JP5120944B2 - Biodegradable high molecular weight aliphatic 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 have improved the method described in the above-mentioned patent document by adding a small amount of aspartic acid or diethanolamine to carry out copolymerization, thereby shortening the time to increase the molecular weight. Proposed (Patent Documents 4 and 5).

  On the other hand, in recent years, in order to cope with the future depletion problem of petroleum resources, it has been studied to produce chemical products and polymers using biomass, which is a renewable resource, as a raw material. The US Department of Energy has systematically investigated chemical products that can be synthesized from biomass resources, and selected the 12 most promising chemicals by screening. Among them, it is expected to be used as a new polyester raw material. 2,5-furandicarboxylic acid has been selected (Non-patent Document 1), and the present inventors can easily react 2,5-furandicarboxylic acid diester by reacting biomass-derived galactaric acid with an aliphatic alcohol. Proposed a method of synthesizing (Patent Document 6).

Japanese Patent No. 3066500 Japanese Patent No. 343802 Japanese Patent No.3521231 Japanese Patent No. 3643875 JP 2008-24825 A Japanese Patent Application 2006-310143 DOE report Top Value Added Chemicals from Biomass 2004 PNNL / DOE

  The present invention introduces a 2,5-furandicarboxylic acid derivative, which is a biomass-derived chemical product, into polybutylene succinate, which exhibits excellent properties as a biodegradable plastic, thereby improving mechanical strength, particularly elongation at break. It is an object of the present invention to provide a novel biodegradable high molecular weight aliphatic polyester having excellent processability and an industrially advantageous production method for the biodegradable high molecular weight aliphatic polyester.

（式中、Ｒ^１は（ＣＨ_２）_２、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^２は炭素数２〜１２の二価脂肪族基、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を含有し、
エステル部Ｂのモル分率ｒの値が０．００１〜０．０３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^２が（ＣＨ_２）_４であることを特徴とする〈１〉に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（ＣＨ_２）_２を示し、Ｒ^４はＨまたは炭素数１〜８のアルキル基を示す）で表わされる脂肪族ジカルボン酸、またはその酸無水物と、下記一般式（４）

（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、下記一般式（５）

（式中、Ｒ^５はＨまたは炭素数１〜８のアルキル基を示す）
で表わされる2,5-フランジカルボン酸誘導体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。 As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.
That is, this application provides the following invention.
<1> General formula (1)

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

(In the formula, R ² represents a divalent aliphatic group having 2 to 12 carbon atoms, and r represents the molar fraction of the ester moiety represented by the general formula (2) contained in the polyester).
Containing an ester part B represented by
The value of the molar fraction r of the ester part B is 0.001 to 0.00. A biodegradable high molecular weight aliphatic polyester characterized by being in the range of 03 .
<2> ^{R 2} is _{(CH 2) 4} a biodegradable high molecular weight aliphatic polyester according to <1>, characterized in that.
<3> The following general formula (3)

(Wherein R ¹ represents (CH ₂ ) ₂ , R ⁴ represents H or an alkyl group having 1 to 8 carbon atoms), or an acid anhydride thereof, and the following general formula ( 4)

(Wherein R ² represents a divalent aliphatic group having 2 to 12 carbon atoms)
An aliphatic glycol represented by the following general formula (5)

(Wherein R ⁵ represents H or an alkyl group having 1 to 8 carbon atoms)
The method for producing a biodegradable high molecular weight aliphatic polyester according to <1> or <2>, wherein a condensation reaction is performed with a 2,5-furandicarboxylic acid derivative represented by the formula:

  The high molecular weight aliphatic polyester of the present invention exhibits biodegradation characteristics, has the same thermal properties and weight average molecular weight as the original polymer, is excellent in mechanical strength, particularly elongation at break, and is a raw material derived from biomass. Effective use is intended.

（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^２は炭素数２〜１２の二価脂肪族基、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を含有することを特徴とする。 The novel biodegradable high molecular weight aliphatic polyester according to the present invention is
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)

(In the formula, R ² represents a divalent aliphatic group having 2 to 12 carbon atoms, and r represents the molar fraction of the ester moiety represented by the general formula (2) contained in the polyester).
It contains the ester part B represented by these.

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. p represents the molar fraction of the ester moiety represented by the general formula (1) contained in the polyester, and is 1-r.
In the general formula (2) showing the ester part B, R ² is the same as described above. r is usually in a ratio of 0.0005 to 0.30 mol, preferably 0.001 to 0.20 mol, more preferably 0.005 to 0.03 mol, per mol of the aliphatic dicarboxylic acid unit. When the proportion of the 2,5-furandicarboxylic acid derivative used is greater than the previous range, the resulting polymer (polycondensate) does not increase in polymerization degree, and a fragile polymer is produced, which is not preferable.

  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 aliphatic polyester of the present invention exhibits biodegradation characteristics, has the same thermal properties and weight average molecular weight as the original polymer, is excellent in mechanical strength, particularly elongation at break, and is a raw material derived from biomass. Effective use is intended.

（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）で表わされる脂肪族ジカルボン酸、またはその酸無水物と、下記一般式（４）

（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、下記一般式（５）

（式中、Ｒ^５はＨまたは炭素数１〜８のアルキル基を示す）
で表わされる2,5-フランジカルボン酸誘導体とを縮合反応させることにより製造することができる。 The biodegradable high molecular weight aliphatic polyester of the present invention is, for example,
The following general formula (3)

(Wherein 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 an acid anhydride thereof And the following general formula (4)

(Wherein R ² represents a divalent aliphatic group having 2 to 12 carbon atoms)
An aliphatic glycol represented by the following general formula (5)

(Wherein R ⁵ represents H or an alkyl group having 1 to 8 carbon atoms)
It can be produced by a condensation reaction with a 2,5-furandicarboxylic acid derivative represented by the formula:

  Examples of the aliphatic dicarboxylic acid derivative represented by the general formula (3) include aliphatic dicarboxylic acids such as succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, and esters and acid anhydrides thereof. It is done.

  Examples of the aliphatic diol represented by the general formula (4) include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol and the like.

  Examples of the 2,5-furandicarboxylic acid derivative represented by the general formula (5) include 2,5-furandicarboxylic acid, dimethyl 2,5-furandicarboxylate, diethyl 2,5-furandicarboxylate, 2 2,5-furandicarboxylate dipropyl, 2,5-furandicarboxylate dibutyl, 2,5-furandicarboxylate dihexyl, 2,5-furandicarboxylate dioctyl, and the like.

  The condensation reaction according to the present invention is preferably carried out in the presence of a conventionally known transesterification catalyst. In the reaction, the reaction temperature is 100 to 300 ° C, preferably 120 to 270 ° C. The reaction pressure can be reduced pressure, normal pressure or slightly increased pressure (0.5 kg / cm 2 G or less), preferably normal pressure or reduced pressure.

When the condensation reaction is performed, the reaction is preferably performed in two steps, a precondensation step (first step) and a high molecular weight step (second step).
In the precondensation step, a low molecular weight condensate having an aliphatic diol bonded to the terminal is formed. The number average molecular weight of the condensate is preferably 5000 to 10,000, and the molecular weight can be appropriately adjusted depending on the reaction conditions and reaction time.
In the high molecular weight step, the aliphatic diol bonded to the terminal of the low molecular weight condensate is condensed while desorbing to form a high molecular weight condensate. This step has a number average molecular weight of 10,000. The above condensate can be produced. The reaction conditions in this case may be any conditions that allow the by-produced aliphatic diol to exist as a gas. This high molecular weight process can be carried out in the same apparatus as the reactor for carrying out the precondensation process or a 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.

  In order to increase the polymerization rate of the high molecular weight polyester of the present invention, it is effective to add a small amount of an aspartic acid derivative or diethanolamine.

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

  (Thermal properties) Melting temperature and glass 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, 21.2 g (0.180 mol) of succinic acid, 17.0 g (0.189 mol) of 1,4-butanediol, 0.485 g (1.81 mmol) of dibutyl 2,5-furandicarboxylate, Titanium tetraisopropoxide (25 microliters, 0.1 mmol) was charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water and 1-butanol were 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 4 hours at a vacuum degree of 0.5 mmHg. The resulting polymer was white and had Mn 92,300, Mw 156,700, and its Mw / Mn was 1.70. The melting temperature was 112.9 ° C, and the 2% weight loss temperature was 326.2 ° C. The ratio of 2,5-furandicarboxylic acid contained in this polymer is 1.0 mole per 100 moles of the aliphatic carboxylic acid component contained in the polymer.
When the mechanical strength was measured, the elastic modulus was 190 MPa, the upper yield point stress was 27.4 MPa, the break point stress was 56.3 MPa, and the elongation at break was 73%.

Comparative Example 1
A glass reactor with an agitating 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 homopolymer was white and had Mn 76,500, Mw 142,000, its Mw / Mn was 1.86, its melting temperature was 114.9 ° C, and its 2% weight loss temperature was 308.1 ° C.
When the mechanical strength was measured, the elastic modulus was 284 MPa, the upper yield point stress was 30.2 MPa, the fracture point stress was 30.8 MPa, and the elongation at break was 289%.

Example 2
In a glass reactor with an inner volume of 100 ml with stirring blades, 20.6 g (0.175 mol) of succinic acid, 16.9 g (0.187 mol) of 1,4-butanediol, 1.45 g (3.62 mmol) of dibutyl 2,5-furandicarboxylate, Titanium tetraisopropoxide (25 microliters, 0.1 mmol) was charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water and 1-butanol were 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 30 minutes at a vacuum degree of 0.5 mmHg. The resulting polymer was light yellow with Mn 74,600, Mw 123,200, and its Mw / Mn was 1.65. The melting temperature was 113.8 ° C., and the 2% weight loss temperature was 317.6 ° C. The ratio of 2,5-furandicarboxylic acid contained in the polymer is 2.0 moles per 100 moles of the aliphatic carboxylic acid component contained in the polymer.
When the mechanical strength was measured, the elastic modulus was 186 MPa, the upper yield stress was 26.4 MPa, the stress at break was 54.1 MPa, and the elongation at break was 710%.

Example 3
In a glass reactor with a stirring volume of 100 ml, 20.8 g (0.176 mol) of succinic acid, 16.9 g (0.187 mol) of 1,4-butanediol, 0.970 g (5.41 mmol) of dibutyl 2,5-furandicarboxylate, Titanium tetraisopropoxide (25 microliters, 0.1 mmol) was charged, and the temperature was raised to 160 ° C. in a nitrogen atmosphere, and water and 1-butanol were 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 0.5 mmHg. The resulting polymer was light yellow with Mn 70,000, Mw 117,500, and its Mw / Mn was 1.68. The melting temperature was 112.8 ° C., and the 2% weight loss temperature was 333.8 ° C. The ratio of 2,5-furandicarboxylic acid contained in the polymer is 3.0 moles per 100 moles of the aliphatic carboxylic acid component contained in the polymer.
Further, the mechanical strength was measured. The elastic modulus was 188 MPa, the upper yield point stress was 27.4 MPa, the break point stress was 40.3 MPa, and the elongation at break was 488%.

Claims (3)

General formula (1)

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

(In the formula, R ² represents a divalent aliphatic group having 2 to 12 carbon atoms, and r represents the molar fraction of the ester moiety represented by the general formula (2) contained in the polyester).
Containing an ester part B represented by
The value of the molar fraction r of the ester part B is 0.001 to 0.00. A biodegradable high molecular weight aliphatic polyester characterized by being in the range of 03 . The biodegradable high molecular weight aliphatic polyester according to claim 1, wherein R ² is (CH ₂ ) ₄ . The following general formula (3)

(Wherein R ¹ represents (CH ₂ ) ₂ , R ⁴ represents H or an alkyl group having 1 to 8 carbon atoms), or an acid anhydride thereof, and the following general formula ( 4)

(Wherein R ² represents a divalent aliphatic group having 2 to 12 carbon atoms)
An aliphatic glycol represented by the following general formula (5)

(Wherein R ⁵ represents H or an alkyl group having 1 to 8 carbon atoms)
The method for producing a biodegradable high molecular weight aliphatic polyester according to claim 1 or 2, wherein a condensation reaction is performed with a 2,5-furandicarboxylic acid derivative represented by the formula: