A gelatin-modified, strong soybean protein water-based adhesive and its preparation method

Abstract

This invention discloses a gelatin-modified, strong, water-based adhesive for soybean protein and its preparation method. The adhesive comprises the following components in parts by weight: 25 parts soybean protein, 0-4.5 parts gelatin-A, 0-4.5 parts gelatin-B, and 75 parts dispersion medium. The specific steps of the preparation method for the gelatin-modified, strong, water-based adhesive for soybean protein are as follows: S1, Weigh each component according to the mass ratio, disperse gelatin-A and gelatin-B in the dispersion medium, and stir at 40°C in a water bath until gelatin-A and gelatin-B are completely dissolved; S2, Disperse soybean protein evenly in the dispersion of gelatin-A and gelatin-B obtained in step S1, and then stir at high speed for 5 minutes. This gelatin-modified, strong, water-based adhesive for soybean protein and its preparation method can generate an adhesive that can be connected to various matrices through hydrogen bonding, electrostatic interaction, or mechanical interlocking, thereby achieving strong adhesion.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a gelatin-modified, strong soybean protein water-based adhesive and its preparation method. Background Technology

[0002] Adhesives are ubiquitous in our lives, found in construction, airplanes, automobiles, furniture, shoes, and packaging. While traditional synthetic adhesives offer advantages in terms of high performance and low cost, they also cause significant environmental problems. The petroleum-based raw materials used in traditional adhesives are non-renewable and increasingly scarce. They release toxic gases during use; for example, formaldehyde-based adhesives used in engineered wood products release carcinogenic formaldehyde. Waste adhesives are difficult to chemically degrade, exacerbating the microplastic problem.

[0003] Sustainable materials such as natural proteins and polysaccharides show great potential in replacing existing petroleum-based polymers. Protein meal, a byproduct of defatting natural plants, is abundant and inexpensive. Globulins and polysaccharides are major components of plant proteins; however, their interaction relies on limited secondary bond interactions. In the preparation of protein adhesives, they lack sustainable and efficient energy dissipation pathways, such as molecular chain entanglement, crystallization, and covalent cross-linking, resulting in lower mechanical properties (strength and toughness). Performance and cost are perennial concerns when developing novel adhesive products for sustainable development. Therefore, developing high-performance, low-cost, sustainable bio-based adhesives is a significant challenge. 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] Therefore, the purpose of this invention is to provide a gelatin-modified strong soybean protein aqueous adhesive and its preparation method. The resulting adhesive can be connected to various matrices through hydrogen bonding, electrostatic interaction or mechanical interlocking, thereby achieving strong adhesion.

[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 gelatin-modified, tough, water-based adhesive for soybean protein, comprising the following components in parts by weight: 25 parts soybean protein, 0-4.5 parts gelatin-A, 0-4.5 parts gelatin-B, and 75 parts dispersion medium.

[0008] In a preferred embodiment of the gelatin-modified strong soybean protein water-based adhesive of the present invention, gelatin-A is 0 parts and gelatin-B is 4.5 parts, or gelatin-A is 4.5 parts and gelatin-B is 0 parts, or gelatin-A is 1.5 parts and gelatin-B is 3 parts, or gelatin-A is 3 parts and gelatin-B is 1.5 parts.

[0009] As a preferred embodiment of the gelatin-modified strong soybean protein water-based adhesive of the present invention, the soybean protein contains 53% protein and 33% carbohydrates.

[0010] In a preferred embodiment of the gelatin-modified strong soybean protein water-based adhesive of the present invention, the soybean protein has a particle size of less than 200 mesh.

[0011] In a preferred embodiment of the gelatin-modified strong soybean protein water-based adhesive of the present invention, the dispersion medium is tap water or deionized water.

[0012] A method for preparing a gelatin-modified, strong, water-based soybean protein adhesive, comprising the following specific steps:

[0013] S1. Weigh each component according to the mass ratio, disperse gelatin-A and gelatin-B in the dispersion medium, and stir under a 40°C water bath to completely dissolve gelatin-A and gelatin-B;

[0014] S2. Disperse the soybean protein evenly in the gelatin-A and gelatin-B dispersions obtained in step S1, and then stir at high speed for 5 minutes.

[0015] In a preferred embodiment of the preparation method of the gelatin-modified strong soybean protein aqueous adhesive of the present invention, the gelatin-B is obtained by enzymatic hydrolysis of gelatin-A, and the preparation method of gelatin-B is as follows: Gelatin-B is obtained by enzymatic hydrolysis of gelatin-A, specifically as follows:

[0016] First, add 10g of gelatin-A to a beaker containing 40g of deionized water and stir at 55℃ for 10 minutes;

[0017] Then add 0.01g of bromelain to the beaker and stir at 600 rpm for 30 seconds;

[0018] The beaker was then quickly transferred to hot water at 95°C and stirred for 20 minutes to deactivate the bromelain. Finally, solid gelatin-B powder was obtained by freeze-drying.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. This invention uses gelatin-modified soybean protein adhesive. Gelatin-A and gelatin-B form a network backbone through molecular self-assembly, which interacts with soybean protein through hydrogen bonds, thereby improving the strength and toughness of the adhesive.

[0021] 2. The use of gelatin-B in this invention helps to uniformly disperse soybean globulin, promotes the interaction between globulin and the bonding interface, and improves the interfacial adhesion performance of the adhesive.

[0022] 3. As a room temperature adhesive, this invention does not contain formaldehyde or other volatile organic compounds, thus solving the problems of petroleum resource consumption and indoor air pollution caused by traditional synthetic adhesives. Attached Figure Description

[0023] 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 detailed 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:

[0024] Figure 1 A schematic diagram of the molecular weight of gelatin in various embodiments provided by the present invention;

[0025] Figure 2 These are morphological images of the cured adhesive layer in Example 3 of the present invention and a conventional adhesive.

[0026] Figure 3 The adhesive used in Examples 1-4 of this invention is shown in the lap shear strength test diagram of the wood-to-steel specimens.

[0027] Figure 4 The image shows the test results of the lap shear strength of the adhesive on different substrates in Example 3 of this invention. Detailed Implementation

[0028] 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.

[0029] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

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

[0031] This invention provides a gelatin-modified strong soybean protein aqueous adhesive and its preparation method. The resulting adhesive can be connected to various matrices through hydrogen bonding, electrostatic interaction or mechanical interlocking, thereby achieving strong adhesion.

[0032] This gelatin-modified, tough, water-based soybean protein adhesive comprises the following components in parts by weight: 25 parts soybean protein, 0-4.5 parts gelatin-A, 0-4.5 parts gelatin-B, and 75 parts dispersion medium. Specifically, gelatin-A is 0 parts and gelatin-B is 4.5 parts, or gelatin-A is 4.5 parts and gelatin-B is 0 parts, or gelatin-A is 1.5 parts and gelatin-B is 3 parts, or gelatin-A is 3 parts and gelatin-B is 1.5 parts. The soybean protein contains 53% protein and 33% carbohydrates, and the particle size of the soybean protein is less than 200 mesh. In this embodiment, the molecular weights of gelatin-A and gelatin-B are as follows: Figure 1 As shown.

[0033] To verify the gelatin-modified strong soybean protein water-based adhesive of the present invention, the following Examples 1-4 are provided.

[0034] Example 1

[0035] A method for preparing a gelatin-modified, strong, water-based soybean protein adhesive includes the following steps:

[0036] S1. Add 4.5g of gelatin-B to 75g of deionized water and stir in a 40℃ water bath until gelatin-B is completely dissolved.

[0037] S2. Add 25g of soy protein to the mixture obtained in step S1 and stir for 5 minutes to disperse evenly; wherein, gelatin-B is obtained from gelatin-A through enzymatic hydrolysis, as detailed below:

[0038] First, add 10g of gelatin-A to a beaker containing 40g of deionized water and stir at 55℃ for 10 minutes;

[0039] Then add 0.01g of bromelain to the beaker and stir at 600 rpm for 30 seconds;

[0040] The beaker was then quickly transferred to hot water at 95°C and stirred for 20 minutes to deactivate the bromelain. Finally, solid gelatin-B powder was obtained by freeze-drying.

[0041] Example 2

[0042] A method for preparing a gelatin-modified, strong, water-based soybean protein adhesive includes the following steps:

[0043] S1. Add 1.5g of gelatin-A and 3g of gelatin-B to 75g of deionized water and stir in a 40℃ water bath until gelatin-A and gelatin-B are completely dissolved.

[0044] S2. Add 25g of soy protein to the mixture obtained in step S1, and stir for 5 minutes to disperse evenly. Gelatin-B is obtained from gelatin-A through enzymatic hydrolysis, as detailed below:

[0045] First, add 10g of gelatin-A to a beaker containing 40g of deionized water and stir at 55℃ for 10 minutes;

[0046] Then add 0.01g of bromelain to the beaker and stir at 600 rpm for 30 seconds;

[0047] The beaker was then quickly transferred to hot water at 95°C and stirred for 20 minutes to deactivate the bromelain. Finally, solid gelatin-B powder was obtained by freeze-drying.

[0048] Example 3

[0049] A method for preparing a gelatin-modified, strong, water-based soybean protein adhesive includes the following steps:

[0050] S1. Add 3g of gelatin-A and 1.5g of gelatin-B to 75g of deionized water and stir in a 40°C water bath until gelatin-A and gelatin-B are completely dissolved.

[0051] S2. Add 25g of soy protein to the mixture obtained in step S1 and stir for 5 minutes until evenly dispersed; Gelatin-B is obtained from gelatin-A through enzymatic hydrolysis, as detailed below:

[0052] First, add 10g of gelatin-A to a beaker containing 40g of deionized water and stir at 55℃ for 10 minutes;

[0053] Then, 0.01g of bromelain was added to the beaker and stirred at 600 rpm for 30 seconds. The beaker was then quickly transferred to hot water at 95°C and stirred for 20 minutes to deactivate the bromelain. Finally, solid gelatin-B powder was obtained by freeze drying.

[0054] Example 4

[0055] A method for preparing a gelatin-modified, strong, water-based soybean protein adhesive includes the following steps:

[0056] S1. Add 4.5g of gelatin-A to 75g of deionized water and stir in a 40℃ water bath until gelatin-A is completely dissolved.

[0057] S2. Add 25g of soy protein to the mixture obtained in step S1 and stir for 5 minutes to disperse it evenly.

[0058] Comparative Examples 1-3

[0059] Comparative Examples 1-3 used commercially available water-based adhesives, including polyvinyl acetate emulsion (PVAc), ethylene-vinyl acetate copolymer emulsion (EVA), and starch adhesive, as comparative experiments.

[0060] The modified soybean protein adhesives prepared in Examples 1-4 and the aqueous adhesives in Comparative Examples 1-3 of the present invention were subjected to performance tests according to the following methods:

[0061] Adhesive performance evaluation experiment

[0062] The bond strength of the adhesives in Examples 1-4 and Comparative Examples 1-3 to various substrates was primarily evaluated using lap shear test specimens. Considering that the room temperature curing of these adhesives is achieved through moisture evaporation, wood was used as one of the substrates for the shear test specimens. Shear test specimens were prepared from wood, steel, glass, alumina ceramics, calcium silicate cement, fabric, and cardboard. Except for glass and fabric (25 × 1 × 100 mm), the thickness of the shear test specimens was also considered. 3 In addition, all substrate dimensions are 25×2×100mm. 3 Apply approximately 0.15g of adhesive to one end of the substrate board, then place the wooden board on top, checking that it measures approximately 25×25mm. 2 The overlapping areas were clamped together with two dovetail clips to ensure a good fit. The prepared shear specimens were left to cure to equilibrium under ambient conditions (25°C, 40% humidity) for 24 hours. All shear specimens were tested using INSTRON 3366 at a tensile speed of 10 mm / min. The maximum force was recorded and then divided by the bonded area to calculate the shear strength. Three specimens were used in each group, and the average value was taken.

[0063] The adhesives used in Examples 1-4 were applied to the lap shear strength test of wood-to-steel specimens, as shown in Table 1 and... Figure 2 As shown in Table 2, the lap shear strength tests of the adhesive in Example 3 and the adhesives in Comparative Examples 1-3 on different substrates are shown in Table 2.

[0064] Table 1 - Adhesive application in Examples 1-4: Shear strength (MPa) of wood-to-steel specimens

[0065] test sample Timber-to-steel lap joint shear strength Example 1 2.83 Example 2 3.28 Example 3 3.65 Example 4 3.48

[0066] Table 2 - Overlap shear strength (MPa) of the adhesives in Example 3 and Comparative Examples 1-3 for different substrates.

[0067] test sample Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 wood against wood 3.51 3.68 3.06 2.42 wood versus steel 3.65 0.72 2.65 1.74 wood against glass 2.47 0.82 1.56 0.85 Wood against ceramics 2.58 1.96 1.78 1.54 wood against cement 1.33 1.23 1.35 1.26 Wood against paper 1.08 1.01 1.15 1.10 Wood to fabric 0.62 0.58 0.65 0.56

[0068] As shown in Table 2, compared to the comparative example, the adhesive of this application exhibits superior overall performance, is derived from biomass raw materials, and is more sustainable. The toughness of the cured adhesive layer was assessed by observing the surface morphology of the cured film; the experimental results are as follows. Figure 2 As shown, the soybean protein adhesive of the present invention does not have the problems of formaldehyde release and petroleum-based raw material consumption. The cured adhesive layer has fewer pores and cracks on its surface, forming a uniform and dense adhesive layer. Furthermore, as... Figure 4 As shown, in the examples, the soybean protein adhesive exhibits an overlap shear strength of over 3.5 MPa for wood and steel, indicating that the toughness of the modified adhesive has been improved.

[0069] In summary, the invented adhesive mainly consists of a soybean flour matrix and a gelatin backbone. Soybean flour contains globular proteins and polysaccharides, which enhance interfacial adhesion and withstand loads. Gelatin-A, after enzymatic hydrolysis, yields gelatin-B with a smaller molecular weight. Some gelatin-A and gelatin-B segments self-assemble into a collagen triple helix structure, forming a stable three-dimensional network backbone that primarily maintains the cohesive force of the adhesive system and promotes the interfacial adhesion of soybean globulins. The soybean protein matrix and the gelatin-A / gelatin-B backbone are linked together through hydrogen-bonded supramolecular interactions. The resulting adhesive can connect to various matrices via hydrogen bonds, electrostatic interactions, or mechanical interlocking, thereby achieving strong and durable adhesion. This adhesive possesses tunable and convenient application characteristics, such as room temperature bonding and on-demand separation.

[0070] 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 gelatin-modified, strong, water-based soybean protein adhesive, characterized in that, It consists of the following components in parts by weight: 25 parts soy protein, 0-4.5 parts gelatin-A, 1.5-4.5 parts gelatin-B, and 75 parts dispersion medium; The gelatin-B is obtained by enzymatic hydrolysis of gelatin-A, and the preparation method of gelatin-B is as follows: First, add 10g of gelatin-A to a beaker containing 40g of deionized water and stir at 55℃ for 10 minutes; Then add 0.01g of bromelain to the beaker and stir at 600 rpm for 30 seconds; The beaker was then quickly transferred to hot water at 95°C and stirred for 20 minutes to deactivate the bromelain. Finally, solid gelatin-B powder was obtained by freeze-drying.

2. The gelatin-modified, strong, water-based soybean protein adhesive according to claim 1, characterized in that, Gelatin-A is 0 parts and gelatin-B is 4.5 parts, or gelatin-A is 1.5 parts and gelatin-B is 3 parts, or gelatin-A is 3 parts and gelatin-B is 1.5 parts.

3. The gelatin-modified, strong, soybean protein water-based adhesive according to claim 1, characterized in that, The soy protein contains 53% protein and 33% carbohydrates.

4. The gelatin-modified, strong, soybean protein water-based adhesive according to claim 1, characterized in that, The particle size of the soybean protein is less than 200 mesh.

5. The gelatin-modified, strong, water-based soybean protein adhesive according to claim 1, characterized in that, The dispersion medium is tap water or deionized water.

6. A method for preparing a gelatin-modified, strong, water-based soybean protein adhesive as described in any one of claims 1-5, characterized in that, The specific steps are as follows: S1. Weigh each component according to the mass ratio, disperse gelatin-A and gelatin-B in the dispersion medium, and stir under a 40°C water bath to completely dissolve gelatin-A and gelatin-B; S2. Disperse the soybean protein evenly in the gelatin-A and gelatin-B dispersions obtained in step S1, and then stir at high speed for 5 minutes.

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