A titanium dioxide filler for polyester and its preparation method

Abstract

This invention belongs to the field of titanium dioxide manufacturing technology, specifically relating to a titanium dioxide filler for polyester and its preparation method. In this invention, titanium dioxide and weather-resistant additives work together, and cerium sulfate treatment is introduced. The ionic radius effect of cerium inhibits the anatase-to-rutile phase transition during calcination, improving the thermal stability of the anatase crystal form. Mesoporous silica loaded with calcium chloride is used to prepare dye-promoting silica. The silica surface has silanol groups, exhibiting weak acidity. Calcium chloride neutralizes some of the acidic sites, inhibiting the thermal oxidative degradation of polyester during high-temperature processing. A composite antioxidant inhibits the yellowing, embrittlement, and strength reduction of polyester fibers caused by thermal oxidative aging during long-term use. This avoids the problems of poor spinnability and uneven performance of polyester fibers caused by titanium dioxide agglomeration, ultimately obtaining high-quality polyester fibers with high initial whiteness, excellent matting effect, and excellent durability.

Description

Technical Field

[0001] This invention belongs to the field of titanium dioxide manufacturing technology, specifically relating to a titanium dioxide filler for polyester and its preparation method. Background Technology

[0002] Polyester, as the world's largest-produced synthetic fiber, is widely used in clothing, home textiles, and industrial textiles. However, virgin polyester suffers from drawbacks such as stiff luster and insufficient whiteness. Furthermore, in humid and hot environments, the antioxidant 2,6-di-tert-butyl-4-methylphenol easily transfers to the surface of white polyester fabrics through volatilization or friction, forming yellow substances with nitrogen-containing oxides under alkaline conditions, leading to yellowing of the fabric. Therefore, it is necessary to add titanium dioxide to modify polyester and improve its resistance to oxidation and yellowing. In recent years, chemical fiber-grade titanium dioxide has been developing towards high purity, narrow particle size distribution, and functional composites, especially in the high-end differentiated polyester field, where the requirements for dispersion stability and high-temperature yellowing resistance of titanium dioxide are continuously increasing. Currently, titanium dioxide has shortcomings in batch stability, high-temperature yellowing resistance, and dispersion filtration performance, which can easily lead to spinneret clogging and fiber embrittlement during spinning. Therefore, there is an urgent need to develop a polyester-specific titanium dioxide that can meet the requirements of high purity and high dispersibility.

[0003] Chinese invention patent CN117430973B discloses a modified titanium dioxide for matting polyester fibers and its preparation method. The modified titanium dioxide comprises a mesoporous titanium dioxide core and a cysteine ​​graft layer grafted into the pores of the mesoporous titanium dioxide. The mesoporous titanium dioxide core is prepared by evaporation-induced self-assembly using an alkenyl sulfonate surfactant as a liquid crystal template and tetraethyl or tetrabutyl titanate as the titanium source. Due to the self-polymerization reaction of the alkenyl sulfonate, the resulting polyalkenyl sulfonic acid compound reduces the crystallinity of the mesoporous titanium dioxide, thereby significantly reducing its photocatalytic activity. The mesoporous titanium dioxide is mixed with cysteine ​​and heated to graft cysteine ​​into its pores. The presence of cysteine ​​allows the modified titanium dioxide to possess both good matting properties and suppressed photocatalytic activity, preventing damage to the fiber structure from prolonged ultraviolet irradiation when applied to polyester fibers. However, the existing technology has a technical problem: it does not improve the anti-aging properties of polyester fibers by further improving the titanium dioxide preparation process. Summary of the Invention

[0004] The purpose of this invention is to provide a titanium dioxide filler for polyester and its preparation method, which solves the technical problem in the prior art that the titanium dioxide preparation process has not been further improved to enhance the anti-aging properties of polyester fibers.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a titanium dioxide filler specifically for polyester includes the following steps: S1. Grind and screen the titanium concentrate, magnetically separate it, acid wash it, wash it with water until neutral, and dry it to obtain pretreated titanium concentrate. S2. Add the pretreated titanium concentrate to sulfuric acid for acid hydrolysis. Add titanium dioxide return material during the acid hydrolysis stage, filter to remove solid impurities, add iron powder for reduction, add a settling agent to settle impurities, filter to remove impurities, cool down to crystallize and remove ferrous sulfate, and concentrate to obtain crude titanium sulfate solution. S3. Add crude titanium sulfate solution to seed crystals, heat and hydrolyze, filter and collect the solid to obtain crude metatitanic acid. S4. After washing the crude metatitanic acid once with water, add it to sulfuric acid, add aluminum powder to bleach, filter and collect the solid, wash it twice with water until neutral, and obtain low-iron metatitanic acid. S5. After dispersing low-iron metatitanic acid in water to obtain low-iron metatitanic acid slurry, add phosphoric acid, potassium carbonate, cerium sulfate and zinc sulfate and stir. Filter the mixture and filter it to obtain filter cake. Calcine the filter cake, cool it and grind it to obtain crude titanium dioxide. S6. Crude titanium dioxide is crushed and ground, then mixed with deionized water to obtain titanium dioxide slurry. Polysiloxane is added for modification, dried, crushed, and packaged to obtain a titanium dioxide filler for polyester.

[0006] Preferably, the chemical composition of the titanium concentrate in S1 is as follows: 49-52% titanium dioxide, 6-8% iron oxide, 28-30% ferrous oxide, 2-3% silicon dioxide, 0.01-0.03% calcium oxide, 0.2-0.4% magnesium oxide, 0.6-0.8% aluminum oxide, 0.5-0.8% manganese oxide, 0.01-0.03% sulfur, and 0.005-0.02% phosphorus, with the balance being unavoidable impurities, gangue minerals, and moisture.

[0007] Preferably, in step S1, the material is crushed to a 300-325 mesh sieve with a passing rate greater than 90%, and most of the magnetic iron minerals are removed using a strong magnetic separator with a magnetic field strength of 0.5-1.5T. Then, the material is acid-washed with sulfuric acid of 10-15wt% at 60-80℃ and a stirring speed of 150-250rpm for 1-3 hours, with a solid-liquid ratio of 1:8-10 during the acid washing stage. Finally, the material is dried at 105-120℃ for 4-8 hours.

[0008] Preferably, the sulfuric acid concentration in S2 is 85-92 wt%, and it is acidified at 180-200℃ for 8-10 hours. The solid-liquid ratio during the acidification stage is 1:1.3-1.6. The titanium dioxide return material is a titanium dioxide semi-finished product generated during the research and development stage that does not meet the requirements of particle size, whiteness, viscosity, filtration performance, or dispersibility. The mass of the titanium dioxide return material is 10-13% of the mass of the pretreated titanium concentrate. After the concentration of trivalent titanium is detected to be 1-5 g / L during the iron powder addition reduction process, a settling agent is added and settling is carried out at 60-80℃ for 2-4 hours. The settling agent is polyacrylamide, and the amount of settling agent added is 5-15 mg / L. The temperature is then lowered to 10-15℃ for crystallization. The titanium content in the crude titanium sulfate solution is 150-220 g / L, and the iron content is 1-3 g / L.

[0009] Preferably, the seed crystal in S3 is anatase seed crystal, and the amount of seed crystal added is 1.5~2wt% of the mass of crude titanium sulfate solution. The solution is heated to 98~105℃ for slight boiling hydrolysis for 30~60min, and after gray spots appear, it is kept at the temperature for 120~180min for ripening.

[0010] Preferably, the concentration of sulfuric acid in S4 is 5-7 wt%, the amount of aluminum powder added is 0.3-0.5 wt% of the mass of crude metatitanic acid, bleaching is performed at 60-70℃ for 60-90 min, and the iron content of the low-iron metatitanic acid is less than 50 ppm.

[0011] Preferably, the concentration of the low-iron metatitanic acid slurry in S5 is 280~320g / L, and the mass ratio of phosphoric acid, potassium carbonate, zinc sulfate, cerium sulfate and low-iron metatitanic acid is 0.1~0.2:0.15~0.3:0.15~0.3:0.2~0.3:100, and it is stirred at room temperature at a speed of 500~800rpm for 1~2h.

[0012] Preferably, in step S5, the temperature is increased to 400-450℃ at a heating rate of 5-8℃ / min and calcined for 30-50 minutes, then increased to 650-700℃ at a heating rate of 5-8℃ / min and calcined for 60-90 minutes, and finally increased to 880-920℃ at a heating rate of 15-25℃ / min and calcined for 60-120 minutes.

[0013] Preferably, in step S6, the titanium dioxide is pulverized to a 500-600 mesh sieve with a passing rate of more than 90%, the concentration of the titanium dioxide slurry is 350-450 g / L, the amount of polysiloxane added is 0.3-0.5% of the mass of the crude titanium dioxide, the mixture is stirred and modified at 500-800 rpm at 60-80°C for 1-2 hours, and then dried at 100-120°C.

[0014] An application of titanium dioxide filler specifically for polyester fibers includes the following preparation steps: S11. Dry the polyethylene terephthalate resin and set it aside for later use; S12. Polyethylene terephthalate resin, polyester-specific titanium dioxide filler and weather-resistant additives are added to a mixer and mixed. The mixture is then added to an extruder for melt extrusion, pelletized, and cooled to obtain weather-resistant masterbatch. S13. After mixing weather-resistant masterbatch and polyethylene terephthalate resin, heat and melt them in a screw extruder, spun through a spinneret, solidify and shape them in cooling air, apply oil, stretch and wind them through hot rollers, and cool them to obtain polyester fibers.

[0015] Preferably, the S11 is dried at 100~110°C until the moisture content is less than 0.005%.

[0016] Preferably, the mass ratio of polyethylene terephthalate resin, polyester-specific titanium dioxide filler, and weather-resistant additive in S12 is 100:5~10:0.5~2. The temperature settings of each zone of the extruder are as follows: Zone 1 230~250℃, Zone 2 250~260℃, Zone 3 255~265℃, Zone 4 240~250℃, Die head 260~270℃, and screw speed is 40~70rpm.

[0017] Preferably, in S13, the spinning temperature is 270~300℃, the extrusion pressure is 10~20MPa, the spinning speed is 1000~1500m / min, the spinneret orifice diameter is 0.2~0.5mm, the cooling airflow velocity is 2~3m / s, the hot roller temperature is 80~150℃, the stretching ratio is 1.5~3, and the winding speed is 3000~4000m / min.

[0018] The preparation method of the weather-resistant additive includes the following preparation steps: S21. Triethanolamine, hexadecyltrimethylammonium bromide template agent and deionized water are mixed, and tetraethyl orthosilicate is added dropwise under stirring to precipitate. The solid is collected by filtration, washed with deionized water and added to anhydrous ethanol. Hydrochloric acid is added and ultrasonically removed to remove the template agent. The solid is collected by filtration, washed with deionized water and dried to obtain mesoporous silica. S22. Add mesoporous silica to deionized water, add anhydrous calcium chloride until the solution is supersaturated, heat and stir to mix, filter to collect the solid, let stand to impregnate, and dry to obtain dyeing silica. S22. Mix the dyeing-promoting silica and the composite antioxidant to prepare a weather-resistant additive.

[0019] Preferably, the ratio of triethanolamine, hexadecyltrimethylammonium bromide template agent, deionized water and tetraethyl orthosilicate in S21 is (2~3) mL: (1~1.5) g: (200~300) mL: (2~3) mL. The mixture is stirred at 500~700 rpm for 1~2 h, the hydrochloric acid concentration is 36~37 wt%, the volume ratio of anhydrous ethanol to hydrochloric acid is 25~30:1, the mixture is ultrasonicated at 50~60℃ with a power of 30~50W for 1~2 h, and dried at 50~60℃ for 4~6 h.

[0020] Preferably, in step S22, the mixture is stirred at 300-500 rpm at 50-60°C for 1-2 hours, allowed to stand and soak for 4-6 hours, and then dried at 50-60°C for 2-4 hours.

[0021] Preferably, the composite antioxidant in S23 is prepared by mixing antioxidant 1010, antioxidant 1076 and antioxidant 168 in a mass ratio of 1~1.3:1.5~2:1, and the mass ratio of the composite antioxidant to the dyeing-promoting silica is 0.8~1:1.

[0022] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention uses high-grade titanium concentrate to reduce iron impurity content, employs sulfuric acid hydrolysis to control the uniform particle size distribution of titanium dioxide, and improves the dispersion stability of titanium dioxide. Cerium sulfate is introduced as a synergistic stabilizer for phosphoric acid, potassium carbonate, and zinc sulfate. The ionic radius effect of cerium further inhibits the anatase to rutile phase transition during calcination, improving the thermal stability of the anatase crystal form. Surface modification with polysiloxane can improve the compatibility of titanium dioxide with polyester and reduce the risk of spinneret clogging during spinning.

[0023] 2. The present invention provides dyeing-promoting silica prepared by loading calcium chloride onto mesoporous silica. The silica surface has silanol groups and is weakly acidic. Calcium chloride can neutralize some of the acidic sites, inhibiting the thermal oxidative degradation of polyester during high-temperature processing. The calcium ions generated by hydrolysis can improve the dyeing rate of polyester fibers by complexing the amide groups of nylon fibers. Furthermore, it can promote the composite antioxidant to inhibit the problems of fiber yellowing, embrittlement and strength reduction caused by thermal oxidative aging during long-term use of polyester, ensuring the smoothness of the spinning process and the lifespan of polyester fibers.

[0024] 3. In this invention, the combined action of titanium dioxide and weather-resistant additives avoids the problems of poor spinnability and uneven performance of polyester fibers caused by titanium dioxide agglomeration, and finally obtains high-quality polyester fibers with excellent anti-aging and excellent durability. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of a method for preparing a polyester-specific titanium dioxide filler according to the present invention is shown. Detailed Implementation

[0027] 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.

[0028] The polysiloxane involved in this invention is model JP-208C, the polyethylene terephthalate resin is model EP-T121 with a viscosity of 0.68 dL / g, the oiling agent is model TF-702T, and the chemical composition of the titanium concentrate is as follows: titanium dioxide 52%, iron oxide 7%, ferrous oxide 28.5%, silicon dioxide 2.7%, calcium oxide 0.015%, magnesium oxide 0.2%, aluminum oxide 0.6%, manganese oxide 0.5%, sulfur 0.02%, and phosphorus 0.01%, with the balance being unavoidable impurities, gangue minerals, and water.

[0029] Example 1: A method for preparing a polyester-specific titanium dioxide filler, comprising the following steps: S1. Grind and screen the titanium concentrate to a 300-mesh sieve with a passing rate of more than 90%. Use a strong magnetic separator with a magnetic field strength of 0.5T for magnetic separation. Use 10wt% sulfuric acid at 60℃ and 150rpm for 1h with stirring. The solid-liquid ratio during the acid washing stage is 1:8. Wash with water until neutral and dry at 105℃ for 4h to obtain pretreated titanium concentrate. S2. 1t of pretreated titanium concentrate was added to 1.3t of 85wt% sulfuric acid for acid hydrolysis. During the acid hydrolysis stage, 0.1t of titanium dioxide return material was added. Solid impurities were removed by filtration. Iron powder was added for reduction. After the concentration of trivalent titanium was measured to be 1g / L, polyacrylamide flocculant was added and the mixture was settled at 60℃ for 2h to settle impurities. The amount of flocculant added was 5mg / L. Impurities were removed by filtration. The mixture was cooled to 10℃ to crystallize and remove ferrous sulfate. The mixture was concentrated to obtain crude titanium sulfate solution. The titanium content in the crude titanium sulfate solution was 150g / L and the iron content was 1g / L. S3. Add 1t of crude titanium sulfate solution to 15kg of anatase seed crystals and heat to 98℃ for 30min of gentle boiling hydrolysis. After gray spots appear, keep warm and mature for 120min. Filter under pressure to collect the solid and obtain crude metatitanic acid. S4. Wash 1 t of crude metatitanic acid with water and add it to 5 wt% sulfuric acid. Add 3 kg of aluminum powder and bleach at 60℃ for 60 min. Filter and collect the solid. Wash it twice with water until neutral to obtain low iron metatitanic acid. The iron content of the low iron metatitanic acid is less than 50 ppm. S5. Disperse 1 t of low-iron metatitanic acid in water to prepare a low-iron metatitanic acid slurry with a concentration of 280 g / L. Then add 1 kg of phosphoric acid, 1.5 kg of potassium carbonate, 1.5 kg of cerium sulfate and 2 kg of zinc sulfate. Stir at room temperature for 1 hour at 500 rpm. Filter the mixture to obtain a filter cake. Calcinate the filter cake at 400℃ for 30 min at a heating rate of 5℃ / min. Then calcine it at 650℃ for 60 min at a heating rate of 5℃ / min. Finally, calcine it at 880℃ for 60 min at a heating rate of 15℃ / min. After cooling, grind the mixture to obtain crude titanium dioxide. S6. Grind 1 t of crude titanium dioxide to a 500 mesh sieve with a passing rate of more than 90%, add it to deionized water and slurry to obtain a titanium dioxide slurry of 350 g / L, add 3 kg of polysiloxane and stir at 500 rpm at 60℃ for 1 hour to modify it, dry it at 100℃, pulverize it and package it to obtain a titanium dioxide filler for polyester.

[0030] An application of titanium dioxide filler specifically for polyester fibers includes the following preparation steps: S11. Dry the polyethylene terephthalate resin at 100℃ until the moisture content is less than 0.005%, and set aside for later use; S12. Add 100 kg of polyethylene terephthalate resin, 5 kg of polyester-specific titanium dioxide filler, and 0.5 kg of weather-resistant additive to a mixer and mix. Then add the mixture to an extruder for melt extrusion. The temperature settings for each zone of the extruder are as follows: Zone 1 230℃, Zone 2 250℃, Zone 3 255℃, Zone 4 240℃, Die head 260℃, screw speed 40 rpm. Pelletize and cool to obtain weather-resistant masterbatch. S13. Weather-resistant masterbatch and polyethylene terephthalate resin are mixed and heated to melt in a screw extruder. The spinning temperature is 270℃, the extrusion pressure is 10MPa, and the fibers are spun through a spinneret at a speed of 1000m / min with a spinneret orifice diameter of 0.2mm. The fibers are then cured and shaped in a cooling airflow of 2m / s, oiled, stretched and wound by hot rollers at a temperature of 80℃, a stretch ratio of 1.5, and a winding speed of 3000m / min. After cooling, polyester fibers are obtained.

[0031] The preparation method of the weather-resistant additive in this embodiment includes the following preparation steps: S21. Mix 20 mL of triethanolamine, 10 g of hexadecyltrimethylammonium bromide template agent and 2 L of deionized water. Add 20 mL of tetraethyl orthosilicate dropwise while stirring at 500 rpm for 1 h. Filter to collect the solid, wash with deionized water and add to anhydrous ethanol. Add 36 wt% hydrochloric acid (volume ratio of anhydrous ethanol to hydrochloric acid is 25:1). Sonicate at 50 °C with 30 W power for 1 h. Dry at 50 °C for 4 h to remove the template agent. Filter to collect the solid, wash with deionized water and dry at 50 °C for 4 h to obtain mesoporous silica. S22. Add 100g of mesoporous silica to 500mL of deionized water, add anhydrous calcium chloride until the solution is supersaturated, heat to 50℃ and stir at 300rpm for 1h, filter to collect the solid, let it stand and soak for 4h, and dry at 50℃ for 2h to obtain dyeing silica. S23. The composite antioxidant is prepared by mixing antioxidant 1010, antioxidant 1076 and antioxidant 168 in a mass ratio of 1:1.5:1. The weather-resistant auxiliary agent is prepared by mixing 100g of dyeing-promoting silica and 80g of composite antioxidant.

[0032] Example 2: A method for preparing a polyester-specific titanium dioxide filler according to this example includes the following steps: S1. Grind and screen the titanium concentrate to a 325-mesh sieve with a passing rate of more than 90%. Use a strong magnetic separator with a magnetic field strength of 1.5T for magnetic separation. Acid wash with 15wt% sulfuric acid at 80℃ and 250rpm for 3h with stirring. The solid-liquid ratio during the acid washing stage is 1:10. Wash with water until neutral and dry at 120℃ for 8h to obtain pretreated titanium concentrate. S2. 1t of pretreated titanium concentrate was added to 1.6t of 92wt% sulfuric acid for acid hydrolysis. During the acid hydrolysis stage, 0.13t of titanium dioxide return material was added. Solid impurities were removed by filtration. Iron powder was added for reduction. After the concentration of trivalent titanium was measured to be 5g / L, polyacrylamide flocculant was added and the mixture was settled at 80℃ for 4h to settle impurities. The amount of flocculant added was 15mg / L. Impurities were removed by filtration. The mixture was cooled to 15℃ to crystallize and remove ferrous sulfate. The mixture was concentrated to obtain crude titanium sulfate solution. The titanium content in the crude titanium sulfate solution was 220g / L and the iron content was 3g / L. S3. Add 1 t of crude titanium sulfate solution to 20 kg of anatase seed crystals and heat to 105℃ for slight boiling hydrolysis for 60 min. After gray spots appear, keep warm and mature for 180 min. Filter under pressure to collect the solid and obtain crude metatitanic acid. S4. Wash 1 t of crude metatitanic acid with water and add it to 7 wt% sulfuric acid. Add 5 kg of aluminum powder and bleach at 70℃ for 90 min. Filter and collect the solid. Wash it twice with water until neutral to obtain low-iron metatitanic acid. The iron content of the low-iron metatitanic acid is less than 50 ppm. S5. After dispersing 1 t of low-iron metatitanic acid in water to obtain a low-iron metatitanic acid slurry with a concentration of 320 g / L, add 2 kg of phosphoric acid, 3 kg of potassium carbonate, 3 kg of cerium sulfate and 3 kg of zinc sulfate. Stir at room temperature for 2 hours at 800 rpm. Filter the mixture to obtain a filter cake. Calcinate the filter cake at 450°C for 50 minutes at a heating rate of 8°C / min, then at 700°C for 90 minutes at a heating rate of 8°C / min, and finally at 920°C for 120 minutes at a heating rate of 25°C / min. After cooling, grind the mixture to obtain crude titanium dioxide. S6. 1 ton of crude titanium dioxide is crushed and ground until the passing rate of a 600-mesh sieve is greater than 90%. It is then added to deionized water and slurryed to obtain a titanium dioxide slurry of 450 g / L. 5 kg of polysiloxane is added and the mixture is stirred at 800 rpm at 80°C for 2 hours to modify it. The mixture is then dried at 120°C, crushed, and packaged to obtain a titanium dioxide filler for polyester.

[0033] This embodiment describes the application of a titanium dioxide filler specifically for polyester fibers, comprising the following preparation steps: S11. Dry the polyethylene terephthalate resin at 110℃ until the moisture content is less than 0.005%, and set aside for later use; S12. Add 100 kg of polyethylene terephthalate resin, 10 kg of polyester-specific titanium dioxide filler, and 2 kg of weather-resistant additive to a mixer and mix. Then add the mixture to an extruder for melt extrusion. The temperature settings for each zone of the extruder are as follows: Zone 1 250℃, Zone 2 260℃, Zone 3 265℃, Zone 4 250℃, Die head 270℃, screw speed 70 rpm. Pelletize and cool to obtain weather-resistant masterbatch. S13. Weather-resistant masterbatch and polyethylene terephthalate resin are mixed and heated to melt in a screw extruder. The spinning temperature is 300℃, the extrusion pressure is 20MPa, and the fibers are spun through a spinneret at a speed of 1500m / min and a spinneret orifice diameter of 0.5mm. The fibers are then cured and shaped in a cooling airflow of 3m / s, oiled, stretched and wound by hot rollers at a temperature of 150℃, a stretch ratio of 3, and a winding speed of 4000m / min. After cooling, polyester fibers are obtained.

[0034] The preparation method of the weather-resistant additive in this embodiment includes the following preparation steps: S21. Mix 30 mL of triethanolamine, 15 g of hexadecyltrimethylammonium bromide template agent and 3 L of deionized water. Add 30 mL of tetraethyl orthosilicate dropwise while stirring at 700 rpm for 2 h. Filter to collect the solid, wash with deionized water and add to anhydrous ethanol. Add 36 wt% hydrochloric acid (volume ratio of anhydrous ethanol to hydrochloric acid is 30:1). Sonicate at 60 °C with 50 W power for 2 h. Dry at 60 °C for 6 h to remove the template agent. Filter to collect the solid, wash with deionized water and dry at 60 °C for 6 h to obtain mesoporous silica. S22. Add 100g of mesoporous silica to 500mL of deionized water, add anhydrous calcium chloride until the solution is supersaturated, heat to 60℃ and stir at 500rpm for 2h, filter to collect the solid, let it stand and soak for 6h, and dry at 60℃ for 4h to obtain dyeing silica. S23. The composite antioxidant is prepared by mixing antioxidant 1010, antioxidant 1076 and antioxidant 168 in a mass ratio of 1.3:2:1. The weather-resistant auxiliary agent is prepared by mixing 100g of dyeing-promoting silica and 100g of composite antioxidant.

[0035] Example 3: A method for preparing a polyester-specific titanium dioxide filler according to this example includes the following steps: S1. Grind and screen the titanium concentrate to a 310 mesh sieve with a passing rate of more than 90%, and perform magnetic separation using a strong magnetic separator with a magnetic field strength of 0.7T. Then, use 11wt% sulfuric acid at 65℃ and a stirring speed of 180rpm for 2 hours to pickle the concentrate. The solid-liquid ratio during the pickling stage is 1:9. Wash the concentrate with water until it is neutral, and dry it at 110℃ for 5 hours to obtain pretreated titanium concentrate. S2. 1t of pretreated titanium concentrate was added to 1.4t of 86wt% sulfuric acid for acid hydrolysis. During the acid hydrolysis stage, 0.11t of titanium dioxide return material was added. Solid impurities were removed by filtration. Iron powder was added for reduction. After the concentration of trivalent titanium was measured to be 2g / L, polyacrylamide flocculant was added and the mixture was allowed to settle at 65℃ for 2.5h to settle impurities. The amount of flocculant added was 8mg / L. Impurities were removed by filtration. The mixture was cooled to 11℃ to crystallize and remove ferrous sulfate. The mixture was then concentrated to obtain crude titanium sulfate solution. The titanium content in the crude titanium sulfate solution was 160g / L and the iron content was 1.5g / L. S3. Add 1t of crude titanium sulfate solution to 16kg of anatase seed crystals and heat to 100℃ for slight boiling hydrolysis for 40min. After gray spots appear, keep warm and mature for 140min. Filter under pressure to collect the solid and obtain crude metatitanic acid. S4. Wash 1 t of crude metatitanic acid with water and add it to 5.5 wt% sulfuric acid. Add 3.5 kg of aluminum powder and bleach at 62℃ for 70 min. Filter and collect the solid. Wash it twice with water until neutral to obtain low-iron metatitanic acid. The iron content of the low-iron metatitanic acid is less than 50 ppm. S5. After dispersing 1 t of low-iron metatitanic acid in water to obtain a low-iron metatitanic acid slurry with a concentration of 290 g / L, add 1.2 kg of phosphoric acid, 2 kg of potassium carbonate, 2 kg of cerium sulfate and 2.2 kg of zinc sulfate. Stir at room temperature for 1.2 h at 600 rpm. Filter the mixture to obtain a filter cake. Calcinate the filter cake at 410 °C for 35 min at a heating rate of 6 °C / min, then at 6 °C / min for 70 min, and finally at 890 °C for 80 min at a heating rate of 18 °C / min. After cooling, grind the mixture to obtain crude titanium dioxide. S6. 1 ton of crude titanium dioxide was crushed and ground until the passing rate of a 520 mesh sieve was greater than 90%. It was then added to deionized water and pulped to obtain a titanium dioxide slurry of 380 g / L. 3.5 kg of polysiloxane was added and the mixture was stirred at 600 rpm at 65°C for 1.2 h to modify it. The mixture was then dried at 105°C, crushed, and packaged to obtain a titanium dioxide filler for polyester.

[0036] An application of titanium dioxide filler specifically for polyester fibers includes the following preparation steps: S11. Dry the polyethylene terephthalate resin at 102℃ until the moisture content is less than 0.005%, and set aside for later use; S12. Add 100 kg of polyethylene terephthalate resin, 6 kg of polyester-specific titanium dioxide filler, and 1 kg of weather-resistant additive to a mixer and mix. Then add the mixture to an extruder for melt extrusion. The temperature settings for each zone of the extruder are as follows: Zone 1 235℃, Zone 2 252℃, Zone 3 258℃, Zone 4 242℃, Die head 262℃, screw speed 50 rpm. Pelletize and cool to obtain weather-resistant masterbatch. S13. Weather-resistant masterbatch and polyethylene terephthalate resin are mixed and heated to melt in a screw extruder. The spinning temperature is 280℃, the extrusion pressure is 12MPa, and the fibers are spun through a spinneret at a speed of 1100m / min and a spinneret orifice diameter of 0.3mm. The fibers are then cured and shaped in a cooling airflow at a velocity of 2.2m / s, oiled, stretched and wound by hot rollers at a temperature of 90℃, a stretch ratio of 1.8, and a winding speed of 3200m / min. After cooling, polyester fibers are obtained.

[0037] The preparation method of the weather-resistant additive in this embodiment includes the following preparation steps: S21. Mix 22 mL of triethanolamine, 11 g of hexadecyltrimethylammonium bromide template agent and 2.2 L of deionized water. Add 22 mL of tetraethyl orthosilicate dropwise while stirring at 550 rpm for 1.2 h. Filter to collect the solid, wash with deionized water and add to anhydrous ethanol. Add 36 wt% hydrochloric acid (volume ratio of anhydrous ethanol to hydrochloric acid is 26:1). Sonicate at 52 °C with 35 W power for 1.2 h. Dry at 52 °C for 4.5 h to remove the template agent. Filter to collect the solid, wash with deionized water and dry at 52 °C for 4.5 h to obtain mesoporous silica. S22. Add 100g of mesoporous silica to 500mL of deionized water, add anhydrous calcium chloride until the solution is supersaturated, heat to 52℃ and stir at 350rpm for 1.2h, filter to collect the solid, let it stand and soak for 4.5h, and dry at 52℃ for 2.5h to obtain dyeing silica. S23. The composite antioxidant is prepared by mixing antioxidant 1010, antioxidant 1076 and antioxidant 168 in a mass ratio of 1.1:1.6:1. The weather-resistant agent is prepared by mixing 100g of dyeing-promoting silica and 85g of composite antioxidant.

[0038] Comparative Example 1 differs from Example 1 in that the filter cake was directly heated to 900°C for 150 min at a heating rate of 10°C / min, and then cooled to prepare crude titanium dioxide.

[0039] Comparative Example 2 differs from Example 1 in that polysiloxane is replaced with trimethylolpropane.

[0040] Comparative Example 3 differs from Example 1 in that the weathering agent is replaced with fumed silica with an average particle size of 500 nm.

[0041] Performance testing The basic physicochemical properties of the titanium dioxide prepared in Example 1 were measured, and the test results are shown in Table 1 below: Table 1 Basic physical and chemical properties According to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", the breaking strength and elongation at break of polyester fibers prepared in each example and comparative example were measured using an electronic tensile testing machine. Each group was measured 5 times, and the average value was taken.

[0042] The polyester fibers obtained in each embodiment and comparative example were woven into plain weave fabrics, cut into 50mm×50mm sizes, dyed with 3g of disperse blue 2BLN dye at a liquor ratio of 1:100, and acetic acid was added during the dyeing process to adjust the pH to 4.5. The dyeing was carried out at 90℃ for 30 minutes, washed with water, and dried to obtain fabric samples. The uniformity grade of the fabric samples was determined according to the color chart.

[0043] According to GB / T 31899-2015 "Textiles - Weather Resistance Tests - Ultraviolet Light Exposure", the plain weave fabrics prepared in each example and comparative example were placed under a 340nm ultraviolet lamp with an irradiance of 0.89W / m². 2 The fabrics were irradiated at a blackboard temperature of 60°C for 8 hours, followed by condensation at a blackboard temperature of 50°C for 4 hours. This process was repeated 100 times, and the color change level of the plain weave fabrics prepared in each embodiment and comparative example was measured.

[0044] The test results are shown in Table 2 below: Table 2 Properties of Polyester Fibers As shown in Table 2, the tensile strength of the polyester fibers prepared in Examples 1-5 is 3.84-3.86 cN / dtex, and the elongation at break is 29.5-30.3%. This indicates that the titanium dioxide prepared in this invention can be uniformly dispersed in polyester fibers and improve their mechanical properties. The dyeing uniformity of the polyester fibers prepared in Examples 1-5 is grade 5, and the color change grade after UV aging is grade 4. This indicates that the titanium dioxide prepared in this invention can promote the dyeing of polyester fibers and has excellent UV oxidation resistance.

[0045] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0046] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A titanium dioxide filler specifically for polyester, characterized in that, The preparation method includes the following steps: S1. Grind and screen the titanium concentrate, magnetically separate it, acid wash it, wash it with water until neutral, and dry it to obtain pretreated titanium concentrate. S2. Add the pretreated titanium concentrate to sulfuric acid for acid hydrolysis. Add titanium dioxide return material during the acid hydrolysis stage, filter to remove solid impurities, add iron powder for reduction, add a settling agent to settle impurities, filter to remove impurities, cool down to crystallize and remove ferrous sulfate, and concentrate to obtain crude titanium sulfate solution. S3. Add crude titanium sulfate solution to seed crystals, heat and hydrolyze, filter and collect the solid to obtain crude metatitanic acid. S4. After washing the crude metatitanic acid once with water, add it to sulfuric acid, add aluminum powder to bleach, filter and collect the solid, wash it twice with water until neutral, and obtain low-iron metatitanic acid. S5. After dispersing low-iron metatitanic acid in water to obtain low-iron metatitanic acid slurry, add phosphoric acid, potassium carbonate, cerium sulfate and zinc sulfate and stir. Filter the mixture and filter it to obtain filter cake. Calcine the filter cake, cool it and grind it to obtain crude titanium dioxide. S6. Crude titanium dioxide is crushed and ground, added to deionized water and slurried to obtain titanium dioxide slurry, modified with polysiloxane, dried, crushed and packaged to obtain a titanium dioxide filler for polyester.

2. The titanium dioxide filler for polyester as described in claim 1, characterized in that, In step S1, the material is pulverized to a 300-325 mesh sieve with a passing rate greater than 90%. Most of the magnetic iron minerals are removed using a strong magnetic separator with a magnetic field strength of 0.5-1.5T. The material is then acid-washed with 10-15wt% sulfuric acid at 60-80℃ and a stirring speed of 150-250rpm for 1-3 hours, with a solid-liquid ratio of 1:8-10 during the acid washing stage. The material is then dried at 105-120℃ for 4-8 hours. In step S2, the sulfuric acid concentration is 85-92wt%, and the material is acid-hydrolyzed at 180-200℃ for 8-10 hours, with a solid-liquid ratio of 1:1.3-1.6 during the acid hydrolysis stage. Titanium dioxide reclaimed material refers to titanium dioxide semi-finished products generated during the research and development stage that do not meet the requirements for particle size, whiteness, viscosity, filtration performance, or dispersibility. The mass of titanium dioxide reclaimed material is 10-13% of the mass of pretreated titanium concentrate. After adding iron powder during the reduction process, the concentration of trivalent titanium is detected to be 1-5 g / L. Then, a settling agent is added and the mixture is settling at 60-80℃ for 2-4 hours. The settling agent is polyacrylamide, and the amount of settling agent added is 5-15 mg / L. The mixture is then cooled to 10-15℃ for crystallization. The titanium content in the crude titanium sulfate solution is 150-220 g / L, and the iron content is 1-3 g / L.

3. The titanium dioxide filler for polyester as described in claim 1, characterized in that, The seed crystal in S3 is anatase, and the amount of seed crystal added is 1.5~2wt% of the mass of crude titanium sulfate solution. It is heated to 98~105℃ for gentle boiling hydrolysis for 30~60min. After gray spots appear, it is kept at the temperature for 120~180min for aging. The concentration of sulfuric acid in S4 is 5~7wt%, and the amount of aluminum powder added is 0.3~0.5wt% of the mass of crude metatitanic acid. It is bleached at 60~70℃ for 60~90min. The iron content of the low-iron metatitanic acid is less than 50ppm.

4. The titanium dioxide filler for polyester as described in claim 1, characterized in that, The concentration of the low-iron metatitanic acid slurry in S5 is 280~320 g / L. The mass ratio of phosphoric acid, potassium carbonate, zinc sulfate, cerium sulfate and low-iron metatitanic acid is 0.1~0.2:0.15~0.3:0.15~0.3:0.2~0.3:

100. The mixture is stirred at room temperature at 500~800 rpm for 1~2 hours, then heated to 400~450℃ at a heating rate of 5~8℃ / min and calcined for 30~50 minutes. Finally, the temperature is increased to 650℃ at a heating rate of 5~8℃ / min. Calcination at ~700℃ for 60~90min, followed by heating to 880~920℃ at a rate of 15~25℃ / min and calcination for 60~120min; in step S6, the titanium dioxide is pulverized to a 500~600 mesh sieve with a passing rate greater than 90%, the concentration of the titanium dioxide slurry is 350~450g / L, the amount of polysiloxane added is 0.3~0.5% of the mass of the crude titanium dioxide, and the mixture is stirred and modified at 60~80℃ at a speed of 500~800rpm for 1~2h, and then dried at 100~120℃.

5. The application of the polyester-specific titanium dioxide filler according to any one of claims 1-4, characterized in that, For use in polyester fibers, the following preparation steps are included: S11. Dry the polyethylene terephthalate resin and set it aside for later use; S12. Polyethylene terephthalate resin, polyester-specific titanium dioxide filler and weather-resistant additives are added to a mixer and mixed. The mixture is then added to an extruder for melt extrusion, pelletized, and cooled to obtain weather-resistant masterbatch. S13. After mixing weather-resistant masterbatch and polyethylene terephthalate resin, heat and melt them in a screw extruder, spun through a spinneret, solidify and shape them in cooling air, apply oil, stretch and wind them through hot rollers, and cool them to obtain polyester fibers.

6. The application of the titanium dioxide filler for polyester as described in claim 5, characterized in that, In S11, the material is dried at 100~110℃ until the moisture content is less than 0.005%; in S12, the mass ratio of polyethylene terephthalate resin, polyester-specific titanium dioxide filler, and weather-resistant additive is 100:5~10:0.5~2. The temperature settings of each zone of the extruder are as follows: Zone 1 230~250℃, Zone 2 250~260℃, Zone 3 255~265℃, Zone 4 240~250℃, Die head 260~270℃, and screw speed is 40~70rpm.

7. The application of the titanium dioxide filler for polyester as described in claim 5, characterized in that, In S13, the spinning temperature is 270~300℃, the extrusion pressure is 10~20MPa, the spinning speed is 1000~1500m / min, the spinneret orifice diameter is 0.2~0.5mm, the cooling airflow velocity is 2~3m / s, the hot roller temperature is 80~150℃, the stretch ratio is 1.5~3, and the winding speed is 3000~4000m / min.

8. The application of the titanium dioxide filler for polyester as described in claim 5, characterized in that, The preparation method of the weather-resistant additive includes the following preparation steps: S21. Triethanolamine, hexadecyltrimethylammonium bromide template agent and deionized water are mixed, and tetraethyl orthosilicate is added dropwise under stirring to precipitate. The solid is collected by filtration, washed with deionized water and added to anhydrous ethanol. Hydrochloric acid is added and ultrasonically removed to remove the template agent. The solid is collected by filtration, washed with deionized water and dried to obtain mesoporous silica. S22. Add mesoporous silica to deionized water, add anhydrous calcium chloride until the solution is supersaturated, heat and stir to mix, filter to collect the solid, let stand to impregnate, and dry to obtain dyeing silica. S22. Mix the dyeing-promoting silica and the composite antioxidant to prepare a weather-resistant additive.

9. The application of the titanium dioxide filler for polyester according to claim 5, characterized in that, In S21, the ratio of triethanolamine, hexadecyltrimethylammonium bromide template agent, deionized water, and tetraethyl orthosilicate is (2~3) mL : (1~1.5) g : (200~300) mL : (2~3) mL. The mixture is stirred at 500~700 rpm for 1~2 hours. The hydrochloric acid concentration is 36~37 wt%, and the volume ratio of anhydrous ethanol to hydrochloric acid is 25~30:

1. The mixture is then sonicated at 50~60℃ with a power of 30~50 W for 1~ 2h, then dry at 50~60℃ for 4~6h; in S22, stir at 300~500rpm at 50~60℃ for 1~2h, let stand and impregnate for 4~6h, then dry at 50~60℃ for 2~4h; in S23, the composite antioxidant is prepared by mixing antioxidant 1010, antioxidant 1076 and antioxidant 168 in a mass ratio of 1~1.3:1.5~2:1, and the mass ratio of composite antioxidant to dyeing-promoting silica is 0.8~1:1.

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