A kind of reverse electric control dimming film and preparation method thereof

Abstract

The embodiment of the present invention discloses a trans-electrically controlled dimming film and a preparation method thereof, which belongs to the technical field of liquid crystal materials. The trans-electrically controlled dimming film includes a first transparent conductive film, a second transparent conductive film and a polymer liquid crystal film, the polymer liquid crystal film is composited between the first transparent conductive film and the second transparent conductive film to form a layered structure, the polymer liquid crystal film is prepared using a photomask, and its component raw materials include 10-40 parts by weight of ultraviolet light polymerizable monomers; 60-90 parts by weight of liquid crystals and an appropriate amount of ultraviolet light initiator and salt ions. The preparation method includes the steps of: mixing ultraviolet light polymerizable monomers, salt ions, liquid crystals and ultraviolet light initiators and loading them into a liquid crystal box to vertically align the liquid crystal molecules; then covering the liquid crystal box with a photomask and performing ultraviolet curing to obtain the trans-electrically controlled dimming film. The trans-electrically controlled dimming film prepared by the embodiment of the present invention has a high polymer monomer content and excellent cycle stability of electro-optical performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid crystal materials, and in particular relates to a reverse electrically controlled dimming film and a preparation method thereof. Background Art

[0002] With the development of social economy, environmental protection and intelligent materials are increasingly used in life. Smart windows can regulate the intensity of solar radiation entering the room according to changes in electric field, temperature, etc., thereby greatly reducing the energy consumption for adjusting indoor lighting, heating and cooling. They have been widely used in the automotive industry, construction industry and other fields. As a key material for preparing smart windows, dimming films can be divided into formal dimming films and reverse dimming films according to the state changes after power is turned on. Among them, the formal dimming film changes in the state of "frosted when off and transparent when on", and the reverse dimming film changes in the state of "transparent when off and frosted when on". In practical applications, most environments need to maintain a transparent state for a long time and over a large area. The use of formal dimming films will not only cause energy waste, but also damage to the power supply of the dimming film will cause the dimming film to stagnate in the frosted state, which is easy to cause more serious consequences in some application scenarios (such as transportation). Therefore, it is necessary to pay attention to the research on reverse dimming films.

[0003] At present, the main material systems for preparing reverse dimming films include polymer stabilized liquid crystal (PSLC) systems based on nematic liquid crystal or cholesteric liquid crystal, including liquid crystal and polymer networks, polymers have specific orientation characteristics, such as parallel orientation and vertical orientation, etc.; liquid crystal is distributed in a continuous phase. Polymer-induced phase separation is often used to prepare PSLC films. First, liquid crystal and monomer / prepolymer are evenly mixed in a certain proportion to make the liquid crystal molecules form a certain orientation, and then heat or light is used to initiate the polymerization reaction. After the polymerization reaction, the molecular weight of the polymer increases, the mutual solubility between the polymer and the liquid crystal deteriorates, the two phases separate, the liquid crystal precipitates, and two separated phases are formed.

[0004] However, existing polymer liquid crystals generally use acrylate polymers as the polymer matrix. Since the content of polymer monomers is generally less than 10%, the formed polymer network is generally relatively thin. Long-term cyclic power supply not only easily causes the polymer network to break, but also seriously affects the transmittance and electro-optical performance. Summary of the invention

[0005] The object of the present invention is to provide a reverse electrically controlled dimming film and a preparation method thereof. The polymer liquid crystal film in the reverse electrically controlled dimming film is prepared by using a photomask, which can cause ultraviolet light polymerizable monomers to aggregate in the area not covered by the photomask to form a polymer wall structure, thereby making the polymer network more compact due to the increase in the content of ultraviolet light polymerizable monomers, thereby achieving better resistance to damage caused by cyclic power-on, and effectively solving the technical problem of the existing reverse dimming film that the polymer network is easily damaged during cyclic power-on due to the low content of polymer monomers.

[0006] In order to achieve the above object, the technical solution of the embodiment of the present invention is:

[0007] In a first aspect, an embodiment of the present invention provides a transverse electrically controlled dimming film, the transverse electrically controlled dimming film comprising a first transparent conductive film, a second transparent conductive film and a polymer liquid crystal film, wherein the polymer liquid crystal film is composited between the first transparent conductive film and the second transparent conductive film to form a layered structure;

[0008] The polymer liquid crystal film is prepared using a photomask, and its component raw materials include:

[0009] UV-polymerizable monomer, used in an amount of 10-40 parts by weight;

[0010] Liquid crystal, the amount of which is 60-90 parts by weight;

[0011] an ultraviolet light initiator, the amount of which is 0.1-5% of the total weight of the ultraviolet light polymerizable monomer and the liquid crystal; and

[0012] The mass ratio of the salt ion to the ultraviolet light polymerizable monomer is 1:1-100.

[0013] In combination with the first aspect, in a preferred implementation of the embodiment of the present invention, the UV light polymerizable monomer includes an acrylate having a first group and an acrylate having a second group, and the first group is the same as or different from the second group.

[0014] In combination with the first aspect, in a preferred embodiment of the present invention, when the first group is different from the second group, the weight ratio of the acrylate having the first group to the acrylate having the second group is 1-10:1-10.

[0015] In combination with the first aspect, in a preferred implementation of the embodiment of the present invention, the acrylate having the first group is 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate).

[0016] In combination with the first aspect, in a preferred embodiment of the present invention, the acrylate having a second group is selected from 4-cyanophenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate, 4-methoxyphenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate, 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)-2-fluorobenzoate), 4-((4-(3-(acryloyloxy)propoxy)benzoyl )oxy)-2-methylphenyl 4-(3-(buta-1,3-dien-2-yloxy)propoxy)benzoate, 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate), 2-methyl-1,4-phenylenebis(4-(4-(vinyloxy)butoxy)benzoate), 4-((4-((6-(acryloyloxy)hexyl)oxy)benzoyl)oxy)phenyl 4-(hexyloxy)benzoate.

[0017] In combination with the first aspect, in a preferred embodiment of the embodiment of the present invention, the liquid crystal is a negative nematic phase liquid crystal, and the crystallization point of the negative nematic phase liquid crystal is less than -40°C, the clearing point is greater than 100°C, the birefringence is greater than 0.1, the dielectric anisotropy is less than -0.5, and the viscosity is less than 200mP.s.

[0018] In combination with the first aspect, in a preferred implementation of the embodiment of the present invention, the salt ion is selected from at least one of hexadecyltrimethylammonium bromide, tetrabutylamine perchlorate and 2,3,5,6-tetracyanoquinone.

[0019] In combination with the first aspect, in a preferred embodiment of the present invention, the ultraviolet light initiator is selected from at least one of benzoin ethyl ether, benzophenone, thioanthrone, benzil dimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropanone, trimethylbenzoyl diphenyl phosphine oxide, and benzoin diethyl ether.

[0020] In a second aspect, an embodiment of the present invention further provides a method for preparing a reverse electrically controlled dimming film, comprising the following steps:

[0021] Mixing ultraviolet light polymerizable monomers, salt ions, liquid crystals and photoinitiators and loading them into a liquid crystal box, wherein the inner surfaces of two conductive glasses of the liquid crystal box are respectively coated with a first transparent conductive film and a second transparent conductive film;

[0022] The liquid crystal box is covered with a photomask and subjected to ultraviolet curing to obtain a reverse electrically controlled dimming film.

[0023] In combination with the first aspect, in a preferred embodiment of the present invention, the temperature of the UV curing is 0-80°C, the time is 1-30min, and the light intensity is 0.1-30mW / cm 2.

[0024] Compared with the prior art, the advantages or beneficial effects of the embodiments of the present invention include at least:

[0025] The trans-electrically controlled dimming film provided by the embodiment of the present invention uses 10-40 parts by weight of ultraviolet light polymerizable monomers, 60-90 parts by weight of liquid crystals, and an appropriate amount of ultraviolet light initiator and salt ions as raw materials, and prepares a polymer liquid crystal film that can be composited between a first transparent conductive film and a second transparent conductive film through a photomask, which can promote the ultraviolet light polymerizable monomers to aggregate in the area not covered by the photomask to form a polymer wall network structure, so that the polymer network is more compact due to the increase in the content of ultraviolet light polymerizable monomers, and the polymer network will no longer break due to too low a polymer monomer content, so that it can better resist the damage caused by cyclic power-on, and achieve the improvement of the stability of the electro-optical performance of the trans-electrically controlled dimming film during cyclic use.

[0026] (2) The method for preparing the reverse electric-controlled dimming film provided in the embodiment of the present invention is to mix the components and then pour them into the liquid crystal box to vertically align the liquid crystal molecules and cover them with a photomask, and then perform UV curing. The preparation process is simple and the curing time is short, which is suitable for the area production of the reverse electric-controlled dimming film. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 is a scanning electron microscope image of the microscopic morphology of the polymer network in the reverse electrically controlled dimming film A1 prepared in Example 1 of the present invention;

[0029] Figure 2 is a curve diagram of voltage-transmittance of the reverse electric-controlled dimming film A1 prepared in Example 1 of the present invention;

[0030] Figure 3 1 is a graph showing the cyclic stability of voltage-transmittance of the reverse electric-controlled dimming film A1 prepared in Example 1 of the present invention;

[0031] Figure 4 1 is a graph showing the cyclic stability of voltage-transmittance of the reverse electric-controlled dimming film D1 prepared in Comparative Example 1 of the present invention;

[0032] Figure 5 is a scanning electron microscope image of the microscopic morphology of the polymer network in the reverse electrically controlled dimming film A2 prepared in Example 2 of the present invention;

[0033] Figure 6 is a voltage-transmittance curve of the reverse electric-controlled dimming film A2 prepared in Example 2 of the present invention;

[0034] Figure 7 is a graph showing the cyclic stability of voltage-transmittance of the reverse electric-controlled dimming film A2 prepared in Example 2 of the present invention;

[0035] Figure 8 1 is a graph showing the cyclic stability of voltage-transmittance of the reverse electric-controlled dimming film D2 prepared in Comparative Example 2 of the present invention;

[0036] Fig. 9 is a scanning electron microscope image of the microscopic morphology of the polymer network in the reverse electrically controlled dimming film A3 prepared in Example 3 of the present invention;

[0037] Fig.10 is a voltage-transmittance curve of the reverse electric-controlled dimming film A3 prepared in Example 3 of the present invention;

[0038] Fig.11 3 is a graph showing the cyclic stability of voltage-transmittance of the reverse electric-controlled dimming film A3 prepared in Example 3 of the present invention;

[0039] Fig.12 3 is a graph showing the cyclic stability of voltage-transmittance of the reverse electrically controlled dimming film D2 prepared in comparative example 3 of the present invention. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that all raw materials in the embodiments of the present invention can be purchased on the market or prepared according to conventional methods known to those skilled in the art; "first" and "second" in the embodiments of the present invention are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; the groups in the embodiments of the present invention should be understood as the general meaning in the chemical field, for example: groups usually refer to atomic groups, including all "functional groups" in the structure of organic matter, specifically including hydrogen, fluorine, chlorine, bromine, iodine, alkyl, alkenyl, alkynyl, methoxy, phenyl, acyl, carboxyl, carbonyl, nitro, hydroxyl, sulfonic acid, etc. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0042] It should be noted that, in the embodiment of the present invention, Toff It indicates the light transmittance of the reverse electric control dimming film when no electric field is applied (off-state transmittance); T on It indicates the light transmittance (on-state transmittance) of the reverse electric control dimming film when an electric field of 100V is applied; V th Indicates the threshold voltage, which refers to when the light transmittance of the electrically controlled dimming film reaches T off The voltage required for 90% of sat Indicates the saturation voltage, which means when the light transmittance of the electronically controlled dimming film reaches T off The voltage required to achieve 10% of the required value; CR represents the contrast ratio, which is calculated as follows: CR = T off / T on ;t on Indicates the rise time, when the external electric field is applied, the transmittance reaches 10% T off The time required; t off It indicates the fall time, which refers to the time when the transmittance of the electrically controlled dimming film drops to 90% after the electric field is removed. off time.

[0043] Before explaining the embodiments of the present invention in detail, the technical problems addressed by the embodiments of the present invention and the corresponding technical principles are first explained.

[0044] In the prior art, due to the low polymer monomer content (about 5wt%) in the trans-PSLC electrically controlled dimming film, the polymer network is relatively thin, and it is easy to destroy the polymer network after a long period of cyclic power supply, which seriously affects the stability of the electro-optical performance of the trans-PSLC electrically controlled dimming film. However, if a dense polymer network is obtained by simply increasing the polymer monomer content, the driving voltage will inevitably be greatly increased, which will seriously affect the electro-optical performance of the trans-PSLC electrically controlled dimming film. The inventors unexpectedly discovered in the research of the trans-PSLC electrically controlled dimming film that by using 10-40 parts by weight of ultraviolet light photopolymerizable monomers, 60-90 parts by weight of liquid crystals, and an appropriate amount of ultraviolet light initiators and salt ions as raw materials, and preparing a polymer liquid crystal film between the first transparent conductive film and the second transparent conductive film through a photomask, the ultraviolet light photopolymerizable monomers can be caused to aggregate in the area not covered by the photomask to form a polymer wall network structure, so that the polymer network is more compact due to the increase in the content of ultraviolet light photopolymerizable monomers, and the polymer network will no longer easily break when the power is turned on and off many times, and the driving voltage will not rise significantly, which can better resist the damage caused by the cyclic power-on, and realize the improvement of the electro-optical performance stability of the trans-electrically controlled dimming film during cyclic use. In view of this, the trans-electrically controlled dimming film provided by the embodiment of the present invention has the advantages of high polymer monomer content and excellent electro-optical performance stability.

[0045] The embodiment of the present invention provides a transverse electrically controlled dimming film, which includes a first transparent conductive film, a second transparent conductive film and a polymer liquid crystal film, wherein the polymer liquid crystal film is composited between the first transparent conductive film and the second transparent conductive film to form a layered structure;

[0046] The polymer liquid crystal film is prepared using a photomask, and its component raw materials include:

[0047] UV-polymerizable monomer, used in an amount of 10-40 parts by weight;

[0048] Liquid crystal, the amount of which is 60-90 parts by weight;

[0049] an ultraviolet light initiator, the amount of which is 0.1-5% of the total weight of the ultraviolet light polymerizable monomer and the liquid crystal; and

[0050] The mass ratio of the salt ion to the ultraviolet light polymerizable monomer is 1:1-100.

[0051] The trans-electrically controlled dimming film provided by the embodiment of the present invention uses 10-40 parts by weight of ultraviolet light polymerizable monomers, 60-90 parts by weight of liquid crystals, and an appropriate amount of ultraviolet light initiator and salt ions as raw materials, and prepares a polymer liquid crystal film that can be composited between a first transparent conductive film and a second transparent conductive film through a photomask, which can promote the ultraviolet light photopolymerizable monomers to aggregate in the area not covered by the photomask to form a polymer wall network structure, so that the polymer network is more compact due to the increase in the content of ultraviolet light photopolymerizable monomers, and the polymer network will no longer break due to too low a polymer monomer content, so that it can better resist the damage caused by cyclic power-on, and achieve the improvement of the stability of the electro-optical performance of the trans-electrically controlled dimming film during cyclic use.

[0052] It should be noted that the first transparent conductive film and the second transparent conductive film are conductive layers of the reverse electrically controlled dimming film. The embodiment of the present invention does not impose any special restrictions on the specific material and thickness thereof, so as to obtain a reverse electrically controlled dimming film that can meet the photoelectric requirements. Specifically, the first transparent conductive film and the second transparent conductive film in the embodiment of the present invention are preferably made of the same material and thickness, and the material is preferably indium tin oxide, and the thickness is preferably 5-20 μm. A composite polymer liquid crystal film is used between the first transparent conductive film and the second transparent conductive film, and the thickness of the polymer liquid crystal film is preferably 1-100 μm.

[0053] It should be noted that the ultraviolet light polymerizable monomer in the embodiment of the present invention is preferably a combination of an acrylate having a first group and an acrylate having a second group, and the first group is the same as or different from the second group. Wherein, when the first group is different from the second group, the weight ratio of the acrylate having the first group to the acrylate having the second group is 1-3:1-3. Specifically, the acrylate having the first group is preferably 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate); the acrylate having the second group is preferably 4-cyanophenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate, 4-methoxyphenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate, 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)-2-fluorobenzoate), 4-((4-( any one of 3-(acryloyloxy)propoxy)benzoyl)oxy)-2-methylphenyl 4-(3-(buta-1,3-dien-2-yloxy)propoxy)benzoate, 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate), 2-methyl-1,4-phenylenebis(4-(4-(vinyloxy)butoxy)benzoate), and 4-((4-((6-(acryloyloxy)hexyl)oxy)benzoyl)oxy)phenyl 4-(hexyloxy)benzoate.

[0054] It should be noted that the liquid crystal in the embodiment of the present invention is preferably a negative nematic phase liquid crystal, and the crystallization point of the negative nematic phase liquid crystal is less than -40°C, the clearing point is greater than 100°C, the birefringence is greater than 0.1, the dielectric anisotropy is less than -0.5, and the viscosity is less than 200mP.s.

[0055] It should be noted that the salt ion in the embodiment of the present invention is preferably at least one of hexadecyltrimethylammonium bromide, tetrabutylamine perchlorate and 2,3,5,6-tetracyanoquinone.

[0056] It should be noted that the photoinitiator in the embodiment of the present invention is preferably at least one of benzoin ethyl ether, benzophenone, thioanthrone, benzil dimethyl ketal, 2-hydroxy-2-methyl-1-phenylacetone, trimethylbenzoyl diphenyl phosphine oxide, and benzoin diethyl ether.

[0057] The embodiment of the present invention further provides a method for preparing a reverse electrically controlled dimming film, comprising the following steps:

[0058] Mixing ultraviolet light polymerizable monomers, salt ions, liquid crystals and ultraviolet light initiators and pouring them into a liquid crystal box, wherein the inner surfaces of two conductive glasses of the liquid crystal box are respectively coated with a first transparent conductive film and a second transparent conductive film;

[0059] The liquid crystal box is covered with a photomask and subjected to ultraviolet curing to obtain a reverse electrically controlled dimming film.

[0060] It should be noted that the temperature for UV curing in the embodiment of the present invention is preferably 0-80°C, the time is preferably 1-30 min, and the light intensity is 0.1-30 mW / cm 2 .

[0061] It should be noted that the liquid crystal cell in the embodiment of the present invention is made of two pieces of conductive glass plated with indium tin oxide, with a thickness of 5-20 μm.

[0062] It should be noted that the substrate of the photomask in the embodiment of the present invention is preferably a polyester film or quartz glass, and has a circular or square shape; when the shape is circular, the circular area size is 50-500 μm.

[0063] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0064] Example 1

[0065] Embodiment 1 provides a method for preparing a reverse electrically controlled dimming film A1, comprising the following steps S101 to S102.

[0066] S101: Mix the UV-polymerizable monomers (C6M and HCM-020), salt ions CTAB, liquid crystal GXV-7822-180 and UV-initiator Irg651 in the mass fraction ratios in Table 1 according to the amounts described in Table 1, and after being fully stirred, pour them into a liquid crystal box made of two pieces of conductive glass with indium tin oxide coated on the inner side, so that the liquid crystal molecules are vertically oriented, and the thickness of the liquid crystal box is controlled at 8.0 μm.

[0067] Table 1 - Raw material components and dosage of Example 1

[0068]

[0069] Among them, the birefringence of liquid crystal GXV-7822-180 is 0.180, the crystallization point is less than -40°C, the clearing point is 107°C, the viscosity is 67mP.s, and the dielectric anisotropy is -4.4; the UV-polymerizable monomer C6M is 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate); the UV-polymerizable monomer HCM-020 is 4-cyanophenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate; the salt ion CTAB is hexadecyltrimethylammonium bromide; and the UV-light initiator Irg651 is benzoin diethyl ether.

[0070] S102: After covering the liquid crystal box prepared in step S101 with a photomask,2 The UV curing was performed for 600 seconds under the UV intensity of , and a reverse electrically controlled dimming film with a polymer wall structure was obtained, namely, the reverse electrically controlled dimming film A1. The coverage size of the photomask was 300 μm.

[0071] Comparative Example 1

[0072] Comparative Example 1 provides a method for preparing a reverse electrically controlled dimming film D1, including the following steps S101 to S102.

[0073] S101: Mix the UV polymerizable monomers (C6M and HCM-020), salt ions CTAB, liquid crystal GXV-7822-180 and UV initiator Irg651 in the same amounts as described in Table 1 according to the mass fraction ratio in Table 1, and after fully stirring, pour them into a liquid crystal box made of two pieces of conductive glass with indium tin oxide coated on the inner side. The thickness of the liquid crystal box is controlled to 8.0 μm.

[0074] Among them, the UV-polymerizable monomer C6M is 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate); the UV-polymerizable monomer HCM-020 is 4-cyanophenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate; the salt ion CTAB is hexadecyltrimethylammonium bromide; and the UV-initiator Irg651 is benzoin diethyl ether.

[0075] S102: The liquid crystal box prepared in step S101 is heated at 25°C and 0.8 mW / cm 2 The film was directly UV-cured for 600 seconds under a UV intensity of , to obtain a trans-type electrically-controlled dimming film without a polymer wall structure, namely, the trans-type electrically-controlled dimming film D1.

[0076] The reverse electric dimming film A1 prepared in Example 1 and the reverse electric dimming film D1 prepared in Comparative Example 1 were characterized, and the results are as follows:

[0077] 1.1 Scanning electron microscopy: The sample of the reverse electric control dimming film A1 prepared in Example 1 was cut into small pieces. To avoid the presence of liquid crystal affecting the observation of the polymer network, the sample was immersed in cyclohexane to remove the liquid crystal. The sample was then sprayed with gold and observed under a scanning electron microscope. The scanning electron microscope image obtained is as follows: Figure 1 shown.

[0078] according to Figure 1 It can be seen that most of the UV-polymerizable monomers form a relatively dense polymer network in the area not covered by the photomask, and there is very little polymer network in the area covered by the mask.

[0079] 1.2 Liquid crystal comprehensive parameter test: The reverse electric control dimming film A1 prepared in Example 1 was tested by a liquid crystal comprehensive parameter tester LCT-5066C, and the voltage-transmittance curve obtained was as follows: Figure 2 shown.

[0080] according to Figure 2 It can be seen that the threshold voltage (V th ) is 5.51176V, and the saturation voltage (V sat ) is 22.458V, the on-state response time (t on ) is 1.3ms, and the off-state response time (t off ) is 18.6ms and the contrast ratio (CR) is 9.45.

[0081] 1.3 Cyclic stability test of on-off transmittance and response time: Take the transverse electrically controlled dimming film A1 prepared in Example 1 and the transverse electrically controlled dimming film D1 prepared in Comparative Example 1, and use the liquid crystal comprehensive parameter tester LCT-5066C to cycle on and off 0, 1000, 3000, 5000, 10000, 150000 times and test, and obtain the on-state transmittance T on , Off-state transmittance T off , Open state response time t on , Off-state response time t off The cyclic stability of Figure 3 to Figure 4 As shown. Among them, Figure 3 The figure shows the cycle stability result of voltage-transmittance of the reverse electric control dimming film A1 prepared in Example 1; Figure 4 The graph shows the voltage-transmittance cycle stability result of the reverse electric-controlled dimming film D1 prepared in Comparative Example 1.

[0082] Will Figure 3 and Figure 4 By comparison, it can be clearly seen that the cyclic stability of the electro-optical performance of the trans-electrically controlled dimming film A1 prepared in Example 1 is significantly better than that of the trans-electrically controlled dimming film D1 prepared in Comparative Example 1, indicating that the present invention uses a photomask to prepare a polymer liquid crystal film that can be composited between a first transparent conductive film and a second transparent conductive film, which can promote the aggregation of ultraviolet light-polymerizable monomers in the area not covered by the photomask to form a polymer wall network structure, thereby making the polymer network more compact due to the increase in the content of ultraviolet light-polymerizable monomers, and the polymer network will no longer break easily, and the driving voltage will not increase significantly, which can better resist the damage caused by cyclic power-on, thereby achieving the improvement of the stability of the electro-optical performance of the trans-electrically controlled dimming film in cyclic use.

[0083] Example 2

[0084] Embodiment 2 provides a method for preparing a reverse electrically controlled dimming film A2, comprising the following steps S101 to S102.

[0085] S101: Mix the UV polymerizable monomers (C6M and HCM-020), salt ions CTAB, liquid crystal GXV-7822-180 and UV initiator Irg651 in the amounts described in Table 2 according to the mass fraction ratio in Table 2, and after fully stirring, pour them into a liquid crystal box made of two pieces of conductive glass with indium tin oxide coated on the inner side. The thickness of the liquid crystal box is controlled to 8.0 μm.

[0086] Table 2 - Raw material components and dosage of Example 2

[0087]

[0088]

[0089] Among them, the birefringence of liquid crystal GXV-7822-180 is 0.180, the crystallization point is less than -40°C, the clearing point is 107°C, the viscosity is 67mP.s, and the dielectric anisotropy is -4.4; the UV-polymerizable monomer C6M is 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate); the UV-polymerizable monomer HCM-020 is 4-cyanophenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate; the salt ion CTAB is hexadecyltrimethylammonium bromide; and the UV-light initiator Irg651 is benzoin diethyl ether.

[0090] S102: After covering the liquid crystal box prepared in step S101 with a photomask, 2 The UV curing was performed for 600 seconds under the UV intensity of , and a reverse electrically controlled dimming film with a polymer wall structure was obtained, namely, the reverse electrically controlled dimming film A1. The coverage size of the photomask was 300 μm.

[0091] Comparative Example 2

[0092] Comparative Example 2 provides a method for preparing a reverse electrically controlled dimming film D2, including the following steps S101 to S102.

[0093] S101: Mix the UV polymerizable monomers (C6M and HCM-020), salt ions CTAB, liquid crystal GXV-7822-180 and UV initiator Irg651 in the same amounts as those in Table 2 according to the mass fraction ratios in Table 2, and after being fully stirred, pour them into a liquid crystal box made of two pieces of conductive glass with indium tin oxide plated on the inner side. The thickness of the liquid crystal box is controlled to be 8.0 μm.

[0094] Among them, the UV-polymerizable monomer C6M is 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate); the UV-polymerizable monomer HCM-020 is 4-cyanophenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate; the salt ion CTAB is hexadecyltrimethylammonium bromide; and the UV-initiator Irg651 is benzoin diethyl ether.

[0095] S102: The liquid crystal box prepared in step S101 is heated at 25°C and 0.8 mW / cm 2 The film was directly UV-cured for 600 seconds under a UV intensity of , to obtain a trans-type electrically-controlled dimming film without a polymer wall structure, namely, the trans-type electrically-controlled dimming film D2.

[0096] The reverse electrically controlled dimming film A2 prepared in Example 2 and the reverse electrically controlled dimming film D2 prepared in Comparative Example 2 were characterized, and the results are as follows:

[0097] 2.1 Scanning electron microscopy: The sample of the reverse electric control dimming film A2 prepared in Example 2 was cut into small pieces. To avoid the presence of liquid crystal affecting the observation of the polymer network, the sample was immersed in cyclohexane to remove the liquid crystal. The sample was then sprayed with gold and observed under a scanning electron microscope. The scanning electron microscope image obtained is as follows: Figure 5 shown.

[0098] according to Figure 5 It can be seen that: when the total content of UV-polymerizable monomers is 20%, most of the UV-polymerizable monomers gather in the area not covered by the mask to form a dense polymer wall structure, while the polymer network in the mask-covered area is relatively sparse and the polymer network mesh size is larger.

[0099] 2.2 Liquid crystal comprehensive parameter test: The reverse electric control dimming film A2 prepared in Example 2 was tested by a liquid crystal comprehensive parameter tester LCT-5066C, and the voltage-transmittance curve obtained was as shown in FIG. Figure 6 shown.

[0100] according to Figure 6 It can be seen that the threshold voltage (V th ) is 20.4652V, and the saturation voltage (V sat ) is 46.3842V, the on-state response time (t on ) is 2ms, the off-state response time (t off ) is 2.8ms and the contrast ratio (CR) is 55.

[0101] 2.3 Cyclic stability test of on-off transmittance and response time: The transverse electrically controlled dimming film A2 prepared in Example 2 and the transverse electrically controlled dimming film D2 prepared in Comparative Example 2 were tested by a liquid crystal comprehensive parameter tester LCT-5066C for 0, 1000, 3000, 5000, 10000, and 150000 cycles of power on and off to obtain their on-state transmittance T on , Off-state transmittance T off , Open state response time t on , Off-state response time t off The cyclic stability of Figures 7 and 8 As shown. Among them, Figure 7 The figure shows the cycle stability result of voltage-transmittance of the reverse electric control dimming film A2 prepared in Example 2; Figure 8 The graph shows the voltage-transmittance cycle stability result of the reverse electric-controlled dimming film D2 prepared in Comparative Example 2.

[0102] Will Figure 7 and Figure 8 By comparison, it can be clearly seen that the cyclic stability of the electro-optical performance of the trans-electrically controlled dimming film A2 prepared in Example 2 is significantly better than that of the trans-electrically controlled dimming film D2 prepared in Comparative Example 2, indicating that the present invention prepares a polymer liquid crystal film that can be composited between a first transparent conductive film and a second transparent conductive film through a photomask, which can promote the aggregation of ultraviolet light-polymerizable monomers in the area not covered by the photomask to form a polymer wall network structure, thereby making the polymer network more compact due to the increase in the content of ultraviolet light-polymerizable monomers, and the polymer network will no longer break easily, and the driving voltage will not increase significantly, which can better resist the damage caused by cyclic power-on, thereby achieving the improvement of the electro-optical performance stability of the trans-electrically controlled dimming film in cyclic use.

[0103] Example 3

[0104] Embodiment 3 provides a method for preparing a reverse electrically controlled dimming film A3, comprising the following steps S101 to S102.

[0105] S101: Mix the UV-polymerizable monomers (C6M and HCM-021), salt ions CTAB, liquid crystal GXV-7822-180 and UV-initiator Irg651 in the mass fraction ratios in Table 3 according to the amounts described in Table 3, and after being fully stirred, pour them into a liquid crystal box made of two pieces of conductive glass with indium tin oxide coated on the inner side. The thickness of the liquid crystal box is controlled to be 8.0 μm.

[0106] Table 3 - Raw material components and dosage of Example 3

[0107]

[0108] Among them, the birefringence of liquid crystal GXV-7822-180 is 0.180, the crystallization point is less than -40°C, the clearing point is 107°C, the viscosity is 67mP.s, and the dielectric anisotropy is -4.4; the UV-polymerizable monomer C6M is 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate); the UV-polymerizable monomer HCM-021 is 4-methoxyphenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate; the salt ion CTAB is hexadecyltrimethylammonium bromide; and the UV-light initiator Irg651 is benzoin diethyl ether.

[0109] S102: After covering the liquid crystal box prepared in step S101 with a photomask, 2 The UV curing was performed for 600 seconds under the UV intensity of , and a reverse electrically controlled dimming film with a polymer wall structure was obtained, namely, the reverse electrically controlled dimming film A3. The covering size of the photomask was 300 μm.

[0110] Comparative Example 3

[0111] Comparative Example 3 provides a method for preparing a reverse electrically controlled dimming film D3, including the following steps S101 to S102.

[0112] S101: Mix the UV-polymerizable monomers (C6M and HCM-021), salt ions CTAB, liquid crystal GXV-7822-180 and UV-initiator Irg651 in the same amounts as those in Table 3 according to the mass fraction ratios in Table 3, and after being fully stirred, pour them into a liquid crystal box made of two pieces of conductive glass with indium tin oxide coated on the inner side. The thickness of the liquid crystal box is controlled to be 8.0 μm.

[0113] Among them, the UV-polymerizable monomer C6M is 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate); the UV-polymerizable monomer HCM-021 is 4-methoxyphenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate; the salt ion CTAB is hexadecyltrimethylammonium bromide; and the UV-light initiator Irg651 is benzoin diethyl ether.

[0114] S102: The liquid crystal box prepared in step S101 is heated at 25°C and 0.8 mW / cm 2 The film was directly UV-cured for 600 s at a UV intensity of , to obtain a trans-type electrically-controlled dimming film without a polymer wall structure, namely, the trans-type electrically-controlled dimming film D3.

[0115] The reverse electrically controlled dimming film A3 prepared in Example 3 and the reverse electrically controlled dimming film D3 prepared in Comparative Example 3 were characterized, and the results are as follows:

[0116] 3.1 Scanning electron microscopy: The sample of the reverse electric control dimming film A3 prepared in Example 3 was cut into small pieces. To avoid the presence of liquid crystal affecting the observation of the polymer network, the sample was immersed in cyclohexane to remove the liquid crystal. The sample was then sprayed with gold and observed under a scanning electron microscope. The scanning electron microscope image obtained is as follows: Fig. 9 shown.

[0117] according to Fig. 9 It can be seen that most of the UV-polymerizable monomers form a denser polymer network in the area not covered by the photomask, and there are fewer polymer networks in the area covered by the mask, and the size of the polymer mesh is large.

[0118] 3.2 Liquid crystal comprehensive parameter test: The reverse electric control dimming film A3 prepared in Example 3 was tested by a liquid crystal comprehensive parameter tester LCT-5066C. The voltage-transmittance curve obtained is as follows: Fig.10 shown.

[0119] according to Fig.10 It can be seen that the threshold voltage (V th ) is 11.4958V, and the saturation voltage (V sat ) is 24.4516V, the on-state response time (t on ) is 1.7ms, and the off-state response time (t off ) is 1.1ms and the contrast ratio (CR) is 28.98.

[0120] 3.3 Cyclic stability test of on-off transmittance and response time: The trans-electrically controlled dimming film A3 prepared in Example 3 and the trans-electrically controlled dimming film D3 prepared in Comparative Example 3 were tested by a liquid crystal comprehensive parameter tester LCT-5066C for 0, 1000, 3000, 5000, 10000, and 150000 cycles of power on and off to obtain their on-state transmittance T on , Off-state transmittance T off , Open state response time t on , Off-state response time t off The cyclic stability of Figures 7 and 8 As shown. Among them, Fig.11 The figure shows the cycle stability result of voltage-transmittance of the reverse electric control dimming film A3 prepared in Example 3; Fig.12 The graph shows the voltage-transmittance cycle stability result of the reverse electric-controlled dimming film D3 prepared in comparative example 3.

[0121] Will Fig.11 and Fig.12By comparison, it can be clearly seen that the cyclic stability of the electro-optical performance of the trans-electrically controlled dimming film A3 prepared in Example 3 is significantly better than that of the trans-electrically controlled dimming film D3 prepared in Comparative Example 3, indicating that the present invention prepares a polymer liquid crystal film that can be composited between a first transparent conductive film and a second transparent conductive film through a photomask, which can promote the aggregation of ultraviolet light-polymerizable monomers in the area not covered by the photomask to form a polymer wall network structure, thereby making the polymer network more compact due to the increase in the content of ultraviolet light-polymerizable monomers, and the polymer network will no longer break easily, and the driving voltage will not increase significantly, which can better resist the damage caused by cyclic power-on, thereby achieving the improvement of the electro-optical performance stability of the trans-electrically controlled dimming film in cyclic use.

[0122] In summary, an embodiment of the present invention provides a trans-electrically controlled dimming film, which uses 10-40 parts by weight of ultraviolet light polymerizable monomers, 60-90 parts by weight of liquid crystals, and an appropriate amount of photoinitiators and salt ions as raw materials, and prepares a polymer liquid crystal film that can be composited between a first transparent conductive film and a second transparent conductive film through a photomask, which can promote the ultraviolet light photopolymerizable monomers to aggregate in the area not covered by the photomask to form a polymer wall network structure, so that the polymer network is more compact due to the increase in the content of ultraviolet light photopolymerizable monomers to more than 10wt%, and can better resist the damage caused by cyclic power-on, thereby achieving an improvement in the stability of the electro-optical performance of the trans-electrically controlled dimming film during cyclic use, and obtaining a trans-electrically controlled dimming film with a high monomer content and excellent electro-optical performance cyclic stability.

[0123] Comparing Example 1, Example 2, and Example 3, the content of ultraviolet polymerizable monomer in the reverse electric control dimming film A2 is the highest. At the same time, the electro-optical performance is better than that of the reverse electric control dimming film A1 and the reverse electric control dimming film A3, and the improvement effect of the stability of the electro-optical performance is the most obvious. Comparing Comparative Example 1, Comparative Example 2, and Comparative Example 3, after 150,000 cycles of power on and off, the off-state transmittance of the reverse electric control dimming film D1 decreased by 7.3%, the on-state transmittance increased by 65.5%, and the contrast decreased by 44%; after 150,000 cycles of power on and off, the off-state transmittance of the reverse electric control dimming film D2 decreased by 12%, the on-state transmittance increased by 152%, and the contrast decreased by 66%; after 150,000 cycles of power on and off, the off-state transmittance of the reverse electric control dimming film D3 decreased by 7.3%, the on-state transmittance increased by 135%, and the contrast decreased by 59%.

[0124] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0125] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A reverse electric control dimming film, characterized in that: The invention comprises a first transparent conductive film, a second transparent conductive film and a polymer liquid crystal film, wherein the polymer liquid crystal film is composited between the first transparent conductive film and the second transparent conductive film to form a layered structure; wherein the polymer liquid crystal film is prepared using a circular photomask with a diameter of 300-500 μm, and the composition of the component raw materials is as follows: Ultraviolet light polymerizable monomer, used in an amount of 10 parts by weight; Negative nematic liquid crystal, the amount of which is 90 parts by weight; an ultraviolet light initiator, the amount of which is 0.5 wt % of the total weight of the ultraviolet light polymerizable monomer and the negative nematic liquid crystal; and Salt ions, wherein the mass ratio of the salt ions to the ultraviolet light polymerizable monomer is 1:100; The ultraviolet light polymerizable monomer is composed of an acrylate having a first group and an acrylate having a second group in a weight ratio of 5:5, and the first group is different from the second group; The acrylic acid ester having the first group is 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate); The acrylate having the second group is any one of 4-cyanophenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate and 4-methoxyphenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate; The ultraviolet light polymerizable monomer forms a polymer wall network structure in the area not covered by the photomask, making the polymer network more compact and less likely to break, thereby improving the cyclic power-on stability of the reverse electrically controlled dimming film; The negative nematic liquid crystal has a crystallization point of less than -40°C, a clearing point greater than 100°C, a birefringence greater than 0.1, a dielectric anisotropy less than -0.5, and a viscosity less than 200 mP.s.

2. The reverse electric control dimming film according to claim 1, characterized in that: The salt ion is selected from at least one of hexadecyltrimethylammonium bromide, tetrabutylamine perchlorate and 2,3,5,6-tetracyanoquinone.

3. The reverse electric control dimming film according to claim 1, characterized in that: The ultraviolet light initiator is selected from at least one of benzoin ethyl ether, benzophenone, thioanthrone, benzil dimethyl ketal, 2-hydroxy-2-methyl-1-phenylacetone, trimethylbenzoyl diphenyl phosphine oxide, and benzoin diethyl ether.

4. A method for preparing the reverse electric control dimming film according to any one of claims 1 to 3, characterized in that: The following steps are involved: The ultraviolet light polymerizable monomer, salt ions, liquid crystal and ultraviolet light initiator are mixed and poured into a liquid crystal box to make the liquid crystal molecules vertically oriented, wherein the inner surfaces of the two substrates of the liquid crystal box are respectively coated with a first transparent conductive film and a second transparent conductive film; the liquid crystal box is covered with a photomask and ultraviolet curing is performed to obtain the reverse electrically controlled dimming film.

5. The method for preparing the reverse electric-controlled dimming film according to claim 4, characterized in that: The UV curing temperature is 0-80°C, the time is 1-30min, and the light intensity is 0.1-30mW / cm 2 .

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