Bio-based azobenzene compound as well as preparation method and application thereof
By using bio-based azobenzene compounds as photo-switching functional agents in biodegradable materials, and by utilizing alternating infrared and ultraviolet light irradiation to achieve dynamic regulation of the material's surface properties, the problem of poor ink wetting and adhesion caused by the surface inertness of biodegradable materials is solved, resulting in highly efficient printing effects.
Patent Information
- Application Number
- CN202511757620.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-02-24
AI Technical Summary
The surface inertness of existing biodegradable materials results in inks failing to wet, low adhesion, and poor printing quality. Existing improvement methods are not durable, have poor uniformity, and are costly.
Bio-based azobenzene compounds are used as photo-switching functional agents. The surface properties of the material are dynamically regulated by alternating infrared and ultraviolet light irradiation. The intramolecular charge transfer effect of the D-π-A asymmetric structure is utilized to isomerize and change the surface properties of the material to improve ink wettability and adhesion.
It significantly improves the ink wettability and adhesion of biodegradable materials, maintains the stability of materials under visible light, and fixes the ink by UV curing to achieve a long-lasting printing effect.
Smart Images
Figure CN121554460A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of bio-based material functional agents, to the copolymerization technology of biodegradable materials, and in particular to a bio-based azobenzene compound, its preparation method and application. Background Technology
[0002] Fully biodegradable materials have become an important alternative to traditional petroleum-based plastics. However, their surface inertness and low surface energy, leading to problems such as ink non-wetting, poor adhesion, and poor printing results, severely restrict their widespread adoption and application. Currently, only surface treatment is available to improve these materials, including two main categories: physical methods such as corona treatment and flame treatment, and chemical methods involving surface coating with ink to bind the base oil. Physical methods are not durable, have poor uniformity, and damage the material itself; chemical methods require different base oils for different printing inks, have complex production processes, high costs, and significantly reduce the biodegradability of the base material after surface coating with the base oil.
[0003] A search revealed that while patent literature in the field of photo-switching functional agents has some disclosure, there are significant differences in chemical structure and chemical bond activity between these technologies and the copolymerization technology of biodegradable materials used in this invention application. This results in either poor final material activity, making it difficult to copolymerize with ink active molecules under light, or strong activity, leading to poor directionality in the reaction process.
[0004] Therefore, developing a functional additive derived from biomass that is fully biodegradable and can persistently improve the printability of bio-based materials is an urgent problem to be solved. Summary of the Invention
[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, it provides a bio-based azobenzene compound and its preparation method, and also provides the application of the compound as a photo-switching functional agent in ultraviolet curing printing of bio-based materials.
[0006] The technical solution of this invention is: A bio-based azobenzene compound with the following chemical formula: The functional group R1-N=N is a strong electron-donating group of biomass, derived from bio-based amines, including 4-benzyloxy-3-methoxyaniline or 4-acetoxy-3,5-dimethoxyaniline.
[0007] The preparation of the above-mentioned bio-based azobenzene compounds includes the following steps: The bio-based amine was dissolved in a mixture of dilute hydrochloric acid, water, and tetrahydrofuran. Sodium nitrite aqueous solution was slowly added dropwise while stirring. After the addition was complete, the mixture was stirred rapidly for 30 to 50 minutes. The entire process was carried out at a constant temperature of 0 to 5°C using an ice-salt bath to obtain the first solution. The ratio of bio-based amine, tetrahydrofuran, water, dilute hydrochloric acid, and sodium nitrite aqueous solution was (0.9 to 1): (2 to 3): (2 to 3): (8 to 10): 2, g / mL. 2-Aminothiophene-5-carboxaldehyde was dissolved in a mixture of ethanol and water, with sodium acetate added as a buffer. The ratio of 2-aminothiophene-5-carboxaldehyde, ethanol, water, and sodium acetate was (6~7): (100~150): (100~150): (9~10), g / mL / mL / g. The solution was cooled to 5-10°C to obtain a second solution. Under light-protected and rapid stirring, the first solution was slowly added dropwise to the second solution. After the addition was complete, the solution was allowed to rise naturally to room temperature and then stirred rapidly for 2-3 hours. The solution was then filtered, and the solid was washed with a mixture of ethanol and water to obtain vanillin-azo-aminothiophene. The obtained vanillin-azo-aminothiophene was dissolved in anhydrous ethanol, and piperidine and glacial acetic acid were added for catalytic reaction. The mixture was heated to 70-90°C and reacted for 5-8 hours. After the reaction was completed by TLC monitoring, the mixture was cooled and filtered. The resulting solid was dissolved in a mixed solvent of tetrahydrofuran and ethanol, and the catalyst was added. The mixture was stirred at room temperature for 8 hours under hydrogen protection. After TLC showed that the deprotection was completed, the catalyst was removed by filtration, the filtrate was concentrated, and the resulting solid was recrystallized from ethanol to obtain a bio-based azobenzene compound photoswitching functional agent.
[0008] Moreover, in step (1), the concentration of the dilute hydrochloric acid is 0.1 mol / L.
[0009] Moreover, in step (1), the concentration of the sodium nitrite aqueous solution is 10 wt%.
[0010] Moreover, in step (4), the weight ratio of vanillin-azo-aminothiophene to rhodanine is 3 to 4:1.
[0011] Moreover, in step (4), the catalyst is a palladium on carbon (Pd / C) catalyst with a palladium loading of 10%.
[0012] The present invention also provides a method for using the above-mentioned bio-based azobenzene compound as a photo-switching functional agent in the ultraviolet curing printing process, comprising the following steps: uniformly mixing the bio-based azobenzene compound photo-switching functional agent with biomass materials and excipients and processing it into the desired workpiece; first irradiating the surface of the material with infrared light, and then printing the desired pattern with an ultraviolet curing offset printing machine to obtain the finished product.
[0013] Moreover, the biomass material is polylactic acid, polyhydroxyalkanoate, or polycaprolactone, all of which are commercially available products.
[0014] Moreover, the excipients include lubricants, nucleating agents, plasticizers, calcium carbonate, and titanium dioxide, all of which are commercially available products.
[0015] Furthermore, the infrared light wavelength is 750~1000nm, and the ultraviolet light wavelength is 300~400nm.
[0016] The azobenzene compound molecule provided by this invention is composed of a strong electron-donating group (Donor, D), a π-conjugated system of azobenzene (-N=N-), and a strong electron-withdrawing group (Acceptor, A). This D-π-A asymmetric structure forms a huge intramolecular charge transfer (ICT) effect within the molecule, redshifting the maximum absorption peak of this azobenzene compound molecule to the near-infrared region of 800-900 nm. It has the characteristic of dynamically changing the surface properties of the material through isomerization by infrared light irradiation.
[0017] The azobenzene compound molecules provided by this invention are in a low-energy, linear trans configuration under visible light irradiation, exhibiting the bulk properties of the material and maintaining stability. When irradiated with infrared light, the azobenzene compound molecules rotate to a higher-energy, bent cis configuration, increasing the surface polarity and tension of the material, which is beneficial for ink wetting. When irradiated with ultraviolet light, the molecules in the ink begin to polymerize, and these active components also interact with the contacting high-energy azobenzene compound molecules and are fixed on the material surface, significantly improving ink adhesion. The azobenzene compound molecules in the blank parts not covered by ink revert from the cis configuration to the initial trans configuration, and the material recovers its original properties and remains stable. Attached Figure Description
[0018] Figure 1 The top figure shows the NMR spectrum of the bio-based azobenzene compound obtained in Example 1, and the bottom figure shows the NMR spectrum of the bio-based azobenzene compound obtained in Example 2.
[0019] Figure 2 The left figure shows the UV-Vis-NIR absorption spectrum of the bio-based azobenzene compound prepared in Example 1 before near-infrared light irradiation, and the right figure shows the UV-Vis-NIR absorption spectrum of the bio-based azobenzene compound prepared in Example 1 after near-infrared light irradiation.
[0020] Figure 3 The left figure shows the UV-Vis-NIR absorption spectrum of the bio-based azobenzene compound prepared in Example 2 before near-infrared light irradiation, and the right figure shows the UV-Vis-NIR absorption spectrum of the bio-based azobenzene compound prepared in Example 2 after near-infrared light irradiation.
[0021] Figure 4 Images show the milky white sheet prepared in Example 3 and the residues after composting in Comparative Examples 1-3 for 58 days.
[0022] Figure 5 The images show the printing effects of the milky white sheet prepared in Example 3 and the milky white sheets prepared in Comparative Examples 1-3.
[0023] Figure 6 The image shows the effect of ink adhesion testing using the cross-cut adhesion test on the milky white sheet prepared in Example 3 and the milky white sheets prepared in Comparative Examples 1-3. Detailed Implementation
[0024] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. The following embodiments are merely descriptive and not limiting, and the scope of protection of the present invention is not limited thereto. Example
[0025] A method for preparing an azobenzene compound, comprising the following steps: Set up a three-necked flask equipped with an ice-salt bath and a stirrer. Set the stirring speed to 50 rpm and control the material temperature to 0~5℃. Add 25 mL of water, 25 mL of tetrahydrofuran, 100 mL of 0.1 mol / L dilute hydrochloric acid, and 10 g of 4-benzyloxy-3-methoxyaniline in sequence. Then increase the stirring speed to 200 rpm and slowly add 20 mL of 10 wt% sodium nitrite aqueous solution. After completion, continue stirring for 30 minutes to obtain the first solution.
[0026] Set up a separate three-necked flask with a stirrer, set the stirring speed to 50 rpm, and add 150 mL of water, 150 mL of ethanol and 6.5 g of 2-aminothiophene-5-carboxaldehyde in sequence and stir until homogeneous. Then add 10 g of sodium acetate and cool to 5-10°C to obtain the second solution.
[0027] Under light-protected and rapidly stirred conditions, the first solution was slowly added dropwise to the second solution. After the addition was complete, the mixture was allowed to rise naturally to room temperature and then rapidly stirred for 2 hours before filtration. The resulting solid was washed with a mixture of 50 mL ethanol and 50 mL water to obtain vanillin-azo-aminothiophene.
[0028] 15g of the prepared vanillin-azo-aminothiophene and 5g of rhodanine were dissolved in anhydrous ethanol. Rhodanine is a strong electron-withdrawing group in the compound, which can greatly reduce the energy required for charge transfer. When the molecule absorbs light energy, electrons can more easily flow from the electron-donating end (Donor) to the electron-withdrawing end (Acceptor) through a π-bridge. Specifically, the absorption wavelength of the compound molecule will shift towards longer wavelengths (i.e., redshift), requiring specific conditions (infrared irradiation) for excitation, thus improving the excitation characteristics of ordinary azo compounds in the visible light range. This allows the compound to be applied to biodegradable materials while maintaining the basic properties of the biodegradable materials in the visible light range. 0.25 mL of piperidine and 0.12 mL of glacial acetic acid were added. The mixture was heated to 80°C and reacted for 6 hours. After the reaction was monitored by TLC, the mixture was cooled and filtered. The resulting solid was dissolved in 50 mL of tetrahydrofuran and 50 mL of ethanol. Then, 1.7 g of palladium-on-carbon catalyst with a 10% palladium loading was added. The mixture was stirred at room temperature for 8 hours under hydrogen protection. After TLC showed that deprotection was complete, the palladium-on-carbon catalyst was removed by filtration through a diatomaceous earth pad. The filtrate was concentrated to one-third of its original volume and cooled in an ice-water bath. A dark solid with a metallic luster precipitated out. This solid was recrystallized from ethanol to obtain a bio-based azobenzene compound. Example
[0029] A method for preparing an azobenzene compound, wherein some raw materials and amounts differ from those in Example 1, specifically as follows: In the first solution, 10g of 4-benzyloxy-3-methoxyaniline was replaced with 9.8g of 4-acetoxy-3,5-dimethoxyaniline. The remaining substances were: 20mL water, 20mL tetrahydrofuran, 80mL 0.1mol / L dilute hydrochloric acid, and 20mL 10wt% sodium nitrite aqueous solution. The amounts of each substance in the second solution are: 100 mL water, 100 mL ethanol, 6 g 2-aminothiophene-5-carboxaldehyde, and 9 g sodium acetate. In the final synthesis, 15g of vanillin-azo-aminothiophene and 4g of rhodanine were obtained, and the amounts and preparation methods of the remaining substances were the same as in Example 1.
[0030] The NMR spectra of the bio-based azobenzene compound photoswitching functional agents prepared in Examples 1 and 2 are as follows: Figure 1 As shown, where Figure 1 The above figure shows the NMR spectrum of the bio-based azobenzene compound obtained in Example 1. Figure 1 The figure below shows the NMR spectrum of the bio-based azobenzene compound obtained in Example 2. Figure 1 It can be seen that the corresponding azobenzene compounds were successfully synthesized in this invention.
[0031] The ultraviolet-visible-near-infrared absorption spectra of the bio-based azobenzene compound prepared in Example 1 before and after infrared irradiation are shown below. Figure 2 As shown, the left figure is the UV-Vis-NIR absorption spectrum of the bio-based azobenzene compound prepared in the example before near-infrared light irradiation, and the right figure is the UV-Vis-NIR absorption spectrum of the bio-based azobenzene compound prepared in Example 1 after near-infrared light irradiation.
[0032] The UV-Vis-NIR absorption spectra of the bio-based azobenzene compound prepared in Example 2 before and after infrared irradiation are as follows: Figure 3 As shown, the left figure is the UV-Vis-NIR absorption spectrum of the bio-based azobenzene compound prepared in Example 2 before near-infrared light irradiation, and the right figure is the UV-Vis-NIR absorption spectrum of the bio-based azobenzene compound prepared in Example 2 after near-infrared light irradiation.
[0033] Depend on Figure 2 and Figure 3 It is known that the azobenzene compound of this invention can effectively complete a reversible photo-induced isomerization reaction under infrared light irradiation. Under visible light irradiation, it is in a low-energy, linear trans configuration, exhibiting the bulk properties and remaining stable. When irradiated with infrared light, the azobenzene compound molecules rotate to a higher-energy, bent cis configuration, increasing the surface polarity and tension of the material, which is beneficial for ink wetting. When irradiated with ultraviolet light, the molecules in the ink begin to polymerize. These active components also interact with the contacting high-energy azobenzene compound molecules and are fixed on the material surface, significantly improving ink adhesion. The azobenzene compound molecules in the blank parts not covered by ink revert from the cis configuration to the initial trans configuration, and the material recovers its original properties and remains stable. Example
[0034] 2.5g of the bio-based azobenzene compound obtained in Example 1, 450g of polylactic acid resin powder (purchased from Henan Jindan Lactic Acid Technology Co., Ltd.), 5g of lubricant, 0.5g of nucleating agent, 1.8g of plasticizer, 25g of calcium carbonate, and 25g of titanium dioxide were processed into 0.18mm thick milky white sheets using a twin-screw three-roll calender (Guangdong Xihua Machinery Co., Ltd. XH-432). Except for the bio-based azobenzene compound, the other biomass materials and auxiliary materials were commercially available. The synthesis process was also a conventional operation with no special requirements, and the mixing and pressing process was the same as that of Comparative Examples 1 to 3.
[0035] Comparative Example 1 Take 450g of polylactic acid resin powder, 5g of lubricant, 0.5g of nucleating agent, 1.8g of plasticizer, 25g of calcium carbonate, and 25g of titanium dioxide, and process them into a 0.18mm thick milky white sheet using a twin-screw three-roll calender.
[0036] Comparative Example 2 Take 450g of polylactic acid resin powder, 5g of lubricant, 0.5g of nucleating agent, 1.8g of plasticizer, 25g of calcium carbonate, and 25g of titanium dioxide. Use a twin-screw three-roll calender to make a milky white sheet with a thickness of 0.18mm. The surface of the sheet is corona treated with a plasma generator (Shenzhen Nann Technology Co., Ltd. NE-ATR02).
[0037] Comparative Example 3 Take 450g of polylactic acid resin powder, 5g of lubricant, 0.5g of nucleating agent, 1.8g of plasticizer, 25g of calcium carbonate, and 25g of titanium dioxide, and process them into a 0.18mm thick milky white sheet using a twin-screw three-roll calender. Coat the surface of the sheet with an ink bonding primer (3M Company, USA).
[0038] The biodegradability of Examples 3 and Comparative Examples 1-3, i.e., the biodegradation rate after 58 days under composting conditions, was determined according to GB / T 19277. The results are shown in Table 1. The residue after 58 days of composting is as follows: Figure 4 As shown in Table 1 and Figure 4 It can be seen that Example 3 has higher biodegradability compared to Comparative Examples 1-3.
[0039] Table 1 Comparison of Biodegradation Rates Serial Number Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Biodegradation rate 96.8 93.4 81.1 12.5 Example 3: The surface was first irradiated with 808nm wavelength infrared light, and then a test pattern was printed using a printing press (Komori SPICA426, Japan, ultraviolet wavelength 395nm). Comparative Examples 1-3: The test patterns were printed directly using the same press, and the printing results were as follows. Figure 5 As shown, by Figure 5 It can be seen that Example 3 has better printing effects such as color reproduction and resolution compared to Comparative Examples 1 to 3.
[0040] The ink adhesion of the printed patterns in Examples 3 and Comparative Examples 1-3 was tested using the cross-cut adhesion test, and the results were as follows: Figure 6 As shown, by Figure 6 It can be seen that Example 3 has better ink adhesion than Comparative Examples 1-3.
[0041] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A bio-based azobenzene compound, characterized in that: The chemical formula of the bio-based azobenzene compound is: The functional group R1-N=N is a strong electron-donating group of biomass, derived from bio-based amines, including 4-benzyloxy-3-methoxyaniline or 4-acetoxy-3,5-dimethoxyaniline.
2. A method for preparing the bio-based azobenzene compound as described in claim 1: the bio-based azobenzene compound, characterized in that: Includes the following steps: The bio-based amine was dissolved in a mixture of dilute hydrochloric acid, water and tetrahydrofuran. Sodium nitrite aqueous solution was slowly added dropwise while stirring. After the addition was complete, the mixture was stirred rapidly for 30 to 50 minutes. The entire process was carried out at a constant temperature of 0 to 5°C using an ice-salt bath to obtain the first solution. 2-Aminothiophene-5-carboxaldehyde was dissolved in a mixture of ethanol and water, sodium acetate was added as a buffer, and the solution was cooled to 5-10°C to obtain a second solution. Under light-protected and rapid stirring, the first solution was slowly added dropwise to the second solution. After the addition was complete, the solution was allowed to rise naturally to room temperature and then stirred rapidly for 2-3 hours. The solution was then filtered, and the solid was washed with a mixture of ethanol and water to obtain vanillin-azo-aminothiophene. The obtained vanillin-azo-aminothiophene and rhodanine were dissolved in anhydrous ethanol, and piperidine and glacial acetic acid were added for catalytic reaction. The reaction was heated to 70-90°C for 5-8 hours. After the reaction was completed by TLC monitoring, the temperature was lowered and the mixture was filtered. The obtained solid was dissolved in a mixed solvent of tetrahydrofuran and ethanol, and the catalyst was added. The mixture was stirred at room temperature for 8 hours under hydrogen protection. After TLC showed that the deprotection was completed, the catalyst was removed by filtration, the filtrate was concentrated, and the obtained solid was recrystallized from ethanol to obtain the bio-based azobenzene compound.
3. The method for preparing the above-mentioned bio-based azobenzene compound according to claim 2, characterized in that: In step (1), the ratio of the amount of bio-based amine, dilute hydrochloric acid, water and tetrahydrofuran and sodium nitrite aqueous solution is: (0.9~1):(2~3):(2~3):(8~10):2, g / mL / mL / mL / mL.
4. The method for preparing the above-mentioned bio-based azobenzene compound according to claim 2, characterized in that: In step (2), the ratio of 2-aminothiophene-5-carboxaldehyde, ethanol, water and sodium acetate is (6~7): (100~150): (100~150): (9~10), g / mL / mL / g.
5. The method for preparing the above-mentioned bio-based azobenzene compound according to claim 2, characterized in that: In step (4), the weight ratio of vanillin-azo-aminothiophene to rhodanine is 3 to 4:
1.
6. The method for preparing the above-mentioned bio-based azobenzene compound according to claim 2, characterized in that: In step (4), the catalyst is a palladium on carbon (Pd / C) catalyst with a palladium loading of 10%.
7. An application of a bio-based azobenzene compound as a photoswitching functional agent, characterized in that: Includes the following steps: In the ultraviolet curing printing process, the bio-based azobenzene compound photo-switching functional agent described in claim 1 is uniformly mixed with biomass materials and excipients and then processed into the desired workpiece. The surface of the material is first irradiated with infrared light, and then the desired pattern is printed using an ultraviolet curing offset printing machine to obtain the finished product.
8. The application of bio-based azobenzene compounds as photoswitching functional agents according to claim 7 is characterized in that: The biomass material is polylactic acid, polyhydroxyalkanoate, or polycaprolactone, all of which are commercially available products.
9. The application of bio-based azobenzene compounds as photoswitching functional agents according to claim 7 is characterized in that: The excipients include lubricants, nucleating agents, plasticizers, calcium carbonate, and titanium dioxide, all of which are commercially available products.
10. The application of the bio-based azobenzene compound according to claim 7 as a photothermal conversion agent in laser etching of biomass materials, characterized in that: The infrared light wavelength is 750~1000nm, and the ultraviolet light wavelength is 300~400nm.