Functionalized wood fiber modified soybean protein adhesive and preparation method thereof

Abstract

The invention relates to the technical field of biomass adhesives, in particular to a functional wood fiber modified soybean protein adhesive and a preparation method thereof, and the soybean protein adhesive provided by the invention is prepared from soybean protein meal, functional wood fibers, ethylene glycol glycidyl ether and a dispersion medium. The preparation method comprises the steps of preparation of the functional wood fiber and preparation of the soybean protein adhesive. In the adhesive disclosed by the invention, the functionalized wood fiber is used as a filler to play a physical filling role and is also used as a chemical crosslinking site, so that the functionalized wood fiber and the soybean protein meal are chemically crosslinked through an epoxy ring-opening reaction of the crosslinking agent, and a more stable and compact crosslinked network is formed. The soybean protein adhesive has the advantages that the water-resistant requirement of the adhesive for the plywood can be met, and the practical performance of the soybean protein adhesive is ensured; the problem of indoor air pollution caused by common'trialdehyde 'plywood is solved; the production cost of the soybean protein adhesive is reduced, and the industrial requirements of artificial boards are met.

Description

Technical Field

[0001] The invention relates to the technical field of biomass adhesives, in particular to a functionalized wood fiber-modified soybean protein adhesive and a preparation method thereof. Background Art

[0002] Formaldehyde-based adhesives have good bonding performance and affordable prices and dominate the wood adhesive industry. However, their production relies on non-renewable fossil resources and there are problems such as formaldehyde release, which greatly limits the application and development of wood-based panels. Therefore, the development of green, environmentally friendly, high-bonding-strength and low-cost bio-based adhesives is a strong demand and inevitable trend for the development of the wood adhesive industry.

[0003] Soybean meal is a low-cost agricultural byproduct obtained after soybean oil is extracted from soybeans. Because it contains abundant active functional groups on its surface, it is considered to be an ideal choice for producing biomass-based formaldehyde-free adhesives. However, soybean meal contains a large number of hydrophilic groups, which leads to generally poor water resistance and low bonding strength of adhesives. Chemical cross-linking can effectively improve the water-resistant bonding strength of soy protein adhesives, but the use of cross-linking agents will increase the brittleness of the adhesive. Existing modification methods for strengthening and toughening soy protein adhesives still have disadvantages such as complex chemical reactions and high cost of modifier preparation, and are not enough to solve the problem of poor mildew resistance of soy protein adhesives.

[0004] Wood fiber is a multiphase polymer material composed of polymers such as cellulose, lignin and hemicellulose. Among them, cellulose has attracted extensive attention in the field of reinforced and toughened materials due to its high aspect ratio and excellent mechanical properties. However, due to the hydrophilicity of cellulose and its inherent tendency to form a strong network through hydrogen bonds, it is unevenly dispersed in the soybean meal matrix, resulting in low water stability and poor mechanical properties. Therefore, it is necessary to develop a low-cost, large-scale production strategy to solve the brittleness problem of wood fiber reinforced and toughened soybean meal adhesives, and to construct soybean protein adhesives with comprehensive properties such as high bonding strength, water resistance, and antibacterial and mildew resistance to meet the needs of practical applications. Summary of the invention

[0005] 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.

[0006] The purpose of the present invention is to provide an adhesive of functionalized wood fiber modified soybean protein and a preparation method thereof, which improves the toughness and water-resistant bonding strength of the adhesive.

[0007] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0008] A functionalized wood fiber modified soybean protein adhesive comprises, by weight, 8-15 parts of soybean protein meal, 0.5-1 part of ethylene glycol glycidyl ether, 0.5-2.5 parts of cellulose carbamate, and 35-40 parts of a dispersion medium.

[0009] As a preferred embodiment of the functionalized wood fiber modified soybean protein adhesive described in the present invention, the dispersion medium is distilled water or deionized water.

[0010] As a preferred embodiment of the functionalized wood fiber modified soybean protein adhesive described in the present invention, the mass ratio of the soybean protein meal to the cellulose carbamate is 11:2.

[0011] As a preferred embodiment of the functionalized wood fiber modified soy protein adhesive described in the present invention, the cellulose carbamate is obtained by the following method: delignifying industrial waste wood fiber biomass-wood powder, soaking the delignified product in a urea solution for swelling, dehydrating and separating, placing the delignified wood fiber-urea premix in an oven, reacting at high temperature, washing with water, and drying to obtain cellulose carbamate.

[0012] A method for preparing a functionalized wood fiber modified soybean protein adhesive, characterized in that the specific steps are as follows:

[0013] S1. Weigh each component according to the mass ratio and evenly disperse the cellulose carbamate in the dispersion medium;

[0014] S2, dispersing ethylene glycol glycidyl ether in the mixture obtained in step S1;

[0015] S3, uniformly dispersing the soybean protein meal in the dispersion of ethylene glycol glycidyl ether and cellulose carbamate obtained in step S2, and then stirring at a high speed for 10 minutes to obtain a functionalized wood fiber modified soybean protein adhesive.

[0016] As a preferred embodiment of the method for preparing a functionalized wood fiber modified soybean protein adhesive according to the present invention, in step S1, the specific preparation steps of cellulose carbamate are as follows:

[0017] Weigh 5g of sodium chlorite and 495g of distilled water to prepare a solution, weigh 5g of the required wood powder and 4mL of glacial acetic acid respectively, add them to the solution, place the solution in a heated magnetic stirrer and heat and stir at 82°C and 500-600rpm for 4h; after heating, filter with a vacuum pump to obtain the upper layer powder, wash and dry the filtered powder repeatedly to obtain delignified wood powder. Add 5g of the required delignified wood powder to a 3wt% urea solution, soak at room temperature for 1h, dehydrate and separate, place the delignified wood powder-urea premix in an oven and wash and dry at 165°C for 1h to obtain cellulose carbamate.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. Cellulose carbamate with excellent mechanical properties is used as a functional filler. It anchors and bridges cracks, thereby hindering crack propagation and significantly enhancing the strength and toughness of the adhesive layer. In addition, cellulose carbamate improves the toughness of the adhesive by interacting with hydrogen bonds between the active groups of the soy protein molecular chain and the substrate.

[0020] 2. The functionalized wood fiber prepared by the present invention has good water dispersibility and interface compatibility. By forming covalent crosslinks with soybean protein and ethylene glycol glycidyl ether, the water-resistant bonding strength of the adhesive is improved. The process is simple, green and efficient.

[0021] 3. The main raw material of the functionalized wood fiber modified soybean protein adhesive prepared by the present invention is soybean protein meal, which is inexpensive and environmentally friendly; the low-cost cellulose carbamate prepared by waste wood fiber biomass can partially replace the soybean protein meal, which further reduces the production cost of the adhesive and is conducive to making full use of agricultural and forestry waste resources and alleviating resource shortages. 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 It is a schematic diagram of wet shear strength tested on samples of the embodiments of the present invention and the comparative examples;

[0024] Figure 2 Schematic diagram of the morphology of the cured adhesive layer of the adhesive tested in this embodiment and the comparative example. DETAILED DESCRIPTION

[0025] 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 in conjunction with the accompanying drawings. It should be understood that the embodiments of the present invention are provided only for the purpose of illustration 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 the purpose and spirit of the present invention, all of which belong to the scope of the present invention.

[0026] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional operating methods. The materials, reagents, etc. used in the examples of the present invention can be purchased from the market unless otherwise specified.

[0027] In the following preferred embodiments, a functionalized wood fiber modified soybean protein adhesive comprises, by weight: 8-15 parts of soybean protein meal, 0.5-1 parts of ethylene glycol glycidyl ether, 0.5-2.5 parts of cellulose carbamate, and 35-40 parts of a dispersion medium.

[0028] Preferably, the protein content of the soybean protein meal is 53%, the carbohydrate content is 33%, the particle size of the soybean protein meal is less than 200 meshes, and the dispersion medium is distilled water or deionized water.

[0029] In order to verify the performance and effect of the functionalized wood fiber modified soybean protein adhesive of the present invention, the present invention provides the following Examples 1-3 and Comparative Examples 1-2 for testing and verification, as follows:

[0030] Example 1

[0031] S1. Weigh 5g of sodium chlorite and 495g of distilled water to prepare a solution, weigh 5g of the required wood powder and 4mL of glacial acetic acid respectively, add them to the solution, place the solution in a heated magnetic stirrer and heat and stir at 82°C and 500-600rpm for 4h; after heating, filter with a vacuum pump to obtain the upper layer of powder, wash and dry the filtered powder repeatedly to obtain delignified wood powder. Add 5g of the required delignified wood powder to a 3wt% urea solution, soak at room temperature for 1h, dehydrate and separate, place the delignified wood powder-urea premix in an oven and wash and dry at 165°C for 1h to obtain cellulose carbamate;

[0032] S2, taking 2 g of the cellulose carbamate prepared in step S1 and dispersing it in 36 g of a dispersion medium, wherein the dispersion medium used is distilled water;

[0033] S3, dispersing 0.5 g of ethylene glycol glycidyl ether in the mixture obtained in step S2,

[0034] S4. Disperse 12 g of soybean protein meal uniformly in the dispersion obtained in step S3, and then stir at high speed for 10 minutes to obtain a modified soybean protein adhesive.

[0035] Example 2

[0036] S1. Weigh 5g of sodium chlorite and 495g of distilled water to prepare a solution, weigh 5g of the required wood powder and 4mL of glacial acetic acid respectively, add them to the solution, place the solution in a heated magnetic stirrer and heat and stir at 82°C and 500-600rpm for 4h; after heating, filter with a vacuum pump to obtain the upper layer of powder, wash and dry the filtered powder repeatedly to obtain delignified wood powder. Add 5g of the required delignified wood powder to a 3wt% urea solution, soak at room temperature for 1h, dehydrate and separate, place the delignified wood powder-urea premix in an oven and wash and dry at 165°C for 1h to obtain cellulose carbamate;

[0037] S2, taking 2 g of the cellulose carbamate prepared in step S1 and dispersing it in 37 g of a dispersion medium, wherein the dispersion medium used is distilled water;

[0038] S3, dispersing 0.5 g of ethylene glycol glycidyl ether in the mixture obtained in step S2,

[0039] S4. Evenly disperse 11 g of soybean protein meal in the dispersion obtained in step S3, and then stir at high speed for 10 minutes to obtain a modified soybean protein adhesive.

[0040] Example 3

[0041] S1. Weigh 5g of sodium chlorite and 495g of distilled water to prepare a solution, weigh 5g of the required wood powder and 4mL of glacial acetic acid respectively, add them to the solution, place the solution in a heated magnetic stirrer and heat and stir at 82°C and 500-600rpm for 4h; after heating, filter with a vacuum pump to obtain the upper layer of powder, wash and dry the filtered powder repeatedly to obtain delignified wood powder. Add 5g of the required delignified wood powder to a 3wt% urea solution, soak at room temperature for 1h, dehydrate and separate, place the delignified wood powder-urea premix in an oven and wash and dry at 165°C for 1h to obtain cellulose carbamate;

[0042] S2, taking 2 g of the cellulose carbamate prepared in step S1 and dispersing it in 38 g of a dispersion medium, wherein the dispersion medium used is distilled water;

[0043] S3, dispersing 0.5 g of ethylene glycol glycidyl ether in the mixture obtained in step S2,

[0044] S4. Evenly disperse 10 g of soybean protein meal in the dispersion obtained in step S3, and then stir at high speed for 10 minutes to obtain a modified soybean protein adhesive.

[0045] Comparative Example 1

[0046] 15 g of soybean protein meal was evenly dispersed in 35 g of distilled water, and then stirred at high speed for 10 minutes.

[0047] Comparative Example 2

[0048] S1, dispersing 0.5g of ethylene glycol glycidyl ether in 35g of distilled water;

[0049] S2. Add 15 g of soybean protein meal to the mixture obtained in step S1, and then stir at high speed for 10 minutes to obtain a modified soybean protein adhesive.

[0050] This experimental example tests the performance of the modified soybean protein adhesives prepared in Examples 1-3 of the present invention and Comparative Examples 1-2:

[0051] The adhesive performance evaluation experiment uses poplar plywood, which is sawn according to GB / T9846.7-2004. The size of the sample is 100mm×25mm. The glue application area is 25mm×25mm. Plywood preparation process parameters: glue application amount 300-400g / m 2 (double-sided), and then sent to the flat vulcanizer, hot pressed at 120℃ for 330s under unit pressure of 1.0MPa. The bonding strength is tested by cooling the poplar plywood to room temperature and immersing it in 63℃ warm water for 3 hours, cooling it at room temperature for 10 minutes, and taking the average value of 6 samples in each group. The test results are shown in Table 1 and Figure 1 .

[0052] Table 1- Specimen bonding strength

[0053]

[0054]

[0055] As shown in Table 1 and Figure 1 As shown, the experimental results show that the strength of the plywood made of the soybean protein adhesive in the embodiment is above 0.7MPa, and the strength of the plywood made of the soybean protein adhesive in Example 2 is 0.98MPa. Compared with Comparative Example 1, the strengthening effect is significant.

[0056] The adhesives prepared in Examples 1-3 of the present invention and Comparative Examples 1-2 were coated on a glass sheet, cured at 120°C for 2 hours, taken out and allowed to cool to room temperature, and then photographed and recorded. The results showed that the adhesive layer formed in the examples of the present invention had a dense surface without cracks, indicating that the functional wood fiber had a significant toughening effect on the soybean protein adhesive. Figure 2 shown.

[0057] Although the present invention has been described above with reference to the embodiments, it is obvious that those skilled in the art can easily make various modifications to these embodiments based on the present invention, and apply the general principles described herein to other embodiments without creative labor. Therefore, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A functionalized wood fiber modified soybean protein adhesive, characterized in that: The invention comprises the following components in parts by weight: 8-15 parts of soybean protein meal, 0.5-1 parts of ethylene glycol glycidyl ether, 0.5-2.5 parts of cellulose carbamate and 35-40 parts of dispersion medium.

2. The functionalized wood fiber modified soybean protein 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 less than 200 meshes.

3. The functionalized wood fiber modified soybean protein adhesive according to claim 1, characterized in that: The dispersion medium is distilled water or deionized water.

4. The functionalized wood fiber modified soybean protein adhesive according to claim 1, characterized in that: The mass ratio of the soybean protein meal to the cellulose carbamate is 11:

2.

5. A method for preparing the functionalized wood fiber modified soybean protein adhesive according to 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 evenly disperse the cellulose carbamate in the dispersion medium; S2, dispersing ethylene glycol glycidyl ether in the mixture obtained in step S1; S3, uniformly dispersing the soybean protein meal in the dispersion of ethylene glycol glycidyl ether and cellulose carbamate obtained in step S2, and then stirring at a high speed for 10 minutes to obtain a functionalized wood fiber modified soybean protein adhesive.

6. The method for preparing a functionalized wood fiber modified soybean protein adhesive according to claim 5, characterized in that: In step S1, the specific preparation steps of cellulose carbamate are as follows: Weigh 5 g of sodium chlorite and 495 g of distilled water to prepare a solution, weigh 5 g of wood powder and 4 mL of glacial acetic acid, add them to the solution, place the solution in a heated magnetic stirrer and heat and stir at 82°C and 500-600 rpm for 4 hours; After heating, the upper layer powder is obtained by vacuum filtration, and the filtered powder is repeatedly washed and dried to obtain delignified wood powder. 5 g of the required delignified wood powder is added to a 3wt% urea solution, soaked at room temperature for 1 hour, dehydrated and separated, and the delignified wood powder-urea premix is ​​placed in an oven at 165°C, washed with water, and dried for 1 hour to obtain cellulose carbamate.

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