KR101788634B1 - Method for Producing Carbon NanoTube Fiber - Google Patents

Abstract

A method for producing a carbon nanotube fiber according to the present invention, as a post-treatment process of a carbon nanotube fiber, comprises the following steps: preparing carbon nanotube fibers; coating the carbon nanotube fibers with a silicone emulsion; winding the emulsion-coated carbon nanotube fibers; coating a polymer solution containing polyvinyl alcohol and glutaraldehyde on the wound carbon nanotube fibers and sizing the carbon nanotube fibers; and drying the sizing-treated carbon nanotube fibers. The carbon nanotube fibers produced by the steps have excellent properties such as tensile strength, heat resistance and the like as compared with conventional carbon nanotube fibers, and can maintain existing excellent electric conductivity to be applied to the next generation of new technologies and new materials such as wearable devices, electric/electronic and bio fields.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing carbon nanotube fibers,

The present invention relates to a process for producing carbon nanotube fibers, and more particularly to a process for post-treatment of carbon nanotube continuous fibers having excellent tensile strength and heat resistance.

Carbon nanotubes (CNTs), which have rounded curves in the shape of hexagonal rings, have a tensile strength 100 times stronger than steel, a current density 1000 times higher than copper, and diamonds and thermal conduction It is a material with very good properties similar to those of the glass. Such carbon nanotubes have various mechanical and electrical properties depending on the arrangement of the hexagonal rings constituting the carbon nanotubes and the number of walls, and the physical properties of the individual carbon nanotubes are not limited to those of commercialized high-functional fibers such as carbon fibers, kevlar, And is applied to transparent electrodes, composite materials and the like. The fibrous carbon nanotube aggregate, that is, the carbon nanotube fibers existing in a continuous phase rather than the particle type like the individual carbon nanotubes, has no problems such as the difficulty of dispersion of the carbon nanotubes in the form of particles, Or a two-dimensional fabric, and can be utilized in various ways. Also, the density is 9 times smaller than that of carbon fiber, which is very effective for making light and strong materials like lightweight composite materials. However, despite these merits, the carbon nanotube fiber has a disadvantage that it can not express the physical properties of the individual carbon nanotubes constituting it.

From the viewpoint of mechanical properties, the carbon nanotube fibers are present in a continuous fibrous form of individual carbon nanotubes, but when the fibers are subjected to a tensile force, the carbon nanotubes are easily broken without effectively dispersing the load. This is because the surface of the carbon nanotubes is smooth and chemically inert and weak van der Waals forces act between the individual carbon nanotubes. In order to solve these problems, it is necessary to study a method of producing a high-quality fiber by changing the conditions for manufacturing the carbon nanotube fiber, that is, the spinning method, the kind and content of the carbon supply material and the synthesis temperature of the carbon nanotube, Researches are under way to improve the mechanical, electrical and thermal properties through post-treatment.

In the case of conductive fibers based on nano-carbon materials such as carbon nanotubes, as well as various problems such as the poor conductivity and low tensile strength of the metal conductive film or the conductive polymer coating, they have high physical conductivity and high tensile strength And is recognized as an ideal material for implementing electronic devices in the form of fibers or fabrics, and is attracting attention as a next-generation functional fiber that can be used in wearable smart clothing, textile display, energy storage, and sensors. The method of mass production of carbon nanotube fibers can be roughly divided into direct spinning and wet spinning. Direct spinning is a dry process technology that can produce carbon nanotube fibers in a short time by proceeding from synthesis of carbon nanotubes to fiberization. In wet spinning, powdered carbon nanotubes are dispersed in superacid without adding binder, It is a method of manufacturing fibers through a spinning technique.

The physical properties of the carbon nanotube fibers, which are formed by gathering the carbon nanotubes having a length from the micrometer to the millimeter, are low compared to the properties of the individual carbon nanotubes. Therefore, it is necessary to improve the physical properties of carbon nanotube fibers. In order to improve the properties of carbon nanotube fibers, it is necessary to develop a technique for removing amorphous carbon from the surface of carbon nanotubes during the synthesis process. That is, it is necessary to be able to effectively remove amorphous carbon and impurities during a synthesis process or a post-treatment process. In order to realize the carbon nanotube fibers in the form of a fabric, the friction coefficient of the carbon nanotube fibers should be reduced to improve suitability in processes such as weaving and forming.

Korean Patent Publication No. 10-2014-0062239 Korean Patent Publication No. 10-2012-0090383

Accordingly, it is an object of the present invention to provide a method for producing carbon nanotube fibers having excellent physical properties through a post-treatment process for improving electrical conductivity and tensile strength of carbon nanotube fibers.

According to an aspect of the present invention, there is provided a method of manufacturing a carbon nanotube fiber, comprising the steps of: a) preparing a carbon nanotube fiber; b) coating the carbon nanotube fibers with a silicone oil; c) winding the emulsion-coated carbon nanotube fibers; d) coating the wound carbon nanotube fibers with a polymer solution containing polyvinyl alcohol and glutaraldehyde, followed by sizing; And e) drying the sized carbon nanotube fibers.

In one embodiment of the present invention, the carbon nanotube fibers are prepared by spinning carbon nanotubes in the step a).

In one embodiment of the present invention, the yarn is characterized in that 10 strands of fibrous carbon nanotubes are stranded at 50 TPM.

In one embodiment of the present invention, the emulsion is contained in the DI water solvent in the step b) in an amount of 1 to 10% by weight.

In one embodiment of the present invention, the step (c) further includes a step of re-spanning after winding the wound carbon nanotube fibers after the winding.

In an embodiment of the present invention, the step (c) further includes a step of removing the emulsion after the re-weaving and drying the emulsion.

In one embodiment of the present invention, the mass ratio of polyvinyl alcohol: glutaraldehyde contained in the polymer solution is 1: 0.002.

Further, carbon nanotube fibers according to another aspect of the present invention can be produced according to the above method.

As described above, the carbon nanotube fibers produced according to the present invention have excellent physical properties such as tensile strength and heat resistance as compared with the conventional carbon nanotube fibers, and the excellent electrical conductivity is maintained. Thus, wearable devices, It can be applied to the next generation of new technology and new material creation.

FIG. 1 is a schematic view showing a method of manufacturing carbon nanotube fibers according to an embodiment of the present invention.
2 is a photograph showing SEM measurement results of carbon nanotube fibers produced according to an embodiment of the present invention.
3 is a graph comparing TGA measurement results of carbon nanotube fibers produced by the silicone emulsion and non-silicone emulsion treatment of the present invention.
4 is a graph showing a TGA measurement result of the carbon nanotube fiber produced according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

The term " step "or" step of ~ " used throughout the specification does not mean "step for. Throughout this specification, the terms "A and / or B" mean "A or B, or A and B ".

Throughout this specification, the term "combination thereof" included in the expression of the machine form means one or more combinations or combinations selected from the group consisting of the constituents described in the expression of the machine form, And the like.

The present invention relates to a process for producing carbon nanotube fibers, and more particularly to a process for post-treatment of carbon nanotube continuous fibers having excellent tensile strength and heat resistance. According to the present invention, since amorphous carbon is contained on the surface of the existing carbon nanotube fiber, the physical properties of the carbon nanotube fiber are deteriorated. Therefore, the amorphous carbon is removed through the emulsion treatment to improve the heat resistance and then the emulsion is removed again. It is possible to manufacture carbon nanotube fibers which increase the tensile strength while maintaining the excellent electrical conductivity.

In the present invention, it was confirmed that the heat-treated fiber was improved in the emulsion-treated fiber, and a polymer coating solution which produced an acetylation reaction by mixing polyvinyl alcohol (PVA) and glutaraldehyde (GA) Then, the coated CNT fiber was prepared by coating the carbon nanotube fiber. As a result of evaluating the physical properties of the thus-produced fibers, it was confirmed that the tensile strength was superior to that of the conventional carbon nanotube fibers, and the excellent electrical conductivity of the existing carbon nanotube fibers was maintained even when coating with the electrically insulating polymer solution there was.

Hereinafter, the present invention will be described in detail.

According to an embodiment of the present invention, there is provided a method of manufacturing a carbon nanotube fiber, comprising the steps of: a) preparing a carbon nanotube fiber; b) coating the carbon nanotube fibers with a silicone oil; c) winding the emulsion-coated carbon nanotube fibers; d) coating the wound carbon nanotube fibers with a polymer solution containing polyvinyl alcohol and glutaraldehyde, followed by sizing; And e) drying the sized carbon nanotube fibers.

The step a) is a step of preparing carbon nanotubes. First, an aggregate of individual carbon nanotubes is prepared. The aggregate of carbon nanotubes is not limited as long as it has a one-dimensional shape or a two-dimensional shape, and is an aggregate consisting of a set of individual carbon nanotubes. The carbon nanotubes are not particularly limited as long as the carbons connected in the form of a hexagonal ring are rolled into a nanometer-sized diameter and formed into a long barrel shape. The carbon nanotubes may have various mechanical and electrical properties depending on the arrangement of the hexagonal rings constituting the carbon nanotubes and the number of walls. In addition, the carbon nanotubes may further include a step of spinning for fiberization and then folding for improvement of tensile strength. According to one embodiment of the present invention, the carbon nanotube aggregate is fiberized by spinning, and then 10 tensile fibers of fibrous carbon nanotubes are stretched at 50 TPM to obtain a more improved tensile strength.

Next, step b) is a step of coating the flocked carbon nanotube fibers with a silicone oil emulsion. The silicone emulsion is used to remove amorphous carbon on the surface of carbon nanotube fibers to improve physical properties and increase heat resistance. A commercially available silicone emulsion was generally used. The silicone emulsion is used in a mixed solvent of DI water and 1 to 10 wt% of the deionized water solvent mixture.

Next, in step c), the emulsion-treated fiber may be wound to remove surface impurities. In addition, the wound carbon nanotube fiber may be wound and re-juxtaposed to form carbon nanotube fibers Can be improved. In addition, the step c) may further include a step of removing the emulsion after the re-squeezing and drying the emulsion, thereby solving the problem that the coating may be unevenly dispersed by the emulsion in the polymer solution coating step , And deionized water used as a solvent in emulsion coating can be removed.

Thereafter, in step d), the wound carbon nanotube fiber is coated with a polymer solution containing polyvinyl alcohol and glutaraldehyde, followed by sizing treatment. The polymer solution was prepared by mixing polyvinyl alcohol and glutaraldehyde. After dissolving in deionized water (DI water) using polyvinyl alcohol as a solvent for 4 hours to 5 hours at 80 ° C, glutaraldehyde was added. As the ratio of polyvinyl alcohol, which is an electrically conductive polymer, is increased, there is a problem of decreasing conductivity, and as the proportion of glutaraldehyde is increased, viscosity may increase and problems may occur in the coating process. Therefore, the mass ratio of polyvinyl alcohol: glutaraldehyde contained in the polymer solution may preferably be in the range of 1: 0.002.

Finally, step (e) is a step of drying the carbon nanotube fibers that have been subjected to the sizing treatment by coating the polymer solution, and it is preferable to leave them at 100 ° C for 20 minutes and dry them. If the drying temperature and the treatment time of the polymer solution are out of the above range, the deionized water used as a solvent may not be removed.

The present invention relates to a process for producing carbon nanotube fibers suitable for actual use by enhancing the properties of the carbon nanotube fibers that have been previously spun by a post-treatment process, and the carbon nanotube fibers produced according to the present invention include silicone- High heat resistance due to processing and excellent electrical conductivity, and excellent tensile strength due to post treatment of polymer solution. The present invention also relates to a method of removing amorphous carbon generated on the surface of carbon nanotube fibers through a post-treatment process of carbon nanotube fibers and improving physical properties through polymer coating, After the emulsion treatment, the physical properties were improved through the winding, marine and yarn processes applied to the other fibers. After the emulsion was removed for the polymer coating treatment, the physical properties were improved through the polymer coating treatment. This post treatment process is expected to greatly improve the mechanical properties such as tensile strength and elastic modulus and maintain the existing high electrical conductivity, which will affect the application and commercialization of carbon nanotube fibers.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for illustrating the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

Example  One

Existing carbon nanotube fibers prepared by spinning and spun carbon nanotubes were coated for 20 seconds with a solution containing 1 wt% of a silicone emulsion (BENESOL DN-01, ICEI allotment) in a solvent, and then subjected to a load of 138 g Followed by drying at 100 DEG C for 20 minutes. Next, the carbon nanotube fibers were wound, and the wound carbon nanotube fibers were subjected to a marine treatment after the marine treatment. Thereafter, the silicone-based tanning agent-coated carbon nanotube fibers were soaked in 0.5 g / L of a soaping agent for removing silicone emulsions and Na ₂ CO ₃ 1.0 g / L was added, and the mixture was kept at 70 ° C to 90 ° C for 15 minutes to remove the emulsion, followed by thorough drying at 100 ° C for 5 hours or more.

Next, 2.63 g of polyvinyl alcohol was added to 50 ml of deionized water (DI water), and the mixture was sterilized at 80 ° C for 4 hours. After changing into a viscous solution, 0.0053 ml of glutaraldehyde was added and the mixture was stood for a predetermined time to prepare a polymer coating solution .

The tanned carbon nanotube fibers were immersed in the prepared polymer coating solution for about 20 seconds and then spun for 30 seconds at a constant weight of 138 g and dried at 100 ° C for about 20 minutes to prepare carbon nanotube fibers Respectively. 2 (a) is a photograph showing SEM measurement results of the carbon nanotube fibers produced by the above process.

Example  2

Existing carbon nanotube fibers prepared by spinning and spun carbon nanotubes were coated with a silicone-based emulsion (BENESOL DN-01, ICEI allotment) in a solution containing 10 wt% in a solvent for 20 seconds and then subjected to a load of 138 g Followed by drying at 100 DEG C for 20 minutes. Next, the carbon nanotube fibers were wound, and the wound carbon nanotube fibers were subjected to a marine treatment after the marine treatment. Thereafter, the silicone-based tanning agent-coated carbon nanotube fibers were soaked in 0.5 g / L of a soaping agent for removing silicone emulsions and Na ₂ CO ₃ 1.0 g / L was added, and the mixture was kept at 70 ° C to 90 ° C for 15 minutes to remove the emulsion, followed by thorough drying at 100 ° C for 5 hours or more.

Next, 2.63 g of polyvinyl alcohol was added to 50 ml of deionized water (DI water), and the mixture was sterilized at 80 ° C for 4 hours. After changing into a viscous solution, 0.0053 ml of glutaraldehyde was added and the mixture was stood for a predetermined time to prepare a polymer coating solution .

The tanned carbon nanotube fibers were immersed in the prepared polymer coating solution for about 20 seconds and then spun for 30 seconds at a constant weight of 138 g and dried at 100 ° C for about 20 minutes to prepare carbon nanotube fibers Respectively. FIG. 2 (b) is a photograph showing SEM measurement results of carbon nanotube fibers produced by the above process.

Example  3

Existing carbon nanotube fibers prepared by spinning and spun carbon nanotubes were coated with a solution containing 1 wt% of silicone emulsion (BENESOL DN-02, ICEI allotment) in a solvent for 20 seconds and then subjected to a load of 138 g Followed by drying at 100 DEG C for 20 minutes. Next, the carbon nanotube fibers were wound, and the wound carbon nanotube fibers were subjected to a marine treatment after the marine treatment. Thereafter, the silicone-based tanning agent-coated carbon nanotube fibers were soaked in 0.5 g / L of a soaping agent for removing silicone emulsions and Na ₂ CO ₃ 1.0 g / L was added, and the mixture was kept at 70 ° C to 90 ° C for 15 minutes to remove the emulsion, followed by thorough drying at 100 ° C for 5 hours or more.

Next, 2.63 g of polyvinyl alcohol was added to 50 ml of deionized water (DI water), and the mixture was sterilized at 80 ° C for 4 hours. After changing into a viscous solution, 0.0053 ml of glutaraldehyde was added and the mixture was stood for a predetermined time to prepare a polymer coating solution .

The tanned carbon nanotube fibers were immersed in the prepared polymer coating solution for about 20 seconds and then spun for 30 seconds at a constant weight of 138 g and dried at 100 ° C for about 20 minutes to prepare carbon nanotube fibers Respectively. 2 (c) is a photograph showing SEM measurement results of the carbon nanotube fibers produced by the above process.

Example  4

Existing carbon nanotube fibers prepared by spinning and spun carbon nanotubes were coated with a silicone-based emulsion (BENESOL DN-02, ICEI allotment) in a solution containing 10 wt% of solvent for 20 seconds and then subjected to a load of 138 g Followed by drying at 100 DEG C for 20 minutes. Next, the carbon nanotube fibers were wound, and the wound carbon nanotube fibers were subjected to a marine treatment after the marine treatment. Thereafter, the silicone-based tanning agent-coated carbon nanotube fibers were soaked in 0.5 g / L of a soaping agent for removing silicone emulsions and Na ₂ CO ₃ 1.0 g / L was added, and the mixture was kept at 70 ° C to 90 ° C for 15 minutes to remove the emulsion, followed by thorough drying at 100 ° C for 5 hours or more.

Next, 2.63 g of polyvinyl alcohol was added to 50 ml of deionized water (DI water), and the mixture was sterilized at 80 ° C for 4 hours. After changing into a viscous solution, 0.0053 ml of glutaraldehyde was added and the mixture was stood for a predetermined time to prepare a polymer coating solution .

The tanned carbon nanotube fibers were immersed in the prepared polymer coating solution for about 20 seconds and then spun for 30 seconds at a constant weight of 138 g and dried at 100 ° C for about 20 minutes to prepare carbon nanotube fibers Respectively. FIG. 2 (d) is a photograph showing SEM measurement results of carbon nanotube fibers produced by the above process.

compare Example

Prepared carbon nanotube fibers prepared by spinning and spun carbon nanotubes. Next, five kinds of solutions containing 10 wt% of silicone type emulsions 1 and 2 and non-silicone type emulsions 1, 2 and 3 were prepared, respectively. Then, the prepared carbon nanotube fibers were immersed in 5 kinds of silicone- Coated with carbon nanotubes for 20 seconds and then sprayed for 30 seconds with a constant weight of 138 g and dried at 100 ° C for 20 minutes to prepare five kinds of emulsion coated carbon nanotube fibers. Then, each of the emulsion coated carbon nanotube fibers was wound, and the wound carbon nanotube fibers were subjected to a marine treatment after the marine treatment. Each of the carbon nanotube fibers coated with the emulsion was then coated with 0.5 g / L of a soaping agent for removing emulsions and Na ₂ CO ₃ 1.0 g / L was added, and the mixture was kept at 70 ° C to 90 ° C for 15 minutes to remove the emulsion, followed by thorough drying at 100 ° C for 5 hours or more.

The silicone emulsions 1 and 2 (Si 01 and 02) and the non-silicone emulsions 1 and 2 and 3 (Non-Si 01, 02 and 03) have the specifications shown in Table 1 below.

product name BENESOL DN-01
(Si 01) BENESOL DN-02
(Si 02) MP-602
(Non-Si 01) Use of Sanja
(Non-Si 02) General use
(Non-Si 03) Analysis item Average size Average size Average size Average size Average size Appearance (25 ℃) Blue colored fungus Blue liquid Yellow transparent liquid Yellow liquid Yellow liquid pH (neat) 5.76 5 6.83 8 7.5 Specific Gravity (25 ℃) 0.996 0.997 1,000 0.9 0.91 Viscosity (25 ° C, CPS) 17.1 - 160 30 65 HB-43 (105 DEG C, 40 min, 2 g) 18.38 18.5 - - -

Next, 2.63 g of polyvinyl alcohol was added to 50 ml of deionized water (DI water), and the mixture was sterilized at 80 ° C for 4 hours. After changing into a viscous solution, 0.0053 ml of glutaraldehyde was added and the mixture was stood for a predetermined time to prepare a polymer coating solution .

Each of the carbon nanotube fibers was immersed in the prepared polymer coating solution for about 20 seconds and then subjected to a constant weight of 138 g for 30 seconds and then dried at 100 ° C. for about 20 minutes to obtain five types of carbon Nanotube fiber samples were prepared.

FIG. 3 is a graph comparing TGA measurement results of carbon nanotube fibers produced by the silicone emulsion and the non-silicone emulsion treatment according to the above process. As shown in FIG. 3, in the case of coating with a non-silicone-based emulsion, the mass loss rapidly increases from around 400 ° C. However, in the case of the tanonannotube fibers prepared by coating with a silicone emulsion, It can be seen that the carbon nanotube fibers produced using the silicone emulsion are superior to the non-silicone emulsion in heat resistance.

Experimental Example : Evaluation of Properties of Carbon Nanotube Fibers

The properties of the carbon nanotube fibers produced according to Example 4 were evaluated.

The silicone emulsions used in Examples 1 to 4 had the specifications shown in Table 2 below, and the change in heat resistance after the treatment with the silicone emulsion was evaluated by using two kinds of silicone emulsions (DN-01, DN- 02, ICEI allele) were divided into 1% concentration and 10% concentration in DI water, respectively, and TGA measurement was performed. The results are shown in FIG.

product name BENESOL DN-01 BENESOL DN-02 Analysis item standard Average size standard Average size Appearance (25 ℃) Blue colored fungus Blue colored fungus Blue liquid Blue liquid pH (neat) 5.5 to 6.5 5.76 4.0 to 6.0 5 Specific Gravity (25 ℃) 0.993 to 1.003 0.996 0.988 to 1.008 0.997 Viscosity (25 ° C, CPS) 10.0 to 25.0 17.1 - - HB-43 (105 DEG C, 40 min, 2 g) 18.0 to 19.0 18.38 17.5 to 19.5 18.5

Referring to FIG. 4, in the case of general carbon nanotube fibers not treated with an emulsion, the mass loss due to the temperature increase rapidly increases from around 600 ° C., but the carbon nano- The tube fiber is reduced to a relatively gentle curve in mass loss due to the temperature increase even at a temperature of 600 ° C or higher, and the heat resistance is improved as compared with a general carbon nanotube.

In addition, tensile strength changes of the polymer-treated carbon nanotube fibers prepared according to Examples 1 to 4 were measured, and the results are shown in Table 3 in comparison with pure polymerized carbon nanotube fibers.

Maximum tensile load (N) Tensile strength (N / mm ^{2 )} thickness Pure CNT fiber 0.91 45 142.0 Examples 1 to 4 1.63 163 117.2

Referring to Table 3, when the polymer solution containing polyvinyl alcohol and glutaraldehyde is coated and sized according to the above Examples 1 to 4, the tensile strength at a thinner thickness than the pure carbon nanotube fibers .

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (8)

As a post-treatment process of carbon nanotube fibers,
a) preparing carbon nanotube fibers;
b) coating the carbon nanotube fibers with a silicone oil;
c) winding the emulsion-coated carbon nanotube fibers;
d) delaminating the wound carbon nanotube fibers after re-sintering;
e) coating and sizing the resynthesized carbon nanotube fibers with a polymer solution containing polyvinyl alcohol and glutaraldehyde; And
f) drying the sizing treated carbon nanotube fibers. The method according to claim 1,
Wherein the carbon nanotube fibers are prepared by spinning carbon nanotubes in the step a). 3. The method of claim 2,
Wherein the strand is fiber stranded with 10 TPM of 10 carbon nanotubes. The method according to claim 1,
Wherein the emulsion is contained in a DI water solvent in an amount of 1 to 10% by weight in the step b). delete The method according to claim 1,
Wherein the step d) further comprises a step of removing the emulsion after re-sintering and drying the emulsion. The method according to claim 1,
Wherein the mass ratio of polyvinyl alcohol: glutaraldehyde contained in the polymer solution is 1: 0.002. A carbon nanotube produced by the method of any one of claims 1 to 4, 6, and 7

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