Chem Werke Ag | METHOD FOR COLORING CONCRETE |
| DE3716300A1 (en) * | 1987-05-15 | 1988-11-24 | Bayer Ag | NEW COLOR-PURE IRON OXIDE PIGMENTS, METHOD FOR THEIR PRODUCTION AND THEIR USE |
| DE3910779A1 (en) * | 1989-04-04 | 1990-10-11 | Bayer Ag | IRON-OXIDE-BLACK PIGMENT GRANULES, METHOD FOR THE PRODUCTION AND USE THEREOF |
| DE3930098A1 (en) * | 1989-09-09 | 1991-03-14 | Basf Lacke & Farben | METHOD FOR PRODUCING INORGANIC OXIDIC PIGMENTS OR OXIDIC CERAMIC COLOR BODIES |
-
1989
- 1989-09-27 DE DE3932166A patent/DE3932166A1/en not_active Withdrawn
-
1990
- 1990-09-14 EP EP90117703A patent/EP0419964B1/en not_active Expired - Lifetime
- 1990-09-14 DE DE90117703T patent/DE59004210D1/en not_active Expired - Lifetime
- 1990-09-25 CA CA002026120A patent/CA2026120A1/en not_active Abandoned
- 1990-09-25 AU AU63151/90A patent/AU632853B2/en not_active Ceased
- 1990-09-26 JP JP2256807A patent/JPH03126625A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7186395B2 (en) | 2001-04-10 | 2007-03-06 | Basf Aktiengesellschaft | Iron oxides with a higher degree of refining |
Also Published As
| Publication number | Publication date |
|---|---|
| AU6315190A (en) | 1991-04-11 |
| JPH03126625A (en) | 1991-05-29 |
| AU632853B2 (en) | 1993-01-14 |
| DE3932166A1 (en) | 1991-04-04 |
| DE59004210D1 (en) | 1994-02-24 |
| EP0419964B1 (en) | 1994-01-12 |
| EP0419964A3 (en) | 1991-12-18 |
| EP0419964A2 (en) | 1991-04-03 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Discontinued |