Liquid crystal dimming glass having asymmetric structure

Abstract

The present application discloses liquid crystal dimming glass having an asymmetric structure, comprising a first transparent substrate, a first film layer, a dimming film layer, a second film layer and a second transparent substrate which are laminated, pasted and fixed. The thickness of the first transparent substrate and the first film layer is necessarily smaller than that of the second transparent substrate and the second film layer, guaranteeing that the film layers and the substrates on two sides of the dimming film layer are of an asymmetric structure, so that the stress field of the dimming film layer after the high-temperature and high-pressure lamination process is asymmetrically distributed, which facilitates releasing the stress when the dimming film layer returns to the room temperature, thereby reducing the residual stress. The residual stress of the dimming film layer is significantly lower than that of the traditional liquid crystal dimming glass, avoiding liquid crystal aggregation in the dimming film layer, effectively solving the problem of uneven color after lamination.

Description

Asymmetric structure liquid crystal dimming glass Technical Field

[0001] The present application relates to the technical field of dimming glass, and in particular to a liquid crystal dimming glass with an asymmetric structure. Background Art

[0002] Currently, switchable glass is used in architecture, transportation, and other fields. It can change light transmittance, thereby switching between dark and bright states. The traditional production method for switchable glass involves sandwiching a liquid crystal switchable film between two sheets of glass via a film layer. As shown in Figure 1, the two sheets of glass are generally of equal thickness, and the film layer between the two sheets of glass and the liquid crystal switchable film is also generally of equal thickness, resulting in a symmetrical structural design. In this symmetrical design, the liquid crystal switchable film serves as the plane of symmetry, and the film layers on both sides, as well as the glass layers, maintain consistent or similar thicknesses. The traditional switchable glass assembly process requires a necessary step in the high-pressure, high-temperature environment in which the film layer melts and flows, causing the liquid crystals in the liquid crystal switchable film to move. As the film layer cools and solidifies, significant residual stress forms due to the significant differences in thermal expansion coefficients between the liquid crystal switchable film, the film layer, and the glass. This stress prevents the liquid crystals from returning to their original positions after movement, causing them to aggregate in areas of high stress inhomogeneity, resulting in color unevenness across the switchable glass. As shown in Figure 2, this symmetrically designed switchable glass exhibits color clustering or uneven color. This creates a relatively symmetrical stress field when the glass is laminated, making it difficult to effectively release residual stress. Furthermore, most existing switchable glass laminates use relatively thick glass, such as 1.85mm or 2.1mm. This high rigidity hinders the release of residual stress and can easily lead to the aforementioned uneven color.

[0003] Application Contents

[0004] The main purpose of this application is to propose an asymmetric structure liquid crystal dimming glass, which aims to solve the technical problem of color unevenness of the current dimming glass in the lamination process.

[0005] To achieve the above objectives, the present application proposes an asymmetric liquid crystal dimming glass. The asymmetric liquid crystal dimming glass comprises a first transparent substrate, a first film layer, a dimming film layer, a second film layer, and a second transparent substrate that are laminated and bonded together. The thickness of the first transparent substrate is less than or equal to 60% of the thickness of the second transparent substrate, and the thickness of the first transparent substrate ranges from greater than or equal to 0.15 mm to less than or equal to 1.3 mm. Preferably, the thickness of the first transparent substrate plus the first film layer is less than the thickness of the second transparent substrate plus the second film layer. The first and second transparent substrates can be made of glass or flexible transparent optical materials, such as polycarbonate, polyethylene terephthalate, etc.

[0006] Furthermore, the thickness of the second film layer is greater than or equal to the thickness of the first film layer.

[0007] Furthermore, the thickness range of the first film layer is greater than or equal to 0.15 mm and less than or equal to 1.6 mm, and the thickness range of the second film layer is greater than or equal to 0.3 mm and less than or equal to 2.5 mm.

[0008] Furthermore, the thickness of the second transparent substrate is greater than or equal to 1.5 mm and less than or equal to 3 mm.

[0009] Furthermore, the second film layer is formed by stacking several third film layers of the same thickness. The first film layer can also be formed by stacking several third film layers of the same thickness, but the number of stacked second film layers will be greater than the number of stacked first film layers. The thickness of the first and second film layers can be adjusted by controlling the number of third film layers.

[0010] Furthermore, the first film layer and the second film layer can be interchanged.

[0011] Furthermore, the first transparent substrate and the second transparent substrate are glass layers or transparent layers of flexible transparent optical materials.

[0012] Furthermore, the first film layer and the second film layer are one or more of ethylene-vinyl acetate copolymer, polyvinyl butyral, thermoplastic polyurethane elastomer, ionomer, and optically transparent adhesive material layer.

[0013] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0014] The present application proposes an asymmetric structure liquid crystal dimming glass, in which the film layer and the substrate on both sides of the dimming film layer in the dimming glass have a significant difference in thickness. The stress field of the dimming film layer in this asymmetric structure liquid crystal dimming glass after the high-temperature and high-pressure lamination process will show an asymmetric distribution, which helps to release the stress after returning to room temperature, thereby reducing residual stress. The residual stress in the dimming film layer is significantly lower than that of the symmetrical structure of traditional liquid crystal dimming glass, avoiding liquid crystal aggregation in the dimming film layer and effectively solving the problem of color unevenness after lamination. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG1 is a schematic diagram of the structure of a conventional switchable glass;

[0016] FIG2 is a schematic diagram showing the color unevenness of conventional switchable glass in a dark state;

[0017] FIG3 is a schematic structural diagram of the asymmetric liquid crystal dimming glass of Example 1;

[0018] FIG4 is a schematic diagram of the asymmetric structure liquid crystal dimming glass of Example 1 with uniform color in a dark state;

[0019] FIG5 is a schematic structural diagram of the asymmetric liquid crystal dimming glass according to Example 2;

[0020] FIG6 is a schematic structural diagram of the asymmetric liquid crystal dimming glass according to Example 3;

[0021] FIG7 is a schematic structural diagram of the asymmetric liquid crystal dimming glass according to Example 4.

[0022] Description of Figure Numbers:

[0023] 10: First transparent substrate; 11: First film layer; 12: Smart film layer; 13: Second film layer; 14: Second transparent substrate; 15: Third film layer; 1001: Glass substrate of traditional smart glass; 1000: Smart film of traditional smart glass; 1002: Adhesive layer of traditional smart glass. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the schemes in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments in this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0025] Example 1

[0026] Please refer to Figures 1 and 2. Figure 1 is a schematic diagram of the structure of a conventional switchable glass. In conventional switchable glass, the adhesive layer 1002 on either side of the switchable film 1000 and the glass substrate 1001 are made of the same thickness and are laminated together, resulting in a symmetrical structure with the switchable film as the symmetry plane. Figure 2 illustrates the color unevenness that occurs when the conventional switchable glass is laminated. This conventional switchable glass is subjected to the high-pressure, high-temperature lamination environment, where the adhesive layer melts and flows, causing the liquid crystals in the switchable film 1000 to shift. As the adhesive layer cools and solidifies, significant residual stress forms due to the significant difference in thermal expansion coefficients between the switchable film, adhesive layer, and glass substrate. This stress prevents the liquid crystals from fully returning to their original positions, causing them to aggregate in certain areas of uneven stress, resulting in color unevenness across the switchable film. As shown in Figure 2, switchable glass with this symmetrical structural design can experience color aggregation or unevenness. During lamination, a relatively symmetrical stress field forms, making it difficult to effectively release the residual stress. The dimming glass product shown in Figure 2 uses a 2.1mm thick glass substrate. Due to its high rigidity, this type of glass is not conducive to the release of residual stress and is also prone to the color unevenness phenomenon mentioned above.

[0027] Referring to Figure 3 , this embodiment provides an asymmetric liquid crystal dimming glass. The asymmetric liquid crystal dimming glass comprises a first transparent substrate 10, a first film layer 11, a dimming film layer 12, a second film layer 13, and a second transparent substrate 14, which are laminated and bonded together. The second film layer 13 is formed by stacking multiple third film layers 15 of equal thickness. The first film layer 11 can also be formed by stacking multiple third film layers 15 of equal thickness, but the number of stacked second film layers 13 will be greater than the number of stacked first film layers 11. The thickness of the first and second film layers 11, 13 can be adjusted by controlling the number of third film layers 15.

[0028] In this embodiment, the first transparent substrate 10 is made of 0.7mm tempered glass, the second transparent substrate 14 is made of 2.1mm tempered glass, and the third film is a 0.76mm thick ethylene-vinyl acetate copolymer film. The dimming film 12 is based on a flexible substrate and is manufactured using liquid crystal technology. The first film layer 11 comprises a single third film layer 15, while the second film layer 13 comprises three third film layers 15. The dimming glass constructed with these thicknesses ensures an asymmetric structure on both sides of the dimming film 12. In particular, the first transparent substrate 10 and the second transparent substrate 14 have different and significant thickness differences.

[0029] In this embodiment, the steps for manufacturing the asymmetric liquid crystal dimming glass are as follows:

[0030] Step 1: First, clean the surfaces of the first transparent substrate 10 and the second transparent substrate 14 to ensure that there is no dust, oil stains or any other impurities on the surfaces of the first transparent substrate 10 and the second transparent substrate 14.

[0031] Step 2: Cut the third film layer 15 , ie, the ethylene-vinyl acetate copolymer film with a thickness of 0.76 mm, according to the size requirements of the first transparent substrate 10 and the second transparent substrate 14 , and ensure that the EVA film is flat and has no defects.

[0032] Step 3: Following the specified machine configuration, place the first and second transparent substrates 10 and 14, the ethylene-vinyl acetate copolymer film, and the dimming film layer 12 in a vacuum bag designed for laminated glass. Evacuate the bag at a pressure of -0.1 MPa and maintain this pressure for 30 minutes to eliminate any bubbles in the film layer.

[0033] Step 4: After evacuating for 30 minutes, while maintaining the vacuum, transfer the sample from the vacuum bag to the oven. First, raise the temperature to 70°C and maintain it for 20 minutes; then, raise the temperature to 115°C and maintain it for another 30 minutes.

[0034] Step 5: When the heating process is finished, turn off the oven and let the sample cool naturally. When the temperature of the sample drops to 40°C, it can be taken out of the oven.

[0035] Step 6: Finally, the finished product undergoes a rigorous visual inspection to ensure it is completely free of bubbles, cracks, or other defects. The excess EVAC film and glass edges are then trimmed off.

[0036] After the above steps, a finished product is made. FIG4 shows the display condition of the finished dimming glass in a dark state. In the dark state, the color displayed by the dimming glass is uniform.

[0037] Example 2

[0038] Referring to Figure 5 , this embodiment provides an asymmetric liquid crystal dimming glass. The asymmetric liquid crystal dimming glass comprises a first transparent substrate 10, a first film layer 11, a dimming film layer 12, a second film layer 13, and a second transparent substrate 14, which are laminated and bonded together. The first film layer 11 and the second film layer 13 are formed by a third film layer 15. The first transparent substrate 10 is made of 1.1mm tempered glass, the second transparent substrate 14 is made of 1.85mm tempered glass, and the third film layer is a 0.76mm thick polyvinyl butyral film. The dimming film layer 12 is a dimming film made on a flexible substrate using liquid crystal technology. The first film layer 11 and the second film layer 13 both use two layers of the third film layer 15. In the dimming glass having the above-mentioned thickness, the first film layer 11 and the second film layer 13 are of equal thickness, while the second transparent substrate 14 is thicker than the first transparent substrate 10, ensuring that the layered structure on both sides of the dimming film layer 12 is asymmetric.

[0039] In this embodiment, since the film layer is made of polyvinyl butyral, the assembly process of the switchable glass is slightly different from that in Example 1. The assembly process of the switchable glass in this embodiment is as follows:

[0040] Step 1: First, clean the surfaces of the first transparent substrate 10 and the second transparent substrate 14 to ensure that they are free of dust, oil, or other impurities. Then, cut the third film layer 15 (polyvinyl butyral film) to the required dimensions of the first transparent substrate 10 and the second transparent substrate 14, ensuring that the polyvinyl butyral film is flat and free of any defects.

[0041] Step 2: Precisely place the polyvinyl butyral film and the dimming film 12 between the cleaned first and second transparent substrates 10, 14, ensuring that no bubbles exist between them and the first and second transparent substrates 10, 14. The assembled glass is then placed in a preliminary laminating machine, operating at a temperature of 110°C and a pressure of 0.1 MPa to achieve a preliminary bonding of the polyvinyl butyral film and the first and second transparent substrates 10, 14.

[0042] Step 3: Place the preliminarily bonded glass into a high-temperature autoclave, and ensure that the polyvinyl butyral film, the dimming film layer 12, the first transparent substrate 10, and the second transparent substrate 14 are completely bonded under the conditions of 130°C and 1 MPa.

[0043] Step 4: After the high temperature and high pressure treatment, the switchable glass needs to be cooled to ensure the stability of the laminated glass.

[0044] Step 5: The finished switchable glass undergoes a rigorous visual inspection to ensure it is free of bubbles, cracks, or other defects. Finally, the excess polyvinyl butyral film and the edges of the glass are trimmed off.

[0045] Example 3

[0046] Referring to FIG6 , this embodiment provides an asymmetric liquid crystal dimming glass. The asymmetric liquid crystal dimming glass includes a first transparent substrate 10, a first film layer 11, a dimming film layer 12, a second film layer 13, and a second transparent substrate 14, which are laminated and bonded together. The first film layer 11 and the second film layer 13 are composed of a third film layer 15. The first transparent substrate 10 is a 0.5 mm thick polycarbonate layer, and the surface of the first transparent substrate 10 has been hardened and waterproofed. The second transparent substrate 14 is a 2.1 mm thick tempered glass, and the third film is a 0.76 mm thick thermoplastic polyurethane elastomer film. The dimming film layer 12 is a dimming film based on a flexible substrate and made using liquid crystal technology. The first film layer 11 and the second film layer 13 both use a third film layer 15. In the dimming glass composed of the structure with the above thickness, the first film layer 11 and the second film layer 13 have the same thickness, and the thickness of the second transparent substrate 14 is greater than that of the first transparent substrate 10, ensuring that the layered structure on both sides of the dimming film layer 12 is asymmetric. The lamination process of the dimming glass in this embodiment is the same as the lamination process in Example 2. In this embodiment, by adopting an asymmetric design and thinning the glass on one side of the dimming film layer 12 or replacing it with a lightweight material such as polycarbonate, the weight of the overall structure is significantly reduced. For automotive applications, such a lightweight design can improve the fuel efficiency of fuel vehicles or extend the range of electric vehicle batteries.

[0047] Example 4

[0048] Referring to Figure 7, this embodiment proposes an asymmetric liquid crystal switchable glass. The asymmetric liquid crystal switchable glass comprises a first transparent substrate 10, a first film layer 11, a switchable film layer 12, a second film layer 13, and a second transparent substrate 14, which are laminated and bonded together. The first and second film layers 11 and 13 are formed by a third film layer 15. The first transparent substrate 10 is a 1mm thick polycarbonate layer, while the second transparent substrate 14 is a 3mm thick polycarbonate layer. The surfaces of the first and second transparent substrates 10 and 14 are hardened and waterproofed. The third film layer is a 0.60mm thick thermoplastic polyurethane elastomer film. The switchable film layer 12 is based on a flexible substrate and manufactured using liquid crystal technology. The first film layer 11 comprises one third film layer 15, while the second film layer 13 comprises two third film layers 15. This structure ensures that the layers on both sides of the switchable film layer 12 are asymmetric. The assembly process for the switchable glass in this embodiment is the same as that in Example 2.

[0049] It should be noted that the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0050] The above are only partial or preferred embodiments of the present application. Neither the text nor the drawings can limit the scope of protection of the present application. All equivalent structural transformations made using the contents of the present application specification and drawings under the overall concept of the present application, or direct / indirect application in other related technical fields are included in the scope of protection of the present application.

Claims

1. An asymmetric liquid crystal dimming glass, characterized in that: The asymmetric structure liquid crystal dimming glass includes a first transparent substrate, a first film layer, a dimming film layer, a second film layer and a second transparent substrate which are stacked and fixed together. The thickness of the first transparent substrate is less than or equal to 60% of the thickness of the second transparent substrate. The thickness range of the first transparent substrate is greater than or equal to 0.15 mm and less than or equal to 1.3 mm.

2. The asymmetric liquid crystal dimming glass according to claim 1, characterized in that: The thickness of the second film layer is greater than or equal to the thickness of the first film layer.

3. The asymmetric liquid crystal dimming glass according to claim 1, characterized in that: The thickness of the first film layer ranges from greater than or equal to 0.15 mm to less than or equal to 1.6 mm, and the thickness of the second film layer ranges from greater than or equal to 0.3 mm to less than or equal to 2.5 mm.

4. The asymmetric structure liquid crystal dimming glass according to claim 1, characterized in that: The thickness of the second transparent substrate is in the range of greater than or equal to 1.5 mm and less than or equal to 3 mm.

5. The asymmetric liquid crystal dimming glass according to claim 1, characterized in that: The second film layer is formed by stacking several third film layers with the same thickness.

6. The asymmetric liquid crystal dimming glass according to claim 1, characterized in that: The first film layer and the second film layer can exchange positions.

7. The asymmetric liquid crystal dimming glass according to claim 1, characterized in that: The first transparent substrate and the second transparent substrate are glass layers or transparent layers of flexible transparent optical materials.

8. The asymmetric liquid crystal dimming glass according to claim 1, characterized in that: The first film layer and the second film layer are one or more of ethylene-vinyl acetate copolymer, polyvinyl butyral, thermoplastic polyurethane elastomer, ionomer, and optically transparent adhesive material layer.

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