Aggregated thread structure, production method thereof, and electric wire using the same

Abstract

A method for producing an aggregated thread structure includes (a) a process of dispersing carbon nanotube to a first solvent, which is water or a mixed solvent containing organic solvent and water, with a surfactant, to create a dispersion and (b) a process of injecting the dispersion, in which carbon nanotube is dispersed, to a condensing liquid, which is a second solvent that differs from the first solvent, to thereby aggregate and spin carbon nanotube. The aggregated thread structure containing carbon nanotube has: a bulk density of 0.5 g/cm 3 or more; a weight reduction rate up to 450° C. of 50% or less; a G/D ratio for resonance Raman scattering measurement of 10 or more; and an electric conductivity of 50 S/cm or more.

1 . An aggregated thread structure containing carbon nanotube, wherein:
 the bulk density is 0.5 g/cm 3  or more;   the weight reduction rate, which is obtained by subtracting heated weight from dry weight, and dividing the result by the dry weight, wherein the dry weight is the weight measured after heating under air from room temperature to 100° C. at a temperature increase rate of 10° C./min and letting stand at 100° C. for 10 minutes, and the heated weight is the weight measured after further heating under air to 450° C. at a temperature increase rate of 10° C./min, is 50% or less;   the G/D ratio, in which G is the maximum peak intensity in the range of 1550 to 1650 cm −1  and D is the maximum peak intensity in the range of 1300 to 1400 cm −1  for the spectrum obtained by resonance Raman scattering measurement, is 10 or more; and   the electric conductivity is 50 S/cm or more.   
     
     
         2 . The aggregated thread structure according to  claim 1 , wherein said weight reduction rate is 25% or less, and
 the G/D ratio for resonance Raman scattering measurement is 30 or more.   
     
     
         3 . The aggregated thread structure according to  claim 1 , wherein said carbon nanotube contains a single-walled carbon nanotube, a double-walled carbon nanotube, or a multiwall carbon nanotube. 
     
     
         4 . The aggregated thread structure according to  claim 1 , wherein the electric conductivity is 500 S/cm or more. 
     
     
         5 . The aggregated thread structure according to  claim 1 , wherein:
 said aggregated thread structure has a diameter of 10 μm or more to 1 cm or less;   the length/diameter ratio is 100 or more;   said aggregated thread structure comprises a plurality of grooves in the longitudinal direction, with a depth of 1 to 3 μm and a length of 30 μm or more; and   said aggregated thread structure comprises a plurality of voids of 100 nm or more to 10 μm or less.   
     
     
         6 . The aggregated thread structure according to  claim 1 , wherein the weight composition ratio of carbon nanotube is 75% or more. 
     
     
         7 . An electric wire, which is wherein it uses the aggregated thread structure according to  claim 1  as a conductor. 
     
     
         8 . An aggregated thread structure containing Carbon nanotube, wherein:
 the bulk density is 0.5 g/cm 3  or more;   the G/D ratio, in which G is the maximum peak intensity in the range of 1550 to 1650 cm −1  and D is the maximum peak intensity in the range of 1300 to 1400 cm −1  for the spectrum obtained by resonance Raman scattering measurement, is 10 or more; and   the electric conductivity is 500 S/cm or more.   
     
     
         9 . A method for producing an aggregated thread structure, which comprises:
 (a) a process of dispersing carbon nanotube to a first solvent, which is water or a mixed solvent containing organic solvent and water, with a surfactant, to create a dispersion;   (b) a process of injecting said dispersion of carbon nanotube to a condensing liquid, which is a second solvent differing from the first solvent, to thereby aggregate and spin carbon nanotube; wherein   said first solvent is water or a mixed solvent of one or more organic solvent selected from the group consisting of methanol, ethanol, propanol, formamide, ethylene glycol, and dimethyl sulfoxide, and water;   said condensing liquid is a solution containing one of N-methylpyrrolidone, N,N-dimethyl acetamide, propylene carbonate, formamide, N-methyl formamide, water, methanol, ethanol, or propanol, and said condensing liquid and said first solvent differ in their affinity to said surfactant; and   the pH of said condensing liquid is 3 to 11.   
     
     
         10 . The method for producing an aggregated thread structure according to  claim 9 , wherein said surfactant is a surfactant selected from one or more type(s) selected from the following groups (1) to (3):
 (1) a non-ionic surfactant with an HLB, calculated by the Griffin method, of 8 or more;   (2) an anionic surfactant: alkyl benzene sulfonate, alkyl alcohol sulfate salt, sodium alkyl diphenyl ether disulphonate, sodium polyoxyethylene alkyl ether sulfate, sodium diakyl sulfosuccinate, sodium alkyl aryl sulfosuccinate, n-lauroyl sarcosine sodium salt, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium (meta)acryloyl polyoxyalkylene sulfate, alkyl alcohol phosphate;   (3) a cationic surfactant: tetra alkyl ammonium halide.   
     
     
         11 . The method for producing an aggregated thread structure according to  claim 10 , wherein said surfactant is a combination of one or more surfactants selected from each of said group (1) and said group (2), or each of said group (1) and said group (3). 
     
     
         12 . The method for producing an aggregated thread structure according to  claim 10 , wherein said surfactant comprises a plurality of surfactants with different lengths of main chain. 
     
     
         13 . The method for producing an aggregated thread structure according to  claim 10 , wherein said surfactant comprises sodium dodecyl sulfate. 
     
     
         14 . The method for producing an aggregated thread structure according to  claim 9 , which further comprises:
 a process of extracting said aggregated thread structure from said condensing liquid and immersing in a solvent;   a process of drying said aggregated thread structure; and   a process of stretching said aggregated thread structure;   
       following said process (b). 
     
     
         15 . The method for producing an aggregated thread structure according to  claim 14 , which further comprises a process of twisting said aggregated thread structure. 
     
     
         16 . The method for producing an aggregated thread structure according to  claim 9 , wherein said carbon nanotube is one that has been treated for catalyst removal. 
     
     
         17 . An aggregated thread structure, which is produced by the production method according to  claim 9 . 
     
     
         18 . An aggregated thread structure, which is produced by the production method according to  claim 9 , wherein:
 the bulk density is 0.5 g/cm 3  or more;   the weight reduction rate, which is obtained by subtracting heated weight from dry weight, and dividing the result by the dry weight, wherein the dry weight is the weight measured after heating under air from room temperature to 100° C. at a temperature increase rate of 10° C./min and letting stand at 100° C. for 10 minutes, and the heated weight is the weight measured after further heating under air to 450° C. at a temperature increase rate of 10° C./min, is 50% or less; and   the G/D ratio, in which G is the maximum peak intensity in the range of 1550 to 1650 cm −1  and D is the maximum peak intensity in the range of 1300 to 1400 cm −1  for the spectrum obtained by resonance Raman scattering measurement, is 10 or more.