A modified illite, its preparation method and application

Abstract

This invention provides a modified illite, its preparation method, and its application, belonging to the field of functional materials technology. The preparation method of the modified illite of this invention includes the following steps: (1) first, pulverizing the illite, and then adjusting the water content of the illite to below 5%; (2) microwave activation of the illite at a power of 600-800W for 10-30 minutes to obtain the modified illite. This invention uses illite as raw material and modifies it through a microwave activation process, introducing oxygen vacancies and lattice distortion into the illite crystal structure, enhancing its phonon scattering, improving its infrared radiation efficiency, and preparing a high-performance infrared radiation functional powder.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to a modified illite, its preparation method, and its application. Background Technology

[0002] Infrared radiation materials have important applications in energy-saving technologies by enhancing surface thermal radiation efficiency. In existing technologies, infrared radiation coatings mainly use silicon carbide, ferrite, and other materials as functional fillers, but these materials have problems such as low emissivity (usually 0.80-0.85), poor adhesion to the substrate, and high cost.

[0003] Illite, as a natural layered silicate mineral, has the advantages of being widely available and inexpensive. However, the infrared radiation performance of its natural form is limited, making it difficult to meet the requirements of safe, green, environmentally friendly, high-performance, and multifunctional materials. Summary of the Invention

[0004] To address the problem of low normal total emissivity in existing infrared radiation materials, this invention provides a modified illite with high normal total emissivity, its preparation method, and its application. To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing modified illite, comprising the following steps: (1) First, crush the illite, and then adjust the moisture content of the illite to below 5%; (2) Microwave activation of illite with a power of 600-800W for 10-30 minutes to obtain the modified illite.

[0005] illite is a typical dioctahedral layered silicate mineral. Its basic structural unit is composed of silicon-oxygen tetrahedral sheets and aluminum-oxygen octahedral sheets stacked in a 2:1 ratio, with potassium ions (K) forming the interlayer. + To balance the charge and maintain structural stability, illite's chemical composition is mainly composed of SiO2 and Al2O3, with a relatively high amount of Al in the tetrahedral plates. 3+ Replacement of Si 4+ This phenomenon, caused by natural lattice distortion and cation substitution, results in illite itself having certain lattice defects and stresses.

[0006] Microwave activation is a method of overall heating that can rapidly and relatively uniformly heat a material. More importantly, in addition to the thermal effect (temperature increase), microwave energy also produces non-thermal effects. These non-thermal effects act directly on the ionic or chemical bonds of illite, for example, by inducing the distortion or breakage of polar bonds (such as Al-O and Si-O bonds) through electric field forces, thereby more effectively inducing defects at specific locations in the crystal lattice, rather than simply relying on overall temperature rise.

[0007] This invention utilizes microwaves to directly act on illite. Under the influence of the microwave field, components in the illite lattice that have a strong ability to absorb microwave energy (such as aluminum octahedra, structural water, or hydroxyl groups) will locally and rapidly heat up. This will lead to the following: (1) hydroxyl groups (-OH) in layered silicate minerals can be removed under microwave action, that is, they will detach from the lattice in the form of water molecules, thereby leaving oxygen vacancies in situ; (2) the microwave electric field drives negatively charged oxygen ions (O2- ... 2- ) directional migration occurs, and when these ions migrate to the crystal surface or combine with other defects in the lattice, oxygen vacancies are also generated inside the lattice; (3) potassium ions (K) in the illite interlayer domain + Under microwave irradiation, oxygen ions migrate or rearrange locally, which alters the local electric field in the region, thereby affecting the stability of surrounding oxygen ions and facilitating the formation of oxygen vacancies. Therefore, microwave activation introduces oxygen vacancies into illite.

[0008] The generation of oxygen vacancies disrupts the original charge balance and periodic potential field of the crystal lattice, causing surrounding atoms to rearrange their positions in search of a new equilibrium, thus inducing local lattice distortion. This distortion manifests microscopically as changes in interatomic spacing, bond angle distortion, and alterations in the coordination environment. The continuous action of a microwave field makes this atomic rearrangement more pronounced, even inducing microscopic strain, thereby enhancing lattice distortion.

[0009] Introducing oxygen vacancies and lattice distortions can enhance phonon scattering in illite, thereby improving its infrared radiation efficiency. Specifically, after microwave treatment, the oxygen vacancies and lattice distortions generated in illite crystals, as defects in the crystal structure, severely disrupt the periodic vibrations of the lattice. When thermal energy (phonons) propagates in the lattice, these defects become strong scattering centers, significantly increasing the probability of phonon scattering and thus enhancing the material's anharmonicity to thermal vibrations. This is beneficial for converting thermal energy into infrared radiation energy. Successful defect engineering is expected to significantly improve the infrared emissivity of illite materials. Its normal emissivity or hemispherical total emissivity in specific wavelength bands (such as mid-infrared 3-5 μm or 8-14 μm) can be directly measured using an infrared emissivity meter. High-performance infrared radiation materials have broad application prospects in industrial heating (such as infrared drying and baking paint), energy-saving buildings (infrared radiation cooling), and thermal energy utilization.

[0010] This invention is the first to directly apply microwave activation technology to illite. By controlling the power and time of microwave activation, the layered structure of illite is effectively opened using molecular-level heating, improving the surface activity and reactivity of illite, which is beneficial for subsequent electrostatic spraying and coating density. The modified illite of this invention can also be used to prepare high-performance infrared radiation materials.

[0011] In a preferred embodiment of the preparation method of the modified illite described in this invention, the illite is derived from natural illite ore. Natural illite ore is mainly composed of illite, and also contains associated minerals such as quartz, feldspar, and kaolinite.

[0012] In a preferred embodiment of the preparation method of the modified illite described in this invention, the microwave activation power is 700-750W; and / or the microwave activation time is 15-20 minutes. Studies have shown that under the preferred microwave activation conditions, the surface activity and reactivity of illite are further improved, which is more beneficial for subsequent electrostatic spraying and coating density.

[0013] In a more preferred embodiment of the method for preparing modified illite according to the present invention, the power of microwave activation is 700W; and / or the microwave activation time is 20 minutes.

[0014] In a preferred embodiment of the method for preparing modified illite according to the present invention, in step (1), illite is pulverized to a particle size D. 50 The size is below 8.970 μm; and / or the water content of the illite is adjusted to 3%-5%.

[0015] In a preferred embodiment of the method for preparing modified illite according to the present invention, in step (1), the water content of the illite is adjusted to 4%.

[0016] Secondly, the present invention provides a modified illite, which is prepared by the above method.

[0017] Thirdly, the present invention provides the application of the above-mentioned modified illite in the use of bioaerosol simulating tracers, in the preparation of electrostatic spraying powders, or in the preparation of plastic wrap.

[0018] In a preferred embodiment of the application described in this invention, the modified illite is used as a bioaerosol simulating tracer for multimodal detection. The modified illite of this invention can be used as a multimodal bioaerosol simulating tracer. By controlling the particle size and temperature of the material, it simulates the physical characteristics of exhaled aerosols (e.g., 37°C temperature, 1-5 μm particle size), and utilizes its infrared radiation and mineral fingerprints for multimodal detection, thereby improving the fidelity and safety of propagation path simulation.

[0019] The modified illite of this invention exhibits enhanced radiation intensity in the mid-infrared band (8-14 μm) after heating (e.g., 37°C), with a relative radiation intensity of 0.9978 at 8.5 μm. This infrared radiation can be tracked in real-time using an infrared thermal imager. The TOT layered structure and interlayer ions of the modified illite of this invention produce unique X-ray diffraction (XRD) and Fourier transform infrared (FTIR) characteristics, allowing for terminal quantitative analysis using its mineral fingerprint specificity.

[0020] The modified illite of this invention features controllable particle size. Through ultrafine processing, the particle size can be controlled between 0.5-25 μm, covering the particle size range of pathogen aerosols in the air. Furthermore, its temperature is adjustable; heat treatment (37-40℃) simulates the temperature of exhaled aerosols, exhibiting good thermal stability.

[0021] As a preferred embodiment of the application described in this invention, the method for using the modified illite as a bioaerosol mimic tracer for multimodal detection includes the following steps: The modified illite of this invention is heated to a target temperature (e.g., 37°C) and released through an aerosol generator to simulate the aerosols exhaled by the human body. The thermal signal diffusion path is tracked in real time using an infrared thermal imager (operating band 8-14μm) (utilizing infrared emissivity). Air samples were collected, and mineral fingerprints were analyzed using XRD or FTIR for quantitative verification.

[0022] Fourthly, the present invention provides an electrostatic spraying powder containing the above-mentioned modified illite.

[0023] The modified illite of the present invention was used in electrostatic spraying powder, and the resulting electrostatic spraying powder exhibited excellent infrared radiation performance.

[0024] As a preferred embodiment of the electrostatic spraying powder of the present invention, according to Appendix A of GB / T 4653-1984, the normal total emissivity of the electrostatic spraying powder at 85°C is not less than 0.88, preferably 0.89 or higher. The wavelength range for detection is 2.5-25 μm.

[0025] As a preferred embodiment of the electrostatic spraying powder of the present invention, the electrostatic spraying powder is an intelligent temperature-controlled electrostatic spraying powder.

[0026] As a preferred embodiment of the electrostatic spraying powder of the present invention, the electrostatic spraying powder comprises the following components in parts by weight: 30-50 parts of the modified illite, 40-60 parts of resin powder, 1-3 parts of leveling agent, and 0.5-1.5 parts of degassing agent.

[0027] According to GB / T 4653-1984 standard, the above-mentioned electrostatic spraying powder exhibits a normal total emissivity of over 0.89 at 85℃, which is superior to traditional infrared radiation materials. The electrostatic spraying powder of this invention maintains a consistently high radiation intensity in the 8-14μm atmospheric window band (e.g., reaching 0.96 at 9μm), which ensures its high efficiency and energy-saving performance in intelligent temperature control applications.

[0028] In addition, the electrostatic spraying powder of the present invention has the following advantages: (1) Excellent construction performance: uniform particle size distribution, good electrostatic spraying performance, and uniform and dense coating; (2) Strong environmental adaptability: the coating has stable performance at a working temperature of 85℃ and is suitable for building energy conservation fields such as smart windows; (3) Obvious cost advantage: natural illite is used as the main raw material, which greatly reduces the cost of raw materials.

[0029] In a more preferred embodiment of the electrostatic spraying powder of the present invention, the modified illite is 35-45 parts by weight and the resin powder is 50-60 parts by weight.

[0030] As a preferred embodiment of the electrostatic spraying powder of the present invention, the electrostatic spraying powder satisfies at least one of the following (A)-(D): (A) The resin powder is epoxy resin powder; (B) The leveling agent is at least one of acrylate, cellulose acetate butyrate, polyvinyl butyral, and α-methylstyrene; (C) The degassing agent is at least one of benzoin and 2-hydroxy-2-phenylacetophenone; (D) The sieve aperture of the electrostatic spraying powder is 30-50 μm.

[0031] Fifthly, the present invention provides a method for preparing the above-mentioned electrostatic spraying powder, which includes the following steps: first, mixing the components of the electrostatic spraying powder evenly according to the ratio, and then sequentially performing melt extrusion, cooling and crushing and grinding and sieving to obtain the electrostatic spraying powder.

[0032] In a sixth aspect, the present invention provides a food preservation film containing the above-mentioned modified illite.

[0033] In a preferred embodiment of the food preservation film of the present invention, the food preservation film comprises polyethylene resin and the modified illite. The food preservation film of the present invention has high air permeability.

[0034] The preparation method of the food preservation film of the present invention is as follows: the raw materials for preparing the food preservation film are mixed evenly in a high-speed mixer, and blow-molded by a single screw extruder at an extrusion temperature of 150-180℃ to obtain a food preservation film with a thickness of 0.02mm.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses illite as raw material and modifies it through a microwave activation process. Oxygen vacancies and lattice distortion are introduced into the illite crystal structure, enhancing phonon scattering and improving its infrared radiation efficiency, thus preparing a high-performance infrared radiation functional powder. Furthermore, by controlling the microwave power and activation time, this invention effectively opens the layered structure of illite, improving its surface activity and reactivity, which is beneficial for electrostatic spraying and coating density. Therefore, this invention solves the technical problems of low emissivity, high cost, and poor adhesion to substrates in existing infrared radiation materials.

[0036] The electrostatic spraying powder made from the modified illite of this invention has a normal total emissivity of over 0.89 (tested according to GB / T 4653-1984 standard), and exhibits excellent radiation characteristics in the 8-14μm atmospheric window band at an operating temperature of 85℃. The electrostatic spraying powder of this invention features strong adhesion, good thermal stability, and significant energy-saving effects, making it suitable for infrared radiation coatings in fields such as outdoor cabinets, transformers, energy-saving building doors and windows, and industrial energy-saving equipment.

[0037] The modified illite of the present invention can also be used to prepare food preservation film, and the food preservation film made from the modified illite of the present invention has high air permeability. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 This is a SEM image of the modified illite in Example 1 of the present invention.

[0040] Figure 2 This is a relative radiation spectrum curve of the electrostatic spraying powder in Example 6 of the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] Example 1 One embodiment of the modified illite and its preparation method of the present invention is as follows: (1) First, crush illite to its particle size D. 50 The thickness was 8.970 μm, and then the water content of illite was adjusted to 4%. (2) The illite treated in step (1) was microwave activated for 20 minutes in a microwave reactor at a power of 700W, and then cooled in the furnace to obtain functional powder, which is the modified illite material.

[0043] The structural state of the material modified by microwave activation in Example 1 of this invention was detected using a scanning electron microscope. The detection results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the modified illite material of the present invention has an irregular sheet-like structure with a large surface area of ​​5~10 µm and a sheet thickness of <100 nm; and its sheet structure has less stacking and is easy to disperse.

[0044] Example 2 One embodiment of the modified illite and its preparation method of the present invention is as follows: (1) First, crush illite to its particle size D. 50 The thickness was 8.970 μm, and then the water content of illite was adjusted to 4%. (2) The illite treated in step (1) was microwave activated for 15 minutes in a microwave reactor at a power of 750W and cooled with the furnace to obtain functional powder, which is the modified illite.

[0045] Example 3 One embodiment of the modified illite and its preparation method of the present invention is as follows: (1) First, crush illite to its particle size D. 50 The thickness was 8.970 μm, and then the water content of illite was adjusted to 4%. (2) The illite treated in step (1) was microwave activated for 18 minutes in a microwave reactor at a power of 725W and cooled with the furnace to obtain functional powder, which is the modified illite.

[0046] Example 4 One embodiment of the modified illite and its preparation method of the present invention is as follows: (1) First, crush illite to its particle size D. 50 The thickness was 8.970 μm, and then the water content of illite was adjusted to 3%. (2) The illite treated in step (1) was microwave activated for 30 minutes in a microwave reactor at a power of 600W and cooled with the furnace to obtain functional powder, which is the modified illite.

[0047] Example 5 One embodiment of the modified illite and its preparation method of the present invention is as follows: (1) First, crush illite to its particle size D. 50 The thickness was 8.970 μm, and then the water content of illite was adjusted to 5%. (2) Microwave activation of illite treated in step (1) is performed in a microwave reactor at a power of 800W for 10 minutes. After cooling in the furnace, functional powder is obtained, which is the modified illite.

[0048] Comparative Example 1 The only difference between this comparative modified illite preparation method and Example 1 is that in step (1), the water content of illite is adjusted to 5.5%. All other steps are the same as in Example 1.

[0049] Comparative Example 2 The only difference between this comparative modified illite preparation method and Example 1 is that in step (2), the illite treated in step (1) is microwave activated for 35 minutes at a power of 550W in a microwave reactor. All other steps are the same as in Example 1.

[0050] Comparative Example 3 The only difference between this comparative modified illite preparation method and Example 1 is that in step (2), the illite treated in step (1) is microwave activated for 8 minutes at a power of 850W in a microwave reactor. All other steps are the same as in Example 1.

[0051] Examples 6-12 and Comparative Examples 4-6 Examples 6-12 are examples of the electrostatic spraying powder of the present invention, which are composed of the following components: modified illite, epoxy resin powder (Dow DER663U), leveling agent (PV88) and benzoin.

[0052] Comparative Examples 4-6 are comparative examples of electrostatic spraying powders, which consist of the following components: comparative example modified illite, epoxy resin powder (Dow DER663U), leveling agent (PV88) and benzoin.

[0053] The modified illite used in the electrostatic spraying powders of Examples 6-12 and Comparative Examples 4-6, and the amounts of each component are shown in Table 1 below.

[0054] Table 1

[0055] The preparation methods of electrostatic spraying powders in Examples 6-12 and Comparative Examples 4-6 are as follows: (1) Add each component of the electrostatic spraying powder to the high-speed mixer according to the ratio, and mix in the high-speed mixer for 5 minutes; (2) The mixture obtained by mixing is melt-extruded through a twin-screw extruder. The temperature of each zone of the twin-screw extruder is: Zone I 90℃, Zone II 100℃, Zone III 110℃; (3) After cooling the extrudate obtained by melt extrusion, crush it, grind it with an ACM mill, and sieve out the 30-50μm spray powder to obtain the electrostatic spray powder.

[0056] The normal total emissivity in the 2.5-25 μm wavelength range, the relative radiation spectrum in the 8-14 μm range, the coating adhesion, and the thermal shock performance of the electrostatic sprayed powders of Examples 6-12 and Comparative Examples 4-6 were further tested according to the following standards. The test results are shown in Table 2 below. The relative radiation spectrum curve of the electrostatic sprayed powder of Example 6 is shown below. Figure 2 As shown.

[0057] Normal emissivity: Tested according to Appendix A of GB / T 4653-1984, at a test temperature of 85℃; Relative radiation spectrum: The test was conducted according to Appendix A of GB / T 4653-1984 at a test temperature of 85℃. Coating adhesion: Tested according to GB / T 9286 standard, which requires a grade of 1; Thermal shock performance: Tested according to GB / T 1735 standard, which requires no cracking or peeling.

[0058] Table 2 Performance test results of electrostatic sprayed powders in Examples 6-12 and Comparative Examples 4-6

[0059] As shown in Table 2, by controlling the microwave power and the treatment time, the layered structure of illite can be effectively opened, its surface activity and reactivity can be improved, which is beneficial to electrostatic spraying and coating density.

[0060] Example 13 One embodiment of the food preservation film of the present invention is made from the following raw materials in parts by weight: 80 parts of polyethylene resin and 20 parts of modified illite from Example 1.

[0061] The preparation method of the plastic wrap in this embodiment is as follows: the raw materials for preparing the plastic wrap are mixed evenly in a high-speed mixer, and blow-molded by a single screw extruder at an extrusion temperature of 150-180℃ to obtain a plastic wrap with a thickness of 0.02mm.

[0062] The performance of the cling film in this embodiment was tested, and the testing methods and results are shown in Table 3 below.

[0063] Table 3 As can be seen from Table 3, the food preservation film of the present invention has high air permeability.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing a modified illite, characterized by, Includes the following steps: (1) First, crush the illite, and then adjust the moisture content of the illite to below 5%; (2) Microwave activation of illite with a power of 600-800W for 10-30 minutes to obtain the modified illite.

2. The method for preparing modified illite according to claim 1, characterized in that, The power of the microwave activation is 700-750W; And / or, the microwave activation time is 15-20 minutes.

3. The method for preparing modified illite according to claim 1 or 2, characterized in that, In the step (1), the illite is pulverized to have a particle diameter D 50 of 8.970 μm or less; And / or, adjust the water content of the illite to 3%-5%.

4. A modified illite, characterized in that, It is prepared by the method described in any one of claims 1-3.

5. The use of the modified illite according to claim 4 in the preparation of bioaerosol mimicry tracers, electrostatic spraying powders, or plastic wrap.

6. An electrostatic spraying powder, characterized in that, It contains the modified illite as described in claim 4; preferably, according to GB / T4653-1984 standard, the normal total emissivity of the electrostatic spraying powder at 85°C is not less than 0.88, and more preferably 0.89 or higher.

7. The electrostatic spraying powder according to claim 6, characterized in that, It comprises the following components in parts by weight: 30-50 parts of the modified illite as described in claim 4, 40-60 parts of resin powder, 1-3 parts of leveling agent, and 0.5-1.5 parts of degassing agent.

8. The electrostatic spraying powder according to claim 7, characterized in that, The electrostatic spraying powder satisfies at least one of the following (A)-(D): (A) The resin powder is epoxy resin powder; (B) The leveling agent is at least one of acrylate, cellulose acetate butyrate, polyvinyl butyral, and α-methylstyrene; (C) The degassing agent is at least one of benzoin and 2-hydroxy-2-phenylacetophenone; (D) The sieve pore size of the electrostatic spraying powder is 30-50μm.

9. A method for preparing the electrostatic spraying powder according to any one of claims 6-8, characterized in that, Includes the following steps: First, the components of the electrostatic spraying powder are mixed evenly according to the specified ratio, and then melt extrusion, cooling and crushing, and grinding and sieving are carried out in sequence to obtain the electrostatic spraying powder.

10. A type of food preservation film, characterized in that, Contains the modified illite as described in claim 4; preferably, the food preservation film comprises polyethylene resin and the modified illite.

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