Patent Application
20240168314
The present invention relates to an electrochromic element whose coloring and discoloring can be reversibly controlled by electricity and a lens for spectacles.
Electrochromic elements that utilize an electrochromism phenomenon in which a voltage is applied to cause a reversible oxidation-reduction reaction and colors are reversibly changed are used as, for example, lenses for spectacles. PTL 1 discloses an electrochromic element including a pair of substrates, an electrode layer arranged between the substrates and an electrochromic layer.
Incidentally, electrochromic elements are elements that utilize an electrochromism phenomenon in which a voltage is applied to both electrodes to cause a reversible oxidation-reduction reaction and colors are reversibly changed.
However, there is a problem in that the responsiveness decreases due to water or oxygen entering from the side of the electrochromic element.
The present invention has been made in order to address the above problems, and an objective of the present invention is to provide an electrochromic element in which a decrease in responsiveness is minimized by making a side of the electrochromic element have gas barrier properties, and a lens for spectacles.
An electrochromic element in the present invention is an electrochromic element that includes a pair of electrode layers and an electrochromic layer arranged between the electrode layers, wherein a barrier layer surrounding the electrochromic layer is provided.
In the present invention, preferably, the barrier layer has gas barrier properties and adhesive properties.
In the present invention, the electrochromic layer may be arranged between a pair of substrates each having the electrode layer on the inner surface, and a sealing layer for sealing between the pair of substrates and the barrier layer may be separately provided.
In the present invention, preferably, the barrier layer is formed of a high resistance material.
In the present invention, preferably, the barrier layer is formed of a UV curing resin, a thermosetting resin, or a low-melting-point material.
A lens for spectacles in the present invention includes the electrochromic element described above.
According to the electrochromic element of the present invention, a barrier layer is provided around the electrochromic layer, and accordingly, it is possible to improve gas barrier properties and it is possible to obtain excellent responsiveness.
Hereinafter, a mode for implementing the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail.
Electrochromic elements are elements that utilize an electrochromism phenomenon in which a voltage is applied to both electrodes to cause a reversible oxidation-reduction reaction and colors are reversibly changed. For example, electrochromic elements can be used as lenses for spectacles, and can function as sunglasses in bright places and clear lenses in dark places. It is possible to adjust the brightness to an optimal level by operating a switch or automatically.
The electrochromic element has a structure including a pair of electrode layers and an electrochromic layer arranged between the electrode layers.
Incidentally, when water or oxygen enters the electrochromic layer from the side of the electrochromic element, there is a problem that the responsiveness of color change due to an electrochromism phenomenon decreases such as a decrease in the reversibility of the oxidation-reduction reaction.
Therefore, the inventors conducted extensive studies and as a result, found that, when a barrier layer is arranged to surround the electrochromic element, penetration of water or oxygen into the electrochromic layer in a side direction is inhibited, and the responsiveness is improved. Hereinafter, the layer structure of the electrochromic element in the present embodiment will be described in detail.
The electrochromic element 10 includes a pair of a first substrate 3 and a second substrate 4, a pair of a first electrode layer 5 and a second electrode layer 6 provided on the inner surfaces of the first substrate 3 and the second substrate 4, and an electrochromic layer 7 provided between the first electrode layer 5 and the second electrode layer 6. The electrochromic layer 7 includes a reduction layer 7a arranged on the side of the first electrode layer 5, an oxidation layer 7b arranged on the side of the second electrode layer 6, and an electrolyte layer 7c provided between the reduction layer 7a and the oxidation layer 7b. In this manner, in the electrochromic element 10, the second substrate 4/the second electrode layer 6/the oxidation layer 7b/the electrolyte layer 7c/the reduction layer 7a/the first electrode layer 5/the first substrate 3 are laminated in order from the bottom of
The electrochromic element 10 shown in
The substrates 3 and 4 constituting the electrochromic element 10 are, for example, in the form of a film or sheet, and are required to be transparent and have high transmittance. The substrates 3 and 4 are, for example, resin substrates that can be molded in a mold such as a polycarbonate resin, an acrylic resin, an epoxy resin, and a phenolic resin and glass substrates. If the substrates 3 and 4 are formed of a polycarbonate resin, this is advantageous because transparency and high transmittance can be obtained and in terms of production cost.
Properties required for the electrode layers 5 and 6 constituting the electrochromic element 10 include transparency, high transmittance, and excellent conductivity. In order to satisfy such properties, the electrode layers 5 and 6 are transparent electrode layers, and an indium tin oxide (ITO) is particularly preferably used.
As shown in
For the reduction layer 7a, the oxidation layer 7b and the electrolyte layer 7c constituting the electrochromic layer 7, existing materials can be used.
The reduction layer 7a is a layer that develops colors according to a reduction reaction. For the reduction layer 7a, existing reduced electrochromic compounds can be used. It does not matter whether it is an organic substance or an inorganic substance, and although not limited, examples include azobenzene, anthraquinone, diarylethene, dihydroprene, dipyridine, styryl, styryl spiropyran, spirooxazine, spirothiopyran, thioindigo, tetrathiafulvalene, terephthalic acid, triphenylmethane, triphenylamine, naphthopyran, viologen, pyrazoline, phenazine, phenylenediamine, phenoxazine, phenothiazine, phthalocyanine, fluoran, fulgide, benzopyran, and metallocene substances, tungsten oxide, molybdenum oxide, iridium oxide, and titanium oxide.
The oxidation layer 7b is a layer that develops colors according to an oxidation reaction. For the oxidation layer 7b, existing oxidized electrochromic compounds can be used. It does not matter whether it is an organic substance or an inorganic substance, and although not limited, for example, it can be selected from among a composition containing a radically polymerizable compound including triarylamine, a Prussian blue type complex, nickel oxide, iridium oxide and the like.
The electrolyte layer 7c has electronic insulation and ionic conductivity and is preferably transparent. The electrolyte layer 7c may be a solid electrolyte, a gel, or a liquid. In order to maintain high ionic conductivity, a gel is preferable. Although not limited, for example, existing electrolyte materials such as inorganic ion salts such as alkali metal salts and alkaline earth metal salts, quaternary ammonium salts and acids can be used.
The barrier layer 11 will be described. As shown in
It is preferable that the barrier layer 11 have gas barrier properties and adhesive properties. Gas barrier properties can be evaluated by the water vapor transmission rate (WVTR) and the O2 transmittance. Gas barrier properties can be measured using a dry/wet sensor (Lyssy) method, a Mocon (MOCON) method, a gas chromatography method, an API-MS method, a Ca corrosion method, and a differential pressure method. For example, the water vapor transmission rate and the O2 transmittance are measured according to “Mocon method (JIS K 7129 (B)).” In the present embodiment, the water vapor transmission rate (WVTR) under an atmosphere of a temperature of 40° C. and a humidity of 90% RH is 100 (g/m2·day) or less, preferably 80 (g/m2·day) or less, more preferably 60 (g/m2·day) or less, still more preferably 50 (g/m2·day) or less, yet more preferably 25 (g/m2·day) or less, yet more preferably 10 (g/m2·day) or less, yet more preferably 7 (g/m2·day) or less, and most preferably 5 (g/m2·day) or less. In addition, although the lower limit value of the water vapor transmission rate is not limited, for example, the lower limit value can be set to about 10-6 (g/m2·day). The O2 transmittance under an atmosphere of a temperature of 20° C. and a humidity of 65% RH is preferably 70 (cc/m2·day·atm) or less, more preferably 60 (cc/m2·day·atm) or less, still more preferably 55 (cc/m2·day·atm) or less, yet more preferably 40 (cc/m2·day·atm) or less, yet more preferably 30 (cc/m2·day·atm) or less, yet more preferably 20 (cc/m2·day·atm) or less, and most preferably 15 (cc/m2·day·atm) or less.
In the present embodiment, it is necessary to satisfy at least the water vapor transmission rate between the water vapor transmission rate and the O2 transmittance of the barrier layer 11, and it is preferable to satisfy both.
The barrier layer 11 is preferably formed of a material that can be patterned. For example, at least one of a UV curing resin, a thermosetting resin, a low-melting-point alloy, and a low-melting-point glass can be selected. A UV curing resin is preferable because it can be cured without requiring a high-temperature heat treatment. Specifically, acrylic resin, epoxy resin, silicone rubber materials and the like can be selected. Since all of these materials have excellent adhesive properties, in order for gas barrier properties to satisfy the above numerical value range, two or more types of materials may be mixed, or as shown in
In addition, for the barrier layer 11, as an example, “Photolec E” (commercially available from Sekisui Chemical Co., Ltd.) or an active barrier sealing material (commercially available from SAES Getters S.p.A.) can be used.
The thickness of the barrier layer 11 is formed by the interval between the pair of substrates 3 and 4, and specifically, it is about 0.1 μm to 200 μm, preferably about 1 μm to 100 μm, and more preferably about 1 μm to 50 μm.
The barrier layer 11 has gas barrier properties and adhesive properties. That is, the barrier layer 11 also functions as a sealing layer that bonds the pair of substrates 3 and 4. “Adhesive properties” can be evaluated by the peel strength using, for example, a Tensilon tensile tester.
If the barrier layer 11 does not have adhesive properties, each of the substrates 3 and 4 and the barrier layer 11 are bonded, for example, with an adhesive layer (not shown) therebetween.
In addition, the barrier layer 11 is preferably formed of a high resistance material. The barrier layer 11 has a higher electrical resistivity than the electrode layers 5 and 6. The electrical resistivity of the barrier layer 11 is preferably 500 Ω·cm or more and more preferably 1 kΩ·cm or more. In this manner, when the electrical resistivity of the barrier layer 11 increases, it is possible to prevent a leakage current between the electrode layers 5 and 6 through the barrier layer 11.
When the width T1 of the barrier layer 11 is wider, adhesive properties (seal strength) can be better. Therefore, as shown in
In addition, it is preferable that the barrier layer 11 have transparency depending on usage applications and forms. For example, in applications of the lens for spectacles, when the position of the barrier layer 11 is exactly at the frame position, the barrier layer 11 does not necessarily have to be transparent. However, it is preferable that the barrier layer 11 be transparent depending on the part in which the barrier layer 11 does not cover the frame or other applications. “Transparency” means a state of being transparent in a visible range and can be defined by the absorbance in the visible range. For example, the absorbance in the visible range measured using an UV-VIS-NIR spectrophotometer UH4150 (commercially available from Hitachi High-Tech Science Corporation) at a wavelength of 400 to 750 mm is preferably 0.1 Abs or less and more preferably 0.09 Abs or less.
In addition, the “transparency” of the barrier layer 11 means that light is not scattered and can be defined by the haze. Generally, the haze can be determined by measuring the total light transmittance and the diffuse transmittance of the barrier layer 11 using an integrating sphere light transmittance measurement device and according to the following formula.
haze value (%)=diffuse transmittance (%)/total light transmittance (%)×100
Here, the diffuse transmittance is a value obtained by subtracting the parallel light transmittance from the total light transmittance.
In the present embodiment, the haze value is 30% or less, preferably 20% or less, more preferably 10% or less, and still more preferably 1% or less.
The transparency of the barrier layer 11 preferably satisfies both the visible absorbance and the haze.
In the first embodiment shown in
The electrochromic element 20 according to the second embodiment shown in
In
In addition, in
In the configuration shown in
According to the embodiment shown in
Examples of adhesives applicable to the present embodiment include i) urea resin adhesives, ii) melamine resin adhesives, iii) phenolic resin adhesives, iv) solvent adhesives such as vinyl acetate adhesives and rubber adhesives, v) aqueous adhesives such as vinyl acetate resin emulsion adhesives, vinyl acetate copolymer resin emulsion adhesives, acrylic resin emulsion adhesives, aqueous polymeric isocyanate adhesives, and synthetic rubber latex adhesives, vi) hot melt adhesives, vii) reactive adhesives such as epoxy resin adhesives, cyanoacrylate adhesives, polyurethane adhesives, and acrylic resin adhesives, viii) modified silicone resin adhesives, ix) silylated urethane adhesives, and x) inorganic adhesives such as flint glass and low-melting-point metals.
The above adhesive can be applied not only for the sealing layer 21 but also for the barrier layer 11. However, when used for the barrier layer 11, it is preferable to disperse inorganic fine particles such as zinc oxide, silicon oxide, titanium oxide, and zirconium oxide or fluorine powders such as acrylic resin powder, epoxy powder, polyester, and PTFE to improve barrier properties. In this case, the average particle size of dispersed particles is preferably 10 nm to 100 μm and more preferably 100 nm to 50 μm. In addition, in consideration of the adhesive strength, it is preferable to use a reactive adhesive, and in consideration of barrier properties, it is preferable to use a reactive adhesive and an inorganic adhesive.
Although applications of the electrochromic element of the present embodiment are not limited, it can be preferably applied to a light control lens for spectacles.
The electrochromic element of the present embodiment may be applied to those other than the lens for spectacles. Examples thereof include electrochromic light control devices and anti-glare mirrors.
In
As shown in
In the present embodiment, as shown in
In the present embodiment, in the process of producing an electrochromic element, it is possible to form a barrier layer in the process of bonding the pair of substrates 3 and 4, and it is possible to produce an electrochromic element having excellent gas barrier properties without complicating the producing process.
Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples.
In the experiment, the following laminate was formed using an adhesive, and the water vapor transmission rate (WVTR) and the O2 transmittance were determined.
An adhesive was applied to a 100 μm polycarbonate film, a 100 μm polycarbonate film was additionally laminated to form a polycarbonate film/adhesive/polycarbonate film laminate.
Using the laminate, the water vapor transmission rate and the O2 transmittance were determined. The water vapor transmission rate and the O2 transmittance were measured by the Mocon method (JIS K 7129 (B)). The water vapor transmission rate (WVTR) was measured under an atmosphere of a temperature of 40° C. and a humidity of 90% RH. The O2 transmittance was measured under an atmosphere of a temperature of 20° C. and a humidity of 65% RH.
A laminate was formed using an acrylic resin-based adhesive as the adhesive (1). The laminate using the adhesive (1) had a water vapor transmission rate (WVTR) of about 50 (g/m2·day) and an O2 transmittance of about 55 (cc/m2·day·atm).
A laminate was formed using an epoxy resin-based adhesive as the adhesive (2). The laminate using the adhesive (2) had a water vapor transmission rate (WVTR) of about 25 (g/m2·day) and an O2 transmittance of about 30 (cc/m2·day·atm).
A laminate was formed using an adhesive in which 35 wt % of PTFE powder particles with an average particle size of 2 μm were dispersed in an acrylic resin-based adhesive as the adhesive (3). The laminate using the adhesive (3) had a water vapor transmission rate (WVTR) of about 5 (g/m2·day) and an O2 transmittance of about 15 (cc/m2·day·atm).
A laminate was formed using an adhesive in which 25 wt % of silica powder particles with an average particle size of 20 μm were dispersed in an epoxy resin-based adhesive as the adhesive (4). The laminate using the adhesive (4) had a water vapor transmission rate (WVTR) of about 5 (g/m2·day) and an O2 transmittance of about 10 (cc/m2·day·atm).
A laminate was formed using a vinyl acetate-based adhesive as the adhesive (5). The laminate using the adhesive (5) had a water vapor transmission rate (WVTR) of about 155 (g/m2·day) and an O2 transmittance of about 80 (cc/m2·day·atm).
An electrochromic element having the configuration shown in
An electrochromic element having the configuration shown in
An electrochromic element having the configuration shown in
An electrochromic element having the configuration shown in
An electrochromic element having the configuration shown in
An electrochromic element having the configuration shown in
In Experimental Example 1, after the sample was left in a constant temperature and humidity layer, slight coloring unevenness occurred at the ends during current application, but was not to a level that would cause problems in practical use.
In Experimental Example 2, after the sample was left in a constant temperature and humidity layer, slight coloring unevenness occurred at the ends during current application, but it was better than Example 1 and was not to a level that would cause problems in practical use.
In Experimental Example 3 to Experimental Example 5, no change was observed before and after the sample was left in a constant temperature and humidity layer, during current application, the entire sample was uniformly colored, and favorable results were obtained.
In Experimental Example 6, the color at the ends during current application coloring was faded, a strong gradation appeared, and the sample was determined to be unusable. This was thought to be due to changes such as entering of water, oxygen and the like from the ends and deterioration of the electrochromic material.
Based on the experiment results, Experimental Example 1 to Experimental Example 5 were taken as examples, and Experimental Example 6 was taken as a comparative example. In addition, it can be understood that Example 3 to Example 5 among the examples were better.
Since the electrochromic element of the present invention has excellent gas barrier properties, when the electrochromic element is used as, for example, a lens for light control spectacles, it is possible to obtain a feeling of use with excellent responsiveness.
Priority is claimed on Japanese Patent Application No. 2021-082861, filed May 17, 2021, the content of which is incorporated herein by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-082861 | May 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/020522 | 5/17/2022 | WO |
