A method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption

Abstract

A method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption comprises vapor-coating the titanium dioxide with a first layer of alumina, followed by dispersion treatment. The dispersed titanium dioxide slurry is then wet-coated. First, a second, loose alumina film is coated on the titanium dioxide surface with a basic aluminum salt. Then, a third, loose silica film is coated on the titanium dioxide surface with a silicate solution. Finally, a fourth, loose alumina film is coated on the titanium dioxide surface with a basic aluminum salt. The wet-coated slurry is aged for 0.5 hours and then washed, filtered, dried, and vapor-coated to obtain titanium dioxide powder for cosmetics with high hiding power and high oil absorption. Advantages of this method include a simple process, strict control of the amount of coating applied to the titanium dioxide powder, high hiding power and high oil absorption, and maintained UV resistance.

Description

Technical Field

[0001] The invention relates to a method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption. Background Art

[0002] Titanium dioxide is widely used in cosmetics due to its excellent chemical and thermal stability, as well as its non-toxicity and odorlessness. With the increasing differentiation of functional cosmetics, the demand for titanium dioxide in concealing and oil-absorbing cosmetics is increasing.

[0003] Submicron titanium dioxide itself has certain hiding power and oil absorption. In order to further improve the hiding power of titanium dioxide, inorganic film is often used to coat the surface of titanium dioxide, but there are few reports on improving the oil absorption performance of titanium dioxide.

[0004] CN111849211A discloses a "method for preparing a titanium dioxide pigment with high light resistance and high hiding power for papermaking." This method improves the hiding power of titanium dioxide by coating a mixed film of titanium phosphate and cerium phosphate with a layer of Fe2O3. However, the Fe2O3 used is reddish-brown, and the cerium is yellowish, which reduces the whiteness of the titanium dioxide after coating. CN106497147A discloses a "method for preparing a titanium dioxide pigment with high hiding power, high weather resistance, and high whiteness." This method uses a loose silicon film coating, which improves the hiding power to a certain extent. This method improves the hiding power through a large amount of coating, but the coating amount is large and the production cost is high. The large coating amount directly increases the coating layer thickness, which in turn increases the titanium dioxide particle size and reduces the UV resistance, which affects the use of titanium dioxide in cosmetics. In addition, neither coating method significantly improves the oil absorption of titanium dioxide. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption. The process is simple, and the coating amount of the titanium dioxide powder is strictly controlled while the powder has high hiding power and high oil absorption properties and maintains the anti-ultraviolet ability of titanium dioxide.

[0006] The technical solution of the present invention is:

[0007] A method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption, the specific steps of which are as follows:

[0008] 1) Titanium dioxide first layer of alumina vapor coating

[0009] Titanium dioxide is prepared by a vapor-phase oxidation process using refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the flow rate of refined titanium tetrachloride introduced into an oxidation reaction generator is controlled to be 5500 kg / h to 6500 kg / h and the pressure is controlled to be 0.5 MPa to 0.8 MPa; the flow rate of oxygen is simultaneously controlled to be 1212 kg / h to 1403 kg / h and the oxygen pressure is controlled to be 1.2 MPa to 1.4 MPa; the hot oxygen is preheated to 1700 to 1800° C. in an oxidation reactor using heat generated by toluene combustion, so that the titanium tetrachloride and oxygen undergo a vapor-phase oxidation reaction, and aluminum trichloride, potassium chloride and deionized water are simultaneously added, wherein the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride and deionized water are 1000:10, 1000:1 and 1000:6, respectively.

[0010] In the cooling section after the vapor-phase oxidation reaction of refined titanium tetrachloride in the oxidation reaction generator, where the temperature of titanium dioxide produced by vapor-phase oxidation of titanium tetrachloride is between 1500°C and 1600°C, preheated vapor-phase aluminum trichloride is added at a flow rate of 25kg / h to 50kg / h and a pressure of 1.0MPa to 1.2MPa to vapor-coat the titanium dioxide with aluminum oxide;

[0011] 2) Titanium dioxide dispersion treatment

[0012] The titanium dioxide vapor-coated with alumina is added to distilled water for slurrying, and the pH value is controlled at 10.0-10.5 with an inorganic alkali solution. After aging for 20 minutes, a sodium hexametaphosphate solution is added for dispersion treatment for 0.5 hours, followed by sand grinding and stirring to obtain a titanium dioxide dispersion slurry. The titanium dioxide dispersion slurry is heated to 50° C.-60° C. and maintained at this temperature throughout the coating process.

[0013] 3) Wet coating of titanium dioxide: The titanium dioxide dispersion slurry of step 2) is wet coated. First, a second loose aluminum oxide film is coated on the surface of the titanium dioxide with a basic aluminum salt, wherein the amount of the basic aluminum salt solution added is 0.8% to 1.2% by weight of Al2O3 in the basic aluminum salt relative to the weight of TiO2. Then, a third loose silicon oxide film is coated on the surface of the titanium dioxide with a silicate solution, wherein the amount of the silicate added is 2% to 4% by weight of SiO2 in the silicate relative to the weight of TiO2. Finally, a fourth loose aluminum oxide film is coated on the surface of the titanium dioxide with a basic aluminum salt, wherein the amount of the basic aluminum salt solution added is 0.6% to 1.0% by weight of Al2O3 in the basic aluminum salt relative to the weight of TiO2.

[0014] 4) Titanium dioxide post-treatment

[0015] The wet-coated slurry was aged for 0.5 h, and then washed, filtered, dried, and air-powdered to obtain titanium dioxide powder for cosmetics with high hiding power and high oil absorption.

[0016] Furthermore, in step 1), the pressure of the preheated gaseous aluminum chloride is 300 kPa to 900 kPa, and the temperature is 730° C. to 880° C.

[0017] Furthermore, in step 3), the basic aluminum salt is selected from at least one of sodium metaaluminate and potassium metaaluminate, and the concentration of the basic aluminum salt is 170 g / L to 200 g / L in terms of Al2O3.

[0018] Furthermore, when coating the second layer of loose alumina and the fourth layer of loose alumina, the titanium dioxide dispersion treatment slurry is controlled to have a pH value of 7.5-8.5 with an inorganic acid solution and an inorganic base solution, respectively, and matured for 20 minutes; basic aluminum salt is added within 0.5h-1.0h, and the pH value is controlled to 7.5-8.5 with an acidic aluminum salt, and matured for 0.5h to obtain a loose alumina film.

[0019] Furthermore, when coating the third layer of loose silicon oxide, the titanium dioxide slurry coated with the second layer of loose aluminum oxide film is controlled to have a pH value of 4.0 to 6.0 with an inorganic acid solution and matured for 20 minutes; a silicate solution is added within 1.0 to 1.5 hours, and the pH value is controlled to 4.0 to 6.0 with an inorganic acid solution at the same time, and matured for 0.5 to 1 hour to obtain a third layer of loose silicon oxide film.

[0020] Furthermore, in step 2), the amount of sodium hexametaphosphate solution added is 0.2% to 0.3% by weight based on the weight of P2O5 to TiO2, and the concentration of the sodium hexametaphosphate solution is 210 g / L to 220 g / L based on P2O5.

[0021] As a further preference, the acidic aluminum salt is selected from at least one of aluminum sulfate and aluminum chloride, and the concentration of the acidic aluminum salt is 90 g / L to 110 g / L in terms of Al2O3.

[0022] Furthermore, in step 3), the silicate is selected from at least one of sodium silicate and potassium silicate; the mass ratio of the silicate to titanium dioxide is 2% to 4% by weight of SiO2 to TiO2; and the concentration of the silicate is 200g / L to 220g / L based on SiO2.

[0023] Further preferably, the inorganic alkali solution is one of sodium hydroxide or potassium hydroxide; the mass concentration of the inorganic alkali solution is 10% to 20%.

[0024] Furthermore, during the beating treatment, the mass concentration of the titanium dioxide slurry obtained is 20% to 30%.

[0025] As a further preference, the inorganic acid solution is one of hydrochloric acid or sulfuric acid, and the mass concentration of the inorganic acid solution is 10% to 20%.

[0026] Beneficial effects of the present invention:

[0027] (1) The first layer of titanium dioxide is coated by vapor coating. Compared with the traditional wet coating, the coating layer is continuous, dense and uniform, which improves the weather resistance of titanium dioxide. The aluminum oxide coating exists in the form of a pure oxide and does not have surface hydroxyl groups. The coating layer is thin, which effectively controls the particle size of the coated titanium dioxide powder particles and ensures UV resistance.

[0028] (2) Under alkaline conditions, the second layer of loose aluminum film is wet-coated. Its thin rod-shaped boehmite structure has large porosity and good dispersibility, which inhibits the agglomeration of titanium dioxide particles and is conducive to the coating of the third layer of loose porous sponge-like silica, because the hydroxylated aluminum ions can prevent the aggregation of silica gel particles; the coating of the second layer of loose aluminum and the third layer of loose silica can effectively improve the product's covering power and oil absorption; and the fourth layer of loose aluminum coating can improve the thixotropy of the filter cake and increase the dispersibility of titanium dioxide in cosmetics.

[0029] In summary, the amount of silicon-aluminum coating is far less than the coating amount of a single loose silica film, which effectively reduces the production cost, ensures the UV resistance of titanium dioxide, and at the same time realizes the functional requirements of titanium dioxide for high hiding power and high oil absorption in cosmetic applications. DETAILED DESCRIPTION

[0030] Example 1

[0031] 1) Titanium dioxide first layer of alumina vapor coating

[0032] Titanium dioxide is produced by vapor-phase oxidation of refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the refined titanium tetrachloride flow rate in the oxidation reactor is controlled at 5500 kg / h and a pressure of 0.5 MPa; the oxygen flow rate is controlled at 1212 kg / h and an oxygen pressure of 1.2 MPa. The hot oxygen is preheated to 1700°C in the oxidation reactor using heat generated by toluene combustion, causing a vapor-phase oxidation reaction between the titanium tetrachloride and oxygen. Aluminum trichloride, potassium chloride, and deionized water are simultaneously added, with the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride, and deionized water being 1000:10, 1000:1, and 1000:6, respectively. The preheated vaporized aluminum trichloride is added to the cooling section after the vapor-phase oxidation reaction of the refined titanium tetrachloride in the oxidation reactor, where the temperature of the vapor-phase oxidation titanium tetrachloride product is 1500°C. The preheated vaporized aluminum trichloride has a pressure of 300 kPa and a temperature of 730°C. When adding gaseous aluminum chloride, the aluminum chloride flow rate is controlled at 25 kg / h and the pressure is controlled at 1.0 MPa. After the gaseous oxidation reaction is completed, the gas enters the bag filter through the cooler.

[0033] 2) Titanium dioxide dispersion treatment

[0034] The titanium dioxide vapor-coated with alumina was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 20%. The pH value was controlled to 10.0 with a 10% sodium hydroxide solution. After aging for 20 minutes, 210 g / L sodium hexametaphosphate (based on the weight of P2O5 in the sodium hexametaphosphate accounting for 0.2% of the weight of TiO2) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 50°C and the entire coating process was carried out at this temperature.

[0035] 3) Coating with a second layer of loose alumina

[0036] After aging for 0.5 h, adjust the pH to 7.5 with a 10% hydrochloric acid solution and age for 20 min. Add 170 g / L of sodium aluminate (based on Al2O3) to the slurry within 0.5 h, with the amount of sodium aluminate added being 0.8% of the weight of Al2O3 in the sodium aluminate relative to the TiO2. Simultaneously, control the pH to 7.5 with 90 g / L of aluminum sulfate (based on Al2O3). After the addition is complete, age for 0.5 h. 4) Coat with a third loose layer of silicon oxide.

[0037] Adjust the pH to 4.0 with a 10% hydrochloric acid solution and mature for 20 minutes; add a sodium silicate solution with a concentration of 170g / L in terms of SiO2 to the slurry within 1 hour, so that SiO2 accounts for 2% of the weight of TiO2 in the sodium silicate, and simultaneously control the pH to 4.0 with a 10% hydrochloric acid solution and mature for 0.5 hour;

[0038] 5) Coating the fourth layer of loose alumina

[0039] The pH value is controlled at 7.5 using sodium hydroxide with a mass concentration of 10%, and the mixture is aged for 20 minutes. Within 0.5 hour, sodium aluminate with a concentration of 170 g / L calculated as Al2O3 is added to the slurry, and the amount of sodium aluminate added is 0.6% by weight of Al2O3 to TiO2 in the sodium aluminate. At the same time, aluminum sulfate with a concentration of 90 g / L calculated as Al2O3 is used to control the pH value at 7.5, and the mixture is aged for 0.5 hour. After washing, filtering, drying, and degassing, titanium dioxide powder with high hiding power and high oil absorption for cosmetics is obtained.

[0040] Example 2

[0041] 1) Titanium dioxide first layer of alumina vapor coating

[0042] Titanium dioxide is produced by vapor-phase oxidation of refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the refined titanium tetrachloride flow rate in the oxidation reactor is controlled at 6500 kg / h and a pressure of 0.8 MPa; the oxygen flow rate is controlled at 1403 kg / h and an oxygen pressure of 1.4 MPa. The hot oxygen is preheated to 1800°C in the oxidation reactor using heat generated by toluene combustion, causing a vapor-phase oxidation reaction between the titanium tetrachloride and oxygen. Aluminum trichloride, potassium chloride, and deionized water are simultaneously added, with the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride, and deionized water being 1000:10, 1000:1, and 1000:6, respectively. The preheated vapor aluminum trichloride is added to the cooling section after the vapor-phase oxidation reaction of the refined titanium tetrachloride in the oxidation reactor, where the temperature of the vapor-phase oxidation titanium tetrachloride product is 1600°C. The preheated vapor aluminum trichloride has a pressure of 900 kPa and a temperature of 880°C. When adding gaseous aluminum chloride, the aluminum chloride flow rate is controlled at 50 kg / h and the pressure is controlled at 1.2 MPa. After the gaseous oxidation reaction is completed, the gas enters the bag filter through the cooler.

[0043] 2) Titanium dioxide dispersion treatment

[0044] The titanium dioxide vapor-coated with alumina was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 30%. The pH value was controlled at 10.5 with a 20% potassium hydroxide solution. After aging for 20 minutes, 220 g / L sodium hexametaphosphate (based on the weight of P2O5 in the sodium hexametaphosphate accounting for 0.3% of TiO2) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 60°C and the entire coating process was carried out at this temperature.

[0045] 3) Coating with a second layer of loose alumina

[0046] After aging for 0.5 h, adjust the pH to 8.5 with a 20% sulfuric acid solution and age for 20 min. Add 200 g / L of potassium aluminate (calculated as Al2O3) to the slurry within 1 h, in an amount such that Al2O3 accounts for 1.2% of the weight of TiO2 in the potassium aluminate. Simultaneously, control the pH to 8.5 with 110 g / L of aluminum chloride (calculated as Al2O3). After the addition is complete, age for 0.5 h.

[0047] 4) Coating the third layer of loose silicon oxide

[0048] The pH value was adjusted to 6.0 with a 20% sulfuric acid solution and the mixture was aged for 20 minutes. Within 1.5 hours, a potassium silicate solution having a concentration of 220 g / L in terms of SiO2 was added to the slurry, with the SiO2 content in the potassium silicate being 4% by weight of the TiO2 content. The pH value was simultaneously controlled to 6.0 with a 20% sulfuric acid solution and the mixture was aged for 0.5 hours.

[0049] 5) Coating the fourth layer of loose alumina

[0050] The pH value is controlled at 8.5 with potassium hydroxide having a mass concentration of 20%, and the mixture is aged for 20 minutes. Within 1 hour, potassium aluminate having a concentration of 200 g / L calculated as Al2O3 is added to the slurry, and the amount of potassium aluminate added is 1.0% by weight based on the weight of Al2O3 to TiO2 in the potassium aluminate. At the same time, aluminum chloride having a concentration of 110 g / L calculated as Al2O3 is used to control the pH value at 8.5, and the mixture is aged for 0.5 hour. After washing, filtering, drying, and powdering, titanium dioxide powder for cosmetics with high hiding power and high oil absorption is obtained.

[0051] Example 3

[0052] 1) Titanium dioxide first layer of alumina vapor coating

[0053] Titanium dioxide is produced by vapor-phase oxidation of refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the refined titanium tetrachloride flow rate in the oxidation reactor is controlled at 6000 kg / h and a pressure of 0.65 MPa; the oxygen flow rate is controlled at 1318 kg / h and an oxygen pressure of 1.3 MPa. The hot oxygen is preheated to 1750°C in the oxidation reactor using heat generated by toluene combustion, causing a vapor-phase oxidation reaction between the titanium tetrachloride and oxygen. Aluminum trichloride, potassium chloride, and deionized water are simultaneously added, with the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride, and deionized water being 1000:10, 1000:1, and 1000:6, respectively. The preheated vapor aluminum trichloride is added to the cooling section after the vapor-phase oxidation reaction of the refined titanium tetrachloride in the oxidation reactor, where the temperature of the vapor-phase oxidation titanium tetrachloride product is 1550°C. The preheated vapor aluminum trichloride has a pressure of 600 kPa and a temperature of 810°C. When adding gaseous aluminum chloride, the aluminum chloride flow rate is controlled at 38 kg / h and the pressure is controlled at 1.1 MPa. After the gaseous oxidation reaction is completed, the gas enters the bag filter through the cooler.

[0054] 2) Titanium dioxide dispersion treatment

[0055] The titanium dioxide vapor-coated with alumina was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 25%. The pH value was controlled at 10.3 with a 16% sodium hydroxide solution. After aging for 20 minutes, 216 g / L sodium hexametaphosphate (based on the weight of P2O5 in the sodium hexametaphosphate accounting for 0.25% of the weight of TiO2) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 56°C and the entire coating process was carried out at this temperature.

[0056] 3) Coating with a second layer of loose alumina

[0057] After aging for 0.5 h, the pH was adjusted to 8.2 with a 16% hydrochloric acid solution and aged for 20 min; within 0.8 h, sodium aluminate with a concentration of 188 g / L in terms of Al2O3 was added to the slurry, the amount of sodium aluminate added being 1.0% by weight of Al2O3 in the sodium aluminate relative to the TiO2, and aluminum sulfate with a concentration of 102 g / L in terms of Al2O3 was used to control the pH value to 8.2. After the addition was completed, the slurry was aged for 0.5 h; 4) the third layer of loose silicon oxide was coated with a 16% hydrochloric acid solution with a pH value of 5.2 and aged for 20 min; within 1.3 h, sodium silicate solution with a concentration of 212 g / L in terms of SiO2 was added to the slurry based on the SiO2 relative to the TiO2 relative to 3.2% by weight of the sodium silicate, and the pH value was controlled to 5.2 with a 16% hydrochloric acid solution and aged for 0.5 h;

[0058] 5) Coating the fourth layer of loose alumina

[0059] The pH value is controlled at 8.2 using sodium hydroxide having a mass concentration of 16%, and the mixture is aged for 20 minutes. Within 0.8 hours, sodium aluminate having a concentration of 188 g / L in terms of Al2O3 is added to the slurry, and the amount of sodium aluminate added is 0.8% by weight based on the weight of Al2O3 to TiO2 in the sodium aluminate. At the same time, aluminum sulfate having a concentration of 102 g / L in terms of Al2O3 is used to control the pH value at 8.2, and the mixture is aged for 0.5 hours. After washing, filtering, drying, and degassing, titanium dioxide powder for cosmetics with high hiding power and high oil absorption is obtained.

[0060] Comparative Example 1

[0061] In a comparative example, the method of coating the first aluminum film under acidic conditions instead of vapor phase oxidation in Example 3 was selected. The parameters of the oxidation reaction generator were controlled the same as in Example 3. The steps were as follows:

[0062] 1) Titanium dioxide dispersion treatment

[0063] The vapor-phase oxidized titanium dioxide was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 25%. The pH value was controlled at 10.3 with a mass concentration of 16% sodium hydroxide solution. After aging for 20 minutes, 216g / L sodium hexametaphosphate (the weight of P2O5 in the sodium hexametaphosphate was 0.25%) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 56°C and the entire coating process was carried out at this temperature.

[0064] 2) Coating the first layer of alumina under acidic conditions

[0065] The pH was adjusted to 6.0 with a 16% hydrochloric acid solution and matured for 20 minutes. Within 0.8 hours, sodium aluminate with a concentration of 188 g / L calculated as Al2O3 was added to the slurry, with the amount of sodium aluminate added being 0.58% by weight of Al2O3 relative to the weight of TiO2 in the sodium aluminate. At the same time, aluminum sulfate with a concentration of 102 g / L calculated as Al2O3 was used to control the pH value to 6.0. After the addition was completed, the slurry was matured for 0.5 hours.

[0066] 3) Coating with a second layer of loose alumina

[0067] After aging for 0.5 h, the pH was adjusted to 8.2 with a 16% hydrochloric acid solution and aged for 20 min; within 0.8 h, sodium aluminate with a concentration of 188 g / L in terms of Al2O3 was added to the slurry, the amount of sodium aluminate added being 1.0% by weight of Al2O3 in the sodium aluminate relative to the TiO2, and aluminum sulfate with a concentration of 102 g / L in terms of Al2O3 was used to control the pH value to 8.2. After the addition was completed, the slurry was aged for 0.5 h; 4) the third layer of loose silicon oxide was coated with a 16% hydrochloric acid solution with a pH value of 5.2 and aged for 20 min; within 1.3 h, sodium silicate solution with a concentration of 212 g / L in terms of SiO2 was added to the slurry based on the SiO2 relative to the TiO2 relative to 3.2% by weight of the sodium silicate, and the pH value was controlled to 5.2 with a 16% hydrochloric acid solution and aged for 0.5 h;

[0068] 5) Coating the fourth layer of loose alumina

[0069] The pH value was controlled at 8.2 using 16% sodium hydroxide by mass and matured for 20 minutes. Within 0.8 hours, sodium aluminate with a concentration of 188 g / L calculated as Al2O3 was added to the slurry, and the amount of sodium aluminate added was 0.8% by weight of Al2O3 to TiO2 in the sodium aluminate. At the same time, aluminum sulfate with a concentration of 102 g / L calculated as Al2O3 was used to control the pH value at 8.2 and matured for 0.5 hours. After washing, filtering, drying, and gas powdering, the comparative product was obtained.

[0070] Comparative Example 2

[0071] In the comparative example, the first layer is not coated with a dense aluminum film, and is directly coated with the second, third, and fourth layers of the film in Example 3. The parameters of the oxidation reaction generator are controlled in the same manner as in Example 3. The steps are as follows:

[0072] 1) Titanium dioxide dispersion treatment

[0073] The vapor-phase oxidized titanium dioxide was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 25%. The pH value was controlled at 10.3 with a mass concentration of 16% sodium hydroxide solution. After aging for 20 minutes, 216g / L sodium hexametaphosphate (the weight of P2O5 in the sodium hexametaphosphate was 0.25%) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 56°C and the entire coating process was carried out at this temperature.

[0074] 2) Coating the first layer of loose alumina

[0075] The pH was adjusted to 8.2 using a 16% hydrochloric acid solution and the mixture was aged for 20 minutes. Within 0.8 hours, 188 g / L of sodium aluminate (calculated as Al2O3) was added to the slurry, with the amount of sodium aluminate added being 1.0% by weight of Al2O3 relative to the weight of TiO2 in the sodium aluminate. At the same time, the pH was controlled at 8.2 using 102 g / L of aluminum sulfate (calculated as Al2O3). After the addition was complete, the mixture was aged for 0.5 hours.

[0076] 3) Coating with a second layer of loose silicon oxide

[0077] The pH value was adjusted to 5.2 with a 16% mass concentration hydrochloric acid solution and matured for 20 minutes; within 1.3 hours, a sodium silicate solution with a concentration of 212 g / L in terms of SiO2 was added to the slurry, so that SiO2 accounted for 3.2% by weight of TiO2 in the sodium silicate, while the pH value was controlled to 5.2 with a 16% mass concentration hydrochloric acid solution and matured for 0.5 hours;

[0078] 4) Coating the fourth layer of loose alumina

[0079] The pH value was controlled at 8.2 using 16% sodium hydroxide by mass and matured for 20 minutes. Within 0.8 hours, sodium aluminate with a concentration of 188 g / L calculated as Al2O3 was added to the slurry, and the amount of sodium aluminate added was 0.8% by weight of Al2O3 to TiO2 in the sodium aluminate. At the same time, aluminum sulfate with a concentration of 102 g / L calculated as Al2O3 was used to control the pH value at 8.2 and matured for 0.5 hours. After washing, filtering, drying, and gas powdering, the comparative product was obtained.

[0080] Comparative Example 3

[0081] Comparative Example: After the gas phase oxidation reaction, aluminum chloride was added to the cooling section at a flow rate of 120 kg / h. The steps are as follows:

[0082] 1) Titanium dioxide first layer of alumina vapor coating

[0083] Titanium dioxide is produced by vapor-phase oxidation of refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the refined titanium tetrachloride flow rate in the oxidation reactor is controlled at 6000 kg / h and a pressure of 0.65 MPa; the oxygen flow rate is controlled at 1318 kg / h and an oxygen pressure of 1.3 MPa. The hot oxygen is preheated to 1750°C in the oxidation reactor using heat generated by toluene combustion, causing a vapor-phase oxidation reaction between the titanium tetrachloride and oxygen. Aluminum trichloride, potassium chloride, and deionized water are simultaneously added, with the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride, and deionized water being 1000:10, 1000:1, and 1000:6, respectively. The preheated vapor aluminum trichloride is added to the cooling section after the vapor-phase oxidation reaction of the refined titanium tetrachloride in the oxidation reactor, where the temperature of the vapor-phase oxidation titanium tetrachloride product is 1550°C. The preheated vapor aluminum trichloride has a pressure of 600 kPa and a temperature of 810°C. When adding gaseous aluminum chloride, the aluminum chloride flow rate is controlled at 120 kg / h and the pressure is controlled at 1.1 MPa. After the gaseous oxidation reaction is completed, the aluminum chloride enters the bag filter through the cooler.

[0084] 2) Titanium dioxide dispersion treatment

[0085] The titanium dioxide vapor-coated with alumina was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 25%. The pH value was controlled at 10.3 with a 16% sodium hydroxide solution. After aging for 20 minutes, 216 g / L sodium hexametaphosphate (based on the weight of P2O5 in the sodium hexametaphosphate accounting for 0.25% of the weight of TiO2) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 56°C and the entire coating process was carried out at this temperature.

[0086] 3) Coating with a second layer of loose alumina

[0087] The pH was adjusted to 8.2 using a 16% hydrochloric acid solution and the mixture was aged for 20 minutes. Within 0.8 hours, 188 g / L of sodium aluminate (calculated as Al2O3) was added to the slurry, with the amount of sodium aluminate added being 1.0% by weight of Al2O3 relative to the weight of TiO2 in the sodium aluminate. At the same time, the pH was controlled at 8.2 using 102 g / L of aluminum sulfate (calculated as Al2O3). After the addition was complete, the mixture was aged for 0.5 hours.

[0088] 4) Coating the third layer of loose silicon oxide

[0089] The pH value was adjusted to 5.2 with a 16% mass concentration hydrochloric acid solution and matured for 20 minutes; within 1.3 hours, a sodium silicate solution with a concentration of 212 g / L in terms of SiO2 was added to the slurry, so that SiO2 accounted for 3.2% by weight of TiO2 in the sodium silicate, while the pH value was controlled to 5.2 with a 16% mass concentration hydrochloric acid solution and matured for 0.5 hours;

[0090] 5) Coating the fourth layer of loose alumina

[0091] The pH value was controlled at 8.2 using 16% sodium hydroxide by mass and matured for 20 minutes. Within 0.8 hours, sodium aluminate with a concentration of 188 g / L calculated as Al2O3 was added to the slurry, and the amount of sodium aluminate added was 0.8% by weight of Al2O3 to TiO2 in the sodium aluminate. At the same time, aluminum sulfate with a concentration of 102 g / L calculated as Al2O3 was used to control the pH value at 8.2 and matured for 0.5 hours. After washing, filtering, drying, and gas powdering, the comparative product was obtained.

[0092] Comparative Example 4

[0093] Comparative Example Compared with Example 3, the second layer is not covered with loose aluminum film, and the steps are as follows:

[0094] 1) Titanium dioxide first layer of alumina vapor coating

[0095] Titanium dioxide is produced by vapor-phase oxidation of refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the refined titanium tetrachloride flow rate in the oxidation reactor is controlled at 6000 kg / h and a pressure of 0.65 MPa; the oxygen flow rate is controlled at 1318 kg / h and an oxygen pressure of 1.3 MPa. The hot oxygen is preheated to 1750°C in the oxidation reactor using heat generated by toluene combustion, causing a vapor-phase oxidation reaction between the titanium tetrachloride and oxygen. Aluminum trichloride, potassium chloride, and deionized water are simultaneously added, with the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride, and deionized water being 1000:10, 1000:1, and 1000:6, respectively. The preheated vapor aluminum trichloride is added to the cooling section after the vapor-phase oxidation reaction of the refined titanium tetrachloride in the oxidation reactor, where the temperature of the vapor-phase oxidation titanium tetrachloride product is 1550°C. The preheated vapor aluminum trichloride has a pressure of 600 kPa and a temperature of 810°C. When adding gaseous aluminum chloride, the aluminum chloride flow rate is controlled at 38 kg / h and the pressure is controlled at 1.1 MPa. After the gaseous oxidation reaction is completed, the gas enters the bag filter through the cooler.

[0096] 2) Titanium dioxide dispersion treatment

[0097] The titanium dioxide vapor-coated with alumina was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 25%. The pH value was controlled at 10.3 with a 16% sodium hydroxide solution. After aging for 20 minutes, 216 g / L sodium hexametaphosphate (based on the weight of P2O5 in the sodium hexametaphosphate accounting for 0.25% of the weight of TiO2) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 56°C and the entire coating process was carried out at this temperature.

[0098] 3) Coating with a second layer of loose silicon oxide

[0099] The pH value was adjusted to 5.2 with a 16% mass concentration hydrochloric acid solution and matured for 20 minutes; within 1.3 hours, a sodium silicate solution with a concentration of 212 g / L in terms of SiO2 was added to the slurry, so that SiO2 accounted for 3.2% by weight of TiO2 in the sodium silicate, while the pH value was controlled to 5.2 with a 16% mass concentration hydrochloric acid solution and matured for 0.5 hours;

[0100] 4) Coating the third layer of loose alumina

[0101] The pH value was controlled at 8.2 using 16% sodium hydroxide by mass and matured for 20 minutes. Within 0.8 hours, sodium aluminate with a concentration of 188 g / L calculated as Al2O3 was added to the slurry, and the amount of sodium aluminate added was 0.8% by weight of Al2O3 to TiO2 in the sodium aluminate. At the same time, aluminum sulfate with a concentration of 102 g / L calculated as Al2O3 was used to control the pH value at 8.2 and matured for 0.5 hours. After washing, filtering, drying, and gas powdering, the comparative product was obtained.

[0102] Comparative Example 5

[0103] Comparative Example Compared with Example 3, without coating the third loose silicon film, the steps are as follows:

[0104] 1) Titanium dioxide first layer of alumina vapor coating

[0105] Titanium dioxide is produced by vapor-phase oxidation of refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the refined titanium tetrachloride flow rate in the oxidation reactor is controlled at 6000 kg / h and a pressure of 0.65 MPa; the oxygen flow rate is controlled at 1318 kg / h and an oxygen pressure of 1.3 MPa. The hot oxygen is preheated to 1750°C in the oxidation reactor using heat generated by toluene combustion, causing a vapor-phase oxidation reaction between the titanium tetrachloride and oxygen. Aluminum trichloride, potassium chloride, and deionized water are simultaneously added, with the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride, and deionized water being 1000:10, 1000:1, and 1000:6, respectively. The preheated vapor aluminum trichloride is added to the cooling section after the vapor-phase oxidation reaction of the refined titanium tetrachloride in the oxidation reactor, where the temperature of the vapor-phase oxidation titanium tetrachloride product is 1550°C. The preheated vapor aluminum trichloride has a pressure of 600 kPa and a temperature of 810°C. When adding gaseous aluminum chloride, the aluminum chloride flow rate is controlled at 38 kg / h and the pressure is controlled at 1.1 MPa. After the gaseous oxidation reaction is completed, the gas enters the bag filter through the cooler.

[0106] 2) Titanium dioxide dispersion treatment

[0107] The titanium dioxide vapor-coated with alumina was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 25%. The pH value was controlled at 10.3 with a 16% sodium hydroxide solution. After aging for 20 minutes, 216 g / L sodium hexametaphosphate (based on the weight of P2O5 in the sodium hexametaphosphate accounting for 0.25% of the weight of TiO2) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 56°C and the entire coating process was carried out at this temperature.

[0108] 3) Coating with a second layer of loose alumina

[0109] After aging for 0.5h, adjust the pH to 8.2 with a hydrochloric acid solution with a mass concentration of 16% and age for 20min; add 188g / L of sodium aluminate in terms of Al2O3 to the slurry within 0.8h, and the amount of sodium aluminate added is 1.0% of the weight of Al2O3 in sodium aluminate to the TiO2. At the same time, use 102g / L of aluminum sulfate in terms of Al2O3 to control the pH value to 8.2. After the addition is completed, age. 0.5h; 4) within 0.8h, sodium aluminate with a concentration of 188g / L calculated as Al2O3 is added to the slurry of the third loose alumina coating, the amount of sodium aluminate added is 0.8% by weight of Al2O3 to TiO2 in sodium aluminate, and at the same time, aluminum sulfate with a concentration of 102g / L calculated as Al2O3 is used to control the pH value to 8.2, and mature for 0.5h; after washing, filtering, drying, and gas powdering, the comparative product is obtained.

[0110] Comparative Example 6

[0111] Comparative Example Compared with Example 3, without coating the fourth layer of aluminum film, the steps are as follows:

[0112] 1) Titanium dioxide first layer of alumina vapor coating

[0113] Titanium dioxide is produced by vapor-phase oxidation of refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the refined titanium tetrachloride flow rate in the oxidation reactor is controlled at 6000 kg / h and a pressure of 0.65 MPa; the oxygen flow rate is controlled at 1318 kg / h and an oxygen pressure of 1.3 MPa. The hot oxygen is preheated to 1750°C in the oxidation reactor using heat generated by toluene combustion, causing a vapor-phase oxidation reaction between the titanium tetrachloride and oxygen. Aluminum trichloride, potassium chloride, and deionized water are simultaneously added, with the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride, and deionized water being 1000:10, 1000:1, and 1000:6, respectively. The preheated vapor aluminum trichloride is added to the cooling section after the vapor-phase oxidation reaction of the refined titanium tetrachloride in the oxidation reactor, where the temperature of the vapor-phase oxidation titanium tetrachloride product is 1550°C. The preheated vapor aluminum trichloride has a pressure of 600 kPa and a temperature of 810°C. When adding gaseous aluminum chloride, the aluminum chloride flow rate is controlled at 38 kg / h and the pressure is controlled at 1.1 MPa. After the gaseous oxidation reaction is completed, the gas enters the bag filter through the cooler.

[0114] 2) Titanium dioxide dispersion treatment

[0115] The titanium dioxide vapor-coated with alumina was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 25%. The pH value was controlled at 10.3 with a 16% sodium hydroxide solution. After aging for 20 minutes, 216 g / L sodium hexametaphosphate (based on the weight of P2O5 in the sodium hexametaphosphate accounting for 0.25% of the weight of TiO2) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 56°C and the entire coating process was carried out at this temperature.

[0116] 3) Coating with a second layer of loose alumina

[0117] After aging for 0.5h, adjust the pH to 8.2 with a hydrochloric acid solution with a mass concentration of 16% and age for 20min; add sodium aluminate with a concentration of 188g / L in terms of Al2O3 to the slurry within 0.8h, and the amount of sodium aluminate added is 1.0% of the weight of Al2O3 in sodium aluminate to the TiO2. At the same time, use aluminum sulfate with a concentration of 102g / L in terms of Al2O3 to control the pH value to 8.2. After the addition is completed, age for 0.5h. ; 4) The third layer of loose silicon oxide was coated with a hydrochloric acid solution with a mass concentration of 16% and the pH value was adjusted to 5.2, and the mixture was aged for 20 minutes; within 1.3 hours, a sodium silicate solution with a SiO2 concentration of 212 g / L was added to the slurry based on the SiO2 content of 3.2% by weight of TiO2 in the sodium silicate, and the pH value was controlled to 5.2 with a hydrochloric acid solution with a mass concentration of 16%, and the mixture was aged for 0.5 hours; after washing, filtering, drying, and gas powdering, the comparative product was obtained.

[0118] Comparative Example 7

[0119] Comparative Example Compared with Example 3, the third loose silicon film is coated under alkaline conditions, and the steps are as follows:

[0120] 1) Titanium dioxide first layer of alumina vapor coating

[0121] Titanium dioxide is produced by vapor-phase oxidation of refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the refined titanium tetrachloride flow rate in the oxidation reactor is controlled at 6000 kg / h and a pressure of 0.65 MPa; the oxygen flow rate is controlled at 1318 kg / h and an oxygen pressure of 1.3 MPa. The hot oxygen is preheated to 1750°C in the oxidation reactor using heat generated by toluene combustion, causing a vapor-phase oxidation reaction between the titanium tetrachloride and oxygen. Aluminum trichloride, potassium chloride, and deionized water are simultaneously added, with the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride, and deionized water being 1000:10, 1000:1, and 1000:6, respectively. The preheated vapor aluminum trichloride is added to the cooling section after the vapor-phase oxidation reaction of the refined titanium tetrachloride in the oxidation reactor, where the temperature of the vapor-phase oxidation titanium tetrachloride product is 1550°C. The preheated vapor aluminum trichloride has a pressure of 600 kPa and a temperature of 810°C. When adding gaseous aluminum chloride, the aluminum chloride flow rate is controlled at 38 kg / h and the pressure is controlled at 1.1 MPa. After the gaseous oxidation reaction is completed, the gas enters the bag filter through the cooler.

[0122] 2) Titanium dioxide dispersion treatment

[0123] The titanium dioxide vapor-coated with alumina was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 25%. The pH value was controlled at 10.3 with a 16% sodium hydroxide solution. After aging for 20 minutes, 216 g / L sodium hexametaphosphate (based on the weight of P2O5 in the sodium hexametaphosphate accounting for 0.25% of the weight of TiO2) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 56°C and the entire coating process was carried out at this temperature.

[0124] 3) Coating with a second layer of loose alumina

[0125] After aging for 0.5 h, the pH was adjusted to 8.2 with a 16% hydrochloric acid solution and aged for 20 min. Within 0.8 h, sodium aluminate with a concentration of 188 g / L in terms of Al2O3 was added to the slurry, with the amount of sodium aluminate added being 1.0% by weight of Al2O3 in the sodium aluminate relative to the TiO2. At the same time, aluminum sulfate with a concentration of 102 g / L in terms of Al2O3 was used to control the pH value to 8.2. The addition was completed and the slurry was aged for 0.5 h. 4) After the third layer of loose silicon oxide was coated under alkaline conditions, a sodium silicate solution with a concentration of 212 g / L in terms of SiO2 was added to the slurry within 1.3 h, with the SiO2 ratio of 3.2% by weight of the TiO2 in the sodium silicate. At the same time, a 16% hydrochloric acid solution was used to control the pH value to 8.2. The slurry was aged for 0.5 h.

[0126] 5) Coating the fourth layer of loose alumina

[0127] The pH value was controlled at 8.2 using 16% sodium hydroxide by mass and matured for 20 minutes. Within 0.8 hours, sodium aluminate with a concentration of 188 g / L calculated as Al2O3 was added to the slurry, and the amount of sodium aluminate added was 0.8% by weight of Al2O3 to TiO2 in the sodium aluminate. At the same time, aluminum sulfate with a concentration of 102 g / L calculated as Al2O3 was used to control the pH value at 8.2 and matured for 0.5 hours. After washing, filtering, drying, and gas powdering, the comparative product was obtained.

[0128] Comparative Example 8

[0129] Comparative Example Compared with Example 3, the third layer of silicon oxide and aluminum oxide mixed film was coated under acidic conditions, and the steps were as follows:

[0130] 1) Titanium dioxide first layer of alumina vapor coating

[0131] Titanium dioxide is produced by vapor-phase oxidation of refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the refined titanium tetrachloride flow rate in the oxidation reactor is controlled at 6000 kg / h and a pressure of 0.65 MPa; the oxygen flow rate is controlled at 1318 kg / h and an oxygen pressure of 1.3 MPa. The hot oxygen is preheated to 1750°C in the oxidation reactor using heat generated by toluene combustion, causing a vapor-phase oxidation reaction between the titanium tetrachloride and oxygen. Aluminum trichloride, potassium chloride, and deionized water are simultaneously added, with the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride, and deionized water being 1000:10, 1000:1, and 1000:6, respectively. The preheated vapor aluminum trichloride is added to the cooling section after the vapor-phase oxidation reaction of the refined titanium tetrachloride in the oxidation reactor, where the temperature of the vapor-phase oxidation titanium tetrachloride product is 1550°C. The preheated vapor aluminum trichloride has a pressure of 600 kPa and a temperature of 810°C. When adding gaseous aluminum chloride, the aluminum chloride flow rate is controlled at 38 kg / h and the pressure is controlled at 1.1 MPa. After the gaseous oxidation reaction is completed, the gas enters the bag filter through the cooler.

[0132] 2) Titanium dioxide dispersion treatment

[0133] The titanium dioxide vapor-coated with alumina was slurried in distilled water to obtain a titanium dioxide slurry with a mass concentration of 25%. The pH value was controlled at 10.3 with a 16% sodium hydroxide solution. After aging for 20 minutes, 216 g / L sodium hexametaphosphate (based on the weight of P2O5 in the sodium hexametaphosphate accounting for 0.25% of the weight of TiO2) was added and dispersed for 0.5 hours, followed by sand milling. The slurry was heated to 56°C and the entire coating process was carried out at this temperature.

[0134] 3) Coating with a second layer of loose alumina

[0135] After aging for 0.5h, adjust the pH to 8.2 with a hydrochloric acid solution with a mass concentration of 16% and age for 20min; add 188g / L of sodium aluminate in terms of Al2O3 to the slurry within 0.8h, and the amount of sodium aluminate added is 1.0% of the weight of Al2O3 in sodium aluminate to the TiO2. At the same time, use 102g / L of aluminum sulfate in terms of Al2O3 to control the pH value to 8.2. After the addition is completed, age for 0.5h. h; 4) coating the third layer of silicon oxide and aluminum oxide mixed film under acidic conditions, adjusting the pH to 5.2 with a 16% mass concentration hydrochloric acid solution and aging for 20 minutes; adding a sodium silicate solution with a concentration of 212 g / L (based on SiO2) and a SiO2 to TiO2 ratio of 3.2% by weight to the slurry over 1.3 hours, and simultaneously controlling the pH to 5.2 with aluminum sulfate with a concentration of 102 g / L (based on Al2O3) and aging for 0.5 hours;

[0136] 5) Coating the fourth layer of loose alumina

[0137] The pH value was controlled at 8.2 using 16% sodium hydroxide by mass and matured for 20 minutes. Within 0.8 hours, sodium aluminate with a concentration of 188 g / L calculated as Al2O3 was added to the slurry, and the amount of sodium aluminate added was 0.8% by weight of Al2O3 to TiO2 in the sodium aluminate. At the same time, aluminum sulfate with a concentration of 102 g / L calculated as Al2O3 was used to control the pH value at 8.2 and matured for 0.5 hours. After washing, filtering, drying, and gas powdering, the comparative product was obtained.

[0138] The main indicators and application indicators of the above-mentioned examples and comparative examples are shown in Table 1.

[0139] Table 1 Main indicators and application indicators of the products of the embodiments and comparative examples

[0140]

[0141] The results in Table 1 demonstrate that the samples prepared by the present invention achieve optimal product and application indicators. Comparative Example 1, coated under acidic conditions, exhibits inferior hiding power and tinting power compared to Example 3, and slightly lower acid solubility. This indicates that vapor-phase coating of the first aluminum layer is more uniform, dense, and continuous than that coated under acidic conditions, with less fineness, a thinner coating layer, and better UV resistance. Comparative Example 2 exhibits inferior tinting power, hiding power, oil absorption, and acid solubility compared to Example 3. It can be seen that the coating of the first layer of dense film and the coating of the loose film not only affect the hiding power of the product, but also have a greater impact on the product's color-reducing power, oil absorption, and acid solubility. Although the oil absorption of Comparative Example 3 is improved compared with Example 3, the fineness is significantly increased and the anti-ultraviolet ability is reduced. The amount of vapor-phase aluminum oxide film is too much, and the generation of coarse particles has an impact on subsequent coating and product performance. The hiding power and oil absorption of Comparative Example 4 are most significantly different from those of Example 3. The hydroxylated aluminum ions coated in Example 3 can prevent the polymerization of silica gel particles, thereby improving the product's hiding power and oil absorption. The hiding power, oil absorption and acid solubility of Example 5 are worse than those of Example 3. The coating of the loose porous sponge-like silicon oxide film plays an important role in the product performance; in Comparative Example 6, the outer layer of the silicon oxide film is not coated with aluminum oxide, and the filter cake has poor thixotropy, which is not conducive to industrial production, and its dispersibility in cosmetics is not good; Comparative Example 7 is compared with Example 3, which shows that the covering power and oil absorption of the loose film coated under alkaline conditions are better than those of the product under acidic conditions; Comparative Example 8 is worse than Example 3, which shows that Example 3 is more excellent in terms of the coating color-reducing power, hiding power and oil absorption performance compared with the mixed film of silicon oxide and aluminum oxide.

[0142] The above are merely specific embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption, characterized by: 1) Titanium dioxide first layer of alumina vapor coating Titanium dioxide is prepared by a vapor-phase oxidation process using refined titanium tetrachloride produced by boiling chlorination. During the vapor-phase oxidation process, the flow rate of refined titanium tetrachloride introduced into an oxidation reaction generator is controlled to be 5500 kg / h to 6500 kg / h and the pressure is controlled to be 0.5 MPa to 0.8 MPa; the flow rate of oxygen is simultaneously controlled to be 1212 kg / h to 1403 kg / h and the oxygen pressure is controlled to be 1.2 MPa to 1.4 MPa; the hot oxygen is preheated to 1700° C. to 1800° C. in an oxidation reactor using heat generated by toluene combustion, so that the titanium tetrachloride and oxygen undergo a vapor-phase oxidation reaction, and aluminum trichloride, potassium chloride and deionized water are simultaneously added, wherein the mass ratios of titanium tetrachloride to aluminum trichloride, potassium chloride and deionized water are 1000:10, 1000:1 and 1000:6, respectively. In the cooling section after the vapor-phase oxidation reaction of refined titanium tetrachloride in the oxidation reaction generator, where the temperature of titanium dioxide produced by vapor-phase oxidation of titanium tetrachloride is between 1500 and 1600°C, preheated vapor-phase aluminum trichloride is added at a flow rate of 25 to 50 kg / h and a pressure of 1.0 to 1.2 MPa to vapor-coat the titanium dioxide with aluminum oxide; 2) Titanium dioxide dispersion treatment The titanium dioxide vapor-coated with alumina is added to distilled water for slurrying, and the pH value is controlled at 10.0-10.5 with an inorganic alkali solution. After aging for 20 minutes, a sodium hexametaphosphate solution is added for dispersion treatment for 0.5 hours, followed by sand grinding and stirring to obtain a titanium dioxide dispersion slurry. The titanium dioxide dispersion slurry is heated to 50-60° C. and maintained at this temperature throughout the coating process. 3) Titanium dioxide wet coating The titanium dioxide dispersion slurry of step 2) is subjected to wet coating. First, a second loose aluminum oxide film is coated on the surface of the titanium dioxide with a basic aluminum salt. The amount of the basic aluminum salt solution added is 0.8% to 1.2% by weight of Al2O3 in the basic aluminum salt relative to the weight of TiO2. Then, a third loose silicon oxide film is coated on the surface of the titanium dioxide using a silicate solution, wherein the amount of the silicate added is 2% to 4% by weight of SiO2 in the silicate relative to the weight of TiO2; finally, a fourth loose aluminum oxide film is coated on the surface of the titanium dioxide using a basic aluminum salt, wherein the amount of the basic aluminum salt solution added is 0.6% to 1.0% by weight of Al2O3 in the basic aluminum salt relative to the weight of TiO2; When coating the second and fourth loose alumina layers, the titanium dioxide dispersion slurry is controlled to have a pH value of 7.5 to 8.5 with an inorganic acid solution and an inorganic base solution, respectively, and aged for 20 minutes; basic aluminum salt is added dropwise within 0.5 to 1.0 hours, and the pH value is controlled to 7.5 to 8.5 with an acidic aluminum salt, and aged for 0.5 hours to obtain a loose alumina film; When coating the third loose silicon oxide layer, the titanium dioxide slurry coated with the second loose aluminum oxide film is controlled to have a pH value of 4.0 to 6.0 with an inorganic acid solution and aged for 20 minutes; a silicate solution is added dropwise within 1.0 to 1.5 hours, while controlling the pH value to 4.0 to 6.0 with an inorganic acid solution and aged for 0.5 hours to obtain a third loose silicon oxide film; 4) Titanium dioxide post-treatment The wet-coated slurry was aged for 0.5 h, and then washed, filtered, dried, and air-powdered to obtain titanium dioxide powder for cosmetics with high hiding power and high oil absorption.

2. The method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption according to claim 1, wherein: In step 1), the pressure of the preheated gaseous aluminum chloride is 300 kPa to 900 kPa, and the temperature is 730° C. to 880° C.

3. The method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption according to claim 1, wherein: The basic aluminum salt is at least one of sodium metaaluminate and potassium metaaluminate, and the concentration of the basic aluminum salt is 170 g / L to 200 g / L in terms of Al2O3.

4. The method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption according to claim 1, wherein: During the beating treatment, the mass concentration of the titanium dioxide slurry obtained is 20% to 30%; In step 2), the amount of sodium hexametaphosphate solution added is 0.2% to 0.3% by weight based on the weight of P2O5 to TiO2, and the concentration of the sodium hexametaphosphate solution is 210 g / L to 220 g / L based on P2O5.

5. The method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption according to claim 3, wherein: The acidic aluminum salt is selected from at least one of aluminum sulfate and aluminum chloride, and the concentration of the acidic aluminum salt is 90 g / L to 110 g / L in terms of Al2O3.

6. The method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption according to claim 1, wherein: In step 3), the silicate is at least one of sodium silicate and potassium silicate; and the silicate concentration is 200 g / L to 220 g / L in terms of SiO2.

7. The method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption according to claim 1, wherein: The inorganic alkali solution is one of sodium hydroxide and potassium hydroxide; the mass concentration of the inorganic alkali solution is 10% to 20%.

8. The method for producing titanium dioxide powder for cosmetics with high hiding power and high oil absorption according to claim 1, wherein: The inorganic acid solution is one of hydrochloric acid or sulfuric acid, and the mass concentration of the inorganic acid solution is 10% to 20%.

Images