Preparation method of high-dispersion titanium dioxide
By combining sand milling, vibrating sieving, cyclone classification, and microwave heating treatment, and employing inorganic coating and hydroxyl-containing polybasic acid pretreatment, the problem of poor dispersibility of titanium dioxide was solved, achieving efficient and low-cost preparation of highly dispersed titanium dioxide.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-20
- Publication Date
- 2026-04-28
AI Technical Summary
In the existing technology, titanium dioxide has poor dispersibility, resulting in poor coloring power, hiding power, gloss and weather resistance during application. Moreover, existing methods to enhance dispersibility are energy-intensive, costly or ineffective.
A special base material treatment method is adopted, which combines sand milling, vibrating sieving, cyclone classification and microwave heating treatment. Through inorganic coating, hydroxyl-containing polyacid pretreatment and multiple additions of organic treatment agents, the organic treatment agents are ensured to be uniformly adsorbed on the surface of titanium dioxide and avoid agglomeration.
It significantly improves the dispersibility and stability of titanium dioxide, meets the quality requirements of high-end applications, and reduces energy consumption and costs.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of titanium dioxide preparation technology, and specifically relates to a method for preparing highly dispersed titanium dioxide. Background Technology
[0002] Titanium dioxide is an important white pigment with excellent optical properties and stable chemical properties. It is widely used in coatings, plastics, papermaking, inks, and synthetic fibers. In different systems, titanium dioxide requires good dispersibility; therefore, the requirements for particle size and particle size distribution are very high. Whether using the sulfuric acid process or the chloride process, the crude titanium dioxide (i.e., titanium dioxide base material) typically needs to be dispersed and ground to break up agglomerates and sintered particles, followed by coating, washing, drying, and pulverizing. Often, the grinding process requires two, three, or even more stages, which can lead to over-grinding of small particles and insufficient grinding of large particles. This results in poor dispersibility and flowability of the titanium dioxide. Only titanium dioxide with good dispersibility can exhibit high tinting strength, hiding power, gloss, and weather resistance in applications. Therefore, the dispersibility of titanium dioxide is one of the key factors determining its application performance.
[0003] There are two existing technologies for improving the dispersibility of titanium dioxide. One method involves adding an organic coating agent during air jet milling to coat the particle surface, thereby enhancing the dispersion stability of titanium dioxide through electrostatic or steric hindrance effects. The other method involves adding dispersing equipment (such as high-speed mixers or sand mills) during the use of titanium dioxide to improve its dispersibility. However, this method is energy-intensive and costly, and downstream manufacturers are generally unwilling to choose it. When using the first method, titanium dioxide and the organic coating agent cannot be fully and uniformly mixed in the air jet mill. After crushing, the titanium dioxide particles without the organic coating agent are small, have high surface energy, and tend to agglomerate, affecting dispersibility.
[0004] Therefore, it is necessary to develop a method for preparing highly dispersed titanium dioxide to solve the problems of existing technologies. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing highly dispersed titanium dioxide in order to overcome the shortcomings of the prior art.
[0006] The objective of this invention is achieved through the following technical solution: This invention provides a method for preparing highly dispersed titanium dioxide, comprising the following steps: S1. Take titanium dioxide base material and slurry it. Then, pass the slurry through sand mill, vibrating screen and cyclone classification in sequence to obtain overflow material. S2. Take the overflow material and perform inorganic coating; S3. The inorganically coated slurry is solid-liquid separated, washed with water, and then water and a hydroxyl-containing polybasic acid are added and the slurry is re-pulped; S4. Sand again; S5. Then heat to 70~90℃, add the first organic treatment agent at the same time, mix thoroughly, and then perform microwave heating treatment; S6. The slurry is solid-liquid separated, dried and powdered, with a second organic treatment agent added during the powdering process to obtain highly dispersed titanium dioxide; The steps of sand milling, vibrating sieving and cyclone classification described in step S1 and the step of adding the first organic treatment agent for microwave heating treatment described in step S5 shall be performed once or multiple times. The first organic treatment agent and the second organic treatment agent are independently selected from at least one of polyol compounds.
[0007] Preferably, the titanium dioxide base material is a sulfuric acid process or a chloride process base material; When the titanium dioxide base material is a sulfuric acid process base material, before the pulping, the process further includes a step of crushing the titanium dioxide base material, and between the pulping and the sand milling, a ball milling step is also included; The ball milling process is carried out until the viscosity is ≤200cp and the residue on a 100-mesh sieve is ≤0.1%.
[0008] Preferably, in step S1, the overflow material has a residue of ≥500 mesh sieve <0.01%.
[0009] Preferably, in step S1, the sand is milled to an average particle size of 0.32~0.35μm; The vibrating screen has a mesh size of 300-500 mesh.
[0010] Preferably, the inorganic coating in step S2 is a single aluminum coating, or a composite coating of aluminum and one or more selected from silicon, zirconium, cerium, titanium and phosphorus.
[0011] Preferably, the hydroxyl-containing polyacid in step S3 is at least one selected from malic acid, citric acid, and tartaric acid.
[0012] Preferably, the amount of the hydroxyl-containing polyacid added is 0.1~0.5% of the mass of the titanium dioxide base material.
[0013] Preferably, in step S4, the particles are milled until the average particle size is less than 0.60 μm.
[0014] Preferably, the microwave heating temperature in step S5 is 70~90℃, the power is 100~300w, and the processing time for each step is 20~40min.
[0015] Preferably, the polyol compound is at least one selected from TMP, TME, pentaerythritol, neopentyl glycol, sorbitol, and hexaglycerol.
[0016] Preferably, in step S5, the total amount of the first organic treatment agent added is 0.05~0.3% of the mass of the titanium dioxide base material; In step S6, the amount of the second organic treatment agent added is 0.05~0.3% of the mass of the titanium dioxide base material.
[0017] This application first treats the slurry before coating to remove large particles, then re-slurries the filter cake after coating and washing, and pre-treats it with a hydroxyl-containing polyacid. Combined with sand milling and microwave treatment, the organic treatment agent is more stably attached to the surface of titanium dioxide, which effectively improves the adsorption rate and uniformity of the organic treatment agent on the surface of titanium dioxide, and completely avoids the formation of agglomerates before the titanium dioxide slurry dries, thereby preparing highly dispersed titanium dioxide. Detailed Implementation
[0018] This application provides a method for preparing highly dispersed titanium dioxide, comprising the following steps: S1. Take titanium dioxide base material and slurry it. Then, pass the slurry through sand mill, vibrating screen and cyclone classification in sequence to obtain overflow material. Conventional titanium dioxide base materials generally include sulfuric acid process base materials (produced using the sulfuric acid process) and chloride process base materials (produced using the chloride process). Sulfuric acid process base materials (the finished product after calcination) have a larger particle size and generally need to be crushed first (such as by roller milling) to break down the large particles, then water and dispersant are added to make a slurry, followed by ball milling (using larger grinding media to further grind and crush the large particles, resulting in a relatively larger particle size and wider particle size distribution compared to sand milling) and sand milling to obtain a slurry suitable for coating.
[0019] Chlorination-based materials do not need to be crushed, while oxidized materials (titanium tetrachloride is oxidized to titanium dioxide) are directly mixed with water to form a slurry, and then sand-milled.
[0020] If the sulfuric acid process base material is used in this application, it also needs to undergo crushing and ball milling before sand milling (ball milling is between pulping and sand milling). Preferably, crushing is done using a roller mill with a pressure of 100~180 bar and a roller gap of 1~5 mm. Ball milling is performed until the viscosity is ≤200 cp and the residue on a 100 mesh sieve is ≤0.1%.
[0021] If chlorination-based materials are used, they can be directly pulped and then sand-milled.
[0022] S2. Take the overflow material and perform inorganic coating; S3. After inorganic coating, the slurry is solid-liquid separated, washed with water, and then water and hydroxyl-containing polybasic acid are added and the slurry is re-pulped; S4. Sand again; S5. Then heat to 70~90℃, add the first organic treatment agent at the same time, mix thoroughly, and then perform microwave heating treatment; S6. The slurry is separated into solid and liquid phases, dried, and then vaporized. A second organic treatment agent is added during the vaporization process to obtain highly dispersed titanium dioxide. Step S1, which involves sand milling, vibrating sieving, and cyclone grading, and step S5, which involves adding the first organic treatment agent and performing microwave heating treatment, can be performed once or multiple times; repeated treatment can ensure the treatment effect. The first organic treatment agent and the second organic treatment agent are independently selected from at least one of polyol compounds.
[0023] This application employs a special base material treatment method, combining sand milling, vibrating screen, and hydrocyclone. First, the sand mill uses the high-speed motion of grinding media (such as zirconia beads) to grind and pulverize the material. Simultaneously, sand milling can effectively deagglomerate agglomerates (titanium dioxide base material has a small primary particle size and high specific surface energy, making it prone to agglomeration), allowing titanium dioxide particles to be uniformly dispersed in water. The vibrating screen uses the excitation force of a vibrating motor to make the material vibrate at high frequency on the screen surface, thereby achieving material classification, filtration, or separation, removing impurities and zirconia bead fragments introduced by sand milling. Then, the hydrocyclone is used to further screen the material. Coarse particles are pushed against the wall of the hydrocyclone under the action of centrifugal force and move downward with the outer swirling flow, eventually being discharged from the bottom outlet. Fine particles are subjected to less centrifugal force, and they move more towards the central axis of the hydrocyclone, forming an upward inner swirling flow, and are discharged from the overflow outlet. The material separated by the hydrocyclone has a sieve residue of less than 0.00XX%, and can significantly reduce the particle size distribution.
[0024] Compared to simple sand milling, the core advantage of this combined process lies in constructing a precision production system with "active control and closed-loop optimization." It transforms the single crushing process into an intelligent flow encompassing "grinding-impurity removal-grading-recycling": the sand mill thoroughly refines and uniformly disperses the material; the vibrating screen removes impurities and zirconium bead fragments introduced during sand milling, protecting downstream equipment and improving product purity; the hydrocyclone performs real-time precision grading of the ground material, allowing only qualified overflow fine particles to be output, while unqualified coarse particles are automatically returned to the sand mill for "targeted" regrinding. This not only eliminates over-grinding but also significantly improves grinding efficiency and energy utilization, ensuring a narrower particle size distribution, better consistency, and stability in the final product, thus meeting the stringent quality requirements of high-end applications with higher overall efficiency.
[0025] Preferably, in step S1, the material at the overflow end has a residue of ≥500 mesh sieve <0.01%, under which the titanium dioxide-based slurry is fully dispersed.
[0026] Due to the lattice defects in titanium dioxide, titanium dioxide generally requires inorganic coating treatment, such as mono- or multi-component composite coatings with silicon, aluminum, or zirconium. Silicon and aluminum coatings are more commonly used; silicon coating generally improves the weather resistance of titanium dioxide, while aluminum coating generally improves its dispersibility. During the inorganic coating process, especially with silicon dioxide coating, sodium silicate hydrolyzes to generate Si(OH)4, which condenses to form a ≡Si-O-Si≡ network, adhering to titanium dioxide particles. Furthermore, during alumina coating, aluminum salts hydrolyze to generate Al(OH)3 colloids. These colloid particles undergo condensation through hydroxyl bridging (-Al-OH-Al-), forming a three-dimensional network structure that encapsulates multiple TiO2 particles. Therefore, most inorganic coating processes result in slight agglomeration. Meanwhile, since a large number of salt ions are introduced during inorganic coating, inorganic coating generally requires pressure filtration and water washing. After water washing, the coated particles (silicon oxide / alumina) form hydrogen bonds due to the surface hydroxyl groups (-OH) (titanium dioxide itself has hydroxyl groups on its surface, and the coating process usually introduces more hydroxyl groups with different properties, such as Al–OH, Si–OH). During drying, a "bridging effect" occurs, leading to new micron-sized soft agglomerates.
[0027] Therefore, this application first performs solid-liquid separation and water washing after inorganic coating to thoroughly remove inorganic salts and other impurities from the slurry. Then, a hydroxyl-containing polyacid is added for secondary pulping. This secondary pulping utilizes shear force to disrupt harmful hydrogen bond networks (which exist between the original pigment particles, causing agglomeration and requiring shear force to break them). The hydroxyl-containing polyacid possesses multiple carboxyl and hydroxyl groups, which can promote dispersion through "multi-point anchoring" and "strong solvation." Multiple acidic groups such as carboxylic acids (-COOH) are firmly bonded to the titanium dioxide surface like "anchors" through chemical adsorption or strong ionic bonds. The hydroxyl groups mainly play a role in assisting anchoring (enhancing adsorption through hydrogen bonding) and strengthening solvation. They can form beneficial strong hydrogen bonds with water or polar solvents, allowing the solvation chain of the dispersant to fully extend, thereby forming an effective steric stabilizing layer (steric hindrance) that prevents particles from approaching each other.
[0028] The above illustrates the hydrogen bonding interactions between different objects at different stages of the dispersion process: Phase 1: Crushing and Dispersing (“Breakdown”) The target of secondary pulping is the harmful hydrogen bond network formed between titanium dioxide particles due to their own surface hydroxyl groups, water molecules or impurities. This hydrogen bond network "sticks" the particles together, forming agglomerates.
[0029] The role of secondary pulping shear force: to provide mechanical energy, break the hydrogen bonds between these particles, and break large aggregates into primary particles or smaller aggregates. This process is called "breaking down".
[0030] Phase Two: Stabilization and Prevention of Reunification ("Establishment") The objects to be established are the beneficial hydrogen bond networks formed between dispersant molecules (i.e., polybasic acids containing hydroxyl groups) and the pigment surface, as well as between dispersant molecules and the solvent.
[0031] The promoting effect of hydrogen bonding: Enhanced adsorption: Hydroxyl-containing polyacids form beneficial hydrogen bonds with the hydroxyl groups on the pigment surface through their own hydroxyl and carboxyl groups (existing between the dispersant and titanium dioxide, as well as between the dispersant and the solvent; these bonds help the dispersant to be firmly adsorbed and form a stable barrier to prevent re-agglomeration), thus strengthening its anchoring on the particle surface and making it less prone to desorption.
[0032] Formation of a stabilizing layer: The end of the dispersant extending into the solvent contains polar groups such as hydroxyl groups. These groups form strong hydrogen bonds with the solvent (especially water), allowing the dispersant chains to be fully "wetted" and extended by the solvent, forming a thick, stable solvation layer (hydration layer) around the particles. This generates strong steric hindrance and electrostatic repulsion, preventing the particles from approaching again.
[0033] Preventing reagglomeration: When two well-coated particles come close together, they need to push away this highly solvated stabilizing layer and break a large number of "dispersant-solvent" hydrogen bonds, which requires a lot of energy, so the particles will no longer agglomerate through hydrogen bonds.
[0034] Then, the particles are further depolymerized by collision of the grinding media in a sand mill. The mechanical energy of sand milling not only promotes the activation of the particle surface and allows the coating material to rearrange and fill defects during the collision, but also exposes fresh surfaces, homogenizes hydroxyl sites, improves the coating efficiency of organic treatment agents, and rebuilds the charge-stabilized layer after sand milling, laying a good foundation for subsequent organic coating.
[0035] Then, the first organic treatment agent is added, and the temperature is first raised to achieve uniform heat transfer through thermal convection, ensuring that the treatment agent reacts at the optimal activity temperature. Then, it is treated with microwaves, which not only selectively excites polar molecules (such as the -OH of polyols; in a molecule, the polarity of the bond determines its efficiency of microwave excitation; the OH bond has a very large dipole moment due to the significantly positive charge of hydrogen atoms and the significantly negative charge of oxygen atoms, making it a strongly polar bond; microwaves are high-frequency electromagnetic fields that can force polar bonds in molecules, especially those with large dipole moments, to undergo high-speed rotation, vibration, and orientation changes; this selective excitation provides the activation energy required for the dehydration condensation reaction), but also promotes the dehydration condensation of the treatment agent with the hydroxyl groups on the TiO2 surface. The dehydration condensation reaction is as follows: Ti-OH (titanium dioxide surface) + HO-R (organic treatment agent) → Ti-OR (chemical bond) + H2O. Microwave treatment can also penetrate the slurry, causing water / polar molecules to vibrate at high speed and produce a "micro-explosion" effect, which breaks down the aggregates from the inside. This can significantly shorten the processing time, improve the uniformity of coating, and promote chemical bonding.
[0036] Finally, a second organic treatment agent is added during the powdering process. Its core function is to provide titanium dioxide powder with good compatibility and steric stabilization with the downstream system through dry surface coating, thereby fundamentally solving the problems of its dispersibility and stability in the final application media (such as coatings and inks).
[0037] Therefore, this application first performs special treatment on the slurry before coating to remove large particles, then re-slurries the filter cake after coating and washing, and pre-treats it with a hydroxyl-containing polyacid, and combines sand milling and microwave treatment to make the organic treatment agent more stably attached to the surface of titanium dioxide, effectively improving the adsorption rate and adsorption uniformity of the organic treatment agent on the surface of titanium dioxide, completely avoiding the formation of agglomerates before the titanium dioxide slurry dries, thereby preparing highly dispersed titanium dioxide.
[0038] Preferably, in step S1, the particles are milled to an average particle size of 0.32~0.35μm.
[0039] The vibrating screen has a mesh size of 300-500 mesh. It first screens to remove larger particles, which is beneficial for cyclone classification.
[0040] Preferably, the feed pressure of the hydrocyclone is 0.1~0.5MPa.
[0041] Step S2, the inorganic coating, can employ conventional coating techniques, such as composite coatings of one or more of silicon, aluminum, zirconium, cerium, titanium, and phosphorus. The appropriate material can be selected based on other product requirements. For example, to obtain titanium dioxide with high weather resistance and dispersibility, a silicon-aluminum coating can be used. As is generally known to those skilled in the art, coating titanium dioxide with alumina can improve its dispersibility. Therefore, this application further includes an aluminum coating in its inorganic coating process, specifically a single aluminum coating or a composite coating of aluminum and other elements. The inorganic coating process can utilize existing techniques and will not be elaborated upon here.
[0042] Preferably, in step S1, the pulp concentration is approximately 500-550 g / L to facilitate sand milling. Before coating, the pulp concentration is diluted to 250-350 g / L to facilitate coating. In step S3, the pulp is washed with water until the resistivity is ≥80 Ω·m to ensure that the salt in the filter cake is fully removed. Then, the pulp is re-pulped at a concentration of 400-600 g / L to facilitate subsequent sand milling.
[0043] Preferably, the hydroxyl-containing polyacid in step S3 is at least one selected from malic acid, citric acid, and tartaric acid.
[0044] Preferably, the amount of hydroxyl-containing polyacid added is 0.1~0.5% of the mass of the titanium dioxide base material.
[0045] Preferably, in step S4, the zirconium bead filling rate is ≥75%, and the final grinding is carried out until the average particle size is less than 0.60μm before proceeding to the next step. This is to deagglomerate the large agglomerated particles after coating and washing, and to prevent large-particle materials from entering the next process.
[0046] Preferably, in step S5, the microwave heating temperature is 70~90℃, the power is 100~300w, and the microwave treatment time is 20~40min per cycle, so as to provide sufficient reactivity and promote chemical bonding.
[0047] Preferably, the polyol compound is selected from at least one of TMP, TME, pentaerythritol, neopentyl glycol, sorbitol, and hexaglycerol. In addition to their excellent dispersing properties, these polyol compounds also produce low VOCs after use, making them more environmentally friendly.
[0048] Preferably, the total amount of the first organic treatment agent added in step S5 is 0.05~0.3% of the mass of the titanium dioxide base material.
[0049] Preferably, the amount of the second organic treatment agent added in step S6 is 0.05~0.3% of the mass of the titanium dioxide base material.
[0050] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0051] Example 1 Chlorinated titanium dioxide base material was pulped and the slurry concentration was adjusted to 500 g / L. The slurry was then milled (to an average particle size of 0.34 μm), vibrated and screened (400 mesh), and then classified by a hydrocyclone (column diameter of 50 mm, feed pressure of 0.3 MPa) to prepare a slurry with an overflow material of ≥500 mesh sieve residue of 0.0057%.
[0052] Adjust the slurry concentration to 300 g / L and perform single-aluminum inorganic coating (coating amount is calculated as alumina, which is 3% of the mass of titanium dioxide base material). After coating, wash until the resistivity is 80 Ω·m. Then add citric acid at a mass fraction of 0.25 wt% of titanium dioxide base material, re-slurry to a concentration of 400 g / L, and then sand mill until the average particle size is 0.40 μm.
[0053] The slurry was heated to 70°C, and pentaerythritol (0.1% by mass of titanium dioxide base material) was added. After thorough mixing, it was microwaved for 30 minutes at a power of 200W and a temperature of 80°C. Then, pentaerythritol (0.1% by mass of titanium dioxide base material) was added again, and the mixture was thoroughly mixed. After microwaved again for 30 minutes at a power of 200W and a temperature of 80°C, the mixture was filtered, washed with water, dried, and then steamed. During steaming, TMP (0.1% by mass of titanium dioxide base material) was added.
[0054] Example 2 S1. Take the chlorinated titanium dioxide base material and slurry it. Adjust the slurry concentration to 500 g / L. Then, the slurry is sand-milled (sand-milled to an average particle size of 0.34 μm), vibrated and sieved (400 mesh), and then classified by a hydrocyclone (column diameter of 50 mm, feed pressure of 0.3 MPa) to prepare a slurry with an overflow material of ≥500 mesh sieve residue of 0.0043%.
[0055] S2. Adjust the slurry concentration to 320 g / L and carry out zirconium-aluminum inorganic coating (zirconia coating amount is 0.5% based on zirconium oxide, and aluminum coating amount is 3% based on alumina).
[0056] S3. After coating, wash until the resistivity is 90Ω·m, then add 0.30wt% citric acid, re-pulverize to a concentration of 420g / L, and then sand mill to an average particle size of 0.450μm.
[0057] S4. Heat the slurry to 80°C, add 0.05% neopentyl glycol, mix thoroughly, and microwave for 30 minutes at 200W and 80°C. Then add 0.05% TMP, mix thoroughly, and microwave again for 30 minutes at 300W and 80°C.
[0058] S5. After microwave treatment, filter, wash with water, dry and steam powder, adding 0.2% TME during steam powdering.
[0059] Example 3 Except for step S4, which involves one microwave treatment, the rest is the same as in Example 2. Step S4 is as follows: S4. Heat the slurry to 80℃, add 0.05% neopentyl glycol, mix thoroughly, and microwave for 30 minutes at a power of 200W and a temperature of 80℃.
[0060] Example 4 S1. The titanium dioxide raw material from the sulfuric acid process is first crushed by a roller mill, then pulped to a concentration of 550 g / L, and then ball-milled until the viscosity is ≤200 cp and the residue on a 100-mesh sieve is ≤0.1%. The ball-milled slurry is then sand-milled (to an average particle size of 0.35 μm), vibrated and sieved (450 mesh), and then classified by a hydrocyclone (column diameter of 50 mm, feed pressure of 0.3 MPa) to prepare a slurry with a ≥500-mesh sieve residue of ≥0.0038% after hydrocyclone overflow.
[0061] S2. Adjust the slurry concentration to 280g / L and perform silicon-aluminum inorganic coating (the amount of silicon coating is 2% based on silicon oxide, and the amount of aluminum coating is 3% based on aluminum oxide).
[0062] S3. After coating, wash until the resistivity is 95 Ω·m, then add 0.30 wt% tartaric acid, re-pulverize to a concentration of 450 g / L, and then sand mill to an average particle size of 0.50 μm.
[0063] S4. Heat the slurry to 85℃, add 0.075% pentaerythritol, mix thoroughly, and microwave for 30 minutes at 100W and 85℃. Then add 0.075% hexaglycerol, mix thoroughly, and microwave again for 30 minutes at 100W and 85℃.
[0064] S5. After microwave treatment, filter, wash with water, dry and steam powder, adding 0.15% TMP during steam powdering.
[0065] Example 5 S1. The titanium dioxide raw material from the sulfuric acid process is first crushed by a roller mill, then pulped to a concentration of 550 g / L, and then ball-milled until the viscosity is ≤200 cp and the residue on a 100-mesh sieve is ≤0.1%. The ball-milled slurry is then sand-milled (to an average particle size of 0.35 μm), vibrated and sieved (450 mesh), and then classified by a hydrocyclone (column diameter of 50 mm, feed pressure of 0.3 MPa) to prepare a slurry with a ≥500-mesh sieve residue of ≥0.0038% after hydrocyclone overflow.
[0066] S2. Adjust the slurry concentration to 280g / L and perform single aluminum inorganic coating (the aluminum coating amount is calculated as alumina, which is 3%).
[0067] S3. After coating, wash until the resistivity is 95 Ω·m, then add 0.50 wt% malic acid, re-pulverize to a concentration of 450 g / L, and then sand mill to an average particle size of 0.50 μm.
[0068] S4. Heat the slurry to 85°C, add 0.1% sorbitol, mix thoroughly, and microwave for 30 minutes at a power of 100W and a temperature of 85°C.
[0069] S5. After microwave treatment, filter, wash with water, dry and steam powder, adding 0.3% TMP during steam powdering.
[0070] The inorganic coatings in Examples 1-5 can also be replaced by cerium-phosphorus-aluminum coatings, titanium-silicon-aluminum coatings, etc.
[0071] Comparative Example 1 Take titanium dioxide base material and slurry it. Adjust the slurry concentration to 500 g / L, then sand mill it (sand mill until the average particle size is 0.34 μm). Perform single aluminum inorganic coating (coating amount is 3% based on alumina). After coating, perform pressure filtration and washing, dry and steam powder. Add 0.5% TMP (trimethylolpropane) during steam powdering.
[0072] Comparative Example 2 Take titanium dioxide base material and slurry it. Adjust the slurry concentration to 500 g / L, then sand mill it (sand mill to an average particle size of 0.34 μm). Perform zirconium-aluminum inorganic coating (zirconia coating amount is 0.5% based on zirconium oxide, and aluminum coating amount is 3% based on alumina). After coating, perform pressure filtration and washing, dry and steam powder, adding 0.5% TMP during steam powdering.
[0073] Comparative Example 3 Take titanium dioxide base material and slurry it. Adjust the slurry concentration to 500 g / L, then sand mill it (sand mill to an average particle size of 0.35 μm). Perform silicon-aluminum inorganic coating (the amount of silicon coating is 2% based on silicon oxide, and the amount of aluminum coating is 3% based on aluminum oxide). After coating, perform pressure filtration and washing, dry and steam powder, and add 0.5% TMP during steam powdering.
[0074] Comparative Example 4 Compared with Example 2, step S4 (i.e., the step of adding the first organic treatment agent for microwave treatment) is omitted.
[0075] Comparative Example 5 Compared with Example 2, step S3 (i.e., the step of re-pulping after coating, and directly heating the coated slurry and adding pentaerythritol for microwave treatment) is omitted.
[0076] Dispersion test comparison The dispersibility, water dispersibility (TiO2 content = 70%), and linseed oil dispersibility (TiO2 content = 30%) of the titanium dioxide from the above embodiments and comparative examples were tested. The test results are shown in Table 1. Table 1
[0077] As can be seen from the table, the titanium dioxide in Examples 1-4 exhibits significantly better dispersibility in the alkyd-amino system, water dispersibility, and linseed oil dispersibility than the comparative example.
[0078] 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 highly dispersed titanium dioxide, characterized in that, Includes the following steps: S1. Take titanium dioxide base material and slurry it. Then, pass the slurry through sand mill, vibrating screen and cyclone classification in sequence to obtain the overflow material. S2. Take the overflow material and perform inorganic coating; S3. The inorganically coated slurry is solid-liquid separated, washed with water, and then water and a hydroxyl-containing polybasic acid are added and the slurry is re-pulped; S4. Sand again; S5. Then heat to 70~90℃, add the first organic treatment agent at the same time, mix thoroughly, and then perform microwave heating treatment; S6. The slurry is solid-liquid separated, dried and powdered, with a second organic treatment agent added during the powdering process to obtain highly dispersed titanium dioxide; The steps of sand milling, vibrating sieving and cyclone classification described in step S1 and the step of adding the first organic treatment agent for microwave heating treatment described in step S5 shall be performed once or multiple times. The first organic treatment agent and the second organic treatment agent are independently selected from at least one of polyol compounds.
2. The method for preparing highly dispersed titanium dioxide as described in claim 1, characterized in that, The titanium dioxide base material is a sulfuric acid process or a chloride process base material; When the titanium dioxide base material is a sulfuric acid process base material, before the pulping, the process further includes a step of crushing the titanium dioxide base material, and between the pulping and the sand milling, a ball milling step is also included; The ball milling process is carried out until the viscosity is ≤200cp and the residue on a 100-mesh sieve is ≤0.1%.
3. The method for preparing highly dispersed titanium dioxide as described in claim 1, characterized in that, In step S1, the material at the overflow end has a residue of ≥500 mesh sieve <0.01%.
4. The method for preparing highly dispersed titanium dioxide as described in claim 1, characterized in that, In step S1, the sand is milled until the average particle size is 0.32~0.35μm; The vibrating screen has a mesh size of 300-500 mesh.
5. The method for preparing highly dispersed titanium dioxide as described in claim 1, characterized in that, The inorganic coating in step S2 is a single aluminum coating, or a composite coating of aluminum and one or more selected from silicon, zirconium, cerium, titanium and phosphorus.
6. The method for preparing highly dispersed titanium dioxide as described in claim 1, characterized in that, The hydroxyl-containing polyacid in step S3 is selected from at least one of malic acid, citric acid, and tartaric acid.
7. The method for preparing highly dispersed titanium dioxide as described in claim 1, characterized in that, The amount of the hydroxyl-containing polyacid added is 0.1~0.5% of the mass of the titanium dioxide base material.
8. The method for preparing highly dispersed titanium dioxide as described in claim 1, characterized in that, Step S4: Grind the sand until the average particle size is less than 0.60 μm.
9. The method for preparing highly dispersed titanium dioxide as described in claim 1, characterized in that, The microwave heating temperature in step S5 is 70~90℃, the power is 100~300w, and the processing time for each step is 20~40min.
10. The method for preparing highly dispersed titanium dioxide as described in claim 1, characterized in that, The polyol compound is selected from at least one of TMP, TME, pentaerythritol, neopentyl glycol, sorbitol and hexaglycerol.
11. The method for preparing highly dispersed titanium dioxide as described in claim 1, characterized in that, In step S5, the total amount of the first organic treatment agent added is 0.05~0.3% of the mass of the titanium dioxide base material; In step S6, the amount of the second organic treatment agent added is 0.05~0.3% of the mass of the titanium dioxide base material.