A graphene-reinforced TPU adhesive and its preparation process

Abstract

This invention discloses a graphene-reinforced TPU adhesive and its preparation process, relating to the field of polyurethane materials technology. The invention involves mixing epoxy resin and a silane coupling agent, reacting them under the catalysis of dibutyltin dilaurate to obtain a silane epoxy resin, which is then reacted with isophorone diisocyanate and polytetrahydrofuran ether diol to obtain a polyurethane prepolymer solution. Modified graphene is then added, dispersed at high speed, and a chain extender and curing agent are added. The mixture is heated to react, and after the reaction is complete, cooled to room temperature to obtain the graphene-reinforced TPU adhesive. This invention improves the mechanical strength and thermal stability of the TPU adhesive by adding modified graphene. Surface modification of graphene is achieved by using quaternary ammonium salt didodecyl dimethyl ammonium bromide as a graphene modifier. The intercalation reaction between didodecyl dimethyl ammonium bromide and graphene oxide reduces the interfacial energy between graphene and thermoplastic polyurethane, enhancing the dispersibility and barrier properties of the TPU adhesive.

Description

Technical Field

[0001] This invention relates to the field of polyurethane materials technology, specifically a graphene-reinforced TPU adhesive and its preparation process. Background Technology

[0002] Thermoplastic polyurethane (TPU), as a high-performance elastomer, is widely used in adhesives, coatings, composite materials and other fields due to its unique linear block molecular structure and controllable polymerization process.

[0003] Pressure-sensitive adhesives for aviation are mainly used for the encapsulation of aircraft components. Aircraft encapsulation materials need to maintain stable bonding performance and sealing performance under extreme environments. Currently, TPU pressure-sensitive adhesives are widely used for aircraft encapsulation.

[0004] Traditional single-component TPU adhesives have low strength and cannot meet the requirements of aircraft encapsulation. Existing technologies use nano-inorganic fillers (e.g., glass fiber, carbon fiber, silica, titanium dioxide, etc.) added to the TPU matrix to enhance the mechanical properties of the TPU elastomer. Due to the urgent need for lightweight materials in the aerospace field, graphene, as a high-strength nanomaterial with a Young's modulus close to 1 TPa, can significantly improve the mechanical properties and gas barrier properties of the TPU matrix, achieving both weight reduction and improved mechanical performance. However, it still suffers from insufficient dispersion and agglomeration within the TPU adhesive matrix. Therefore, this invention proposes a graphene-reinforced TPU adhesive and its preparation process to solve the aforementioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a graphene-reinforced TPU adhesive and its preparation process to solve the problems raised in the prior art.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] A preparation process for a graphene-reinforced TPU adhesive, specifically as follows:

[0008] S1: Mix thermosetting epoxy resin and silane coupling agent, add dibutyltin dilaurate, purge with nitrogen gas, and react at 55~60℃ for 2~3h to obtain silane epoxy resin.

[0009] S2: Dissolve silane epoxy resin in toluene, then add isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate. Stir until homogeneous and react under nitrogen atmosphere for 3.5-4 hours to obtain polyurethane prepolymer solution.

[0010] S3: Add modified graphene to the polyurethane prepolymer solution, disperse at high speed, add chain extender and polyetheramine, stir, heat to 50~60℃, react for 4~6h, and after the reaction is completed, cool to room temperature to obtain graphene-reinforced TPU adhesive.

[0011] In the above technical solution, this invention introduces thermosetting epoxy resin to enhance the surface adhesion, thermal stability, and chemical resistance of TPU adhesive. The abundant epoxy groups and hydroxyl groups on its surface impart adhesive strength to the TPU adhesive. Pretreatment of the epoxy resin with a silane coupling agent improves the compatibility between the epoxy resin and the polyurethane matrix. Dibutyltin dilaurate acts as a catalyst, and the amino groups on the silane coupling agent undergo a ring-opening reaction with the epoxy resin to form stable CN bonds. Simultaneously, hydroxyl groups are generated on adjacent C atoms during the ring-opening reaction. The benzene ring structure in the epoxy resin provides a rigid framework, while the flexible interface layer formed by the silane coupling agent can relax stress and prevent crack propagation. A compatible interface was constructed for the subsequent introduction of modified graphene. After the epoxy resin undergoes ring-opening, the hydroxyl groups generated condense with the isocyanate groups to form urethane bonds (-NHCOO-), and copolymerization produces a cross-linked network, which significantly enhances the mechanical strength of the material. The multiphase microstructure enables the material to simultaneously possess high modulus, high elasticity, and excellent heat resistance. The introduction of modified graphene into TPU adhesive increases the thermal decomposition temperature of TPU adhesive. The silane epoxy resin and modified graphene have a synergistic effect, increasing the mechanical strength of TPU adhesive while improving its thermal stability. Chain extenders are added to adjust hardness and elasticity. Polyetheramine is used as a curing agent to accelerate the formation of the cross-linked network.

[0012] The modified graphene is prepared by the following process:

[0013] Step 1: Add graphene oxide to N,N dimethylformamide and disperse by ultrasonication to obtain a graphene oxide suspension;

[0014] Step 2: Add the graphene oxide suspension to dodecyl dimethyl ammonium bromide, stir for 10-12 hours under a nitrogen atmosphere, then add vitamin C, heat to 90-95℃, continue stirring for 4-6 hours, filter, wash, and dry to obtain modified graphene.

[0015] In the above technical solution, quaternary ammonium salts can be used as surfactants or as antistatic agents for TPU. This invention uses the quaternary ammonium salt didodecyl dimethyl ammonium bromide as a modifier for graphene. Didodecyl dimethyl ammonium bromide undergoes an intercalation reaction with graphene oxide. Utilizing the delocalized π bonds formed by the unoxidized sp2 hybrid carbon atoms on the surface of graphene oxide, and the electrostatic interaction between the carboxyl groups at the edge of graphene oxide and the didodecyl dimethyl ammonium bromide cations, didodecyl dimethyl ammonium bromide molecules are inserted into the interlayer of graphene oxide. Then, reduction is performed using vitamin C, and the quaternary ammonium salt cations interact electrostatically. The modified graphene oxide is coated with hydrophobic bonds to effectively prevent π-stacking between the sheets. The active groups (such as hydroxyl and carboxyl groups) on the structural layer of the quaternary ammonium salt graphene are reduced and cannot form aggregates along the basal plane. After drying, a loose structure is formed with a large distance between the sheets, thereby reducing their interaction forces and allowing them to be well dispersed in TPU adhesive. The aromatic conjugated structure of the modified graphene itself allows it to capture and couple free radicals generated during the high-temperature decomposition of TPU, effectively hindering the further decomposition of TPU molecular chains and improving the thermal stability of TPU adhesive.

[0016] Furthermore, the mass ratio of graphene oxide to N,N dimethylformamide is (0.2~0.5):80.

[0017] Furthermore, the dodecyl dimethyl ammonium bromide accounts for 2% to 5% of the total mass of the reaction system.

[0018] Furthermore, vitamin C accounts for 1% to 3% of the total mass of the reaction system.

[0019] Furthermore, the mass ratio of epoxy resin, silane coupling agent, and dibutyltin dilaurate is 20:(1~3):(0.1~0.2).

[0020] Furthermore, the mass ratio of silane epoxy resin, toluene, isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate is 15:(30~40):30:85:0.2.

[0021] Furthermore, the mass ratio of polyurethane prepolymer solution, modified graphene, chain extender, and polyetheramine is 100:(1~3):(5~10):(5~8).

[0022] Further, the chain extender is any one of 1,4-butanediol, 1,4-butanediamine, 1,6-hexanediamine, 1,10-decanediamine, and 1,12-dodecyldiamine.

[0023] Furthermore, the silane coupling agent is KH-550.

[0024] A graphene-reinforced TPU adhesive is prepared using the aforementioned preparation process for graphene-reinforced TPU adhesive.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. This invention enhances the surface adhesion, thermal stability, and chemical resistance of TPU adhesive by introducing thermosetting epoxy resin. The epoxy groups and hydroxyl groups abundant on its surface endow the TPU adhesive with bonding strength. Pretreatment of the epoxy resin with a silane coupling agent improves the compatibility between the epoxy resin and the polyurethane matrix. The benzene ring structure in the epoxy resin provides a rigid framework, while the flexible interface layer formed by the silane coupling agent can relax stress and prevent crack propagation, thus constructing a compatible interface for the subsequent introduction of modified graphene. After the epoxy resin undergoes ring opening, the hydroxyl groups generated condense with the isocyanate groups, copolymerizing to form a cross-linked network, which significantly enhances the mechanical strength of the material. The multiphase microstructure enables the material to simultaneously possess high modulus, high elasticity, and excellent heat resistance.

[0027] 2. This invention introduces modified graphene into TPU adhesive, which increases the thermal decomposition temperature of TPU adhesive. The silane epoxy resin and modified graphene have a synergistic effect, which increases the mechanical strength of TPU adhesive while improving its thermal stability.

[0028] 3. In this invention, the quaternary ammonium salt didodecyl dimethyl ammonium bromide is used as a modifier for graphene. Didodecyl dimethyl ammonium bromide undergoes an intercalation reaction with graphene oxide, utilizing the unoxidized SP on the surface of the graphene oxide. 2 The delocalized π bonds formed by hybrid carbon atoms and the electrostatic interaction between the carboxyl groups at the edge of graphene oxide and the didodecyl dimethylammonium bromide cations allow didodecyl dimethylammonium bromide molecules to insert into the interlayer of graphene oxide. Further reduction with vitamin C allows the quaternary ammonium salt cations to coat the reduced graphene oxide surface through electrostatic and hydrophobic interactions, effectively preventing π-stacking between layers. After reduction, the active groups (such as hydroxyl and carboxyl groups) on the graphene's structural layers are reduced and cannot form aggregates along the basal plane. After drying, a loose structure is formed with larger distances between the layers, thus reducing their interaction forces and allowing for good dispersion in the TPU adhesive. The modified graphene's own aromatic conjugated structure enables it to capture and couple free radicals generated during the high-temperature decomposition of TPU, effectively hindering further decomposition of the TPU molecular chains and improving the thermal stability of the TPU adhesive. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments.

[0030] In the following specific implementation:

[0031] Epoxy resin, model E-51, CAS: 61788-97-4;

[0032] Silane coupling agent, model KH-550;

[0033] Dibutyltin dilaurate, CAS: 77-58-7;

[0034] Isophorone diisocyanate, CAS: 4098-71-9;

[0035] Polytetrahydrofuran ether diol, with an average molecular weight of 1000, CAS: 25190-06-1;

[0036] Polyetheramine, model D-230, CAS: 9046-10-0;

[0037] Graphene oxide, monolayer, 99.9% purity, average sheet diameter 0.5μm;

[0038] NN dimethylformamide, CAS: 68-12-2;

[0039] Didodecyl dimethylammonium bromide, CAS: 3282-73-3;

[0040] Vitamin C, CAS: 50-81-7.

[0041] Example 1

[0042] A preparation process for graphene-reinforced TPU adhesive includes the following steps:

[0043] S1: Mix epoxy resin and silane coupling agent, add dibutyltin dilaurate, purge with nitrogen gas, and react at 55°C for 2 hours to obtain silane epoxy resin; the mass ratio of epoxy resin, silane coupling agent, and dibutyltin dilaurate is 20:1:0.1.

[0044] S2: Dissolve silane epoxy resin in toluene, then add isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate. Stir until homogeneous and react under a nitrogen atmosphere for 3.5 h to obtain a polyurethane prepolymer solution. The mass ratio of silane epoxy resin, toluene, isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate is 15:30:30:85:0.2.

[0045] S3: Add modified graphene to the polyurethane prepolymer solution, disperse at high speed, add 1,4-butanediol and polyetheramine, stir, heat to 50℃, react for 4 hours, and then cool to room temperature after the reaction to obtain graphene-reinforced TPU adhesive; the mass ratio of polyurethane prepolymer solution, modified graphene, 1,4-butanediol and polyetheramine is 100:1:5:5.

[0046] The modified graphene is prepared by the following process:

[0047] Step 1: Add graphene oxide to N,N dimethylformamide and disperse by ultrasonication to obtain a graphene oxide suspension; the mass ratio of graphene oxide to N,N dimethylformamide is 0.2:80.

[0048] Step 2: Add the graphene oxide suspension to dodecyl dimethyl ammonium bromide, stir for 10 hours under a nitrogen atmosphere, then add vitamin C, heat to 90°C, continue stirring for 4 hours, filter, wash, and dry to obtain modified graphene; dodecyl dimethyl ammonium bromide accounts for 2% of the total mass of the reaction system; vitamin C accounts for 1% of the total mass of the reaction system.

[0049] Example 2

[0050] A preparation process for graphene-reinforced TPU adhesive includes the following steps:

[0051] S1: Mix epoxy resin and silane coupling agent, add dibutyltin dilaurate, purge with nitrogen gas, and react at 58°C for 2.5 h to obtain silane epoxy resin; the mass ratio of epoxy resin, silane coupling agent, and dibutyltin dilaurate is 20:2:0.1.

[0052] S2: Dissolve silane epoxy resin in toluene, then add isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate. Stir until homogeneous and react under a nitrogen atmosphere for 3.5 h to obtain a polyurethane prepolymer solution. The mass ratio of silane epoxy resin, toluene, isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate is 15:35:30:85:0.2.

[0053] S3: Add modified graphene to the polyurethane prepolymer solution, disperse at high speed, add 1,4-butanediamine and polyetheramine, stir, heat to 50~60℃, react for 4~6h, and cool to room temperature after the reaction to obtain graphene-reinforced TPU adhesive; the mass ratio of polyurethane prepolymer solution, modified graphene, 1,4-butanediamine and polyetheramine is 100∶2∶8∶6.

[0054] The modified graphene is prepared by the following process:

[0055] Step 1: Add graphene oxide to N,N dimethylformamide and disperse by ultrasonication to obtain a graphene oxide suspension; the mass ratio of graphene oxide to N,N dimethylformamide is 0.3:80.

[0056] Step 2: Add the graphene oxide suspension to dodecyl dimethyl ammonium bromide, stir for 10 hours under a nitrogen atmosphere, then add vitamin C, heat to 90°C, continue stirring for 4 hours, filter, wash, and dry to obtain modified graphene; dodecyl dimethyl ammonium bromide accounts for 3% of the total mass of the reaction system; vitamin C accounts for 2% of the total mass of the reaction system.

[0057] Example 3

[0058] A preparation process for graphene-reinforced TPU adhesive includes the following steps:

[0059] S1: Mix epoxy resin and silane coupling agent, add dibutyltin dilaurate, purge with nitrogen gas, and react at 60°C for 3 hours to obtain silane epoxy resin; the mass ratio of epoxy resin, silane coupling agent, and dibutyltin dilaurate is 20:3:0.2.

[0060] S2: Dissolve silane epoxy resin in toluene, then add isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate. Stir until homogeneous and react under a nitrogen atmosphere for 4 hours to obtain a polyurethane prepolymer solution. The mass ratio of silane epoxy resin, toluene, isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate is 15:40:30:85:0.2.

[0061] S3: Modified graphene was added to the polyurethane prepolymer solution and dispersed at high speed. 1,6-hexanediamine and polyetheramine were added, stirred, heated to 60°C, and reacted for 6 hours. After the reaction was completed, the temperature was lowered to room temperature to obtain graphene-reinforced TPU adhesive. The mass ratio of polyurethane prepolymer solution, modified graphene, 1,6-hexanediamine, and polyetheramine was 100:3:10:8.

[0062] The modified graphene is prepared by the following process:

[0063] Step 1: Add graphene oxide to N,N dimethylformamide and disperse by ultrasonication to obtain a graphene oxide suspension; the mass ratio of graphene oxide to N,N dimethylformamide is 0.5:80.

[0064] Step 2: Add the graphene oxide suspension to dodecyl dimethyl ammonium bromide, stir for 12 hours under a nitrogen atmosphere, then add vitamin C, heat to 95°C, continue stirring for 6 hours, filter, wash, and dry to obtain modified graphene; dodecyl dimethyl ammonium bromide accounts for 5% of the total mass of the reaction system; vitamin C accounts for 3% of the total mass of the reaction system.

[0065] Comparative Example 1

[0066] This comparative example provides a preparation process for graphene-reinforced TPU adhesive, including the following processes:

[0067] S1: Mix epoxy resin and silane coupling agent, add dibutyltin dilaurate, purge with nitrogen gas, and react at 55°C for 2 hours to obtain silane epoxy resin; the mass ratio of epoxy resin, silane coupling agent, and dibutyltin dilaurate is 20:1:0.1.

[0068] S2: Dissolve silane epoxy resin in toluene, then add isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate. Stir until homogeneous and react under a nitrogen atmosphere for 3.5 h to obtain a polyurethane prepolymer solution. The mass ratio of silane epoxy resin, toluene, isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate is 15:30:30:85:0.2.

[0069] S3: Add graphene oxide to the polyurethane prepolymer solution, disperse at high speed, add 1,4-butanediol and polyetheramine, stir, heat to 50℃, react for 4 hours, and cool to room temperature after the reaction is completed to obtain graphene-reinforced TPU adhesive; the mass ratio of polyurethane prepolymer solution, graphene oxide, 1,4-butanediol and polyetheramine is 100:1:5:5.

[0070] Comparative Example 2

[0071] This comparative example provides a preparation process for graphene-reinforced TPU adhesive, including the following processes:

[0072] S1: Mix epoxy resin with acetone, then add isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate. Stir until homogeneous and react under a nitrogen atmosphere for 3.5 h to obtain a polyurethane prepolymer solution. The mass ratio of epoxy resin, toluene, isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate is 15:5:30:85:0.2.

[0073] S2: Modified graphene was added to the polyurethane prepolymer solution and dispersed at high speed. 1,4-Butanediol and polyetheramine were added, stirred, heated to 50°C, and reacted for 4 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain graphene-reinforced TPU adhesive. The mass ratio of polyurethane prepolymer solution, modified graphene, 1,4-Butanediol, and polyetheramine was 100:1:5:5. The remaining methods were the same as in Example 1.

[0074] Comparative Example 3

[0075] This comparative example provides a preparation process for graphene-reinforced TPU adhesive, including the following processes:

[0076] S1: Mix isophorone diisocyanate and polytetrahydrofuran ether diol, add dibutyltin dilaurate, stir evenly, and react under nitrogen atmosphere for 3.5 h to obtain polyurethane prepolymer solution; the mass ratio of isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate is 30:85:0.2.

[0077] S2: Modified graphene was added to the polyurethane prepolymer solution and dispersed at high speed. 1,4-Butanediol and polyetheramine were added, stirred, heated to 55°C, and reacted for 4 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain graphene-reinforced TPU adhesive. The mass ratio of polyurethane prepolymer solution, modified graphene, 1,4-Butanediol, and polyetheramine was 100:1:5:5. The remaining methods were the same as in Example 1.

[0078] Comparative Example 4

[0079] This comparative example provides a preparation process for graphene-reinforced TPU adhesive, including the following processes:

[0080] S1: Mix isophorone diisocyanate and polytetrahydrofuran ether diol, add dibutyltin dilaurate, stir evenly, and react under nitrogen atmosphere for 3.5 h to obtain polyurethane prepolymer solution; the mass ratio of isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate is 30:85:0.2.

[0081] S2: Add graphene oxide to the polyurethane prepolymer solution, disperse at high speed, add 1,4-butanediol and polyetheramine, stir, heat to 55°C, react for 4 hours, and then cool to room temperature after the reaction is complete to obtain graphene-reinforced TPU adhesive. The mass ratio of polyurethane prepolymer solution, graphene oxide, 1,4-butanediol and polyetheramine is 100:1:5:5. The remaining methods are the same as in Example 1.

[0082] experiment:

[0083] The graphene-reinforced TPU adhesives obtained in Examples 1-3 and Comparative Examples 1-4 were used to prepare samples, and their properties were tested and the test results were recorded.

[0084] Tensile strength test: Using GB / T 43128-2023 as the reference standard, the obtained graphene-reinforced TPU adhesive was poured into a mold and cured at 120℃ for 4 hours to obtain a sample; using a universal testing machine, the maximum tensile stress during the process of stretching the sample to the point of fracture was tested at a rate of 50 mm / min.

[0085] Elongation at break test: GB / T 43128-2023 is used as the reference standard. The specimen preparation is the same as that for tensile strength test. A universal testing machine is used to test the elongation at break of the specimen at a rate of 50 mm / min.

[0086] Bond strength test: Using GB / T 43128-2023 as the reference standard, the obtained graphene-reinforced TPU adhesive was coated onto a glass substrate, and then a flexible metal sheet aluminum plate was covered on top. The sample was then roll-formed. The unbonded end of the flexible metal sheet of the sample was passed between the two rollers of the clamp, and the flexible metal sheet was clamped at the jaw position of the clamp so that the raised part of the flexible metal sheet was perpendicular to the glass substrate. The two sides of the sample should not contact the clamp frame. The testing machine was turned on to perform peeling, and the peeling displacement was at least 120 mm. The bond strength of the sample was then tested. The thickness of the aluminum plate was 0.3 mm; the thickness of the TPU adhesive layer was 0.63 mm; and the thickness of the glass substrate was 9 mm.

[0087] Heat resistance test: Using GB / T 43128-2023 as the reference standard, the obtained graphene-reinforced TPU adhesive was poured into a mold and cured at 120℃ for 4 hours. Then, it was sandwiched between two pieces of glass and assembled. The upper surfaces of the glass should be parallel. Then, it was steam-pressed to obtain the sample. The sample was placed in an electric heating oven, heated to 100℃, and kept at that temperature for 2 hours. The heat resistance was visually inspected and recorded.

[0088] Performance test results

[0089]

[0090] Based on the data in the table above, the following conclusions can be clearly drawn:

[0091] The graphene-reinforced TPU adhesives obtained in Examples 1-3 were compared with those in Comparative Examples 1-4. The test results show that:

[0092] Compared with the comparative examples, the graphene-reinforced TPU adhesives obtained in Examples 1-3 have high tensile strength, high elongation at break, high bond strength, and excellent heat resistance.

[0093] Compared to Example 1, the graphene-reinforced TPU adhesive obtained in Comparative Example 1 exhibited lower tensile strength, lower elongation at break, lower bond strength, and reduced heat resistance. This indicates that directly adding graphene oxide as a reinforcing phase results in the graphene oxide failing to disperse uniformly in the thermoplastic polyurethane, easily leading to agglomeration and performance degradation.

[0094] Compared with Example 1, the graphene-reinforced TPU adhesive obtained in Comparative Example 2 has lower tensile strength, lower elongation at break, lower bond strength, and reduced heat resistance. This indicates that directly copolymerizing epoxy resin with thermoplastic polyurethane results in slightly better mechanical properties compared to other comparative examples. It shows that epoxy resin has a certain effect on enhancing the mechanical properties of TPU adhesive, but its effect is not as good as that of silane coupling agent modification when used alone.

[0095] Compared with Example 1, the graphene-reinforced TPU adhesive obtained in Comparative Example 3 has low tensile strength, low elongation at break, low bond strength, and reduced heat resistance. Since epoxy resin and thermoplastic polyurethane were not copolymerized, the mechanical properties of the TPU adhesive were significantly reduced and the heat resistance was poor, failing to achieve the technical effect desired by this application.

[0096] Compared with Example 1, the graphene-reinforced TPU adhesive obtained in Comparative Example 4 has lower tensile strength, lower elongation at break, lower bond strength, and reduced heat resistance. This indicates that the TPU adhesive obtained by directly blending graphene oxide with polyurethane prepolymer and then using a chain extender and curing cannot achieve the technical effect desired by this application.

[0097] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A preparation process for graphene-reinforced TPU adhesive, characterized in that, Specifically: S1: Mix thermosetting epoxy resin and silane coupling agent, add dibutyltin dilaurate, purge with nitrogen gas, and react at 55~60℃ for 2~3h to obtain silane epoxy resin. S2: Dissolve silane epoxy resin in toluene, then add isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate. Stir until homogeneous and react under nitrogen atmosphere for 3.5-4 hours to obtain polyurethane prepolymer solution. S3: Add modified graphene to the polyurethane prepolymer solution, disperse at high speed, add chain extender and polyetheramine, stir, heat to 50~60℃, react for 4~6h, and after the reaction is completed, cool to room temperature to obtain graphene-reinforced TPU adhesive. The modified graphene is prepared by the following process: Step 1: Add graphene oxide to N,N-dimethylformamide and disperse by ultrasonication to obtain a graphene oxide suspension; Step 2: Add the graphene oxide suspension to dodecyl dimethyl ammonium bromide, stir for 10-12 hours under a nitrogen atmosphere, then add vitamin C, heat to 90-95℃, continue stirring for 4-6 hours, filter, wash, and dry to obtain modified graphene. The mass ratio of graphene oxide to N,N-dimethylformamide is (0.2~0.5):80; The content of didodecyl dimethyl ammonium bromide in the total reaction system is 2% to 5% by mass; Vitamin C accounts for 1% to 3% of the total mass of the reaction system; The mass ratio of thermosetting epoxy resin, silane coupling agent, and dibutyltin dilaurate is 20:(1~3):(0.1~0.2). The mass ratio of silane epoxy resin, toluene, isophorone diisocyanate, polytetrahydrofuran ether diol, and dibutyltin dilaurate is 15:(30~40):30:85:0.2; The mass ratio of polyurethane prepolymer solution, modified graphene, chain extender and polyetheramine is 100: (1~3): (5~10): (5~8).

2. The preparation process of a graphene-reinforced TPU adhesive according to claim 1, characterized in that, The chain extender is any one of 1,4-butanediol, 1,4-butanediamine, 1,6-hexanediamine, 1,10-decanediamine, and 1,12-dodecyldiamine.

3. The preparation process of a graphene-reinforced TPU adhesive according to claim 1, characterized in that, The silane coupling agent is KH-550.

4. A graphene-reinforced TPU adhesive, characterized in that, The graphene-reinforced TPU adhesive is prepared using the preparation process described in any one of claims 1-3.

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