Insulating layer and composite material

Abstract

This invention relates to an insulating layer and a composite material. The insulating layer includes a base layer and a protective layer. The base layer surface has microstructure protrusions, including first protrusions and second protrusions located between adjacent first protrusions. The protective layer is coated on the side of the base layer with the microstructure protrusions. The protective layer has a thickness of 0.6 μm to 4 μm and includes particles with a particle size of 25 nm to 55 nm. The contact angle α of the protective layer surface is ≥115°. The first and second protrusions provide a stable carrier, ensuring that the overall structure is both anti-fouling and practical. Simultaneously, the reasonable proportion of nanoscale particles in the protective layer balances coating density and surface smoothness, further optimizing the anti-fouling effect in conjunction with the supporting role of the microstructure protrusions. By limiting the thickness of the protective layer, the particle size, and the high contact angle, a low surface energy structure is formed on the surface of the insulating layer, making it difficult for dust and stains to adhere during daily use, and ensuring cleanliness fully meets the requirements for use in electronic products, screen accessories, and other terminal products.

Description

Technical Field

[0001] This invention relates to the field of electronic materials technology, and in particular to an insulating layer and a composite material. Background Technology

[0002] In fields such as electronic devices, screen shading, and electromagnetic shielding components, black insulating layers are commonly used functional substrates, serving the dual functions of insulation, light blocking, and light transmission prevention. Currently, polyester substrates are the mainstream choice for the insulating layer.

[0003] Existing polyester insulation layers have a strong hydrophilic surface, making them highly susceptible to fingerprint and oil stains, resulting in poor fingerprint resistance and failing to meet the cleanliness requirements of high-end electronic products. While applying a hydrophobic coating directly to the polyester substrate to improve fingerprint resistance can lead to poor adhesion between the coating and the substrate, resulting in easy peeling off over long-term use and an inability to consistently achieve fingerprint resistance. Therefore, to address the issues of poor fingerprint resistance in existing insulation layers and insufficient adhesion of hydrophobic coatings, a highly adaptable and stable fingerprint-resistant black insulation layer needs to be developed. Summary of the Invention

[0004] Therefore, it is necessary to provide an insulating layer and a composite material to improve the anti-fingerprint effect.

[0005] The technical solution is as follows: An insulating layer includes a base layer and a protective layer; the surface of the base layer is provided with microstructure protrusions, the microstructure protrusions including a first protrusion and a second protrusion disposed between adjacent first protrusions; the protective layer is coated on the side surface of the base layer where the microstructure protrusions are provided; the thickness of the protective layer is 0.6μm to 4μm, the protective layer includes particles, the particle size is 25nm to 55nm; the surface contact angle α of the protective layer is ≥115°. By limiting the thickness of the protective layer, the particle size and the high contact angle, a low surface energy structure is formed on the surface of the insulating layer, making it difficult for dust and stains to adhere in daily use, and the cleanliness fully meets the usage requirements of electronic products, screen accessories and other terminal products; the reasonable ratio of nanoscale particles in the protective layer takes into account both the density of the coating and the smoothness of the surface, and with the supporting effect of the microstructure protrusions, the anti-fouling effect is further optimized, while providing a stable carrier for the subsequent function of the first and second protrusions, ensuring that the overall structure has both anti-fouling and practicality.

[0006] Specifically, the height of the first protrusion is 2μm to 10μm, the surface roughness Ra is 3μm to 15μm, and the distance between adjacent first protrusions is 20μm to 50μm.

[0007] Specifically, the height of the second protrusion is 0.5 μm to 2 μm, and the surface roughness Ra is 0.5 μm to 3 μm.

[0008] In one embodiment, the first protrusion has a pointed conical structure, and the width of the first protrusion at its 5 / 6 height position is ≤1.5μm; the ratio of the width of the bottom region of the first protrusion to the width at the 5 / 6 height position is 3:1 to 5:1.

[0009] In one embodiment, the second protrusion is a mushroom-shaped structure, and the second protrusion begins to expand radially outward at a position of 1 / 2h of its own height to form an upper cover. The maximum width of the upper cover is greater than the width of the bottom region of the second protrusion. The ratio of the maximum width of the upper cover to the width of the bottom region of the second protrusion is 2:1 to 4:1.

[0010] In one embodiment, the thickness of the protective layer covering the top of the first protrusion is 50nm to 150nm; the thickness of the protective layer covering the top of the second protrusion is 100nm to 300nm; and the ratio of the thickness of the first protrusion top protective layer to the thickness of the second protrusion top protective layer is 1:1.5 to 1:2.5.

[0011] In one embodiment, the protective layer is a nano-silica coating, and the particles are spherical nano-silica particles. Nano-silica itself possesses excellent chemical stability, insulation, and hydrophobic and oleophobic intrinsic properties. As a coating substrate, it does not release harmful substances, and its insulating and protective performance is long-lasting and stable. Combined with the spherical particle morphology, it has good fluidity, uniform dispersion, and no agglomeration. After coating, the coating has extremely high flatness and very few interface defects. This maximizes the hydrophobic and anti-fouling advantages of silica, further enhancing the anti-fingerprint effect, while also reducing the internal stress of the coating and improving its resistance to bending and deformation. At the same time, the nano-silica particles form a film with excellent density, balancing protection and thinness.

[0012] Specifically, the coating density of the protective layer is ≥97%. This ultra-high density prevents leakage through internal pores in the coating, blocking moisture and oil from penetrating and eroding the interface. This ensures stable insulation performance and further enhances the coating's wear resistance and aging resistance, extending the product's service life.

[0013] In one embodiment, the protective layer comprises nano-silica particles and nano-zirconia particles in a mass ratio of 8:2 to 9:1. The silica particles ensure the basic hydrophobic and fingerprint-resistant properties, while the zirconia particles enhance the overall hardness and structural strength of the coating. With precise control of the compounding ratio, the coating retains excellent hydrophobicity while compensating for the insufficient hardness of pure silica coatings, achieving a balance between stain resistance and mechanical properties.

[0014] Specifically, the hardness of the composite coating is 2H to 3H. It is suitable for use in electronic product insulation layers and screen accessories, and is not easily scratched by daily scrapes and touches. It provides dual protection of the coating's appearance integrity and protective performance, solving the problem of soft coatings being easily scratched and affecting usability.

[0015] In one embodiment, the surface energy of the protective layer is ≤20mN / m. This further reduces interfacial adhesion, making it difficult for fingerprints and oil stains to adhere, and also allowing for easy removal of everyday water stains and dust. The surface self-cleaning effect is upgraded, maintaining a clean appearance even after long-term use, making it suitable for end products with high appearance requirements.

[0016] In one embodiment, the surface roughness Ra of the protective layer is 0.05 μm to 0.15 μm. This does not affect the smooth texture of the surface, but further increases the hydrophobic contact angle, enhances the anti-fingerprint effect, and avoids the problem of dirt accumulation caused by excessive roughness.

[0017] In one embodiment, the protective layer has a porous structure with a porosity of 3% to 8%. The porous structure can buffer the internal stress of the coating, improve its resistance to deformation and cracking, without compromising the overall density of the coating, thus balancing insulation and mechanical toughness, and is suitable for bending and deformation scenarios.

[0018] In one embodiment, the base layer is a black PET substrate layer with a thickness of 25μm to 100μm, and the peel strength between the substrate and the transition layer is ≥5N / cm. On the one hand, the black substrate meets the light-shielding and insulation requirements of screens and electronic components, providing strong visual concealment; on the other hand, the strong peel strength between the substrate and the transition layer completely solves the problems of delamination and detachment between the substrate and the transition layer, maximizing the overall bonding stability of the three-layer structure and making it suitable for complex operating environments such as high temperature and high humidity.

[0019] Specifically, carbon black and titanium black are added to the PET material, with a mass ratio of carbon black to titanium black of 3:2. The mass of carbon black and titanium black accounts for 6% to 9% of the total mass of the PET. The two pigments work synergistically to color and block light. Carbon black improves the basic light-blocking properties, while titanium black enhances the uniformity of light blocking and reduces light reflection. A reasonable ratio of the two can maximize the light-blocking effect. At the same time, the addition amount is controlled to avoid insufficient light blocking due to too little addition, or excessive addition causing the PET layer 20 to become brittle and reduce interlayer bonding, thus balancing light-blocking performance and material toughness.

[0020] Furthermore, the carbon black has a particle size of 0.2μm to 0.4μm, and the titanium black has a particle size of 0.3μm to 0.5μm. This particle size range is compatible with the 3:2 mass ratio of the two pigments, ensuring uniform dispersion of the two pigments in the PET raw material, avoiding local pigment agglomeration that forms light-transmitting points, and is also compatible with PET melt extrusion and stretch molding processes without affecting the molding quality of PET, further improving the light-blocking uniformity of PET and enhancing the overall synergistic light-blocking effect.

[0021] In one embodiment, the transition layer is a polyurethane transition layer. Polyurethane material has both adhesion and toughness, and has excellent compatibility with both the PET substrate and the nano-silica coating. It fills the interface gap between the substrate and the protective layer, forming a seamless bonding layer and improving the coating adhesion from the source.

[0022] Specifically, the thickness of the transition layer is 0.12μm to 0.22μm. This avoids insufficient interfacial bonding due to excessive thinness, while also preventing overall coating bulkiness and stress accumulation due to excessive thickness. This ensures that the buffering and bonding effects of the transition layer are maximized, without affecting the overall thinness of the insulation layer.

[0023] A composite material includes an insulating layer, an adhesive layer, a copper foil layer, and a conductive adhesive layer as described above. The adhesive layer is disposed between the insulating layer and the copper foil layer, and the conductive adhesive layer is disposed on the side of the copper foil layer away from the adhesive layer. The side of the conductive adhesive layer away from the copper foil layer is used to adhere and fix it to the screen surface. The insulating layer ensures fingerprint resistance and abrasion resistance, the copper foil layer fulfills the conductivity requirement, the conductive adhesive layer can firmly adhere to the screen surface, and the adhesive layer ensures the stability of the structure of each layer and prevents delamination. The entire composite material is suitable for the integrated use of screen modules and electronic components, combining functionality and practicality, and is easy to install and has stable performance. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the microstructure of the insulating layer described in one embodiment;

[0027] Figure 2 This is a schematic diagram of the microstructure of the protective layer described in one embodiment;

[0028] Figure 3 This is a schematic diagram of the microstructure of the protective layer and the substrate layer described in another embodiment;

[0029] Figure 4 This is a flowchart of an insulating layer preparation method described in one embodiment.

[0030] In the diagram: 10, protective layer; 20, transition layer; 30, base layer; 31, first protrusion; 32, second protrusion. Detailed Implementation

[0031] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0037] like Figure 2 and Figure 3 As shown, in one embodiment of the present invention, the insulating layer includes a base layer 30 and a protective layer 10; the surface of the base layer 30 is provided with microstructure protrusions, the microstructure protrusions include a first protrusion 31 and a second protrusion 32 disposed between adjacent first protrusions 31; the protective layer 10 is coated on the side surface of the base layer 30 where the microstructure protrusions are provided; the thickness of the protective layer 10 is 0.6μm to 4μm, the protective layer 10 includes particles, the particle size is 25nm to 55nm; the surface contact angle α of the protective layer 10 is ≥115°. By limiting the thickness, particle size, and high contact angle of the protective layer 10, a low surface energy structure is formed on the surface of the insulating layer. Dust and stains are not easily adhered during daily use, and the cleanliness fully meets the requirements for use in electronic products, screen accessories, and other terminal products. The reasonable proportion of nano-sized particles in the protective layer 10 balances coating density and surface smoothness. Combined with the supporting effect of the microstructure protrusions, the anti-fouling effect is further optimized. Simultaneously, it provides a stable carrier for the subsequent function of the first and second protrusions 32, ensuring that the overall structure combines anti-fouling properties with practicality. Optionally, the thickness of the protective layer 10 can be 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, 2μm, 3μm, or 4μm. The particle size of the protective layer 10 can be 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, or 55nm.

[0038] It should be noted that, taking the surface of the base layer 30 as the zero point of height, the direction extending perpendicular to the surface of the base layer 30 and toward the first protrusion 31 or the second protrusion 32 is defined as the positive height direction; the vertical distance from the highest point of the first protrusion 31 to the zero point of height is defined as the total height H; the range of the first protrusion 31 from 0 to 1 / 5H in the height direction from the zero point of height is the bottom region, and the range of the first protrusion 31 from 4 / 5H to H in the height direction from the zero point of height is defined as the top region; the vertical distance from the highest point of the second protrusion 32 to the zero point of height is defined as the total height h; the range of the second protrusion 32 from 0 to 1 / 2h in the height direction from the zero point of height is defined as the bottom region, and the range of the second protrusion 32 from 1 / 2h to h in the height direction from the zero point of height is defined as the top region.

[0039] Specifically, the height of the first protrusion 31 is 2μm to 10μm, the surface roughness Ra is 3μm to 15μm, and the spacing between adjacent first protrusions 31 is 20μm to 50μm. This ensures that the protrusion density is moderate, avoiding a rough surface feel due to overly dense arrangement and blind spots due to overly sparse arrangement, while also stably constructing a micro-nano uneven structure, which helps reduce the area for stain adhesion.

[0040] Specifically, the height of the second protrusion 32 is 0.5μm to 2μm, and the surface roughness Ra is 0.5μm to 3μm. The height and roughness parameters of the second protrusion 32 can be staggered and complementary to the first protrusion 31, which not only ensures the uniformity and density of the protective layer 10 coating on the microstructure surface, but also makes it difficult for daily dust and stains to adhere, and the overall cleanliness meets the needs of electronic products and screen accessories.

[0041] like Figure 3 As shown, in one embodiment, the first protrusion 31 has a generally conical structure, and the width of the first protrusion 31 at its 5 / 6 height position is ≤1.5μm; the ratio of the width of the bottom region of the first protrusion 31 to the width at the 5 / 6 height position is 3:1 to 5:1. Thus, the first protrusion 31 can work with the protective layer 10 to achieve excellent anti-fingerprint and anti-fouling performance; even if the surface protective layer 10 wears off due to long-term use, the conical first protrusion 31 remains intact, and its sharp tip has a very small contact area with the finger, thus continuously providing anti-fingerprint protection and preventing loss of anti-fouling function due to wear of the protective layer 10, extending the long-term service life of the insulating layer. At the same time, the conical structure can also help reduce the adhesion of dust and stains, further improving surface cleanliness.

[0042] like Figure 3As shown, in one embodiment, the second protrusion 32 has a mushroom-shaped structure. The second protrusion 32 begins to expand radially outward at a position 1 / 2h of its own height to form an upper cover. The maximum width of the upper cover is greater than the width of the bottom region of the second protrusion 32. The ratio of the maximum width of the upper cover to the width of the bottom region of the second protrusion 32 is 2:1 to 4:1. The upper cover of the second protrusion 32 can physically anchor and interlock with the protective layer 10 coated on its surface, increasing the contact area between the protective layer 10 and the second protrusion 32, effectively preventing the protective layer 10 from peeling or delaminating during repeated wiping and friction. Simultaneously, the second protrusion 32 is positioned between adjacent first protrusions 31, filling the gaps between them, making the protective layer 10 more evenly coated and more tightly adhered, further improving the density of the coating structure, ensuring that the integrity of the coating is not damaged after repeated wiping and friction, that the surface performance is not degraded, and extending the service life of the insulation layer.

[0043] In one embodiment, the thickness of the protective layer 10 covering the top of the first protrusion 31 is 50nm to 150nm; the thickness of the protective layer 10 covering the top of the second protrusion 32 is 100nm to 300nm; and the ratio of the thickness of the protective layer 10 at the top of the first protrusion 31 to the thickness of the protective layer 10 at the top of the second protrusion 32 is 1:1.5 to 1:2.5. By limiting the thickness of the protective layer 10 at the top of the first protrusion 31 and the second protrusion 32 and their proportional relationship, the anti-fingerprint and anti-fouling performance, as well as the coating adhesion and wear resistance, are synergistically improved. The protective layer 10 at the top of the first protrusion 31 is thinner, which avoids the coating being too thick and obscuring its pointed cone structure, ensuring that the pointed top can quickly play its anti-fingerprint role after the protective layer 10 is worn. The protective layer 10 at the top of the second protrusion 32 is thicker, which can match the anchoring requirements of its mushroom-shaped top cover, improve the wear resistance and adhesion of the protective layer 10, and prevent the top cover protective layer 10 from wearing out prematurely. The limited thickness ratio of the two ensures that the thickness distribution of the protective layer 10 on the surface of the insulating layer is reasonable, which not only ensures the anti-fouling and anti-fingerprint effect, but also ensures that the integrity of the coating is not damaged after repeated wiping and friction, and that the surface performance is not degraded. At the same time, it takes into account the cleanliness requirements and is fully adapted to the use needs of terminal products such as electronic products and screen accessories.

[0044] In one embodiment, the protective layer 10 is a nano-silica coating, and the particles are spherical nano-silica particles. Nano-silica itself possesses excellent chemical stability, insulation, and hydrophobic and oleophobic intrinsic properties. As a coating substrate, it does not release harmful substances and has long-lasting and stable insulation and protective performance. Combined with the spherical particle morphology, it has good fluidity, uniform dispersion, and no agglomeration. After coating, the coating has extremely high flatness and very few interface defects. This maximizes the hydrophobic and anti-fouling advantages of silica, further enhancing the anti-fingerprint effect, while also reducing the internal stress of the coating and improving its resistance to bending and deformation. At the same time, the nano-silica particles form a film with excellent density, balancing protection and thinness.

[0045] Specifically, the coating density of the protective layer 10 is ≥97%. This ultra-high density prevents leakage through the internal pores of the coating, blocks water vapor and oil from penetrating and eroding the interface, ensuring stable insulation performance and further improving the coating's wear resistance and aging resistance, thus extending the product's service life.

[0046] In one embodiment, the protective layer 10 comprises nano-silica particles and nano-zirconia particles in a mass ratio of 8:2 to 9:1. That is, the protective layer 10 is a composite coating of nano-silica and nano-zirconia. The silica particles ensure the basic hydrophobic and fingerprint-resistant properties, while the zirconia particles enhance the overall hardness and structural strength of the coating. With precise control of the compounding ratio, the coating retains excellent hydrophobicity while compensating for the insufficient hardness of pure silica coatings, achieving a balance between stain resistance and mechanical properties.

[0047] Specifically, the hardness of the composite coating is 2H to 3H. It is suitable for use in electronic product insulation layers and screen accessories, and is not easily scratched by daily scrapes and touches. It provides dual protection of the coating's appearance integrity and protective performance, solving the problem of soft coatings being easily scratched and affecting usability.

[0048] In one embodiment, the surface energy of the protective layer 10 is ≤20mN / m. This further reduces interfacial adhesion, making it difficult for fingerprints and oil stains to adhere, and also allowing for easy removal of everyday water stains and dust. The surface self-cleaning effect is upgraded, and the product can maintain a clean appearance even after long-term use, making it suitable for end products with high appearance requirements.

[0049] In one embodiment, the surface roughness Ra of the protective layer 10 is 0.05 μm to 0.15 μm. This does not affect the smooth texture of the surface, but further increases the hydrophobic contact angle, enhances the anti-fingerprint effect, and avoids the problem of dirt accumulation caused by excessive roughness; optionally, 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 0.10 μm, 0.11 μm, 0.12 μm, 0.13 μm, 0.14 μm, and 0.15 μm.

[0050] In one embodiment, the protective layer 10 has a porous structure with a porosity of 3% to 8%. The porous structure can buffer the internal stress of the coating, improve its resistance to deformation and cracking, without compromising the overall density of the coating, thus balancing insulation and mechanical toughness, and is suitable for bending and deformation scenarios.

[0051] In one embodiment, the substrate 30 is a black PET substrate layer with a thickness of 25μm to 100μm, and the peel strength between it and the transition layer 20 is ≥5N / cm. On the one hand, the black substrate meets the light-shielding and insulation requirements of screens and electronic components, providing strong visual concealment; on the other hand, the strong peel strength between the substrate and the transition layer 20 completely solves the problem of delamination and detachment between the substrate and the transition layer 20, maximizing the overall bonding stability of the three-layer structure and making it suitable for complex operating environments such as high temperature and high humidity.

[0052] In one embodiment, the transition layer 20 is a polyurethane transition layer 20. Polyurethane material has both adhesion and toughness, and has excellent compatibility with PET substrate and nano-silica coating. It fills the interface gap between the substrate and the protective layer 10 to form a seamless bonding layer, thereby improving the coating adhesion from the source.

[0053] Specifically, the thickness of the transition layer 20 is 0.12μm to 0.22μm. This avoids insufficient interfacial bonding due to excessive thinness, while also preventing overall coating bulkiness and stress accumulation due to excessive thickness. This ensures that the buffering and bonding effects of the transition layer 20 are maximized, without affecting the overall thinness of the insulating layer.

[0054] Optionally, the thickness of the transition layer 20 can be 0.12μm, 0.13μm, 0.14μm, 0.15μm, 0.16μm, 0.17μm, 0.18μm, 0.19μm, 0.20μm, 0.21μm, or 0.22μm.

[0055] A composite material includes an insulating layer, an adhesive layer, a copper foil layer, and a conductive adhesive layer as described above. The adhesive layer is disposed between the insulating layer and the copper foil layer, and the conductive adhesive layer is disposed on the side of the copper foil layer away from the adhesive layer. The side of the conductive adhesive layer away from the copper foil layer is used to adhere and fix it to the screen surface. The insulating layer ensures fingerprint resistance and abrasion resistance, the copper foil layer fulfills the conductivity requirement, the conductive adhesive layer can firmly adhere to the screen surface, and the adhesive layer ensures the stability of the structure of each layer and prevents delamination. The entire composite material is suitable for the integrated use of screen modules and electronic components, combining functionality and practicality, and is easy to install and has stable performance.

[0056] A method for preparing an insulating layer, comprising the steps described above:

[0057] (1) The surface of the substrate to be coated is pretreated to obtain a clean substrate 30;

[0058] (2) Prepare the coating liquid for the transition layer 20, and coat it evenly on the surface of the pretreated base layer 30. After shaping treatment, the transition layer 20 is formed.

[0059] (3) Prepare the precursor of the protective layer 10, adjust the dispersion state of the particles in the precursor, and coat it evenly on the side of the transition layer 20 away from the base layer 30. After film formation treatment, the initial protective layer 10 is formed.

[0060] (4) The protective layer 10 is cured and post-treated to achieve the preset thickness and surface properties, thereby obtaining the insulating layer.

[0061] The precise preparation of the insulation layer is achieved through a step-by-step process of substrate pretreatment, coating of transition layer 20, dispersion of precursor of protective layer 10, and post-curing treatment: substrate pretreatment eliminates surface impurities and ensures interface cleanliness; step-by-step coating avoids mutual interference between multiple materials, and the formation of transition layer 20 and protective layer 10 is uniform and controllable; particle dispersion control and post-curing treatment ensure that parameters such as coating thickness, particle size, and contact angle are accurately met. The process has strong repeatability, high yield, and stable performance of the obtained insulation layer, which is suitable for industrial mass production.

[0062] Specifically, in step (1), the black PET substrate is first ultrasonically cleaned with a mixture of anhydrous ethanol and deionized water at a frequency of 28kHz to 40kHz for 5 to 10 minutes to remove oil, dust, and electrostatically adsorbed impurities from the substrate surface. Then, a low-temperature plasma surface activation treatment is performed at a plasma power of 80W to 120W for 30 to 60 seconds. Finally, hot air drying is carried out at a temperature of 60℃ to 80℃ for 3 to 5 minutes to completely remove residual moisture, resulting in a clean and activated substrate layer 30. It should be noted that the volume ratio of the anhydrous ethanol to deionized water mixture is 7:3.

[0063] This thoroughly removes impurities and weak boundary layers from the substrate surface, avoiding pinholes and bulges in the coating caused by impurities; plasma activation can increase the surface energy of the substrate, enhance the wettability and adhesion between the subsequent transition layer 20 and the substrate, and eliminate delamination and debonding problems; low-temperature drying prevents the PET substrate from deforming due to heat and ensures the flatness of the substrate.

[0064] Furthermore, the low-temperature plasma surface activation treatment uses a mixture of argon and oxygen gas with a volume ratio of 9:1.

[0065] Specifically, in step (2), a polyurethane coating solution is prepared, using aliphatic polyurethane resin as the main component, and mixed with ethyl acetate and butanone as solvents in a mass ratio of 6:4. The solid content of the coating solution is controlled to be 15%–20%, and the viscosity is 200 mPa·s–300 mPa·s. The coating is performed using a microgravure coating method, with a coating speed of 5 m / min–10 m / min and a coating pressure of 0.2 MPa–0.4 MPa to ensure coating uniformity. Then, the solution is placed in a setting oven and set using gradient hot air. First, a low-temperature setting is performed at 50°C–60°C for 1 min–2 min to remove most of the solvent. Then, a medium-temperature setting is performed at 70°C–80°C for 2 min–3 min to form a continuous and uniform polyurethane transition layer 20 with a thickness of 0.12 μm–0.22 μm.

[0066] This allows for precise control of coating liquid parameters and coating process, avoiding sagging and uneven thickness of the transition layer 20; the gradient shaping process prevents pinholes and cracks caused by rapid solvent evaporation, ensuring that the transition layer 20 is dense and continuous; the polyurethane transition layer 20 fully wets the substrate surface, building a bonding bridge between the substrate and the protective layer 10, thereby improving the overall adhesion from the source.

[0067] Specifically, in step (3), a precursor for the protective layer 10, consisting of nano-silica (or a compound), is prepared. The precursor is spherical nano-silica of 25nm–55nm as the main material, with a small amount of dispersant, specifically ammonium polyacrylate, added at 0.5%–1%, and supplemented with film-forming aids. An ultrasonic-high-speed shearing combined dispersion process is employed, with an ultrasonic frequency of 40kHz, a shearing speed of 3000r / min–5000r / min, and a dispersion time of 20min–30min, to thoroughly break up particle agglomeration and form a uniform and stable dispersion. This dispersion is then coated onto the surface of the transition layer 20 using slit coating or spray coating at a speed of 3m / min–8m / min, with the wet film thickness controlled at 1.0μm–1.8μm. After leveling treatment at a temperature of 40℃–50℃ for 1min–2min, the initial protective layer 10 is formed.

[0068] This combined dispersion process ensures uniform dispersion of nanoparticles, preventing agglomeration that could lead to coating protrusions and excessive roughness; precise temperature control and leveling allow for full spread of the precursor, ensuring uniform coating thickness; and the wet film thickness allows for evaporation space, ensuring that the final dry film thickness remains stable at 0.6–1.2 μm, meeting parameter requirements.

[0069] Specifically, in step (4), a segmented curing process is adopted. First, low-temperature pre-curing is carried out at a temperature of 80℃~90℃ for 5min~8min to allow the coating to initially cross-link and form. Then, high-temperature curing is carried out at a temperature of 110℃~130℃ for 10min~15min to achieve complete cross-linking and curing. After curing, plasma polishing is performed at a power of 50W~80W for 20s~40s to adjust the surface roughness Ra of the coating to 0.05μm~0.15μm and improve the surface density. Finally, the coating is cooled to room temperature and the contact angle, density, hardness and other indicators of the coating are tested. After meeting the standards, the finished insulation layer is obtained.

[0070] Segmented curing eliminates internal stress in the coating, avoiding cracking and warping caused by curing shrinkage, and improving abrasion resistance and bending resistance; post-processing precisely controls surface morphology and performance, ensuring a surface contact angle ≥115° and density ≥97%, and enhancing anti-fingerprint, hydrophobic and oleophobic effects; the entire process is controllable, with high performance consistency, and is suitable for mass production.

[0071] The insulating layer provided by the present invention will be described below with reference to specific embodiments.

[0072] Example 1

[0073] The base layer 30 is a black PET substrate; the transition layer 20 is made of polyurethane with a thickness of 0.12μm; the protective layer 10 has a thickness of 0.6μm, a particle size of 25nm, and a surface contact angle of 116°.

[0074] Preparation steps

[0075] (1) The surface of the black PET substrate to be coated is pretreated to obtain a clean base layer 30;

[0076] (2) Prepare a polyurethane transition layer 20 coating liquid, and coat it evenly on the surface of the pretreated base layer 30. After shaping treatment, a transition layer 20 with a thickness of 0.12μm is formed.

[0077] (3) Prepare the precursor of the protective layer 10, regulate the dispersion state of the 25nm particles in the precursor, and uniformly coat it on the side of the transition layer 20 away from the base layer 30. After film formation treatment, the initial protective layer 10 is formed.

[0078] (4) The initial protective layer 10 is cured and post-treated to achieve a thickness of 0.6 μm and preset surface properties, thus obtaining the finished insulation layer.

[0079] The surface contact angle meets the standard, the coating adhesion is excellent, and there is no peeling or flaking; the anti-fingerprint effect is qualified, stains are easy to wipe, and the wipe resistance meets the usage requirements.

[0080] Example 2

[0081] The base layer 30 is a black PET substrate; the transition layer 20 is made of polyurethane with a thickness of 0.17μm; the protective layer 10 has a thickness of 0.9μm, a particle size of 40nm, and a surface contact angle of 119°.

[0082] Preparation steps

[0083] (1) The surface of the black PET substrate to be coated is pretreated to obtain a clean base layer 30;

[0084] (2) Prepare a polyurethane transition layer 20 coating liquid, and coat it evenly on the surface of the pretreated base layer 30. After shaping treatment, a transition layer 20 with a thickness of 0.17μm is formed.

[0085] (3) Prepare the precursor of the protective layer 10, regulate the dispersion state of the 40nm particles in the precursor, and coat it evenly on the side of the transition layer 20 away from the base layer 30. After film formation treatment, the initial protective layer 10 is formed.

[0086] (4) The initial protective layer 10 is cured and post-treated to achieve a thickness of 0.9 μm and preset surface properties, thus obtaining the finished insulation layer.

[0087] It has excellent surface contact angle, extremely strong coating adhesion, and no delamination defects; it has excellent anti-fingerprint effect, zero fingerprint residue, meets the standard number of wipes, and has excellent surface cleanliness.

[0088] Example 3

[0089] The base layer 30 is a black PET substrate; the transition layer 20 is made of polyurethane with a thickness of 0.22μm; the protective layer 10 has a thickness of 1.2μm, a particle size of 55nm, and a surface contact angle of 122°.

[0090] Preparation steps

[0091] (1) The surface of the black PET substrate to be coated is pretreated to obtain a clean base layer 30;

[0092] (2) Prepare a polyurethane transition layer 20 coating liquid, and coat it evenly on the surface of the pretreated base layer 30. After shaping treatment, a transition layer 20 with a thickness of 0.22 μm is formed.

[0093] (3) Prepare the precursor of the protective layer 10, regulate the dispersion state of the 55nm particles in the precursor, and coat it evenly on the side of the transition layer 20 away from the base layer 30. After film formation treatment, the initial protective layer 10 is formed.

[0094] (4) The initial protective layer 10 is cured and post-treated to achieve a thickness of 1.2μm and preset surface properties, thus obtaining the finished insulation layer.

[0095] The surface contact angle meets the standard, the coating structure is dense, and the adhesion is stable; it has good anti-fingerprint effect, excellent wear resistance and wipe resistance, and its performance does not degrade over long-term use.

[0096] Example 4

[0097] The base layer 30 is a black PET substrate; the transition layer 20 is made of polyurethane with a thickness of 0.15μm; the protective layer 10 has a thickness of 0.8μm, a particle size of 30nm, and a surface contact angle of 118°.

[0098] Preparation steps

[0099] (1) The surface of the black PET substrate to be coated is pretreated to obtain a clean base layer 30;

[0100] (2) Prepare a polyurethane transition layer 20 coating liquid, and coat it evenly on the surface of the pretreated base layer 30. After shaping treatment, a transition layer 20 with a thickness of 0.15μm is formed.

[0101] (3) Prepare the precursor of the protective layer 10, regulate the dispersion state of the 30nm particles in the precursor, and coat it evenly on the side of the transition layer 20 away from the base layer 30. After film formation treatment, the initial protective layer 10 is formed.

[0102] (4) The initial protective layer 10 is cured and post-treated to achieve a thickness of 0.8 μm and preset surface properties, thus obtaining the finished insulation layer.

[0103] The surface contact angle is qualified, the coating adhesion is excellent, and there are no problems with bulging or cracking; the anti-fingerprint effect is good, the surface is easy to clean, and the wipe resistance meets the product standards.

[0104] Example 5

[0105] The base layer 30 is a black PET substrate; the transition layer 20 is made of polyurethane with a thickness of 0.20μm; the protective layer 10 has a thickness of 1.0μm, a particle size of 50nm, and a surface contact angle of 120°.

[0106] Preparation steps

[0107] (1) The surface of the black PET substrate to be coated is pretreated to obtain a clean base layer 30;

[0108] (2) Prepare a polyurethane transition layer 20 coating liquid, and coat it evenly on the surface of the pretreated base layer 30. After shaping treatment, a transition layer 20 with a thickness of 0.20 μm is formed.

[0109] (3) Prepare the precursor of the protective layer 10, regulate the dispersion state of the 50nm particles in the precursor, and uniformly coat it on the side of the transition layer 20 away from the base layer 30. After film formation treatment, the initial protective layer 10 is formed.

[0110] (4) The initial protective layer 10 is cured and post-treated to achieve a thickness of 1.0 μm and preset surface properties, thus obtaining the finished insulation layer.

[0111] It has an excellent surface contact angle, a strong coating bond, and no risk of delamination; it has outstanding anti-fingerprint, hydrophobic and oleophobic effects, excellent wipe resistance, and its surface cleanliness meets the standard for a long time.

[0112] Comparative Example 1

[0113] The base layer 30 is a black PET substrate; no polyurethane transition layer 20 is provided; the protective layer 10 has a thickness of 0.9μm, a particle size of 40nm, and a surface contact angle of 119°.

[0114] Preparation steps

[0115] (1) The surface of the black PET substrate to be coated is pretreated to obtain a clean base layer 30;

[0116] (2) The preparation steps of polyurethane transition layer 20 are omitted;

[0117] (3) Prepare the precursor of the protective layer 10, regulate the dispersion state of the 40nm particles in the precursor, and directly and uniformly coat it on the surface of the pretreated substrate layer 30. After film formation treatment, the initial protective layer 10 is formed.

[0118] (4) The initial protective layer 10 is cured and post-treated to achieve a thickness of 0.9 μm, thus obtaining an insulating layer. The coating has extremely poor adhesion, resulting in peeling and flaking. Although the contact angle meets the standard, the coating is easily damaged and its abrasion resistance is unqualified, failing to meet the usage requirements.

[0119] Comparative Example 2

[0120] The base layer 30 is a black PET substrate; the transition layer 20 is made of polyurethane with a thickness of 0.17μm; the protective layer 10 has a thickness of 0.5μm, a particle size of 20nm, and a surface contact angle of 110°.

[0121] Preparation steps

[0122] (1) The surface of the black PET substrate to be coated is pretreated to obtain a clean base layer 30;

[0123] (2) Prepare a polyurethane transition layer 20 coating liquid, and coat it evenly on the surface of the pretreated base layer 30. After shaping treatment, a transition layer 20 with a thickness of 0.17μm is formed.

[0124] (3) Prepare the precursor of the protective layer 10, regulate the dispersion state of the 20nm particles in the precursor, and coat it evenly on the side of the transition layer 20 away from the base layer 30. After film formation treatment, the initial protective layer 10 is formed.

[0125] (4) The initial protective layer 10 is cured and post-treated to achieve a thickness of 0.5μm, thus obtaining an insulating layer. The surface contact angle is substandard, the anti-fingerprint effect is extremely poor, and fingerprint residue is obvious and difficult to wipe off; the coating thickness and particle size exceed the standard, the structure is loose, and the adhesion and wiping resistance do not meet the product requirements.

[0126] In summary, the five embodiments, through the synergistic cooperation of the black PET base layer 30, the polyurethane transition layer 20, and the nano-protective layer 10, all achieved the core technical effects of effectively improving anti-fingerprint effect, significantly enhancing coating adhesion, ensuring surface cleanliness meets product usage requirements, and providing excellent wipe resistance. Only due to the gradient differences in the thickness of the transition layer 20, the protective layer 10, and the particle size, the various performance characteristics showed slight fluctuations, all of which met the actual usage requirements of the product. In contrast, the two comparative embodiments, lacking the core structure or core parameter limitations of this invention, resulted in a significant decrease in coating adhesion, anti-fingerprint effect, and wipe resistance, and the surface cleanliness failed to meet the product usage standards. This fully demonstrates the inventiveness and practicality of the technical solution of this invention.

[0127] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0128] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An insulating layer, characterized in that, The substrate includes a base layer and a protective layer. The surface of the base layer is provided with microstructure protrusions, the microstructure protrusions including first protrusions and second protrusions disposed between adjacent first protrusions. The protective layer is coated on the side surface of the base layer where the microstructure protrusions are provided. The thickness of the protective layer is 0.6μm to 4μm, the protective layer includes particles with a particle size of 25nm to 55nm, and the surface contact angle α of the protective layer is ≥115°.

2. The insulating layer according to claim 1, characterized in that, The height of the first protrusion is 2μm to 10μm, the surface roughness Ra is 3μm to 15μm, and the spacing between adjacent first protrusions is 20μm to 50μm; and / or The height of the second protrusion is 0.5μm to 2μm, and the surface roughness Ra is 0.5μm to 3μm.

3. The insulating layer according to claim 1, characterized in that, The first protrusion has a pointed conical structure, and the width of the first protrusion at its 5 / 6 height position is ≤1.5μm; the ratio of the width of the bottom region of the first protrusion to the width at the 5 / 6 height position is 3:1 to 5:

1.

4. The insulating layer according to claim 1, characterized in that, The second protrusion has a mushroom-shaped structure. The second protrusion begins to expand radially outward at a position 1 / 2h of its own height to form an upper cover. The maximum width of the upper cover is greater than the width of the bottom area of ​​the second protrusion. The ratio of the maximum width of the upper cover to the width of the bottom area of ​​the second protrusion is 2:1 to 4:

1.

5. The insulating layer according to claim 1, characterized in that, The thickness of the protective layer covering the top of the first protrusion is 50nm to 150nm; the thickness of the protective layer covering the top of the second protrusion is 100nm to 300nm; and the ratio of the thickness of the protective layer at the top of the first protrusion to the thickness of the protective layer at the top of the second protrusion is 1:1.5 to 1:2.

5.

6. The insulating layer according to claim 1, characterized in that, The protective coating is a nano-silica coating, and the particles are spherical nano-silica particles; and / or The coating density of the protective coating is ≥97%.

7. The insulating layer according to claim 1, characterized in that, The protective layer is a composite coating consisting of nano-silica particles and nano-zirconia particles, with a mass ratio of 8:2 to 9:

1.

8. The insulating layer according to claim 6, characterized in that, The hardness of the composite coating is 2H to 3H; and / or The surface roughness Ra of the protective layer is 0.05 μm to 0.15 μm; and / or The protective layer has a porous structure with a porosity of 3% to 8%; and / or The surface energy of the protective layer is ≤20mN / m.

9. The insulating layer according to any one of claims 1-8, characterized in that, The insulating layer further includes a transition layer disposed between the base layer and the protective layer; the transition layer is a polyurethane transition layer; and / or The thickness of the transition layer is 0.12 μm to 0.22 μm; and / or The base layer is a black PET substrate layer with a thickness of 25μm to 100μm, and the peel strength with the transition layer is ≥5N / cm.

10. A composite material, characterized in that, It includes an insulating layer, an adhesive layer, a copper foil layer, and a conductive adhesive layer as described in any one of claims 1-9; the adhesive layer is disposed between the insulating layer and the copper foil layer, and the conductive adhesive layer is disposed on the side of the copper foil layer away from the adhesive layer, the side of the conductive adhesive layer away from the copper foil layer being used to adhere and fix it to the screen surface.

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