U.S. patent application number 16/611639 was filed with the patent office on 2020-02-27 for aramid polymerization method using carbon dioxide as solvent.
The applicant listed for this patent is Finings Co. Ltd.. Invention is credited to Jianming SHAO, Nongyue WANG, Guoqiang WEN, Quanzhong ZHAO.
Application Number | 20200062902 16/611639 |
Document ID | / |
Family ID | 59537695 |
Filed Date | 2020-02-27 |
United States Patent
Application |
20200062902 |
Kind Code |
A1 |
WANG; Nongyue ; et
al. |
February 27, 2020 |
ARAMID POLYMERIZATION METHOD USING CARBON DIOXIDE AS SOLVENT
Abstract
Disclosed herein is a method for aramid polymerization using
carbon dioxide as a solvent, comprising reacting phenylenediamine
with benzenedicarbonyl dichloride, wherein an acid-binding agent is
added to the reaction system, and liquid carbon dioxide and/or a
supercritical carbon dioxide fluid is used as a reaction solvent.
The method of the present application is environmentally friendly,
saves resources, has low cost, and is safe for production and
suitable for industrial production. The polycondensate obtained in
the present application has a controllable molecular weight, a good
product quality, and an intrinsic viscosity .eta.inh of 8-9 dl/g.
The yield in the aramid condensation stage can reach 98%, and the
recovery rate of the aramid condensation solvent is higher than
90%.
Inventors: |
WANG; Nongyue; (Huai'an
City, Jiangsu, CN) ; WEN; Guoqiang; (Huai'an City,
Jiangsu, CN) ; ZHAO; Quanzhong; (Huai'an City,
Jiangsu, CN) ; SHAO; Jianming; (Huai'an City,
Jiangsu, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Finings Co. Ltd. |
Huai'an City, Jiangsu |
|
CN |
|
|
Family ID: |
59537695 |
Appl. No.: |
16/611639 |
Filed: |
March 28, 2018 |
PCT Filed: |
March 28, 2018 |
PCT NO: |
PCT/CN2018/080832 |
371 Date: |
November 7, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 69/32 20130101;
Y02P 20/544 20151101; C08G 69/04 20130101; C08G 69/28 20130101 |
International
Class: |
C08G 69/32 20060101
C08G069/32; C08G 69/28 20060101 C08G069/28 |
Foreign Application Data
Date |
Code |
Application Number |
May 15, 2017 |
CN |
201710337418.5 |
Claims
1. A method for aramid polymerization using carbon dioxide as a
solvent, comprising reacting phenylenediamine with
benzenedicarbonyl dichloride, wherein an acid-binding agent is
added to the reaction system, and liquid carbon dioxide, a
supercritical carbon dioxide fluid, or both, is used as a reaction
solvent.
2. The method according to claim 1, wherein when the liquid carbon
dioxide is used as a reaction solvent, the reaction temperature is
lower than the critical temperature of CO.sub.2 and higher than the
triple-point temperature of CO.sub.2, and during the reaction, a
pressure at which the carbon dioxide is maintained in a liquid
state at the reaction temperature is maintained.
3. The method according to claim 1, wherein when supercritical
carbon dioxide fluid is used as a reaction solvent, the reaction
environment is maintained above the critical temperature and the
critical pressure of CO.sub.2, the reaction temperature is higher
than 31.1.degree. C., and the reaction pressure is greater than
7.29 MPa.
4. The method according to claim 1, wherein when supercritical
carbon dioxide fluid is used as a reaction solvent, the reaction
temperature is between 31.1 and 120.degree. C., and the pressure is
between 7.29 and 50 MPa.
5. The method according to claim 1, wherein the process using
liquid carbon dioxide and supercritical carbon dioxide fluid as
reaction solvents, further comprising initially controlling the
carbon dioxide in a liquid state; then the carbon dioxide becomes
supercritical when the heat released from the reaction of
phenylenediamine with benzenedicarbonyl dichloride increases the
temperature of the solution to exceed the critical temperature of
carbon dioxide, and the pressure is also greater than the critical
pressure, and continuing to complete the reaction in the
supercritical state.
6. The method according to claim 1, wherein molar ratio of the
phenylenediamine to the benzenedicarbonyl dichloride is
(0.95-1.0):(0.95-1.0).
7. The method according to claim 1, wherein the amount of the
acid-binding agent used is 0.95-1.2 times the theoretical
stoichiometric amount required to neutralize the generated hydrogen
chloride.
8. The method according to claim 1, wherein the acid-binding agent
is an organic base, an inorganic base or both.
9. The method according to claim 8, wherein the acid-binding agent
is a mixture of the organic base and the inorganic base.
10. The method according to claim 9, wherein when the acid-binding
agent is a mixture of the organic base and the inorganic base, the
amount of the organic base used is 10-80% of the total amount
sufficient to neutralize the generated hydrogen chloride.
11. The method according to claim 9, wherein the inorganic base in
the acid-binding agent is an alkali metal, alkaline earth metal
carbonate, bicarbonate, or a combination thereof.
12. The method according to claim 1, wherein the phenylenediamine
and the benzenedicarbonyl dichloride are separately dissolved in
the solvent to prepare a solution containing phenylenediamine and a
solution containing benzenedicarbonyl dichloride.
13. The method according to claim 12, wherein the acid-binding
agent and the phenylenediamine are co-dissolved in the solvent to
prepare a mixture liquid containing acid-binding
agent-phenylenediamine-solvent; and then the mixture liquid of the
acid-binding agent-phenylenediamine-solvent is reacted with the
solution containing benzenedicarbonyl dichloride.
14. The method according to claim 12, wherein when the solution
containing phenylenediamine is prepared, the amount of the solvent
used is 5-50 times the mass of the phenylenediamine; and when the
solution containing benzenedicarbonyl dichloride is prepared, the
amount of the solvent used is 5-50 times the mass of the
benzenedicarbonyl dichloride.
15. The method according to claim 1, wherein the molar ratio of the
phenylenediamine to the benzenedicarbonyl dichloride is 1:1.
16. The method according to claim 1, wherein the amount of the
acid-binding agent used is 1.01-1.1 times the theoretical
stoichiometric amount required to neutralize the generated hydrogen
chloride.
17. The method according to claim 9, wherein when the acid-binding
agent is a mixture of the organic base and the inorganic base, the
amount of the organic base used is 30-60% of the total amount
sufficient to neutralize the generated hydrogen chloride.
Description
TECHNICAL FIELD
[0001] The present invention belongs to the field of organic
polymer compounds, and relates to a method for aramid
polymerization, in particular to a method for aramid polymerization
using carbon dioxide as a solvent.
BACKGROUND OF THE INVENTION
[0002] Aramids 1313 and 1414 are polyamide fibers that are formed
by polycondensation of (m- or p-) benzenedicarbonyl dichloride with
(m- or p-) phenylenediamine followed by solution spinning. They are
mainly used for protection against atomic radiation, materials for
high-altitude and high-speed flight, etc., and can also be used for
tire meridian with special requirements, high temperature-resistant
materials for clothing, honeycomb parts, high temperature pipeline,
aircraft fuel tank, firewall, reverse osmosis membrane, hollow
fiber, etc.
[0003] The main methods for synthesizing aramid at home and abroad
include: low-temperature solution polycondensation method, direct
polycondensation method, ionic liquid polycondensation method, and
fuming sulfuric acid polycondensation method. At present, only the
low-temperature solution polycondensation method has been
industrialized, and other methods have not been reported for
industrialization. The low-temperature solution polycondensation
method was first invented by DuPont Co., US in 1972, and has been
used until now. The theory and industrialization of this synthesis
method have been thoroughly studied, and the obtained polymers can
be adapted to various applications of high, medium and low grades.
Due to good dissolving capacity for monomers and polymers,
hexamethylphosphoric triamide (HMPA) was often used in the early
years. For example, U.S. Pat. No. 3,850,888 and U.S. Pat. No.
3,884,881 disclose low-temperature polycondensation methods using
HMPA as a solvent. However, HMPA was later found to be
carcinogenic, so it was gradually replaced with N-methylpyrrolidone
(NMP). EP0229714 and U.S. Pat. No. 4,737,571 both disclose
low-temperature polycondensation methods using NMP as a solvent.
Since NMP is inferior to HMPA in terms of dissolving capacity, a
salt, such as lithium chloride, calcium chloride, or the like, is
generally added to improve the solubility. Since preparation of
aramid by low-temperature solution polycondensation method has been
successfully used in the industry, most of current studies are
focused on further optimization of the reaction process, reduction
of the cost, etc., such as in CN106046364A, CN102731778B, etc.
[0004] Although the low-temperature solution polycondensation
method using NMP as a solvent is the main method for synthesizing
commercial aramid, there are some problems in this method: (1) The
product quality is unstable. Because NMP is a substance that easily
absorbs water, and the reaction system requires a moisture content
of less than 200 ppm, the presence of moisture is fatal to the
reaction, resulting in a sharp decrease in molecular weight.
Moreover, the dehydration of NMP and the control of moisture in the
reaction system are relatively difficult. (2) The solvent is
difficult to recover and the production sewage is difficult to
treat. After the reaction, the solvent NMP needs to be washed away
with water. Since NMP is easily soluble in water and difficult to
separate, the solvent is difficult to recover. In addition, the
organic base-based acid absorbent such as pyridine added to the
reaction system is also unfavorable to the recovery of the NMP
solvent.
Technical Problems
[0005] The problems to be solved by the present invention are
difficult control of product quality and difficult recovery of the
solvent in current methods for polymerization and synthesis of
aramid, and a method for aramid polymerization using carbon dioxide
as a solvent is provided herein.
Solutions to the Problems
Technical Solutions
[0006] In order to solve the above problems, the present invention
employs the following technical solution:
[0007] A method for aramid polymerization using carbon dioxide as a
solvent, comprising reacting phenylenediamine with
benzenedicarbonyl dichloride, wherein an acid-binding agent is
added to the reaction system, and liquid carbon dioxide and/or a
supercritical carbon dioxide fluid is used as a reaction
solvent.
[0008] Those skilled in the art can understand how to place CO2 in
a liquid state or in a supercritical state.
[0009] Preferably, when liquid carbon dioxide is used as a reaction
solvent, the reaction temperature is lower than the critical
temperature of CO2 and higher than the triple-point temperature of
CO2, and the reaction temperature is between -56.6 and 31.1.degree.
C.; and during the reaction, it is necessary to maintain a pressure
at which the carbon dioxide is maintained in a liquid state at the
reaction temperature, preferably, a pressure of 0.55-45 MPa.
[0010] When liquid carbon dioxide is used as a reaction solvent in
the present application, the reaction temperature can be any value
in the range of -56.6 to 31.1.degree. C. or in a range defined by a
combination of any values within the range, for example,
-55.degree. C., -50.degree. C., -45.degree. C., -40.degree. C.,
-35.degree. C., -30.degree. C., -25.degree. C., -20.degree. C.,
-15.degree. C., -10.degree. C., -5.degree. C., 0.degree. C.,
5.degree. C., 10.degree. C., 15.degree. C., 20.degree. C.,
25.degree. C., 30.degree. C., -50 to -5.degree. C., -20 to
5.degree. C., -10 to -5.degree. C., 0 to 25.degree. C., or -15 to
-25.degree. C. During the reaction, it is necessary to maintain a
pressure at which the carbon dioxide is maintained in a liquid
state at the reaction temperature, preferably, a pressure of
0.55-45 MPa, as long as the pressure can make carbon dioxide in a
liquid state at the temperature. The pressure can be any value in
the range of 0.55 to 45 MPa or in a range defined by a combination
of any values within the range, for example, 1 MPa, 5 MPa, 10 MPa,
15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45MPa, 5-20 MPa,
10-20 MPa, 15-30 MPa, 15-40 MPa, or 30-40 MPa.
[0011] When supercritical carbon dioxide fluid is used as a
reaction solvent, the reaction environment is maintained above the
critical temperature and the critical pressure of CO2, i.e., the
reaction temperature is higher than 31.1.degree. C., and the
reaction pressure is greater than 7.29 MPa. Preferably, the
reaction temperature is between 31.1 and 120.degree. C., and the
pressure is between 7.29 and 50 MPa.
[0012] Preferably, when supercritical carbon dioxide fluid is used
as a reaction solvent in the present application, the reaction
temperature can be any value in the range of 31.1 to 120.degree. C.
or in a range defined by a combination of any values within the
range, for example, 35.degree. C., 40.degree. C., 45.degree. C.,
50.degree. C., 55.degree. C., 60.degree. C., 65.degree. C.,
70.degree. C., 75.degree. C., 80.degree. C., 85.degree. C.,
90.degree. C., 95.degree. C., 100.degree. C., 105.degree. C.,
110.degree. C., 115.degree. C., 120.degree. C., 40-55.degree. C.,
45-60.degree. C., 50-70.degree. C., 60-100.degree. C.,
80-120.degree. C., 32-120.degree. C., or the like. The pressure can
be any value in the range of 7.29 to 50 MPa or in a range defined
by a combination of any values within the range, for example, 8
MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45
MPa, 50 MPa, 10-20 MPa, 15-30 MPa, 25-45 MPa, or 8-50 MPa.
[0013] The use of liquid carbon dioxide and supercritical carbon
dioxide as solvents, as used herein, refers to use of the heat
released from the reaction or an input or output of external heat
to cause transition of carbon dioxide between the liquid state and
the supercritical state, such that the entire reaction process is
performed in both liquid carbon dioxide and supercritical carbon
dioxide.
[0014] In the preparation process of the invention, the carbon
dioxide can be initially controlled in a liquid state, then the
carbon dioxide becomes supercritical when the heat released from
the reaction of phenylenediamine with benzenedicarbonyl dichloride
increases the temperature of the solution to exceed the critical
temperature of carbon dioxide, and the pressure is also greater
than the critical pressure of 7.29 MPa, and then the reaction can
be continued to complete in the supercritical state.
[0015] The molar ratio of the phenylenediamine to the
benzenedicarbonyl dichloride is 0.95-1.0: 0.95-1.0. Preferably, the
molar ratio of the phenylenediamine to the benzenedicarbonyl
dichloride needs to be strictly controlled to be 1:1; otherwise,
the polymerization reaction can be easily terminated, which affects
the product quality.
[0016] Preferably, the acid-binding agent is an organic base and/or
an inorganic base.
[0017] Preferably, the acid-binding agent is added to the reaction
in an amount 0.95-1.2 times the theoretical stoichiometric amount
required to neutralize the generated hydrogen chloride according to
the amounts of phenylenediamine and benzenedicarbonyl dichloride.
Preferably, the acid-binding agent is added to the reactor in an
amount 1.01-1.1 times the theoretical stoichiometric amount
required to neutralize the generated hydrogen chloride according to
the amounts of phenylenediamine and benzenedicarbonyl dichloride.
For example, when 1 mol of hydrogen chloride will be produced
theoretically according to the amounts of phenylenediamine and
benzenedicarbonyl dichloride, 0.95-1.2 mol of triethylamine,
preferably a slight excess, i.e., 1.01-1.1 mol of triethylamine
should be used.
[0018] The organic base is an amine, preferably a tertiary amine,
i.e., a compound having a tertiary amino group, for example,
triethylamine, trimethylamine, tripropylamine, tributylamine,
dimethylisopropylamine, dimethylcyclohexylamine, pyridine,
4-methylmorpholine, 4-ethylmorpholine, 4-butylmorpholine,
N-methylpyrrolidine, N-ethylpyrrolidine, N-methylpiperidine,
N-ethylpiperidine, N-methylindole, N-ethylindole, N-methylpyrrole,
or the like.
[0019] The inorganic base can be, without any limitation, a
well-known inorganic base, for example, sodium carbonate, calcium
hydroxide, calcium carbonate, potassium hydroxide, lithium
hydroxide, potassium carbonate, lithium carbonate, sodium
bicarbonate, magnesium hydroxide, potassium bicarbonate, lithium
bicarbonate, magnesium carbonate, sodium hydroxide, or the
like.
[0020] It was found during the study that when the acid-binding
agent is a mixture of an organic base and an inorganic base, in
particular, when the amount of the organic base used is at least
10-80% of the total amount sufficient to neutralize the hydrogen
chloride generated during the reaction, the reaction is more stable
and controllable, and contributes to an increase in the molecular
weight of the polymer. Therefore, it is further preferred that the
acid-binding agent is a mixture of an organic base and an inorganic
base, and the amount of the organic base used is 10-80% of the
total amount sufficient to neutralize the generated hydrogen
chloride; and further preferably, the amount of the organic base
used is 30-60% of the total amount sufficient to neutralize the
generated hydrogen chloride.
[0021] Further preferably, the inorganic base in the acid-binding
agent is an alkali metal and/or alkaline earth metal carbonate
and/or bicarbonate, such as calcium carbonate, magnesium carbonate,
potassium bicarbonate, lithium bicarbonate, or the like. The alkali
metal chloride and/or alkaline earth metal chloride, such as
lithium chloride, calcium chloride, or the like, generated during
neutralization of hydrogen chloride by the alkali metal and/or
alkali metal carbonate and/or bicarbonate, can further improve the
solubility of the polymer in the solvent, and is beneficial to an
increase in the molecular weight of the polymer. The carbon dioxide
generated during the neutralization of hydrogen chloride can
further participate in the reaction as a solvent.
[0022] Preferably, the method of the present invention comprises
separately dissolving phenylenediamine and benzenedicarbonyl
dichloride in a solvent to prepare a solution containing
phenylenediamine and a solution containing benzenedicarbonyl
dichloride.
[0023] Preferably, the acid-binding agent and the phenylenediamine
are co-dissolved in a solvent to prepare a mixture liquid
containing acid-binding agent-phenylenediamine-solvent. Further,
the mixture liquid of acid-binding agent-phenylenediamine-solvent
reacts with the solution containing benzenedicarbonyl
dichloride.
[0024] Preferably, when a solvent is used to dissolve the
phenylenediamine, the solvent is used in an amount 5-50 times the
mass of the phenylenediamine; and when a solvent is used to
dissolve the benzenedicarbonyl dichloride, the solvent is used in
an amount 5-50 times the mass of the benzenedicarbonyl
dichloride.
[0025] In the method described herein, after the reaction is
completed, the liquid CO2 or supercritical CO2 fluid can be
converted to a gaseous state by a change in temperature and/or
pressure. The resultant CO2 in a gaseous state can be subjected to
further compression and condensation, and recovered for
recycling.
[0026] In particular, the inventors have discovered that when
liquid CO2 or a supercritical CO2 fluid, especially a supercritical
CO2 fluid in a high temperature and high pressure state, is used as
a solvent, the transition to a gaseous state can be a process of
gradual change by controlling the temperature and/or pressure, for
example, gradually increasing the temperature, and gradually
decreasing the pressure, or the like. Those skilled in the art can
clearly understand the meaning of the gradual change of the state.
A certain amount of heat can be provided to the reaction vessel,
e.g., by means of jacket heating, heat preservation, or the like,
or a regulating valve can be used, in order to prevent a rapid and
sharp temperature drop, which can result in conversion of CO2 to
solid dry ice, thereby blocking the valve, pipeline, etc.
[0027] The supercritical CO2 fluid as described herein refers to a
state when the temperature and pressure of CO2 are higher than its
critical temperature and critical pressure.
[0028] The triple-point of CO2 as described herein refers to a
temperature and a pressure value at which three phases of CO2
(i.e., gas phase, liquid phase, and solid phase) coexist.
[0029] The aramid as described herein is para-aramid or
meta-aramid. Correspondingly, the polymerization method as
described herein refers to a reaction of p-phenylenediamine with
p-benzenedicarbonyl dichloride, or a reaction of m-phenylenediamine
with m-benzenedicarbonyl dichloride.
BENEFICIAL EFFECTS OF THE INVENTION
Beneficial Effects
[0030] (1) The use of liquid carbon dioxide or supercritical carbon
dioxide fluid as a solvent instead of a conventional solvent will
not cause contamination of the product. The solvent is inexpensive,
readily available and non-toxic. Separation of the product from the
solvent can be achieved only by changing the temperature and/or
pressure. The method is environmentally friendly, saves resources,
has low cost, and is safe for production and suitable for
industrial production.
[0031] (2) The polycondensate obtained in the present application
has a controllable molecular weight, a good product quality, and an
intrinsic viscosity .eta.inh of 8-9 dl/g. The yield in the aramid
condensation stage can reach 98%, and the recovery rate of the
aramid condensation solvent is higher than 90%.
EXAMPLES
Embodiments of the Invention
[0032] In the following Examples, the intrinsic viscosity is
measured on a polycondensate formulated at a concentration of 0.2
g/25 ml of H2SO4 in 98% sulfuric acid as a solvent, by an Ubbelohde
viscometer at a temperature of 23.degree. C., and the unit of the
intrinsic viscosity .eta.inh is dl/g (deciliter/gram).
Example 1
[0033] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
9.33 g of the acid-binding agent triethylamine. The original gas
was replaced with nitrogen, and liquid carbon dioxide was injected.
The reactor was kept at a temperature of 25.degree. C., and a
pressure of no less than 7 MPa. Upon the substances in the pressure
reactor were dissolved, a p-phenylenediamine-triethylamine-liquid
carbon dioxide mixture liquid was prepared. To another pressure
reactor equipped with a stirrer and connected to a dry nitrogen
tube was added 9.02 g of p-benzenedicarbonyl dichloride. The
original gas was replaced with nitrogen, and liquid carbon dioxide
was injected. The reactor was kept at a temperature of 25.degree.
C., and a pressure of no less than 7 MPa. Upon the substance in the
pressure reactor was dissolved, a solution of p-benzenedicarbonyl
dichloride in liquid carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in liquid carbon dioxide was added
to the p-phenylenediamine-triethylamine-liquid carbon dioxide
mixture liquid while rapid stirring. The heat released from the
reaction increased the temperature of the solution to exceed the
critical temperature of carbon dioxide, and caused the pressure to
exceed the critical pressure of carbon dioxide, resulting in a
supercritical state of carbon dioxide, in which the solubility of
an aramid polycondensate was increased. The stirring was continued
until the reaction was completed. Water was added to the pressure
reactor. The CO2 gas was gradually discharged, and compressed and
condensed again for recovery. After centrifugation, filtration, and
removal of the residual acid-binding agent and other substances by
washing, an aramid polycondensate was obtained upon drying.
[0034] The resultant dried aramid polycondensate was measured. The
intrinsic viscosity .eta.inh of the polycondensate was 8.25 dl/g,
the yield in the aramid condensation stage was 97%, and the
recovery rate of CO2 was higher than 90%.
Example 2
[0035] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
3.45 g of the acid-binding agent calcium hydroxide. The original
gas was replaced with nitrogen, and liquid carbon dioxide was
injected. The reactor was kept at a temperature of 15.degree. C.,
and a pressure of no less than 6 MPa. Upon the substances in the
pressure reactor were dissolved, a p-phenylenediamine-calcium
hydroxide-liquid carbon dioxide mixture liquid was prepared. To
another pressure reactor equipped with a stirrer and connected to a
dry nitrogen tube was added 9.02 g of p-benzenedicarbonyl
dichloride. The original gas was replaced with nitrogen, and liquid
carbon dioxide was injected. The reactor was kept at a temperature
of 15.degree. C., and a pressure of no less than 6 MPa. Upon the
substance in the pressure reactor was dissolved, a solution of
p-benzenedicarbonyl dichloride in liquid carbon dioxide was
prepared. The solution of p-benzenedicarbonyl dichloride in liquid
carbon dioxide was added to the p-phenylenediamine-calcium
hydroxide-liquid carbon dioxide mixture liquid while rapid
stirring. The heat released from the reaction increased the
temperature of the solution to exceed the critical temperature of
carbon dioxide, and an increased pressure was applied
simultaneously so that the pressure exceeded the critical pressure
of carbon dioxide, resulting in a supercritical state of carbon
dioxide, in which the solubility of an aramid polycondensate was
increased. The stirring was continued until the reaction was
completed. Water was added to the pressure reactor. The CO2 gas was
gradually discharged, and compressed and condensed again for
recovery. After centrifugation, filtration, and removal of the
residual acid-binding agent and other substances by washing, an
aramid polycondensate was obtained upon drying.
[0036] The resultant dried aramid polycondensate was measured. The
intrinsic viscosity .eta.inh of the polycondensate was 8.01 dl/g,
the yield in the aramid condensation stage was 96.6%, and the
recovery rate of CO2 was higher than 90%.
Example 3
[0037] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
2.69 g of triethylamine and 2.36 g of calcium hydroxide as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was injected. The reactor was kept at a
temperature of 28.degree. C., and a pressure of no less than 7 MPa.
Upon the substances in the pressure reactor were dissolved, a
p-phenylenediamine-triethylamine-calcium hydroxide-liquid carbon
dioxide mixture liquid was prepared. To another pressure reactor
equipped with a stirrer and connected to a dry nitrogen tube was
added 9.02 g of p-benzenedicarbonyl dichloride. The original gas
was replaced with nitrogen, and liquid carbon dioxide was injected.
The reactor was kept at a temperature of 28.degree. C., and a
pressure of no less than 7 MPa. Upon the substance in the pressure
reactor was dissolved, a solution of p-benzenedicarbonyl dichloride
in liquid carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in liquid carbon dioxide was added
to the p-phenylenediamine-triethylamine-calcium hydroxide-liquid
carbon dioxide mixture liquid while rapid stirring. The heat
released from the reaction increased the temperature of the
solution to exceed the critical temperature of carbon dioxide, and
caused the pressure to exceed the critical pressure of carbon
dioxide, resulting in a supercritical state of carbon dioxide, in
which the solubility of an aramid polycondensate was increased. The
stirring was continued until the reaction was completed. Water was
added to the pressure reactor. The CO2 gas was gradually
discharged, and compressed and condensed again for recovery. After
centrifugation, filtration, and removal of the residual
acid-binding agents and other substances by washing, an aramid
polycondensate was obtained upon drying.
[0038] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.8 dl/g, the yield in
the aramid condensation stage was 98%, and the recovery rate of CO2
was higher than 90%.
Example 4
[0039] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
2.69 g of triethylamine and 2.36 g of calcium hydroxide as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was injected. The reactor was kept at a
temperature of -15.degree. C., and a pressure of no less than 3
MPa. Upon the substances in the pressure reactor were dissolved, a
p-phenylenediamine-triethylamine-calcium hydroxide-liquid carbon
dioxide mixture liquid was prepared. To another pressure reactor
equipped with a stirrer and connected to a dry nitrogen tube was
added 9.02 g of p-benzenedicarbonyl dichloride. The original gas
was replaced with nitrogen, and liquid carbon dioxide was injected.
The reactor was kept at a temperature of -15.degree. C., and a
pressure of no less than 3 MPa. Upon the substance in the pressure
reactor was dissolved, a solution of p-benzenedicarbonyl dichloride
in liquid carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in liquid carbon dioxide was added
to the p-phenylenediamine-triethylamine-calcium hydroxide-liquid
carbon dioxide mixture liquid while rapid stirring. The carbon
dioxide was maintained in a liquid state throughout the reaction.
The stirring was continued until the reaction was completed. Water
was added to the pressure reactor. The CO2 gas was gradually
discharged, and compressed and condensed again for recovery. After
centrifugation, filtration, and removal of the residual
acid-binding agents and other substances by washing, an aramid
polycondensate was obtained upon drying.
[0040] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.4 dl/g, the yield in
the aramid condensation stage was 97.3%, and the recovery rate of
CO2 was higher than 90%.
Example 5
[0041] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of m-phenylenediamine, and
4.49 g of triethylamine and 1.87 g of calcium hydroxide as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was injected. The reactor was kept at a
temperature of -25.degree. C., and a pressure of no less than 2
MPa. Upon the substances in the pressure reactor were dissolved, an
m-phenylenediamine-triethylamine-calcium hydroxide-liquid carbon
dioxide mixture liquid was prepared. To another pressure reactor
equipped with a stirrer and connected to a dry nitrogen tube was
added 9.02 g of m-benzenedicarbonyl dichloride. The original gas
was replaced with nitrogen, and liquid carbon dioxide was injected.
The reactor was kept at a temperature of -25.degree. C., and a
pressure of no less than 2 MPa. Upon the substance in the pressure
reactor was dissolved, a solution of m-benzenedicarbonyl dichloride
in liquid carbon dioxide was prepared. The solution of
m-benzenedicarbonyl dichloride in liquid carbon dioxide was added
to the m-phenylenediamine-triethylamine-calcium hydroxide-liquid
carbon dioxide mixture liquid while rapid stirring. The carbon
dioxide was maintained in a liquid state throughout the reaction.
The stirring was continued until the reaction was completed. Water
was added to the pressure reactor. The CO2 gas was gradually
discharged, and compressed and condensed again for recovery. After
centrifugation, filtration, and removal of the residual
acid-binding agents and other substances by washing, an aramid
polycondensate was obtained upon drying.
[0042] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.45 dl/g, the yield
in the aramid condensation stage was 97.6%, and the recovery rate
of CO2 was higher than 90%.
Example 6
[0043] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
6.28 g of triethylamine and 1.73 g of calcium carbonate as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was injected. The reactor was kept at a
temperature of 5.degree. C., and a pressure of no less than 4 MPa.
Upon the substances in the pressure reactor were dissolved, a
p-phenylenediamine-triethylamine-calcium carbonate-liquid carbon
dioxide mixture liquid was prepared. To another pressure reactor
equipped with a stirrer and connected to a dry nitrogen tube was
added 9.02 g of p-benzenedicarbonyl dichloride. The original gas
was replaced with nitrogen, and liquid carbon dioxide was injected.
The reactor was kept at a temperature of 5.degree. C., and a
pressure of no less than 4 MPa. Upon the substance in the pressure
reactor was dissolved, a solution of p-benzenedicarbonyl dichloride
in liquid carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in liquid carbon dioxide was added
to the p-phenylenediamine-triethylamine-calcium carbonate-liquid
carbon dioxide mixture liquid while rapid stirring. The heat
released from the reaction increased the temperature of the
solution to exceed the critical temperature of carbon dioxide, and
the pressure was simultaneously made to exceed the critical
pressure of carbon dioxide, resulting in a supercritical state of
carbon dioxide, in which the solubility of an aramid polycondensate
was increased. The stirring was continued until the reaction was
completed. Water was added to the pressure reactor. The CO2 gas was
gradually discharged, and compressed and condensed again for
recovery. After centrifugation, filtration, and removal of the
residual acid-binding agents and other substances by washing, an
aramid polycondensate was obtained upon drying.
[0044] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.92 dl/g, the yield
in the aramid condensation stage was 98%, and the recovery rate of
CO2 was higher than 90%.
Example 7
[0045] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
4.49 g of triethylamine and 1.54 g of calcium hydroxide as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was injected. The reactor was kept at a
temperature of -25.degree. C., and a pressure of no less than 2
MPa. Upon the substances in the pressure reactor were dissolved, a
p-phenylenediamine-triethylamine-calcium hydroxide-liquid carbon
dioxide mixture liquid was prepared. To another pressure reactor
equipped with a stirrer and connected to a dry nitrogen tube was
added 9.02 g of p-benzenedicarbonyl dichloride. The original gas
was replaced with nitrogen, and liquid carbon dioxide was injected.
The reactor was kept at a temperature of -25.degree. C., and a
pressure of no less than 2 MPa. Upon the substance in the pressure
reactor was dissolved, a solution of p-benzenedicarbonyl dichloride
in liquid carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in liquid carbon dioxide was added
to the p-phenylenediamine-triethylamine-calcium hydroxide-liquid
carbon dioxide mixture liquid while rapid stirring. The carbon
dioxide was maintained in a liquid state throughout the reaction.
The stirring was continued until the reaction was completed. Water
was added to the pressure reactor. The CO2 gas was gradually
discharged, and compressed and condensed again for recovery. After
centrifugation, filtration, and removal of the residual
acid-binding agents and other substances by washing, an aramid
polycondensate was obtained upon drying.
[0046] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.39 dl/g, the yield
in the aramid condensation stage was 97.3%, and the recovery rate
of CO2 was higher than 90%.
Example 8
[0047] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
2.61 g of triethylamine and 2.3 g of calcium hydroxide as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was injected. The reactor was kept at a
temperature of 25.degree. C., and a pressure of no less than 7 MPa.
Upon the substances in the pressure reactor were dissolved, a
p-phenylenediamine-triethylamine-calcium hydroxide-liquid carbon
dioxide mixture liquid was prepared. To another pressure reactor
equipped with a stirrer and connected to a dry nitrogen tube was
added 8.75 g of p-benzenedicarbonyl dichloride. The original gas
was replaced with nitrogen, and liquid carbon dioxide was injected.
The reactor was kept at a temperature of 25.degree. C., and a
pressure of no less than 7 MPa. Upon the substance in the pressure
reactor was dissolved, a solution of p-benzenedicarbonyl dichloride
in liquid carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in liquid carbon dioxide was added
to the p-phenylenediamine-triethylamine-calcium hydroxide-liquid
carbon dioxide mixture liquid while rapid stirring. The heat
released from the reaction increased the temperature of the
solution to exceed the critical temperature of carbon dioxide, and
the pressure was simultaneously made to exceed the critical
pressure of carbon dioxide, resulting in a supercritical state of
carbon dioxide, in which the solubility of an aramid polycondensate
was increased. The stirring was continued until the reaction was
completed. Water was added to the pressure reactor. The CO2 gas was
gradually discharged, and compressed and condensed again for
recovery. After centrifugation, filtration, and removal of the
residual acid-binding agents and other substances by washing, an
aramid polycondensate was obtained upon drying.
[0048] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.05 dl/g, the yield
in the aramid condensation stage was 96%, and the recovery rate of
CO2 was higher than 90%.
Example 9
[0049] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
3.59 g of triethylamine and 2.07 g of calcium hydroxide as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was injected. The reactor was kept at a
temperature of 25.degree. C., and a pressure of no less than 7 MPa.
Upon the substances in the pressure reactor were dissolved, a
p-phenylenediamine-triethylamine-calcium hydroxide-liquid carbon
dioxide mixture liquid was prepared. To another pressure reactor
equipped with a stirrer and connected to a dry nitrogen tube was
added 9.2 g of p-benzenedicarbonyl dichloride. The original gas was
replaced with nitrogen, and liquid carbon dioxide was injected. The
reactor was kept at a temperature of 25.degree. C., and a pressure
of no less than 7 MPa. Upon the substance in the pressure reactor
was dissolved, a solution of p-benzenedicarbonyl dichloride in
liquid carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in liquid carbon dioxide was added
to the p-phenylenediamine-triethylamine-calcium hydroxide-liquid
carbon dioxide mixture liquid while rapid stirring. The heat
released from the reaction increased the temperature of the
solution to exceed the critical temperature of carbon dioxide, and
the pressure was simultaneously made to exceed the critical
pressure of carbon dioxide, resulting in a supercritical state of
carbon dioxide, in which the solubility of an aramid polycondensate
was increased. The stirring was continued until the reaction was
completed. Water was added to the pressure reactor. The CO.sub.2
gas was gradually discharged, and compressed and condensed again
for recovery. After centrifugation, filtration, and removal of the
residual acid-binding agents and other substances by washing, an
aramid polycondensate was obtained upon drying.
[0050] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.07 dl/g, the yield
in the aramid condensation stage was 96.2%, and the recovery rate
of CO.sub.2 was higher than 90%.
Example 10
[0051] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
9.34 g of the acid-binding agent triethylamine. The original gas
was replaced with nitrogen, and liquid carbon dioxide was added.
The reactor was kept at a temperature of 35.degree. C., and a
pressure of 8 MPa. Upon the substances in the pressure reactor were
dissolved, a p-phenylenediamine-triethylamine-supercritical carbon
dioxide mixture liquid was prepared. To another pressure reactor
equipped with a stirrer and connected to a dry nitrogen tube was
added 9.02 g of p-benzenedicarbonyl dichloride. The original gas
was replaced with nitrogen, and liquid carbon dioxide was added.
The reactor was kept at a temperature of 35.degree. C., and a
pressure of 8 MPa. Upon the substance in the pressure reactor was
dissolved, a solution of p-benzenedicarbonyl dichloride in
supercritical carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in supercritical carbon dioxide was
added to the p-phenylenediamine-triethylamine-supercritical carbon
dioxide mixture liquid while rapid stirring. The carbon dioxide was
maintained in a supercritical state throughout the reaction. The
stirring was continued until the reaction was completed. Water was
added to the pressure reactor. The CO.sub.2 gas was gradually
discharged, and compressed and condensed again for recovery. After
centrifugation, filtration, and removal of the residual
acid-binding agent and other substances by washing, an aramid
polycondensate was obtained upon drying.
[0052] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.3 dl/g, the yield in
the aramid condensation stage was 97.4%, and the recovery rate of
CO.sub.2 was higher than 90%.
Example 11
[0053] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
3.45 g of the acid-binding agent calcium hydroxide. The original
gas was replaced with nitrogen, and liquid carbon dioxide was
added. The reactor was kept at a temperature of 60.degree. C., and
a pressure of 20 MPa. Upon the substances in the pressure reactor
were dissolved, a p-phenylenediamine-calcium
hydroxide-supercritical carbon dioxide mixture liquid was prepared.
To another pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube was added 9.02 g of p-benzenedicarbonyl
dichloride. The original gas was replaced with nitrogen, and liquid
carbon dioxide was added. The reactor was kept at a temperature of
60.degree. C., and a pressure of 20 MPa. Upon the substance in the
pressure reactor was dissolved, a solution of p-benzenedicarbonyl
dichloride in supercritical carbon dioxide was prepared. The
solution of p-benzenedicarbonyl dichloride in supercritical carbon
dioxide was added to the p-phenylenediamine-calcium
hydroxide-supercritical carbon dioxide mixture liquid while rapid
stirring. The carbon dioxide was maintained in a supercritical
state throughout the reaction. The stirring was continued until the
reaction was completed. Water was added to the pressure reactor.
The CO.sub.2 gas was gradually discharged, and compressed and
condensed again for recovery. After centrifugation, filtration, and
removal of the residual acid-binding agent and other substances by
washing, an aramid polycondensate was obtained upon drying.
[0054] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.1 dl/g, the yield in
the aramid condensation stage was 96.7%, and the recovery rate of
CO.sub.2 was higher than 90%.
Example 12
[0055] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
2.69 g of triethylamine and 2.37 g of calcium hydroxide as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was added. The reactor was kept at a
temperature of 35.degree. C., and a pressure of 8 MPa. Upon the
substances in the pressure reactor were dissolved, a
p-phenylenediamine-triethylamine-calcium hydroxide-supercritical
carbon dioxide mixture liquid was prepared. To another pressure
reactor equipped with a stirrer and connected to a dry nitrogen
tube was added 9.02 g of p-benzenedicarbonyl dichloride. The
original gas was replaced with nitrogen, and liquid carbon dioxide
was added. The reactor was kept at a temperature of 35.degree. C.,
and a pressure of 8 MPa. Upon the substance in the pressure reactor
was dissolved, a solution of p-benzenedicarbonyl dichloride in
supercritical carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in supercritical carbon dioxide was
added to the p-phenylenediamine-triethylamine-calcium
hydroxide-supercritical carbon dioxide mixture liquid while rapid
stirring. The carbon dioxide was maintained in a supercritical
state throughout the reaction. The stirring was continued until the
reaction was completed. Water was added to the pressure reactor.
The CO.sub.2 gas was gradually discharged, and compressed and
condensed again for recovery. After centrifugation, filtration, and
removal of the residual acid-binding agents and other substances by
washing, an aramid polycondensate was obtained upon drying.
[0056] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.9 dl/g, the yield in
the aramid condensation stage was 98.4%, and the recovery rate of
CO.sub.2 was higher than 90%.
Example 13
[0057] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of m-phenylenediamine, and
3.15 g of trimethylamine and 1.57 g of lithium carbonate as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was added. The reactor was kept at a
temperature of 60.degree. C., and a pressure of 20 MPa. Upon the
substances in the pressure reactor were dissolved, a
p-phenylenediamine-trimethylamine-lithium carbonate-supercritical
carbon dioxide mixture liquid was prepared. To another pressure
reactor equipped with a stirrer and connected to a dry nitrogen
tube was added 9.02 g of m-benzenedicarbonyl dichloride. The
original gas was replaced with nitrogen, and liquid carbon dioxide
was added. The reactor was kept at a temperature of 60.degree. C.,
and a pressure of 20 MPa. Upon the substance in the pressure
reactor was dissolved, a solution of m-benzenedicarbonyl dichloride
in supercritical carbon dioxide was prepared. The solution of
m-benzenedicarbonyl dichloride in supercritical carbon dioxide was
added to the m-phenylenediamine-trimethylamine-lithium
carbonate-supercritical carbon dioxide mixture liquid while rapid
stirring. The carbon dioxide was maintained in a supercritical
state throughout the reaction. The stirring was continued until the
reaction was completed. Water was added to the pressure reactor.
The CO.sub.2 gas was gradually discharged, and compressed and
condensed again for recovery. After centrifugation, filtration, and
removal of the residual acid-binding agents and other substances by
washing, an aramid polycondensate was obtained upon drying.
[0058] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.86 dl/g, the yield
in the aramid condensation stage was 98.2%, and the recovery rate
of CO.sub.2 was higher than 90%.
Example 14
[0059] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
3.5 g of pyridine and 2.4 g of calcium carbonate as acid-binding
agents. The original gas was replaced with nitrogen, and liquid
carbon dioxide was added. The reactor was kept at a temperature of
100.degree. C., and a pressure of 10 MPa. Upon the substances in
the pressure reactor were dissolved, a
p-phenylenediamine-pyridine-calcium carbonate-supercritical carbon
dioxide mixture liquid was prepared. To another pressure reactor
equipped with a stirrer and connected to a dry nitrogen tube was
added 9.02 g of p-benzenedicarbonyl dichloride. The original gas
was replaced with nitrogen, and liquid carbon dioxide was added.
The reactor was kept at a temperature of 100.degree. C., and a
pressure of 10 MPa. Upon the substance in the pressure reactor was
dissolved, a solution of p-benzenedicarbonyl dichloride in
supercritical carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in supercritical carbon dioxide was
added to the p-phenylenediamine-pyridine-calcium
carbonate-supercritical carbon dioxide mixture liquid while rapid
stirring. The carbon dioxide was maintained in a supercritical
state throughout the reaction. The stirring was continued until the
reaction was completed. Water was added to the pressure reactor.
The CO.sub.2 gas was gradually discharged, and compressed and
condensed again for recovery. After centrifugation, filtration, and
removal of the residual acid-binding agents and other substances by
washing, an aramid polycondensate was obtained upon drying.
[0060] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 9 dl/g, the yield in
the aramid condensation stage was 98.7%, and the recovery rate of
CO.sub.2 was higher than 90%.
Example 15
[0061] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
2.69 g of triethylamine and 5.08 g of sodium bicarbonate as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was added. The reactor was kept at a
temperature of 50.degree. C., and a pressure of 8 MPa. Upon the
substances in the pressure reactor were dissolved, a
p-phenylenediamine-triethylamine-sodium bicarbonate-supercritical
carbon dioxide mixture liquid was prepared. To another pressure
reactor equipped with a stirrer and connected to a dry nitrogen
tube was added 9.02 g of p-benzenedicarbonyl dichloride. The
original gas was replaced with nitrogen, and liquid carbon dioxide
was added. The reactor was kept at a temperature of 50.degree. C.,
and a pressure of 8 MPa. Upon the substance in the pressure reactor
was dissolved, a solution of p-benzenedicarbonyl dichloride in
supercritical carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in supercritical carbon dioxide was
added to the p-phenylenediamine-triethylamine-sodium
bicarbonate-supercritical carbon dioxide mixture solution while
rapid stirring. The carbon dioxide was maintained in a
supercritical state throughout the reaction. The stirring was
continued until the reaction was completed. Water was added to the
pressure reactor. The CO.sub.2 gas was gradually discharged, and
compressed and condensed again for recovery. After centrifugation,
filtration, and removal of the residual acid-binding agents and
other substances by washing, an aramid polycondensate was obtained
upon drying.
[0062] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.58 dl/g, the yield
in the aramid condensation stage was 97.4%, and the recovery rate
of CO.sub.2 was higher than 90%.
Example 16
[0063] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
2.64 g of triethylamine and 2.32 g of calcium hydroxide as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was added. The reactor was kept at a
temperature of 35.degree. C., and a pressure of 8 MPa. Upon the
substances in the pressure reactor were dissolved, a
p-phenylenediamine-triethylamine-calcium hydroxide-supercritical
carbon dioxide mixture liquid was prepared. To another pressure
reactor equipped with a stirrer and connected to a dry nitrogen
tube was added 8.84 g of p-benzenedicarbonyl dichloride. The
original gas was replaced with nitrogen, and liquid carbon dioxide
was added. The reactor was kept at a temperature of 35.degree. C.,
and a pressure of 8 MPa. Upon the substance in the pressure reactor
was dissolved, a solution of p-benzenedicarbonyl dichloride in
supercritical carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in supercritical carbon dioxide was
added to the p-phenylenediamine-triethylamine-calcium
hydroxide-supercritical carbon dioxide mixture liquid while rapid
stirring. The carbon dioxide was maintained in a supercritical
state throughout the reaction. The stirring was continued until the
reaction was completed. Water was added to the pressure reactor.
The CO.sub.2 gas was gradually discharged, and compressed and
condensed again for recovery. After centrifugation, filtration, and
removal of the residual acid-binding agents and other substances by
washing, an aramid polycondensate was obtained upon drying.
[0064] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.08 dl/g, the yield
in the aramid condensation stage was 96.4%, and the recovery rate
of CO.sub.2 was higher than 90%.
Example 17
[0065] To a pressure reactor equipped with a stirrer and connected
to a dry nitrogen tube were added 4.80 g of p-phenylenediamine, and
3.15 g of trimethylamine and 1.58 g of lithium carbonate as
acid-binding agents. The original gas was replaced with nitrogen,
and liquid carbon dioxide was added. The reactor was kept at a
temperature of 60.degree. C., and a pressure of 20 MPa. Upon the
substances in the pressure reactor were dissolved, a
p-phenylenediamine-trimethylamine-lithium carbonate-supercritical
carbon dioxide mixture liquid was prepared. To another pressure
reactor equipped with a stirrer and connected to a dry nitrogen
tube was added 9.29 g of p-benzenedicarbonyl dichloride. The
original gas was replaced with nitrogen, and liquid carbon dioxide
was added. The reactor was kept at a temperature of 60.degree. C.,
and a pressure of 20 MPa. Upon the substance in the pressure
reactor was dissolved, a solution of p-benzenedicarbonyl dichloride
in supercritical carbon dioxide was prepared. The solution of
p-benzenedicarbonyl dichloride in supercritical carbon dioxide was
added to the p-phenylenediamine-trimethylamine-lithium
carbonate-supercritical carbon dioxide mixture liquid while rapid
stirring. The carbon dioxide was maintained in a supercritical
state throughout the reaction. The stirring was continued until the
reaction was completed. Water was added to the pressure reactor.
The CO.sub.2 gas was gradually discharged, and compressed and
condensed again for recovery. After centrifugation, filtration, and
removal of the residual acid-binding agents and other substances by
washing, an aramid polycondensate was obtained upon drying.
[0066] The resultant dried polymer was measured. The intrinsic
viscosity .eta.inh of the polycondensate was 8.1 dl/g, the yield in
the aramid condensation stage was 96%, and the recovery rate of
CO.sub.2 was higher than 90%.
[0067] The method for aramid polymerization using carbon dioxide as
a solvent according to the present invention has been described
with reference to the preferred embodiments. It is obvious to those
skilled in the art that the method described herein can be
appropriately modified, changed, or combined to implement the
techniques of the present invention without departing from the
content, spirit, and scope of the present invention. It should be
noted that all such substitutions and modifications are apparent to
those skilled in the art and are considered to be included in the
spirit, scope and content of the present invention.
* * * * *