A UV-shielding composite material, its preparation method and application

Abstract

This invention belongs to the field of polymer materials technology and discloses an ultraviolet-shielding composite material, its preparation method, and its application. The synthesis method involves a hydrothermal reaction of cerium nitrate, bismuth ammonium citrate, and sodium sulfide at 170°C, followed by centrifugation, washing, drying, and grinding to obtain Bi₂S₃ / CeO₂ inorganic nanoparticles. These nanoparticles are then reacted with ethyl 3,4-dihydroxybenzoate, and the product is centrifuged, washed, dried, and ground to obtain the ultraviolet-shielding composite material. This invention provides a homogeneous composite material with a wide ultraviolet shielding band and excellent shielding performance without the need for high-temperature calcination. This invention is of significant importance for the protection of polymer materials against ultraviolet aging.

Description

Technical Field

[0001] This invention belongs to the field of polymer material applications, specifically relating to an ultraviolet shielding composite material, its preparation method, and its applications. Background Technology

[0002] Ultraviolet (UV) radiation in the 200-400nm wavelength range of sunlight poses the greatest threat to life on Earth and some outdoor materials. UV radiation can be divided into three bands based on its penetration ability: UVA (320-400nm), UVB (280-320nm), and UVC (200-280nm). UVA can effectively penetrate the ozone layer and almost completely reach the Earth's surface. UVA and UVB can cause severe damage to life and materials on Earth, leading to aging, burns, and in severe cases, inducing skin cell cancer. They also accelerate the photodecomposition and photooxidation of some materials, causing the breaking and decomposition of chemical bonds, resulting in material degeneration, aging, and loss of usability. Therefore, researching materials that can effectively shield against UV radiation, especially the entire UVA and UVB band, is a key focus.

[0003] The biggest drawback of inorganic UV shielding agents compared to organic UV shielding agents is their incompatibility with polymer matrices and their tendency to aggregate. Developing materials that are compatible with polymer matrices, have a wide UV shielding band, and strong shielding capabilities has become a key research focus. Summary of the Invention

[0004] In view of the shortcomings and deficiencies of the existing technology, the primary objective of this invention is to provide a method for synthesizing nano-cerium oxide / bismuth sulfide / ethyl 3,4-dihydroxybenzoate (Bi2S3 / CeO2 / EDHB) inorganic / organic composite materials, thereby obtaining composite materials that shield a wide range of ultraviolet rays and have good dispersibility in a polymer matrix.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for synthesizing a nano-(Bi2S3 / CeO2 / EDHB) composite material includes the following synthesis steps:

[0007] (1) Dissolve cerium nitrate in water and slowly add NH3·H2O to adjust the pH of the solution to ≈6.

[0008] (2) Bismuth ammonium citrate and sodium sulfide (Na2S) are dissolved in water of the same volume as in step (1) and mixed evenly.

[0009] (3) The solution from step (2) is mixed with the solution from step (1) and added to a polytetrafluoroethylene high-pressure reactor. The mixture is kept at 170°C for 12 hours. The product is filtered, washed, and dried to obtain the nano-cerium oxide / bismuth sulfide (Bi2S3 / CeO2) composite material.

[0010] (4) Nano Bi2S3 / CeO2 dissolves in ethanol aqueous solution and is ultrasonically dispersed uniformly.

[0011] (5) 3,4-Dihydroxybenzoate (EDHB) was dissolved in an equal volume of ethanol aqueous solution from step (4).

[0012] (6) The dispersion from step (4) is mixed with the solution from step (5), the pH is adjusted to approximately 6 with acetic acid, and the mixture is kept at 50°C for 10 hours under stirring. The product is then centrifuged, washed, dried, and ground to obtain the nanocomposite material (Bi2S3 / CeO2 / EDHB).

[0013] As a preferred option, the experimental water was self-made deionized water.

[0014] Preferably, the molar volume ratio (mmol:mL) of cerium nitrate to water is 1:50.

[0015] As a preferred option, the molar ratio (mol / mol) of Bi2S3 to CeO2 is (3-5):1.

[0016] Preferably, the molar ratio (mol / mol) of sodium sulfide to bismuth ammonium citrate is 3:2.

[0017] As a preferred option, the mass ratio (g / g) of Bi2S3 / CeO2 and EDHB is 1:0.8.

[0018] Preferably, the ethanol-water solution involved in the experiment has an ethanol to water volume ratio (mL / mL) of 1:9.

[0019] Preferably, the mass-to-volume ratio (g / mL) of Bi2S3 / CeO2 and the aqueous ethanol solution is 1:30.

[0020] As a preferred option, the mass ratio (g / g) of EDHB to Bi2S3 / CeO2 is 1:0.8.

[0021] Mix the PVC thoroughly with the DMF.

[0022] The obtained UV shielding agent (Bi2S3 / CeO2 / EDHB) was mixed with the PVC solution at room temperature and ultrasonically dispersed to obtain a film-forming solution.

[0023] After degassing the film-forming solution, it is cast onto a flat plate to form a film, allowed to stand in air to solidify, vacuum dried to constant weight, and then peeled off to obtain a UV-shielding film.

[0024] Preferably, the flat plate is a glass plate.

[0025] According to claim 1, the ultraviolet shielding composite material, its preparation method and application are characterized in that the drying temperature in step (3) is 80-100℃.

[0026] According to claim 1, the ultraviolet shielding composite material, its preparation method and application are characterized in that the drying temperature in step (6) is 60-80℃.

[0027] According to claim 9, the ultraviolet shielding composite material, its preparation method and application are characterized in that the structure of the nano-Bi2S3 / CeO2 composite material is that CeO2 and Bi2S3 exist in a uniformly dispersed manner, and EDHB is coated on the surface of the composite.

[0028] The nano-Bi2S3 / CeO2 / EDHB material prepared by the method of this invention not only possesses the ultraviolet absorption properties of CeO2, Bi2S3 and EDHB simultaneously, but also exhibits enhanced ultraviolet shielding performance across the entire UVA and UVB bands, while simultaneously demonstrating good dispersibility in polymer substrates, thus better leveraging the synergistic effect of the organic / inorganic composite ultraviolet shielding agent.

[0029] The method of this invention does not require high-temperature calcination of inorganic nanocomposites, and has the advantages of being environmentally friendly and having low energy consumption.

[0030] (5) The organic / inorganic nanocomposite structure obtained by the method of the present invention is prepared by dissolving raw material ions in a solvent, and the product composition is uniformly distributed. Attached Figure Description

[0031] Figure 1 The infrared spectra of S1 prepared in Example 1 and SA1 prepared in Example 4 are shown.

[0032] Figure 2 This is a high-resolution transmission electron microscope image of SA1 prepared in Example 4.

[0033] Figure 3 The image shows a comparison of the UV absorption curves of S1 prepared in Example 1 and SA1 prepared in Example 4.

[0034] Figure 4 Comparison of UV shielding performance of PVC composite films with SA1, SA2, and SA3 content of (2%). Detailed Implementation

[0035] The present invention will be further described below with reference to embodiments, but is not limited thereto.

[0036] It should be noted that, unless otherwise specified, the materials involved in the embodiments of the present invention are all publicly known and commonly used, and can be purchased conventionally.

[0037] Example 1

[0038] 1. Dissolve 0.43g of cerium nitrate hexahydrate in 50mL of deionized water, sonicate for 30min to obtain a homogeneous solution, and then slowly add NH3·H2O dropwise under vigorous stirring to adjust the pH of the solution system to ≈6.

[0039] 2. Dissolve 2.49g of bismuth ammonium citrate in 50mL of deionized water, sonicate for 30min, and then add 0.71g of sodium sulfide (Na2S) and mix well.

[0040] 3. The two solutions above are mixed and transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. The mixture is reacted at a constant temperature of 170°C for 12 hours. After cooling to room temperature, the mixture is centrifuged, washed, dried, and ground to obtain Bi2S3 / CeO2 powder (denoted as S1).

[0041] Example 2

[0042] 1. Dissolve 0.43g of cerium nitrate hexahydrate in 50mL of deionized water, sonicate for 30min to obtain a homogeneous solution, and then slowly add NH3·H2O dropwise under vigorous stirring to adjust the pH of the solution system to ≈6.

[0043] 2. Dissolve 3.32g of bismuth ammonium citrate in 50mL of deionized water, sonicate for 30min, and then add 0.94g of Na2S and mix well.

[0044] 3. The two solutions above are mixed and transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. The mixture is reacted at a constant temperature of 170°C for 12 hours. After cooling to room temperature, the mixture is centrifuged, washed, dried, and ground to obtain Bi2S3 / CeO2 powder (denoted as S2).

[0045] Example 3

[0046] 1. Dissolve 0.43g of cerium nitrate hexahydrate in 50mL of deionized water, sonicate for 30min to obtain a homogeneous solution, and then slowly add NH3·H2O dropwise under vigorous stirring to adjust the pH of the solution system to ≈6.

[0047] 2. Dissolve 4.15g of bismuth ammonium citrate in 50mL of deionized water, sonicate for 30min, and then add 1.17g of Na2S and mix well.

[0048] 3. The two solutions above are mixed and transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. The mixture is kept at 170°C for 12 hours. After cooling to room temperature, the mixture is centrifuged, washed, dried, and ground to obtain Bi2S3 / CeO2 powder (denoted as S3).

[0049] Example 4

[0050] Preparation of organic / inorganic composite UV shielding agent

[0051] 1 g of S1 Bi2S3 / CeO2 powder was dissolved in 30 mL of ethanol-water solution, and 0.8 g of ethyl 3,4-dihydroxybenzoate (EDHB) was dissolved in 30 mL of ethanol-water solution. The two ethanol-water solutions were mixed, and glacial acetic acid solution was slowly added dropwise while stirring to adjust the pH of the system to approximately 6. The mixture was ultrasonically dispersed, heated to 50°C, and reacted for 10 h. After cooling to room temperature, the mixture was centrifuged, and the resulting precipitate was washed, dried, and ground to obtain an organic / inorganic composite UV shielding agent (denoted as SA1). Organic / inorganic composite UV shielding agents corresponding to S2 and S3 (denoted as SA2 and SA3, respectively) were prepared using the same method.

[0052] Example 5

[0053] Preparation of composite films (taking PVC as a substrate as an example).

[0054] Under stirring conditions, 0.8 g of PVC powder was slowly added to 10 mL of DMF and stirred until evenly dispersed.

[0055] Weigh out a specified amount of nanoparticles and dissolve them in 10 mL of DMF. Disperse the mixture by ultrasonication for 1 h. Add the mixture to the above PVC solution, stir for 2 h, and then sonicate for 0.5 h to obtain a dispersion.

[0056] After degassing the film-forming solution, it is cast onto a flat plate to form a film, allowed to stand in the air to solidify, vacuum dried to constant weight, and then peeled off to obtain a UV shielding film.

[0057] 0.8g of PVC powder was slowly added to 20mL of DMF and stirred until evenly dispersed. Using the same method, pure PVC films without nanoparticles were prepared and their UV shielding performance was compared.

[0058] S1A, S2A, and S3A are each used as UV shielding agents, with a content of 2% in PVC.

[0059] Study on the UV shielding performance of PVC composite film.

[0060] 50 mL of RhB solution (10 -5 M) and 50 mg of ultraviolet photocatalyst TiO2 were mixed in a beaker and stirred magnetically for 30 min in the dark to allow adsorption equilibrium to be reached.

[0061] The PVC composite film to be tested was used as an ultraviolet shielding film to cover the mouth of the beaker. The RhB solution was vertically irradiated from directly above by an ultraviolet lamp (20W, 365nm wavelength). The solution was magnetically stirred and irradiated with ultraviolet light at room temperature. At ultraviolet irradiation time of 40, 80, 120, 160, 200, and 240 min, 4 mL of the solution was taken from the beaker, centrifuged, and the supernatant was collected for absorbance measurement. The absorbance at 554 nm was recorded. After the test, the solution was recovered, centrifuged and dispersed evenly, and then poured back into the beaker for the next irradiation time period (the following tests are the same).

[0062] The UV shielding capability of the UV shielding film is determined by (A) t Compare the changes in the / A0)% value, A0 and A t The absorbance at 554 nm represents the original RhB solution and the RhB solution irradiated with ultraviolet light under film protection, respectively.

[0063] As can be seen from the test results of the above embodiments ( Figure 4 The UV absorber prepared by this invention not only has good dispersibility in polymer substrates, but also has a wide UV shielding band and excellent shielding performance. By adjusting the content of the UV shielding agent and the thickness of the film, effective UV shielding can be achieved. It can be used as a UV shielding additive in polymer substrates for outdoor use or some special locations.

Claims

1. A method for preparing an ultraviolet shielding composite material, characterized in that, The synthesis steps include the following: (1) Dissolve cerium nitrate in water, slowly add NH3·H2O, and adjust the pH of the solution to ≈6; (2) Dissolve bismuth ammonium citrate and sodium sulfide in water of the same volume as in step (1) and mix thoroughly; (3) The solution in step (2) is mixed with the solution in step (1), and added to a polytetrafluoroethylene high-pressure reactor and kept at 170°C for 12 hours. The product is filtered, washed, dried, and ground to obtain nano-cerium oxide / bismuth sulfide composite material. (4) The nano-cerium oxide / bismuth sulfide composite material dissolves in an ethanol aqueous solution and is uniformly dispersed by ultrasonication; (5) 3,4-Dihydroxybenzoate ethyl ester is dissolved in an ethanol aqueous solution of the same volume as in step (4); (6) The dispersion from step (4) was mixed with the solution from step (5), the pH was adjusted to approximately 6 with acetic acid, and the reaction was carried out at 50°C for 10 hours. The product was then centrifuged, washed, dried, and ground to obtain the UV shielding composite material. The molar ratio of bismuth sulfide to cerium oxide (mol / mol) is (3-5):1, and the molar ratio of sodium sulfide to bismuth ammonium citrate (mol / mol) is 3:2; The structure of the ultraviolet shielding composite material is that cerium oxide and bismuth sulfide exist in a uniformly dispersed manner, and ethyl 3,4-dihydroxybenzoate is coated on the surface of the composite.

2. The method for preparing the ultraviolet shielding composite material according to claim 1, characterized in that, The molar volume ratio (mmol:mL) of cerium nitrate to water is 1:

50.

3. The method for preparing the ultraviolet shielding composite material according to claim 1, characterized in that, The mass ratio (g / g) of nano-cerium oxide / bismuth sulfide composite material and ethyl 3,4-dihydroxybenzoate is 1:0.

8.

4. The method for preparing the ultraviolet shielding composite material according to claim 1, characterized in that, The drying temperature in step (3) is 80-100℃.

5. The method for preparing the ultraviolet shielding composite material according to claim 1, characterized in that, The drying temperature in step (6) is 60-80°C.

6. The method for preparing the ultraviolet shielding composite material according to claim 1, characterized in that, The ethanol-water solution has an ethanol to water volume ratio (mL / mL) of 1:

9.

7. The method for preparing the ultraviolet shielding composite material according to claim 1, characterized in that, In step (4), the mass-to-volume ratio (g / mL) of the nano-cerium oxide / bismuth sulfide composite material and the ethanol aqueous solution is 1:30.

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