Preparation method of composite titanium dioxide for high-performance latex paint

Abstract

The invention discloses a preparation method of composite titanium dioxide for high-performance latex paint, which comprises the following steps: S1, preparing slurry: pulping a titanium dioxide base material with the original grain size of 0.19-0.21 mu m, and then grinding; s2, aluminum silicate coating: adding a soluble silicic acid source, adjusting the pH value to 5-7, then adding aluminum sulfate, and adjusting the pH value to 2-4; repeating the steps until the addition amount of the soluble silicic acid source is 10-15% of the mass of the titanium dioxide base material in terms of silicon dioxide; s3, barium-aluminum coating: adding a certain amount of barium hydroxide to completely precipitate sulfate radicals in the system; and adding aluminum sulfate and barium hydroxide in a parallel flow manner, and curing to form a barium sulfate and aluminum oxide composite coating. The composite titanium dioxide is prepared in a wet deposition coating mode, titanium dioxide and filler are combined through chemical bonds, interfacial compatibility and uniform dispersion are achieved, and the composite titanium dioxide is far superior to a mechanical mixed product in the aspects of covering power, dispersity and the like.

Description

Technical Field

[0001] This invention belongs to the field of composite titanium dioxide technology, and specifically relates to a method for preparing high-performance composite titanium dioxide for latex paint. Background Technology

[0002] Titanium dioxide's excellent properties and applications are well-known, but it is expensive and titanium resources are becoming increasingly scarce. Therefore, composite titanium dioxide, which has the properties of titanium dioxide but is less expensive, is widely favored.

[0003] Composite titanium dioxide is a titanium dioxide substitute produced through composite technology, typically composed of titanium dioxide combined with other functional materials. Compared to traditional titanium dioxide, it offers advantages such as lower cost, better hiding power, and reduced resource consumption. Furthermore, through a special preparation process, composite titanium dioxide exhibits better dispersibility, reducing pigment agglomeration in coatings and thus improving light scattering efficiency, thereby enhancing the uniformity and stability of the coating.

[0004] Currently, most composite titanium dioxide products on the market are produced through mechanical physical mixing. This method makes it difficult to achieve uniform molecular-level dispersion of titanium dioxide and fillers, easily leading to localized aggregation or uneven distribution. This results in significant fluctuations in the whiteness, hiding power, and tinting strength of the composite powder, failing to achieve the stability of pure titanium dioxide or chemically synthesized composite titanium dioxide. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing high-performance composite titanium dioxide for latex paint in order to overcome the shortcomings of the prior art.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for preparing high-performance composite titanium dioxide for latex paint includes the following steps:

[0008] S1. Preparation of slurry: Titanium dioxide-based material with a primary grain size of 0.19–0.21 μm is used, slurried, and then ground;

[0009] S2. Aluminum silicate coating: Add a soluble silica source to the ground slurry, adjust the pH to 5-7, then add aluminum sulfate and adjust the pH to 2-4; repeat the above steps of adding the soluble silica source and aluminum sulfate until the amount of the soluble silica source added, based on silicon dioxide, is 10-15% of the mass of the titanium dioxide base material;

[0010] S3. Barium-aluminum coating: A certain amount of barium hydroxide is added to completely precipitate the sulfate ions in the system; then aluminum sulfate and barium hydroxide are added in parallel flow, and after aging, a composite coating of barium sulfate and aluminum oxide is formed; when added in parallel flow, the amount of aluminum sulfate added is 3-5% of the mass of the titanium dioxide base material, calculated as alumina, and the amount of barium hydroxide added is 5-8% of the mass of the titanium dioxide base material, calculated as barium oxide.

[0011] Preferably, the grinding in step S1 is carried out by sand milling until the particle size of the slurry is 0.310 to 0.320 μm, which is obtained by laser particle size analyzer; a dispersant is added during the sand milling process.

[0012] Preferably, the dispersant is selected from at least one of Na2SiO3, (NaPO3)6, and sodium polycarboxylate.

[0013] Preferably, in step S1, the slurry concentration is adjusted to 500-700 g / L before grinding and to 300-450 g / L after grinding, wherein the slurry concentration is based on the titanium dioxide content in the slurry.

[0014] Preferably, the coating temperature in steps S2 and S3 is 40–55°C.

[0015] Preferably, the soluble silica source in step S2 is sodium silicate and / or potassium silicate.

[0016] Preferably, the soluble silica source in step S2 is added each time for 5 to 9 minutes;

[0017] The aluminum sulfate is added each time at a time of 1 to 3 minutes.

[0018] Preferably, the soluble silica source and the aluminum sulfate are added in a total of 4 to 6 cycles in step S2.

[0019] Preferably, the soluble silica source, aluminum sulfate, and barium hydroxide are added in solution form, and the concentration of the soluble silica source solution is 80-120 g / L (calculated as SiO2).

[0020] The concentration of the aluminum sulfate solution, calculated as Al2O3, is 80–120 g / L.

[0021] The concentration of the barium hydroxide solution, calculated as BaO, is 120–180 g / L.

[0022] Preferably, the aluminum sulfate and barium hydroxide are added in parallel for 40-80 minutes in step S3; the aging time is 20-40 minutes.

[0023] This invention employs a wet deposition coating method to prepare composite titanium dioxide. By chemically bonding titanium dioxide powder and fillers, interfacial compatibility and uniform dispersion are achieved, resulting in superior hiding power and dispersibility compared to mechanically mixed products. Furthermore, by using smaller particle size titanium dioxide as the base material, a special pendulum-type coating, and co-precipitation of barium sulfate and alumina, the total coating amount can reach approximately 22%, resulting in more uniform titanium dioxide particles, better dispersibility in the system, and superior optical properties. Detailed Implementation

[0024] This application provides a method for preparing high-performance composite titanium dioxide for latex paint, comprising the following steps:

[0025] S1. Preparation of slurry: Titanium dioxide base material with a primary grain size of 0.19-0.21 μm is used, slurried, and then ground to a suitable particle size for coating; grinding is preferably carried out by sand milling. In order to prevent agglomeration and promote sand milling, a dispersant can be added. The dispersant can be an inorganic dispersant or an organic dispersant. Preferably, the dispersant is selected from at least one of Na2SiO3, (NaPO3)6, and sodium polycarboxylate; preferably, the slurry particle size is sand milled to 0.310-0.320 μm, which is obtained by laser particle size analyzer.

[0026] Primary particle size analysis typically involves high-intensity grinding and uses an ultraviolet spectrophotometer. The particle size is deduced by measuring the intensity of light reflected and scattered after it strikes the particulate matter, thus detecting the size of fully open primary titanium dioxide particles. Laser particle size analyzers, on the other hand, are based on laser scattering technology. When a laser beam strikes a particulate sample, the particles scatter the light. By collecting and analyzing the scattered light signals, the particle size and distribution can be calculated. Laser particle size analyzers can directly and rapidly analyze abrasive slurries without requiring further high-intensity grinding. Therefore, laser particle size analyzers actually detect small agglomerates of titanium dioxide, not the size of primary titanium dioxide particles.

[0027] Titanium dioxide base materials can be obtained using either the chloride process or the sulfate process, with the chloride process being preferred due to its superior performance. In the preparation of titanium dioxide base materials, different processes can be employed. For example, by adding different amounts of grain refiners to chloride process titanium dioxide, or by adding different amounts of salt treatment agents or using different amounts of calcined seed crystals to sulfate process titanium dioxide, titanium dioxide base materials with different primary particle sizes can be prepared.

[0028] Preferably, the slurry concentration is adjusted to 500–700 g / L before grinding. A higher slurry concentration can increase the grinding rate. During coating, especially for silicon coating, the slurry concentration needs to be reduced to prevent excessive slurry viscosity from affecting the coating. Therefore, the slurry concentration is adjusted to 300–450 g / L after grinding, with the slurry concentration based on the titanium dioxide content in the slurry.

[0029] S2. Aluminum silicate coating: Add a soluble silicate source to the slurry after sand milling, adjust the pH to 5-7, then add aluminum sulfate and adjust the pH to 2-4; repeat the above steps of adding soluble silicate source and aluminum sulfate until the amount of soluble silicate source added is 10-15% of the mass of titanium dioxide base material, based on silicon dioxide; aluminum sulfate and soluble silicate source can react to form aluminum silicate precipitate, which is deposited on the surface of titanium dioxide base material;

[0030] Preferably, the coating temperature is 40–55°C. Using a higher coating temperature can promote coating.

[0031] Preferably, the soluble silica source is sodium silicate and / or potassium silicate.

[0032] Preferably, the soluble silica source is added at a time of 5–9 minutes each time, and the aluminum sulfate is added at a time of 1–3 minutes each time. The total number of times the soluble silica source and aluminum sulfate are added is 4–6.

[0033] S3. Barium-aluminum coating: A certain amount of barium hydroxide is added to completely precipitate sulfate ions in the system. After aluminum silicate coating, a relatively large number of sulfate ions still exist in the system. Therefore, barium hydroxide is first added to react with sulfate ions to form barium sulfate precipitate, reducing the salt ion content in the system. Then, aluminum sulfate and barium hydroxide are added in a parallel flow. After aging, a composite coating of barium sulfate and alumina is formed. When added in a parallel flow, the amount of aluminum sulfate added, calculated as alumina, is 3-5% of the mass of the titanium dioxide base material, and the amount of barium hydroxide added, calculated as barium oxide, is 5-8% of the mass of the titanium dioxide base material.

[0034] Preferably, the coating temperature is 40–55°C to promote coating.

[0035] Preferably, aluminum sulfate and barium hydroxide are added in a co-current manner for 40–80 min; the aging time is 20–40 min. Within this range, barium sulfate and aluminum hydroxide can be fully precipitated.

[0036] As those skilled in the art will understand, the coating process also includes water washing, flash evaporation, and vapor powdering, after which the composite titanium dioxide product is obtained.

[0037] This invention first uses smaller grain size particles for recoating (the primary particle size of conventional coating base materials is generally 0.24–0.29 μm) to prepare composite titanium dioxide, increasing the number of particles for the same mass of titanium dioxide and increasing the scattering rate of titanium dioxide particles, thereby improving the wet hiding power of the formulation. Then, this application employs a special pendulum-type coating method to ensure that the pH is within a certain range, making the negative charge of silicon oxide and the positive charge of aluminum oxide roughly equal, reducing the risk of self-deposition, improving the uniformity of the coating, reducing the specific surface area oil absorption of the product, and thus reducing the viscosity of the system. The resulting nano-alumina silicate coating can improve the whiteness of the paint film, increase dispersion stability, and also give the paint film excellent scrub resistance.

[0038] After coating in step S2, a significant amount of sulfate ions remain in the slurry. Therefore, this application first adds strongly alkaline Ba(OH)2, which serves both as a substitute for the alkaline pH adjuster and as a coating agent, precipitating SO4 from Al2(SO4)3. 2- This significantly reduces the soluble salt content in the slurry, lowers the slurry viscosity, and improves washing efficiency. Then, aluminum sulfate and barium hydroxide are added in a co-current flow to increase the coating amount of barium sulfate and alumina. a SO4 can balance the hiding power and rheology of the formulation, while alumina can improve the dispersibility of the product.

[0039] Therefore, this invention employs a wet deposition coating method to prepare composite titanium dioxide. By chemically bonding titanium dioxide powder and fillers, interfacial compatibility and uniform dispersion are achieved, resulting in superior hiding power and dispersibility compared to mechanically mixed products. Furthermore, by using smaller particle size titanium dioxide as the base material, a special pendulum-type coating, and co-precipitation of barium sulfate and alumina, the total coating amount can reach approximately 22%, resulting in more uniform titanium dioxide particles, better dispersibility in the system, and superior optical performance.

[0040] Preferably, the soluble silica source, aluminum sulfate, and barium hydroxide are added in solution form, wherein the concentration of the soluble silica source solution is 80–120 g / L (calculated as SiO2); the concentration of the aluminum sulfate solution is 80–120 g / L (calculated as Al2O3); and the concentration of the barium hydroxide solution is 120–180 g / L (calculated as BaO).

[0041] Processes not limited in this invention, such as water washing, flash evaporation, and steam powder, are all carried out using conventional methods in the field.

[0042] Example 1

[0043] (1) Preparation of base material

[0044] Take titanium dioxide base material with a grain size of 0.205μm, slurry it, adjust the slurry concentration to 600g / L, then add (NaPO3)6 dispersant and sand mill it until the particle size is 0.318μm.

[0045] (2) Encapsulation

[0046] The titanium dioxide slurry concentration was adjusted to 307 g / L, the temperature to 50℃, and the pH to 1.72. Na₂SiO₃ was added to adjust the pH to 6 over 7 minutes at a concentration of 2%. Al₂(SO₄)₃ was added to adjust the pH to 3 over 2 minutes at a concentration of 0.4%. Na₂SiO₃ was then added again to adjust the pH to 6 over 7 minutes at a concentration of 2%. Al₂(SO₄)₃ was added again to adjust the pH to 3 over 2 minutes at a concentration of 0.4%. The pH was then adjusted further by adding more Na₂SiO₃. 3. Add 0.4% Al2(SO4)3 for 2 min; continue adding Na2SiO3 to adjust pH to 6 for 7 min, adding 2% Na2SiO3; add Al2(SO4)3 to adjust pH to 3 for 2 min, adding 0.4% Al2(SO4)3; continue adding Na2SiO3 to adjust pH to 6 for 7 min, adding 2% Na2SiO3; add Al2(SO4)3 to adjust pH to 3 for 2 min, adding 0.4% Al2(SO4)3; add 3% Ba(OH)2 for 20 min; add 7.2% Ba(OH)2 and 4.8% Al2(SO4)3 in a co-current flow for 60 min, then homogenize for 30 min; and then proceed with water washing, flash evaporation, and steam evaporation to obtain the product.

[0047] Example 2

[0048] (1) Preparation of base material

[0049] Take titanium dioxide base material with a grain size of 0.207μm, slurry it, adjust the slurry concentration to 600g / L, and then add (NaPO3)6 dispersant for sand milling until the particle size is 0.313μm.

[0050] (2) Encapsulation

[0051] The titanium dioxide slurry concentration was adjusted to 310 g / L, the temperature to 47℃, and the pH to 1.96. Na₂SiO₃ was added to adjust the pH to 6 for 7 min (1.9% Na₂SiO₃ added). Al₂(SO₄)₃ was added to adjust the pH to 3 for 2 min (0.4% Al₂(SO₄)₃ added). Na₂SiO₃ was then added again to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added again to adjust the pH to 3 for 2 min (0.4% Al₂(SO₄)₃ added). Na₂SiO₃ was then added again to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added again to adjust the pH to 3 for 2 min (0.4% Al₂(SO₄)₃ added). Na₂SiO₃ was then added again to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). 3. Add 2% of Al2(SO4)3 to adjust the pH to 3 for 2 min, with an addition amount of 0.4% of Al2(SO4)3; continue adding Na2SiO3 to adjust the pH to 6 for 7 min, with an addition amount of 2% of Na2SiO3; add Al2(SO4)3 to adjust the pH to 3 for 2 min, with an addition amount of 0.4% of Al2(SO4)3; continue adding Na2SiO3 to adjust the pH to 6 for 7 min, with an addition amount of 2% of Na2SiO3; add Al2(SO4)3 to adjust the pH to 3 for 2 min, with an addition amount of 0.4% of Al2(SO4)3; add 3.6% of Ba(OH)2 for 20 min; add 5.4% of Ba(OH)2 and 3.6% of Al2(SO4)3 in a co-current flow for 60 min, then homogenize for 30 min; wash with water, flash evaporate, and steam to obtain the product.

[0052] Example 3

[0053] (1) Preparation of base material

[0054] Take titanium dioxide base material with a grain size of 0.199μm, slurry it, adjust the slurry concentration to 600g / L, then add (NaPO3)6 dispersant and sand mill it until the particle size is 0.315μm.

[0055] (2) Encapsulation

[0056] The titanium dioxide slurry concentration was adjusted to 316 g / L, the temperature to 52℃, and the pH to 1.73. Na₂SiO₃ was added to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added to adjust the pH to 3 for 2 min (0.4% Al₂(SO₄)₃ added). Na₂SiO₃ was added again to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added again to adjust the pH to 3 for 2 min (0.4% Al₂(SO₄)₃ added). Na₂SiO₃ was added again to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added again to adjust the pH to 3 for 2 min (2% Al₂(SO₄)₃ added). 4) Add 0.4% of Na2SiO3; continue adding Na2SiO3 to adjust the pH to 6 for 7 min, with a Na2SiO3 addition amount of 2%; add Al2(SO4)3 to adjust the pH to 3 for 2 min, with an Al2(SO4)3 addition amount of 0.4%; continue adding Na2SiO3 to adjust the pH to 6 for 7 min, with a Na2SiO3 addition amount of 2%; add Al2(SO4)3 to adjust the pH to 3 for 2 min, with an Al2(SO4)3 addition amount of 0.4%; add 3% Ba(OH)2 for 20 min; add 7.2% Ba(OH)2 and 4.8% Al2(SO4)3 in a co-current flow for 60 min, and homogenize for 30 min; wash with water, flash evaporate, and steam to obtain the product.

[0057] Comparative Example 1 (Normal Grain Size)

[0058] (1) Preparation of base material

[0059] Take titanium dioxide base material with a grain size of 0.255μm, slurry it, adjust the slurry concentration to 600g / L, and then add (NaPO3)6 dispersant for sand milling until the particle size is 0.314μm.

[0060] (2) Encapsulation

[0061] The titanium dioxide slurry concentration was adjusted to 309 g / L, the temperature to 50℃, and the pH to 1.77. Na₂SiO₃ was added to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added to adjust the pH to 3 for 2 min (0.4% Al₂(SO₄)₃ added). Na₂SiO₃ was added again to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added again to adjust the pH to 3 for 2 min (0.4% Al₂(SO₄)₃ added). Na₂SiO₃ was added again to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added again to adjust the pH to 3 for 2 min (2% Al₂(SO₄)₃ added). Add 0.4% of Na2SiO3; continue adding Na2SiO3 to adjust the pH to 6 for 7 min, with a Na2SiO3 addition amount of 2%; add Al2(SO4)3 to adjust the pH to 3 for 2 min, with an Al2(SO4)3 addition amount of 0.4%; continue adding Na2SiO3 to adjust the pH to 6 for 7 min, with a Na2SiO3 addition amount of 2%; add Al2(SO4)3 to adjust the pH to 3 for 2 min, with an Al2(SO4)3 addition amount of 0.4%; add 3% Ba(OH)2 for 20 min; add 7.2% Ba(OH)2 and 4.8% Al2(SO4)3 in a co-current flow for 60 min, then homogenize for 30 min; wash with water, flash evaporate, and steam to obtain the product.

[0062] Comparative Example 2 (larger grain size)

[0063] (1) Preparation of base material

[0064] Take titanium dioxide base material with a grain size of 0.284μm, slurry it, adjust the slurry concentration to 600g / L, then add (NaPO3)6 dispersant and sand mill it until the particle size is 0.314μm.

[0065] (2) Encapsulation

[0066] The titanium dioxide slurry concentration was adjusted to 321 g / L, the temperature to 50℃, and the pH to 1.77. Na₂SiO₃ was added to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added to adjust the pH to 3 for 2 min (0.4% Al₂(SO₄)₃ added). Na₂SiO₃ was added again to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added again to adjust the pH to 3 for 2 min (0.4% Al₂(SO₄)₃ added). Na₂SiO₃ was added again to adjust the pH to 6 for 7 min (2% Na₂SiO₃ added). Al₂(SO₄)₃ was added again to adjust the pH to 3 for 2 min (2% Al₂(SO₄)₃ added). Add 0.4% of Na2SiO3; continue adding Na2SiO3 to adjust the pH to 6 for 7 min, with a Na2SiO3 addition amount of 2%; add Al2(SO4)3 to adjust the pH to 3 for 2 min, with an Al2(SO4)3 addition amount of 0.4%; continue adding Na2SiO3 to adjust the pH to 6 for 7 min, with a Na2SiO3 addition amount of 2%; add Al2(SO4)3 to adjust the pH to 3 for 2 min, with an Al2(SO4)3 addition amount of 0.4%; add 3% Ba(OH)2 for 20 min; add 7.2% Ba(OH)2 and 4.8% Al2(SO4)3 in a co-current flow for 60 min, then homogenize for 30 min; wash with water, flash evaporate, and steam to obtain the product.

[0067] Comparative Example 3 (Conventional Coating)

[0068] (1) Preparation of base material

[0069] Take titanium dioxide base material with a grain size of 0.203μm, slurry it, adjust the slurry concentration to 600g / L, then add (NaPO3)6 dispersant and sand mill it until the particle size is 0.312μm.

[0070] (2) Encapsulation

[0071] The titanium dioxide slurry concentration was adjusted to 314 g / L, the temperature to 50℃, and the pH to 1.88. 10% Na2SiO3 was added over 30 min, 2% Al2(SO4)3 was added over 20 min, and 3% Ba(OH)2 was added over 20 min. 7.2% Ba(OH)2 and 4.8% Al2(SO4)3 were added concurrently over 60 min, followed by homogenization for 30 min. The product was obtained by washing with water, flash evaporation, and steam evaporation.

[0072] Comparative Example 4 (Conventional Silicon-Aluminum Coating)

[0073] (1) Preparation of base material

[0074] Take titanium dioxide base material with a grain size of 0.203μm, slurry it, adjust the slurry concentration to 600g / L, then add (NaPO3)6 dispersant and sand mill it until the particle size is 0.312μm.

[0075] (2) Encapsulation

[0076] The titanium dioxide slurry concentration was adjusted to 314 g / L, the temperature to 50℃, and the pH to 1.88. 15% Na2SiO3 was added for 30 min, followed by the addition of 12% Al2(SO4)3 for 120 min, and homogenization for 30 min. The final pH was adjusted to 7 with H2SO4 for 60 min, and homogenization for 30 min. The product was obtained by water washing, flash evaporation, and steam evaporation.

[0077] In the water washing section, the filtrate is washed until it reaches a certain conductivity. The washing time and water consumption are shown in Table 1.

[0078] Table 1

[0079]

[0080] The performance of latex paint formulations is shown in Table 2.

[0081] Table 2

[0082]

[0083] As can be clearly seen from Table 2, the overall performance of the embodiment is better than that of the comparative example.

[0084] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A method for preparing high-performance composite titanium dioxide for latex paint, characterized in that, Includes the following steps: S1. Preparation of slurry: Titanium dioxide-based material with a primary grain size of 0.19–0.21 μm is used, slurried, and then ground; S2. Aluminum silicate coating: Add a soluble silica source to the ground slurry, adjust the pH to 5-7, then add aluminum sulfate and adjust the pH to 2-4; repeat the above steps of adding the soluble silica source and aluminum sulfate until the amount of the soluble silica source added, based on silicon dioxide, is 10-15% of the mass of the titanium dioxide base material; S3. Barium-aluminum coating: A certain amount of barium hydroxide is added to completely precipitate the sulfate ions in the system; then aluminum sulfate and barium hydroxide are added in parallel flow, and after aging, a composite coating of barium sulfate and aluminum oxide is formed; when added in parallel flow, the amount of aluminum sulfate added is 3-5% of the mass of the titanium dioxide base material, calculated as alumina, and the amount of barium hydroxide added is 5-8% of the mass of the titanium dioxide base material, calculated as barium oxide.

2. The preparation method of high-performance composite titanium dioxide for latex paint as described in claim 1, characterized in that, The grinding in step S1 is carried out by sand milling until the slurry particle size is 0.310-0.320 μm, which is obtained by laser particle size analyzer; a dispersant is added during the sand milling process.

3. The preparation method of high-performance composite titanium dioxide for latex paint as described in claim 2, characterized in that, The dispersant is selected from at least one of Na2SiO3, (NaPO3)6, and sodium polycarboxylate.

4. The preparation method of high-performance composite titanium dioxide for latex paint as described in claim 1, characterized in that, In step S1, the slurry concentration is adjusted to 500-700 g / L before grinding and to 300-450 g / L after grinding. The slurry concentration is based on the titanium dioxide content in the slurry.

5. The method for preparing high-performance composite titanium dioxide for latex paint as described in claim 1, characterized in that, The coating temperature in steps S2 and S3 is 40–55°C.

6. The method for preparing high-performance composite titanium dioxide for latex paint as described in claim 1, characterized in that, The soluble silica source in step S2 is sodium silicate and / or potassium silicate.

7. The method for preparing high-performance composite titanium dioxide for latex paint as described in claim 1, characterized in that, The soluble silica source mentioned in step S2 is added each time for 5 to 9 minutes; The aluminum sulfate is added each time at a time of 1 to 3 minutes.

8. The method for preparing high-performance composite titanium dioxide for latex paint as described in claim 1, characterized in that, The soluble silica source and the aluminum sulfate are added in a total of 4 to 6 cycles in step S2.

9. The method for preparing high-performance composite titanium dioxide for latex paint as described in claim 1, characterized in that, The soluble silica source, aluminum sulfate, and barium hydroxide are added in solution form, and the concentration of the soluble silica source solution is 80-120 g / L, calculated as SiO2. The concentration of the aluminum sulfate solution, calculated as Al2O3, is 80–120 g / L. The concentration of the barium hydroxide solution, calculated as BaO, is 120–180 g / L.

10. The method for preparing high-performance composite titanium dioxide for latex paint as described in claim 1, characterized in that, In step S3, aluminum sulfate and barium hydroxide are added in a co-current manner for 40–80 min; the aging time is 20–40 min.

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