Recyclable adhesive suitable for bonding of different base materials as well as preparation method and application of recyclable adhesive

Abstract

The invention discloses a recoverable adhesive suitable for bonding of different base materials and a preparation method and application thereof, and relates to the technical field of adhesives. The recyclable adhesive is prepared from the following components in parts by weight: 20 to 40 parts of polyamine monomer, 3 to 8 parts of diisothiocyanate monomer and 3 to 8 parts of modified tannic acid. The preparation method comprises the following steps: preparing modified tannic acid; the preparation method comprises the following steps: mixing diisothiocyanate and a polyamine monomer to generate an isothiocyanate group terminated prepolymer; and mixing the modified tannic acid and the isothiocyanate-terminated prepolymer, and carrying out covalent crosslinking through a Michael addition reaction, so as to prepare the recoverable adhesive.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and more specifically, to a recyclable adhesive applicable to the bonding of different substrates, its preparation method and application. Background Art

[0002] Wood adhesives play an increasingly important role in the fields of wood processing, furniture manufacturing and construction. The main wood adhesives on the market include urea formaldehyde (UF), phenolic formaldehyde (PF) and melamine formaldehyde (MF) adhesives. Although these adhesives have good performance, there are some problems, such as non-renewable raw materials, release of harmful substances such as formaldehyde, etc. Therefore, people have begun to turn to the development of biomass-based adhesives.

[0003] Biomass-based adhesives use renewable biomass resources, such as cellulose, tannin, lignin, soy protein and tannic acid. Among them, tannic acid is regarded as a substitute for traditional formaldehyde-based adhesives due to its biocompatibility, degradability and film-forming ability. However, the high brittleness and low water resistance of tannic acid limit its application. To solve these problems, researchers have adopted various methods, such as adding plasticizers, crosslinking modification and constructing branched structures. Using dendrimers as crosslinking agents can improve the bonding performance and water resistance of tannic acid-based adhesives, but may increase brittleness. Hyperbranched adhesives, especially polyamides, can effectively enhance the toughness of thermosetting resins due to their unique structures and properties. Diisocyanate monomers can improve the bonding strength due to the introduction of a rigid aromatic ring structure.

[0004] Currently, there is a lack of a safe, environmentally friendly biomass recyclable adhesive and its preparation method Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects or deficiencies in the prior art, such as a relatively high temperature for the bonding substrate and the release of a large amount of formaldehyde; to provide a recyclable biomass adhesive. The adhesive provided by the present invention contains characteristic dynamic reversible thiourea bond units, which endow the adhesive with the performance of being dissolved and recycled by solvents, thereby enhancing the use stability of the material and extending the service life.

[0006] Another object of the present invention is to provide a preparation method of the above-mentioned recyclable biomass adhesive.

[0007] Another object of the present invention is to provide a preparation method of the above-mentioned modified tannin recyclable adhesive.

[0008] Another object of the present invention is to provide the application of the above-mentioned adhesive in recyclable biomass adhesives.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A recyclable adhesive applicable to the bonding of different substrates, comprising the following components by weight:

[0011] 20 - 40 parts of polyamine monomer, 3 - 8 parts of diisocyanate monomer, 3 - 8 parts of modified tannic acid.

[0012] Preferably, the modified tannic acid is prepared by the following method:

[0013] Take 1 - 10 parts of tannic acid, add 1.2 - 15 parts of 4 - dimethylaminopyridine and 3.6 - 50 parts of acrylic anhydride, put them into a flask, place the flask in an ultrasonic water bath with a power of 60 - 80 W, and stir at 300 - 500 r / min at 60 - 90 °C for 12 - 24 h; after the reaction is completed, cool the flask to room temperature, and wash the mixture successively with ethyl acetate, 0.5 mol / L NaOH, saturated NaHCO 3 solution and water, and dry it under vacuum to obtain the modified tannic acid.

[0014] Preferably, the polyamine monomer includes: polyamide 651, polyamide 650.

[0015] The preparation method of the above - mentioned recyclable adhesive for bonding different substrates includes the following steps:

[0016] (1) Prepare modified tannic acid;

[0017] (2) Mix the diisocyanate and the polyamine monomer to generate an isocyanate - terminated prepolymer;

[0018] (3) Mix 3 - 8 parts of modified tannic acid and 3 - 8 parts of isocyanate - terminated prepolymer, and carry out covalent cross - linking through Michael addition reaction to obtain the recyclable adhesive.

[0019] Preferably, step (2) specifically includes: take 20 - 40 parts of polyamine monomer, put it into a flask, add 5 - 20 parts of N - N dimethylformamide and stir at room temperature until fully dissolved to obtain a polyamine monomer solution, take 3 - 8 parts of diisocyanate and dissolve it in 5 - 20 parts of N - N dimethylformamide to obtain a diisocyanate solution, slowly drip the diisocyanate solution into the polyamine monomer solution with a constant pressure funnel and stir at 60 - 100 °C for 6 - 12 h to obtain the isocyanate - terminated prepolymer.

[0020] Preferably, the covalent cross - linking in step (3) is as follows:

[0021] Mix the modified tannic acid and the isocyanate - terminated prepolymer, then add 1,8 - diazabicyclo[5.4.0]undec - 7 - ene, and carry out Michael addition reaction;

[0022] Among them, the C=C double bond of modified tannic acid and the -NH of the thiocyanate-terminated prepolymer 4 undergo a Michael addition reaction.

[0023] Apply the above recyclable adhesives suitable for bonding different substrates to the surfaces of different substrates;

[0024] Among them, the substrates include: wood, bamboo, metal, polytetrafluoroethylene, polyvinyl chloride, plexiglass or inorganic glass;

[0025] The wood includes: beech wood and poplar wood;

[0026] The metal includes steel, aluminum or copper.

[0027] Apply the recyclable adhesive to the substrate surface, hot press at 60°C - 100°C for 600 - 6000 seconds, and then place it at room temperature for 12 - 24 hours to eliminate internal stress.

[0028] After use, scrape off the recyclable adhesive adhered to the substrate, dissolve it in N-N dimethylformamide, and regenerate the adhesive at 60 - 100°C to continue bonding the substrate.

[0029] From the above technical solutions, it can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0030] Compared with most adhesives on the market, it can complete bonding at a relatively lower temperature, reducing energy consumption. At the same time, it can be recycled, increasing the usability of the adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0032] Figure 1 It is the mechanism diagram of the modified tannin of the present invention.

[0033] Figure 2 It is the strength diagram of the present invention for overlapping different substrates.

[0034] Figure 3 It is the stress-strain diagram of the present invention for overlapping different substrates in steps.

[0035] Figure 4 It is the infrared spectrum diagram of the present invention for preparing modified tannic acid TM and the preparation raw materials.

[0036] Figure 5This is the infrared spectrum of the isothiocyanate group-terminated prepolymer TD prepared in the present invention. Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] The embodiment of the present invention discloses a high-performance biomass-based recyclable adhesive, and the preparation method includes:

[0039] (1) Prepare modified tannic acid: Take 1-10 parts of tannic acid, add 1.2-15 parts of 4-dimethylaminopyridine and 3.6-50 parts of acrylic anhydride, put them into a flask, place the flask in an ultrasonic water bath with a power of 60-80 W, and stir at 300-500 r / min at 60-90 °C for 12-24 h; after the reaction is completed, cool the flask to room temperature, and wash the mixture with ethyl acetate, 0.5 mol / L NaOH, saturated NaHCO 3 solution and water in sequence, and dry it under vacuum to obtain the modified tannic acid;

[0040] (2) Take 20-40 parts of polyamine monomer, put it into a flask, add 5-20 parts of N-N dimethylformamide and stir at room temperature until it is fully dissolved to obtain a polyamine monomer solution. Take 3-8 parts of diisocyanate and dissolve it in 5-20 parts of N-N dimethylformamide to obtain a diisocyanate solution. Slowly drop the diisocyanate solution into the polyamine monomer solution with a constant pressure funnel and stir at 60-100 °C for 6-12 h to obtain the isothiocyanate group-terminated prepolymer;

[0041] (3) Mix 3-8 parts of modified tannic acid and 3-8 parts of isothiocyanate group-terminated prepolymer, and then add DUB catalyst to carry out covalent crosslinking through Michael addition reaction to prepare a recyclable adhesive.

[0042] Next, the technical solutions provided by the present invention will be described in detail in conjunction with the embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0043] The number of parts in the following embodiments are all parts by mass.

[0044] Example 1

[0045] This example provides a high-performance biomass-based recyclable adhesive (referred to as adhesive for short, the same below), and its preparation process is as follows:

[0046] (1) Under a nitrogen atmosphere, 30 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant pressure funnel and stirred at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0047] (2) 5 parts of the isocyanate group-terminated prepolymer were taken, then 0.7 part of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction was carried out for 12 h. The excess DMF was removed by rotary evaporation of the reaction product to obtain a viscous high-performance biomass-based recyclable adhesive. Wood was bonded and hot-pressed at 80 °C for 90 min. The adhesive was dissolved and re-bonded to prepare a new specimen, and part of the mechanical strength could be restored. The bonding strength results before and after recycling of the adhesive are shown in Table 1 respectively.

[0048] Example 2

[0049] This example provides a high-performance biomass-based recyclable adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0050] (1) Under a nitrogen atmosphere, 30 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 3 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant pressure funnel and stirred at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0051] (2) 5 parts of the isocyanate group-terminated prepolymer were taken, then 0.7 part of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction was carried out for 12 h. The excess DMF was removed by rotary evaporation of the reaction product to obtain a viscous high-performance biomass-based recyclable adhesive. Wood was bonded and hot-pressed at 80 °C for 90 min. The adhesive was dissolved and re-bonded to prepare a new specimen, and part of the mechanical strength could be restored. The bonding strength results before and after recycling of the adhesive are shown in Table 1 respectively.

[0052] Example 3

[0053] This example provides a high-performance biomass-based recyclable adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0054] (1) Under a nitrogen atmosphere, take 30 parts of polyamide 651, put it into a flask, add 10 parts of N,N-dimethylformamide, stir at room temperature until fully dissolved, take 8 parts of diisocyanate and dissolve it in 10 parts of N,N-dimethylformamide, slowly add the dissolved diisocyanate dropwise using a constant pressure funnel and stir at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0055] (2) Take 5 parts of the isocyanate group-terminated prepolymer, then add 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid, react for 12 h, perform rotary evaporation on the reaction product to remove the excess DMF, obtain a viscous high-performance biomass-based recyclable adhesive, bond wood and hot press at 80 °C for 90 min. The adhesive can be redissolved and re-bonded to prepare a new sample, and partial mechanical strength can be restored. The bonding strength results of the adhesive before and after recycling are shown in Table 1 respectively.

[0056] Example 4

[0057] This example provides a high-performance biomass-based recyclable adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0058] (1) Under a nitrogen atmosphere, take 30 parts of polyamide 651, put it into a flask, add 10 parts of N,N-dimethylformamide, stir at room temperature until fully dissolved, take 5 parts of diisocyanate and dissolve it in 10 parts of N,N-dimethylformamide, slowly add the dissolved diisocyanate dropwise using a constant pressure funnel and stir at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0059] (2) Take 5 parts of the isocyanate group-terminated prepolymer, then add 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 3 parts of modified tannic acid, react for 12 h, perform rotary evaporation on the reaction product to remove the excess DMF, obtain a viscous high-performance biomass-based recyclable adhesive, bond wood and hot press at 80 °C for 90 min. The adhesive can be redissolved and re-bonded to prepare a new sample, and partial mechanical strength can be restored. The bonding strength results of the adhesive before and after recycling are shown in Table 1 respectively.

[0060] Example 5

[0061] This example provides a high-performance biomass-based recyclable adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0062] (1) Under a nitrogen atmosphere, take 30 parts of polyamide 651, put it into a flask, add 10 parts of N,N-dimethylformamide, stir at room temperature until fully dissolved, take 5 parts of diisocyanate and dissolve it in 10 parts of N,N-dimethylformamide, slowly add the dissolved diisocyanate dropwise using a constant pressure funnel and stir at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0063] (2) Take 5 parts of the isocyanate group-terminated prepolymer, then add 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 8 parts of modified tannic acid, react for 12 h, perform rotary evaporation on the reaction product to remove the excess DMF, obtain a viscous high-performance biomass-based recyclable adhesive, bond wood and hot press at 80 °C for 90 min. The adhesive can be redissolved and re-bonded to prepare a new sample, and part of the mechanical strength can be restored. The bonding strength results before and after adhesive recycling are shown in Table 1 respectively.

[0064] Example 6

[0065] This example provides a high-performance biomass-based recyclable adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0066] (1) Under a nitrogen atmosphere, take 20 parts of polyamide 651, put it into a flask, add 10 parts of N,N-dimethylformamide, stir at room temperature until fully dissolved, take 5 parts of diisocyanate and dissolve it in 10 parts of N,N-dimethylformamide, slowly add the dissolved diisocyanate dropwise using a constant pressure funnel and stir at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0067] (2) Take 5 parts of the isocyanate group-terminated prepolymer, then add 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid, react for 12 h, perform rotary evaporation on the reaction product to remove the excess DMF, obtain a viscous high-performance biomass-based recyclable adhesive, bond wood and hot press at 80 °C for 90 min. The adhesive can be redissolved and re-bonded to prepare a new sample, and part of the mechanical strength can be restored. The bonding strength results before and after adhesive recycling are shown in Table 1 respectively.

[0068] Example 7

[0069] This example provides a high-performance biomass-based recyclable adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0070] (1) Under a nitrogen atmosphere, 40 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant pressure funnel and stirred at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0071] (2) 5 parts of the isocyanate group-terminated prepolymer were taken, then 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction was carried out for 12 h. The excess DMF was removed from the reaction product by rotary evaporation to obtain a viscous high-performance biomass-based recyclable adhesive, which was used to bond wood and hot-pressed at 80 °C for 90 min. The adhesive was redissolved and re-bonded to prepare a new specimen, and part of the mechanical strength could be restored. The bonding strength results before and after adhesive recycling are shown in Table 1 respectively.

[0072] Example 8

[0073] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0074] (1) Under a nitrogen atmosphere, 30 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant pressure funnel and stirred at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0075] (2) 5 parts of the isocyanate group-terminated prepolymer were taken, then 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction was carried out for 12 h. The excess DMF was removed from the reaction product by rotary evaporation to obtain a viscous high-performance biomass-based recyclable adhesive, which was used to bond wood and hot-pressed at room temperature for 24 h. The adhesive was redissolved and re-bonded to prepare a new specimen, and part of the mechanical strength could be restored. The bonding strength results before and after adhesive recycling are shown in Table 1 respectively.

[0076] Example 9

[0077] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0078] (1) Under a nitrogen atmosphere, take 30 parts of polyamide 651, put it into a flask, add 10 parts of N,N-dimethylformamide, stir at room temperature until fully dissolved. Take 5 parts of diisocyanate and dissolve it in 10 parts of N,N-dimethylformamide. Slowly add the dissolved diisocyanate dropwise using a constant pressure funnel and stir at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0079] (2) Take 5 parts of the isocyanate group-terminated prepolymer, then add 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid, react for 12 h. Perform rotary evaporation on the reaction product to remove the excess DMF, obtaining a viscous high-performance biomass-based recyclable adhesive. Bond wood and hot press at 60 °C for 90 min. The adhesive can be redissolved and re-bonded to prepare a new specimen, and partial mechanical strength can be restored. The bonding strength results before and after adhesive recycling are shown in Table 1 respectively.

[0080] Example 10

[0081] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0082] (1) Under a nitrogen atmosphere, take 30 parts of polyamide 651, put it into a flask, add 10 parts of N,N-dimethylformamide, stir at room temperature until fully dissolved. Take 5 parts of diisocyanate and dissolve it in 10 parts of N,N-dimethylformamide. Slowly add the dissolved diisocyanate dropwise using a constant pressure funnel and stir at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0083] (2) Take 5 parts of the isocyanate group-terminated prepolymer, then add 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid, react for 12 h. Perform rotary evaporation on the reaction product to remove the excess DMF, obtaining a viscous high-performance biomass-based recyclable adhesive. Bond wood and hot press at 100 °C for 90 min. The adhesive can be redissolved and re-bonded to prepare a new specimen, and partial mechanical strength can be restored. The bonding strength results before and after adhesive recycling are shown in Table 1 respectively.

[0084] Example 11

[0085] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0086] (1) Under a nitrogen atmosphere, 30 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant pressure funnel and stirred at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0087] (2) 5 parts of the isocyanate group-terminated prepolymer were taken, then 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction was carried out for 12 h. The reaction product was rotary evaporated to remove the excess DMF, and a viscous high-performance biomass-based recyclable adhesive was obtained. Bamboo was bonded and hot-pressed at 80 °C for 90 min. The adhesive was dissolved and re-bonded to prepare a new specimen, and part of the mechanical strength could be restored. The bonding strength results before and after adhesive recycling are shown in Table 1 respectively.

[0088] Example 12

[0089] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0090] (1) Under a nitrogen atmosphere, 30 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant pressure funnel and stirred at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0091] (2) 5 parts of the isocyanate group-terminated prepolymer were taken, then 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction was carried out for 12 h. The reaction product was rotary evaporated to remove the excess DMF, and a viscous high-performance biomass-based recyclable adhesive was obtained. Stainless steel was bonded and hot-pressed at 80 °C for 90 min. The adhesive was dissolved and re-bonded to prepare a new specimen, and part of the mechanical strength could be restored. The bonding strength results before and after adhesive recycling are shown in Table 1 respectively.

[0092] Example 13

[0093] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0094] (1) Under a nitrogen atmosphere, 30 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant-pressure funnel and stirred at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0095] (2) 5 parts of the isocyanate group-terminated prepolymer were taken, then 0.7 part of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction was carried out for 12 h. The reaction product was rotary evaporated to remove the excess DMF, and a viscous high-performance biomass-based recyclable adhesive was obtained. The aluminum substrate was bonded and hot-pressed at 80 °C for 90 min. The adhesive was dissolved and re-bonded to prepare a new specimen, and part of the mechanical strength could be restored. The bonding strength results before and after the recycling of the adhesive are shown in Table 1 respectively.

[0096] Example 14

[0097] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0098] (1) Under a nitrogen atmosphere, 30 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant-pressure funnel and stirred at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0099] (2) 5 parts of the isocyanate group-terminated prepolymer were taken, then 0.7 part of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction was carried out for 12 h. The reaction product was rotary evaporated to remove the excess DMF, and a viscous high-performance biomass-based recyclable adhesive was obtained. The copper substrate was bonded and hot-pressed at 80 °C for 90 min. The adhesive was dissolved and re-bonded to prepare a new specimen, and part of the mechanical strength could be restored. The bonding strength results before and after the recycling of the adhesive are shown in Table 1 respectively.

[0100] Example 15

[0101] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0102] (1) Under a nitrogen atmosphere, 30 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant-pressure funnel and stirred at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0103] (2) 5 parts of the isocyanate group-terminated prepolymer were taken, then 0.7 part of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction was carried out for 12 h. The excess DMF was removed from the reaction product by rotary evaporation to obtain a viscous high-performance biomass-based recyclable adhesive. PVC was bonded and hot-pressed at 80 °C for 90 min. The adhesive was redissolved and re-bonded to prepare a new sample, and part of the mechanical strength could be restored. The adhesive strength results before and after recycling are shown in Table 1 respectively.

[0104] Example 16

[0105] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0106] (1) Under a nitrogen atmosphere, 30 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant-pressure funnel and stirred at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0107] (2) 5 parts of the isocyanate group-terminated prepolymer were taken, then 0.7 part of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction was carried out for 12 h. The excess DMF was removed from the reaction product by rotary evaporation to obtain a viscous high-performance biomass-based recyclable adhesive. PTFE was bonded and hot-pressed at 80 °C for 90 min. The adhesive was redissolved and re-bonded to prepare a new sample, and part of the mechanical strength could be restored. The adhesive strength results before and after recycling are shown in Table 1 respectively.

[0108] Example 17

[0109] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0110] (1) Under a nitrogen atmosphere, take 30 parts of polyamide 651, put it into a flask, add 10 parts of N,N-dimethylformamide, stir at room temperature until fully dissolved, take 5 parts of diisocyanate and dissolve it in 10 parts of N,N-dimethylformamide, slowly drip the dissolved diisocyanate with a constant pressure funnel and stir at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0111] (2) Take 5 parts of the isocyanate group-terminated prepolymer, then add 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid, react for 12 h, perform rotary evaporation on the reaction product to remove the excess DMF, obtain a viscous high-performance biomass-based recyclable adhesive, bond organic glass and hot press at 80 °C for 90 min. The adhesive can be redissolved and re-bonded to prepare a new sample, and partial mechanical strength can be restored. The adhesive strength results before and after recycling are shown in Table 1 respectively.

[0112] Example 18

[0113] This example provides a high-performance biomass-based adhesive (hereinafter referred to as adhesive for short), and its preparation process is as follows:

[0114] (1) Under a nitrogen atmosphere, take 30 parts of polyamide 651, put it into a flask, add 10 parts of N,N-dimethylformamide, stir at room temperature until fully dissolved, take 5 parts of diisocyanate and dissolve it in 10 parts of N,N-dimethylformamide, slowly drip the dissolved diisocyanate with a constant pressure funnel and stir at 60 °C for 6 h to obtain an isocyanate group-terminated prepolymer;

[0115] (2) Take 5 parts of the isocyanate group-terminated prepolymer, then add 0.7 parts of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid, react for 12 h, perform rotary evaporation on the reaction product to remove the excess DMF, obtain a viscous high-performance biomass-based recyclable adhesive, bond inorganic glass and hot press at 80 °C for 90 min. The adhesive can be redissolved and re-bonded to prepare a new sample, and partial mechanical strength can be restored. The adhesive strength results before and after recycling are shown in Table 1 respectively.

[0116] Comparative Example 1

[0117] This example provides a high-performance biomass-based adhesive (hereinafter referred to as adhesive for short), and its preparation process is as follows.

[0118] Under a nitrogen atmosphere, 30 parts of polyamide 650 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant-pressure funnel and stirred at 60 °C for 6 h. Then, 0.7 part of 1,8-diazabicyclo[5.4.0]undec-7-ene DUB catalyst and 5 parts of modified tannic acid were added, and the reaction continued for 12 h. The reaction product was rotary evaporated to remove the excess DMF, obtaining a viscous high-performance biomass-based recyclable adhesive. The adhesive was used to bond wood and hot-pressed at 80 °C for 90 min. The adhesive was dissolved and re-bonded to prepare a new specimen, and part of the mechanical strength could be restored. The adhesive strength results before and after recycling are shown in Table 1 respectively.

[0119] Comparative Example 2

[0120] This example provides a high-performance biomass-based adhesive (referred to as adhesive, the same below), and its preparation process is as follows:

[0121] Under a nitrogen atmosphere, 30 parts of polyamide 651 were taken and placed in a flask. 10 parts of N,N-dimethylformamide were added and stirred at room temperature until completely dissolved. 5 parts of diisocyanate were dissolved in 10 parts of N,N-dimethylformamide, and the dissolved diisocyanate was slowly added dropwise using a constant-pressure funnel and stirred at 60 °C for 6 h. Then, 5 parts of modified tannic acid TM were added, and the reaction continued for 12 h. The reaction product was rotary evaporated to remove the excess DMF, obtaining a viscous high-performance biomass-based recyclable adhesive. The adhesive was used to bond wood and hot-pressed at 80 °C for 90 min. The adhesive was dissolved and re-bonded to prepare a new specimen, and part of the mechanical strength could be restored. The adhesive strength results before and after recycling are shown in Table 1 respectively.

[0122] Table 1

[0123]

[0124]

[0125] As can be seen from the table, the prepared adhesive has stronger bonding performance for wood and bamboo. The adhesive can penetrate into the internal pores of wood and bamboo to form mechanical interlocking. At the same time, the bonding to polytetrafluoroethylene is also stronger than that of most adhesives on the market. This is because the primary amine (—NH 2 ) in the polyamine molecule has "extra" hydrogen atoms, and these hydrogen atoms can form coordination bonds with the multi-electron structure of polytetrafluoroethylene, thus achieving adhesion. In contrast, secondary amines and tertiary amines do not have extra hydrogen atoms and therefore cannot form coordination bonds with polytetrafluoroethylene. Due to the introduction of reversible dynamic bonds, the recycling effect of the adhesive is greatly improved, increasing the practicality of the experiment and greatly reducing the cost.

[0126] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple. For related parts, reference can be made to the description in the method section.

[0127] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A recyclable adhesive suitable for bonding different substrates, characterized in that: The invention comprises the following components in parts by weight: 20-40 parts of polyamine monomer, 3-8 parts of diisothiocyanate monomer and 3-8 parts of modified tannic acid.

2. A recyclable adhesive suitable for bonding different substrates according to claim 1, characterized in that: The modified tannic acid is prepared by the following method: Take 1-10 parts of tannic acid, add 1.2-15 parts of 4-dimethylaminopyridine and 3.6-50 parts of acrylic anhydride, put them into a flask, place the flask in an ultrasonic water bath with a power of 60-80W, and stir at 300-500r / min at 60-90°C for 12-24h; after the reaction is completed, cool the flask to room temperature, wash the mixture with ethyl acetate, 0.5mol / LNaOH, saturated NaHCO3 solution and water in turn, and dry under vacuum to obtain the modified tannic acid.

3. The recyclable adhesive suitable for bonding different substrates according to claim 1, characterized in that: The polyamine monomer includes: polyamide 651 or polyamide 650.

4. A method for preparing a recyclable adhesive suitable for bonding different substrates, characterized in that: The following steps are involved: (1) preparing modified tannic acid; (2) mixing diisothiocyanate and polyamine monomers to form an isothiocyanate-terminated prepolymer; (3) 3-8 parts of modified tannic acid and 3-8 parts of isothiocyanate-terminated prepolymer are mixed and covalently cross-linked by Michael addition reaction to prepare a recyclable adhesive.

5. The method for preparing a recyclable adhesive suitable for bonding different substrates according to claim 4, characterized in that: Step (2) specifically comprises: taking 20-40 parts of a polyamine monomer, putting it into a flask, adding 5-20 parts of N-N-dimethylformamide and stirring at room temperature until it is fully dissolved to obtain a polyamine monomer solution, taking 3-8 parts of diisothiocyanate and dissolving it in 5-20 parts of N-N-dimethylformamide to obtain a diisothiocyanate solution, slowly adding the diisothiocyanate solution to the polyamine monomer solution with a constant pressure funnel and stirring at 60-100° C. for 6-12 hours to obtain the isothiocyanate-terminated prepolymer.

6. The method for preparing a recyclable adhesive suitable for bonding different substrates according to claim 4, characterized in that: The covalent cross-linking in step (3) is: The modified tannic acid and the isothiocyanate-terminated prepolymer are mixed, and then 1,8-diazabicyclo[5.4.0]undec-7-ene is added to carry out a Michael addition reaction.

7. Use of the recyclable adhesive suitable for bonding different substrates as described in any one of claims 1 to 3 or the recyclable adhesive suitable for bonding different substrates obtained by the preparation method according to any one of claims 4 to 6 in bonding different substrate surfaces.

8. The use according to claim 7, characterized in that: The substrate includes: wood, bamboo, metal, polytetrafluoroethylene, polyvinyl chloride, organic glass or inorganic glass; The wood includes beech and poplar; The metal includes steel, aluminum or copper.

9. The use according to claim 8, characterized in that: The recyclable adhesive is applied to the surface of a substrate, hot-pressed at 60° C.-100° C. for 600-6000 seconds, and then left at room temperature for 12-24 hours to eliminate internal stress.

10. The use according to claim 9, characterized in that: After use, the recyclable adhesive bonded to the substrate is scraped off, dissolved in NN dimethylformamide, and regenerated into adhesive at 60-100°C to continue bonding the substrate.

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