U.S. patent number 10,385,186 [Application Number 15/822,575] was granted by the patent office on 2019-08-20 for carbon material precursor and method for producing carbon material using the same.
This patent grant is currently assigned to KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO. The grantee listed for this patent is KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO. Invention is credited to Kenichi Hayashida, Takuya Morishita.
![](/patent/grant/10385186/US10385186-20190820-D00001.png)
United States Patent |
10,385,186 |
Hayashida , et al. |
August 20, 2019 |
Carbon material precursor and method for producing carbon material
using the same
Abstract
A carbon material precursor comprises an acrylamide-based
polymer and at least one addition component selected from the group
consisting of acids and salts thereof; and a method for producing a
carbon material comprises thermally-stabilizing the carbon material
precursor and then carbonizing the carbon material precursor.
Inventors: |
Hayashida; Kenichi (Nagakute,
JP), Morishita; Takuya (Nagakute, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO |
Nagakute-shi, Aichi |
N/A |
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOYOTA CHUO
KENKYUSHO (Aichi, JP)
|
Family
ID: |
62193124 |
Appl.
No.: |
15/822,575 |
Filed: |
November 27, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180148563 A1 |
May 31, 2018 |
|
Foreign Application Priority Data
|
|
|
|
|
Nov 28, 2016 [JP] |
|
|
2016-230452 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08F
120/56 (20130101); C08K 5/09 (20130101); C08K
3/28 (20130101); C08K 3/32 (20130101); C08K
3/38 (20130101); C08K 3/24 (20130101); C01B
32/05 (20170801); C08K 5/092 (20130101); C08K
3/26 (20130101); C08K 3/30 (20130101); C08K
2003/321 (20130101); C08K 2003/3054 (20130101); C08K
2003/324 (20130101); C08K 2003/262 (20130101); C08K
2003/3045 (20130101); C08K 2003/322 (20130101); C08K
2003/329 (20130101) |
Current International
Class: |
C08K
3/26 (20060101); C08K 3/28 (20060101); C08K
3/30 (20060101); C08K 3/32 (20060101); C08K
3/38 (20060101); C01B 32/05 (20170101); C08K
5/092 (20060101); C08F 120/56 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
S37-4405 |
|
Jun 1962 |
|
JP |
|
2015-74844 |
|
Apr 2015 |
|
JP |
|
2016-40419 |
|
Mar 2016 |
|
JP |
|
2016-113726 |
|
Jun 2016 |
|
JP |
|
Primary Examiner: McCracken; Daniel C.
Attorney, Agent or Firm: Oliff PLC
Claims
What is claimed is:
1. A carbon material precursor comprising: an acrylamide-based
polymer containing 50 mol % or more of acrylamide-based monomer
unit; and at least one addition component selected from the group
consisting of acids and salts thereof.
2. The carbon material precursor according to claim 1, wherein the
addition component is at least one selected from the group
consisting of phosphoric acid, polyphosphoric acid, boric acid,
sulfuric acid, nitric acid, carbonic acid, oxalic acid, citric
acid, sulfonic acid, and salts thereof.
3. The carbon material precursor according to claim 1, wherein the
addition component is at least one selected from the group
consisting of ammonium salts and amine salts.
4. The carbon material precursor according to claim 1, wherein the
addition component is the salt of the acid, wherein the acid is at
least one selected from the group consisting of phosphoric acid,
polyphosphoric acid, boric acid, sulfuric acid, nitric acid,
carbonic acid, oxalic acid, citric acid, and sulfonic acid; and the
salt is least one selected from the group consisting of ammonium
salts and amine salts.
5. The carbon material precursor according to claim 1, wherein a
content of the addition component is 0.1 to 20% by mass relative to
100% by mass of the carbon material precursor.
6. A method for producing a carbon material comprising:
thermally-stabilizing the carbon material precursor according to
claim 1; and then carbonizing the carbon material precursor.
7. The method for producing a carbon material according to claim 6,
wherein in the thermal-stabilization, the carbon material precursor
is heated under an oxidizing atmosphere at a temperature of
500.degree. C. or lower.
8. The method for producing a carbon material according to claim 7,
wherein in the carbonization, the thermally-stabilized carbon
material precursor is heated under an inert atmosphere at a
temperature higher than the heating temperature during the
thermal-stabilization.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a carbon material precursor and a
method for producing a carbon material using the same.
Related Background Art
Heretofore, as a method for producing carbon fibers, which are a
type of carbon material, a method including: thermally-stabilizing
a carbon fiber precursor obtained by spinning polyacrylonitrile;
and then carbonizing the carbon fiber precursor has been mainly
employed (for example, Japanese Examined Patent Application
Publication No. Sho 37-4405 (Patent Literature 1), and Japanese
Unexamined Patent Application Publication Nos. 2015-74844 (Patent
Literature 2), 2016-40419 (Patent Literature 3), and 2016-113726
(Patent Literature 4)). There has been a problem that the producing
cost of carbon fibers is high because polyacrylonitrile used in
this method is poorly soluble in inexpensive general-purpose
solvents and hence it is necessary to use expensive solvents such
as dimethyl sulfoxide and N,N-dimethylacetamide for polymerization
and spinning.
Meanwhile, polyacrylamide, which is a water-soluble polymer, is
expected to reduce the producing cost of carbon material because
water, which is inexpensive and has a low environmental load, can
be used as a solvent for polymerization and spinning.
SUMMARY OF THE INVENTION
However, there has been a problem that a carbon material precursor
prepared using polyacrylamide has a low carbonization yield because
the mass of such carbon material precursor decreases to only about
20% when heated to 500.degree. C.
The present invention has been made in view of the above-mentioned
problem of the related art and an object thereof is to provide a
carbon material precursor which contains an acrylamide-based
polymer and has a high carbonization yield, and a method for
producing a carbon material using the same.
The present inventors have made earnest studies to achieve the
object described above and as a result found that the carbonization
yield of a carbon material precursor containing an acrylamide-based
polymer is improved by adding to the acrylamide-based polymer at
least one addition component selected from the group consisting of
acids and salts thereof, which led to the completion of the present
invention.
Specifically, a carbon material precursor of the present invention
comprises: an acrylamide-based polymer; and at least one addition
component selected from the group consisting of acids and salts
thereof. In such a carbon material precursor of the present
invention, the addition component is preferably at least one
selected from the group consisting of phosphoric acid,
polyphosphoric acid, boric acid, sulfuric acid, nitric acid,
carbonic acid, oxalic acid, citric acid, sulfonic acid, and salts
thereof. Meanwhile, the addition component is preferably at least
one selected from the group consisting of ammonium salts and amine
salts. The addition component is further preferably at least one
selected from the group consisting of phosphoric acid,
polyphosphoric acid, boric acid, sulfuric acid, nitric acid,
carbonic acid, oxalic acid, citric acid, sulfonic acid, and salts
thereof, as well as at least one selected from the group consisting
of ammonium salts and amine salts. Furthermore, a content of the
addition component is preferably 0.1 to 20% by mass relative to
100% by mass of the carbon material precursor.
A method for producing a carbon material of the present invention
comprises: thermally-stabilizing such a carbon material precursor
of the present invention; and then carbonizing the carbon material
precursor. In the thermal-stabilization, the carbon material
precursor is preferably heated under an oxidizing atmosphere at a
temperature of 500.degree. C. or lower. In the carbonization, the
thermally-stabilized carbon material precursor is preferably heated
under an inert atmosphere at a temperature higher than the heating
temperature during the thermal-stabilization.
Note that it is not necessarily certain why the carbon material
precursor of the present invention has a high carbonization yield.
The present inventors have surmised as follows. Specifically, it is
presumed that by heating (in particular, thermally-stabilizing) the
carbon material precursor of the present invention, an acid or a
salt thereof which is the addition component functions as a
catalyst for the dehydration reaction of the acrylamide-based
polymer and the structure of the acrylamide-based polymer
transforms to a highly heat-resistant structure, enhancing the
carbonization yield of the carbon material precursor.
The present invention makes it possible to obtain a carbon material
precursor which contains an acrylamide-based polymer and has a high
carbonization yield. In addition, use of such a carbon material
precursor of the present invention makes it possible to safely
produce a carbon material at a low cost.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph illustrating the relationship between the
carbonization yields and the contents of the addition components in
the carbon material precursors obtained in Examples 1 and 2,
Examples 21 to 26, and Comparative Example 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, the present invention is described in detail based on
its preferred embodiments.
First, a carbon material precursor of the present invention is
described. The carbon material precursor of the present invention
contains an acrylamide-based polymer and at least one addition
component selected from the group consisting of acids and salts
thereof. Addition of the addition component to the acrylamide-based
polymer improves the carbonization yield of the carbon material
precursor.
(Acrylamide-based Polymer)
The acrylamide-based polymer used in the present invention is
soluble in at least one of an aqueous solvent (e.g. water, alcohol,
or a mixture solvent thereof) and a water-based mixture solvent
(mixture solvent of the above-described aqueous solvent and an
organic solvent (e.g. tetrahydrofuran)). This makes it possible to
perform wet blending using the aqueous solvent or the water-based
mixture solvent described above in the production of a carbon
material precursor and to safely blend the acrylamide-based polymer
and the addition component homogeneously at a low cost. In
addition, in the forming of the obtained carbon material precursor,
dry forming (dry spinning) or wet forming (wet spinning (including
electrospinning)) can be performed using the aqueous solvent or the
water-based mixture solvent described above, making it possible to
safely produce a carbon material at a low cost. Here, the content
of an organic solvent in the water-based mixture solvent is not
particularly limited as long as the organic solvent blended makes
it possible for the acrylamide-based polymer to solve in the
aqueous solvent which would otherwise be insoluble or poorly
soluble in the aqueous solvent. Moreover, such an acrylamide-based
polymer is preferably an acrylamide-based polymer which is soluble
in the aqueous solvent, and more preferably an acrylamide-based
polymer which is soluble in water (a water-soluble acrylamide-based
polymer), from the viewpoint that a carbon material precursor and a
carbon material can be safely produced at a lower cost.
Such an acrylamide-based polymer may be any of a homopolymer of
acrylamide-based monomer and a copolymer of acrylamide-based
monomer and a different polymerizable monomer as long as the
acrylamide-based polymer is soluble in at least one of the aqueous
solvent and the water-based mixture solvent. Nonetheless, the
acrylamide-based polymer is preferably a polymer containing 50 mol
% or more of acrylamide-based monomer unit, more preferably a
polymer containing 70 mol % or more of acrylamide-based monomer
unit, still more preferably a polymer containing 90 mol % or more
of acrylamide-based monomer unit, and particularly preferably a
homopolymer of acrylamide-based monomer, from the viewpoint that
the acrylamide-based polymer easily solves in at least one of the
aqueous solvent and the water-based mixture solvent (preferably the
aqueous solvent and more preferably water).
Examples of the acrylamide-based monomer include acrylamide,
methacrylamide, N-methylacrylamide, N-methylmethacrylamide,
N-(hydroxymethyl)acrylamide, N-(hydroxymethyl)methacrylamide,
N-(2-hydroxyethyl)acrylamide, N-(2-hydroxyethyl)methacrylamide,
N,N-dimethylacrylamide, and N,N-dimethylmethacrylamide. Such an
acrylamide-based monomer may be used singly or in combination of
two or more kinds. Moreover, acrylamide is preferable among these
acrylamide-based monomers from the viewpoint that acrylamide is
excellent in water solubility.
Examples of the different polymerizable monomer described above
include a vinyl cyanide-based monomer such as acrylonitrile and
methacrylonitrile, a (meth)acrylic acid ester such as methyl
acrylate and methyl methacrylate, an unsaturated carboxylic acid
such as acrylic acid, methacrylic acid and itaconic acid, as well
as salts thereof, an unsaturated carboxylic acid anhydride such as
maleic anhydride and itaconic acid anhydride, an aromatic
vinyl-based monomer such as styrene and a-methylstyrene, a
vinyl-based monomer such as vinyl chloride and vinyl alcohol; and
an olefin-based monomer such as ethylene and propylene. The
different polymerizable monomer mentioned above may be used singly
or in combination of two or more kinds. Moreover, acrylonitrile is
preferable among these polymerizable monomers from the viewpoint
that the carbonization yield of a carbon material precursor is
enhanced.
Known polymerization methods such as solution polymerization and
suspension polymerization can be employed as a method for producing
such an acrylamide-based polymer. When the solution polymerization
is employed, the solvent is not particularly limited as long as the
solvent dissolves the raw material monomer and the obtained
acrylamide-based polymer. Nonetheless, the aqueous solvent (e.g.
water, alcohol, or a mixture solvent thereof) or the water-based
mixture solvent (mixture solvent of the above-described aqueous
solvent and an organic solvent (e.g. tetrahydrofuran)) is
preferably used, the aqueous solvent is more preferably used, and
water is particularly preferably used, from the viewpoint that the
production can be safely performed at a low cost. Furthermore,
polymerization initiators include a radical polymerization
initiator which is soluble in at least one of the aqueous solvent
and the water-based mixture solvent such as
4,4'-azobis(4-cyanovaleric acid), ammonium persulfate, and
potassium persulfate (preferably the aqueous solvent and more
preferably water).
(Addition Component)
The addition component used in the present invention is at least
one selected from the group consisting of acids and salts thereof
and is a component which is soluble in at least one of the aqueous
solvent and the water-based mixture solvent (preferably the aqueous
solvent and more preferably water). This makes it possible to
perform wet blending using the aqueous solvent or the water-based
mixture solvent described above in the production of a carbon
material precursor and to safely blend the acrylamide-based polymer
and the addition component homogeneously at a low cost. In
addition, in the forming of the obtained carbon material precursor,
dry forming (dry spinning) or wet forming (wet spinning (including
electrospinning)) can be performed using the aqueous solvent or the
water-based mixture solvent described above, making it possible to
safely produce a carbon material at a low cost.
Examples of the acid include an inorganic acid such as phosphoric
acid, polyphosphoric acid, boric acid, sulfuric acid, nitric acid,
and carbonic acid, and an organic acid such as oxalic acid, citric
acid, and sulfonic acid. In addition, the salts of such an acid
include a metal salt (e.g. a sodium salt and a potassium salt), an
ammonium salt, and an amine salt, an ammonium salt and an amine
salt are preferable, and an ammonium salt is more preferable. In
particular, among these addition components, phosphoric acid,
polyphosphoric acid, boric acid, sulfuric acid, and ammonium salts
thereof are preferable, phosphoric acid, polyphosphoric acid, boric
acid, and ammonium salts thereof are more preferable, and
phosphoric acid, polyphosphoric acid, an ammonium salt of
phosphoric acid, and an ammonium salt of polyphosphoric acid are
particularly preferable, from the viewpoint that the carbonization
yield of the obtained carbon material precursor is further
improved.
<Carbon Material Precursor>
The carbon material precursor of the present invention contains the
acrylamide-based polymer and the addition component. The content of
the acrylamide-based polymer and the content of the addition
component are not particularly limited in such a carbon material
precursor. Nonetheless, the content of the acrylamide-based polymer
is preferably 80 to 99.9% by mass and the content of the addition
component is preferably 0.1 to 20% by mass, and the content of the
acrylamide-based polymer is more preferably 85 to 99.7% by mass and
the content of the addition component is more preferably 0.3 to 15%
by mass, relative to 100% by mass of the carbon material precursor,
from the viewpoint that the carbonization yield of the carbon
material precursor is further improved. If the content of the
addition component is below the lower limit, the carbonization
yield of the carbon material precursor tends not to be improved. If
the content of the addition component exceeds the lower limit, the
addition effect by the addition component tends not to be
sufficiently obtained.
Such a carbon material precursor of the present invention can be
produced by directly blending (melt blending) the addition
component in the melted acrylamide-based polymer or by dry blending
the acrylamide-based polymer and the addition component. Since the
acrylamide-based polymer and the addition component to be used are
soluble in at least one of the aqueous solvent and the water-based
mixture solvent (preferably the aqueous solvent and more preferably
water), the carbon material precursor is preferably produced by
dissolving (wet blending) the acrylamide-based polymer and the
addition component in the aqueous solvent or the water-based
mixture solvent and then removing the solvent from the obtained
solution. This makes it possible to safely blend the
acrylamide-based polymer and the addition component homogeneously
at a low cost. Moreover, in the wet blending, the aqueous solvent
is more preferably used as the solvent, and water is particularly
preferably used as the solvent, from the viewpoint that the carbon
material precursor can be produced at a lower cost. Furthermore,
the method for removing the solvent is not particularly limited. A
known drying method such as hot air drying, vacuum drying, or
freeze drying can be employed. Hot air drying is preferable among
these methods in view of its simple equipment.
<Method for Producing Carbon Material>
The method for producing the carbon material of the present
invention includes thermally-stabilizing (flameproofing) such a
carbon material precursor of the present invention and then
carbonizing the carbon material precursor.
In the method for producing the carbon material of the present
invention, first, the carbon material precursor of the present
invention is heated under an oxidizing atmosphere (for example, in
the air) (thermal-stabilization). This improves the heat resistance
of the carbon material precursor because the structure of the
acrylamide-based polymer in the carbon material precursor is
changed by acting of the acid or the salt thereof in the carbon
material precursor. The heating temperature during such
thermal-stabilization is preferably 500.degree. C. or less and more
preferably 150 to 300.degree. C. Besides, the heating time during
the thermal-stabilization is not particularly limited, and the
heating exceeding 1 hour can also be performed. Nonetheless, the
heating time is preferably 1 to 60 minutes.
Next, the carbon material precursor thermally-stabilized as
described above (thermally-stabilized carbon material precursor) is
heated under an inert atmosphere (in an inert gas such as nitrogen,
argon, or helium) at a temperature higher than the heating
temperature in the thermal-stabilization (carbonization). This
carbonizes the acrylamide-based polymer in the thermally-stabilized
carbon material precursor to obtain the desired carbon material.
The heating temperature during the carbonization described above is
preferably 500.degree. C. or more and more preferably 1000.degree.
C. or more. In addition, the upper limit of the heating temperature
is preferably 3000.degree. C. or less and more preferably
2000.degree. C. or less. Moreover, although the heating time during
the carbonization is not particularly limited. Nonetheless, the
heating time is preferably 1 to 60 minutes and more preferably 1 to
30 minutes.
Furthermore, in the method for producing the carbon material of the
present invention, it is preferable to form (spin) in advance the
carbon material precursor to be used into a desired shape (for
example, fibrous shape) prior to the thermal-stabilization. Here,
melt forming (melt spinning) using a melted carbon material
precursor may be performed. However, since the acrylamide-based
polymer and the addition component contained in the carbon material
precursor of the present invention are soluble in at least one of
the aqueous solvent and the water-based mixture solvent (preferably
the aqueous solvent and more preferably water), it is preferable to
dissolve the carbon material precursor in the aqueous solvent or
the water-based mixture solvent and then to perform dry forming
(dry spinning), dry-wet forming (dry-wet spinning (dry-jet-wet
spinning)), wet forming (wet spinning), or electrospinning using
the obtained solution. This makes it possible to safely produce the
carbon material precursor in the desired shape at a low cost.
Moreover, as the solvent, the aqueous solvent is preferably used
and water is particularly preferably used from the viewpoint that
the carbon material can be safely produced at a lower cost.
EXAMPLES
Hereinafter, the present invention is described in further detail
based on Examples and Comparative Example. However, the present
invention is not limited to Examples to be described later.
Synthetic Example 1
Dissolved into 190 ml of water was 8.52 g (120 mmol) of acrylamide
(manufactured by Wako Pure Chemical Industries, Ltd. and for
electrophoresis). After that, 366 mg (1.20 mmol) of
4,4'-azobis(4-cyanovaleric acid) was added as a polymerization
initiator, followed by radical polymerization for 3 hours at
70.degree. C. The obtained aqueous solution was introduced into
methanol, followed by precipitation of polyacrylamide.
Polyacrylamide was collected and subjected to vacuum drying.
Example 1
Polyacrylamide obtained in Synthetic Example 1 was dissolved into
water so as to be a concentration of 10% by mass. Phosphoric acid
was added to the obtained polyacrylamide aqueous solution so that
the content of phosphoric acid was 2% by mass relative to 100% by
mass of carbon material precursor. Freeze drying was performed
using the obtained phosphoric acid-containing polyacrylamide
aqueous solution. As a result, a carbon material precursor
containing polyacrylamide and phosphoric acid was obtained.
Example 2
A carbon material precursor was obtained in the same manner as that
in Example 1 except that diammonium hydrogen phosphate was used
instead of the phosphoric acid. Note that the content of diammonium
hydrogen phosphate was 2% by mass relative to 100% by mass of
carbon material precursor.
Example 3
A carbon material precursor was obtained in the same manner as that
in Example 1 except that ammonium dihydrogen phosphate was used
instead of the phosphoric acid. Note that the content of ammonium
dihydrogen phosphate was 2% by mass relative to 100% by mass of
carbon material precursor.
Example 4
A carbon material precursor was obtained in the same manner as that
in Example 1 except that polyphosphoric acid was used instead of
the phosphoric acid. Note that the content of polyphosphoric acid
was 2% by mass relative to 100% by mass of carbon material
precursor.
Example 5
A carbon material precursor was obtained in the same manner as that
in Example 1 except that trisodium phosphate was used instead of
the phosphoric acid. Note that the content of trisodium phosphate
was 2% by mass relative to 100% by mass of carbon material
precursor.
Example 6
A carbon material precursor was obtained in the same manner as that
in Example 1 except that sodium hydrogen phosphate was used instead
of the phosphoric acid. Note that the content of sodium hydrogen
phosphate was 2% by mass relative to 100% by mass of carbon
material precursor.
Example 7
A carbon material precursor was obtained in the same manner as that
in Example 1 except that sodium dihydrogen phosphate was used
instead of the phosphoric acid. Note that the content of sodium
dihydrogen phosphate was 2% by mass relative to 100% by mass of
carbon material precursor.
Example 8
A carbon material precursor was obtained in the same manner as that
in Example 1 except that tripotassium phosphate was used instead of
the phosphoric acid. Note that the content of tripotassium
phosphate was 2% by mass relative to 100% by mass of carbon
material precursor.
Example 9
A carbon material precursor was obtained in the same manner as that
in Example 1 except that dipotassium hydrogen phosphate was used
instead of the phosphoric acid. Note that the content of
dipotassium hydrogen phosphate was 2% by mass relative to 100% by
mass of carbon material precursor.
Example 10
A carbon material precursor was obtained in the same manner as that
in Example 1 except that potassium dihydrogen phosphate was used
instead of the phosphoric acid. Note that the content of potassium
dihydrogen phosphate was 2% by mass relative to 100% by mass of
carbon material precursor.
Example 11
A carbon material precursor was obtained in the same manner as that
in Example 1 except that boric acid was used instead of the
phosphoric acid. Note that the content of boric acid was 2% by mass
relative to 100% by mass of carbon material precursor.
Example 12
A carbon material precursor was obtained in the same manner as that
in Example 1 except that ammonium sulfate was used instead of the
phosphoric acid. Note that the content of ammonium sulfate was 2%
by mass relative to 100% by mass of carbon material precursor.
Example 13
A carbon material precursor was obtained in the same manner as that
in Example 1 except that ammonium hydrogen sulfate was used instead
of the phosphoric acid. Note that the content of ammonium hydrogen
sulfate was 2% by mass relative to 100% by mass of carbon material
precursor.
Example 14
A carbon material precursor was obtained in the same manner as that
in Example 1 except that sodium sulfate was used instead of the
phosphoric acid. Note that the content of sodium sulfate was 2% by
mass relative to 100% by mass of carbon material precursor.
Example 15
A carbon material precursor was obtained in the same manner as that
in Example 1 except that sodium hydrogen sulfate was used instead
of the phosphoric acid. Note that the content of sodium hydrogen
sulfate was 2% by mass relative to 100% by mass of carbon material
precursor.
Example 16
A carbon material precursor was obtained in the same manner as that
in Example 1 except that sodium nitrate was used instead of the
phosphoric acid. Note that the content of sodium nitrate was 2% by
mass relative to 100% by mass of carbon material precursor.
Example 17
A carbon material precursor was obtained in the same manner as that
in Example 1 except that sodium carbonate was used instead of the
phosphoric acid. Note that the content of sodium carbonate was 2%
by mass relative to 100% by mass of carbon material precursor.
Example 18
A carbon material precursor was obtained in the same manner as that
in Example 1 except that sodium hydrogen carbonate was used instead
of the phosphoric acid. Note that the content of sodium hydrogen
carbonate was 2% by mass relative to 100% by mass of carbon
material precursor.
Example 19
A carbon material precursor was obtained in the same manner as that
in Example 1 except that oxalic acid was used instead of the
phosphoric acid. Note that the content of oxalic acid was 2% by
mass relative to 100% by mass of carbon material precursor.
Example 20
A carbon material precursor was obtained in the same manner as that
in Example 1 except that citric acid was used instead of the
phosphoric acid. Note that the content of citric acid was 2% by
mass relative to 100% by mass of carbon material precursor.
Example 21
A carbon material precursor was obtained in the same manner as that
in Example 1 except that the content of phosphoric acid in the
carbon material precursor was changed to 0.5% by mass.
Example 22
A carbon material precursor was obtained in the same manner as that
in Example 1 except that the content of phosphoric acid in the
carbon material precursor was changed to 5% by mass.
Example 23
A carbon material precursor was obtained in the same manner as that
in Example 1 except that the content of phosphoric acid in the
carbon material precursor was changed to 10% by mass.
Example 24
A carbon material precursor was obtained in the same manner as that
in Example 2 except that the content of diammonium hydrogen
phosphate in the carbon material precursor was changed to 0.5% by
mass.
Example 25
A carbon material precursor was obtained in the same manner as that
in Example 2 except that the content of diammonium hydrogen
phosphate in the carbon material precursor was changed to 5% by
mass.
Example 26
A carbon material precursor was obtained in the same manner as that
in Example 2 except that the content of diammonium hydrogen
phosphate in the carbon material precursor was changed to 10% by
mass.
Comparative Example 1
A carbon material precursor was obtained in the same manner as that
in Example 1 except that no addition component was added.
<Measurement of Carbonization Yield>
A differential thermal balance ("TG8120" manufactured by Rigaku
Corporation) was used to heat 3.2 to 3.5 mg of each of the carbon
material precursors obtained in Examples and Comparative Example
from room temperature to 500.degree. C. at a rate of temperature
rise of 10.degree. C./min under a nitrogen stream having a flow
rate of 200 ml/min. In consideration of the influence of water
adsorbed to polyacrylamide, the mass of the carbon material
precursor at 150.degree. C. was taken as a reference to calculate
the carbonization yield of each carbon material precursor by use of
the following formula: Carbonization
Yield[%]=M.sub.500/M.sub.150.times.100
[M.sub.500: Mass of Carbon Material Precursor at 500.degree. C.,
M.sub.150: Mass of Carbon Material Precursor 150.degree. C.]Table 1
indicates the addition components and the carbonization yields of
the carbon material precursors obtained in Examples 1 to 20 and
Comparative Example 1. Also, FIG. 1 illustrates the relationship
between the carbonization yields and the contents of the addition
components in the carbon material precursors obtained in Examples 1
and 2, Examples 21 to 26, and Comparative Example 1.
TABLE-US-00001 TABLE 1 Addition Component Carbonization Yield [%]
Phosphoric Acid 41.2 Diammonium Hydrogen Phosphate 40.3 Ammonium
Dihydrogen Phosphate 41.4 Polyphosphoric Acid 42.1 Trisodium
Phosphate 19.1 Sodium Hydrogen Phosphate 17.2 Sodium Dihydrogen
Phosphate 25.9 Tripotassium Phosphate 19.9 Dipotassium Hydrogen
Phosphate 19.1 Potassium Dihydrogen Phosphate 26.7 Boric Acid 30.1
Ammonium Sulfate 26.1 Ammonium Hydrogen Sulfate 27.5 Sodium Sulfate
17.8 Sodium Hydrogen Sulfate 26.4 Sodium Nitrate 22.7 Sodium
Carbonate 21.7 Sodium Hydrogen Carbonate 18.9 Oxalic Acid 18.1
Citric Acid 19.6 No Additive 15.1
As is apparent from the results shown in Table 1, the carbonization
yield of the carbon material precursor was improved by blending at
least one addition component selected from the group consisting of
acids and salts thereof into the acrylamide-based polymer.
Also, as is apparent from the results shown in FIG. 1, the
carbonization yield of the carbon material precursor was improved
by increasing the content of at least one addition component
selected from the group consisting of acids and salts thereof.
Production Example 1
A thermally-stabilized carbon material precursor was obtained by
heating (thermally-stabilizing) the carbon material precursor
obtained in Example 1 in the air at 250.degree. C. for 30 minutes.
Carbon material was obtained by heating (carbonizing) this
thermally-stabilized carbon material precursor under a nitrogen gas
atmosphere at 1000.degree. C. for 10 minutes.
As described above, the present invention makes it possible to
obtain a carbon material precursor which contains an
acrylamide-based polymer and has a high carbonization yield.
Thus, the method for producing carbon material of the present
invention is useful as a method capable of safely producing carbon
material at a low cost because a carbon material precursor which is
dissolved in an aqueous solvent and exhibits a high carbonization
yield is used.
* * * * *