Luo Nannan et al. through the technical decomposition of carbon nanotubes and graphene conductive film materials in the transparent conductive film of carbon materials, they are mainly divided into product improvement, preparation method improvement and application, and the product improvement and preparation method improvement are further detailed. According to the number of patent applications, the main improvement directions are summarized. At the same time, the important and cutting-edge patent applications are sorted out and displayed, which will help domestic applicants have a more comprehensive understanding of the technical development of carbon nanotubes and graphene-based conductive films.

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Technical evolution of patent application for carbon nanotube conductive film

1.1 Improvement of carbon nanotube conductive film method

(1) Preparation method

①Substrate CVD method

Nagoya University and Toray Corporation disclosed in JP 2006-298713A that a carbon source is in contact with a solid-supported transition metal catalyst, and a three-layer structure of carbon nanotubes is formed on the substrate in an orthogonal direction. The metal has an average diameter. Metal particles smaller than 10 nanometers. William Marsh Rice University discloses a method for preparing vertical single-walled carbon nanotubes by hot filament chemical vapor deposition in US20120145997A1. A catalyst is placed on the surface of the substrate on which carbon nanotubes are grown, and is in gaseous contact with hydrogen and gaseous hydrocarbons in the reaction chamber. , The heating temperature exceeds 2000°C, the activated gas, and the vertical single-walled carbon nanotubes grow on the substrate.

②Floating catalytic gas phase CVD method

The Institute of Industrial Technology Integration, an independent administrative legal person, disclosed in CN101707904A the use of flowing vapor CVD to realize large-scale preparation of single-walled carbon nanotube films at low temperatures.

The Institute of Metal Research of the Chinese Academy of Sciences disclosed in CN107527673A that in the floating catalytic gas phase CVD method, by reducing the concentration of the catalyst and the carbon source and the residence time in the constant temperature zone, part of the carbon source decomposed by the catalyst forms an SP2 carbon island, which is welded to a single The intersections between the single-walled carbon nanotubes form a single-walled carbon nanotube film with SP2 carbon island welding structure. The obtained conductive film has a light transmittance of 90%, and the sheet resistance is only 41Ω/sq.

③ Arc discharge method

Sony Corporation discloses in CN101683976A that lanthanide metal oxides, transition metals, or a mixture of nickel and rare earth elements are used as catalysts, and selenium, tellurium, or germanium or combinations thereof are used as promoters by arc discharge method Carbon nanotubes are produced from carbon sources. The method can efficiently prepare carbon nanotubes with high purity and narrow diameter distribution.

Toyo Tanso Co., Ltd. discloses in CN101631744A that a halogen-treated carbon source and a raw material of a metal catalyst are used as an anode, and a carbon material containing carbon nanotubes is prepared by an arc discharge method.

(2) Film forming method

① Coating and filming

The key of the coating film forming method is to solve the dispersibility of the carbon nanotubes in the solution, and to coat the carbon nanotube dispersion liquid on the substrate to form a film. This type of patent application improvement points overlap with the carbon nanotube dispersion part, so the carbon nanotube dispersion part will be emphatically listed.

②Spray forming film

Tianjin University of Technology discloses in CN104021879A a method for preparing a flexible transparent conductive film of carbon nanotubes with strong adhesion. The PET substrate of ethylene terephthalate is immersed in nitric acid, washed with water and dried in sequence. The PET heating plate is sprayed at low speed and heated at high speed to produce FTCFs.

③Electrodeposition film formation

The Institute of Metal Research of the Chinese Academy of Sciences discloses in CN101654784A a preparation method and an electrodeposition device for flexible carbon nanotube transparent conductive film materials. An anionic surfactant such as C10-C16 alkyl sulfate is dispersed in an aqueous solution under the action of ultrasonic to obtain a plating solution, and a carbon nanotube film is obtained by electrodeposition.

1.2 Improvement of carbon nanotube conductive film products

(1) Carbon nanotube composite/composite film

Nano silver wires, carbon materials, and conductive polymers (PEDOT:PSS) are currently the most potential ITO alternative materials. These three types of materials have different advantages and disadvantages. PEDOT: PSS film has low conductivity and poor stability; nano silver wire film has poor light transmittance and haze; carbon materials have poor dispersion and high surface roughness. The combined use of these three types of materials can make up for their shortcomings.

① Carbon nanotube and metal composite conductive film

Kuraray Co., Ltd. discloses a composite conductive film of carbon nanotubes and nano silver wires in WO2009035059A1. A conductive grid made of silver nanowires is distributed in the conductive layer containing carbon nanotubes.

Tsinghua University and Hongfujin Precision Industry (Shenzhen) Co., Ltd. disclosed a composite structure of carbon nanotubes and porous metal in CN109019563A, which mechanically fixes nanotubes on the surface of the porous composite metal.

②Carbon nanotube and metal oxide composite conductive film

Kyung Hee University disclosed in KR2011032468A that the composite carbon nanotube conductive film on the ITO transparent conductive film helps to improve the brittleness of the ITO conductive film.

The Korean Academy of Machinery and Materials Science disclosed in WO2011145797A1 that single-walled carbon nanotubes are embedded in metal oxides to form a composite conductive film. The metal oxide and stabilizer are dissolved in ethanol to form a metal oxide sol-gel solution, single-walled carbon nanotubes are added, dispersed uniformly, and a film is formed on the substrate to obtain a composite conductive film, which can be used as the N-type of organic solar cells Conductive layer.

③ Carbon nanotube and polymer composite film

Arkema France et al. disclosed a composition containing carbon nanotubes and an electrolyte (co)polymer in WO2015063417A2.

The National Advanced Industrial Science and Technology Research Center discloses in JP2017130276A a conductive film prepared from a dispersion containing a conductive polymer with oxidation or reduction properties, carbon nanotubes, and an ionic liquid.

(2) Carbon nanotube dispersion

Carbon nanotubes have poor solubility and are easy to aggregate. Solving their dispersibility in conductive films is a technical difficulty and the key to determining whether they can be used as excellent conductive film materials.

(3) Carbon nanotube conductive ink/ink

Tsinghua University and Hongfujin Precision Industry (Shenzhen) Co., Ltd. disclosed conductive inks containing carbon nanotubes in CN102093774, including: carbon nanotubes with hydrophilic groups on the surface, flake graphite, organic carriers, and binders , Dispersant, film enhancer and solvent, the conductive ink can directly form a conductive film on the surface of the substrate.

Biooni Co., Ltd. discloses in WO2015005665A1 a ceramic paste composition that can be used to prepare a conductive film. The ceramic paste composition includes carbon nanotubes or carbon nanotube-metal composites and a silicon binder, and the ceramic paste composition has the characteristics of low surface resistance.

(4) Modification/modification of carbon nanotubes

In JP2012124107A, Sony Corporation mixed and dispersed carbon nanotubes with hydrophilic groups and a hydrophilic conductive polymer in a solvent to obtain a composite dispersion of carbon nanotubes and conductive polymers.

The Korea Institute of Science and Technology discloses a method for polymer-modified carbon nanotubes in US20100084007A1. The polymer TEMPO-PSSNa and carbon nanotubes are connected by chemical bonds to obtain modified carbon nanotubes MWNT-g-PSSNa, which improves the dispersibility of carbon nanotubes.

(5) Carbon nanotube aggregates

Beijing Funat Innovation Technology Co., Ltd. discloses in CN103373718A a carbon nanotube film with high light transmittance, which includes a plurality of carbon nanotubes and a plurality of carbon nanotube clusters, and the plurality of carbon nanotube clusters pass through the A plurality of carbon nanotube wires are spaced apart, and a plurality of carbon nanotube clusters between adjacent carbon nanotube wires are spaced apart.

Sony Corporation discloses a carbon nanotube conductive material in JP2009295378A, in which a plurality of carbon nanotubes are stacked two-dimensionally and partially in contact with each other.

Source: Summary of patents on carbon nanotubes and graphene conductive transparent film materials

Luo Nannan, Wang Zhuo, Gao Xiaozhen, Yue Ruijuan
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