JP4696306B2 - Biodegradable polyester and method for producing the same - Google Patents

Description

  The present invention relates to a high molecular weight aliphatic polyester having a novel copolymer structure and a method for producing the same.

  Synthetic polymers such as polyolefins and aromatic polyesters are used in large quantities as raw materials indispensable for daily life, but these synthetic polymers are not decomposed in the natural environment. Environmental problems are becoming apparent. For this reason, biodegradable plastics that decompose into carbon dioxide and water by microorganisms in the environment are being developed, and aliphatic polyesters have attracted attention as biodegradable polymers. Among them, polybutylene succinate produced from succinic acid or a derivative thereof and butanediol is attracting attention because of its excellent melting point and mechanical strength.

  However, since polybutylene succinate alone does not necessarily provide practically sufficient mechanical strength and processability, improvement of physical properties by copolymerization with various polyhydric alcohols, hydroxy acids, etc. has been studied. However, a high molecular weight aliphatic polyester having a novel structure showing higher elongation than a homopolymer by copolymerizing 3-alkoxy-1,2-propanediol with an aliphatic dicarboxylic acid diester and an aliphatic glycol first. Proposed (Patent Documents 1 to 3).

  Furthermore, the present inventors proposed a method capable of shortening the time required to increase the molecular weight by adding a small amount of aspartic acid and carrying out copolymerization as an improved method described in the above patent document. (Patent Document 4).

Japanese Patent No. 3066500 Japanese Patent No. 343802 Japanese Patent No.3521231 Japanese Patent No. 3643875

  The present invention is a further improved development of the above-described high molecular weight aliphatic polyester, a novel high molecular weight aliphatic polyester having a short reaction time until high molecular weight and excellent biodegradability, and its An object is to provide an industrially advantageous production method.

（式中、Ｒ^１は炭素数１〜１２の二価脂肪族基、Ｒ^２は炭素数２〜１２の二価脂肪族基、ｐはポリエステル中に含まれる前記一般式（１）で示されるエステル部のモル分率を示す）
で表されるエステル部Ａと、一般式（２）

（式中、Ｒ^１は炭素数１〜１２の二価脂肪族基、Ｒ^３ はＨまたはポリエステル残基、ｒはポリエステル中に含まれる前記一般式（２）で示されるエステル部のモル分率を示す）
で表されるエステル部Ｂとからなり、かつ 該エステル部Ｂのモル分率ｒの値が０．００１〜０．１０の範囲にあることを特徴とする生分解性高分子量脂肪族ポリエステル。
〈２〉Ｒ^１が（ＣＨ_２）_２で、Ｒ^２が（ＣＨ_２）_４であることを特徴とする〈１〉記載の生分解性高分子量脂肪族ポリエステル。
〈３〉下記一般式（３）

（式中、Ｒ^１は炭素数２〜１２の２価脂肪族基を示し、Ｒ^４はＨまたは炭素数１〜８のアルキル基を示す）
または下記一般式（４）

（式中、Ｒ１は前記と同じ）
で表される脂肪族ジカルボン酸誘導体、あるいはそれらのその混合物と、下記一般式（５）

（式中、Ｒ^２は炭素数２〜１２の２価脂肪族基を示す）
で表される脂肪族グリコールと、ジエタノールアミンとを縮合反応させることを特徴とする〈１〉又は〈２〉に記載の生分解性高分子量脂肪族ポリエステルの製造方法。 In order to solve the above problems, the present inventors have intensively studied the synthesis of a biodegradable polyester having the same thermal properties and weight average molecular weight as the original polymer, and having a reduced polymerization time. It has been found that a novel high molecular weight aliphatic polyester produced by copolymerizing an aliphatic dicarboxylic acid and an aliphatic diol with a small amount of diethanolamine meets the purpose.
That is, according to this application, the following invention is provided.
<1> General formula (1)

(In the formula, R ¹ is a divalent aliphatic group having 1 to 12 carbon atoms, R ² is a divalent aliphatic group having 2 to 12 carbon atoms, and p is represented by the general formula (1) contained in the polyester. Indicates the mole fraction of the ester part)
An ester part A represented by the general formula (2)

(Wherein R ¹ is a divalent aliphatic group having 1 to 12 carbon atoms, R ³ is H or a polyester residue, and r is a mole fraction of the ester moiety represented by the general formula (2) contained in the polyester. Indicate)
A biodegradable high molecular weight aliphatic polyester comprising an ester part B represented by the formula (I) and a molar fraction r of the ester part B in the range of 0.001 to 0.10.
<2> The biodegradable high molecular weight aliphatic polyester according to <1>, wherein R ¹ is (CH ₂ ) ₂ and R ² is (CH ₂ ) ₄ .
<3> The following general formula (3)

(In the formula, R ¹ represents a divalent aliphatic group having 2 to 12 carbon atoms, and R ⁴ represents H or an alkyl group having 1 to 8 carbon atoms.)
Or the following general formula (4)

(Wherein R1 is the same as above)
An aliphatic dicarboxylic acid derivative represented by the following formula or a mixture thereof, and the following general formula (5)

(Wherein R ² represents a divalent aliphatic group having 2 to 12 carbon atoms)
The method for producing a biodegradable high molecular weight aliphatic polyester according to <1> or <2>, wherein the aliphatic glycol represented by the formula is subjected to a condensation reaction with diethanolamine.

  The high molecular weight aliphatic polyester of the present invention exhibits biodegradation characteristics and has a copolymer structure with diethanolamine, so it has the same thermal properties and weight average molecular weight as the original polymer, and also has a high molecular weight. The time until is shortened.

BEST MODE FOR CARRYING OUT THE INVENTION

The biodegradable high molecular weight aliphatic polyester of the present invention is characterized by comprising an ester part A of the general formula (1) and an ester part B of the general formula (2).
In this case, in the general formula (1) showing the ester part A, R ¹ represents a chain or cyclic divalent aliphatic group, and the carbon number thereof is 1 to 12, preferably 2 to 6. Examples of such divalent aliphatic groups include alkylene groups such as methylene, ethylene, propylene, butylene, hexylene, cyclohexanedimethylene and the like. R ² represents a chain or cyclic divalent aliphatic group, and the carbon number thereof is 2 to 12, preferably 2 to 6. Examples of such divalent aliphatic groups include alkylene groups such as methylene, ethylene, propylene, butylene, hexylene, octylene, dodecylene, cyclohexylene, and cyclohexanedimethylene.
In addition, the biodegradable high molecular weight aliphatic polyester of the present invention may be one having an ester moiety represented by the general formula (1) as a main chain, and of course a homopolymer having this as the main chain. The copolymer may be a copolymer partially substituted with other components. Examples of the component forming the copolymer include dicarboxylic acids such as alkanedicarboxylic acid, diglycolic acid, cyclohexanedicarboxylic acid, terephthalic acid, alkanediol, monoglyceride, 3-alkoxy-1,2-propanediol, cyclohexanedimethanol Diols such as, glycolic acid, lactic acid, and hydroxyalkanoic acids derived from Σ-caprolactone.
In addition, diethanolamine may be substituted with an acyl group such as an acetyl group.

In the general formula (2) showing the ester part B, R ¹ is the same as described above, and R ³ represents hydrogen or a polyester residue.
The polyester residue as used herein refers to the general formula (1) starting from the formation of an amide bond by condensation between the amino group of the diethanol component and the dicarboxylic acid derivative represented by the general formula (3) or (4). ) Means a polyester moiety.

In the biodegradable high molecular weight aliphatic polyester of the present invention, the ratio (molar fraction r) of the ester part B in the polyester molecule is 0.001 to 0.10, preferably 0.002 to 0.05.
When the ratio of the ester part B is too large, the three-dimensionalization of the polymer by ethanolamine proceeds and gelation occurs, and the problem of becoming a fragile polymer occurs. Problems such as not changing from the original polymer occur.

  The high molecular weight aliphatic polyester of the present invention can be produced by various methods, and one preferred method thereof is a divalent aliphatic dicarboxylic acid derivative represented by the general formula (3) or (4). In this method, the aliphatic glycol represented by the general formula (5) is subjected to a condensation reaction with diethanolamine.

  Examples of the aliphatic dicarboxylic acid derivative represented by the general formula (3) or (4) include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, diester thereof (dimethyl ester, diethyl ester, diester Propyl ester, dibutyl ester), and anhydrides thereof.

  Examples of the aliphatic diglycol represented by the general formula (5) include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, polyethylene glycol, and polypropylene glycol. Etc. The proportion of the aliphatic glycol used is usually 0.90 to 1.10 mol, preferably 0.95 to 1.05 mol, per mol of the aliphatic dicarboxylic acid derivative.

  The condensation reaction is preferably performed in the presence of a conventionally known transesterification catalyst. When performing the said condensation reaction, it is preferable to carry out reaction by two processes, a precondensation process (1st process) and a high molecular weight process (2nd process). In the precondensation step, a low molecular weight condensate having an aliphatic glycol bonded to the terminal is formed. The number average molecular weight of the condensate is preferably about 500 to 10,000, preferably about 1,000 to 5,000, and the molecular weight can be appropriately adjusted depending on reaction conditions and reaction time. Moreover, the reaction conditions in this case should just be the conditions by which the by-produced hydroxy compound can exist as gas under reaction conditions.

  The high molecular weight forming step is a step of producing a high molecular weight condensate by condensation while detaching the aliphatic glycol bonded to the terminal of the low molecular weight condensate. With this step, the weight average molecular weight is 3 More than 10,000 condensates can be produced. The reaction conditions in this case may be any conditions that allow the by-produced aliphatic glycol to exist as a gas. This high molecular weight process can be performed in the same apparatus as the reaction apparatus in which the precondensation process is performed or in the main polymerization apparatus having good stirring efficiency. When the same apparatus is used, after 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 decreased to perform the condensation reaction of the precondensate.

  The high molecular weight polyester of the present invention has a weight average molecular weight of 30,000 or more, preferably 50,000 or more. In this case, the upper limit of the weight average molecular weight is about 1 million.

  The high molecular weight polyester of the present invention has a copolymer structure derived from diethanolamine represented by the general formula (2) in the molecule, and can be added in a small amount by adding a small amount of diethanolamine or an acylated product thereof. It shortens the time and also has biodegradability.

  Next, the present invention will be specifically described with reference to examples. Various physical properties of the aliphatic polyester were measured by the following methods.

(Molecular weight and molecular weight distribution) A calibration curve is prepared from standard polystyrene using a gel permeation chromatograph (GPC) method, and a number average molecular weight (Mn), a weight average molecular weight (Mw) and a molecular weight distribution (Mw / Mn) are obtained. It was. Note that chloroform was used as the eluent.

(Thermal Properties) Melting temperature and crow transition point were determined by a differential scanning calorimeter (DSC). Moreover, the thermal decomposition temperature was calculated | required with the thermogravimetric analyzer (TG).

Example 1
In a glass reactor with a stirring volume of 100 ml, 21.24 g (0.180 mol) of succinic acid, 16.81 g (0.187 mol) of 1,4-butanediol, 0.056 g (0.53 mmol) of diethanolamine, 25 micron of titanium tetraisopropoxide 1 liter (0.1 mmol) was charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and held for 1 hour, and then pressure reduction was started, and the reaction was continued for 1 hour and 10 minutes at a vacuum degree of 0.2 mmHg. The resulting polymer was white and had Mn 55,100, Mw 146,500 and its Mw / Mn was 2.66. The melting temperature was 115.2 ° C, and the 2% weight loss temperature was 318.5 ° C. The proportion of diethanolamine contained in the polymer is 0.29 mol per 100 mol of the aliphatic carboxylic acid component contained in the polymer.

Example 2
In a glass reactor with a stirring volume of 100 ml, 21.35 g (0.181 mol) of succinic acid, 16.83 g (0.187 mol) of 1,4-butanediol, 0.118 g (1.13 mmol) of diethanolamine, 25 micron of titanium tetraisopropoxide 1 liter (0.1 mmol) was charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and maintained for 1 hour, and then pressure reduction was started, and the reaction was continued for 40 minutes at a vacuum degree of 0.2 mmHg. The resulting polymer was white and had Mn 55,600, Mw 306,000, and its Mw / Mn was 5.51. The melting temperature was 114.9 ° C., and the 2% weight loss temperature was 308.6 ° C. The proportion of diethanolamine contained in this polymer is 0.62 mol per 100 mol of the aliphatic carboxylic acid component contained in the polymer.

Example 3
In a glass reactor with a stirring volume of 100 ml, 21.29 g (0.180 mol) of succinic acid, 16.81 g (0.187 mol) of 1,4-butanediol, 0.211 g (2.01 mmol) of diethanolamine, 25 micron of titanium tetraisopropoxide 1 liter (0.1 mmol) was charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and held for 1 hour, and then pressure reduction was started, and the reaction was continued for 15 minutes at a vacuum degree of 0.2 mmHg. The resulting polymer was white and had Mn 12,500, Mw 291,100, and its Mw / Mn was 23.3. The melting temperature was 112.4 ° C., and the 2% weight loss temperature was 309.1 ° C. The proportion of diethanolamine contained in the polymer is 1.10 moles per 100 moles of the aliphatic carboxylic acid component contained in the polymer.

Example 4
In a glass reactor with a stirring volume of 100 ml, 21.23 g (0.180 mol) of succinic acid, 16.86 g (0.187 mol) of 1,4-butanediol, 0.312 g (1.82 mmol) of diethanolamine triacetate, 25 of titanium tetraisopropoxide Microliter (0.1 mmol) was charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and maintained for 1 hour, and then pressure reduction was started, and the reaction was continued for 1 hour 30 minutes at a vacuum degree of 0.2 mmHg. The resulting polymer was white and had Mn 38,800, Mw 139,000, and its Mw / Mn was 3.59. The melting temperature was 115.2 ° C, and the 2% weight loss temperature was 322.8 ° C. The proportion of diethanolamine contained in this polymer is 1.01 mole per 100 moles of the aliphatic carboxylic acid component contained in the polymer.

Comparative Example 1
A glass reactor with a stirring blade with a capacity of 100 ml was charged with 21.25 g (0.180 mol) of succinic acid, 16.89 g (0.188 mol) of 1,4-butanediol, and 25 microliters (0.1 mmol) of titanium tetraisopropoxide. Under a nitrogen atmosphere, the temperature was raised to 160 ° C., and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and maintained for 1 hour, and then pressure reduction was started, and the reaction was continued for 3 hours at a vacuum degree of 0.2 mmHg. The resulting polymer was white and had Mn 76,500, Mw 142,000 and its Mw / Mn was 1.86. The melting temperature was 114.9 ° C., and the 2% weight loss temperature was 308.1 ° C.

Example 5
In a glass reactor with a stirring volume of 100 ml, succinic acid 21.27 g (0.180 mol), 1,4-butanediol 15.96 g (0.177 mol), batyl alcohol 3.09 g (8.97 mmol), diethanolamine 0.125 g (1.19 mmol) ), 25 microliters (0.1 mmol) of titanium tetraisopropoxide were charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and maintained for 1 hour, and then pressure reduction was started, and the reaction was continued for 2 hours and 50 minutes at a vacuum degree of 0.2 mmHg. The resulting polymer was milky white and had Mn 60.300, Mw 251,000, and its Mw / Mn was 4.17. The melting temperature was 108.9 ° C., and the 2% weight loss temperature was 315.0 ° C. The proportion of diethanolamine contained in this polymer is 0.66 mol per 100 mol of the aliphatic carboxylic acid component contained in the polymer.

Comparative Example 2
In a glass reactor with a stirring volume of 100 ml, succinic acid 21.27 g (0.180 mol), 1,4-butanediol 15.96 g (0.177 mol), batyl alcohol 3.10 g (9.0 mmol), titanium tetraisopropoxide 25 Microliter (0.1 mmol) was charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and held for 1 hour, and then pressure reduction was started, and the reaction was continued for 7 hours at a vacuum degree of 0.2 mmHg. The polymer obtained was milky white and had Mn 97,100, Mw 187,800, and its Mw / Mn was 1.94. The melting temperature was 107.9 ° C., and the 2% weight loss temperature was 328.1 ° C.

Example 6
In a glass reactor with a stirring volume of 100 ml, 21.24 g (0.180 mol) of succinic acid, 15.93 g (0.177 mol) of 1,4-butanediol, 0.97 g (9.15 mmol) of 3-methoxy-1,2-propanediol ), 0.182 g (1.73 mmol) of diethanolamine and 25 microliters (0.1 mmol) of titanium tetraisopropoxide, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and maintained for 1 hour, and then pressure reduction was started, and the reaction was continued for 45 minutes at a vacuum degree of 0.2 mmHg. The resulting polymer was white and had Mn 42,400, Mw 192,300, and its Mw / Mn was 4.54. The melting temperature was 111.3 ° C., and the 2% weight loss temperature was 316.0 ° C. The proportion of diethanolamine contained in this polymer is 0.96 mol per 100 mol of the aliphatic carboxylic acid component contained in the polymer.

Comparative Example 3
In a glass reactor with a stirring volume of 100 ml, succinic acid 21.25 g (0.180 mol), 1,4-butanediol 15.92 g (0.177 mol), 3-methoxy-1,2-propanediol 0.96 g (9.05 mmol) ), 25 microliters (0.1 mmol) of titanium tetraisopropoxide were charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and maintained for 1 hour, and then pressure reduction was started, and the reaction was continued for 4 hours at a vacuum degree of 0.2 mmHg. The resulting polymer was white and had Mn 81,100, Mw 141,500 and its Mw / Mn was 1.74. The melting temperature was 112.5 ° C., and the 2% weight loss temperature was 323.1 ° C.

Example 7
In a glass reactor with a stirring volume of 100 ml, succinic acid 21.27 g (0.180 mol), 1,4-butanediol 16.70 g (0.186 mol), caprolactone 4.09 g (35.9 mmol), diethanolamine 0.185 g (1.76 mmol) Then, 25 microliters (0.1 mmol) of titanium tetraisopropoxide was charged, the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and maintained for 1 hour, and then pressure reduction was started, and the reaction was continued for 1 hour 30 minutes at a vacuum degree of 0.2 mmHg. The resulting polymer was white and had Mn38,900, Mw 173,900 and its Mw / Mn was 4.47. The melting temperature was 97.6 ° C, and the 2% weight loss temperature was 332.6 ° C. The proportion of diethanolamine contained in this polymer is 0.98 mole per 100 moles of the aliphatic carboxylic acid component contained in the polymer.

Comparative Example 4
In a glass reactor with a stirring volume of 100 ml, 21.28 g (0.180 mol) of succinic acid, 16.84 g (0.187 mol) of 1,4-butanediol, 4.12 g (36.2 mmol) of caprolactone, 25 micron of titanium tetraisopropoxide 1 liter (0.1 mmol) was charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water was distilled off for 1 hour. The reaction temperature was gradually raised to 230 ° C. and maintained for 1 hour, and then pressure reduction was started, and the reaction was continued for 4 hours at a vacuum degree of 0.2 mmHg. The resulting polymer was white and had Mn87,200, Mw 156,000, and its Mw / Mn was 1.79. The melting temperature was 100.9 ° C, and the 2% weight loss temperature was 322.0 ° C.

Claims (3)

General formula (1)

(In the formula, R ¹ is a divalent aliphatic group having 1 to 12 carbon atoms, R ² is a divalent aliphatic group having 2 to 12 carbon atoms, and p is represented by the general formula (1) contained in the polyester. Indicates the mole fraction of the ester part)
An ester part A represented by the general formula (2)

(Wherein R ¹ is a divalent aliphatic group having 1 to 12 carbon atoms, R ³ is H or a polyester residue, and r is a mole fraction of the ester moiety represented by the general formula (2) contained in the polyester. Indicate)
A biodegradable high molecular weight aliphatic polyester comprising an ester part B represented by the formula (I) and a molar fraction r of the ester part B in the range of 0.001 to 0.10. The biodegradable high molecular weight aliphatic polyester according to claim 1, wherein R ¹ is (CH ₂ ) ₂ and R ² is (CH ₂ ) ₄ . The following general formula (3)

(In the formula, R ¹ represents a divalent aliphatic group having 2 to 12 carbon atoms, and R ⁴ represents H or an alkyl group having 1 to 8 carbon atoms.)
Or the following general formula (4)

(Wherein R1 is the same as above)
An aliphatic dicarboxylic acid derivative represented by the following formula or a mixture thereof, and the following general formula (5)

(Wherein R ² represents a divalent aliphatic group having 2 to 12 carbon atoms)
The method for producing a biodegradable high molecular weight aliphatic polyester according to claim 1, wherein the aliphatic glycol represented by the formula is subjected to a condensation reaction with diethanolamine.