High contrast anthraquinone dye pdlc composition and light control film

Abstract

The present application relates to the technical field of light control film, and in particular to a high-contrast anthraquinone dye PDLC composition and light control film, which comprises dichroic dye liquid crystal, photocuring glue and spacer, wherein the dichroic dye liquid crystal comprises nematic liquid crystal and dichroic dye, and the dichroic dye at least comprises one compound selected from the following formula I, formula II, formula III, formula IV or formula V. The present application introduces a new type of anthraquinone dichroic dye with optimized molecular configuration, overcomes the defects of the existing dye in the degree of orientation and solubility, and improves the contrast of the anthraquinone dye in the liquid crystal. The PDLC light control film prepared from the composition has high contrast and excellent thermal / hue stability.

Description

Technical Field

[0001] This invention relates to the field of dimming film technology, and more particularly to a high-contrast anthraquinone dye PDLC composition and dimming film. Background Technology

[0002] Polymer-dispersed liquid crystal (PDLC) dimming films, as an electrically controlled dimming material, have been widely used in architectural glass, privacy protection, display devices, and automotive sunroofs due to their advantages such as flexibility, large-area production capability, and fast response speed. PDLC technology is mainly divided into traditional PDLC without dyes and D-PDLC with dichroic dyes. D-PDLC introduces dichroic dyes into its formulation, utilizing the orientation characteristics of dye molecules to achieve light absorption, thus achieving a high dark state when power is off and high light transmittance when power is applied.

[0003] D-PDLC compositions typically consist of nematic liquid crystals, dichroic dyes, UV-curable adhesives, photoinitiators, and spacer particles. The composition and ratio of these components play a decisive role in the photoelectric properties of the final dimming film. Existing D-PDLCs mainly employ azo or anthraquinone dichroic dyes. While azo dyes offer high color saturation, they generally suffer from poor photostability and are prone to fading, severely limiting the outdoor applications and lifespan of the dimming film. Existing anthraquinone dyes, although exhibiting better photostability, suffer from insufficient solubility in liquid crystals or UV-curable adhesives and generally low overall contrast.

[0004] To achieve high contrast, dye molecules in liquid crystals must possess a high degree of orientation. However, many existing dye structures are designed with a lack of prominent long axes in their molecular configurations, or with the long axis forming an angle with the direction of the electronic transition dipole moment, resulting in insignificant anisotropy after liquid crystal alignment. This makes it difficult for the light absorption difference (i.e., contrast) between the dark (OFF) and bright (ON) states of PDLC films to meet the requirements of high-end applications. Summary of the Invention

[0005] The purpose of this invention is to provide a high-contrast anthraquinone dye PDLC composition. By introducing a novel anthraquinone dichroic dye with optimized molecular configuration, the defects of existing dyes in terms of orientation and solubility are overcome, and the contrast of anthraquinone dye in liquid crystal is improved.

[0006] The present invention also provides a PDLC dimming film prepared from the composition, which has high contrast and excellent thermal / color stability.

[0007] To achieve the above objectives, the first aspect of the present invention provides a high-contrast anthraquinone dye PDLC composition, comprising, by weight percentage: dichroic dye liquid crystal, photocurable adhesive and spacers; The dichroic dye liquid crystal comprises a nematic liquid crystal and a dichroic dye; the dichroic dye comprises at least one compound selected from the following formulas I, II, III, IV or V: Formula I, Formula II, Formula III, Formula IV, Formula V, to Each represents independently , , , , , or ; X1, X3, X4, X5, X8, X 11 X 12 X 15 Each can independently represent -H, -NH2 (amino), -NHCH3 (methylamino), -NHC4H9 (butanamino), -NAr (arylamino), -OH, or halogen; X2, X6, X7, X9, X 10 X 13 X 14 X 16 -X 20 Each can be independently represented as -OCH2- (oxymethylene), -NHCH2- (aminomethylene), -OCF2- (oxydifluoromethylene), -SCH2- (thiomethylene), or -OCO- (ester group); R1-R4, R6-R9, R 12 -R 15 R 18 -R 21 R 25 -R 28 Each can independently represent -H, -CH3, halogen, or one of the following groups: , , , , In this context, “” indicates the connection position with other atoms; R5, R 10 R 11 R 16 R 17 R22 -R 24 R 29 -R 32 Each can independently represent -H, straight-chain or branched alkyl, alkoxy, alkyl carbonyl, or alkoxy carbonyl groups with 1 to 12 carbon atoms; Z1-Z 12 Each can independently represent a single bond, a methylene oxide group, or an -OCO- (ester group); each 'al' independently represents 0 or 1.

[0008] Furthermore, in formulas I, II, III, IV, or V: to Each represents independently or ; X1, X3, X4, X5, X8, X 11 X 12 X 15 Each can independently represent -H, -NH2 (amino), or -OH; X2, X6, X7, X9, X 10 X 13 X 14 X 16 -X 20 Each can be independently represented as -OCH2- (oxymethylene), -NHCH2- (aminomethylene), or -SCH2- (thiomethylene). R1-R4, R6-R9, R 12 -R 15 R 18 -R 21 R 25 -R 28 Each can be independently represented as -H or -CH3; R5, R 10 R 11 R 16 R 17 R 22 -R 24 R 29 -R 32 Each can independently represent a straight-chain or branched alkyl group with -H and 1 to 12 carbon atoms; Z1-Z 12 Indicates a single key; each 'al' independently represents 0 or 1.

[0009] Preferably, the compound represented by Formula I is selected from any one or more of the compounds represented by Formulas I-1 to I-8:

[0010] Preferably, the compound represented by Formula II is selected from any one or more of the compounds represented by Formulas II-1 to II-6:

[0011] Preferably, the compound represented by Formula III is selected from any one or two of the compounds represented by Formulas III-1 and III-2:

[0012] Preferably, the compound represented by Formula IV is selected from any one or two of the compounds represented by Formulas IV-1 to IV-2:

[0013] Preferably, the compound represented by formula V is selected from any one or more of the compounds represented by formulas V-1 to V-4:

[0014] Furthermore, taking the total mass of the dichroic dye liquid crystal and the photocurable adhesive as 100%, the mass ratio of the dichroic dye liquid crystal to the photocurable adhesive is 35~65:65~35, and the content of the spacer is 0.3-1.5% of the total mass of the dichroic dye liquid crystal and the photocurable adhesive. The dichroic dye liquid crystal comprises, by mass percentage, 1-10% of the dichroic dye and 90-99% of the nematic liquid crystal; wherein the clearing point of the nematic liquid crystal is ≥90℃, the optical anisotropy is >0.18, and the dielectric anisotropy is >5.

[0015] Preferably, the clearing point of the nematic liquid crystal is >100°C, the optical anisotropy is >0.2, and the dielectric anisotropy is >8.

[0016] Furthermore, the UV-curable adhesive, calculated by weight percentage, comprises: Polyurethane acrylate oligomers: 10-24 wt% Reactive diluent: 74.5-84.5 wt% Additives: 0.5-3 wt% Photoinitiator: 1-3 wt%.

[0017] Furthermore, the polyurethane acrylate oligomer is selected from one or more of the following: aliphatic polyurethane acrylate, alicyclic polyurethane acrylate, aromatic polyurethane acrylate, polyester acrylate, polyether-modified acrylate, and epoxy acrylate.

[0018] Preferably, the polyurethane acrylate oligomer is an aliphatic polyurethane acrylate.

[0019] Further, the reactive diluent is selected from one or more of the following: dodecyl acrylate, isodecyl acrylate, dicyclopentenyl acrylate, benzyl acrylate, isobornyl acrylate, o-phenylphenoxyethyl acrylate, 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, ethoxylated trimethylolpropane triacrylate, tetradecyl methacrylate, hydroxybutyl methacrylate, isobornyl methacrylate, hydroxypropyl methacrylate, acrylomorpholine, N,N-dimethylacrylamide, and N-hydroxyethylacrylamide.

[0020] Preferably, the reactive diluent is selected from one or more of the following: dodecyl acrylate, isodecanyl acrylate, dicyclopentenyl acrylate, ethoxylated 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, acryloylmorpholine, and N,N-dimethylacrylamide.

[0021] Furthermore, the additive is selected from one or two of silane coupling agents and phosphate ester modifiers.

[0022] Preferably, the auxiliary agent is a phosphate ester modifier.

[0023] Furthermore, the photoinitiator is selected from one or more of photoinitiator TPO, photoinitiator 819, photoinitiator 184, photoinitiator ITX, photoinitiator 907, photoinitiator TPO-L, photoinitiator 1173 and photoinitiator 784.

[0024] Preferably, the photoinitiator is selected from photoinitiator TPO and / or photoinitiator 819.

[0025] Furthermore, the spacer is a black or white microsphere with a particle size of 10-30 μm, and the microsphere is made of acrylic polymer, polystyrene or silica.

[0026] Preferably, the spacer particle size is 10-20 μm.

[0027] Preferably, the spacer is black.

[0028] A second aspect of the present invention provides a dye PDLC dimming film, the dimming film comprising two conductive films and a dye PDLC layer disposed between the two conductive films, which is formed by UV curing the above-mentioned high-contrast anthraquinone dye PDLC composition.

[0029] Furthermore, the conductive film has a transmittance of 10-90%, a sheet resistance of 5-250Ω, and a thickness of 50-250μm.

[0030] Preferably, the conductive film has a transmittance of 30-90%, a sheet resistance of 80-150Ω, and a thickness of 100-200μm.

[0031] Furthermore, the irradiation dose for UV curing is 3-100 J / cm². 2 .

[0032] Preferably, the UV curing light intensity irradiation dose is 20-50 J / cm². 2 .

[0033] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention employs novel anthraquinone dichroic dyes with specific structures shown in Formulas I to V. These dyes, through molecular configuration optimization, exhibit high orientation in nematic liquid crystals. This significantly enhances the light absorption difference between the dark and bright states of the dimming film, solving the problem of low contrast in existing anthraquinone dyes.

[0034] 2. The anthraquinone dye skeleton selected in this invention possesses excellent photostability, overcoming the problem of easy fading of azo dyes. Simultaneously, the optimized molecular structure ensures its stability at high temperatures, solving the problem of high-temperature instability in high-concentration dye applications. Detailed Implementation

[0035] To make the objectives, technical means, and beneficial effects of this invention clearer, the technical content of this invention will be clearly and systematically described below in conjunction with several specific embodiments. It should be noted that many details are listed in the following description to facilitate a thorough understanding of this disclosure; however, the embodiments of this disclosure are not limited thereto. Obviously, the embodiments listed herein are only some examples and do not cover all possible implementation scenarios.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment involved in this invention can be obtained through market purchases or prepared by known conventional methods.

[0037] Unless otherwise specified, the preparation methods used in this invention shall be performed in accordance with conventional practices in the art; unless otherwise specified, all raw materials used are from commercially available sources; unless otherwise specified, all percentages refer to mass percentages; and the test conditions are set as follows: Determination of cleaning point: DSC quantitative analysis method was used; Optical anisotropy determination: Abbe refractometer was used, and the test conditions were 25±2℃ and 589nm wavelength. Dielectric anisotropy determination: An INSTEC:ALCT CUST 4C instrument was used, and the test conditions were 25±0.5℃, TN7.0-R mode; Color measurement: Spectrophotometer (model CM-36dG) was used. The performance parameters of the nematic liquid crystal XM1-001 used in this invention are: clearing point 119℃, optical anisotropy 0.234, and dielectric anisotropy 21.6.

[0038] The preparation process of the dye PDLC composition used in the embodiments or comparative examples of the present invention includes the following steps: 1. Weigh each component of the UV-curable adhesive (UVA) according to Table 1, and stir at room temperature until completely dissolved and mixed evenly; 2. Weigh each component of the dichroic dye liquid crystal according to Tables 2, 4, 5 and 6, and stir evenly under heating at 90°C; 3. The spacers used in this experiment were made of black polymethyl methacrylate material with a particle size of 20 μm.

[0039] 4. Mix the above-mentioned photocurable adhesive, dichroic dye liquid crystal and spacer, and stir evenly to obtain the desired dye PDLC composition.

[0040] The preparation method of the PDLC dimming film of the present invention is as follows: 1. Prepare two layers of transparent conductive film with the following parameters: transmittance 88%, sheet resistance 120 Ω, and thickness 188 μm.

[0041] 2. After accurately measuring the obtained dye PDLC composition, uniformly drop (or dispense) it onto the conductive layer surface of one of the transparent conductive films.

[0042] 3. Using a roll-to-roll production method, another transparent conductive film is precisely aligned and bonded to the substrate on which the composition is applied using a molding machine (or laminator / bonding device).

[0043] 4. During the bonding process, the PDLC composition is uniformly dispersed between the two thin films to form a liquid crystal-polymer prepolymer layer with a specific thickness (controlled by spacers), thereby obtaining the test sample.

[0044] 5. The bonded samples are then cured under ultraviolet light. During the curing process, the ultraviolet light intensity is set to 50 J / cm². 2 Ultimately, a stable polymer-dispersed liquid crystal, i.e., a dye PDLC sample, is formed.

[0045] The synthesis method of the dichroic dye monomer used in the embodiments of the present invention is as follows: The dye monomers used in this invention are all based on anthraquinone compounds as the parent compound, and are prepared by introducing different types of substituents into the active sites of the anthraquinone molecule. Depending on the type of substituent introduced, the preparation methods of the dye monomers mainly include the following three reaction pathways: 1. Alkoxylation of hydroxyanthraquinones yields alkoxylated anthraquinone dye monomers; 2. Nucleophilic substitution or coupling reactions of haloanthraquinones with amine compounds yield amino-substituted anthraquinone dye monomers; 3. The nucleophilic aromatic substitution reaction of haloanthraquinones with thiols or alcohols yields anthraquinone dye monomers with thioether or ether bonds.

[0046] All of the above reactions can be carried out under conventional equipment and conditions in this field, and the resulting products have well-defined structures, good reproducibility, and are suitable for large-scale preparation.

[0047] The following detailed explanation uses preparation examples 1-3 as examples: Preparation Example 1: Synthesis of hydroxy / alkoxyanthraquinone monomers (using Formula I-5 as an example) Step 1: Preparation of intermediate 4-(trans-4-propylcyclohexyl)benzyl bromide: In a 500 mL three-necked flask equipped with a mechanical stirrer, reflux condenser, and drying tube, 23.2 g (0.1 mol) of 4-(trans-4-propylcyclohexyl)benzyl alcohol and 250 mL of dry dichloromethane were added. Under ice-water bath cooling (0-5 °C), a 50 mL solution of phosphorus tribromide (13.5 g, 0.05 mol) in dichloromethane was slowly added dropwise, controlling the dropping rate to keep the reaction solution temperature below 10 °C. After the addition was complete, the ice bath was removed, and the mixture was allowed to warm naturally to room temperature with stirring for 4 hours. After the reaction was complete, the reaction solution was slowly poured into 500 mL of ice water to quench the reaction, and the organic phase was collected by separation. The aqueous phase was extracted with dichloromethane (2 × 100 mL). The combined organic phases were washed successively with saturated sodium bicarbonate aqueous solution and saturated brine, and dried over anhydrous magnesium sulfate. The solvent was removed by filtration and rotary evaporation under reduced pressure. The resulting white solid was recrystallized from n-hexane to give the intermediate 4-(trans-4-propylcyclohexyl)benzyl bromide.

[0048] Step 2: In a 250 mL three-necked flask equipped with a mechanical stirrer, nitrogen protection port, and condenser, add 1,5-diamino-4,8-dihydroxy-9,10-anthraquinone (2.70 g, 10 mmol), anhydrous N,N-dimethylformamide (DMF) (60 mL), and... Anhydrous potassium carbonate (K₂CO₃) (1.66 g, 12 mmol) was added and heated to 60 °C under nitrogen protection, maintaining this temperature and stirring for 30 minutes until a dark purple suspension was formed. Then, 4-(trans-4-propylcyclohexyl)benzyl bromide (3.54 g, 12 mmol) obtained in step 1 was dissolved in 15 mL of DMF and slowly added dropwise to the above reaction solution using a constant-pressure dropping funnel over approximately 30 minutes. After the addition was complete, the temperature was raised to 95 °C and maintained at this temperature for 8 hours. The reaction progress was monitored by thin-layer chromatography (TLC) (developing solvent: toluene / ethyl acetate = 5:1) until the starting material spot essentially disappeared and the amount of disubstituted byproducts was low, at which point the reaction was stopped.

[0049] Post-treatment and purification: The reaction mixture was cooled to room temperature and slowly poured into 500 mL of dilute hydrochloric acid aqueous solution (1 mol / L). The mixture was stirred vigorously for 1 hour, resulting in the precipitation of a deep blue precipitate. The precipitate was filtered, and the filter cake was washed with a large amount of deionized water until the filtrate was neutral. The filtrate was then dried in a vacuum drying oven at 60 °C for 12 hours. The crude product was purified by silica gel column chromatography using toluene:ethyl acetate (v / v 10:1) as the eluent. The main color band was collected, the solvent was removed by rotary evaporation, and the product was recrystallized in acetone. After vacuum drying, the target dye monomer was obtained.

[0050] Preparation Example 2 (Amino-substituted dyes, taking Formula I-3 as an example) This synthetic example uses 1,5-dihydroxy-4,8-dinitroanthraquinone as the starting material. After undergoing a monosubstitution reaction with an amine compound, the remaining nitro group is reduced to obtain the target product.

[0051] Step 1: Preparation of intermediate: 1,5-dihydroxy-4-nitro-8-[((trans)-4-isopropylcyclohexyl)methyl]aminoanthraquinone: In a 500 mL four-necked flask equipped with a mechanical stirrer, thermometer, and reflux condenser, 33.0 g (0.10 mol) of 1,5-dihydroxy-4,8-dinitroanthraquinone and 200 mL of N-methylpyrrolidone (NMP) were added. Stirring was started, and the mixture was heated to 50°C. Subsequently, a solution of NMP (50 mL) containing 17.1 g (0.11 mol) of ((trans)-4-isopropylcyclohexyl)methylamine and 11.0 g of triethylamine was slowly added dropwise over 30 minutes. The temperature was controlled to not exceed 60°C during the addition. After the addition was complete, the temperature was raised to 80°C and the reaction was carried out for 4 hours.

[0052] The reaction process was monitored by thin-layer chromatography (TLC) (developing solvent: toluene / ethyl acetate = 5:1). Heating was stopped once the starting spot had largely disappeared and the main spot no longer changed. The mixture was cooled to room temperature, poured into 1000 mL of ice water, and stirred vigorously to precipitate. The precipitate was filtered, washed with water until neutral, and dried under vacuum to give approximately 40 g of a dark red solid intermediate. This intermediate could be used directly in the next reaction without further purification.

[0053] Step 2: Preparation and purification of the target product (I-3): The dried intermediate solid was added to a 1000 mL reaction flask, along with 300 mL of water and 150 mL of ethanol, and stirred to suspend. Then, 48.0 g (0.20 mol) of sodium sulfide nonahydrate was added. The mixture was slowly heated to 90-95 °C and refluxed for 3 hours. During the reaction, the system color gradually changed from dark red to deep blue. TLC monitoring showed that the intermediate nitro compound spots disappeared, and new blue product spots were generated.

[0054] After the reaction was complete, the mixture was cooled to room temperature. The pH was adjusted to neutral with dilute hydrochloric acid, and the crude product was collected by filtration. The filter cake was thoroughly washed with water to remove inorganic salts and dried to obtain the target dye monomer.

[0055] Preparation Example 3 (Thioether / ether-substituted dyes, taking II-5 as an example) This synthetic example uses 1,5-dichloro-2,3-dimethylanthraquinone as the starting material, which undergoes a nucleophilic substitution reaction with 4-propylbenzylamine under alkaline conditions and copper salt catalysis to obtain the target compound 1,5-bis((4-propylbenzyl)amino)-2,3-dimethylanthraquinone.

[0056] In a 500 mL four-necked flask equipped with a mechanical stirrer, reflux condenser, thermometer, and nitrogen protection port, the following were added sequentially: starting material: 1,5-dichloro-2,3-dimethylanthraquinone: 30.5 g (0.10 mol); solvent: N-methylpyrrolidone (NMP): 250 mL; inorganic base: anhydrous potassium carbonate: 27.6 g (0.20 mol); catalyst: cuprous iodide (CuI): 0.57 g (3 mmol). Stirring was started, and high-purity nitrogen was purged into the reaction flask to purge the air for approximately 15 minutes. Subsequently, the following amine reactant: 4-propylbenzylamine: 37.3 g (0.25 mol) was added in one go with stirring. Under nitrogen protection, the reaction system was slowly heated to 150 ± 5 °C and maintained at this temperature with stirring for 12 hours.

[0057] Reaction monitoring: Samples were taken for thin-layer chromatography (TLC) detection (developing solvent: toluene / ethyl acetate = 10:1). The reaction endpoint was determined when the starting material spot completely disappeared and the reaction solution completely changed from yellowish-brown to deep purple-red.

[0058] After the reaction is complete, stop heating and allow the reaction solution to cool naturally to approximately 60 °C. While stirring vigorously, slowly pour the reaction solution into a 1000 mL methanol / water (volume ratio 1:1) mixture. A large amount of purplish-red solid will precipitate at this point. Continue stirring for 1 hour to allow the crystals to age fully.

[0059] The precipitated solid was collected by vacuum filtration. The filter cake was then washed sequentially as follows: with 200 mL of 50% methanol aqueous solution; with 500 mL of warm water until the filtrate was neutral and free of chloride ions (as detected by silver nitrate); and rinsed with a small amount of cold anhydrous ethanol. The filter cake was then placed in a vacuum drying oven and dried at 80 °C to constant weight to obtain the target dye monomer.

[0060] For dye monomers with multiple substituents or complex substituent structures, each substituent can be introduced step by step through a multi-step reaction. Each reaction step can be used alone or in combination, and the order of the steps is not restricted.

[0061] The functional side chains in the substituents can be synthesized in advance using methods known in the art, and participate in nucleophilic substitution, coupling, or etherification reactions in their integral structural form to introduce anthraquinone nuclei. During the multi-step reaction process, the introduction of each substituent does not substantially adversely affect the structure and properties of the introduced substituents, and those skilled in the art can rationally select the reaction sequence and conditions according to the target structure. When the target dye monomer contains multiple reactive sites, the desired substitution structure can be achieved through selective activation, stoichiometric control, or stepwise reactions. Therefore, the synthetic method described in this application can cover all dye monomer structures shown in Formulas I, II, III, IV, and V.

[0062] Examples 1-6 and Comparative Examples 1-4 of this invention each provide a BDLC dimming film, all prepared according to the methods described above. The photocurable adhesive used is shown in Table 1; the composition of the dichroic dye liquid crystal used in Examples 1-6 is shown in Table 2; the components of the dimming films in Examples 1-6 and their corresponding percentage content are shown in Table 3; the composition of the dichroic dye liquid crystal used in Comparative Examples 1-4 is shown sequentially in Tables 4-7; and the components of the dimming films in Comparative Examples 1-4 and their corresponding percentage content are shown in Table 8. Here, "XM1-001" represents a nematic liquid crystal.

[0063] Table 1 UV-curable adhesives

[0064] Table 2. Composition and percentage content of dichroic dye liquid crystals (DLCs) 1-6 used in Examples 1-6

[0065] Table 3. Components and corresponding percentages of dimming films in Examples 1-6

[0066] In Table 3, the percentage content of spacers represents their mass percentage in the total mass of the photocurable adhesive and the dichroic dye liquid crystal.

[0067] Table 4. Composition and percentage content of the dye liquid crystal used in Comparative Example 1

[0068] Table 5. Composition and percentage content of the dye liquid crystal used in Comparative Example 2

[0069] Table 6. Composition and percentage content of the dye liquid crystal used in Comparative Example 3

[0070] Table 7. Composition and percentage content of the dye liquid crystal used in Comparative Example 4

[0071] Table 8. Components and corresponding percentage content of dimming films in Comparative Examples 1-4

[0072] In Table 8, the percentage content of spacers represents their mass percentage in the total mass of the photocurable adhesive and the dichroic dye liquid crystal.

[0073] Application examples The photoelectric performance of the PDLC dimming films obtained in Examples 1-6 and Comparative Examples 1-4 were tested respectively. The test methods were as follows: The dye PDLC dimming films prepared in each embodiment and comparative example were subjected to an AC current of 48V. The haze and transmittance of the PDLC dimming films in the dark state (0V without power) and the transparent state (48V with power) were tested using a color spectrometer TH-110. The contrast ratio of the PDLC dimming film (transparent state transmittance / dark state transmittance) was calculated. The test results are shown in Table 9 below.

[0074] Table 9. Haze, transmittance, contrast ratio, and appearance of dye-based PDLC dimming films

[0075] Color difference analysis was performed on the PDLC dimming films prepared in Examples 1-6 and Comparative Examples 1-4, respectively. The initial L*, a*, and b* values ​​of the samples were measured and recorded as L0*, a0*, and b0*. After 1000 hours of xenon lamp aging, the L*, a*, and b* values ​​of the samples were measured again and recorded as L1*, a1*, and b1*. The values ​​of ΔL*, Δa*, and Δb* were further calculated, where: ΔL*=L0*-L1*; Δa*=a0*-a1*; Δb*=b0*-b1*; Calculate the total color difference value ΔE using the following formula: ΔE=[(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 ] 1 / 2 , The data results are shown in Table 10.

[0076] Table 10 Lab values ​​and color differences of dye PDLC before and after xenon lamp aging

[0077] As shown in Table 9, the contrast ratios of the dimming films in Examples 1-6 of this invention are all between 20.21 and 21.73, and the 0V transmittance is relatively low, indicating that the novel anthraquinone dye of this invention has a high degree of orientation, achieving high contrast and excellent dark-state shading effect. Comparative Example 2 (an existing anthraquinone dye) has a contrast ratio of only 6.3 and a relatively high 0V transmittance, indicating the deficiency of insufficient contrast in existing anthraquinone dyes. The contrast ratio of Comparative Example 3 is also low, at only 8.26. Furthermore, Comparative Example 2 exhibits "dye precipitation" in appearance, while Examples 1-6 of this invention all appear normal, proving that the novel anthraquinone dye of this invention has excellent solubility and formulation stability. Although Comparative Example 4 shows some improvement in solubility and contrast compared to Comparative Example 2, Examples 1-6 of this invention still have significantly better contrast ratios than Comparative Example 4 while maintaining equivalent solubility, demonstrating that the design of this invention has a significant effect on improving dye contrast.

[0078] As shown in Table 10, the ΔE values ​​of Examples 1-6 of the present invention are all in the range of 0.13 to 0.83, with the ΔE of Example 1 being only 0.13, indicating that the novel anthraquinone dye of the present invention has excellent photostability and minimal color change after long-term aging. The azo dye of Comparative Example 1 has a higher ΔE, reaching 8.13, and its L value increased from 16.4 to 23.42 after aging, indicating that the azo dye suffers from severe photofading defects. The mixed dye of Comparative Example 3 also has a high ΔE, reaching 4.49, indicating that its stability is still affected by the azo component and is far inferior to that of the present invention.

[0079] In summary, the dye PDLC dimming film prepared in the embodiments of the present invention exhibits significant advantages in two key dimensions: photoelectric performance and environmental stability. In particular, it has made significant progress in overcoming the two major technical challenges of low contrast of existing anthraquinone dyes and easy fading of azo dyes.

[0080] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-contrast anthraquinone dye PDLC composition, characterized in that, include: Dichroic dye liquid crystals, photocurable adhesives, and spacers; The dichroic dye liquid crystal comprises a nematic liquid crystal and a dichroic dye; the dichroic dye comprises at least one compound selected from the following formulas I, II, III, IV or V: Formula I, Formula II, Formula III, Formula IV, Formula V, to Each represents independently , , , , , or ; X1, X3, X4, X5, X8, X 11 X 12 X 15 Each can independently represent -H, -NH2, -NHCH3, -NHC4H9, -NAr, -OH, or a halogen; X2, X6, X7, X9, X 10 X 13 X 14 X 16 -X 20 Each can be independently represented as -OCH2-, -NHCH2-, -OCF2-, -SCH2-, or -OCO-; R1-R4, R6-R9, R 12 -R 15 R 18 -R 21 R 25 -R 28 Each can independently represent -H, -CH3, halogen, or one of the following groups: 、 、 、 ； R5, R 10 R 11 R 16 R 17 R 22 -R 24 R 29 -R 32 Each can independently represent -H, a straight-chain or branched alkyl group with 1 to 12 carbon atoms, an alkoxy group, an alkyl carbonyl group, or an alkoxy carbonyl group; Z1-Z 12 Each can independently represent a single bond, a methylene group, or -OCO-; each 'al' independently represents 0 or 1.

2. The high-contrast anthraquinone dye PDLC composition according to claim 1, characterized in that, In formulas I, II, III, IV, or V: to Each represents independently or ; X1, X3, X4, X5, X8, X 11 X 12 X 15 Each can independently represent -H, -NH2, or -OH; X2, X6, X7, X9, X 10 X 13 X 14 X 16 -X 20 Each can be independently represented as -OCH2-, -NHCH2-, or -SCH2-; R1-R4, R6-R9, R 12 -R 15 R 18 -R 21 R 25 -R 28 Each can be independently represented as -H or -CH3; R5, R 10 R 11 R 16 R 17 R 22 -R 24 R 29 -R 32 Each can independently represent a straight-chain or branched alkyl group with -H and 1 to 12 carbon atoms; Z1-Z 12 Indicates a single key; each 'al' independently represents 0 or 1.

3. The high-contrast anthraquinone dye PDLC composition according to claim 2, characterized in that, The compound represented by Formula I is selected from any one or more of the compounds shown in Formulas I-1 to I-8: The compound represented by Formula II is selected from any one or more of the compounds shown in Formulas II-1 to II-6: The compound represented by Formula III is selected from any one or two of the compounds shown in Formulas III-1 to III-2: The compound represented by Formula IV is selected from any one or two of the compounds represented by Formulas IV-1 to IV-2: The compound represented by Formula V is selected from any one or more of the compounds represented by Formulas V-1 to V-4: 。 4. The high-contrast anthraquinone dye PDLC composition according to claim 1, characterized in that, With the total mass of the dichroic dye liquid crystal and the photocurable adhesive being 100%, the mass ratio of the dichroic dye liquid crystal to the photocurable adhesive is 35~65:65~35, and the content of the spacer is 0.3-1.5% of the total mass of the dichroic dye liquid crystal and the photocurable adhesive. The dichroic dye liquid crystal comprises, by mass percentage, 1-10% of the dichroic dye and 90-99% of the nematic liquid crystal; wherein the clearing point of the nematic liquid crystal is ≥90℃, the optical anisotropy is >0.18, and the dielectric anisotropy is >5.

5. The high-contrast anthraquinone dye PDLC composition according to claim 1, characterized in that, The UV-curable adhesive, calculated by weight percentage, comprises: Polyurethane acrylate oligomers: 10-24 wt% Reactive diluent: 74.5-84.5 wt% Additives: 0.5-3 wt% Photoinitiator: 1-3 wt%.

6. The high-contrast anthraquinone dye PDLC composition according to claim 5, characterized in that, The polyurethane acrylate oligomers are selected from one or more of the following: aliphatic polyurethane acrylates, alicyclic polyurethane acrylates, aromatic polyurethane acrylates, polyester acrylates, polyether-modified acrylates, and epoxy acrylates; The reactive diluent is selected from one or more of the following: dodecyl acrylate, isodecyl acrylate, dicyclopentenyl acrylate, benzyl acrylate, isobornyl acrylate, o-phenylphenoxyethyl acrylate, 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, ethoxylated trimethylolpropane triacrylate, tetradecyl methacrylate, hydroxybutyl methacrylate, isobornyl methacrylate, hydroxypropyl methacrylate, acryloylmorpholine, N,N-dimethylacrylamide, and N-hydroxyethylacrylamide. The additives are selected from one or two of silane coupling agents and phosphate ester modifiers; The photoinitiator is selected from one or more of photoinitiator TPO, photoinitiator 819, photoinitiator 184, photoinitiator ITX, photoinitiator 907, photoinitiator TPO-L, photoinitiator 1173 and photoinitiator 784.

7. The high-contrast anthraquinone dye PDLC composition according to claim 1, characterized in that, The spacers are black or white microspheres with a particle size of 10-30 μm, and the microspheres are made of acrylic polymers, polystyrene or silica.

8. A dye-based PDLC dimming film, characterized in that, The dimming film comprises two conductive films and a dye PDLC layer disposed between the two conductive films, which is formed by UV curing of the high-contrast anthraquinone dye PDLC composition according to any one of claims 1-7.

9. The dye PDLC dimming film according to claim 8, characterized in that, The conductive film has a transmittance of 10-90%, a sheet resistance of 5-250Ω, and a thickness of 50-250μm.

10. The dye PDLC dimming film according to claim 8, characterized in that, The UV curing irradiation dose is 3-100 J / cm². 2 .

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