Anti-fatigue pressure-sensitive adhesive and preparation method thereof

Abstract

The application belongs to the field of pressure-sensitive adhesive bonding materials, and discloses an anti-fatigue pressure-sensitive adhesive, which comprises a first adhesive layer, a structural layer and a second adhesive layer in sequence, and the structural layer comprises a plurality of structural units arranged at intervals. Through the above structural design, the anti-fatigue pressure-sensitive adhesive provided by the application can form a bridging energy dissipation zone under the action of cyclic loading or static sustained loading, thereby inhibiting crack propagation and improving the interface anti-fatigue performance and service life; the structure is suitable for various pressure-sensitive adhesive tape systems and can be applied to different substrate surfaces, and has good material applicability and commercial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of pressure-sensitive adhesive materials, specifically relating to an anti-fatigue pressure-sensitive adhesive and its preparation method. Background Technology

[0002] Pressure-sensitive adhesives (PSAs) and the tapes they produce are widely used in household, industrial manufacturing, electronic packaging, building assembly, medical and health, and safety protection fields due to their advantages such as instant bonding, ease of use, and wide applicability. Compared with traditional liquid adhesives, PSAs achieve interface bonding without an additional curing process, thus offering advantages such as ease of operation, high assembly efficiency, and suitability for continuous operations. With the development of materials technology, PSAs have achieved significant improvements in interface strength, initial adhesion, and peel performance, and are gradually replacing spot welding, screws, rivets, and liquid adhesives in some scenarios.

[0003] In recent years, with the rapid development of emerging fields such as flexible electronic devices, tissue engineering materials, and soft robots, related applications have placed higher demands on the service stability of pressure-sensitive adhesives (PSAs). Especially under dynamic loads, cyclic bending, vibration shocks, and prolonged repeated stress conditions, PSAs not only need to possess good initial adhesion but also need to maintain interface integrity and connection reliability during long-term cyclic loading. For example, in flexible electronic devices, the bonding interface needs to remain stable under repeated bending or stretching conditions; in soft robots, the bonding structure needs to withstand continuous inflation and deflation deformation or cyclic mechanical actuation; and in biomedical applications, the bonding interface may be subjected to complex and high-frequency cyclic loading environments for extended periods. Therefore, the fatigue resistance of PSAs has become a crucial indicator affecting their long-term service performance.

[0004] However, while existing pressure-sensitive adhesive products typically exhibit high adhesive strength or interfacial toughness under single-load conditions, they are prone to crack initiation, propagation, and interfacial failure under cyclic loading. Their fatigue thresholds are relatively low, making it difficult to meet the requirements of high-durability bonding applications. In other words, current technologies focus more on improving the adhesion performance of pressure-sensitive adhesives under static or rapid peeling conditions, while neglecting to improve their fatigue resistance under long-term repeated stress. Although some high-adhesion tapes possess high interfacial adhesion capabilities, their fatigue thresholds remain significantly low, leading to problems such as adhesive degradation, accelerated crack propagation, and even overall debonding failure during long-term cyclic service.

[0005] Furthermore, from a structural perspective, existing pressure-sensitive adhesives typically employ a continuous, uniform adhesive layer structure. In such structures, stress often concentrates in localized areas after the interface is loaded. Especially after crack initiation, it is difficult to form an effective energy dissipation zone near the crack tip, resulting in a rapid crack propagation rate and limited interfacial fatigue life. Therefore, how to improve the crack propagation resistance under cyclic loading, increase the interfacial fatigue threshold, and enhance long-term service stability of pressure-sensitive adhesives through reasonable structural design while maintaining their original convenient bonding characteristics has become a pressing technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a fatigue-resistant pressure-sensitive adhesive that, by arranging a structural layer comprising several spaced structural units, improves the interface fatigue resistance and service life while maintaining the rapid bonding characteristics of the pressure-sensitive adhesive.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: An anti-fatigue pressure-sensitive adhesive, comprising a first adhesive layer, a structural layer, and a second adhesive layer, wherein the structural layer comprises a plurality of spaced structural units.

[0008] In the pressure-sensitive adhesive provided by this invention, both the first adhesive layer and the second adhesive layer are composed of complete pressure-sensitive adhesive layers without patterning. The first and second adhesive layers are located on opposite sides of the structural layer, primarily providing interfacial adhesion performance while also ensuring surface sealing and protective properties. The structural layer is disposed between the first and second adhesive layers and is formed from the pressure-sensitive adhesive material through patterning. The structural layer includes several spaced structural units. Through this layered structure design, a bridging energy-dissipating zone can be formed under cyclic loading or static continuous loading, thereby improving the interfacial adhesion stability and fatigue resistance of the pressure-sensitive adhesive.

[0009] The structural unit has a discontinuous periodic structure. The structural unit is a periodically arranged columnar strip with a regular cross-sectional shape, including but not limited to rectangles, circles, and hexagons. This structural design effectively improves stress distribution and inhibits crack propagation. Preferably, the structural unit is square.

[0010] The gap area between adjacent structural units accounts for no more than 10% of the total projected area of ​​the structural layer plane.

[0011] The thickness of the structural layer is greater than the thickness of the first adhesive layer and the second adhesive layer.

[0012] Preferably, the thickness of the first adhesive layer and the second adhesive layer accounts for 10-40% of the total thickness, and the thickness of the structural layer accounts for 60-90% of the total thickness.

[0013] An interlayer reinforcement layer is provided between the first adhesive layer and the structural layer and / or between the second adhesive layer and the structural layer. The interlayer reinforcement layer may be a primer, an interface promoter, or other treatment layer capable of enhancing interlayer adhesion. Preferably, the primer is Primer 94.

[0014] During storage and transportation, a release film may also be applied to the outside of the second adhesive layer. The release film is a protective component, which is removed during use and is not an essential load-bearing layer for the fatigue-resistant structure under working conditions.

[0015] To address the problem of crack initiation and propagation, leading to interface failure, in existing pressure-sensitive adhesives under dynamic cyclic loading and long-term continuous loading, this invention provides a fatigue-resistant pressure-sensitive adhesive. The solution does not improve performance by altering the chemical composition of the pressure-sensitive adhesive material. Instead, it builds a patterned structural layer based on existing pressure-sensitive adhesive materials and stacks it with an unpatterned, complete adhesive layer. This maintains the rapid bonding characteristics of the pressure-sensitive adhesive while creating a structure that facilitates energy dissipation and inhibits crack propagation. This improves the reliability and applicability of the pressure-sensitive adhesive under dynamic loading, static continuous loading, or cyclic deformation conditions, and enhances its interface fatigue resistance and service life.

[0016] The present invention also provides a method for preparing the above-mentioned anti-fatigue pressure-sensitive adhesive, comprising: Unprocessed first pressure-sensitive adhesive material and third pressure-sensitive adhesive material serve as the first adhesive layer and the second adhesive layer, respectively; The second pressure-sensitive adhesive material is processed into the structural unit and then used as a structural layer; A structural layer is placed between the first pressure-sensitive adhesive material and the third pressure-sensitive adhesive material and then bonded and assembled to form a laminated structure, thereby obtaining an anti-fatigue pressure-sensitive adhesive.

[0017] The second pressure-sensitive adhesive material is processed into the structural unit by methods including but not limited to laser cutting and mold forming, and then used as the structural layer.

[0018] The pressure-sensitive adhesive material includes, but is not limited to, polyacrylate, rubber, polyurethane, polyolefin, polyester, etc.

[0019] Preferably, the preparation method of the anti-fatigue pressure-sensitive adhesive includes the following steps: S1. Patterning process to form structural layers The pressure-sensitive adhesive material is patterned to form a structural layer. The patterning process forms multiple spaced structural units along the thickness direction of the pressure-sensitive adhesive material, and gap regions are formed between adjacent structural units.

[0020] In some embodiments, the patterning process can be achieved using laser processing, mold forming, mechanical cutting, etc.; laser processing is preferred, and CO2 laser processing is even more preferred. The processing parameters can be adjusted according to the thickness of the pressure-sensitive adhesive material and the target structural dimensions; in a preferred embodiment, the laser processing frequency is 7 Hz to 25 Hz, the thickness of the structural unit is 0.5 mm to 2 mm, the grid size of the structural unit is 0.1 cm to 1 cm, and the gap length between adjacent structural units is 0.1 mm, so as to achieve a small proportion (< 10%) of the gap area between adjacent structural units to the planar projected area of ​​the structural layer. During processing, protective paper or release paper can be placed on non-processed surfaces to reduce the risk of surface damage.

[0021] S2, Interlayer reinforcement treatment After the structural layer is formed, an interlayer reinforcement layer can be set on the bonding interface between the structural layer and the second adhesive layer; when it is necessary to further enhance the interlayer bonding, an interlayer reinforcement layer can also be set on the corresponding interface between the structural layer and the first adhesive layer.

[0022] In some embodiments, the interlayer reinforcement layer is a primer, preferably applied by spraying, brushing, or rolling; in a preferred embodiment, the primer is Primer 94. After the primer is applied, it can be left at room temperature for a predetermined time before subsequent bonding and assembly, with a coating amount of 10 μL / cm. 2 Up to 20 μL / cm 2 After the primer is applied, allow it to stand at room temperature for 5 minutes to complete the initial curing.

[0023] S3, Layered Structure Assembly The resulting structural layer is placed between the first and second adhesive layers and then bonded together to form a laminated structure. After assembly, pressure is applied to ensure tight bonding between the layers, and the layers are left to stand at room temperature for a predetermined time to complete the bonding process.

[0024] In some embodiments, an external load may be applied during pressing; preferably, constant pressure is used for pressing. The thickness of the first adhesive layer and the second adhesive layer is 0.5 mm to 2 mm, accounting for 5-20% of the total thickness. If the product is intended for storage or transportation, a release film may be attached to the outer surface of the second adhesive layer, which is removed before actual use.

[0025] S4. Finished Product Processing Depending on the application requirements, the resulting laminated structure can be further cut, rolled, sheeted, or modularized to obtain fatigue-resistant pressure-sensitive adhesive products suitable for storage, transportation, or use.

[0026] The preparation method described in this invention can be implemented using either single-sheet processing or continuous roll processing, making it suitable for both laboratory sample preparation and industrial mass production. The patterning process can be achieved through laser processing, mold forming, mechanical cutting, etc.; the lamination assembly can be performed using roll forming, flatbed pressing, or continuous lamination. Therefore, the preparation method has good process compatibility and can be implemented in conjunction with existing pressure-sensitive adhesive tape processing, lamination, and cutting equipment, showing promising prospects for industrial application.

[0027] This invention provides an anti-fatigue pressure-sensitive adhesive and its preparation method by patterning existing pressure-sensitive adhesive materials. It is suitable for application scenarios that require maintaining interfacial bonding stability under dynamic load, static continuous load or cyclic deformation conditions, and can be applied to the bonding needs of various pressure-sensitive adhesive material systems and different substrate interfaces.

[0028] Compared with the prior art, the present invention has the following beneficial effects: 1. It has excellent fatigue resistance. This invention constructs a structural layer within a pressure-sensitive adhesive material, forming a laminated structure with the complete adhesive layer. Under cyclic loading or static continuous loading, this creates a bridging energy-dissipating zone, effectively suppressing crack initiation and propagation, and improving interfacial crack propagation resistance and fatigue threshold. Example results show that the interfacial fatigue threshold of the fatigue-resistant pressure-sensitive adhesive obtained by this invention is significantly higher than that of the unpatterned pressure-sensitive adhesive, exhibiting excellent interfacial bonding stability and fatigue resistance.

[0029] 2. The structure is clear, facilitating design and implementation. The anti-fatigue pressure-sensitive adhesive of this invention consists of a first adhesive layer, a structural layer, and a second adhesive layer. The structural layer is located between the two intact adhesive layers, and each layer has a clearly defined function. The intact adhesive layers primarily provide interfacial adhesion, surface sealing, and protective properties, while the patterned structural layer mainly improves stress distribution and forms bridging energy-dissipating areas. This structure is clearly defined, has a clear design concept, and is easy to process, manufacture, and engineer.

[0030] 3. The process route is simple and compatible with existing processing systems. This invention is based on existing pressure-sensitive adhesive materials. Fatigue resistance can be improved through patterning, interlayer reinforcement, and lamination assembly without requiring complex modifications to the chemical composition of the pressure-sensitive adhesive. The patterning process can be achieved using laser processing, die-cutting, mechanical cutting, or punching. Lamination assembly can be performed using methods such as roll forming, flatbed lamination, or continuous bonding. Therefore, it has good process compatibility and promising prospects for industrial application.

[0031] 4. It has a wide range of applications and good universality. The structural design described in this invention is not only applicable to VHB 4910, but also to VHB 5952, CIP66 PE foam tape, 9448A tissue tape, and other pressure-sensitive adhesive tape systems; simultaneously, it is applicable to substrates with various surface properties such as PMMA, glass, stainless steel, aluminum, and PTFE. The results of the embodiments show that the solution of this invention can improve interfacial toughness and / or interfacial fatigue performance under different pressure-sensitive adhesive materials and different substrate conditions, demonstrating good material and substrate applicability. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the anti-fatigue pressure-sensitive adhesive of the present invention, which includes a first adhesive layer, a structural layer and a second adhesive layer; Figure 2 This is a schematic diagram of the fatigue test of the anti-fatigue pressure-sensitive adhesive of the present invention; Figure 3 This diagram illustrates the 90-degree cyclic peeling test and the interface dynamic fatigue threshold test of the anti-fatigue pressure-sensitive adhesive of the present invention. Figure 4 The figure shows the experimental results of crack propagation rate and interface dynamic fatigue threshold of unpatterned and unpatterned samples in Example 1 of the present invention. Figures 5 to 7 The figure shows the experimental results of crack propagation length variation and interface dynamic fatigue threshold of samples with different structural layer thicknesses and different mesh sizes under different energy release rates in Example 2 of the present invention. Figure 8 The figures show the results of the 90-degree peel test on different substrates for the samples in Example 3 of this invention. Figure 9 The figure shows the experimental results of interface toughness and interface dynamic fatigue threshold of the sample on different substrates in Example 3 of the present invention; Figure 10 This is a graph showing the experimental results of interfacial toughness and interfacial dynamic fatigue threshold of different material samples on an acrylic substrate in Example 4 of the present invention; Figure 11 This is a schematic diagram of the static fatigue test of the sample on the acrylic substrate in Example 5 of the present invention; Figure 12 This is a diagram showing the results of the static fatigue threshold test of the interface on an acrylic substrate with and without patterned samples in Example 5 of the present invention. Detailed Implementation

[0033] To make the technical solution of the present invention clearer, the material preparation, process preparation and performance testing are described below with reference to specific embodiments.

[0034] The specific testing method involves bonding the fatigue-resistant pressure-sensitive adhesive sample to a backing layer during mechanical testing to facilitate load application and maintain structural stability during the test. The backing layer is used only as a testing aid and is not a necessary component of the fatigue-resistant pressure-sensitive adhesive product structure. In some embodiments, an adhesive can be applied to the surface of the backing layer, and a first adhesive layer can be bonded to the surface of the backing layer to form the test sample. The adhesive can be a fast-curing adhesive, preferably LOCTITE 401. To improve the bonding strength between the backing layer and the sample, the surface of the backing layer can be cleaned before bonding; in a preferred embodiment, cleaning is performed sequentially using water, ethanol, and acetone. After the prepared test sample is bonded to the surface of the target substrate, static load testing and / or cyclic load testing can be performed. Mechanical testing is performed after a bonding time of at least 24 hours. The target substrate can be metal, glass, acrylic, stainless steel, aluminum, polytetrafluoroethylene, or other substrates to be bonded. Test methods may include peel tests, cyclic peel tests, static peel tests, crack propagation observation, and interface fatigue threshold determination to quantitatively describe the interfacial bonding stability and fatigue resistance of anti-fatigue pressure-sensitive adhesives.

[0035] Example 1: Preparation and Dynamic Fatigue Performance Verification of VHB 4910 Anti-Fatigue Pressure-Sensitive Adhesive 1. Material preparation: 3M VHB 4910 was selected as the pressure-sensitive adhesive material. The thickness of the VHB pressure-sensitive adhesive material used to form the structural layer was selected to be 2 mm, and the thickness of the complete VHB pressure-sensitive adhesive layer used to form the first adhesive layer and the second adhesive layer was 0.5 mm. The test auxiliary backing layer was made of acrylic with a thickness of 0.1 mm. The interlayer reinforcement material was Primer 94. The adhesive between the backing layer and the first adhesive layer was LOCTITE 401.

[0036] 2. Process Preparation: First, the 0.1 mm thick acrylic backing layer was cleaned sequentially with water, ethanol, and acetone. Then, LOCTITE 401 was coated onto the backing layer surface, and a 0.5 mm thick first VHB adhesive layer was attached to the backing layer surface to form an intermediate sample for processing. Next, Primer 94 was uniformly coated onto the first VHB adhesive layer surface at a coating amount of 10 μL / cm². 2 The mixture was allowed to stand at room temperature for 5 minutes. A 2 mm thick VHB pressure-sensitive adhesive material was then pressed onto the surface of the first VHB adhesive layer, with the exposed side of the adhesive material facing upwards. A CO2 laser was used to perform a through-cutting patterning process according to a 1 mm × 1 mm grid at a laser processing frequency of 25 Hz to form a structural layer. Next, Primer 94 was applied again at a rate of 10 μL / cm² to the interface between the 0.5 mm thick second VHB adhesive layer and the structural layer. 2After being left at room temperature for 5 minutes, the layers were stacked and assembled, with the structural layer positioned between the first and second VHB adhesive layers. After assembly, the layers were pressed under a 1 kg load and allowed to stand at room temperature for 24 h to obtain a fatigue-resistant VHB pressure-sensitive adhesive sample. As a control sample, an unpatterned continuous VHB 4910 pressure-sensitive adhesive layer of the same thickness was assembled, with all other conditions kept consistent.

[0037] 3. Performance Testing and Result Analysis: A 90° peel test with cyclic loading was used to measure the dynamic fatigue threshold between patterned and unpatterned pressure-sensitive adhesive and acrylic substrate. The maximum applied force in each cycle corresponds to the maximum applied energy release rate. Crack propagation was recorded cycle by cycle. The relationship between crack propagation and the number of cycles was recorded and linearly fitted to obtain the crack propagation rate d per unit cycle. Δ / d N According to d Δ / d N With energy release rate G extrapolating its relationship curve with G The intersection of the axes is defined as the interface dynamic fatigue threshold. G The positive intercept on the axis indicates the existence of an interfacial fatigue threshold; when the energy release rate is lower than the interfacial dynamic fatigue threshold, the crack propagation rate is almost zero, and the number of cycles required for the sample to fracture increases significantly. (Combined with...) Figure 4 It is evident that the unpatterned VHB pressure-sensitive adhesive sample exhibits significant crack propagation even at a relatively low energy release rate, with an interfacial fatigue threshold of approximately 30 J / m. 2 The patterned anti-fatigue pressure-sensitive adhesive sample prepared in this embodiment can improve its interface fatigue threshold by an order of magnitude to approximately 403 J / m. 2 Furthermore, it can withstand substantial cyclic loading without significant crack propagation even under high energy release rates. These results demonstrate that the layered patterned structure described in this invention can significantly improve the dynamic fatigue resistance and interfacial bonding stability of pressure-sensitive adhesives.

[0038] Example 2: The Influence of Structural Layer Thickness and Mesh Size on Fatigue Resistance This embodiment is used to examine the effects of changes in structural layer thickness and structural unit mesh size on fatigue resistance, thereby providing a basis for determining the range of structural parameters of the present invention.

[0039] 1. Material Preparation: 3M VHB 4910 was selected as the pressure-sensitive adhesive material. The thicknesses of the pressure-sensitive adhesive material used to form the structural layers were selected as 0.5 mm, 1 mm, and 2 mm, respectively; the thickness of the complete pressure-sensitive adhesive layers used to form the first and second adhesive layers was 0.5 mm. All other auxiliary materials were the same as in Example 1.

[0040] 2. Sample Preparation: Anti-fatigue pressure-sensitive adhesive samples were prepared according to the method in Example 1. The difference was that different patterning parameters were used to process the structural layer, and the grid sizes of the structural units were set to 1 mm, 2 mm, 2.5 mm and 3.3 mm, respectively. These were combined with structural layers of different thicknesses to prepare multiple sets of parameter samples, while the other preparation conditions remained the same.

[0041] 3. Performance Testing and Result Analysis: Using the same 90° cyclic peel fatigue test method as in Example 1, the crack propagation rate and interfacial dynamic fatigue threshold of the samples under different parameter conditions were determined. Combined with... Figure 5 , Figure 6 and Figure 7 It is evident that as the structural unit size decreases and the structural layer thickness increases, the interface crack propagation rate generally decreases, while the interface fatigue threshold generally increases. Specifically, when the structural layer thickness is 2 mm and the structural unit mesh size is 1 mm, the sample exhibits superior overall fatigue resistance, demonstrating significantly better interface fatigue performance than the unpatterned sample (403 J / m²). 2 The above results demonstrate that the structural design described in this invention can improve interface fatigue performance under different parameter conditions, and exhibits superior crack propagation resistance and a higher fatigue threshold within a certain parameter range, thus providing experimental basis for the selection of structural parameters.

[0042] Example 3: Interfacial toughness and fatigue performance testing on different substrates This embodiment is used to verify the adhesion applicability of the anti-fatigue pressure-sensitive adhesive of the present invention on different substrate surfaces and its effect on improving fatigue performance.

[0043] 1. Material Preparation: The fatigue-resistant VHB pressure-sensitive adhesive sample prepared in Example 1 was used. The selected target substrates were acrylic, borosilicate glass, stainless steel, aluminum, and polytetrafluoroethylene.

[0044] 2. Sample Preparation: After preparing the anti-fatigue pressure-sensitive adhesive samples according to the method in Example 1, the obtained samples were respectively attached to the surfaces of the different substrates mentioned above. Before bonding, the surfaces of each substrate were cleaned sequentially with water, ethanol, and acetone to remove oil and surface impurities, and then pressed under a 1 kg load and allowed to stand at room temperature for 24 h.

[0045] 3. Performance Testing and Result Analysis: The interfacial toughness on different substrates was tested using a 90° peel test, and the interfacial fatigue performance on different substrates was evaluated using a cyclic peel test. An unpatterned VHB pressure-sensitive adhesive sample was used as a control group to compare and analyze the adhesive performance of the samples of this invention under different substrate conditions. Combined with... Figure 8 and Figure 9As can be seen, the anti-fatigue pressure-sensitive adhesive described in this invention exhibits good interfacial adhesion on various substrates, including acrylic, borosilicate glass, stainless steel, aluminum, and polytetrafluoroethylene. Furthermore, compared to the unpatterned control sample, its interfacial toughness and fatigue threshold are improved on multiple substrates. These results demonstrate that the structural design described in this invention is suitable not only for high surface energy substrates but also for low surface energy substrates, exhibiting good substrate applicability and interfacial stability.

[0046] Example 4: Applicability verification of the structural design of the present invention in different pressure-sensitive adhesive materials This embodiment is used to verify the applicability of the structural design described in this invention to different pressure-sensitive adhesive materials, so as to illustrate that this invention is not limited to a single material system.

[0047] 1. Material Preparation: In addition to 3M VHB 4910, VHB 5952, CIP66 PE foam tape, and 9448A tissue tape were further selected as pressure-sensitive adhesive materials to form the structural layer and the complete adhesive layer. Other auxiliary materials and processing conditions are the same as in Example 1.

[0048] 2. Sample Preparation: Following the method in Example 1, the different pressure-sensitive adhesive materials described above were subjected to patterning, interlayer reinforcement, and lamination assembly to prepare corresponding anti-fatigue pressure-sensitive adhesive samples. The patterning structural parameters of different samples can be appropriately adjusted according to the material thickness and performance characteristics, while the remaining processing steps remain consistent.

[0049] 3. Performance Testing and Result Analysis: The fatigue performance testing method, the same as or equivalent to that in Example 1, was used to evaluate the performance of samples prepared from different pressure-sensitive adhesive materials, with the corresponding unpatterned samples serving as a control group. Combined with... Figure 10 It is evident that the structural design described in this invention is applicable not only to VHB 4910, but also to different pressure-sensitive adhesive material systems such as VHB 5952, CIP66 PE foam tape, and 9448A tissue tape. After processing with the structural design of this invention, the interfacial toughness and interfacial fatigue threshold of various material samples were improved to varying degrees. These results demonstrate that this invention has good material versatility and application value.

[0050] Example 5: Fatigue performance test under static sustained load conditions This embodiment is used to verify the interface stability and crack propagation resistance of the anti-fatigue pressure-sensitive adhesive described in this invention under static continuous load conditions.

[0051] 1. Material Preparation: The patterned anti-fatigue pressure-sensitive adhesive sample prepared in Example 1 was used, and the unpatterned pressure-sensitive adhesive sample was used as a control group. Acrylic substrate was selected as the target substrate.

[0052] 2. Sample Preparation: Patterned anti-fatigue pressure-sensitive adhesive samples and unpatterned control samples were prepared according to the method in Example 1, and then attached to the surface of acrylic substrates. The surfaces of each substrate were cleaned sequentially with water, ethanol, and acetone to remove oil and surface impurities, and then pressed under a 1 kg load and allowed to stand at room temperature for 24 h.

[0053] 3. Performance Testing and Result Analysis: A 90° peel test under static load conditions was used to determine the interfacial static fatigue performance of patterned and unpatterned pressure-sensitive adhesives on acrylic substrates. Under constant load, the crack propagation rate over time was continuously recorded and linearly fitted to obtain the crack propagation rate d per unit time. Δ / d t According to d Δ / d t With energy release rate G extrapolating its relationship curve with G The intersection of the axes is defined as the static fatigue threshold of the interface.

[0054] Combination Figure 12 It can be seen that the static fatigue threshold of the unpatterned pressure-sensitive adhesive sample is approximately 13.9 J / m. 2 The static fatigue threshold of the patterned pressure-sensitive adhesive sample of this invention can be increased to approximately 146 J / m. 2 The improvement was significant compared to the unpatterned samples. G The positive intercept on the axis indicates the existence of a static fatigue threshold at the interface; when the energy release rate is below this threshold, the crack propagation rate decreases significantly and approaches zero, and the sample can still maintain high interface stability under static continuous load. These results demonstrate that the structural design described in this invention can significantly improve the interface connection stability and crack propagation resistance under static continuous load conditions.

Claims

1. A fatigue-resistant pressure-sensitive adhesive, characterized in that, The fatigue-resistant pressure-sensitive adhesive comprises, in sequence, a first adhesive layer, a structural layer, and a second adhesive layer, wherein the structural layer comprises a plurality of spaced structural units.

2. The anti-fatigue pressure-sensitive adhesive according to claim 1, characterized in that, The structural unit has a discontinuous periodic structure.

3. The anti-fatigue pressure-sensitive adhesive according to claim 2, characterized in that, The structural unit is a periodically arranged columnar strip with a regular cross-sectional shape.

4. The anti-fatigue pressure-sensitive adhesive according to claim 3, characterized in that, The cross-sectional shape of the structural unit is circular, rectangular, or hexagonal.

5. The anti-fatigue pressure-sensitive adhesive according to claim 1, characterized in that, The gap area between adjacent structural units accounts for no more than 10% of the total projected area of ​​the structural layer plane.

6. The anti-fatigue pressure-sensitive adhesive according to claim 1, characterized in that, The thickness of the structural layer is greater than the thickness of the first adhesive layer and the second adhesive layer.

7. The anti-fatigue pressure-sensitive adhesive according to claim 6, characterized in that, The thickness of the first adhesive layer and the second adhesive layer accounts for 10-40% of the total thickness, and the thickness of the structural layer accounts for 60-90% of the total thickness.

8. The anti-fatigue pressure-sensitive adhesive according to claim 1, characterized in that, An interlayer reinforcement layer is provided between the first adhesive layer and the structural layer and / or between the second adhesive layer and the structural layer.

9. A method for preparing the anti-fatigue pressure-sensitive adhesive according to any one of claims 1-8, characterized in that, include: Unprocessed first pressure-sensitive adhesive material and third pressure-sensitive adhesive material serve as the first adhesive layer and the second adhesive layer, respectively; The second pressure-sensitive adhesive material is processed into the structural unit and then used as a structural layer; A structural layer is placed between the first pressure-sensitive adhesive material and the third pressure-sensitive adhesive material and then bonded and assembled to form a laminated structure, thereby obtaining an anti-fatigue pressure-sensitive adhesive.

10. The preparation method according to claim 9, characterized in that, The pressure-sensitive adhesive material is polyacrylate, rubber, polyurethane, polyolefin, or polyester.

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