GB2271768A - A process for the production of pure-colored iron oxide direct red pigments - Google Patents
A process for the production of pure-colored iron oxide direct red pigments Download PDFInfo
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- GB2271768A GB2271768A GB9321766A GB9321766A GB2271768A GB 2271768 A GB2271768 A GB 2271768A GB 9321766 A GB9321766 A GB 9321766A GB 9321766 A GB9321766 A GB 9321766A GB 2271768 A GB2271768 A GB 2271768A
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- iron
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- seed suspension
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- 238000000034 method Methods 0.000 title claims abstract description 37
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 title claims abstract description 29
- 239000001054 red pigment Substances 0.000 title claims abstract description 21
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 12
- 239000000725 suspension Substances 0.000 claims abstract description 71
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 46
- 239000000243 solution Substances 0.000 claims abstract description 25
- 229910052742 iron Inorganic materials 0.000 claims abstract description 23
- 239000012266 salt solution Substances 0.000 claims abstract description 14
- 239000003513 alkali Substances 0.000 claims abstract description 13
- 239000007789 gas Substances 0.000 claims abstract description 13
- 230000003647 oxidation Effects 0.000 claims abstract description 13
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 13
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 12
- 239000001301 oxygen Substances 0.000 claims abstract description 12
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims abstract description 11
- 238000001556 precipitation Methods 0.000 claims abstract description 9
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical class [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000002245 particle Substances 0.000 claims abstract description 4
- 239000000049 pigment Substances 0.000 claims description 20
- 150000002505 iron Chemical class 0.000 claims description 13
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 5
- 230000015572 biosynthetic process Effects 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 4
- 229910000015 iron(II) carbonate Inorganic materials 0.000 claims description 3
- 230000001590 oxidative effect Effects 0.000 claims description 3
- 239000004277 Ferrous carbonate Substances 0.000 claims description 2
- RAQDACVRFCEPDA-UHFFFAOYSA-L ferrous carbonate Chemical compound [Fe+2].[O-]C([O-])=O RAQDACVRFCEPDA-UHFFFAOYSA-L 0.000 claims description 2
- 235000019268 ferrous carbonate Nutrition 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 claims 1
- 239000000126 substance Substances 0.000 claims 1
- 238000003786 synthesis reaction Methods 0.000 claims 1
- 235000013980 iron oxide Nutrition 0.000 description 13
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- 239000004922 lacquer Substances 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 6
- 239000004566 building material Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- 238000001354 calcination Methods 0.000 description 3
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 3
- 229910021506 iron(II) hydroxide 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
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 3
- 239000004408 titanium dioxide Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000000635 electron micrograph Methods 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- WTFXARWRTYJXII-UHFFFAOYSA-N iron(2+);iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[Fe+2].[Fe+3].[Fe+3] WTFXARWRTYJXII-UHFFFAOYSA-N 0.000 description 2
- 230000005070 ripening Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 1
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical class [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 229920000180 alkyd Polymers 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 239000001058 brown pigment Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000001034 iron oxide pigment Substances 0.000 description 1
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 description 1
- 229910000462 iron(III) oxide hydroxide Inorganic materials 0.000 description 1
- 229910021519 iron(III) oxide-hydroxide Inorganic materials 0.000 description 1
- 235000021388 linseed oil Nutrition 0.000 description 1
- 239000000944 linseed oil Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000001052 yellow pigment Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- 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
- 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
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
-
- 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
- C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
-
- 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
- C01P2006/12—Surface area
-
- 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
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
-
- 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
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
- C01P2006/62—L* (lightness axis)
-
- 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
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
- C01P2006/63—Optical properties, e.g. expressed in CIELAB-values a* (red-green axis)
-
- 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
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
- C01P2006/64—Optical properties, e.g. expressed in CIELAB-values b* (yellow-blue axis)
-
- 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
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
- C01P2006/65—Chroma (C*)
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Nanotechnology (AREA)
- Materials Engineering (AREA)
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Inorganic Chemistry (AREA)
- Composite Materials (AREA)
- Compounds Of Iron (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
- Paints Or Removers (AREA)
Abstract
A process for the production of pure-colored iron oxide direct red pigments by precipitation of iron(II) salts with an alkali solution and oxidation with oxygen-containing gases to form a seed suspension, addition of iron(II) salt solution and metallic iron or iron(II) salt solution and alkali solution to the seed suspension and oxidation with oxygen-containing gases until the required color tone is obtained wherein the seed suspension is a black magnetite suspension having a specific sunface of >60m<2>g and an average particle size of <0.05 mu m. <IMAGE>
Description
2271768 A PROCESS FOR THE PRODUCTION OF PURE-COLORED IRON OXIDE DIRECT RED
PIGMENTS AND THEIR USE is This invention relates to a process for the production of pure-colored iron oxide direct red pigments by precipitation of iron(H) salts with an alkali solution and oxidation with oxygen-containing gases to form a seed suspension, addition of iron(H) salt solution and metallic iron or iron(H) salt solution and alkali solution to the seed suspension thus obtained and oxidation with oxygen-containing gases until the required color tone is obtained and to their use.
There are four known processes for the production of red iron oxide pigments (T.C. Patton, Pigment Handbook, Vol. 1, New York 1988, page 288). One of these methods is the direct precipitation of red iron oxides which is described in US-A 2,716,595. In this method, an iron(11) salt solution and an alkali solution are mixed in substantially equivalent quantities and air is passed through the iron(II) hydroxide or carbonate suspension obtained. The iron(III) oxide hydroxide seed suspension thus formed is made up into the red pigment in the presence of iron(H) salt by addition of metallic iron, heating and oxidation with oxygen-containing gases.
It is known from DE-B 1 084 405 that red pigments can only be produced from red seed suspensions. According to US-A-3,946,1033, pure red iron oxide seed suspensions are prepared by using seed modifiers.
By virtue of their softness, the pigments produced by this method show improved properties in regard to dispersibility, gloss and flocculation behavior, particularly when used in lacquer systems, by comparison with the pigments produced by calcination of yellow and black iron oxides. In lacquer applications, however, the color purity of the iron oxide red pigments produced by direct precipitation in accordance with US-A-3,946, 103 does not approach that of the red pigments produced by calcination of black and yellow iron oxides.
Accordingly, the problem addressed by the present invention was to provide a process for the production of iron oxide red pigments which would not have any of the disadvantages described above.
A corresponding process has now surprisingly been found, in which a r, 3 black magnetite seed suspension (Fe-,O) is initially prepared and. after a ripening step and after addition of iron(II) salt solution and metallic iron or after addition of iron(H) salt solution and alkali solution- is converted by heating and oxidation with oxvaen-containing gases into a red pigment characterized by highpunty of color.
The seed suspension consists of fine-particle magnetite. It has a specific surface of careater than 60 m2/g (BET nitrogen adsorption, one-point method, DIN 66131) and an average particle size of less than 0.05 Lrn (electron micrograph).
Accordingly, the present invention relates to a process for the production of pure-colored iron oxide direct red pigments by precipitation of iron(H) salts with an alkali solution and oxidation with oxygen-containing gases to form a seed suspension, addition of iron(H) salt solution and metallic iron or iron(H) salt solution and an alkali solution to the seed suspension thus obtained and oxidation with oxygen-containing gases to until the required color tone is obtained, wherein the seed suspension is a black magnetite seed suspension having a specific surface of greater than 60 m.2/g and an average particle size of less than 0.05 Rm.
The fact that pure-colored iron oxide red pigments are obtained by this process is particularly surprising because it is known from US-A-5,076, 848 that the presence of magnetite during the production of iron oxide yellow and red pigments results in distinct losses of color purity.
It is possible in the process according to the invention either to prepare the seed suspension in the suspension itself by establishing suitable conditions or to use separately prepared seeds.
The seed suspension is prepared by precipitation of iron(H) salts with an alkali solution followed by oxidation with oxygen-containing gases.
In one preferred embodiment of the process according to the invention, the seed suspension is prepared by a) b) forming an aqueous iron(II) sulfate solution having a concentration of from about 10 to 80 -A and preferably 20 to 40 g/l, adding about 0.8 to 1.5 and preferably 0.9 to 1.1 equivalents of an alkaline precipitant to said aqueous iron (H) sulfate solution to precipitate a suspension of iron (II) hydroxide or iron(II) carbonate, and C) oxidizing the iron(II) hydroxide or iron(I1) carbonate by intensively aerating said suspension with an oxygen-containing a, 1 = = =S.
Iron(H) salts from steel pickling plants and/or from the production of titanium dioxide may be used with particular advantage for the preparation of the iron(H) sulfate solution.
The temperature prevailing during seed formation is preferably in the range from 30 to 80'C and, more preferably, in the range from 30 to 50"C.
A suspension of iron(][[) hydroxide or carbonate is precipitated by addition of 0.8 to 1.5 equivalents and preferably 0.9 to 1.1 equivalents NaOIL Na,C03, NH3, MgO and/or MgC03 preferably being used.
Precipitation is followed. by Oxidation preferably using air as the oxidizing ag -1 gent. To this end, 20 to '00 liters air per hour and per liter suspension are introduced. A black seed suspension is obtained in which only magnetite (Fe304) can be detected by x-ray phase analysis (Siemens D-500) (ASTM No. 19.
0629). The seed suspension may then be advantageously subjected to ripening for I to 4 hours at 70 to 100'C.
A quantity of seeds of 40 to 30 g/l is preferably used for pigment formation, a quantity of 7 to 20 g/l, calculated as Fe203, being particularly preferred.
Pigment formation may be carried out by two methods. In the first method, metallic iron and iron(III) salt solution are added to the seed suspension which is then heated to 70 to 100'C and preferably to 75 to 90"'C and oxidized by separating the suspension with 0.2 to 50 1 air per hour and per liter suspension until from about the required color tone is obtained. This is the case after seed multiplication by a factor of 2.5 to 10 and preferably 3 to 6.
In the second method, the seed suspension is heated to 70 to 100'C and preferably to 75 to 90'C, iron(II) salt solution and an alkali solution are then added and the suspension is oxidized by aerating the suspension with from about I to 400 1 air per hour and per liter suspension until the required color tone is obtained, the pH value being in the range from 4 to 5.
The salt liquor can be removed by filtration and washing or by sedimentation. The red paste may be processed to slurries or dried and around to form powder-form pigment5.
Soft pure-colored iron oxide red pigments are obtained. a-Fe,O, is detected by x-ray phase analysis (ASTM No. 33.0664).
The color testing of the pigments for lacquer applications was carried out in Alkydal L64 (a product of Bayer AG, an alkyd resin containing 63% linseed oil and 23% phthatic anhydride to which 5% Luvotix HT (a product of Lehmann & Voss) is added to increase viscosity). The pigment volume concentration is 10%.
To test the pigments for applications in the building materials field (DIN 53 237), pressingS were produced from heavy spar. To this end, 0.5 g pigment and 10 g heavy spar were introduced into an approx. 250 ml glass shaking flask. After g addition of 200 steel balls 5 mm in diameter, the contents of the flask were shaken for 3 minutes by means of an automatic table vibrator. The mixture was compressed to form a cylinder.
The CIELAB data (DIN 6174) were determined using a color measuring instrument with an Ulbricht ball (lighting conditions d/8', standard light type C/2'); the surface reflection was included.
Table I shows the colorimetric data of a few pigments produced by the process according to the invention and the corresponding data of a few commercial products.
The color saturation (C) is a measure of the color purity of the piaments.
Both in the lacquer test and in the building materials test, the pigments I produced in accordance with the invention have higher color saturations than the direct red pigments produced by the conventional process according to US- A 3 3,946, 103 (Bayferrox 5 109, a product of Bayer AG) and the red pigments produced by calcination of black pigments obtained, for example, in accordance with DE-A 2 826 941 and DE-A 463 77^1 (Bayferrox 105MO, Bayferrox 1100, products of Bayer 30 AG).
Particularly high red components (a) were obtained in the lacquer test, leading to an aesthetically impressive pure color impression.
-1 In the building, materials test, the aesthetic brick red tones were obtained through the pronounced yellow tinge (b) coupled with the high red component (a)- Pigments produced with seed multiplication by a factor of 1.0 to 1.5 are suitable for use as transparent brown pigments. With a seed multiplication factor of 1.5 to 4, they may be used as transparent or semitransparent red pigments.
The present invention also relates to the use of the iron oxide red pigments produced in accordance -with the invention for rdgnmurg lacquers, plastics, building materials and ceramics both as powder-form piginents and in the form of pastes or slurries.
Figure I is an electron micrograph of a fine-particle magnetite seed produced by the process according to the invention.
The following Examples are intended to illustrate the invention without limiting it in any way.
Example 1
22.3 1 of an iron(11) sulfate solution from the production of titanium dioxide (concentration 25 g/I FeS04) are initially introduced. The temperature is 33'C. 1.35 1 of a 4.75 N NaOH solution are added and the suspension is subsequently oxidized for 25 minutes with 52 1 air per hour and per liter suspension.
A black seed suspension is obtained.
Example 2
22.3 1 of an iron(II) sulfate solution from the production of titanium dioxide (concentration 25 g/I FeS04) are initially introduced. The temperature is 35T. L' 35 1 of a 4.75 N NaOH solution are added and the suspension is subsequently oxidized for 21 minutes with 52 1 air per hour and per liter suspension.
A black seed suspension is obtained. The suspension is heated to 80T and stirred for 2 hours with continuing aeration.
M Example 3
23 ml iron(II) sulfate solution (200 g/l FeS04) 2563 ml water and 450 a metallic iron are added to 4414 ml of the seed suspension produced in accordance ,N,Ith Example 1. After heating to 85'C, the suspension is oxidized with 10 1 air per hour and per liter suspension. After 32 hours, the black seed suspension has been converted into a pure-colored red pigment. The multiplication factor is 33. The 1.
suspension is filtered, washed free from salts, dried at 85'C and the pigment obtained is ground.
Example 4
The procedure is as in Example 33. After 52 hours and seed multiplication by a factor of 4.6, the suspension is filtered, washed free from salts, dried at 85'C and the pigment obtained is ground.
Example 5
3 ml iron(II) sulfate solution (200 -/1 FeS04), 3067 ml water and 450 a metallic iron are added to 3828 ml of the seed suspension prepared in accordance with Example 2. After heating to 85'C, the suspension is oxidized with 7 1 air per hour and per liter suspension. After 19 hours, the black-brown seed suspension has been converted into a pure-colored red pigment. The multiplication factor is 3.5. The suspension is filtered, washed free from salts, dried at 85'C and the pigment obtained is ground.
Table 1 Colorinietric data of iron oxide red pigments Pure tone testing in Alkydalo L 64 (Lacquer applications) Pigment L a b C Remarks Pfizer Croma Red RO 309701) 39.6 28.5 22.2 36.1 Direct red Bayferrox 5 10@2) 40.9 28.5 23.9 37.2 Direct red acc. to US-A-3,46,103 Bayferrox 105M@2) 41.3 29.1 24.4 39 Calcined black iron oxide Example 5 41.4 29.3 25.6 38.9 Testing in heavy spar (building materials applications) Pigment L a b C Remarks Pfizer Croma Red RO 309701) 51 28.8 22.8 36.7 Direct red Bayferrox 5 1 0q)2) 52.9 31.2 32.2 44.8 Direct red acc. to US-A-3,46,103 Bayferrox 11 O(V2) 52.5 30.6 26.9 403 Calcined black iron oxide Example 3 56.9 29.7 38.4 48.5 Example 4 53.5 32.4 34.2 47.1 1) A product of Pfizer 2) A product of Bayer AG
Claims (15)
1. A process for the production of pure-colored iron oxide direct red pigments comprising: Precipitation of iron(H) salts with an alkali solution and oxidation with oxygen-containing gases, adding iron(H) salts solution and nutaMc iron or iron(II) salt solution and an alkali solution to a seed suspension and then oxidation with oxygen-containing gases until the required color tone is obtained, wherein a black magnetite seed suspension having a specific surface of greater than 60 m2/g and an average particle size of less than 0.05 gni is used as the seed suspension for synthesis of the pigment.
2. A process as claimed in claim 1, wherein the seed suspension is prepared by a) b) forming an aqueous iron (H) sulfate solution having a concentration of from about 10 to 80 g/l; by adding about 0.8 to 1.5 and preferably 0.9 to 1.1 equivalents of an alkaline precipitant to said aqueous iron(H) -sulfate solution to precipitate a suspension of iron(H) hydroxide or iron(II) carbonate; and oxidizing the iron(H) hydroxide or iron(H) carbonate by intensively aerating said suspension with an oxygen-containing gas to form said seed suspension.
A process as claimed in claim 2, wherein the precipitation and oxidation steps are carried out at a temperature of from about 30 to 800C.
4. A process as claimed in claim 2, wherein the precipitant comprises at least one substance selected from the group consisting of NaOFL Na2C03, NH3, MgO and MgCO 3
5. A process as claimed in claim 2, wherein the seed suspension is ripened from I to 4 hours at 70 to 100"C.
6. A process as claimed in claim 1, wherein the concentration of seeds in the seed suspension is from about 4 to 30 g/l.
7. A process as claimed in claim 1, wherein metallic iron and iron(II) salt solution are added to the seed suspension, the suspension is then heated to a temperature of from about 70 to 100'C and is then oxidized with 0.2 to 50 1 air z per hour and per liter suspension until the required color is obtained.
8. A process as claimed in claim 1, wherein the seed suspension is heated to a temperature of from about 70 to 100'C and the iron(II) salt solution and alkali solution are added to the seed suspension and the suspensi-on is oxidized with from about I to 400 1 air per hour and per liter suspension until the required color is obtained.
9. A process as claimed in claim 2, wherein the aqueous iron(H) sulfate solution in step a) has a concentration of from about 20 to 40 g/l.
10. A process as claimed in claim 2, wherein the oxygen-contaiMn-,- gas is air.
11. A process as claimed in claim 10, wherein said air is introduced to said suspension of iron(H) hydroxide or iron(]E[) carbonate in a quantity of from about 20 to '300 liters of air per hour and per liter of said suspension.
12. A process as claimed in claim 3, wherein the temperature is from about)0 to 500C.
13.. A process as claimed in claim 6, wherein the concentration of seeds in the seed suspension is from about 7 to 20 g/l.
14. A process as claimed in claim 7, wherein the suspension is heated to a temperature of from about 75 to 900C.
15. A process as claimed in claim 8, wherein the suspension is heated to a temperature of from about 75 to 90"C.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4235946A DE4235946A1 (en) | 1992-10-23 | 1992-10-23 | Process for the production of pure iron oxide direct red pigments and their use |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9321766D0 GB9321766D0 (en) | 1993-12-15 |
| GB2271768A true GB2271768A (en) | 1994-04-27 |
| GB2271768B GB2271768B (en) | 1995-08-16 |
Family
ID=6471261
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9321766A Expired - Fee Related GB2271768B (en) | 1992-10-23 | 1993-10-21 | A process for the production of pure-colored iron oxide direct red pigments and their use |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPH06219750A (en) |
| DE (1) | DE4235946A1 (en) |
| GB (1) | GB2271768B (en) |
| IT (1) | IT1270883B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002026632A1 (en) * | 2000-09-26 | 2002-04-04 | Bayer Aktiengesellschaft | Contact and adsorber granulates |
| WO2015178451A1 (en) * | 2014-05-23 | 2015-11-26 | 戸田工業株式会社 | Method for producing hematite particle powder, paint and resin composition using said hematite particle powder |
-
1992
- 1992-10-23 DE DE4235946A patent/DE4235946A1/en not_active Withdrawn
-
1993
- 1993-10-07 IT ITMI932131A patent/IT1270883B/en active IP Right Grant
- 1993-10-18 JP JP5282123A patent/JPH06219750A/en active Pending
- 1993-10-21 GB GB9321766A patent/GB2271768B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| ITMI932131A0 (en) | 1993-10-07 |
| IT1270883B (en) | 1997-05-13 |
| ITMI932131A1 (en) | 1995-04-07 |
| GB2271768B (en) | 1995-08-16 |
| DE4235946A1 (en) | 1994-04-28 |
| JPH06219750A (en) | 1994-08-09 |
| GB9321766D0 (en) | 1993-12-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20031021 |