Protein-based wood adhesive as well as preparation method and application thereof

Abstract

The invention relates to the technical field of adhesives, and provides a protein-based wood adhesive which is prepared by blending a prepolymer A and a component B with water in proportion, the prepolymer A is obtained by mixing nanocellulose, KH550 and water according to a ratio, then reacting, and then adding polyformaldehyde and a photoinitiator for further reacting; the component B is obtained by mixing nano montmorillonite, 1, 4-butanediol diglycidyl ether, polyvinyl alcohol, glacial acetic acid, maleic anhydride and soybean protein in proportion and then reacting. Polyformaldehyde with certain reaction activity is used for performing surface modification on the nano cellulose, so that the nano cellulose is subsequently subjected to cross-linking reaction with 1, 4-butanediol diglycidyl ether, acetic acid and maleic anhydride to form a multi-interpenetrating network structure form, the content of hydrophilic groups in the curing adhesive is effectively reduced, and the curing effect of the adhesive is improved. Therefore, the hydrophobicity, water resistance and mechanical strength of the adhesive can be enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and particularly to a protein-based wood adhesive. Background Art

[0002] In the prior art, traditional synthetic adhesives release formaldehyde and harmful VOCs, which are seriously harmful to the human body. Ordinary soybean protein-based adhesives have the disadvantages of poor water resistance and low mechanical strength, making it difficult to be industrially applied. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a protein-based wood adhesive and its preparation and use methods, which can significantly improve the water resistance and bonding strength of plywood.

[0004] To solve the above technical problem, the technical solution of the present invention regarding the adhesive is: a protein-based wood adhesive, which is formed by blending prepolymer A and component B with water in proportion; the prepolymer A is obtained by mixing nanocellulose, KH550 and water in proportion, reacting, and then adding paraformaldehyde and a photoinitiator for further reaction; the component B is obtained by mixing nanometer montmorillonite, 1,4-butanediol diglycidyl ether, polyvinyl alcohol, glacial acetic acid, maleic anhydride and soybean protein in proportion and then reacting.

[0005] In the above technical solution, by using paraformaldehyde with certain reaction activity to modify the surface of nanocellulose, the subsequent crosslinking reaction between nanocellulose and 1,4-butanediol diglycidyl ether, acetic acid, and maleic anhydride forms a multiple interpenetrating network structure, effectively reducing the content of hydrophilic groups in the cured adhesive, thereby enhancing the hydrophobicity, water resistance and mechanical strength of the adhesive.

[0006] Preferably, the adhesive is blended with water until uniform by mixing prepolymer A and component B in a ratio of 1:1.

[0007] Furthermore, the soybean protein is pretreated with a urea solution. Since the original protein macromolecules are in a curled state as a whole, rather than a long-chain macromolecular structure, after pretreatment, the protein macromolecules can be uncurled and unfolded, presenting a long-chain macromolecular state, and the protein macromolecules are degraded to a certain extent, and some active groups (amino, carboxyl, hydroxyl, mercapto, etc.) are fully exposed, especially the mercapto, hydroxyl, etc. on the protein long-chain molecules, so that the soybean protein can better participate in the subsequent reactions.

[0008] Preferably, by weight, the ratio of nanocellulose, KH550 to water is 0.1 - 0.2:0.1 - 0.2:0.6 - 0.7, polyoxymethylene is 10 - 15 parts, photoinitiator is 0.1 - 0.2 parts, nanometer montmorillonite is 0.5 - 2 parts, 1,4-butanediol diglycidyl ether is 5 - 15 parts, polyvinyl alcohol is 0.5 - 2 parts, glacial acetic acid is 0.8 - 1.6 parts, and maleic anhydride is 2 - 6 parts.

[0009] The present invention relates to a preparation method of the above protein-based wood adhesive, comprising the following steps: S1 Mix nanocellulose, KH550 and water in proportion and stir evenly. Under reflux conditions, heat to 50 - 60 °C and react for 2 - 3 h; then add polyoxymethylene and photoinitiator, raise the temperature to 80 - 90 °C, irradiate with ultraviolet light, react for 30 - 50 min, and quickly cool down to obtain prepolymer A.

[0010] S2 Pretreat soybean protein with urea solution; S3 Mix the pretreated soybean protein with nanometer montmorillonite, 1,4-butanediol diglycidyl ether, polyvinyl alcohol, glacial acetic acid, and maleic anhydride, stir evenly, and react for 5 - 10 min under reflux heating conditions at 60 - 80 °C to obtain component B; S4 Mix prepolymer A and component B with water in a certain proportion and stir evenly.

[0011] The protein-based wood adhesive prepared by the above technical solution can be applied to plywood.

[0012] The beneficial effects of the present invention are as follows: ① The raw materials and preparation method of the protein-based wood adhesive provided by the present invention are simple, and there is no formaldehyde and harmful VOCs release; ② After testing, the protein-based wood adhesive provided by the present invention has high mechanical strength, good water resistance, and strong versatility, and is suitable for large-scale application. Specific Embodiments

[0013] In order to make the purpose, technical solution and advantages of the invention clearer, the present invention will be described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not limited to the present invention. Example 1

[0014] A protein-based wood adhesive, which is formed by mixing prepolymer A and component B with water in proportion; the prepolymer A is obtained by reacting nanocellulose, KH550 and water in proportion, and then adding polyoxymethylene and photoinitiator for further reaction; the component B is obtained by reacting nanometer montmorillonite, 1,4-butanediol diglycidyl ether, polyvinyl alcohol, glacial acetic acid, maleic anhydride and soybean protein in proportion.

[0015] By weight, the amounts of each raw material and the preparation method are as follows: S1 Mix nanocellulose, KH550 and water in a ratio of 0.2:0.1:0.7 and stir evenly. Under reflux conditions, heat to 50 °C and react for 2 h; then add 15 parts of paraformaldehyde and 0.1 part of photoinitiator, raise the temperature to 80 °C, irradiate with ultraviolet light and stir rapidly for reaction for 30 min. After rapid cooling, centrifuge and freeze-dry to obtain modified nanocellulose prepolymer A; S2 Pretreat soy protein with 1% urea solution; S3 Blend 0.5 part of nanometer montmorillonite, 10 parts of 1,4-butanediol diglycidyl ether, 2 parts of polyvinyl alcohol, 0.5 part of glacial acetic acid, 8 parts of maleic anhydride and 20 parts of soy protein, stir evenly, and react for 5 - 10 min under the reflux heating condition of 60 - 80 °C to obtain component B; S4 Blend prepolymer A and component B with water in a ratio of 1:1, stir evenly to form an adhesive.

[0016] The usage method of the above adhesive is as follows: Quantitatively apply the adhesive to the veneer, then bond multiple veneers coated with the adhesive together and hot-press them into shape. The hot-pressing temperature is 120 - 135 °C, the hot-pressing pressure is 0.8 - 1.2 MPa, and the hot-pressing time is 180 - 300 s. Then, artificial plywood is obtained. Example 2

[0017] The raw materials and usage method of the adhesive provided in this example are the same as those in Example 1, except that the ratio of nanocellulose, KH550 and water is adjusted to 0.1:0.2:0.7, and the rest are exactly the same as those in Example 1. Example 3

[0018] The raw materials and usage method of the adhesive provided in this example are the same as those in Example 1, except that the amount of paraformaldehyde is changed to 15 parts, and the rest are exactly the same as those in Example 1. Example 4

[0019] The raw materials and usage method of the adhesive provided in this example are the same as those in Example 1, except that the amount of soy protein is changed to 15 parts, and the rest are exactly the same as those in Example 1. Example 5

[0020] The raw materials and usage method of the adhesive provided in this example are the same as those in Example 1, except that the amount of 1,4-butanediol diglycidyl ether is changed to 10 parts, and the rest are exactly the same as those in Example 1. Comparative Example 1

[0021] The adhesive provided in this comparative example does not contain KH550 in its raw materials, and the rest is the same as in Example 1. Comparative Example 2

[0022] The adhesive provided in this comparative example does not contain polyoxymethylene in its raw materials, and the rest is the same as in Example 1. Comparative Example 3

[0023] The adhesive provided in this comparative example does not contain 1,4-butanediol diglycidyl ether in its raw materials, and the rest is the same as in Example 1. Comparative Example 4

[0024] The adhesive provided in this comparative example does not contain maleic anhydride in its raw materials, and the rest is the same as in Example 1. Comparative Example 5

[0025] The adhesive provided in this comparative example does not contain soy protein in its raw materials, and the rest is the same as in Example 1.

[0026] The adhesives of Examples 1 to 5 and Comparative Examples 1 to 5 were respectively applied to plywood, and their performances were respectively tested. The test results are shown in Table 1: Table 1 Performance Test of Plywood Gluing strength (GB / T 17657-2022, dry state) / MPa Gluing strength (GB / T 17657-2022, type I boiling water treatment) / MPa Example 1 3.22 2.77 Example 2 3.14 2.54 Example 3 2.97 2.01 Example 4 2.41 1.97 Example 5 2.22 1.84 Comparative Example 1 0.75 —— Comparative Example 2 0.62 —— Comparative Example 3 0.54 —— Comparative Example 4 0.67 —— Comparative Example 5 0.21 —— It can be seen from the test results in Table 1 that the adhesives of Examples 1 to 5 are much superior to the adhesives of Comparative Examples 1 to 5 in both bonding strength and water resistance, and among them, the performance of Example 1 is the most excellent.

[0027] The above embodiments are the preferred implementation solutions of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the technical solution is within the scope of the present invention patent.

Claims

1. A protein-based wood adhesive, characterized in that: The adhesive is prepared by mixing prepolymer A and component B with water in proportion; the prepolymer A is prepared by mixing nanocellulose, KH550 and water in proportion, reacting them, and then adding polyoxymethylene and a photoinitiator for further reaction; the component B is prepared by mixing nano-montmorillonite, 1,4-butanediol diglycidyl ether, polyvinyl alcohol, glacial acetic acid, maleic anhydride and soy protein in proportion, reacting them.

2. The protein-based wood adhesive according to claim 1, characterized in that: The adhesive is prepared by mixing prepolymer A and component B with water in a ratio of 1:1 until uniform.

3. The protein-based wood adhesive according to claim 2, characterized in that: The soy protein is pretreated with a urea solution.

4. The protein-based wood adhesive according to claim 3, characterized in that: In parts by weight, the ratio of nanocellulose, KH550 and water is 0.1-0.2:0.1-0.2:0.6-0.7, polyoxymethylene is 10-15 parts, photoinitiator is 0.1-0.2 parts, nano-montmorillonite is 0.5-2 parts, 1,4-butanediol diglycidyl ether is 5-15 parts, polyvinyl alcohol is 0.5-2 parts, glacial acetic acid is 0.8-1.6 parts, and maleic anhydride is 2-6 parts.

5. A method for preparing a protein-based wood adhesive as claimed in any one of claims 1 to 4, characterized in that The following steps are involved: S1. Mix nanocellulose, KH550 and water in proportion and stir evenly. Heat to 50-60°C under reflux conditions and react for 2-3 h. Then add polyoxymethylene and photoinitiator, heat to 80-90°C, irradiate with ultraviolet light, react for 30-50 min, and quickly cool down to obtain prepolymer A. S2 pre-treated soybean protein with urea solution; S3: The pretreated soybean protein is mixed with nano-montmorillonite, 1,4-butanediol diglycidyl ether, polyvinyl alcohol, glacial acetic acid and maleic anhydride, stirred evenly, and reacted under reflux heating at 60 to 80° C. for 5 to 10 min to obtain component B; S4 Mix prepolymer A and component B with water in a certain proportion and stir evenly.

6. Use of the protein-based wood adhesive according to any one of claims 1 to 4 in artificial boards.