KR20190063274A - Method for preparing copolymer - Google Patents

Abstract

The present invention relates to a method for manufacturing a copolymer comprising following steps of: introducing an aromatic vinyl-based monomer and a vinyl cyanide monomer into a reactor before initiating polymerization; heating the reactor; and after the completion of heating, continuously introducing the aromatic vinyl-based monomer to the heated reactor with a constant rate at the time when a polymerization conversion rate is 10% or less and polymerizing the same. According to the method for manufacturing the copolymer of the present invention, it is possible to manufacture the copolymer having a uniform composition throughout polymerization.

Description

[0001] METHOD FOR PREPARING COPOLYMER [0002]

The present invention relates to a process for producing a copolymer, and more particularly, to a process for producing a copolymer capable of producing a copolymer having a uniform composition throughout the polymerization.

The styrene-acrylonitrile (SAN) copolymer can be prepared by emulsion polymerization, suspension polymerization and bulk polymerization. Suspension polymerization is advantageous in that the amount of additives used is small and post-treatment is simple. Due to this advantage, it is possible to respond quickly if a small quantity of various items is required.

However, since acrylonitrile exhibits a slight water solubility, it is dissolved in a small amount of water at the initial stage of polymerization. As a result, the amount of acrylonitrile involved in the polymerization is small at the initial stage of polymerization, and as the polymerization proceeds, acrylonitrile participating in the polymerization increases, resulting in a difference in monomer composition in the polymerization system. As a result, the content of the components in the copolymer varies depending on the polymerization time, so that the composition of the polymer becomes uneven and the physical properties are not maintained uniformly.

KR10-0191420B

An object of the present invention is to provide a process for producing a copolymer capable of producing a copolymer having a uniform composition throughout the polymerization.

In order to solve the above-described problems, the present invention provides a method for producing a vinyl aromatic compound, which comprises: introducing an aromatic vinyl monomer and a vinyl cyan monomer into a reactor prior to initiation of polymerization; Heating the reactor; And a step of continuously polymerizing the aromatic vinyl monomer at a constant rate at the time when the polymerization conversion rate is 10% or less in the reactor which has been raised after the completion of elevated temperature, thereby polymerizing the copolymer.

Further, the present invention relates to a copolymer produced by the above-mentioned production method, which comprises an aromatic vinyl-based monomer-derived unit and a vinylcyanide-based monomer-derived unit, wherein the vinylcyanide monomer-derived unit Is not more than 0.7.

According to the process for producing a copolymer of the present invention, a copolymer having a uniform composition throughout the polymerization can be produced.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

In the present invention, the polymerization conversion ratio refers to the polymerization conversion rate of the monomer mixture, that is, the degree of polymerization of the monomers contained in the monomer mixture to form a polymer.

(%) = (Total content of the initially charged monomer mixture-total content of the unreacted monomer mixture) / (total content of the initially charged monomer mixture) 占 100

A method for producing a copolymer according to an embodiment of the present invention comprises: 1. introducing an aromatic vinyl monomer and a vinyl cyan monomer into a reactor before initiating polymerization; 2. heating the reactor; And 3. After completion of the temperature elevation, the step of polymerizing the aromatic vinyl-based monomer at a constant rate at a time when the polymerization conversion rate is 10% or less in the reactor which has been raised in temperature.

Hereinafter, each step of the method for producing a copolymer according to one embodiment of the present invention will be described in detail.

1. The first step

Before the initiation of the polymerization, the aromatic vinyl monomer and the vinyl cyan monomer are charged into the reactor.

Examples of the aromatic vinyl-based monomer may include at least one selected from the group consisting of styrene,? -Methylstyrene, p-bromostyrene, p-methylstyrene, p-chlorostyrene and o-bromostyrene, .

The vinyl cyan monomer is selected from the group consisting of acrylonitrile, methacrylonitrile, ethacrylonitrile, phenyl acrylonitrile,? -Chloronitrile,? -Chloroacrylonitrile and? -Cyanoethyl acrylonitrile Acrylonitrile, and acrylonitrile is preferable.

The weight ratio of the aromatic vinyl monomer to the vinyl cyan monomer may be 85:15 to 60:40, 80:20 to 65:35 or 70:30 to 75:25 in the process for producing the copolymer, 70:30 to 75:25 is preferable. When the above-mentioned range is satisfied, heat resistance, chemical resistance, mechanical properties and workability can be further improved.

The reactor may further contain at least one selected from the group consisting of initiators, suspending agents, molecular weight regulators and water.

The initiator may be a radical initiator and may be an azo-based radical initiator or a peroxy-clock radical initiator having a half-life temperature on a 10 hour basis of 65 to 110 ° C and an azo-type radical initiator having a half- Do.

The initiator may be at least one selected from the group consisting of 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2-methylbutyronitrile) Azo compounds such as 2,2'-azobis (2-methyl-N- (2-hydroxyethyl) propionamide), 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, Butyl peroxy-2-ethylhexanoate, t-butyl peroxydiethyl acetate, and t-butylperoxy (methylbenzoyl) peroxide, t-amylperoxy-2-ethylhexanoate, dibenzoyl peroxide, -Isobutyrate, and 1,1'-azobis (cyclohexanecarbonitrile) is preferred among them.

The initiator may be included in an amount of 0.09 to 0.40 parts by weight, 0.13 to 0.32 parts by weight, or 0.18 to 0.24 parts by weight, and 0.18 to 0.24 parts by weight, based on 100 parts by weight of the sum of the aromatic vinyl monomer and the vinyl cyan monomer. . When the above-mentioned range is satisfied, the polymerization conversion ratio of the copolymer can be further increased.

The suspending agent may be selected from the group consisting of water-soluble polyvinyl alcohol, partially saponified polyvinyl alcohol, polyacrylic acid, a copolymer of vinyl acetate and maleic anhydride, hydroxypropyl methylcellulose ), Gelatin, calcium phosphate, tricalcium phosphate hydroxyapatite, sorbitan monolaurate, sorbitan trioleate, polyoxyalkylene glycol, May be at least one member selected from the group consisting of polyoxyethylene, sodium lauryl sulfate, sodium dodecylbenzene sulfonic acid and sodium dioctylsulfosuccinate, Of these, tricalcium phosphate is preferred.

The suspending agent may be contained in an amount of 0.7 to 2.6 parts by weight, 1.0 to 2.0 parts by weight, or 1.3 to 1.5 parts by weight based on 100 parts by weight of the sum of the aromatic vinyl monomer and the vinyl cyan monomer, and 1.3 to 1.5 parts by weight thereof . When the above-mentioned range is satisfied, the particle diameter of the copolymer can be easily controlled, and dispersion stability can be improved.

The molecular weight regulator may be selected from the group consisting of mercaptans such as a-methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan and octyl mercaptan, halogenated hydrocarbons such as methylene chloride, methylene bromide, tetraethylthiuram disulfide , Dipentamethylenethiuram disulfide, diisopropylkantogen disulfide, and the like. Preferably t-dodecylmercaptan.

The molecular weight modifier may be contained in an amount of 0.03 to 0.10 parts by weight, 0.04 to 0.09 parts by weight, or 0.05 to 0.08 parts by weight, and 0.05 to 0.08 parts by weight, based on 100 parts by weight of the sum of the aromatic vinyl monomer and the vinyl cyan monomer. . When the above-mentioned range is satisfied, a copolymer having an appropriate weight average molecular weight, preferably a copolymer having a weight average molecular weight of 300,000 to 400,000 g / mol, can be produced.

Here, the content of the initiator, the suspending agent, and the molecular weight modifier is based on the total of 100 parts by weight of the aromatic vinyl monomer and the vinyl cyan monomer added in the process for producing a copolymer according to one embodiment of the present invention.

The water may be ion-exchanged water or deionized water.

2. Warm up  step

Then, the reactor is heated.

The reactor may be heated to 80 to 105 ° C, 85 to 100 ° C, or 90 to 95 ° C, and preferably 90 to 95 ° C.

When the temperature is raised to the above-mentioned temperature range, the polymerization conversion ratio of the copolymer can be increased, and the efficiency of the initiator can be increased.

On the other hand, in the step of raising the temperature of the reactor, the aromatic vinyl monomer and the vinyl cyan monomer introduced before the polymerization is started can be polymerized.

In addition, in the step of raising the temperature, the aromatic vinyl monomer and the vinyl cyan monomer may not be added.

3. Polymerization step

After the temperature rise is completed, the aromatic vinyl-based monomer is continuously charged at a constant rate at a time when the polymerization conversion rate is 10% or less in the reactor that has been heated.

After the temperature of the aromatic vinyl monomer is elevated, the content of the vinylcyanide monomer is increased, and the content of the vinylcyanide monomer increases as the polymerization time elapses. A copolymer having a uniform composition throughout the polymerization can be prepared.

If the aromatic vinyl monomer is continuously added at a polymerization conversion rate of more than 10%, the composition in the copolymer produced in the first half of the polymerization and the second half of the polymerization will be significantly changed, so that a copolymer having a uniform composition throughout the polymerization Can not.

Also, if the aromatic vinyl monomer is added all at once, a copolymer having an increased content of vinylcyanide monomer-derived units is produced as the polymerization proceeds, and thus a copolymer having a uniform composition can not be produced.

The aromatic vinyl monomer is preferably continuously charged at a constant rate at a polymerization conversion of 1 to 10%, and is most preferably continuously charged at a constant rate at a polymerization conversion of 1 to 5%. If the aromatic vinyl-based monomer is continuously introduced at the above point of time, a copolymer having a more uniform composition throughout the polymerization can be produced.

Here, the point of polymerization conversion may include the polymerization of the aromatic vinyl monomer and the vinyl cyan monomer in the heating step.

The amount of the continuously introduced aromatic vinyl monomer may be 15 to 50 wt%, 20 to 45 wt%, or 28 to 43 wt% based on the total weight of the aromatic vinyl monomers charged into the copolymer. By weight to 28% by weight to 43% by weight. When the above-mentioned range is satisfied, it is possible to balance a vinyl cyanide monomer in which the content capable of participating in polymerization increases with the lapse of the polymerization time, so that a copolymer having a uniform composition throughout the polymerization can be produced.

The aromatic vinyl monomer may be continuously introduced at a constant rate for 60 to 300 minutes, 120 to 280 minutes, or 180 to 260 minutes, and the continuous introduction is preferably performed at a constant rate for 180 to 260 minutes. When the above-mentioned range is satisfied, it is possible to balance a vinyl cyanide monomer in which the content capable of participating in polymerization increases with the lapse of the polymerization time, so that a copolymer having a more uniform composition throughout the polymerization can be produced.

The method of producing a copolymer according to an embodiment of the present invention preferably employs suspension polymerization.

The copolymer produced by the process for producing a copolymer according to an embodiment of the present invention comprises an aromatic vinyl monomer-derived unit and a vinyl cyan monomer-derived unit, and the vinyl cyanide The standard deviation of the content of monomer-derived units is 0.7 or less.

Specifically, the standard deviation of the copolymer obtained when the polymerization conversion ratios are 3%, 13%, 20%, 30%, 45%, 60%, 80%, 85%, 90%, 92% and 95% And the content of the vinyl-cyan monomer-derived units may be measured, and the standard deviation of these units may be calculated.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Example  One

140 parts by weight of ion-exchanged water, 0.186 parts by weight of 1,1'-azobis (cyclohexane-1-carbonitrile) (trade name: V-40, manufacturer: Wako) as an initiator, 1.3 parts by weight of tricalcium phosphate , 0.08 part by weight of t-dodecyl mercaptan as a molecular weight regulator, and 29 parts by weight of acrylonitrile were charged, and 51 parts by weight of styrene was added thereto before the polymerization was started. After raising the temperature of the reactor to 92 占 폚 (at a polymerization conversion of 3%), 20 parts by weight of styrene was continuously fed at a constant rate for 130 minutes. After completion of the continuous introduction of styrene, the polymerization was further carried out for 230 minutes, and the polymerization was terminated. Then, formic acid was added to the reactor to adjust the pH of the polymerization solution to 2.5, followed by washing with water, dehydration and drying to prepare a copolymer.

Example  2

A copolymer was prepared in the same manner as in Example 1, except that 20 parts by weight of styrene was continuously added at a constant rate for 260 minutes and further polymerization was carried out for 100 minutes after completion of the continuous introduction of styrene.

Example  3

41 parts by weight of styrene was added before the initiation of polymerization, 30 parts by weight of styrene was continuously fed at a constant rate for 260 minutes, and the polymerization was further carried out for 100 minutes after the continuous introduction of styrene was completed. To prepare a copolymer.

Example  4

Styrene (41 parts by weight) was added before the initiation of polymerization, the temperature of the reactor was raised, and polymerization was carried out for 15 minutes (at a polymerization conversion rate of 10%). Then, 30 parts by weight of styrene was continuously fed at a constant rate for 260 minutes, Copolymer was prepared in the same manner as in Example 1, except that the polymerization was further carried out for 85 minutes after the continuous introduction was completed.

division Before polymerization After warming up Styrene feed
(Parts by weight) Starting point of continuous injection of styrene
(Polymerization conversion rate) Continuous Styrene Feed
(Parts by weight) Injection time
(minute) Example 1 51 3% 20 130 Example 2 51 3% 20 260 Example 3 41 3% 30 260 Example 4 41 10% 30 260

Comparative Example  One

140 parts by weight of ion-exchanged water, 0.186 parts by weight of 1,1'-azobis (cyclohexane-1-carbonitrile) (trade name: V-40, manufacturer: Wako) as an initiator, 1.3 parts by weight of tricalcium phosphate 0.08 parts by weight of t-dodecyl mercaptan as a molecular weight regulator, and 29 parts by weight of acrylonitrile were charged, and 71 parts by weight of styrene was added thereto. After the temperature of the reactor was raised to 92 占 폚, polymerization was further performed for 360 minutes, and the polymerization was terminated. Then, formic acid was added to the reactor to adjust the pH of the polymerization solution to 2.5, followed by washing with water, dehydration and drying to prepare a copolymer.

Comparative Example  2

140 parts by weight of ion-exchanged water, 0.186 parts by weight of 1,1'-azobis (cyclohexane-1-carbonitrile) (trade name: V-40, manufacturer: Wako) as an initiator, 1.3 parts by weight of tricalcium phosphate , 0.08 part by weight of t-dodecyl mercaptan as a molecular weight regulator, and 29 parts by weight of acrylonitrile were introduced, and 41 parts by weight of styrene was added thereto before the polymerization was started. After raising the temperature of the reactor to 92 ° C, polymerization was carried out for 20 minutes (polymerization conversion ratio: 13%), and 30 parts by weight of styrene was continuously fed at a constant rate for 260 minutes. After the continuous introduction of styrene was completed, the polymerization was further performed for 80 minutes, and the polymerization was terminated. Then, formic acid was added to the reactor to adjust the pH of the polymerization solution to 2.5, followed by washing with water, dehydration and drying to prepare a copolymer.

Comparative Example  3

140 parts by weight of ion-exchanged water, 0.186 parts by weight of 1,1'-azobis (cyclohexane-1-carbonitrile) (trade name: V-40, manufacturer: Wako) as an initiator, 1.3 parts by weight of tricalcium phosphate , 0.08 part by weight of t-dodecyl mercaptan as a molecular weight regulator, and 29 parts by weight of acrylonitrile were introduced, and 41 parts by weight of styrene was added thereto before the polymerization was started. After elevating the temperature of the reactor to 92 占 폚, polymerization was carried out for 30 minutes (polymerization conversion rate: 20%), and 30 parts by weight of styrene was continuously fed at a constant rate for 260 minutes. After completion of the continuous introduction of styrene, further polymerization was carried out for 70 minutes, and the polymerization was terminated. Then, formic acid was added to the reactor to adjust the pH of the polymerization solution to 2.5, followed by washing with water, dehydration and drying to prepare a copolymer.

Comparative Example  4

140 parts by weight of ion-exchanged water, 0.186 parts by weight of 1,1'-azobis (cyclohexane-1-carbonitrile) (trade name: V-40, manufacturer: Wako) as an initiator, 1.3 parts by weight of tricalcium phosphate , 0.08 part by weight of t-dodecyl mercaptan as a molecular weight regulator, and 29 parts by weight of acrylonitrile were introduced, and 41 parts by weight of styrene was added thereto before the polymerization was started. After raising the temperature of the reactor to 92 캜, polymerization was carried out for 60 minutes (polymerization conversion rate: 30%), and 30 parts by weight of styrene was continuously fed at a constant rate for 260 minutes. After completion of the continuous introduction of styrene, the polymerization was further carried out for 40 minutes, and the polymerization was terminated. Then, formic acid was added to the reactor to adjust the pH of the polymerization solution to 2.5, followed by washing with water, dehydration and drying to prepare a copolymer.

Test Example

The difference in content and the standard deviation of the acrylonitrile-derived units in the final products of the copolymers prepared in Examples and Comparative Examples and the intermediate products were calculated by the methods described below and are shown in Table 2 below.

* Difference in the content of acrylonitrile-derived units: The maximum value among the content of acrylonitrile-derived units in the copolymer as a final product and the content of acrylonitrile-derived units in the copolymer, which is an intermediate product obtained within the polymerization conversion ratio shown in Table 2 Respectively. And we calculated the difference between them.

* Standard deviation of acrylonitrile-derived units: 30% (60 minutes after the temperature rise), 20% (elapsed after warming), 3% (immediately after heating), 13% 90% (temperature 240 minutes after warming), 45% (90 minutes after warming), 60% (after 120 minutes after heating), 80% The content of acrylonitrile-derived units in the copolymer obtained at the time point of 92% (after 300 minutes from the temperature rise) and 95% (after 360 minutes from the temperature rise) was measured and their standard deviation was calculated.

division Polymerization Conversion (%) Standard Deviation 0 to 25 25 to 50 50 to 75 75 ~ 95 Example 1 2.36 1.57 1.35 1.00 0.65 Example 2 1.04 1.09 0.42 0.45 0.55 Example 3 0.25 0.14 0.40 0.65 0.30 Example 4 0.30 0.19 0.55 1.01 0.51 Comparative Example 1 2.45 2.22 1.57 0.75 0.90 Comparative Example 2 0.45 0.27 0.49 1.61 0.69 Comparative Example 3 0.44 0.19 0.55 1.86 0.71 Comparative Example 4 - 0.17 0.20 2.07 0.81

Referring to Table 2, in the case of the copolymers of Example 1 and Example 2, the difference in the content of acrylonitrile-derived units in the final product from the content of acrylonitrile-derived units in the intermediate product Respectively. Also, since the standard deviation was low, it was confirmed that a copolymer having a uniform composition was produced.

In the case of the copolymers of Example 3 and Example 4, the difference in the content of acrylonitrile-derived units in the final product from the content of acrylonitrile-derived units in the intermediate product increased as the polymerization conversion rate increased to 50% or more , And the standard deviation was significantly lower than those of Example 1, Example 2, Comparative Example 1 and Comparative Example 2, it was confirmed that a copolymer having a uniform composition was produced.

In the case of Comparative Example 1, since styrene was added all at a time before the start of polymerization, the difference between the content of acrylonitrile-derived units in the final product and the content of acrylonitrile-derived units in the intermediate product was larger than those of Examples 1 to 3, It was confirmed that a copolymer having a uniform composition was not produced because the deviation was high.

In the case of Comparative Examples 2 to 4 in which styrene was continuously fed at the time when the polymerization conversion ratios were 13%, 20%, and 30%, the content of acrylonitrile-derived units in the final product in the section where the polymerization conversion rate was 75 to 95% And the content of acrylonitrile-derived units in the intermediate product were remarkably increased. As a result, the standard deviation was increased, and it was confirmed that a copolymer having a uniform composition was not produced.

Claims (12)

Introducing an aromatic vinyl monomer and a vinylcyanide monomer into a reactor prior to initiation of polymerization;
Heating the reactor; And
And a step of continuously polymerizing the aromatic vinyl monomer at a constant rate at a time when the polymerization conversion rate is 10% or less in the reactor which has been heated up after the temperature rise is completed.
The method according to claim 1,
Wherein the step of polymerizing is a step of continuously polymerizing the aromatic vinyl-based monomer in the reactor at a constant rate at a polymerization conversion of 1 to 10%.
The method according to claim 1,
Wherein the step of polymerizing is a step of continuously polymerizing the aromatic vinyl-based monomer in the reactor at a constant rate at a polymerization conversion of 1 to 5%.
The method according to claim 1,
Wherein the amount of the continuously introduced aromatic vinyl monomer is 15 to 50% by weight based on the total weight of the aromatic vinyl monomers charged in the copolymer production method.
The method according to claim 1,
Wherein the amount of the continuously introduced aromatic vinyl monomer is 28 to 43% by weight based on the total weight of the aromatic vinyl monomers charged into the copolymer.
The method according to claim 1,
Wherein the polymerizing step is a step of continuously polymerizing the aromatic vinyl-based monomer in the reactor at a constant rate for 60 to 300 minutes.
The method according to claim 1,
Wherein the step of polymerizing is a step of polymerizing the aromatic vinyl-based monomer continuously charged into the reactor at a constant rate for 180 to 260 minutes.
The method according to claim 1,
Wherein the step of raising the temperature is a step of raising the temperature of the reactor to 80 to 105 ° C.
The method according to claim 1,
Wherein the aromatic vinyl monomer and the vinyl cyan monomer are not added in the step of raising the temperature.
The method according to claim 1,
Wherein the weight ratio of the aromatic vinyl monomer to the vinyl cyan monomer added to the copolymer is 85:15 to 60:40.
The method according to claim 1,
Wherein the polymerization is a suspension polymerization.
A copolymer produced by the production process according to any one of claims 1 to 11,
An aromatic vinyl-based monomer-derived unit, and a vinylcyanide-based monomer-derived unit,
Wherein the standard deviation of the content of vinylcyanide monomer-derived units in the copolymer produced at the respective polymerization conversion rates is 0.7 or less.