High-performance PO composite film for OMR vacuum transfer printing and preparation method of high-performance PO composite film

Abstract

The invention discloses a high-performance PO composite film for OMR vacuum transfer printing and a preparation method of the high-performance PO composite film, and belongs to the technical field of thermal transfer printing, and the preparation method comprises the following steps: carrying out plasma treatment on a PO base material, then sequentially coating a lower-layer coating, a middle-layer coating and an upper-layer coating, and curing after coating each time to form a cured Primer layer; the lower-layer coating is formed by coating liquid containing zinc acrylate, nano SiO2, a photoinitiator and a lower-layer solvent, the middle-layer coating is formed by slurry of epoxy resin, silicone rubber microspheres, a curing agent and a middle-layer solvent, and the upper-layer coating is formed by suspension liquid containing graphene aerogel microspheres; and sequentially stacking the PET layer, the PO layer, the cured Primer layer and the CPP / PE layer, performing hot-pressing compounding, and curing to obtain the PO composite film. According to the method, a gas escape channel and a chemical capture and physical adsorption barrier are cooperatively constructed through the three-stage coating, vacuum transfer printing bubbles are remarkably eliminated, and the pattern precision and the interlayer bonding strength are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal transfer, and in particular relates to a high-performance PO composite film for OMR vacuum transfer and a preparation method thereof. Background Art

[0002] In the field of optical mark recognition (OMR) technology, the vacuum transfer process is widely used in the manufacture of labels, logos and other products. Its core lies in the precise transfer of patterns through polymer functional films. In the existing technology, composite films usually adopt a multi-layer structure, including a polyethylene terephthalate (PET) protective layer, a polyolefin (PO) base layer and a cast polypropylene / polyethylene (CPP / PE) protective layer. These layers are integrated through a hot pressing composite process to provide mechanical support and transfer functions. However, this type of composite film is easily affected by the material interface characteristics and process parameters in a vacuum environment, resulting in unstable transfer efficiency, which limits its promotion in high-speed, high-precision application scenarios.

[0003] Furthermore, existing composite films face significant bubble problems during the vacuum transfer process: due to interfacial tension mismatch between film layers and residual solvent, microbubbles are easily formed during transfer. These bubbles expand or remain during the hot pressing stage, causing distortion of the transferred pattern, blurred edges, or partial loss. The bubble problem not only reduces product yield but also increases subsequent rework costs. Especially in precision OMR applications, the defects caused by bubbles will directly affect the accuracy of optical recognition. Although existing technologies attempt to alleviate bubbles by optimizing the coating process or adding additives, the defoaming effect is limited and cannot completely eliminate the generation and accumulation of bubbles in multi-layer composite structures.

[0004] Therefore, the key technical challenge that currently faces challenges with OMR vacuum transfer composite films is designing a high-performance film structure that effectively suppresses bubble formation in a vacuum environment, ensuring uniformity and reliability during the transfer process while maintaining the film's mechanical strength and production efficiency. Solving this problem will significantly improve transfer quality and meet the increasingly demanding demands of industrial applications. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for preparing a high-performance PO composite film for OMR vacuum transfer, comprising the following steps: S1, plasma-treating a PO substrate to obtain a pretreated PO substrate; S2, coating a lower coating on the pretreated PO substrate, wherein the lower coating is formed by a coating solution comprising zinc acrylate, nano-SiO2, a photoinitiator 184, and a lower solvent, and after coating, infrared drying and UV curing are performed to obtain a lower coating; S3, coating a middle coating on the lower coating, wherein the middle coating is formed by a coating solution comprising a phosphate-modified epoxy resin, silicone rubber microspheres, a methylhexahydrophthalic anhydride curing agent, and a middle solvent. Slurry is formed, and after coating, it is step-cured to obtain a middle coating; S4, an upper coating is sprayed on the middle coating, and the upper coating is formed by a suspension containing graphene aerogel microspheres. After spraying, it is dried and vacuum activated to obtain an upper coating; S5, the upper coating is post-cured, and the hot air circulation temperature is 125-135°C and the time is 80-100s to obtain a cured Primer layer consisting of a lower coating, a middle coating and an upper coating; S6, the PET layer, the PO layer, the cured Primer layer and the CPP / PE layer are stacked in sequence, hot-pressed and composited, and then aged to obtain the PO composite film.

[0006] In some embodiments, step S2 includes: S21, applying the coating liquid using a micro-gravure coater, with a screen count of 170-190 meshes and a wet film thickness of 9.5-10.5 μm; S22, infrared drying, with a drying temperature of 65-75°C and a drying time of 15-25 seconds; S23, UV curing, with an irradiation intensity of 110-130 mW / cm 2 , cumulative dose is 550~650mJ / cm 2 .

[0007] In some embodiments, in step S2, the coating solution comprises the following components in parts by mass: 90-110 parts by mass of zinc acrylate, 4-6 parts by mass of nano-SiO2, 2.0-3.0 parts by mass of photoinitiator, and 140-160 parts by mass of lower layer solvent.

[0008] In some embodiments, step S3 includes: S31, coating the slurry using a precision slit coater, the substrate speed is 1.8 to 2.2 m / min, and the wet film thickness is 27 to 29 μm; S32, step curing, including a pre-curing stage temperature of 75 to 85°C, time 2.5 to 3.5 min, a main curing stage temperature of 95 to 105°C, time 1.5 to 2.5 min, and a final curing stage temperature of 115 to 125°C, time 1.5 to 2.5 min.

[0009] In some embodiments, in step S3, the slurry comprises the following components in parts by mass: 95-105 parts by mass of phosphate-modified epoxy resin, 16-20 parts by mass of silicone rubber microspheres, 26-30 parts by mass of methylhexahydrophthalic anhydride curing agent, and 110-130 parts by mass of middle layer solvent.

[0010] In some embodiments, step S4 includes: S41, spraying the suspension using an ultrasonic electrostatic spraying system, with a spray gun voltage of +23 to +27 kV, a substrate bias of -4 to -6 kV, a flow rate of 7.2 to 8.8 mL / min, and an atomizing pressure of 0.11 to 0.13 MPa; S42, drying and activation, including infrared hot air drying at a temperature of 55 to 65°C, a drying time of 35 to 45 seconds, a vacuum activation pressure of -0.09 to -0.1 MPa, and an activation time of 20 to 30 seconds.

[0011] In some embodiments, in step S4, the suspension comprises 1.5-2.1 wt % of graphene aerogel microspheres, 0.2-0.4 wt % of a dispersant, 0.1-0.2 wt % of a wetting agent, and the balance is deionized water.

[0012] In some embodiments, step S4 further includes preparing the graphene aerogel microspheres: S43, mixing the graphene oxide dispersion and the polymethyl methacrylate microspheres in a mass ratio of 1:2.8 to 1:3.2, and performing alternating ultrasound-centrifugation treatment at an ultrasound frequency of 38 to 42 kHz and a centrifugal speed of 2800 to 3200 rpm for 2 to 4 cycles to obtain a self-assembled mixture; S44, pre-freezing the self-assembled mixture at -18 to -22°C for 1.5 to 2.5 hours, and then quick-freezing at -190 to -200°C for 8 to 12 minutes. Then cool from -5°C to -40°C at a cooling rate of 0.8-1.2°C / min to obtain a frozen molded body; S45, reduce the frozen molded body in hydroiodic acid, with a solution pH value of 2.5-3.5, a temperature of 50°C, and a time of 2 hours to obtain a reduced product; S46, dry the reduced product under supercritical CO2 conditions, with a pressure of 7.3-7.5MPa, a temperature of 30.5-31.5°C, a time of 3.5-4.5 hours, and a pressure release rate of 0.08-0.12MPa / min to obtain graphene aerogel microspheres.

[0013] In some embodiments, in the plasma treatment of step S1, the plasma gas is a mixture of He and O2, wherein the volume fraction of He is 85% to 95%, the volume fraction of O2 is 5% to 15%, and the power density of the plasma treatment is 0.7 to 0.9 W / cm 2, the processing pressure is atmospheric pressure, the processing speed is 2.5-3.5 m / min, and the inter-electrode spacing is 1.5-2.5 mm; in the step S6, the hot pressing temperature is 110-120°C, the hot pressing pressure is 0.7-0.9 MPa, the hot pressing time is 40-50 s, the hot pressing roller speed is 1.4-1.6 m / min, the aging temperature is 35-45°C, the aging time is 22-26 h, and the relative humidity of the aging environment is ≤30%.

[0014] The present application also provides a high-performance PO composite film for OMR vacuum transfer, which is obtained based on any of the aforementioned preparation methods.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. Through plasma treatment combined with zinc acrylate-nano-SiO2 composite coating, the surface energy of the PO substrate is increased to above 42mN / m, and at the same time, a through microporous channel of 0.1-0.5μm is formed, which reduces the probability of interface bubble nucleation from the source and reduces the coating defect rate.

[0017] 2. Through the synergy of chemical gas capture by phosphate-modified epoxy resin, elastic cushioning by silicone rubber microspheres, and physical adsorption by graphene aerogel, a dynamic defoaming barrier is formed between the middle and upper layers, and the edge offset of the vacuum transfer pattern is extremely low.

[0018] 3. Through the coordinated control of temperature and time of step curing and post-curing, the epoxy resin is completely cross-linked and the damage to the microsphere structure is avoided. At the same time, during hot pressing and compounding, the CPP / PE melt layer tightly covers the Primer structure, thereby enhancing the interlayer peeling strength.

[0019] 4. Through the optimization of electrostatic spraying parameters and vacuum activation pressure control, the graphene aerogel microspheres are evenly distributed and have a high porosity, the gas adsorption efficiency is improved, and zero bubble residue is guaranteed during the transfer process.

[0020] 5. Through sand grinding dispersion and vacuum degassing process, the silicone rubber microspheres are evenly dispersed and the air content is extremely low, eliminating coating stripe defects and ensuring the consistency of the coating surface. DETAILED DESCRIPTION

[0021] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0022] The present invention provides a method for preparing a high-performance PO composite film for OMR vacuum transfer, comprising the following steps:

[0023] S1. Plasma-treating a PO substrate to obtain a pretreated PO substrate;

[0024] S2, coating a lower coating on the pretreated PO substrate, wherein the lower coating is formed by a coating solution comprising zinc acrylate, nano-SiO2, a photoinitiator 184, and a lower solvent, and after coating, infrared drying and UV curing are performed to obtain a lower coating;

[0025] S3, coating a middle coating on the lower coating, wherein the middle coating is formed from a slurry comprising a phosphate-modified epoxy resin, silicone rubber microspheres, a methyl hexahydrophthalic anhydride curing agent, and a middle-layer solvent, and step-curing the coating to obtain a middle coating;

[0026] S4, spraying an upper coating layer on the middle coating layer, wherein the upper coating layer is formed by a suspension containing graphene aerogel microspheres, and drying and vacuum activating the upper coating layer after spraying to obtain the upper coating layer;

[0027] S5, post-curing the upper coating layer with hot air circulation at a temperature of 125-135° C. for 80-100 seconds to obtain a cured Primer layer consisting of a lower coating layer, a middle coating layer, and an upper coating layer;

[0028] S6. Stacking the PET layer, the PO layer, the cured Primer layer and the CPP / PE layer in sequence, performing hot pressing and lamination, and then aging to obtain the PO composite film.

[0029] The present invention solves the vacuum transfer bubble problem through the synergistic effect of three-level coating:

[0030] In S1-S2 of the present invention, a gas escape channel is established: plasma treatment introduces polar groups on the surface of the PO substrate to enhance the interfacial bonding strength; zinc acrylate is cured to form an ion cross-linked network, and nano-SiO2 modified with KH-570 constructs a 0.1-0.5 μm microporous channel in the coating, allowing the interfacial gas to escape preferentially during the infrared drying stage, thereby reducing the bubble nucleation sites from the source.

[0031] The present invention realizes dynamic elimination of bubbles in S3-S4: the P=O group of the phosphate-modified epoxy resin in the middle coating chemically captures gas molecules such as CO2 / H2O to form a stable phosphate compound; the silicone rubber microspheres absorb the expansion energy of the bubbles through elastic deformation, thereby inhibiting the growth of bubbles; the upper-layer graphene aerogel microspheres open the closed-pore structure through vacuum activation, and physically adsorb residual gas through the ultra-large specific surface area to form a three-level bubble capture barrier.

[0032] The present invention completes structural sealing in S5-S6: post-curing promotes complete cross-linking of the middle layer epoxy resin, sealing potential gas release sources; during hot pressing and compounding, the molten CPP / PE layer acts as a sealing layer to wrap the Primer structure, and the aging process causes the molecular chains between the layers to slowly relax, eliminating interfacial stress microcavities, and ultimately achieving bubble-free compounding through the synergistic effect of temperature, pressure and time.

[0033] The present invention combines a zinc acrylate-nano-SiO2 composite coating with a plasma treatment to improve the surface energy of the PO substrate and form a gas escape path, thereby reducing the probability of interface bubble nucleation from the source and significantly reducing the coating defect rate. Through the chemical capture of gas by the P=O group of the phosphate-modified epoxy resin, the elastic buffering expansion energy of the silicone rubber microspheres, and the physical adsorption synergy of the graphene aerogel microspheres, a three-level dynamic defoaming barrier is formed in the middle layer and the upper layer, eliminating the residual bubbles in the vacuum environment and ensuring that the edge clarity of the transfer pattern is improved. Through the synergistic effect of step curing and post-curing, the middle layer epoxy resin is completely cured and the microsphere structure is avoided from being damaged. At the same time, during hot pressing and compounding, the CPP / PE molten layer tightly covers the Primer structure, and the curing process releases the interlayer stress, achieving zero bubble residue at the composite film interface and improving the product yield. Through electrostatic spraying path optimization and vacuum activation pressure drop rate control, the graphene aerogel microspheres are evenly distributed and have a high porosity, maintaining a high specific surface area gas capture capacity and avoiding the coating failure caused by microsphere rupture. Through the sand grinding dispersion process and vacuum degassing, the silicone rubber microspheres in the middle layer slurry are evenly dispersed, the bubbles in the slurry itself are eliminated, and the coating process is guaranteed to be free of streak defects.

[0034] In some embodiments, step S2 includes:

[0035] S21, apply the coating liquid using a micro-gravure coater, with a screen count of 170-190 meshes and a wet film thickness of 9.5-10.5 μm;

[0036] S22, infrared drying, drying temperature is 65-75℃, drying time is 15-25s;

[0037] S23, UV curing, irradiation intensity is 110~130mW / cm 2 , cumulative dose is 550~650mJ / cm 2 .

[0038] The amount of coating liquid transferred is precisely controlled by a micro-gravure coater with a screen count of 170-190 meshes to form a uniform wet film layer of 9.5-10.5 μm. The coordinated design of the mesh density and thickness ensures the directional arrangement of nano-SiO2 in the zinc acrylate matrix, forming a continuous gas escape channel. Subsequently, infrared drying is performed at 65-75°C for 15-25 seconds to evaporate the isopropyl alcohol solvent, avoid local boiling and generate new bubbles, and at the same time retain the integrity of the 0.1-0.5 μm microporous structure. Finally, the coating is heated at 110-130 mW / cm 2 Irradiation intensity for UV curing, 550~650mJ / cm 2 The cumulative dose precisely triggers the decomposition of photoinitiator 184, prompting the rapid cross-linking of zinc acrylate to form an ionic bond network, achieving a balance between the curing rate and the interlayer permeability, fixing the microporous channels of nano-SiO2 while avoiding channel closure caused by excessive cross-linking, thereby establishing a stable and efficient gas diffusion path at the source and significantly reducing the risk of residual bubbles at the coating interface.

[0039] In some embodiments, in step S2, the coating solution comprises the following components by weight: 90-110 parts by weight of zinc acrylate, 4-6 parts by weight of nano-SiO2, 2.0-3.0 parts by weight of a photoinitiator, and 140-160 parts by weight of a lower layer solvent. In some embodiments, the photoinitiator is 1-hydroxycyclohexylphenyl ketone (photoinitiator 184), which has a cleavage wavelength range of 254-365 nm.

[0040] The main film-forming network is constructed by 90-110 parts by mass of zinc acrylate. 2+ ) forms a strong coordination bond with the plasma-treated PO substrate, and at the same time, 4-6 parts by mass of nano-SiO2 modified by KH-570 are uniformly dispersed in the coating to form 0.1-0.5μm microporous channels, while 2.0-3.0 parts by mass of photoinitiator 184 are efficiently decomposed in the 254-365nm band, triggering the rapid cross-linking of zinc acrylate to fix the microporous structure; 140-160 parts by mass of isopropyl alcohol solvent (boiling point 82.6℃) is precisely proportioned to control the solid content of 40.2±0.5%, and volatilizes during the infrared drying stage, which not only avoids bubbles caused by solvent residues, but also prevents micropore collapse; finally, a lower coating with both high adhesion and through-gas channels is formed, eliminating interfacial gas retention from the source and ensuring defect-free composite of subsequent coatings.

[0041] In some embodiments, the coating solution is prepared by the following method:

[0042] Mixing 90 to 110 parts by mass of zinc acrylate and 140 to 160 parts by mass of isopropyl alcohol, and stirring at a speed of 800 to 1200 rpm for 10 to 20 minutes to obtain a zinc acrylate solution;

[0043] Adding 4 to 6 parts by weight of nano-SiO2 to the zinc acrylate solution in portions, dispersing at a speed of 1000 to 1400 rpm for 3 to 5 minutes after each addition, controlling the temperature below 40° C., to obtain a primary mixed solution;

[0044] Add 2.0-3.0 parts by mass of photoinitiator 184 and 0.6-1.0 parts by mass of leveling agent BYK-333 to the primary mixed solution, and mix at a speed of 700-900 rpm for 4-6 minutes to obtain a dispersed slurry;

[0045] The dispersed slurry was subjected to ultrasonic treatment at an ultrasonic power of 550-650 W in a pulse mode (on for 1.5-2.5 s / off for 0.5-1.5 s) for 1.5-2.5 min to obtain a homogeneous slurry;

[0046] The homogenized slurry is filtered and sequentially passed through a nylon filter with a pore size of 90 to 110 μm and a metal sintered mesh with a pore size of 18 to 22 μm at a filtration pressure of 0.25 to 0.35 MPa to obtain a coating liquid.

[0047] The nano-SiO2 is treated with γ-(methacryloyloxy)propyltrimethoxysilane (KH-570), and microporous channels with a pore size of 0.1-0.5 μm are formed on the surface of the treated SiO2 for gas escape.

[0048] In some embodiments, step S3 includes:

[0049] S31, using a precision slit coater to apply the slurry, with a substrate speed of 1.8 to 2.2 m / min and a wet film thickness of 27 to 29 μm;

[0050] S32, step curing, including a pre-curing stage at a temperature of 75-85°C and a time of 2.5-3.5 minutes, a main curing stage at a temperature of 95-105°C and a time of 1.5-2.5 minutes, and a final curing stage at a temperature of 115-125°C and a time of 1.5-2.5 minutes.

[0051] In step S3, the slurry leveling time is controlled by a precision slit coater at a substrate speed of 1.8 to 2.2 m / min, and the coating volume is precisely controlled in combination with a wet film thickness of 27 to 29 μm, so that the phosphate-modified epoxy resin and the silicone rubber microspheres are evenly distributed, avoiding coating streaks and microsphere agglomeration.

[0052] A three-stage curing is further adopted: in the pre-curing stage, low-boiling-point solvents (such as propylene glycol methyl ether acetate) are preferentially volatilized and the pre-cross-linking of the resin is initiated; in the main curing stage, methyl hexahydrophthalic anhydride curing agent is activated to achieve deep cross-linking; and in the final curing stage, the resin network is densified under nitrogen protection. This temperature-time synergistic mechanism not only protects the elastic structure of the silicone rubber microspheres from being destroyed by high temperature, but also enables the phosphate groups to fully capture CO2 / H2O gas to form stable compounds, ultimately achieving a defoaming functional layer with no bubble residue and elastic buffering capacity, which directly improves the integrity of the pattern during vacuum transfer.

[0053] In some embodiments, in step S3, the slurry comprises the following components in parts by mass: 95-105 parts by mass of phosphate-modified epoxy resin, 16-20 parts by mass of silicone rubber microspheres, 26-30 parts by mass of methylhexahydrophthalic anhydride curing agent, and 110-130 parts by mass of middle layer solvent.

[0054] The slurry ratio provides a gas-reactive matrix containing P=O groups through phosphate-modified epoxy resin, which forms a cross-linked network with methylhexahydrophthalic anhydride curing agent at low temperature. At the same time, silicone rubber microspheres are dispersed in it in a specific proportion to form a continuous elastic buffer phase. When the slurry is coated into a film, the phosphate groups can chemically capture gas molecules such as CO2 / H2O and convert them into stable phosphate compounds, while the silicone rubber microspheres absorb the expansion energy of bubbles in a vacuum environment through elastic deformation, inhibiting the growth and rupture of bubbles. The middle layer solvent regulates the viscosity of the system to ensure uniform dispersion of the microspheres. The three work synergistically to form a dense middle layer with both gas elimination and mechanical buffering functions after curing, directly solving the pattern distortion problem caused by bubbles in the transfer process and improving the clarity of the transfer edge.

[0055] In some embodiments, the slurry is prepared by the following method:

[0056] The phosphate-modified epoxy resin and the propylene glycol methyl ether acetate solvent were mixed in a mass ratio of 100:(60-70), and stirred in a planetary mixer at 550-650 rpm for 8-12 minutes to obtain a resin solution;

[0057] Add 26-30 parts by mass of methylhexahydrophthalic anhydride curing agent, 0.7-0.9 parts by mass of leveling agent, and 0.4-0.6 parts by mass of defoaming agent to the resin solution, and stir at 750-850 rpm for 4-6 minutes;

[0058] Add 16 to 20 parts by weight of silicone rubber microspheres in 3 to 5 batches, stirring at 1100 to 1300 rpm for 2.5 to 3.5 minutes after each batch is added, and controlling the temperature to be ≤40°C to obtain a pre-dispersed mixture;

[0059] The pre-dispersed mixture was fed into a horizontal sand mill using zirconium oxide beads (diameter

[0060] 0.28~0.32mm, filling rate 65%~75%);

[0061] The product was circulated for 2 to 4 times under the conditions of a rotor linear speed of 9 m / to 11 m / s and a feed rate of 14 L / to 16 L / min, and the outlet temperature was controlled to be ≤ 50°C to obtain a dispersed slurry;

[0062] Degassing the dispersed slurry at a vacuum degree of -0.09 to -0.1 MPa for 25 to 35 minutes to reduce the gas content to less than 0.5%;

[0063] The solution was filtered through a 100 μm nylon filter and a 20 μm metal sintered mesh in sequence to obtain a defoaming functional slurry.

[0064] In some embodiments, step S4 includes:

[0065] S41, use ultrasonic electrostatic spraying system to spray the suspension, the spray gun voltage is

[0066] +23~+27kV, substrate bias voltage is -4~-6kV, flow rate is 7.2~8.8mL / min, and atomizing gas pressure is 0.11~0.13MPa;

[0067] S42, drying and activation, including infrared hot air drying at a temperature of 55 to 65°C, a drying time of 35 to 45 seconds, a vacuum activation pressure of -0.09 to -0.1 MPa, and an activation time of 20 to 30 seconds.

[0068] In the electrostatic spraying process of step S4, the construction of the gas capture layer is achieved through the synergistic effect of ultrasonic atomization and high-voltage electrostatic field: the spray gun applies a positive voltage of +23 to +27 kV to charge and atomize the graphene aerogel microsphere suspension, and the substrate forms a directional electric field attraction with a negative bias of -4 to -6 kV. Combined with the atomization pressure of 0.11 to 0.13 MPa, the microspheres are evenly dispersed into a single layer of droplets. The flow rate control of 7.2 to 8.8 mL / min ensures the microsphere deposition density per unit area, thereby forming a continuously distributed micropore array on the coating surface; subsequently, 55 to 65 ° C infrared hot air drying is performed for 35 to 45 seconds to selectively remove the surface free water but retain the bound water inside the microspheres, and then -0.09 to -0.1 MPa vacuum activation is performed for 20 to 30 seconds, and the negative pressure difference is used to expand and open the closed-cell structure of the microspheres to form through pores of 0.05 to 0.5 μm. This process combination increases the porosity of the microspheres to more than 93%, and the specific surface area reaches 620 m 2 / g, and efficiently captures the CO2 / H2O gas molecules released during the vacuum transfer process through a physical adsorption mechanism. At the same time, electrostatic parameter optimization avoids coating defects caused by microsphere agglomeration, ultimately reducing the bubble residual rate at the transfer interface to below 2%.

[0069] In some embodiments, in step S4, the suspension comprises 6-8 wt % of graphene aerogel microspheres, 0.2-0.4 wt % of a dispersant, 0.1-0.2 wt % of a wetting agent, and the balance is deionized water.

[0070] In some embodiments, the dispersant is BYK-190 containing a polyurethane block copolymer; and the wetting agent is Dynol 604, an acetylene glycol surfactant.

[0071] In the suspension formulation of step S4, graphene aerogel microspheres (GAMs) are used as gas capture cores at a concentration of 6 to 8 wt%, providing physical adsorption sites through their pore structure of 0.05 to 0.5 μm; BYK-190, a dispersant containing a polyurethane block copolymer, is added at 0.2 to 0.4 wt% to maintain the dispersion stability of the microspheres through a steric effect, preventing nozzle clogging or coating defects due to agglomeration during spraying; Dynol 604, an acetylene glycol wetting agent, is added at 0.1 to 0.2 wt% to reduce the surface tension of the suspension to ≤30 mN / m, thereby improving the wetting and spreading properties of the middle epoxy resin coating and ensuring uniform distribution of the microsphere monolayer. This formula combination enables the microspheres to remain in an isolated and dispersed state during the electrostatic spraying process, forming a continuous and open microporous network per unit area. When the CO2 / H2O gas generated by vacuum transfer diffuses to the upper layer, it is efficiently captured and locked by the high specific surface area structure of the microspheres. At the same time, the wetting agent eliminates the interfacial tension difference and avoids the generation of new bubbles during the drying process, ultimately achieving zero-defect construction of the gas capture layer and completely eliminating the risk of transfer pattern distortion.

[0072] In some embodiments, step S4 further comprises preparing the graphene aerogel microspheres:

[0073] S43, mixing the graphene oxide dispersion and polymethyl methacrylate microspheres in a mass ratio of 1:2.8 to 1:3.2, and subjecting the mixture to alternating ultrasound-centrifugation treatment at an ultrasound frequency of 38 to 42 kHz and a centrifugal speed of 2800 to 3200 rpm for 2 to 4 cycles to obtain a self-assembled mixture;

[0074] S44, placing the self-assembled mixture into a polystyrene microsphere template with a pore size of 0.3-0.5 μm, pre-freezing at -18 to -22°C for 1.5 to 2.5 hours, quick-freezing at -190 to -200°C for 8 to 12 minutes, and then cooling from -5°C to -40°C at a cooling rate of 0.8 to 1.2°C / min to obtain a frozen molded body;

[0075] S45, reducing the frozen molded body in hydroiodic acid (concentration 5 wt%), with a solution pH of 2.5 to 3.5, a temperature of 50° C., and a time of 2 h to obtain a reduction product;

[0076] S46. Dry the reduced product under supercritical CO2 conditions at a pressure of 7.3 to 7.5 MPa, a temperature of 30.5 to 31.5°C, a time of 3.5 to 4.5 h, and a pressure release rate of 0.08 to 0.12 MPa / min to obtain graphene aerogel microspheres.

[0077] In some embodiments, the graphene aerogel microspheres have a pore size of 0.05 to 0.5 μm and a specific surface area of ​​550 m 2 / g, bulk density ≤0.06g / cm 3 , the concentration of the hydroiodic acid is 0.08-0.12 mol / L.

[0078] Graphene aerogel microspheres are designed with a pore size of 0.05 to 0.5 μm to match the bubble size distribution in vacuum transfer, achieving efficient physical capture; the specific surface area is ≥550m 2 / g provides a large number of gas adsorption sites, locking CO2 / H2O molecules through van der Waals force; bulk density ≤ 0.06g / cm 3 Ensure that the microspheres form an open network structure to avoid the thickening of the coating affecting the transfer accuracy; hydroiodic acid concentration of 0.08-0.12 mol / L gently reduces graphene oxide in a pH = 3 environment, which not only retains the integrity of the microsphere skeleton but also restores the conductivity of graphene. This synergistic effect enables the gas capture layer to have anti-static adsorption ability while maintaining porosity, eliminating the edge blur defects of the transfer pattern caused by impurity adhesion.

[0079] In some embodiments, in the plasma treatment of step S1, the plasma gas is a mixture of He and O2, wherein the volume fraction of He is 85% to 95%, the volume fraction of O2 is 5% to 15%, and the power density of the plasma treatment is 0.7 to 0.9 W / cm 2 The processing pressure is atmospheric pressure, the processing speed is 2.5-3.5m / min, and the inter-electrode distance is 1.5-2.5mm.

[0080] The plasma treatment is carried out under atmospheric pressure using a mixture of He and O2, where He is used as the main gas to generate a high-density uniform plasma. The active oxygen free radicals generated by the ionization of O2 react with the carbon-hydrogen chain on the surface of the PO substrate to form polar groups such as hydroxyl and carboxyl groups. At the same time, the plasma is heated to 0.7-0.9W / cm 2 Under the premise of avoiding thermal damage to the substrate, the power density is guaranteed to ensure that the plasma penetration depth covers the substrate surface by 0.1-0.3μm; with the coordinated control of the processing speed of 2.5-3.5m / min and the inter-electrode spacing of 1.5-2.5mm, the plasma residence time and the action distance are optimally balanced, and a uniformly distributed micro-rough structure is constructed on the PO surface, thereby significantly enhancing the chemical bonding strength between the substrate and the underlying coating (Zn 2+Coordination with -COOH) and mechanical intercalation eliminate the interfacial gas adsorption sites from the source, reducing the probability of bubble nucleation in the subsequent coating process.

[0081] In step S6, the hot pressing temperature is 110-120° C., the hot pressing pressure is 0.7-0.9 MPa, the hot pressing time is 40-50 seconds, the hot pressing roller speed is 1.4-1.6 m / min, the curing temperature is 35-45° C., the curing time is 22-26 hours, and the relative humidity of the curing environment is ≤30%.

[0082] By controlling the hot pressing temperature at 110-120°C, slightly higher than the melting point of the CPP / PE layer but lower than the glass transition temperature of PET, the CPP / PE layer melts and flows and tightly wraps the Primer layer. At the same time, the pressure of 0.7-0.9 MPa avoids crushing the middle layer of silicone rubber microspheres, prompting the molten CPP / PE to penetrate into the gaps between the upper graphene aerogel microspheres to form a physical sealing layer. The 40-50s hot pressing time and the 1.4-1.6m / min roller speed are coordinated to ensure that the molecular chains between the layers are fully diffused without causing excessive shrinkage of the PO substrate. The subsequent low-temperature aging of 22-26h and 35-45°C allows the residual stress between the layers to be slowly relaxed and released through the polymer chain segments, while suppressing water vapor intrusion and causing interface debonding. Ultimately, the four-layer structure is permanently composited in a zero-bubble state, ensuring that there is no risk of interface delamination during the transfer process.

[0083] The present application also provides a high-performance PO composite film for OMR vacuum transfer, which is obtained based on any of the aforementioned preparation methods.

[0084] Specifically, the PO composite film includes, in sequence: a PET layer with a thickness of 250 to 260 μm, a PO layer with a thickness of 95 to 105 μm, a Primer layer with a thickness of 21.7 to 25.3 μm, and a CPP / PE layer with a thickness of 25 to 35 μm, wherein the Primer layer is composed of a lower coating layer (2.7 to 3.3 μm), a middle coating layer (11 to 12 μm) and an upper coating layer (8 to 10 μm).

[0085] The PET layer provides rigid support and laser microporous release function, the PO layer maintains the flexibility of the substrate and bears the transfer stress, the Primer layer integrates a three-level defoaming structure, and the CPP / PE layer forms a heat-sealing barrier.

[0086] Among them, the lower coating of 2.7-3.3 μm in the Primer layer ensures the continuous penetration of nano-SiO2 microporous channels (diameter 0.1-0.5 μm), and the middle coating of 11-12 μm accommodates sufficient silicone rubber microspheres. Constructing an elastic buffer network, the upper coating of 8 to 10 μm makes the graphene aerogel microspheres A high-porosity (≥93%) capture layer is formed. This thickness system enables the molten CPP / PE layer to fully fill the gaps between the upper microspheres during hot pressing and compounding, while avoiding the obstruction of heat transfer by an excessively thick PO layer or the tearing of the release film by an excessively thin PET layer. Ultimately, zero gas residue and uniform stress distribution between layers are achieved during the transfer process, ensuring high-precision pattern transfer without distortion.

[0087] The method of the present invention will be described in detail below with reference to embodiments, comparative examples and experimental data.

[0088] Example 1

[0089] This embodiment provides a method for preparing a high-performance PO composite film for OMR vacuum transfer, comprising the following steps:

[0090] S1. Plasma treatment is performed on the PO substrate to obtain a pretreated PO substrate. Specifically, an atmospheric pressure plasma treatment machine is used, using a mixed gas of He and O2, wherein the volume fraction of He is 90%, the volume fraction of O2 is 10%, and the power density of the plasma treatment is 0.8W / cm 2 The treatment pressure is atmospheric pressure, the treatment speed is 3.0m / min, the inter-electrode distance is 2.0mm, and the surface tension of the PO substrate is increased to above 42mN / m after treatment.

[0091] S2. Apply the lower coating layer on the pretreated PO substrate. First, prepare the coating solution: take 100 parts by mass of zinc acrylate, 5 parts by mass of nano-SiO2, 2.5 parts by mass of photoinitiator 184 and 150 parts by mass of the lower layer solvent (isopropyl alcohol), mix them, and after high-speed shear dispersion and ultrasonic homogenization, filter to obtain the coating solution. Then, use a micro-gravure coater to apply the coating solution with a screen count of 180 meshes and a wet film thickness of 10.0 μm; perform infrared drying at a drying temperature of 70°C and a drying time of 20 seconds; perform UV curing with an irradiation intensity of 120 mW / cm 2 , cumulative dose is 600mJ / cm 2 , obtaining a lower coating with a thickness of about 3.0 μm.

[0092] S3. Apply a middle coating layer on the lower coating layer. First, prepare the slurry: take 100 parts by mass of phosphate-modified epoxy resin, 18 parts by mass of silicone rubber microspheres, 28 parts by mass of methyl hexahydrophthalic anhydride curing agent and 120 parts by mass of middle-layer solvent (propylene glycol methyl ether acetate), pre-disperse and sand-mill disperse, and then deaerate and filter. Next, use a precision slit coater to apply the slurry, the substrate speed is 2.0 m / min, and the wet film thickness is 28 μm; perform step curing, including a pre-curing stage at a temperature of 80°C and a time of 3.0 min, a main curing stage at a temperature of 100°C and a time of 2.0 min, and a final curing stage at a temperature of 120°C and a time of 2.0 min, to obtain a middle coating layer with a thickness of about 11.5 μm.

[0093] S4. Spray the upper coating layer on the middle coating layer. First, prepare graphene aerogel microspheres: mix graphene oxide dispersion and polymethyl methacrylate microspheres in a mass ratio of 1:3.0, and undergo alternating ultrasound-centrifugation treatment (ultrasonic frequency 40kHz, centrifugal speed 3000rpm, cycle 3 times) to obtain a self-assembled mixture; pre-freeze the mixture at -20°C for 2.0h, quickly freeze it at -195°C for 10min, and then cool it from -5°C to -40°C at a cooling rate of 1.0°C / min to obtain a frozen molded body; reduce the frozen molded body in a hydroiodic acid solution with a solution pH of 3.0, a temperature of 50°C, and a time of 2h to obtain a reduced product; dry the reduced product under supercritical CO2 conditions at a pressure of 7.4MPa, a temperature of 31°C, a time of 4.0h, and a pressure release rate of 0.1MPa / min to obtain graphene aerogel microspheres. Next, a suspension was prepared: 1.8 wt% graphene aerogel microspheres, 0.3 wt% dispersant (BYK-190), 0.15 wt% wetting agent (Dynol 604), and the balance deionized water. The suspension was then sprayed using an ultrasonic electrostatic spray system with a gun voltage of +25 kV, a substrate bias of -5 kV, a flow rate of 8.0 mL / min, and an atomization pressure of 0.12 MPa. Drying and activation were performed using infrared hot air drying at 60°C for 40 seconds and vacuum activation at -0.095 MPa for 25 seconds, resulting in an upper coating with a thickness of approximately 3.5 μm.

[0094] S5. Post-curing the upper coating layer with a hot air circulation temperature of 130°C for 90 seconds to obtain a cured Primer layer consisting of a lower coating layer, a middle coating layer and an upper coating layer with a total thickness of about 23.5 μm.

[0095] S6. Stack the PET layer (thickness of about 255 μm), the PO layer (thickness of about 100 μm), the cured Primer layer and the CPP / PE layer (thickness of about 30 μm) in sequence and perform hot pressing compounding. The hot pressing temperature is 115°C, the hot pressing pressure is 0.8 MPa, the hot pressing time is 45 s, and the hot pressing roller speed is 1.5 m / min. Then, the aging temperature is 40°C, the aging time is 24 h, and the relative humidity of the aging environment is ≤30%, and finally a high-performance PO composite film for OMR vacuum transfer is obtained.

[0096] Example 2

[0097] This embodiment provides a method for preparing a high-performance PO composite film for OMR vacuum transfer, comprising the following steps:

[0098] S1. Plasma treatment is performed on the PO substrate to obtain a pretreated PO substrate. Specifically, an atmospheric pressure plasma treatment machine is used, using a mixed gas of He and O2, wherein the volume fraction of He is 95%, the volume fraction of O2 is 5%, and the power density of the plasma treatment is 0.9 W / cm 2 The treatment pressure is atmospheric pressure, the treatment speed is 3.5m / min, the inter-electrode distance is 2.5mm, and the surface tension of the PO substrate is increased to above 42mN / m after treatment.

[0099] S2. Apply the lower coating layer on the pretreated PO substrate. First, prepare the coating solution: take 110 parts by mass of zinc acrylate, 6 parts by mass of nano-SiO2, 3.0 parts by mass of photoinitiator 184 and 160 parts by mass of the lower layer solvent (isopropyl alcohol), mix them, and after high-speed shear dispersion and ultrasonic homogenization, filter to obtain the coating solution. Then, use a micro-gravure coater to apply the coating solution with a screen count of 190 meshes and a wet film thickness of 10.5 μm; perform infrared drying at a drying temperature of 75°C and a drying time of 25 seconds; perform UV curing with an irradiation intensity of 130 mW / cm 2 , the cumulative dose is 650mJ / cm 2 , obtaining a lower coating with a thickness of about 3.0 μm.

[0100] S3. Apply a middle layer of coating on the lower layer of coating. First, prepare the slurry: take 105 parts by mass of phosphate-modified epoxy resin, 20 parts by mass of silicone rubber microspheres, 30 parts by mass of methyl hexahydrophthalic anhydride curing agent and 130 parts by mass of middle layer solvent (propylene glycol methyl ether acetate), pre-disperse and sand-mill disperse, and then deaerate and filter. Next, use a precision slit coater to apply the slurry, the substrate speed is 2.2m / min, and the wet film thickness is 29μm; perform step curing, including a pre-curing stage at a temperature of 85°C and a time of 3.5min, a main curing stage at a temperature of 105°C and a time of 2.5min, and a final curing stage at a temperature of 125°C and a time of 2.5min, to obtain a middle layer coating with a thickness of about 11.5μm.

[0101] S4. Spray the upper coating layer on the middle coating layer. First, prepare graphene aerogel microspheres: mix graphene oxide dispersion and polymethyl methacrylate microspheres in a mass ratio of 1:3.2, and undergo alternating ultrasound-centrifugation treatment (ultrasonic frequency 42kHz, centrifugal speed 3200rpm, cycle 4 times) to obtain a self-assembled mixture; pre-freeze the mixture at -18°C for 1.5h, quickly freeze it at -190°C for 8min, and then cool it from -5°C to -40°C at a cooling rate of 1.2°C / min to obtain a frozen molded body; reduce the frozen molded body in a hydroiodic acid solution with a pH of 2.5, a temperature of 50°C, and a time of 2h to obtain a reduced product; dry the reduced product under supercritical CO2 conditions at a pressure of 7.5MPa, a temperature of 31.5°C, a time of 4.5h, and a pressure release rate of 0.12MPa / min to obtain graphene aerogel microspheres. Next, a suspension was prepared: 2.1 wt% graphene aerogel microspheres, 0.4 wt% dispersant (BYK-190), 0.2 wt% wetting agent (Dynol 604), and the balance deionized water. The suspension was then sprayed using an ultrasonic electrostatic spray system with a gun voltage of +27 kV, a substrate bias of -6 kV, a flow rate of 8.8 mL / min, and an atomization pressure of 0.13 MPa. Drying and activation were performed using infrared hot air drying at 65°C for 45 seconds and vacuum activation at -0.1 MPa for 30 seconds, resulting in an upper coating with a thickness of approximately 3.5 μm.

[0102] S5. Post-curing the upper coating layer with a hot air circulation temperature of 135°C for 100 seconds to obtain a cured Primer layer consisting of a lower coating layer, a middle coating layer and an upper coating layer with a total thickness of about 23.5 μm.

[0103] S6. Stack the PET layer (thickness of about 255 μm), the PO layer (thickness of about 100 μm), the cured Primer layer and the CPP / PE layer (thickness of about 30 μm) in sequence and perform hot pressing compounding. The hot pressing temperature is 120°C, the hot pressing pressure is 0.9 MPa, the hot pressing time is 50 s, and the hot pressing roller speed is 1.6 m / min. Then, the aging temperature is 45°C, the aging time is 26 h, and the relative humidity of the aging environment is ≤30%, and finally a high-performance PO composite film for OMR vacuum transfer is obtained.

[0104] Example 3

[0105] This embodiment provides a method for preparing a high-performance PO composite film for OMR vacuum transfer, comprising the following steps:

[0106] S1. Plasma treatment is performed on the PO substrate to obtain a pretreated PO substrate. Specifically, an atmospheric pressure plasma treatment machine is used, using a mixed gas of He and O2, wherein the volume fraction of He is 85%, the volume fraction of O2 is 15%, and the power density of the plasma treatment is 0.7 W / cm 2 The treatment pressure is atmospheric pressure, the treatment speed is 2.5m / min, the inter-electrode distance is 1.5mm, and the surface tension of the PO substrate is increased to above 42mN / m after treatment.

[0107] S2. Apply the lower coating layer on the pretreated PO substrate. First, prepare the coating solution: take 90 parts by mass of zinc acrylate, 4 parts by mass of nano-SiO2, 2.0 parts by mass of photoinitiator 184 and 140 parts by mass of the lower layer solvent (isopropyl alcohol), mix them, and after high-speed shear dispersion and ultrasonic homogenization, filter to obtain the coating solution. Then, use a micro-gravure coater to apply the coating solution with a screen count of 170 meshes and a wet film thickness of 9.5 μm; perform infrared drying at a drying temperature of 65°C and a drying time of 15 seconds; perform UV curing with an irradiation intensity of 110 mW / cm 2 , the cumulative dose is 550mJ / cm 2 , obtaining a lower coating with a thickness of about 3.0 μm.

[0108] S3. Apply a middle layer of coating on the lower layer of coating. First, prepare the slurry: take 95 parts by mass of phosphate-modified epoxy resin, 16 parts by mass of silicone rubber microspheres, 26 parts by mass of methyl hexahydrophthalic anhydride curing agent and 110 parts by mass of middle layer solvent (propylene glycol methyl ether acetate), pre-disperse and sand-mill disperse, then deaerate and filter. Next, use a precision slit coater to apply the slurry, the substrate speed is 1.8m / min, and the wet film thickness is 27μm; perform step curing, including a pre-curing stage at a temperature of 75°C and a time of 2.5min, a main curing stage at a temperature of 95°C and a time of 1.5min, and a final curing stage at a temperature of 115°C and a time of 1.5min, to obtain a middle layer coating with a thickness of about 11.5μm.

[0109] S4. Spray the upper coating layer on the middle coating layer. First, prepare graphene aerogel microspheres: mix graphene oxide dispersion and polymethyl methacrylate microspheres in a mass ratio of 1:2.8, and perform alternating ultrasound-centrifugation treatment (ultrasonic frequency 38kHz, centrifugal speed 2800rpm, cycle 2 times) to obtain a self-assembled mixture; pre-freeze the mixture at -22°C for 2.5h, then quickly freeze it at -200°C for 12min, and then cool it from -5°C to -40°C at a cooling rate of 0.8°C / min to obtain a frozen molded body; reduce the frozen molded body in a hydroiodic acid solution with a pH of 3.5, a temperature of 50°C, and a time of 2h to obtain a reduced product; dry the reduced product under supercritical CO2 conditions at a pressure of 7.3MPa, a temperature of 30.5°C, a time of 3.5h, and a pressure release rate of 0.08MPa / min to obtain graphene aerogel microspheres. Next, a suspension was prepared: 1.5 wt% graphene aerogel microspheres, 0.2 wt% dispersant (BYK-190), 0.1 wt% wetting agent (Dynol 604), and the balance deionized water. The suspension was then sprayed using an ultrasonic electrostatic spray system with a gun voltage of +23 kV, a substrate bias of -4 kV, a flow rate of 7.2 mL / min, and an atomization pressure of 0.11 MPa. Drying and activation were performed using infrared hot air drying at 55°C for 35 seconds and vacuum activation at -0.09 MPa for 20 seconds, resulting in an upper coating with a thickness of approximately 3.5 μm.

[0110] S5. Post-curing the upper coating layer with a hot air circulation temperature of 125°C for 80 seconds to obtain a cured Primer layer consisting of a lower coating layer, a middle coating layer and an upper coating layer with a total thickness of about 23.5 μm.

[0111] S6. The PET layer (thickness of about 255 μm), the PO layer (thickness of about 100 μm), the cured Primer layer and the CPP / PE layer (thickness of about 30 μm) are stacked in sequence and hot-pressed for compounding. The hot-pressing temperature is 110°C, the hot-pressing pressure is 0.7 MPa, the hot-pressing time is 40 s, and the hot-pressing roller speed is 1.4 m / min. Then, the film is cured at a temperature of 35°C, a time of 22 h, and a relative humidity of the curing environment is ≤30%. Finally, a high-performance PO composite film for OMR vacuum transfer is obtained.

[0112] Comparative Example 1

[0113] This comparative example provides a method for preparing a high-performance PO composite film for OMR vacuum transfer, which differs from Example 1 in that:

[0114] In step S1 , the PO substrate is not subjected to plasma treatment.

[0115] Comparative Example 2

[0116] This comparative example provides a method for preparing a high-performance PO composite film for OMR vacuum transfer, which differs from Example 1 in that:

[0117] No nano-SiO2 is added to the coating solution in step S2.

[0118] Comparative Example 3

[0119] This comparative example provides a method for preparing a high-performance PO composite film for OMR vacuum transfer, which differs from Example 1 in that:

[0120] No silicone rubber microspheres are added to the slurry in step S3.

[0121] Comparative Example 4

[0122] This comparative example provides a method for preparing a high-performance PO composite film for OMR vacuum transfer, which differs from Example 1 in that:

[0123] No graphene aerogel microspheres are added to the suspension in step S4.

[0124] Comparative Example 5

[0125] This comparative example provides a method for preparing a high-performance PO composite film for OMR vacuum transfer, which differs from Example 1 in that:

[0126] The post-curing hot air circulation temperature in step S5 is 140°C.

[0127] The properties of the high-strength and high-density quartz fiber reinforced quartz composite materials prepared by the methods provided in the above embodiments and comparative examples were tested. The testing method is as follows:

[0128] 1. Bubble defect rate

[0129] Test method: Take a 10cm×10cm composite film sample, place it on an LED backlight test bench (1000 lux), and use a 200x digital microscope (Dino-Lite AM7915MZT) to observe the coating surface. Count the number of bubbles with a diameter of ≥5μm and calculate the defect rate per unit area: bubble defect rate (number / cm 2 ) = total number of bubbles / detection area (100cm 2 ).

[0130] 2. Clarity of the edge of the transfer pattern

[0131] Testing method: A standard test pattern (100μm grid width) was vacuum-transferred onto the composite film at a transfer pressure of -0.08MPa, a temperature of 120°C, and a transfer time of 30 seconds. The jagged offset of the transferred lines was measured using an optical microscope (Olympus BX43). The average value of 10 lines was taken: Edge offset (μm) = |Designed line width - Actual line width|.

[0132] 3. Interlayer peeling strength

[0133] Test method: In accordance with GB / T 2792-2014, the non-composite surface of the PET layer and the non-composite surface of the CPP / PE layer of a composite film sample (150 mm × 25 mm) were bonded to two rigid metal fixtures using fast-curing epoxy adhesive (0.1 mm thickness or less). After curing at room temperature for 20 minutes, the film was loaded into a stretching apparatus. The upper fixture held the PET side metal plate, and the lower fixture held the CPP / PE side metal plate. A 90° vertical peel was performed at a speed of 100 mm / min. The initial 25 mm was the pre-peel section, and the data from the subsequent 100 mm effective section were used to calculate the peel strength (N / 25 mm). A 90° peel test was performed at a tensile speed of 100 mm / min, and the peak peel force was recorded: Peel strength (N / 25 mm) = average peel force / sample width.

[0134] Table 1 Performance test results

[0135] Group <![CDATA[Bubble defect rate (number / cm 2 )]]> Edge offset (μm) Peel strength (N / 25mm) Example 1 0.8 3.2 4.5 Example 2 1.1 3.6 4.3 Example 3 1.3 4.0 4.1 Comparative Example 1 5.6 8.5 1.8 Comparative Example 2 4.2 6.8 3.9 Comparative Example 3 3.5 12.3 4.0 Comparative Example 4 3.0 7.2 4.1 Comparative Example 5 2.5 5.0 3.0

[0136] Experimental results analysis

[0137] In Example 1, the plasma He / O2=90% / 10%, the coating mesh 180 mesh, and the step curing 80-120℃ were used, and the bubble defect rate was measured to be only 0.8 / cm 2 , indicating that the gas escape channel is complete and the three-stage defoaming process is fully synergistic. A transfer edge offset of 3.2μm verifies the coating's effective suppression of bubble expansion, ensuring pattern accuracy. A peel strength of 4.5N / 25mm demonstrates a strong interfacial bond formed by plasma treatment and hot pressing (115°C / 0.8MPa). This parameter combination achieves an optimal balance between eliminating bubbles, maintaining transfer quality, and enhancing interlayer bonding.

[0138] In Example 2, when He 95%, mesh 190, and curing temperature 125°C were used, the bubble defect rate slightly increased to 1.1 / cm 2This may be due to the shortened plasma exposure time at high-speed processing (3.5 m / min) or the partial closure of micropores caused by high-temperature curing. The edge offset of 3.6 μm maintains a high degree of precision, indicating that the electrostatic spraying parameters (+27 kV / -6 kV) can still ensure uniform distribution of graphene microspheres. The slight decrease in peel strength of 4.3 N / 25 mm may be due to accelerated aging of the PO layer during hot pressing at 120°C, but the extended aging time to 26 hours compensates for the release of interlayer stress. This shows that even at extreme parameters, performance is still superior to the comparative example.

[0139] In Example 3, the bubble defect rate increased to 1.3 / cm at He 85%, mesh 170, and curing temperature 115°C. 2 The low processing speed (2.5 m / min) resulted in incomplete evaporation of the lower layer solvent, leaving trace amounts of gas. The edge offset of 4.0 μm indicates that the reduced coating thickness (9.5 μm) slightly impaired gas escape efficiency. However, the peel strength of 4.1 N / 25 mm demonstrates that low-temperature hot pressing (110°C) effectively controlled the CPP / PE melt flowability, preventing collapse of the mid-layer microsphere structure. This demonstrates that even a conservative process can maintain functional integrity, highlighting the robustness of the method.

[0140] Comparative Example 1 adopted measures without plasma treatment, and the bubble defect rate increased sharply to 5.6 / cm 2 , indicating that no polar groups and micro-rough structures were formed on the surface of the PO substrate, resulting in insufficient adhesion of the underlying coating and ineffective escape of interfacial gas; the edge offset of 8.5μm indicated that the expansion of interfacial bubbles was not suppressed during transfer; when the peel strength was tested after hot pressing and lamination, the PO substrate was not firmly bonded to the Primer layer because it had not been plasma treated. As a result, when the PET layer was peeled off, the PO substrate PET layer was lifted up, and interlayer peeling occurred between the PO substrate and the Primer layer, resulting in a significant decrease in peel strength, confirming the lack of chemical bonding between the substrate and the coating.

[0141] The lower layer of Comparative Example 2 lacks nano-SiO2, resulting in a bubble defect rate of 4.2 / cm 2 This is significantly higher than Example 1 (0.8), due to the lack of 0.1-0.5 μm microporous channels, which prevent gas from escaping during the infrared drying stage. The edge offset of 6.8 μm reflects that bubbles are not eliminated promptly after nucleation, interfering with transfer accuracy. However, the peel strength of 3.9 N / 25 mm is close to that of the example, indicating that this defect primarily affects the defoaming function rather than the interface bonding.

[0142] Comparative Example 3 lacks silicone rubber microspheres in the middle layer, resulting in an edge offset of up to 12.3 μm, far exceeding that of other comparative examples. This proves that after the middle layer loses its elastic buffering ability, the energy of bubble expansion in a vacuum environment directly destroys the integrity of the pattern; the bubble defect rate is 3.5 / cm 2This indicates that chemical capture (phosphate groups), while partially effective, cannot compensate for the lack of mechanical energy buffering. The peel strength of 4.0 N / 25 mm suggests that this modification has limited impact on interlayer bonding.

[0143] The upper layer of comparative example 4 lacks graphene aerogel microspheres, resulting in a bubble defect rate of 3.0 / cm 2 The deterioration is synchronized with the edge offset of 7.2μm, indicating that the loss of the physical adsorption layer makes it impossible to capture the residual gas, especially the loss of the pore opening mechanism during the vacuum activation stage; the peel strength of 4.1N / 25mm is not affected, confirming that this layer mainly undertakes the terminal gas capture function.

[0144] Comparative Example 5 was cured at 140°C, resulting in a sharp drop in peel strength to 3.0N / 25mm. This was due to excessive cross-linking, which made the Primer layer brittle. During hot pressing, the CPP / PE melt layer could not effectively penetrate the gaps between the microspheres. The bubble defect rate was 2.5 / cm. 2 The slight increase of 5.0 μm in the edge offset indicates that high temperature may damage the structure of the silicone rubber microspheres in the middle layer and weaken the elastic cushioning capacity.

[0145] In summary, Examples 1-3 achieved a bubble defect rate of ≤1.3 / cm by combining plasma treatment with a three-level coating (a lower layer containing microporous channels, an elastic buffer middle layer, and a high adsorption upper layer) and a precise temperature control process. 2 , transfer edge offset ≤ 4.0μm, peel strength ≥ 4.1N / 25mm; while the control samples had systematic performance degradation due to single link missing (such as no plasma treatment, lack of nano-SiO2 micropores, lack of silicone rubber microspheres or graphene microspheres) or parameter out of range (post-curing at 140℃): bubble defect rate surged by 275%-600% (up to 5.6 / cm 2 ), the edge offset is expanded to 5.0-12.3 μm (Comparative Example 3 is 3 times that of Example 1), and the peel strength drops sharply by 33%-60% (Comparative Example 1 is only 1.8 N / 25 mm), proving that each component and parameter in the complete process chain is irreplaceable, and the balanced parameters of Example 1 are the optimal solution.

[0146] The applicant declares that the present invention uses the above-described embodiments to illustrate the detailed process flow of the present invention, but the present invention is not limited to the above-described detailed process flow, that is, it does not mean that the present invention must rely on the above-described detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for various raw materials in the products of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a high-performance PO composite film for OMR vacuum transfer, characterized in that: The following steps are involved: S1. Plasma-treating a PO substrate to obtain a pretreated PO substrate; S2, coating a lower coating on the pretreated PO substrate, wherein the lower coating is formed by a coating solution comprising zinc acrylate, nano-SiO2, a photoinitiator 184, and a lower solvent, and after coating, infrared drying and UV curing are performed to obtain a lower coating; S3, coating a middle coating on the lower coating, wherein the middle coating is formed from a slurry comprising a phosphate-modified epoxy resin, silicone rubber microspheres, a methyl hexahydrophthalic anhydride curing agent, and a middle-layer solvent, and step-curing the coating to obtain a middle coating; S4, spraying an upper coating layer on the middle coating layer, wherein the upper coating layer is formed by a suspension containing graphene aerogel microspheres, and drying and vacuum activating the upper coating layer after spraying to obtain the upper coating layer; S5, post-curing the upper coating layer with hot air circulation at a temperature of 125-135° C. for 80-100 seconds to obtain a cured Primer layer consisting of a lower coating layer, a middle coating layer, and an upper coating layer; S6. Stacking the PET layer, the PO layer, the cured Primer layer and the CPP / PE layer in sequence, performing hot pressing and lamination, and then aging to obtain the PO composite film.

2. The preparation method according to claim 1, characterized in that Step S2 includes: S21, apply the coating liquid using a micro-gravure coater, with a screen count of 170-190 meshes and a wet film thickness of 9.5-10.5 μm; S22, infrared drying, drying temperature is 65-75℃, drying time is 15-25s; S23, UV curing, irradiation intensity is 110~130mW / cm 2 , cumulative dose is 550~650mJ / cm 2 .

3. The preparation method according to claim 2, characterized in that In step S2, the coating solution comprises the following components in parts by mass: 90 to 110 parts by mass of zinc acrylate, 4 to 6 parts by mass of nano-SiO2, 2.0 to 3.0 parts by mass of photoinitiator, and 140 to 160 parts by mass of lower layer solvent.

4. The preparation method according to claim 1, characterized in that Step S3 includes: S31, using a precision slit coater to apply the slurry, with a substrate speed of 1.8 to 2.2 m / min and a wet film thickness of 27 to 29 μm; S32, step curing, including a pre-curing stage at a temperature of 75-85°C and a time of 2.5-3.5 minutes, a main curing stage at a temperature of 95-105°C and a time of 1.5-2.5 minutes, and a final curing stage at a temperature of 115-125°C and a time of 1.5-2.5 minutes.

5. The preparation method according to claim 4, characterized in that In step S3, the slurry contains the following components in parts by mass: 95-105 parts by mass of phosphate-modified epoxy resin, 16-20 parts by mass of silicone rubber microspheres, 26-30 parts by mass of methylhexahydrophthalic anhydride curing agent, and 110-130 parts by mass of middle layer solvent.

6. The preparation method according to claim 1, characterized in that Step S4 includes: S41, spraying the suspension using an ultrasonic electrostatic spraying system, with a spray gun voltage of +23 to +27 kV, a substrate bias of -4 to -6 kV, a flow rate of 7.2 to 8.8 mL / min, and an atomizing pressure of 0.11 to 0.13 MPa; S42, drying and activation, including infrared hot air drying at a temperature of 55 to 65°C, a drying time of 35 to 45 seconds, a vacuum activation pressure of -0.09 to -0.1 MPa, and an activation time of 20 to 30 seconds.

7. The preparation method according to claim 6, characterized in that In step S4, the suspension contains 1.5-2.1 wt% of graphene aerogel microspheres, 0.2-0.4 wt% of a dispersant, 0.1-0.2 wt% of a wetting agent, and the balance is deionized water.

8. The preparation method according to claim 7, characterized in that Step S4 also includes preparing the graphene aerogel microspheres: S43, mixing the graphene oxide dispersion and polymethyl methacrylate microspheres in a mass ratio of 1:2.8 to 1:3.2, and subjecting the mixture to alternating ultrasound-centrifugation treatment at an ultrasound frequency of 38 to 42 kHz and a centrifugal speed of 2800 to 3200 rpm for 2 to 4 cycles to obtain a self-assembled mixture; S44, pre-freezing the self-assembly mixture at -18 to -22°C for 1.5 to 2.5 hours, quick-freezing at -190 to -200°C for 8 to 12 minutes, and then cooling from -5°C to -40°C at a cooling rate of 0.8 to 1.2°C / min to obtain a frozen molded body; S45, reducing the frozen molded body in hydroiodic acid at a solution pH of 2.5 to 3.5, a temperature of 50° C., and a time of 2 h to obtain a reduced product; S46. Dry the reduced product under supercritical CO2 conditions at a pressure of 7.3 to 7.5 MPa, a temperature of 30.5 to 31.5°C, a time of 3.5 to 4.5 h, and a pressure release rate of 0.08 to 0.12 MPa / min to obtain graphene aerogel microspheres.

9. The preparation method according to claim 1, characterized in that In the plasma treatment of step S1, the plasma gas is a mixed gas of He and O2, wherein the volume fraction of He is 85% to 95%, the volume fraction of O2 is 5% to 15%, and the power density of the plasma treatment is 0.7 to 0.9 W / cm 2 , the processing pressure is atmospheric pressure, the processing speed is 2.5-3.5m / min, and the inter-electrode distance is 1.5-2.5mm; In step S6, the hot pressing temperature is 110-120° C., the hot pressing pressure is 0.7-0.9 MPa, the hot pressing time is 40-50 seconds, the hot pressing roller speed is 1.4-1.6 m / min, the curing temperature is 35-45° C., the curing time is 22-26 hours, and the relative humidity of the curing environment is ≤30%.

10. A high-performance PO composite film for OMR vacuum transfer, characterized in that: Based on any one of the preparation methods of rights 1-9.