Oca substrate touch screen and method for manufacturing the same

Abstract

The application discloses an OCA substrate touch screen and a preparation method thereof, which comprises a substrate, a protective layer and a base connected in sequence, the protective layer is arranged on the side of the substrate with a touch sensor, and the protective layer comprises a protective layer, a heat conduction layer and a heat radiation layer connected in sequence; the protective layer is a PI-Si dense layer, the heat conduction layer is an h-BN / SiC-NWs / PI-Si composite fiber network layer, and the heat radiation layer is a photonic crystal microsphere close-packed layer. The protective film layer arranged in the application can effectively protect the touch sensor. When the OCA substrate touch screen is installed, the protective film layer can avoid damage to the touch sensor by cooperating with the PI-Si dense layer, the h-BN / SiC-NWs / PI-Si composite fiber network layer and the photonic crystal microsphere close-packed layer. The dense structure of the PI-Si dense layer can effectively block the penetration of moisture and oxygen, the h-BN / SiC-NWs / PI-Si composite fiber network layer has a pore structure and can effectively absorb mechanical impact capacity, and the hard surface structure of the photonic crystal microsphere close-packed layer can also resist external force impact, so that the protection of the touch sensor is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of display manufacturing methods, in particular to an OCA substrate touch screen and a preparation method thereof. BACKGROUND

[0002] The OCA substrate touch screen is a touch screen technology that uses optical transparent adhesive (OCA) as the bonding material, commonly used in smart devices, which provides high light transmittance and excellent visual effects by closely combining the touch screen and the display, and the connection between the OCA substrate touch screen and the display is usually achieved by directly bonding the touch screen layer to the surface of the display.

[0003] In large-scale production and assembly, a frame is used to connect the OCA substrate touch screen and the display, and the OCA substrate touch screen is fixed by the frame and is not directly bonded to the surface of the display, and the OCA substrate touch screen can be hung above the display through the frame to ensure a certain gap between the two, and the electronic components on the OCA substrate touch screen are at the back of the touch screen to avoid contact between the electronic components and the display, but the electronic components on the OCA substrate touch screen are easily affected by external pressure, scratching or mechanical stress during the assembly process, which may cause damage to the electronic components on the OCA substrate touch screen.

[0004] Currently, when the OCA substrate touch screen and the display are connected by the frame, the OCA substrate on the OCA substrate touch screen can protect the electronic components during the assembly process, but since the OCA substrate touch screen and the display are connected by the frame, a gap is formed between the OCA substrate and the display, and this physical isolation reduces the direct protection effect of the OCA substrate on the electronic components, and the electronic components are exposed to the external environment, which is more easily affected by the external environment, thereby increasing the risk of damage.

[0005] Therefore, the present application provides an OCA substrate touch screen and a preparation method thereof to solve the above-mentioned problem of reduced protection effect of the OCA substrate. SUMMARY

[0006] The present application aims to provide an OCA substrate touch screen and a preparation method thereof, which solves the problem of reduced protection effect of the OCA substrate.

[0007] To achieve this purpose, the present application adopts the following technical solutions:

[0008] An OCA substrate touch screen, comprising a substrate, a protective layer and a substrate connected in sequence, the protective layer is arranged on the side of the substrate with a touch sensor, and the protective layer comprises a protective layer, a heat-conducting layer and a heat-radiation layer connected in sequence.

[0009] The protective layer is a PI-Si dense layer, the heat-conducting layer is a h-BN / SiC-NWs / PI-Si composite fiber network layer, and the heat radiation layer is a photonic crystal microsphere close-packed layer.

[0010] The thickness of the protective layer is 2 μm, the thickness of the heat-conducting layer is 15 μm, and the thickness of the heat radiation layer is 3 μm.

[0011] A preparation method of an OCA substrate touch screen, applied to the OCA substrate touch screen as described above, and comprising the following steps:

[0012] Step S1, providing a substrate with a coated surface corresponding to a touch sensor on one side;

[0013] Step S2, preparing a molding solution from PI-Si, h-BN, SiC-NWs, silica@Ag, and an epoxy silane crosslinking agent;

[0014] Step S3, coating the molding solution on the coated area of the substrate by a magnetic suspension spraying device;

[0015] Step S4, performing stepwise thermal curing on the molding solution in the coated area to form a protective film layer with a PI-Si dense layer, a h-BN / SiC-NWs / PI-Si composite fiber network layer, and a photonic crystal microsphere close-packed layer;

[0016] Step S5, coating an optical transparent adhesive on the protective film layer, and forming a substrate after curing to obtain an OCA substrate touch screen.

[0017] The step S2 specifically comprises:

[0018] Step S21, dissolving PI-Si in NMP for stirring to obtain a first solution;

[0019] Step S22, pretreating h-BN, SiC-NWs, and silica@Ag;

[0020] Step S23, adding the pretreated h-BN, SiC-NWs, and silica@Ag into the first solution for ultrasonic dispersion to obtain a second solution;

[0021] Step S24, stirring the crosslinking agent in the second solution to obtain a molding solution.

[0022] In the step S21, the stirring speed is 700-900 rpm, the stirring temperature is 40-60℃, and the stirring time is 1.5-2.5 h;

[0023] The step S22 is pre-treating h-BN in a vacuum drying environment at 50-70 DEG C for 3-5h, pre-treating SiC-NWs using 3-8% concentration of hydrofluoric acid etching for 3-7min, and pre-treating silica@Ag in an ethanol mixture for 10-20min of ultrasonic dispersion;

[0024] In the step S23, the power of ultrasonic dispersion is 250-350W, and the time is 1.5-3h.

[0025] In the step S24, the mass ratio of PI-Si, h-BN, SiC-NWs, silica@Ag and crosslinking agent in the forming solution is (55-65):(20-30):(8-12):(3-5):(0.8-1.2), the stirring time is 10-15min, and the stirring speed is 200-400rpm.

[0026] The forming solution is injected into a magnetic suspension spraying device, and the magnetic field generated by the magnetic suspension spraying device is perpendicular to the coating area. Then the magnetic suspension spraying device carries a spray head through a multi-axis mechanical arm, and sprays the forming solution on the coating area by nitrogen driving. At the same time, the forming solution is also electrostatically atomized to form droplets when it is sprayed out of the spray head, and is deposited on the coating area under the action of the magnetic field.

[0027] The magnetic field strength is 0.3-0.7T, the spraying pressure is 0.2-0.5MPa, the spraying speed is 15-30mm / s, and the spraying interval is 10-20cm.

[0028] The step S4 specifically comprises:

[0029] The step S41 is hot air curing of the forming solution at 70-90 DEG C for 20-40min.

[0030] The step S42 is infrared radiation curing of the forming solution treated in the step S41 at 110-130 DEG C for 0.5-2h.

[0031] The step S43 is laser scanning curing of the forming solution treated in the step S42 at 140-160 DEG C for 5-15min, to obtain a protective film layer.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] 1. The OCA substrate touch screen and its preparation method, the protective film layer can effectively protect the touch sensor, the protective film layer can improve the protection effect of the touch sensor during the installation of the OCA substrate touch screen, so as to avoid the damage of the touch sensor, the dense structure of the PI-Si dense layer can effectively block the penetration of moisture and oxygen, the h-BN / SiC-NWs / PI-Si composite fiber network layer has a pore structure and can effectively absorb mechanical impact, and the hard surface structure of the photonic crystal microsphere close-packed layer can resist external force impact, so as to realize the protection of the touch sensor.

[0034] 2. The OCA substrate touch screen and its preparation method, the h-BN and SiC-NWs in the h-BN / SiC-NWs / PI-Si composite fiber network layer can be arranged in a direction to form an efficient heat conduction path, the heat conduction performance of the protective film layer is significantly enhanced, the heat generated by the substrate and the touch sensor can be effectively conducted out, and the heat is emitted in the form of infrared through black body radiation by cooperating with the photonic crystal microsphere close-packed layer, so as to avoid heat accumulation, and the heat dissipation efficiency of the substrate and the touch sensor is improved.

[0035] 3. The OCA substrate touch screen and its preparation method, the forming solution is coated by the magnetic suspension spraying equipment, the high-precision camera and the multi-axis mechanical arm are cooperated, the uniform deposition of the forming solution on the coating surface can be ensured, the uneven coating problem in the traditional coating mode can be avoided, the forming solution droplets in the spraying process are subjected to directional force under the synergistic control of the magnetic field and the electric field, the uniformity and stability of the protective film layer are ensured, in addition, the electrostatic atomization technology can effectively reduce the droplet size and further improve the coating quality.

[0036] 4. The OCA substrate touch screen and its preparation method, the hydrogen bond and the silane coupling agent of the PI-Si dense layer in the protective film layer and the substrate coating surface are combined, the adhesion of the protective film layer is enhanced, the separation of the protective film layer and the substrate is avoided, and the connection effect of the protective film layer and the substrate is improved, in addition, the PI-Si dense layer has excellent moisture resistance, can effectively prevent moisture penetration, so as to protect the touch sensor from oxidation damage and prolong the service life of the equipment.

[0037] 5、The OCA substrate touch screen and the preparation method thereof, through the PI-Si dense layer and the h-BN / SiC-NWs / PI-Si composite fiber network layer structure in the protective film layer, the protective film layer has high elongation at break and flexibility, can adapt to the bending deformation of the substrate, such flexibility not only performs well in the application scene such as the curved screen, but also can absorb the impact force when the substrate is subjected to external force impact, and damage is avoided. The substrate can adapt to a wider application environment, and a more stable and durable use experience is provided. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0039] The structures, proportions, sizes, etc. shown in the drawings of the present specification are only used to cooperate with the content disclosed in the specification, so that those skilled in the art can understand and read, and are not used to limit the limiting conditions that the present application can be implemented. Therefore, any modification of structure, change of proportion relationship or adjustment of size, which does not affect the effects and purposes that the present application can produce, should still fall within the scope of the technical content disclosed by the present application.

[0040] Figure 1 It is a sectional view of the protective film layer in the present application.

[0041] Figure 2 It is a flow chart of the preparation method of the OCA substrate touch screen in the present application.

[0042] Illustration: 1, substrate; 2, protective layer; 21, protective layer; 22, heat conducting layer; 23, heat radiation layer; 3, substrate; 4, touch sensor. DETAILED DESCRIPTION

[0043] In order to make the invention purpose, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the embodiments described below are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of the present application.

[0044] In the description of the present application, it should be understood that the terms "upper", "lower", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there can be a component disposed therebetween.

[0045] Embodiment 1:

[0046] Please refer to Figure 1 The OCA substrate touch screen in the embodiment includes a substrate 11, a protective layer 2 and a substrate 3 connected in sequence, the protective layer 2 is arranged on the side of the substrate 11 having a touch sensor 4, and the protective layer 2 includes a protective layer 21, a heat conduction layer 22 and a heat radiation layer 23 connected in sequence.

[0047] The protective layer 21 is a PI-Si dense layer, the heat conduction layer 22 is an h-BN / SiC-NWs / PI-Si composite fiber network layer, and the heat radiation layer 23 is a photonic crystal microsphere close-packed layer.

[0048] Specifically, the touch sensor 4 is a resistive sensor, that is, an electronic component in the OCA substrate touch screen at the back of the touch screen, and the electronic component includes but is not limited to the touch sensor 4.

[0049] Further, the thickness of the protective layer 21 is 2 μm, the thickness of the heat conduction layer 22 is 15 μm, and the thickness of the heat radiation layer 23 is 3 μm.

[0050] It can be known that the dense structure of the PI-Si dense layer can effectively block the penetration of wet oxygen to protect the substrate 1 and the touch sensor 4, and the PI-Si dense layer and the coating surface of the substrate 1 are combined by hydrogen bonds and silane coupling agents to improve the peeling strength, so that the protective film layer is more firm when connected with the substrate 1. In addition, the PI-Si in the PI-Si dense layer also endows the h-BN / SiC-NWs / PI-Si composite fiber network layer with a 50% elongation at break, so that the h-BN / SiC-NWs / PI-Si composite fiber network layer can adapt to the bending deformation of the substrate 1, thereby realizing flexible support. The h-BN / SiC-NWs / PI-Si composite fiber network layer has a porous structure, which can effectively absorb mechanical impact capacity to protect the substrate 1 and the touch sensor 4. At the same time, the continuous heat conduction path formed by the directional arrangement of h-BN in the h-BN / SiC-NWs / PI-Si composite fiber network layer can effectively conduct heat out, avoiding the heat generated by the substrate 1 and the touch sensor 4 after the protective film layer is set. The heat cannot be dissipated in time, and the SiC-NWs combined with h-BN by van der Waals force can also reduce the interfacial thermal resistance, thereby further improving the heat conduction efficiency. When the heat is transmitted out of the h-BN / SiC-NWs / PI-Si composite fiber network layer, the photonic crystal microsphere close-packed layer radiates heat in the form of infrared through blackbody radiation to avoid heat accumulation. At the same time, the hard surface structure formed by the close-packed microspheres on the surface of the photonic crystal microsphere close-packed layer can also resist external force impact to avoid damage to the substrate 1 and the touch sensor 4 due to scratching or extrusion.

[0051] Specifically, after the protective film layer is set on the substrate 1, the heat generated by the touch sensor 4 is first rapidly conducted to the h-BN / SiC-NWs / PI-Si composite fiber network layer through the PI-Si dense layer, and then diffused to the edge region along the in-plane by the directional network of h-BN in the layer. SiC nanowires enhance lateral heat transfer and reduce local hot spots. Finally, the photonic crystal microsphere close-packed layer radiates heat to the environment through radiation, thereby realizing heat dissipation of the touch sensor 4. In addition, the protective film layer can block wet oxygen through the PI-Si dense layer to prevent the touch sensor 4 from being oxidized. The hard surface structure of the photonic crystal microsphere close-packed layer can resist scratching when the substrate 1 and the touch sensor 4 are subjected to mechanical impact, thereby improving the service life of the substrate 1 and the touch sensor 4. At the same time, the h-BN / SiC-NWs / PI-Si composite fiber network layer can also absorb mechanical impact to further protect the substrate 1 and the touch sensor 4.

[0052] It needs to be emphasized that PI-Si is included in the PI-Si dense layer, PI-Si has high optical transparency, and the thickness is only 2 μm, and the absorption of the visible light band can be ignored; h-BN, SiC-NWs, PI-Si are included in the h-BN / SiC-NWs / PI-Si composite fiber network layer, h-BN is a wide band gap insulator, and the light transmission is excellent, SiC-NWs can significantly reduce light scattering, and the light transmittance can still be kept > 85% at 15 μm thickness; the photonic crystal microsphere close-packed layer includes silica@Ag, the photonic crystal microsphere close-packed layer controls the infrared radiation through the photonic crystal structure, and the scattering of visible light can be controlled at a low level through the close-packed structure and its thickness, so when the protective layer 2 composed of the PI-Si dense layer, the h-BN / SiC-NWs / PI-Si composite fiber network layer, and the photonic crystal microsphere close-packed layer is arranged on the substrate 1 and the base, the use requirements of the OCA base touch screen can be met.

[0053] Embodiment 2:

[0054] Please refer to Figure 2 The preparation method of the OCA base touch screen in the embodiment is applied to the OCA base touch screen as in Embodiment 1, and the integration process includes the following steps:

[0055] Step S1, providing a substrate 1 with a coated surface corresponding to a touch sensor 4 on one side;

[0056] It needs to be noted that the coated surface of the substrate 1 is pretreated by using argon plasma cleaning power of 50 W for 1 min, so as to improve the surface energy of the coated surface, and the surface energy is increased to more than 50 mN / m; by pretreating the coated surface of the substrate 1, active groups -OH and -COOH can be produced on the coated surface, so as to improve the adhesion of the subsequent film layer during coating.

[0057] Step S2, preparing a molding solution by using PI-Si polyimide-siloxane copolymer, h-BN hexagonal boron nitride nanosheet, SiC-NWs silicon carbide nanowire, silica@Ag photonic crystal microsphere, and epoxy silane crosslinking agent;

[0058] Step S2 specifically includes:

[0059] Step S21, dissolving PI-Si in NMP N-methyl pyrrolidone for stirring to obtain a first solution;

[0060] Step S22, pretreating h-BN, SiC-NWs, and silica@Ag;

[0061] Step S23, sequentially adding the pretreated h-BN, SiC-NWs and silica@Ag in the first solution for ultrasonic dispersion to obtain a second solution;

[0062] Step S24, stirring the crosslinking agent in the second solution to obtain a molding solution.

[0063] It can be known that, in step S23, by adding the pretreated h-BN, SiC-NWs and silica@Ag in steps, the phase separation caused by the density difference between h-BN and SiC-NWs can be avoided.

[0064] In step S21, the stirring speed is 700-900 rpm, the stirring temperature is 40-60℃, and the stirring time is 1.5-2.5h; preferably, the stirring speed is 800 rpm, the stirring temperature is 50℃, and the stirring time is 2h.

[0065] In step S22, the h-BN is pretreated by vacuum drying at 50-70℃ for 3-5h, the SiC-NWs are pretreated by etching with 3-8% hydrofluoric acid for 3-7min, and the silica@Ag is pretreated by ultrasonic dispersion in an ethanol mixture for 10-20min; preferably, the h-BN is pretreated by vacuum drying at 60℃ for 4h, the SiC-NWs are pretreated by etching with 5% hydrofluoric acid for 5min, and the silica@Ag is pretreated by ultrasonic dispersion in an ethanol mixture for 15min.

[0066] Specifically, the pretreatment of h-BN is used to remove the adsorbed water on its surface, so that its water content is ≤0.1%, preventing uneven dispersion due to surface impurities in subsequent ultrasonic dispersion, and reducing thermal and mechanical properties; after etching the SiC-NWs, they are washed to neutral with deionized water and dried with hot air at 60℃, which can remove the surface oxide layer to improve the interfacial bonding with PI-Si in ultrasonic dispersion, so that it is more uniformly dispersed in the second solution; after placing the silica@Ag in an ethanol mixture with a volume ratio of ethanol to water of 7:3 and adding CTAB, the silica@Ag reduces the surface tension of the water phase under the action of the ethanol mixture, which can promote the dispersion of silica@Ag, and a small amount of water in the ethanol mixture provides a polar environment, increasing the absorption effect of CTAB, and the addition of CTAB can prevent the aggregation of silica@Ag through electrostatic repulsion, thereby improving the quality of the second solution.

[0067] In step S23, the ultrasonic dispersion power is 250-350W, and the time is 1.5-3h; preferably, the ultrasonic dispersion power is 300W, and the time is 2h.

[0068] It can be known that by performing ultrasonic dispersion, the h-BN, SiC-NWs and silica@Ag can be uniformly dispersed in the first solution, agglomeration of the h-BN, SiC-NWs and silica@Ag is avoided, the interfacial bonding strength is improved, and a stable second solution is ensured to be formed.

[0069] In step S24, the mass ratio of PI-Si, h-BN, SiC-NWs, silica@Ag and crosslinking agent in the forming solution is 55-65:20-30:8-12:3-5:0.8-1.2, the stirring time is 10-15 min, and the stirring speed is 200-400 rpm; preferably, the mass ratio of PI-Si, h-BN, SiC-NWs, silica@Ag and crosslinking agent in the forming solution is 60:25:10:4:1, the stirring time is 10 min, and the stirring speed is 200 rpm.

[0070] In step S3, the forming solution is coated on the coating area of the substrate 1 by the magnetic suspension spraying device.

[0071] The forming solution is injected into the magnetic suspension spraying device, and the magnetic field generated by the magnetic suspension spraying device is perpendicular to the coating area. Then, the magnetic suspension spraying device carries the spray head through the multi-axis mechanical arm, and the forming solution is sprayed on the coating area by nitrogen driving. At the same time, the forming solution is also electrostatically atomized to form droplets when it is sprayed out of the spray head, and is deposited on the coating area under the action of the magnetic field.

[0072] It should be noted that the forming solution can be fully deposited on the coating surface of the substrate 1 by the magnetic suspension spraying device. After the forming solution is electrostatically atomized, the forming solution is positively charged. Then, the positively charged forming solution droplets are constrained by the Lorentz force under the action of the magnetic field formed by the magnetic suspension spraying device, so that the forming solution droplets are vertically oriented along the magnetic induction lines. Under the action of the magnetic field, the h-BN in the forming solution is arranged in the plane along the low magnetic field gradient direction by the magnetization force, the SiC-NWs extend along the magnetic field direction in the magnetic field, the interface thermal resistance is reduced by the bridging h-BN, and the silica@Ag is self-assembled into a close-packed photonic crystal structure on the droplet surface by the fluid force and surface tension.

[0073] In addition, by spraying the forming solution through the magnetic suspension spraying device, the deposition trajectory of the forming solution droplets can be controlled under the synergistic control of the magnetic field and the electric field, full coating is achieved, and the positively charged forming solution droplets move along the direction parallel to the magnetic induction lines under the lateral force in the magnetic field, so that the forming solution droplets only cover the coating area, avoiding random diffusion of the forming solution and pollution of other areas of the substrate 1.

[0074] It should be noted that during the coating process, the high-precision camera on the multi-axis mechanical arm can identify the position of the touch sensor 4 solder point on the coated surface of the substrate 1 to dynamically adjust the spraying trajectory to ensure that the formed solution droplets sprayed in the coating area maintain a safety distance of ≥0.1 mm from the touch sensor 4 solder point to avoid short circuit caused by the formed solution droplets forming a conductive path.

[0075] It can be known that by maintaining a safety distance between the formed solution droplets and the touch sensor 4 solder point, the short circuit caused by the adjacent touch sensor 4 solder points due to the formed solution droplets forming a conductive path can be avoided, and the problem of the solder being unable to directly contact the pad after the protective film layer is subsequently formed, resulting in a virtual weld or falling off, can also be avoided.

[0076] It can be understood that the multi-axis mechanical arm carrying the spray head and high-precision camera and the formation of the magnetic field on the magnetic suspension spraying equipment are well known to those skilled in the art, and this embodiment will not be described.

[0077] The magnetic field strength is 0.3-0.7T, the spraying pressure is 0.2-0.5MPa, the spraying speed is 15-30mm / s, and the spraying interval is 10-20cm; preferably, the magnetic field strength is 0.5T, the spraying pressure is 0.3MPa, the spraying speed is 20mm / s, and the spraying interval is 15cm.

[0078] Specifically, after the forming solution is electrostatically atomized, the forming solution droplet particle size is ≤10μm.

[0079] Step S4, the forming solution in the coating area is step-cured to form a protective film layer with a PI-Si dense layer, a h-BN / SiC-NWs / PI-Si composite fiber network layer, and a photonic crystal microsphere close-packed layer.

[0080] It should be noted that the PI-Si dense layer, the h-BN / SiC-NWs / PI-Si composite fiber network layer, and the photonic crystal microsphere close-packed layer are sequentially distributed towards the substrate 1, the PI-Si dense layer provides the protective film layer with substrate 1 adhesion and wet oxygen barrier, which can protect the touch sensor 4 on the substrate 1, the h-BN in the h-BN / SiC-NWs / PI-Si composite fiber network layer is arranged in-plane, forming a continuous heat conduction path, which can effectively conduct the heat generated on the substrate 1 and the touch sensor 4, and the photonic crystal microsphere close-packed layer has high infrared radiation and surface hardening performance, which, together with the h-BN / SiC-NWs / PI-Si composite fiber network layer, allows the protective film layer to not only achieve heat conduction and dissipation, but also further improve the protection effect of the touch sensor 4, thereby achieving both heat dissipation and heat conduction.

[0081] It should be further explained that the protective film layer, through the cooperation of the h-BN / SiC-NWs / PI-Si composite fiber network layer and the photonic crystal microsphere close-packed layer, can realize phonon conduction to improve in-plane thermal conductivity, and further reduce interface thermal resistance under the action of h-BN and SiC-NWs in the h-BN / SiC-NWs / PI-Si composite fiber network layer, and reduce temperature through radiation heat dissipation under the action of the photonic crystal microsphere close-packed layer, which can effectively dissipate heat for the substrate 1 and the touch sensor 4, and the surface structure in the photonic crystal microsphere close-packed layer further improves the protection effect of the protective film layer.

[0082] Step S4 specifically includes:

[0083] Step S41, heat curing the molding solution at 70-90°C for 20-40 min;

[0084] Step S42, infrared radiation curing the molding solution treated in step S41 at 110-130°C for 0.5-2 h;

[0085] Step S43, laser scanning curing the molding solution treated in step S43 at 140-160°C for 5-15 min, to obtain the protective film layer.

[0086] Preferably, step S4 specifically includes:

[0087] Step S41, heat curing the molding solution at 80°C for 30 min;

[0088] Step S42, heat curing the molding solution treated in step S41 at 120°C for 1 h;

[0089] Step S43, heat curing the molding solution treated in step S42 at 150°C for 10 min, to obtain the protective film layer.

[0090] It should be noted that the forming solution is initially cross-linked by hot air mild curing to form a mechanical skeleton, so that the h-BN and the SiC-NWs are initially distributed, the migration or agglomeration of the h-BN and the SiC-NWs during subsequent high-temperature curing is prevented, the viscosity of the forming solution is prevented from suddenly decreasing, the h-BN and the SiC-NWs are prevented from quickly settling due to the density difference and causing delamination, the in-plane thermal conductivity is reduced, and the close-packed structure of the silica@Ag is pre-cured to improve the subsequent curing effect. Then, the infrared radiation curing activates the silane cross-linking reaction, so that the h-BN and the PI-Si in the forming solution are combined through the Si-O-Si bond. The heat absorption efficiency of the PI-Si, the h-BN, the SiC-NWs and the silica@Ag is improved, and the heat absorption efficiency of the substrate 1 is reduced, so that the substrate 1 is prevented from overheating during thermal curing, and uniform cross-linking is achieved through the penetration effect of the infrared radiation. Finally, the forming solution is locally thermoplastically deformed through laser scanning curing, the internal stress caused by the difference in expansion coefficients is eliminated, the warping of the protective film layer is avoided, and the adhesion of the protective film layer is enhanced.

[0091] In addition, the coating surface of the substrate 1 is heated by the above-mentioned step curing method, so that the temperature of the front surface of the substrate 1 is ≤60℃, so as to protect the touch layer and the display module on the substrate 1. In addition, during the thermal curing process, air cooling can be assisted on the other surfaces of the substrate 1 to prevent the touch layer IC or the flexible circuit on the substrate 1 from failing due to heat. After the curing is completed, the nitrogen gas knife can be used to cool the cured protective film layer and the substrate 1 at a cooling rate of 20℃ / min, so as to prevent the substrate 1 from being deformed due to heat.

[0092] Specifically, the PI-Si is initially cross-linked by the curing in step S41, the h-BN is arranged in the plane by the residual force of the magnetic field, and the silica@Ag is floated to the surface layer of the forming solution by Brownian motion. Then, the Si-O-Si covalent bond network is densified by the curing in step S42, so that the h-BN and the PI-Si are combined through the silane bond, the SiC-NWs bridge adjacent h-BN, and the h-BN is in the middle. Finally, the PI-Si chain segment is relaxed by local high temperature in step S43, the interface chemical bond is reorganized, and the internal stress is eliminated.

[0093] It can be known that the infrared radiation curing is used in step S42, the C=O and Si-O bond vibration frequency of the PI-Si is matched, resonance heating is triggered, and the cross-linking reaction is preferentially activated. In step S43, the laser is selectively absorbed by the SiC-NWs to achieve local heating, the PI-Si hardly absorbs heat to achieve precise temperature control, the protective film layer is prevented from warping, and the moisture and oxygen barrier property of the protective film layer is guaranteed.

[0094] S5, coating optical transparent adhesive on the protective film layer, and forming a substrate after curing to obtain an OCA substrate touch screen.

[0095] The above-described and above-embodied examples are only used to illustrate the technical solutions of the present application, but not to limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features thereof can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An OCA-based touchscreen, characterized in that, It includes a substrate (1), a protective layer (2) and a base (3) connected in sequence. The protective layer (2) is disposed on the side of the substrate (1) where the touch sensor (4) is located. The protective layer (2) includes a protective layer (21), a thermally conductive layer (22) and a thermally radiating layer (23) connected in sequence. The protective layer (21) is a PI-Si dense layer, the thermally conductive layer (22) is an h-BN / SiC-NWs / PI-Si composite fiber network layer, and the thermal radiation layer (23) is a photonic crystal microsphere densely packed layer.

2. The OCA substrate touchscreen according to claim 1, characterized in that, The thickness of the protective layer (21) is 2 μm, the thickness of the thermally conductive layer (22) is 15 μm, and the thickness of the thermal radiation layer (23) is 3 μm.

3. A method for fabricating an OCA substrate touchscreen, characterized in that, The method for fabricating an OCA substrate touchscreen as described in any one of claims 1-2 includes the following steps: Step S1: Provide a substrate with a coated surface on one side corresponding to the touch sensor; Step S2: Prepare a molding solution by mixing PI-Si, h-BN, SiC-NWs, silica@Ag and epoxy silane crosslinking agent; Step S3: Apply the molding solution to the coating area of ​​the substrate using a magnetic levitation spraying device; Step S4: Perform step thermal curing on the molding solution in the coating area to form a protective film layer with a dense PI-Si layer, an h-BN / SiC-NWs / PI-Si composite fiber network layer and a densely packed photonic crystal microsphere layer. Step S5: Apply optically transparent adhesive to the protective film layer and allow it to cure to form a substrate, thus obtaining an OCA substrate touch screen.

4. The method for fabricating an OCA substrate touchscreen according to claim 3, characterized in that, Step S2 specifically includes: Step S21: Dissolve PI-Si in NMP and stir to obtain the first solution; Step S22: Pretreatment of h-BN, SiC-NWs and silicon dioxide@Ag; Step S23: Add pretreated h-BN, SiC-NWs and silica@Ag sequentially to the first solution and disperse them by ultrasonication to obtain the second solution; Step S24: Stir the crosslinking agent in the second solution to obtain the molding solution.

5. The method for fabricating an OCA substrate touchscreen according to claim 4, characterized in that, In step S21, the stirring speed is 700-900 rpm, the stirring temperature is 40-60℃, and the stirring time is 1.5-2.5 h. In step S22, h-BN is pretreated by vacuum drying at 50-70℃ for 3-5 hours, SiC-NWs is pretreated by etching with 3-8% hydrofluoric acid for 3-7 minutes, and silicon dioxide@Ag is pretreated by ultrasonic dispersion in an ethanol mixture for 10-20 minutes. In step S23, the power of ultrasonic dispersion is 250-350W, and the time is 1.5-3h; In step S24, the mass ratio of PI-Si, h-BN, SiC-NWs, silicon dioxide@Ag and crosslinking agent in the molding solution is (55-65):(20-30):(8-12):(3-5):(0.8-1.2), the stirring time is 10-15 min, and the stirring speed is 200-400 rpm.

6. The method for fabricating an OCA substrate touchscreen according to claim 3, characterized in that, The molding solution is injected into the magnetic levitation spraying equipment, and the magnetic field generated by the magnetic levitation spraying equipment is perpendicular to the coating area. Then, the magnetic levitation spraying equipment carries the nozzle through a multi-axis robotic arm and is driven by nitrogen to spray the molding solution onto the coating area. At the same time, when the molding solution is sprayed out by the nozzle, it is also electrostatically atomized to form droplets, which are deposited on the coating area under the action of the magnetic field.

7. The method for fabricating an OCA substrate touchscreen according to claim 6, characterized in that, The magnetic field strength is 0.3-0.7T, the spraying pressure is 0.2-0.5MPa, the spraying speed is 15-30mm / s, and the spraying spacing is 10-20cm.

8. The method for fabricating an OCA substrate touchscreen according to claim 3, characterized in that, Step S4 specifically includes: Step S41: Curing the molding solution with hot air at 70-90℃ for 20-40 minutes; Step S42: Curing the molding solution treated in step S41 with infrared radiation at 110-130℃ for 0.5-2 hours; Step S43: The molding solution treated in step S42 is subjected to laser scanning curing at 140-160℃ for 5-15 minutes to obtain a protective film layer.

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