A pre-coat film preparation system
By using a multi-layer coating design and modular process in the pre-coated film preparation system, the problems of insufficient interfacial adhesion and surface energy stability are solved, achieving a balance between high adhesion and surface energy, thus meeting the needs of industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU SHUANGXING COLOR PLASTIC NEW MATERIALS
- Filing Date
- 2025-09-17
- Publication Date
- 2026-06-26
AI Technical Summary
Existing pre-coated films have shortcomings in terms of interfacial adhesion and surface energy stability. Traditional coating methods cannot achieve both high adhesion and surface energy, and coating uniformity and thickness control are difficult to guarantee, making it difficult to meet the needs of industrial production.
A pre-coated film preparation system is adopted, including modules such as roll unwinding, surface pretreatment, multilayer coating machine and hot air circulation drying tunnel. Through the synergistic design of interface adhesion enhancement layer and surface energy regulation layer, high-precision continuous coating is achieved. It is equipped with vacuum defoaming and ultrasonic mixing devices to ensure coating uniformity and stability.
It significantly improves the interfacial adhesion between the film and the hardened layer, electronic protective layer or insulating layer, ensuring the long-term stability of surface energy and the uniformity of the coating, and adapting to the industrial production needs of different film specifications.
Smart Images
Figure CN224405604U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of thin film coating and composite technology, specifically to a system for pre-coated thin film preparation. This system can achieve single-sided or double-sided coating, with uniform and controllable coating thickness. It features high efficiency, good stability, and adaptability to different film thicknesses, and is widely applicable to the industrial production of electronic protective films, insulating films, and hardened laminated films. Background Technology
[0002] Pre-coated films typically refer to films with adhesive or resin layers having specific functions coated on the surface of a film substrate, giving it the properties required for subsequent processing or lamination. With the continuous development of electronic displays, insulating materials, and optical components, films not only require excellent mechanical properties and transparency, but also need to form a stable and durable interfacial bond with hardened layers and functional coatings.
[0003] In the prior art, common pre-coated films generally use biaxially oriented films such as polyethylene terephthalate (PET) and polypropylene (PP) as substrates, improve their surface energy through corona treatment and plasma treatment, and then coat the substrate surface with a polyurethane (PU) adhesive layer to improve adhesion.
[0004] However, this method relies on physical modification to enhance interfacial activity, often resulting in insufficient durability. Due to the high crystallinity of polyester-based films and the lack of sufficient active groups on their surface, the bonding between the polyurethane coating and the substrate relies mainly on physical adsorption or structural roughening, making the interface prone to delamination under long-term damp heat or mechanical action. On the other hand, while corona or plasma treatment can increase surface energy in the short term, its effect gradually diminishes over time, making it difficult to maintain a consistently high surface energy value. Furthermore, traditional single-layer polyurethane coatings in practical applications need to simultaneously consider adhesion to the substrate, surface energy, and abrasion resistance. This superposition of multiple properties often leads to performance trade-offs, making it difficult to achieve a balance between high adhesion and surface stability. Therefore, how to significantly improve the adhesion between the coating and the substrate while maintaining film transparency and mechanical properties, and ensuring long-term surface energy stability through innovative interface design and process optimization, has become a pressing technical challenge.
[0005] Furthermore, existing pre-coated film production typically relies on manual or semi-automated coating equipment, making it difficult to fully guarantee coating uniformity, thickness control, and surface adhesion stability. Especially in applications requiring high adhesion and strict surface energy control, traditional coating methods suffer from the following problems: First, precise control of coating thickness leads to significant performance fluctuations in the interfacial adhesion enhancement layer and surface energy regulation layer; second, switching between single / double-sided coating is inconvenient, making it difficult to meet the flexible production needs of different product specifications; third, poor coordination between coating and drying processes, with uneven or over-drying affecting coating transparency, flexibility, and adhesion; and fourth, low coating dispersion and mixing efficiency, especially for composite coatings containing nanoparticles or low molecular weight epoxy resins, making it difficult to guarantee uniform particle distribution and stability.
[0006] Therefore, there is an urgent need for a pre-coated film preparation system that can achieve precise control of coating amount, high coating uniformity, adaptability to single / double-sided coating and different film specifications, and high efficiency and stability, in order to meet the needs of industrial continuous production and ensure that the surface adhesion, surface energy and durability of the final film product meet the expected standards. Summary of the Invention
[0007] The technical problem to be solved by this invention is to provide a pre-coated thin film preparation system to reduce or avoid the problems mentioned above.
[0008] To address the aforementioned technical problems, this utility model proposes a pre-coated film preparation system, comprising a roll unwinding device, a surface pretreatment device, a first coating machine, a first hot air circulating drying tunnel, a second coating machine, a second hot air circulating drying tunnel, and a cooling winding device connected in sequence. The roll unwinding device is used to carry and continuously unwind the substrate film; the surface pretreatment device is used to perform surface treatment on the unwound substrate surface; the first coating machine is used to uniformly coat an interfacial adhesion enhancement layer on the surface-treated substrate surface, and then the first hot air circulating drying tunnel dries the coated interfacial adhesion enhancement layer; the second coating machine is used to coat a surface energy regulation layer on the outside of the interfacial adhesion enhancement layer, and the second hot air circulating drying tunnel dries the surface energy regulation layer; the cooling winding device is used to cool the coated film and then wind it into a roll.
[0009] Preferably, the pre-coated film preparation system further includes a first coating liquid preparation tank and a second coating liquid preparation tank. The first coating liquid preparation tank is used to mix and prepare an interfacial adhesion enhancement layer coating liquid and transport it to a first coating machine through a pipeline. The second coating liquid preparation tank is used to mix and prepare a surface energy regulation layer coating liquid and transport it to a second coating machine through a pipeline.
[0010] Preferably, the first coating liquid preparation tank is equipped with a vacuum defoaming device; the second coating liquid preparation tank is equipped with an ultrasonic generator.
[0011] Preferably, the pre-coated film preparation system further includes a film flipping wheel assembly, a third coating machine, a third hot air circulating drying tunnel, a fourth coating machine, and a fourth hot air circulating drying tunnel, wherein the film flipping wheel assembly is used to flip the film; the third coating machine and the third hot air circulating drying tunnel are used to coat an interface adhesion reinforcement layer on the surface of the flipped film and then dry it; the fourth coating machine and the fourth hot air circulating drying tunnel are used to coat a surface energy regulation layer on the outside of the interface adhesion reinforcement layer and then dry it.
[0012] Preferably, the first coating liquid preparation tank simultaneously supplies coating liquid to the first coating machine and the third coating machine through a pipeline, and the second coating liquid preparation tank simultaneously supplies coating liquid to the second coating machine and the fourth coating machine through a pipeline, thereby achieving synchronous supply of coating liquid to both sides.
[0013] This invention provides a pre-coated film preparation system that achieves high-precision continuous coating of an interfacial adhesion enhancement layer and a surface energy regulation layer on a substrate surface. It boasts advantages such as uniform coating, controllable thickness, and stable adhesion exceeding 62 dynes, significantly enhancing the interfacial bonding between the film and the hardening layer, electronic protection layer, or insulating layer. The system utilizes a coating liquid preparation tank equipped with a vacuum defoaming or ultrasonic mixing device to improve the uniformity and density of the coating liquid, ensuring a smooth coating with stable surface properties. The double-sided preparation system employs a rotating wheel assembly and multi-channel pipeline delivery to achieve consistent and uniform double-sided coating, while simplifying pipeline layout and improving production continuity and operational stability. The overall system is modular and flexibly configurable, suitable for BOPET substrates of varying thicknesses, and can meet the needs of large-scale industrial production, thus providing high-performance basic materials for fields such as hardening, electronic protection, and insulating materials. Attached Figure Description
[0014] The accompanying drawings are intended only to illustrate and explain this application and do not limit the scope of this utility model.
[0015] Figure 1 The diagram shown is a structural schematic of a pre-coated film preparation system for a single-sided structure according to a specific embodiment of this application.
[0016] Figure 2 The diagram shown is a structural schematic of a pre-coated film preparation system for a double-sided structure according to another specific embodiment of this application. Detailed Implementation
[0017] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model will now be described in detail.
[0018] In view of the problems of insufficient adhesion and unstable surface energy of pre-coated films in the prior art, this invention proposes a pre-coated film and its preparation method. The pre-coated film is composed of a substrate, an interfacial adhesion enhancement layer, and a surface energy regulation layer, which are sequentially formed. The interfacial adhesion enhancement layer is attached to one or both surfaces of the substrate, while the surface energy regulation layer is located outside the interfacial adhesion enhancement layer. For a single-sided pre-coated film, the overall structure is a three-layer structure; for a double-sided pre-coated film, the above two coating layers are formed on both sides of the substrate, thus forming a five-layer structure.
[0019] The substrate is preferably a biaxially oriented polyethylene terephthalate (BOPET) film with a thickness ranging from 25 μm to 250 μm. By sequentially forming an interfacial adhesion enhancement layer and a surface energy modulation layer on one or both sides, the surface energy of the film can be stably maintained above 62 dynes, while significantly improving the interfacial bonding strength with functional layers such as the hardening layer, electronic protection layer, and insulating layer.
[0020] The interfacial adhesion enhancement layer is mainly composed of polyurethane resin and a silane modifier containing bifunctional groups. In the formulation, polyurethane provides flexibility and basic adhesion, while silane molecules form a molecular-level anchoring structure on the base film surface through condensation crosslinking, thereby significantly enhancing interfacial bonding. In a preferred embodiment, the interfacial adhesion enhancement layer is composed of the following components in parts by weight: 50-70 parts polyurethane acrylate, 20-30 parts low molecular weight epoxy resin, 5-10 parts 3-aminopropyltriethoxysilane, 2-5 parts dibutyl phthalate, and 5-15 parts isopropanol solvent.
[0021] The low molecular weight epoxy resin is preferably a bisphenol A type epoxy resin, such as Epikote 828 from Mitsubishi Chemical (Japan), Epon 828 from Hexion (USA), or E-51 from Bluestar (China). Its epoxy equivalent is preferably 180-200 g / eq, and its viscosity is between 5000-15000 mPa·s. This resin can synergistically work with polyurethane and silane coupling agents to improve the crosslinking density and adhesion of the interface layer. The coating thickness of this layer is controlled at 0.1-0.5 μm to ensure sufficient interfacial reaction without affecting the transparency of the base film.
[0022] The surface energy regulation layer is a dense layer formed by a composite of flexible polyether polyurethane and nano-inorganic particles, which can maintain high surface energy and significantly improve surface wear resistance and scratch resistance. In another preferred embodiment, the surface energy regulation layer is composed of the following components in parts by weight: 60-80 parts of polyether polyurethane, 3-8 parts of methyltriethoxysilane, 5-15 parts of nano-silica or alumina with a particle size of 10-50 nm, 5-10 parts of polyvinyl acetal, and 10-20 parts of ethanol / water mixed solvent. The polyether polyurethane, as the main film-forming material, has a solid content of 30-40 wt%, a number average molecular weight of 20,000-60,000, a viscosity controlled at 500-2000 mPa·s, and a glass transition temperature of -30 to -10°C, which can form a flexible, transparent coating with high surface energy on the film surface. Applicable products include Covestro's Bayhydrol UH series (Germany), Lubrizol's Sancure series (USA), Wanhua Chemical's WANNY series (China), or Mitsui Chemicals' Takelac series (Japan). The ethanol / water mixed solvent is preferably prepared by mixing anhydrous ethanol and deionized water at a volume ratio of 7:3. This ratio ensures both solubility and dispersibility while also considering the evaporation rate and film uniformity during the coating process. The coating thickness is controlled between 0.5 and 1.0 μm.
[0023] The pre-coated film of the present invention can be prepared by the following method. The method includes the following steps: First, the substrate film is pre-treated to increase the surface tension of the substrate to 50 dynes or more. The substrate is preferably a biaxially oriented polyethylene terephthalate (BOPET) film with a thickness ranging from 25 to 250 μm. Before coating, the substrate surface is subjected to corona treatment or plasma treatment to introduce polar groups and increase surface roughness, thereby improving the adhesion of the interfacial adhesion enhancement layer. For example, if corona treatment is used, the power of the corona treatment is typically controlled between 1.0 and 3.0 kW.
[0024] Next, prepare the interfacial adhesion enhancement layer coating solution. According to the formulation ratio, add polyurethane acrylate, low molecular weight epoxy resin, 3-aminopropyltriethoxysilane, and dibutyl phthalate sequentially to isopropanol solvent, and stir at 500-800 rpm for 30-60 minutes to ensure that all components are fully dissolved and uniformly mixed. If necessary, vacuum degassing can be performed under reduced pressure for 10-20 minutes to remove air bubbles from the solution and ensure the stability of the subsequent coating process.
[0025] The interfacial adhesion enhancement layer coating solution is applied to one or both sides of the treated substrate using a coating machine, employing either comma-type doctor blade coating or gravure coating methods. The coating amount is controlled between 0.5-2.0 g / m². The coated film is then dried in a hot air circulating oven. The oven temperature is controlled in stages between 80-120°C, and the film's residence time in the oven is 30-90 seconds (determined by the production line speed and oven length) to ensure sufficient solvent evaporation and promote the initial cross-linking reaction between the coating and the substrate surface, forming an interfacial adhesion enhancement layer with a thickness of 0.1-0.5 μm.
[0026] Next, prepare the surface energy modulation layer coating solution. According to the formulation ratio, add polyether-type polyurethane, methyltriethoxysilane, nano-silica or alumina particles, and polyvinyl acetal sequentially to an ethanol / water mixed solvent (ethanol to deionized water volume ratio 7:3). Stir at 800-1200 rpm for 40-80 minutes to ensure uniform dispersion. To avoid nanoparticle aggregation, further ultrasonic dispersion for 10-20 minutes can be used to obtain a stable and transparent coating solution.
[0027] The surface energy modulation layer coating liquid is applied to the surface of the interfacial adhesion reinforcement layer using a coating machine, which can be either precision blade coating or gravure coating. The coating amount is controlled at 1.0-3.0 g / m². The coated film is then dried in a hot air drying tunnel at a temperature of 90-130°C for 60-120 seconds to ensure complete solvent evaporation and to promote the condensation and crosslinking reaction between polyurethane molecules and the silane coupling agent under thermal conditions, thereby forming a dense and transparent composite layer on the surface with a thickness controlled at 0.5-1.0 μm.
[0028] Finally, after being cooled in the cooling zone, the resulting film is rolled up.
[0029] For single-sided pre-coated films, an interfacial adhesion enhancement layer and a surface energy modulation layer are formed on one side of the substrate. For double-sided pre-coated films, the above process is repeated on both sides of the substrate to form a double-layer coating structure on both sides of the substrate. The pre-coated film prepared by this process has a stable surface energy of over 62 dynes, a transparent and smooth surface, and excellent adhesion, which can meet the needs of various applications such as subsequent hardening, electronic protection, and insulation materials.
[0030] In line with the preparation process of this application, this utility model further proposes a pre-coated film preparation system specifically for this application, such as... Figure 1-2 As shown. Among them, Figure 1 The diagram shown is a schematic representation of a pre-coated film preparation system for a single-sided structure according to a specific embodiment of this application. Figure 2 The diagram shown is a structural schematic of a pre-coated film preparation system for a double-sided structure according to another specific embodiment of this application.
[0031] like Figure 1 As shown, the single-sided pre-coated film preparation system of this application includes a roll unwinding device 100, a surface pretreatment device 200, a first coating machine 300, a first hot air circulating drying tunnel 400, a second coating machine 500, a second hot air circulating drying tunnel 600, and a cooling winding device 700 connected in sequence. The roll unwinding device 100 is used to carry and unwind the BOPET substrate film, ensuring stable film tension during coating, and continuously feeding it into the surface pretreatment device 200. The surface pretreatment device 200 is used to perform corona treatment or plasma surface treatment on the substrate surface before coating to improve the surface activity and wettability of the substrate. The first coating machine 300 is used to uniformly coat the interfacial adhesion reinforcement layer on the surface-treated substrate surface, and then the first hot air circulating drying tunnel 400 dries the coated interfacial adhesion reinforcement layer to form a stable adhesion structure. The second coating machine 500 is used to coat a surface energy regulation layer on the outside of the interfacial adhesion enhancement layer. The second hot air circulating drying tunnel 600 dries the surface energy regulation layer to make the coating dense and uniform. The cooling and winding device 700 is used to cool the coated film to a suitable temperature and then wind it into a roll to ensure the integrity of the coating and the stability of the film tension.
[0032] Further as Figure 1 As shown, the pre-coated film preparation system of this application further includes a first coating liquid preparation tank 301 and a second coating liquid preparation tank 501, wherein the first coating liquid preparation tank 301 is used to mix and prepare the interfacial adhesion enhancement layer coating liquid and convey it to the first coating machine 300 through a pipeline; the second coating liquid preparation tank 501 is used to mix and prepare the surface energy regulation layer coating liquid and convey it to the second coating machine 500 through a pipeline.
[0033] In one specific embodiment, the first coating liquid preparation tank 301 is equipped with a vacuum defoaming device 302 to eliminate air bubbles in the coating liquid, thereby preventing the formation of pores or uneven coatings during the coating process and improving the density and adhesion of the coating. In another specific embodiment, the second coating liquid preparation tank 501 is equipped with an ultrasonic generator 502 to enhance the mixing uniformity of the coating liquid, ensuring sufficient dispersion of nanoparticles and polymer components, thereby significantly improving the uniformity, smoothness, and surface performance stability of the surface energy regulation layer. Through the above design, this system can significantly improve the preparation quality of the coating liquid, ensure consistent coating performance and high reliability, and facilitate continuous industrial production.
[0034] like Figure 2As shown, the double-sided pre-coated film preparation system of this application is an extension of the single-sided preparation system to achieve continuous coating processing on both sides of the substrate. The system includes, in sequence, a roll unwinding device 100, a surface pretreatment device 200, a first coating machine 300, a first hot air circulating drying tunnel 400, a second coating machine 500, a second hot air circulating drying tunnel 600, a film turning roller group 800, a third coating machine 310, a third hot air circulating drying tunnel 410, a fourth coating machine 510, a fourth hot air circulating drying tunnel 610, and a cooling winding device 700. The film turning roller group 800 is used to turn the continuously conveyed film over, facilitating coating on the other side of the film. The third coating machine 310 and the third hot air circulating drying tunnel 410 have the same structure and function as the first coating machine 300 and the first hot air circulating drying tunnel 400, mainly used to coat the interfacial adhesion reinforcement layer on the surface of the flipped film and then dry it. The fourth coating machine 510 and the fourth hot air circulating drying tunnel 610 have the same structure and function as the second coating machine 500 and the second hot air circulating drying tunnel 600, mainly used to coat the surface energy control layer on the outside of the interfacial adhesion reinforcement layer and then dry it. With the above configuration, the double-sided preparation system can ensure the uniformity of the coating on both sides, the controllability of the thickness, and the consistency of the adhesion.
[0035] Further as Figure 2 As shown, the double-sided pre-coated film preparation system of this application also includes a first coating liquid preparation tank 301 and a second coating liquid preparation tank 501. The first coating liquid preparation tank 301 is used to mix and prepare the interfacial adhesion enhancement layer coating liquid, and is simultaneously supplied to the first coating machine 300 and the third coating machine 310 through pipelines. The second coating liquid preparation tank 501 is used to mix and prepare the surface energy regulation layer coating liquid, and is simultaneously supplied to the second coating machine 500 and the fourth coating machine 510 through pipelines. Through the above design, the double-sided preparation system can realize the synchronous supply of coating liquids on both sides, ensuring the consistency and uniformity of the interfacial adhesion enhancement layer and the surface energy regulation layer in double-sided coating, which is beneficial to improving the adhesion and smoothness of the coating. At the same time, it simplifies the layout of liquid delivery pipelines, improves production continuity and operational stability, and facilitates large-scale industrial production.
[0036] Similarly, the first coating liquid preparation tank 301 can also be equipped with a vacuum defoaming device 302, and the second coating liquid preparation tank 501 can also be equipped with an ultrasonic generator 502, such as... Figure 2 As shown.
[0037] This invention proposes a pre-coated film preparation system capable of adapting to single-sided or double-sided coating processes, achieving high-precision continuous coating of the interfacial adhesion enhancement layer and the surface energy regulation layer on the substrate surface. The system organically combines modules such as a roll unwinding device, a surface pretreatment device, a coating machine and corresponding hot air circulating drying tunnel, a turning wheel assembly, and a cooling winding device, ensuring stable film tension, uniform coating, and controllable coating thickness during continuous conveying. The coating liquid preparation tank is equipped with a vacuum defoaming device or an ultrasonic mixing device to ensure uniform and bubble-free coating liquid for the interfacial adhesion enhancement layer and the surface energy regulation layer, thereby improving coating density, adhesion, and surface smoothness.
[0038] For double-sided coating, the system is designed with a rotating wheel assembly and multi-channel pipeline delivery, enabling simultaneous supply of coating liquid to both sides. This ensures consistency and uniformity in double-sided coating while simplifying pipeline layout and improving production continuity and operational stability. The overall system balances the flexibility of single-sided and double-sided coating processes, adapting to BOPET substrates with varying thicknesses and performance requirements, thus facilitating large-scale industrial production. Through coordinated control of each module, this system effectively improves the surface adhesion and functional layer performance of the pre-coated film, providing high-quality base materials for subsequent applications such as curing, electronic protection, and insulation.
[0039] Example 1
[0040] The substrate is a 25μm thick biaxially oriented polyethylene terephthalate (BOPET) film. The formulation of the interfacial adhesion reinforcement layer by weight is: 60 parts polyurethane acrylate, 25 parts low molecular weight bisphenol A epoxy resin, 8 parts 3-aminopropyltriethoxysilane (APTES), 3 parts dibutyl phthalate, and 10 parts isopropanol solvent. The thickness of this layer after coating is controlled to be 0.2μm. The formulation of the surface energy modulation layer by weight is: 70 parts polyether polyurethane, 5 parts methyltriethoxysilane (MPTES), 10 parts nano-silica with a particle size of about 20nm, 7 parts polyvinyl acetal, and 15 parts ethanol / deionized water mixed solvent (volume ratio 7:3). The surface layer coating thickness is controlled to be 0.6μm. In this embodiment, the substrate is first subjected to corona treatment (approximately 2.0 kW, which increases the surface tension to approximately 50 dynes or more). Then, an interfacial adhesion enhancement layer is applied to the substrate surface using a comma-shaped doctor blade (coating amount approximately 0.8-1.2 g / m²). The substrate is then dried in a hot air circulating oven at 90°C-100°C to allow the coating to undergo preliminary condensation cross-linking (dwell time in the oven approximately 45-60 seconds). Next, a surface energy modulation layer is applied to the surface using a precision doctor blade and dried and cured at 100°C-115°C (dwell time approximately 60-90 seconds). The resulting single-sided pre-coated film has a measurable surface energy of ≥62 dynes and is transparent and uniform.
[0041] Example 2
[0042] The substrate is BOPET with a thickness of 50 μm. The interfacial adhesion reinforcement layer consists of 55 parts polyurethane acrylate, 30 parts low molecular weight epoxy resin, 5 parts APTES, 4 parts dibutyl phthalate, and 12 parts isopropanol, with a coating thickness controlled at 0.3 μm. The surface energy modulation layer consists of 60 parts polyether polyurethane, 6 parts MPTES, 12 parts nano-alumina with a particle size of approximately 15 nm, 6 parts polyvinyl acetal, and 12 parts ethanol / water solvent, with a surface layer thickness of 0.8 μm. In this embodiment, gravure roller coating is preferentially used to obtain a more stable coating amount and a finer surface layer distribution. The interfacial layer is dried and initially reacted in an oven at 85-105℃ (holding time 40-70 seconds), and the surface layer completes film formation and thermal crosslinking at 105-120℃ (holding time 70-100 seconds). The resulting single-sided pre-coated film exhibits good interfacial stability under weathering and humid heat conditions, with a surface energy maintained at ≥62 dynes.
[0043] Example 3
[0044] The substrate is a 75 μm thick BOPET. The interfacial adhesion enhancement layer is formulated with 65 parts polyurethane acrylate, 22 parts low molecular weight epoxy resin, 6 parts APTES, 4 parts dibutyl phthalate, and 10 parts isopropanol, with a coating thickness controlled at 0.15 μm. The surface energy modulation layer consists of 65 parts polyether polyurethane, 4 parts MPTES, 8 parts nano-silica with a particle size of approximately 30 nm, 8 parts polyvinyl acetal, and 14 parts ethanol / water mixed solvent, with a surface layer thickness of approximately 0.5 μm. During the preparation process, the substrate surface is first treated with low-temperature plasma to activate surface functional groups. Then, the interfacial layer is coated with a doctor blade and dried at around 90°C to promote local condensation and grafting of silane with the base film surface and epoxy resin. The surface layer is then dried in a 95-110°C oven to complete film formation, and mild heat treatment promotes the formation of the MPTES condensation network. The resulting single-sided pre-coated film exhibits excellent interfacial adhesion durability in multiple damp heat cycles and peel tests.
[0045] Example 4
[0046] The substrate is BOPET with a thickness of 100μm. The formulation of the interface adhesion enhancement layer is set as follows: 50 parts polyurethane acrylate, 30 parts low molecular weight epoxy resin, 10 parts APTES, 2 parts dibutyl phthalate and 8 parts isopropanol, with a coating thickness controlled at 0.4μm. The formulation of the surface energy regulation layer is 60 parts polyether polyurethane, 8 parts MPTES, 15 parts nano alumina with a particle size of 10nm, 5 parts polyvinyl acetal and 10 parts ethanol / water solvent, with a surface layer thickness of 1.0μm. This embodiment enhances chemical anchoring by increasing the amount of APTES in the interface layer, while introducing a higher content of nano-inorganic fillers in the surface layer to improve surface abrasion resistance and insulation stability. The coating and drying processes adopt gravure coating and segmented hot air circulating drying tunnel (interface layer segment 90-110℃, surface layer segment 110-130℃, the dwell time of each segment is determined according to the line speed). The resulting single-sided pre-coated film exhibits excellent performance in terms of surface hardness, scratch resistance and long-term adhesion.
[0047] Example 5
[0048] The substrate uses BOPET with a thickness of 150 μm to balance mechanical strength and processing stability. The interfacial adhesion reinforcement layer consists of 70 parts polyurethane acrylate, 20 parts low molecular weight epoxy resin, 5 parts APTES, 3 parts dibutyl phthalate, and 12 parts isopropanol, with a coating thickness of approximately 0.25 μm. The surface energy modulation layer consists of 80 parts polyether polyurethane, 3 parts MPTES, 5 parts 50 nm nano-silica, 10 parts polyvinyl acetal, and 10 parts ethanol / water solvent, with the surface layer thickness controlled at 0.7 μm. In this embodiment, the dispersion of nanoparticles in the surface layer is prioritized during preparation (by ultrasonic dispersion for 10-20 minutes while maintaining moderate shear in the dispersion system). The interfacial layer is dried at 85-100℃, and the surface layer is cured at 100-115℃. Testing shows that this single-sided pre-coated film exhibits high surface energy (≥62 dynes), good transparency, and high surface abrasion resistance, making it suitable for applications requiring high mechanical protection.
[0049] Example 6
[0050] The substrate is BOPET with a thickness of 250μm. The formulation of the interfacial adhesion reinforcement layer is 58 parts polyurethane acrylate, 28 parts low molecular weight epoxy resin, 7 parts APTES, 4 parts dibutyl phthalate and 3 parts isopropanol, with the coating thickness controlled at the upper limit of 0.5μm. The surface energy regulation layer is composed of 62 parts polyether polyurethane, 6 parts MPTES, 10 parts nano alumina with a particle size of 18nm, 7 parts polyvinyl acetal and 20 parts ethanol / water solvent, with a surface layer thickness of 1.0μm. To ensure the film quality and interfacial bonding strength of the thick coating, this embodiment adopts a segmented heating method during the interface layer drying stage (first, solvent evaporation is carried out at 80-95℃, and then cross-linking is promoted at 100-110℃). The surface layer completes secondary cross-linking and densification treatment at 110-130℃. The resulting single-sided pre-coated film can still maintain a surface energy of ≥62 dynes under thick substrate conditions and the coating is firmly bonded. It is suitable for applications that require high mechanical support from the substrate and long-term stable adhesion.
[0051] Based on Examples 1-6, the interfacial adhesion enhancement layer and the surface energy modulation layer can be further coated simultaneously on the other side of the substrate to form a double-sided pre-coated structure. Actual preparation and testing revealed that the double-sided pre-coated film showed no significant difference from the single-sided pre-coated film in terms of interfacial adhesion, surface energy modulation effect, and overall durability; the relevant performance indicators remained essentially the same, with only slight improvements in flexibility and scratch resistance. Therefore, the following description of this invention primarily uses the single-sided pre-coated film for comparison and explanation, and will not provide repeated examples and comparative descriptions specifically for the double-sided coating structure.
[0052] Comparative Example 1
[0053] In Comparative Example 1, an interfacial adhesion enhancement layer was coated only on one side of the BOPET substrate with a thickness of 50 μm, without a surface energy modulation layer. The formulation of this interfacial adhesion enhancement layer was the same as in Example 1, and the coating thickness was maintained at 0.3 μm. Testing revealed that although this sample showed improved interfacial adhesion, the lack of a surface energy modulation layer resulted in a high surface energy, leading to excessively strong adhesion during subsequent adhesive bonding, resulting in adhesive residue and affecting the film's re-peelability and final performance.
[0054] Comparative Example 2
[0055] In Comparative Example 2, a surface energy modulation layer was coated only on one side of a 75 μm thick BOPET substrate, without an interfacial adhesion enhancement layer. The formulation of this surface energy modulation layer was consistent with that of Example 2, and the coating thickness was 0.8 μm. Test results showed that the sample exhibited significant surface energy modulation, demonstrating low surface energy and good antifouling properties. However, due to the lack of an interfacial adhesion enhancement layer, the surface layer of the film was prone to peeling off during use, resulting in poor coating durability.
[0056] Comparative Example 3
[0057] In Comparative Example 3, the BOPET substrate was 100 μm thick. One side was first coated with a conventional water-based acrylic coating as an inner layer, with a coating thickness of 0.3 μm, and then a surface energy modulation layer identical to that in Example 3 was coated on top of it. The test results showed that the surface energy modulation layer of this structure could still function, but due to the insufficient adhesion between the conventional coating and the substrate, the adhesion of the overall coating system decreased, and the film was prone to local delamination during thermal shock and bending tests.
[0058] Comparative Example 4
[0059] In Comparative Example 4, the substrate thickness was 125 μm. One side was first coated with the same interfacial adhesion enhancement layer as in Example 4, with a thickness of 0.2 μm. The surface energy modulation layer was replaced with ordinary polyurethane varnish, with a thickness of 0.6 μm. The results showed that the sample still had strong interfacial bonding force under the action of the adhesion enhancement layer. However, since the outer layer was a conventional varnish, it could not effectively reduce the surface energy, resulting in serious glue residue problems during the lamination process. Furthermore, the surface layer was significantly lacking in stain resistance and scratch resistance.
[0060] Comparative Example 5
[0061] In Comparative Example 5, the substrate thickness was 150 μm. The interfacial adhesion reinforcement layer coated on one side omitted 3-aminopropyltriethoxysilane (APTES) from the formulation. Other components and proportions remained consistent with Example 5, with a thickness of 0.4 μm. Test results showed that the lack of a silane coupling agent significantly weakened the interfacial bonding between the reinforcement layer and the BOPET substrate, leading to localized detachment of the outer layer during the peel test and a decrease in overall reliability.
[0062] Comparative Example 6
[0063] In Comparative Example 6, the substrate thickness was 200 μm. One side was coated with the same interfacial adhesion enhancement layer and surface energy modulation layer as in Example 6, but nano-silica was omitted from the surface energy modulation layer formulation. The proportions of the remaining components remained unchanged, and the thickness was 0.7 μm. Testing showed that while this sample exhibited some surface energy modulation effect, the lack of nanofillers resulted in insufficient density of the outer layer, significantly reduced scratch resistance and damp heat resistance, and surface fogging and wear marks appeared during long-term use.
[0064] In Examples 1-6, due to the synergistic effect of the interfacial adhesion enhancement layer and the surface energy regulation layer, the pre-coated film exhibits excellent comprehensive performance in terms of adhesion, durability, and surface energy regulation. The interfacial adhesion enhancement layer, through the synergy of polyurethane acrylate, low molecular weight epoxy resin, and silane coupling agent, forms a strong chemical bond between the coating and the BOPET substrate, thereby ensuring the long-term stability of the structure. The surface energy regulation layer, utilizing a composite structure of polyether-type polyurethane and nanofillers, achieves surface energy reduction while also providing scratch resistance, stain resistance, and resistance to damp heat. The two coating layers complement each other, enabling the film of this invention to maintain a good performance balance during subsequent lamination, peeling, and long-term use.
[0065] In contrast, Comparative Examples 1 and 2 omitted the surface energy regulation layer or the interfacial adhesion enhancement layer, respectively, resulting in significant performance limitations in the films. The former, while exhibiting strong adhesion, had excessively high surface energy, while the latter, despite having low surface energy, lacked durability. Comparative Examples 3 and 4, although structurally similar to the examples, failed to achieve ideal interfacial coupling or surface energy control after replacing them with conventional coatings, exhibiting problems such as insufficient adhesion or severe adhesive residue. Comparative Examples 5 and 6 further verified the importance of key components in the formulation; the lack of the silane coupling agent significantly reduced interfacial adhesion, and the absence of nanofillers compromised the density and durability of the surface energy regulation layer. These shortcomings of the comparative examples fully demonstrate the necessity and rationality of the formulation design of this invention.
[0066] By comparing the system of the embodiments with the comparative examples, it can be clearly seen that the interface adhesion enhancement layer and surface energy regulation layer proposed in this invention not only play independent roles, but also produce a synergistic effect through combined design. It is this reasonable combination of structure and formulation that enables the pre-coated film to have strong adhesion, low surface energy and excellent long-term stability, which is significantly better than existing conventional technical solutions.
[0067] Those skilled in the art should understand that although the present invention has been described with reference to multiple embodiments, not every embodiment contains only one independent technical solution. This description is provided merely for clarity; those skilled in the art should understand the specification as a whole and consider the technical solutions involved in each embodiment as being able to be combined with each other to form different embodiments to understand the scope of protection of the present invention.
[0068] The above description is merely an illustrative embodiment of this utility model and is not intended to limit the scope of this utility model. Any equivalent changes, modifications, and combinations made by those skilled in the art without departing from the concept and principles of this utility model should fall within the protection scope of this utility model.
Claims
1. A pre-coated thin film preparation system, characterized in that, The device includes, in sequence, a roll unwinding device, a surface pretreatment device, a first coating machine, a first hot air circulating drying tunnel, a second coating machine, a second hot air circulating drying tunnel, and a cooling winding device. The roll unwinding device is used to carry and continuously unwind the substrate film. The surface pretreatment device is used to perform surface treatment on the unwound substrate surface. The first coating machine is used to uniformly coat an interfacial adhesion enhancement layer on the surface-treated substrate surface, and then the first hot air circulating drying tunnel dries the coated interfacial adhesion enhancement layer. The second coating machine is used to coat a surface energy regulation layer on the outside of the interfacial adhesion enhancement layer, and the second hot air circulating drying tunnel dries the surface energy regulation layer. The cooling winding device is used to cool the coated film and then wind it into a roll.
2. The pre-coated thin film preparation system according to claim 1, characterized in that, It further includes a first coating liquid preparation tank and a second coating liquid preparation tank. The first coating liquid preparation tank is used to mix and prepare the interfacial adhesion enhancement layer coating liquid and transport it to the first coating machine through a pipeline. The second coating liquid preparation tank is used to mix and prepare the surface energy regulation layer coating liquid and transport it to the second coating machine through a pipeline.
3. The pre-coated thin film preparation system according to claim 2, characterized in that, The first coating liquid preparation tank is equipped with a vacuum defoaming device; the second coating liquid preparation tank is equipped with an ultrasonic generator.
4. The pre-coated thin film preparation system according to claim 1, characterized in that, The system further includes a film flipping roller assembly, a third coating machine, a third hot air circulating drying tunnel, a fourth coating machine, and a fourth hot air circulating drying tunnel. The film flipping roller assembly is used to flip the film. The third coating machine and the third hot air circulating drying tunnel are used to coat an interfacial adhesion reinforcement layer on the surface of the flipped film and then dry it. The fourth coating machine and the fourth hot air circulating drying tunnel are used to coat a surface energy regulation layer on the outside of the interfacial adhesion reinforcement layer and then dry it.
5. The pre-coated thin film preparation system according to claim 4, characterized in that, The first coating liquid preparation tank simultaneously supplies coating liquid to the first and third coating machines via pipelines, while the second coating liquid preparation tank simultaneously supplies coating liquid to the second and fourth coating machines via pipelines, thus achieving synchronous supply of coating liquid to both sides.