A dye PDLC dimming film and its application

Abstract

This invention relates to the field of dimming film technology, specifically disclosing a dye-modified PDLC dimming film and its applications. The dye-modified PDLC dimming film provided by this invention comprises two layers of transparent ITO conductive films and a dye-modified PDLC composition sandwiched in between; wherein the transparent ITO conductive films have a transmittance of 10.00%~70.00%, an a value of -5~5, and a b value of -4~8; the dye-modified PDLC dimming film has a contrast ratio ≥20, a dark-state transmittance of 0.00%~1.00%, and a bright-state transmittance of 2.00%~20.00%. This invention optimizes the film material of the dye-modified PDLC dimming film, resulting in a dye-modified PDLC dimming film with excellent contrast ratio, dark-state transmittance, and bright-state transmittance, significantly solving the problem of low contrast and large color difference in existing dye-modified PDLC dimming films after prolonged exposure to sunlight.

Description

Technical Field

[0001] This invention relates to the field of dimming films, and specifically to a dye PDLC dimming film and its applications. Background Technology

[0002] Polymer-dispersed liquid crystal films (PDLC films) appear milky white when not energized, turning transparent when energized. Because they can rapidly switch states at relatively low voltages, they are widely used in smart glass, automotive sunroofs, and other applications. Recently, adding various dichroic dyes to PDLCs has been observed to alter their appearance and improve control over light transmittance, thereby enhancing contrast.

[0003] Dichroic dyes exhibit different colors due to the different light absorption along the long and short axes of their molecules. By mixing dye molecules of different colors to form a gray-black color and adding it to a polymer-dispersed liquid crystal, dye-modified liquid crystal (PDLC) can be produced. Without an applied electric field, the random arrangement of the liquid crystal causes strong scattering, and the dye molecules absorb some light, resulting in a certain color in the film. This state has low transmittance and is defined as the dark state. When an electric field is applied, the liquid crystal molecules in the liquid crystal droplets align uniformly along the direction of the electric field, and the dye molecules also align neatly with the liquid crystal matrix. Light passes through, and the dye-modified PDLC appears transparent with higher transmittance, defined as the bright state. Because light passing through the long and short axes of the dye molecules is absorbed and transmitted respectively, its transmittance is relatively low; that is, less light passes through dye-modified PDLC than ordinary PDLC. The ratio of the transmittance of the bright state to that of the dark state is the contrast ratio of the PDLC.

[0004] Current PDLC dimming films still suffer from the following problems: low contrast ratio. With improved contrast ratios, the visual transition between the transparent and dark states of dye-based PDLCs becomes more effective. Currently, the contrast ratio of dye-based PDLCs is around 10, resulting in poor visual quality and poor sunlight blocking in the dark state. There is a need to develop a high-contrast dye-based PDLC dimming film with a contrast ratio ≥20, which would effectively block sunlight in the dark while allowing clear visibility of the outside scenery in the bright state, thus meeting the application requirements in automotive windows. Current PDLC dimming films are severely limited in terms of contrast ratio improvement due to constraints imposed by factors such as ITO substrate, dichroic dyes, and liquid crystal compositions, making it difficult to achieve excellent black levels and high contrast effects.

[0005] Furthermore, current PDLC dimming films have poor resistance to sunlight. After prolonged exposure to sunlight, the contrast and color difference of dye-based PDLC dimming films change significantly. When used in outdoor or extreme environments such as vehicle roofs and building curtain walls, PDLC dimming films will inevitably be exposed to prolonged sunlight. The ultraviolet rays in sunlight can easily cause the degradation of dyes and polymer matrices, which in turn affects the fading or color drift of PDLC dimming films and affects the user experience. Therefore, it is crucial to improve the stability of contrast and color difference changes of dye-based PDLC dimming films after prolonged exposure to sunlight. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a dye-modified PDLC dimming film and its applications. The dye-modified PDLC dimming film not only possesses advantages such as a dark-state transmittance of 0.00%~1.00%, a bright-state transmittance of 2.00%~20.00%, and a contrast ratio greater than or equal to 20, but also maintains high contrast and low color difference changes after prolonged exposure to sunlight, exhibiting excellent sunlight tolerance. It can be widely applied in fields such as smart glass for automobiles, high-speed trains, aircraft, and buildings.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a dye PDLC dimming film, which comprises two transparent ITO conductive films and a dye PDLC composition sandwiched in between; wherein the transparent ITO conductive films have a transmittance of 10.00%~70.00%, an a value of -5~5, and a b value of -4~8; the dye PDLC dimming film has a contrast ratio ≥20, a dark transmittance of 0.00%~1.00%, and a bright transmittance of 2.00%~20.00%.

[0009] Compared with the prior art, the present invention has the following advantages:

[0010] (1) By selecting specific two-layer transparent ITO conductive film and combining it with a dye PDLC composition, the present invention can produce a dye PDLC dimming film with a dark state transmittance of 0.00%~1.00% and a bright state transmittance of 2.00%~20.00% after UV curing. The contrast ratio of the dye PDLC dimming film is ≥20.

[0011] (2) The dye PDLC dimming film provided by the present invention can maintain a high contrast and a low color difference after long-term sunlight exposure. It has excellent resistance to sunlight and can be widely used in the fields of smart glass for automobiles, high-speed rail, airplanes or buildings.

[0012] It should be further explained that the a and b values ​​represent the color space coordinates of the color.

[0013] Preferably, the transparent ITO conductive film has a transmittance of 30.00%~60.00%, a haze of ≤1.00%, an a value of -3~3, a b value of -2~6, a sheet resistance of 5~250Ω, and a thickness of 50~250µm.

[0014] Preferably, the dye PDLC composition comprises the following raw material components in parts by weight: 30-70 parts of dichroic dye liquid crystal, 30-70 parts of photocurable adhesive, and 0.2-2 parts of spacers.

[0015] More preferably, the dye PDLC composition comprises the following raw material components in parts by weight: 34-66 parts of dichroic dye liquid crystal, 34-66 parts of photocurable adhesive, and 0.3-1.5 parts of spacers.

[0016] Preferably, the dichroic dye liquid crystal comprises the following raw material components in the following mass percentages: 1%~10% dichroic dye and 90%~99% nematic liquid crystal.

[0017] Preferably, the clearing point of the nematic liquid crystal is ≥110°C, the optical anisotropy is ≥0.2, and the dielectric anisotropy is ≥10.

[0018] Preferably, the dichroic dye comprises at least one of the compounds shown in formulas I to VII:

[0019] Formula I, Formula II

[0020] Formula III Formula IV

[0021] Formula V, Formula VI

[0022] Equation VII;

[0023] in, ~ Each independently selected , , , or Any one of them;

[0024] R1~R 14 Each is independently selected from H, a straight-chain or branched alkyl group with 1 to 12 carbon atoms, an alkoxy group, an alkyl carbonyl group, an alkoxy carbonyl group, or a straight-chain or branched alkenyl or alkenoxy group with 2 to 12 carbon atoms;

[0025] X1, X2, X3, and X4 are each independently selected from amino or hydroxyl groups.

[0026] More preferably, the compound represented by Formula I is selected from at least one of Formula I-1 or Formula I-2:

[0027] Formula I-1, Formula I-2.

[0028] More preferably, the compound represented by Formula II is selected from at least one of Formula II-1 or Formula II-2:

[0029] Formula II-1

[0030] Formula II-2.

[0031] More preferably, the compound represented by Formula III includes .

[0032] More preferably, the compound represented by formula IV is selected from at least one of formula IV-1 or formula IV-2:

[0033] Formula IV-1

[0034] Formula IV-2.

[0035] More preferably, the compound represented by formula V is selected from at least one of formula V-1, formula V-2, or V-3:

[0036] Formula V-1 Formula V-2

[0037] Formula V-3.

[0038] More preferably, the compound represented by formula VI is selected from at least one of formula VI-1, formula VI-2, or formula VI-3:

[0039] Formula VI-1 Formula VI-2

[0040] Formula VI-3.

[0041] More preferably, the compound represented by formula VII is selected from at least one of formula VII-1, formula VII-2, or formula VII-3:

[0042] Equation VII-1 Equation VII-2

[0043] VII-3.

[0044] Preferably, the nematic liquid crystal comprises at least one of the compounds shown in Formulas 1 to 3;

[0045] Formula 1 Formula 2

[0046] Formula 3.

[0047] Among them, R 15 R 16 and R 17 Each is independently selected from alkyl groups of 1 to 10 carbon atoms or alkoxy groups of 1 to 10 carbon atoms;

[0048] , and Each independently selected or ;

[0049] and Each independently selected , or ;

[0050] Y1 and Y2 are each independently selected from cyano, fluorine, or alkyl groups with 1 to 10 carbon atoms;

[0051] m represents 0, 1, or 2. When m is 2, or They are either the same or different independently.

[0052] Preferably, the nematic liquid crystal comprises the following components in the following mass percentages: 60%~80% of the compound shown in Formula 1, 5%~25% of the compound shown in Formula 2, and 5%~25% of the compound shown in Formula 3.

[0053] More preferably, the nematic liquid crystal comprises the following components in the following mass percentages: 70%~80% of the compound shown in Formula 1, 10%~15% of the compound shown in Formula 2, and 10%~15% of the compound shown in Formula 3.

[0054] More preferably, the compound of formula 1 is selected from at least one of formulas 1-1 to 1-13:

[0055] Formula 1-1 Formula 1-2

[0056] Formula 1-3 Formula 1-4

[0057] Formulas 1-5 Formulas 1-6

[0058] Formulas 1-7 Formulas 1-8

[0059] Formulas 1-9 Formula 1-10

[0060] Formula 1-11 Equation 1-12

[0061] Equation 1-13.

[0062] More preferably, the compound represented by Formula 2 is selected from at least one of Formula 2-1, Formula 2-2, or Formula 2-3:

[0063] Formula 2-1

[0064] Equation 2-2

[0065] Equation 2-3.

[0066] More preferably, the compound represented by Formula 3 is selected from at least one of Formula 3-1 or Formula 3-2:

[0067] Formula 3-1

[0068] Equation 3-2.

[0069] Preferably, the photocurable adhesive comprises the following raw material components in the following mass percentages: 10%~25% acrylate prepolymer, 72%~85% acrylate diluent, 0.5%~3% additives, and 1%~3% photoinitiator.

[0070] More preferably, the acrylate prepolymer includes at least one of aliphatic polyurethane acrylate, alicyclic polyurethane acrylate, aromatic polyurethane acrylate, polyester acrylate, polyether-modified acrylate, or epoxy acrylate.

[0071] More preferably, the acrylate diluent is selected from at least one of the following: dodecyl acrylate, isodecanyl acrylate, tetradecyl methacrylate, acrylomorpholine, dicyclopentenyl acrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, benzyl acrylate, isobornyl acrylate, o-phenylphenoxyethyl acrylate, isobornyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, ethoxylated 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, pentaerythritol triacrylate, 1,9-nonanediol diacrylate, 1,6-hexanediol diacrylate, (ethoxy)bisphenol A diacrylate, pentaerythritol tetraacrylate, pentaerythritol tetra-3-mercaptopropionate, or ethoxylated trimethylolpropane triacrylate.

[0072] More preferably, the additive includes at least one of a silane coupling agent or a phosphate ester modifier.

[0073] More preferably, the additive includes a phosphate ester modifier.

[0074] More preferably, the phosphate ester modifier is PM2072 from Guangzhou Jingde Chemical Materials Co., Ltd.

[0075] Preferably, the photoinitiator includes at least one of photoinitiator TPO, photoinitiator 819, photoinitiator 184, ITX, photoinitiator 907, photoinitiator TPO-L, photoinitiator 1173, or photoinitiator 784.

[0076] More preferably, the photoinitiator is selected from at least one of photoinitiator TPO or photoinitiator 819.

[0077] Preferably, the spacer is at least one of polymethyl methacrylate, polystyrene, or silica.

[0078] More preferably, the spacer particles have a particle size of 10~30μm and are white or black in color.

[0079] More preferably, the spacer particles have a particle size of 10~20μm and are black in color.

[0080] The preparation method of the dye PDLC composition includes the following steps:

[0081] The weighed dichroic dye liquid crystal, photocurable adhesive and spacer are mixed evenly to obtain the dye PDLC composition.

[0082] For example, the nematic liquid crystal needs to be heated to 90°C to melt before use.

[0083] For example, the light-curing adhesive requires that all raw material components be stirred and dissolved evenly at room temperature before use.

[0084] It should be further noted that the dye PDLC dimming film is prepared by UV curing.

[0085] Preferably, the UV curing light intensity irradiation energy is 3000~30000 mJ / cm². 2 .

[0086] More preferably, the UV curing light intensity irradiation energy is 10000~25000 mJ / cm². 2 .

[0087] This invention provides the application of the above-mentioned dye PDLC dimming film in the preparation of smart glass for automobiles, high-speed trains, aircraft or buildings. Detailed Implementation

[0088] To make the objectives, technical solutions, and advantages of the present invention clearer, the invention will be clearly and completely described below in conjunction with specific embodiments. Many specific details are set forth in the following description in order to provide a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the present disclosure, and not all embodiments.

[0089] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0090] The technical solution of the present invention will be described below with reference to some specific embodiments:

[0091] In this invention, unless otherwise specified, the preparation methods are all conventional methods, and the raw materials used can be obtained from publicly available commercial sources unless otherwise specified. All percentage contents refer to mass percentages (wt%), and the temperature is in degrees Celsius (°C). The specific meanings of other symbols and test conditions are as follows:

[0092] Cp represents the liquid crystal clearing point (°C), measured by DSC quantitative method;

[0093] Δn represents optical anisotropy, no is the refractive index of ordinary light, ne is the refractive index of extraordinary light, and the test conditions are 25±2℃, 589nm, and Abbe refractometer test.

[0094] Δε represents dielectric anisotropy, Δε = ε ∥ -ε ⊥ , where ε ∥ ε is the dielectric constant parallel to the molecular axis. ⊥The dielectric constant is perpendicular to the molecular axis. The test conditions are 25±0.5℃, TN7.0-R box, INSTEC:ALCT CUST 4C test.

[0095] The color testing method is as follows: A spectrophotometer, model CM-36dG, is used to test the Lab value of the sample. The L value represents the brightness of the color, with brightness gradually increasing from 0 to 100. The a value represents red and green; a value > 0 represents red, and the larger the value, the deeper the red; a value < 0 represents green, and the smaller the value, the deeper the green. The b value represents yellow and blue; b value > 0 represents yellow, and the larger the value, the deeper the yellow; b value < 0 represents blue, and the smaller the value, the deeper the blue. The test conditions are: room temperature, D65 light source, test angle: 10 degrees; the measurement conditions comply with CIENo.15 (2004), ASTM E1164, DIN 5033 Teil7, and JISZ 8722 condition "G" standard.

[0096] The haze and transmittance test methods are as follows: use a color spectrum TH-110 haze meter to test the haze and transmittance of the PDLC dimming film in the dark state (0V without power) and the transparent state (48V with power), and calculate the contrast ratio of the PDLC dimming film (transparent state transmittance / dark state transmittance), where the transparent state is also called the bright state.

[0097] In Examples 6-8, Comparative Examples 4 and 6 of the present invention, two characteristic ITO conductive films ① were used: the film transmittance was 53.20%, the haze was 0.63%, the color a value was -0.9, the color b value was -1.0, the sheet resistance was 97.7Ω, and the thickness was 188μm; in Example 9, two characteristic ITO conductive films ② were used: the film transmittance was 35.02%, the haze was 1.00%, the color a value was -0.85, the color b value was 0.07, the sheet resistance was 85Ω, and the thickness was 188μm.

[0098] Comparative Examples 1, 3, and 5 use two layers of ordinary ITO conductive film ③: the film transmittance is 88.10%, haze is 0.53%, a value is -0.15, b value is 1.29, sheet resistance is 125.0Ω, and thickness is 188μm.

[0099] Comparative Example 2 uses a characteristic ITO conductive film ① (film transmittance of 53.20%, haze of 0.63%, color a value of -0.9, b value of -1.0, sheet resistance of 97.7Ω, and thickness of 188μm) and a common ITO conductive film ③ (film transmittance of 88.10%, haze of 0.53%, a value of -0.15, b value of 1.29, sheet resistance of 125.0Ω, and thickness of 188μm).

[0100] The liquid crystal monomer structures provided in the embodiments or comparative examples of the present invention are represented by codes. The code representation methods for liquid crystal ring structures, end groups, and linking groups are shown in Tables 1-2 below.

[0101] Table 1. Code table for structure

[0102]

[0103] Table 2. Correspondence codes between terminal groups and linking groups

[0104]

[0105] For example:

[0106] Its code is CZP-3-N;

[0107] Its code is CC-3-V;

[0108] Its code is CP-3-O2;

[0109] Its code is CCP-V-1;

[0110] Example 1

[0111] This embodiment provides a nematic liquid crystal (denoted as LC1), the specific composition of which is shown in Table 3:

[0112] Table 3. Composition and performance parameters of nematic liquid crystal LC1

[0113]

[0114] Example 2

[0115] This embodiment provides a dichroic dye liquid crystal, the specific composition of which is shown in Table 4:

[0116] Table 4

[0117]

[0118] Example 3

[0119] This embodiment provides a dichroic dye liquid crystal, the specific composition of which is shown in Table 5:

[0120] Table 5

[0121]

[0122] Example 4

[0123] This embodiment provides a dichroic dye liquid crystal, the specific composition of which is shown in Table 6:

[0124] Table 6

[0125]

[0126] Example 5

[0127] This embodiment provides a dichroic dye liquid crystal, the specific composition of which is shown in Table 7:

[0128] Table 7

[0129]

[0130] Example 6

[0131] This embodiment provides a dye PDLC dimming film, in which a dye PDLC composition is dropped between two layers of transparent ITO conductive film, and under ultraviolet light, at a concentration of 25000 mJ / cm²... 2 Photocuring with light intensity irradiation energy yields dye PDLC dimming film;

[0132] The two-layer transparent ITO conductive film has a transmittance of 53.20%, a haze of 0.63%, a color value of -0.9, a color value of -1.0, a sheet resistance of 97.7Ω, and a thickness of 188μm.

[0133] Specifically, in the dye PDLC composition, the mass ratio of dichroic dye liquid crystal, photocurable adhesive, and spacer is 34.5:64:1.5;

[0134] The dichroic dye liquid crystal is the dichroic dye liquid crystal provided in Example 2;

[0135] The UV-curable adhesive comprises the following raw material components in the following weight percentages: 12% polyurethane acrylate, 13% acryloylmorpholine, 5% isodecanyl acrylate, 13% isobornyl acrylate, 4% hydroxypropyl methacrylate, 5% hydroxypropyl acrylate, 10% dodecyl acrylate, 5% benzyl acrylate, 5% o-phenylphenoxyethyl acrylate, 5% 1,4-butanediol diacrylate, 5.5% ethoxylated 1,6-hexanediol diacrylate, 5% (ethoxy)bisphenol A diacrylate, 5% pentaerythritol tetraacrylate, 1.5% pentaerythritol tetra-3-mercaptopropionate, 3% phosphate modifier, 1.5% photoinitiator TPO, and 1.5% photoinitiator 819.

[0136] The spacers are black, made of polymethyl methacrylate, and have a particle size of 20 μm.

[0137] The preparation method of the dye PDLC composition includes the following steps:

[0138] Weigh each component of the UV-curable adhesive according to the specified ratio, and stir at room temperature until dissolved and homogeneous to obtain the UV-curable adhesive;

[0139] Weigh out each component of the dichroic dye liquid crystal separately, heat to 90°C and stir until homogeneous to obtain the dichroic dye liquid crystal.

[0140] The photocurable adhesive, dichroic dye liquid crystal, and spacer are mixed and stirred evenly to obtain a dye PDLC composition.

[0141] Example 7

[0142] This embodiment provides a dye PDLC dimming film, which differs from Embodiment 6 in that: in the dye PDLC composition, the mass ratio of dichroic dye liquid crystal, photocurable adhesive and spacers is 39.5:59:1.5; the dichroic dye liquid crystal is the dichroic dye liquid crystal provided in Embodiment 3;

[0143] The other components and preparation methods are the same as in Example 6.

[0144] Example 8

[0145] This embodiment provides a dye PDLC dimming film, which differs from Embodiment 6 in that: in the dye PDLC composition, the mass ratio of dichroic dye liquid crystal, photocurable adhesive and spacers is 39.8:59.7:0.5; the dichroic dye liquid crystal is the dichroic dye liquid crystal provided in Embodiment 4;

[0146] The other components and preparation methods are the same as in Example 6.

[0147] Example 9

[0148] This embodiment provides a dye PDLC dimming film, which differs from Embodiment 6 in that: in the two layers of transparent ITO conductive film, the film material has a transmittance of 35.02%, a haze of 1.00%, an a value of -0.85, a b value of 0.07, a sheet resistance of 85.0Ω, and a thickness of 188μm;

[0149] In the dye PDLC composition, the mass ratio of dichroic dye liquid crystal, photocurable adhesive, and spacer is 34.5:64:1.5;

[0150] The dichroic dye liquid crystal is the dichroic dye liquid crystal provided in Example 5;

[0151] The other components and preparation methods are the same as in Example 6.

[0152] Comparative Example 1

[0153] This comparative example provides a dye PDLC dimming film, which differs from Example 6 in that: the two transparent ITO conductive films have a transmittance of 88.10%, a haze of 0.53%, an a value of -0.15, a b value of 1.29, a sheet resistance of 125.0Ω, and a thickness of 188μm;

[0154] The other components and preparation methods are the same as in Example 6.

[0155] Comparative Example 2

[0156] This comparative example provides a dye PDLC dimming film, which differs from Example 6 in that: one layer of transparent ITO conductive film has a transmittance of 53.20%, a haze of 0.63%, a color a value of -0.9, a b value of -1.0, a sheet resistance of 97.7Ω, and a thickness of 188μm; the other layer of transparent ITO conductive film has a transmittance of 88.10%, a haze of 0.53%, an a value of -0.15, a b value of 1.29, a sheet resistance of 125.0Ω, and a thickness of 188μm.

[0157] The other components and preparation methods are the same as in Example 6.

[0158] Comparative Example 3

[0159] This comparative example provides a dye PDLC dimming film, which differs from Example 6 in that: no dichroic dye is added to the dye PDLC composition, and the mass ratio of photocurable adhesive, LC1 and spacers is 34.5:64:1.5.

[0160] The two-layer transparent ITO conductive film has a transmittance of 88.10%, a haze of 0.53%, an a value of -0.15, a b value of 1.29, a sheet resistance of 125.0Ω, and a thickness of 188μm.

[0161] The other components and preparation methods are the same as in Example 6.

[0162] Comparative Example 4

[0163] This comparative example provides a dye PDLC dimming film, which differs from Example 6 in that: no dichroic dye is added to the dye PDLC composition, and the mass ratio of photocurable adhesive, LC1 and spacers is 34.5:64:1.5.

[0164] The other components and preparation methods are the same as in Example 6.

[0165] Comparative Example 5

[0166] This comparative example provides a dye PDLC dimming film, which differs from Example 6 in that: the nematic liquid crystal LC1 is replaced with an equal amount of nematic liquid crystal LC2, the specific composition of which is shown in Table 8.

[0167] Table 8. Composition and performance parameters of nematic liquid crystal LC2

[0168]

[0169] In the dye PDLC composition, the mass ratio of dichroic dye liquid crystal, photocurable adhesive, and spacer is 34.5:64:1.5;

[0170] The two-layer transparent ITO conductive film has a transmittance of 88.10%, a haze of 0.53%, an a value of -0.15, a b value of 1.29, a sheet resistance of 125.0Ω, and a thickness of 188μm.

[0171] The other components and preparation methods are the same as in Example 6.

[0172] Comparative Example 6

[0173] This comparative example provides a dye PDLC dimming film, which differs from Example 6 in that: LC1 is replaced with an equal amount of LC2; and in the dye PDLC composition, the mass ratio of dichroic dye liquid crystal, photocurable adhesive and spacers is 34.5:64:1.5.

[0174] The other components and preparation methods are the same as in Example 6.

[0175] Example of effect

[0176] The performance of the dye PDLC dimming films prepared in Examples 6-9 and Comparative Examples 1-6 were tested, and the test indicators and results are shown in Tables 9-12.

[0177] Table 9. Test results of haze, transmittance and contrast of dye PDLC dimming film

[0178]

[0179] The Lab value test results of the dye PDLC dimming film are shown in Table 10 below:

[0180] Table 10 Test results of Lab value of PDLC dimming film

[0181]

[0182] Xenon lamp irradiation test: The dye PDLC dimming films prepared in Examples 6-9 and Comparative Examples 1-6 were placed in a xenon lamp aging chamber to simulate sunlight irradiation (irradiation intensity of 1120 W / m²). 2 After aging at 50℃ for 1000 hours, the haze, transmittance, and Lab value of the sample were measured again, and the color difference ΔE was calculated, where: ΔE=[(ΔL*)] 2 +(Δa*) 2 +(Δb*) 2 ] 1 / 2 ΔL*=L0* L1*;Δ a*=a0* a1*;Δ b*=b0* b1*; The larger the change in ΔE, the greater the color difference before and after aging. When ΔE < 2, it is generally imperceptible to the human eye, thus meeting the color difference change requirement. The contrast ratio (initial) is the data before aging, and the contrast ratio (final) is the data after aging. The test calculation results are shown in Tables 11-12:

[0183] Table 11 Test results of haze, transmittance and contrast of PDLC dimming film after 1000h xenon lamp aging.

[0184]

[0185] Table 12 Test results of Lab value and color difference ΔE of PDLC dimming film after 1000h xenon lamp aging.

[0186]

[0187] As shown in Tables 9-12, compared to Comparative Examples 1-6, the dye-modified PDLC films obtained in Examples 6-9 have lower 48V transmittance and even lower 0V transmittance. Specifically, the dark-state transmittance of the dye-modified PDLC films obtained in Examples 6-9 is in the range of 0.00%~1.00%, the bright-state transmittance is in the range of 2.00%~20.00%, and the contrast ratio is above 20. Moreover, they can maintain high contrast ratio and low color difference change after long-term sunlight aging of 1000h, demonstrating excellent resistance to sunlight. In Example 9, the test data for 0V transmittance of the dye-modified PDLC film before and after aging are both 0.00%. According to the theoretical calculation formula contrast ratio = transmittance in the light state / transmittance in the dark state, the theoretical contrast ratio of Example 9 before and after aging is positive infinity (+∞).

[0188] Comparative Example 1 uses two different transparent ITO conductive films than Example 6. Comparative Example 2 uses one different transparent ITO conductive film than Example 6. Due to the different transparent ITO conductive films, the contrast of the dye PDLC dimming film is reduced, and the contrast remains low and the color difference changes significantly after long-term sunlight aging. Comparative Example 3 uses two different transparent ITO conductive films than Example 6 and does not add dichroic dyes. Compared with Example 6, Comparative Example 4 does not add dichroic dyes. Comparative Examples 3 and 4 have very low contrast, and the contrast remains low after long-term sunlight aging. Compared with Example 6, Comparative Example 5 uses a nematic liquid crystal and a transparent ITO conductive film instead of a nematic liquid crystal. The contrast remains low, and the contrast remains low and the color difference changes significantly after long-term sunlight aging. Although Comparative Example 6 uses the transparent ITO conductive film provided in Example 6, it uses a nematic liquid crystal instead of a nematic liquid crystal. This also results in a low contrast of the prepared dye PDLC dimming film, which cannot obtain a high-contrast dye PDLC dimming film. Furthermore, the contrast remains low and the color difference changes significantly after long-term sunlight aging.

[0189] In summary, the dye PDLC dimming film provided in this embodiment of the invention not only has the advantages of dark state transmittance of 0.00%~1.00%, bright state transmittance of 2.00%~20.00%, and contrast ratio ≥20, but also maintains high contrast and low color difference change after long-term sunlight exposure. It has excellent sunlight tolerance and can be widely used in fields such as smart glass for automobiles, high-speed rail, airplanes, or buildings.

[0190] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A dye-based PDLC dimming film, characterized in that, The dye-modified PDLC dimming film comprises two layers of transparent ITO conductive films and a dye-modified PDLC composition sandwiched in between; wherein, the two transparent ITO conductive films each have a transmittance of 35.02%~53.20%, a haze of ≤0.63%~1.00%, an a value of -0.9~-0.85, and a b value of -1.0~0.07; the dye-modified PDLC dimming film has a contrast ratio ≥20, a dark transmittance of 0.00%~1.00%, and a bright transmittance of 2.00%~20.00%; The dye PDLC dimming film has a strength of 10000~25000 mJ / cm 2 Obtained by UV curing with light intensity irradiation energy; The dye PDLC composition comprises a dichroic dye liquid crystal, a photocurable adhesive, and spacers in a mass ratio of (30~70):(30~70):(0.2~2); The dichroic dye liquid crystal comprises the following raw material components in the following mass percentages: 1%~10% dichroic dye and 90%~99% nematic liquid crystal; The clearing point of the nematic liquid crystal is ≥110℃, the optical anisotropy is ≥0.2, and the dielectric anisotropy is ≥10. The nematic liquid crystal comprises the following components in the following mass percentages: 60%~80% of the compound shown in Formula 1, 5%~25% of the compound shown in Formula 2, and 5%~25% of the compound shown in Formula 3; The compound of Formula 1 is selected from at least one of Formulas 1-1 to 1-13: Formula 1-1 Formula 1-2 Formula 1-3 Formula 1-4 Formulas 1-5 Formulas 1-6 Formulas 1-7 Formulas 1-8 Formulas 1-9 Formula 1-10 Formula 1-11 Equation 1-12 Equation 1-13; The compound represented by Formula 2 is selected from at least one of Formula 2-1, Formula 2-2, or Formula 2-3: Formula 2-1 Equation 2-2 Equation 2-3; The compound shown in Formula 3 is selected from at least one of Formula 3-1 or Formula 3-2: Formula 3-1 Equation 3-2.

2. The dye PDLC dimming film as described in claim 1, characterized in that, The transparent ITO conductive film has a sheet resistance of 5~250Ω and a thickness of 50~250µm.

3. The dye PDLC dimming film according to claim 1, characterized in that, The dichroic dye comprises at least one of the compounds shown in Formulas I to VII: Formula I, Formula II Formula III Formula IV Formula V, Formula VI Equation VII; in, ~ Each independently selected , , , or Any one of them; R1~R 14 Each is independently selected from H, a straight-chain or branched alkyl group with 1 to 12 carbon atoms, an alkoxy group, an alkyl carbonyl group, an alkoxy carbonyl group, or a straight-chain or branched alkenyl or alkenoxy group with 2 to 12 carbon atoms; X1, X2, X3, and X4 are each independently selected from amino or hydroxyl groups.

4. The dye PDLC dimming film as described in claim 3, characterized in that, The compound represented by Formula I is selected from at least one of Formula I-1 or Formula I-2: Equation I-1, Equation I-2; The compound represented by Formula II is selected from at least one of Formula II-1 or Formula II-2: Formula II-1 Formula II-2; The compounds represented by Formula III include ; The compound represented by formula IV is selected from at least one of formula IV-1 or formula IV-2: Formula IV-1 Formula IV-2; The compound represented by formula V is selected from at least one of formula V-1, formula V-2, or V-3: Formula V-1 Formula V-2 Formula V-3; The compound represented by formula VI is selected from at least one of formula VI-1, formula VI-2, or formula VI-3: Formula VI-1、 Formula VI-2、 Formula VI-3; The compound represented by formula VII is selected from at least one of formula VII-1, formula VII-2, or formula VII-3: Equation VII-1 Equation VII-2 VII-3。 5. The application of the dye PDLC dimming film as described in any one of claims 1 to 4 in the preparation of smart glass for automobiles, high-speed trains, airplanes or buildings.

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