[1] [Cross-Reference to Related Application]
[2] This application claims priority to Korean Patent
10 Application No. 10-2018-0164872, filed on December 19,
2018 in the Korean Intellectual Property Office, the
disclosure of which is incorporated herein by reference.
[3]
[4] The present invention relates to a method of
15 preparing an aromatic vinyl compound-vinyl cyanide
compound polymer and an apparatus for preparing the same.
More specifically, the present invention relates to a
method of preparing an aromatic vinyl compound-vinyl
cyanide compound polymer including a step of polymerizing
20 a reaction mixture containing an aromatic vinyl compound,
2
a vinyl cyanide compound, and an organic solvent in a
reactor and a step of transferring the vaporized reaction
mixture present in the upper space of the reactor to a
heat exchanger via a pipe and condensing the vaporized
5 reaction mixture, and an apparatus for preparing the
aromatic vinyl compound-vinyl cyanide compound polymer.
According to the present invention, the condensed reaction
mixture is transferred to one side of the pipe and sprayed
into the pipe to reduce the flow velocity of the reaction
10 mixture vaporized in the reactor and lower temperature.
Accordingly, a phenomenon (i.e., a polymer entrainment
phenomenon) wherein polymer particles in a reactor are
sucked into a heat exchanger is prevented, and occurrence
of polymerization in the heat exchanger is suppressed,
15 thereby preventing contamination of the heat exchanger and
prolonging a reaction operation cycle. Therefore,
productivity and quality may be improved.
20 【Background Art】
3
[5] In general, aromatic vinyl compound-vinyl cyanide
compound polymers (hereinafter referred to as "SAN resins")
have excellent moldability, rigidity, and electrical
properties. Because of these advantages, SAN resins are
5 widely used in various industrial fields including OA
equipment such as computers, printers, and copiers,
household appliances such as televisions and audio systems,
electrical and electronic parts, miscellaneous goods, and
the like. In particular, heat-resistant aromatic vinyl
10 compound-vinyl cyanide compound polymers that can withstand
high external temperatures are used for housings for
household appliances and interior materials for automobiles.
[6]
[7] An aromatic vinyl compound-vinyl cyanide compound
15 polymer is obtained by polymerizing an aromatic vinyl
compound and a vinyl cyanide compound in an organic solvent.
In this case, since the polymerization reaction is
exothermic, the temperature inside a reactor is increased by
heat of reaction during polymerization, and as a result, the
20 aromatic vinyl compound, the vinyl cyanide compound, and the
4
organic solvent are vaporized and are present in the upper
space of the reactor. In this case, heat control technology
may be applied. According to this technology, a heat
exchanger is installed at the upper surface of the reactor
5 to condense the aromatic vinyl compound, the vinyl cyanide
compound, and the organic solvent vaporized during
polymerization and to transfer the condensed aromatic vinyl
compound, vinyl cyanide compound, and organic solvent back
to the reactor. When the vaporized aromatic vinyl compound,
10 vinyl cyanide compound, and organic solvent are transferred
from the reactor to the heat exchanger via a pipe, the flow
velocity of the gas in the pipe is dramatically increased.
As a result, a phenomenon (i.e., a polymer entrainment
phenomenon) wherein the polymer polymerized in the reactor
15 is sucked into the heat exchanger together with the gas
occurs. The polymer introduced into the heat exchanger is
adhered to the inside thereof, and over time, the polymer is
allowed to grow into a polymer gel. Then, the polymer gel
is separated from the heat exchanger and flows into the
20 reactor. The gel introduced into the reactor and the
5
polymer present in the reactor adhere to each other, which
causes degradation in the quality of a SAN resin. In
addition, the aromatic vinyl compound, vinyl cyanide
compound, and organic solvent transferred to the heat
5 exchanger are polymerized due to the high temperature inside
the heat exchanger, and the resulting polymer adheres to the
heat exchanger. In this case, the reaction must be
temporarily stopped to remove the adhered polymer. This may
reduce productivity.
10 [8] Therefore, to improve the quality and productivity
of SAN resins, there is a need for a method of preventing
contamination of a heat exchanger by suppressing a
phenomenon wherein a polymer flows into the heat exchanger.
[9]
15 [10] [Related Art Document]
[11] [Patent Document]
[12] KR 1995-0008719 B1
【Disclosure】
20 【Technical Problem】
6
[13] Therefore, the present invention has been made in
view of the above problems, and it is one object of the
present invention to provide a method of preparing an
aromatic vinyl compound-vinyl cyanide compound polymer and
5 an apparatus for preparing the same. The method according
to the present invention includes a step of polymerizing a
reaction mixture containing an aromatic vinyl compound, a
vinyl cyanide compound, and an organic solvent in a reactor
and a step of transferring the vaporized reaction mixture
10 present in the upper space of the reactor to a heat
exchanger via a pipe and condensing the vaporized reaction
mixture. In the method, to prevent a phenomenon (i.e., a
polymer entrainment phenomenon) wherein polymer particles in
the reactor are sucked into the heat exchanger, the
15 condensed reaction mixture is sprayed into the pipe to
reduce the flow velocity of a reaction mixture vaporized in
the reactor and to lower temperature. Through this process,
the quality of the aromatic vinyl compound-vinyl cyanide
compound polymer may be improved. In addition, in the
20 method of the present invention, polymerization of the
7
vaporized reaction mixture in the heat exchanger may be
suppressed to prevent contamination of the heat exchanger
and to prolong a reaction operation cycle. As a result,
productivity may be increased.
5 [14] The above and other objects can be accomplished by
the present disclosure described below.
【Technical Solution】
[15] In accordance with one aspect of the present
10 invention, provided is a method of preparing an aromatic
vinyl compound-vinyl cyanide compound polymer including
polymerizing a reaction mixture containing an aromatic vinyl
compound, a vinyl cyanide compound, and an organic solvent
in a reactor; and transferring the vaporized reaction
15 mixture present in the upper space of the reactor to a heat
exchanger via a pipe and condensing the vaporized reaction
mixture, wherein the condensed reaction mixture is
transferred to one side of the pipe and sprayed into the
pipe.
20 [16]
8
[17] In accordance with another aspect of the present
invention, provided is an apparatus for preparing an
aromatic vinyl compound-vinyl cyanide compound polymer
including a reactor in which a reaction mixture containing
5 an aromatic vinyl compound, a vinyl cyanide compound, and an
organic solvent is polymerized; a heat exchanger for
condensing the reaction mixture vaporized in the reactor; a
gas pipe for transferring the vaporized reaction mixture
from the upper space of the reactor to the heat exchanger;
10 and a condensate pipe for transferring the condensed
reaction mixture from the heat exchanger to one side of the
gas pipe, wherein the condensate pipe includes a spray
nozzle.
15 【Advantageous effects】
[18] According to the present invention, when a reaction
mixture containing an aromatic vinyl compound, a vinyl
cyanide compound, and an organic solvent is polymerized in a
reactor, the flow velocity of the reaction mixture vaporized
20 in the reactor can be reduced and temperature can be lowered
9
to prevent a phenomenon (i.e., a polymer entrainment
phenomenon) wherein polymer particles in the reactor are
sucked into a heat exchanger and to suppress polymerization
of the vaporized reaction mixture in the heat exchanger. As
5 a result, contamination of the heat exchanger can be
prevented and a reaction operation cycle can be extended.
Therefore, the method of the present invention can increase
productivity and quality of the aromatic vinyl compoundvinyl cyanide compound polymer.
10
【Description of Drawings】
[19] FIG. 1 is a schematic drawing for explaining the
method according to the present invention including a step
of polymerizing a reaction mixture containing an aromatic
15 vinyl compound, a vinyl cyanide compound, and an organic
solvent in a reactor and a step of transferring the
vaporized reaction mixture present in the upper space of the
reactor to a heat exchanger via a pipe and condensing the
vaporized reaction mixture in the heat exchanger, wherein
20 the condensed reaction mixture is sprayed into the pipe from
10
one side of the pipe.
[20]
[21] FIG. 2 is a schematic drawing for explaining a
conventional method including a step of polymerizing a
5 reaction mixture containing an aromatic vinyl compound, a
vinyl cyanide compound, and an organic solvent in a reactor
and a step of transferring the vaporized reaction mixture
present in the upper space of the reactor to a heat
exchanger via a pipe and condensing the vaporized reaction
10 mixture in the heat exchanger, wherein the condensed
reaction mixture is introduced into the reactor.
【Best mode】
[22] Hereinafter, the method of preparing an aromatic
15 vinyl compound-vinyl cyanide compound polymer according to
the present invention will be described in detail.
[23] In general, when an aromatic vinyl compound-vinyl
cyanide compound polymer is prepared, a vaporized reaction
mixture containing an aromatic vinyl compound, a vinyl
20 cyanide compound, and an organic solvent present in the
11
upper space of a reactor is polymerized in a heat exchanger,
and as a result, the inside of the heat exchanger is
contaminated with the polymerized products. Furthermore, in
addition to the vaporized reaction mixture, a polymer
5 generated in the reactor is sucked into the heat exchanger,
and then the polymer is re-introduced into the reactor,
thereby degrading the quality of a final product. To solve
these problems, the present inventors have made a ceaseless
effort. As a result, the present inventors developed a
10 method of preparing an aromatic vinyl compound-vinyl cyanide
compound polymer and an apparatus for preparing the same.
According to the method and apparatus of the present
invention, by spraying a reaction mixture condensed in a
heat exchanger from one side of a pipe into the pipe, the
15 flow velocity of a reaction mixture vaporized in a reactor
is reduced and temperature is lowered, thereby preventing a
phenomenon wherein a polymer is sucked into the heat
exchanger. The present inventors confirmed that, when the
method and apparatus of the present invention are used, the
20 quality of a polymer is improved and a reaction operation
12
cycle is extended to increase productivity. Based on these
results, the present inventors have further intensively
studied and completed the present invention.
[24]
5 [25] The method of preparing an aromatic vinyl compoundvinyl cyanide compound polymer according to the present
invention will be described in detail as follows.
[26]
[27] The method of preparing an aromatic vinyl compound10 vinyl cyanide compound polymer according to the present
invention includes a step of polymerizing a reaction mixture
containing an aromatic vinyl compound, a vinyl cyanide
compound, and an organic solvent in a reactor and a step of
transferring the vaporized reaction mixture present in the
15 upper space of the reactor to a heat exchanger via a pipe
and condensing the vaporized reaction mixture. In the
method of the present invention, the condensed reaction
mixture is transferred to one side of the pipe and sprayed
into the pipe. Through this process, the flow velocity of
20 the reaction mixture vaporized in the reactor is reduced and
13
temperature is lowered, thereby suppressing occurrence of
polymerization inside the heat exchanger and preventing
contamination of the heat exchanger. As a result, the
productivity of the aromatic vinyl compound-vinyl cyanide
5 compound polymer may be increased. In addition, a
phenomenon wherein a polymer present in the reactor is
sucked into the heat exchanger is prevented, thereby
improving the quality of a final product.
[28]
10 [29] Polymerization step
[30] In the polymerization step, a reaction mixture
containing an aromatic vinyl compound, a vinyl cyanide
compound, and an organic solvent is polymerized in a reactor.
[31]
15 [32] For example, the aromatic vinyl compound may be one
or more selected from the group consisting of styrene, αmethyl styrene, p-methyl styrene, p-bromostyrene, pchlorostyrene, and o-bromostyrene.
[33] For example, the vinyl cyanide compound may be
20 acrylonitrile, methacrylonitrile, or a mixture thereof.
14
[34] For example, the organic solvent may be one or more
selected from the group consisting of toluene, ethylbenzene,
xylene, methyl ethyl ketone, and methyl isobutyl ketone.
[35]
5 [36] For example, the reaction mixture may contain 40 to
80 % by weight of the aromatic vinyl compound, 10 to 35 % by
weight of the vinyl cyanide compound, and 5 to 35 % by
weight of the organic solvent, preferably 50 to 75 % by
weight of the aromatic vinyl compound, 15 to 30 % by weight
10 of the vinyl cyanide compound, and 10 to 25 % by weight of
the organic solvent. Within this range, mechanical
properties such as tensile strength and impact strength,
heat resistance, and thermal stability may be improved.
[37]
15 [38] For example, based on 100 parts by weight in total
of the aromatic vinyl compound and the vinyl cyanide
compound, 0.1 to 10 parts by weight, preferably 0.1 to 5
parts by weight of an initiator, a molecular weight modifier,
or a mixture thereof is added to the reaction mixture to
20 perform polymerization.
15
[39]
[40] For example, the initiator may be one or more
selected from the group consisting of t-butyl hydroperoxide,
cumene hydroperoxide, diisopropylbenzene hydroperoxide, t5 hexyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide,
dicumyl peroxide, and t-butyl cumyl peroxide.
[41]
[42] For example, the molecular weight modifier may be
one or more selected from the group consisting of n-dodecyl
10 mercaptan, tertiary dodecyl mercaptan, n-tetradecyl
mercaptan, and tertiary tetradecyl mercaptan.
[43]
[44] For example, the polymerization reaction may be
performed at a temperature of 140 to 170 °C under a pressure
15 of 1.0 to 4.0 kgf/cm2g, preferably at a temperature of 150
to 165 °C under a pressure of 1.5 to 3.5 kgf/cm2g. Within
this range, the polymerization conversion rate may be
excellent.
[45]
20 [46] Other additives not specifically mentioned in the
16
present description can be appropriately selected as needed.
There is no particular limitation as long as the additives
are generally used to prepare aromatic vinyl compound-vinyl
cyanide compound polymers.
5 [47]
[48] When the aromatic vinyl compound and the vinyl
cyanide compound polymer are polymerized, other reaction
conditions other than the above-described conditions, such
as reaction time, reaction temperature, pressure, and time
10 points of introduction of reactants, are not particularly
limited insofar as the reaction conditions are within a
range that is commonly used in the art to which the present
invention pertains, and can be appropriately selected and
carried out as necessary.
15 [49]
[50] Condensation step
[51] In the condensation step, a vaporized reaction
mixture present in the upper space of a reactor is
transferred to a heat exchanger via a pipe and condensed in
20 the heat exchanger. Then, the condensed reaction mixture is
17
sprayed into the pipe from one side of the pipe.
[52]
[53] For example, the spraying may be performed so that
the flow of the condensed reaction mixture is countercurrent
5 to the flow of the vaporized reaction mixture. In this case,
the flow velocity of the reaction mixture vaporized in the
reactor may be reduced, and temperature may be lowered. By
reducing the flow velocity of the vaporized reaction mixture,
a phenomenon wherein a polymer is sucked into the heat
10 exchanger together with the reaction mixture vaporized in
the reactor may be prevented. As a result, the quality of
an aromatic vinyl compound-vinyl cyanide compound polymer
may be improved. When a polymer present in the reactor is
sucked into the heat exchanger together with the vaporized
15 reaction mixture, the polymer introduced into the heat
exchanger is allowed to grow into a polymer gel, and the
polymer gel flows into the reactor. The polymer gel
introduced into the reactor and a polymer present in the
reactor adhere to each other, which causes degradation in
20 the quality of a final product. In addition, by lowering
18
the temperature of the vaporized reaction mixture,
polymerization of the reaction mixture in the heat exchanger
may be suppressed, thereby preventing contamination of the
heat exchanger. As a result, a reaction operation cycle may
5 be extended to increase the productivity of a final product.
[54]
[55] For example, the temperature of the reaction
mixture transferred to the heat exchanger after spraying may
be 100 to 140 °C, preferably 110 to 130 °C, and the
10 temperature of the reaction mixture discharged from the heat
exchanger may be 15 to 50 °C, preferably 20 to 45 °C.
Within this range, the vaporized reaction mixture may be
prevented from being polymerized in the heat exchanger,
thereby preventing contamination of the heat exchanger. As
15 a result, a reaction operation cycle may be extended to
increase the productivity of a final product.
[56]
[57] For example, the flow velocity of the reaction
mixture transferred to the heat exchanger after spraying may
20 be 1.0 to 2.0 m/sec, preferably 1.2 to 1.7 m/sec, more
19
preferably 1.2 to 1.4 m/sec. Within this range, a
phenomenon wherein a polymer present in the reactor is
sucked into the heat exchanger may be prevented, thereby
improving the quality of an aromatic vinyl compound-vinyl
5 cyanide compound polymer.
[58]
[59] In the present description, the flow velocity can
be calculated by Equation 1 below.
[60] [Equation 1]
10 [61] Flow velocity (m/sec) = Gas volumetric flow rate /
Cross-sectional area of pipe
[62]
[63] For example, the spray may include all or a portion,
preferably all, of the reaction mixture transferred to the
15 heat exchanger. In this case, the flow of the vaporized
reaction mixture is countercurrent to the flow of the
condensed reaction mixture, such that the temperature and
flow velocity of the vaporized reaction mixture are reduced.
Consequently, a phenomenon wherein a polymer present in the
20 reactor is sucked into the heat exchanger may be suppressed,
20
and the vaporized reaction mixture may be prevented from
being polymerized in the heat exchanger.
[64]
[65] In the present description, countercurrent refers
5 to a case wherein, when there is heat or material transfer
between two fluids, the fluids flow in opposite directions.
[66]
[67] In the present description, the flow rate may be
measured using a flowmeter provided in a condensate pipe for
10 spraying the reaction mixture condensed in the heat
exchanger.
[68]
[69] In the present description, the heat exchanger is
not particularly limited as long as it is a heat exchanger
15 commonly used in the art to which the present invention
pertains. For example, a horizontal shell and tube heat
exchanger or a vertical shell and tube heat exchanger may be
used as the heat exchanger of the present invention.
[70]
20 [71] The apparatus for preparing an aromatic vinyl
21
compound-vinyl cyanide compound polymer according to the
present invention includes a reactor in which a reaction
mixture containing an aromatic vinyl compound, a vinyl
cyanide compound, and an organic solvent is polymerized; a
5 heat exchanger for condensing the reaction mixture vaporized
in the reactor; a gas pipe for transferring the vaporized
reaction mixture from the upper space of the reactor to the
heat exchanger; and a condensate pipe for transferring the
condensed reaction mixture from the heat exchanger to one
10 side of the gas pipe. As a feature of this apparatus, the
condensate pipe includes a spray nozzle. According to the
apparatus, the flow velocity of the reaction mixture
vaporized in the reactor may be reduced, and temperature may
be lowered. As a result, the vaporized reaction mixture may
15 be prevented from being polymerized in the heat exchanger,
thereby preventing contamination of the heat exchanger and
increasing productivity. In addition, a phenomenon wherein
a polymer present in the reactor is sucked into the heat
exchanger may be prevented, thereby improving the quality of
20 a final product.
22
[72]
[73] For example, the spray nozzle is installed so that
a part or the whole thereof is located in the gas pipe and
the flow of the condensed reaction mixture to be sprayed is
5 countercurrent to the flow of the reaction mixture vaporized
in the reactor. In this case, the flow velocity of the
reaction mixture vaporized in the reactor may be reduced,
and temperature may be lowered. As a result, a phenomenon
(i.e., an entrainment phenomenon) wherein a polymer
10 generated in the reactor is sucked into the heat exchanger
may be prevented, thereby improving the productivity and
quality of a final product.
[74]
[75] The nozzle of the present invention is not
15 particularly limited as long as it is a nozzle commonly used
in the art to which the present invention pertains.
[76]
[77] The descriptions of the reactor, the heat exchanger,
and the reaction mixture included in the apparatus for
20 preparing an aromatic vinyl compound-vinyl cyanide compound
23
polymer are the same as those described above, and thus are
omitted.
[78]
[79] The method of preparing an aromatic vinyl compound5 vinyl cyanide compound polymer and the apparatus for
preparing the same according to the present invention are
described with reference to FIGS. 1 and 2. It should be
understood that these drawings are merely schematic
representations of the present invention and are not to be
10 construed as limited to the embodiments. Only means
necessary for explaining the present invention are
illustrated in the drawings for ease of understanding, and
other means necessary for carrying out the method and
apparatus are omitted from the drawings.
15 [80]
[81] In FIG. 1, a reactor, a heat exchanger, a gas pipe,
a condensate pipe, and a spray nozzle used in Examples 1 to
2 are schematically illustrated. Referring to FIG. 1, a
reaction mixture containing an aromatic vinyl compound, a
20 vinyl cyanide compound, and an organic solvent is
24
polymerized in a reactor, and the vaporized reaction mixture
present in the upper space of the reactor is transferred to
a heat exchanger via a gas pipe and condensed in the heat
exchanger. The condensed reaction mixture is transferred to
5 the gas pipe via a condensate pipe, and then is sprayed
through a spray nozzle installed in the gas pipe. At this
time, the flow of the sprayed condensed reaction mixture is
countercurrent to the flow of the vaporized reaction mixture,
and the sprayed condensed reaction mixture is re-introduced
10 into the reactor.
[82]
[83] In addition, in FIG. 2, a reactor, a heat exchanger,
a gas pipe, and a condensate pipe used in Comparative
Example 1are schematically illustrated. Referring to FIG. 2,
15 a reaction mixture containing an aromatic vinyl compound, a
vinyl cyanide compound, and an organic solvent is
polymerized in a reactor, and the vaporized reaction mixture
present in the upper space of the reactor is transferred to
a heat exchanger via a gas pipe and condensed in the heat
20 exchanger. The condensed reaction mixture is re-introduced
25
into the upper space of the reactor via a condensate pipe.
[84]
[85] Hereinafter, the present invention will be
described in more detail with reference to the following
5 preferred examples. However, these examples are provided
for illustrative purposes only and should not be construed
as limiting the scope and spirit of the present invention.
In addition, it will be apparent to those skilled in the art
that various changes and modifications may be made without
10 departing from the spirit and scope of the present invention,
and such changes and modifications are also within the scope
of the appended claims.
[86]
[87] [Examples]
15 [88] The conditions for each step are shown in Table 1
below.
[89]
[90] Example 1
[91] < Polymerization step >
20 [92] A reaction mixture containing 60 % by weight of
26
styrene, 25 % by weight of acrylonitrile, and 15 % by weight
of toluene was introduced into a reactor at a flow rate of
20,000 kg/hr, and polymerization was performed at a
temperature of 160 °C under a pressure of 1.5 kgf/cm2g.
5 [93]
[94] < Condensation step >
[95] The vaporized reaction mixture containing styrene,
acrylonitrile, and toluene present in the upper space of the
reactor was transferred to a heat exchanger via a gas pipe
10 and condensed in the heat exchanger. In this case, the
temperature of a refrigerant contained in the heat exchanger
was set to 35 to 37 °C. The condensed reaction mixture was
transferred to the gas pipe via a condensation pipe. Then,
all of the reaction mixture transferred to the heat
15 exchanger, e.g., at a flow rate of 1270 kg/hr, was sprayed
to the vaporized reaction mixture through a spray nozzle
located at the condensation pipe, so that the flow of the
sprayed reaction mixture is countercurrent to the flow of
the vaporized reaction mixture. In this case, the flow rate
20 of the reaction mixture vaporized in the reactor was
27
measured using a flowmeter in the condensate pipe through
which the condensed reaction mixture is transferred. In
addition, the flow velocity of the reaction mixture
transferred to the heat exchanger after spraying was
5 measured by Equation 1. In this case, the flow rate
measured in the condensate pipe was substituted into
Equation 1.
[96] [Equation 1]
[97] Flow velocity (m/sec) = Gas volumetric flow rate /
10 Cross-sectional area of pipe
[98]
[99] In addition, the temperature of the reaction
mixture transferred to the heat exchanger after spraying and
the temperature of the reaction mixture condensed in the
15 heat exchanger and discharged from the heat exchanger were
measured using a thermometer.
[100] In addition, a prepared SAN polymer was placed in a
single-screw extruder, and extrusion was performed at 250 °C
and 50 rpm to obtain a sheet-type film. Through this
20 process, the quality of the SAN polymer was evaluated.
28
[101]
[102] Example 2
[103] Example 2 was performed in the same manner as in
Example 1, except that the temperature of a refrigerant
5 contained in a heat exchanger was set to 20 to 22 °C in a
condensation step, and all of the reaction mixture
transferred to the heat exchanger, e.g., at a flow rate of
1210 kg/hr, was sprayed.
[104]
10 [105] Comparative Example 1
[106] < Polymerization step >
[107] A reaction mixture containing 60 % by weight of
styrene, 25 % by weight of acrylonitrile, and 15 % by weight
of toluene was introduced into a reactor at a flow rate of
15 20,000 kg/hr, and polymerization was performed at a
temperature of 160 °C under a pressure of 1.5 kgf/cm2g.
[108]
[109] < Condensation step >
[110] The vaporized reaction mixture containing styrene,
20 acrylonitrile, and toluene present in the upper space of the
29
reactor was transferred to a heat exchanger via a gas pipe
and condensed in the heat exchanger. In this case, the
temperature of a refrigerant contained in the heat exchanger
was set to 30 °C. The condensed reaction mixture was re5 introduced into the reactor via a condensation pipe.
[111] In this case, the flow rate of the reaction mixture
vaporized in the reactor was measured using a flowmeter in
the condensate pipe through which the condensed reaction
mixture is transferred to the heat exchanger. In addition,
10 the flow velocity of the gaseous reaction mixture
transferred to the heat exchanger was estimated using the
flow rate and Equation 1. The temperature of the reaction
mixture transferred to the heat exchanger and the
temperature of the reaction mixture condensed in the heat
15 exchanger and discharged from the heat exchanger were
measured using a thermometer.
[112] In addition, a prepared SAN polymer was placed in a
single-screw extruder, and extrusion was performed at 250 °C
and 50 rpm to obtain a sheet-type film. Through this
20 process, the quality of the SAN polymer was evaluated.
30
[113]
[114] [Test Example]
[115] The properties of specimens prepared according to
Examples 1 and 2 and Comparative Example 1 were evaluated
5 using the following method, and the obtained results are
shown in Table 1 below.
[116]
[117] Measurement method
[118] * Quality of SAN polymers: SAN polymer films
10 prepared using a single-screw extruder were cut to 10 cm ×
10 cm, and the number of polymer gels observed on the
surfaces of the SAN polymer films were counted with the
naked eye. Depending on the number of polymer gels, the
quality of SAN polymer was evaluated as follows. 0 to 5
15 polymer gels: excellent, 6 to 10 polymer gels: normal, and
more than 10 polymer gels: poor.
[119]
[120] 【Table 1】
Classification Example 1 Example 2 Comparative
Example 1
Flow rate of reaction mixture
transferred to heat exchanger
(kg/hr)
1270 1210 2098
Flow velocity of reaction 1.31 1.26 2.27
31
mixture transferred to heat
exchanger after spraying
(m/sec)
Temperature of reaction
mixture transferred to heat
exchanger after spraying (°C)
123 123 160
Flow rate of spray (kg/hr) 1270 1210 0
Temperature of reaction
mixture discharged from heat
exchanger (°C)
40 25 74
Quality of SAN polymer Excellent Excellent Normal
[121] As shown in Table 1, in Examples 1 and 2 according
to the present invention, a reaction mixture condensed in a
heat exchanger is transferred to one side of a pipe and
sprayed into the pipe. At this time, the flow of the
5 sprayed reaction mixture is countercurrent to the flow of a
vaporized reaction mixture present in the upper space of a
reactor. In this case, the temperature and flow velocity of
the reaction mixture transferred to the heat exchanger after
spraying are reduced. Accordingly, polymerization of the
10 reaction mixture in the heat exchanger may be suppressed,
thereby extending a reaction operation cycle and improving
the productivity. In addition, a phenomenon wherein a
polymer present in the reactor is sucked into the heat
exchanger may be suppressed, thereby improving the quality
15 of a styrene-acrylonitrile polymer.
[122] In Example 2, the temperature of a refrigerant used
32
in the heat exchanger is lower than that in Example 1, such
that the temperature of a reaction mixture condensed in the
heat exchanger is lower than that in Example 1. However,
since the flow rate of a reaction mixture transferred to the
5 heat exchanger is lower than that in Example 1, the
temperature of a reaction mixture transferred to the heat
exchanger after spraying is the same as in Example 1.
[123] On the other hand, in the case of Comparative
Example 1 in which a reaction mixture condensed in a heat
10 exchanger is re-introduced into a reactor, compared to
Examples 1 and 2, the flow rate and temperature of a
vaporized reaction mixture present in the upper space of the
reactor are very high. As a result, a phenomenon wherein a
polymer present in the reactor is sucked into the heat
15 exchanger occurs. In addition, a vaporized high temperature
reaction mixture is polymerized in the heat exchanger, and
the polymerized product adheres to the inside of the heat
exchanger, shortening a reaction operation cycle and
reducing the productivity. In addition, a polymer present
20 in the reactor is sucked into the heat exchanger, and the
33
introduced polymer is allowed to grow into a polymer gel.
The polymer gel is re-introduced into the reactor, resulting
in degradation in the quality of the styrene-acrylonitrile
polymer.

WE CLAIM

【Claim 1】
A method of preparing an aromatic vinyl compound-vinyl
5 cyanide compound polymer, comprising:
polymerizing a reaction mixture containing an aromatic
vinyl compound, a vinyl cyanide compound, and an organic
solvent in a reactor; and
transferring the vaporized reaction mixture present in
10 an upper space of the reactor to a heat exchanger via a pipe
and condensing the vaporized reaction mixture,
wherein the condensed reaction mixture is transferred
to one side of the pipe and sprayed into the pipe.
15 【Claim 2】
The method according to claim 1, wherein the spraying
is performed so that a flow of the condensed reaction
mixture is countercurrent to a flow of the vaporized
reaction mixture.
20
35
【Claim 3】
The method according to claim 1, wherein the reaction
mixture contains 40 to 80 % by weight of the aromatic vinyl
compound, 10 to 35 % by weight of the vinyl cyanide
5 compound, and 5 to 35 % by weight of the organic solvent.
【Claim 4】
The method according to claim 1, wherein the spray
comprises all or a portion of the reaction mixture
10 transferred to the heat exchanger.
【Claim 5】
The method according to claim 1, wherein a temperature
of the reaction mixture transferred to the heat exchanger
15 after the spraying is 100 to 140 °C, and a temperature of
the reaction mixture discharged from the heat exchanger is
15 to 50 °C.
【Claim 6】
20 The method according to claim 1, wherein a flow
36
velocity of the reaction mixture transferred to the heat
exchanger after the spraying is 1.0 to 2.0 m/sec.
【Claim 7】
5 The method according to claim 1, wherein the
polymerization reaction is performed at a temperature of 150
to 170 °C under a pressure of 1.0 to 4.0 kgf/cm2g.
【Claim 8】
10 The method according to claim 1, wherein the aromatic
vinyl compound is one or more selected from the group
consisting of styrene, α-methyl styrene, p-methyl styrene,
p-bromostyrene, p-chlorostyrene, and o-bromostyrene.
15 【Claim 9】
The method according to claim 1, wherein the vinyl
cyanide compound is acrylonitrile, methacrylonitrile, or a
mixture thereof.
20 【Claim 10】
37
The method according to claim 1, wherein the organic
solvent is one or more selected from the group consisting of
toluene, ethylbenzene, xylene, methyl ethyl ketone, and
methyl isobutyl ketone.
5
【Claim 11】
An apparatus for preparing an aromatic vinyl compoundvinyl cyanide compound polymer, comprising:
a reactor in which a reaction mixture containing an
10 aromatic vinyl compound, a vinyl cyanide compound, and an
organic solvent is polymerized;
a heat exchanger for condensing the reaction mixture
vaporized in the reactor;
a gas pipe for transferring the vaporized reaction
15 mixture from an upper space of the reactor to the heat
exchanger; and
a condensate pipe for transferring the condensed
reaction mixture from the heat exchanger to one side of the
gas pipe,
20 wherein the condensate pipe comprises a spray nozzle.
38
【Claim 12】
The apparatus according to claim 11, wherein the spray
nozzle is installed so that a part or a whole thereof is
5 located in the gas pipe and a flow of a condensed reaction
mixture to be sprayed is countercurrent to a flow of a
reaction mixture vaporized in the reactor.