KR100843611B1 - Preparation method of copolymer of aromatic vinyl monomer and vinylcyano compound - Google Patents

Abstract

In the present invention, a first polymerization is carried out by continuously adding a mixed initiator of 70 to 90% by weight of a reaction mixture containing an aromatic vinyl monomer, a vinyl cyanide compound and a reaction solvent, a tetrafunctional group-containing initiator and a bifunctional group-containing initiator to the first reactor. After the first polymerized polymer is moved to the second reactor, the remaining amount of the total amount of the reaction mixture 10-30% by weight of the aromatic vinyl monomer and the vinyl cyanide compound, characterized in that the second polymerization by continuously introducing into the second reactor It provides a method for producing a copolymer.

The copolymer of the aromatic vinyl monomer and the vinyl cyanide compound produced by the method according to the present invention has a high molecular weight and excellent mechanical properties, and at the same time, a high conversion rate of the reaction, thereby improving reaction efficiency and thus improving productivity.

Tetrafunctional group containing initiator, bifunctional group containing initiator, aromatic vinyl monomer, vinyl cyanide compound

Description

Preparation method of copolymer of aromatic vinyl monomer and vinylcyano compound

The present invention relates to a method for preparing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound, and more particularly, to an aromatic vinyl monomer having a high molecular weight and a high conversion rate of the reaction, thereby improving the reaction efficiency and reducing the production cost. And a method for producing a copolymer of a vinyl cyanide compound.

Copolymers of aromatic vinyl monomers such as styrene and vinyl cyan compounds such as acrylonitrile are widely used in various industrial fields as molding materials having excellent transparency, chemical resistance and mechanical properties, and excellent hardness, tensile properties, molding shrinkage rate and impact resistance. have.

Copolymers of aromatic vinyl monomers and vinyl cyanide compounds may be prepared using various polymerization methods such as emulsion polymerization, bulk polymerization, and solution polymerization.However, in emulsion polymerization, impurities such as emulsifiers and flocculants remain in the polymer and are thermally stable. There is such a problem that it is poorly used industrially, and is usually produced by a bulk polymerization method or a solution polymerization method.

The copolymer of the aromatic vinyl monomer and the vinyl cyanide compound produced by the bulk polymerization method or the solution polymerization method needs to have a high molecular weight in order to have good mechanical properties such as tensile strength and impact strength, and heat resistance and thermal stability. In order to increase the efficiency of the reaction by minimizing the amount of unreacted monomer after the reaction, the conversion rate of the reaction should be high.

In order to increase the conversion rate of the reaction, an initiator is applied in preparing the copolymer, and the application of such an initiator generally tends to reduce the molecular weight. Therefore, various studies have been conducted to improve the conversion efficiency and molecular weight and to improve the reaction efficiency while at the same time improving the physical properties.

U.S. Patent No. 4,874,829 discloses a process for preparing copolymers or terpolymers by bulk polymerization using alphamethylstyrene, acrylonitrile and maleimide monomers. This method is effective in increasing the conversion rate in preparing a polymer containing alphamethylstyrene by including a large amount of acrylonitrile having high reactivity in order to overcome the low polymerization conversion rate of alphamethylstyrene. However, this method has a problem that since the content of acrylonitrile in the reaction mixture is very high, the resin prepared therefrom is not only severely discolored but also gel can be formed.

In addition, U. S. Patent No. 4,795, 780 discloses a method for preparing a copolymer containing alphamethylstyrene and acrylonitrile by continuous bulk polymerization. In order to overcome the low conversion rate when preparing a copolymer containing alphamethylstyrene, this method copolymerizes the monomer mixture by continuously introducing two stirred tank reactors into a reactor connected in series, in particular by evaporating and condensing in the second reactor. The method to overcome the low conversion rate by applying the condensate to the first reactor was proposed. However, this method is not effective in increasing the conversion rate and molecular weight of the monomer using azobisisobutyronitrile (AIBN) as an initiator, and there is a problem that the molecular weight distribution of the resulting polymer is too wide.

In addition, Korean Patent No. 10-0417066 discloses heat resistance by injecting a mixed initiator of a multifunctional initiator and a monofunctional initiator into a reaction mixture of alphamethylstyrene, acrylonitrile and a reaction solvent using a bulk polymerization or solution polymerization method. Disclosed is a method for producing a further thermoplastic resin. The method is a method using a mixed initiator to increase the heat resistance of the existing heat-resistant resin, but the effect of improving the heat resistance according to the molecular weight increase, but it is difficult to improve the conversion rate of the reaction by more than 70%, because it uses a mono-functional group-containing initiator, There is a problem that gels may form in the polymer.

Therefore, there is a need for a method for minimizing gel formation in a polymer while simultaneously increasing the molecular weight and conversion rate in preparing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound.

The present invention has been made in view of the above situation, and the technical problem to be achieved by the present invention is to provide a method for producing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound having a high molecular weight and a high conversion of the reaction.

The present invention to achieve the above technical problem

(a) 70 to 90% by weight of the total amount of the reaction mixture prepared by mixing the aromatic vinyl monomer, the vinyl cyanide compound, and the reaction solvent with a tetrafunctional initiator containing one hour half-life temperature of 100 to 125 ° C. and one hour half-life temperature of 130 to 130 ° C. Continuously injecting a mixed initiator prepared by mixing a bifunctional group-containing initiator having a temperature of 160 ° C. into a first reactor to carry out a first polymerization;

(b) continuously polymerizing the reaction product formed in the first reactor by continuously adding 10 to 30 wt% of the remaining amount of the reaction mixture into the second reactor while continuously moving the reaction product formed in the second reactor; And

(c) moving the reaction product formed in the second reactor to a recovery tank to recover an unreacted monomer and a reaction solvent and separating a polymer, thereby providing a method of preparing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound.

When the copolymer of the aromatic vinyl monomer and the vinyl cyanide compound is prepared according to the preparation method of the present invention, a tetrafunctional group-containing initiator having a half-life temperature of 100 to 125 ° C. for 1 hour increases the molecular weight when the reaction temperature of the initial reactor is relatively low. In addition, since the bifunctional group-containing initiator having a half-life temperature of 130 to 160 ° C. for 1 hour increases the molecular weight and increases the conversion rate when the reaction temperature of the late reaction reactor is relatively high, the molecular weight of the resulting polymer can be increased. The conversion of the reaction can be increased.

Hereinafter, the present invention will be described in detail.

In the present invention, a method for preparing a copolymer of the aromatic vinyl monomer and the vinyl cyanide compound

(a) 70 to 90% by weight of the total amount of the reaction mixture prepared by mixing the aromatic vinyl monomer, the vinyl cyanide compound, and the reaction solvent with a tetrafunctional initiator containing one hour half-life temperature of 100 to 125 ° C. and one hour half-life temperature of 130 to 130 ° C. Continuously injecting a mixed initiator prepared by mixing a bifunctional group-containing initiator at 160 ° C. into a first reactor (first polymerization step);

(b) while continuously moving the reaction product formed in the first reactor to the second reactor to 10 to 30% by weight additionally continuously added to the second reactor in the second reactor to the second polymerization (secondary polymerization step) ); And

(c) recovering the unreacted monomer and the reaction solvent by separating the reaction product formed in the second reactor into a recovery tank and separating the polymer (polymer separation step).

Hereinafter, it will be described divided by each step.

(a) primary polymerization stage

In this step, a portion of the total amount of the reaction mixture prepared by mixing the aromatic vinyl monomer, the vinyl cyanide compound and the reaction solvent and the mixed initiator are continuously added to the first reactor and polymerized under appropriate polymerization conditions to produce an aromatic vinyl having a predetermined conversion and molecular weight. Forming a copolymer of the monomer and the vinyl cyanide compound.

In the present invention, the aromatic vinyl monomer may be used without limitation vinyl compound containing an aromatic group, preferably at least one selected from the group consisting of styrene, α-methyl styrene and p-methyl styrene.

In addition, the vinyl cyanated compound in the present invention may be used without limitation vinyl compound containing a cyan group, preferably at least one selected from the group consisting of acrylonitrile, methacrylonitrile and ethacrylonitrile Can be.

In addition, in the present invention, the reaction solvent is compatible with the aromatic vinyl monomer and the vinyl cyanide compound, but a material used as a conventional reaction solvent in the field of the present invention may be used without limitation, preferably toluene, tetra At least one selected from the group consisting of hydrofuran, ethyl benzene, benzene, cyclohexanone and dimethylformamide can be used.

In preparing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound by the preparation method according to the present invention, in order to minimize gel formation, a reaction mixture having an appropriate reactant content ratio is used in order to minimize the formation of a gel. Preferably, in the present invention, it is preferable to use a reaction mixture containing 50 to 90% by weight of the aromatic vinyl monomer, 10 to 50% by weight of the vinyl cyanide compound and 10 to 60% by weight of the reaction solvent.

In addition, in the present invention, the reaction mixture may further include a molecular weight modifier to minimize the formation of the gel to proceed the polymerization uniformly. In the present invention, the molecular weight regulator is preferably used in an amount of 0.001 to 0.5 parts by weight based on 100 parts by weight of the reaction mixture. If the content of the molecular weight modifier is less than 0.001 part by weight, the effect of inhibiting gel formation is insignificant. If the content of the molecular weight regulator is more than 0.5 part by weight, there is a problem in that the effect of improving the mechanical properties cannot be obtained because there is no molecular weight increasing effect. The molecular weight modifier that can be used in the present invention is preferably a mercaptan-based compound, specifically, at least one selected from the group consisting of n-dodecyl mercaptan, t-dodecyl mercaptan and n-octyl mercaptan to be used. Can be.

In this step, the mixing initiator is preferably used by mixing a tetrafunctional group-containing initiator having a 1 hour half-life temperature of 100 to 125 ℃ and a bifunctional group-containing initiator having a 1 hour half-life temperature of 130 to 160 ℃ in an appropriate content ratio. Specifically, in the present invention, the mixing initiator has a content ratio of a bifunctional group-containing initiator 4-functional group-containing initiator having a 1-hour half-life temperature of 130 to 160 ° C with respect to a 4-functional group-containing initiator having a 1-hour half-life temperature of 100 to 125 ° C. It is preferably made of a weight ratio of 1: 1. When the content of the 4-functional group-containing initiator having a 1-hour half-life temperature of 100 to 125 ° C is less than the content range, the effect of increasing the molecular weight is insignificant, and if the content exceeds the content range, the effect of increasing the conversion rate is not preferable.

In the present invention, the tetrafunctional group-containing initiator having the one-hour half-life temperature of 100 to 125 ° C serves to increase the molecular weight in the initial stage of polymerization. When the polymerization proceeds with the initiator, the molecular weight is generally smaller than when the initiator is not used. However, when the tetrafunctional initiator according to the present invention is used, since the addition of monomers occurs at four functional groups in the initiator, there is an effect of increasing the molecular weight. In the present invention, the tetrafunctional group-containing initiator may be used without limitation, a thermal polymerization initiator having a half-life temperature of 100 to 125 ° C for 1 hour. Specifically, 2,2-bis (4,4-di-t-butylperoxy cyclohexyl) propane, dialkyl peroxides, peresters, peroxymonocarbonates, It is preferable to use at least one selected from the group consisting of peroxydicarbonates, diacyl peroxides, and peroxyketals, more preferably 2,2-bis ( 4,4-di-t-butylperoxy cyclohexyl) propane In the present invention, the one-hour half-life temperature of the tetrafunctional group-containing initiator is limited to 100 to 125 ° C, which has an one-hour half-life temperature in the above range. This is because the effect of improving the molecular weight at the initial stage of reaction and the polymerization efficiency is large when the reaction time is used, and when the one-hour half-life temperature of the tetrafunctional group-containing initiator is less than 100 ° C, the polymerization time is excessively increased and the reaction is not efficient. And, if it exceeds 125 ℃ there may occur a start of another mixed initiator is not preferred because there is a problem that the molecular weight increasing effect is not large.

In the present invention, the bifunctional group-containing initiator having the 1 hour half-life temperature of 130 to 160 ° C increases the molecular weight of the polymer in the second half of the reaction and increases the conversion rate. In the present invention, the bifunctional group-containing initiator may be used without limitation, the thermal polymerization initiator having a half-life temperature of 130 to 160 ° C for 1 hour. Specifically, bis (1-methyl-1-phenylethyl) peroxide (bis (1-methyl-1-phenylethyl) peroxide), t-hexyl peroxyneodecanoate or t-hexyl It is preferable to use peroxy-2-ethylhexanoate (t-hexyl peroxy-2-ethylhexanoate), more preferably bis (1-methyl-1-phenylethyl) peroxide. In the present invention, the 1-hour half-life temperature of the bi-functional group-containing initiator is limited to 130 to 160 ° C., when the bi-functional group-containing initiator having a 1-hour half-life temperature in the above range is used, the effect of improving the molecular weight in the late reaction is large and the reaction conversion rate Because it can be enlarged. When the 1-hour half-life temperature of the bifunctional initiator is less than 130 ° C., the activity of the bifunctional group-containing initiator is increased at low temperatures, so the activity ratio of the tetrafunctional group-containing initiator is relatively low, so that the effect of increasing the initial molecular weight of the reaction may be insignificant, 160 If the temperature is exceeded, the polymerization temperature must be excessively high, so that the efficiency of the reaction decreases and the internal pressure of the reactor may be excessively increased, which is not preferable.

In this step, the reaction mixture and the mixing initiator is preferably added separately through a separate inlet. The reason for this is that the reaction mixture contains a molecular weight regulator such as t-dodecyl mercaptan (TDDM), and when the reaction mixture is mixed with the initiator, the molecular weight regulator may encounter an initiator and a very strong exothermic reaction may occur. This is because control of the reaction is not easy.

The reactor of the polymerization apparatus used in the present invention is not particularly limited, but a stirred tank reactor in which a heat exchanger is attached to the front end of the reactor is preferable.

In the present invention, the reaction mixture may be added to each reactor in a predetermined ratio to make the composition of the resulting polymer uniform and reduce gel formation. That is, only 70 to 90% by weight of the total reaction mixture is added to the first reactor, and the remaining 10 to 30% by weight of the remaining reaction mixture is added to the second reactor. This principle is explained as follows. That is, the aromatic vinyl monomer in the reaction mixture is generally higher in boiling point than the vinyl cyanated compound, and most of the gas evaporated in the reactor is composed of the vinyl cyanated compound. Therefore, non-uniform polymers or gels may be generated due to non-uniform mixing of the condensate or the reaction liquid with the liquid containing a large amount of components of the vinyl cyanide compound back into the reactor. Therefore, only 70 to 90% by weight of the reaction mixture is added to the first reactor, the remaining amount of 10 to 30% by weight of the reaction mixture is introduced into the second reactor, and the input method is at an inlet through which the condensate condensed in the first reactor is refluxed. By mixing together with the condensate, the composition variation of each reactor may be reduced, and the condensate component may be diluted with the remaining reaction mixture to be injected to solve the gel formation problem.

The polymerization process in this step is preferably carried out under the conditions of constant temperature, pressure and residence time in order to increase the conversion and molecular weight. Specific polymerization reaction conditions are preferably polymerized by the reaction mixture mixture and the mixed initiator is maintained in the reactor for 1.5 to 3 hours while maintaining a temperature of 100 to 160 ℃ and a pressure of 1.5 to 4 kg / cm ³ . When it is out of the said range, since the activation of the said tetrafunctional group containing initiator and the bifunctional group containing initiator does not occur smoothly, reaction conversion and a molecular weight increase effect are not large, it is preferable to perform superposition | polymerization within the said range.

(b) secondary polymerization stage

This step is to move the reaction product of the first polymerization produced in step (a) to the second reactor continuously and then to add the remaining amount of the reaction mixture while the additional polymerization takes place under the appropriate polymerization conditions, the predetermined molecular weight and conversion rate It is a step of forming a copolymer of an aromatic vinyl monomer having a vinyl cyanide compound.

In this step, it is preferable to add a predetermined amount of the reaction mixture as described in the description of the step (a). The amount used is preferably 10 to 30% by weight, which is the remaining amount used in the step (a) of the reaction mixture. If the amount is less than 10% by weight, it is difficult to form a homogeneous polymer and gel formation may be increased. If the amount is more than 30% by weight, the effect of increasing the reaction conversion rate and molecular weight is not preferable .

The reactor of the polymerization apparatus that can be used in this step is not particularly limited, but a part of the unreacted monomer or the reaction solvent evaporated through the pressure control of the reactor is returned to the reactor while passing through the condenser, the storage tank and the temperature of the reactor is increased. It is preferred that the device is designed to be adjusted.

The polymerization method in this step is also preferably carried out under the conditions of a constant temperature, pressure and residence time in order to increase the conversion and molecular weight as in the polymerization method of step (a). Specific polymerization conditions are 1.5 to 3 hours while maintaining the temperature of 100 to 160 ℃ and the pressure of 1.5 to 4 kg / cm ³ of the reaction mixture of the first polymerization and the additionally introduced reaction mixture moved in the step (a) It is preferable to stay and polymerize. When it is out of the said range, since activation of a tetrafunctional group containing initiator and a bifunctional group containing initiator does not occur smoothly, reaction conversion and a molecular weight increase effect are not large, it is preferable to perform superposition | polymerization within the said range.

(c) polymer separation step

This step is a step of recovering the unreacted monomer and the reaction solvent by separating the polymer product formed in step (b) to a recovery tank.

The method for recovering the unreacted monomer and the reaction solvent in this step is not particularly limited and may be a method commonly used in the art. To explain a specific example, the heat exchanger is attached to the reaction product formed and discharged in step (b) to maintain a temperature of 200 to 250 ℃ and a vacuum pressure of 50 torr or less, preferably 20 to 30 torr The unreacted monomer and the reaction solvent can be recovered by volatilizing the unreacted monomer and the reaction solvent and then condensing again to recover the unreacted monomer and the reaction solvent. The separated polymer is processed into pellets while passing through a transfer pump extruder.

The present invention may further include the step of re-injecting the unreacted monomer and the reaction solvent recovered in the step (c) to the step (a). Through the re-input of the unreacted monomer and the reaction solvent, raw materials can be saved and the amount of organic compounds can be reduced. The method of re-injecting the unreacted monomer and the reaction solvent into the step (a) is not particularly limited. Looking at the specific method, an input line to which a separate input control device is attached is transferred to the first reactor of step (a). This can be done by connecting.

Since the copolymer of the aromatic vinyl monomer and the vinyl cyanide compound produced by the production method according to the present invention has a high molecular weight, the mechanical properties such as tensile strength and impact strength are excellent, and physical properties such as heat resistance and oxidation stability are also good.

The copolymer of the aromatic vinyl monomer and the vinyl cyanide compound prepared by the production method according to the present invention may be used alone or may be used in combination with another resin, and the copolymer of the aromatic vinyl monomer and the vinyl cyanide compound may be blended. The physical properties of the resin can also be improved.

In the above, the method for preparing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound according to the present invention has been described.

When preparing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound by using the preparation method according to the present invention, a mixed initiator of a tetrafunctional group-containing initiator having a low 1-hour half-life temperature and a bifunctional group-containing initiator having a high 1-hour half-life temperature is used. By increasing the molecular weight at the beginning of the reaction and allowing the polymerization to occur continuously in the later stage of the reaction, the conversion of the reaction can be improved.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

Example

Example  One

A reaction mixture was obtained by mixing 100 parts by weight of a mixture consisting of 64% by weight of styrene, 22.3% by weight of acrylonitrile, and 13.7% by weight of toluene and 0.35 part by weight of t-dodecylmercaptan. Two 40-liter vertical cylindrical reactors equipped with a stirring vessel were continuously arranged in series, and 70% by weight of the reaction mixture was continuously introduced into the first reactor of the polymerization apparatus, and the half-life temperature was 114 hours as a tetrafunctional initiator. 0.025 parts by weight of 2,2-bis (4,4-di-t-butylperoxy cyclohexyl) propane (PTA from NOF) and a bifunctional group-containing initiator at bis (1-methyl 0.05 parts by weight of a mixed initiator of 0.025 parts by weight of -1-phenylethyl) peroxide (DCP of NOF) was continuously introduced through a separate inlet connected to the first reactor, and the internal temperature of the first reactor was increased to 130 ° C. The primary polymerization was carried out by holding for 1.5 to 2.5 hours while maintaining the internal pressure of the reactor 1 to 4 kg / cm ³ .

After continuously moving the produced primary polymerization product to the second reactor, the remaining temperature of the reaction mixture is continuously added to the second reactor while continuously adding 30% by weight to the second reactor, the internal temperature of the second reactor to 130 ~ 160 ℃, The secondary polymerization was carried out by maintaining the internal pressure of the reactor 2 at 1.5 to 4 kg / cm ³ for 1.5 to 2.5 hours.

The produced secondary polymerization product was introduced into a volatilization tank equipped with a heat exchanger maintaining a temperature of 200 to 250 ° C. and a vacuum pressure of 20 to 30 torr to volatilize the unreacted monomer and the reaction solvent, and then recovered by condensation. The polymer was obtained separately.

Comparative example  One

0.025 parts by weight of 1,1-bis (t-butylperoxy) cyclohexane (PHC from NOF Co., Ltd.) having a 1 hour half-life temperature of 111 ° C without using a tetrafunctional group-containing initiator and having the bisity of Example 1 It carried out similarly to Example 1 except having used 0.05 weight part of mixing initiators mixed with 0.025 weight part of (1-methyl-1- phenylethyl) peroxides.

Comparative example  2

0.025 parts by weight of t-butylperoxy isopropyl monocarbonate (BPC manufactured by SEKI Atofina), which is a monofunctional group-containing initiator having a half-life temperature of 118 ° C for 1 hour without using a tetrafunctional group-containing initiator, was used as the bis (1-methyl It carried out similarly to Example 1 except having used 0.05 weight part of mixing initiators mixed with 0.025 weight part of -1-phenylethyl) peroxides.

The composition of Example 1 and Comparative Examples 1 and 2 are summarized in Table 1 below.

division Example 1 Comparative Example 1 Comparative Example 2 Styrene 64 64 64 Acrylonitrile 22.3 22.3 22.3 toluene 13.7 13.7 13.7 t-dodecyl mercaptan 0.35 0.35 0.35 Mixed initiator PTA / DCP = 0.025 / 0.025 PHC / DCP = 0.025 / 0.025 BPC / DCP = 0.025 / 0.025

PTA = 2,2-bis (4,4-di-t-butylperoxy cyclohexyl) propane

DCP = bis (1-methyl-1-phenylethyl) peroxide

PHC = 1,1-bis (t-butylperoxy) cyclohexane

BPC = t-butylperoxy isopropyl monocarbonate

(Performance evaluation)

In the polymerization process according to Example 1 and Comparative Examples 1 and 2, the polymer was sampled when a certain time had elapsed after the start of polymerization, and molecular weight and conversion were measured. Sampling time was measured 15 minutes, 30 minutes, 45 minutes after the start of the polymerization and the molecular weight and conversion by the following method.

Molecular weight measurement

Molecular weight was measured using gel permeation chromatography (GPC). The analyzer used Waters' M1515 and the software used Breeze's Chromatography Manager Software. The sample to be used for molecular weight measurement was made by dissolving 20 ml of THF (tetrahydrofuran) in 0.02 g of the sample, filtered through a 0.45 μm filter, and put into a GPC vial (4 ml). Prior to measuring the sample, the solvent was maintained at a rate of 1.0 ml / min from 1 hour before (THF), 25 minutes of running type, 150 µl of injection volume, 1.0 ml / min of flow rate, and pump Pump mode isocratic, detector (RI) detector was measured under the conditions of 40 ℃. At this time, calibration was performed using the PS standard.

Conversion rate measurement

The reactor used in the experiment was a vial type reactor of ACE glass company, and temperature control was performed using an oil bath. When the experiment was plugged tightly to prevent the reaction from leaking. When the vial was removed from the oil bath according to the reaction time, methanol was immediately poured to precipitate the polymer, or soaked in cold water to inhibit the polymerization, and then methanol was poured to allow the polymer to precipitate. The initial mass of the reactant was accurately measured, and the reacted polymer was vacuum dried and weighed. Then, the solvent content in the reactant was subtracted and the weight of the polymer was divided based on the monomer. That is, the conversion rate is measured by the ratio of the weight of the polymer after the polymer reaction and the weight of the monomer before the reaction.

The performance evaluation results are summarized in Table 2 below.

Minutes Example 1 Comparative Example 1 Comparative Example 2 Molecular Weight Conversion rate Molecular Weight Conversion rate Molecular Weight Conversion rate 15 306720 25.0 228982 51.9 213170 46.7 30 284133 55.4 239050 65.6 223839 64.0 45 283176 66.5 248983 70.4 231359 70.1

As can be seen from the results of Table 2 above, in the case of solution polymerization of styrene and acrylonitrile according to the present invention, when a mixed initiator containing a tetrafunctional group-containing initiator and a bifunctional group-containing initiator is used, It can be seen that the molecular weight is significantly increased compared to the case of Comparative Example 1 in which the functional group-containing initiator was mixed, or the Comparative Example 2 in which the bifunctional group-containing initiator and the monofunctional group-containing initiator were mixed. It can be seen that the level is almost the same. In the results of Table 2, the molecular weight decreases with time, it is determined that the number of radicals increased due to decomposition of the high-temperature initiator in the reactant with time.

When preparing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound by the preparation method according to the present invention, the tetrafunctional group-containing initiator increases the molecular weight of the initial stage of polymerization, and the bifunctional group-containing initiator increases the molecular weight of the late stage of polymerization. Since the conversion is increased, the copolymer of the aromatic vinyl monomer and the vinyl cyanide compound according to the preparation method of the present invention has a large molecular weight and a high conversion ratio of the polymerization reaction, so that the reaction can proceed efficiently.

Although the present invention has been described above through specific embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the technical idea of the present invention, and such modifications and modifications belong to the appended claims.

Claims (12)

(a) 70 to 90% by weight of the total amount of the reaction mixture prepared by mixing the aromatic vinyl monomer, the vinyl cyanide compound, and the reaction solvent with a tetrafunctional initiator containing one hour half-life temperature of 100 to 125 ° C. and one hour half-life temperature of 130 to 130 ° C. Continuously injecting a mixed initiator prepared by mixing a bifunctional group-containing initiator having a temperature of 160 ° C. into a first reactor to carry out a first polymerization; (b) continuously polymerizing the reaction product formed in the first reactor by continuously adding 10 to 30 wt% of the remaining amount of the reaction mixture into the second reactor while continuously moving the reaction product formed in the second reactor; And (c) recovering the unreacted monomer and the reaction solvent by separating the reaction product formed in the second reactor into a recovery tank and separating the polymer; Method for producing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound comprising a. The method of claim 1, The aromatic vinyl monomer of step (a) is at least one member selected from the group consisting of styrene, α-methyl styrene and p-methyl styrene. The method of claim 1, The vinyl cyanated compound of step (a) is at least one member selected from the group consisting of acrylonitrile, methacrylonitrile and ethacrylonitrile. The method of producing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound. The method of claim 1 The reaction solvent of step (a) is at least one selected from the group consisting of toluene, tetrahydrofuran, ethyl benzene, benzene, cyclohexanone and dimethylroformamide, the air of the aromatic vinyl monomer and vinyl cyanide compound Process for the preparation of coalescing. The method of claim 1, The reaction mixture of step (a) is 50 to 90% by weight of the aromatic vinyl monomer, 10 to 50% by weight of the vinyl cyanide compound and 10 to 60% by weight of the reaction solvent of the aromatic vinyl monomer and vinyl cyanide compound Method of Preparation of Copolymer. The method of claim 1, The method of producing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound, characterized in that the reaction mixture of step (a) further comprises a molecular weight regulator in an amount of 0.001 to 0.5 parts by weight based on 100 parts by weight of the reaction mixture. The method of claim 6, The molecular weight modifier is at least one selected from the group consisting of n-dodecyl mercaptan, t-dodecyl mercaptan and n-octyl mercaptan, the method of producing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound. The method of claim 1, The mixed initiator of step (a) has a content ratio of a bifunctional group-containing initiator 4-functional group-containing initiator having a 1-hour half-life temperature of 130 to 160 ° C compared to a 4-functional initiator having a 1-hour half-life temperature of 100 to 125 ° C. Method for producing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound, characterized in that consisting of 5 to 1: 1 parts by weight. The method of claim 1, The tetrafunctional group-containing initiator having the one-hour half-life temperature of 100 to 125 ° C in step (a) is 2,2-bis (4,4-di-t-butylperoxy cyclohexyl) propane Method for producing a copolymer of a vinyl monomer and a vinyl cyanide compound. The method of claim 1, The bifunctional group-containing initiator having the one-hour half-life temperature of 130 to 160 ° C in step (a) is bis (1-methyl-1-phenylethyl) peroxide, t-hexyl peroxy neodecanoate or t-hexyl A method for producing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound, which is peroxy-2-ethylhexanoate. The method of claim 1, Method for producing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound, characterized in that the reaction mixture of step (a) and the mixing initiator is separated and added through a separate inlet. The method of claim 1, The method of producing a copolymer of an aromatic vinyl monomer and a vinyl cyanide compound further comprises the step of re-injecting the monomer and the reaction solvent recovered in the step (c) to the step (a).