Highly water-resistant and pre-pressing formaldehyde-free wood adhesive, preparation method and application thereof

Abstract

The application discloses a high-water-resistance high-precompression formaldehyde-free wood adhesive as well as a preparation method and application thereof, and belongs to the technical field of adhesive preparation. The wood adhesive is first synthesized by using tetraethyl orthosilicate and dodecyl trimethoxysilane to synthesize polysiloxane with a hydrophobic long chain. Tannic acid is selected as a skeleton to enhance wet bonding, and polyamide polyamine epichlorohydrin is selected as a polymer long chain to perform chain winding to enhance cohesive force and surface adhesion. Through multiple hydrogen bonds, electrostatic action and covalent bonds, a polymer high-water-resistance high-precompression formaldehyde-free adhesive is synthesized. In a humid or underwater environment, the hydrophobic chain can repel water molecules, so that the adhesive fully contacts the surface of a base material, and a protective film is formed on the surface of the adhesive to prevent erosion of water molecules. The adhesive can realize normal-temperature instantaneous adhesion, has strong water resistance, durability, acid and alkali resistance and excellent temperature adaptability, can resist ultraviolet rays, and can effectively bond even in a strong oxidizing solution.

Description

Technical Field

[0001] This invention relates to the field of adhesive preparation technology, and in particular to a high water-resistant, high pre-compression formaldehyde-free wood adhesive, its preparation method, and its application. Background Technology

[0002] Statistics show that the wood industry consumes approximately three-quarters of all adhesives, making it an indispensable material for modern industrial development. Therefore, developing wood adhesives with high stability and strength is a crucial research area. Due to the shrinking and swelling properties of wood, bonding often requires high moisture content to ensure bonding quality, such as in rotary-cut veneers and plywood. Because wood's main chemical components are rich in hydroxyl groups, they have a high affinity for water; simultaneously, the porous structure of wood accelerates moisture absorption. Therefore, in humid environments, a hydration film easily forms on the wood surface, hindering adhesive penetration and bonding, preventing rapid and effective adhesion. Consequently, ordinary wood adhesives suffer from poor water resistance and difficulty in wet or underwater bonding. For wet wood with high moisture content, direct gluing is not possible; pre-drying is generally required. Otherwise, the wood is prone to bubbling and deformation, and the adhesive cannot penetrate effectively, greatly limiting the application range of wood and its adhesives.

[0003] Traditional adhesives, such as cyanoacrylates, polyvinyl alcohols, and aldehyde resins, possess excellent dry-state bonding properties, but they cannot cure at room temperature and require hot pressing. They quickly lose their effectiveness in water, and aldehyde resins pose significant health and environmental hazards. Currently, wet or underwater adhesives are mainly developed using biomimetic strategies, such as organic-inorganic hybrid crosslinking, genetic engineering, and polyelectrolytes. However, these methods suffer from high raw material costs, long preparation cycles, limited mechanical strength, complex formulation design, and uneven stress distribution. Furthermore, adhesives specifically designed for wet and underwater bonding of wood are very limited. Therefore, developing a formaldehyde-free wood adhesive with high water resistance, high pre-compression capability, and versatility in various environments is of great significance. Summary of the Invention

[0004] To address the technical problems of existing wood adhesives being water-insensitive and difficult to cure at room temperature, this invention provides a highly water-resistant, high-pre-compression, formaldehyde-free wood adhesive, its preparation method, and its application. The adhesive prepared by this invention can bond wood in a wet state and underwater, achieving room temperature curing, and exhibits excellent bonding strength after curing.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] On the one hand, the present invention provides a method for preparing a high water-resistant, high pre-compression formaldehyde-free wood adhesive. First, tetraethyl orthosilicate and dodecyltrimethoxysilane are dehydrated and condensed to form a hydrophobic polysiloxane, which plays a role in hydrophobicity and enhancing cohesion in the system. Then, it is mixed with tannic acid and polyamide polyamine epichlorohydrin. Through covalent bonds, multiple hydrogen bonds and electrostatic interactions, a wood adhesive with high water resistance and high pre-compression properties is obtained.

[0007] Specifically, the preparation method of the above-mentioned high water resistance, high pre-compression formaldehyde-free wood adhesive includes the following steps:

[0008] (1) Tetraethoxysilane (TEOS) and dodecyltrimethoxysilane (12-TMOS) with a molar ratio of 1:0.05-0.3 are placed in a three-necked flask, and ethanol, water, and hydrochloric acid are added to the flask. After hydrolysis and condensation at 60-80 °C for 2-6 h, the reaction product is obtained; in step (1), the mass of ethanol is equal to that of TEOS, and the molar mass of water is the sum of 4 times the molar mass of TEOS and 3 times the molar mass of 12-TMOS; the amount of hydrochloric acid used is 2-5 drops, and the pH value is adjusted to be maintained between 3 and 4 using hydrochloric acid;

[0009] (2) The reaction product was dried in a vacuum drying oven at 35 °C for 12 h to remove excess ethanol and water, yielding a hydrophobic polysiloxane system:

[0010] (3) Pour polyamide polyamine epichlorohydrin aqueous solution into the flask, and add tannic acid and hydrophobic polysiloxane system. Stir at 200-300 rpm for 5 min at room temperature until a uniform solid gel is formed; the mass ratio of polyamide polyamine epichlorohydrin aqueous solution, tannic acid and hydrophobic polysiloxane system in step (3) is 5:1:0.05-0.5;

[0011] (4) Place the solid gel into a centrifuge tube, centrifuge at 3000-5000 rpm for 5-10 min, and discard the supernatant to obtain a high water-resistant, high pre-compression formaldehyde-free wood adhesive. The obtained adhesive should be sealed and stored.

[0012] The hydrophobic chains in the high water-resistant, high pre-compression formaldehyde-free wood adhesive prepared in this invention form a protective film on the adhesive surface, which can repel water molecules on the substrate and prevent water erosion; it also exposes a large number of hydrophilic adhesion factors, increasing the contact area between the adhesive and the substrate. The cohesive strength of the high water-resistant, high pre-compression formaldehyde-free wood adhesive of this invention is mainly provided by covalent bonds, hydrogen bonds, and electrostatic interactions; it can interact with the substrate material through electrostatic interactions, van der Waals forces, hydrogen bonding, mechanical interlocking, and chemical bonding. A schematic diagram of the reaction process and the cohesive strength of the prepared adhesive is shown below. Figure 1-3 As shown.

[0013] The wood adhesive of this invention can be cured at room temperature (normal temperature, 1 MPa pressure, application rate 180 g / cm³). 3 It achieves instant adhesion under cold pressure, can be used in various harsh underwater environments, and can be applied to the preparation of wet wood plywood or the repair of underwater wood structures.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) The present invention provides a high water resistance, high pre-pressure formaldehyde-free wood adhesive. Due to the long-chain alkyl of dodecyltrimethoxysilane, it has strong hydrophobicity, which will destroy the hydration layer on the surface of the substrate, so that the adhesive can fully contact the base material. At the same time, due to the soft characteristics of the long chain, after bonding, the hydrophobic long chain will cover the adhesive layer to form a protective layer, preventing water molecules from eroding and maintaining long-term adhesion.

[0016] (2) This invention provides a highly water-resistant, high-pre-compression, formaldehyde-free wood adhesive that can be cured at room temperature and in water, has high pre-compression properties, and can achieve instant adhesion of wood. Even in complex and harsh aquatic environments such as salt water solutions, including a wide pH range (pH: 3-11), extreme temperatures (0-100 ℃), strong ultraviolet radiation, and strong oxidizing conditions, it still maintains excellent adhesion performance.

[0017] (3) The present invention provides a high water resistance, high pre-compression formaldehyde-free wood adhesive with a simple preparation process, short cycle, relatively low raw material price, and can be prepared in large quantities at one time, and has broad underwater application prospects. Attached Figure Description

[0018] Figure 1 The reaction equation for step one of Embodiment 1 of the present invention;

[0019] Figure 2 The reaction equation for the hydrophobic siloxane system and tannic acid in step three of Example 1 of this invention is as follows:

[0020] Figure 3 This is a schematic diagram of the intermolecular forces between polyamide polyamine epichlorohydrin and other substances in the system in Example 1 of the present invention;

[0021] Figure 4 This is a schematic diagram illustrating the specific process of overlapping the adhesive of the present invention underwater.

[0022] Figure 5 (a) Shear strength diagrams of different substrates at different times; (b) Shear strength diagrams of different substrates under ultraviolet light conditions; (c) Shear strength diagrams of different substrates under oxidation conditions. Detailed Implementation

[0023] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with specific embodiments.

[0024] All reagents and materials used in this invention, unless otherwise specified, are commercially available. Among them, the polyamide polyamine epichlorohydrin is a water-soluble PAE powder from a certain company, with a degree of polymerization of 800.

[0025] This invention provides a high water-resistant, high-pre-compression, formaldehyde-free wood adhesive, its preparation method, and its application. Specific embodiments are as follows.

[0026] Example 1

[0027] A method for preparing a high water-resistant, high-pre-compression, formaldehyde-free wood adhesive includes:

[0028] Step 1: Place 10.4 g of tetraethoxysilane and 4.36 g of dodecyltrimethoxysilane in a three-necked flask, and add 10.4 g of ethanol, 4.41 g of water and 3 drops of hydrochloric acid to the three-necked flask. After hydrolysis and condensation at 60 °C for 4 h, the reaction product is obtained.

[0029] Step 2: The reaction product was dried in a vacuum drying oven at 35 °C for 12 h to remove excess ethanol and water, resulting in a polysiloxane hydrophobic system.

[0030] Step 3: Pour 10 g of 12% polyamide polyamine epichlorohydrin aqueous solution into the flask, add 2 g of tannic acid powder and 0.2 g of hydrophobic polysiloxane system, and stir rapidly at room temperature for 5 min until a homogeneous solid gel is formed.

[0031] Step 4: Place the solid gel into a centrifuge tube, centrifuge at 5000 rpm for 10 min, then discard the supernatant to obtain a high water-resistant, high pre-compression formaldehyde-free wood adhesive.

[0032] Example 2

[0033] A method for preparing a high water-resistant, high-pre-compression, formaldehyde-free wood adhesive includes:

[0034] Step 1: Place 10.4 g of tetraethoxysilane and 2.91 g of dodecyltrimethoxysilane in a three-necked flask, and add 10.4 g of ethanol, 4.5 g of water, and 3 drops of hydrochloric acid to the flask. Hydrolyze and condense at 80 °C for 2 h to obtain the reaction product.

[0035] Step 2: The reaction product was dried in a vacuum drying oven at 35 °C for 12 h to remove excess ethanol and water, resulting in a polysiloxane hydrophobic system.

[0036] Step 3: Pour 10 g of 12% polyamide polyamine epichlorohydrin aqueous solution into the flask, add 2 g of tannic acid powder and 0.3 g of hydrophobic polysiloxane system, and stir rapidly at room temperature for 5 min until a homogeneous solid gel is formed.

[0037] Step 4: Place the solid gel into a centrifuge tube, centrifuge at 5000 rpm for 10 min, then discard the supernatant to obtain a high water-resistant, high pre-compression formaldehyde-free wood adhesive.

[0038] Example 3

[0039] A method for preparing a high water-resistant, high-pre-compression, formaldehyde-free wood adhesive includes:

[0040] Step 1: Place 10.4 g of tetraethoxysilane and 2.91 g of dodecyltrimethoxysilane in a three-necked flask, and add 10.4 g of ethanol, 4.5 g of water, and 3 drops of hydrochloric acid to the flask. Hydrolyze and condense at 80 °C for 2 h to obtain the reaction product.

[0041] Step 2: The reaction product was dried in a vacuum drying oven at 35 °C for 12 h to remove excess ethanol and water, resulting in a polysiloxane hydrophobic system.

[0042] Step 3: Pour 10 g of 12% polyamide polyamine epichlorohydrin aqueous solution into the flask, add 2 g of tannic acid powder and 0.5 g of hydrophobic polysiloxane system, and stir rapidly at room temperature for 5 min until a homogeneous solid gel is formed.

[0043] Step 4: Place the solid gel into a centrifuge tube, centrifuge at 5000 rpm for 10 min, then discard the supernatant to obtain a high water-resistant, high pre-compression formaldehyde-free wood adhesive.

[0044] Example 4

[0045] A method for preparing a high water-resistant, high-pre-compression, formaldehyde-free wood adhesive includes:

[0046] Step 1: Place 10.4 g of tetraethoxysilane and 1.45 g of dodecyltrimethoxysilane in a three-necked flask, and add 10.4 g of ethanol, 3.87 g of water and 3 drops of hydrochloric acid to the three-necked flask. After hydrolysis and condensation at 60 °C for 4 h, the reaction product is obtained.

[0047] Steps two through four are the same as in Example 3.

[0048] Example 5

[0049] A method for preparing a high water-resistant, high-pre-compression, formaldehyde-free wood adhesive includes:

[0050] Step 1: Place 10.4 g of tetraethoxysilane and 0.73 g of dodecyltrimethoxysilane in a three-necked flask, and add 10.4 g of ethanol, 3.73 g of water and 3 drops of hydrochloric acid to the three-necked flask. After hydrolysis and condensation at 60 °C for 4 h, the reaction product is obtained.

[0051] Steps two through four are the same as in Example 3.

[0052] Example 6

[0053] A method for preparing a high water-resistant, high-pre-compression, formaldehyde-free wood adhesive includes:

[0054] Steps one and two are the same as in Example 3;

[0055] Step 3: Pour 10 g of 12% polyamide polyamine epichlorohydrin aqueous solution into the flask, add 2 g of tannic acid powder and 1 g of hydrophobic polysiloxane system, and stir rapidly at room temperature for 5 min until a homogeneous solid gel is formed.

[0056] Step four is the same as in Example 3.

[0057] Example 7

[0058] A method for preparing a high water-resistant, high-pre-compression, formaldehyde-free wood adhesive includes:

[0059] Steps one and two are the same as in Example 3;

[0060] Step 3: Place 10.4 g of tetraethoxysilane and 5.8 g of dodecyltrimethoxysilane in a three-necked flask, and add 10.4 g of ethanol, 4.68 g of water and 3 drops of hydrochloric acid to the three-necked flask. After hydrolysis and condensation at 60 °C for 4 h, the reaction product is obtained.

[0061] Step four is the same as in Example 3.

[0062] To further illustrate the beneficial effects of the present invention, the following comparative examples were constructed.

[0063] Comparative Example 1

[0064] A wood adhesive and its preparation method, comprising:

[0065] Step 1: Pour 10 g of 12% polyamide polyamine epichlorohydrin aqueous solution into the flask, add 2 g of tannic acid powder, and stir rapidly at room temperature for 5 min until a homogeneous solid gel is formed.

[0066] Step 2: Place the solid gel into a centrifuge tube, centrifuge at 5000 rpm for 10 min, then discard the supernatant to obtain a high water-resistant, high pre-compression formaldehyde-free wood adhesive.

[0067] Comparative Example 2

[0068] A wood adhesive and its preparation method, comprising:

[0069] Step 1: Pour 10 g of 12% polyamide polyamine epichlorohydrin aqueous solution into the flask, add 2 g of tannic acid powder and 1 g of tetraethoxysilane, and stir rapidly at room temperature for 5 min until a homogeneous solid gel is formed.

[0070] Step 2: Place the solid gel into a centrifuge tube, centrifuge at 5000 rpm for 10 min, then discard the supernatant to obtain a high water-resistant, high pre-compression formaldehyde-free wood adhesive.

[0071] Comparative Example 3

[0072] A wood adhesive and its preparation method, comprising:

[0073] Step 1: Pour 10 g of 12% polyamide polyamine epichlorohydrin aqueous solution into the flask, add 2 g of tannic acid powder and 1 g of dodecyltrimethoxysilane, and stir rapidly at room temperature for 5 min until a homogeneous solid gel is formed.

[0074] Step 2: Place the solid gel into a centrifuge tube, centrifuge at 5000 rpm for 10 min, then discard the supernatant to obtain a high water-resistant, high pre-compression formaldehyde-free wood adhesive.

[0075] Comparative Example 4

[0076] A wood adhesive and its preparation method, comprising:

[0077] Step 1: Pour 10 g of 12% polyamide polyamine epichlorohydrin aqueous solution into a flask, add 2 g of tannic acid powder and 1 g of silane mixture (the silane mixture is tetraethoxysilane and dodecyltrimethoxysilane in a molar ratio of 1:0.2), and stir rapidly at room temperature for 5 min until a homogeneous solid gel is formed.

[0078] Step 2: Place the solid gel into a centrifuge tube, centrifuge at 5000 rpm for 10 min, then discard the supernatant to obtain a high water-resistant, high pre-compression formaldehyde-free wood adhesive.

[0079] Comparative Example 5

[0080] In this comparative example, step one is as follows: 10.4 g of tetraethoxysilane and 7.26 g of dodecyltrimethoxysilane are placed in a three-necked flask, and 10.4 g of ethanol, 4.95 g of water and 3 drops of hydrochloric acid are added to the three-necked flask. After hydrolysis and condensation at 60 °C for 4 h, the reaction product is obtained; the remaining conditions are the same as in Example 3.

[0081] Comparative Example 6

[0082] In this comparative example, step one is as follows: 10.4 g of tetraethoxysilane and 5.8 g of dodecyltrimethoxysilane are placed in a three-necked flask, and 10.4 g of ethanol, 4.68 g of water and 3 drops of hydrochloric acid are added to the three-necked flask. After hydrolysis and condensation at 60 °C for 4 h, the reaction product is obtained; the remaining conditions are the same as in Example 3.

[0083] Comparative Example 7

[0084] In this comparative example, tannic acid powder was omitted, and the other conditions were the same as in Example 3.

[0085] Comparative Example 8

[0086] In this comparative example, step three is as follows: pour 10 g of a 12% polyamide polyamine epichlorohydrin aqueous solution into a flask, add 2 g of tannic acid powder and 2 g of hydrophobic polysiloxane system, and stir rapidly at room temperature for 5 min until a homogeneous solid gel is formed; the remaining conditions are the same as in Example 3.

[0087] Comparative Example 9

[0088] In this comparative example, step three is as follows: pour 10 g of a 12% polyamide polyamine epichlorohydrin aqueous solution into a flask, add 2 g of tannic acid powder and 1.8 g of hydrophobic polysiloxane system, and stir rapidly at room temperature for 5 min until a homogeneous solid gel is formed; the remaining conditions are the same as in Example 3.

[0089] The adhesives prepared in the above embodiments and comparative examples were subjected to performance testing, as detailed below:

[0090] First, an acidic solution (pH=3) was prepared by dissolving hydrochloric acid in distilled water; an alkaline solution (pH=11) was prepared by dissolving sodium hydroxide in distilled water. The high-temperature solution (100 ℃) was prepared by a water bath (the adhesive substrate was cured in water for 1 hour); the low-temperature solution (0 ℃) was prepared by an ice-water bath.

[0091] Prepare a wood substrate, cut the wood into 2.5×7 cm specimens, and conduct lap tensile and shear mechanical tests. Figure 4 As shown, the bonding area is 2.5 × 2.5 cm, and the adhesive application rate is 180 g / cm². 3 The tensile rate was 10 mm / min. Three parallel samples were measured under each test condition, and the average value was obtained. The specific test procedure was as follows:

[0092] 1. Determination of shear strength at different soaking times

[0093] Place the wood substrate in tap water, then apply the prepared adhesive to the wood substrate. Next, overlap another substrate onto the adhesive and secure it with dovetail clips. The process is as follows. Figure 4 The samples were soaked for 1 h, 12 h, 24 h, and 48 h, respectively, and then removed to test the shear strength after different soaking times. The results are shown in Table 1-2.

[0094] 2. Shear strength determination at different pH levels

[0095] The prepared adhesive was applied to a wood substrate, and then another substrate was overlapped onto the adhesive and fixed with dovetail clips. The specimen was then immersed in hydrochloric acid solution (pH=3) and sodium hydroxide solution (pH=11) for 24 hours. The specimen was then removed and its shear strength was tested directly. The results are shown in Table 1-2.

[0096] 3. Shear strength determination at different temperatures

[0097] The prepared adhesive was applied to a wood substrate, and then another wood substrate was used to cover the adhesive. The substrate was then fixed with dovetail clips and placed directly into water at different temperatures for 24 hours. The shear strength was then tested, and the results are shown in Table 1-2.

[0098] Table 1

[0099]

[0100] As described above, the adhesive prepared by this invention achieves a shear strength of 0.35 MPa after curing in water at room temperature for 1 hour, and 1.37 MPa after curing at room temperature for 48 hours. Even in complex and harsh aquatic environments such as saline solutions, including a wide pH range (pH: 3-11) and extreme temperatures (0-100 ℃), the adhesive prepared by this invention still exhibits high shear strength. After being sealed and stored for two months, the adhesive effect remains almost unchanged, and the underwater shear strength reaches 3.45 MPa after 6 months.

[0101] Table 2

[0102]

[0103] As can be seen from the above description, omitting the hydrophobic polysiloxane system, changing the ratio of tetraethoxysilane to dodecyltrimethoxysilane, or changing the ratio of polyamide polyamine epichlorohydrin, tannic acid, and the hydrophobic polysiloxane system will significantly reduce the shear strength of the prepared adhesive.

[0104] The inventors also conducted shear tests on different substrates, using steel, glass, rubber, PMMA, PE, PTFE, PVA, and PVC as substrates. These substrates were prepared into samples identical to those used for wood, then coated with the adhesive described in Example 6, overlapped, and secured with dovetail clips. The samples were then soaked in tap water for 10, 20, and 30 days, after which the shear strength was tested at different times. Three sets of samples were measured for each test condition, and the average value was taken. Figure 5 As shown in (a).

[0105] Meanwhile, the above-mentioned substrate was prepared into a sample identical to wood, then coated with the adhesive of Example 6, overlapped and fixed with dovetail clips, and then placed in tap water and irradiated with 10 W ultraviolet light for 48 hours. Its UV resistance was measured by an overlap shear test. Three groups of samples were measured under each test condition, and the average value was taken. The results are shown in […]. Figure 5 (b).

[0106] The above-mentioned substrate was prepared into a sample identical to wood. The adhesive of Example 6 was then applied, overlapped, and secured with dovetail clips. The sample was cured in tap water for 1 hour, then removed and immersed in a 10% hydrogen peroxide solution for 12 hours. An overlap shear test was then performed to evaluate the antioxidant properties of the adhesive. Three groups of samples were measured under each test condition, and the average value was taken. The results are shown in [Figure Number]. Figure 5 (c).

[0107] Depend on Figure 5 As can be seen from (a)-(c), the adhesive of the present invention has excellent bonding properties to wood.

[0108] In summary, the polymer-based high-water-resistant, high-pre-compression formaldehyde-free adhesive prepared by this invention, in humid or underwater environments, allows the hydrophobic chains to repel water molecules, ensuring full contact between the adhesive and the substrate surface. Furthermore, a protective film is formed on the adhesive surface to prevent water erosion. This wood adhesive achieves instantaneous adhesion under cold pressure, exhibits strong water resistance, durability, acid and alkali resistance, and excellent temperature adaptability. It is also UV resistant and maintains effective adhesion even in strongly oxidizing solutions.

[0109] The above description is a preferred embodiment of the present invention. For those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high water-resistant, high-pre-compression formaldehyde-free wood adhesive, characterized in that, include: S1: Ethanol, water, and hydrochloric acid are added to tetraethoxysilane and dodecyltrimethoxysilane to make the pH of the system 3-4; then hydrolysis and condensation are carried out at 60-80℃ for 2-6 h to obtain the reaction product; the molar ratio of tetraethoxysilane to dodecyltrimethoxysilane is 1:0.05-0.

3. S2: The above reaction products are dried under vacuum to obtain a hydrophobic polysiloxane system; S3: Add tannic acid powder and the above-mentioned hydrophobic polysiloxane system to the polyamide polyamine epichlorohydrin solution, and stir rapidly at room temperature until a homogeneous solid gel is formed; the mass ratio of the polyamide polyamine epichlorohydrin solution, tannic acid powder and hydrophobic polysiloxane system is 5:1:0.05-0.5; the polyamide polyamine epichlorohydrin solution is a 12% aqueous solution of polyamide polyamine epichlorohydrin. S4: Place the solid gel in a centrifuge tube, centrifuge at 3000-5000 rpm for 5-10 min, then discard the supernatant to obtain a high water-resistant, high pre-compression formaldehyde-free wood adhesive.

2. The preparation method according to claim 1, characterized in that, In S1, the mass of ethanol is the same as that of tetraethoxysilane, and the amount of water used is the sum of 4 times the molar mass of tetraethoxysilane and 3 times the molar mass of dodecyltrimethoxysilane.

3. The preparation method according to claim 2, characterized in that, In step S2, the vacuum drying temperature is 30-40℃ and the time is 10-24h.

4. The preparation method according to claim 3, characterized in that, In step S3, the rapid stirring rate is 200-300 rpm; the rapid stirring time is 5 min.

5. A highly water-resistant, high-pre-compression, formaldehyde-free wood adhesive, characterized in that, Prepared by the method described in any one of claims 1-4.

6. The application of the high water-resistant, high pre-compression formaldehyde-free wood adhesive according to claim 5, characterized in that, Used for the preparation of wet wood plywood or for the repair of underwater wood structures.

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