JPH04292619A - Bio-degradable copolymerized polyester and bio-degradable resin composition - Google Patents

Abstract

PURPOSE:To provide a bio-degradable copolymerized polyester having excellent physical properties such as moldability as well as good bio-degradability and to provide a bio-degradable resin composition containing the above polyester as a main component. CONSTITUTION:The objective copolymerized polyester contains 5-95mol% of 3-hydroxyalkanoate and/or 4-hydroxyalkanoate and the remaining part of other recurring unit. The resin composition contains the copolymerized polyester as a main component.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable copolyester that decomposes well in the ecosystem and has excellent processability, and a biodegradable resin composition containing the copolyester as a main component.

0002

BACKGROUND OF THE INVENTION In recent years, due to social demands regarding environmental pollution, materials that decompose when left in an ecosystem, so-called biodegradable materials, have been widely studied.

[0003] As such biodegradable materials, polymeric materials are known that are made by mixing cornstarch with polypropylene, polyethylene, etc. for the purpose of collapsing the shape, but this only collapses in shape over time. , polypropylene, polyethylene, etc., because it does not involve decomposition of the polymer main chain, it cannot be said that it is a material that is biodegradable in an essential sense.

[0004] Biodegradable materials include poly(3-hydroxybutyrate) produced by certain microorganisms or chemically synthesized, copolymers containing it as a main component, and various polyhydroxyalkanoates. Are known. Poly(3-hydroxybutyrate) has been confirmed to decompose well when left in the natural environment, and also has excellent biocompatibility.
It was expected to be applied in a wide range of fields, including medical applications. However, since poly(3-hydroxybutyrate) is hard and brittle, it has physical property problems such as poor impact resistance, and although it has thermoplasticity, it begins to decompose even near its melting point. Therefore, it had poor workability and was not able to be used in a wide range of applications.

On the other hand, poly(3-hydroxybutyrate)
As an attempt to change the physical properties of
A copolymer having repeating units of D-(-)3-hydroxybutyrate and D-(-)3-hydroxyvalerate, which is disclosed in Japanese Patent No. 9 and the like, is known. Although this copolymer has good effects in terms of lower melting point and flexibility, it is expensive because it requires a special substrate in the fermentation synthesis process and has low productivity, so it cannot be used as a general-purpose material. has a problem. As described above, it is difficult to stably obtain a biodegradable resin having excellent physical properties and processability in large quantities through conventional fermentation synthesis of copolymers using culture.

Additionally, polymer blends of poly(3-hydroxybutyrate) and other resin materials, such as poly(3-hydroxybutyrate) and ethylene oxide (M
aruizio Avella and Ezio M
artuscelli, “poly-D(-)(3-
hydroxybutyrate)/poly(eth
ylene oxide) blends: phas
e diagram, thermal and cr
ystallization behavior",
POLYMER, 1988, Vol 29, O
ccover 1731-) (Marizio Abella
and Ezio Marzuchelli “Poly-D”
(-)(3-hydroxybutyrate)/poly(ethylene oxide) blend: fuse diagram, thermal and crystallization behavior,
Polymer October 1988 Volume 29 173
1 page-),

Polymer blends of poly(3-hydroxybutyrate) and ethylene-propylene rubber or polyvinyl acetate (Pietro Greco and E.
zio Martuscelli, “Crystal
lization and thermal beha
viour of poly(D(-)-3-hydr
oxybutyrate)-based blends
” POLYMER, 1989, Vol 30,
August 1475-) (Pietro Greco and Ezio Marzschelli "Crystalization and Thermal Behavior of Poly-D(-)(3-Hydroxybutyrate)-"
"Based Blends" Polymer 1989 8
Monthly Volume 30, Page 1475-),

Alternatively, modification by incorporation of sugars, such as incorporation of polysaccharides into hydroxybutyrate-hydroxyvalerate copolymers (M. Yasin, S.J.H.
olland, A. M. Jolly and B. J
．． Tighe, “Polymers for bio
degradable medical device
s: VI. Hydroxybutyrate-hy
droxyvalerate copolymers:
accelerated degradation
of blends with polysaccha
Biomaterials, 198
9, Vol10 August 400-) (M. Yashin, S.J. Holland, A.M. Jolly and B.J. Taie, “Polymers for Biodegradable Medical Devices: VI. Hydroxybutyrate-Hydroxyvalerate Copolymer "Accelerated degradation of brains with polysaccharization", Biomaterials, 198
(August 1999, Volume 10, Page 400) have been studied, but they have not yet achieved stable polymer composition, economic efficiency, or sufficient material improvement.

[0009]

[Problems to be Solved by the Invention] It is an object of the present invention to solve the problems of the prior art, and to provide a biodegradable copolymer that has good biodegradability and excellent physical properties such as processability. An object of the present invention is to provide a polymerized polyester and an inexpensive biodegradable resin composition containing the same as a main component.

In order to achieve the above object, the present invention provides that at least one of 3-hydroxyalkanoate and 4-hydroxyalkanoate is 5-hydroxyalkanoate in terms of repeating units.
Provided is a biodegradable copolyester characterized in that it contains ~95 mol% of the copolyester, with the remainder having different repeating units.

[0011] The 3-hydroxyalkanoate is one or more selected from the group consisting of 3-hydroxypropionate, 3-hydroxybutyrate, 3-hydroxyvalerate and 3-hydroxyoctanoate. is preferred.

[0012] Furthermore, it is preferable that the 4-hydroxyalkanoate is at least one of 4-hydroxybutyrate and 4-hydroxyvalerate.

[0013] Further, the constituent repeating units other than 3-hydroxyalkanoate and 4-hydroxyalkanoate of the copolymerized polyester are ethylene adipate,
Preferably, it is at least one of ethylene azelate, ethylene sebacate, tetramethylene adipate, tetramethylene sebacate, hexamethylene sebacate, ε-caprolactone and β-propiolactone.

Another aspect of the present invention provides a biodegradable resin composition comprising the biodegradable copolyester as a main component.

The biodegradable copolyester and biodegradable resin composition of the present invention will be explained in detail below. As is well known, polyesters (so-called polyhydroxyalkanoates) produced by microorganisms, typified by poly(3-hydroxybutyrate), are attracting attention for various uses as fully biodegradable resins. However,
The homopolymer poly(3-hydroxybutyrate) that makes up many of these materials is hard and brittle, so
In order to improve this, various modifications have been attempted, such as fermentation synthesis of the copolymer and blending it with other polymers, but as mentioned above, the desired effect has not been achieved. .

The biodegradable copolyester of the present invention is
It is a copolymerized polyester containing 5 to 95 mol% of 3-hydroxyalkanoate and 4-hydroxyalkanoate (hereinafter also referred to as alkanoate) in terms of repeating units, with the remainder having different repeating units. Therefore, the part of the polymer or oligomer formed of alkanoate is completely decomposed by microorganisms or components secreted by microorganisms, so that good biodegradability can be exhibited. Furthermore, although the decomposition rate of the remaining portion is considerably lower than that of the alkanoate, it can be decomposed by an ester hydrolase such as lipase or by simple hydrolysis. Moreover, since the copolymerized polyester of the present invention is a copolymer, its melting point is lower than that of a homopolymer.
It can exhibit good heat workability.

Preferably, the constituent repeating units other than the alkanoate component are ethylene adipate, ethylene azelate, ethylene sebacate, tetramethylene adipate, tetramethylene sebacate, hexamethylene sebacate, ε-caprolactone, and β-propioate. By constituting the copolymer polyester as a lactone, this part also has biodegradability and can exhibit better biodegradability.

The biodegradable copolymerized polyester of the present invention (hereinafter referred to as copolymerized polyester) basically contains at least one of 3-hydroxyalkanoate and 4-hydroxyalkanoate in an amount of 5 to 50% in terms of repeating units.
It is a copolymerized polyester containing 95 mol%. Here, as the 3-hydroxyalkanoate serving as a repeating unit, known ones preferably having about 3 to 8 carbon atoms can be used, but specifically, 3-hydroxypropionate, 3-hydroxy Butyrate, 3-hydroxyvalyrate, and 3-hydroxyoctanoate are particularly preferably applied.

On the other hand, as the 4-hydroxyalkanoate, known ones preferably having about 3 to 8 carbon atoms can be used, but specifically 4-hydroxybutyrate and 4-hydroxyvalerate are particularly suitable. A suitable example is given. Among them, 3-hydroxybutyrate is particularly preferably applied.

[0020] In the copolymerized polyester of the present invention, the alkanoate component may be a copolymer. Specifically, (3-hydroxybutyrate)-(3-hydroxypropionate) copolymer, (3-hydroxybutyrate)-(3-hydroxypropionate)-(4-
hydroxybutyrate) copolymer, (3-hydroxybutyrate)-(3-hydroxyvalerate) copolymer, (3-hydroxybutyrate)-(3-hydroxyvalerate)-(4-hydroxybutyrate) copolymer, (3-hydroxybutyrate)-(3-hydroxyvalerate)-(4-hydroxybutyrate) copolymer, -hydroxybutyrate)-(3-hydroxyvalerate)-(3-hydroxyhexanoate)-(
3-hydroxyheptanoate)-(3-hydroxyoctanoate) copolymer, (3-hydroxybutyrate)-(3-hydroxyhexanoate)-(3-hydroxyoctanoate) copolymer, (3-hydroxybutyrate)-(3-hydroxyhexanoate)-(3-hydroxyoctanoate) copolymer, Suitable examples include (3-hydroxybutyrate)-(4-hydroxybutyrate) copolymer and (3-hydroxybutyrate)-(4-hydroxyvalerate) copolymer.

[0021] Methods for synthesizing polymers or oligomers containing these alkanoates as repeating units include:
Various methods are exemplified, such as a method in which microorganisms that produce these are fermented and synthesized, and a method using chemical synthesis.

Examples of microorganisms that produce polyhydroxyalkanoates include Acinetobacter [Acinetobacter].
tobacter], Actinomycetus
[Actinomycetes], Alcaligenes, Aph
anothece], aquaspirillum [Aquas
pirilum], Azospirillum [Azospi
rillum], Azotobacter [Azotobacter]
er], Bacillus, Beggiatoa, Beij
erinckia], Caulobacter [Caulobacter]
cter], Chlorofrex [Chlorofrex]
eus], Chlorogloea [Chlorogloea]
], Chromatium, Chromobacterium
, Clostridium ,
Derxia, Ectothiorhodospira, Echerichia, Ferobacillus [F
errobacillus], Gamphosphaeria, Haemophilus [H
aemophilus], Halobacterium [Hal
obacterium], Hyphomicrobium [H
yphomicrobium], lamprocytis [
Lamprocystis], Lampropedia [La
mpropedia], Leptothrix [Lept
othrix], Methylobacterium [Methylo
bacterium], Methylocystis [Meth
ylocystis], Micrococcus [Micro
coccus], Microcoleas [Microcol]
eus], Microcystis [Microcyst
is], Moraxella, Mycoplana, Nitrobacter [
Nitrobacter], Nitrococcus [Nit
rococcus], Nocardia [Nocardia
], Oceanospirillum [Oceanospirillum]
um], Paracoccus, Photobacterium,
Pseudomonas, Rhizobium, Rho
dobacter], Rhodospirillum [Rhodos
pirilum], Sphaerochilus [Sphaero
tilus], Spirillum,
Spirulina, Streptomyces, Syntrophomonas, Thiobalasis
Thiobacillus], Thiobacillus [Thioc
apsa], Thiocystis [Thiocysti
s], Thiodiction [Thiodiction]
, Thiopedia, Thiosphaera, Vibrio
rio], Santobacter [Xanthobacter]
], Zoogloea, and other bacterial species are exemplified.

[0023] As a method of fermenting and synthesizing these polymers or oligomers using microorganisms, the hydrogen bacterium Alcaligenes eutrophus [Alcaligenes
eutrophus] H16ATCC17699 is cultured at 30°C for about 2 days in a pH 7.5 phosphate buffer medium containing only fructose and minerals, and the poly(3-hydroxybutyrate) that accumulates inside the bacterial cells is Method of extraction with chloroform;

(3-hydroxybutyrate)-(3-
Method for obtaining hydroxyvalerate) copolymer;

002
5. Similarly, a method for obtaining a (3-hydroxybutyrate)-(4-hydroxybutyrate) copolymer by adding γ-butyrolactone instead of fructose is exemplified.

[0026] Furthermore, various polypolymers can be produced by polycondensation reactions and ring-opening polymerization reactions of 3-hydroxybutyric acid, 3-hydroxybutyric acid chloride, 4-hydroxyvaleric acid, β-butyrolactone, γ-butyrolactone, β-valerolactone, etc. (
3-hydroxyalkanoate), poly(4-hydroxyalkanoate), or a copolymer thereof.

[0027] In the present invention, Aldrich
Various polyhydroxyalkanoates commercially available from Co., Ltd., Polysciences Co., Ltd., etc. may be used.

The polyester constituting the main component of the copolymerized polyester of the present invention contains 5 to 95 mol % of such alkanoate in terms of repeating units. If the content of alkanoate is less than 5 mol%, good biodegradability cannot be exhibited, and if the content exceeds 95 mol%, it may be unfavorable in terms of processability, thermal stability, etc.

The copolyester of the present invention is a copolyester containing such an alkanoate. Here, as the repeating monomer unit other than the alkanoate constituting the copolymerized polyester, various types of monomer units that can be copolymerized with the alkanoate to form a polyester can be used.

Preferably, polymers, oligomers, dimers, monomers that are condensates of ethylene glycol and adipic acid or adipic acid derivatives (hereinafter collectively referred to as ethylene adipate), ethylene glycol and azelaic acid or azelaic acid derivatives Polymers, oligomers, dimers, and monomers that are condensates with (hereinafter collectively referred to as ethylene azelate)
, polymers, oligomers, dimers, monomers that are condensates of ethylene glycol and sebacic acid or sebacic acid derivatives (hereinafter collectively referred to as ethylene sebacate), condensation products of tetramethylene glycol and adipic acid or adipic acid derivatives polymers,
Oligomers, dimers, monomers (hereinafter collectively referred to as tetramethylene adipate), polymers that are condensates of tetramethylene glycol and sebacic acid or sebacic acid derivatives, oligomers, dimers, monomers (hereinafter collectively referred to as tetramethylene adipate) tetramethylene sebacate), polymers, oligomers, dimers, and monomers that are condensates of hexamethylene glycol and sebacic acid or sebacic acid derivatives (hereinafter collectively referred to as hexamethylene sebacate), and ε-caprolactone. Polymers, oligomers, dimers, and monomers that are ring polymers (hereinafter collectively referred to as ε-caprolactone); polymers, oligomers, dimers, and monomers that are ring-opening polymers of β-propiolactone (hereinafter, collectively referred to as ε-caprolactone)
Various examples include biodegradable materials such as β-propiolactone (collectively referred to as β-propiolactone).

Among others, ethylene adipate and ε
- at least one of caprolactone is preferred.

[0032] By composing the components other than the alkanoate of the copolymerized polyester with the above-mentioned biodegradable substances, better biodegradability can be exhibited.

Polymers and oligomers such as ethylene adipate and ε-caprolactone can be synthesized by various known methods. For example, ethylene adipate can be synthesized by combining ethylene glycol and adipic acid or adipic acid chloride with triethylamine, propylene oxide, etc. A method of polycondensation in the presence of is exemplified. On the other hand, an example of a polymer or oligomer of ε-caprolactone is a method in which ε-caprolactone is subjected to ring-opening polymerization under an ionic polymerization catalyst.

[0034] These polymers and oligomers are
Those commercially available from Aldrich and others may be used.

[0035] Furthermore, it is known that these polymers are decomposed, albeit slowly, by various lipases which are ester decomposing enzymes. For example, Y. Tokiwa,
T. Suzuki and K. Takeda,
"Hydrolysis of Polyesters"
by Rhizopus arrhizus Lip
ase”, Agric. Biol. Chem. ,5
0(5), 1323-1325 (1986) (Wai Tokiwa, T. Suzuki & K.
Takeda, “Hydrolysis of Polyesters”
By Rhizopus Alhizas Lipase”, Agric. Biol. Chem. 1986 50(5)
, pages 1323-1325)

[0036] There is no particular limitation on the method of copolymerizing the above-mentioned alkanoate with ethylene adipate, ε-caprolactone, etc. to obtain the copolymerized polyester of the present invention, and various known methods can be applied. .

One example is a method in which an alkanoate polymer as a raw material is transesterified with polyethylene adipate or the like under an ionic polymerization catalyst. In addition, monomers that serve as repeating units of alkanoates such as 3-hydroxybutyric acid and 4-hydroxybutyric acid, and monomers that serve as other repeating units such as ethylene adipate and ε-caprolactone are charged into one reaction system, and under the ionic polymerization catalyst, It can also be obtained by reacting with

However, no matter which method is used for the reaction, the content of alkanoate in the resulting copolymerized polyester is 5% in terms of repeating units.
It is necessary to adjust the amount of each raw material charged so that the amount becomes ~95 mol%.

The ionic polymerization catalyst to be applied is not particularly limited, and various known catalysts such as various acids, metal alkoxides, and acylated metals can be used. Specifically, boron trifluoride , boron trifluoride diethyl ether (F3 BOEt2 ), aluminum trichloride, aluminum triisopropoxide, diacetyl zinc, and the like.

[0040] The number average molecular weight of the copolymerized polyester thus synthesized is usually 5,000 to 1,000.
000,000 or so, preferably 8,000 to 2
It is about 50,000.

The copolymerized polyester of the present invention can be used as a compatibilizer for substances that are incompatible with the hydroxyalkanoate such as poly(3-hydroxybutyrate) and the ε-caprolactone or ethylene adipate. is also suitably applicable. In this case, a sufficient effect can be obtained when the content of the copolyester as a compatibilizer is 10 wt% or less of the total resin amount. Moreover, by making both of them compatible, effects such as improved mechanical properties and lowered glass transition temperature (Tg) can be obtained.

A biodegradable resin composition according to another embodiment of the present invention is one containing the copolymerized polyester of the present invention as a main component, and contains various resins, fillers, dyes, and pigments in addition to the copolymerized polyester. , a lubricant, an antioxidant, a stabilizer, etc. What is contained in addition to the copolymerized polyester may be appropriately determined according to the intended use of the biodegradable resin composition, and is not particularly limited. Incidentally, the term "the copolymerized polyester is the main component" means that the amount of the copolymerized polyester in the composition is at least 20 wt% or more, preferably 50 wt% or more.

Although the biodegradable copolyester and biodegradable resin composition of the present invention have been described in detail above, the present invention is not limited thereto, and various modifications may be made without departing from the gist of the present invention. Of course, improvements and changes may be made.

[0044]

[Examples] Hereinafter, the present invention will be explained in more detail with reference to specific examples.

[Synthesis Example 1] Polypeptone (manufactured by Nippon Pharmaceutical Co., Ltd.) was added to 100 ml of poly(3-hydroxybutyrate) synthetic water.
1g, yeast extract (DIFCO) 1g, meat extract (
5 g of a liquid medium containing 0.5 g (manufactured by Kyokuto Pharmaceutical Co., Ltd.) and 0.5 g of ammonium sulfate (manufactured by Wako Pure Chemical Industries, Ltd.).
Place the hydrogen bacterium Alcaligenes eutrophus in a 00ml Sakaguchi flask.
[trophus] H16 ATCC 17699
was inoculated and cultured by shaking at 30°C for 48 hours to sufficiently increase the number of bacteria. Put together 10 of these,
Centrifugation was performed at 6000 rpm for 15 minutes to collect the grown bacteria.

On the other hand, 20 wt/V% sulfuric acid was added to a pH 7.5 phosphate buffer containing 14.0 ml of 0.5 M potassium dihydrogen phosphate and 124.0 ml of 0.25 M disodium monohydrogen phosphate in 1 liter. A medium was prepared by adding 1.0 ml of magnesium, 1.0 ml of the mineral solution shown in Table 1 below, and 20 g of fructose (manufactured by Kanto Kagaku Co., Ltd.).

[0047]

[0048] This medium was placed in a 2.6-liter jar fermenter (manufactured by Marubishi Bio-Engineering Co., Ltd.), and the previously collected bacterial cells were transferred thereto, and the mixture was heated at 30°C and stirring blade rotation speed at 500 rpm.
The cells were cultured for 48 hours at an aeration rate of 1 ml/min. After the culture was completed, the cells were collected by centrifugation at 6000 rpm for 15 minutes, washed with water, and then freeze-dried.

11.2 g of the dried bacterial cells obtained were placed in 2 liters of chloroform and stirred at room temperature for 24 hours to extract the polymer. After filtering the extract to remove unnecessary bacterial components,
The polymer was precipitated by dropping it into about 10 times the amount of n-hexane (grade 1 reagent manufactured by Wako Pure Chemical Industries, Ltd.).

The polymer thus obtained was thoroughly washed with n-hexane, recovered, and dried under vacuum.
7 g of poly(3-hydroxybutyrate) was obtained. Identification was performed using a nuclear magnetic resonance spectrometer (EX-9 manufactured by JEOL Ltd.) using deuterium-substituted chloroform as a solvent.
0) by measuring the 1H-NMR spectrum in Fourier transform mode.

The number average molecular weight of the obtained poly(3-hydroxybutyrate) was measured by gel chromatography (Shimadzu LC-6A manufactured by Shimadzu Corporation) and Shodex GPC-80M manufactured by Showa Denko Co., Ltd.
The result was 780,000. In addition, a differential thermal analyzer (manufactured by Shimadzu Corporation)
DSC-50 Under N2 atmosphere Temperature increase 10℃/min
), the melting point was 179°C.

[Synthesis Example 2] The same procedure as above except that 20 g of valeric acid (special grade, manufactured by Tokyo Chemical Industry Co., Ltd.) was added instead of fructose to the synthetic medium of (3-hydroxybutyrate)-(3-hydroxyvalerate) copolymer. In the same manner as in Synthesis Example 1, 4.0 g of (3-hydroxybutyrate)-(3-hydroxyvalerate) copolymer was obtained.

When the 1H-NMR spectrum was measured in the Fourier transform mode in the same manner as in Synthesis Example 1, it was found that the (3-hydroxybutyrate)-(3-hydroxyvalerate) copolymer contained 37 mol% of 3-hydroxybutyrate. It was confirmed that it was a combination. Further, when the number average molecular weight was measured in the same manner as in Synthesis Example 1, it was found to be 230,000.

[Invention Example 1] 0.20 g of poly(3-hydroxybutyrate) obtained in Synthesis Example 1 and poly(ε
-caprolactone) (manufactured by Aldrich, number average molecular weight 27,000) and 0.002 g of diacetyl zinc (special grade, manufactured by Kanto Kagaku Co., Ltd.) were placed in a pressure tube, and approximately 10 ml of chloroform was added to dissolve and mix. Next, the pressure of this system was reduced to distill off chloroform, and nitrogen gas was further introduced to replace the inside of the system with a nitrogen atmosphere. Further, nitrogen replacement by degassing and introducing nitrogen was repeated five times to create a complete nitrogen atmosphere in the system, and the pressure tube was closed. This pressure tube was immersed in a 180° C. oil bath and reacted for 3 hours.

After cooling, the obtained reaction product was dissolved in about 10 ml of chloroform, insoluble materials were filtered off, and the filtrate was mixed with about 10 times the volume of methanol (grade 1, manufactured by Wako Pure Chemical Industries, Ltd.).
The polymer was collected by filtration, thoroughly washed with methanol, and then dried under vacuum to obtain 0.31 g of polymer.

This polymer was fractionated into hot acetone using a Soxhlet extractor, and 0.14 g of pale yellow powder polymer was obtained from the acetone-soluble portion, and 0.15 g of white powder polymer was obtained from the acetone-insoluble portion.

The 1H-NMR spectrum was measured in the same manner as before, and the proton signal intensity derived from oxygen-adjacent methylene in poly(ε-caprolactone) and the proton signal intensity derived from methine in poly(3-hydroxybutyrate) were compared. As a result, the acetone soluble part was 91 mol%, while
The acetone-insoluble portion was confirmed to be a copolymer of ε-caprolactone and 3-hydroxybutyrate, each containing 5 mol% of ε-caprolactone component. Further, as a result of measuring the number average molecular weight in the same manner as above, the acetone soluble portion was 17,000 and the acetone insoluble portion was 14,000.

The copolymer thus obtained was dissolved in chloroform and cast onto a glass petri dish, and the chloroform was distilled off to form a film. A 1×1 cm test piece (weighing about 8 mg) was cut out from this film, and a biodegradation experiment was conducted as follows.

[0059] Alcaligenes faecali
The test piece was immersed for 19 hours in 1 ml of phosphate buffer (pH 7.4) at 37°C in which 8 μg of poly(3-hydroxybutyrate) degrading enzyme released by T1 outside the bacterial cells was dissolved. As a result, the weight difference before and after the experiment was 0.17 mg for the acetone-soluble part of the test piece and 3.19 m for the acetone-insoluble part.
It was g. This weight difference is thought to be due to the decomposition of the test piece (film) to produce water-soluble components, and it was confirmed that the copolymer was biodegradable. The above results are summarized in Table 2 below.

[0060] Furthermore, the Al used in the above biodegradability experiment
caligenes faecalis T1 was isolated from activated sludge, but there are countless microorganisms that release poly(3-hydroxybutyrate)-degrading enzymes outside of their cells, and they can be found in ordinary soil, seawater, lake water, It is thought to be present in rivers and activated sludge. Therefore, it is thought that a polymer that exhibits biodegradability by the method shown in this specification will decompose even in a normal natural environment (ecosystem).

[Invention Example 2] Poly(ε-caprolactone)
A copolymer was prepared in the same manner as in Example 1, except that the number-average molecular weight of part showed biodegradability. The results are summarized in Table 2.

[Invention Example 3] Poly(ε-caprolactone)
A copolymer was prepared in the same manner as in Example 1, except that ε-caprolactone monomer was used instead of ε-caprolactone monomer and the reaction time was 20 minutes, and the same experiment was conducted. The acetone-soluble portion of this product also showed biodegradability. The results are shown in Table 2.

[Invention Example 4] The reaction catalyst was changed from diacetyl zinc to boron trifluoride diethyl ether (Aldrich
A copolymer was prepared in the same manner as in Example 1 above, except that the amount was changed to 2 mg (manufactured by Co., Ltd.) and the reaction time was 1 hour, and the same experiment was conducted. The acetone-soluble portion of this product also showed biodegradability. The results are shown in Table 2.

[Invention Example 5] Using 0.2 g of the (3-hydroxybutyrate)-(3-hydroxyvalerate) copolymer synthesized in Synthesis Example 2 instead of poly(3-hydroxybutyrate), Reaction temperature: 170℃, reaction temperature: 3
A copolymer was produced in the same manner as in Example 1. When similar biodegradation experiments were conducted, the acetone-soluble portion showed biodegradability. The results are shown in Table 2.

[Comparative Example 1] Poly(ε-caprolactone)
(Manufactured by Aldrich, number average molecular weight 27,000
) was hot press molded at a press temperature of 70°C to obtain the above Example 1.
A similar sample was prepared and a biodegradation experiment similar to that in Example 1 was conducted. However, no difference in weight was observed before and after the experiment, indicating no biodegradability in this system. Table 2 shows the results.
Shown below.

[Comparative Example 2] The same reaction as in Example 1 was carried out except that no catalyst such as diacetylzinc was used. All of the obtained polymers were soluble in acetone. Furthermore, when similar biodegradation experiments were conducted, no biodegradability was observed. The results are shown in Table 2.

[0067] In Table 1 above, ε-CL indicates ε-caprolactone.

From the above examples, it can be seen that the product of the present invention has good biodegradability. In addition, the product of the present invention has a melting point of 167
℃ or less and the melting point of poly(3-hydroxybutyrate) 17
Since the temperature is lower than 9° C. and the decomposition temperature of 185° C., the molding temperature can be lowered, and the possibility of decomposition, deterioration, etc. occurring during hot molding is extremely low.

[Invention Example 1] For 100 parts by weight of the polymer prepared in Invention Example 4, 20 parts by weight of talc (JA-80R, manufactured by Asada Seifun Co., Ltd.) and an antioxidant (Irganox 1010, manufactured by Ciba Geigy) were added. 0.5 parts by weight,
One part by weight of titanium oxide (Tiepeke, manufactured by Ishihara Sangyo Co., Ltd.) was mixed on a mixing roll heated to 165°C, taken out in a sheet form, and then cut with a sheet pelletizer to form pellets. This was molded into a tube shape with an outer diameter of 10 mm and an inner diameter of 5 mm using an extrusion molding machine (Plastomill manufactured by Toyo Seiki Seisakusho Co., Ltd.) at a nozzle and die temperature of 170°C. This was a hard tube. The tube was cut into pieces about 2 cm long and buried in the soil in Nakai Town, Ashigarakami District, Kanagawa Prefecture. When they dug it up six months later, they were unable to find any fragments as it had completely decomposed.

From the above results, the effects of the present invention are clear.

[0071]

Effects of the Invention As explained in detail above, the biodegradable copolyester and biodegradable resin composition of the present invention not only have good biodegradability but also excellent physical properties such as processability.
Moreover, it has the excellent property of being inexpensive. The biodegradable copolyester and biodegradable resin composition of the present invention are widely used as materials for various packaging materials, medical devices such as catheters and blood bags, molding materials, etc. as materials that are free from environmental pollution. It is applicable to the following uses.

Claims (5)

[Claims] 1. A copolymerized polyester containing 5 to 95 mol% of at least one of 3-hydroxyalkanoate and 4-hydroxyalkanoate in terms of repeating units, and the remainder having different repeating units. Biodegradable copolyester. 2. The 3-hydroxyalkanoate is 3-hydroxyalkanoate.
The biodegradable copolyester according to claim 1, which is one or more selected from the group consisting of -hydroxypropionate, 3-hydroxybutyrate, 3-hydroxyvalerate, and 3-hydroxyoctanoate. 3. The 4-hydroxyalkanoate is 4-hydroxyalkanoate.
The biodegradable copolyester according to claim 1 or 2, which is at least one of -hydroxybutyrate and 4-hydroxyvalerate. 4. The constituent repeating units other than 3-hydroxyalkanoate and 4-hydroxyalkanoate of the copolymerized polyester are ethylene adipate, ethylene azelate, ethylene sebacate, tetramethylene adipate, tetramethylene sebacate, hexamethylene. The biodegradable copolyester according to any one of claims 1 to 3, which is at least one of sebacate, ε-caprolactone, and β-propiolactone. 5. A biodegradable resin composition comprising the biodegradable copolyester according to any one of claims 1 to 4 as a main component.