Process for preparing a yarn comprising carbon nanotubes and yarn prepared thereby

Abstract

The present invention provides a process for preparing a yarn, which comprises introducing a raw material that comprises a carbon source and a catalyst into a reaction chamber having a heating means, converting the carbon source into a plurality of carbon nanotubes in a heating part of the reaction chamber with thermal energy supplied by the heating means, and growing the plurality of carbon nanotubes in the vertical direction to form a yarn by the interactions among the carbon nanotubes.

Claims

1. A process for preparing a yarn, which comprises: introducing a raw material that comprises a carbon source and a catalyst, into a reaction chamber having a heating means; converting the carbon source into a plurality of carbon nanotubes in a heating part of the reaction chamber with thermal energy supplied by the heating means; and growing the plurality of carbon nanotubes in the vertical direction to form a yarn by the interactions among the carbon nanotubes, wherein the following parameter M is controlled so as to be maintained at 150° C..Math.m.Math.mg/sec to 1,800° C..Math.m.Math.mg/sec, wherein the yarn has a polarized Raman ratio of 5 to 10, wherein the polarized Raman ratio is a ratio (IGII/IG⊥) of maximum intensity of G peaks in a longitudinal direction of the yarn and a vertical direction of the yarn in a range of 1,560 cm−1 to 1,600 cm−1 in a Raman spectrum analysis:
M=T.Math.L.Math.L.Math.F in the above equation, T is the operating temperature (° C.) of the heating means, L is the length of the heating part (m), and F is the feed rate of the raw material (mg/sec).

2. The process for preparing a yarn of claim 1, wherein the parameter M is controlled so as to be maintained at 160° C..Math.m.Math.mg/sec to 1,400° C..Math.m.Math.mg/sec.

3. The process for preparing a yarn of claim 1, wherein the mass ratio of the catalyst to the carbon source is 0.01 to 0.2.

4. The process for preparing a yarn of claim 1, wherein the yarn has a breaking strength of 13 cN or more.

5. The process for preparing a yarn of claim 1, wherein the operating temperature of the heating means is 550° C. to 2,500° C., the length of the heating part is 0.01 m to 10 m, and the feed rate of the raw material is 0.05 mg/sec to 10 mg/sec.

6. The process for preparing a yarn of claim 5, wherein the operating temperature of the heating means is 1,050° C. to 1,500° C., the length of the heating part is 0.1 m to 2 m, and the feed rate of the raw material is 0.1 mg/sec to 3 mg/sec.

7. The process for preparing a yarn of claim 1, wherein the reaction chamber comprises: an inlet formed at the top thereof to introduce a raw material; a heating part extending downward from the inlet and provided with a heating means on the inner and/or outer side thereof, in which an operating temperature environment is made such that a carbon source is converted into a plurality of carbon nanotubes; a gathering part extending downward from the heating part, in which the plurality of carbon nanotubes is gathered to form a yarn by the π-π interaction; and an outlet extending downward from the gathering part and discharging the yarn in which the carbon nanotubes are gathered.

8. The process for preparing a yarn of claim 7, which further comprises applying a magnetic field to the inside and/or outside of at least one of the gathering part and the outlet in order for the lower ends of the plurality of carbon nanotubes that are being, and/or have been, converted to be vertically aligned.

9. The process for preparing a yarn of claim 1, wherein the carbon source comprises at least one selected from the group consisting of methanol, ethanol, isopropyl alcohol, butanol, pentanol, cetyl alcohol, ethylene glycol, propylene glycol, glycerol, erythritol, xylitol, sorbitol, bolemitol, ally alcohol, geraniol, propargyl alcohol, inositol, menthol, methane, hexane, ethylene, acetylene, methyl acetylene, and vinyl acetylene.

10. The process for preparing a yarn of claim 1, wherein the catalyst comprises at least one metallocene, and the metallocene is a compound of iron, nickel, cobalt, platinum, ruthenium, molybdenum, Or vanadium.

11. The process for preparing a yarn of claim 10, wherein the metallocene is ferrocene.

12. The process for preparing a yarn of claim 1, wherein the raw material further comprises 0.01 to 5 parts by weight of a catalyst activator per 100 parts by weight of the carbon source.

13. The process for preparing a yarn of claim 1, wherein a carrier gas is introduced into the reaction chamber together with the raw material in the step of introducing the raw material.

14. The process for preparing a yarn of claim 13, wherein the carrier gas comprises hydrogen gas and at least one of nitrogen gas and argon gas, and the hydrogen gas is contained in an amount of greater than 0% by volume up to 90% by volume based on the total volume of the carrier gas.

15. The process for preparing a yarn of claim 13, wherein the carrier gas is introduced at a feed rate of from 1 mg/sec to 200 mg/sec.

16. The process for preparing a yarn of claim 1, wherein the step of converting into carbon nanotubes is a step in which the carbon source is graphitized and/or carbonized on the catalyst for a carbon rearrangement, and the carbon nanotubes grow in the vertical direction on the catalyst.

17. The process for preparing a yarn of claim 1, wherein the step of obtaining a yarn comprises immersing the yarn discharged from the reaction chamber in a solvent and winding the immersed yarn using a cylindrical roller or a plate.

18. A yarn prepared by the process for preparing a yarn according to claim 1.

19. The process for preparing a yarn of claim 1, further comprising: forming at least a portion of the yarn outside of the heating part.

20. The process for preparing a yarn according to claim 1, further comprising: gathering the yarn outside of the heating part by a gathering part using π-π interactions among the carbon nanotubes, wherein the gathering part is positioned below the yarn and wherein the gathering part has a temperature that is lower than a temperature of the heating part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of a reaction chamber for preparing yarns.

(2) FIG. 2 is a graph showing polarized Raman spectra of Example 1.

(3) FIG. 3 is a graph showing polarized Raman spectra of Example 2.

(4) FIG. 4 is an SEM photograph of the surface of a yarn prepared according to Example 1.

(5) FIG. 5 is an SEM photograph of the surface of a yarn prepared according to Example 2.

(6) FIG. 6 is a graph showing polarized Raman spectra of Comparative Example 1.

(7) FIG. 7 is a graph showing polarized Raman spectra of Comparative Example 2.

(8) FIG. 8 is an SEM photograph of the surface of a yarn prepared according to Comparative Example 1.

(9) FIG. 9 is an SEM photograph of the surface of a yarn prepared according to Comparative Example 2.

(10) Hereinafter, the function and effect of the present invention will be described in more detail through specific examples of the present invention. However, these examples are merely illustrative of the invention and are not intended to limit the scope of the invention.

EXAMPLES

Example 1

(11) A raw material containing ferrocene as a catalyst, methane as a carbon source, and thiophene as a catalyst activator was fed through the inlet of the reaction chamber at a feed rate (F) of about 0.5 mg/sec to 1 mg/sec. The raw material was fed at a ratio of thiophene:ferrocene:methane=1:1.46:26.3 on a weight basis. A carrier gas with a volume ratio of argon:hydrogen of 9:1 was fed at a rate of 10 mg/sec to 30 mg/sec with the raw material.

(12) At that time, the operating temperature (T) of the heating means of the reaction chamber was controlled to about 1,200° C. to 1,300° C., the length of the heating part was 1.2 m, and the carrier gas was supplied at a rate of about 16 mg/sec.

(13) The yarn discharged from the outlet at the bottom of the reaction chamber was immersed in a bath containing ethanol, and the solvent was dried well by winding the yarn with a winding means to obtain a yarn having a length of about 1 m.

(14) Here, in the preparation of a yarn according to Example 1, the feed rate (F) and the operating temperature (T) were controlled such that the following parameter M was maintained at about 1,034° C..Math.m.Math.mg/sec from the start to the end of the preparation:
M=T.Math.L.Math.F

Example 2

(15) A yarn having a length of about 1 m was prepared according to the method of Example 1, except that the feed rate (F) and the operating temperature (T) were controlled such that the parameter M was maintained at about 235° C..Math.m.Math.mg/sec from the start to the end of the preparation.

Comparative Example 1

(16) A yarn having a length of about 1 m was prepared according to the method of Example 1, except that the feed rate (F) and the operating temperature (T) were controlled such that the parameter M was maintained at about 1,851° C. m.Math.mg/sec from the start to the end of the preparation.

Comparative Example 2

(17) A yarn having a length of about 1 m was prepared according to the method of Example 1, except that the feed rate (F) and the operating temperature (T) were controlled such that the parameter M was maintained at about 141° C..Math.m.Math.mg/sec from the start to the end of the preparation.

Test Example 1: Evaluation of the Degree of Alignment of a Yarn

(18) In order to evaluate the degree of alignment of carbon nanotubes, the polarized Raman ratio (IGII/IG⊥) of the yarns prepared in the Examples and the Comparative Examples was measured, and the results are shown in Table 1 below.

(19) The graphs of the polarized Raman ratios of Examples 1 and 2 are shown in FIGS. 2 and 3, respectively. The graphs of the polarized Raman ratios of Comparative Examples 1 and 2 are shown in FIGS. 6 and 7.

(20) TABLE-US-00001 TABLE 1 Parameter M Polarized Raman ratio (° C. .Math. m .Math. mg/sec) (IG.sub.II/IG.sub.⊥) Example 1 1034 5.28 Example 2 235 5.05 Comparative 1851 3.34 Example 1 Comparative 141 3.81 Example 2

(21) As can be seen from Table 1 and FIGS. 2 and 3, Examples 1 and 2, in which the parameter M was controlled to fall within the scope of the present invention, showed a good polarization Raman ratio of 5 or more, respectively.

(22) The polarized Raman ratio is conventionally proportional to the degree of alignment of carbon nanotubes that constitute a yarn. Thus, it can be deduced from these values that the yarns prepared according to the preparation process of the present invention have carbon nanotubes well aligned therein as compared with the Comparative Examples.

(23) In this regard, FIG. 4 shows an SEM photograph of a yarn produced according to Example 1, and FIG. 5 shows an SEM photograph of a yarn prepared according to Example 2.

(24) Referring to these drawings, it can be confirmed that the surfaces of the yarns of Examples 1 and 2 are smoothly arranged and that there is no gap on the surface of the yarns. Thus, the carbon nanotubes are gathered at a high density. In addition, an undesirable feature such as a shape in which carbon nanotube fibers are entangled or a part of carbon nanotubes are branched is hardly observed. Thus, it is expected that the yarns of Examples 1 and 2 will have excellent strength.

(25) In contrast, according to Table 1, Comparative Examples 1 and 2, in which the parameter M fell outside the scope of the present invention, show polarization Raman ratios significantly lower than those of the Examples. It can be inferred from these results that the alignment of carbon nanotubes is not at the desired level, unlike the Examples.

(26) In this regard, FIG. 8 shows an SEM photograph of a yarn produced according to Comparative Example 1, and FIG. 9 shows an SEM photograph of a yarn prepared according to Comparative Example 2.

(27) Referring to these drawings, it can be confirmed that the surfaces of the yarns of Comparative Examples 1 and 2 are not smoothly arranged since the carbon nanotubes have a plurality of branches and that the carbon nanotubes are complicatedly entangled and contain a large amount of impurities. Particularly noteworthy is that the carbon nanotubes in Comparative Examples 1 and 2 are not gathered at a high density with some spaces between one another. Thus, it is expected that the yarns will have poor strength.

(28) It is understood from the results of Test Example 1 that when the parameter M satisfies the range of the present invention, it is possible to prepare a yarn in an ideal state in which the carbon nanotubes are well aligned at a high density and have a good polarized Raman ratio.

Test Example 2: Evaluation of Strength

(29) The breaking strength tests were carried out for the yarns prepared in the Examples and the Comparative Examples. The breaking strength tests were carried out using an FAVIMAT+ equipment from Textechno. The load cell range was 210 cN. The gauge length was 2 cm, and the experiment was carried out at a speed of 2 mm/min. The results of the breaking strength measurement are shown in Table 2 below.

(30) TABLE-US-00002 TABLE 2 Parameter M Breaking strength (° C. .Math. m .Math. mg/sec) (cN) Example 1 1034 16.4 Example 2 235 17.2 Comparative 1851 2.6 Example 1 Comparative 141 6.1 Example 2

(31) As shown in Table 2, Examples 1 and 2 show remarkably excellent breaking strength as compared with the Comparative Examples.

(32) It is understood in conjunction with Test Example 1 that when the parameter M satisfies the range of the present invention, it is possible to prepare a yarn in an ideal state in which the carbon nanotubes are well aligned at a high density and have a good polarized Raman ratio and that when the yarn has this configuration, it will have very excellent breaking strength.

(33) Although the present invention has been fully described by way of example, it is to be understood that the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.