JP3501188B2 - Method for producing biodegradable aliphatic polyester carbonate - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a biodegradable aliphatic polyester carbonate which is free from surface deposits when formed into fibers, films, sheets and other molded articles and has excellent appearance characteristics and thermal stability. It relates to a manufacturing method. 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, and as a fertilizer coating material. It is useful 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 biodegradable polymer here means, for example,
When the molded product is left in the soil or water, it means that the polymer decomposes and disappears by the action of microorganisms. Classified as a biodegradable polymer is an aliphatic polyester carbonate produced by a ring-opening polymerization method using a cyclic monomer. These have a hydroxycarboxylic acid unit and an aliphatic carbonate unit as its constituent elements,
Some of them are biocompatible and used in the medical field, but their use as molded bodies is limited because they are hydrolyzable.

On the other hand, although it is known to produce a polyester carbonate from an aliphatic dicarboxylic acid, an aliphatic diol and a diaryl carbonate, an aliphatic polyester carbonate containing the aliphatic dicarboxylic acid and the aliphatic diol as a constituent is generally used. Although it has been proposed to be used as a material for polymer alloys with adhesives, sealing agents, coating agents, and other resins, its main application is liquid. It has been used as a low molecular weight material for urethane as a raw material, and has not yet been found to be practically used after being processed into a molded product such as a film, sheet or fiber which requires a high molecular weight.

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 having good melt moldability, biodegradability, etc., but as a result of further research on physical properties, uses, etc. It became clear that the appearance characteristics were deteriorated by the precipitates.

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, it is known that the cyclic trimer in PET can be reduced to about 0.3% by weight.

Aliphatic polyester carbonates obtained by melt polycondensation of aliphatic polyester oligomers with diaryl carbonates are known polymers 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 Japanese Patent Laid-Open No. 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 is hard to say that it is not enough. Therefore, it was necessary to develop a new method for reducing cyclic oligomers.

[0008]

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. Another object of the present invention is to provide a method for producing a biodegradable aliphatic polyester carbonate resin which has no problems in post-processing and application fields.

[0009]

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
(A molecularly reacted one) as a main component, a phosphorus-based compound is added to and mixed with a polymerization reaction product to obtain a granular aliphatic polyester carbonate, and the granular aliphatic polyester carbonate, an organic solvent and / or
It was also found that they can be removed from the resin by contact with water. 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. Biodegradation, characterized in that a granular aliphatic polyester carbonate is obtained after adding and mixing a phosphorus compound to the reaction product with carbonate, and the granular aliphatic polyester carbonate is contacted with an organic solvent and / or water. It is a method for producing a polyaliphatic polyester carbonate.

Further, the present invention provides an aliphatic polyester oligomer comprising an aliphatic dihydroxy compound having 1,4-butanediol as a main component and an aliphatic dicarboxylic acid compound having succinic acid as a main component, and the oligomer. A phosphorus-based compound is added to and mixed with a reaction product with diphenyl carbonate to obtain a granular aliphatic polyester carbonate, and the granular aliphatic polyester carbonate is brought into contact with an organic solvent and / or water to give mainly 1 The method for producing a biodegradable aliphatic polyester carbonate is characterized in that the content of the cyclic oligomer comprising 4,4-butanediol and succinic acid is 0.6% by weight or less.

In the production of the aliphatic polyester carbonate according to the present invention, an aliphatic polyester oligomer is obtained from 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, a second step of reacting the aliphatic polyester oligomer obtained in the first step with diphenyl carbonate, and a third step of removing the cyclic oligomer from the obtained aliphatic polyester carbonate. 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.
It is a step of producing a polyester oligomer having a number average molecular weight of 500 to 10000 at 250 ° C., preferably 150 to 220 ° C., while removing water by-produced by the reaction and an excess of 1,4-butanediol. 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 reaction is carried out is selected so that the above object is achieved, and may be reduced to 300 mmHg or less for the purpose of promoting the reaction.

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 conditions of 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 reduced pressure, the reaction time is shortened and 1,4-
Although the amount of butanediol remaining can be reduced, 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 the removal of water mainly produced by condensation, which is carried out at normal pressure. The second stage is the completion of the dehydration condensation reaction,
That is, in the aging step for reducing the acid value, 200 to 80
Water and a small amount of 1,4-butanediol are distilled off at a reduced pressure of about mmHg. The third stage is a step of increasing the molecular weight by distilling off excess 1,4-butanediol, and finally the pressure is reduced to 5 mmHg or less. 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 to 200
A range of KOHmg / 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 49 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 resulting polymer may be colored,
High temperatures exceeding the above range are not preferred. 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.

After adding and mixing a phosphorus compound to the obtained aliphatic polyester carbonate in a nitrogen atmosphere,
It can be extracted from the reaction tank in a molten state into a strand, cooled and solidified, and then granulated with a pelletizer. The addition of phosphorus compounds has an excellent stabilizing effect. That is, the addition of the phosphorus-based compound has an effect of suppressing a decrease in molecular weight due to hydrolysis of the polymer or the like in the third step described later. Further, it is effective in preventing the decrease of the molecular weight of the polymer in the molten state and suppressing the regeneration of the cyclic oligomer. As the phosphorus compound, phosphoric acid, polyphosphoric acid,
Phosphorous acid and its ester are illustrated. The amount of addition is 0.3 to 10 times, preferably 0.5 to 5 times the molar amount of the catalyst used in the first and second steps.

The granular aliphatic polyester carbonate referred to in the present invention is not limited to a granular one in a strict sense, and includes powdery and flaky ones.
The granular aliphatic polyester carbonate obtained in the second step is usually in the form of pellets and contains 1 to 3% by weight of cyclic oligomer. In addition, about 300 ppm of by-produced phenol and less than 20 ppm of 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 granular aliphatic polyester carbonate obtained in the polymerization step. In this step, the above-mentioned granular aliphatic polyester carbonate containing a cyclic oligomer is introduced together with an organic solvent and / or water into a processing container equipped with a discharge device. The processing container used here is preferably one equipped with, for example, a temperature control device for maintaining the processing temperature, a circulation mechanism for circulating the solvent, or an overflow device for introducing the solvent from the bottom and discharging it from the top, but it is necessary. For example, a stirring mechanism, a solid-liquid separation mechanism, a drying mechanism and the like may be provided.

As the organic solvent to be introduced, various kinds can be used as long as the cyclic oligomer can be extracted from the granular aliphatic polyester carbonate. A solvent is preferably used. For example, alcohols such as methanol, ethanol and propanol, ketones such as acetone, methyl ethyl ketone and diisobutyl ketone, ethers such as diethyl ether, dioxane and tetrahydrofuran, aliphatic and aromatic compounds such as hexane, heptane, benzene, toluene and xylene. Examples thereof include group hydrocarbons, esters such as methyl acetate and ethyl acetate, and water containing or not containing the above solvent. In addition to these, a mixed solvent of a good solvent that dissolves an aliphatic polyester carbonate such as dichloromethane and chloroform and the above poor solvent can also be used. Of these organic solvents, methanol and acetone are particularly preferable. Further, the amount of the organic solvent introduced into the above-mentioned processing container may be any amount as long as it can sufficiently contact the granular aliphatic polyester carbonate containing impurities. Specifically, the weight ratio to the granular aliphatic polyester carbonate to be treated is 0.5 to 2
The amount is 0 times, preferably 1 to 5 times.

The conditions for contacting the above-mentioned granular aliphatic polyester carbonate with the organic solvent and / or water are appropriately selected depending on the type of solvent and particle size, but a temperature below the melting point of the polyester carbonate is preferable, and usually 20 to 110. C. or the temperature below the boiling point of the solvent, and the extraction time are preferably 0.1 to 10 hours. By such extraction treatment, the content of the cyclic oligomer in the aliphatic polyester carbonate is preferably 0.6% by weight or less. At the same time, the amount of phenol is 20ppm
Hereinafter, the amount of diphenyl carbonate will be 10 ppm or less. When the cyclic oligomer concentration exceeds 0.6% 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, which is not preferable. Further, when the amount of phenol is 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, the granular aliphatic polyester carbonate is separated from the organic solvent and / or water after the extraction treatment is carried out in the treatment container and dried. The solid-liquid separation method and the drying method are not particularly limited and may be appropriately selected. The device used for solid-liquid separation may be, for example, one having a filter plate installed near the bottom of the extraction treatment container, or may be a filtration device independent of the extraction container. The drying method may be natural drying, but it is usually dried under heating and / or under reduced pressure. In the present invention, 1,4-
Since it is a polyester carbonate containing butanediol and succinic acid as main components, the temperature of the drying treatment is 80 to 11
The temperature is preferably 0 ° C. Alternatively, it can be heated and dried under aeration of an inert gas such as nitrogen, and it is also effective to heat and dry while stirring with a stirring blade or the like. Here, the above-mentioned drying mechanism is usually constituted by a heating means, and auxiliary stirring means and decompression means are additionally provided if necessary, and may be provided in the extraction container or may be a known independent drying mechanism.

For the production of the aliphatic polyester carbonate used in the present invention, 1,4-butanediol and ethylene glycol, trimethylene glycol, tetramethylene glycol, pentanediol, hexamethylene glycol, propylene glycol, neopentyl glycol and the like are used. In combination with an aliphatic dihydroxy compound, succinic acid and oxalic acid, malonic acid, glutaric acid, adipic acid,
It is also possible to use an aliphatic dicarboxylic acid compound such as azelaic acid, diglycolic acid or sebacic acid together. When an aliphatic dihydroxy compound and an aliphatic dicarboxylic acid compound are used in combination, the amounts of 1,4-butanediol and succinic acid are preferably 60 mol% or more from the viewpoint of the physical properties of the obtained polymer.

The catalyst used in the present invention is selected from the transesterification catalysts, and a zirconium compound or a hafnium compound and at least one selected from Y, La, Zn and Sn are combined to form a composite catalyst, A sufficient reaction rate can be obtained with a smaller total amount of catalyst than when using a zirconium compound or a hafnium compound alone. As the catalyst, various preferable compound forms include 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 and hafnium acetylacetonate are 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, zinc stearate, zinc oxide. , Zinc phosphate, tin oxalate, tin acetylacetonate, dibutyltin laurate, dibutyltin oxide, tin chloride, and the like. Among them, zinc acetylacetonate, zinc acetate, dibutyltin oxide are particularly preferably 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 in the above-mentioned second step, the catalyst is added. Y, La, Zn,
There is a method in which at least one selected from Sn compounds is added and reacted, but either method may be used. It is desired that the amount of the 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 2 × 10 ⁻² parts by weight, relative to 00 parts by weight, are used.

According to the present invention, the cyclic oligomer content is 0.6% by weight or less and the weight average molecular weight (M
w) Not only is it possible to produce 30,000 or more aliphatic polyester carbonates, but it is also possible to control the degree of polymerization in a wide range, and by only changing a part of the reaction conditions such as reaction time, temperature and catalyst amount, Weight average molecular weight (Mw) 30
The aliphatic polyester carbonate of about 000 to 350,000 can be appropriately produced depending on the application. However, considering molding processability, Mw is 100,000.
Those in the range of up to 250,000 are actually used.

When the biodegradable aliphatic polyester carbonate produced by the method of the present invention is used, conventional auxiliary additives such as stabilizers, antioxidants and inorganic fillers can be added, and they are conventionally known. According to the method, it can be formed into various shapes such as a film, a sheet, a foam and a filament.

[0031]

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, Sys, manufactured by Showa Denko KK) using chloroform as a solvent.
tem-11) was used and it measured as Mw and Mn of styrene conversion. The carbonate bond content is NMR
(Nippon Denshi Co., Ltd. NMR, EX-270)
^It was measured by ¹³ CNMR as the ratio (mol%) of carbonate units to the total of dicarboxylic acid ester units and carbonate units. Hydroxyl value and acid value are JI
It was quantified according to S-K1557. The cyclic oligomer in the polymer was quantified by reprecipitating a solution of polyestercarbonate in dichloromethane with methanol and separating the polymer by gas chromatography (Shimadzu GC
14B). The haze (haze value of the film) was measured by a color difference meter (1001DP manufactured by Nippon Denshoku Industries Co., Ltd.).

Example 1 In a 50-liter first reactor equipped with a stirrer, a fractionating condenser, a thermometer, and a gas introduction tube, 18.74 k of succinic acid 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. Then, the mixture was aged at a reduced pressure of 150 to 80 mmHg for 3 hours to allow the dehydration reaction to proceed. Finally, the pressure reduction degree was gradually increased to a pressure reduction degree of 2 mmHg or less to further distill water and 1,4-butanediol, 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 1700, the terminal hydroxyl value was 106 KOHmg / g, and the acid value was 0.
It was 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 the mixture was extruded and pelletized after mixing. Average pellet size is 3m long
m and diameter 2 mm (referred to as pellet a). The obtained high molecular weight product was not colored, had a weight average molecular weight (Mw) of 213,000 as measured by GPC, and had 14.3% carbonate bonds as a polycarbonate component by ¹³ CNMR measurement. Further, the resin contained 0.92% by weight of cyclic dimer and 300 ppm of phenol, and diphenyl carbonate was not detected.

Subsequently, 20 kg of the obtained polyester carbonate pellets were charged into a 50-liter extraction tank, and the temperature was adjusted to 5 by a solvent inlet with a mesh filter provided at the bottom of the extraction tank and an overflow pipe provided at the top of the extraction tank.
Under the condition of 0 ° C., 50 kg of acetone was circulated from the external storage tank to the inside of the extraction tank at a rate of 10 l / min for 5 hours. After returning the acetone to the storage tank, the polyester carbonate was discharged from the discharge valve provided at the bottom of the extraction tank and dried at 90 ° C. Cyclic 2 in dried polyester carbonate
The amount of monomers was reduced to 0.05% by weight, and phenol was not detected. The molecular weight is 217,000 in Mw.
Met. Forming temperature 1 using the obtained dry pellets
T- with a die width of 20 cm and a die lip of 0.7 mm at 90 ° C
It was extruded from a die and formed into a film having a thickness of 0.05 mm. The appearance characteristics (visual observation) and haze of the obtained film were measured. Also, 1 week, 2 weeks, and 4 weeks after the molding, the appearance characteristics and the haze were similarly measured, and the time change of the surface precipitate was followed, but the appearance of the film did not change, and the haze was not changed. No change was observed. The results are shown in Table 1.

Comparative Example 1 A film was produced from the polyester carbonate (pellet a) obtained in Example 1 in the same manner as in Example 1 except that the extraction treatment was omitted. Further, the appearance characteristics were observed and the haze was measured in the same manner as in Example 1. White precipitates were observed on the surface 2 weeks after the film was formed. The results are shown in Table 1.

Example 2 Using the polyester carbonate (pellet a) obtained in Example 1 except that the extraction temperature was 35 ° C., the same extraction operation as in Example 1 was performed. The amount of cyclic dimer in the polyester carbonate after drying was reduced to 0.38% by weight, and phenol was not detected. The molecular weight of the polyester carbonate was 215,000 in Mw. A film was produced in the same manner as in Example 1 using the obtained dry pellets. Further, the appearance characteristics were observed and the haze was measured in the same manner as in Example 1. The results are shown in Table 1.
It was shown to.

Example 3 Methanol was used instead of acetone and the extraction temperature was 60 ° C.
The same extraction operation as in Example 1 was performed using the polyester carbonate (pellet a) obtained in Example 1 except that The amount of cyclic dimer in the polyester carbonate after drying was reduced to 0.12% by weight, and phenol was not detected. Moreover, the molecular weight of the polyester carbonate was 210000 in Mw. A film was produced in the same manner as in Example 1 using the obtained dry pellets. Further, the appearance characteristics were observed and the haze was measured in the same manner as in Example 1. The results are shown in Table 1.

Example 4 The polyester carbonate (pellet a) obtained in Example 1 was used except that water was used instead of acetone, the extraction temperature was 80 ° C., and the extraction operation was 8 hours.
The same extraction operation was performed. The amount of cyclic dimer in the polyester carbonate after drying was reduced to 0.56% by weight, and phenol was not detected. Moreover, the molecular weight of the polyester carbonate was 210000 in Mw. A film was produced in the same manner as in Example 1 using the obtained dry pellets. Further, the appearance characteristics were observed and the haze was measured in the same manner as in Example 1. After 4 weeks, the film surface was slightly blurred. The results are shown in Table 1.

Comparative Example 2 Pellets were repeatedly obtained in the same manner as in Example 1 except that the master batch of polyphosphoric acid was not added (referred to as pellet b). The obtained high molecular weight product had a weight average molecular weight (Mw) of 210000 as measured by GPC, and ¹³ CNMR
According to the measurement, it had 14.1% of carbonate bonds as a polycarbonate component. Further, the resin contained 0.89% by weight of cyclic dimer and 280 ppm of phenol, and diphenyl carbonate was not detected. The obtained pellet b was extracted with acetone under the same conditions as in Example 1. The cyclic dimer in the dry pellets was reduced to 0.06% by weight, and phenol was not detected, but the weight average molecular weight (Mw) of the dry pellets was 200,000, and it was found that the decrease in the molecular weight was large.

Further, 5.0 g of each of the pellets a and pellets b was placed in a glass bottle, and the pellets were heated at 220 ° C. for 30 minutes.
It was heated and melted for a minute. As a result, the weight average molecular weight (Mw)
Was 209000 and 168000, respectively, and it was found that the decrease in the molecular weight of the pellet b to which the phosphorus compound was not added was large. Further, the contents of the cyclic dimer in each resin were 0.92 and 0.96% by weight, respectively, and the content of the cyclic dimer in the pellet b to which the phosphorus compound was not added was rather increased. It was

[0042]

[Table 1]

[0043]

INDUSTRIAL APPLICABILITY The biodegradable aliphatic polyester carbonate obtained by the present invention has an excellent appearance after molding, and is therefore suitable for obtaining molded articles such as films, sheets, foams and fibers. Further, the fluidity, injection moldability, and thermal stability are excellent, and the resulting molded product has high mechanical strength and can be used as a substitute for conventional general-purpose resins. Further, it exhibits high biodegradability in the environment, and can be widely used for packaging materials and molded products which require biodegradability.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-53695 (JP, A) JP-A-7-53693 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 63/00-63/91 C08L 67/00 C08L 69/00

Claims (4)

(57) [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. Biodegradable, characterized in that a granular aliphatic polyester carbonate is obtained after adding and mixing a phosphorus compound to the reaction product with, and the granular aliphatic polyester carbonate is contacted with an organic solvent and / or water. Method for producing aliphatic polyester carbonate. 2. The production of an aliphatic polyester carbonate according to claim 1, wherein the content of the cyclic oligomer mainly consisting of 1,4-butanediol and succinic acid is 0.6% by weight or less. Method. 3. The method for producing an aliphatic polyester carbonate according to claim 1, wherein the phosphorus-based compound is phosphoric acid, polyphosphoric acid, phosphorous acid and esters thereof. 4. The method for producing an aliphatic polyester carbonate according to claim 1, wherein the weight average molecular weight of the granular aliphatic polyester carbonate is 100,000 or more.