CN116031023B - Metal nanowire, extraction method thereof and transparent conductive film - Google Patents

Abstract

The invention discloses a metal nanowire, an extraction method thereof and a transparent conductive film, which can extract the metal nanowire with a desired shape from a generating solution of the metal nanowire as much as possible to prepare the transparent conductive film with excellent performance. The extraction method of the metal nanowire comprises the following steps: introducing bubbles into the liquid containing the metal nanowires to float the metal nanowires; the bubbles containing the metal nanowires floating up to the upper portion of the liquid are collected.

Description

Metal nanowire, extraction method thereof and transparent conductive film

Technical Field

The invention relates to the technical field of new materials, in particular to a metal nanowire, an extraction method thereof and a transparent conductive film.

Background

At present, metal nanowires are generally prepared by a solution method, and a protective agent such as polyvinylpyrrolidone (PVP) and a solvent such as ethylene glycol and propylene glycol are generally required to be used in the preparation process. When a transparent conductive film is produced using a production liquid from which silver nanowires are produced, solvents having high boiling points such as ethylene glycol and propylene glycol are less likely to volatilize, and thus the produced transparent conductive film is difficult to cure. In addition, the presence of a protective agent such as polyvinylpyrrolidone (PVP) may cause a change in the shape of the metal nanowires during the preparation of the transparent conductive film, and it is difficult to obtain a transparent conductive film containing the metal nanowires of a desired shape, thereby causing deterioration in the conductive performance of the conductive film.

In addition, the metal particles and the metal nanowires having a short length are simultaneously present in the liquid for producing the metal nanowires. In the transparent conductive film, metal particles and metal nanowires having a short length do not contribute to the improvement of conductivity, and also cause deterioration of transmittance and increase of haze of the transparent conductive film.

Therefore, it is necessary to extract a metal nanowire having a desired shape as much as possible from a liquid for producing a metal nanowire, and to produce a transparent conductive film.

Disclosure of Invention

The present invention provides a metal nanowire having a desired shape in a production liquid from which the metal nanowire is produced by extraction as much as possible, and a method for extracting the metal nanowire, and a transparent conductive film, wherein the metal nanowire can be used for producing a transparent conductive film having excellent performance.

In order to achieve the above object, a first aspect of the present invention provides a method for extracting a metal nanowire, the method comprising:

and introducing bubbles into the liquid containing the metal nanowires to float the metal nanowires.

The bubbles containing the metal nanowires floating up to the upper portion of the liquid are collected.

In the extraction method of the metal nanowire provided by the invention, bubbles are introduced into the liquid containing the metal nanowire, so that the metal nanowire with high length-diameter ratio is attached by the bubbles to form a relatively stable framework structure with a plurality of bubbles taking the metal nanowire as a framework, and the metal nanowire attached by the bubbles moves to the upper part of the liquid along with the floating of the bubbles in the liquid. In addition, although the metal particles and the metal nanowires having a low aspect ratio in the liquid are also attached to the bubbles, the metal nanowires having a high aspect ratio are separated from the bubbles or sink to the lower part of the liquid after being attached briefly because a stable skeleton structure cannot be formed when the metal nanowires are lifted up along with the bubbles, and therefore, the metal particles and the metal nanowires having a low aspect ratio remain in the liquid along with the bubbles, and thus, the separation and extraction of the metal nanowires having a desired shape can be realized.

Compared with the prior art, the extraction method of the metal nanowire does not generate a large amount of waste liquid because no organic solvent is added, and when the metal nanowire is extracted by adopting bubbles, the mechanical damage of the metal nanowire can be reduced, the surface performance of the obtained metal nanowire is good, and the purity of the extracted metal nanowire is higher.

The second aspect of the invention provides a metal nanowire obtained according to the extraction method of the metal nanowire.

Compared with the prior art, the metal nanowire provided by the invention has the same beneficial effects as the metal nanowire extraction method in the technical scheme, and the description is omitted here.

A third aspect of the present invention provides a transparent conductive film comprising the metal nanowire described above.

Compared with the prior art, the transparent conductive film has the same beneficial effects as the metal nanowire extraction method in the technical scheme, and the description is omitted here.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:

fig. 1 illustrates a schematic structural diagram of a metal nanowire extraction device according to the present invention;

FIG. 2 illustrates a schematic diagram of a metal nanowire extraction process in accordance with the present invention;

FIG. 3 illustrates a flow diagram of a metal nanowire extraction method in accordance with the present invention;

fig. 4 is an optical imaging diagram of a silver nanowire coating solution prepared by dark gray infusion obtained by first extraction in the first embodiment of the present invention;

FIG. 5 is an optical imaging diagram of a silver nanowire coating solution prepared from bubbles obtained by the second extraction in the first embodiment of the present invention;

FIG. 6 is an optical imaging diagram of a silver nanowire coating solution prepared by extracting the liquid remaining in the measuring cylinder for the second time in the first embodiment of the present invention;

fig. 7 is an optical imaging diagram of a silver nanowire coating solution obtained in comparative example one of the present invention.

Reference numerals:

100: a metal nanowire extraction device; 110: a blister container;

120: a collection container; 130: a bubble generator;

130-1: a gas delivery line; 130-2: a porous body.

Detailed Description

In order to clearly describe the technical solution of the embodiments of the present invention, in the embodiments of the present invention, the words "first", "second", etc. are used to distinguish the same item or similar items having substantially the same function and effect. For example, the first threshold and the second threshold are merely for distinguishing between different thresholds, and are not limited in order. It will be appreciated by those of skill in the art that the words "first," "second," and the like do not limit the amount and order of execution, and that the words "first," "second," and the like do not necessarily differ.

In the present invention, the words "exemplary" or "such as" are used to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.

In the present invention, "at least one" means one or more, and "a plurality" means two or more. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a alone, a and B together, and B alone, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b or c may represent: a, b, c, a and b, a and c, b and c, or a, b and c, wherein a, b, c can be single or multiple.

In the preparation of silver nanowires by a solution method, polyvinylpyrrolidone (PVP), ethylene glycol, propylene glycol, and the like are generally required to be added as a dispersing agent and a surface protecting agent for the metal nanowires. When the prepared metal nanowire is used as a base material of a transparent conductive film to form a film on a PET film, the drying temperature is generally below 150 ℃, and under the temperature condition, high-boiling-point solvents such as ethylene glycol and the like cannot be evaporated, so that the solvent of the base material layer is too much and cannot be concentrated, and the hardening of the transparent conductive film is not facilitated. However, polyvinylpyrrolidone (PVP) functioning as a surface protective film of the metal nanowire affects the physical properties of the transparent conductive film and the growth tendency of the silver nanowire, and therefore, the residual portion of polyvinylpyrrolidone (PVP) should be removed.

Meanwhile, metal particles with a few micrometers in the prepared metal nanowire generating solution, metal nanowires with a shorter length below a few micrometers and metal nanowires with a specified shape coexist. Since these metal particles of several micrometers and metal nanowires having a short length are responsible for deterioration of transmittance and improvement of haze in the production of transparent conductive films, it is necessary to extract metal nanowires having a predetermined shape from a metal nanowire production liquid and produce transparent conductive layers using the metal nanowires to improve the performance of transparent conductive films.

In the prior art, methods for extracting metal nanowires from a metal nanowire production solution include a centrifugal separation method, a membrane filtration method, a cross filtration method and the like. These three methods will be briefly described below using silver nanowires as an example.

The centrifugal separation method is useful for extracting silver nanowires of a predetermined shape having good conductivity, and can cause all of silver nanoparticles and short silver nanowires to precipitate. However, the precipitation requires a long time and is inefficient, and in order to reduce the viscosity of the silver nanowire production liquid to promote the precipitation, the precipitation needs to be diluted with a solvent, which is costly and not environmentally friendly. In addition, silver nanowires obtained by precipitation are entangled with each other, may not be redispersed, and a transparent conductive film prepared using the silver nanowires is poor in ambiguity and uneven in resistance distribution.

The membrane filtration method is a method of performing membrane filtration using a membrane having a small pore diameter of about 1 μm. Before the membrane filtration method is used, the silver nanowire generating solution with the silver nanowires is required to be diluted to about 10 times and subjected to membrane filtration, so that a lot of waste liquid is generated, and the environment protection is not facilitated. Although silver nano particles can be removed by using a membrane filtration method, silver nano wires are accumulated on a membrane to block small holes, and the membrane needs to be replaced frequently, so that the efficiency of extracting the silver nano wires is low. Silver nanowires stacked on the film are fused and adhered to each other, are difficult to disperse, and the transparent conductive film prepared by using the silver nanowires has poor ambiguity and uneven resistance distribution.

Silver nanoparticles can be removed by the cross filtration method, but dilution is required as in the membrane filtration method, a large amount of waste liquid is generated, and the cost is high and the environment is not protected. Silver nanowires deposited on the filter module are fused and attached to each other, so that a coagulated material which cannot be redispersed is generated, and extraction efficiency is low. Meanwhile, part of silver nanowires can be attached to a pipeline, and extraction efficiency of the silver nanowires can be affected. On this basis, the cleaning of the filter module, the cleaning of the pipeline and the like are labor-consuming.

In order to overcome the above-mentioned shortcomings, exemplary embodiments of the present invention provide a metal nanowire extraction apparatus for extracting target metal nanowires, i.e., metal nanowires of a specified shape, more efficiently and environmentally-friendly, so that a transparent conductive film prepared using the extracted metal nanowires has higher transmittance, higher conductivity, and lower ambiguity. It should be understood that the metal nanowire of the exemplary embodiment of the present invention may be a metal simple substance or an alloy nanowire such as a silver nanowire, a nickel nanowire, a copper nanowire, a platinum nanowire, a gold nanowire, etc., without being limited thereto. These metal nanowires can be used as a material of the conductive layer of the transparent conductive film, and are not limited thereto. In a liquid containing metal nanowires, the length of the metal nanowires of a predetermined shape is longer than other metal nanowires and metal particles.

Fig. 1 illustrates a schematic structural view of a metal nanowire extraction device according to an exemplary embodiment of the present invention, and fig. 2 illustrates a schematic structural view of a skeleton structure according to an exemplary embodiment of the present invention. As shown in fig. 1 and 2, the metal nanowire extraction device 100 may include: a foamer container 110, a collection container 120 and a foam generator 130. Wherein the foamer container 110 is selected from axially long containers. For example, the foamer container 110 may be a cylindrical container having an axial length of 2 to 20 times the diameter of the bottom surface. In this way, the bubbles can be ensured to move in the bubble container for a long time, under the action of gravity, the metal particles which do not form a framework structure with the bubbles and the metal nanowires with shorter lengths sink under the action of gravity, so that the effect of screening the metal particles and the metal nanowires with shorter lengths from the metal nanowires with specified shapes is realized, and the ratio of the target metal nanowires with specified shapes and long lengths in the extracted metal nanowire solution is maximized. The collection vessel 120 is used for collecting metal nanowires of a prescribed shape carried by bubbles to the upper portion of the metal nanowire-containing liquid in the bubble vessel 110, and the bubble vessel 110 is located within the collection vessel 120 during the collection process so as to collect the metal nanowires. The bubble generator 130 is used to generate bubbles having a desired particle size.

In the present embodiment, an example in which one bubble generator is used in the bubble container is shown, but the number of bubble generators is not limited, and a plurality of bubble generators may be used in the bubble container.

In practical applications, as shown in fig. 1 and 2, the bubble generator 130 may include a gas storage member (not shown) and a gas delivery pipe 130-1. The gas storage member may store gas under pressure, or may store gas under normal pressure. When the gas stored in the gas storage member is an atmospheric pressure gas, the bubble generator 130 may further include a gas pressurizer (not shown) for applying a certain pressure to the gas released from the gas storage member. At this time, the gas pressurizer may be located between the gas storage and the gas delivery line 130-1.

In order to generate bubbles having a desired particle size, as shown in fig. 1 and 2, the bubble generator 130 may further include a porous body 130-2, the porous body 130-2 being in communication with the outlet of the gas delivery pipe 130-1, and at least one small hole having a diameter being provided on the surface of the porous body 130-2 for generating bubbles having different particle sizes. The surface of the porous body 130-2 may have a plurality of pores with different diameters, and the bubbles generated by the pores with small diameters have a smaller average particle diameter, so that the bubbles with small average particle diameter are more convenient to capture the metal nanowires in the liquid containing the metal nanowires, and move in the direction of the bubbles with large average particle diameter to carry the metal nanowires, so that the metal nanowires are adsorbed by the bubbles with large average particle diameter and move to the upper part of the liquid along with the bubbles. In the moving process, as the length of the metal nanowire with a specified shape is longer, a framework structure shown in figure 2 can be formed with a plurality of bubbles, so that the metal nanowire can be stably lifted by the bubbles to move to the upper part of the liquid containing the metal nanowire. The porous body 130-2 does not react with the solute in the liquid containing the metal nanowires, and the porous body 130-2 may be selected according to the actual situation, and for example, the porous body 130-2 may be a porous ceramic, a porous volcanic glass, a film having micro-cracks formed, or the like, and is not limited thereto.

Fig. 3 illustrates a flow chart of a metal nanowire extraction method according to an exemplary embodiment of the present invention. As shown in fig. 3, the metal nanowire extraction method provided by the exemplary embodiment of the invention includes:

step 110: and introducing bubbles into the liquid containing the metal nanowires to float the metal nanowires. The bubbles in the liquid containing the metal nanowires can be pressurized bubbles, so that the bubbles can have an impulse force moving to the surface of the liquid, the moving direction of the bubbles can be guided, the bubbles are assisted to move to the upper part of the liquid containing the metal nanowires, and the extraction purity of the metal nanowires is improved. The metal nanowire floats up because the metal nanowire is adsorbed by the bubble, and moves to the upper portion of the liquid along with the movement of the bubble.

Step 120: the bubbles containing the metal nanowires floating up to the upper portion of the liquid are collected. The metal nanowires in the liquid are adsorbed on the bubbles generated in the bubble container, so that a skeleton structure as shown in fig. 2 is formed between the bubbles and the metal nanowires, in addition, the metal particles and the metal nanowires with low length-diameter ratio contained in the liquid are adhered by the bubbles, and in the moving process of the bubbles, most of the metal particles and the metal nanowires with low length-diameter ratio are temporarily adhered by the bubbles and then remain in the liquid or gradually sink, and the metal nanowires with high length-diameter ratio forming the skeleton structure with the bubbles float at the upper part of the liquid in the form of bubble groups. At this time, the ratio of the metal nanowires in the bubble group is high, and the metal nanowires can be separated from the bubble group by collecting the floating bubble group.

In practical application, when the metal nanowire is required to be used for preparing a transparent conductive film, bubble groups can be directly centrifugally separated to prepare a wet precipitate, the wet precipitate is added into a dispersion liquid containing water and methanol, and after a hydroxyethyl cellulose aqueous solution with the mass content of 1% is added, the mixture is coated on a PET film, and then the PET film is dried.

The extraction method of the metal nanowire provided by the invention has the characteristics of high efficiency and low cost. Meanwhile, when the metal nanowire is extracted by adopting bubbles, the mechanical damage of the metal nanowire can be reduced, the surface performance of the obtained metal nanowire is ensured to be good, and the purity of the extracted metal nanowire is higher.

As one possible implementation, before the liquid containing the metal nanowires according to the exemplary embodiment of the present invention is introduced into the bubbles, the liquid containing the metal nanowires may be subjected to the following treatment: adding a metal nanowire generating liquid into the bubbling water to prepare a liquid containing metal nanowires. The metal nanowire generating solution may include metal nanowires, metal nanoparticles, a protective agent, and a solvent. Illustratively, the solvent contained in the metal nanowire generating solution may be glycols, and the protective agent contained in the metal nanowire generating solution may be polyvinylpyrrolidone.

In order to improve the extraction rate of the metal nanowires, ensure that bubbles can sufficiently move in the liquid containing the metal nanowires so as to adsorb more metal nanowires, improve the extraction yield of the metal nanowires, and control the viscosity of the liquid containing the metal nanowires. Therefore, the mass percentage of the metal element contained in the metal nanowire generating liquid can be 0.01% -0.5%, so that the content of the metal nanowire is ensured to be enough, and the viscosity of the liquid containing the metal nanowire can be controlled on the basis of forming a skeleton structure. For example, the liquid containing the metal nanowires may contain 0.01% by mass of the metal element, may be 0.25% by mass, may be 0.5% by mass.

In practical application, the metal nanowires with specified shapes can be extracted by controlling the flow and the size of bubbles. It should be understood that the metal nanowire with a specified shape herein refers to a metal nanowire with an average length-diameter ratio of more than 1000, so as to ensure that a skeleton structure as shown in fig. 2 can be formed when bubbles are adsorbed on the surface of the metal nanowire, increase the adsorption stability between the metal nanowire and the bubbles, ensure that the metal nanowire can not easily fall off and sink along with the bubbles in the process of moving along with the bubbles, and the thickness and the shape of the metal nanowire are not limited herein.

The flow rate of the bubbles can be adjusted according to the size of the bubble container, and in the embodiment, the flow rate of the bubbles can be 30mL mL/min-200 mL/min, preferably 30 mL/min-100 mL/min. For example, the bubbling flow rate may be 30mL/min, 50/min, 100/min, 150/min, 200mL/min, or the like, but is not limited thereto. In order to sufficiently extract the metal nanowires in the liquid containing the metal nanowires, the time for introducing the bubbles into the liquid containing the metal nanowires may be 5min to 10min. For example, the time for bubbling the metal nanowire-containing liquid may be 5 minutes, 7 minutes, or 10 minutes. The bubbles include first bubbles and second bubbles, wherein the average particle size of the first bubbles may be 1 μm to 200 μm, and the average particle size of the second bubbles may be 1nm to 500nm. For example, the average particle diameter of the first bubbles may be 1 μm, may be 150 μm, may be 200 μm, or the like, and is not limited thereto. The average particle diameter of the second bubbles may be 1nm, 270 nm, 500nm, or the like, and is not limited thereto.

In order to ensure that the performance of the extracted metal nanowires does not change, the solubility of the gas forming the bubbles in the liquid containing the metal nanowires is less than a preset solubility, and the gas is chemically inert to the metal nanowires. When the gas is chemically inert to the metal nanowires, no chemical reaction exists between the gas and the metal nanowires, and the metal nanowires are not oxidized or vulcanized, wherein the bubbles can be nitrogen bubbles, air bubbles or hydrogen bubbles. Preferably, the bubbles may be nitrogen bubbles. It should be understood that the preset solubility herein may be set according to the solute in the actual liquid containing the metal nanowires, and is not limited herein.

In practical applications, the bubble generator may be used to foam water, and then the metal nanowire generating liquid may be added to the bubble water. When the metal nanowire generating liquid is added into the bubble water, bubbles are introduced into the liquid containing the metal nanowires from the bottom of the bubble container. When the metal nanowire generating liquid is contained in the foaming container, bubble water can be added into the metal nanowire generating liquid, and the bubble generator is placed in the foaming container, so that bubbles are introduced into the liquid containing the metal nanowires from the bottom of the container, and the bubbles can be ensured to exist in the liquid containing the metal nanowires sufficiently.

When the bubble generator comprises a gas storage piece, a gas conveying pipeline and a porous body, the gas inlet end of the gas conveying pipeline is connected with the gas storage piece, the gas outlet end of the gas conveying pipeline is connected with the porous body, and the water is positioned in the bubble container. The gas storage member sends the pressurized gas into the gas delivery pipe, and bubbles are formed after the pressurized gas is dispersed through the porous body. In order to fill as much of the air bubbles as possible in the water, the porous body may be located at the bottom of the bubble container. Meanwhile, the bubble water is utilized to dilute the metal nanowire generating liquid, so that the viscosity of the metal nanowire generating liquid can be adjusted, the bubble can float on the metal nanowire generating liquid for a long time, and the metal nanowire with a specified shape can be conveniently screened out.

It should be noted that, here, the stirring rod or the stirrer may be used to stir the solution, so that the metal nanowires, the metal particles and the metal nanowires with shorter length may be fully dispersed, so as to facilitate bubble capture, thereby improving the extraction purity of the metal nanowires.

The exemplary embodiment of the invention also provides a metal nanowire, which is obtained according to the extraction method of the metal nanowire. The average length-diameter ratio of the metal nanowires is more than 1000.

The beneficial effects of the metal nanowire provided by the exemplary embodiment of the invention are the same as those of the metal nanowire extraction method described in the technical scheme, and are not repeated here.

Exemplary embodiments of the present invention also provide a transparent conductive film including the above-described metal nanowire. In practical applications, the above metal nanowires may be used as the conductive layer of the transparent conductive film.

The beneficial effects of the transparent conductive film provided by the exemplary embodiment of the invention are the same as those of the extraction method of the metal nanowire described in the technical scheme, and are not repeated here.

The invention is further illustrated by means of the following examples, which are not intended to limit the scope of the invention. The experimental methods, in which specific conditions are not noted in the following examples, were selected according to conventional methods and conditions, or according to the commercial specifications.

Example 1

The foamer container was a measuring cylinder with a capacity of 300ml, an inner diameter of 34.5mm and an effective height of 330 mm. The collecting container is a 2L beaker made of polyethylene. The porous body is a ring-shaped ceramic tube of ceramic device of Noritake (Noritake), and has a diameter of 12mm and a length of 50mm. The average particle size of the first bubbles generated by the porous body was 153. Mu.m, and the average particle size of the second bubbles generated was 77nm. The gas is nitrogen. The metal nanowire is silver nanowire, the average grain diameter phi=30nm of the silver nanowire contained in the silver nanowire generating solution is 12 μm, the mass percent of silver in the silver nanowire generating solution is 0.3%, and the main solvent in the silver nanowire generating solution is glycol.

(1) First extraction of silver nanowires:

160ml of distilled water was poured into a 300ml measuring cylinder. A bubble generator with a gas flow rate of 95mL/min was placed in the measuring cylinder to foam distilled water. Then, the bubble generator was temporarily removed, and 40ml of the silver nanowire generation liquid was added to the measuring cylinder. After stirring uniformly, putting the mixture into a bubble generator again for foaming. At this time, the measuring cylinder was placed in a 2L polyethylene beaker to collect a bubble mass containing silver nanowires located at the upper part of the measuring cylinder. After 5 minutes, the bubbling was stopped, the liquid remaining in the measuring cylinder was transferred to another measuring cylinder, and the above operation was repeated 4 more times, and a total of 200ml of the liquid containing silver nanowires was treated to obtain a liquid with bubble clusters in a 2L polyethylene beaker and a liquid remaining in another measuring cylinder. The dark gray bubbles in the upper part of the liquid with bubble clusters in the 2L polyethylene beaker were recovered with a spatula, and white bubbles were present in the lower layer of the dark gray bubbles, taking care not to mix with the gray bubbles as much as possible, and the first extracted foaming parameters are shown in table 1.

(2) Second extraction of silver nanowires:

each time 240ml of the mixture of the liquid remaining in the recovered 2L polyethylene beaker and the liquid remaining in the other vessel was poured into a 300ml measuring cylinder, and then put into a bubble generator to foam, and when the foaming was started, the bubbles generated in the first tens of seconds were almost white, and after a period of foaming, dark gray bubbles were gradually generated. The measuring cylinder was placed in a 2L polyethylene beaker to collect the bubble mass containing silver nanowires located in the upper part of the measuring cylinder. After 3 minutes the foaming was stopped. After repeating the above operation 4 times, the liquid remaining in the measuring cylinder and the bubbles collected in the 2L polyethylene cup were obtained, and the foaming parameters of the second extraction are shown in Table 2.

(3) Manufacturing a transparent conductive film: the dark gray bubbles obtained by the first extraction, the bubbles obtained by the second extraction and the liquid remaining in the measuring cylinder after the second bubbling were separately centrifuged at 2100rpm to obtain 3 kinds of precipitates. The precipitate from the dark grey bubbles was then made into a water/methanol dispersion weighing 75g, and the precipitate from the bubbles from the second extraction and the precipitate from the liquid remaining in the measuring cylinder from the second extraction were made into a water/methanol dispersion weighing 10g, respectively. 2.125g of each obtained water/methanol dispersion was taken out, and 0.375g of 1% by mass of an aqueous solution of hydroxyethyl cellulose was added, and after stirring uniformly, the aqueous solution was applied to A4-size PET film using an application bar to a thickness of 27.5. Mu.m, and after drying, a dark gray colored clear conductive film prepared by the first extraction, a clear conductive film prepared by the second extraction, and a clear conductive film prepared by the second bubbling, respectively, from the liquid remaining in the measuring cylinder. The three silver nanowire coating liquids were observed by using a metal microscope, respectively, to obtain fig. 4 to 6. The properties of the transparent conductive films were tested using a commercially available ambiguity meter and a measuring instrument for resistance, and the specific test results are shown in table 3.

Example 2

The procedure was as in example 1, except that the gas flow rate was 60mL/min, the bubbling time for the first extraction was 7 minutes, the bubbling parameters for the first extraction were shown in Table 1, the bubbling parameters for the second extraction were shown in Table 2, and the properties of the obtained transparent conductive film were shown in Table 3.

Example 3

The procedure was as in example 1, except that the gas flow rate was 130mL/min, the bubbling time for the first extraction was 4 minutes, the bubbling parameters for the first extraction were shown in Table 1, the bubbling parameters for the second extraction were shown in Table 2, and the properties of the obtained transparent conductive film were shown in Table 3.

Example 4

The foamer container was replaced with a cylindrical container having a capacity of 1500ml, an inner diameter of 85mm and an effective height of 280 mm. In the first extraction, 800mL of distilled water was added to 200mL of the silver nanowire production liquid, and bubbling was performed at a gas flow rate of 120mL/min, and the other operations were the same as in example 1. In the second extraction, the residual liquid in the 2L polyethylene beaker after the recovery and the residual liquid in the measuring cylinder are injected into a 1500ml cylinder container, and only 1 operation is performed to obtain the residual liquid in the measuring cylinder and bubbles collected in the 2L polyethylene cup, wherein the foaming parameters of the first extraction are shown in Table 1, the foaming parameters of the second extraction are shown in Table 2, and the performance of the prepared transparent conductive film is shown in Table 3.

Table 1 comparison table of first time extracted foaming parameters

TABLE 2 comparison of foaming parameters for the second extraction

Comparative example 1

200g of silver nanowire production liquid and 200g of distilled water were mixed, and centrifugal separation was performed at a rotation speed of 2100rpm, to obtain a precipitate. In order to prevent the precipitates from fusing and adhering to each other, the supernatant was removed after standing for a certain period of time, the precipitate was taken out, the supernatant was removed after 4 hours of centrifugation, the lower precipitate was taken out, the supernatant was removed after 16 hours of centrifugation again, and the precipitate was taken out. The precipitate obtained after 3 times of centrifugation was collected to prepare a water/methanol dispersion liquid in a total amount of 75g, and a transparent conductive film was produced in the same manner as in example 1, and the properties of the produced transparent conductive film are shown in Table 3. An optical imaging diagram of the silver nanowire coating liquid on the surface of the prepared transparent conductive film is observed by using a metal microscope, and is shown in fig. 7.

Comparative example 2

200g of a silver nanowire generating solution and 200g of distilled water were mixed, and the remaining operations were the same as comparative example 2, and properties of the prepared transparent conductive film are shown in Table 3.

TABLE 3 Performance of transparent conductive films

As can be seen from comparing the properties of the transparent conductive films prepared by the dark gray infusion obtained by the first extraction in examples 1 to 4 with those of the transparent conductive films prepared by the methods of comparative examples 1 and 2, the transparent conductive films prepared by the methods of examples 1 to 4 have higher surface resistance than the transparent conductive films prepared by the methods of comparative examples 1 and 2, but have higher transmittance than the transparent conductive films prepared by the methods of comparative examples 1 and 2, lower haze than the transparent conductive films prepared by the methods of comparative examples 1 and 2, and lower haze after removal of the substrate than the transparent conductive films prepared by the methods of comparative examples 1 and 2. The transparent conductive film with excellent performance, that is, the transparent conductive film with higher silver nanowire content has low surface resistance, low ambiguity and high transmittance, so that the yield of the metal nanowires extracted by the methods of examples 1-4 is higher.

On this basis, as can be seen from fig. 4, the transparent conductive film prepared using the dark gray-colored formulation obtained by the first extraction has a large content of silver nanowires having a long length. As can be seen from fig. 5, the transparent conductive film prepared using the bubbles obtained by the second extraction has a large content of silver nanowires having a short length. As can be seen from fig. 6, the transparent conductive film prepared using the liquid remaining in the measuring cylinder after the second bubbling has a part of the silver nanowires having a short length and a large amount of silver particles. As can be seen from fig. 7, the transparent conductive film prepared by the method of comparative example 1 has a significantly longer silver nanowire content than that of fig. 4.

In summary, the silver nanowires extracted by the metal nanowire extraction method provided by the exemplary embodiment of the invention have higher yield.

Although the invention has been described herein in connection with various embodiments, other variations to the embodiments of the invention can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Although the invention has been described in connection with specific features and embodiments thereof, it will be apparent that various modifications and combinations can be made without departing from the spirit and scope of the invention. Accordingly, the specification and drawings are merely exemplary illustrations of the present invention as defined in the appended claims and are considered to cover any and all modifications, variations, combinations, or equivalents that fall within the scope of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (9)

1. The extraction method of the metal nanowire is characterized by comprising the following steps of:

adding the metal nanowire generating liquid into bubble water to obtain liquid containing metal nanowires;

introducing bubbles into the liquid containing the metal nanowires to enable the metal nanowires to float upwards;

collecting bubbles containing the metal nanowires floating to the upper part of the liquid, wherein the flow rate of the bubbles is 30 mL-200 mL/min;

the mass percentage of the metal elements contained in the metal nanowire generating liquid is 0.01% -0.5%.

2. The method according to claim 1, wherein the metal nanowire production liquid contains metal nanowires, metal nanoparticles, a protective agent, and a solvent.

3. The method of extracting metal nanowires as recited in claim 1, wherein the bubbling into the liquid containing metal nanowires to float the metal nanowires, comprises:

and extracting the metal nanowire with a specified shape by controlling the flow and the size of the bubble.

4. The method for extracting metal nanowires according to claim 1, wherein the time for introducing the bubbles into the liquid is 5min to 10min.

5. The method of extracting a metal nanowire according to claim 1, wherein the bubbles include first bubbles and second bubbles, wherein an average particle diameter of the first bubbles is 1 μm to 200 μm, and an average particle diameter of the second bubbles is 1nm to 500nm.

6. The method of claim 1, wherein the bubbles are one of nitrogen bubbles, air bubbles, and hydrogen bubbles.

7. A metal nanowire, characterized in that it is obtained by the extraction method of a metal nanowire according to any one of claims 1 to 6.

8. The metal nanowire according to claim 7, wherein the metal nanowire has an average aspect ratio of 1000 or more.

9. A transparent conductive film comprising the metal nanowire of claim 7 or 8.