WO2022137950A1 - Modified carbon nanotube forest, carbon nanotube aligned aggregate, gas-permeable sheet, catalyst electrode for fuel cells, electroconductive member, thread-like electroconductive member, interlayer heat-conductive material, and method for producing modified carbon nanotube forest - Google Patents

Abstract

The purpose of the present invention is to provide: a modified CNT forest in which a CNT forest is modified with another substance; a CNT aligned aggregate which comprises a spun product of the modified CNT forest; a gas-permeable sheet which comprises the CNT aligned aggregate; a catalyst electrode for fuel cells, which is provided with the gas-permeable sheet; an electroconductive member and a thread-like electroconductive member, each of which comprises the modified CNT forest or the CNT aligned aggregate; an interlayer heat-conductive material which comprises the electroconductive member; and a method for producing the modified CNT forest.　The modified carbon nanotube forest (40) according to the present invention comprises carbon nanotubes (50) that are aligned in a predetermined direction and microparticles (70) supported on the carbon nanotubes (50), can be spun, and preferably has a ratio R of 3 or more, in which the ratio R is defined by formula (1) below using an adjacent gap distance D1 between the carbon nanotubes (50) and an average particle diameter D2 of the microparticles (70). It is preferred that the microparticles (70) have electroconductivity.　(1): R = D1/D2 The adjacent gap distance D1 is expressed by formula (2) using the number density A (unit: carbon nanotubes/m2) of the modified carbon nanotube forest (40) and the average diameter D3 of the carbon nanotubes (50).　(2): D1 = A^-1/2-D3

Description

Method for manufacturing modified carbon nanotube forest, carbon nanotube continuum, gas permeable sheet, catalyst electrode of fuel cell, conductive member, filamentous conductive member, interlayer heat conductive material, and modified carbon nanotube forest.

The present invention provides a modified carbon nanotube forest (modified CNT forest), a carbon nanotube continuum (CNT continuum) including a spun body of the modified CNT forest, a gas permeable sheet including the CNT continuum, and the gas permeable sheet. The present invention relates to a catalyst electrode of a fuel cell, a conductive member and a filamentous conductive member including the modified CNT forest or the CNT continuum, an interlayer heat conductive material having the conductive member, and a method for producing the modified CNT forest.

As used herein, the term "CNT forest" refers to a synthetic structure of a plurality of carbon nanotubes (CNTs) (hereinafter, the individual shapes of CNTs that give such a synthetic structure are referred to as "primary structure", and the above synthetic structure is referred to as "secondary structure". It is a kind of "next structure"), and a direction in which a plurality of CNTs are in a certain direction for at least a part of the long axis direction (as a specific example, a direction substantially parallel to one normal of the surface of the substrate). It means an aggregate of CNTs that grows so as to orient in the above.). Patent Document 1 and Non-Patent Document 1 disclose a method for producing a CNT forest using iron chloride (gas phase catalyst method). Non-Patent Document 2 discloses a method (solid phase catalyst method) in which catalyst fine particles are provided on a substrate and CNTs are grown from the catalyst fine particles to obtain a CNT forest.

Further, in the present specification, a plurality of CNTs are continuously withdrawn from the CNT forest by pinching a part of the CNTs in the CNT forest and pulling the CNTs away from the CNT forest (in the present specification, this CNTs are continuously extracted from the CNT forest. The work is also referred to as "spinning" following the work of manufacturing yarn from fibers according to the prior art.) A structure having a structure in which a plurality of CNTs are connected to each other along the spinning direction is a "CNT continuum". ". Patent Document 2 discloses a secondary structure in which a plurality of CNTs have a continuous filamentous overall shape (this CNT continuum is referred to as "CNT yarn" in the present specification). The CNTs constituting the CNT yarn are oriented along the extending direction (corresponding to the spinning direction) of the CNT yarn. Further, Patent Document 2 discloses a secondary structure in which a plurality of CNTs continuously have a web-like overall shape (this CNT continuum is referred to as "CNT web" in the present specification). The CNTs constituting the CNT web are oriented along one of the in-plane directions (corresponding to the spinning direction) of the CNT web. FIG. 29 is a diagram showing a state in which CNT webs are spun from a CNT forest produced by a gas phase catalyst method.

Patent Document 3 describes a plurality of carbon fibers extending along a extending direction, the plurality of carbon fibers in which each carbon fiber contains a carbon nanotube, and a plurality of metal particles supported on the plurality of carbon fibers. A carbon nanotube electrode comprising the plurality of metal particles dispersed in the entire carbon fiber in the extending direction and electrically connecting each carbon fiber to another carbon fiber. Is disclosed.

Patent Document 4 describes a metal composite carbon nanotube twisted yarn obtained by twisting metal-walled nanotube fibers in which metal is adhered to the surface of carbon nanotube fibers in which the ends of a plurality of carbon nanotubes are bonded to each other. Disclosed is a metal composite carbon nanotube twisted yarn having a structure in which contact portions between metals adhered to nanotube fibers are fused.

Japanese Unexamined Patent Publication No. 2009-196873 Japanese Patent No. 5664832 Japanese Unexamined Patent Publication No. 2020-102352 Japanese Unexamined Patent Publication No. 2018-53408

The present invention relates to a modified CNT forest in which the CNT forest is modified with another substance, a CNT continuum having a spun body of the modified CNT forest, a gas permeable sheet having the CNT continuum, and a fuel having the gas permeable sheet. Provided are a catalyst electrode of a battery, a conductive member and a filamentous conductive member provided with the modified CNT forest or CNT continuum described above, an interlayer heat conductive material provided with the conductive member, and a method for producing the modified CNT forest described above. The purpose.

In order to solve the above problems, the provided invention includes the following aspects.
[1] A modified carbon nanotube forest comprising carbon nanotubes oriented in a predetermined direction and fine particles supported on the carbon nanotubes, which can be spun.

[2] The modified carbon nanotube forest according to the above [1], wherein the ratio R defined by the following formula (1) is 3 or more using the adjacent gap D1 of the carbon nanotubes and the average particle size D2 of the fine particles. ..
R = D1 / D2 (1)
Here, the adjacent gap D1 is represented by the following formula (2) using the number density A (unit: book / m ² ) of the modified carbon nanotube forest and the average diameter D3 of the carbon nanotubes, and the average grain. The diameter D2 and the average diameter D3 are the arithmetic average of the diameters of the fine particles in 10 or more places and the arithmetic of the diameters of the carbon nanotubes in 10 places or more, respectively, measured by observing the modified carbon nanotube forest with an electronic microscope. It is an average.
D1 = A- ^{1 / 2} -D3 (2)

[3] The modified carbon nanotube forest according to the above [1] or the above [2], wherein the fine particles have conductivity.

[4] The modified carbon nanotube forest according to any one of the above [1] to [3], wherein the fine particles contain an oxide.

[5] A carbon nanotube continuum comprising a spun body of the modified carbon nanotube forest according to any one of the above [1] to [4].

[6] The carbon nanotube continuum according to the above [5], wherein the carbon nanotube continuum has a web shape.

[7] The carbon nanotube continuum according to the above [5], wherein the carbon nanotube continuum has a thread shape.

[8] The carbon nanotube continuum according to the above [7], which is twisted.

[9] The carbon nanotube continuum having the web shape according to the above [6] is provided, and at least a part of the carbon nanotubes constituting the carbon nanotube continuum has a gap in a direction intersecting the orientation direction thereof. A gas permeable sheet characterized by being adjacent to each other.

[10] The gas permeable sheet according to the above [9], wherein the carbon nanotubes carry fine particles containing one or more elements selected from the group consisting of Pt and Co.

[11] A catalyst electrode of a fuel cell provided with the gas permeable sheet according to the above [9] or the above [10].

[12] It is characterized by comprising the modified carbon nanotube forest according to any one of the above [1] to [3] and a plating-based material deposited on the carbon nanotubes located inside the modified carbon nanotube forest. Conductive member.

[13] An interlayer heat conductive material comprising the conductive member according to the above [12].

[14] The carbon nanotube continuum according to any one of the above [5] to [8] and a plating substance deposited on the carbon nanotubes located inside the carbon nanotube continuum are provided. Conductive member.

[15] The conductive member according to the above [14], wherein the carbon nanotubes of the carbon nanotube continuum carry fine particles having conductivity.

[16] The method for producing a modified carbon nanotube forest according to any one of the above [1] to [4], wherein the metal element-containing substance is supplied to the carbon nanotube forest in a gas phase state and contains the metal element. A method for producing a modified carbon nanotube forest, which comprises decomposing a substance to generate a metal-based substance and supporting fine particles formed from the metal-based substance on the carbon nanotube forest.

[17] A filament having a carbon nanotube continuum having a thread shape according to the above [6] or [7] and a plating-based substance deposited on at least a part of the carbon nanotubes constituting the carbon nanotube continuum. Conductive member.

[18] The filamentous conductive member according to the above [17], which has a current capacity of ¹⁰⁵ A / cm ² or more.

[19] The above-mentioned [17] or the above-mentioned [18], wherein the temperature coefficient of resistance in the range of 300K to ^450K is 1.8 × 10 -3K ^-1 or less when the conductivity in the longitudinal direction is measured. Thread-like conductive member.

[20] The thread shape according to any one of the above [17] to the above [19], wherein the specific conductivity calculated based on the conductivity measured in the longitudinal direction is 400 K or more and higher than the specific conductivity of the copper wire. Conductive member.

[21] The tensile strength is 1.0 times or more and the Young's modulus is 1.5 times or more based on the blank carbon nanotube continuum corresponding to the material obtained by removing the plating-based substance from the filamentous conductive member. The filamentous conductive member according to any one of the above [17] to the above [20].

According to the present invention, a modified CNT forest, a CNT continuum including a spun body of the modified CNT forest, a gas permeable sheet including the CNT continuum, a catalyst electrode of a fuel cell including the gas permeable sheet, and the above-mentioned modified CNT forest. Alternatively, a conductive member and a filamentous conductive member provided with a CNT continuum, an interlayer heat conductive material provided with the conductive member, and a method for producing the above-mentioned modified CNT forest are provided.

It is a figure which conceptually shows an example of the manufacturing apparatus which obtains a modified CNT forest from a CNT forest. It is a figure which shows the observation result of a part of the side surface of a CNT forest. It is a figure which shows the observation result of a part of the side surface of a modified CNT forest. It is a partially enlarged view of FIG. It is a figure which shows the result of observing the side surface shown in FIG. 4 by the backscattered electron image. It is a figure which shows the observation result of the part of the cross section obtained by removing a part of the CNT forest. It is a figure which shows the result of observing the side surface shown in FIG. 6 by the backscattered electron image. It is a figure which conceptually shows how the modified CNT forest is spun. (A) A diagram showing how a CNT twisted yarn is produced by twisting a CNT yarn obtained by spinning a modified CNT forest, and (b) a diagram conceptually showing a configuration of an apparatus for spinning a modified CNT forest. Is. It is a figure which shows the observation result of the CNT plying. It is a partially enlarged view of FIG. (A) An observation view of a cross section of a CNT twisted yarn, and (b) a view of a central portion of the cross section of FIG. 12 (a) partially enlarged and observed by backscattered electrons. It is a figure which conceptually showed the structure of the apparatus which plating the CNT plying by the electroplating of the copper sulfate bath. It is a figure which shows the observation result of the modified CNT forest. It is a figure which shows the observation result of the modified CNT forest. It is a figure which shows the observation result of the modified CNT forest. It is a figure which shows the observation result of the modified CNT forest. It is a histogram which shows the measurement result of the particle diameter of a fine particle. It is an observation view of the appearance of a conductive member. It is an enlarged observation view of the conductive member of FIG. FIG. 3 is an observation diagram showing a cross section of a conductive member produced including plating with a current density of 5 mA / cm ² . It is an observation view which shows the cross section of the comparative conductive member manufactured without modification with copper fine particles. (A) An observation view showing a cross section of a conductive member produced including plating with a current density of 4 mA / cm ² , (b) a partially enlarged central portion of the cross section of FIG. 23 (a). It is an observed figure. It is an observation view which shows the cross section of the comparative conductive member without modification with copper fine particles. It is a graph which shows the measurement result of the conductivity (unit: S / cm) of a conductive member. It is a graph which shows the measurement result of the specific conductivity (unit: S · m ² · kg ^-1 ) of a conductive member. It is a graph which shows the measurement result of the current capacity (unit: A / cm ² ) of a conductive member. It is a graph which shows the measurement result of the specific current capacity (unit: A · cm · kg ^-1 ) of a conductive member. It is a figure which shows the state which the CNT web was spun from the CNT forest produced by the gas phase catalyst method. It is a figure which shows the secondary electron image of the CNT forest which carried the copper nanoparticles, which was produced with the amount of Cu (acac) ₂ used as 10 mg. It is a figure which shows the secondary electron image of the CNT forest which carried the copper nanoparticles, which was produced with the amount of Cu (acac) ₂ used as 30 mg. It is a figure which shows the secondary electron image of the CNT forest which carried the copper nanoparticles, which was produced with the amount of Cu (acac) ₂ used as 100 mg. It is a figure which shows the cross-sectional secondary electron image of the composite yarn which had copper deposited on the CNT twisted yarn which supported Cu-NPs. It is a figure which shows the cross-section secondary electron image of the composite yarn which had copper deposited on the CNT twisted yarn which does not support Cu-NPs. It is a figure which shows the transmission electron image of the orthogonal cross section of the composite yarn which had copper deposited on the CNT twisted yarn which supported Cu-NPs. It is a figure which shows the high magnification image of FIG. 32 (A). It is a figure which shows the transmission electron image of the parallel cross section of the composite yarn which had copper deposited on the CNT twisted yarn which carried Cu-NPs. It is a figure which shows the high magnification image of FIG. 33 (A). It is a graph which shows the conductivity of the composite yarn which deposited copper in the CNT plying which supported Cu-NPs, and the composite yarn which deposited copper in the CNT twisted yarn which did not support Cu-NPs. FIG. 34 (A) is a graph in which the vertical axis is a linear scale. It is a graph which shows the temperature dependence of the electrical resistivity which standardized the electrical resistivity of each sample by the value at 300K. It is a graph which shows the temperature dependence of the specific conductivity of a composite yarn which had copper deposited on the CNT twisted yarn which carried Cu—NPs, and a copper wire. It is a graph which shows the current capacity of each sample. It is a graph which shows the relationship between the specific conductivity and the specific current capacity of each sample. It is a stress-strain diagram of each sample. It is a graph which shows the relationship between Young's modulus and tensile strength of various samples. It is a figure which shows the secondary electron image of the tensile fracture part of the composite yarn which had copper deposited on the CNT twisted yarn which supported Cu-NPs. It is a figure which shows the secondary electron image of the tensile fracture part of the composite yarn which had copper deposited on the CNT twisted yarn which does not support Cu-NPs. It is a figure which shows the secondary electron image of the composite yarn which had copper deposited on the CNT twisted yarn which supported Cu-NPs. It is a figure which shows the secondary electron image of the buckling part of the composite yarn which had copper deposited on the CNT twisted yarn which does not support Cu-NPs.

Hereinafter, embodiments of the present invention will be described.

The modified CNT forest (modified carbon nanotube forest) according to the embodiment of the present invention includes a CNT forest having CNTs oriented in a predetermined direction and fine particles supported on the CNTs, and can be spun. The CNT forest can be produced by the production method disclosed in Patent Document 1 and Non-Patent Document 1 (gas phase catalyst method), or the production method disclosed in Non-Patent Document 2 (solid phase catalyst method). In these cases, the predetermined direction is the direction along the normal direction of the CNT forest forming surface of the substrate for forming the CNT forest.

The modified CNT forest has a ratio R of 3 or more defined by the following formula (1) using the adjacent gap D1 of the CNT and the average particle size D2 of the fine particles.
R = D1 / D2 (1)

Here, the adjacent gap D1 is represented by the following formula (2) by the number density A (unit: book / m ² ) of the modified CNT forest and the average diameter D3 of the CNT. The average particle size D2 and the average diameter D3 are the arithmetic mean of the diameters of 10 or more fine particles and the arithmetic mean of the diameters of 10 or more carbon nanotubes measured by observing the modified CNT forest from the side with an electron microscope, respectively. It is an average.
D1 = A- ^{1 / 2} -D3 (2)

The adjacent gap D1 of the modified CNT forest can be substantially equal to the adjacent gap D1'of the CNT forest (D1 = D1') if the method for supporting the fine particles is appropriately set. As described in Non-Patent Document 1, the adjacent gap D1'of the CNT forest produced by the gas phase catalyst method has a number density A of about 10 ¹³ lines / m ² and an average diameter D3 of about 40 nm. Therefore, it is about 275 nm. On the other hand, as described in Non-Patent Document 2, the adjacent gap D1'of the CNT forest produced by the solid phase catalyst method has a number density A of about 1.5 × 10 ¹⁵ lines / m ² and an average diameter. Since D3 is about 7 nm, it is about 20 nm. In the solid phase catalyst method, a CNT forest having a number density A of about 5 × 10 ¹⁵ lines / m ² and an average diameter D3 of about 4 nm can be produced, so that the adjacent gap D1'can be set to about 10 nm. It is possible.

It is important that the average particle size D2 of the fine particles is sufficiently smaller than the adjacent gap D1 from the viewpoint of stably ensuring the spinnability of the modified CNT forest. Specifically, the ratio R defined by the above formula (1) is preferably 3 or more, more preferably 6 or more, further preferably 7 or more, and 8 or more. It is particularly preferable, and 9 or more is extremely preferable. When the average particle size D2 is large, it is highly possible that fine particles are present in the modified CNT forest so as to connect the adjacent CNTs between the adjacent CNTs in the direction intersecting the orientation direction. CNTs arranged next to each other should be separated when they are spun, but when fine particles connect adjacent CNTs as described above, it becomes difficult for CNTs arranged next to each other to separate. It may cause spinning defects.

As described above, based on Non-Patent Document 1, since the adjacent gap D1'of the CNT forest produced by the gas phase catalyst method is about 275 nm, the modified CNT formed from the CNT forest produced by the gas phase catalyst method. The average particle size D2 of the fine particles carried by the CNTs of the forest has a ratio R of 3 or more when it is 90 nm or less. Further, based on Non-Patent Document 2, since the adjacent gap D1'of the CNT forest produced by the gas phase catalyst method is about 20 nm, the modified CNT forest formed from the CNT forest produced by the gas phase catalyst method. The average diameter D2 of the fine particles carried by the CNTs is 6.7 nm or less, and the ratio R is 3 or more. In the vapor phase catalyst method, it is possible to produce a CNT forest having an adjacent gap D1'about 10 nm. In this case, the ratio R is 3 or more when the average particle size D2 of the fine particles is 3.3 nm or less.

The fine particles carried by the CNTs of the modified CNT forest may have conductivity. A typical example of conductive fine particles is that they are made of a metallic material. When the fine particles are made of a metal-based material, the constituent metal elements are not particularly limited. Examples thereof include Au, Ag, Cu, Pt, Ni, Co, Fe, Al, Ti, Zn, W, Cr and the like.

The fine particles carried by the CNTs of the modified CNT forest may contain oxides. Specific examples of the oxide contained in the fine particles include an aluminum oxide and a titanium oxide. There may be a plurality of metal elements constituting the oxide contained in the fine particles.

In the modified CNT forest according to the embodiment of the present invention, fine particles of a predetermined size can be carried on the CNT of the CNT forest which is one of the raw materials, and the obtained modified CNT forest has spinnability. If it is included, it may be manufactured by any manufacturing method. According to the method described below, the modified CNT forest can be efficiently produced.

In the method for producing a modified CNT forest according to an embodiment of the present invention, a metal element-containing substance is supplied to the CNT forest in a gas phase state, the metal element-containing substance is decomposed to generate a metal base substance, and the metal base substance is produced. It is provided that the fine particles formed from the above are supported on the CNT forest.

The CNT forest can be produced by a known method. Specific examples include the production method by the gas phase catalyst method described in Patent Document 1 and Non-Patent Document 1, and the solid phase catalyst method described in Non-Patent Document 2. The CNT forest produced by these production methods can be spun.

The metal element-containing substance is a substance that can be decomposed in the gas phase state and can form fine particles from the metal-based substance that is a decomposition product. Examples of the metal element-containing substance include organic metal complexes such as copper (II) acetylacetonate and platinum acetylacetonate, and metal halides.

The metal element-containing substance does not have to be a gas phase at the supply stage, and may be preferably a solid phase or a liquid phase from the viewpoint of improving handleability. In this case, in order to bring the metal element-containing substance into a gas phase state, it may be preferable to heat the metal element-containing substance or reduce the pressure in the space where the metal element-containing substance is arranged. Decomposition of metal element-containing substances occurs by applying energy from the outside. Specifically, the metal element-containing substance may be heated, the metal element-containing substance may be irradiated with a laser, or a high-energy ray such as an electron beam may be irradiated.

The metal-based substance, which is a decomposition product of the metal element-containing substance, may be composed of a metal-based material including an alloy and an intermetallic compound, or may be composed of an oxide. Fine particles are formed by agglomerating the produced metal-based substance or functioning as an autocatalytic reaction.

FIG. 1 is a diagram conceptually showing an example of a manufacturing apparatus for obtaining a modified CNT forest from a CNT forest. The manufacturing apparatus 100 includes a glass tube 10 whose inside is a reaction chamber RC and a heater 20 provided so as to cover the side surface of the glass tube 10. A metal element-containing substance RS is arranged in the reaction chamber RC and contains a metal element. A CNT forest 30 is arranged around the material RS.

The reaction chamber RC is depressurized and heated by the heater 20 to bring the metal element-containing substance RS into a gas phase state. The metal element-containing substance RS in the gas phase is diffused and supplied to the CNT forest 30, the metal element-containing substance RS is thermally decomposed to generate a metal-based substance, and the fine particles based on the metal-based substance are CNT forest 30. The modified CNT forest 40 is obtained by being carried by the CNTs of the above.

The particle size of the fine particles can be adjusted by the amount of the metal element-containing substance RS arranged in the reaction chamber RC, the total pressure of the reaction chamber RC, the temperature of the reaction chamber RC, and the like. The specific numerical range of these parameters is appropriately set according to the type of the metal element-containing substance RS so that the average particle size D2 set by the adjacent gap D1 of the modified CNT forest can be realized. By adjusting these parameters, it is also possible to set the loading density of the CNT fine particles.

In the production method according to the present embodiment, in order to supply the metal element-containing substance, which is the raw material of the fine particles, to the carbon nanotube forest in a gas phase state, the modification of CNTs with the fine particles is uniform with respect to the CNTs constituting the CNT forest. Can be raised high. That is, according to the manufacturing method according to the present embodiment, the CNTs located inside the CNT forest can be stably modified with fine particles, and the obtained modified CNT forest has spinning potential. can. On the other hand, for example, in Patent Document 2, Ag nanometal ink is dropped onto the CNT forest when the carbon nanotube electrode is manufactured. Therefore, among the CNTs constituting the CNT forest, more fine particles (Ag in Patent Document 2) adhere to the CNTs located on the outer side, and the fine particles are less likely to adhere to the CNTs located inside the CNT forest. Further, in the method disclosed in Patent Document 2, a liquid (ink) is dropped onto the CNT forest in order to attach fine particles to the CNTs constituting the CNT forest. At this time, the CNTs constituting the CNT forest come into contact with each other due to the cohesive force of the liquid. It is no longer possible to separate because of the strong interaction between the CNTs in contact with each other. That is, the modified CNT forest according to Patent Document 2 cannot have spinning potential.

FIG. 2 is a diagram showing the observation results of a part of the side surface of the CNT forest. Hereinafter, "observation" without mention means observation with an electron microscope or observation with an optical microscope. FIG. 2 is a secondary electron image. This CNT forest is produced by a vapor phase catalyst method, and its number density A is about 10 ¹³ lines / m ² , and the average diameter D3 of CNTs is about 35 nm. Therefore, the adjacent gap D1 of the CNT forest is about 280 nm. FIG. 3 is a diagram showing the observation results of a part of the side surface of the modified CNT forest formed from the CNT forest manufactured by the same manufacturing method as the CNT forest of FIG. FIG. 4 is a partially enlarged view of FIG.

As shown in FIG. 3, the CNTs in the CNT forest do not change morphologically even if they carry fine particles. Therefore, the adjacent gap D1 of the modified CNT forest is substantially equal to the adjacent gap D1'of the CNT forest. Since the modified CNT forest shown in FIG. 3 is formed from the CNT forest produced by the gas phase catalyst method, the adjacent gap D1 thereof is about 280 nm. Further, as shown in FIG. 4, the diameter of the fine particles supported on the CNT is sufficiently smaller than 100 nm. As will be described later in the examples, the average particle size D2 of the fine particles is 29.2 nm. Therefore, in the modified CNT forest shown in FIG. 4, the ratio R is 9 or more, and it can be said that the modified CNT forest has particularly stable spinnability.

FIG. 5 is a diagram showing the results of observing the side surface shown in FIG. 3 by a backscattered electron image, and fine particles (consisting of a Cu-based conductive substance) adhering to CNTs are observed as bright spots. FIG. 6 is a diagram showing observation results of a part of a cross section (that is, the inside of the CNT forest) obtained by removing a part of the CNT forest on the surface including the orientation direction of the CNT. FIG. 7 is a diagram showing the results of observing the side surface shown in FIG. 6 by a backscattered electron image, and the fine particles attached to the CNTs are observed as bright spots. Comparing FIGS. 5 and 7, the density of bright spots is slightly higher in FIG. 5, but a sufficient number of bright spots are also observed in FIG. 7, and the modified CNT forest is the CNT located inside the CNTs. It is confirmed that the particles are also carried.

The carbon nanotube continuum (CNT continuum) according to the embodiment of the present invention includes the spun body of the above-mentioned modified CNT forest. FIG. 8 is a diagram conceptually showing how a modified CNT forest is spun. By pulling out the CNTs 50 located on a part of the side surface of the modified CNT forest 40 on the substrate SB in the direction D, the CNTs 50 oriented in the direction D (spinning direction) are continuously connected to form the CNT continuum 60. .. As shown in FIG. 8, the fine particles 70 attached to the CNTs 50 constituting the modified CNT forest 40 maintain their state even when they are spun. Therefore, the CNTs 50 constituting the CNT continuum 60 obtained by spinning the modified CNT forest 40 are also highly uniformly modified by the fine particles 70.

The shape of the CNT continuum is determined by the spinning process. The shape may have a web shape or a thread shape.

A CNT continuum with a web shape (CNT web) is obtained by pulling out one of the sides of the modified CNT forest so that it does not converge. The drawn CNT web can be continuously spun, for example, by winding it on a drum.

The CNTs that make up the CNT web are oriented along the spinning direction. The connected state of adjacent CNTs in the spinning direction (that is, the orientation direction) is held by the van der Waals force generated between the CNTs and the other CNTs at each end. Therefore, the CNTs constituting the CNT web are not connected to the CNTs adjacent to each other in the direction intersecting the spinning direction (intersection direction) in the portion other than the end portion thereof, and the CNTs adjacent to each other in the intersecting direction are not connected to each other. There is a gap. That is, the CNT web has a mesh-like structure while the CNTs constituting the CNT web are modified from the fine particles. The length of this gap depends on the number density of the CNT forest and the spinning method (particularly the tension at the time of spinning), but can be set in the range of several nm to several μm, for example. Therefore, by appropriately adjusting the gaps in the CNT web, it is possible to form a gas permeable sheet that allows gas to pass through but does not allow liquid to pass through.

In this gas permeable sheet, since the CNTs constituting the sheet are modified with fine particles, it is possible to cause an interaction between the gas passing through the sheet and the fine particles. Moreover, the gas permeable sheet has in-plane conductivity. Specifically, based on the fact that the CNTs are oriented in the spinning direction, the conductivity along the orientation direction is higher than the conductivity in the direction orthogonal to the orientation direction. Therefore, if an appropriate conductive catalyst material (for example, a Pt-Co alloy containing Pt and Co) is set as the fine particles for modifying CNT, this gas permeable sheet can be used as a component of the catalyst electrode of the fuel cell. Is possible.

The thread-shaped CNT continuum (CNT yarn) pulls the CNTs from one of the sides of the modified CNT forest so that the CNT webs are formed, and the CNT webs are converged in the spinning direction to further pull out the CNTs. can get. The CNTs constituting the CNT yarn thus formed are oriented along the extending direction of the thread shape of the CNT yarn. Therefore, for example, the CNT yarn produced by the production method according to the present embodiment has a thread-shaped extension as compared with a thread-like structure produced by ejecting a liquid material containing CNT having a short shaft length from a die. It has high conductivity along the existing direction and has excellent mechanical properties.

As described above, since the modified CNT forest is also modified with fine particles for the CNTs located inside the modified CNT forest, the CNT yarn is modified with fine particles up to the CNTs located in the center thereof. On the other hand, for example, in the manufacturing method disclosed in Patent Document 3, a dispersion liquid containing metal particles is applied to CNT fibers (corresponding to CNT yarn) drawn from a CNT array (corresponding to CNT forest). This causes the metal particles to adhere to the CNTs. Therefore, the CNTs located on the outer side of the CNT fiber are more likely to have metal particles attached, and the CNTs located in the central portion of the CNT fiber are less likely to have metal particles attached. That is, the CNT yarn produced by the production method according to the present embodiment is more uniformly modified with fine particles than the CNT yarn produced by the production method disclosed in Patent Document 3.

The CNT yarn obtained by spinning may be wound on the bobbin as it is, or may be wound while additional processing. One of the additional work is twisting. FIG. 9A is a diagram showing a state in which a twisted yarn (CNT twisted yarn) is produced by twisting a CNT yarn obtained by spinning a modified CNT forest. FIG. 9B is a diagram conceptually showing the configuration of an apparatus for spinning a modified CNT forest. FIG. 10 is a diagram showing observation results of CNT plying, and FIG. 11 is a partially enlarged view of FIG. 10. FIG. 12A is an observation view of a cross section of the CNT twisted yarn. FIG. 12 (b) is a diagram in which the central portion of the cross section of FIG. 12 (a) is partially enlarged and observed by backscattered electrons. By twisting, the mechanical strength of the CNT yarn is increased, and the electrical characteristics (conductivity) may be further improved. As shown in FIGS. 11 and 12, the CNT plying yarn is modified with fine particles up to the CNT located at the center thereof.

In the method for manufacturing a conductive member according to an embodiment of the present invention, a CNT continuum having CNTs carrying fine particles having conductivity as described above is plated, and the CNTs located inside the CNT continuum are plated. Prepare to deposit material.

The process for depositing the plating substance may be electroplating or electroless plating. The plating substance is appropriately set as necessary. An unrestricted example of the plating process is electroplating with a copper sulfate bath. FIG. 13 is a diagram conceptually showing the configuration of an apparatus for plating CNT plying by electroplating a copper sulfate bath. In the plating apparatus 100A shown in FIG. 13, the CNT twisted yarn 120 held by the mica sheet (mica foil) 110 is immersed in the copper sulfate bath 130, and one end of the CNT twisted yarn 120 not immersed in the copper sulfate bath 130 is clipped 141. The wiring 151 connected to the clip 141 is electrically connected to the cathode terminal 161 of the power supply 160. An anode 170 made of a U-shaped copper foil is immersed in a copper sulfate bath 130, a part of the anode 170 not immersed in the copper sulfate bath 130 is sandwiched between clips 142, and a wiring 152 connected to the clip 142 is connected. It is electrically connected to the anode terminal 162 of the power supply 160. By passing a current from the power supply 160, the CNT plying 120 is copper-plated to obtain the conductive member 200.

The conductive member thus obtained has sufficiently high conductivity as it is, but the plating substance is reduced by heat-treating the conductive member in a reducing atmosphere to further enhance the conductivity of the conductive member. Can be done. The heat treatment conditions are appropriately set, and by way of example without limitation, it is 1 hour at 700 ° C. under a hydrogen stream (100 sccm).

The conductive member according to another embodiment of the present invention includes the above-mentioned modified CNT forest and a plating substance deposited on carbon nanotubes located inside the modified carbon nanotube forest. As described above, since the CNTs constituting the modified CNT forest carry the fine particles generated based on the decomposition of the metal element-containing substance, the modified CNT forest is also modified with the fine particles of the CNTs located inside the modified CNT forest. Therefore, by plating the modified CNT forest, the plating material is deposited so as to fill the gaps in the CNT forest. If the fine particles supported on the CNTs have conductivity, the deposition of the plating substance is realized more stably. If, for example, copper having high thermal conductivity is selected as the plating substance, the conductive member obtained by plating has high thermal conductivity in the extending direction of CNT, and therefore can be suitably used as an interlayer heat conductive material. ..

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.
(Example 1)

The conductive member was manufactured using the manufacturing apparatus shown in FIG. 1 and the plating apparatus shown in FIG.

By the manufacturing method shown in Patent Document 1 and the like, a CNT forest having a growth height of about 0.8 mm was obtained on the CNT forming surface of the substrate under the following conditions.
-Carbon source: Acetylene-Catalyst: Solid FeCl ₂

The CNTs constituting the obtained CNT forest had a diameter of 30 nm to 40 nm. When the CNT formation surface on the substrate after removing the CNT forest was observed, the number density of the CNT forest was about 10 ¹³ lines / m ² . When the crystallinity of the CNTs constituting the CNT forest was evaluated by Raman scattering measurement, the ratio IG / ID of the _G peak intensity of the graphene in-plane vibration mode and the _D peak intensity caused by the disorder vibration was 2 to 3. there were.

Using the manufacturing apparatus 100 shown in FIG. 1, copper (II) acetylacetonate (Cu (acac) ₂ ) is used as a metal element-containing substance RS, and CNT forest 30 is modified with copper fine particles to obtain a modified CNT forest. rice field. Specifically, the CNT forest 30 was placed in the reaction chamber RC that could be sealed, and Cu (acac) ₂ , which is a metal element-containing substance RS, was placed in the vicinity thereof. Next, the reaction chamber RC was filled with argon gas and the pressure was maintained at 30 Torr. Subsequently, the inside of the reaction chamber RC was heated at a temperature of 400 ° C. for 15 minutes using the heater 20. The CNTs of the CNT forest 30 were modified by the copper fine particles produced by separating Cu (acac) ₂ at 200 ° C. to obtain the modified CNT forest 40. The images shown in FIGS. 3 to 7 are observation views of the manufactured modified CNT forest 40. The fine particles observed in these figures were made of a Cu-based conductive material.

The modified CNT forest produced by the same method as this method was observed using a scanning transmission electron microscope to measure the diameter of the CNT and the particle size of the fine particles. 14 to 17 are diagrams showing the observation results of the modified CNT forest, and FIG. 18 is a histogram showing the measurement results of the particle size of the fine particles. When the diameters of any 13 CNTs selected from the images shown in FIGS. 14 to 17 were measured, the average diameter (average diameter D3) was 36 nm and the standard deviation was 8.6 nm. From the above measurement results, since the number density A of the modified CNT forest is about 10 ¹³ lines / m ² , the adjacent gap D1 of the modified CNT forest is 280 nm (= (10 ¹³ m ^-2 ) ^{-1 /} 2-36 nm). Met. Further, the particle size was measured for any 62 fine particles selected from the images shown in FIGS. 14 to 17, and the average value of the particle size (average particle size D2) was 29.2 nm, and the standard deviation thereof. Was 10.7 nm. Therefore, the ratio R defined by the above equation (1) was 9.7.

The obtained modified CNT forest was spun as shown in FIG. 9 to obtain CNT plyed yarn. The diameter of the obtained CNT plyed yarn was 30 to 35 μm.

Using the apparatus shown in FIG. 13, copper plating was performed on a sample prepared by cutting a part of the obtained CNT plying yarn. The specific conditions are as follows.
-Plating bath: Copper sulfate aqueous solution ("Microfab Cu300" sold by Tanaka Kikinzoku Co., Ltd.)
-Current density: 4 mA / cm ² or 5 mA / cm ²
・ Plating time: 1 hour

A conductive member formed by depositing copper plating on CNT plying was heated at 700 ° C. for 1 hour in a hydrogen stream (100 sccm). In this way, a conductive member to be evaluated was obtained. FIG. 19 is an observation view of the appearance of the conductive member thus obtained, and FIG. 20 is an enlarged observation view of the appearance of the conductive member.

FIG. 21 is an observation view showing a cross section of a conductive member manufactured by including plating with a current density of 5 mA / cm ² . FIG. 22 shows a cross section of a comparative conductive member made by spinning a CNT forest unmodified with copper fine particles and plating the CNT yarn with a current density of 5 mA / cm ² . It is a figure. FIG. 23 is an observation view showing a cross section of a conductive member manufactured by including plating with a current density of 4 mA / cm ² . FIG. 19 shows a cross section of a comparative conductive member made by spinning a CNT forest unmodified with copper fine particles and plating the CNT yarn with a current density of 4 mA / cm ² . It is a figure.

As is clear from the contrast between FIGS. 21 and 22 and the contrast between FIGS. 23 and 24, by using the modified CNT forest, a conductive member having a relatively high copper abundance density on the central side can be obtained. rice field.

By adjusting the plating conditions, a plurality of conductive members having different copper volume ratios (unit: vol%) were produced. Conductivity (unit: S / cm) and specific conductivity (unit: S ・ m ²・ kg ^-1 ) and current capacity (unit: A / cm ² ) and specific current capacity (unit: A) of these conductive members・ Cm · kg ^-1 ) was measured. The results are shown in FIGS. 25 to 28. It should be noted that FIGS. 23 to 28 show the measurement results of CNT yarns obtained by spinning CNT forests not modified with copper fine particles (Cu fraction is 0 vol%) and the results of general pure copper wiring (Cu fraction). 100 vol%) is also shown for comparison.

As shown in FIGS. 23 to 28, it was confirmed that the conductive member has better electrical characteristics than the CNT yarn formed only of CNTs. Specifically, when the volume ratio of copper in the conductive member is 30 vol% or more, the conductivity and the specific conductivity which are substantially not significantly different from those of copper can be obtained, and when the volume ratio of copper is 35 vol% or more, the conductivity is obtained. A current capacity and a specific current capacity that are substantially the same as those of copper were obtained.

(Example 2)
(1) Spinnable CNT Forest Synthesis A vertically oriented CNT was grown on a substrate by a two-step floating catalyst CVD method. Details of the method for synthesizing spunable CNT forests have been described in previous reports. In the first step, a solution containing ferrocene, which is a catalyst precursor of CNT, contained in ethanol is atomized by ultrasonic waves and conveyed onto a Si substrate in a CVD chamber by Ar of a carrier gas. Ferrocene was thermally decomposed on a Si substrate at 700 ° C. to form Fe nanoparticles in situ. In the second step, acetylene was supplied as the carbon source gas, and chlorine gas was supplied for the purpose of lengthening the CNT. A CNT forest having a diameter of 10 nm and a forest length of about 300 μm was synthesized with a CNT growth temperature of 700 ° C. and a growth pressure of 18 Torr. The CNT forest thus obtained could be spun.

(2) Supporting Cu nanoparticles on the CNT forest Copper nanoparticles (hereinafter, also referred to as “Cu-NPs”) were supported on the CNT forest. Cu (acac) ₂ , which is a precursor of Cu-NPs, and a spinnable CNT forest were placed in a CVD chamber and held at 400 ° C. for 15 minutes in a 100% Ar atmosphere of 30 Torr. In this process, Cu (acac) ₂ evaporates and diffuses and thermally decomposes on the CNT surface. Then, it was thermally decomposed on the surface of the CNT, and Cu-NPs were nucleated. Since the vapor of Cu (acac) ₂ diffuses uniformly to the inside of the CNT forest, Cu-NPs are also uniformly deposited in the CNT inside the CNT forest. After supporting Cu-NPs, the cells were vacuum-exhausted and reduced at 350 ° C. for 1 hour in an atmosphere of 100 Torr argon: hydrogen = 4: 1. In addition, the amount of Cu-NPs supported on the CNT forest was controlled by changing the amount of Cu (acac) ₂ . Hereinafter, the spunable CNT forest thus obtained is also referred to as a “Cu-NPs-supported CNT forest”.

(3) Preparation of Cu-NPs-Supported CNT Twisted Threads As in Example 1, when one end of the Cu-NPs-supported CNT forest is pulled out, a CNT bundle (in the present specification, a partial structure of the CNT forest, which is several pieces) is pulled out. (Meaning that the CNTs have adjacent portions and are bundled) were continuously withdrawn to form a unidirectionally oriented CNT conjugate (CNT web). CNT plying was produced by pulling out the CNT web with a slider while twisting it. The rotation speed of the spindle was 14000 rpm, and the withdrawal speed was 50 mm / s. Hereinafter, the CNT twisted yarn thus obtained is also referred to as "Cu-NPs-supported CNT twisted yarn". For comparison, CNT plying was also produced from a CNT forest that did not support Cu-NPs. Hereinafter, this CNT plying yarn is referred to as "unsupported CNT plying yarn".

(4) Copper Plating Treatment In order to deposit copper on the CNT twisted yarn, a Cu-NPs-supported CNT twisted yarn and an unsupported CNT twisted yarn were electroplated using a copper sulfate solution. A direct current was supplied by using a copper plate as an anode and CNT plying as a cathode. The current density was 0.2 A / dm 2 and the current density was set to 0.2 A / dm ² for 2 hours. Further, in order to reduce the copper oxide that may exist and to smooth the circulation of CNT and copper, heat treatment was performed at 500 Torr and 700 ° C. for 1 hour while supplying 400 sccm of argon and 100 sccm of hydrogen. In this way, a filamentous conductive member (hereinafter, also referred to as "CNT / Cu-wire") including a CNT continuum having a yarn shape (CNT twisted yarn) and a plating-based substance deposited on at least a part of the CNTs constituting the CNT twisted yarn. .) Was obtained. As used herein, the term "plating-based substance" means a general term for a plating substance (a substance formed by plating) and a substance based on the plating substance (corresponding to a reduced body of copper plating in this example).

(5) Characteristic evaluation A field emission scanning electron microscope (“SU-8030” manufactured by Hitachi, Ltd.) was used for observing CNTs. In order to observe the cross-section secondary electron image of CNT / Cu-ware, the cross-section of CNT / Cu-ware was processed into good quality using a cross-section polisher (“IB-09020 CP” manufactured by JEOL). A transmission electron microscope (“JEM-2100F” manufactured by JEOL) was used for observing the cross section of CNT / Cu-ware at a high magnification. A CNT / Cu-wire thin film was prepared using FIB (“JIB-4700F” manufactured by JEOL) for observing the transmitted electron image. For the conductivity, the four-terminal method was used under atmospheric pressure. The current capacity was measured using the two-terminal method under high vacuum. If the measurement length of the two-terminal method is short, heat escapes to the electrodes, so the measurement length was set to 1 cm for the purpose of measuring the current capacity of the true sample. Further, the current density when the yarn is broken is defined as the current capacity. The tensile characteristics were a tensile tester (“EZ-L” manufactured by Shimadzu Corporation), the number of measurements was 5, the measurement length was 1 cm, and the tensile speed was 0.05 mm / min. The tensile strain was measured with a non-contact elongation meter (“TRViewX” manufactured by Shimadzu Corporation).

The measurement results of CNT / Cu-wire obtained by the above manufacturing method are shown below.
(1) Dry-spinning (dry spinning) CNT plying from a Cu-NPs-supported CNT forest According to the Cu-NPs-supporting method according to the present embodiment, the amount of Cu-NPs supported can be determined by parameters such as the amount of precursor and temperature. The particle size can be controlled. Cu (acac) ₂ is a sublimable organic compound that sublimates and thermally decomposes at a relatively low temperature. Therefore, it can be said that it is suitable as a precursor that diffuses into the inside of the CNT forest with steam and supports Cu-NPs on the CNT surface in the entire CNT forest.

However, it is necessary to carefully control the conditions under which Cu-NPs are uniformly supported even inside the CNT forest. The thermal decomposition rate of Cu (acac) ₂ changes greatly depending on the pressure and temperature in the chamber. When the temperature is high, the thermal decomposition rate is high, so that Cu-NPs are supported from the side surface of the CNT forest, resulting in the inability to support the inside of the CNT forest. In this example, the supporting conditions of Cu-NPs were carefully examined to obtain a spunable CNT forest that was uniformly supported up to the inside of the CNT forest.

The secondary electron images of the CNT forest carrying Cu-NPs when the amount of Cu (acac) ₂ is changed to 10 mg, 30 mg, and 100 mg are shown in FIGS. 30 (A) to 30 (C). As shown in FIG. 30 (A), when the amount of Cu (acac) ₂ is as small as 10 mg, the amount of Cu-NPs formed on the CNT surface is small, and the amount of Cu-NPs supported is small, and the CNTs not supported by Cu-NPs. Also existed. However, the spinnability was high as in the CNT forest which did not support Cu-NPs.

As shown in FIG. 30 (C), when the amount of Cu (acac) ₂ was as large as 100 mg, the amount of Cu-NPs supported on the CNT surface was very large. In this case, the CNTs were bonded to each other with Cu-NPs, and the entire CNT forest became one combined body. When the end of the CNT forest was pulled out, the CNT bundle adjacent to the pulled out CNT was inseparable from the CNT forest because it was tightly bound to the CNT forest. Therefore, continuous dry spinning did not occur, and when the amount of Cu (acac) ₂ was 100 mg, it was impossible to produce CNT plyed yarn.

As shown in FIG. 30 (B), by setting the amount of Cu (acac) ₂ to 30 mg, a CNT forest in which Cu-NPs were evenly supported on the CNT surface and the spinnability was high was obtained. In this example, since it is necessary to produce CNT plying by spinning, CNT plying was produced using a CNT forest produced with an amount of Cu (acac) ₂ used at 30 mg.

In this example, Cu (acac) ₂ was used as a precursor because the purpose was to combine with copper, but other acetylacetonate complexes (Pt (acac) ₂ , Ni (acac) ₂ , Zn ( By using acac) ₂ etc.), nanoparticles of various metals can be similarly supported in the CNT forest. Therefore, the method according to this embodiment can be utilized not only as a wiring material but also as an electrode material for a battery or a capacitor.

In this embodiment, dry spinning was realized in which Cu-NPs were supported on the entire CNT forest and Cu-NPs were uniformly supported on the extracted CNT web. In this embodiment, since Cu-NPs are supported at the stage of the spinnable CNT forest where the distance between the CNT bundles is wider than that in the CNT twisted yarn, the case where Cu-NPs are supported after the CNT twisted yarn is produced is compared with the case where the Cu-NPs are supported. Cu-NPs can be uniformly supported in the CNT plyed yarn. In the method according to this embodiment, since nanoparticles are supported on the CNT forest in advance, the range of applications is wide, such as Cu-NPs-supported CNT forest, Cu-NPs-supported CNT sheet, and Cu-NPs-supported CNT twisted yarn. The method used in this embodiment has good handleability and is convenient for the user, which is also an advantage.

(2) Structural analysis of CNT / Cu-wire Copper gloss was observed on the surface of the CNT / Cu-wire obtained in this example. FIG. 31 (A) shows a composite yarn (hereinafter, “Mixed CNT / Cu—” in which copper is precipitated on a CNT twisted yarn (Cu-NPs-supported CNT twisted yarn) carrying Cu-NPs in advance using a CNT having a diameter of about 10 nm. It may be described as "wire"). It is a figure which shows the cross section secondary electron image. FIG. 31B is common in that a CNT having a diameter of about 10 nm is used, but a composite yarn in which copper is precipitated on a CNT twisted yarn (non-supported CNT) that does not previously support Cu-NPs (hereinafter, “Unmixed CNT /”). It may be described as "Cu-wire"), and is a diagram showing a cross-sectional secondary electron image. In this specification, "CNT / Cu composite yarn" may be used as a general term for Mixed CNT / Cu-wire and Unmixed CNT / Cu-wire.

As shown in FIG. 31 (A), in the Mixed CNT / Cu-wire, copper was uniformly deposited from the outer peripheral portion to the inner portion of the CNT twisted yarn. In addition, it can be seen from the high magnification image that copper is densely deposited. On the other hand, the Unmixed CNT / Cu-wire has a core-clad structure in which a large amount of copper is deposited on the outer peripheral portion of the CNT plying yarn (the CNT plying yarn is the core and the copper is the clad), as shown in FIG. 31 (B). Was forming). In addition, copper deposited in an island shape was also present inside the CNT plyed yarn. By comparison with FIGS. 31 (A) and 31 (B), it was confirmed that copper can be uniformly deposited even inside the CNT plying by carrying Cu-NPs on the CNT plying in advance and then performing a plating treatment.

Copper ions in the plating solution tend to precipitate as metallic copper on the surface of Cu-NPs, which is stable in surface energy. In this embodiment, Cu-NPs are formed on the entire CNT twisted yarn, and copper ions diffused inside the CNT twisted yarn during plating are deposited as metallic copper on the Cu-NPs surface. Further, since the distance between the CNT bundles of the CNT twisted yarn is about 200 nm, it is considered that the copper ions are sufficiently diffused throughout the CNT twisted yarn due to the impregnation of the plating solution before energization. Furthermore, since the current density during plating is low, the rate-determining process is not ion diffusion but copper precipitation on the CNT surface, so even if plating starts, the ions move further inside and precipitation continues. In this example, it is considered that a homogeneous CNT / Cu-ware could be produced.

A transmitted electron image of a mixed CNT / Cu-wire orthogonal cross section (a cross section at a plane orthogonal to the extending direction of the CNT) is shown in FIG. 32 (A), and a high magnification image thereof is shown in FIG. 32 (B). As shown in these figures, the particle size of the precipitated copper is several hundred nm. Further, it can be seen that copper is deposited between the CNT bundles and is in close contact with the CNT surface. Almost no voids were found between the copper and the CNTs, but nanovoids of several tens of nm were present between the CNT bundles. Further, from the high magnification image (FIG. 32 (B)), it was observed that the CNT covered with the copper matrix had a slightly crushed shape. From this observation, it was confirmed that even if copper started electrolytic precipitation starting from Cu-NPs supported on the CNT surface, copper was deposited so as to surround the CNT at the end of plating.

A transmitted electron image of a parallel cross section of the Mixed CNT / Cu-wire (a cross section in a plane including the extending direction of the CNT) is shown in FIG. 33 (A), and a high magnification image thereof is shown in FIG. 33 (B). As shown in these figures, the CNTs and copper were in continuous contact with each other in the longitudinal direction.
(3) Electrical conduction characteristics of CNT / Cu-wire

FIG. 34 (A) shows the room temperature conductivity of Mixed CNT / Cu-wire and Unmixed CNT / Cu-wire. Data for CNT plying and copper wire (purity 99.99%) are also shown for comparison. The copper volume content of CNT / Cu-ware, which is the horizontal axis of FIG. 34 (A), is deposited in CNT / Cu-ware from the increment of the weight of the CNT twisted yarn before precipitating CNT / Cu-ware and copper. It was calculated by calculating the volume of copper and dividing by the volume of CNT / Cu-wire. FIG. 34 (B) is a graph in which the vertical axis of FIG. 34 (A) is a linear scale.

As shown in FIG. 34 (A), the conductivity of the Mixed CNT / Cu-wire is 2.41 × 105 S / cm, and the conductivity of the Unmixed CNT / Cu-wire is 4.26 × ^{10 4 S} / cm. Met. The conductivity of CNT plying is 2.35 × 10 ² S / cm, which is three orders of magnitude smaller than the conductivity of copper wire (4.5 × 10 ⁵ S / cm). The conductivity of CNT / Cu-wire increased as the volume ratio of copper increased. In the linear scale plot shown in FIG. 34 (B), the Mixed CNT / Cu-wire has a substantially linear relationship with the copper wire, and free electrons moving in the copper matrix dominate as carriers. The conductivity of Unmixed CNT / Cu-wire is lower than the linear relationship. From the cross-sectional secondary electron image of FIG. 31 (B), copper deposited in an island shape can be seen inside the CNT / Cu-wire, so that copper that does not contribute to conductivity is present. As a result, it is considered that the conductivity decreased with respect to the copper content.

FIG. 35 shows the temperature dependence of the electrical resistivity in which each sample is normalized by the value at 300K. As shown in FIG. 35, the electrical resistivity (broken line) of the copper wire increased in proportion to the temperature due to phonon scattering, and the temperature coefficient of resistance (TCR) was 3.3 × 10 ^-3 K ^-1 . .. The electrical resistivity of Mixed CNT / Cu-ware (solid line) and the electrical resistivity of Unmixed CNT / Cu-ware (dotted line) increase with increasing temperature, but the TCR is 1.2 × 10 ^-3 K ^-1 respectively. , 2.0 × 10 ^-3 K ^-1 , which is smaller than copper wire. From this, it is considered that the phonon scattering of electrons is suppressed by CNT. Further, since the mixed CNT / Cu-ware having many contact surfaces between the CNT and the copper matrix has a smaller TCR than the Unmixed CNT / Cu-ware, the phonon scattering of free electrons is reduced near the interface between the CNT and the copper. It is expected to be. As shown in FIG. 35, the temperature coefficient of resistance (TCR) in the range of 300K to ^450K is preferably 1.8 × 10 -3K ^-1 or less when the longitudinal conductivity is measured. , 1.5 × 10 ^-3 K ^-1 or less is more preferable, and 1.2 × 10 ^-3 K ^-1 or less is particularly preferable.

FIG. 36 shows the temperature dependence of the specific conductivity between the mixed CNT / Cu-wire and the copper wire. The specific conductivity (solid line) of the Mixed CNT / Cu-wire is smaller than the specific conductivity (broken line) of the copper wire because it is a CNT that does not contribute to electrical conduction at room temperature (300K). However, since the TCR of the Mixed CNT / Cu-wire is smaller than the TCR of the copper, the specific conductivity of the Mixed CNT / Cu-wire reverses the specific conductivity of the copper wire at 370K. That is, it was confirmed that at 400 K or higher, the specific conductivity of the mixed CNT / Cu-wire is stably realized to be higher than the specific conductivity of the copper wire.

On the other hand, as shown in FIG. 35, the electrical resistivity (dashed line) of the CNT twisted yarn decreased linearly with increasing temperature, and its TCR was −0.6 × 10 ^{-3K -1} . .. The temperature dependence of this negative linear electrical resistance is considered to be influenced by Friedel oscillation.

FIG. 37 shows the current capacity of each sample. The current capacity of the Mixed CNT / Cu-wire was 1.3 × 10 ⁵ A / cm ² , and the current capacity of the Unmixed CNT / Cu-wire was 5.32 × 10 ⁴ A / cm ² . The current capacity of Mixed CNT / Cu-wire is about 2.2 times higher than that of copper wire (5.8 x 10 ⁴ A / cm ² ) even though the volume content of copper is 56.7%. Indicated. Increasing the current density supplied to the CNT / Cu-ware increases the electrical resistance due to the generation of Joule heat in the CNT / Cu-ware. As described above, since the conductivity of CNT / Cu-wire is higher than that of copper in the high temperature band of 370 K or higher, Joule heating with respect to the current density is smaller than that of copper wire. As a result, the temperature rise was reduced and the current capacity was increased. As described above, it was confirmed from FIG. 37 that the mixed CNT / Cu-wire preferably has a current capacity of ^{105 A / cm 2 or} more.

FIG. 38 shows a graph showing the relationship between the specific conductivity and the specific current capacity of each sample. The specific conductivity of Mixed CNT / Cu-wire is 4.31 × 10 ⁴ S · cm ² / g, which is about the same as that of copper wire (4.87 × 10 ⁴ S · cm ² / g) and CNT plying (4). .40 x 10 ² S · cm ² / g), which is more than two orders of magnitude higher. The result was that the specific conductivity was mostly dependent on the copper content. This also supports that the carriers in the composite are copper free electrons. On the other hand, the specific current capacity of the Mixed CNT / Cu-wire was 2.32 × 10 ⁴ A · cm / g, which was 3.6 times larger than the 6.5 × 10 ³ A · cm / g of the copper wire. By suppressing the increase in resistance at high temperatures in CNT / Cu, the transport capacity was greatly improved even though the current was flowing through the copper matrix portion as in the case of copper wire.

The CNT twisted yarn (2.85 × ¹⁰⁴ A · cm / g) had the largest value. It is known that CNT twisted yarn has a sublimation temperature much higher than that of copper and has a high infrared emissivity, so that it can transport current to a temperature higher than that of copper, and has a specific conductivity that is two orders of magnitude smaller than that of copper but exhibits a high specific current capacity. There is. From the above, the Mixed CNT / Cu-wire is lightweight, yet has high conductivity, and has a current capacity that surpasses that of copper wire, so that it can be expected to be applied as a small-diameter wiring capable of supplying high power.

(4) Mechanical Characteristics of CNT / Cu-wire Table 1 shows the characteristic tables of CNT twisted yarn (CNT yarn), CNT / Cu composite yarn and copper wire.

FIG. 39 (A) shows stress-strain diagrams of Mixed CNT / Cu-wire and Unmixed CNT / Cu-wire manufactured using a CNT having a diameter of about 10 nm. For comparison, stress-strain lines of CNT plyed yarn and copper wire manufactured using CNTs having a diameter of about 10 nm are also shown. The tensile strength of Mixed CNT / Cu-ware was 699 MPa, and the Young's modulus was 70.4 GPa. The tensile strength of the copper wire was 191 MPa and the Young's modulus was 83.5 GPa, and the tensile strength of the CNT twisted yarn was 666 MPa and the Young's modulus was 32.2 GPa. As for the tensile strength of Mixed CNT / Cu-wire, both the tensile strength and Young's modulus were improved by the uniform compounding with copper as compared with the CNT twisted yarn. The tensile strength of Unmixed CNT / Cu-wire was 182.9 MPa and the Young's modulus was 25.8 GPa, and both the tensile strength and the Young's modulus decreased. FIG. 39 (B) is a graph showing the relationship between Young's modulus and tensile strength of various samples obtained from the stress-strain diagram of FIG. 39 (A). As shown in FIG. 39 (B), the Young's modulus of Mixed CNT / Cu-ware was significantly increased and the tensile strength was equal to or higher than that of the CNT twisted yarn as a reference. On the other hand, in Unmixed CNT / Cu-ware, the tensile strength was remarkably reduced and the Young's modulus was also lowered. That is, by comparing Mixed CNT / Cu-wall and Unmixed CNT / Cu-ware, the mixed CNT / Cu-ware, which is a filamentous conductive member, is a blank carbon corresponding to the material obtained by removing the plating-based material from the filamentous conductive member. It was shown that it is preferable that the tensile strength is 1.0 times or more and the Young's ratio is 1.5 times or more based on the nanotube continuum, that is, the CNT twisted yarn. It is more preferable that the Young's modulus of the Mixed CNT / Cu-ware is 2.0 times or more based on the CNT twisted yarn.

The secondary electron image of the tensile break portion of the Mixed CNT / Cu-wire is shown in FIG. 40 (A), and the secondary electron image of the tensile break portion of the Unmixed CNT / Cu-wire is shown in FIG. 40 (B). As shown in FIG. 40 (A), the CNT was pulled out shortly at the broken portion of the Mixed CNT / Cu-ware. On the other hand, as shown in FIG. 40 (B), in the Unmixed CNT / Cu-wire, the copper on the outer peripheral portion (clad) was broken and slipped, and the CNT twisted yarn was pulled out for a long time. Since the Young's modulus and tensile strength of the Mixed CNT / Cu-ware are significantly improved compared to the copper wire, not only copper is uniformly deposited in the CNT twisted yarn, but also the adhesion to the surface of the CNT bundle is good. , Copper well transmitted the load between the CNT bundles as a matrix. That is, by comparing FIGS. 40 (A) and 40 (B), it was confirmed that Mixed CNT / Cu-wire can be regarded as a fiber-reinforced composite material using copper as a base material.

FIG. 41 (A) is a diagram showing a secondary electron image of a composite yarn in which copper is deposited on a CNT twisted yarn carrying Cu-NPs. FIG. 41 (B) is a diagram showing a secondary electron image of a buckled portion of a composite yarn in which copper is deposited on a CNT twisted yarn that does not support Cu-NPs. As shown in FIG. 41 (A), the Mixed CNT / Cu-ware can be deformed with a small curvature. This composite yarn was flexible because it was a homogeneous medium in which CNT and copper were homogeneously mixed. On the other hand, as shown in FIG. 41 (B), the Unmixed CNT / Cu-ware easily buckles and fractures. This is because in Unmixed CNT / Cu-wire, the CNT twisted yarn exists in the center as it is, but since the CNT twisted yarn portion cannot bear the compressive load due to bending, the outer peripheral portion (clad) made of copper on the surface easily buckles. It is thought that this is to reach.

As described above, in Example 2, a CNT / Cu composite yarn containing CNTs uniformly in a high proportion was produced. Due to the synergistic effect of CNT and copper, it is an innovative new material with high electrical conductivity, low TCR, high current capacity, high tensile properties and high flexibility. Homogeneous CNT / Cu-wire can be expected as a new lightweight wiring material for drone motors and earphones, small coils for small actuators, and wiring for small electronic device systems with high energy density. In addition, the dry CNT spinning technique in which vapor phase nanoparticles are deposited in order to obtain a homogeneous composite material is a new technique that adds a new aspect to the CNT application. Since CNTs carrying nanoparticles can form various structures such as long fibers, sheets, and three-dimensional structures, CNTs with various functionalities can be applied in the future.

10: Glass tube 20: Heater 30: CNT forest 40: Modified CNT forest 50: CNT
60: CNT continuous body 70: Fine particles 100: Manufacturing equipment 100A: Plating equipment 110: Mica sheet 120: CNT twisted yarn 130: Copper sulfate bath 141, 142: Clips 151, 152: Wiring 160: Power supply 161: Cathode terminal 162: Anode terminal 170: Anode 200: Conductive member D: Direction RC: Reaction chamber RS: Metal element-containing substance SB: Substrate

Claims (21)

1. A carbon nanotube forest with carbon nanotubes oriented in a predetermined direction,
   With fine particles supported on the carbon nanotubes
   A modified carbon nanotube forest characterized by being spinpable.
2. The modified carbon nanotube forest according to claim 1, wherein the ratio R defined by the following formula (1) using the adjacent gap D1 of the carbon nanotubes and the average particle size D2 of the fine particles is 3 or more.
   R = D1 / D2 (1)
   Here, the adjacent gap D1 is represented by the following formula (2) using the number density A (unit: book / m ² ) of the modified carbon nanotube forest and the average diameter D3 of the carbon nanotubes, and the average grain. The diameter D2 and the average diameter D3 are the arithmetic average of the diameters of the fine particles in 10 or more places and the arithmetic of the diameters of the carbon nanotubes in 10 places or more, respectively, measured by observing the modified carbon nanotube forest with an electronic microscope. It is an average.
   D1 = A- ^{1 / 2} -D3 (2)
3. The modified carbon nanotube forest according to claim 1 or 2, wherein the fine particles have conductivity.
4. The modified carbon nanotube forest according to any one of claims 1 to 3, wherein the fine particles contain an oxide.
5. A carbon nanotube continuum comprising the spun body of the modified carbon nanotube forest according to any one of claims 1 to 4.
6. The carbon nanotube continuum according to claim 5, wherein the carbon nanotube continuum has a web shape.
7. The carbon nanotube continuum according to claim 5, wherein the carbon nanotube continuum has a thread shape.
8. The carbon nanotube continuum according to claim 7, which is twisted.
9. The carbon nanotube continuum having the web shape according to claim 6 is provided.
   A gas permeable sheet characterized in that at least a part of carbon nanotubes constituting the carbon nanotube continuum is adjacent to each other with a gap in a direction intersecting the orientation direction thereof.
10. The gas permeable sheet according to claim 9, wherein the carbon nanotubes carry fine particles containing one or more elements selected from the group consisting of Pt and Co.
11. The catalyst electrode of the fuel cell provided with the gas permeable sheet according to claim 9 or 10.
12. A conductive member comprising the modified carbon nanotube forest according to any one of claims 1 to 3 and a plating-based substance deposited on the carbon nanotubes located inside the modified carbon nanotube forest.
13. An interlayer heat conductive material comprising the conductive member according to claim 12.
14. A conductive member comprising the carbon nanotube continuum according to any one of claims 5 to 8 and a plating substance deposited on the carbon nanotubes located inside the carbon nanotube continuum. ..
15. The conductive member according to claim 14, wherein the carbon nanotubes of the carbon nanotube continuum carry fine particles having conductivity.
16. The method for producing a modified carbon nanotube forest according to any one of claims 1 to 4.
    The metal element-containing substance is put into a gas phase state and supplied to the carbon nanotube forest.
    The metal element-containing substance is decomposed to generate a metal-based substance,
    A method for producing a modified carbon nanotube forest, which comprises supporting the fine particles formed from the metal-based substance on the carbon nanotube forest.
17. A filamentous conductive member comprising the carbon nanotube continuum having a thread shape according to claim 6 or 7, and a plating-based substance deposited on at least a part of the carbon nanotubes constituting the carbon nanotube continuum.
18. The filamentous conductive member according to claim 17, which has a current capacity of ¹⁰⁵ A / cm ² or more.
19. The filamentous conductive member according to claim 17 or 18, wherein the temperature coefficient of resistance in the range of 300 K to 450 K is 1.8 × 10 ^-3 K ^-1 or less when the conductivity in the longitudinal direction is measured. ..
20. The filamentous conductive member according to any one of claims 17 to 19, wherein the specific conductivity calculated based on the conductivity measured in the longitudinal direction is 400 K or more and higher than the specific conductivity of the copper wire. ..
21. 17. Claim 17 has a tensile strength of 1.0 times or more and a Young's modulus of 1.5 times or more based on a blank carbon nanotube continuum corresponding to a material obtained by removing the plating-based substance from the filamentous conductive member. The filamentous conductive member according to any one of claims 20.

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