A high-strength anti-freezing plant protein adhesive based on multi-scale structure regulation and a preparation method thereof

Abstract

The application discloses a high-strength anti-freezing plant protein adhesive based on multi-scale structure regulation and a preparation method thereof. The plant protein adhesive is mainly prepared from the following raw materials: plant protein meal, anti-freezing modifier, modified cellulose nanocrystal, chemical crosslinking agent and dispersion medium. Specifically, the plant protein meal is 30 parts, the anti-freezing modifier is 10-15 parts, the modified cellulose nanocrystal is 0.5-1.2 parts, the chemical crosslinking agent is 4-6 parts and the dispersion medium is 70 parts. The application provides a high-strength anti-freezing plant protein adhesive based on multi-scale structure regulation, breaks through the low-temperature freezing and brittleness bottleneck of traditional adhesives, effectively solves the problem of poor performance of the plant protein adhesive in a low-temperature environment, fills the blank of bio-based adhesives in the low-temperature field, and has excellent performance in terms of anti-freezing performance, gluing strength, environmental protection performance and sustainability.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a high-strength, antifreeze plant protein adhesive based on multi-scale structure regulation and its preparation method. Background Technology

[0002] my country is a major producer of engineered wood products, with a volume output exceeding that of steel and plastics. However, 90% of the adhesives used in the production of engineered wood products are aldehyde resins, posing problems such as formaldehyde pollution and the non-renewable nature of the raw materials. Plant protein adhesives, as a green and environmentally friendly biomass adhesive, have broad application prospects in fields such as wood processing due to their advantages of wide availability of raw materials, low price, renewability, and no pollution.

[0003] Therefore, developing high-quality plant protein adhesives to address formaldehyde pollution in human living environments at its source is of great significance for achieving sustainable development of the engineered wood products industry, protecting public health, and serving national strategies. However, traditional plant protein adhesives have some drawbacks that limit their application in certain special environments. In low-temperature environments, the performance of ordinary plant protein adhesives deteriorates significantly, such as reduced bonding strength, decreased flexibility, and even brittleness. This is mainly because the water in plant protein molecules freezes, and the formation of ice crystals disrupts the interactions between protein molecules and the microstructure of the adhesive. Currently, research on the low-temperature resistance of plant protein adhesives is relatively limited, and existing improvement methods have limited effectiveness and cannot meet the practical needs of use in cold regions or under low-temperature conditions. Therefore, developing a plant protein adhesive with good antifreeze properties has significant practical significance and market demand. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] Based on existing research, the purpose of this invention is to provide a high-strength, freeze-resistant plant protein adhesive based on multi-scale structural regulation. This adhesive can effectively solve the problem of poor performance of plant protein adhesives in low-temperature environments, fill the gap in the low-temperature field of bio-based adhesives, and has excellent performance in terms of freeze resistance, bonding strength, environmental performance, and sustainability.

[0006] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0007] A high-strength antifreeze plant protein adhesive based on multi-scale structure regulation comprises the following components in parts by weight: 30 parts plant protein meal, 10-15 parts antifreeze modifier, 0.5-1.2 parts modified cellulose nanocrystals, 4-6 parts chemical crosslinking agent, and 70 parts dispersion medium.

[0008] As a preferred embodiment of the high-strength antifreeze plant protein adhesive based on multi-scale structure regulation described in this invention, the plant protein meal contains 53% protein, 33% carbohydrates, and the particle size of the plant protein is greater than 200 mesh.

[0009] As a preferred embodiment of the high-strength antifreeze plant protein adhesive based on multi-scale structure regulation described in this invention, the particle size of the plant protein is 200-250 mesh.

[0010] As a preferred embodiment of the high-strength antifreeze plant protein adhesive based on multi-scale structure regulation described in this invention, the chemical crosslinking agent is one or more of ethylene glycol glycidyl ether, glycidylamine epoxy resin, or glycerol glycidyl ether.

[0011] As a preferred embodiment of the high-strength antifreeze plant protein adhesive based on multi-scale structure regulation described in this invention, the dispersion medium is tap water or distilled water.

[0012] A method for preparing a high-strength, freeze-resistant plant protein adhesive based on multi-scale structural regulation, comprising the following steps:

[0013] S1. Weigh each component according to the mass ratio, disperse the plant protein meal in the dispersion medium, and stir at 20°C until the dispersion is uniform to obtain soybean meal dispersion.

[0014] S2. Disperse the antifreeze modifier and modified cellulose nanocrystals evenly in the soybean meal dispersion prepared in step S1, and stir at 60°C for 0.5 hours.

[0015] S3. Disperse the chemical crosslinking agent evenly into the solution obtained in step S2, and stir evenly to obtain a high-strength antifreeze plant protein adhesive based on multi-scale structure regulation.

[0016] As a preferred embodiment of the preparation method of the high-strength antifreeze plant protein adhesive based on multi-scale structure regulation according to the present invention, the specific preparation steps of the antifreeze modifier are as follows:

[0017] Add 3.0 mL of acrylic acid, 1.0 g of N-ethylacrylamide and 45.0 mg of guar gum to 3.0 mL of ammonium persulfate solution (6.6 mg / mL) and stir until homogeneous.

[0018] Add 0.7g of antifreeze protein to the above solution, stir for 10 minutes, then add 12.0mg of FeCl3 and stir continuously until homogeneous to obtain the antifreeze modifier.

[0019] As a preferred embodiment of the preparation method of the high-strength antifreeze plant protein adhesive based on multi-scale structure regulation according to the present invention, the specific preparation steps of the modified cellulose nanocrystals are as follows:

[0020] 100.0 mg of cellulose nanocrystals were dissolved in deionized water, and the pH was adjusted to 8.5 by adding Tris-HCl buffer solution. 100.0 mg of dopamine powder was added and stirred continuously. The mixture was centrifuged and washed four times until it turned into a dark gray appearance, thus obtaining CNCs@PDA.

[0021] 0.09 g of zwitterionic proline was added to 5.0 mL of 0.36 wt% CNCs@PDA and stirred at 400 rpm for 10 h at 25 °C. After centrifugation, washing, and drying, modified cellulose nanocrystals were obtained.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The adhesive of this invention uses plant protein meal as raw material. The plant protein meal is blended with an antifreeze modifier and modified cellulose nanocrystals, and finally crosslinked with chemical crosslinking agents such as glycidyl amine epoxy resin. Experiments have shown that the three-layer plywood manufactured using this invention does not have formaldehyde release issues. The wet bonding strength of plywood manufactured with the plant protein adhesive is above 0.7 MPa, and the dry bonding strength is generally above 1.80 MPa, demonstrating a significant strengthening effect.

[0024] 2. Antifreeze protein is a protein that can inhibit ice crystal growth and lower the freezing point. Based on the mussel-inspired chemistry principle, dopamine is introduced to increase adhesion and chemical cross-linking points. Zwitterionic proline is modified onto the surface of cellulose nanocrystals. While enhancing the adhesive properties of plant protein adhesives, the synergistic effect with antifreeze modifiers further regulates the mechanical and antifreeze properties of plant protein adhesives. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0026] Figure 1Schematic diagram of the adhesive strength tested when the adhesives prepared in Examples 1-4 and Comparative Examples 1-3 of this invention were coated on adhesive veneers;

[0027] Figure 2 The shear strength diagrams of the adhesives prepared in Examples 1-4 and Comparative Examples 1-3 of this invention after being treated at different freezing temperatures (-10℃, -20℃, -30℃) are shown.

[0028] Figure 3 The diagram shows the retention rate of shear strength relative to room temperature after the adhesives prepared in Examples 1-4 and Comparative Examples 1-3 of this invention have been treated at different freezing temperatures (-10℃, -20℃, -30℃). Detailed Implementation

[0029] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the embodiments of the present invention are given for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and intent, and all such modifications and substitutions fall within the scope of the present invention.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0031] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional operating methods. Unless otherwise specified, the materials and reagents used in the embodiments of this invention can be purchased commercially.

[0032] Unless otherwise specified, the term "parts" in this invention refers to parts by weight.

[0033] This invention provides a high-strength, freeze-resistant plant protein adhesive based on multi-scale structural regulation, which effectively solves the problem of poor performance of plant protein adhesives in low-temperature environments, fills the gap in low-temperature fields of bio-based adhesives, and has excellent performance in terms of freeze resistance, bonding strength, environmental performance and sustainability.

[0034] This high-strength, antifreeze plant protein adhesive based on multi-scale structure regulation comprises the following components by weight: 30 parts plant protein meal, 10-15 parts antifreeze modifier, 0.5-1.2 parts modified cellulose nanocrystals, 4-6 parts chemical crosslinking agent, and 70 parts dispersion medium. The plant protein meal contains 53% protein and 33% carbohydrates, with a particle size greater than 200 mesh. The chemical crosslinking agent is one or more of ethylene glycol glycidyl ether, glycidylamine epoxy resin, or glycerol glycidyl ether. The dispersion medium is tap water or distilled water.

[0035] To verify the performance of the high-strength antifreeze plant protein adhesive based on multi-scale structure regulation of the present invention, the following Examples 1-4 and Comparative Examples 1-3 are provided for comparison and verification.

[0036] Example 1

[0037] S1. Dissolve 100.0 mg of cellulose nanocrystals in deionized water, adjust the pH to 8.5 with Tris-HCl buffer solution, add 100.0 mg of dopamine powder and stir continuously. The mixture is centrifuged and washed four times until it turns dark gray, yielding CNCs@PDA. Add 0.09 g of zwitterionic proline to 5.0 mL of 0.36 wt% CNCs@PDA, stir at 400 rpm for 10 h at 25 °C, and then centrifuge, wash, and dry to obtain modified cellulose nanocrystals.

[0038] S2. Disperse 30g of plant protein meal in 70g of dispersion medium and stir at 20℃ until the dispersion is uniform to obtain soybean meal dispersion.

[0039] S3. Disperse 10g of antifreeze modifier and 0.5g of modified cellulose nanocrystals prepared in step S1 evenly in the soybean meal dispersion prepared in step S2, and stir at 60°C for 0.5 hours.

[0040] S4. Disperse 4g of chemical crosslinking agent evenly into the dispersion obtained in step S3, and then stir for 5 minutes.

[0041] Example 2

[0042] S1. Dissolve 100.0 mg of cellulose nanocrystals in deionized water, adjust the pH to 8.5 with Tris-HCl buffer solution, add 100.0 mg of dopamine powder and stir continuously. The mixture is centrifuged and washed four times until it turns dark gray, yielding CNCs@PDA. Add 0.09 g of zwitterionic proline to 5.0 mL of 0.36 wt% CNCs@PDA, stir at 400 rpm for 10 h at 25 °C, and then centrifuge, wash, and dry to obtain modified cellulose nanocrystals.

[0043] S2. Disperse 30g of plant protein meal in 70g of dispersion medium and stir at 20℃ until the dispersion is uniform to obtain soybean meal dispersion.

[0044] S3. Disperse 15g of antifreeze modifier and 0.5g of modified cellulose nanocrystals prepared in step S1 evenly in the soybean meal dispersion prepared in step S2, and stir at 60°C for 0.5 hours.

[0045] S4. Disperse 4g of chemical crosslinking agent evenly into the dispersion obtained in step S3, and then stir for 5 minutes.

[0046] Example 3

[0047] S1. Dissolve 100.0 mg of cellulose nanocrystals in deionized water, adjust the pH to 8.5 with Tris-HCl buffer solution, add 100.0 mg of dopamine powder and stir continuously. The mixture is centrifuged and washed four times until it turns dark gray, yielding CNCs@PDA. Add 0.09 g of zwitterionic proline to 5.0 mL of 0.36 wt% CNCs@PDA, stir at 400 rpm for 10 h at 25 °C, and then centrifuge, wash, and dry to obtain modified cellulose nanocrystals.

[0048] S2. Disperse 30g of plant protein meal in 70g of dispersion medium and stir at 20℃ until the dispersion is uniform to obtain soybean meal dispersion.

[0049] S3. Disperse 10g of antifreeze modifier and 1.0g of modified cellulose nanocrystals prepared in step S1 evenly in the soybean meal dispersion prepared in step S2, and stir at 60°C for 0.5 hours.

[0050] S4. Disperse 4g of chemical crosslinking agent evenly into the dispersion obtained in step S3, and then stir for 5 minutes.

[0051] Example 4

[0052] S1. Dissolve 100.0 mg of cellulose nanocrystals in deionized water, adjust the pH to 8.5 with Tris-HCl buffer solution, add 100.0 mg of dopamine powder and stir continuously. The mixture is centrifuged and washed four times until it turns dark gray, yielding CNCs@PDA. Add 0.09 g of zwitterionic proline to 5.0 mL of 0.36 wt% CNCs@PDA, stir at 400 rpm for 10 h at 25 °C, and then centrifuge, wash, and dry to obtain modified cellulose nanocrystals.

[0053] S2. Disperse 30g of plant protein meal in 70g of dispersion medium and stir at 20℃ until the dispersion is uniform to obtain soybean meal dispersion.

[0054] S3. Disperse 15g of antifreeze modifier and 1.0g of modified cellulose nanocrystals prepared in step S1 evenly in the soybean meal dispersion prepared in step S2, and stir at 60°C for 0.5 hours.

[0055] S4. Disperse 4g of chemical crosslinking agent evenly into the dispersion obtained in step S3, and then stir for 5 minutes.

[0056] Comparative Example 1

[0057] S1. Disperse 30g of plant protein meal in 70g of dispersion medium and stir at 20℃ until the dispersion is uniform to obtain soybean meal dispersion.

[0058] S2. Disperse 4g of chemical crosslinking agent evenly into the dispersion obtained in step S1, and then stir for 10 minutes.

[0059] Comparative Example 2

[0060] S1. Dissolve 100.0 mg of cellulose nanocrystals in deionized water, adjust the pH to 8.5 with Tris-HCl buffer solution, add 100.0 mg of dopamine powder and stir continuously. The mixture is centrifuged and washed four times until it turns dark gray, yielding CNCs@PDA. Add 0.09 g of zwitterionic proline to 5.0 mL of 0.36 wt% CNCs@PDA, stir at 400 rpm for 10 h at 25 °C, and then centrifuge, wash, and dry to obtain modified cellulose nanocrystals.

[0061] S2. Disperse 30g of plant protein meal in 70g of dispersion medium and stir at 20℃ until the dispersion is uniform to obtain soybean meal dispersion.

[0062] S3. Disperse 10g of antifreeze modifier evenly in the soybean meal dispersion prepared in step S2, and stir at 60℃ for 0.5 hours;

[0063] S4. Disperse 4g of chemical crosslinking agent evenly into the dispersion obtained in step S3, and then stir for 5 minutes.

[0064] Comparative Example 3

[0065] S1. Dissolve 100.0 mg of cellulose nanocrystals in deionized water, adjust the pH to 8.5 with Tris-HCl buffer solution, add 100.0 mg of dopamine powder and stir continuously. The mixture is centrifuged and washed four times until it turns dark gray, yielding CNCs@PDA. Add 0.09 g of zwitterionic proline to 5.0 mL of 0.36 wt% CNCs@PDA, stir at 400 rpm for 10 h at 25 °C, and then centrifuge, wash, and dry to obtain modified cellulose nanocrystals.

[0066] S2. Disperse 30g of plant protein meal in 70g of dispersion medium and stir at 20℃ until the dispersion is uniform to obtain soybean meal dispersion.

[0067] S3. Disperse 1.0g of the modified cellulose nanocrystals prepared in step S1 evenly in the soybean meal dispersion prepared in step S2, and stir at 60°C for 0.5 hours.

[0068] S4. Disperse 4g of chemical crosslinking agent evenly into the dispersion obtained in step S3, and then stir for 5 minutes.

[0069] The modified plant protein adhesives prepared in Comparative Examples 1-3 and Examples 1-4 of the present invention were subjected to performance tests according to the following methods.

[0070] Adhesive performance evaluation experiment:

[0071] Poplar plywood, sawn according to GB / T9846.7-2004, sample size: 100mm × 25mm. Plywood preparation process parameters: glue application rate 300-400g / m². 2 (Double-sided) Then, it is sent to a hot press and hot-pressed at 120℃ for 360s under a unit pressure of 1.0-1.2MPa. The bond strength is tested by immersing the poplar plywood in warm water (60±3℃) for 3 hours after cooling to room temperature, followed by cooling at room temperature for 10 minutes. The average value of 6 samples in each group is taken. The test results are as follows... Figure 1 As shown.

[0072] Poplar plywood, sawn according to GB / T9846.7-2004, sample size: 100mm × 25mm. Plywood preparation process parameters: glue application rate 300-400g / m². 2 (Double-sided) The specimens are then placed in a hot press and hot-pressed at 120℃ for 360 seconds under a unit pressure of 1.0-1.2 MPa. Six specimens are placed in a low-temperature freezer at different freezing temperatures (-10℃, -20℃, -30℃) for 24 hours. The frozen specimens are then removed and thawed at room temperature for 2 hours. Their shear strength is then tested on a mechanical testing machine at a tensile test speed of 10.0 mm / min.

[0073] Calculate the retention rate of shear strength at different freezing temperatures relative to the room temperature control group:

[0074] Retention rate (%) = (X) n / X0)×100%, where X n X represents the shear strength at different freezing temperatures, with X0 representing the shear strength of the room temperature control group. The freeze-thaw resistance of plant protein wood adhesives was evaluated by analyzing the retention rate; a higher retention rate indicates better freeze-thaw resistance.

[0075] Experimental results show that the formaldehyde release of the three-layer plywood manufactured with the formaldehyde-free plant protein adhesive of the present invention was undetectable, and Figure 1 As shown, the wet bond strength of the plywood made with the plant protein adhesive in the examples is above 0.70 MPa, and the dry bond strength is basically above 1.80 MPa. Figure 2 and Figure 3 As shown, the plant protein adhesive with added antifreeze modifier and modified cellulose nanocrystals can still retain more than 62% of its shear strength at -30℃, which indicates that the adhesive has good antifreeze properties.

[0076] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A high-strength, antifreeze plant protein adhesive based on multi-scale structural regulation, characterized in that, include: Plant protein meal, antifreeze modifier, modified cellulose nanocrystals, chemical crosslinking agent, dispersion medium; The composition, by weight, includes 30 parts of plant protein meal, 10-15 parts of antifreeze modifier, 0.5-1.2 parts of modified cellulose nanocrystals, 4-6 parts of chemical crosslinking agent, and 70 parts of dispersion medium. The specific preparation steps of the antifreeze modifier are as follows: S1. Add 3.0 mL of acrylic acid, 1.0 g of N-ethylacrylamide and 45.0 mg of guar gum to 3.0 mL of 6.6 mg / mL ammonium persulfate solution and stir until homogeneous; S2. Add 0.7g of antifreeze protein to the above solution, stir for 10min, then add 12.0mg of FeCl3 and stir continuously until homogeneous to obtain the antifreeze modifier. The specific preparation steps for the modified cellulose nanocrystals are as follows: S1. Dissolve 100.0 mg of cellulose nanocrystals in deionized water, add Tris-HCl buffer solution to adjust the pH to 8.5, add 100.0 mg of dopamine powder and stir continuously. The mixture is centrifuged and washed four times until it turns into a dark gray appearance, thus obtaining CNCs@PDA. S2. Add 0.09 g of zwitterionic proline to 5.0 mL of 0.36 wt% CNCs@PDA, stir at 400 rpm for 10 h at 25 °C, and obtain modified cellulose nanocrystals by centrifugation, washing and drying. The chemical crosslinking agent is one or more of ethylene glycol glycidyl ether, glycidylamine epoxy resin, or glycerol glycidyl ether.

2. The high-strength, antifreeze plant protein adhesive based on multi-scale structure regulation according to claim 1, characterized in that, The plant protein meal contains 53% protein and 33% carbohydrates, and the plant protein has a particle size greater than 200 mesh.

3. The high-strength, antifreeze plant protein adhesive based on multi-scale structure regulation according to claim 1, characterized in that, The dispersion medium is tap water or distilled water.

4. A method for preparing a high-strength, antifreeze plant protein adhesive based on multi-scale structure regulation as described in any one of claims 1-3, characterized in that, The specific steps are as follows: S1. Weigh each component according to the mass ratio, disperse the plant protein meal in the dispersion medium, and stir at 20°C until the dispersion is uniform to obtain soybean meal dispersion. S2. Disperse the antifreeze modifier and modified cellulose nanocrystals evenly in the soybean meal dispersion prepared in step S1, and stir at 60°C for 0.5 hours. S3. Disperse the chemical crosslinking agent evenly into the solution obtained in step S2, and stir evenly to obtain a high-strength antifreeze plant protein adhesive based on multi-scale structure regulation.

5. The application of a high-strength, frost-resistant plant protein adhesive based on multi-scale structure regulation as described in any one of claims 1-3 in wood processing and frost-resistant and cold-resistant engineered wood products.

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