Double metal layered hydroxide and method for producing the same

Abstract

The present invention provides a double metal layered hydroxide represented by the formula [M(II) 1‑x M(III) x (OH)2] x+ (A n‑ ) x / n ·mH2O, wherein M(II) contains a divalent cation selected from at least one of Mg, Zn, Ca, Ni, Co, Cu, Fe, Mn, and Sr, M(III) contains a trivalent cation selected from at least one of Al, Fe, Cr, Co, In, Ga, and V, A n‑ contains an anion selected from at least one of CO3 2‑ , OH ‑ , F ‑ , Cl ‑ , SO4 2‑ , NO3 ‑ , PO4 3‑ , B(OH) ‑ , VO4 3‑ , MnO4 ‑ , ClO4 ‑ , a carboxylate, a sulfonate, a sulfinic acid, and a thiocarboxylate, x is 0 < x < 1, n is the valence of A, and m is a number of 0 or more, and the double metal layered hydroxide has an average particle diameter D50 of 0.3 to 1.0 μm, a BET specific surface area of 8 to 25 m 2 / g, and a crystallite size of a D003 plane of 340 to 400 angstroms.

Description

Technical Field

[0001] This invention relates to bimetallic layered hydroxides and their preparation methods. Background Technology

[0002] Layered double hydroxides (LDHs) are a collective term for hydrotalcite (HT) and hydrotalcite-like compounds (HTLCs). They are hydroxides containing two or more metal ions and exhibiting a layered crystal structure. The layers are positively charged, and exchangeable anions exist between the layers. The general formula for layered double hydroxides is: [M(II)] 1-x M(Ⅲ) x (OH)2] x+ (A n- ) x / n ·mH2O, where M(Ⅱ) and M(Ⅲ) are divalent and trivalent metal cations, respectively, and A n- It is an interlayer anion.

[0003] Bimetallic layered hydroxides are a novel type of material. Their unique structure endows them with many special chemical and physical properties, such as interlayer ion exchange, adsorption, catalysis, memory effect, thermal stability, flame retardancy, and infrared absorption, while also exhibiting weak alkalinity. Therefore, they can be widely used in materials science, chemical engineering, pharmaceuticals, electromechanical engineering, agriculture, and environmental protection.

[0004] Traditional methods for synthesizing bimetallic layered hydroxides include the urea method, co-precipitation method, mechanochemical method, and hydrothermal synthesis method. Among these, the hydrothermal synthesis method is the most commonly used. This method involves mixing a metal salt solution with an alkaline solution, then transferring the mixture to a high-temperature heating reactor, maintaining the temperature for crystallization, and finally obtaining the final product through filtration and washing.

[0005] Traditional hydrothermal synthesis methods are characterized by their ability to produce fully crystalline products in a short time, but they suffer from drawbacks such as high water consumption and the presence of large amounts of salts, such as sodium salts, in the water. Various improvements have been proposed to address these issues.

[0006] Japanese Patent Application Publication No. 2004-99391 discloses a method for manufacturing layered composite hydroxides that does not produce byproducts such as sodium salts and requires no filtration or washing. However, this process is not conducive to the conversion of CO2 to CO3. 2- The conversion results in unreacted Al(OH)3 remaining in the final product, leading to low product purity.

[0007] CN101516781A discloses a method for producing layered double hydroxides, but because the average particle size of the slurry after grinding the raw materials is controlled within the range of 2.5~3.0μm, the raw materials after heat treatment cannot be completely converted into the hydrotalcite product with the target composition, and the resulting mixture also has poor dispersibility.

[0008] CN103108907B discloses a hydrotalcite with sodium content controlled in extremely small amounts and its manufacturing method, but the thermal stability and dispersibility of the hydrotalcite produced by this method do not meet the requirements.

[0009] In conclusion, there remains a demand for bimetallic layered hydroxides with excellent thermal stability and dispersibility.

[0010] Existing technical documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2004-99391

[0012] Patent Document 2: CN101516781A

[0013] Patent Document 3: CN103108907B Summary of the Invention

[0014] The problem that the invention aims to solve

[0015] There remains a need in this field for bimetallic layered hydroxides with excellent thermal stability and dispersibility.

[0016] Methods for solving problems

[0017] This invention was made to solve the above-mentioned technical problems, and provides a bimetallic layered hydroxide with excellent thermal stability and dispersibility, and a method for preparing the same.

[0018] Through in-depth research, the inventors have discovered that by controlling the particle size, specific surface area, and crystallite size of bimetallic layered hydroxides, bimetallic layered hydroxides with excellent thermal stability and dispersibility can be obtained. This invention also provides a method for preparing this bimetallic layered hydroxide, which is a green method using minimal water and low salt content in the water.

[0019] Specifically, the present invention provides:

[0020] 1. A bimetallic layered hydroxide, which is composed of formula [M(II)] 1-x M(Ⅲ) x (OH)2] x+ (A n- ) x / n ·mH2O means,

[0021] Among them, M(II) contains divalent cations selected from at least one of Mg, Zn, Ca, Ni, Co, Cu, Fe, Mn, Sr,

[0022] M(III) contains trivalent cations selected from at least one of Al, Fe, Cr, Co, In, Ga, V,

[0023] A n- contains anions selected from at least one of CO3 2- , OH - , F - , Cl - , SO4 2- , NO3 - , PO4 3- , B(OH) - , VO4 3- , MnO4 - , ClO4 - , carboxylate, sulfonate, sulfinate, thio-carboxylate,

[0024] x is 0 < x < 1, n is the valence of A, m is a number greater than or equal to 0,

[0025] The average particle size D50 of the double-metal layered hydroxide is 0.3 - 1.0 μm, the BET specific surface area is 8 - 25 m 2 / g, and the crystallite size of the d003 plane is 340 - 400 Å.

[0026] 2. The double-metal layered hydroxide according to 1, wherein the ratio of the interlayer distance of the d003 plane to the interlayer distance of the d006 plane deviates from the theoretical value of 2 within the range of ±0.25%.

[0027] 3. The double-metal layered hydroxide according to 1, wherein M(II) is at least one of Mg and Zn; M(III) is Al; A n- is CO3 2- .

[0028] 4. A preparation method of a double-metal layered hydroxide,

[0029] The double-metal layered hydroxide is represented by the formula [M(II) 1-x M(III) x (OH)2] x+ (A n- ) x / n ·mH2O,

[0030] Among them, M(II) contains divalent cations selected from at least one of Mg, Zn, Ca, Ni, Co, Cu, Fe, Mn, Sr,

[0031] M(III) contains a trivalent cation selected from at least one of Al, Fe, Cr, Co, In, Ga, V,

[0032] A n- contains an anion selected from at least one of CO3 2- , OH - , F - , Cl - , SO4 2- , NO3 - , PO4 3- , B(OH) - , VO4 3- , MnO4 - , ClO4 - , at least one of carboxylate, sulfonate, sulfinate, thio-carboxylate,

[0033] x is 0 < x < 1, n is the valence of A, and m is a number greater than or equal to 0,

[0034] The preparation method includes:

[0035] 1) Grind the M(II) source to an average particle size D50 ≤ 2.5 μm, and grind the M(III) source to an average particle size D50 ≤ 2.5 μm;

[0036] 2) Mix the above-ground raw materials, and continue to grind for more than 10 minutes under the same conditions as in step 1), and then carry out a hydrothermal synthesis reaction.

[0037] 5. The preparation method of the double-metal layered hydroxide according to 4, wherein M(II) is at least one of Mg and Zn; M(III) is Al; A n- is CO3 2- .

[0038] 6. The preparation method of the double-metal layered hydroxide according to 5, wherein carbon dioxide is introduced during the reaction.

[0039] 7. The preparation method of the double-metal layered hydroxide according to 5, wherein carbon dioxide is not introduced during the reaction.

[0040] 8. The preparation method of the double-metal layered hydroxide according to 4, wherein the molar ratio of M(II) to M(III) is 2M(II) / M(III) = 3.6 - 9.0.

[0041] 9. The preparation method of the double-metal layered hydroxide according to 4, wherein the temperature of the hydrothermal synthesis reaction is 140°C - 200°C.

[0042] 10. The preparation method of the double-metal layered hydroxide according to 4, wherein surface treatment is further carried out.

[0043] The method for preparing the bimetallic layered hydroxide described in 11.4, wherein the M(II) source is 4MgCO3. Mg(OH)2 4H2O.

[0044] Invention Technology Effects

[0045] The bimetallic layered hydroxide of the present invention has high purity, excellent thermal stability and dispersibility, and can be used as a heat-insulating agent for agricultural films, a heat stabilizer for polymer materials such as PVC, a catalyst carrier, and a soil and water treatment agent. Attached Figure Description

[0046] Figure 1 : XRD pattern of natural alkaline magnesium carbonate used in the examples.

[0047] Figure 2 : This is a 10,000x SEM image of the natural alkaline magnesium carbonate used in the examples before grinding.

[0048] Figure 3 : This is a particle size distribution diagram of the bimetallic layered hydroxide obtained in Example 1.

[0049] Figure 4 : XRD pattern of the bimetallic layered hydroxide obtained in Example 1.

[0050] Figure 5 : This is a particle size distribution diagram of the bimetallic layered hydroxide obtained in Example 3.

[0051] Figure 6 : This is a 20,000x SEM image of the bimetallic layered hydroxide obtained in Example 3.

[0052] Figure 7 : A 50,000x SEM image of the bimetallic layered hydroxide obtained in Example 7.

[0053] Figure 8 : This is a particle size distribution diagram of the bimetallic layered hydroxide obtained in Comparative Example 1.

[0054] Figure 9 : A 20,000x SEM image of the bimetallic layered hydroxide obtained in Comparative Example 1.

[0055] Figure 10 : XRD pattern of the bimetallic layered hydroxide obtained in Comparative Example 1.

[0056] Figure 11 : This is a 20,000x SEM image of the bimetallic layered hydroxide obtained in Example 2.

[0057] Figure 12 : Comparison of XRD patterns of bimetallic layered hydroxides obtained in Example 3 and Comparative Example 1.

[0058] Figure 13 : XRD pattern of the bimetallic layered hydroxide obtained in Comparative Example 4.

[0059] Figure 14 : Comparison of the XRD patterns of the bimetallic layered hydroxides obtained in Comparative Example 3 and Comparative Example 4.

[0060] Figure 15 : A graph showing the results of dynamic thermal stability tests.

[0061] Figure 16 : A graph showing a magnified comparison of the dynamic thermal stability of some embodiments and comparative examples.

[0062] Figure 17 : A graph showing a magnified comparison of the dispersion of some embodiments and comparative examples.

[0063] Figure 18 : A graph showing the comparison results of thermal stability in a reference application example. Detailed Implementation

[0064] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

[0065] According to the present invention, a bimetallic layered hydroxide and a method for preparing the same are provided. These will be described in detail below.

[0066] Bimetallic layered hydroxides

[0067] The bimetallic layered hydroxide of the present invention can be derived from the general formula [M(II)]. 1-x M(Ⅲ) x (OH)2] x+ (A n- ) x / n ·mH2O represents a compound where M(Ⅱ) contains at least one divalent cation selected from Mg, Zn, Ca, Ni, Co, Cu, Fe, Mn, and Sr, and M(Ⅲ) contains at least one trivalent cation selected from Al, Fe, Cr, Co, In, Ga, and V. n- Contains CO3 2- OH - F - Cl - SO4 2- NO3 - PO4 3- B(OH) - VO43- , MnO4 - , ClO4 - An anion of at least one of carboxylate, sulfonate, sulfinate, thio-carboxylate, where 0 < x < 1, n is the valence of A, and m is a number greater than or equal to 0.

[0068] The bimetallic layered hydroxide is typically particulate, with an average particle size D50 of 0.3 - 1.0 μm, a BET specific surface area of 8 - 25 m 2 / g, and a crystallite size of the D003 plane of 340 - 400 Å.

[0069] The bimetallic layered hydroxide of the present invention has excellent thermal stability and dispersibility due to its suitable physical properties such as particle size, specific surface area, and crystallite size.

[0070] The above M(II) includes at least one divalent cation selected from Mg, Zn, Ca, Ni, Co, Cu, Fe, Mn, Sr, preferably includes at least one of Mg and Zn, and more preferably is Mg.

[0071] The above M(III) includes at least one trivalent cation selected from Al, Fe, Cr, Co, In, Ga, V, and preferably includes Al.

[0072] A n- is an interlayer anion, including those selected from CO3 2- , OH - , F - , Cl - , SO4 2- , NO3 - , PO4 3- , B(OH) - , VO4 3- , MnO4 - , ClO4 - , carboxylate (R-COO - ), sulfonate (R-SO3 - ), sulfinate (R-SOO - ), thio-carboxylate (R-COS - ), and at least one well-known anion in the art, preferably including CO3 2- .

[0073] The average particle size D50 of the bimetallic layered hydroxide of the present invention is 0.3~1.0 μm. When the average particle size is less than 0.3 μm, the particles tend to agglomerate, affecting dispersibility. When the average particle size is greater than 1.0 μm, it will adversely affect thermal stability. This average particle size can be measured by laser diffraction scattering. The average particle size is preferably 0.3~0.9 μm, more preferably 0.3~0.8 μm, and even more preferably 0.3~0.6 μm.

[0074] The bimetallic layered hydroxide of the present invention has a BET specific surface area of ​​8-25 m². 2 / g. When the specific surface area of ​​BET is less than 8m² 2 At a concentration of / g, the energy required to prepare bimetallic layered hydroxides is too high, therefore it is not preferred. When the specific surface area of ​​BET is greater than 25m², ... 2 At a concentration of / g, the particle growth is insufficient and therefore not preferred. The BET specific surface area can be measured by nitrogen adsorption. The preferred BET specific surface area is 12~18m². 2 / g, more preferably 12~16m 2 / g, further preferably 12~14m 2 / g.

[0075] The crystallite size of the d003 facet of the bimetallic layered hydroxide of this invention is 340-400 angstroms. When the crystallite size is within this range, it indicates suitable grain growth, which can bring excellent plate-like structure to the bimetallic layered hydroxide, and easily obtain excellent thermal stability and dispersibility. If the crystallite size of the d003 facet is too small, it is not conducive to improving the dispersibility and performance of the product, not conducive to improving the purity of the product, and affects its anion exchange performance, etc. If the crystallite size is too large, it will also affect the dispersibility, thermal stability, and plate-like structure.

[0076] Furthermore, the interlayer distance of the d003 crystal face of the bimetallic layered hydroxide of the present invention deviates from the theoretical value 2 by the interlayer distance of the d006 crystal face within ±0.25%. By ensuring that the ratio of the interlayer distance of the d003 face to the interlayer distance of the d006 face deviates from the theoretical value 2 within ±0.25%, the bimetallic layered hydroxide of the present invention has a good plate shape and regular structure. When the above deviation exceeds 0.25%, it will lead to a decrease in dispersibility, thermal stability, etc. More preferably, this deviation is within ±0.2%, further preferably within ±0.1%, and most preferably 0%.

[0077] In addition to M(II) and M(III) mentioned above, without affecting the effectiveness of the invention, the bimetallic layered hydroxide of the present invention may also include other metal ions that can be used in bimetallic layered hydroxides, such as Li. + Ti4+ Sn 4+ and Zr 4+ And other interlayer anions, such as SiO3 2- Si2O5 2- Si3O7 2- Si4O9 2- (HSiO3) - (HSi2O5) - Silicon-containing anions, such as HPO4 2- PO4 3- and P2O7 4- Phosphorus-containing anions, etc.

[0078] The bimetallic layered hydroxide of the present invention can also be surface-treated using known compounds such as higher fatty acids, alkaline earth metal salts of higher fatty acids, surfactants, coupling agents, and phosphate esters of phosphoric acid and higher alcohols.

[0079] The bimetallic layered hydroxide of the present invention exhibits excellent dispersibility and thermal stability when used as a heat stabilizer for PVC, due to its suitable particle size, specific surface area, crystallite size and other physical properties, as well as its excellent plate structure.

[0080] Preparation method of bimetallic layered hydroxides

[0081] The present invention also provides a method for preparing the above-mentioned bimetallic layered hydroxide, comprising: 1) grinding the M(II) source to an average particle size D50≤2.5μm and grinding the M(III) source to an average particle size D50≤2.5μm; 2) mixing the above-ground raw materials and grinding them for more than 10 minutes under the same conditions as in step 1), and then carrying out a hydrothermal synthesis reaction.

[0082] In the preparation method of the present invention, the M(II) source can be a metal compound containing M(II), such as its oxide, hydroxide, or carbonate; more specifically, it is a compound of at least one metal selected from Mg, Zn, Ca, Ni, Co, Cu, Fe, Mn, and Sr, such as its oxide, hydroxide, or carbonate; preferably an oxide, hydroxide, or carbonate of Mg and / or Zn; more preferably, basic magnesium carbonate. Specifically, magnesium oxide, zinc oxide, magnesium hydroxide, basic magnesium carbonate, etc., can be listed. These metal compounds can be obtained in a manner known in the art, for example, commercially available. The M(II) source can be used alone or in combination of two or more raw materials. Furthermore, the M(II) source can be a lightly calcined product sintered below 1000°C.

[0083] The M(III) source can be a metal compound containing M(III), such as its oxide, hydroxide, or carbonate; more specifically, it is a metal compound selected from at least one of Al, Fe, Cr, Co, In, Ga, and V, such as its oxide, hydroxide, or carbonate; preferably, it is an Al compound. Specifically, examples include aluminum hydroxide, alumina, boehmite, amorphous aluminum hydroxide, gibbsite, Bayerite, aluminum carbonate, and basic aluminum carbonate. Alumina can be in any form of η-Al₂O₃, β-Al₂O₃, or γ-Al₂O₃. The Al source can be crystalline or amorphous. These metal compounds can be obtained in a manner known in the art, for example, commercially available. The M(III) source can be used alone or in combination of two or more sources.

[0084] By A n- The anion source can originate from anions contained within the M(II) source and / or M(III) source itself, or it can be introduced during the reaction. Preferably, the anion source is introduced through anions contained within the M(II) source and / or M(III) source itself. This simplifies the reaction and equipment, avoids the introduction of other undesirable impurities, and eliminates the need for cumbersome cleaning to remove impurities. For example, in A... n- CO3 2- In this case, CO3 can originate from carbonate compounds that serve as M(II) and / or M(III) sources, or it can be introduced into the system by introducing carbon dioxide gas during the reaction. Preferably, CO3 is introduced using carbonate ions contained within the M(II) and / or M(III) sources themselves. 2- This avoids introducing carbon dioxide gas. Other anion sources can be obtained, for example, through ion exchange using compounds containing the corresponding anions, such as inorganic or organic acids.

[0085] In step 1) of the preparation method of the present invention, the M(II) source and the M(III) source need to be ground to an average particle size D50 ≤ 2.5 μm, preferably to D50 ≤ 2.0 μm, and more preferably to D50 ≤ 1.5 μm (hereinafter, step 1) is sometimes referred to as pre-grinding). If the average particle size exceeds 2.5 μm, the activity of the M(II) source and the M(III) source may be insufficient, and the expected bimetallic layered hydroxide of the present invention cannot be generated. The grinding is preferably wet grinding, during which the M(II) source and the M(III) source are ground separately. The pre-grinding is performed on at least 50 wt% of each of the M(II) source and the M(III) source, preferably on at least 60 wt% of each, more preferably on at least 80 wt% of each, and even more preferably on all of the M(II) source and the M(III) source.

[0086] The grinding can be carried out at an initial temperature of 0°C to 50°C, preferably 10°C to 40°C, and at a rotation speed of 2500 to 3500 rpm, preferably 2800 to 3200 rpm. Grinding (pre-grinding) under these conditions can fully disperse the material and improve its activity.

[0087] Further, in step 2) of the preparation method of the present invention, the ground M(II) source and M(III) source are mixed at the molar ratio required for the target bimetallic layered hydroxide, and then ground for at least 10 minutes under the same conditions as in step 1), followed by a hydrothermal reaction. In the present invention, "the same conditions" refers to the same starting temperature and the same rotation speed. The lower limit of the grinding time is at least 10 minutes, preferably at least 20 minutes. On the other hand, although there is no upper limit to the grinding time, according to one approach, it is usually less than 60 minutes from the viewpoint of manufacturing efficiency, etc. According to another approach, the upper limit of the grinding time is, for example, less than 50 minutes, preferably less than 30 minutes. By continuing grinding for at least 10 minutes under the same conditions as in step 1), the reactants can be further thoroughly mixed and activated, and the reactants can undergo a preliminary reaction. Through this secondary grinding step, the bimetallic layered hydroxide with the excellent plate structure described above can be obtained. Through this secondary grinding step, when an anion source is introduced through the anions contained in the M(II) source and / or the M(III) source itself, the reaction activity can be promoted. Furthermore, in the hydrothermal reaction, it is preferable to control the concentration of the product below 90 g / L, and more preferably below 70 g / L. This is because if the solid content of the product is too high, insufficient stirring and dispersion will lead to increased aggregation of the product and poor product dispersion.

[0088] In the preparation method of the present invention, the molar ratio of M(II) source to M(III) source can be controlled at 2M(II) / M(III) = 3.6~9.0, preferably 4.0~5.0. If the molar ratio exceeds 9.0, it may lead to the precipitation of M(II) source; if it is below 3.6, it may lead to the precipitation of M(III) source.

[0089] In the above hydrothermal reaction process, the reactor can be heated to the required temperature at a certain rate while stirring. After several hours of constant temperature treatment, the product is filtered, washed with a small amount of water, dried, and pulverized to obtain the desired product. The water used for washing can be reused in subsequent grinding.

[0090] For the heating conditions of this reaction, the temperature can be between 140℃ and 200℃ in a sealed environment. Temperatures below 140℃ will result in excessively long reaction times and low production efficiency. Preferably, the temperature is between 160℃ and 180℃, within which heating time is short, production efficiency is high, and product dispersibility is good. The heating treatment time is between 2 and 12 hours, preferably 4 to 6 hours.

[0091] Since the wastewater generated by the preparation method of the present invention does not contain salts as in traditional methods, the water utilization rate is greatly improved, the water washing volume is less than 1 / 15 of that of traditional methods, and the cost is reduced.

[0092] The bimetallic layered hydroxide of the present invention can be surface-treated according to its intended use. The surface treatment agent can be a known compound. Specifically, as a surface treatment agent, higher fatty acids, alkaline earth metal salts of higher fatty acids, surfactants, coupling agents, and phosphate esters of phosphoric acid and higher alcohols can be used.

[0093] The surface treatment method can be either a known wet or dry method. In the wet method, the amount of surface treatment agent added is 0.01 to 10 parts by weight, preferably 0.05 to 8 parts by weight, relative to 100 parts by weight of the bimetallic layered hydroxide particles. The surface treatment temperature is 50 to 95°C. In the dry method, for example, the above-mentioned amount of surface treatment agent can be dispersed in an organic solvent, thoroughly mixed with the bimetallic layered hydroxide particles, and the organic solvent can be evaporated at 120°C under high-speed stirring.

[0094] The bimetallic layered hydroxide of the present invention can be obtained through the above preparation method. The bimetallic layered hydroxide of the present invention exhibits excellent thermal stability, dispersibility, and high purity. It can be used as a heat-insulating agent for agricultural films, a heat stabilizer for polymer materials such as PVC, a catalyst carrier, and a soil and water treatment agent.

[0095] Example

[0096] The present invention will be described in more detail below with reference to the embodiments, but the present invention is not limited to any of the embodiments described below.

[0097] The test methods used in the examples and comparative examples are described below.

[0098] Test methods

[0099] Scanning electron microscopy (SEM) testing

[0100] The dried sample particles were photographed using a field emission scanning electron microscope (FE-SEM, trade name: JSM-7600F) manufactured by Nippon Electron Ltd.

[0101] X-ray diffraction (XRD) test

[0102] The sample powder was placed on an XRD test stage and the sample surface was planarized to obtain the test sample. An EMPYREAN sample prepared using PANalytical BV was used for testing, and the X-ray diffraction pattern was obtained and read. 003 face and d 006 The interlayer distance of the surface. Also, regarding d... 003 and d 006The relationship, theoretically, is based on the interval d. 003 =2d 006。 The closer the two values ​​are to 2, the more regular the layer structure of the product. Specific test conditions are as follows:

[0103] X-ray source: Cu-Kα rays (λ=1.542Å)

[0104] Voltage / Current: 45kV / 40mA

[0105] Goniometer: Horizontal goniometer for sample (reflection mode)

[0106] Step angle: 0.013°

[0107] Scanning speed: 9.8° / min

[0108] Diffraction angle 2θ: 5~70°

[0109] Particle size test

[0110] Particle size was determined using a laser diffraction scattering particle size analyzer (model MT-3300EX-Ⅱ) manufactured by Nippon Seiki Co., Ltd.

[0111] Measurement conditions: 80 ml of a 0.2 wt% sodium hexametaphosphate aqueous solution was placed in a 100 ml glass beaker. 0.8 g of dried sample powder was added, and the mixture was ultrasonically treated for 3 minutes using a NISSEI "MODEL US-300" at a current of 400 μA. Then, 2-4 ml of the resulting dispersion was added to the sample chamber of the particle size analyzer, which had been filled with 220 ml of degassed sodium hexametaphosphate aqueous solution (2.0 g / L) and circulated. After circulating the dispersion for 1 minute, the particle size distribution was measured.

[0112] BET specific surface area test

[0113] The measurements were performed using a high-precision gas adsorption capacity measuring device (BELsoro-max from Macchique Bayer Co., Ltd.). Specifically, a constant-volume gas adsorption method using nitrogen was employed, and the specific surface area was calculated using the BET multi-point method.

[0114] Composition Quantitative Testing

[0115] <Acid Dissolution Method>

[0116] Place 0.5g of sample in a 100ml beaker, add 10ml of dilute hydrochloric acid and 5ml of perchloric acid, and heat on a hot plate to dissolve. Transfer the sample solution from the beaker to a 250ml volumetric flask and dilute to 250ml. Using this diluted sample solution, determine the contents of MgO and Al2O3 according to the following methods.

[0117] (1) Quantitative analysis of Mg

[0118] Pipette 10 ml of the above sample solution into a 200 ml beaker and dilute to 100 ml with deionized water. Add 5 ml of triethanolamine aqueous solution to the diluted sample solution and use a pH meter to add ammonium chloride-ammonia buffer solution until pH = 10. Add 15 drops of universal BT indicator and titrate with 0.01 mol / L EDTA standard solution.

[0119] (2) Quantitative analysis of Al2O3

[0120] Pipette 10 ml of the above sample solution into a 200 ml beaker, and add 30 ml of 0.01 mol / L CyDTA standard solution using a pipette. Further add hexamethylenetetramine to bring the pH to 5.0–5.5 as measured by a pH meter. Add 3 drops of XO indicator and titrate with 0.01 mol / L zinc acetate standard solution. Using the quantified Mg and Al₂O₃ contents, calculate the Mg / Al₂ molar ratio.

[0121] <Quantitative Analysis of CO2>

[0122] Add 30 ml of 0.1 mol / L NaOH standard solution and 30 ml of 10 wt% BaCl2 solution to an absorption flask, and adjust the volume to 300 ml with pure water.

[0123] Add 0.3 g of sample to a dissolving flask, dilute to 50 ml with CO2-free purified water, and add 2 drops of methyl orange indicator. Seal the two containers and pour 1 mol / L HCl into the dissolving flask until it reaches 100 ml. Heat to boiling on a hot plate for 10 minutes. Then titrate the solution in the absorption flask with 0.1 mol / L HCl standard solution to determine CO3²⁻. - content.

[0124] Dynamic thermal stability and dispersibility test

[0125] i) Formula

[0126] The formulation used in the evaluation of dynamic thermal stability is:

[0127] TK-1300: PVC linear polymer from Shin-Etsu Co., Ltd., Japan, 100 phr; DINP: diisononyl phthalate, 50 phr; Zn-St: zinc stearate, 0.6 phr; Example and comparative sample: 3.0 phr.

[0128] ii) First, the evaluation materials are mixed. The specific steps are as follows:

[0129] Feed the material into the roller press (roller press: 170℃);

[0130] The falling material is fed into the roller press;

[0131] Repeat the previous step until the material is plasticized;

[0132] After the material is plasticized, it is wound onto a roller press;

[0133] Cut off the left and right ends of the roll-formed sheet and confirm and adjust the thickness;

[0134] Repeat the operation several times;

[0135] Five minutes after the mixing begins, the sheets are cut and cooled.

[0136] iii) Dynamic thermal stability Dispersion evaluation

[0137] Test method:

[0138] Three sheets matching the forming mold were cut from the roll-formed sheet, stacked, and then pressurized and measured. The forming and measurement conditions are as follows:

[0139] Pressure molding conditions

[0140] Equipment: Compression molding machine ANSF-50HH / C (without preheating)

[0141] Mold: 25mm×75mm×2mm

[0142] Temperature: 190℃

[0143] Pressure (heating): 0~1.0 min: 0.5 MPa; 1.0~5.0 min: 1.0 MPa, with the pressure increasing to 3.0 MPa in the last 10 seconds and cooling at this pressure.

[0144] The criteria for judging dynamic thermal stability are as follows.

[0145] ◎: The color of the test piece remained basically unchanged after 30 minutes (visual inspection);

[0146] ○: Slight discoloration after 30 minutes (visual inspection);

[0147] △: The color of the test piece changed significantly after 30 minutes (visual inspection).

[0148] The evaluation criteria for dispersion are as follows.

[0149] ◎: No dispersed particles were observed in the test piece (visual inspection);

[0150] △: A small amount of undispersed particles were observed (visual inspection);

[0151] ×: A large number of undispersed particles were observed (visual inspection).

[0152] Congo Red Test

[0153] Cut 2g of 5mm square test pieces from the sheet after mixing in the roller press and place them in a test tube. Insert glycerin-moistened Congo red test paper into a slit cork, adjusting the length so that the bottom of the Congo red test paper is 4cm from the mouth of the test tube, and then stopper the tube. Place the test tube prepared as described above in an oil bath at 200°C and measure the time until the Congo red test paper turns blue.

[0154] Resistance test

[0155] Resistance testing was performed using a Mitsubishi MCP-HT450 from Japan on the sheet material after mixing by the aforementioned roller press, which measures 10cm × 10cm × 0.1cm.

[0156] Microcrystal size testing

[0157] The crystallite size D was determined using the Scherrer formula. hkl .

[0158] Scherrer type D hkl =[0.9×λ / βcosθ]×180 / π=79.46Å / βcosθ

[0159] λ = wavelength of the X-rays used; β = full width at half maximum (FWHM); θ = Bragg angle (half of 2θ)

[0160] [Pre-grinding process]

[0161] In the preliminary grinding process, the raw materials used in the examples are ground. The specific grinding equipment, main raw materials and grinding process are as follows.

[0162] Grinding equipment: Pailer PHN-0.5CE sand mill, 3000 rpm

[0163] Magnesium raw materials:

[0164] Natural alkaline magnesium carbonate [4MgCO3] Mg(OH)2 [4H2O]: Produced by Tibet Dade Materials Technology Co., Ltd., with the following content as calculated MgO: 41.42 wt%; Fe (ppm): 114; Al2O3 (wt%): 0.07; Mn (ppm): 3.5; SiO2 (ppm): 201. Its XRD pattern and 10,000x SEM image can be found in [reference needed]. Figure 1 and Figure 2 .

[0165] MgO: Produced by Qinghai Western Magnesium Industry Co., Ltd., content (wt%): 99.01; D50 (μm): 58; drying loss (wt%): 0.3; Fe (ppm): 1; CaO (wt%): 0.001; SiO2 (wt%): 0.001.

[0166] Aluminum raw materials:

[0167] Al(OH)3: Produced by Shandong Lubei Haisheng Biotechnology Co., Ltd., content (wt%): 96; D50 (μm): 95.2; Fe (ppm): 1.5.

[0168] Boehmite AlOOH: Produced by Zibo Jiulong Chemical Technology Co., Ltd., content (wt%): 95; D50 (μm): 30; Fe (ppm): 5.

[0169] Grinding conditions in the pre-grinding process

[0170] MgO: 200 g / L (4.962 mol / L)

[0171] 1000g of magnesium oxide was dispersed in water and the volume was adjusted to 5L. The mixture was then ground for 20 minutes at room temperature. The particle size (D50) after grinding was 2.4μm.

[0172] Al(OH)3: 100g / L (1.2819mol / L)

[0173] Disperse 500g of aluminum hydroxide in water to a volume of 5L, then grind for 60 minutes at room temperature. The particle size (D50) after grinding is 1.5μm.

[0174] AlOOH: 100g / L (1.6667mol / L)

[0175] Disperse 500g of boehmite in water to a volume of 5L, then grind for 60 minutes at room temperature. The particle size (D50) after grinding is 1.5μm.

[0176] [4MgCO3 Mg(OH)2 [4H2O]: 150 g / L (calculated as MgO, 1.5413 mol / L)

[0177] Disperse 750g of natural alkaline magnesium carbonate in water to a volume of 5L, then grind for 30 minutes at room temperature. The particle size (D50) after grinding is 2.0μm.

[0178] [Example 1] Mg 4.3 Al2(OH) 12.6 Synthesis of CO3 (M = 432.83):

[0179] 0.26[4MgCO3 Mg(OH)2 4H2O]+3MgO+2Al(OH)3+2.04H2O=Mg 4.3 Al2(OH) 12.6 CO3 + 0.04H2CO3

[0180] Take 205.66 ml of pre-ground MgO slurry (containing 1.0205 mol of MgO) and 530.52 ml of pre-ground Al(OH)3 slurry (containing 0.68 mol of Al(OH)3), mix them, and then add 286.45 ml of pre-ground natural alkaline magnesium carbonate slurry (containing 41.42 wt% magnesium oxide, equivalent to 0.4415 mol of MgO). Grind and disperse the mixture for 20 minutes under the same conditions as the pre-ground mixture, then transfer it to a 3.0 L high-pressure reactor and adjust the volume to 2.1 L with deionized water. Heat the mixture at 170 °C for 4 hours with continuous stirring (product concentration approximately 70 g / L). After cooling the slurry to 80–85 °C, slowly add an aqueous solution containing 2.95 g of sodium stearate at 80–85 °C (surface treatment amount 2.0 wt%) with stirring, and continue stirring for 30 minutes. Solid-liquid separation was then performed using a Nutsche filter. The resulting solid was washed with 150 ml of deionized water and dried at 105°C for 12 hours. The dried material was then pulverized using a hammer mill and sieved through a 150-micron filter. The resulting powder was designated as the sample for Example 1.

[0181] Testing revealed that the powder had a D50 of 0.60 μm and a BET specific surface area of ​​13 m² / g. Based on the quantitative compositional analysis, the final chemical composition of the powder was determined to be Mg. 4.3 Al2(OH) 12.6 •CO3. Its particle size distribution and XRD pattern can be found in... Figure 3 and Figure 4 Other test results are shown in Table 1 and... Figure 15 .

[0182] [Example 2] Mg 4.05 Al2(OH) 12.1 Synthesis of CO3 (M = 418.25):

[0183] 0.54[4MgCO3 Mg(OH)2 4H2O]+1.35MgO+2Al(OH)3+1.51H2O=Mg 4.05 Al2(OH) 12.1 CO3 + 1.16H2CO3

[0184] Take 95.73 ml of pre-ground MgO slurry (containing 0.475 mol MgO) and 548.45 ml of pre-ground Al(OH)3 slurry (containing 0.703 mol Al(OH)3), mix them, and then add 616.87 ml of pre-ground natural alkaline magnesium carbonate slurry (41.42 wt% magnesium oxide, equivalent to 0.9506 mol MgO). Under the same conditions as pre-ground slurry, grind and disperse for 20 minutes, then transfer to a 3.0 L high-pressure reactor and adjust the volume to 2.1 L with deionized water. Heat at 165 °C for 4 hours with continuous stirring (product concentration approximately 70 g / L). After cooling the slurry to 80–85 °C, slowly add an aqueous solution containing 2.95 g sodium stearate at 80–85 °C with stirring, and continue stirring for 30 minutes. Then, perform solid-liquid separation through a Nutsche filter. Wash the obtained solid with 150 ml of deionized water and dry at 105 °C for 12 hours. The dried material was pulverized using a hammer mill and then sieved through a 150-micron filter. The resulting powder was recorded as the sample of Example 2.

[0185] Testing revealed that the powder had a D50 of 0.50 μm and a BET specific surface area of ​​14 m² / g. Based on the quantitative compositional analysis, the final chemical composition of the powder was determined to be Mg. 4.05 Al2(OH) 12.1 CO3. Its 20,000x SEM image can be found in... Figure 11 Other test results are shown in Table 1 and... Figure 15 .

[0186] [Example 3] Mg 4.05 Al2(OH) 12.1 Synthesis of CO3 (M = 418.25):

[0187] 0.81[4MgCO3 Mg(OH)2 4H₂O]+2Al(OH)₃+1.24H₂O=Mg 4.05 Al2(OH) 12.1 CO3 + 2.24H2CO3

[0188] Take 853.99 ml of pre-ground natural alkaline magnesium carbonate slurry (containing 1.3163 mol MgO) and 507.06 ml of pre-ground Al(OH)3 slurry (containing 0.65 mol Al(OH)3), mix them, and then grind and disperse them for 20 minutes under the same conditions as the pre-grinding process. Transfer the mixture to a 3.0 L high-pressure reactor and adjust the volume to 2.1 L with deionized water. Heat the mixture at 170 °C for 6 hours with continuous stirring (product concentration approximately 65 g / L). After cooling the slurry to 80-85 °C, slowly add an aqueous solution containing 2.95 g sodium stearate at 80-85 °C with stirring, and continue stirring for 30 minutes. Then, perform solid-liquid separation through a Nutsche filter. Wash the obtained solid with 150 ml of deionized water and dry at 105 °C for 12 hours. Crush the dried material using a hammer mill and sieve it through a 150-micron filter. The resulting powder is designated as the sample of Example 3.

[0189] Testing revealed that the powder had a D50 of 0.60 μm and a BET specific surface area of ​​13 m² / g. Based on the quantitative compositional analysis, the final chemical composition of the powder was determined to be Mg. 4.05 Al2(OH) 12.1 •CO3. Its particle size distribution map and 20,000x SEM image can be found in... Figure 5 and Figure 6 Other test results are shown in Table 1 and... Figure 15 .

[0190] [Example 4] Mg 4.1 Al2(OH) 12.2 Synthesis of CO3 (M = 421.16):

[0191] 1.1MgCO3+3MgO+2Al(OH)3+3.2H2O=Mg 4.1 Al2(OH) 12.2 CO3 + 0.1H2CO3

[0192] Take 211.61 ml of pre-ground MgO slurry (containing 1.05 mol of MgO) and 546.06 ml of pre-ground Al(OH)3 slurry (containing 0.70 mol of Al(OH)3), mix them, and then add 0.385 mol of commercially available magnesium carbonate (32.46 g, Shanghai Yuanye Biotechnology Co., Ltd., D50 = 10 μm). Under the same conditions as pre-ground slurry, grind and disperse for 20 minutes, then transfer to a 3.0 L high-pressure reactor and adjust the volume to 2.1 L with deionized water. Heat the mixture at 170 °C for 6 hours with continuous stirring (product concentration approximately 70 g / L). After cooling the slurry to 80–85 °C, slowly add an aqueous solution containing 2.95 g of sodium stearate at 80–85 °C with stirring, and continue stirring for 30 minutes. Then, perform solid-liquid separation through a Nutsche filter. Wash the obtained solid with 150 ml of deionized water and dry at 105 °C for 12 hours. The dried material was pulverized using a hammer mill and then sieved through a 150-micron filter. The resulting powder was recorded as the sample of Example 4.

[0193] Testing revealed that the powder had a D50 of 0.40 μm and a BET specific surface area of ​​14 m² / g. Based on the quantitative compositional analysis, the final chemical composition of the powder was determined to be Mg. 4.05 Al2(OH) 12.1 • CO3. Other test results are shown in Table 1 and Figure 15 .

[0194] [Example 5] Mg5Al2(OH) 14 Synthesis of CO3 (M=473.66):

[0195] 5MgO+2Al(OH)3+CO2↑+4H2O=Mg5Al2(OH) 14 CO3

[0196] Take 312.37 ml of pre-ground MgO slurry (containing 1.55 mol MgO) and 483.66 ml of pre-ground Al(OH)3 slurry (containing 0.62 mol Al(OH)3), mix them, and adjust the volume to 2.1 L with deionized water. After grinding and dispersing under the same conditions as pre-grinding for 20 minutes, transfer the mixture to a 3.0 L high-pressure reactor. Introduce commercially available carbon dioxide (CO2) gas into the reactor with continuous stirring, injecting 6.95 L of CO2 (0.31 mol) over 60 minutes. Then, raise the temperature to 170 °C for 1 hour and maintain this temperature at 170 °C for 6 hours (product concentration approximately 70 g / L). After cooling the slurry to 80–85 °C, slowly add an aqueous solution containing 2.95 g sodium stearate at 80–85 °C with stirring, and continue stirring for 30 minutes. Solid-liquid separation was then performed using a Nutsche filter. The resulting solid was washed with 150 ml of deionized water and dried at 105°C for 12 hours. The dried material was then pulverized using a hammer mill and sieved through a 150-micron filter. The resulting powder was designated as the sample for Example 5.

[0197] Testing revealed that the powder had a D50 of 0.60 μm and a BET specific surface area of ​​13 m² / g. Based on the quantitative compositional analysis, the chemical composition of the powder was ultimately determined to be Mg₅Al₂(OH). 14 • CO3. Other test results are shown in Table 1 and Figure 15 .

[0198] [Example 6] Mg 3.3 Zn 1.0 Al2(OH) 12.6 Synthesis of CO3 (M=473.52):

[0199] 3.3MgO+ZnO+2Al(OH)3+CO2↑+4H2O=Mg 3.3 Zn 1.0 Al2(OH) 12.6 CO3

[0200] Take 206.17 ml of pre-ground MgO slurry (containing 1.023 mol of MgO) and 481.0 ml of pre-ground Al(OH)3 slurry (containing 0.62 mol of Al(OH)3). Disperse 0.30 mol of commercially available nano ZnO (24.6 g, manufactured by Bohuas Nanotechnology (Ningbo) Co., Ltd., 99.9%, particle size 50 nm) in 500 ml of water. Mix the three materials and adjust the volume to 2.1 L with deionized water. After grinding and dispersing for 20 minutes under the same conditions as pre-grinding, transfer the mixture to a 3.0 L high-pressure reactor. Introduce commercially available carbon dioxide gas (CO2) into the reactor with continuous stirring, injecting 7.0 L of carbon dioxide gas (CO2, 0.31 mol) over 70 minutes. Then raise the temperature to 140 °C for 1 hour and maintain the temperature at 140 °C for 4 hours (product concentration approximately 70 g / L). After cooling the slurry to 80-85°C, an aqueous solution containing 2.95g of sodium stearate at 80-85°C was slowly added while stirring, and the mixture was stirred continuously for 30 minutes. Subsequently, solid-liquid separation was performed using a Nutsche filter. The resulting solid was washed with 150ml of deionized water and dried at 105°C for 12 hours. The dried material was then pulverized using a hammer mill and sieved through a 150-micron screen. The resulting powder was designated as the sample of Example 6.

[0201] Testing revealed that the powder had a D50 of 0.40 μm and a BET specific surface area of ​​16 m² / g. Based on the quantitative compositional analysis, the final chemical composition of the powder was determined to be Mg. 3.3 ZnAl2(OH) 12.6 • CO3. Other test results are shown in Table 1 and Figure 15 .

[0202] [Example 7] Mg5Al2(OH) 14 Synthesis of CO3 (M=473.66):

[0203] 5MgO+2AlOOH+CO2↑+6H2O=Mg5Al2(OH) 14 CO3

[0204] Except for replacing the Al(OH)3 raw material in Example 5 with an equimolar proportion of pre-ground AlOOH, the other processing conditions were the same as in Example 5. After washing, drying, and pulverizing, the resulting powder was designated as the sample of Example 7.

[0205] Testing revealed that the powder had a D50 of 0.50 μm and a BET specific surface area of ​​15 m² / g. Based on the quantitative compositional analysis, the chemical composition of the powder was ultimately determined to be Mg₅Al₂(OH). 14 CO3. Its 50,000x SEM image can be found in... Figure 7 Other test results are shown in Table 1 and... Figure 15 .

[0206] [Comparative Example 1] (Refer to Example 2 of CN101516781A)

[0207] 0.076 [4MgCO3] Mg(OH)2 5H2O]+0.88MgO+0.62Al(OH)3+0.5H2O→Mg 1.26 Al 0.62 (OH) 3.772 (CO3) 0.304 =Mg 4.06 Al2(OH) 12.168 (CO3) 0.98

[0208] Disperse 37.7g of 4MgCO3 in 1378g of deionized water. Mg(OH)2 5H₂O, 35.5g MgO, and 48.4g aluminum hydroxide (ATH) were ground until the average particle size reached 2.5~3.0μm. The ground slurry was transferred to a 2L high-pressure reactor and heated at 170°C for 1 hour. After cooling the slurry to 80~85°C, sodium stearate aqueous solution (2% surface treatment amount) was slowly added under stirring, and the stirring was continued for 30 minutes. After filtration, washing, and drying, the resulting product was designated as Comparative Example 1. Its chemical composition was determined to be Mg. 4.06 Al2(OH) 12.168 (CO3) 0.98 Its particle size distribution map, 20,000x SEM image, and XRD pattern can be found in [reference needed]. Figure 8 , Figure 9 as well as Figure 10 A comparison of the XRD patterns of the bimetallic layered hydroxides obtained in Example 3 and Comparative Example 1 is shown below. Figure 12 Other test results are shown in Table 1 and... Figure 15 .

[0209] [Comparative Example 2] (Refer to Example 1 of CN103108907B)

[0210] 0.903MgO+0.42Al(OH)3+0.693H2O+0.21CO2↑→Mg 0.903 Al 0.42 (OH) 2.646 (CO3) 0.21 =Mg 4.30 Al2(OH)12.6 CO3 (M=432.83)

[0211] 0.903 mol of magnesium oxide and 0.42 mol of aluminum hydroxide were added to 2 L of deionized water. After grinding at 3000 rpm for 1 hour, the slurry was transferred to a 3 L high-pressure reactor. After sealing, 0.21 mol of carbon dioxide gas was injected, and the reactor was heat-treated at 170°C for 6 hours. After cooling the slurry to 80-85°C, an aqueous solution of sodium stearate (2% surface treatment amount) at 80-85°C was slowly added with stirring, and the mixture was stirred continuously for 30 minutes. After filtration, washing, and drying, the resulting product was designated as Comparative Example 2.

[0212] Although the raw material may be completely transformed into hydrotalcite particles under high temperature, high pressure, and prolonged heating conditions, the lack of pre-grinding severely affects the material's properties. Testing revealed its chemical composition to be Mg. 4.30 Al2(OH) 12.6 CO3. Other test results are shown in Table 1 and... Figure 15 .

[0213] [Comparative Example 3]

[0214] 1.0202 mol of MgO (41.13 g), 0.68 mol of Al(OH)3 (53.05 g), and 43 g of natural basic magnesium carbonate (containing 0.4415 mol of MgO) were added to a 2.1 L volume with water. The mixture was ground at 3000 rpm for 1.5 hours, then transferred to a 3 L high-pressure reactor for heat treatment. The remaining treatment conditions were the same as in Example 1. The test results are shown in Table 1.

[0215] [Comparative Example 4]

[0216] 0.475 mol of MgO (19.5 g), 0.703 mol of Al(OH)3 (54.84 g), and 92.51 g of natural basic magnesium carbonate (containing 0.9506 mol of MgO) were added to a 2.1 L volume with water. The mixture was ground at 3000 rpm for 1.5 hours, then transferred to a 3 L high-pressure reactor for heat treatment. The remaining treatment conditions were the same as in Example 2. The XRD pattern is shown in [reference needed]. Figure 13 A comparison of the XRD patterns of the bimetallic layered hydroxides obtained in Comparative Example 3 and Comparative Example 4 is shown in the figure. Figure 14 The test results are shown in Table 1.

[0217] Comparative Examples 3 and 4, which involved mixing three raw materials, grinding them for 1.5 hours, and then heating them directly (without pre-grinding), showed poorer uniformity in the reaction system compared to Examples 1 and 2. Under the same processing conditions, the product contained unreacted raw materials.

[0218] In addition, the stability and dispersibility of Examples 1 and 7 and Comparative Examples 1-2 are compared as follows: Figure 16 and 17 .from Figure 16 It can be seen that, in the color change at 30 minutes and 60 minutes, the comparative example showed a more significant color change compared to the example. From... Figure 17 It can be seen that, compared with Examples 1 and 7, Comparative Examples 1-2 have poor dispersibility.

[0219] Table 1A: Comparison of physical properties between the examples and comparative examples

[0220]

[0221] ↑: Indicates that it is the same as the previous column.

[0222] Table 1B: Comparison of physical properties between the examples and comparative examples

[0223]

[0224] [Example Application]

[0225] The performance of the sample prepared in Example 1 above was compared with that of the heat stabilizers Magcela-1 and Alkamaiza-1 prepared by Kyowa Chemical Industry Co., Ltd. using conventional processes. Thermal stability was tested according to the methods described in the "Dynamic Thermal Stability and Dispersibility Test" section above and the formulations in Table 2 "Sample Composition for Evaluation" below. The comparison results are shown below. Figure 18 (From left to right: Magsera-1, Alkamaize-1, Example 1). Magsera-1 and Alkamaize-1 are hydrotalcite used as a PVC stabilizer.

[0226] Table 2: Composition of the test samples used for evaluation

[0227]

[0228] As can be seen from the table and figures above, the dynamic thermal stabilization effect of the bimetallic layered hydroxide of the present invention is also superior to that of conventionally prepared thermal stabilizers.

[0229] Industrial availability

[0230] The bimetallic layered hydroxide of the present invention has excellent stability and dispersibility, and can be used as a heat-insulating agent for agricultural films, a heat stabilizer for polymer materials such as PVC, a catalyst carrier, and a soil and water treatment agent, with broad application prospects.

Claims

1. A bimetallic layered hydroxide, which is composed of formula [M(II)] 1-x M(Ⅲ) x (OH)2] x+ (A n- ) x / n ·mH2O means, where M(II) contains divalent cations selected from at least one of Mg, Zn, Ca, Ni, Co, Cu, Fe, Mn, Sr, M(III) contains trivalent cations selected from at least one of Al, Fe, Cr, Co, In, Ga, V, A n- Contains CO3 2- OH - F - Cl - SO4 2- NO3 - PO4 3- B(OH) - VO4 3- MnO4 - ClO4 - Anion of at least one of carboxylate, sulfonate, sulfinate, and thiocarboxylate. x is 0 < x < 1, n is the valence of A, and m is a number greater than or equal to 0, The average particle size D50 of this bimetallic layered hydroxide is 0.3–1.0 μm, and the BET specific surface area is 8–25 m². 2 / g, the crystallite size of the d003 plane is 340~400 angstroms.

2. The bimetallic layered hydroxide according to claim 1, wherein, the deviation of the ratio of the interlayer distance of the d003 plane to the interlayer distance of the d006 plane from the theoretical value of 2 is within the range of ±0.25%.

3. The bimetallic layered hydroxide according to claim 1, wherein, M(Ⅱ) is at least one of Mg and Zn; M(Ⅲ) is Al; A n- CO3 2- .

4. A method for preparing a bimetallic layered hydroxide, wherein the bimetallic layered hydroxide is derived from formula [M(II)]. 1-x M(Ⅲ) x (OH)2] x+ (A n- ) x / n ·mH2O means, where M(II) contains divalent cations selected from at least one of Mg, Zn, Ca, Ni, Co, Cu, Fe, Mn, Sr, M(III) contains trivalent cations selected from at least one of Al, Fe, Cr, Co, In, Ga, V, A n- Contains CO3 2- OH - F - Cl - SO4 2- NO3 - PO4 3- B(OH) - VO4 3- MnO4 - ClO4 - Anion of at least one of carboxylate, sulfonate, sulfinate, and thiocarboxylate. x is 0 < x < 1, n is the valence of A, and m is a number greater than or equal to 0, The preparation method includes: 1) Grinding the M(II) source to an average particle size D50 ≤ 2.5 μm and grinding the M(III) source to an average particle size D50 ≤ 2.5 μm; 2) Mixing the above-ground raw materials and continuing to grind for more than 10 minutes under the same conditions as in step 1), and then carrying out a hydrothermal synthesis reaction.

5. The method for preparing the bimetallic layered hydroxide according to claim 4, wherein, M(Ⅱ) is at least one of Mg and Zn; M(Ⅲ) is Al; A n- CO3 2- .

6. The method for preparing the bimetallic layered hydroxide according to claim 5, wherein, Carbon dioxide is introduced during the reaction.

7. The method for preparing the bimetallic layered hydroxide according to claim 5, wherein, Carbon dioxide is not introduced during the reaction.

8. The method for preparing the bimetallic layered hydroxide according to claim 4, wherein, The molar ratio of M(II) to M(III) is 2M(II) / M(III) = 3.6 - 9.

0.

9. The method for preparing the bimetallic layered hydroxide according to claim 4, wherein, The temperature of the hydrothermal synthesis reaction is 140°C - 200°C.

10. The method for preparing the bimetallic layered hydroxide according to claim 4, wherein, Further surface treatment is carried out.

11. The method for preparing the bimetallic layered hydroxide according to claim 4, wherein, The M(II) source is 4MgCO3. Mg(OH)2 4H2O.

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