KR101183225B1 - Polylactide resin, preparation method thereof and polylactide resin composition comprising the same - Google Patents

Abstract

The present invention relates to a polylactide resin, a method for preparing the same, and a polylactide resin composition including the same, which exhibits improved hydrolysis resistance and heat resistance, together with excellent mechanical properties.

The polylactide resin has an acidity of 10 meq / kg or less and a weight average molecular weight of 100,000 to 1,000,000.

Polylactide resin, acid value, molecular weight, organometallic composite

Description

POLYLACTIDE RESIN, PREPARATION METHOD THEREOF AND POLYLACTIDE RESIN COMPOSITION COMPRISING THE SAME

The present invention relates to a polylactide resin, a method for preparing the same, and a polylactide resin composition including the same, which exhibits improved hydrolysis resistance and heat resistance, together with excellent mechanical properties.

Polylactide (or polylactic acid) resin is a kind of resin containing a repeating unit of the following general formula. Since the polylactide resin is based on biomass, unlike conventional oil-based resins, it is possible to utilize renewable resources and produce less CO ₂ , a global warming gas, than the existing resin. In addition, it is a material that has the appropriate mechanical strength comparable to the existing crude oil-based resins with environmentally friendly properties such as biodegradation by moisture and microorganisms at landfill.

[General Formula]

These polylactide resins have been mainly used for disposable packaging / containers, coatings, foams, films / sheets, and textiles. Recently, polylactide resins have been mixed with existing resins such as ABS, polycarbonate, or polypropylene. After reinforcement, efforts to use semi-permanent uses such as mobile phone exterior materials or automobile interior materials have been actively made. However, polylactide resins are currently limited in their application range due to physical weaknesses of polylactide itself, such as biodegradation by the catalyst used in manufacturing or by factors such as moisture in the air.

On the other hand, as a previously known method for producing a polylactide resin, a method of directly polycondensing lactic acid or a ring opening polymerization of a lactide monomer under an organometallic catalyst is known. Among these methods, direct polycondensation can produce inexpensive polymers, but since it is difficult to obtain a polymer having a high molecular weight of 100,000 or more by weight average molecular weight, it is difficult to sufficiently secure the physical and mechanical properties of the polylactide resin. In addition, the ring-opening polymerization method of the lactide monomer is required to produce the lactide monomer from lactic acid, which requires a higher cost than the polycondensation polymerization. However, a relatively large molecular weight resin can be obtained and the polymerization control is advantageously applied commercially.

As a typical catalyst used for such ring-opening polymerization, Sn containing catalysts, such as Sn (Oct) ₂ (Oct = 2-ethyl hexanoate), are mentioned, for example. However, it has been reported that such catalysts tend not only to accelerate the ring-opening polymerization reaction but also to promote depolymerization under a certain level of conversion (US Pat. No. 5,142,023; Leenslag et al. Makromol. Chem. 1987, 188, 1809-1814; Witzke et al. Macromolecules 1997, 30, 7075-7085). Because of this, the molecular weight of the polylactide resin produced through the ring-opening polymerization is reduced, the molecular weight distribution is widened and the residual monomer content is increased may adversely affect the physical properties.

That is, the lactide ring-opening polymerization reaction initially increases the conversion rate to the polylactide resin according to the polymerization time, but when the conversion rate reaches equilibrium, the monomer-polymer no longer increases even if the polymerization time is extended. It is a reaction involving thermodynamic equilibrium of the liver. This also means that a certain amount of monomer will always be present in the polylactide resin after polymerization. In general, when the reaction temperature is high, the amount of monomer present in the equilibrium state is increased, and when the reaction temperature is lowered, the reverse is known. However, the monomer present in the polylactide resin after polymerization not only adversely affects the mechanical properties of the resin, but also easily hydrates, may cause corrosion during processing, and may promote decomposition by depolymerization of the resin. It is very important to manage the amount.

Due to the above disadvantages, it is difficult to provide a polylactide resin having a sufficiently large molecular weight and excellent mechanical properties due to depolymerization, etc., even in the case of applying the previously known ring-opening polymerization reaction, and furthermore, even during the use of the polylactide resin It is true that the polylactide resin was decomposed by the residual monomer or the catalyst and the hydrolysis resistance or heat resistance was insufficient. Due to these problems, efforts to use polylactide resin for semi-permanent use such as mobile phone exterior materials or automotive interior materials are facing limitations.

On the other hand, attempts have been made to suppress the depolymerization or decomposition of the polylactide resin and to obtain a polylactide resin having higher molecular weight and excellent mechanical properties.

First, a method of adding an amine proton trapping agent during the ring-opening polymerization reaction using the Sn-containing catalyst has been attempted to prevent the depolymerization. However, even with this method, deactivation of the catalyst by acid and hydrolysis of the resin can be prevented to some extent, but depolymerization by the catalyst or the like still proceeds to obtain a polylactide resin having a large molecular weight and excellent mechanical properties. Has been identified (Majerska et al. Macromol Rapid Commun 2000, 21, 1327-1332; Kowalski et al. Macromolecules 2005, 38, 8170-8176).

In addition, a method of using a Zn-containing catalyst instead of Sn has been considered, but in this case, there is a disadvantage of low polymerization activity (Nijenhuis et al. Macromolecules 1992, 25, 6419-6424).

On the other hand, when the lactide is polymerized using Sn (Oct) ₂ (P (Ph) ₃ ) compound, which has recently been coordinated with a phosphine compound, the polymerization activity and molecular weight are increased. It has been reported to be localized and later to induce lactide monomer coordination more rapidly (US Pat. No. 6,166,169; Degee et al Journal Polymer Science Part A; Polymer chemistry 1999, 37, 2413-2420; Degee et al Macromol Symp. 1999, 144, 289-302) In addition, US Pat. No. 5,338,822 discloses a method of preventing depolymerization by adding a phosphite-based antioxidant to a molten resin obtained after lactide polymerization. It has been disclosed.

However, even with such a method, there are limitations in obtaining a polylactide resin exhibiting a large molecular weight and excellent mechanical properties, and it is also difficult to sufficiently prevent depolymerization or decomposition during the use of the resin due to a catalyst or a monomer. Hydrolysis resistance, heat resistance, etc. of resin were also not enough.

Accordingly, the present invention is to provide a polylactide resin exhibiting a higher molecular weight and excellent mechanical properties while suppressing depolymerization or decomposition in use, thereby exhibiting more improved hydrolysis resistance and heat resistance.

In addition, the present invention is to provide a method for producing a polylactide resin that enables the production of the polylactide resin with a high conversion rate.

The present invention also provides a polylactide resin composition including the polylactide resin, which exhibits excellent mechanical properties and heat resistance, and can be used semi-permanently.

The present invention provides a polylactide resin having an acidity of 10 meq / kg or less and a weight average molecular weight of 100,000 to 1,000,000.

The present invention also provides a process for preparing the polylactide resin, which comprises the step of ring-opening polymerization of a lactide monomer in the presence of an organometallic complex of formula (I):

[Formula 1]

Wherein n is an integer from 0 to 15, p is an integer from 0 to 2, a is 0 or 1, M is Sn or Zn, R ¹ and R ³ may be the same or different from each other, and Hydrogen, substituted or unsubstituted C3-C10 alkyl, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted C6-C10 aryl, R ² is substituted or unsubstituted C3 Alkylene of 10 to 10, substituted or unsubstituted cycloalkylene having 3 to 10 carbon atoms, arylene having 6 to 10 carbon atoms substituted or unsubstituted, X and Y are each independently an alkoxy or carboxyl group.

In addition, the present invention provides a process for preparing the polylactide resin, which comprises the step of ring-opening polymerization of the lactide monomer in the presence of the compounds of formulas (2) and (3):

[Formula 2] [Formula 3]

MX_pY_2-p

MX _p Y _2-p

Wherein n is an integer from 0 to 15, p is an integer from 0 to 2, M is Sn or Zn, R ¹ and R ³ may be the same or different from each other, and each hydrogen, substituted or unsubstituted Alkyl having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 10 carbon atoms, substituted or unsubstituted aryl having 6 to 10 carbon atoms, R ² is substituted or unsubstituted alkylene having 3 to 10 carbon atoms, substituted Or unsubstituted cycloalkylene having 3 to 10 carbon atoms, substituted or unsubstituted arylene having 6 to 10 carbon atoms, and X and Y are each independently an alkoxy or carboxyl group.

The present invention also provides a polylactide resin composition comprising the polylactide resin.

Hereinafter, a polylactide resin, a preparation method thereof, and a polylactide resin composition including the same according to specific embodiments of the present invention will be described.

Unless otherwise expressly stated, some terms used throughout this specification are defined as follows.

Unless specifically stated throughout this specification, "comprising" or "containing" means including any component (or component) without particular limitation, and excludes the addition of other components (or components). Cannot be interpreted as.

Further, throughout the present specification, "lactide monomer" can be defined as follows. Lactide can be generally classified into L-lactide composed of L-lactic acid, D-lactide composed of D-lactic acid, and meso-lactide composed of one L-form and one D-form. In addition, the mixture of L-lactide and D-lactide in 50:50 is called D, L-lactide or rac-lactide. Among these lactides, polymerization using only L-lactide or D-lactide with high optical purity is known to yield L- or D-polylactide (PLLA or PDLA) having very high stereoregularity. Lactide is known to have higher crystallization rate and higher crystallization rate than polylactide having low optical purity. However, the term "lactide monomer" in the present specification is defined to include all types of lactide regardless of the difference in properties of lactide according to each form and the difference in properties of polylactide formed therefrom.

And throughout this specification, the term "polylactide resin" is defined as a generic term referring to a homopolymer or copolymer comprising repeating units of the following general formula. Such a "polylactide resin" may be prepared, including the step of forming the following repeating unit by the ring-opening polymerization of the "lactide monomer" described above, and the polymer after the ring-opening polymerization and the formation process of the following repeating unit is completed It may be referred to as "polylactide resin". Here, the term "lactide monomer" includes all types of lactide as described above.

[General Formula]

In the category of polymers which may be referred to as “polylactide resins”, polymers in all states after the ring-opening polymerization and the formation of the repeating unit are completed, for example, in the crude or purified state after the ring-opening polymerization is completed. The polymer of the polymer, the polymer contained in the liquid or solid resin composition before the molding of the product, or the polymer contained in the plastic or fabric, etc., the product molding is completed may be all included. Thus, throughout this specification, the physical properties (acidity, weight average molecular weight or residual catalyst amount, etc.) of the "polylactide resin" are defined as the physical properties of the polymer in any state after the ring-opening polymerization and the formation of the repeating unit are completed. Can be.

Further, throughout the present specification, the term "polylactide resin composition" is defined to include any composition that is contained in or prepared from the above-mentioned "polylactide resin " The category of the composition which may be referred to as such a "polylactide resin composition" may encompass not only liquid or solid resin compositions in a state such as a master batch or pellets before molding a product, but also plastics or fabrics after molding a product. have.

On the other hand, the present inventors have a higher molecular weight and better mechanical properties than any previously known polylactide resin through the production method described below using a specific catalyst, while suppressing decomposition in use, thereby improving hydrolysis resistance and heat resistance It has been found that polylactide resins can be produced, completing the invention.

According to one embodiment of the invention, such polylactide resin may have an acidity of 10 meq / kg or less and a weight average molecular weight of 100,000 to 1,000,000.

Such polylactide resins may have a higher weight average molecular weight than previously known polylactide resins. This high weight average molecular weight is due to the excellent polymerization activity and depolymerization inhibitory action of certain novel catalysts described below, and polylactide resins having a weight average molecular weight of up to 1,000,000 have not been disclosed or provided before. Due to such a high weight average molecular weight, the polylactide resin according to the embodiment of the present invention may exhibit mechanical properties such as tensile strength superior to that of the previously known polylactide resin, and thus may be semipermanent. Enable use.

In addition, the polylactide resin can be provided at a higher molecular weight under a small amount of catalyst due to the excellent activity of the novel catalyst, and can also be obtained in a state in which depolymerization or decomposition is inhibited during or after the polymerization. . Therefore, since the amount of monomers and catalyst remaining in the polylactide resin after polymerization can be minimized, it can exhibit more excellent mechanical properties, and the decomposition during use by the residual monomers can be suppressed to exhibit excellent hydrolysis resistance. have.

In addition, the polylactide resin according to the embodiment of the present invention exhibits low acidity compared to any polylactide resin previously known. Accordingly, during use of the polylactide resin or the product obtained therefrom, it is possible to suppress the degradation of the polylactide resin or the decrease in its molecular weight, thereby further improving the hydrolysis resistance or heat resistance of the polylactide resin. In addition, it has been found that the mechanical and physical properties (eg, tensile strength, etc.) of the polylactide resin can be better maintained.

Non-limiting principles and causes are described as follows.

During the preparation of the polylactide resin, for example, a Sn-containing catalyst for ring-opening polymerization is used, some of which inevitably remains in the final prepared resin. However, such a residual catalyst may be bonded to the terminal of the polylactide resin, and such a binder may cause a transesterification reaction with a carboxylic acid or the like to cause decomposition or reduction in molecular weight of the polylactide resin.

 However, the polylactide resin according to one embodiment of the present invention exhibits low acidity (for example, low carboxylic acid content, etc.), and as the residual catalyst amount decreases as described above, Since decomposition of a polylactide resin and a molecular weight fall can be suppressed, it can exhibit the outstanding decomposition resistance (hydrolysis resistance) or heat resistance. In addition, as the molecular weight decrease of the polylactide resin is suppressed and the occurrence of monomers and the like due to decomposition of the resin is suppressed, the physical and mechanical properties of the polylactide resin can be maintained excellently.

As a result of the experiments of the present inventors, the polylactide resin showing a low acidity of 10 meq / kg or less shows particularly excellent hydrolysis resistance, so that a decrease in molecular weight is hardly observed, and accordingly, physical and mechanical properties such as tensile strength It has been found that physical properties can be maintained very well.

Therefore, the polylactide resin according to the embodiment of the present invention can express and maintain excellent physical and mechanical properties while exhibiting more improved hydrolysis resistance and heat resistance, and thus the polylactide resin for mobile phone exterior materials or automotive interior materials. Permanent use is possible.

On the other hand, the polylactide resin according to an embodiment of the present invention, preferably has an acidity of 3 ~ 10 meq / kg or less and a weight average molecular weight of 200,000 ~ 1,000,000. Accordingly, the polylactide resin can be produced with excellent conversion rate through specific catalysts and production methods described below, while being able to exhibit excellent hydrolysis resistance and heat resistance together with more excellent mechanical properties suitable for semi-permanent use.

In addition, the polylactide resin may have a residual catalyst amount of 15 ppm or less, preferably 10 ppm or less, more preferably 7 ppm or less (eg, 3 to 7 ppm). In addition, as described above, the polylactide resin according to one embodiment of the present invention can be obtained by using a novel catalyst having excellent polymerization activity, and the residual catalyst is such a novel catalyst, that is, Metal complexes or mixtures of compounds of Formulas 2 and 3:

[Formula 1]

[Formula 2] [Formula 3]

MX_pY_2-p

MX _p Y _2-p

Wherein n is an integer from 0 to 15, p is an integer from 0 to 2, a is 0 or 1, M is Sn or Zn, R ¹ and R ³ may be the same or different from each other, and Hydrogen, substituted or unsubstituted C3-C10 alkyl, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted C6-C10 aryl, R ² is substituted or unsubstituted C3 Alkylene of 10 to 10, substituted or unsubstituted cycloalkylene having 3 to 10 carbon atoms, arylene having 6 to 10 carbon atoms substituted or unsubstituted, X and Y are each independently an alkoxy or carboxyl group.

As these new catalysts exhibit excellent polymerization activity, the polylactide resins can be obtained with a large molecular weight under a smaller amount of catalyst, which is why it is 15 ppm or less, preferably 10 ppm or less, more preferably 7 ppm or less. It may have a lower residual catalyst amount. Due to this low amount of residual catalyst, it is possible to prevent the residual catalyst from binding to the ends of the polylactide resin after polymerization or during use to cause backbiting or transesterification reaction, and thus the polylactide resin is decomposed. Disadvantages of reduced molecular weight or reduced molecular weight can be reduced. Therefore, the polylactide resin having a low residual catalyst amount can maintain excellent mechanical properties, and exhibit more excellent hydrolysis resistance and heat resistance.

In addition, as will be described in more detail below, the novel catalyst, in particular, the carbodiimide component corresponding to the formula (2) can act to combine with water or an acid to remove them, thereby the polylactide resin by the water Hydrolysis or transesterification with the acid (e.g., carboxylic acid, etc.) or decomposition or depolymerization of the polylactide resin can be suppressed. Therefore, since the polylactide resin includes such a carbodiimide component in the residual catalyst, decomposition or molecular weight reduction after the polymerization or in use can be further suppressed, thereby providing better mechanical properties, hydrolysis resistance, and the like. Can be represented.

In addition, the polylactide resin according to the embodiment of the present invention may exhibit a weight loss of less than 20 wt% when heated up from room temperature to 300 ° C. according to thermogravimetric analysis (TGA). As supported by the examples described below and FIG. 4 and the like, previously known polylactide resins exhibited a weight loss exceeding 30% by weight when pyrolyzed at temperatures up to 300 ° C. In comparison, the polylactide resin exhibits a weight loss of less than 20 wt%, and may exhibit excellent decomposition resistance and heat resistance. Therefore, the polylactide resin may be suitably used for semi-permanent use.

On the other hand, according to another embodiment of the invention, there is provided a method for producing the polylactide resin described above. According to one embodiment of the invention, the preparation method may include the step of ring-opening polymerization of the lactide monomer in the presence of the organometallic complex of Formula (1). In addition, according to another embodiment of the invention, the preparation method may include the step of ring-opening polymerization of the lactide monomer in the presence of the compound of Formulas 2 and 3.

This production method is ring-opening polymerization of the lactide monomer in the presence of an organometallic complex of formula (1) in which a carbodiimide component is bonded to a metal catalyst, or a mixture of a carbodiimide compound of formula (2) and a metal catalyst of formula (3) Polylactide resin is prepared.

As is also supported by the following examples, these novel catalysts, i.e., the organometallic complexes of formula (1) or mixtures of compounds of formulas (2) and (3) exhibit excellent polymerization activity, so that even when a small amount of catalyst is used, It has been found that polylactide resins of molecular weight can be obtained.

On the other hand, the ring-opening polymerization reaction of the lactide monomer is known that the catalyst is reacted with a hydroxyl group-containing initiator or water to form a metal hydroxy or alkoxide compound, such that the compound is used as a substantially catalytic active species. That is, the ring-opening polymerization reaction is promoted by the metal hydroxy or alkoxide compound to produce a polylactide resin, and some carboxylic acid or hydroxy group-containing compounds remain in the formation of the metal hydroxy or alkoxide compound. Acid or hydroxy group containing compounds are known to be involved in the depolymerization or degradation of polylactide resins (Kowalski et al. Macromolecules 2000, 33, 7359-7370).

More specifically, the depolymerization or decomposition resulting from the polymerization and equilibrium reaction of the polylactide resin is mainly carried out by the hydrolysis reaction by water and lactic acid contained in the carboxylic acid or lactide monomer, by a catalyst bonded to the terminal of the polymer chain. It is predicted that a back-biting reaction or a catalyst occurs due to a transesterification reaction between a polymer chain attached to the terminal and a carboxylic acid and the like.

However, it is expected that certain carbodiimide components included in the novel catalysts of Formula 1 or Formulas 2 and 3 may be combined with water or carboxylic acids to remove them. Therefore, when the ring-opening polymerization of the lactide monomer is carried out using such a novel catalyst, hydrolysis reaction or transesterification reaction by the moisture or carboxylic acid or the like can be suppressed, and thus depolymerization of the polylactide resin or Decomposition and the like can be greatly reduced.

Therefore, according to the production method of another embodiment of the invention using the novel catalyst, due to the excellent polymerization activity of the catalyst and the inhibitory action such as depolymerization, a polylactide resin having a large molecular weight can be produced with excellent conversion rate.

In addition, as the new catalyst acts to remove water or acid, according to the above production method, a polylactide resin having a lower acidity can be produced, thereby degrading the polylactide resin after polymerization or in use. Etc. can also be greatly suppressed.

In addition, since the novel catalyst enables the production of polylactide resins having a large molecular weight even with a relatively small amount of use due to the excellent polymerization activity, a resin having a lower residual catalyst amount can be produced by the above production method. .

Therefore, by the production method according to another embodiment of the present invention, a polylactide resin suitable for semi-permanent use, that is, a polylactide resin having a large weight average molecular weight, a low acid value, and the like can be produced at a high conversion rate.

On the other hand, in the production method according to another embodiment of the invention, the lactide monomer may be prepared from lactic acid. In addition, the lactide monomer may be any form of lactide, including all forms of lactide, for example, L, L-lactide, D, L-lactide or D, D-lactide and the like.

And, in the above production method, the compound of Formula 1 or Formula 2 is a specific carbodiimide substituted with an alkyl group, a cycloalkyl group, an alkylene group or a cycloalkylene group having 3 to 10 carbon atoms or an aryl group or arylene group having 6 to 10 carbon atoms It may have a structure, as is also supported by the examples and comparative examples described below, as the compound has such a specific carbodiimide structure exhibits excellent polymerization activity, while effectively removing the water or acid contained in the resin, etc. The polylactide resin having the large molecular weight and low acidity described above can be produced. More specifically, as the compound of Formula 1 or Formula 2, R ¹ is a monovalent phenyl group substituted with an alkyl group of 1 to 10 carbon atoms, an alkyl group of 3 to 10 carbon atoms, or a cycloalkyl group, and R ² is of 1 to 10 carbon atoms. A compound that is a divalent phenylene group substituted with an alkyl group, an alkylene group having 3 to 10 carbon atoms, or a cycloalkylene group can be used.

In addition, MX _p Y _2-p or the compound of formula 3 bonded to the formula (1) may be a Sn or Zn-containing compound or a mixture of two or more thereof, representative examples of such compounds are tin (II) 2-ethylhexanoate (Sn (Oct) ₂ ) is mentioned.

In addition, the organometallic complex of Chemical Formula 1 may be prepared by a method including the step of reacting the compounds of Chemical Formulas 2 and 3, as supported by the following examples.

In addition, in the production method according to another embodiment of the present invention, the organometallic complex of Formula 1 or the compound of Formula 2 and 3 are each added in a ratio of 0.001 to 0.1 mole to 100 moles of lactide monomer to the ring opening The polymerization may proceed. If the addition ratio of such a catalyst is too small, the polymerization activity is not sufficient, and if the addition ratio of the catalyst is too large, the residual catalyst amount of the polylactide resin produced may increase, resulting in decomposition of the resin or reduction of molecular weight. have.

In addition, according to the method for preparing the polylactide resin, the organometallic complex of Formula 1 may be used as a single catalyst, or a mixture of the compounds of Formulas 2 and 3 may be used as a catalyst, and the high molecular weight of the resin obtained through polymerization In view of polymerization activity or conversion to resin, it is more preferable to use the organometallic complex represented by Chemical Formula 1 as a single catalyst.

In addition, when using the compounds of Formulas 2 and 3 as a catalyst, these compounds may be added at the same time, but may be added sequentially with a time difference, or added at regular intervals before the addition of monomers and the start of polymerization or just before the start of polymerization. Of course, it may be added to. However, in order to allow the compounds of the formulas (2) and (3) to react to some extent to form their complexes, the compounds of the formulas (2) and (3) are simultaneously added at regular intervals before the start of polymerization, and then the monomers are added to the polymerization. It is preferable to disclose.

In addition, in the method for producing the polylactide resin, the ring-opening polymerization reaction may proceed in the presence of an initiator containing a hydroxy group-containing compound. Such initiators may serve to react with the catalyst to form substantially catalytically active species and to initiate the ring-opening polymerization reaction. In addition, the initiator may play a role in controlling the molecular weight by participating in some depolymerization or decomposition of the resin.

As such an initiator, a compound having a hydroxy group can be used without particular limitation. However, when such a compound has a carbon number of less than 8, the molecular weight may be low, so that it may be vaporized at the ring-opening polymerization temperature, which may make it difficult to participate in the polymerization reaction. Therefore, it is preferable to use a hydroxy group containing compound having 8 or more carbon atoms as the initiator.

In addition, such an initiator may be added at a ratio of 0.001 to 1 mol based on 100 mol of the lactide monomer to proceed the ring-opening polymerization. If the addition ratio of such an initiator is too small, the molecular weight of the resin obtained by ring-opening polymerization may be too high, and subsequent processing may be difficult. If the addition ratio of the initiator is too large, the molecular weight and polymerization activity of the resin may be lowered.

In addition, the ring-opening polymerization reaction of the lactide monomer is preferably proceeded to bulk polymerization using substantially no solvent. In this case, substantially no solvent may be encompassed until a small amount of solvent for dissolving the catalyst, for example, up to 1 ml of solvent per 1 kg of lactide monomer used is used.

As the ring-opening polymerization proceeds to bulk polymerization, the step for removing the solvent after the polymerization can be omitted, and decomposition or loss of the resin in the solvent removing step can also be suppressed. In addition, the polylactide resin can be obtained in high conversion and yield by the bulk polymerization.

In addition, the ring-opening polymerization of the lactide monomer may be performed at a temperature of 120 to 200 ° C. for 0.5 to 8 hours, preferably for 0.5 to 4 hours. In the above-described manufacturing method, by using a catalyst having excellent activity, even if the ring-opening polymerization is carried out for a shorter time than previously known, a polylactide resin having a large molecular weight can be obtained with high conversion and yield, and a short time progresses polymerization. This is preferable because depolymerization or decomposition of the resin can also be reduced.

According to the above-described manufacturing method, a polylactide resin, for example, a polylactide resin according to an embodiment of the present invention having high molecular weight, low acidity, and the like and exhibiting excellent mechanical properties, hydrolysis resistance, and heat resistance It is possible to produce at a high conversion rate.

On the other hand, according to another embodiment of the invention is provided a polylactide resin composition comprising the polylactide resin described above.

Since the polylactide resin composition includes a polylactide resin exhibiting excellent mechanical properties, hydrolysis resistance, and heat resistance, the polylactide resin composition exhibits excellent physical and mechanical properties, and thus may be preferably used for semi-permanent use in electronics packaging or automotive interior materials. have.

The polylactide resin composition may include polylactide resin alone or may include polycarbonate resin, ABS resin, or polypropylene resin. However, the resin composition is 40% by weight or more, preferably 60% by weight or more, and more preferably 80% by weight or more, based on the content of the total resin contained therein, so that the polylactide resin may exhibit unique physical properties. And lactide resins.

In addition, the polylactide resin composition may further include various additives previously included in various resin compositions.

The polylactide resin composition may be a liquid or solid resin composition before molding the final product, or may be a plastic or a fabric in the final product state. The final plastic or fabric product or the like may be prepared by a conventional method ≪ / RTI >

As described above, according to the present invention, a polylactide resin and a method for preparing the same may be provided that exhibit excellent mechanical properties and exhibit improved decomposition resistance and heat resistance.

Accordingly, the present invention requires a semi-permanent use of a polylactide resin, which is limited to a conventional disposable material, as well as disposable products such as food packaging films, household goods films and sheets, as well as electronic product packaging or automotive interior materials. It can greatly contribute to making it applicable to various fields of materials.

Hereinafter, the operation and effects of the invention will be described in more detail with reference to specific examples of the invention. However, these embodiments are only presented as an example of the invention, whereby the scope of the invention is not determined.

Experimental Method

In the examples and comparative examples below, all operations dealing with air or water sensitive compounds were carried out using standard Schlenk techniques or dry box techniques.

Nuclear magnetic resonance spectra were obtained using a Bruker 600 spectrometer, and ¹ H NMR was measured at 600 MHz.

The molecular weight and molecular weight distribution of the polymer were measured using gel permeation chromatography (GPC), wherein a polystyrene sample was used as a standard.

Synthesis Example 1

Sn (Oct) ₂ (Aldrich) (0.2 g, 0.49 mmol) and a compound of formula (4) (TCI) (0.36 g, 1.0 mmol) were respectively added to a 100 mL flask, and 30 mL of toluene was added to 1 at 100 ° C. Stir for hours. Thereafter, the solvent was removed in vacuo, washed with heptane solvent, and dried to obtain 0.36 g of organometallic complex A.

[Formula 4]

[Synthesis Example 2]

Sn (Oct) ₂ (Aldrich) (0.2 g, 0.49 mmol) and 0.36 g of the compound represented by the following formula (Rinchemisa) were each charged in a 100 mL flask, and 0.4 g of the organic metal complex B was obtained in the same manner as in Synthesis example 1. .

1 is a ¹³ C NMR spectrum for organometallic complex B. FIG. Referring to FIG. 1, three carbonyl peaks (188, 183, 182ppm) in the reaction between the Sn (Oct) ₂ catalyst and the compound of Formula 5 are shown to be very sharp in case of 183, thus binding to the compound of Formula 5 Peaks at 188 ppm are consistent with free Sn (Oct) _2, and broad peaks at 182 ppm are found in the organometallic complexes Seems to be about.

[Chemical Formula 5]

[Synthesis Example 3]

Sn (Oct) ₂ (Aldrich) (0.2 g, 0.49 mmol) and a compound of formula (6) (TCI) (0.12 g, 1.0 mmol) were respectively added to a 100 mL flask, and 30 mL of toluene was added to 1 at 100 ° C. Stir for hours. Then, the solvent was removed under vacuum, washed with heptane solvent and dried to obtain 2.5 g of organometallic complex C.

[Formula 6]

[Synthesis Example 4]

Sn (Oct) ₂ (Aldrich) (0.2 g, 0.49 mmol) and a compound of formula (TCI) (0.21 g, 1.0 mmol) were added to a 100 mL flask, respectively, and 30 mL of toluene was added to 1 at 100 ° C. Stir for hours. Then, the solvent was removed under vacuum, washed with heptane solvent and dried to obtain 2.9 g of organometallic complex D.

[Formula 7]

Example 1

Preparation of Polylactide Resin Using Organometallic Composite A (Lactide / Sn = 1/20000 (mol / mol), 140 ° C)

Lactide monomer (2 g, 13.8 mmol) and organometallic complex A (0.2 mL, 3.5 mM toluene solution) of Synthesis Example 1 were respectively added to 30 mL vials, and left to stand for 12 hours under vacuum. The reaction was carried out for a time. After the solid polymer was dissolved in 30mL of chloroform and precipitated under methanol solvent. The precipitate was filtered through a glass funnel, and the recovered polymer was dried in a vacuum oven at 50 ° C. for 24 hours to obtain 1.88 g of polylactide resin (81 wt% based on the total amount of monomer introduced). The molecular weight (Mw) was 727,000 and Mw / Mn was 2.0.

[Example 2]

Preparation of Polylactide Resin Using Organometallic Composite A (Lactide / Sn = 1/20000 (mol / mol), 160 ° C)

Lactide monomer (2 g, 13.8 mmol) and organometallic complex A (0.2 mL, 3.5 mM toluene solution) of Synthesis Example 1 were each added to a 30 mL vial, and left for 12 hours under vacuum, followed by 1 at 160 ° C polymerization temperature. The reaction was carried out for a time. In the same manner as in Example 1, 1.84 g of a polylactide resin (92 wt% based on the total amount of monomers introduced) was obtained. The molecular weight (Mw) was 491,000 and Mw / Mn was 2.0.

[Example 3]

Preparation of Polylactide Resin Using Organometallic Composite A (Lactide / Sn = 1/60000 (mol / mol), 180 ° C)

Lactide monomer (2 g, 13.8 mmol) and organometallic complex A (0.07 mL, 3.5 mM toluene solution) of Synthesis Example 1 were each added to 30 mL vials, which were left under vacuum for 12 hours and 1 hour at 180 ° C polymerization temperature. Reacted for a while. In the same manner as in Example 1, 1.34 g of a polylactide resin (81 wt% based on the total amount of added monomers) was obtained. The molecular weight (Mw) was 274,000, and Mw / Mn was 1.7.

Example 4

Preparation of Polylactide Resin Using Organometallic Composite B (Lactide / Sn = 1/20000 (mol / mol), 140 ° C)

Lactide monomer (2 g, 13.8 mmol) and organometallic complex B (0.2 mL, 3.5 mM toluene solution) of Synthesis Example 2 were each added to 30 mL vials, which were left under vacuum for 12 hours and 1 hour at 140 DEG C polymerization temperature. Reacted for a while. After the solid polymer was dissolved in 30mL of chloroform and precipitated under methanol solvent. The precipitate was filtered through a glass funnel, and the recovered polymer was dried in a vacuum oven at 50 ° C. for 24 hours to obtain 1.67 g of polylactide resin (81 wt% based on the total amount of monomer introduced). The molecular weight (Mw) was 711,000 and Mw / Mn was 1.7.

[Example 5]

Preparation of Polylactide Resin Using Organometallic Composite B (Lactide / Sn = 1/20000 (mol / mol), 160 ° C)

Lactide monomer (2 g, 13.8 mmol) and organometallic complex B (0.2 mL, 3.5 mM toluene solution) of Synthesis Example 2 were each added to 30 mL vials, which were left under vacuum for 12 hours and 1 hour at 160 ° C polymerization temperature. Reacted for a while. In the same manner as in Example 1, 1.72 g of a polylactide resin (81 wt% based on the total amount of added monomers) was obtained. The molecular weight (Mw) was 684,000, and Mw / Mn was 1.8.

 [Example 6]

Preparation of Polylactide Resin Using Organometallic Composite B (Lactide / Sn = 1/60000 (mol / mol), 180 ° C)

Lactide monomer (2 g, 13.8 mmol) and organometallic complex B (0.07 mL, 3.5 mM toluene solution) of Synthesis Example 2 were each added to 30 mL vials, which were left under vacuum for 12 hours and 1 hour at 180 ° C polymerization temperature. Reacted for a while. In the same manner as in Example 1, 1.61 g of a polylactide resin (81 wt% based on the total amount of added monomers) was obtained. The molecular weight (Mw) was 276,000, and Mw / Mn was 1.9.

[Example 7]

Preparation of Polylactide Resin Using Organometallic Composite B (Lactide / Sn = 1/80000 (mol / mol), 180 ° C)

Lactide monomer (2 g, 13.8 mmol) and organometallic complex B (0.05 mL, 3.5 mM toluene solution) of Synthesis Example 2 were each added to 30 mL vials, and left for 12 hours under vacuum, followed by 4 hours at 180 ° C polymerization temperature. Reacted for a while. In the same manner as in Example 1, 1.8 g of a polylactide resin (88 wt% based on the total amount of added monomers) was obtained. The molecular weight (Mw) was 221,000 and Mw / Mn was 1.8.

[Example 8]

Preparation of Polylactide Resin Using Organometallic Composite C (Lactide / Sn = 1/40000 (mol / mol), 180 ° C)

Lactide monomer (2 g, 13.8 mmol) and organometallic complex C (0.1 mL, 3.5 mM toluene solution) of Synthesis Example 3 were each added to 30 mL vials, which were left under vacuum for 12 hours and 1 hour at 180 ° C polymerization temperature. Reacted for a while. In the same manner as in Example 1, 1.67 g of a polylactide resin (83 wt% based on the total amount of added monomers) was obtained. The molecular weight (Mw) was 214,000, and Mw / Mn was 1.7.

[Example 9]

Preparation of Polylactide Resin Using Organometallic Composite D (Lactide / Sn = 1/40000 (mol / mol), 180 ° C)

Lactide monomer (2 g, 13.8 mmol) and organometallic complex D (0.1 mL, 3.5 mM toluene solution) of Synthesis Example 4 were each added to 30 mL vials, which were left under vacuum for 12 hours and 1 hour at 180 ° C polymerization temperature. Reacted for a while. In the same manner as in Example 1, 1.78 g of a polylactide resin (89 wt% based on the total amount of monomers introduced) was obtained. The molecular weight (Mw) was 257,000 and Mw / Mn was 1.9.

[Example 10]

Preparation of Polylactide Resin in the Presence of Compound of Formula 5 and Sn (Oct) ₂ Catalyst (Lactide / Sn = 1/60000 (mol / mol) , 180 ° C.)

Lactide monomer (2 g, 13.8 mmol), the compound of formula 5 (Rheinchem Co., Ltd.) (0.1 wt% by weight of lactide), Sn (Oct) ₂ (0.07 mL, 3.5 mM toluene solution) were added to 30 mL vials, respectively. The mixture was left under vacuum for 12 hours and reacted at 180 ° C. for 2 hours. In the same manner as in Example 1, 1.61 g of a polylactide resin (81 wt% based on the total amount of added monomers) was obtained. The molecular weight (Mw) was 337,000 and Mw / Mn was 1.93.

[Example 11]

Preparation of Polylactide Resin in the Presence of Compound of Formula 5 and Sn (Oct) ₂ Catalyst (Lactide / Sn = 1/80000 (mol / mol) , 180 ^° C.)

Lactide monomer (2 g, 13.8 mmol), the compound of formula 5 (Rheinchem Co., Ltd.) (0.1 wt% by weight of lactide), Sn (Oct) ₂ (0.05 mL, 3.5 mM toluene solution) were added to 30 mL vials, respectively. The mixture was left under vacuum for 12 hours and reacted at 180 ° C. for 1 hour. In the same manner as in Example 1, 1.56 g of a polylactide resin (78 wt% based on the total amount of added monomers) was obtained. The molecular weight (Mw) was 231,000 and Mw / Mn was 1.84.

[Example 12]

Molecular weight control by initiator in preparing polylactide resin by organometallic complex B

Lactide monomer (2 g, 13.8 mmol) and organometallic complex B (0.2 mL, 3.5 mM toluene solution) were added to 30 mL vials, and 2-ethyl hexyl lactate, dodecyl alcohol, and octanol were added to each vial. A hydroxyl group-containing initiator such as ethylhexyl alcohol was added at a ratio of 1/1000, 2/1000, and 4/1000 (mol / mol) to the lactide monomer, and then reacted at 180 ° C. for 2 hours. Thereafter, the reaction was carried out in the same manner as in Example 1. Table 1 is a table showing the amount of initiator added, the conversion to polylactide resin, and the weight average molecular weight.

Alcohol (mol / mol) 1/1000 2/1000 4/1000 Conversion rate
(%) Ethylhexyl lactate 84.1 90.9 89.9 Dodecyl alcohol 89.1 88.2 87.9 Ethylhexyl alcohol 86.1 85.6 83.6 Octanol 90.3 90.8 89.2 Molecular Weight
(Mw * 10 ^-3 Da) Ethylhexyl lactate 318 286 147 Dodecyl alcohol 375 268 176 Ethylhexyl alcohol 415 398 185 Octanol 356 295 148

Referring to Examples 1 to 12, when preparing a polylactide resin using an organometallic complex of Formula 1 or a mixture of compounds of Formulas 2 and 3 as a catalyst, a large weight average molecular weight of at least 100,000 in a relatively short time It was confirmed that the polylactide resin having a high yield can be obtained.

In addition, referring to Table 1 of Example 12, a polylactide resin can be obtained with a higher conversion rate when the hydroxy group-containing initiator is added, and the polylock increases as the amount of the initiator is increased or the hydroxy group-containing initiator has a long chain. It was confirmed that the molecular weight of the tide resin can be reduced to function as a molecular weight control.

[Experimental Example 1]

Measurement of catalyst residue in polylactide resin

The catalyst residue in the polylactide resin was measured by inductively coupled plasma emission spectroscopy. In this manner, the residual catalyst amounts of the polylactide resins prepared in Examples 7, 9, and 10 were measured and shown in Table 2 below.

Catalyst Residue (ppm) Example 7 5 Example 9 15 Example 10 5

Referring to Table 2, it was confirmed that the polylactide resin prepared in Example had a low residual catalyst amount of about 5 to 15 ppm.

From this, it is expected that the polylactide resin according to the above embodiment will have a great reduction in depolymerization or decomposition by residual catalyst after polymerization or in use, thereby having excellent hydrolysis resistance or heat resistance.

[Experimental Example 2]

Preparation of Polylactide Resin

The lactide monomers (2 g, 13.8 mmol) and Sn (Oct) ₂ (Aldrich) in the same manner as in Example 1, except that Sn (Oct) ₂ (Aldrich) was used as the catalyst instead of the organometallic complex A. 0.28 mg, Sn / Mon = 1/20000 (mol / mol)) were added to 30 mL vials, respectively, and the reaction proceeded while changing the polymerization time at 140 and 160 ° C. polymerization temperatures (Comparative Example 1 and Comparative Example 2, respectively). ), The polymerization yield of the polylactide resin (conversion to polylactide resin) and the weight average molecular weight were measured. The measurement result is shown in Table 3 compared with the measurement result of the polylactide resin obtained by carrying out reaction by the same method (same polymerization temperature and Sn molar ratio in a catalyst) about Example 4 and Example 5, Conversion and molecular weight graphs are shown in FIGS. 2 and 3.

Comparative Example 1 Comparative Example 2 Example 4 Example 5 Polymerization temperature (℃) 140 160 140 160 Sn / Mon (mol / mol) 1/20000 1/20000 1/20000 1/20000 Time (h) % Conversion 0.5 19.4 64.6 77.2 One 20.0 20.0 83.5 85.6 2 26.3 91.4 91.4 4 34.6 37.3 88.2 90.8 Mw (* 10 ^-3 Da) 0.5 71.9 470.0 626.0 One 70.9 49.0 711.0 684.0 2 61.0 821.0 670.0 4 139.0 124.9 892.0 614.0 Mw / Mn 0.5 1.3 1.5 1.8 One 1.2 1.5 1.7 1.8 2 1.3 2.0 2.0 4 1.5 1.4 1.9 1.9

Referring to Table 3, Figures 2 and 3, in the case of preparing a polylactide resin using an organometallic complex of formula (1) or a mixture of compounds of formulas (2) and (3) as a catalyst, polylactide from the beginning of the polymerization The conversion rate to the resin increased to 80% or more, and gradually increased thereafter, and the molecular weight of the polylactide resin also increased to about 40 to 600,000 in the first 0.5 hours, and then gradually increased or maintained almost after the maximum molecular weight. It was confirmed that.

In contrast, when using a conventional Sn (Oct) ₂ catalyst according to the comparative example, the conversion to polylactide resin is very low at 50% or less, and the molecular weight of the polylactide resin is also at most 150,000 or less. This was confirmed.

From this, it was confirmed that according to the production method of the example, a polylactide resin having a large molecular weight of 400,000 or more can be obtained in a short time with a high conversion rate.

[Comparative Example 3]

Except using Bis (trimethylsilyl) carbodiimide, phosphite or phenolic additives (0.1% by weight relative to lactide monomers), except that Sn (Oct) ₂ (Aldrich) was used as catalyst instead of organometallic complex A. In the same manner as in Example 1, lactide monomer (2 g, 13.8 mmol) and Sn (Oct) 2 (0.14 mg, Sn / Mon = 1/40000 (mol / mol)) were added to 30 mL vials, respectively, followed by polymerization at 180 ° C. After the reaction was carried out while changing the polymerization time at the temperature, the polymerization yield (conversion) and the weight average molecular weight were measured. A carbodiimide compound containing silicon atoms, that is, bis (trimethylsilyl) carbodiimide, was used, TNPP and Irgafos 126 were used as phosphite additives, and Irganox 1076 was used as phenolic additives. The conversion and the weight average molecular weight data obtained as a result of such polymerization are shown in Table 4.

additive Polymerization time (hr) % Conversion Mw (* 10 ^-3 Da) Mn (* 10 ^-3 Da) PDI Bis (trimethylsilyl) carbodiimide One 17.5 23.1 19.3 1.2 2 25.6 35.2 25.1 1.4 4 48.9 5.86 41.8 1.4 TNPP One 23.6 51.7 38.8 1.3 2 24.5 33.7 27.0 1.2 4 45.7 86.7 57.9 1.5 IRF 126 One 14.6 19.0 17.9 1.1 2 32.4 57.6 47.0 1.2 4 50.1 49.8 34.5 1.4 IRN 1076
One 25.6 43.5 35.6 1.2 2 41.6 52.2 40.2 1.3 4 57.7 75.1 49.3 1.5

Referring to Table 4 above, without using a specific carbodiimide compound substituted with an alkyl group, a cycloalkyl group or an aryl group (eg, a compound of Formula 2 or an organometallic complex of Formula 1 to which such a compound is bonded), In the case of using a bodyimide compound, it was confirmed that not only the conversion to polylactide resin was low due to low polymerization activity, but also a polylactide resin having a low weight average molecular weight was obtained. In addition, as disclosed in U.S. Patent No. 5,338,822 or the like, even when using an phosphite or phenolic additive, a polylactide resin having a weight average molecular weight of about 90,000 or less is obtained, and thus a polylactide resin having a large molecular weight It has been found that there is a limit to obtaining.

[Experimental Example 3]

Acidity was measured about the polylactide resin obtained by superposing | polymerizing in Comparative Examples 1 and 2 for 4 hours, and the polylactide resin obtained in Examples 3 and 7. The acidity was measured using a Metrohm 809 Titando instrument, and 0.1 N KOH ethanol solution was used as the titration solution. The results are shown in Table 5.

Referring to Table 5, the polylactide resin of Example showed a low acidity of 5 meq / kg or less, whereas the comparative example showed a high acidity of 35 meq / kg or more. It was confirmed from this that the polylactide resin having a large molecular weight and a low acidity can be obtained from the production method of the example. In addition, as the polylactide resin of this embodiment has a low acidity, the transesterification reaction or hydrolysis reaction of the resin to which the catalyst is bonded to the terminal and the water or the acid is suppressed, so that the decomposition of the polylactide resin after polymerization or It is expected that molecular weight reduction and the like can be greatly reduced. Accordingly, it is expected that the polylactide resin of the above example may maintain excellent mechanical properties due to high molecular weight, but may exhibit more improved decomposability and the like.

PH (meq / Kg) Example 3 3 Example 7 4 Comparative Example 1 35 Comparative Example 2 41

[Experimental Example 4]

TGA analysis was performed to test the thermal stability of the polylactide resin obtained by polymerization in Comparative Example 1 for 2 and 4 hours and the polylactide resin obtained in Examples 6 and 11, respectively. The results are shown in FIG. In FIG. 4, Comparative Example 1-2 shows an analysis result for the polylactide resin obtained by polymerization for 2 hours in Comparative Example 1, and Comparative Example 1-4 shows the analysis result for the polylactide resin obtained by polymerization for 4 hours. Indicates. In addition, the TGA analysis was carried out while increasing the temperature at a temperature increase rate of 10 ℃ / min from room temperature to 400 ℃, mettler-toledo TGA 851e was used as the TGA analyzer.

Referring to FIG. 4, the polylactide resin of the Example exhibits a weight reduction of less than 20% by weight due to minimization of decomposition even when the temperature is raised to about 300 ° C., whereas the polylactide resin of the comparative example is heated to about 300 ° C. It has been found to exhibit a weight loss of at least 30% by weight.

Therefore, it was confirmed that the polylactide resin of the example exhibits excellent decomposition resistance and heat resistance compared to the polylactide resin of the comparative example, and that a large molecular weight and thus excellent mechanical properties can be maintained.

Experimental Example 6 Hydrolysis Analysis

The lactide monomers (2 g, 13.8 mmol) and Sn (Oct) ₂ (Aldrich) in the same manner as in Comparative Example 1 except that the amount of Sn (Oct) ₂ (Aldrich) catalyst and the polymerization temperature were different. (0.14 mg, Sn / Mon = 1/40000 (mol / mol)) were added to 30 mL vials, respectively, and the reaction was performed while changing the polymerization time at 180 ° C. polymerization temperature, thereby obtaining Comparative Example 4 (weight average molecular weight 200,000; A polylactide resin having an acidity of 20 meq / kg) and Comparative Example 5 (weight average molecular weight 235,000; acidity of 15 meq / kg) were obtained. With the polylactide resins of Comparative Examples 4 and 5, polylactide resins of Examples 8 (weight average molecular weight 214,000; acidity 8 meq / kg) and Example 11 (weight average molecular weight 231,000; acidity 4 meq / kg) The specimen was prepared by applying an injection molder of HAAKE Minijet II.

The specimens were maintained under a constant temperature and humidity condition of 60 ° C. and 90%, and the degree of retention of hydrolysis resistance and mechanical properties was evaluated by measuring changes in tensile strength, molecular weight and acidity over time. These evaluation results are summarized in Table 6 below.

Comparative Example 4 Comparative Example 5 Example 8 Example 11 Time (hr) 0 10 24 0 10 24 0 10 24 0 10 24 PH (meq / kg) 20 36 55 15 22 48 8 8 10 4 4 5 Molecular Weight
(* E-3, g / mol) 200 180 125 235 198 139 214 203 195 231 220 206 The tensile strength
(Kg? Fcm / cm) 610 550 220 625 555 230 610 598 550 620 612 590

Referring to Table 6, the polylactide resin of the example having a low initial acidity of 10 meq / kg or less hardly observed a decrease in the mechanical properties such as molecular weight decrease or tensile strength over time even under the harsh conditions of high temperature and high humidity. Was confirmed.

In comparison, the polylactide resin of the comparative example having an acidity of more than 10 meq / kg has a large decrease in molecular weight (weight average molecular weight decrease of 70,000 or more) and tensile strength over time, even if it initially shows high molecular weight and excellent mechanical properties. It was confirmed that there was a marked drop in strength (approximately one third).

This is because the polylactide resin of Examples exhibits a low acidity, so that the transesterification reaction or hydrolysis reaction of the resin with the residual catalyst bound to the terminal and water or acid is suppressed, so that the decomposition or molecular weight of the polylactide resin after polymerization is suppressed. It seems to be because there is almost no decrease.

From the above experimental results, the polylactide resin of the embodiment having a low acidity of 10 meq / kg or less and a high molecular weight not only exhibits excellent mechanical properties according to a large molecular weight, but also shows excellent hydrolysis resistance due to low acidity. It was confirmed that it is possible to maintain the semi-permanent use of polylactide resin.

1 is a ¹³ C NMR spectrum of the organometallic composite of Synthesis Example 2. FIG.

Figure 2 is a graph showing the change in conversion rate to polylactide resin according to the ring-opening polymerization progress time in Examples 4 and 5 and Comparative Examples 1 and 2.

3 is a graph showing the weight average molecular weight change of the polylactide resin according to the ring-opening polymerization progress time in Examples 4 and 5 and Comparative Examples 1 and 2.

Figure 4 is a graph showing the thermogravimetric analysis (TGA) results for the polylactide resin prepared in Examples 6 and 9 and Comparative Example 1.

Claims (16)

A polylactide resin having an acidity of 10 meq / kg or less and a weight average molecular weight of 100,000 to 1,000,000, and comprising a residual catalyst containing an organometallic complex of Formula 1 or a compound of Formulas 2 and 3: [Formula 1]

[Formula 2] [Formula 3]

MX _p Y _2-p Wherein n 'is an integer from 1 to 15, n is an integer from 0 to 15, p is an integer from 0 to 2, a is 0 or 1, M is Sn or Zn, R ¹ and R ³ May be the same as or different from each other, and are each hydrogen, alkyl having 3 to 10 carbon atoms, cycloalkyl having 3 to 10 carbon atoms, aryl having 6 to 10 carbon atoms, and R ² is alkylene having 3 to 10 carbon atoms and 3 to 10 carbon atoms. Is cycloalkylene, arylene having 6 to 10 carbon atoms, and X and Y are each independently an alkoxy or carboxyl group. The polylactide resin according to claim 1, having an acidity of 3 to 10 meq / kg and a weight average molecular weight of 200,000 to 1,000,000. delete The polylactide resin according to claim 1, which exhibits a weight loss of less than 20% by weight when heated from room temperature to 300 ° C. according to thermogravimetric analysis (TGA). A process for preparing the polylactide resin of claim 1 comprising ring-opening polymerization of a lactide monomer in the presence of an organometallic complex of Formula 1 [Formula 1]

Wherein n 'is an integer from 1 to 15, p is an integer from 0 to 2, a is 0 or 1, M is Sn or Zn, R ¹ and R ³ may be the same or different from each other, Each is hydrogen, alkyl having 3 to 10 carbons, cycloalkyl having 3 to 10 carbon atoms, aryl having 6 to 10 carbon atoms, R ² is alkylene having 3 to 10 carbon atoms, cycloalkylene having 3 to 10 carbon atoms, and 6 to 10 carbon atoms; Is arylene, and X and Y are each independently an alkoxy or carboxyl group. A process for preparing the polylactide resin of claim 1 comprising ring-opening polymerization of a lactide monomer in the presence of a compound of formulas (2) and (3): [Formula 2] [Formula 3]

MX _p Y _2-p Wherein n is an integer from 0 to 15, p is an integer from 0 to 2, M is Sn or Zn, R ¹ and R ³ may be the same or different from each other, and each of hydrogen, carbon of 3 to 10 Alkyl, cycloalkyl having 3 to 10 carbons, aryl having 6 to 10 carbon atoms, R ² is alkylene having 3 to 10 carbon atoms, cycloalkylene having 3 to 10 carbon atoms, arylene having 6 to 10 carbon atoms, X and Y Each independently represents an alkoxy or carboxyl group. The method for producing a polylactide resin according to claim 5 or 6, wherein MX _p Y _2-p is tin (II) 2-ethylhexanoate (Sn (Oct) ₂ ). The compound according to claim 5 or 6, wherein R ¹ represents a monovalent phenyl group substituted with an alkyl group having 1 to 10 carbon atoms, an alkyl group having 3 to 10 carbon atoms, or a cycloalkyl group, and R ² is substituted with an alkyl group having 1 to 10 carbon atoms. The manufacturing method of polylactide resin which shows a bivalent phenylene group, a C3-C10 alkylene group, or a cycloalkylene group. The method of claim 5, wherein the organometallic complex is prepared by a method comprising reacting a compound of Formula 2 and a compound of Formula 3.  [Formula 2] [Formula 3]

MX _p Y _2-p Wherein n is an integer from 0 to 15, p is an integer from 0 to 2, M is Sn or Zn, R ¹ and R ³ may be the same or different from each other, and each of hydrogen, carbon of 3 to 10 Alkyl, cycloalkyl having 3 to 10 carbons, aryl having 6 to 10 carbon atoms, R ² is alkylene having 3 to 10 carbon atoms, cycloalkylene having 3 to 10 carbon atoms, arylene having 6 to 10 carbon atoms, X and Y Each independently represents an alkoxy or carboxyl group. The method of claim 5, wherein the organometallic complex is added in an amount of 0.001 to 0.1 moles with respect to 100 moles of the lactide monomer. The method of claim 6, wherein the compounds of Formulas 2 and 3 are added in an amount of 0.001 to 0.1 moles with respect to 100 moles of lactide monomer, respectively. The method for producing a polylactide resin according to claim 5 or 6, wherein the ring-opening polymerization proceeds in the presence of an initiator containing a hydroxy group-containing compound. The method of claim 12, wherein the initiator is added in an amount of 0.001 to 1 mol based on 100 mol of the lactide monomer. The method for producing a polylactide resin according to claim 5 or 6, wherein the ring-opening polymerization proceeds by bulk polymerization. The method for producing a polylactide resin according to claim 5 or 6, wherein the ring-opening polymerization is performed at a temperature of 120 to 200 ° C for 0.5 to 8 hours. A polylactide resin composition comprising the polylactide resin of claim 1.

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