Screen printing methods for UTG and UTG protective films

Abstract

This application discloses a screen printing process and a UTG protective film applicable to UTG. The screen printing method for UTG includes the following steps: S1, surface cleanliness treatment of the ultra-thin flexible glass; S2, printing an ink layer around the periphery of the layer to be printed on the ultra-thin flexible glass. The ink layer is formed by an ink comprising the following components by weight: acid-resistant epoxy resin: 48-52 parts; acid-resistant pigment: 13-17 parts; alcohol ether solvent: 27-31 parts; leveling agent: 0.4-0.6 parts; defoamer: 0.4-0.6 parts; curing agent: 4-6 parts; S3, curing the ultra-thin flexible glass printed with the ink at a temperature of 80℃-110℃. After curing, the thickness of the ink layer is 0.5μm–1μm. This application can form an ink layer of 0.5μm–1μm and ensures reliable bonding between the ink layer and the ultra-thin flexible glass, solving the technical problem of ink layer easily detaching after repeated bending.

Description

Technical Field

[0001] This invention relates to the field of ultrathin flexible glass, and more specifically to a screen printing method suitable for UTG and a UTG protective film. Background Technology

[0002] With the rapid development of flexible electronic devices such as foldable screens and rollable screens, ultra-thin glass (UTG) has become a core cover material due to its excellent surface hardness, optical properties and barrier properties.

[0003] However, screen printing on ultrathin flexible glass (typically 30μm-100μm) faces challenges that traditional processes cannot overcome. First, the smooth and chemically inert surface of glass results in poor wetting and adhesion of conventional inks, making the printed pattern prone to peeling off during use (especially after repeated bending). Furthermore, existing ink thermosetting processes typically employ high curing temperatures (e.g., above 120°C), which introduce significant thermal stress due to the mismatch in thermal expansion coefficients between the ultrathin flexible glass and the ink layer. This can lead to glass deformation or a decrease in the bonding strength between the printed layer and the glass interface, severely impacting the bending reliability of the final product. Summary of the Invention

[0004] To address the above-mentioned problems and overcome at least one deficiency, this invention proposes a screen printing process suitable for UTG and a UTG protective film.

[0005] The technical solution adopted in this invention is as follows:

[0006] A screen printing method suitable for UTG includes the following steps: S1. Perform surface cleanliness treatment on ultra-thin flexible glass; S2. Print an ink layer around the periphery of the ultra-thin flexible glass layer to be printed, the ink layer being formed of an ink comprising the following components in parts by weight: Acid-resistant epoxy resin: 48-52 parts; Acid-resistant pigment: 13-17 parts; Alcohol ether solvents: 27-31 parts; Leveling agent: 0.4-0.6 parts; Defoamer: 0.4-0.6 parts; Hardener: 4-6 parts; S3. The ultra-thin flexible glass printed with the ink is cured at a temperature of 80℃-110℃. After curing, the thickness of the ink layer is 0.5μm-1μm.

[0007] By performing surface cleanliness treatment on ultra-thin flexible glass and using specific inks containing acid-resistant resins, the wettability and chemical adhesion of the ink on the glass surface are improved. The components of the ink formulation in this application work synergistically to form a cured ink layer with good flexibility, strong adhesion, and chemical resistance. Furthermore, by employing a low-temperature curing process of 80℃-110℃, thermal shock caused by high-temperature curing and residual stress resulting from mismatched coefficients of thermal expansion are effectively avoided, ensuring a reliable bond between the ink layer and the ultra-thin flexible glass. The ink layer adhesion of this application reaches a 5B level in the cross-cut adhesion test and maintains a level of 4B or higher after 200,000 bends, solving the technical problem of ink layers easily detaching after repeated bending.

[0008] In one embodiment of the present invention, the acid-resistant epoxy resin is a bisphenol A type epoxy resin, which is prepared by reacting bisphenol A with epichlorohydrin, and the mass ratio of bisphenol A to epichlorohydrin is 1:(2.8-4.7). The acid-resistant pigment is carbon black, ultramarine, or phthalocyanine blue. The alcohol ether solvent is at least one of diethylene glycol butyl ether, propylene glycol methyl ether, and propylene glycol methyl ether acetate; The leveling agent is a siloxane; The defoamer is at least one of modified silicone oil and hydrophobic silica; The curing agent is at least one of modified phosphoric acid, salicylic acid, and benzoic acid.

[0009] Ultra-thin flexible glass is extremely thin and has low mechanical strength, making it prone to micro-cracks or direct breakage under printing pressure and holding tension, resulting in low production yield. In one embodiment of the present invention, in step S2, a non-contact suction platform is used to adsorb and fix the ultra-thin flexible glass, and then ink is printed on the ultra-thin flexible glass using a wire mesh printing plate. The printing pressure of the wire mesh printing plate is 8 N / cm²–15 N / cm².

[0010] By using a non-contact suction platform to adsorb and fix ultra-thin flexible glass, the contact stress of mechanical clamps is avoided, which significantly reduces the risk of mechanical damage to ultra-thin flexible glass during fixing and printing. This reduces the breakage rate from more than 15% in traditional methods to less than 1%, greatly improving the production yield.

[0011] In one embodiment of the present invention, the wire mesh is a 500-640 mesh wire mesh, and the tension of the wire mesh is 21 N / cm-25 N / cm.

[0012] Using high-mesh, high-tension wire mesh helps achieve high-precision graphic transfer and uniform ink layer thickness control, ensuring printing quality.

[0013] In one embodiment of the present invention, in step S3, the heat preservation time for the curing process is 5-10 minutes.

[0014] During this heat preservation time, the solvent in the ink can slowly and fully evaporate, while the resin and curing agent can undergo a full cross-linking reaction, thereby forming a dense and uniform cured ink layer.

[0015] In one embodiment of the present invention, in step S3, the curing temperature is 100°C and the holding time is 10 minutes.

[0016] This parameter combination is an optimal combination of process parameters that has been experimentally verified. It can minimize thermal stress while ensuring curing effect, thus achieving a balance between performance and efficiency.

[0017] In one embodiment of the present invention, step S1, the surface cleanliness treatment step includes: The ultrathin flexible glass is ultrasonically cleaned using an alkaline cleaning agent, wherein the concentration of the alkaline cleaning agent is 1%±0.2%, the cleaning temperature is 50℃±5℃, and the treatment time is 150s-210s.

[0018] This specific ultrasonic cleaning process can effectively remove oil, particles and other contaminants from the surface of ultra-thin flexible glass, and improve its surface energy, creating favorable conditions for the good adhesion of subsequent inks.

[0019] This application also discloses a UTG protective film, comprising: An ultra-thin flexible glass layer having a first surface and a second surface, wherein the thickness of the ultra-thin flexible glass layer is 30μm-100μm; An ink layer, located at the periphery of the second surface of the ultrathin flexible glass layer, has a thickness of 0.5 μm–1 μm; and An adhesive layer is located on the second surface of the ultrathin flexible glass layer and the outer surface of the ink layer; The ink layer is formed from an ink comprising the following components in parts by weight: Acid-resistant epoxy resin: 48-52 parts; Acid-resistant pigment: 13-17 parts; Alcohol ether solvents: 27-31 parts; Leveling agent: 0.4-0.6 parts; Defoamer: 0.4-0.6 parts; Hardener: 4-6 parts.

[0020] In one embodiment of the present invention, the thickness of the adhesive layer can be 30 μm–50 μm.

[0021] In one embodiment of the present invention, a functional layer located on the first surface of the ultrathin flexible glass layer is also included.

[0022] In practical applications, the functional layer can be an oleophobic layer or a combination of multiple layers, and the adhesive layer can be AB glue or UV glue suitable for ultra-thin flexible glass layers.

[0023] The UTG protective film mentioned in this application can be understood as either a tempered glass film or an ultra-thin glass panel.

[0024] The beneficial effects of this invention are as follows: By performing surface cleanliness treatment on ultra-thin flexible glass and combining it with a specific ink containing acid-resistant resin, the wettability and chemical bonding strength of the ink on the glass surface are improved. The components of the ink formulation in this application work synergistically to form a cured ink layer with good flexibility, strong adhesion, and chemical corrosion resistance. In addition, by using a low-temperature curing treatment at 80℃-110℃, the thermal shock caused by high-temperature curing and the residual stress caused by the mismatch of thermal expansion coefficients are effectively avoided, ensuring a reliable bond between the ink layer and the ultra-thin flexible glass. The ink layer adhesion of this application reaches a 5B level in the cross-cut adhesion test and can still maintain a level of 4B or higher after 200,000 bends, solving the technical problem of ink layers easily falling off after repeated bends. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of ultra-thin flexible glass after an ink layer has been printed on it. Figure 2 This is a schematic diagram of the UTG protective film.

[0026] The labels for the attached figures are as follows: 1. Ultra-thin flexible glass layer; 2. Ink layer; 3. Adhesive layer. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for 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 application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0029] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] This embodiment discloses a screen printing method suitable for UTG, including the following steps: S1. Perform surface cleanliness treatment on ultra-thin flexible glass; S2. Print a specific ink layer around the periphery of the ultra-thin flexible glass layer to be printed; S3. The ultra-thin flexible glass printed with ink is cured at a temperature of 80℃-110℃. After curing, the thickness of the ink layer is 0.5μm-1μm.

[0031] In a preferred embodiment, in step S2, the specific ink layer is formed from an ink comprising the following components in parts by weight: Acid-resistant epoxy resin: 48-52 parts; the acid-resistant epoxy resin is a bisphenol A type epoxy resin, which is prepared by reacting bisphenol A with epichlorohydrin, and the mass ratio of bisphenol A to epichlorohydrin is 1:(2.8-4.7). Acid-resistant pigment: 13-17 parts; the acid-resistant pigment can be carbon black, ultramarine, or phthalocyanine blue. Alcohol ether solvents: 27-31 parts; the alcohol ether solvents may be at least one of diethylene glycol butyl ether, propylene glycol methyl ether (PM), and propylene glycol methyl ether acetate (PMA); Leveling agent: 0.4-0.6 parts; the leveling agent can be siloxane; Defoamer: 0.4-0.6 parts; the defoamer can be at least one of modified silicone oil and hydrophobic silica; Curing agent: 4-6 parts; the curing agent can be at least one of modified phosphoric acid, salicylic acid, and benzoic acid.

[0032] Furthermore, the ink layer can be formed from an ink comprising the following components by weight: 50 parts acid-resistant epoxy resin; 15 parts acid-resistant pigment; 29 parts alcohol ether solvent; 0.5 parts leveling agent; 0.5 parts defoamer; and 5 parts curing agent. This formulation is an experimentally optimized ratio. The 50 parts of acid-resistant epoxy resin provide excellent film-forming properties, adhesion to glass, and resistance to chemical corrosion. The 29 parts of alcohol ether solvent adjust the ink viscosity to a range suitable for high-precision screen printing. Trace amounts of leveling agent and defoamer ensure a smooth, pinhole-free surface of the cured ink layer. The 5 parts of curing agent ensure sufficient cross-linking and curing of the resin at low temperatures. By employing this specific formulation, the resulting ink layer exhibits excellent overall performance in terms of flexibility, adhesion, and chemical resistance.

[0033] The purpose of step S1 is to thoroughly remove oil, dust, and other contaminants from the surface of the ultra-thin flexible glass and improve its surface energy. Existing technologies often overlook the crucial impact of the cleaning process on subsequent adhesion, while this invention, through optimization of this step, creates the prerequisites for a strong bond between the ink and the glass substrate. Effective surface cleaning treatment solves the problem of poor ink wetting and weak adhesion caused by the high chemical inertness and low surface energy of the glass surface. In a preferred embodiment, step S1, the surface cleaning treatment step, includes: Ultrasonic cleaning of ultrathin flexible glass was performed using an alkaline cleaning agent with a concentration of 1% ± 0.2%, a cleaning temperature of 50℃ ± 5℃, and a treatment time of 150s-210s.

[0034] This specific ultrasonic cleaning process effectively removes oil, particles, and other contaminants from the surface of ultra-thin flexible glass, and increases its surface energy, creating favorable conditions for subsequent ink adhesion. Specifically, water-based cleaning agent NH-2000A can be purchased for ultrasonic cleaning.

[0035] Ultra-thin flexible glass is extremely thin and has low mechanical strength, making it prone to micro-cracks or direct breakage under printing pressure and holding tension, resulting in low production yield. In a preferred embodiment, in step S2, a non-contact suction platform is used to adsorb and fix the ultra-thin flexible glass, and then ink is printed on the ultra-thin flexible glass using a wire mesh. The printing pressure of the wire mesh is 8 N / cm²–15 N / cm² (this pressure can prevent the ultra-thin flexible glass from being crushed).

[0036] By using a non-contact suction platform to adsorb and fix ultra-thin flexible glass, the contact stress of mechanical clamps is avoided, which significantly reduces the risk of mechanical damage to ultra-thin flexible glass during fixing and printing. This reduces the breakage rate from more than 15% in traditional methods to less than 1%, greatly improving the production yield.

[0037] In a preferred embodiment, the wire mesh is a 500-640 mesh wire mesh, and the tension of the wire mesh is 21 N / cm-25 N / cm.

[0038] The mesh count of the screen determines the fineness of its openings; high mesh count screens (500+) are fundamental for printing micron-level fine lines. High tension (21-25 N / cm) ensures minimal screen deformation and rapid rebound during printing, allowing the screen to detach instantly from the ink surface after the squeegee passes through, resulting in clear, sharp ink image edges. Precise control of screen parameters solves the problems of blurry image edges and uneven line thickness in traditional processes, enabling high-resolution pattern printing.

[0039] In a preferred embodiment, the heat preservation time for the curing process in step S3 is 5-10 minutes.

[0040] During this heat preservation time, the solvent in the ink can slowly and fully evaporate, while the resin and curing agent can undergo a full cross-linking reaction, thereby forming a dense and uniform cured ink layer.

[0041] In the background art, commonly used high curing temperatures (such as above 120°C) can introduce significant thermal stress due to the mismatch in the coefficients of thermal expansion between the ink layer and the glass substrate. This stress can lead to glass deformation, warping, or defects at the interface, severely weakening the bonding force and reducing the product's bending reliability. This invention uses a low-temperature curing range of 80°C-110°C, significantly reducing thermal stress during the curing process, protecting the ultra-thin flexible glass from heat damage, and ensuring a stable and stress-free interface bond between the ink layer and the substrate, thereby achieving high bending reliability. In a preferred embodiment, in step S3, the curing temperature is 100°C, and the holding time is 10 minutes. This parameter combination is an experimentally verified optimal process parameter combination that can minimize thermal stress while ensuring curing effect, achieving a balance between performance and efficiency.

[0042] The technical solution of the present invention will be described in more detail below with reference to specific embodiments. It should be understood that these embodiments are only used to illustrate the technical solution of the present invention more clearly, and should not be construed as limiting the scope of protection of the present invention.

[0043] In one specific embodiment (Example 1), the present invention provides a screen printing method suitable for UTG, which can be implemented using a series of automated equipment. First, a 70μm thick ultrathin flexible glass (UTG) is selected as the substrate. During the surface cleanliness treatment step, the ultrathin flexible glass is placed in a fully automated ultrasonic cleaning device, using a 1% concentration of NH-2000A alkaline detergent, and cleaned at 50°C for 180 seconds with an ultrasonic intensity set to 0.8A.

[0044] After surface treatment, the treated ultrathin flexible glass is placed on a UTG automatic screen printing machine. This machine is equipped with a rotating worktable that integrates a non-contact suction platform. The ultrathin flexible glass is placed on this platform and, through the negative pressure generated by a precision air pressure control system, is evenly and flatly adsorbed and fixed, without any mechanical clamping throughout the process. Subsequently, the printing head descends, on which a 500-mesh steel wire screen with a tension of 23 N / cm is mounted, and printing is performed at a pressure of 8 N / cm²–15 N / cm². The ink used is formulated strictly according to the following weight ratios: 50 parts of acid-resistant epoxy resin (bisphenol A type epoxy resin, prepared by reacting bisphenol A with epichlorohydrin, with a mass ratio of bisphenol A to epichlorohydrin of 1:3), 15 parts of acid-resistant pigment (carbon black), 29 parts of alcohol ether solvent (diethylene glycol butyl ether), 0.5 parts of leveling agent (siloxane), 0.5 parts of defoamer (modified silicone oil), and 5 parts of curing agent (modified phosphoric acid).

[0045] After printing, a black ink layer with a thickness of about 1 μm is formed on the surface of the UTG substrate 30.

[0046] Finally, the printed ultrathin flexible glass is placed in a heating device and baked at 100°C for 10 minutes to complete the evaporation of the solvent and the cross-linking and curing of the ink. This combination of 100°C and 10 minutes is an optimal combination of process parameters that balances high reliability and production efficiency.

[0047] The ultrathin flexible glass products produced through the above process are as follows: Figure 1As shown, a well-defined and defect-free ink layer 2 is formed on ultra-thin flexible glass (i.e., ultra-thin flexible glass layer 1). The ink layer thickness is 0.8 μm, and the ink layer uniformity is ±0.1 μm. Testing showed that the production yield of this product is greater than 99%, effectively solving the problem of the fragility of ultra-thin flexible glass. The ink adhesion reached a 5B level in the cross-cut adhesion test. After undergoing up to 200,000 dynamic bending tests at a bending radius of R1.5 mm, the screen-printed ink layer remained smooth and intact under a microscope, tightly bonded to the ultra-thin flexible glass, without any cracks or peeling, and the adhesion remained above a 4B level. The printed product showed no abnormalities in performance or appearance after high temperature and humidity (85℃ / 85% RH, 1000h) and thermal shock (-40℃~85℃, 500 cycles) tests. This fully demonstrates the significant technical effect of the present invention in achieving high adhesion and high bending reliability.

[0048] In Example 1, the core functions of each raw material are as follows: The role of acid-resistant epoxy resin: to provide ultra-thin film formation, chemical resistance, and substrate adhesion.

[0049] The function of acid-resistant pigments: to control the color of inks.

[0050] The role of alcohol ether solvents: to adjust the viscosity of ink to 50–150 mPa. s, achieving ultra-thin leveling and precise printing.

[0051] The function of leveling agents: to reduce the surface tension of ink, ensure uniform leveling of ultra-thin ink layers of 0.5-1μm, eliminate pinholes, fisheyes, and pores, improve printing dimensional accuracy, and assist in the formation of a dense and continuous cured film.

[0052] The function of defoamers is to eliminate air bubbles generated during screen printing, prevent pinholes and pores in the ink layer after curing, ensure the density and acid resistance of the ink layer, and help improve the uniformity of ink dispersion.

[0053] The role of the curing agent is to promote ink curing and ensure that the ultra-thin ink layer is completely cured and free of pores.

[0054] Several comparative examples are listed below. The different comparative examples only adjust the proportion of a single raw material, while the other steps and detection methods are exactly the same as in Example 1.

[0055] I. Changes in the dosage of acid-resistant epoxy resin (core film-forming matrix) Comparative Example 1-1: The amount of epoxy resin used was lower (35 parts, the other components were completely the same as in Example 1). Performance test results: Viscosity: 165 mPa s, exceeding 150 mPa s is the upper limit.

[0056] Cured ink layer: average thickness 0.7μm, uniformity ±0.35μm, far exceeding the ±0.1μm requirement, the film layer has a large number of pinholes and discontinuous areas.

[0057] Adhesion: Initial cross-cut adhesion test 3B; after 20,000 bends of R1.5mm, cracks and peeling appear, and the adhesion drops to 1B.

[0058] Core reasons for degradation: Insufficient amount of film-forming substrate cannot form a continuous and dense ultra-thin ink layer. Insufficient pigment carrying capacity leads to agglomeration, and at the same time, the core substrate adhesion is completely lost, failing to meet the core performance requirements of the invention.

[0059] Comparative Examples 1-2: The amount of epoxy resin used was higher (65 parts, the other components were completely consistent with Example 1). Performance test results: Viscosity: 210 mPa s, far exceeding 150 mPa s is the upper limit.

[0060] Cured ink layer: average thickness 1.9μm, exceeding the requirement of ≤1μm, uniformity ±0.42μm, seriously exceeding the standard.

[0061] Adhesion: Initial cross-cut adhesion test 4B; cracks appeared after 80,000 bends with an R1.5mm radius, and the adhesion dropped to 2B after 120,000 bends.

[0062] Core reasons for degradation: Excessive acid-resistant epoxy resin content leads to excessive viscosity, making it impossible to achieve ultra-thin leveling and precise printing. Excessive resin curing results in excessive internal stress, causing ink layer embrittlement and loss of flexibility. At the same time, excessive crosslinking density leads to a significant decrease in bending resistance, making it unsuitable for ultra-thin flexible glass applications.

[0063] II. Changes in the dosage of acid-resistant pigments Comparative Example 2-1: The amount of pigment used was lower (5 parts, the other components were completely consistent with Example 1). Performance test results: Viscosity: 78 mPa s, which meets the viscosity range requirements.

[0064] Cured ink layer: average thickness 0.75μm, uniformity ±0.09μm, meeting the thickness and uniformity requirements.

[0065] Adhesion: Initial cross-cut adhesion test: 5B; adhesion remained at 4B after bending, with no obvious cracks.

[0066] Key defects: severely insufficient tinting strength, poor pattern coverage, and inability to achieve the target color density; severe fading occurs after soaking in 10% hydrochloric acid for 8 hours, and acid resistance stability fails.

[0067] Core reasons for degradation: Insufficient pigment usage fails to meet the coloring requirements of printed markings. At the same time, the overall acid barrier resistance of the ink layer decreases, and the color stability is completely lost after long-term acid immersion, making it impossible to achieve the core function of the invention.

[0068] Comparative Example 2-2: The amount of pigment used was higher (25 parts, and the other components were completely consistent with those in Example 1). Performance test results: Viscosity: 182 mPa s, exceeding 150 mPa s is the upper limit.

[0069] Cured ink layer: average thickness 1.2μm, exceeding the requirement of ≤1μm, uniformity ±0.38μm, seriously exceeding the standard, ink layer has a large number of particle protrusions and pinholes.

[0070] Adhesion: Initial cross-cut adhesion test 3B; after 50,000 bends of R1.5mm, cracks and peeling appear, and the adhesion drops to 1B.

[0071] Acid resistance: After soaking in 10% hydrochloric acid for 4 hours, the acid penetrates along the pigment-resin interface, causing corrosion of the substrate.

[0072] Core reasons for degradation: Excessive pigment cannot be completely encapsulated by the epoxy resin matrix, resulting in agglomeration and sedimentation. This not only damages the rheological properties and leveling effect of the ink, but also creates a large number of stress concentration points and interfacial pores. At the same time, it damages the density of the ink layer, leading to a comprehensive deterioration in adhesion, flexibility, and acid resistance.

[0073] III. Variation in the amount of alcohol and ether solvents used (core components for viscosity and leveling control) Comparative Example 3-1: The amount of solvent used was relatively low (19 parts, the other components were completely consistent with Example 1). Performance test results: Viscosity: 235 mPa s, far exceeding 150 mPa s is the upper limit.

[0074] Cured ink layer: average thickness 1.8μm, far exceeding the requirement of ≤1μm, uniformity ±0.45μm, with orange peel and pinholes appearing.

[0075] Process defects: The solvent evaporates too quickly during the screen printing process, causing screen clogging and poor ink transfer, making it impossible to achieve high-precision printing.

[0076] Adhesion: Initial cross-cut adhesion test: 3B; the adhesion was immediately removed after bending.

[0077] Core reasons for degradation: Insufficient solvent leads to excessively high solid content in the system, causing the viscosity to completely exceed the controllable range, making it impossible to achieve ultra-thin leveling and precise printing. At the same time, the surface drying is too fast during the curing process, resulting in a large number of film defects and the complete failure of core performance.

[0078] Comparative Example 3-2: The amount of solvent used was too high (39 parts, the other components were completely consistent with Example 1). Performance test results: Viscosity: 32 mPa s, below 50 mPa s is the lower limit.

[0079] Cured ink layer: average thickness 0.4μm, unable to reach the minimum film thickness of 0.5μm, resulting in film discontinuity, pinholes, and uniformity ±0.52μm, which seriously exceeds the standard.

[0080] Process defects: Severe ink bleeding and pattern diffusion occur during screen printing, and dimensional accuracy is completely out of control.

[0081] Core reasons for degradation: Excessive solvent leads to a low solid content in the system, resulting in insufficient viscosity and making accurate printing impossible. At the same time, the large amount of solvent evaporates during curing, creating numerous pores that prevent the formation of a continuous and dense ink layer, thus completely losing adhesion.

[0082] IV. Changes in the dosage of leveling agent (core additive for uniformity of ultra-thin ink layers) Comparative Example 4-1: The amount of leveling agent used was lower (0.1 parts, and the other components were completely consistent with those in Example 1). Performance test results: Viscosity: 95 mPa s, which meets the viscosity range requirements.

[0083] Cured ink layer: average thickness 0.8μm, uniformity ±0.41μm, far exceeding the ±0.1μm requirement, with a large number of pinholes, fisheyes and pores.

[0084] Process defects: The edges of the printed pattern are rough, and the dimensional accuracy is seriously exceeded.

[0085] Core reasons for degradation: Insufficient leveling agent leads to excessively high surface tension of the ink, making it impossible to achieve uniform spreading at an ultra-thin thickness of 0.5-1μm, resulting in a large number of film defects, which not only damages the printing accuracy but also completely destroys the density of the ink layer.

[0086] Comparative Example 4-2: The amount of leveling agent used was too high (1.0 part, the other components were completely consistent with Example 1). Performance test results: Viscosity: 90 mPa s, which meets the viscosity range requirements.

[0087] Cured ink layer: average thickness 0.8μm, uniformity ±0.22μm, exceeding the ±0.1μm requirement, resulting in oil spots and pinholes caused by compatibility precipitation.

[0088] Adhesion: Initial cross-cut adhesion test result was 2B; after bending test, it detached directly.

[0089] Core reasons for degradation: Excessive leveling agent reduces the compatibility of the system and creates film defects; at the same time, excessive leveling agent migrates to the ink layer surface to form a weak boundary layer, which seriously damages the adhesion between the ink and the ultra-thin flexible glass, and reduces the density of the ink layer.

[0090] V. Changes in the dosage of defoamer (a core additive for ink layer density) Comparative Example 5-1: The amount of defoamer used was lower (0.1 parts, the other components were completely consistent with Example 1). Performance test results: Viscosity: 94 mPa s, which meets the viscosity range requirements.

[0091] Cured ink layer: average thickness 0.8μm, uniformity ±0.37μm, far exceeding the ±0.1μm requirement, with a large number of pinholes and pores formed by the rupture of air bubbles.

[0092] Dispersibility: The pigments show slight agglomeration, resulting in poor color uniformity.

[0093] Core reasons for degradation: Insufficient defoamer cannot eliminate the air bubbles generated during screen printing. After curing, these bubbles form a large number of penetrating pores, completely destroying the density of the ink layer and affecting the uniformity of ink dispersion and printing accuracy.

[0094] Comparative Example 5-2: The amount of defoamer used was too high (1.0 part, the other components were completely consistent with Example 1). Performance test results: Viscosity: 91 mPa s, which meets the viscosity range requirements.

[0095] Cured ink layer: average thickness 0.8μm, uniformity ±0.28μm, exceeding the ±0.1μm requirement, resulting in craters and oil spots caused by demulsification.

[0096] Adhesion: Initial cross-cut adhesion test result was 3B. After 60,000 bends with a radius of 1.5mm, the adhesion dropped to 1B.

[0097] Core reasons for degradation: Excessive defoamer reduces the compatibility of the system and forms new film defects; at the same time, excessive hydrophobic defoamer will seriously damage the adhesion between the ink layer and the substrate, and will also cause microphase separation, which will damage the density of the ink layer, resulting in a significant decrease in acid resistance and bending durability.

[0098] VI. Changes in curing agent dosage (core components for ink layer curing and cross-linking) Comparative Example 6-1: The amount of curing agent used was lower (2 parts, the other components were completely consistent with Example 1). Performance test results: Viscosity: 93 mPa s, which meets the viscosity range requirements.

[0099] Curing status: The ink layer is not fully cured, the surface is sticky and not dry, and a stable cured film layer cannot be formed.

[0100] Adhesion: Initial cross-cut adhesion test result was 2B; after bending test, it detached directly.

[0101] Core reasons for degradation: Insufficient curing agent content prevents the epoxy resin from fully cross-linking and curing, resulting in extremely low cross-linking density of the ink layer. This leads to a complete loss of density, mechanical strength, and chemical resistance, failing to meet the core usage requirements of the invention.

[0102] Comparative Example 6-2: The amount of curing agent used was too high (8 parts, the other components were completely consistent with Example 1). Performance test results: Viscosity: 90 mPa s, which meets the viscosity range requirements, but has a significantly shortened pot life, causing screen clogging during the screen printing process.

[0103] Cured ink layer: average thickness 0.8μm, uniformity ±0.21μm, exceeding the ±0.1μm requirement, excessive curing shrinkage caused the film layer to curl at the edges.

[0104] Adhesion: Initial cross-cut adhesion test 3B; after 70,000 bends at R1.5mm, cracks and peeling occur, and the adhesion drops to 2B.

[0105] Core reasons for degradation: Excessive curing agent cannot participate in the cross-linking reaction and remains in the ink layer, forming small molecule plasticizers. This leads to increased internal stress and embrittlement of the ink layer. At the same time, excessive curing shrinkage damages adhesion. Residual curing agent will also continue to precipitate, destroying the density of the ink layer and causing a comprehensive deterioration in acid resistance and flexural durability.

[0106] As can be seen from Example 1 and the comparative examples, the dosage range of each component in the formulation of this application is not a conventional choice in the art. The dosage of each component has a strict critical value. If the dosage of a single component deviates, at least one core technical indicator will completely fail, and it will be impossible to achieve multiple performances such as "ultra-thin film formation, high precision uniformity, high adhesion, and high bending durability" at the same time.

[0107] There is a clear synergistic effect among the components. Only within the proportions specified in this application can the technical pain point of existing acid-resistant inks being unable to achieve high-precision printing below 1μm on ultra-thin flexible glass substrates while maintaining excellent acid resistance and bending performance be solved.

[0108] The method provided by this invention can be widely applied to the manufacturing of cutting-edge electronic products such as foldable screen phones, rollable screen TVs, flexible automotive displays, and wearable devices. For example, printing a black border (i.e., printing an ink layer around the perimeter of the UTG cover plate of a foldable screen phone) not only serves to block light and enhance aesthetics, but more importantly, this printed layer must withstand the repeated bending caused by opening and closing the phone. Using the process of this invention can significantly improve the production yield of such products and ensure that they will not experience quality problems such as ink cracking or peeling during their service life, thus significantly improving the reliability of the final product.

[0109] This embodiment also discloses a UTG protective film, such as Figure 2 As shown, a UTG protective film includes: The ultrathin flexible glass layer 1 has a first surface and a second surface, and the thickness of the ultrathin flexible glass layer is 30μm-100μm; Ink layer 2, located at the periphery of the second surface of the ultrathin flexible glass layer, has a thickness of 0.5 μm–1 μm and the formulation of the ink layer is as described above; and Adhesive layer 3 is located on the second surface of the ultrathin flexible glass layer and the outer surface of the ink layer, and the thickness of adhesive layer 3 is 30um-50um.

[0110] In a preferred embodiment, a functional layer (not shown in the figure) located on the first surface of the ultrathin flexible glass layer is further included. The functional layer can be formed by multiple layers, such as an oleophobic layer. In practical applications, the functional layer can be an oleophobic layer or a combination of multiple layers, and the adhesive layer can be AB adhesive or UV adhesive suitable for ultrathin flexible glass layers.

[0111] The above description is merely a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any equivalent structural transformations made based on the description and drawings of the present invention, whether directly or indirectly applied to other related technical fields, are similarly included within the scope of protection of the present invention.

Claims

1. A screen printing method suitable for UTG, characterized in that, Includes the following steps: S1. Perform surface cleanliness treatment on ultra-thin flexible glass; S2. Print an ink layer around the periphery of the ultra-thin flexible glass layer to be printed, the ink layer being formed of an ink comprising the following components in parts by weight: Acid-resistant epoxy resin: 48-52 parts; Acid-resistant pigment: 13-17 parts; Alcohol ether solvents: 27-31 parts; Leveling agent: 0.4-0.6 parts; Defoamer: 0.4-0.6 parts; Hardener: 4-6 parts; S3. The ultra-thin flexible glass printed with the ink is cured at a temperature of 80℃-110℃. After curing, the thickness of the ink layer is 0.5μm-1μm.

2. The screen printing method for UTG as described in claim 1, characterized in that, The acid-resistant epoxy resin is a bisphenol A type epoxy resin, which is prepared by reacting bisphenol A with epichlorohydrin, and the mass ratio of bisphenol A to epichlorohydrin is 1:(2.8-4.7). The acid-resistant pigment is carbon black, ultramarine, or phthalocyanine blue. The alcohol ether solvent is at least one of diethylene glycol butyl ether, propylene glycol methyl ether, and propylene glycol methyl ether acetate.

3. The screen printing method for UTG as described in claim 1, characterized in that, The leveling agent is a siloxane; The defoamer is at least one of modified silicone oil and hydrophobic silica; The curing agent is at least one of modified phosphoric acid, salicylic acid, and benzoic acid.

4. The screen printing method for UTG as described in claim 1, characterized in that, In step S2, a non-contact suction platform is used to adsorb and fix the ultra-thin flexible glass, and then ink is printed on the ultra-thin flexible glass using a wire mesh. The printing pressure of the wire mesh is 8 N / cm²–15 N / cm².

5. The screen printing method for UTG as described in claim 4, characterized in that, The wire mesh is a 500-640 mesh wire mesh, and the tension of the wire mesh is 21N / cm-25N / cm.

6. The screen printing method for UTG as described in claim 1, characterized in that, In step S3, the heat preservation time for curing is 5-10 minutes.

7. The screen printing method for UTG as described in claim 1, characterized in that, In step S3, the curing temperature is 100℃ and the holding time is 10 minutes.

8. The screen printing method for UTG as described in claim 1, characterized in that, In step S1, the surface cleanliness treatment step includes: The ultrathin flexible glass is ultrasonically cleaned using an alkaline cleaning agent, wherein the concentration of the alkaline cleaning agent is 1%±0.2%, the cleaning temperature is 50℃±5℃, and the treatment time is 150s-210s.

9. A UTG protective film, characterized in that, include: An ultra-thin flexible glass layer having a first surface and a second surface, wherein the thickness of the ultra-thin flexible glass layer is 30μm-100μm; An ink layer is located at the periphery of the second surface of the ultrathin flexible glass layer, and the thickness of the ink layer is 0.5μm–1μm; as well as An adhesive layer is located on the second surface of the ultrathin flexible glass layer and the outer surface of the ink layer; The ink layer is formed from an ink comprising the following components in parts by weight: Acid-resistant epoxy resin: 48-52 parts; Acid-resistant pigment: 13-17 parts; Alcohol ether solvents: 27-31 parts; Leveling agent: 0.4-0.6 parts; Defoamer: 0.4-0.6 parts; Hardener: 4-6 parts.

10. The UTG protective film as described in claim 9, characterized in that, It also includes a functional layer located on the first surface of the ultrathin flexible glass layer.

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