A thermally conductive plant protein-based adhesive and its preparation method and application

Abstract

The present invention provides a heat-conductive plant protein-based composition and a heat-conductive plant protein adhesive, as well as a preparation method and application thereof. The heat-conductive plant protein-based composition provided by the present invention is obtained by ball milling raw materials including a heat-conductive filler, a modified plant protein and (3-(methacrylamido)propyl)trimethylammonium chloride in a mass ratio of 1: (0.3-5): (0.03-1) for 15-25 hours. The heat-conductive plant protein adhesive of the present invention, its raw materials include 6-20wt% of the heat-conductive plant protein-based composition and 3-8wt% of a cross-linking agent, and on this basis, it can further include 0.1-3wt% of a flame retardant enhancer. The heat-conductive plant protein adhesive provided by the present invention, using the heat-conductive plant protein-based composition, has good bonding performance and water resistance, as well as good thermal conductivity, flame retardancy and mildew resistance, is conducive to the preparation of multifunctional materials, and is conducive to industrial applications, especially in the field of artificial board industry.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass adhesives. Specifically, the present invention provides a thermally conductive plant protein-based composition and a preparation method thereof, and also provides a thermally conductive plant protein adhesive and a preparation method and application thereof. Background Art

[0002] Valuable timber resources are relatively scarce, while planted forests are abundant. Therefore, the use of fast-growing plantation wood combined with adhesives to produce wood-based panels has become a primary choice for furniture, flooring, and interior decoration. Wood-based panels are produced in large quantities and are mostly plywood products, with aldehyde resins and their modified products as the primary adhesives.

[0003] In recent years, soy protein adhesives have garnered widespread attention as potential substitutes for formaldehyde-based resins. Research on soy protein adhesives in the production of wood-based panels continues to deepen, potentially helping to reduce formaldehyde pollution in human settlements and promote sustainable development. With improved living standards, demand for wood-based composite materials with multifunctional properties, such as flame retardancy, mildew resistance, and thermal conductivity, is increasing. In adhesives and their composites, thermal conductivity plays a key role not only in thermal management but also in the development of geothermal flooring and energy-storage biocomposites. However, achieving flame retardancy, mildew resistance, and thermal conductivity while enhancing the water resistance of soy protein adhesives remains a challenge, requiring overcoming technical difficulties and further research and exploration.

[0004] The Chinese patent with the announcement number CN103387812B discloses a water-resistant soybean-based adhesive. The soybean protein molecules in the defatted soybean meal powder are first modified with an alkaline solution (sodium hydroxide or sodium lauryl sulfate), which can fully disperse and expand the soybean protein, exposing more polar and non-polar groups, laying the foundation for the cross-linking reaction of the soybean protein; then an acid solution is added to modify the soybean protein molecules again, and the pH is adjusted to 3-4. Under this pH condition, the interaction force between the soybean proteins is increased, and its water resistance is improved. At the same time, it has the advantages of Finally, the addition of a modifier further modifies the soy protein, increasing the number of reactive groups in the reaction system. A large number of amino and hydroxyl groups on the soy protein react with the modifier under acidic conditions to form crosslinks, reducing the number of hydrophilic groups and improving water resistance. Furthermore, the modifier will self-polymerize in the reaction system, forming a denser network structure with a higher degree of crosslinking than ordinary untreated protein adhesives after curing. This strengthens the cohesion of the adhesive layer and makes it difficult for moisture to enter the internal adhesive layer, thereby improving the water resistance and bonding strength of the entire reaction system. The addition of an appropriate proportion of modifier can effectively enhance the initial adhesion of the soy protein adhesive, improve the interfacial compatibility between the adhesive and the board, and enhance the bonding effect.

[0005] The water-resistant soy protein-based adhesives provided in the above prior art have problems of insufficient thermal conductivity and high heat transfer inertia during application, which may lead to poor performance in the field of heat conduction (such as thermal conductive flooring) and fail to meet the requirements of use. Summary of the Invention

[0006] The first purpose of the present invention is to improve the thermal conductivity of the plant protein adhesive in the prior art and provide a thermally conductive plant protein-based composition, which is obtained by ball milling raw materials including a thermally conductive filler, a modified plant protein and (3-(methacrylamido)propyl)trimethylammonium chloride in a mass ratio of 1: (0.3-5): (0.03-1) for 15-25 hours.

[0007] In some embodiments of the present invention, the mass ratio of the thermal conductive filler, the modified plant protein and (3-(methacrylamido)propyl)trimethylammonium chloride is 1:(1-3):(0.2-0.6).

[0008] The ball milling method is used, and the above raw materials and their proportions are combined to obtain a thermally conductive plant protein-based composition for the preparation of an adhesive. The resulting thermally conductive adhesive has good thermal conductivity, flame retardancy and antibacterial properties while ensuring water resistance.

[0009] In some embodiments of the present invention, the modified plant protein is modified with a modifying agent.

[0010] In some embodiments of the present invention, the modified plant protein is prepared from a raw material comprising plant protein and a modifier in a mass ratio of (15-18): (0.9-1.2); preferably, the mass ratio of the plant protein to the modifier is 15: (0.9-1.2).

[0011] In some embodiments of the present invention, the preparation of the modified plant protein is carried out in the presence of a solvent (such as water); the reaction temperature is 25-30°C, the reaction time is 1-3 hours, and it is carried out under stirring conditions, for example, the stirring rate is 200-300 rmp, and the freeze-drying time is 5-10 hours.

[0012] In some embodiments of the present invention, the plant protein is selected from at least one of soy protein, corn protein, peanut protein, pea protein and rice protein.

[0013] In some embodiments of the present invention, the modifier is selected from at least one of sodium lauryl sulfate, urea and guanidine hydrochloride.

[0014] In the preparation method of the thermally conductive plant protein-based composition provided by the present invention, the modified plant protein is prepared from a modifier (such as sodium lauryl sulfate) and plant protein. Modification of the plant protein by the modifier (such as sodium lauryl sulfate) effectively promotes the exposure of active functional groups in the plant protein. This modification strategy significantly enhances the mechanical and electrostatic bonding ability of the plant protein with thermally conductive fillers (such as graphene) and (3-(methacrylamido)propyl)trimethylammonium chloride during the subsequent mechanical ball milling process. The thermally conductive plant protein-based composition prepared by the present invention can thus better form a complete and continuous thermal conductive pathway in the thermally conductive adhesive system, thereby significantly optimizing heat transfer performance.

[0015] In some embodiments of the present invention, the protein content of the plant protein is 80%-90%. Thus, the thermally conductive plant protein-based composition can better improve the thermal conductivity of the adhesive.

[0016] In some embodiments of the present invention, the thermally conductive filler is selected from at least one of graphene, boron nitride, and carbon nanotubes. By using these specific types of thermally conductive fillers, particularly graphene, the thermally conductive plant protein-based composition can further improve the thermal conductivity of the adhesive.

[0017] In some embodiments of the present invention, the particle size of the thermally conductive filler is 3-5 μm. Thus, the thermally conductive plant protein-based composition can better improve the thermal conductivity of the adhesive.

[0018] A second object of the present invention is to provide a method for preparing the aforementioned thermally conductive plant protein-based composition, wherein the ball milling speed is 500-800 rpm, thereby improving efficiency and achieving efficient preparation of the thermally conductive plant protein-based composition.

[0019] The preparation method of the thermally conductive plant protein-based composition provided by the present invention adopts ball milling treatment. The thermally conductive filler (such as graphene) and (3-(methacrylamido)propyl)trimethylammonium chloride can be efficiently combined with the modified plant protein through mechanical ball milling, thereby achieving good compatibility with the plant protein. Not only does it play a physical filling role in the adhesive system, but due to the good thermal conductivity of the thermally conductive filler (such as graphene), a stable and continuous thermal conductive pathway can be formed in the wood composite material prepared with the plant protein adhesive, thereby giving the plant protein adhesive thermal conductivity and facilitating the preparation of the thermally conductive composite material. The natural antibacterial property of (3-(methacrylamido)propyl)trimethylammonium chloride gives the plant protein adhesive mildew resistance, and its presence is conducive to improving the interfacial interaction between the thermally conductive filler (such as graphene) and the plant protein, promoting the formation of a thermal conductive pathway in the adhesive system, thereby improving the thermal conductivity of the thermally conductive plant protein adhesive. In particular, the ball milling conditions within the above range can significantly improve the thermal conductivity effect. In particular, the ball milling time within the above range can ensure the successful preparation of the composition and improve the thermal conductivity.

[0020] The third object of the present invention is to provide an application of the aforementioned thermally conductive plant protein-based composition in an adhesive. Specifically, a thermally conductive plant protein adhesive is provided, the raw materials of which include 6-20wt% of the aforementioned thermally conductive plant protein-based composition and 3-8wt% of a cross-linking agent.

[0021] Preferably, based on the total mass of the thermally conductive plant protein adhesive, the content of the thermally conductive plant protein-based composition is 12-16%, for example, 12%, 13%, 14%, 15% or 16%. If the content of the thermally conductive plant protein-based composition is lower than 12%, it will not achieve the ideal effect of improving thermal conductivity.

[0022] Preferably, based on the total mass of the thermally conductive plant protein adhesive, the content of the cross-linking agent is 3-6%, for example, 3%, 4%, 5% or 6%. If the content of the cross-linking agent is lower than 3%, a tight cross-linking structure cannot be formed in the adhesive system, resulting in poor water resistance of the adhesive; if the content is too high, for example, more than 6%, the viscosity of the adhesive decreases, affecting the gluing.

[0023] In some embodiments of the present invention, the cross-linking agent is prepared by nucleophilic reaction of hexachlorocyclotriphosphazene and p-dimethylaminobenzaldehyde in a mass ratio of 1:(2-5), for example, the mass ratio of hexachlorocyclotriphosphazene and p-dimethylaminobenzaldehyde is 1:2, 1:3, 1:4 or 1:5.

[0024] In some embodiments of the present invention, the nucleophilic reaction is carried out in the presence of an anhydrous solvent; and / or, the nucleophilic reaction is carried out at a temperature of 30-50° C. and a stirring rate of 300-600 rpm for 3-6 hours.

[0025] The heat-conductive plant protein adhesive provided by the present invention adopts the cross-linking agent prepared from p-dimethylaminobenzaldehyde and hexachlorocyclotriphosphazene, which can significantly enhance the bonding performance of the plant protein adhesive.

[0026] In some embodiments of the present invention, the raw materials for preparing the thermally conductive plant protein adhesive further include 0.1-3 wt% of a flame retardant reinforcing agent, preferably 1-2 wt% of a flame retardant reinforcing agent.

[0027] The thermally conductive plant protein adhesive provided by the present invention utilizes a simple Schiff base reaction to efficiently crosslink a crosslinker with a flame retardant enhancer and the protein adhesive system. The hyperbranched aldehyde groups contained in the crosslinker are evenly distributed throughout the protein adhesive system, forming chemical bonds, thereby building a stable crosslinked network structure and improving the adhesive's bonding performance and water resistance. In particular, the ratio of the flame retardant enhancer to the crosslinker is within the range of (0.1-3):(3-8), particularly (1-2):(3-6), achieving a synergistic effect in improving the bonding strength of the thermally conductive plant protein adhesive.

[0028] In some embodiments of the present invention, the mass ratio of the thermally conductive plant protein-based composition, the flame retardant reinforcing agent and the cross-linking agent is 13:1:3, 14:1:3, 15:1:3, 13:1:4, 14:1:4 or 15:1:4.

[0029] In some embodiments of the present invention, the flame retardant reinforcing agent is obtained by cross-linking reaction of succinic anhydride, diethylenetriamine and hexachlorocyclotriphosphazene, and the cross-linking reaction includes a first stage reaction, a second stage reaction and a third stage reaction.

[0030] In some embodiments of the present invention, the first stage reaction is: succinic anhydride and diethylenetriamine in a mass ratio of (0.5-3): (0.5-2) are reacted at a temperature of 30-50° C. and a stirring rate of 200-400 rpm for 3-5 hours.

[0031] In some embodiments of the present invention, the mass ratio of succinic anhydride to diethylenetriamine is 1:(0.5-1).

[0032] In some embodiments of the present invention, the second stage reaction is: continuing the reaction at a temperature of 120-150° C. for 3-6 hours to obtain a reaction product H.

[0033] In some embodiments of the present invention, the third stage reaction is: the reaction product H and hexachlorocyclotriphosphazene in a mass ratio of 1: (0.1-0.3) are reacted at a temperature of 60-90°C and a stirring rate of 200-400 rpm for 13-16 hours; the flame retardant enhancer is obtained.

[0034] The thermally conductive plant protein adhesive provided by the present invention uses the flame retardant enhancer prepared by reacting hexachlorocyclotriphosphazene, succinic anhydride and diethylenetriamine, which can significantly improve the flame retardancy of the plant protein adhesive system, cooperate with the cross-linking agent to promote the construction of the cross-linking structure in the adhesive system, and improve the bonding strength of the adhesive.

[0035] In some embodiments of the present invention, the raw materials of the thermally conductive plant protein adhesive are: 6-20 wt% of the thermally conductive plant protein-based composition, 0.3-3 wt% of the flame retardant enhancer, 3-8 wt% of the cross-linking agent and the balance dispersion medium.

[0036] In some embodiments of the present invention, the raw materials of the thermally conductive plant protein adhesive are: 12-16 wt% of the thermally conductive plant protein-based composition, 1-2 wt% of the flame retardant enhancer, 3-6 wt% of the cross-linking agent and the balance dispersion medium.

[0037] A fourth object of the present invention is to provide a method for preparing the aforementioned thermally conductive plant protein adhesive, comprising the following steps:

[0038] (1) uniformly mixing the heat-conductive plant protein-based composition with a dispersion medium;

[0039] (2) Add the cross-linking agent and mix evenly to obtain the thermal conductive plant protein adhesive.

[0040] In some embodiments of the present invention, in step (2), the flame retardant reinforcing agent is first added and mixed evenly; and then the cross-linking agent is added.

[0041] In some embodiments of the present invention, the dispersion medium is water.

[0042] In some embodiments of the present invention, the water is selected from at least one of tap water, softened water, and distilled water.

[0043] The fifth object of the present invention is to provide an application of the aforementioned thermally conductive plant protein adhesive in the fields of artificial board industry, thermal management and energy storage materials.

[0044] In some embodiments of the present invention, a wood-based panel is provided, wherein the wood-based panel uses the aforementioned thermally conductive plant protein adhesive, for example, a three-layer plywood bonded using the aforementioned thermally conductive plant protein adhesive.

[0045] The present invention has the following beneficial effects:

[0046] (1) The thermally conductive plant protein adhesive provided by the present invention not only meets the requirements of bonding strength and water resistance, but also has thermal conductivity, flame retardancy and mildew resistance, which is conducive to the preparation of multifunctional materials;

[0047] (2) The thermally conductive plant protein adhesive provided by the present invention is beneficial for achieving stress balance in the preparation of plywood and improving its bonding performance;

[0048] (3) The thermally conductive plant protein-based composition provided by the present invention is conducive to ensuring the uniform dispersion effect of the plant protein adhesive system;

[0049] (4) The thermally conductive plant protein adhesive provided by the present invention does not add toxic substances, and the components are matched in reasonable amounts. The synthetic adhesive has high efficiency, no harmful substance release, high product reactivity, good processability, stable performance in each batch, low cost, and is conducive to industrial application.

[0050] Experiments have demonstrated that the thermally conductive plant protein adhesive provided by the present invention easily forms a cross-linked structure, has a high cross-linking density, and is simple to synthesize. It exhibits excellent thermal conductivity, flame retardancy, and mildew resistance. The resulting plywood exhibits stable performance, significantly reduced interfacial weakness, good dry strength, excellent water-resistant bonding, and consistent product quality. The thermally conductive plant protein adhesive provided by the present invention meets the requirements for water resistance and versatility in plywood adhesives, ensuring the practical performance of biomass adhesives and their use in preparing wood-based composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0052] Figure 1 This is one of the thermal conductivity comparison diagrams of the thermally conductive plant protein adhesive provided by the present invention applied to artificial boards. DETAILED DESCRIPTION

[0053] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0054] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents, etc. used in the following examples are all commercially available.

[0055] In the present invention, if the percentage sign "%" is involved, unless otherwise specified, it refers to mass percentage; however, the percentage of a solution, unless otherwise specified, refers to the number of grams of solute contained in 100 ml of the solution; the percentage between liquids refers to the volume ratio at 20°C.

[0056] The water used in the embodiments of the present invention is tap water.

[0057] The plant protein used in the embodiment of the present invention is soy protein isolate, with a protein content of 90% and a particle size of 250 mesh.

[0058] The modifier used in the embodiment of the present invention is sodium lauryl sulfate, with a molecular weight of 288.4.

[0059] The thermal conductive filler used in the embodiment of the present invention is graphene, and the average particle size is 300 mesh.

[0060] The molecular weight of (3-(methacrylamido)propyl)trimethylammonium chloride used in the examples of the present invention is 206.7.

[0061] The molecular weight of the hexachlorocyclotriphosphazene used in the examples of the present invention is 348.

[0062] The molecular weight of succinic anhydride used in the examples of the present invention is 100.

[0063] The molecular weight of diethylenetriamine used in the examples of the present invention is 103.

[0064] The molecular weight of p-dimethylaminobenzaldehyde used in the examples of the present invention is 149.2.

[0065] The preparation method of the thermally conductive plant protein adhesive provided by the present invention comprises:

[0066] (1) 15-18 parts by weight of vegetable protein, 0.9-1.2 parts by weight of sodium lauryl sulfate, and 80-84 parts of water are placed in a beaker, stirred at a stirring rate of 200-300 rpm at a temperature of 25-30° C. for 1-3 hours until a uniform and stable state is obtained, and freeze-dried for 5-10 hours to obtain a modified vegetable protein;

[0067] (2) 6-8 parts by weight of graphene, 6-8 parts by weight of the modified plant protein, and 0.2-0.5 parts of (3-(methacrylamido)propyl)trimethylammonium chloride are placed in a ball mill, and mixed at a ball milling rate of 650-700 rpm (e.g., 22-24 hours) until uniform, to obtain a thermally conductive plant protein-based composition;

[0068] (3) adding 12-16 parts by weight of the thermally conductive plant protein-based composition to 75-85 parts by weight of water, and stirring (e.g., 15-20 minutes) until the solution is uniform and stable;

[0069] (4) Add 1-2 parts by weight of the flame retardant enhancer to the system and stir (e.g., for 10-15 minutes) until the solution is uniform and stable;

[0070] (5) Continue to add 3-6 parts by weight of a cross-linking agent to the system and stir evenly (for example, continue stirring for 10-20 minutes) to obtain the thermal conductive plant protein adhesive.

[0071] Preferably, the total weight parts of the above raw materials is 100 parts, that is, the amount of the above weight parts can also be directly expressed as mass percentage, and in the following examples, 1 part = 1g.

[0072] Example 1

[0073] This embodiment provides a thermally conductive plant protein-based composition, and the preparation method thereof is as follows:

[0074] (A) Preparation of modified plant protein: 15 g of plant protein, 80 g of water, and 1 g of sodium lauryl sulfate were placed in a beaker, stirred at 250 rpm and 25° C. for 2 h, and the resulting solution was freeze-dried for 6 h to obtain the modified plant protein;

[0075] (B) 1 g of the modified plant protein obtained in step (A), 1 g of graphene, and 0.2 g of (3-(methacrylamido)propyl)trimethylammonium chloride were placed in a beaker and mechanically ball-milled at a rate of 650 rpm and a temperature of 30° C. for 24 h to obtain the thermally conductive plant protein-based composition.

[0076] In this embodiment, the thermally conductive plant protein-based composition is applied to an adhesive to obtain a thermally conductive plant protein adhesive. The preparation method of the thermally conductive plant protein adhesive is as follows:

[0077] (1) Preparation of a cross-linking agent: 0.1 mol of hexachlorocyclotriphosphazene and 0.4 mol of p-dimethylaminobenzaldehyde were placed in a three-necked flask equipped with a stirrer, and the mixture was reacted for 3 h at a stirring rate of 400 rpm and a temperature of 30°C to obtain the cross-linking agent;

[0078] (2) Preparation of flame retardant reinforcing agent: 0.1 mol of succinic anhydride and 0.07 mol of diethylenetriamine were placed in a three-necked flask equipped with a stirrer for cross-linking reaction. The cross-linking reaction can be divided into three stages:

[0079] The first stage of reaction: the reaction was carried out at a stirring rate of 300 rpm and a temperature of 50°C for 3 h;

[0080] The second stage of reaction: the temperature was raised to 140 °C, the stirring rate was 400 rpm, and the reaction was continued for 3 h to obtain the reaction product H;

[0081] The third stage reaction: 0.2 mol of hexachlorocyclotriphosphazene and 1 mol of the reaction product H were placed in a three-necked flask equipped with a stirrer, and the reaction was carried out for 15 hours at a temperature of 70° C. and a stirring rate of 400 rpm to obtain the flame retardant enhancer;

[0082] (3) Add 79.5 g of water to the thermally conductive plant protein-based composition (15 g) prepared in this example and stir for 10 min until the solution becomes uniform and stable;

[0083] (4) Add 1.5 g of the flame retardant enhancer prepared in step (2) to the system and stir for 15 minutes until the solution is uniform and stable;

[0084] (5) Continue to add 4 g of the cross-linking agent prepared in step (1) into the system and continue stirring for 10 minutes to obtain the thermal conductive plant protein adhesive.

[0085] Example 2

[0086] This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that, in the preparation method of the thermally conductive plant protein adhesive, the amount of water added in step (3) is adjusted from 79.5 g to 80 g, and the amount of flame retardant enhancer added in step (4) is 1 g.

[0087] Example 3

[0088] This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that, in the preparation method of the thermally conductive plant protein adhesive, the amount of water added in step (3) is adjusted from 79.5 g to 75.5 g, and the amount of cross-linking agent added in step (5) is 8 g.

[0089] Example 4

[0090] This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that, in the preparation method of the thermally conductive plant protein adhesive, the amount of water added in step (3) is adjusted from 79.5 g to 81.5 g, and the amount of cross-linking agent added in step (5) is 2 g.

[0091] Example 5

[0092] This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that, in the preparation method of the thermally conductive plant protein-based composition, the mass ratio of the graphene, modified plant protein, and (3-(methacrylamido)propyl)trimethylammonium chloride is 1:2:0.2.

[0093] Example 6

[0094] This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that, in the preparation method of the thermally conductive plant protein-based composition, the mass ratio of the graphene, modified plant protein, and (3-(methacrylamido)propyl)trimethylammonium chloride is 1:4:0.2.

[0095] Example 7

[0096] This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that, in the preparation method of the thermally conductive plant protein-based composition, the mass ratio of the graphene, modified plant protein, and (3-(methacrylamido)propyl)trimethylammonium chloride is 1:1:0.1.

[0097] Example 8

[0098] This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that, in the preparation method of the cross-linking agent, the mass ratio of the hexachlorocyclotriphosphazene to p-dimethylaminobenzaldehyde is 1:2.

[0099] Example 9

[0100] This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that, in the preparation method of the cross-linking agent, the mass ratio of the hexachlorocyclotriphosphazene to p-dimethylaminobenzaldehyde is 1:5.

[0101] Comparative Example 1

[0102] This comparative example provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that the cross-linking agent is not added.

[0103] Comparative Example 2

[0104] This comparative example provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that the flame retardant enhancer is not added.

[0105] Comparative Example 3

[0106] This comparative example provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that in the preparation method of the thermally conductive plant protein-based composition, the plant protein is not modified with sodium lauryl sulfate.

[0107] Comparative Example 4

[0108] This comparative example provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, with the only difference being that in the preparation method of the thermally conductive plant protein-based composition, the mass ratio of the graphene, modified plant protein, and (3-(methacrylamido)propyl)trimethylammonium chloride is 0:1:0.1.

[0109] Comparative Example 5

[0110] This comparative example provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, with the only difference being that in the preparation method of the thermally conductive plant protein-based composition, the mass ratio of the graphene, modified plant protein, and (3-(methacrylamido)propyl)trimethylammonium chloride is 1:1:0.

[0111] Comparative Example 6

[0112] This comparative example provides an adhesive, which is a common E0 grade urea-formaldehyde resin adhesive (purchased from Shandong Qiansen Wood Industry Co., Ltd.).

[0113] Comparative Example 7

[0114] This comparative example provides a plant protein adhesive, and the preparation steps are as follows: 15g of soy protein is added to 85g of water and stirred for 20 minutes to obtain the plant protein adhesive.

[0115] Comparative Example 8

[0116] This comparative example provides a thermally conductive plant protein adhesive, and the preparation steps are as follows: 15g of soy protein is added to 81g of water, stirred for 20 minutes, and then 4g of a polyamide epichlorohydrin crosslinker is added to obtain a thermally conductive plant protein adhesive.

[0117] Comparative Example 9

[0118] This comparative example provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that in the preparation method of the flame retardant enhancer, diethylenetriamine is replaced by ethylenediamine.

[0119] Comparative Example 10

[0120] This comparative example provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that in the preparation method of the flame retardant enhancer, diethylenetriamine is replaced by hexamethylenediamine.

[0121] Comparative Example 11

[0122] This comparative example provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that the cross-linking agent is replaced with an equal mass of hexanediol glycidyl ether.

[0123] Comparative Example 12

[0124] This comparative example provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, with the only difference being that: in the preparation method of the thermally conductive plant protein-based composition, the raw materials are boron nitride, (3-(methacrylamido)propyl)trimethylammonium chloride and plant protein in a mass ratio of 1:0.2:1; the cross-linking agent is replaced by an equal mass of triglycidylamine.

[0125] Comparative Example 13

[0126] This comparative example provides a thermally conductive plant protein adhesive, which is basically the same as Example 1, except that the thermally conductive plant protein-based composition used in this comparative example is prepared by directly mixing various raw materials.

[0127] Test Example 1

[0128] This test example tested the thermally conductive plant protein adhesives obtained in the above examples and comparative examples. All tests were repeated three times, and the average value was taken.

[0129] Residual Rate Test: Weigh the mass of the filter paper and rubber band, denoted as m0. Grind the dried rubber block (passing a 100-mesh sieve) into a dry sample and place it between the stacked filter papers. Secure with a rubber band, number each sample, weigh it, and record its mass as m1. Then, completely immerse all samples in water and place them in a 60°C electric blast drying oven for 3 hours. Remove the samples from the water and place them in a 120°C electric blast drying oven for another 3 hours to determine the residual rate. After drying to constant weight, remove all samples and weigh them, recording their mass as m2. The residual rate (%) is calculated as follows: Residual rate (%) = (m2 - m0) / (m1 - m0) × 100%.

[0130] Hygroscopicity test: Folded tin foil boxes are numbered and weighed, with the mass recorded as m0. Dried samples of the dried rubber block, ground (passed through a 100-mesh sieve), are then placed into the corresponding numbered tin foil boxes. The total mass of the sample and tin foil box is weighed, recorded as m1. All assembled samples are placed in a vacuum drying oven at 60°C and 80% humidity for 6 hours for moisture absorption testing. After drying to constant weight, the samples are removed and weighed, with the mass recorded as m2. The moisture absorption rate (%) is calculated as follows: Moisture absorption rate (%) = (m2 - m0) / (m1 - m0) × 100%.

[0131] Flame retardant test: The thermally conductive plant protein adhesives in the examples and comparative examples were subjected to a flame retardant test. The specific operation was as follows: the modified adhesive and the particleboard prepared with the adhesive were directly ignited using an alcohol lamp, and the burning conditions of the test pieces were observed and recorded.

[0132] Mold resistance testing: The mold resistance of both liquid and cured adhesives was tested. 3.5g of liquid and fully cured powdered thermally conductive plant protein adhesive were weighed and evenly placed in a disposable Teflon petri dish. The dish was then placed in a constant temperature and humidity chamber at 30°C and 80% relative humidity. Each set of thermally conductive plant protein adhesives was observed every 12 hours, and their status was recorded using a camera.

[0133] 3g of uncured and cured thermally conductive plant protein adhesive were placed in a 5mm diameter plastic Petri dish and a tin foil container, respectively. The adhesive in the tin foil container was first cured in a 120°C oven and then stored in a desiccator at 30°C and 90% relative humidity. The surface morphology of the adhesive was observed and recorded.

[0134] The test results are shown in Table 1.

[0135]

[0136] Test Example 2

[0137] In this test example, three-layer plywood was prepared using the thermally conductive plant protein adhesive obtained in the above embodiments and comparative examples to test the bonding strength.

[0138] Poplar veneer: moisture content dried to 10%; size 40 cm × 40 cm × 0.15 cm.

[0139] According to the following normal preparation process:

[0140] Gluing: Glue coating amount is 400 g / m 2 .

[0141] Hot pressing conditions: pressure 1.0 MPa, temperature 120 °C, time 8 minutes.

[0142] The performance of cross-jointed wood products was tested according to GB / T17657-1999 "Test methods for physical and chemical properties of wood-based panels and veneer wood-based panels". All plywood samples were measured six times and the average value was taken. The test results are shown in Table 2.

[0143] Thermal conductivity test: The particleboard prepared with adhesive was tested. The thermal conductivity of the material was tested using the transient plate heat source method (TPS2500S, Hot Disk) that complies with the ISO22007-2 standard. Test parameters: probe output power of 34mW, test temperature of 55℃, sample size of 20 mm × 20 mm × 3 mm. Three copies of each sample were prepared for measurement to reduce experimental errors. The thermal diffusion test was carried out using a photothermal heating system / infrared thermal imaging. The particleboard material with a size of 25 mm × 25 mm × 5 mm was heated to 58℃ on a heating table, and the temperature changes of the three materials over time were recorded. The test results are shown in Tables 2 and Figure 1 .

[0144]

[0145] Table 1, Table 2 and Figure 1 The experimental results show that the bonding strength, thermal conductivity, flame retardancy and mildew resistance of the thermally conductive plant protein adhesive provided by the present invention are far superior to those of ordinary plant protein adhesives. This shows that the plant protein matrix modified by graphene, (3-(methacrylamido)propyl)trimethylammonium chloride and sodium dodecyl sulfate in the present invention improves the interfacial effect of plant protein and gives the adhesive good thermal conductivity and mildew resistance; the flame retardant enhancer prepared by using succinic anhydride, diethylenetriamine and hexachlorocyclotriphosphazene has good flame retardancy, and the cross-linking agent prepared by using p-dimethylaminobenzaldehyde and hexachlorocyclotriphosphazene is cross-linked with the thermally conductive plant protein-based composition and the flame retardant enhancer through Schiff base reaction, which synergistically increases the cross-linking density of the thermally conductive plant protein adhesive, improves the bonding strength of the thermally conductive plant protein adhesive, and improves the water resistance of the thermally conductive plant protein adhesive.

[0146] The thermally conductive plant protein adhesive provided by the embodiments of the present invention and / or the thermally conductive plant protein adhesive obtained by the preparation method are suitable for the artificial board industry, thermal management and energy storage material fields due to their excellent bonding strength, thermal conductivity, flame retardancy and mildew resistance.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A thermally conductive plant protein adhesive, characterized in that: The raw materials include 6-20 wt% of a thermally conductive plant protein-based composition, 3-8 wt% of a cross-linking agent, and 0.1-3 wt% of a flame retardant reinforcing agent; The thermally conductive plant protein-based composition is obtained by ball milling raw materials including a thermally conductive filler, a modified plant protein, and (3-(methacrylamido)propyl)trimethylammonium chloride in a mass ratio of 1:(0.3-5):(0.03-1) for 15-25 hours; The modified plant protein is obtained by modification with a modifying agent; The modifier is selected from at least one of sodium lauryl sulfate, urea and guanidine hydrochloride; The thermally conductive filler is selected from at least one of graphene, boron nitride, and carbon nanotubes; The cross-linking agent is prepared by nucleophilic reaction of hexachlorocyclotriphosphazene and p-dimethylaminobenzaldehyde in a molar ratio of 1: (2-5); The flame retardant reinforcing agent is obtained by cross-linking reaction of succinic anhydride, diethylenetriamine and hexachlorocyclotriphosphazene; The preparation method of the thermally conductive plant protein adhesive comprises: (1) uniformly mixing the heat-conductive plant protein-based composition with a dispersion medium; (2) Add the cross-linking agent and mix evenly to obtain the thermal conductive plant protein adhesive.

2. The thermally conductive plant protein adhesive according to claim 1, characterized in that: The raw materials of the thermally conductive plant protein-based composition include the thermally conductive filler, modified plant protein and (3-(methacrylamido)propyl)trimethylammonium chloride in a mass ratio of 1:(1-3):(0.2-0.6).

3. The thermally conductive plant protein adhesive according to claim 1, characterized in that: The modified plant protein is prepared from raw materials comprising plant protein and a modifier in a mass ratio of (15-18):(0.9-1.2).

4. The thermally conductive plant protein adhesive according to claim 3, characterized in that: The modified plant protein is prepared from raw materials comprising plant protein and a modifier in a mass ratio of 15:(0.9-1.2).

5. The thermally conductive plant protein adhesive according to claim 3, characterized in that: Preparation method of modified plant protein: the reaction temperature is 25-30° C., and / or the reaction time is 1-3 hours.

6. The thermally conductive plant protein adhesive according to claim 3, characterized in that: The plant protein is selected from at least one of soy protein, corn protein, peanut protein, pea protein and rice protein.

7. The thermally conductive plant protein adhesive according to claim 1, characterized in that: The particle size of the thermal conductive filler is 3-5 μm.

8. The thermally conductive plant protein adhesive according to claim 1, characterized in that: The ball milling speed is 500-800 rpm.

9. The thermally conductive plant protein adhesive according to claim 1, characterized in that: The raw materials include 12-16 wt% of the heat-conductive plant protein-based composition and 3-6 wt% of a cross-linking agent.

10. The thermally conductive plant protein adhesive according to claim 1, characterized in that: The time of the nucleophilic reaction is 3-6 hours; and / or the temperature of the nucleophilic reaction is 30-50°C.

11. The thermally conductive plant protein adhesive according to claim 1, characterized in that: Its raw materials include 1-2wt% of a flame retardant reinforcing agent.

12. The thermally conductive plant protein adhesive according to claim 1, characterized in that: The cross-linking reaction of the flame retardant reinforcing agent includes a first-stage reaction, a second-stage reaction and a third-stage reaction: The first stage reaction is: succinic anhydride and diethylenetriamine in a molar ratio of 1: (0.5-1) are reacted at a temperature of 30-50 ° C for 3-5 hours; The second stage reaction comprises: continuing the reaction at a temperature of 120-150° C. for 3-6 hours to obtain a reaction product H; The third stage reaction is: the reaction product H and hexachlorocyclotriphosphazene in a molar ratio of 1: (0.1-0.3) are reacted at a temperature of 60-90° C. for 13-16 hours.

13. A method for preparing the thermally conductive plant protein adhesive according to any one of claims 1 to 12, characterized in that: include: (1) uniformly mixing the heat-conductive plant protein-based composition with a dispersion medium; (2) Add the cross-linking agent and mix evenly to obtain the thermal conductive plant protein adhesive.

14. The method for preparing the thermally conductive plant protein adhesive according to claim 13, characterized in that: In the step (2), the flame retardant reinforcing agent is first added and mixed evenly; and then the cross-linking agent is added.

15. The method for preparing the thermally conductive plant protein adhesive according to claim 13, characterized in that: The dispersion medium is water.

16. The method for preparing the thermally conductive plant protein adhesive according to claim 15, characterized in that: The water is selected from at least one of tap water, softened water and distilled water.

17. Use of the thermally conductive plant protein adhesive according to any one of claims 1 to 12 in the fields of wood-based panel industry, thermal management and energy storage materials.

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