Preparation method and application of dispersed nano boehmite

Abstract

The invention relates to the technical field of preparation of nano boehmite, in particular to a preparation method and application of dispersed nano boehmite. The preparation method comprises the following steps: mixing an interfacial agent, urea and an aluminum salt aqueous solution through a sol-gel method to form a uniformly dispersed boehmite precursor solution; then, carrying out aging treatment on the precursor solution to form an aging reaction material; and finally, carrying out hydrothermal reaction to obtain a nano boehmite product with good dispersity under the conditions of high temperature and high pressure. According to the preparation method, a three-stage synergistic mechanism of uniform nucleation, dual stable agglomeration inhibition of an interfacial activity regulating agent and crystal face selective adsorption guide morphology evolution is realized through a urea slow-release alkaline environment, the technical bottlenecks of poor dispersity and uncontrollable morphology in traditional boehmite preparation are broken through, and finally, the preparation method has the advantages that the preparation efficiency is high, and the preparation cost is low. The purity of the obtained dispersing type nano boehmite is up to 99.9% or above, and the dispersing type nano boehmite has excellent physical properties.

Description

Technical Field

[0001] The present application relates to the technical field of nano-boehmite preparation, and in particular to a preparation method of dispersed nano-boehmite and its application. Background Art

[0002] Microporous photo paper is a high-quality printing material used in inkjet printers. Its coating consists of a gloss layer, an image-forming layer, and a solvent-absorbing layer. The gloss layer, also known as the ink-receptive coating, is crucial for inkjet printing quality. The ink-receptive coating leverages the material's strong adsorption capacity to effectively secure ink and prevent color blending, thereby ensuring high-definition, vibrant surfaces, and lifelike color reproduction in printed photos. Currently, two commonly used ink-receptive materials are microsilica and nanoalumina. Microsilica has a large surface area and strong ink absorption capacity, but it is also expensive and has high viscosity. While nanoalumina exhibits excellent absorption speed for water-based inks, its ink absorption performance is subpar, with insufficient gloss and poor dispersibility. Compared to nanosilica and nanoalumina, nanoboehmite offers the advantages of low cost, environmental friendliness, and low hardness. When used in an ink-receptive coating, nanoboehmite offers high gloss, vibrant colors, and excellent dispersibility, making it a promising nanomaterial alternative to traditional microsilica and nanoalumina.

[0003] At present, the preparation technology of nano-boehmite includes the following: (1) dispersing pseudo-boehmite in deionized water, then adding inorganic acid or inorganic base and stirring evenly to obtain a dispersed raw material; then adding special additives to the dispersed raw material and mixing evenly again to obtain a mixed raw material; then adding the mixed raw material to a high-pressure reactor for hydrothermal reaction to obtain a reaction product; after cooling the reaction product, washing and spraying are performed to obtain nano-boehmite. (2) keeping a mixed solution of inorganic acid and sodium metaaluminate with a pH of 9 to 14 at 80°C to 90°C, then adding the mixed solution to a reactor and reacting at 120°C to 160°C for 4h to 12h to obtain a reaction product; washing, drying and granulating the reaction product to finally obtain nano-boehmite. (3) Add any surfactant such as sodium dodecyl sulfate, sodium alkyl polyoxyethylene ether sulfate, sodium fatty acid, sodium alkyl sulfate to a mixed solution of aluminum salt solution and caustic soda to obtain a reaction solution; adjust the pH value of the reaction solution to between 7 and 10, stir it thoroughly, inject it into a high-pressure reactor, keep it at 120°C for 2 hours, and obtain a reaction solution again. The reaction solution is cooled, then filtered, washed, dried and ground in sequence to finally obtain boehmite nanocrystals. (4) Neutralize the mixed solution of aluminum chloride and sodium metaaluminate at 60°C to 90°C to obtain a reaction solution; then adjust the pH value of the reaction solution by circulating and aging to prepare pseudo-boehmite with a primary particle diameter of 2nm to 30nm. These pseudo-boehmite are subjected to a series of treatments: washing, drying, roasting and cooling, and finally nano-boehmite with large pore volume, high specific surface area and strong adsorption capacity is obtained. (5) adding a sodium aluminate solution to a mixed solution of nano-aluminum hydroxide, a dispersant, and water to form a mixture; introducing carbon dioxide into the mixture while stirring it under heating conditions until the pH of the mixture is 7 to 11, thereby obtaining a precursor suspension; then subjecting the fully homogenized precursor suspension to solid-liquid separation, washing, and beating in sequence to obtain a reaction solution; then transferring the reaction solution to a reactor and keeping it warm at 180° C. to 210° C., thereby finally obtaining nano-boehmite.

[0004] However, the nano-boehmite prepared by these existing nano-boehmite preparation technologies is prone to agglomeration, and the morphological characteristics of the prepared nano-boehmite are poor, which affects its application in microporous photographic paper. Summary of the Invention

[0005] The present application provides a preparation method of dispersed nano-boehmite and its application to solve the following technical problems: how to improve the dispersibility of nano-boehmite and optimize the morphological characteristics of nano-boehmite.

[0006] In a first aspect, the present invention provides a method for preparing dispersed nano-boehmite, the method comprising:

[0007] Mixing a surfactant modifier, urea and an aluminum salt aqueous solution to obtain a reaction raw material;

[0008] aging the reaction raw materials so that the aluminum salt in the reaction raw materials forms nano-boehmite crystals, thereby obtaining an aged reaction material;

[0009] The aged reaction material is subjected to a hydrothermal reaction, so that the interfacial activity regulator of the aged material controls the nucleation and growth of the nano-boehmite crystals, thereby obtaining a reaction material containing a dispersed nano-boehmite product.

[0010] The mass proportion of the interfacial activity modifier can be selected to be 0.1% to 1.0% of the mass of the reaction raw materials.

[0011] Optionally, the surfactant is selected from at least one of the following: sodium oleate, polyethylene glycol fatty acid esters and xylitol; and / or

[0012] The aluminum salt in the aluminum salt aqueous solution is selected from at least one of the following: aluminum nitrate, aluminum sulfate and aluminum chloride.

[0013] Optionally, the interfacial activity modifier, urea and aluminum salt aqueous solution are mixed to obtain the reaction raw materials, comprising the steps of:

[0014] mixing an aluminum salt and a hydrophilic solvent under a preset temperature condition to obtain an aluminum salt aqueous solution;

[0015] Mixing urea and the aluminum salt aqueous solution to obtain a mixed solution with a preset pH;

[0016] The surfactant modifier and the mixed solution with the preset pH are mixed for the third time to obtain a reaction raw material.

[0017] Optionally, the preset temperature is 60° C. to 90° C.; and / or

[0018] The preset pH is 10 to 12.

[0019] Optionally, the solid content of the aluminum salt aqueous solution is 15 g / L to 25 g / L.

[0020] Optionally, the temperature of the hydrothermal reaction is 110° C. to 150° C., and the time of the hydrothermal reaction is 18 h to 30 h; and / or

[0021] The aging temperature is 60° C. to 90° C., and the aging time is 0.5 h to 3.0 h.

[0022] Optionally, the aged reaction material is subjected to a hydrothermal reaction so that the interfacial activity modifier of the aged material controls the nucleation and growth of the nano-boehmite crystals to obtain a reaction material containing a dispersed nano-boehmite product, followed by the steps of:

[0023] washing the reaction material containing the dispersed nano-boehmite product to obtain a washed material;

[0024] The washed material is spray-dried to obtain a dispersed nano-boehmite product.

[0025] In a second aspect, an embodiment of the present application provides a dispersed nano-boehmite, which is prepared by the preparation method described in the first aspect.

[0026] In a third aspect, an embodiment of the present application provides an ink-absorbing material, wherein the ink-absorbing material includes the dispersed nano-boehmite described in the second aspect.

[0027] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0028] The present application provides a method for preparing a dispersed nano-boehmite. The preparation method involves using an interfacial active modifier, urea, and an aqueous solution of aluminum salt as a reaction raw material system. Through the slow-release effect of urea, the pH of the aqueous solution of aluminum salt is adjusted to an alkaline environment, prompting the aluminum salt solution to be converted into aluminum hydroxide precursors of uniform size and uniform dispersion. These precursors form the initial crystal nuclei of boehmite during the aging process. In the hydrothermal reaction stage, the temperature of the hydrothermal reaction can activate the interfacial active modifier, and utilize its steric hindrance effect to prevent the initial boehmite nuclei and the boehmite crystals formed in the initial stage of the hydrothermal reaction from aggregating with each other, thereby improving dispersibility. At the same time, the electrostatic stabilization effect of the interfacial active modifier causes the initial boehmite nuclei and crystals to have the same charge. Based on the principle of charge repulsion, it is ensured that these initial nuclei and crystals are uniformly dispersed in the aging reaction material, further enhancing its dispersibility. In addition, the interfacial activity modifier can selectively adsorb on the surface of the boehmite crystal, inhibiting the growth of the boehmite crystal adsorbed with the interfacial activity modifier during the hydrothermal reaction, and promoting the crystal to grow in the direction where the interfacial activity modifier is not adsorbed, ultimately obtaining a boehmite product with a uniform morphology. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 A schematic diagram of the main process of a method for preparing dispersed nano-boehmite provided in an embodiment of the present application;

[0032] Figure 2 A schematic diagram of a detailed process for preparing a dispersed nano-boehmite according to an embodiment of the present application;

[0033] Figure 3 A schematic flow chart of a method for preparing dispersed nano-boehmite provided in an embodiment of the present application;

[0034] Figure 4 This is a scanning electron microscope image of a dispersed nano-boehmite provided in Example 1 of the present application. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] The range descriptions described in this application, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including" and "including" used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or simultaneously; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the text, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0037] It should be noted that, with respect to the prior art (1) described in the background art, the inventors found that the method used pseudo-boehmite as an aluminum source, which resulted in an excessively high cost of the aluminum source; and the inorganic acid used in the method caused serious corrosion to the equipment, posing a safety hazard. With respect to the prior art (2) described in the background art, the inventors found that the inorganic acid used in the method caused serious corrosion to the equipment, posing a safety hazard. With respect to the prior art (3) described in the background art, the inventors pointed out that the main problem of the technology was that the holding time was too short, resulting in poor key performance indicators such as the specific surface area, pore volume and pore size of the boehmite nanocrystals, making it difficult to meet the actual application requirements. With respect to the prior art (4) described in the background art, the inventors observed that the pseudo-boehmite prepared by the method had poor dispersibility, and the dispersibility of the nano-alumina obtained after calcination was further deteriorated. With respect to the prior art (5) described in the background art, the inventors found that the precursor used in the method was nano-aluminum hydroxide, which was expensive and not suitable for industrial production.

[0038] In summary, the nano-boehmite prepared by the above-mentioned nano-boehmite preparation method is easy to agglomerate and has poor morphological characteristics, thereby limiting its application in the field of microporous photographic paper.

[0039] Figure 1 The main flow chart of the preparation method of a dispersed nano-boehmite provided in the embodiment of the present application is exemplarily shown;

[0040] like Figure 1 As shown, the present invention provides a method for preparing dispersed nano-boehmite, which comprises:

[0041] S1. The surfactant modifier, urea and aluminum salt aqueous solution are mixed to obtain a reaction raw material;

[0042] S2. The reaction raw materials are aged so that the aluminum salt in the reaction raw materials forms nano-boehmite crystals to obtain an aged reaction material;

[0043] S3. subjecting the aged reaction material to a hydrothermal reaction, so that the interfacial activity modifier of the aged material controls the nucleation and growth of the nano-boehmite crystals, to obtain a reaction material containing a dispersed nano-boehmite product.

[0044] It is noteworthy that deionized water can be used as the solvent for the aluminum salt aqueous solution.

[0045] In addition, the hydrothermal reaction can be carried out in a high-pressure reactor, and the high-pressure conditions can effectively accelerate the hydrothermal reaction process.

[0046] It should be noted that the preparation method of dispersed nanoboehmite provided in the examples of this application achieves high dispersibility and morphological uniformity of nanoparticles through a multi-stage control mechanism. The specific principles are as follows:

[0047] 1. Slow release control and uniform nucleation in alkaline environment:

[0048] (1) Dynamic pH control of urea hydrolysis:

[0049] Urea is gradually hydrolyzed under the heating conditions of aging and hydrothermal reaction, continuously releasing NH3, causing the pH value of the solution to slowly transition from the initial acidic environment to alkaline.

[0050] In order to avoid local over-alkalinity, the traditional method of adding alkali directly can easily lead to a sharp change in the pH of the reaction raw materials, causing the aluminum salt in the aluminum salt aqueous solution to quickly precipitate into amorphous aluminum hydroxide, which in turn causes uneven particle size and easy agglomeration; the alkaline environment of urea slow release makes the aluminum ions (Al 3+ ) is uniformly hydrolyzed to form Al(OH)3 precursors of uniform size, laying the foundation for the subsequent uniform generation of boehmite (γ-AlOOH) crystal nuclei.

[0051] (2) Directed transformation of precursor to crystal nucleus:

[0052] During the aging stage, the Al(OH)3 precursor is gradually transformed into boehmite nuclei through dehydration condensation.

[0053] Uniformity of crystal nucleus size: The alkaline environment formed by the slow release of urea can prolong the nucleation period of boehmite crystal nuclei, promote the formation of small-sized, monodisperse crystal nuclei, and avoid the wide distribution of boehmite crystal nucleus size caused by too fast nucleation rate.

[0054] 2. Dual stabilization mechanism of surfactant modulators:

[0055] (1) Steric hindrance effect inhibits agglomeration:

[0056] The interfacial active modifier is activated in the hydrothermal reaction and can be adsorbed on the surface of the boehmite crystal core to form a densely coated adsorption layer.

[0057] Physical barrier effect: When the boehmite core particles approach each other due to Brownian motion, the steric hindrance of the adsorption layer will prevent the boehmite core particles from directly contacting each other, effectively inhibiting the agglomeration caused by van der Waals forces.

[0058] (2) Electrostatic stabilization enhances dispersibility:

[0059] The charged groups of the interfacial active agent can make the surface of the boehmite particles carry the same charge (generally negative), forming a double-layer structure.

[0060] Charge repulsion: The electrostatic repulsion between boehmite particles will offset the van der Waals attraction between boehmite core particles, maintaining the stable dispersion state of the boehmite core particles in the liquid phase.

[0061] 3. Selective adsorption on crystal surfaces and precise control of morphology:

[0062] (1) Differences in crystal growth dynamics:

[0063] The surface energy of different faces of boehmite crystals varies. Interfacial active agents preferentially adsorb on faces with high surface energy due to the adaptability of their molecular structures.

[0064] Growth inhibition effect: After the surface active agent is adsorbed on the surface of boehmite crystal, it effectively blocks the Al 3+ and OH - The contact of the ions causes the growth rate of the boehmite crystal in this area to drop significantly; while the unadsorbed crystal surface maintains a high growth activity.

[0065] (2) Implementation of morphology-directed evolution:

[0066] The formation mechanism of the flake structure is that the interfacial active modifier selectively adsorbs on the high surface energy crystal plane, prompting the boehmite crystal to expand two-dimensionally on the non-adsorbed crystal plane, and finally generating a flake boehmite product with uniform morphology.

[0067] Rod-like or spherical structure: Adjusting the type and concentration of the surfactant can change the crystal surface on which it is adsorbed and adjust the inhibitory effect on boehmite crystal growth, thereby producing rod-like or spherical boehmite products with different morphologies.

[0068] 4. Synergistic strengthening effect of hydrothermal reaction:

[0069] (1) High temperature and high pressure promote crystal maturation:

[0070] The hydrothermal reaction accelerates the dissolution and recrystallization process of the Al(OH)3 precursor, promoting the transformation of the boehmite nucleus toward a thermodynamically stable state to eliminate the lattice defects of the boehmite.

[0071] Improved morphology uniformity: In a continuous temperature field, the growth dynamics of boehmite crystals tend to be consistent, and combined with the dynamic adsorption balance of the interfacial active modifier, the morphology of the boehmite product is ensured to be highly uniform.

[0072] (2) Temperature dependence of regulator activity:

[0073] The high temperature of the hydrothermal reaction will enhance the molecular mobility of the surfactant, promote its dynamic balance of adsorption or desorption on the crystal surface, and optimize the uniformity and stability of the adsorption layer.

[0074] In summary, the embodiments of the present application provide a method for preparing dispersed nano-boehmite. This preparation method uses a three-level synergistic mechanism to achieve uniform nucleation through a slow-release alkaline environment of urea, dual stabilization inhibition of agglomeration by an interfacial active regulator, and selective adsorption on the crystal surface to guide morphology evolution. It successfully overcomes the technical difficulties of poor dispersion and difficult to control morphology in the traditional boehmite preparation process, and opens up an innovative path for the large-scale production of high-performance nano-boehmite.

[0075] In some optional embodiments, the mass of the interfacial activity modifier is 0.1% to 1.0% of the mass of the reaction raw materials.

[0076] In these embodiments, the interfacial active agent (whose mass is 0.1% to 1.0% of the mass of the reaction raw materials) can exhibit excellent steric hindrance effect, charge repulsion performance and selective adsorption characteristics, so that the boehmite crystal nuclei form boehmite products with uniform morphology and high dispersion under the action of the interfacial active agent.

[0077] The mass of the interfacial activity modifier can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1.0% of the mass of the reaction raw materials.

[0078] In some optional embodiments, the surfactant is selected from at least one of the following: sodium oleate, polyethylene glycol fatty acid esters, and xylitol; and / or

[0079] The aluminum salt in the aluminum salt aqueous solution is selected from at least one of the following: aluminum nitrate, aluminum sulfate and aluminum chloride.

[0080] In these embodiments, at least one of sodium oleate, polyethylene glycol fatty acid esters, or xylitol is used as a surfactant modifier, which exhibits excellent steric hindrance, charge repulsion, and selective adsorption. These properties, combined, enable boehmite nuclei to form a uniform and highly dispersed boehmite product under the influence of the modifier. Furthermore, an aqueous solution of at least one of aluminum nitrate, aluminum sulfate, and aluminum chloride can encompass a wide range of low-cost aluminum salt materials, effectively reducing the cost of the preparation method.

[0081] Figure 2 The following is a schematic diagram showing a detailed process flow of a method for preparing dispersed nano-boehmite provided in an embodiment of the present application;

[0082] In some optional embodiments, the interfacial activity modifier, urea and aluminum salt aqueous solution are mixed to obtain the reaction raw materials, comprising the steps of:

[0083] S101. The aluminum salt and the hydrophilic solvent are mixed under preset temperature conditions to obtain an aluminum salt aqueous solution;

[0084] S102. The urea and the aluminum salt aqueous solution are mixed to obtain a mixed solution having a preset pH;

[0085] S103. Perform a third mixing of the surfactant modifier and the mixed solution with the preset pH value to obtain a reaction raw material.

[0086] In these embodiments, the aluminum salt is mixed with a hydrophilic solvent to promote the aluminum salt to dissolve in the hydrophilic solvent with high solubility to form an aluminum salt aqueous solution, and then urea and the aluminum salt aqueous solution are mixed to form an alkaline environment formed by the hydrolysis and slow release of urea, so that the aluminum ions (Al2O3) in the aluminum salt aqueous solution are concentrated. 3+ ) is uniformly hydrolyzed to form a uniformly sized Al(OH)3 precursor, laying the foundation for the subsequent uniform formation of boehmite (γ-AlOOH) nuclei. Furthermore, due to the combined effects of the surfactant's steric hindrance, charge repulsion, and selective adsorption, the boehmite nuclei, under the influence of the surfactant, form a uniform and highly dispersed boehmite product.

[0087] In some optional embodiments, the preset temperature is 60° C. to 90° C.; and / or

[0088] The preset pH is 10 to 12.

[0089] In these embodiments, a preset temperature of 60°C to 90°C allows the aluminum salt to fully dissolve in the hydrophilic solvent, forming a uniformly distributed aluminum salt aqueous solution. Furthermore, this preset temperature facilitates the subsequent aging process, allowing the aluminum salt in the aluminum salt aqueous solution to form nano-boehmite crystals. Furthermore, a preset pH of 10 to 12 allows for the acidic and alkaline environment formed by the hydrolysis of urea. In this pH environment, the aluminum ions in the aluminum salt aqueous solution can be uniformly hydrolyzed to form uniformly sized Al(OH)3 precursors, which lay the foundation for the subsequent uniform formation of boehmite (γ-AlOOH) crystal nuclei.

[0090] The preset temperature may be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C.

[0091] The preset pH value can be selected as 10, 11 or 12.

[0092] In some optional embodiments, the solid content of the aluminum salt aqueous solution is 15 g / L to 25 g / L.

[0093] In these embodiments, the aluminum salt aqueous solution having a solid content of 15 g / L to 25 g / L can provide the aluminum salt aqueous solution with sufficient aluminum salt to form sufficient boehmite nuclei in the aging stage and sufficient boehmite crystals in the hydrothermal reaction stage.

[0094] The solid content of the aluminum salt aqueous solution can be 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, 20 g / L, 21 g / L, 22 g / L, 23 g / L, 24 g / L or 25 g / L.

[0095] In some optional embodiments, the temperature of the hydrothermal reaction is 110° C. to 150° C., and the time of the hydrothermal reaction is 18 h to 30 h; and / or

[0096] The aging temperature is 60° C. to 90° C., and the aging time is 0.5 h to 3.0 h.

[0097] In these embodiments, when the temperature of the hydrothermal reaction is set to 110°C to 150°C and the time is controlled to 18h to 30h, the activity of the surface active modifier can be effectively activated. Under the combined effects of steric hindrance, charge repulsion and selective adsorption, the surface active modifier can promote the formation of boehmite nuclei, thereby generating a boehmite product with uniform morphology and good dispersion. Under the temperature range of 60°C to 90°C and the time condition of 0.5h to 3.0h, the aging process can promote the slow hydrolysis of urea, thereby creating an alkaline environment. In the alkaline environment, the aluminum ions (Al2O3) of the aluminum salt aqueous solution are 3+ ) is uniformly hydrolyzed to form Al(OH)3 precursors of uniform size, laying the foundation for the subsequent uniform generation of boehmite (γ-AlOOH) crystal nuclei.

[0098] The temperature of the hydrothermal reaction may be 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, or 150°C.

[0099] The hydrothermal reaction time can be 18 h, 19 h, 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, 26 h, 27 h, 28 h, 29 h or 30 h.

[0100] The aging temperature may be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C.

[0101] The aging time may be 0.5 h, 1.0 h, 1.5 h, 2.0 h, 2.5 h or 3.0 h.

[0102] Figure 3 The following is a schematic flow chart of a method for preparing a dispersed nano-boehmite provided in an embodiment of the present application;

[0103] In some optional embodiments, the aged reaction material is subjected to a hydrothermal reaction so that the interfacial activity modifier in the aged material controls the nucleation and growth of the nano-boehmite crystals to obtain a reaction material containing a dispersed nano-boehmite product, followed by the steps of:

[0104] S4. The reaction mass containing the dispersed nano-boehmite product is washed to obtain a washed material;

[0105] S5. spray-drying the washed material to obtain a dispersed nano-boehmite product.

[0106] In these embodiments, the obtained reaction material containing the dispersed nano-boehmite product is first washed to remove water-soluble impurities such as unreacted raw materials; and then the washed material is dried and formed by spray drying to form a nano-boehmite product with good morphology and good dispersion.

[0107] It should be noted that the end point pH of the washing can be 7, so that the water-soluble impurities in the reaction material can be washed away; in addition, the spray drying temperature can be 200°C to 350°C, so that the washed material can be fully freed of water and other impurities under appropriate temperature conditions.

[0108] It should be noted that the spray drying time is determined by the flow rate of the water-washed material and the processing volume required.

[0109] It should be noted that, before washing the reaction mass, the reaction mass may be cooled to below 70°C.

[0110] Figure 4 The scanning electron microscope image of a dispersed nano-boehmite provided in Example 1 of the present application is exemplarily shown;

[0111] Based on a general inventive concept, such as Figure 4 As shown, the embodiment of the present application provides a dispersed nano-boehmite, and the dispersed nano-boehmite is prepared by the preparation method.

[0112] The dispersed nanoboehmite is prepared according to the above preparation method. The specific steps can be referred to the relevant embodiments. It integrates part or all of the technical solutions of the above embodiments, and thus inherits all the beneficial effects of these solutions. The detailed benefits are not repeated here.

[0113] It is worth noting that the dispersed nanoboehmite has a high purity of more than 99.9%, its original crystal size ranges from 50nm to 80nm, and its specific surface area is between 100m 2 / g to 130m 2 / g, and the pore volume is between 0.5mL / g and 0.6mL / g.

[0114] Based on a general inventive concept, an embodiment of the present application provides an ink-absorbing material, wherein the ink-absorbing material includes the dispersed nano-boehmite.

[0115] The ink-absorbing material is realized based on the above-mentioned dispersed nano-boehmite. The specific source of the dispersed nano-boehmite can be referred to the above-mentioned embodiment. Since the ink-absorbing material adopts part or all of the technical solutions of the above-mentioned embodiment, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here.

[0116] It should be noted that the dispersed nano-boehmite used in the ink-absorbing material has strong adsorption capacity due to its excellent dispersibility and morphological characteristics, especially its excellent specific surface area and pore volume, thus forming an ink-absorbing coating with excellent performance.

[0117] The present application is further described below with reference to specific examples. Experimental conditions not explicitly stated in the examples are generally carried out in accordance with national or industry standards; if there are no corresponding national or industry standards, they are carried out in accordance with common international standards, conventional operations, or conditions recommended by the manufacturer.

[0118] Example 1

[0119] like Figure 3 As shown, the embodiment of the present application provides a method for preparing dispersed nano-boehmite, comprising:

[0120] S101. The aluminum salt and the hydrophilic solvent are mixed under preset temperature conditions to obtain an aluminum salt aqueous solution;

[0121] S102. The urea and aluminum salt aqueous solution are mixed to obtain a mixture having a preset pH;

[0122] S103. The surfactant modifier and the mixture having a preset pH are mixed for a third time to obtain a reaction raw material;

[0123] S2. The reaction raw materials are aged so that the aluminum salt in the reaction raw materials forms nano-boehmite crystals to obtain an aged reaction material;

[0124] S3. The aging reaction material is subjected to a hydrothermal reaction, so that the interfacial active agent of the aging material controls the nucleation and growth of nano-boehmite crystals to obtain a reaction material containing a dispersed nano-boehmite product;

[0125] S4. The reaction mass containing the dispersed nano-boehmite product is washed to obtain a washed material;

[0126] S5. spray-drying the washed material to obtain a dispersed nano-boehmite product.

[0127] The interfacial activity regulator accounts for 0.9% of the total mass of the reaction raw materials.

[0128] The type of surfactant is sodium oleate;

[0129] The aluminum salt in the aluminum salt aqueous solution is aluminum nitrate.

[0130] The preset temperature is 90℃;

[0131] The default pH is 12.

[0132] The solid content of the aluminum salt aqueous solution is 15 g / L.

[0133] The temperature of the hydrothermal reaction was 120°C, and the time of the hydrothermal reaction was 30 h;

[0134] The aging temperature is 90°C and the aging time is 3.0 h.

[0135] Example 2

[0136] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0137] The mass of the interfacial activity regulator is 0.6% of the mass of the reaction raw materials.

[0138] The type of surfactant is fatty acid polyethylene glycol ester;

[0139] The aluminum salt in the aluminum salt aqueous solution is aluminum nitrate.

[0140] The preset temperature is 80℃;

[0141] The default pH is 11.

[0142] The solid content of the aluminum salt aqueous solution is 20 g / L.

[0143] The temperature of the hydrothermal reaction was 130°C, and the time of the hydrothermal reaction was 25 h;

[0144] The aging temperature is 80°C and the aging time is 2.0h.

[0145] Example 3

[0146] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0147] The mass of the interfacial activity regulator is 0.3% of the mass of the reaction raw materials.

[0148] The type of surfactant modifier is xylitol;

[0149] The aluminum salt in the aluminum salt aqueous solution is aluminum nitrate.

[0150] The preset temperature is 70℃;

[0151] The default pH is 10.

[0152] The solid content of the aluminum salt aqueous solution is 25 g / L.

[0153] The temperature of the hydrothermal reaction was 140°C, and the time of the hydrothermal reaction was 20 h;

[0154] The aging temperature is 70°C and the aging time is 1.0 h.

[0155] Comparative Example 1

[0156] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0157] No surfactant was added.

[0158] Comparative Example 2

[0159] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0160] The mass of the surfactant is 2.0% of the mass of the reaction raw materials.

[0161] Comparative Example 3

[0162] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0163] The preset temperature is 55℃.

[0164] Comparative Example 4

[0165] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0166] The preset temperature is 100℃.

[0167] Comparative Example 5

[0168] Compared with Example 2, the differences of this comparative example are as follows, and the rest are the same:

[0169] The default pH is 9.

[0170] Comparative Example 6

[0171] Compared with Example 3, the differences of this comparative example are as follows, and the rest are the same:

[0172] The temperature of the hydrothermal reaction was 160°C.

[0173] Comparative Example 7

[0174] Compared with Example 3, the differences of this comparative example are as follows, and the rest are the same:

[0175] The temperature of the hydrothermal reaction was 100°C.

[0176] Related experiments and effect data:

[0177] The dispersed nano-boehmite product obtained in Example 1 was observed under a FlexSEM1000 scanning electron microscope. Figure 4 The parameters of the scanning electron microscope are: 10 kV, 5.7 mm × 30.0; Figure 4 The scale bar in the middle is 1 μm. Figure 4 It can be seen that the dispersed nano-boehmite product obtained by the preparation method of Example 1 of the present application has a good specific surface area and a large pore volume, which indicates that the dispersed nano-boehmite product has an excellent surface morphology.

[0178] The dispersed nano-boehmite products of each embodiment and comparative example were collected, and their purity and surface characteristics were statistically analyzed. The results are shown in Table 1.

[0179] Table 1 Surface characteristics and purity of dispersed nano-boehmite products in various embodiments and comparative examples

[0180]

[0181] As shown in Table 1, the preparation method of a dispersed nano-boehmite provided in the embodiment of the present application achieves uniform nucleation through a slow-release alkaline environment of urea, dual stabilization of the surfactant to inhibit agglomeration, and a three-level synergistic mechanism of facet selective adsorption to guide morphology evolution. This method breaks through the technical bottlenecks of poor dispersibility and uncontrollable morphology in the preparation of traditional boehmite, so that the purity of the dispersed nano-boehmite obtained is above 99.9%, and the specific surface area reaches 100m 2 / g or more, the pore volume reaches 0.50mL / g or more, and the pore diameter reaches 15nm or more.

[0182] Compared with Example 1, Comparative Example 3 uses a higher preset temperature, which will cause the aluminum salt aqueous solution to boil, making the preparation method impossible to carry out and it is difficult to obtain the nano-boehmite product.

[0183] Compared to Example 3, Comparative Example 6 used a higher hydrothermal reaction temperature, which resulted in surface defects on the boehmite during the hydrothermal reaction, reducing the morphology of the boehmite product and reducing the specific surface area and pore volume of the boehmite product. Comparative Example 7 used a lower hydrothermal reaction temperature, which made the hydrothermal reaction difficult to proceed, ultimately making it difficult to obtain a nanoboehmite product.

[0184] In addition, the present application provides an embodiment of a method for preparing dispersed nano-boehmite, which uses urea and an aqueous solution of aluminum salt as raw materials, does not require the use of corrosive solutions such as inorganic acids, and is friendly to production equipment.

[0185] In addition, the dispersed nano-boehmite provided in the embodiment of the present application has good dispersibility, large specific surface area and large pore volume, so that the dispersed nano-boehmite has strong adsorption capacity and can be used as a raw material for ink-absorbing materials.

[0186] The foregoing is merely a detailed description of the present invention to enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing dispersed nano-boehmite, the method comprising: Mixing a surfactant modifier, urea and an aluminum salt aqueous solution to obtain a reaction raw material; aging the reaction raw materials so that the aluminum salt in the reaction raw materials forms nano-boehmite crystals, thereby obtaining an aged reaction material; The aged reaction material is subjected to a hydrothermal reaction, so that the interfacial activity regulator of the aged material controls the nucleation and growth of the nano-boehmite crystals, thereby obtaining a reaction material containing a dispersed nano-boehmite product.

2. The preparation method according to claim 1, characterized in that The mass of the interfacial activity regulator is 0.1% to 1.0% of the mass of the reaction raw materials.

3. The preparation method according to claim 1, characterized in that The surfactant is selected from at least one of the following: sodium oleate, polyethylene glycol fatty acid esters and xylitol; and / or The aluminum salt in the aluminum salt aqueous solution is selected from at least one of the following: aluminum nitrate, aluminum sulfate and aluminum chloride.

4. The preparation method according to claim 1, characterized in that The interfacial active agent, urea and aluminum salt aqueous solution are mixed to obtain the reaction raw materials, comprising the steps of: mixing an aluminum salt and a hydrophilic solvent under a preset temperature condition to obtain an aluminum salt aqueous solution; Mixing urea and the aluminum salt aqueous solution to obtain a mixed solution with a preset pH; The surfactant modifier and the mixed solution with the preset pH are mixed for the third time to obtain a reaction raw material.

5. The preparation method according to claim 4, characterized in that The preset temperature is 60°C to 90°C; and / or The preset pH is 10 to 12.

6. The preparation method according to claim 1 or 3, characterized in that The aluminum salt aqueous solution has a solid content of 15 g / L to 25 g / L.

7. The preparation method according to claim 1, characterized in that The temperature of the hydrothermal reaction is 110° C. to 150° C., and the time of the hydrothermal reaction is 18 h to 30 h; and / or The aging temperature is 60° C. to 90° C., and the aging time is 0.5 h to 3.0 h.

8. The preparation method according to claim 1, characterized in that The aged reaction material is subjected to a hydrothermal reaction, so that the interfacial activity modifier of the aged material controls the nucleation and growth of the nano-boehmite crystals to obtain a reaction material containing a dispersed nano-boehmite product, and then the steps of: washing the reaction material containing the dispersed nano-boehmite product to obtain a washed material; The washed material is spray-dried to obtain a dispersed nano-boehmite product.

9. A dispersed nano-boehmite, wherein the dispersed nano-boehmite is prepared by the preparation method according to any one of claims 1 to 8. 10 . An ink-absorbing material, comprising the dispersed nano-boehmite according to claim 9 .

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