TW202317674A - Transparent conductive film and manufacturing method thereof including a flexible substrate, at least one conductive layer and a fluorine-containing polyimide film - Google Patents

Abstract

The present invention discloses a transparent conductive film and a manufacturing method thereof, which include a flexible substrate, at least one conductive layer and a fluorine-containing polyimide film, herein the thickness of the flexible substrate is between 10 micro meters and 100 micro meters, the conductive layer and the fluorine-containing polyimide film are respectively formed on the surface of the flexible substrate, and the conductive layer is covered between the fluorine-containing polyimide film and the flexible substrate. The thickness of the fluorine-containing polyimide film is between 0.2 micro meter and 1 micro meters, and the fluorine-containing polyimide film comprises at least one dianhydride monomer and a product formed by condensation polymerization of at least two kinds of diamine monomers, the ratio of the total moles of the at least one dianhydride monomer to the at least two kinds of diamine monomers can be between 1 : 0.95 to 1 : 1.1. The present invention also provides a method for manufacturing the aforementioned transparent conductive film.

Description

Transparent conductive film and manufacturing method thereof

The invention relates to a conductive film, in particular to a transparent conductive film and a manufacturing method thereof.

A large number of products that require transparent electrodes, such as touch panels for tablet computers, organic light-emitting and displays, and thin-film solar energy, have always used Indium Tin Oxide (ITO) as the main transparent conductive film material. However, the output of indium is low and the price is high. Judging from the source and cost of materials, there is a need to find alternative materials. Therefore, from the 1980s to the present, the development of ITO alternative materials has continued. In addition, transparent conductive oxides (Transparent Conducting Oxide; TCO) such as ITO are basically hard materials and are not resistant to deformation or bending.

The experimental results show that when the ITO film on the PET substrate is stretched, if the elongation reaches about 3%, the ITO film layer will lose its original conductivity. All TCO materials have this essential weakness. With the rise of flexible displays in recent years, it is necessary to seek transparent conductive film materials with better bending resistance, and when the size of the panel continues to increase, the ITO film will soon face the bottleneck that the resistance can no longer be reduced, which also prompts related The industry and developers are more actively developing non-ITO transparent conductive film materials. Non-ITO (or non-TCO) transparent conductive film materials to be used in touch panels, in addition to basic sheet resistance and transmittance, must also meet other requirements, such as stability, environmental resistance (high temperature, high humidity, etc.) , Patternable, etc. In addition, they must fit into existing production lines without major modifications or additions.

Among them, metal nanowires, especially silver wires (AgNWs), are considered to be a potential material that is most likely to replace indium tin oxide for transparent conductors in the future. In addition, copper is cheaper and more abundant than silver, which can greatly reduce the cost of nanowires. Also, copper wire conducts electricity almost as well as silver wire. Therefore, the synthesis of high-quality copper wires is of great significance and has received more and more attention. However, due to the large surface area of nanowires, lack of stability and copper thermal oxidation and chemical corrosion are still a problem.

The invention provides a transparent conductive film and a manufacturing method thereof, which can produce a transparent conductive film with lower sheet resistance, better light transmittance and bending resistance.

The transparent conductive film disclosed by the present invention includes a flexible substrate, at least one conductive layer and a fluorine-containing polyimide film. Wherein, the thickness of the flexible substrate is between 10 microns and 100 microns, the conductive layer is formed on the surface of the flexible substrate, the fluorine-containing polyimide film is formed on the surface of the flexible substrate, and the conductive layer is coated on the fluorine-containing polyimide film. Between the amine film and the flexible substrate. The thickness of the fluorine-containing polyimide film is between 0.2 microns and 1 micron. The fluorine-containing polyimide film is formed by condensation polymerization of at least one dianhydride monomer and at least two diamine monomers. The total molar ratio of the anhydride monomer and the at least two diamine monomers may be between 1:0.95 and 1:1.1.

According to the manufacturing method of the transparent conductive film disclosed in the present invention, it includes the following steps:

forming at least one conductive layer on the surface of a flexible substrate, the thickness of the flexible substrate is between 10 microns and 100 microns; and

Forming a fluorine-containing polyimide film on the surface of the flexible substrate, so that the conductive layer is covered between the flexible substrate and the fluorine-containing polyimide film, the thickness of the fluorine-containing polyimide film is between 0.2 microns and 1 Between microns, the fluorine-containing polyimide film is formed by condensation polymerization of at least one dianhydride monomer and at least two diamine monomers, and the total moles of at least one dianhydride monomer and at least two diamine monomers The ratio of numbers can be between 1:0.95 and 1:1.1.

The purpose of the present invention is to improve the problems of lack of stability, thermal oxidation of copper, chemical corrosion and adhesion faced by conventional copper nanowires in the manufacture. According to the transparent conductive film disclosed in the present invention and its manufacturing method, the use Fluoropolyimide film covers the conductive layer, making it have excellent adhesion, low sheet resistance, better light transmittance and bending resistance, which can improve the current lack of stability of copper nanowires Disadvantages such as resistance, copper thermal oxidation, chemical corrosion and adhesion.

10: Flexible substrate

20: Conductive layer

30: Fluorinated polyimide film

Fig. 1 is a flow chart of the steps of the manufacturing method of the transparent conductive film of the present invention.

Figure 2 is a schematic view of the appearance of the transparent conductive film of the present invention.

Fig. 3 is a schematic diagram of the chemical structure of the fluorine-containing polyimide membrane of the present invention.

Fig. 4 is a glass transition temperature test data diagram of the present invention.

Fig. 5 is a flow chart of the steps of the manufacturing method of the fluorine-containing polyimide membrane of the present invention.

Fig. 6 is a graph showing the relationship between the resistance change rate and the number of bending cycles of the transparent conductive film of the present invention.

The implementation of the present disclosure is described below through specific examples, and those skilled in the art can understand other advantages and effects of the present disclosure from the content disclosed in this specification. This disclosure can also be implemented or applied through other different specific embodiments, and various modifications can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of this creation. with change. As used in the specification and appended claims, the singular forms "a", "the" and "the" include plural plural individuals unless the content clearly dictates otherwise. Unless otherwise stated in the text, the term "or" used in the specification and the appended claims includes the meaning of "and/or".

Please refer to "Fig. 1", "Fig. 1" is a flow chart of the steps of the manufacturing method of the transparent conductive film of the present invention, including the following steps:

Step S100: forming at least one conductive layer 20 on the surface of the flexible substrate 10, the thickness of the flexible substrate 10 is between 10 microns and 100 microns (μm);

Step S110: Form a fluorine-containing polyimide film 30 on the surface of the flexible substrate 10, so that the conductive layer 20 is coated between the flexible substrate 10 and the fluorine-containing polyimide film 30, and the fluorine-containing polyimide film The thickness of 30 is between 0.2 micron and 1 micron (μm), and the fluorine-containing polyimide film 30 is formed by condensation polymerization of at least one dianhydride monomer and at least two diamine monomers.

Please also refer to "Fig. 2", which is a schematic diagram of the appearance of the transparent conductive film of the present invention. In step S100, at least one conductive layer 20 is first formed on a flexible substrate 10. The type of the flexible substrate 10 is not particularly limited, and any substrate suitable for preparing electronic components is applicable. In a specific embodiment of the present invention, the flexible substrate 10 may include but not limited to polydimethylsiloxane (polydimethylsiloxane, PDMS), polyimide (polyimide, PI), polycarbonate (polycarbonate, PC) , polyethylene terephthalate (polyethylene terephthalate, PET), polyacrylate (polyacrylate, PA), polyethylene naphthalate (polyethylene naphthalate, PEN), polyetherimide (polyetherimide, PEI) And the above-mentioned derivatives, etc.

When the conductive layer 20 of the present invention is used in electronic equipment or electrical equipment, it may include metals such as copper or copper alloys, nickel or nickel alloys, aluminum or aluminum alloys, or alloy materials thereof. The method of forming the conductive layer 20 on the flexible substrate 10 includes but not limited to hydrothermal method (Hydrothermal method), chemical vapor deposition (for example: metalorganic chemical vapor deposition), pulsed laser deposition, molecular beam epitaxy (MBE) or electrochemical deposition. In a preferred embodiment of the present invention, the nanoparticles of copper or copper alloy can be synthesized by hydrothermal method, and then the nanoparticles of copper or copper alloy can be deposited on the flexible substrate 10 by spraying method.

In step S110, a fluorine-containing polyimide film 30 is formed on the surface of the flexible substrate 10, preferably a fluorine-containing polyimide film with fluorine atoms in the polyimide structure, so that the conductive layer 20 is wrapped between the flexible substrate 10 and the fluorine-containing polyimide film 30 , and the fluorine-containing polyimide film 30 is formed by condensation polymerization of at least one dianhydride monomer and at least two diamine monomers.

According to a preferred embodiment of the present invention, the dianhydride monomer is a monomer composed of fluorine groups. The dianhydride monomer may be at least one dianhydride monomer selected from hexafluorodianhydride (6FDA) and 4,4'-oxydiphthalic anhydride (ODPA), but is not limited thereto.

The diamine monomer contains at least one monomer containing more than one monomer selected from the group consisting of oxygen, sulfo and fluorine, and the diamine monomer can be selected from 2,2'-bis(trifluoromethane base)-4,4'-diaminobiphenyl (TFMB), 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminobenzanilide (DABA), but And it doesn't stop there.

Please refer to "Figure 3", which is a schematic diagram of the chemical structure of the fluorine-containing polyimide membrane of the present invention. Coating the polymerized fluorine-containing polyimide slurry on the surface of the conductive layer 20 can reduce the surface tension of the slurry through its fluorine-containing functional group, so as to reduce the influence of water vapor in the process environment, thereby increasing the conductivity The service life of layer 20.

In the present invention, the fluorine-containing polyimide film 30 exhibits an average light transmittance of at least 85% at an optical wavelength of 550 nm, and a glass transition temperature (Tg) of at least greater than 220° C.

As used herein, "transmittance" is defined as the transmission through a material (e.g. Percentage of incident optical power in a given optical wavelength range, such as an article, substrate, or optical film or part thereof. In addition, the "glass transition temperature" used in the present invention refers to the heat resistance of the fluorine-containing polyimide film 30, so a higher glass transition temperature is preferable. Please refer to "Figure 4", "Figure 4" is a graph showing the glass transition temperature test data of the present invention. Specifically, the glass transition temperature of the fluorine-containing polyimide film 30 of the present invention is at least higher than 220°C, and the preferred glass transition temperature may be between 220°C and 350°C.

Please refer to "Figure 5", "Figure 5" is the structural formula of the fluorine-containing polyimide membrane of the present invention, and the synthesis steps are as follows:

Step S200: performing condensation polymerization reaction of at least one dianhydride monomer and at least two diamine monomers in at least one solvent to prepare a polyamic acid solution;

Step S210: using at least one of the thermal imidization method and the chemical imidization method to complete the imidization of the polyamic acid solution to obtain a polyimide composition, and remove the polyimide composition solvent;

Step S220: coating the polyimide composition on a carrier, and curing the polyimide composition at a temperature of 80° C. to 420° C. to form a fluorine-containing polyimide film.

In step S200, the polyamic acid solution is prepared by preparing a monomer mixture of at least two kinds of dianhydride monomers and at least two kinds of diamine monomers in a substantially equimolar amount. Dissolved in an organic solvent until the above-mentioned at least one dianhydride monomer and at least two diamine monomers are condensed and polymerized, the ratio of the total moles of at least two dianhydride monomers and at least two diamine monomers It can be between 1:0.95 and 1:1.1. Usually, the polyamic acid solution is obtained with a solid content of 10% to 30%, preferably 20% to 25%. At concentrations within the above range In the case of polyamide acid solution to obtain the appropriate molecular weight and solution viscosity.

The above-mentioned solvent for synthesizing the polyamic acid solution is not particularly limited, as long as it is a solvent for dissolving the polyamic acid, preferably an amide solvent. Specifically, the above solvent may be a polar solvent, a low boiling point solvent or a low water absorption solvent. For example, it can be selected from N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO) , m-cresol, tetrahydrofuran (THF), chloroform, 3-methoxy-N, N-dimethylpropionamide and γ-butyrolactone (GBL) at least one of the group consisting of, but not They are not limited thereto, and may be used alone or in combination of two or more kinds as necessary.

However, according to the type of monomers and the desired physical properties of the polyimide film, all the monomers can be added at one time in the above step S200, or each monomer can be added sequentially. local aggregation.

The polyamic acid solution prepared through the above step S200 has a molecular structure in the form of branched chain connections with different physical properties. Physical properties of a polyimide film obtained by imidizing a polyamic acid solution, such as light transmittance, glass transition temperature, etc. are adjusted.

In step S210, a thermal imidization method, a chemical imidization method, or a combined imidization method using thermal imidization and chemical imidization methods can be used. The thermal imidization method is a method of imidizing a polyamic acid solution only by heating without using a catalyst such as a dehydrating agent. The chemical imidization method is a method of promoting imidization of a polyamic acid solution using a catalyst such as a dehydrating agent and/or an imidizing agent. The complex imidization method can be formed by adding a dehydrating agent and an imidization agent into a polyamic acid solution to form a film on a carrier, and then heat it to harden and dry.

The imidization agent refers to the effect of promoting the ring-closing reaction of polyamide acid As components, for example, aliphatic tertiary amines, aromatic tertiary amines, and heterocyclic tertiary amines are used. In the present invention, catalysts such as quinoline, isoquinoline, β-picoline, pyridine, 1-methylimidazole, 1,2-dimethylimidazole and 2-methylimidazole are preferably added to polyamide in the amine solution.

The dehydrating agent promotes the ring closure reaction by dehydrating the polyamic acid solution, such as aliphatic acid anhydride, aromatic acid anhydride, N,N'-dialkyl carbodiimide, halogenated lower aliphatic, halogenated lower Fatty acid anhydride, aryl phosphonic acid dihalide and sulfite halide or a mixture of two or more thereof. In the present invention, it is preferred to add acetic anhydride, propionic anhydride, butyric anhydride, benzoic anhydride or a mixture of two or more thereof into the polyamide acid solution.

After adding the above-mentioned imidization agent and/or dehydrating agent into the polyamic acid solution, heat it to a temperature of 60° C. to 120° C. to react, and the reaction time is between 12 hours and 24 hours to obtain a polyamic acid solution. Composition for imide. Then drop the polyamic acid composition after the reaction into the mixture of alcohol and deionized water to precipitate, and the weight ratio of alcohol and deionized water is 1:1. Finally, the precipitated polyimide composition was washed several times with alcohol, and dried at 100° C. for 24 hours.

In step S220, the composition for polyimide is spin-coated on the carrier, and the carrier includes but not limited to glass plate, aluminum foil, endless stainless steel belt or stainless steel drum. In the present invention, the polyimide composition is spin-coated on the surface of the flexible substrate 10, and then the polyimide composition is heated at a temperature of 80°C to 420°C for about 1 hour. within. In the present invention, the optimum heating temperature is between 80°C and 250°C. After that, the polyimide composition is cured and/or dried to form a fluorine-containing polyimide film 30 on the surface of the flexible substrate 10, so that the conductive layer 20 is covered with the polyimide film 30 and the flexible substrate. Between 10.

Please refer to Table 1. Table 1 is the adhesion evaluation data of the transparent conductive film of the present invention. From Table 1, the adhesion is measured according to the ASTM D3359 hundred-grid test standard. It can be known that the surface of the conductive layer is not coated with fluorine-containing polymer For the sample of imide film (w/o CPI), the conductive layer is first coated on the surface of a substrate, and then pulled and peeled off 3 times with adhesive tape, each time on the edge of the incision and the intersection of the 100-grid line on the substrate There are pieces of peeling off at the point, and the peeling area is greater than 65%, so it can be seen that the adhesion level is 0B. Compared with the sample (w/o CPI) that is not coated with the fluorine-containing polyimide film, the fluorine-containing polyimide film of the sample (300nm CPI) is also firstly coated with a conductive layer on the surface of a substrate, And cover the surface of the conductive layer with a fluorine-containing polyimide film with a thickness of 300nm, and then pull and peel it off 3 times with an adhesive tape. Adhesion rating is 5B. Similarly, the fluorine-containing polyimide film of the sample (600nm CPI) also obtained the measurement result of the adhesion level being 5B, and then the fluorine-containing polyimide film of the sample (300nm CPI) and the sample (600nm CPI) had Scratch resistance, water resistance and other effects.

Please refer to "Figure 6", "Figure 6" is a graph showing the relationship between the resistance change rate and the number of bending cycles of the transparent conductive film of the present invention. The X-axis is the number of bending cycles (N), and the Y-axis is the resistance change rate (RR ₀ )/R ₀ , where R is the resistance and R ₀ is the initial resistance. The transparent conductive film (CuNWs) of the present invention and the conventional indium tin oxide film (ITO) were respectively subjected to bending cycle tests. When the conventional indium tin oxide film (ITO) was bent 100 times, its conductivity deteriorated sharply. However, when the transparent conductive film (CuNWs) of the present invention is bent up to 500 times, its conductivity remains stable, showing that the transparent conductive film of the present invention has high stability, excellent adhesion and bending resistance.

10: Flexible substrate

20: Conductive layer

30: Fluorinated polyimide film

Claims (10)

A transparent conductive film comprising: A flexible substrate, the thickness of the flexible substrate is between 10 microns and 100 microns; At least one conductive layer is formed on the surface of the flexible substrate; and A fluorine-containing polyimide film is formed on the surface of the flexible substrate, the conductive layer is covered between the fluorine-containing polyimide film and the flexible substrate, and the thickness of the fluorine-containing polyimide film is between Between 0.2 micron and 1 micron, the fluorine-containing polyimide film is formed by condensation polymerization of at least one dianhydride monomer and at least two diamine monomers, at least one dianhydride monomer and at least two diamine monomers The ratio of the total moles of the body can be between 1:0.95 and 1:1.1. The transparent conductive film as described in Claim 1, wherein the flexible substrate can be polydimethylsiloxane (polydimethylsiloxane, PDMS), polyimide (polyimide, PI), polycarbonate (polycarbonate, PC), poly Ethylene terephthalate (polyethylene terephthalate, PET), polyacrylate (polyacrylate, PA), polyethylene naphthalate (polyethylene naphthalate, PEN), polyetherimide (polyetherimide, PEI) in more than one. The transparent conductive film as described in Claim 1, wherein the conductive layer synthesizes a copper or copper alloy nanoparticle by a hydrothermal method, and then deposits the copper or copper alloy nanoparticle on the flexible substrate by a spray method Formed on top. A method of manufacturing a transparent conductive film, comprising the following steps: Forming at least one conductive layer on the surface of a flexible substrate, the thickness of the flexible substrate is between 10 microns and 100 microns; and Forming a fluorine-containing polyimide film on the surface of the flexible substrate, so that the conductive layer is coated between the flexible substrate and the fluorine-containing polyimide film, and the thickness of the fluorine-containing polyimide film is between at 0.2 Between microns and 1 micron, the fluorine-containing polyimide film is formed by condensation polymerization of at least one dianhydride monomer and at least two diamine monomers, the at least one dianhydride monomer and the at least two diamines The ratio of total moles of monomers can be between 1:0.95 and 1:1.1. The method for manufacturing a transparent conductive film as described in claim 4, wherein the step of forming the conductive layer on the surface of the flexible substrate further includes the following steps: synthesizing a copper or copper alloy nano-particle through a hydrothermal method, and then The conductive layer is formed by depositing the copper or copper alloy nanoparticles on the surface of the flexible substrate by spraying method. The method for manufacturing a transparent conductive film as described in Claim 4, wherein the step of forming the fluorine-containing polyimide film on the surface of the flexible substrate further includes the following steps: The at least one dianhydride monomer and the at least two diamine monomers are condensed and polymerized in at least one solvent to prepare a polyamic acid solution; Using at least one of a thermal imidization method and a chemical imidization method to complete the imidation of the polyamic acid solution to obtain a polyimide composition, and remove the polyimide composition solvents; and The polyimide composition is coated on a carrier, and the polyimide composition is heat-treated at a temperature of 80° C. to 420° C. to solidify into a fluorine-containing polyimide film. The method for manufacturing a transparent conductive film as described in Claim 6, wherein the solvent can be selected from N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), N,N-dimethyl Dimethylformamide (DMF), dimethylsulfoxide (DMSO), m-cresol, tetrahydrofuran (THF), chloroform, 3-methoxy-N, N-dimethylpropionamide and γ-butyrolactone At least one of the group consisting of (GBL). The manufacturing method of the transparent conductive thin film according to claim 6, wherein the optimum film-forming temperature of the fluorine-containing polyimide film is between 80°C and 250°C. The method for manufacturing a transparent conductive film as described in Claim 4, wherein the dianhydride monomer is one or more selected from hexafluorodianhydride (6FDA) and 4,4'-oxydiphthalic anhydride (ODPA) . The manufacturing method of the transparent conductive film as described in Claim 4, wherein the diamine monomer is selected from 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 4 , more than one of 4'-diaminodiphenyl ether (ODA), 4,4'-diaminobenzoanilide (DABA)

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