High-performance po composite film for omr vacuum transfer and preparation method thereof

Abstract

The application discloses a kind of high-performance PO composite film for OMR vacuum transfer printing and preparation method thereof, belong to heat transfer printing technical field, preparation method includes: PO base material is treated by plasma, then lower layer, middle layer and upper layer coating are coated in turn, solidification is carried out after each coating, and solidification Primer layer is formed, lower layer coating is formed by coating fluid containing zinc acrylate, nano-SiO2, photoinitiator and lower layer solvent, middle layer coating is formed by slurry of epoxy resin, silicone rubber microsphere, curing agent and middle layer solvent, upper layer coating is formed by suspension containing graphene aerogel microsphere;PET layer, PO layer, solidification Primer layer and CPP / PE layer are stacked in order, and maturation is obtained after hot-pressing compounding, to obtain PO composite film.The method builds gas escape channel, chemical capture and physical adsorption barrier by three-level coating, significantly eliminates vacuum transfer printing bubble, and improves pattern accuracy and interlayer bonding strength.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of heat transfer printing, and particularly relates to a high-performance PO composite film for OMR vacuum transfer printing and a preparation method thereof. BACKGROUND

[0002] In the field of optical mark recognition (OMR), vacuum transfer printing process is widely used in the manufacturing of labels, signs and other products. The core of the process is to realize the accurate transfer of patterns through functional polymer films. In the prior art, the composite film usually adopts 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 process to provide mechanical support and transfer function. However, such composite films are easily affected by material interface characteristics and process parameters in a vacuum environment, resulting in unstable transfer efficiency and limiting their promotion in high-speed and high-precision application scenarios.

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

[0004] Therefore, the key technical problem to be solved for the existing OMR vacuum transfer printing composite film is: how to design a high-performance film structure to effectively suppress the formation of bubbles in a vacuum environment, ensure the uniformity and reliability of the transfer printing process, and maintain the mechanical strength and production efficiency of the film. The solution to this problem will significantly improve the transfer printing quality and meet the increasingly stringent industrial application requirements. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a preparation method of a high-performance PO composite film for OMR vacuum transfer, comprising the following steps: S1, plasma treatment of a PO substrate to obtain a pretreated PO substrate; S2, coating a lower coating layer on the pretreated PO substrate, the lower coating layer being formed by a coating liquid containing zinc acrylate, nano-SiO2, a photoinitiator 184 and a lower solvent, and after coating, the lower coating layer is obtained through infrared drying and UV curing; S3, coating a middle coating layer on the lower coating layer, the middle coating layer being formed by a slurry containing a phosphate-modified epoxy resin, silicone rubber microspheres, a methylhexahydrophthalic anhydride curing agent and a middle layer solvent, and after coating, the middle coating layer is obtained through step curing; S4, spraying an upper coating layer on the middle coating layer, the upper coating layer being formed by a suspension containing graphene aerogel microspheres, and after spraying, the upper coating layer is obtained through drying and vacuum activation; S5, post-curing the upper coating layer, the hot air circulation temperature being 125-135 DEG C, and the time being 80-100 s, to obtain a cured primer layer composed of the lower coating layer, the middle coating layer and the upper coating layer; and S6, sequentially stacking a PET layer, a PO layer, the cured primer layer and a CPP / PE layer, performing hot pressing compounding, and then aging to obtain the PO composite film.

[0006] In some embodiments, step S2 comprises: S21, coating the coating liquid using a micro-gravure coater, the mesh number being 170-190, and the wet film thickness being 9.5-10.5 mu m; S22, infrared drying, the drying temperature being 65-75 DEG C, and the drying time being 15-25 s; and S23, UV curing, the irradiation intensity being 110-130 mW / cm 2 , and the cumulative dose being 550-650 mJ / cm 2 .

[0007] In some embodiments, in step S2, the coating liquid contains the following components in mass fraction: zinc acrylate 90-110 mass parts, nano-SiO2 4-6 mass parts, a photoinitiator 2.0-3.0 mass parts, and a lower solvent 140-160 mass parts.

[0008] In some embodiments, step S3 comprises: S31, coating the slurry using a precision slot coater, the substrate walking speed being 1.8-2.2 m / min, and the wet film thickness being 27-29 mu m; and S32, step curing, including a pre-curing stage temperature of 75-85 DEG C for 2.5-3.5 min, a main curing stage temperature of 95-105 DEG C for 1.5-2.5 min, and a final curing stage temperature of 115-125 DEG C for 1.5-2.5 min.

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

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

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

[0012] In some embodiments, step S4 further comprises preparing the graphene aerogel microspheres: S43, mixing a graphene oxide dispersion solution with polymethyl methacrylate microspheres at a mass ratio of 1:2.8 to 1:3.2, and alternately treating by ultrasonic and centrifugation, the ultrasonic frequency being 38 to 42 kHz, the centrifugal speed being 2800 to 3200 rpm, and the cycle being 2 to 4 times, to obtain a self-assembled mixture; S44, pre-freezing the self-assembled mixture at -18 to -22℃ for 1.5 to 2.5 h, then rapidly freezing at -190 to -200℃ for 8 to 12 min, and then cooling from -5℃ to -40℃ at a rate of 0.8 to 1.2℃ / min, to obtain a freeze-formed body; S45, reducing the freeze-formed body in hydriodic acid, the solution pH being 2.5 to 3.5, the temperature being 50℃, and the time being 2 h, to obtain a reduction product; and S46, drying the reduction product under supercritical CO2 conditions, the pressure being 7.3 to 7.5 MPa, the temperature being 30.5 to 31.5℃, the time being 3.5 to 4.5 h, and the depressurization rate being 0.08 to 0.12 MPa / 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% and 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 distance is 1.5-2.5 mm; in the step S6, the hot-pressing temperature is 110-120 DEG 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 curing temperature is 35-45 DEG C, the curing time is 22-26 h, and the curing environment relative humidity is less than or equal to 30%.

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

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

[0016] 1. By plasma treatment combined with zinc acrylate-nano SiO2 composite coating, the surface energy of the PO substrate is increased to more than 42 mN / m, and a 0.1-0.5 mu m through micro-pore channel is formed, thereby reducing the interface bubble nucleation probability from the source and reducing the coating defect rate.

[0017] 2. By the synergy of phosphoric acid ester modified epoxy resin chemical capture, silicone rubber microsphere elastic buffer and graphene aerogel physical adsorption, a dynamic defoaming barrier is formed in the middle layer and the upper layer, and the vacuum transfer printing pattern edge offset is extremely low.

[0018] 3. By temperature-time synergistic control of step curing and post-curing, the epoxy resin is completely crosslinked and the microsphere structure is avoided from being damaged, and at the same time, the CPP / PE melting layer tightly covers the Primer structure during hot-pressing compounding, thereby enhancing the interlayer peeling strength.

[0019] 4. By optimizing the electrostatic spraying parameters and controlling the vacuum activation pressure, the graphene aerogel microspheres are uniformly distributed and have high porosity, the gas adsorption efficiency is improved, and the zero bubble residue in the transfer printing process is ensured.

[0020] 5. By sanding dispersion and vacuum degassing process, the silicone rubber microspheres are uniformly dispersed and have extremely low gas content, the coating stripe defects are eliminated, and the coating surface consistency is ensured. DETAILED DESCRIPTION

[0021] To make the purpose, technical solutions and advantages of the embodiments of the application clearer, the technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the application.

[0022] The application provides a preparation method of a high-performance PO composite film for OMR vacuum transfer, comprising the following steps:

[0023] S1, plasma treatment is performed on a PO base material to obtain a pretreated PO base material;

[0024] S2, a lower coating is coated on the pretreated PO base material, the lower coating is formed by a coating liquid containing zinc acrylate, nano-SiO2, a photoinitiator 184 and a lower solvent, and after coating, infrared drying and UV curing are performed to obtain the lower coating;

[0025] S3, a middle coating is coated on the lower coating, the middle coating is formed by a slurry containing a phosphate-modified epoxy resin, a silicone rubber microsphere, a methylhexahydrophthalic anhydride curing agent and a middle solvent, and after coating, step-by-step curing is performed to obtain the middle coating;

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

[0027] S5, post-curing is performed on the upper coating, the hot air circulation temperature is 125-135 DEG C, and the time is 80-100 s, to obtain a cured primer layer composed of the lower coating, the middle coating and the upper coating;

[0028] S6, a PET layer, a PO layer, the cured primer layer and a CPP / PE layer are sequentially stacked, hot pressing is performed, and then aging is performed, to obtain the PO composite film.

[0029] The application solves the problem of vacuum transfer bubbles through the synergistic effect of three coatings.

[0030] In S1-S2, a gas escape channel is established: the plasma treatment introduces polar groups on the surface of the PO base material to improve the interfacial bonding force; zinc acrylate is cured to form an ionic crosslinking network, and the nano-SiO2 modified by KH-570 constructs a microporous channel with a pore size of 0.1-0.5 microns in the coating, so that the interfacial gas preferentially escapes in the infrared drying stage, thereby reducing the nucleation sites of bubbles from the source.

[0031] In S3-S4, dynamic bubble elimination is achieved: the P=O groups of the phosphate-modified epoxy resin in the middle coating chemically capture CO2 / H2O and other gas molecules to form stable phosphate compounds; the silicone rubber microspheres absorb the energy of bubble expansion through elastic deformation to inhibit the growth of bubbles; the upper graphene aerogel microspheres open the closed pore structure through vacuum activation, physically adsorb the residual gas through the super large specific surface area, and form a three-level bubble capture barrier.

[0032] In S5-S6 of the present application, the structure is sealed: the post-curing promotes the complete crosslinking of the middle layer of epoxy resin, and seals the potential gas release source; the melted CPP / PE layer serves as a sealing layer to wrap the Primer structure during the hot-pressing compounding, and the aging process makes the interlayer molecular chains slowly relax, eliminates the interface stress microcavity, and finally realizes the bubble-free compounding through the synergistic effect of temperature-pressure-time.

[0033] The present application improves the surface energy of the PO substrate and forms a gas escape path by plasma treatment combined with zinc acrylate-nano SiO2 composite coating, thereby significantly reducing the interface bubble nucleation probability from the source and the defect rate of coating. The P=O group of the phosphate-modified epoxy resin chemically captures the gas, the silicone rubber microspheres elastically buffer the expansion energy, and the physical adsorption of the graphene aerogel microspheres is synergistic, so that the middle layer and the upper layer form a three-level dynamic defoaming barrier, eliminating the bubble residue in a vacuum environment and ensuring the improvement of the edge definition of the transferred pattern. Through the synergistic effect of step curing and post-curing, the middle layer of epoxy resin is completely cured without damaging the microsphere structure, and at the same time, the CPP / PE melting layer tightly covers the Primer structure during hot-pressing compounding, and the aging process releases the interlayer stress, realizing zero bubble residue at the interface of the composite film and improving the yield of the product. Through the optimization of the electrostatic spraying path and the control of the vacuum activation pressure drop rate, the graphene aerogel microspheres are uniformly distributed and have high porosity, maintaining high specific surface area gas capture capacity, while avoiding coating failure caused by microsphere rupture. Through the sanding dispersion process and vacuum degassing, the silicone rubber microspheres in the middle layer slurry are uniformly dispersed, eliminating the bubbles in the slurry itself and ensuring no stripe defects in the coating process.

[0034] In some embodiments, step S2 comprises:

[0035] S21, coating the coating liquid using a microgravure coater, the screen line number is 170-190 meshes, and the wet film thickness is 9.5-10.5 μm;

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

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

[0038] A uniform wet film layer of 9.5-10.5 pm is formed by a micro gravure coater, with the transfer amount of the coating solution precisely controlled at 170-190 mesh line numbers. The synergistic 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 s to volatilize the isopropyl alcohol solvent, avoiding the generation of new bubbles due to local boiling, while preserving the integrity of the 0.1-0.5 pm microporous structure. Finally, UV curing is performed at 110-130 mW / cm 2 irradiation intensity, 550-650 mJ / cm 2 The cumulative dose precisely triggers the cleavage of photoinitiator 184, promoting the rapid crosslinking of zinc acrylate to form an ionic bond network, achieving a balance between the curing rate and interlayer permeability. This not only fixes the microporous channels of nano-SiO2, but also avoids the closure of the channels due to excessive crosslinking, thereby establishing a stable and efficient gas diffusion path at the source, significantly reducing the risk of bubble residue at the coating interface.

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

[0040] Zinc acrylate 90-110 mass parts is used to construct the main film-forming network, with its zinc ions (Zn 2+ ) forming strong coordination bonds with the plasma-treated PO substrate, while 4-6 mass parts of nano-SiO2 modified by KH-570 are uniformly dispersed in the coating to form 0.1-0.5 pm microporous channels. The 2.0-3.0 mass parts of photoinitiator 184 efficiently cleaves in the 254-365 nm wavelength range, triggering the rapid crosslinking of zinc acrylate to fix the microporous structure. The 140-160 mass parts of isopropyl alcohol solvent (boiling point 82.6 °C) precisely controls the solid content at 40.2 ± 0.5%, and volatilizes during the infrared drying stage, avoiding both solvent residue leading to bubbles and micropore collapse. Finally, a lower layer coating is formed that has both high adhesion and through gas channels, eliminating gas retention at the interface from the source and ensuring defect-free compounding of subsequent coatings.

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

[0042] Mix 90-110 mass parts of zinc acrylate with 140-160 mass parts of isopropyl alcohol, and stir at a speed of 800-1200 rpm for 10-20 min to obtain a zinc acrylate solution;

[0043] adding 4-6 parts by mass of nano-SiO2 to the zinc acrylate solution, dispersing for 3-5 min at a rotation speed of 1000-1400 rpm after each addition, and controlling the temperature to be lower than 40℃ to obtain a preliminary mixture;

[0044] adding 2.0-3.0 parts by mass of a photoinitiator 184 and 0.6-1.0 parts by mass of a leveling agent BYK-333 to the preliminary mixture, and mixing for 4-6 min at a rotation speed of 700-900 rpm to obtain a dispersion slurry;

[0045] ultrasonically treating the dispersion slurry at an ultrasonic power of 550-650 W in a pulse mode (on for 1.5-2.5 s and off for 0.5-1.5 s) for 1.5-2.5 min to obtain a homogeneous slurry;

[0046] filtering the homogeneous slurry through a nylon filter screen with a pore size of 90-110 μm and a metal sintered screen with a pore size of 18-22 μm in sequence at a filtration pressure of 0.25-0.35 MPa to obtain a coating liquid.

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

[0048] In some embodiments, step S3 comprises:

[0049] S31, coating the slurry using a precision slot die coater, the substrate running speed being 1.8-2.2 m / min, and the wet film thickness being 27-29 μm;

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

[0051] In step S3, the slurry leveling time is controlled by the precision slot die coater at a substrate running speed of 1.8-2.2 m / min, and the coating volume is accurately regulated in combination with a wet film thickness of 27-29 μm, so that the phosphoric acid ester modified epoxy resin and the silicone rubber microspheres are uniformly distributed, and coating stripes and microsphere agglomeration are avoided.

[0052] Further, three-stage curing is adopted: in the pre-curing stage, low-boiling-point solvents (such as propylene glycol methyl ether acetate) are preferentially volatilized, and the resin is pre-crosslinked; in the main curing stage, the methyl hexahydrophthalic anhydride curing agent is activated to achieve deep crosslinking; and in the final curing stage, the resin network is densified under nitrogen protection. This temperature-time synergistic mechanism not only ensures that the elastic structure of the silicone rubber microspheres is not damaged by high temperature, but also promotes the phosphonate groups to fully capture CO2 / H2O gas to form stable compounds, thereby realizing a bubble-free and elastic buffer function of the defoaming functional layer, and directly improving the integrity of the pattern during vacuum transfer.

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

[0054] The slurry ratio provides a gas-reactive matrix containing P=O groups through the phosphonate-modified epoxy resin, forms a crosslinked network with the methyl hexahydrophthalic anhydride curing agent at low temperature, and disperses the silicone rubber microspheres in a specific ratio to form a continuous elastic buffer phase; after the slurry is coated into a film, the phosphonate groups can chemically capture gas molecules such as CO2 / H2O to form stable phosphate compounds, and the silicone rubber microspheres absorb the expansion energy of the bubbles in the vacuum environment through elastic deformation to inhibit the growth and rupture of the bubbles, and the middle-layer solvent regulates the viscosity of the system to ensure uniform dispersion of the microspheres. The three work together to form a dense middle layer with gas elimination and mechanical buffering functions after curing, directly solving the pattern distortion problem caused by bubbles during transfer, and improving the edge definition of the transferred pattern.

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

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

[0057] Methyl hexahydrophthalic anhydride curing agent 26-30 parts by mass, leveling agent 0.7-0.9 parts by mass, and defoaming agent 0.4-0.6 parts by mass are added to the resin solution, and stirred at 750-850 rpm for 4-6 min;

[0058] The silicone rubber microspheres 16-20 parts by mass are added in 3-5 batches, and each batch is stirred at 1100-1300 rpm for 2.5-3.5 min after addition, and the temperature is controlled to be ≤40°C to obtain a pre-dispersed mixture;

[0059] The pre-dispersed mixture is input into a horizontal sand mill, and zirconia beads (diameter

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

[0061] The dispersion slurry is obtained by circulating 2-4 times under the conditions of rotor linear speed 9-11 m / s and feed speed 14-16 L / min, with the outlet temperature controlled to be ≤50℃;

[0062] The dispersion slurry is defoamed under a vacuum degree of -0.09 to -0.1 MPa for 25-35 min, so that the gas content is <0.5%;

[0063] The defoaming functional slurry is obtained by sequentially filtering through a 100-μm nylon filter screen and a 20-μm metal sintered screen.

[0064] In some embodiments, step S4 comprises:

[0065] S41, spraying the suspension using an ultrasonic electrostatic spraying system, with a spray gun voltage of +23 to +27 kV, a substrate bias voltage of -4 to -6 kV, a flow rate of 7.2-8.8 mL / min, and an atomization gas pressure of 0.11-0.13 MPa;

[0066] S41, spraying the suspension using an ultrasonic electrostatic spraying system, with a spray gun voltage of +23 to +27 kV, a substrate bias voltage of -4 to -6 kV, a flow rate of 7.2-8.8 mL / min, and an atomization gas pressure of 0.11-0.13 MPa;

[0067] S42, drying and activating, including infrared hot air drying at a temperature of 55-65℃ for 35-45 s, and vacuum activation at a pressure of -0.09 to -0.1 MPa for 20-30 s.

[0068] In the electrostatic spraying process of step S4, the construction of the gas trapping layer is realized through the synergistic effect of ultrasonic atomization and high-voltage electrostatic field: the graphene aerogel microsphere suspension is charged and atomized by the +23 to +27 kV positive voltage applied by the spray gun, and the directional electric field attraction is formed by the -4 to -6 kV negative bias voltage of the substrate, which, in combination with the 0.11-0.13 MPa atomization gas pressure, uniformly disperses the microspheres into a monolayer of droplets, and the flow rate of 7.2-8.8 mL / min ensures the microsphere deposition density per unit area, thereby forming a continuous distribution of micro-pore arrays on the coating surface; the subsequent 55-65℃ infrared hot air drying for 35-45 s selectively removes the surface free water but retains the internal bound water of the microspheres, and then the vacuum activation at -0.09 to -0.1 MPa for 20-30 s causes the microsphere closed structure to expand and open, forming through pores of 0.05-0.5 μm. The combination of this process increases the porosity of the microspheres to more than 93%, and the specific surface area reaches 620 m 2 / g, which efficiently traps the CO2 / H2O gas molecules released during the vacuum transfer process through the physical adsorption mechanism, while the optimization of the electrostatic parameters avoids the defects of the coating caused by the agglomeration of the microspheres, and finally realizes the reduction of the bubble residue 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 dispersant, 0.1-0.2 wt% of wetting agent, and the balance of deionized water.

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

[0071] In the suspension formula of step S4, graphene aerogel microspheres (GAMs) are used as gas capture cores at a concentration of 6-8 wt%, providing physical adsorption sites through their 0.05-0.5 μm pore size structure; dispersant BYK-190 containing polyurethane block copolymer is added at 0.2-0.4 wt% to maintain microsphere dispersion stability through steric hindrance effect, preventing nozzle clogging or forming coating defects during spraying due to agglomeration; acetylenic diol wetting agent Dynol 604 is added at 0.1-0.2 wt% to reduce the surface tension of the suspension to ≤30 mN / m, improving the wetting and spreading properties of the middle layer of epoxy resin coating, and ensuring uniform arrangement of the microsphere monolayer. The combination of the formula makes the microspheres remain in an isolated and dispersed state during electrostatic spraying, forming a continuous and open microporous network per unit area, when CO2 / H2O gas generated by vacuum transfer diffuses to the upper layer, it is efficiently captured and latched by the high specific surface area structure of the microspheres, while the wetting agent eliminates the interfacial tension difference, avoiding the generation of new gas bubbles during the drying process, and finally realizing zero-defect construction of the gas capture layer, 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 at a mass ratio of 1:2.8-1:3.2, and alternately treating by ultrasonic and centrifugal, ultrasonic frequency 38-42 kHz, centrifugal speed 2800-3200 rpm, for 2-4 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 ℃ for 1.5-2.5 h, then flash freezing at -190 to -200 ℃ for 8-12 min, and cooling from -5 ℃ to -40 ℃ at a cooling rate of 0.8-1.2 ℃ / min, to obtain a freeze-formed body;

[0075] S45, reducing the freeze-formed body in hydriodic acid (concentration 5 wt%), solution pH 2.5-3.5, temperature 50 ℃, time 2 h, to obtain a reduction product;

[0076] S46, drying the reduction product under supercritical CO2 conditions, pressure 7.3-7.5 MPa, temperature 30.5-31.5℃, time 3.5-4.5 h, pressure release rate 0.08-0.12 MPa / min, to obtain graphene aerogel microspheres.

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

[0078] The graphene aerogel microspheres are designed to have a pore size of 0.05-0.5 μm, matching the bubble size distribution in vacuum transfer printing, to achieve efficient physical trapping; the specific surface area of ≥550 m 2 / g provides a large number of gas adsorption sites, locking CO2 / H2O molecules through van der Waals force; the bulk density of ≤0.06 g / cm 3 ensures that the microspheres form an open network structure, avoiding the influence of coating thickening on transfer printing precision; and the concentration of 0.08-0.12 mol / L of the hydriodic acid mildly reduces graphene oxide in a pH = 3 environment, preserving the integrity of the microsphere skeleton and restoring the electrical conductivity of graphene, and the synergistic effect enables the gas trapping layer to maintain porosity while having anti-static adsorption capacity, eliminating edge blur defects caused by impurity adhesion in transfer printing patterns.

[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%-95%, the volume fraction of O2 is 5%-15%, the power density of the plasma treatment is 0.7-0.9 W / cm 2 , the treatment pressure is atmospheric pressure, the treatment speed is 2.5-3.5 m / min, and the interelectrode distance is 1.5-2.5 mm.

[0080] By using a mixture of He and O2 to perform plasma treatment at atmospheric pressure, wherein He is used as the main gas to generate high-density uniform plasma, and the active oxygen radicals generated by ionization of O2 react with the carbon-hydrogen chains on the surface of the PO substrate to form polar groups such as hydroxyl groups and carboxyl groups, and at the same time, the power density of 0.7-0.9 W / cm 2 ensures that the plasma penetration depth covers the surface layer of the substrate by 0.1-0.3 μm, under the premise of avoiding thermal damage to the substrate; in combination with the synergistic control of the treatment speed of 2.5-3.5 m / min and the interelectrode distance of 1.5-2.5 mm, the plasma residence time and action distance are balanced optimally, and a uniformly distributed micro-rough structure is constructed on the surface of the PO, thereby significantly enhancing the chemical bonding strength between the substrate and the lower coating (Zn 2+(Coordination with -COOH) and mechanical intercalation eliminate interfacial gas adsorption sites from the source, reducing the probability of bubble nucleation in subsequent coating processes.

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

[0082] By controlling the hot-pressing temperature to 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, tightly encapsulating the Primer layer. Simultaneously, a pressure of 0.7–0.9 MPa, while avoiding crushing the middle layer of silicone rubber microspheres, promotes the molten CPP / PE to penetrate into the gaps between the upper layer of graphene aerogel microspheres, forming a physical sealing layer. Combined with a hot-pressing time of 40–50 seconds and a roller speed of 1.4–1.6 m / min, it ensures sufficient diffusion of interlayer molecular chains without causing excessive shrinkage of the PO substrate. The subsequent low-temperature curing at 35–45°C for 22–26 hours allows residual stress between layers to be slowly released through the polymer chain segments, while inhibiting moisture intrusion that could cause interfacial debonding. Ultimately, the four-layer structure is permanently composited in a zero-bubble state, ensuring no risk of interfacial peeling during the transfer process.

[0083] This application also provides a high-performance PO composite film for OMR vacuum transfer, which is obtained based on the preparation method of any one of the foregoing.

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

[0085] The PET layer provides rigid support and laser micropore 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] The lower coating layer, 2.7–3.3 μm thick, within the Primer layer ensures the continuous flow of nano-SiO2 microporous channels (0.1–0.5 μm in diameter), while the middle coating layer, 11–12 μm thick, accommodates a sufficient quantity of silicone rubber microspheres. Constructing an elastic buffer network, an 8–10 μm upper coating enables the graphene aerogel microspheres to... Form a high porosity (≥93%) capture layer, the thickness system promotes the melt CPP / PE layer to fill the upper layer of microspheres gap fully when hot pressing composite, while avoiding the PO layer too thick to hinder heat transfer or the PET layer too thin to cause the release film to tear, finally realizing the zero gas residue and stress uniform distribution between layers in the transfer process, guaranteeing high-precision pattern transfer without distortion.

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

[0088] Example 1

[0089] The present example provides a preparation method of 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, a mixed gas of He and O2 is used, the volume fraction of He is 90%, the volume fraction of O2 is 10%, the power density of plasma treatment is 0.8 W / cm 2 , the treatment pressure is atmospheric pressure, the treatment speed is 3.0 m / min, the interelectrode distance is 2.0 mm, and the surface tension of the PO substrate after treatment is increased to above 42 mN / m.

[0091] S2, coating a lower layer coating on the pretreated PO substrate. First, prepare a coating liquid: mix 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 lower layer solvent (isopropyl alcohol), and after high-speed shearing dispersion and ultrasonic homogenization, filter to obtain the coating liquid. Then, use a micro-gravure coater to coat the coating liquid, the screen line number is 180 meshes, and the wet film thickness is 10.0 μm; perform infrared drying, the drying temperature is 70°C, and the drying time is 20 s; perform UV curing, the irradiation intensity is 120 mW / cm 2 , the cumulative dose is 600 mJ / cm 2 , to obtain a lower layer coating with a thickness of about 3.0 μm.

[0092] S3, coating a middle layer coating on the lower layer coating. First, prepare a slurry: take 100 parts by mass of phosphate ester modified epoxy resin, 18 parts by mass of silicone rubber microspheres, 28 parts by mass of methylhexahydrophthalic anhydride curing agent, and 120 parts by mass of middle layer solvent (propylene glycol methyl ether acetate), and after pre-dispersion and sanding dispersion, defoaming and filtering. Then, use a precision slot coater to coat the slurry, the substrate walking speed is 2.0 m / min, and the wet film thickness is 28 μm; perform step curing, including a pre-curing stage temperature of 80°C for 3.0 min, a main curing stage temperature of 100°C for 2.0 min, and a final curing stage temperature of 120°C for 2.0 min, to obtain a middle layer coating with a thickness of about 11.5 μm.

[0093] S4, spraying the upper layer coating on the middle layer coating. First, graphene aerogel microspheres are prepared: mixing the graphene oxide dispersion solution and polymethyl methacrylate microspheres at a mass ratio of 1:3.0, and alternately treating by ultrasonic and centrifugation (ultrasonic frequency 40 kHz, centrifugal speed 3000 rpm, cycle 3 times) to obtain a self-assembled mixture; after pre-freezing the mixture at -20℃ for 2.0 h, flash freezing at -195℃ for 10 min, and cooling from -5℃ to -40℃ at a cooling rate of 1.0℃ / min, a freeze-formed body is obtained; the freeze-formed body is reduced in a hydriodic acid solution, the solution pH value is 3.0, the temperature is 50℃, and the time is 2 h to obtain a reduction product; the reduction product is dried under supercritical CO2 conditions, the pressure is 7.4 MPa, the temperature is 31℃, the time is 4.0 h, and the pressure release rate is 0.1 MPa / min to obtain graphene aerogel microspheres. Then, a suspension is prepared: graphene aerogel microspheres 1.8 wt%, dispersant (BYK-190) 0.3 wt%, wetting agent (Dynol 604) 0.15 wt%, and the balance is deionized water. Then, the suspension is sprayed using an ultrasonic electrostatic spraying system, the spray gun voltage is +25 kV, the substrate bias voltage is -5 kV, the flow rate is 8.0 mL / min, and the atomizing gas pressure is 0.12 MPa; drying and activation are performed, including infrared hot air drying at a temperature of 60℃ for 40 s, vacuum activation at a pressure of -0.095 MPa for 25 s, to obtain an upper layer coating with a thickness of about 3.5 μm.

[0094] S5, post-curing the upper layer coating, the hot air circulation temperature is 130℃, and the time is 90 s, to obtain a cured Primer layer composed of the lower layer coating, the middle layer coating and the upper layer coating, and the total thickness is about 23.5 μm.

[0095] S6, sequentially stacking a PET layer (thickness about 255 μm), a PO layer (thickness about 100 μm), the cured Primer layer and a CPP / PE layer (thickness about 30 μm), and performing hot pressing compounding, the hot pressing temperature is 115℃, 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 maturing, the maturing temperature is 40℃, the maturing time is 24 h, and the maturing environment relative humidity is ≤30%, to finally obtain an OMR vacuum transfer high-performance PO composite film.

[0096] Example 2

[0097] The present embodiment provides a preparation method of an OMR vacuum transfer high-performance PO composite film, 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, a mixed gas of He and O2 is used, the volume fraction of He is 95%, the volume fraction of O2 is 5%, the power density of plasma treatment is 0.9 W / cm 2 , the treatment pressure is atmospheric pressure, the treatment speed is 3.5 m / min, the inter-electrode distance is 2.5 mm, and the surface tension of the PO substrate after treatment is increased to above 42 mN / m.

[0099] S2, coating a lower layer coating on the pretreated PO substrate. First, a coating liquid is prepared: 110 parts by mass of zinc acrylate, 6 parts by mass of nano-SiO2, 3.0 parts by mass of a photoinitiator 184, and 160 parts by mass of a lower layer solvent (isopropyl alcohol) are mixed, and after high-speed shearing dispersion and ultrasonic homogenization, filtration is performed to obtain the coating liquid. Then, the coating liquid is coated using a micro-gravure coater, the screen line number is 190 meshes, and the wet film thickness is 10.5 μm; infrared drying is performed at a drying temperature of 75°C for 25 s; UV curing is performed at an irradiation intensity of 130 mW / cm 2 , and a cumulative dose of 650 mJ / cm 2 , to obtain a lower layer coating with a thickness of about 3.0 μm.

[0100] S3, coating a middle layer coating on the lower layer coating. First, a slurry is prepared: 105 parts by mass of a phosphate ester modified epoxy resin, 20 parts by mass of silicone rubber microspheres, 30 parts by mass of a methylhexahydrophthalic anhydride curing agent, and 130 parts by mass of a middle layer solvent (propylene glycol methyl ether acetate) are pre-dispersed and sand-milled, and then defoaming filtration is performed. Then, the slurry is coated using a precision slot coater, the substrate speed is 2.2 m / min, and the wet film thickness is 29 μm; step curing is performed, including a pre-curing stage at a temperature of 85°C for 3.5 min, a main curing stage at a temperature of 105°C for 2.5 min, and a final curing stage at a temperature of 125°C for 2.5 min, to obtain a middle layer coating with a thickness of about 11.5 μm.

[0101] S4, spraying the upper layer coating on the middle layer coating. First, graphene aerogel microspheres are prepared: mixing the graphene oxide dispersion liquid and polymethyl methacrylate microspheres at a mass ratio of 1:3.2, and alternately treating by ultrasonic and centrifugation (ultrasonic frequency 42 kHz, centrifugal speed 3200 rpm, cycle 4 times) to obtain a self-assembled mixture; the mixture is pre-frozen at -18℃ for 1.5 h, then flash frozen at -190℃ for 8 min, and then cooled from -5℃ to -40℃ at a cooling rate of 1.2℃ / min to obtain a freeze-formed body; the freeze-formed body is reduced in a hydriodic acid solution, the pH value of the solution is 2.5, the temperature is 50℃, and the time is 2 h to obtain a reduction product; the reduction product is dried under supercritical CO2 conditions, the pressure is 7.5 MPa, the temperature is 31.5℃, the time is 4.5 h, and the pressure release rate is 0.12 MPa / min to obtain graphene aerogel microspheres. Then, a suspension is prepared: graphene aerogel microspheres 2.1wt%, dispersant (BYK-190) 0.4wt%, wetting agent (Dynol 604) 0.2wt%, and the balance is deionized water. Then, the suspension is sprayed using an ultrasonic electrostatic spraying system, the spray gun voltage is +27 kV, the substrate bias voltage is -6 kV, the flow rate is 8.8 mL / min, and the atomizing gas pressure is 0.13 MPa; drying and activation are performed, including infrared hot air drying at a temperature of 65℃ for 45 s, and vacuum activation at a pressure of -0.1 MPa for 30 s, to obtain an upper layer coating with a thickness of about 3.5μm.

[0102] S5, post-curing the upper layer coating, the hot air circulation temperature is 135℃, and the time is 100 s, to obtain a cured Primer layer composed of the lower layer coating, the middle layer coating and the upper layer coating, and the total thickness is about 23.5μm.

[0103] S6, sequentially stacking a PET layer (thickness about 255μm), a PO layer (thickness about 100μm), the cured Primer layer and a CPP / PE layer (thickness about 30μm), and performing hot press compounding, the hot press temperature is 120℃, the hot press pressure is 0.9 MPa, the hot press time is 50 s, and the hot press roller speed is 1.6 m / min; then maturing, the maturing temperature is 45℃, the maturing time is 26 h, and the maturing environment relative humidity is ≤30%, to finally obtain an OMR vacuum transfer high-performance PO composite film.

[0104] Example 3

[0105] The present embodiment provides a preparation method of an OMR vacuum transfer high-performance PO composite film, 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, a mixed gas of He and O2 is used, the volume fraction of He is 85%, the volume fraction of O2 is 15%, the power density of plasma treatment is 0.7 W / cm 2 , the treatment pressure is atmospheric pressure, the treatment speed is 2.5 m / min, the inter-electrode distance is 1.5 mm, and the surface tension of the PO substrate after treatment is increased to above 42 mN / m.

[0107] S2, a lower coating is coated on the pretreated PO substrate. First, a coating liquid is prepared: 90 parts by mass of zinc acrylate, 4 parts by mass of nano-SiO2, 2.0 parts by mass of a photoinitiator 184, and 140 parts by mass of a lower solvent (isopropyl alcohol) are mixed, and after high-speed shearing dispersion and ultrasonic homogenization, the coating liquid is obtained by filtration. Then, the coating liquid is coated using a micro-gravure coater, the screen line number is 170 meshes, and the wet film thickness is 9.5 μm; infrared drying is performed at a drying temperature of 65°C for 15 s; UV curing is performed at an irradiation intensity of 110 mW / cm 2 , and a cumulative dose of 550 mJ / cm 2 , to obtain a lower coating with a thickness of about 3.0 μm.

[0108] S3, a middle layer coating is coated on the lower layer coating. First, a slurry is prepared: 95 parts by mass of a phosphate-modified epoxy resin, 16 parts by mass of a silicone rubber microsphere, 26 parts by mass of a methylhexahydrophthalic anhydride curing agent, and 110 parts by mass of a middle layer solvent (propylene glycol methyl ether acetate) are pre-dispersed and sand-milled, then degassed and filtered. Then, the slurry is coated using a precision slot coater, the substrate speed is 1.8 m / min, and the wet film thickness is 27 μm; step curing is performed, including a pre-curing stage at 75°C for 2.5 min, a main curing stage at 95°C for 1.5 min, and a final curing stage at 115°C for 1.5 min, to obtain a middle layer coating with a thickness of about 11.5 μm.

[0109] S4, spraying the upper layer coating on the middle layer coating. First, graphene aerogel microspheres are prepared: mixing the graphene oxide dispersion solution and polymethyl methacrylate microspheres at a mass ratio of 1:2.8, and alternately treating by ultrasonic and centrifugation (ultrasonic frequency 38 kHz, centrifugal speed 2800 rpm, cycle 2 times) to obtain a self-assembled mixture; the mixture is pre-frozen at -22℃ for 2.5 h, then flash frozen at -200℃ for 12 min, and then cooled from -5℃ to -40℃ at a cooling rate of 0.8℃ / min to obtain a freeze-formed body; the freeze-formed body is reduced in a hydroiodic acid solution, the solution has a pH value of 3.5, a temperature of 50℃, and a time of 2 h to obtain a reduction product; the reduction product is dried under supercritical CO2 conditions, a pressure of 7.3 MPa, a temperature of 30.5℃, a time of 3.5 h, and a pressure release rate of 0.08 MPa / min to obtain graphene aerogel microspheres. Then, a suspension is prepared: graphene aerogel microspheres 1.5 wt%, dispersant (BYK-190) 0.2 wt%, wetting agent (Dynol 604) 0.1 wt%, and the balance being deionized water. Then, the suspension is sprayed using an ultrasonic electrostatic spraying system, the spray gun voltage is +23 kV, the substrate bias voltage is -4 kV, the flow rate is 7.2 mL / min, and the atomizing gas pressure is 0.11 MPa; drying and activation are performed, including infrared hot air drying at a temperature of 55℃ for 35 s, and vacuum activation at a pressure of -0.09 MPa for 20 s, to obtain an upper layer coating with a thickness of about 3.5 μm.

[0110] S5, post-curing the upper layer coating, the hot air circulation temperature is 125℃, and the time is 80 s, to obtain a cured Primer layer composed of the lower layer coating, the middle layer coating and the upper layer coating, and the total thickness is about 23.5 μm.

[0111] S6, sequentially stacking the PET layer (thickness about 255 μm), the PO layer (thickness about 100 μm), the cured Primer layer and the CPP / PE layer (thickness about 30 μm), and performing hot press compounding, the hot press temperature is 110℃, the hot press pressure is 0.7 MPa, the hot press time is 40 s, and the hot press roller speed is 1.4 m / min; then maturing, the maturing temperature is 35℃, the maturing time is 22 h, and the maturing environment relative humidity is ≤30%, to finally obtain an OMR vacuum transfer high-performance PO composite film.

[0112] Comparative Example 1

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

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

[0115] Comparative Example 2

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

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

[0118] Comparative example 3

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

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

[0121] Comparative example 4

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

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

[0124] Comparative example 5

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

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

[0127] The performance of the high-strength and high-density quartz composite material prepared by the method provided in the above examples and comparative examples is tested, and the test method is:

[0128] 1. Bubble defect rate

[0129] Test method: take a 10 cm x 10 cm composite film sample and place it on an LED backlight detection table (illuminance 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 ≥5 μm, and calculate the defect rate per unit area: Bubble defect rate (pieces / cm 2 ) = total bubble number / detection area (100 cm 2 ).

[0130] 2. Transfer pattern edge definition

[0131] Test method: The composite film was used for vacuum transfer of a standard test pattern (grid with line width 100 pm), transfer pressure -0.08 MPa, temperature 120 °C, time 30 s. The sawtooth offset of the line edge after transfer was measured using an ordinary optical microscope (Olympus BX43), and the average value of 10 lines was taken: edge offset (pm) = |design line width - actual line width|.

[0132] 3. Interlayer peeling strength

[0133] Test method: According to GB / T 2792-2014 standard, the non-composite surface of the PET layer and the non-composite surface of the CPP / PE layer of the composite film sample (150 mm x 25 mm) were adhered to two rigid metal clamp plates with quick curing epoxy adhesive, the adhesive layer thickness was ≤0.1 mm, and after curing at room temperature for 20 minutes, it was loaded into a tensile equipment; the upper clamp clamped the PET side metal plate, and the lower clamp clamped the CPP / PE side metal plate, and 90° vertical peeling was carried out at a speed of 100 mm / min, the initial 25 mm was a pre-peeling section, and the subsequent 100 mm effective section data was used to calculate the peeling strength (N / 25 mm). The peeling force peak value was recorded: peeling strength (N / 25 mm) = average peeling force / sample width.

[0134] Table 1 Performance test results

[0135] Group Bubble defect rate (number / cm 2 )]]> Edge offset (pm) Peeling strength (N / 25 mm) 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] Analysis of experimental results

[0137] In Example 1, plasma He / O2 = 90% / 10%, coating mesh 180, step curing 80-120 °C were used, and the bubble defect rate was only 0.8 / cm 2 , indicating that the gas escape channel was complete and the three-stage defoaming synergistic effect was sufficient; the transfer edge offset of 3.2 pm verified the effective inhibition of the coating on the bubble expansion, ensuring the pattern accuracy; the peeling strength of 4.5 N / 25 mm indicated that the plasma treatment and hot pressing (115 °C / 0.8 MPa) formed a strong interfacial bonding. It is shown that the parameter combination achieves an optimal balance in eliminating bubbles, maintaining transfer quality and enhancing interlayer bonding.

[0138] In Example 2, He 95%, mesh 190, and curing temperature 125 °C were used, and the bubble defect rate increased slightly to 1.1 / cm 2, which might be related to the shortened plasma exposure time or the partial closure of micropores caused by high-temperature curing at a high processing speed (3.5 m / min); the edge shift of 3.6 pm still indicated a high precision, which reflected that the electrostatic spraying parameters (+27 kV / -6 kV) could still ensure the uniform distribution of graphene microspheres; the slight decrease in the peeling strength of 4.3 N / 25 mm or the accelerated aging of the PO layer caused by hot pressing at 120 °C, but the extension of the curing time to 26 h compensated for the release of interlayer stress. It showed that the performance under the limit parameters was still better than that of the comparative examples.

[0139] In Example 3, the bubble defect rate increased to 1.3 per cm under He 85%, mesh 170, and curing temperature 115 °C 2 , which was caused by the incomplete volatilization of the solvent in the lower layer due to the low processing speed (2.5 m / min), and the residual trace of gas; the edge shift of 4.0 pm indicated that the thinning of the coating thickness (9.5 pm) slightly weakened the gas escape efficiency; but the peeling strength of 4.1 N / 25 mm verified the reasonable control of the low-temperature hot pressing (110 °C) on the melt flowability of CPP / PE, avoiding the crushing of the microsphere structure in the middle layer. It showed that even the conservative process could still maintain the functional integrity, highlighting the robustness of the method.

[0140] Comparative Example 1 adopted the measure of no plasma treatment, and the bubble defect rate increased to 5.6 per cm 2 , which indicated that the PO substrate surface did not form polar groups and micro-rough structures, resulting in insufficient adhesion of the lower coating, and the interface gas could not escape effectively; the edge shift of 8.5 pm indicated that the interface bubble expansion was not inhibited during transfer; after hot pressing and composite, when testing the peeling strength, the PO substrate was not firmly combined with the Primer layer due to the lack of plasma treatment, which caused the PO substrate to be taken with the PET layer when the PET layer was peeled off, and the interlayer peeling of the PO substrate and the Primer layer occurred, resulting in a significant decrease in the peeling strength, which confirmed the lack of chemical bonding between the substrate and the coating.

[0141] Comparative Example 2 lacked nano-SiO2 in the lower layer, resulting in a bubble defect rate of 4.2 per cm 2 , which was significantly higher than that of Example 1 (0.8), because the lack of 0.1-0.5 pm micropore channels, the gas could not escape during the infrared drying stage; the edge shift of 6.8 pm reflected that the bubbles were not eliminated in time after nucleation, which interfered with the transfer precision. But the peeling strength of 3.9 N / 25 mm was close to that of the example, which indicated that this defect mainly affected the defoaming function rather than the interfacial bonding.

[0142] Comparative Example 3 lacked silicone rubber microspheres in the middle layer, resulting in an edge shift of 12.3 pm, which was much higher than that of other comparative examples, proving that after the middle layer lost the elastic buffering ability, the bubble expansion energy in the vacuum environment directly destroyed the pattern integrity; the bubble defect rate was 3.5 per cm 2The chemical capture (phosphate group) is partially effective, but cannot compensate for the lack of mechanical energy buffer. The peel strength of 4.0 N / 25 mm indicates that the modification has limited impact on the interlayer bonding.

[0143] The upper layer of Comparative Example 4 lacks graphene aerogel microspheres, resulting in a bubble defect rate of 3.0 per cm 2 and a simultaneous deterioration of the edge offset of 7.2 pm, indicating that the loss of the physical adsorption layer causes residual gas to be unable to be captured, especially during the vacuum activation stage, losing the pore opening mechanism; the peel strength of 4.1 N / 25 mm is not affected, confirming that this layer mainly undertakes the terminal gas capture function.

[0144] The post-curing of 140°C in Comparative Example 5 causes the peel strength to drop to 3.0 N / 25 mm, and the Primer layer is embrittled due to excessive crosslinking, and the CPP / PE molten layer cannot effectively penetrate the microsphere gap during hot pressing; the bubble defect rate is 2.5 per cm 2 and a slight increase in the edge offset of 5.0 pm, reflecting that high temperatures may damage the structure of the middle layer of silicone rubber microspheres, weakening the elastic buffer capacity.

[0145] In summary, Examples 1-3 simultaneously achieve excellent performance of a bubble defect rate of ≤1.3 per cm 2 , a transfer edge offset of ≤4.0 pm, and a peel strength of ≥4.1 N / 25 mm through plasma treatment combined with a three-layer coating (a lower layer containing micro-porous channels, an elastic buffer middle layer, and a high adsorption upper layer) and a precise temperature control process; while the comparative examples cause systematic performance degradation due to the absence of a single link (such as no plasma treatment, lack of nano-SiO2 micro-pores, lack of silicone rubber microspheres, or graphene microspheres) or parameter out-of-bounds (post-curing of 140°C), resulting in a bubble defect rate that increases by 275%-600% (up to 5.6 per cm 2 ), an edge offset that expands to 5.0-12.3 pm (Comparative Example 3 is three times that of Example 3), and a peel strength that drops 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 states that the present application is illustrated by the above examples to explain the detailed process flow of the present application, but the present application is not limited to the above detailed process flow, i.e. it does not mean that the present application must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a high-performance PO composite film for OMR vacuum transfer, characterized in that, Includes the following steps: S1. Plasma treatment is performed on the PO substrate to obtain a pretreated PO substrate; S2. A lower coating layer is applied to the pretreated PO substrate. The lower coating layer is formed by a coating liquid containing zinc acrylate, nano-SiO2, photoinitiator 184 and a lower solvent. After coating, the lower coating layer is obtained by infrared drying and UV curing. S3. Apply an intermediate coating layer on the lower coating layer. The intermediate coating layer is formed by a slurry containing phosphate-modified epoxy resin, silicone rubber microspheres, methyl hexahydrophthalic anhydride curing agent and intermediate solvent. After coating, the intermediate coating layer is cured in stages to obtain the intermediate coating layer. S4. Spray an upper coating layer onto the middle coating layer. The upper coating layer is formed by a suspension containing graphene aerogel microspheres. After spraying, the upper coating layer is dried and activated under vacuum to obtain the upper coating layer. S5. The upper coating is post-cured with hot air circulation at a temperature of 125~135℃ for 80~100s to obtain a cured Primer layer consisting of a lower coating, a middle coating and an upper coating. S6. The PET layer, PO layer, cured primer layer and CPP / PE layer are stacked in sequence, hot-pressed and then cured to obtain the PO composite film. The slurry is prepared by the following method: Phosphate-modified epoxy resin and propylene glycol methyl ether acetate solvent were mixed at 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. Add 26-30 parts by weight of methylhexahydrophthalic anhydride curing agent, 0.7-0.9 parts by weight of leveling agent, and 0.4-0.6 parts by weight of defoamer to the resin solution, and stir at 750-850 rpm for 4-6 min; Add 16-20 parts by weight of silicone rubber microspheres in 3-5 batches. After each batch is added, stir at 1100-1300 rpm for 2.5-3.5 min and control the temperature to ≤40℃ to obtain a pre-dispersed mixture. The pre-dispersed mixture is fed into a horizontal sand mill, using zirconia beads (0.28~0.32mm in diameter, 65%~75% filling rate). The mixture was circulated 2-4 times under the conditions of rotor linear speed of 9m / ~11m / s and feed rate of 14L / ~16L / min, and the outlet temperature was controlled to be ≤50℃ to obtain the dispersed slurry. The dispersion slurry was degassed under a vacuum of -0.09 to -0.1 MPa for 25 to 35 minutes to reduce the gas content to <0.5%. The slurry was filtered sequentially through a 100μm nylon filter and a 20μm sintered metal mesh to obtain a defoaming slurry.

2. The preparation method according to claim 1, characterized in that, Step S2 includes: S21. Apply the coating liquid using a microgravure coating machine with a screen count of 170~190 mesh and a wet film thickness of 9.5~10.5μm; S22. Infrared drying, drying temperature is 65~75℃, drying time is 15~25s; S23, UV cured, irradiation intensity of 110~130mW / cm² 2 The cumulative dose is 550~650mJ / cm. 2 .

3. The preparation method according to claim 2, characterized in that, In step S2, the coating liquid contains the following components in parts 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 photoinitiator, and 140-160 parts by weight of lower layer solvent.

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

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

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

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

8. The preparation method according to claim 7, characterized in that, Step S4 further includes preparing the graphene aerogel microspheres: S43. Mix the graphene oxide dispersion with polymethyl methacrylate microspheres at a mass ratio of 1:2.8 to 1:3.2, and then treat the mixture with alternating ultrasonic and centrifugal processes. The ultrasonic frequency is 38 to 42 kHz, the centrifugal speed is 2800 to 3200 rpm, and the mixture is cyclically repeated 2 to 4 times to obtain a self-assembled mixture. S44. After pre-freezing the self-assembled mixture at -18~-22℃ for 1.5~2.5h, it is rapidly frozen at -190~-200℃ for 8~12min, and then cooled from -5℃ to -40℃ at a cooling rate of 0.8~1.2℃ / min to obtain a frozen molded body. S45. The frozen-formed body is reduced in hydroiodic acid at a pH of 2.5-3.5, a temperature of 50°C, and a time of 2 hours to obtain the reduction product. S46. The reduction product is dried under supercritical CO2 conditions at a pressure of 7.3~7.5MPa, a temperature of 30.5~31.5℃, a time of 3.5~4.5h, and a depressurization rate of 0.08~0.12MPa / 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 mixture of He and O2, wherein the volume fraction of He is 85%~95% and the volume fraction of O2 is 5%~15%, and the power density of the plasma treatment is 0.7~0.9 W / cm³. 2 The processing pressure is atmospheric pressure, the processing speed is 2.5~3.5m / min, and the electrode spacing is 1.5~2.5mm; In step S6, the hot pressing temperature is 110~120℃, the hot pressing pressure is 0.7~0.9MPa, the hot pressing time is 40~50s, the hot pressing roller speed is 1.4~1.6m / min, the curing temperature is 35~45℃, the curing time is 22~26h, and the relative humidity of the curing environment is ≤30%.

10. A high-performance PO composite film for OMR vacuum transfer, characterized in that, It is obtained based on the preparation method of any one of claims 1-9.