PDLC dimming film

Abstract

The present application relates to a PDLC dimming film, consisting of a first transparent conductive substrate, a second transparent conductive substrate, and a dimming layer sandwiched between the first transparent conductive substrate and the second transparent conductive substrate. The dimming layer comprises at least two polymer-dispersed dye liquid crystal layers and a transparent conductive spacer layer disposed between the polymer-dispersed dye liquid crystal layers; the transparent conductive spacer layer consists of a first conductive layer, a second conductive layer, and a transparent base material layer sandwiched between the first conductive layer and the second conductive layer; and the sides of the first conductive layer and the second conductive layer facing away from the transparent base material layer respectively fit the polymer-dispersed dye liquid crystal layers. The present technical solution solves the problems in existing PDLC dimming films such as a low contrast ratio of visible light transmittance and off-state light leakage.

Description

A PDLC dimming film Technical Field

[0001] The present application relates to the field of dimming films, and in particular to a PDLC dimming film. Background Art

[0002] PDLC dimming films are widely used in architectural and transportation glass. Without an applied electric field, the film exhibits strong light scattering and is opaque due to the significant difference in refractive index between the liquid crystal droplets and the polymer. When an electric field is applied, the director of the liquid crystal droplets aligns with the electric field, matching the long-axis refractive index of the liquid crystal and the polymer. The film becomes transparent and can be switched between transparent and opaque by powering it on and off, providing privacy protection and serving as a projection screen.

[0003] Existing PDLC dimming films have a low contrast ratio (the ratio of visible light transmittance in the on-state to that in the off-state) under operating voltage (less than 5), which is mainly manifested by a high visible light transmittance in the off-state (generally greater than 60%). When low transmittance and high contrast are required, the light-shielding performance of existing PDLC dimming films cannot meet the requirements. In addition, the use of transparent microbeads as spacers in the polymer dispersed liquid crystal layer causes light leakage in the PDLC dimming film in the off-state. Therefore, there is a need for a PDLC dimming film with high contrast that can achieve a dimming effect with high light-shielding performance in the off-state and high transmittance in the on-state.

[0004] Summary of the Invention

[0005] PDLC: Polymer dispersed liquid crystal, is a liquid crystal dispersed in an organic solid polymer matrix in the form of micron-sized droplets. Since the optical axes of the droplets composed of liquid crystal molecules are in free orientation, their refractive index does not match that of the matrix. When light passes through the matrix, it is strongly scattered by the droplets and appears opaque, milky white or translucent.

[0006] In order to solve the problem that the current PDLC dimming film has a low transmittance contrast in the on-state and poor light-shielding performance in the off-state, the present application provides a PDLC dimming film.

[0007] In a first aspect, the present application provides a PDLC dimming film, which adopts the following technical solution:

[0008] A PDLC dimming film comprises a first transparent conductive substrate, a second transparent conductive substrate, and a dimming layer sandwiched therebetween. The dimming layer comprises at least two polymer disperse dye liquid crystal layers and a transparent conductive spacer layer disposed between the polymer disperse dye liquid crystal layers. The transparent conductive spacer layer comprises a first conductive layer, a second conductive layer, and a transparent substrate layer sandwiched between the first and second conductive layers. The first and second conductive layers are respectively bonded to the polymer disperse dye liquid crystal layers on their sides facing away from the transparent substrate layer.

[0009] Typically, but not limiting, the first and second conductive layers are single-layer or multi-layer structures, and are selected from one or more transparent conductive oxides such as nanosilver conductive layers, nano-zinc aluminum oxide (AZO), indium tin oxide (ITO), zinc oxide (ZnO), aluminum gallium indium tin oxide (AlGaInSnO), aluminum zinc oxide (AZO), tin oxide (SnO2), indium oxide (In2O3), and zinc tin oxide (SnZnO). The transparent substrate layer is a transparent single-layer or multi-layer structure, and is selected from one or more transparent conductive oxides such as PET layers and PC layers.

[0010] By adopting the above technical solution,

[0011] Preferably, the on-off contrast ratio is greater than or equal to 10.

[0012] Preferably, the visible light transmittance in the on state is not greater than 80%.

[0013] Preferably, the at least two polymer disperse dye liquid crystal layers are electrically connected in series or in parallel.

[0014] Preferably, the first transparent conductive substrate and the second transparent conductive substrate are a double-layer structure, the first transparent conductive substrate is composed of a first transparent substrate and a first transparent conductive layer, the second transparent conductive substrate is composed of a second transparent substrate and a second transparent conductive layer, and the first transparent conductive layer and the second transparent conductive layer are both bonded to the polymer dispersed liquid crystal layer.

[0015] Preferably, the polymer disperse dye liquid crystal layer includes anthraquinone dichroic dyes, and the anthraquinone dichroic dyes are two or more of the compounds represented by the following formulas (I-1) to (I-8);

[0016]

[0017]

[0018] wherein A1, A2, A3, A4, A5, A6, A7, A8 and A9 are each independently selected from -H, -O-, -S-, -NH-, -COO-, -OCO-, -O(CH2CH2O)-, -CH2O-, -CH=CH-, -CF=CF-, -CF2-CF2- or -(CH2)n-, where n is an integer from 1 to 20; wherein H1, H2, H3, H4, H5, H6 , H7, H8, H9, H10, H11, H12, H13, H14, H15, H16 and H17 are each independently selected from the following structures: -H, cyclohexyl, cyclohexenyl, cyclohexadienyl, aryl, naphthyl, cyclopentanyl, cyclopentenyl, cyclobutanyl, optionally substituted heteroaryl, wherein the heteroaryl is selected from benzothiazolyl, benzoxazinyl, quinazolinyl, quinolinyl, isoquinolinyl, quinoxalinyl, pyridyl, pyrrolyl, Oxazolyl, indolyl, pyridazinyl, pyrimidinyl, pyrazinyl, 2-cyanopyridin-5-yl, furyl, dibenzofuran-4-yl, benzofuranyl, dihydrothienodioxin, benzothienyl and dibenzothienyl; R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 are each independently selected from: -H, C1 to C20 -C1-C20 chain alkyl, C1-C20 chain alkyl halide, C1-C20 chain alkyl cyanide, -OCH3, -CF3, -OCF3, -C(CH3)3, -CN, -F, -Cl or -NCS; and can also be selected from: a structure in which one or more non-adjacent -CH2- in the C1-C20 chain alkyl are independently replaced by -O-, -COO, -OCO-, -C=C-, CF=CF- or -C≡C-.

[0019] Preferably, the polymer disperse dye liquid crystal layer comprises 1-10 wt % of anthraquinone dichroic dye in terms of weight percentage.

[0020] Preferably, the polymer disperse dye liquid crystal layer further comprises the following components in weight percentage: 40-65 wt% of liquid crystal composition; 5-40 wt% of prepolymer; 5-30 wt% of active diluent; 0.02-5 wt% of photoinitiator; 0-15 wt% of chiral agent; and 0.1-0.9 wt% of spacer.

[0021] Preferably, the liquid crystal composition has a dielectric constant Δε (1 KHZ 25° C.) of 8 to 20, a clearing point > 90° C., a melting point < -30° C., an optical anisotropy of 0.18 to 0.28, and a rotational viscosity at 20° C. < 120 cP.

[0022] Typically, but not limiting, the prepolymer is one or more of polyurethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, and polybutadiene acrylate. The reactive diluent is one or more of hydroxyethyl methacrylate, 1,4-butanediol diacrylate, 4-hydroxybutyl acrylate, 2-hydroxypropyl methacrylate, ethyl methacrylate, n-octyl methacrylate, trimethylolpropane triacrylate, isobornyl acrylate, isobornyl methacrylate, hydroxypropyl acrylate, and 2-carboxyethyl acrylate. The photoinitiator is a mixture of two or more of 1-hydroxycyclohexylphenyl ketone, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, α,α-dimethoxy-α-phenylacetophenone, and 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone. The particle size of the spacer particles is 8 to 30 μm. The chiral agent is one or more of the compounds represented by the following formulas (П-1) to (П-7);

[0023] Preferably, the PDLC dimming film with high contrast has a contrast ratio CR greater than or equal to 10 in both the energized and de-energized states.

[0024] Preferably, during the preparation of the dye PDLC dimming film, the PDLC dimming film is cured by ultraviolet light, and the required energy is 3 to 30 mw / cm 2 , curing for 2 to 10 minutes.

[0025] In summary, this application includes at least one of the following beneficial technical effects:

[0026] 1. By using at least two polymer disperse dye liquid crystal layers and separating them with a transparent conductive substrate layer having two conductive layers, the number of adhesive film layers and substrate layers required for direct bonding of a single-layer dimming film is reduced, the structure of the dimming film is simplified, and the problems of off-state light leakage and viewing angle dependence of light-shielding performance are solved, thereby increasing the contrast adjustment range of the dimming film.

[0027] 2. The dimming layer contains dichroic dyes, which can adjust the visible light transmittance of the dimming film under different switching conditions and further increase the switching contrast CR;

[0028] 3. The light leakage phenomenon caused by the gaps between the transparent microbeads in the single-layer polymer dispersed liquid crystal layer can be blocked by the two overlapping polymer dispersed liquid crystal layers in the dimming film, solving the problem of light leakage in the off state of the single-layer PDLC dimming film. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic structural diagram of a PDLC dimming film according to Example 1. FIG.

[0030] FIG2 is a schematic structural diagram of a PDLC dimming film according to Example 4.

[0031] Explanation of the accompanying reference numerals: 10, first transparent conductive substrate; 11, first transparent substrate; 12, first transparent conductive layer; 20, second transparent conductive substrate; 21, second transparent substrate; 22, second transparent conductive layer; 30, dimming layer; 301, first polymer dispersed liquid crystal layer; 302, second polymer dispersed liquid crystal layer; 303, third polymer dispersed liquid crystal layer; 310, transparent conductive spacer layer; 311, first conductive layer; 312, second conductive layer; 313, transparent base material layer. DETAILED DESCRIPTION

[0032] The present application is further described in detail below with reference to Figures 1-2.

[0033] In order to enable people in this technical field to better understand the solution of this application, the technical solution in the embodiment of this application will be clearly and completely described below in combination with the drawings in the embodiment of this application. Obviously, the described embodiment is only a part of the embodiment of this application, not all of the embodiments.

[0034] Optical properties: Tested in accordance with the method specified in GB / T5137.2-2002 "Test methods for optical properties of automotive safety glass".

[0035] The term "on state" mentioned in this application document refers to a power-on state; and "off state" refers to a power-off state.

[0036] The term "visible light" mentioned in this application document has a wavelength range of 400-700nm.

[0037] The term "contrast ratio" mentioned in this application document refers to the ratio of the visible light transmittance of the switchable film in the on and off states under the operating voltage. For the convenience of comparison, the operating voltage is set to 60 volts. The specific calculation method is:

[0038] Contrast ratio CR = on-state transmittance / off-state transmittance.

[0039] Unless otherwise specified, the raw materials used in the examples of this application are commercially available.

[0040] In the following examples, the anthraquinone dichroic dyes used are compounds shown in Table 1:

[0041] Table 1: Anthraquinone dichroic dyes

[0042] In the following examples, the names used, such as nematic liquid crystal E7 and C70, are liquid crystal compositions, which are purchased from the market by those skilled in the art.

[0043] In the following examples, the particle size of the spacer particles is 20 μm.

[0044] The embodiments of the present application only list the cases where there are two or three polymer dye dispersed liquid crystal layers. The cases where there are more than three polymer dye dispersed liquid crystal layers can be similarly listed according to this solution.

[0045] The embodiments of the present application disclose a PDLC dimming film.

[0046] Example 1

[0047] Referring to FIG1 , a PDLC dimming film includes a first transparent conductive substrate 10 and a second transparent conductive substrate 20 symmetrically disposed on either side of the dimming film. The first transparent conductive substrate 10 includes a first transparent substrate 11 on the outside and a first transparent conductive layer 12 on the inside. The second transparent conductive substrate 20 includes a second transparent substrate 21 on the outside and a second transparent conductive layer 22 on the inside. A first polymer dispersed dye liquid crystal dimming layer 301 and a second polymer dispersed dye liquid crystal dimming layer 302 are sandwiched between the two transparent conductive substrates. The first polymer dispersed dye liquid crystal dimming layer 301 and the second polymer dispersed dye liquid crystal dimming layer 302 are separated by a transparent conductive spacer layer 310. The transparent conductive spacer layer 310 includes, from top to bottom, a first conductive layer 311, a transparent substrate layer 313, and a second conductive layer 312. The first conductive layer 311 is a first transparent ITO conductive layer, the second conductive layer 312 is a second transparent ITO conductive layer, and the transparent substrate layer 313 is a PET transparent substrate layer.

[0048] In this embodiment, the first transparent substrate 11 is a transparent PET substrate layer; the first transparent conductive layer 12 is a transparent ITO conductive layer; the second transparent substrate 21 is a transparent PET substrate layer; and the second transparent conductive layer 22 is an ITO conductive layer. The two polymer disperse dye liquid crystal dimming layers are electrically connected in parallel.

[0049] The first polymer dispersed dye liquid crystal dimming layer 301 and the second polymer dispersed dye liquid crystal dimming layer 302 use the same composition and ratio, and the components and their corresponding weight percentages are shown in Table 2:

[0050] Table 2: Composition of polymer disperse dye liquid crystal dimming layer

[0051] Among them, the preparation method of the polymer disperse dye liquid crystal dimming layer is as follows: after uniformly mixing the anthraquinone dichroic dye and the liquid crystal composition, a mixture A is obtained; after uniformly mixing the active diluent and the prepolymer, a mixture B is obtained; after uniformly mixing the mixture A and the mixture B, a mixture C is obtained; after adding a photoinitiator, spacer particles and a chiral agent to the mixture C, the mixture is stirred uniformly in the dark at room temperature (25°C) to obtain the polymer disperse dye liquid crystal dimming layer.

[0052] Example 2, a PDLC dimming film. This example differs from Example 1 in that the polymer dispersed liquid crystal layer has a different formulation. The first polymer dispersed dye liquid crystal dimming layer 301 and the second polymer dispersed dye liquid crystal dimming layer 302 use the same composition and ratio. The components and their corresponding weight percentages are shown in Table 3:

[0053] Table 3: Composition of polymer disperse dye liquid crystal dimming layer

[0054] Among them, the preparation method of the polymer disperse dye liquid crystal dimming layer is as follows: after uniformly mixing the anthraquinone dichroic dye and the liquid crystal composition, a mixture A is obtained; after uniformly mixing the active diluent and the prepolymer, a mixture B is obtained; after uniformly mixing the mixture A and the mixture B, a mixture C is obtained; after adding a photoinitiator, spacer particles and a chiral agent to the mixture C, the mixture is stirred uniformly in the dark at room temperature (25°C) to obtain the polymer disperse dye liquid crystal dimming layer.

[0055] Example 3, a PDLC dimming film. This example differs from Example 1 in that the formulation of the polymer dispersed liquid crystal layer is different. The first polymer dispersed dye liquid crystal dimming layer 301 and the second polymer dispersed dye liquid crystal dimming layer 302 use the same composition and ratio. The components and their corresponding weight percentages are shown in Table 4:

[0056] Table 4: Composition of polymer disperse dye liquid crystal dimming layer

[0057] Among them, the preparation method of the polymer disperse dye liquid crystal dimming layer is as follows: after uniformly mixing the anthraquinone dichroic dye and the liquid crystal composition, a mixture A is obtained; after uniformly mixing the active diluent and the prepolymer, a mixture B is obtained; after uniformly mixing the mixture A and the mixture B, a mixture C is obtained; after adding a photoinitiator, spacer particles and a chiral agent to the mixture C, the mixture is stirred uniformly in the dark at room temperature (25°C) to obtain the polymer disperse dye liquid crystal dimming layer.

[0058] Example 4

[0059] 2 , a PDLC dimming film includes:

[0060] The dimming film comprises a two-layer structure, a first transparent conductive substrate 10 and a second transparent conductive substrate 20, symmetrically arranged on both sides. The first transparent conductive substrate 10 has a first transparent substrate 11 on the outside and a first transparent conductive layer 12 on the inside. The second transparent conductive substrate 20 has a second transparent substrate 21 on the outside and a second transparent conductive layer 22 on the inside. A first polymer dispersed dye liquid crystal dimming layer 301, a second polymer dispersed dye liquid crystal dimming layer 302, and a third polymer dispersed dye liquid crystal dimming layer 303 are sandwiched between the two transparent conductive substrates. The first polymer dispersed dye liquid crystal dimming layer 301 and the second polymer dispersed dye liquid crystal dimming layer 302 and the third polymer dispersed dye liquid crystal dimming layer 303 are separated by two transparent conductive spacer layers 310, respectively. The transparent conductive spacer layers 310 include a first conductive layer 311, a transparent base material layer 313, and a second conductive layer 312 arranged from top to bottom. The first conductive layer 311 is a transparent ITO conductive layer, the second conductive layer 312 is a transparent ITO conductive layer, and the transparent substrate layer 313 is a PET transparent substrate layer.

[0061] In this embodiment, the first transparent substrate 11 is a transparent PET substrate layer; the first transparent conductive layer 12 is a transparent ITO conductive layer; the second transparent substrate 21 is a transparent PET substrate layer; and the second transparent conductive layer 22 is an ITO conductive layer. The three polymer disperse dye liquid crystal dimming layers are electrically connected in parallel.

[0062] The first polymer disperse dye liquid crystal dimming layer 301, the second polymer disperse dye liquid crystal dimming layer 302 and the third polymer disperse dye liquid crystal dimming layer 303 all use the same composition and ratio, and the components and their corresponding weight percentages are shown in Table 5:

[0063] Table 5: Composition of polymer disperse dye liquid crystal dimming layer

[0064] Example 5, a PDLC dimming film. This example differs from Example 1 in that it includes three polymer dispersed liquid crystal layers. The compositions and proportions of the first polymer dispersed dye liquid crystal dimming layer 301, the second polymer dispersed dye liquid crystal dimming layer 302, and the third polymer dispersed dye liquid crystal dimming layer 303 are the same. The components and their corresponding weight percentages are shown in Table 6:

[0065] Table 6: Composition of polymer disperse dye liquid crystal dimming layer

[0066] Example 6, a PDLC dimming film. This example differs from Example 3 in that it includes three polymer dispersed liquid crystal layers. The compositions and proportions of the first polymer dispersed dye liquid crystal dimming layer 301, the second polymer dispersed dye liquid crystal dimming layer 302, and the third polymer dispersed dye liquid crystal dimming layer 303 are the same. The components and their corresponding weight percentages are shown in Table 7:

[0067] Table 7: Composition of polymer disperse dye liquid crystal dimming layer

[0068] Example 7, a PDLC dimming film. The difference between this example and Example 1 is that the amount of the anthraquinone dichroic dye is 2%, and the amount of the liquid crystal composition is 35%.

[0069] Example 8, a PDLC dimming film. The difference between this example and Example 1 is that the two polymer disperse dye liquid crystal dimming layers are electrically connected in series, the amount of anthraquinone dichroic dye used is 4%, and the amount of liquid crystal composition used is 33%.

[0070] Comparative Example

[0071] Comparative Example 1, a PDLC dimming film. The difference between this comparative example and Example 2 is that a PDLC dimming film includes a two-layer structure of a first transparent conductive substrate 10 and a second transparent conductive substrate 20 symmetrically arranged on both sides of the dimming film. The outer side of the first transparent conductive substrate 10 is a first transparent substrate 11, and the inner side is a first transparent conductive layer 12. The outer side of the second transparent conductive substrate 20 is a second transparent substrate 21, and the inner side is a second transparent conductive layer 22. A first polymer dispersed liquid crystal dimming layer 301 is sandwiched between the two transparent conductive substrates, which does not contain a dye.

[0072] In this comparative example, the first transparent substrate 11 is a transparent PET substrate layer; the first transparent conductive layer 12 is a transparent ITO conductive layer; the second transparent substrate 21 is a transparent PET substrate layer; and the second transparent conductive layer 22 is an ITO conductive layer.

[0073] In the polymer dispersed liquid crystal dimming layer composition, the anthraquinone dichroic dye is replaced by an equal amount of liquid crystal composition.

[0074] Comparative Example 2, a PDLC dimming film. The difference between this comparative example and Example 2 is that a PDLC dimming film includes a two-layer structure of a first transparent conductive substrate 10 and a second transparent conductive substrate 20 symmetrically arranged on both sides of the dimming film. The outer side of the first transparent conductive substrate 10 is a first transparent substrate 11, and the inner side is a first transparent conductive layer 12. The outer side of the second transparent conductive substrate 20 is a second transparent substrate 21, and the inner side is a second transparent conductive layer 22. A first polymer dispersed liquid crystal dimming layer 301 and a second polymer dispersed liquid crystal dimming layer 302 are sandwiched between the two transparent conductive substrates. Neither the first polymer dispersed liquid crystal dimming layer 301 nor the second polymer dispersed liquid crystal dimming layer 302 contains a dye. The first polymer dispersed liquid crystal dimming layer 301 and the second polymer dispersed liquid crystal dimming layer 302 are separated by a transparent conductive spacer layer 310. The transparent conductive spacer layer 310 includes a first conductive layer 311, a first transparent base material layer 313, and a second conductive layer 312 arranged from top to bottom. The first conductive layer 311 is a first transparent ITO conductive layer, the second conductive layer 312 is a second transparent ITO conductive layer, and the first transparent substrate layer 313 is a PET transparent substrate layer.

[0075] In this embodiment, the first transparent substrate 11 is a transparent PET substrate layer; the first transparent conductive layer 12 is a transparent ITO conductive layer; the second transparent substrate 21 is a transparent PET substrate layer; and the second transparent conductive layer 22 is an ITO conductive layer. The two polymer dispersed liquid crystal dimming layers are electrically connected in parallel.

[0076] In the polymer dispersed liquid crystal dimming layer composition, the anthraquinone dichroic dye is replaced by an equal amount of liquid crystal composition.

[0077] Comparative Example 3, a PDLC dimming film, which differs from Example 2 in that a PDLC dimming film includes a dimming film, a two-layer structure of a first transparent conductive substrate 10 and a second transparent conductive substrate 20 symmetrically arranged on both sides of the dimming film, the outer side of the first transparent conductive substrate 10 is a first transparent substrate 11, and the inner side is a first transparent conductive layer 12, the outer side of the second transparent conductive substrate 20 is a second transparent substrate 21, and the inner side is a second transparent conductive layer 22, and a first polymer disperse dye liquid crystal dimming layer 301 is sandwiched between the two transparent conductive substrates.

[0078] In this comparative example, the first transparent substrate 11 is a transparent PET substrate layer; the first transparent conductive layer 12 is a transparent ITO conductive layer; the second transparent substrate 21 is a transparent PET substrate layer; and the second transparent conductive layer 22 is an ITO conductive layer.

[0079] Comparative Example 4, a PDLC dimming film, differs from Example 2 in that, between the first polymer dispersed dye liquid crystal dimming layer 301 and the second polymer dispersed dye liquid crystal dimming layer 302, there are distributed from top to bottom a first transparent ITO conductive layer, a PET transparent substrate layer, a film layer, a first transparent PET transparent substrate layer, and a second transparent ITO conductive layer.

[0080] Performance testing

[0081] Test 1: The PDLC films prepared in Examples 1-8 and Comparative Examples 1-4 were used as test subjects. The films were cut into 100 mm × 100 mm sheets and subjected to a power-on haze test and a full light transmittance test according to the method specified in GB / T 2410-2008. The power-on voltage was 60 V. The test results are shown in Table 8.

[0082] Experiment 2: The dye-based PDLC material compositions of Examples 1-3 were used as test subjects. The dye-based PDLC material compositions were evenly applied between three transparent substrates with conductive coatings using a coating laminator. The middle transparent substrate with conductive coatings had a double-sided conductive structure. The films were then UV-cured and cut into 100 mm x 100 mm sections to produce PDLC dimming films. The double-sided conductive structure comprised a first conductive layer, a second conductive layer, and a substrate layer sandwiched between the first and second conductive layers. The L*, a*, and b* values ​​of the test samples were recorded in Table 9.

[0083] Table 8: Test results of experiment 1

[0084] Table 9: Test results of Experiment 2

[0085] A comparison of Examples 1-3 and Comparative Examples 1-4, along with Table 8, reveals that the PDLC film prepared in this application utilizes a transparent conductive substrate layer comprising two conductive layers to separate the polymer disperse dye liquid crystal layers. This reduces the number of adhesive film and substrate layers required for direct bonding of a single layer of the film, simplifies the film's structure, and substantially reduces its performance. The use of at least two polymer disperse dye liquid crystal layers addresses the issues of off-state light leakage and viewing angle dependence of light-shielding performance, expands the film's contrast adjustment range, and improves its performance.

[0086] Combining Examples 1-8 and Table 8, it can be seen that when the polymer disperse dye liquid crystal layer in the PDLC dimming film is set to three layers, the PDLC dimming film prepared therefrom not only has a greatly improved contrast adjustment range, but also has a significantly improved light-shielding performance. This is because the three overlapping polymer disperse dye liquid crystal layers further block each other, and three layers can form a nearly 100% shielding. In addition, there is no adhesive film layer between the polymer disperse dye liquid crystal layers of the present application. The more overlapping layers of the polymer disperse dye liquid crystal layers, the more obvious the cost savings and process simplification effects. In addition, when using the PDLC dimming film prepared using the structure of the present application, different dyes can be configured according to specific needs to meet the needs of different dimming films. This has strong flexibility and can produce a variety of products with excellent performance.

[0087] From Examples 1-3 and Table 9, it can be seen that the PDLC dimming film under the structure of the present application has a small color difference variation, which can ensure the color stability of the same batch of products and ensure the stability of product quality while maintaining good product performance.

[0088] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A PDLC dimming film, comprising a first transparent conductive substrate (10), a second transparent conductive substrate (20) and a dimming layer (30) sandwiched therebetween, characterized in that: The dimming layer (30) comprises at least two polymer disperse dye liquid crystal layers and a transparent conductive spacer layer (310) arranged between the polymer disperse dye liquid crystal layers; the transparent conductive spacer layer (310) comprises a first conductive layer (311), a second conductive layer (312), and a transparent substrate layer (313) sandwiched between the first conductive layer (311) and the second conductive layer (312); the first conductive layer (311) and the second conductive layer (312) are respectively bonded to the polymer disperse dye liquid crystal layers on their sides facing away from the transparent substrate layer.

2. The PDLC dimming film according to claim 1, characterized in that: The contrast ratio of the switching state is greater than or equal to 10.

3. The PDLC dimming film according to claim 1, characterized in that: The visible light transmittance in the on state is not greater than 80%.

4. The PDLC dimming film according to claim 1, characterized in that: The at least two polymer disperse dye liquid crystal layers are electrically connected in series or in parallel.

5. The PDLC dimming film according to claim 1, characterized in that: The first transparent conductive substrate (10) and the second transparent conductive substrate (20) are double-layer structures; the first transparent conductive substrate (10) is composed of a first transparent substrate (11) and a first transparent conductive layer (12); the second transparent conductive substrate (20) is composed of a second transparent substrate (21) and a second transparent conductive layer (22); the first transparent conductive layer (11) and the second transparent conductive layer (22) are both bonded to the polymer dispersed liquid crystal layer.

6. A PDLC dimming film according to any one of claims 2 to 5, characterized in that: The polymer disperse dye liquid crystal layer includes anthraquinone dichroic dyes, and the anthraquinone dichroic dyes are two or more of the compounds represented by the following formulas (I-1) to (I-8); wherein A1, A2, A3, A4, A5, A6, A7, A8 and A9 are each independently selected from -H, -O-, -S-, -NH-, -COO-, -OCO-, -O(CH2CH2O)-, -CH2O-, -CH=CH-, -CF=CF-, -CF2-CF2- or -(CH2)n-, where n is an integer from 1 to 20; wherein H1, H2, H3, H4, H5, H6 H7, H8, H9, H10, H11, H12, H13, H14, H15, H16 and H17 are each independently selected from the following structures: -H, cyclohexyl, cyclohexenyl, cyclohexadienyl, aryl, naphthyl, cyclopentanyl, cyclopentenyl, cyclobutanyl, optionally substituted heteroaryl, wherein the heteroaryl is selected from benzothiazolyl, benzoxazinyl, quinazolinyl, quinolyl, isoquinolyl, quinoxalinyl, pyridinyl, pyrrolyl, Oxazolyl, indolyl, pyridazinyl, pyrimidinyl, pyrazinyl, 2-cyanopyridin-5-yl, furanyl, dibenzofuran-4-yl, benzofuranyl, dihydrothienodioxin, benzothienyl and dibenzothienyl; R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 are each independently selected from: -H, C1 to C20 The alkyl group may also be selected from: a C1-C20 alkyl chain, a C1-C20 alkyl halide, a C1-C20 alkyl cyanide, -OCH3, -CF3, -OCF3, -C(CH3)3, -CN, -F, -Cl or -NCS; and may also be selected from: a structure in which one or more non-adjacent -CH2- in the C1-C20 alkyl chain are independently replaced by -O-, -COO, -OCO-, -C=C-, CF=CF- or -C≡C-.

7. The PDLC dimming film according to claim 6, characterized in that: The polymer disperse dye liquid crystal layer includes 1-10 wt % of anthraquinone dichroic dye in terms of weight percentage.

8. The PDLC dimming film according to claim 7, characterized in that: The polymer disperse dye liquid crystal layer further comprises the following components, calculated by weight percentage: 40-65wt% of liquid crystal composition; 5-40wt% of prepolymer; 5-30wt% of active diluent; 0.02-5wt% of photoinitiator; 0-15wt% of chiral agent; and 0.1-0.9wt% of spacer.

9. A PDLC dimming glass with high contrast, characterized in that: The PDLC dimming film comprises the PDLC dimming film according to any one of claims 1 to 5, wherein a glue film layer and a glass layer are sequentially arranged on two sides of the dimming film.

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