Multi-purpose high-viscosity replicable glass film and preparation method thereof

Abstract

The invention relates to the technical field of processing and manufacturing of glass decorative protective films, and discloses a multipurpose high-viscosity replicable glass film and a preparation method thereof. Comprising the following steps: by taking a flexible polymer film as a base material, performing corona treatment with specific parameters to form an activated surface, coating an ink-jet printing layer containing inorganic nano silicon dioxide, and drying; then preparing an embossed polyethylene release film, coating a waterborne hot melt adhesive in a dotted manner to form a bonding layer, performing hot-pressing compounding on the base material and the release film, and performing post-curing, curing and slitting to obtain a finished product. Through refined process parameter control and optimization of the surface activity of the base material and the adhesive layer structure, the product has high viscosity and recoverability, is bubble-free in lamination, easy to construct, firm in printing layer adhesion, clear in pattern, weather-proof and environment-friendly, meets the requirements of multi-scene glass films, is stable in process and is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of glass decorative protective film processing and manufacturing technology, specifically to a multi-purpose high-adhesion re-adhesive glass film and its preparation method. Background Technology

[0002] With the rapid development of architectural decoration, automotive interiors, and commercial displays, glass surface films have become a commonly used material that combines decoration, protection, and functionality. Market demand continues to rise, and application scenarios are gradually expanding from simple glass protection to diverse areas such as personalized pattern decoration, privacy shading, and light adjustment. Currently, most conventional glass films on the market suffer from insufficient performance adaptability, high installation difficulty, and poor reusability, making it difficult to meet the current market demands for refined installation, multi-scenario reuse, and long-term stable use. Conventional films often use ordinary flexible films as the substrate, without surface activation treatment. The surface is smooth and has low surface tension, resulting in weak adhesion between the coating and the substrate during subsequent spraying or printing. Over long-term use, this leads to problems such as coating peeling, flaking, pattern blurring, and cracking, directly affecting the film's appearance integrity and lifespan. Furthermore, they are not compatible with high-precision inkjet printing processes, making it difficult to achieve high-definition, detailed pattern printing, thus limiting the product's application in high-end decorative scenarios.

[0003] In terms of adhesive layer design, existing glass films mostly adopt a continuous, full-coat adhesive layer structure, resulting in poor uniformity of adhesive layer distribution. When applied to the glass surface, air is difficult to expel quickly, easily leaving air bubbles. The application process requires repeated scraping and adjustment, which is not only time-consuming and labor-intensive but also prone to wrinkling and deformation due to uneven scraping pressure. If misaligned, peeling and reapplying can easily damage the adhesive layer, causing a sharp drop in adhesion and preventing smooth re-application. Some films even leave large amounts of adhesive residue on the glass surface, making cleaning extremely difficult and damaging the glass's surface smoothness. Furthermore, conventional films often use oil-based adhesives, which are not environmentally friendly and easily release harmful substances under high temperatures. They also lack weather resistance; long-term exposure to light and temperature changes causes the adhesive layer to age and yellow, gradually weakening its adhesion and leading to edge lifting and film detachment. This results in poor adhesion stability to glass surfaces and makes them unsuitable for long-term use under varying temperature and humidity conditions.

[0004] From a manufacturing process perspective, the current window film production process suffers from relatively loose control over process parameters in steps such as substrate pretreatment, coating application, lamination molding, and curing. Key processes like corona treatment, coating drying, and hot-press lamination lack refined management, easily leading to problems such as uneven film thickness, loose interlayer bonding, and poor dimensional stability. This results in a low finished product qualification rate after slitting, making it difficult to guarantee consistent product performance in mass production. Furthermore, conventional window films often have a planar release layer without targeted embossing design, making them prone to sticking to the adhesive layer during peeling. This not only affects peeling smoothness but also damages the original adhesive layer structure, further reducing re-lamination performance. Currently, the market lacks a multi-purpose window film that combines high adhesion, re-lamination capability, ease of application, high-definition printing compatibility, and environmental friendliness and weather resistance. Corresponding systematic manufacturing processes also have significant shortcomings, failing to balance production stability and overall product performance, making it difficult to meet the current diverse and high-quality window film application demands. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-purpose, high-adhesion, re-adhesive glass film and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides a multi-purpose, high-adhesion, re-adhesive glass film and a method for preparing the same, the method comprising: Step a: Select a flexible polymer film with a thickness of 25μm to 100μm as the substrate layer, place it in a clean room, and treat one surface of the film with an online corona treatment machine at a power of 1.5kW to 2.5kW and a speed of 10m / min to 20m / min to increase its surface tension to more than 50dyn / cm, forming an activated surface for coating the inkjet printing layer; Step b: Prepare the inkjet printing layer coating solution, which contains 5% to 8% inorganic nano-silica, 2% to 4% polyvinylpyrrolidone, 0.1% to 0.3% leveling agent, and deionized water by mass fraction; place the substrate layer obtained in step a on the unwinding end of a precision coating machine with the activated surface facing upwards, and apply the coating solution evenly to the activated surface using a microgravure coating method under the conditions of temperature 20°C to 25°C and humidity 45% to 55%, with a wet film coating thickness of 10μm to 15μm; immediately after coating, introduce the substrate layer into an oven at a temperature of 80°C to 100°C for drying for 1 to 2 minutes, finally forming an inkjet printing layer with a dry film thickness of 5μm to 8μm; Step c: The substrate layer with inkjet printing layer after step b is introduced into the preheating area. The preheating temperature is set to 50°C to 60°C. The winding and unwinding tension is adjusted to keep the substrate layer flat and wrinkle-free before entering the lamination process. The winding tension is controlled between 1.5 kgf and 2.5 kgf. Step d: Select low-density polyethylene masterbatch with a thickness of 30μm to 80μm, and prepare a release film substrate through a casting process. While the casting temperature is between 150℃ and 180℃, immediately press the film surface with an embossing roller bearing a small dot pattern to form embossed units with a diameter of 0.5mm, thus obtaining a polyethylene embossed release film. On the embossed surface of the polyethylene embossed release film, apply water-based hot melt adhesive using an anilox roller coating device at a coating temperature of 2... The viscosity of the water-based hot melt adhesive is 1500 cps to 2500 cps at a temperature of 5°C to 30°C. The line count of the anilox roller is set to 150 lines per inch, and the coating speed is controlled at 15 m / min to 25 m / min. This allows the adhesive to form a matrix dotted structure on the release film surface that matches the embossing. The film is then cured in an oven at a temperature of 90°C to 110°C for 1.5 minutes to 3 minutes, forming a bonding layer with a dry adhesive thickness of 5 μm to 20 μm. Step e: With the side with the inkjet printing layer facing outwards, place the preheated substrate layer obtained in step c into a roller laminating machine with the other side facing the cured adhesive layer on the polyethylene embossed release film obtained in step d. The roller laminating machine is then used for hot pressing. The temperature of the hot pressing roller is set to 70°C to 80°C, the linear pressure is set to 3 kgf / cm to 5 kgf / cm, and the laminating linear speed is consistent with the coating speed in step d. Step f: The semi-finished product after step e is placed in a post-curing zone at a temperature of 45℃ to 55℃ and cured for 24 to 48 hours to form a stable interface bond between the bonding layer and the inner surface of the substrate layer. After curing, the wide roll material is cut into the width specifications required by the customer by a slitting machine and wound up in a constant temperature and humidity environment with the winding tension controlled at 1.0 kgf to 1.5 kgf to obtain the finished roll material.

[0007] Preferably, the online corona treatment machine in step a adopts a dual-electrode structure with an electrode spacing of 1.2 mm and a processing frequency of 20 kHz, ensuring that a uniform micro-roughening structure can be formed on the surface of the substrate film during the treatment process.

[0008] Preferably, the inorganic nano-silica in step b has a particle size range of 20nm to 50nm. When preparing the coating solution, the inorganic nano-silica is first uniformly dispersed in deionized water under ultrasonic action for 30 minutes at a power of 500W. Then, polyvinylpyrrolidone and leveling agent are added, and the mixture is stirred at 300rpm for 2 hours at room temperature to form a uniform and stable coating solution suspension system.

[0009] Preferably, the specific process parameters for the microgravure coating method in step b are as follows: using a gravure roller with a screen count of 200 lines / inch, a doctor blade pressure of 0.2 MPa, a coating angle of 30 degrees, and a coating gap of 0.1 mm to ensure uniform wet film thickness and control the coating CV value within 3%.

[0010] Preferably, the specific operation of the anilox roller coating equipment in step d includes: immersing the anilox roller coated with adhesive into the adhesive storage tank, controlling the amount of adhesive transferred to the roller surface by a metering scraper, and then transferring the adhesive to the embossed surface of the polyethylene embossed release film running at a constant speed by roller-to-roll. During the transfer process, the running tension of the release film is controlled to be 1.0 kgf to 1.2 kgf.

[0011] Preferably, the composition of the water-based hot melt adhesive in step d is as follows: by mass, it comprises 35 to 45 parts of ethylene-vinyl acetate copolymer emulsion, 20 to 30 parts of acrylic pressure-sensitive adhesive emulsion, 5 to 10 parts of hydrogenated rosin glycerol ester, 1 to 3 parts of polyethylene glycol, and 0.5 to 1 part of polyether-modified polysiloxane defoamer.

[0012] Preferably, the composite roller of the roller laminating machine in step e is a silicone-coated roller with a Shore A hardness of 60 to 70 degrees. During lamination, the gap between the two rollers is controlled to be 1.1 to 1.2 times the total thickness of the substrate layer, the bonding layer and the release film layer.

[0013] Preferably, between step e and step f, there is also step e1: preliminary cooling and shaping, in which the composite semi-finished product is immediately introduced into a cooling roller group with a temperature of 15°C to 20°C, the surface temperature of the cooling roller is 10°C to 15°C, and the cooling time is 5 seconds to 10 seconds, so that the composite structure is initially shaped and interlayer displacement is prevented due to thermal stress.

[0014] Preferably, the control conditions of the constant temperature and humidity environment in step f are: temperature 23℃±2℃, relative humidity 50%±5%, the rotation speed of the circular blade of the slitting machine is 500rpm to 800rpm, and the width of the burrs produced during slitting is less than 0.2mm.

[0015] Preferably, the present invention also includes a multi-purpose high-adhesion re-adhesive glass film prepared according to the above preparation method, characterized in that it comprises, from the outside to the inside, an inkjet printing layer, a substrate layer, an adhesive layer, and a release film layer; the inkjet printing layer is a surface that has been corona treated and coated with a mixed coating of inorganic nano-silica and polyvinylpyrrolidone; the substrate layer is a nylon film or polyethylene terephthalate film that has been preheated and tension controlled; the adhesive layer is a water-based hot melt adhesive layer coated on the embossed surface of a polyethylene embossed release film by an anilox roller, and its morphology is a matrix dot structure; the release film layer is a polyethylene embossed release film with micro-dot embossed units on the surface with a diameter of 0.5 mm.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention, through a multi-stage refined manufacturing process, produces a versatile, high-adhesion, re-adhesive glass film with superior overall performance. It comprehensively optimizes product performance and production adaptability, overcoming many limitations of existing similar products. After online corona treatment with specific parameters, the substrate layer forms a uniform micro-roughened activated structure on its surface, achieving stable surface tension and significantly optimizing surface adhesion. Following inkjet printing, a tight, interlocking bond is formed between the coating and the substrate, effectively preventing coating peeling and pattern cracking. It is also compatible with high-precision inkjet printing, clearly reproducing various high-definition patterns with uniform and durable color adhesion, balancing decorative and practical applications and broadening the product's application range in high-end decoration and commercial displays. The inkjet printing coating solution uses a compound system of inorganic nano-silica and polyvinylpyrrolidone, combined with a refined ultrasonic dispersion and stirring process. This results in a uniform and delicate coating texture with controllable and consistent dry film thickness. It possesses excellent printing adaptability and enhances the wear resistance of the film surface, reducing scratch damage during daily use and extending the overall product lifespan.

[0017] The bonding layer utilizes a dot-matrix structure design of water-based hot melt adhesive, working in conjunction with an embossed release film. This completely overcomes the drawbacks of conventional continuous adhesive layers. When the adhesive layer adheres to the glass surface, the embossed gaps form natural air vents, allowing air to escape quickly and smoothly. This eliminates the need for repeated scraping and pressing, achieving bubble-free bonding and significantly reducing construction difficulty. Even if misalignment occurs, it can be easily peeled off and reapplied. During re-application, the adhesive layer structure remains intact, with no significant decrease in adhesion. After peeling, no adhesive residue remains on the glass surface, perfectly preserving the original smoothness of the glass. The water-based hot melt adhesive uses environmentally friendly compounded components, free of oily and harmful substances. It exhibits stable performance at both room and high temperatures, releases no odor, and is suitable for various indoor and outdoor applications. It boasts excellent weather resistance, resisting long-term exposure to light, temperature, and humidity fluctuations without aging or yellowing. It maintains stable adhesion, bonding tightly to the glass surface and preventing edge lifting or detachment, thus meeting the long-term usage needs in different environments.

[0018] Every step of the production process is precisely controlled, with precise temperature, speed, pressure, and tension parameters set for each stage, including corona treatment, coating and drying, preheating and lamination, and curing. Combined with specialized processes such as micro-gravure coating, anilox roller dot coating, and roller hot-press lamination, this ensures uniform thickness of each film layer, tight interlayer bonding, and no delamination, wrinkles, or uneven thickness. After post-curing, the semi-finished product exhibits stable interlayer bonding, excellent dimensional consistency, and a high yield rate after slitting, making it suitable for large-scale continuous production. The embossed release film is prepared using a specific casting embossing process, resulting in regular and uniform embossed units that peel off smoothly without sticking. This effectively protects the adhesive surface of the bonding layer from contamination and damage, while simplifying the application process. No additional auxiliary tools are required during application, making it suitable for various application scenarios and personnel. Attached Figure Description

[0019] Figure 1 This diagram illustrates the working steps of a method for preparing a multi-purpose, high-adhesion, re-adhesive glass film according to the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Other embodiments obtained by those skilled in the art based on the core process concept of the present invention without creative effort are all within the scope of protection of the present invention. This specific embodiment only discloses the complete implementation steps, process parameters, comparative ratio settings, and performance verification content of the preparation method. All raw materials and equipment are commercially available conventional products, the operating environment meets the Class 10,000 cleanroom standard, and the performance testing methods adopt industry-standard practices.

[0021] Raw material and equipment preparation 1. Raw material specifications Flexible polymer substrate layer: PET polyester film, thickness range 25μm-100μm, light transmittance ≥90%, tensile strength ≥150MPa, commercially available conventional optical grade film; Inorganic nano-silica: particle size 20nm-50nm, purity ≥99.5%, free of agglomerated particles; Polyvinylpyrrolidone: molecular weight 10000, industrial grade pure product; Leveling agent: polyether-modified organosilicon leveling agent, solvent-free; Low-density polyethylene masterbatch: melt index... 5g / 10min, food contact grade; Ethylene-vinyl acetate copolymer emulsion: 50% solids content, 28% vinyl acetate content; Acrylic ester pressure-sensitive adhesive emulsion: 55% solids content, glass transition temperature -40℃; Hydrogenated rosin glycerol ester: softening point 85℃, tackifying resin; Polyethylene glycol: molecular weight 400; Polyether-modified polysiloxane defoamer: 100% solids content; Other auxiliary materials for water-based hot melt adhesive are deionized water and pH adjuster (ammonia, concentration 5%).

[0022] 2. Equipment parameters Online corona treatment machine: dual-electrode structure, adjustable power 0-5kW, adjustable frequency 0-50kHz, adjustable electrode spacing; Precision microgravure coating machine: equipped with a 200 lines / inch microgravure roller, adjustable doctor blade pressure 0-1MPa, adjustable coating angle 0-90°; Drying tunnel: segmented temperature control, accuracy ±1℃; Cast film forming machine: temperature range 100℃-250℃ adjustable, embossing roller with customized 0.5mm diameter dot matrix pattern; Anilox roller coating machine: 150 lines / inch anilox roller, metering doctor blade accuracy 0.01mm; Double roller laminating machine: silicone-coated composite roller, adjustable Shore hardness, adjustable linear pressure 0-10kgf / cm; Post-curing and ripening chamber: constant temperature and humidity control, accuracy ±1℃, ±3%; Slitting machine: circular blade speed adjustable 0-1000rpm, closed-loop control of winding and unwinding tension.

[0023] 3. Performance Testing Standards Surface tension: Tested using a dyne pen, accuracy ±1 dyn / cm; Initial adhesion: Tested using a 180° peel strength test, with a 5mm float glass substrate at a speed of 300mm / min, unit N / 25mm; Re-adhesion performance: After repeated pasting 5 times, the peel strength retention rate was tested, and the presence of residual adhesive, bubbles, and lifting was observed; Dry film thickness: Tested using a micrometer thickness gauge, accuracy ±0.1μm; Coating uniformity: CV value (coefficient of variation), calculated from 10 randomly selected measuring points; Temperature resistance: Placed at 60℃ for 24 hours, the interlayer separation and adhesive migration were observed; Burr width: Tested under a microscope after slitting, accuracy ±0.01mm.

[0024] Example 1: Preparation of baseline process parameters See appendix Figure 1 This invention provides a method for preparing a multi-purpose, high-adhesion, re-adhesive glass film, the steps of which are as follows: Step a: Substrate corona activation treatment A 50μm thick PET flexible polymer film was selected as the substrate layer and placed in a Class 10,000 cleanroom at a temperature of 23℃ and a relative humidity of 50%. An online corona treatment machine was turned on, employing a dual-electrode structure with an electrode spacing of 1.2mm, a treatment frequency of 20kHz, a treatment power of 2.0kW, and a treatment speed of 15m / min. The film was continuously treated on one side. After treatment, the surface tension was tested using a dyne pen to ensure that the surface tension was stable at 55dyn / cm, forming a uniformly micro-roughened activated surface for later use. Throughout the process, dust and oil contamination on the substrate surface were avoided. The next coating process was carried out within 30 minutes after corona treatment to prevent surface energy decay.

[0025] Step b: Inkjet printing layer coating and drying Preparation of inkjet printing coating solution: Weigh 6.5% inorganic nano silica (particle size 35nm), 3% polyvinylpyrrolidone, and 0.2% polyether-modified silicone leveling agent by mass fraction, with the remainder being deionized water; during preparation, first add the inorganic nano silica to the deionized water, turn on the ultrasonic disperser at 500W, and ultrasonically disperse for 30 minutes to completely break up particle agglomeration and form a uniform dispersion; then add the polyvinylpyrrolidone and leveling agent, turn on the magnetic stirrer at 300rpm, and stir at room temperature for 2 hours to obtain a stable coating solution suspension system without precipitation or stratification.

[0026] The activated substrate layer from step a is loaded into the unwinding end of a precision coating machine with the activated surface facing upwards. The ambient temperature is adjusted to 23°C and the relative humidity to 50%. A microgravure coating method is used, with a microgravure roller screen count of 200 lines / inch, a doctor blade pressure of 0.2 MPa, a coating angle of 30°, and a coating gap of 0.1 mm. The wet film coating thickness is controlled at 12 μm. After coating, the substrate is immediately introduced into a segmented drying tunnel. The tunnel temperatures are set sequentially to 85°C, 90°C, and 95°C, with a total drying time of 1.5 minutes. After drying, the substrate is allowed to cool naturally to room temperature, forming an inkjet printing layer with a dry film thickness of 6.5 μm. The coating CV value is 2.2%, which meets the uniformity requirements.

[0027] Step c: Substrate preheating and tension adjustment The substrate layer with the inkjet printing layer is introduced into the preheating zone. The preheating temperature is set to 55℃ and the preheating time is 30 seconds. Simultaneously, the unwinding and winding tensions are adjusted, with an unwinding tension of 1.8 kgf and a winding tension of 2.0 kgf, to ensure that the substrate layer is flat, wrinkle-free, and free from stretching deformation throughout the process. After preheating, the lamination process is started immediately to avoid substrate temperature fluctuations affecting the lamination effect.

[0028] Step d: Preparation of embossed release film and coating and curing of bonding layer Low-density polyethylene masterbatch with a thickness of 50μm was selected, and release film substrate was prepared by casting process. The casting temperature was set to 165℃. After the melt was extruded, it was immediately hot-pressed by a customized embossing roller. The embossing roller has uniform dot embossing units with a diameter of 0.5mm. The pressing pressure is 0.3MPa, and the pressing speed is the same as the casting speed. The polyethylene embossed release film was obtained with uniform embossing depth and no missing embossing or continuous embossing.

[0029] Preparation of water-based hot melt adhesive: Weigh 40 parts by weight of ethylene-vinyl acetate copolymer emulsion, 25 parts by weight of acrylic pressure-sensitive adhesive emulsion, 8 parts by weight of hydrogenated rosin glycerol ester, 2 parts by weight of polyethylene glycol 400, 0.8 parts by weight of polyether modified polysiloxane defoamer, and the remainder is deionized water. Stir and mix evenly, adjust the viscosity to 2000 cps, and apply at 28℃.

[0030] A 150 lines / inch anilox roller coating system is used. Water-based hot melt adhesive is added to the storage tank, and the anilox roller is immersed in the adhesive solution. The amount of adhesive transferred is controlled by a metering doctor blade. The release film running tension is 1.1 kgf, and the coating speed is 20 m / min. The adhesive solution is evenly coated on the embossed surface of the embossed release film to form a matrix dotted adhesive layer structure that matches the dot embossing. After coating, the film is immediately placed in an oven for curing. The oven temperatures are 95℃, 100℃, and 105℃, and the total curing time is 2 minutes. After curing, a bonding layer with a dry adhesive thickness of 12 μm is formed. The adhesive layer is free of bubbles, missed coatings, and sagging.

[0031] Step e: Hot pressing composite The preheated substrate layer and the embossed release film are precisely aligned, with the inkjet-printed side of the substrate layer facing outwards and the non-printed side facing the adhesive side of the bonding layer. They are then simultaneously fed into a roller laminator. The laminator rollers are silicone-coated rollers with a Shore A hardness of 65 degrees, a temperature of 75℃, a linear pressure of 4 kgf / cm, and a lamination linear speed of 20 m / min, consistent with the coating speed of the bonding layer. The lamination gap is set to 1.15 times the total thickness of the substrate layer, inkjet-printed layer, bonding layer, and release film to ensure complete adhesion between layers without bubbles or misalignment.

[0032] Step e1: Preliminary cooling and shaping The composite semi-finished product is immediately introduced into the cooling roller assembly. The surface temperature of the cooling roller is 12℃, the ambient temperature is 18℃, and the cooling time is 8 seconds. This rapidly reduces the temperature of the composite layer, eliminates thermal stress, prevents interlayer displacement and wrinkling, and completes the initial shaping.

[0033] Step f: Post-curing and finishing, and slitting of finished products After cooling and shaping, the semi-finished product is sent to a curing chamber at 50℃ for 36 hours to form a stable interface between the bonding layer and the non-printed surface of the substrate layer, eliminating internal stress. After curing, it is transferred to the slitting process. The slitting environment is constant temperature and humidity: temperature 23℃±2℃, relative humidity 50%±5%, rotary blade speed 650rpm, slitting width set according to customer requirements, controlling the burr width to be less than 0.2mm, and winding tension 1.2kgf. After winding, it is sealed and packaged to obtain the finished glass film.

[0034] Example 2: Optimized Process for Low-Thickness Substrates This embodiment is designed for ultra-thin substrate scenarios. The substrate thickness, corona parameters, and coating parameters are adjusted, while the remaining steps are the same as in Embodiment 1. The core parameters are adjusted as follows: Step a: Select a 25μm ultrathin PET film, apply corona treatment power of 1.5kW, process speed of 10m / min, and control the surface tension at 52dyn / cm to avoid film breakdown due to excessive power; Step b: Use 5% inorganic nano-silica by mass, wet film coating thickness of 10μm, drying temperature of 80℃, drying time of 1 minute, and dry film thickness of 5μm to prevent the ultrathin substrate from deforming due to heat; Step d: Release film thickness of 30μm, casting temperature of 150℃, water-based hot melt adhesive viscosity of 1500cps, coating speed of 15m / min, and dry adhesive thickness of 5μm; Step e: Composite linear pressure of 3kgf / cm, composite temperature of 70℃; Step f: Curing time of 24 hours. The remaining process parameters and operating steps are exactly the same as in Example 1, and the final product is completed.

[0035] Example 3: Optimized process for high-viscosity thick adhesive layers This embodiment addresses scenarios requiring high adhesion and high bonding strength by increasing the adhesive layer thickness, tackifying resin content, and lamination pressure. The remaining steps are the same as in Embodiment 1, with the core parameters adjusted as follows: Step a: Select a 100μm thick PET film, apply corona treatment with a power of 2.5kW, a processing speed of 20m / min, and control the surface tension at 60dyn / cm to improve interfacial adhesion; Step b: Use 8% inorganic nano-silica by mass, apply a wet film coating with a thickness of 15μm, dry at 100℃ for 2 minutes, and achieve a dry film thickness of 8μm; Step d: Use a release film with a thickness of 80μm, a casting temperature of 180℃, and an aqueous hot melt adhesive with 10 parts by mass of hydrogenated rosin glycerol ester, a viscosity of 2500cps, a coating speed of 25m / min, and a dry adhesive thickness of 20μm; Step e: Use a lamination line pressure of 5kgf / cm and a lamination temperature of 80℃; Step f: Use a curing time of 48 hours. All other process parameters and operating steps are exactly the same as in Example 1, and the final product is completed.

[0036] Comparative Example 1: Corona-free activation treatment In this comparative example, step a, the corona activation process, was removed. A 50μm untreated PET film was used directly as the substrate layer. The remaining process parameters, raw material ratios, and operating steps were completely consistent with those in Example 1. That is, the corona treatment of the substrate surface was skipped, and the inkjet printing layer was directly coated. The subsequent preheating, lamination, curing, and slitting steps were not adjusted to prepare the comparative sample.

[0037] Comparative Example 2: Conventional planar release film + continuous adhesive layer In step d of this comparative example, the embossed release film preparation process was omitted, and a common flat low-density polyethylene release film was used without the 0.5mm dot embossing structure. At the same time, the water-based hot melt adhesive was applied in a continuous topcoat method instead of a matrix dot coating. The coating thickness, adhesive ratio, and curing parameters were the same as in Example 1. The process parameters of the remaining steps a, b, c, e, and f were exactly the same as in Example 1, and a comparative sample was prepared.

[0038] Comparative Example 3: No post-curing or ripening process This comparative example omits step f, the curing and maturation process, and directly proceeds to slitting and winding after composite cooling and shaping. The remaining process parameters, raw material ratios, and operating steps are completely consistent with those of Example 1. That is, after composite cooling, the 36-hour curing at 50°C is skipped, and the slitting process is directly initiated. The winding tension and slitting parameters remain unchanged, and a comparative sample is prepared.

[0039] Table 1: Comparison of core process parameters between the examples and comparative examples

[0040] Table 1 clearly compares the core process differences between the three sets of examples and the three pairs of comparative examples. Examples 1-3 fully retain all the core processes of this invention, only optimizing parameters such as substrate thickness, corona power, coating speed, and adhesive layer thickness, covering thin, medium, and thick substrates and low, medium, and high viscosity requirements to suit different application scenarios. Comparative examples 1-3, on the other hand, each omit one core process, while the remaining parameters are completely consistent with the baseline example 1, which can accurately verify the impact of a single process variable on product performance. Among them, corona treatment, embossed release film + dotted adhesive layer, and post-curing are the three core processes of this invention. The comparative examples each omit one of them, which can intuitively reflect the necessity of the core processes.

[0041] Table 2: Basic Performance Test Results of Examples and Comparative Examples

[0042] After corona treatment, the surface tension of Examples 1-3 all reached above 50 dyn / cm, the coating CV value was below 3%, and the inkjet printed layer was uniformly adhered without any missed coating or uneven thickness. In contrast, Comparative Example 1 was not corona treated, and the surface tension of the substrate was only 38 dyn / cm, far below the standard value. The low surface energy resulted in poor wetting effect of the coating liquid, and the coating CV value rose to 5.6%, with a significant decrease in uniformity. This directly affected the subsequent inkjet printing effect and interlayer adhesion, proving that the corona activation process is the core prerequisite for improving the surface energy of the substrate and ensuring coating uniformity.

[0043] Example 1 exhibits moderate peel strength, suitable for typical scenarios; Example 2, due to its ultra-thin substrate and thin adhesive layer, shows slightly reduced peel strength, but still meets usage requirements; Example 3, by increasing the tackifying resin content and adhesive layer thickness, achieves a peel strength of 16.2 N / 25 mm, meeting high adhesion requirements; Comparative Example 1, due to poor surface adhesion, has a peel strength of only 4.2 N / 25 mm, failing to meet the requirements for glass film bonding; Comparative Example 2, using a planar release film and continuous adhesive layer, has an initial strength slightly lower than Example 1, mainly due to poor air release properties of the continuous adhesive layer, resulting in insufficient bonding area due to residual air bubbles during bonding; Comparative Example 3, without post-curing, has incompletely stable interface bonding, with an initial strength of only 8.7 N / 25 mm, far lower than the baseline example.

[0044] All three sets of examples underwent post-curing and curing, exhibiting stable interlayer bonding, no abnormalities in the 60℃ high-temperature resistance test, and slit burr widths of less than 0.2mm, meeting the precision requirements of the finished product. Comparative Example 1 showed insufficient interlayer bonding, resulting in layer separation and adhesive migration at high temperatures. Comparative Example 2 showed continuous adhesive layers without dot-like buffer structures, leading to adhesive overflow at high temperatures. Comparative Example 3 lacked curing, internal stress was not eliminated, interlayer bonding was extremely unstable, large-area separation occurred at high temperatures, and burr widths exceeded standards during slitting due to unstable substrate tension. This demonstrates that post-curing and curing is a key process for improving product stability, high-temperature resistance, and slitting quality.

[0045] Table 3: Comparison of Re-adhesive Performance between Examples and Comparative Examples

[0046] The re-adhesive performance is the core innovative feature of this invention. The table data intuitively demonstrates the decisive role of the core process in the re-adhesive effect, as analyzed in detail below: Re-application times and strength retention: The three sets of examples, with their embossed release film and matrix dotted adhesive layer structure, all achieved a re-application time far exceeding that of conventional glass films. After 5 re-applications, the peel strength retention rate was higher than 88%. Among them, Example 3, due to its high adhesive layer thickness and stable interface bonding, achieved a strength retention rate of 94.1% and could be re-application more than 12 times, fully meeting the needs of repeated pasting in multiple scenarios. Example 2, due to its thinner substrate, had a slightly lower re-application time, but it still met the requirements for daily use, proving that the present invention can achieve excellent re-application performance within the adjustable range of parameters.

[0047] Residual Adhesive and Bubble Control: In Examples 1-3, there was no residual adhesive, no bubbles, and no peeling after lamination. The core reason is that the dotted adhesive layer structure can achieve rapid air venting, avoiding bubble residue when continuous adhesive layers are laminated. At the same time, the corona treatment and post-curing process ensure that the adhesive layer is firmly bonded to the substrate, and there is no adhesive residue or transfer when peeling off. In Comparative Example 1, due to poor interlayer bonding, a large amount of adhesive layer remained on the glass surface during lamination, and the poor wetting of the substrate prevented the bubbles from being expelled. It completely failed after two laminations. Comparative Example 2 used a continuous adhesive layer with extremely poor air venting performance. It was difficult to expel bubbles during lamination, and residual adhesive and peeling appeared after lamination. It could only be laminated three times. Comparative Example 3 did not have post-curing, and the internal stress of the adhesive layer was not eliminated. The adhesive layer was easy to fall off during lamination, and obvious residual adhesive and peeling appeared. The strength retention rate was only 52.4%, and stable lamination could not be achieved.

[0048] Synergistic effect of core processes: Corona treatment enhances the adhesion between the substrate and the adhesive layer and prevents adhesive residue; embossed dotted adhesive layer improves air release performance and avoids bubble formation; post-curing stabilizes the interface bonding and eliminates internal stress. The three processes work together to achieve the core effect of high adhesion and re-lamination. The comparison shows that the absence of any one process will lead to a significant decrease in re-lamination performance, proving that the process steps of this invention are indispensable and the overall synergistic effect is far superior to single process optimization.

[0049] The three embodiments provided by this invention, through precise control of the entire process parameters such as corona activation, inkjet printing layer coating, embossed release film preparation, dot adhesive layer coating, hot pressing lamination, and post-curing, produce a multi-purpose high-adhesion re-adhesive glass film that combines high initial adhesion, excellent re-adhesive performance, good coating uniformity, and high-temperature stability. It can be adapted to various application scenarios such as ultra-thin substrates, conventional substrates, and high-adhesion requirements, fully meeting the multi-scenario use needs of glass films.

[0050] After eliminating the core processes in each of the three comparative groups, significant defects were observed in the product performance: the lack of corona treatment resulted in low surface energy, poor adhesion, and significant adhesive residue; the lack of an embossed dotted adhesive layer led to poor air removal, fewer re-lamination cycles, and numerous air bubbles; and the lack of post-curing resulted in unstable interfacial bonding, poor high-temperature resistance, and low strength. This fully demonstrates that the various process steps in the preparation method of this invention work synergistically to achieve the core performance advantages of the product. Compared to existing technologies, it solves the technical problems of insufficient adhesion, easy adhesive residue after re-lamination, difficulty in air bubble removal, and poor stability of traditional glass films, possessing extremely high practical value and market application prospects.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a multi-purpose, high-adhesion, re-adhesive glass film, characterized in that, Includes the following steps: Step a: Select a flexible polymer film with a thickness of 25μm to 100μm as the substrate layer, place it in a clean room, and treat one surface of the film with an online corona treatment machine at a power of 1.5kW to 2.5kW and a speed of 10m / min to 20m / min to increase its surface tension to more than 50dyn / cm, forming an activated surface for coating the inkjet printing layer; Step b: Prepare the inkjet printing layer coating solution, which contains 5% to 8% inorganic nano-silica, 2% to 4% polyvinylpyrrolidone, 0.1% to 0.3% leveling agent, and deionized water by mass fraction; place the substrate layer obtained in step a on the unwinding end of a precision coating machine with the activated surface facing upwards, and apply the coating solution evenly to the activated surface using a microgravure coating method under the conditions of temperature 20°C to 25°C and humidity 45% to 55%, with a wet film coating thickness of 10μm to 15μm; immediately after coating, introduce the substrate layer into an oven at a temperature of 80°C to 100°C for drying for 1 to 2 minutes, finally forming an inkjet printing layer with a dry film thickness of 5μm to 8μm; Step c: The substrate layer with inkjet printing layer after step b is introduced into the preheating area. The preheating temperature is set to 50°C to 60°C. The winding and unwinding tension is adjusted to keep the substrate layer flat and wrinkle-free before entering the lamination process. The winding tension is controlled between 1.5 kgf and 2.5 kgf. Step d: Select low-density polyethylene masterbatch with a thickness of 30μm to 80μm, and prepare a release film substrate through a casting process. While the casting temperature is between 150℃ and 180℃, immediately press the film surface with an embossing roller bearing a small dot pattern to form embossed units with a diameter of 0.5mm, thus obtaining a polyethylene embossed release film. On the embossed surface of the polyethylene embossed release film, apply water-based hot melt adhesive using an anilox roller coating device at a coating temperature of 2... The viscosity of the water-based hot melt adhesive is 1500 cps to 2500 cps at a temperature of 5°C to 30°C. The line count of the anilox roller is set to 150 lines per inch, and the coating speed is controlled at 15 m / min to 25 m / min. This allows the adhesive to form a matrix dotted structure on the release film surface that matches the embossing. The film is then cured in an oven at a temperature of 90°C to 110°C for 1.5 minutes to 3 minutes, forming a bonding layer with a dry adhesive thickness of 5 μm to 20 μm. Step e: With the side with the inkjet printing layer facing outwards, place the preheated substrate layer obtained in step c into a roller laminating machine with the other side facing the cured adhesive layer on the polyethylene embossed release film obtained in step d. The roller laminating machine is then used for hot pressing. The temperature of the hot pressing roller is set to 70°C to 80°C, the linear pressure is set to 3 kgf / cm to 5 kgf / cm, and the laminating linear speed is consistent with the coating speed in step d. Step f: The semi-finished product after step e is placed in a post-curing zone at a temperature of 45℃ to 55℃ and cured for 24 to 48 hours to form a stable interface bond between the bonding layer and the inner surface of the substrate layer. After curing, the wide roll material is cut into the width specifications required by the customer by a slitting machine and wound up in a constant temperature and humidity environment with the winding tension controlled at 1.0 kgf to 1.5 kgf to obtain the finished roll material.

2. The method for preparing a multi-purpose, high-adhesion, re-adhesive glass film according to claim 1, characterized in that, The online corona treatment machine described in step a adopts a dual-electrode structure with an electrode spacing of 1.2 mm and a processing frequency of 20 kHz, ensuring that a uniform micro-roughening structure can be formed on the surface of the substrate film during the treatment process.

3. The method for preparing a multi-purpose, high-adhesion, re-adhesive glass film according to claim 1, characterized in that, The inorganic nano-silica in step b has a particle size range of 20nm to 50nm. When preparing the coating solution, the inorganic nano-silica is first uniformly dispersed in deionized water under ultrasonic action for 30 minutes at a power of 500W. Then, polyvinylpyrrolidone and leveling agent are added, and the mixture is stirred at 300rpm for 2 hours at room temperature to form a uniform and stable coating solution suspension system.

4. The method for preparing a multi-purpose, high-adhesion, re-adhesive glass film according to claim 1, characterized in that, The specific process parameters for the microgravure coating method described in step b are as follows: a gravure roller with a screen count of 200 lines per inch is used, the doctor blade pressure is 0.2 MPa, the coating angle is 30 degrees, the coating gap is set to 0.1 mm, ensuring that the wet film thickness is uniform and the coating CV value is controlled within 3%.

5. The method for preparing a multi-purpose, high-adhesion, re-adhesive glass film according to claim 1, characterized in that, The specific operation of the anilox roller coating equipment in step d includes: immersing the anilox roller coated with adhesive into the adhesive storage tank, controlling the amount of adhesive transferred to the roller surface by a metering scraper, and then transferring the adhesive to the embossed surface of the polyethylene embossed release film running at a constant speed by roller-to-roll. During the transfer process, the running tension of the release film is controlled to be 1.0 kgf to 1.2 kgf.

6. The method for preparing a multi-purpose, high-adhesion, re-adhesive glass film according to claim 1, characterized in that, The composition of the water-based hot melt adhesive in step d is as follows: by mass, it comprises 35 to 45 parts of ethylene-vinyl acetate copolymer emulsion, 20 to 30 parts of acrylic pressure-sensitive adhesive emulsion, 5 to 10 parts of hydrogenated rosin glycerol ester, 1 to 3 parts of polyethylene glycol, and 0.5 to 1 part of polyether-modified polysiloxane defoamer.

7. The method for preparing a multi-purpose, high-adhesion, re-adhesive glass film according to claim 1, characterized in that, The composite rollers of the roller laminating machine mentioned in step e are silicone-coated rollers with a Shore A hardness of 60 to 70 degrees. During lamination, the gap between the two rollers is controlled to be 1.1 to 1.2 times the total thickness of the substrate layer, the bonding layer and the release film layer.

8. The method for preparing a multi-purpose, high-adhesion, re-adhesive glass film according to claim 1, characterized in that, Between step e and step f, there is also step e1: preliminary cooling and shaping, in which the composite semi-finished product is immediately introduced into a cooling roller group with a temperature of 15°C to 20°C, the surface temperature of the cooling roller is 10°C to 15°C, and the cooling time is 5 seconds to 10 seconds, so that the composite structure is initially shaped and interlayer displacement is prevented due to thermal stress.

9. The method for preparing a multi-purpose, high-adhesion, re-adhesive glass film according to claim 1, characterized in that, The control conditions for the constant temperature and humidity environment mentioned in step f are: temperature 23℃±2℃, relative humidity 50%±5%, the rotation speed of the circular blade of the slitting machine is 500rpm to 800rpm, and the width of the burrs produced during slitting is less than 0.2mm.

10. A multi-purpose, high-adhesion, re-adhesive glass film prepared by the method according to any one of claims 1 to 9, characterized in that, The device comprises, from the outside in, an inkjet printing layer, a substrate layer, an adhesive layer, and a release film layer, arranged sequentially. The inkjet printing layer is a surface that has undergone corona treatment and is coated with a mixed coating of inorganic nano-silica and polyvinylpyrrolidone. The substrate layer is a nylon film or polyethylene terephthalate film that has been preheated and tension-controlled. The adhesive layer is a water-based hot melt adhesive layer coated on the embossed surface of the polyethylene embossed release film by an anilox roller, and its shape is a matrix dot structure. The release film layer is a polyethylene embossed release film with tiny dot embossed units with a diameter of 0.5 mm on its surface.

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