MXPA98008602A - Yellow pigments of iron oxide, a metodode production of yellow pigments of oxide dehierro and use of mis - Google Patents

Abstract

The present invention relates to yellow pigments of iron oxide, to a method of producing yellow iron oxide pigments by a method of precipitating iron (II) chloride and an alkaline component, and to the use of the same.

Description

YELLOW PIGMENTS OF IRON OXIDE, A METHOD OF PRODUCTION OF YELLOW YELLOW PIGMENTS OF IRON AND USE OF THEM Field of the Invention The present invention relates to yellow pigments of iron oxide, to a method of producing yellow pigments of iron oxide by a method of precipitation from iron (II) chloride and an alkaline component, and to the use thereof .

Background of the Invention The precipitation methods for the production of yellow pigments of iron oxides have been known for some time. The typical procedure of these processes is described, for example, in Ullmanns Enzykiopádie der technischen Chemie, 5 / a. edition, volume A20, pages 297 et seq. Iron sulphate (II) which is formed during the chemical bath of deoxidizing steel plates or iron (II) sulphate which is formed during the production of titanium dioxide by the sulphate process, are used Ref.028620 usually as the raw material. Large amounts of FeCl2 were formed during the production of synthetic rutile for the production of Ti02. A growing trend towards the use of hydrochloric acid as a deoxidizing chemical bath has been observed for some years, so that large amounts of FeCl2 are also formed here. In addition, what is called the chloride process is increasingly being used throughout the world to produce titanium dioxide. The solutions containing iron (II) chloride are thus increasingly formed by these processes, and should be converted if possible into a valuable material. A common process for using FeCl2 waste solutions is the spray calcination process, in which iron (II) chloride or iron (III) chloride is subjected to oxidative hydrolysis at high temperatures (typically at temperatures higher than 1000 ° C). The final products formed here are iron oxides, typically hematite, and hydrochloric acid, which can also be recycled as a useful substance, for example to the deoxidizing acid bath process. An iron oxide is obtained here, without special purification steps, which as a rule is suitable for the production of hard ferrites. If the soft ferrites are to be produced from the iron oxides obtained in this way, the iron chloride solution which is used has to be subjected in advance to further purification operations, due to which the process reaches be considerably more expensive. Since increasing amounts of iron chloride are being formed, most of which are of inferior quality, and the absorption capacity of the ferrite market is restricted, an alternative is being sought for the production of a valuable substance from the iron chlorides obtained in this way. The discharge of waste directly into the land or the dumping of waste into the sea from these iron chloride solutions is not possible due to environmental reasons.

Detailed description of the invention The object of the present invention was therefore to provide a method which makes it possible for the iron chloride solutions to be converted into valuable substances in an economical manner which is as simple as possible.

It has been proved that it is possible to achieve this object by means of the yellow pigments of iron oxide according to the invention and by the method according to the invention. The present invention therefore provides yellow pigments of iron oxide with a luminosity L * as the complete shading of 62.0 to 64.0 CIELAB units, a value a * of 8.5 to 10.5 CIELAB units and a b * value of 48.5 to 50.5 CIELAB units and with a brightness or illumination L * when they are whitened from 81.6 to 82.5 CIELAB units, a value a * of 3.8 to 4.8 CIELAB units, a b * value of 37.5 to 39.5 CIELAB units, a chromium content of less than 40 mg / kg of iron oxide yellow pigment, a chloride content of between 0.05% to 0.3% by weight, based on the yellow pigment of iron oxide, and a manganese content of 0.007 to 0.055% by weight relative to the yellow pigment of iron oxide. The present invention also relates to a method for the production of yellow pigments of iron oxide by a precipitation method, characterized in that a) an alkaline component is added to a solution of Fe (II) acid chloride with an FeCl2 content of 50 to 450 g / l, stirring intensively and in an amount which is sufficient to adjust the pH of the solution to between 3 and 5, b) a flocculating agent is optionally added additionally to the solution, before or after the addition of the alkaline component or together with the alkaline component, c) the oxidation is optionally carried out after the addition of the alkaline component and the flocculating agent which is optionally added, d) the solid formed after the treatment in a) to c) is separated from the solution, e) the solution formed in d) is added to a suspension of a-FeOOH nuclei prepared by a precipitation method, in an amount corresponding to 4 to 8 times the molar amount of iron in the total suspension of nuclei (especially the iron of the iron oxide-hydroxide and the iron of an iron compound that did not react), f) the suspension obtained in e) is heated to a temperature of 30 to 95 ° C, preferably 30 to 85 ° C, preferably of particular way from 55 to 75 ° C, with good mixing from start to finish of the operation, g) the oxidation is subsequently carried out with an oxidizing agent, wherein the oxidizing agent is added in such a way that 0.5 to 10% mol of iron per hour, preferably 0.5 to 2.0% mol of iron per hour, is oxidized and at the same time the pH is increased, with an alkaline component, at a rate of 0.01 to 0.4 pH units / hour until a final pH of 3.0 to 5.0, h) further oxidation is optionally carried out at a constant pH of between 3.0 and 5.0, i) the oxidation is terminated as soon as the Fe (II) content of the suspension is less than 1 mol%, j) the solid of i) is finally separated, washed, dried and milled.

Sodium hydroxide, sodium carbonate, magnesium carbonate, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide or ammonia are preferably used as the alkaline component. The iron chloride (II) solutions of the acid-deoxidizing bath of the steel, or the iron (II) chloride solutions of the Ti02 production by the chloride process, can be used. The method according to the invention can advantageously be carried out as follows: an amount of the sodium hydroxide solution such that a pH from 3 to 5 is obtained, is added to a solution of iron (II) chloride with an FeCl2 content of between 50 and 450 g / 1, with vigorous stirring. Another alkaline component, such as Ca (OH) 2, Na 2 CO 3 or ammonia, etc., may also be used in place of the sodium hydroxide solution. In addition, the behavior in the sedimentation of the hydroxide or carbonate sludge which is obtained, can be improved by adding a flocculating agent. Known flocculating agents, such as polyacrylates or other substances with similar action, can be used for example. Subsequent oxidation can also be carried out to improve the behavior in the sedimentation. This can also lead to several metal cations being converted into oxides or hydroxides of higher valence, which can be separated more easily. The separation of the hydroxide or carbonate sludge formed can be effected by sedimentation, filtration or separation using a separator. The optimal selection of a suitable apparatus or a suitable method depends on the precise test conditions, the flows of the mass and the raw materials used. The iron (II) chloride solution prepared as above is added, in an amount corresponding to 4 to 8 times the molar amount of the iron of the total nucleating material, to a suspension of the a-feOOH nuclei which is prepared by a method of precipitation and in which the cores have a BET surface area of 65 m2 / g, (especially the iron of the hydroxide-iron oxide and the iron of an iron compound that did not react). The suspension that is obtained is heated, preferably with stirring, to a temperature of between 30 and 95 ° C, preferably between 30 and 85 ° C, still more preferably between 55 and 75 ° C. After this temperature has been reached, the oxidation is carried out using an oxidizing agent and, at the same time, the pH is increased at a rate of 0.01 to 0.4 pH units / hour, until a final pH of 3.0 to 5.0. The oxidation rate, which depends on the rate of addition of the oxidizing agent, the temperature, the mixing in the container and the pH, should preferably be between 0.5 and 10% mol iron per hour, more preferably between 0.5% and 2.0% in mol of iron per hour. If the oxidation rate is considerably below the upper limit, the method becomes uneconomical; if the oxidation rate is significantly above the upper limit, a yellow pigment of iron oxide with an undesirable red melt material is obtained. The suspension of the pigment is worked through the known steps of filtration, drying and grinding. The following are examples of oxidizing agents that can be used: - atmospheric oxygen pure oxygen ozone H202 sodium hypochlorite or bleach liquor or calcium hypochlorite chlorites or chlorates perchlorates nitrates chlorine. The oxidation is preferably terminated as soon as the Fe (II) content of the suspension is less than 1 mol%. Further oxidation can be carried out until the complete reaction is achieved. Apart from the use of iron (II) chloride solutions, both the iron (II) chloride and the iron (II) sulphate solutions can be used, both for the production of the cores and for the production of pigments. The preferred embodiment is the exclusive use of iron (II) chloride solutions. The iron (II) chlorides which are formed during the production of Ti02 by the chloride process can also be used, for example, such as those which have been previously reduced to iron (II) chloride with metallic iron. The yellow pigments of iron oxide which are obtained are particularly suitable for the coloring of plastics and paper and for the production of dye preparations such as latex paints, lacquers and dyes. They can be used for coloring building materials. They are also suitable for the production of coloring agents for the food industry. Unless otherwise specified, the parts and percentages in the following examples are given as parts and percentages by weight. Shading or color tone is determined by the procedure specified later. 1. Preparation in an alkyd resin lacquer to measure total shading Quantities of heavy pigments in: Fe red (hematite) 1.00 g Fe yellow (goethite) 0.80 g Fe black (magnetite) 1.00 g The pigment is prepared with a disc grinding machine (mill) of color, in a test binder vehicle without drying. The test binder vehicle (paste) consists of two components.

Component 1: Component 1 was an alkyd resin binder vehicle based on linseed oil and italic anhydride. It corresponded to the mentioned specifications which are given in the DIN EN ISO 787-24 (October 1995), ISO 787-25: 1993 and DIN 55983 (December 1983) standards as the requirements for a test binder vehicle for coloring pigments. The product used was © SACOLYD L 640 (Krems Chemie), formerly © ALKYDALL L 64 (Bayer AG).

Component 2 Component 2 was a rheological additive which was added to the paste to ensure a thixotropic behavior. The additive employed herein was a modified hydrogenated castor oil, in a powdered form, ®LUVOTHIX HT (Lehmann &Voss &Co.), at a 5.0% concentration. The LUVOTHIX HT was dissolved in the SACOLYD L 640 in the range of 75 to 95 ° C. The compact, cooled mass was once passed through a three-roll mill. With this step, the pasta is complemented.

A disk milling machine (mill) was used, as described in DIN EN ISO 8780-5 (April 1995). An ENGELSMANN JEL 25/53 mill was used which had an effective disk diameter of 24 cm. The rotation speed of the lower disc was approximately 75 min.-1. The force between the discs is adjusted to approximately 0.5 kN by suspending a load weight of 2.5 kg on the loading bracket. The aforementioned amount of the pigment and 5.00 g of the paste were dispersed in three steps of 25 rotations each, by the process described in DIN EN ISO 8780-5 (April 1995) section 8.1. The paste-pigment mixture is then sprayed on a pulp tray, the function of which corresponds to that of the pulp tray in DIN 55983 (December 1983). The scraping blade forming part of the pulp tray was removed or extracted through the recess in the tray which was filled with the pigment-paste mixture in such a way that a smooth surface was produced. In the course of this procedure, the doctor blade was moved in one direction at a speed of approximately 3 to 7 cm / s. The smooth surface was measured in the interval of a few minutes. 2. Bleached (color intensity) The pigment was prepared in a disc grinding machine (mill), in a non-drying test binder vehicle. The test binder vehicle (pulp) consisted of two components.

Component 1: Component 1 was an alkyd resin binder vehicle based on linseed oil and italic anhydride. It corresponded to the specifications which are given in the standards DIN EN ISO 787-24 (October 1995), ISO 787-25: 1993 and DIN 55983 (December 1983) as the requirements for a test binder vehicle for coloring pigments. The product used was SACOLYD L 640.

Component 2: Component 2 is a rheological additive which was added to achieve a thixotropic behavior of the pulp. The additive used here was a hydrogenated castor oil, modified, in pulverized form, LUVOTHIX HT, in a concentration of 5.0%.

The LUVOTHIX HT dissolves in the SACOLYD L 640 in the range of 75 to 95 ° C. The compact, cooled mass is passed once through a three-roll mill. With this step, the pasta is complemented. A disk milling machine (mill) was used, as described in DIN EN ISO 8780-5 (April 1995). An ENGELSMANN JEL 25/53 mill was used, which had an effective disk diameter of 24 cm. The rotation speed of the lower disc was approximately 75 min. "1 The force between the discs was adjusted to approximately 0.5 kN by suspending a load weight of 2.5 kg on the loadboard, a commercially available titanium dioxide pigment. , © BAYERTITAN R-KB-2 (Bayer AG), was used as the bleaching agent.The composition of R-KB-2 corresponds to that of type R 2 in ISO 591-1977.If another R 2 pigment is used instead of R-KB-2, different CIELAB coordinates can be obtained in the measurement of color: 0.400 g of the pigment, 2.000 g of BAYERTITAN R-KB-2 and 3.00 g of the paste are dispersed in five steps of 25 rotations each, by the process described in DIN EN ISO 8780-5 (April 1995) Section 8.1. The pigment-paste mixture was subsequently sprayed into a pulp tray, the function of which corresponds to that of the pulp tray in DIN 55983 (December 1983). The doctor blade that is part of the pasta tray is removed or extracted through the recess in the tray which is filled with the pigment-pigment mixture in such a way that a smooth surface is formed. In the course of this procedure, the doctor blade was moved in one direction at a speed of approximately 3 to 7 cm / s. The smooth surface was measured over the course of a few minutes. 3. Colorimeter A spectrophotometer ("colorimeter") was used which had a measurement geometry of d / 8 without a trap for brightness. This geometry of the measurement is described in ISO 7724 / 2-1984 (E), Item 4.1.1, in DIN 5033, Part 7 (July 1983) Point 3.2.4 and in DIN 53236 (January 1983), Item 7.1. 1. A DATAFLASH 200 measuring instrument provided by Datacolor International was used. The colorimeter was calibrated against a white ceramic working standard, as described in ISO 77242-1984, (E) Point 8.3. The reflection data of the working standard against an ideal matt white body were stored in the measuring instrument, so that after the calibration with the white working standard, all the color measurements were obtained with respect to the white body ideal mate. The black point calibration is carried out with a black hollow body supplied by the colorimeter manufacturer. 4. Measurement of color Any brightness trap present is turned off or disconnected. The temperature of the colorimeter and the test specimen is approximately 25 ° C + 5 ° C. 4. 1 Measurement of the coating of lacquer The coating was placed on the colorimeter so that the opening for the measurement covered a central point on the lacquer coating. The coating must be completely contiguous in its entirety. The opening of the measurement must be completely covered by the coating of the lacquer. Then the measurement is carried out. 4. 2 Measuring the tray for the pasta The color measurement was made immediately after the spraying in the pulp tray was done. The tray for the filled pasta was placed on the colorimeter so that the opening for the measurement was completely filled by the hole in the tray which was coated with the paste. The tray must be completely contiguous in its entirety. Then the measurement is carried out.

. Calculation of the coordinates of CIÉ The coordinates of CIÉ 1976 (L *, a *, b *) (abbreviated as CIELAB) of a reflection spectrum are dependent on the limiting conditions selected for measurement and evaluation. The data given for the wavelength range from 400 nm to 700 nm and the 20 nm range are applicable to the Dataflash 2000 colorimeters commonly in use (situation as of 7/97). Only the coordinates L *, a * and b * are given. All other amounts are redundant. The coordinates of CIÉ L *, a * and b * of 1976 are calculated from the reflection spectrum measured according to the calculation instructions in ASTM E 308-1985, Point 7. The weighting functions of the standard C illuminant and the observer colorimetric standard at 2 °, 1931 ASTM E 308-1985, Table 5.6 were used. The wavelength range is between 400 nm and 700 nm. The wavelength range was 20 nm. No brightness is deducted in the calculation. The results of L *, a * and b * were rounded to whole numbers. The coordinates of CIÉ are cited in DIN 5033 Part 3 (July 1992) as the coordinates of the solid of color L * a * b *. In ISO 7724 / 3-1984 the abbreviation of CIELAB solid color is introduced. The coordinates are dimensional.

Determination of chromium and manganese content The chromium and manganese content is determined by ICP-MS. The limit of detection of this method of determination is 10 μg / kg. 7. Determination of chloride content The chloride content is determined by ion chromatography.

The invention is explained in more detail with reference to the following example which does not limit the scope of the invention.

Example 108. 6 1 of a yellow nucleating composition (BET specific surface of 61 m2 / g, 72.7 g / 1 of FeS04, 36.0 g / 1 of a-FeOOH) are introduced into a stirred vessel equipped with a pH controller and an apparatus for the sprayed with air. 169 1 of a pretreated iron (II) chloride solution containing 228.6 g / 1 of FeCl 2 was pumped into this nucleating suspension. The sodium hydroxide solution [300 g / 1] was then added at a rate such that the pH of the suspension rose to 0.2 units per hour. The batch was oxidized simultaneously with 80 1 of air per hour. The increase in pH was terminated when a pH of 3.85 was reached. This pH was kept constant with the sodium hydroxide solution. The spray system remained in action. The reaction was terminated as soon as the Fe (II) content was less than 1 mol%. The yellow iron oxide pigment obtained was filtered, washed with water, spray dried and milled in a steam jet mill. The product exhibited the following absolute color properties and color properties compared to Bayferrox 3905 (a product of Bayer AG), respectively.

Measurement of color intensity (when blanked with Bayertitan R-KB2): Color intensity: 100% (reference: Bayferrox® 3905 Standard 87) Delta a *: 0.1 units CIELAB Delta b *: -0.6 CIELAB units Absolute values: L *: 82.1 CIELAB units a *: 4.2 CIELAB units b *: 38.0 CIELAB units Measurement of color intensity (such as total shading, reference: Bayferrox® 3905 Standard 87) Delta L *. -0.1 units CIELAB Delta a *: -0.1 units CIELAB Delta b *: -0.7 units CIELAB Absolute values: L *: 63.4 units CIELAB a *: 9.0 units CIELAB b *: 48.9 units CIELAB Cr content: 10 mg / kg pigment Mn content: 0.013% with respect to pigment Cl content: 0.12% with respect to the pigment.

Comparative example 108. 6 1 of a yellow nucleating composition (BET specific surface of 61 m2 / g, 72.7 g / 1 of FeS04, 36.0 g / 1 of a-FeOOH) are introduced into a stirred vessel equipped with a pH controller and an apparatus for the sprayed with air. 169 1 of a solution of iron (II) chloride, which has not been pretreated and which contained 228.6 g / 1 of FeCl2, was pumped into this nucleating suspension. The sodium hydroxide solution [300 g / 1] was then added at a rate such that the pH of the suspension rose to 0.2 units per hour. The batch was oxidized simultaneously with 80 1 of air per hour. The increase in pH was terminated when a pH of 3.85 was reached. This pH was kept constant with the sodium hydroxide solution. The spray system remained in action. The reaction was terminated as soon as the Fe (II) content was less than 1 mol%.

The yellow iron oxide pigment obtained was filtered, washed with water, spray dried and milled in a steam jet mill. The product exhibited the following absolute color properties and color properties compared to Bayferrox 3905 (a product of Bayer AG), respectively. Measurement of color intensity (when blanked with Bayertitan R-KB2): Color intensity: 100% (reference: Bayferrox® 3905 Standard 87) Delta a *: 0.1 units CIELAB Delta b *: -0.4 CIELAB units Absolute values: L *: 82.1 CIELAB a * units: 4.3 CIELAB units b *: 38.2 CIELAB units Measurement of color intensity (such as total shading, reference: Bayferrox® 3905 Standard 87) Delta L *. -0.7 CIELAB Delta a * units: -0.1 units CIELAB Delta b * -1.9 CIELAB units Absolute values: L *: 62.7 units CIELAB a *: 9.1 units CIELAB b *: 47.7 units CIELAB Cr content: 180 mg / kg pigment Mn content: 0.017% with respect to the pigment Cl content: 0.12% with respect to the pigment.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following

Claims (15)

1. A yellow iron oxide pigment, characterized in that it has: a) for total shading, one illumination, L *, from 62.0 to 64.0 CIELAB units, a value a * of 8.5 to 10.5 CIELAB units, and a b * value of 48.5 to 50.5 CIELAB units; b) when bleached, one illumination, L *, from 81.6 to 82.5 CIELAB units, a value a * from 3.8 to 4.8 CIELAB units, and a b * value from 37.5 to 39.5 CIELAB units; Y c) based on the pigment, 0.007 to 0.55% by weight of Mn, 0.05 to 0.3% by weight of Cl and less than 40 mg / kg of Cr.

2. A process for producing a yellow pigment of iron oxide, by precipitation, characterized in that it comprises: a) intensely mixing sufficient quantities of an alkaline component with an acid solution of 50-450 g / 1 of FeCl 2, to adjust the pH of the solution to between 3 and 5, b) optionally adding a flocculation adjuvant to the FeCl 2 solution in step a) before, after or together with the addition of the alkaline component; c) optionally exposing the solution of steps a) or b) to an oxidation; d) separating the solid resulting from steps a), b) or c) of the solution; e) add the solution from step d) to a suspension of a-FeOOH cores produced by the precipitation process, in an amount corresponding to 4 to 8 times the molar amount of the total iron based on the iron oxide-hydroxide and the iron compound that did not react, in the suspension of the nuclei; f) heating the suspension formed in e) from 30 to 95 o C by mixing from start to finish; g) oxidize the material resulting from step f) by adding enough oxidizing agent to oxidize 0.5 to 10% in mol of iron per hour while increasing the pH to a final pH of 3.0 to 5.0 by adding enough alkaline component, to raise the pH to a speed of 0.01 to 0.4 pH units / hour; h) after step g), the oxidation is optionally continued while keeping the pH constant at a value between 3.0 and 5.0; i) stopping the oxidation when the Fe (II) content of the suspension of step g) or h) is less than 1 mol%; j) separating, washing, drying and grinding the iron oxide yellow pigment from step i).

3. The process according to claim 2, characterized in that the temperature in step f) is from 30 to 85 ° C.

4. The process according to claim 2, characterized in that the temperature in step f) is from 55 to 75 ° C.

5. The process according to claim 2, characterized in that the oxidation rate in step g) is from 0.5 to 2.0% mol per hour.

6. The process according to claim 2, characterized in that the alkaline component is selected from the group consisting of sodium hydroxide, sodium carbonate, magnesium carbonate, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide and ammonia. .

7. A yellow iron oxide pigment produced by the precipitation process, characterized in that it comprises: a) thoroughly mixing sufficient quantities of an alkaline component with an acid solution of 50-450 g / 1 of FeCl2, to adjust the pH of the solution to between 3 and 5, b) optionally adding a flocculation adjuvant to the FeCl 2 solution in step a) before, after or together with the addition of the alkaline component; c) optionally exposing the solution of steps a) to b) to an oxidation; d) separating the solid resulting from steps a), b) or c) of the solution; e) add the solution from step d) to a suspension of a-FeOOH cores produced by the precipitation process, in an amount corresponding to 4 to 8 times the molar amount of the total iron based on the iron oxide-hydroxide and the iron compound that did not react in the suspension of the nuclei; f) heating the suspension formed in e) in the range of 30 to 95 ° C with mixing from start to finish; g) oxidize the material resulting from step f) by adding enough oxidizing agent to oxidize 0.5 to 10% in mol of iron per hour while increasing the pH to a final pH of 3.0 to 5.0 by adding enough alkaline component to raise the pH to a speed from 0.01 to 0.4 pH units / h; h) after step g), optionally continuing the oxidation while maintaining the pH at a constant value between 3.0 and 5.0; i) stopping oxidation when the Fe (II) content of the suspension of step g) or h) is less than 1 mol%; Y j) separating, washing, drying and grinding the iron oxide yellow pigment from step i).

8. A construction material, characterized in that it comprises the yellow pigment of iron oxide according to claims 1 or 7.

9. A process for coloring a building material, characterized in that it comprises adding the yellow pigment of iron oxide according to claims 1 or 7 to the construction material.

10. A paper or plastic material, characterized in that it comprises the yellow pigment of iron oxide according to claims 1 or 7.

11. A process for coloring the paper or plastic material, characterized in that it comprises adding the yellow pigment of iron oxide according to claims 1 or 7 to the paper or plastic material.

12. A paint or lacquer, characterized in that it comprises the yellow pigment of iron oxide according to claims 1 or 7.

13. A process for coloring a paint or lacquer, characterized in that it comprises adding the yellow pigment of iron oxide according to claims 1 or 7 to the paint or lacquer.

14. A coloring preparation, characterized in that it comprises the yellow pigment of iron oxide according to claims 1 or 7.

15. A process for producing a dye preparation, characterized in that it comprises adding the yellow pigment of iron oxide according to claims 1 or 7 to the dye preparation.