Preparation method of defatted bean flour adhesive based on multiple modification of ultrahigh pressure, monosaccharide and inorganic filler

Abstract

The invention discloses a preparation method of a defatted bean flour adhesive based on ultrahigh pressure, monosaccharide and inorganic filler multiple modification, and relates to the field of wooden furniture production and processing. The preparation method comprises the following steps: by taking defatted bean flour as a main raw material, firstly dispersing the defatted bean flour in deionized water, adding monosaccharide, uniformly stirring and mixing, then adding premixed inorganic filler and silane coupling agent, and performing vacuum sealing and ultrahigh pressure treatment to obtain the adhesive. The soybean protein space structure is destroyed through ultrahigh pressure, hydrophilic groups are consumed through monosaccharide crosslinking, an organic-inorganic hybrid system is constructed through inorganic filler, multiple synergistic modification is achieved, the problems that a traditional soybean adhesive is low in solid content, poor in water resistance and insufficient in bonding strength are effectively solved, and the prepared adhesive is high in solid content, good in fluidity, free of formaldehyde, environmentally friendly and suitable for large-scale production. The method is low in cost, suitable for industrial production and suitable for processing wood products such as plywood and shaving boards.

Description

Technical Field

[0001] This invention relates to the field of wooden furniture production and processing, and in particular to a method for preparing a defatted soybean flour adhesive with high solid content and water resistance based on multiple modifications of ultra-high pressure, monosaccharides, and inorganic fillers. Background Technology

[0002] Traditional wood adhesives primarily use urea-formaldehyde resin, phenolic resin, and melamine resin, which release formaldehyde during use, posing health risks and polluting the environment. Soybeans, with their abundant yield, environmental friendliness, and renewable nature, hold immense potential in the wood adhesive raw material market. Common soybean byproducts include soy protein isolate (SPI), soy protein concentrate (SPC), and defatted soy flour (DSF). Defatted soy flour (containing 50-60% soy protein) is the most cost-effective and suitable for practical production applications.

[0003] Soy protein molecules contain various hydrophilic groups, such as hydroxyl, carboxyl, and amino groups, and the interactions within the adhesive are easily disrupted in humid environments. Furthermore, due to the hydrophobic effect of proteins, during peptide chain folding and coiling, soybean protein tends to embed hydrophobic nonpolar groups in the center, exposing hydrophilic polar groups on the surface. This results in soybean adhesives typically exhibiting low bonding strength and poor water resistance, limiting their practical production applications. In addition, solid content also affects the application of defatted soybean flour adhesives. When the solid content of the adhesive is too low, on the one hand, the coated substrate surface is prone to insufficient adhesive, resulting in poor adhesion and low strength; on the other hand, the relatively high moisture content of the soybean adhesive is unfavorable for storage and leads to higher energy consumption during the hot pressing process of plywood or particleboard.

[0004] Common methods to increase the solid content of soybean adhesives include increasing the quality of soybean flour and filling with organic resins. However, these methods not only incur higher costs but may also result in higher viscosity, which is detrimental to the sizing process and affects the uniformity of adhesive coating on the substrate surface, thus impacting its bonding performance. Inorganic fillers are not only widely available but also inexpensive, making them a feasible method to increase the solid content and reduce the viscosity of defatted soybean flour adhesives. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of existing soybean adhesives, such as low solid content, poor moisture resistance, and insufficient bonding strength, and to provide a method for preparing a defatted soybean flour adhesive modified by ultra-high pressure, monosaccharides, and inorganic fillers. This method achieves simultaneous improvement in high solid content, high water resistance, and high bonding strength of the adhesive, while also being cost-controllable and environmentally friendly with no formaldehyde.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A method for preparing a defatted soybean flour adhesive based on multiple modifications using ultra-high pressure, monosaccharides, and inorganic fillers includes the following steps:

[0008] 1) Take 1 to 30 parts by weight of defatted soybean flour, add 10 to 100 parts of deionized water, and stir under a constant temperature water bath until the defatted soybean flour is evenly dispersed to obtain a defatted soybean flour solution.

[0009] 2) Take 1 to 10 parts of monosaccharide and add it to the defatted soybean flour solution. Continue stirring under a constant temperature water bath to obtain a monosaccharide-defatted soybean flour mixture.

[0010] 3) Take 1-20 parts of inorganic filler and 1-10 parts of silane coupling agent, mix them, and then add them to the monosaccharide-defatted soybean flour mixture. Continue stirring under a constant temperature water bath to obtain the defatted soybean flour mixture.

[0011] 4) Pack the defatted soybean flour mixture into a sealed bag and vacuum seal it;

[0012] 5) The vacuum-sealed defatted soybean flour mixture is subjected to ultra-high pressure treatment in an ultra-high pressure equipment to obtain defatted soybean flour adhesive.

[0013] In step 1), the defatted soybean flour can be commercially available defatted soybean flour with a protein content of 50% to 60%, the stirring temperature can be 25 to 60°C, and the stirring time can be 1 to 3 hours.

[0014] In step 2), the monosaccharide can be at least one of glucose, fructose, and xylose, preferably fructose; the stirring temperature can be 25-60°C, and the stirring time can be 1-3 hours.

[0015] In step 3), the inorganic filler can be montmorillonite with a purity of over 90%, the silane coupling agent can be KH550, the stirring temperature can be 25-60℃, and the stirring time can be 1-3h.

[0016] In step 4), the vacuum sealing time can be 20-60s, the heat sealing time can be 1-5s, and the heat sealing temperature can be 80-120℃.

[0017] In step 5), the conditions for ultra-high pressure treatment can be: treatment with water as the pressure transmission medium at a pressure of 100-600 MPa for a time of 3-60 min and a temperature of 20-30°C; the preferred conditions for ultra-high pressure treatment are 550 MPa and 25°C for 15-25 min.

[0018] The defatted soybean flour adhesive prepared by this method has a solid content ≥25%, an initial viscosity ≤500 Pa·s, a dry shear strength ≥2.0 MPa, and a wet shear strength ≥1.2 MPa.

[0019] This invention achieves the following technical effects through multiple synergistic modifications involving ultra-high pressure, monosaccharides, and inorganic fillers:

[0020] 1) Significantly Improved Performance: Ultra-high pressure disrupts the tertiary and quaternary spatial structures of soybean protein, exposing active groups within the protein. This improves the hydrophobicity of the adhesive and increases the reactive sites of the protein. Monosaccharides cross-link with the amino groups in soybean protein molecules, consuming hydrophilic groups and effectively reducing the hydrophilicity of the adhesive. Inorganic fillers are coupled with defatted soybean flour adhesive through silane coupling agents to construct an organic-inorganic hybrid system, further strengthening the intermolecular forces within the adhesive. The resulting defatted soybean flour adhesive has a maximum solid content of 31.05%, an initial viscosity reduced to 457 Pa·s, a dry shear strength ≥2.0 MPa, and a wet shear strength ≥1.2 MPa, fully meeting the performance requirements for adhesives used in wood furniture processing.

[0021] 2) Environmental and cost advantages: Using defatted soybean flour as the main raw material, the preparation process releases no formaldehyde, which meets the requirements of green environmental protection; all raw materials used are commercially available conventional products, the preparation process is simple, no complicated special equipment is required, the production cost is controllable, and it is suitable for large-scale industrial production.

[0022] 3) Strong application adaptability: It has high solid content, good flowability and excellent bonding performance, uniform coating and convenient glue application, and can be widely used in the production and processing of various wood products such as plywood, particleboard, solid wood furniture, and wood decorative panels. Attached Figure Description

[0023] Figure 1 A comparison of the dry and wet shear strengths of defatted soybean flour adhesives treated with different types of monosaccharides under the same pressure level.

[0024] Figure 2 A comparison of the dry and wet shear strengths of defatted soybean flour adhesives treated with different concentrations of montmorillonite under the same pressure and fructose concentration.

[0025] Figure 3 A comparison chart of the solid content of defatted soybean flour adhesives treated under different conditions.

[0026] Figure 4 Comparison of rheological properties of defatted soybean flour adhesives treated under different conditions. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The scope of protection of the present invention is not limited to the embodiments.

[0028] Example 1

[0029] Take 5g of defatted soybean flour and add it to 20mL of deionized water. Stir at 600r / min for 10min at 30℃. Then transfer the dispersed defatted soybean flour mixture to a sealed bag, label it sample 1, and seal it using a vacuum heat sealer. The vacuuming time is 40s, the heat sealing time is 2s, and the heat sealing temperature is 120℃. Place the sealed sample in an ultra-high pressure device and treat it under 100MPa pressure for 5min to obtain the modified defatted soybean flour adhesive.

[0030] Example 2

[0031] Take 5g of defatted soybean flour and add it to 20mL of deionized water. Stir at 600r / min for 10min at 30℃. Add 0.8g of glucose and continue stirring for 1h. Then transfer the dispersed defatted soybean flour mixture to a sealed bag, label it sample 2, and seal it using a vacuum heat sealer. The vacuuming time is 40s, the heat sealing time is 2s, and the heat sealing temperature is 120℃. Place the sealed sample in an ultra-high pressure device and treat it under 200MPa pressure for 10min to obtain the modified defatted soybean flour adhesive.

[0032] Example 3

[0033] Take 5g of defatted soybean flour and add it to 20mL of deionized water. Stir at 600r / min for 10min at 30℃. Add 1.0g of fructose and continue stirring for 1h. Then transfer the dispersed defatted soybean flour mixture to a sealed bag, label it sample 3, and seal it using a vacuum heat sealer. The vacuum time is 40s, the heat sealing time is 2s, and the heat sealing temperature is 120℃. Place the sealed sample in an ultra-high pressure device and treat it under 300MPa pressure for 10min to obtain the modified defatted soybean flour adhesive.

[0034] Example 4

[0035] Take 5g of defatted soybean flour and add it to 20mL of deionized water. Stir at 600r / min for 10min at 30℃. Add 1.2g of xylose and continue stirring for 1h. Then transfer the dispersed defatted soybean flour mixture to a sealed bag, label it sample 4, and seal it using a vacuum heat sealer. The vacuum time is 40s, the heat sealing time is 2s, and the heat sealing temperature is 120℃. Place the sealed sample in an ultra-high pressure device and treat it at 400MPa pressure for 10min to obtain the modified defatted soybean flour adhesive.

[0036] Example 5

[0037] Take 5g of defatted soybean flour and add it to 20mL of deionized water. Stir at 600r / min for 10min at 30℃. Add 1.0g of fructose and continue stirring for 1h. Then add 0.3g of KH550 and 0.5g of montmorillonite and continue stirring for 2h. Transfer the dispersed defatted soybean flour mixture to a sealed bag, label it sample 5, and seal it using a vacuum heat sealer. The vacuum time is 40s, the heat sealing time is 2s, and the heat sealing temperature is 120℃. Place the sealed sample in an ultra-high pressure device and treat it at 550MPa pressure for 15min to obtain the modified defatted soybean flour adhesive.

[0038] Example 6

[0039] Take 5g of defatted soybean flour and add it to 20mL of deionized water. Stir at 600r / min for 10min at 30℃. Add 1.0g of fructose and continue stirring for 1h. Then add 0.5g of KH550 and 1.0g of montmorillonite and continue stirring for 2h. Transfer the dispersed defatted soybean flour mixture to a sealed bag, label it sample 6, and seal it using a vacuum heat sealer. The vacuum time is 40s, the heat sealing time is 2s, and the heat sealing temperature is 120℃. Place the sealed sample in an ultra-high pressure device and treat it at 550MPa pressure for 20min to obtain the modified defatted soybean flour adhesive.

[0040] Example 7

[0041] Take 5g of defatted soybean flour and add it to 20mL of deionized water. Stir at 600r / min for 10min at 30℃. Add 1.0g of fructose and continue stirring for 1h. Then add 0.5g of KH550 and 1.5g of montmorillonite and continue stirring for 2h. Transfer the dispersed defatted soybean flour mixture to a sealed bag, label it sample 7, and seal it using a vacuum heat sealer. The vacuum time is 40s, the heat sealing time is 2s, and the heat sealing temperature is 120℃. Place the sealed sample in an ultra-high pressure device and treat it at 550MPa pressure for 25min to obtain the modified defatted soybean flour adhesive.

[0042] The defatted soybean flour adhesives obtained in Examples 1-7 were subjected to adhesive strength tests, and the specific test methods are as follows:

[0043] The wood used in the experiment was beech veneer, with dimensions of 50mm × 20mm × 2mm. Adhesive was applied by coating, covering an area of ​​20mm × 20mm, with a single-sided coating amount of 100g / m². 2After coating, the wood panels were placed at room temperature and 50% humidity for 10 minutes, followed by hot pressing at 130℃ and 23MPa for 10 minutes. The hot-pressed panels were then left at room temperature for 24 hours, and then divided into two groups. One group was used to test dry bond strength, and the other group was immersed in a 63℃ water bath for 3 hours before being tested for wet bond strength. Both groups of wood panels were tested according to the relevant provisions of the national standard GB / T9846.3-2004. Eight parallel samples of each adhesive were prepared for each group of wood panels.

[0044] Figure 1 A comparison of the dry and wet shear strengths of defatted soybean flour adhesives treated with different types of monosaccharides under the same pressure level is presented. Figure 1 As can be seen, monosaccharide modification can improve the dry and wet shear strength of adhesives, with fructose modification showing the best effect.

[0045] Figure 2 A comparison of the dry and wet shear strengths of defatted soybean flour adhesives treated with different concentrations of montmorillonite under the same pressure and fructose concentration is presented. Figure 2 It can be seen that the adhesive synthesized with 4% montmorillonite has the best dry and wet shear strength, and the strength begins to decrease after the amount of montmorillonite added is increased.

[0046] Figure 3 A comparison chart of the solid content of defatted soybean flour adhesives treated under different conditions is provided. From... Figure 3 As can be seen, the addition of montmorillonite increased the solid content of defatted soybean flour-based adhesives, with the highest solid content being 31.05%.

[0047] Figure 4 Rheological comparison graphs of defatted soybean flour adhesives treated under different conditions are presented. From Figure 4 As can be seen, the addition of montmorillonite reduces the high viscosity caused by ultra-high pressure and monosaccharide modification, and the initial viscosity of the montmorillonite-modified defatted soybean flour adhesive is reduced to 457 Pa·s.

[0048] This invention uses defatted soybean flour as the main raw material and modifies soybean protein through ultra-high pressure technology, monosaccharides, and inorganic fillers. The synergistic effect of the triple modification is not a simple additive but rather mutually reinforcing: ultra-high pressure exposes the active sites of the protein, providing conditions for monosaccharide cross-linking; monosaccharide cross-linking reduces hydrophilicity, laying the foundation for uniform dispersion of inorganic fillers; and inorganic fillers construct a hybrid system, further enhancing the effects of ultra-high pressure and monosaccharide modification, achieving a leapfrog improvement in performance. This results in improved bonding strength, moisture resistance, and solid content of defatted soybean flour adhesives, which are not only cost-controllable but also have advantages such as being formaldehyde-free, environmentally friendly, easy to process, and easy to apply.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments without departing from the inventive concept and technical principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a defatted soybean flour adhesive based on multiple modifications using ultra-high pressure, monosaccharides, and inorganic fillers, characterized in that, Includes the following steps: 1) Take 1 to 30 parts by weight of defatted soybean flour, add 10 to 100 parts of deionized water, and stir under a constant temperature water bath until the defatted soybean flour is evenly dispersed to obtain a defatted soybean flour solution. 2) Take 1 to 10 parts of monosaccharide and add it to the defatted soybean flour solution. Continue stirring under a constant temperature water bath to obtain a monosaccharide-defatted soybean flour mixture. 3) Take 1-20 parts of inorganic filler and 1-10 parts of silane coupling agent, mix them evenly, and then add them to the monosaccharide-defatted soybean flour mixture. Continue stirring under a constant temperature water bath to obtain the defatted soybean flour mixture. 4) Pack the defatted soybean flour mixture into a sealed bag and vacuum seal it; 5) The vacuum-sealed defatted soybean flour mixture is placed in an ultra-high pressure device for ultra-high pressure treatment to obtain defatted soybean flour adhesive.

2. The preparation method of the defatted soybean flour adhesive based on multiple modifications of ultra-high pressure, monosaccharides, and inorganic fillers according to claim 1, characterized in that, In step 1), the defatted soybean flour used is commercially available defatted soybean flour with a protein content of 50% to 60%, the stirring temperature is 25 to 60°C, and the stirring time is 1 to 3 hours.

3. The preparation method of the defatted soybean flour adhesive based on multiple modifications of ultra-high pressure, monosaccharides, and inorganic fillers according to claim 1, characterized in that, In step 2), the monosaccharide is at least one of glucose, fructose, and xylose, the stirring temperature is 25-60℃, and the stirring time is 1-3h.

4. The preparation method of the defatted soybean flour adhesive based on multiple modifications of ultra-high pressure, monosaccharides, and inorganic fillers according to claim 3, characterized in that, The monosaccharide used is fructose.

5. The preparation method of a defatted soybean flour adhesive based on multiple modifications of ultra-high pressure, monosaccharides, and inorganic fillers according to claim 1, characterized in that, In step 3), the inorganic filler is montmorillonite with a purity of ≥90%, the silane coupling agent is KH550, the stirring temperature is 25~60℃, and the stirring time is 1~3h.

6. The preparation method of a defatted soybean flour adhesive based on multiple modifications of ultra-high pressure, monosaccharides, and inorganic fillers according to claim 1, characterized in that, In step 4), the parameters for vacuum sealing are: vacuuming time 20-60s, heat sealing time 1-5s, and heat sealing temperature 80-120℃.

7. The preparation method of a defatted soybean flour adhesive based on multiple modifications of ultra-high pressure, monosaccharides, and inorganic fillers according to claim 1, characterized in that, In step 5), the conditions for ultra-high pressure treatment are: water as the pressure transmission medium, pressure 100-600 MPa, temperature 20-30℃, and treatment time 3-60 min.

8. The preparation method of a defatted soybean flour adhesive based on multiple modifications of ultra-high pressure, monosaccharides, and inorganic fillers according to claim 7, characterized in that, The ultra-high pressure treatment conditions are: 550 MPa, 25℃ for 15-25 minutes.

9. A defatted soybean flour adhesive, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. The defatted soybean flour adhesive according to claim 9, characterized in that, The defatted soybean flour adhesive has a solid content of ≥25%, an initial viscosity of ≤500 Pa·s, a dry shear strength of ≥2.0 MPa, and a wet shear strength of ≥1.2 MPa.

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