Polymer dispersed liquid crystal (PDLC) film edge sealing method

Abstract

The invention discloses a PDLC (Polymer Dispersed Liquid Crystal) film edge sealing method which comprises the following steps: firstly, carrying out semi-cutting pretreatment on the peripheral edge of a PDLC film to form an edge sealing step with a preset width; secondly, a matched edge sealing adhesive film pattern is cut according to the outline of the PDLC film, so that the edge sealing adhesive film accurately corresponds to the edge of the PDLC film; then, the cut edge sealing adhesive film pattern is attached to the edge of the PDLC film, and the edge sealing adhesive film pattern is rolled and compacted back and forth along the pre-fixing area through a roller; and finally, loading the pretreated PDLC film into a vacuum bag, laminating and compounding, and further curing. The edge sealing adhesive film is suitable for PDLC films in any shape and is not affected by the shape and camber of glass; firm and stable bonding is formed between the edge sealing adhesive film and the PDLC film through the synergistic effect of hot rolling pre-fixing and the high-temperature and high-pressure sheet combining technology, and the edge stripping phenomenon is effectively avoided; in addition, bubbles caused by dust can be avoided, and the bonding firmness and the bending resistance of the sealing edge are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of dimming films, and particularly relates to a method for sealing the edges of a PDLC film. Background Art

[0002] Dimming glass is a dimming product made by hot-pressing a polymer dispersed liquid crystal (PDLC) film and a film between two pieces of glass. Among them, the PDLC film undertakes the key function of dimming, and the adhesive layer plays a role in bonding. In order to meet specific performance requirements, most current dimming glasses are made by laminating with a polyvinyl butyral (PVB) film. The PVB adhesive contains a certain amount of plasticizer and other small additive molecules, which can effectively improve the cold resistance and heat resistance of the material. However, when the PDLC film and the PVB adhesive are hot-pressed into dimming glass under high temperature and high pressure, since the polymer dispersed liquid crystal layer in the PDLC film will be in direct contact with the PVB adhesive, the plasticizer and other small molecules in the PVB adhesive will gradually damage the structure of the PDLC film, making its foggy effect worse until it fails, resulting in the failure of some dimming areas and ultimately scrapping the entire product. Therefore, an effective method is needed to avoid direct contact between the PVB adhesive and the liquid crystal.

[0003] To solve the failure problem caused by the contact between the PVB adhesive and the liquid crystal, two main improvement schemes have been proposed in the current prior art, but both have obvious limitations. The first scheme is to apply a sealing adhesive to the four peripheral edges of the PDLC film, and after high-temperature curing, a solid covering layer is formed to block the contact between the PVB adhesive and the liquid crystal. However, this scheme has high requirements for the toughness of the sealing adhesive. When the toughness is insufficient, it is easy to break during transportation or in scenarios such as automotive sunroofs with large cambers; and strict requirements are placed on the cleanliness of the sealing step during operation, otherwise it is easy to cause poor bonding and colloid shedding. The second scheme is to use a double-layer polyethylene terephthalate (PET) tape to stick to the four peripheral edges of the PDLC film to block the contact between the PVB adhesive and the liquid crystal. However, this scheme has a complex process, requiring double-layer tapes to be pasted on the upper and lower sides, and parts of the adhesive need to be cut off at the four corners to prevent contact with the liquid crystal; and for irregular film pieces, especially those with a large curvature at the edge, since the adhesive position of the PET tape is fixed and cannot conform to the shape, wrinkles are likely to occur at the turning points, affecting the edge sealing quality; at the same time, the part where the two layers of edge-sealing tapes extend out of the film and are pasted on each other will occupy the width of the glass edge filling, bringing certain limitations to subsequent glass processing and assembly, and there is a high possibility of defects such as wrinkles and large deformations in the bonding of the two layers of edge-sealing tapes, affecting the edge sealing quality. Summary of the Invention

[0004] To address the problems in the traditional edge-sealing process of PDLC films, such as the risk of breakage caused by insufficient toughness of the edge-sealing glue, the strict cleaning requirements for the edge-sealing steps, the complex multi-layer adhesive structure, and the poor adaptability of the lamination process. This application proposes a PDLC film edge-sealing technology, which only uses a single-layer edge-sealing glue film at the four peripheral edges of the PDLC film. At the same time, the edge-sealing width of the edge-sealing glue film does not need to extend beyond the PDLC film sheet, and it is applicable to PDLC films of any shape, regardless of the shape and camber of the glass. Through the hot rolling pre-fixing process and the high-temperature and high-pressure curing and lamination process, a firm and stable bond is formed between the edge-sealing glue film and the PDLC film, effectively avoiding the edge peeling phenomenon, reducing the possibility of defects such as large deformations like wrinkles in the edge-sealing glue film, and improving the bonding firmness and bending resistance of the edge-sealing. The technical solutions provided in this application are as follows: On the one hand, this application provides a PDLC film edge-sealing method, including: Semi-cutting pretreatment: Perform semi-cutting pretreatment on the four peripheral edges of the PDLC film to form an edge-sealing step with a preset width; wherein, the cutting depth is to remove the upper base layer of the PDLC film; Edge-sealing glue film cutting: Based on the outer contour of the PDLC film, cut out an edge-sealing glue film pattern that matches the outer contour of the PDLC film from the edge-sealing glue film; Glue film positioning and pre-fixing: Attach the cut edge-sealing glue film pattern to the edge of the PDLC film, and use a roller to roll and preheat and compact along the pre-fixing area; wherein, the pre-fixing area is the area between the edge of the protective film and the edge of the upper base layer; Lamination and secondary curing: Laminate and combine the pretreated PDLC film and the glass substrate through a PVB interlayer film to form a sandwich structure, and then place the sandwich structure in a first autoclave for secondary curing at a preset temperature and a preset pressure; or, After loading the pretreated PDLC film into a vacuum bag, place it in a second autoclave for initial curing under the negative pressure generated by vacuum pumping and the cooperation of the second autoclave; then laminate and combine the cured PDLC film and the glass substrate with a PVB interlayer film to form the sandwich structure, and place the sandwich structure in the first autoclave for further curing at a preset temperature and a preset pressure.

[0005] In some specific embodiments, the operating temperature of the roller is 90 - 120 °C, the rolling speed is 0.5 - 6 m / min, and the pressure applied to the pre-fixing area is 10 - 30 N.

[0006] In some specific embodiments, the preset temperature is 125 - 145 °C, and the preset pressure is 0.8 - 1.1 MPa.

[0007] In some specific embodiments, the size of the protective film is smaller than that of the upper base layer, and its thickness is 20 - 80 μm.

[0008] In some specific embodiments, when the roller operates, the distance between the roller and the edge of the upper base layer and the edge of the protective film is 0.1 mm - 1 mm; The ratio of the width of the pre - fixing area to the width of the edge - sealing step is (1.01 - 1.6):1.

[0009] In some specific embodiments, the width of the pre - fixing area is 2 - 50 mm, and the width of the edge - sealing step is 1 - 70 mm.

[0010] In some specific embodiments, the edge - sealing adhesive film includes a base material layer and an adhesive coated on the surface of the base material layer; The material of the base material layer is selected from one or more of polyethylene terephthalate, polyimide; The semi - curing temperature of the adhesive is 90 - 110 °C; The adhesive is selected from epoxy resin adhesive systems.

[0011] In some specific embodiments, the thickness of the base material layer is 20 - 95 μm; The thickness of the epoxy resin adhesive layer is 5 - 80 μm.

[0012] In some specific embodiments, the thickness of the edge - sealing adhesive film is 25 - 100 μm; The thickness of the PVB interlayer film is 0.38 - 1.52 mm.

[0013] In some specific embodiments, the horizontal distance from the edge of the protective film to the edge of the lower base layer is 5 - 20 mm.

[0014] In some specific embodiments, when the roller operates, the contact surface width between it and the pre - fixing area is 3 - 15 mm.

[0015] Adopting the above - mentioned technical solutions, a PDLC film edge - sealing method provided by the present application has the following beneficial effects: The present application selects epoxy resin adhesive film, etc. as the edge - sealing material. This material will not chemically react with liquid crystal, thus effectively preventing the problem of the failure of the dimming area in the subsequent lamination process of the PDLC film; The process of the present application is simple, and only a single - layer edge - sealing adhesive film is needed to complete the edge - sealing operation. Moreover, the edge - sealing width does not need to extend beyond the PDLC film sheet, avoiding the cumbersome processes of additional cutting and precise control of the edge - sealing width, and further improving the convenience of construction.

[0016] Through the synergistic effect of the hot rolling pre-fixation and the high-temperature and high-pressure curing lamination process, the different regions of the edge-sealing adhesive film are processed step by step in two steps, enabling the edge-sealing adhesive film to firmly adhere to the PDLC film, effectively avoiding the edge peeling phenomenon, reducing the possibility of defects such as large deformations like wrinkles in the edge-sealing adhesive film, and improving the bonding firmness and bending resistance of the edge sealing. Among them, the hot rolling pre-fixation process preliminarily fixes the position of the edge-sealing adhesive film, making it closely combined with the PDLC film, facilitating transportation and avoiding displacement during handling; the high-temperature and high-pressure curing lamination process further enhances the bonding strength between the two, making the edge-sealing effect stable and lasting, improving the bonding firmness and bending resistance of the edge sealing, and reducing the risk of edge peeling.

[0017] The entire surface of the edge-sealing adhesive film used in this application is covered with glue, and the corresponding edge-sealing adhesive film pattern can be cut out according to the PDLC film of any shape to meet the requirements of different scenarios and design schemes. Whether it is a regular rectangle or an irregular special shape, the pre-fixation and edge-sealing operations can be realized, expanding the application scope of this technology and enabling it to play a role in the encapsulation of different types of PDLC films. Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a schematic diagram of the pre-fixation stage of the PDLC film edge-sealing method provided by the embodiment of the present application; Figure 2 It is a schematic diagram of the secondary curing stage of the PDLC film edge-sealing method provided by the embodiment of the present application Figure 1 ; Figure 3 It is a schematic diagram of the secondary curing stage of the PDLC film edge-sealing method provided by the embodiment of the present application Figure 2 ; Figure 4 It is a schematic diagram of the edge-sealing adhesive film and the cut edge-sealing adhesive film pattern provided by the embodiment of the present application.

[0020] The following is a supplementary description of the drawings: 11 - Upper base layer; 12 - Lower base layer; 2 - Polymer dispersed liquid crystal layer; 3 - Protective film; 4 - Edge-sealing adhesive film; 41 - Substrate layer; 42 - Adhesive; 5 - Silver paste; 6 - PVB interlayer film; 71 - Pre-fixation area; 72 - Edge-sealing step; 8 - Roller; 10 - Vacuum bag; 101 - Air extraction nozzle. Detailed Description of the Specific Embodiment

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0022] As used herein, the term "one embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that can be included in at least one implementation of the present application. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0023] When a numerical range is disclosed herein, the above range is considered continuous and includes the minimum and maximum values of the range, as well as each value therebetween. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein. For example, the specified range from "1 to 10" should be considered to include any and all sub-ranges between the minimum value 1 and the maximum value 10. Exemplary sub-ranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0024] Please refer to Figures 1 to 4 , the PDLC film edge sealing method provided by the embodiments of the present application includes: Semicutting pretreatment: performing semicutting pretreatment on the four peripheral edges of the PDLC film to form a sealing edge step 72 with a preset width; wherein, the cutting depth is to remove the upper base layer 11 of the PDLC film; Edge-sealing film cutting: Based on the outer contour of the PDLC film, the edge-sealing film 4 is cut into an edge-sealing film pattern that matches the outer contour of the PDLC film; Film positioning and pre-fixing: The cut edge-sealing film pattern is attached to the edge of the PDLC film, and a roller 8 is used to roll and preheat and compact it along the pre-fixing area 71; among them, the pre-fixing area 71 is the area between the edge of the protective film 3 and the edge of the upper base layer 11; Lamination and secondary curing: The pretreated PDLC film and the glass substrate are laminated through the PVB interlayer film 6 to form a sandwich structure, and then the sandwich structure is placed in an autoclave and subjected to secondary curing at a preset temperature and a preset pressure; Or, after the pretreated PDLC film is loaded into the vacuum bag 10, it is placed in a second autoclave and initially cured under the negative pressure generated by vacuum pumping and the cooperation of the second autoclave; then the cured PDLC film and the glass substrate are laminated through the PVB interlayer film 6 to form a sandwich structure, and the sandwich structure is placed in a first autoclave and further cured under preset temperature and preset pressure conditions.

[0025] Specifically, the structure of the PDLC film is usually composed of two layers of transparent conductive materials (the upper base layer 11 and the lower base layer 12 respectively) sandwiching the polymer-dispersed liquid crystal layer 2. The upper and lower base layers serve as carriers of the conductive layer, and a PET protective film 3 is usually attached to the surface to prevent abrasion and scratches, and this protective film 3 is removed before the final lamination; a silver paste 5 is coated on the surface of the conductive layer to form an electrode for realizing electrical signal transmission. The non-electrode layer structure and the edge-sealing process are the same but do not require coating with silver paste 5; the polymer-dispersed liquid crystal layer 2 serves as the main body of the dimming function, and the arrangement direction of the liquid crystal droplets is changed by applying an external electric field to control light scattering or transmission, but special attention needs to be paid to the plasticizer in the PVB interlayer film 6, because its contact with the liquid crystal will cause the liquid crystal to dissolve or phase separate, thereby causing the problem of dimming failure. During the edge-sealing process, first, the PDLC film is placed flat on the workbench, and the four edges of the PDLC film are semi-cut and pretreated by using a high-precision laser cutting or numerical control milling process, and the upper base layer 11 is accurately removed to form a sealing edge step structure with a preset width. The exposed lower base layer 12 can be made into a transparent electrode or the local liquid crystal can be completely removed as needed to form an active bonding surface. The preset width of this sealing edge step 72 can be adjusted according to the width of the pre-fixing area 71. Generally, the width of the pre-fixing area 71 is greater than the width of the sealing edge step 72 to reduce the risk of wrinkles or glue overflow during the pre-fixing of the edge-sealing film 4.

[0026] Secondly, customize and cut the edge-sealing film pattern according to the outer contour of the PDLC film. Please refer to Figure 4, in the figure, the left rectangle represents the uncut complete edge-sealing adhesive film 4, the figure in the middle represents the required edge-sealing adhesive film pattern cut out on the complete edge-sealing adhesive film 4 according to the shape of different PDLC films, and the figure on the right represents the cut edge-sealing adhesive film pattern adhered to the edge of the PDLC film. Since the edge-sealing adhesive film 4 is a whole-surface covering adhesive, when pasted on a large-arc chamfer, no folding or twisting operations are required, and it only needs to be placed on the PDLC film, which solves the pain point of the large rounded corner not being able to be edge-sealed in the existing second solution and adapts to PDLC films of various shapes. At the same time, in the design of the edge-sealing adhesive film 4, large straight edges can be not adopted, but more curved-edge styling designs can be used to adapt to glass with a larger arch height. A parametric curved-edge styling scheme can be adopted to achieve geometric matching with the high-arch glass through CAD / CAM collaborative design, improving the adaptability flexibility of the edge-sealing adhesive film.

[0027] Subsequently, the cut edge-sealing adhesive film pattern is accurately positioned to the target area, and a constant-temperature roller 8 is used to carry out a rolling hot compaction operation along the pre-fixed area 71, that is, the limited interval between the edge of the protective film 3 and the edge of the upper base layer, to ensure the initial stable adhesion of the edge-sealing adhesive film 4. The surface temperature of the roller 8 during operation can be controlled in the range of 90 - 120 °C, the rolling speed is controlled in the range of 0.5 - 6 m / min, and the downward pressure is controlled in the range of 10 - 30 N. This rolling heating mode realizes the layer-by-layer curing of the bonding area through a gradient thermal field, which not only ensures the interfacial bonding strength between the upper base layer 11 and the edge-sealing adhesive film 4, but also realizes the successive heating, bonding and curing, and cooling of the bonding area through the rolling heating method, reducing defects such as wrinkles in the bonding area, improving the bonding strength, and at the same time, the successive heating and cooling also reduce the thermal influence on the non-bonding area in the pre-curing stage, which is beneficial to reducing defects such as excessive deformation of the non-bonding area of the adhesive film and premature curing resulting in reduced adhesiveness during the subsequent high-temperature curing bonding. At this time, a gap is left at the corresponding part of the edge-sealing step 72 in the non-bonding area during the pre-curing stage, which is beneficial to the discharge of air bubbles generated in the pre-fixed area 71, thereby further reducing the quality impact caused by the remaining air bubbles in the finished product.

[0028] Finally, PVB interlayer 6 is used for lamination and encapsulation. After the outer glass layer, the dimming functional layer (including the PDLC film assembly), and the inner glass layer are grouped in sequence, they are placed in an autoclave for high-temperature and high-pressure treatment. Please refer to Figure 2 , where the arrow in the figure represents the downward pressure generated by the PVB interlayer 6 on the edge-sealing adhesive film 4. During this process, the edge-sealing adhesive film 4 of the lower base layer 12 is cured under the high-temperature and high-pressure environment and the extrusion of the PVB interlayer 6; the adhesive film in the pre-fixed area 71 is subjected to secondary hot-pressing and curing, further improving the bonding stability, effectively preventing the physical contact or chemical migration between the PVB interlayer 6 and the liquid crystal medium, and achieving a good edge-sealing effect.

[0029] In some specific embodiments, the preset temperature is 125 - 145 °C and the preset pressure is 0.8 - 1.1 MPa. High temperature and high pressure are conducive to the rapid heat melting of the PVB interlayer film 6 during the lamination process and ensure the downward pressure on the edge-sealing adhesive film 4, thereby facilitating the reduction of the gap between the PET section and the adhesive film during the edge-sealing process and minimizing the adverse effects brought by the gap.

[0030] Or, please refer to Figure 3 , before the lamination and composite process, first load the pretreated PDLC film into the vacuum bag 10 and then transfer it to the second autoclave for initial curing treatment. By establishing a negative pressure environment through the air extraction nozzle 101 and combining with the airtight pressurization conditions of the second autoclave, the edge-sealing adhesive film is fully cured before leaving the factory and forms a stable bond with the PDLC film. It can effectively prevent the silver paste 5 or the lower base layer 12 from adsorbing dust and impurities due to environmental exposure during transportation, thereby avoiding bubble defects caused by impurity inclusion during the secondary lamination. By evacuating the vacuum bag 10, it is conducive to the atmospheric pressure to ensure the downward pressure on the edge-sealing adhesive film 4, thereby facilitating the reduction of the gap between the PET section and the adhesive film during the edge-sealing process and minimizing the adverse effects brought by the gap.

[0031] In some specific embodiments, the operating temperature of the roller 8 is 90 - 120 °C, the rolling speed is 0.5 - 6 m / min, and the pressure applied to the edge-sealing adhesive film 4 is 10 - 30 N.

[0032] Specifically, under the process conditions of relatively low temperature (90 - 120 °C) and relatively high speed (0.5 - 6 m / min), by adopting a rolling heating and pressurizing curing method for the pre-fixed area 71, the bonding strength between the upper base layer 11 and the edge-sealing adhesive film 4 can be effectively improved. The rolling heating method enables the bonding area to achieve successive heating, bonding, curing, and cooling, which helps to reduce defects such as wrinkles in the bonding area and improve the bonding strength. Moreover, the successive heating and cooling processes can reduce the heat influence on the non-bonding area during the pre-curing stage and reduce defects such as reduced bonding caused by excessive deformation and premature curing of the adhesive film in this area. In addition, the 10 - 30 N pressure applied to the edge-sealing adhesive film 4 can ensure the tight fit of the adhesive film with the PET substrate, exclude air and gaps between the interfaces, make the glue layer evenly distributed, avoid local lack of glue or excessive thickness, and the appropriate pressure can promote the fluidity and wettability of the colloid, enhance the interfacial bonding effect between the adhesive film and the PET substrate and the edge-sealing adhesive film 4, and further improve the stability and tightness of the overall structure, preventing problems such as delamination and degumming during use. After this pre-fixing, the peel strength between the upper base layer 11 and the edge-sealing adhesive film 4 can reach 0.07 - 0.2 N / m, which can ensure that the adhesive film will not fall off during the subsequent processes and transportation.

[0033] In some specific embodiments, the size of the protective film 3 is smaller than that of the upper base layer 11, and its thickness is 20 - 80 μm.

[0034] Specifically, since the PDLC film has extremely high requirements for appearance, any friction scratches are strictly prohibited in the visible area. A PET protective film 3 with a preferred thickness of usually 50 μm is laminated on its surface to ensure that the appearance of the dimming area is flawless. The size of the protective film 3 is slightly smaller than that of the upper base layer 11, and the uncovered area is used to bond the edge-sealing adhesive film 4, which can not only prevent the edge-sealing adhesive film 4 from falling off but also ensure that the peel strength meets the process requirements. Finally, the protective film 3 is torn off before lamination to ensure the appearance integrity of the PDLC film and achieve reliable edge sealing.

[0035] In some specific embodiments, when the roller 8 operates, the distance from the edge of the upper base layer 11 and the edge of the protective film 3 is 0.1 mm - 1 mm; The width ratio of the pre-fixing area 71 to the edge-sealing step 72 is (1.01 - 1.6):1.

[0036] Specifically, when the roller 8 operates, the distance from the edge of the upper base layer 11 and the edge of the protective film 3 is controlled between 0.1 mm and 1 mm, which can further reduce the thermal influence. If the right side of the roller 8 exceeds this distance range, it will cause excessive deformation at the half-cut edge-sealing step 72, which will have an adverse impact on the product quality; if the left side of the roller 8 exceeds the boundary of the edge-sealing adhesive film 4, the glue may not be pressed on the edge, resulting in poor adhesion and may also cause problems such as warping.

[0037] In addition, the width ratio of the pre-fixing area 71 to the edge-sealing step 72 is (1.01 - 1.6):1. By limiting the width of the pre-fixing area 71 to be larger, the suspended area during pre-fixing can be reduced, which is conducive to reducing the possibility of defects such as wrinkles in the adhesive film during pre-fixing.

[0038] In some specific embodiments, the width of the pre-fixing area 71 is 2 - 50 mm, optionally 2 - 15 mm, and the width of the edge-sealing step 72 is 1 - 70 mm, optionally 1 - 20 mm.

[0039] In some specific embodiments, the edge-sealing adhesive film 4 includes a substrate layer 41 and an adhesive 42 coated on the surface of the substrate layer 41. The edge-sealing adhesive film 4 is mainly composed of the substrate layer 41 and the adhesive 42 coated on its surface. It can provide good bonding strength in the pre-fixing area during pre-fixing, and at the same time, in the non-pre-fixing area 71, it provides a certain ability to maintain a stable shape and suitable anti-deformation ability (preventing defects such as excessive deformation and wrinkles due to heat), so that one end of the edge-sealing adhesive film 4 can be fixed to the upper base layer 11 for pre-bonding, and the other end maintains the free shrinkage characteristic.

[0040] The material of the substrate layer 41 is selected from one or more of polyethylene terephthalate (PET) and polyimide (PI). The substrate layer 41 can be selected from one or more of high-strength polymer polymers such as PET or PI, and its high modulus characteristics can effectively enhance the mechanical bearing capacity of the adhesive film.

[0041] The semi-curing temperature of the adhesive 42 is 90 - 110 °C; selecting an appropriate semi-curing temperature of the adhesive 42 is beneficial to the bonding of the edge-sealing adhesive film 4 during the film positioning and pre-fixing stage and to generate sufficient bonding strength during roll pressing and heating; The adhesive 42 is selected from the epoxy resin adhesive system. The epoxy resin adhesive system (such as toughened and high-temperature cured epoxy adhesives, anhydride-promoted epoxy adhesives) is selected for the adhesive 42, and its bonding performance is activated under a specific hot pressing process to achieve a stable combination with the upper and lower base layers.

[0042] In some specific embodiments, the thickness of the substrate layer 41 is 20 - 95 μm; The thickness of the epoxy resin adhesive system layer is 5 - 80 μm.

[0043] Specifically, the thickness of the substrate layer 41 of the edge-sealing adhesive film 4 is between 20 - 95 μm. It serves both as a carrier for the adhesive 42 and as a barrier to prevent the PVB interlayer 6 from contacting the liquid crystal. Since the periphery of the PDLC film needs to be edge-sealed to completely isolate external substances, there are at least two overlapping points of the edge-sealing adhesive film 4. If the thickness of the substrate layer 41 is too thick, voids will appear at the overlapping part, forming a channel for plasticizer to invade the liquid crystal. As a carrier for the adhesive 42, an appropriate thickness can provide support for the edge-sealing adhesive film 4 during half-side pre-fixing bonding, and at the same time prevent excessive deformation of the part outside the pre-fixing area 71 due to thermal influence; if the thickness is too thin, it is difficult to resist the thermal influence outside the pre-fixing area 71 and cause excessive deformation; while if the thickness is too large, the covering gap of the part outside the pre-fixing area 71 will be too large and it is not easy to deform, making it difficult to meet the actual application requirements.

[0044] In the adhesive 42 process, the thickness of the epoxy resin adhesive system layer is controlled within the range of 5 - 80 μm. The pre-curing of the adhesive 42 process is carried out by a hot roller 8, and complete curing is achieved during the lamination process, or curing is achieved by heating under vacuum and complete curing is achieved during the lamination process, so as to block the channel between the edge-sealing adhesive film 4 and the upper base layer 11. For the epoxy resin adhesive system, if the adhesive layer is too thick, it is easy to cause the problem of glue overflow, while if the thickness is too low, the bonding stability will be poor. Therefore, in order to balance the support performance and the bonding effect, it is more appropriate to control the adhesive layer thickness within the range of 5 - 80 μm.

[0045] In some specific embodiments, the thickness of the edge-sealing adhesive film 4 is 25-100 μm. Specifically, the overall thickness of the edge-sealing adhesive film 4 is controlled between 25-100 μm. If the thickness of the edge-sealing adhesive film 4 is too high, a step will be formed at its starting point when bonding with the PDLC film. During the subsequent lamination process, the external extrusion will cause stress concentration. After a certain period of time, this stress concentration area is extremely likely to form indentations on the PDLC film, and in severe cases, it may even cause the conductive layer of the PDLC film to break. On the contrary, if the thickness of the edge-sealing adhesive film 4 is too low, the thickness of the substrate layer 41 and the adhesive 42 cannot be reasonably distributed, thereby affecting the performance and stability of the entire film structure.

[0046] The thickness of the PVB interlayer film 6 is 0.38-1.52 mm. Preferably, the thickness of the PVB interlayer film 6 is 0.38 mm, 0.76 mm, 1.14 mm or 1.52 mm, and 0.38 mm is preferred in automotive dimming skylights.

[0047] In some specific embodiments, the horizontal distance from the edge of the protective film 3 to the edge of the lower base layer 12 is 5-20 mm. This distance is greater than the edge-sealing width, which can effectively prevent the edge-sealing adhesive film 4 from adhering to the protective film 3 during the lamination process, thereby ensuring the lamination accuracy and stability of the entire film layer structure, and preventing a series of situations such as poor lamination, appearance defects, and possible performance problems during subsequent use caused by the edge-sealing adhesive film 4 sticking to the protective film 3.

[0048] In some specific embodiments, when the roller 8 is operating, the contact surface width between it and the pre-fixed area 71 is 3-15 mm. When the roller 8 is operating, it cannot shift to the position of the protective film 3, ensuring that the roller 8 completely covers the contact surface with the edge-sealing adhesive film 4, and the width range is between 3-15 mm. If the width is too small, it cannot provide reliable peel strength, and if the width is too large, it will exceed the half-cut of the film sheet, which is meaningless.

[0049] The edge sealing method of the PDLC film disclosed in this application uses an edge sealing adhesive film composed of a substrate layer 41 and an adhesive 42 with a suitable thickness, which can provide good bonding strength in the pre-fixed bonding area 71 during pre-fixed bonding, and at the same time can provide a certain ability to maintain a stable shape in the non-pre-fixed area during pre-fixed bonding, and has a suitable anti-deformation ability (to avoid excessive deformation due to heat and defects such as wrinkles in the adhesive film); adopting the above method of pre-fixed bonding one end to the base layer 11 and the other end being non-fixed and freely contractible, and at the same time having a suitable thickness and a suitable anti-deformation ability, during the lamination process or the vacuum curing process, under high temperature and high pressure environment, during the pressing process of the PVB interlayer film 6 or during the pressing process of the atmospheric pressure in the vacuum bag, the other end has a non-fixed and freely contractible method, and has a suitable deformability (for example, at this time, the edge sealing adhesive film is deformed under a greater force under the support and pressing of the PVB interlayer film 6 or the edge sealing adhesive film is deformed under a greater force under the support of the vacuum bag and the atmospheric pressure, which can make the edge sealing adhesive film controllably deformed and bonded and cured with the silver paste 5 or the lower base layer 12, so as to avoid defects such as wrinkles in the adhesive film, without the need to bond and seal the edges through two upper and lower adhesive films), and has a better edge sealing effect.

[0050] The above are only optional embodiments of this application and are not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included in the protection scope of this application.

Claims

1. A method for sealing the edge of a PDLC film, characterized in that, Including: Semi-cut pretreatment: Perform semi-cut pretreatment on the four peripheral edges of the PDLC film to form a sealing edge step (72) with a preset width; wherein, the cutting depth is to remove the upper base layer (11) of the PDLC film; Edge-sealing adhesive film cutting: Based on the outer contour of the PDLC film, cut out an edge-sealing adhesive film pattern that matches the outer contour of the PDLC film from the edge-sealing adhesive film (4); Adhesive film positioning and pre-fixing: Attach the cut edge-sealing adhesive film pattern to the edge of the PDLC film, and use a roller (8) to roll and preheat and compact it along the pre-fixing area (71); wherein, the pre-fixing area (71) is the area between the edge of the protective film (3) and the edge of the upper base layer (11); Lamination and secondary curing: Laminate and combine the pretreated PDLC film and the glass substrate through a PVB interlayer film (6) to form a sandwich structure, and then place the sandwich structure in a first autoclave for secondary curing at a preset temperature and a preset pressure; or, After loading the pretreated PDLC film into a vacuum bag (10), place it in a second autoclave for initial curing under the negative pressure generated by vacuum pumping and the cooperation of the second autoclave; then laminate and combine the cured PDLC film and the glass substrate with a PVB interlayer film (6) to form the sandwich structure, and place the sandwich structure in the first autoclave for further curing under preset temperature and pressure conditions.

2. The PDLC film edge sealing method according to claim 1, wherein, The operating temperature of the roller (8) is 90 - 120 °C, the rolling speed is 0.5 - 6 m / min, and the pressure applied to the pre-fixing area (71) is 10 - 30 N.

3. The PDLC film edge sealing method according to claim 1, wherein The preset temperature is 125 - 145 °C, and the preset pressure is 0.8 - 1.1 MPa.

4. The PDLC film edge-sealing method according to claim 1, characterized in that The size of the protective film (3) is smaller than the size of the upper base layer (11), and its thickness is 20 - 80 μm.

5. The PDLC film edge sealing method according to claim 1, wherein, When the roller (8) operates, the distance from the edge of the upper base layer (11) and the edge of the protective film (3) is 0.1 mm - 1 mm; the width ratio of the pre-fixing area (71) to the width of the sealing edge step (72) is (1.01 - 1.6):

1.

6. The PDLC film edge sealing method according to claim 1, wherein The width of the pre-fixing area (71) is 2 - 50 mm, and the width of the sealing edge step (72) is 1 - 70 mm.

7. The edge sealing method of the PDLC film according to claim 1, wherein, The edge-sealing adhesive film (4) includes a base material layer (41) and an adhesive (42) coated on the surface of the base material layer (41); The material of the base material layer (41) is selected from one or more of polyethylene terephthalate and polyimide; The semi-curing temperature of the adhesive (42) is 90 - 110 °C; The adhesive (42) is selected from epoxy resin adhesive systems.

8. The edge sealing method of the PDLC film according to claim 7, wherein The thickness of the base material layer (41) is 20 - 95 μm; The thickness of the epoxy resin adhesive system layer is 5 - 80 μm.

9. The edge sealing method of the PDLC film according to claim 1, characterized in that, The thickness of the edge-sealing adhesive film (4) is 25 - 100 μm; The thickness of the PVB interlayer film (6) is 0.38 - 1.52 mm.

10. The PDLC film edge sealing method according to claim 1, characterized in that, The horizontal distance from the edge of the protective film (3) to the edge of the lower base layer (12) is 5 - 20 mm.

11. The method for sealing the edge of the PDLC film according to claim 1, wherein, When the roller (8) is operating, the width of the contact surface between it and the pre-fixed area (71) is 3 - 15 mm.

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