A dead paint polymerization catalyst, its preparation method and application

Abstract

The application discloses a dead paint polymerization catalyst and a preparation method and application thereof, relates to preparation of iron-based metal-organic framework materials (Fe-MOFs) and research on catalytic dead paint polymerization performance of the Fe-MOFs, and belongs to the field of natural high polymer materials. H2BDC and a metal iron salt are dissolved in N,N-dimethylformamide, and MIL-101(Fe) with an inwardly concave octahedral morphology is prepared through a solvothermal method. The MIL-101(Fe) is added into dead paint liquid, and after being uniformly mixed, is coated on a tinplate. The dead paint liquid with the catalyst can be dried in 8 hours, while the dead paint liquid without the catalyst is still not surface-dried after 1440 hours, indicating that the Fe-MOFs have a remarkable catalytic effect on film formation of the dead paint, and the flexibility and impact resistance of the dead paint film obtained are remarkably improved. The application solves the problem that the dead paint cannot be cured due to inactivation of the paint enzyme, and has a simple and easy preparation method, a green and environment-friendly preparation process and a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of natural polymer materials, and specifically relates to a method for preparing a MIL-101(Fe) catalyst with an inwardly concave octahedral morphology and its application in catalyzing the polymerization of dead paint into a film. Background Technology

[0002] Natural lacquer, also known as "Chinese lacquer" or "large lacquer," is a natural coating with excellent comprehensive properties. It is a pure, natural, milky-white liquid secreted by the lacquer tree. Upon contact with oxygen, its color gradually turns brown, and its surface gradually hardens into a film. Raw lacquer forms a film through laccase-catalyzed polymerization. Once formed, the lacquer film exhibits excellent acid resistance, heat resistance, abrasion resistance, and corrosion resistance, with superior comprehensive properties unmatched by other synthetic coatings. However, it also has some drawbacks. For example, raw lacquer is sensitizing and requires specific conditions (relative humidity not lower than 80%, temperature 20-30℃) to solidify into a film. Its high viscosity makes it difficult to apply. These drawbacks limit the widespread application and promotion of raw lacquer as a coating. Furthermore, improper storage or prolonged storage can lead to laccase inactivation, turning the lacquer into "dead lacquer" that cannot naturally solidify into a film. Dead lacquer, unable to dry naturally, is used to extract urushiol, a process that requires large amounts of organic solvents, causing environmental pollution and wasting raw lacquer resources.

[0003] In recent years, metal-organic frameworks (MOFs) have attracted increasing attention from research teams. MOFs are crystals with periodic network structures formed by the self-assembly of organic ligands and inorganic metal ions. They possess extremely high porosity, ultra-large specific surface area, and ordered pore structure, leading to their wide applications in sensing, adsorption, drug delivery, and gas storage. The diversity of the types and coordination modes of the linkers and metals composing MOFs endows them with high modulus and customizability, providing more possibilities for their application in the catalytic polymerization of dead lacquer. Currently, Fe-MOFs are considered the most promising photocatalysts due to their excellent visible light harvesting ability and highly dispersed iron active sites (photocatalytic reactions only occur upon contact with a light source). However, no research or patent literature has been found on using Fe-MOFs to catalyze the polymerization of raw or dead lacquer or to improve lacquer film performance.

[0004] Therefore, this invention prepares Fe-MOFs catalysts via a solvothermal method and applies them to the catalytic polymerization reaction of dead lacquer, which is expected to solve the problem of dead lacquer being unable to solidify due to laccase deactivation and has broad application prospects. Summary of the Invention

[0005] The purpose of this invention is to improve the problems existing in the application of raw lacquer, mainly addressing the problem that dead lacquer cannot be cured due to laccase deactivation. This invention provides a dead lacquer polymerization catalyst, its preparation method and application, which utilizes the catalytic effect of Fe-MOFs catalyst to improve the drying performance of raw lacquer and restore the curing activity of dead lacquer.

[0006] This invention is implemented through the following technical solution:

[0007] A dead paint polymerization catalyst is a Fe-MOF material MIL-101(Fe) with an inwardly concave octahedral morphology.

[0008] The catalyst is prepared by dissolving FeCl3·6H2O and H2BDC in DMF solution. After complete dissolution, the DMF solution containing H2BDC is added dropwise to the DMF solution containing FeCl3·6H2O. The mixture is sonicated for 5-10 minutes, and the resulting mixed solution is reacted in an oven at 110°C for 24 hours. After natural cooling to room temperature, the reactants are washed and purified sequentially with DMF and methanol solutions. The product is extracted by centrifugation and filtration, and then treated under vacuum at 80-120°C for 8 hours. The final collected product is MIL-101(Fe).

[0009] Furthermore, the molar ratio of FeCl3·6H2O to H2BDC is n(FeCl3·6H2O) / n(H2BDC) = 2:1, 1:1, or 1:2.

[0010] The present invention also provides the application of the aforementioned dead paint polymerization catalyst in catalyzing dead paint film formation.

[0011] In practical applications, a certain amount of Fe-MOF catalyst is uniformly dispersed in dead paint liquid, coated, and dried at room temperature to obtain the paint film.

[0012] Furthermore, the solid content of the dead paint is 80%-95%.

[0013] Furthermore, the amount of Fe-MOFs catalyst added is 0.5wt%-10wt% of the dead paint.

[0014] Furthermore, the method for uniform dispersion is stirring, homogenization, or ball milling.

[0015] Furthermore, the coating is made by applying a uniformly mixed catalyst / dead paint onto a tinplate sheet.

[0016] The beneficial effects of this invention are as follows:

[0017] 1) The research results show that the dead paint solution with the catalyst can achieve complete drying within 8 hours, while the dead paint solution without the catalyst still has not dried after 1440 hours. This indicates that MIL-101(Fe), with its concave octahedral morphology, has a significant catalytic effect on the film formation of dead paint. The catalyst provided by this invention can restore the curing activity of dead paint under the premise of laccase inactivation, significantly shorten the time required for dead paint to cure and form a film, and improve the physical and mechanical properties of the paint film. It is expected to solve the problem of dead paint failing to cure due to laccase inactivation.

[0018] 2) The MIL-101(Fe) catalyst synthesized in this invention has a high specific surface area and porosity, as well as a unique concave octahedral morphology, which is beneficial to reducing electron conduction resistance and improving the transfer efficiency of water and oxygen at the interface. Furthermore, the metal unsaturated coordination sites in the structure can directly accept electrons from urushiol as Lewis acidic sites and promote the formation and transformation of quinone transition states, which is beneficial to improving the catalytic polymerization rate of dead lacquer.

[0019] 3) The preparation method used in this invention is simple and easy to implement. The preparation process is green and environmentally friendly. Moreover, the catalytic process does not require an additional xenon lamp as a light source and can be carried out at room temperature, which has broad application prospects.

[0020] This invention is the first to apply Fe-MOFs materials to the catalytic polymerization reaction of dead paint, which not only expands the application field of MOFs materials, but also provides an experimental basis for the utilization of dead paint resources. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Figure 1 The XRD patterns of the MIL-101(Fe) samples prepared in Examples 1-3 and Comparative Example 1 of this invention are shown.

[0023] Figure 2 Infrared spectra of MIL-101(Fe) samples prepared in Examples 1-3 and Comparative Example 1 of this invention;

[0024] Figure 3 These are scanning electron microscope (SEM) images of the MIL-101(Fe) samples prepared in Examples 1-3 and Comparative Example 1 of this invention. Figure 3 In the diagram, a represents MIL-101(Fe)-1, b represents MIL-101(Fe)-2, c represents MIL-101(Fe)-3, and d represents MIL-101(Fe)-4.

[0025] Figure 4 Images of dead paint polymerization at room temperature in Example 3 and Comparative Example 2 of this invention. Figure 4 In the text, A represents Comparative Example 2, and B represents Example 3. Detailed Implementation

[0026] This invention proposes a catalyst for the polymerization of dead paint with a special morphology, its preparation method, and its application. The following detailed description, with reference to specific embodiments, illustrates the MIL-101(Fe) catalyst provided by this invention and its application in catalyzing the polymerization of dead paint.

[0027] Example 1

[0028] 2.025 g FeCl3·6H2O and 2.472 g H2BDC were dissolved separately in 30 mL of DMF solution. After complete dissolution, the DMF solution containing H2BDC was added dropwise to the DMF solution containing FeCl3·6H2O. The mixture was sonicated for 5 minutes, and then reacted in an oven at 110 °C for 24 h. After natural cooling to room temperature, the mixture was purified five times with DMF and methanol solutions, respectively. The collected product was then treated under vacuum at 100 °C for 8 h, and the final product was MIL-101(Fe)-1.

[0029] Example 2

[0030] 1.013 g FeCl3·6H2O and 0.618 g H2BDC were dissolved separately in 30 mL of DMF solution. After complete dissolution, the DMF solution containing H2BDC was added dropwise to the DMF solution containing FeCl3·6H2O. The mixture was sonicated for 5 minutes, and then reacted in an oven at 110 °C for 24 h. After naturally cooling to room temperature, the mixture was purified five times with DMF and methanol solutions, respectively. The collected product was then treated under vacuum at 100 °C for 8 h, and the final product was MIL-101(Fe)-2.

[0031] Example 3

[0032] 2.025 g of FeCl3·6H2O and 0.618 g of H2BDC were dissolved in 30 mL of DMF solution respectively. After complete dissolution, the DMF solution containing H2BDC was added dropwise to the DMF solution containing FeCl3·6H2O. The mixture was sonicated for 5 minutes, and the resulting mixture was reacted in an oven at 110 °C for 24 h. After natural cooling to room temperature, the mixture was purified five times with DMF and methanol solutions respectively. The collected product was treated under vacuum at 100 °C for 8 h, and the final product was designated as MIL-101(Fe)-3.

[0033] Comparative Example 1

[0034] 2.025 g FeCl3·6H2O and 0.618 g H2BDC were mixed and dissolved in 60 mL DMF solution. The mixture was sonicated for 5 minutes until completely dissolved, and then reacted in an oven at 110 °C for 20 h. After natural cooling to room temperature, the mixture was purified five times with DMF and methanol solutions, respectively. The collected product was then treated under vacuum at 100 °C for 8 h. The final product was the conventional MIL-101(Fe)-4.

[0035] Figure 1 The XRD patterns of the MIL-101(Fe) samples prepared in Examples 1-3 and Comparative Example 1 of this invention are shown. It can be observed from the figures that the main diffraction peaks of the four materials are generally consistent. The diffraction peak shape of sample MIL-101(Fe)-1 is poor, while the diffraction peak shapes of samples MIL-101(Fe)-2, MIL-101(Fe)-3, and MIL-101(Fe)-4 are better, and there are no impurity peaks, indicating that pure MIL-101(Fe) can be successfully synthesized using this method.

[0036] Figure 2 The infrared spectra of the MIL-101(Fe) samples prepared in Examples 1-3 and Comparative Example 1 of this invention are located at 748 cm⁻¹. –1 and 551cm –1 The characteristic absorption peaks at 1656, 1596, and 1394 cm⁻¹ are attributed to the stretching vibrations of the C–H and Fe–O bonds in MIL-101(Fe). –1 The characteristic absorption peaks at the point are attributed to the bending vibration, asymmetric vibration, and symmetric stretching vibration of C=O, respectively. This result is basically consistent with the literature reports, indicating that pure MIL-101(Fe) has been synthesized.

[0037] Figure 3 Scanning electron microscope (SEM) images of the MIL-101(Fe) samples prepared in Examples 1-3 and Comparative Example 1 of this invention. As can be seen from the images, when n(Fe) 3+ ) / n(BDC 2-When the molar ratio is 1:2, MIL-101(Fe)-1 is blocky with no special morphology. When the molar ratio increases to 1:1, the morphology of the MIL-101(Fe)-2 sample gradually tends to be a regular octahedron. Further increasing the molar ratio to 2:1, the MIL-101(Fe)-3 sample has uniform particle size and exhibits an inwardly concave octahedral morphology. This structure exposes more active sites, which is beneficial for improving the catalytic polymerization effect of dead paint. According to the literature, traditional MIL-101(Fe) is usually a solid nanoparticle, which is not conducive to the participation of active sites inside the bulk phase in the reaction. The MIL-101(Fe)-4 sample synthesized in Comparative Example 1 exhibits an irregular blocky shape, which may be related to the short reaction time and incomplete crystal growth. Taking all factors into consideration, we chose the MIL-101(Fe)-3 catalyst for the study of dead paint catalytic polymerization.

[0038] Application of Example 3

[0039] Weigh 0.1g of MIL-101(Fe)-3 catalyst and 10g of dead paint, mix them evenly at room temperature, apply the mixed paint solution to a tinplate sheet with a thickness of 75μm using a coating applicator, and dry at room temperature to obtain a paint film.

[0040] Comparative Example 2

[0041] Without adding MIL-101(Fe) catalyst, weigh 10g of dead paint and apply it to a tinplate sheet with a coating tool to a thickness of 75μm. Observe its curing at room temperature.

[0042] The physical and mechanical properties of the paint film were tested according to the following national standards: drying time GB / T1728-2020, impact resistance GB / T 1732-2020, pencil hardness GB / T 6739-2006, adhesion GB / T 9286-2021, flexibility GB / T1731-2020, and gloss GB / T 1743-1979. The test results of Comparative Example 2 and Example 3 are listed in Table 1.

[0043] Figure 4 Images show the polymerization of dead paint at room temperature in Example 3 and Comparative Example 2 of this invention. In Comparative Example 2, the dead paint remained liquid after 1440 hours. Figure 4 (A) This also proves that dead paint cannot naturally cure into a film at room temperature. However, after adding the MIL-101(Fe)-3 catalyst, the dead paint polymerizes into a film within 8 hours, and the resulting film is brown (A). Figure 4 (See section B). This result indicates that the Fe-MOFs catalyst synthesized in this invention can restore the curing activity of dead lacquer, significantly shorten the time required for dead lacquer to cure and form a film, and is expected to solve the problem of dead lacquer being unable to cure due to laccase inactivation.

[0044] Table 1 shows the drying time and physical and mechanical properties of the paint film in Example 3 and Comparative Example 2 of this invention.

[0045] Table 1. Drying time and physical and mechanical properties test results of the paint film

[0046]

[0047] As shown in Table 1, the surface drying time of the dead paint film in Example 3 was 6.5 h, and the actual drying time was 8 h. In contrast, the dead paint solution in Comparative Example 2 without catalyst did not show surface drying even after 1440 h at room temperature. This is because the laccase in the dead paint is deactivated, thus preventing it from solidifying into a film. This experimental result is consistent with literature reports. The MIL-101(Fe) catalyst prepared in this invention can catalyze the solidification of dead paint into a film, and the catalytic effect is significant, greatly shortening the polymerization time of the dead paint.

[0048] To further compare the conventional physical and mechanical properties of the comparative and examples, we placed the dead paint in an oven and thermo-cured it to obtain a completely dried dead paint film. Table 1 shows that the dead paint film polymerized using the MIL-101(Fe) catalyst had a flexibility of 0.5 mm, and its resistance to normal and reverse impacts was 55 kg·cm and 40 kg·cm, respectively. These properties were superior to those of the thermo-cured dead paint film (flexibility of 10 mm, and resistance to normal and reverse impacts of 10 kg·cm and 5 kg·cm, respectively). These results indicate that using the MIL-101(Fe) catalyst to catalyze the polymerization of dead paint into a film is significantly effective, and the flexibility and impact resistance of the film are significantly increased.

[0049] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A catalyst for the polymerization of dead paint, characterized in that: The catalyst is MIL-101(Fe), and the catalyst has an inwardly concave octahedral morphology; The preparation method of the dead paint polymerization catalyst is as follows: FeCl3·6H2O is used as the iron source and H2BDC is used as the ligand, which are dissolved in DMF solvent respectively. Then, the DMF solution containing H2BDC is added dropwise to the DMF solution containing FeCl3·6H2O and mixed. The MIL-101(Fe) catalyst is synthesized by solvothermal method.

2. A method for preparing the dead paint polymerization catalyst as described in claim 1, characterized in that: Using FeCl3·6H2O as the iron source and H2BDC as the ligand, both were dissolved in DMF solvent. Then, the DMF solution containing H2BDC was added dropwise to the DMF solution containing FeCl3·6H2O and mixed. The MIL-101(Fe) catalyst was synthesized by solvothermal method.

3. The method for preparing the dead paint polymerization catalyst according to claim 2, characterized in that: FeCl3·6H2O and H2BDC were dissolved separately in DMF solution. After complete dissolution, the DMF solution containing H2BDC was added dropwise to the DMF solution containing FeCl3·6H2O. The mixture was sonicated for 5-10 minutes, and the resulting mixed solution was reacted in an oven at 110 °C for 24 h. After natural cooling to room temperature, the reactants were washed and purified sequentially with DMF and methanol solutions. The product was extracted by centrifugation and filtration, and then treated under vacuum at 80-120 °C for 8 h. The final collected product was MIL-101(Fe).

4. The method for preparing the dead paint polymerization catalyst as described in claim 3, characterized in that: The molar ratio of FeCl3·6H2O and H2BDC is: n (FeCl3·6H2O) / n (H2BDC)=2:1-1:

2.

5. The application of the dead paint polymerization catalyst as described in claim 1 in catalyzing dead paint film formation.

6. The application according to claim 5, characterized in that: The catalyst is uniformly dispersed in the dead paint liquid, coated, and dried at room temperature to obtain the paint film.

7. The application according to claim 6, characterized in that: The solid content of the dead paint liquid is 80%-95%.

8. The application according to claim 6, characterized in that: The method of uniform dispersion is either stirring or ball milling.

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