An integrated power-off privacy (PDLC) light control film and a preparation method thereof

Abstract

The application discloses an integrated power-off privacy PDLC dimming film and a preparation method thereof. The dimming film comprises a first transparent conductive layer, a polymer dispersed liquid crystal layer and a second transparent conductive layer in sequence. The visible side surface of the polymer dispersed liquid crystal layer is provided with a microstructure composed of protrusions with a height of 3-7 microns and grooves with a width of 3-7 microns and a center line distance between adjacent grooves of 8-12 microns. When powered on, the polymer dispersed liquid crystal layer is in a transparent state, realizing clear and full-view angle visibility. When powered off, the polymer dispersed liquid crystal layer is in a fog state, realizing a privacy effect of only normal angle visibility and oblique angle invisibility in combination with the surface microstructure. The integrated structure does not need an additional composite privacy film, avoiding problems such as high-temperature delamination, uneven light scattering, interlayer refractive loss and interface defects caused by material thermal expansion differences in the traditional composite structure. Meanwhile, the traditional PDLC needs to be powered on for a long time to realize privacy, which affects the service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical functional film materials, and particularly relates to an integrated power-off privacy PDLC light modulation film and a preparation method thereof. BACKGROUND

[0002] A conventional PDLC (Polymer Dispersed Liquid Crystal) privacy film usually adopts a structure design of combining an independent privacy film under a PDLC film. However, the combined structure has significant technical defects: on the one hand, due to the difference in material expansion coefficients between the privacy film and the PDLC film, delamination or uneven light scattering is prone to occur in a high-temperature environment; on the other hand, the superposition of multiple layers of materials causes interlayer refraction loss, reducing the overall privacy efficiency; in addition, the additional privacy film layer needs to be combined through complex processes such as adhesion, which not only has a complicated process and a large number of interfaces, but also is prone to interlayer defects, affecting the stability of display effect and privacy performance, and the PDLC film needs to be powered for a long time to achieve the privacy function, while the privacy state is more frequent in actual use, and long-time power-on not only increases energy consumption, but also significantly affects the service life. At the same time, the condensing process of the existing PDLC light modulation film usually uses an ordinary smooth coating wheel for coating, so that the PDLC material is uniformly laid on the substrate to form a flat film layer, but such a film layer lacks effective light guiding and condensing structure, resulting in serious scattering of light in the film layer, energy dispersion, and low condensing efficiency, which is difficult to meet the actual demand for light intensity and concentration in application scenarios such as display devices and lighting devices. SUMMARY

[0003] The present application provides an integrated power-off privacy PDLC light modulation film to solve the problems of delamination at high temperature, uneven light scattering, interlayer refraction loss, complex process, and long-time power-on affecting the service life of the conventional PDLC privacy film caused by the combination of an independent privacy film under the PDLC film, and the like. The microstructure of a height of 3-7 μm, a width of 3-7 μm, and a pitch of 8-12 μm is arranged on the visible side surface of the PDLC layer. When powered on, the PDLC is transparent to realize full-view visibility, and when powered off, the PDLC is in a fog state to realize normal-view visibility and oblique-view privacy in cooperation with the microstructure. The integrated power-off privacy PDLC light modulation film does not need to be combined with a privacy film, avoids material defects and complex process, simplifies the process, and improves the privacy efficiency, display stability, and service life. The technical scheme provided by the present application is as follows:

[0004] In one aspect, the present application provides an integrated power-off privacy PDLC light modulation film, comprising:

[0005] a first transparent conductive layer;

[0006] a second transparent conductive layer;

[0007] a polymer dispersed liquid crystal layer, which is arranged between the first transparent conductive layer and the second transparent conductive layer; a visible side surface of the polymer dispersed liquid crystal layer is provided with a microstructure, the microstructure includes protrusions and grooves, the height of the protrusions is 3-7 μm, the width of the grooves is 3-7 μm, and the center line distance between adjacent two grooves is 8-12 μm; wherein the visible side is the side away from the light source;

[0008] The polymer dispersed liquid crystal layer is in a transparent state in an energized state and is in a privacy state in a de-energized state.

[0009] In some specific embodiments, the groove shape of the microstructure is selected from one of an elongated shape, a triangular shape or a semicircular shape; wherein the protrusions are formed between adjacent grooves.

[0010] In some specific embodiments, when applied to a 5-12 inch display screen, the groove shape is a triangular shape;

[0011] When applied to a 13-29 inch display screen, the groove shape is an elongated shape;

[0012] When applied to a 30-120 inch display screen, the groove shape is a semicircular shape.

[0013] In some specific embodiments, when the groove is an arc-shaped surface of a semicircular shape, the bottom height of the groove is 0.5-1 μm; the bottom height of the groove is the difference between the depth of the groove and the total height of the protrusion.

[0014] In some specific embodiments, the top angle of the triangular groove ranges from 30° to 50°.

[0015] In some specific embodiments, the grooves and protrusions of the polymer dispersed liquid crystal layer only allow vertical light to pass through in a de-energized state, and the side viewable range is less than 30°.

[0016] In another aspect, the application also provides a preparation method of an integrated de-energized privacy PDLC light control film, including the following steps:

[0017] Transparent conductive layer preparation: continuously conveying the first transparent conductive layer and the second transparent conductive layer through the unwinding wheels respectively;

[0018] Polymer dispersed liquid crystal layer coating: placing the polymer dispersed liquid crystal material in the liquid crystal tank 22, and performing directional coating on the polymer dispersed liquid crystal material through the coating wheel 24 provided with a regular arrangement structure on the surface;

[0019] Coating control: the polymer dispersed liquid crystal material after coating is scraped and leveled by a scraper, so that the polymer dispersed liquid crystal material is uniformly coated and transferred to the surface of the first transparent conductive layer and has a microstructure;

[0020] Preliminary curing: the first transparent conductive layer coated with the polymer dispersed liquid crystal material is pre-cured by a UV curing lamp;

[0021] Laminating treatment: the second transparent conductive layer is aligned and laminated with the first transparent conductive layer by a matching wheel, and is pressed by a pressing wheel, so that the polymer dispersed liquid crystal layer is preliminarily anchored between the first transparent conductive layer and the second transparent conductive layer;

[0022] Baking curing: the laminated first transparent conductive layer and the second transparent conductive layer are baked;

[0023] Cooling treatment: the baked first transparent conductive layer and the second transparent conductive layer are cooled;

[0024] Rolling forming: rolling is completed by a rolling wheel, and an integrated power-off privacy PDLC light modulation film is prepared, and the polymer dispersed liquid crystal layer of the light modulation film has a regular arrangement of protrusions and grooves formed by the microstructure of the coating wheel 24 on the visible side.

[0025] In some specific embodiments, the scraping pressure of the scraper during scraping is 0.1-0.5 MPa, and the scraping angle is 0°-80°.

[0026] In some specific embodiments, the pressing pressure of the pressing wheel during pressing is 0.1-0.7 MPa, and the pressing speed is 1-10 m / min.

[0027] In some specific embodiments, the radiation energy of the UV curing lamp during curing is 5-100 mW / cm 2 , and the irradiation time is 3-20 s;

[0028] During baking curing, the baking temperature is 50-150 ℃, and the baking time is 5-60 min.

[0029] By adopting the technical solutions, the integrated power-off privacy PDLC light modulation film and the preparation method thereof provided by the present application have the following beneficial effects:

[0030] 1. Through the direct rolling process, grooves and convex structures are physically formed on the surface of the polymer dispersed liquid crystal layer, without the need for an additional privacy film layer under the polymer dispersed liquid crystal layer, thereby saving the adhesion process (such as glue coating and pressing) of the traditional multi-layer composite structure, reducing the overall thickness of the privacy and dimming layer, reducing material and production costs, and improving the flexibility of the film material by reducing the thickness of the film layer and the stress buffering characteristics of the structure; at the same time, the integrated design of the one-piece microstructure avoids the delamination risk and process complexity of the traditional composite multi-layer film, and is suitable for more application scenarios.

[0031] 2. Due to the difference in the expansion coefficient between the privacy film and the polymer dispersed liquid crystal layer, the traditional composite structure is prone to delamination, peeling or uneven light scattering in a high-temperature environment; the present scheme directly integrates microstructures through a single polymer dispersed liquid crystal layer, without multiple composite interfaces, thereby completely avoiding the delamination risk caused by material thermal expansion mismatch, and the one-piece grooves and convex structures enhance the overall stress buffering capacity of the film layer, thereby improving the durability and long-term stability of the film material.

[0032] 3. By directly rolling the microstructure (convex height 3 ~ 7 μm, groove width 3 ~ 7 μm, and adjacent groove center line spacing 8 ~ 12 μm) of a specific size on the visible side surface of the polymer dispersed liquid crystal layer, the high haze characteristic of the PDLC layer when not powered is utilized, the thickness is reduced at the groove due to the high haze characteristic of the PDLC film when not powered, thereby ensuring the transmission of light in the vertical direction and the near-vertical direction, thereby realizing the formation of a PDLC region that is approximately a grating on the top or near the top of the convex without the need for a grating film; in the non-vertical direction, due to the high haze characteristic of the PDLC film when not powered, the thickness increases, and the grooves and convexes block the reflection and refraction of light, thereby achieving light blocking in the non-vertical direction and achieving better privacy effect, thereby facilitating the reduction of the thickness of the privacy and dimming layer through the structure; the PDLC region with approximately grating effect is formed without the need for an additional grating film, realizing the flexible switching of precise privacy (off-state side visible range < 30°, haze > 90%) and transparent sharing (on-state haze < 5%, close to improved PDCLC level).

[0033] 4. The traditional scheme relies on long-term power supply of the polymer dispersed liquid crystal layer to achieve the privacy effect, but the privacy state is actually used more frequently, and long-term power supply can accelerate the aging of the polymer dispersed liquid crystal layer; the present scheme innovatively realizes the privacy function in the off state, and only needs to be powered when transparent sharing is needed, thereby greatly reducing the power-on time of the polymer dispersed liquid crystal layer, effectively delaying material aging, and prolonging the overall service life of the film material; at the same time, energy consumption is reduced, meeting the green and energy-saving demand. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art based on the drawings without creative effort shall fall within the scope of the present application.

[0035] Figure 1 Schematic diagram of the polymer dispersed liquid crystal layer provided by the embodiment of the present application Figure 1 ;

[0036] Figure 2 Schematic diagram of the polymer dispersed liquid crystal layer provided by the embodiment of the present application Figure 2 ;

[0037] Figure 3 Schematic diagram of the polymer dispersed liquid crystal layer provided by the embodiment of the present application Figure 3 ;

[0038] Figure 4 Schematic diagram of the preparation device of the integrated power-off privacy PDLC dimming film provided by the embodiment of the present application

[0039] Figure 5 The enlarged view of three cases of the coating wheel A area provided by the embodiment of the present application.

[0040] The following is a supplementary description of the drawings:

[0041] 1-polymer dispersed liquid crystal layer; 11-protrusion; 12-groove;

[0042] 2-preparation device of the integrated power-off privacy PDLC dimming film; 21-ITO unwinding wheel; 22-liquid crystal tank; 23-blade; 24-coating wheel; 25-matching wheel; 26-UV lamp; 27-pressing wheel; 28-drying section; 29-cooling section; 30-winding mechanism. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort shall fall within the scope of the present application.

[0044] The term "one embodiment" or "an embodiment" as may appear in the specification is intended to mean a particular feature, structure, or characteristic described herein. When the specification states a component, feature, structure, or characteristic "may" be included, that particular feature, structure, or characteristic is optionally included. When the specification states a component, feature, structure, or characteristic "may not" be included, that particular feature, structure, or characteristic is optionally excluded. The appearances of the term "may" in various places in the specification are not necessarily all referring to the same feature, structure, or characteristic. As used herein, the term "or" as used herein, without further qualification, can be used to describe either a selective alternative (i.e., "either or but not both") or a non-exclusive alternative (i.e., "one or more " but not all of the components, features, structures, or characteristics described can be included. Similarily, the terms "comprises", "comprising", "includes", "including" and the like can be used in a manner set forth above, but also can be used in a manner otherwise consistent with the context of the particular usage. The term "another" is used herein to describe a particular feature, structure, or characteristic in the context for fresh description. The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the application to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. For example, the described embodiments can be modified to incorporate any of the features described in the above embodiments. It is intended that the application(s) cover all such modifications and variations as fall within the scope of the disclosed application(s). Further, it is intended that the scope of the application(s) disclosed herein include such modifications and variations as fall within the scope of the appended claims.

[0045] When a range of values is disclosed, unless otherwise stated, the endpoints of the ranges are not included. The scope of a range is disclosed as being from the least value ("under" for an upper limit, or "greater than" for a lower limit) to the greatest value ("greater than or equal to" for an upper limit, or "less than or equal to" for a lower limit) of the range. It is specifically contemplated that any and every sub-range between the upper and lower limits of a disclosed range can be disclosed or can be equivalent to one or more explicitly stated or otherwise contemplated sub-ranges. For example, a range of "1 to 10" can include any and all sub-ranges between (and including) the minimum value of 1 and the maximum limit of 10, that is, all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, as well as all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, as well as all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less. In this disclosure, the use of "or" means "and / or" unless stated otherwise. It is further understood that all value ranges are open-ended, and thus constitute both Ranges "up to" a stated value, and "from" a stated value. For example, a range of "1-10" implies that the Ranges "up to 1" and "from 1" are also contemplated.

[0046] Referring now to the drawings Figures 1 to 3 The embodiment of the present application provides a one-piece power-off privacy PDLC dimming film, comprising:

[0047] A first transparent conductive layer;

[0048] A second transparent conductive layer;

[0049] A polymer dispersed liquid crystal layer 1 is arranged between the first transparent conductive layer and the second transparent conductive layer; a microstructure is arranged on a visible side surface of the polymer dispersed liquid crystal layer 1, the microstructure comprises protrusions 11 and grooves 12, the height of the protrusions 11 is 3-7 μm, the width of the grooves 12 is 3-7 μm, and the center line spacing between adjacent two grooves 12 is 8-12 μm; wherein the visible side is a side away from a light source;

[0050] The polymer dispersed liquid crystal layer 1 is in a transparent state in an energized state and in a privacy state in a non-energized state.

[0051] Specifically, the present application aims at the defects of the composite structure of the conventional PDLC privacy film, which is stacked with a privacy film on the lower side of the PDLC film. The differences in the expansion coefficients of the privacy film and the PDLC film cause delamination or uneven light scattering in a high-temperature environment, the refractive loss between layers caused by the multi-layer material stacking reduces the privacy efficiency, the adhesion process of the additional privacy film layer complicates the process and the defects at the interfaces of the multiple layers affect the display and privacy effects, and the PDLC needs to be energized for a long time to achieve privacy, which affects the service life. The present application proposes a microstructure with a height of 3-7 μm and a width of 3-7 μm and a groove with a width of 3-7 μm and a pitch of 8-12 μm on the visible side surface of the PDLC polymer dispersed liquid crystal layer 1 by a direct rolling process. This scheme has no multi-layer composite structure and does not require adhesion and other processes, and the process is simple. The privacy and PDLC dimming functions are realized simultaneously by the same layer, avoiding the problems of delamination or uneven light scattering caused by the differences in the expansion coefficients in a high-temperature environment, the refractive loss between layers, and the defects between layers. The one-piece groove 12 design eliminates the delamination risk to enhance the durability and adapt to large-area continuous production. The working mode is that the PDLC layer is in a transparent state to realize a sharing state when energized and in a fog state to realize a privacy state when de-energized, which is more suitable for high-frequency privacy requirements, avoids the influence of long-time energization of the PDLC layer on the service life, and has no material temperature resistance difference problem caused by the multi-layer structure, and the high-temperature resistance is improved. Only the light in the vertical direction is allowed to pass through in the de-energized state (the side visibility is <30°), and the privacy is more accurate. The groove 12 (width: 3-7 μm) and the protrusion 11 (height: 3-7 μm, pitch between the centers of adjacent grooves 12: 8-12 μm) cooperate with each other through a specific parameter, utilize the haze characteristics of the PDLC layer when de-energized, and ensure the light in the vertical and near-vertical directions to pass through (no grating film is needed to form a PDLC area with an approximate grating), and the light in the non-vertical direction is blocked due to the increase in the relative thickness of the light passing through the PDLC and the reflection and refraction of the groove 12 and the protrusion 11, thereby reducing the thickness of the privacy and dimming layer and reducing the cost. The haze of the PDLC layer in the energized state of the approximate grating structure can be controlled to be <5% (close to the level of the improved PDLC), and the haze in the de-energized state remains >90% to achieve a privacy shielding effect. In addition, the cooperation of the groove 12 and the protrusion 11 also reduces the thickness of the film layer and provides stress buffering, reduces the overall thickness, and improves the flexibility.

[0052] In some specific embodiments, the groove 12 of the microstructure is selected from one of an elongated shape, a triangular shape, or a semicircular shape; and the protrusion 11 is formed between adjacent grooves 12. Specifically, please refer to Figures 1 to 3, the eye marked as "clear" on the top represents that the person can clearly see the screen content at a proper observation distance, and the user can normally and clearly read the information; the eye marked as "privacy" on the right represents that when the person's eye is at the side (non-authorized and non-intended observation position), the screen content cannot be clearly seen, and the arrow on the bottom shows the light source, after the light emitted by the light source passes through the polymer dispersed liquid crystal layer 1, only in the front proper area, the visual effect for clear observation is formed, and on the side, it is difficult to obtain effective visual information. The triangular shape is preferably suitable for small size display screens of 5-12 inches, because the triangular protrusion 11 can make the light rays produce stronger refraction and convergence at the top corner, forming a local high light spot, and the light concentration effect can enhance the light energy concentration in a small area, and in the privacy application, by concentrating high light energy in the normal viewing angle direction, the light transmission efficiency in the vertical and near vertical directions is effectively improved, and the non-vertical direction is relatively weakened due to the convergence of light rays to the top corner area, thereby strengthening the privacy effect without relying on additional grating films; in addition, the light concentration characteristics of the triangular structure are more prominent under narrow viewing angle, and the regularity difference of the light distribution with the change of angle at wide viewing angle helps to accurately control the light intensity and direction in the visible area, to achieve better visible angle regulation, so that the core display content is clearer and more concentrated on the small size screen; the triangular slope can form a continuous gradient refractive index interface and a light transmission interface, reducing the light scattering loss caused by interface abrupt change, and at the same time, through total reflection effect, the large angle light rays are intercepted, and the privacy efficiency is improved; and the triangular groove 12 produces uniform elastic deformation when pressed, which is beneficial to improve the compression strength and deformation buffering capacity of the film layer; preferably, the top corner range of the triangular protrusion 11 is 30°-50°, which is more beneficial to the strong refraction and convergence of light rays at the top corner, and enhances the light intensity in a small area. The long strip shape is suitable for medium size display screens of 13-29 inches, because the texture direction is parallel to the axial direction, the long strip protrusion 11 can guide the light rays to propagate regularly along the axial direction, forming a relatively linear light path in the length direction, so that the light rays are concentrated in the length direction of the long strip, and the linear light concentration characteristic in the specific linear light source strengthening scene can regularly converge the light rays along the main viewing angle direction of the display area, not only ensuring the light transmission clarity of the normal viewing angle and near normal viewing angle, but also regulating the light distribution in the non-vertical direction through linear light concentration, effectively suppressing the lateral light leakage, thereby optimizing the privacy effect and maintaining good light transmission uniformity.The semi-circular shape is preferably suitable for large-size display screens of 30-120 inches, because the arc surface of the semi-circle makes the light refraction more gentle, and compared with sharp shapes (such as triangles), the semi-circular shape can reduce the scattering loss caused by excessive concentration of light during light collection, achieve light collection while making the light propagation softer, optimize the uniformity of light emitted by the large-scale film layer, avoid local over-brightness or over-darkness, and improve the overall display quality; by combining PDLC film haze control (such as haze area and white strip liquid crystal thickness difference), the semi-circular microstructure can adjust the scattering path of light in the film layer, on the basis of effectively diffusing light by using haze, it can assist in precise light collection, which not only ensures the necessary light diffusion and shielding effect, but also maintains the light transmission efficiency of the core area; in addition, the semi-circular structure has no sharp corners, and the deformation rate of the groove 12 is low after on-off power cycling, the privacy performance attenuation is reduced, and the problem of micro-cracks easily generated at the vertex of the triangular groove 12 or the corner of the strip-shaped groove 12 due to electric field stress is avoided, which is especially suitable for the stability requirements of large-size display screens for long-term use; at the same time, the arc-shaped processing is easy to form, has good shaping properties, and has a high yield, which is more conducive to large-scale production in high-difficulty scenes such as large-size display screens.

[0053] In some specific embodiments, when applied to a 5-12 inch display screen, the shape of the groove 12 is triangular;

[0054] When applied to a 13-29 inch display screen, the shape of the groove 12 is strip-shaped;

[0055] When applied to a 30-120 inch display screen, the shape of the groove 12 is semi-circular.

[0056] Specifically, the structure adopts differentiated groove design according to the size difference of the display screen to realize precise optical regulation and mode optimization. For a 5-12 inch small-size display screen, the groove 12 is designed as a triangle, which utilizes the spotlighting characteristics of the triangular point light source to realize fine light control, is more suitable for small-size display requirements, reverses the conventional non-transparent sharing mode to a transparent mode, and changes the anti-peep mode relying on structure regulation to a mode based on physical structure, thereby realizing optimized matching of display functions and application scenarios; for a 13-29 inch medium-size display screen, the groove 12 adopts a long strip design to adapt to the requirements of medium-size display for larger light regulation range and higher uniformity. Compared with the point spotlighting method of small size, the long strip groove can realize more efficient line spotlighting effect, and through the linear light control structure extending along the display area, the continuity and uniformity of optical modulation on the medium-size screen are effectively improved, thereby enhancing the visual consistency and practicality of the anti-peep and transparent mode switching; and in the application of a 30-120 inch large-size display screen, the groove 12 adopts a semicircular design to meet the stringent requirements of super-large display area for wide-area and uniform light regulation. Since point spotlighting and line spotlighting are difficult to realize comprehensive and uniform light control effect in large-size scenarios, a semicircular coating structure is adopted to realize face spotlighting effect, which forms a continuous face-shaped optical modulation unit in the display area, expands the spotlighting coverage range and optimizes the light field distribution uniformity, thereby ensuring that the large-size display screen realizes smooth and consistent switching effect and excellent overall visual experience between the anti-peep mode and the transparent mode.

[0057] In some specific embodiments, when the groove 12 is a semicircular arc surface, the bottom height of the groove 12 is 0.5-1 μm; the bottom height of the groove 12 is the difference between the depth of the groove 12 and the total height of the protrusion 11. While ensuring the stability of the structure, the scattering and shielding of light during propagation are effectively reduced, thereby optimizing the light transmittance and improving the overall light transmission performance.

[0058] In some specific embodiments, the top angle of the triangular groove 12 ranges from 30° to 50°, which can effectively cause strong refraction and convergence effect of light at the top angle, thereby forming a high light concentration point in the local area, enhancing the light concentration intensity in a small range, and further improving the regulation efficiency of the anti-peep function on the light in the vertical and near-vertical directions.

[0059] In some specific embodiments, the grooves 12 and protrusions 11 of the polymer dispersed liquid crystal layer 1 allow only light in the vertical direction to pass through in the off state, and the side viewable range is less than 30°. By the high haze characteristics of the PDLC film in the off state, combined with the microstructure of the grooves 12 and protrusions 11, the light in the vertical and near vertical directions can pass through the grooves 12 smoothly due to the reduced thickness, while the light in the side non-vertical direction is effectively blocked by the increased thickness and multiple reflections and refractions at the interfaces of the grooves 12 and protrusions 11, thereby limiting the viewing angle and strictly controlling the side viewable range to a narrow area of less than 30°, achieving a high-efficiency privacy function without relying on additional grating film layers in the traditional composite structure. The viewing angle control is achieved through the deformation of the microstructure of the single polymer dispersed liquid crystal layer 1, ensuring clear display in the normal viewing angle while effectively preventing the screen information from being viewed from the side.

[0060] The application also provides a preparation method of an integrated off-state privacy PDLC dimming film, including the following steps:

[0061] Preparation of the transparent conductive layer: the first transparent conductive layer and the second transparent conductive layer are continuously fed by the unwinding wheels respectively;

[0062] Coating of the polymer dispersed liquid crystal layer 1: the polymer dispersed liquid crystal material is placed in the liquid crystal tank 22, and the polymer dispersed liquid crystal material is directionally coated by the coating wheel 24 with a regular arrangement structure on the surface; wherein the microstructure of the visible side surface of the coated polymer dispersed liquid crystal layer 1 includes protrusions 11 and grooves 12, the height of the protrusions 11 is 3-7 μm, the width of the grooves 12 is 3-7 μm, and the center line distance between adjacent two grooves 12 is 8-12 μm;

[0063] Coating control: the coated polymer dispersed liquid crystal material is scraped and leveled by the doctor blade 23, so that the polymer dispersed liquid crystal material is uniformly coated and transferred to the surface of the first transparent conductive layer and has a microstructure;

[0064] Preliminary solidification: the first transparent conductive layer coated with the polymer dispersed liquid crystal material is pre-solidified by the ultraviolet curing lamp;

[0065] Laminating treatment: the second transparent conductive layer is aligned and laminated with the first transparent conductive layer by the cooperating wheel 25, and is pressed by the pressing wheel 27, so that the polymer dispersed liquid crystal layer 1 is preliminarily anchored between the first transparent conductive layer and the second transparent conductive layer;

[0066] Baking and solidification: the laminated first transparent conductive layer and second transparent conductive layer are baked;

[0067] Cooling treatment: the baked first transparent conductive layer and second transparent conductive layer are subjected to the cooling treatment of the cooling section 29;

[0068] Roll forming: winding is completed by winding wheel, and an integrated power-off privacy PDLC dimming film is prepared. The polymer dispersed liquid crystal layer 1 of the dimming film has regular arranged protrusions 11 and grooves 12 on the visible side formed by the coating wheel 24.

[0069] Specifically, referring to Figure 3 and Figure 4 , the preparation device 2 of the integrated power-off privacy PDLC dimming film mainly comprises an ITO unwinding wheel 21, a liquid crystal tank 22, a scraper 23, a coating wheel 24, a matching wheel 25, a UV lamp 26, a pressing wheel 27, a drying section 28, a cooling section 29 and a winding mechanism 30, wherein the coating wheel 24 is a core component, and the wheel surface is uniformly distributed with regular arranged structures (the microstructure protrusions 11 on the visible side surface of the polymer dispersed liquid crystal layer 1 after coating have a height of 3-7 μm, the grooves 12 have a width of 3-7 μm, and the center line spacing between adjacent grooves 12 is 8-12 μm). Understandably, the specific size of the microstructure uniformly distributed on the wheel surface can be set according to the related size of the microstructure on the visible side surface of the polymer dispersed liquid crystal layer 1, which is not limited here. It can be designed according to the size of the display screen and the demand for light concentration; the ITO unwinding wheel 21 transports the first and second transparent conductive layers, the liquid crystal tank 22 provides the polymer dispersed liquid crystal material, the coating wheel 24 directionally coats the material and forms a specific microstructure, the matching wheel 25 assists in transmission and matching, the UV lamp 26 cures the material, the pressing wheel 27 presses to anchor the polymer dispersed liquid crystal layer 1 between the two transparent conductive layers, the drying section 28 dries, the cooling section 29 cools, and finally the winding mechanism 30 winds into a film. The preparation process includes the following steps: transparent conductive layer preparation, polymer dispersed liquid crystal layer 1 coating, coating control, preliminary curing, lamination treatment, baking curing, cooling treatment, roll forming, etc.; wherein the coating wheel 24 needs to be precisely processed to keep the microstructure regular, the stainless steel material and smooth surface reduce the deformation and wear of the microstructure, the scraper parameters in the coating and previous links affect the integrity of the microstructure transfer, the energy irradiation time of the UV lamp 26 determines the preliminary shaping effect of the microstructure, the parameters of the pressing wheel 27 ensure the close and stable lamination, the baking section needs to accurately control the temperature, time and uniformity to stabilize the shape of the microstructure and the light concentration structure, and the whole process accurately controls the rotation speed of the coating wheel 24, the substrate conveying speed and the PDLC material supply amount to ensure the uniformity of the film layer and the consistency of the light concentration structure. Compared with the existing ordinary smooth coating wheel process, the technology uses the specific protrusion 11 microstructure formed by the coating wheel 24 to change the light propagation path, refract and reflect the converging light, improve the light concentration efficiency, and can meet the requirements of high-end display equipment, precise lighting and other scenes with high requirements for light intensity and concentration.

[0070] In some specific embodiments, the doctor blade has a doctoring pressure of 0.1-0.5 MPa and a doctoring angle of 0-80° when doctoring, and the tangent of the roller is aligned with the doctoring direction at 0°, which can effectively control the uniformity of coating and the precision of microstructure transfer, so that the polymer dispersed liquid crystal material uniformly covers the first transparent conductive layer and accurately replicates the regularly arranged structure on the coating wheel, while ensuring the integrity of the coating and improving the optical control performance.

[0071] In some specific embodiments, the pressing wheel has a pressing pressure of 0.1-0.7 MPa and a pressing speed of 1-10 m / min when pressing. The interlayer adhesion pressure and speed can be effectively controlled to ensure that the first transparent conductive layer, the polymer dispersed liquid crystal layer and the second transparent conductive layer are tightly anchored, and bubbles, delamination or misplacement are avoided, while preventing damage to the microstructure due to excessive pressure. Reasonable speed ensures uniform transmission of pressing force, improves interlayer bonding strength and structural consistency, thereby enhancing the power-off privacy effect, transparent mode clarity and long-term use stability of the light control film.

[0072] In some specific embodiments, the ultraviolet curing lamp has a radiation energy of 5-100 mW / cm 2 and an irradiation time of 3-20 s. The polymer dispersed liquid crystal material coated on the surface of the first transparent conductive layer forms a preliminary cross-linking structure in a short time, enhances the adhesion and shape stability of the material, prevents flow casting or displacement during subsequent lamination, and avoids excessive curing of the material due to excessive energy or long irradiation time, which affects the interlayer bonding.

[0073] When baking and curing, the baking temperature is 50-150 ℃ and the baking time is 5-60 min, which ensures that the polymer dispersed liquid crystal layer is fully cross-linked and cured under the action of heat to form a stable optical functional layer.

[0074] The examples of the present application are described in detail below, which are exemplary and only used to explain the present application, and cannot be understood as a limitation of the present application.

[0075] An integrated power-off privacy PDLC light control film has the following structure:

[0076] First transparent conductive layer: ITO (indium tin oxide) transparent conductive film is used;

[0077] Second transparent conductive layer: ITO transparent conductive film is also used;

[0078] Polymer dispersed liquid crystal layer: It is sandwiched between the first transparent conductive layer and the second transparent conductive layer, and the surface of the visible side (the side away from the light source) is provided with regularly arranged microstructures, and the specific parameters are as follows:

[0079] Microstructure composition: including protrusions and grooves, wherein the height of the protrusions is 5 μm, the width of the grooves is about 4.14 μm, and the center line distance between two adjacent grooves is 10 μm.

[0080] Microstructure shape: the grooves are triangular, and the top angle of the triangular grooves is 45°.

[0081] An integrated power-off privacy (PDLC) light control film preparation method (for example, 5-12 inch adaptive film, triangular groove): the first transparent conductive layer and the second transparent conductive layer are continuously conveyed by the unwinding wheels respectively, and the tension control is 100 N; the PDLC material (containing nematic liquid crystal and ultraviolet light curing polymer monomer, mass ratio 7:3) is placed in a liquid crystal tank, and the PDLC material is oriented coated by the coating wheel provided with regular triangular microstructures (top angle 45°, not shown in the figure) on the surface; the protrusion height of the microstructure during coating is 5 μm, and the groove width is about 4.14 μm; the PDLC material after coating is scraped by a scraper (pressure 0.15 MPa, angle 45°) to remove excess material and ensure that the microstructure is completely transferred to the surface of the first conductive layer; the first transparent conductive layer coated with the PDLC material is pre-cured by a UV curing lamp (energy 50 mW / cm 2 , irradiation time 3 s) to preliminarily fix the material; the second transparent conductive layer is aligned and attached to the first transparent conductive layer by the matching wheel, and is pressed by the pressing wheel (pressure 0.2 MPa, rotation speed 1 m / min) to anchor the PDLC layer between the two conductive layers; the attached film layer is placed in an oven and baked at 80℃ for 10 min to completely cure the polymer monomer; naturally cooled to room temperature (25℃); the winding is completed by the winding wheel to obtain the final light control film, and the PDLC layer on the visible side has regular triangular microstructures.

[0082] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for preparing an integrated power-off privacy-protecting PDLC dimming film, characterized in that, Includes the following steps: Preparation of transparent conductive layer: The first transparent conductive layer and the second transparent conductive layer are continuously fed by the unwinding reel; Polymer dispersed liquid crystal layer coating: The polymer dispersed liquid crystal material is placed in a liquid crystal tank (22), and the polymer dispersed liquid crystal material is coated in an orientation manner by a coating wheel (24) with a regular arrangement structure on its surface; Coating control: The polymer-dispersed liquid crystal material is coated and leveled using a scraper, so that the polymer-dispersed liquid crystal material is uniformly coated and transferred to the surface of the first transparent conductive layer and has a microstructure; Preliminary curing: The first transparent conductive layer coated with the polymer-dispersed liquid crystal material is pre-cured using an ultraviolet curing lamp; Bonding process: The second transparent conductive layer is aligned and bonded to the first transparent conductive layer using mating rollers, and then pressed together using pressing rollers, so that the polymer-dispersed liquid crystal layer is initially anchored between the first transparent conductive layer and the second transparent conductive layer; Baking and curing: The first transparent conductive layer and the second transparent conductive layer after being bonded together are baked. Cooling treatment: The first transparent conductive layer and the second transparent conductive layer are subjected to a cooling treatment after baking; Winding and forming: Winding is completed by winding wheel to obtain an integrated power-off privacy PDLC dimming film. The visible side of the polymer dispersed liquid crystal layer of the dimming film has regularly arranged protrusions and grooves formed by the microstructure of the coating wheel (24).

2. The method for preparing an integrated power-off privacy PDLC dimming film according to claim 1, characterized in that, The scraping pressure of the scraper during scraping is 0.1~0.5 MPa, and the scraping angle is 0°~80°.

3. The method for preparing an integrated power-off privacy PDLC dimming film according to claim 1, characterized in that, The pressing roller applies a pressing pressure of 0.1~0.7 MPa and a pressing speed of 1~10 m / min.

4. The method for preparing an integrated power-off privacy PDLC dimming film according to claim 1, characterized in that, The radiant energy during curing by the ultraviolet curing lamp is 5~100 mW / cm². 2 The irradiation time is 3~20 s; During the baking and curing process, the baking temperature is 50~150 ℃ and the baking time is 5~60 min.

5. An integrated power-off privacy PDLC dimming film prepared by the preparation method according to any one of claims 1 to 4, characterized in that, include: First transparent conductive layer; Second transparent conductive layer; A polymer-dispersed liquid crystal layer is sandwiched between a first transparent conductive layer and a second transparent conductive layer; the visible side surface of the polymer-dispersed liquid crystal layer is provided with microstructures, the microstructures including protrusions and grooves, the height of the protrusions is 3~7μm, the width of the grooves is 3~7μm, and the center-line distance between two adjacent grooves is 8~12μm; wherein, the visible side is the side facing away from the light source; The polymer-dispersed liquid crystal layer is transparent when energized and privacy-protected when de-energized.

6. The integrated power-off privacy PDLC dimming film according to claim 5, characterized in that, The groove shape of the microstructure is selected from one of the following: elongated, triangular, or semi-circular; wherein a protrusion is formed between adjacent grooves.

7. The integrated power-off privacy PDLC dimming film according to claim 5, characterized in that, When applied to 5-12 inch displays, the groove is triangular in shape; When applied to 13-29 inch displays, the groove is elongated. When applied to 30-120 inch displays, the groove is semi-circular in shape.

8. The integrated power-off privacy PDLC dimming film according to claim 5, characterized in that, When the groove is a semi-circular arc surface, the bottom height of the groove is 0.5~1μm; the bottom height of the groove is the difference between the depth of the groove and the total height of the protrusion.

9. The integrated power-off privacy PDLC dimming film according to claim 7, characterized in that, The apex angle of the triangular groove ranges from 30° to 50°.

10. The integrated power-off privacy PDLC dimming film according to claim 5, characterized in that, The grooves and protrusions of the polymer-dispersed liquid crystal layer allow only vertical light to pass through when the power is off, and the side viewing angle is less than 30°.

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