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(11) | EP 3 547 332 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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FLEXIBLE TRANSPARENT CONDUCTIVE ELECTRODE FLEXIBLE TRANSPARENTE LEITFÄHIGE ELEKTRODE ÉLECTRODE CONDUCTRICE TRANSPARENTE SOUPLE |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
ABSTRACT
[0001] The present invention discloses a flexible transparent conductive electrode. The flexible transparent conductive electrode is made of transparent flexible base materials and a transparent flexible substrate coated with a silver nanowire coating. The process of fabricating the flexible transparent conductive electrode comprises a few steps as followings: adding silver nanowire aqueous dispersion, aqueous acrylic resin, triethylenetetramine, 1-2 parts of p-methylsulfonyl toluene, 0.1-0.3 pars of hydrogenated castor oil and a mixture solvent into a vacuum mixer where evenly mixed, vacuum defoamed, and thus the coating is prepared. The concentration of the silver nanowire in the coating is 2-10mg/mL and the mixture solvents used are the mixture of alcohol and ketone. The film is coated with above coating and moved into a vacuum dryer to be dried at 150°C for 3-10min so that the solvents in the coating are completely volatilized and the flexible transparent conductive electrode is obtained. The flexible transparent conductive electrode of the invention has characteristics of the lower conductive resistivity, less stacks of silver nanowires, higher uniformity of conductivity and better optical transmittance comparison with the existing products.
FLEXIBLE TRANSPARENT CONDUCTIVE ELECTRODE
FIELD OF THE INVENTION
[0002] The present invention relates to a technology of silver nanowires, particularly relates to a flexible transparent conductive electrode. insert content of description insertion page 1a here
BACKGROUND OF THE INVENTION
[0003] US 2015/166798 A1 discloses a transparent conductive film including metal nanowires and a colored compound adsorbed by the metal nanowires. The metal nanowires are a material which absorbs light in the visible light region, and also each has a functional group which is bound to a metal constituting the metal nanowire.
[0004] Metal oxides, especially ITO, has the characteristics of good optical transmittance in visible region and low resistivity which have been hot spots in researches and applications of transparent conductive electrodes in the past 5 decades. However, metal oxides have the disadvantages as limited conductivity, brittle and hard to deform. Concurrently, scarce resources and risen prices are unable to meet the requirements for developing the modern optoelectronic devices. Two dimensional micro-nano new materials and structured thin film electrodes are new fields of transparent conductive electrodes with the development of micro nanotechnology in recent years, such as conductive thin film of polymers, carbon nanotube film, graphene film and metal nanowire film. Unique morphology contributes great flexibility and electron mobility to graphene film, but large scale of production is not mature; uniform dispersion and resistance between carbon tubes limit the inner surface conductivity of carbon tubes film which need a little bit large aspect ratio. Transparent conductive film has advantages of not only great conductivity but also good optical transmission while nanometallic silver wire electrode's are excellent. Micro-nano silver wires can be used as electrode materials with less energy consumption (compared with electrode of oxide thin film) since silver is an electric conductor with great electrical conductivity. At the same time, micro nano structure of metal with plasma effect increases transmittance while diameters of micro silver nanowires' particles are smaller than the incident wavelength of visible light, and perfect photoelectric properties are achieved for electrodes. Simultaneously, micro silver nanowire electrode is benefit for flexible industries and large scale productions with lower cost. Therefore, the micro silver nanowire electrode will be a favorable alternative to ITO transparent conductive electrode. The additives for preparing coating fluid of micro silver nanowires determines performances of the electrode. Therefore, various additives are used to prepare different coating fluid for different properties in order to get better performances. Properties as conductivity and flexural endurance are still to be improved by using current formula. To overcome the problems and go on improving in the prior art are directions for those skilled in this field.
SUMMARY OF THE INVENTION
[0005] The object of the present invention is to provide a flexible transparent conductive electrode, in which silver nanowire coating is used. It can not only reduce the content of silver nanowires, effectively disperse silver nanowires, reduce the conductive resistivity, but also improve the bending resistance to be more than 5000 bending times .
[0006] To achieve the above purpose, the present invention is defined in independent claim 1. The dependent claims define embodiments of the invention. In other words, the technical scheme adopted by the present invention is a flexible transparent conductive electrode consisting of a transparent flexible substrate and a silver nanowire coating, which the coating is coated on the surface of the transparent flexible substrate and the thickness of the silver nanowire coating is 20-100 microns after dried. The silver nanowire coating comprises following compounds by weight: 100 parts of silver nanowire aqueous dispersion, 5-8 parts of aqueous acrylic resin, 2-5 parts of triethylenetetramine, 1-2 parts of p-methylsulfonyl toluene, 0.2-0.5 parts of polyvinyl alcohol aqueous solution, 0.2-0.4 parts of alkanolamide, 0.3-0.5 parts of isopropoxyethanol, 0.1-0.3 parts of hydrogenated castor oil, 30-40 parts of mixture solvents.
[0007] The process of fabricating the flexible transparent conductive electrode comprises a few steps as followings:
The first step: 100 parts of silver nanowire aqueous dispersion, 5-8 parts of aqueous acrylic resin, 2-5 parts of triethylenetetramine, 0.1-0.3 parts of hydrogenated castor oil and 30-40 parts of mixture slovents are all added into a vacuum mixer where evenly mixed, vacuum defoamed, and then the mixture solution is prepared, in which the concentration of the silver nanowire in the aqueous dispersion is 2-10mg/mL and the mixture solvent is a mixture of alcohol solvents and ketone solvents;
The second step: 1-2 parts of p-methylsulfonyl toluene and 0.2-0.5 parts of polyvinyl alcohol aqueous solution are added into the mixture solution during the process of stirring. The water-soluble resin fluid is water-soluble polyester resin fluid after evenly mixed for 10min stirring;
The third step: 0.2-0.4 parts of alkanolamide and 0.3-0.5 parts of isopropoxyethanol are added into a vacuum mixer to be continually stirred and evenly mixed. The coating based on the silver nanowires is prepared ;
The fourth step: Transparent flexible substrate is PET film which uniformly coated with the silver nanowire coating by using miceo gravure. The distances between the bars are 15µm and the rolling speed for coating is 80cm/min, a uniform wet film is formed on the surface of the transparent flexible substrate;
The fifth step: The wet film coated with above coating is completely volatilized after dried in a vacuum dryer at 150 °C for 3-10min,and the flexible transparent conductive electrode is obtained.
[0008] Further improvements of the invention are as follows:
- 1. In according with the invention, the silver nanowires in the silver nanowire aqueous dispersion has the diameters of 20-150nm and lengths of 50-500mm.
- 2. In according with the invention, the alcohols is one of methanol, ethanol and isopropanol.
- 3. In according with the invention, the ketones solvent is one of acetone, butanone, cyclohexanone and isophorone.
- 4. In according with the invention, the mixture solution is a mixture of alcohols and ketones with 10:(2-4) by weight.
[0009] The invention has the following advantages and characteristics in comparison with the prior art:
The flexible transparent conductive electrode of the invention contains 100 parts of silver nanowire aqueous dispersion, 5-8 parts of water-borne acrylic resin, 0.2-0.5 parts of polyvinyl alcohol aqueous solution, 0.2-0.4 parts of alkyholamide, 0.3-0.5 parts of isopropoxyethylanol as a primary formula, and further adds with 2-5 parts of triethylenetetramine and 1-2 parts of p-methylsulfonyl toluene which reduces the content of silver nanowires, effectively disperses the silver nanowires, reduces the resistivity and improve the bending resistance to be more than 5000 bending times. Furthermore, the formula added with 0.3-0.5 parts of isopropoxyethanol and a mixture solvent of alcohols and ketones with 10: (2-4) by weight, which has advantages of effectively adjusting viscosity and drying rate of the coating further avoiding stacks of silver nanowires, ensuring uniformity of conductivity and improving transmittance.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0010] The following is detailed description of certain embodiments of the present invention.
formulations 1-4: a flexible transparent conductive electrode is comprised of a transparent flexible substrate coated with a silver nanowires coating at a thickness of 20-100µm after the silver nanowire coating is dried. The silver nanowire coating is consist of the following ingredients by weight as shown in Table 1:
| Ingredients | formulation 1 (parts) | formulation 2 (parts) | formulation 3 (parts) | formulation 4 (parts) |
| Silver Nanowire Aqueous Dispersion | 100 | 100 | 100 | 100 |
| aqueous Acrylic Resin | 6 | 5 | 6.2 | 7 |
| Triethylenetetramine | 3 | 2.2 | 5 | 4 |
| p-methylsulfonyl toluene | 1. 8 | 1 | 1.5 | 1.2 |
| PVA Aqueous Solution | 0.24 | 0.4 | 0. 3 | 0. 45 |
| Alkanolamide | 0.3 | 0.35 | 0.4 | 0. 26 |
| Isopropoxyethanol | 0.4 | 0. 5 | 0.35 | 0.42 |
| Hydrogenated Castor Oil | 0. 15 | 0. 25 | 0.1 | 0.2 |
| Mixture Solvents | 35 | 32 | 38 | 35 |
[0011] In the formulation 1, wherein the mixture solution is a mixture of methanol and cyclohexanone of 10:2 by weight; In the formulation 2, wherein the mixture solution a mixture of isopropanol and butanone of 10:2.5 by weight; In the formulation 3, wherein the mixture solution is a mixture of ethanol and cyclohexanone of 10:3 by weight in; In the formulation 4, wherein the mixture solution is a mixture of methanol and isophorone of 10:3.8 by weight.
[0012] The process of fabricating the flexible transparent conductive electrode comprises a few steps as followings:
The first step: 100 parts of silver nanowire aqueous dispersion, 5-8 parts of aqueous acrylic resin, 2-5 parts of triethylenetetramine, 0.1-0.3 parts of hydrogenated castor oil and 30-40 parts of mixture slovents are all added into a vacuum mixer where evenly mixed, vacuum defoamed, and then the mixture solution is prepared, in which the concentration of the silver nanowire in the aqueous dispersion is 2-10mg/mL and the mixture solvent is a mixture of alcohol solvent and ketone solvent.
The second step: 1-2 parts of p-methylsulfonyl toluene and 0.2-0.5 parts of polyvinyl alcohol aqueous solution are added into the mixture solution during the process of stirring. The water-soluble resin fluid is water-soluble polyester resin fluid after evenly mixed for 10min stirring;
The third step: 0.2-0.4 parts of alkanolamide and 0.3-0.5 parts of isopropoxyethanol are added into a vacuum mixer to be continually stirred and evenly mixed. The coating based on the silver nanowires is prepared;
The fourth step: Transparent flexible substrate is PET film which uniformly coated with the silver nanowire coating by using miceo gravure. The distances between the bars are 15µm and the rolling speed for coating is 80cm/min, a uniform wet film is formed on the surface of the transparent flexible substrate;
The fifth step: The wet film coated with above coating is completely volatilized after dried in a vacuum dryer at 150 °C for 3-10min,and the flexible transparent conductive electrode is obtained.
[0013] The silver nanowires in the above coating have the diameters of 20-150nm and lengths of 50-500mm:
The tested results of the flexible transparent conductive electrode in the Embodiment 1-4 are shown in Table 2:
| Embodiment 1 | Embodiment 2 | Embodiment 3 | Embodiment 4 | |
| Resistance(Ω/square) (Four-probe Resistance Tester) | 31 | 30 | 30 | 32 |
| Adhesion(Vertical Pulled with 3M600) | No shedding | No shedding | No shedding | No shedding |
| Transmittance(%)(WG W Optical Haze Meter) | 92 | 92 | 91 | 92 |
| Haze(WGW Optical Haze Meter) | 1. 2 | 1. 3 | 1. 2 | 1. 3 |
| Flexural Endurance(time) | >5000 | >5000 | >5000 | >5000 |
[0014] The characteristics of the flexible transparent electrode which is provided in the present invention have thus been shown in Table 2 to be achieved in reducing the content of silver nanowires, effectively dispersing the silver nanowires, reducing resistivity and improve the bending resistance to be more than 5000 bending times; and effectively adjusting the viscosity and drying rate of coating fluid, further avoiding stacks of the silver nanowires, ensuring uniformity of the conductivity and improving transmittance.
[0015] The embodiments are only to illustrate the technical conception and characteristics of the present invention, the purpose of which is to enable people familiar with the technology to understand the contents of the present invention and to implement it, and not to limit the scope of protection of the present invention as defined by the claims.
the process of fabricating the flexible transparent conductive electrode comprises following steps:
step 1, 100 parts of silver nanowire aqueous dispersion, 5-8 parts of aqueous acrylic resin, 2-5 parts of triethylenetetramine, 0.1-0.3 parts of hydrogenated castor oil and 30-40 parts of a mixture of slovents are all added into a vacuum mixer where evenly mixed, vacuum defoamed, and then the mixture solution is prepared, in which the concentration of the silver nanowire in the aqueous dispersion is 2-10mg/mL and the mixture solvent is a mixture of alcohol solvent and ketone solvent;
step 2, 1-2 parts of p-methylsulfonyl toluene and 0.2-0.5 parts of polyvinyl alcohol aqueous solution are added into the mixture solution during the process of stirring. The water-soluble resin fluid is water-soluble polyester resin fluid after evenly mixed for 10min stirring;
step 3, 0.2-0.4 parts of alkanolamide and 0.3-0.5 parts of isopropoxyethanol are added into a vacuum mixer to be continually stirred and evenly mixed. The coating based on the silver nanowires is prepared ;
step 4,Transparent flexible substrate is PET film which uniformly coated with the silver nanowire coating by using a method of wire rod rolling. The distances between the wire and rod are 15µm and the rolling speed for coating is 80cm/min, a uniform wet film is formed on the surface of the transparent flexible substrate;
step 5,The wet film coated with above coating is completely volatilized after dried in a vacuum dryer at 150 °C for 3-10min,and the flexible transparent conductive electrode is obtained.
wobei der Prozess des Herstellens der flexiblen transparenten leitfähigen Elektrode folgende Schritte umfasst:
Schritt 1: 100 Teile von wässriger Silbernanodrahtdispersion, 5-8 Teile von wässrigem Acrylharz, 2-5 Teile von Triethylentetramin, 0,1-0,3 Teile von hydriertem Castoröl und 30-40 Teile von einer Mischung von Lösungsmitteln werden alle in einen Vakuummischer hinzugegeben, dort gleichmäßig gemischt, vakuumentschäumt, und dann wird die Mischlösung präpariert, wobei die Konzentration des Silbernanodrahts in der wässrigen Dispersion 2-10 mg/mL ist, und die Mischlösung eine Mischung von Alkohollösungsmittel und Ketonlösungsmittel ist;
Schritt 2: 1-2 Teile von p-Methylsulfonyltoluol und 0,2-0,5 Teile von wässriger Polyvinylalkohollösung werden in die Mischlösung während des Prozesses des Rührens hinzugefügt; wobei das wasserlösliche Harzfluid ein wasserlösliches Polyesterharzfluid nach gleichmäßiger Mischung während 10 min Rührens ist;
Schritt 3: 0,2-0,4 Teile von Alkanolamid und 0,3-0,5 Teile von Isopropoxyethanol werden in einen Vakuummischer zum kontinuierlichen Rühren und gleichmäßigen Mischen hinzugefügt, wobei die Beschichtung basierend auf den Silbernanodrähten präpariert wird;
Schritt 4: ein transparentes flexibles Substrat ist ein PET-Film, der gleichmäßig mit der Silbernanodrahtbeschichtung unter Verwendung eines Walzdrahtwalzverfahrens beschichtet wird, wobei die Abstände zwischen dem Draht und dem Stab 15 µm sind, und die Walzgeschwindigkeit zur Beschichtung 80 cm/min ist, wobei ein gleichmäßiger Nassfilm auf der Oberfläche des transparenten flexiblen Substrats gebildet wird;
Schritt 5: der Nassfilm, beschichtet mit der obigen Beschichtung, wird nach einem Trocknen in einem Vakuumtrockner bei 150° C für 3-10 min vollständig volatilisiert, und die flexible transparente leitfähige Elektrode wird erhalten.
le procédé de fabrication de l'électrode conductrice transparente flexible comprend les étapes suivantes:
étape 1 - 100 parties de dispersion aqueuse de nanofils d'argent, 5 à 8 parties de résine acrylique aqueuse, 2 à 5 parties de triéthylènetétramine, 0,1 à 0,3 partie d'huile de ricin hydrogénée et 30 à 40 parties d'un mélange de solvants sont toutes ajoutées dans un mélangeur sous vide où elles sont mélangées uniform-mément, démoussées sous vide, puis la solution de mélange est préparée, dans laquelle la concentration de nanofils d'argent dans la dispersion aqueuse est de 2 à 10 mg/ml et le solvant du mélange est un mélange de solvant alcoolique et de solvant cétonique;
étape 2 - 1-2 parties de p-méthylsulfonyl toluène et 0,2-0,5 parties de solution aqueuse d'alcool polyvinylique sont ajoutées dans la solution de mélange pendant le processus d'agitation. Le fluide de résine soluble dans l'eau est un fluide de résine polyester soluble dans l'eau après avoir été mélangé uniformément pendant 10 minutes d'agitation;
étape 3 - 0,2-0,4 parties d'alcanolamide et 0,3-0,5 parties d'isopropoxyéthanol sont ajoutées dans un mélangeur sous vide pour être continuellement agitées et mélangées uniformément. Le revêtement à base de nanofils d'argent est préparé;
étape 4 - le substrat flexible transparent est un film PET qui est uniformément revêtu du revêtement de nanofils d'argent en utilisant un procédé de laminage de tige de fil. Les distances entre le fil et la tige sont de 15 µmi et la vitesse de roulement pour le revêtement est de 80 cm/min, un film humide uniforme est formé sur la surface du substrat flexible transparent;
étape 5 - le film humide revêtu de l'enduit ci-dessus est complètement volatilisé après avoir été séché dans un séchoir à vide à 150° C pendant 3-10 min, et l'électrode conductrice transparente flexible est obtenue.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description