JPH08301999A - Production of biodegradable aliphatic polyester carbonate - Google Patents

Abstract

PURPOSE: To provide a biodegradable aliph. polyester carbonate which, when formed into a film or the like, causes no surface precipitate and possesses excellent appearance and heat stability. CONSTITUTION: A biodegradable aliph. polyester carbonate having a wt. average mol.wt. of not less than 100000 and a cyclic oligomer content of not more than 0.6wt.% is produced by reacting a aliph. dihydroxy compd. composed mainly of 1,4-butanediol with an aliph. dicarboxylic acid compd. composed mainly of succinic acid to prepare an aliph. polyester oligomer, which is then reacted with diphenyl carbonate. It can provide a molding having an excellent appearance and is suitable for preparing a molding such as a film, sheet, foam, or fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a biodegradable aliphatic polyester carbonate resin which has no surface deposits when formed into fibers, films, sheets and other molded articles and has excellent appearance characteristics and heat stability. And a manufacturing method thereof. The aliphatic polyester carbonate obtained by the present invention has excellent appearance properties after molding, and further has biodegradability (biodegradability), so it can be used for packaging materials, agricultural fields, fisheries fields, other molded articles, etc. It is something. For example, in the agricultural field, it can be used as a mulch film that covers the soil surface to keep the soil warm, pots and strings for planting trees, as a fertilizer coating material, or in the fishing field for fishing lines, fishing nets, and even medical fields. It can be used as a hygiene material for medical materials and sanitary products.

[0002]

2. Description of the Related Art Conventionally, as a polyester carbonate, a polyester carbonate using an alicyclic compound or a polyester carbonate using an aromatic compound and an aliphatic compound usually has a high melting point or a high glass transition point. Therefore, it is known that it can be used as a molded body. However, they are generally not biodegradable and are not classified as biodegradable polymers. The term "biodegradable polymer" as used herein means, for example, a property in which a polymer is decomposed and disappears by the action of microorganisms when a molded article is left in soil or water. Classified as a biodegradable polymer is an aliphatic polyester carbonate produced by a ring-opening polymerization method using a cyclic monomer. These are composed of a hydroxycarboxylic acid unit and an aliphatic carbonate unit as constituent elements and are biocompatible and may be used in the medical field, but since they have hydrolyzability, their use as molded bodies is restricted. There is.

On the other hand, it is known to produce an aliphatic polyester carbonate from an aliphatic dicarboxylic acid, an aliphatic diol and a diaryl carbonate. However, the aliphatic polyester carbonate containing the aliphatic dicarboxylic acid and the aliphatic diol as constituent components is Generally, it has a low melting point and shows rubber-like properties, and although it is proposed to be used as a material for adhesives, sealing agents, coating coating agents, and polymer alloys with other resins, its main applications are However, it has not been found yet that it is used as a liquid low molecular weight material for urethane raw materials and is required to have a high molecular weight, and it is processed into a molded article such as a film, sheet or fiber and put to practical use.

The present inventors have found that the high molecular weight aliphatic polyester carbonate has biodegradability and can be used as various molded products such as films, sheets and fibers. These high molecular weight aliphatic polyester carbonates are polymers with good melt moldability, biodegradability, etc., but as a result of further research on physical properties, applications, etc. It was revealed that the deterioration of the appearance characteristics was observed due to the precipitates on the.

When the precipitate was analyzed, it was found to be a cyclic oligomer. For precipitation of the cyclic oligomer, for example, polyethylene terephthalate (PE
T.) (J. Polymer Sc
i. , Vol. 13, p. 406, 1954), it has been confirmed that surface precipitates are mainly cyclic trimers. The cyclic trimer has a large molecular weight and is difficult to be physically removed from PET by a reduced pressure treatment or the like. On the other hand, a solid-state polymerization method at a temperature equal to or lower than the melting point has been put into practical use as a method for obtaining a high molecular weight PET having a small content of cyclic oligomer. According to this method, the amount of cyclic trimer in PET is 0.3% by weight.
It is known that it can be reduced to some extent. The aliphatic polyester carbonate obtained by melt polycondensation of the aliphatic polyester oligomer and the diaryl carbonate is a polymer known per se. However, there is no mention of the inclusion of cyclic oligomers in the polymer and its removal. Generally, the aliphatic polyester carbonate has a low melting point and cannot secure a practical polymerization temperature for carrying out solid phase polymerization. Therefore, the solid phase polymerization method practically used in the PET described above is Not suitable for group polyester carbonates.

On the other hand, a method for improving the thermal stability of biodegradable aliphatic polyester is disclosed in JP-A-7-53700. That is, this method relates to synthesizing an aliphatic polyester whose terminal group is substantially a hydroxyl group and then removing a low molecular weight oligomer from a reaction product obtained by further reacting with a monoisocyanate compound. However, in this method, the number of reaction steps with monoisocyanate is increased, the steps are complicated, and since the polymerization catalyst remains in the polymer as it is, it is possible to sufficiently suppress the decrease in the molecular weight of the polymer during heating and melting. It's not a sufficient method. Therefore, it was necessary to develop a new method for reducing cyclic oligomers.

[0007]

The object of the present invention is to reduce surface precipitates to an amount that does not pose a practical problem when molded into fibers, films, sheets, and other molded articles, and to provide excellent appearance characteristics. The present invention is to provide a biodegradable aliphatic polyester carbonate having no problems in post-processing and application fields and a method for producing the same.

[0008]

The present inventors have found that an aliphatic polyester carbonate, particularly an aliphatic dihydroxy compound containing 1,4-butanediol as a main component and an aliphatic dicarboxylic acid compound containing succinic acid as a main component. As a result of diligent examination of the surface precipitates of the molded product of the aliphatic polyester carbonate obtained by melt-polycondensing the aliphatic polyester oligomer obtained from and diphenyl carbonate, the surface precipitate is mainly succinic acid and 1, Cyclic dimer consisting of 4-butanediol (each 2
It is a cyclic oligomer whose main component is (the one which has undergone a molecular reaction), and can be removed from the resin by adding and mixing a phosphorus compound after completion of the polymerization reaction and devolatilizing under reduced pressure at a temperature above the melting point. I found it. Further, they have found that by reducing the content of the cyclic oligomer in the aliphatic polyester carbonate to 0.6% by weight or less, it is possible to suppress deposits on the surface of the molded product, and the present invention has been completed.

That is, the present invention provides an aliphatic polyester oligomer comprising an aliphatic dihydroxy compound containing 1,4-butanediol as a main component and an aliphatic dicarboxylic acid compound containing succinic acid as a main component, and the oligomer and diphenyl. Obtained from carbonate, having a weight average molecular weight of 100,000 or more and a cyclic oligomer content of 0.6.
It is a biodegradable aliphatic polyester carbonate characterized by being less than weight%.

In the present invention, an aliphatic dihydroxy compound containing 1,4-butanediol as a main component is reacted with an aliphatic dicarboxylic acid compound containing succinic acid as a main component to obtain an aliphatic polyester oligomer, When obtaining an aliphatic polyester carbonate from an oligomer and diphenyl carbonate, after the polymerization reaction is completed, a phosphorus compound is added and mixed, and then the temperature is 130 to 300 ° C. and the degree of vacuum is 10
The method for producing a biodegradable aliphatic polyester carbonate is characterized in that the devolatilization treatment is performed under a condition of mmHg or less, and the cyclic oligomer content is set to 0.6% by weight or less.

The biodegradable aliphatic polyester carbonate according to the present invention is produced by using an aliphatic dihydroxy compound containing 1,4-butanediol as a main component and an aliphatic dicarboxylic acid compound containing succinic acid as a main component. It comprises a first step of obtaining an oligomer, a second step of reacting the aliphatic polyester oligomer obtained in the first step with diphenyl carbonate, and a third step of removing a cyclic oligomer from the obtained aliphatic polyester carbonate. It For convenience, the case where 1,4-butanediol and succinic acid are used as raw materials will be described below.

The first step is carried out at a temperature of 100 to 100 in the presence of a catalyst.
In the step of producing a polyester oligomer having a number average molecular weight (Mn) of 500 to 10000 at 250 ° C., preferably 150 to 220 ° C., while removing by-produced water and excess 1,4-butanediol during the reaction. is there. When the molecular weight of the polyester oligomer is higher than the above value, the proportion of carbonate bonds in the final polymer is remarkably low and the biodegradability is deteriorated. Therefore, it is not preferable to exceed the above molecular weight. However, the carbonate bond makes it possible to easily make the oligomer into a high molecular weight compound as a binder for the oligomer, and when it is not necessary to take biodegradability into consideration, a polyester oligomer having a molecular weight exceeding the above-mentioned molecular weight is used. Is also good. Further, when the molecular weight of the polyester oligomer is less than 500, the melting point of the final polymer is lowered and it cannot be used practically.

The pressure at which the above reaction is carried out is selected as the pressure at which the above reaction is achieved, and is 300 mmHg for the purpose of promoting the reaction.
The following reduced pressure may be used.

In the reaction of 1,4-butanediol with succinic acid in the first step, 1,4-butanediol is used in excess of the theoretical amount. Specifically, 1,4-butanediol is used in a molar ratio range of 1.05 to 2.00 with respect to 1 succinic acid. The more 1,4-butanediol, the longer the reaction time, but the smaller the acid value tends to be. The molecular weight, acid value, and residual amount of 1,4-butanediol of the obtained aliphatic polyester oligomer can be controlled by appropriately balancing the distillation rate of unreacted 1,4-butanediol and the reaction rate. ,
A realistic method is to combine the charged molar ratio, the catalyst, the temperature, the degree of reduced pressure, and the reaction time, or to blow an inert gas at an appropriate flow rate.

For example, by increasing the rate of increase in the degree of vacuum, the reaction time is shortened and 1,4 in the oligomer is reduced.
-The remaining amount of butanediol can be reduced, but the amount of unreacted carboxylic acid, that is, the acid value increases. An increase in the acid value is not preferable due to problems such as decomposition and coloration due to a side reaction of diphenyl carbonate. On the other hand, an increase in the amount of catalyst increases the reaction rate, but eventually causes a problem in the thermal stability of the polymer produced. Therefore, the reaction is carried out by adjusting the degree of pressure reduction in three stages using a small amount of catalyst. The first stage is carried out at atmospheric pressure, mainly with the removal of water produced by condensation. The second stage is the completion of the dehydration condensation reaction, that is, an aging step for reducing the acid value, which is 200 to 80 mm.
Water and a small amount of 1,4-butanediol are distilled off at a reduced pressure of about Hg. The third stage is a process of increasing the molecular weight by distilling off excess 1,4-butanediol, and the final step is 5 m.
The degree of reduced pressure is not more than mHg. The molecular weight, that is, the terminal hydroxyl value can be adjusted by adjusting the amount of 1,4-butanediol distilled. Terminal hydroxyl value is 20 ~ 200KOH
The range of mg / g is preferred.

The second step is a step of reacting the polyester oligomer obtained in the first step with diphenyl carbonate to obtain a high molecular weight substance, and the temperature is 150 to 250 ° C.
Preferably, it is a step of removing phenol and a small amount of 1,4-butanediol, a conversion product of 1,4-butanediol and the like, which are by-produced by the reaction, at 200 to 230 ° C. Here, the amount of diphenyl carbonate used is 0.45 to 0.55 times the molar amount of the terminal hydroxyl group of the polyester oligomer, and more preferably 0.
It is used in the range of 47 to 0.51 times the molar amount. The content of carbonate bonds in the obtained polyester carbonate is determined by the terminal hydroxyl value of the polyester oligomer, and is in the range of 1.8 to 33 mol%, preferably 3 to 25.
It is in the range of mol%. When the amount of carbonate bond increases, the biodegradability improves, but the melting point decreases, so it is necessary to control according to the application. Further, the polyester oligomer used here is not limited to one kind, and two or more kinds of polyester oligomers having different raw materials may be independently produced, and a block copolymer may be produced by mixing appropriate amounts. Is also possible.

In this step, if the reaction temperature is high, the polymerization reaction is fast, but the obtained polymer may be colored, and a temperature higher than the above range is not preferable. The reaction is carried out by gradually adjusting the degree of pressure reduction, if necessary, and finally it is preferable to reduce the pressure to 3 mmHg or less.

The aliphatic polyester carbonate after the completion of the second step contains 1 to 3% by weight of a cyclic oligomer. In addition, about 300 ppm of by-produced phenol and less than 20 ppm of unreacted diphenyl carbonate are contained. The third step in the production of the aliphatic polyester carbonate of the present invention is a step of removing the above cyclic oligomer from the aliphatic polyester carbonate obtained in the polymerization step.

In the removal of the cyclic oligomer in the production of the aliphatic polyester carbonate of the present invention, after the completion of the polymerization reaction, a phosphorus compound is added and mixed, and then volatilized under reduced pressure to distill off the cyclic oligomer. That is, a phosphorus-based compound was added to and mixed with a molten aliphatic polyester carbonate having reached a target molecular weight under a nitrogen atmosphere, and subsequently, devolatilized under reduced pressure with a device having a high surface renewal capacity to obtain a cyclic oligomer concentration. Is 0.6 wt% or less. In the removal process, the by-product phenol and unreacted diphenyl carbonate are removed at the same time as the cyclic oligomer, and the by-product phenol is 20 p
At a concentration of pm or less, unreacted diphenyl carbonate becomes 10 ppm or less. Cyclic oligomer concentration is 0.6
When the content is more than 10% by weight, white crystals are deposited on the surface of the film and sheet after molding after a storage period of about 1 month, impairing transparency. Moreover, in the amount of phenol of 20 ppm or more,
There is a problem of phenol odor during molding, which is not preferable in terms of work.

In the method of the present invention, since the aliphatic polyester carbonate is in a molten state and is operated under reduced pressure, the addition of a phosphorus compound is indispensable in order to suppress the fluctuation of the molecular weight of the polymer. That is, the addition of the phosphorus-based compound suppresses the fluctuation of the molecular weight during the oligomer removing operation and suppresses the regeneration of the cyclic oligomer. It is also effective in improving the thermal stability of the polymer in the molten state. The addition amount of the phosphorus-based compound is 0.3 to 10 times by mole, preferably 0. 1 times, with respect to 1 mole of the catalyst used in the first and second steps.
It is used in a range of 5 to 5 times by mole, and phosphoric acid, polyphosphoric acid, phosphorous acid and their esters are preferably used as the phosphorus compound in the present invention. A high temperature and a high degree of vacuum are preferable for removing the cyclic oligomer, and the operating temperature is 13
0 to 300 ° C., preferably 180 to 280 ° C., the degree of reduced pressure is 10 mmHg or less, preferably 5 mmHg or less,
More preferably, it is performed at 2 mmHg or less.

The removal of the cyclic oligomer in the production of the aliphatic polyester carbonate of the present invention may be carried out as it is in the apparatus used for the polymerization of the aliphatic polyester carbonate, or may be carried out using an apparatus prepared separately. Is. In the method of the present invention, since the aliphatic polyester carbonate is carried out in a molten state and the formation of a cyclic oligomer must be taken into consideration due to the existence of ring chain equilibrium, it is preferable to use an apparatus capable of obtaining a high removal rate. Therefore, the devolatilizer for the cyclic oligomer is selected from those having a high surface renewal property and capable of heating and depressurizing, but for example, a tank reactor equipped with an ordinary high-viscosity solution stirring device can be used. As the above-mentioned high-viscosity solution stirring device, a device using a lattice blade, a helical ribbon blade, a log-bone blade, etc. is exemplified.

Further, a devolatilization device known to those skilled in the art such as a horizontal stirring reaction device or a twin-screw extruder with a vent can be used, or a combination thereof can be used. The horizontal stirring reaction device has a single-axis or two-axis or more horizontal rotating shaft, and this rotating shaft is provided with a stirring blade such as a disc type, a wheel type, a paddle type, a rod type, or a window frame type. A horizontal type high-viscosity liquid treatment apparatus in which at least two or more stages are attached per rotary shaft in combination of two or more kinds, and the stirring blades lift or push the reaction solution to renew the surface of the reaction solution. The devolatilization operation using the apparatus of 1 may be a batch type or a continuous type. The "surface renewal" means that the resin liquid on the liquid surface is replaced with the resin liquid below the liquid surface.

The above-mentioned method for producing an aliphatic polyester carbonate according to the present invention is used when 1,4-butanediol and at least one aliphatic dihydroxy compound represented by the following general formula (1) are used in combination: The same applies when succinic acid and at least one of the aliphatic dicarboxylic acid compounds represented by the following general formula (2) are used in combination. _{HO-R 1 -OH (1)} R 2 OOC-R 3 -COOR 4 (2) ( wherein R ₁ and R ₃ is an alkyl group having 1 to 8 carbon atoms, which are optionally substituted by one or more identical R ₂
And R ₄ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. )

Examples of the aliphatic dihydroxy compound represented by the above general formula (1) include ethylene glycol,
Trimethylene glycol, tetramethylene glycol,
Pentanediol, hexamethylene glycol, propylene glycol, neopentyl glycol and the like are exemplified.

Examples of the aliphatic dicarboxylic acid compound represented by the above general formula (2) include oxalic acid, malonic acid, glutaric acid, adipic acid, azelaic acid, diglycolic acid, sebacic acid and alkyl esters thereof. Etc. are illustrated.

In the present invention, when at least one of the compounds represented by the above general formulas (1) and (2) is used in combination, the amounts of 1,4-butanediol and succinic acid are each 60 mol% or more. It is desirable from the viewpoint of the physical properties of the obtained polymer.

As the catalyst used in the present invention, a zirconium compound or a hafnium compound and Y, La, Z are used.
By using a composite catalyst composed of a combination with at least one selected from n and Sn, the total amount of the catalyst is smaller and a sufficient reaction rate can be obtained as compared with the case of using the zirconium compound or the hafnium compound alone. As a catalyst
Preferred forms of the compound include various fatty acid salts, hydroxides, alcoholates, phenolates, acetylacetonates and the like.

Examples of zirconium compounds and hafnium compounds are zirconium acetylacetonate, acetylacetate zirconyl, zirconium tetraethoxide, zirconium tetraisopropoxide, zirconium tetranormal butoxide, zirconium tetratert-butoxide, zirconyl chloride, zirconium chloride, zirconium sulfate. , Zirconium oxyacetate, zirconium octoate, zirconium oxystearate, hafnium acetylacetonate, hafnium tetrabutoxide, hafnium tetraisopropoxide and the like, but zirconium acetylacetonate, hafnium acetylacetonate is particularly preferably used. .

The compounds of Y, La, Zn and Sn include
Yttrium acetate, yttrium naphthenate, yttrium tris (acetylacetonato), lanthanum acetate,
Zinc acetate, zinc acetylacetonate, zinc benzoate,
Examples include zinc stearate, zinc oxide, zinc phosphate, tin oxalate, tin acetylacetonate, dibutyltin laurate, dibutyltin oxide, and tin chloride, but zinc acetylacetonate, zinc acetate, and dibutyltin oxide are particularly preferable. Used.

The catalyst is added in the above-mentioned first step in which the catalyst is used in the above combination from the beginning, and in the first step, a zirconium compound or a hafnium compound is used, and the above-mentioned second step is used. Then, Y, La, Z
There is a method of adding and reacting at least one selected from n and Sn compounds, but either method may be used. It is desired that the amount of catalyst is as small as possible, and usually the raw material (reaction) mixture 1
5 × 10 ⁻⁵ to 1 part by weight, preferably 1 × 10 ⁻⁴ to 1 × 10 ⁻² parts by weight, relative to 00 parts by weight, are used.

According to the present invention, the cyclic oligomer concentration is 0.6% by weight or less and the weight average molecular weight (Mw) is simple.
Not only can 30,000 or more aliphatic polyester carbonates be produced, but the degree of polymerization can be adjusted over a wide range, and the weight average molecular weight can be adjusted by only changing a part of the reaction conditions such as reaction time, temperature and catalyst amount. (Mw) 30000-
It is possible to appropriately produce aliphatic polyester carbonates up to around 350,000 depending on the application. However, in consideration of moldability and the like, Mw is 100,000 to
Those in the range of 250,000 are actually used.

When the biodegradable aliphatic polyester carbonate produced by the method of the present invention is used, auxiliary additives such as stabilizers, antioxidants and inorganic fillers can be blended, and according to a conventionally known method. It can be formed into various shapes such as films, sheets, foams and filaments.

[0033]

EXAMPLES The present invention will be described in more detail with reference to examples.

In this example, the molecular weights of the polyester oligomer and polyester carbonate were GPC (GPC, Sy, manufactured by Showa Denko KK) using chloroform as a solvent.
styrene equivalent Mw, Mn
Was measured as. The carbonate bond content is NM
R (Nippon Denshi Co., Ltd. NMR, EX-270) was used, and the ratio (mol%) of the carbonate unit to the total of the dicarboxylic acid ester unit and the carbonate unit was measured by ¹³ CNMR. The hydroxyl value and acid value are J
It was quantified according to IS-K1557. The amount of cyclic oligomer in the polymer was analyzed by gas chromatography (Shimadzu Corporation GC14B) after reprecipitation of a solution of the polymer in dichloromethane with methanol and concentrating the mother liquor from which the polymer was separated. The haze of the film was measured by a color difference meter (1001DP manufactured by Nippon Denshoku Industries Co., Ltd.).

Synthesis Example In a 50-liter first reactor equipped with a stirrer, a fractionating condenser, a thermometer, and a gas introduction tube, succinic acid 18.74 k was added.
g (158.7 mol), 1,4-butanediol 21.
43 kg (237.8 mol), zirconium acetylacetonate 745 mg and zinc acetylacetonate 1.50 g were charged, and the temperature was 150 to 22 under a nitrogen atmosphere.
The reaction was carried out at 0 ° C. for 2 hours to distill off water. Continued 150
Aging was performed at a reduced pressure of -80 mmHg for 3 hours to allow the dehydration reaction to proceed. Furthermore, finally, the degree of pressure reduction was gradually increased to 2 mmHg or less, water and 1,4-butanediol were further distilled off, and the reaction was stopped when the total amount of distillation reached 10.40 kg. . The total reaction time was 7.0 hours. The number average molecular weight of the obtained oligomer was 170.
0, the terminal hydroxyl value was 106 KOHmg / g, and the acid value was 0.59 KOHmg / g.

Next, 24.0 kg of the obtained oligomer was charged into a 50-liter second reactor equipped with a stirrer, a fractionating condenser, a thermometer, and a gas introduction tube, and 4.86 kg of diphenyl carbonate was added. Temperature 210-220 ℃
Finally, the pressure was reduced to 1 mmHg, and the reaction was carried out for 5 hours while distilling phenol off. The reduced pressure was released with nitrogen, 300 g of a polyester carbonate masterbatch containing 0.7 g of polyphosphoric acid was added, and after mixing with stirring, the mixture was taken out in a strand form and pelletized. The obtained high molecular weight product was not colored and had a weight average molecular weight (M
w) was 200,000, and it had 14.3% of carbonate bonds as a polycarbonate component by ¹³ CNMR measurement. In addition, the cyclic dimer is 0.91 in the resin.
% By weight, and 200 ppm of phenol was contained. However, diphenyl carbonate could not be detected.

Example 1 1.5 kg of the pellet obtained in the synthesis example was charged into an 8 liter tank reactor equipped with a stirrer with a helical ribbon blade and heated and melted. Temperature 230 ℃, Decompression degree 0.9mmH
The devolatilization operation was performed for 1 hour while stirring at 30 g with a stirring speed of 30 rpm. After devolatilization was completed, the product was taken out from the bottom of the reactor in a strand shape at a temperature of 220 ° C., solidified by cooling with water and then pelletized. Weight average molecular weight (M
w) was 205,000. The amount of cyclic dimer in the obtained pellet was reduced to 0.53% by weight. Also,
No phenol was detected. The pellets obtained 1.
2 kg was extruded from a T-die with a die width of 20 cm and a die lip of 0.7 mm at a molding temperature of 190 ° C., and a thickness of 0.05 m.
The film was molded into a film of m, the appearance characteristics of the film were visually observed, and the haze was measured. Also, from molding 1
After two weeks, two weeks, and four weeks, the appearance characteristics and the haze were similarly measured, and the time-dependent change of the surface deposits was followed, but no change in the appearance was observed. The results are shown in Table 1.

Example 2 1.5 kg of the pellet obtained in the synthesis example was placed in an 8 liter tank reactor equipped with a stirrer with a helical ribbon blade and heated and melted. Temperature 230 ℃, Decompression degree 0.6mmH
The devolatilization operation was performed for 2 hours while stirring at 45 g with a stirring speed of 45 rpm. After devolatilization was completed, the product was taken out from the bottom of the reactor in a strand shape at a temperature of 220 ° C., solidified by cooling with water and then pelletized. Weight average molecular weight (M
w) was 209,000. The amount of cyclic dimer in the obtained pellet was reduced to 0.25% by weight. Also,
No phenol was detected. Further, similarly to Example 1, the film was formed by the T-die method, and the appearance characteristics were observed and the haze was measured. No change in appearance and no change in haze of the film were observed. The results are shown in Table 1.

Comparative Example 1 2 kg of the pellet obtained in the synthesis example was extruded as it was from a T-die having a die width of 20 cm and a die lip of 0.7 mm at a molding temperature of 190 ° C. without being devolatilized, and a thickness of 0.05 was obtained.
It was formed into a film of mm. The appearance characteristics and the haze were measured in the same manner as in Example 1. After one week, precipitates became visible on the surface of the film, and haze also increased. The results are shown in Table 1.

Comparative Example 2 13 kg of pellets obtained in the synthesis example were extruded at a temperature of 23 using a twin-screw extruder with a vent (screw diameter 35 mmφ).
Devolatilization extrusion was performed under reduced pressure of 0 to 2 mmHg at 0 ° C. to form pellets. Weight average molecular weight (M
w) was 202000. The amount of cyclic dimer in the obtained pellet was reduced to 0.65% by weight, and the amount of phenol contained was 20 ppm. Further, similarly to Example 1, the film was formed by the T-die method, and the appearance characteristics were observed and the haze was measured. The results are shown in Table 1.

Comparative Example 3 A pellet-form phosphorus compound was prepared in the same manner as in the above Synthesis Example except that the polyester carbonate masterbatch containing polyphosphoric acid was not added at the end of the reaction in the second reactor. A polyester carbonate without addition was obtained. The resulting high molecular weight has a weight average molecular weight by measurement of GPC (Mw) is 195000, ¹³
1 as a polycarbonate component by CNMR measurement
It had 3.9% carbonate bonds. The cyclic dimer content in the resin was 0.88% by weight, and the phenol content was 300 ppm. However, diphenyl carbonate was not detected.

The obtained pellets were placed in an 8 liter tank reactor equipped with the same agitator with helical ribbon blades as in Example 1, and heated and melted. The mixture was stirred at a temperature of 230 ° C. and a reduced pressure of 0.8 mmHg at a speed of 30 rpm. 20
After a minute, the stirring torque started to increase, and after 1 hour, the stirring became impossible, and it was difficult to take it out from the bottom of the reactor and pelletize it. The molecular weight of the resin extracted from the upper portion of the reactor was 390000 in Mw. Further, the cyclic dimer in the resin was 0.95% by weight, and the content of the oligomer was increased.

5.0 g of each of the pellets obtained in Synthesis Example and Comparative Example 3 was placed in a glass bottle and heated at 220 ° C. for 30 minutes.
It was melted and heated for a minute. As a result, each molecular weight is Mw
Then, 197,000 and 162000 were obtained, and those without addition of the phosphorus-based compound had remarkably reduced molecular weight, and those with addition of phosphorus compounds had a small reduction rate of the molecular weight.

[0044]

[Table 1]

[0045]

INDUSTRIAL APPLICABILITY The biodegradable aliphatic polyester carbonate of the present invention has an excellent appearance after molding, and is suitable for obtaining a molded product such as a film, sheet, foam or fiber. Further, the fluidity, injection moldability, and thermal stability are also excellent, and the obtained molded product has high mechanical strength and can be used as a substitute for conventional general-purpose resins. It shows high biodegradability even in soil or activated sludge treatment,
It can be widely used for packaging materials and molded products that require biodegradability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayoshi Mine 22 Wadai, Tsukuba City, Ibaraki Prefecture Mitsubishi Gas Chemical Co., Ltd.

Claims (7)

[Claims] 1. An aliphatic polyester oligomer is obtained by reacting an aliphatic dihydroxy compound having 1,4-butanediol as a main component with an aliphatic dicarboxylic acid compound having succinic acid as a main component, and the oligomer and diphenyl carbonate. With a weight average molecular weight of 10
A biodegradable aliphatic polyester carbonate having a content of cyclic oligomer of 0000 or more and 0.6% by weight or less. 2. The aliphatic polyester carbonate according to claim 1, wherein the cyclic oligomer is a cyclic dimer mainly composed of 1,4-butanediol and succinic acid. 3. The aliphatic polyester carbonate according to claim 1, wherein the aliphatic polyester oligomer has a number average molecular weight of 10,000 or less. 4. An aliphatic polyester oligomer is obtained by reacting an aliphatic dihydroxy compound having 1,4-butanediol as a main component with an aliphatic dicarboxylic acid compound having succinic acid as a main component, and the oligomer and diphenyl carbonate. In obtaining the aliphatic polyester carbonate by reacting with, after the completion of the polymerization reaction, a phosphorus compound is added and mixed, and then the temperature is 130 to 300 ° C. and the degree of vacuum is 10 m.
A method for producing a biodegradable aliphatic polyester carbonate, characterized by being devolatilized under a condition of mHg or less so that the cyclic oligomer content is 0.6% by weight or less. 5. The method according to claim 4, wherein the phosphorus compound is a compound such as phosphoric acid, polyphosphoric acid, phosphorous acid and their esters. 6. 1,4-butanediol and general formula (1)
Wherein at least one kind of the aliphatic dihydroxy compound represented by the formula (1) is used in combination, and succinic acid and at least one kind of the aliphatic dicarboxylic acid compound represented by the general formula (2) are used together. 4. The manufacturing method according to 4. HO-R ₁ -OH (1) R ₂ OOC-R ₃ -COOR ₄ (2) (In the formula, R ₁ and R ₃ are alkyl groups having 1 to 8 carbon atoms, and even if they are the same. May be different R ₂
And R ₄ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ) 7. The method according to claim 6, wherein each of 1,4-butanediol and succinic acid is at least 60% (mol).