JP3374617B2 - Method for producing aliphatic polyester copolymer - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aliphatic polyester copolymer. More specifically, the present invention relates to a method for producing a high molecular weight aliphatic polyester copolymer which 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 biodegradability and having excellent physical properties and melt viscosity required for molding.

[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 5,000 or more, preferably 10,000 or more, and the terminal group is substantially a hydroxyl group. It is described that a high molecular weight aliphatic polyester containing a urethane bond can be obtained by adding a diisocyanate group as a coupling agent to a polyester diol in a molten state above its melting point. 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.

In Japanese Patent Laid-Open No. 5-310898, a glycol component and an aliphatic dicarboxylic acid component are esterified, and the polyester diol produced is esterified in the presence of a catalyst at a temperature of 180 to 230 ° C. and 0.005 to 0. .1m
It has been proposed that a high-molecular weight aliphatic polyester having a number average molecular weight of 25,000 to 70,000 whose end groups are substantially hydroxyl groups is obtained by performing a deglycolization reaction under a high vacuum of mHg. It is industrially difficult to obtain such a high vacuum state, or there is a problem that the cost becomes high.

Further, in JP-A-7-228675, aliphatic polyhydric alcohols, aliphatic polybasic acids and hydroxycarboxylic acids are directly condensed in a reaction mixture containing an organic solvent to give an aliphatic polyester. Although a method for obtaining the same has been proposed, when a solvent is used in this way, a step of purifying the polymer is indispensable, and the reaction time is very long, which is several tens of hours. Absent.

[0006]

An object of the present invention is to have biodegradability and to have excellent physical properties and melt viscosity, which are applicable to various fields such as films, molded articles and fibers.
It is to provide a method for producing a high molecular weight aliphatic polyester copolymer.

[0007]

[Means for Solving the Problems]

[Summary of the Invention] The present invention has been made to solve the above-mentioned problems, and in particular, as a result of studies to increase the melt viscosity required for forming a film of an aliphatic polyester or for molding a molded article, as a result, one When a trifunctional carboxylic acid is used as a component and a desired aliphatic diol component is copolymerized with an aliphatic dicarboxylic acid or a functional derivative thereof, a catalyst composed of a germanium compound is used as the catalyst, and a reaction system is used. It has been found that the coexistence of a bifunctional aliphatic oxycarboxylic acid as an essential component significantly increases the polymerization rate, and as a result, it is possible to easily achieve high molecular weight and high viscosity, and at the same time, to achieve the above object. , What was obtained.

<Summary> That is, the method for producing an aliphatic polyester copolymer according to the present invention is (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid or a functional derivative thereof, and (c) 3 in the presence of a catalyst. When an aliphatic polyester copolymer is produced by reacting a functional carboxylic acid or a functional derivative thereof under a polyester-forming condition, a catalyst composed of a germanium compound is used as the catalyst, and the reaction system is (d) bifunctional. Coexistence of an aliphatic oxycarboxylic acid.

<Effect> Since the aliphatic polyester copolymer obtained by the method of the present invention has a branched component in its structure, it is possible to impart desired properties to a molded product, such as a film, using the branched component. I can. The aliphatic polyester copolymer obtained by the method of the present invention has a large melt viscosity and is advantageous for various moldings such as inflation molding and blow molding.

In the present invention, when an appropriate amount of a bifunctional aliphatic oxycarboxylic acid such as lactic acid is used in the presence of a catalyst composed of a germanium compound, the rate of polymerization is increased, and as a result, a high molecular weight and high viscosity fat is obtained. Group polyester copolymers can be obtained. That is, the polyester copolymer obtained by the present invention has a number average molecular weight of generally 10,000 or more, usually 30,000 or more, and preferably 40,000 or more. It is unexpected that such an effect was obtained by using a catalyst composed of a germanium compound and a bifunctional aliphatic oxycarboxylic acid in combination. Furthermore, the combined use of a trifunctional carboxylic acid or a functional derivative thereof tends to further increase the polymerization rate. This can shorten the polycondensation time, which is industrially advantageous.

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the reaction of (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid or a functional derivative thereof, and (c) a trifunctional carboxylic acid or a functional derivative thereof. Is particularly preferably characterized in that (d) a bifunctional aliphatic oxycarboxylic acid is present when it is carried out by the action of a germanium catalyst. In this invention, “aliphatic” includes “alicyclic”.

<Catalyst> The method for producing the aliphatic polyester copolymer according to the present invention is generally carried out by using a specific raw material (described later).
Is carried out in the presence of a polymerization catalyst composed of a germanium compound. The catalyst composed of a germanium compound used in the present invention may be a mixture of two or more kinds of germanium compounds, and any catalyst that can be used for producing a known polyester copolymer with a germanium compound, for example, titanium or antimony. It can also be used in combination with a metal compound soluble in the reaction system, such as tin, magnesium, calcium, or zinc. As a germanium compound,
For example, there are organic germanium compounds such as tetraalkoxy germanium, or inorganic germanium compounds such as germanium oxide and germanium chloride, and these are particularly preferable. Germanium oxide, tetraethoxygermanium, tetrabutoxygermanium and the like are particularly preferable in terms of price and availability.
The amount of these catalysts used is generally 0.00 based on the amount of monomers used, that is, the total amount of components (a) to (d).
It is 1 to 3% by weight, more preferably 0.005 to 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 it at the same time as the bifunctional aliphatic oxycarboxylic acid when the raw materials are charged, or to dissolve the bifunctional aliphatic oxycarboxylic acid and the aqueous solution thereof, particularly the catalyst, especially germanium oxide, and add it.

<(A) Aliphatic diol> The (a) 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 (I).

[0014]

Embedded image HO—R ¹ —OH (I)

(In the formula, R ¹ is a divalent aliphatic hydrocarbon group,
It preferably has 2 to 11 carbon atoms, and particularly preferably 2 to 6 carbon atoms. R ¹ has been described above to include a cycloalkylene group, and may have a branched chain. Preferred R ¹ 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 1,4-cyclohexanedimethanol. These may be used alone or in a mixture thereof. From the viewpoint of the physical properties of the resulting copolymer, the aliphatic diol is particularly preferably 1,4-butanediol or ethylene glycol.

<(B) Aliphatic dicarboxylic acid or functional derivative thereof> Polyester is obtained by polymerizing an ester bond to form a 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, for a given component (a), the component (b) in the present invention as a carboxyl group donor for forming an ester bond is intended for the various ester bond forming reactions described above. There is a "functional derivative" there.
Are typically lower (C ₁ -C ₃ ) alkyl esters and acid anhydrides. The "functional derivative" is preferably for both of the two carboxyl groups. The aliphatic dicarboxylic acid as the base of the component (b) is preferably one represented by the following formula (II).

[0019]

Embedded image HOOC-R ² —COOH (II)

(In the formula, R ² 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 ² is a cycloalkylene group. the inclusion is a place above, also may have a branched chain preferably R ² is, -. (C
H ₂ ) _m −. However, m represents 0 or an integer of 1 to 11, preferably an integer of 1 to 10).

Preferred specific examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, glutaric acid, adipic acid,
Examples thereof include sebacic acid, suberic acid, dodecanedioic acid, and the like, and functional derivatives thereof include acid anhydrides and lower (C ₁ -C ₃ ) alkyl esters thereof. From the physical properties of the obtained copolymer, the component (b) is preferably succinic acid or succinic anhydride, or a mixture of these with adipic acid. These dicarboxylic acids or functional derivatives may be used in combination within each group and / or between each group.

<(C) Trifunctional Carboxylic Acid or Functional Derivatives Thereof> The term “functional” as used in the present invention relates to ester formation, and therefore, the carboxylic acid of component (c) is trifunctional. That is, that is, one having three carboxylic acids in one molecule. The “functional derivative” referred to as the component (c) has the same definition as the component (b), and is typically a lower (C ₁ -C ₃ ) alkyl ester and an acid anhydride.

The one used in the present invention is an aliphatic carboxylic acid,
Cycloaliphatic carboxylic acid, aromatic carboxylic acid, etc. are not particularly limited, but from the viewpoint that commercially available products are easily available at low cost, trimellitic acid anhydride, trimesic acid, propanetricarboxylic acid, Is preferred. These trifunctional carboxylic acids or their functional derivatives are
They may be used alone or as a mixture.

<(D) Bifunctional aliphatic oxycarboxylic acid>
The bifunctional aliphatic oxycarboxylic acid that can be used in the present invention is not particularly limited as long as it has one hydroxyl group and one carboxylic acid group in the molecule. Aliphatic oxycarboxylic acid corresponding to the aliphatic oxycarboxylic acid unit of 1) is suitable.

[0025]

Embedded image 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. “Chain” is meant to include branched chains. ) More preferably, a compound having a hydroxyl group and a carboxyl group at one carbon atom, especially a compound of formula

[0027]

[Chemical 5]

(In the formula, n is an integer of 0 or 1 or more, preferably 0 or 1 to 10, and more preferably 0 or 1
.About.5). When the (d) bifunctional aliphatic oxycarboxylic acid represented by the above formula is used, the polymerization rate increases. Specific examples of this bifunctional aliphatic oxycarboxylic acid include lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2- Hydroxy-2-methylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, 2
-A ring-opening lactone such as hydroxyisocaproic acid, caprolactone or valerolactone,
Further, lactones such as caprolactone and valerolactone, which ring-open in the polymerization reaction system and act as a bifunctional aliphatic oxycarboxylic acid, or a mixture thereof may be mentioned. When these have optical isomers, D
It may be a body, an L body, or a racemic body, and may have a solid, liquid, or aqueous solution shape. Particularly, lactic acid and an aqueous solution of these are preferable because the polymerization rate at the time of use is particularly remarkable and are easily available. Lactic acid, glycolic acid, etc., are generally commercially available as 50%, 70%, and 90% aqueous solutions, and are easily available.

<Production of Aliphatic Polyester Copolymer> The aliphatic polyester copolymer according to the present invention has a specific content when the components (a) to (c) are reacted in the presence of a catalyst under polyester forming conditions. It is produced by a method which comprises using a catalyst and allowing the component (d) to coexist in the reaction system. Here, "polyester formation conditions" means not only ester bond formation by a simple dehydration reaction but also dealcoholization or transesterification which is another condensation, and addition when the component (b) is an acid anhydride, Further, it means a condition that causes a so-called polycondensation reaction, a deglycolization reaction. Application of reduced pressure to accelerate dehydration, dealcoholization or deglycolization is also included in the category of "polyester production conditions" referred to herein, and use of a catalyst is also one specific example of polyester production conditions. It goes without saying that 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 (a) used is substantially equimolar to the amount of the aliphatic dicarboxylic acid or its functional derivative (b). Therefore, it is usually used in an excess of 1 to 20 mol% with respect to 100 mol of the aliphatic dicarboxylic acid functional derivative. The proportion of the trifunctional carboxylic acid (c) used in the present invention is generally 0.01 to 5 moles, when the number of moles of the aliphatic dicarboxylic acid or its functional derivative is 100 moles. If the addition amount of the trifunctional carboxylic acid is less than 0.01 mol, the effect of the addition is difficult to appear, and if it exceeds 5 mol, the risk of gelation during the reaction increases. A desirable usage rate is 0.
It is 1 to 1.0 mol. The addition timing of the trifunctional carboxylic 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 used in the present invention is the amount of the aliphatic dicarboxylic acid functional derivative 10
It is generally 0.04 to 60 mol, preferably 1 to 20 mol, and more preferably 1 to 10 mol, relative to 0 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 is not particularly limited as long as it is before the polyester forming reaction. For example, (1) when the raw material is charged in the state where the catalyst is previously dissolved in the aqueous aliphatic oxycarboxylic acid solution or The method of adding during the esterification reaction, or (2) the method of adding the catalyst at the same time as the raw material is charged is preferable.

Conditions such as temperature, time and pressure for producing the aliphatic polyester copolymer are not particularly limited as long as the desired polyester copolymer can be obtained, but the temperature is 150 to 260 ° C. , Preferably 180-2
30 degreeC, superposition | polymerization time is 1 hour or more, Preferably it is 2-15 hours, Decompression degree is 10 mmHg or less, More preferably, it is 3 mm.
It is preferable to select from the range of Hg or less.

<Aliphatic Polyester Copolymer> The aliphatic polyester copolymer produced by the method of the present invention is
Component (a) and component (b) are the main polyester constituent members, and when the raw materials are blended at the blending ratio as described above in the production thereof, generally (a) an aliphatic diol unit and ( b) When the molar ratio of the aliphatic dicarboxylic acid or the functional derivative unit thereof is substantially equal and the number of moles of the aliphatic dicarboxylic acid component of the aliphatic polyester copolymer is 100 mol, (d) 2 The functional aliphatic oxycarboxylic acid unit is 0.04 to 60 mol.

These have a structure branched or crosslinked by a part of the trifunctional carboxylic acid unit. That is, 3
The functional carboxylic acid unit forms a crosslinked structure and a branched structure. The component ratio of the trifunctional carboxylic acid unit is generally 0.01 to 5 mol, preferably 0.05 to 1.0, based on the same number of mols (100 mol) of the aliphatic dicarboxylic acid component.
Mol. Even if 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, the present invention is a method for producing an aliphatic polyester copolymer having a relatively large molecular weight, and the number average molecular weight Mn thereof is generally 10,000 or more and 300,000 or less, usually 30,000 or more and 300,000 or less, It is preferably 40,000 or more and 200,000 or less. Further, other copolymer components can be introduced into the aliphatic polyester copolymer produced by the production method of the present invention, as long as the effects of the present invention are not impaired. As the other copolymerization component, an aromatic oxycarboxylic acid such as hydroxybenzoic acid,
Examples thereof include aromatic diols such as bisphenol A, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, trivalent or higher functional polyhydric alcohols, oxycarboxylic acids, and tetrafunctional or higher polycarboxylic acids. It is preferable that these components are 50 mol% or less, particularly 20 mol% or less. In addition, the aliphatic polyester copolymer produced by the production method of the present invention may of course be used in combination with lubricants, waxes, colorants, fillers, stabilizers, crystal nucleating agents, etc., if necessary. .

[0037]

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 Polyester obtained by the desktop hot pressing method was molded into a film having a thickness of 0.30 to 0.37 mm,
The test piece was cut into a piece of cm × 2 cm. The test piece was buried in soil for 3 months, and the biodegradability was visually confirmed.

Example 1 118.1 g of succinic acid (b) and 1,4-butanediol (a) were placed in a reaction vessel having a capacity of 400 ml equipped with a stirrer, a nitrogen inlet tube, a heating device, a thermometer, and an auxiliary agent addition port. ) To 99.
1 g (equivalent to 110 mol per 100 mol of succinic acid),
90% of germanium oxide dissolved in advance by 1% by weight
% Lactic acid (d) aqueous solution 6.3 g (6.3 mol with respect to 100 mol of succinic acid), trimellitic anhydride (c) 0.29
g (0.15 mol per 100 mol of succinic acid), Super Talc SG95 (manufactured by Nippon Talc Co.) as a crystal nucleating agent
Charge 0.18g, 0.5 at 180 ℃ in a nitrogen atmosphere
After reacting for an hour, the temperature was raised to 220 ° C. and the reaction was performed for 0.5 hour. Then, under reduced pressure of 0.5 mmHg, 3
Polymerization was allowed to proceed for a period of time. The obtained polyester was milky white, Mn was 64,700, and Mw was 181,500. The melting point was 105 ° C. Also ¹ H-NM
The introduction rate of lactic acid by R was 6. with respect to 100 mol of succinic acid.
It was 1 mol. The melt viscosity at 190 ° C. and a shear rate of 100 sec ⁻¹ was 12,000 poise. The film obtained by molding the obtained polyester by hot pressing on a table was a tough film to be used in the biodegradability test. In addition, as a result of the biodegradability test, the film after 3 months had many worm-eaten holes, confirming the biodegradability.

Example 2 94.5 g of succinic acid (b) and 29.g of adipic acid (b) were placed in a reaction vessel having a capacity of 400 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 (a) (corresponding to 111 mol based on 100 mol of the total mol of succinic acid and adipic acid), 12.5 g of 50% lactic acid aqueous solution in which 0.5% by weight of germanium oxide was dissolved in advance, and 50 % Lactic acid (d) aqueous solution 3.5 g (the amount of lactic acid added is 8.9 mol based on 100 mol of the total mols of succinic acid and adipic acid),
0.6 g of trimellitic anhydride (c) (0.3 mol based on 100 mol of the total mol of succinic acid and adipic acid)
Was charged and reacted at 185 ° C. for 0.5 hours in a nitrogen atmosphere, then heated to 220 ° C. and reacted for 0.5 hour. Subsequently, a polymerization reaction was carried out for 3 hours under a reduced pressure of 0.5 mmHg. The obtained polyester is milky white, M
n was 62,000 and Mw was 217,000. The melting point was 90 ° C. In addition, the introduction rate of lactic acid by ¹ H-NMR is 100 moles of succinic acid and adipic acid.
It was 8.6 mol with respect to mol. The melt viscosity at 190 ° C. and a shear rate of 100 sec ⁻¹ was 13,500 poise. In addition, as a result of the biodegradability test, the film after 3 months was in a shattered state, and biodegradability was confirmed.

EXAMPLE 3 100.1 g of succinic anhydride (b) and 1,4-butanediol (in a reactor having a capacity of 400 ml equipped with a stirrer, a nitrogen inlet tube, a heating device, a thermometer, and an auxiliary agent addition port) a)
99.1 g (110 per 100 mol of succinic anhydride)
Mol) and germanium oxide in an amount of 1% by weight in advance, 6.3 g of 70% aqueous solution of glycolic acid and 5.8 g of 70% aqueous solution of glycolic acid (d) (succinic anhydride 100
Glycolic acid component (6.3 mol) per mol, trimesic acid (c) 0.4 g (based on 100 mol of succinic anhydride)
0.2 mol) and charged at 185 ° C. in a nitrogen atmosphere.
After reacting for 5 hours, the temperature was raised to 230 ° C. and reacted for 0.5 hour. Subsequently, polymerization was carried out for 3 hours under a reduced pressure of 1 mmHg. The obtained polyester was milky white, Mn was 61,000, and Mw was 186,300. The melting point was 104 ° C. Further, the introduction rate of glycolic acid by ¹ H-NMR is based on 100 mol of succinic acid,
It was 6.0 mol. 190 ° C, shear rate 100 sec
The melt viscosity at ^-1 was 11,000 poise. Further, it was confirmed that the same degree of biodegradability as in Example 1 was confirmed.

Comparative Example 1 59.1 g of succinic acid (b) and 1,4-butanediol (a) were placed in a reaction vessel having a capacity of 400 ml equipped with a stirrer, a nitrogen inlet tube, a heating device, a thermometer, and an auxiliary agent addition port. ) To 49.6
g (110 mol per 100 mol of succinic acid), 0.1 g of trimellitic anhydride (c) (0.15 mol per 100 mol of succinic acid), 6.3 g of an aqueous solution in which 1% by weight of germanium oxide is dissolved in advance. 185 in a nitrogen atmosphere
After reacting at 0 ° C for 0.5 hours, the temperature is raised to 220 ° C,
Reacted 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 milky white, Mn is 9,400, Mw is 22,
It was 200. The melt viscosity at 190 ° C. and a shear rate of 100 sec ⁻¹ was 500 poise or less. When the component (d) is not used, the molecular weight does not increase and the melt viscosity is low.

Comparative Example 2 118.1 g of succinic acid (b) and 1,4-butanediol (a) were placed in a reaction vessel having a capacity of 400 ml equipped with a stirrer, a nitrogen introducing tube, a heating device, a thermometer, and an auxiliary agent addition port. ) To 99.
1 g (110 mol per 100 mol of succinic acid), 0.6 g of trimesic acid (0.3 mol per 100 mol of succinic acid), 6.4 g of lactic acid (6 per 100 mol of succinic acid).
4 mol) and 0.06 g of tetrabutyl titanate were added, and the mixture was reacted at 185 ° 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 for 4 hours under a reduced pressure of 0.5 mmHg. The obtained polyester was milky white, Mn was 9,000, and Mw was 19,800. 190 ℃,
The melt viscosity at a shear rate of 100 sec ^-1 was 500 poise or less.

Comparative Example 3 59. Succinic acid was added to a reaction vessel having a capacity of 400 ml equipped with a stirrer, a nitrogen introducing tube, a heating device, a thermometer, and an auxiliary agent addition port.
1 g, 49.6 g of 1,4-butanediol (110 moles per 100 moles of succinic acid), 0.10 g of pentaerythritol (100 moles of succinic acid moles)
0.15 mol), 3.2 g of lactic acid (6.4 mol per 100 mol of succinic acid) and 0.26 g of stannas octoate were charged, and after reacting at 180 ° C. for 0.5 hours in a nitrogen atmosphere, 220 The temperature was raised to ° C and the reaction was carried out for 0.5 hours. Subsequently, polymerization was carried out for 4 hours under a reduced pressure of 0.5 mmHg. The obtained polyester was off-white, Mn was 8,800, and Mw was 18,000. 190 ℃,
The melt viscosity at a shear rate of 100 sec ^-1 was 1000 poise or less. Thus, when the germanium compound is not used as the catalyst, the molecular weight does not increase and the melt viscosity is low.

[0045]

Industrial Applicability By the production method of the present invention, a high molecular weight aliphatic polyester copolymer effective for various uses such as films, molded articles and fibers is provided. Furthermore, the aliphatic polyester copolymer provided by the production method of the present invention can control the crystallinity by changing the introduction ratio of oxycarboxylic acid units, and at the same time, has biodegradability.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-172425 (JP, A) JP-A-5-271377 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (8)

(57) [Claims] 1. An aliphatic diol (a) in the presence of a catalyst,
(B) Aliphatic dicarboxylic acid or a functional derivative thereof, and (c) a trifunctional carboxylic acid or a functional derivative thereof are reacted under polyester forming conditions to allow the components (a) and (b) to be main polyester constituent members. In producing an aliphatic polyester copolymer having a number average molecular weight of (d) a bifunctional aliphatic oxycarboxylic acid coexisting in the reaction system. Is 10,000 to 300,000, and a method for producing an aliphatic polyester copolymer. 2. The amount of (a) the aliphatic diol used is substantially 100 mol, and (c) the trifunctional carboxylic acid, or (b) 100 mol of the aliphatic dicarboxylic acid or the functional derivative thereof. The use ratio of the functional derivative is 0.
The method according to claim 1, wherein the amount of the (d) bifunctional aliphatic oxycarboxylic acid is 0.04 to 60 mol, and the amount of the (d) bifunctional aliphatic oxycarboxylic acid is 0.04 to 60 mol. 3. The method according to claim 1, wherein (c) the trifunctional carboxylic acid is trimellitic anhydride, trimesic acid, or propanetricarboxylic acid. 4. The (d) bifunctional aliphatic oxycarboxylic acid has the formula: (In formula, n shows 0 or an integer greater than or equal to 1), The method of any one of Claims 1-3. 5. The method according to claim 1, wherein (d) the bifunctional aliphatic oxycarboxylic acid is lactic acid. 6. The (a) aliphatic diol is 1,4-butanediol or ethylene glycol.
5. The method according to any one of 5 above. 7. The component (b) is succinic acid, succinic anhydride or a mixture of these with adipic acid.
6. The method according to any one of 6 above. 8. An aqueous solution of (d) a bifunctional aliphatic oxycarboxylic acid in which germanium oxide as a catalyst is dissolved,
(A) an aliphatic diol, (b) an aliphatic dicarboxylic acid or a functional derivative thereof, and (c) a mixture of a trifunctional carboxylic acid or a functional derivative thereof, and
The method according to any one of claims 1 to 7, wherein (d) is reacted.