KR101579877B1 - Method for manufacturing end-capped polyalkylene carbonates and fine tuning properties thereof - Google Patents

Abstract

The present invention relates to a process for preparing end-capped polyalkylene carbonate. According to the present invention, there is provided a method for more effectively preparing end-encapsulated polyalkylene carbonate having a urethane bond, whereby a small amount of end-capping agent can easily and precisely change a wider range of properties And it is possible to provide a polyalkylene carbonate having an optimum physical property depending on the application.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for preparing polyalkylene carbonate having a terminal end and a polyalkylene carbonate,

The present invention relates to a process for preparing end-capped polyalkylene carbonate and a method for controlling the properties of a polyalkylene carbonate using the end-capped polyalkylene carbonate.

The polyalkylene carbonate resin is amorphous transparent resin which is biodegradable and pyrolyzable at low temperature unlike aromatic polycarbonate resin, which is a similar engineering plastic, and is completely decomposed into carbon dioxide and water to be free of carbon residue It has advantages.

Generally, polyalkylene carbonates can be synthesized by the reaction of carbon dioxide with an epoxide such as ethylene oxide, propylene oxide, butylene oxide in the presence of an organometallic catalyst.

However, such a polyalkylene carbonate exhibits a pyrolysis mechanism that is separated from the terminal of the polymer in a cascade when exposed to heat. Accordingly, according to previous studies, it has been reported that the polyalkylene carbonate can be reacted with an organic acid such as acetic anhydride, phthalic anhydride, or a diisocyanate to seal the end of the polyalkylene carbonate, thereby improving the thermal stability.

However, the previous end-sealing method for polyalkylene carbonate has a limitation in that the sealing efficiency is lower than the content of the end-sealing agent used in the process. There is a limit in which specific properties such as thermal stability and mechanical properties can be controlled depending on the kind of the compound used in the end-capping of the polyalkylene carbonate. Thus, there is a method in which the properties such as the molecular weight and the melt index of the polyalkylene carbonate can be adjusted as a whole It is a desperate situation.

Accordingly, the present invention aims to provide a method for efficiently producing end-capped polyalkylene carbonate even with a smaller amount of end-capping agent and at the same time more easily and precisely controlling various physical properties of the polyalkylene carbonate .

According to the present invention, a polyalkylene carbonate having a repeating unit represented by the following formula (1) and having a hydroxyl group at both terminals is reacted with a polyvalent isocyanate compound having an average equivalent number of isocyanate groups per molecule of less than 4 and less than 4, And encapsulating at least one end of the recarbonate with a urethane bond-terminating end, wherein the end-capped polyalkylene carbonate comprises at least one urethane bond,

[Chemical Formula 1]

In Formula 1,

R ¹ to R ⁴ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, or a cycloalkyl group having 3 to 20 carbon atoms; At least any two of R ¹ to R ⁴ may be connected to each other to form a cycloalkyl group having 3 to 10 carbon atoms;

and n is an integer of 10 to 1,000.

Here, the content of the isocyanate group in the isocyanate compound may be 20 to 40% by weight based on the total weight of the compound.

And, preferably, the polyisocyanate compound may include a compound represented by the following formula (2): < EMI ID =

(2)

In Formula 2,

m is an integer of 1 to 10;

On the other hand, the polyalkylene carbonate may have a weight average molecular weight of 10,000 to 1,000,000.

The method includes: preparing a solution in which the polyalkylene carbonate is dispersed in an organic solvent; And adding the polyvalent isocyanate compound to the solution and stirring the solution. The polyisocyanate compound may be added in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the polyalkylene carbonate. The stirring may be carried out at a temperature of 15 to 100 DEG C for 30 minutes to 48 hours.

On the other hand, the above production method can be carried out by mixing and stirring the polyalkylene carbonate group and the polyvalent isocyanate compound under non-solvent conditions. The polyisocyanate compound may be added in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the polyalkylene carbonate. The stirring may be carried out at a temperature of 150 to 250 DEG C for 5 to 30 minutes.

According to the present invention, there is provided a method for more effectively preparing end-encapsulated polyalkylene carbonate having a urethane bond, whereby a small amount of end-capping agent can easily and precisely change a wider range of properties And it is possible to provide a polyalkylene carbonate having an optimum physical property depending on the application.

FIG. 1 is a graph showing the results of infrared spectrometry analysis of a polyalkylene carbonate obtained by a method according to an embodiment of the present invention. FIG.

Hereinafter, a process for producing end-capped polyalkylene carbonate according to a specific embodiment of the present invention and a method for controlling the physical properties of a polyalkylene carbonate using the same will be described.

Prior to that, unless expressly stated otherwise, some terms used throughout this specification are defined as follows.

Prior to that, unless explicitly stated throughout the present specification, the terminology is for reference only, and is not intended to limit the invention.

And, the singular forms used herein include plural forms unless the phrases expressly have the opposite meaning.

Also, as used herein, the term " comprises " embodies specific features, regions, integers, steps, operations, elements or components, and does not exclude the presence of other specified features, regions, integers, steps, operations, elements, It does not.

On the other hand, the inventors of the present invention have found that, in the course of repeated studies on polyalkylene carbonate, the present inventors have found that by reacting a polyalkylene carbonate with a polyvalent isocyanate compound having an average equivalent of isocyanate groups per molecule of more than 2 and less than 3, Was encapsulated with a terminal having a urethane bond, it was confirmed that the terminal-encapsulated polyalkylene carbonate could be effectively prepared with only a small amount of the isocyanate compound. Further, according to the above-mentioned method, it has been confirmed that the thermal stability and mechanical properties of the polyalkylene carbonate, as well as the overall physical properties such as molecular weight and melt index, can be more easily controlled, thereby completing the present invention.

According to an embodiment of the present invention,

Reacting a polyalkylene carbonate having a repeating unit represented by the following formula (1) and having a hydroxy group at both terminals with a polyisocyanate compound having an average equivalent number of isocyanate groups per molecule of less than 4 and less than 4, Encapsulating the terminal with a terminal having a urethane bond

A process for preparing a polyalkylene carbonate end-capped comprising:

[Chemical Formula 1]

In Formula 1,

R ¹ to R ⁴ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, or a cycloalkyl group having 3 to 20 carbon atoms; At least any two of R ¹ to R ⁴ may be connected to each other to form a cycloalkyl group having 3 to 10 carbon atoms;

and n is an integer of 10 to 1,000.

According to the present invention, the polyalkylene carbonate may be a polycarbonate-based polymer having a repeating unit represented by the formula (1) and having hydroxyl groups (-OH) at both terminals.

These polyalkylene carbonates can be obtained through copolymerization using epoxide-based compounds and carbon dioxide as monomers in the presence of an organometallic catalyst. The epoxide compound may be at least one compound selected from the group consisting of ethylene oxide, propylene oxide, 1-butene oxide, 2-butene oxide, isobutylene oxide, 1-pentene oxide, 2-pentene oxide, 1-hexene oxide, Pentene oxide, cyclohexene oxide, styrene oxide or butadiene monoxide, and the like, or a combination of two or more different epoxy compounds selected from the foregoing.

Such a polyalkylene carbonate may be a homopolymer containing a repeating unit represented by the above formula (1); Or a copolymer comprising two or more kinds of repeating units belonging to the general formula (1), or a copolymer comprising an alkylene oxide repeating unit and the like together with the repeating unit represented by the general formula (1).

However, the polyalkylene carbonate resin preferably has a repeating unit represented by the general formula (1) so that specific properties (e.g., biodegradability or low glass transition temperature) due to the repeating unit represented by the general formula (1) At least about 40 mole%, preferably at least about 60 mole%, and more preferably at least about 80 mole% of one or more of the monomers.

In the repeating unit represented by the Formula 1, R ¹ to R ⁴ are each independently hydrogen, cycloalkyl having 1 to 20 carbon alkyl group, having 6 to 20 carbon atoms of the aryl group, having 1 to 20 carbon atoms an alkenyl group, or a 3 to 20 carbon atoms in the An alkyl group or the like; At least any two of R ¹ to R ⁴ may be connected to each other to form a cycloalkyl group having 3 to 10 carbon atoms.

At this time, R ¹ to R ⁴ may be selected as appropriate functional groups in consideration of the mechanical properties or biodegradability of the polyalkylene carbonate resin to be finally obtained. For example, when the functional group is hydrogen or a functional group having a relatively small number of carbon atoms, it may be more advantageous in terms of biodegradability, and in the case of a functional group having a relatively large number of carbon atoms, it may be advantageous in terms of mechanical properties such as strength of the resin. As a specific example, it has been reported that polyethylene carbonate is biodegraded more rapidly than polypropylene carbonate (Inoue et al. Chem . Pharm . Bull , Jpn , 1983, 31, 1400; Ree et al. Catalysis Today , 2006, 115, 288-294).

In the polyalkylene carbonate, the degree of polymerization n of the repeating unit represented by the formula (1) may be 10 to 1,000, preferably 50 to 500. The polyalkylene carbonate containing the repeating unit may have a weight average molecular weight of about 10,000 to about 1,000,000, preferably about 50,000 to about 500,000. As the polyalkylene carbonate has the degree of polymerization and the weight average molecular weight, the molded article obtained from the polyalkylene carbonate can exhibit biodegradability along with mechanical properties such as appropriate strength.

On the other hand, according to the present invention, there is provided a method of reacting such a polyalkylene carbonate with a polyvalent isocyanate compound to encapsulate at least one end of the polyalkylene carbonate with a terminal having a urethane bond.

In the present invention, a polyisocyanate compound, particularly a polyisocyanate compound having an average equivalent number of isocyanate groups per molecule of more than 2 and less than 4, is used as a terminal endblock in the terminal endblocking reaction of the polyalkylene carbonate. Accordingly, the present invention can effectively produce end-capped polyalkylene carbonate with a smaller amount of end-capping agent than with the prior mono-isocyanate compound or di-isocyanate compound (MDI, TDI, etc.) have. Further, according to the above-described method, the thermal stability and mechanical properties of the polyalkylene carbonate can be controlled more easily with a smaller amount of the end sealant, as well as the overall physical properties such as the molecular weight and the melt index. Accordingly, the method of producing the terminally encapsulated polyalkylene carbonate according to the present invention can more easily provide the polyalkylene carbonate having the optimum physical properties depending on the application.

Particularly, in order to sufficiently ensure the above effect, the polyisocyanate compound preferably has an average equivalent of isocyanate per molecule of more than 2, more preferably more than 2 and less than 4, even more preferably 2 May be less than 3.

Furthermore, the content of the isocyanate group in the polyisocyanate compound may be 20 to 40% by weight, preferably 25 to 40% by weight, based on the total weight of the compound. That is, it is advantageous that the isocyanate group content of the isocyanate compound is at least 20% by weight based on the total weight of the compound, so that the effect of the aforementioned minimum is exhibited. If the weight of the isocyanate group is higher than necessary, gelation may occur due to excessive reaction between the isocyanate group and the polyalkylene carbonate. Thus, sufficient physical properties may be difficult to obtain and workability may be deteriorated. A side reaction such as self reaction may occur. Therefore, in order to prevent this, it is advantageous that the isocyanate group content in the isocyanate compound is 40 wt% or less based on the total weight of the compound.

Therefore, if the polyisocyanate compound satisfies the above-mentioned conditions, it can be applied to the method of producing the terminal-blocked polyalkylene carbonate according to the present invention without any particular limitation. However, according to the present invention, the polyisocyanate compound may include a compound represented by the following Formula 2:

(2)

In Formula 2,

m is an integer of 1 to 10;

The polyvalent isocyanate compound of formula (2) is a polymer of methylenediphenyl diisocyanate, and can be used in a range that satisfies the above-mentioned conditions. That is, the polyisocyanate compound having the structure of polymeric MDI as shown in Formula 2 and adjusted so that the equivalent of the average isocyanate group per molecule is more than 2, preferably more than 2 and less than 4, more preferably more than 2 but less than 3 Can be used in the production method of the present invention.

Thus, when the above-mentioned polyalkylene carbonate is reacted with a polyvalent isocyanate compound, at least one terminal (preferably both terminals) of the polyalkylene carbonate can be encapsulated with a terminal having a urethane bond. That is, a polyalkylene carbonate end-capped through a mechanism in which a hydroxy group contained in both terminals of the polyalkylene carbonate reacts with an isocyanate group to form a urethane bond can be obtained.

More specifically, the step comprises: preparing a solution in which the polyalkylene carbonate is dispersed in an organic solvent; And adding the polyvalent isocyanate compound to the solution and stirring the solution.

The step of preparing a solution in which the polyalkylene carbonate is dispersed in the organic solvent may be carried out in the presence of a solvent such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, vinyl acetate, methyl ethyl ketone, dichloromethane, dichloroethane, An organic solvent containing an appropriate amount of a polyalkylene carbonate such as methylene chloride, dimethylsulfoxide, nitromethane, nitropropane, caprolactone, acetone, polypropylene oxide, tetrahydrofuran, benzene, styrene, ≪ / RTI >

Then, the polyvalent isocyanate compound is added to the prepared polyalkylene carbonate solution and stirred to induce end-capping reaction of the polyalkylene carbonate.

At this time, the polyisocyanate compound may be added in an amount of 0.1 to 5 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polyalkylene carbonate. That is, in order to induce a change in the physical properties of the polyalkylene carbonate while allowing the minimum end-capping reaction to be induced, the polyvalent isocyanate compound is added in an amount of 0.1 part by weight or more based on 100 parts by weight of the polyalkylene carbonate It is advantageous. When the isocyanate compound is added in an excess amount, the polyalkylene carbonate may change to a property which is not suitable for the application range. In some cases, gelation due to excessive reaction between the isocyanate group and the polyalkylene carbonate occurs And side reactions such as autocrosslinking of isocyanate groups may occur. To prevent this, the polyisocyanate compound is advantageously added in an amount of 5 parts by weight or less based on 100 parts by weight of the polyalkylene carbonate.

And, in order to sufficiently induce the end-capping reaction, the stirring may be carried out at a temperature of 15 to 100 ° C for 30 minutes to 48 hours.

On the other hand, the step of reacting the polyalkylene carbonate with the polyvalent isocyanate compound can be carried out by directly adding the polyvalent isocyanate compound to the polyalkylene carbonate under no solvent condition and using the organic solvent described above and stirring . In this case, the polyisocyanate compound may be added in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the polyalkylene carbonate; The stirring may be carried out at a temperature of 150 to 250 DEG C for 5 to 30 minutes.

As described above, the terminal-blocked polyalkylene carbonate obtained by the method of reacting the polyalkylene carbonate with the polyvalent isocyanate compound is superior to the polyalkylene carbonate having a hydroxy group at both terminals (i.e., not end-capped) Can exhibit a higher glass transition temperature (Tg) and higher molecular weight, can improve mechanical properties such as tensile strength, and can exhibit a lower melt index. Particularly, the present invention uses a polyisocyanate compound having an equivalent isocyanate group average molecular weight per molecule of more than 2 and less than 4 in the terminal endblocking reaction, so that it is possible to more easily and precisely change a wider range of physical properties with only a small amount of an isocyanate compound, It is possible to provide a polyalkylene carbonate having an optimum physical property depending on the intended use.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments are described to facilitate understanding of the present invention. However, the following examples are intended to illustrate the present invention without limiting it thereto.

Example  One

Of about 200 g of polyethylene carbonate (weight-average molecular weight of about 118,000) and the polyvalent isocyanate compound (product name: Lupranate ^® M20S, Manufacturer: a compound represented by the total weight: BASF, the content of the polymeric MDI, equivalent weight of about 2.7, an isocyanate having an average isocyanate group per molecular group (About 0.5% by weight based on 100 parts by weight of polyethylene carbonate) of about 1 g (about 31.5% by weight based on 100% by weight of polyethylene glycol) and stirring at about 190 캜 for about 10 minutes to induce a terminal- .

In order to confirm the result of the end-sealing reaction, the polyethylene carbonate used as the reactant and the final product (end-capped polyethylene carbonate) obtained using the same were analyzed by infrared spectrometry. Respectively. As can be seen from Fig. 1, the polyethylene carbonate of Example 1 was found to be encapsulated with a urethane bond-bearing end.

Example  2

Polyethylene carbonate end-capped was obtained under the same conditions and under the same conditions as in Example 1, except that 1 part by weight of polyisocyanate compound of the same kind was added to 100 parts by weight of polyethylene carbonate.

Example  3

End-capped polyethylene carbonate was obtained under the same conditions and under the same conditions as in Example 1, except that 2 parts by weight of a polyisocyanate compound of the same kind was added to 100 parts by weight of polyethylene carbonate.

Control Example  One

In order to compare the change in physical properties depending on whether or not the terminal was encapsulated, the same unterminated polyethylene carbonate (weight average molecular weight: about 118,000) as that used in Example 1 was prepared as Control Example 1.

Control Example  2

Except that methylenediphenyl diisocyanate (MDI) was used in place of the polyvalent isocyanate compound of Example 1, and 1 part by weight of methylene diphenyl diisocyanate (MDI) was added to 100 parts by weight of polyethylene carbonate, To obtain a terminal-encapsulated polyethylene carbonate under the above-mentioned method and conditions.

Test Example

The glass transition temperature (Tg, 占 폚), the number average molecular weight (Mn, g / gmol), the weight average molecular weight (Mw, g / gmol), the melt each measurement was the index (MI, g / 10min), tensile strength (TS, kg / ㎠) and Td (℃, 50% @ N 2), the results are shown in Table 1 below.

1) Glass transition temperature (Tg, ° C): Measured using differential scanning calorimetry (DSC), and an aluminum pan was used.

2) Number average molecular weight and weight average molecular weight (g / gmol): Measured by gel permeation chromatography (GPC), and polystyrene samples were standardized.

3) Melt index (g / 10 min): The melt index was measured using a fluidity tester at a temperature of 190 캜 under a load of 2.16 kg for 5 minutes.

4) Tensile strength (kg / ㎠): Three to four dumbbell specimens were prepared in accordance with ASTM D 412 and measured at a speed of 50 mm / min using Zwick / Roell Zwick / Z010 model equipment. Respectively.

5) T _d (° C, 50% @ N 2): The temperature was measured at 50% weight reduction of the polymer in a nitrogen atmosphere using a TGA (thermo gravimetric analyzer).

Tg
(° C) Mn
(g / gmol) Mw
(g / gmol) MI
(g / 10 min) TS
(kg / cm2) T _d
(° C) Control Example 1 11.27 37,200 118,000 3.07 41 207 Example 1 12.53 43,416 145,693 2.59 59 261 Example 2 15.4 46,800 152,000 1.78 74 261 Example 3 13.03 58,934 239,309 1.03 80 239 Control Example 2 13.36 40,602 141,745 2.12 60 271

As can be seen from Table 1, when Examples 1 to 3 and Comparative Example 2 were compared with each other on the basis of Control Example 1, the addition amount of the isocyanate compound in Example 2 was the same as in Control Example 2, , It was confirmed that a larger change in most properties such as glass transition temperature, molecular weight, melt index and tensile strength can be induced.

Further, in Examples 1 to 3, it was confirmed that a wider range of properties can be easily and precisely changed depending on the content of the isocyanate compound.

On the other hand, in the case of Control Example 2, the number of hydroxyl groups (-OH, the starting point of pyrolysis mechanism) (maximum of 2) which can remain without participating in the reaction per one polymer chain It is predicted that T _d is higher because it is smaller than the example (branched polymer chain).

Claims (10)

Reacting a polyalkylene carbonate having a repeating unit represented by the following formula (1) and having a hydroxy group at both terminals with a polyisocyanate compound having an average equivalent isocyanate group per molecule of more than 2 and less than 3, Encapsulating the terminal with a terminal having a urethane bond
≪ RTI ID = 0.0 > 1, < / RTI >
[Chemical Formula 1]

In Formula 1,
R ¹ to R ⁴ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, or a cycloalkyl group having 3 to 20 carbon atoms; At least any two of R ¹ to R ⁴ may be connected to each other to form a cycloalkyl group having 3 to 10 carbon atoms;
and n is an integer of 10 to 1,000.
The method according to claim 1,
Wherein the content of the isocyanate group in the isocyanate compound is 20 to 40% by weight of the total weight of the compound.
The method according to claim 1,
Wherein the polyisocyanate compound comprises a compound represented by the following formula (2): < EMI ID =
(2)

In Formula 2,
m is an integer of 1 to 10;
The method according to claim 1,
Wherein the polyalkylene carbonate has a weight average molecular weight of 10,000 to 1,000,000.
The method according to claim 1,
The step may include: preparing a solution in which the polyalkylene carbonate is dispersed in an organic solvent; And adding the polyvalent isocyanate compound to the solution and stirring the resultant mixture.
6. The method of claim 5,
Wherein the polyisocyanate compound is added in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the polyalkylene carbonate.
6. The method of claim 5,
Wherein the stirring is carried out at a temperature of 15 to 100 DEG C for 30 minutes to 48 hours.
The method according to claim 1,
Wherein the polyalkylene carbonate group and the polyvalent isocyanate compound are mixed and stirred under non-solvent conditions.
9. The method of claim 8,
Wherein the polyisocyanate compound is added in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the polyalkylene carbonate.
9. The method of claim 8,
Wherein the stirring is carried out at a temperature of 150 to 250 DEG C for 5 to 30 minutes.

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