JP3418070B2 - Aliphatic polyester copolymer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aliphatic polyester copolymer, and more specifically, it has biodegradability and flexibility, and has a high molecular weight. It relates to an aliphatic polyester copolymer having stability.

[0002]

2. Description of the Related Art Conventionally, polyesters used for forming films, fibers, molded articles and the like are high molecular weight polyesters having an average molecular weight of 1 × 10 ⁴ or more. The majority of such high molecular weight polyesters are aromatic polyesters prepared from terephthalic acid and ethylene glycol or 1,4-butanediol, with very few aliphatic polyesters.

Although an aliphatic polyester is a useful polyester having a very high degree of flexibility and biodegradability, a high molecular weight polyester cannot be obtained. Therefore, it is easily decomposed by heat and is practically sufficiently durable. It has not been put to practical use because it is not possible to obtain a material having a high elongation.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to comprise an aliphatic hydroxycarboxylic acid unit, an aliphatic diol unit and an aliphatic dicarboxylic acid unit, and to biodegrade the same. The object of the present invention is to provide an aliphatic polyester copolymer which has strength and elongation and heat stability that can sufficiently withstand practical use because it has flexibility and flexibility and has a high molecular weight.

[0005]

The inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and as a result, have used a catalyst composed of a germanium compound, and have an aliphatic hydroxycarboxylic acid unit and all structural units. A specific amount of α−
It has been found that the inclusion of the hydroxycarboxylic acid unit makes it possible to easily obtain an aliphatic polyester copolymer having a strength and elongation that are sufficiently durable for practical use and thermal stability.

That is, the gist of the present invention is an aliphatic polyester copolymer obtained by a polycondensation reaction in the presence of a catalyst composed of a germanium compound, wherein (1) an aliphatic hydroxycarboxylic acid unit is 30 to 70 mol%. And (2) 15 to 35 mol% of an aliphatic diol unit and 15 to 35 mol% of (3) an aliphatic dicarboxylic acid unit, and at least a part of the aliphatic hydroxycarboxylic acid unit is an α-hydroxycarboxylic acid unit, The ratio of the α-hydroxycarboxylic acid unit is 0.1 to 100 mol% with respect to the aliphatic hydroxycarboxylic acid unit and 40 mol% or less with respect to all the constituent units of the aliphatic polyester copolymer, and the number average molecular weight is Is 1 × 10 ^{4 to} 2 × 10 ⁵ in the aliphatic polyester copolymer.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The aliphatic polyester copolymer of the present invention comprises (1)
It is composed of an aliphatic hydroxycarboxylic acid unit, (2) an aliphatic diol unit, (3) an aliphatic dicarboxylic acid unit, and at least a part of the above aliphatic hydroxycarboxylic acid units is not an α-hydroxycarboxylic acid unit. I won't.

The above-mentioned aliphatic hydroxycarboxylic acid unit is derived from an aliphatic hydroxycarboxylic acid which is an aliphatic compound having at least one hydroxyl group and carboxylic acid group in the molecule.

Specific examples of the aliphatic hydroxycarboxylic acid include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 2-hydroxyisocaproic acid, 2-hydroxy-3,3-dimethylbutyric acid. Two
-Hydroxy-3-methyllactic acid, leucic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, methyllactic acid, caprolactone, valerolactone and the like can be mentioned. Two or more of these aliphatic hydroxycarboxylic acids may be used in combination.

Further, when the aliphatic hydroxycarboxylic acid has optical isomers, any of D-form, L-form and racemic form may be used, and the aliphatic hydroxycarboxylic acid is solid or liquid. Alternatively, it may be an oligomer.

Examples of the above-mentioned α-hydroxycarboxylic acid include compounds represented by the following general formula. In the formula, n represents an integer of 0 to 10.

[0012]

Embedded image HO—CH (C _n H _{2n + 1} ) —COOH

Specific examples of the above α-hydroxycarboxylic acid include lactic acid, glycolic acid, 2-hydroxybutyric acid,
Examples thereof include 2-hydroxycaproic acid and 2-hydroxyisocaproic acid. A particularly suitable α-hydroxycarboxylic acid is lactic acid or an aqueous solution of lactic acid. Two or more of the above α-hydroxycarboxylic acids may be used in combination.

The above-mentioned aliphatic diol unit is derived from an aliphatic diol, and specific examples thereof include ethylene glycol, trimethylene glycol, and 1,3 in which n is 2 to 6.
-Propanediol, 1,4-butanediol, 1,5
-Pentanediol, 1,6-hexanediol, 1,
4-cyclohexanediol etc. are mentioned. A particularly suitable aliphatic diol is 1,4-butanediol. You may use together 2 or more types of said aliphatic diol.

The above-mentioned aliphatic dicarboxylic acid unit is derived from an aliphatic dicarboxylic acid, and specific examples thereof include oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid,
Dodecanedioic acid and the like can be mentioned. Further, the above aliphatic dicarboxylic acid may be a derivative such as a lower alcohol ester or an acid anhydride. Particularly suitable aliphatic dicarboxylic acids are succinic acid and mixtures of succinic acid and adipic acid. Two or more of these aliphatic dicarboxylic acids and their derivatives may be used in combination.

The content of the aliphatic hydroxycarboxylic acid unit is 30 to 70 mol%, preferably 30 to 60 mol%, in all the constituent units of the aliphatic polyester copolymer.
It is more preferably in the range of 30 to 50 mol%.

The content of the α-hydroxycarboxylic acid unit is in the range of 0.1 to 100 mol with respect to 100 mol of the aliphatic hydroxycarboxylic acid unit. On the other hand, it is 40 mol% or less, preferably 30 mol% or less.

If the α-hydroxycarboxylic acid unit exceeds 40 mol%, the thermal stability of the aliphatic polyester copolymer will be deteriorated and not only a high molecular weight polyester copolymer will not be obtained, but also α-hydroxycarboxylic acid will be obtained. Crystals containing a cyclic dimer of an acid as a main component are generated, which deteriorates the yield of the aliphatic polyester copolymer.

The molar ratio of the aliphatic diol unit and the aliphatic dicarboxylic acid unit contained is each in the range of 15 to 35 mol%, preferably 20 to 35 mol%, and more preferably 25 to 35 mol%. Are substantially equal molar ratios. The raw material aliphatic diol and aliphatic dicarboxylic acid are used in excess of 1 to 50% mol, preferably 5 to 20 mol% over the above range, in consideration of the distillative loss in the ester reaction in the production process. It

The aliphatic polyester copolymer of the present invention is
It is obtained by a polycondensation reaction in the presence of a catalyst composed of a germanium compound. Examples of the polycondensation method include, for example,
A melt polycondensation method, a solution polycondensation method, an interfacial polycondensation method and the like can be mentioned. The conditions of the polycondensation reaction can be set conventionally used conditions and are not particularly limited.

Specific examples of the above germanium compound include organic germanium compounds such as germanium oxide and tetraalkoxy germanium, and inorganic germanium compounds such as germanium chloride. From the viewpoint of price and availability, a particularly suitable catalyst is germanium oxide,
Examples thereof include tetraethoxy germanium and tetrabutoxy germanium.

The amount of the germanium catalyst used is usually 5 to 80 based on all the constituent units of the aliphatic polyester copolymer.
The range is 00 ppm, preferably 10 to 5000 ppm. The timing of adding the germanium catalyst is not particularly limited as long as it is before polycondensation, but it may be added at the time of charging the raw materials or at the start of depressurization. It is preferable to add the α-hydroxycarboxylic acid or the aqueous solution thereof at the same time when the raw materials are charged, or to dissolve the α-hydroxycarboxylic acid in advance and add it.

The polycondensation temperature is usually in the range of 150 to 260 ° C, preferably 180 to 230 ° C. The polycondensation time is usually 2 hours or longer, preferably 4 to 15 hours. The degree of reduced pressure during the polycondensation reaction is usually 10 mmHg or less, preferably 2 mmHg or less.

The aliphatic polyester copolymer of the present invention is
Other copolymerizable units can be introduced as long as the effects of the present invention are not impaired. Specific examples of deriving other copolymerizable units include polyhydric alcohols such as trimethylolpropane, glycerin, and pentaerythritol, trimellitic anhydride, trimesic acid, and polycarboxylic acids such as propanetricarboxylic acid or anhydrides thereof. , Malic acid,
Examples thereof include polyhydric hydroxycarboxylic acid of tartaric acid.

The aliphatic polyester copolymer of the present invention is
A number average molecular weight of 1 × 10 ⁴ to 2 is obtained by using a germanium compound as a catalyst, and containing the α-hydroxycarboxylic acid unit in a specific amount based on all the constituent units and the aliphatic hydroxycarboxylic acid unit. × 10 ⁵
And big. As a result, the aliphatic polyester copolymer of the present invention has a large strength and elongation and excellent thermal stability without impairing biodegradability and flexibility.

[0026]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The physical property values in the examples were measured by the following methods.

(1) The number average molecular weight was measured by a GPC device (“PL-10 μ-Mixed” as a sample column).
"8020 model" manufactured by Tosoh Corporation and equipped with an RI detector. The measurement condition is a sample concentration of 0.1
% By weight, eluent chloroform, liquid flow rate 1 mL / min,
The column temperature was 40 ° C.

(2) The composition of the aliphatic polyester copolymer was determined from the area ratio of the spectrum obtained by the ¹ H-NMR method.

Example 1 In a reaction vessel having a capacity of 300 mL equipped with a stirrer, a nitrogen introducing tube, a heating device, a thermometer and an auxiliary agent addition port, 9.1 g of succinic acid, 49.6 g of 1,4-butanediol and ε were prepared. -Captured 57.6 g of caprolactone and 6.3 g of a 90% aqueous lactic acid solution in which 1% by weight of germanium dioxide was dissolved in advance, and reacted for 20 minutes at 180 ° C in a nitrogen atmosphere for 20 m.
The reaction was performed under a reduced pressure of mHg for 1.75 hours. Then, a polycondensation reaction was performed at 220 ° C. for 4 hours under a reduced pressure of 0.5 mmHg.

The number average molecular weight of the obtained aliphatic polyester copolymer was 3.89 × 10 ⁴ . The composition ratio was 31 mol% for succinic acid units, 33 mol% for 1,4-butanediol units, 4 mol% for lactic acid units, and 32 mol% for caprolactone units. When the aliphatic polyester copolymer film was produced by using a tabletop hot press, a flexible film having a high strength and elongation was obtained.

Example 2 23.6 g of succinic acid was placed in a reaction vessel similar to that of Example 1.
1,4-Butanediol 18.9 g, 3-hydroxy-
Charge 31.2 g of n-butyric acid and 25.0 g of 90% lactic acid aqueous solution in which 1% by weight of germanium dioxide was dissolved in advance,
After reacting at 180 ℃ in nitrogen atmosphere for 0.5 hours, 220 ℃
The temperature was raised to 0.5 and the reaction was carried out for 0.5 hours. Then 0.5 mm
The polycondensation reaction was performed for 4 hours under a reduced pressure of Hg.

The number average molecular weight of the obtained aliphatic polyester copolymer was 3.12 × 10 ⁴ . The composition ratio was 20 mol% for succinic acid units, 21 mol% for 1,4-butanediol units, 28 mol% for lactic acid units, and 31 mol% for 3-hydroxy-n-butyric acid units.
When a film of the above-mentioned aliphatic polyester copolymer was prepared using a hot press on a table, a flexible film having a high strength and elongation was obtained.

Comparative Example 1 59.1 g of succinic acid was placed in the same reaction vessel as in Example 1.
After charging 49.6 g of 1,4-butanediol, 57.6 g of ε-caprolactone and 10.0 g of a 90% aqueous lactic acid solution in which 1% by weight of antimony oxide was dissolved in advance, the mixture was reacted at 180 ° C. in a nitrogen atmosphere for 0.5 hours. The temperature was raised to 220 ° C. and the reaction was performed for 0.5 hours. Then, a polycondensation reaction was performed for 4 hours under a reduced pressure of 0.5 mmHg. The resulting aliphatic polyester copolymer has a number average molecular weight of 9.2 × 1.
It was 0 ^{3 and} was a viscous liquid.

Comparative Example 2 23.6 g of succinic acid was placed in the same reaction vessel as in Example 1.
Charge 18.9 g of 1,4-butanediol, 54.1 g of 90% lactic acid aqueous solution and 6.0 g of 90% lactic acid aqueous solution in which 1% by weight of germanium dioxide was dissolved in advance, and react at 180 ° C. for 0.5 hours in a nitrogen atmosphere. Then, the temperature was raised to 200 ° C. and the reaction was performed for 0.5 hours. Then, a polycondensation reaction was performed for 4 hours under a reduced pressure of 0.5 mmHg.

During the polycondensation reaction, white crystals were formed and spilled out of the reaction system. The composition ratio of the obtained aliphatic polyester copolymer was 23 mol% for succinic acid units, 23 mol% for 1,4-butanediol units and 54 mol% for lactic acid units.
Met. Its number average molecular weight was 1.1 × 10 ⁴ , but it was brown and had poor thermal stability.

[0036]

The above-described aliphatic polyester copolymer of the present invention is obtained by using a germanium compound as a catalyst, and the α-hydroxycarboxylic acid unit is converted into all constituent units and aliphatic hydroxycarboxylic acid units. On the other hand, by containing a specific amount, the number average molecular weight is 1 × 10.
^It is as large as ^{4 to} 2 x 10 ⁵ . As a result, the aliphatic polyester copolymer of the present invention has a large strength and elongation and excellent thermal stability without impairing biodegradability and flexibility.

Claims (3)

(57) [Claims] 1. An aliphatic polyester copolymer obtained by a polycondensation reaction in the presence of a catalyst comprising a germanium compound, wherein (1) an aliphatic hydroxycarboxylic acid unit is 30 to 70 mol%, and (2) an aliphatic compound. 15 diol units
35 mol%, (3) aliphatic dicarboxylic acid unit 15-35
Mol%, at least a portion of the aliphatic hydroxycarboxylic acid units are α-hydroxycarboxylic acid units,
The ratio of the α-hydroxycarboxylic acid unit is 0.1 to 100 mol% with respect to the aliphatic hydroxycarboxylic acid unit and 40 mol% or less with respect to all the constituent units of the aliphatic polyester copolymer, and the number average molecular weight is Is 1 × 10 ^{4 to} 2 × 10
^5. An aliphatic polyester copolymer characterized by being ⁵ . 2. The aliphatic polyester copolymer according to claim 1, wherein the α-hydroxycarboxylic acid is a compound represented by the following general formula. ## STR1 ## _{HO-CH (C n H 2n} + 1) -COOH (n in the formula is an integer of 0.) 3. The aliphatic polyester copolymer according to claim 1, wherein the α-hydroxycarboxylic acid is lactic acid.