JP3342578B2 - Method for producing aliphatic polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high molecular weight aliphatic polyester which is decomposed by microorganisms in soil and can be used as a molded article.

[0002]

2. Description of the Related Art Aliphatic polyesters, such as polyethylene succinate (PES), polyethylene adipate (PEA) and polyethylene, produced by melt polycondensation of α, ω-aliphatic diol and α, ω-aliphatic dicarboxylic acid. Butylene succinate (PBS) is a polymer that has been known for a long time, can be manufactured at low cost, and has been confirmed to be decomposed by microorganisms in soil burial tests [International Biodetertionation Bulletin (Int. Biodetetn. Bull.), Vol. 11, p. 127 (1975) and Polymer Science Technology (Polym. Sci. Technol.), Vol. 3, p. 61 (1973).
However, these polymers have poor thermal stability and cause a decomposition reaction at the time of polycondensation.
Only a molecular weight of about 6,000 (concentration of 0.5 g / deciliter using chloroform, reduced specific viscosity ηsp / c measured at 30 ° C. of 0.3 or less) is obtained. Was not enough.

In order to increase the molecular weight of these aliphatic polyesters, it has been reported to treat them with diisocyanates such as hexamethylene diisocyanate and toluene diisocyanate [Polym. J. , Vol. 2, p. 387 (1971) and JP-A-4-189822]. However, although these methods have the effect of increasing the molecular weight, the reaction step is usually performed in two stages, and the process becomes complicated. In addition, the obtained polyester has a problem that, in addition to a slight decrease in its crystallinity and melting point, a urethane bond is contained in the molecule, so that the biodegradability is slightly inferior. .

Further, it has been proposed to synthesize an aliphatic polyester by direct polycondensation using a titanium oxyacetylacetonate or an alkoxytitanium compound as a catalyst (Japanese Patent Application Laid-Open Nos. 5-70566 and 5-7).
0574). However, in these methods, since a titanium-based catalyst is used, if the amount of the catalyst is not limited to a small amount, the resulting polymer is undesirably colored, and the molecular weight is 15,000 because the amount of the catalyst is limited to a small amount.
There is a problem that it increases only to about 0. Further, Japanese Patent Application Laid-Open No. 6-41288 discloses a method of preventing coloring by adding a phosphorus compound after the completion of the aliphatic polyester synthesis reaction, but the molecular weight still increases only up to about 20,000. Therefore, it was insufficient for use as a molded article.

Further, the polycondensation reaction is carried out in an amount of 0.005 to 0.1.
By performing the reaction under a high vacuum of mmHg, the molecular weight is 40,0.
A method for producing an aliphatic polyester of about 00 has been proposed (see JP-A-5-310898). However, in this method, not only a specific vacuum pump must be used but also the melting point is considerably lowered. There was a problem.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present inventors have developed a polybutylene succinate using a germanium compound which is also contained in ginseng and which is very safe and can be used for food-related products as a catalyst. An attempt was made to synthesize a high-molecular-weight, dull, and transparent aliphatic polyester based on a nitrate, but the molecular weight was limited to about 25,000, and it was impossible to obtain a substantially moldable polymer. .

[0007] The present invention solves the above problems,
An object of the present invention is to provide a method for producing a high-molecular-weight aliphatic polyester based on polybutylene succinate, which has been increased to a molecular weight that can be used as a molded article, without impairing the inherent property of biodegradability.

[0008]

Means for Solving the Problems The present inventors have made various studies to solve the above-mentioned problems, and as a result, the present invention has been made to solve the above-mentioned problems by manufacturing using a germanium compound and a specific metal compound as a catalyst. Were obtained, and based on this knowledge, the present invention was reached.

That is, the present invention relates to an aliphatic polyester obtained by reacting succinic acid or its anhydride with 1,4-butanediol to obtain an oligomer, and then subjecting the obtained oligomer to polycondensation in the presence of a catalyst. In producing, a germanium compound as a catalyst, titanium, antimony,
It is another object of the present invention to provide a method for producing an aliphatic polyester, characterized by using at least one metal compound selected from zinc, magnesium and zirconium .

Hereinafter, the present invention will be described in detail.

First, in the present invention, it is necessary to react succinic acid or its anhydride with 1,4-butanediol to obtain an oligomer. The charge ratio of succinic acid or its acid anhydride to 1,4-butanediol at that time is usually preferably from 1: 1 to 1: 2.2 in terms of a molar ratio, and preferably from 1: 1.01 to 1: 2.2. : 1.6 is more preferable, and 1: 1.05 to 1: 1.5 is most preferable.

In the present invention, dicarboxylic acids such as oxalic acid, adipic acid, glutaric acid, suberic acid, and azelaic acid may be used in addition to succinic acid or its acid anhydride as long as the physical properties of the aliphatic polyester obtained are not impaired. , Sebacic acid, dodecane diacid, eicosane diacid or the like or an acid anhydride thereof can be used in combination. An aromatic dicarboxylic acid such as terephthalic acid or isophthalic acid can be used in combination as long as the biodegradability is not hindered. Further, a polyvalent carboxylic acid, for example, (trimellitic anhydride), pyromellitic anhydride (anhydride) and the like can be used in combination.

On the other hand, as diols, in addition to 1,4-butanediol, ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, 1,5-pentanediol, 1,10-decanediol, neopentyl glycol, At least one diol selected from hexamethylene glycol, 1,4-cyclohexanedimethanol and the like can be used in combination, and the mixing ratio in this case is 1,4-butanediol of 50 mol% or more. It is more preferably at least 75 mol% from the viewpoint of not lowering the melting point or crystallinity. In addition, polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol and the like can be used in combination. Further, oxycarboxylic acids such as malic acid, citric acid and tartaric acid can be used in combination.

In the present invention, when synthesizing an oligomer by transesterification, a metal compound may be added as a catalyst. The metal compound at that time is the organometallic compound,
Organic acid salts, metal complexes, metal alkoxides, metal oxides,
It is used as a metal hydroxide, a carbonate, a phosphate, a sulfate, a nitrate, a chloride and the like, and among them, it is preferable to use an acetate or an acetylacetone metal complex metal oxide. The amount of the catalyst at this time is preferably 0.02 to 1 part by weight per 100 parts by weight of the aliphatic polyester to be produced.

The reaction conditions for preparing the oligomer by transesterification are preferably in the range of 120 to 250 ° C. for 1 to 10 hours, in the range of 150 to 220 ° C. for 2 to 5 hours, at atmospheric pressure, under inert pressure. It is more preferable to carry out the reaction under a gas stream, particularly under a nitrogen stream.

Next, in the present invention, the oligomer obtained above as essential components a germanium compound, titanium
It is necessary to perform polycondensation in the presence of a mixed catalyst with at least one metal compound selected from the group consisting of iron, antimony, zinc, magnesium and zirconium .

As the germanium compound, tetrabutoxygermanium, tetraethoxygermanium, tetraphenylgermanium, tetrabutylgermanium,
Germanium oxide and the like can be mentioned. Among them, tetrabutoxygermanium, tetraethoxygermanium and the like are preferable since they have high catalytic activity and can be obtained at low cost.

Further, titanium, antimony, zinc, magnesium, zirconium used in combination with a germanium compound.
As the at least one metal compound selected from the group consisting of aluminum, it is desirable to use them in the form of their acetylacetone metal complexes, alkoxy metal compounds, metal salts of organic acids, and the like. Specifically, magnesium acetylacetonate
G, zinc acetylacetonate, zinc acetate, tetrabute
Xyzirconium and the like , and magnesium acetylacetonate, zinc acetylacetonate, tetrabutoxyzirconium and the like are preferable in terms of increasing the molecular weight in a short time.

The mixing ratio of the metal compound and the germanium compound is such that the molar ratio of the germanium compound is 2%.
0 to 95 mol%, other metal compounds are 80 to 5 mol%
And the germanium compound is preferably 30 to 8
Optimally, 0 mol% and other metal compounds are 70 to 20 mol%. Germanium compound is 20 mol%
If it is less than or equal to 95 mol%, it tends to be difficult to obtain a polymer having a target molecular weight, which is not preferable.
Also, highly active catalysts such as titanium and antimony compounds, for example, tetrabutyl titanate, tetraisopropoxy titanium, titanium (oxy) acetylacetonate, dibutoxydiacetacetoxy titanium, tributoxyantimony, triethoxyantimony, antimony acetate, etc. When used, the mixing ratio with the germanium compound is 80 to 99 mol% of the germanium compound, titanium,
The content of the antimony compound is preferably 20 to 1 mol%. In this case, the titanium or antimony compound is 20 mol%.
If the ratio exceeds the above, coloring may occur, and the advantage of using a mixed catalyst with a germanium compound is reduced. If the amount is less than 1 mol%, it tends to be difficult to obtain a polymer having a desired molecular weight, which is not preferable.

The amount of the catalyst used at that time is as follows:
0.1 parts by weight per 100 parts by weight of the aliphatic polyester produced.
The amount is preferably from 01 to 5 parts by weight, more preferably from 0.05 to 2 parts by weight. When the amount of the catalyst is less than 0.01 part by weight, the effect as a catalyst is weakened, and it is difficult to obtain a polymer having a target molecular weight. Increases in the amount used, which is not preferable from the viewpoint of safety. Further, these catalysts may be added immediately before the glycolation or may be added before the esterification.

In the case of polymerization after deliquoration, a phosphorus compound can be added as a coloring inhibitor. Phosphorus compounds include phosphoric acid, phosphoric anhydride, polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid, phosphorous acid, hypophosphorous acid, tripolyphosphoric acid, bis (2,4-dibutylphenyl) pentaerythritol diphos Spirophosphorus compounds represented by fate and their metal salts, ammonium salts, chlorides, bromides, sulfides, esterified compounds, etc., are particularly preferred.Phosphoric acid, polyphosphoric acid, metaphosphoric acid, bisphosphate (2,4-dibutylphenyl) pentaerythritol diphosphate and the like. These phosphorus compounds may be used alone or as a mixture of two or more. Further, the amount of the phosphorus compound used at that time is preferably 0.001 to 1 part by weight, more preferably 0.01 to 0.5 part by weight, per 100 parts by weight of the aliphatic polyester to be produced. Further, these phosphorus compounds may be added immediately before deglycolization or may be added before esterification.

The reaction conditions for the polycondensation are as follows.
Under reduced pressure of 01 to 10 mmHg,
It is preferably carried out for 10 hours, more preferably for 1-5 hours at 220-260 ° C. under reduced pressure of 0.1-1 mmHg.

According to the present invention, a polymer having a number average molecular weight in terms of polystyrene of 30,000 or more determined by gel filtration chromatography (GPC) can be obtained.

The aliphatic polyester produced as described above is thermoplastic and has no coloring because it uses a germanium compound as a catalyst. In addition, since it has moldability, it can be applied to various uses. For example, as a biodegradable polymer, it can be processed into films, fibers, sheets, or the like, and used as various bottles, shopping bags, packaging materials, synthetic yarns, fishing lines, fishing nets, nonwoven fabrics, agricultural multi-films, and the like.

The aliphatic polyester produced as described above has excellent transparency when used as a film or sheet, and uses a compound which is very safe for the human body as a catalyst. It is optimal to use

[0026]

The present invention will be specifically described below with reference to examples. In addition, each value was calculated | required as follows.

(1) Number average molecular weight (Mn) in terms of polystyrene determined by GPC Using a GPC measuring device manufactured by Waters,
One each of Waters ultrastyragel with an average pore diameter of 10 ³ and 10 ⁴ mm, a total of two 7.8 mmφ × 30 cm connected
Measurements were made at 35 ° C. using a long column and using chloroform as eluent.

Note that polystyrene was used as a standard.

(2) Reduced specific viscosity (ηsp / c) The viscosity of the polymer solution at a concentration of 0.5 g / deciliter was measured using an Ubbelohde viscometer, which was used as a measure of the molecular weight. In addition, it measured at 30 degreeC using chloroform as a solvent.

(3) Melting point The melting point was measured at a heating rate of 20 ° C./min using a thermal analyzer (DSC-7) manufactured by Perkin Elmer.

Example 1 In a three-necked flask equipped with a stirrer, a Wigrew fractionating tube and a gas introducing tube, 47.2 g (0.4 mol) of succinic acid was added.
39.7 g (0.44 mol) of 1,4-butanediol was added and immersed in a hot water bath. The temperature of this hot water bath was raised to 200 ° C,
Nitrogen was slowly flowed into the melt, and the generated water and excess glycol were distilled off at 200 ° C. for 3 hours to obtain an oligomer.

Next, tetrabutoxygermanium 0.1.
29g (8.0 × 10 ^-4 mol) and zinc acetylacetonate monohydrate 0.11g (4.0 × 10 ^-4 mol) was added, the temperature is held at 220 ° C., under a reduced pressure of 0.5mmHg For 2 hours and further at 240 ° C. under a reduced pressure of 0.5 mmHg for 2 hours to obtain a viscous polymer liquid.

When this polymer was cooled to room temperature, it became a white polymer, ηsp / c was 1.03 (concentration: 0.5 g / deciliter, 30 ° C., in chloroform), and the melting point was 117 ° C. The polystyrene equivalent number average molecular weight (Mn) determined by GPC was 51,000.

Example 2 Instead of 0.11 g of zinc acetylacetonate monohydrate, 0.09 g of magnesium acetylacetonate was used.
(4.0 × 10 ⁻⁴ mol), and a white polymer was obtained in exactly the same manner as in Example 1. This ηsp / c is 1.
07 (concentration: 0.5 g / deciliter, 30 ° C., in chloroform), melting point: 116 ° C. Also, GP
C, the number average molecular weight in terms of polystyrene (M
n) was 53,000.

Example 3 A three-necked flask equipped with a stirrer, a Wigrew fractionating tube and a gas introducing tube was charged with 40.0 g (0.4 mol) of succinic anhydride and 31.7 g of 1,4-butanediol (0 mol). .35 mol) and 5.5 g (0.09 mol) of ethylene glycol, and immersed in a hot water bath. The temperature of this hot water bath was raised to 200 ° C,
Nitrogen was slowly flowed into the melt, and the generated water and excess glycol were distilled off at 200 ° C. for 3 hours to obtain an oligomer.

Then, bis (2,4-dibutylphenyl) pentaerythritol diphosphate 0.025
g, 0.20 g of tetraethoxygermanium (8.0 ×
10 ^-4 mol) and 0.31 g of tetrabutoxyzirconium
(8.0 × 10 ⁻⁴ mol), the temperature was kept at 220 ° C., and the pressure was reduced to 0.5 mmHg under reduced pressure for 2 hours and further 240 ° C.
By heating at a temperature of 0 ° C. under a reduced pressure of 0.5 mmHg for 2 hours, a viscous polymer liquid was obtained.

When this polymer was cooled to room temperature, it became a white polymer, ηsp / c was 1.01 (concentration: 0.5 g / deciliter, 30 ° C., in chloroform), and the melting point was 96 ° C. The number average molecular weight (Mn) in terms of polystyrene determined by GPC was 53,000.

Example 4 In a three-necked flask equipped with a stirrer, a Wigrew fractionating tube and a gas introducing tube, 32.0 g (0.32 mol) of succinic acid, 11.7 g (0.08 mol) of adipic acid, 1,4
-Butanediol 39.7 g (0.44 mol)
Soaked in a hot water bath. The temperature of the water bath was raised to 200 ° C., nitrogen was slowly flowed into the melt, and water and excess glycol generated at the temperature of 200 ° C. for 3 hours were distilled off to obtain oligomers.

Next, 0.025 g of polyphosphoric acid and 0.20 g of triethoxygermanium (8.0 × 10 ^-4 mol)
And 0.18 g of magnesium acetylacetonate (8.
0 × 10 ^-4 mol), keeping the temperature at 220 ° C.
Under a reduced pressure of 0.5 mmHg for 2 hours, 240 ° C.
By heating under reduced pressure of 0.5 mmHg for 2 hours, a viscous polymer liquid was obtained.

When this polymer was cooled to room temperature, it became a white polymer, ηsp / c was 1.09 (concentration: 0.5 g / deciliter, 30 ° C., in chloroform), and melting point was 98 ° C. The number average molecular weight (Mn) in terms of polystyrene determined by GPC was 55,000.

Example 5 Instead of 0.11 g of zinc acetylacetonate monohydrate, 0.014 g of tetra-n-butyl titanate (4.
(0 × 10 ⁻⁵ mol), and a white polymer was obtained in exactly the same manner as in Example 1. This ηsp / c is 1.16
(Concentration: 0.5 g / deciliter, 30 ° C., in chloroform), and the melting point was 117 ° C. The number average molecular weight (Mn) in terms of polystyrene determined by GPC was 54,000.

Example 6 Instead of 0.11 g of zinc acetylacetonate monohydrate, 0.014 g of tributoxyantimony (4.0 × 1
0 except ^-5 mol) using the obtain a white polymer in the same manner as in Example 1. This ηsp / c was 1.12 (concentration: 0.5 g / deciliter, 30 ° C., in chloroform), and the melting point was 117 ° C. The polystyrene equivalent number average molecular weight (Mn) determined by GPC is 53,
000.

Comparative Example 1 47.2 g (0.4 mol) of succinic acid was placed in a three-necked flask equipped with a stirrer, a Wigrew fractionating tube, and a gas introducing tube.
39.7 g (0.44 mol) of 1,4-butanediol was added and immersed in a hot water bath. The temperature of this hot water bath was raised to 200 ° C,
Nitrogen was slowly flowed into the melt, and the generated water and excess glycol were distilled off at 200 ° C. for 3 hours to obtain an oligomer.

Then, tetrabutoxygermanium 0.1.
29 g (8.0 × 10 ^-4 mol) were added and the temperature was increased to 220 ° C.
2 hours under reduced pressure of 0.5 mmHg,
By heating at 240 ° C. under a reduced pressure of 0.5 mmHg for 4 hours, a polymer liquid was obtained.

The ηsp / c of this polymer was 0.62 (concentration: 0.5 g / deciliter, 30 ° C., in chloroform), and the number average molecular weight (Mn) in terms of polystyrene determined by GPC was 25,000. Was.

Comparative Example 2 Instead of 0.29 g of tetrabutoxygermanium, 0.11 g of zinc acetylacetonate monohydrate (4.0 ×
^10-4 mol), and a white polymer was obtained in exactly the same manner as in Comparative Example 1. The ηsp / c of this polymer was 0.41 (concentration: 0.5 g / deciliter, at 30 ° C. in chloroform), and the number average molecular weight (Mn) in terms of polystyrene determined by GPC was 14,000.

Comparative Example 3 0.014 g of tetra-n-butyl titanate (4.0 × 1) was used instead of 0.29 g of tetrabutoxygermanium.
0 except ^-5 mol) using the in the same manner as in Comparative Example 1, to obtain a white polymer. The ηsp / c of this polymer is 0.1.
51 (concentration: 0.5 g / deciliter, 30 ° C., in chloroform), and the number average molecular weight (Mn) in terms of polystyrene determined by GPC was 17,000.

[0048]

According to the present invention, a transparent aliphatic polyester having a high molecular weight that can be used as a molded article and having no dullness can be easily produced. Also,
Since the aliphatic polyester obtained by the present invention uses a catalyst safe for the human body, it can be used for food bottles and films.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (1)

(57) [Claims] An oligomer is obtained by reacting succinic acid or its anhydride with 1,4-butanediol, and then subjecting the resulting oligomer to polycondensation in the presence of a catalyst to produce an aliphatic polyester. , A germanium compound as a catalyst, titanium, antimony, zinc, magnesium
And at least one metal compound selected from the group consisting of zirconium and zirconium .