Water-based shielding coating

Abstract

The invention provides a water-based shielding coating, the coating is a functional filler and polyester resin composite coating, the functional filler is CH3NH3PbI3 perovskite powder with an excellent chemical structure and high purity, and the obtained coating has excellent radiation shielding performance.

Description

Technical Field

[0001] This invention relates to a water-based shielding coating, specifically a CH3NH3PbI3 powder polyester composite coating material, belonging to the field of functional material preparation technology, and specifically to the field of shielding functional coating technology. Background Technology

[0002] Waterborne polyester resin is a type of polyester resin that is soluble in water and belongs to waterborne coatings. With the rapid development of the national economy, infrastructure, and urbanization, there is a need for continuous innovation in my country's waterborne coatings industry to produce new, environmentally friendly, and cost-effective coatings. This will allow the overall level of the coatings industry to be researched and improved. Waterborne coatings can better meet the requirements of green and environmentally friendly coatings, and their potential benefits are immeasurable. While waterborne coatings have achieved superior performance to date, there are still some shortcomings in their ability to completely replace solvent-based coatings.

[0003] (1) The dispersion medium of water-based coatings is water. Water has a high surface tension and a large latent heat of vaporization. Therefore, the biggest factor affecting the popularization and promotion of water-based coatings is the high requirements for the temperature and humidity of the construction environment. This requires the formulation technology and construction process to work together to solve the problem.

[0004] (2) Water-based coatings still have shortcomings in terms of hydrophilicity and water resistance. The main film-forming resin of water-based coatings contains many hydrophilic groups or substances to stabilize water solubility or dispersion in water, but this will inevitably affect the water resistance of the coating. However, the water resistance of many water-based coatings is relatively worse than that of solvent-based coatings of the same type, which will affect the widespread application of water-based coatings.

[0005] (3) Currently, some water-based coatings contain water-soluble cosolvents and other additives. However, although the amount of some solvents or additives consumed is very small, they are highly toxic and cannot achieve the concept of green and environmentally friendly water-based coatings.

[0006] (4) Traditional catalysts adapted to waterborne alkyd resin systems lose some activity in waterborne systems. Ester bonds are easily hydrolyzed in waterborne systems. Therefore, a new type of environmentally friendly catalyst can accelerate the drying speed of waterborne alkyd resins and increase the crosslinking density. At present, new catalytic systems and methods to improve the hydrolytic stability of ester bonds still need to be studied and solved.

[0007] Currently, the commonly used shielding materials in the field of gamma shielding are mainly metals, metal matrix composites, and concrete. However, they are characterized by high density, large mass, difficult processing, and inflexible application. Polymers, due to their mechanical, electrical, thermal, and multifunctional properties, have promising application prospects. Composite materials made from polymers and functional fillers have the advantages of low weight, good flexibility, and high processability, and many researchers are studying reinforced composite shielding materials for specific radiation shielding applications. Polymer-based radiation shielding materials not only overcome the disadvantages of traditional radiation shielding materials, such as difficult processing, but also have good shielding performance against high-energy radiation. In polymer radiation shielding composites, the polymer matrix and functional fillers contribute differently to the performance of the composite material.

[0008] Polymer matrix materials serve a supporting and bonding function. Although they do not possess superior radiation shielding performance, they should exhibit appropriate physical, chemical, and mechanical properties depending on the specific application conditions. Researchers in the field of radiation shielding have studied many polymer matrices suitable for gamma-ray shielding, such as CN115304982B, a shielding coating for spaceborne integrated circuit packaging and its preparation method, which belongs to the field of functional material preparation technology, specifically involving the field of special functional coating technology. This invention solves the shortcomings of existing traditional radiation shielding materials, such as high cost, high density, and poor mechanical properties. This invention combines lead halide perovskite powder with resin materials, combining the advantages of each component to construct multiple high-performance composite coatings. Simultaneously, it utilizes the synergistic effect of the multi-component materials of lead halide perovskite powder to achieve shielding against various high-energy rays and suppress the generation of secondary particles. Furthermore, the composite coating contains numerous interfaces between lead halide perovskite and resin, constructing a structure with alternating high and low Z-weighted materials. This further suppresses bremsstrahlung radiation generated by the interaction of high-energy electrons with high-Z-weighted materials. The above research indicates that there are many types of polymer matrices used for radiation shielding, such as rubber, polyethylene, polyester, and epoxy resin. Among these, polyester resin has advantages such as low cost and ease of processing. This paper uses low-cost and easily processed epoxy resin as the matrix for studying the shielding performance of polymer-based composite materials.

[0009] Functional fillers used in polymer-based composites should not only contribute to the hardness and wear resistance of the composites but also possess excellent gamma-ray shielding performance. For gamma-ray shielding, researchers have reported various functional fillers, such as elemental metals, metal oxides, lead materials, and rare earth materials, all of which exhibit some gamma-ray shielding performance. It can be observed that there are numerous types of functional fillers used in radiation shielding, and the radiation shielding performance of polymer-based composites is related to the type and particle size of the functional filler. Smaller particle sizes of the functional filler result in better radiation shielding performance; however, the composition of the functional filler has a greater impact on shielding performance. However, existing functional fillers mostly utilize traditional radiation shielding materials with relatively simple structures. Summary of the Invention

[0010] This invention provides a CH3NH3PbI3 perovskite powder with excellent chemical structure and high purity, and uses it as a functional filler to composite it with polyester resin to prepare a composite material with excellent radiation shielding performance, as detailed below: A water-based shielding coating comprising the following components in parts by weight.

[0011] 25-50 parts of water-based polyester resin; Dispersant 1.0-3 parts; 0.5-2 parts of defoamer; 0.1-1.5 parts of wetting agent; Leveling agent 0.2-2 parts; 4-15 parts of water-based amino resin; 10-15 parts of pigment titanium dioxide; 10-15 parts of filler CH3NH3PbI3 powder; 15-25 parts deionized water; CH3NH3PbI3 was obtained through one-step electrodeposition with ionic liquid, as detailed below: (1) Preparation of electrolyte: The electrolyte is composed of anhydrous lead tetrafluoroborate, methyl ammonium iodide, sodium iodide and 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid. The 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid is placed in an argon glove box, and then anhydrous lead tetrafluoroborate is added. After magnetic stirring for 1-2 hours, the mixture is filtered and the clear liquid is taken. Then, methyl ammonium iodide and sodium iodide are added to the clear liquid and stirred evenly to obtain the electrolyte. (2) One-step electrodeposition: Using a platinum sheet as the anode and iodine-fumigated carbon material as the cathode, electrodeposition is performed under a pulsed power supply. Electrolysis parameters: positive duty cycle 10-50%, negative duty cycle 10-50%, positive average current density 4-5 A / dm², negative average current density 1-2 A / dm².2 At a temperature of 30-35℃, stir, with an electrode distance of 4-5cm, for 10-15 minutes. Remove, wash and rinse with ethanol-distilled water-ethanol in sequence, dry with cold air, scrape off the powder, and obtain CH3NH3PbI3 particles. (3) Place the carbon material after scraping powder at a temperature of 150-160℃ and burn it in air for 10-15 seconds. Then cool the carbon material to 0℃, put it in an iodine fumigation furnace for 20-30 seconds, take it out, use it as a cathode, and repeat the operation process of step (2). (4) The collected CH3NH3PbI3 is purified and pulverized.

[0012] The aqueous polyester resin is an aqueous saturated polyester resin with a hydroxyl value of 30 to 150 mg KOH / g.

[0013] The electrolyte consists of 5-10 g / L anhydrous lead tetrafluoroborate, 10-15 g / L methylammonium iodide, 4-5 g / L sodium iodide, and 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid.

[0014] The purification process is as follows: CH3NH3PbI3 particles are placed in a nitrogen furnace, heated to 100-120℃, heat-treated for 10-15 minutes, and then removed.

[0015] The crushing process involves placing the purified CH3NH3PbI3 particles into a low-temperature crusher for crushing to obtain CH3NH3PbI3 powder with a size of 1-10μm.

[0016] A method for preparing a water-based polyester coating includes the following steps: S1. Add the dispersant, wetting agent and leveling agent to deionized water, stir at 400-800 r / min for 10-30 min until fully mixed, then add titanium dioxide and CH3NH3PbI3 powder, stir at medium speed of 200-500 r / min until uniform, then add waterborne amino resin at medium speed of 200-500 r / min until uniformly dispersed; S2. Add the waterborne polyester resin to the system obtained in step S1, and stir at 400-800 r / min for 10-40 min until it is evenly dispersed; S3. Add the defoamer to the system obtained in step S2, stir and disperse at 300-600 r / min for 15-30 min, let stand, and pass through an 800-mesh sieve to obtain the product; The leveling agent is selected from polyether silicone or polyester silicone.

[0017] The dispersant is selected from polyacrylic acid, polyvinylpyrrolidone, or polymethacrylic acid.

[0018] The wetting agent is selected from alkylphenol polyethylene ether, polyoxyethylene glycol alkyl ester, or polyoxyethylene alkyl ether.

[0019] Existing technologies include a two-step method for preparing perovskite thin films, such as CN114134549A, which is based on electrochemical two-step synthesis. This method improves the electrochemical synthesis of perovskite thin films through sulfate anion modification. It relates to the fields of perovskite solar cells and electrochemistry. The method includes: depositing a sulfate anion-modified lead metal layer on ITO glass; and converting the sulfate anion-modified lead metal layer on the ITO glass into a sulfate anion-modified perovskite thin film. By implementing this invention, the method for electrochemical synthesis of perovskite thin films can be effectively improved, thereby obtaining perovskite solar cells with higher photoelectric conversion efficiency. Simultaneously, it can overcome the limitation of flat substrates, achieving uniform and conformal growth of perovskite thin films on textured heterojunction solar cells.

[0020] For example, CN107195788A discloses a method for preparing an organic-inorganic hybrid perovskite material thin film, including the following steps: S1, Preparation of dense titanium oxide substrate: Using titanium oxide slurry, spin-coat on the surface of conductive FTO glass for 30s, dry at 120℃ for 4min, repeat twice, and then anneal at 500℃ for 15min.

[0021] S2, Electrochemical preparation of lead precursor thin film: Lead iodide, sodium iodide and ethylene glycol tert-butyl ether were added to isopropanol solution to make concentrations of 10mM, 1M and 500mM respectively to prepare electrolyte. 200mL of this electrolyte was taken, and a conductive FTO glass with a dense titanium oxide substrate was used as the working electrode and a platinum electrode (2x2cm2) was used as the counter electrode. A DC bias voltage of -2.5V was applied to the working electrode for 5min to obtain a dense titanium oxide substrate covered with lead film.

[0022] S3, Electrochemical preparation of perovskite thin films: Methylamine iodide was added to an isopropanol solution to a concentration of 10 mg / mL as an electrolyte. 200 mL of this electrolyte was used as the working electrode, and a platinum electrode (2 x 2 cm2) was used as the counter electrode. A DC bias of +2.5 V was applied to the working electrode for 5 min to obtain the perovskite thin film.

[0023] The above process has the following problems: (1) The process involves two steps, resulting in low cost-effectiveness and purity: The above process involves electrochemical preparation of lead film, followed by electrochemical preparation of CH3NH3PbI3 layer, and then control of Pb near the cathode of electrolyte by electrochemical parameters. 2+ CH3NH3 + and I -Ions, in which lead is obtained by oxidation of lead layer, it is difficult to control the ratio of each component, which leads to extremely low purity of product, and thus significantly reduces the shielding effect of product; (2) Both of the above patents are for preparing thin film materials. Once the thin film material is obtained, it is impossible to purify the material. Simply put, if a Pb electroplating layer is prepared first, the Pb layer that cannot be completely oxidized will inevitably be an impurity and cannot be removed. If a person skilled in the art wants to use the thin film material, such as scraping the coating on the above electrode to obtain shielding layer powder, the lead in it cannot be separated, that is, Pb metal cannot be separated from CH3NH3PbI3, or cannot be easily separated.

[0024] Based on the above, this invention improves the electrolyte conditions, uses an ionic liquid as the conductive medium, and employs an iodine-containing cathode rod as the cathode, effectively enriching CH3NH3 on the cathode surface under pulsed conditions. + Pb 2+ and I - A CH3NH3PbI3 layer was prepared on the cathode surface using a one-step method, and then I was removed by a simple purification method to obtain CH3NH3PbI3 powder with a very high degree of purification, as detailed below.

[0025] This invention uses 1-methyl-3-butylimidazolium tetrafluoroborate as the ionic liquid electrolyte. The ionic liquid can remain in a liquid state at room temperature. The typical expression for an ionic liquid is [N... + ]X - , where [N + [BMIM+] (1-butyl-3-methylimidazolium) and [EMIM+] (1-ethyl-3-methylimidazolium) are used as the ionic liquids. X- can be F-, Cl-, Br-, I-, NO3-, PF6-, or BF4-. This invention selects 1-methyl-3-butylimidazolium tetrafluoroborate as the ionic liquid through screening, as it offers a high cost-performance ratio. To match the ionic liquid, anhydrous lead tetrafluoroborate is used as the main salt. The [N] in the ionic liquid... + [Cannot be deposited at the cathode, while CH3NH3] + With Pb 2+ Iodine can be deposited at the cathode, and then provided as an iodine source with sodium iodide, and induced by stirring and pulsed power supply. - At the cathode, CH3NH3 + With Pb 2+ Co-deposition occurs, but the enrichment of I in the cathode is limited; therefore, the cathode rod containing I is used as the I... -The auxiliary ion source can effectively increase the yield of CH3NH3PbI3. Then, the CH3NH3PbI3 on ​​the cathode surface is scraped off by a scraping method. After iodine removal by evaporation, the powder is obtained by low-temperature pulverization. The iodine removal process must be carried out in a nitrogen atmosphere. Under air conditions, CH3NH3PbI3 will decompose at 100℃ to produce lead iodide and potassium ammonium iodide. If it is in a pure nitrogen atmosphere, it will decompose at around 230℃. If the carbon material after scraping is placed at a temperature of 150-160℃ in order to reuse the carbon rod, the excess residual CH3NH3PbI3 will decompose.

[0026] The final CH3NH3PbI3 powder is shown in the attached figure. Figure 1 As shown, the particles are 1-10 μm in size and are similar to round particles. The particles are generally dispersed and have almost no aggregation. It can be seen that the one-step electrodeposition of this invention is to deposit particles on the cathode surface rather than in the form of a thin film. This is due to the control of the electrodeposition conditions. The highly dispersed CH3NH3PbI3 can be effectively dispersed on the surface of the polyester coating, which is suitable for the shielding performance.

[0027] Additionally, as attached Figure 2 As shown, XRD tests were performed on the embodiments of the present invention and Comparative Example 2. Compared with Comparative Example 2, the main difference between Embodiment 2 and Comparative Example 2 is whether there is a PbI2 diffraction peak. In addition, the intensity of the derived peak in Embodiment 2 is significantly higher than that in Comparative Example 2. That is, the purity and crystal strength of the CH3NH3PbI3 powder prepared by the one-step method of the present invention are significantly higher than those of the two-step method in Comparative Example 2.

[0028] Beneficial technical effects (1) By improving the electrolyte condition, using an ionic liquid as the conductive medium, and using an iodine-containing cathode rod as the cathode, CH3NH3 can be effectively enriched on the cathode surface under pulsed conditions. + Pb 2+ and I - A CH3NH3PbI3 layer was prepared on the cathode surface in one step, and then I was removed by simple purification methods to obtain CH3NH3PbI3 powder with extremely high purification degree.

[0029] (2) Highly purified CH3NH3PbI3 powder was prepared and highly dispersed in the coating. Shielding performance tests showed that the polyester coating with CH3NH3PbI3 as filler exhibited superior gamma shielding performance, with a linear attenuation coefficient ranging from 0.08924 to 0.13100 cm⁻¹. -1 The mass decay coefficient is 0.05250-0.05822 cm⁻¹. 2 / g, with a half-value layer thickness of 5.291-7.766cm. Attached Figure Description

[0030] Appendix Figure 1 SEM image of CH3NH3PbI3 powder of the present invention.

[0031] Appendix Figure 2 XRD patterns of powders from embodiments of the present invention and Comparative Example 2. Implementation

[0032] The main steps of the embodiments and comparative examples of the present invention are as follows: S1. Add the dispersant, wetting agent and leveling agent to deionized water and stir until fully mixed. Then add titanium dioxide and CH3NH3PbI3 powder, stir at medium speed until uniform, and then add waterborne amino resin at medium speed until uniformly dispersed. S2. Add the water-based polyester resin to the system obtained in step S1 and stir until it is evenly dispersed; S3. Add the defoamer to the system obtained in step S2, stir to disperse, let stand, and then sieve to obtain the final product. Example 1

[0033] A water-based shielding coating comprising the following components in parts by weight: 25 parts of water-based polyester resin; 1.0 part of dispersant; 0.5 parts of defoamer; 0.1 parts wetting agent; 0.2 parts leveling agent; 4 parts of water-based amino resin; 10 parts of pigment titanium dioxide; 10 parts of filler CH3NH3PbI3 powder; 15 parts deionized water.

[0034] CH3NH3PbI3 was obtained through one-step electrodeposition with ionic liquid, as detailed below: (1) Preparation of electrolyte: The electrolyte is composed of 5 g / L anhydrous lead tetrafluoroborate, 10 g / L methyl ammonium iodide, 4 g / L sodium iodide and 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid. The 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid is placed in an argon glove box, and then anhydrous lead tetrafluoroborate is added. After magnetic stirring for 1-2 hours, the mixture is filtered and the clear liquid is taken. Then methyl ammonium iodide and sodium iodide are added to the clear liquid and stirred evenly to obtain the electrolyte.

[0035] (2) One-step electrodeposition: Using a platinum sheet as the anode and iodine-fumigated carbon material as the cathode, electrodeposition is performed under a pulsed power supply. Electrolysis parameters: positive duty cycle 10%, negative duty cycle 10%, positive average current density 4 A / dm², negative average current density 1 A / dm². 2At 30℃, the mixture was stirred with an electrode distance of 4cm for 10 minutes. The mixture was then removed, washed and rinsed with ethanol-distilled water-ethanol in sequence, dried with cold air, and scraped to obtain CH3NH3PbI3 particles.

[0036] (3) Place the carbon material after scraping powder at a temperature of 150°C and burn it in air for 10 seconds. Then cool the carbon material to 0°C, put it in an iodine fumigation furnace for 20 seconds, take it out, and use it as a cathode. Repeat the operation process of step (2).

[0037] (4) The collected CH3NH3PbI3 is purified and crushed. The purification process is as follows: CH3NH3PbI3 particles are placed in a nitrogen furnace, heated to 100°C, heat-treated for 10 minutes, and then removed. The crushing process is as follows: the purified CH3NH3PbI3 particles are placed in a low-temperature crusher for crushing to obtain CH3NH3PbI3 powder. Example 2

[0038] A water-based shielding coating comprising the following components in parts by weight: 37.5 parts of waterborne polyester resin; 2 parts dispersant; 1.25 parts of defoamer; 0.8 parts wetting agent; 1.1 parts leveling agent; 9.5 parts of waterborne amino resin; 12.5 parts of pigment titanium dioxide; 10 parts of filler CH3NH3PbI3 powder; 20 parts deionized water.

[0039] CH3NH3PbI3 was obtained through one-step electrodeposition with ionic liquid, as detailed below: (1) Preparation of electrolyte: The electrolyte is composed of 7.5 g / L anhydrous lead tetrafluoroborate, 7.5 g / L methyl ammonium iodide, 4.5 g / L sodium iodide and 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid. The 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid is placed in an argon glove box, and then anhydrous lead tetrafluoroborate is added. After magnetic stirring for 1.5 h, the mixture is filtered and the clear liquid is taken. Then methyl ammonium iodide and sodium iodide are added to the clear liquid and stirred evenly to obtain the electrolyte.

[0040] (2) One-step electrodeposition: Using a platinum sheet as the anode and iodine-fumigated carbon material as the cathode, electrodeposition is performed under a pulsed power supply. Electrolysis parameters: positive duty cycle 30%, negative duty cycle 30%, positive average current density 4.5 A / dm², negative average current density 1.5 A / dm². 2The temperature was 32.5℃, the mixture was stirred, the electrode distance was 4.5cm, and the time was 12.5min. The mixture was then removed, washed and rinsed with ethanol-distilled water-ethanol in sequence, dried with cold air, and scraped off to obtain CH3NH3PbI3 particles.

[0041] (3) Place the scraped carbon material at a temperature of 155°C and burn it in air for 12.5 seconds. Then cool the carbon material to 0°C, put it in an iodine fumigation furnace for 25 seconds, take it out, use it as a cathode, and repeat the operation process of step (2).

[0042] (4) The collected CH3NH3PbI3 is purified and crushed. The purification process is as follows: CH3NH3PbI3 particles are placed in a nitrogen furnace, heated to 110°C, heat-treated for 12.5 min, and then removed. The crushing process is as follows: the purified CH3NH3PbI3 particles are placed in a low-temperature crusher for crushing to obtain CH3NH3PbI3 powder. Example 3

[0043] A water-based shielding coating comprising the following components in parts by weight: 37.5 parts of waterborne polyester resin; 2 parts dispersant; 1.25 parts of defoamer; 0.8 parts wetting agent; 1.1 parts leveling agent; 9.5 parts of waterborne amino resin; 12.5 parts of pigment titanium dioxide; 12.5 parts of filler CH3NH3PbI3 powder; 20 parts deionized water.

[0044] CH3NH3PbI3 was obtained through one-step electrodeposition with ionic liquid, as detailed below: (1) Preparation of electrolyte: The electrolyte is composed of 7.5 g / L anhydrous lead tetrafluoroborate, 7.5 g / L methyl ammonium iodide, 4.5 g / L sodium iodide and 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid. The 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid is placed in an argon glove box, and then anhydrous lead tetrafluoroborate is added. After magnetic stirring for 1.5 h, the mixture is filtered and the clear liquid is taken. Then methyl ammonium iodide and sodium iodide are added to the clear liquid and stirred evenly to obtain the electrolyte.

[0045] (2) One-step electrodeposition: Using a platinum sheet as the anode and iodine-fumigated carbon material as the cathode, electrodeposition is performed under a pulsed power supply. Electrolysis parameters: positive duty cycle 30%, negative duty cycle 30%, positive average current density 4.5 A / dm², negative average current density 1.5 A / dm². 2The temperature was 32.5℃, the mixture was stirred, the electrode distance was 4.5cm, and the time was 12.5min. The mixture was then removed, washed and rinsed with ethanol-distilled water-ethanol in sequence, dried with cold air, and scraped off to obtain CH3NH3PbI3 particles.

[0046] (3) Place the scraped carbon material at a temperature of 155°C and burn it in air for 12.5 seconds. Then cool the carbon material to 0°C, put it in an iodine fumigation furnace for 25 seconds, take it out, use it as a cathode, and repeat the operation process of step (2).

[0047] (4) The collected CH3NH3PbI3 is purified and crushed. The purification process is as follows: CH3NH3PbI3 particles are placed in a nitrogen furnace, heated to 110°C, heat-treated for 12.5 min, and then removed. The crushing process is as follows: the purified CH3NH3PbI3 particles are placed in a low-temperature crusher for crushing to obtain CH3NH3PbI3 powder. Example 4

[0048] A water-based shielding coating comprising the following components in parts by weight: 37.5 parts of waterborne polyester resin; 2 parts dispersant; 1.25 parts of defoamer; 0.8 parts wetting agent; 1.1 parts leveling agent; 9.5 parts of waterborne amino resin; 12.5 parts of pigment titanium dioxide; 15 parts of filler CH3NH3PbI3 powder; 20 parts deionized water.

[0049] CH3NH3PbI3 was obtained through one-step electrodeposition with ionic liquid, as detailed below: (1) Preparation of electrolyte: The electrolyte is composed of 7.5 g / L anhydrous lead tetrafluoroborate, 7.5 g / L methyl ammonium iodide, 4.5 g / L sodium iodide and 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid. The 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid is placed in an argon glove box, and then anhydrous lead tetrafluoroborate is added. After magnetic stirring for 1.5 h, the mixture is filtered and the clear liquid is taken. Then methyl ammonium iodide and sodium iodide are added to the clear liquid and stirred evenly to obtain the electrolyte.

[0050] (2) One-step electrodeposition: Using a platinum sheet as the anode and iodine-fumigated carbon material as the cathode, electrodeposition is performed under a pulsed power supply. Electrolysis parameters: positive duty cycle 30%, negative duty cycle 30%, positive average current density 4.5 A / dm², negative average current density 1.5 A / dm². 2The temperature was 32.5℃, the mixture was stirred, the electrode distance was 4.5cm, and the time was 12.5min. The mixture was then removed, washed and rinsed with ethanol-distilled water-ethanol in sequence, dried with cold air, and scraped off to obtain CH3NH3PbI3 particles.

[0051] (3) Place the scraped carbon material at a temperature of 155°C and burn it in air for 12.5 seconds. Then cool the carbon material to 0°C, put it in an iodine fumigation furnace for 25 seconds, take it out, use it as a cathode, and repeat the operation process of step (2).

[0052] (4) The collected CH3NH3PbI3 is purified and crushed. The purification process is as follows: CH3NH3PbI3 particles are placed in a nitrogen furnace, heated to 110°C, heat-treated for 12.5 min, and then removed. The crushing process is as follows: the purified CH3NH3PbI3 particles are placed in a low-temperature crusher for crushing to obtain CH3NH3PbI3 powder. Example 5

[0053] A water-based shielding coating comprising the following components in parts by weight: 50 parts of water-based polyester resin; 3 parts dispersant; 2 parts defoamer; 1.5 parts wetting agent; 2 parts leveling agent; 15 parts of water-based amino resin; 15 parts of titanium dioxide pigment; 15 parts of filler CH3NH3PbI3 powder; 25 parts deionized water.

[0054] CH3NH3PbI3 was obtained through one-step electrodeposition with ionic liquid, as detailed below: (1) Preparation of electrolyte: The electrolyte is composed of 10 g / L anhydrous lead tetrafluoroborate, 15 g / L methyl ammonium iodide, 5 g / L sodium iodide and 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid. The 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid is placed in an argon glove box, and then anhydrous lead tetrafluoroborate is added. After stirring magnetically for 2 hours, the mixture is filtered and the clear liquid is taken. Then, methyl ammonium iodide and sodium iodide are added to the clear liquid and stirred evenly to obtain the electrolyte.

[0055] (2) One-step electrodeposition: Using a platinum sheet as the anode and iodine-fumigated carbon material as the cathode, electrodeposition is performed under a pulsed power supply. Electrolysis parameters: positive duty cycle 50%, negative duty cycle 50%, positive average current density 5 A / dm², negative average current density 2 A / dm². 2At 35℃, the mixture was stirred with an electrode distance of 5cm for 15 minutes. The mixture was then removed, washed and rinsed with ethanol-distilled water-ethanol in sequence, dried with cold air, and scraped off to obtain CH3NH3PbI3 particles.

[0056] (3) Place the carbon material after scraping powder at a temperature of 160°C and burn it in air for 15 seconds. Then cool the carbon material to 0°C, put it in an iodine fumigation furnace for 30 seconds, take it out, use it as a cathode, and repeat the operation process of step (2).

[0057] (4) The collected CH3NH3PbI3 is purified and crushed. The purification process is as follows: CH3NH3PbI3 particles are placed in a nitrogen furnace, heated to 120°C, heat-treated for 15 minutes, and then removed. The crushing process is as follows: the purified CH3NH3PbI3 particles are placed in a low-temperature crusher for crushing to obtain CH3NH3PbI3 powder.

[0058] Comparative Example 1.

[0059] A water-based shielding coating comprising the following components in parts by weight: 37.5 parts of waterborne polyester resin; 2 parts dispersant; 1.25 parts of defoamer; 0.8 parts wetting agent; 1.1 parts leveling agent; 9.5 parts of waterborne amino resin; 22.5 parts of titanium dioxide pigment; 20 parts deionized water.

[0060] Comparative Example 2.

[0061] A water-based shielding coating comprising the following components in parts by weight: 37.5 parts of waterborne polyester resin; 2 parts dispersant; 1.25 parts of defoamer; 0.8 parts wetting agent; 1.1 parts leveling agent; 9.5 parts of waterborne amino resin; 12.5 parts of pigment titanium dioxide; 10 parts of filler CH3NH3PbI3 powder; 20 parts deionized water.

[0062] CH3NH3PbI3 is obtained through the following process: (1) Add lead iodide, sodium iodide and ethylene glycol tert-butyl ether to the isopropanol solution to make their concentrations 10mM, 1M and 500mM respectively. Take 200mL of this electrolyte, use carbon material as cathode and platinum sheet as anode, apply DC pulse of 20V to the working electrode for 1s, then apply DC pulse of 2.5V for 5min to obtain lead film.

[0063] (2) Add methyl iodide to the isopropanol solution to make its concentration 10 mg / mL. Take 200 mL of this electrolyte, use the lead film sample as the working electrode and the platinum electrode as the counter electrode. Apply a 5 Hz AC voltage (square wave, duty cycle 1:1) ± 2.5 V to the working electrode for 5 min. Take it out and wash it with ethanol-distilled water-ethanol in sequence. Dry it with cold air and scrape off the powder to obtain CH3NH3PbI3 particles.

[0064] (3) Crushing and purification process: CH3NH3PbI3 particles are placed in a nitrogen furnace, heated to 110°C, heat-treated for 12.5 min, and then removed. The crushing process is to place the purified CH3NH3PbI3 particles in a low-temperature crusher for crushing to obtain CH3NH3PbI3 powder.

[0065]

[0066] As mentioned above, the linear attenuation coefficient represents the probability of any interaction between photons within a unit length. It represents the total probability of the photoelectric effect, Compton scattering, and electron-electron pair effects occurring, and is a parameter that needs to be studied in various radiation shielding materials.

[0067] The mass attenuation coefficient is a measure of the number of photons that interact with the target material (which may be absorbed or scattered). It represents the probability of a photon interacting with the material and is the ratio of the linear attenuation coefficient to the material density.

[0068] The half-value layer is the thickness of the shielding material required to reduce the intensity of gamma-ray radiation to half of its initial intensity.

[0069] Based on the table above, the linear attenuation coefficients of Examples 2-4 of the present invention range from 0.08924 to 0.13100 cm⁻¹. -1 The mass decay coefficient is 0.05250-0.05822 cm⁻¹. 2 / g, with a half-value layer thickness of 5.291-7.766cm, which is far superior to the blank coating of Comparative Example 1 and the shielding material prepared by the two-step method of Comparative Example 2.

[0070] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A water-based shielding coating, characterized in that, It contains the following components in parts by weight: 25-50 parts of water-based polyester resin; Dispersant 1.0-3 parts; 0.5-2 parts of defoamer; 0.1-1.5 parts of wetting agent; Leveling agent 0.2-2 parts; 4-15 parts of water-based amino resin; 10-15 parts of pigment titanium dioxide; 10-15 parts of filler CH3NH3PbI3 powder; 15-25 parts deionized water CH3NH3PbI3 was obtained through one-step electrodeposition with ionic liquid, as detailed below: (1) Preparation of electrolyte: The electrolyte is composed of anhydrous lead tetrafluoroborate, methyl ammonium iodide, sodium iodide and 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid. The 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid is placed in an argon glove box, and then anhydrous lead tetrafluoroborate is added. After magnetic stirring for 1-2 hours, the mixture is filtered and the clear liquid is taken. Then, methyl ammonium iodide and sodium iodide are added to the clear liquid and stirred evenly to obtain the electrolyte. (2) One-step electrodeposition: Using a platinum sheet as the anode and iodine-fumigated carbon material as the cathode, electrodeposition is performed under a pulsed power supply. Electrolysis parameters: positive duty cycle 10-50%, negative duty cycle 10-50%, positive average current density 4-5 A / dm², negative average current density 1-2 A / dm². 2 At a temperature of 30-35℃, stir, with an electrode distance of 4-5cm, for 10-15 minutes. Remove, wash and rinse with ethanol-distilled water-ethanol in sequence, dry with cold air, scrape off the powder, and obtain CH3NH3PbI3 particles. (3) Place the carbon material after scraping powder at a temperature of 150-160℃ and burn it in air for 10-15 seconds. Then cool the carbon material to 0℃, put it in an iodine fumigation furnace for 20-30 seconds, take it out, use it as a cathode, and repeat the operation process of step (2). (4) The collected CH3NH3PbI3 is purified and pulverized.

2. The water-based shielding coating as described in claim 1, characterized in that... The aqueous polyester resin is an aqueous saturated polyester resin with a hydroxyl value of 30 to 150 mg KOH / g.

3. The water-based shielding coating as described in claim 1, characterized in that... The electrolyte consists of 5-10 g / L anhydrous lead tetrafluoroborate, 10-15 g / L methylammonium iodide, 4-5 g / L sodium iodide, and 1-methyl-3-butylimidazolium tetrafluoroborate ionic liquid.

4. The water-based shielding coating as described in claim 1, characterized in that... The purification process is as follows: CH3NH3PbI3 particles are placed in a nitrogen furnace, heated to 100-120℃, heat-treated for 10-15 minutes, and then removed.

5. The water-based shielding coating as described in claim 1, characterized in that... The crushing process involves placing the purified CH3NH3PbI3 particles into a low-temperature crusher for crushing to obtain CH3NH3PbI3 powder with a size of 1-10μm.

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