A method for preparing epoxy adhesive joints modified by highly dispersible nanomaterials

Abstract

The present invention provides a method for preparing an epoxy adhesive joint modified by a highly dispersed nanomaterial, and belongs to the technical field of composite material connection. The method comprises: providing a first component, a second component and an epoxy adhesive, and the epoxy adhesive comprises a bisphenol A epoxy resin, an acid anhydride curing agent and nano-silicon dioxide; connecting the first component and the second component by the epoxy adhesive to obtain an epoxy adhesive joint to be cured; providing a packaging component, and packaging the epoxy adhesive joint to be cured according to a preset packaging method, and then placing it in a curing device with a vibration function, curing it according to a preset curing process to obtain an epoxy adhesive joint. The present invention improves the fracture toughness of the epoxy adhesive by adding nano-silicon dioxide to the epoxy adhesive, and uses a curing device with a vibration function to perform curing in the curing process, so as to solve the technical problem that the mechanical properties of joints prepared by existing adhesives are not good.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material connection, and in particular relates to a method for preparing an epoxy adhesive joint modified by a highly dispersed nano material. Background Art

[0002] As the issue of lightweighting in the field of transportation has received more and more attention, carbon fiber composites have become materials with great application potential for this goal due to their high specific strength, corrosion resistance and light weight. However, due to the impact of cost and manufacturing complexity, economical composite materials such as glass fiber and basalt fiber and traditional metal materials such as high-strength steel and aluminum alloy are still widely used. Therefore, it is necessary to carry out research on the multi-material connection performance of transportation vehicles.

[0003] Traditional connection methods such as bolt connection, pin connection, rivet connection, etc. will cause fiber tearing and stress concentration. Adhesive bonding can reduce stress concentration and improve the strength of heterogeneous joints. Epoxy resin is a widely used adhesive with strong adhesion and corrosion resistance. However, epoxy resin is a brittle adhesive with poor fracture toughness and is prone to early failure, which restricts its application. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an epoxy adhesive joint modified by a highly dispersed nano material, so as to solve the technical problem that the fracture toughness of the existing epoxy adhesive joint is poor.

[0005] To achieve the above-mentioned object, the present invention provides a method for preparing an epoxy adhesive joint modified by a highly dispersible nanomaterial, wherein the epoxy adhesive joint comprises a first component, and a second component partially overlapped at one end of the first component and bonded to the first component by an epoxy adhesive, wherein the first component and / or the second component is a composite material stacked by prepreg, and the method comprises the following steps: Step S10, providing a first component, a second component and an epoxy adhesive, wherein the epoxy adhesive is an epoxy adhesive modified by nano-silicon dioxide, and is prepared by the following method: firstly adding an anhydride curing agent and nano-silicon dioxide, and uniformly mixing the anhydride curing agent and the nano-silicon dioxide by a first ultrasonic vibration, then adding bisphenol A epoxy resin, and placing the resin in a water bath for stirring, and after uniform stirring, subjecting the resin to a second ultrasonic vibration and vacuum degassing. Processing to obtain the epoxy adhesive, wherein the weight ratio of the bisphenol A epoxy resin, the acid anhydride curing agent and the nano-silicon dioxide is: 1000:800:(4.5~18); step S20, first applying the epoxy adhesive to the overlapping area of ​​the first component, and then sticking the connecting end of the second component to the overlapping area of ​​the first component and fixing it to obtain the epoxy adhesive joint to be cured; step S30, providing a packaging component, and packaging the epoxy adhesive joint to be cured according to a preset packaging method, and then placing it in a curing device with a vibration function, curing it according to a preset curing process to obtain the epoxy adhesive joint, the packaging component includes a vacuum bag, and the curing device includes a mechanical vibration table for dispersing the nano-silicon dioxide during the curing process and a heater for heating.

[0006] In a specific embodiment, the preset curing process includes: evacuating the vacuum bag to 0.1Mpa; heating from room temperature, heating from room temperature to a first insulation temperature at a heating rate of 2°C / min in the first heating stage, and keeping at the first insulation temperature for 15 to 45 minutes, and heating from the first insulation temperature to a second insulation temperature at a heating rate of 2°C / min in the second heating stage, and keeping at the second insulation temperature for 120 minutes. After the insulation is completed, the temperature is lowered to 60°C to complete the curing.

[0007] In a specific embodiment, the first insulation temperature is 80°C-100°C, and the second insulation temperature is 130°C.

[0008] In a specific embodiment, the preset curing process also includes: in the first heating stage and the insulation time period at the first insulation temperature, the mechanical vibration table applies a vibration acceleration of 10g~20g; in the second heating stage, the insulation time period at the second insulation temperature, and the cooling time period, the mechanical vibration table is in a stationary state.

[0009] In a specific embodiment, the anhydride curing agent consists of MTHPA and DMP-30, and the weight ratio of MTHPA to DMP-30 is 200:1.

[0010] In a specific implementation, in step S10, the vibration time of the first ultrasonic vibration is 10 min to 20 min, the vibration time of the second ultrasonic vibration is 10 min to 20 min, and the vacuum degassing time is 10 min to 30 min.

[0011] In a specific embodiment, the packaging assembly also includes a tooling board, a first isolation film, a second isolation film, a breathable felt and a sealing strip, and the preset packaging method is specifically: from bottom to top, the tooling board, the first isolation film, the epoxy adhesive joint to be cured, the second isolation film and the breathable felt are laid flat in sequence, and then packaged with a vacuum bag and a sealing strip.

[0012] In a specific embodiment, the heater is a heating device that utilizes resistance wire hot air heating.

[0013] In a specific embodiment, the first component is a pretreated metal plate, and the second component is selected from one of a carbon fiber composite material, a glass fiber composite material and a basalt fiber composite material, wherein the metal plate is selected from one of a high-strength steel plate, an aluminum alloy plate, a titanium alloy plate and a magnesium alloy plate.

[0014] In a specific embodiment, the first component and the second component are both selected from one of a carbon fiber composite material, a glass fiber composite material and a basalt fiber composite material.

[0015] The beneficial effects of the present invention include at least:

[0016] 1. The method for preparing an epoxy adhesive joint modified with a highly dispersible nanomaterial provided by the present invention comprises: providing a first component, a second component and an epoxy adhesive, wherein the epoxy adhesive is an epoxy adhesive modified with nano-silicon dioxide, and is prepared by the following method: firstly adding an anhydride curing agent and nano-silicon dioxide, and using a first ultrasonic vibration to evenly mix the anhydride curing agent and the nano-silicon dioxide, and then adding a bisphenol A epoxy resin, and placing the mixture in a water bath for stirring, and after evenly stirring, subjecting the mixture to a second ultrasonic vibration and vacuum degassing treatment to obtain the epoxy adhesive, wherein the weight ratio of the bisphenol A epoxy resin, the anhydride curing agent and the nano-silicon dioxide is: 1000:800:(4.5~18); step S20, firstly applying the epoxy adhesive to the overlapping area of ​​the first component, and then pasting the connecting end of the second component to the overlapping area of ​​the first component and fix it to obtain an epoxy adhesive joint to be cured; step S30, provide a packaging component, and package the epoxy adhesive joint to be cured according to a preset packaging method, and then place it in a curing device with a vibration function, and cure it according to a preset curing process to obtain the epoxy adhesive joint, the packaging component includes a vacuum bag, and the curing device includes a mechanical vibration table for dispersing nano-silicon dioxide during the curing process and a heater for heating; in this way, the method provided by the present invention modifies the adhesive by adding nano-silicon dioxide to improve the fracture toughness of the epoxy adhesive, and uses a curing device with a vibration function to apply a vibration energy field during the curing process, so that the nano-silicon dioxide is not easy to agglomerate and remains in a dispersed state during the high-temperature curing process, so that the prepared epoxy adhesive joint has better fracture resistance, which solves the defect of poor fracture resistance of the adhesive joints in the prior art.

[0017] 2. The preset curing process provided by the present invention includes: vacuuming the vacuum bag to 0.1Mpa; starting from room temperature, heating from room temperature to the first insulation temperature at a heating rate of 2°C / min in the first heating stage, and keeping the temperature at the first insulation temperature for 15 to 45 minutes; heating from the first insulation temperature to the second insulation temperature at a heating rate of 2°C / min in the second heating stage, and keeping the temperature at the second insulation temperature for 120 minutes; cooling to 60°C after the insulation is completed to complete the curing; in the first heating stage and the insulation time period at the first insulation temperature, the vibration acceleration applied by the mechanical vibration table is 10g to 20g, and in the second heating stage, the insulation time period at the second insulation temperature, and the cooling time period, the mechanical vibration table is in a stationary state; In this way, the present invention applies a vibration energy field when the viscosity of the epoxy adhesive is low. On the one hand, it can disperse the distribution of nano-silicon dioxide in the epoxy adhesive, so that the toughening effect of the nano-silicon dioxide is better, and the fracture resistance of the epoxy adhesive joint is greatly improved; on the other hand, the vibration energy field can also increase the wettability of the epoxy adhesive to the surface of the first component / the second component, and reduce the dependence of the curing process on pressure.

[0018] 3. Based on the improved epoxy adhesive of the present invention, the curing device with vibration function and the preset curing process provided by the present invention are used for curing. Compared with the commonly used autoclave and autoclave curing process, the average failure strength of the prepared joint is greatly improved, and no pressure is required during the curing process, which can greatly reduce the equipment cost.

[0019] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of an epoxy adhesive joint is provided for one embodiment of the present invention;

[0021] Figure 2 A schematic flow chart of the steps of a method for preparing an epoxy adhesive joint modified with a highly dispersible nanomaterial provided in one embodiment of the present invention;

[0022] Figure 3 A process parameter diagram of a preset curing process corresponding to the curing device with a vibration function provided by the present invention;

[0023] Figure 4 A process parameter diagram of the autoclave process corresponding to the autoclave curing provided by the present invention;

[0024] Figure 5 It is a comparison chart of mechanical property test results of epoxy adhesive joints prepared in Example 1 and Comparative Examples 1 to 3;

[0025] Figure 6 The microscopic morphology of the bonding interface of the epoxy bonding joint prepared in Example 1 and Comparative Example 1 and the Si element analysis comparison diagram are shown in FIG. Figure 6 a in the figure is a SEM image of the bonding interface of the epoxy bonding joint prepared in Comparative Example 1. Figure 6 b is the Si element analysis diagram of the bonding interface of the epoxy bonding joint prepared in Comparative Example 1, Figure 6 c is a SEM image of the bonding interface of the epoxy bonding joint prepared in Example 1, Figure 6 d in the figure is the Si element distribution diagram of the bonding interface of the epoxy bonding joint prepared in Example 1;

[0026] Figure 7 This is a comparison chart of the mechanical properties test results of the epoxy bonded joints prepared in Example 2 and Comparative Example 4. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be defined and covered by various different implementations according to the claims.

[0028] See also Figure 1 and Figure 2 The present invention provides a method for preparing an epoxy adhesive joint modified by a highly dispersed nanomaterial, wherein the epoxy adhesive joint 100 comprises a first component 101, and a second component 102 partially overlapped at one end of the first component 101 and connected to the first component by an epoxy adhesive, wherein the first component 101 and / or the second component 102 are composite materials stacked by prepreg, and the method comprises the following steps:

[0029] Step S10, providing a first component 101, a second component 102 and an epoxy adhesive, wherein the epoxy adhesive is an epoxy adhesive modified with nano-silicon dioxide, which is prepared by the following method: firstly adding an anhydride curing agent and nano-silicon dioxide, and using a first ultrasonic vibration to evenly mix the anhydride curing agent and the nano-silicon dioxide, and then adding bisphenol A epoxy resin, and placing in a water bath for stirring, after stirring evenly, subjecting to a second ultrasonic vibration and vacuum degassing treatment, to obtain the epoxy adhesive, wherein the weight ratio of the bisphenol A epoxy resin, the anhydride curing agent and the nano-silicon dioxide is: 1000:800:(4.5~18).

[0030] Preferably, the first component and the second component have the same thickness.

[0031] Preferably, the first component is a pretreated metal plate, and the second component is selected from one of a carbon fiber composite material, a glass fiber composite material and a basalt fiber composite material, wherein the metal plate is selected from one of a high-strength steel plate, an aluminum alloy plate, a titanium alloy plate and a magnesium alloy plate.

[0032] It should be noted that the high-strength steel plate refers to the definition of steel plate in the prior art.

[0033] More preferably, the first component is a pretreated aluminum alloy plate, and the second component is a carbon fiber composite material.

[0034] More preferably, when the first component is a pretreated aluminum alloy plate, the pretreatment method of the aluminum alloy plate is: grinding the surface of the aluminum alloy plate in the transverse, longitudinal and circumferential directions respectively, and rinsing with clean water for 1 minute after grinding; then placing the aluminum alloy plate in a 30g / L NaOH solution for 2 minutes, and rinsing with clean water for 1 minute after immersion; then placing the aluminum alloy plate in a 300g / L HNO 3 The aluminum alloy plate was immersed in 150g / L HPO solution for 1 min, and then rinsed with clean water for 1 min. 3 Anodize in the solution for 20 minutes, and rinse with clean water for 1 minute after anodization is completed; and use a hair dryer to dry the aluminum alloy plate after each rinse with clean water.

[0035] Preferably, the first component and the second component are both selected from one of a carbon fiber composite material, a glass fiber composite material and a basalt fiber composite material.

[0036] More preferably, the first component is a carbon fiber composite material, and the second component is a glass fiber composite material.

[0037] More preferably, the carbon fiber composite material is formed by stacking 10 to 16 layers of unidirectional carbon fiber composite prepregs along the 0° direction, the glass fiber composite material is formed by stacking 10 to 20 layers of unidirectional glass fiber composite prepregs along the 0° direction, and the basalt fiber composite material is formed by stacking 10 to 20 layers of unidirectional basalt fiber composite prepregs along the 0° direction.

[0038] Preferably, the weight ratio of the bisphenol A epoxy resin, the acid anhydride curing agent and the nano-silicon dioxide is 1000:800:9.

[0039] Preferably, the anhydride curing agent consists of MTHPA and DMP-30, and the weight ratio of MTHPA to DMP-30 is 200:1.

[0040] Preferably, the vibration time of the first ultrasonic vibration is 10min~20min, the vibration time of the second ultrasonic vibration is 10min~20min, and the vacuum degassing time is 10min~30min. More preferably, the vibration time of the first ultrasonic vibration is 15min, the vibration time of the second ultrasonic vibration is 15min, and the vacuum degassing time is 15min.

[0041] In the present invention, after two ultrasonic vibrations, the nano silicon dioxide can be kept in a uniformly dispersed state during the preparation of the epoxy adhesive.

[0042] It should be noted that when adding bisphenol A epoxy resin, it is necessary to stir in a water bath because bisphenol A epoxy resin releases heat when curing, and stirring in a water bath helps to maintain a stable temperature.

[0043] Step S20: first apply epoxy adhesive to the overlapping area of ​​the first component 101, and then adhere the connecting end of the second component 102 to the overlapping area of ​​the first component 101 and fix it to obtain an epoxy adhesive joint to be cured.

[0044] In the present invention, the area of ​​the overlapping region and the coating thickness of the epoxy adhesive are determined based on the sizes of the first component and the second component, and can be specifically determined with reference to ISO 4587:2003 standard.

[0045] Step S30, providing a packaging component, and packaging the epoxy adhesive joint to be cured according to a preset packaging method, and then placing it in a curing device with a vibration function, and curing it according to a preset curing process to obtain the epoxy adhesive joint, the packaging component includes a vacuum bag, and the curing device includes a mechanical vibration table for dispersing nano-silicon dioxide during the curing process and a heater for heating.

[0046] In the present invention, the packaging assembly also includes a tooling board, a first isolation film, a second isolation film, a breathable felt and a sealing strip, and the preset packaging method is specifically: from bottom to top, the tooling board, the first isolation film, the epoxy adhesive joint to be cured, the second isolation film and the breathable felt are laid flat in sequence, and then packaged with a vacuum bag and sealant.

[0047] Preferably, the heater is a heating device that utilizes resistance wire hot air heating, specifically: heat is generated by the resistance wire, and convection heat exchange is achieved by the fan, thereby increasing the temperature in the heater cavity.

[0048] Preferably, the preset curing process includes: evacuating the vacuum bag to 0.1Mpa; heating from room temperature, heating from room temperature to a first insulation temperature at a heating rate of 2°C / min in the first heating stage, and keeping at the first insulation temperature for 15 to 45 minutes, heating from the first insulation temperature to a second insulation temperature at a heating rate of 2°C / min in the second heating stage, and keeping at the second insulation temperature for 120 minutes, and cooling to 60°C after the insulation to complete the curing.

[0049] More preferably, the first insulation temperature is 80°C-100°C, and the second insulation temperature is 130°C.

[0050] More preferably, the cooling rate from cooling to 60°C after the insulation is completed is less than 2°C / min.

[0051] Preferably, the preset curing process also includes: in the first heating stage and the insulation time period at the first insulation temperature, the vibration acceleration applied by the mechanical vibration table is 10g~20g; in the second heating stage, the insulation time period at the second insulation temperature, and the cooling time period, the mechanical vibration table is in a stationary state.

[0052] The invention improves the fracture toughness of epoxy adhesive by adding a proper amount of nano silicon dioxide into bisphenol A epoxy resin, and adopts a curing device with vibration function for curing in the curing process, thereby solving the technical problem that the joint mechanical properties of the existing adhesive are not good.

[0053] Example 1 and Comparative Examples 1 to 3

[0054] The epoxy bonded joint is composed of 2024-T3 aluminum alloy and carbon fiber composite material (T700 / TRE231) bonding, that is, the first component is an aluminum sheet made of 2024-T3 aluminum alloy, and the second component is a carbon fiber composite material (T700 / TRE231).

[0055] Example 1

[0056] Preparing epoxy bonded joints

[0057] Step (1), providing a first component and pre-treating the surface of the first component, the first component is an aluminum sheet (2024-T3 aluminum alloy), and its length × width × height = 100 mm × 25 mm × 1.5 mm, wherein the method for pre-treating the surface of the first component is specifically: grinding the surface of the aluminum sheet in the transverse, longitudinal and circumferential directions respectively, and rinsing it with clean water for 1 minute after grinding; then placing the aluminum sheet in a 30 g / L NaOH solution for 2 minutes, and rinsing it with clean water for 1 minute after soaking; then placing the aluminum sheet in a 300 g / L HNO 3Soak the aluminum sheet in the solution for 1 minute, then rinse with water for 1 minute; finally, place the aluminum sheet in 150g / L HPO 3 Anodize in the solution for 20 minutes, and rinse with clean water for 1 minute after anodization is completed; use a hair dryer to dry the aluminum sheet after each rinse with clean water.

[0058] Step (2): select unidirectional carbon fiber composite prepreg of 100 mm (length) × 200 mm (width) × 0.125 mm (height) and lay up 12 layers along the 0° direction to obtain a second component.

[0059] Step (3), preparation of epoxy adhesive: weigh and mix anhydride curing agent (800 parts) and nano-SiO 2 (9 parts), followed by ultrasonic vibration for 15 minutes; then bisphenol A epoxy resin (1000 parts) was added and placed in a water bath and stirred for 10 minutes; ultrasonic vibration for 15 minutes and vacuum barrel defoaming for 15 minutes were performed in sequence to obtain an epoxy adhesive, wherein the anhydride curing agent consists of MTHPA (methyltetrahydrophthalic anhydride) and DMP-30 [2 4, 6-tris(dimethylaminomethyl)phenol], and the weight ratio of MTHPA to DMP-30 is 200:1.

[0060] In this embodiment, nano-SiO 2 The particle size is 50nm, and the specific material used is nano-SiO provided by Bisley New Materials (Suzhou) Co., Ltd. 2 .

[0061] Step (4), evenly apply the epoxy adhesive to the overlapping area of ​​the pretreated aluminum sheet surface, and then adhere the connecting end of the second component to the overlapping area of ​​the aluminum sheet surface to obtain an epoxy adhesive joint to be cured, wherein the size of the overlapping area is length × width = 12.5 mm × 25 mm, and the thickness of the epoxy adhesive is 0.2 mm, which is specifically controlled by a 1.7 mm stainless steel gasket.

[0062] Step (5), providing a packaging component, and packaging the epoxy adhesive joint to be cured according to a preset packaging method, the packaging component includes a tooling plate, a first isolation film, a second isolation film, a breathable felt, a sealing strip and a vacuum bag, and the preset packaging method is specifically: from bottom to top, laying the tooling plate, the first isolation film, the epoxy adhesive joint to be cured, the second isolation film and the breathable felt in sequence, and then packaging with a vacuum bag and a sealant.

[0063] Step (6), placing the encapsulated epoxy adhesive joint to be cured in a curing device with a vibration function, and curing it according to a preset curing process to obtain the epoxy adhesive joint, the curing device includes a mechanical vibration table and a heater, the heater is a heating device that uses resistance wire hot air heating, specifically: heat is generated by the resistance wire, and convection heat exchange is achieved by the fan, thereby increasing the temperature in the heater cavity.

[0064] See also Figure 3 , wherein the preset curing process includes: vacuuming the vacuum bag to 0.1Mpa; starting from room temperature, heating from room temperature to 90°C at a heating rate of 2°C / min in the first heating stage, and keeping at 90°C for 30 minutes, heating from 90°C to 130°C at a heating rate of 2°C / min in the second heating stage, and keeping at 130°C for 120 minutes, and cooling to 60°C after the insulation to complete curing; in the first heating stage and the insulation time period at the first insulation temperature, the vibration acceleration applied by the mechanical vibration table is 15g, and in the second heating stage, the insulation time period at the second insulation temperature, and the cooling time period, the mechanical vibration table is in a stationary state.

[0065] Comparative Example 1

[0066] Please refer to Figure 4 Comparative Example 1 is the same as Example 1, the only difference between them is that the curing device and curing process used in step (6) are different. Example 1 uses a curing device with a vibration function, and the curing device cannot be pressurized. The curing device used in Comparative Example 1 is an autoclave, and the curing process corresponding to the autoclave (autoclave process) includes: vacuumizing the vacuum bag to 0.1 MPa; heating from room temperature, heating to 90°C at a heating rate of 2°C / min in the first heating stage, and keeping at 90°C for 30 minutes; heating from 90°C to 130°C at a heating rate of 2°C / min in the second heating stage, and keeping at 130°C for 120 minutes; after the insulation is completed, the temperature is lowered to 60°C to complete the curing; at the same time, the pressurization program is started at the beginning of the heating, and the pressure in the tank is maintained at 0.6 MPa.

[0067] It should be noted that in the autoclave process, the time from 0 MPa to 0.6 MPa and the time from 0.6 MPa to 0 MPa are both within 1 minute. Figure 4 The pressurization process and the pressure relief process are not reflected.

[0068] Comparative Example 2

[0069] Comparative Example 2 is the same as Example 1, with the only difference being that, in Example 1, an epoxy adhesive containing nano-silicon dioxide is used to connect the first component and the second component, while in Comparative Example 2, an unmodified epoxy adhesive is used to connect the first component and the second component. The step (3) of Comparative Example 2 for preparing the epoxy adhesive is as follows: bisphenol A epoxy resin (1000 parts) and an acid anhydride curing agent (800 parts) are mixed and stirred in a water bath for 10 minutes, followed by ultrasonic vibration for 15 minutes and vacuum degassing for 15 minutes to obtain the epoxy adhesive.

[0070] Comparative Example 3

[0071] Comparative Example 3 is the same as Example 1, except that the curing device and the epoxy adhesive for connecting the first component and the second component are different. The curing device used in Comparative Example 3 is an autoclave; and when connecting the first component and the second component, Comparative Example 3 uses an unmodified epoxy adhesive, that is, step (3) of Comparative Example 3 is to prepare the epoxy adhesive by mixing bisphenol A epoxy resin (1000 parts) and anhydride curing agent (800 parts), stirring in a water bath for 10 minutes, and then ultrasonically vibrating for 15 minutes and degassing in a vacuum barrel for 15 minutes to obtain the epoxy adhesive.

[0072] For the purpose of distinction, the epoxy adhesive joint prepared in Example 1 is named as 2 Adhesive-V, the epoxy adhesive joint prepared in Comparative Example 1 is named as SiO 2 The epoxy adhesive joint prepared in Comparative Example 2 was named Adhesive-A, the epoxy adhesive joint prepared in Comparative Example 2 was named Adhesive-V, and the epoxy adhesive joint prepared in Comparative Example 3 was named Adhesive-A.

[0073] It should be noted that A corresponds to the autoclave process, and V corresponds to the preset curing process.

[0074] Mechanical properties test

[0075] The lap joints (epoxy bonded joints) prepared in Implementations 1 to 4 were cut into 100 mm (length) × 25 mm (width), and then stretched on a stretching machine. 1.7 mm thick gaskets were placed on both sides of the single lap joint before clamping, and the stretching speed was set to 2 mm / min.

[0076] Mechanical properties test results are detailed in Figure 5 ,from Figure 5 It can be seen that the SiO content corresponding to the autoclave process 2 The average failure strength of adhesive-A is higher than that of adhesive without SiO 2 The average failure strength of adhesive-A increased by 2.77%; the preset curing process corresponds to the SiO 2 The average failure strength of adhesive-V is higher than that of adhesive without SiO 2The average failure strength of adhesive-V increased by 26.00%, which indicates that SiO 2 The addition of SiO helps to improve the adhesive's fracture resistance. 2 Adhesive-A and the preset curing process corresponding to the SiO 2 The average failure strength of adhesive-V of the preset curing process is compared, and it can be seen that the preset curing process performance is slightly weaker than the autoclave process, but no pressure is applied in the preset curing process, indicating that the applied vibration field can reduce the dependence of the curing process on pressure. After analysis, it is known that this is because the vibration field can also increase the wettability of the epoxy adhesive to the surface of the first component / the second component. 2 Adhesive-A with SiO2-containing 2 Compared with the average failure strength of adhesive-V of the preset curing process, the preset curing process performance is stronger than the autoclave process, indicating that the SiO 2 The more evenly distributed it is, the better its resistance to breakage.

[0077] To verify the SiO 2 The distribution of SiO is more uniform. 2 Adhesive-V and the SiO-containing adhesive prepared in Comparative Example 1 2 The microscopic morphology and Si element analysis of the bonding interface of adhesive-A were carried out. Figure 6 As shown. Figure 6 It can be seen that the Si element is concentrated in the two small areas below in the autoclave process, while the Si element is distributed more evenly in the preset curing process, indicating that the SiO in the adhesive 2 The curing process in the autoclave will cause aggregation, while the vibration applied in the early stage of the preset curing process can effectively disperse the SiO 2 .

[0078] Nano-SiO 2 It has the characteristics of high specific surface area and high stiffness, and is an ideal toughening material. However, it is easy to agglomerate due to factors such as inter-particle forces, electrostatic forces and van der Waals forces. In addition, in high-temperature cured epoxy adhesives, when the temperature is relatively high, the resin viscosity will decrease and the surface tension will weaken, resulting in an agglomeration phenomenon of nanomaterials. The present invention uses a curing device with a vibration function for curing, and applies vibration acceleration when the viscosity of the epoxy adhesive is low (the first heating stage and the first heat preservation stage) to effectively disperse SiO 2 , making SiO 2 The toughening performance can be reflected.

[0079] Example 2 and Comparative Example 4

[0080] The epoxy bonded joint is composed of a carbon fiber composite (T700 / TRE231) and a glass fiber composite (EW100A / TRE231) bonded together, that is, the first component is a carbon fiber composite and the second component is a glass fiber composite.

[0081] Example 2

[0082] Preparing epoxy bonded joints

[0083] Step (1), select unidirectional carbon fiber composite prepreg with a size of 100 mm (length) × 200 mm (width) × 0.125 mm (height) and lay up 12 layers along the 0° direction to obtain a first component.

[0084] Step (2): select unidirectional glass fiber composite prepreg of 100 mm (length) × 200 mm (width) × 0.100 mm (height) and lay up 15 layers along the 0° direction to obtain a second component.

[0085] Step (3), preparation of epoxy adhesive: weigh and mix anhydride curing agent (800 parts) and SiO 2 (9 parts), followed by ultrasonic vibration for 15 minutes; then adding bisphenol A epoxy resin (1000 parts) and placing it in a water bath and stirring for 10 minutes; then ultrasonic vibration for 15 minutes and vacuum barrel defoaming for 15 minutes are carried out in sequence to obtain an epoxy adhesive, wherein the anhydride curing agent consists of MTHPA and DMP-30, and the weight ratio of MTHPA to DMP-30 is 200:1.

[0086] Step (4), evenly apply the epoxy adhesive to the overlapping area of ​​the first component, and then adhere the connecting end of the second component to the overlapping area of ​​the first component to obtain an epoxy adhesive joint to be cured, wherein the size of the overlapping area is length × width = 12.5 × 25 mm, and the thickness of the epoxy adhesive is 0.2 mm, which is specifically controlled by a 1.7 mm stainless steel gasket.

[0087] Step (5), providing a packaging component, and packaging the epoxy adhesive joint to be cured according to a preset packaging method, the packaging component includes a vacuum bag, a tooling plate, a first isolation film, a second isolation film, a breathable felt and a sealing strip, and the preset packaging method is specifically: from bottom to top, laying the tooling plate, the first isolation film, the epoxy adhesive joint to be cured, the second isolation film and the breathable felt in sequence, and then packaging with a vacuum bag and a sealant.

[0088] Step (6), placing the encapsulated epoxy adhesive joint to be cured in a curing device with a vibration function, curing it according to a preset curing process to obtain the epoxy adhesive joint, the curing device includes a mechanical vibration table and a heater, the heater is a heating device that uses resistance wire hot air heating, specifically: heat is generated by the resistance wire, and convection heat exchange is achieved by the fan, thereby increasing the temperature in the heater cavity, wherein the preset curing process is specifically:

[0089] Please refer to Figure 3 The preset curing process includes: vacuuming the vacuum bag to 0.1Mpa; starting from room temperature, heating from room temperature to 90°C at a heating rate of 2°C / min in the first heating stage, and keeping at 90°C for 30 minutes, heating from 90°C to 130°C at a heating rate of 2°C / min in the second heating stage, and keeping at 130°C for 120 minutes, and cooling to 60°C after the insulation to complete curing; in the first heating stage and the insulation time period at the first insulation temperature, the vibration acceleration applied by the mechanical vibration table is 15g, and in the second heating stage, the insulation time period at the second insulation temperature, and the cooling time period, the mechanical vibration table is not started.

[0090] Comparative Example 4

[0091] Please refer to Figure 4 Comparative Example 4 is the same as Example 2, the only difference being that the curing device and curing process used in step (6) are different. Example 2 uses a curing device with a vibration function, and the curing device cannot be pressurized. The curing device used in Comparative Example 4 is an autoclave, and the curing process corresponding to the autoclave (autoclave process) includes: vacuumizing the vacuum bag to 0.1 MPa; heating from room temperature, heating to 90°C at a heating rate of 2°C / min in the first heating stage, and keeping the temperature at 90°C for 30 minutes; heating from 90°C to 130°C at a heating rate of 2°C / min in the second heating stage, and keeping the temperature at 130°C for 120 minutes; after the insulation is completed, the temperature is lowered to 60°C to complete the curing; at the same time, the pressurization program is started at the beginning of the heating, and the pressure in the tank is maintained at 0.6 MPa.

[0092] It should be noted that in the autoclave process, the time from 0 MPa to 0.6 MPa and the time from 0.6 MPa to 0 MPa are both within 1 minute. Figure 4 The pressurization process and the pressure relief process are not reflected.

[0093] Mechanical properties test

[0094] The joints prepared in Example 2 and Comparative Example 4 were cut into 187.5 mm (length) × 25 mm (width), and then stretched on a stretching machine. 1.7 mm thick gaskets were placed on both sides of the joint before clamping, and the stretching speed was set to 2 mm / min.

[0095] Mechanical properties test results are detailed in Figure 7 ,from Figure 7 It can be seen that the mechanical properties of the joint manufactured under the preset curing process are 7.39% higher than those of the autoclave process, indicating that the epoxy adhesive joint prepared by the method provided by the present invention has better mechanical properties.

[0096] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing an epoxy adhesive joint modified by a highly dispersible nanomaterial, the epoxy adhesive joint comprising a first component, and a second component partially overlapped at one end of the first component and bonded to the first component by an epoxy adhesive, the first component and / or the second component being a composite material stacked by prepreg, characterized in that: The method comprises the following steps: Step S10, providing a first component, a second component and an epoxy adhesive, wherein the epoxy adhesive is an epoxy adhesive modified with nano-silicon dioxide, which is prepared by the following method: firstly adding an anhydride curing agent and nano-silicon dioxide, and using a first ultrasonic vibration to evenly mix the anhydride curing agent and the nano-silicon dioxide, and then adding bisphenol A epoxy resin, placing in a water bath for stirring, stirring evenly, and then subjecting to a second ultrasonic vibration and vacuum degassing treatment to obtain the epoxy adhesive, wherein the weight ratio of the bisphenol A epoxy resin, the anhydride curing agent and the nano-silicon dioxide is: 1000:800:(4.5~18); Step S20, firstly apply the epoxy adhesive to the overlapping area of ​​the first component, and then adhere the connecting end of the second component to the overlapping area of ​​the first component and fix it to obtain an epoxy adhesive joint to be cured; Step S30, providing a packaging component, and packaging the epoxy adhesive joint to be cured according to a preset packaging method, and then placing it in a curing device with a vibration function, curing it according to a preset curing process to obtain the epoxy adhesive joint, the packaging component includes a vacuum bag, the curing device includes a mechanical vibration table for dispersing nano-silicon dioxide during the curing process and a heater for heating, wherein the preset curing process includes: evacuating the vacuum bag to 0.1MPa; heating from room temperature, heating from room temperature to the first temperature at a heating rate of 2°C / min in the first heating stage; The first temperature rising stage is a temperature of 80°C to 100°C, and the first temperature is kept warm for 15 to 45 minutes. In the second temperature rising stage, the temperature is raised from the first temperature to the second temperature of 130°C at a heating rate of 2°C / min, and the temperature is kept warm for 120 minutes at the second temperature. After the temperature is kept warm, the temperature is lowered to 60°C to complete the curing. In the first temperature rising stage and the temperature keeping period at the first temperature keeping temperature, the vibration acceleration applied by the mechanical vibration table is 10g to 20g. In the second temperature rising stage, the temperature keeping period at the second temperature keeping temperature, and the temperature dropping period, the mechanical vibration table is in a stationary state.

2. The method for preparing an epoxy adhesive joint modified with a highly dispersible nanomaterial according to claim 1, characterized in that: The anhydride curing agent consists of MTHPA and DMP-30, and the weight ratio of MTHPA to DMP-30 is 200:

1.

3. The method for preparing an epoxy adhesive joint modified with a highly dispersible nanomaterial according to claim 1, characterized in that: In step S10, the vibration time of the first ultrasonic vibration is 10 min to 20 min, the vibration time of the second ultrasonic vibration is 10 min to 20 min, and the vacuum degassing time is 10 min to 30 min.

4. The method for preparing an epoxy adhesive joint modified with a highly dispersible nanomaterial according to claim 1, characterized in that: The packaging assembly also includes a tooling plate, a first isolation film, a second isolation film, a breathable felt and a sealing strip. The preset packaging method is specifically: from bottom to top, the tooling plate, the first isolation film, the epoxy adhesive joint to be cured, the second isolation film and the breathable felt are laid flat in sequence, and then packaged with a vacuum bag and a sealing strip.

5. The method for preparing an epoxy adhesive joint modified with a highly dispersible nanomaterial according to claim 1, characterized in that: The heater is a heating device that utilizes resistance wire hot air for heating.

6. The method for preparing an epoxy adhesive joint modified with a highly dispersible nanomaterial according to claim 1, characterized in that: The first component is a pretreated metal plate, the second component is selected from one of a carbon fiber composite material, a glass fiber composite material and a basalt fiber composite material, wherein the metal plate is selected from one of a high-strength steel plate, an aluminum alloy plate, a titanium alloy plate and a magnesium alloy plate.

7. The method for preparing an epoxy adhesive joint modified with a highly dispersible nanomaterial according to claim 1, characterized in that: The first component and the second component are both selected from one of a carbon fiber composite material, a glass fiber composite material and a basalt fiber composite material.

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