High-temperature-resistant acrylic acid protective film for Micro LED screen manufacturing process and preparation method of high-temperature-resistant acrylic acid protective film

Abstract

The invention relates to a high-temperature-resistant acrylic acid protective film for a Micro LED screen manufacturing process and a preparation method of the high-temperature-resistant acrylic acid protective film, and belongs to the technical field of protective films. The high-temperature-resistant acrylic acid protective film comprises a base material layer, a release layer arranged on the base material layer and a modified acrylic acid adhesive layer arranged between the base material layer and the release layer, the modified acrylic acid adhesive layer comprises the following components in parts by mass; 100 parts of acrylic resin, 5-15 parts of long-chain alkyl silicone oil, 0.5-2 parts of an epoxy curing agent and 0.1-0.5 part of an antistatic agent; on one hand, the long-chain alkyl silicone oil has excellent temperature resistance, the chain segment is soft, the infiltration capacity on the interface of a pasted object can be enhanced, and bubbles are effectively prevented from being generated between the protective film and the pasted object in a high-temperature environment; the problem of viscosity climbing under a high-temperature condition can be greatly inhibited, and a stable and reliable protection effect is provided for a Micro LED screen manufacturing process.

Description

Technical Field

[0001] This invention belongs to the field of protective film technology, and particularly relates to a high-temperature resistant acrylic protective film for Micro LED screen manufacturing process and its preparation method. Background Technology

[0002] With the continuous iteration and upgrading of display technology, Micro LED display technology, with its superior performance such as high brightness, high contrast, high response speed, long lifespan, and wide color gamut, has become the core development direction of next-generation display technology and is widely used in many high-end fields such as smart terminals, automotive displays, and large commercial displays. In the precision manufacturing process of Micro LED screens, the substrate, as the core carrier component, directly determines the surface treatment quality of subsequent chip packaging and overall display performance. To ensure the insulation performance of the substrate, prevent moisture and impurities from corroding, and improve device stability, it is usually necessary to deposit silicon nitride (Si3N4) or silicon oxide (SiO2) thin films on the substrate surface through processes such as chemical vapor deposition to form an insulating layer or passivation layer. This process places stringent requirements on the protection of the substrate surface.

[0003] In the deposition, cutting, and handling processes of Micro LED substrates, protective films are used to temporarily protect the substrate surface from scratches and contamination, while ensuring process accuracy. However, the Micro LED manufacturing process involves multiple high-temperature steps, requiring the protective films used to possess excellent high-temperature resistance. Currently, the most widely used protective films on the market are mainly divided into two categories: silicone-based protective films and acrylic-based protective films. However, both have significant drawbacks when applied to the high-temperature processes of Micro LED screens.

[0004] While silicone-based protective films possess certain high-temperature resistance and are widely used in the low- and medium-temperature processes of conventional electronic component manufacturing, the molecular structure of silicone is similar to that of the silicon nitride coating on the surface of Micro LED substrates. This leads to intermolecular interactions and adsorption between the two at high temperatures. When the silicone protective film is removed after the high-temperature process, a silicone adhesive layer is easily left on the substrate surface. This residual adhesive layer is difficult to remove completely using conventional cleaning processes and can directly cover the conductive lines or chip soldering sites on the substrate surface. This can cause problems such as poor contact and short circuits during subsequent Micro LED chip packaging, severely impacting product yield and even leading to the scrapping of entire batches of substrates, significantly increasing production costs.

[0005] Acrylic protective films suffer from a core defect: insufficient high-temperature resistance. Limited by the thermal stability of their resin system, conventional acrylic protective films exhibit a significant increase in adhesion under the high-temperature processing conditions of Micro LEDs. This means the adhesion between the protective film and the substrate surface increases dramatically, making subsequent removal difficult and potentially damaging the silicon nitride / silicon oxide coating on the substrate surface due to excessive adhesion. Simultaneously, the high temperature environment causes small molecules within the acrylic adhesive to volatilize, forming bubbles that remain between the protective film and the substrate, disrupting the tight adhesion. More seriously, the solvent resistance and barrier properties of the acrylic adhesive decrease at high temperatures, making it prone to softening and seepage. The seeped components may chemically react with the silicon nitride / silicon oxide coating on the substrate surface or contaminate the substrate surface, thus affecting the uniformity and stability of subsequent deposition processes and significantly reducing the yield of Micro LED screens.

[0006] Therefore, developing a protective film with excellent high-temperature resistance, no adhesive residue at high temperatures, low adhesion creep rate, and good adhesion and tearability, especially considering the special high-temperature process environment in the Micro LED manufacturing field, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a high-temperature resistant acrylic protective film for Micro LED screen manufacturing processes and its preparation method. The conventional acrylic resin is modified with long-chain alkyl silicone oil. On one hand, the long-chain alkyl silicone oil itself possesses excellent temperature resistance and flexible chain segments, enhancing its wetting ability on the substrate interface and effectively preventing air bubbles from forming between the protective film and the substrate under high-temperature conditions. On the other hand, the surface energy of the modified acrylic resin is significantly reduced, greatly suppressing the stickiness creep problem under high-temperature conditions, thereby providing stable and reliable protection for Micro LED screen manufacturing processes.

[0008] The first objective of this invention is to provide a high-temperature resistant acrylic protective film for Micro LED screen manufacturing processes, comprising a substrate layer, a release layer disposed on the substrate layer, and a modified acrylic adhesive layer disposed between the substrate layer and the release layer; The modified acrylic adhesive layer comprises, by weight, 100 parts acrylic resin, 5-15 parts long-chain alkyl silicone oil, 0.5-2 parts epoxy curing agent, and 0.1-0.5 parts antistatic agent.

[0009] In one embodiment of the present invention, the acrylic resin has a solid content of 30%-40%, and is subjected to a shear rate of 100s at 25°C. -1The viscosity under the given conditions is 1000 mPa·s-3000 mPa·s, the weight-average molecular weight is 200,000-400,000, the acid value is 5 mg KOH / g-25 mg KOH / g, and the glass transition temperature is -60℃ to -35℃.

[0010] In one embodiment of the present invention, the long-chain alkyl silicone oil is an epoxy-functionalized long-chain alkyl silicone oil.

[0011] In one embodiment of the present invention, the epoxy curing agent is selected from one or more of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, and pentaerythritol glycidyl ether.

[0012] In one embodiment of the present invention, the antistatic agent is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and / or lithium bis(trifluoromethanesulfonyl)imide.

[0013] In one embodiment of the present invention, the substrate layer is a polyimide film.

[0014] In one embodiment of the present invention, the release layer is a polyethylene terephthalate (PET) film.

[0015] In one embodiment of the present invention, the thickness of the substrate layer is 12μm-75μm; And / or, the thickness of the modified acrylic adhesive layer is 5μm-80μm; And / or, the thickness of the release layer is 12μm-125μm, and the release force is 10g / 25mm-30g / 25mm.

[0016] A second objective of this invention is to provide a method for preparing the high-temperature resistant acrylic protective film for Micro LED screen manufacturing processes, comprising the following steps: S1. Mix acrylic resin with long-chain alkyl silicone oil, add solvent until the solid content of the system is 24%-26%, stir at 60℃-90℃ for 28min-32min, and cool to obtain modified acrylic prepolymer; S2. Mix the modified acrylic prepolymer, epoxy curing agent and antistatic agent described in S1, add solvent until the solid content of the system is 19%-21%, stir evenly to obtain the modified acrylic adhesive. S3. The modified acrylic adhesive described in S2 is applied to the substrate layer, dried, and then laminated with a release film. After curing, the high-temperature resistant acrylic protective film for Micro LED screen manufacturing process is obtained.

[0017] In one embodiment of the present invention, the solvent is selected from one or more of ethyl acetate, toluene, and butyl acetate.

[0018] In one embodiment of the present invention, the drying temperature is 80°C-140°C.

[0019] In one embodiment of the present invention, the curing temperature is 40℃-50℃ and the time is 60h-84h.

[0020] The technical solution of the present invention has the following advantages compared with the prior art: The high-temperature resistant acrylic protective film of this invention is achieved by reacting epoxy-terminated long-chain siloxanes with carboxylic acid to graft acrylic resin and long-chain siloxanes. This process leverages the excellent temperature resistance and flexible segments of the long-chain siloxanes to enhance the wetting ability of the substrate interface, effectively preventing bubble formation at 240°C. It also significantly reduces the surface energy of the material, greatly suppressing the increase in adhesion after high temperatures. Simultaneously, the acrylic skeleton provides higher rigidity and mechanical strength, reducing the risk of residual adhesive on the SiN-coated substrate surface at high temperatures. Furthermore, it has the advantages of no adhesive residue after laser cutting and easy peeling, providing stable and reliable protection for Micro LED screen manufacturing processes. Attached Figure Description

[0021] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is the original state of the ink before the protective film was applied in this invention; Figure 2 This is the state of the protective film after the high-temperature process in Embodiment 2 of the present invention; Figure 3 This is the state of the present invention after the high-temperature process of bonding the protective film of Comparative Example 8; Figure 4 This is the state of the protective film of Comparative Example 9 after being bonded to the protective film of the present invention during the high-temperature process. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0023] In this invention, unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] In this invention, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] In this invention, unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0026] In this invention, unless otherwise stated, the acrylic resin used in the embodiments of this invention was purchased from Sanhe, model SR09170, with a solid content of approximately 37±2%, and was tested at 25°C and a shear rate of 100s. -1 The viscosity under the given conditions is 2000 mPa·s-3000 mPa·s, the weight-average molecular weight is 300,000-400,000, the acid value is 8 mg KOH / g-15 mg KOH / g, and the glass transition temperature is -60℃ to -40℃.

[0027] In this invention, unless otherwise stated, the long-chain alkyl silicone oil used in the embodiments of this invention is an epoxy-functionalized long-chain alkyl silicone oil, purchased from Ziyue, model KF-1001.

[0028] In this invention, unless otherwise stated, the epoxy curing agent used in the embodiments of this invention is N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane.

[0029] In this invention, unless otherwise stated, the antistatic agent used in the embodiments of this invention is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt.

[0030] In this invention, unless otherwise stated, the CAS number of the plasticizer TEG-DIO used in the comparative examples of this invention is 94-28-0.

[0031] In this invention, unless otherwise stated, the CAS number of the plasticizer DOTP used in the comparative examples of this invention is 6422-86-2. Example 1

[0032] The high-temperature resistant acrylic protective film for Micro LED screen manufacturing process in this embodiment includes a substrate layer, a release layer disposed on the substrate layer, and a modified acrylic adhesive layer disposed between the substrate layer and the release layer. The substrate layer is a polyimide film with a thickness of 25 μm; The thickness of the modified acrylic adhesive layer is 20 μm; The release layer is a PET monosilicone film with a thickness of 50μm and a release force of 20g / 25mm; The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 5 parts long-chain alkyl silicone oil, 1 part epoxy curing agent, and 0.25 parts antistatic agent.

[0033] Its preparation specifically includes the following steps: S1. Mix acrylic resin with long-chain alkyl silicone oil, add ethyl acetate until the solid content of the system is 24%-26%, stir at 60℃-90℃ for 28min-32min, cool to below 30℃ to obtain modified acrylic prepolymer; S2. Mix the modified acrylic prepolymer, epoxy curing agent and antistatic agent from S1, and solvent with ethyl acetate until the solid content of the system is 19%-21%. Stir evenly to obtain the modified acrylic adhesive. S3. The modified acrylic adhesive from S2 is coated onto the substrate layer, dried at 120°C, and then laminated with a release film. After winding, it is cured at 45°C for 70 hours to obtain a high-temperature resistant acrylic protective film for Micro LED screen manufacturing. Example 2

[0034] The process is basically the same as in Example 1, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 10 parts long-chain alkyl silicone oil, 1 part epoxy curing agent, and 0.25 parts antistatic agent. Example 3

[0035] The process is basically the same as in Example 1, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 15 parts long-chain alkyl silicone oil, 1 part epoxy curing agent, and 0.25 parts antistatic agent. Example 4

[0036] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 5 parts long-chain alkyl silicone oil, 1.5 parts epoxy curing agent, and 0.25 parts antistatic agent. Example 5

[0037] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 5 parts long-chain alkyl silicone oil, 2 parts epoxy curing agent, and 0.25 parts antistatic agent. Example 6

[0038] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 5 parts long-chain alkyl silicone oil, 1 part epoxy curing agent, and 0.1 parts antistatic agent. Example 7

[0039] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 5 parts long-chain alkyl silicone oil, 1 part epoxy curing agent, and 0.5 parts antistatic agent. Example 8

[0040] The process is basically the same as in Example 2, except that the thickness of the polyimide film is 12.5 μm. Example 9

[0041] The process is basically the same as in Example 2, except that the thickness of the polyimide film is 75 μm. Comparative Example 1

[0042] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 3 parts long-chain alkyl silicone oil, 1 part epoxy curing agent, and 0.25 parts antistatic agent. Comparative Example 2

[0043] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 1 part long-chain alkyl silicone oil, 1 part epoxy curing agent, and 0.25 parts antistatic agent. Comparative Example 3

[0044] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 18 parts long-chain alkyl silicone oil, 1 part epoxy curing agent, and 0.25 parts antistatic agent. Comparative Example 4

[0045] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 10 parts long-chain alkyl silicone oil, 0.3 parts epoxy curing agent, and 0.25 parts antistatic agent. Comparative Example 5

[0046] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 10 parts long-chain alkyl silicone oil, 2.5 parts epoxy curing agent, and 0.25 parts antistatic agent. Comparative Example 6

[0047] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 10 parts long-chain alkyl silicone oil, 1 part epoxy curing agent, and 0 parts antistatic agent. Comparative Example 7

[0048] The process is basically the same as in Example 2, except for the composition and amount of the modified acrylic adhesive layer, as detailed below: The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 10 parts long-chain alkyl silicone oil, 1 part epoxy curing agent, and 0.8 parts antistatic agent. Comparative Example 8

[0049] The basic structure is the same as in Example 2, except that the long-chain alkyl silicone oil in the modified acrylic adhesive layer is replaced with the plasticizer TEG-DIO (highly polar). Comparative Example 9

[0050] The basic structure is the same as in Example 2, except that the long-chain alkyl silicone oil in the modified acrylic adhesive layer is replaced with the plasticizer DOTP (weak polarity). Test Example 1

[0051] The high-temperature resistant acrylic protective films prepared in Examples 1-9 and Comparative Examples 1-9 were subjected to tests such as adhesion. (1) Initial adhesion: The test was conducted according to GB / T 2792-1998. A sample with a width of 25 mm was selected. The sample was attached to the Glass surface according to the test conditions and operation procedures specified in the standard. After standing for 30 minutes, the sample was peeled off at 300 mm / min using a tensile testing device. The force value generated during the peeling process was recorded. (2) Adhesion after aging: After aging at 230℃ for 2 hours and naturally cooling for 30 minutes, the adhesion after aging was tested according to GB / T 2792-1998 standard; (3) Adhesive surface impedance: The test is conducted in accordance with GB / T 33398-2016 standard to ensure that the adhesive surface is clean and free of impurities. The SIMCO ST-4 impedance tester is used to make effective contact between the test probe and the adhesive surface. The corresponding test conditions are applied according to the instrument operation specifications, and the impedance value of the adhesive surface is read and recorded. The result is in Ω and is used to evaluate the antistatic performance of the protective film adhesive surface. (4) Residual adhesive: The sample was bonded to the surface of the Micro LED substrate. The bonded component was placed in an environment of 230°C and kept at a constant temperature for 3 hours. After the high temperature treatment was completed, the component was cooled to room temperature and the protective film was peeled off. The surface of the Micro LED substrate was observed under a microscope at 400x magnification to determine whether there was any adhesive residue on the protective film under the high temperature bonding conditions. (5) High temperature bubble condition: Take a sample and attach it to the Micro LED substrate. Place the attached assembly in a high temperature environment of 230°C for 3 hours. After the high temperature treatment, cool it to room temperature. Visually observe whether bubbles are generated between the protective film and the Micro LED substrate. The test results are determined based on whether there are bubbles. (6) Adhesion: The test is conducted according to the cross-cut adhesion test method of ISO 2409-2007. A cross-cut adhesion tester is used to score the adhesive bonding area of ​​the sample. During the scoring process, the blade is made to penetrate the adhesive layer to the substrate surface to form a grid array of the specified number and size. Then, adhesive tape is tightly attached to the scored area and quickly peeled off. The peeling of the adhesive layer in the grid is observed, and the adhesion level is evaluated according to the standard rating standard. (7) High temperature holding force: The test was carried out in accordance with GB / T 4851-2014 standard. The 25mm wide sample was attached to the standard holding force test steel plate. A 2kg pressure roller was used to roll back and forth 3 times at a speed of 300mm / min. Then the sample with the protective film attached was vertically suspended in the 80℃ holding force oven. After standing for 20 minutes, a 1kg weight was suspended at the end of the protective film. The time required for the protective film to be completely peeled off from the test plate was recorded. (8) Appearance of adhesive surface: The test is conducted by visual observation. Under sufficient and uniform light conditions, the adhesive surface of the sample is directly observed to check whether there are any abnormal phenomena such as whitening, impurities, scratches, unevenness, etc. The results of the observation are used to determine whether it meets the requirements. (9) Ink: The sample was brought into contact with ink (75wt% methyl ethyl ketone, 5wt% cyclopentanone, 4wt% butyl acetate, 16wt% titanium dioxide). After being treated under the specified conditions, the surface condition of the ink was observed using a 400x microscope. The focus was on checking whether the ink showed obvious swelling, blurring or other defects. The compatibility between the protective film and the ink was judged based on the observation results. No obvious swelling or blurring was considered qualified (OK). Figures 1-4 Table 1 shows the number of relevant results for the final measured materials: Table 1

[0052] from Figures 1-4As can be seen from Table 1, the high-temperature resistant acrylic protective film of the embodiment has better heat resistance while possessing good initial tack, high-temperature tack ramp-up characteristics, low surface resistance and excellent adhesion. It can achieve the application effect of no bubbles and no adhesive residue in high-temperature environment, and has no obvious swelling effect on ink.

[0053] Comparing Example 2 and Comparative Examples 1-2, it can be seen that after reducing the amount of epoxy-functionalized end-capped long-chain alkyl silicone oil, the tackiness of the material after aging shows a significant upward trend (the tackiness of Comparative Example 2 after aging far exceeds the specified value), and the high-temperature bubble test results are all NG. This is because when the amount of epoxy-functionalized end-capped long-chain alkyl silicone oil is insufficient, its modification effect on acrylic resin is weakened. On the one hand, it cannot effectively reduce the surface energy of the material, leading to an aggravated increase in tackiness at high temperatures; on the other hand, insufficient long-chain siloxane segments result in poor wetting ability of the material to the interface of the substrate, increasing the gap between the protective film and the substrate during room temperature bonding. Under high-temperature conditions, the gas in the gap cannot be discharged in time, thus forming a high-temperature bubble phenomenon, which cannot meet the high-temperature use requirements of Micro LED manufacturing processes.

[0054] Comparing Example 2 and Comparative Example 3, it can be seen that when the amount of epoxy-functionalized end-capped long-chain alkyl silicone oil added is excessive, the initial viscosity of the material decreases significantly, and the viscosity after aging is only 20.77 g / 25 mm. Simultaneously, high-temperature residue occurs, the adhesive surface turns white, and the adhesion drops to 3B. This is because excessive addition of epoxy-functionalized end-capped long-chain alkyl silicone oil prevents complete reaction with the acrylic resin during prepolymerization, leading to an increase in free silicon components in the system. Free silicon components not only weaken the adhesive's viscosity, causing it to drop beyond application specifications, potentially resulting in poor adhesion between the protective film and the substrate and chip detachment in actual use; but also, during high-temperature baking, these unreacted free silicon components remain on the substrate surface, affecting the bonding force between the adhesive layer and the substrate, failing to meet the stringent requirements of residue-free and high-adhesion in Micro LED substrate manufacturing processes.

[0055] Comparing Example 2 and Comparative Example 4, it can be seen that after reducing the amount of epoxy curing agent added, the high-temperature residual adhesive test result of the material is NG, the viscosity after aging is 74.22g / 25mm, and the high-temperature holding power is only 24h. This is because when the addition ratio of epoxy curing agent is too low, it cannot fully react with acrylic resin and long-chain alkyl silicone oil, resulting in insufficient cohesion of the modified acrylic adhesive layer. Under high temperature conditions, the structural stability of the adhesive layer decreases, and the adhesive layer is prone to breakage when peeling off the protective film, thus generating residual adhesive on the substrate surface; at the same time, insufficient cohesion also causes a significant decrease in the high-temperature holding power of the material, making it unable to withstand the continuous high temperature of the Micro LED process, and the viscosity also abnormally increases due to insufficient cross-linking.

[0056] Comparing Example 2 and Comparative Example 5, it can be seen that when the amount of epoxy curing agent added is too high, the material exhibits both residual adhesive and high-temperature bubbles (both are NG), and the high-temperature holding power drops to 54 hours. This is because when the amount of epoxy curing agent added is excessive, it exceeds the reaction threshold of the system. The excess curing agent cannot continue to participate in the crosslinking reaction and remains in the adhesive layer in the form of small molecules. These small molecule residues not only cause abnormal fluctuations in viscosity at high temperatures, but also easily volatilize during high-temperature baking, forming gas and creating bubbles that remain between the protective film and the substrate. At the same time, the unreacted curing agent will damage the interfacial bonding between the adhesive layer and the substrate, causing residual adhesive problems during peeling, which seriously affects the process quality.

[0057] Comparing Example 2 and Comparative Example 6, it can be seen that after removing the antistatic agent, the surface resistance value of Comparative Example 6 is >10. 11 Ω. This is because the lack of antistatic agent causes the protective film to lose an effective electrostatic conduction channel, making it unable to release static electricity generated during the manufacturing process in a timely manner. Furthermore, the precision chips in Micro LED screens are extremely sensitive to static electricity; excessively high impedance can cause static electricity to accumulate on the substrate surface, easily damaging the screen chips during the customer's manufacturing process, resulting in product scrap and failing to meet the process protection requirements of high-end display devices.

[0058] Comparing Example 2 and Comparative Example 7, it can be seen that when the amount of antistatic agent added is too high, the high-temperature residue test result is NG, and the high-temperature retention capacity drops to 60h. This is because when the amount of antistatic agent added is excessive, it exceeds the load-bearing threshold of the adhesive layer. Under high-temperature conditions, the excess antistatic agent will migrate out of the adhesive layer in the form of small molecules. These migrated small molecules not only affect the structural integrity of the adhesive layer, leading to a decrease in cohesion and thus causing high-temperature residue, but also interfere with the interfacial bonding stability between the adhesive layer and the substrate, resulting in a decrease in high-temperature retention capacity and failing to meet the long-term high-temperature protection requirements of Micro LED manufacturing processes.

[0059] Comparing Example 2 and Comparative Examples 8-9, it can be seen that although the high-temperature peel strength of Comparative Examples 8-9 is reduced to some extent after replacing the epoxy-terminated long-chain siloxane with the high-polarity plasticizer TEG-DIO or the low-polarity plasticizer DOTP, there are still obvious defects: the high-temperature bubble problem is not solved, the ink compatibility test result is NG, the high-temperature holding power is only 2h, and the material cohesion is significantly worse. This is because plasticizers, as small molecule additives, can only reduce the surface energy of the material through trace migration to achieve a decrease in viscosity after high temperature. However, the migration of plasticizers will cause the ink substances to be corroded and swollen. Moreover, the amount of small molecule substances migrating out increases under high temperature conditions. On the one hand, the adhesive layer hardens due to the loss of plasticizers. On the other hand, the gas formed by the volatilization of small molecules remains between the protective film and the substrate, which in turn causes the high-temperature bubble phenomenon. Ultimately, it cannot meet the core requirements of the Micro LED screen manufacturing process for the protective film to be high-temperature resistant, non-corrosive, and highly stable.

[0060] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A high-temperature resistant acrylic protective film for Micro LED screen manufacturing process, characterized in that, It includes a substrate layer, a release layer disposed on the substrate layer, and a modified acrylic adhesive layer disposed between the substrate layer and the release layer; The modified acrylic adhesive layer, by weight, comprises: 100 parts acrylic resin, 5-15 parts long-chain alkyl silicone oil, 0.5-2 parts epoxy curing agent, and 0.1-0.5 parts antistatic agent.

2. The high-temperature resistant acrylic protective film for Micro LED screen manufacturing process according to claim 1, characterized in that, The acrylic resin has a solid content of 30%-40%, and is subjected to a shear rate of 100 s at 25°C. -1 The viscosity under the given conditions is 1000 mPa·s-3000 mPa·s, the weight-average molecular weight is 200,000-400,000, the acid value is 5 mg KOH / g-25 mg KOH / g, and the glass transition temperature is -60℃ to -35℃.

3. The high-temperature resistant acrylic protective film for Micro LED screen manufacturing process according to claim 1, characterized in that, The long-chain alkyl silicone oil is an epoxy-functionalized long-chain alkyl silicone oil.

4. The high-temperature resistant acrylic protective film for Micro LED screen manufacturing process according to claim 1, characterized in that, The epoxy curing agent is selected from one or more of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, and pentaerythritol glycidyl ether.

5. The high-temperature resistant acrylic protective film for Micro LED screen manufacturing process according to claim 1, characterized in that, The antistatic agent is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and / or lithium bis(trifluoromethanesulfonyl)imide.

6. The high-temperature resistant acrylic protective film for Micro LED screen manufacturing process according to claim 1, characterized in that, The substrate layer is a polyimide film.

7. The high-temperature resistant acrylic protective film for Micro LED screen manufacturing process according to claim 1, characterized in that, The release layer is a polyethylene terephthalate film.

8. The high-temperature resistant acrylic protective film for Micro LED screen manufacturing process according to claim 1, characterized in that, The thickness of the substrate layer is 12μm-75μm; And / or, the thickness of the modified acrylic adhesive layer is 5μm-80μm; And / or, the thickness of the release layer is 12μm-125μm, and the release force is 10g / 25mm-30g / 25mm.

9. The method for preparing a high-temperature resistant acrylic protective film for Micro LED screen manufacturing as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Mix acrylic resin with long-chain alkyl silicone oil, add solvent until the solid content of the system is 24%-26%, stir at 60℃-90℃ for 28min-32min, and cool to obtain modified acrylic prepolymer; S2. Mix the modified acrylic prepolymer, epoxy curing agent and antistatic agent described in S1, add solvent until the solid content of the system is 19%-21%, stir evenly to obtain the modified acrylic adhesive. S3. The modified acrylic adhesive described in S2 is applied to the substrate layer, dried, and then laminated with a release film. After curing, the high-temperature resistant acrylic protective film for Micro LED screen manufacturing process is obtained.

10. The method for preparing a high-temperature resistant acrylic protective film for Micro LED screen manufacturing process according to claim 9, characterized in that, The solvent is selected from one or more of ethyl acetate, toluene, and butyl acetate.

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