FIELD OF THE INVENTION
00001. The present invention discloses a method of preparation of carbon
nanotubes (CNT) fiber or mat or more particularly the method comprises
collection of multi-wall CNT aerogel and densification of CNT aerogel by
subjecting to the condensation fluid, solidification of the aerogel and collection of
solidified aerogel on a spool in form of the fiber or mat for post processing.
BACKGROUND OF THE INVENTION
2. The electrical and mechanical properties of carbon nanotubes (CNTs) have attracted interest of scientific community since its discovery by Iijima in 1991 [1]. In general, CNTs have been applied in two types of systems; first is microscopic systems such as microsensors, microchips and molecular electronics while other is macroscopic systems such as composites, bucky papers as well as continuous fibers. The research has now shifted towards the applications of the CNT by converting it into useful macrostructures. The present invention is related to nanotubes application in macroscopic systems.
3. Because of its high aspect ratio and exceptional physical properties, CNTs are considered as the "ultimate filler" in composites [2]. The macroscopic structures containing only CNT can bring a revolutionary change in the industries if they can attain a significant portion of the extraordinary mechanical and electrical properties of individual CNT. Development in the low-cost manufacturing technology for robust carbon nanotube (CNT) materials will yield great advances in high-tech applications. Having higher mechanical strength and lighter weight compared to conventional material, these material can be used for applications in aerospace industry. In addition to this, CNT based conductors will find its applications in energy transmission, EMI shielding, motor windings and light weight cabling [3-4].

4. The conversion of CNTs into a macroscopic structures require sufficiently long, highly aligned and packed in arrangement of CNT that is nearly free of defects. The process of growth of macroscopic CNT material is very sensitive to a variety of factors, such as temperature, catalyst, carbon source, pressure, reaction time, carrying gas and method of collection and processing. A slight deviation in any of these factors during the process of growth could result in variations in CNT products [5-6]. Nanotubes from most suppliers, even those from the same batch, are diverse by length, diameter, wall numbers, and chirality. The diversity causes difficulties in the conversion of CNT into macroscopic structure. It is therefore preferable to synthesize CNT macrostructures directly for carbon source instead of growing CNT and converting it to CNT macrostructures.
5. Various methods for processing CNTs into macrostructures have been reviewed by Natnael Behabtu et al [7]. These techniques may be divided into ‘liquid’ methods, where CNTs are dispersed into a liquid and solution spun into fibers; ‘solid’ methods, where CNTs are directly spun into ropes or yarns and ‘gaseous’ methods, where gaseous catalyst and precursors are used to synthesize CNT aerosol which is then condensed in form of thread or mat. Currently, these processes yield fiber or mat whose properties are not sufficiently close to optimal; however, the last few years have seen rapid progress.
6. Many inventors have invented methods to prepare CNT macrostructure and its processing to improve mechanical properties. Some of the most relevant disclosures related to present invention are mentioned here.
7. Invention US005424054A by Bethune et al. relates to hollow carbon fibers (carbon nanotubes) having a cylindrical wall comprising a single layer of carbon atoms and a process for the production of these fibers. The process involves contacting carbon vapor with cobalt. The carbon vapor is produced by electric-arc heating. The cobalt is also vaporized by electric-arc heating and the process is carried out in an inert atmosphere.

8. Invention US007045108B2 by Jiang et al. discloses a method for fabricating a nanotube structure, and more particularly to a method for fabricating a carbon nanotube yarn. The method of fabricating a long carbon nanotube yarn includes the following steps: providing a flat and smooth substrate; depositing a catalyst on the substrate; positioning the substrate with the catalyst in a furnace; heating the furnace to a predetermined temperature; supplying a mixture of carbon containing gas and protecting gas into the furnace; controlling a difference between the local temperature of the catalyst and the furnace temperature to be at least 50° C; controlling the partial pressure of the carbon containing gas to be less than 0.2; growing a number of carbon nanotubes on the substrate such that a carbon nanotube array is formed on the substrate; and drawing out a bundle of carbon nanotubes from the carbon nanotube array such that a carbon nanotube yarn is formed.
9. Lashmore et al. in invention US007611579B2 discloses the systems and methods for synthesis of extended length nanostructures. The system for synthesizing nanostructures using chemical vapor deposition (CVD) includes a housing, a porous substrate within the housing, and on a downstream surface of the substrate, a plurality of catalyst particles from which nanostructures can be synthesized upon interaction with a reaction gas moving through the porous substrate. Electrodes may be provided to generate an electric field to support the nanostructures during growth. A method for synthesizing extended length nanostructures is also disclosed.
000010. In invention US 2007 0140947A1 by Schneider et al. disclosed method
for continuous production of carbon nanotubes mat. The invention relates to a
nanoparticle growing mat, a method of manufacturing the mat, and a method for
the continuous production of organized nanotubes using the mat. The mat
comprising a substrate including carbon, on which is deposited in a
predetermined pattern of nano-sized catalytic particles whose pattern produces
nanotubes in a highly ordered form. The mat is activated in the presence of a
carrier gas, by passing current through the mat which raises the temperature to

the level where, nanotubes are formed; gathered; withdrawn as nanotube bundles and collected.
11. Charlier et al. in invention US 2007 0183959A1 disclosed the process for the production of carbon-based nanotubes, nanofibres and nanostructures. Continuous process for the production of carbon-based nanotubes, nanofibres and nanostructures, comprising the following steps: generating a plasma with electrical energy, introducing a carbon precursor and/or one or more catalyzers and/or carrier plasma gas in a reaction zone of an airtight high temperature resistant vessel optionally having a thermal insulation lining, vaporizing the carbon precursor in the reaction Zone at a very high temperature, preferably above 4000°C, guiding the carrier plasma gas, the carbon precursor vaporized and the catalyzer through a nozzle, whose diameter is narrowing in the direction of the plasma gas flow, guiding the carrier plasma gas, the carbon precursor vaporized and the catalyzes into a quenching zone for nucleation, growing and quenching operating with flow conditions generated by aerodynamic and electromagnetic forces.
12. Recently, Inoue et al. in his patent US20180044819Al has disclosed a method for manufacturing carbon nanotube fiber, apparatus for manufacturing carbon nanotube fiber, and carbon nanotube fiber. The method includes preparing a core material—extending in a predetermined direction; preparing a carbon nanotube array comprising a plurality of carbon nanotubes aligned on a substrate and oriented vertically to the substrate; preparing a carbon nanotube untwisted yam comprising the plurality of continuously connected carbon nanotubes by drawing the carbon nanotube untwisted yarn from the carbon nanotube array; and winding the carbon nanotube untwisted yam around the core material.
13. Morihara et al. in invention US20180073166A1 has described a method for manufacturing a carbon nanotube collected product. The method comprises of preparing a roller comprising a shaft having a cylindrical shape and a resin film located over an entire circumference of the shaft preparing a plurality

of carbon nanotube yams each having a plurality of carbon nanotubes; arranging the plurality of carbon nanotube yams in parallel and along a direction an axis of the shaft extends, and drawing the plurality of carbon nanotube yams in a circumferential direction of the shaft such that they are located on the resin film.
14. Even though the methods reported above relate to processing of carbon nanotubes to form fibers and mats, these cannot be used when carbon nanotubes are grown in gaseous state from gaseous catalyst and precursor. Invention US007045108B2, US20180044819A and US20180073166Al reported above disclose the method for growing and processing CNT by dry-spinning technique wherein aligned CNTs are grown on a catalyst coated substrate such that it comes out as a connected fiber when pulled out from one end. Methods reported in invention US005424054A discloses only method to grow CNT through electric discharge method. The inventors in patent US007611579B2 have disclosed the system and method to for synthesis of extended length CNT using porous substrate, however it does not disclose the method to process CNT and convert it into fiber or mat. Further in invention US20070140947A1, inventors have disclosed the method for continuous growth of CNT using a mat coated with precursor and catalyst, however processing of CNT into fiber or mat is not reported. In the present disclosure, a method for collection of carbon nanotube sock/aerogel in gaseous state and its processing to form fiber and mat has been disclosed.
15. But the technology associated in the conventional method often does not provide the CNT mat with expected efficacy.
000016. The present invention provides the long felt need.
OBJECTS OF THE INVENTION
000017. It is therefore the primary object of the present invention is to provide
a method of preparation of CNT thread and mat from CNT aerogel.

000018. Another object of the present invention is to provide a method of
preparation CNT thread, where the CNT aerogel is condensed, densified and
collected under controlled temperature and atmosphere in the form of a fiber or
non-woven mat.
19. Yet another object of the present invention is to provide a method of preparation CNT thread, where various factors associated with the human safety are included.
20. Further object of the present invention is to provide a method of preparation CNT thread, which is simple, rapid yet effective.
SUMMARY OF THE INVENTION
21. One or more drawbacks of conventional methods for preparation of CNT threads are overcome, and additional advantages are provided through the composition as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in details herein and are considered to be part of the claimed disclosure.
22. A method for preparation of carbon nanotubes (CNT) thread and/or mat from CNT aerogel comprises the steps of :
i) collection of intertwined smoke of highly aligned multiwall CNT; ii) generation of CNT aerogel by using liquid or gaseous precursor including
but not limited to methane, ethane, acetylene, methanol, ethanol, propanol, acetone, diethylether, tetrahydrofuran, ethyl acetate, chloroform. and catalyst including but not limited to ferrocene, ferric chloride and thiophene. iii) feeding the CNT aerogel into collection box at a suitable pressure; iv) condensing of the CNT aerogel by using condensing fluid by exposing to the condensing fluid;

v) alteration of properties of CNT thread by dispersing the metal nanoparticles in the condensing fluid; vi) collection of CNT thread and/or mat with the help of conveyor belt and metal roller; vii) drying of trapped and condensed CNT thread and subjected to anneal to process the crystalline CNT mat or thread.
23. Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, alongwith the accompanying drawing figures.
24. It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
25. The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
26. Figure 1 illustrates the flow chart showing different steps involved in disclosed method to prepare CNT thread/mat from CNT aerogel.
27. Figure 2 illustrates the schematic diagram of the collection box used in disclosed method to prepare CNT thread/mat from CNT aerogel.
28. Figure 3 illustrates the schematic diagram of the apparatus used for conversion of CNT aerogel into a thread by guiding it through bath of condensing fluid.

29. Figure 4 illustrates the schematic diagram of the apparatus used for conversion of CNT aerogel into a mat spraying condensing fluid and collecting it on conveyor belt.
30. Figure 5 illustrates the schematic diagram of the manipulation rod used for attach the CNT aerogel to the conveyor belt and roller.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
31. While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents and alternative falling within the scope of the disclosure.
32. It is to be noted that a person skilled in the art would be motivated from the present disclosure to arrive at a method of preparation of carbon nanotubes (CNT) threads and/or mat. However, such modifications should be construed within the scope of the disclosure. Accordingly, the drawings illustrate only those specific details that are pertinent to understand the embodiments of the present disclosure, so as not to obscure the disclosure with details that will be clear to those of ordinary skill in the art having benefit of the description herein.
33. As used in the description herein and throughout the claims that follow, the meaning of “a”, “an”, and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
34. The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a method, system, assembly, thermoelectric power, generator, thermal energy

that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such method, or assembly, or method. In other words, one or more elements in a system or device proceeded by “comprises…..a “does not, without more constraints, preclude the existence of other elements or additional elements in the system, apparatus or device.
35. The present invention relates to a method for preparation of carbon nanotubes (CNT) thread and/or mat from CNT aerogel, which comprises collection of intertwined multiwall CNT aerogel (gaseous phase) and densification of CNT aerogel by subjecting it to the condensation fluid, solidification of the aerogel and collection of solidified aerogel on a spool in form of the fiber or mat for post processing.
36. The collection of intertwined multiwall CNT aerogel incorporates various catalyst and methods in the form of a fiber or non-woven mat for electrical and mechanical application, not restricted to current carrying conduction and mechanical components with light weight and high strength.
000037. The method converts intertwined smoke of highly aligned multiwall
CNT was generated using liquid or gaseous precursors and catalyst using a
gaseous growth method in the form of a fiber or non-woven mat. Being in a
gaseous state, long aligned nanotubes of length varying from 1 µm to 100 µm
interact with each other to form continuously connected smoke of nanotubes.
000038. The generated CNT aerogel uses gaseous precursors including but not
limited to methane, ethane, acetylene, methanol, ethanol, propanol, acetone,
diethylether, tetrahydrofuran, ethyl acetate, chloroform. and catalyst including
but not limited to ferrocene, ferric chloride and thiophene, which is fed into a
collection box coupled to the exhaust of the furnace through an air tight fitting

(105). The material used for making collection box include but not limited to thermosetting plastic like polycarbonate and metal or its alloy like stainless steel, mild steel. The collection box is maintained at pressure below but close to atmospheric pressure. The pressure inside the box in present invention was maintained at 700 to 760 mm Hg. Before starting the process, the box is evacuated by using a vacuum pump and refilled with an inert purging gas using ports (106) provided on the box for purging and evacuating. The gas used for purging includes but not limited to argon and nitrogen.
39. The collection box is provided with a view port (103) to collect the CNT aerogel and it is also attached to the roller or conveyor.
40. The material used for making view port include but not limited to toughened glass, polycarbonate and borosilicate glass. The viewing port is placed at a position and angle on the box so that view of CNT aerogel in the box is not obstructed by the roller, conveyor, spray nozzles, bath, heater or anything kept in the box. The port is placed on the face of the box opposite to the face coupled with the furnace. The angle of view port with the plane of opposite face may vary from -60° to 60° to avoid obstruction of the view.
000041. In accordance to another embodiment of the present invention, a metal
rod with a handle on one end is provided at the collection box and it is modified
to catch the aerogel on the other end. The metal rod is placed on the face opposite
to the entry of CNT aerogel such that the end with the handle (501) is outside the
box and the other end is inside the box, and movement of the rod is not altering
the atmosphere inside the box. The shape of end of the rod is but not limited to
ring, L-shaped, U-shaped to catch the aerogel and also attached to the roller.
000042. The rod has free movement along the rod (504) to allow it to move into
the furnace tube and back for collection of aerogel. The manipulation rod has

free rotation and provision to move to an angle of 20° from the resting position (505) pivoted at the wall of the box (as shown in figure 5).
43. The figure 2 clearly illustrates the collection box used in this method alongwith all the structural features.
44. Figure 3 and 4 clearly illustrate the densification and condensation of the CNT aerogel.
45. The CNT aerogel is condensed in to the form of densified thread or mat with the use of condensing fluid. The condensing fluids includes but not limited to water and volatile organic solvents like methanol, ethanol, propanol, acetone, diethylether, tetrahydrofuran, ethyl acetate, chloroform. The CNT aerogel is exposed to the condensing fluid either by spraying with a combination of spray nozzles (402) to uniformly wet it (as shown in Figure 4) and convert it into mat form or passed through a bath of the condensing fluid guided through the rollers (302, as shown in Figure 3).
000046. To alter the properties of the CNT thread or mat, metal nanoparticles
are dispersed in the matrix of the CNT. This is done by creating the suspension
of metal nanoparticles in the condensing fluid and using the suspension for
condensing the aerogel by bath and spray. Because of high surface area of CNT
metal particles attach to individual CNT and get entrapped in the matrix of CNT
in thread (305) or mat (404).
000047. The motorized metal rollers and conveyor belt are used to collect the
condensed aerogel as thread and mat. The CNT aerogel is first condensed by
subject ting it to the condensing fluid through spray or bath. The aerogel is
condensed on the surface of the conveyor belt.
000048. The heater is used at the other end of roller and conveyor belt to dry
out remaining condensing fluid trapped in the thread or mat and anneal it online
to make CNT more crystalline. The temperature used for drying the CNT varies
from at 25 to 100°C and for annealing at 200 to 1000°C

49. The following example is presented to further illustrate the invention, but it is not to be considered as limited thereto.
50. The connected and intertwined smoke of highly aligned multiwall CNT was generated using liquid or gaseous precursors and catalyst using a gaseous growth method in a CVD with 100mm outer diameter. Using a vacuum sealed flange, the output end of tube furnace was coupled to a stainless steel box of dimension 1200mm x 800mm x 800mm. The box was maintained at 750 mm Hg using a vacuum pump. Before starting the process, the box was purged with argon and evacuated a few times to remove stray oxygen inside the box. Using L-shaped manipulator, the CNT aerogel was connected to the collection roller through a bath of distilled water guided through the rollers as shown in figure 3. The collected thread was then passed through a circular heater maintained at 100°C to dry it. Annealing was not performed in this illustration.

51. Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.
52. Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
000053. The present disclosure provides a method for preparation of CNT
threads.

Equivalents:
000054. With respect to the use of substantially any plural and/or singular
terms herein, those having skill in the art can translate from the plural to the
singular and/or from the singular to the plural as is appropriate to the context
and/or application. The various singular/plural permutations may be expressly
set forth herein for sake of clarity.
000055. It will be understood by those within the art that, in general, terms
used herein, and especially in the appended claims (e.g., bodies of the appended
claims) are generally intended as “open” terms (e.g., the term “including” should
be interpreted as “including but not limited to”, the term “having” should be
interpreted as “having at least”, the term “includes” should be interpreted as
“includes but is not limited to”, etc.). It will be further understood by those within
the art that if a specific number of an introduced claim recitation is intended,
such an intent will be explicitly recited in the claim, and in the absence of such
recitation no such intent is present. For example, as an aid to understanding, the
following appended claims may contain usage of the introductory phrases “at
least one” and “one or more” to introduce claim recitations. However, the use of
such phrases should not be construed to imply that the introduction of a claim
recitation by the indefinite articles “a” or “an” limits any particular claim
containing such introduced claim recitation to inventions containing only one
such recitation, even when the same claim includes the introductory phrases “one
or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a”
and/or “an” should typically be interpreted to mean “at least one” or “one or
more”); the same holds true for the use of definite articles used to introduce claim
recitations. In addition, eve it a specific number of an introduced claim recitation
is explicitly recited, those skilled in the art will recognize that such recitation
should typically be interpreted to mean at least the recited number (e.g., the bare
recitation of “two recitations”, without other modifiers, typically means at least
two recitations, or two or more recitations).

56. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
57. The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
58. While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

WE CLAIM :

1. A method for preparation of carbon nanotubes (CNT) thread and/or mat from
CNT aerogel comprises the steps of :
i) collection of intertwined smoke of highly aligned multiwall CNT; ii) generation of CNT aerogel by using liquid or gaseous precursor including
but not limited to methane, ethane, acetylene, methanol, ethanol, propanol, acetone, diethylether, tetrahydrofuran, ethyl acetate, chloroform and catalyst including but not limited to ferrocene, ferric chloride and thiophene. iii) feeding the CNT aerogel into collection box at a suitable pressure; iv) condensing of the CNT aerogel by using condensing fluid by exposing to the condensing fluid; v) alteration of properties of CNT thread by dispersing the metal nanoparticles in the condensing fluid; vi) collection of CNT thread and/or mat with the help of conveyor belt and metal roller; vii) drying of trapped and condensed CNT thread and subjected to anneal to process the crystalline CNT mat or thread.
2. The method for preparation of carbon nanotubes (CNT) thread and/or mat as claimed in claim 1, wherein the condensing fluid is selected from water and volatile organic solvents such as methanol, ethanol, propanol, acetone, diethylether, tetrahydrofenol, ethyl acetate and chloroform, ethyl acetate and chloroform.
3. The method for preparation of carbon nanotubes (CNT) thread and/or mat as claimed in claim 1, wherein the drying of condensed CNT takes place at the temperature 25 to 100°C.

4. The method for preparation of carbon nanotubes (CNT) thread and/or mat as claimed in claim 1, wherein the temperature maintained at annealing of the condensed CNT is 200 to 1000°C.
5. The method for preparation of carbon nanotubes (CNT) thread and/or mat from CNT aerogel as claimed in claim 1, wherein the CNT aerogel is exposed to the condensing fluid with combination of spray nozzles.
6. The method for preparation of carbon nanotubes (CNT) thread and/or mat from CNT aerogel as claimed in claim 1, wherein the CNT aerogel is exposed to the condensing fluid by passing through the condensing fluid through the roller.
7. A collection box for feeding the CNT aerogel as claimed in claim 1, comprises a view port placed at a position and at an angle, with the place of the opposite face, so that the aerogel is not obstructed of a metal rod with a hand on one end and the other end is coupled with box on the face opposite to the entry of CNT aerogel and a manipulation rod placed along the axis of CNT aerogel cylinder.
8. The collection box for feeding the CNT aerogel as claimed in claim 7, wherein the angle of the view port with the place of opposite face vary from -60° to 60°.
9. The collection box for feeding the CNT aerogel as claimed in claim 7, wherein the shape of the end of rod is ring, L-shaped and U shaped.
10. The collection box for feeding the CNT aerogel as claimed in claim 7, wherein
the manipulation rod has free rotation and can move to an angle of 20° from the
resting position pivoted at the wall of the box.