JPH06220179A - Production of poly-3-hydroxybutylate - Google Patents

Abstract

PURPOSE:To directly obtain the subject polymer useful for improving performance of a biodegradable plastic raw material derived from a microorganism at a low cost from inexpensive materials by reacting propylene oxide with carbon monoxide in the presence of a catalyst. CONSTITUTION:Propylene oxide is made to react with carbon monoxide in the presence of a catalyst (preferably a cobalt carbonyl complex such as dicobalt octacarbonyl), preferably at 50-150 deg.C under 10-200 atmospheric pressure, usually for 2-50hr to provide the objective polymer. Furthermore, as the reactional solvent, an aromatic hydrocarbon such as benzene or a alkane halide such as chloroform is preferably used. The reaction is preferably carried out in the absence of water.

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 poly-3-hydroxybutyrate, and more particularly to poly [(R, S) useful for improving the performance of biodegradable plastic materials produced by microorganisms. -3-hydroxybutyrate].

[0002]

2. Description of the Related Art Demand for plastics, which are light and strong, has been growing more and more in recent years, and their production volume has increased to over 10 million tons per year in Japan alone.
Along with that, the amount of discarded plastics has increased rapidly, which has become a new social problem. In other words, plastic is chemically stable and will not rot when buried, and since it is bulkier than its weight, there is no landfill for treatment. In addition, since plastic has a high heat of combustion per unit weight, it will damage the furnace when incinerated, and chlorine-based plastics such as polyvinyl chloride and polyvinylidene chloride, which are commonly used at home, produce dioxin with high carcinogenicity during combustion. , Has been regarded as a problem.

Therefore, it is desired to recycle plastics, and although it has been actively carried out in recent years in factories where the origin is relatively clear, plastic products once on the market are collected, transported, sorted and washed. Currently, most of them are not recycled because they require a lot of labor and cost. In order for recycling to function effectively, it is important to create a social system, but society is not mature enough to accept it.

Therefore, biodegradable plastics have been attracting attention in recent years as one of the measures for processing plastic wastes. Biodegradable plastic is a material that is decomposed by microorganisms and rapidly decomposes in an appropriate decomposition environment. Among them, aliphatic polyester (poly-3
-Hydroxybutyrate) has attracted attention as a substitute material for general-purpose plastics due to its thermoplasticity and excellent biodegradability.

However, poly-3 produced by microorganisms
-Hydroxybutyrate (hereinafter abbreviated as P3HB)
Has a defect that the structural unit is only the D-form and has high stereoregularity, so that the crystallinity is high and the obtained molded product is hard and brittle. Therefore, it was never used as a general-purpose product. Until now, as a measure against this, 2
Two methods have been proposed, and one is a method of causing a microorganism to produce a copolymer, as disclosed in JP-A-61-293385 and JP-A-63-269989. According to this method, it is possible to inhibit the high stereoregularity of the homopolymer by making it a copolymer, it is possible to improve the property of being hard and brittle, it is possible to provide an excellent biodegradable material, to the microorganisms Since it is produced, it is difficult to keep the composition of the copolymer constant, and there is a drawback that the properties vary greatly depending on the lot. In addition, although the properties are improved by copolymerization, the structural unit is only the D-form for production by microorganisms, and deterioration due to crystallization still occurs after molding.

Another method is chemically synthesized poly-3.
-Hydroxybutyrate (hereinafter referred to as random P3HB) is polymer-blended to inhibit crystallization of P3HB derived from a microorganism based on high stereoregularity (Japanese Patent Application No. 3-079118). Here, the random P3HB means a polymer in which structural units derived from D (-)-3-hydroxybutyric acid and L (+)-3-hydroxybutyric acid are randomly bonded. The polymer obtained by the microorganism is optically active and highly crystalline, whereas the polymer obtained by this chemical synthesis is optically inactive and has flexibility. Such a random P
The method of blending 3HB has an advantage that the composition can always be kept constant because the blending ratio of blending components can be freely determined, but the problem is that random P3HB is synthesized via lactone and thus the cost is high. There is.

Generally, there are various methods for synthesizing lactones,
A typical example is "Models of Biopolymers by Ring-Openi
ng Polymerization "[Stanislaw Penczek, CRC Press,
Inc. Boca Ration, Florida (1990)], by the condensation cyclization reaction of β-substituted acids or the addition reaction of ketene with aldehydes or ketones. However, β-substituted acids and ketene are not industrially used general-purpose products that are synthesized in large quantities, and the production process thereof is also complicated. Therefore, the production method is extremely high in the synthesis method via lactone. There was a flaw. Therefore, a new method for producing random P3HB that does not pass through a lactone has been desired.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method which can be manufactured at low cost, instead of the conventional method for manufacturing random PHB via lactone.

[0009]

As a result of intensive studies to solve the above-mentioned problems of the prior art, the present inventors have found that propylene oxide is directly reacted with carbon monoxide in the presence of a catalyst. It has been found that random P3HB can be synthesized. The gist of the present invention is a method for producing poly-3-hydroxybutyrate, which comprises reacting propylene oxide with carbon monoxide in the presence of a catalyst. Suitably, the above reaction is carried out in a solvent under heat and pressure.
The catalyst used is preferably a carbonyl complex of a Group VIII transition element, and the solvent is preferably an alkyl halide or an aromatic hydrocarbon.

[0010]

In the method of the present invention, propylene oxide is reacted with carbon monoxide in the presence of a catalyst to cause carbonylation and polymerization, whereby random P3HB can be synthesized. This reaction is preferably carried out in a solvent under heat and pressure. Propylene oxide used as a raw material in the method of the present invention is an inexpensive general-purpose product having a wide range of industrial applications.

The catalyst used is not limited, but is preferably a carbonyl complex of a transition element of Group VIII,
Particularly, a carbonyl complex of cobalt, iron or nickel is preferable. Specific examples include dicobalt octacarbonyl, tetracobalt dodecacarbonyl, dodecacarbonyl triiron, enneacarbonyldiiron, pentacarbonyliron, nickel carbonyl and the like. Further, a carbonyl complex in a form in which coordinated CO is partially substituted with triphenylphosphine or the like before or during the reaction is also included.

In the case of the above carbonyl complex, the amount of the catalyst added is preferably in the range of 0.1% by weight to 2% by weight with respect to propylene oxide. If the addition amount is large, not only the catalyst cost but also the cost required to generate the generated random P3HB is economically disadvantageous. On the contrary, if the addition amount is small, the reaction takes a long time and the reaction apparatus becomes large with respect to the treatment amount, which is also economically disadvantageous.

If the reaction temperature is too low, the reaction proceeds slowly,
On the other hand, if it is too high, propylene oxide is isomerized to acetone and the yield is lowered, so that the range of 50 to 150 ° C. is preferable. The reaction pressure is preferably high in order to increase the reaction rate, but it is 10 to 20 in consideration of the equipment cost and the reaction rate.
A pressure of about 0 atm is practically appropriate. In the case of the batch type, since carbon monoxide having a chemical equivalent amount or more to the reaction with propylene oxide is required, a corresponding pressure is required.

The reaction time varies depending on the equipment, the amount of catalyst added and other reaction conditions, but it is usually 2 to 50 hours. As the solvent, it is desirable to use aromatic hydrocarbons such as benzene, toluene and xylene, and halogenated alkanes such as chloroform and dichloromethane. However, as the aromatic hydrocarbon, aromatic hydrocarbons containing a substituent having no reactivity under the present reaction conditions can be used, but phenols and nitro compounds having reactive hydroxyl groups such as phenol and cresol, Also, acids such as benzoic acid cannot be used.

It is desirable to avoid the presence of water during the reaction as much as possible. This is because water promotes ring opening of the lactone produced by carbonylation and hinders polymerization. The poly-3-hydroxybutyrate synthesized by the above method is a polymer having R-form and S-form at random in its structural unit.

According to the present invention, since inexpensive propylene oxide is used as a raw material and the process is simple, random P3HB can be produced at low cost. Random P3HB
Can be mixed with microorganism-derived P3HB to improve the physical and physical defects of P3HB while maintaining the biodegradability of P3HB. Therefore, the ability to produce random P3HB at low cost by the method of the present invention is very advantageous in terms of cost in providing a biodegradable polymer that can be used practically.

[0017]

【Example】

[0018]

Example 1 50 g of propylene oxide, 100 ml of benzene and 0.5 g of dicobalt octacarbonyl were added to an electromagnetic stirring autoclave having an internal volume of 1 liter. After replacing the inside with nitrogen, carbon monoxide was injected under pressure up to 90 kgf / cm ² G with stirring at room temperature at a rotation speed of 500 rpm. Furthermore, after raising the temperature to 75 ° C., the reaction was continued for 10 hours.
After the reaction was completed, the reaction gas was cooled to room temperature, the reaction gas was discharged, the system was thoroughly replaced with nitrogen, and then the contents of the autoclave were recovered. The collected contents were filtered to separate a solid matter and a solution, and then the solution was transferred to a rotary evaporator to remove unreacted propylene oxide and the solvent under reduced pressure. The contents of the flask were dissolved in 100 ml of chloroform, placed in a separating funnel, and thoroughly washed with 100 ml of 0.1N hydrochloric acid solution. Further, it was washed with 100 ml of distilled water until the aqueous phase of the separating funnel became neutral.

When the contents in the oil layer of the separating funnel were separated and chloroform was completely removed, 26.3 g of a viscous liquid was obtained. When this substance was measured by ¹ H-NMR, the spectrum shown in FIG. 1 was obtained, and as a result of identification, random P3 was obtained.
It was HB. Furthermore, when the molecular weight is measured by GPC,
The weight average molecular weight was 10,000.

[0020]

Example 2 The reaction was carried out in the same manner as in Example 1 except that carbon monoxide was injected under pressure up to 30 kgf / cm ² G to obtain 19.4 g of a viscous liquid. When this substance was measured by ¹ H-NMR, the same spectrum as in Example 1 was obtained, and random P
It was identified as 3HB. Furthermore, when the molecular weight was measured by GPC, the weight average molecular weight was 7,000.

[0021]

[Example 3] The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 50 ° C to obtain 15.1 g of a viscous liquid. When this substance was measured by ¹ H-NMR, the same spectrum as in Example 1 was obtained, and it was identified as random P3HB.
Furthermore, when the molecular weight is measured by GPC, the weight average molecular weight is
It was 8,000.

[0022]

Example 4 The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 150 ° C., and 22.7 g of a viscous liquid was obtained. When this substance was measured by ¹ H-NMR, the same spectrum as in Example 1 was obtained, and it was identified as random P3HB. Furthermore, when the molecular weight was measured by GPC, the weight average molecular weight was 11,000.

[0023]

Example 5 Example 1 except that the solvent is chloroform.
The reaction was carried out in the same manner as above to obtain 22.7 g of a viscous liquid.
When this substance was measured by ¹ H-NMR, the same spectrum as in Example 1 was obtained, and it was identified as random P3HB. Furthermore, when the molecular weight was measured by GPC, the weight average molecular weight was 8,000.

[0024]

[Example 6] The reaction was performed in the same manner as in Example 1 except that the amount of the catalyst added was 0.1 g, to obtain 20.5 g of a viscous liquid. When this substance was measured by ¹ H-NMR, the same spectrum as in Example 1 was obtained, and it was identified as random P3HB. Furthermore, when the molecular weight was measured by GPC, the weight average molecular weight was 8,000.

[0025]

According to the present invention, random propylene oxide is directly used from inexpensive propylene oxide which is widely used in industry.
3HB can be synthesized. This method is advantageous in cost because it can be produced from an inexpensive raw material in a simple process, unlike the conventional method in which a lactone that requires a complicated production process is used. Since the obtained random P3HB is useful as a blending component for improving the physical properties of P3HB derived from a microorganism known as a biodegradable polymer, the method of the present invention is very useful for practical application of the biodegradable polymer. .

[Brief description of drawings]

FIG. 1 is a diagram showing a ¹ H-NMR spectrum of a polymer obtained in an example.

Claims (2)

[Claims] 1. A method for producing poly-3-hydroxybutyrate, which comprises reacting propylene oxide with carbon monoxide in the presence of a catalyst. 2. The method according to claim 1, wherein the reaction is carried out in a solvent under heat and pressure.