High-brightness white anatase titanium dioxide pigment and preparation method thereof
By optimizing hydrolysis conditions and using specific reducing agents and surface modifiers, the method enhances the whiteness and dispersibility of anatase titanium dioxide, addressing compatibility issues and reducing yellowing in plastic products.
Patent Information
- Application Number
- CN202411183466.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-27
- Publication Date
- 2024-12-06
AI Technical Summary
Existing anatase titanium dioxide products suffer from poor whiteness stability, tinting strength, and compatibility issues, leading to yellowing of plastic products and increased production costs in recycled plastic applications.
A method involving controlled hydrolysis conditions, use of anatase seed crystals, specific reducing agents, and surface modification with modifiers and metal salts to enhance purity and dispersibility, followed by air flow pulverization to produce high-brightness anatase titanium dioxide.
The method results in titanium dioxide with improved whiteness stability, tinting strength, and compatibility, reducing yellowing and maintaining high whiteness in plastic products, with enhanced dispersibility and processing flowability.
Smart Images
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of titanium dioxide preparation, and more specifically, to a high-brightness white anatase titanium dioxide pigment and a preparation method thereof. Background Art
[0002] Titanium dioxide is a white pigment with good performance and is also an important chemical raw material. Due to its excellent optical properties, stable chemical properties, high refractive index and good hiding power, it is widely used in coatings, plastics, papermaking, inks and other fields.
[0003] With the rapid development of the plastic resin and recycled plastic industries (recycled plastics are currently widely used in textiles, automobiles, packaging, consumer electronics, etc.), if titanium dioxide has poor hue, whiteness, system compatibility, and temperature yellowing resistance, it will lead to yellowing of plastic products, increased addition, and increased production costs during the separation and reuse of recycled plastics. Titanium dioxide is mainly divided into anatase type and rutile type. The rutile type has better weather resistance and is not easy to yellow, while the anatase type has a higher whiteness and is more suitable for plastic products. Therefore, there is an increasing demand for anatase titanium dioxide products with high purity, blue phase, high whiteness, and easy dispersion.
[0004] In the current production process of anatase titanium dioxide, efficient reducing agents are added during the washing and crystallization process, and the washing levels are increased to reduce the total iron impurity content of the semi-finished product, resulting in the product's whiteness stability and tinting strength failing to meet requirements. Summary of the invention
[0005] In order to improve the whiteness stability and tinting strength of anatase titanium dioxide, the present application provides a high-brightness white anatase titanium dioxide pigment and a preparation method thereof.
[0006] In a first aspect, the present application provides a method for preparing a high-brightness white anatase titanium dioxide pigment, which mainly comprises the following steps: S1. Add titanyl sulfate to water at 60-65°C, heat to 95-97°C at a rate of 2.3-3.5°C / min for hydrolysis, adjust the pH of the system to 2.2-2.4 during the hydrolysis process, add anatase seed crystals to make the mass concentration of the seed crystals in the system 0.55-0.65%, filter and remove the filtrate after the hydrolysis reaction is completed to obtain titanium metaoxide; S2, adding titanium metabisulfite to water for pulping and dispersion, adding a reducing agent during the pulping process to make the mass concentration of the reducing agent in the slurry be 0.18-0.20%, and the reducing agent is one of aluminum powder, trivalent titanium, and organic reducing agent S-200; Then it is washed with sulfuric acid and dried to obtain a crude product; S3, blending the crude product and the modifier, grinding and sieving to obtain a modified crude product; S4, blending the modified crude product with the metal salt, and performing air flow pulverization to obtain.
[0007] By adopting the above technical solutions: First, through the titanium liquid hydrolysis process and parameters that affect the characteristics of metatitanic acid particles, we explored, tested and improved them, including hydrolysis temperature, heating rate, crystal seeds, etc., taking into account the blue phase and color-reducing power of titanium dioxide. Second, by further optimizing the washing and crystallization process of metatitanic acid, and optimizing the selection of reducing agents, we can make the impurity content in metatitanic acid low, the purity high, and the whiteness better, reduce the impurity Fe content, increase the purity of titanium dioxide to 98.5-98.7%, and make the brightness of titanium dioxide dry powder reach 98.85-98.91%.
[0008] In summary, the prepared anatase titanium dioxide product has higher brightness, whiteness stability, tinting strength, compatibility, dispersibility and processing flowability in the resin system than commercially available products.
[0009] Optionally, the titanyl sulfate is titanyl sulfate produced in a sulfuric acid process and subjected to sedimentation separation and fine filtration, and its iron content is expressed as Fe 2 O 3 The mass was calculated to be 40 ppm.
[0010] By adopting the above technical solution: This process can further effectively reduce the higher impurity iron content in titanyl sulfate, providing a better whiteness foundation for subsequent hydrolysis.
[0011] Optionally, the heating rate is 3.5°C / min and the hydrolysis temperature is 95°C.
[0012] By adopting the above technical solution: when the hydrolysis conditions are within the above range, the whiteness stability and tinting strength of the product are better.
[0013] Optionally, the titanium metaoxide, TiO 2 The concentration is 41-43%.
[0014] By adopting the above technical solution: when TiO 2 When the titanium metabisulfite with a concentration within the above range is subjected to subsequent steps, the whiteness stability and tinting strength of the prepared product are better.
[0015] Optionally, the modifier is one of stearate, phosphate, polyol and amine salt.
[0016] By adopting the above technical solution: using the above substances to modify the surface of the crude product, improving the dispersibility of the product, preventing secondary agglomeration of particles, and improving the compatibility, brightness, dispersibility and processing flowability of the product in the plastic system, finally obtaining a high-brightness, white and easily dispersible anatase titanium dioxide product that meets the requirements for application in plastic resins.
[0017] Optionally, the amount of the modifier added is 2 0.25-0.45% of mass.
[0018] By adopting the above technical solution: when the dosage of the modifier is within the above range, the prepared product has the best compatibility, brightness, dispersibility and processing fluidity in the plastic system.
[0019] Optionally, the metal salt is one of zinc oxide, kaolin, silica powder and barium sulfate.
[0020] By adopting the above technical scheme: after the metal salt and the modified crude product are jointly air flow-milled, the brightness of the product in the plastic product is improved, and the brightness and hue of the coloring pigment can be retained, and the heat resistance, wear resistance, drug resistance and water resistance of the plastic product can be improved.
[0021] Optionally, the amount of the metal salt added is: 2 3.5-4.5% of mass.
[0022] By adopting the above technical solution: when the added amount of the metal salt is within the above range, the performance of the prepared product is optimal.
[0023] In a second aspect, the present application provides an anatase titanium dioxide pigment, which is prepared by the above-mentioned high-brightness white anatase titanium dioxide pigment preparation method.
[0024] By adopting the above technical scheme: the rutile titanium dioxide prepared by the above preparation method has a dry powder whiteness of more than 98.48%, which is higher than that of commercially available products, and after being added to the plastic system, the yellowing is reduced, and the whiteness of the plastic products can be maintained at more than 94.25%, which is much higher than the whiteness of plastic products containing commercially available products of 89.92%, indicating that it is more suitable for plastic resin systems, and compared with commercially available products, it has higher brightness, whiteness stability, tinting strength, and compatibility, dispersibility and processing flowability in the resin system.
[0025] Optionally, the TiO 2 The content is 98.5-98.7wt%, the impurity Fe content is 13-20ppm, and the dry powder brightness is 98.85-98.91%.
[0026] In summary, this application has the following beneficial effects: 1. This application limits the temperature, heating rate, crystal seeds and other conditions in the hydrolysis process, takes into account the blue phase and decolorizing power that titanium dioxide should have, optimizes the titanium metabisulfite washing crystallization process and reducing agent, reduces the impurity iron content and improves the purity, so that titanium dioxide has higher whiteness stability and tinting power than commercially available products, and can be better used in plastic products; 2. In this application, TiO 2 The titanium metaoxide with a concentration within the above range is used in the subsequent steps, and the whiteness stability and tinting strength of the prepared product are better; 3. After the crude anatase titanium dioxide is obtained in this application, it is ground and surface-modified with substances such as stearate, and then the application performance is improved with ultrafine precipitated barium sulfate, and further crushed and particle size integrated in an air flow machine to improve the brightness and dispersibility of the product, prevent secondary agglomeration of particles, and improve the compatibility, brightness, dispersibility and processing flowability of the product in the plastic system; because the brightness of the product in the plastic product is improved, and the brightness and hue of the coloring pigment can be retained, the heat resistance, wear resistance, corrosion resistance and water resistance of the plastic product can also be improved. DETAILED DESCRIPTION
[0027] The present application is further described in detail below with reference to the embodiments.
[0028] Titanyl sulfate: Titanyl sulfate is produced in the sulfuric acid process and is separated by sedimentation and finely filtered. Performance parameters: total titanium concentration, in terms of TiO 2 200g / L; impurity Fe content (as Fe 2 O 3 40ppm; Anatase seed crystals: Add 95 kg of titanyl sulfate to 75 kg of water at 65 °C, and heat to 95 °C at a heating rate of 3.5 °C / min for hydrolysis reaction for 3.5 hours. During the hydrolysis process, add 20 wt% ammonia water to adjust the pH value of the system to 2.4, and keep the temperature for 5 minutes to obtain anatase seed crystals.
[0029] Example 1 Anatase titanium dioxide is prepared by the following steps: S1. Add 95 kg of titanyl sulfate to 75 kg of water at 65 ° C., heat to 95 ° C at a heating rate of 3.5 ° C / min, and perform hydrolysis reaction for 3.5 hours. Perform vacuum crystallization under the condition of vacuum degree of 0.0098 MPa, continue to add anatase type seed crystals to make the mass concentration of the seed crystals in the system 0.65%. After the hydrolysis reaction is completed, filter and remove the filtrate to obtain TiO 2 Titanium metabisulfite with a concentration of 42%; S2, add titanium metabisulfite to 95kg water for 3 times of pulping and washing, control the pulp temperature at 35°C during each pulping and washing process, and wash for 95min. Add reducing agent Ti during the pulping and washing process 2 (SO 4 ) 3 , make the mass concentration of reducing agent in the slurry system 0.18%, then flush into the sodium hydroxide aqueous solution with a concentration of 90g / L, keep the temperature during neutralization at 25-45℃, The acidity coefficient at the end point was controlled to be 0.45, and then the temperature was raised to 90°C at a rate of 2°C / min with stirring; After beating, add sulfuric acid (concentration of 175 g / L) 3 times the volume of the slurry for acid leaching, filter out the filtrate, and dry at 120 ° C for 1.5 h to obtain TiO 2 The content is 98.6%, the impurity iron content (Fe 2 O 3 The crude product is 14 ppm; S3, add the crude product to the Raymond mill, as well as TiO 2 0.35% by mass of calcium stearate, grinding and sieving to obtain a modified crude product with a particle size range of 0.21-0.45 μm; S4, add the modified crude product to the steam pulverizer, and the TiO 2 Ultrafine precipitated barium sulfate (particle size 6000 mesh) with a mass content of 3.5% is air flow-pulverized to produce anatase titanium dioxide with a particle size range of 0.15-0.35 μm.
[0030] Example 2 Anatase titanium dioxide is prepared by the following steps: S1. Add 105 kg of titanyl sulfate to 85 kg of water at 60 ° C., and heat to 96 ° C at a heating rate of 2.4 ° C / min for hydrolysis reaction for 3.5 hours. During the hydrolysis process, use 19 wt% ammonia water to adjust the pH value of the system to 2.3, and then continue to add anatase type seed crystals to make the mass concentration of the seed crystals in the system 0.55%. After the hydrolysis reaction is completed, filter and remove the filtrate to obtain TiO 2 Titanium metabisulfite with a concentration of 43%; S2, add titanium metabisulfite to 105kg water for 3 times of beating and washing, control the slurry temperature at 36°C during each beating and washing process, and the water washing time is 100min. Add reducing agent aluminum oxide during the beating and washing process to make the mass concentration of the reducing agent in the slurry system 0.20%, and then flush into a sodium hydroxide aqueous solution with a concentration of 90g / L, keep the temperature during neutralization at 25-45°C, control the acidity coefficient at the end point to be 0.45, and then heat to 90°C at a rate of 2°C / min and stir; After beating, add sulfuric acid (concentration of 175 g / L) 3 times the volume of the slurry for acid leaching, filter out the filtrate, and dry at 120 ° C for 1.5 h to obtain TiO 2 The content is 98.5%, the impurity iron content (Fe 2 O 3 The crude product is 15 ppm; S3, add the crude product to the Raymond mill, as well as TiO 2 0.25% by mass of ammonium chloride, grinding and sieving to obtain a modified crude product with a particle size range of 0.21-0.45 μm; S4, add the modified crude product to the steam pulverizer, and the TiO 2 4% by mass of zinc oxide (particle size 3000 mesh) is air flow-pulverized to produce anatase titanium dioxide with a particle size range of 0.15-0.35 μm.
[0031] Example 3 Anatase titanium dioxide is prepared by the following steps: S1. Add 100 kg of titanyl sulfate to 80 kg of water at 65 ° C. and heat to 97 ° C at a heating rate of 2.3 ° C / min for hydrolysis reaction for 3.4 hours. During the hydrolysis process, use 19 wt% ammonia water to adjust the pH value of the system to 2.2, and then continue to add anatase type seed crystals to make the mass concentration of the seed crystals in the system 0.60%. After the hydrolysis reaction is completed, filter and remove the filtrate to obtain TiO 2 Titanium metabisulfite with a concentration of 43%; S2. Add titanium metabisulfite to 100 kg of water and perform pulping and washing for 3 times. During each pulping and washing process, the pulp temperature is controlled at 36° C. The washing time is 100 min. During the pulping and washing process, an organic reducing agent S-200 is added to make the mass concentration of the reducing agent in the pulp system 0.19%. Then, the pulp is poured into a sodium hydroxide aqueous solution with a concentration of 90 g / L. The temperature during neutralization is maintained at 25-45° C. The acidity coefficient at the end point is controlled to be 0.45. Then, the temperature is raised to 90° C. at a rate of 2° C. / min and stirred. After beating, add sulfuric acid (concentration of 175 g / L) 3 times the volume of the slurry for acid leaching, filter out the filtrate, and dry at 120 ° C for 1.5 h to obtain TiO 2 The content is 98.7%, the impurity iron content (Fe 2 O 3 20 ppm crude product; S3, add the crude product to the Raymond mill, as well as TiO 2 0.45% calcium stearate by weight is ground, modified and sieved to obtain a modified crude product with a particle size range of 0.21-0.40 μm; S4, add the modified crude product to the steam pulverizer, and the TiO 2 Ultrafine precipitated barium sulfate (6000 mesh in particle size) with a mass content of 4.5% is subjected to air flow milling to obtain anatase titanium dioxide with a particle size range of 0.15-0.35 μm.
[0032] Comparative Example 1 Anatase titanium dioxide, model JMA110, manufactured by Guangxi Jinmao Titanium Industry Co., Ltd.
[0033] Comparative Example 2 A type of anatase titanium dioxide, model SFA101, produced by Guangxi Shunfeng Titanium Industry Co., Ltd.
[0034] Comparative Example 3 An anatase titanium dioxide, which is different from Example 1 in that steps S1 and S2 are different, as follows: S1. Add 95 kg of titanium oxysulfate to 75 kg of water at 65 ° C., and heat to 110 ° C. at a heating rate of 10 ° C. / min for a hydrolysis reaction for 3.5 hours. During the hydrolysis process, adjust the pH value of the system to 2.4 with 20 wt% ammonia water, and continue to add anatase type seed crystals to make the mass concentration of the seed crystals in the system 0.5%. After the hydrolysis reaction is completed, filter and remove the filtrate to obtain titanium metaacid; S2, add titanium metabisulfite to 95kg water for 3 times of beating and washing, control the slurry temperature at 35°C during each beating and washing process, and the water washing time is 95min. Add trivalent titanium as a reducing agent during the beating and washing process to make the mass concentration of the reducing agent in the slurry system 0.18%, and then flush into a sodium hydroxide aqueous solution with a concentration of 90g / L, maintain the temperature during neutralization at 25-45°C, control the acidity coefficient at the end point to be 0.45, and then heat to 90°C at a rate of 2°C / min and stir; After the beating is completed, the filtrate is removed by filtration and dried at 120° C. for 1.5 h to obtain a crude product.
[0035] Comparative Example 4 An anatase titanium dioxide pigment is different from Example 1 in that steps S3 and S4 are not performed.
[0036] Performance Testing The titanium dioxide pigments prepared in the examples and comparative examples were subjected to the following performance tests, and the test results are recorded in Table 1.
[0037] Detection Methods 1. After the titanium dioxide powder is pressed into a cake using a manual cake press, it is tested using a CM-23d spectrophotometer to obtain the L value, b value and whiteness.
[0038] 2. Add 4 g of titanium dioxide and 196 g of PP numerically blended to a HTW-500x2 horizontal injection molding machine to obtain a sample with a thickness of 2 mm. The sample is tested using a CM-23d spectrophotometer to obtain the L value, b value and whiteness.
[0039] 3. Filter Pressure Value (FPV) is measured by using a twin-screw extruder to mix the sample with linear low-density polyethylene (LLDPE) to make a 70% concentration masterbatch, adding natural resin to dilute it into a carrier mixture containing 14% titanium dioxide, and then testing it with a single-screw extruder. It is used to characterize the dispersibility of titanium dioxide. A smaller value indicates better dispersibility in the system.
[0040] 4. Melt index (MFR) is obtained by mixing titanium dioxide with linear low-density polyethylene (LLDPE) with an MFR of 25g / 10min using a twin-screw extruder to make a 60% concentration masterbatch, and then testing the melt mass flow rate (MFR) according to ISO1133-1:2011 standard. The test parameters are set (temperature is 190°C, load is 2.16kg) to characterize the compatibility and flowability of titanium dioxide in the resin system. A large value indicates good compatibility and flowability in the system.
[0041] Table 1 Performance test results Referring to Table 1, the whiteness of the titanium dioxide dry powder obtained in Examples 1-3 is above 98.48%, and the whiteness after blending with PP resin and making plates is maintained at above 94.41%; while the whiteness of the dry powder of the commercially available product is significantly lower than that of the product of the present application, especially the whiteness after being added to the resin system is lower, about 90%, indicating that it has a larger yellowing, indicating that the titanium dioxide prepared in the present application has a higher whiteness, less yellowing, better stability and better tinting power in the application resin system; at the same time, after comparative testing, the filter pressure value is smaller and the melt index is larger, indicating that the patented product has better dispersibility in the plastic system and better compatibility and fluidity in the system, and better meets the characteristics of plastic resins for rutile titanium dioxide pigments.
[0042] The difference between Comparative Example 3 and Example 1 is that the processing parameters in steps S1 and S2 are different, and the whiteness of titanium dioxide decreases.
[0043] The difference between Comparative Example 4 and Example 1 is that without performing steps S3 and S4, the application performance index of titanium dioxide decreases.
[0044] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.
Claims
1. A high-brightness white anatase titanium dioxide pigment and a preparation method thereof, characterized in that: The following steps are involved: S1. Add titanium oxysulfate to water at 60-65°C, heat to 95-97°C at a rate of 2.3-3.5°C / min for hydrolysis, adjust the pH of the system to 2.2-2.4 during the hydrolysis process, then add anatase seed crystals to make the mass concentration of the seed crystals in the system 0.55-0.65%, filter and remove the filtrate after the hydrolysis reaction is completed to obtain titanium metaoxide; S2, adding titanium metabisulfite to water for pulping and dispersion, adding a reducing agent during the pulping process to make the mass concentration of the reducing agent in the slurry be 0.18-0.20%, and the reducing agent is one of aluminum powder, trivalent titanium, and organic reducing agent S-200; Then it is washed with sulfuric acid and dried to obtain a crude product; S3, blending the crude product and the modifier, grinding and sieving to obtain a modified crude product; S4, grinding the modified crude product and the metal salt by air flow to obtain.
2. The method for preparing high-brightness white anatase titanium dioxide according to claim 1, characterized in that: The heating rate is 3.5°C / min, and the hydrolysis temperature is 95°C.
3. The method for preparing a high-brightness white anatase titanium dioxide pigment according to claim 1, characterized in that: The titanium metabisulfite has a TiO2 concentration of 41-43%.
4. The method for preparing a high-brightness white anatase titanium dioxide pigment according to claim 1, characterized in that: The titanyl sulfate is titanyl sulfate produced in a sulfuric acid production process and subjected to sedimentation separation and fine filtration, and the impurity iron content thereof is 40 ppm in terms of Fe2O3 mass.
5. The method for preparing high-brightness white anatase titanium dioxide according to claim 1, characterized in that: The modifier is one of stearate, phosphate, polyol and amine salt.
6. The method for preparing high-brightness white anatase titanium dioxide according to claim 5, characterized in that: The amount of the modifier added is 0.25-0.45% of the mass of TiO2 in the crude product.
7. The method for preparing a high-brightness white anatase titanium dioxide pigment according to claim 1, characterized in that: The metal salt is one of zinc oxide, kaolin, silicon powder and barium sulfate.
8. The method for preparing a high-brightness white anatase titanium dioxide pigment according to claim 7, characterized in that: The amount of the metal salt added is 3.5-4.5% of the mass of TiO2 in the modified crude product.
9. Anatase titanium dioxide, characterized in that: The high-brightness white anatase titanium dioxide pigment is prepared by the preparation method of any one of claims 1 to 8.
10. Anatase titanium dioxide according to claim 9, characterized in that: The TiO2 content is 98.5-98.7wt%, the impurity Fe content is 13-20ppm based on the mass of Fe2O3, and the dry powder brightness is 98.85-98.91%.