A UV shielding agent based on nano-cerium oxide and its preparation method

Abstract

This invention discloses a UV shielding agent based on nano-cerium oxide and its preparation method, belonging to the field of polymer materials technology. The synthesis method involves coating and modifying the surface of nano-cerium oxide (CeO2) with 3-aminopropyltriethoxysiloxane (KH550) to prepare CeO2@SiO2-NH2. The grafting of silicon-oxygen bonds onto the nano-CeO2 surface enhances its shielding ability as a UV absorber. The amino groups on the surface undergo an addition-dehydration reaction with the aldehyde groups of cinnamaldehyde, introducing a large π-bond conjugated system including C=N, C=C, and benzene rings. This not only improves the poor dispersion of nanoparticles but also achieves a synergistic enhancement of UV shielding performance. By adding the prepared UV shielding composite material to PVC, the results of PVC film testing show that the modified nano-CeO2 significantly improves the dispersibility and UV resistance of the PVC film.

Description

Technical Field

[0001] This invention belongs to the field of polymer material applications, specifically relating to a UV shielding agent based on nano-cerium oxide and its preparation method. The preparation steps are as follows:

[0002] Background Technology

[0003] Some inorganic metal oxide nanoparticles can effectively avoid ultraviolet (UV) damage by reflecting and scattering UV light. However, when these nanoparticles are directly blended with polymers to form films, they are prone to aggregation and uneven distribution. Therefore, modifying the surface of nanoparticles to improve their dispersibility in polymer materials has become a key research focus.

[0004] Small-molecule organic UV absorbers are inexpensive, readily available, and highly compatible with polymers. However, they are prone to migration during prolonged use, at high temperatures, or in contact with solvents. Achieving both the stability of small-molecule organic UV absorbers and the excellent UV shielding capabilities of inorganic nanoparticles is a crucial approach to obtaining ideal UV shielding materials. Summary of the Invention

[0005] In view of the shortcomings and deficiencies of the existing technology, the primary objective of this invention is to provide an ultraviolet shielding composite material and its preparation method, so as to obtain an ultraviolet shielding material with strong ultraviolet shielding ability and the excellent properties of both inorganic and organic small molecule ultraviolet shielding agents.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A UV shielding agent based on nano-cerium oxide and its preparation method, comprising the following synthesis steps:

[0008] (1) Nano CeO2 was dissolved in anhydrous ethanol, ultrasonically dispersed, and 3-aminopropyltriethoxysiloxane (KH550) was added. After complete mixing, the mixture was kept at 80℃ for 12 h, centrifuged, washed, and dried to obtain the product (CeO2@SiO2-NH2).

[0009] (2) Weigh CeO2@SiO2-NH2 and dissolve it in anhydrous ethanol. Disperse it evenly by ultrasonication. Add an appropriate amount of cinnamaldehyde (CMA) to the dispersion and react at 50°C for 4 hours. Centrifuge, wash, and dry to obtain a UV shielding agent based on nano-cerium oxide (CeO2@SiO2-CMA).

[0010] Preferably, the mass-to-volume ratio of nano-CeO2 to anhydrous ethanol is 1 g:(120-160) mL.

[0011] Preferably, the mass-to-volume ratio of nano-CeO2 and KH550 is 1g:10mL, and the particle size range of CeO2 is (20-80)nm.

[0012] As a preferred embodiment, the mass-to-volume ratio of CeO2@SiO2-NH2 to anhydrous ethanol is 1 g:(160-200) mL.

[0013] Preferably, the mass ratio of CeO2@SiO2-NH2 to CMA is 1g:(0.8~1.2)g.

[0014] Preferably, the drying temperature in step (1) is (80-100)℃, and the drying temperature in step (2) is (60-80)℃.

[0015] Preferably, the detergent is an aqueous solution of ethanol at a volume ratio of 1:1, and the water used in the experiment is self-made deionized water.

[0016] The UV shielding agent (CeO2@SiO2-CMA) obtained in step (2) is ultrasonically dispersed in a solvent that dissolves the substrate, and then mixed with a polymer solution at room temperature. The mixture is ultrasonically dispersed until uniform to obtain a film-forming solution.

[0017] After degassing the film-forming solution, it is cast onto a plate to form a film, left to stand in the air to solidify, vacuum dried to constant weight, and then peeled off to obtain an ultraviolet shielding film. The plate is a glass plate.

[0018] The nano-CeO2@SiO2-CMA composite material prepared by the method of this invention not only possesses UV shielding properties enhanced by CeO2, SiO2 and CMA, but also exhibits good dispersibility in a polymer matrix, thus better leveraging the synergistic enhancement of the organic / inorganic composite UV shielding agent.

[0019] The method of this invention has the advantages of inexpensive and readily available materials and simple operation. Attached Figure Description

[0020] Figure 1 The infrared spectra of CeO2@SiO2-NH2 prepared in Example 1, and S3 and CeO2 prepared in Example 3 are shown.

[0021] Figure 2 The XRD pattern of S3 was prepared for Example 3.

[0022] Figure 3 The UV shielding performance of different particle (2%) / PVC composite films.

[0023] Figure 4 Comparison of UV absorption curves of Rhodamine B solution after 120 min of UV irradiation under the protection of S3 / PVC composite film of different concentrations. Detailed Implementation

[0024] The present invention will be further described below with reference to embodiments, but is not limited thereto.

[0025] It should be noted that, unless otherwise specified, the materials involved in the embodiments of the present invention are all publicly known and available for purchase, and the particle size of nano-cerium oxide is (30±10nm).

[0026] Example 1

[0027] 1. Dissolve 0.8g CeO2 in 100mL anhydrous ethanol, add 8mL KH550 dropwise, disperse completely by ultrasonication at room temperature, keep the reaction at 80℃ for 12h, centrifuge, wash with ethanol-water solution, and dry at 80℃ for 12h to obtain the product (CeO2@SiO2-NH2, denoted as A).

[0028] 1. Dissolve 0.5g of A in 80mL of anhydrous ethanol and disperse it evenly by ultrasonication. Add 0.4g of CMA, keep the reaction at 50℃ for 4h, centrifuge, wash with ethanol-water solution, and dry completely at 80℃ to obtain CeO2@SiO2-g-CMA particles (denoted as S1).

[0029] Example 2

[0030] 2. Dissolve 0.5g of A in 80mL of anhydrous ethanol and disperse it evenly by ultrasonication. Add 0.5g of CMA, keep the reaction at 50℃ for 4h, centrifuge, wash with ethanol-water solution, and dry completely at 80℃ to obtain CeO2@SiO2-g-CMA particles (denoted as S2).

[0031] Example 3

[0032] 3. Dissolve 0.5g of A in 80mL of anhydrous ethanol and disperse it evenly by ultrasonication. Add 0.6g of CMA, keep the reaction at 50℃ for 4h, centrifuge, wash with ethanol-water solution, and dry at 80℃ for 12h to obtain CeO2@SiO2-g-CMA particles (denoted as S3).

[0033] Example 4

[0034] Preparation of composite film (using PVC as substrate).

[0035] Under stirring conditions, 0.8g of PVC powder was slowly added in batches to 10mL of DMF, and after slight heating, it was stirred and dispersed evenly.

[0036] Weigh out the specified amount of nanoparticles and dissolve them in 10 mL of DMF. Disperse them completely by ultrasonication, add them to the above PVC solution, and stir to obtain a uniform dispersion.

[0037] 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.

[0038] Using the same method, pure PVC films without nanoparticles were prepared and their ultraviolet shielding performance was compared.

[0039] Study on the UV shielding performance of PVC composite film.

[0040] 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.

[0041] The PVC composite film to be tested was used as an ultraviolet shielding film to cover the mouth of the beaker. The Rh B 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).

[0042] 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.

[0043] As can be seen from the test results of the above embodiments ( Figure 3 The UV absorber prepared by this invention provides excellent UV shielding performance for polymer substrate films. 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 agent based on nano-cerium oxide, characterized in that, The synthesis steps include the following: (1) Nano-cerium oxide was dissolved in anhydrous ethanol, ultrasonically dispersed, and 3-aminopropyltriethoxysiloxane was added. After complete mixing, the mixture was kept at 80°C for 12 hours. After centrifugation, washing, and drying, the product CeO2@SiO2-NH2 was obtained. (2) Weigh CeO2@SiO2-NH2 and dissolve it in anhydrous ethanol. Disperse it evenly by ultrasonication. Add cinnamaldehyde to the dispersion and react at 50°C for 4 hours. Centrifuge, wash, and dry to obtain a UV shielding agent based on nano-cerium oxide. The particle size range of nano-cerium oxide is 20–80 nm; In step (2), the mass ratio of CeO2@SiO2-NH2 to cinnamaldehyde is 1 g : (0.8-1.2) g; In step (1), the mass-to-volume ratio of nano-cerium oxide and 3-aminopropyltriethoxysiloxane is 1 g: 10 mL.

2. The method for preparing an ultraviolet shielding agent based on nano-cerium oxide according to claim 1, characterized in that, In step (1), the mass-to-volume ratio of nano-cerium oxide and anhydrous ethanol is 1 g: (120-160) mL.

3. The method for preparing an ultraviolet shielding agent based on nano-cerium oxide according to claim 1, characterized in that, In step (2), the mass-to-volume ratio of CeO2@SiO2-NH2 to anhydrous ethanol is 1 g: (160-200) mL.

4. The method for preparing an ultraviolet shielding agent based on nano-cerium oxide according to claim 1, characterized in that, The drying temperature in step (1) is 80-100℃, and the drying temperature in step (2) is 60-80℃.

5. The method for preparing an ultraviolet shielding agent based on nano-cerium oxide according to claim 1, characterized in that, The detergent in steps (1) and (2) is an ethanol-water solution with a volume ratio of 1:1, and the water used in the experiment is deionized water.

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