CN117043204A

CN117043204A - Process for preparing polymers

Info

Publication number: CN117043204A
Application number: CN202380010629.1A
Authority: CN
Inventors: 洪晟元; 李亨燮; 李大雨; 金吴利; 朱玟彻; 申珉承; 金仁秀
Original assignee: LG Chem Ltd
Current assignee: LG Chem Ltd
Priority date: 2022-01-17
Filing date: 2023-01-17
Publication date: 2023-11-10

Abstract

The present application relates to a method for preparing a polymer, comprising: adding an alkyl-substituted aromatic vinyl monomer and a vinyl cyanide monomer into a reactor and initiating polymerization; and conducting polymerization while continuously adding the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator to the reactor, wherein the continuous addition of the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator is started when the polymerization conversion is 10% to 30%, and the continuous addition of the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator is stopped when the polymerization conversion is 70% to 80%.

Description

Process for preparing polymers

Technical Field

Cross-reference to related applications

The present application claims priority and benefit from korean patent application No.10-2022-0006608, filed on 1 month 17 of 2022, and korean patent application No.10-2023-0006115, filed on 1 month 16 of 2023, the disclosures of which are incorporated herein by reference in their entireties.

The present application relates to a method for preparing a polymer, and more particularly, to a method for preparing a polymer having improved mechanical properties and processability by widening a molecular weight distribution while maintaining a proper level of weight average molecular weight.

Background

The polymer comprising vinyl cyanide-based monomer units and aromatic vinyl-based monomer units may be prepared by one or more methods selected from the group consisting of bulk polymerization, suspension polymerization, and emulsion polymerization. Among these methods, bulk polymerization has advantages such as high yield (because continuous polymerization can be performed) and high purity (because no additives are added). However, bulk polymerization has disadvantages such as low polymerization degree (because of high viscosity of a polymerization solution in the reaction) and difficulty in controlling the reaction heat. In order to solve the disadvantages of bulk polymerization, a method of preparing a polymer by suspension polymerization has been proposed.

Meanwhile, in order to increase heat resistance, a method of preparing a heat resistant polymer by introducing an aromatic vinyl monomer unit, particularly an alkyl-substituted aromatic vinyl monomer unit, as a component into the polymer has been proposed. However, heat resistant polymers do not exhibit excellent processability due to the high glass transition temperature. Processability of the heat-resistant polymer is related to melt flow index, and in order to increase melt flow index, the heat-resistant polymer needs to be used in a state of being mixed with a lubricant, or the weight average molecular weight of the heat-resistant polymer needs to be reduced. However, the use of a large amount of lubricant and low weight average molecular weight results in deterioration of heat resistance and chemical resistance of the heat resistant polymer.

[ related art literature ]

[ patent literature ]

(patent document 1) KR1646311B

Disclosure of Invention

Technical problem

The present invention aims to provide a method for producing a polymer whose mechanical properties and processability are improved by widening a molecular weight distribution while maintaining a proper level of weight average molecular weight.

Technical proposal

(1) In one aspect, the invention provides a method of preparing a polymer, the method comprising: adding an alkyl-substituted aromatic vinyl monomer and a vinyl cyanide monomer into a reactor and initiating polymerization; and conducting polymerization while continuously adding the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator to the reactor, wherein the continuous addition of the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator is started when the polymerization conversion is 10% to 30%, and the continuous addition of the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator is stopped when the polymerization conversion is 70% to 80%.

(2) According to (1), the present invention provides a method for producing a polymer, wherein the continuous addition of the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator is started when the polymerization conversion is 15% to 25%.

(3) According to (1) or (2), the present invention provides a method for producing a polymer, wherein the continuous addition of the alkyl-substituted aromatic vinyl-based monomer and the polyfunctional initiator is terminated when the polymerization conversion is 70% to 75%.

(4) The present invention provides a method for producing a polymer according to any one of (1) to (3), wherein the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator are continuously added in a mixed state.

(5) The present invention provides a method for producing a polymer according to any one of (1) to (4), wherein the amount of the alkyl-substituted aromatic vinyl-based monomer continuously added is 10 parts by weight to 30 parts by weight relative to 100 parts by weight of the total amount of the monomers added in the method for producing a polymer.

(6) The present invention provides a method for producing a polymer according to any one of (1) to (5), wherein the amount of the continuously added polyfunctional initiator is 0.1 to 0.5 parts by weight relative to 100 parts by weight of the total amount of the monomers added in the method for producing a polymer.

(7) The present invention provides a process for producing a polymer according to any one of (1) to (6), wherein a polyfunctional initiator is added in initiation of polymerization.

(8) The present invention provides a method for producing a polymer according to any one of (1) to (7), wherein the total amount of the polyfunctional initiator added in the method for producing a polymer is 0.4 parts by weight to 0.8 parts by weight with respect to 100 parts by weight of the total amount of the monomers added in the method for producing a polymer.

(9) The present invention provides a method for producing a polymer according to any one of (1) to (8), wherein the polyfunctional initiator is one or more selected from the group consisting of 2, 2-bis (4, 4-di (t-butylperoxy) cyclohexyl) propane, 1-bis (t-butylperoxy) cyclohexane, 1-bis (t-pentylperoxy) cyclohexane, 1-bis (t-butylperoxy) -3, 5-trimethylcyclohexane and polyether poly (t-butylperoxycarbonate).

(10) The present invention provides a method for producing a polymer according to any one of (1) to (9), wherein the polymerization is suspension polymerization.

Advantageous effects

Since the polymer according to the preparation method of the present invention achieves a broad molecular weight distribution while maintaining a proper level of weight average molecular weight, mechanical properties can be excellent and processability can be significantly improved.

Detailed Description

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to common meanings or meanings in dictionary, and should be construed as having meanings and concepts consistent with the technical concept of the present invention based on the principle that the inventor can properly define concepts of the terms in order to describe their invention in the best way.

As used herein, the term "polymerization conversion" refers to the degree of polymer formation by polymerization of monomers and can be calculated by the following equation.

Polymerization conversion (%) = [ (total weight of monomer added until polymerization termination) - (total weight of unreacted monomer when polymerization conversion is measured) ]/(total weight of monomer added until polymerization termination) ×100

As used herein, the term "vinyl cyanide monomer" may be one or more selected from acrylonitrile, methacrylonitrile, 2-ethyl-acrylonitrile, and 2-chloroacrylonitrile. As the vinyl cyanide monomer, acrylonitrile is preferable. The units derived from vinyl cyanide monomer may be vinyl cyanide monomer units.

As used herein, the term "alkyl-substituted aromatic vinyl monomer" may be one or more selected from the group consisting of alpha-methylstyrene, para-methylstyrene and 2, 4-dimethylstyrene. As the aromatic vinyl monomer, α -methylstyrene is preferable. The unit derived from the alkyl-substituted aromatic vinyl monomer may be an alkyl-substituted aromatic vinyl monomer unit.

As used herein, the term "aqueous solvent" may be ion exchanged water or deionized water.

As used herein, the term "suspending agent" may be one or more selected from the group consisting of water-soluble polyvinyl alcohol, partially hydrolyzed polyvinyl alcohol, polyacrylic acid, polymers of vinyl acetate and maleic anhydride, hydroxypropyl methylcellulose, gelatin, calcium phosphate, tricalcium phosphate, hydroxyapatite, sorbitan monolaurate, sorbitan trioleate, polyoxyethylene, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, and dioctyl sodium sulfosuccinate. As the suspending agent, tricalcium phosphate is preferable.

1. Process for preparing polymers

A method of preparing a polymer according to an embodiment of the present invention includes: adding an alkyl-substituted aromatic vinyl monomer and a vinyl cyanide monomer into a reactor and initiating polymerization; and conducting polymerization while continuously adding the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator to the reactor, wherein the continuous addition of the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator is started when the polymerization conversion is 10% to 30%, and the continuous addition of the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator is stopped when the polymerization conversion is 70% to 80%.

Hereinafter, a method of preparing a polymer according to an embodiment of the present invention will be described in detail.

1) Initiation of polymerization

First, an alkyl-substituted aromatic vinyl monomer and a vinyl cyanide monomer are added to a reactor, and polymerization is initiated.

When the alkyl-substituted aromatic vinyl monomer and the vinyl cyanide monomer are added before the polymerization is initiated, the alkyl-substituted aromatic vinyl monomer is polymerized together in the course of the polymerization, and thus, the polymerization conversion of the alkyl-substituted aromatic vinyl monomer can be improved at an early stage of the polymerization.

The total amount of the monomers added before the initiation of polymerization may be 70 to 90 parts by weight, preferably 75 to 85 parts by weight, relative to 100 parts by weight of the total amount of the monomers added in the method of preparing a polymer. When the above conditions are satisfied, a polymer having a uniform composition, excellent color characteristics, and improved mechanical properties due to a high weight average molecular weight can be prepared.

The amount of the alkyl-substituted aromatic vinyl-based monomer added before the polymerization initiation may be 50 to 75 parts by weight, preferably 55 to 70 parts by weight, relative to 100 parts by weight of the total amount of monomers added before the polymerization initiation. Further, the amount of the vinyl cyanide monomer added before the polymerization initiation may be 25 to 50 parts by weight, preferably 30 to 45 parts by weight, relative to the total amount of the monomers added before the polymerization initiation. When the above conditions are satisfied, a polymer having a uniform composition, excellent color characteristics, and improved mechanical properties due to a high weight average molecular weight can be prepared. In addition, the final polymerization conversion increases, whereby the production efficiency can be improved.

The polymerization is preferably suspension polymerization, which is easily controlled by using an aqueous solvent as a medium, has a high yield, and includes a simple washing process.

The suspension polymerization may be initiated in the presence of an initiator, a suspending agent and a suspending aid. In addition, the initiator, suspending agent and suspending aid may be added prior to initiation of the polymerization.

The initiator may be selected from the group consisting of 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, di (t-butylperoxy-isopropyl) benzene, t-butylcumene peroxide, di (t-amyl) -peroxide, dicumyl peroxide, butyl 4, 4-di (t-butylperoxy) valerate, t-butylperoxy benzoate, 2-di (t-butylperoxy) butane, t-amyl peroxy benzoate, t-butylperoxy acetate, t-butylperoxy- (2-ethylhexyl) carbonate, t-butylperoxy isopropyl carbonate tert-butylperoxy-3, 5-trimethylhexanoate, tert-amyl peroxyacetate, tert-amyl peroxy- (2-ethylhexyl) carbonate, 1-di (tert-butylperoxy) -3, 5-trimethylcyclohexane, 1-di (tert-amyl peroxy) cyclohexane t-butyl-monoperoxymaleate, 1' -azobis (hexahydrobenzonitrile), 2-bis (4, 4-di (t-butylperoxy) cyclohexyl) propane, 1-bis (t-butylperoxy) cyclohexane, and polyether poly (t-butylperoxycarbonate). Among those listed above, one or more selected from the group consisting of 2, 2-bis (4, 4-bis (t-butylperoxy) cyclohexyl) propane, 1-bis (t-butylperoxy) cyclohexane, 1-bis (t-amylperoxy) cyclohexane, 1-bis (t-butylperoxy) -3, 5-trimethylcyclohexane, and polyether poly (t-butylperoxycarbonate), which are polyfunctional initiators capable of improving the polymerization rate at relatively low temperatures, are preferably used.

The amount of the initiator may be 0.1 to 0.5 parts by weight, preferably 0.2 to 0.4 parts by weight, relative to 100 parts by weight of the total amount of the monomers added in the method of preparing a polymer. When the above condition is satisfied, the final polymerization conversion of the polymer can be increased, and the polymerization rate can be easily controlled. Further, deterioration of the color characteristics and weight average molecular weight of the polymer can be prevented.

The suspending agent may be present in an amount of 0.7 to 2.0 parts by weight, preferably 1.o to 1.5 parts by weight, relative to 100 parts by weight of the total amount of monomers added in the method of preparing a polymer. When the above condition is satisfied, the average particle diameter of the polymer can be controlled to a desired diameter, and dispersion stability can be improved.

The weight ratio of suspending agent to suspending aid may be 200:1 to 300:1, preferably 220:1 to 280:1. when the above condition is satisfied, the average particle diameter of the polymer can be controlled to a desired diameter, and dispersion stability can be improved.

2) Polymerization proceeds

Next, polymerization is performed while continuously adding an alkyl-substituted aromatic vinyl monomer and a polyfunctional initiator to the reactor.

When polymerization is performed while continuously adding an alkyl-substituted aromatic vinyl monomer and a multifunctional initiator, it is possible to prepare a polymer having a high final polymerization conversion and significantly improved processability due to having an appropriate weight average molecular weight and a broad molecular weight distribution.

When the alkyl-substituted aromatic vinyl-based monomer is continuously added without continuously adding the polyfunctional initiator, the weight average molecular weight of the polymer is lowered, and thus, mechanical properties, particularly impact resistance, are deteriorated. Further, when an initiator other than a polyfunctional initiator is added, the color characteristics of the polymer deteriorate and the molecular weight distribution becomes narrow, and thus, a polymer having improved processability may not be produced.

Further, since the polyfunctional initiator is added in a small amount in the polymerization as compared with the monomer, it may not be easy to continuously add the polyfunctional initiator alone. Therefore, for process convenience, it is preferable to continuously add the alkyl-substituted aromatic vinyl-based monomer and the multifunctional initiator in a mixed state.

Further, even if the polyfunctional initiator is continuously added, when the alkyl-substituted aromatic vinyl monomer is added in portions before the polymerization initiation and the alkyl-substituted aromatic vinyl monomer is not continuously added after the polymerization initiation, an excessive amount of the alkyl-substituted aromatic vinyl monomer having a low polymerization rate exists at an early stage of the polymerization, and thus, the polymerization rate is significantly lowered and the polymerization conversion of the alkyl-substituted aromatic vinyl monomer at the early stage of the polymerization is significantly lowered. Thus, a polymer having a non-uniform composition throughout the polymerization and having deteriorated color characteristics may be prepared. In addition, the alkyl-substituted aromatic vinyl monomer reacts with the vinyl cyanide monomer or the like too late in the latter stage of polymerization, and thus, an excessive amount of oligomer is generated.

However, when the alkyl-substituted aromatic vinyl monomer is continuously added, the alkyl-substituted aromatic vinyl monomer can be polymerized at an early stage of polymerization, and thus, deterioration in polymer color caused by reaction of an excessive amount of vinyl cyanide monomer at an early stage of polymerization can be prevented.

In addition, the vinyl cyanide-based monomer is not continuously added before the initiation of the polymerization but is preferably added in portions to prevent the polymerization of a large amount of the vinyl cyanide-based monomer in the latter stage of the polymerization.

Meanwhile, when the polymerization conversion is 10% to 30%, preferably when the polymerization conversion is 15% to 25%, the continuous addition of the alkyl-substituted aromatic vinyl-based monomer and the polyfunctional initiator may be started. When the above conditions are satisfied, a polymer having a uniform composition, improved color characteristics, and improved mechanical properties can be prepared. However, when the continuous addition is started earlier than the above-described time point, the weight average molecular weight of the polymer decreases, and therefore, the mechanical properties may deteriorate. Further, when the continuous addition is started at a time later than the above-described time point, the continuously added monomers are not mixed in the reaction system, and therefore, the transparency of the polymer is lowered, and the polymerization conversion is lowered. Therefore, the production efficiency may be lowered.

When the polymerization conversion is 70% to 80%, preferably when the polymerization conversion is 70% to 75%, the continuous addition of the alkyl-substituted aromatic vinyl-based monomer and the polyfunctional initiator may be terminated. When the above conditions are satisfied, a polymer having a high final polymerization conversion and significantly improved processability due to having an appropriate weight average molecular weight and a broad molecular weight distribution can be produced. However, when the continuous addition is terminated earlier than the above-described time point, the effect resulting from the continuous addition of the monomer deteriorates. Further, when the continuous addition is terminated at a time later than the above-described time point, the monomer does not penetrate into the polymer, and thus, the polymer having a nonuniform composition is produced. Therefore, the transparency of the polymer is lowered.

Since the amount of the polyfunctional initiator to be added is small, in the case where the alkyl-substituted aromatic vinyl-based monomer is not continuously added, it is impossible to start continuous addition of the polyfunctional initiator when the polymerization conversion is 10% to 30% and to terminate continuous addition of the polyfunctional initiator when the polymerization conversion is 70% to 80%. In particular, it is difficult to satisfy the continuous addition condition of the current polymerization apparatus due to the small amount of the multifunctional initiator added. Therefore, it is impossible to continuously add the polyfunctional initiator alone at the above-described time points.

In the case where the polyfunctional initiator is not continuously added, the continuous addition of the alkyl-substituted aromatic vinyl-based monomer is started when the polymerization conversion is 10% to 30% and terminated when the polymerization conversion is 70% to 80%, and thus the polymerization rate is excessively increased, and the weight average molecular weight of the resulting polymer is excessively reduced. Therefore, the mechanical properties of the polymer such as impact resistance and the like are deteriorated.

The amount of the continuously added alkyl-substituted aromatic vinyl-based monomer may be 10 to 30 parts by weight, preferably 15 to 25 parts by weight, relative to 100 parts by weight of the total amount of the monomers added in the method of preparing a polymer. When the above conditions are satisfied, a polymer having improved color characteristics and weight average molecular weight can be produced, and also the production efficiency can be improved due to a high final polymerization conversion.

The amount of the continuously added multifunctional initiator may be 0.1 to 0.5 parts by weight, preferably 0.2 to 0.4 parts by weight, relative to 100 parts by weight of the total amount of the monomers added in the method of preparing a polymer. When the above conditions are satisfied, a polymer having improved weight average molecular weight and color characteristics can be produced.

The total amount of the multifunctional initiator added in the method of preparing a polymer may be 0.4 to 0.8 parts by weight, preferably 0.5 to 0.7 parts by weight, relative to 100 parts by weight of the total amount of the monomers added in the method of preparing a polymer. When the above conditions are satisfied, a polymer having improved color characteristics and weight average molecular weight can be produced, and also the production efficiency can be improved due to a high final polymerization conversion.

The multifunctional initiator may be one or more selected from the group consisting of 2, 2-bis (4, 4-bis (t-butylperoxy) cyclohexyl) propane, 1-bis (t-butylperoxy) cyclohexane, 1-bis (t-amylperoxy) cyclohexane, 1-bis (t-butylperoxy) -3, 5-trimethylcyclohexane and polyether poly (t-butylperoxycarbonate).

3) Termination of polymerization

After step 2), when the polymerization conversion is 95% or more, the polymerization may be terminated.

When the polymerization is terminated at the above-described time point, the polymerization and aging process may be further performed after the continuous addition of the alkyl-substituted aromatic vinyl-based monomer is terminated. Accordingly, the alkyl-substituted aromatic vinyl-based monomer which is continuously added relatively late can sufficiently participate in the polymerization to suppress the generation of oligomers, and a polymer having a uniform composition throughout the polymerization can be produced.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. It should be understood, however, that the invention may be embodied in various forms and that the embodiments are not intended to limit the invention.

Example 1

< preparation of first reaction solution >

50 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.2 part by weight of initiator (2, 2-bis (4, 4-di (t-butylperoxy) cyclohexyl) propane), 1.3 parts by weight of suspending agent (tricalcium phosphate) and 0.005 parts by weight of suspending aid (commercially available from TOHO Chemical Industry co., ltd. RS-710) were uniformly mixed to prepare a first reaction solution.

< preparation of second reaction solution >

20 parts by weight of alpha-methylstyrene (AMS) and 0.4 parts by weight of initiator (2, 2-bis (4, 4-di (t-butylperoxy) cyclohexyl) propane) were uniformly mixed to prepare a second reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution at a constant rate from the point in time when the polymerization conversion reached 10% to the point in time when the polymerization conversion reached 75%. In this case, the time taken for the polymerization conversion to reach 10% after the initiation of polymerization was 60 minutes, and the continuous addition time of the second reaction solution was 420 minutes.

After the continuous addition of the second reaction solution was terminated, polymerization was performed while raising the temperature in the reactor to 105 ℃ at a constant rate over 20 minutes, polymerization was performed while maintaining the temperature in the reactor at 105 ℃ for 220 minutes, and polymerization was terminated to obtain a polymerization syrup.

Formic acid was added to the reactor so that the polymerization syrup had a pH of 2.5, and the resulting polymerization syrup was washed, dehydrated and dried to prepare a bead polymer.

Example 2

The entire amount of the first reaction solution of example 1 was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution of example 1 at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 75%. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 120 minutes, and the continuous addition time of the second reaction solution was 360 minutes.

After the continuous addition of the second reaction solution of example 1 was terminated, polymerization was performed while raising the temperature in the reactor to 105 ℃ at a constant rate over 20 minutes, polymerization was performed while maintaining the temperature in the reactor at 105 ℃ for 220 minutes, and polymerization was terminated to obtain a polymerization syrup.

Example 3

The entire amount of the first reaction solution of example 1 was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution of example 1 at a constant rate from the point in time when the polymerization conversion reached 30% to the point in time when the polymerization conversion reached 75%. In this case, the time taken for the polymerization conversion to reach 30% after the initiation of polymerization was 180 minutes, and the continuous addition time of the second reaction solution was 300 minutes.

Example 4

The entire amount of the first reaction solution of example 1 was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution of example 1 at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 70%. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 120 minutes, and the continuous addition time of the second reaction solution was 300 minutes.

After the continuous addition of the second reaction solution of example 1 was terminated, polymerization was performed while maintaining the temperature in the reactor at 100℃for 60 minutes, then raising the temperature in the reactor to 105℃at a constant rate over 20 minutes, polymerization was performed for 220 minutes while maintaining the temperature in the reactor at 105℃and the polymerization was terminated to obtain a polymerization syrup.

Example 5

The entire amount of the first reaction solution of example 1 was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution of example 1 at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 80%. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 120 minutes, and the continuous addition time of the second reaction solution was 390 minutes.

After the continuous addition of the second reaction solution of example 1 was terminated, polymerization was performed while raising the temperature in the reactor to 105 ℃ at a constant rate over 20 minutes, polymerization was performed for 190 minutes while maintaining the temperature in the reactor at 105 ℃, and polymerization was terminated to obtain a polymerization syrup.

Example 6

< preparation of first reaction solution >

50 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.4 part by weight of initiator (2, 2-bis (4, 4-di (t-butylperoxy) cyclohexyl) propane), 1.3 parts by weight of suspending agent (tricalcium phosphate) and 0.005 parts by weight of suspending aid (commercially available from TOHO Chemical Industry co., ltd. RS-710) were uniformly mixed to prepare a first reaction solution.

< preparation of second reaction solution >

20 parts by weight of alpha-methylstyrene (AMS) and 0.2 parts by weight of initiator (2, 2-bis (4, 4-di (t-butylperoxy) cyclohexyl) propane) were uniformly mixed to prepare a second reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 75%. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 90 minutes, and the continuous addition time of the second reaction solution was 390 minutes.

Example 7

< preparation of first reaction solution >

< preparation of second reaction solution >

20 parts by weight of alpha-methylstyrene (AMS) and 0.2 parts by weight of an initiator (polyether poly (t-butylperoxycarbonate)) were uniformly mixed to prepare a second reaction solution.

< preparation of Polymer >

After the continuous addition of the second reaction solution was terminated, polymerization was performed while raising the temperature in the reactor to 110 ℃ at a constant rate over 20 minutes, polymerization was performed while maintaining the temperature in the reactor at 110 ℃ for 220 minutes, and polymerization was terminated to obtain a polymerization syrup.

Example 8

< preparation of first reaction solution >

50 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.2 part by weight of AN initiator (1, 1-di (t-butylperoxy) cyclohexane), 1.3 parts by weight of a suspending agent (tricalcium phosphate) and 0.005 parts by weight of a suspending aid (commercially available RS-710 from TOHO Chemical Industry co., ltd.) were uniformly mixed to prepare a first reaction solution.

< preparation of second reaction solution >

20 parts by weight of alpha-methylstyrene (AMS) and 0.4 parts by weight of an initiator (1, 1-di (t-butylperoxy) cyclohexane) were uniformly mixed to prepare a second reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, and the temperature inside the reactor was raised to 95 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 75%. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 120 minutes, and the continuous addition time of the second reaction solution was 360 minutes.

After the continuous addition of the second reaction solution was terminated, polymerization was performed while raising the temperature in the reactor to 100 ℃ at a constant rate over 20 minutes, polymerization was performed while maintaining the temperature in the reactor at 100 ℃ for 220 minutes, and polymerization was terminated to obtain a polymerization syrup.

Example 9

< preparation of first reaction solution >

50 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.4 part by weight of AN initiator (1, 1-di (t-butylperoxy) cyclohexane), 1.3 parts by weight of a suspending agent (tricalcium phosphate) and 0.005 parts by weight of a suspending aid (commercially available RS-710 from TOHO Chemical Industry co., ltd.) were uniformly mixed to prepare a first reaction solution.

< preparation of second reaction solution >

20 parts by weight of alpha-methylstyrene (AMS) and 0.2 parts by weight of an initiator (1, 1-di (t-butylperoxy) cyclohexane) were uniformly mixed to prepare a second reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, and the temperature inside the reactor was raised to 95 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 75%. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 90 minutes, and the continuous addition time of the second reaction solution was 390 minutes.

Comparative example 1

The entire amount of the first reaction solution of example 1 was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution of example 1 at a constant rate from the point in time when the polymerization conversion reached 7% to the point in time when the polymerization conversion reached 75%. In this case, the time taken for the polymerization conversion to reach 7% after the initiation of polymerization was 30 minutes, and the continuous addition time of the second reaction solution was 450 minutes.

Comparative example 2

The entire amount of the first reaction solution of example 1 was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution of example 1 at a constant rate from the point in time when the polymerization conversion reached 34% to the point in time when the polymerization conversion reached 75%. In this case, the time taken for the polymerization conversion to reach 34% after the initiation of polymerization was 200 minutes, and the continuous addition time of the second reaction solution was 280 minutes.

Comparative example 3

The entire amount of the first reaction solution of example 1 was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution of example 1 at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 66%. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 120 minutes, and the continuous addition time of the second reaction solution was 270 minutes.

After the continuous addition of the second reaction solution of example 1 was terminated, polymerization was performed while maintaining the temperature in the reactor at 100℃for 90 minutes, then raising the temperature in the reactor to 105℃at a constant rate over 20 minutes, polymerization was performed for 220 minutes while maintaining the temperature in the reactor at 105℃and the polymerization was terminated to obtain a polymerization syrup.

Comparative example 4

The entire amount of the first reaction solution of example 1 was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of the polymerization, the polymerization was carried out while continuously adding the entire amount of the second reaction solution of example 1 at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 83%. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 120 minutes, and the continuous addition time of the second reaction solution was 420 minutes.

After the continuous addition of the second reaction solution of example 1 was terminated, polymerization was performed while raising the temperature in the reactor to 105 ℃ at a constant rate over 20 minutes, polymerization was performed for 160 minutes while maintaining the temperature in the reactor at 105 ℃, and polymerization was terminated to obtain a polymerization syrup.

Comparative example 5

< preparation of first reaction solution >

< preparation of second reaction solution >

20 parts by weight of alpha-methylstyrene (AMS) and 0.2 parts by weight of an initiator (t-butylperoxy benzoate) were uniformly mixed to prepare a second reaction solution.

< preparation of Polymer >

Comparative example 6

< preparation of first reaction solution >

< preparation of second reaction solution >

20 parts by weight of alpha-methylstyrene (AMS) and 0.2 parts by weight of an initiator (dicumyl peroxide) were uniformly mixed to prepare a second reaction solution.

< preparation of Polymer >

After the continuous addition of the second reaction solution was terminated, polymerization was performed while raising the temperature in the reactor to 130 ℃ at a constant rate over 40 minutes, polymerization was performed while maintaining the temperature in the reactor at 130 ℃ for 200 minutes, and polymerization was terminated to obtain a polymerization syrup.

Comparative example 7

< preparation of first reaction solution >

< preparation of second reaction solution >

< preparation of Polymer >

After the continuous addition of the second reaction solution was terminated, polymerization was performed while raising the temperature in the reactor to 120 ℃ at a constant rate over 30 minutes, polymerization was performed while maintaining the temperature in the reactor at 120 ℃ for 210 minutes, and polymerization was terminated to obtain a polymerization slurry.

Comparative example 8

< preparation of first reaction solution >

50 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.6 part by weight of initiator (2, 2-bis (4, 4-di (t-butylperoxy) cyclohexyl) propane), 1.3 parts by weight of suspending agent (tricalcium phosphate) and 0.005 parts by weight of suspending aid (commercially available from TOHO Chemical Industry co., ltd. RS-710) were uniformly mixed to prepare a first reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, and the temperature inside the reactor was raised to 100 ℃ to initiate polymerization. After the initiation of polymerization, polymerization was performed while continuously adding 20 parts by weight of α -methylstyrene (AMS) at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 75%. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 60 minutes, and the continuous addition time of α -methylstyrene was 420 minutes.

Polymerization was performed while raising the temperature in the reactor to 110 ℃ at a constant rate over 20 minutes, polymerization was performed while maintaining the temperature in the reactor at 110 ℃ for 220 minutes, and polymerization was terminated to obtain a polymerization syrup.

Comparative example 9

< preparation of first reaction solution >

50 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.6 part by weight of AN initiator (1, 1-di (t-butylperoxy) cyclohexane), 1.3 parts by weight of a suspending agent (tricalcium phosphate) and 0.005 parts by weight of a suspending aid (commercially available RS-710 from TOHO Chemical Industry co., ltd.) were uniformly mixed to prepare a first reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, and the temperature inside the reactor was raised to 95 ℃ to initiate polymerization. After the initiation of polymerization, polymerization was performed while continuously adding 20 parts by weight of α -methylstyrene (AMS) at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 75%. The polymerization was carried out while continuously adding the entire amount of the second reaction solution at a constant rate. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 120 minutes, and the continuous addition time of α -methylstyrene (AMS) was 360 minutes.

Polymerization was performed while raising the temperature in the reactor to 100 ℃ at a constant rate over 20 minutes, polymerization was performed while maintaining the temperature in the reactor at 100 ℃ for 220 minutes, and polymerization was terminated to obtain a polymerization syrup.

Comparative example 10

< preparation of first reaction solution >

50 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.6 parts by weight of AN initiator (benzoyl peroxide), 1.3 parts by weight of a suspending agent (tricalcium phosphate) and 0.005 parts by weight of a suspending aid (commercially available from TOHO Chemical Industry co., ltd. RS-710) were uniformly mixed to prepare a first reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, and the temperature inside the reactor was raised to 75 ℃ to initiate polymerization. After the initiation of polymerization, polymerization was performed while continuously adding 20 parts by weight of α -methylstyrene (AMS) at a constant rate from the point of time when the polymerization conversion reached 20% to the point of time when the polymerization conversion reached 60%. The polymerization was carried out while continuously adding the entire amount of the second reaction solution at a constant rate. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 120 minutes, and the continuous addition time of α -methylstyrene (AMS) was 360 minutes.

Polymerization was performed while raising the temperature in the reactor to 90 ℃ at a constant rate over 20 minutes, polymerization was performed while maintaining the temperature in the reactor at 90 ℃ for 220 minutes, and polymerization was terminated to obtain a polymerization syrup.

Comparative example 11

< preparation of first reaction solution >

50 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.6 parts by weight of AN initiator (polyether poly (t-butylperoxycarbonate)), 1.3 parts by weight of a suspending agent (tricalcium phosphate) and 0.005 parts by weight of a suspending aid (commercially available from TOHO Chemical Industry co., ltd. RS-710) were uniformly mixed to prepare a first reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, and the temperature inside the reactor was raised to 105 ℃ to initiate polymerization. After the initiation of polymerization, polymerization was performed while continuously adding 20 parts by weight of α -methylstyrene (AMS) at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 75%. The polymerization was carried out while continuously adding the entire amount of the second reaction solution at a constant rate. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 120 minutes, and the continuous addition time of α -methylstyrene (AMS) was 360 minutes.

Comparative example 12

< preparation of first reaction solution >

50 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.6 parts by weight of AN initiator (t-butylperoxy benzoate), 1.3 parts by weight of a suspending agent (tricalcium phosphate), and 0.005 parts by weight of a suspending aid (commercially available from TOHO Chemical Industry co., ltd. RS-710) were uniformly mixed to prepare a first reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, and the temperature inside the reactor was raised to 110 ℃ to initiate polymerization. After the initiation of polymerization, polymerization was performed while continuously adding 20 parts by weight of α -methylstyrene (AMS) at a constant rate from the point in time when the polymerization conversion reached 20% to the point in time when the polymerization conversion reached 75%. The polymerization was carried out while continuously adding the entire amount of the second reaction solution at a constant rate. In this case, the time taken for the polymerization conversion to reach 20% after the initiation of polymerization was 120 minutes, and the continuous addition time of α -methylstyrene (AMS) was 360 minutes.

Polymerization was performed while raising the temperature in the reactor to 120 ℃ at a constant rate over 20 minutes, polymerization was performed while maintaining the temperature in the reactor at 120 ℃ for 220 minutes, and polymerization was terminated to obtain a polymerization syrup.

Comparative example 13

< preparation of first reaction solution >

70 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.6 part by weight of initiator (2, 2-bis (4, 4-di (t-butylperoxy) cyclohexyl) propane), 1.3 parts by weight of suspending agent (tricalcium phosphate) and 0.005 parts by weight of suspending aid (commercially available RS-710 from TOHO Chemical Industry co., ltd.) were uniformly mixed to prepare a first reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, the temperature inside the reactor was raised to 100 ℃ to initiate polymerization, and polymerization was performed for 480 minutes. Subsequently, polymerization was performed while raising the temperature in the reactor to 105 ℃ at a constant rate over 20 minutes, polymerization was performed while maintaining the temperature in the reactor at 105 ℃ for 220 minutes, and polymerization was terminated to obtain a polymerization syrup.

Comparative example 14

< preparation of first reaction solution >

70 parts by weight of α -methylstyrene (AMS), 30 parts by weight of Acrylonitrile (AN), 150 parts by weight of ion-exchanged water, 0.6 part by weight of AN initiator (1, 1-di (t-butylperoxy) cyclohexane), 1.3 parts by weight of a suspending agent (tricalcium phosphate) and 0.005 parts by weight of a suspending aid (commercially available RS-710 from TOHO Chemical Industry co., ltd.) were uniformly mixed to prepare a first reaction solution.

< preparation of Polymer >

The entire amount of the first reaction solution was added to the reactor, the temperature in the reactor was raised to 95 ℃ to initiate polymerization, and polymerization was performed for 480 minutes. Subsequently, polymerization was performed while raising the temperature in the reactor to 100 ℃ at a constant rate over 20 minutes, polymerization was performed while maintaining the temperature in the reactor at 100 ℃ for 220 minutes, and polymerization was terminated to obtain a polymerization syrup.

Test example 1

Polymerization conversion of the polymerization pastes according to examples and comparative examples was measured by the following method, and the results thereof are shown in tables 1 to 5.

(1) Polymerization conversion (%): calculated by the following equation.

Polymerization conversion (%) = { (total weight of monomer added until polymerization termination) - (total weight of unreacted monomer when polymerization conversion is measured) }/(total weight of monomer added until polymerization termination) ×100)

Test example 2

The physical properties of the polymers according to examples and comparative examples were measured by the following methods, and the results thereof are shown in tables 1 to 5 below.

(1) Color comparison: the bead polymer was added to the vial for color comparison and the polymer was dried under vacuum at 220 ℃ for 2 hours, then its color was evaluated. CIE Whiteness Index (WI) and CIE b values were measured, and Yellowness Index (YI) was measured according to ASTM D1925.

o (good): a whiteness index of greater than 80, a yellowness index of less than 3, and a b value of less than 2

Delta (general): a whiteness index of more than 70 and less than 80, a yellowness index of 3 to 4, and a b value of 2 to 3

X (difference): a whiteness index of 60 to 70, a yellowness index of more than 4, and a b value of more than 3

(2) Weight average molecular weight (g/mol): after the polymer was dissolved in Tetrahydrofuran (THF), it was measured by gel permeation chromatography (model name: PL GPC220, manufacturer: agilent Technologies) at 40℃using polystyrene as a standard material.

(3) Molecular weight distribution: the weight average molecular weight and the number average molecular weight were measured by the method described in (2) and calculated by dividing the weight average molecular weight by the number average molecular weight.

(4) Melt flow index (g/10 min): measured according to ASTM D1238 at 220℃and 10 kg.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

TABLE 5

Referring to tables 1 to 5, it can be seen that examples 1 to 9, in which the continuous addition of the alkyl-substituted aromatic vinyl-based monomer and the polyfunctional initiator was started when the polymerization conversion was 10% to 30%, and terminated when the polymerization conversion was 70% to 80%, exhibited high final polymerization conversion, excellent color characteristics, excellent mechanical properties due to having a high weight average molecular weight, and excellent processability due to having a broad molecular weight distribution and a high melt flow index. However, it can be seen that comparative example 1, in which the continuous addition of the alkyl-substituted aromatic vinyl-based monomer and the polyfunctional initiator was started when the polymerization conversion was 7%, exhibited deteriorated mechanical properties due to having a low weight average molecular weight and deteriorated processability due to having a narrow molecular weight distribution and a low melt flow index, compared with examples.

Further, in the case of comparative example 1 in which the continuous addition of the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator was started when the polymerization conversion rate was 34%, it can be seen that since the continuous addition of the alkyl-substituted aromatic vinyl monomer was started later, the polymer prepared at the early stage of the polymerization contained an excessive amount of vinyl cyanide monomer units, and thus, exhibited deteriorated color characteristics and deteriorated processability due to a low melt flow index, as compared with examples.

Further, it can be seen that comparative example 3, in which the continuous addition of the alkyl-substituted aromatic vinyl-based monomer and the polyfunctional initiator was terminated when the polymerization conversion rate was 66%, exhibited deteriorated color characteristics and deteriorated processability due to having a low melt flow index, compared with the examples.

Further, it can be seen that comparative example 4, in which the continuous addition of the alkyl-substituted aromatic vinyl-based monomer and the polyfunctional initiator was terminated when the polymerization conversion was 83%, exhibited deteriorated color characteristics, deteriorated mechanical properties due to having a low weight average molecular weight, and deteriorated processability due to having a narrow molecular weight distribution and a low melt flow index, compared with the examples.

It can be seen that comparative examples 5 to 7, in which the polyfunctional initiator was not used in the continuous addition, exhibited deteriorated color characteristics, deteriorated mechanical properties due to having a low weight average molecular weight, and deteriorated processability due to having a narrow molecular weight distribution and a low melt flow index, compared with examples.

It can be seen that comparative examples 8 and 9, in which the initiator was added only before the polymerization initiation and the initiator was not continuously added after the polymerization initiation, exhibited mechanical properties deteriorated due to having a low weight average molecular weight, compared with examples.

It can be seen that comparative example 10, in which benzoyl peroxide was used instead of the polyfunctional initiator before the polymerization initiation and the initiator was not continuously added after the polymerization initiation, exhibited significantly reduced final polymerization conversion and deteriorated mechanical properties due to very low weight average molecular weight, compared with the examples.

It can be seen that comparative example 11, in which a multifunctional initiator was used before the polymerization initiation and an initiator was not continuously added after the polymerization initiation, exhibited significantly deteriorated color characteristics and significantly deteriorated mechanical properties due to having a very low weight average molecular weight, compared with examples.

It can be seen that comparative example 12, in which t-butylperoxy benzoate was used instead of the polyfunctional initiator before the polymerization initiation and the initiator was not continuously added after the polymerization initiation, exhibited significantly deteriorated color characteristics and significantly deteriorated mechanical properties due to having a very low weight average molecular weight, compared with the examples.

It can be seen that comparative examples 13 and 14, in which the α -methylstyrene and the polyfunctional initiator were not continuously added after the initiation of polymerization, exhibited significantly deteriorated color characteristics and deteriorated mechanical properties due to having a low weight average molecular weight, compared with examples.

Claims

1. A method of preparing a polymer comprising:

adding an alkyl-substituted aromatic vinyl monomer and a vinyl cyanide monomer into a reactor and initiating polymerization; and

the polymerization is carried out while continuously adding the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator to the reactor,

wherein the continuous addition of the alkyl-substituted aromatic vinyl monomer and the polyfunctional initiator is started when the polymerization conversion is 10 to 30%,

the continuous addition of the alkyl-substituted aromatic vinyl-based monomer and the multifunctional initiator is terminated when the polymerization conversion is 70% to 80%.

2. The method of claim 1, wherein the continuous addition of the alkyl-substituted aromatic vinyl monomer and the multifunctional initiator is initiated when the polymerization conversion is 15% to 25%.

3. The method of claim 1, wherein the continuous addition of the alkyl-substituted aromatic vinyl monomer and the multifunctional initiator is terminated when the polymerization conversion is 70% to 75%.

4. The method according to claim 1, wherein the alkyl-substituted aromatic vinyl-based monomer and the polyfunctional initiator are continuously added in a mixed state.

5. The method according to claim 1, wherein the amount of the continuously added alkyl-substituted aromatic vinyl-based monomer is 10 to 30 parts by weight with respect to 100 parts by weight of the total amount of the monomers added in the method for preparing a polymer.

6. The method according to claim 1, wherein the amount of the continuously added multifunctional initiator is 0.1 to 0.5 parts by weight with respect to 100 parts by weight of the total amount of the monomers added in the method for preparing a polymer.

7. The method of claim 1, wherein a multifunctional initiator is added in the initiation of the polymerization.

8. The method according to claim 1, wherein the total amount of the multifunctional initiator added in the method of preparing a polymer is 0.4 to 0.8 parts by weight with respect to 100 parts by weight of the total amount of the monomers added in the method of preparing a polymer.

9. The method of claim 1, wherein the multifunctional initiator is one or more selected from the group consisting of 2, 2-bis (4, 4-di (t-butylperoxy) cyclohexyl) propane, 1-di (t-butylperoxy) cyclohexane, 1-di (t-amylperoxy) cyclohexane, 1-di (t-butylperoxy) -3, 5-trimethylcyclohexane, and polyether poly (t-butylperoxycarbonate).

10. The method of claim 1, wherein the polymerization is suspension polymerization.