High-strength and high-water-retention soybean meal-based adhesive and preparation method thereof

Abstract

The invention discloses a high-strength and high-water-retention soybean meal-based adhesive and a preparation method thereof.The high-strength and high-water-retention soybean meal-based adhesive is prepared from, by weight, soybean protein meal, glucose oxidase, calcium sulfate oligomer, ethylene glycol diglycidyl ether and a dispersion medium, and the preparation method comprises the following steps that all the components are weighed according to the mass ratio; the preparation method comprises the following steps: dispersing glucose oxidase in a dispersion medium, uniformly dispersing soybean protein meal in the glucose oxidase dispersion liquid prepared in the step S1, heating for reaction, uniformly dispersing a calcium sulfate oligomer in the soybean protein meal dispersion liquid oxidized and catalyzed by the glucose oxidase prepared in the step S2, and uniformly dispersing the calcium sulfate oligomer in the soybean protein meal dispersion liquid oxidized and catalyzed by the glucose oxidase. And uniformly dispersing ethylene glycol diglycidyl ether in the dispersion liquid obtained in the step S3, and then stirring for 5 minutes. The adhesive disclosed by the invention has excellent properties in the aspects of bonding strength, water retention capacity, mildew resistance and sustainability.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, in particular to a high-strength and high-water-retention soybean meal-based adhesive and a preparation method thereof. Background Art

[0002] In recent years, adhesives have played an important role in material engineering fields such as interior decoration and machine manufacturing, but the dominance of petroleum-derived adhesives has raised concerns about potential environmental and human health risks. Plant protein meal has significant sustainable development advantages, and its innovative application in adhesives is expected to reduce environmental impact. The design of sustainable adhesives made from plant protein involves changing material properties (e.g., covalent chemical crosslinking, multiple hydrogen bonding interactions, and the number of active groups) to promote high water-resistant bonding strength and interfacial adhesion, but this usually does not give the adhesive good water retention properties.

[0003] In the application process of protein-based adhesives, water retention is the key to maintaining the stability of its mechanical properties. In practical applications, excessive water loss after glue coating will produce dry glue phenomenon, which will lead to reduced fluidity of adhesive during hot pressing and reduced bonding performance of wood-based panels after hot pressing. Therefore, how to solve the contradiction between high water-resistant bonding strength and water retention is the key to restricting the development of protein-based adhesives. Generally, the water retention of adhesives requires effective water binding capacity. In contrast, water resistance requires strong hydrophobicity after curing of adhesives. The "bond-stitch" topology structure and many hydrophilic humectants such as glycerol, sodium tripolyphosphate and zwitterions have been used to simultaneously improve the bonding strength and water retention capacity of protein-based biomass adhesives. However, the practical application of these methods is severely limited by the need for large amounts of solvents and additional polymers, resulting in reduced bonding performance. Therefore, it remains a major challenge to develop a green, simple and efficient method to prepare protein-based biomass adhesives with high bonding strength, water resistance and water retention. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] Therefore, the object of the present invention is to provide a high-strength, high-water-retention soybean meal-based adhesive and a preparation method thereof, which has excellent performance in terms of bonding strength, water-retention capacity, mildew resistance and sustainability.

[0006] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0007] A high-strength and high-water-retention soybean meal-based adhesive is modified through glucose oxidase, and comprises the following components in parts by weight: 30 parts of soybean protein meal, 0.5-5 parts of glucose oxidase, 0.5-3 parts of calcium sulfate oligomer, 0.5-2 parts of ethylene glycol diglycidyl ether and 70 parts of dispersion medium.

[0008] As a preferred embodiment of the high-strength and high-water-retention soybean meal-based adhesive described in the present invention, the soybean protein meal has a protein content of 53%, a carbohydrate content of 33%, and a particle size of the soybean protein greater than 200 meshes.

[0009] As a preferred embodiment of the high-strength and high-water-retention soybean meal-based adhesive described in the present invention, the particle size of the soybean protein is 200-250 meshes.

[0010] As a preferred embodiment of the high-strength and high-water-retention soybean meal-based adhesive described in the present invention, the dispersion medium is tap water or distilled water.

[0011] A method for preparing a high-strength and high-water-retention soybean meal-based adhesive, the specific steps are as follows:

[0012] S1. Weigh each component according to the mass ratio and disperse the glucose oxidase in the dispersion medium;

[0013] S2, uniformly dispersing soybean protein meal in the glucose oxidase dispersion prepared in step S1, and heating for reaction;

[0014] S3, uniformly dispersing the calcium sulfate oligomer in the soybean protein meal dispersion catalyzed by glucose oxidase oxidation prepared in step S2, and then stirring for 5 minutes;

[0015] S4. Ethylene glycol diglycidyl ether is uniformly dispersed in the dispersion obtained in step S3, and then stirred for 5 minutes.

[0016] As a preferred embodiment of the method for preparing a high-strength and high-water-retention soybean meal-based adhesive according to the present invention, the specific preparation steps of the calcium sulfate oligomer are as follows:

[0017] 0.22 g of CaCl2·2H2O was dissolved in 60 mL of ethanol, and then 40 mL of ethanol solution containing 0.15 g of H2SO4 (98%) and 3.04 g of TEA (99%) was mixed with rapid stirring for 2 h to obtain a translucent solution;

[0018] The solution was centrifuged at 8000 rpm for 10 min and washed with ethanol to obtain gel-like calcium sulfate oligomers.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The adhesive of the present invention uses soybean protein meal as raw material, first heats glucose oxidase with it, then mixes the reactant with calcium sulfate oligomer, and finally cross-links the soybean protein meal with ethylene glycol diglycidyl ether. Experiments have shown that the three-layer plywood manufactured by the product of the present invention does not have the problem of formaldehyde release, and the bonding strength of the plywood manufactured by the soybean protein adhesive is above 0.7MPa, with a significant strengthening effect. In addition, the bonding strength of the plywood manufactured by hot pressing after being exposed for a period of time after the glue is applied is also above 0.7MPa, with a significant water retention effect.

[0021] 2. The present invention discloses a method for preparing a protein-based biological adhesive using soybean meal, a by-product, as a main raw material, thereby increasing the added value of the by-product and avoiding the waste of resources. The present invention uses glucose oxidase to catalyze the oxidation of sugars in soybean meal, thereby generating active carboxyl groups and increasing the active sites for calcium bridge formation (glycoprotein) in calcium sulfate oligomers. The oxidation catalysis process of glucose oxidase destroys the internal electrostatic balance of soybean meal, thereby forming an acid-promoted gelling structure, reducing water evaporation and increasing interfacial adhesion, thereby solving the conflicting problem between high water-resistant bonding strength and water retention performance of protein meal adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below in combination with the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0023] Figure 1 A schematic diagram of the bonding strength of the adhesive prepared in Examples 1-2 and the comparative example provided by the present invention when coated on an adhesive single board;

[0024] Figure 2 A schematic diagram of the morphology of the adhesive cured layer observed after the adhesive prepared in Examples 1-2 and the comparative example provided by the present invention is coated on an adhesive single board;

[0025] Figure 3 A schematic diagram showing the change in appearance of an adhesive veneer over time when the adhesive prepared in Examples 1-2 and a control example provided by the present invention is applied to the adhesive veneer;

[0026] Figure 4 A schematic diagram of the pre-compression strength of the adhesive veneer coated with the adhesive prepared in Examples 1-2 and the comparative example provided by the present invention after being exposed for a certain period of time;

[0027] Figure 5A schematic diagram of the hot compression strength of an adhesive veneer coated with the adhesive prepared in Examples 1-2 and the control example provided by the present invention after being exposed for a certain period of time. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] Secondly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] The invention provides a high-strength and high-water-retention soybean meal-based adhesive and a preparation method thereof, which has excellent performance in terms of bonding strength, water-retention capacity, mildew resistance and sustainability.

[0032] The present invention provides a high-strength and high-water-retention soybean meal-based adhesive, which is modified by glucose oxidase, and includes the following components in parts by weight: 30 parts of soybean protein meal, 0.5-5 parts of glucose oxidase, 0.5-3 parts of calcium sulfate oligomer, 0.5-2 parts of ethylene glycol diglycidyl ether, and 70 parts of a dispersion medium, wherein the soybean protein meal has a protein content of 53%, a carbohydrate content of 33%, and a particle size of the soybean protein of greater than 200 meshes, and the dispersion medium is tap water or distilled water. The present invention uses the above-mentioned glucose oxidase to catalyze the oxidation of part of the carbohydrates in the soybean meal, thereby enhancing the water retention and bonding strength of the adhesive. The above-mentioned ethylene glycol diglycidyl ether can form a cross-linked network to increase the cross-linking density of the adhesive, thereby further improving the water resistance of the adhesive.

[0033] In order to verify the performance of the high-strength and high-water-retention soybean meal-based adhesive of the present invention, the following Examples 1-4 and Control Examples 1-2 are provided for comparative verification.

[0034] Example 1

[0035] S1. Dissolve 0.22 g of CaCl2·2H2O in 60 mL of ethanol, then rapidly stir and mix 40 mL of ethanol solution containing 0.15 g of H2SO4 (98%) and 3.04 g of TEA (99%) for 1 h to obtain a translucent solution. Centrifuge the solution at 8000 rpm for 10 min and wash with ethanol to obtain a gel-like calcium sulfate oligomer;

[0036] S2, dispersing 0.5 g of glucose oxidase in 35 g of distilled water;

[0037] S3, adding 15 g of soybean protein meal to the mixture obtained in step S2, and reacting at a temperature of 40° C. for 1 hour;

[0038] S4. Disperse 0.5 g of ethylene glycol diglycidyl ether uniformly in the dispersion obtained in step S3, and then stir for 5 minutes.

[0039] Example 2

[0040] S1. Dissolve 0.22 g of CaCl2·2H2O in 60 mL of ethanol, then rapidly stir and mix 40 mL of ethanol solution containing 0.15 g of H2SO4 (98%) and 3.04 g of TEA (99%) for 1 h to obtain a translucent solution. Centrifuge the solution at 8000 rpm for 10 min and wash with ethanol to obtain a gel-like calcium sulfate oligomer;

[0041] S2, dispersing 1 g of glucose oxidase in 35 g of distilled water;

[0042] S3, adding 15 g of soybean protein meal to the mixture obtained in step S2, and reacting at a temperature of 40° C. for 1 hour;

[0043] S3, adding 15 g of soybean protein meal to the mixture obtained in step S2, and reacting at a temperature of 40° C. for 1 hour;

[0044] S4. Disperse 0.5 g of ethylene glycol diglycidyl ether uniformly in the dispersion obtained in step S3, and then stir for 5 minutes.

[0045] Example 3

[0046] S1. Dissolve 0.22 g of CaCl2·2H2O in 60 mL of ethanol, then rapidly stir and mix 40 mL of ethanol solution containing 0.15 g of H2SO4 (98%) and 3.04 g of TEA (99%) for 1 h to obtain a translucent solution. Centrifuge the solution at 8000 rpm for 10 min and wash with ethanol to obtain a gel-like calcium sulfate oligomer;

[0047] S2, dispersing 1 g of glucose oxidase in 35 g of distilled water;

[0048] S3, adding 15 g of soybean protein meal to the mixture obtained in step S2, and reacting at a temperature of 40° C. for 1 hour;

[0049] S4, taking 0.5 g of the calcium sulfate oligomer prepared in step S1 and uniformly dispersing it in the dispersion obtained in step S3, and then stirring for 5 minutes;

[0050] S5. Disperse 0.5 g of ethylene glycol diglycidyl ether uniformly in the dispersion obtained in step S4, and then stir for 5 minutes.

[0051] Example 4

[0052] S1. Dissolve 0.22 g of CaCl2·2H2O in 60 mL of ethanol, then rapidly stir and mix 40 mL of ethanol solution containing 0.15 g of H2SO4 (98%) and 3.04 g of TEA (99%) for 1 h to obtain a translucent solution. Centrifuge the solution at 8000 rpm for 10 min and wash with ethanol to obtain a gel-like calcium sulfate oligomer;

[0053] S2, dispersing 1 g of glucose oxidase in 35 g of distilled water;

[0054] S3, adding 15 g of soybean protein meal to the mixture obtained in step S2, and reacting at a temperature of 40° C. for 2 hours;

[0055] S4, taking 0.75 g of the calcium sulfate oligomer prepared in step S1 and uniformly dispersing it in the dispersion obtained in step S3, and then stirring for 5 minutes;

[0056] S5. Disperse 0.5 g of ethylene glycol diglycidyl ether uniformly in the dispersion obtained in step S4, and then stir for 5 minutes.

[0057] Comparative Example 1

[0058] S1. Disperse 15 g of soybean protein meal in 35 g of distilled water;

[0059] S2. Disperse 0.5 g of ethylene glycol diglycidyl ether uniformly in the dispersion obtained in step S1, and then stir for 10 minutes.

[0060] Comparative Example 2

[0061] S1. Dissolve 0.22 g of CaCl2·2H2O in 60 mL of ethanol, then rapidly stir and mix 40 mL of ethanol solution containing 0.15 g of H2SO4 (98%) and 3.04 g of TEA (99%) for 1 h to obtain a translucent solution. Centrifuge the solution at 8000 rpm for 10 min and wash with ethanol to obtain a gel-like calcium sulfate oligomer;

[0062] S2, dispersing 1.5 g of glucose oxidase in 35 g of distilled water;

[0063] S3, adding 15 g of soybean protein meal to the mixture obtained in step S2, and reacting at a temperature of 40° C. for 1 hour;

[0064] S3, adding 15 g of soybean protein meal to the mixture obtained in step S2, and reacting at a temperature of 40° C. for 1 hour;

[0065] S4. Disperse 0.5 g of ethylene glycol diglycidyl ether uniformly in the dispersion obtained in step S3, and then stir for 5 minutes.

[0066] The performance of the modified soybean protein adhesives prepared in Control Examples 1-2 and Examples 1-4 of the present invention was tested according to the following method.

[0067] Adhesive performance evaluation experiment:

[0068] Poplar plywood, sawn according to GB / T9846.7-2004, sample size: 100mm x 25mm. Plywood preparation process parameters: glue application amount 300-400g / m 2 (double-sided), and then sent to the hot press, hot pressed at 120℃ for 360s under unit pressure of 1.0-1.2MPa. The bonding strength is tested by cooling the poplar plywood to room temperature and immersing it in warm water (60±3℃) for 3h, cooling it at room temperature for 10 minutes, and taking the average value of 6 samples in each group. The test results are as follows Figure 1-Figure 5 shown.

[0069] The experimental results show that the formaldehyde emission of the three-layer plywood made by the formaldehyde-free soy protein adhesive of the present invention is not detected, and Figure 1 As shown in the example, the bonding strength of the plywood made of the soybean protein adhesive is above 0.7 MPa. Figure 2 As shown in the figure, there are fewer holes and cracks on the surface of the cured adhesive layer, forming a uniform and dense adhesive layer, indicating that the toughness of the modified adhesive is improved. Figure 3-Figure 5 As shown in the figure, after 30 minutes of exposure to the adhesive, the bending amplitude of the veneer was significantly reduced, the pre-compression strength was tested at 0.4MPa, and the bonding strength of the plywood manufactured by hot pressing was tested at above 0.7MPa. These results all indicate that the adhesive has a good water retention effect.

[0070] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. 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, high-water-retention soybean meal-based adhesive, characterized in that: The modification is mediated by glucose oxidase, and the invention comprises the following components in parts by weight: 30 parts of soybean protein meal, 0.5-5 parts of glucose oxidase, 0.5-3 parts of calcium sulfate oligomer, 0.5-2 parts of ethylene glycol diglycidyl ether and 70 parts of dispersion medium.

2. A high-strength, high-water-retention soybean meal-based adhesive according to claim 1, characterized in that: The soybean protein meal has a protein content of 53%, a carbohydrate content of 33%, and a particle size of the soybean protein greater than 200 meshes.

3. A high-strength, high-water-retention soybean meal-based adhesive according to claim 2, characterized in that: The particle size of soy protein is 200-250 mesh.

4. A high-strength, high-water-retention soybean meal-based adhesive according to claim 1, characterized in that: The dispersion medium is tap water or distilled water.

5. A method for preparing a high-strength, high-water-retention soybean meal-based adhesive as claimed in any one of claims 1 to 4, characterized in that: The specific steps are as follows: S1. Weigh each component according to the mass ratio and disperse the glucose oxidase in the dispersion medium; S2, uniformly dispersing soybean protein meal in the glucose oxidase dispersion prepared in step S1, and heating for reaction; S3, uniformly dispersing the calcium sulfate oligomer in the soybean protein meal dispersion catalyzed by glucose oxidase oxidation prepared in step S2, and then stirring for 5 minutes; S4. Ethylene glycol diglycidyl ether is uniformly dispersed in the dispersion obtained in step S3, and then stirred for 5 minutes.

6. The method for preparing a high-strength and high-water-retention soybean meal-based adhesive according to claim 5, characterized in that: The specific preparation steps of the calcium sulfate oligomer are as follows: 0.22 g of CaCl2·2H2O was dissolved in 60 mL of ethanol, and then 40 mL of ethanol solution containing 0.15 g of H2SO4 (98%) and 3.04 g of TEA (99%) was mixed with rapid stirring for 2 h to obtain a translucent solution; The solution was centrifuged at 8000 rpm for 10 min and washed with ethanol to obtain gel-like calcium sulfate oligomers.

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