Heat-conducting vegetable protein-based adhesive as well as preparation method and application thereof

Abstract

The invention provides a heat-conducting vegetable protein-based composition, a heat-conducting vegetable protein adhesive as well as a preparation method and application of the heat-conducting vegetable protein-based composition and the heat-conducting vegetable protein adhesive. The heat-conducting vegetable protein-based composition provided by the invention is prepared by ball-milling raw materials including a heat-conducting filler, modified vegetable protein and (3-(methacrylamido) propyl) trimethyl ammonium chloride in a mass ratio of 1: (0.3-5): (0.03-1) for 15-25 hours. The heat-conducting vegetable protein adhesive comprises the following raw materials in percentage by weight: 6-20% of the heat-conducting vegetable protein-based composition and 3-8% of a cross-linking agent, and further comprises 0.1-3% of a flame-retardant reinforcing agent on the basis of the heat-conducting vegetable protein-based composition and the cross-linking agent. The heat-conducting vegetable protein adhesive provided by the invention adopts the heat-conducting vegetable protein-based composition, has good cementing performance and water resistance, also has good heat conductivity, flame retardance and mildew resistance, is beneficial to preparation of multifunctional materials, and is beneficial to industrial application, 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] Precious wood resources are relatively scarce, while plantation resources are abundant. Therefore, the use of fast-growing plantation wood combined with adhesives to prepare artificial boards has become the main choice for manufacturing furniture, flooring and interior decorations. The output of artificial boards is large and most of them are plywood products, among which aldehyde resins and their modified products are the main adhesives.

[0003] In recent years, soy protein adhesives have received widespread attention as a potential substitute for formaldehyde-based resins. The research on soy protein adhesives in the field of wood-based panel production has been continuously deepened, which will help reduce formaldehyde pollution in the human living environment and promote sustainable development. With the improvement of living standards, people's demand for wood composite materials with multifunctional properties such as flame retardancy, mildew resistance and thermal conductivity is increasing. In adhesives and their composites, thermal conductivity not only plays a key role in the field of thermal management, but also has important significance for the research and development of geothermal floors and energy storage biocomposites. However, it is still a challenge to improve the water resistance of soy protein adhesives while giving them flame retardancy, mildew resistance and thermal conductivity, which requires 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 dodecyl sulfate), which can fully disperse and expand the soybean protein, expose more polar and non-polar groups, and lay 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 between the soybean proteins is increased, so that the water resistance is improved, and it also has the advantages of The effect of preserving the finished product; finally, the modifier is added for further modification, which increases the number of reactive groups in the reaction system. A large number of amino, hydroxyl and other reactive groups on the soybean protein can react with the modifier under acidic conditions and form cross-linking, which reduces the number of hydrophilic groups and improves water resistance. On the other hand, the modifier will also self-polymerize in the reaction system. After the adhesive layer is cured, a denser network structure with a higher degree of cross-linking than ordinary untreated protein adhesives is formed, which enhances 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 modifiers can effectively enhance the initial viscosity of soybean protein adhesives, improve the interface compatibility between adhesives and boards, and enhance the bonding effect.

[0005] The water-resistant soy protein-based adhesive provided in the above prior art has the problems of insufficient thermal conductivity and high heat transfer inertia when used, which may lead to poor performance in the field of heat conduction (such as thermal conductive floors) and fail to meet the use requirements. 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 to 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 treatment method is adopted, 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 thermally conductive adhesive finally obtained 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 a 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 by reacting in the presence of a solvent (such as water); the reaction temperature is 25-30°C, the reaction time is 1-3h, and it is carried out under stirring conditions, for example, the stirring rate is 200-300 rmp, and the freeze-drying time is 5-10h.

[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 dodecyl 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 dodecyl sulfate) and plant protein. The modification of the plant protein by the modifier (such as sodium dodecyl sulfate) effectively promotes the exposure of active functional groups in the plant protein. This modification strategy significantly improves 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 path in the thermally conductive adhesive system, thereby significantly optimizing the 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, especially graphene, the thermally conductive plant protein-based composition can better 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] The 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 rate is 500-800 rmp, 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, and 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, and the compatibility with the plant protein is well achieved. Not only does it play a physical filling role in the adhesive system, but also due to the good thermal conductivity of the thermally conductive filler (such as graphene), a stable and continuous thermal conductive path can be formed in the wood composite material prepared by the plant protein adhesive, thereby giving the plant protein adhesive thermal conductivity, which is beneficial to 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 beneficial to improving the interface interaction between the thermally conductive filler (such as graphene) and the plant protein, promoting the formation of a thermal conductive path 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, and 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, to provide a thermally conductive plant protein adhesive, 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 desired 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, exceeding 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 uses a simple Schiff base reaction to efficiently crosslink the crosslinking agent with the flame retardant enhancer and the protein adhesive system. The hyperbranched aldehyde groups contained in the crosslinking agent are evenly distributed in the protein adhesive system to form chemical bonds, thereby constructing a stable crosslinked network structure and improving the adhesive bonding performance and water resistance of the adhesive. In particular, the ratio of the flame retardant enhancer to the crosslinking agent is in the range of (0.1-3): (3-8), especially (1-2): (3-6), which can achieve the effect of synergistically 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, wherein the continued reaction is carried out 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 for 13-16 hours at a temperature of 60-90°C and a stirring rate of 200-400 rmp; the flame retardant enhancer is obtained.

[0034] The thermally conductive plant protein adhesive provided by the present invention adopts the flame retardant enhancer prepared by the reaction of 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: 6-20wt% of the thermally conductive plant protein-based composition, 0.3-3wt% of the flame retardant enhancer, 3-8wt% of the cross-linking agent and the balance of dispersion medium.

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

[0037] The fourth object of the present invention is to provide a method for preparing the aforementioned thermally conductive plant protein adhesive, comprising the following steps: (1) uniformly mixing the thermally conductive plant protein-based composition and a dispersion medium; (2) Add the cross-linking agent and mix evenly to obtain the thermal conductive plant protein adhesive.

[0038] In some embodiments of the present invention, in the step (2), the flame retardant reinforcing agent is first added and mixed evenly; and then the cross-linking agent is added.

[0039] In some embodiments of the present invention, the dispersion medium is water.

[0040] In some embodiments of the present invention, the water is selected from at least one of tap water, softened water, and distilled water.

[0041] The fifth object of the present invention is to provide an application of the aforementioned thermally conductive plant protein adhesive in the fields of wood-based panel industry, thermal management and energy storage materials.

[0042] In some embodiments of the present invention, a man-made board is provided, wherein the man-made board adopts the aforementioned thermally conductive plant protein adhesive, for example, a three-layer plywood obtained by gluing the aforementioned thermally conductive plant protein adhesive.

[0043] The present invention has the following beneficial effects: (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; (2) The thermally conductive plant protein adhesive provided by the present invention is conducive to achieving stress balance in the preparation of plywood and improving its bonding performance; (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; (4) The thermally conductive plant protein adhesive provided by the present invention does not contain any toxic substances, and the components are matched in reasonable amounts. The synthetic adhesive has high efficiency, does not release any harmful substances, has high product reactivity, good processability, stable performance in each batch, and low cost, which is conducive to industrial application.

[0044] Experiments have shown that the thermally conductive plant protein adhesive provided by the present invention is easy to form a cross-linked structure, has a large cross-linking density, a simple synthesis process, excellent thermal conductivity, flame retardancy and mildew resistance, and the prepared plywood has stable performance, a significantly reduced weak interface layer, good dry strength, good water-resistant bonding performance, and stable product quality. The thermally conductive plant protein adhesive provided by the present invention can meet the requirements of water resistance and multifunctionality of adhesives for plywood, and ensure the practical performance of biomass adhesives and their preparation of wood composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces 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 creative work.

[0046] 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

[0047] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are all commercially available unless otherwise specified.

[0049] In the present invention, if the percentage sign "%" is involved, it refers to mass percentage unless otherwise specified; 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 ratio of the volumes at 20°C.

[0050] The water used in the embodiments of the present invention is tap water.

[0051] The vegetable 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 meshes.

[0052] The modifier used in the embodiment of the present invention is sodium dodecyl sulfate, and the molecular weight is 288.4.

[0053] The thermal conductive filler used in the embodiment of the present invention is graphene, and the average particle size is 300 meshes.

[0054] The molecular weight of (3-(methacrylamido)propyl)trimethylammonium chloride used in the examples of the present invention is 206.7.

[0055] The molecular weight of the hexachlorocyclotriphosphazene used in the examples of the present invention is 348.

[0056] The molecular weight of succinic anhydride used in the examples of the present invention is 100.

[0057] The molecular weight of diethylenetriamine used in the examples of the present invention is 103.

[0058] The molecular weight of p-dimethylaminobenzaldehyde used in the examples of the present invention is 149.2.

[0059] The preparation method of the thermally conductive plant protein adhesive provided by the present invention comprises: (1) placing 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 in a beaker, mixing 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-drying for 5-10 hours to obtain a modified vegetable protein; (2) placing 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 in a ball mill, and mixing at a ball milling rate of 650-700 rpm (e.g., 22-24 hours) until the mixture is uniform, to obtain a thermally conductive plant protein-based composition; (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; (4) Add 1-2 parts by weight of the flame retardant enhancer to the system and stir (e.g., 10-15 minutes) until the solution is uniform and stable; (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 thermally conductive plant protein adhesive.

[0060] Preferably, the total weight parts of the above raw materials is 100 parts, that is, the usage of the above weight parts can also be directly expressed as mass percentage, and in the following embodiments, 1 part = 1g.

[0061] Example 1 This embodiment provides a thermally conductive plant protein-based composition, and the preparation method thereof is as follows: (A) Preparation of modified vegetable protein: 15 g of vegetable protein, 80 g of water and 1 g of sodium dodecyl sulfate were placed in a beaker, and the mixture was reacted for 2 h at a stirring rate of 250 rpm and a reaction temperature of 25° C. The obtained solution was freeze-dried for 6 h to obtain the modified vegetable protein; (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 are put into a beaker and subjected to mechanical ball milling at a rate of 650 rpm and a temperature of 30° C. for 24 h to obtain the thermally conductive plant protein-based composition.

[0062] 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: (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 reacted for 3 hours at a stirring rate of 400 rpm and a temperature of 30° C. to obtain the cross-linking agent; (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: The first stage reaction: the reaction was carried out for 3 h at a stirring rate of 300 rpm and a temperature of 50 °C; The second stage of reaction: the temperature was raised to 140°C, the stirring rate was 400 rmp, and the reaction was continued for 3 h to obtain the reaction product H; The third stage reaction: 0.2 mol of hexachlorocyclotriphosphazene and 1 mol of the reaction product H are placed in a three-necked flask equipped with a stirrer, and the reaction is carried out for 15 hours at a temperature of 70° C. and a stirring rate of 400 rpm to obtain the flame retardant enhancer; (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 is uniform and stable; (4) Add 1.5 g of the flame retardant enhancer prepared in step (2) into the system and stir for 15 min until the solution is uniform and stable; (5) Continue to add 4 g of the cross-linking agent prepared in step (1) into the system and continue stirring for 10 min to obtain the thermally conductive plant protein adhesive.

[0063] Example 2 This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Embodiment 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.

[0064] Example 3 This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Embodiment 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.

[0065] Example 4 This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Embodiment 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.

[0066] Example 5 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.

[0067] Example 6 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.

[0068] Example 7 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.

[0069] Example 8 This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Embodiment 1, except that, in the preparation method of the cross-linking agent, the mass ratio of the hexachlorocyclotriphosphazene to p-dimethylaminobenzaldehyde is 1:2.

[0070] Example 9 This embodiment provides a thermally conductive plant protein adhesive, which is basically the same as Embodiment 1, except that, in the preparation method of the cross-linking agent, the mass ratio of the hexachlorocyclotriphosphazene to p-dimethylaminobenzaldehyde is 1:5.

[0071] Comparative Example 1 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.

[0072] Comparative Example 2 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.

[0073] Comparative Example 3 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 by sodium dodecyl sulfate.

[0074] Comparative Example 4 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.

[0075] Comparative Example 5 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 method for preparing 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.

[0076] Comparative Example 6 This comparative example provides an adhesive, which is a common E0 grade urea-formaldehyde resin adhesive (purchased from Shandong Qiansen Wood Industry Co., Ltd.).

[0077] Comparative Example 7 This comparative example provides a plant protein adhesive, and the preparation steps are as follows: 15g of soy protein is added into 85g of water, and stirred for 20 minutes to obtain the plant protein adhesive.

[0078] Comparative Example 8 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 polyamide epichlorohydrin cross-linking agent is added to obtain a thermally conductive plant protein adhesive.

[0079] Comparative Example 9 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.

[0080] Comparative Example 10 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.

[0081] Comparative Example 11 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.

[0082] Comparative Example 12 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; and the cross-linking agent is replaced by an equal mass of triglycidylamine.

[0083] Comparative Example 13 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.

[0084] Test Example 1 This test example tests the thermally conductive plant protein adhesives obtained in the above embodiments and comparative examples. All tests are repeated three times and the average value is taken.

[0085] Residual rate test: weigh the mass of the filter paper and rubber band, record it as m0, put the dried rubber block into the folded filter paper, tie it with a rubber band, number and weigh it respectively, record the mass as m1, then immerse all the samples completely in water, place them in an electric blast drying oven at 60℃ for 3h, then take the samples out of the water and place them in an electric blast drying oven at 120℃ to continue the residual rate determination experiment for 3h. After drying to constant weight, take out all the samples and weigh them, record the mass as m2. The residual rate (%) is calculated as follows: residual rate (%) = (m2-m0) / (m1-m0) × 100%.

[0086] Hygroscopicity test: The folded tin foil boxes are numbered and weighed, and the mass is recorded as m0. Then the dried rubber blocks are ground (passed through a 100-mesh sieve) into dry samples and placed in the corresponding numbered tin foil boxes. The total mass of the samples and tin foil boxes is weighed and recorded as m1. All the loaded samples are placed in a vacuum drying oven at 60°C and 80% humidity for a moisture absorption test for 6 hours. After drying to constant weight, the samples are taken out and weighed, and the mass is recorded as m2. The moisture absorption rate (%) is calculated as follows: Moisture absorption rate (%) = (m2-m0) / (m1-m0) × 100%.

[0087] Flame retardant test: The thermally conductive plant protein adhesives in the examples and comparative examples were subjected to flame retardant tests. The specific operation was as follows: the modified adhesive and the particleboard prepared with the adhesive were directly ignited by an alcohol lamp, and the burning conditions of the test pieces were observed and recorded.

[0088] Mildew resistance test: Test the mildew resistance of liquid adhesive and cured adhesive respectively. Weigh 3.5g of the liquid thermally conductive plant protein adhesive and the fully cured powdered thermally conductive plant protein adhesive respectively and place them evenly in a disposable polytetrafluoroethylene culture dish; then place them in a constant temperature and humidity chamber at a temperature of 30°C and a relative humidity of 80%. Observe each group of the thermally conductive plant protein adhesive every 12 hours and record its status with a camera.

[0089] 3 g of the uncured and cured thermally conductive plant protein adhesive were placed in a plastic petri dish and a tin foil box with a diameter of 5 mm, respectively. The thermally conductive plant protein adhesive in the tin foil box was first cured in an oven at 120° C. and then stored in a desiccator at a temperature of 30° C. and a relative humidity of 90%. The surface morphology of the thermally conductive plant protein adhesive was observed and recorded.

[0090] The test results are shown in Table 1.

[0091] Test Example 2 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.

[0092] Poplar veneer: moisture content dried to 10%; size 40 cm×40 cm×0.15 cm.

[0093] According to the following normal preparation process: Gluing: Glue coating amount is 400 g / m 2 .

[0094] Hot pressing conditions: pressure 1.0 MPa, temperature 120 °C, time 8 min.

[0095] The performance of cross-joined 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.

[0096] 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 is 34mW, test temperature is 55℃, and sample size is 20 mm × 20 mm × 3 mm. Three copies of each sample were prepared for measurement to reduce experimental errors. A photothermal heating system / infrared thermal imaging was used for thermal diffusion tests. The particleboard of the 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 .

[0097] 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. It is explained 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.

[0098] 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 is suitable for the artificial board industry, thermal management and energy storage material fields due to its excellent bonding strength, thermal conductivity, flame retardancy and mildew resistance.

[0099] 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 embodiments of the present invention.

Claims

1. A thermally conductive plant protein-based composition, characterized in that: The material is obtained by ball milling raw materials including a thermal conductive filler, modified vegetable protein and (3-(methacrylamide)propyl)trimethylammonium chloride in a mass ratio of 1:(0.3-5):(0.03-1) for 15-25 hours.

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

3. The thermally conductive plant protein-based composition according to claim 1 or 2, characterized in that: The modified plant protein is obtained by modification with a modifying agent; Preferably, it is prepared from raw materials comprising vegetable protein and a modifier in a mass ratio of (15-18):(0.9-1.2); Preferably, the modified vegetable protein is prepared from raw materials including vegetable protein and a modifier in a mass ratio of 15:(0.9-1.2); Preferably, in the preparation method of the modified plant protein, the reaction temperature is 25-30°C, and / or the reaction time is 1-3h; Preferably, the plant protein is selected from at least one of soy protein, corn protein, peanut protein, pea protein and rice protein; Preferably, the modifier is selected from at least one of sodium dodecyl sulfate, urea and guanidine hydrochloride.

4. The thermally conductive plant protein-based composition according to any one of claims 1 to 3, characterized in that: The thermally conductive filler is selected from at least one of graphene, boron nitride and carbon nanotubes; the particle size of the thermally conductive filler is 3-5 μm.

5. The method for preparing the thermally conductive plant protein-based composition according to any one of claims 1 to 4, characterized in that: The ball milling speed is 500-800 rpm.

6. A thermally conductive plant protein adhesive, characterized in that: The raw materials include 6-20 wt % of the heat-conductive plant protein-based composition according to claim 5 and 3-8 wt % of a cross-linking agent.

7. The thermally conductive plant protein adhesive according to claim 6, characterized in that: The raw materials include 12-16 wt% of the thermally conductive plant protein-based composition and 3-6 wt% of a cross-linking agent; Preferably, the cross-linking agent is prepared by nucleophilic reaction of hexachlorocyclotriphosphazene and p-dimethylaminobenzaldehyde in a molar ratio of 1: (2-5); Preferably, the time of the nucleophilic reaction is 3-6 h; and / or the temperature of the nucleophilic reaction is 30-50°C.

8. The thermally conductive plant protein adhesive according to claim 6 or 7, characterized in that: The raw materials also include 0.1-3wt% of a flame retardant reinforcing agent, preferably 1-2wt% of a flame retardant reinforcing agent; Preferably, 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: Preferably, 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 3-5h; Preferably, 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; Preferably, 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.

9. The method for preparing the thermally conductive plant protein adhesive according to any one of claims 6 to 8, characterized in that: include: (1) uniformly mixing the thermally conductive plant protein-based composition and a dispersion medium; (2) adding the cross-linking agent and mixing evenly to obtain the thermally conductive plant protein adhesive; Preferably, in step (2), the flame retardant reinforcing agent is first added and mixed evenly; then the cross-linking agent is added; Preferably, the dispersion medium is water; Preferably, the water is selected from at least one of tap water, softened water and distilled water.

10. Application of the thermally conductive plant protein adhesive according to any one of claims 6 to 8 or the thermally conductive plant protein adhesive obtained by the preparation method according to claim 9 in the fields of wood-based panel industry, thermal management and energy storage materials.

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