Intelligent responsive adhesive, method for preparing the same and use thereof

Abstract

The application discloses an intelligent response adhesive and a preparation method and application thereof. The intelligent response adhesive is composed of an interpenetrating polymer network containing a dynamic reversible bond, and reversibly undergoes a conformational transition of "adhesion-slippage" triggered by temperature. The intelligent response adhesive provided by the application presents an extended "adhesion conformation" of the adhesive molecular chain under room temperature conditions, and the molecular chain reversibly folds when heated to a trigger temperature, so that the adhesive molecules are transformed into a dense "slippage conformation", and the viscosity is reduced, thereby realizing zero-residue peeling. After cooling, the molecular chain can recover to the extended state, thereby realizing the repeated use of the intelligent response adhesive. Meanwhile, the intelligent response adhesive is used for preparing a tape product, and a heat-sensitive layer is formed on the surface of the tape, which can change color at the trigger temperature through the thermochromic microcapsules, thereby realizing the visualization of the tape, and realizing the comprehensive use effect of zero residue, repeatability and visualization of the tape product.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of adhesives, and particularly relates to an intelligent response adhesive as well as a preparation method and application thereof. BACKGROUND

[0002] Hot melt adhesive (HMA) is a 100% solid, solvent-free, heated and melted coated, and cooled and solidified adhesive, which is a temperature triggered adhesive with the largest use and the most mature industrialization in the fields of packaging, sanitary materials, automobiles, electronics and woodworking.

[0003] Reversible dynamic bond polyurethane (DPU) is a new generation of smart polyurethane that introduces reversible covalent / non-covalent bonds into the polyurethane backbone or cross-linked network, achieving self-healing, reprocessable, recyclable, and reversible bonding triggered by heat / light / chemical / mechanical processes. It is a current hot research direction in hot melt adhesives. For example, Chinese invention patent CN118638503A discloses a reusable polyurethane hot melt adhesive containing multiple dynamic covalent bonds, its preparation method, and its application. It is obtained through the reaction of polyester polyol, diisocyanate, a small molecule chain extender containing oxime structural units, bismaleimide, and a small molecule chain extender containing furan structural units. The polyurethane hot melt adhesive provided by this invention is more stable than polyoxime-urethane hot melt adhesives and features fast curing speed, high initial bond strength, reusable bonding and disassembly as needed, and excellent heat resistance, solvent resistance, and weather resistance. However, the multiple dynamic bonds it contains require a temperature of 120-140°C during use to ensure that all dynamic bonds can be dissociated. High temperatures can lead to polymer degradation or other side reactions, resulting in incomplete bonding of dynamic bonds when cooling and re-crosslinking, making it difficult to reliably repeat the process and resulting in poor industrial operability. In particular, the presence of multiple dynamic bonds in the polymer makes it easy to generate irreversible crosslinks, which makes it increasingly difficult to debond and reduces the number of times it can be reused. Chinese invention patent CN118496800A discloses a thermally reversible polyurethane adhesive composition, a related bonding method, and bonded articles. The thermally reversible polyurethane adhesive composition comprises a reaction product of a polyfunctional maleimide and a furan-terminated prepolymer. The furan-terminated prepolymer comprises a reaction product of a monofunctional furan and an isocyanate-terminated prepolymer. The isocyanate-terminated prepolymer comprises a reaction product of a diisocyanate and a difunctional oligomer. The difunctional oligomer is (a) end-capped at a first end by an α portion, wherein the α portion is a hydroxyl or amino group, and (b) end-capped at a second end opposite to the first end by an ω portion, wherein the ω portion is a hydroxyl or amino group. The resulting furan-terminated prepolymer has a linear structure. However, further research revealed that the adhesives obtained by reacting polymers, including the furan-terminated prepolymer with a linear structure provided by CN118496800A, with bismaleimide can only achieve partial warm-touch performance in actual use. When warm-touch conditions are reached, the tape softens and peels off, and can be reused after cooling. However, after repeated use, some dynamic bonds (such as DA, disulfide bonds, oxime-carbamates, etc.) break and cannot be completely reassembled. Furthermore, the softened tape interface suffers from micro-defects due to the flow caused by network dissociation. Repeated reuse leads to the accumulation of these micro-defects, resulting in a decrease in the tape's adhesiveness and shear strength.

[0004] Therefore, this invention provides a smart responsive adhesive based on the prior art, which uses a polymer with an interpenetrating network structure containing dynamic reversible covalent bonds to solve the problems existing in the prior art. Summary of the Invention

[0005] The main objective of this invention is to provide a smart responsive adhesive, its preparation method, and its application, in order to overcome the shortcomings of the prior art.

[0006] To achieve the above-mentioned objectives, the present invention employs the technical solution described below.

[0007] As the first objective of the invention, this invention provides a smart responsive adhesive, which uses a furan-terminated polyurethane prepolymer as a diene and a bismaleimide crosslinker as a dienophile, and reacts with the furan groups of the furan-terminated polyurethane prepolymer via a Diels-Alder reaction to form a polymer with an interpenetrating network structure containing dynamic reversible covalent bonds; the smart responsive adhesive undergoes a reversible "adhesion-slip" conformational transition when heated to a trigger temperature.

[0008] In a preferred embodiment, the smart responsive adhesive is a reaction product of furan-terminated polyurethane prepolymer and bismaleimide crosslinking agent.

[0009] In a preferred embodiment, the composition consists of 40-60 parts of furan-terminated polyurethane prepolymer and 5-10 parts of bismaleimide crosslinking agent.

[0010] In a preferred embodiment, the triggering temperature of the smart responsive adhesive is 60~70℃; the interpenetrating network dissociates at 60~70℃, at which point the DA bonds undergo reversible breakage, causing the network to temporarily "soften," which macroscopically manifests as a sharp drop in cohesive strength, achieving "slippage."

[0011] In a preferred embodiment, the smart responsive adhesive also includes a catalyst.

[0012] Preferably, the catalyst is dibutyltin dilaurate or stannous octoate.

[0013] More preferably, the catalyst is dibutyltin dilaurate.

[0014] More preferably, the amount of catalyst added is 0.1 to 1.5 wt% based on furan-terminated polyurethane prepolymer.

[0015] As a second objective of the invention, the present invention also provides a method for preparing the smart responsive adhesive as described above, the specific steps of which include:

[0016] S1. Provide furan-terminated polyurethane prepolymer

[0017] Polyethylene glycol (PEG) was dehydrated at 110-120°C under a vacuum of -0.095 MPa for 2 hours. After cooling to 60°C, diisocyanate was added. Under nitrogen protection, -NCO and -OH reacted at 80-85°C for 3-4 hours to obtain an isocyanate-terminated polyurethane prepolymer. After cooling to 40-50°C, furfuryl alcohol was added. The furfuryl alcohol continued to react with the remaining -NCO for 2-3 hours to obtain furan-terminated polyurethane prepolymer FPPU.

[0018] S2. Add the bismaleimide crosslinking agent to the furan-terminated polyurethane prepolymer and stir for 15-30 minutes at 60-70°C and 200-500 rpm to uniformly disperse the bismaleimide crosslinking agent in the matrix, forming a homogeneous mixture, which is the smart responsive adhesive.

[0019] Preferably, the number average molecular weight of polyethylene glycol (PEG) is 1000-2000.

[0020] Preferably, the molar ratio of -NCO to -OH is 1.2 to 1.5:1.

[0021] Preferably, the molar ratio of furfuryl alcohol to residual -NCO is 1.05~1.1:1.

[0022] Preferably, the number average molecular weight of the furan-terminated polyurethane prepolymer is 3000-8000.

[0023] As a third objective of the invention, the present invention also provides a smart responsive tape having at least a multi-layer structure of a flexible support layer, a smart responsive adhesive layer, and an interface functional layer, wherein the smart responsive adhesive layer is a smart responsive adhesive as described above, and the flexible support layer is a polyurethane containing an elastic network of polyurea bonds.

[0024] In a preferred embodiment, the flexible support layer is a reaction product of hydroxyl-terminated polybutadiene and diisocyanate, forming irreversible polyurethane / polyurea bonds to construct a permanent elastic network. The flexible support layer acts like a "scaffolding" structure to maintain the integrity of the overall adhesive layer structure, ensuring that the responsive network does not completely flow when dissociated and can quickly recover its shape after cooling, thereby avoiding interface defects caused during the dissociation of the interpenetrating network and increasing the number of times the tape can be reused.

[0025] In a preferred embodiment, the mass ratio of hydroxyl-terminated polybutadiene to diisocyanate is 30-40:8-12.

[0026] In a preferred embodiment, the interface functional layer is obtained by coating the surface of the flexible support layer with a low surface energy release resin.

[0027] As a preferred embodiment, it further includes a thermochromic indicator layer; the thermochromic indicator layer is formed by a reversible thermochromic process using thermochromic microcapsules.

[0028] In a preferred embodiment, the core material of the thermochromic microcapsule is a mixture of crystal violet lactone and bisphenol A. The color change temperature during the reaction process is 60°C, and the color changes from red to colorless, providing a direct and accurate indication of the trigger temperature.

[0029] In a preferred embodiment, the flexible support layer further includes thermochromic microcapsules with a core material that is a mixture of crystal violet lactone and bisphenol A.

[0030] As a fourth objective of the invention, the present invention also provides an application of the smart responsive tape described above in automotive interiors and electronic products.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. This invention uses furan-terminated polyurethane prepolymer as a diene and bismaleimide crosslinking agent as a dienophile. Through Diels-Alder reaction, a polymer with an interpenetrating network structure containing dynamic reversible covalent bonds is formed. The polymer undergoes a reversible "adhesion-slip" conformational transition at the trigger temperature. The reversible reaction temperature of the dynamic bonds in the reaction product is low, which allows for precise control of the peeling temperature. After dissociation, the shear strength drops sharply, cohesion fails, and the peeling force curve is steep, thereby achieving clean peeling without residue.

[0033] 2. The reaction products of hydroxyl-terminated polybutadiene and diisocyanate form irreversible polyurethane / polyurea bonds, constructing a permanent elastic network; the flexible support layer acts like a "scaffolding" structure to maintain the integrity of the overall adhesive layer structure, ensuring that the responsive network does not completely flow when dissociated and can quickly recover its shape after cooling, thereby avoiding interface defects caused during the dissociation of the interpenetrating network and increasing the number of times the tape can be reused.

[0034] 4. This invention reduces side reactions during the dissociation process by triggering the dissociation of dynamic bonds at low temperatures, thereby improving the stable repeatability of the tape product.

[0035] 5. This invention provides a visual thermochromic indicator layer on the surface of the tape, which is consistent with the trigger temperature, ensuring precise control of the tape debonding temperature.

[0036] 4. Through the rapid cooling effect of the flexible support layer and the synergistic effect of the interpenetrating network of dynamic bonds, the dependence of the thermal peel tape on the melting effect of the low melting point layer in the prior art is avoided, so that the tape has a stable structure and avoids peel residue. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is the reversible network formation reaction principle provided in Embodiment 1 of the present invention. Detailed Implementation

[0039] Together with Figure 1 The following detailed description will provide a more complete understanding of the invention. Detailed embodiments of the invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary and the invention can be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as intended to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0040] The present invention provides an adhesive composed of an interpenetrating polymer network containing dynamic reversible bonds (such as Diels-Alder adducts), which is temperature-triggered to undergo a reversible "adhesion-slip" conformational transition.

[0041] The adhesive has a protein-like smart responsive structure. At room temperature, the molecular chains exhibit an extended "adhesive conformation," providing high adhesion. When heated to a specific trigger temperature (e.g., 60°C), the molecular chains undergo reversible folding through internal forces, transforming into a dense "glide conformation." This causes the adhesive layer to become macroscopically brittle and its cohesive strength to drop sharply, thereby achieving zero-residue peeling. After cooling, the molecular chains can return to their extended state.

[0042] It is a reaction product containing furan-terminated polyurethane prepolymer FPPU and bismaleimide crosslinking agent.

[0043] The molecular formula of furan-terminated polyurethane prepolymer (FPPU) is:

[0044] Furan-(CH2)2-O-[C(O)-NH-(CH2)6-NH-C(O)-O-(CH2CH2O) n -CH2CH2-O] m -C(O)-NH-(CH2)6-NH-C(O)-O-(CH2)2-Furan, where Furan represents the terminal furan structure.

[0045] See Figure 1This is a schematic diagram of the reaction mechanism of furan-terminated polyurethane prepolymer FPPU and bismaleimide in the adhesive of the present invention. As can be seen from the figure, it forms a reversible network formation reaction through the Diels-Alder reaction, thereby achieving the "thermal activation" function.

[0046] As another aspect of the invention, the present invention provides a heat-activated tape, comprising a flexible support layer, a smart responsive adhesive layer, and a low surface energy release layer in sequence; the smart responsive adhesive layer is composed of an interpenetrating polymer network containing dynamic reversible covalent bonds, which can undergo a reversible conformational transformation at a specific trigger temperature, thereby macroscopically manifesting as a sharp decrease in adhesion.

[0047] The flexible support layer, as an auxiliary functional layer, is a porous flexible polymer film (e.g., polyurethane foam) that impregnates the smart adhesive. It provides mechanical support, and its porous structure ensures sufficient deformation and response space for the adhesive. At the same time, the flexible support layer acts like a "scaffolding" structure to maintain the integrity of the overall adhesive layer structure, ensuring that the responsive network does not flow completely during dissociation and can quickly recover its shape after cooling. This avoids interface defects caused during the dissociation of the interpenetrating network and increases the number of times the tape can be reused.

[0048] The interface functional layer uses a low surface energy release layer, which is coated on one side of the tape (the side opposite to the flexible support layer). Its surface energy is lower than that of the smart adhesive layer, thereby achieving internal peeling. When heated, the adhesive's adhesion to the release layer fails first, guiding peeling to occur at this interface.

[0049] The thermochromic indicator layer, as a sensing feedback layer, can be physically mixed with the flexible support layer or the overall adhesive layer, or it can be coated as an independent thin layer on the surface of the flexible support layer. The thermochromic indicator layer contains thermochromic microcapsules that change color (such as from red to green) at the trigger temperature, realizing a visual effect of temperature change and intuitively indicating that the trigger temperature has been reached. This not only improves the user experience but also enables precise control of the trigger temperature.

[0050] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0051] Example 1

[0052] Step 1: Preparation of furan-terminated polyurethane prepolymer (FPPU)

[0053] 50 g of polyethylene glycol (PEG, Mn=2000) was added to a reactor and dehydrated under vacuum at 110℃ and -0.095 MPa for 2 hours. After cooling to 60℃, 11.2 g of hexamethylene diisocyanate (HDI) was added, and the mixture was reacted at 80℃ for 3 hours under nitrogen protection to obtain an isocyanate-terminated prepolymer. The mixture was then cooled to 45℃, and 3.5 g of furfuryl alcohol was added. The reaction was continued for 2.5 hours to obtain a furan-terminated polyurethane prepolymer (FPPU), with a number average molecular weight of 5200.

[0054] Step 2: Preparation of smart responsive adhesive

[0055] Weigh 50 g of the FPPU prepared in step 1, adjust the pH to 4.5-5.5 with acetic acid, and then add 0.1 g of dibutyltin dilaurate (DBTDL) and 5 g of bismaleimide crosslinking agent (BMI, 1,1'-(methylenedi-4,1-phenylene)bismaleimide, purchased from Aladdin) to the FPPU. Stir at 65℃ and 300 rpm for 20 minutes to obtain the smart responsive adhesive.

[0056] Step 3: Prepare flexible support material

[0057] 35 g of hydroxyl-terminated polybutadiene (HTPB, Mn=2800) was mixed with 8.5 g of toluene diisocyanate (TDI), and 50 g of tetrahydrofuran (THF) and 0.035 g of dibutyltin dilaurate were added. The mixture was stirred at room temperature and pressure for 1 hour to obtain a flexible support material.

[0058] Step 4: Prepare heat-activated tape

[0059] The smart responsive adhesive obtained in step 2 is coated onto the surface of low surface energy release paper (such as Dow Corning™ Syl-Off™ release paper) to a thickness of 50 μm, forming a smart responsive adhesive layer. Then, the flexible support material from step 3 is coated onto the surface of the smart responsive adhesive layer to a thickness of 30 μm, forming a flexible support layer.

[0060] Step 5: Prepare the thermochromic indicator layer

[0061] 3.5 g of crystal violet lactone, 7 g of bisphenol A, and 89.5 g of tetradecyl alcohol were dissolved by heating to prepare a clear ternary color-changing system oil phase. The oil phase was added to water containing 0.8% sodium dodecyl sulfate at 65°C and emulsified at high speed to obtain a thermochromic reversible color-changing emulsion. 8 g of melamine resin prepolymer was added dropwise to the emulsion under heating conditions, and in-situ polymerization was carried out at 85°C for 1 hour to obtain a thermochromic microcapsule suspension. The suspension was coated on the surface of a flexible support layer, and after drying, a thermochromic indicator layer was obtained, ultimately yielding a heat-activated tape.

[0062] Example 2

[0063] The only difference between this embodiment and Example 1 is that in step 1, the amount of bismaleimide crosslinking agent added is 10g; all other steps are the same.

[0064] Example 3

[0065] The only difference between this embodiment and Embodiment 1 is that the amount of furan-terminated polyurethane prepolymer added is 40g; all other steps are the same.

[0066] Example 4

[0067] The only difference between this embodiment and Embodiment 1 is that the amount of furan-terminated polyurethane prepolymer added is 60g; all other steps are the same.

[0068] Example 5

[0069] The difference between this embodiment and Embodiment 1 is that the thermochromic microcapsule suspension prepared in step 4 is added to the smart responsive adhesive in step 2 and the flexible support material in step 3, so that the smart responsive adhesive layer and the flexible support layer have thermochromic functions.

[0070] Example 6

[0071] The difference between this embodiment and Embodiment 1 is that the amount of catalyst added in step 2 is 0.5g.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that the furan-terminated polyurethane prepolymer is different. In this comparative example, the preparation method of the furan-terminated polyurethane prepolymer includes:

[0074] Add 5g of polyetheramine-terminated amino polyether (JEFFAMINE) ® (molecular weight 2000) and 0.15g of polyetheramine-terminated amino polyether (JEFFAMINE) ® After adding and mixing thoroughly, 1.59g of HDMI was added to the above-mentioned polyetheramine-terminated amino polyether mixture, stirred and mixed thoroughly, and placed at room temperature for 15 minutes to ensure the reaction was completed to obtain the isocyanate-terminated prepolymer; then 0.59g of furfurylamine was added to the isocyanate-terminated prepolymer, and the mixture was stirred at 2000 rpm to obtain the furan-terminated prepolymer.

[0075] The furan-terminated prepolymer prepared above was used to replace the furan prepolymer prepared in step 1 of Example 1 to prepare a smart responsive adhesive. The steps were the same as in Example 1.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that in step 1, the amount of bismaleimide crosslinking agent added is 15g, while the other steps are the same.

[0078] Comparative Example 3

[0079] The difference between this comparative example and Example 1 is that in step 1, the amount of bismaleimide crosslinking agent added is 3g, while the other steps are the same.

[0080] Comparative Example 4

[0081] The difference between this comparative example and Example 1 is that in step 1, the amount of furan-terminated polyurethane prepolymer added is 60g, while the other steps are the same.

[0082] Comparative Example 5

[0083] The difference between this comparative example and Example 1 is that in step 1, the amount of furan-terminated polyurethane prepolymer added is 30g, while the other steps are the same.

[0084] Comparative Example 6

[0085] The difference between this comparative example and Example 1 is that no catalyst is added in step 2, while all other steps are the same.

[0086] Comparative Example 7

[0087] The difference between this comparative example and Example 1 is that in step 2, the amount of catalyst added is 1g.

[0088] The heat-activated tapes prepared in the above examples and comparative examples were cut into 5cm-5cm adhesive sheets and tested. The test results are shown in Table 1.

[0089] Sample Peeling strength (N / 25mm) Static shear strength (MPa) Reversible adhesive strength ratio (cycled 5 times, %) Debonding residual rate (%) Number of repeated uses (strength retention > 80%) Example 1 12.5 3.2 92 0 8 Example 2 13.8 3.5 90 0 7 Example 3 10.2 2.8 94 0 10 Example 4 14.1 3.6 89 0 6 Example 5 12.3 3.1 91 0 8 Example 6 12.8 3.3 92 0 8 Comparative Example 1 9.5 2.4 68 15 3 Comparative Example 2 8.9 2.1 72 8 4 Comparative Example 3 11.2 2.9 75 5 5 Comparative Example 4 8.2 1.9 70 12 3 Comparative Example 5 7.8 1.7 65 18 2 Comparative Example 6 10.5 2.6 78 5 5 Comparative Example 7 12.1 3.0 85 3 6

[0090] Referring to Table 1, the performance test results of the tapes obtained in the embodiments and comparative examples of the present invention are shown. As can be seen from the results, compared with other technical solutions in the prior art, the heat-activated tape obtained by the present invention has a peel strength ≥10N / 25mm, a static shear strength ≥2.8MPa, and a reversible bonding strength ratio of ≥89% after 5 cycles, and can be reused more than 6 times (strength retention ≥80%).

[0091] In this invention, Example 3 can achieve 10 reuses (strength retention ≥80%), indicating that when the mass ratio of furan-terminated polyurethane prepolymer to bismaleimide crosslinking agent is 8:1, the side reactions in the dissociation process can be minimized by triggering the dissociation of dynamic bonds at low temperature, thereby improving the stable repeatability of the tape product.

[0092] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A smart responsive adhesive, characterized in that, It uses furan-terminated polyurethane prepolymer as diene and bismaleimide crosslinking agent as dienophile, and reacts with furan groups of furan-terminated polyurethane prepolymer through Diels-Alder reaction to form a polymer with an interpenetrating network structure containing dynamic reversible covalent bonds. The smart responsive adhesive undergoes a reversible "adhesion-slip" conformational transition when heated to the trigger temperature.

2. The smart responsive adhesive according to claim 1, characterized in that, The smart responsive adhesive is a reaction product of furan-terminated polyurethane prepolymer and bismaleimide crosslinking agent; And / or, it consists of 40 to 60 parts of furan-terminated polyurethane prepolymer and 5 to 10 parts of bismaleimide crosslinking agent; And / or, the triggering temperature of the smart responsive adhesive is 60~70℃.

3. The smart responsive adhesive according to any one of claims 1-2, characterized in that, It also includes catalysts; The catalyst is dibutyltin dilaurate or stannous octoate, preferably dibutyltin dilaurate; The amount of catalyst added is 0.1~1.5 wt% based on furan-terminated polyurethane prepolymer.

4. A method for preparing a smart responsive adhesive as described in any one of claims 1-3, characterized in that, The specific steps include: S1. Provide furan-terminated polyurethane prepolymer Polyethylene glycol (PEG) was dehydrated at 110-120°C under a vacuum of -0.095 MPa for 2 hours. After cooling to 60°C, diisocyanate was added. Under nitrogen protection, -NCO and -OH reacted at 80-85°C for 3-4 hours to obtain an isocyanate-terminated polyurethane prepolymer. After cooling to 40-50°C, furfuryl alcohol was added. The furfuryl alcohol continued to react with the remaining -NCO for 2-3 hours to obtain furan-terminated polyurethane prepolymer FPPU. Preferably, the number average molecular weight of polyethylene glycol (PEG) is 1000-2000; Preferably, the molar ratio of -NCO to -OH is 1.2~1.5:1; Preferably, the molar ratio of furfuryl alcohol to residual -NCO is 1.05~1.1:1; Preferably, the number average molecular weight of the furan-terminated polyurethane prepolymer is 3000-8000; S2. Add the bismaleimide crosslinking agent to the furan-terminated polyurethane prepolymer and stir for 15-30 minutes at 60-70°C and 200-500 rpm to uniformly disperse the bismaleimide crosslinking agent in the matrix and form a homogeneous mixture, which is the smart responsive adhesive.

5. A heat-activated tape, characterized in that, It has at least a multi-layer structure consisting of a flexible support layer, a smart responsive adhesive layer, and an interface functional layer, wherein the smart responsive adhesive layer is a smart responsive adhesive as described in any one of claims 1-2, and the flexible support layer is a polyurethane containing an elastic network of polyurea bonds.

6. The heat-activated tape according to claim 5, characterized in that, The flexible support layer is a reaction product of hydroxyl-terminated polybutadiene and diisocyanate; The mass ratio of hydroxyl-terminated polybutadiene to diisocyanate is 30~40:8~12.

7. The heat-activated tape according to claim 5, characterized in that, The interface functional layer is obtained by coating the surface of the flexible support layer with a low surface energy release resin.

8. The heat-activated tape according to any one of claims 5-7, characterized in that, It also includes a thermochromic indicator layer; The thermochromic indicator layer contains at least thermochromic microcapsules to achieve reversible thermochromism; And / or, the core material of the thermochromic microcapsule is a mixture of crystal violet lactone and bisphenol A.

9. The heat-activated tape according to any one of claims 5-7, characterized in that, The flexible support layer also includes thermochromic microcapsules with a core material that is a mixture of crystal violet lactone and bisphenol A.

10. The application of a heat-activated tape as described in any one of claims 5-9 in automotive interiors and electronic products.

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