Sustainable waterproof mildew-proof soybean protein adhesive and preparation method thereof

Abstract

The invention relates to a sustainable waterproof mildew-proof soybean protein adhesive and a preparation method thereof, and belongs to the technical field of soybean protein adhesives. The sustainable waterproof mildew-proof soybean protein adhesive is prepared from the following raw materials in parts by mass: 15 to 35 parts of soybean meal, 55 to 75 parts of water, 2 to 6 parts of cross-linking agent, 0.1 to 0.5 part of sodium carboxymethyl cellulose and 0.5 to 2 parts of ethyl lauroyl arginate hydrochloride. According to the invention, sodium carboxymethyl cellulose, ethyl lauroyl arginate hydrochloride and a cross-linking agent are introduced into a soybean meal system, so that the sustainable water-resistant mildew-proof soybean protein adhesive is prepared. The lauroyl arginine ethyl ester hydrochloride, the soybean meal and the sodium carboxymethyl cellulose respectively form high-specificity guanidyl carboxylate bridge hydrogen bonds, so that a heterogeneous structure is formed in a system, internal energy dissipation is improved, and the toughness and the water resistance of the adhesive are further improved. Meanwhile, due to the broad-spectrum antibacterial property of the ethyl lauroyl arginate hydrochloride, the adhesive has better corrosion-resistant and antibacterial effects.

Description

Technical Field

[0001] The invention relates to a sustainable water-resistant and mildew-proof soybean protein adhesive and a preparation method thereof, belonging to the technical field of soybean protein adhesives. Background Art

[0002] With the enhancement of people's environmental awareness and the improvement of laws and regulations, traditional adhesives are mostly derived from non-renewable resources such as petroleum-based adhesives. During the production and use process, they will aggravate the shortage of petroleum resources and the deterioration of the environment. The toxic gases released seriously endanger people's health and are difficult to meet actual needs. Therefore, it is urgent to develop green and environmentally friendly bio-based adhesives to replace traditional petroleum-based adhesives.

[0003] As a by-product of soybean processing, soybean meal has the advantages of a wide range of raw material sources, easy processing, and biodegradability, and has received widespread attention from the wood-based panel industry. However, pure protein adhesives have poor water resistance and are susceptible to microbial erosion, which limits their further development. Chemical modification is considered to be the most effective method to improve the performance of soybean protein adhesives. The introduction of substances such as sodium dodecyl sulfate, polyamide epichlorohydrin, polyurethane, and acrylic acid can greatly improve the performance of soybean protein adhesives and avoid the release of formaldehyde gas to a certain extent. However, the above substances will have a certain impact on the environment during production or emission, and are not completely green and environmentally friendly.

[0004] Therefore, there is an urgent need to find greener and more environmentally friendly methods to improve the water resistance and mildew resistance of adhesives in order to promote the large-scale industrial production of soy protein adhesives as soon as possible. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a sustainable water-resistant and mildew-proof soybean protein adhesive and a preparation method thereof.

[0006] The technical solution of the present invention is as follows:

[0007] A sustainable water-resistant and mildew-proof soybean protein adhesive is composed of the following raw materials in parts by weight: 15 to 35 parts of soybean meal, 55 to 75 parts of water, 2 to 6 parts of a cross-linking agent, 0.1 to 0.5 parts of sodium carboxymethyl cellulose, and 0.5 to 2 parts of ethyl lauroyl arginine hydrochloride.

[0008] Preferably according to the present invention, the soybean meal has a soybean protein content of 45-50% and a fineness of 75-85 meshes.

[0009] Preferably according to the present invention, the cross-linking agent is triglycidylamine or ethylene glycol diglycidyl ether.

[0010] Preferably according to the present invention, the mass of the cross-linking agent is 2-6% of the sum of the mass of soybean meal and water.

[0011] Preferably according to the present invention, the mass of the sodium carboxymethyl cellulose is 0.1-0.2% of the sum of the mass of soybean meal and water.

[0012] Preferably according to the present invention, the mass of lauroyl arginine ethyl ester hydrochloride is 0.5-2% of the sum of the mass of soybean meal and water.

[0013] Preferably, according to the present invention, the sustainable water-resistant and mildew-proof soybean protein adhesive is composed of the following raw materials in parts by mass: 28 parts of soybean meal, 72 parts of water, 4 parts of a cross-linking agent, 0.15 parts of sodium carboxymethyl cellulose, and 1 part of ethyl lauroyl arginine hydrochloride;

[0014] The mass of the cross-linking agent is 4% of the sum of the mass of soybean meal and water, the mass of the lauroyl arginine ethyl ester hydrochloride is 1% of the sum of the mass of soybean meal and water, and the mass of the sodium carboxymethyl cellulose is 0.15% of the sum of the mass of soybean meal and water.

[0015] The method for preparing the above-mentioned sustainable water-resistant and mildew-proof soybean protein adhesive comprises the following steps:

[0016] (1) dissolving sodium carboxymethyl cellulose and lauroyl arginine ethyl ester hydrochloride in water according to a ratio, stirring and mixing, and obtaining a composite solution of sodium carboxymethyl cellulose and lauroyl arginine ethyl ester hydrochloride;

[0017] (2) adding soybean meal and a cross-linking agent into the composite solution of sodium carboxymethyl cellulose and ethyl lauroyl arginine hydrochloride obtained in step (1) according to a ratio, and mechanically stirring the mixture to obtain a sustainable water-resistant and mildew-resistant soybean protein adhesive.

[0018] The above sustainable water-resistant and mildew-resistant soy protein adhesive is used in wood processing and artificial boards.

[0019] In the present invention, "%" not specifically stated refers to mass percentage.

[0020] The technical features and beneficial effects of the present invention are as follows:

[0021] 1. The present invention introduces sodium carboxymethyl cellulose, lauroyl arginine ethyl ester hydrochloride and a cross-linking agent into a soybean meal system, ingeniously utilizes the difference in electrical properties of bio-based materials, and prepares a sustainable water-resistant and mildew-proof soybean protein adhesive through multiple effects such as electrostatic adsorption, salt bridge hydrogen bonding and covalent bonding. Among them, lauroyl arginine ethyl ester hydrochloride can attract the negatively charged sodium carboxymethyl cellulose through electrostatic action, and at the same time, the guanidine group in its structure forms salt bridge hydrogen bonding with the active groups on soybean meal and sodium carboxymethyl cellulose, respectively, to produce a non-uniform hierarchical structure, improve the network interweaving density and energy dissipation of the entire system, thereby improving the bonding strength. In addition, the present invention further improves the water resistance of the adhesive by using a cross-linking agent to form a covalent bond by a ring-opening reaction with soybean meal.

[0022] 2. The main raw materials of the present invention, soybean meal, sodium carboxymethyl cellulose and lauroyl arginine ethyl ester hydrochloride, are all bio-based materials or their derivatives, which are green, environmentally friendly and biodegradable, and conform to the concept of green sustainable development. In addition, lauroyl arginine ethyl ester hydrochloride, as a cationic surfactant, can change the permeability of cell membranes, has a significant inhibitory effect on microorganisms such as bacteria, yeast, and mold, and has a good antiseptic and antibacterial effect.

[0023] 3. The sustainable water-resistant and mildew-proof soybean protein adhesive of the present invention has simple process, is non-toxic and harmless, and has stable performance. It can be applied to wood processing and artificial boards, and the plywood produced meets the national requirements for Class II plywood. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a graph showing the anti-corrosion test results in the test example.

[0025] Figure 2 This is a graph showing the antibacterial test results in the test example. DETAILED DESCRIPTION

[0026] The technical scheme of the present invention is further described by the following examples. It should be noted that the following examples are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0027] The soybean meal used in the following examples has a soybean protein content of 47% and a fineness of 80 meshes, and is purchased from Shandong Yuwang Group.

[0028] Ethylene glycol diglycidyl ether, sodium carboxymethyl cellulose, and lauroyl arginine ethyl ester hydrochloride were purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0029] The crosslinking agent triglycidylamine described in the examples was prepared according to the method reported in the published document “Triglycidylamine crosslinking of porcine aortic valve cusps or bovine pericardium results in improved biocompatibility, biomechanics, and calcification resistance: chemical and biological mechanisms”.

[0030] Example 1

[0031] A sustainable water-resistant and mildew-proof soybean protein adhesive is composed of the following raw materials in parts by mass: 28 g soybean meal, 72 g water, 2 g triglycidylamine, 0.15 g sodium carboxymethyl cellulose, and 0.5 g lauroyl arginine ethyl ester hydrochloride.

[0032] The specific preparation method of the above sustainable water-resistant and mildew-proof soybean protein adhesive is as follows:

[0033] (1) dissolving sodium carboxymethyl cellulose and lauroyl arginine ethyl ester hydrochloride in water according to a ratio, stirring and mixing, and obtaining a composite solution of sodium carboxymethyl cellulose and lauroyl arginine ethyl ester hydrochloride;

[0034] (2) adding soybean meal and triglycidylamine to the composite solution of sodium carboxymethyl cellulose and lauroyl arginine ethyl ester hydrochloride obtained in step (1) according to the ratio, and mechanically stirring the mixture to obtain a sustainable water-resistant and mildew-proof soybean protein adhesive.

[0035] Example 2

[0036] A sustainable water-resistant and mildew-proof soybean protein adhesive is composed of the following raw materials in parts by mass: 28 g soybean meal, 72 g water, 2 g ethylene glycol diglycidyl ether, 0.15 g sodium carboxymethyl cellulose, and 0.5 g lauroyl arginine ethyl ester hydrochloride.

[0037] The preparation method of the sustainable water-resistant and mildew-proof soybean protein adhesive in this embodiment is consistent with that in Example 1.

[0038] Example 3

[0039] A sustainable water-resistant and mildew-proof soybean protein adhesive is composed of the following raw materials in parts by weight: 28 g soybean meal, 72 g water, 4 g triglycidylamine, 0.15 g sodium carboxymethyl cellulose, and 0.5 g lauroyl arginine ethyl ester hydrochloride.

[0040] The preparation method of the sustainable water-resistant and mildew-proof soybean protein adhesive in this embodiment is consistent with that in Example 1.

[0041] Example 4

[0042] A sustainable water-resistant and mildew-proof soybean protein adhesive is composed of the following raw materials in parts by weight: 28 g soybean meal, 72 g water, 6 g triglycidylamine, 0.15 g sodium carboxymethyl cellulose, and 0.5 g lauroyl arginine ethyl ester hydrochloride.

[0043] The preparation method of the sustainable water-resistant and mildew-proof soybean protein adhesive in this embodiment is consistent with that in Example 1.

[0044] Example 5

[0045] A sustainable water-resistant and mildew-proof soybean protein adhesive is composed of the following raw materials in parts by weight: 28 g soybean meal, 72 g water, 4 g triglycidylamine, 0.15 g sodium carboxymethyl cellulose, and 1 g lauroyl arginine ethyl ester hydrochloride.

[0046] The preparation method of the sustainable water-resistant and mildew-proof soybean protein adhesive in this embodiment is consistent with that in Example 1.

[0047] Example 6

[0048] A sustainable water-resistant and mildew-proof soybean protein adhesive is composed of the following raw materials in parts by weight: 28 g soybean meal, 72 g water, 4 g triglycidylamine, 0.15 g sodium carboxymethyl cellulose, and 2 g lauroyl arginine ethyl ester hydrochloride.

[0049] The preparation method of the sustainable water-resistant and mildew-proof soybean protein adhesive in this embodiment is consistent with that in Example 1.

[0050] Comparative Example 1

[0051] A soybean protein adhesive is composed of the following raw materials in parts by weight: 28 g soybean meal and 72 g water.

[0052] The soybean protein adhesive in this comparative example is prepared according to the following method: soybean meal is added into water according to a ratio, and mechanically stirred to obtain the soybean protein adhesive.

[0053] Comparative Example 2

[0054] A soybean protein adhesive is composed of the following raw materials in parts by mass: 28 g soybean meal, 72 g water, and 4 g triglycidylamine.

[0055] The soybean protein adhesive in this comparative example is prepared according to the following method: soybean meal and triglycidylamine are added into water according to a ratio, and mechanically stirred to obtain the soybean protein adhesive.

[0056] Comparative Example 3

[0057] A soybean protein adhesive is composed of the following raw materials in parts by weight: 28 g soybean meal, 72 g water, 4 g triglycidylamine, and 0.15 g sodium carboxymethyl cellulose.

[0058] The soy protein adhesive described in this comparative example is prepared according to the following method: sodium carboxymethyl cellulose is dissolved in water according to a ratio to obtain a sodium carboxymethyl cellulose aqueous solution; then soybean meal and triglycidylamine are added to the sodium carboxymethyl cellulose aqueous solution, and mechanical stirring is performed to obtain a soy protein adhesive.

[0059] Test example

[0060] 1. Three-layer plywood was prepared using the soybean protein adhesives prepared in Examples 1 to 6 of the present invention and Comparative Examples 1 to 3 respectively.

[0061] Single board size: 200mm×100mm×2mm

[0062] According to the following normal preparation process:

[0063] Gluing: single-sided gluing, glue coating amount is 180~200g / m 2 .

[0064] Hot pressing: pressure 1 MPa, temperature 120°C, time 6 min.

[0065] After the hot pressing, the prepared plywood was placed at room temperature for 24 hours and then cut into 100mm×25mm×2mm specimens using a cutting machine. The product was tested for performance according to the test method of GB / T17657-2013 “Test methods for physical and chemical properties of wood-based panels and veneered wood-based panels”. The test results are shown in Table 1.

[0066] Table 1. Bonding properties of soybean protein adhesive

[0067] Test piece Wet shear strength / MPa Example 1 0.92 Example 2 0.90 Example 3 0.98 Example 4 0.95 Example 5 1.07 Example 6 1.02 Comparative Example 1 0.47 Comparative Example 2 0.80 Comparative Example 3 0.85

[0068] As can be seen from Table 1, the wet shear strength of the adhesives prepared in Examples 1 to 6 is greater than 0.7MPa, meeting the national strength requirements for Class II plywood. Among them, according to the results of the comparative example, the wet shear strength of the pure soybean meal adhesive is relatively low, only 0.47MPa. The cross-linking agent forms covalent crosslinks by a ring-opening reaction with soybean meal, thereby improving the water resistance of the adhesive. The addition of sodium carboxymethyl cellulose and lauroyl arginine ethyl ester hydrochloride further improves the wet shear strength of the adhesive, which is attributed to the electrostatic adsorption effect and the salt bridge hydrogen bond structure formed by the unique guanidine structure on lauroyl arginine ethyl ester hydrochloride with soybean meal and sodium carboxymethyl cellulose, respectively, which further improves the cross-linking density and energy dissipation of the system, thereby improving the water resistance of the adhesive.

[0069] Among them, the wet shear strength of the sustainable water-resistant and mildew-resistant soybean protein adhesive prepared in Example 5 reached 1.07 MPa, which was significantly higher than that of Comparative Examples 1-3.

[0070] 2. Anticorrosion experiment: The soy protein adhesives prepared in Example 5 of the present invention and Comparative Example 1 were placed in a constant temperature and humidity environment, and the corruption of the adhesives was observed and recorded within 0 to 8 days. The results are as follows: Figure 1 shown.

[0071] Depend on Figure 1 It can be seen that the pure soybean meal adhesive in Comparative Example 1 is very susceptible to mold erosion due to its rich nutrients, and it becomes corrupted in just one day, while the adhesive containing lauroyl arginine ethyl ester hydrochloride in Example 5 remains intact after being placed in a constant temperature and humidity environment for one week. This shows that the soybean protein adhesive prepared by the present invention has a good antiseptic effect and lasts for a long time.

[0072] 3. Antibacterial experiment: The soy protein adhesive prepared in Example 5 of the present invention and Comparative Example 1 were co-cultured with Staphylococcus aureus and Escherichia coli in a culture dish containing LB solid culture medium, and a culture medium containing Staphylococcus aureus / Escherichia coli without adding soy protein adhesive was used as a blank control. After 1 day, the antibacterial effect of soy protein adhesive on Staphylococcus aureus and Escherichia coli was calculated by plate colony counting method. The results are as follows: Figure 2 shown.

[0073] Depend on Figure 2 It can be seen that the pure soybean meal adhesive in Comparative Example 1 promotes the proliferation of bacteria due to the rich nutrients such as protein and polysaccharides in soybean meal, covering the entire culture dish. The adhesive containing lauroyl arginine ethyl ester hydrochloride in Example 5 shows excellent antibacterial properties against Staphylococcus aureus and Escherichia coli, and no bacterial growth is observed in the culture dish. This is because lauroyl arginine ethyl ester hydrochloride, as a cationic surfactant, can strongly interact with the negatively charged microbial cell surface, induce potential disorder and structural changes of microorganisms to change the permeability of cell membranes, and has a significant inhibitory effect on microorganisms such as bacteria, yeast, and molds, thereby playing an antibacterial role without the need to add additional antibacterial agents.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A sustainable water-resistant and mildew-resistant soybean protein adhesive, characterized in that: The invention is composed of the following raw materials in parts by weight: 15-35 parts of soybean meal, 55-75 parts of water, 2-6 parts of a cross-linking agent, 0.1-0.5 parts of sodium carboxymethyl cellulose and 0.5-2 parts of ethyl lauroyl arginine hydrochloride.

2. The sustainable water-resistant and mildew-resistant soybean protein adhesive according to claim 1, characterized in that: The soybean meal has a soybean protein content of 45-50% and a fineness of 75-85 meshes.

3. The sustainable water-resistant and mildew-resistant soybean protein adhesive according to claim 1, characterized in that: The cross-linking agent is triglycidylamine or ethylene glycol diglycidyl ether.

4. The sustainable water-resistant and mildew-resistant soybean protein adhesive according to claim 1, characterized in that: The mass of the cross-linking agent is 2-6% of the sum of the mass of soybean meal and water.

5. The sustainable water-resistant and mildew-resistant soybean protein adhesive according to claim 1, characterized in that: The mass of the sodium carboxymethyl cellulose is 0.1-0.2% of the sum of the mass of soybean meal and water.

6. The sustainable water-resistant and mildew-resistant soybean protein adhesive according to claim 1, characterized in that: The mass of the lauroyl arginine ethyl ester hydrochloride is 0.5-2% of the sum of the mass of soybean meal and water.

7. The sustainable water-resistant and mildew-resistant soybean protein adhesive according to claim 1, characterized in that: The sustainable water-resistant and mildew-proof soybean protein adhesive is composed of the following raw materials in parts by mass: 28 parts of soybean meal, 72 parts of water, 4 parts of a cross-linking agent, 0.15 parts of sodium carboxymethyl cellulose, and 1 part of ethyl lauroyl arginine hydrochloride; The mass of the cross-linking agent is 4% of the sum of the mass of soybean meal and water, the mass of the lauroyl arginine ethyl ester hydrochloride is 1% of the sum of the mass of soybean meal and water, and the mass of the sodium carboxymethyl cellulose is 0.15% of the sum of the mass of soybean meal and water.

8. The method for preparing the sustainable water-resistant and mildew-resistant soybean protein adhesive according to claim 1, characterized in that: The steps include: (1) dissolving sodium carboxymethyl cellulose and lauroyl arginine ethyl ester hydrochloride in water according to a ratio, stirring and mixing, and obtaining a composite solution of sodium carboxymethyl cellulose and lauroyl arginine ethyl ester hydrochloride; (2) adding soybean meal and a cross-linking agent into the composite solution of sodium carboxymethyl cellulose and ethyl lauroyl arginine hydrochloride obtained in step (1) according to a ratio, and mechanically stirring the mixture to obtain a sustainable water-resistant and mildew-resistant soybean protein adhesive.

9. The use of the sustainable water-resistant and mildew-resistant soybean protein adhesive according to claim 1, characterized in that: It is used in wood processing and artificial boards.

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