KR20160131659A

KR20160131659A - Separation method of organic zinc catalyst

Info

Publication number: KR20160131659A
Application number: KR1020150064552A
Authority: KR
Inventors: 김성경; 박승영; 조윤기; 박종서; 이진우; 이준의
Original assignee: 주식회사 엘지화학
Priority date: 2015-05-08
Filing date: 2015-05-08
Publication date: 2016-11-16
Also published as: KR101794913B1

Abstract

~The present invention relates to a method for separating an organic zinc catalyst. The method for separating an organic zinc catalyst comprises the following steps of: adding a coagulant ncluding water to a polyalkylene carbonate resin solution including a polyalkylene carbonate resin, and a remaining organic zinc catalyst; and centrifuging the polyalkylene carbonate resin mixture.

Description

{SEPARATION METHOD OF ORGANIC ZINC CATALYST}

The present invention relates to a method for separating organic zinc catalysts. More particularly, the present invention relates to an organic zinc catalyst separation method capable of improving the separation efficiency of an organic zinc catalyst while preventing contamination of polyalkylene carbonate, which is a reaction product, in a polyalkylene carbonate resin production process using an organic zinc catalyst .

Since the Industrial Revolution, mankind has built a modern society by consuming a large amount of fossil fuels, while increasing the atmospheric carbon dioxide concentration and further promoting this increase by environmental destruction such as deforestation. Since global warming is caused by the increase of greenhouse gases such as carbon dioxide in the atmosphere and freon or methane, it is very important to reduce the atmospheric concentration of carbon dioxide which contributes to global warming. Are being carried out on a global scale.

Among them, the copolymerization reaction of carbon dioxide and epoxide found by Inoue et al. Is expected as a reaction to solve the problem of global warming, and it is actively studied not only in terms of fixation of chemical carbon dioxide but also in the use of carbon dioxide as carbon resources . Particularly, in recent years, the polyalkylene carbonate resin obtained by the polymerization of carbon dioxide and epoxide is widely regarded as a kind of biodegradable resin.

Various catalysts for the production of such polyalkylene carbonate resins have been studied and proposed, and organic zinc catalysts such as zinc glutarate catalysts having zinc and dicarboxylic acid bonded thereto are known as typical catalysts.

However, such an organic zinc catalyst has a fine crystalline particle shape and is uniformly dispersed in the polymerization solution after the polymerization reaction of the polyalkylene carbonate resin in solution is completed. Since the organic zinc catalyst is small in particle size, it can be easily separated by filtration or centrifugation There was a difficult limit.

In order to separate an organic zinc catalyst dispersed evenly in a solution state, there has been proposed a method of agglomerating organic zinc catalyst particles by using a polymer capable of adsorbing on the surface of the organic zinc catalyst particle. However, the polyalkylene carbonate And the like.

Accordingly, there is a need to develop an organic zinc catalyst separation method capable of improving the separation efficiency of an organic zinc catalyst while preventing contamination of polyalkylene carbonate as a reaction product.

Disclosed herein is an organic zinc catalyst separation method capable of improving the separation efficiency of an organic zinc catalyst while preventing contamination of polyalkylene carbonate, which is a reaction product, in a polyalkylene carbonate resin production process using an organic zinc catalyst .

In the present specification, the method includes mixing a polyalkylene carbonate resin solution containing a polyalkylene carbonate resin and a residual organic zinc catalyst with a flocculant containing water; And centrifuging the polyalkylene carbonate resin mixture to separate the organic zinc catalyst.

The organic zinc catalyst separation method according to a specific embodiment of the present invention will be described in more detail below.

According to an embodiment of the present invention, there is provided a method of producing a polyalkylene carbonate resin, comprising: mixing a polyalkylene carbonate resin solution containing a polyalkylene carbonate resin and a residual organic zinc catalyst with a flocculant containing water; And centrifuging the polyalkylene carbonate resin mixture to obtain an organic zinc catalyst separation method.

The present inventors have found that, by using the above-described specific organic zinc catalyst separation method, a polyalkylene carbonate resin is contaminated or decomposed by adding a small amount of a flocculant containing water which can be used as a solvent in a polyalkylene carbonate resin production process And it is possible to induce cohesion between the organic zinc catalyst particles by interfering with the interaction between the organic zinc catalyst particles and the polyalkylene carbonate resin.

In particular, by adding a coagulant to a solution of a polyalkylene carbonate resin containing a polyalkylene carbonate resin and a residual organic zinc catalyst and then centrifuging, the aggregation between the organic zinc catalysts contained in the polyalkylene carbonate resin solution is maximized, By passing the centrifuged polyalkylene carbonate resin solution through the filter, it was confirmed that a large amount of the organic zinc catalyst could be separated in a short time.

Specifically, the organic zinc catalyst separation method may include mixing a flocculant containing water in a polyalkylene carbonate resin solution containing a polyalkylene carbonate resin and a residual organic zinc catalyst.

The flocculant may include water as a sedimentation accelerator which is added to the liquid to gather a few large solid particles suspended in the liquid to form a slightly larger lump. The coagulant may further include an alcohol, a ketone, an ester compound, or a mixture of two or more thereof.

Examples of the alcohol compound used as the coagulant include, but are not limited to, monohydric alcohols such as methanol, ethanol, isopropanol and butanol, and polyhydric alcohols such as glycerol and ethylene glycol.

Examples of the ketone include, but are not limited to, acetone and butanone. Examples of the ester compound include ethyl acetate and butyl acetate.

Specifically, the content of the flocculant may be 0.01 wt% to 1 wt%, or 0.05 wt% to 0.5 wt%, or 0.1 wt% to 0.3 wt% based on the weight of the polyalkylene carbonate resin mixture. If the amount of the flocculant is excessively increased by more than 1% by weight based on the weight of the polyalkylene carbonate resin mixture, an additional process is required to separate a large amount of water from the polyalkylene carbonate resin mixture, .

The organic zinc catalyst may include a zinc dicarboxylate compound. Specifically, the zinc dicarboxylate compound may include a zinc salt of an aliphatic dicarboxylate having 3 to 20 carbon atoms or a zinc salt of an aromatic dicarboxylate having 8 to 40 carbon atoms.

Examples of the aliphatic dicarboxylate having 3 to 20 carbon atoms include, but are not limited to, glutarate, malonate, succinate, adipate and the like. The aromatic dicarboxylate having 8 to 40 carbon atoms Examples of the aryl carboxylate include, but are not limited to, terephthalate, isophthalate, homophthalate or phenyl glutarate. From the standpoint of the activity of the organic zinc catalyst, Rutarate can be used.

The dicarboxylate may be an aliphatic dicarboxylic acid having 3 to 20 carbon atoms such as dicarboxylic acid corresponding thereto, for example, glutaric acid, malonic acid, succinic acid or adipic acid, terephthalic acid, isophthalic acid, Aromatic dicarboxylic acids having 8 to 40 carbon atoms such as phthalic acid or phenylglutaric acid, and may be formed by the reaction of these dicarboxylic acids with zinc.

The organic zinc catalyst may include particles having an average particle diameter of 0.5 m or less and a standard deviation of particle diameter of 0.04 m or less. Specifically, the organic zinc catalyst may be in the form of a uniform particle having an average particle diameter of 0.5 m or less, or 0.1 to 0.4 m, or 0.2 to 0.4 m, a standard deviation of 0.04 m or less, or a particle diameter of 0.01 to 0.03 m .

Thus, as the organic zinc catalyst has a fine and uniform particle size, the organic zinc catalyst may have a surface area of 1.8 m 2 / g or more, or 1.8 to 2.5 m 2 / g. As a result, the organic zinc catalyst may exhibit improved activity by increasing the contact area with the reactant during the production of the polyalkylene carbonate resin.

Before the step of mixing the polyalkylene carbonate resin solution containing the polyalkylene carbonate resin and the remaining organic zinc catalyst with the flocculant containing water, the monomers containing the cyclic ether compound and the carbon dioxide are dissolved in the liquid phase And may further comprise a step of polymerizing.

In the step of subjecting the monomer containing cyclic ether compound and carbon dioxide to liquid phase polymerization in the presence of the organic zinc catalyst, the organic zinc catalyst may be used as a heterogeneous catalyst, and the polymerization step proceeds to liquid phase polymerization in a solvent . As a result, the heat of reaction can be appropriately controlled and the molecular weight or viscosity of the polyalkylene carbonate resin to be obtained can be controlled easily.

Examples of the solvent used in the liquid phase polymerization are not particularly limited, and examples thereof include methylene chloride, ethylene dichloride, trichloroethane, tetrachloroethane, chloroform, acetonitrile, propionitrile, dimethylformamide, N- Methyl-2-pyrrolidone, dimethylsulfoxide, nitromethane, 1,4-dioxane, hexane, toluene, tetrahydrofuran, methyl ethyl ketone, methylamine ketone, methyl isobutyl ketone, acetone, cyclohexanone, trichloro It is possible to use ethylene, methyl acetate, vinyl acetate, ethyl acetate, propyl acetate, butylolactone, caprolactone, nitropropane, benzene, styrene, xylene and methyl propasol or a mixture of two or more thereof, Preferably, by using dichloromethane or dichloroethane as a solvent, the progress of the polymerization reaction is promoted More effectively.

Examples of the cyclic ether compound include, but are not limited to, alkylene oxides having 2 to 20 carbon atoms, which are substituted or unsubstituted with halogen or an alkyl group having 1 to 5 carbon atoms; A cycloalkylene oxide having 4 to 20 carbon atoms substituted or unsubstituted with halogen or an alkyl group having 1 to 5 carbon atoms; Styrene oxide having 8 to 20 carbon atoms which is substituted or unsubstituted with halogen or an alkyl group having 1 to 5 carbon atoms; Or a mixture of two or more of them may be used, and an alkylene oxide having 2 to 20 carbon atoms, which is preferably substituted or unsubstituted with halogen or an alkyl group having 1 to 5 carbon atoms, may be used.

Specific examples of the alkylene oxide having 2 to 20 carbon atoms which is substituted or unsubstituted with the halogen or the alkyl group having 1 to 5 carbon atoms include ethylene oxide, propylene oxide, butene oxide, pentene oxide, hexene oxide, octene oxide, But are not limited to, oxides, tetradecene oxide, hexadecene oxide, octadecene oxide, butadiene monoxide, 1,2-epoxy-7-octene, epifluorohydrin, epichlorohydrin, epibromohydrin, isopropylglycidyl Ether, butyl glycidyl ether, t-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, and the like.

Examples of the cycloalkylene oxide having 4 to 20 carbon atoms substituted or unsubstituted with the halogen or the alkyl group having 1 to 5 carbon atoms include cyclopentene oxide, cyclohexene oxide, cyclooctene oxide, cyclododecene oxide, alpha-pinene oxide, 2,3-epoxy norbornene, limonene oxide, dieldrin, and the like.

Examples of the styrene oxide having 8 to 20 carbon atoms which is substituted or unsubstituted with the halogen or the alkyl group having 1 to 5 carbon atoms include 2,3-epoxypropylbenzene, styrene oxide, phenylpropylene oxide, stilbene oxide, , Dichlorostilbene oxide, 1,2-epoxy-3-phenoxypropane, benzyloxymethyloxirane, glycidyl-methylphenyl ether, chlorophenyl-2,3-epoxypropyl ether, epoxypropylmethoxyphenyl ether, Phenyl glycidyl ether, and glycidyl naphthyl ether.

The solvent may be used in a weight ratio of 1: 0.5 to 1: 100, or 1: 1 to 1:10, relative to the cyclic ether compound.

At this time, if the ratio is less than 1: 0.5, the solvent will not function properly as a reaction medium, and it may be difficult to take advantage of the above-mentioned solution polymerization. If the ratio is more than 1: 100, the concentration of the cyclic ether compound and the like may be lowered, resulting in a decrease in productivity, and the molecular weight of the finally formed resin may be lowered or the side reaction may increase.

The organic zinc catalyst may be added in a molar ratio of from 1:50 to 1: 1000, or from 1:70 to 1: 600, or from 1:80 to 1: 300, based on the cyclic ether compound.

If the ratio is too small, it is difficult to exhibit sufficient catalytic activity in the liquid phase polymerization. On the other hand, when the amount is excessively large, by using an excessive amount of catalyst, the by-product may not be produced, This can happen.

The liquid phase polymerization can be carried out at a temperature of from 50 to 100 DEG C, or from 70 to 90 DEG C and at a pressure of from 15 to 50 bar, or from 20 to 40 bar for from 1 to 60 hours, or from 3 to 40 hours.

Meanwhile, other polymerization processes and conditions except for the above-mentioned conditions may be used without limitation for the usual polymerization conditions for the production of the polyalkylene carbonate resin.

The organic zinc catalyst may be dispersed in the polyalkylene carbonate resin mixture in a particulate state. Due to the interaction between the polyalkylene carbonate contained in the polyalkylene carbonate resin mixture and the organic zinc catalyst, the organic zinc catalyst can be evenly dispersed in the particulate state on the polyalkylene carbonate resin mixture. Accordingly, when a filter or a centrifugal separator is simply used without adding a coagulant, the organic zinc catalyst dispersed in a fine particle state may be difficult to separate.

In addition, the organic zinc catalyst separation method may include a step of centrifuging the polyalkylene carbonate resin mixture. Specifically, the centrifugation is carried out for 0.5 to 10 minutes at a relative centrifugal force of 1,000 G to 10,000 G, or 1,500 G to 7,000 G, or 1,800 G to 6,000 G, or 1,800 G to 3,000 G, or 4,000 G to 6,000 G, Or 0.8 minutes to 6 minutes.

The relative centrifugal force refers to a force applied when the centrifugal force progresses to a value when the centrifugal force is expressed as a ratio to the earth's gravity, and the relative centrifugal force is excessively reduced to less than 1,000 G, If the time for separation is excessively reduced to less than 0.5 minutes, the aggregation effect of the organic zinc catalyst particles by centrifugation may be reduced.

Examples of the specific method of performing the centrifugal separation are not limited and various centrifugal separation apparatus widely used in the related art can be used without limitation.

The viscosity of the polyalkylene carbonate resin mixture may be from 10 cP to 500 cP, or from 50 cP to 400 cP, or from 200 cP to 300 cP. The viscosity refers to an amount indicating the magnitude of the difficulty in the flow of the fluid, i.e., the degree of stickiness. As the viscosity of the polyalkylene carbonate resin mixture satisfies the above-mentioned range, the aggregation effect between the organic zinc catalyst particles can be improved.

If the viscosity of the polyalkylene carbonate resin mixture is too small, the process cost for separating an excessive amount of solvent may increase and the efficiency of the process may decrease. In addition, if the viscosity of the polyalkylene carbonate resin mixture is too large, the cohesive force between the catalyst particles may be reduced due to low fluidity.

In addition, the method for separating organic zinc catalyst may further include separating the precipitate containing the organic zinc catalyst after centrifuging the polyalkylene carbonate resin mixture.

Wherein the precipitate comprising the organozinc catalyst comprises an organozinc catalyst agglomerated through the centrifugation and wherein the precipitate comprising the organozinc catalyst is in the range of from 100 [mu] m to 1,000 [mu] m, or from 200 [mu] m to 800 [ It can have an average particle diameter.

The method of separating the precipitate containing the organic zinc catalyst is not limited to a specific method. For example, a separation method using a filter may be used.

On the other hand, in the step of centrifuging the polyalkylene carbonate resin mixture, the content of the organic zinc catalyst in the polyalkylene carbonate resin mixture is 0.5 wt% to 2 wt%, or 0.9 wt% to 1.2 wt% Lt; / RTI > The polyalkylene carbonate resin mixture in which the content of the organic zinc catalyst is measured means a solution before centrifugation.

Also, in the step of separating the precipitate containing the organic zinc catalyst, the content of the organic zinc catalyst in the precipitated polyalkylene carbonate resin mixture containing the organic zinc catalyst may be 0.001 to 0.3% by weight, Or 0.005 wt% to 0.2 wt%, or 0.01 wt% to 0.1 wt%.

The polyalkylene carbonate resin mixture in which the precipitate containing the organic zinc catalyst is separated means a state remaining after separating the organic zinc catalyst-containing precipitate formed after centrifugation in the polyalkylene carbonate resin mixture.

If the content of the organic zinc catalyst in the polyalkylene carbonate resin mixture in which the precipitate containing the organic zinc catalyst is separated is more than 0.3% by weight based on the zinc metal, the organic zinc catalyst is not separated through the precipitate and the polyalkylene carbonate resin mixture The separation efficiency of the organic zinc catalyst separation method can be reduced.

According to the present invention, there is provided an organic zinc catalyst separation method capable of improving the separation efficiency of an organic zinc catalyst while preventing contamination of a polyalkylene carbonate, which is a reaction product, in a polyalkylene carbonate resin production process using an organic zinc catalyst .

The invention will be described in more detail in the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

< Manufacturing example : Preparation of Organozinc Catalyst>

In a 250 ml round-bottomed flask, 7.93 g (0.06 mol) of glutaric acid and 0.1 ml of acetic acid were added to 100 ml of toluene and dispersed under reflux. Subsequently, the mixture was heated at a temperature of 55 캜 for 30 minutes, and 4.1 g (0.05 mol) of ZnO was added to 50 ml of toluene and dispersed. 25% of the dispersion was first added to the reaction mixture, and 25% of the remaining 70% was added after 1 hour to conduct the reaction. The next 25% was further added for 1 hour after the reaction was completed. Thereafter, after an elapse of 1 hour, the last 25% was added to proceed the reaction. The mixed solution was heated at 110 DEG C for 2 hours. After a white solid was formed, it was filtered, washed with acetone / ethanol and dried in a vacuum oven at 130 ° C to prepare a zinc glutarate catalyst. The zinc glutarate catalyst was found to have an average particle size of about 0.2 μm and a standard deviation of particle size of 0.02 μm.

< Example 1 to 4: Organic zinc catalyst separation method>

(1) Polymerization of polyethylene carbonate

In the glove box, 0.4 g of zinc glutarate catalyst and 8.52 g of dichloromethane were placed in a high-pressure reactor and then 8.9 g of ethylene oxide was added. Thereafter, carbon dioxide was injected into the reactor and pressurized to 30 bar. Thereafter, the polymerization reaction was carried out at 70 DEG C for 3 hours to prepare polyethylene carbonate.

(2) Separation of organozinc catalyst

After completion of the polymerization reaction, water was mixed with the polyethylene carbonate solution. At this time, the content of water was 0.2% by weight with respect to the mixture. Then, the mixture was transferred to a centrifuge tube and subjected to centrifugation using a centrifugal separator under the conditions of centrifugation described in Table 1 below. At this time, the viscosity of the mixture contained in the centrifuge tube was 240 cP and the temperature was 25 캜.

After completion of the centrifugation, the supernatant of the centrifuge tube was taken out to separate the precipitate formed on the bottom. The precipitate was found to have an average particle size of 500 mu m and a standard deviation of particle size of 640 mu m.

< Comparative Example 1 to 4: Organic zinc catalyst separation method>

(1) Polymerization of polyethylene carbonate

Polymerization was carried out in the same manner as in the above examples.

(2) Separation of organozinc catalyst

Separation of the organic zinc catalyst was carried out in the same manner as in Example except that no water was added.

< Experimental Example : Example And Comparative Example Determination of Efficiency of Organic Zinc Catalyst Separation Method>

The efficiencies of the separation methods of the organic zinc catalysts of the examples and comparative examples were measured by the following methods, and the results are shown in Table 1.

1. Zinc content (ppm, wt%)

After centrifugation of the mixture of polyethylene carbonate solution and water, a portion of the supernatant was sampled and the content of zinc metal was measured using an inductively coupled plasma (ICP) apparatus, as shown in Table 1 below.

Organic zinc catalyst separation efficiencies in Examples and Comparative Examples division Centrifugation conditions Zinc (Zn) content Relative centrifugal force (G) Time (minutes) Unit: ppm Unit: wt% Example 1 2,000 3 377.49 0.03 Example 2 5,000 One 631.07 0.06 Example 3 5,000 3 276.99 0.04 Example 4 5,000 5 206.94 0.02 Reference Example 1 0 0 11,200.08 1.12 Comparative Example 1 2,000 3 8,813.67 0.88 Comparative Example 2 5,000 One 8,408.89 0.84 Comparative Example 3 5,000 3 7,930.25 0.79 Comparative Example 4 5,000 5 4,116.29 0.41 Reference Example 2 0 0 10,038.16 1.00

* Reference Example 1: The zinc content before centrifugation in the above example

Reference Example 2: In the above Comparative Example, the zinc content before centrifugation

As shown in Table 1, in the case of the organic zinc catalyst separation method of Examples 1 to 4, water was added as a flocculant, and the content of zinc contained in the mixture before centrifugation was 11,200.08 ppm (Reference Example 1 ), It can be confirmed that the centrifugation is greatly reduced to 650 ppm or less after centrifugation.

On the other hand, in the case of the organic zinc catalyst separation method of Comparative Examples 1 to 4, the water content was not added and the content of zinc contained in the mixture before centrifugation was 10,038.16 ppm (Reference Example 2) 4000 ppm to 9,000 ppm, as compared with the above-mentioned Examples.

Thus, it can be confirmed that the addition of a small amount of coagulant such as water to the polymerization solution can precipitate easily through agglomeration of the catalyst particles contained in the polymerization solution as in the above embodiment.

On the other hand, when Example 1 and Example 3 were compared, it was confirmed that the content of zinc was 377.49 ppm and the relative centrifugal force was higher than 276.99 ppm of Example 3 having 5,000 G in the case of Example 1 having a relative centrifugal force of 2,000 G . Accordingly, it can be confirmed that the smaller the relative centrifugal force, the higher the removal efficiency of the catalyst particles.

In the case of Example 4 in which the centrifugation was performed for 5 minutes, the content of zinc was 206.94 ppm, and the centrifugation was carried out for 1 minute. It can be confirmed that it is smaller than 276.99 ppm of Example 3 in which separation was performed. Accordingly, it can be seen that the efficiency of separating the catalyst particles is improved as the centrifugation time is increased.

Claims

Mixing a polyalkylene carbonate resin solution containing a polyalkylene carbonate resin and a residual organic zinc catalyst with a flocculant containing water; And
And centrifuging the polyalkylene carbonate resin mixture.

The method according to claim 1,
Wherein the content of the flocculant is 0.01 wt% to 1 wt% based on the weight of the polyalkylene carbonate resin mixture.

The method according to claim 1,
Wherein the polyalkylene carbonate resin mixture has a viscosity of 10 cP to 500 cP.

The method according to claim 1,
Wherein the content of the organic zinc catalyst in the polyalkylene carbonate resin mixture is 0.5 wt% to 2 wt% based on the zinc metal.

The method according to claim 1,
Wherein the centrifugation is carried out at a relative centrifugal force of 1,000 G to 10,000 G for 0.5 to 10 minutes.

The method according to claim 1,
Wherein the organic zinc catalyst comprises a zinc dicarboxylate compound.

The method according to claim 6,
The zinc dicarboxylate compound may be a zinc dicarboxylate compound,
A zinc salt of an aliphatic dicarboxylate having 3 to 20 carbon atoms or a zinc salt of an aromatic dicarboxylate having 8 to 40 carbon atoms.

The method according to claim 6,
Wherein the zinc dicarboxylate compound is zinc glutarate.

The method according to claim 1,
Wherein the organic zinc catalyst comprises particles having an average particle diameter of 0.5 mu m or less and a standard deviation of particle diameter of 0.04 mu m or less.

The method according to claim 1,
Wherein the organic zinc catalyst has a surface area of at least 1.8 m < 2 > / g.

The method according to claim 1,
Wherein the coagulant further comprises at least one compound selected from the group consisting of alcohols, ketones, and esters.

The method according to claim 1,
Wherein the organic zinc catalyst is dispersed in the polyalkylene carbonate resin mixture in a particulate state.

The method according to claim 1,
Before the step of mixing the flocculant containing water in the polyalkylene carbonate resin solution containing the polyalkylene carbonate resin and the residual organic zinc catalyst,
Further comprising the step of liquid phase polymerization of a monomer containing a cyclic ether compound and carbon dioxide in the presence of an organic zinc catalyst.

The method according to claim 1,
After centrifuging the polyalkylene carbonate resin mixture,
Further comprising the step of separating the precipitate containing the organic zinc catalyst.

15. The method of claim 14,
Wherein the precipitate containing the organic zinc catalyst has an average particle size of from 100 mu m to 1,000 mu m.

15. The method of claim 14,
In the step of separating the precipitate containing the organic zinc catalyst,
Wherein the content of the organic zinc catalyst in the precipitated polyalkylene carbonate resin mixture is 0.001 wt% to 0.3 wt% based on the zinc metal.