JPH08217865A - Biodegradable copolyester and its production - Google Patents

Abstract

PURPOSE: To obtain a biodegradable copolyester represented by a specified formula which is inexpensive and highly biodegradable by reacting an alkylene terephthalate arom. polyester with a hydroxyalkanoate aliph. polyester.

CONSTITUTION: An arom. polyester having an alkylene terephthalate structure as a repeating unit (pref. polyethylene terephthalate or polybutylene terephthalate with an no. average mol.wt. of not less than 10,000) is reacted with an aliph. polyester having a hydroxyalkanoate structure as a repeating unit [pref. poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) which has been biosynthesized by microbial fermentation] in the presence of a solvent and a catalyst at 100°C or above to obtain the contemplated polyester represented by formula [wherein n is not more than 10; R represents CH₃ or C₂H₅; and X represents -CH₂C(CH₃) H-, -CH₂C(C₂H₅)H- or -(CH₂)₃-].

COPYRIGHT: (C)1996,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copolyester having excellent biodegradability and a method for economically producing a biodegradable copolyester, and more particularly to a known aromatic compound having a number average molecular weight of 5,000 or more. The present invention relates to a biodegradable copolymerized polyester obtained by copolymerizing a polyester and an aliphatic polyester biosynthesized by microbial fermentation, and a method for producing the same.

[0002]

2. Description of the Related Art Polyester, especially polyethylene terephthalate, is used in daily life as a substitute for natural fiber because of its excellent mechanical properties, chemical resistance and durability. Have disadvantages that are not.

In recent years, single-use or disposable packaging materials, whose demand has been rapidly increasing, are often not recovered smoothly despite many consumptions and are left as they are, and it is difficult to completely recover agricultural films. Emerged as a social issue,
Along with this, development of degradable resins that are automatically degraded when disposed after being used for a certain period of time in the environment protection dimension has been actively developed. Degradable resins are classified into biodegradable resins that are decomposed by microorganisms present in soil and photodegradable resins that are decomposed by ultraviolet rays of sunlight.

[0004]

However, the photodegradable resins developed so far have a disadvantage that when the film is buried in soil, it is not decomposed without receiving light. Examples of the biodegradable resin include polyhydroxyallylate resin synthesized in vivo by microorganisms and polycaprolactone, which is a synthetic polymer biodegradable resin. Such a resin has excellent degradability, but its production cost is low. It is expensive, has poor economics, and has weak application properties.

Therefore, an object of the present invention is to provide a copolyester having a low manufacturing unit price and excellent biodegradability, and another object of the present invention is to manufacture the biodegradable copolyester for the above purpose. To provide a way to do.

[0006]

In order to achieve not only the above objects but also other objects which are obvious, in the present invention, an aromatic polyester having a number average molecular weight of at least 5,000 or more was biosynthesized by microbial fermentation. By producing a copolyester by reacting an aliphatic polyester in the presence of a solvent and a catalyst, a copolyester having excellent biodegradability can be produced at low cost.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is described below in detail.

An aromatic polyester and an aliphatic polyester biosynthesized by microbial fermentation are stirred and reacted in a reaction tube at a temperature of 100 ° C. or more while maintaining a nitrogen atmosphere in the presence of a solvent and a catalyst. A copolyester represented by the formula (I) is produced.

[0009]

Embedded image Here, n is an integer of 10 or less,

[Chemical 6] a, b and c are integers of 1 or more.

That is, the biodegradable copolyester produced in the present invention has a structure in which an alkylene terephthalate as a repeating unit and a structure having a hydroxyalkanoate as a repeating unit are bonded.

The aromatic polyester used in the present invention is obtained by esterifying or transesterifying an aromatic compound having at least two or more carboxylic acid groups or a lower alkyl ester compound thereof with a polyhydric alcohol as a polymerization component. It can be produced by a polycondensation reaction under vacuum. Preferred aromatic compounds include dicarboxylic acid components such as terephthalic acid, isophthalic acid and 1,4-cyclohexanedicarboxylic acid, and acid ester compounds such as dimethyl terephthalate, dibutyl terephthalate, dimethyl isophthalate and dibutyl isophthalate. .
3, such as 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, trimellitic anhydride
If the functional acid component is used as a copolymerization component, the above-mentioned 2
It may be used in a small amount together with the functional acid compound or its lower alkyl ester.

Examples of the polyhydric alcohol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and 1,4. -Cyclohexanedimethanol and the like can be used, and those obtained by copolymerizing a small amount of trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, tris (2-hydroxyethyl) isocyanurate and the like with a bifunctional glycol component can also be used.

It is preferable that the aromatic polyester synthesized by the combination of the above-mentioned polymerization components has a number average molecular weight of at least 5,000 in order to improve the mechanical properties of the resulting copolyester. More preferably, it is effective to use a polymer having a number average molecular weight of 10,000 or more. When the number average molecular weight is 5000 or less, there is a problem that mechanical properties such as tensile strength and elongation are reduced.

In the present invention, the aliphatic polyester synthesized by microbial fermentation includes poly (3-hydroxybutyrate) and poly (3-hydroxybutyrate-co-3).
-Hydroxyvalerate), poly (4-hydroxybutyrate), poly (3-hydroxybutyrate-co-4-)
Hydroxybutyrate) and the like.

In the present invention, nitrobenzene and dimethyl sulfoxide are used as the solvent.
Ifoxide) or the like can be used. As a catalyst, dibutyltin oxide (dibutyltin oxide) is used.
xide), tin chloride (Tin [IV] chlor
ide), Chin octoate (Tin [IV] octoa
te), hexabutyl distannoxane (Hexabut
yl distannoxane, tributyltin methoxide
e), tributyltin chloride (Tributyltin chloride)
n chloride, etc. are suitable for use due to their excellent catalytic activity.

The following examples illustrate the invention more specifically and do not limit the scope of the invention.

In the examples, the biodegradability is measured by AST
MG21-70 and decomposable accelerated parity method (Compos
Ting method). That is, a sample film is placed on an agar solid medium, and Aspergillus niger is placed thereon.
r), penicillinium funiculosum (Penici)
llium funiculosum, Trichoderma SP and Pullularia pullulans
a certain amount of a mixed spore solution of ulans) is dispersed, and after 2 to 4 weeks, the degree of growth of mold is confirmed. If the area of the sample piece is 10% or less, 1; 60%
If it is 60% or more, it is shown as 3.

On the other hand, the measuring process of the degradability acceleration evaluation method is as follows. As a medium, the composition is as shown in Table 1 so as to correspond to the composition ratio of the refuse generated in Korea, the internal environment is adjusted as shown in Table 2, and the sample film is inserted.
After maintaining for a week, the degree of degradation was evaluated by measuring the weight loss of the sample film.

[0019]

[Table 1]

[Table 2] Example 1 5 parts by weight of polyethylene terephthalate having a number average molecular weight of 15000 and 5 parts by weight of poly (3-hydroxybutyrate) having a number average molecular weight of 37000 in a reactor equipped with a stirrer, a condenser, a gas inlet tube and a thermometer. Parts, 89.9 parts by weight of nitrobenzene as a solvent, and 0.1 part by weight of dibutyltin oxide as a catalyst, and the mixture was heated at a temperature of 170 ° C. and reacted under a nitrogen atmosphere for 24 hours. Then
The reaction product was precipitated in excess methanol, and the precipitate was filtered, dissolved in a mixed solvent of orthochlorophenol / chloroform, and reprecipitated with excess methanol to obtain a copolymerized polyester. Table 3 shows the results of analyzing the physical properties of the produced polyester.

The formation of the copolyester was confirmed by infrared spectroscopy and nuclear magnetic resonance analysis. That is, as shown in FIG. 1, when the copolymerization reaction product of polyethylene terephthalate and poly (3-hydroxybutyrate) is analyzed by infrared spectroscopy, the characteristic peaks of polyethylene terephthalate are 727 cm ⁻¹ , 1017 cm ⁻¹ and 1341 cm ^−1.
Since the peak and characteristic peaks of poly (3-hydroxybutyrate) of 1058 cm ^-1 and 1174 cm ^-1 all appear, the copolyester of Example 1 has a coexisting structure of polyethylene terephthalate and poly (3-hydroxybutyrate). It was found to have According to ¹ H-nuclear magnetic resonance analysis, polyethylene terephthalate-
In addition to the 4.93 ppm peak corresponding to hydrogen of OCH _{2 and} the 5.51 ppm peak corresponding to hydrogen of poly (3-hydroxybutyrate) -OCH, hydrogen at the bonding portion of polyethylene terephthalate and poly (3-hydroxybutyrate) Corresponding to 4.70ppm, 4.78ppm,
A new peak appeared at 5.75 ppm, and according to ¹³ C-nuclear magnetic resonance analysis, -OCH of polyethylene terephthalate was obtained.
66.3 ppm corresponding to C of ₂ and 72.1 pp corresponding to C of —OCH of poly (3-hydroxybutyrate)
m corresponding to the carbon of the bonding portion between polyethylene terephthalate and poly (3-hydroxybutyrate).
New peaks appear at 5.8 ppm and 72.6 ppm, and 170.9 ppm corresponding to -C = O of polyethylene terephthalate and poly (3-hydroxybutyrate)
175.7 ppm corresponding to -C = O in the bonding portion of polyethylene terephthalate and poly (3-hydroxybutyrate) in addition to 175.7 ppm corresponding to -C = O
And a new peak appeared at 176.5 ppm, so that it was confirmed that the copolymerization occurred (see FIGS. 2 and 3).

Example 2 A copolymerized polyester was produced in the same manner as in Example 1 except that 3 parts by weight of polyethylene terephthalate and 7 parts by weight of poly (3-hydroxybutyrate) were used. Described.

Example 3 A copolymerized polyester was prepared in the same manner as in Example 1 except that 7 parts by weight of polyethylene terephthalate and 3 parts by weight of poly (3-hydroxybutyrate) were used. Described.

Example 4 Instead of poly (3-hydroxybutyrate), 3-hydroxyvalerate unit structure is 12 mol% of the total unit structure.
Having a number average molecular weight of 280,000.
Hydroxybutyrate-co-3-hydroxyvalerate) was used in the same manner as in Example 1 except that 5 parts by weight of hydroxybutyrate-co-3-hydroxyvalerate) was used.
Described in.

Example 5 Instead of polyethylene terephthalate, 5 parts by weight of polybutylene terephthalate having a number average molecular weight of 420,000, 5 parts by weight of poly (3-hydroxybutyrate) having a number average molecular weight of 350,000, and 8 parts of nitrobenzene were used.
Except that 9.9 parts by weight and 0.1 part by weight of tributyltin methoxide as a catalyst were added and reacted at a temperature of 160 ° C. for 24 hours, a copolymerized polyester was prepared in the same manner as in Example 1, and the physical property analysis results were obtained. Are shown in Table 3.

EXAMPLE 6 Instead of poly (3-hydroxybutyrate), poly (3-hydroxyvalerate having a number average molecular weight of 280000 and a 3-hydroxyvalerate unit structure of 12 mol% of the total unit structure was copolymerized.
A copolymerized polyester was produced in the same manner as in Example 5 except that 5 parts by weight of hydroxybutyrate-co-3-hydroxyvalerate) was used, and the physical property analysis results are shown in Table 3.

Example 7 Instead of poly (3-hydroxybutyrate), a poly (3-hydroxybutyrate) having a number average molecular weight of 190,000 and a 4-hydroxybutyrate unit structure copolymerized by 10 mol% of the total unit structure was used.
A copolymerized polyester was prepared in the same manner as in Example 5 except that 5 parts by weight of (hydroxybutyrate-co-4-hydroxybutyrate) was used, and the results of physical properties analysis are shown in Table 3.

[0027]

[Table 3]

[0028]

As can be seen from the results of the above examples, the present invention provides a copolyester having a low manufacturing unit price and excellent biodegradability.

[Brief description of drawings]

1 is an infrared spectroscopy spectrum of a copolyester produced in Example 1. FIG.

FIG. 2 is a ¹ H-nuclear magnetic resonance spectrum of the copolymerized polyester prepared according to Example 1.

FIG. 3 is a ¹³ C-nuclear magnetic resonance spectrum of the copolymerized polyester prepared according to Example 1.

 ─────────────────────────────────────────────────── ───Continued from the front page (72) Inventor Lee Mun Soo Republic of Korea Kyongguid, Suwon, Kwongsan-Kumaetan-Dong, Samsan Department 6-207 (72) Inventor Jun Hae Sun South Korea Kyung-gide, Suwon, Jangan-guk, Jun-ja-dong 313-1 (72) Inventor Lee Chang-soo Kyung-gide, Anyang, Dong-gang, Kwan-yang-2don, 1461-10, Shintayeyang Apartment B-206 (72) Inventor Jun Seung-gu Seoul, Republic of Korea, Dongdaemoon-gu, Hoegi-dong 65-13 (72) Inventor Woo Seong Yeel Seoul, Songpak, Moon-jean-dong, South Korea Olympic Family A compartment 219-601

Claims (7)

[Claims] 1. A polyester copolymer comprising a structure having an alkylene terephthalate as a repeating unit and a structure having a hydroxyalkanoate as a repeating unit, and having a structure represented by the following general formula (I). Embedded image Here, n is an integer of 10 or less, a, b and c are integers of 1 or more. 2. An aromatic polyester having an alkylene terephthalate structure as a repeating unit and an aliphatic polyester having a hydroxyalkanoate structure as a repeating unit are reacted at a temperature of 100 ° C. or higher in the presence of a solvent and a catalyst. A method for producing a copolyester having a structure represented by the following general formula (I). Embedded image Here, n is an integer of 10 or less. a, b and c are integers of 1 or more. 3. The method according to claim 2, wherein the aromatic polyester is polyethylene terephthalate having a number average molecular weight of 10,000 or more. 4. The method according to claim 2, wherein the aromatic polyester is polybutylene terephthalate having a number average molecular weight of 10,000 or more. 5. The method according to claim 2, wherein the aliphatic polyester is poly (3-hydroxybutyrate) biosynthesized by microbial fermentation. 6. The production of a copolymerized polyester according to claim 2, wherein the aliphatic polyester is poly (3-hydroxybutyrate-co-3-hydroxyvalerate) biosynthesized by microbial fermentation. Method. 7. The production of a copolymerized polyester according to claim 2, wherein the polyester is poly (3-hydroxybutyrate-co-4-hydroxybutyrate) biosynthesized by microbial fermentation of the aliphatic polyester. Method.