Preparation method of fibrous potassium hexatitanate

Abstract

The invention discloses a preparation method of fibrous potassium hexatitanate, which comprises the following steps: uniformly mixing organic amine and a titanium-containing compound, and adding alcohol; heating the mixture, adding a potassium-containing compound in the heating process, and uniformly mixing again; adding a spinning aid into the obtained mixture, and then carrying out microfluidic spinning; finally, a sample obtained after spinning is calcined, and fibrous potassium hexatitanate is finally prepared. The preparation method is simple to operate, short in production period, free of waste acid emission, low in cost, environment-friendly and efficient. The average diameter of the prepared fibrous potassium hexatitanate is larger than or equal to 15 micrometers, the fibrous potassium hexatitanate is in a thick rod shape and uniform in morphology, the mechanical property and stability of the composite material can be remarkably improved, and the fibrous potassium hexatitanate is not prone to being sucked into the human body and entering blood or lymph.

Description

Technical Field

[0001] The present invention relates to the field of material preparation, and in particular to a method for preparing fibrous potassium hexatitanate. Background Art

[0002] Potassium hexatitanate whiskers (K2Ti6O 13 Potassium titanate whiskers are a layered inorganic non-metallic material with a white, needle-like or fibrous crystal structure approximately 1 μm in diameter. Whiskers of this size are generally considered potentially carcinogenic. However, due to their excellent mechanical properties, thermal stability, chemical stability, and insulating properties, they are widely used in composite reinforcement (such as rubber and ceramics), thermal insulation (such as coatings and refractory materials), and as an asbestos replacement in friction materials (such as clutches and brake pads). However, due to their small particle size, traditional potassium titanate whiskers are easily inhaled into the human body and enter the blood or lymph. The International Labor Organization (LO) and the Deutsche Forschungsgemeinschaft (DFG) define fibers as inhalable if they have a diameter of 3 μm or less, a length of 5 μm or less, and an aspect ratio of 3 or more. These fibers have a potential carcinogenic risk, and some Western countries, including the European Union, have banned the use of potassium titanate whiskers in friction applications. Therefore, the preparation of large-diameter potassium titanate whiskers with diameters exceeding 3 μm is a current research focus.

[0003] Chinese patent CN115216841B proposes a method for preparing potassium hexatitanate whiskers (K2Ti6O 13 This method uses potassium titanate and titanium oxide as raw materials, with KCl and K2O-MoO3 as co-solvents. Key process parameters include a molar ratio of K2CO3 to TiO2 of 5.5, and a molar ratio of KCl, K2O-MoO3 to K2CO3 of 3. After mixing the raw materials and sintering at 920-980°C, K2Ti6O3 with uniform diameter distribution and a large aspect ratio can be obtained. 13 Whiskers. These whiskers are suitable for friction materials such as ceramic brake pads and have good economic value. However, the potassium hexatitanate whiskers produced by this method have a diameter of less than 1 μm, which is still harmful to the human body. In addition, they contain halogen ions (mainly from KCl), which can cause corrosion to production equipment.

[0004] Chinese patent CN119286259A describes a method for preparing vinyl-modified potassium hexatitanate whiskers: a 20% solids slurry is prepared by mixing potassium carbonate and metatitanic acid in a 5:1 molar ratio. The precursor is filtered, dried, crushed, and sintered at 700°C for 1.5 hours. Ethanol is then added, and after stirring, vinyltris(2-methoxyethoxy)silane and water are introduced. The product is then ball-milled and sieved. The resulting whiskers have an aspect ratio of up to 50 and a diameter of up to 2 μm. However, this method has the following disadvantages: the whisker purity is low, the use of the organic solvent ethanol causes environmental pollution, and the 2 μm diameter is still within the range of inhalable fibers.

[0005] In summary, how to regulate the morphology of potassium hexatitanate whiskers has not yet been solved. Summary of the Invention

[0006] Purpose of the invention: The present invention provides a method for preparing fibrous potassium hexatitanate with large diameter and adjustable length.

[0007] Summary of the invention: To achieve the above-mentioned object, the present invention provides a method for preparing fibrous potassium hexatitanate, comprising the following steps: (1) Mixing the organic amine and the titanium-containing compound uniformly; (2) adding alcohol to the mixture obtained in step (1) and mixing uniformly; (3) heating the mixture obtained in step (2), adding a potassium-containing compound during the heating process, and mixing again; (4) adding a spinning aid to the mixture obtained in step (3); (5) performing microfluidic spinning on the solution obtained in step (4); (6) The sample obtained after spinning in step (5) is calcined to obtain fibrous potassium hexatitanate.

[0008] Preferably, in step (1), the organic amine is one or more of diethanolamine, triethylamine, N,N-dimethylformamide, and triethanolamine.

[0009] Preferably, in step (1), the titanium-containing compound is one or more of tetrabutyl titanate, metatitanic acid, titanium oxide, and tetraisopropyl titanate.

[0010] Preferably, in step (1), the molar ratio of the organic amine to the titanium-containing compound is 1.5:1 to 5:1.

[0011] Preferably, in step (3), the potassium-containing compound is one or more of potassium formate, potassium acetate, potassium hydroxide, potassium carbonate, and potassium chloride.

[0012] Preferably, in step (3), the mixture obtained in step (2) is heated, and a potassium-containing compound is added during the heating process, wherein the TiO2 / K2O molar ratio is controlled to be 4:1-6:1; and the heating temperature is 30-70°C.

[0013] Preferably, in step (4), the spinning aid is one or more of polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide or polymethyl cellulose.

[0014] Preferably, in step (5), the microfluidic spinning speed is 2-5 ml / h, the temperature is 30-50 °C, and the spinning needle is one of No. 19, No. 20 or No. 21.

[0015] Preferably, in step (6), the calcination temperature is 700-900°C, and the calcination rate is 1-5°C / min.

[0016] Preferably, in step (6), the diameter of the prepared fibrous potassium hexatitanate is ≥15 μm, and the length is adjustable.

[0017] Preferably, the mixing is carried out by stirring, kneading or ball milling.

[0018] The preparation method of the present invention innovatively combines the sol-gel method with microfluidic spinning technology, utilizes the laminar flow effect dominated by surface tension and viscosity in micron-scale channels, and regulates the preparation of potassium hexatitanate fibers by controlling the spinning speed, temperature, and spinning needle size. It breaks through the technical bottlenecks of traditional electrospinning with large diameter fluctuations (CV>20%) and easy fiber breakage in sol spinning, and realizes the micron-level controllable preparation of potassium hexatitanate fibers.

[0019] Beneficial effects: Compared with the existing technology, the present invention has significant effects: the preparation method of the present invention is simple to operate, has a short production cycle, and adopts a sol-gel method combined with microfluidic spinning technology to prepare potassium hexatitanate fibers, without waste acid discharge, environmentally friendly and efficient. The average diameter of the prepared potassium hexatitanate fibers is ≥15 μm, and they are thick rod-shaped with uniform morphology. They can significantly improve the mechanical properties and stability of the composite materials, and are not easily inhaled into the human body and enter the blood or lymph. In addition, by regulating the process parameters, the crystal morphology is changed from needle-shaped to coarse fiber-shaped, meeting the specific requirements of different application scenarios for material morphology. The present invention provides a new technical path for the green production and high-performance application of potassium hexatitanate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a scanning electron microscope image of potassium hexatitanate prepared in Example 1 of the present invention; Figure 2 This is a Raman graph of potassium hexatitanate prepared in Example 1 of the present invention; Figure 3This is a scanning electron microscope image of potassium hexatitanate prepared in Example 2 of the present invention; Figure 4 This is a Raman graph of potassium hexatitanate prepared in Example 2 of the present invention; Figure 5 This is a scanning electron microscope image of potassium hexatitanate prepared in Example 3 of the present invention; Figure 6 This is a Raman graph of potassium hexatitanate prepared in Example 3 of the present invention; Figure 7 This is a scanning electron microscope image of potassium hexatitanate prepared in Comparative Example 1 of the present invention; Figure 8 This is the Raman graph of potassium hexatitanate prepared in Comparative Example 1 of the present invention; Figure 9 This is a scanning electron microscope image of potassium hexatitanate prepared in Comparative Example 2 of the present invention; Figure 10 This is the Raman graph of potassium hexatitanate prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The materials, reagents, instruments, etc. used in the examples are all commercially available unless otherwise specified. It should be understood that the following specific embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Example 1

[0022] Tetrabutyl titanate (TBOT), triethylamine, potassium acetate (CH3COOK), and methanol were used as raw materials. The raw materials were weighed to a molar ratio of organic amine to titanium-containing compound of 1.5. 10 g of methanol was added, and the mixture was heated to 30°C and magnetically stirred until uniformly mixed. Potassium acetate was then weighed to a TiO2:K2O ratio of 4 and continued to stir until uniformly mixed. 0.08 g of polyethylene oxide (PEO) was added to the mixture and stirred until the solution reached a certain viscosity. The resulting spinning solution was microfluidically spun using a 19-gauge needle at a controlled spinning temperature of 30°C and a spinning speed of 2 ml / h. The resulting sample was placed in a muffle furnace and heated from 25°C to 700°C at a rate of 1°C / min. The temperature was maintained for 2 hours, then cooled in the furnace and the sintered product was removed.

[0023] Figure 1 is a scanning electron microscope image of potassium hexatitanate prepared in this example, Figure 2 This is the Raman diagram of potassium hexatitanate prepared in this example. Figure 1 It can be concluded that the fibers are in the form of continuous long rods rather than whiskers, showing excellent structural integrity. Figure 2 Spectral analysis showed that the﹣1 The characteristic peak at is similar to that of standard potassium hexatitanate (K2Ti6O 13 ), confirming that the product is a single-phase potassium hexatitanate crystal. Example 2

[0024] Tetrabutyl titanate (TBOT), triethanolamine, potassium acetate (CH3COOK), and ethanol were used as raw materials. The raw materials were weighed to a molar ratio of organic amine to titanium-containing compound of 3. 10 g of methanol was added, and the mixture was heated to 50°C and magnetically stirred until uniformly mixed. Potassium acetate was then weighed to a TiO2:K2O ratio of 5.5, and stirring was continued until uniformly mixed. 0.1 g of polyvinylpyrrolidone (PVP) was added to the mixture, and the solution was stirred until it reached a certain viscosity. The resulting spinning solution was microfluidically spun using a 20-gauge needle at a controlled spinning temperature of 40°C and a spinning speed of 4 ml / h. The resulting sample was placed in a muffle furnace and heated from 25°C to 800°C at a rate of 2°C / min. The temperature was maintained at this temperature for 2 h, after which it was cooled in the furnace and the sintered product was removed.

[0025] Figure 3 is a scanning electron microscope image of potassium hexatitanate prepared in this example, Figure 4 This is the Raman diagram of potassium hexatitanate prepared in this example. Figure 3 It can be concluded that the fibers are in the form of continuous long rods rather than whiskers, showing excellent structural integrity. Figure 4 Spectral analysis showed that the ﹣1 The characteristic peak at is similar to that of standard potassium hexatitanate (K2Ti6O 13 ), confirming that the product is a single-phase potassium hexatitanate crystal. Example 3

[0026] Tetrabutyl titanate (TBOT), triethylamine, potassium acetate (CH3COOK), and methanol were used as raw materials. The raw materials were weighed to a molar ratio of organic amine to titanium-containing compound of 5. 10 g of methanol was added, and the mixture was heated to 70°C and magnetically stirred until uniformly mixed. Potassium acetate was then weighed to a ratio of TiO2:K2O of 6, and stirring continued until uniformly mixed. 0.13 g of polyethylene oxide (PEO) was added to the mixture, and the solution was stirred until it reached a certain viscosity. The resulting spinning solution was microfluidically spun using a 21-gauge needle at a controlled spinning temperature of 50°C and a spinning speed of 5 ml / h. The resulting sample was placed in a muffle furnace and heated from 25°C to 900°C at a rate of 5°C / min. The temperature was maintained for 2 h, then cooled in the furnace and the sintered product was removed.

[0027] Figure 5 is a scanning electron microscope image of potassium hexatitanate prepared in this example, Figure 6 This is the Raman diagram of potassium hexatitanate prepared in this example. Figure 5 It can be concluded that the fibers are in the form of continuous long rods rather than whiskers, showing excellent structural integrity. Figure 6 Spectral analysis showed that the ﹣1 The characteristic peak at is similar to that of standard potassium hexatitanate (K2Ti6O 13 ), confirming that the product is a single-phase potassium hexatitanate crystal. Comparative Example 1

[0028] Tetrabutyl titanate, potassium acetate (CH3COOK), and methanol were used as raw materials. The raw materials were weighed to a ratio of TiO2:K2O = 4. 10g of methanol was added and mixed thoroughly. 0.08g of polyethylene oxide (PEO) was then added. The mixture was heated to 30°C. The resulting spinning solution was microfluidically spun using a 19-gauge needle at a controlled spinning temperature of 30°C and a spinning speed of 2 ml / h. The resulting sample was placed in a muffle furnace and heated from 25°C to 700°C at a rate of 1°C / min. The temperature was maintained at this temperature for 2 hours, then cooled in the furnace and the sintered product was removed.

[0029] Figure 7 is a scanning electron microscope image of potassium hexatitanate prepared in this comparative example, Figure 8 It is the Raman diagram of potassium hexatitanate prepared in this comparative example. Figure 7 The potassium titanate fibers that can be obtained are formed by stacking long whiskers. Figure 8 Spectral analysis showed that the ﹣1 The characteristic peak at is similar to that of standard potassium hexatitanate (K2Ti6O 13 ), which basically matches the Raman peak of the product, confirming that the product is a single-phase potassium hexatitanate crystal. Comparative Example 2

[0030] Tetrabutyl titanate (TBOT), triethylamine, potassium acetate (CH3COOK), and methanol were used as raw materials. The raw materials were weighed to a molar ratio of organic amine to titanium-containing compound of 6. 10 g of methanol was added, and the mixture was heated to 70°C and magnetically stirred until uniformly mixed. Potassium acetate was then weighed to a ratio of TiO2:K2O of 6, and stirring was continued until uniformly mixed. 0.13 g of polyethylene oxide (PEO) was added to the mixture, and the solution was stirred until it reached a certain viscosity. The resulting spinning solution was microfluidically spun using a 21-gauge needle, maintaining a spinning temperature of 50°C and a spinning speed of 5 ml / h. If spinning was unsuccessful, the sample was placed in a muffle furnace and heated from 25°C to 900°C at a rate of 5°C / min. The temperature was maintained for 2 hours, then cooled in the furnace and the sintered product was removed.

[0031] Figure 9 is a scanning electron microscope image of potassium hexatitanate prepared in this comparative example, Figure 10 It is the Raman diagram of potassium hexatitanate prepared in this comparative example. Figure 9 The potassium titanate that can be obtained is formed by the accumulation of whiskers. Figure 10 Spectral analysis showed that the ﹣1 The characteristic peak at is similar to that of standard potassium hexatitanate (K2Ti6O 13 ), which basically matches the Raman peak of the product, confirming that the product is a single-phase potassium hexatitanate crystal.

Claims

1. A method for preparing fibrous potassium hexatitanate, characterized in that: The following steps are involved: (1) Mixing the organic amine and the titanium-containing compound uniformly; (2) adding alcohol to the mixture obtained in step (1) and mixing uniformly; (3) heating the mixture obtained in step (2), adding a potassium-containing compound during the heating process, and mixing again; (4) adding a spinning aid to the mixture obtained in step (3); (5) performing microfluidic spinning on the solution obtained in step (4); (6) The sample obtained after spinning in step (5) is calcined to obtain fibrous potassium hexatitanate.

2. The method for preparing fibrous potassium hexatitanate according to claim 1, wherein: In step (1), the organic amine is one or more of diethanolamine, triethylamine, N,N-dimethylformamide, and triethanolamine.

3. The method for preparing fibrous potassium hexatitanate according to claim 1, wherein: In step (1), the titanium-containing compound is one or more of tetrabutyl titanate, metatitanic acid, titanium oxide, and tetraisopropyl titanate.

4. The method for preparing fibrous potassium hexatitanate according to claim 1, wherein: In step (1), the molar ratio of the organic amine to the titanium-containing compound is 1.5:1 to 5:

1.

5. The method for preparing fibrous potassium hexatitanate according to claim 1, wherein: In step (3), the potassium-containing compound is one or more of potassium formate, potassium acetate, potassium hydroxide, potassium carbonate, and potassium chloride.

6. The method for preparing fibrous potassium hexatitanate according to claim 1, wherein: In step (3), the mixture obtained in step (2) is heated, and a potassium-containing compound is added during the heating process, wherein the TiO2 / K2O molar ratio is controlled to be 4:1~6:1; and the heating temperature is 30~70°C.

7. The method for preparing fibrous potassium hexatitanate according to claim 1, wherein: In step (4), the spinning aid is one or more of polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide or polymethyl cellulose.

8. The method for preparing fibrous potassium hexatitanate according to claim 1, wherein: In step (5), the microfluidic spinning speed is 2-5 ml / h, the temperature is 30-50 °C, and the spinning needle is one of No. 19, No. 20 or No.

21.

9. The method for preparing fibrous potassium hexatitanate according to claim 1, wherein: In step (6), the calcination temperature is 700-900°C, and the calcination rate during the calcination process is 1-5°C / min.

10. The method for preparing fibrous potassium hexatitanate according to claim 1, wherein: In step (6), the diameter of the prepared fibrous potassium hexatitanate is ≥15 μm, and the length is adjustable.

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