KR20080035214A - Alpha methyl styrene-acrylonitrile-methylmethacrylate copolymer having excellent heat resistance and processibility, and a method of preparation thereof - Google Patents

Abstract

A method for preparing an alpha-methylstyrene-acrylonitrile-methyl methacrylate copolymer resin continuously, and an alpha-methylstyrene-acrylonitrile-methyl methacrylate copolymer resin prepared by the method are provided to improve heat resistance and processability and to enhance polymerization conversion and purity. A method for preparing an alpha-methylstyrene-acrylonitrile-methyl methacrylate copolymer resin comprises the steps of injecting a reaction mixture comprising 65-70 parts by weight of alpha-methylstyrene, 25-30 parts by weight of acrylonitrile, 5-10 parts by weight of methyl methacrylate, a solvent and an organic peroxide initiator into a polymerization device and polymerizing them by mass polymerization; and injecting the polymer solution into a volatilization bath and volatilizing the solvent to separate a polymer.

Description

Alpha methyl styrene-acrylonitrile-methyl methacrylate copolymer resin having excellent heat resistance and processability, and a method for preparing the same. {Alpha methyl styrene-acrylonitrile-methylmethacrylate copolymer having excellent heat resistance and processibility, and a method of preparation

The present invention relates to an alphamethylstyrene-acrylonitrile-methylmethacrylate copolymer resin having excellent heat resistance and processability, and a method for producing the same.

Acrylonitrile-butadiene-sterene copolymer resin (hereinafter referred to as ABS resin) is a material having excellent rigidity, impact resistance, surface gloss, and chemical resistance, and is widely used in various fields such as electric and electronic products and office equipment parts requiring such characteristics. It is used industrial material. However, since the ABS resin is low in heat resistance, there is a limit in use in parts requiring heat resistance such as automobile interior and exterior materials.

Therefore, in order to overcome this, 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 is used. A general method of introducing a monomer having excellent heat resistance is a method of adding a maleimide-based or alphamethylstyrene-based monomer having excellent heat resistance in a polymerization process, and as another method, a heat-resistant copolymer resin containing the monomer having excellent heat resistance is ABS. There is a method of mixing with resin.

As described above, the heat-resistant ABS resin manufactured by partially introducing monomers having excellent heat resistance into the composition of the ABS resin must have excellent physical properties such as heat resistance, impact strength, and stiffness, as well as decomposition and heat of the resin during processing by extrusion and injection. There should be no problem such as discoloration.

The copolymer resin having excellent heat resistance is usually prepared by copolymerizing a maleimide monomer or an alpha methyl styrene monomer with a vinyl cyanide compound such as acrylonitrile, an aromatic vinyl monomer such as styrene, or ternary copolymerization.

The maleimide-based monomer has a problem that it is difficult to control the reaction temperature because it has a very fast polymerization rate, and also monomers such as alpha methyl styrene has a very low polymerization temperature (61 ℃) polymerization rate In addition to the slow reaction time, a long reaction time is required, and the resulting polymer has a low molecular weight and easily undergoes pyrolysis.

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

The method of manufacturing the copolymer resin excellent in heat resistance using the emulsion polymerization method is known a lot. For example, U.S. Patent No. 3,010,936 and U.S. Patent No. 4,774,287 disclose heat-resistant ABS by copolymerizing a copolymer prepared by emulsion polymerization method using alphamethylstyrene, acrylonitrile, styrene monomer, or tertiary copolymer resin with ABS resin. Prepared. In addition, US Patent No. 3,367,995 prepared a heat-resistant ABS resin by the emulsion polymerization method using rubber latex, styrene, acrylonitrile, alphamethyl styrene. The above methods are methods for producing heat-resistant ABS by introducing alpha methyl styrene into the composition of the ABS resin, and have been shown to be effective in improving their heat resistance, but they also have the following problems.

First, the emulsion polymerization method is generally used to prepare a polymer resin in the process consisting of polymerization, flocculation, dehydration, drying process, water, emulsifier, flocculant, and the reaction temperature is lower than the bulk polymerization method.

Second, the emulsion polymerization method can overcome the disadvantage that the produced resin is difficult to have a high molecular weight due to the low polymerization temperature, which is a characteristic of the alpha methyl styrene in the polymerization process, but on the contrary, the reaction speed is slow and requires a long reaction time.

Third, the emulsion neutralization method requires high agglomeration temperature conditions because of the high heat resistance of the resin in the agglomeration process, resulting in high energy consumption and very difficult setting conditions.

Fourth, the emulsion neutralization method contains a small amount of impurities such as emulsifiers, flocculants, etc., which are used as a subsidiary material, in the resin, which is easily decomposed and discolored by heat when the resin is processed by extrusion or injection.

Fifth, since the emulsion polymerization method uses acrylonitrile in water having superior affinity to other monomers in water, it contains a relatively large amount of acrylonitrile in comparison with other polymerization methods to form a polymer. However, polymers containing a large amount of acrylonitrile are easily discolored by heat, and are present as red or black foreign substances that are insoluble gels that are insoluble in solvents and thus impair the appearance of the product.

Sixth, since the emulsion polymerization method does not have a recovery process for volatilizing unreacted monomers at high temperature and high vacuum like the bulk polymerization method, a large amount of residual monomer is contained in the resin, and the higher the content of the residual monomer, the lower the heat resistance.

Due to the problems of the emulsion polymerization method described above, the heat-resistant ABS resin produced using the alpha methyl styrene copolymer resin prepared by the emulsion polymerization method is the smell caused by decomposition of the resin when processing by extrusion, injection, surface sharpness of the injection molding There is a problem that the appearance physical properties such as degradation, heat discoloration, weather resistance, etc. are lowered.

US Pat. No. 4,757,109 and Japanese Laid-Open Patent Publication No. 58-206657 are methods of maleimide monomers, vinyl cyanide compound monomers, and aromatic vinyl compounds in a method other than a method for producing a heat resistant ABS resin using an alpha methyl styrene copolymer resin. A method of improving heat resistance by mixing a heat resistant resin prepared by using an emulsion polymerization method with an ABS resin is disclosed.

The above method is an effective method for producing a resin having a high heat resistance because the heat resistance greatly increases as the number of maleimide monomers in the resin increases.

However, as described above, the production method using the maleimide monomer has the problems of the resin prepared by the emulsion polymerization method, and unlike alphamethyl styrene, the reaction rate is very fast and the heat of reaction is high. There is a limit to increase the monomer, there is a problem that the polymerization process is very complicated to overcome this. In addition, the more the maleimide contained in the copolymer resin, the lower the compatibility with the contained ABS resin, there is a problem that the impact strength is lowered.

On the other hand, US Patent No. 4,874,829 has proposed a method for producing a copolymer or terpolymer by mass polymerization method using alpha methyl styrene, acrylonitrile, maleimide monomer. This method includes a large amount of highly reactive acrylonitrile in order to overcome the low polymerization conversion rate of alpha methyl styrene, and is effective in overcoming low conversion rate in preparing high heat-resistant resin containing alpha methyl styrene. . However, because the method has a very high acrylonitrile content in the reaction mixture, the resin produced in this process is not only severely discolored, but also contains a large amount of acrylonitrile, which may result in a gel-like substance which is insoluble in a solvent.

US Patent No. 4,795,780 discloses a process for preparing copolymer resins containing alphamethylstyrene and acrylonitrile by continuous bulk polymerization. This method is also to overcome the low conversion rate when preparing the copolymer resin containing alpha methyl styrene, and the copolymerization reaction is carried out by continuously adding alpha methyl styrene and acrylonitrile monomer to the reactor in which two stirred tank reactors are connected in series. In particular, it was suggested that a low conversion rate can be overcome by applying a condensate condensed into the first reactor after evaporation in the second reactor. However, this method uses AIBN as an initiator, which is not effective in increasing conversion and molecular weight in the reaction of copolymerizing alphamethylstyrene and acrylonitrile. In addition, acrylonitrile has a much lower boiling point than alphamethylstyrene, so most of the components of the material evaporated in the second reactor are acrylonitrile, so if this condensate is returned to the first reactor, uneven mixing may occur and Compositional differences in monomers may occur. That is, the heterogeneous mixing and the composition difference of the reactants result in a wide distribution of the composition of the resulting polymer resin, resulting in low physical properties.

In preparing the copolymer resin containing alpha methyl styrene, the above problems are caused by the properties of the material possessed by the alpha methyl styrene monomer. There is a limit.

Accordingly, it is an object of the present invention to provide an alphamethylstyrene-acrylonitrile-methylmethacrylate copolymer resin having excellent heat resistance and processability, and a method for producing the same.

Still another object of the present invention is to provide a method for preparing a high purity alphamethylstyrene-acrylonitrile-methyl methacrylate copolymer resin free from impurities such as emulsifiers and flocculants because of the bulk polymerization method.

The present invention to achieve the above object,

a) 65 to 70 parts by weight of alphamethylstyrene;

Ii) 25 to 30 parts by weight of acrylonitrile;

Iii) 5 to 10 parts by weight of methyl methacrylate;

Iii) a solvent; And

Iii) an organic peroxide initiator;

Injecting the reaction mixture comprising a into a polymerization apparatus and bulk polymerization; And

b) injecting the polymer reaction solution of step a) into the volatilization, and separating the polymer by volatilizing the unreacted monomer and the solvent;

It provides a manufacturing method by a continuous process of alpha methyl styrene-acrylonitrile-methyl methacrylate copolymer resin comprising a, excellent in heat resistance and processability.

The present invention also provides an alphamethylstyrene-acrylonitrile-methyl methacrylate copolymer resin having a high glass transition temperature of 121.5 ° C. or more and a flow index of 9.9 (g / 10min) or more, which is excellent in heat resistance and processability. .

Hereinafter, the present invention will be described in more detail.

In order to prepare an alphamethylstyrene-acrylonitrile-methylmethacrylate copolymer resin having excellent heat resistance and processability according to the present invention, first, a) iii) 65 to 70 parts by weight of alphamethylstyrene ii) 25 to 30 parts by weight of acrylonitrile Iv) 5 to 10 parts by weight of methyl methacrylate iii) a reaction mixture comprising a solvent and iii) an organic peroxide initiator is added to the polymerization apparatus and bulk polymerization is carried out.

In the high heat resistant resin containing alphamethyl styrene, the content and structure of the alphamethylstyrene monomer constituting the polymer chain are very important. If the content of the alpha methyl styrene monomer in the injected monomer is a certain level or more, a structure in which three or more alpha methyl styrenes, which are structures that are easily decomposed by heat, is rapidly formed in the chain of the resulting resin. On the contrary, if the alpha methyl styrene monomer portion is below a certain level, the heat resistance is lowered and the degree of turning yellow when heated is severe. In addition, a gel polymer which is insoluble in a solvent containing a large amount of acrylonitrile is formed. The gel polymer is very weak to heat, and when heated, the gel polymer acts as a red or black foreign material, thereby damaging the appearance of the product. Therefore, in the preparation of alphamethyl styrene copolymer resin by the bulk polymerization method of the present invention, in order to obtain a copolymer resin having excellent heat resistance, heat discoloration, thermal decomposition and gel formation, 65 to 70 parts by weight of alpha methyl styrene, acrylonitrile 25 to 30 It is preferable to add the monomer by weight and 5 to 10 parts by weight of methyl methacrylate, and the alphamethylstyrene copolymer resin prepared therefrom is 60 to 68 parts by weight of the alphamethylstyrene monomer portion and 27 to 32 acrylonitrile content. By weight, methyl methacrylate content of 5 to 8 parts by weight.

The solvent used in the present invention is used to control the reaction viscosity and reaction temperature, although ethylbenzene, toluene, xylene, methyl ethyl ketone, and the like can be used, but the boiling point of alpha methyl styrene is a low boiling point solvent such as toluene and methyl Ethyl ketone or mixtures thereof are preferred. It is preferable that the addition amount of a solvent is 5-15 weight part with respect to 100 weight part of monomer total amounts (total amount of alphamethylstyrene, acrylonitrile, and methyl methacrylate).

As the organic peroxide initiator, an organic peroxide initiator which is commonly used may be used, and preferably an organic peroxide having a polyfunctional group may be used. The organic peroxide having the multifunctional group has a low conversion temperature and a molecular weight due to the low polymerization temperature of alphamethylstyrene. This very low feature allows overcoming problems that are not easy for commercial production.

Organic peroxides having polyfunctional groups used in the present invention include 1,1-bis (tertarybutylperoxy) -2-methylcyclohexane, 1,1-bis (tertarybutylperoxy) cyclohexane, 1,1- Bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane, 2,2-bis (tertiarybutylperoxy) butane, 2,2-bis (4,4-dibutylbutyloxyoxyhexyl Propane is preferred.

The multifunctional group-containing organic peroxide initiator is preferably included in 0.05 to 0.3 parts by weight based on 100 parts by weight of the total amount of the monomer added in step a). If the content is less than 0.05 parts by weight or more than 0.3 parts by weight, there is a problem that the conversion to a heat resistant resin and the molecular weight of the heat resistant resin can be lowered.

The polymerization of step a) may be performed under conditions of a reaction temperature of 100 to 130 ° C. and a residence time of 6 to 8 hours in the reactor.

The polymerization apparatus used in the present invention is not particularly limited, but a continuous polymerization apparatus in which two or more stirred tank reactors are connected in series is preferable. In this case, the reactor is not particularly limited, but the first reactor is preferably a stirring tank having a heat exchanger attached to the front end of the reactor, and the second or more reactor is preferably an evaporative stirring tank reactor including a stirring tank, a storage tank, a condenser, and a pressure control plate.

Since alpha methyl styrene also has a low heat of reaction, the amount of heat to be removed in the first reactor may be very low or may need to be supplied with heat. Therefore, although the shape of the reactor may be any, it is preferable that a heat exchanger is installed at the front end of the reactor for uniform temperature control.

In the second or more reactor, it is preferable that the temperature of the reactor is controlled by refluxing a portion of the unreacted monomer or solvent evaporated through the pressure control of the reactor and passing it back to the reactor while passing through the condenser and the reservoir.

Specifically, in the case of continuously producing the alphamethylstyrene copolymer resin by the bulk polymerization method by using a continuous polymerization apparatus in which two or more stirred tank reactors are connected in series, the raw material mixture is continuously added to the first reactor, and polymerized. The first unpolymerized monomer is polymerized while continuously transferring the first polymerized reactant to a second reactor connected to the first reactor.

In the first reactor, the reaction mixture including the monomer mixture, the multifunctional group-containing initiator mixture, and the reaction solvent is kept at a temperature of 100 to 130 ° C. for 4 to 6 hours to firstly polymerize the polymerization conversion to 20% to 45%. The first polymerized reaction product is continuously transferred to a second reactor connected to the first reactor. The transferred reaction product is allowed to remain in the second reactor for 2 to 4 hours at a temperature of 100 to 130 ° C. to polymerize such that the polymerization conversion rate is 40 to 60%.

Next, b) the polymer reaction solution of step a) is added to the volatilization, and the step of separating the polymer by volatilizing the unreacted monomer and the solvent.

This step may be carried out in a conventional volatilization and separation process in a conventional volatilization, for example, the reaction solution (polymer reaction solution) polymerized and discharged in a continuous polymerization apparatus is a temperature of 100 to 200 ℃ and 500 to 650torr or less The reaction solution was introduced into a first volatilization tank having a heat exchanger to maintain a vacuum pressure of and then the reaction solution flowed out of the first volatilization tank has a temperature of 200 to 250 ° C. and a vacuum pressure of 50 torr or less, preferably 20 to 30 torr. Into the second volatilization tank attached to the heat exchanger to maintain, volatilize the unreacted monomer and the solvent, and then condensed again as raw materials, the polymer is processed into a pellet form while passing through the feed pump extruder to be carried out Can be. Residual monomers in this process can maintain levels below 3000 ppm.

Next, if necessary, the method may further include the c) step of condensing the unreacted monomer of step b) and the solvent and re-feeding the raw material of step a).

The alphamethylstyrene-acrylonitrile-methyl methacrylate copolymer resin prepared by the above method has a glass transition temperature of 121.5 ° C. or more, a flow index of 9.9 (g / 10 min) or more, and has excellent heat resistance and processability. .

The present invention will be described in more detail with reference to the following examples and comparative examples. However, an Example is for illustrating this invention and is not limited only to these.

Example 1

1,1-initiator containing a total of 100 parts by weight of a monomer comprising 65 parts by weight of alpha-methylstyrene and 30 parts by weight of acrylonitrile and 5 parts by weight of methyl methacrylate in a reactor in which a stirring vessel is connected in series. 0.1 parts by weight of bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane and 5 parts by weight of toluene were continuously added to the first reactor and the second reactor with a stirrer. The reaction temperature and pressure of the first and the second reactor was 110 ℃, while maintaining the total residence time of 8 hours, the bulk polymerization was carried out to convert the monomers introduced into the polymer.

The unreacted monomer and the solvent were removed from the polymerization reactor passing through the second reactor while maintaining the temperature of 150 ° C. and the vacuum pressure of 550 torr in the first volatilization tank to which the heat exchanger was attached, and the temperature of 250 ° C. in the second volatilization tank. After further removing the unreacted monomer and solvent while maintaining the vacuum pressure condition of 30 torr, the polymer was processed into a pellet form through an exhaust pump extruder to prepare an alphamethylstyrene-acrylonitrile-methyl methacrylate copolymer resin.

The molecular weight, glass transition temperature, and flow index of the obtained copolymer resin pellets were measured.

The molecular weight was measured by gel chromatography, flow index was measured according to ASTM D-1238 (220 ℃, 10Kg), the glass transition temperature (Tg) was measured using a differential scanning calorimeter (DSC). , The measurement results are shown in Table 1 below.

EXAMPLES 2-3, COMPARATIVE EXAMPLES 1-2

As shown in Table 1 below, except that only the monomer content and type of Example 1 is different, alphamethylstyrene-acrylonitrile-methylmethacrylate copolymer resin (or alpha) in the same manner as in Example 1 Methyl styrene-acrylonitrile copolymer resin) was prepared, and measured physical properties of the molecular weight, glass transition temperature, and flow index of the prepared copolymer resin pellets are shown in Table 1 below.

As shown in Table 1, Examples 1 to 3, the polymerization conversion rate, glass transition temperature (heat resistance) of the prepared alpha methyl styrene-acrylonitrile-methyl methacrylate copolymer resin compared to Comparative Examples 1 and 2 , Physical properties such as flow index (processability) were excellent overall.

The alphamethylstyrene-acrylonitrile-methylmethacrylate copolymer resin according to the present invention has the advantage of excellent heat resistance and processability, and the manufacturing method according to the present invention has a high polymerization conversion rate and uses a bulk polymerization method, so that an emulsifier and a flocculant are used. There is an advantage in that a high purity alphamethylstyrene-acrylonitrile-methylmethacrylate copolymer resin free from impurities such as the like can be prepared.

Claims (12)

The present invention to achieve the above object, a) 65 to 70 parts by weight of alphamethylstyrene; Ii) 25 to 30 parts by weight of acrylonitrile; Iii) 5 to 10 parts by weight of methyl methacrylate; Iii) a solvent; And Iii) an organic peroxide initiator; Injecting the reaction mixture comprising a into a polymerization apparatus and bulk polymerization; And b) injecting the polymer reaction solution of step a) into the volatilization, and separating the polymer by volatilizing the unreacted monomer and the solvent; The manufacturing method by the continuous process of alphamethylstyrene-acrylonitrile-methylmethacrylate copolymer resin which is excellent in heat resistance and processability which consist of including. The method of claim 1, The non-reacted monomer of step b), and c) step of condensing the solvent back to the raw material of step a), characterized in that it further comprises alphamethylstyrene-acrylonitrile- excellent heat resistance and processability The manufacturing method by the continuous process of methyl methacrylate copolymer resin. The method according to claim 1 or 2, The polymerization apparatus is a continuous polymerization apparatus in which two or more stirred tank reactors are connected in series. The first reactor is a stirred tank reactor having a heat exchanger attached to the front of the reactor, and the second or more reactors include a stirring tank, a storage tank, a condenser, and a pressure control plate. It is an evaporation type stirred tank reactor, The manufacturing method by the continuous process of alphamethylstyrene-acrylonitrile-methylmethacrylate copolymer resin excellent in heat resistance and workability. The method of claim 3, wherein The polymerization of step a) is carried out in the first reactor to the reaction temperature of 100 to 130 ℃, residence time of 4 to 6 hours of polymerization to convert 20 to 45% by weight of the introduced monomer into the polymer, and then reacted in the second or more reactors Alphamethylstyrene-acrylonitrile-methyl meta excellent in heat resistance and processability, characterized in that 40 to 60% by weight of the monomers polymerized by polymerization under conditions of temperature 100 to 130 ° C. and residence time 2 to 4 hours are converted to polymers. The manufacturing method by the continuous process of a acrylate copolymer resin. The method of claim 3, wherein The reactor of step a) is a stirred tank reactor in which the first reactor has a heat exchanger attached to the front end of the reactor, and the second or more reactors include a reactor, a condenser, a reservoir, and a pressure control plate, and the unreacted monomer is evaporated in the reaction solution. And then condensed in a condenser, stored in a storage tank, and then re-introduced into the reactor to control the reaction temperature, and is characterized in that it is an alpha-methylstyrene-acrylonitrile-methylmethacrylate having excellent heat resistance and processability. The manufacturing method by the continuous process of a acrylate copolymer resin. The method according to claim 1 or 2, The polymerization of step a) is carried out under the conditions of the reaction temperature of 100 to 130 ℃, the residence time of the reaction mixture in the reactor of 6 to 8 hours, alphamethylstyrene-acrylonitrile-methylmethacryl excellent in heat resistance and processability The manufacturing method by the continuous process of a rate copolymer resin. The method according to claim 1 or 2, In step b), the polymer reaction solution of step a) is introduced into a first volatilization tank equipped with a heat exchanger maintaining a temperature of 100 to 200 ° C. and a vacuum pressure of 500 to 650 torr or less, and then flowed out of the first volatilization tank. The reaction solution is introduced into a second volatilization tank equipped with a heat exchanger maintaining a temperature of 200 to 250 ° C. and a vacuum pressure of 50 torr or less, and is characterized in that alphamethylstyrene-acrylonitrile-methylmethacrylate having excellent heat resistance and processability. The manufacturing method by the continuous process of a acrylate copolymer resin. The method according to claim 1 or 2, The a) step solvent is selected from toluene, methyl ethyl ketone and mixtures thereof, and the addition amount is 5 to 15 parts by weight based on 100 parts by weight of the total monomer, alphamethylstyrene-acrylic having excellent heat resistance and processability The manufacturing method by the continuous process of a nitrile-methyl methacrylate copolymer resin. The method according to claim 1 or 2, In step a), the multifunctional group-containing organic peroxide is 1,1-bis (tertiarybutylperoxy) -2-methylcyclohexane, 1,1-bis (tertiarybutylperoxy) cyclohexane, 1,1-bis ( Tertiarybutylperoxy) -3,3,5-trimethylcyclohexane, 2,2-bis (tertiarybutylperoxy) butane, 2,2-bis (4,4-dibutylbutyloxyoxyhexyl) propane It is selected from the group consisting of, the addition amount is 0.05 to 0.3 parts by weight based on 100 parts by weight of the total monomer, by the continuous process of alphamethylstyrene-acrylonitrile-methyl methacrylate copolymer resin excellent in heat resistance and processability Manufacturing method. The alphamethylstyrene-acrylonitrile-methylmethacrylate copolymer resin prepared according to claim 1 or 2 is characterized in that the residual monomer content is 3000 ppm or less. The manufacturing method by the continuous process of methyl methacrylate copolymer resin. The alpha methyl styrene content prepared by the method according to claim 1 or 2 is 60 to 68 parts by weight, the acrylonitrile content is 27 to 32 parts by weight, and the methyl methacrylate content is 5 to 8 parts by weight. , Alphamethylstyrene-acrylonitrile-methylmethacrylate copolymer resin having excellent heat resistance and processability. An alphamethylstyrene-acrylonitrile-methyl methacrylate copolymer resin having a glass transition temperature of 121.5 ° C. or more and a flow index of 9.9 (g / 10 min) or more prepared by the method of claim 1 or 2.