Flexible foldable cover plate for touch screen and touch screen

Abstract

This application discloses a flexible foldable cover plate for a touchscreen and a touchscreen itself, relating to the field of touchscreen technology. The flexible foldable cover plate for a touchscreen provided in this application includes a polyimide substrate and a front hardening layer formed by applying a hardening liquid to the front side of the substrate using a wet coating process, and a back hardening layer formed by applying a hardening liquid to the back side of the substrate. The front hardening layer is exposed outside the touchscreen and its surface hardness is greater than that of the back hardening layer. The hardness of the back hardening layer is greater than that of the substrate. The hardness of the front hardening layer, the back hardening layer, and the substrate are all lower than the surface hardness of the glass substrate. The touchscreen includes the flexible foldable cover plate for a touchscreen provided in this application. This invention aims to increase the bending capacity of the substrate and the touchscreen using the substrate.

Description

Technical Field

[0001] This application relates to the field of touch screen technology, and more specifically, it relates to a flexible foldable cover for a touch screen and a touch screen. Background Technology

[0002] A touchscreen is a touch-sensitive liquid crystal display device that can receive control signals triggered by a finger. When a finger touches the screen, the haptic feedback system on the screen can drive various functional modules according to a pre-programmed program, thereby enabling the control of the device using the touchscreen and the display of images.

[0003] The cover plate is an important component of the touch screen, as it is exposed on the outermost side of the touch screen and directly receives the touch of a person's hand.

[0004] In related technologies, touchscreens include a glass cover and a conductive film. The front of the cover is used for human touch. The back of the cover is connected to the conductive film via OCA adhesive, and the conductive film forms a capacitor within the touchscreen.

[0005] However, the glass substrates in related technologies have the following technical defects:

[0006] In related technologies, glass substrates have poor bendability and insufficient flexibility, and will break when bent, making them unsuitable for flexible and bendable touch screens. Summary of the Invention

[0007] In order to improve the bendability of the touch screen cover and increase the flexibility of the touch screen so that it can be applied to flexible touch screens, this application provides a flexible foldable cover for a touch screen and a touch screen.

[0008] In a first aspect, this application provides a flexible foldable cover for a touch screen, employing the following technical solution:

[0009] A flexible foldable cover for a touch screen includes a polyimide substrate and a front hardening layer formed by applying a curing liquid to the front side of the substrate using a wet coating process, and a back hardening layer formed by applying a curing liquid to the back side of the substrate using a wet coating process. The front hardening layer is exposed outside the touch screen and its surface hardness is greater than that of the back hardening layer. The hardness of the back hardening layer is greater than that of the substrate. The hardness of the front hardening layer, the back hardening layer, and the substrate is all lower than the surface hardness of the glass substrate.

[0010] In this application, the hardness of the polyimide substrate, as well as the front and back hardening layers, is lower than the surface hardness (above 6H) of the glass substrate in related technologies. This ensures that the flexible foldable cover for touch screens, composed of the substrate, the front hardening layer, and the back hardening layer, has stronger bending performance, is more flexible, and can withstand more bending cycles. The cover prepared by the preferred scheme can withstand more than 100,000 bending cycles. At the same time, the front and back hardening layers can fill the rough surface of the polyimide substrate to a certain extent, thereby improving the overall light transmittance of the cover. Since the front hardening layer has a relatively higher hardness, it also improves the wear resistance of the cover.

[0011] Preferably, the curing liquid is formulated from the following raw materials in weight percentages: aliphatic polyurethane acrylic resin: 20%–40%;

[0012] Organosilicon polymers: 10%–20%;

[0013] Ethylene glycol monobutyl ether: 30%–50%;

[0014] Methyl isobutyl ketone: 10%–15%;

[0015] Hardener: 0.5%~1%.

[0016] The desired hardening liquid can be obtained by mixing the above raw materials and stirring them evenly without any chemical reaction.

[0017] The above-mentioned raw material, aliphatic polyurethane acrylic resin, can also be called aliphatic polyurethane acrylic resin prepolymer. As the main component of the hardener, aliphatic polyurethane acrylic resin exhibits good heat resistance and flexural strength, while also showing strong adhesion to polyimide substrates. Organosilicon polymers possess good heat resistance and mechanical properties, and can also improve the slip properties of the hardener. Ethylene glycol monobutyl ether and methyl isobutyl ketone can reduce the viscosity of the aliphatic polyurethane acrylic resin before baking and curing, while the curing agent can increase the speed of baking and curing.

[0018] Preferably, the organosilicon polymer is an epoxy-containing organosilicon alkane, and the curing agent is diaminodiphenyl sulfone DDS HT-976.

[0019] Ethylene glycol monobutyl ether and epoxy-containing organosiloxanes are both stable organic solvents with strong dissolving power, which can effectively prevent the curing solution from solidifying before wet coating. Diaminodiphenyl sulfone (DDS) HT-976 can effectively promote the curing of the curing solution on the substrate surface to form a hardened layer.

[0020] Preferably, the edge of the back hardened layer is further provided with a frame shielding layer made of light-shielding material; the frame shielding layer is used to shield the conductive electrode at the edge of the transparent conductive film bonded to the flexible foldable cover plate for the touch screen and the flexible ribbon cable connected to the conductive electrode.

[0021] The bezel shielding layer can prevent conductive electrodes and flexible cables from being exposed, thereby improving the aesthetics of the touchscreen and providing decorative benefits.

[0022] Preferably, the light-shielding material is black insulating ink, and the light-shielding material is printed on the edge of the hardened back layer using a printing process. The insulating ink has insulating properties, which can prevent current leakage between the conductive electrodes and the flexible cable.

[0023] Preferably, the thickness of the front hardening layer is 2-4 times the thickness of the back hardening layer.

[0024] The greater the thickness, the higher the hardness. The above thickness ensures that the hardness of the front hardened layer is greater than that of the back hardened layer.

[0025] Preferably, the thickness of the front hardening layer is 200nm to 400nm, and the thickness of the back hardening layer is 100nm to 200nm. A larger thickness results in higher hardness; the above thicknesses ensure that the hardness of the front hardening layer is greater than that of the back hardening layer, thus meeting the requirements for touchscreen use.

[0026] Preferably, the thickness of the substrate is 30 micrometers to 300 micrometers. The wet coating process includes a baking step, wherein the baking temperature is 120°C to 160°C, preferably around 140°C.

[0027] The above thickness ensures that the substrate has high flexibility and bending resistance while meeting the requirements of touch function for light transmittance and strength.

[0028] Preferably, the surface hardness of the front hardened layer is 5H or higher, and the surface hardness of the glass substrate is 6H or higher, measured using the coating hardness pencil test method.

[0029] When the surface hardness of the cover plate is high, the wear resistance is better, but the bending resistance will be reduced. The technical solution provided in this application achieves a reasonable balance between bending resistance and wear resistance.

[0030] This application provides a touch screen, which includes a conductive film and a flexible foldable cover plate for the touch screen provided by any of the technical solutions in this application, wherein:

[0031] The hardened back layer of the flexible foldable cover for the touch screen is connected to the conductive film by adhesive, and the conductive film forms a capacitor within the touch screen.

[0032] When used in a touchscreen, this application ensures that the cover plate can withstand multiple (preferred solutions can support more than 100,000) bends without breaking.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. In this application, the hardness of the polyimide substrate and the front and back hardening layers are all lower than the surface hardness (6H or higher) of the glass substrate in related technologies. This ensures that the flexible foldable cover for touch screens, which is composed of the substrate, the front hardening layer, and the back hardening layer, has stronger bending performance, is more flexible, and can withstand more bending cycles. The cover prepared by the preferred scheme can withstand more than 100,000 bending cycles. At the same time, the front hardening layer and the back hardening layer can fill the rough surface of the polyimide substrate to a certain extent, thereby improving the overall light transmittance of the cover. Since the front hardening layer has a relatively higher hardness, it also improves the wear resistance of the cover.

[0035] 2. Aliphatic polyurethane acrylic resin, as the main component of the hardener, possesses good heat resistance and flexural strength, and also exhibits strong adhesion to polyimide substrates. Organosilicon polymers improve the slip properties of the hardener, while ethylene glycol monobutyl ether and methyl isobutyl ketone reduce the viscosity of the aliphatic polyurethane acrylic resin before baking and UV curing, thus preventing natural hardening. The curing agent can increase the speed of curing during baking and heating.

[0036] 3. Both ethylene glycol monobutyl ether and epoxy-containing organosiloxanes are stable and highly effective solvents, which can effectively prevent the curing solution from solidifying before wet coating. Diaminodiphenyl sulfone (DDS) HT-976 can effectively promote the curing of the curing solution on the substrate surface to form a hardened layer;

[0037] 4. When the surface hardness of the cover plate is high, the wear resistance is better, but the bending resistance will be reduced. The technical solution of this application achieves a reasonable balance between bending resistance and wear resistance. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the cross-sectional (layer) structure of the flexible foldable cover plate for touch screen provided by the present invention;

[0039] Figure 2 This is a schematic diagram of the back hardening layer of the flexible foldable cover plate for touch screen provided by the present invention;

[0040] Figure 3 This is a schematic diagram of the back hardened layer of the flexible foldable cover plate of the touch screen provided by the present invention after the conductive film is connected.

[0041] The markings in the diagram are: 1. Border shielding layer; 2. Conductive electrode (nano silver); 3. Flexible ribbon cable; 4. Back hardening layer; 5. Substrate; 6. Front hardening layer. Detailed Implementation

[0042] The present application will be further described in detail below with reference to the embodiments.

[0043] The following is in conjunction with the appendix Figure 1-3 The present application will be further described in detail with reference to the embodiments.

[0044] This application develops a flexible foldable cover using a transparent polyimide material PI (CPI) with a curing coating. Aliphatic polyurethane acrylic resin and organosilicon polymer are selected as the main effective components of the curing liquid. The proportion of additives, water and gas barrier functions, bending times, transmittance and folding performance are studied, analyzed and selected. Suitable raw materials are selected to prepare a bend-resistant foldable cover, realizing the application of a new type of optical PET film for foldable covers.

[0045] like Figure 1 As shown, this application provides a flexible foldable cover for a touchscreen, comprising four layers, from the inside out: a frame shielding layer 1, a back hardening layer 4, a polyimide (CPI) substrate 5, and a front hardening layer 6. The front hardening layer 6 and the back hardening layer 4 are formed by applying a hardening liquid to the front and back of the substrate 5 respectively using a wet coating process. The front hardening layer 6 is exposed outside the touchscreen and its surface hardness is greater than that of the back hardening layer 4. The hardness of the back hardening layer 4 is greater than that of the substrate 5. The hardness of the front hardening layer 6, the back hardening layer 4, and the substrate 5 is all lower than the surface hardness of the glass substrate. The frame shielding layer 1, made of a light-shielding material, is disposed along the edge of the back hardening layer 4.

[0046] In this application, the hardness of the polyimide substrate 5, the front hardening layer 6, and the back hardening layer 4 are all lower than the hardness of the glass substrate (6H or higher) in related technologies. This ensures that the flexible foldable cover plate for touch screens, composed of the substrate 5, the front hardening layer 6, and the back hardening layer 4, has stronger bending performance, is more flexible, and can withstand more bending cycles. The cover plate prepared by the preferred scheme can withstand more than 100,000 bending cycles. At the same time, the front hardening layer 6 and the back hardening layer 4 can fill the rough surface of the polyimide substrate 5 to a certain extent, thereby improving the overall light transmittance of the cover plate. Since the front hardening layer 6 has a relatively higher hardness, it also improves the wear resistance of the cover plate.

[0047] As an optional implementation, the hardening liquid is formulated from the following raw materials in weight percentages:

[0048] Aliphatic polyurethane acrylic resin: 20%–40%;

[0049] Organosilicon polymers: 10%–20%;

[0050] Ethylene glycol monobutyl ether: 30%–50%;

[0051] Methyl isobutyl ketone: 10%–15%;

[0052] Hardener: 0.5%~1%.

[0053] The above weight percentage values ​​include the values ​​at both ends of the range, and the preferred weight percentage value is the midpoint of the range.

[0054] The desired hardening liquid can be obtained by mixing the above raw materials and stirring them evenly without any chemical reaction.

[0055] The above-mentioned aliphatic polyurethane acrylic resin can also be called aliphatic polyurethane acrylic resin prepolymer. As the main component of the hardener, the aliphatic polyurethane acrylic resin exhibits good heat resistance and flexural strength, and also demonstrates strong adhesion to the polyimide substrate 5 after curing. The silicone polymer improves the slip properties of the hardener, while ethylene glycol monobutyl ether and methyl isobutyl ketone reduce the viscosity of the aliphatic polyurethane acrylic resin before baking and UV curing. The curing agent can increase the curing speed of the hardener.

[0056] As an optional implementation, the organosilicon polymer is an epoxy-containing organosiloxane, and the curing agent is diaminodiphenyl sulfone DDS HT-976.

[0057] Ethylene glycol monobutyl ether and epoxy-containing organosiloxanes are both stable organic solvents with strong dissolving power, which can effectively prevent the curing solution from solidifying before wet coating, thus ensuring the curing effect. Diaminodiphenyl sulfone (DDS) HT-976 can effectively promote the curing of the curing solution on the surface of substrate 5 to form a hardened layer.

[0058] like Figure 2 and Figure 3 As shown, the transparent conductive film is bonded to the flexible foldable cover plate for the touch screen, and the frame shielding layer 1 is used to shield the conductive electrode 2 at the edge of the transparent conductive film and the flexible ribbon cable 3 connected to the conductive electrode 2.

[0059] The bezel shielding layer 1 can prevent the conductive electrodes 2 and flexible ribbon cable 3 from being exposed, thereby improving the aesthetics of the touch screen and having decorative properties.

[0060] As an optional implementation, the light-shielding material is black insulating ink, which is printed on the edge of the back hardened layer 4 using a printing process. The insulating ink has insulating properties, which can prevent current leakage from the conductive electrode 2 and the flexible cable 3.

[0061] As an optional implementation, the thickness of the front hardening layer 6 is 2-4 times the thickness of the back hardening layer 4. The greater the thickness of the hardening layer, the higher its hardness; the above thickness ensures that the hardness of the front hardening layer 6 is greater than that of the back hardening layer 4.

[0062] As an optional implementation, the thickness of the front hardening layer 6 is 200nm to 400nm, and the thickness of the back hardening layer 4 is 100nm to 200nm. The greater the thickness, the higher the hardness. The above thickness dimensions ensure that the hardness of the front hardening layer 6 is greater than that of the back hardening layer 4, and meet the requirements for touch screen use.

[0063] As an alternative implementation, the thickness of the substrate 5 is 30 micrometers to 300 micrometers.

[0064] The wet coating process in this application includes a baking step, with the baking temperature being 120°C-160°C, preferably around 140°C.

[0065] The above thickness ensures that the substrate 5 has high flexibility and bending resistance, while meeting the requirements of touch function for light transmittance and strength.

[0066] As an optional implementation, the hardness of the outer surface of the front hardened layer 6 is measured using the coating hardness pencil test method, and the surface hardness of the glass substrate is 5H or higher.

[0067] When the surface hardness of the cover plate is high, the wear resistance is better, but the bending resistance will be reduced. This application achieves a reasonable balance between bending resistance and wear resistance.

[0068] This application provides a touch screen, which includes a conductive film and any of the technical solutions provided in this application, such as... Figure 1 and Figure 2 The flexible foldable cover plate shown is for a touch screen, wherein:

[0069] The back hardened layer 4 of the flexible foldable cover for the touch screen is connected to the (transparent) conductive film by an adhesive (preferably OCA adhesive), and the (transparent) conductive film forms a capacitor in the touch screen.

[0070] When used in a touchscreen, this application ensures that the cover plate can withstand multiple (preferred solutions can support more than 100,000) bends without breaking.

[0071] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A flexible foldable cover for a touch screen, characterized in that: The invention includes a polyimide substrate and a front hardening layer formed by applying a curing liquid to the front side of the substrate using a wet coating process, and a back hardening layer formed by applying a curing liquid to the back side of the substrate using a wet coating process. The thickness of the front hardening layer is 200nm to 400nm, the thickness of the back hardening layer is 100nm to 200nm, the thickness of the front hardening layer is 2 to 4 times the thickness of the back hardening layer, the thickness of the substrate is 30μm to 300μm, the front hardening layer is exposed outside the touch screen and its surface hardness is greater than that of the back hardening layer, the hardness of the back hardening layer is greater than that of the substrate, and the hardness of the front hardening layer, the back hardening layer and the substrate are all lower than the surface hardness of the glass substrate. The hardening liquid is formulated from the following raw materials in weight percentages: Aliphatic polyurethane acrylic resin: 20%–40%; Organosilicon polymers: 10%–20%; Ethylene glycol monobutyl ether: 30%–50%; Methyl isobutyl ketone: 10%–15%; Hardener: 0.5%–1%; The organosilicon polymer is an epoxy-containing organosilicon alkane, and the curing agent is diaminodiphenyl sulfone DDS HT-976.

2. The flexible foldable cover for a touch screen according to claim 1, characterized in that: The edge of the back hardened layer is also provided with a frame shielding layer made of light-shielding material; The frame shielding layer is used to shield the conductive electrodes at the edge of the transparent conductive film bonded to the flexible foldable cover plate for the touch screen, as well as the flexible ribbon cable connected to the conductive electrodes.

3. A flexible foldable cover for a touchscreen according to claim 2, characterized in that: The light-shielding material is black insulating ink, and the light-shielding material is printed on the edge of the hardened layer on the back using a printing process.

4. A flexible foldable cover for a touch screen according to claim 1, characterized in that: The wet coating process includes a baking step, with a baking temperature of 120-160°C.

5. A flexible foldable cover for a touch screen according to claim 1, characterized in that: The surface hardness of the front hardened layer is 5H or higher, and the surface hardness of the glass substrate is 6H or higher, as measured by the pencil hardness test method.

6. A touch screen, characterized in that: The touchscreen includes a conductive film and a flexible, foldable cover plate for a touchscreen as described in any one of claims 1-5, wherein: The hardened back layer of the flexible foldable cover for the touch screen is connected to the conductive film by adhesive, and the conductive film forms a capacitor within the touch screen.

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