KR20170007947A - Preparation method of zinc-based catalyst and production method of poly(alkylene carbonate) using the catalyst - Google Patents

Abstract

The present invention relates to a method for producing a zinc-based catalyst, and to a method for producing polyalkylene carbonate using the same. More specifically, provided is a method for producing a zinc-based catalyst, which minimizes attachment of impurities onto surfaces of glass in an oven when drying and ensures reduction in a residual amount of impurities while increasing catalytic activities, compared to existing counterparts. To this end, a secondary vacuum drying process is carried out under a fixed temperature and pressure during a drying step in a method for producing a zinc-based catalyst used in the production of polyalkylene carbonate resins. Also, provided is a method for producing polyalkylene carbonate using the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a polyalkylene carbonate, and a method for producing the polyalkylene carbonate using the same. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyalkylene carbonate

The present invention relates to a process for preparing a zinc-based catalyst capable of increasing the activity of a catalyst and decreasing the content of by-products in the process for producing polyalkylene carbonate, and a process for producing polyalkylene carbonate using the same.

Polyalkylene carbonate is a non-crystalline transparent resin, unlike an aromatic polycarbonate which is a similar type of engineering plastic, exhibits biodegradability and is thermally decomposable at a low temperature, and has the advantage of being completely decomposed into carbon dioxide and water and having no carbon residue Have.

The production of the polyalkylene carbonate is carried out in the presence of a solvent such as methylene chloride, and various impurities are present in the polymerization product after polymerization.

The production process of the polyalkylene carbonate is largely divided into a polymerization process and a post-treatment process. In the post-treatment process, the residual monomers and impurities other than the polyalkylene carbonate are removed and a pelletization process is included.

On the other hand, various catalysts for producing the polyalkylene carbonate resin have been studied and proposed, and a zinc dicarboxylate-based catalyst such as a zinc glutarate catalyst in which zinc and a dicarboxylic acid are bonded is known as a typical catalyst.

Such a zinc dicarboxylate catalyst, typically a zinc glutarate catalyst, is formed by reacting a zinc precursor with a dicarboxylic acid, such as glutaric acid, and is in the form of a fine crystalline particle. However, in the case of such a crystalline particle type zinc dicarboxylate catalyst, it is generally necessary to remove a solvent such as toluene used for the synthesis after synthesis. In the past, filtration treatment with acetone was performed mainly to remove the toluene, and vacuum drying was carried out at 100 to 300 ° C for 24 to 48 hours. The reason for vacuum drying is to remove the remaining glutaric acid, which is also used to remove acetone and toluene.

When excess glutaric acid remains, not only the activity of the catalyst is deteriorated but also the polymerization selectivity is affected, so that the physical properties of the obtained polyalkylene carbonate can be lowered.

An object of the present invention is to provide a method for preparing a zinc-based catalyst capable of increasing the polymerization activity of the catalyst according to a post-process (drying process) of catalyst synthesis.

Another object of the present invention is to provide a process for producing a polyalkylene carbonate which can reduce the by-product content by improving polymerization selectivity in the production of polyalkylene carbonate by using the zinc-based catalyst having the increased polymerization activity.

The present invention relates to a process for preparing a zinc dicarboxylate catalyst by reacting a zinc precursor with a dicarboxylic acid having 3 to 20 carbon atoms in the presence of a solvent and washing the catalyst, In a process for producing a zinc-based catalyst,

The step of drying the catalyst comprises:

a) the washed catalyst is first dried under vacuum at a temperature of from 100 to 140 < 0 > C for 24 to 72 hours,

b) secondary drying the primary dried catalyst at a temperature of from 80 to 140 占 폚 and a pressure of from -1.0 to -0.5 bar for at least 24 hours to 72 hours under high vacuum;

Based catalyst, which comprises the steps of:

In the present invention, the step of drying and pulverizing the washed catalyst of the step a) under an inert gas condition before the primary drying, or the step of pulverizing the washed catalyst of the step a) before the primary drying and drying under an inert gas condition As shown in FIG.

The catalyst may comprise a powder having an average particle size of 0.1 to 10.0 micrometers. The secondary drying may be carried out two to three times.

Wherein the zinc precursor is zinc oxide (ZnO), zinc sulfate (ZnSO _4), chlorate, zinc _{(Zn (ClO 3) 2)} , zinc nitrate _{(Zn (NO 3) 2)} , zinc acetate (Zn (OAc) _2), and And zinc hydroxide (Zn (OH) ₂ ).

The dicarboxylic acid may be at least one compound selected from the group consisting of malonic acid, glutaric acid, succinic acid, adipic acid, terephthalic acid, isophthalic acid, homophthalic acid, and phenylglutaric acid.

The present invention also provides a process for producing a polyalkylene carbonate comprising the step of polymerizing an epoxide compound and carbon dioxide in the presence of the zinc-based catalyst and the solvent.

The present invention relates to a process for preparing a zinc-based catalyst for use in the production of a polyalkylene carbonate resin, wherein a second vacuum drying is carried out under a constant temperature and pressure condition in a drying step, And the remaining dicarboxylic acid can be easily removed from the product. Thus, the residual amount of dicarboxylic acid can be reduced to less than 50% of the initial concentration, thereby increasing the activity and selectivity of the catalyst.

FIG. 1 shows measured values of weight loss according to the drying time and the vacuum drying condition of Comparative Examples 2 to 3 and Example 1. FIG.
Fig. 2 shows the residual amount (the trend of decreasing the amount of glutaric acid remaining) relative to the initial amount of glutaric acid with respect to the number of drying times and the time of Comparative Examples 2 to 3 and Examples 1 to 3.

Hereinafter, the present invention will be described in more detail. 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.

Also, " comprising "as used herein should be interpreted as specifying the presence of particular features, integers, steps, operations, elements and / or components, It does not exclude the presence or addition of an ingredient.

Hereinafter, a method for producing an organic zinc catalyst according to embodiments of the present invention and a method for producing a polyalkylene carbonate resin using the same will be described in detail.

First, according to a preferred embodiment of the present invention, there is provided a process for producing a zinc dicarboxylate-based catalyst by reacting a zinc precursor with a dicarboxylic acid having 3 to 20 carbon atoms in the presence of a solvent, And drying the washed catalyst, the step of drying the catalyst comprises the steps of: a) contacting the washed catalyst at a temperature of from 100 to 140 < 0 > C for 24 to 72 hours in a vacuum B) drying the primary dried catalyst at a temperature of 80 to 140 ° C and a pressure of -1.0 to -0.5 bar for at least 24 hours to 72 hours under high vacuum, A method for producing a zinc-based catalyst is provided.

As mentioned above, generally after zinc-based catalyst such as zinc glutarate is synthesized, it is washed with acetone and filtered, and only one vacuum drying is carried out in order to remove the reaction solvent used for the synthesis.

However, the conventional method has a problem that the dicarboxylic acid sticks to the glass surface of the oven during vacuum drying, thereby increasing the amount of the byproduct and decreasing the catalytic activity.

Accordingly, in the present invention, in order to increase catalytic activity and reduce the content of by-products, the zinc precursor is reacted with a dicarboxylic acid having 3 to 20 carbon atoms in a solvent, followed by washing, followed by drying at least twice during vacuum drying. Particularly, the present invention is characterized in that a low pressure condition is maintained in the second drying process.

Here, the zinc-based catalyst in the present invention refers to a zinc dicarboxylate-based catalyst since it is prepared by the reaction of a zinc precursor and a dicarboxylic acid.

According to a preferred embodiment of the present invention, the step of drying the catalyst is carried out by first drying the washed catalyst at a temperature of 100 to 140 DEG C for 24 to 72 hours under vacuum, as in the step a) .

The equipment used in the primary and secondary drying processes may be a vacuum oven capable of maintaining temperature and pressure, but is not limited to an oven.

In addition, in the present invention, it is preferable that the washed catalyst of a) is dried and pulverized under an inert gas condition before the primary drying, or the washed catalyst of a) is pulverized before primary drying and dried under inert gas conditions Step < / RTI > The inert gas may be a commonly known gas such as Ar or N ₂ . Through the above process, not only the drying of the catalyst but also the removal of the solvent used for washing can be facilitated.

The drying conditions using nitrogen may be carried out for 24 to 72 hours under a pressure of 1 to 2 bar. The pulverizing process may be carried out by a method well known in the art. For example, a ball mill, a pulverizer, a grinder, or the like may be used. The average particle diameter of the milled catalyst may be 0.1 to 10.0 micrometers.

Further, when the temperature condition is less than 100 ° C during the primary drying, there is a problem that residual VOC and dicarboxylic acid are difficult to remove, and when the temperature exceeds 140 ° C, ZnGA may be thermally decomposed. If the drying time is less than 24 hours, there is a problem that the solvent used for preparation and washing can not be sufficiently removed. If the drying time is more than 72 hours, the organic substance in the catalyst may be carbonized by being exposed to high temperature for a long time.

And b) after the primary drying step, the primary dried catalyst is calcined at a temperature of 80 to 140 占 폚 and a pressure of -1.0 to -0.5 bar for at least 24 hours to 72 hours under vacuum Followed by a secondary drying step.

Particularly, in the step b), the secondary drying is carried out by maintaining a low pressure of -1.0 to -0.5 bar, thereby reducing the concentration of the residual dicarboxylic acid from the catalyst particles. Here, if the pressure condition is less than -1.0 bar, there is a problem that the operation cost of the equipment is excessive to maintain the high vacuum condition, and when the pressure exceeds -0.5 bar, the removal efficiency of the residual dicarboxylic acid from the catalyst drops.

When the primary drying catalyst is used at a drying temperature of less than 80 ° C, there is a problem that the drying efficiency is lowered, and when it is more than 140 ° C, there is a risk that pyrolysis may occur. If the drying time is less than 24 hours, there is a problem that the residual dicarboxylic acid is sufficiently sublimated and can not be removed. When the drying time is more than 72 hours, there is a problem that the organic material in the catalyst may be carbonized by being exposed to a high temperature for a long time.

The secondary drying may be carried out more than once, but preferably two to three times. Accordingly, the total number of times of drying of the catalyst according to the present invention may be three times or more, and more preferably four to six times, including steps a) and b).

On the other hand, before the step of drying the zinc dicarboxylate catalyst, a washing process for removing the reaction solvent may be performed.

In one preferred embodiment, the washing process may be carried out by pouring the product containing the reaction solvent into a filter and using an acetone or ketone solvent. Specific examples of the solvent used herein include at least one selected from the group consisting of acetone, ethanol, ethanol, isopropanol, and methyl ethyl ketone, but the kind thereof is not limited.

Thereafter, the present invention can perform the step of drying the above-described catalyst in order to remove the solvent used in the washing and the residual reaction solvent.

As the zinc precursor used in the step of preparing the zinc dicarboxylate-based catalyst, any zinc precursor used in the preparation of the zinc dicarboxylate-based catalyst may be used without any limitation. Specifically, the zinc precursor is zinc oxide (ZnO), zinc sulfate (ZnSO _4), chlorate, zinc _{(Zn (ClO 3) 2)} , zinc nitrate _{(Zn (NO 3) 2)} , zinc acetate (Zn (OAc) ₂ ), And zinc hydroxide (Zn (OH) ₂ ).

As the dicarboxylic acid, an arbitrary dicarboxylic acid having 3 to 20 carbon atoms may be used. Specifically, the dicarboxylic acid is an aliphatic dicarboxylic acid such as malonic acid, glutaric acid, succinic acid, and adipic acid; Aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, homophthalic acid, and phenylglutaric acid. In addition, various aliphatic or aromatic dicarboxylic acids having 3 to 20 carbon atoms may be used. In particular, in terms of the activity of the catalyst, the dicarboxylic acid may be preferably glutaric acid. In this case, the organic zinc catalyst is a zinc glutarate catalyst. In addition, a monovalent carboxylic acid such as acetic acid may be further included in the reaction of the zinc compound and the dicarboxylic acid. However, a dispersant may be added during the reaction, in which case the addition of acetic acid may be omitted. As the dispersing agent, materials well known in the field used in the production of the catalyst may be used, and the kind of the dispersing agent is not limited.

According to an embodiment of the present invention, the dicarboxylic acid may be used in the same or an excessive molar amount as the zinc precursor. Specifically, the dicarboxylic acid may be used in an amount of about 1 to 1.5 moles, or about 1.1 to 1.3 moles per mole of the zinc precursor . When the reaction proceeds while maintaining the dicarboxylic acid in the same or excess amount as the zinc precursor, the reaction may proceed slowly in the form of the dicarboxylic acid molecules or ions surrounding the uniformly dispersed zinc precursor. As a result, an organic zinc catalyst can be obtained which can cause a reaction with a dicarboxylic acid while the zinc precursor does not aggregate with each other, and exhibits a more uniform and fine particle size and improved activity.

Meanwhile, the reaction step may be conducted under a liquid medium in which a reactant containing a zinc precursor and a dicarboxylic acid and a solvent are present (for example, proceeding to a solution state in which the reactant is dissolved or dispersed in a solvent). At this time, the solution or dispersion containing the zinc precursor may be added to the solution containing the dicarboxylic acid in two or more portions. That is, a part of the solution containing the zinc precursor may be added to a solution containing the dicarboxylic acid to proceed the reaction, and then the remainder of the solution containing the zinc precursor may be divided to proceed the remaining reaction. Through this, the entire reaction step can proceed while maintaining the molar ratio of the zinc precursor and the dicarboxylic acid in the reaction system, from which an organic zinc catalyst having more uniform and fine particle size and exhibiting improved activity can be obtained . Also, the entire reaction step may be carried out while dropping the solution containing the zinc precursor uniformly in droplets in a solution containing the dicarboxylic acid.

Any organic or aqueous solvent known to be capable of uniformly dissolving or dispersing the zinc precursor and / or dicarboxylic acid may be used as the liquid medium. Specifically, the liquid medium may be one or more solvents selected from the group consisting of toluene, hexane, dimethylformamide, ethanol, and water.

The reaction of the zinc precursor and the dicarboxylic acid may be conducted at a temperature of about 50 to 130 DEG C for about 1 to 10 hours. As described above, the zinc precursor can be divided at equal intervals during the entire reaction time, and the molar ratio of reactants in the reaction system can be maintained throughout the entire reaction step.

In addition, during the reaction of the catalyst preparation, water may be produced, which can be removed by a drain process.

In the present invention, by carrying out the washing step and the drying step on the synthesized organic zinc catalyst, the preparation of a zinc-based catalyst capable of reducing the content of by-products with high catalytic activity in the production of polyalkylene carbonate is completed do.

The zinc-based catalyst thus prepared may contain a powder having an average particle diameter of 0.1 to 10.0 micrometers.

According to another embodiment of the present invention, there is provided a process for producing a polyalkylene carbonate comprising the step of polymerizing carbon dioxide with an epoxide compound in the presence of the zinc-based catalyst and the solvent.

Specifically, in the method for producing polyalkylene carbonate using the zinc-based catalyst of the present invention, a solution polymerization method may be used. In addition, the process for producing the polyalkylene carbonate of the present invention may include a monomer preparation step, a polymerization step using a zinc catalyst, a residual monomer recovery step, a catalyst removal step, a solvent removal step, a by-product removal step, have. In addition, each of the above steps can be carried out according to a method well known in the art, except that a zinc catalyst obtained using the drying method of the present invention is used, but the method is not limited thereto.

For example, the monomer preparation step is a step of preparing an epoxide compound and carbon dioxide for use in the reaction by purifying.

Therefore, it is preferable to purify the carbon dioxide, the alkylene oxide compound and the solvent used as raw materials before polymerization to maintain the moisture content at less than 10 ppm. In addition, the raw material can be passed through a column filled with a molecular sieve.

Also, the polymerization step performed following the above step is a step of putting the raw materials into a polymerization reactor and proceeding polymerization under the zinc-based catalyst to produce polyalkylene carbonate.

That is, the method for producing the polyalkylene carbonate of the present invention is not particularly limited, but can be obtained, for example, by copolymerizing the above-mentioned alkylene oxide with carbon dioxide. Or ring-opening polymerization of cyclic carbonates. The copolymerization of the alkylene oxide and carbon dioxide can be carried out in the presence of a metal complex compound such as zinc, aluminum or cobalt.

Accordingly, the polymerization step according to a preferred embodiment of the present invention is a step of supplying a catalyst, a solvent, an epoxide compound and carbon dioxide to a polymerization reactor, and then polymerizing a monomer containing an epoxide compound and carbon dioxide under a catalyst and a solvent . Such polymerization may also be continuous polymerization.

After the solution polymerization is complete, a reaction mixture is formed which comprises a polyalkylene carbonate, unreacted residual monomer, catalyst residue, solvent and byproduct. The unreacted residual monomer includes unreacted carbon dioxide and unreacted alkylene oxide.

The polymerization may be carried out at 50 to 100 ° C and 20 to 40 bar for 3 to 10 hours. In addition, since the epoxide compound, especially ethylene oxide, has a self-polymerization temperature of 90 ° C, it may be more preferable to perform the solution polymerization at a temperature of 60 to 80 ° C in order to reduce the by-product content due to autopolymerization.

Next, the present invention carries out the step of removing residual monomers and impurities from the reaction mixture in a conventional manner. Preferably, the present invention performs a catalyst removal step, a residual monomer recovery step and a solvent removal step from the reaction mixture.

Following the process, the present invention proceeds with the by-product removal step.

In solution polymerization, ethylene carbonate, which is a by-product, can be produced in the course of decomposition of the polymer into a backbite by the catalyst and heat and in the polymerization mechanism.

If the by-product remains in the resin, it adversely affects the properties of the resin such as lowering the glass transition temperature. Therefore, it is preferable to remove the by-product in the polyalkylene carbonate production process. Such by-products may include an alkylene carbonate having 1 to 5 carbon atoms, for example, ethylene carbonate.

Further, in the present invention, the step of removing by-products includes a pelletizing process. Preferably, the pelletizing step may be a step of extruding and pelletizing the reaction mixture from which the residual monomer, the catalyst residue and the solvent have been removed, and circulating methanol during the pelletization of the reaction mixture to remove by-products. The method may further include a step of cutting the polymer strands upon pelletization and then circulating methanol to remove by-products.

As the molding method when using the polyalkylene carbonate of the present invention, various known methods can be mentioned. Examples of the method for obtaining a homogeneous mixture include a method of mixing by a Hensel mixer, a ribbon blender, a blender, or the like. As the melt kneading method, a VAN Antonie Louis Barye mixer, a single-screw or twin-screw compressor, or the like can be used. The shape of the resin of the present invention is not particularly limited and may be, for example, a strand, a sheet, a flat plate, a pellet, or the like.

The method of obtaining the molded article by molding the resin of the present invention can be carried out by a known method such as injection molding, compression molding, injection compression molding, gas injection molding, foam injection molding, inflation, T die, A calendar, a blow molding process, a vacuum molding process, and a pressure molding process.

In the present invention, pelletization is used by using extrusion molding. Such a pelletizing process includes a step of putting the reaction mixture into a twin screw extruder to make it into a pellet form. And, as described above, it is preferable to produce a granular pellet having a diameter of 1 mm to 5 mm in the pelletizing step.

In the present invention, after the by-products are removed, the step of recovering the product pellets is carried out. The pellet may further include additional volatilization processes as needed prior to pellet recovery.

A preferable example of the polyalkylene carbonate obtained by the above method includes polyethylene carbonate.

In the meantime, the materials used in the solution polymerization in the present invention will be described in more detail as follows.

The epoxide compound is an alkylene oxide having 2 to 20 carbon atoms which is 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; And styrene oxide having 8 to 20 carbon atoms substituted or unsubstituted with halogen or an alkyl group having 1 to 5 carbon atoms. More preferably, the epoxide compound may include an alkylene oxide having 2 to 20 carbon atoms which is substituted or unsubstituted with halogen or an alkyl group having 1 to 5 carbon atoms.

Specific examples of the epoxide compound include ethylene oxide, propylene oxide, butene oxide, pentene oxide, hexene oxide, octene oxide, decene oxide, dodecene oxide, tetradecene oxide, hexadecene oxide, octadecene oxide, Epichlorohydrin, epibromohydrin, isopropyl glycidyl ether, butyl glycidyl ether, t-butyl glycidyl ether, 2-epoxy-7-octene, epifluorohydrin, epichlorohydrin, -Ethylhexyl glycidyl ether, allyl glycidyl ether, cyclopentene oxide, cyclohexene oxide, cyclooctene oxide, cyclododecene oxide, alpha-pinene oxide, 2,3-epoxy norbornene, limonene oxide, dieldrin , 2,3-epoxypropylbenzene, styrene oxide, phenylpropylene oxide, stilbene oxide, Propyl methoxy ether, chloropropyl methoxy ether, chloropropyl methoxy ether, chloropropyl methoxy ether, chlorostyrene benzoate, dichlorostilbene oxide, 1,2-epoxy-3-phenoxypropane, benzyloxymethyloxirane, glycidyl- Phenyl ether, biphenyl glycidyl ether, glycidyl naphthyl ether, and the like. Preferably, the epoxide compound uses ethylene oxide.

The carbon dioxide may be continuously or discontinuously introduced during the reaction but is preferably continuously introduced. In this case, the polymerization reactor may be a semi-batch type or a closed batch system good. If the carbon dioxide is not continuously supplied, the production of by-products such as polyethylene glycol increases in addition to the carbonate copolymerization reaction aimed at in the present invention, and the selectivity of the polymerization reaction can be reduced. The reaction pressure may be 5 to 50 bar, or 10 to 40 bar when carbon dioxide is continuously supplied in the polymerization.

The carbon dioxide may be added in a molar ratio of 1: 1 to 10: 1 based on the epoxide compound. More preferably, the carbon dioxide may be introduced in a molar ratio of 2: 1 to 5: 1 relative to the epoxide compound. If carbon dioxide is introduced at the above ratio, it is preferable to use a semi-batch type system as the polymerization reactor.

The zinc-based catalyst prepared above may be added in a molar ratio of 1:50 to 1: 1000, more preferably 1:70 to 1: 600, or 1:80 to 1: 300, based on the epoxide compound Lt; / RTI > If the ratio is less than 1:50, the use of an excessive amount of catalyst may lead to ineffective by-products, or the molecular weight may decrease due to the back-biting of the polymer due to heating in the presence of a catalyst and the amount of cyclic carbonate If the ratio exceeds 1: 100, the catalyst concentration is low and it is difficult to exhibit sufficient catalytic activity in solution polymerization.

Examples of the solvent used in the solution polymerization of the present invention include methylene chloride, ethylene dichloride, trichloroethane, tetrachloroethane, chloroform, acetonitrile, propionitrile, dimethylformamide, Dimethyl sulfoxide, nitromethane, 1,4-dioxane, hexane, toluene, tetrahydrofuran, methyl ethyl ketone, methylamine ketone, methyl isobutyl ketone, acetone, cyclohexanone, trichlorethylene, methyl acetate, vinyl At least one selected from the group consisting of acetate, ethyl acetate, propyl acetate, butylolactone, caprolactone, nitropropane, benzene, styrene, xylene and methyl propasol can be used. In either case, by using methylene chloride or ethylene dichloride as a solvent, the progress of the polymerization reaction can be more effectively performed.

The solvent is preferably used in a weight ratio of 1: 0.1 to 1: 100 with respect to the epoxide compound, more preferably 1: 1 to 1:10. The solvent may be methylene chloride or ethylene dichloride.

Hereinafter, preferred embodiments of the present invention will be described in detail. It should be understood, however, that these examples are for illustrative purposes only and are not to be construed as limiting the scope of the present invention.

< Manufacturing example >

(Preparation of catalyst)

5.0 kg of ZnO was dried in an oven. Then, 10 L of toluene was added to the reactor and stirred. The remaining toluene was drained and 100 L of toluene for reaction was loaded. 8.1 kg of glutaric acid and 80 ml of acetic acid (acetic acid was omitted when the dispersant was added) were put into the reactor and stirring was started. TCU was operated to raise the temperature of the reactor to 55 占 폚.

After confirming that the glutaric acid in the reactor was sufficiently dissolved in toluene, the ZnO was added three times at intervals of one hour. After a total reaction time of 3 hours, the reactor temperature was raised to 110 ° C. For smooth reflux, when the reactor reached 110 ° C and pressure started to rise, the condenser vent was opened to maintain the pressure inside the reactor. When water begins to collect at the bottom of the condenser, it periodically checks and drains the water to the bottom. At this time, the layer separation of toluene and water can be easily confirmed with the naked eye.

The reaction was continued for at least 4 hours until no more water was generated, and the amount of water collected was recorded. The reaction was allowed to cool overnight. The reaction product was drained from the reactor, 50 L of acetone was added, and the residue was removed by mixing with 15 kg of catalyst particles. The catalyst particles were separated into acetone using equipment such as a filter or a centrifuge.

< Comparative Example  1>

The catalysts synthesized were cleaned with acetone and dried naturally at room temperature and normal pressure for 24 hours. Then, the activity of the dried catalyst was measured at a polymerization temperature of 70 ° C, a reactor pressure of 30 bar, and a polymerization time of 3 hours. As a result, a catalytic activity of less than 10 g / g.cat was obtained.

< Comparative Example  2 to 3 and Example  1 to 3>

Using the catalyst particles obtained in the above Production Examples, the following steps 1 to 5 were carried out to finally obtain 15 kg of ZnGA catalysts of Comparative Examples and Examples, respectively.

1) Step 1: Particles subjected to N ₂ blowing at 1.0 to 2.5 bar for 48 hours in the process of working up 15 kg of the catalyst powder (Comparative Example 2).

2) Step 2: A sample (Comparative Example 3) which was mixed at 100 rpm for Step 1 and further dried at 70 to 90 ° C for 24 hours.

3) Step 3: The catalyst after Step 1 is first dried under vacuum at a temperature of 110 ° C to 140 ° C for 24 hours, and the primary dried catalyst is calcined at a temperature of 130 ° C and a vacuum of -0.9 bar for 48 hours under vacuum A dry sample (Example 1).

4) Steps 4 and 5: Samples in which step 3 was repeated in the same manner 1 and 2 times (Examples 2 to 3).

FIG. 1 shows measured values of weight loss according to the drying time and the vacuum drying presence / absence of Comparative Examples 2 to 3 and Example 1. FIG.

1, it can be seen that the VOC content of the particles of Example 1 is much lower than that of the particles of Comparative Examples 2 and 3. In addition, the particles of Comparative Example 3 were found to have 0.06 to 0.1 wt% of VOC removed, and the particles of Example 1 had VOC of less than 0.04 wt%.

< Experimental Example  1>

( Of polyethylene carbonate  Preparation and Catalyst Properties Test)

Comparative Examples 2 to 3 and Examples 1 to 3 were used to prepare polyethylene carbonate.

Specifically, an autoclave polymerization reactor equipped with a stirrer was used, and zinc catalyst, solvent (methylene chloride, MC), ethylene oxide (EO) and carbon dioxide of Comparative Examples 2 to 3 and Examples 1 to 3 were charged into these reactors , A polymerization temperature of 70 DEG C, 30 bar, and a polymerization time of 3 hours, respectively. The ethylene oxide (EO), carbon dioxide, and solvent were purified before polymerization to maintain the moisture content to be less than 10 ppm.

After the solution polymerization was completed under the above conditions, the catalyst residue was removed using a metal filter, the unreacted ethylene oxide was dissolved in MC under low pressure to remove, and the carbon dioxide was removed by venting. Thereafter, the MC was removed through a solvent extraction tower, and the residual reaction mixture was poured into a twin screw extruder (BA-19, manufactured by BAUTECH) and extruded to prepare granule pellets having a diameter of 3 mm.

Experimental Example 1 means that catalysts 1 (Cat-1) to 3 (Cat-3) used have different types of additives added at the time of synthesis.

The concentration of glutaric acid detected after completion of step 5 and the additive introduced in the synthesis of catalysts 1 to 3 was indicated below.

additive Glutaric acid (ppm) Step 1 (Cat-1) Acetic acid 200 Step 2 (Cat-2) Anionic surfactant 900 Step 3 (Cat-3) Alkylene glycol 500

Table 2 shows the catalytic activity results of Comparative Examples 2 to 3 and Example 1.

Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 activation
(g / g ca.t) Step 1 Step 2 Step 3 Step 4 Step 5 Catalyst 1 11 15 24 30 31 Catalyst 2 10 15 27 47 46 Catalyst 3 10 15 26 42 40

Note 1) Catalyst for ZnGA synthesis 1: Prescription of acetic acid, Catalyst 2: Prescription of anionic surfactant, Catalyst 3: Alkylene glycol prescription

From Table 2, it can be seen that the catalytic activities of Examples 1 to 3 are much better than those of Comparative Examples 2 and 3.

< Experimental Example  2>

( Of polyethylene carbonate  Preparation and Catalyst Properties Test)

Using the catalysts of Comparative Examples 2 to 3 and Example 1, polyethylene carbonate was produced under the same conditions as in Experimental Example 1. [ Thereafter, the selection of the catalyst and the content of residual glutaric acid in accordance with the number of times of drying and the time were measured by a conventional method.

(1) Selectivity

Table 3 below shows the selectivity results for the catalysts of Comparative Examples 2 to 3 and Example 1 in comparison.

EC PEC PEG-PEG PEG Selectivity (%) Number of drying times weight% Catalyst 1 Comparative Example 2 6.94 81.87 6.51 4.67 88.38 Step 1 Comparative Example 3 4.5 85.45 5.51 4.54 90.96 Step 2 Example 1 3.89 93.11 2.39 0.61 95.5 Step 3 Catalyst 2 Comparative Example 2
Step 1 3.5 91.02 3.99 1.5 95.01 Comparative Example 3 3.2 92.01 3.54 1.25 95.55 Step 2 Example 1 2.59 95.68 1.77 0.23 97.45 Step 3 Catalyst 3 Comparative Example 2
Step 1 4.5 85.45 5.51 4.54 90.96 Comparative Example 3
Step 2 3.4 91.12 3.89 1.6 95.01 Example 1
Step 3 2.46 92.4 3 2.14 95.4

From Table 3, it can be seen that the polymerization selectivity tends to increase from 95 to 97.45% as the residual vapor decreases.

(2) Residual glutaric acid content measurement

Tables 4 and 5 show the results of the measurement of the residual amount of glutaric acid and the residual amount relative to the initial amount of glutaric acid, respectively, according to the number of drying times and the times of Comparative Examples 2 to 3 and Examples 1 to 3, respectively.

Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Regidual
GA
(ppm) Step 1 Step 2 Step 3 Step 4 Step 5 Catalyst 1 790 750 510 300 200 Catalyst 2 1900 1800 1600 950 900 Catalyst 3 1000 950 600 550 500

Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Regidual
GA
(wt%) Step 1 Step 2 Step 3 Step 4 Step 5 Catalyst 1 100 94.94 64.56 37.97 25.32 Catalyst 2 100 95.00 60.00 55.00 50.00 Catalyst 3 100 95.00 60.00 55.00 50.00

From the above results, in Step 3, the residual amount of glutaric acid is reduced from 50% to 25% when steps 4 and 5 are performed, whereas 60 to 65% of glutaric acid remains after the washing in the step 3 . This is shown in FIG.

(3) catalyst selectivity with increasing number of drying times

Table 6 below shows the results of selectivity according to the number of times of drying and time increase for Examples 1 to 3.

EC PEC PEG-PEG PEG Selectivity (%) Number of drying times weight% Catalyst 1 Example 1
Step 3 3.89 93.11 2.39 0.61 95.5 Example 2
Step 4 2.99 93.38 3 0.64 96.38 Example 3
Step 5 1.59 94.26 3.6 0.55 97.86 Catalyst 2 Example 1
Step 3 3.09 95.68 2.77 0.23 98.45 Example 2
Step 4 1.34 96.2 2 0.49 98.2 Example 3
Step 5 0.75 97.51 1.5 0.24 99.01 Catalyst 3 Example 1
Step 3 2.46 92.4 3 2.14 95.4 Example 2
Step 4 2.25 94.3 2.5 0.45 96.8 Example 3
Step 5 1.2 96.61 2 0.23 98.61

In Tables 1 to 6, catalyst 1 has a size of 0.1 to 10.0 micrometers, but the catalysts 2 to 3 have a particle size of 0.1 to 3.0 micrometers. The degree of vacuum (-0.5 bar or less) and the drying time (over 48 hours) of each of Examples 1 to 3 were the same, and the number of times was increased to recover the raw material remaining in the particles. As a result, in Example 1-3, the polymerization activity was improved due to the improvement of the purity of the catalyst compared to Comparative Example 2-3, and the effect of increasing the selectivity was confirmed.

As described above, according to the present invention, it was confirmed that when dried at a high degree of temperature (above the melting temperature of glutaric acid) and at a low degree of vacuum, VOC and residual glutaric acid were removed from the catalyst particles. (Vacuum degree -0.5 bar or less) Further, the polymerization selectivity of the catalyst could be improved to 99% by the removal effect of residual glutaric acid. This is higher than previously known results.

Thus, the process can be applied to the preparation of catalysts using zinc salts and dicarboxylic acids, such as zinc glutarate, known in the art.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (7)

Reacting a zinc precursor with a dicarboxylic acid having 3 to 20 carbon atoms in the presence of a solvent to prepare a zinc dicarboxylate-based catalyst, and washing the catalyst, and drying the washed catalyst In the method for producing the zinc-containing catalyst,
The step of drying the catalyst comprises:
a) the washed catalyst is first dried under vacuum at a temperature of from 100 to 140 &lt; 0 &gt; C for 24 to 72 hours,
b) secondary drying the primary dried catalyst at a temperature of from 80 to 140 占 폚 and a pressure of from -1.0 to -0.5 bar for at least 24 hours to 72 hours under high vacuum;
Based catalyst. &Lt; Desc / Clms Page number 24 &gt;
The method according to claim 1,
Further comprising the step of drying and pulverizing the washed catalyst of a) under an inert gas condition prior to the primary drying, or a step of pulverizing the washed catalyst of a) before the primary drying and drying under inert gas conditions A method for producing a zinc-based catalyst.
The method according to claim 1,
Wherein the catalyst comprises a powder having an average particle size of 0.1 to 10.0 micrometers.
The method according to claim 1,
Wherein the secondary drying is carried out two to three times.
The method according to claim 1,
Wherein the zinc precursor is zinc oxide (ZnO), zinc sulfate (ZnSO _4), chlorate, zinc _{(Zn (ClO 3) 2)} , zinc nitrate _{(Zn (NO 3) 2)} , zinc acetate (Zn (OAc) _2), and And zinc hydroxide (Zn (OH) ₂ ).
The method according to claim 1,
Wherein the dicarboxylic acid is at least one compound selected from the group consisting of malonic acid, glutaric acid, succinic acid, adipic acid, terephthalic acid, isophthalic acid, homophthalic acid, and phenylglutaric acid.
A process for producing a polyalkylene carbonate, which comprises polymerizing an epoxide compound and carbon dioxide in the presence of a zinc-based catalyst and a solvent according to any one of claims 1 to 6.

Images