Composite microwave absorbing materials with ultraviolet shielding function and their preparation methods

Abstract

This invention discloses a composite microwave absorbing material with ultraviolet (UV) shielding function and its preparation method. The steps of the composite material preparation method are as follows: S1: Zinc source, titanium source, and urea are reacted in water. After the reaction, the mixture is cooled, centrifuged, washed, and dried to obtain zinc-titanium bimetallic hydroxide Zn / Ti-LDH; S2: The Zn / Ti-LDH from S1 is dispersed in N,N-dimethylformamide, and then cerium source, iron source, and 2-aminoterephthalic acid are added. After the reaction, the mixture is cooled, centrifuged, washed, and dried to obtain a bimetallic-organic framework composite Zn / Ti-LDH@Ce / Fe-MOF; S3: Zn / Ti-LDH@Ce / Fe-MOF and sodium dodecylbenzenesulfonate are dispersed in water, and pyrrole and ammonium persulfate are added to react, thus obtaining a composite microwave absorbing material with UV shielding function. The composite material of this invention has good dispersibility in polymer materials, stable performance, and possesses both UV shielding and microwave absorption properties.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing materials technology, and in particular to composite microwave absorbing materials with ultraviolet shielding function and their preparation methods. Background Technology

[0002] Ultraviolet radiation is a high-energy spectrum in sunlight. Prolonged exposure to ultraviolet radiation can cause significant harm to organisms and also cause many polymer materials to fade, age, and lose their functionality.

[0003] Furthermore, while electronic communication technology brings convenience to humankind, it also causes serious electromagnetic pollution. High-performance microwave absorbing materials can effectively shield incident electromagnetic waves through dielectric loss, magnetic loss, and multiple scattering.

[0004] Therefore, functional materials with microwave / ultraviolet shielding properties have high practical application value, especially for outdoor and high-altitude coating materials. Currently, there is very little research on functional additives with this comprehensive property. Summary of the Invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a composite microwave absorbing material with ultraviolet shielding function and its preparation method. The composite material has good dispersibility in polymer materials, stable performance, and has ultraviolet shielding and microwave absorption properties.

[0006] The method for preparing the composite microwave absorbing material with ultraviolet shielding function proposed in this invention includes the following steps:

[0007] S1: Zinc source, titanium source and urea are reacted in water. After the reaction, the mixture is cooled, centrifuged, washed and dried to obtain zinc-titanium bimetallic hydroxide Zn / Ti-LDH.

[0008] S2: The Zn / Ti-LDH of S1 was dispersed in N,N-dimethylformamide, and then cerium source, iron source and 2-aminoterephthalic acid were added. After the reaction, the mixture was cooled, centrifuged, washed and dried to obtain the bimetallic-organic framework complex Zn / Ti-LDH@Ce / Fe-MOF.

[0009] S3: Disperse Zn / Ti-LDH@Ce / Fe-MOF and sodium dodecylbenzenesulfonate in water, and add pyrrole and ammonium persulfate to react and prepare a composite microwave absorbing material with ultraviolet shielding function.

[0010] Preferably, the zinc salt in S1 is one or more of zinc nitrate, zinc chloride, zinc sulfate, and zinc acetate; and the titanium source is one or more of titanium tetrachloride, titanium nitrate, and titanium sulfate.

[0011] Preferably, the molar ratio of zinc source, titanium source and urea in S1 is 1:0.4-0.6:10-15.

[0012] Preferably, the reaction temperature in S1 is 100-120℃ and the reaction time is 20-28h.

[0013] Preferably, the cerium source in S2 is one or more of cerium nitrate and its hydrate, cerium chloride and its hydrate, and cerium sulfate and its hydrate; the iron source is one or more of ferric nitrate, ferric chloride, and ferric sulfate.

[0014] Preferably, the molar ratio of Zn / Ti-LDH, cerium source, iron source and 2-aminoterephthalic acid in S2 is 1g:0.8-1.2mmol:8-10mmol:4-6mmol.

[0015] Preferably, the reaction temperature in S2 is 140-160℃ and the reaction time is 16-24h.

[0016] Preferably, the mass-to-volume ratio of Zn / Ti-LDH@Ce / Fe-MOF, sodium dodecylbenzenesulfonate, pyrrole, and ammonium persulfate in S3 is 1g:0.8-1.2g:6-8mL:0.5-0.7g.

[0017] Preferably, the reaction conditions in S3 are 10-14 h at room temperature.

[0018] The composite absorbing material with ultraviolet shielding function is prepared by the above method proposed in this invention.

[0019] Beneficial technical effects of the present invention:

[0020] (1) The composite material prepared by the present invention has both ultraviolet shielding and wave absorption properties, and the composite material has good dispersibility and stable performance in polymer materials.

[0021] (2) The composite material preparation method of the present invention is simple, does not require high temperature and high pressure, is highly operable, and has a wide range of raw material sources that are inexpensive and readily available.

[0022] (3) The porous structure of Ce / Fe-MOF in the composite material of the present invention helps to polarize the interface and provides more paths for the incident electromagnetic waves, increasing the probability of contact between the electromagnetic waves and the absorber, so that the electromagnetic waves are absorbed and reflected multiple times in the channels, and the energy is converted into heat and dissipated to a greater extent; on the other hand, the dielectric properties of the material can be optimized by using MOF based on adjusting the material structure, and ZnTi-LDH is conducive to achieving impedance matching, thus realizing the excellent absorption performance of the composite material; ZnTi-LDH and Ce / Fe-MOF in the composite material of the present invention have a synergistic promoting effect on ultraviolet shielding. Attached Figure Description

[0023] Figure 1 The XRD patterns of the products of Examples 1, 2 and 5 of this invention are shown below.

[0024] Figure 2 XPS image of the composite absorbing material S5 proposed in this invention;

[0025] Figure 3 Here is a SEM image of the composite microwave absorbing material S5 proposed in this invention;

[0026] Figure 4 The ultraviolet absorption spectra of the products of Examples 1-6 of this invention are shown below;

[0027] Figure 5 The ultraviolet transmission spectra of the PVA film, 1% S1 / PVA and S5 / PVA composite films with different contents proposed in this invention are shown.

[0028] Figure 6 The curve showing the attenuation constant as a function of frequency for product S1 with a filling ratio of 30 wt% in Example 1 of this invention.

[0029] Figure 7 The attenuation constant of the product S2 with a filling ratio of 30wt% in Example 2 of this invention is shown as a function of frequency.

[0030] Figure 8 The attenuation constant of product S3 with a filling ratio of 30wt% in Example 3 of this invention is shown as a function of frequency.

[0031] Figure 9 The attenuation constant of product S5 with a filling ratio of 30wt% in Example 5 of this invention is shown as a function of frequency.

[0032] Figure 10 The curve of attenuation constant versus frequency for product S6 with a filling ratio of 30wt% in Example 6 of the present invention. Detailed Implementation

[0033] The present invention will be further explained below with reference to specific embodiments.

[0034] Example 1

[0035] Dissolve 1.41 g ZnCl2, 0.6 mL TiCl4 and 7.5 g urea in 50 mL distilled water, stir to dissolve and mix evenly, transfer to an autoclave, react at 110 °C for 24 h, centrifuge, wash the solid with water several times, and dry at 80 °C for 4 h to obtain Zn / Ti-LDH (denoted as S1).

[0036] Example 2

[0037] 0.5 g Zn / Ti-LDH (S1) was added to 40 mL of DMF and ultrasonically mixed until homogeneous. Then, 0.22 g Ce(NO3)3·6H2O, 0.73 g FeCl3, and 0.45 g NH2-BDC were added, stirred until dissolved and mixed evenly, transferred to a high-pressure reactor, and reacted at 150 °C for 20 h. After cooling to room temperature, the mixture was centrifuged, washed with DMF and ethanol respectively, and dried to obtain Zn / Ti-LDH@Ce / Fe-MOF (denoted as S2).

[0038] Example 3

[0039] 0.22g Ce(NO3)3·6H2O, 0.73g FeCl3 and 0.45g NH2-BDC were stirred to dissolve and mix evenly. The mixture was then transferred to a high-pressure reactor and reacted at 150℃ for 20h. After cooling to room temperature, the mixture was centrifuged, washed with DMF and ethanol respectively, and dried to obtain Ce / Fe-MOF (denoted as S3).

[0040] Example 4

[0041] Mix 0.3g Zn / Ti-LDH@Ce / Fe-MOF powder (S2), 0.3g sodium dodecylbenzenesulfonate (SDBS) and 100mL water, and ultrasonically disperse the mixture until homogeneous. Place the mixture in an ice bath, add 1.5mL pyrrole to the solution, and continue stirring for 60min.

[0042] 0.52 mL of pyrrole and 1.7 g of APS were added in portions to the above solution under stirring at room temperature, and the reaction was stirred continuously for 12 h. After centrifugation, the product was washed with water and ethanol respectively, and dried at 60 °C for 24 h to obtain the product Zn / Ti-LDH@Ce / Fe-MOF@PPy1 (denoted as S4).

[0043] Example 5

[0044] Mix 0.3g Zn / Ti-LDH@Ce / Fe-MOF powder (S2), 0.3g (SDBS) and 100mL water, disperse and mix evenly by ultrasonication, place the mixture in an ice bath, add 2.5mL pyrrole to the above solution, and continue stirring for 60min;

[0045] 0.52 mL of pyrrole and 1.7 g of APS were added in portions to the above solution under stirring at room temperature, and the reaction was stirred continuously for 12 h. After centrifugation, the product was washed with water and ethanol respectively, and dried at 60 °C for 24 h to obtain the product Zn / Ti-LDH@Ce / Fe-MOF@PPy2 (product designated as S5).

[0046] Example 6

[0047] Mix 0.3g Zn / Ti-LDH@Ce / Fe-MOF powder (S2), 0.3g (SDBS) and 100mL deionized water, and ultrasonically disperse and mix evenly. Place the mixture in an ice bath, add 3.5mL pyrrole to the above solution, and continue stirring for 60min.

[0048] 0.52 mL of pyrrole and 1.7 g of APS were added in portions to the above solution under stirring at room temperature, and the reaction was stirred continuously for 12 h. After centrifugation, the product was washed with deionized water and ethanol, respectively, and dried at 60 °C for 24 h to obtain the product Zn / Ti-LDH@Ce / Fe-MOF@PPy3 (denoted as S6).

[0049] Example 7

[0050] Preparation of composite film (taking polyvinyl alcohol (PVA) as the substrate as an example): 0.8g of PVA powder was slowly added to 10mL of water under stirring conditions and stirred to disperse evenly; the composite material was dissolved in 10mL of water, ultrasonically dispersed evenly, added to the above PVA solution, ultrasonically stirred to form a uniform dispersion, the dispersion was cast into a film on a plate, allowed to stand in the air to form a film, vacuum dried to constant weight, and peeled off to obtain an ultraviolet shielding film.

[0051] 0.8g of PVA powder was slowly added to 20mL of water and stirred until evenly dispersed. The same method was used to prepare a PVA film without nanoparticles.

[0052] The XRD patterns of the products from Examples 1, 2, and 5 are shown below. Figure 1 The 2θ values ​​of S1 spectrum (24.15°, 28.11°, 31.15°, 32.86°, 36.08°, 58.19°, and 59.41°) correspond to the positions of the (006), (012), (100), (101), (009), (110), and (113) crystal planes of Zn / Ti-LDH, respectively. The 2θ values ​​of S2 spectrum (10.9°, 16.8°, 20.6°, 29.7°, 49.3°, and 54.9°) correspond to the positions of the (220), (400), (333), (444), (775), and (531) crystal planes of UiO-66-NH2, respectively. As can be seen from the S5 spectrum, the crystal structure of Zn / Ti-LDH@Ce / Fe-MOF after encapsulating polypyrrole remains unchanged, but due to the amorphous nature of pyrrole, the intensity of some characteristic peaks decreases.

[0053] Figure 2 XPS analysis of product S5 from Example 5 confirmed the presence of C, N, O, Zn, Fe, Ti, and Ce elements in the sample.

[0054] Figure 3For example, the SEM image of product S5 shows that S5 exhibits uniform microspheres, and the polypyrrole coating successfully encapsulates Zn / Ti-LDH@Ce / Fe-MOF.

[0055] Figure 4 The images show the UV spectra of products S1-S6 from Examples 1-6. It can be seen from the images that Zn / Ti-LDH contributes to the UV absorption performance of Ce / Fe-MOF, and the UV absorption performance is further enhanced after encapsulating polypyrrole.

[0056] Figure 5 The transmittance spectra of PVA and its composite films in the wavelength range of 200-600nm are shown in the figure. It can be seen from the figure that the transmittance of the PVA composite film with S5 content of 1.5% in this wavelength range is less than 10%, which means it has strong UV shielding performance.

[0057] Paraffin wax was pressed into a coaxial sample with an outer diameter of 7.00 mm, an inner diameter of 3.04 mm, and a thickness of about 2 mm in a special mold at a mass ratio of 3:7. The electromagnetic parameters were tested using an AV3629D vector network analyzer, and the wave absorption performance was calculated. The test frequency range was 2-18 GHz. Figures 6-10 The figures show the reflection loss curves of different products in the examples as a function of frequency in the range of 2-18 GHz. Among them, S5 exhibits the best microwave absorption capability. When the coating thickness is 3.0 mm, the maximum absorption intensity reaches -46.2 dB at 14.8 GHz.

Claims

1. A method for preparing a composite microwave absorbing material with ultraviolet shielding function, characterized in that, The steps are as follows: S1: Zinc source, titanium source and urea are reacted in water. After the reaction, the mixture is cooled, centrifuged, washed and dried to obtain zinc-titanium bimetallic hydroxide Zn / Ti-LDH. S2: The Zn / Ti-LDH of S1 was dispersed in N,N-dimethylformamide, and then cerium source, iron source and 2-aminoterephthalic acid were added. After the reaction, the mixture was cooled, centrifuged, washed and dried to obtain the bimetallic-organic framework complex Zn / Ti-LDH@Ce / Fe-MOF. S3: Disperse Zn / Ti-LDH@Ce / Fe-MOF and sodium dodecylbenzenesulfonate in water, and add pyrrole and ammonium persulfate to react and prepare a composite microwave absorbing material with ultraviolet shielding function.

2. The method for preparing the composite microwave absorbing material with ultraviolet shielding function according to claim 1, characterized in that, In S1, the zinc salt is one or more of zinc nitrate, zinc chloride, zinc sulfate, and zinc acetate; the titanium source is one or more of titanium tetrachloride, titanium nitrate, and titanium sulfate.

3. The method for preparing the composite microwave absorbing material with ultraviolet shielding function according to claim 1, characterized in that, The molar ratio of zinc source, titanium source and urea in S1 is 1:0.4-0.6:10-15.

4. The method for preparing the composite microwave absorbing material with ultraviolet shielding function according to claim 1, characterized in that, The reaction in S1 is carried out at a temperature of 100-120℃ for 20-28 hours.

5. The method for preparing the composite microwave absorbing material with ultraviolet shielding function according to claim 1, characterized in that, In S2, the cerium source is one or more of cerium nitrate and its hydrate, cerium chloride and its hydrate, and cerium sulfate and its hydrate; the iron source is one or more of ferric nitrate, ferric chloride, and ferric sulfate.

6. The method for preparing the composite microwave absorbing material with ultraviolet shielding function according to claim 1, characterized in that, The molar ratio of Zn / Ti-LDH, cerium source, iron source and 2-aminoterephthalic acid in S2 is 1g:0.8-1.2mmol:8-10mmol:4-6mmol.

7. The method for preparing the composite microwave absorbing material with ultraviolet shielding function according to claim 1, characterized in that, The reaction in S2 takes place at a temperature of 140-160℃ for 16-24 hours.

8. The method for preparing the composite microwave absorbing material with ultraviolet shielding function according to claim 1, characterized in that, The mass-to-volume ratio of Zn / Ti-LDH@Ce / Fe-MOF, sodium dodecylbenzenesulfonate, pyrrole, and ammonium persulfate in S3 is 1g:0.8-1.2g:6-8mL:0.5-0.7g.

9. The method for preparing the composite microwave absorbing material with ultraviolet shielding function according to claim 1, characterized in that, The reaction conditions in S3 are 10-14 h at room temperature.

10. A composite microwave absorbing material with ultraviolet shielding function prepared by the method according to any one of claims 1-9.

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