COLOUR-STRONG MANGANESE FERRITE COLOUR PIGMENTS

Abstract

The present invention relates to strongly coloured manganese ferrite colour pigments, to the production thereof and to the use thereof.

Claims

1. Manganese ferrite black pigments having a content of MnO of 5.0% to 40.0% by weight and a content of phosphate of 1.5% to 3.0% by weight, that have a blending ratio for the depth of shade value B 1/9 in accordance with DIN 53235 Part 1 and 2 of >−12.0.

2. The manganese ferrite black pigments according to claim 1, wherein the pigments have a content of MnO of 8.0% to 35.0% by weight.

3. The manganese ferrite black pigments according to claim 1, wherein the pigments have a content of phosphate of 1.5% to 2.0% by weight.

4. The manganese ferrite black pigments according to claim 1, wherein the pigments have a blending ratio for the depth of shade value B 1/9 in accordance with DIN 53235 Part 1 and 2 of −10.0 to −6.0.

5. The manganese ferrite black pigments according to claim 1, wherein the colour strength of the pigments is from 40% to 120% stronger with respect to manganese ferrite colour pigments that have a phosphate content of <0.5%.

6. Process for producing a manganese ferrite black pigment according to claim 1, wherein oxidic or oxide-forming starting materials of the iron and manganese are mixed with one another with addition of alkali metal salts and organic and/or inorganic phosphates, and the mixture is then calcined at temperatures above 600° C. where the calcining atmosphere has an oxygen content of 7% to 25%.

7. Process for producing a manganese ferrite black pigment according to claim 6, wherein the content of MnO is from 5% to 40% by weight; the content of Fe, calculated as Fe.sub.2O.sub.3, is from 50.0% to 95.0% by weight; and the content of phosphate is from 1.5% to 3.0% by weight, where the sum total of MnO, Fe.sub.2O.sub.3 and phosphate must not be above 100% by weight.

8. Process for the colouring of inorganic or organic dispersions, of products of the paint, lacquer, coating, building materials, plastics and paper industries, in food, and in products of the pharmaceutical industry such as tablets, wherein the manganese ferrite black pigments according to claim 1 are utilized.

9. The manganese ferrite black pigments according to claim 1, wherein the blending ratio for the depth of shade value B 1/9 in accordance with DIN 53235 Part 1 and 2 is >−10.0.

10. The manganese ferrite black pigments according to claim 1, wherein the pigments have a content of phosphate of 1.7% to 1.8% by weight.

11. The manganese ferrite black pigments according to claim 1, wherein the colour strength of the pigments is from 90% to 115% stronger, with respect to manganese ferrite colour pigments that have a phosphate content of <0.5%.

12. The process according to claim 6 for producing a manganese ferrite black pigment according to claim 1, wherein oxidic or oxide-forming starting materials of the iron and manganese are mixed with one another with addition of alkali metal salts and organic and/or inorganic phosphates, and the mixture is then calcined at temperatures above 700° C., where the calcining atmosphere has an oxygen content of 7% to 25%.

13. The process according to claim 7 for producing a manganese ferrite black pigment according to claim 6, wherein the content of MnO is from 8.0% to 35.0% by weight; the content of Fe, calculated as Fe.sub.2O.sub.3, is from 65.0% to 90.0% by weight; and the content of phosphate is from 1.5% to 2.0% by weight, where the sum total of MnO, Fe.sub.2O.sub.3 and phosphate must not be above 100% by weight.

Description

EXAMPLES

[0025] I. Description of the Measurement Methods Used

[0026] A. Determination of the Iron Content and Manganese Content

[0027] The iron content and the manganese content were measured by acid digestion and potentiometric titration. An introduction to electrochemical analysis methods—which also include potentiometric titration—can be found by way of example in “Taschenatlas der Analytik”, G. Schwedt, Thieme-Verlag 1996, ISBN 3-527-30870-9 p. 50 ff. The measurement method has a determination accuracy of 0.2% by weight.

[0028] B. Measurement of the Colour Values in L64Thix, Lightening

[0029] The pigment was prepared using a muller in a non-drying test binder. The test binder (paste) is composed of two components:

[0030] Component 1

[0031] SACOLYD® L640 (Krems Chemie AG, Austria, alkyd resin binder based on linseed oil and phthalic anhydride) (formerly ALKYDAL® L64 (Bayer AG, DE)). It corresponds to the specifications given in standards DIN EN ISO 787-24 (October 1995), ISO 787-25:1993 and DIN 55983 (December 1983) as requirements for a test binder for colour pigments.

[0032] Component 2

[0033] LUVOTHIX® HT (Lehmann & Voss & Co., Germany, pulverulent, modified, hydrogenated castor oil) as rheological additive which is added for the thixotroping of the paste. It was used in a concentration of 5.0% by weight, based on Component 1.

[0034] Component 2 was dissolved in Component 1 at 75-95° C. The cooled, compact mass was passed once through a triple-roll mill. The L64 paste was then complete. Use was made of a plate-type paint dispersing machine (muller), as described in DIN EN ISO 8780-5 (April 1995). Used was an ENGELSMANN JEL 25/53 muller with an effective plate diameter of 24 cm. The speed of the lower plate was approx. 75 min.sup.−1. The force between the plates was set at approx. 0.5 kN by hanging a 2.5 kg loading weight on the loading bracket.

[0035] The lightener used was a commercial titanium dioxide pigment, TRONOX® R-KB-2, Kerr-McGee Corp., US (formerly BAYERTITAN® R-KB-2 (Bayer AG, DE)). The composition of R-KB-2 corresponds to type R 2 in ISO 591-1977. 0.4 g of pigment to be tested, 2.0 g of TRONOX® R-KB-2 and 3.0 g of paste were dispersed in five stages of 25 revolutions each by the process described in DIN EN ISO 8780-5 (April 1995) Section 8.1.

[0036] The pigment/paste mixture was then spread into a paste plate, the function of which corresponds to the paste plate in DIN 55983 (December 1983). The doctor blade belonging to the paste plate is drawn over the indentation in the plate that is filled with the pigment/paste mixture, so that a smooth surface is produced. This doctor blade is moved in one direction at a speed of approx. 3-7 cm/s. The smooth surface is measured within a few minutes.

[0037] C. Colorimeter

[0038] A spectrophotometer (“colorimeter”) having the d/8 measurement geometry without a gloss trap was used. This measurement geometry is described in ISO 7724/2-1984 (E), Section 4.1.1, in DIN 5033 Part 7 (July 1983), Section 3.2.4 and in DIN 53236 (January 1983), Section 7.1.1.

[0039] Used was a DATAFLASH® 2000 measuring device (Datacolor International Corp., USA). The colorimeter was calibrated against a white, ceramic working standard, as described in ISO 7724/2-1984 (E) Section 8.3. The reflection data of the working standard against an ideally matt-white body are stored in the colorimeter so that, after calibration with the white working standard, all colour measurements are related to the ideally matt-white body. The black-point calibration was carried out using a black hollow body from the manufacturer of the colorimeter.

[0040] D. Colour Measurement

[0041] The result of the colour measurement is a reflection spectrum. It is possible to calculate any desired colorimetric parameter from the reflection spectrum. The colorimetric parameters used in this case are calculated in accordance with DIN 6174 (CIELAB values).

[0042] Any gloss trap present is switched off. The temperature of the colorimeter and test specimen was approx. 25° C.±5° C.

[0043] E. Colour Strength

[0044] The colour values are stated according to the above-described measurement in accordance with DIN 6174 (CIELAB values). The relative colour strength of the measured colour pigment in relation to a comparative pigment (in the given case: comparative pigment) also results from the measurement in the lightening. The comparative pigment has a colour strength of 100%.

[0045] In order to state an absolute characteristic value from these relative figures, the so-called “blending ratio” was calculated. The blending ratio was determined in accordance with DIN standard 53235 Part 1 and Part 2 from 1974 for the depth of shade value B 1/9. The blending ratio illustratively indicates the ratio of a colour-imparting substance to a mixing component (in the given case: TiO.sub.2) which is used to achieve a defined depth of shade (depth of colour) in accordance with DIN standard 53235 Part 1 and 2 from 1974. A high blending ratio means that the same depth of colour can be achieved using less pigment. Such a pigment therefore has a stronger colour in practical use. A blending ratio for the depth of shade value B 1/9 in accordance with DIN 53235 Part 1 and 2 of greater than −10 corresponds to a colour strength that is at least 45% higher than the comparative pigment.

[0046] F. Other Devices

[0047] The stirring unit used was an Ultraturrax stirrer.

[0048] Suitable calcining apparatuses are common furnaces (for example muffle furnace, rotary flame furnace, rotary furnaces etc.) as long as the oxygen content in the calcining space is from 5% to 25%.

[0049] Suitable grinding units are all common comminution units for inorganic pigments, such as vibratory disc mills, classifier mills or jet mills.

II. Example 1

[0050] The properties of the starting materials iron oxide (Fe.sub.3O.sub.4), manganese oxide (MnO.sub.2) and sodium chloride correspond to the requirements from DE 1 767 868 A1 Example 1.

[0051] 321.5 g of an Fe.sub.3O.sub.4 suspension having a content of 31.1% by weight of Fe, calculated as Fe.sub.2O.sub.3, are admixed with 14 g of manganese(IV) oxide (manganese content: 67.3% by weight, calculated as MnO), 2.3 g of sodium chloride and 2.8 g of sodium tripolyphosphate, intimately mixed using a suitable stirring unit and filtered off with suction on a suction filter, the filter cake is dried at 240° C., homogenized in a mortar and then calcined at 800° C. for 15 minutes, homogenized again in a mortar and calcined at 800° C. for a further 25 minutes. The resulting pigment is then ground in a suitable device.

[0052] The pigment formed has a colour strength of 146% in relation to the comparative pigment. The blending ratio for depth of shade value B 1/9 is −9.7.

[0053] In contrast, the pigment in Comparative Example 1, which was calcined without being doped with phosphate, only has a colour strength of 75% in relation to the comparative pigment, which corresponds to a blending ratio of −17.2.

III. Example 2

[0054] The properties of the starting materials iron oxide (Fe.sub.3O.sub.4), manganese oxide (MnO.sub.2) and sodium chloride correspond to the requirements from DE 1 767 868 A1 Example 1.

[0055] 321.5 g of an Fe.sub.3O.sub.4 suspension having a content of 31.1% by weight of Fe, calculated as Fe.sub.2O.sub.3, are admixed with 22 g of manganese(IV) oxide (manganese content: 67.3% by weight, calculated as MnO), 2.3 g of sodium chloride and 3.0 g of sodium tripolyphosphate, intimately mixed using a suitable stirring unit and filtered off with suction on a suction filter, the filter cake is dried at 240° C., homogenized in a mortar and then calcined at 800° C. for 15 minutes, homogenized again in a mortar and calcined at 800° C. for a further 25 minutes. The resulting pigment was then ground in a suitable device.

[0056] The pigment formed has a colour strength of 168% in relation to the comparative pigment. The blending ratio for depth of shade value B 1/9 is −8.0.

[0057] In contrast, the pigment in Comparative Example 2, which was calcined without being doped with phosphate, only has a colour strength of 79% in relation to the comparative pigment, which corresponds to a blending ratio of −16.5.

IV. Example 3

[0058] The properties of the starting materials iron oxide (Fe.sub.3O.sub.4), manganese oxide (MnO.sub.2) and sodium chloride correspond to the requirements from DE 1 767 868 A1 Example 1.

[0059] 321.5 g of an Fe.sub.3O.sub.4 suspension having a content of 31.1% by weight of Fe, calculated as Fe.sub.2O.sub.3, are admixed with 31 g of manganese(IV) oxide (manganese content: 67.3% by weight, calculated as MnO), 2.3 g of sodium chloride and 3.1 g of sodium tripolyphosphate, intimately mixed using a suitable stirring unit and filtered off with suction on a suction filter, the filter cake is dried at 240° C., homogenized in a mortar and then calcined at 800° C. for 15 minutes, homogenized again in a mortar and calcined at 800° C. for a further 25 minutes. The resulting pigment was then ground in a suitable device.

[0060] The pigment formed has a colour strength of 177% in relation to the comparative pigment. The blending ratio for depth of shade value B 1/9 is −7.3.

[0061] In contrast, the pigment in Comparative Example 3, which was calcined without being doped with phosphate, only has a colour strength of 86% in relation to the comparative pigment, which corresponds to a blending ratio of −15.6.

V. Example 4

[0062] The properties of the starting materials iron oxide (Fe.sub.3O.sub.4), manganese oxide (MnO.sub.2) and sodium chloride correspond to the requirements from DE 1 767 868 A1 Example 1.

[0063] 321.5 g of an Fe.sub.3O.sub.4 suspension having a content of 31.1% by weight of Fe, calculated as Fe.sub.2O.sub.3, are admixed with 41.5 g of manganese(IV) oxide (manganese content: 67.3% by weight, calculated as MnO), 2.3 g of sodium chloride and 3.3 g of sodium tripolyphosphate, intimately mixed using a suitable stirring unit and filtered off with suction on a suction filter, the filter cake is dried at 240° C., homogenized in a mortar and then calcined at 800° C. for 15 minutes, homogenized again in a mortar and calcined at 800° C. for a further 25 minutes. The resulting pigment was then ground in a suitable device.

[0064] The pigment formed has a colour strength of 184% in relation to the comparative pigment. The blending ratio for depth of shade value B 1/9 is −6.7.

[0065] In contrast, the pigment in Comparative Example 4, which was calcined without being doped with phosphate, only has a colour strength of 88% in relation to the comparative pigment, which corresponds to a blending ratio of −15.3.

VI. Example 5

[0066] The properties of the starting materials iron oxide (Fe.sub.3O.sub.4), manganese oxide (MnO.sub.2) and sodium chloride correspond to the requirements from DE 1 767 868 A1 Example 1.

[0067] 161 g of an Fe.sub.304 suspension having a content of 31.1% by weight of Fe, calculated as Fe.sub.2O.sub.3, are admixed with 38.0 g of manganese(IV) oxide (manganese content: 67.3% by weight, calculated as MnO), 1.5 g of sodium chloride and 2.0 g of sodium tripolyphosphate, intimately mixed using a suitable stirring unit and filtered off with suction on a suction filter, the filter cake is dried at 240° C., homogenized in a mortar and then calcined at 800° C. for 15 minutes, homogenized again in a mortar and calcined at 800° C. for a further 25 minutes. The resulting pigment was then ground in a suitable device.

[0068] The pigment formed has a colour strength of 167% in relation to the comparative pigment. The blending ratio for depth of shade value B 1/9 is −7.7.

[0069] VII. Comparative Pigment

[0070] The properties of the starting materials iron oxide (Fe.sub.3O.sub.4), manganese oxide (MnO.sub.2) and sodium chloride correspond to the requirements from DE 1 767 868 A1 Example 1.

[0071] 161 g of an Fe.sub.304 suspension having a content of 31.1% by weight of Fe, calculated as Fe.sub.2O.sub.3, are admixed with 38 g of manganese(IV) oxide (manganese content: 67.3% by weight, calculated as MnO), 1.5 g of sodium chloride and without sodium tripolyphosphate, intimately mixed using a suitable stirring unit and filtered off with suction on a suction filter, the filter cake is dried at 240° C., homogenized in a mortar and then calcined at 800° C. for 15 minutes, homogenized again in a mortar and calcined at 800° C. for a further 25 minutes. The resulting pigment was then ground in a suitable device.

[0072] The pigment formed is used as comparative pigment for the examples described above. Its colour strength is set at 100%. The blending ratio for depth of shade value B 1/9 is −14.0.

TABLE-US-00001 TABLE 1 % by % by % by Colour Blending weight weight weight strength ratio Example Fe Mn PO.sub.4 in % B 1/9 1 89.81 8.46 1.73 146 −9.7 C 1  91.39 8.61 — 75 −17.2 2 85.57 12.67 1.76 168 −8.0 C 2  87.11 12.89 — 79 −16.5 3 81.30 16.96 1.73 177 −7.3 C 3  82.74 17.26 — 86 −15.6 4 76.80 21.45 1.74 184 −6.7 C 4  78.16 21.84 — 88 −15.3 5 65.01 33.12 1.79 167 −7.7 Comparative 66.20 33.80 — 100 −14.0 pigment

TABLE-US-00002 TABLE 2 Increase in colour strength with respect to % by % by % by Colour comparative weight weight weight strength example Example Fe Mn PO.sub.4 in % in % 1 89.81 8.46 1.73 146 94.7 C 1  91.39 8.61 — 75 2 85.57 12.67 1.76 168 112.7 C 2  87.11 12.89 — 79 3 81.30 16.96 1.73 177 105.8 C 3  82.74 17.26 — 86 4 76.80 21.45 1.74 184 109.1 C 4  78.16 21.84 — 88