METHOD FOR PREPARING PEARLESCENT PIGMENT FROM ILMENITE HYDROCHLORIC ACID ACIDOLYSIS SOLUTION BY CO-EXTRACTION

Abstract

A preparation method of pearlescent pigment coating materials is provided. The method of the present invention lies in that titanium-iron ions in ilmenites are dissolved by using a hydrochloric acid at a certain temperature and pressure, and then ferrous chloride in the acidolysis solution is precipitated by adding hydrogen chloride gas, the remaining titanium-iron ions are separated from other colored ions by means of co-extraction using an extractant upon oxidation, and an enriched titanium oxydichloride solution and ferrous hydrous oxide are obtained by employing a fractional back extraction and enrichment method, the titanium oxydichloride solution can be used for mica-titanium based pearlescent pigment coating materials, and can also be used for preparing titanium dioxide; and the acidified ferrous hydrous oxide and the oxidized ferrous chloride can be used as iron based pearlescent pigment coating materials or used for preparing iron oxide pigments.

Claims

1. A method for preparing pearlescent pigments comprising a ferric oxide (Fe.sub.2O.sub.3) coating layer or a titanium dioxide (TiO.sub.2) coating layer or a Fe.sub.2O.sub.3/TiO.sub.2 coating layer from ilmenites by using co-extraction, the method comprises the following steps: (1) adding hydrochloric acid and ilmenite into a reaction kettle according to a hydrochloric acid/ilmenite mass ratio of 0.5-15:1, raising the temperature to an elevated temperature T1 within a range of 30-95° C. under stirring, and then reacting at the reaction temperature T1, wherein hydrogen chloride gas is introduced in the reaction process, and the system is kept at the pressure P higher than the atmospheric pressure; directly filtering the reaction mixture after completion of the reaction to obtain a filtrate, cooling the filtrate, and carrying out solid-liquid separation to obtain a hydrochloric acid solution A0 containing titanium-iron ions and a ferrous chloride precipitate C0, and then, optionally, directly calcining the clean ferrous chloride precipitate C0 obtained by centrifugation to obtain iron oxide red pigments C1, or oxidizing the precipitate C0 by using an oxidant to obtain a ferric trichloride product C2, and then dissolving the ferric trichloride product C2 in water to obtain a ferric trichloride solution III; (2) adding the hydrochloric acid solution A0 containing titanium-iron ions obtained in the step (1) into a co-extractor, carrying out one-stage or multistage extraction by using a co-extractant, combining the extracts as an organic phase in all stages to obtain an iron-titanium enriched extract liquid, namely an organic phase A1, wherein the remaining aqueous phase after the one-stage or multistage extraction is a high-acidity raffinate with variegated ions Mn, V and Cr and containing no iron and titanium irons, namely an aqueous phase B 1; (3) adding the iron-titanium enriched extract liquid A1 into a titanium back extractor, back extracting the titanium ions by using a titanium back extractant to obtain an organic phase A2 containing iron ions and a raffinate I as an aqueous phase containing titanium oxydichloride, referred to as a solution I containing titanium oxydichloride; (4) adding the organic phase A2 containing iron ions into an iron back extractor, back extracting iron with water to obtain a purified ferric trichloride solution II, and optionally, treating the ferric trichloride solution II by using an alkali precipitation method or a hydrothermal method to obtain iron oxide red pigments; and returning the remaining organic phase to the co-extractor in the step (2); and (5) sheet substrate coating step: coating sheet substrate raw materials or secondary sheet substrates with a ferric oxide (Fe.sub.2O.sub.3) coating layer or a titanium dioxide (TiO.sub.2) coating layer or a Fe.sub.2O.sub.3/TiO.sub.2 coating layer by using the ferric trichloride solutions II and/or III, and/or using the titanium oxydichloride solution I in the step (3).

2. The method according to claim 1, wherein the ilmenite in the step (1) are titanium concentrates, high titanium slags or modified titanium concentrates, wherein the modified ilmenite concentrate is the ilmenite concentrate subjected to oxidizing roasting and reduction roasting.

3. The method according to claim 1, wherein the pressure P in the step (1) is within the range of 0.102-2.0 MPa.

4. The method according to claim 1, wherein the hydrochloric acid/ilmenite mass ratio in the step (1) is 0.8-12:1; and/or the reaction temperature T1 in the step (1) is 40-90° C. and/or the reaction time in the step (1) is 2-12 h.

5. The method according to claim 1, wherein the purity of the obtained titanium oxydichloride solution I is higher than 99.7 wt % and/or the purity of the obtained ferric trichloride solution II or III is higher than 99.6 wt %.

6. The method according to claim 1, wherein the content of foreign metal or variegated metal in the obtained titanium oxydichloride solution I is lower than 10 ppm; and/or the content of foreign metal in the obtained ferric trichloride solution II or III is lower than 20 ppm.

7. The method according to claim 1, wherein the co-extractant is selected from one or more of: secondary carbon primary amine, dimethylbenzene, tributyl phosphate, di(1-methylheptyl)methyl phosphonate, trioctylphosphine oxide, trialkyl phosphine oxide, bis(2-ethylhexyl) phosphate, mono(2-ethylhexyl) phosphate, 2-ethylhexyl phosphonic acid mono(2-ethylhexyl)ester, bis(2,4,4-trimethylpentyl) phosphinic acid, methyl isobutyl ketone, sec-octyl alcohol, methylbenzene, isopentanol or sulfonated kerosene.

8. The method according to claim 1, wherein the co-extractant is selected from secondary carbon primary amine/dimethylbenzene, tributyl phosphate/dimethylbenzene and a mixture of di(1-methylheptyl)methyl phosphonate, trioctyl phosphine oxide, trialkyl phosphine oxide, bis(2-ethylhexyl) phosphate, mono(2-ethylhexyl) phosphate, 2-ethylhexyl phosphonic acid mono(2-ethylhexyl)ester or bis(2,4,4-trimethylpentyl) phosphinic acid and dimethylbenzene, methyl isobutyl ketone, sec-octyl alcohol, methylbenzene, isopentanol or sulfonated kerosene.

9. The method according to claim 1, wherein the step (5) comprises one or more of the following steps: (5) sheet substrate coating step, the coating step comprises the following substeps: substep 5.1) coating of a Fe.sub.2O.sub.3 film layer: coating the sheet substrate raw materials with the Fe.sub.2O.sub.3 film layer by using the solution II and/or III to obtain iron based pearlescent pigments “substrate+Fe.sub.2O.sub.3” having a Fe.sub.2O.sub.3 coating layer, namely pearlescent pigments (PP5a), and optional substep 5.2) coating of a TiO.sub.2 film layer: further coating the prepared pearlescent pigments (PP5a) serving as the secondary sheet substrates with the TiO.sub.2 film layer by using the titanium oxydichloride solution I in the step (3) to obtain titanium-iron based pearlescent pigments “substrate+Fe.sub.2O.sub.3+TiO.sub.2” having a Fe.sub.2O.sub.3 coating layer and a TiO.sub.2 coating layer, namely pearlescent pigments (PP5ab); (6) sheet substrate coating step, the coating step comprises the following substeps: substep 6.1) coating of a TiO.sub.2 film layer: coating the sheet substrate raw material with the TiO.sub.2 film layer by using the titanium oxydichloride solution I in the step (3) to obtain titanium based pearlescent pigments “substrate+TiO.sub.2” having a TiO.sub.2 coating layer, namely pearlescent pigments (PP6a), and optional substep 6.2) coating of a Fe.sub.2O.sub.3 film layer: further coating the prepared pearlescent pigments (PP6a) serving as the secondary sheet substrates with the Fe.sub.2O.sub.3 film layer by using the solution II and/or III to obtain titanium-iron based pearlescent pigments “substrate+TiO.sub.2+Fe.sub.2O.sub.3” having a Fe.sub.2O.sub.3 coating layer and a TiO.sub.2 coating layer, namely pearlescent pigments (PP6ab); (7) sheet substrate coating step, the coating step comprises the following substeps: substep 7.1) coating of a TiO.sub.2/Fe.sub.2O.sub.3 film layer: coating the sheet substrate raw materials with the TiO.sub.2/Fe.sub.2O.sub.3 film layer by using a mixture formed by the solution II and/or III and the titanium oxydichloride solution I in the step (3) to obtain a titanium/iron based pearlescent pigments “substrate+TiO.sub.2/Fe.sub.2O.sub.3” having a TiO.sub.2/Fe.sub.2O.sub.3 coating layer, namely pearlescent pigments (PP7a), and the following two optional substeps 7.2) and 7.3): substep 7.2) coating of a SiO.sub.2 film layer: further coating the prepared pearlescent pigments (PP7a) serving as the secondary sheet substrates with the SiO.sub.2 film layer by using an aqueous sodium metasilicate solution to obtain pearlescent pigments “substrate+TiO.sub.2/Fe.sub.2O.sub.3+SiO.sub.2”, namely pearlescent pigments (PP7ab), and substep 7.3) coating of a TiO.sub.2/Fe.sub.2O.sub.3 film layer: coating the prepared pearlescent pigments (PP7ab) serving as the secondary sheet substrates with the TiO.sub.2/Fe.sub.2O.sub.3 film layer by using a mixture formed by the solution II and/or III and the titanium oxydichloride solution I in the step (3) to obtain pearlescent pigments “substrate+TiO.sub.2/Fe.sub.2O.sub.3+SiO.sub.2+TiO.sub.2/Fe.sub.2O.sub.3” having three coating layers, namely pearlescent pigments (PP7abc); (8) sheet substrate coating step, the coating step comprises the following substeps: substep 8.1) coating of a Fe.sub.2O.sub.3 film layer: coating the Fe.sub.2O.sub.3 film layer on sheet substrate raw materials by using the solution II and/or III to obtain iron based pearlescent pigments “substrate+Fe.sub.2O.sub.3”with a Fe.sub.2O.sub.3 coating layer, namely pearlescent pigment (PP8a), substep 8.2) coating a SiO.sub.2 film layer: further coating the SiO.sub.2 film layer on the prepared pearlescent pigments (PP8a) serving as the secondary sheet substrates by using an aqueous sodium metasilicate solution to obtain pearlescent pigment “substrate+Fe.sub.2O.sub.3+SiO.sub.2”, namely pearlescent pigments (PP8ab), and substep 8.3) coating of a Fe.sub.2O.sub.3 film layer: coating the Fe.sub.2O.sub.3 film layer on the prepared pearlescent pigments (PP8ab) serving as the secondary sheet substrates by using the solution II and/or III to obtain pearlescent pigments “substrate+Fe.sub.2O.sub.3+SiO.sub.2+Fe.sub.2O.sub.3”with three coating layers, namely pearlescent pigments (PP8abc); (9) sheet substrate coating step, the coating step comprises the following substeps: substep 9.1) coating of a TiO.sub.2 film layer: coating the sheet substrate raw materials with the TiO.sub.2 film layer by using the titanium oxydichloride solution I in the step (3) to obtain titanium based pearlescent pigments “substrate+TiO.sub.2” having TiO.sub.2 coating layer, namely pearlescent pigment (PP9a), substep 9.2) coating of a SiO.sub.2 film layer: further coating the prepared pearlescent pigments (PP9a) serving as the secondary sheet substrates with the SiO.sub.2 film layer by using an aqueous sodium metasilicate solution to obtain pearlescent pigments “substrate+TiO.sub.2+SiO.sub.2”, namely pearlescent pigments (PP9ab), and substep 9.3) coating of a TiO.sub.2 film layer: coating the prepared pearlescent pigments (PP9ab) serving as the secondary sheet substrates with the TiO.sub.2 film layer by using the titanium oxydichloride solution I in the step (3) to obtain pearlescent pigments “substrate+TiO.sub.2+SiO.sub.2+TiO.sub.2” having three coating layers, namely pearlescent pigments (PP9abc); or substep 9.3) coating of a Fe.sub.2O.sub.3 film layer: coating the prepared pearlescent pigments (PP9ab) serving as the secondary sheet substrates with the Fe.sub.2O.sub.3 film layer by using the solution II and/or III to obtain pearlescent pigments “substrate+TiO.sub.2+SiO.sub.2+Fe.sub.2O.sub.3” having three coating layers, namely pearlescent pigments (PP9abd); and/or (10) sheet substrate coating step, the coating step comprises the following substeps: substep 10.1) coating of a SnO.sub.2 film layer: coating the sheet substrate raw materials with the SnO.sub.2 film layer by using an aqueous stannic chloride solution to obtain tin based pearlescent pigments “substrate+SnO.sub.2” having a SnO.sub.2 coating layer, namely pearlescent pigments (PP10a); substep 10.2) coating of a TiO.sub.2 film layer: coating the prepared pearlescent pigment (PP10a) serving as the secondary sheet substrates with the TiO.sub.2 film layer by using the titanium oxydichloride solution I in the step (3) to obtain tin-titanium based pearlescent pigments “substrate+SnO.sub.2+TiO.sub.2” having a SnO.sub.2 coating layer and a TiO.sub.2 coating layer, namely pearlescent pigments (PP10ab), and optionally the following two substeps 10.3) and 10.4): substep 10.3) coating of a SiO.sub.2 film layer: further coating the prepared pearlescent pigments (PP10ab) serving as the secondary sheet substrates with the SiO.sub.2 film layer by using an aqueous sodium metasilicate solution to obtain pearlescent pigments “substrate+SnO.sub.2+TiO.sub.2+SiO.sub.2”, namely pearlescent pigments (PP10abc), and substep 10.4) coating of a TiO.sub.2 film layer: coating the prepared pearlescent pigments (PP10abc) serving as the secondary sheet substrates with the TiO.sub.2 film layer by using the titanium oxydichloride solution I in the step (3) to obtain pearlescent pigments “substrate+SnO.sub.2+TiO.sub.2+SiO.sub.2+TiO.sub.2” having four coating layers, namely pearlescent pigments (PP10abcd), or substep 10.4) coating of a SnO.sub.2 film layer and a TiO.sub.2 film layer: 10.4.1) firstly, coating the prepared pearlescent pigments (PP 10abc) serving as the secondary sheet substrates with the SnO.sub.2 film layer by using an aqueous stannic chloride solution to obtain pearlescent pigments “substrate+SnO.sub.2+TiO.sub.2+SiO.sub.2+SnO.sub.2” having a SnO.sub.2 coating layer, namely pearlescent pigments (PP10abce), 10.4.2) and then, coating the pearlescent pigments (PP10abce) as the secondary sheet substrates prepared in 10.4.1) with the TiO.sub.2 film layer by using the titanium oxydichloride solution I in the step (3) to obtain pearlescent pigments “substrate+SnO.sub.2+TiO.sub.2+SiO.sub.2+SnO.sub.2+TiO.sub.2” having five coating layers, namely pearlescent pigments (PP10abcef).

10. The method according to claim 9, wherein the substep 5.1) is performed as follows: adding water into the sheet substrates for beating and stirring to obtain a slurry having an initial solid content ranging from 3 wt % to 25 wt %, raising the temperature to an elevated temperature T3, adjusting the pH value of the slurry to be within the range of 1-5, adding the ferric trichloride solution II and/or III into the slurry at a certain feed rate, meanwhile, adding an alkali solution to keep the pH value constant, and reacting for a period of time to obtain sheet substrate/Fe.sub.2O.sub.3 pearlescent pigments; and/or the substep 6.1) is performed as follows: adding water into the sheet substrates for beating and stirring to obtain a slurry having an initial solid content ranging from 3 wt % to 25 wt %, raising the temperature to an elevated temperature T2, adjusting the pH value of the slurry to be within the range of 1-4, adding the titanium oxydichloride solution I prepared in the step (3) into the slurry at a certain feed rate, meanwhile, adding an alkali solution to keep the pH value constant, and reacting for a period of time to obtain sheet substrate/TiO.sub.2 pearlescent pigments.

11. The method according to claim 1, characterized in that the mass ratio of the extractant to the hydrochloric acid solution A0 containing titanium-iron ions in the step (2) is 1-6:1.

12. The method according to claim 1, characterized in that the titanium back extractant in the step (3) is selected from one or two of deionized water or dilute acid.

13. The method according to claim 1, characterized in that the mass ratio of the titanium back extractant to the titanium-iron enriched extract liquid A1 in the step (3) is 3-12:1.

14. The method according to claim 1, the sheet substrate raw materials in the step (5) are selected from natural mica, synthetic mica, glass sheets, flaky alumina, flaky silica, and various kinds of flaky metal.

15. Pearlescent pigments obtained by using the method of any one of claims 1-14 or 17-18, characterized in that the layered structure of the pigment comprises: substrate+TiO.sub.2 substrate+SnO.sub.2+TiO.sub.2. substrate+SnO.sub.2+TiO.sub.2+SiO.sub.2+TiO.sub.2 substrate+SnO.sub.2+TiO.sub.2+SiO.sub.2+SnO.sub.2+TiO.sub.2 substrate+TiO.sub.2+Fe.sub.2O.sub.3 substrate+TiO.sub.2+SiO.sub.2+Fe.sub.2O.sub.3 substrate+TiO.sub.2/Fe.sub.2O.sub.3 substrate+TiO.sub.2/Fe.sub.2O.sub.3+SiO.sub.2+TiO.sub.2/Fe.sub.2O.sub.3 substrate+Fe.sub.2O.sub.3 substrate+Fe.sub.2O.sub.3+TiO.sub.2 substrate+Fe.sub.2O.sub.3+SiO.sub.2+Fe.sub.2O.sub.3; or substrate+TiO.sub.2+SiO.sub.2+TiO.sub.2.

16. Use of the pearlescent pigment of claim 15 in the fields of paints, printing ink, plastics, ceramic materials, leather coloring, wallpaper, paint spraying, powder coatings or cosmetics.

17. The method according to claim 1, wherein the ilmenite in step (1) is titanium concentrates, high titanium slags, or modified titanium concentrates containing 30-80 wt % of titanium dioxide.

18. The method according to claim 1, wherein the titanium back extractant in step (3) is dilute hydrochloric acid having a concentration of 0.5-10 wt %.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0097] FIG. 1 is a production flow chart of a process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0098] Detailed description is further given below to the present invention, in combination with the embodiments, for further understanding of the present invention, but is not intended to limit the present invention. It should be understood that these descriptions are made only for further describing the features and advantages of the present invention but not for the purpose of limiting the claims of the present invention. Any equivalent substitution in this field made according to the contents of the present invention should fall within the scope of protection of the present invention.

EXAMPLE 1

[0099] (1) 1500 g of 37% concentrated hydrochloric acid is added to 500 g of high titanium slag (with a titanium dioxide content of 38.7 wt %) and stirred, temperature is raised to 60° C., and hydrogen chloride gas is introduced to maintain the pressure of the reaction kettle at 1 MPa. After reaction of 9 h, press filtration is performed, the filter residues are washed to be neutral, the filtrate is cooled, and then centrifugalized to obtain a titanium-iron solution and a ferrous chloride precipitate. The acidolysis rate of the high titanium slag is up to 98%, the titanium recovery rate is up to 96%, and the iron recovery rate is up to 99%. (2) At 30° C., using the secondary carbon primary amine N1923/dimethylbenzene (wt)=1:1 as an extractant and the ratio of the oil phase to the water phase O/A of 2:1, primary extraction is conducted, and the oil phase is an iron-titanium extract phase (the sum of Mn, V and Cr contents is lower than 2 ppm) and the water phase is an impurity-containing raffinate phase. (3) At 30° C., the iron-titanium extract phase is back extracted with 10% of dilute hydrochloric acid at the O/A ratio of 1:1, the oil phase extractant is introduced into a Fe back extractor, 190 g/L of pure titanium oxydichloride solution I (the purity is higher than 99.99 wt %, and the sum of Mn, V and Cr contents is lower than 2 ppm) that can be used for coating pearlescent pigments is obtained from the water phase, as shown in Table 1. Iron is back extracted with water from the organic phase A2 containing iron ions in the Fe back extractor to obtain a pure ferric trichloride solution II (the purity is higher than 99.99 wt %, and the foreign metal content is lower than 6 ppm) which can be used as a coating material of mica iron pearlescent pigments; the organic phase (oil phase) is returned to the co-extractor; the oxidized ferrous chloride precipitate C1 is dissolved in water to prepare a ferric trichloride solution III (the purity is higher than 99.99 wt %, and the foreign metal content is lower than 6 ppm) which can be used as a coating material of the mica iron pearlescent pigments; or the ferrous chloride precipitate C1 is directly calcined to obtain iron oxide red pigments; or the ferric trichloride solution II is used to obtain the iron oxide red pigments by means of alkali precipitation or through a hydrothermal method.

[0100] The impurity-containing raffinate phase obtained in the step (2) is delivered to a hydrochloric acid and hydrogen chloride gas recovery process, and variegated ions are conveniently recovered in the hydrochloric acid and hydrogen chloride gas recovery process.

TABLE-US-00001 TABLE 1 Composition of high titanium slag and acidolysis solution extract liquid TiO.sub.2 ΣFe FeO MgO MnO SiO.sub.2 Al.sub.2O.sub.3 CaO Before acidolysis 49.6 15.2 10.88 1.05 2.07 1.11 2.24 1.34 (%) After acidolysis 192 24.96 68*   0.103 0.11 0.038 0.174 0.091 (g/L) Raffinate (ppm) 3916 67 — 183 209 4 175 10 Primary 191.6 0.0004 — 0.0009 0.0007 0 0.0011 0.0003 back-extraction liquid (g/L) Note: *the ferrous chloride precipitate is calculated based on the oxide

COMPARATIVE EXAMPLE 1

[0101] (1) 1500 g of 37% concentrated hydrochloric acid is added to 500 g of high titanium slag (with a titanium dioxide content of 38.7 wt %) and stirred, temperature is raised 70° C. to perform reaction for 7 hours, 50 g of KClO.sub.3 is added thereto, and the reaction is continued for 1 h and then stopped, after cooling to room temperature, press filtration is performed, filter residues are washed to be neutral. (2) At 30° C., using the TBP/dimethylbenzene (wt)=1:2 as the extractant and the ratio of the oil phase to the water phase O/A of 3:1, 4-stage extractions are conducted, and the oil phase is an iron extraction phase and the water phase is a titanium raffinate phase. (3) The iron extraction phase is back extracted with deionized water at the ratio of O/A=1:10, the oil phase extractant is returned to the Fe back extractor, the water-phase iron is then extracted/back-extracted for purification, a part of water is removed by distillation for concentration, so that the iron content is up to 160 g/L, thereby obtaining a ferric trichloride solution. The titanium raffinate phase is introduced into an impurity-removing extractor, multistage counter-current extractions V are performed by using the extractant, TBP/dimethylbenzene=4:25 at a ratio of O/A=2:1, and the raffinate is introduced into the impurity removing extractor 2, and is extracted on Mn with TBP/dimethylbenzene=1:9 at a ratio of O/A=2:1; the extract liquid is back extracted to obtain a raffinate, i.e., titanium-rich TiOCl.sub.2, in which the Ti content may be up to 100000 ppm, thereby preparing a titanium oxydichloride solution which can be used for coating the pearlescent pigments, with the sum of Mn, V and Cr content being 15 ppm.

EXAMPLE 2

[0102] The technological conditions are same as those in Example 1, but the high titanium slag is replaced with the ilmenite concentrate.

EXAMPLE 3

[0103] The technological conditions are same as those in Example 1, but the high titanium slag is replaced with the modified ilmenite concentrate. In addition, in the step (2), at 30° C., using the secondary carbon primary amine N1923/dimethylbenzene (wt)=1:1 as an extractant and the ratio of the oil phase to the water phase O/A of 2:1, two-stage extractions are conducted, and the resulting combined oil phase is an iron-titanium extraction phase (the sum of the Mn, V and Cr contents is lower than 2.5 ppm) and the water phase is an impurity-containing raffinate phase.

EXAMPLE 4

[0104] 100 g of mica having a particle size of 10-60 μm and a diameter-to-thickness ratio of more than 50 is weighed and placed into a 2 L beaker, 1500 mL of deionized water is added thereto, the beaker is placed into a water bath kettle, stirring is performed at a rate of 200-300 rps, temperature is raised to 75-85° C., and the pH value of the solution is adjusted to 3-4, the aqueous ferric trichloride solution in Example 1 is added dropwise into the beaker at a rate of 2 mL/min, and the pH value of the solution is maintained constant by using a 30% of NaOH solution. After reaction for 5-6 h, the solution is filtered, the filter cake is oven-dried and then placed into a muffle furnace to be heated to 900° C. at a heating rate of 10° C./min and maintained for 1 h, and is taken out and cooled to the room temperature, thereby obtaining red mica iron pearlescent pigments.

EXAMPLE 5

[0105] 100 g of mica having a particle size of 10-60 μm and a diameter-to-thickness ratio of more than 50 is weighed and placed into a 2 L beaker, 1500 mL of deionized water is added thereto, the beaker is placed into a water bath kettle, stirring is performed at a rate of 200-300 rps, temperature is raised to 75-85° C., the pH value of the solution is adjusted to 3-4, the aqueous ferric trichloride solution in Example 1 is added dropwise into the beaker at a rate of 2 mL/min, and the pH value of the solution is maintained constant by using a 30% of NaOH solution. After reaction for 5-6 h, the pH value is increased to 8.0 by using the 30% of NaOH solution, 20% of aqueous sodium metasilicate solution is added dropwise at a rate of 1.0 ml/min, after reaction for 1 h, the pH value of the solution is adjusted to 3-4 by using 1:1 hydrochloric acid, the solution is added dropwise into the beaker at a rate of 2 mL/min, and the pH value of the solution is maintained constant by using the 30% of NaOH solution. After reaction for 5-6 h, the solution is filtered, the filter cake is oven-dried and then placed into a muffle furnace to be heated to 900° C. at a heating rate of 10° C./min and maintained for 1 h, and is taken out and cooled to the room temperature, thereby obtaining red mica iron pearlescent pigments.

EXAMPLE 6

[0106] 100 g of mica having a particle size of 10-60 μm and a diameter-to-thickness ratio of more than or equal to 60 is weighed and placed into a 5 L beaker, 2000 mL of deionized water is added thereto, the beaker is placed into a water bath kettle, stirring is performed at a rate of 200-300 rps, temperature is raised to 60-70° C., the pH value of the solution is adjusted to 1.2-1.8, 100 mL of 2.5% aqueous stannic chloride solution is added, the pH value of the solution is maintained constant by using 30% of NaOH solution, the addition is finished within half an hour, then, temperature is raised to 75-85° C., the pH value is adjusted to 1.5-2.5, the titanium oxychloride solution in Example 1 is added into the beaker at a rate of 1 mL/min, and the pH value of the solution is maintained constant by using the NaOH solution. After reaction for 6-7 h, the solution is filtered, the filter cake is oven-dried and then placed into a muffle furnace to be heated to 800° C. at a heating rate of 10° C./min and maintained for 1 h, and is taken out and cooled to the room temperature, thereby obtaining golden rainbow mica titanium pearlescent pigments.

EXAMPLE 7

[0107] 100 g of mica having particle size of 10-60 μm and a diameter-to-thickness ratio of more than or equal to 60 is weighed and placed into a 5 L beaker, 2000 mL of deionized water is added thereto, the beaker is placed into a water bath kettle, and stirring is performed at a rate of 200-300 rps, temperature is raised to 60-70° C., the pH value of the solution is adjusted to 1.2-1.8, 100 mL of 2.5% aqueous stannic chloride solution is added, the pH value of the solution is maintained constant by using 30% of NaOH solution, the addition is finished within half an hour, then, temperature is raised to 75-85° C., the pH value is adjusted to 1.5-2.5, the titanium oxychloride solution in Example 1 is added dropwise into the beaker at a rate of 1 mL/min, and the pH value of the solution is maintained constant by using the NaOH solution. After reaction for 6-7 h, the pH value is increased to 8.0 by using the 30% of NaOH solution, 20% of aqueous sodium metasilicate solution is added dropwise at a rate of 1.0 ml/min, after reaction for 1 h, the pH value of the solution is adjusted to 1.5-2.5 by using 1:1 hydrochloric acid, the solution is added dropwise into the beaker at a rate of 1 mL/min, and the pH value of the solution is maintained constant by using the NaOH solution, after reaction for 6-7 h, the solution is filtered, the filter cake is oven-dried and then placed into a muffle furnace to be heated to 800° C. at a heating rate of 10° C./min and maintained for 1 h, and is taken out and cooled to the room temperature, thereby obtaining golden rainbow mica titanium pearlescent pigments.

EXAMPLE 8

[0108] 100 g of mica having particle size of 10-60 μm and a diameter-to-thickness ratio of more than or equal to 60 is weighed and placed into a 5 L beaker, 2000 mL of deionized water is added thereto, the beaker is placed into a water bath kettle, and stirring is performed at a rate of 200-300 rps, temperature is raised to 60-70° C., the pH value of the solution is adjusted to 1.2-1.8, 100 mL of 2.5% aqueous stannic chloride solution is added, the pH value of the solution is maintained constant by using 30% of NaOH solution, the addition is finished within half an hour, then, temperature is raised to 75-85° C., the pH value of the solution is adjusted to 1.5-2.5, the titanium oxychloride solution in Example 1 is added dropwise into the beaker at a rate of 1 mL/min, and the pH value of the solution is maintained constant by using the NaOH solution, after reaction for 6-7 h, the pH value of the solution is adjusted to 3-4 by using the 30% of NaOH solution, the solution is added dropwise into the beaker at a rate of 2 mL/min, and the pH value of the solution is maintained constant by using the 30% of NaOH solution, after reaction for 5-6 h, the solution is filtered, and the filter cake is oven-dried and then placed into a muffle furnace to be heated to 900° C. at a heating rate of 10° C./min and maintained for 1 h, and is taken out and cooled to the room temperature, thereby obtaining golden pearlescent pigments.

TABLE-US-00002 TABLE 2 Performance indexes of the pearlescent pigments Oil absorption Bulk Serial Particle size Density volume density PH value number (D50 μm) (g/cm.sup.3) (g/100 g) (g/cm.sup.3) of 10% Wt KC205 22.5 3.1 60.5 0.25 7.76 Example 8 22.2 3.2 60.7 0.26 7.78 Example 4 22.4 3.2 61.9 0.28 7.67 KC500 22.3 3.2 62.7 0.27 7.60

TABLE-US-00003 TABLE 3 Optical properties of the pearlescent pigments L* a* b* C* h° Example 4 15° 91.61 33.80 56.10 65.50 58.93 25° 71.94 30.31 47.06 55.98 57.22 45° 43.03 24.62 32.93 41.12 53.22 75° 26.39 22.33 26.09 34.34 49.45 110°  20.59 22.53 24.32 33.15 47.19 KC500 15° 92.23 33.15 55.89 64.98 59.33 25° 72.53 29.99 46.92 55.69 57.41 45° 43.96 24.34 32.85 40.88 53.46 75° 25.91 22.01 25.72 33.85 49.44 110°  19.99 22.28 23.83 32.62 46.92 Example 6 15° 110.86 0.64 47.01 47.01 89.22 25° 93.86 −0.35 31.65 31.65 90.63 45° 70.13 −0.79 7.15 7.19 96.27 75° 59.85 −0.90 −4.98 5.06 259.76 110°  58.66 −1.11 −4.63 4.76 256.52 KC205 15° 110.55 0.01 46.39 46.39 89.99 25° 94.26 −0.65 31.73 31.74 91.17 45° 70.67 −1.10 7.76 7.84 98.07 75° 60.14 −1.10 −4.38 4.52 255.90 110°  58.89 −1.30 −4.09 4.29 252.41

[0109] From table 3, it can be seen clearly that the products in examples 4 and 6 of the present invention have grotesque angle-dependent optical effects and strong colorful effects.

APPLICATION EXAMPLES

[0110] The pearlescent pigments prepared in examples 4-9 above are used in the application fields of paints, coatings, printing ink, plastics, ceramic materials, leather coloring, wallpaper, powder coatings and cosmetics. For example, by adding the pearlescent pigment of the present invention to paints or coatings, a coating layer with extremely excellent color and luster can be prepared.

Application Example 1

Application to Paint Spraying

[0111] 4.00 g of pearlescent pigment is accurately weighed, and added to a stirrer along with 4.0 g of butyl acetate and 8.0 g of polyester automobile coating resin for stirring and dispersion for 10 min, and 84.0 g of automobile coating resin systems are further added and stirred for 5 min. Firstly, the viscosity of the coating is adjusted to a Ford cup 4 for 14-15 s before spraying; the temperature of a spraying room is controlled at 25° C. and the relative humidity is controlled at 60% during spraying; and spraying is performed twice, a varnish is applied after air drying for 10 min, and is baked at 140° C. for 30 min after performing flash drying again.

Application Example 2

Application to Injection Molding

[0112] 200 g of polypropylene (PP) dried at 105° C. is accurately weighed and placed into a sealable plastic bag, 1 mL of varnish (also called dispersed oil) is added and then shaken to mix the varnish with a polypropylene material well.

[0113] 4.000 g of pearl powder is weighed by using an analytical balance, and added into the sealable plastic bag, the resulting mixture was shaken again, and kneaded to sufficiently and uniformly disperse the pearl powders into PP particles.

[0114] After the barrel temperature of an extruder reaches a set value (generally 180-200° C.), the prepared polypropylene material is added into its hopper, and the original residual material in the hopper is squeezed out by virtue of rubber injection and rubber melting functions until the new material is squeezed out, wherein the new squeezed material should be glossy and free from impurities, black spots, scorches or air bubbles; and meanwhile, the nozzle should be avoided from blocking during rubber injection. After two plastic sheets to be discharged successively have no difference, the plastic sheets produced thereafter are stable and qualified products, and continuous automatic production may be initiated.