U.S. patent application number 17/465645 was filed with the patent office on 2021-12-23 for methods of using n-containing compounds with carbon black to replace pan and form carbon fibers.
This patent application is currently assigned to UNM Rainforest Innovations. The applicant listed for this patent is UNM Rainforest Innovations. Invention is credited to Richard Alan Kemp, Mahmoud Reda Taha.
Application Number | 20210395531 17/465645 |
Document ID | / |
Family ID | 1000005822789 |
Filed Date | 2021-12-23 |
United States Patent
Application |
20210395531 |
Kind Code |
A1 |
Kemp; Richard Alan ; et
al. |
December 23, 2021 |
Methods of Using N-Containing Compounds with Carbon Black to
Replace Pan and Form Carbon Fibers
Abstract
A method and precursor for making carbon fibers and the like
comprising carbon black modified with at least one cyclic compound
promoter. A source of the carbon black may be recycled materials
such as recycled tires or recycled plastics. The carbon black is
modified by attaching at least one cyclic compound promoter to the
outer periphery of the carbon black.
Inventors: |
Kemp; Richard Alan;
(Albuquerque, NM) ; Taha; Mahmoud Reda;
(Albuquerque, NM) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UNM Rainforest Innovations |
Albuquerque |
NM |
US |
|
|
Assignee: |
UNM Rainforest Innovations
Albuquerque
NM
|
Family ID: |
1000005822789 |
Appl. No.: |
17/465645 |
Filed: |
September 2, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16565359 |
Sep 9, 2019 |
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17465645 |
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15537241 |
Jun 16, 2017 |
10442934 |
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PCT/US2015/066769 |
Dec 18, 2015 |
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16565359 |
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62094330 |
Dec 19, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D01F 1/10 20130101; D01F
9/1275 20130101; C09C 1/482 20130101; C09C 1/48 20130101; C08F
120/44 20130101; D01F 9/225 20130101; D01F 9/21 20130101 |
International
Class: |
C09C 1/48 20060101
C09C001/48; C08F 120/44 20060101 C08F120/44; D01F 1/10 20060101
D01F001/10; D01F 9/22 20060101 D01F009/22; D01F 9/21 20060101
D01F009/21; D01F 9/127 20060101 D01F009/127 |
Claims
1-45. (canceled)
46. A method of making carbon fibers comprising the steps of: 1)
providing a precursor , said precursor comprising carbon black with
at least one cyclic compound promoter, said at least one cyclic
compound promoter is a nitrogen (N)-containing compound; 2)
combining said precursor with PAN; performing a stabilization
process on said combined PAN and precursor; 3) preforming a
carbonization process on said combined PAN and precursor; and 4)
performing a graphitization process on said combined PAN and
precursor.
47. The method of claim 46 wherein said precursor contains more
than 10% carbon black.
48. The method of claim 46 wherein said carbon black is from
recycled tires or recycled plastics.
49. The method of claim 46 wherein said carbon black is modified by
attaching said at least one cyclic compound promoter to the
periphery of the carbon black.
50. The method of claim 46 wherein said carbon black is modified by
attaching said at least one cyclic compound promoter to the
periphery of the carbon black.
51. The method of claim 46 wherein said carbon black is modified by
attaching said nitrogen (N)-containing compound to the outer
periphery of the carbon black.
52. The method of claim 46 wherein said N-containing compound is
from the group including organics containing di-cyano groups,
cyanamide, carbodiimides, pyridine, 2,2-bipyridine, ammonia,
hydrazine, 2-aminopyridine, 2-cyanopyridine, and related
compounds.
53. The method of claim 46 wherein said N-containing compound
contains cyano-groups that simulate the cyano group cyclization
process.
54. The method of claim 46 wherein said stabilization process
includes heating said combined PAN and precursor to cause polymer
chains in said combined PAN and precursor to begin crosslinking to
increase fiber density.
55. The method of claim 54 wherein said stabilization process
includes heating said combined PAN and precursor in Oxygen in the
range of 204 C to 399 C.
56. The method of claim 46 wherein said carbonization process
includes heating said combined PAN and precursor to remove
non-carbon molecules in said combined PAN and precursor.
57. The method of claim 56 wherein said carbonization process
includes heating said combined PAN and precursor in Nitrogen in the
range of 482 C to 1,482 C.
58. The method of claim 46 wherein said graphitization process
includes heating said combined PAN and precursor in Nitrogen.
59. The method of claim 46 wherein said graphitization process
includes heating said combined PAN and precursor in Nitrogen in the
range of 1982 C to 3,326 C.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Ser. No.
16/565359 filed Sep. 9, 2019, which is a continuation of U.S. Ser.
No. 15/537241 filed Jun. 16, 2016, now issued as U.S. Pat. No.
10,442,934 on Oct. 15, 2019, which is a U.S. 371 National Phase of
PCT/US2015/066769 filed on Dec. 18, 2015 which claims the benefit
of U.S. Provisional Application No. 62/094,330 filed on Dec. 19,
2014, all of which are herein incorporated by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH &
DEVELOPMENT
[0002] Not applicable.
INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT
DISC
[0003] Not applicable.
BACKGROUND OF THE INVENTION
[0004] In order to produce carbon fibers, an expensive
nitrogen-containing polymer (polyacrylonitrile, or PAN) is
generally used which is heated to ultimately give the pure carbon
fibers.
BRIEF SUMMARY OF THE INVENTION
[0005] In one embodiment, the present invention provides an
inexpensive and efficient method to produce pure carbon fibers. The
resulting carbon fibers may be used in products such as graphene
sheets and high tech composites.
[0006] In another embodiment, inexpensive carbon blacks are
combined with one or more compounds that promote the formation of a
cyclic carbon black compound that may be used to replace or be used
in combination with the expensive PAN and/or pitch.
[0007] In another embodiment, inexpensive carbon blacks are
combined with one or more nitrogen-containing organic compounds to
replace or be used with part of the expensive PAN and/or pitch.
[0008] In other embodiments, the present invention simulates
producing PAN-based carbon fibers by substituting recycled carbon
blacks that have been modified with inexpensive nitrogen
(N)-containing compounds for all or part of the expensive PAN
polymer material.
[0009] In other embodiments, the present invention replaces pitch
and/or PAN precursors with a precursor made from recycled carbon
black that has been modified with at least one N-containing
compound.
[0010] In other embodiments, the present invention chemically
attaches N-containing compounds to the periphery of the carbon
black to create a precursor that is similar to the chemistry
associated with a PAN precursor.
[0011] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0012] In the drawings, which are not necessarily drawn to scale,
like numerals may describe substantially similar components
throughout the several views. Like numerals having different letter
suffixes may represent different instances of substantially similar
components. The drawings illustrate generally, by way of example,
but not by way of limitation, a detailed description of certain
embodiments discussed in the present document.
[0013] FIG. 1A is a full atomic schematic of the structural changes
of PAN-based carbon fiber during the stabilization step of the
manufacturing process.
[0014] FIG. 1B is a simpler schematic (equivalent to the full
atomic schematic) of the structural changes of PAN-based carbon
fiber during the stabilization step of the manufacturing
process.
[0015] FIG. 2A illustrates the structural changes of PAN-based
carbon fiber during the carbonization step of the manufacturing
process.
[0016] FIG. 2B illustrates the structural changes of PAN-based
carbon fiber during the graphitization step of the manufacturing
process.
[0017] FIG. 2C illustrates a putative carbon black structure with
attached cyclic compound promoters that may be used in accordance
with an embodiment of the present invention.
[0018] FIG. 3 illustrates generic and exemplary N-containing
compounds that may be used with an embodiment of the present
invention.
[0019] FIG. 4 illustrates a method of producing carbon fiber in
accordance with an embodiment of the present invention.
[0020] FIG. 5 illustrates mix proportions for producing carbon
black based PAN-like material in accordance with an embodiment of
the present invention.
[0021] FIG. 6 illustrates load-indentation depths of carbon black
based PAN-like material produced in accordance with an embodiment
of the present invention.
[0022] FIG. 7 illustrates the stiffness achieved by carbon black
based PAN-like material produced in accordance with an embodiment
of the present invention.
[0023] FIG. 8 illustrates the hardness (strength) achieved by
carbon black based PAN-like material produced in accordance with an
embodiment of the present invention.
[0024] FIGS. 9A and 9B illustrate the scatter of carbon black based
PAN-like material in hardness versus modulus plot showing the new
material to have very similar mechanical properties to PAN.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Detailed embodiments of the present invention are disclosed
herein; however, it is to be understood that the disclosed
embodiments are merely exemplary of the invention, which may be
embodied in various forms. Therefore, specific structural and
functional details disclosed herein are not to be interpreted as
limiting, but merely as a representative basis for teaching one
skilled in the art to variously employ the present invention in
virtually any appropriately detailed structure. Further, the terms
and phrases used herein are not intended to be limiting, but rather
to provide an understandable description of the invention.
[0026] The production of carbon fibers begins with a precursor that
is typically made from polyacrylonitrile (PAN) which is a
synthetic, semicrystalline organic polymer resin, with the linear
formula (C.sub.3 H.sub.3 N). Another less common precursor are
pitches, which are generally complex blends of polyaromatic
molecules and heterocyclic compounds. Pitches are often obtained
from petroleum refining, coal, asphalt, or the pyrolysis of PVC.
However, the vast majority of carbon fibers are made from PAN
precursors.
[0027] As is known in the art, PAN precursor formation begins with
an acrylonitrile monomer, which is combined in a reactor with
plasticized acrylic comonomers and a catalyst to promote
polymerization to create long-chain polymers that can be formed
into acrylic fibers. FIGS. 1A-1B and FIGS. 2A-2B illustrate the
structural changes PAN undergoes through the manufacturing
processes described above and below.
[0028] As shown in FIGS. 1A and 1B, PAN (left side) is first heated
to convert the compound from a chain-like structure to form cyclic
or ringed structures (right side). To promote the formation of
carbocylces and heterocycles, the compound is subject to one or
more processing steps such as dehydrogenation (FIG. 2A) and
denitrogenation (FIG. 2B). These steps are performed to remove
hydrogen and nitrogen to promote the formation of carbocyles and
heterocycles.
[0029] The PAN precursors generally undergo a process called
spinning where the precursor is extruded through holes to create
filaments which may repeatedly be drawn and stretched to continue
orienting the PAN polymer. Next, the fiber is oxidized to cause the
polymer chains to begin crosslinking to increase fiber density. In
the end, the oxidized (stabilized) PAN fiber contains about 50 to
65 percent carbon molecules, with the balance a mixture of
hydrogen, nitrogen and oxygen. The fibers are then carbonized to
remove non-carbon molecules. The crystallization of the carbon
molecules may be optimized to produce a finished fiber that is more
than 90 percent carbon.
[0030] In a preferred embodiment, the present invention provides a
process for making a PAN-like material for making carbon fibers by
providing a carbon black precursor, a source of which may be used
tires or other recycled products, modified with one or cyclic
compound promoters. In other embodiments, fresh carbon black may be
used as well.
[0031] In other preferred embodiments, the present invention
provides a substitute for the PAN polymer precursor by attaching
one or more cyclic compound promoters (CCPs) 100-102 (not drawn to
scale or in number used) to carbon black as shown in FIG. 2C, to
make a carbon black precursor 120. FIG. 2C shows an exemplary
carbon black structure 110 and other carbon black structures are
within the scope of the present invention.
[0032] CCPs 100-102 may be a single compound or a mixture of
compounds. CCPs 100-102 may also be a monomer, a polymer or a
mixture of monomers and polymers. In a preferred embodiment, CCPs
100-102 are chemically attached to carbon black structure 110. In
other embodiments, CCPs 100-102 are chemically attached to the
periphery and/or outer periphery of carbon black structure 110. In
still further embodiments, CCPs 100-102 may also be attached to one
or more functional groups 130-132.
[0033] In a preferred embodiment, the present invention uses one or
more N-containing compounds, monomers, and/or polymers as the CCPs.
In yet other embodiments, one or more of the compounds shown in
FIG. 3 may be used as the CCPs.
[0034] Representative examples of CCPs include, but are not limited
to, organics containing di-cyano groups, cyanamide, carbodiimides,
pyridine, 2,2-bipyridine, ammonia, hydrazine, 2-aminopyridine,
2-cyanopyridine, and related compounds. Other compounds that may be
used may or may not contain cyano-groups, but would have
functionalities that simulate the cyano group cyclization
process.
[0035] It is possible to generate CCPs in situ by utilizing
synthetic routes that generate nitriles from other precursors, such
as organic amides, organic halides, or related compounds. Other
CCPs may rely on atoms that resemble the N atom in the various
structure in function, yet are not N. It is well-known in the
chemical literature that elements such as P which reside in the
same family as N, often have similar chemistry and are capable of
forming cyclic structures. Compounds as shown in FIG. 3 in which N
is substituted by P would be exemplary.
[0036] Carbon black structure 110 with the attached CCPs form
carbon black precursor 120 which may be processed to remove the
CCPs to promote the formation of carbocyles and/or heterocycles.
The processing may include one or more of of the following steps 1)
stabilization such as shown in FIGS. 1A, 2) carbonization such as
shown in FIGS. 2A, and 3) graphitization such as shown in
[0037] FIG. 2B. One or more of steps 1-3 may be repeated, omitted
and/or performed out of order.
[0038] In one embodiment, carbon black precursor 120 may replace
PAN or pitch in the production of carbon fibers. In yet other
embodiments, carbon black precursor 120 may be used in combination
with PAN or pitch in the production of carbon fibers, sheets and
other materials.
[0039] FIG. 4 illustrates a method of processing carbon fibers in
accordance with several embodiments of the invention. As shown,
carbon black precursor 350 may replace Pan or pitch or be used in
combination with PAN and/or a pitch in step 400 to create a
precursor for processing. The precursor is stabilized in step 410
and then undergoes carbonization in step 420. The final step, 430,
is graphitization and thereafter the carbon fibers are sized and
packaged. As described above, the steps may be repeated and/or
performed out of order and in differing combinations.
[0040] FIG. 5 illustrates mixtures of PAN, pitch and carbon black
precursor 120 used in accordance with several embodiments of the
invention. As shown in FIGS. 6-9, carbon fibers produced from
mixture 4 have similar performance to fibers made from PAN that is
mixture 1.
[0041] The lower cost of using carbon black (available from many
industrial processing and recycling sources) with inexpensive CCPs,
such as N-containing compounds, provides economic advantages not
found in the prior art. In other embodiments, the present invention
achieves approximately most of the strength of PAN-based carbon
fibers using carbon black. Other forms of carbon black that may be
used with the present invention include, but are not limited to,
carbon black subtypes such as acetylene black, channel black,
furnace black, lamp black and thermal black. Other sources of the
carbon black that may also be used with the present invention
include soot and the material produced by the incomplete combustion
of petroleum products such as FCC tar, coal tar, ethylene cracking
tar as well as fossil fuels, biofuels, biomass and vegetable
oil.
[0042] While the foregoing written description enables one of
ordinary skill to make and use what is considered presently to be
the best mode thereof, those of ordinary skill will understand and
appreciate the existence of variations, combinations, and
equivalents of the specific embodiment, method, and examples
herein. The disclosure should therefore not be limited by the above
described embodiment, method, and examples, but by all embodiments
and methods within the scope and spirit of the disclosure.
* * * * *