KR20210070908A - Method of preparing maleimide based copolymer - Google Patents

Abstract

The present invention relates to a method for producing a maleimide-based copolymer, which comprises a step of adding a monomer mixture comprising an aromatic vinyl-based monomer and a maleimide-based monomer to an aqueous solution consisting of an aqueous solvent and a first vinyl cyanide-based monomer, followed by polymerization. An object of the present invention is to provide a manufacturing method capable of manufacturing the maleimide-based copolymer having a uniform composition throughout the polymerization.

Description

Method of producing a maleimide-based copolymer {METHOD OF PREPARING MALEIMIDE BASED COPOLYMER}

[Citation with related applications]

The present invention claims the benefit of priority based on Korean Patent Application No. 10-2019-0160503 filed on December 5, 2019, and all contents disclosed in the literature of the Korean patent application are incorporated as a part of this specification.

[Technology]

The present invention relates to a method for preparing a maleimide-based copolymer, and more particularly, to a method for preparing a maleimide-based copolymer using an aqueous solution containing an aqueous solvent and a vinyl cyanide-based monomer.

In order to increase the heat resistance of the diene-based rubber graft polymer, a method of increasing the glass transition temperature by introducing a new monomer into an aromatic vinyl-based polymer, which is a copolymer of a vinyl cyanide-based monomer and an aromatic vinyl-based monomer, is widely used. In particular, a maleimide-based copolymer, which is a copolymer of a vinyl cyanide-based monomer, an aromatic vinyl-based monomer, and a maleimide-based monomer, has a very high glass transition temperature. However, the maleimide-based monomer forms a charge transfer complex with the aromatic vinyl-based monomer to produce an alternating copolymer, which is a copolymer of the aromatic vinyl-based monomer and the maleimide-based monomer, at the initial stage of polymerization, and in the middle and late stages of polymerization Since an aromatic vinyl-based copolymer, which is a copolymer of a vinyl cyanide-based monomer and an aromatic vinyl-based monomer, and a maleimide-based copolymer are prepared, various types of polymers are prepared by one polymerization. In order to solve this problem, continuous bulk polymerization or solution polymerization is used, but it is difficult to control the polymerization temperature due to the heat of reaction, and the polymerization conversion rate is lowered due to the increase in viscosity, so a separate recovery process is required to recover unreacted monomers. .

Therefore, studies for preparing a maleimide-based copolymer having a uniform composition while being able to use suspension polymerization with a small amount of additive, easy control of reaction heat, and high polymerization conversion rate are continuing.

JP1997-176213A

The problem to be solved by the present invention is to provide a manufacturing method capable of preparing a maleimide-based copolymer having a uniform composition throughout polymerization.

In addition, the problem to be solved by the present invention is to provide a manufacturing method capable of producing a maleimide-based copolymer having a small amount of additive used, easy control of reaction heat, and high polymerization conversion rate.

In order to solve the above problems, the present invention provides an aqueous solution consisting of an aqueous solvent and a first vinyl cyanide-based monomer, and a monomer mixture including an aromatic vinylic monomer and a maleimide-based monomer is added and polymerized. A method for preparing a mid-based copolymer is provided.

According to the method for producing a maleimide-based copolymer of the present invention, it is possible to prepare a maleimide-based copolymer having a uniform composition throughout the polymerization. In addition, if suspension polymerization is applied to the method for producing the maleimide-based copolymer of the present invention, a maleimide-based copolymer having a small amount of additives, easy control of the reaction heat, and a high polymerization conversion rate can be prepared.

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

The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

Definition of Terms

As used herein, the term 'first and second vinyl cyanide monomers' may be at least one selected from the group consisting of acrylonitrile, methacrylonitrile, phenylacrylonitrile and α-chloroacrylonitrile, Among these, acrylonitrile is preferable. The unit derived from the vinyl cyanide monomer may be a vinyl cyanide monomer unit.

As used herein, the term 'aromatic vinyl monomer' may be at least one selected from the group consisting of styrene, α-methyl styrene, α-ethyl styrene, and p-methyl styrene, of which styrene is preferable. The unit derived from the aromatic vinyl-based monomer may be an aromatic vinyl-based monomer unit.

As used herein, the term 'maleimide-based monomer' refers to maleimide, N-methyl maleimide, N-cyclohexyl maleimide, N-phenyl maleimide, N-(4-chlorophenyl) maleimide, and 2-methyl- It may be at least one member selected from the group consisting of N-phenyl maleimide and N-(p-methoxyphenyl) maleimide, of which N-phenyl maleimide is preferable. The unit derived from the maleimide-based monomer may be a maleimide-based monomer unit.

The term 'maleimide-based copolymer' as used herein is a copolymer of a monomer mixture comprising a vinyl cyanide monomer, an aromatic vinyl monomer and a maleimide monomer, that is, a vinyl cyanide monomer unit, an aromatic vinyl monomer unit, and It may refer to a copolymer including a maleimide-based monomer unit as an essential component.

As used herein, the term 'aromatic vinyl copolymer' may refer to a copolymer of a vinyl cyanide monomer and an aromatic vinyl monomer, that is, a copolymer composed of a vinyl cyanide monomer unit and an aromatic vinyl monomer unit.

As used herein, the term 'aqueous solvent' may be at least one selected from the group consisting of distilled water and ion-exchanged water.

As used herein, the term 'polymerization conversion (%)' may be derived by the following method.

A sample can be obtained by completely dissolving a certain amount of the maleimide-based copolymer in tetrahydrofuran, then adding methanol to obtain a precipitate, and vacuum-drying the precipitate to completely remove the solvent. The weight of the sample is measured, and the polymerization conversion rate can be calculated by substituting the weight of the sample into the following formula.

Polymerization conversion (%) = (weight of sample)/(total weight of monomers added during preparation of a certain amount of maleic copolymer) × 100

Method for producing maleimide-based copolymer

In the method for producing a maleimide-based copolymer according to an embodiment of the present invention, a monomer mixture including an aromatic vinylic monomer and a maleimide-based monomer is added to an aqueous solution consisting of an aqueous solvent and a first vinyl cyanide monomer, and polymerization is performed. including the steps of

Here, in order to increase the polymerization conversion rate of the vinyl cyanide-based monomer from the initial stage of polymerization, the aqueous solution preferably does not contain other monomers, specifically, the aromatic vinyl-based monomer.

In addition, in order to increase the polymerization conversion rate of the vinyl cyanide monomer from the initial stage of polymerization, the monomer mixture preferably includes a second vinyl cyanide monomer.

The polymerization may be suspension polymerization performed by suspending the monomer in the form of drops (hereinafter referred to as 'monomer drop') in an aqueous solvent. The monomer droplets may not agglomerate in an aqueous solvent due to the presence and stirring of the suspending agent, and polymerization may be performed in the monomer droplets.

On the other hand, since the vinyl cyanide-based monomer is partially water-soluble, the vinyl-cyanide-based monomer present in the aqueous solution and the monomer drop may move to each other and try to achieve an equilibrium state. However, since the maleimide-based monomer and the aromatic vinyl-based monomer are water-insoluble, they do not move into an aqueous solution or an aqueous solvent, and may exist only in the monomer droplets. Accordingly, when the monomer mixture containing the vinyl cyanide monomer is added in a batch to an aqueous solvent other than the aqueous solution described above and then polymerized or polymerized while continuously added, the aqueous solvent and the vinyl cyanide monomer contained in the monomer drops are in equilibrium. For this purpose, a large amount of the vinyl cyanide monomer may be transferred to an aqueous solvent. For this reason, since the polymerization is carried out in a state in which the content of the vinyl cyanide-based monomer included in the monomer drops is significantly lower than the content of the vinyl cyanide-based monomer included in the monomer mixture at the initial stage of polymerization, the maleimide-based polymer prepared in the initial stage of polymerization will contain a remarkably small amount of a vinyl cyanide-based monomer unit. In addition, as the polymerization proceeds, when the vinyl cyanide-based monomer present in the monomer drop is consumed, the vinyl cyanide-based monomer transferred to the aqueous solvent is moved back into the monomer drop and polymerization proceeds. As a result, the composition is non-uniform throughout the polymerization. One maleimide-based polymer can be prepared.

However, when the monomer mixture is added to the aqueous solution consisting of the aqueous solvent and the first vinyl cyanide monomer to form monomer droplets, the first vinyl cyanide monomer or the first vinyl cyanide monomer contained in the aqueous solution and the monomer drops. And the second vinyl cyanide monomer to achieve equilibrium, the first vinyl cyanide monomer or the first vinyl cyanide monomer and the second vinyl cyanide monomer contained in the aqueous solution move into the monomer drop, so that the polymerization initial In this case, a larger amount of vinyl cyanide-based monomer than before may be able to participate in polymerization. In addition, since the first vinyl cyanide-based monomer contained in the aqueous solution moves into the monomer droplets at a relatively early time, as a result, a maleimide-based polymer having a uniform composition throughout polymerization can be prepared.

The aqueous solution contains 100.0 parts by weight of the aqueous solvent and 1.0 to 10.0 parts by weight of the first vinyl cyanide monomer, preferably 100.0 parts by weight of the water and 3.5 to 9.5 parts by weight of the first vinyl cyanide monomer, more preferably 100.0 parts by weight of the water and 4.5 to 9.0 parts by weight of the first vinyl cyanide-based monomer may be included. When the above-described range is satisfied, the first vinyl cyanide-based monomer may be present in a dissolved state in the aqueous solution. Accordingly, in order to balance the contents of the first vinyl cyanide monomer or the first vinyl cyanide monomer and the second vinyl cyanide monomer in the aqueous solution and the monomer drop, the first vinyl cyanide monomer or the first vinyl cyanide monomer Since the monomer and the second vinyl cyanide monomer can easily migrate to the monomer droplets, a relatively large amount of the first vinyl cyanide monomer or the first vinyl cyanide monomer and the second vinyl cyanide monomer participates in the polymerization at the initial stage of polymerization. can In addition, a maleimide-based polymer having a uniform composition throughout the polymerization can be prepared.

In addition, when the monomer mixture includes the second vinyl cyanide monomer, the aqueous solution is 30.0 to 90.0 parts by weight, preferably based on 100.0 parts by weight of the sum of the first vinyl cyanide monomer and the second vinyl cyanide monomer. Preferably, the first vinyl cyanide monomer is included in an amount of 40.0 to 85.0 parts by weight, more preferably 50.0 to 85.0 parts by weight. When the above-mentioned range is satisfied, the first and second vinyl cyanide monomers can easily move into the monomer drops in order to balance the contents of the first and second vinyl cyanide monomers in the aqueous solution and the monomer drops. , a relatively large amount of the first and second vinyl cyanide-based monomers may participate in the polymerization at the initial stage of polymerization. In addition, a maleimide-based polymer having a uniform composition throughout the polymerization can be prepared.

On the other hand, based on 100 parts by weight of the total of the monomers added in the method for producing the maleimide-based polymer, 5 to 20 parts by weight of the first vinyl cyanide monomer, 40 to 55 parts by weight of the aromatic vinylic monomer, and the maleimide-based monomer 32 to 47 parts by weight of the monomer may be added to the reactor. Preferably, 7 to 18 parts by weight of the first vinyl cyanide-based monomer, 43 to 52 parts by weight of the aromatic vinyl-based monomer, and 35 to 45 parts by weight of the maleimide-based monomer may be added to the reactor.

When the second vinyl cyanide monomer is also added, 5 to 20 parts by weight of the total of the first and second vinyl cyanide monomers based on 100 parts by weight of the total of the monomers added in the method for producing the maleimide-based polymer; 40 to 55 parts by weight of the aromatic vinyl-based monomer and 32 to 47 parts by weight of the maleimide-based monomer may be added to the reactor. Preferably, a total of 7 to 18 parts by weight of the first and second vinyl cyanide monomers, 43 to 52 parts by weight of the aromatic vinyl monomer, and 35 to 45 parts by weight of the maleimide monomer may be added to the reactor. When the above conditions are satisfied, a maleimide-based polymer having excellent chemical resistance, processability, and heat resistance may be prepared.

The continuous input of the monomer mixture may be terminated at a polymerization conversion rate of 65.0 to 80.0%, and preferably at a polymerization conversion rate of 70.0 to 75.0%. If the above-mentioned range is satisfied, the monomer mixture continuously added in the later period may react with the polymer already produced to grow the polymer, and as a result, a maleimide-based copolymer having a high polymerization conversion rate may be prepared.

On the other hand, it is possible to polymerize or polymerize while adding the monomer mixture to the aqueous solution in a batch or while continuously adding it, but for process convenience and polymerization stability, it is preferable to polymerize while continuously adding it, and it is better to polymerize while continuously adding it at a constant rate desirable.

The continuous input may be performed at a constant temperature, preferably at 100.0 to 120.0 °C, and more preferably at 105.0 to 115.0 °C. When the above-mentioned range is satisfied, the polymerization rate can be kept constant throughout the polymerization.

The polymerization is preferably suspension polymerization in which the amount of additive is small, heat of reaction control is easy, and polymerization conversion is high.

In the method for producing a maleimide-based copolymer according to an embodiment of the present invention, after the continuous input of the monomer mixture is finished, so that the monomer mixture continuously added at a later stage can sufficiently participate in polymerization to grow the polymer already produced, It may further include the step of polymerization and aging.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

Examples 1 to 5

The aqueous solution shown in Table 1 below, 0.02 parts by weight of 1-di(t-butyl peroxy)cyclohexane, 1.3 parts by weight of tricalcium phosphate, and 0.1 parts by weight of t-dodecyl mercaptan were added to the reactor. The reactor was heated to 110 °C. Then, suspension polymerization was carried out while continuously introducing the first monomer mixture shown in Table 1 below at a constant rate from immediately after the reactor temperature was raised until the polymerization conversion reached 70%.

After the continuous input of the first monomer mixture was terminated, polymerization and aging were performed for 180 minutes, and then polymerization was terminated. Then, formic acid was added to the reactor so that the pH of the polymerization slurry became 2.5, and then washed with water, dehydrated and dried to prepare a copolymer in the form of beads.

Comparative Example 1

The aqueous solvent described in Table 2 below, 0.02 parts by weight of 1-di(t-butyl peroxy)cyclohexane, 1.3 parts by weight of tricalcium phosphate, and 0.1 parts by weight of t-dodecyl mercaptan were added to the reactor. After raising the temperature of the reactor to 110° C., the second monomer mixture described in Table 2 below was batch-injected, followed by suspension polymerization for 360 minutes, and polymerization was terminated. Then, formic acid was added to the reactor so that the pH of the polymerization slurry became 2.5, and then washed with water, dehydrated and dried to prepare a copolymer in the form of beads.

Comparative Example 2

Into the reactor, the aqueous solvent described in Table 2, 0.02 parts by weight of 1,1-di(t-butyl peroxy)cyclohexane, 1.3 parts by weight of tricalcium phosphate, and 0.1 parts by weight of t-dodecyl mercaptan were added to the reactor. The reactor was heated to 110 °C. Then, suspension polymerization was carried out while continuously introducing the third monomer mixture shown in Table 2 below at a constant rate from immediately after the reactor temperature was raised until the polymerization conversion reached 70%.

After the continuous input of the third monomer mixture was terminated, polymerization and aging were performed for 180 minutes, and then polymerization was terminated.

Then, formic acid was added to the reactor so that the pH of the polymerization slurry became 2.5, and then washed with water, dehydrated and dried to prepare a copolymer in the form of beads.

Comparative Example 3

The aqueous solution shown in Table 2 below, 0.02 parts by weight of 1,1-di(t-butyl peroxy)cyclohexane, 1.3 parts by weight of tricalcium phosphate, and 0.1 parts by weight of t-dodecyl mercaptan were added to the reactor. The reactor was heated to 110 °C. Then, suspension polymerization was carried out while continuously introducing the third monomer mixture shown in Table 2 below at a constant rate from immediately after the reactor temperature was raised until the polymerization conversion reached 70%.

After the continuous input of the third monomer mixture was terminated, polymerization and aging were performed for 180 minutes, and then polymerization was terminated. Then, formic acid was added to the reactor so that the polymerization slurry had a pH of 2.5, and then washed with water, dehydrated and dried to prepare a copolymer in the form of beads.

Experimental Example 1

The physical properties of the maleimide-based copolymers prepared in Examples and Comparative Examples were calculated by the method described below and shown in Tables 1 and 2 below.

(1) Final polymerization conversion (%): 4 g of the maleimide-based copolymer was completely dissolved in tetrahydrofuran. Then, methanol was thrown in, and the precipitate was obtained. The obtained precipitate was dried in vacuo to completely remove the solvent to obtain a sample. The weight of the sample was measured, and the final polymerization conversion rate was calculated by substituting the weight of the sample into the following formula.

Final polymerization conversion (%) = (weight of sample) / (total weight of monomers added during the preparation of 4 g of maleic copolymer) × 100

(2) AN unit content in the maleimide-based copolymer: Whenever the polymerization conversion rate shown in Tables 1 and 2 is reached during the manufacturing process of the maleimide-based copolymer, the maleimide-based copolymer is collected and maleimide-based copolymer is obtained. The content of acrylonitrile units in the copolymer was determined by elemental analysis.

Here, the polymerization conversion rate was calculated in the same manner as (1) final polymerization conversion rate (%).

(3) Glass transition temperature of maleimide-based copolymer: Whenever the polymerization conversion rate shown in Tables 1 and 2 is reached during the manufacturing process of the maleimide-based copolymer, the maleimide-based copolymer is collected and maleimide-based copolymer is obtained. The copolymer glass transition temperature was measured by differential scanning calorimetry.

Here, the polymerization conversion rate was calculated in the same manner as (1) final polymerization conversion rate (%).

division Example One 2 3 4 5 aqueous solution
(parts by weight) Distilled water 140.0 140.0 140.0 140.0 140.0 AN 4.2 5.6 7.0 9.8 12.0 first monomer mixture
(parts by weight) AN 7.8 6.4 5.0 2.2 0 ST 48.0 48.0 48.0 48.0 48.0 PMI 40.0 40.0 40.0 40.0 40 Maleimide-based copolymer Final polymerization conversion (%) 94.2 94.6 94.5 94.8 94.5 AN
unit
content
(weight%) polymerization
conversion rate 15 3.5 4.3 5.6 6.7 6.8 30 3.8 4.5 5.9 7.2 7.1 50 4.5 5.2 6.2 7.7 7.7 70 5.9 6.4 7.1 8.6 8.5 90 10.1 10.2 10.2 10.3 10.3 Glass
transition
Temperature polymerization
conversion rate 15 204.3 199.4 192.5 183.2 183.0 30 200.8 496.7 190.2 180.0 179.9 50 198.6 193.8 189.1 178.2 178.3 70 190.1 186.2 182.6 175.2 175.1 90 170.1 170.4 171.2 172.1 172.0 AN: acrylonitrile
ST: Styrene
PMI: N-phenylmaleimide

division comparative example One 2 3 Aqueous solvent (parts by weight) Distilled water 140.0 140.0 0 Aqueous solution (parts by weight) Distilled water 0 0 140.0 AN 0 0 7.0 ST 0 0 28 second monomer mixture
(parts by weight) AN 12.0 0 0 ST 48.0 0 0 PMI 40.0 0 0 third monomer mixture
(parts by weight) AN 0 12.0 5.0 ST 0 48.0 20.0 PMI 0 40.0 40.0 Maleimide-based copolymer Final polymerization conversion (%) 94.6 94.3 94.5 AN
unit content
(weight%) polymerization
conversion rate 15 2.3 2.2 2.2 30 2.7 2.3 2.5 50 3.3 2.9 3.1 70 5.2 4.2 5.0 90 10.2 10.1 10.2 Glass
transition
Temperature polymerization
conversion rate 15 216.4 215.8 216.0 30 209.8 213.2 212.6 50 205.5 208.1 207.4 70 194.8 199.2 198.8 90 168.3 167.7 168.1 AN: acrylonitrile
ST: Styrene
PMI: N-phenylmaleimide

Referring to Tables 1 and 2, in Examples 1 to 5, in which suspension polymerization was performed while continuously adding the first monomer mixture to an aqueous solution, Comparative Example 1 in which the second monomer mixture was collectively added to an aqueous solvent and then suspension polymerization Compared to Comparative Example 2, in which suspension polymerization was performed while continuously adding a third monomer mixture to an aqueous solvent, and Comparative Example 3, in which suspension polymerization was performed while continuously adding the third monomer mixture to an aqueous solution containing styrene and acrylonitrile, throughout the polymerization It can be seen that the maleimide-based copolymer having a small difference in the content of the acrylonitrile-based unit was prepared. In addition, since N-phenyl maleimide did not excessively participate in the polymerization during the initial and middle stages of polymerization, it was confirmed that a maleimide-based copolymer with a small difference in glass transition temperature throughout the polymerization was prepared. According to the method for producing the maleimide-based copolymer, it could be predicted that a maleimide-based polymer having a uniform composition could be prepared because the vinyl cyanide-based monomer and the maleimide-based monomer could participate in the polymerization in a certain amount throughout the polymerization.

Claims (10)

A method for producing a maleimide-based copolymer, comprising: adding a monomer mixture including an aromatic vinylic monomer and a maleimide-based monomer to an aqueous solution comprising an aqueous solvent and a first vinylcyanide-based monomer and polymerizing the mixture.
The method according to claim 1,
The monomer mixture is a method for producing a maleimide-based copolymer comprising a second vinyl cyanide-based monomer.
The method according to claim 1,
The polymerization step is a method for producing a maleimide-based copolymer that is a step of polymerization while continuously adding the monomer mixture to the aqueous solution.
The method according to claim 1,
The aqueous solution is a method for producing a maleimide-based copolymer comprising the first vinyl cyanide-based monomer in a dissolved state.
The method according to claim 1,
The aqueous solution is a method for producing a maleimide-based copolymer comprising 100.0 parts by weight of the water and 1.0 to 10.0 parts by weight of the first vinyl cyanide-based monomer.
The method according to claim 1,
The aqueous solution is a method for producing a maleimide-based copolymer comprising 100.0 parts by weight of the water and 3.5 to 9.5 parts by weight of the first vinyl cyanide-based monomer.
3. The method according to claim 2,
The aqueous solution is a maleimide-based copolymer comprising the first vinyl cyanide monomer in an amount of 30.0 to 90.0 parts by weight based on 100.0 parts by weight of the sum of the first vinyl cyanide monomer and the second vinyl cyanide monomer. manufacturing method.
3. The method according to claim 2,
The aqueous solution is a maleimide-based copolymer comprising the first vinyl cyanide monomer in an amount of 40.0 to 85.0 parts by weight based on 100.0 parts by weight of the sum of the first vinyl cyanide monomer and the second vinyl cyanide monomer. manufacturing method.
4. The method according to claim 3,
The method for producing a maleimide-based copolymer is a time point at which the continuous input of the monomer mixture is terminated when the polymerization conversion rate is 65.0 to 80.0%.
The method according to claim 1,
The polymerization is a method for producing a maleimide-based copolymer is suspension polymerization.