A pdlc and liquid crystal handwriting tablet composition with high peel strength and a preparation method thereof

Abstract

The application discloses a PDLC with high peeling strength and a liquid crystal handwriting board composition and a preparation method. The polymer monomer contained in the PDLC comprises acrylamide monomers, and the acrylamide monomers account for 5-20% of the total mass of the polymer monomers. The acrylamide monomers are introduced into the PDLC and the liquid crystal handwriting board system. The amide bond in the acrylamide monomers can act as a hydrogen bond donor and a hydrogen bond acceptor, and forms a dense dynamic hydrogen bond physical crosslinking network in the polymer network. The network has the following double enhancement mechanism: enhancing polymer cohesion: the hydrogen bond network and the chemical crosslinking network synergistically form strong enhancement units and energy dissipation points in the polymer matrix, and significantly improve the cohesion between the polymers; the N-H and C=O in the amide bond act as a hydrogen bond donor and an acceptor respectively, can form dense hydrogen bond and dipole interaction with the oxygen atoms on the surface of the ITO substrate, and generate stronger physical adsorption and energy dissipation at the interface.

Description

Technical Field

[0001] This invention relates to the field of polymer-dispersed liquid crystal materials technology, specifically to a PDLC and liquid crystal writing tablet composition with high peel strength and its preparation method. Background Technology

[0002] Polymer-dispersed liquid crystal (PDLC) is a composite material in which liquid crystals are encapsulated within a polymer matrix using phase separation technology to form discrete micron-sized droplets. PDLC achieves reversible switching between an optically scattering state and a transparent state by controlling the orientation of the liquid crystal molecules through an applied electric field: initially, due to the disordered orientation of the liquid crystals and the difference in refractive index between the liquid crystals and the polymer, a dark scattering state is formed; applying an electric field aligns the liquid crystals, matching their refractive index with the polymer, forming a bright, transmissive state; removing the electric field restores the disordered orientation of the liquid crystals, reverting to the scattering state. Based on this characteristic, PDLC has broad market prospects in optical and electronic applications such as architectural smart windows, automotive windows, displays, and sensors.

[0003] Currently, PDLC technology is relatively mature and has achieved industrial-scale production. Existing PDLCs are mainly prepared using acrylate olefin monomers through free radical polymerization to induce phase separation. However, acrylate polymers have inherent performance defects: large volume shrinkage during polymerization, brittle material texture, and poor adhesion to substrates. These defects limit the widespread use of PDLCs in applications requiring high mechanical properties, such as flexible wearable devices.

[0004] To improve the mechanical properties of PDLC, various improvement schemes have been explored in existing technologies. For example, surface modification of the substrate can be used to enhance the interfacial adhesion between the polymer and the substrate; or rigid groups can be introduced into the polymer system to increase the glass transition temperature of the polymer, thereby enhancing the cohesive force of the polymer matrix; in addition, some studies have used hydroxylated acrylate monomers to enhance the interfacial bonding force by utilizing the interaction between hydroxyl groups and the ITO layer of the substrate.

[0005] However, while the aforementioned methods improve mechanical properties, they often fail to simultaneously guarantee the optoelectronic performance of the device. For example, surface modification may increase process complexity and yield unstable results, while introducing rigid groups can lead to decreased film flexibility and increased driving voltage. Furthermore, the interfacial bonding force formed solely by hydroxyl groups is insufficient to meet the application requirements for high peel strength. Therefore, how to significantly improve the peel strength of PDLC films while ensuring good optoelectronic performance remains a pressing technical problem to be solved in this field.

[0006] Therefore, developing a PDLC material and liquid crystal writing board that combines good optoelectronic properties with excellent mechanical properties, especially high peel strength, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a PDLC and liquid crystal writing board composition with high peel strength and a preparation method thereof, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a PDLC with high peel strength, wherein adding an appropriate amount of acrylamide monomer can significantly improve the peel strength of the device while maintaining high contrast.

[0009] Polymer dispersed liquid crystal (PDLC) and liquid crystal writing tablets have a sandwich structure, with the top and bottom layers being PET substrates with ITO, and the middle layer being a polymer liquid crystal layer. The main difference between PDLC and liquid crystal writing tablets lies in the middle polymer liquid crystal layer (PDLC uses nematic liquid crystal, while liquid crystal writing tablets use cholesteric liquid crystal), and liquid crystal writing tablets often use black PET as the base film;

[0010] The polymer monomers contained in the PDLC include acrylamide monomers, which account for 5% to 20% of the total mass of the polymer monomers and have at least one of the following structural formulas:

[0011] ,

[0012] in:

[0013] ;

[0014] ,

[0015] Where m is less than or equal to 10;

[0016]

[0017] Where m is less than or equal to 10;

[0018]

[0019] or

[0020] ;

[0021] Where m is less than or equal to 10;

[0022] or ;

[0023] .

[0024] Further, by weight, it includes 15-60 parts of polymer monomer and 40-85 parts of nematic liquid crystal; it also includes spacer particles and a photoinitiator, wherein the mass of the spacer particles is 2‰-5‰ of the mass of the nematic liquid crystal, and the mass of the photoinitiator is 5‰-3% of the mass of the polymer monomer; the polymer monomer also includes monofunctional acrylate monomers, difunctional acrylate monomers, polyfunctional acrylate monomers, and polyurethane acrylate oligomers.

[0025] Furthermore, the mass ratio of acrylamide monomers, monofunctional acrylate monomers, difunctional acrylate monomers, polyfunctional acrylate monomers and polyurethane acrylate oligomers in the polymer monomers is (0.5-3):(1-4):(1-3):(0-2):(1-5).

[0026] Furthermore, the monofunctional acrylate monomers include one or more of isobornyl acrylate, isobornyl methacrylate, lauryl methacrylate, lauryl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, isodecyl methacrylate, and isodecyl acrylate.

[0027] Furthermore, the difunctional acrylate monomers include one or more of 1,6-hexanediol diacrylate, polyethylene glycol 200 diacrylate, polyethylene glycol 400 diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and 1,4-butanediol diacrylate.

[0028] Furthermore, the polyfunctional acrylate monomers include one or more of pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylate, and ethoxylated trimethylolpropane trimethacrylate.

[0029] Further, the polyurethane acrylate oligomer includes one or more of W2001, W2006, W3001, and W3003, with a functionality ≤6; the photoinitiator includes one or two of Irgacure TPO, Irgacure 651, BME, I2959, ITX, and 184; and the spacer particles include silica or polystyrene, with a diameter of 2-30 μm.

[0030] A method for preparing PDLC with high peel strength involves uniformly mixing nematic liquid crystal, polymer monomer, spacer particles and photoinitiator in a light-protected environment to obtain a mixed solution; pressing the mixed solution into a sandwich structure using a roll-to-roll process and then curing it with ultraviolet light to obtain the PDLC with high peel strength.

[0031] A method for preparing a liquid crystal handwriting board involves uniformly distributing the aforementioned PDLC with high peel strength between two PET films containing ITO on their surfaces using a roll-to-roll device, followed by free radical polymerization initiated by ultraviolet light. The hydrogen bond network formed by acrylamide monomers in the PDLC is utilized to improve the peel strength of the device, thus obtaining the liquid crystal handwriting board.

[0032] The distribution of the PDLC with high peel strength between two PET films containing ITO on their surfaces is 6.67 g / m²-33.33 g / m²; the ultraviolet light is 365 nm light with an intensity of 2-30 mW / cm² and a duration of 1-20 min.

[0033] A liquid crystal handwriting tablet is prepared by the above-described method.

[0034] Acrylamide monomers were mixed with olefin monomers, oligomers, liquid crystals, spacers, and photoinitiators. The mixture was then roll-coated and cured under 365 nm UV light. The amide bonds in the acrylamide monomers form numerous hydrogen bonds, increasing the number of physical crosslinking points and enhancing the cohesive force between polymers. Furthermore, the NH and C=O atoms in the amide bonds act as hydrogen bond donors and acceptors, respectively, forming dense hydrogen bonds and dipole interactions with oxygen atoms on the ITO surface. This results in stronger physical adsorption and energy dissipation at the interface, significantly improving adhesion. Through the synergistic effect of these two factors, the mechanical properties of the device are improved.

[0035] Polymer dispersed liquid crystals (PDLCs) and liquid crystal writing tablets, as typical binary composite materials, are primarily governed by the three-dimensional network structure formed by the polymer matrix as the continuous phase. The liquid crystal droplets dispersed within the matrix exert a significant plasticizing effect on the polymer molecular chain motion through interfacial interactions, thereby microscopically regulating the crosslinking density and chain segment relaxation behavior of the composite system, ultimately determining its macroscopic modulus, toughness, and viscoelastic behavior. The mechanical properties of flexible devices such as PDLCs and liquid crystal writing tablets are mainly related to the cohesive force between polymers and the adhesion force between the polymer and the substrate. Adhesion and cohesion can be improved in different ways. Adhesion can be improved through substrate modification, while cohesion can be improved by introducing rigid groups. Increasing the glass transition temperature of the polymer system increases its rigidity, thereby increasing the cohesive force between polymers and improving the mechanical properties of PDLCs and liquid crystal writing tablets. Hydroxylated acrylate monomers enhance the interaction between the polymer and the ITO layer on the substrate through the hydroxyl groups in the system, improving the device's mechanical properties and, to some extent, increasing the cohesive force between the polymer networks. However, these methods have limited impact on mechanical properties and it is difficult to balance the mechanical and optoelectronic properties of thin-film devices.

[0036] For acrylamide monomers, the side chains of their polymers contain amide bonds. These amide bonds act as both hydrogen bond donors and acceptors, enabling abundant hydrogen bond interactions between polymer chains and between the polymer and substrate. This results in a dense hydrogen-bonded physical cross-linked network within the PDLC polymer network, significantly enhancing the cohesive force of the polymer matrix and the interfacial bonding between the polymer and the substrate.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] The present invention has the following beneficial effects:

[0039] This invention introduces acrylamide monomers into PDLC and liquid crystal handwriting tablet systems. The amide bonds in the acrylamide monomers can act as both hydrogen bond donors and acceptors, forming a dense, dynamic, physically cross-linked network of hydrogen bonds within the polymer network. This network possesses the following dual enhancement mechanism:

[0040] Enhancing polymer cohesion: The synergistic effect of hydrogen bond networks and chemical cross-linking networks forms strong reinforcing units and energy dissipation points in the polymer matrix, significantly improving the cohesive force between polymers;

[0041] Enhanced interfacial adhesion: The NH and C=O in the amide bond act as hydrogen bond donors and acceptors, respectively, and can form dense hydrogen bonds and dipole interactions with oxygen atoms on the surface of the ITO substrate, resulting in stronger physical adsorption and energy dissipation at the interface.

[0042] While maintaining excellent optoelectronic performance, this invention significantly improves the peel strength and shear strength of PDLC and liquid crystal handwriting tablets, solving the technical problems of insufficient mechanical properties and difficulty in balancing optoelectronic performance in the prior art, and has broad prospects for industrial application. Attached Figure Description

[0043] Figure 1 This is a graph showing the peel strength and shear strength of the PDLC of the present invention with different types of difunctional acrylamide monomers;

[0044] Figure 2 This is a graph showing the peel strength and shear strength of the PDLC of the present invention with different types of monofunctional acrylamide monomers;

[0045] Figure 3 This is a peel strength diagram of the PDLC of the present invention as a function of monomer content;

[0046] Figure 4 This is a shear strength diagram of the PDLC of the present invention as a function of monomer content;

[0047] Figure 5 This is a peel strength diagram of the PDLC of the present invention as a function of the content of bifunctional acrylamide monomers;

[0048] Figure 6 This is a shear strength diagram of the PDLC of the present invention as a function of the content of bifunctional acrylamide monomers;

[0049] Figure 7 The diagram shows the driving voltage-transmittance (VT) of the PDLC of this invention with different types of difunctional acrylamide monomers;

[0050] Figure 8 The diagram shows the driving voltage-transmittance (VT) of the PDLC of this invention with different types of monofunctional acrylamide monomers;

[0051] Figure 9 This is a schematic diagram and physical image of the PDLC device of this invention. It is transparent when powered on and atomized when powered off.

[0052] Figure 10 The schematic diagram of the liquid crystal writing tablet of this invention mainly utilizes the transition between the planar textured state (P state) and the focal conic state (FC state) of cholesteric liquid crystal to achieve writing by pressing (the area after pressing is in the P state) and erasing by applying electricity (the entire area is in the FC state after applying electricity), and peel strength. F represents the average peel strength, b represents the adhesive width, Toff represents the light transmittance of PDLC without an applied electric field (off-state transmittance), Ton represents the light transmittance of PDLC under saturation voltage (on-state transmittance), Vth represents the threshold voltage, which is the voltage required when the light transmittance of PDLC reaches 10% of Ton, Vsat represents the saturation voltage, which is the voltage required when the light transmittance of PDLC reaches 90% of Ton, and CR represents the contrast ratio, which is calculated as: CR = Ton / Toff. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] Please see Figure 1-10 A PDLC and liquid crystal writing tablet composition with high peel strength and a method for preparation thereof, wherein the polymer monomers contained in the PDLC include acrylamide monomers, the acrylamide monomers accounting for 5% to 20% of the total mass of the polymer monomers, and having at least one of the following structural formulas:

[0055] ,

[0056] in:

[0057] ;

[0058] ,

[0059] Where m is less than or equal to 10;

[0060]

[0061] Where m is less than or equal to 10;

[0062]

[0063] or

[0064] ;

[0065] Where m is less than or equal to 10;

[0066] or ;

[0067] .

[0068] Example 1

[0069] The liquid crystal layer, by weight, comprises 55 parts nematic liquid crystal and 45 parts polymer monomer, and also includes spacer particles and a photoinitiator. The mass of the spacer particles is 5‰ of the mass of the liquid crystal, and the mass of the photoinitiator is 2% of the mass of the polymer monomer.

[0070] The polymer monomers include difunctional acrylamide monomers, lauryl acrylate, 2-phenoxyethyl acrylate, glycidyl methacrylate, and difunctional polyurethane acrylate (W2240), and the mass ratio is 10:35:5:5:45.

[0071] The difunctional acrylamide monomers are:

[0072] N,N′-methylenebisacrylamide, its structural formula is:

[0073] ;

[0074] N,N′-vinylbisacrylamide, its structural formula is:

[0075] ;

[0076] Hexamethylenebisacrylamide, its structural formula is:

[0077] ;

[0078] 1,6-Hexanediol diacrylate, its structural formula is:

[0079] ;

[0080] The ultraviolet photoinitiator is TPO, namely diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide. The spacer particles are silicon dioxide with a diameter of 20 μm. The nematic liquid crystal is E7.

[0081] The preparation method of polymer-dispersed liquid crystal (PDLC) is as follows:

[0082] Nematic liquid crystal, polymer monomer, spacer particles and photoinitiator are mixed in a light-protected environment to obtain a mixture;

[0083] The mixture obtained above was uniformly distributed between two PET films with ITO on their surfaces using a roll-to-roll apparatus, and then subjected to free radical polymerization initiated by ultraviolet light. The ultraviolet light was 365 nm, with an intensity of 5 mW / cm², and the time was 5 min. The distribution of the mixture between the films was 16.7 g / m². Both flexible PET films with ITO conductive layers were transparent.

[0084] Example 2

[0085] The liquid crystal layer, by weight, comprises 65 parts nematic liquid crystal and 35 parts polymer monomer, and also includes spacer particles and a photoinitiator. The mass of the spacer particles is 5‰ of the mass of the liquid crystal, and the mass of the photoinitiator is 1% of the mass of the polymer monomer.

[0086] The polymer monomers include monofunctional acrylamide monomers, tert-butyl acrylate, lauryl methacrylate, butyl methacrylate, isodecyl acrylate, and difunctional polyurethane acrylate (W2006), with a mass ratio of 8:40:15:10:10:17.

[0087] The monofunctional acrylamide monomers are:

[0088] N-hydroxyethyl methacrylate, its structural formula is:

[0089] ;

[0090] N-hydroxyethylacrylamide has the following structural formula:

[0091] ;

[0092] Hydroxyethyl acrylate, its structural formula is:

[0093] ;

[0094] Hydroxyethyl methacrylate,

[0095] ;

[0096] The ultraviolet photoinitiator is TPO, namely diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide. The spacer particles are silicon dioxide with a diameter of 20 μm. The nematic liquid crystal is E7.

[0097] The preparation method of polymer-dispersed liquid crystal (PDLC) is as follows:

[0098] Nematic liquid crystal, polymer monomer, spacer particles and photoinitiator are mixed in a light-protected environment to obtain a mixture.

[0099] The mixture obtained above was uniformly distributed between two PET films with ITO on their surfaces using a roll-to-roll apparatus, and then subjected to free radical polymerization initiated by ultraviolet light. The ultraviolet light was 365 nm, with an intensity of 10 mW / cm², and the time was 5 min. The distribution of the mixture between the films was 16.7 g / m². Both flexible PET films with ITO conductive layers were transparent.

[0100] Example 3

[0101] The liquid crystal layer, by weight, comprises 60 parts nematic liquid crystal and 40 parts polymer monomer, and also includes spacer particles and a photoinitiator. The mass of the spacer particles is 5‰ of the mass of the liquid crystal, and the mass of the photoinitiator is 1.5% of the mass of the polymer monomer.

[0102] The polymer monomers include bifunctional acrylamide monomers, isobornyl methacrylate, cyclohexyl methacrylate, polyethylene glycol 400 diacrylate, 1,4-bis(acryloyloxy)butane, and bifunctional polyurethane acrylate (W2001), with a mass ratio of 15:40:5:10:10:5:15.

[0103] The difunctional acrylamide monomers are:

[0104] N,N′-vinylbisacrylamide, its structural formula is:

[0105] ;

[0106] The ultraviolet photoinitiators are photoinitiators 651 and 184. The spacer particles are polystyrene with a diameter of 15 μm. The nematic liquid crystal is E7.

[0107] The preparation method of polymer-dispersed liquid crystal (PDLC) is as follows:

[0108] The nematic liquid crystal, polymer monomer, spacer particles and photoinitiator are mixed in a light-protected environment to obtain a mixture.

[0109] The mixture obtained above was uniformly distributed between two PET films with ITO on their surfaces using a roll-to-roll apparatus, and then subjected to free radical polymerization initiated by ultraviolet light. The ultraviolet light was 365 nm, with an intensity of 5 mW / cm², and the time was 5 min. The distribution of the mixture between the films was 16.7 g / m². Both flexible PET films with ITO conductive layers were transparent.

[0110] Example 4

[0111] The liquid crystal layer, by weight, comprises 60 parts nematic liquid crystal and 40 parts polymer monomer, and also includes spacer particles and a photoinitiator. The mass of the spacer particles is 5‰ of the mass of the liquid crystal, and the mass of the photoinitiator is 1.5% of the mass of the polymer monomer.

[0112] The polymer monomers include difunctional acrylamide monomers, lauryl methacrylate, hydroxyethyl acrylate, and difunctional polyurethane acrylate (W3001), with a mass ratio of 15:50:5:30.

[0113] The difunctional acrylamide monomers are:

[0114] Hexamethylenebisacrylamide, its structural formula is:

[0115] ;

[0116] The ultraviolet photoinitiator is photoinitiator BME and 184. The spacer particles are silicon dioxide with a diameter of 15 μm. The nematic liquid crystal is E01.

[0117] The preparation method of polymer-dispersed liquid crystal (PDLC) is as follows:

[0118] Nematic liquid crystal, polymer monomer, spacer particles and photoinitiator are mixed in a light-protected environment to obtain a mixture.

[0119] The mixture obtained above was uniformly distributed between two PET films with ITO on their surfaces using a roll-to-roll apparatus, and then subjected to free radical polymerization initiated by ultraviolet light. The ultraviolet light was 365 nm, with an intensity of 5 mW / cm², and the time was 5 min. The distribution of the mixture between the films was 16.7 g / m². Both flexible PET films with ITO conductive layers were transparent.

[0120] Example 5

[0121] The liquid crystal layer, by weight, comprises 60 parts nematic liquid crystal and 40 parts polymer monomer, and also includes spacer particles and a photoinitiator. The mass of the spacer particles is 5‰ of the mass of the liquid crystal, and the mass of the photoinitiator is 1.5% of the mass of the polymer monomer.

[0122] The polymer monomers include difunctional acrylamide monomers, isobornyl acrylate, hydroxyethyl acrylate, 2-phenoxyethyl acrylate, ethylene glycol phenyl ether methacrylate, ethoxyphenoxy acrylate, and difunctional polyurethane acrylate (W3003), and the mass ratio is 15:48:5:8:8:4:12.

[0123] The difunctional acrylamide monomers are:

[0124] N,N′-(1,2-dihydroxyethylene)diacrylamide, its structural formula is:

[0125] ;

[0126] The ultraviolet photoinitiator is photoinitiator TPO and 184. The spacer particles are silicon dioxide with a diameter of 20 μm. The nematic liquid crystal is E8.

[0127] The preparation method of polymer-dispersed liquid crystal (PDLC) is as follows:

[0128] Nematic liquid crystal, polymer monomer, spacer particles and photoinitiator are mixed in a light-protected environment to obtain a mixture.

[0129] The mixture obtained above was uniformly distributed between two PET films with ITO on their surfaces using a roll-to-roll apparatus, and then subjected to free radical polymerization initiated by ultraviolet light. The ultraviolet light was 365 nm, with an intensity of 5 mW / cm², and the time was 5 min. The distribution of the mixture between the films was 16.7 g / m². Both flexible PET films with ITO conductive layers were transparent.

[0130] Example 6

[0131] The liquid crystal layer, by weight, comprises 65 parts of nematic liquid crystal and 35 parts of polymer monomer, 60 parts of nematic liquid crystal and 40 parts of polymer monomer, 55 parts of nematic liquid crystal and 45 parts of polymer monomer, and 50 parts of nematic liquid crystal and 50 parts of polymer monomer, and also includes spacer particles and a photoinitiator. The mass of the spacer particles is 5‰ of the mass of the liquid crystal, and the mass of the photoinitiator is 1% of the mass of the polymer monomer.

[0132] The polymer monomers include N,N′-methylenebisacrylamide, isobornyl acrylate, hydroxyethyl methacrylate, and difunctional polyurethane acrylate (W2005) in a mass ratio of 10:40:10:40.

[0133] The structural formula of the difunctional acrylamide monomer is:

[0134] ;

[0135] The ultraviolet photoinitiator is TPO. The spacer particles are silicon dioxide with a diameter of 20 μm. The nematic liquid crystal is E7.

[0136] The preparation method of polymer-dispersed liquid crystal (PDLC) is as follows:

[0137] Nematic liquid crystal, polymer monomer, spacer particles and photoinitiator are mixed in a light-protected environment to obtain a mixture.

[0138] The mixture obtained above was uniformly distributed between two PET films with ITO on their surfaces using a roll-to-roll apparatus, and then subjected to free radical polymerization initiated by ultraviolet light. The ultraviolet light was 365 nm, with an intensity of 10 mW / cm², and the time was 5 min. The distribution of the mixture between the films was 16.7 g / m². Both flexible PET films with ITO conductive layers were transparent.

[0139] Example 7

[0140] The liquid crystal layer, by weight, comprises 60 parts nematic liquid crystal and 40 parts polymer monomer, and also includes spacer particles and a photoinitiator. The mass of the spacer particles is 5‰ of the mass of the liquid crystal, and the mass of the photoinitiator is 1.5% of the mass of the polymer monomer.

[0141] The polymer monomers include bifunctional acrylamide monomers, tetrahydrofuran acrylate, hydroxyethyl methacrylate, isobornyl methacrylate, and bifunctional polyurethane acrylate (W2009), with mass ratios of 5:30:20:5:20:20, 10:25:20:5:20:20, 15:20:20:5:20:20, and 25:15:20:5:20:20.

[0142] The difunctional acrylamide monomers are:

[0143] N,N′-methylenebisacrylamide, its structural formula is:

[0144] ;

[0145] The ultraviolet photoinitiators are photoinitiators I2959 and 184. The spacer particles are silicon dioxide with a diameter of 20 μm. The nematic liquid crystal is E8.

[0146] The preparation method of polymer-dispersed liquid crystal (PDLC) is as follows:

[0147] Nematic liquid crystal, polymer monomer, spacer particles and photoinitiator are mixed in a light-protected environment to obtain a mixture.

[0148] The mixture obtained above was uniformly distributed between two PET films with ITO on their surfaces using a roll-to-roll apparatus, and then subjected to free radical polymerization initiated by ultraviolet light. The ultraviolet light was 365 nm, with an intensity of 5 mW / cm², and the time was 5 min. The distribution of the mixture between the films was 16.7 g / m². Both flexible PET films with ITO conductive layers were transparent.

[0149] Example 8

[0150] The liquid crystal layer, by weight, comprises 80 parts nematic liquid crystal and 20 parts polymer monomer, and also includes spacer particles and a photoinitiator. The mass of the spacer particles is 5‰ of the mass of the liquid crystal, and the mass of the photoinitiator is 1% of the mass of the polymer monomer.

[0151] The polymer monomers include difunctional acrylamide monomers, isodecanyl acrylate, 1,6-hexanediol diacrylate, o-phenylphenoxyethyl acrylate, ethoxyethoxyethyl acrylate, and difunctional polyurethane acrylate (W2005), with a mass ratio of 5:25:20:5:15:30.

[0152] The difunctional acrylamide monomers are:

[0153] N,N′-methylenebisacrylamide, its structural formula is:

[0154] ;

[0155] The ultraviolet photoinitiator is TPO. The spacer particles are silica with a diameter of 5 μm. The cholesteric liquid crystal is YO7.

[0156] The manufacturing method of the liquid crystal handwriting tablet is as follows:

[0157] Cholesteric liquid crystal, polymer monomer, spacer particles and photoinitiator were mixed in a light-protected environment to obtain a mixture.

[0158] The mixture obtained above was uniformly distributed between two PET films with ITO on their surfaces using a roll-to-roll apparatus, and then subjected to free radical polymerization initiated by ultraviolet light. The ultraviolet light was 365 nm, with an intensity of 5 mW / cm², and the time was 5 min. The distribution of the mixture between the films was 6.7 g / m². One of the two flexible PET films with an ITO conductive layer was black, and the other was transparent.

[0159] Example 9

[0160] The liquid crystal layer, by weight, comprises 80 parts nematic liquid crystal and 20 parts polymer monomer, and also includes spacer particles and a photoinitiator. The mass of the spacer particles is 4‰ of the mass of the liquid crystal, and the mass of the photoinitiator is 1% of the mass of the polymer monomer.

[0161] The polymer monomers include bifunctional acrylamide monomers, lauryl methacrylate, 1,6-hexanediol diacrylate, isooctyl methacrylate, butyl methacrylate, and bifunctional polyurethane acrylate (W3001), with a mass ratio of 12:34:25:9:10:10.

[0162] The difunctional acrylamide monomers are:

[0163] N,N′-(1,2-dihydroxyethylene)diacrylamide, its structural formula is:

[0164] ;

[0165] The ultraviolet photoinitiator is photoinitiator TPO and 184. The spacer particles are silicon dioxide with a diameter of 8 μm. The cholesteric liquid crystal is YO7.

[0166] The manufacturing method of the liquid crystal handwriting tablet is as follows:

[0167] Cholesteric liquid crystal, polymer monomer, spacer particles and photoinitiator were mixed in a light-protected environment to obtain a mixture.

[0168] The mixture obtained above was uniformly distributed between two PET films with ITO on their surfaces using a roll-to-roll apparatus, and then subjected to free radical polymerization initiated by ultraviolet light. The ultraviolet light was 365 nm, with an intensity of 5 mW / cm², and the time was 5 min. The distribution of the mixture between the films was 6.7 g / m². One of the two flexible PET films with an ITO conductive layer was black, and the other was transparent.

[0169] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A PDLC with high peel strength, characterized in that, The polymer monomers contained in the PDLC include acrylamide monomers, which account for 5% to 20% of the total mass of the polymer monomers and have at least one of the following structural formulas: ， in: ； ， Where m is less than or equal to 10; Where m is less than or equal to 10; or ； Where m is less than or equal to 10; or ; 。 2. The PDLC with high peel strength according to claim 1, characterized in that: By weight, it comprises 15-60 parts of polymer monomer and 40-85 parts of nematic liquid crystal; it also comprises spacer particles and photoinitiator, wherein the mass of the spacer particles is 2‰-5‰ of the mass of the nematic liquid crystal, and the mass of the photoinitiator is 5‰-3% of the mass of the polymer monomer; the polymer monomer further comprises monofunctional acrylate monomers, difunctional acrylate monomers, polyfunctional acrylate monomers, and polyurethane acrylate oligomers.

3. A PDLC with high peel strength according to claim 2, characterized in that: The mass ratio of acrylamide monomers, monofunctional acrylate monomers, difunctional acrylate monomers, polyfunctional acrylate monomers, and polyurethane acrylate oligomers in the polymer monomers is (0.5-3):(1-4):(1-3):(0-2):(1-5). The monofunctional acrylate monomers include one or more of isoborneol acrylate, isoborneol methacrylate, lauryl methacrylate, lauryl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, isodecyl methacrylate, and isodecyl acrylate.

4. A PDLC with high peel strength according to claim 2, characterized in that: The difunctional acrylate monomers include one or more of 1,6-hexanediol diacrylate, polyethylene glycol 200 diacrylate, polyethylene glycol 400 diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and 1,4-butanediol diacrylate; the polyfunctional acrylate monomers include one or more of pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and trimethylolpropane trimethacrylate.

5. A PDLC with high peel strength according to claim 2, characterized in that: The polyurethane acrylate oligomer includes one or more of W2001, W2006, W3001, and W3003, with a functionality ≤6. The photoinitiator includes one or two of Irgacure TPO, Irgacure 651, BME, I2959, ITX, and 184. The spacer particles include silica or polystyrene, and the diameter of the spacer particles is 2-30 μm.

6. A method for preparing PDLC with high peel strength as described in any one of claims 1-5, characterized in that, In a light-protected environment, nematic liquid crystal, polymer monomer, spacer particles and photoinitiator are mixed evenly to obtain a mixed solution; the mixed solution is pressed into a sandwich structure by a roll-to-roll process and then cured with ultraviolet light to obtain the PDLC with high peel strength.

7. A method for preparing a liquid crystal handwriting tablet, characterized in that, The PDLC with high peel strength according to any one of claims 1-5 is uniformly distributed between two PET films containing ITO on the surface through a roll-to-roll device, and then free radical polymerization is initiated by ultraviolet light. The hydrogen bond network formed by acrylamide monomers in the PDLC is used to improve the peel strength of the device, thus obtaining a liquid crystal handwriting board. The distribution of the PDLC with high peel strength between two PET films containing ITO on their surfaces is 6.67 g / m²-33.33 g / m²; the ultraviolet light is 365 nm light with an intensity of 2-30 mW / cm² and a duration of 1-20 min.

8. A liquid crystal handwriting tablet, characterized in that, It is prepared by the preparation method described in claim 7.

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