JP3360762B2 - Degradable container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to degradable containers. More specifically, the present invention relates to a container made of a thermoplastic polymer composition mainly composed of an aliphatic polyester, having degradability in a natural environment and having excellent flexibility.

[0002]

2. Description of the Related Art Conventionally, polyethylene, polyethylene terephthalate, polyvinyl chloride, and polypropylene resins have been used as plastic containers. But,
Such polyolefin-based or aromatic polyester-based polymer has almost no degradability under natural environment,
When discarded and buried, it remains semi-permanently in the ground.
Discarded plastics also cause problems such as spoiling the landscape and destroying the living environment of marine life. In addition, a container formed of a copolymer of polyhydroxybutyrate and polyhydroxyvalerate, which is effective for decomposability, and polylactic acid has been developed. However, since the container has insufficient flexibility, there are problems such as a hard touch and a weak impact.

On the other hand, aliphatic polyesters are known as thermoplastic and degradable polymers. However, the esterification reaction between polyhydric alcohols and polybasic acids is a sequential reaction, and the molecular weight increases with the reaction time, but the water generated at this time has the effect of reducing the molecular weight of the polycondensate by hydrolysis. Therefore, the aliphatic polyester obtained by direct condensation has a molecular weight of at most 10,000.
It was said to be a degree.

[0004] JP-A-4-189822, JP-A-4-189822
No. 189823 discloses a saturated polyester having a number average molecular weight of 5,000 or more, a terminal group substantially a hydroxyl group, and an acid component of a compound having 3 or more carbon atoms or a mixture thereof. In the state, by adding a diisocyanate having an isocyanate group equivalent to 1/10 to 2 equivalents of the hydroxyl group,
It describes a method for producing a high molecular weight polyester. However, when the isocyanate is present in the polymer chain as described above, a highly toxic diamine is generated in the decomposition process and accumulates in the soil, or when used as a packaging material for food or the like, the partially decomposed diamine is used. There is a risk of contaminating the contents. Aliphatic polyesters are relatively easily hydrolyzed in the presence of water and are also decomposed by microorganisms, so that they can be used for the above applications. However, containers made of these polymers have not been known.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a thermoplastic degradable material which is tough and flexible, and at the same time degrades in the natural environment and does not produce substances which may be toxic due to biodegradability. It is an object to provide a container made of a polymer.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that aliphatic polyesters produced by direct condensation from polyhydric alcohols and polybasic acids and / or hydroxycarboxylic acids. The present invention was completed by finding that a resin having sufficient strength and flexibility, excellent impact resistance, and decomposability in a natural environment could be obtained from a resin mainly composed of

The aliphatic polyester used in the present invention is a polyester of an aliphatic polyhydric alcohol or a mixture thereof and an aliphatic polybasic acid or a mixture thereof, and further, as a monomer, a hydroxycarboxylic acid or a mixture thereof, or an oligomer thereof. Including
It is obtained by performing a direct condensation reaction in a reaction mixture containing an organic solvent.

The degree of polymerization of the aliphatic polyester is from 100 to 20,000. If the degree of polymerization is lower than this, the strength when formed into a molded product is small and is not suitable for practical use. On the other hand, if the degree of polymerization is too high, the viscosity in a molten state when heated is high, and the moldability is poor.

In the polymerization method, a polyhydric alcohol and a polybasic acid, or a compound obtained by adding a hydroxycarboxylic acid, are subjected to a heat condensation reaction in an organic solvent, and the produced water or excess monomer is added to the reaction system together with the organic solvent. And an organic solvent having an amount of water or monomer less than the amount of water or monomer dissolved in the distilled organic solvent is added to the reaction system as an additional solvent while reacting.

The polyhydric alcohols have an aliphatic hydroxyl group and include, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4 -Butanediol, 3-methyl-1,5-pentanediol,
1,6-hexanediol, 1,9-nonanediol,
Neopentyl glycol, polytetramethylene glycol 1,4-cyclohexanedimethanol, 1,4-benzenedimethanol and the like can be mentioned.

The polybasic acids are those having an aliphatic carboxyl group, such as succinic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, and the like.
Examples include suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, 1,4-phenylenediacetic acid, phenylsuccinic acid, and the like. Of course, anhydrides of these can also be used.

Examples of the hydroxycarboxylic acids include lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid and the like. Can be

When the molecule has an asymmetric carbon, the D-form and the L-form
, Respectively, or may be a mixture of D-form and L-form, that is, a racemic form. In order to obtain a soft nonwoven fabric, a polymer using ethylene glycol as a polyhydric alcohol and succinic acid as a polybasic acid is preferable in consideration of economy. When lactic acid and glycolic acid are contained, the ratio is preferably 50% or less. , 20% or less is more preferable.

In this heat condensation reaction, a catalyst may or may not be used, but when a catalyst is used, the reaction speed can be increased. Examples of the catalyst to be used include metals of Groups II, III, IV and V of the periodic table, oxides and salts thereof. Specifically, metals such as zinc powder, tin powder, aluminum, magnesium, titanium, and germanium, tin oxide, antimony oxide, zinc chloride, aluminum oxide, magnesium oxide, metal oxides such as titanium oxide, stannous chloride, Metal halides such as stannic chloride, stannous bromide, stannic bromide, antimony fluoride, zinc chloride, magnesium chloride, aluminum chloride, tin sulfate,
Sulfates such as zinc sulfate and aluminum sulfate, carbonates such as magnesium carbonate and zinc carbonate, organic carboxylate salts such as tin acetate, tin octoate, tin lactate, zinc acetate and aluminum acetate, tin trifluoromethanesulfonate, trifluoromethane Organic sulfonates such as zinc sulfonate, magnesium trifluoromethanesulfonate, tin methanesulfonate, and tin p-toluenesulfonate are exemplified. In addition, organometallic oxides of the above metals such as dibutyltin oxide,
Alternatively, metal alkoxides of the above metals such as titanium isopropoxide, alkyl metals of the above metals such as diethyl zinc, and ion exchange resins such as Dowex and Amberlite can be used.

The amount used is 0.0001 to 10% of the aliphatic polyhydric alcohol, aliphatic polybasic acid, aliphatic hydroxycarboxylic acid or oligomer thereof used.
It is preferable to be 0.001 to 2% by weight in consideration of economy and use in a living body.

The solvent used in the production of the polyester according to the present invention includes, for example, hydrocarbon solvents such as toluene, xylene and mesitylene, chlorobenzene,
Bromobenzene, iodobenzene, dichlorobenzene,
Halogen solvents such as 1,1,2,2-tetrachloroethane and p-chlorotoluene, ketone solvents such as 3-hexanone, acetophenone and benzophenone, dibutyl ether, anisole, phenetole, o-dimethoxybenzene, p-dimethoxybenzene , 3-methoxytoluene, dibenzyl ether, benzyl phenyl ether,
Ether solvents such as methoxynaphthalene; thioether solvents such as phenylsulfide and thioanisole; ester solvents such as methyl benzoate, methyl phthalate and ethyl phthalate; diphenyl ether; or 4-methylphenyl ether and 3-methylphenyl ether , 3-phenoxytoluene or other alkyl-substituted diphenyl ethers, or 4-bromophenyl ether, 4-chlorophenyl ether, 4-bromophenyl ether, 4-
Halogen-substituted diphenyl ethers such as methyl-4'-bromodiphenyl ether, or alkoxy-substituted diphenyl ethers such as 4-methoxydiphenyl ether, 4-methoxyphenyl ether, 3-methoxyphenyl ether, and 4-methyl-4'-methoxydiphenyl ether; or dibenzofuran And diphenyl ether solvents such as cyclic diphenyl ethers such as xanthene. These may be used as a mixture. As the solvent, those which can be easily separated from water are preferable, and in particular, an ether solvent, an alkyl-aryl ether solvent and a diphenyl ether solvent are more preferable in order to obtain a polyester having a high average molecular weight. Solvents and diphenyl ether solvents are particularly preferred. The use amount of these solvents is preferably 10 to 80% in terms of the concentration of the obtained polymer.

In the production of the aliphatic polyester, it is preferable to distill off the produced water or excess monomer out of the reaction system by azeotropic distillation of the organic solvent used with water or the monomer. If the amount of water or monomer contained in the organic solvent distilled off by azeotropic distillation is higher than the solubility of water or monomer in the organic solvent, the water or monomer may be removed by liquid separation and then returned to the reaction system. In order to remove the water or the monomer dissolved in the organic solvent used, the water or the monomer may be treated with a dehydration or de-monomer, or the content of the water or the monomer may be reduced by distillation or the like, and then returned to the reaction system. Instead of the organic solvent distilled off by azeotropic distillation, fresh water or an organic solvent having a low monomer content may be charged. At the beginning of the reaction, water or excess monomer is removed under reduced pressure, then an organic solvent is added, and a part of the organic solvent is removed from the reaction mixture containing the organic solvent, whereby the water or the monomer in the reaction mixture is removed. It may be a predetermined value.

That is, the condensation reaction proceeds at least at a certain stage of the reaction while using a solvent to remove water or the monomer. In this embodiment, the solvent may or may not azeotrope with the water or the monomer. It may or may not separate with water or monomer.
Further, other embodiments include a method in which an excess solvent is charged in advance and a method of dehydrating and demonomerizing by simply extracting the solvent, and a method of dehydrating and demonomerizing the reaction solvent using another solvent. It is. As a further modification, water or monomer may be removed while the reaction solvent itself is in a liquid state.
The reaction temperature may be set to a predetermined temperature even if the boiling point is lowered because the solvent azeotropes with water or the monomer.

The average molecular weight of the aliphatic polyester also depends on the amount of water or monomer in the organic solvent to be charged into the reaction system and depends on the type of the solvent.
m and a high water or monomer content, the resulting aliphatic polyester has a weight average molecular weight of 15,000 to
50,000. Even with the high water content and high monomer content, the use of a diphenyl ether-based solvent results in 40,000 to 5
It is surprising that aliphatic polyesters with a weight average molecular weight of 000 are obtained. Further, in order to obtain a high average molecular weight aliphatic polyester, it is desirable that the amount of water or monomer in the organic solvent to be charged into the reaction system is low. By removing or reducing water or monomer to return to the reaction system, or by charging a new organic solvent having low water or monomer amount into the reactor, the amount of water or monomer to be charged is reduced to 50 ppm or less. An aliphatic polyester having a weight average molecular weight of 50,000 to 300,000 can be obtained.

As the dehydrating and demonomerating agent used for obtaining the polyester having a high average molecular weight used in the container of the present invention, molecular sieve 3A, molecular sieve 4A,
Molecular sieves such as Molecular Sieve 5A and Molecular Sieve 13X, alumina, silica gel, calcium chloride, calcium sulfate, diphosphorus pentoxide, concentrated sulfuric acid, magnesium perchlorate, barium oxide, calcium oxide, potassium hydroxide, sodium hydroxide, or hydrogen Metal hydrides such as calcium hydride, sodium hydride, and lithium aluminum hydride; and alkali metals such as sodium are included. Among them, molecular sieves are preferable from the viewpoint of easy handling and regeneration.

An example of the method for producing a polyester according to the present invention is as follows. That is, a reactor equipped with a separator (for example, a Dean Stark trap) is charged with a solvent and a predetermined amount of ethylene glycol, succinic acid, lactic acid and a predetermined amount of a catalyst, and the reactor is heated,
The solvent and water or excess monomer are distilled off by azeotropic distillation and led to a separator. Water or monomer having a solubility higher than that of the solvent is separated by a separator and removed from the system, and the solvent containing water or monomer corresponding to the solubility is returned to the reaction system. The weight average molecular weight at this stage is from 500 to 1,000, and the weight average molecular weight may be about 5,000. The reaction time during this period is approximately 0.5 hours to several hours. This oligomerization reaction may be carried out in advance in a separate reactor without solvent, without a catalyst, under reduced pressure, or with a solvent without a catalyst. As the reaction proceeds at the solvent distillation temperature as it is, water or monomer generated is removed, and the reaction may be continued while returning the solvent saturated with water or monomer to the reaction system. Depending on the type,
Those having a weight average molecular weight of 15,000 to 50,000 are obtained.

In order to obtain a polymer having a higher molecular weight, water or excess monomer in the raw material is almost distilled off, then the separator is removed, and a tube filled with a desiccant such as molecular sieve is attached to the solvent to be distilled. Either reflux through the tube, distill off the solvent in another reactor with desiccant and return it to the reactor, or add fresh water or low monomer content solvent. Charge the reactor. According to these methods, the amount of water or monomer in which the solvent is dissolved is reduced to 50 ppm or less, and the reaction is continued for several tens of hours.
From 000 to 300,000 copolymers can be obtained. After the reaction is completed, any method may be used to obtain the desired copolymer.For example, chloroform may be added to the reaction solution, heated, then discharged into acetone, and the precipitated crystals are filtered and dried to obtain the desired copolymer. Can be

The weight average molecular weight of the aliphatic polyester obtained by this method can be determined by changing the type of solvent, the type and amount of the catalyst, the reaction rate, the reaction time, the method of treating the solvent distilled off by azeotropic distillation, and the like. A variety can be obtained, but is about 15,000-300,000.

In the method of the present invention, when the condensation reaction is carried out in the presence of a catalyst, the remaining catalyst in the polymer affects the thermal stability and weather resistance of the polymer. preferable. As a preferable removal method, a method in which a polymer in the form of a powder obtained by stirring the condensation reaction solution or cooling as it is, is brought into contact with an acidic substance in the presence of a hydrophilic organic solvent.

The hydrophilic organic solvent used in this method includes alcohols such as methanol, ethanol, isopropanol and butanol, ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran and dioxane, and carboxylic acids such as acetic acid and butyric acid. Examples thereof include acids, nitriles such as acetonitrile, and amides such as N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethylimidazolidinone, and hexamethylphosphoramide. In particular, alcohols which are inexpensive and do not dissolve the polymer are preferred.

Examples of the acidic substance include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and organic acids such as acetic acid and p-toluenesulfonic acid. Inexpensive hydrochloric acid, sulfuric acid, and nitric acid are particularly preferable. The amount of the acidic substance used is 0.0001 to 5.0 mol / 100 parts by weight, preferably 0.001 to 1 mol / 100 parts by weight, based on the polymer.
If the amount is less than 0.0001 mol, the effect of removing the catalyst may be deteriorated. If the amount is more than 5.0 mol, problems such as deterioration of the polymer may occur.

The solid state of the polymer used in this method may be in the form of powder, granule, granule, flake, or block.
There is a conventional method of once dissolving a polymer in a good solvent and then dropping a poor solvent or dropwise into a poor solvent, or a method of dissolving in a specific solvent by heating and then cooling and crystallizing.

As the properties of the polymer, the bulk density is preferably 0.60 g / ml or less, and more preferably 0.05 to 0.5 g / ml. Bulk density is 0.60g
If the bulk density is less than 0.05 g / ml, there is no problem in removing the catalyst if the bulk density is less than 0.05 g / ml. However, there is a case where operational problems arise due to poor filterability after treatment. The polymer and the acidic substance are preferably brought into contact with each other preferably at a solid content of about 3 to 40% by weight in a hydrophilic organic solvent and at a contact temperature of 0 to 100%.
° C, particularly preferably 0 to 60 ° C, contact time 0.1 to 24
It is about an hour, particularly preferably about 0.5 to 8 hours.

The aliphatic polyester of the present invention is made into a thermoplastic polymer composition by using a generally known thermoplastic polymer or plasticizer and various modifiers. The proportion occupied by the aliphatic polyester in the thermoplastic polymer composition is an arbitrary proportion depending on the intended degradability,
Generally, 50% or more is preferable. In addition, all known kneading techniques can be applied to the production of the thermoplastic polymer composition, and the composition is used in the form of pellets, rods, powders, and the like.

Next, in order to obtain a container using the thermoplastic polymer composition according to the present invention, the composition is heated and melted by an extruder, extruded from a die into a tube (parison), and the parison is not solidified by cooling. In general, a molding method is used in which the lower part of the parison is pinched off and fused, and air is blown into the inside to form a container (extrusion blow molding method). There are a stretch blow molding method and an injection stretch blow molding method, and any method may be used. The molding conditions are appropriately determined depending on the molding machine, the type of the polymer, and the like, and some of them are exemplified. For example, in the case of injection stretch blow molding, injection molding temperature; 120 to 250 ° C., stretching temperature adjusting pot temperature; 90 to 230 ° C., stretch blow fresh stretch ratio; 1.2 to 3.5 times horizontal stretch ratio; Blow air pressure: 4 to 20 kg / cm2 In the case of extrusion stretch blow molding, extrusion molding temperature: 120 to 250 ° C Preform mold temperature; 50 to 130 ° C It is preferable to carry out molding under various conditions of 0.2 to 3.5 times horizontal stretching ratio; 1.2 to 6.0 times blow air pressure; 4 to 20 kg / cm 2.

[0031]

EXAMPLES Examples will be shown below, but the present invention is not limited to these examples. The weight average molecular weight in the examples was determined by gel permeation chromatography (column temperature: 40 ° C., chloroform solvent) in comparison with a polystyrene standard sample.

Production Example 1 200.0 g of diphenyl ether and 0.931 g of metal tin were added to 20.0 g of ethylene glycol and 38.1 g of succinic acid.
Was added thereto, and the mixture was heated and stirred at 130 ° C./140 mmHg for 7 hours while flowing water out of the system to form an oligomer. Attach Dean Stark trap to this, 14
Perform azeotropic dehydration at 0 ° C./30 mmHg for 8 hours, and then
A tube filled with 20 g of molecular sieve 3A was attached, allowing the effluent solvent to pass through the molecular sieve layer and return to the reactor and stirred at 130 ° C./17 mmHg for 49 hours. The reaction mass was dissolved in 400 ml of chloroform, added to 3 l of acetone, and reprecipitated.
The mixture was sludged with a solution (HCl 0.7 wt%) for 0.5 hour (three times), washed with IPA, and then dried under reduced pressure at 60 ° C. for 6 hours. The tin content of the catalyst in the polymer is 10 pp
m or less. The weight average molecular weight of this polymer was 124,000.

Production Example 2 50.5 g of 1,4-butanediol and 66.5 succinic acid
g to 293.0 g of diphenyl ether and 2.02 to tin metal
g was added thereto, and the mixture was heated and stirred at 130 ° C./140 mmHg for 7 hours while flowing water out of the system to oligomerize. Attach Dean Stark trap to this, 140
After azeotropic dehydration for 8 hours at 30 ° C./30 mmHg, a tube filled with 40 g of molecular sieve 3A was attached, and the solvent flowing out was returned to the reactor through the molecular sieve layer and stirred at 130 ° C./17 mmHg for 49 hours. .
The reaction mass was dissolved in 600 ml of chloroform,
After re-precipitation in 1 l of acetone, the mixture was sludged with an IPA solution of HCl (0.7 wt% of HCl) for 0.5 hour (three times), washed with IPA, and then dried under reduced pressure at 60 ° C. for 6 hours. The catalyst contained in this polymer had a tin content of 10 ppm or less. The weight average molecular weight of this polymer was 118,000.

Production Example 3 trans-1,4-cyclohexanedimethanol 8
0.8 g and 66.5 g of succinic acid in diphenyl ether 2
93.0 g and 2.02 g of metallic tin were added, and 130 ° C./14
Oligomerization was carried out by heating and stirring at 0 mmHg for 7 hours while flowing water out of the system. To this, Dean Stark
A trap was attached, azeotropic dehydration was performed at 140 ° C./30 mmHg for 8 hours, and then molecular sieve 3A40
g, and allow the solvent to flow out through the molecular sieve layer and return to the reactor.
Stirred at mmHg for 40 hours. The reaction mass is 600m
After dissolving in 1 l of chloroform, adding to 4 l of acetone and reprecipitating, sludge it with an IPA solution of HCl (0.7 wt% of HCl) for 0.5 hour (three times), wash with IPA and then at 60 ° C. under reduced pressure at 60 ° C. Dried for 6 hours. The tin content of the catalyst in the polymer was less than 10 ppm. The weight average molecular weight of this polymer was 122,000.

Production Example 4 To 20.2 g of ethylene glycol, 38.5 g of succinic acid, and 7.3 g of lactic acid, 123.0 g of diphenyl ether and 0.66 g of metal tin were added, and water was discharged outside the system at 125 ° C./140 mmHg for 9 hours. While stirring, the mixture was oligomerized by heating. To this, a Dean Stark trap was attached, azeotropic dehydration was performed at 140 ° C./15 mmHg for 3 hours, and then a tube filled with 30 g of molecular sieve 3A was attached, so that the solvent flowing out returned to the reactor through the molecular sieve layer, 33 at 130 ° C / 13 mmHg
Time-stirred. The reaction mass was dissolved in 720 ml of acetonitrile, 300 ml of a 1N aqueous HCl solution was added, and the mixture was stirred for 0.5 hour. After adding 320 ml of IPA, the mixture was discharged into 4.5 l of methanol and reprecipitated. After washing with 3 l of normal hexane, the solution was dried under reduced pressure. The tin content of the catalyst in the polymer was less than 10 ppm. The weight average molecular weight of this polymer was 147,000.

Production Example 5 35.0 g of 1,4 butanediol and 30.4 of succinic acid
g, adipic acid 9.4 g and diphenyl ether 176
g, 0.66 g of metallic tin, 130 ° C / 140 mmH
The resulting mixture was heated and stirred for 10 hours while flowing water out of the system for 10 hours to form an oligomer. In addition, Dean Stark tra
After azeotropic dehydration at 140 ° C./15 mmHg for 5 hours, a tube filled with 30 g of molecular sieve 3A was attached, and the distilled solvent was returned to the reactor through the molecular sieve layer. ° C / 13mm
Stirred with Hg for 30 hours. The reaction mass was dissolved in 720 ml of acetonitrile, and 300 ml of 1N HCl aqueous solution was added.
After stirring for 0.5 hour, IPA (320 ml) was added, and the mixture was discharged into 4.5 l of methanol and reprecipitated. After washing with 3 l of normal hexane, the solution was dried under reduced pressure. The weight average molecular weight of this polymer was 137,000. The tin content of the catalyst in the polymer was less than 10 ppm. Examples 1 to 5 From the aliphatic polyester obtained in Production Examples 1 to 5, a stretch blow-molded container having a volume of 500 ml and a weight of 30 g was obtained by an injection stretch blow-molding machine. Comparative Examples 1 and 2 Comparative Example 1 was a case where the polymer was changed to poly-L-lactic acid instead of the aliphatic polyester used in Examples 1 to 5, and Comparative Example 2 was a case where the polymer was changed to polyethylene (Mirason-11). A stretch blow-molded container was obtained in the same manner as in Example 1 except for the above.

Each of the stretch blow-molded containers obtained in Examples and Comparative Examples was subjected to the following measurement. Physical property test: A side surface of the container was cut out, and a tensile test in a longitudinal direction of the container was performed using a test piece having a width of 10 mm and a length of 50 mm. The tensile strength test uses a normal tensile tester,
Chuck width 20mm, crosshead speed 50mm /
Measured in minutes. Practical test; The container was filled with water, and at an ambient temperature of 20 ° C,
The container was repeatedly dropped 5 times from a height of 3 meters on a concrete floor, and checked for damage to the container. This was repeated 10 times, and the state of damage during the 10 times was determined. Decomposition test in compost; temperature of the container at 40 ° C, moisture 50%
The container was buried in a compost to perform a decomposition test of the container. The evaluation of the degradability was determined by the change in appearance.

The above results are shown in Table 1 (Table 1), Table 2 (Table 2) and Table 3 (Table 3). Comparative Example 1 has a considerable degree of decomposability in compost, but has insufficient impact resistance, and Comparative Example 2 has no problem in practical tests but has no degradability.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

The container mainly composed of the aliphatic polyester according to the present invention has sufficient strength and flexibility, has excellent impact resistance, and can be buried underground as waste or dumped into the sea or river. When it is used, it decomposes into harmless water and carbon dioxide in a relatively short period of time in the natural environment, like natural products such as paper and wood.

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C08L 67/02 B65D 1/00 A (72) Inventor Kazuhiko Suzuki 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Mitsui Toatsu Chemical Co., Ltd. (56) References JP 4-153215 (JP, A) JP 5-199818 (JP, A) JP 5-339483 (JP, A) JP 5-170885 (JP, A) JP 5 -170886 (JP, A) JP-A-5-70566 (JP, A) JP-A-5-310898 (JP, A) JP-A-5-20973 (JP, A) (58) Fields investigated (Int. . ^7, DB name) B65D 1/00 B29C 49/00 C08G 63/12 C08G 63/60 C08J 5/00 C08L 67/02

Claims (6)

(57) [Claims] 1. A reaction mixture comprising an aliphatic polyhydric alcohol or a mixture thereof and an aliphatic polybasic acid or a mixture thereof or an oligomer thereof, or a hydroxycarboxylic acid or a mixture thereof or an oligomer thereof containing an organic solvent. A decomposable container having excellent impact resistance, comprising a thermoplastic polymer composition containing an aliphatic polyester having a molecular weight of 50,000 or more as a main component and obtained by a direct condensation reaction. 2. The decomposable composite material according to claim 1, wherein the aliphatic polybasic acid is succinic acid. 3. The decomposable composite material according to claim 1, wherein the aliphatic polyhydric alcohol is ethylene glycol or 1,4-butanediol. 4. An aliphatic polybasic acid is succinic acid, and an aliphatic polyhydric alcohol is ethylene glycol or 1,2.
The decomposable composite material according to claim 1, which is 4-butanediol. 5. The decomposable composite material according to claim 1, wherein the content of the catalyst in the aliphatic polyester is 50 ppm or less. 6. The decomposable container according to claim 1, which is obtained by injection stretch blow molding or extrusion stretch blow molding.