JP3274369B2 - Method for producing aliphatic block copolyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing an aliphatic block copolyester having an aliphatic diol, an aliphatic dicarboxylic acid and lactic acid as monomer units. Aliphatic polyesters are relatively easily hydrolyzed in the presence of water, are degraded by microorganisms, and are also hydrolyzed and absorbed in vivo, making them useful as substitutes for medical materials and general-purpose resins. As a degradable polymer, an aliphatic copolyester has attracted attention as a biodegradable polymer that imparts properties that cannot be obtained with conventional aliphatic homopolyesters.

[0002]

2. Description of the Related Art Polylactic acid has mechanical properties close to that of polystyrene and has biodegradability. Since it is an earth-friendly resin, it will be used in the future as a substitute for polystyrene that does not have biodegradability. It is greatly expected. However, polylactic acid is hard and brittle as compared with polyethylene-based resins, and it has been considered difficult to substitute polyethylene-based resins.

[0003] In order to develop a new resin having the same level of mechanical strength as a polyethylene resin and having biodegradability, research and development of various biodegradable copolyesters based on polylactic acid have been promoted. I have. For example, JP-A-8-
No. 3,296, JP-A-7-228675,
Aliphatic diol, aliphatic dicarboxylic acid and lactic acid are copolymerized from monomers to produce aliphatic random copolyester, and attempt to develop biodegradable resin with the same level of mechanical strength as polyethylene resin ing.
However, the method described above has a problem that the aliphatic diol distills out of the system together with the distilling water, and the constitutional ratio of the monomer unit changes, so that the mechanical properties tend to fluctuate. Therefore, in order to produce a resin having the intended mechanical properties, it is necessary to appropriately change various polymerization conditions such as the charge composition ratio of the raw material monomer, temperature and time, and the degree of reduced pressure. It was inappropriate.

As a method for producing a biodegradable copolyester based on a polylactic acid skeleton, besides the above, JP-A-7-53685 and JP-A-7-30005
No. 20, JP-A-7-173266 are known. In these methods, an aliphatic block copolyester is produced by ring-opening polymerization and transesterification of an aliphatic polyester composed of an aliphatic diol and an aliphatic dicarboxylic acid with lactide. Since block copolymers have different physical properties depending on the size of the block units, in these methods, it is possible to produce block copolyesters having various mechanical properties under the same monomer composition and the same polymerization conditions. In order to achieve the object, there is a need for a technique for freely producing polymers having different molecular weights of aliphatic polyesters, which are aliphatic diols and aliphatic dicarboxylic acids, which are one of the starting materials. In addition, a large amount of labor is required to obtain lactide, which is another starting material used in these methods, and there is a problem that it is very complicated and expensive when manufactured industrially. I was

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an industrially advantageous method for freely producing aliphatic copolyesters having various mechanical properties which cannot be obtained with conventional polylactic acid. That is.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to produce an aliphatic block copolyester having mechanical properties which cannot be obtained with conventional polylactic acid by an industrially advantageous method. The oligomer is subjected to dehydration polycondensation, and water at 98% or more of the total amount of distilled water is distilled off. At any point, an aliphatic polyester composed of an aliphatic diol and an aliphatic dicarboxylic acid is added to distill the aliphatic diol. Can be suppressed, and even if a single aliphatic polyester is used as a starting material, the tensile yield strength is 100 to 400 kg /
It has been found that aliphatic copolyesters having arbitrary mechanical properties in the range of 100 to 1000% in cm ² and tensile elongation at break can be freely produced, and the present invention has been completed.

That is, the present invention is as follows. Lactic acid or an oligomer thereof is subjected to a dehydration polycondensation reaction in an organic solvent in the presence of a catalyst, and at any point when 98% or more of the total distilled water is distilled off, a weight average of aliphatic diol and aliphatic dicarboxylic acid is obtained. A method for producing an aliphatic block copolyester, comprising adding an aliphatic polyester having a molecular weight of 3,000 or more and performing a dehydration polycondensation reaction. Lactic acid or an oligomer thereof is subjected to a dehydration polycondensation reaction in an organic solvent in the presence of a catalyst, and at any point when 98% or more of the total distilled water is distilled off, a weight average of aliphatic diol and aliphatic dicarboxylic acid is obtained. An aliphatic block copolyester having a tensile yield strength of 100 to 400 kg / cm ² and a tensile elongation at break of 100 to 1000%, characterized by adding an aliphatic polyester having a molecular weight of 3,000 or more and performing a dehydration polycondensation reaction. Production method. Lactic acid or an oligomer thereof is subjected to a dehydration polycondensation reaction in an organic solvent in the presence of a catalyst, and at any point when 98% or more of the total distilled water is distilled off, a weight average of aliphatic diol and aliphatic dicarboxylic acid is obtained. A method for producing an aliphatic block copolyester having two or more melting points, comprising adding an aliphatic polyester having a molecular weight of 3,000 or more to carry out a dehydration polycondensation reaction. An aliphatic block copolyester obtained by the above production method.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Lactic acid or an oligomer thereof used in the present invention may be a D-form or an L-form alone, or a mixture of D-form and L-form, that is, a racemic form. Further, a mixture composed of a monomer, a monomer, a trimer and water, such as commercially available lactic acid, can be used without any problem. Further, aldehydes, carboxylic acids, alcohols, hydroxycarboxylic acids, and esters, such as formaldehyde, acetaldehyde, formic acid, acetic acid, pyruvic acid, acrylic acid, and 2-methoxypropionic acid that do not interfere with obtaining the target molecular weight. , 2-
Hydroxy-n-butyric acid, 2-hydroxy-3-methylbutyric acid, fumaric acid, glycolic acid, 3-hydroxybutyric acid,
-Hydroxybutyric acid, 3-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid, methanol, ethanol, 2,3-butanediol, 1,2
-May contain propanediol, methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl pyruvate, ethyl pyruvate, methyl lactate and the like.

Examples of the catalyst used in the present invention include metals belonging to Groups I, II, III, IV and V of the periodic table, or salts, hydroxides and oxides thereof.

[0010] For example, metals such as zinc, tin, aluminum, magnesium, antimony, titanium and zirconium; metal oxides such as tin oxide, antimony oxide, lead oxide, aluminum oxide, magnesium oxide and titanium oxide; zinc chloride, primary chloride Metal halides such as tin, stannous bromide, antimony fluoride, zinc chloride, magnesium chloride, aluminum chloride; tin hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, Zinc hydroxide, iron hydroxide, cobalt hydroxide, nickel hydroxide, copper hydroxide, cesium hydroxide, strontium hydroxide, barium hydroxide, lithium hydroxide,
Metal hydroxides such as zirconium hydroxide; sulfates such as tin sulfate, zinc sulfate, and aluminum sulfate; magnesium carbonate;
Carbonates such as zinc carbonate and calcium carbonate; organic carboxylate salts such as tin acetate, tin octoate, tin lactate, zinc acetate, aluminum acetate and iron lactate; organic acids such as tin trifluoromethanesulfonate and tin p-toluenesulfonate Sulfonates and the like.

In addition, an organic metal oxide of the above metal such as dibutyltin oxide or a metal alkoxide of the above metal such as titanium isopropoxide or an alkyl metal of the above metal such as diethyl zinc, and ion exchange such as Dowex or Amberlite Resins. In particular, in order to obtain a high molecular weight polymer, it is preferable to use metal tin and / or a divalent tin compound. The use amount thereof is preferably 0.0001 to 10% by weight of the obtained aliphatic block copolyester.

The organic solvent used in the present invention is not particularly limited, but is preferably an aromatic hydrocarbon, an ether-based aromatic hydrocarbon, or the like.

The aromatic hydrocarbons include toluene, xylene, biphenyl, naphthalene, chlorobenzene, o
-Dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, 1-chloronaphthalene and the like.

Examples of the ether aromatic hydrocarbons include alkoxybenzenes and diphenyl ethers.

The alkoxybenzenes include anisole, ethoxybenzene, propoxybenzene, butoxybenzene, pentoxybenzene, 2,4-dimethoxybenzene, 2-chloromethoxybenzene, 2-bromomethoxybenzene, 4-chloromethoxybenzene, -Bromomethoxybenzene, 2,4-dichloromethoxybenzene and the like.

The diphenyl ethers include diphenyl ether, 4,4'-dimethyldiphenyl ether,
Alkyl-substituted diphenyl ethers such as 3,3'-dimethyldiphenyl ether and 3-methyldiphenyl ether; halogen-substituted diphenyl ethers such as 4,4'-dibromodiphenyl ether and 4-methyl-4'-bromodiphenyl ether; 4-methoxydiphenyl ether and 4,4 ' -Dimethoxydiphenyl ether, 3,3
'-Dimethoxydiphenyl ether, 4-methyl-4'
And alkoxy-substituted diphenyl ethers such as -methoxydiphenyl ether; cyclic diphenyl ethers such as dibenzofuran and xanthene.

Preferred are anisole, diphenyl ether, naphthalene, o-dichlorobenzene and the like. These may be one kind or a mixture of two or more kinds, and there is no limitation.

In the present invention, as a method for carrying out a dehydration polycondensation reaction of lactic acid or an oligomer thereof in an organic solvent in the presence of a catalyst, for example, JP-A-4-337321, JP-A-6-65360 and JP-A-6-65360 -172501, JP-A-6-172502, JP-A-6-29
No. 8,913, JP-A-6-298914, JP-A-6-316149, and the like.

In the present invention, since the solution viscosity increases extremely with the increase in the degree of polymerization, the polymerization can be carried out while diluting with a solvent to lower the viscosity. The amount of the solvent can be used within a range where the polymer concentration becomes 3 to 80% by weight, preferably 3 to 70% by weight, more preferably 3 to 60% by weight, and still more preferably 3 to 50% by weight. % Is preferable. If the amount is more than 80% by weight, the viscosity when the polymer is heated and dissolved becomes extremely high, and the polymer is thermally degraded by local heating, so that it is difficult to obtain a high molecular weight aliphatic copolyester. When the amount is less than 3% by weight, there is no problem in the reaction, but the volumetric efficiency is poor and disadvantageous in productivity.

The dehydration polycondensation reaction in the method of the present invention is carried out under normal pressure and / or reduced pressure, and the reaction temperature is 80 to 200.
C., preferably at 80 to 150 C. When the reaction temperature is lower than 80 ° C., the polymer in the solution is precipitated depending on the kind of the selected solvent, and the viscosity of the organic solvent solution of the polymer becomes extremely high. When the reaction temperature is higher than 200 ° C., depolymerization is promoted, so that it becomes difficult to obtain a high molecular weight aliphatic block copolyester. When the reaction temperature is higher than 150 ° C., transesterification occurs during the dehydration polycondensation reaction, so that the mechanical properties of the resulting aliphatic copolyester are obtained by converting aliphatic diol, aliphatic dicarboxylic acid and lactic acid from monomers. The properties are close to those of an aliphatic random copolyester obtained by copolymerization, and it is difficult to produce an aliphatic copolyester having desired mechanical properties.

In the present invention, since the reaction is a dehydration polycondensation, it is necessary to use an apparatus capable of removing water generated as the reaction proceeds to the outside of the reaction system.

As a method for removing generated water, a system comprising a system having a system having a system having a system capable of treating a water-containing solvent distilled under reflux of a solvent with a desiccant and then returning it to the system or a device having a distillation separation ability is used. The mixture is allowed to react, and the mixture of the refluxing solvent and water is separated by distillation as it is to remove water, and a reflux system that returns only the dehydrated solvent to the system, and furthermore, the distilling water-containing solvent is withdrawn to the outside of the reaction system. Any method of returning the dehydrated solvent to the system can be used.

That is, as long as the solvent to be returned into the reaction system contains substantially no water, there are no restrictions on the apparatus and dehydration method.

When a drying agent is used, for example, metal sieves such as molecular sieves, ion exchange resin, diphosphorus pentoxide, calcium hydride, sodium hydride, lithium aluminum hydride; alkali metals such as sodium and lithium; Can be used. Above all, from the ease of reproduction,
Molecular sieves and ion exchange resins are preferred. As the ion exchange resin, a cation exchange resin having a sulfonic acid group or a carboxyl group as an exchange group, an anion exchange resin having a trimethylammonium group, a dimethylhydroxyethylammonium group, a dimethylamino group, or the like can be selected. You can choose any.

In the method of the present invention, a coloring inhibitor may be added to suppress coloring due to thermal deterioration during the dehydration polycondensation reaction. As the coloring inhibitor to be used, phosphorus compounds such as phosphoric acid, triphenyl phosphate, pyrophosphoric acid, phosphorous acid and triphenyl phosphite are preferred. The addition amount is 0.01 to 5% by weight based on the polymer, more preferably 0.5 to 5% by weight.
~ 2% by weight. If the amount is less than 0.01% by weight, the effect of preventing coloration is small, and if the amount is more than 5% by weight, the desired degree of polymerization cannot be obtained due to the difference in the type of the selected colorant, and economical aspects cannot be obtained. Is also not preferred.

As the aliphatic polyester composed of the aliphatic diol and the aliphatic dicarboxylic acid used in the present invention, those obtained by any conventionally known method can be used. That is, for example, aliphatic polyesters obtained by a normal polyester production method of performing polymerization by a glycol removal reaction, and the aliphatic polyesters described in JP-A-6-271656 and JP-A-7-304839. Aliphatic polyesters obtained by increasing the molecular weight of polyester with a binder, aliphatic polyesters obtained by a dehydration polycondensation reaction described in JP-A-7-228675, JP-A-6-293826, and the like can be used.

The aliphatic diol used for producing the above aliphatic polyester is, for example, ethylene glycol,
1,3-propanediol, 1,3-butanediol,
1,4-butanediol, 1,5-pentanediol,
3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-
Examples include decanediol, 1,12-dodecanediol, propylene glycol, neopentyl glycol, and the like. These may be used alone or as a mixture of two or more.

The aliphatic dicarboxylic acids used in the production of the aliphatic polyester include, for example, succinic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid,
Examples include suberic acid, azelaic acid, sebacic acid, undecandioic acid, dotecanedioic acid, fumaric acid, dimer acid and the like. These anhydrides can also be used as dicarboxylic acids. These may be used alone or as a mixture of two or more.

The aliphatic polyester comprising the aliphatic diol and the aliphatic dicarboxylic acid used in the present invention preferably has a weight average molecular weight of 3,000 or more. When the weight average molecular weight is less than 3,000, the aliphatic polyester is not dissolved in the organic solvent in the method for producing polylactic acid that undergoes a dehydration polycondensation reaction in an organic solvent in the presence of a catalyst, so that the reaction hardly proceeds. The amount of the aliphatic polyester to be added is preferably 5 to 50% by weight based on polylactic acid. If the amount used is less than 5% by weight, the mechanical properties of the resulting aliphatic block copolyester are almost the same as those of polylactic acid, and if it exceeds 50% by weight, the mechanical properties of the obtained aliphatic block copolyester are Since it is almost the same as that of the polyester, it is impossible to obtain mechanical properties that cannot be obtained with the aliphatic homopolyester. There is no problem if the aliphatic polyester to be added is a polymerization reaction mass containing a catalyst and / or a solvent in addition to powder and pellets.

In the present invention, the aliphatic polyester is subjected to a dehydration polycondensation reaction of lactic acid or an oligomer thereof in an organic solvent in the presence of a catalyst, and at any time at which 98% or more of the total distillate water is distilled off. Is added into the system. When the aliphatic polyester is added at a time when the amount of distilled water is less than 98% of the total distilled water, the aliphatic polyester added is hydrolyzed by the water remaining in the system, and the aliphatic The diol is distilled out of the system together with the water from which the diol is distilled off, and the composition ratio of the monomer units is changed. Here, the total distillate water amount is the total amount of water contained in the lactic acid or oligomer used and water generated when all the terminals of the lactic acid or oligomer are esterified.

In the present invention, lactic acid or its oligomer is subjected to a dehydration polycondensation reaction in an organic solvent in the presence of a catalyst,
By changing the timing of adding the aliphatic polyester, the mechanical properties of the resulting aliphatic block copolyester can be changed. For example, even if the same amount of the same aliphatic polyester is added, when the weight average molecular weight of polylactic acid is added at a sufficiently low point, the tensile yield strength is extremely low, and the tensile yield elongation is lower than that of the added aliphatic polyester. When the same aliphatic block copolyester is obtained and the polylactic acid is added at a high weight-average molecular weight, the tensile yield strength is equivalent to that of polylactic acid, and the tensile yield elongation is equivalent to that of the added aliphatic polyester. A group block copolyester is obtained.
The aliphatic polyester may be added all at once or in portions, and the mechanical properties of the aliphatic block copolyester obtained can be changed by the addition method.

The reaction time in the present invention can be arbitrarily set. Since the reaction is a dehydration polycondensation reaction, the molecular weight of the polymer increases with time. Therefore, by stopping the reaction when the aliphatic block copolyester reaches a desired molecular weight, the weight average molecular weight is from 20,000 to
It is possible to obtain 400,000 aliphatic block copolyesters.

The dehydration polycondensation reaction, solvent dehydration and charging operations of the present invention can be carried out in a continuous, batch or semi-batch mode.

In the present invention, the weight average molecular weight is from 20,000 to 10,000 depending on the type and amount of the raw materials used, the type and amount of the solvent and catalyst used in the reaction, the reaction temperature and the reaction time, the timing of adding the aliphatic polyester, and the like. 400,000, and the tensile yield strength when formed into a film is 100 to 400 kg.
/ Cm ² , and an aliphatic block copolyester having any mechanical properties in a tensile elongation at break in the range of 100 to 1000%. In addition, when the aliphatic block copolyester is crystallized, it shows two melting points of the aliphatic polyester and polylactic acid used. In addition, depending on the timing of addition of the aliphatic polyester, there may be a case where some more melting points are shown in addition to the above two melting points.

The aliphatic block copolyester obtained according to the present invention can be subjected to processing such as injection, stretching, blowing, vacuum forming and the like, and can be used as a substitute for various conventional general-purpose resins depending on its physical properties.

[0036]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. The weight average molecular weight (Mw) of polylactic acid, aliphatic polyester and aliphatic block copolyester was determined by gel permeation chromatography (Showex GPC Shodex GPC).
system-11) and determined by comparison with a standard sample of a polystyrene resin. The tensile yield strength and the tensile yield elongation were determined by punching a test piece from a press film made at 180 ° C using a tabletop hot press machine, according to JIS K-
It was measured according to 7127. The melting points of polylactic acid, aliphatic polyester and aliphatic block copolyester were measured using TG / DTA320 manufactured by Seiko Denshi Kogyo at 80 ° C. for 3 hours at a heating rate of 10 ° C./min. And The composition ratio of monomer units was determined by hydrolyzing an aliphatic copolyester with a 30% aqueous NaOH solution and quantifying the amount of each monomer by HPLC.

Synthesis Example 1 83 g of 90% L-lactic acid was charged into a 500 ml four-necked flask equipped with a thermometer, a stirring blade and a distilling tube, and heated and stirred at 140 ° C. for 3 hours under a nitrogen atmosphere. Water was distilled out of the system. The water distilled so far was 19.9 g (85.7% of the total distilled amount). Next, remove the distilling pipe, attach Dean stack instead, and add tin powder 0.4
g and o-dichlorobenzene (325 g) were added.
The mixture was heated and refluxed at 250 mmHg for 4 hours. At this time, the refluxing o-dichlorobenzene and generated water were separated in a Dean-Stack, and an aqueous layer was sequentially extracted. The water distilled so far was 22.8 g (98.2% of the total distilled amount). The Dean stack was removed, and a tube filled with 50 g of Molecular Sieves 3A was attached instead, so that the solvent distilled by reflux returned to the system through Molecular Sieves 3A. 140 ° C /
The reaction was set at 250 mmHg and reacted for 20 hours. The weight average molecular weight at the end of the reaction was 260,000. 400 ml of chloroform was added to the reaction mass, which was dissolved and suction filtered to remove tin powder. 1400 ml of methanol was added to the obtained chloroform solution, and the precipitated solid was separated by filtration and dried.
56.9 g of a white solid polylactic acid was obtained. Table 1 shows the evaluation results of the obtained polylactic acid, and FIG. 3 shows a chart of 13C-NMR.

Synthesis Example 2 45.7 g of 1,4-butanediol, 57.1 g of succinic acid and 0.6 g of stannous oxide were placed in a 500 ml four-necked flask equipped with a thermometer, a stirring blade and a distilling tube. Water was distilled out of the system while heating and stirring at 150 ° C. for 3 hours under a nitrogen atmosphere. Next, 250 g of o-dichlorobenzene was added,
Remove the distilling tube and replace with molecular sieves 3A5
A tube filled with 0 g was attached, and the solvent distilled off under reflux was returned to the system through Molecular Sieves 3A. The conditions for the dehydration polycondensation reaction were set at 140 ° C./250 mmHg, and the reaction was carried out for 15 hours. The weight average molecular weight at the end of the reaction was 200,000. Chloroform 800 in the reaction mass
After adding and dissolving, tin powder was removed by suction filtration.
2100 ml of methanol was added to the obtained chloroform solution, and the precipitated solid was separated by filtration and dried to obtain 83.2 g of polybutylene succinate as a white solid. Table 1 shows the evaluation results of the obtained polybutylene succinate, and 13C-NM.
The chart of R is shown in FIG.

Example 1 83 g of 90% L-lactic acid was charged into a 500 ml four-necked flask equipped with a thermometer, a stirring blade and a distilling tube, and heated and stirred at 140 ° C. for 3 hours under a nitrogen atmosphere. Water was distilled out of the system. The water distilled so far was 19.9 g (85.7% of the total distilled amount). Next, remove the distilling pipe, attach Dean stack instead, and add tin powder 0.4
g and o-dichlorobenzene (325 g) were added.
The mixture was heated and refluxed at 250 mmHg for 4 hours. At this time, the refluxing o-dichlorobenzene and generated water were separated in a Dean-Stack, and an aqueous layer was sequentially extracted. The water distilled so far was 22.8 g (98.2% of the total distilled amount). At this time, 15.1 g of the polybutylene succinate obtained in Synthesis Example 2 was added, and the mixture was heated and refluxed at 140 ° C./250 mmHg for 20 hours. The post-treatment was performed according to Synthesis Example 1 to obtain 72.0 g of a white solid block copolymer. The weight average molecular weight of the block copolymer at the end of the reaction was 280,000. Table 1 shows the evaluation results of the obtained block copolymers.
Shown in The obtained block copolymer had a lower tensile yield strength than the polylactic acid of Synthesis Example 1 and a tensile yield elongation equivalent to that of the polybutylene succinate of Synthesis Example 2. FIG. 1 shows a TG / DTA chart of the obtained polymer.

Example 2 83 g of 90% L-lactic acid was charged into a 500 ml four-necked flask equipped with a thermometer, a stirring blade, and a distillation tube, and heated and stirred at 140 ° C. for 3 hours under a nitrogen atmosphere. Water was distilled out of the system. The water distilled so far was 19.9 g (85.7% of the total distilled amount). Next, remove the distilling pipe, attach Dean stack instead, and add tin powder 0.4
g and o-dichlorobenzene (325 g) were added.
The mixture was heated and refluxed at 250 mmHg for 5 hours. At this time, the refluxing o-dichlorobenzene and generated water were separated in a Dean-Stack, and an aqueous layer was sequentially extracted. The water distilled so far was 22.9 g (98.5% of the total distilled amount). At this time, 15.1 g of the polybutylene succinate obtained in Synthesis Example 2 was added, and the mixture was heated and refluxed at 140 ° C./250 mmHg for 20 hours. The post-treatment was performed according to Synthesis Example 1 to obtain 72.0 g of a white solid block copolymer. The weight average molecular weight of the block copolymer at the end of the reaction was 250,000. Table 1 shows the evaluation results of the obtained block copolymers.
Shown in The obtained block copolymer had a lower tensile yield strength than the block copolymer of Example 1 and a tensile yield elongation equivalent to that of the polybutylene succinate of Synthesis Example 2. FIG. 5 shows a 13C-NMR chart of the obtained polymer.

Example 3 83 g of 90% L-lactic acid was charged into a 500 ml four-necked flask equipped with a thermometer, a stirring blade and a distillation tube, and heated and stirred at 140 ° C. for 3 hours under a nitrogen atmosphere. Water was distilled out of the system. The water distilled so far was 19.9 g (85.7% of the total distilled amount). Next, remove the distilling pipe, attach Dean stack instead, and add tin powder 0.4
g and o-dichlorobenzene (325 g) were added.
The mixture was heated and refluxed at 250 mmHg for 3 hours. At this time, the refluxing o-dichlorobenzene and generated water were separated in a Dean-Stack, and an aqueous layer was sequentially extracted. The water distilled so far was 22.8 g (98.2% of the total distilled amount). At this time, 15.1 g of the polybutylene succinate obtained in Synthesis Example 2 was added, and the mixture was heated and refluxed at 140 ° C./250 mmHg for 20 hours. The post-treatment was performed according to Synthesis Example 1 to obtain 72.0 g of a white solid block copolymer. The weight average molecular weight of the block copolymer at the end of the reaction was 300,000. Table 1 shows the evaluation results of the obtained block copolymers.
Shown in The resulting block copolymer had a lower tensile yield strength than the block copolymer of Example 2 and a tensile yield elongation equivalent to that of the polybutylene succinate of Synthesis Example 2.

Comparative Example 1 Water was distilled out of the system while heating and stirring at 140 ° C. for 3 hours, and then tin powder and o-dichlorobenzene were added, and simultaneously the polybutylene succinate 15.1 obtained in Synthesis Example 2 was added.
72.0 g of a white solid copolymer was obtained according to Synthesis Example 1 except that g was added. The weight average molecular weight of the polylactic acid at the time of addition of polybutylene succinate was 0.1000 or less, and the weight average molecular weight of the block copolymer at the end of the reaction was 0.4000. The resulting copolymer was very brittle and could not be formed into a film.

Synthesis Example 3 45.7 g of 1,4-butanediol, 57.1 g of succinic acid and 0.6 g of stannous oxide were placed in a 500 ml four-necked flask equipped with a thermometer, a stirring blade and a distilling tube. And water was distilled out of the system while heating and stirring at 150 ° C. for 3 hours under a nitrogen atmosphere. Next, 250 g of o-dichlorobenzene was added, the distilling tube was removed, and molecular sieves 3 was used instead.
A tube filled with 50 g of A was attached, and the solvent distilled off under reflux was returned to the system through Molecular Sieves 3A. Dehydration polycondensation reaction conditions are 140 ° C / 250mmH
g, and allowed to react for 2 hours, polybutylene succinate / o having a weight average molecular weight of 20,000 and a polymer concentration of 25% by weight.
-A dichlorobenzene solution was obtained.

Example 4 The conditions for the dehydration polycondensation reaction were set at 110 ° C./90 mmHg, and the reaction was carried out for 10 hours.
9 g (98.8% of the total distillation amount). The polybutylene succinate / o- obtained in Synthesis Example 3 was added to the reaction mass.
According to Synthesis Example 1 except that 60.4 g of a dichlorobenzene solution was added and the reaction was carried out for 5 hours, 71.9 g of a block copolymer as a white solid was obtained. The weight average molecular weight of the block copolymer at the end of the reaction was 130,000. Table 1 shows the evaluation results of the obtained block copolymers. The resulting block copolymer had a lower tensile yield strength than the block copolymer of Example 3 and a tensile yield elongation equivalent to that of the polybutylene succinate of Synthesis Example 2.

Example 5 The conditions for the dehydration polycondensation reaction were set at 110 ° C./90 mmHg, and the reaction was carried out for 10 hours.
9 g (98.8% of the total distillation amount). The polybutylene succinate / o- obtained in Synthesis Example 3 was added to the reaction mass.
72.0 g of a white solid block copolymer was obtained according to Synthesis Example 1 except that 60.4 g of a dichlorobenzene solution was added, followed by reaction for 15 hours. The weight average molecular weight of the block copolymer at the end of the reaction was 130,000. Table 1 shows the evaluation results of the obtained block copolymers. The resulting block copolymer had a lower tensile yield strength than the block copolymer of Example 4, and a tensile yield elongation equivalent to that of the polybutylene succinate of Synthesis Example 2. FIG. 2 shows a TG / DTA chart of the obtained polymer.

Comparative Example 2 After water was distilled out of the system while heating and stirring at 140 ° C. for 3 hours, tin powder and o-dichlorobenzene were added, and simultaneously the polybutylene succinate / o- obtained in Synthesis Example 3 was added. According to Example 5, except that 60.4 g of a dichlorobenzene solution was added, 71.8 g of a block copolymer as a white solid was obtained. The weight average molecular weight of the polylactic acid at the time of addition of polybutylene succinate was 0.1000 or less, and the weight average molecular weight of the block copolymer at the end of the reaction was 30 thousand. The resulting copolymer was very brittle and could not be formed into a film.

Example 6 The conditions for the dehydration polycondensation reaction were set at 110 ° C./90 mmHg, and the reaction was carried out for 5 hours. The water distilled so far was 22.7.
5 g (98% of the total distillate). 72.0 g of a white solid block copolymer was obtained in the same manner as in Example 1 except that 15.1 g of polybutylene succinate (Bionole # 1020, weight average molecular weight: 120,000) manufactured by Showa Polymer Co., Ltd. was added to the reaction mass. The weight average molecular weight of the block copolymer at the end of the reaction was 180,000. Table 1 shows the evaluation results of the obtained block copolymers. The obtained block copolymer had the same tensile yield strength and tensile yield elongation as the block copolymer of Example 2.

Comparative Example 3 In a 500 ml four-necked flask equipped with a thermometer, a stirring blade, and a distilling tube, 50.0 g of 90% L-lactic acid, 54.1 g of 1,4-butanediol, and 59.1 g of succinic acid. Then, 0.6 g of stannous oxide was charged, and water was distilled out of the system while heating and stirring at 140 ° C. for 3 hours in a nitrogen atmosphere. Next, the distillation tube was removed, and the reaction was carried out at 250 ° C./10 mmHg for 30 hours. The weight average molecular weight at the end of the reaction was 29,000.
800 ml of chloroform was added to the reaction mass, and after dissolving, suction filtration was performed to remove tin powder. 2800 ml of methanol was added to the obtained chloroform solution, and the precipitated solid was separated by filtration and dried to obtain a white solid random copolymer 132.5%.
g was obtained. The obtained random copolymer was very brittle and could not be formed into a film. FIG. 6 shows a 13C-NMR chart of this random copolymer.

[0049]

[Table 1]

[0050]

According to the present invention, by changing the timing of addition to the polylactic acid production process, the same aliphatic polyester can be used to obtain a tensile yield strength, which cannot be obtained with conventional polylactic acid, of 100 to 400 kg / cm. ² , tensile elongation at break is 100 ~
Aliphatic copolyesters having any mechanical properties in the range of 1000% can be made.

[Brief description of the drawings]

FIG. 1 is a TG / DTA chart of a first embodiment.

FIG. 2 is a chart of TG / DTA of a fifth embodiment.

FIG. 3 is a chart of ¹³ C-NMR of Synthesis Example 1.

FIG. 4 is a chart of ¹³ C-NMR of Synthesis Example 2.

FIG. 5 is a chart of ¹³ C-NMR of Example 2.

6 is a chart of ¹³ C-NMR of Comparative Example 3. FIG.

────────────────────────────────────────────────── (5) References JP-A-8-300570 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (9)

(57) [Claims] 1. A lactic acid or its oligomer is subjected to a dehydration polycondensation reaction in an organic solvent in the presence of a catalyst to give a total distilled water amount of 98.
% Of an aliphatic polyester consisting of an aliphatic diol and an aliphatic dicarboxylic acid and having a weight-average molecular weight of 3000 or more at an arbitrary point of time when water is removed by distillation. Polyester manufacturing method. 2. Lactic acid or its oligomer is subjected to dehydration polycondensation reaction in an organic solvent in the presence of a catalyst, and the total amount of distilled water is 98%.
% Of an aliphatic polyester composed of an aliphatic diol and an aliphatic dicarboxylic acid having a weight-average molecular weight of 3000 or more is added at an arbitrary point of time when water of at least% is distilled off, and subjected to a dehydration polycondensation reaction. But 100-400kg /
A method for producing an aliphatic block copolyester having a cm ² and a tensile elongation at break of 100 to 1000%. 3. A dehydration polycondensation reaction of lactic acid or an oligomer thereof in an organic solvent in the presence of a catalyst to give a total distilled water amount of 98.
% Or more of water is distilled off at any time, and an aliphatic polyester composed of an aliphatic diol and an aliphatic dicarboxylic acid having a weight average molecular weight of 3,000 or more is added to carry out a dehydration polycondensation reaction. A method for producing an aliphatic block copolyester having a melting point. 4. The method according to claim 1, wherein the aliphatic diol is ethylene glycol or 1,4-butanediol. 5. The method according to claim 1, wherein the aliphatic dicarboxylic acid is succinic acid or adipic acid. 6. The catalyst used in the reaction is metallic tin and / or
4. The method according to claim 1, wherein the compound is a divalent tin compound. 7. The divalent tin compound comprises an organotin, stannous chloride,
7. The method according to claim 6, wherein the method is selected from stannous hydroxide, stannous sulfate, and stannous oxide. 8. The method according to claim 1, wherein the organic solvent used in the reaction is anisole, diphenyl ether, naphthalene, o-dichlorobenzene or a mixture thereof. 9. An aliphatic block copolyester obtained by the production method according to claim 1, 2 or 3.