KR100828715B1 - Method of preparing copolymer resin of ?-methyl styrene and vinyl cyan compounds having improved heat-resistance - Google Patents

Abstract

The present invention (a) 100 parts by weight of a monomer mixture comprising an α-methylstyrene monomer and a vinyl cyan compound; 0.05 to 0.3 part by weight of a multifunctional group-containing initiator; And performing polymerization while continuously adding 5 to 15 parts by weight of the reaction solvent to the reactor to polymerize such that the polymerization conversion rate is 50 to 70%. And (b) provides a method for producing a heat-resistant resin comprising the step of separating the polymer by volatilizing the unreacted monomer and solvent in the volatilization of the resulting polymerization product.

The heat resistant resin prepared by the production method according to the present invention has a high polymerization conversion rate and more excellent heat resistance while maintaining the general physical properties of the conventional heat resistant resin.

α-methylstyrene, vinyl cyan compound, polyfunctional group-containing initiator, bifunctional group-containing initiator, four or more functional group-containing initiators, heat resistant resins, bulk polymerization, glass transition temperature

Description

Method of preparing copolymer resin of α-methyl styrene and vinyl cyan compounds having improved heat-resistance

The present invention relates to a method for producing a copolymerized heat resistant resin of α-methyl styrene and vinyl cyan compound, and more particularly, to α-methyl styrene having high polymerization conversion rate and improved heat resistance while maintaining physical properties similar to those of conventional heat resistant resins. A method for producing a copolymerized heat resistant resin of a vinyl cyan compound.

Acrylonitrile-butadiene-styrene copolymer resin (hereinafter referred to as "ABS resin") has excellent stiffness, impact resistance, surface gloss, chemical resistance, and is widely used in various fields such as electrical and electronic products, office equipment housing, automobile parts, etc. In particular, research on a method of improving the heat resistance of the ABS resin to be used in parts that require heat resistance, such as automotive interior, exterior materials are continuously underway.

One of them is a method of adding a maleimide-based or α-methylstyrene-based monomer having excellent heat resistance to the polymerization process or kneading a heat resistant copolymer resin containing the monomer having excellent heat resistance with an ABS resin.

Heat-resistant ABS resin produced by the above method should be excellent in general physical properties such as impact strength, rigidity as well as heat resistance, there should be no problems such as decomposition and thermal discoloration of the resin in the processing process, such as extrusion and injection.

α-methylstyrene generally has a very low polymerization temperature (61 ° C.), and thus has a low polymerization rate, and thus needs to be reacted for a long time, and the resulting polymer has a low molecular weight and easily undergoes pyrolysis.

Therefore, in the conventional method, it is common to prepare a heat resistant ABS resin by an emulsion polymerization method using a batch process, which is mainly easy to control the polymerization temperature and easily control the reaction time. Such a method is well described in US Patent No. 3,010,936, US Patent No. 4,774,287, US Patent No. 3,367,995, and the like.

However, when the emulsion polymerization method is used, the reaction temperature is low, a long reaction time is required, a high aggregation temperature condition is required, and the resin may be discolored during the aggregation process, and impurities such as an emulsifier and a flocculant are included in the resin. In processing processes such as extrusion and injection, there is a problem in that it is easily decomposed by heat, and thermal discoloration may occur.

In addition, the above method does not go through the process of recovering the unreacted monomer, the heat resistance may be reduced due to the monomer remaining in the resin, thermal discoloration easily occurs due to the unreacted acrylonitrile remaining in the resin, insoluble in the resin Due to the presence of a gel (gel) there is a problem that the appearance of the product, such as red spots, black spots may not be good.

In order to overcome this problem, U.S. Patent No. 4,874,829 discloses a method of preparing a copolymer or terpolymer by bulk polymerizing α-methylstyrene, acrylonitrile and maleimide monomers, which is α-methyl. In order to overcome the low polymerization conversion of styrene, a method using a large amount of acrylonitrile having excellent reactivity is used. However, this method has a problem that the copolymer resin produced is severely discolored because the content of acrylonitrile in the reaction mixture is very high, and may contain a large amount of insoluble gel.

In addition, US Pat. No. 4,795,780 discloses a process for producing a copolymer resin containing α-methylstyrene and acrylonitrile by continuous bulk polymerization. In order to overcome the low polymerization conversion rate of α-methylstyrene, this method involves copolymerizing α-methylstyrene and acrylonitrile in a continuous reactor in which two stirred tank reactors are connected in series. After the condenser was passed through the condensed condensate to the first reactor was applied. However, the method is a copolymerization reaction using azobis-isobutyronitrile (AIBN) as an initiator during the copolymerization reaction, and the conversion and molecular weight are not large, and the material evaporated in the second reactor is mostly acrylonitrile. Therefore, when it is re-introduced into the first reactor, heterogeneous mixing of monomers may occur, and there is a problem that a composition difference of polymers may occur in two reactors.

The present invention is to solve the problems of the prior art as described above, the first technical problem of the present invention while maintaining the general physical properties of the conventional heat-resistant resin high α-methylstyrene and vinyl cyan compound having a higher exchange rate before polymerization and more heat resistance It is to provide a method for producing a copolymerized heat resistant resin.

The second technical problem of the present invention is to provide a copolymerization heat resistant resin of α-methylstyrene and vinyl cyan compound prepared by the above method.

The above and other objects of the present invention can be achieved by the present invention described below.

The present invention to achieve the first technical problem

(a) 100% by weight of a monomer mixture comprising an α-methylstyrene monomer and a vinyl cyan compound, 0.05 to 0.3 parts by weight of a polyfunctional initiator, and 5 to 15 parts by weight of a reaction solvent were subjected to polymerization while the polymerization was carried out continuously to give a polymerization conversion rate. Polymerizing such that 50 to 70%; And

(b) providing a method for producing a heat resistant resin comprising separating the polymer by volatilizing the unreacted monomer and solvent in the volatilization of the resulting polymerization product.

In order to achieve the second technical problem, the present invention provides a copolymerization heat resistant resin of α-methylstyrene and vinyl cyan compound prepared by the above production method.

Copolymerized heat-resistant resin of α-methylstyrene and vinyl cyan compound prepared by the production method according to the present invention is excellent in mechanical properties such as strength, fluidity, high polymerization conversion, in particular high glass transition temperature compared to conventional heat-resistant resin It has excellent heat resistance.

Hereinafter, a method for producing a copolymerized heat resistant resin of α-methylstyrene and a vinyl cyan compound according to the present invention will be described in more detail.

Method for producing a copolymerization heat-resistant resin of the α-methylstyrene and vinyl cyan compound according to the present invention comprises (a) 100 parts by weight of a monomer mixture comprising an α-methylstyrene monomer and a vinyl cyan compound; 0.05 to 0.3 part by weight of a multifunctional group-containing initiator; And performing polymerization while continuously introducing 5 to 15 parts by weight of the reaction solvent into a reactor having at least one reaction tank (polymerization step) to achieve a polymerization conversion rate of 50 to 70%. And

(b) separating the polymer by volatilizing the resulting polymerization product in a volatilization of unreacted monomer and solvent (polymer separation step).

Hereinafter, the separation in each step will be described in more detail.

(a) polymerization step

In the method for preparing a heat resistant resin according to the present invention, the monomer mixture used in the polymerization step includes α-methylstyrene monomer and vinyl cyan compound, wherein the content of α-methylstyrene monomer is based on the total weight of the total monomer mixture. It is preferable that it is 60 to 75 weight%, More preferably, it is 65 to 75 weight%. If the content of the α-methylstyrene monomer is less than 60% by weight, the heat resistance is low and yellowing is easy upon heating. If the content of the α-methylstyrene monomer is more than 75% by weight, three or more α-methylstyrenes are continuously bonded to the chain of the heat-resistant resin. There is a problem in that a structure can be produced, which is easily decomposed by heat, which is undesirable.

The vinyl cyan compound in the monomer mixture is preferably acrylonitrile, methacrylonitrile or ethacrylonitrile, more preferably acrylonitrile. The content of the vinyl cyan compound is preferably 25 to 40% by weight based on the total weight of the monomer mixture. If the content of the vinyl cyan compound is less than 25% by weight, there is a problem that the conversion and molecular weight is lowered. If the content of the vinyl cyan compound exceeds 40% by weight, an insoluble gel is formed by including a large amount of the vinyl cyan compound in the resin, thereby deteriorating appearance of the resin. It is not preferable because it is easy.

In this invention, it is preferable that the said polyfunctional group containing initiator contains a bifunctional group containing initiator and 4 or more functional group containing initiator. The inventors of the present invention have found that when a mixed ratio of an initiator containing a bifunctional group and an initiator containing four or more functional groups is mixed at a predetermined ratio, the conversion rate of polymerization is increased and the heat resistance is higher than that of each initiator alone. Increased. In the present invention, since the four or more functional group-containing initiators make a structure including a large number of branches, a resin having a high molecular weight can be formed, thereby increasing the heat resistance of the resin composition prepared using the same.

In the present invention, the bifunctional group-containing initiator is 1,1-bis (t-butylperoxy) -2-methylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t -Butyl peroxy) -3,3,5-trimethylcyclohexane or 2,2-bis (t-butylperoxy) butane.

Further, in the present invention, the four or more functional group-containing initiators include 2,2-bis (4,4-di (t-butylperoxy) cyclohexyl) propane, tri (t-butylperoxy) triazine, tri (t -Butyl peroxy) trimelliate, polyether poly-t-butylperoxy carbonate, t-butylperoxy methyl fumarate or t-butylperoxy ethylfumarate.

In the present invention, the mixing ratio of the bifunctional group-containing initiator and the 4 or more functional group-containing initiator is preferably a weight ratio of 4: 1 to 3: 2 of the bifunctional group-containing initiator: 4 or more functional group-containing initiator. When the ratio of the bifunctional group-containing initiator: 4 or more functional group-containing initiator is less than 4: 1 weight ratio, the effect of increasing the molecular weight and heat resistance is insignificant, and when the ratio is more than 3: 2 weight ratio, the polymerization conversion is decreased, which is not preferable.

In the method for producing a heat resistant resin according to the present invention, the content of the multifunctional initiator is preferably 0.05 to 0.3 parts by weight, more preferably 0.1 to 100 parts by weight of the monomer mixture containing the α-methylstyrene and vinyl cyan compound. To 0.2 part by weight. When the content of the initiator mixture is less than 0.05 parts by weight, the polymerization conversion rate is low, and when it exceeds 0.3 parts by weight, the molecular weight is low, which is not preferable.

In the method for preparing a heat resistant resin according to the present invention, the reaction solvent is preferably ethylbenzene, toluene, xylene or methyl ethyl ketone, more preferably toluene or methyl ethyl ketone. The content of the reaction solvent is preferably 5 to 15 parts by weight based on 100 parts by weight of the monomer mixture. If the content of the reaction solvent is less than 5 parts by weight, there is a problem that the viscosity may increase rapidly as the reaction proceeds, and if it exceeds 15 parts by weight, there is a problem that the conversion may be lowered, which is not preferable.

In the present invention, the polymerization of the heat resistant resin is carried out by bulk polymerization or dissolution by adding a monomer mixture comprising the α-methylstyrene and a vinyl cyan compound, the polyfunctional initiator mixture and the reaction solvent into a continuous reactor in which one or more reactors are connected in series. It can manufacture continuously with the copolymerization resin of (alpha) -methylstyrene and a vinyl cyan compound by a liquid polymerization method. The polymerization conversion rate of the monomer charged in the present invention is preferably 50 to 70%. If the polymerization conversion rate is less than 50%, the content of the unreacted monomer is high, the productivity is low, and the recovery time takes a long time, and if the polymerization conversion rate is more than 70%, the process conditions are severe and the control of the reaction is severe. It is unfavorable because it is difficult and has a problem of increasing gel formation.

Hereinafter, the polymerization process will be described in more detail.

In the first reactor, the reaction mixture including the monomer mixture, the multifunctional group-containing initiator mixture, and the reaction solvent is kept for 4 to 6 hours at a temperature of 100 to 130 ° C. to firstly polymerize the polymerization conversion to 40 to 55%. The primary 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 50 to 70%.

Although the polymerization process of the heat-resistant resin according to the present invention has been described as an example of polymerization using two reaction tanks, the case of continuous polymerization using only one reaction tank or continuous polymerization using three or more reaction tanks is also described. Without departing from the scope of the invention .

Using the above polymerization method, a polymerization product having a polymerization conversion rate of 50 to 70% can be obtained.

(b) polymer separation step

The polymerization product polymerized through each reaction tank is then introduced into a first volatilization tank having a heat exchanger attached thereto and maintaining a temperature of 100 to 150 ° C. and a vacuum pressure of 550 to 650 torr to volatilize the unreacted monomer and the solvent.

Then, α-methylstyrene and vinyl cyan from which the unreacted monomer and the reaction solvent are removed by further volatilizing the unreacted monomer and the solvent by introducing into a second volatilization tank maintaining a temperature of 200 to 250 ° C. and a vacuum pressure of 10 to 40 torr. A copolymer of the compound is obtained.

In the present invention, the unreacted monomer and the reaction solvent volatilized in the polymer separation step may be recovered by condensation and then re-injected into the polymerization step of (a).

The copolymer obtained above may then be processed while passing through a transfer pump and an extruder to produce pellets.

The present invention provides a copolymerization heat resistant resin of α-methylstyrene and vinyl cyan compound prepared through the polymerization step (a) and the polymer separation step (b). It is preferable that the said heat resistant resin has a glass transition temperature (Tg) of 124 degreeC or more.

Copolymerization heat-resistant resin of α-methylstyrene and vinyl cyan compound prepared by the production method according to the present invention has the advantage of high polymerization conversion rate, more excellent heat resistance while maintaining the physical properties of the conventional heat-resistant resin.

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

100 parts by weight of a monomer mixture comprising 70% by weight of α-methylstyrene and 30% by weight of acrylonitrile, 1,1-bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane which is a bifunctional initiator 0.1 parts by weight, 0.025 parts by weight of 2,2-bis (4,4-di (t-butylperoxy) cyclohexyl) propane and 4 parts by weight of toluene, which are four functional group-containing initiators, were continuously added to the first reactor with a stirrer. The polymerization was carried out. That is, the temperature of the first reactor and the second reactor was set to 113 ° C. and 115 ° C., respectively, and the polymerization was carried out so that 50 to 70% of the introduced monomers were converted into a polymer while maintaining the residence time for a total of 8 hours. In this embodiment, the 1,1-bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane was used as having 90% purity, and the 2,2-bis (4,4-di (t) Butyl peroxy) cyclohexyl) propane was used having a 20% purity.

The polymerized polymerization product is removed from the unreacted monomer and the solvent while maintaining a temperature of 150 ° C. and a vacuum pressure of 550 torr in a first volatilization tank to which a heat exchanger is attached, and at a temperature of 250 ° C. and 30 torr in a second volatilization tank. After further removing the unreacted monomer and solvent while maintaining the vacuum pressure, the polymer was processed into pellets through a transfer pump and an extruder to obtain a copolymerized heat resistant resin of? -Methylstyrene and acrylonitrile.

Example  2

0.08 part by weight of 1,1-bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane as the difunctional group-containing initiator, and 2,2-bis (4,4-di (t) as the four functional group-containing initiators Co-heat-resistant resin of α-methylstyrene and acrylonitrile was prepared in the same manner as in Example 1 using 0.045 part by weight of -butylperoxy) cyclohexyl) propane.

Example  3

A copolymerization heat resistant resin of α-methylstyrene and acrylonitrile was prepared in the same manner as in Example 1 using 100 parts by weight of a monomer mixture including 75 wt% of α-methylstyrene and 25 wt% of acrylonitrile.

Comparative example  One

Α-methylstyrene was prepared in the same manner as in Example 1 except that only 0.125 parts by weight of 1,1-bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane, which was a bifunctional group-containing initiator, was used. And copolymerized heat resistant resins of acrylonitrile.

Comparative example  2

Α-methylstyrene was prepared in the same manner as in Example 2 except that only 0.125 parts by weight of 1,1-bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane, which was a bifunctional group-containing initiator, was used. And copolymerized heat resistant resins of acrylonitrile.

Comparative example  3

     0.06 parts by weight of 1,1-bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane as a bifunctional group-containing initiator and 2,2-bis (4,4-di as a initiator A copolymerized heat resistant resin of α-methylstyrene and acrylonitrile was prepared in the same manner as in Example 1 except that 0.06 parts by weight of (t-butylperoxy) cyclohexyl) propane was used.

The conversion rate, weight average molecular weight, glass transition temperature, and flow index of the copolymerized heat resistant resin of α-methylstyrene and acrylonitrile prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were measured by the following method, and the results Is shown in Table 1.

(Performance evaluation)

Conversion rate

Conversion rate = (weight of monomer mixture-weight of unreacted monomer mixture) / (weight of monomer mixture) X 100

Weight average molecular weight (g / mol )

The pellets of the copolymerized heat-resistant resin thus obtained were measured by using GPC (Gel permeation chromatography, Breeze, Waters). Pellets were prepared in 20 ml of THF at a concentration of 0.02 g and measured by filtration with a filter of 0.45 u m. The measurement conditions at this time were fixed at an injection time of 25 minutes, an injection count once, and a column temperature of 40 ° C.

Glass transition temperature Tg , ℃)

The copolymerized heat resistant resin pellet was heated to 150 ° C. on DCS (Differential scanning calorimetry, TA company Q10), cooled to 30 ° C. to remove the thermal history, and then heated at a rate of 10 ° C./min to measure the glass transition temperature. It was.

Flow index (g / 10 min, 220 ℃, 10 kg)

It measured according to ASTM D1238.

division Example Comparative example One 2 3 One 2 3 Monomer α-methylstyrene 70 70 75 70 75 70 Acrylonitrile 30 30 25 30 25 30 2 functional group initiator 1,1-bis (tertiary-butylperoxy) -3,3,5-trimethylcyclohexane 0.1 0.08 0.1 0.125 0.125 0.06 4-functional group initiator 2,2-bis (4,4-di (t-butylperoxy) cyclohexyl) propane 0.025 0.045 0.025 - - 0.06 Reaction solvent toluene 5 5 5 5 5 5 % Conversion 65 63 60 58 56 50 Properties Weight average molecular weight (g / mol) 10.2 million 10.6 million 9.6 million 9.7 million 9.0 million 11.7 million Glass transition temperature (℃) 125 126 124 122 120 123 Flow index (g / 10 min) 9.1 8.6 9.9 9.8 12.2 7.2

As can be seen from the results of Table 1, the conversion rate compared to Comparative Example 1 having the same monomer composition for Examples 1 to 2, in which the bifunctional group-containing initiator and the four or more functional group-containing initiators were mixed as an initiator according to the present invention. This is about 7% high, and it can be seen that the glass transition temperature is also particularly high 3 to 4 ℃.

In addition, in the case of Example 3 according to the present invention, it can be seen that the conversion rate is about 4% higher than that of Comparative Example 2 having the same composition, and the glass transition temperature is increased by about 4 ° C.

In addition, even when both the bifunctional group-containing initiator and four or more functional groups are used from the results of Comparative Example 3, when used outside the mixing ratio according to the present invention, for example, when used in a mixing ratio of 1: 1 as in Comparative Example 3 The improvement effect is not large, and in particular, the conversion rate was confirmed that the problem is very small.

The copolymerization heat resistant resin of the α-methylstyrene monomer and the vinyl cyan compound prepared by the production method according to the present invention has a high polymerization conversion rate, a relatively high weight average molecular weight, and particularly excellent heat resistance while maintaining the general physical properties of the conventional heat resistant resin. Has

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) 100% by weight of a monomer mixture comprising an α-methylstyrene monomer and a vinyl cyan compound, 0.05 to 0.3 parts by weight of a polyfunctional initiator, and 5 to 15 parts by weight of a reaction solvent were subjected to polymerization while the polymerization was carried out continuously to give a polymerization conversion rate. Polymerizing such that 50 to 70%; And (b) isolating the polymer by volatilizing the resulting polymerization product in an unreacted monomer and a solvent in a volatilization tank Method for producing a heat resistant resin comprising a. The method of claim 1, The monomer mixture is 60 to 75% by weight of an α-methylstyrene monomer; And 25 to 40% by weight of a vinyl cyan compound. The method of claim 1, The vinyl cyan compound is acrylonitrile, methacrylonitrile or ethacrylonitrile. The method of claim 1, The said polyfunctional group containing initiator contains a bifunctional group containing initiator and four or more functional group containing initiators, The manufacturing method of the heat resistant resin characterized by the above-mentioned. The method of claim 4, wherein The bifunctional group-containing initiator is 1,1-bis (t-butylperoxy) -2-methylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylper Oxy) -3,3,5-trimethylcyclohexane or 2,2-bis (t-butylperoxy) butane. The method of claim 4, wherein The four or more functional group-containing initiators are 2,2-bis (4,4-di (t-butylperoxy) cyclohexyl) propane, tri (t-butylperoxy) triazine, tri (t-butylperoxy) Trimellitate, polyether poly-t-butylperoxy carbonate, t-butylperoxy methylfumarate or t-butylperoxy ethylfumarate. The method of claim 4, wherein A method for producing a heat resistant resin, wherein the mixing ratio of the bifunctional group-containing initiator: 4 or more functional group-containing initiators is 4: 1 to 3: 2 by weight. The method of claim 1, The reaction solvent is a method for producing a heat-resistant resin, characterized in that at least one selected from the group consisting of ethylbenzene, toluene, xylene and methyl ethyl ketone. The method of claim 1, The polymerization of the heat-resistant resin of the step (a) is polymerized such that the monomer mixture, the initiator mixture and the reaction solvent are kept for 4 to 6 hours at a temperature condition of 100 to 130 ° C. in the first reactor so that the polymerization conversion rate is 40 to 55 wt%. And, in the second reaction tank to maintain for 2 to 4 hours at a temperature of 100 to 130 ℃ temperature polymerization method for producing a heat-resistant resin, characterized in that the polymerization conversion to 50 to 70% by weight. The method of claim 1, Condensing the unreacted monomer and the solvent volatilized in the step (b) and re-introduced in the polymerization reaction of the step (a) further comprising the step of producing a heat-resistant resin. The heat resistant resin manufactured by the method of any one of Claims 1-10. The method of claim 11, The glass transition temperature (Tg) of the said heat resistant resin is 124 degreeC or more, The heat resistant resin characterized by the above-mentioned.