JPH0977856A - Degradable polymer composition and method for producing the same - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To obtain a polymer composition free from impurities from polyhydric alcohols, polybasic acids and trihydric or higher polyhydric alcohols by direct dehydration condensation, and to obtain foams and blow bottles. The purpose is to obtain a degradable polymer composition having sufficient strength for a molded product or an adhesive. SOLUTION: An aliphatic polyhydric alcohol or a mixture thereof and an aliphatic polybasic acid or a mixture thereof, or an oligomer or polymer thereof is subjected to a dehydration reaction by heating at least one polyhydric alcohol having a valence of 3 or more. Degradable polymer composition and method for producing the same.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aliphatic polyhydric alcohol or a mixture thereof and an aliphatic polybasic acid or a mixture thereof, or an oligomer or polymer thereof, together with at least one polyhydric alcohol having 3 or more valences. The present invention relates to a method for producing a decomposable polymer composition, which comprises performing a dehydration reaction by heating.

The degradable polymer composition according to the present invention is useful as a substitute or adhesive for medical materials and general-purpose resins. The degradable polymer composition according to the present invention has properties that cannot be satisfied only by the aliphatic polyester. It is possible to provide a molded product or a processed product that takes advantage of the advantageous properties of the degradable polymer composition according to the present invention.

[0003]

As is well known, a method of synthesizing a high molecular weight polyester (a high molecular weight here means a weight average molecular weight of about 15,000 or more) from a polyhydric alcohol and a polybasic acid is a terminal hydroxy group. It is based on a deglycolization reaction of a low molecular weight polyester having a base. Therefore, as the molecular weight increases, the concentration of the terminal group remarkably decreases, and the decomposition reaction due to the concentration at the time of transesterification is also added, so that the molecular weight becomes limited. In particular, the tendency is remarkably observed in the aliphatic polyester. For example, when a high molecular weight saturated polyester is produced by a conventional deglycolization reaction under reduced pressure, it is observed that the molecular weight reaches a maximum and then decreases.

In such a case, it is difficult to obtain a polyester having a molecular weight sufficient to form an aliphatic and tough film by relying on the conventional deglycolization reaction. In other words, it can be said that a film having practical physical properties could not be formed with the molecular weight obtained from the aliphatic polyester. Japanese Patent Laid-Open No. 4-189
No. 822, JP-A-4-189823, a saturated polyester having a number average molecular weight of 5,000 or more, a terminal group substantially a hydroxy group, and an acid component of a compound having 3 or more carbon atoms or a mixture thereof is used. It describes a method for producing a high molecular weight polyester, which comprises adding a diisocyanate having an isocyanate group equivalent to 1/10 to 2 equivalents of a hydroxy group in the above molten state.

However, when an isocyanate group or a urethane bond is present in the polymer chain as described above, a highly toxic diamine may be produced during the decomposition process and accumulated in the soil.
On the other hand, the esterification reaction between polyhydric alcohols and polybasic acids is a sequential reaction, and the molecular weight increases with the reaction time. Further, the water produced at this time has an action of lowering the molecular weight of the polycondensate by a hydrolysis action, and therefore it was necessary to remove the produced water out of the system in order to obtain a high molecular weight aliphatic polyester. .

Therefore, the inventors of the present invention have already disclosed in US Pat. No. 5,401,796 (inventors; Kajima Grain, Kameoka Taiji,
Chojiro Higuchi, Masanobu Amioka, Akihiro Yamaguchi, Applicant; Mitsui Toatsu Chemicals, Inc., in which aliphatic polyhydric alcohols or mixtures thereof and aliphatic polybasic acids or mixtures thereof,
Also disclosed is a technique for producing an aliphatic polyester having a weight average molecular weight of 15,000 or more, which comprises subjecting an oligomer thereof to a heat dehydration reaction in a reaction mixture containing an organic solvent.

By adopting the technique disclosed in US Pat. No. 5,401,796, for the first time, an aliphatic polyester is dehydrated and condensed without using a coupling agent such as diisocyanate to obtain a high molecular weight aliphatic polyester. It is possible to get it. However, when this polymer is molded into a foam or blow bottle, the low melt tension makes the work difficult, and a polymer having a high melt tension has been desired. Further, when it is used as an adhesive, one having a high melt tension has been desired in order to exert sufficient adhesive performance.

[0008]

The problem to be solved by the present invention is that the problems of the above-mentioned prior art, that is, the generation of a toxic coupling agent decomposition product due to biodegradation, does not occur, and impurities are reduced. Bunkaisei polymer composition having a low degree of coloring, having a melt tension and a molecular weight suitable for the production of molded products such as blown bottles and blow bottles and adhesives, and having excellent degradability and a composition thereof It is to provide a manufacturing method.

[0009]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the inventors of the present invention have proposed US Pat.
While further developing and applying the technical idea which was the basis for completing the invention disclosed in No. 01,796, as a result of diligent study, it was found that aliphatic polyhydric alcohols such as ethylene glycol and 1,4-butanediol were obtained. An aliphatic polybasic acid such as succinic acid or an oligomer or polymer thereof is subjected to a heat dehydration reaction in an organic solvent with a polyhydric alcohol having a valence of 3 or more in the presence of a catalyst or in the absence of a catalyst to form a raw product. A degradable polymer composition that does not produce substances that may be toxic due to decomposition, has few impurities, is low in coloring degree, and is suitable for molded articles such as foams and blow bottles and adhesives and has outstanding melt tension and degradability The inventors have found that it is possible to obtain the above, and have completed the present invention.

For example, by reacting 1,4-butanediol, succinic acid, and a polyhydric alcohol such as glycerin, trimethylolpropane and pentaerythritol in an organic solvent in the presence of a catalyst, a polymer having a high molecular weight can be obtained. Moreover, the degradable polymer composition containing the obtained copolymer has a high melt tension, and a processed product such as a foam or a molded product by blow molding can be obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The degradable polymer composition of the present invention is
It can be obtained by reacting an aliphatic polyhydric alcohol and an aliphatic polybasic acid with a trihydric or higher polyhydric alcohol in the presence of a catalyst or in the absence of a catalyst in an organic solvent. In the case of carrying out the reaction in an organic solvent, in order to obtain a polymer having a higher molecular weight, the produced water or excess monomer is distilled out of the reaction system together with the organic solvent,
The reaction is carried out while charging water or an organic solvent having the following water content of the monomer or an organic solvent having a monomer content in the reaction system as an additional solvent.

The organic solvent which can be used in the production method of the present invention is, for example, a hydrocarbon solvent such as toluene, xylene, mesitylene, chlorobenzene, bromobenzene, iodobenzene, dichlorobenzene, 1,1,2,2-tetrahydrofuran. Chlorethane, halogen-based solvents such as p-chlorotoluene,
Ketone solvents such as 3-hexanone, acetophenone and benzophenone, dibutyl ether, anisole, phenetole, o-dimethoxybenzene, p-dimethoxybenzene, 3-methoxytoluene, dibenzyl ether, benzylphenyl ether, methoxynaphthalene, etc. Ether solvents, phenyl ether, thioether solvents such as thioanisole, methyl benzoate, methyl phthalate,
Ester solvent such as ethyl phthalate, diphenyl ether, or alkyl-substituted diphenyl ether such as 4-methylphenyl ether, 3-methylphenyl ether, 3-phenoxytoluene, or 4-bromophenyl ether, 4-chlorophenyl ether, 4-bromo Halogen-substituted diphenyl ether such as diphenyl ether, 4-methyl-4'-bromodiphenyl ether, or 4-methoxydiphenyl ether, 4-methoxyphenyl ether, 3-methoxyphenyl ether, 4-
Examples thereof include alkoxy-substituted diphenyl ethers such as methyl-4′-methoxydiphenyl ether and diphenyl ether solvents such as cyclic diphenyl ethers such as dibenzofuran and xanthene, and these may be used as a mixture. And as the solvent, those that can be easily separated from water by liquid separation are preferable, and in particular, in order to obtain an aliphatic polyester having a high average molecular weight, an ether solvent, an alkyl-aryl ether solvent and a diphenyl ether solvent are more preferable, but an alkyl- Aryl ether solvents and diphenyl ether solvents are particularly preferred. The amount of these solvents used is 10 to 8 depending on the concentration of the obtained polymer.
It is preferably 0%.

In the production method of the present invention, in order to distill the produced water or the excess monomer out of the reaction system, it is preferable to carry out azeotropic distillation of the used organic solvent and water or the monomer. The azeotropically distilled organic solvent may be returned to the reaction system after removing the water or the monomer by liquid separation when the amount of the contained water or the monomer is higher than the solubility of the water or the monomer in the organic solvent, Further, in order to remove water or a monomer dissolved in the organic solvent used, it may be returned to the reaction system after dehydration, treatment with a demomerizing agent, or reduction of the content content of water or a monomer by distillation or the like. . Further, in place of the organic solvent distilled by azeotropic distillation, new water or an organic solvent having a low monomer content may be charged. Further, water or excess monomer is removed under reduced pressure at the beginning of the reaction, an organic solvent is added thereafter, and a part of the organic solvent is removed from the reaction mixture containing the organic solvent to remove water or monomer from the reaction mixture. It can also be a predetermined value.

That is, at least at a certain stage of the reaction, the condensation reaction is advanced while removing the water or the monomer by using the solvent. In this embodiment, the solvent may or may not be azeotropic with the water or the monomer. Well, it may or may not be separated from water or the monomer.
Further, as another embodiment, a method of preliminarily charging an excess solvent and dehydrating by simply extracting the solvent, a method of drying the reaction solvent using another solvent, and the like are also included. As a further modification, water may be removed while the reaction solvent itself remains liquid. Further, regarding the reaction temperature of the present invention,
Since the solvent is azeotropic with water, it may be carried out at a predetermined temperature even if the boiling point is lowered.

The average molecular weight of the decomposable polymer composition depends on the amount of water or monomer of the organic solvent charged into the reaction system, and it depends on the kind of the solvent, but the solvent is 400 to 500 pp.
When it has a high water content of m, the degradable polymer composition has a weight average molecular weight of 15,000 to 50,000.
It is. It is surprising that a degradable polymer composition having a weight average molecular weight of 40,000 to 50,000 can be obtained by using a diphenyl ether solvent or orthodichlorobenzene even with the above high water content and high monomer content. In order to obtain a decomposable polymer composition having a higher average molecular weight, it is desirable that the amount of water or monomer of the organic solvent to be inserted into the reaction system is low. The amount of water or monomer to be inserted is reduced to 50 p by adding water to the reaction system after treatment to remove or reduce water and returning it to the reaction system or inserting a new organic solvent having a low water content.
By setting it to be pm or less, the weight average molecular weight Mw50,
000 to 500,000 degradable polymer compositions can be obtained.

In the production method of the present invention, as the dehydrating and demomerizing agent used to obtain a degradable polymer composition having a high average molecular weight, molecular sieve 3A, molecular sieve 4A, molecular sieve 5A, molecular sieve 13X, etc. can be used. Molecular sieves, alumina,
Silica gel, calcium chloride, calcium sulfate, phosphorus pentoxide, concentrated sulfuric acid, magnesium perchlorate, barium oxide,
Calcium oxide, potassium hydroxide, sodium hydroxide,
Alternatively, examples include metal hydrides such as calcium hydride, sodium hydride, and lithium aluminum hydride, and alkali metals such as sodium. Among them, molecular sieves are preferable because they are easy to handle and regenerate.

The reaction temperature in the production method of the present invention is preferably 80 to 200 ° C., more preferably 110 to 170 ° C., in consideration of the polymer production rate and the thermal decomposition rate of the produced polymer. The condensation reaction is usually carried out at the distillation temperature of the organic solvent used under normal pressure.
When a high-boiling organic solvent is used to keep the reaction temperature in a preferable range, it may be carried out under reduced pressure, and when a low-boiling organic solvent is used, it may be carried out under pressure.

The polyhydric alcohols used in the present invention are, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,3-
Examples thereof include butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol and polytetramethylene glycol.
Further, regarding polybasic acids, succinic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecane, D-form when it has an asymmetric carbon in the molecule, Each of the L-forms may be alone, or a mixture of the D-form and the L-form, that is, a racemic form. Examples include diacids and dodecanedioic acid. Also, these anhydrides may be used.

The polyhydric alcohol having a valence of 3 or more may be any commercially available one, but glycerin, trimethylolpropane and pentaerythritol are particularly easily available. The amount of polyhydric alcohol with a valence of 3 or higher is
The aliphatic polyhydric alcohol and the aliphatic polybasic acid to be used, or the oligomer thereof are preferably 0.1 to 10% by weight, and considering economic efficiency, 0.5 to 5% by weight is preferable. The method for adding the trihydric or higher polyhydric alcohol is not particularly limited.
It may be added from the beginning of the reaction or after the oligomerization. Alternatively, it may be added to the reaction mass of the polymer after polymerization.

In the reaction of the present invention, a catalyst may or may not be used, but when a catalyst is used, the reaction rate can be increased. As the catalyst to be used,
Examples include metals of groups II, III, IV, and V of the periodic table, oxides thereof, salts thereof, and the like. Specifically, zinc dust,
Tin powder, metals such as aluminum, magnesium, titanium, germanium, metal oxides such as tin oxide, antimony oxide, zinc oxide, aluminum oxide, magnesium oxide, titanium oxide, stannous chloride, stannic chloride, bromide Metal halides such as monotin, 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 carboxylates 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 may be mentioned. In addition, organic metal oxides of the above metals such as dibutyltin oxide,
Alternatively, a metal alkoxide of the above metal such as titanium isopropoxide, an alkyl metal of the above metal such as diethylzinc, or an ion exchange resin such as Dowex or Amberlite can be used. The amount used is the aliphatic polyhydric alcohol and aliphatic polybasic acid used,
Or 0.0001 to 10% by weight of those oligomers
It is good, and considering economic efficiency, 0.001 to 2% by weight is preferable.

In the production method of the present invention, it is preferable to carry out in an inert gas atmosphere so that water does not enter from the outside of the system, and it may be carried out while substituting with an inert gas or bubbling with an inert gas. . In the production method of the present invention, the reaction can be carried out while distilling the water or monomer produced in the reaction with the organic solvent out of the reaction system, but preferably the produced water or monomer is distilled out of the reaction system with the organic solvent. In addition, the reaction can be carried out while charging the reaction system with an organic solvent having the same or low amount of water or a monomer as the water or the monomer dissolved in the distilled organic solvent, and a preferable example of the embodiment is a raw material monomer. As described below, 1,4-butanediol, succinic acid, and glycerin are used.

A water separator (eg Dean Stark)
In a reactor equipped with a trap), a solvent and a predetermined amount of 1,4
-Butanediol, succinic acid, glycerin and a certain amount of catalyst are charged, the reactor is heated and the water produced is distilled off and led to a water separator. Water having a solubility equal to or higher than the solubility of the solvent is separated by a water separator and removed outside the system, and the solvent containing water for the solubility is returned to the reaction system. At this stage, 1,4-butanediol, succinic acid and glycerin are oligomerized. The weight average molecular weight at this stage is 500 to 1,000, and the weight average molecular weight may be up to 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 another reactor in the absence of a solvent, without a catalyst, under reduced pressure, or with a solvent without a catalyst. As it is at the distillation temperature of the solvent,
Water generated as the reaction proceeds may be removed, and the reaction may be continued while returning the solvent saturated with water to the reaction system. However, if the reaction is performed for several hours, the weight average molecular weight of 15,000 to 50 depends on the kind of the solvent. 1,000 are obtained. To obtain a higher molecular weight polymer, after the water in the raw material is almost distilled, remove the water separator, attach a tube filled with a desiccant such as molecular sieve, and distill the solvent through this tube. Bring to reflux, treat distillate solvent in another reactor with desiccant and return to reactor, or charge new low water content solvent to reactor . The amount of water dissolved in the solvent is 50% by these methods.
The weight average molecular weight is 50,0 depending on the kind of the solvent, although the reaction is continued for several tens of hours as it is at the ppm or less.
It is possible to obtain a degradable polymer composition having an amount of 00 to 500,000. After the completion of the reaction, any treatment method may be used to obtain the desired degradable polymer composition.For example, chloroform is added to the reaction solution and heated, and then the mixture is discharged into methanol and the precipitated crystals are filtered and dried. Thus, a desired degradable polymer composition can be obtained.

The weight average molecular weight of the decomposable polymer composition obtained by the method of the present invention depends on the type of solvent, the type and amount of catalyst, the reaction temperature, the reaction time, the method of treating the solvent distilled by azeotropic distillation, and the like. A variety of compounds can be obtained by varying the amount, but it is about 15,000 to 500,000. In the method of the present invention, when the condensation reaction is carried out in the presence of a catalyst, if the catalyst remains in the polymer, the thermal stability and weather resistance of the polymer may be affected. Is preferred. A preferable removal method is a method in which a powdery solid polymer obtained by expanding the condensation reaction solution or cooling it as it is is contacted with an acidic substance in the presence of a hydrophilic organic solvent.

As the hydrophilic organic solvent used in this method, 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, N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethylimidazolidinone, hexamethylphosphoramide, and other amides. 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 paratoluenesulfonic acid. Particularly inexpensive hydrochloric acid, sulfuric acid,
Nitric acid and the like are preferred. 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 it is less than 0.0001 mol, the effect of removing the catalyst will be poor, and if it is more than 5.0 mol, problems such as deterioration of the polymer may occur.

The solid form of the polymer used in this method is in the form of powder, granules, granules, flakes or blocks. Generally, as a method for obtaining a polymer, the polymer is once converted into a good solvent by a conventional method. After dissolution, there is a method of dropping a poor solvent or dropping into a poor solvent, or a method of heating and dissolving in a specific solvent and then cooling and crystallizing.

The polymer preferably has a bulk density of 0.6 g / ml or less, more preferably 0.05 to 0.5 g / ml. Bulk density is 0.6g
If it is larger than / ml, the catalyst in the polymer may not be completely removed because the contact with the acidic substance becomes insufficient. On the contrary, if the bulk density is less than 0.05 g / ml, there is no problem in removing the catalyst. However, there is a case where an operational problem occurs due to poor filterability after the treatment. The conditions for bringing the polymer and the acidic substance into contact are preferably in a hydrophilic organic solvent, the solid content concentration is about 3 to 40% by weight, and the contact temperature is 0 to 1
00 ° C., particularly preferably 0 to 60 ° C., contact time 0.1
Time to about 24 hours, particularly preferably about 0.5 to 8 hours.

The polymer composition thus obtained has sufficient strength and toughness when processed into a film, a molded product or the like, and can be used as it is for applications such as containers.
In particular, when a polymer produced by the production method of the present invention is formed into a film, a polymer having a weight average molecular weight of less than 50,000 has insufficient tensile strength and elongation and is difficult to use as a film. for that reason,
When used as a film, the weight average molecular weight of this polymer is required to be 50,000 or more, preferably 70,000 or more, more preferably 10 in terms of strength and elongation.
Although a weight average molecular weight of 10,000 or more is required, the production method of the present invention can easily obtain an aliphatic polyester having a suitable molecular weight for use in this film. Furthermore, these high molecular weight aliphatic polyesters can be subjected to secondary processing such as stretching, blowing and vacuum forming. Therefore, the high molecular weight aliphatic polyester obtained by the method of the present invention can be used as a medical material or as a substitute for conventional general-purpose resins such as foams and nets.

[0029]

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

Example 1 41.0 g of 1,4-butanediol and 53.1 succinic acid
g, glycerin 0.78 g, and stannous oxide 0.77
g at 150 ° C./1 atm for 2.5 hours, then
The mixture was heated and stirred at 150 ° C./15 mmHg for 0.5 hours while flowing water out of the system to be oligomerized. To this, 232 g of orthodichlorobenzene was added, and a tube filled with 20 g of molecular sieve 5A was attached, so that the distilled solvent was returned to the reactor through the molecular sieve layer. Then, the reaction was carried out at 130 ° C./15 mmHg for 20 hours. 800 g of ortho-dichlorobenzene was added to the reaction mass, which was filtered while hot and then cooled for crystallization. This was filtered, and the filter cake was mixed with 1% hydrochloric acid / isopropyl alcohol solution 6
After adding 00 ml and expanding the mixture for 1 hour, suction filtration was performed to remove tin. After the filter cake was spread with 600 ml of isopropyl alcohol, suction filtration was performed until the filtrate became neutral, and then dried with hot air at 60 ° C., 63.
5 g (81%) of polyethylene succinate was obtained. The polyethylene succinate has a weight average molecular weight of 37.
It was 1,000.

Preparation of Film The obtained copolymer was hot pressed at a temperature of 170 ° C. to prepare a pressed film. The physical properties of the produced film are shown below. Thickness: 100 μm The tensile strength was measured according to JIS K-6732. Tensile strength: 330 kg / cm ² (yield) Elongation: 320% Melt tension (MT value) It was measured at a temperature of 160 ° C. and a load of 2160 g according to ASTM D-1238. Melt tension (MT value): 3.0 g Degradability When the prepared film was embedded in compost at 40 ° C., the shape disappeared in 2 weeks.

Comparative Example 1 41.0 g of 1,4-butanediol and 53.1 succinic acid
0.774 g of stannous oxide was added to g, and 150 ° C / 1at
m for 2.5 hours, and at 150 ° C./15 mmHg for 0.1 hour.
The mixture was heated and stirred for 5 hours while flowing water out of the system to carry out oligomerization. To this was added a tube filled with 232 g of ortho-dichlorobenzene and charged with 20 g of molecular sieve 5A so that the distilled solvent passed through the molecular sieve layer and returned to the reactor. After that, 110 ° C / 100mm
The reaction was carried out with Hg for 20 hours. 465g in the reaction mass
Ortho-dichlorobenzene was added for crystallization. 1% of filter cake
Add 600 ml of hydrochloric acid / isopropyl alcohol solution 1
After the time was extended, suction filtration was performed to remove tin. The filter cake was spread with 600 ml of isopropyl alcohol, and suction filtration was performed until the filtrate became neutral, and then dried with hot air at 60 ° C. to obtain 65.0 g (84%).
A copolymer of The weight average molecular weight of the obtained polymer was 125,000.

Preparation of Film The obtained copolymer was hot pressed at a temperature of 170 ° C. to prepare a pressed film. The physical properties of the produced film are shown below. Thickness: 100 μm The tensile strength was measured according to JIS K-6732. Tensile strength: 340 kg / cm ² (yield) Elongation: 420% Melt tension (MT value) Measured at a temperature of 160 ° C. and a load of 2160 g according to ASTM D-1238. Melt tension (MT value): 0.65 g Degradability When the prepared film was embedded in compost at 40 ° C, the shape disappeared in 2 weeks. Comparative Example 2 Using polyethylene (Mirason-11), temperature 170 ° C
Hot-pressed to make a press film. The physical properties of the produced film are shown below.

Thickness: 100 μm Tensile strength was measured according to JIS K-6732. Tensile strength: 220 kg / cm ² (yield) Elongation: 500% Degradability When this film was embedded in 40 ° C. compost, no change was observed even after 2 weeks.

[0035]

Industrial Applicability According to the production method of the present invention, an aliphatic ester which is useful as a biodegradable polymer and does not contain impurities is obtained by direct dehydration condensation from polyhydric alcohols, polybasic acids and trihydric or higher polyhydric alcohols. be able to. Further, according to the method of the present invention, it is possible to easily obtain a degradable polymer composition having excellent melt tension and having sufficient strength for molded articles such as foams and blow bottles and adhesives.

Front Page Continuation (72) Inventor Akihiro Yamaguchi 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (7)

[Claims] 1. A method of subjecting an aliphatic polyhydric alcohol or a mixture thereof and an aliphatic polybasic acid or a mixture thereof, or an oligomer or polymer thereof to a heat dehydration reaction together with at least one polyhydric alcohol having a valence of 3 or more. A method for producing a degradable polymer composition, which is characterized. 2. The method according to claim 1, wherein the polyhydric alcohol is an aliphatic diol. 3. The method according to claim 2, wherein the aliphatic diol is ethylene glycol. 4. The method according to claim 2, wherein the aliphatic diol is 1,4-butanediol. 5. The method according to claim 1, wherein the polybasic acid is an aliphatic dicarboxylic acid. 6. The method according to claim 5, wherein the aliphatic dicarboxylic acid is succinic acid. 7. An aliphatic polyester having a weight average molecular weight of 15,000 or more obtained by the method of claim 1.