JP3387304B2 - Method for producing high molecular weight aliphatic polyester copolymer having amide bond - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aliphatic polyester copolymer having an amide bond. More specifically, the present invention relates to a method for producing a high molecular weight aliphatic polyester copolymer containing an amide bond that can be molded by a general-purpose plastic molding machine such as injection molding, blow molding and extrusion molding. According to the method of the present invention, it is possible to provide a high molecular weight aliphatic polyester copolymer having an amide bond, which has both excellent physical properties and biodegradability.

[0002]

2. Description of the Related Art High molecular weight polyesters having a number average molecular weight of 10,000 or more, which have hitherto been used for molding films, fibers and other molded articles, are PEs made from aromatic polyesters such as terephthalic acid and ethylene glycol.
It was no exaggeration to say that it was limited to T, or PBT made from terephthalic acid and 1,4-butanediol. On the other hand, the reason why the practical application of the aliphatic polyester was extremely difficult is that the melting point of the aliphatic polyester is relatively low, and the number average molecular weight of the aliphatic polyester is 15 in the polycondensation reaction which is generally known. It is difficult to obtain 000 or more, and even if obtained, the number average molecular weight is 1 which is easily decomposed by heat and is generally easy to obtain.
For example, about 10,000 copolymers could not provide sufficient strength for practical use.

Further, in JP-A-4-189822 and JP-A-5-287043, the number average molecular weight is 50.
A urethane bond is added to a polyester diol having a hydroxyl group of 00 or more, preferably 10,000 or more, and a terminal group of which is substantially a hydroxyl group, by adding a diisocyanate group as a coupling agent in a molten state at the melting point or higher. It is described that a high molecular weight aliphatic polyester containing is obtained. However, as far as the inventors of the present invention are aware, when an aliphatic polyester containing a urethane bond is molded by a general-purpose plastic molding method, there are problems such as coloring and generation of microgel depending on conditions. Further, JP-A-7-102061 describes an aliphatic polyester having an ester structure ratio of 30 to 70% and an amide structure ratio of 70 to 30%, all of which are yellow. It is colored and its use is limited.

[0004]

The object of the present invention is to have an amide bond having physical properties which are applicable to various fields such as films, molded articles and fibers, and which have practically no problem and biodegradability. It is to provide a method for producing a high molecular weight aliphatic polyester copolymer.

[0005]

[Means for Solving the Problems]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and provide an aliphatic polyester having an amide bond that has biodegradability and can withstand practical use.
When an aliphatic dicarboxylic acid or a functional derivative thereof is copolymerized with an aliphatic diol component using an amino acid as a component of polyester in the presence of a catalyst composed of a germanium compound, a bifunctional aliphatic oxycarboxylic acid or a functional compound thereof is used. The present invention was obtained by discovering that the coexistence of a derivative as an essential component significantly increases the polymerization rate and, as a result, makes it possible to easily attain a high molecular weight and at the same time achieve the above object.

<Summary> That is, according to the present invention, in the presence of a catalyst,
(A) an aliphatic dicarboxylic acid or a functional derivative thereof,
A method for producing an aliphatic polyester copolymer having an amide bond in which the component (a) and the component (b) are the main polyester constituents by reacting (b) an aliphatic diol and (c) an amino acid under polyester forming conditions. At
A high molecular weight aliphatic polyester copolymer having an amide bond characterized in that the catalyst is a germanium compound catalyst and (d) a bifunctional aliphatic oxycarboxylic acid or a functional derivative thereof coexists in the reaction system. The present invention provides a manufacturing method of.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, when the reaction of (a) an aliphatic dicarboxylic acid or a functional derivative thereof, (b) an aliphatic diol and (c) an amino acid is carried out by the action of a germanium catalyst, d) The presence of a bifunctional aliphatic oxycarboxylic acid or its derivative. In this invention, “aliphatic” includes “alicyclic”.

<(A) Aliphatic dicarboxylic acid or functional derivative thereof> Polyester is obtained by polymerizing an ester bond to form a high molecular weight polymer, and an ester bond is formed between a hydroxyl group and a carboxyl group. It goes without saying that the ester forming reaction between these both functional groups is dehydration of the hydroxyl group and the carboxyl group or dealcoholation of the hydroxyl group and the carboxylic acid ester, that is, ester exchange, or the hydroxyl group and the carboxylic acid. It is also well known that it occurs by addition with an anhydride.

Therefore, the component (a) in the present invention as a carboxyl group donor for forming an ester bond is targeted for various ester bond forming reactions described above with respect to a given component (b) (details will be described later). The "functional derivative" referred to therein is typically a lower alkyl ester and an acid anhydride. The "functional derivative" is preferably for both of the two carboxyl groups.

The aliphatic dicarboxylic acid as the base of the component (a) is preferably one represented by the following formula (I).

[0011]

Embedded image HOOC-R ¹ —COOH (I)

(In the formula, R ¹ is a direct bond or a divalent aliphatic hydrocarbon group, preferably having 2 to 11 carbon atoms, particularly preferably 2 to 6 carbon atoms. R ¹ is a cycloalkylene group. the inclusion is a place above, also may have a branched chain preferably R ¹ is, -. (C
H ₂ ) _m −. However, m represents 0 or an integer of 1 to 11, preferably 0 or an integer of 1 to 6).

Preferred specific examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, glutaric acid, adipic acid,
Sebacic acid, suberic acid, dodecanedioic acid, etc. are mentioned, and these functional anhydrides are mentioned as a functional derivative. From the physical properties of the resulting copolymer, the component (a) is preferably succinic acid or succinic anhydride, or a mixture thereof with adipic acid and / or adipic anhydride. These dicarboxylic acids or functional derivatives may be used in combination within each group and / or between each group.

<(B) Aliphatic diol> The (b) aliphatic diol used in the present invention is an aliphatic compound in the above meaning and is a compound having two hydroxyl groups. Preferred specific examples thereof Is represented by the following formula (II).

[0015]

## STR00003 ## HO--R ² --OH (II)

(In the formula, R ² is a divalent aliphatic hydrocarbon group,
It preferably has 2 to 11 carbon atoms, and particularly preferably 2 to 6 carbon atoms. As described above, R ² includes a cycloalkylene group, and R ² may have a branched chain. Preferred R ² is — (CH ₂ ) _n —, and n is an integer of 2 to 11, preferably 2 to 6.)

The aliphatic diol which can be used in the present invention is not particularly limited, but specific examples thereof include ethylene glycol, triethylene glycol, 1,3-propanediol, 1,4-butanediol and 1,5-. Mention may be made of pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol and 1,6-cyclohexanedimethanol. These may be used alone or in a mixture thereof. From the viewpoint of the physical properties of the obtained copolymer, aliphatic diol, 1,4-butanediol or ethylene glycol is preferable, and 1,4-butanediol is particularly preferable.

<(C) Amino Acid> The amino acid used in the present invention is not particularly limited as long as it has at least one amino group and one carboxyl group in the molecule. It also includes those in which a carboxyl group is bound in the same molecule to form a ring. Further, it may have a hydroxyl group.

The amino acid as the component (c) is preferably an aliphatic amino acid from the viewpoint of biodegradability. Further, from the nature of the obtained polymer, bifunctional and trifunctional types are preferable.

From the viewpoint that commercially available products are easily available at low cost, in the bifunctional type, alanine, glycine, leucine, valine, isoleucine, aminocaproic acid, or cyclic bodies such as ε-caprolactam and laurolactam, Examples of the trifunctional type include serine, threonine, lysine, arginine, asparagonic acid, and glutamic acid. When optical isomers are present in these, they may be in the D-form, L-form, or racemic form, and may be in the form of solid, liquid, or aqueous solution.

<(D) Bifunctional aliphatic oxycarboxylic acid or functional derivative thereof> The bifunctional aliphatic oxycarboxylic acid or functional derivative thereof usable in the present invention includes:
There is no particular limitation as long as it has one hydroxyl group and one carboxylic acid group in the molecule. The "functional derivative" referred to here is one that is opened during the polymerization reaction to act as a bifunctional aliphatic oxycarboxylic acid. In the present invention, an aliphatic oxycarboxylic acid corresponding to the aliphatic oxycarboxylic acid unit of the following formula (III) is suitable.

[0022]

## STR00004 ## HO-R ³ -COOH (III)

(In the formula, R ³ is a divalent aliphatic hydrocarbon group,
It is preferably a divalent aliphatic hydrocarbon group having 1 to 11 carbon atoms, particularly preferably 1 to 6 carbon atoms. Although it is clear from the above that R ³ may include a cycloalkylene group, a chain hydrocarbon is preferable. "Chained"
Shall include branched chains. )

More preferably, a compound having a hydroxyl group and a carboxyl group at one carbon atom, especially a compound having the formula:

[0025]

[Chemical 5] (In the formula, n is 0 or an integer of 1 or more, preferably 0 or 1 to 10, and more preferably 0 or 1 to 5). (D) 2 represented by the above formula
The use of functionalized aliphatic oxycarboxylic acids increases the rate of polymerization.

Specific examples of the bifunctional aliphatic oxycarboxylic acid include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid and 2 -Hydroxycaproic acid,
2-hydroxyisocaproic acid, 3-hydroxybutyric acid,
Ring-opening lactones such as 4-hydroxybutyric acid, 2-methyllactic acid, or caprolactone;
Examples thereof include lactones such as caprolactone and valerolactone that open a ring in the polymerization reaction to act as a bifunctional aliphatic oxycarboxylic acid, or a mixture thereof.

When optical isomers exist in these,
It may be a D-form, an L-form, or a racemic form, and may have a solid, liquid, or aqueous solution shape. Preferably, lactic acid, which markedly increases the polymerization rate during use,
Glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxycaproic acid, 2-hydroxyisocaproic acid and aqueous solutions thereof are preferred. Particularly preferred are lactic acid and lactic acid aqueous solution, which are easily available.
As the lactic acid aqueous solution, 50%, 70%, and 90% aqueous solutions are generally commercially available, and are easily available.

<Production of Aliphatic Polyester Copolymer> In the present invention, when the above components (a) to (c) are reacted under the conditions for producing polyester, a catalyst composed of a germanium compound is used, and It is produced by a method comprising coexisting the component (d) in the reaction system.

Here, the "polyester forming conditions" mean
First, not only the ester bond formation by a simple dehydration reaction, but also other condensation dealcoholization or transesterification, addition when the component (b) is an acid anhydride, and further a deglycolization reaction called a so-called polycondensation reaction are carried out. It means the conditions that cause it. Use of an azeotropic agent and / or application of reduced pressure to accelerate dehydration or deglycolization is also included in the category of "polyester production conditions" referred to herein, and use of a catalyst is also one of polyester production conditions. This is a specific example. Needless to say, the “polyester forming condition” means a condition for forming a polyester by repeating such ester bond formation. Therefore, when the ester forming is a condensation, the “polyester forming condition” is not important. Will mean condensation. In addition, in the case of the addition of the diol to the dicarboxylic acid anhydride, the reaction of the first hydroxyl group is addition, but the reaction of the second hydroxyl group with the second carboxyl group produced by this reaction is condensation. Therefore, the term "polycondensation" as used in the present invention includes polyester production by addition / condensation to an acid anhydride.

The amount of the aliphatic diol (b) used is substantially equimolar to the amount of the aliphatic dicarboxylic acid or its functional derivative (a). Therefore, the amount is generally 1 to 50 mol%, preferably 5 to 30 mol%, that is, 100 to 150 mol, preferably 105, relative to 100 mol of the aliphatic dicarboxylic acid or its functional derivative. ~ 1
It is common to use 30 moles.

The proportion of the amino acid (c) used in the present invention is generally 0.01 to 30 when the number of moles of the aliphatic dicarboxylic acid or its functional derivative is 100 moles.
It is a mole. If the amount of the trifunctional aliphatic oxycarboxylic acid added is less than 0.01 mol, the effect of the addition is unlikely to appear, and if it exceeds 30 mol, coloration is likely to occur during the reaction. A preferred use ratio is 0.1 to 20 mol, particularly 0.1 to 10 mol.
The timing of adding the amino acid is not particularly limited as long as it is before the polyester is formed, and it is convenient to add it at the time of charging the raw materials, but it may be added during the esterification reaction.

The amount of the bifunctional aliphatic oxycarboxylic acid or its functional derivative (d) used in the present invention is generally 0.04 to 60 mol, preferably 100 mol of the aliphatic dicarboxylic acid functional derivative. Is 1 to 20 mol, more preferably 3 to 10 mol. If the amount of the bifunctional aliphatic oxycarboxylic acid is too small, the effect of the present invention is difficult to appear, and if it is too large, the crystallinity tends to be lost, which is not preferable in molding.

The timing of addition of the bifunctional aliphatic oxycarboxylic acid or its functional derivative is not particularly limited as long as it is before the polyester forming reaction. For example, (1) a state in which a catalyst is previously dissolved in an aliphatic oxycarboxylic acid solution. It is preferable to add the catalyst at the time of charging the raw materials or during the esterification reaction, or (2) add the catalyst at the same time as the raw materials are charged.

The method for producing an aliphatic polyester copolymer having an amide bond according to the present invention is generally carried out by using the above raw materials in the presence of a polymerization catalyst containing a germanium compound.
The catalyst comprising a germanium compound used in the present invention may be a mixture of two or more germanium compounds, and any catalyst that can be used for producing a known polyester with a germanium compound, for example, titanium, antimony, It can also be used in combination with a metal compound soluble in the reaction system such as tin, magnesium, calcium and zinc. As a germanium compound,
For example, organic germanium compounds such as tetraalkoxy germanium, or inorganic germanium compounds such as germanium oxide and germanium chloride. Germanium oxide, tetraethoxygermanium, tetrabutoxygermanium and the like are particularly preferable in terms of price and availability.

The amount of these catalysts used is generally 0.001 to 3% by weight, more preferably 0.005 to 5% by weight, based on the amount of monomers used, that is, the total amount of components (a) to (d).
1.5% by weight. The catalyst may be added at any time before the polyester is formed, but may be added at the time of charging the raw materials or at the start of depressurization.
It is particularly preferable to add the catalyst simultaneously with the bifunctional aliphatic oxycarboxylic acid at the time of charging the raw materials, or to add the catalyst dissolved in the bifunctional aliphatic oxycarboxylic acid and its aqueous solution.

The conditions such as temperature, time and pressure for producing the aliphatic polyester copolymer having an amide bond are as follows:
The conditions are not particularly limited as long as the target polyester copolymer is obtained, but the temperature is 150 to 260 ° C., preferably 180 to 230 ° C., the polymerization time is 1 hour or more, preferably 2 to 15 hours, and the degree of vacuum is Is preferably 10 mmHg or less, more preferably 2 mmHg or less.

<Aliphatic Polyester Copolymer Having Amide Bond> The aliphatic polyester copolymer produced by the production method of the present invention comprises the components (a) and (b) as main polyester constituent members. Therefore, if the raw materials are blended in the above-described blending ratio in the production thereof, generally, the molar ratio of (a) the aliphatic dicarboxylic acid and its functional derivative unit to (b) the aliphatic diol unit is substantially And when the number of moles of the aliphatic dicarboxylic acid unit is 100 moles, the (c) amino acid unit is 0.
01 to 30 mol, preferably 0.1 to 20 mol, particularly preferably 0.1 to 10 mol, and (d) the bifunctional aliphatic oxycarboxylic acid unit is 0.04 to 60 mol, preferably 1
-20 mol, more preferably 3-10 mol.

The above copolymer contains an amide bond in the molecular chain by the addition of the amino acid component (c). When the amino acid is trifunctional or more, the resulting aliphatic polyester copolymer having an amide bond has a branched or crosslinked structure. That is, a trifunctional amino acid unit forms a crosslinked structure and a branched structure. Even when the trifunctional component (c) is copolymerized, the polyester copolymer according to the present invention is fusible and belongs to the category of thermoplastic resins.

Further, according to the present invention, an aliphatic polyester copolymer having an amide bond having a large molecular weight can be produced, and its number average molecular weight Mn is 10,000 or more, but generally 10,000 or more and 300,000 or less, usually It is 30,000 or more and 300,000 or less.

In addition, other copolymerization components can be introduced into the aliphatic polyester copolymer having an amide bond according to the production method of the present invention, as long as the effects of the present invention are not impaired. Other copolymerizable components include aromatic oxycarboxylic acids such as hydroxylbenzoic acid, aromatic diols such as bisphenol A, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, or trifunctional or higher functional aliphatic oxycarboxylic acids. , Aliphatic polyols, aliphatic polycarboxylic acids, aromatic polycarboxylic acids, and the like. It is preferable that these components are 50 mol% or less, particularly 20 mol% or less.

The amide bond-containing aliphatic polyester copolymer obtained by the production method of the present invention is prepared by injection molding,
By general-purpose plastic molding methods such as blow molding and extrusion molding, films, laminated films,
Sheet, board, stretched sheet, monofilament, multifilament, non-woven fabric, flat yarn, staple, crimped fiber, streak tape, split yarn, composite fiber,
It can be used for various molded products such as blow bottles and foams.

Of course, in practical use, a nucleating agent, a lubricant, waxes, a coloring agent, a filler, a stabilizer and the like can be used in combination if necessary. Further, the amide bond-containing high molecular weight aliphatic polyester copolymer according to the present invention has biodegradability and has the property of being decomposed by natural bacteria in 2 to 12 months, which causes a problem of natural environmental pollution. It is a very useful polymer for waste treatment because it does not exist and its calories are small. Therefore, shopping bags, garbage bags, agricultural films, cosmetic containers,
It is used for detergent containers, bleach containers, fishing lines, fishing nets, ropes, tying materials, surgical threads, sanitary cover stock materials, cold storage boxes, cushion materials, etc.

[0043]

EXAMPLES The following examples serve to explain the present invention more specifically. The present invention is not limited to these examples as long as the gist thereof is not exceeded. The characteristic values in the examples are measured by the following methods.

(1) Number average molecular weight (Mn), weight average molecular weight (Mw) Gel permeation chromatography (GP)
It was measured by the C) method. The sample was dissolved in chloroform and measured by polystyrene conversion using a Tosoh HLC-8020 type GPC device. Column is PLgel
-10 μ-MIX was used. (2) Polymer composition The composition was calculated from the area ratio of the spectrum obtained by ¹ H-NMR. (3) Thermal properties Heating rate 16 ° C by differential scanning calorimetry (DSC) method
/ Min in a nitrogen atmosphere to measure the melting point. (4) Biodegradability test: From the obtained polyester copolymer containing an amide bond, a thickness of 0.
Make a film of 30-0.37mm and add 2cm
A test piece was prepared by cutting it into 2 cm. The test piece was immersed in soil for 3 months, and the biodegradability was visually confirmed.

Example 1 118.1 g of succinic acid (a) and 1,4-butanediol (b) were placed in a reaction vessel having a capacity of 200 ml equipped with a stirrer, a nitrogen inlet tube, a heating device, a thermometer, and an auxiliary agent addition port. ) To 99.
1 g, 90% DL lactic acid (d) aqueous solution 6.3 g (succinic acid 10
6.3 mol), DL alanine (c) 2.
7 g (3.0 mols per 100 mols of succinic acid) was charged and reacted at 180 ° C. for 0.5 hours in a nitrogen atmosphere, then heated to 220 ° C. and reacted for 0.5 hours. Subsequently, a polymerization reaction was carried out under a reduced pressure of 0.5 mmHg for 5.5 hours. The obtained polyester is milky white, M
n was 28,300 and Mw was 58,300. The melting point was 113 ° C. Further, the introduction rate of lactic acid by ¹ H-NMR was 6.3 moles and the introduction rate of alanine was 2.9 moles relative to 100 moles of succinic acid. A film was prepared from this polymer by hot pressing on a table, and a tough film was obtained. As a result of the biodegradability test, many worm-eaten holes were observed in the film after 3 months, and biodegradability was confirmed.

Example 2 94.5 g of succinic acid (a) and 29.adipic acid (a) were placed in a reaction vessel having a capacity of 200 ml equipped with a stirrer, a nitrogen inlet tube, a heating device, a thermometer, and an auxiliary agent addition port. 0g, 1,4-
100 g of butanediol (b), 12.5 g of a 50% L lactic acid aqueous solution in which 0.5% by weight of germanium oxide was dissolved in advance, and 3.5 g of an L lactic acid (d) aqueous solution (total mol number of succinic acid and adipic acid: 100 mol) Against this, the amount of lactic acid added is 8.9 mol), and aspartic acid (c) 0.8 g
(0.6 mol per 100 mol of the total mols of succinic acid and adipic acid) was charged and reacted at 185 ° C. for 0.5 hours in a nitrogen atmosphere, then the temperature was raised to 230 ° C. and 0.5
Reacted for hours. Subsequently, a polymerization reaction was carried out for 3 hours under a reduced pressure of 0.5 mmHg. The obtained polyester is milky white, Mn is 58,000, Mw is 170,
It was 000. The GPC peak is rather broad and the presence of branches is presumed. The melting point was 90 ° C. Also
^The introduction rate of lactic acid by ¹ H-NMR was 8.2 mol based on 100 mol of succinic acid. A film was prepared from this polymer by hot pressing on a table, and a tough film was obtained. Further, as a result of the biodegradability test, the film after 3 months was in a shattered state, and biodegradability was confirmed.

Comparative Example 1 59.1 g of succinic acid (a) and 1,4-butanediol (b) were placed in a reaction vessel having a capacity of 200 ml equipped with a stirrer, a nitrogen inlet tube, a heating device, a thermometer, and an auxiliary agent addition port. ) To 49.6
g, DL alanine (c) 5.6 g (6.3 mol per 100 mol of succinic acid), and tetrabutoxy germanium 0.2 g were charged, and after reacting at 185 ° C. for 0.5 hours in a nitrogen atmosphere, 220 The temperature was raised to 0 ° C. and the reaction was performed for 0.5 hours. Subsequently, a polymerization reaction was carried out for 4 hours under a reduced pressure of 0.5 mmHg. The obtained polyester is waxy and milky white, Mn is 8,400 and Mw is 17,2.
It was 00. This polymer could not be formed into a film by a desktop hot pressing method.

[0048]

INDUSTRIAL APPLICABILITY The present invention does not use a solvent such as an organic solvent (water which may be used when dissolving a catalyst composed of a germanium compound is removed during the polyester forming reaction). It is possible to efficiently produce an aliphatic polyester copolymer having a high molecular weight amide bond. The aliphatic polyester copolymer having an amide bond obtained by the method of the present invention has a high molecular weight and physical properties that pose no practical problems. Further, since the copolymer has a branch in the molecular chain, the melt viscosity is increased, which makes it suitable for molding such as hollow molding and film molding. Further, the copolymer is biodegradable.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-62091 (JP, A) JP-A-1-167329 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 69/00-69/50

Claims (8)

(57) [Claims] 1. A component (a) and a component (b) which are obtained by reacting (a) an aliphatic dicarboxylic acid or a functional derivative thereof, (b) an aliphatic diol and (c) an amino acid in the presence of a catalyst under conditions for forming a polyester. In the method for producing an aliphatic polyester copolymer having an amide bond whose component is the main polyester constituent, the catalyst is a germanium compound catalyst, and the reaction system comprises (d) a bifunctional aliphatic oxycarboxylic acid. Alternatively, a method for producing a high molecular weight aliphatic polyester copolymer having an amide bond, which is characterized in that a functional derivative thereof coexists. 2. The use ratio of (b) aliphatic diol is 100 to 150 mol, and the use ratio of (c) amino acid is 0.01 to 30 per 100 mol of (a) aliphatic dicarboxylic acid or its functional derivative. Mol, (d) the proportion of the bifunctional aliphatic oxycarboxylic acid or its functional derivative used is 0.0
The method according to claim 1, which is 4 to 60 mol. 3. An aqueous solution of (d) a bifunctional aliphatic oxycarboxylic acid or a functional derivative thereof in which a catalyst is dissolved,
(A) an aliphatic dicarboxylic acid or a functional derivative thereof,
The method according to claim 1, wherein the reaction is carried out by adding to the mixture of (b) the aliphatic diol and (c) the amino acid. 4. The method according to claim 1, wherein the amino acid (c) is aspartic acid. 5. The (d) bifunctional aliphatic oxycarboxylic acid or a functional derivative thereof has the formula: (In formula, n shows 0 or an integer greater than or equal to 1), The method of any one of Claims 1-4. 6. The method according to claim 1, wherein (d) the bifunctional aliphatic oxycarboxylic acid or the functional derivative thereof is lactic acid. 7. The (b) aliphatic diol is 1,4-butanediol or ethylene glycol.
6. The method according to any one of 6 above. 8. The component (a) is succinic acid, succinic anhydride or a mixture of these and adipic acid.
The method according to any one of 1.