PDLC coating glue, its preparation method and application

Abstract

This application discloses a PDLC coating adhesive, its preparation method, and its application, relating to the field of liquid crystal dimming film technology. The PDLC coating adhesive comprises the following raw materials in parts by weight: 20-30 parts of acrylate oligomer, 30-60 parts of a first acrylate monomer, 15-40 parts of a second acrylate monomer, 0.5-2.0 parts of silane-modified nanoscale inorganic filler, 50-60 parts of nematic liquid crystal, 0.5-2.0 parts of photoinitiator, and 1.5-2.4 parts of carboxyl-containing additive. The PDLC coating adhesive provided in this application ensures the uniformity and stability of liquid crystal dispersion in the polymer system. After curing, it effectively promotes sufficient phase separation between liquid crystal microdroplets and the polymer network backbone, improving the haze change rate of the film and enhancing its voltage breakdown resistance.

Description

Technical Field

[0001] This application relates to the field of liquid crystal dimming film technology, and in particular to a PDLC coating adhesive, its preparation method and application. Background Technology

[0002] Liquid crystal dimming film, also known as dimming electronic curtain film or polymer-dispersed liquid crystal (PDLC) film, is manufactured by dispersing liquid crystals in micron-sized droplets within a polymer matrix between two transparent thin film materials using a special process. PDLC film is an important electrochromic material. When no electricity is applied, the liquid crystal droplets are randomly arranged, strongly scattering incident light, and the film is opaque. When electricity is applied, the liquid crystal molecules align under the influence of the electric field, allowing light to pass through, and the film becomes transparent. This technology is widely used in smart dimming glass, projection screens, and display devices.

[0003] To achieve good mechanical strength and optical properties, the thickness of existing PDLC layers is typically 15–30 micrometers. However, thicker films have the following drawbacks:

[0004] 1. Poor flexibility: The thicker film layer limits the bending radius of the entire dimming film, making it unsuitable for use on flexible devices.

[0005] Second, the required driving voltage is usually above 50VAC, which results in high driving voltage and high power consumption.

[0006] To improve flexibility and reduce driving voltage, the industry has attempted to thin the PDLC layer. However, when the PDLC layer is thinned to below 10 micrometers, especially around 6 micrometers, the following new problems arise:

[0007] (1) The ultrathin dielectric layer may form a high electric field strength at a low voltage, which is easily broken down by voltage, resulting in poor product reliability;

[0008] (2) The sharp reduction in thickness causes the phase separation behavior between the polymer network and the liquid crystal to change, making it difficult to form liquid crystal droplets of uniform size. It also affects the uniformity of the distribution of liquid crystal droplets, resulting in insufficient whiteness in the hazy state and insufficient transparency in the transparent state, and a significant reduction in the haze change rate. Summary of the Invention

[0009] The main purpose of this application is to propose a PDLC coating adhesive, its preparation method and application, aiming to solve the problems of existing ultra-thin PDLC layers being easily broken down by voltage and having a low haze change rate.

[0010] In a first aspect, this application provides a PDLC coating adhesive comprising the following raw materials in parts by weight: 20-30 parts of acrylate oligomer, 30-60 parts of a first acrylate monomer, 15-40 parts of a second acrylate monomer, 0.5-2.0 parts of silane-modified nanoscale inorganic filler, 50-60 parts of nematic liquid crystal, 0.5-2.0 parts of photoinitiator, and 1.5-2.4 parts of carboxyl-containing additive;

[0011] The acrylate oligomers include polycaprolactone-type polyurethane acrylate oligomers and polyether-type polyurethane acrylate oligomers, wherein the weight ratio of the polycaprolactone-type polyurethane acrylate oligomers to the polyether-type polyurethane acrylate oligomers is (2.5~3.5):1; the raw materials for preparing the polycaprolactone-type polyurethane acrylate oligomers include polycaprolactone diol, hexamethylene diisocyanate, and 4-hydroxybutyl acrylate; the raw materials for preparing the polyether-type polyurethane acrylate oligomers include tetrahydrofuran homopolymer ether, hexamethylene diisocyanate, and hydroxyethyl methacrylate.

[0012] The first acrylate monomer includes acrylate containing an alkyl chain, 1,3-propylene glycol diacrylate, and hydroxyethyl methacrylate;

[0013] The second acrylate monomer includes tetrahydrofuran acrylate, benzyl methacrylate, methyl 2-[(2-propen-1-yloxy)methyl]-2-acrylate and o-phenylphenoxyethyl acrylate.

[0014] By adopting the above technical solution, a polymer formed by combining specific polycaprolactone-type polyurethane acrylate oligomers and polyether-type polyurethane acrylate oligomers is used as the base material. This polymer is stably combined with the first acrylate monomer and the second acrylate monomer, ensuring the uniformity and stability of the liquid crystal dispersion in the polymer system. After curing, a network skeleton with suitable density and excellent toughness and elasticity can be formed, effectively promoting sufficient phase separation between the liquid crystal microdroplets and the polymer network skeleton. This allows the liquid crystal microdroplets to be dispersed in the network skeleton with a more uniform size, improving the haze change rate of the film and enhancing the voltage breakdown resistance.

[0015] A composite polymer of polycaprolactone-type polyurethane acrylate oligomers and polyether-type polyurethane acrylate oligomers is used as the matrix material and backbone. In the first acrylate monomer, the alkyl-chain acrylate reduces the polymer's rigidity and increases the flexibility of the polymer chain segments. Its long carbon chain structure interspersed between the polymer backbone weakens intermolecular forces, making the chain segments easier to rotate, effectively reducing the driving voltage of the PDLC layer and reducing energy consumption. Simultaneously, it also reduces haze under energized conditions, making the PDLC layer more transparent when energized. The addition of 1,3-propylene glycol diacrylate and hydroxyethyl methacrylate improves the polymer's rapid resilience, allowing the chain segments to quickly recover to their original configuration through intermolecular forces after the removal of external force or electric field, reducing chain segment entanglement and permanent deformation. The PDLC layer can more thoroughly return to its initial state after repeated on / off cycles, significantly weakening or even eliminating the hysteresis effect.

[0016] The addition of tetrahydrofuran acrylate to the second acrylate monomer effectively improves the dispersion uniformity and stability of the liquid crystal in the polymer system, prevents phase separation between the liquid crystal and the adhesive during construction, and reduces the construction difficulty in the manufacturing and bonding process; moreover, the same amount of PDLC coating adhesive can carry more liquid crystal. The addition of benzyl methacrylate, methyl 2-[(2-propen-1-yloxy)methyl]-2-acrylate and o-phenylphenoxyethyl acrylate can effectively improve the stability and refractive index matching of the network skeleton, and improve the haze change rate of the film.

[0017] The introduction of silane-modified nanoscale inorganic fillers, with nanoscale inorganic particles uniformly dispersed in the polymer network, effectively blocks, segments, and extends conductive pathways, significantly improving the dielectric strength and breakdown resistance of the PDLC layer. Furthermore, the nanoscale inorganic particles can also serve as nucleation sites for liquid crystal phase separation, synergistically promoting the formation of appropriately sized and uniformly distributed liquid crystal microdroplets during curing, thereby optimizing photoelectric properties.

[0018] Preferably, the weight ratio of polycaprolactone-type polyurethane acrylate oligomer to polyether-type polyurethane acrylate oligomer in the acrylate oligomer is 3:1.

[0019] Optionally, the preparation method of the polycaprolactone-type polyurethane acrylate oligomer includes the following steps: mixing polycaprolactone diol with hexamethylene diisocyanate, stirring, adding an organotin catalyst, controlling the temperature at 40~50℃, reacting for 1.5~2.5h, controlling the temperature at 50~60℃, adding 4-hydroxybutyl acrylate and hydroquinone, maintaining the temperature at 50~60℃, reacting for 1.5~2.5h, controlling the temperature at 65~70℃, reacting for 2~3h, to obtain the polycaprolactone-type polyurethane acrylate oligomer; wherein the mass ratio of polycaprolactone diol, hexamethylene diisocyanate and 4-hydroxybutyl acrylate is (400~550):(350~400):(280~290); and / or,

[0020] The method for preparing the polyether-type polyurethane acrylate oligomer includes the following steps: providing tetrahydrofuran homopolymer, adding an organotin catalyst, adding hexamethylene diisocyanate dropwise under dry air conditions, reacting at 55-60°C for 2-3 hours while controlling the temperature at 60-70°C, adding hydroxyethyl methacrylate dropwise, and simultaneously adding hydroquinone, controlling the temperature at 65-70°C, and reacting for 2-3 hours to obtain the polyether-type polyurethane acrylate oligomer; wherein the mass ratio of tetrahydrofuran homopolymer, hexamethylene diisocyanate, and hydroxyethyl methacrylate is 98:(53-55):(45-47).

[0021] Preferably, the mass ratio of polycaprolactone diol, hexamethylene diisocyanate, and 4-hydroxybutyl acrylate is 530:353.2:288.4.

[0022] Preferably, the mass ratio of tetrahydrofuran homopolymer ether, hexamethylene diisocyanate, and hydroxyethyl methacrylate is 98:54.2:46.2.

[0023] By adopting the above technical solution, a polymer formed by combining specific polycaprolactone-type polyurethane acrylate oligomers and polyether-type polyurethane acrylate oligomers is used as the base material and skeleton. This polymer is stably combined with the first acrylate monomer and the second acrylate monomer, ensuring the uniformity of liquid crystal dispersion in the polymer system. After curing, a network skeleton with suitable density and excellent toughness and elasticity can be formed, effectively promoting sufficient phase separation between liquid crystal droplets and polymer network skeleton. This allows the liquid crystal droplets to be dispersed in the network skeleton with a more uniform size, improving the haze change rate of the film and enhancing the voltage breakdown resistance.

[0024] Optionally, the weight ratio of the acrylate oligomer to the first acrylate monomer is (0.5~0.7):1.

[0025] Preferably, the weight ratio of the acrylate oligomer to the first acrylate monomer is 0.6:1.

[0026] By adopting the above technical solution and further optimizing the ratio of acrylate oligomers to the first acrylate monomer, a polymer network skeleton with more suitable density and excellent toughness and elasticity can be formed.

[0027] Optionally, in the first acrylate monomer, the acrylate containing an alkyl chain is tridecyl acrylate, and the weight ratio of the acrylate containing an alkyl chain, 1,3-propylene glycol diacrylate and hydroxyethyl methacrylate is (1.8~2.2):1:1.

[0028] Preferably, in the first acrylate monomer, the acrylate containing an alkyl chain is tridecyl acrylate, and the weight ratio of the acrylate containing an alkyl chain, 1,3-propylene glycol diacrylate, and hydroxyethyl methacrylate is 2:1:1.

[0029] By adopting the above technical solution, the composition ratio of the first acrylate monomer is controlled to further improve the mechanical properties of the formed polymer network skeleton.

[0030] Optionally, the raw materials for preparing the silane-modified nanoscale inorganic filler include nanoscale silica and silane coupling agent, and the weight ratio of the second acrylate monomer to the silane-modified nanoscale inorganic filler is 25:1.

[0031] By adopting the above technical solution and further optimizing the ratio of the second acrylate monomer and the silane-modified nanoscale inorganic filler, liquid crystal microdroplets of suitable size and more uniform distribution can be formed, thereby further improving the photoelectric properties of the film.

[0032] Optionally, in the second acrylate monomer, the weight ratio of tetrahydrofuran acrylate, benzyl methacrylate, methyl 2-[(2-propen-1-yloxy)methyl]-2-acrylate and o-phenylphenoxyethyl acrylate is 1:(0.5~0.7):(1.4~1.6):1.

[0033] Preferably, in the second acrylate monomer, the weight ratio of tetrahydrofuran acrylate, benzyl methacrylate, methyl 2-[(2-propen-1-yloxy)methyl]-2-acrylate and o-phenylphenoxyethyl acrylate is 1:0.6:1.5:1.

[0034] By adopting the above technical solution, the composition ratio of the second acrylate is controlled to further improve the dispersion uniformity of liquid crystal microdroplets.

[0035] Secondly, this application provides a method for preparing a PDLC coating adhesive as described in any of the above claims, comprising the following steps:

[0036] S1. Under light-protected conditions, mix the acrylate oligomer, the first acrylate monomer, the second acrylate monomer, the silane-modified nano-sized inorganic filler, the photoinitiator, and the carboxyl-containing auxiliary agent, and stir at a stirring rate of 300-500 rpm for 30-60 min. Under vacuum conditions, stir at a stirring rate of 2000-2500 rpm for 6-10 min to obtain component A.

[0037] S2. Place the nematic liquid crystal in an environment of 20~23℃ and let it stand for 30~90 min to obtain component B;

[0038] S3. Place component A obtained in step S1 in a light-proof environment at a temperature of 20~23℃, stir component A at a stirring rate of 200~400rpm, add component B obtained in step S2 to component A, and continue stirring for 60~120min to obtain the PDLC coating adhesive.

[0039] Thirdly, this application provides a method for preparing an electrochromic color-changing film using PDLC coating adhesive as described in any of the above claims, comprising the following steps:

[0040] (1) In an environment with a temperature of 20~23℃, the spacer is added to the PDLC coating adhesive and stirred to obtain the pre-coated adhesive, wherein the weight ratio of the spacer to the PDLC coating adhesive is (0.1~0.4):100;

[0041] (2) Provide two transparent conductive films distributed vertically, and uniformly apply the pre-coated adhesive obtained in step (1) onto the lower transparent conductive film, and cover the upper transparent conductive film onto the pre-coated adhesive to form a wet film between the two transparent conductive films.

[0042] (3) The wet film obtained in step (2) is pressed and cured with ultraviolet light to obtain an electrochromic color-changing film. The wet film is formed into a PDLC layer with a thickness of 6±0.5μm. The ultraviolet curing conditions are: ultraviolet light intensity of 12~15mW / cm². 2 The curing time is 2-4 minutes.

[0043] Preferably, in step (1), the weight ratio of the spacer to the PDLC coating adhesive is 0.2:100.

[0044] By adopting the above technical solution, the electrochromic color-changing film obtained has a lower driving voltage, lower energy consumption, higher clarity, higher haze change rate, and excellent voltage breakdown resistance.

[0045] Fourthly, this application provides an electrochromic color-changing film prepared by the method described above.

[0046] Fifthly, this application also provides an application of the electrochromic color-changing film as described above in smart windows, flexible display devices, or optical modulation devices.

[0047] In summary, this application includes at least one of the following beneficial technical effects:

[0048] 1. In the technical solution of this application, a specific polycaprolactone-type polyurethane acrylate oligomer and a polyether-type polyurethane acrylate oligomer are used as the base material. The polymer formed by the compounding of the two is used to stably cooperate with the first acrylate monomer and the second acrylate monomer, which ensures the uniformity of liquid crystal dispersion in the polymer system. After curing, a network skeleton with suitable density and excellent toughness and elasticity can be formed, which effectively promotes sufficient phase separation between liquid crystal microdroplets and polymer network skeleton, and causes liquid crystal microdroplets to be dispersed in the network skeleton with a more uniform size and more uniformly, thereby improving the haze change rate of the film and improving the voltage breakdown resistance.

[0049] 2. In the first acrylate monomer, acrylates containing alkyl chains can reduce the rigidity of the polymer and improve the flexibility of the polymer chain segments. Their long carbon chain structures interspersed between the polymer backbone weaken intermolecular forces, making the chain segments easier to rotate, effectively reducing the driving voltage of the PDLC layer and reducing energy consumption. Simultaneously, they can reduce haze under energized conditions, making the PDLC layer more transparent when energized. The addition of 1,3-propylene glycol diacrylate and hydroxyethyl methacrylate improves the polymer's rapid resilience, allowing the chain segments to quickly recover to their original configuration through intermolecular forces after the removal of external force or electric field, reducing chain segment entanglement and permanent deformation. The PDLC layer can more thoroughly return to its initial state after repeated on / off cycles, significantly weakening or even eliminating the hysteresis effect.

[0050] 3. The addition of tetrahydrofuran acrylate to the second acrylate monomer effectively improves the dispersion uniformity and stability of the liquid crystal in the polymer system, prevents phase separation between the liquid crystal and the adhesive during construction, and reduces the construction difficulty in the manufacturing and bonding process; moreover, the same amount of PDLC coating adhesive can carry more liquid crystal. The addition of benzyl methacrylate, methyl 2-[(2-propen-1-yloxy)methyl]-2-acrylate, and o-phenylphenoxyethyl acrylate can effectively improve the stability and refractive index matching of the network skeleton, and improve the haze change rate of the film.

[0051] 4. The introduction of silane-modified nanoscale inorganic fillers, with nanoscale inorganic particles uniformly dispersed in the polymer network, effectively blocks, segments, and extends conductive pathways, significantly improving the dielectric strength and breakdown resistance of the PDLC layer. Furthermore, the nanoscale inorganic particles can also serve as nucleation sites for liquid crystal phase separation, synergistically promoting the formation of appropriately sized and uniformly distributed liquid crystal microdroplets during curing, thereby optimizing photoelectric properties. Detailed Implementation

[0052] The present application will be further described in detail below with reference to embodiments. All raw materials involved in this application are commercially available, wherein...

[0053] Nematic liquid crystal: Yantai Xianhua Technology Group Co., Ltd., with a clearing point of 135.5℃, dielectric anisotropy ∆ε (20℃, 1kHz) of 11.3, and optical anisotropy ∆n (25℃, 589nm) of 0.248;

[0054] Transparent conductive film: including a PET base film and an ITO film disposed on the PET base film. The PET base film has a thickness of 125μm, a total light transmittance of 90%, and a haze of 0.3%. The ITO film has a thickness of 50nm and a sheet resistance of 50Ω.

[0055] Spacer: Plastic microparticles, trade name SP-206, from Dongguan Binku New Materials Co., Ltd., with an average particle size of 6.00±0.05μm;

[0056] Photoinitiator: 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyloxime);

[0057] Carboxyl-containing auxiliaries: mono[2-[(2-methyl-acryloyl)oxy]ethyl] succinate;

[0058] Polycaprolactone diol: Jiangshan Chemical (Shanghai) Co., Ltd., product name PLACEL 205;

[0059] Tetrahydrofuran homopolymer ether, Mitsubishi Chemical (China) Management Co., Ltd., grade PTMG 850;

[0060] Nano-silica, Kramar, particle size 7-40nm, specific surface area 300-350m² 2 / g.

[0061] Preparation Examples 1-6 provide methods for preparing PDLC coating adhesives. The specific raw materials are shown in Table 1 below, and the specific preparation methods include the following steps:

[0062] S1. Under light-protected conditions, the acrylate oligomer, the first acrylate monomer, the second acrylate monomer, the silane-modified nano-sized inorganic filler, the photoinitiator and the carboxyl-containing auxiliary agent are mixed and stirred at a stirring rate of 400 rpm for 45 min. Under vacuum conditions, the mixture is stirred at a stirring rate of 2200 rpm for 8 min to obtain a uniform and bubble-free component A.

[0063] S2. Place the nematic liquid crystal at 22°C and let it stand for 60 minutes to obtain component B.

[0064] S3. Place component A obtained in step S1 in a light-proof environment at a temperature of 22°C, stir component A at a stirring rate of 300 rpm, add component B obtained in step S2 to component A at a feeding rate of 50 g / min, and continue stirring at a stirring rate of 300 rpm for 100 min to obtain PDLC coating adhesive.

[0065] In step S1, the acrylate oligomer is obtained by mixing polycaprolactone-type polyurethane acrylate oligomer and polyether-type polyurethane acrylate oligomer in a weight ratio of 3:1.

[0066] A method for preparing polycaprolactone-type polyurethane acrylate oligomers includes the following steps: mixing polycaprolactone diol with hexamethylene diisocyanate, stirring at 200 rpm for 30 min to obtain a mixture, stirring at 200 rpm, adding dibutyltin dilaurate, controlling the temperature at 45℃, reacting for 2 h, controlling the temperature at 55℃, adding 4-hydroxybutyl acrylate and hydroquinone, maintaining the temperature at 55℃, reacting for 2 h, controlling the temperature at 70℃, reacting for 2 h, to obtain polycaprolactone-type polyurethane acrylate oligomers; wherein the mass ratio of polycaprolactone diol, hexamethylene diisocyanate, dibutyltin dilaurate, 4-hydroxybutyl acrylate and hydroquinone is 530:353.2:8.8:288.4:1.2.

[0067] A method for preparing polyether-type polyurethane acrylate oligomers includes the following steps: providing tetrahydrofuran homopolymer, adding dibutyltin dilaurate, stirring at 200 rpm for 30 min, stirring at 200 rpm under dry air conditions, adding hexamethylene diisocyanate dropwise, reacting at 55°C for 2 h, controlling the temperature at 65°C, adding hydroxyethyl methacrylate dropwise, and simultaneously adding hydroquinone, controlling the temperature at 70°C, and reacting for 2 h to obtain polyether-type polyurethane acrylate oligomers; wherein the mass ratio of tetrahydrofuran homopolymer, dibutyltin dilaurate, hexamethylene diisocyanate, hydroxyethyl methacrylate, and hydroquinone is 98:0.8:54.2:46.2:0.7.

[0068] The first acrylate monomer is obtained by mixing tridecyl acrylate, 1,3-propylene glycol diacrylate and hydroxyethyl methacrylate in a weight ratio of 2:1:1.

[0069] The second acrylate monomer is obtained by mixing tetrahydrofuran acrylate, benzyl methacrylate, methyl 2-[(2-propen-1-yloxy)methyl]-2-acrylate and o-phenylphenoxyethyl acrylate in a weight ratio of 1:0.6:1.5:1.

[0070] The preparation method of silane-modified nanoscale inorganic filler includes the following steps:

[0071] A1. Dry the nano-silica at 120℃ for 12h, mix the dried nano-silica with anhydrous ethanol at a mass ratio of 5:100, disperse by ultrasonication for 15min, centrifuge at 10000rpm for 30min, discard the supernatant, and obtain the pretreated silica dispersion.

[0072] A2. Methacryloxypropyltrimethoxysilane, anhydrous ethanol, and deionized water were prepared in a mass ratio of 2:7:1. The anhydrous ethanol and deionized water were mixed and stirred at 200 rpm for 10 min. Under the stirring condition of 200 rpm, methacryloxypropyltrimethoxysilane was added dropwise. The mixture was stirred at 30℃ and 200 rpm for 30 min. The pH value was adjusted to 4.5 with 1 wt% acetic acid aqueous solution and allowed to stand for 24 h to obtain the silane modified solution.

[0073] A3. The pretreated silica dispersion was heated to 65°C and stirred at 200 rpm under nitrogen protection. Silane modification solution was added dropwise, and the reaction was continued for 5 hours. The mixture was then naturally cooled to room temperature (25°C) and centrifuged at 10,000 rpm for 30 minutes to obtain modified silica. The silica was washed three times with anhydrous ethanol, and the resulting solid was dried under vacuum at 40°C for 12 hours to obtain silane-modified nanoscale inorganic filler.

[0074] In step A3, the mass ratio of the pretreated silica dispersion to the silane modified liquid is 1:3.3.

[0075] Table 1. Raw materials and dosage of PDLC coating adhesive (unit: g)

[0076]

[0077] Preparation Examples 7 and 8 are based on Preparation Example 3, except that the total mass of the second acrylate monomer and the silane-modified nano-sized inorganic filler remains constant at 260 g, while the ratio of their amounts is adjusted. All other steps are the same as in Preparation Example 3. Specifically,

[0078] In Preparation Example 7, the amount of the second acrylate monomer used was 245g, and the amount of silane-modified nanoscale inorganic filler used was 15g.

[0079] In Preparation Example 8, the amount of the second acrylate monomer used was 255g, and the amount of silane-modified nanoscale inorganic filler used was 5g.

[0080] Preparation of Comparative Example 1

[0081] This comparative example is based on Preparation Example 1, except that the acrylate oligomer in this comparative example is a polyether-type polyurethane acrylate oligomer, and the other steps are the same as in Preparation Example 1.

[0082] Preparation of Comparative Example 2

[0083] This comparative example is based on Preparation Example 1, except that the acrylate oligomer in this preparation example is a polycaprolactone-type polyurethane acrylate oligomer, and the other steps are the same as in Preparation Example 1.

[0084] Preparation of Comparative Example 3

[0085] This comparative example is based on Preparation Example 1, except that an equal weight of the second acrylate monomer is used to replace the first acrylate monomer, while the other steps are the same as in Preparation Example 1.

[0086] Preparation of Comparative Example 4

[0087] This comparative example is based on Preparation Example 1, except that an equal weight of the first acrylate monomer is used to replace the second acrylate monomer, while the other steps remain the same as in Preparation Example 1.

[0088] Preparation of Comparative Example 5

[0089] This comparative example is based on Preparation Example 1, except that the amount of silane-modified nanoscale inorganic filler used is 3.5 g, while the other steps are the same as in Preparation Example 1.

[0090] Example 1: A method for preparing an electrochromic color-changing film using PDLC coating adhesive, comprising the following steps:

[0091] (1) In an environment with a temperature of 22°C, the spacer was added to the PDLC coating adhesive prepared in Preparation Example 1 and stirred at a stirring rate of 200 rpm for 120 min to obtain the pre-coated adhesive, wherein the weight ratio of the spacer to the PDLC coating adhesive was 0.2:100.

[0092] (2) Provide two transparent conductive films distributed vertically. Apply the pre-coated adhesive obtained in step (1) evenly to the conductive surface of the lower transparent conductive film and cover the conductive surface of the upper transparent conductive film with the pre-coated adhesive to form a wet film between the two transparent conductive films.

[0093] (3) The wet film obtained in step (2) is pressed and cured with ultraviolet light to obtain an electrochromic color-changing film. The wet film is formed into a PDLC layer. The ultraviolet curing conditions are: curing temperature of 25℃ and ultraviolet light intensity of 13mW / cm. 2 The curing time is 3 minutes.

[0094] The thickness of the PDLC layer was measured to be 6±0.5μm.

[0095] Examples 2-8 are based on Example 1, the difference being that the source of the PDLC coating adhesive is different in step (1), while the other steps remain the same as in Example 1. Specifically,

[0096] In Example 2, the PDLC coating adhesive prepared in Preparation Example 2 was used; the thickness of the resulting PDLC layer was measured to be 6 ± 0.5 μm.

[0097] In Example 3, the PDLC coating adhesive prepared in Preparation Example 3 was used; the thickness of the resulting PDLC layer was measured to be 6 ± 0.5 μm.

[0098] In Example 4, the PDLC coating adhesive prepared in Preparation Example 4 was used; the thickness of the resulting PDLC layer was measured to be 6 ± 0.5 μm.

[0099] In Example 5, the PDLC coating adhesive prepared in Preparation Example 5 was used; the thickness of the resulting PDLC layer was measured to be 6 ± 0.5 μm.

[0100] In Example 6, the PDLC coating adhesive prepared in Preparation Example 6 was used; the thickness of the resulting PDLC layer was measured to be 6 ± 0.5 μm.

[0101] In Example 7, the PDLC coating adhesive prepared in Preparation Example 7 was used; the thickness of the resulting PDLC layer was measured to be 6 ± 0.5 μm.

[0102] In Example 8, the PDLC coating adhesive prepared in Preparation Example 8 was used; the thickness of the resulting PDLC layer was measured to be 6 ± 0.5 μm.

[0103] Comparative Examples 1-5 are based on Example 1, the difference being that the source of the PDLC coating adhesive is different in step (1), while the other steps remain the same as in Example 1. Specifically,

[0104] In Comparative Example 1, the PDLC coating adhesive prepared in Comparative Example 1 was used; the thickness of the obtained PDLC layer was measured to be 6±0.5μm.

[0105] In Comparative Example 2, the PDLC coating adhesive prepared in Comparative Example 2 was used; the thickness of the obtained PDLC layer was measured to be 6±0.5μm.

[0106] In Comparative Example 3, the PDLC coating adhesive prepared in Comparative Example 3 was used; the thickness of the obtained PDLC layer was measured to be 6±0.5μm.

[0107] In Comparative Example 4, the PDLC coating adhesive prepared in Comparative Example 4 was used; the thickness of the obtained PDLC layer was measured to be 6±0.5μm.

[0108] In Comparative Example 5, the PDLC coating adhesive prepared in Comparative Example 5 was used; the thickness of the obtained PDLC layer was measured to be 6±0.5μm.

[0109] Performance testing was conducted on the electrochromic color-changing films prepared in Examples 1-8 and Comparative Examples 1-5. The test results are shown in Table 2 below.

[0110] Haze Change Rate Test: The electrochromic color-changing films prepared in Examples 1-8 and Comparative Examples 1-5 were cut into samples with a length of 100 mm and a width of 100 mm, with 3 samples corresponding to each experimental group. Under conditions of 25°C and driven by 48VAC and 60Hz, the haze (H0) of each sample in the hazy state and the haze (H1) in the transparent state were measured using a haze meter. The haze change rate ∆Haze of each sample was obtained, and the average value of the test results was taken. The formula for calculating the haze change rate ∆Haze is as follows:

[0111] ΔHaze=(H0-H1)÷H0×100%.

[0112] Withstand voltage breakdown test: The electrochromic color-changing films prepared in Examples 1-8 and Comparative Examples 1-5 were cut into samples with a length of 300 mm and a width of 300 mm. Three samples were prepared for each experimental group. The driving voltage was gradually increased until the film layer was broken down. The breakdown voltage was recorded and the average value of the test results was taken.

[0113] Table 2. Photoelectric properties of electrochromic color-changing films

[0114]

[0115] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the principles of this application should be covered within the scope of protection of this application.

Claims

1. A PDLC coating glue, characterized in that, The raw materials include the following parts by weight: 20-30 parts of acrylate oligomer, 30-60 parts of primary acrylate monomer, 15-40 parts of secondary acrylate monomer, 0.5-2.0 parts of silane-modified nano-scale inorganic filler, 50-60 parts of nematic liquid crystal, 0.5-2.0 parts of photoinitiator, and 1.5-2.4 parts of carboxyl-containing auxiliaries; The acrylate oligomers include polycaprolactone-type polyurethane acrylate oligomers and polyether-type polyurethane acrylate oligomers, wherein the weight ratio of the polycaprolactone-type polyurethane acrylate oligomers to the polyether-type polyurethane acrylate oligomers is (2.5~3.5):1; the raw materials for preparing the polycaprolactone-type polyurethane acrylate oligomers include polycaprolactone diol, hexamethylene diisocyanate, and 4-hydroxybutyl acrylate; the raw materials for preparing the polyether-type polyurethane acrylate oligomers include tetrahydrofuran homopolymer ether, hexamethylene diisocyanate, and hydroxyethyl methacrylate. The first acrylate monomer includes acrylate containing an alkyl chain, 1,3-propylene glycol diacrylate, and hydroxyethyl methacrylate; The second acrylate monomer includes tetrahydrofuran acrylate, benzyl methacrylate, methyl 2-[(2-propen-1-yloxy)methyl]-2-acrylate and o-phenylphenoxyethyl acrylate; The acrylate containing an alkyl chain is a tridecyl acrylate; The raw materials for preparing the silane-modified nanoscale inorganic filler include nanoscale silica and silane coupling agent; the weight ratio of the second acrylate monomer to the silane-modified nanoscale inorganic filler is 25:1, 30:1, or 20:

1.

2. The PDLC coating glue according to claim 1, characterized in that, The preparation method of the polycaprolactone-type polyurethane acrylate oligomer includes the following steps: mixing polycaprolactone diol with hexamethylene diisocyanate, stirring, adding an organotin catalyst, controlling the temperature at 40~50℃, reacting for 1.5~2.5h, controlling the temperature at 50~60℃, adding 4-hydroxybutyl acrylate and hydroquinone, maintaining the temperature at 50~60℃, reacting for 1.5~2.5h, controlling the temperature at 65~70℃, reacting for 2~3h, to obtain the polycaprolactone-type polyurethane acrylate oligomer; wherein, the mass ratio of polycaprolactone diol, hexamethylene diisocyanate and 4-hydroxybutyl acrylate is (400~550):(350~400):(280~290); and / or, The method for preparing the polyether-type polyurethane acrylate oligomer includes the following steps: providing tetrahydrofuran homopolymer, adding an organotin catalyst, stirring, adding hexamethylene diisocyanate dropwise, reacting at 55-60°C for 2-3 hours, controlling the temperature at 60-70°C, adding hydroxyethyl methacrylate dropwise, and simultaneously adding hydroquinone, controlling the temperature at 65-70°C, reacting for 2-3 hours to obtain the polyether-type polyurethane acrylate oligomer; wherein the mass ratio of tetrahydrofuran homopolymer, hexamethylene diisocyanate, and hydroxyethyl methacrylate is 98:(53-55):(45-47).

3. The PDLC coating adhesive according to claim 1, characterized in that, The weight ratio of the acrylate oligomer to the first acrylate monomer is (0.5~0.7):

1.

4. The PDLC coating adhesive according to claim 1, characterized in that, In the first acrylate monomer, the weight ratio of alkyl-containing acrylate, 1,3-propylene glycol diacrylate and hydroxyethyl methacrylate is (1.8~2.2):1:

1.

5. The PDLC coating adhesive according to claim 1, characterized in that, In the second acrylate monomer, the weight ratio of tetrahydrofuran acrylate, benzyl methacrylate, methyl 2-[(2-propen-1-yloxy)methyl]-2-acrylate and o-phenylphenoxyethyl acrylate is 1:(0.5~0.7):(1.4~1.6):

1.

6. A method for preparing a PDLC coating adhesive as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Under light-protected conditions, mix the acrylate oligomer, the first acrylate monomer, the second acrylate monomer, the silane-modified nano-sized inorganic filler, the photoinitiator, and the carboxyl-containing auxiliary agent, and stir at a stirring rate of 300-500 rpm for 30-60 min. Under vacuum conditions, stir at a stirring rate of 2000-2500 rpm for 6-10 min to obtain component A. S2. Place the nematic liquid crystal in an environment of 20~23℃ and let it stand for 30~90 min to obtain component B; S3. Place component A obtained in step S1 in a light-proof environment at a temperature of 20~23℃ and stir at a stirring rate of 200~400rpm. Add component B obtained in step S2 to component A and continue stirring for 60~120min to obtain the PDLC coating adhesive.

7. A method for preparing an electrochromic color-changing film using the PDLC coating adhesive as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) In an environment with a temperature of 20~23℃, the spacer is added to the PDLC coating adhesive and stirred to obtain the pre-coated adhesive, wherein the weight ratio of the spacer to the PDLC coating adhesive is (0.1~0.4):100; (2) Provide two transparent conductive films distributed vertically, and uniformly apply the pre-coated adhesive obtained in step (1) onto the lower transparent conductive film, and cover the upper transparent conductive film onto the pre-coated adhesive to form a wet film between the two transparent conductive films. (3) The wet film obtained in step (2) is pressed and cured with ultraviolet light to obtain an electrochromic color-changing film. The wet film is formed into a PDLC layer with a thickness of 6±0.5μm. The ultraviolet curing conditions are: ultraviolet light intensity of 12~15mW / cm². 2 The curing time is 2-4 minutes.

8. An electrochromic color-changing film prepared by the method described in claim 7.

9. The application of the electrochromic color-changing film as described in claim 8 in smart windows, flexible display devices, or optical modulation devices.

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