Preparation and use method of a biomass super-strong universal adhesive

Abstract

The present invention discloses a method for preparing and using a biomass-based, ultra-strong, all-purpose adhesive, belonging to the technical field of adhesives. The invention utilizes aminated cellulose as a backbone, grafted with amino groups. The amino groups react with the quinone groups of oxidized tannins to form imine bonds, thereby forming a stable cross-linked network. Glycerol triglycidyl ether is then added, and the epoxy groups in the glycerol triglycidyl ether further react with the amino groups and even hydroxyl groups. Through a series of covalent and non-covalent interactions, the adhesive's cohesive force is synergistically enhanced, resulting in a biomass-based, ultra-strong, all-purpose adhesive capable of high-performance bonding to a variety of substrates, without the need for pressure.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to a preparation and use method of a biomass super-strong universal adhesive. Background Art

[0002] Structural adhesives, due to their high strength, high load-bearing capacity, impact resistance, corrosion resistance, and ease of coating and application, are widely used in a wide range of industries, including aerospace, automotive, construction, electronics, machinery manufacturing, and rail transportation. However, the synthetic raw materials for existing structural adhesives, such as epoxy resins, polyurethanes, and acrylates, are mostly derived from fossil resources and are non-renewable. With increasing environmental awareness and government policies, the production cost and supply stability of traditional adhesives are facing challenges. Utilizing biomass resources can reduce dependence on fossil energy, lower carbon emissions, and meet the requirements of sustainable development.

[0003] Cellulose is a natural polymer compound that can be decomposed and degraded by microorganisms in the natural environment, without causing long-term environmental pollution or harm. This aligns with the concept of sustainable development and can be used to prepare biomass-based structural adhesives. For example, existing patent CN114836149A discloses an amine-functionalized modified cellulose cross-linked network structure, its preparation method, and its application. This patent utilizes aminated cellulose and trimethylolpropane triglycidyl ether to prepare an environmentally friendly cellulose cross-linked network wood adhesive.

[0004] Tannic acid, also known as tannic acid, is a polyphenolic compound found in a wide variety of plants, such as the bark and fruit of trees like oak and sumac. It can replace common raw materials such as phenol and resorcinol in wood-based panel adhesives and can be used in the preparation of biomass-based structural adhesives. For example, patent CN115353850A discloses an environmentally friendly, water-resistant tannin-based wood adhesive and its preparation method. The adhesive is synthesized using epoxidized tannin, triethylenetetramine, and urea as the main raw materials through graft copolymerization and deamination reactions.

[0005] However, the adhesives prepared by the above-mentioned prior art need to be hot-pressed under a certain pressure during use to achieve a good bonding effect. If the pressure is omitted, even if the heating time is extended, a good bonding effect cannot be achieved. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention proposes a preparation and use method of a biomass super-strong universal adhesive.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a biomass super-strong universal adhesive, comprising the following steps:

[0009] The aminated cellulose is dispersed in an oxidized tannin aqueous solution, homogenized, and glycerol triglycidyl ether is added, stirred to obtain a viscous liquid and an aqueous phase, and the obtained viscous liquid is separated to obtain the biomass super-strong universal adhesive.

[0010] Preferably, the mass ratio of the aminated cellulose, the oxidized tannin aqueous solution and glycerol triglycidyl ether is 3:11:(3-5).

[0011] Preferably, the aminated cellulose is obtained by reacting microcrystalline cellulose and aminopropyltriethoxysilane.

[0012] Preferably, the oxidized tannin aqueous solution is obtained by reacting hydrogen peroxide with a tannin aqueous solution.

[0013] Preferably, the solid content of the oxidized tannin aqueous solution is 20-40%.

[0014] The present invention provides a biomass super-strong multi-purpose adhesive prepared by the preparation method described in the above technical solution.

[0015] The present invention also provides a method for using the biomass super-strong universal adhesive described in the above technical solution, comprising the following steps: overlapping different substrates using the biomass super-strong universal adhesive, and curing them at room temperature or by heating to complete the bonding of different substrates.

[0016] Preferably, the room temperature curing time is 72 to 240 hours.

[0017] Preferably, the temperature of the heating curing is 60-120° C., and the time is 0.5-1 h.

[0018] Preferably, the substrate includes one or more of wood, bamboo, stainless steel, aluminum, iron, copper, glass, marble, artificial quartz stone, zirconium oxide, and cloth.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects:

[0020] The present invention uses aminated cellulose as a skeleton, and the aminated cellulose is grafted with amino groups. The amino groups can undergo a Schiff base reaction with the quinone groups of oxidized tannins to form imine bonds, thereby forming a stable cross-linked network. Then, glycerol triglycidyl ether is added, and the epoxy groups in the glycerol triglycidyl ether further react with the amino groups and even the hydroxyl groups. Through a series of covalent and non-covalent interactions, the cohesive force of the adhesive is synergistically enhanced, thereby obtaining a biomass super-strong universal adhesive that can perform high-performance bonding on a variety of substrates, and bonding can be achieved without applying pressure. It is expected to achieve commercial production and sales and partially replace existing synthetic resin adhesives on the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 This is a reaction process diagram for preparing aminated cellulose from microcrystalline cellulose and APTES in step (1) of Example 1 of the present invention;

[0023] Figure 2 This is a reaction process diagram for preparing oxidized tannin from tannin and hydrogen peroxide in step (2) of Example 1 of the present invention;

[0024] Figure 3 is the structural formula of glycerol triglycidyl ether in step (3) of Example 1 of the present invention;

[0025] Figure 4 This is a schematic structural diagram of the biomass super-strong multi-purpose adhesive prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The embodiment of the present invention provides a method for preparing a biomass super-strong multi-purpose adhesive, comprising the following steps:

[0029] Aminated cellulose (AC) is dispersed in an oxidized tannin (OTA) aqueous solution, homogenized, and then glycerol triglycidyl ether (GTE) is added and stirred to obtain a viscous liquid and an aqueous phase. The obtained viscous liquid is separated to obtain the biomass super strong all-purpose adhesive (ATG adhesive).

[0030] The present invention uses aminated cellulose as a skeleton, and the aminated cellulose is grafted with amino groups. The amino groups can undergo a Schiff base reaction with the quinone groups of oxidized tannins to form imine bonds, thereby forming a stable cross-linked network. Then, glycerol triglycidyl ether is added, and the epoxy groups in the glycerol triglycidyl ether further react with the amino groups and even the hydroxyl groups. Through a series of covalent and non-covalent interactions, the cohesive force of the adhesive is synergistically enhanced, thereby obtaining a biomass super-strong universal adhesive that can perform high-performance bonding on a variety of substrates, and bonding can be achieved without applying pressure. It is expected to achieve commercial production and sales and partially replace existing synthetic resin adhesives on the market.

[0031] In a preferred embodiment, the mass ratio of the aminated cellulose, oxidized tannin aqueous solution, and glycerol triglycidyl ether is 3:11:(3-5). Since the aminated cellulose has amino groups grafted onto its molecular structure and the oxidized tannin has quinone groups, the aminated cellulose and oxidized tannins are cross-linked via a Schiff base reaction, while glycerol triglycidyl ether utilizes epoxy groups to react with amino or hydroxyl groups to join the cross-linked network. Therefore, the ratio of the three raw materials will affect the number of corresponding groups, thereby affecting the degree of reaction. The present invention controls the mass ratio of aminated cellulose, oxidized tannin aqueous solution, and glycerol triglycidyl ether within the above range, resulting in the best state and bonding performance of the biomass super-strong multi-purpose adhesive. Changing the mass ratio of the three will deteriorate the bonding performance of the adhesive.

[0032] In a preferred embodiment, the aminated cellulose is obtained by reacting microcrystalline cellulose and aminopropyltriethoxysilane (APTES); wherein the reaction principle of microcrystalline cellulose and aminopropyltriethoxysilane is shown in Figure 1 .

[0033] The ratio of microcrystalline cellulose to aminopropyltriethoxysilane determines the extent of amino group grafting. The greater the amount of aminopropyltriethoxysilane used, the more amino groups are grafted onto the microcrystalline cellulose, which facilitates subsequent cross-linking and polymerization with oxidized tannins and glycerol triglycidyl ether. The inventors have experimentally verified that a mass ratio of microcrystalline cellulose to aminopropyltriethoxysilane of 20:18 achieves the maximum amino group grafting. Therefore, in a preferred embodiment, the mass ratio of microcrystalline cellulose to aminopropyltriethoxysilane is 20:18.

[0034] In a preferred embodiment, the preparation method of the aminated cellulose is as follows: microcrystalline cellulose and aminopropyltriethoxysilane are dispersed in water, stirred for reaction, filtered, washed and dried to obtain the aminated cellulose.

[0035] In a preferred embodiment, the mass ratio of the microcrystalline cellulose, aminopropyltriethoxysilane and water is 20:18:100; the stirring reaction temperature is room temperature and the time is 24 hours; the washing reagent is deionized water; the drying temperature is 80°C and the equipment is an oven.

[0036] In a preferred embodiment, the oxidized tannin aqueous solution is obtained by reacting hydrogen peroxide with a tannin aqueous solution; wherein the reaction principle of hydrogen peroxide and tannin is shown in Figure 2 .

[0037] In a preferred embodiment, the mass ratio of hydrogen peroxide to tannin in the tannin aqueous solution is 0.5:3.4.

[0038] In a preferred embodiment, the preparation method of the oxidized tannin aqueous solution is specifically: dispersing tannin in water, then adding hydrogen peroxide, and stirring to obtain the oxidized tannin aqueous solution.

[0039] In a preferred embodiment, the mass ratio of hydrogen peroxide, tannin and water is 0.5:3.4:7.9; the stirring temperature is room temperature, and the stirring time is 10 minutes.

[0040] In a preferred embodiment, the solid content of the oxidized tannin aqueous solution is 20-40%. The solid content of the oxidized tannin aqueous solution in the present invention is within the above range, which is just enough to disperse the corresponding amount of aminated cellulose, without wasting water resources due to excessive water or poor dispersibility of the aminated cellulose due to insufficient water.

[0041] In a preferred embodiment, the homogenizing method is stirring.

[0042] The present invention provides a biomass super-strong multi-purpose adhesive prepared by the preparation method described in the above technical solution.

[0043] The biomass super-strong universal adhesive provided by the present invention has excellent gluing properties and can perform high-performance bonding on a variety of substrates without applying pressure.

[0044] The present invention also provides a method for using the biomass super-strong universal adhesive described in the above technical solution, comprising the following steps: overlapping different substrates using the biomass super-strong universal adhesive, and curing them at room temperature or by heating to complete the bonding of different substrates.

[0045] In a preferred embodiment, the method of overlapping different substrates using the biomass super-strong universal adhesive is as follows: applying the biomass super-strong universal adhesive to one side of the surface of different substrates to form a bonding area, and then overlapping the bonding areas of the different substrates.

[0046] In a preferred embodiment, the substrate types of the different substrates may be the same or different.

[0047] In a preferred embodiment, the amount of the biomass super strong universal adhesive applied is 0.5mm 2 / g.

[0048] In a preferred embodiment, the room temperature curing time is 72 to 240 hours; no pressurization is required. While room temperature curing takes a relatively long time, it results in slower water evaporation, a denser adhesive layer, and lower energy consumption. Bonding performance improves with increasing curing time, making it suitable for long-lasting, energy-efficient bonding.

[0049] In a preferred embodiment, the heat curing temperature is 60-120°C and the time is 0.5-1 hour; the heat curing does not require pressure. Heat curing quickly evaporates water, significantly shortening the curing time, effectively improving the efficiency of use, and is suitable for rapid bonding.

[0050] In a preferred embodiment, the substrate includes one or more of wood, bamboo, stainless steel, aluminum, iron, copper, glass, marble, artificial quartz stone, zirconium oxide, and cloth.

[0051] The room temperature in the embodiments of the present invention refers to "25±3°C".

[0052] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0053] In the following examples, the substrates used were purchased from the local market. The green and yellow bamboo leaves of the bamboo were removed, and the surface of the metal substrate was polished smooth.

[0054] Glycerol triglycidyl ether is an industrial grade chemical purchased from Wuhan Smack Biotechnology Co., Ltd. The structural formula is shown in Figure 3 .

[0055] Example 1

[0056] A preparation method of a biomass super-strong universal adhesive:

[0057] (1) 20 g of microcrystalline cellulose and 18 g of APTES were dispersed in 100 g of water, stirred at room temperature for 24 h, filtered, rinsed with deionized water, and then dried in an oven at 80 °C to obtain aminated cellulose (AC);

[0058] (2) Disperse 3.4 g of tannin in 7.9 g of water, then add 0.5 g of hydrogen peroxide and stir at room temperature for 10 min to obtain an amber-colored homogeneous and transparent liquid, which is the oxidized tannin (OTA) aqueous solution;

[0059] (3) 3 g of AC obtained in step (1) was dispersed into 11 g of an OTA aqueous solution having a solid content of 30% obtained in step (2), and after stirring evenly at room temperature, 5 g of glycerol triglycidyl ether (GTE) was added, and stirring was continued at room temperature until a viscous liquid was formed to obtain a viscous liquid and an aqueous phase. The obtained viscous liquid was separated to obtain a biomass super strong all-purpose adhesive (ATG adhesive).

[0060] The reaction process of preparing aminated cellulose from microcrystalline cellulose and APTES in step (1) of Example 1 is shown in FIG. Figure 1 .

[0061] The reaction process of preparing oxidized tannin from tannin and hydrogen peroxide in step (2) of Example 1 is shown in FIG. Figure 2 .

[0062] The structural formula of glycerol triglycidyl ether in step (3) of Example 1 is shown in Figure 3 .

[0063] The structural diagram of the biomass super strong universal adhesive prepared in Example 1 is shown in Figure 4 .Depend on Figure 4 It can be seen that the biomass super-strong universal adhesive prepared in Example 1 has a cross-linked network structure consisting of aminated cellulose, oxidized tannin and glycerol triglycidyl ether.

[0064] Example 2

[0065] A method for using a biomass super-strong universal adhesive:

[0066] The ATG adhesive prepared in Example 1 was 2 / g of coating amount was evenly applied on one side of the surface of two stainless steel substrates with a specification of 20mm×20mm to form a bonding area, and then the bonding areas of the two stainless steel substrates were overlapped and heated and cured at 120°C for 0.5h to complete the bonding of the substrates and obtain overlapping specimens.

[0067] Example 3

[0068] The difference from Example 2 is that the curing is carried out at room temperature for 72 hours, and the rest is the same as Example 2.

[0069] Example 4

[0070] The difference from Example 2 is that the curing is carried out at room temperature for 240 hours, and the rest is the same as Example 2.

[0071] Example 5

[0072] The difference from Example 2 is that the two stainless steel substrates are replaced by two wood substrates, and the rest are the same as Example 2.

[0073] Example 6

[0074] The difference from Example 2 is that the two stainless steel substrates are replaced by two pieces of glass, and the rest are the same as Example 2.

[0075] Example 7

[0076] The difference from Example 2 is that the two stainless steel substrates are replaced by two copper pieces, and the rest are the same as Example 2.

[0077] Example 8

[0078] The difference from Example 2 is that the two stainless steel substrates are replaced by two bamboo substrates, and the rest are the same as Example 2.

[0079] Comparative Example 1

[0080] A preparation method of TG adhesive:

[0081] (1) Disperse 3.4 g of tannin in 7.9 g of water, then add 0.5 g of hydrogen peroxide and stir at room temperature for 10 min to obtain an amber-colored, homogeneous, transparent liquid, which is the oxidized tannin (OTA) aqueous solution;

[0082] (2) 5 g of glycerol triglycidyl ether (GTE) was added to 11 g of the OTA aqueous solution with a solid content of 30% obtained in step (1), and stirred at room temperature until a viscous liquid was formed to obtain a viscous liquid and an aqueous phase. The obtained viscous liquid was separated to obtain a TG adhesive.

[0083] Comparative Examples 2-8

[0084] The difference from Example 2-8 is that the ATG adhesive prepared in Example 1 is replaced by the TG adhesive prepared in Comparative Example 1, and the other steps and parameters are the same as those of Example 2-8.

[0085] Comparative Example 9

[0086] A preparation method of AG adhesive:

[0087] (1) 20 g of microcrystalline cellulose and 18 g of APTES were dispersed in 100 g of water, stirred at room temperature for 24 h, filtered, rinsed with deionized water, and then dried in an oven at 80 °C to obtain aminated cellulose (AC);

[0088] (2) 3 g of AC obtained in step (1) and 5 g of glycerol triglycidyl ether (GTE) were dispersed in water and stirred at room temperature until a viscous liquid was formed to obtain a viscous liquid and an aqueous phase. The obtained viscous liquid was separated to obtain an AG adhesive.

[0089] Comparative Examples 10-16

[0090] The difference from Example 2-8 is that the ATG adhesive prepared in Example 1 is replaced by the AG adhesive prepared in Comparative Example 9, and the other steps and parameters are the same as those of Examples 2-8.

[0091] The lap shear strength of the lap specimens obtained in Examples 2-8, Comparative Examples 2-8, and Comparative Examples 10-16 were tested with reference to GB / T 17657-2022 “Test methods for physical and chemical properties of wood-based panels and veneered wood-based panels”. The results are shown in Table 1.

[0092] Table 1 Lap shear strength of lap joint specimens obtained from Examples 2-8, Comparative Examples 2-8 and Comparative Examples 10-16

[0093] Overlap test piece Lap shear strength (MPa) Example 2 37.11 Example 3 9.66 Example 4 13.28 Example 5 18.22 Example 6 25.21 Example 7 31.14 Example 8 22.71 Comparative Example 2 19.58 Comparative Example 3 0.89 Comparative Example 4 1.33 Comparative Example 5 15.92 Comparative Example 6 17.61 Comparative Example 7 15.85 Comparative Example 8 19.44 Comparative Example 10 / Comparative Example 11 / Comparative Example 12 / Comparative Example 13 1.26 Comparative Example 14 / Comparative Example 15 / Comparative Example 16 1.29

[0094] In the table, “ / ” indicates that the two substrates cannot be bonded.

[0095] The overlapped specimens obtained in Example 2 and Comparative Example 2 were immersed in water, dichloromethane, and 0.1 mol / L hydrochloric acid for 30 days, respectively. The overlapped shear strength of the overlapped specimens was tested with reference to GB / T17657-2022 "Test methods for physical and chemical properties of wood-based panels and veneered wood-based panels". The results are shown in Table 2.

[0096] Table 2 Lap shear strength of the lap joint specimens obtained in Example 2 and Comparative Example 2 after immersion in water, dichloromethane and 0.1 mol / L hydrochloric acid for 30 days

[0097] Lap shear strength (MPa) Example 2 water 14.70 dichloromethane 12.03 0.1 mol / L hydrochloric acid 8.75 Comparative Example 2 water / dichloromethane / 0.1 mol / L hydrochloric acid /

[0098] In the table, “ / ” means that after 30 days of immersion, the two substrates separated and the lap shear strength could not be tested.

[0099] As can be seen from Table 1, under room temperature conditions, as the curing time increases from 72h (Example 3) to 240h (Example 4), the bonding performance also increases, indicating that the curing time affects the bonding performance. Examples 5-8 explore the bonding performance of the ATG adhesive prepared in Example 1 on different substrates. It can be seen that the ATG adhesive can be bonded to different substrates. As can be seen from Table 2, the ATG adhesive prepared in Example 1 is tolerant to a variety of solvents, including organic solvents, inorganic solvents and strong acids, while the TG adhesive prepared in Comparative Example 1 is not tolerant to organic solvents, inorganic solvents and strong acids.

[0100] The comparison between the examples and the comparative examples illustrates the influence of the adhesive components on the bonding performance. The ATG adhesive prepared in Example 1 has multiple forces, thus generating a stronger cohesive force and excellent bonding performance; while the TG adhesive prepared in Comparative Example 1 has a single force, thus the cohesive force is relatively weak and the bonding performance deteriorates.

[0101] In summary, the ATG adhesive provided by the present invention has the best bonding effect, can achieve bonding to a variety of substrates, and has a certain solvent resistance. In addition, under different requirements, the appropriate curing temperature (room temperature or heating) and curing time can be selected.

[0102] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a biomass super-strong universal adhesive, characterized in that: The following steps are involved: The aminated cellulose is dispersed in an oxidized tannin aqueous solution, homogenized, and then glycerol triglycidyl ether is added, and the mixture is stirred to obtain a viscous liquid and an aqueous phase, and the viscous liquid is separated to obtain the biomass super-strong universal adhesive; The mass ratio of the aminated cellulose, the oxidized tannin aqueous solution and the glycerol triglycidyl ether is 3:11:(3-5); The aminated cellulose is obtained by reacting microcrystalline cellulose and aminopropyltriethoxysilane; the mass ratio of the microcrystalline cellulose to aminopropyltriethoxysilane is 20:18; The oxidized tannin aqueous solution is obtained by reacting hydrogen peroxide with a tannin aqueous solution; the mass ratio of tannin in the hydrogen peroxide and tannin aqueous solution is 0.5:3.4; and the solid content of the oxidized tannin aqueous solution is 20-40%.

2. The biomass super-strong multi-purpose adhesive prepared by the preparation method according to claim 1.

3. The method for using the biomass super-strong universal adhesive according to claim 2, characterized in that: The following steps are involved: Different substrates are overlapped by using the biomass super-strong universal adhesive, and the bonding of the different substrates is completed by curing at room temperature or heating.

4. The method for using the biomass super-strong universal adhesive according to claim 3, characterized in that: The room temperature curing time is 72 to 240 hours.

5. The method for using the biomass super-strong universal adhesive according to claim 3, characterized in that: The temperature of the heating curing is 60-120° C., and the time is 0.5-1 hour.

6. The method for using the biomass super-strong universal adhesive according to claim 3, characterized in that: The substrate includes one or more of wood, bamboo, stainless steel, aluminum, iron, copper, glass, marble, artificial quartz stone, zirconium oxide, and cloth.

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