Composite titanium dioxide with low dust raising property and preparation method thereof

Abstract

The application discloses a kind of composite titanium dioxide with low dust raising characteristics and preparation method thereof, belong to titanium dioxide production technical field.It is composed of the following raw materials: rutile titanium dioxide raw powder, inorganic additive, organic modifier, the prepared composite titanium dioxide has stable micron aggregate, Ti-OH group on the surface of titanium dioxide raw powder and inorganic metal ion form firm Ti-O-M chemical bond framework structure, organic additive forms flexible network by hydrogen bond and van der waals force, both anchor and connect titanium dioxide raw powder and form stable aggregate, the structure increases the size of agglomerate, reduces specific surface area, suppresses dust flying from physical level;At the same time, the aggregate can effectively depolymerize in application medium, restore the high dispersibility of primary particle, realize the unity of dry powder dust suppression and application performance, overcome the technical contradiction of traditional scheme "dust suppression and dispersion are difficult to consider".

Description

Technical Field

[0001] This invention belongs to the field of titanium dioxide production technology, specifically relating to a composite titanium dioxide with low dust emission and its preparation method. Background Technology

[0002] Titanium dioxide (TiO2) is widely used as a white pigment in industries such as coatings, plastics, inks, and papermaking due to its excellent whiteness, hiding power, and chemical stability. However, commercially available titanium dioxide is typically composed of nano- or submicron-sized primary particles with a large specific surface area and high surface energy. During transportation, storage, and dry powder feeding, these loosely packed particles are easily dispersed by airflow or mechanical vibration, resulting in severe dust generation. This not only wastes materials and increases cleaning costs but also pollutes the production environment and seriously threatens the respiratory health of operators.

[0003] To improve the performance of titanium dioxide, existing technologies mostly employ inorganic materials (such as alumina and silica), organic materials, or organic-inorganic combinations for surface treatment. The main purpose is to improve its dispersibility in application media (such as coatings and plastics). For example, Chinese patent publication number CN105062150A, "A Treatment Method for Improving the Weather Resistance of Titanium Dioxide," discloses improving the weather resistance and dispersibility of titanium dioxide by coating it with silica. Chinese patent publication number CN121108779A, "A High-Opacity Inorganic-Organic Coated Titanium Dioxide and Its Preparation Method and Application," discloses using a coating method to improve the dispersibility and opacity of titanium dioxide.

[0004] However, these technical solutions typically prioritize the "high dispersibility" of the particles. For dry powder, high dispersibility means weak interparticle interactions and independence, which can actually exacerbate dust problems. For example, Chinese patent CN101684280A, "A Composite Modified Titanium Dioxide and Its Preparation Method," discloses a composition consisting of a titanium dioxide core, an inorganic film layer coated on the core, and an organic film layer coated on top of the inorganic film layer. The inorganic film layer has at least two layers: one layer near the core layer contains at least one of silicon dioxide and aluminum oxide, and the other layer away from the core layer contains zirconium dioxide. The organic film layer is obtained by reacting titanium dioxide with the inorganic film layer on its surface with an organic coating liquid. While the disclosed composite modified titanium dioxide improves the weather resistance and dispersibility of titanium dioxide, it lacks limitations on titanium dioxide dust generation.

[0005] Chinese invention patent CN114958034A, entitled "A Preparation Method of Organic Composite Coating of Titanium Dioxide for Plastics," discloses a method for preparing organic composite coating of titanium dioxide for plastics. The method involves feeding a qualified filter cake into a flash evaporation feeding hopper while simultaneously adding a polyol-based additive A. After flash evaporation, the filter cake is fed into a steam-pulverized mill, where a silane coupling agent-based additive B is added. The filter cake is then pulverized by the steam-pulverized mill and subsequently passed through a cyclone dust collector and a high-temperature bag filter. The resulting titanium dioxide is slowly cooled to room temperature before packaging. This method reduces dust generation and enhances the coating effect of titanium dioxide, but the preparation process is cumbersome. Currently, there are few technical solutions specifically designed to suppress dust generation from dry titanium dioxide powder. Some solutions attempt to add liquid dust suppressants or perform large-particle granulation, but this introduces additional impurities, damaging the original properties of the product or causing dispersion difficulties in downstream applications. Modifying titanium dioxide using a single force (such as physical adsorption or weak hydrogen bonding) may result in weak bonding between the coating layer and the particles, making it prone to detachment under external forces such as transportation and stirring, leading to poor dust suppression. Therefore, how to significantly reduce the dust-generating characteristics of titanium dioxide in its dry powder state while maintaining its original application performance (such as dispersibility and hiding power) is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention discloses a composite titanium dioxide with low dust emission characteristics and its preparation method. The composite titanium dioxide is prepared by mixing rutile titanium dioxide raw powder, inorganic additives, and organic modifiers. The prepared titanium dioxide is a micron-sized aggregate with a "grape bunch" structure, which can resist external damage and easily deagglomerate during application, achieving a balance between dust suppression performance and application performance.

[0007] To achieve the purpose of the invention, the following technical solution is provided: This invention discloses a composite titanium dioxide with low dust emission characteristics. The titanium dioxide is a micron-sized aggregate and includes the following raw materials: rutile titanium dioxide raw powder, inorganic additives, and organic modifiers.

[0008] Furthermore, the composite titanium dioxide is constructed by forming Ti-OM chemical bonds between Ti-OH groups on the surface of the titanium dioxide raw powder and metal ions in the inorganic additives to build a framework structure, and the organic long chains in the organic modifier form a flexible network structure between the titanium dioxide raw powders.

[0009] Furthermore, the composite titanium dioxide comprises the following raw materials in parts by weight: 80-99 parts of rutile titanium dioxide raw powder, 0.5-15 parts of inorganic additives, and 0.1-10 parts of organic modifiers.

[0010] Furthermore, the ratio of organic to inorganic additive components is (1-4):(6-9), forming aggregates with a size of 2-30 μm.

[0011] Furthermore, the inorganic additives are magnesium salts and aluminum salts.

[0012] Furthermore, the magnesium salt is one or more of magnesium chloride, magnesium sulfate, or magnesium nitrate; the aluminum salt is one or more of aluminum chloride, aluminum sulfate, or sodium aluminate.

[0013] Furthermore, the organic modifier is a polymer or silane coupling agent containing hydroxyl, amide, amino, or epoxy groups.

[0014] Further, the polymer is one or more of polyvinylpyrrolidone, polyethylene glycol, or polyvinyl alcohol; the silane coupling agent is one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-methacryloyloxypropyltrimethoxysilane.

[0015] This invention also discloses a method for preparing composite titanium dioxide with low dust emission characteristics, comprising the following steps: S1. Disperse titanium dioxide raw powder in deionized water and stir to form a slurry with a solid content of 15-50%; S2. Dissolve the inorganic additives and organic modifiers in deionized water to prepare a mixed additive solution with a total mass concentration of 5-30%. S3. Under stirring conditions, the mixed additive solution prepared in S2 is slowly added dropwise to the slurry prepared in S1, while adjusting the pH of the system to 7.5-9.5 with an alkaline solution. S4. Heat the reaction slurry to 60-95℃ and stir to react at a constant temperature. S5. After the reaction is complete, age the slurry, then centrifuge or filter press and wash until the conductivity of the filtrate is less than 200 μS / cm. S6. The washed filter cake is dried, and the dried material is deagglomerated by low-temperature airflow pulverization or mechanical dispersion to obtain the composite titanium dioxide; the temperature of the low-temperature airflow pulverization medium is below 60°C.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention discloses a composite titanium dioxide with low dust generation characteristics, which is prepared by mixing rutile titanium dioxide raw powder, inorganic additives and organic modifiers. The organic-inorganic additives connect a large amount of titanium dioxide raw powder and agglomerate it into stable aggregates with a size in the micrometer range (with the primary titanium dioxide particles as "grapes" and the additives as "stalks" or "binders"). The prepared titanium dioxide has a "grape bunch" microstructure. This "grape bunch" structure fundamentally reduces the specific surface area and surface energy of the product, making the titanium dioxide less prone to breakage and dusting under external force, thus effectively reducing the dust generation of titanium dioxide.

[0017] 2. This invention discloses a composite titanium dioxide with low dust emission characteristics. The additives and titanium dioxide raw powder used are not simply physically mixed, but are tightly bound to the titanium dioxide raw powder through multi-level intermolecular forces, i.e., a synergistic structure of "chemical anchoring-physical agglomeration". First, the metal ions in the additives chemically bond with the Ti-OH matrix on the surface of the titanium dioxide raw powder, forming strong Ti-OM chemical bonds, providing a stable structural framework. Second, the long organic chains in the organic modifier interweave into a network between the titanium dioxide raw powder particles, forming a flexible entangled network structure through dense hydrogen bonds and van der Waals forces, achieving a "rigid-flexible" anchoring of the titanium dioxide raw powder. This combination of forces allows the prepared titanium dioxide with a "grape bunch" structure to resist external damage and smoothly deagglomerate during application, achieving a unity of dust suppression performance and application performance. This overcomes the technical contradiction of "difficulty in simultaneously achieving dust suppression and dispersion" in traditional solutions.

[0018] 3. The composite titanium dioxide with low dust emission characteristics disclosed in this invention can reduce dust emission by up to 88% or more compared with untreated titanium dioxide. Furthermore, by adjusting the ratio of inorganic to organic components in the additives, the agglomeration size and bonding strength of the product can be flexibly changed. A lower organic / inorganic component ratio forms smaller, more rigid aggregates dominated by chemical bonds, suitable for coating systems requiring high shear force dispersion. A higher organic / inorganic component ratio forms larger, more flexible aggregates dominated by hydrogen bonds and van der Waals forces, suitable for plastics and ink systems requiring low shear force dispersion. The composite titanium dioxide disclosed in this invention has high customizability, meeting the differentiated needs of various downstream fields such as coatings, plastics, and inks for dispersion speed and shear sensitivity, and has good industrial adaptability and promising prospects for widespread application. Attached Figure Description

[0019] Figure 1 These are dust control effect diagrams of Embodiment 1 and Comparative Example 1 of the present invention; Figure 2 This is EDS-Mapping for Embodiment 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, all raw materials used in the following examples were purchased commercially.

[0022] Unless otherwise specified, the methods used in the following embodiments are conventional operating methods in the art.

[0023] The dust emission performance test method in the embodiments of this invention is as follows: A self-made dust settling test device is used. A 50g sample is weighed and placed in a funnel 0.5 meters above the receiving tray. The flow rate is controlled so that it falls freely within 30 seconds. The dust that settles within a 1-meter radius around the receiving tray is collected and weighed as m1. The dust that escapes outside the device (collected through a filter membrane) is collected and weighed as m2. Dust emission rate = m2 / (m1+m2)×100%.

[0024] Aggregate size test: The samples were observed using a scanning electron microscope (SEM), and at least 100 aggregates were randomly selected to measure their maximum dimensional dimensions and their distribution range was statistically analyzed.

[0025] Dispersion performance test (application performance characterization): The sample from the examples or comparative examples was added to the waterborne acrylic coating system at a mass ratio of 20%, dispersed at 2000 rpm for 15 minutes using a high-speed disperser, coated onto a film, and the fineness was measured using a fineness tester. The fineness was compared with that of unmodified titanium dioxide with the same solid content (Comparative Example 1). For general industrial coating applications, a fineness ≤35 μm is generally considered to meet the dispersion requirements.

[0026] Example 1 This embodiment provides a composite titanium dioxide with low dust emission characteristics, comprising the following raw materials in parts by weight: 90 parts rutile titanium dioxide raw powder, 5 parts magnesium chloride, 3 parts aluminum sulfate, and 2 parts polyvinylpyrrolidone.

[0027] The preparation method of the composite titanium dioxide with low dust generation characteristics in this embodiment is as follows: S1. Disperse rutile titanium dioxide raw powder in deionized water and stir to form a slurry with a solid content of 30%. S2. Dissolve magnesium chloride, aluminum sulfate and polyvinylpyrrolidone in deionized water to prepare a mixed additive solution; S3. Under the condition of 800-3000 rpm, the mixed additive solution obtained in S2 is slowly added dropwise to the slurry obtained in S1, and at the same time the pH value of the system is adjusted to 8.5 with alkaline solution. S4. Heat the reaction slurry prepared in S3 to 75°C and stir at a constant temperature for 2 hours. S5. Let the slurry age for 2 hours, then centrifuge and wash until the conductivity of the filtrate is less than 200 μS / cm. S6. The washed filter cake is dried at 105°C for 12 hours, and then subjected to air jet pulverization at 60°C to obtain the composite titanium dioxide.

[0028] The composite titanium dioxide prepared in this embodiment, as observed by scanning electron microscopy, shows that the titanium dioxide particles agglomerate to form a "grape bunch" aggregate structure with an aggregate size of 2-10 μm and a dust emission of 18% (relative value).

[0029] Example 2 This embodiment provides a composite titanium dioxide with low dust emission characteristics, comprising the following raw materials in parts by weight: 90 parts rutile titanium dioxide raw powder, 6 parts magnesium chloride, 2 parts aluminum sulfate, and 2 parts γ-aminopropyltriethoxysilane.

[0030] The preparation method of the composite titanium dioxide with low dust generation characteristics in this embodiment is as follows: S1. Disperse rutile titanium dioxide raw powder in deionized water and stir to form a slurry with a solid content of 40%. S2. Dissolve magnesium chloride, aluminum sulfate and γ-aminopropyltriethoxysilane in deionized water to prepare a mixed auxiliary agent solution; S3. Under high-speed stirring conditions, the mixed additive solution obtained in S2 is slowly added dropwise to the slurry obtained in S1, and at the same time the pH value of the system is adjusted to 8.0 with an alkaline solution. S4. Heat the reaction slurry prepared in S3 to 75°C and stir at a constant temperature for 3 hours. S5. Let the slurry age for 2 hours, then centrifuge and wash until the conductivity of the filtrate is less than 200 μS / cm. S6. The washed filter cake is dried at 120°C for 10 hours, and then air-jet pulverized at 60°C to obtain the composite titanium dioxide.

[0031] The product obtained in this embodiment exhibits a "grape bunch" aggregate structure with an aggregate size of 5-25μm and a dust emission rate of 23% (relative value).

[0032] Example 3 This embodiment provides a composite titanium dioxide with low dust emission characteristics, which is composed of the following raw materials in parts by weight: 90 parts rutile titanium dioxide raw powder, 4 parts magnesium nitrate, 2 parts sodium aluminate, and 2 parts polyvinylpyrrolidone.

[0033] The preparation method of the composite titanium dioxide in this embodiment is as follows: S1. Disperse rutile titanium dioxide raw powder in deionized water and stir to form a slurry with a solid content of 40%. S2. Dissolve magnesium chloride, aluminum sulfate and polyvinylpyrrolidone in deionized water to prepare a mixed additive solution; S3. Under high-speed stirring conditions, the mixed additive solution obtained in S2 is slowly added dropwise to the slurry obtained in S1, and at the same time the pH value of the system is adjusted to 8.5 with an alkaline solution. S4. Heat the reaction slurry prepared in S3 to 80°C and stir at a constant temperature for 3 hours. S5. Let the slurry age for 2.5 hours, then centrifuge and wash until the conductivity of the filtrate is less than 200 μS / cm. S6. The washed filter cake is dried at 80°C for 20 hours, and then mechanically dispersed and depolymerized to obtain the composite titanium dioxide.

[0034] The aggregate size of the product obtained in this embodiment is 3-15μm, and the dust emission is 22% (relative value).

[0035] Example 4: This embodiment provides a composite titanium dioxide with low dust emission characteristics, which is composed of the following raw materials in parts by weight: 90 parts rutile titanium dioxide raw powder, 5 parts magnesium chloride, 3 parts aluminum sulfate, and 2 parts polyethylene glycol PEG-4000.

[0036] The preparation method of the composite titanium dioxide in this embodiment is the same as in Example 1.

[0037] The aggregate size of the product obtained in this embodiment is 2-18μm, and the dust emission is 25% (relative value).

[0038] Example 5: This embodiment provides a composite titanium dioxide with low dust emission characteristics, which is composed of the following raw materials in parts by weight: 90 parts rutile titanium dioxide raw powder, 6 parts magnesium chloride, 2 parts aluminum sulfate, and 2 parts γ-methacryloyloxypropyltrimethoxysilane.

[0039] The preparation method of the composite titanium dioxide in this embodiment is the same as in Embodiment 2.

[0040] The aggregate size of the product obtained in this embodiment is 5-20μm, and the dust emission is 28% (relative value).

[0041] Experiment on adjusting the inorganic / organic ratio: To illustrate the effect of the ratio of organic to inorganic additives on the performance regulation of the product, the following series of examples were designed: Examples 6-8 all used the same preparation method and raw materials as Example 1 (the inorganic additives were magnesium chloride and aluminum sulfate, with a weight ratio of 5:3; the organic modifier was polyvinylpyrrolidone), only changing the ratio of the total number of inorganic additives to the number of organic modifiers.

[0042] Example 6: Raw material composition: 90 parts titanium dioxide raw powder, 9 parts inorganic additives (magnesium chloride + aluminum sulfate), 1 part polyvinylpyrrolidone.

[0043] The preparation method of the composite titanium dioxide in this embodiment is the same as in Example 1.

[0044] The resulting product aggregates have a size of 1-3 μm and a dust emission rate of 35% (relative value).

[0045] Example 7: Raw material composition: 90 parts titanium dioxide raw powder, 8 parts inorganic additives (magnesium chloride + aluminum sulfate), 2 parts polyvinylpyrrolidone.

[0046] The preparation method of the composite titanium dioxide in this embodiment is the same as in Example 1.

[0047] The resulting product aggregates have a size of 2-10 μm and a dust emission of 18% (relative value).

[0048] Example 8: Raw material composition: 90 parts titanium dioxide raw powder, 6 parts inorganic additives (magnesium chloride + aluminum sulfate), 4 parts polyvinylpyrrolidone.

[0049] The preparation method of the composite titanium dioxide in this embodiment is the same as in Example 1.

[0050] The resulting product aggregates have a size of 8-30μm and a dust emission of 12% (relative value).

[0051] Results analysis: With the increase of the proportion of organic modifier, the aggregate size increased significantly and the dust suppression effect was further improved (dust amount decreased from 35% to 12%), proving that the aggregate size and dust suppression performance of the product can be flexibly controlled by adjusting the ratio of organic / inorganic components.

[0052] Comparative Example 1 This embodiment provides an unmodified titanium dioxide, which is composed of the following parts by weight of raw materials: 100 parts of rutile titanium dioxide raw powder; in this comparative example, the titanium dioxide raw powder has not added any inorganic or organic additives, nor has it undergone surface coating treatment.

[0053] The preparation method of the unmodified titanium dioxide in this embodiment is as follows: A1. Disperse titanium dioxide raw powder in deionized water and stir to form a slurry with a solid content of 30%; A2. Centrifuge and wash the obtained slurry until the conductivity of the filtrate is less than 200 μS / cm; A3. The washed filter cake is dried at 105°C for 12 hours, and then subjected to air jet pulverization at 60°C to obtain the unmodified titanium dioxide.

[0054] In this comparative example, the unmodified titanium dioxide, as observed by scanning electron microscopy, exhibited loosely distributed nano-sized particles with no obvious agglomeration structure between particles, and the aggregate size was <1μm. The dust emission was 100% (benchmark).

[0055] The performance and effects of the composite titanium dioxide prepared in Examples 1-8 and Comparative Example 1 are compared as follows: like Figure 1 As shown, the preferred embodiment 1 and the comparative embodiment 1 were tested under the dust performance testing method constructed in this application. The dust emission of embodiment 1 was significantly lower than that of comparative embodiment 1, indicating that the composite titanium dioxide disclosed in this invention has excellent dust suppression characteristics.

[0056] EDS-mapping images of the composite titanium dioxide prepared in Examples and Comparative Example 1 ( Figure 2 As can be observed in Example 1, agglomeration is observed, while in Comparative Example 1, the structure is loose and there is no obvious agglomeration.

[0057] The microstructure, aggregate size, dust emission, and dispersion fineness of the titanium dioxide prepared in the examples and comparative examples were compared, and the results are shown in Table 1: Table 1. Comparison of the effects of the examples and comparative examples.

[0058] As shown in Table 1, compared with Comparative Example 1, the dust emission of all embodiments of the present invention was reduced by more than 65% (65% in Example 6 and 88% in Example 8), demonstrating a significant dust suppression effect. Simultaneously, regarding the application dispersion fineness index, the increase in fineness for all embodiments was within an acceptable range (for general industrial coatings, a fineness ≤35μm is sufficient), indicating that its loose aggregate structure can effectively deagglomerate under the shear force of the application medium, without negatively impacting the application dispersion performance. The present invention successfully achieves a balance between the two seemingly contradictory performance characteristics of "dry powder dust suppression" and "application dispersion."

[0059] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A composite titanium dioxide with low dust emission characteristics, characterized in that: The titanium dioxide is a micron-sized aggregate, comprising the following raw materials: Rutile titanium dioxide raw powder, inorganic additives and organic modifiers.

2. The composite titanium dioxide with low dust emission characteristics as described in claim 1, characterized in that: The Ti-OH groups on the surface of rutile titanium dioxide raw powder and the metal ions in the inorganic additives form Ti-OM chemical bonds to construct a framework structure, and the organic long-chain rutile titanium dioxide raw powder in the organic modifier forms a flexible network structure.

3. The composite titanium dioxide with low dust generation characteristics as described in claim 1, characterized in that: The raw materials include the following parts by weight: 80-99 parts of rutile titanium dioxide raw powder, 0.5-15 parts of inorganic additives, and 0.1-10 parts of organic modifiers.

4. The composite titanium dioxide with low dust generation characteristics as described in claim 1, characterized in that: The ratio of organic modifier to inorganic additive is (1-4):(6-9), forming micron-sized aggregates of 2-30 μm.

5. The composite titanium dioxide with low dust generation characteristics as described in claim 1, characterized in that: The inorganic additives are magnesium salts and aluminum salts.

6. The composite titanium dioxide with low dust emission characteristics as described in claim 5, characterized in that: The magnesium salt is one or more of magnesium chloride, magnesium sulfate, or magnesium nitrate; the aluminum salt is one or more of aluminum chloride, aluminum sulfate, or sodium aluminate.

7. The composite titanium dioxide with low dust emission characteristics as described in claim 1, characterized in that: The organic modifier is a polymer or silane coupling agent containing hydroxyl, amide, amino, or epoxy groups.

8. The composite titanium dioxide with low dust emission characteristics as described in claim 7, characterized in that: The polymer is one or more of polyvinylpyrrolidone, polyethylene glycol, or polyvinyl alcohol; the silane coupling agent is one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-methacryloyloxypropyltrimethoxysilane.

9. A method for preparing composite titanium dioxide with low dust emission characteristics as described in claim 1, characterized in that: Includes the following steps: S1. Disperse titanium dioxide raw powder in deionized water and stir to form a slurry with a solid content of 15-50%; S2. Dissolve the inorganic additives and organic modifiers in deionized water to prepare a mixed additive solution with a total mass concentration of 5-30%. S3. Under stirring conditions, the mixed additive solution prepared in S2 is slowly added dropwise to the slurry prepared in S1, while adjusting the pH of the system to 7.5-9.5 with an alkaline solution. S4. Heat the reaction slurry to 60-95℃ and stir to react at a constant temperature. S5. After the reaction is complete, age the slurry, then centrifuge or filter press and wash until the conductivity of the filtrate is less than 200 μS / cm. S6. Dry the washed filter cake, and then deagglomerate the dried material by low-temperature airflow pulverization or mechanical dispersion to obtain the composite titanium dioxide; the temperature of the low-temperature airflow pulverization medium is below 60°C.

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