Method for removing thermal curing OCA residue

Abstract

This invention discloses a method for removing thermosetting OCA residue, belonging to the field of optical adhesive rework technology. The method includes: spraying anhydrous ethanol onto the surface of the workpiece with the thermosetting OCA residue layer, allowing it to stand for 30-120 seconds to induce initial swelling and the formation of nanoporous channels within the residue layer; spraying water onto the surface of the initially swollen residue layer, allowing it to stand for at least 10 seconds to allow the water to penetrate into the residue layer along the nanoporous channels, causing secondary swelling and overall whitening of the residue layer, and interface detachment; and then peeling the secondary swollen and detached residue layer entirely off the workpiece surface. This invention, through a three-step synergy of "anhydrous ethanol pre-swelling to create pores—water-induced secondary swelling—physical overall peeling," can achieve rapid and thorough removal of thermosetting OCA residue while effectively protecting the workpiece substrate from damage. It is simple to operate, low in cost, and particularly suitable for rework scenarios involving optical components such as touchscreens, foldable screens, and automotive display modules.

Description

Technical Field

[0001] This invention belongs to the field of optical adhesive re-disassembly technology, specifically relating to a method for removing residual thermosetting OCA adhesive. Background Technology

[0002] Thermosetting OCA (Optically Clear Adhesive) typically uses cross-linked acrylate as the main resin. It is a high-performance optical bonding material that cures upon heating to form a dense three-dimensional network, exhibiting excellent adhesive strength, temperature resistance, and weather resistance. Unlike thermoplastic OCA or UV-cured OCA, thermosetting OCA forms a permanent cross-linked network after curing. This network is not only insoluble in common organic solvents and deionized water, but also cannot be softened or melted by secondary heating, making its re-demolding process significantly more difficult.

[0003] In the manufacturing processes of touchscreens, foldable screens, and automotive display modules, thermoset OCA is widely used in the vacuum bonding process between the cover glass and the panel. When defects such as bonding misalignment, bubbles, or bright spots occur, the component must be disassembled. However, because the interfacial bonding force between thermoset OCA and the substrate is usually greater than its own cohesive force, the disassembly process can easily cause interfacial residue or cohesive breakage, resulting in a large area of ​​continuous adhesive residue on the substrate surface. Therefore, before performing secondary bonding, the residual OCA adhesive layer must be thoroughly removed.

[0004] Currently, methods for removing residual adhesive from thermosetting OCA mainly include mechanical scraping, immersion in strong corrosive solvents, and plasma dry cleaning. Although these methods can remove residual adhesive under certain conditions, each has significant drawbacks: mechanical scraping can easily cause physical damage to the substrate and is difficult to avoid the residue of tiny debris; immersion in strong corrosive solvents is corrosive to the component structure and has high environmental costs for wastewater treatment; and plasma dry cleaning is inefficient and cannot meet the process cycle requirements of large-scale, batch production lines.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for removing thermosetting OCA residue, which can quickly and thoroughly remove thermosetting OCA residue while effectively protecting the workpiece (substrate) from damage. The removal process is simple to operate and has low overall cost.

[0007] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution: a method for removing thermosetting OCA residue, used to remove thermosetting OCA residue layers from workpieces, the removal method comprising the following steps:

[0008] Anhydrous ethanol is sprayed onto the residual adhesive layer on the surface of the workpiece and left to stand for a first preset time to allow the residual adhesive layer to initially swell and form nanoporous channels inside. The first preset time is 30~120s.

[0009] Water is sprayed onto the surface of the initially swollen residual adhesive layer and left to stand for a second preset time, allowing the water to seep into the interior of the residual adhesive layer along the nanopore channels, causing the residual adhesive layer to swell a second time and turn white as a whole, so as to reduce the adhesion between the residual adhesive layer and the workpiece. The second preset time is greater than or equal to 10s.

[0010] The residual adhesive layer after secondary swelling is peeled off the entire surface of the workpiece.

[0011] In one or more embodiments of the present invention, the thermosetting OCA is an acrylate thermosetting OCA.

[0012] In one or more embodiments of the present invention, the thickness of the residual adhesive layer is 10~100μm.

[0013] In one or more embodiments of the present invention, the first preset duration is 30 to 60 seconds.

[0014] In one or more embodiments of the present invention, the second preset duration is 10 to 30 seconds.

[0015] In one or more embodiments of the present invention, the ambient temperature during which the cleaning method is performed is 20~28°C; and / or,

[0016] The temperatures of the anhydrous ethanol and the water are 20~28℃, respectively.

[0017] In one or more embodiments of the present invention, in the step of spraying anhydrous ethanol onto the residual adhesive layer on the workpiece surface, the time from the start of spraying to complete coverage of the residual adhesive is 1 to 10 seconds.

[0018] In one or more embodiments of the present invention, the anhydrous ethanol is sprayed by low-pressure atomization spraying, with a spraying pressure of 0.05~0.1MPa.

[0019] In one or more embodiments of the present invention, in the step of spraying water onto the surface of the pre-swollen residual adhesive layer, the water is deionized water.

[0020] In one or more embodiments of the present invention, the purity of the anhydrous ethanol is greater than or equal to 99.5%.

[0021] Compared with the prior art, the method for removing thermosetting OCA residue of the present invention, through a three-step synergistic mechanism of "initial swelling and pore creation with anhydrous ethanol - secondary swelling induced by water washing - physical overall peeling", can achieve rapid and thorough removal of thermosetting OCA residue without damaging the workpiece substrate.

[0022] Specifically, in this method, anhydrous ethanol first independently penetrates into the gaps of the thermosetting OCA permanent cross-linked network, causing the residual adhesive layer to undergo initial uniform swelling. Within this layer, the original gaps are expanded into nanoscale pore channels, significantly weakening its cohesive strength. Subsequently, water is sprayed onto the surface of this initially swollen residual adhesive layer. This allows water molecules, which were previously difficult to penetrate the thermosetting OCA permanent cross-linked network, to enter the aforementioned nanoscale pore channels under the combined effects of ethanol-water miscibility and capillary action. These water molecules then associate with the ethanol molecules within the channels, forming larger alcohol-water associated clusters. These alcohol-water associated clusters generate… The volume occupancy effect continuously compresses and expands the polymer chain segments of the cross-linked network, promoting pore expansion, network growth, and extension to the interfacial bonding layer between the adhesive layer and the substrate. This results in irreversible whitening and swelling of the residual adhesive layer, with a significant increase in volume. At the same time, water molecules penetrate into the interfacial bonding layer between the adhesive layer and the substrate through the expanded and extended nanoscale pore channels. They competitively adsorb and bind to polar groups on the substrate surface, replacing the hydrogen bonds and van der Waals forces between the original OCA adhesive layer and the substrate, thus significantly reducing the bonding stress of the interfacial bonding layer. Finally, the expanded and loose residual adhesive layer can be completely removed with only low-intensity physical peeling.

[0023] The entire process described above does not require high temperatures, highly corrosive solvents, or high-energy-consuming equipment. Furthermore, both anhydrous ethanol and water are low-toxicity and low-cost reagents, resulting in a light burden of waste liquid treatment and low overall implementation costs. At the same time, this cleaning method has high single-piece processing efficiency, making it suitable for the needs of continuous batch production lines. It is particularly applicable to the rework scenarios of high-precision optical components such as touch screens, foldable screens, and automotive display modules, and has good industrial practical value and promotion prospects. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart of a method for removing thermosetting OCA residue according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the workpiece and the residual adhesive layer in one embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of spraying anhydrous ethanol onto the residual adhesive layer on the surface of a workpiece in Embodiment 1 of the present invention, and then allowing it to stand.

[0028] Figure 4 This is a schematic diagram of an embodiment 1 of the present invention, in which water is sprayed onto the residual adhesive layer on the workpiece and then left to stand.

[0029] Figure 5 This is a schematic diagram of removing residual adhesive from a workpiece in Embodiment 1 of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0031] This invention provides a method for removing thermosetting OCA residue, which can completely remove thermosetting OCA residue while effectively protecting the integrity of the workpiece substrate and component structure. It also has the advantages of short process cycle, low reagent cost and light environmental impact, and is fully adaptable to the large-scale rework production scenarios of high-end optical components such as touch screens, foldable screens and automotive display modules.

[0032] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the present invention. Those skilled in the art can make appropriate adjustments, combinations, or modifications to the following technical solutions without departing from the concept of the present invention, and all such modifications should fall within the protection scope of the present invention.

[0033] like Figure 1 As shown, one embodiment of the present invention provides a method for removing thermosetting OCA residue, used to remove thermosetting OCA residue layers from workpieces. The removal method includes the following steps:

[0034] S1. Spray anhydrous ethanol onto the residual adhesive layer on the surface of the workpiece and let it stand for a first preset time to allow the residual adhesive layer to initially swell and form nanoporous channels inside. The first preset time is 30~120s.

[0035] S2. Spray water onto the surface of the initially swollen residual adhesive layer and let it stand for a second preset time to allow the water to penetrate into the interior of the residual adhesive layer along the nanopore channels, causing the residual adhesive layer to swell again and turn white as a whole, so as to reduce the adhesion between the residual adhesive layer and the workpiece. The second preset time is greater than or equal to 10s.

[0036] S3. Peel off the residual adhesive layer after the secondary swelling from the surface of the workpiece as a whole.

[0037] It is understood that the method for removing thermosetting OCA residue of the present invention, through a three-step synergistic mechanism of "initial swelling and pore creation with anhydrous ethanol - secondary swelling induced by water washing - physical overall peeling", can achieve rapid and thorough removal of thermosetting OCA residue without damaging the workpiece substrate.

[0038] It should be noted that thermosetting OCA, after curing, forms a cross-linked three-dimensional network structure. It is insoluble in water and does not easily swell with water, but it can be partially swelled by anhydrous ethanol. The adhesive force between it and the substrate (such as glass or PET film) mainly comes from van der Waals forces, hydrogen bonds, and a small amount of mechanical locking force.

[0039] In this method, anhydrous ethanol first independently penetrates into the gaps of the thermosetting OCA permanent cross-linked network, causing the residual adhesive layer to undergo initial uniform swelling. Within this layer, the original gaps are expanded into nanoscale pore channels, significantly weakening its cohesive strength. Subsequently, water is sprayed onto the surface of this initially swollen residual adhesive layer. This allows water molecules, which were previously difficult to penetrate the thermosetting OCA permanent cross-linked network, to enter the aforementioned nanoscale pore channels under the combined effects of ethanol-water miscibility and capillary action. These water molecules then associate with the ethanol molecules within the channels, forming larger alcohol-water associated clusters. These alcohol-water associated clusters generate a larger volume... The occupancy effect continuously compresses and expands the polymer chain segments of the cross-linked network, promoting pore expansion, network growth, and extension to the interfacial bonding layer between the adhesive layer and the substrate. This results in irreversible whitening and swelling of the residual adhesive layer, with a significant increase in volume. At the same time, water molecules penetrate into the interfacial bonding layer between the adhesive layer and the substrate through the expanded and extended nanoscale pore channels. They competitively adsorb and bind to polar groups on the substrate surface, replacing the original hydrogen bonds and van der Waals forces between the OCA adhesive layer and the substrate, thus significantly reducing the bonding stress of the interfacial bonding layer. Finally, only low-intensity physical peeling is required to remove the entire expanded and loose residual adhesive layer.

[0040] Furthermore, thermosetting OCA accumulates internal stress during curing due to cross-linking shrinkage and thermal expansion and contraction. Even after initial damage to the adhesive layer's integrity following disassembly, some stress remains within the residual adhesive layer. Water itself has a plasticizing effect; its entry into nanoscale pores further enhances the adhesive layer's flexibility, making it more susceptible to deformation under stress. Combined with the possibility of incompletely cross-linked oligomers or additives within the residual adhesive layer absorbing water and causing slight volume expansion, this further exacerbates the uneven stress distribution within the adhesive layer. When this stress accumulates to a certain level, coupled with the disruptive effect of water on the interface, the residual adhesive layer treated by the method described in this invention more easily bounces off the substrate and detaches effortlessly.

[0041] The workpiece, also known as the substrate, can be made of materials selected based on the specific application. For example, the workpiece can be optical-grade films or sheets such as glass (e.g., soda-lime glass, aluminosilicate glass), PET (polyethylene terephthalate), PC (polycarbonate), PMMA (polymethyl methacrylate), and PI (polyimide). Since thermosetting OCA is mainly used for full lamination and bonding between screens and protective covers, touch modules and display modules, or between various optical film layers, the workpiece is typically any one or a combination of substrate layers in the aforementioned bonding structure, with a residual thermosetting OCA adhesive layer adhering to its surface. The removal method of this invention has good adaptability to all types of workpiece materials and does not damage the workpiece surface during the removal process.

[0042] In one specific embodiment, the thermosetting OCA is the mainstream acrylate thermosetting OCA currently used in the display device field. This type of acrylate thermosetting OCA molecule contains polar groups, has a moderate crosslinking density, and excellent compatibility with anhydrous ethanol. It can be adapted to the stepwise pore-forming, secondary swelling, and interface debonding removal mechanism of this invention, and can achieve rapid and non-destructive overall peeling of residual adhesive.

[0043] like Figure 2 As shown, the thermosetting OCA residue includes a cross-linked network layer A near the free surface and an interfacial adhesive layer B tightly bonded to the workpiece C to be de-adhesiveted. The average size of the inherent cross-linked pores in the cross-linked network layer A is typically 2-5 nm (depending on the OCA system used). Since the kinetic equivalent diameter of anhydrous ethanol molecules (approximately 0.4 nm) is smaller than the inherent cross-linked pore size of the cross-linked network layer, after a first preset period of anhydrous ethanol immersion, anhydrous ethanol molecules can penetrate into the interior of the surface of the cross-linked network layer A through Brownian motion via these cross-linked pores, gradually opening and connecting multiple cross-linked pores from the surface to the interior, forming nanoporous channels that allow subsequent water molecules to enter.

[0044] It should be noted that, in the embodiments of the present invention, anhydrous ethanol mainly penetrates into the shallow and middle layers of the residual adhesive layer within a first preset standing time, widening the gaps in the cross-linked network in this region into nanoscale pore channels. Due to the limitations of cross-linking density and diffusion time, anhydrous ethanol usually cannot directly reach the interface bonding layer between the adhesive layer and the substrate, but the formed nanoscale pore channels provide a continuous path for the subsequent deep penetration of water molecules.

[0045] Since anhydrous ethanol and water are infinitely miscible, when water is sprayed onto the surface of the residual adhesive treated with anhydrous ethanol, after a second preset penetration time, water molecules, with the help of the miscibility of anhydrous ethanol and the capillary effect of the nanoporous channels, enter the cross-linked network layer along the formed nanoporous channels, and are further transported to the interfacial bonding layer. In this process, water molecules first enter the shallow part of the cross-linked network layer through the nanoporous channel entrance opened by the pre-wetting of anhydrous ethanol, and associate with ethanol molecules in the channel to form larger alcohol-water associated clusters. These alcohol-water associated clusters generate a volume occupation effect, continuously squeezing and expanding the polymer chain segments of the cross-linked network, promoting pore size expansion, network growth, and extension to the interfacial bonding layer between the adhesive layer and the substrate. The pore size widening and network growth of the nanoporous channels, in turn, enhance the capillary transport capacity of the nanoporous channels, further guiding the continuous input of more alcohol-water associated clusters, promoting the pore size widening and network expansion of each nanoporous channel in the thickness direction. Ultimately, the cross-linked network layer and interfacial adhesive layer of the thermosetting OCA residue are uniformly distributed with nanoporous channels containing alcohol-water associated clusters. Water molecules penetrate into the interfacial adhesive layer between the adhesive layer and the substrate through the expanded nanoporous channels, and combine with the polar groups on the substrate surface through competitive adsorption, replacing the original hydrogen bonds and van der Waals forces between the OCA adhesive layer and the substrate, thus significantly reducing the bonding stress of the interfacial adhesive layer. Finally, the expanded loose adhesive layer can be completely removed by low-intensity physical peeling.

[0046] At the macroscopic level, the residual adhesive layer expands rapidly in volume and turns white overall, achieving complete detachment and separation between the interfacial adhesive layer and the substrate interface. Throughout the process, the residual adhesive remains in a continuous solid state without collapsing or liquefying, allowing operators to achieve complete separation of the residual adhesive from the workpiece substrate in a single peeling operation.

[0047] Furthermore, as alcohol-water associative clusters continuously form and are transported inward along the channel network, the concentration of anhydrous ethanol is gradually diluted by water. When it finally reaches the interfacial adhesive layer and contacts the substrate, it has dropped to a safe concentration range that will not cause corrosion to the substrate.

[0048] As explained above, in existing thermosetting OCA residue removal operations, water is usually only used as a physical cleaning medium for impurities on the workpiece surface after adhesive removal. It has virtually no penetrating effect on the thermosetting OCA crosslinking network and does not have the function of removing residue. Although anhydrous ethanol is often used in the OCA process to wipe uncured overflow or surface stains, it usually only uses its dissolving effect on organic impurities for surface cleaning. It only has a limited surface wetting effect on fully cured thermosetting OCA residue and cannot cause it to soften, swell, or detach on its own. Even if the wetting time is greatly extended, it can only cause slight swelling on the surface of the residue and cannot penetrate to the interfacial bonding layer, let alone achieve complete separation of the residue from the substrate.

[0049] Therefore, it is evident that those skilled in the art would find it difficult to foresee that the efficient removal of thermosetting OCA residues could be achieved solely or in combination using water and anhydrous ethanol. However, the method of this invention, through the synergistic effect of a two-step sequence of pre-penetration with anhydrous ethanol and subsequent water spraying, achieves efficient, clean, and complete removal of thermosetting OCA residues while protecting the workpiece substrate from damage. It combines the advantages of non-destructive treatment, high cleanliness, and high efficiency. In other words, this invention provides a combined treatment scheme of "preliminary swelling and pore creation with anhydrous ethanol—secondary swelling induced by water washing—physical overall removal," achieving synergistic technical results far exceeding the effects of single-reagent treatments.

[0050] Preferably, the thickness of the thermosetting OCA residue layer to which this removal method is applicable is 10~100μm. This thickness range typically covers the most common residue thicknesses encountered during the rework of touchscreens, foldable screens, and automotive display modules. Within this thickness range, ethanol can fully penetrate within 30~120s to form nanoporous channels, and water subsequently seeps into the interfacial adhesive layer along these channels, achieving complete removal of the residue. Preferably, the temperatures of anhydrous ethanol and water are 20~28℃, respectively.

[0051] The operating environment temperature for steps S1-S3 of this cleaning method can be 20-28°C, correspondingly, the temperatures of anhydrous ethanol and water are also 20-28°C. This temperature range represents the stable evaporation rate of anhydrous ethanol. Under these conditions, anhydrous ethanol can maintain sufficient liquid phase residence time to fully penetrate the residual adhesive, while avoiding excessively slow evaporation due to excessively low temperature, which would prolong the process cycle, or excessively rapid evaporation due to excessively high temperature, which would weaken the pre-wetting effect. The operating temperature range of water is consistent with that of anhydrous ethanol. Within this temperature range, water has low surface tension and good permeability, which is conducive to the rapid capillary ascent of water molecules along the nanopore channels and their full miscibility with anhydrous ethanol. At the same time, it avoids the significant acceleration of the evaporation rate of anhydrous ethanol or the generation of thermal stress on the substrate due to excessively high water temperature, or the decrease in the miscibility rate and the obstruction of capillary penetration due to excessively low water temperature. The control of the above temperature range ensures the stability and repeatability of the process window, which is beneficial for quality control and batch replication in industrial production.

[0052] Tests showed that the cross-linking pore size of the thermosetting OCA residue is 2~5nm, and the thickness of the thermosetting OCA residue is 10~100μm. When the ambient temperature is in the range of 20~28℃, the time required for anhydrous ethanol molecules to fully penetrate the cross-linking network layer through Brownian motion is measured to be ≥30s.

[0053] If the standing time is less than 30 seconds, the anhydrous ethanol only adheres to the surface of the cross-linked network layer of the residual adhesive and has not fully penetrated into the interior of the cross-linked network layer. The cross-linked pores from the surface to the depth are not fully opened and connected, and can only form a small number of nanopore channels that allow subsequent water molecules to enter. As a result, subsequent water spraying cannot achieve overall debonding of the residual adhesive, and the residual adhesive is very easy to break during peeling, making it difficult to remove completely. If the standing time exceeds 120 seconds, the following adverse effects will occur: At a temperature of 20~28℃, the anhydrous ethanol liquid film spread on the surface of thermosetting OCA residue is easily affected by factors such as air convection and substrate thermal conductivity in the actual operating environment and will continue to evaporate. After 120 seconds of immersion, the effective anhydrous ethanol concentration on the adhesive surface has decreased to about 10~13% (calculated by real-time monitoring of the intensity decay of the characteristic peak of ethanol on the surface of the residue using Fourier transform infrared spectroscopy surface attenuation total reflectance mode, and this value is the measured average value of the liquid film spread at room temperature of 20~28℃). The low concentration of anhydrous ethanol cannot continue to effectively weaken the interfacial forces of the colloid. In addition, the residual anhydrous ethanol can dissolve a small amount of incompletely cross-linked acrylate low molecular weight oligomers from the surface of thermosetting OCA residue. After air drying, irreversible white fog will form on the surface of the residue and the edge of the substrate, and long-term contact will cause matte damage to the surface of the substrate. It is worth noting that within the time range of 30 to 120 seconds, anhydrous ethanol always adheres to the surface of the thermosetting OCA residue in the form of a high-concentration liquid film, without directly exposing a large area to the substrate. Moreover, the contact time is far below the substrate's critical corrosion threshold of 180 seconds. Therefore, the upper limit of 120 seconds naturally leaves sufficient safety margin and will not cause surface corrosion or matte damage to conventional substrates.

[0054] Of course, the crosslinking pore size and residual adhesive thickness may vary for thermosetting OCA with different process systems. Therefore, the first preset time can be adjusted in real time according to the actual residual adhesive system, and is not limited to the specific values ​​mentioned above.

[0055] Preferably, the first preset time is 30~60s. Within this time range, anhydrous ethanol molecules have fully penetrated the cross-linked network layer and formed complete nanoporous channels, which is sufficient to ensure that water molecules can smoothly enter the residual adhesive to achieve overall expansion and debonding. At the same time, the shorter wetting time helps to shorten the processing cycle of a single product, improve the overall rework efficiency of the production line, and further reduce the loss of anhydrous ethanol volatilization and the potential contact risk to the substrate, resulting in better overall economic efficiency and process stability.

[0056] In this embodiment, the second preset time is greater than or equal to 10 seconds. A standing time greater than 10 seconds after water spraying ensures that water molecules can enter the shallow part of the cross-linked network layer through the nanopore channel inlet. After mixing with anhydrous ethanol to form an alcohol-water mixture, the mixture can be fully guided to the deep part of the cross-linked network layer under the capillary action of the nanopore channels. Simultaneously, the nanopore channels undergo continuous pore size widening and network growth extension, thereby achieving sufficient expansion of the residual adhesive and interfacial debonding. If the standing time is too short, water molecules have not fully penetrated into the interfacial bonding layer, the widening of the nanopore channels and network growth extension are insufficient, and the residual adhesive still retains a strong interfacial bond with the substrate, making it prone to breakage or residue during peeling.

[0057] Preferably, the second preset time is 10~30s. Within this time range, sufficient expansion and de-adhesion effect can be guaranteed, and the overall process cycle can be effectively controlled, taking into account both cleaning efficiency and operational reliability.

[0058] It should be noted that both the first and second preset durations are based on the timing when the residual adhesive area is completely covered by water or anhydrous ethanol spraying.

[0059] Furthermore, to avoid the spraying or spraying time affecting the actual pre-wetting effect of anhydrous ethanol on the crosslinking network layer, the time range from the start of spraying to the complete coverage of the residual adhesive area can be 1 to 10 seconds in the step of spraying anhydrous ethanol onto the workpiece.

[0060] Specifically, in step S1, the anhydrous ethanol is sprayed using low-pressure atomization spraying with a spraying pressure of 0.05~0.1MPa. This pressure range allows the anhydrous ethanol to uniformly cover the surface of the residual adhesive in the form of fine droplets, ensuring the uniformity of the liquid film distribution while avoiding unnecessary stress disturbances caused by excessive pressure leading to droplet splashing or impact on the residual adhesive layer.

[0061] Furthermore, the purity of the anhydrous ethanol used in this invention is preferably greater than or equal to 99.5% (volume percentage), which corresponds to the specifications of conventional analytical grade or industrial-grade high-purity anhydrous ethanol. It should be noted that anhydrous ethanol is a common term in the art and does not mean absolutely no water content, but rather that its water content is controlled at an extremely low level (i.e., purity not less than 99.5%). Ethanol at this purity level can ensure effective penetration and swelling of the thermosetting OCA crosslinking network.

[0062] In this embodiment, the water is deionized water. Using deionized water can prevent metal ions, microorganisms and particulate impurities contained in tap water or ordinary industrial water from seeping into the interior of the residual adhesive along with the water molecules. This prevents the above-mentioned impurities from depositing in the nanoporous channels, blocking the channels or forming secondary pollution at the interface between the residual adhesive and the substrate, thus ensuring the uniformity and cleanliness of the expansion and debonding process.

[0063] In one specific embodiment, the removal method of the present invention further includes the following step: using a cleaning component containing anhydrous ethanol to wipe the alcohol-water mixture off the surface of the workpiece after adhesive removal.

[0064] After the peeling operation, only a trace amount of diluted alcohol-water mixture remains on the workpiece surface. This step aims to quickly remove this residual liquid to avoid impurity accumulation or uneven appearance that may occur during natural evaporation. Specifically, a lint-free cloth is preferred for cleaning. Gently wiping the workpiece surface with a lint-free cloth soaked in anhydrous ethanol quickly achieves a high-cleanliness optical surface. After wiping, there is no white haze or adhesive residue, and no additional drying or plasma treatment process is required. The workpiece can directly enter the secondary bonding process after this step, effectively improving the overall efficiency and yield of the rework process.

[0065] The technical solution of the present invention and its beneficial effects will be described in detail below with reference to specific embodiments and comparative examples.

[0066] Test reagents: Anhydrous ethanol with a purity ≥ 99.5% and deionized water (25℃);

[0067] Thermosetting OCAs used in experiments: 3A cross-linked acrylate thermosetting OCA for automotive applications, thermosetting OCA for full-lamination of mobile phones, high-viscosity thermosetting OCA for industrial control screens, and low-modulus thermosetting OCA for optical lenses.

[0068] Test substrate types: aluminosilicate tempered optical glass, ordinary float glass, high-transparency PET optical film, and high-transparency PC outer cover plate for vehicles;

[0069] The testing instruments used for substrate surface cleanliness include:

[0070] Haze: Haze meter; Transmittance: Spectrophotometer; Roughness Ra: Roughness tester; Adhesion state: Visual inspection + microscopic observation;

[0071] General spraying parameters:

[0072] When spraying anhydrous ethanol onto the residual adhesive layer, a low-pressure atomization spraying method is used, with a spraying pressure of 0.08 MPa. The time from the start of spraying to complete coverage of the residual adhesive surface is 3 to 5 seconds (approximately 4 seconds in this embodiment); the purity of the anhydrous ethanol is ≥99.5%, and the temperature is 25°C.

[0073] When spraying deionized water onto the residual adhesive layer after initial swelling, use low-pressure atomization or spraying method, and the temperature of the deionized water is 25℃.

[0074] To simulate the residual adhesive layer formed after OCA adhesive film bonding and curing, all embodiments used the same method for obtaining the workpiece to be removed, so as to accurately evaluate the adhesive removal process and its effectiveness. The method for obtaining the workpiece to be removed includes the following steps:

[0075] (1) The test target is obtained by bonding the pre-set substrate with OCA adhesive film;

[0076] (2) High-pressure degassing treatment is performed on the test target to eliminate interlayer bubbles;

[0077] (3) The degassed test target is baked and cured. The baking and curing steps include: baking and curing at 60℃ for 30~60min;

[0078] (4) After baking and curing, the test workpiece is cooled to 25°C and kept at a constant temperature for 72 hours. Then, each substrate is separated along the bonding interface to obtain the workpiece to be de-adhesive with continuous residual adhesive. The thickness of the residual adhesive is 10~100μm.

[0079] Example 1

[0080] In this embodiment, the OCA film used is automotive 3A cross-linked acrylate thermosetting OCA, the substrate is aluminosilicate tempered optical glass, the baking and curing time of the test workpiece is 30 min, and the residual adhesive thickness is 30 μm.

[0081] The specific steps of the removal method are as follows:

[0082] like Figure 3 As shown, anhydrous ethanol is sprayed onto the residual adhesive layer on the surface of the workpiece, and then left to stand for 30 seconds after spraying.

[0083] like Figure 4 As shown, spray water onto the residual adhesive layer on the workpiece, and let it stand for 10 seconds after spraying to promote the overall whitening and expansion of the residual adhesive.

[0084] like Figure 5 As shown, the residual adhesive is pulled up from any side of the residual adhesive layer to obtain the workpiece after adhesive removal.

[0085] The above operations were performed at 25°C.

[0086] Adhesive removal effect:

[0087] Ease of use: The residual adhesive can be lifted and peeled off with minimal force by hand;

[0088] Peeling integrity: No adhesive fragments were removed during the peeling process, and the residual adhesive was completely peeled off.

[0089] Substrate surface cleanliness: The substrate board surface is completely transparent, with haze increment ΔH≤0.1%, light transmittance attenuation ΔT≤0.2%, and no corrosion or residual adhesive.

[0090] Example 2

[0091] In this embodiment, the OCA film used is a vehicle-mounted 3A cross-linked acrylate thermosetting OCA, the substrate is aluminosilicate tempered optical glass, the baking and curing time of the test workpiece is 60 min, and the residual adhesive thickness is 50 μm.

[0092] The specific steps of the removal method are as follows:

[0093] Spray anhydrous ethanol onto the residual adhesive layer on the workpiece surface, and let it stand for 90 seconds after spraying.

[0094] Spray water onto the residual adhesive layer on the workpiece, and let it stand for 20 seconds after spraying to allow the residual adhesive to turn white and expand.

[0095] Pull up the residual adhesive from either side of the residual adhesive layer to obtain the workpiece after adhesive removal.

[0096] The above operations were performed at 25°C.

[0097] Adhesive removal effect:

[0098] Ease of use: The residual adhesive can be lifted and peeled off with minimal force by hand;

[0099] Peeling integrity: No adhesive fragments were removed during the peeling process, and the residual adhesive was completely peeled off.

[0100] Substrate surface cleanliness: The substrate board surface is free of white haze, the haze increase ΔH ≤ 0.1%, the light transmittance decrease ΔT ≤ 0.2%, there is no corrosion, and only a small amount of adhesive threads are present at the edges.

[0101] Example 3

[0102] In this embodiment, the OCA film used is a thermosetting OCA for full-lamination of mobile phones, the substrate is ordinary float glass, the baking and curing time of the test workpiece is 60 minutes, and the residual adhesive thickness is 40 μm.

[0103] The specific steps of the removal method are as follows:

[0104] Spray anhydrous ethanol onto the residual adhesive layer on the workpiece surface, and let it stand for 120 seconds after spraying.

[0105] Spray water onto the residual adhesive layer on the workpiece, and let it stand for 30 seconds after spraying to allow the residual adhesive to turn white and expand.

[0106] Pull up the residual adhesive from either side of the residual adhesive layer to obtain the workpiece after adhesive removal.

[0107] The above operations were performed at 25°C.

[0108] Adhesive removal effect:

[0109] Ease of use: The residual adhesive can be lifted and peeled off with minimal force by hand;

[0110] Peeling integrity: No adhesive fragments were removed during the peeling process, and the residual adhesive was completely peeled off.

[0111] Substrate surface cleanliness: The substrate board surface is completely transparent, with haze increment ΔH≤0.1%, light transmittance attenuation ΔT≤0.2%, no corrosion, and a small amount of adhesive threads at the edges.

[0112] Example 4

[0113] In this embodiment, the OCA adhesive film used is a thermosetting OCA for full-lamination of mobile phones, and the substrate is a high-transparency PET optical film. The baking and curing time of the test workpiece is 30 minutes, and the residual adhesive thickness is 20 μm.

[0114] The specific steps of the removal method are as follows:

[0115] Spray anhydrous ethanol onto the residual adhesive layer on the workpiece surface, and let it stand for 40 seconds after spraying.

[0116] Spray water onto the residual adhesive layer on the workpiece, and let it stand for 20 seconds after spraying to allow the residual adhesive to turn white and expand.

[0117] Pull up the residual adhesive from either side of the residual adhesive layer to obtain the workpiece after adhesive removal.

[0118] The above operations were performed at 25°C.

[0119] Adhesive removal effect:

[0120] Ease of use: The residual adhesive can be lifted and peeled off with minimal force by hand;

[0121] Peeling integrity: No adhesive fragments were removed during the peeling process, and the residual adhesive was completely peeled off.

[0122] Substrate surface cleanliness: The substrate surface is completely transparent, with haze increment ΔH≤0.1%, light transmittance attenuation ΔT≤0.2%, and no defects such as corrosion, residual adhesive, swelling, or tensile damage.

[0123] Example 5

[0124] In this embodiment, the OCA film used is a high-viscosity thermosetting OCA for industrial control screens, and the substrate is aluminosilicate tempered optical glass. The baking and curing time of the test workpiece is 30 minutes, and the residual adhesive thickness is 60 μm.

[0125] The specific steps of the removal method are as follows:

[0126] Spray anhydrous ethanol onto the residual adhesive layer on the workpiece surface, and let it stand for 60 seconds after spraying.

[0127] Spray water onto the residual adhesive layer on the workpiece, and let it stand for 10 seconds after spraying to allow the residual adhesive to turn white and expand.

[0128] Pull up the residual adhesive from either side of the residual adhesive layer to obtain the workpiece after adhesive removal.

[0129] The above operations were performed at 25°C.

[0130] Adhesive removal effect:

[0131] Ease of use: The residual adhesive can be lifted and peeled off with minimal force by hand;

[0132] Peeling integrity: No adhesive fragments were removed during the peeling process, and the residual adhesive was completely peeled off.

[0133] Substrate surface cleanliness: The substrate board surface is completely transparent, with haze increment ΔH≤0.1%, light transmittance attenuation ΔT≤0.2%, and no corrosion or residual adhesive.

[0134] Example 6

[0135] In this embodiment, the OCA film used is a high-viscosity thermosetting OCA for industrial control screens, and the substrate is a high-transparency PC outer cover plate for automotive applications. The baking and curing time of the test workpiece is 60 minutes, and the residual adhesive thickness is 100 μm.

[0136] The specific steps of the removal method are as follows:

[0137] Spray anhydrous ethanol onto the residual adhesive layer on the workpiece surface, and let it stand for 100 seconds after spraying.

[0138] Spray water onto the residual adhesive layer on the workpiece, and let it stand for 20 seconds after spraying to allow the residual adhesive to turn white and expand.

[0139] Pull up the residual adhesive from either side of the residual adhesive layer to obtain the workpiece after adhesive removal.

[0140] The above operations were performed at 25°C.

[0141] Adhesive removal effect:

[0142] Ease of use: The residual adhesive can be lifted and peeled off with minimal force by hand;

[0143] Peeling integrity: No adhesive fragments were removed during the peeling process, and the residual adhesive was completely peeled off.

[0144] Substrate surface cleanliness: The substrate surface is not matte white, the haze increase ΔH≤0.1%, the light transmittance decrease ΔT≤0.2%, there is no corrosion or cracking, and only a small amount of adhesive threads are present at the edges.

[0145] Example 7

[0146] In this embodiment, the OCA film is a low-modulus thermosetting OCA for optical lenses, the substrate is ordinary float glass, the baking and curing time of the test workpiece is 60 minutes, and the residual adhesive thickness is 25 μm.

[0147] The specific steps of the removal method are as follows:

[0148] Spray anhydrous ethanol onto the residual adhesive layer on the workpiece surface, and let it stand for 40 seconds after spraying.

[0149] Spray water onto the residual adhesive layer on the workpiece, and let it stand for 30 seconds after spraying to allow the residual adhesive to turn white and expand.

[0150] Pull up the residual adhesive from either side of the residual adhesive layer to obtain the workpiece after adhesive removal.

[0151] The above operations were performed at 25°C.

[0152] Adhesive removal effect:

[0153] Ease of use: The residual adhesive can be lifted and peeled off with minimal force by hand;

[0154] Peeling integrity: No adhesive fragments were removed during the peeling process, and the residual adhesive was completely peeled off.

[0155] Substrate surface cleanliness: The substrate surface is completely transparent, with haze increment ΔH≤0.1%, light transmittance attenuation ΔT≤0.2%, and no corrosion, no residual adhesive, and no solvent precipitation.

[0156] Example 8

[0157] In this embodiment, the OCA film is a low-modulus thermosetting OCA for optical lenses, the substrate is a high-transparency PC outer cover plate for vehicles, the baking and curing time of the test workpiece is 30 minutes, and the residual adhesive thickness is 10 μm.

[0158] The specific steps of the removal method are as follows:

[0159] Spray anhydrous ethanol onto the residual adhesive layer on the workpiece surface, and let it stand for 120 seconds after spraying.

[0160] Spray water onto the residual adhesive layer on the workpiece, and let it stand for 20 seconds after spraying to allow the residual adhesive to turn white and expand.

[0161] Pull up the residual adhesive from either side of the residual adhesive layer to obtain the workpiece after adhesive removal.

[0162] The above operations were performed at 25°C.

[0163] Adhesive removal effect:

[0164] Ease of use: The residual adhesive can be lifted and peeled off with minimal force by hand;

[0165] Peeling integrity: No adhesive fragments were removed during the peeling process, and the residual adhesive was completely peeled off.

[0166] Substrate surface cleanliness: The substrate board surface is completely transparent, with slight watermarks that can be wiped off, haze increase ΔH≤0.1%, light transmittance decrease ΔT≤0.2%, and no corrosion or residual adhesive.

[0167] Comparative Example 1

[0168] In this embodiment, the OCA film used is automotive 3A cross-linked acrylate thermosetting OCA, the substrate is automotive high-transparency PC outer cover plate, the baking and curing time of the test workpiece is 60 min, and the residual adhesive thickness is 50 μm.

[0169] The specific steps of the removal method are as follows:

[0170] Spray deionized water evenly onto the residual adhesive surface of the workpiece to be de-adhesiveed, let it stand for 5 minutes, and then perform the peeling operation on the residual adhesive surface.

[0171] The above operations were performed at 25°C.

[0172] Adhesive removal effect:

[0173] Ease of use: The adhesive residue is completely loose and cannot be peeled off.

[0174] Peel integrity: The residual adhesive cannot be peeled off at all;

[0175] Substrate surface cleanliness: The residual adhesive adhered firmly to the substrate surface, and no actual adhesive removal effect occurred.

[0176] Comparative Example 2

[0177] In this embodiment, the OCA film used is automotive 3A cross-linked acrylate thermosetting OCA, the substrate is automotive high-transparency PC outer cover plate, the baking and curing time of the test workpiece is 60 min, and the residual adhesive thickness is 50 μm.

[0178] The specific steps of the removal method are as follows:

[0179] A mixture of deionized water and anhydrous ethanol in a volume ratio of 1:1 is uniformly sprayed onto the residual adhesive surface of the workpiece to be de-adhesiveed. After standing for 2 minutes, the residual adhesive surface is peeled off.

[0180] The above operations were performed at 25°C.

[0181] Adhesive removal effect:

[0182] Ease of use: The adhesive residue cannot be completely removed and requires repeated wiping with force;

[0183] Peeling integrity: Only the shallow part of the residual adhesive can be peeled off, and a large amount of broken adhesive is generated during the peeling process;

[0184] Substrate surface cleanliness: The residual adhesive firmly adheres to the substrate surface, and the haze increase ΔH on the board surface is 0.62%, indicating slight haze contamination.

[0185] Comparative Example 3

[0186] In this embodiment, the OCA film used is automotive 3A cross-linked acrylate thermosetting OCA, the substrate is automotive high-transparency PC outer cover plate, the baking and curing time of the test workpiece is 60 min, and the residual adhesive thickness is 50 μm.

[0187] The specific steps of the removal method are as follows:

[0188] Spray anhydrous ethanol onto the residual adhesive layer on the workpiece surface, and let it stand for 150 seconds after spraying.

[0189] Spray water onto the residual adhesive layer on the workpiece, and let it stand for 20 seconds after spraying to allow the residual adhesive to turn white and expand.

[0190] Pull up the residual adhesive from either side of the residual adhesive layer to obtain the workpiece after adhesive removal.

[0191] The above operations were performed at 25°C.

[0192] Adhesive removal effect:

[0193] Ease of use: The adhesive residue cannot be completely removed and requires repeated wiping with force;

[0194] Peeling integrity: Localized residual adhesive peeling, with a large amount of broken adhesive generated during the peeling process;

[0195] Substrate surface cleanliness: Local residual adhesive adheres to the substrate surface, and irreversible white fog is generated on the board surface, with a fog increase ΔH=1.2%. The volatile and precipitated sol adheres to the board surface and is difficult to clean.

[0196] Comparative Example 4

[0197] In this embodiment, the OCA film used is automotive 3A cross-linked acrylate thermosetting OCA, the substrate is automotive high-transparency PC outer cover plate, the baking and curing time of the test workpiece is 60 min, and the residual adhesive thickness is 50 μm.

[0198] The specific steps of the removal method are as follows:

[0199] After uniformly spraying a commercial ketone-based strong corrosive adhesive remover onto the residual adhesive surface of the workpiece to be de-adhesiveed, the residual adhesive surface is wiped off.

[0200] The above operations were performed at 25°C.

[0201] Adhesive removal effect:

[0202] Ease of use: Unable to perform adhesive removal operation;

[0203] Peeling integrity: Peeling operation cannot be performed;

[0204] Substrate surface cleanliness: If the board cracks rapidly, turns white and loses its opacity, the substrate is directly scrapped and cannot be reused.

[0205] Comparative Example 5

[0206] In this embodiment, the OCA film used is automotive 3A cross-linked acrylate thermosetting OCA, the substrate is automotive high-transparency PC outer cover plate, the baking and curing time of the test workpiece is 60 min, and the residual adhesive thickness is 50 μm.

[0207] The specific steps of the removal method are as follows:

[0208] Spray anhydrous ethanol onto the residual adhesive layer on the workpiece surface, and let it stand for 25 seconds after spraying.

[0209] Spray water onto the residual adhesive layer on the workpiece, and let it stand for 20 seconds after spraying to allow the residual adhesive to turn white and expand.

[0210] Pull up the residual adhesive from either side of the residual adhesive layer to obtain the workpiece after adhesive removal.

[0211] The above operations were performed at 25°C.

[0212] Adhesive removal effect:

[0213] Ease of use: Requires repeated peeling and wiping with force;

[0214] Peeling integrity: Localized residual adhesive peeling, with a large amount of broken adhesive generated during the peeling process;

[0215] Substrate surface cleanliness: The substrate surface has localized residual adhesive, and the board surface has a slight white haze. The rework qualification rate is less than 20%.

[0216] Comparative Example 6

[0217] In this embodiment, the OCA film used is automotive 3A cross-linked acrylate thermosetting OCA, the substrate is automotive high-transparency PC outer cover plate, the baking and curing time of the test workpiece is 60 min, and the residual adhesive thickness is 50 μm.

[0218] The specific steps of the removal method are as follows:

[0219] A mixture of deionized water and anhydrous ethanol in a volume ratio of 1:9 is uniformly sprayed onto the residual adhesive surface of the workpiece to be de-adhesiveed. After standing for 2 minutes, the residual adhesive surface is peeled off.

[0220] The above operations were performed at 25°C.

[0221] Adhesive removal effect:

[0222] Ease of use: A small amount of residual adhesive can be removed after repeated wiping, but most of the residual adhesive cannot be completely peeled off;

[0223] Peeling integrity: Small areas of residual adhesive can be peeled off, but most residual adhesive can only be peeled off at a shallow level.

[0224] Substrate surface cleanliness: A large amount of residual adhesive firmly adheres to the substrate surface, and the haze increase ΔH=0.52% on the board surface indicates slight haze contamination.

[0225] As can be seen from the above embodiments, the method for removing thermosetting OCA residue provided by the present invention is applicable to major mainstream substrates and thermosetting OCA films in the field, and can achieve non-destructive, high-cleanliness, and single-piece overall peeling of thermosetting OCA residue under specific process parameters. In the adhesive removal effects shown in Examples 2, 3, 6, and 8, a small amount of adhesive threads are present at the edge of the substrate, or slight watermarks are present on the substrate surface. These trace adhesive threads can be removed by gently wiping with a lint-free cloth soaked in anhydrous ethanol, without affecting the yield of secondary bonding. The reason for this is that the baking and curing time of the test workpiece was relatively long, resulting in excessive cross-linking of the thermosetting OCA film on the edge of the substrate. Furthermore, the long pre-wetting time of anhydrous ethanol resulted in slightly more natural evaporation, slightly affecting the subsequent interaction with water. However, the substrate performance after adhesive removal still meets the mass production standards for secondary bonding.

[0226] To achieve better adhesive removal, a wetting time of 90-120 seconds is preferred for high-crosslinking, deeply cured OCA residue, and a wetting time of 30-60 seconds is preferred for low-crosslinking, shallowly cured OCA residue. The parameters can be flexibly matched to the crosslinking density of the adhesive layer.

[0227] In Comparative Example 1, the main resin of the thermosetting OCA is an acrylate polymer, which is hydrophobic and insoluble in water. It is also not easily swollen by water. Deionized water cannot penetrate into the cross-linked polymer network of the thermosetting OCA. Therefore, it cannot achieve any actual adhesive removal effect on the thermosetting OCA residue when used alone.

[0228] In Comparative Example 2, the alcohol-water mixture with a volume ratio of 1:1 of deionized water and anhydrous ethanol only caused slight local whitening of the thermosetting OCA residue, and the internal cohesion of the colloid was not destroyed. The reason is that the dynamic diameter of a single ethanol molecule is small, which can easily enter the cross-linking network pores of the thermosetting OCA. However, when ethanol and water coexist, the hydroxyl groups (-OH) in the ethanol molecules will form a large number of intermolecular hydrogen bonds with water molecules, causing ethanol molecules and water molecules to associate with each other and form larger alcohol-water associated clusters. In Comparative Example 2, the pre-mixed alcohol-water solution forms alcohol-water associated clusters before contacting the residual adhesive. The hydrodynamic size of the associated clusters is larger than that of a single ethanol molecule, which generates significant mass transfer steric hindrance at the pore entrance of the thermosetting OCA crosslinking network. This reduces the diffusion flux of the solvent into the pores, making it difficult to effectively open the original dense crosslinking pores. Only shallow swelling can occur, and water cannot be transported to the deep layers of the crosslinking network or the interfacial bonding layer. Therefore, it is impossible to effectively remove the thermosetting OCA residual adhesive.

[0229] In Comparative Example 3, the soaking time of anhydrous ethanol exceeded the upper limit of 120s specified in this invention, resulting in a large amount of anhydrous ethanol volatilizing during the soaking process. The lack of its effective components reduced its interaction with subsequent water, thus significantly reducing the loosening ability and causing severe fragmentation of the residual adhesive.

[0230] In Comparative Example 4, the ketones, halogenated hydrocarbons, and strong alkali components in the strong corrosive agent will damage the polyester molecular chain of the substrate, resulting in the absence of adhesive removal treatment for the thermosetting OCA residue on the substrate surface, thus rendering the substrate unusable.

[0231] In Comparative Example 5, the wetting time of anhydrous ethanol did not reach the lower limit of 30s specified in this invention. The anhydrous ethanol only adhered to the surface of the cross-linked network layer of the residual adhesive. The anhydrous ethanol molecules had not completely penetrated into the interior of the cross-linked network layer through the cross-linked pores. As a result, the multiple cross-linked pores from the surface to the interior were not fully opened and connected, and only a small number of nanoporous channels that could be formed for subsequent water molecules to enter were formed. This made it impossible for subsequent water spraying to achieve overall debonding of the residual adhesive, and the residual adhesive was very easy to break.

[0232] Comparative Example 6 and Comparative Example 2 are both alcohol-water mixtures, the difference being that the alcohol-water mixture provided in Comparative Example 6 has a higher concentration of anhydrous ethanol. The analysis corresponding to Comparative Example 2 mentioned above has already explained that "in the pre-mixed alcohol-water solution, ethanol and water molecules form alcohol-water associated clusters before contacting the residual adhesive. The hydrodynamic size of the associated clusters is larger than that of a single ethanol molecule, which generates significant mass transfer steric hindrance at the pore entrance of the thermosetting OCA crosslinking network, reducing the diffusion flux of the solvent into the pore interior, making it difficult to effectively open the original dense crosslinking pores, and only producing shallow swelling." That is, the pre-introduction of any amount of water will deteriorate the penetration of anhydrous ethanol into the thermosetting OCA residual adhesive layer and the opening of pore channels; in addition, a higher concentration of anhydrous ethanol means a lower concentration of water, and under the premise that the opening of pore channels is blocked in the early stage, a small amount of water is even more difficult to achieve the expansion and growth extension of pore channels.

[0233] It should be noted that in Comparative Example 6, the anhydrous ethanol concentration was relatively high. When sprayed onto the surface of the residual adhesive, the instantaneous effective concentration of ethanol in a local area might be sufficient to overcome the mass transfer steric hindrance of the associated clusters, generating a small number of nanoporous channels. These local pore channels provide a limited penetration path for water molecules in the alcohol-water mixture, allowing them to enter the interior of the residual adhesive and trigger local secondary swelling and interfacial debonding. Therefore, a small portion of the residual adhesive can be removed after repeated wiping. However, since the overall inhibitory effect of the alcohol-water associated clusters still exists, and the water content is low, the number, width, and depth of the pore channels are far less than those of the stepwise process of spraying ethanol first and then water in this invention. Therefore, it is impossible to achieve overall whitening, swelling, and complete peeling of the residual adhesive layer.

[0234] The test results and data from the above embodiments and comparative examples show that the present invention, through strict sequential control of pre-penetration with anhydrous ethanol followed by water spraying, can achieve efficient, clean, and complete removal of thermosetting OCA residue while protecting the substrate. The test results from the above embodiments and comparative examples also corroborate the aforementioned principle of removing thermosetting OCA residue with water and anhydrous ethanol.

[0235] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0236] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for removing thermosetting OCA residue, used to remove thermosetting OCA residue layers from workpieces, characterized in that, The removal method includes the following steps: Anhydrous ethanol is sprayed onto the residual adhesive layer on the surface of the workpiece and left to stand for a first preset time to allow the residual adhesive layer to initially swell and form nanoporous channels inside. The first preset time is 30~120s. Water is sprayed onto the surface of the initially swollen residual adhesive layer and left to stand for a second preset time, allowing the water to seep into the interior of the residual adhesive layer along the nanopore channels, causing the residual adhesive layer to swell a second time and turn white as a whole, so as to reduce the adhesion between the residual adhesive layer and the workpiece. The second preset time is greater than or equal to 10s. The residual adhesive layer after secondary swelling is peeled off the entire surface of the workpiece.

2. The method for removing thermosetting OCA residue according to claim 1, characterized in that, The thermosetting OCA is an acrylate thermosetting OCA.

3. The method for removing thermosetting OCA residue according to claim 1, characterized in that, The thickness of the residual adhesive layer is 10~100μm.

4. The method for removing thermosetting OCA residue according to claim 1, characterized in that, The first preset duration is 30~60s.

5. The method for removing thermosetting OCA residue according to claim 1, characterized in that, The second preset duration is 10~30s.

6. The method for removing thermosetting OCA residue according to claim 1, characterized in that, The ambient temperature during the cleaning method is 20~28℃; and / or, The temperatures of the anhydrous ethanol and the water are 20~28℃, respectively.

7. The method for removing thermosetting OCA residue according to claim 1, characterized in that, In the step of spraying anhydrous ethanol onto the residual adhesive layer on the workpiece surface, the time from the start of spraying to complete coverage of the residual adhesive is 1 to 10 seconds.

8. The method for removing thermosetting OCA residue according to claim 1, characterized in that, The anhydrous ethanol is applied by low-pressure atomization spraying, with a spraying pressure of 0.05~0.1MPa.

9. The method for removing thermosetting OCA residue according to claim 1, characterized in that, In the step of spraying water onto the surface of the pre-swollen residual adhesive layer, the water is deionized water.

10. The method for removing thermosetting OCA residue according to claim 1, characterized in that, The purity of the anhydrous ethanol is greater than or equal to 99.5%.

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