KR20060097999A - METHOD OF PREPARING alpha;-METHYLSTYRENE/ACRYLONITRILE COPOLYMER WITH HIGH HEAT-RESISTANCE - Google Patents

Abstract

The present invention relates to a method for producing a heat resistant copolymer, and more particularly, to a method for producing a heat resistant copolymer containing alphamethylstyrene and acrylonitrile by a continuous bulk or solution polymerization method.

The method for producing a heat resistant copolymer according to the present invention enables efficient operation by increasing the conversion ratio of monomers to be supplied and also lowers the content of monomers remaining in the heat resistant copolymers to be produced, thereby obtaining a heat resistant copolymer having excellent physical properties. It works. In addition, by mixing the alpha methyl styrene- acrylonitrile copolymer prepared by the production method according to the present invention to the ABS resin, there is an effect that can be obtained a heat resistant ABS resin composition excellent in heat resistance.

Heat Resistant Copolymer, Alphamethylstyrene, Acrylonitrile, Multifunctional Organic Peroxide Initiator, Stirred Tank Reactor, Branching, Volatilization Tank

Description

Method for preparing alpha methyl styrene / acrylonitrile copolymer having excellent heat resistance {Method of preparing α-methylstyrene / acrylonitrile copolymer with high heat-resistance}

1 is a process flow diagram showing an embodiment of a stirred vessel reactor system for preparing an alpha methylstyrene / acrylonitrile heat resistant copolymer according to the present invention.

<Explanation of symbols for the main parts of the drawings>

110: reaction mixture 112: initiator

120: first reaction product 122: second reaction product

124: heat resistant copolymer 130: unreacted monomer and solvent

132: condensed unreacted monomer and solvent

210: first stirred tank reactor 220: second stirred tank reactor

230: gasoline 240: condenser

The present invention relates to a method for producing a copolymer having excellent heat resistance, and more particularly, to a method for producing a copolymer having excellent heat resistance containing alphamethylstyrene and acrylonitrile by a continuous block or solution polymerization method.

Acrylonitrile-butadiene-styrene copolymer resin (hereinafter referred to as 'ABS resin') is a material having excellent rigidity, impact resistance, surface gloss, and chemical resistance. It is an industrial material widely used in the field. However, since the ABS resin has low heat resistance, there are limitations in applications such as automotive interiors and exterior materials requiring heat resistance, such as restrictions on use.

Therefore, various methods for overcoming these disadvantages have been sought, using a method of introducing a monomer having excellent heat resistance or adding an inorganic material to a part of the composition constituting the ABS resin.

As a general method of introducing monomers having excellent heat resistance, first, a maleimide-based or alphamethylstyrene-based monomer having excellent heat resistance may be added during the polymerization process, and another method may be a heat-resistant copolymer containing the monomer having excellent heat resistance. Is mixed with ABS resin.

The copolymer having excellent heat resistance is usually prepared by copolymerizing or tertiary copolymerizing an alphamethylstyrene monomer or a maleimide monomer with a vinyl cyan compound such as acrylonitrile and / or an aromatic vinyl monomer such as styrene.

On the other hand, the maleimide monomer has a very fast polymerization rate, which makes it difficult to control the reaction temperature. In addition, the monomer such as alphamethylstyrene has a low polymerization temperature, so the polymerization rate is slow. As a result, the reaction time is long.

Due to the characteristics of the monomers, a method of preparing a copolymer having excellent heat resistance is usually prepared by emulsion polymerization in a batch process having a low reaction temperature and easy control of the reaction time.

There are many known methods for producing a copolymer resin having excellent heat resistance using the emulsion polymerization method (US Patent No. 3,010,936, US Patent No. 3,367,995, US Patent No. 4,774,287, etc.). The problems inherent in the law (deterioration of quality due to impurities such as emulsifiers and flocculants, decrease in heat resistance, etc.) are retained.

Accordingly, other polymerization methods have been sought that do not include the problems inherent in such emulsion polymerization. US Pat. No. 4,795,780 discloses a copolymer resin containing alphamethylstyrene and acrylonitrile using a bulk polymerization method. A manufacturing method is disclosed. In order to overcome the low conversion rate of alphamethylstyrene, the patent continuously adds alphamethylstyrene and acrylonitrile monomers to a reactor in which two agitator reactors are connected in series, evaporates in a second agitator reactor and then passes through a condenser. The condensed condensate is introduced into the first stirred tank reactor. However, this method used AIBN (azobisisobutyronitrile) as an initiator, which is not effective in increasing the conversion rate and molecular weight in the copolymerization of alphamethylstyrene and acrylonitrile.

In the manufacture of heat resistant copolymers, various methods have been proposed to solve the above problems and have been partially effective but are not a fundamental alternative and still have room for improvement.

The first technical problem to be achieved by the present invention is to provide a method for preparing an alphamethylstyrene-acrylonitrile copolymer which solves the problem of low conversion and low molecular weight in the reaction of copolymerizing alphamethylstyrene and acrylonitrile.

The second technical problem to be achieved by the present invention is to provide an alphamethylstyrene-acrylonitrile copolymer prepared by the above production method.

The third technical problem to be achieved by the present invention is to provide a heat resistant ABS resin composition comprising the alphamethylstyrene-acrylonitrile copolymer.

The present invention, in order to achieve the first technical problem, in the two or more stirred tank reactor system connected in series, the reaction mixture containing alphamethylstyrene, acrylonitrile, and a solvent, the first stirring of the stirred tank reactor system It is supplied to a tank reactor, and 0.05 to 0.5 parts by weight of a multifunctional organic peroxide initiator is supplied to the first stirred tank reactor with respect to 100 parts by weight of the reaction mixture, at least one of the stirred tank reactor after the second stirred tank reactor Provided is a method for producing a heat resistant copolymer characterized in that it supplies 0.005 to 0.05 parts by weight of the multifunctional organic peroxide initiator with respect to 100 parts by weight of the reactants of the stirred tank reactor.

In order to achieve the second technical problem, the present invention is prepared by the above-described manufacturing method, the alpha methyl styrene content is 68 to 75 parts by weight, the acrylonitrile content is 25 to 32 parts by weight based on 100 parts by weight of the copolymer, An alphamethylstyrene-acrylonitrile copolymer having a weight average molecular weight of 90,000 to 110,000 and a glass transition temperature of 123 ° C or higher is provided.

The present invention provides a heat resistant ABS resin composition comprising 20 to 50 parts by weight of the alphamethylstyrene-acrylonitrile copolymer and 50 to 80 parts by weight of ABS resin in order to achieve the third technical problem.

Hereinafter, the present invention will be described in more detail with reference to FIG. 1.

Figure 1 shows a process flow diagram showing an embodiment of the stirred tank reactor system for producing an alpha methyl styrene / acrylonitrile heat resistant copolymer according to the present invention.

The present invention relates to a method for producing a high quality heat resistant copolymer using a continuous bulk or solution polymerization method. In particular, a reaction mixture of alphamethylstyrene, acrylonitrile and a solvent is introduced into a stirred tank reactor connected in series, and a multifunctional organic A peroxide initiator is introduced into a first stirred tank reactor and at least one downstream stirred tank reactor to cause a polymerization reaction, thereby producing a heat resistant copolymer. In addition, by supplying the final reaction product to the volatilization to separate the unreacted monomers and solvents, and condensation of the separated unreacted monomers and solvents to be fed back to the stirred tank reactor to lower the content of residual monomers remaining in the final product as well as monomers In addition, the conversion rate is also increased, thereby improving the efficiency of the process operation.

The starting materials for preparing the heat resistant copolymer are a reaction mixture comprising an alphamethylstyrene monomer and an acrylonitrile monomer and a polyfunctional organic peroxide initiator. The reaction mixture may further include a solvent.

Alphamethylstyrene monomer is preferably included 50 to 75 parts by weight based on 100 parts by weight of the reaction mixture. In the heat-resistant copolymer containing alpha methyl styrene, when the content of alpha methyl styrene in the reaction mixture added exceeds 75 parts by weight, the proportion of the structure in which three or more consecutive alpha methyl styrene is bonded to the chain of the resulting copolymer is rapidly increased. Thus, a structure in which three or more alphamethylstyrenes are bonded in series is a fragile structure that is easily decomposed to heat. In addition, if the content of alpha methyl styrene is less than 50 parts by weight, the heat resistance is weak and there is a disadvantage that the color turns yellow when heated.

The acrylonitrile monomer is preferably included 25 to 40 parts by weight based on 100 parts by weight of the reaction mixture. When the amount of acrylonitrile monomer in the added reaction mixture exceeds 40 parts by weight, an insoluble gel polymer containing a large amount of acrylonitrile is formed. The gel polymer is weak to heat and acts as a red or black foreign material when heated to improve the appearance of the product. Damage. In addition, when less than 25 parts by weight of acrylonitrile monomer is used in the added reaction mixture, it is difficult to secure sufficient physical properties.

The solvent is preferably included 0.1 to 15 parts by weight based on 100 parts by weight of the reaction mixture. When the solvent content in the reaction mixture added in the heat-resistant copolymer exceeds 15 parts by weight, it is difficult to secure physical properties such as molecular weight and glass transition temperature of the heat-resistant copolymer, resulting in the effect of lowering the productivity of the heat-resistant copolymer. In addition, when the solvent content is less than 0.1 parts by weight, the viscosity is too high, causing problems in heat transfer and material transfer.

In addition, since alpha methyl styrene has a low polymerization temperature, it has a low conversion ratio and an average molecular weight, and thus it is necessary to overcome such disadvantages for commercial development. In order to solve this problem, the present inventors use a polyfunctional organic peroxide initiator, and the conversion rate is achieved by branching the polyfunctional organic peroxide initiator to at least one of the reactors connected in series as well as the first stirring vessel reactor. It has been found that a high quality heat resistant copolymer having a high average molecular weight can be produced.

The amount of the initiator added to the first stirred tank reactor is preferably 0.05 to 0.5 parts by weight based on 100 parts by weight of the reaction mixture. When the amount of the initiator in the injected reaction mixture exceeds 0.5 parts by weight, it is not only difficult to apply to the process by causing a rapid reaction, but also causes a decrease in the physical properties of the heat resistant copolymer. In addition, when the amount of the initiator is less than 0.05 parts by weight in the added reaction mixture, rather than copolymerization by the initiator to form a thermally polymerized form of polymerization by forming oligomers, physical properties of the heat-resistant copolymer such as molecular weight and glass transition temperature, productivity, etc. Lowers.

The amount of the initiator introduced into at least one stirred tank reactor of the stirred tank reactor after the second stirred tank reactor is preferably 0.005 to 0.05 parts by weight based on 100 parts by weight of the contents of the stirred tank reactor. When the amount of the initiator in the charged reaction mixture exceeds 0.05 parts by weight, it is not only difficult to apply to the process by causing a rapid reaction, but also causes a decrease in the physical properties of the heat resistant copolymer. In addition, when the amount of the initiator is less than 0.005 parts by weight of the reaction mixture, the polymerization is formed by thermal polymerization rather than copolymerization by the initiator to form oligomers, lower the physical properties of the heat-resistant copolymer such as molecular weight and glass transition temperature, productivity, etc. Lowers.

As the polyfunctional initiator used in the present invention, 1,1-bis (tertiarybutylperoxy) -2-methylcyclohexane, 1,1-bis (tertiarybutylperoxy) cyclohexane, 1,1-bis ( Tertiarybutylperoxy) -3,3,5-trimethylcyclohexane, 2,2-bis (tertarybutylperoxy) butane, or 2,2-bis (4,4-dibutylbutyloxyoxyhexyl) Preference is given to using propane.

The reactor of the polymerization apparatus used in the present invention is not particularly limited, but two or more stirring vessel reactors should be connected in series. In particular, the first stirred tank reactor is preferably attached to a heat exchanger capable of supplying or removing heat to the reactants in front of the reactor. That is, it is preferable to further include the step of supplying or removing heat to the reaction mixture by installing a heat exchanger in front of the first stirred tank reactor.

In addition, the reactor after the second stirred tank reactor is preferably an evaporative stirred tank reactor including a reservoir, a condenser, and a pressure control plate.

More specifically, the polymerization reaction of alpha methyl styrene is very low, there is a case that the amount of heat to be removed in the first stirred tank reactor is very low, or rather it is necessary to supply heat to the reaction mixture. Therefore, although not shown in FIG. 1, it is preferable that a heat exchanger is installed in front of the stirring vessel reactor for uniform temperature control in the first stirring vessel reactor.

The reactor after the second stirred tank reactor is preferably a portion of the unreacted monomer or solvent evaporated through the pressure control of the reactor to be fed back to the reactor while passing through the condenser, the storage tank.

It is preferable that the reaction temperature in each stirring tank reactor is 100-130 degreeC, and the average residence time in each stirring tank reactor of a reactant is 2 to 4 hours. When the reaction temperature in each agitator reactor is lower than 100 ° C, the conversion rate is lowered, and the molecular weight is difficult to control. When the reaction temperature in each agitator reactor is higher than 130 ° C, the molecular weight is lowered and the reaction occurs abruptly, causing The disadvantage is that control becomes difficult. If the residence time is less than 2 hours, it is difficult to obtain a sufficient conversion rate, and if it is 4 hours or more, it is difficult to apply the process due to the increase of the conversion rate and viscosity of the heat resistant copolymer.

The solvent is used for the purpose of controlling the reaction viscosity and the reaction temperature, but ethylbenzene, toluene, xylene, methyl ethyl ketone, etc. may be used, but toluene having a low boiling point for the convenience of separation due to the high boiling point of alphamethylstyrene. , Methyl ethyl ketone, or a mixture thereof is preferred.

The reaction product thus produced is added to a volatilization tank maintaining a temperature of 200 to 250 ° C. and a pressure of 50 torr or less, preferably 20 to 30 torr, to volatilize the unreacted monomer and the solvent to prepare a heat resistant copolymer. When the pressure exceeds 50 torr, separation of unreacted monomers is not sufficient. In addition, when the temperature of the volatilization tank is less than 200 ° C, separation of the unreacted monomers is not sufficient, and the viscosity is too high, making it difficult to process, and when the temperature of the volatilization tank exceeds 250 ° C, it is economically disadvantageous.

The prepared heat resistant copolymer is processed into pellets while passing through an extruder, and the unreacted monomers and solvents volatilized are condensed through a condenser and then introduced into a stirred tank reactor. Through the above process, the amount of unreacted monomer remaining in the heat resistant copolymer can be maintained at a level of 2000 ppm or less.

As can be seen in FIG. 1, which is an embodiment of the present invention, the first agitator reactor 210 and the second agitator reactor 220 are connected in series, and the reaction mixture 110 is a first agitator reactor 210. ) Is being put into. The first reaction product 120 generated by the reaction in the first agitator reactor 210 is introduced into a second agitator reactor 220 connected in series, and an initiator is added to the first agitator reactor and the second agitator reactor, respectively. 112 is being injected. The conversion rate of the second reaction product 122 is further increased due to the initiator 112 injected directly into the second stirred tank reactor 220. The second reaction product 122 enters the volatilization tank 230 and undergoes a separation and recovery step. The second reaction product 122 that enters the volatilization tank 230 is volatilized and separated by unreacted monomer and solvent 130 under the conditions in the volatilization tank, and the remainder remains as the heat resistant copolymer 124 to proceed to the next process. Unreacted monomer and solvent 130 are condensed in condenser 240. The condensed unreacted monomer and the solvent 132 are supplied to the first stirred tank reactor 210 to participate in the reaction again.

Alpha methylstyrene content of 68 to 75 parts by weight, acrylonitrile content of 25 to 32 parts by weight, weight average molecular weight of 90,000 to 110,000, and glass transition temperature based on 100 parts by weight of the copolymer as described above. It is possible to prepare an alphamethylstyrene-acrylonitrile copolymer having a 123 ° C or higher.

In addition, a heat resistant ABS resin composition including 20 to 50 parts by weight of the alphamethylstyrene-acrylonitrile copolymer and 80 to 50 parts by weight of ABS resin may be prepared. If the content of the alpha methyl styrene-acrylonitrile copolymer is less than 20 parts by weight, sufficient heat resistance may not be obtained. If the content of the alpha methyl styrene-acrylonitrile copolymer exceeds 50 parts by weight, the strength and surface gloss may be degraded.

Hereinafter, the configuration and effects of the present invention will be described in more detail with specific examples and comparative examples, but the examples are only intended to more clearly understand the present invention and are not intended to limit the scope of the present invention.

Example 1

The reaction mixture was prepared by connecting two stirred tank reactors each having a capacity of 30 liters and 50 liters in series, mixing 65 parts by weight of alphamethylstyrene, 30 parts by weight of acrylonitrile, and 5 parts by weight of toluene, and prepared as described above. The reaction mixture was continuously introduced into the first stirred tank reactor at a flow rate of 10 l / hr, and 0.1 parts by weight of initiator was continuously added to the first stirred tank reactor based on 100 parts by weight of the reaction mixture. The second initiator was continuously fed with 0.01 parts by weight of the same initiator to 100 parts by weight of the content of the second reactor. As an initiator, 1,1-bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane was used.

The volume occupied by the reactants was maintained at 30 l in consideration of the residence time in both the first and second reactors.

The temperature of the first stirred tank reactor was maintained uniformly at 110 ° C., and the temperature of the second stirred tank reactor was also kept uniformly at 110 ° C.

As a result of the polymerization reaction, the unreacted monomer and the solvent were removed while maintaining a temperature of 250 ° C. and 20 torr in a volatilized tank equipped with a heat exchanger, and the remaining reaction product (A) was processed into pellets through an exhaust pump and an extruder.

The pellets were measured for physical properties such as weight average molecular weight, acrylonitrile content, melt index, thermal decomposition loss of resin, monomer residual in resin, oligomer content and glass transition temperature.

In addition, the resin composition (B) produced by mixing 50 parts by weight of the heat-resistant copolymer prepared above, 40 parts by weight of styrene-butadiene-acrylonitrile graft copolymer and 10 parts by weight of acrylonitrile-styrene copolymer resin is extruded. After the injection specimen was produced in the injection machine and the impact strength, melt index and heat deflection temperature (HDT) was measured using the specimen.

[Measurement Method]

In Examples and Comparative Examples, physical properties were evaluated in the following manner.

Weight average molecular weight (Mw)

0.2 g of the prepared heat resistant copolymer was dissolved in 20 ml of tetrahydrofuran (THF), filtered through a 0.45 μm filter, and then gel averaged by using gel permeation chromatography (GPC: gel permeation chromatography, Waters Maxima820). It was. The injection time was 25 minutes, the number of injections once, and the column temperature was measured under measurement conditions of 40 ° C.

Content of Acrylonitrile

The content was analyzed using elemental analysis equipment (EA).

Melt index

It was measured according to ASTM D-1238 (220 ° C., 10 kg).

Pyrolysis Reduction of Resin

The resin was placed in a plate-shaped aluminum silver foil and heated in an oven maintained at 230 ° C. for 1 hour, and then the weight difference was measured before and after heating.

Monomer residual and oligomer content in resin

The prepared heat resistant copolymer was dissolved in THF (10 wt%) and analyzed by gas chromatography (GC / FID). (Agilent 6890N)

Glass transition temperature

It was measured using differential scanning calorimetry (DSC).

Izod impact strength

It was measured according to ASTM D-256.

Heat Distortion Temperature

It was measured according to ASTM D648.

Example 2

An alphamethylstyrene-acrylonitrile copolymer was prepared under the same conditions as in Example 1 except that 0.03 parts by weight of an initiator was added to 100 parts by weight of the reaction mixture in the second stirred tank reactor, thereby preparing a heat resistant ABS resin. . Physical properties of the prepared alpha methyl styrene-acrylonitrile copolymer and the heat resistant ABS resin are shown in Table 1 below.

Example 3

An alphamethylstyrene-acrylonitrile copolymer was prepared under the same conditions as in Example 1 except that 0.05 parts by weight of an initiator was added to 100 parts by weight of the reaction mixture in the second stirred tank reactor, thereby preparing a heat resistant ABS resin. . Physical properties of the prepared alpha methyl styrene-acrylonitrile copolymer and the heat resistant ABS resin are shown in Table 1 below.

Example 4

An alphamethylstyrene-acrylonitrile copolymer was prepared under the same conditions as in Example 1 except that the polymerization was carried out while maintaining the temperature of the second agitator reactor at 107 ° C., thereby producing a heat resistant ABS resin. Physical properties of the prepared alpha methyl styrene-acrylonitrile copolymer and the heat resistant ABS resin are shown in Table 1 below.

Example 5

An alphamethylstyrene-acrylonitrile copolymer was prepared under the same conditions as in Example 1 except that the polymerization was carried out while maintaining the temperature of the second agitator reactor at 105 ° C., thereby producing a heat resistant ABS resin. Physical properties of the prepared alpha methyl styrene-acrylonitrile copolymer and the heat resistant ABS resin are shown in Table 1 below.

Comparative Example 1

An alphamethylstyrene-acrylonitrile copolymer was prepared under the same conditions as in Example 1 except that no initiator was added to the second stirred tank reactor, and thus a heat resistant ABS resin was prepared. Physical properties of the prepared alpha methyl styrene-acrylonitrile copolymer and the heat resistant ABS resin are shown in Table 1 below.

Comparative Example 2

An alphamethylstyrene-acrylonitrile copolymer was prepared under the same conditions as in Example 1 except that the total amount of the initiator of Example 1 was added to the first stirred tank reactor without adding an initiator to the second stirred tank reactor. A heat resistant ABS resin was prepared. Physical properties of the prepared alpha methyl styrene-acrylonitrile copolymer and the heat resistant ABS resin are shown in Table 1 below.

The physical properties of the reaction products (A) prepared in the above Examples and Comparative Examples and the resin compositions (B) prepared using these were measured and summarized as shown in Table 1 below.

TABLE 1

division Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Raw Material Mixtures and Reaction Conditions Reaction mixture composition (parts by weight) Alphamethylstyrene 65 Acrylonitrile 30 Toluene 5 1st stirred tank reactor initiator (parts by weight) 0.1 0.11 2nd stirred tank reactor initiator (parts by weight) 0.01 0.03 0.05 0.01 0.01 0 0 1st stirred vessel reactor temperature (° C) 110 ℃ Second Stirred Tank Reactor Temperature (° C) 110 110 110 107 105 110 110 Reaction product (A) Alphamethylstyrene (parts by weight) 71.8 71.6 71.5 72.1 72.5 71.9 72.2 Acrylonitrile (parts by weight) 28.2 28.4 28.5 27.9 27.5 28.1 27.8 % Conversion 59 64 70 55 51 49 53 Weight average molecular weight 100,000 95,000 92,000 105,000 112,000 90,000 85,000 Glass transition temperature (℃) 126 125 124 126 125 121 120 Melt index (g / 10 min) 11 12 12 10 8 13 14 Residual monomer (ppm) 2100 1900 1750 2500 3200 2500 2400 Oligomer 1.0 0.9 0.8 1.2 1.1 1.6 1.5 Loss of heating (% by weight) 1.2 1.0 0.6 1.8 2.6 2.1 2.0 Resin composition (B) Impact Strength (kgcm / cm) 24 26 27 23 21 20 19 Melt index (g / 10 min) 11 9 8 9 10 12 12 Heat Deflection Temperature (℃) 103 102 102 101 100 101 100

As can be seen in Table 1, compared with the embodiment, as shown in Comparative Examples 1 and 2 in which the initiator is not branched, the conversion rate is significantly lower, the molecular weight is lower, and the mechanical properties of the heat and heat resistant ABS resin are also insufficient. Could know.

Although described in detail with respect to the preferred embodiment of the present invention, those skilled in the art to which the present invention pertains, the present invention without departing from the spirit and scope of the invention defined in the appended claims Various modifications can be made. Therefore, changes in the future embodiments of the present invention will not be able to escape the technology of the present invention.

The method for producing a heat resistant copolymer according to the present invention has the effect of enabling efficient operation by not only providing a copolymer having excellent heat resistance but also increasing the conversion rate of the monomer to be supplied. In addition, by reducing the residual monomer content of the final product has the effect of producing a product of better physical properties.

By mixing the heat-resistant copolymer prepared by the production method according to the present invention as described above to the ABS resin has an effect that can be obtained a heat-resistant ABS resin composition excellent in heat resistance.

Claims (14)

Continuously supplying a reaction mixture comprising alphamethylstyrene and acrylonitrile to a first stirred tank reactor of two or more stirred tank reactor systems connected in series to produce a polymer; And supplying the resultant polymer and the unreacted mixture of the first stirred tank reactor to the stirred tank reactor after the second stirred tank reactor to continuously prepare the polymer. The method according to claim 1, wherein the polyfunctional organic peroxide initiator is branched and supplied to at least one stirred tank reactor of the first stirred tank reactor and the second stirred tank reactor after the second stirred tank reactor to polymerize. The alphamethylstyrene-acrylonitrile copolymer according to claim 1, wherein the reaction mixture comprises 50 to 75 parts by weight of alphamethylstyrene and 25 to 40 parts by weight of acrylonitrile with respect to 100 parts by weight of the reaction mixture. Manufacturing method. The method for producing an alphamethylstyrene-acrylonitrile copolymer according to claim 1, wherein the temperature of each stirred tank reactor is 100 to 130 ° C. The method of claim 1, wherein the average residence time of each reaction tank reactor of the reaction mixture is 2 hours to 4 hours. The method of claim 1, wherein the reaction mixture further comprises 0.1 to 15 parts by weight of solvent with respect to 100 parts by weight of the reaction mixture. The method of claim 5, wherein the solvent is ethylbenzene, toluene, xylene, methyl ethyl ketone or a mixture thereof. The method of claim 1, wherein the multifunctional organic peroxide initiator is 1,1-bis (tert-butyl peroxy) -2-methylcyclohexane, 1,1-bis (tert-butyl peroxy) cyclohexane, 1,1 -Bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane, 2,2-bis (tertiarybutylperoxy) butane, or 2,2-bis (4,4-dibutylbutylperoxy It is cyclohexyl) propane, The manufacturing method of the alphamethylstyrene- acrylonitrile copolymer. According to claim 1, wherein the multifunctional organic peroxide initiator is supplied to the first stirring tank reactor 0.05 to 0.5 parts by weight relative to 100 parts by weight of the reaction mixture, at least one stirring tank reactor after the second stirring tank reactor A method for producing an alphamethylstyrene-acrylonitrile copolymer, characterized in that 0.005 to 0.05 parts by weight of the reactor is supplied to 100 parts by weight of the contents of the stirred tank reactor. The product of claim 1, wherein the product of the final stirred tank reactor of the stirred tank reactor system is introduced into the volatilization tank, and the unreacted monomer and the solvent are heated at a temperature of 200 to 250 DEG C and a pressure of 50 torr or lower in the volatilized tank Vaporizing and separating the unreacted monomer and the solvent, and condensing and feeding the separated unreacted monomer and solvent to a stirred tank reactor system. 2. The reaction conversion rate according to claim 1, wherein the reaction conversion rate at the outlet of the first stirred tank reactor of the stirred tank reactor system is 25 to 35%, and the reaction conversion rate at the outlet of the final stirred tank reactor is 50 to 80%. A method for producing an alphamethylstyrene-acrylonitrile copolymer, characterized by the above-mentioned. The method of claim 1, further comprising supplying or removing heat to the reaction mixture in a heat exchanger installed at a front end of the agitator reactor system. Prepared by the method according to any one of claims 1 to 11, with respect to 100 parts by weight of the copolymer of alpha methyl styrene 68 to 75 parts by weight, acrylonitrile content of 25 to 32 parts by weight, weight average An alphamethylstyrene-acrylonitrile copolymer having a molecular weight of 90,000 to 110,000 and a glass transition temperature of 123 ° C or higher. 13. The alphamethylstyrene-acrylonitrile copolymer according to claim 12, wherein the content of residual monomer remaining in the alphamethylstyrene-acrylonitrile copolymer is 2000 ppm or less. A heat resistant ABS resin composition comprising 20 to 50 parts by weight of the alphamethylstyrene-acrylonitrile copolymer according to claim 12 and 80 to 50 parts by weight of the ABS resin.

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