JPH0149923B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a light-receiving electro-optical display, and more particularly to a peripheral sealant used in an electrochromic (EC) display element that causes continuous electrochromic color change upon application of voltage. Electrochromic display element (EC) is the first
A transparent substrate 1 such as glass shown in the figure, a display electrode 2 formed inside this substrate 1, and this display electrode 2
Electrochromic material (EC) formed on
A display substrate consisting of the layer 3 and a counter electrode substrate having a counter electrode 5 formed on the inside of the back substrate 4 are arranged facing each other with a predetermined gap, and the periphery is bonded with an adhesive, that is, a peripheral sealant 7, and an EC is formed inside. An electrolyte 6 containing ions capable of coloring the layer 3 and, if necessary, a light scattering plate 8 are enclosed. In the EC cell obtained in this way, when a voltage is applied with the display electrode negative, the color of the EC layer 3 changes and a display is performed, and when the polarity is reversed and a voltage is applied, it quickly returns to its original transparent state. to recover. The display performed here is extremely clear and is expected to be applied to various display devices. Currently this type of EC
One of the important issues with the device is the material of the adhesive 7. In order to create a highly reliable EC display device, it must be inert to electrolytes and strong enough to withstand the internal pressure applied during durability tests. Materials with high strength and low moisture and gas permeability are desired, and various materials are being tried. Among them, materials that can be sealed at low temperatures and are stable against the electrolyte to be sealed are important when considering compatibility with EC thin films, which are relatively unstable against heat. resin, polybutadiene or epoxidized polybutadiene resin,
Ethylene tetrafluoride/ethylene copolymer resin, glass frit, etc. have been tried. Since the cured product of silicone resin is flexible, when the internal pressure increases during durability tests, the pressure is absorbed by the sealant itself, so seal peeling and liquid leakage do not occur. However, the moisture permeability and gas permeability of silicone resins are 10 to 100 times higher than those of epoxy resins, so moisture and oxygen can enter during durability tests, resulting in loss of EC coloring and corrosion of electrodes. It had the disadvantage that it could occur. On the other hand, in the case of polybutadiene or epoxidized polybutadiene resin, a certain type of curing agent, organic peroxide, or photopolymerization initiator is added to it and cured by UV irradiation or heat treatment, but the UV irradiation process is complicated during mass production. It is difficult to control, and the moisture permeability of the cured product is several times higher than that of epoxy resin, so in order to maintain durability it is necessary to increase the seal width. Not suitable for making. In addition, when sealing with tetrafluoroethylene-ethylene copolymer resin, heating to approximately 300°C is required during sealing, but the moisture permeability of the upper copolymer resin makes it possible to display by using a heat-resistant EC membrane. It has low gas permeability and high adhesive strength, making it possible to create highly reliable displays. However, since the sealing temperature is high, manufacturing costs are somewhat high, which is a disadvantage. On the other hand, glass frit used as a sealant for parts of liquid crystal displays and fluorescent display tubes has the lowest gas permeability and moisture permeability, but it requires heat treatment at 400 to 500°C during sealing. . At present, there are no known EC materials that can withstand temperatures of 400 to 500°C, and it is extremely difficult to make an EC display using frit seals. On the other hand, the sealant often used for liquid crystal displays is epoxy adhesive, which is used as a sealant for ECDs because it can be bonded at relatively low temperatures and can be produced through a simple process. It is desirable to do so, and many attempts have been made.
However, in the examples that have been tried to date, it has been reported that the epoxy sealant has the disadvantage of swelling or leakage due to exposure to the electrolyte solution. As described above, none of the peripheral sealants for ECDs that have been proposed so far satisfy the required properties in a well-balanced manner, and various products are still being tried. Based on the recognition of such problems, the present inventors have
As a result of various studies and examinations, we have come to the interesting finding that the type of curing agent in the epoxy adhesive is related to the reliability of ECD. The present invention was made based on the above-mentioned study results, and has been developed as a peripheral sealant for ECD.
It is characterized by using an epoxy adhesive that is cured using a curing agent containing various aromatic amines. When this sealant is used, it will not be contaminated by the electrolyte of the ECD, has low moisture permeability and gas permeability, and has strong adhesive strength, making it a highly reliable ECD.
ECD has the advantage of being able to produce products, high productivity due to low-temperature processing, and lower manufacturing costs.
It is extremely useful for practical purposes. The epoxy resin in the present invention is not particularly limited, and includes conventionally known epoxy resins such as aromatic, alicyclic, and aliphatic, and one or more types of such known epoxy resins may be selected depending on the workability. A mixture of these is selected as appropriate. The aromatic amine in the present invention is not particularly limited, but representative examples include metaphenylene diamine (MPD), diaminodiphenylmethane (DDM), diaminodiphenyl sulfone (DDS), etc. In general, all compounds containing a phenyl group and an amine group are included, and when used, it is not limited to one type, and mixtures thereof and modified products thereof are also included. Further, during use, other curing agents may be added as reaction accelerators in addition to the aromatic amine curing agent, and the mixing ratio with respect to the epoxy resin is not particularly limited. On the other hand, epoxy adhesives cured with hardening agents such as aliphatic amines, acid anhydrides, and imidazole that have been used up to now cannot be used because they are susceptible to organic electrolytes. In addition, the EC material for ECD in the present invention is one that can withstand the curing temperature of epoxy, 100 to 200°C.
Any EC material can be used, a typical example being tungsten oxide. As an electrolyte, it does not deteriorate the epoxy resin.
Known ECD as long as it can decolorize the EC substance
Although any electrolyte can be used, it is preferable to use an electrolyte prepared by dissolving a substance that generates protons or lithium ions in a non-aqueous solvent.A specific example is an electrolyte prepared by dissolving lithium perchlorate in propylene carbonate. This will be explained in more detail below with reference to Examples. Example A 7-segment numeric display pattern was formed on transparent conductive glass by photoetching, a metal mask lacking each segment to be displayed was adhered thereon, and WO ₃ was formed by vacuum evaporation.
Then, SiO ₂ was formed only on the transparent conductive film not used for display as a display electrode, and WO ₃ was formed on a transparent conductive film formed on a part of the inner surface of the concave cover glass as a counter electrode. Prepared. As a sealant, silicone resin adhesive (SE1700 manufactured by Toray Silicon Co., Ltd.), epoxidized polybutadiene resin adhesive (BF1000 manufactured by Adeka Argus Chemical Co., Ltd.),
Select a tetrafluoroethylene ethylene copolymer resin adhesive (Afron COP manufactured by our company) and an epoxy resin adhesive. For the epoxy resin adhesive, use Epicoat 828 manufactured by Ciel as the epoxy resin and aromatic amine as the curing agent. Four types of curing agent (H-94 manufactured by Nippon Gosei Co., Ltd.), aliphatic amine curing agent (H-82 manufactured by Nippon Gosei Co., Ltd.), imidazole curing agent (2E48Z manufactured by Shikoku Kasei Co., Ltd.), and phthalic anhydride were used. Using. After sealing the periphery of the above two substrates under the sealing conditions shown in Table 1, a solution of 1 molar concentration was added from the injection hole.
After injection of propylene carbonate containing _LiClO4 ,
The injection hole was sealed with metal. As a result of subjecting this display to a 300-hour humidity test at 60°C and 90%RH, as shown in Table 1, aliphatic amines,
Epoxy adhesives that use imidazole and acid anhydride curing agents (phthalic anhydride) swell and the electrolyte inside leaks, creating large bubbles, and voltage cannot be applied. However, no coloration was observed. On the other hand, a cell sealed with a silicone resin adhesive had no visible leakage, but even when voltage was applied, the display part was lightly colored, and electrode blackening occurred during a 1 Hz 1 hour flashing test. In the case of the polybutadiene resin adhesive, almost the same results as with the silicone resin adhesive were obtained. On the other hand, the cell whose periphery was sealed with an epoxy adhesive using an aromatic amine curing agent and a tetrafluoroethylene-ethylene copolymer resin did not leak even after the initial durability test, and the coloring state due to voltage application remained at the initial state. Good results were obtained with no difference. As described above, by sealing the periphery with an epoxy adhesive using an aromatic amine curing agent, the durability is almost equivalent to that of cells sealed with tetrafluoroethylene-ethylene copolymer resin, which must be sealed at high temperatures. In addition to being able to produce ECDs that exhibit the

[Table] In this way, by sealing the ECD of the present invention with a specific epoxy resin, it is possible to achieve a seal with good durability at low temperatures, and the ECD of the present invention can be sealed using a specific epoxy resin. This enables mass production at lower temperatures and higher productivity than conventional seals. Furthermore, the ECD of the present invention is not limited to the above-mentioned structure, but includes using two parallel substrates, providing a partition wall, using a transmission type, providing a counter electrode on the front side, and using a third electrode or a reference electrode. Various applications are possible, such as installing a telephone pole, using an EC material, carbon, or other material as the counter electrode, using a solid electrolyte, using a stacked structure, and providing an injection port on the back or side. It is sufficient if it is driven by a driving method. ECDs manufactured in this manner are used in various applications that take advantage of their memory properties, including for watches.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a basic ECD element. 2: display electrode, 3: EC layer, 5: counter electrode,
6: Electrolyte.

Claims (1)

[Claims] 1. In an electrochromic (EC) display element that includes at least an electrolyte between a display electrode substrate and a counter electrode substrate, and the peripheries of both substrates are sealed with an adhesive, at least one type of fragrance is used as a peripheral sealant. An electrochromic display element characterized by using an epoxy adhesive using a curing agent containing a group amine.