High-performance polyurethane adhesive constructed by bionic structure composite filler as well as preparation method and application of high-performance polyurethane adhesive

Abstract

The invention discloses a high-performance polyurethane adhesive constructed by a bionic structure composite filler as well as a preparation method and application of the high-performance polyurethane adhesive, and belongs to the technical field of polymer composite materials and wood board manufacturing. Aiming at the problems of non-uniform filler dispersion, single function and the like of the existing polyurethane adhesive, the invention innovatively develops a composite adhesive system with a three-dimensional synergistic effect. The system is prepared from the following raw materials in parts by mass: 50 parts of polydiphenylmethane diisocyanate, 100 parts of castor oil, 7-20 parts of lignin composite filler with a bionic structure and 0.05-0.1 part of a catalyst. A tannic acid modified bionic structure lignin / molybdenum disulfide composite filler is prepared through a ball-milling stripping and ultrasonic self-assembly combined method and cooperates with a castor oil cross-linked network to form a multi-interface action mechanism, so that the adhesive simultaneously realizes improvement of the bonding strength, the flame retardant property and the photothermal effect, and the ratio of bio-based components in the raw materials reaches 65% or above; the green manufacturing requirement is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer composite materials and wood board manufacturing, and particularly relates to a high-performance polyurethane adhesive constructed with bionic structure composite fillers, and a preparation method and application thereof. Background Art

[0002] Traditional polyurethane adhesives use petroleum-based polyols and isocyanates as raw materials, which rely on non-renewable resources and have high environmental costs. Bio-based alternative materials have become a research and development hotspot, among which vegetable oils have become a key research direction due to their renewability and structural designability. Castor oil is a natural hydroxyl-functionalized glyceride. The unique long-chain fatty acids in its molecular structure give polyurethane materials outstanding hydrophobic properties and biodegradability, making it easier to construct three-dimensional cross-linked systems compared to other vegetable oils. However, existing castor oil-based polyurethane adhesives have low bonding strength and lack functional properties such as flame retardancy and photothermal response, making it difficult to meet the needs of special application scenarios.

[0003] Lignin is one of the most abundant aromatic biopolymers on Earth, with high strength and modulus. Adding lignin to castor oil-based polyurethane adhesives can act as a physical cross-linking agent, enhancing the strength and stability of the adhesive. However, the low density of reactive sites in the lignin molecular structure leads to poor interfacial compatibility with the polyurethane matrix and discontinuous stress transfer paths, which greatly restricts performance enhancement. Although the reactivity of lignin can be improved through chemical modification, a microphase separation structure still exists between the modified particles and the matrix, making it impossible to construct an energy dissipation channel, causing the adhesive to exhibit brittle fracture characteristics. Therefore, how to break through the bottleneck of interfacial adhesion performance while giving the polyurethane system synergistic functions such as photothermal response is a technical problem that needs to be solved urgently in the development of bio-based polyurethane adhesive performance enhancement. Summary of the Invention

[0004] Technical Problem Solved: To address the common problems of existing polyurethane adhesive systems, such as uneven filler dispersion, limited adhesive functional properties, and unsustainable raw materials due to poor inorganic / organic interface compatibility, the present invention provides a high-performance polyurethane adhesive constructed with biomimetic structural composite fillers, as well as its preparation method and application. A multi-layered reinforcement system is constructed by combining ball milling exfoliation with ultrasonic self-assembly. Tannic acid, molybdenum disulfide, and lignin are compositely assembled to construct a reinforcing phase with a biomimetic layered structure. This system synergizes with a castor oil cross-linking network to form multiple interface interaction mechanisms, enabling the polyurethane adhesive to simultaneously improve bonding strength, flame retardancy, and photothermal effects. The present invention utilizes bio-based components in the synthetic raw materials for the polyurethane, accounting for over 65% of the total, making it environmentally friendly and sustainable, meeting green manufacturing requirements.

[0005] Technical solution: The first object of the present invention is to provide a high-performance polyurethane adhesive constructed with a bionic structure composite filler. The raw materials of the high-performance polyurethane adhesive are proportioned as follows by mass: 50 parts of polydiphenylmethane diisocyanate, 100 parts of castor oil, 7 to 20 parts of bionic structure lignin / molybdenum disulfide composite filler, and 0.05 to 0.1 parts of catalyst. The preparation method of the bionic structure lignin / molybdenum disulfide composite filler is as follows: after fully mixing tannic acid, lignin and molybdenum disulfide, deionized water is added to ensure sufficient contact of the reaction components during the ball milling process, after ball milling using a planetary ball mill, the mixture is washed with deionized water and subjected to ultrasound to achieve self-assembly of lignin / molybdenum disulfide composite filler nanosheets, and finally the bionic structure lignin / molybdenum disulfide composite filler is prepared by centrifugation and freeze-drying.

[0006] This invention utilizes tannic acid to functionalize the surfaces of molybdenum disulfide and lignin through the directional chelation of phenolic hydroxyl groups, forming highly reactive two-dimensional nanounits. Lignin's three-dimensional network structure utilizes multi-site coordination to achieve three-dimensional ordered assembly of the nanounits through π-π stacking and hydrogen bonding, creating a biomimetic lignin / molybdenum disulfide composite filler. This filler is then topologically composited with a castor oil-based polyurethane crosslinking network to create multiple interfacial interactions, enhancing the compatibility and interfacial reactivity between the lignin and polyurethane, resulting in a polyurethane adhesive with excellent bonding strength, flame retardancy, and photothermal conversion properties.

[0007] During the preparation of the biomimetic lignin / MoS2 composite filler, the high-energy collision and shear force of ball milling rupture the van der Waals bonds between the MoS2 layers. Simultaneously, tannic acid and lignin intercalate between the layers, aiding exfoliation through intercalation of phenolic hydroxyl and sulfonic acid groups. Ultrasonic cavitation is then used to further exfoliate the remaining few layers of MoS2. The directional adsorption of tannic acid and lignin drives the alternating stacking of MoS2 nanosheets, forming a structure similar to the nacre layer of a shell, thus preparing the biomimetic lignin / MoS2 composite filler.

[0008] Preferably, the castor oil has an average functionality of 2.7 and a ricinoleic acid content greater than 80%.

[0009] Preferably, the catalyst is dibutyltin dilaurate.

[0010] Preferably, the lignin is lignin sulfonate.

[0011] Preferably, the mass ratio of the tannic acid, lignin and molybdenum disulfide is 5:1:5.

[0012] Preferably, the ball milling speed is 500 rpm and the time is 36 hours.

[0013] Preferably, deionized water is added to a solid content of 15-20 wt % to ensure sufficient contact of the reaction components during the ball milling process.

[0014] The second object of the present invention is to provide a method for preparing a high-performance polyurethane adhesive constructed based on the above-mentioned bionic structure composite filler, comprising the following steps: adding vacuum-dehydrated castor oil and polydiphenylmethane diisocyanate to a reaction vessel, stirring evenly, then adding a catalyst, and continuing to stir the reaction to obtain an isocyanate-terminated prepolymer; then adding a bionic structure lignin / molybdenum disulfide composite filler, and finally performing vacuum degassing to obtain a high-performance polyurethane adhesive.

[0015] The third object of the present invention is to provide the use of the high-performance polyurethane adhesive constructed with the above-mentioned bionic structure composite filler in bonding wood-based panels.

[0016] As an option, the wood-based panel is a poplar veneer, and the bonding is done in an overlapping manner with a glue coating amount of 200 g / m 2 .

[0017] Beneficial effects: (1) The present invention uses biomimetic structure lignin / molybdenum disulfide composite filler to undergo covalent / non-covalent cross-linking with castor oil and isocyanate, so that the polyurethane adhesive has better water-resistant bonding strength.

[0018] (2) The tannic acid in the present invention decomposes at high temperature to generate a phenolic carbon layer, which synergistically forms a dense carbonization barrier with the carbon source of lignin, thereby improving the flame retardant properties of the polyurethane adhesive.

[0019] (3) The narrow bandgap semiconductor properties of molybdenum disulfide in the present invention enable it to have strong absorption in the near-infrared region. After light energy is converted into heat energy, it is quickly conducted through the polyurethane matrix. In addition, the composite filler after ball milling forms a uniformly dispersed nanoscale heterojunction, which enhances the light absorption efficiency through the surface plasmon resonance effect, and significantly improves the light-to-heat conversion performance of the polyurethane adhesive.

[0020] (4) The ball milling exfoliation-ultrasonic self-assembly combined process of the present invention can achieve filler nano-sizing and uniform dispersion, avoid agglomeration problems, and break through the single performance limitation of traditional fillers, making it suitable for industrial production; sodium lignin sulfonate is a by-product of the papermaking industry and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a transmission electron microscopy image of the bionic structure lignin / molybdenum disulfide composite filler prepared in the present invention;

[0022] Figure 2 This is a graph showing the dry bonding strength of the high-performance polyurethane adhesive prepared by the present invention;

[0023] Figure 3This is a diagram of the wet bonding strength of the high-performance polyurethane adhesive prepared by the present invention;

[0024] Figure 4 This is a graph showing the peak heat release rate of the high-performance polyurethane adhesive prepared in the present invention;

[0025] Figure 5 This is a graph showing the total heat release of the high-performance polyurethane adhesive prepared in the present invention;

[0026] Figure 6 This is a diagram of the photothermal performance of the high-performance polyurethane adhesive prepared in the present invention. DETAILED DESCRIPTION

[0027] The specific implementation cases of the present invention can help those skilled in the art intuitively understand the additional advantages and technical effects of the invention. This technical solution allows different implementation methods to be adopted according to actual needs, and the technical details in the specification can also be adaptively modified based on different application scenarios, but they do not deviate from the core protection scope of the present invention. It should be noted that when the technical logic is reasonable, the various embodiments and their technical features can be freely combined for use.

[0028] Unless otherwise specified, the raw materials used in the examples of this specification are all conventional commercial products.

[0029] The preparation method of the biomimetic structure lignin / molybdenum disulfide composite filler used in the following examples is:

[0030] (1) Tannic acid, sodium lignin sulfonate, and molybdenum disulfide were accurately weighed and mixed at a mass ratio of 5:1:5. Deionized water was added to a solid content of 15-20 wt% to form a uniform suspension to ensure adequate contact between the components during ball milling. The reaction components were ball milled at 500 rpm for 36 hours using a planetary ball mill equipped with a zirconia milling jar and zirconia grinding balls (4 mm diameter).

[0031] (2) The milled slurry was transferred to a beaker, 200 mL of deionized water was added, and magnetic stirring was performed for 30 minutes. Then, probe ultrasonic treatment (power of 300 W) was performed for 1 hour to further peel off the remaining few layers of molybdenum disulfide. At the same time, the directional adsorption of tannic acid and lignin drove the nanosheets to stack in an orderly manner, forming biomimetic layered nanosheets. The post-ultrasonication dispersion was then centrifuged to collect the precipitate, washed with deionized water 3 times, and freeze-dried to obtain a biomimetic structure lignin / molybdenum disulfide composite filler. The transmission electron microscopy results are as follows: Figure 1 shown.

[0032] The specific embodiments are as follows:

[0033] Example 1

[0034] This embodiment provides a method for preparing a high-performance polyurethane adhesive constructed of a biomimetic structure composite filler with excellent bonding performance, flame retardancy, and light-to-heat conversion performance. The specific steps are as follows:

[0035] 100 parts by mass of castor oil were placed in a three-necked flask and vacuum-dehydrated at 80°C for 2 hours to remove moisture. The dehydrated castor oil was cooled to 60°C, and 50 parts of polydiphenylmethane diisocyanate (purchased from Wanhua Chemical Group Co., Ltd.) were slowly added to the mixture in proportion. Mechanical stirring was performed to mix thoroughly, with the addition amount calculated based on a molar ratio of isocyanate to hydroxyl group of 1.5:1. 0.05 parts of dibutyltin dilaurate as a catalyst were then added, and the mixture was stirred at room temperature for 1 hour. Seven parts of a biomimetic lignin / molybdenum disulfide composite filler were slowly added to the prepared polyurethane. The mixture was mechanically stirred at 600 rpm for 1 hour to ensure uniform distribution of the filler. Vacuum degassing was then performed for half an hour to remove air bubbles, resulting in a polyurethane adhesive with excellent bonding, flame retardancy, and photothermal conversion properties.

[0036] Example 2

[0037] Same as Example 1, except that the amount of biomimetic structure lignin / molybdenum disulfide composite filler in this example is 11 parts. The specific steps are as follows:

[0038] 100 parts of castor oil were placed in a three-necked flask and vacuum-dehydrated at 80°C for 2 hours to remove moisture. The dehydrated castor oil was cooled to 60°C and 50 parts of polydiphenylmethane diisocyanate (PDMI) were slowly added to the mixture in proportion. Mechanical stirring was performed to mix thoroughly, with the amount calculated based on a molar ratio of isocyanate to hydroxyl group of 1.5:1. 0.05 parts of dibutyltin dilaurate (DIBDI) catalyst were then added, and the mixture was stirred at room temperature for 1 hour. 11 parts of a biomimetic lignin / molybdenum disulfide composite filler were slowly added to the prepared polyurethane. Mechanical stirring was performed at 600 rpm for 1 hour to ensure uniform distribution of the filler. Vacuum degassing was then performed for half an hour to remove air bubbles, resulting in a polyurethane adhesive with excellent bonding, flame retardancy, and photothermal conversion properties.

[0039] Example 3

[0040] Same as Example 1, except that the amount of biomimetic structure lignin / molybdenum disulfide composite filler in this example is 15 parts. The specific steps are as follows:

[0041] 100 parts of castor oil were placed in a three-necked flask and vacuum-dehydrated at 80°C for 2 hours to remove moisture. The dehydrated castor oil was cooled to 60°C and 50 parts of polydiphenylmethane diisocyanate (PDMI) were slowly added to the mixture in proportion. Mechanical stirring was performed to mix thoroughly, with the amount calculated based on a molar ratio of isocyanate to hydroxyl group of 1.5:1. 0.05 parts of dibutyltin dilaurate (DIBDI) catalyst were then added and stirred at room temperature for 1 hour. 15 parts of a biomimetic lignin / molybdenum disulfide composite filler were slowly added to the prepared polyurethane. Mechanical stirring was performed at 600 rpm for 1 hour to ensure uniform distribution of the filler. Vacuum degassing was then performed for half an hour to remove air bubbles, resulting in a polyurethane adhesive with excellent bonding, flame retardancy, and photothermal conversion properties.

[0042] Example 4

[0043] Same as Example 1, except that the biomimetic structure lignin / molybdenum disulfide composite filler in this example is 20 parts. The specific steps are as follows:

[0044] 100 parts of castor oil were placed in a three-necked flask and vacuum-dehydrated at 80°C for 2 hours to remove moisture. The dehydrated castor oil was cooled to 60°C and 50 parts of polydiphenylmethane diisocyanate (PDMI) were slowly added to the mixture in proportion. Mechanical stirring was performed to mix thoroughly, with the amount calculated based on a molar ratio of isocyanate to hydroxyl group of 1.5:1. 0.05 parts of dibutyltin dilaurate (DIBDI) catalyst was then added, and the mixture was stirred at room temperature for 1 hour. 20 parts of a biomimetic lignin / molybdenum disulfide composite filler were slowly added to the prepared polyurethane. Mechanical stirring was performed at 600 rpm for 1 hour to ensure uniform distribution of the filler. Vacuum degassing was then performed for half an hour to remove air bubbles, resulting in a polyurethane adhesive with excellent bonding, flame retardancy, and photothermal conversion properties.

[0045] Comparative Example 1

[0046] The same as Example 3, except that no biomimetic structure lignin / molybdenum disulfide composite filler was added in this comparative example. The specific steps are as follows:

[0047] Place 100 parts of castor oil in a three-necked flask and vacuum dehydrate at 80°C for 2 hours to remove moisture. Cool the dehydrated castor oil to 60°C and slowly add 50 parts of polydiphenylmethane diisocyanate (PDMI) in appropriate proportions. Mechanically stir and mix thoroughly. Calculate the amount of polydiphenylmethane diisocyanate to achieve a molar ratio of isocyanate to hydroxyl of 1.5:1. Then, add 0.05 parts of dibutyltin dilaurate as a catalyst and stir at room temperature for 1 hour.

[0048] Comparative Example 2

[0049] The method is the same as Example 3, except that, in this comparative example, the method combining ball milling exfoliation and ultrasonic self-assembly is replaced by ultrasonic treatment alone to prepare the lignin / molybdenum disulfide composite filler.

[0050] The preparation method of the lignin / molybdenum disulfide composite filler is the same as the preparation method of the biomimetic structure lignin / molybdenum disulfide composite filler, except that the ball milling process is not used.

[0051] The preparation method of the high-performance polyurethane adhesive constructed from the lignin / molybdenum disulfide composite filler in this comparative example comprises the following specific steps:

[0052] 100 parts of castor oil were placed in a three-necked flask and vacuum-dehydrated at 80°C for 2 hours to remove moisture. The dehydrated castor oil was cooled to 60°C and 50 parts of polydiphenylmethane diisocyanate (PDMC) were slowly added to the mixture in proportion. Mechanical stirring was performed to achieve a molar ratio of isocyanate to hydroxyl groups of 1.5:1. 0.05 parts of dibutyltin dilaurate (DBT) catalyst was then added and the mixture was stirred at room temperature for 1 hour. 15 parts of the lignin / molybdenum disulfide composite filler, prepared by ultrasonic treatment alone, were slowly added to the polyurethane prepared above. Mechanical stirring was performed at 600 rpm for 1 hour to ensure uniform distribution of the filler. Vacuum degassing was then performed for half an hour to remove air bubbles, resulting in a polyurethane adhesive reinforced with the lignin / molybdenum disulfide composite filler.

[0053] Comparative Example 3

[0054] The same as Example 3, except that the biomimetic structure lignin / molybdenum disulfide composite filler is replaced with molybdenum disulfide in this comparative example. The specific steps are as follows:

[0055] Place 100 parts of castor oil in a three-necked flask and vacuum dehydrate at 80°C for 2 hours to remove moisture. Cool the dehydrated castor oil to 60°C and slowly add 50 parts of polydiphenylmethane diisocyanate (PDMI) in proportion to the mixture. Mechanically stir and mix thoroughly, calculating the amount based on a molar ratio of isocyanate to hydroxyl of 1.5:1. Then, add 0.05 parts of the catalyst dibutyltin dilaurate and stir at room temperature for half an hour. Slowly add 15 parts of molybdenum disulfide to the polyurethane prepared above and mechanically stir at 600 rpm for 1 hour to ensure uniform distribution of the filler. Then, vacuum degassing is performed for half an hour to remove bubbles, resulting in a polyurethane adhesive reinforced with molybdenum disulfide.

[0056] Comparative Example 4

[0057] This is the same as Example 3, except that the biomimetic structure lignin / molybdenum disulfide composite filler is replaced with a molybdenum disulfide / lignin co-milled composite filler to which tannic acid is not added. The preparation method of the molybdenum disulfide / lignin co-milled composite filler to which tannic acid is not added is the same as the preparation method of the biomimetic structure lignin / molybdenum disulfide composite filler, except that tannic acid is not added.

[0058] This comparative example provides a method for preparing a high-performance polyurethane adhesive constructed with a biomimetic structure composite filler, and the specific steps are as follows:

[0059] 100 parts of castor oil were placed in a three-necked flask and vacuum-dehydrated at 80°C for 2 hours to remove moisture. The dehydrated castor oil was cooled to 60°C, and 50 parts of polydiphenylmethane diisocyanate (PDMI) were slowly added to the mixture in proportion. Mechanical stirring was performed to achieve a molar ratio of isocyanate to hydroxyl group of 1.5:1. 0.05 parts of dibutyltin dilaurate (DBT) catalyst were then added, and the mixture was stirred at room temperature for 1 hour. 15 parts of the co-milled molybdenum disulfide / lignin composite filler, which had not been added with tannic acid, were slowly added to the prepared polyurethane. Mechanical stirring was performed at 600 rpm for 1 hour to ensure uniform distribution of the filler. Vacuum degassing was then performed for half an hour to remove air bubbles, resulting in a polyurethane adhesive reinforced with the MOS / lignin composite filler.

[0060] Test example

[0061] The high performance polyurethane adhesives prepared in Examples 1-4 and Comparative Examples 1-4 were mixed at 200 g / m 2 The glue is applied to the poplar veneer and bonded by overlapping, with a gluing area of ​​625 mm 2 The veneers were glued and cured at 123°C for 20 minutes. The bonding strength was tested using a universal mechanical testing machine. The results of dry and wet bonding strength are shown below. Figure 2 and Figure 3 .

[0062] Through Figure 2 and Figure 3A comparative analysis shows that compared with Comparative Example 1, the dry bonding strength and wet bonding strength of Comparative Examples 2, 3 and 4 all show a slight increase. Due to the inherent characteristics of castor oil, the cohesive strength of the adhesive is insufficient, resulting in poor bonding performance. The introduction of molybdenum disulfide can preliminarily improve the bonding performance of the adhesive through its lamellar structure reinforcement effect. When it forms a composite system with lignin, molybdenum disulfide and lignin form a synergistic reinforcement network, further improving the dry / wet bonding strength. However, in-depth research found that the agglomeration tendency of the molybdenum disulfide-lignin system significantly reduces the dispersion effect, and the lack of surface reactive functional groups and insufficient compatibility with the polyurethane matrix seriously restrict its reinforcement efficiency. Therefore, in the examples, a multi-layered reinforcement system was constructed using a combined ball milling exfoliation and ultrasonic self-assembly method. Tannic acid, molybdenum disulfide, and lignin were compositely assembled to create a reinforcing phase with a biomimetic layered structure. This not only promotes nano-dispersion of molybdenum disulfide / lignin, but also introduces reactive groups such as hydroxyl groups on their surfaces, enhancing chemical bonding with the polyurethane matrix. Experimental data showed that, with the same amount of composite filler, Example 3 achieved 33.3% and 35.6% higher dry and wet bond strengths than Comparative Example 4, respectively, fully demonstrating the effectiveness of this modification strategy. When the biomimetic lignin / molybdenum disulfide composite filler addition level is within a certain range (Examples 1-3), the dry and wet bond strengths of the adhesive show a significant positive correlation with the filler content. This is primarily due to the fact that an appropriate amount of filler effectively enhances the strength of the polyurethane matrix through stress transfer and crack deflection. However, excessive filler addition can cause stress concentration due to agglomeration, reducing the strength of the polyurethane adhesive (Example 4). In addition, under the same addition amount, the dry / wet bonding strength of Comparative Example 2 is significantly lower than that of Example 3, indicating that the lignin / molybdenum disulfide composite filler prepared by the synergistic effect of ball milling exfoliation and ultrasonic self-assembly technology can more effectively improve the interfacial bonding performance of the polyurethane adhesive compared with the single ultrasonic exfoliation process.

[0063] The flame retardant properties of the polyurethane adhesives prepared in Comparative Examples 1, 3 and 4 and Example 3 were analyzed. The results are as follows: Figure 4 and Figure 5As shown in Figure 2, the peak heat release rate and total heat release of Comparative Example 1 were 241.3 W / g and 35.1 KJ / g, respectively. The introduction of molybdenum disulfide (Comparative Example 3) or molybdenum disulfide / lignin co-ball-milled composite filler (Comparative Example 4) resulted in a decrease in both the peak heat release rate and total heat release of the castor oil polyurethane adhesive. Because molybdenum disulfide has a lamellar structure similar to graphene, it can form a dense physical barrier in the adhesive matrix, effectively blocking the transfer path of oxygen and heat. At the same time, lignin can pyrolyze at high temperatures to form a porous carbon layer, preventing heat and combustible gases from penetrating into the adhesive. Compared with Comparative Example 4, the peak heat release rate of Example 3 decreased from 235.6 W / g to 222.4 W / g, and the total heat release was further reduced, confirming that the introduction of tannic acid during the ball milling process made molybdenum disulfide and lignin more evenly dispersed and formed a bionic composite structure, increasing the contact area between the filler and the polyurethane matrix, which was beneficial to increasing the tortuosity of the heat transfer path, delaying heat conduction, and improving the flame retardant properties of the polyurethane adhesive.

[0064] The light and heat performance of the polyurethane adhesive prepared in Example 3 and Comparative Example 1 were analyzed. Figure 6 As shown. Under simulated natural light conditions, the temperature of Comparative Example 1 increased from 35.8°C to 55.7°C after 120 seconds of illumination. This is mainly due to the π-π electron transitions of the carbamate groups on the polyurethane backbone, which can absorb ultraviolet-visible light and convert light energy into heat energy. At the same time, the ricinoleic acid in castor oil has a conjugated olefin structure, which absorbs near-infrared light and enhances its wide-spectrum response. The polyurethane adhesive prepared in Example 3 increased from an initial temperature of 38.9°C to 90.4°C after 120 seconds of illumination. A longer illumination time (300 seconds) increased the temperature of the adhesive surface to 96.0°C, an increase of nearly 40°C compared to Comparative Example 1 (59.8°C). This shows that the polyurethane adhesive reinforced with the biomimetic lignin / molybdenum disulfide composite filler has excellent light-to-heat conversion efficiency. This is mainly due to the introduction of photothermally active fillers (molybdenum disulfide and lignin), which enhances the absorption path of light energy and improves light energy utilization.

[0065] While this specification has detailed the core principles, embodiments, and verification data of the invention, those skilled in the art may, based on the technical insights of this invention, make adaptive adjustments or optimizations to its implementation. Therefore, equivalent replacements or partial improvements based on the innovative essence of this invention fall within the scope of protection defined by the claims.

Claims

1. A high-performance polyurethane adhesive constructed with a biomimetic structural composite filler, characterized in that: The raw materials of the high-performance polyurethane adhesive are proportioned as follows by mass: 50 parts of polydiphenylmethane diisocyanate, 100 parts of castor oil, 7-20 parts of biomimetic structure lignin / molybdenum disulfide composite filler, and 0.05-0.1 parts of catalyst. The preparation method of the biomimetic structure lignin / molybdenum disulfide composite filler is as follows: after fully mixing tannic acid, lignin and molybdenum disulfide, deionized water is added to ensure sufficient contact of the reaction components during the ball milling process, after ball milling using a planetary ball mill, the mixture is washed with deionized water and subjected to ultrasound to achieve self-assembly of lignin / molybdenum disulfide composite filler nanosheets, and finally the biomimetic structure lignin / molybdenum disulfide composite filler is prepared by centrifugation and freeze-drying.

2. The high-performance polyurethane adhesive constructed with a biomimetic structural composite filler according to claim 1, characterized in that: The average functionality of the castor oil is 2.7, and the ricinoleic acid content is greater than 80%.

3. The high-performance polyurethane adhesive constructed with a biomimetic structural composite filler according to claim 1, characterized in that: The catalyst is dibutyltin dilaurate.

4. The high-performance polyurethane adhesive constructed with a biomimetic structural composite filler according to claim 1, characterized in that: The lignin is lignin sulfonate.

5. The high-performance polyurethane adhesive constructed with a biomimetic structural composite filler according to claim 1, characterized in that: The mass ratio of the tannic acid, lignin and molybdenum disulfide is 5:1:

5.

6. The high-performance polyurethane adhesive constructed with a biomimetic structural composite filler according to claim 1, characterized in that: The ball milling speed is 500 rpm and the time is 36 hours.

7. The high-performance polyurethane adhesive constructed with a biomimetic structural composite filler according to claim 1, characterized in that: Deionized water was added to a solid content of 15-20 wt% to ensure sufficient contact of the reaction components during ball milling.

8. A method for preparing a high-performance polyurethane adhesive based on the biomimetic structure composite filler according to claim 1, characterized in that: The steps are as follows: vacuum-dehydrated castor oil and polydiphenylmethane diisocyanate are added to a reaction vessel, stirred evenly, then a catalyst is added, and the stirring reaction is continued to obtain an isocyanate-terminated prepolymer; then a biomimetic structure lignin / molybdenum disulfide composite filler is added, and finally vacuum degassing is performed to obtain a high-performance polyurethane adhesive.

9. Use of the high-performance polyurethane adhesive constructed with the biomimetic structural composite filler according to claim 1 in bonding wood-based panels.

10. The use according to claim 9, characterized in that The wood-based panels are poplar veneers, which are bonded in an overlapping manner with a glue coating of 200 g / m 2 .

Images