JPH11130852A - Method for producing aliphatic polyester copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aliphatic polyester having good productivity and biodegradability. SOLUTION: In producing an aliphatic polyester copolymer by reacting (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid or a derivative thereof, and (c) a bifunctional aliphatic oxycarboxylic acid, a reaction system is used. A method for producing an aliphatic polyester copolymer having a number average molecular weight of 10,000 to 200,000, characterized by coexisting (d) below. (D) Formula (I)
A trifunctional polyol represented by the formula

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 method such as an injection molding method, a hollow molding method and an extrusion molding method. More specifically, it has excellent physical properties and melt viscosity required for molding, and has good productivity,
The present invention also relates to a method for producing an aliphatic polyester copolymer having excellent biodegradability.

[0002]

2. Description of the Related Art Conventionally, high molecular weight polyesters having a number average molecular weight of about 10,000 or more, which have been used for molding films, fibers and other molded articles, are made of aromatic polyesters such as PE made from 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 practical use of aliphatic polyesters was extremely difficult because of the relatively low melting point of aliphatic polyesters and the number average molecular weight of 15, It is difficult to obtain a compound having a number average molecular weight of 1 or more, which is difficult to obtain, is easily decomposed even if obtained, and is generally easy to obtain.
It was found that practically sufficient strength could not be obtained with about 10,000 copolymers.

[0003] Further, JP-A-4-189822 and JP-A-5-287043 disclose that the number average molecular weight is 5,000 or more, preferably 10,000 or more.
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 whose terminal group is substantially a hydroxyl group in a molten state at or above its melting point. It is described. However, as far as the present inventors know, aliphatic polyesters containing urethane bonds have problems such as coloring and generation of microgels depending on conditions when molded by a general-purpose plastic molding method.

The present inventors have previously described Japanese Patent Application Laid-Open No. 8-25968.
In Japanese Patent Publication No. 0, an aliphatic diol, an aliphatic dicarboxylic acid or a functional derivative thereof is copolymerized with a bifunctional aliphatic oxycarboxylic acid and a trifunctional polyhydric alcohol, so that the melt viscosity is large and the melt viscosity is large compared to the number average molecular weight. However, a method for producing an aliphatic polyester copolymer having a large weight average molecular weight was proposed, but the productivity was still insufficient. Also, this aliphatic polyester copolymer had a low biodegradability rate.

In general, it is known that it is effective to copolymerize a polyfunctional polyol to form a crosslinked structure in order to increase the melt viscosity of the aliphatic polyester copolymer (WO96 / 19521, JP-A-9-77
850). However, even when 1,2,6-hexanetriol, glycerin, trimethylolpropane and the like exemplified in these publications are used in combination, the polymerization rate was not always sufficiently high.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high molecular weight aliphatic polyester having excellent physical properties, melt viscosity and biodegradability which can be applied to various fields such as molded articles, films and fibers. An object of the present invention is to provide a method for producing a polymer with high productivity.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, when producing an aliphatic polyester copolymer, a specific trifunctional polyol was allowed to coexist in the reaction system. As a result, it has been found that the polymerization rate is greatly increased and an aliphatic polyester copolymer having improved biodegradability can be obtained. That is, the gist of the present invention is to produce an aliphatic polyester copolymer by reacting (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid or a derivative thereof, and (c) a bifunctional aliphatic oxycarboxylic acid. (D) A method for producing an aliphatic polyester copolymer having a number average molecular weight of 10,000 to 200,000, characterized by coexisting (d) a trifunctional polyol represented by the formula (I) in a reaction system.

[0008]

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[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

<(A) Aliphatic diol> The (a) aliphatic diol used in the present invention is an aliphatic compound having two hydroxyl groups and preferably represented by the following formula (III). It is.

HO-R ¹ -OH (III)

(Wherein R¹Is a divalent aliphatic hydrocarbon group,
Preferably it has 2 to 11 carbon atoms, particularly preferably 2 to 2 carbon atoms.
6 is a divalent aliphatic hydrocarbon group. Preferred R¹Is-
(CH _Two)_m-, And m is an integer of 2 to 11, preferably
Or an integer of 2 to 6) The aliphatic diol which can be used in the present invention is not particularly limited.
Although not specified, ethylene glycol
1,3-propanediol, 1,4-butanediol
1,1,5-pentanediol, 1,6-hexanediol
, 1,4-cyclohexanediol, 1,6-sic
Hexane dimethanol. These alone
They may be used or two or more of them may be used in combination. The resulting copolymer
In terms of physical properties, aliphatic diols are
Diol, ethylene glycol or 1,6-hexa
Particularly preferred is diol.

<(B) Aliphatic dicarboxylic acid or derivative thereof> The aliphatic dicarboxylic acid used in the present invention is not particularly limited as long as it has two carboxylic acid groups in the molecule. And (b) the aliphatic dicarboxylic acid is preferably represented by the following formula (IV).

[0012]

Embedded image HOOC-R ² —COOH (IV)

(Wherein R ² is a direct bond or a divalent aliphatic hydrocarbon group, preferably a divalent aliphatic hydrocarbon group having 2 to 11 carbon atoms, particularly preferably 2 to 6 carbon atoms) .
Preferred R ² is — (CH ₂ ) _p —. Where p
Is 0 or an integer of 1 to 11, preferably 0 or 1 to 6
Preferred specific examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid,
Suberic acid, dodecane diacid and the like can be mentioned. Derivatives generally include acid anhydrides and lower alkyl esters of aliphatic carboxylic acids, preferably acid anhydrides. From the physical properties of the obtained copolymer, the component (b) is preferably succinic acid or succinic anhydride. These dicarboxylic acids or derivatives may be used alone or in combination of two or more. <(C) Bifunctional aliphatic oxycarboxylic acid> The bifunctional aliphatic oxycarboxylic acid 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. Although not limited thereto, aliphatic oxycarboxylic acids of the following formula (V) are preferred.

[0014]

Embedded image HO—R ³ —COOH (V)

Wherein R ³ is a divalent aliphatic hydrocarbon group,
Preferably it has 1 to 11 carbon atoms, particularly preferably 1 to 1 carbon atoms.
6 is a divalent aliphatic hydrocarbon group. Those chain of these R ³ is preferably used. More preferably, a compound having a hydroxyl group and a carboxyl group at one carbon atom, particularly a compound of the formula (II)

[0016]

Embedded image

(Wherein, n is 0 or an integer of 1 or more, preferably 0 or 1 to 10, more preferably 0 or 1
To 5). Use of the bifunctional aliphatic oxycarboxylic acid (c) represented by the formula (II) increases the polymerization rate. Specific examples of the 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, Lactones such as hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, or caprolactone, or a mixture thereof, and the like are mentioned. When these have optical isomers, D
It may be in any of the form, L form, or racemic form, and may be in the form of a solid, liquid, or aqueous solution. In particular, lactic acid or glycolic acid, which is particularly remarkable in increasing the polymerization rate during use and is easily available, and aqueous solutions thereof are preferable. Lactic acid, glycolic acid, etc. are 50%, 70%
% And 90% aqueous solutions are generally commercially available and readily available. <(D) Trifunctional polyol> In the present invention, the following formula (I)
Are used.

[0018]

Embedded image

When the hydroxymethylhexanediol represented by the formula (I) is used in combination with the trifunctional polyol, an aliphatic polyester copolymer can be produced with a high polymerization rate and high productivity. Furthermore, when this hydroxymethylhexanediol is used in combination, the biodegradability, which is a characteristic of the aliphatic polyester, is also improved.

<Method for Producing Aliphatic Polyester Copolymer> The production of an aliphatic polyester copolymer is usually carried out by esterification followed by a glycol removal reaction. The esterification reaction may be performed at a temperature of 120 ° C. to 240 ° C., preferably 150 ° C. to 240 ° C., for a reaction time of 1 hour or more, preferably 1 to 10 hours, under an inert dry gas atmosphere at normal pressure. The subsequent deglycolization reaction was conducted at a temperature of 150 ° C
To 240 ° C., preferably 180 ° C. to 240 ° C., the reaction time is 1 hour or more, preferably 2 to 15 hours, the pressure is gradually reduced from normal pressure, and finally the pressure may be reduced to 10 mmHg or less, preferably 2 mmHg or less.

The amount of the aliphatic diol (a) used is substantially equimolar to the aliphatic dicarboxylic acid or its derivative (b), but in the actual production process, it is distilled during the esterification reaction. For this reason, it is usual to use 1 to 20 mol% in excess of 100 mol of the aliphatic dicarboxylic acid or its derivative (b).

The amount of the bifunctional aliphatic oxycarboxylic acid (c) used in the present invention is generally from 0.04 to 60 per 100 mol of the aliphatic dicarboxylic acid or its derivative (b).
Mol, preferably 1 to 20 mol, more preferably 3 to 1 mol.
0 mol. If the amount of the bifunctional aliphatic oxycarboxylic acid is too small, the effect of the present invention is hardly exhibited, and if the amount is too large, crystallinity is easily lost, which is not preferable in molding.

The timing of addition of the bifunctional aliphatic oxycarboxylic acid (c) is not particularly limited as long as it is before the polyester formation reaction. For example, (1) the catalyst is dissolved in the aliphatic oxycarboxylic acid solution in advance, A method in which the catalyst is added during the charging or during the esterification reaction, or (2) a method in which the catalyst is added simultaneously with the addition of the catalyst during the charging of the raw materials, is preferable.

The proportion of the trifunctional aliphatic polyol (d) used in the present invention is generally 0.01 to 5 per 100 mol of the aliphatic dicarboxylic acid or its derivative (b).
Is a mole. If the amount of the trifunctional aliphatic polyol (d) is less than 0.01 mol, the effect of the addition is hardly exhibited, and if it exceeds 5 mol, the risk of gelation during the reaction increases. A desirable use ratio is 0.1 to 1.0 mol. The timing of adding the trifunctional aliphatic polyol (d) is not particularly limited as long as it is before the polyester is formed, and it is convenient to add the trifunctional aliphatic polyol during the preparation of the raw material, but it may be added during the esterification reaction.

The process for producing an aliphatic polyester copolymer according to the present invention is generally carried out using the above-mentioned raw materials in the presence of a polymerization catalyst. As the catalyst, any catalyst that can be used for the production of the polyester copolymer can be selected, but germanium, titanium, antimony, tin, magnesium,
Metal compounds soluble in the reaction system such as calcium and zinc are exemplified. Among these, a germanium compound is preferable, and an organic germanium compound such as tetraalkoxygermanium, or an inorganic germanium compound such as germanium oxide and germanium chloride is particularly preferable. Due to price and availability, germanium oxide,
Particularly preferred is tetraethoxygermanium or tetrabutoxygermanium. The amount of these catalysts used is
It is generally 0.001 to 3% by weight, more preferably 0.005 to 1.5% by weight, based on the amount of monomer used, that is, the total amount of components (a) to (d). The timing of adding the catalyst is not particularly limited as long as it is before the production of the polyester, but may be added at the time of charging the raw materials, or may be added at the start of pressure reduction. It is particularly preferable to add the bifunctional aliphatic oxycarboxylic acid simultaneously with the bifunctional aliphatic oxycarboxylic acid or to dissolve the catalyst in the bifunctional aliphatic oxycarboxylic acid and an aqueous solution thereof when charging the raw materials.

The 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. , Preferably 180 to 2
30 ° C., the polymerization time is 1 hour or more, preferably 2 to 15 hours, and the degree of reduced pressure is 10 mmHg or less, more preferably 2 mm
It is preferable to select from the range of Hg or less.

<Aliphatic polyester copolymer> The aliphatic polyester copolymer produced by the production method of the present invention comprises the components (a) and (b) as main polyester members. When the raw materials are blended in the same blending ratio as described above, generally, the molar ratio of (a) the aliphatic diol unit and (b) the aliphatic dicarboxylic acid functional derivative unit becomes substantially equal, and the aliphatic polyester When the number of moles of all the constituent components of the copolymer is 100 mol%, (c) the bifunctional aliphatic oxycarboxylic acid unit is 0.1%.
02 to 30 mol%.

These have a structure branched or crosslinked by a part of the trifunctional aliphatic polyol unit. That is, a crosslinked structure and a branched structure are formed by the trifunctional aliphatic polyol unit. The (d) trifunctional aliphatic polyol unit is usually used in an amount of 0.01 to 100 mol per component (b).
It is used in a proportion of 5.0 mol, preferably 0.1 to 1.0 mol. Even if the trifunctional component (d) is copolymerized, the polyester copolymer of the present invention is fusible and belongs to the category of thermoplastic resin.

The present invention also relates to a process for producing an aliphatic polyester copolymer having a relatively large molecular weight. The number average molecular weight Mn is generally 10,000 to 200,000, usually 30,000 to 200,000. It is. 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.
Other copolymerization components include aromatic oxycarboxylic acids such as hydroxybenzoic acid, aromatic diols such as bisphenol A, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, or trifunctional or higher functional aromatic polyols, Group polycarboxylic acids, aromatic polycarboxylic acids, and tetra- or higher functional oxycarboxylic acids. These components are:
It is at most 50 mol%, especially at most 20 mol%. Further, the aliphatic polyester copolymer according to the production method of the present invention,
In practical use, lubricants, waxes, coloring agents, fillers, stabilizers and the like can be used in combination as necessary.

[0030]

The following examples serve to illustrate the present invention more specifically. The present invention is not limited to these examples unless it exceeds the gist. The number average molecular weight in the examples was measured by the following method. Number average molecular weight (Mn) Gel permeation chromatography (GP
It measured by the C) method. The sample was dissolved in chloroform, and measured in terms of polystyrene using a Tosoh HLC-8020 type GPC apparatus. Column is PLgel
-10μ-MIX was used.

Example 1 94.5 g of succinic acid and 79.3 of 1,4-butanediol were placed in a polymerization tube equipped with a stirring blade, nitrogen introduction and a pressure reducing port.
g, 90% in which germanium oxide was previously dissolved at 1% by weight.
4.8 g of an aqueous lactic acid solution and 0.12 g of hydroxymethylhexanediol (0.1 mol with respect to 100 mol of succinic acid) were charged and reacted in a nitrogen atmosphere at 180 ° C. for 0.5 hour, and then up to 220 ° C. in 1 hour. The temperature was raised, and the pressure was reduced to 0.5 mmHg over 1.5 hours. Followed by 0.5
The polymerization reaction was carried out for 4 hours under reduced pressure of mmHg. The obtained polyester is milky white, and Mn is 64000.
Met. The melt viscosity at 220 ° C. and a shear rate of 1000 sec ⁻¹ was 1200 poise. This polymer was hot-pressed at 220 ° C. to form a film having a thickness of 200 μm and buried in the soil. As a result, a weight loss of 32% was observed in three months.

Example 2 A reaction was carried out in the same manner as in Example 1 except that 0.36 g of hydroxymethylhexanediol (0.3 mol per 100 mol of succinic acid) was used and the polymerization time was 3 hours. The obtained polyester was milky white and Mn was 66,000. The melt viscosity at 220 ° C. and a shear rate of 1000 sec ⁻¹ was 1,300 poise. This polymer is 22
When a film having a thickness of 200 μm was formed by hot pressing at 0 ° C. and buried in the soil, a weight loss of 40% was recognized in three months.

Comparative Example 1 The reaction was carried out in the same manner as in Example 1, except that 0.32 g of trimethylolpropane (0.3 mol per 100 mol of succinic acid) was used instead of hydroxymethylhexanediol. The resulting polyester is milky white and has a M
n was 31,000. 220 ° C, shear rate 1000
The melt viscosity at sec ^-1 was 750 poise. This polymer was hot-pressed at 220 ° C. to form a film having a thickness of 200 μm and buried in the soil. As a result, only a 5% weight loss was observed in 3 months.

Comparative Example 2 The reaction was carried out in the same manner as in Example 1 except that hydroxymethylhexanediol was replaced by 0.22 g of glycerin (0.3 mol per 100 mol of succinic acid). The obtained polyester is milky white, and Mn is 29,000.
Met. The melt viscosity at 220 ° C. and a shear rate of 1000 sec ⁻¹ was 700 poise. This polymer is
When a film having a thickness of 200 μm was prepared by hot pressing at 20 ° C. and buried in soil, only a 5% weight loss was observed in 3 months.

COMPARATIVE EXAMPLE 3 94.5 g of succinic acid and 79.3 of 1,4-butanediol were placed in a polymerization tube equipped with a stirring blade, nitrogen introduction and a pressure reducing port.
g, 90% in which germanium oxide was previously dissolved at 1% by weight.
After 4.8 g of an aqueous lactic acid solution was charged and reacted at 180 ° C. for 0.5 hour in a nitrogen atmosphere, the temperature was raised to 220 ° C. in 1 hour, and the pressure was reduced to 0.5 mmHg over 1.5 hours.
Subsequently, a polymerization reaction was carried out for 4 hours under a reduced pressure of 0.5 mmHg. The resulting polyester is milky white,
Mn was 27000. 220 ° C, shear rate 100
The melt viscosity at ⁰ sec ^-1 was 600 poise.
This polymer is hot pressed at 220 ° C to a thickness of 200 μm.
When a film was prepared and buried in the soil, only 3% weight loss was observed in 3 months.

[0036]

According to the present invention, it is possible to produce a high-viscosity aliphatic polyester copolymer at a higher polymerization rate than that of the prior art, that is, with good productivity. The decomposition rate is also high. Since the aliphatic polyester copolymer obtained by the present invention has a high melt viscosity, it is advantageous for various moldings such as an injection molding method, a hollow molding method and an extrusion molding method.

Claims (9)

[Claims] 1. A reaction system for producing an aliphatic polyester copolymer by reacting (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid or a derivative thereof, and (c) a bifunctional aliphatic oxycarboxylic acid. A method for producing an aliphatic polyester copolymer having a number average molecular weight of 10,000 to 200,000, characterized by coexisting the following (d). (D) a trifunctional polyol represented by the formula (I): 2. In the presence of a catalyst, (a) an aliphatic diol,
(B) aliphatic dicarboxylic acid or a derivative thereof, (c) 2
A functional aliphatic oxycarboxylic acid and (d) a trifunctional polyol of the formula (I) The method according to claim 1, wherein 3. An aqueous solution of (c) a bifunctional aliphatic oxycarboxylic acid containing a catalyst is represented by (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid or a derivative thereof, and (d) a compound represented by the formula (I). Trifunctional polyol The method according to claim 2, wherein the mixture is added to a mixture of 4. The method according to claim 2, wherein the catalyst is a germanium compound. 5. An amount of (a) an aliphatic diol is 10 per 100 moles of (b) an aliphatic dicarboxylic acid or a derivative thereof.
0 to 120 mol, (c) 0.04 to 60 mol of the bifunctional aliphatic oxycarboxylic acid, and (d) trifunctional polyol represented by the formula (I). Is reacted at a ratio of 0.01 to 5.0 mol.
The method according to any one of claims 1 to 3. (C) the bifunctional aliphatic oxycarboxylic acid has the formula (II): The method according to claim 1, wherein n is 0 or an integer of 1 or more. 7. The method according to claim 1, wherein (c) the bifunctional aliphatic oxycarboxylic acid is lactic acid or glycolic acid. 8. The method according to claim 1, wherein (a) the aliphatic diol is 1,4-butanediol or ethylene glycol.
8. The method according to any one of items 7 to 7. 9. The method according to claim 1, wherein (b) the aliphatic dicarboxylic acid or a derivative thereof is succinic acid or succinic anhydride.
The method according to any one of claims 8 to 13.