MXPA98009508A - Pigments of iron oxide yellow thermoes - Google Patents

Abstract

The present invention relates to the obtaining of pigments of yellow iron oxide with a silking index of less than 5 and a heat resistance for at least 5 minutes greater than 220 ° C in polyethylene by oxidation of metallic iron with nitrobenzene in a medium acid, in the presence of compounds of elements selected from main groups 3 and 4 of the periodic system

Description

IRON OXIDE YELLOW PIGMENTS THERMOSTABLE Field of Invention The present invention relates to pigments of iron oxide yellow with low silking and chromatically pure effect in the form of almost isometric particles and with high heat resistance.

Background of the Invention Iron oxide color pigments that are used as ecologically harmless colorants in ceramics, building materials, plastics, lacquers and paper can be obtained basically in shades of black, yellow, red and brown.

The iron oxide pigments are obtained as described in Ullmann's Encyclopaedia of Industrial Chemistry, VCH, Weinhei 1992, volume A20, page 298 et seq., By means of reactions REF. : 28845 in solid phase (red, brown and black pigments), precipitation reactions and hydrolysis of iron salts (yellow, red, orange and black pigments) as well as by the 'Laux process described in DE-A 463 773 Oxidation of iron with aromatic nitro compounds in the presence of polyvalent and hydrolysable salts (black and yellow pigments).

Natural and synthetic iron oxide yellow pigments are used for the coloring of building materials, lacquers, plastics and paper.

The chromatically pure, living, customary iron oxide yellow pigments are present as acicular pigment particles and due to their acicular shape have a reduced bulk density with respect to the isometric particles, which causes drawbacks in storage.

Compared with the isometric pigment particles in the acrylic pigment coatings suspensions, undesired viscosities are also observed. In addition, the required amount of binders of the acicular pigments is clearly greater than that of the isometric pigments.

Due to their acicular shape, the iron oxide yellow pigments that are ancestorized in lacquers and when incorporated into plastic sheets are oriented in a direction predominantly parallel to their acicular axis. Since its optical behavior (absorption and dispersion) is different in the direction of its acicular axis to the optical behavior at right angles to the acicular axis, different color impressions are obtained for the observer depending on whether the layer of lacquer or the colored sheet is viewed in the predominant direction or perpendicular to it. This undesired effect that is called "silking" ("silk") because it was observed first in silk fabrics, significantly limits the use of iron oxide yellow pigments.

The degree of silking of iron oxide yellow pigments can? reduce by mixing acicular iron oxide pigments with yellow isometric pigments such as nickelrutyl yellow. The nickelrutyl yellow pigments come out significantly more expensive than the iron oxide yellow pigments. Isomeric pigments such as nickelrutyl yellow do not naturally have any silking effect.

As the yellow iron oxide pigments are ecologically harmless and are cheap to prepare, it is basically required to carry out colorations as much as possible exclusively with pigments of yellow - iron oxide without using more expensive pigments such as nickelrutyl.

It is a drawback of iron oxide yellow pigments in addition to the observed silking effect, its insufficient heat resistance. The dissociation of the water bound in the goetite by thermal loading leads to the undesired brownish red coloring. Due to their low heat resistance, iron oxide yellow pigments common in the paper industry can not be used in many plastics systems, for example in the coloring of thermoplastic plastics or in the coil coating process. in lacquer applications.

As iron oxide yellow pigments have basically the advantages of greater environmental compatibility and lower production costs, there are numerous technical solutions to improve some of the above-mentioned inadequate properties of iron oxide yellow pigments.

For lacquering with iron oxide yellow pigments that require low viscosity and high chromatic purity as well as a small amount of binder, acicular iron oxide yellow pigments subsequently treated especially for the respective inorganic or organic binder system have been developed. These pigments certainly show reduced viscosities in the binder if a small amount of binder is required, but they are unsuitable for all lacquer suspensions in which their typical high silking effect is disturbing. t Pigments of chromatically pure, living iron oxide yellow, obtained from special germs, produced in the presence of compounds of elements B, Al, G "a, Si, Ge, Sn or Pb (DE-A 33 26 632), certainly have a sufficient lack of silking effect for the coloring of plastic sheets, but they are not sufficiently thermosetting for the coloring of plastics.

To improve the heat resistance of iron oxide yellow pigments, coating processes with metal phosphates have been proposed (DE-A 2 740 861 and US-A 4 053 325), with Al compound or hydrothermal syntheses (US Pat. A 4 376 677, JP-A 53 102 298, US-A 4 376 656). Pigments of iron oxide yellow are obtained with improved heat resistance, but due to other inconvenient properties, for example due to their high price, their low chromatic purity, their small coloring capacity and their marked silking effect, they can only be used in a limited way.

Thus, they are premises for the use of yellow pigments in the coloring of plastic sheets sufficient heat resistance, sufficient chromatic purity and chromatic intensity as well as absence of silking effect. The usual coated iron oxide yellow pigments can not be used here for their silking effect. The hydrothermally obtained thermodynamic iron oxide yellow pigments are not used for plastic sheets because of their high costs, their small chromatic intensity and their silking effect.

Products that have the properties of high gloss, high chromatic purity, low viscosity, little silking effect, little need of binder and high bulk density are not known until now.

Accordingly, until now for the iron oxide yellow pigments there are only technical solutions that improve certain disadvantageous properties of iron oxide yellow pigments such as silking or heat resistance.

Description of the invention.

The object of the present invention is therefore to provide chromatically pure, living, yellow iron oxide pigments with little silking effect, which have sufficient heat resistance for the coloring of plastic sheets.

Surprisingly it has been found that the desired iron oxide yellow pigments, comprising the aforementioned properties in a combination of properties hitherto not known, can be prepared by a modified nitrobenzene reduction process in the presence of compounds of the the main groups 3 and 4 of the periodic system.

The subject of the invention are iron oxide yellow pigments with a Fe content greater than 58% with a silking index of less than 5 chromatic values for the pure pigment tone of the luminance L * of 54 to 65 iCIELAB units, in the saturation C * from 38 to 65 CIELAB units with a red to * ratio of 8 to 15 CIELAB units, with a yellow ratio of 37 to 55 CIELAB units and a thermoresistance for at least 5 minutes greater than 220 ° C in polyethylene.

The proportion of yellow b * of the iron oxide yellow pigments according to the invention preferably ranges from 37 to 53 CIELAB units, the proportion of red preferably from 8 to 14 CIELAB units.

The heat resistance of the iron oxide pigments according to the invention is for at least 5 minutes preferably greater than 230 ° C, in particular higher than 240 ° C and particularly preferably greater than 250 ° C and in a spatial embodiment even greater than 260 ° C.

The silking index of the iron oxide pigments according to the invention is preferably less than 3, especially less than 2.

The bulk density of the iron oxide pigments according to the invention preferably reaches more than 0.5 t / m 3, especially more than 0.6 t / m 3.

The iron oxide pigments according to the invention preferably contain elements selected from the main groups 3 and 4 of the periodic system, in particular composed of aluminum, gallium, silicon or germanium, especially from 0.3 to 15% by weight, with special preference of 0.5 to 10% by weight, of aluminum compounds, calculated as A1203.

Another object of the present invention is a process for the preparation of iron oxide yellow pigments according to the invention in a process of iron solubilization by oxidation of metallic iron with nitrobenzene in acid medium, characterized in that the reaction is carried out carried out in the presence of compounds of elements selected from major groups 3 and 4 of the periodic system, preferably aluminum compound.

The proportion of the aluminum compounds is chosen so that the finished iron oxide pigment contains from 0.3 to 15% by weight, especially from 0.5 to 10% by weight of aluminum compound, calculated as A1203.

As the aluminum compound, a water-soluble aluminum salt, especially aluminum chloride, is preferably used.

The following examples will describe, by way of example, the preparation of chromatically pure iron oxide yellow pigments, with little silking and thermosetting effect, the person skilled in the art being able to choose the equipment or the additional materials to be used. use as needed.

The parts and percentages indicated in the following examples are referenced by weight, unless otherwise indicated.

Pure tone measurement The color evaluation of the pigments obtained according to the invention is carried out in Alkydal F 48 (Alkyd resin from Bayer AG) at a pigment concentration of 10%.

Alkydal F 48 is an alkyd semi-oleic resin, air drying, drying vegetable acid base, benzene for lacquers / xylene 38: 7 (with a non-volatile proportion of approximately 55% by weight), oil content / triglyceride in the non-volatile part: approximately 48%, phthalic anhydride in the non-volatile part: approximately 26%, Composition of a typical lacquer: 95.6% of Alkydal F 48 in benzene for lacquers / xylene (38: 7), 0.78% of 2-butanoxime at 55% in benzene for lacquers (agent against the formation of skin), 1.30% organic calcium salt in xylene (with 4% Ca) ®Octa Soligen Calcium 4 (wetting agent, Borchers AG), 0.22% organic xylene cobalt salt (with 6% Co) ®Octa Soligen Kobalt '6 (drying agent, Borchers AG), 0.87% organic zirconium salt in xylene (with 6% Cr) ®Octa Soligen Zirkonium 6 (adjuvant wetting agent, Brochers AG), 1.57% glycolic acid butylester (leveling improver).

The components were mixed with a rapid laboratory stirrer obtaining the finished lacquer. A disc paint preparation machine (Muller) was used, as described in DIN EN ISO 8780-5 (April 1995). An Engelsmann Jel 25/53 Muller with an effective disk diameter of 24 cm was used. The number of revolutions of the lower disk reached 75 min-1. By the weight of the upper disc and an additional weight of 2.5 kg in the loading bracket, the force between the discs reached approximately 0.5 k. 0.3 g of pigment and 2.00 g of lacquer were dispersed in a step at 100 revolutions according to the procedure described in DIN EN ISO 8780-5 (April 1995) section 8.1. The Muller device was opened and the fluid lacquer was collected in the lower disc outside the center. Then another 2.0 g of lacquer was added and the disks were reassembled. After two hours at 50 revolutions without additional weight the preparation is completed.

The pigmented lacquer was applied on a non-absorbent board with a suitable film extender (slot height of at least 150 μm, maximum 250 μm). The lacquered cardboard (the application) was then dried for at least 12 hours at room temperature in a low dusty place. Before the chromatic measurement the application was dried for one hour at about 65 ° C and cooled.

A spectrophotometer ("chromatic measuring device") with an Ulbricht ball and with the measurement geometry d / 8 without brightness trap is used. This measurement geometry is described in ISO 7724/2 - 1984 (E) point 4.1.1, in DIN 5033 part 7 (July 1983) point 3.2.4 and in DIN 53236 (January 1983) point 7.1 .1. A measuring device was used © Dataflash 2000 from Datacolor International.

The color measuring device was calibrated against a white ceramic working pattern, as described in ISO 7724 / 2-1984 (E) point 8.3. The reflection data of the working pattern are compared in the measuring device with an ideal matt white body, so that after calibration with the white working pattern all the chromatic measurements are referred to the ideal matt white body. The calibration of the black point is made with a black hollow body from the manufacturer of the measuring device.

The chromatic measurement is carried out immediately after the preparation of the test sample. A possible existing brightness trap mode is disconnected. The temperature of the measuring apparatus and the test sample reaches approximately 25 ° C ± 5 ° C.

The application is placed on the measuring device so that the measuring hole covers a central position of the coating layer. The application must be complete and flat. The measuring hole must be completely covered by the lacquer layer. Then proceed to the measurement.

From the measured reflection spectrum, according to the calculation instructions of ASTM E 308-1985, point 7, the CIÉ L *, a * and b * coordinates of 1976 are calculated. The weight functions of the standardized light type C and of the 2 ° -normal observer of 1931 are used in the ASTM E 308 - 1985 standard, Table 5.6. The region of wavelengths lies between 400 nm and 700 nm. The wavelength range reaches 20 nm. No brilliance is removed by calculation. The reference values obtained are converted according to DIN 5033, part 3 (July 1992) to the CIELAB color data system. silking index Preparation in an alkyd paste for measurement of silking index.

The pigment was prepared with a disc paint preparation machine (Muller) in a non-drying test binder. The test binder (paste) consists of two components: Component 1 Component 1 is an alkyd resin binder based on linseed oil and phthalic anhydride. It corresponds to the specification indicated in the standards DIN EN ISO 787-24: 1995, ISO 787-25: 1993 and DIN 55 983 (December 1983) as requirements for color pigments in a test binder. The product is used © Sacolyd L 640 (Krems Chemie), before © Alkydal 64 (Bayer AG).

Component 2 Component 2 is a rheological additive that is added to achieve a thixotropic behavior of the pulp. A hydrogenated castor oil modified pul veriform, © Luvothix HT (Lehmann &Voss &Co) at a concentration of 5% is used.

The Luvothix HT dissolves in the Sacolyd L 640 between 75 and 95 ° C. The cooled imperforable mis pd through a cold laminator. With this the pasta is ready.

For the preparation of the pigmented paste, a disc paint preparation machine (Muller) was used, as described in DIN EN ISO 8780-5 (April 1995). An Engelsmann Jel 25/53 Muller with an effective disc diameter of 24 cm was used. The number of revolutions of the lower disk reached 75 min-1. Due to the weight of the upper disc and an additional weight of 2.5 kg in the loading bracket, the force between the discs reached approximately 0.5 kN. 0.4 g of pigment and 5.00 g of paste were dispersed in two steps at 25 revolutions each according to the procedure described in DIN EN ISO 8780-5 (April 1995) section 8.1.

Then the pigment-paste mixture was spread on a disc of pastes that in its function corresponds to the disk of pastes of DIN 55983 (December 1983). The scraper belonging to the pasta disk was passed over the disk cavity filled with the pigment-paste mixture so that a smooth surface was formed. The scraper moved here in one direction with a speed of approximately 3 to 7 cm / s. By this preparation, the acicular particles optionally present in the pigment were oriented in the direction of the scratch. The smooth surface was measured within a few minutes.

The 8 / d measurement geometry used for measuring the silking effect is described in ISO 7724 / 2-1984 (E) point 4.1.1, in DIN 5033 part 7 (July 1983) point 3.2.1 and in DIN 53236 (January 1983) point 7.1.1. A Perkin Elmer Lambda 19 was used with an Ulbricht © Labsphere ball of 15 cm in diameter.

For the measurement, a commercially available linear film polarization filter of sufficient size was arranged outside the integration ball in the path of the lighting rays in a defined position, so that the direction of the E vector (electric field) of the lightning Light incident on the measuring point (sample orifice) is known. The filter has a degree of polarization of > 99% The trajectory of the reference beam remains unchanged without a filter.

The reference measuring hole of the integration ball is closed with a white opaline glass pattern that disperses diffusely. No brightness trap is used.

After installing the filter, another opaline glass pattern (work pattern) is placed in the sample hole and the measuring device is calibrated. The working pattern meets the requirements described in ISO 7724 / 2-1984 (E) section 8.3. The reflection data of the working pattern is compared by computer with an ideal white matte body, so that after calibration with the white working pattern all the chromatic measurements are referred to the ideal matt white body. The dark current in the black point was measured with a black hollow body, it was filed in the computer and was taken into account in the calibration of the measurement program.

The measurement was made immediately after sample preparation. The temperature of the color measuring apparatus (reflection spectrometer) and of the sample amounted to approximately 25 ° C ± -5 ° C.

The sample was measured in two positions perpendicular to each other with respect to the polarization filter: Measurement i i The pigment particles are oriented with their longest axis parallel to the vector E of the illumination. The scanning direction of the doctor blade is parallel to the vector E.

Measurement Y2_L: The pigment particles are with their longest axis oriented largely perpendicular to the vector E of the illumination. The scanning direction of the doctor blade and that of the vector E are perpendicular to each other.

A device for rotating the sample 90 ° C is very useful but not essential if suitable marks are applied in the sample hole.

From the measured reflection spectra, the standardized "Y" chromatic values are calculated according to the calculation instructions of ASTM E 308 - 1985, point 7. The weight functions of the standardized light type C and the second one are used -observer normal of 1931 in Table 5.6. The region of wavelengths lies between 400 nm and 700 nm. The wavelength range reaches 20 nm. No brilliance is removed by calculation.

The SAI silking index is calculated from the normalized "Y" color values: SI = (1-Yi |, / Y2) *? Oo The result is rounded to a whole number.

An SI close to zero indicates the absence of silking effect, while an SI > About 5 indicates a pigment that produces silking effect.

Heat resistance The determination of the heat resistance can be carried out according to the procedures described below.

Procedure A: The heat resistance of the yellow pigment can be determined in a simple manner by subjecting the pigment to a thermal load in an oven with recirculation of air. The amount of sample in porcelain capsules should reach 5 g, the residence time at the test temperature 30 minutes. As the lowest test temperature, 160 ° C was chosen and the test temperature increased in 10 ° C intervals. The temperature at which the pigment being tested showed a clear change towards red was determined for the first time. In addition, a color evaluation of all heat-treated samples can be carried out. As a reference, the dry sample of the coated yellow pigment is chosen. The chromatic tones of the thermally treated samples were determined in the Alkydal F 48 binder at a pigment volume concentration of 10% according to DIN 6174 (equivalent to ISO / DIN 7724, versions 1-3). Since a color change of the yellow to red pigment is not desired, the chromatic distances Da * (a * - proportion of red) of the pigment samples are calculated according to DIN 6174 against the reference (dry sample of the yellow pigment coated). The test temperature rounded to 10 ° C at which a chromatic distance Da * = 3 is produced with respect to the reference, gives the yellow pigment resistance thermometer.

Procedure B: In addition, for testing the yellow pigment heat resistance, DIN 53 772 can be used: dye test on thermoplastic plastics. Determination of the thermoresistance by injected cast iron.

The determination of the heat resistance is carried out according to DIN 53772. i 10 g of the yellow pigment to be tested were mixed in a glass bottle on a roller support for 20 minutes with 1 kg of high density granules without coloring from a polyethylene thermoplastic plastic, © Vestolen A6016 (Chemische erke Hüls AG). The mixture was then treated in a twin screw extruder with granulation device to obtain a homogeneously colored test granulate. The test granulate was dried for 4 hours at 70 ° C.

The preparation of the test pieces in the form of colored plates, for the determination of the heat resistance (flat surface, minimum 2.5 mm thickness, for adequate measurement) was carried out with a screw type injected smelting machine © Arburg 200 Allraunder, firm Arburg, Loßburg, with cast iron mold. The content of the plunger of the screw provides 5 specimens. The injection molding machine has an electric thermometer device with a temperature sensor for measuring the temperature in the melt. The machine is filled with test granulate and heated to 200 ° C. In this way, 12 plates (test tubes) were injected and discarded. Upon reaching 200 ° C, 5 plates were injected and numbered as test pieces 1 to 5. These served as comparison or reference samples for the following temperature steps. The test or injection temperature was then raised in intervals of 20 ° C (or 10 ° C). During the thermal rise at each respective subsequent test temperature, 6 plates were injected and discarded. Once the temperature was reached, the injection cycle was interrupted and the molten mass, and consequently also the iron oxide yellow pigment contained therein, was charged for 5 minutes at that temperature. Then, 5 plates (specimens) were injected and numbered. Then the next higher temperature was adjusted in the same way and the operation was repeated (5 minutes of thermal load, then injection of 5 test pieces). The test temperature was further increased from 20 to 20 ° C (or 10 to 10 ° C) until it became clear that striae formation or change of red coloration in the specimens could be observed. For determining the resistance thermometer, plates 2 and 3 were taken and purchased with the specimens injected at 200 ° C.

A simple visual determination is possible. The highest possible injection temperature is determined at which the sample plates do not show any stria and show no change in color to red compared to the specimens injected at 200 ° C. The specimens were tested according to DIN 53 772 (determination of the heat resistance by injection molding) colorimetrically according to DIN 53 236 and DIN 6174 to see the difference in color with respect to the specimens produced at the lowest test temperature (200 ° C). C). According to DIN 53 722 the resistance thermometer is the test temperature at which a color difference of DE * to b = 3 results between the test pieces, referred to the test medium (polyethylene, Vestolen A 6016). The chromatic distances of the specimens with respect to the reference are represented in a diagram according to the test temperature in ° C. By means of graphic interpolation, the test temperature in ° C is determined at which the chromatic distance reaches dE * a b = 3, and this value is rounded to 10 ° C. This is valid according to DIN 53 772 as a measure of the heat resistance of the pigment in the chosen plastic.

Procedure C: The thermoresistance can also be determined using the procedure according to DIN 53 775 part 2, October 1990, testing of dyes in molding compositions of PVC Determination of the oil index according to ISO 787 part 5 Working devices: Analytical balance 300 x 400 mm glass plate Cutting spatula 10 ml Burette Reagents Flaxseed oil with an acid number of 5.0-7.0 mg / 9 g of KOH Sample preparation: The exact sample quantity, a) pigment red, black, brown: 4 g b) yellow pigment: 2 g It was put on the glass plate. The linseed oil was added slowly and dropwise from the burette. After each addition the oil was mixed with the pigment with the cutting spatula. The oil addition was extended until a putty type paste was formed. The paste should be divided again on the glass plate without cracking, forming lumps or streaks. The oil addition should last approximately 10 to 15 minutes. The amount of oil consumed was noted.

Calculation: IA = oil index of the sample: oil consumption in grams per 100 g of iron oxide yellow pigments Oil density: 0.93 g / ml C = amount of oil consumed in g m = mass of the sample in g IA = 0.93 x 100 x C M Apparent density Working devices: Balance, precision 0.1 g Test tube 500 ml Sieve, mesh width 500 μ Realization A sufficient amount of pigment was sieved for 500 ml of sieved material through a 500 μm sieve. 500 ml of this was added to a previously weighed sample and weighed. The operation must be done without jerks or vibrations. The determination was made in duplicate. The result was calculated by forming the mean value from the individual data.

Calculation Dap = M / 500 Dap = bulk density in g / ml 500 = volume in my M = mass in g The iron oxide pigments obtained by reaction of metallic iron raw materials with nitrobenzene are prepared according to the Laux process, which is described in DE-C 463 773, DE-C 464 561 and DE-C 515 758 By varying substances that are used additionally, the person skilled in the art can determine the iron oxide phases (α-FeOOH, Y-Fe203, α-Fe203 or Fe30) obtained in the Laux process. According to the procedure described in the Examples in DE-C 463 773, the following substances were reacted in vessels and reactors equipped with agitators: t * from start of dosing to end of dosing l: 0 min = Achievement of the reduction temperature of 97 ° C = boiling temperature, reflux. In the tests n ° 8 to 10, 15 minutes later Carrying out the tests 1 to 5 Description of the reaction apparatus Apparatus: 2 2 1 cups with flat grinding with flat ground grinding with 4 NS 29 grinding, Centelen flat grinding joint, tightening ring, intensive reflux condenser, Claisen supplement, PTFE bellows, 2 metering pumps © ProMinent (Fa.ProMinent, Heidelberg) for nitrobenzene and drinking water with 500 ml drip funnel as pumping chamber, Universal agitator transmission LABC, 3 step arms with © Teflon brushes, arranged at 75 °, Agitator drive (IKA, RW 27 or RW 28, Fa.IKA, Staufen), Heating device ® Ceran (Schott Geráte GmbH, Hofheim) with oil bath (silicone oil P300, Bayer AG), Temperature regulator (Julabo Labortechnik, Seelbach] with Pt 100 measuring sensor, PTFE bottom supports for the cup with flat grinding in the oil bath.

Assembly: The sealing ring is placed in the flat grinding cup, the agitator is inserted and the lid is fastened with the clamping ring. The NS grinds are supplied with Teflon bushes and the agitator transmission is placed. In the assembly, care must be taken that the flat grindings are exactly on top of each other and that the agitator is centered. The appliance is placed in the oil bath on the PTFE bottom supports (height of the oil bath 10 cm above the bottom supports), with a forward grinding, with double tightening of the appliance. The agitator is fixed, with a distance to the bottom of the lower stirring blade of 2 to 3 mm. The Pt 100 measuring sensor is introduced into the oil bath with the tip of the sensor above the bottom of the flat grinding cup. Finally, the refrigerator is placed on top with the Claisen supplement and the PTFE bellows. The dosage injection of nitrobenzene and water is applied during the course of the test.

Realization Preparation The necessary reagents according to the Table, solution of aluminum chloride, iron, water and nitrobenzene, are prepared and the pumping chambers are filled. Shot blasting of the firm »Vulkan, Hattingen, with a content of C and Si of respectively, is used as a steel shot. 1% by weight and a proportion of > 40% by weight of particles with a diameter of 1 to 2 mm. Gray castings with a proportion of " castings are used as castings. 60% of the screening fraction from 1 to 2 mm. The cooling water is adjusted. With stirring between 250 and 400 rpm, the container is filled in the order indicated at room temperature. This is heated to the temperature of the oil bath of 90 ° C.

Route When the nominal temperature is reached, the dosing is started according to the prescribed. The dosing of the steel chips / grit during loading is done in ten partial quantities of equal magnitude that were added every 10 minutes.

Finishing: After all the additions have been completed, stirring is allowed 60 more minutes, then the transformation of nitrobenzene into aniline is checked. To do this, take a small amount of paste (raw aniline) with a spatula and put it in a glass beaker. The paste is digested with 5 ml of tert-butyl methyl ter. With a disposable syringe approximately 2 ml of the ether phase was taken and pressurized through a disposable PTFE filter to a CG test tube. Next, he chrooted the sample. If the reaction is incomplete, stir and / or add additional iron.

Processing: When a 100% transformation is achieved, the pigment paste is cooled. 250 to 300 g of the pigment paste are taken from the flat grinding cup for processing. The pigment is washed to leave it free of salts and aniline, the residual iron is screened, filtered through a filter plate and dried.

Carrying out the tests 6 + 7 Reaction vessel, nominal volume of 89 1 with: Drive motor with continuous adjustment, 2 stirrers with stepped cross arms, with the lower leaf adjusted to 30 ° C, with upward flow, Steam-wrapped heating with temperature regulator, Refrigerator glass, ProMinent dosing pump for nitrobenzene, ProMinent dosing pump for service water. Preparation: The necessary reagents according to the Table, solution of aluminum chloride, iron, acids and t water, are separated and the pumping chambers are filled. The cooling water is adjusted. The materials described in tests 1 to 5 are used as steel shot and gray cast iron.

Stirring at 175 rpm. Fill the container in the order indicated at room temperature. This is heated to the temperature indicated in the Table.

Course: When the nominal temperature is reached, the dosage is started according to the prescribed. Here, the iron was distributed in 6 equal portions every 10 minutes.

Finalization: After all the additions have been completed, stirring is allowed 60 more minutes, then the total transformation of nitrobenzene into aniline is checked. The pulp is then processed as described in tests 1 to 5.

Carrying out of tests 8 to 10 The tests were carried out in the technical devices described in tests 7 and 8 using the amounts indicated in the Table in the manner described above.

Table 2: Product data. of the Examples and Comparative Examples A = RBayfcrrox 420, B = RBayferrox 415, C = RBayfertox 915 (Bayer AG); D = "M? PICO 1000 I IRA (Columbian Co.) E = 87.5% mixture of" Lichtgelb 3 R (Baycr? G) / 12.5% of RBayfcrrox 420 (Baycr AG) * Determination of the thermoresistance in thermoplastic plastic "Vestolen A 6016 It is noted that in relation to this date the best method known by 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, the content of the following is claimed as property.

Claims (19)

Claims

1. Iron oxide yellow pigments, characterized in that they have: a) a Fe content greater than 58%; b) a Silking Index less than 5; c) color values at a pigment volume concentration of 10% in the test lacquer for the pure tone of the pigment in the luminance L * from 54 to 65 CIELAB units, in the saturation C * from 38 to 65 CIELAB units with a proportion of red to * from 8 to 15 CIELAB units, with a yellow ratio of 37 to 55 CIELAB units; and d) a resistor for at least 5 minutes greater than 220 ° C in polyethylene.

2. Iron oxide yellow pigments according to claim 1, characterized in that the proportion of yellow B * reaches 37 to 53 CIELAB units and the red ratio of 8 to 14 CIELAB units.

3. Iron oxide yellow pigments i according to claim 1, characterized in that the temperature of the liquor for at least 5 minutes is greater than 260 ° C.

4. Iron oxide yellow pigments according to claim 1, characterized in that the silking index is less than 3.

5. Iron oxide yellow pigments according to claim 1, characterized in that the bulk density is greater than 0.5 g / ml.

6. A method for processing pigments under temperature conditions greater than 200 ° C, characterized in that it comprises adding the iron oxide yellow pigment according to claim 1 of the process.

7. A thermoplastic coloration characterized in that it comprises the pigments of iron oxide yellow according to claim 1.

8. A thermoplastic coloring method characterized in that it comprises adding the iron oxide yellow pigments according to claim 1 for thermoplastic.

9. A colored laminated paper, characterized in that it comprises the iron oxide yellow pigment according to claim 1.

10. A laminated paper coloring method characterized in that it comprises adding the iron oxide yellow pigments according to claim 1 for laminated paper.

11. A colored building material characterized in that it comprises the iron oxide yellow pigment according to claim 1.

12. A method of coloring materials for construction characterized in that it comprises adding the iron oxide yellow pigment according to claim 1 for construction material.

13. The coloration of lacquers characterized in that it comprises the iron oxide yellow pigments according to claim 1.

14. A lacquer coloring method characterized in that it comprises adding the iron oxide yellow pigments according to claim 1 for the lacquers.

15. A powder coloration characterized in that it comprises the iron oxide yellow pigments according to claim 1.

16. A powder coating coloration method characterized in that it comprises adding the iron oxide yellow pigments according to claim 1 for powder coatings.

17. An enamel coloration characterized in that it comprises the iron oxide yellow pigments according to claim 1.

18. A glaze coloring method characterized in that it comprises adding the iron oxide yellow pigments according to claim 1 for enamels.

19. A process for producing the iron oxide yellow pigments according to claim 1 in an iron solvent process, the process characterized in that it comprises: a) oxidizing a metallic iron with nitrobenzene in an acid medium; and b) carrying out the oxidation in the presence of elements chosen from the main groups 3 and 4 of the Periodic Table.