Method for manufacturing electrochromic members with transparency and stretchability on poly(butyl acrylate) substrates

Abstract

The present invention relates to a composition for an electrochromic device having transparency and elasticity based on poly(butyl acrylate) and a method for producing an electrochromic member. The composition for an electrochromic device according to an embodiment of the present invention includes a light-transmitting polymer resin, a cross-linking agent, an initiator, an ionic liquid, and an electrochromic material, and the light-transmitting polymer resin is poly(butyl acrylate).

Description

[Technical Field]

[0001] The present invention relates to a composition for an electrochromic element having transparency and flexibility based on poly(butyl acrylate), and a method for producing the electrochromic member. [Background technology]

[0002] An electrochromic element contains an electrochromic material and changes color depending on the voltage applied from the outside. Various materials such as polymer compounds and metal oxides are used as the electrochromic material, and the color changes reversibly depending on the voltage applied to the electrodes.

[0003] Recently, the application of such color-changing elements has been expanding, including smart window systems that block outside views and sunlight, and automotive glass that displays information such as maps and text.

[0004] Conventional electrochromic elements use liquid electrochromic materials, which can cause electrolyte leakage, limiting their use in flexible displays.Recently, solidified water-based electrolytes have been developed, but they require an additional protective layer to prevent water from evaporating. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent Registration No. 10-2078481 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a composition for an electrochromic element having optical transparency and stretchability, and a method for producing an electrochromic member.

[0007] Also, various electrochromic materials can be used to realize various colors.

[0008] In addition, the film is moisture-resistant and flexible, making it applicable to a variety of fields.

[0009] Furthermore, the manufacturing method is simple, which allows for increased production efficiency and reduced manufacturing costs. [Means for solving the problem]

[0010] The composition for an electrochromic device according to an embodiment of the present invention includes a light-transmitting polymer resin, a crosslinking agent, an initiator, an ionic liquid, and an electrochromic material, and the light-transmitting polymer resin is poly(butyl acrylate).

[0011] The cross-linking agent may be polyethylene glycol dimethacrylate, and the content of the cross-linking agent may be 1 to 2 parts by weight based on 100 parts by weight of the light-transmitting polymer resin.

[0012] The initiator may be 1-hydroxycyclohexyl phenyl ketone, and the content of the initiator may be 0.5 to 2 parts by weight based on 100 parts by weight of the light-transmitting polymer resin.

[0013] The ionic liquid may be 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and the content of the ionic liquid may be 150 to 250 parts by weight based on 100 parts by weight of the light-transmitting polymer resin.

[0014] The anode redox compound may further be included in an amount of 1 to 8 parts by weight based on 100 parts by weight of the polymer resin.

[0015] The color-changing material may be MHV, and the content of the color-changing material may be 8 to 15 parts by weight based on 100 parts by weight of the light-transmitting polymer resin.

[0016] The color-changing material may be DHV, and the content of the color-changing material may be 10 to 20 parts by weight based on 100 parts by weight of the light-transmitting polymer resin.

[0017] The color-changing material may be TFMFPhV, and the content of the color-changing material may be 1 to 10 parts by weight based on 100 parts by weight of the light-transmitting polymer resin.

[0018] An electrochromic element according to an embodiment of the present invention includes a first electrode, a second electrode, and an electrochromic element layer that changes color in response to a voltage applied between the first electrode and the second electrode, and the electrochromic element layer includes the composition for an electrochromic element described above.

[0019] A method for manufacturing an electrochromic member according to an embodiment of the present invention includes a step of mixing a light-transmitting polymer resin, a crosslinking agent, an initiator, an ionic liquid, and an electrochromic material to prepare a mixture.

[0020] In the step of preparing the mixture, the content of the crosslinker may be 1 to 2 parts by weight, the content of the initiator may be 0.5 to 2 parts by weight, and the content of the ionic liquid may be 150 to 250 parts by weight, relative to 100 parts by weight of the polymer resin. [Effects of the Invention]

[0021] The composition for an electrochromic element and the method for manufacturing an electrochromic member according to the embodiments of the present invention may have optical transparency and flexibility.

[0022] Also, various electrochromic materials can be used to realize various colors.

[0023] In addition, the film is moisture-resistant and flexible, making it applicable to a variety of fields.

[0024] Furthermore, the manufacturing method is simple, which allows for increased production efficiency and reduced manufacturing costs. [Brief explanation of the drawings]

[0025] [Figure 1] 1 shows the results of evaporation tests on ion gels 1 to 6. [Figure 2]1 shows the results of tensile strength-strain measurements for ion gels 1 to 6. [Figure 3] FIG. 10 is a Nyquist diagram showing the results of an impedance experiment. [Figure 4] FIG. 1 is a diagram showing the results of measurements by cyclic voltammetry. [Figure 5] FIG. 1 is a diagram showing the results of measurements by cyclic voltammetry. [Figure 6] FIG. 1 is a diagram showing the results of measurements by cyclic voltammetry. [Figure 7] FIG. 10 is a diagram showing the measurement results of light absorptance. [Figure 8] FIG. 10 is a diagram showing the measurement results of light absorptance. [Figure 9] FIG. 10 is a diagram showing the measurement results of light absorptance. [Figure 10] Photographs showing the results of bleaching and coloring experiments. [Figure 11] Photographs showing the results of bleaching and coloring experiments. [Figure 12] Photographs showing the results of bleaching and coloring experiments. [Figure 13] FIG. 10 is a diagram showing the measurement results of light transmittance. [Figure 14] FIG. 10 is a diagram showing the measurement results of light transmittance. [Figure 15] FIG. 10 is a diagram showing the measurement results of light transmittance. [Figure 16] FIG. 1 shows optical density versus charge density analysis. [Figure 17] FIG. 1 shows optical density versus charge density analysis. [Figure 18] FIG. 1 shows optical density versus charge density analysis. DETAILED DESCRIPTION OF THE INVENTION

[0026] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Therefore, the shapes and sizes of elements in the drawings may be exaggerated for clarity, and elements denoted by the same reference numerals in the drawings are the same elements. Furthermore, the same reference numerals are used throughout the drawings for parts having similar functions and actions. Furthermore, throughout the specification, the term "comprising" a certain element does not mean excluding other elements, but means that the term may further include other elements, unless otherwise specified.

[0027] Composition for electrochromic elements The composition for an electrochromic device according to an embodiment of the present invention includes a light-transmitting polymer resin, a crosslinking agent, an initiator, an ionic liquid, and an electrochromic material, and the light-transmitting polymer resin is poly(butyl acrylate).

[0028] By using poly(butyl acrylate) (PBA) as the main polymer, the film can have optical transparency, flexibility, and stretchability. In particular, by using it together with the crosslinking agent, initiator, and ionic liquid used in the embodiments of the present invention, these properties can be further improved. The molecular formula of the poly(butyl acrylate) is (CH 12 O2) n (n is a natural number) and its chemical formula is as shown in Chemical Formula 1 below. The molecular weight of the poly(butyl acrylate) is not particularly limited, but may be 20,000 to 100,000.

[0029] [ka]

[0030] The crosslinking agent functions to improve mechanical properties such as hardness and elasticity and to provide chemical stability by forming crosslinks between the chains of the light-transmitting polymer. The crosslinking agent is preferably polyethylene glycol dimethacrylate (PEGDA), which bonds with the light-transmitting polymer to provide elasticity and flexibility. The molecular formula of polyethylene glycol dimethacrylate is C3H5C(O)(OCH2CH2). n It is OC(O)C3H5 (n is a natural number), and the chemical formula can be the following Chemical Formula 2.

[0031] [ka]

[0032] The content of the crosslinking agent may be 1 to 2 parts by weight, preferably 1 to 1.4 parts by weight, based on 100 parts by weight of the light-transmitting polymer resin. If the content of the crosslinking agent is too high, light transmittance may decrease, and if the content of the crosslinking agent is too low, mechanical properties of the manufactured color-changing element member may decrease.

[0033] The initiator functions to initiate a polymerization reaction between the light-transmitting polymer and the crosslinking agent. The initiator may be 1-hydroxycyclohexyl phenyl ketone (PI). The molecular formula of 1-hydroxycyclohexyl phenyl ketone is HOC6H. 10 COC6H5, and its chemical formula can be represented by Chemical Formula 3 below.

[0034] [ka]

[0035] The content of the initiator may be 0.5 to 2 parts by weight, preferably 0.8 to 1.2 parts by weight, based on 100 parts by weight of the light-transmitting polymer resin. If the content of the initiator is too high, flexibility and stretchability may decrease, and if the content of the initiator is too low, strength may decrease.

[0036] Ionic liquids generally remain in a non-volatile state at 100°C and improve the movement of ions and electrons in the electrochromic material. The ionic liquid may be 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM TFSI). The molecular formula of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide is C 10 H 15 It is F6N3O4S2 and its chemical formula is shown in Chemical Formula 4 below.

[0037] [ka]

[0038] The content of the ionic liquid may be 150 to 250 parts by weight, preferably 180 to 220 parts by weight, based on 100 parts by weight of the light-transmitting polymer resin. If the content of the ionic liquid is too low, the ionic conductivity of the ion gel may decrease, and if the content is too high, the light transmittance may decrease.

[0039] In one embodiment, the composition for an electrochromic device may further include an anode redox compound. The anode redox compound may be one of ferrocene and dimethylferrocene, preferably dimethylferrocene. The dimethylferrocene may be represented by the following Formula 5:

[0040] [ka]

[0041] The content of the anode redox compound may be 1 to 8 parts by weight based on 100 parts by weight of the polymer resin.

[0042] An electrochromic material is a material that changes its color by changing the wavelength of absorption depending on an externally applied voltage. In the embodiments of the present invention, various electrochromic materials can be used depending on the color to be realized.

[0043] To realize red or magenta-based hues, the electrochromic material may be 1-heptyl-[4,4'-bipyridine](hexafluorophosphate) (MHV[PF6]), which may be represented by Chemical Formula 6.

[0044] [ka]

[0045] In this case, the content of the color-changing material may be 8 to 15 parts by weight, more preferably 13 to 15 parts by weight, based on 100 parts by weight of the light-transmitting polymer resin. If the content deviates from this range, problems such as poor color realization or reduced lifespan may occur.

[0046] To realize a blue or cyan color, the electrochromic material may be 1,1'-diheptyl-[4,4'-bipyridine]bis(hexafluorophosphate) (DHV[PF6]2), which may be represented by Chemical Formula 7.

[0047] [ka]

[0048] In this case, the content of the color-changing material may be 10 to 20 parts by weight, more preferably 16 to 18 parts by weight, based on 100 parts by weight of the light-transmitting polymer resin. If the content deviates from this range, problems such as poor color realization or reduced lifespan may occur.

[0049] To realize a green hue, the electrochromic material may be 3-fluoro-4-(trifluoromethyl)phenyl-[4,4'-bipyridine]hexafluorophosphate (TFMFPhV[PF6]2), which may be represented by Chemical Formula 8.

[0050] [ka]

[0051] In this case, the content of the color-changing material may be 1 to 10 parts by weight, more preferably 6 to 8 parts by weight, based on 100 parts by weight of the light-transmitting polymer resin. If the content deviates from this range, problems such as poor color realization or reduced lifespan may occur.

[0052] Electrochromic element An electrochromic element according to an embodiment of the present invention includes a first electrode, a second electrode, and an electrochromic element layer that changes color in response to a voltage applied between the first electrode and the second electrode, and the electrochromic element layer includes an electrochromic member manufactured using the composition for electrochromic elements described above.

[0053] The first and second electrodes may be any electrode commonly used in electrical devices, but may be made of ITO glass or ITO-PEN, which has optical transparency, flexibility, and stretchability.

[0054] The electrochromic element layer may contain the composition for electrochromic elements described above, and may be prepared in an appropriate size and thickness using the composition for electrochromic elements according to the preparation method described below.

[0055] Manufacturing method of electrochromic member A method for manufacturing an electrochromic member according to an embodiment of the present invention includes a step of mixing a light-transmitting polymer resin, a crosslinking agent, an initiator, an ionic liquid, and an electrochromic material to prepare a mixture.

[0056] The light-transmitting polymer resin, crosslinking agent, initiator, electrochromic material, and ionic liquid mixed in the step of preparing the mixture are the same as those described above.

[0057] In the step of preparing the mixture, the content of the crosslinker may be 1 to 2 parts by weight, the content of the initiator may be 0.5 to 2 parts by weight, and the content of the ionic liquid may be 150 to 250 parts by weight, relative to 100 parts by weight of the polymer resin.

[0058] In one embodiment, the method may include curing the mixture after the step of preparing the mixture, which may be performed by irradiating the mixture with UV light, preferably with a wavelength of 100 to 400 nm, for 2 to 30 minutes.

[0059] Manufacturing example: Manufacturing of PBA mixed ion gel Ion Gel 1 0.5g of PBA as a polymer resin, 0.006g of PEGDA as a crosslinking agent, and 0.005g of PI as an initiator were mixed and then photo-cured for 10 minutes in a UV curing oven at a wavelength of 365nm.

[0060] Ion Gel 2 The same procedure as for Ion Gel 1 was carried out except that 0.25 g of BMIM TFSI was further added.

[0061] Ion Gel 3 The same procedure as for Ion Gel 1 was carried out except that 0.5 g of BMIM TFSI was further added.

[0062] Ion Gel 4 The same procedure as for Ion Gel 1 was carried out except that 0.75 g of BMIM TFSI was further added.

[0063] Ion Gel 5 The same procedure as for Ion Gel 1 was carried out except that 1.0 g of BMIM TFSI was further added.

[0064] Ion Gel 6 The same procedure as in Ion Gel 1 was carried out except that 1.25 g of BMIM TFSI was further added.

[0065] Experimental example: Evaporation test Ion gels 1 to 6 were cut to a certain size and then weighed at room temperature (20-27°C) and 19-40% RH for 30 days. Figure 1 shows the results of this experiment. It can be seen from Figure 1 that the weight of the ion gels did not change even when the ionic liquid content increased.

[0066] Experimental example: Tensile strength-strain measurement Measurements were performed on ion gels 1 to 6 using a universal testing machine (UTM, Tinius Olsen, H5KT) in accordance with ASTM D638 type V. Figure 2 shows the experimental results. Referring to Figure 2, it can be seen that the tensile strength decreases as the content of ionic liquid increases. Ion gel 5 has the most suitable flexibility and stretchability, while ion gel 6 has too low tensile strength and easily tears, making it difficult to use as an electrochromic device. Therefore, it is determined that adding 200 parts by weight of ionic liquid to 100 parts by weight of light-transmitting polymer is most suitable for ion gel 5.

[0067] Experimental example: Measurement of ionic conductivity The electrochromic members prepared in the examples and comparative examples were placed between platinum electrodes, and the impedance spectra were measured using an impedance spectrometer. Figure 4 is a Nyquist diagram showing the experimental results.

[0068] Manufacturing example: Manufacturing electrochromic materials Example 1 0.5g of PBA as polymer resin, 0.006g of PEGDA as crosslinker, 0.005g of PI as initiator, 1g of BMIM TFSI as ionic liquid, 0.04g of MHV[PF6] as electrochromic material, and 0.022g of dimethylferrocene as anodic redox compound were mixed, and then photo-cured for 10 minutes in a UV curing oven at a wavelength of 365nm.

[0069] Example 2 The same procedure as in Example 1 was carried out, except that 0.05 g of MHV[PF6] and 0.029 g of dimethylferrocene were added.

[0070] Example 3 The same procedure as in Example 1 was carried out, except that 0.06 g of MHV[PF6] and 0.036 g of dimethylferrocene were added.

[0071] Example 4 The same procedure as in Example 1 was carried out, except that 20.06 g of DHV[PF6] and 0.022 g of dimethylferrocene were added instead of MHV[PF6].

[0072] Example 5 The same procedure as in Example 4 was carried out except that 20.07 g of DHV[PF6] and 0.027 g of dimethylferrocene were added.

[0073] Example 6 The same procedure as in Example 4 was carried out except that 20.086 g of DHV[PF6] and 0.0319 g of dimethylferrocene were added.

[0074] Example 7 The same procedure as in Example 1 was carried out, except that 20.00965 g of TFMFPhV[PF6] and 0.005352 g of dimethylferrocene were used instead of MHV[PF6].

[0075] Example 8 The same procedure as in Example 7 was carried out except that 0.0193 g of TFMFPhV[PF6]2 and 0.0107 g of dimethylferrocene were added.

[0076] Example 9 Example 7 The same procedure as in Example 7 was carried out except that 0.0399 g of TFMFPhV[PF6]2 and 0.022 g of dimethylferrocene were added.

[0077] Manufacturing example: Manufacturing of electrochromic elements The electrochromic member prepared above was cut into a 10 mm wide x 20 mm long piece and placed on ITO glass. 100 μm thick spacers were placed around the edges of the electrochromic member, and then the top was covered with a different ITO glass. The electrochromic elements thus prepared were defined as Examples 10 to 18, corresponding to Examples 1 to 9 of the electrochromic member, respectively.

[0078] Experimental example: Cyclic voltammetry measurement 20mVs using a potentiometer (biologics, SP240) -1 Current / potential curves were obtained by cyclic voltammetry for Examples 10 to 18 under the conditions shown above. Figure 4 shows the experimental results for Examples 10 to 12, Figure 6 shows the experimental results for Examples 13 to 15, and Figure 6 shows the experimental results for Examples 16 to 18. Referring to Figures 4 to 6, it can be seen that the higher the content of the electrochromic material, the more pronounced the change in current.

[0079] Experimental example: Measuring light absorption rate For Examples 12, 15, and 18, measurements were taken in the range of 400 to 800 nm using a UV-Vis Spectrometer (Perkin Elmer, Lambda 465). Figures 7 to 9 show the experimental results for Examples 12, 15, and 18, respectively. Referring to Figures 7 to 9, Example 12 had the highest absorbance at wavelengths of 552 nm, Example 15 at 605 nm, and Example 18 at 649 nm, indicating that the light absorbance can be adjusted by the applied voltage.

[0080] Experimental example: bleaching and coloring experiment Voltage was applied to Examples 10 to 18, and the state of realizing each color was observed. Figures 10 to 12 are photographs showing the experimental results of Examples 10 to 12, Examples 13 to 15, and Examples 16 to 18, respectively. Referring to Figures 10 to 12, it can be seen that colors are realized depending on the electrochromic material, and that clearer colors are realized in Examples 12, 15, and 18.

[0081] Experimental example: Light transmittance experiment The transmittance of light having wavelengths of 525, 605, and 649 nm was measured for Examples 10 to 18, respectively. The change in light transmittance was observed while coloring and bleaching were performed by applying and removing voltage. Figures 13 to 15 are photographs showing the experimental results for Examples 10 to 12, Examples 13 to 15, and Examples 16 to 18, respectively. Referring to Figures 13 to 15, it can be seen that the higher the content of the electrochromic material, the greater the change in light transmittance, and that Examples 12, 15, and 18 showed particularly excellent changes in light transmittance.

[0082] Experimental Example: Optical Density vs. Charge Density Analysis The relationship between optical density and charge density was analyzed for Examples 10 to 18 at 606 nm and -1.0 V to determine the coloring efficiency (η). Figures 16 to 18 are photographs showing the experimental results for Examples 10 to 12, Examples 13 to 15, and Examples 16 to 18, respectively. Referring to Figures 16 to 17, it can be seen that the higher the content of the electrochromic material, the higher the coloring efficiency (η).

[0083] The present invention is not limited by the above-described embodiments and the accompanying drawings, but is limited by the appended claims. Therefore, various substitutions, modifications, and changes can be made by a person skilled in the art without departing from the technical spirit of the present invention as defined in the claims, and such changes are also within the scope of the present invention.

Claims

1. The method includes mixing a light-transmitting polymer resin, a crosslinking agent, an initiator, an ionic liquid, and an electrochromic material to prepare a mixture; the light-transmitting polymer resin is poly(butyl acrylate); the cross-linking agent forms cross-links between the chains of the poly(butyl acrylate); The ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and the content of the ionic liquid is 150 to 250 parts by weight based on 100 parts by weight of the light-transmitting polymer resin. Method for manufacturing electrochromic members.

2. In the step of preparing the mixture, The content of the crosslinking agent is 1 to 2 parts by weight based on 100 parts by weight of the polymer resin, The content of the initiator is 0.5 to 2 parts by weight, The method for manufacturing an electrochromic member according to claim 1, wherein the content of the ionic liquid is 150 to 250 parts by weight.

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