Foldable glass with integral film and foldable glass
By designing an integrated membrane structure, the problems of cumbersome process flow and high equipment cost in UTG production were solved, achieving the effects of simplifying the production process, reducing costs and improving product yield.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- LENS TECH CHANGSHA
- Filing Date
- 2025-07-30
- Publication Date
- 2026-07-03
AI Technical Summary
The existing UTG production process is cumbersome, with high equipment and personnel costs. The bending performance of UTG monomers is easily damaged, and there are risks of scratches and particulate matter introduction during the film tearing and replacement process, which affects the production yield.
The integrated membrane structure includes a release film, an adhesive layer, and a substrate. The initial tack of the adhesive layers increases sequentially, and the elongation at break of the second adhesive layer is greater than that of the first and third adhesive layers. The substrate has excellent temperature resistance and can be directly shipped to subsequent processes after the flexural bending test, simplifying the production process, reducing costs, and improving product yield.
It simplifies the UTG production process, reduces production costs, improves the production yield of UTG products, avoids the risk of damage and scratches to UTG monomers during the film tearing and film replacement process, and ensures the stability and efficiency of production.
Smart Images
Figure CN224447123U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of foldable screen technology, specifically to an integrated film for foldable glass and foldable glass. Background Technology
[0002] With the continuous development of technology, foldable screen electronic products have gradually gained popularity among consumers due to their unique appearance and user experience. As the display cover for foldable screen electronic products, ultra-thin flexible foldable glass (UTG) has also experienced rapid development. Foldability is one of the most important performance characteristics of UTG, and folding resistance testing, as a crucial method for evaluating the bending performance of individual UTG units, is now a mandatory inspection item before each UTG unit leaves the factory. Before conducting folding resistance testing, given the good tensile and deformation resistance of polyethylene film (PE film), a PE film laminating machine is used to coat both sides of the UTG unit with PE film for protection. After testing, due to the poor temperature resistance of PE film, shrinkage and deformation will occur during the subsequent lamination process, after plasma cleaning and high-temperature degassing. Therefore, a film peeling machine must be used to remove the PE film, and a polyurethane film laminating machine must be used to replace it with a PU film with better temperature resistance. The UTG with the PU film is then shipped to the downstream lamination process. PU film serves as a protective film during shipment, used in subsequent lamination processes. The entire process involves four types of equipment: a PE film laminating machine, a bending machine, a PE film peeling machine, and a PU film laminating machine. This not only lengthens the production line and significantly increases equipment and labor costs, but also poses a risk of damage to the bending performance of UTG monomers during the process of removing the PE film and replacing it with the PU film after the staggered bending test. Furthermore, the film peeling and replacement process may also result in scratches on the UTG or the introduction of particulate matter, all of which can lead to a decrease in UTG bending performance and consequently negatively impact production yield. Utility Model Content
[0003] The purpose of this invention is to provide an integrated protective film for foldable glass that can simplify the UTG production process, reduce production costs, and improve the yield of UTG products.
[0004] To achieve the above objectives, a first aspect of this utility model provides an integrated film for foldable glass, which sequentially comprises: a release film, an adhesive layer, and a substrate; the adhesive layer sequentially comprises a first adhesive layer, a second adhesive layer, and a third adhesive layer; wherein the initial adhesive strength of the first adhesive layer, the second adhesive layer, and the third adhesive layer increases sequentially; and the elongation at break of the second adhesive layer is greater than the elongation at break of the first adhesive layer and the third adhesive layer.
[0005] In the embodiments of this application, the thickness of the first adhesive layer is 5-10 μm; and / or, the elongation at break of the first adhesive layer is >300%; and / or, the softening temperature of the first adhesive layer is >150°C; and / or, the water contact angle of the first adhesive layer is 20-35°; and / or, the first adhesive layer is selected from adhesive layers containing urethane groups.
[0006] In the embodiments of this application, the thickness of the second adhesive layer is 5-10 μm; and / or, the viscosity of the second adhesive layer before curing at 25°C is less than 26000 cps; and / or, the second adhesive layer is selected from adhesive layers with acrylate resin as the main component.
[0007] In the embodiments of this application, the thickness of the third adhesive layer is 16-20 μm; and / or, the third adhesive layer is selected from adhesive layers with acrylic resin as the main component.
[0008] In the embodiments of this application, the thickness of the substrate is 21-36 μm; and / or, the temperature resistance of the substrate is ≥120℃; and / or, the flexural strength of the substrate is 140-310 MPa, and the elastic modulus is 3500-4500 MPa; and / or, the substrate is selected from PET substrate or fluorinated PI substrate.
[0009] The second aspect of this utility model provides a foldable glass, which includes a UTG layer and an integral film adhered to one side of the UTG layer; the first adhesive layer of the integral film is in direct contact with the UTG layer; the integral film is the release film layer of the integral film for foldable glass described in the first aspect above.
[0010] In embodiments of this application, a protective film layer is attached to the other side of the UTG layer; and / or, the protective film layer is a PE film.
[0011] In the embodiments of this application, the thickness of the PE film layer is 25-35 μm; and / or, the elongation at break of the PE film is ≥500%.
[0012] In the embodiments of this application, the peel force of the first adhesive layer of the integrated film is 5-10 g / f.
[0013] In embodiments of this application, the first adhesive layer contains a curing agent.
[0014] The technical solution of this utility model has at least the following advantages:
[0015] (1) The integrated membrane provided by this utility model uses a substrate with good elasticity and excellent temperature resistance as a carrier, a third adhesive layer with good softness and tensile deformation as a bending buffer layer, a first adhesive layer with strong fatigue resistance as a bonding layer for UTG monomers, and a second adhesive layer with low viscosity as a bonding layer for the third adhesive layer and the first adhesive layer. Such an integrated membrane structure has excellent bendability. During the kinetic bending test, the integrated membrane will not separate from the UTG product and will not generate bubbles. At the same time, the first adhesive layer can ensure that no dust is generated during subsequent laser cutting, ensuring cleanliness, and it is easy to bond with UTG. During the bonding process of the integrated membrane, the contamination of UTG monomers can be minimized.
[0016] (2) The integrated film provided by this utility model can replace the PE test film on one side for the misalignment bending test. After the misalignment bending test, it can be directly shipped to the later stage (lamination stage) without replacing the PU film, which simplifies the production process.
[0017] (3) The technical solution provided by this utility model can improve the production yield of UTG products and save production materials, manpower and time costs. Attached Figure Description
[0018] Figure 1 This is a structural schematic diagram of an integrated film for foldable glass according to this utility model;
[0019] Figure 2 This is a schematic diagram of a foldable glass structure according to the present invention;
[0020] Figure 3 This is a schematic diagram of another foldable glass structure of this utility model;
[0021] Figure 4 This is a schematic diagram of the force direction during the folding test of the foldable glass of this utility model.
[0022] Figure 5 These are comparison charts showing the extreme bending tests of UTG products from different production lines using PE test membranes and integrated membranes.
[0023] Explanation of reference numerals in the attached figures
[0024] 1-Substrate; 2-Third adhesive layer; 3-Second adhesive layer; 4-First adhesive layer; 5-UTG layer; 6-Protective film layer; 7-Release film. Detailed Implementation
[0025] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0026] In this invention, unless otherwise stated, the "inner" and "outer" of the integrated membrane refer to the side closer to the UTG as the inner side and the side farther from the UTG as the outer side.
[0027] Terminology Explanation: UTG refers to ultra-thin flexible foldable glass; PE film refers to polyethylene film; PU film refers to film material with PET as the base material and PU adhesive (polyurethane adhesive) as the adhesive; PET film refers to polyester film; acrylic adhesive refers to polymethyl methacrylate; PLASMA refers to plasma cleaning; LOCA adhesive refers to acrylic liquid optical adhesive.
[0028] To achieve the above objectives, such as Figure 1 As shown, the first aspect of this utility model provides an integrated film for foldable glass, which sequentially comprises: a release film, an adhesive layer, and a substrate; the adhesive layer sequentially comprises a first adhesive layer, a second adhesive layer, and a third adhesive layer; wherein the initial tack of the first adhesive layer, the second adhesive layer, and the third adhesive layer increases sequentially; the elongation at break of the second adhesive layer is greater than the elongation at break of the first adhesive layer and the third adhesive layer. Those skilled in the art will understand that, due to the sequential increase in the initial tack of the first adhesive layer, the second adhesive layer, and the third adhesive layer, the third adhesive layer, compared to the first and second adhesive layers, can adhere to the substrate more quickly and firmly in a short time after contact with the substrate at room temperature, without generating bubbles, thereby achieving a rapid positioning effect. Simultaneously, through this gradient change in "initial tack," a more stable initial bonding effect can be achieved. This characteristic can effectively prevent slippage or interlayer misalignment during subsequent coating and lamination processes, thereby preventing adverse effects on product consistency. Meanwhile, because the elongation at break of the second adhesive layer is greater than that of the first and third adhesive layers, it has stronger deformation capability. Using it as a transition layer between the third and first adhesive layers effectively disperses lateral shear stress during bending and prevents delamination. This integrated membrane structure exhibits excellent bendability; during staggered bending tests, the integrated membrane will not separate from the UTG product, nor will it generate bubbles. Furthermore, because the integrated membrane is heat-resistant after the release film is removed, it overcomes the drawbacks of traditional solutions, such as cumbersome processes and poor compatibility with high-temperature operations.
[0029] In some embodiments, the thickness of the first adhesive layer is 5-10 μm. With this thickness, the first adhesive layer, in conjunction with the second adhesive layer, further enhances the tensile strength of the integral film.
[0030] In some preferred embodiments, the elongation at break of the first adhesive layer is >300%. Under this condition, the first adhesive layer exhibits excellent fatigue resistance. The elongation at break of the first adhesive layer exceeding 300% causes it to adhere closer to the UTG side during flexural bending, making it less prone to cracking even with repeated bending, whereas traditional acrylic adhesive (polymethyl methacrylate adhesive) may develop microcracks after 1000 bends.
[0031] In some preferred embodiments, the softening temperature of the first adhesive layer is >150°C. Under this condition, the first adhesive layer exhibits excellent high-temperature stability and can directly withstand high-temperature PLASMA cleaning and high-temperature defoaming processes.
[0032] In some preferred embodiments, the water contact angle of the first adhesive layer is 20-35°. Under this condition, the first adhesive layer will not generate dust during subsequent laser cutting into smaller pieces, thus maintaining good cleanliness.
[0033] In some preferred embodiments, the first adhesive layer is selected from adhesive layers containing urethane groups. Because urethane groups contain a large number of flexible groups (such as urethane bonds and ether bonds), they impart high elasticity and deformation recovery ability. Even with repeated bending, the molecular chains can disperse stress through stretching and contraction, making them less prone to breakage or cracking. Optionally, the first adhesive layer is a PU adhesive layer.
[0034] The first adhesive layer used in this invention can withstand the principal bending stress, meet the cleanliness requirements of laser cutting, and control the peeling force. As an integral film in the UTG production process, it is directly bonded to UTG, which can simplify the production process, improve product yield, and reduce production material, labor and time costs.
[0035] According to one specific embodiment, the thickness of the second adhesive layer is 5-10 μm. This invention uses the second adhesive layer as an adhesive layer between the third adhesive layer and the first adhesive layer. Under this thickness condition, the second adhesive layer, combined with both the third and first adhesive layers, can further improve the tensile strength of the integrated film.
[0036] In some preferred embodiments, the viscosity of the second adhesive layer at 25°C before curing is less than 26,000 cps. Because the second adhesive layer has low viscosity and high fluidity, it can spread more evenly on the first adhesive layer, more efficiently expel air bubbles before curing, and after curing, it exhibits a flexible gel state with superior deformation capacity compared to the first and third adhesive layers, effectively dispersing lateral shear stress during bending.
[0037] In some preferred embodiments, the second adhesive layer is selected from adhesive layers with acrylate resins as the main component. Since acrylate resins have a polar molecular structure, they can form hydrogen bonds with acrylic acid and polyurethane, which can improve interfacial bonding strength and prevent interfacial slippage. Furthermore, the second adhesive layer is bonded to both the third and first adhesive layers, thereby improving the deformation resistance of both the third and first adhesive layers. Optionally, the second adhesive layer is a LOCA adhesive layer.
[0038] According to one specific embodiment, the thickness of the third adhesive layer is 16-20 μm. This invention involves coating a third adhesive layer onto a substrate. Under this thickness condition, the third adhesive layer, combined with both the second adhesive layer and the substrate, can further improve the tensile strength of the integrated film.
[0039] In some preferred embodiments, the third adhesive layer is selected from adhesive layers with acrylic resin as the main component. During the staggered bending test, the bending of the substrate will compress the third adhesive layer, and the third adhesive layer (acrylic) has a certain tensile deformation resistance effect, which can protect the substrate; the third adhesive layer has strong resilience after bending, and the adhesive layer can recover quickly, with slight creases; in addition, the third adhesive layer (acrylic) has strong initial tack, and it can firmly adhere in a short time after contact, so no air bubbles are generated during the bending test, while the first adhesive has relatively low initial tack and requires a longer time or heating to achieve stable bonding. In the integrated film preparation stage, it is necessary to quickly fix the positions of the second adhesive layer and the first adhesive layer to prevent slippage during subsequent coating or lamination. The high initial tack of the third adhesive layer can ensure rapid positioning at room temperature. If the first adhesive layer or the second adhesive layer is used to bond with the substrate, the insufficient initial adhesion may lead to interlayer misalignment, affecting product consistency.
[0040] According to one specific embodiment, the thickness of the substrate is 21-36 μm.
[0041] In some preferred embodiments, the temperature resistance of the substrate is ≥120°C.
[0042] In some preferred embodiments, the flexural strength of the substrate is 140-310 MPa and the elastic modulus is 3500-4500 MPa.
[0043] In some preferred embodiments, the substrate is selected from PET substrate or fluorinated PI substrate.
[0044] This invention uses a substrate of appropriate thickness and excellent temperature resistance as a carrier, suitable for PLASM cleaning and high-temperature degassing processes; it also possesses excellent mechanical properties, capable of resisting mechanical deformation during coating and bonding processes. Optionally, the substrate is a PET substrate or a fluorinated PI substrate, which have excellent heat resistance and thermal stability, and moderate flexibility, meeting the requirements of bending tests.
[0045] The second aspect of this utility model provides a foldable glass, which includes a UTG layer and an integral film adhered to one side of the UTG layer; the first adhesive layer of the integral film is in direct contact with the UTG layer; the integral film is the film layer of the foldable glass integral film described in the first aspect after the release film has been removed.
[0046] The integrated film provided by this utility model has a temperature resistance of over 80℃. When it undergoes high-temperature cleaning and high-temperature degassing in the PLASMA laminating machine, the material will not shrink or deform. It can be fully automatically laminated on a fully automatic laminating machine without the need to replace it with another protective film, thus simplifying the production process.
[0047] The aforementioned foldable glass provided by this utility model can serve as an intermediate product in the UTG product manufacturing process. The integrated film, as a protective film in the UTG product manufacturing process, can be peeled off and replaced with a shipping film before the UTG product is shipped. After the foldable glass formed by the UTG layer and the integrated film provided by this utility model is laminated as described above, it can be laser-cut to the desired size without generating dust on the surface, and without affecting the subsequent application of the shipping film. The first adhesive layer plays the role of an adhesive trapping net and a physical isolation shield during laser cutting. Its core functions are: A. Melting to form an adhesive layer: The laser melts it, generating a highly viscous liquid layer; B. Effectively capturing particles: This adhesive layer adheres to and encapsulates all the tiny solid particles generated during the cutting of the underlying substrate; C. Blocking escape channels: Forming a barrier to prevent particles from scattering into the air. Therefore, when laser-cutting materials with a first adhesive layer, the first adhesive layer acts as a protective layer, greatly reducing the amount of dust generated and significantly improving the working environment.
[0048] According to a preferred embodiment, a protective film layer is adhered to the other side of the UTG layer. Optionally, the protective film layer is a PE film. Under this preferred condition, the foldable glass can be used to perform a kink bending test on the UTG product. After the kink bending test, the product can be directly shipped to the downstream lamination stage; only the PE film layer needs to be peeled off for lamination. Furthermore, the integrated underfilm adopts a composite structure of substrate + third adhesive layer + second adhesive layer + first adhesive layer, resulting in high stress and greater suction force with the vacuum plate than the adhesion force between the upper protective film layer and the product, making the protective film easy to remove.
[0049] Figure 4An exemplary schematic diagram of the force direction during the foldable glass slippage and bending test of this utility model is provided, wherein the innermost layer is a PE film layer and the outermost layer is a substrate; wherein, the letter N represents the downward pressure and S represents ±20mm slippage.
[0050] In some embodiments, the thickness of the PE film layer is 25-35 μm.
[0051] In some embodiments, the elongation at break of the PE film is ≥500%. The PE film has good tensile and deformation resistance. During the bending test, the PE film is in the middle and experiences the greatest stress. During staggered bending, the PE film in the bending area can stretch and deform with the product. The film material in the bending area will not separate from the product, will not generate bubbles, and will have slight creases after recovery.
[0052] According to a preferred embodiment, the peel force of the first adhesive layer of the integrated film is 5-10 g / f. If the peel force of the first adhesive layer is too low, it will easily detach from the UTG surface during bending tests; if it is too high, it will be difficult to peel off, affecting the subsequent replacement of the film. Under this preferred condition, the expected effect of this invention can be achieved.
[0053] According to a preferred embodiment, the first adhesive layer contains a curing agent. Preferably, the curing agent content in the first adhesive layer is 3.5-4.5 wt%, more preferably 4 wt%. Under this condition, the peel force of the first adhesive layer can be precisely controlled within the expected range.
[0054] Traditional UTG production processes require four types of equipment: PE film laminating machine, bending machine, PE film tearing machine, and PU film laminating machine. This lengthens the production line and significantly increases equipment and personnel costs. Furthermore, there is a risk that the bending performance of the UTG monomers may be affected during the process of tearing off the PE film and replacing it with the PU film after the staggered bending test. There is also a risk that the UTG may be scratched during the film tearing and replacement process, leading to a decrease in the bending performance of the UTG, as well as the risk of particulate matter being introduced, thus affecting the production yield.
[0055] The integrated foldable glass film provided by this invention features complementary functions in each layer, exhibiting excellent bendability. During staggered bending tests, the film material does not separate from the product, and no air bubbles are generated. After the staggered bending test, it can be directly sent to the subsequent lamination process, meeting the automatic film-tearing operation of fully automated laminating machines. High-temperature cleaning and debubbling of PLASMA do not cause shrinkage or deformation. This achieves a high degree of integration between the bending resistance test and the hot-press lamination process.
[0056] In some embodiments, the post-lamination process of this utility model includes: first removing the protective film, cleaning with PLASMA, laminating OCA (optically transparent special adhesive film), then laminating HC-PET (hardened PET protective film), and finally performing high-temperature degassing.
[0057] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials used are common commercial products.
[0058] Example 1
[0059] like Figure 3 The foldable glass shown here has the following specific structural parameters, as shown in Table 1:
[0060] Table 1
[0061]
[0062] Example 2
[0063] like Figure 3 The foldable glass shown here has the following specific structural parameters, as shown in Table 2:
[0064] Table 2
[0065]
[0066] Comparative Example 1
[0067] A PE film layer with a thickness of 30 μm is bonded to both sides of the UTG layer. The UTG layer is the same as in Example 1.
[0068] Test Example 1
[0069] Offset bending test: The test was conducted using a PE laminating machine and a bending machine (fully automatic bending machine, manufactured by Amphenol), with the innermost layer being a PE film layer.
[0070] The test parameters and test results are shown in Table 3.
[0071] Table 3
[0072]
[0073] In Table 3, CO1 and DO1 both refer to UTG product models; 50μmC product refers to UTG products with apparent defects and a thickness of 50μm.
[0074] As shown in Table 3, the foldable integrated glass film provided by this invention is more suitable for UTG slip bending tests. Compared with the traditional double-sided 30μm thick PE film slip bending test, the technical solution of this invention can achieve comparable or even better product yield. Furthermore, it can be directly shipped to the lamination process without replacing the PE film with a PU film, simplifying the production process and saving on production materials, labor, and time costs.
[0075] Test Example 2
[0076] Limit bending test method: Bending test, press down until the product breaks at the limit plate spacing.
[0077] Test results are as follows Figure 5 As shown, Figure 5 Comparison of extreme bending tests for UTG products from different production lines using PE film on both sides versus using an integrated film on one side and PE film on the other. The vertical axis L represents the extreme plate spacing. The thickness of the UTG layer is 50μm in both cases, and the integrated film structure is the same as in Example 1.
[0078] exist Figure 5 In the text, UTG-1 refers to the UTG products on production line 1 undergoing extreme bending tests using double-layer PE film; UTG-2 refers to the UTG products on production line 2 undergoing extreme bending tests using double-layer PE film; UTG-3 refers to the UTG products on production line 3 undergoing extreme bending tests using double-layer PE film; and UTG-4 refers to the UTG products on production line 4 undergoing extreme bending tests using an integrated film on one side and a PE film on the other side.
[0079] from Figure 5 The results show that, compared to the UTG products tested with an integrated film during extreme bending tests on different production lines, the data from the integrated film test for UTG products is roughly the same as, and even slightly better than, the data from the PE test film test for UTG products. Therefore, in the kinetic bending test, the integrated film can replace one side of the PE test film.
[0080] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A foldable glass with integral film, characterized by, The integrated film for foldable glass comprises, in sequence: a release film, an adhesive layer, and a substrate; The adhesive layer comprises, in sequence, a first adhesive layer, a second adhesive layer, and a third adhesive layer; The initial adhesive strength of the first adhesive layer, the second adhesive layer, and the third adhesive layer increases sequentially. The elongation at break of the second adhesive layer is greater than that of the first adhesive layer and the third adhesive layer.
2. The foldable glass unitary film of claim 1, wherein, The thickness of the first adhesive layer is 5-10 μm; And / or, the elongation at break of the first adhesive layer is >300%; And / or, the softening temperature of the first adhesive layer is >150°C; And / or, the water contact angle of the first adhesive layer is 20-35°; And / or, the first adhesive layer is selected from adhesive layers containing urethane groups.
3. The integrated film for foldable glass according to claim 1, characterized in that, The thickness of the second adhesive layer is 5-10 μm; And / or, the viscosity of the second adhesive layer before curing at 25°C is less than 26000 cps; And / or, the second adhesive layer is selected from adhesive layers whose main component is an acrylic resin.
4. The foldable glass unitary film of claim 1, wherein, The thickness of the third adhesive layer is 16-20 μm; And / or, the third adhesive layer is selected from adhesive layers with acrylic resin as the main component.
5. The foldable glass unitary film of claim 1, wherein, The thickness of the substrate is 21-36 μm; And / or, the temperature resistance of the substrate is ≥120℃; And / or, the flexural strength of the substrate is 140-310 MPa, and the elastic modulus is 3500-4500 MPa; And / or, the substrate is selected from PET substrate or fluorinated PI substrate.
6. A foldable glass, characterized by, The foldable glass includes a UTG layer and an integral film adhered to one side of the UTG layer; the first adhesive layer of the integral film is in direct contact with the UTG layer; the integral film is the release film layer of the integral film for foldable glass as described in any one of claims 1-5.
7. The foldable glass of claim 6, wherein, A protective film layer is attached to the other side of the UTG layer; And / or, the protective film layer is a PE film.
8. The foldable glass of claim 7, wherein, The thickness of the PE film layer is 25-35 μm; And / or, the elongation at break of the PE film is ≥500%.
9. The foldable glass according to claim 6, characterized in that, The peel force of the first adhesive layer of the integrated film is 5-10 g / f.
10. The foldable glass of claim 9, wherein, The first adhesive layer contains a curing agent.