阅读说明：本技术 一种复合超分子结构PPN@LDHs的紫外阻隔材料的制备方法 (Preparation method of ultraviolet barrier material with PPN @ LDHs composite supermolecular structure ) 是由 林彦军 王彬霞 刘闻笛 李凯涛 张玉红 王钧 赵冠翔 周鑫 于 2020-12-20 设计创作，主要内容包括：本发明公开了一种复合超分子结构PPN@LDHs的紫外阻隔材料的制备方法。该方法以硝酸根插层水滑石为前驱体,经过一步吸附酚酞后再加入絮凝剂进行包覆制得。制备过程中通过控制在pH＝8-13的碱性条件下来调节吸附在水滑石上面的酚酞向醌式结构方向转变；絮凝剂包覆可以稳定吸附的酚酞及维持其醌式结构。将本发明制备的紫外阻隔材料应用在沥青等材料中,能够明显提高其抗紫外辐射老化能力,是一类性能优异的紫外阻隔材料和添加剂。(The invention discloses a preparation method of an ultraviolet barrier material with a composite supermolecular structure PPN @ LDHs. The method takes nitrate radical intercalated hydrotalcite as a precursor, and is prepared by adding a flocculating agent for coating after phenolphthalein is adsorbed by one step. During the preparation process, the conversion of phenolphthalein adsorbed on hydrotalcite to quinoid structure is adjusted by controlling the alkaline condition of pH 8-13; the flocculant coats phenolphthalein which can be stably adsorbed and maintains its quinoid structure. The ultraviolet barrier material prepared by the invention is applied to materials such as asphalt and the like, can obviously improve the ultraviolet radiation aging resistance, and is an ultraviolet barrier material and an additive with excellent performance.)

1. A preparation method of a PPN @ LDHs ultraviolet barrier material with a composite supermolecular structure is characterized by comprising the following specific steps:

a. preparing a mixed salt solution of soluble divalent nitrate and soluble trivalent nitrate; preparing NaOH and NaNO₃The mixed alkali solution of (1), wherein NaOH and NaNO₃The molar ratio of (A) is 0.6-10; carrying out ultrasonic treatment on the mixed salt solution and the mixed alkali solution for 5-30 min;

b. dropwise adding the mixed salt solution and the mixed alkali solution into a four-neck flask simultaneously under the nitrogen atmosphere, rapidly stirring, crystallizing after dropwise adding, and finally washing, filtering and drying to obtain nitrate radical intercalated hydrotalcite;

c. preparing a mixed solution of phenolphthalein and NaOH, adding a dispersion liquid of nitrate radical intercalated hydrotalcite, stirring for adsorption, filtering, washing and then dispersing again;

d. c, adding a flocculating agent into the dispersion liquid obtained in the step c for surface coating, shaking and settling for 0.5-6 hours, filtering and drying to obtain the ultraviolet barrier material of the PPN @ LDHs with the composite supermolecular structure; and c, the mass ratio of the flocculating agent to the hydrotalcite in the dispersion liquid obtained in the step c is 0.2-2.0.

2. The method according to claim 1, wherein the solvent used in the specific step is CO removal₂And (4) later deionized water.

3. The preparation method according to claim 1, wherein the soluble divalent nitrate is selected from one or two of zinc nitrate, calcium nitrate, cobalt nitrate and nickel nitrate; the soluble trivalent nitrate is selected from one or two of ferric nitrate, aluminum nitrate and chromium nitrate.

4. The method according to claim 1, wherein the molar ratio of the divalent metal ion to the trivalent metal ion in the mixed salt solution is 1.0 to 3.5, and the concentration of the divalent metal ion is 0.5 to 1.5 mol/L.

5. The preparation method of claim 1, wherein the temperature in the step b is controlled to be 40-120 ℃, the pH of the mixed solution in the four-neck flask is 9-12, and the crystallization time is 4-24 h.

6. The preparation method according to claim 1, wherein the molar ratio of phenolphthalein to NaOH in step c is 0.1-3, and the mass ratio of phenolphthalein to nitrate radical intercalated hydrotalcite is 0.6-5; controlling the pH value of the mixed solution to be 8-13, the adsorption temperature to be 20-80 ℃, and the adsorption time to be 1-12 hours.

7. The method of claim 1, wherein the flocculating agent is a polymeric material having hydrogen bonding.

8. The preparation method according to claim 1, wherein the flocculating agent is one or more of polyacrylamide, quaternized polyacrylamide, polyacrylic acid, sodium polyacrylate and polyethylene oxide.

9. The method as claimed in claim 1, wherein the nitrate intercalated hydrotalcite prepared in step b has a specific surface area of 100-200m²/g。

10. Use of the uv-blocking material of composite supramolecular structures PPN @ LDHs prepared by the method according to any one of claims 1-9 as uv-resistant additive in asphalt, plastic, rubber materials.

The technical field is as follows:

the invention belongs to the technical field of preparation of inorganic functional materials, and particularly relates to a preparation method of an ultraviolet barrier material with a composite supermolecular structure PPN @ LDHs.

Background art:

with further research and application of ultraviolet light, it was found that proper ultraviolet irradiation is beneficial to human body and activities and biological activities of ecosystem, but excessive ultraviolet irradiation easily degrades organic compounds, which is disadvantageous to organic-containing building materials, such as asphalt, rubber, plastics, etc., which are often greatly shortened in life and reduced in durability due to ultraviolet aging. This problem seriously affects the normal activities of human beings, increases the material reparation and labor costs, and is a concern and attention of many scholars. In order to reduce the effect of ultraviolet radiation on human activities, it is necessary to develop highly efficient ultraviolet absorbers. Phenolphthalein (Phenolphthalein) molecular formula is C₂₀H₁₄O₄PPN is a common solution acid-base indicator, and research shows that PPN has excellent ultraviolet absorption capacity in a wave band of 220-310 nm. However, the valence and structure of PPN are changed due to the change of pH environment, namely, divalent ions of PPN exist in the balance of lactone structure and quinoid structure, and the application of PPN is limited by the isomerization of complex valence structures. Hydrotalcite (LDHs) is used as an inorganic supermolecular structural functional material, has the properties of adjustable chemical composition of a main layer plate, amphiphilicity of acid and alkali and the like, and can be used as a stabilizer to be added into a high molecular material.

The invention content is as follows:

the invention aims to provide a simple and efficient preparation method of an ultraviolet barrier material with a composite supermolecular structure PPN @ LDHs. The method takes nitrate radical hydrotalcite as a precursor, and is prepared by adding a flocculating agent for coating after phenolphthalein is adsorbed by one step. During the preparation process, the conversion of the adsorbed phenolphthalein to the quinoid structure is adjusted by controlling the hydrotalcite in the alkaline pH range of 8-13; the flocculant coats phenolphthalein which can be stably adsorbed and maintains the pH value of the surface. The prepared ultraviolet barrier material is applied to materials such as asphalt and the like, can obviously improve the ultraviolet radiation aging resistance, and is an ultraviolet barrier material and an additive with excellent performance.

The preparation method of the ultraviolet barrier material with the composite supermolecular structure PPN @ LDHs comprises the following steps:

a. preparing a mixed salt solution of soluble divalent nitrate and soluble trivalent nitrate; preparing NaOH and NaNO₃The mixed alkali solution of (1), wherein NaOH and NaNO₃The molar ratio of (A) is 0.6-10; carrying out ultrasonic treatment on the mixed salt solution and the mixed alkali solution for 5-30 min;

b. dropwise adding the mixed salt solution and the mixed alkali solution into a four-neck flask simultaneously under the nitrogen atmosphere, rapidly stirring, crystallizing after dropwise adding, and finally washing, filtering and drying to obtain nitrate radical intercalated hydrotalcite;

c. preparing a mixed solution of phenolphthalein and NaOH, adding a dispersion liquid of nitrate radical intercalated hydrotalcite, stirring for adsorption, filtering, washing and then dispersing again;

d. c, adding a flocculating agent into the dispersion liquid obtained in the step c for surface coating, shaking and settling for 0.5-6 hours, filtering and drying to obtain the ultraviolet barrier material of the PPN @ LDHs with the composite supermolecular structure; and c, the mass ratio of the flocculating agent to the hydrotalcite in the dispersion liquid obtained in the step c is 0.2-2.0.

The solvent used in the above step is CO removal₂And (4) later deionized water.

The soluble divalent nitrate is selected from one or two of zinc nitrate, calcium nitrate, cobalt nitrate and nickel nitrate; the soluble trivalent nitrate is selected from one or two of ferric nitrate, aluminum nitrate and chromium nitrate.

The molar ratio of the divalent metal ions to the trivalent metal ions in the mixed salt solution is 1.0-3.5, and the concentration of the divalent metal ions is 0.5-1.5 mol/L.

In the step b, the temperature is controlled to be 40-120 ℃, the pH value of the mixed solution in the four-neck flask is 9-12, and the crystallization time is 4-24 h.

In the step c, the molar ratio of phenolphthalein to NaOH is 0.1-3, and the mass ratio of phenolphthalein to nitrate radical intercalated hydrotalcite is 0.6-5; controlling the pH value of the mixed solution to be 8-13, the adsorption temperature to be 20-80 ℃, and the adsorption time to be 1-12 hours.

The flocculant is a polymeric material with hydrogen bonds. In particular to one or more of polyacrylamide, quaternized polyacrylamide, polyacrylic acid, sodium polyacrylate and polyethylene oxide.

The specific surface area of the nitrate radical intercalated hydrotalcite prepared in the step b is 100-200m²/g。

The ultraviolet barrier material with the composite supermolecular structure PPN @ LDHs prepared by the method is applied as an ultraviolet resistant additive in asphalt, plastics and rubber materials.

The invention has the beneficial effects that:

(1) the ultraviolet barrier material prepared by directly adsorbing phenolphthalein by using the hydrotalcite is simpler and more practical in synthesis method and lower in cost compared with the intercalation synthesis method, and provides possibility for large-scale application.

(2) According to the ultraviolet barrier material prepared by the invention, phenolphthalein is adsorbed on hydrotalcite, and a stable composite quinoid structure is formed under a specific alkaline environment, so that a stronger conjugation effect is generated, and the ultraviolet absorption capacity of PPN is enhanced. The ultraviolet barrier material integrates the specific two-dimensional barrier effect of hydrotalcite and the ultraviolet absorption capacity of phenolphthalein, greatly improves the ultraviolet barrier capacity of the composite material, and widens the application range of the ultraviolet barrier material as an ultraviolet barrier agent.

(3) The hydrotalcite in the ultraviolet barrier material prepared by the invention has high specific surface area, and the adsorption quantity of phenolphthalein is obviously improved, so that the ultraviolet barrier property of the composite material is enhanced.

(4) The invention adopts the flocculating agent for coating, so that the adsorbed phenolphthalein is in a quinoid structure and stably exists, and the ultraviolet absorption capacity and the stability of the material are greatly improved.

Description of the drawings:

FIG. 1 shows CaAl-NO prepared in example 1₃XRD pattern of LDH.

FIG. 2 shows CaAl-NO prepared in example 1₃SEM picture of-LDH.

FIG. 3 is a thermogravimetric difference spectrum of the UV-blocking material PPN @ CaAl-LDH prepared in example 1.

FIG. 4 is an ultraviolet absorption spectrum of the ultraviolet barrier material PPN @ CaAl-LDH prepared in example 1.

FIG. 5 is a thermogravimetric difference spectrum of PPN @ CoAl-LDH prepared in example 2.

FIG. 6 is a UV absorption spectrum of PPN @ CoAl-LDH prepared in example 2.

The specific implementation mode is as follows:

the invention will now be further described, but should not be construed as limiting the scope of the invention. The solvents used in the following experiments were all ultrapure water, i.e., ultrapure water for CO removal₂And (4) later deionized water.

Example 1:

1) in a molar ratio of n (Ca)²⁺):n(Al³⁺) 37.52g of Al (NO) was weighed out in a ratio of 2:1, respectively₃)₃﹒9H₂O(0.5M)、47.23g Ca(NO₃)₂﹒4H₂Dissolving O (1M) medicine in 200mL of ultrapure water, and marking as a mixed solution X; 19.20g NaOH (2.4M) and 17.00g NaNO were weighed₃(1M) was dissolved in 200mL of ultrapure water and designated as mixed solution Y. The mixed solution X, Y was treated with ultrasound for 10 min. And under the protection of nitrogen atmosphere, dropwise adding the mixed solution X, Y into the four-neck flask simultaneously, rapidly stirring, controlling the mixing temperature at 60 ℃, maintaining the pH at 9, and crystallizing for 6 hours to obtain hydrotalcite slurry. Washing, filtering and drying to obtain CaAl-NO₃-LDH hydrotalcite powder. The crystal structure of the product is characterized by adopting an X-ray powder diffractometer, and an obvious layered diffraction peak is shown (figure 1); the morphology was characterized by SEM and showed flower-like morphology with a large specific surface area (FIG. 2), BET specific surface area of 114m²/g。

2) 7.96g (0.025mol) of phenolphthalein and 1.20g (0.03mol) of NaOH were weighed out and dissolved in 100ml of ultrapure water, and the solution was recorded as phenolphthalein solution with rapid stirring.

3) Weighing 2g of CaAl-NO₃dispersing-LDH hydrotalcite powder in 200mL of ultrapure water, adding 20mL of phenolphthalein solution, and uniformly mixing. And (2) placing the mixed solution in a constant-temperature water bath at 30 ℃ for stirring for 2h, taking out, washing, dispersing in 200mL of ultrapure water again, adding 0.5g of polyacrylamide, shaking for 1h, filtering, and drying to obtain the PPN @ CaAl-LDH composite ultraviolet barrier material.

The results of thermogravimetric differential thermal analysis (TG-DSC) of the PPN @ CaAl-LDH composite ultraviolet barrier material prepared above are shown in fig. 3, in which the oxidative combustion of PPN corresponds to the second step, indicating that a large amount of PPN is adsorbed on the surface of LDHs. The ultraviolet reflection curve measured by the ultraviolet-visible analysis method is shown in FIG. 4, and the composite material has strong absorption capacity to ultraviolet rays in the wavelength range of 220-440nm as shown in FIG. 4.

Weighing 50g of asphalt (BN), heating to enable the asphalt to be in a viscous liquid state, adding the PPN @ CaAl-LDH composite ultraviolet barrier material according to the mass fraction of 2%, and mixing for 2h by using a high-speed shearing mixer to obtain the PPN @ LDHs/BN. The blank was processed in the same manner. BN, PPN @ LDHs/BN is placed in an ultraviolet aging instrument for aging irradiation (the experimental conditions are that the irradiation temperature is 60 ℃, and the ultraviolet irradiation power is 1.2W/m²) The irradiation was continued for 5 days without interruption. After testing, the samples added with PPN @ LDHs/BN have smaller changes of viscosity and softening point, which indicates that the asphalt added with PPN @ LDHs has better stability.

Example 2:

1) 37.52g of Al (NO) are weighed out₃)₃﹒9H₂O(0.5M)、58.21g Co(NO₃)₂﹒6H₂Dissolving O (1M) medicine in 200mL of ultrapure water, and marking as a mixed solution X; 24.00g NaOH (3M), 17.00g NaNO were weighed₃(1M) was dissolved in 200mL of ultrapure water and designated as mixed solution Y. The mixed solution X, Y was treated with ultrasound for 10 min. Under the protection of nitrogen atmosphere, the mixed solution X, Y is added into a four-neck flask drop by drop at the same time, the mixture is rapidly stirred, the mixing temperature is controlled at 60 ℃, the pH value is controlled at 9, and the hydrotalcite slurry is obtained after crystallization is finished at 60 ℃ for 6 hours. Washing, filtering and drying to obtain the CoAl-LDH hydrotalcite powder.

2) Phenolphthalein solution was prepared in the same manner as in example 1.

3) The hydrotalcite was adsorbed with phenolphthalein and the subsequent flocculation operation was performed in the same manner as in example 1 to obtain the PPN @ CoAl-layered double hydroxide (CoAl-LDH) ultraviolet barrier material.

The above description is only directed to the preferred embodiments of the present invention, and various modifications and improvements on the basis of the above method will be apparent to those skilled in the art, and are intended to be included within the scope of the present invention.