JP2004315825A - Method for producing aliphatic polyester polymer and aliphatic polyester polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an aliphatic polyester polymer having excellent mechanical properties, in particular, elongation at break, wherein the method is performed at a high polymerization rate and has industrial advantages, and to obtain the aliphatic polyester polymer by the method. <P>SOLUTION: The method for producing the aliphatic polyester polymer comprises polycondensation using, as a reaction material, (i) a mixture of at least one aliphatic dicarboxylic acid selected from aliphatic dicarboxylic acids, diesters and acid anhydrides thereof with an aliphatic diol or (ii) a precondensate of the mixture, and polycondensing the mixture in the presence of a reaction catalyst consisting of a metal-containing transesterification catalyst and a cocatalyst, wherein, as the cocatalyst, at least one phosphorus compound selected from a hydrogen-containing magnesium phosphate, a hydrogen-containing magnesium polyphosphate and a diarylphosphinic acid is used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing an aliphatic polyester-based polymer having excellent mechanical properties, particularly excellent elongation at break, and an aliphatic polyester-based polymer obtained by the method.

Synthetic polymers such as polyolefins and aromatic polyesters are used in large quantities as indispensable materials for daily life.However, these synthetic polymers are not decomposed in the natural environment. With this, environmental problems have become apparent. For this reason, biodegradable plastics are being developed, and aliphatic polyesters are receiving attention as biodegradable polymers.
However, conventional aliphatic polyesters have many problems to be solved in terms of mechanical strength, cost, and the like. For example, polyhydroxybutyrate is a polyester having a high melting temperature and good performance. However, since the difference between the melting temperature and the decomposition temperature is small, it is likely to be thermally decomposed at the time of molding to cause problems such as performance deterioration and odor generation. Also, since it is a polymer produced using microorganisms, productivity is low and cost is high. Polycaprolactone is one of the few aliphatic polyesters currently industrially produced, but its melting temperature of about 60 ° C. limits its use. In addition, hydroxycarboxylic acid polymers are attracting attention as polymers with good biodegradability, and in particular, lactic acid polymers are biocompatible polymers such as those used in bioabsorbable materials, but the manufacturing process is complicated. It is.

  In order to solve the above-mentioned problems relating to the production and performance of aliphatic polyesters, polyesters obtained by polycondensation of aliphatic dicarboxylic acids or derivatives thereof (esters, acid anhydrides, etc.) with glycols have attracted attention. The method for producing this polyester has been known for a long time, and succinic acid, adipic acid, suberic acid, sebacic acid, dodecadicarboxylic acid and the like are used as acids, and ethylene glycol, 1,4-butanediol, and 1,1 are used as glycols. A method using 6-cyclohexanediol, 1,4-cyclohexanedimethanol or the like has been reported. However, all of these polymers have a number average molecular weight of about several thousands, and thus do not have a sufficient mechanical strength that can be formed into films or fibers.

For this reason, many methods for producing polyesters having a large molecular weight and high mechanical strength have been proposed. However, in any of these proposals, there are cases where the production process is increased and the polymer performance is lowered in some cases, and there is no satisfactory method.
According to JP-A-4-189822 and JP-A-4-189823, an aliphatic polyester having a number average molecular weight of about 15,000 is produced from an aliphatic dicarboxylic acid or a derivative thereof and glycol, and this is crosslinked with diisocyanate. To increase the molecular weight. However, this method has problems such as formation of a microgel and deterioration of polymer quality. According to JP-A-5-287041 and JP-A-287042, a polymer having a high molecular weight and a wide molecular weight distribution is obtained by copolymerizing an aliphatic dicarboxylic acid, a glycol and a polyvalent isocyanate. This polymer has a high molecular weight, a high mechanical strength, and has a high melt viscosity due to a wide molecular weight distribution, and is suitable for producing a molded article such as a film. For the same purpose, JP-A-5-287068 discloses a four-component copolymer obtained by adding 3,3,4,4-benzophenonetetracarboxylic anhydride in addition to the three components described above. Japanese Patent Application Laid-Open Publication No. H11-15064 proposes a four-component copolymer to which a polyhydric alcohol such as pentaerythritol is added in addition to the above three. However, these copolymers have problems such as formation of a gel. In addition, JP-A-6-192374 discloses that an aliphatic dicarboxylic acid, a glycol and a polyhydric alcohol or a polyhydric carboxylic acid are used to synthesize a low-molecular-weight aliphatic polyester, and the aliphatic polyester having an isocyanate group at the end thereof. A method has been proposed in which a polyester is reacted to obtain a high molecular weight polymer containing no microgel. However, this method has a disadvantage that the number of manufacturing steps is further increased.

  In a method for producing an aliphatic polyester-based polymer, a general ester exchange reaction catalyst such as titanium tetraisopropoxide is used. However, in the case of this catalyst, the polyesterification reaction rate is still insufficient, and there is a problem of coloring of the obtained polymer. Further, there is a problem to be improved in practical use such as insufficient mechanical properties, particularly breaking elongation, of the obtained polymer for applications such as various films and yarns. Regarding the problem of coloring, US Pat. No. 5,504,148 (1996) proposes a method of increasing the molecular weight by adding phosphoric acid or the like as a coloring inhibitor to a Ti catalyst. However, the reaction rate is still insufficient, and the presence of a phosphorus compound such as phosphoric acid produces by-products such as tetrahydrofuran from the raw material diol (Chemical Encyclopedia, Vol. 7, 850p (Showa 37)). However, the cost is insufficient.

  The present invention provides a method for industrially advantageously producing an aliphatic polyester polymer having excellent mechanical properties, particularly excellent breaking elongation at a practically high polymerization rate, and an aliphatic polyester polymer obtained by the method. To provide

The present inventors have conducted intensive studies to solve the above problems, and as a result, completed the present invention.
That is, according to the present invention, (i) a mixture of at least one aliphatic dicarboxylic acid compound selected from aliphatic dicarboxylic acids, diesters and acid anhydrides thereof, and an aliphatic diol; In a method in which a precondensate of the mixture is used as a reaction raw material and the reaction raw material is subjected to a polycondensation reaction in the presence of a reaction catalyst comprising a metal-containing transesterification catalyst and a cocatalyst, a hydrogen-containing magnesium phosphate is used as the cocatalyst. And a method for producing an aliphatic polyester-based polymer, characterized by using at least one phosphorus compound selected from hydrogen-containing magnesium polyphosphate and diarylphosphinic acid.
Further, according to the present invention, (i) an oxycarboxylic acid-based compound or (ii) a precondensate thereof is used as a reaction raw material, and this reaction raw material is used in the presence of a reaction catalyst comprising a metal-containing transesterification catalyst and a cocatalyst. Wherein at least one phosphorus compound selected from among hydrogen-containing magnesium phosphate, hydrogen-containing magnesium phosphate and diarylphosphinic acid is used as the co-catalyst. A method for producing a polymer is provided.
Further, according to the present invention, there is provided an aliphatic polyester-based polymer obtained by the above-mentioned method, wherein the aliphatic polyester-based polymer contains the metal-containing transesterification catalyst and the co-catalyst. .

  INDUSTRIAL APPLICABILITY The aliphatic polyester-based polymer of the present invention has good mechanical properties, especially elongation at break, for films and the like practically, and can be advantageously used as a film material. In addition, the use of a small amount of a co-catalyst enables the polymerization time to be shortened, and a high molecular weight polymer can be obtained at a practically high polymerization rate.

前記式中、Ｒ¹は炭素数１〜１２、好ましくは１〜１０の二価脂肪族基を示す。二価脂肪族基は、鎖状又は環状のものであることができ、また飽和又は不飽和のものであることができる。さらに、この二価脂肪族基は、その主鎖には、炭素の他、酸素等のヘテロ原子を含有することもできる。本発明で用いる好ましい二価脂肪族基は、炭素数１〜１２、好ましくは１〜１０のエーテル結合を含有していてもよいアルキレン基又はアルケニレン基や、アルキレンオキシ基又はオキシアルキレン基等である。二価脂肪族基の具体例を示すと、−ＣＨ₂−、−Ｃ₂Ｈ₄−、−ＣＨ₂Ｏ−、−ＣＨ₂ＯＣＨ₂−、−Ｃ₃Ｈ₆−、−Ｃ₄Ｈ₈−、−Ｃ₆Ｈ₁₂−、−Ｃ₈Ｈ₁₆−、−Ｃ₁₂Ｈ₂₄−、−Ｃ₁₂Ｈ₂₂−等が挙げられる。
前記一般式（１）において、そのＲ¹¹は、水素、低級アルキル基又はアリール基を示す。低級アルキル基としては、炭素数１〜６、好ましくは１〜４のアルキル基が挙げられる。アリール基としては、炭素数６〜１０、好ましくは６〜８のもの、例えばフェニル基等が挙げられる。
前記脂肪族ジカルボン酸としては、コハク酸、アジピン酸、スベリン酸、セバシン酸、ドデカン酸、ジグリコール酸等が挙げられる。 In order to produce the polymer of the present invention, at least one aliphatic dicarboxylic acid compound selected from aliphatic dicarboxylic acids, esters and acid anhydrides thereof is used as a main reaction material. These are represented by the following general formula (1) (dicarboxylic acid or diester thereof) or (2) (dicarboxylic anhydride), respectively.
R ¹¹ OOC-R ¹ -COOR ¹¹ (1)

In the formula, R ¹ represents a divalent aliphatic group having 1 to 12, preferably 1 to 10 carbon atoms. The divalent aliphatic group can be linear or cyclic, and can be saturated or unsaturated. Further, the main chain of the divalent aliphatic group may contain a hetero atom such as oxygen in addition to carbon. The preferred divalent aliphatic group used in the present invention is an alkylene group or alkenylene group which may have an ether bond having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, or an alkyleneoxy group or an oxyalkylene group. . When showing a specific example of the divalent aliphatic _{group, -CH 2 -, - C 2} H 4 -, - CH 2 O -, - CH 2 OCH 2 -, - C 3 H 6 -, - C 4 H 8 - _{, -C 6 H 12 -, -} C 8 H 16 -, - C 12 H 24 -, - C 12 H 22 - , and the like.
In the general formula (1), R ¹¹ represents hydrogen, a lower alkyl group or an aryl group. Examples of the lower alkyl group include an alkyl group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. Examples of the aryl group include those having 6 to 10 carbon atoms, preferably 6 to 8 carbon atoms, such as a phenyl group.
Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanoic acid, and diglycolic acid.

In producing the polymer of the present invention, an aliphatic diol is used as a main reaction material. This is represented by the following general formula (3).
HO-R ² -OH (3)
In the above formula, R ² represents a divalent aliphatic group having 1 to 12, preferably 2 to 10 carbon atoms. In this case, the divalent aliphatic group can be linear or cyclic, and can be saturated or unsaturated. Further, the main chain of the divalent aliphatic group may contain a hetero atom such as oxygen in addition to carbon. The preferred divalent aliphatic group used in the present invention is an alkylene group or alkenylene group having 1 to 12 carbon atoms, preferably 2 to 10 carbon atoms which may contain an ether bond, or an alkyleneoxy group or an oxyalkylene group. . When showing a specific example of the divalent aliphatic _{group, -CH 2 -, - C 2} H 4 -, - C 3 H 6 -, - C 4 H 8 -, - C 6 H 12 -, - C 8 H 16 _{-, - C 12 H 24 -} , - C 12 H 22 - ( _{dodecenyl), - C 6 H 10 -} ( _{cyclohexenyl), - CH 2 O -,} - CH 2 OCH 2 - and the like.
Specific examples of the aliphatic diol represented by the general formula (3) include, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4. -Cyclohexanedimethanol, polyethylene glycol, polypropylene glycol and the like.

In the present invention, the reaction raw material contains at least two functional groups reactive with the aliphatic dicarboxylic acid compound and / or the aliphatic diol as an auxiliary component, if necessary. At least one compound selected from aliphatic and / or aromatic compounds can be added.
Such auxiliary components include oxycarboxylic acid compounds, carbonates, terephthalic acid compounds, trihydric or higher polyhydric alcohols, polyoxyalkylene glycols, and the like.

前記一般式（４）において、Ｒ³は、炭素数１〜１０、好ましくは２〜８の二価脂肪族基を示す。この場合の価脂肪族基は、前記Ｒ¹及びＲ²に関して示した各種のものであることができる。Ｒ¹²は水素、低級アルキル基又はアリール基を示す。低級アルキル基としては、炭素数１〜６、好ましくは１〜４のアルキル基が挙げられる。アリール基としては、炭素数６〜１０、好ましくは６〜８のもの、例えばフェニル基が挙げられる。
前記オキシカルボン酸（４）としては、グリコール酸、乳酸、α−オキシ酪酸等が挙げられる。また、前記オキシカルボン酸はその２分子が結合した環状ジエステル（ラクチド）であることができる。その具体例としては、グリコール酸から得られるもの（グリコリド）や、乳酸から得られるもの等が挙げられる。 The oxycarboxylic acid-based compounds include compounds represented by the following general formulas (4) and (5).
HO-R ³ -COOR ¹² (4)

In the general formula (4), R ³ represents a divalent aliphatic group having 1 to 10, preferably 2 to 8 carbon atoms. In this case, the valent aliphatic group may be any of those described for R ¹ and R ² . R ¹² represents hydrogen, a lower alkyl group or an aryl group. Examples of the lower alkyl group include an alkyl group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. Examples of the aryl group include those having 6 to 10 carbon atoms, preferably 6 to 8 carbon atoms, such as a phenyl group.
Examples of the oxycarboxylic acid (4) include glycolic acid, lactic acid, and α-oxybutyric acid. Further, the oxycarboxylic acid may be a cyclic diester (lactide) having two molecules bonded thereto. Specific examples thereof include those obtained from glycolic acid (glycolide) and those obtained from lactic acid.

In the general formula (5) representing a lactone compound, R ³ represents a chain or cyclic divalent aliphatic group having 2 to 10 carbon atoms, preferably 2 to 5 carbon atoms. In this case, the divalent aliphatic group includes a saturated or unsaturated alkylene group.
Examples of the lactone include caprolactone, valerolactone, laurolactone and the like.

The carbonate ester is represented by the following general formula (6).
R ¹³ OCOOR ¹⁴ (6)
In the above formula, R ¹³ and R ¹⁴ represent a lower alkyl group or an aryl group. When both R ¹³ and R ¹⁴ are a lower alkyl group, they may be mutually connected to form a ring. Examples of the lower alkyl group include an alkyl group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. Examples of the aryl group include those having 6 to 10 carbon atoms, preferably 6 to 8 carbon atoms, such as a phenyl group.

  The polyhydric alcohol is an aliphatic compound having three or more hydroxyl groups. Such polyhydric alcohols include glycerin, diglycerin, polyglycerin-based compounds, trimethylolpropane, pentaerythritol, a triol type of polyalkylene glycol, furanovoid (polyphenol), and the like. The upper limit of the number of hydroxyl groups contained in the polyhydric alcohol is not particularly limited, but is usually about six.

The polyglycerin-based compound is represented by the following general formula (7).
_{HO- [C 3 H 5 (OR} 4) O] n -H (7)
In the formula, R ⁴ represents hydrogen or an acyl group, and n represents an average degree of polymerization of glycerin. The acyl group includes an aliphatic acyl group represented by the following general formula (8).
R ¹⁵ CO- (8)
In the above formula, R ¹⁵ is an aliphatic group, and has 1 to 20, preferably 1 to 6 carbon atoms. Specific examples include methyl, ethyl, propyl, butyl, hexyl, dodecyl, octadecyl and the like.
The average degree of polymerization n of the glycerin is 2 or more, and the upper limit is about 30. Generally, n is 1-10.

The polyoxyalkylene glycol is represented by the following general formula (9).
HO (AO) _m H (9)
In the above formula, AO represents an alkyleneoxy group having 2 to 4 carbon atoms, and specific examples thereof include ethyleneoxy, propyleneoxy, butyleneoxy, and a mixed alkyleneoxy thereof.
M represents an average degree of polymerization of (AO), and represents a number of 2 to 10, preferably 2 to 5.

  In the present invention, as the auxiliary component, in addition to the above-mentioned compounds, oxypolycarboxylic acids such as malic acid and citric acid, diisocyanate, orthoformate, terephthalic acid, polyethylene terephthalate and the like can be used.

  In the reaction raw material comprising the aliphatic dicarboxylic acid compound and the aliphatic diol used in the present invention, the proportion of the aliphatic diol used is preferably 2 to 1 mol, preferably 1 mol, per 1 mol of the total carboxylic acid component contained in the reaction raw material. Is a ratio of 1.6 to 1.02 mol.

  The use ratio of the oxycarboxylic acid-based compound used in the present invention is such that the mole fraction of the ester portion (oxycarboxylic acid ester portion) derived from the oxycarboxylic acid-based compound with respect to all the ester portions contained in the produced polymer is as follows. The ratio is set to be 0.5 or less, preferably 0.03 to 0.45, and more preferably 0.03 to 0.4.

    The proportion of the carbonate used in the present invention is such that the mole fraction of the ester (carbonate) derived from the carbonate relative to the total ester contained in the polymer to be produced is 0.5 or less, preferably 0%. 0.03 to 0.45, more preferably 0.03 to 0.4.

  The use ratio of the terephthalic acid compound (terephthalic acid, its ester or acid anhydride) used in the present invention is such that the ester portion (terephthalic acid) derived from the terephthalic acid compound with respect to the total ester portion contained in the produced polymer. The molar fraction of the (acid ester portion) is preferably in the range of 0.01 to 0.2, more preferably 0.03 to 0.1.

  The use ratio of the polyoxyalkylene glycol used in the present invention is such that the mole fraction of the ester portion derived from the polyoxyalkylene glycol relative to the total ester portion contained in the produced polymer is 0.5 or less, preferably 0%. 0.03 to 0.45, more preferably 0.03 to 0.4.

  The use ratio of diglycolic acid or an ester thereof used as the auxiliary component of the present invention is such that the molar fraction of the ester portion derived from diglycolic acid (diglycolic acid ester portion) is 0 with respect to the total ester portion contained in the resulting polymer. 0.5 or less, preferably 0.03 to 0.45, more preferably 0.03 to 0.4.

    The use ratio of the polyglycerin compound used in the present invention is such that the molar fraction of the ester portion (ether-containing ester portion) derived from the polyglycerin compound with respect to the total ester portion contained in the produced polymer is 0.0001. To 0.005, preferably 0.001 to 0.004.

  Auxiliary components used for controlling the biodegradability and physical properties of the polymer as required in the present invention (trihydric alcohols such as trimethylolpropane, pentaerythritol and glycerin, and oxy groups such as malic acid and citric acid) And the like.), The mole fraction of the components derived from these auxiliary components (auxiliary component components) is 0.001 to 0.01, preferably the total ester portion contained in the polymerization couple to be formed. Is a ratio that falls within the range of 0.001 to 0.004. In the case of an auxiliary component and a diisocyanate, the molar ratio of the auxiliary component is 0.001 to 0.03, preferably 0.005 to 0.02.

The reaction raw material used in the present invention can be composed of at least one selected from the oxycarboxylic acid compounds represented by the general formulas (4) and (5). The reaction raw material contains, if necessary, at least one selected from aliphatic and / or aromatic compounds containing at least two functional groups reactive with the oxycarboxylic acid compound. can do.
The auxiliary component includes a carbonate ester, a trihydric or higher polyhydric alcohol, a polyoxyalkylene glycol, and the like. Specific examples include those described above.
Further, as other auxiliary components, oxypolycarboxylic acids such as malic acid and citric acid, diisocyanate, orthoformate, terephthalic acid compounds, polyethylene terephthalate, triol type of polyalkylene glycol, and furanovoid (polyphenol) are used. Can be.
The auxiliary component is used for the purpose of controlling the biodegradability and physical properties of the produced polymer. The amount used is preferably such that the molar ratio with respect to all monomer components contained in the resulting polymer is 0.3 or less, preferably 0.2 or less.

In the present invention, a combination of a metal-containing transesterification catalyst and a co-catalyst is used when the reaction raw materials are subjected to a polycondensation reaction. In this case, at least one phosphorus compound selected from hydrogen-containing magnesium phosphate, hydrogen-containing magnesium phosphate and diarylphosphine is used as the co-catalyst.
The hydrogen-containing magnesium phosphate includes magnesium hydrogen phosphate and magnesium dihydrogen phosphate. These phosphates can be hydrates.
The hydrogen-containing magnesium polyphosphate includes a dehydrated condensate of a magnesium phosphate. In this polyphosphate, the degree of condensation (degree of polymerization) is 2 to 10, preferably 2 to 6, and more preferably 2 to 4.
The diarylphosphinic acid includes diphenylphosphinic acid, ditolylphosphinic acid and the like.

  The ratio of the co-catalyst used in the present invention is such that the ratio of the phosphorus compound to the metal-containing transesterification catalyst is 0.01 to 0.1 in terms of the atomic ratio M / P (M: metal) of the metal atom to the phosphorus atom. 8, preferably in the range of 0.2 to 0.5.

  The co-catalyst used in the present invention exhibits an excellent action as a catalyst auxiliary component for producing an aliphatic polyester-based polymer, and is conventionally used as a metal-containing transesterification catalyst such as titanium tetraisopropoxide. The combination has effects such as shortening the polymerization time and suppressing generation of by-products such as tetrahydrofuran, and provides a high-molecular-weight polyester polymer having excellent hydrolysis resistance, which is industrially advantageous.

As the metal-containing transesterification catalyst (esterification catalyst) used in the present invention, conventionally known various catalysts are used.
Examples of such a transesterification catalyst include alkali metals such as lithium and potassium, alkaline earth metals such as magnesium, calcium, and barium; typical metals such as tin, antimony, and germanium; lead, zinc, cadmium, manganese, and cobalt. Transition metals such as nickel, zirconium, titanium and iron, various compounds of metals such as bismuth, niobium, lanthanum, samarium, europium, erbium, ytterbium and other lanthanoid metals, for example, alcoholates, acetylacetonate chelates, acetates, etc. Can be mentioned.

  Specific examples of the typical metal compound include dibutyltin oxide, dibutyltin dilaurate, antimony trioxide, germanium oxide, bismuth carbonate, and bismuth acetate.

  Examples of the rare earth compound include lanthanum acetate, samarium acetate, europium acetate, erbium acetate, and ytterbium acetate.

  In the present invention, it is particularly preferable to use a transition metal-based transesterification catalyst. Specific examples of such transition metal compounds include lead acetate, zinc acetate, zinc acetylacetonate, cadmium acetate, manganese acetate, manganese acetylacetonate, cobalt acetate, cobalt acetylacetonate, nickel acetate, nickel acetylacetonate. Examples include nitrate, zirconium acetate, zirconium acetylacetonate, titanium acetate, tetrabutoxytitanate, tetraisopropoxytitanate, titanium oxyacetylacetonate, iron acetate, iron acetylacetonate, and niobium acetate.

These esterification catalysts may be used alone or in combination of two or more. The catalyst is used in an amount of 10 ^{-7 to} 0.5 mol, preferably 0.005 to 0.3 mol, more preferably 0.1 to 0.5 mol, based on 100 mol of the total amount of the carboxy group-containing compound contained in the reaction raw materials. It is preferable to use it in a ratio of from 0.1 to 0.15 mol. When the amount of the catalyst is less than this range, the reaction does not proceed well and the reaction requires a long time. If the amount exceeds this range, it causes thermal decomposition, cross-linking, coloring, etc. of the polymer during polymerization, and also causes thermal decomposition, etc., during molding of the polymer, which is not preferable.

In one method for producing an aliphatic polyester-based polymer according to the present invention, a reaction raw material is heated in the presence of a transesterification catalyst and its cocatalyst to cause a polycondensation reaction. In this reaction, water and OH-containing compounds (such as alcohols) are by-produced. When the reaction by-product is methanol, the reaction temperature under normal pressure is 100 to 300 ° C., preferably 120 to 300 ° C. 250 ° C. When the by-product is water, the reaction temperature under normal pressure is 130 to 300 ° C, preferably 140 to 250 ° C. The reaction pressure is normal pressure, reduced pressure or slightly increased pressure, but is preferably normal pressure.
In the present invention, by-products generated in the reaction are removed from the reaction system. To this end, the reaction is carried out under conditions of temperature and pressure at which water or OH-containing compounds as by-products are maintained in the gas phase, and the by-products in the gas phase are reduced in pressure in the reaction system. The gas is discharged from the reaction system by flowing nitrogen gas. In addition, the reaction is carried out using a reactor (reactive distillation column) to which a distillation column is connected, and by-products produced by the reaction are continuously discharged from the distillation column.
In such a reaction, in order to efficiently obtain a high-molecular-weight polymer, the reaction proceeds to a certain extent, and when 90% of the calculated amount of by-products (water or alcohol such as methanol) is obtained, the reaction is stopped. It is preferable to carry out polycondensation while removing the aliphatic diol by changing the reaction conditions such as raising the temperature or reducing the pressure. The reaction conditions in this case are conditions in which the aliphatic diol to be eliminated exists as a gas, and can be formed by adjusting the temperature and pressure.

Another method for preferably producing the aliphatic polyester-based polymer of the present invention comprises a pre-polycondensation step (first step) and a high-molecularization step (second step) for increasing the molecular weight of the pre-polycondensate. Is the way.
In the preliminary polycondensation step, the reaction raw materials are subjected to a polycondensation reaction in the presence of a cocatalyst (a phosphorus compound) and a catalyst.
When a reaction material is subjected to a polycondensation reaction in the presence of the catalyst component, the reaction temperature is a temperature at which by-products produced by the reaction are present as a gas in the reaction system. The reaction pressure is normal pressure, reduced pressure or slightly increased pressure, but is preferably normal pressure. By-products generated in this reaction are removed from the reaction system. When the reaction proceeds and 70-99%, preferably 90-99% of the calculated amount of by-product (water or alcohol) in the reaction product is obtained, the reaction temperature is raised and the polycondensation is carried out under reduced pressure. Let it. The preliminary polycondensation time in this case is 1 hour to 5 hours. The co-catalyst component may be charged at the start of the precondensate (oligomer) formation reaction or at the start of the polymerization reaction, but a method in which the co-catalyst component is charged in the presence of a catalyst at the start of the oligomer formation reaction is preferable.

Next, in order to carry out a high molecular weight reaction of the pre-polycondensation reaction product obtained as described above, the reaction is continued with or without adding a transesterification catalyst to the reaction product.
In the high molecular weight process, the aliphatic glycol bonded to the terminal of the low molecular weight condensate is condensed while being eliminated to produce a high molecular weight condensate. More than 10,000 condensates can be produced. The reaction conditions in this case may be any conditions under which the by-produced aliphatic glycol can exist as a gas. This high molecular weight process can be performed in the same apparatus as the reaction apparatus for performing the prepolymerization step or in the main polymerization apparatus having high stirring efficiency. When the same apparatus is used, after the completion of the precondensation reaction, the reaction conditions may be changed, for example, the reaction temperature may be increased and the reaction pressure may be reduced to carry out the condensation reaction of the precondensate.
The reaction pressure is from normal pressure to reduced pressure, but it is preferable to use reduced pressure. When employing reduced pressure, the pressure is generally 0.005 to 5 Torr, preferably 2 Torr or less. The lower limit of the pressure is not particularly limited, but is usually about 0.01 to 1 Torr. The reaction time is about 90 to 600 minutes.

One embodiment of the polymer of the present invention is represented by the following general formula (11)
(—CO—R ¹ —CO—OR ² —O—) (11)
And an ether group-containing ester moiety represented by the following general formula (12)
(-CO-R ³ -O-) (12)
And / or a molar fraction of 0.5 or less, preferably 0.03 to 0.45, more preferably 0.03 to 0.4, and / or the following general formula: (13)
(-OCOO-) (13)
Is contained at a molar fraction of 0.5 or less, preferably 0.03 to 0.45, more preferably 0.03 to 0.4.

Another embodiment of the polymer of the present invention is represented by the following general formula (14)
(-CO-R ³ -O-) (14)
And an oxycarboxylic acid ester moiety represented by the following general formula (15)
(-OCOO-) (16)
Is contained at a molar fraction of 0.5 or less, preferably 0.03 to 0.45, more preferably 0.03 to 0.4.

Still another embodiment of the polymer of the present invention is represented by the following general formula (16):
^{(-CO-R 1 -CO-O} -R 2 -O-) (16)
And a dicarboxylic acid ester moiety represented by the following general formula (17)
^{(-CO-R 1 -CO-O} -R 4 -O-) (17)
(In the formula, R ⁴ is an ether-containing divalent aliphatic group having 4 to 12 carbon atoms, and t represents a number of 0 or 1.)
Is contained at a molar fraction of 0.5 or less, preferably 0.03 to 0.45.

Still another embodiment of the polymer of the present invention is a compound represented by the following general formula (18)
_{(-COC 6 H 4 CO-) (} 18)
The terephthalic acid ester portion represented by the following formula is contained in a molar fraction of 0.001 to 0.2, preferably 0.005 to 0.1.

The polymer of the present invention has a substantially linear structure, or has a branched structure by adding a crosslinking agent to the linear structure as an auxiliary component, and has excellent mechanical properties, particularly excellent elongation at break, Further, they have excellent color tone and preferably have a weight average molecular weight of 80,000 or more. The upper limit of the molecular weight is usually about 300,000. Since the polymer of the present invention is an aliphatic polyester, it has biodegradability, and is also a polymer having good chemical recyclability since raw materials can be recovered by alcoholysis and hydrolysis. .
The polyester-based polymer obtained by the method of the present invention contains the metal-containing transesterification catalyst and co-catalyst used in the reaction, and such a catalyst and co-catalyst may be separated from the polymer. However, its separation is costly, and in the case of the present invention, its content is very small, so that it is advantageous to use it as a product without any particular separation.

Next, the present invention will be described specifically with reference to examples. Various physical property values of the aliphatic polyester were measured by the following methods.
(Molecular weight and molecular weight distribution)
A calibration curve was prepared from standard polystyrene using gel permeation chromatography (GPC), and the weight average molecular weight (Mw), number average molecular weight, and molecular weight distribution (Mw / Mn) were determined. As an eluent, chloroform was used.
(Thermal properties)
The melting temperature and the glass transition point were determined by a differential scanning calorimeter (DSC). The thermal decomposition temperature was determined by a thermogravimetric analyzer (TG).
(Hydrolysis resistance test)
A 25 mm × 25 mm × 0.25 mm film is placed in a constant temperature / humidity bath at 80 ° C. and a relative humidity of 90% to hydrolyze the polymer film for a predetermined number of days (t), and then the weight average molecular weight Mw (t) is measured. Then, Mw (t) / Mw (t = 0) was determined as a measure of hydrolysis resistance from the ratio with the molecular weight Mw (t = 0) before hydrolysis.

Comparative Example 1
180 mmol of succinic acid, 198 mmol of 1,4-butanediol, and 0.12 mmol of titanium tetraisopropoxide were charged into a four-necked flask having a capacity of 100 ml with stirring blades, and the reaction was started at 140 ° C. under a nitrogen atmosphere. The temperature was gradually raised to 230 ° C., and water was allowed to flow out (about 1 hour). Next, the pressure was gradually reduced while stirring, and the reaction was continued at a final ultimate vacuum of about 0.5 Torr for 1 hour and 20 minutes. After the reaction, when the molecular weight of the obtained polymer was measured, it was Mw 154,000 and Mw / Mn was 2.20. Mn was 70,000. The elongation at break was 391%.

Example 1
180 mmol of succinic acid, 198 mmol of 1,4-butanediol, 0.12 mmol of titanium tetraisopropoxide and 0.6 mmol of diphenylphosphinic acid Ph ₂ PO (OH) were placed in a 100 ml four-necked flask with stirring blades. The reaction was started under a nitrogen atmosphere at 140, the temperature was gradually raised to 230 ° C., water was allowed to flow out (about 1 hour), and then the pressure was gradually reduced while stirring, and the final ultimate vacuum was about 0.5 Torr The reaction was continued for 4.3 hours. After the reaction, when the molecular weight of the obtained polymer was measured, it was Mw 102,000 and Mw / Mn was 1.65. Mn was 61,900. The elongation at break of the mechanical properties is shown in Table 1. As shown in FIG. It has been found that the elongation at break useful as a film material is significantly improved.

測定条件：測定温度；２５℃、延伸速度；１０ｍｍ／ｍｉｎ、
サンプルの厚み；０．２５ｍｍ（ＪＩＳ規格 Ｋ７１２７の
試験片タイプ５）

Measurement conditions: measurement temperature; 25 ° C., stretching speed: 10 mm / min,
Sample thickness: 0.25 mm (JIS K7127
Test piece type 5)

Example 2
3626.0 g of succinic acid, 2787.3 g of 1,4-butanediol, 1502.2 g of ε-caprolactone, 139.7 g of diethylene glycol, 4.595 g of titanium tetraisopropoxide, phosphorus in a 10-liter stainless steel reactor with stirring blades 0.893 g of magnesium hydrogen oxyhydrate (MgHPO ₄ .3H ₂ O) was charged, and the molar fraction of the ester portion derived from ε-caprolactone and diethylene glycol relative to the total ester portion: (ε-CL + DEG) × 100 / (SA + CL) ) = 32%), dehydration was started at 140 in a nitrogen atmosphere, the temperature was gradually raised to 240 ° C., water was allowed to flow out (about 5 hours), and then the pressure was gradually reduced while stirring, so that the final ultimate vacuum was reached. The reaction was continued at about 0.5 Torr for 11 hours. After the reaction, when the molecular weight of the obtained polymer was measured, it was Mw 228,000 and Mw / Mn was 2.32. Mn was 96,000. The elongation at break of mechanical properties was 1306%.

Example 3
100 mmol of succinic acid, 105 mmol of 1,4-butanediol, 100 mmol of ε-caprolactone, 0.033 mmol of titanium tetraisopropoxide and Ph ₂ PO (OH ) Was charged with 0.0165 mmol (molar fraction of the ester portion derived from ε-caprolactone based on the total ester portion: ε-CL × 100 / (SA + ε-CL) = 50%), and dehydrated at 140 under a nitrogen atmosphere. After starting, the temperature was gradually raised to 230 ° C., and water was allowed to flow out (about 1 hour). Then, the pressure was gradually reduced while stirring, and the reaction was continued for 5 hours at a final ultimate vacuum of about 0.5 Torr. After the reaction, the molecular weight of the obtained polymer was measured. As a result, Mw was 888,000 and Mw / Mn was 1.63. Mn was 54,000. The elongation at break of mechanical properties was 2246%. It was found that the elongation at break was significantly improved.

Example 4
180 mmol of succinic acid, 198 mmol of 1,4-butanediol, 0.12 mmol of titanium tetraisopropoxide and magnesium hydrogen phosphate hydrate (MgHPO ₄ .3H ₂ O) ), The reaction was started at 140 ° C under a nitrogen atmosphere, the temperature was gradually raised to 240 ° C, and water was allowed to flow out (about 1 hour). Then, the pressure was gradually reduced while stirring, and the reaction was continued for 1 hour and 40 minutes at a final ultimate vacuum of about 0.5 Torr. After the reaction, the molecular weight of the obtained white polymer (including the main catalyst and the co-catalyst, the same applies hereinafter) was measured, and Mw was 191,000 and Mw / Mn was 2.19. A high molecular weight polyester was obtained as compared with Comparative Example 1.

Example 5
Co-catalyst comprising magnesium hydrogen phosphate hydrate (MgHPO ₄ .3H ₂ O), diammonium hydrogen phosphate (NH ₄ ) ₂ HPO ₄ or calcium dihydrogen phosphate CaH ₂ O ₇ P ₂ and titanium tetraisopropoxide A hydrolysis resistance test was performed on polybutylene succinate (PBS) containing the main catalyst and cocatalyst obtained by the same synthesis method as in Example 4 using the catalyst Ti (OisoPr) ₄ , and the results are shown in Table 2. Thus, it was found that polybutylene succinate obtained using magnesium hydrogen phosphate as a co-catalyst was the most excellent in hydrolysis resistance. The order of hydrolysis resistance is as follows: MgHPO ₄ .3H ₂ O / Ti (OisoPr) ₄ > Ti (OisoPr) ₄ > CaH ₂ O ₂ P ₂ / Ti (OisoPr) ₄ > (NH ₄ ) ₂ HPO ₄ / Ti ( OisoPr) ₄ .

  Biodegradable plastics have not only improved practical substances, but also a great problem of stability against atmospheric moisture during storage when commercialized. Magnesium hydrogen phosphate was found to have an excellent effect on hydrolysis resistance as a co-catalyst.

Example 6
When a polybutylene succinate (PBS) copolymer containing 5% of the obtained terephthalic acid unit was subjected to a hydrolysis resistance test using a titanium acetylacetonate catalyst, a small amount of terephthalic acid unit was copolymerized. As a result, Mw (8) / Mw (0) after 8 days was 0.61, and it was found that the hydrolysis resistance was significantly improved.

Claims (11)

  (I) a mixture of at least one aliphatic dicarboxylic acid compound selected from aliphatic dicarboxylic acids, diesters and acid anhydrides thereof with an aliphatic diol, or (ii) a precondensate of the mixture is used as a reaction raw material. And a polycondensation reaction of this reaction raw material in the presence of a reaction catalyst comprising a metal-containing transesterification catalyst and a co-catalyst, wherein the co-catalyst is a hydrogen-containing magnesium phosphate, a hydrogen-containing magnesium phosphate and A method for producing an aliphatic polyester polymer, comprising using at least one phosphorus compound selected from diarylphosphinic acids.   The method according to claim 1, wherein the ratio of the phosphorus compound to the metal-containing transesterification catalyst is in the range of 0.01 to 0.8 in terms of the atomic ratio of the metal atom to the phosphorus atom.   As the reaction raw material, (i) an aliphatic dicarboxylic acid-based compound, an aliphatic diol, and an auxiliary component, and the auxiliary component has reactivity with the aliphatic dicarboxylic acid-based compound and / or the aliphatic diol. 3. The method according to claim 1, wherein a mixture of at least one selected from aliphatic and / or aromatic compounds containing at least two functional groups or (ii) a precondensate of the mixture is used.   The method according to any one of claims 1 to 3, wherein a ratio of the auxiliary component is in a range of 0.5 or less in a molar ratio to all monomer components contained in the produced polymer.   (I) A method in which (i) an oxycarboxylic acid-based compound or (ii) a precondensate thereof is used as a reaction raw material, and the reaction raw material is subjected to a polycondensation reaction in the presence of a reaction catalyst comprising a metal-containing transesterification catalyst and a cocatalyst. And a method for producing an aliphatic polyester polymer, wherein at least one phosphate selected from hydrogen-containing magnesium phosphate, hydrogen-containing magnesium phosphate and diarylphosphinic acid is used as the co-catalyst. .   6. The method according to claim 5, wherein the ratio of the phosphate to the metal-containing transesterification catalyst is in the range of 0.01 to 0.8 in terms of the atomic ratio of the metal atom to the phosphorus atom.   The reaction raw material comprises (i) an oxycarboxylic acid compound and an auxiliary component, wherein the auxiliary component is an aliphatic and / or aromatic compound having at least two functional groups reactive with the oxycarboxylic acid compound. 8. The method according to claim 6, wherein a mixture of at least one member selected from group III compounds or (ii) a precondensate of the mixture is used.   The method according to claim 7, wherein the ratio of the auxiliary component is 0.5 or less in a molar ratio to the oxycarboxylic acid-based compound. The ratio of the metal-containing transesterification catalyst is 10 ^{-7 to} 0.5 mol per 100 mol of the total amount of all carboxyl group-containing compounds contained in the reaction raw material. That way.   The method according to any one of claims 1 to 10, wherein the aliphatic polyester-based polymer has a weight average molecular weight of 80,000 or more.   An aliphatic polyester-based polymer obtained by the method according to any one of claims 1 to 10, comprising the metal-containing transesterification catalyst and the cocatalyst.