JP2000053753A - Biodegradable polyester copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable polyester copolymer having excellent mechanical characteristics and thermal characteristics, exhibiting biodegradability and low moisture-permeability and applicable to wide application field and provide its production process and molded article. SOLUTION: The objective biodegradable polyester copolymer is composed of (A) 99.2-50 mol.% of a 2-hydroxy-2,2-dialkylacetic acid unit having same or different 1-5C alkyl groups and (B) one or more copolymer units selected from (a) a hydroxycarboxylic acid excluding 2-hydroxy-2,2-dialkylacetic acid, (b) a polybasic carboxylic acid and (c) a polyhydric alcohol. The weight-average molecular weight of the copolymer is 10 000-1,500,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to 2-hydroxy-
The present invention relates to a biodegradable polyester copolymer containing a 2,2-dialkylacetic acid unit as a main component.

[0002]

2. Description of the Related Art From the viewpoint of protection of the natural environment, the problem of plastic waste has been raised, and a polymer decomposable in the natural environment and a molded product thereof have been demanded. In recent years, studies on biodegradable synthetic polymers have been actively conducted, and it has been found that aliphatic polyesters are hydrolyzed by enzymes. However, although many of these aliphatic polyesters show biodegradability, the melting temperature is low,
Because of poor physical properties, it could not be used in a wide range of fields. On the other hand, as an aliphatic polyester having a high melting point,
Although 3-hydroxybutyrate, polyglycolide, polypivalolactone, and the like are known, these resins have poor heat stability at the time of melting and have a problem in moldability. Various attempts have been made to solve this problem, but when copolymerization is performed to impart moldability, the melting temperature tends to decrease, and the heat resistance tends to decrease.

[0003] Recently, polylactic acid resins having excellent mechanical and thermal properties and biodegradability have been attracting attention in an attempt to solve these physical problems.
For applications requiring low moisture permeability, such as food packaging materials and bottle containers, because the moisture permeability (moisture permeability) is too high, sufficient performance has not yet been obtained. On the other hand, polyesters in which a hydrophobic resin is imparted with hydrolyzability by introducing a small amount of a sulfonate group into an aromatic polyester have been disclosed (JP-A-5-507109, JP-A-5-507109).
JP-A-505040) has a problem that it is difficult to produce a uniform product because a slight difference in sulfonate group content has a large effect on fluctuations in water vapor permeability.

[0004] Incidentally, an analog of polylactic acid, which is an aliphatic polyester, poly-2-hydroxy-2,2-
It is known that dimethylacetic acid (poly-2-hydroxyisobutyric acid) has a higher melting point than polylactic acid and also has excellent mechanical strength (Die Makromol. Che).
m. , 145 p. 123 (1971)), and there are some disclosures about the production method (US Patent No. 2,8).
No. 11,511). However, nothing is shown about the biodegradability of the resin. On the other hand, Japanese Patent Laid-Open No. 7-1
No. 33344 describes a method for producing a polyhydroxycarboxylic acid using a hydroxycarboxylic acid containing at least lactic acid as a raw material, and describes that the method is useful as a biodegradable polymer. Nothing is specifically shown about the polymerization composition and biodegradability.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a copolymer which is excellent in mechanical properties and thermal properties, has biodegradability and low moisture permeability, and is adaptable to a wide range of uses. To provide.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that 2-hydroxy-
2,2-dialkylacetic acid unit as an essential constituent unit,
99.2-hydroxy-2,2-dialkylacetic acid units
The inventors have found that a polyester copolymer containing 50 mol% achieves the object, and have completed the present invention.
That is, the present invention relates to (1) (A) 2-hydroxy-alkyl having the same or different alkyl group having 1 to 5 carbon atoms
99.2 to 50 mol% of 2,2-dialkylacetic acid units
And (B) one or more selected from the group consisting of (a) hydroxycarboxylic acids other than 2-hydroxy-2,2-dialkylacetic acid, (b) polyvalent carboxylic acids and (c) polyvalent alcohols A biodegradable polyester copolymer having a weight-average molecular weight of 10,000 or more and 1,500,000 or less, (2) a carbon number of 1 2-hydroxy- consisting of the same or different alkyl groups
The average number of chains of 2,2-dialkylacetic acid units is 2 or more and 60
The following biodegradable polyester copolymer according to (1), (3) wherein the 2-hydroxy-2,2-dialkylacetic acid unit is 2-hydroxy-2,2-dimethylacetic acid (2-hydroxyisobutyric acid). (1) or the biodegradable polyester copolymer according to (2), (4) the biodegradable polyester copolymer according to (3), wherein the copolymerized unit is a hydroxycarboxylic acid unit, (5) (A) 2-hydroxy- consisting of the same or different alkyl groups having 1 to 5 carbon atoms
2,2-dialkylacetic acid monomer, its ester monomer,
Or a cyclic dimer thereof;

(B) (a) a hydroxycarboxylic acid monomer other than 2-hydroxy-2,2-dialkylacetic acid, its ester monomer and its cyclic dimer, and (b) a polyvalent carboxylic acid monomer And (c) copolymerizing one or more monomers selected from the group consisting of polyhydric alcohol monomers or cyclic dimers alternately and separately. (6) The method for producing a biodegradable polyester copolymer according to (6), (1), (2), (3) or (4).
(7) A sheet mainly comprising the biodegradable polyester copolymer according to (1), (2), (3) or (4). (8) A foam mainly comprising the biodegradable polyester copolymer according to (1), (2), (3) or (4).
(9) A fiber mainly comprising the biodegradable polyester copolymer according to (1), (2), (3) or (4).

Hereinafter, the present invention will be described in detail. The alkyl group in the 2-hydroxy-2,2-dialkylacetic acid unit in the present invention has 1 to 5 carbon atoms, and the two alkyl groups may be the same or different. . Specific examples of the 2-hydroxy-2,2-dialkylacetic acid unit include 2-hydroxy-2,2-dimethylacetic acid, 2-hydroxy-2,2-diethylacetic acid,
Hydroxy-2,2-di-n-propylacetic acid, 2-hydroxy-2,2-diisopropylacetic acid, 2-hydroxy-2,2-di-n-butylacetic acid, 2-hydroxy-2,
2-diisobutylacetic acid, 2-hydroxy-2,2-di-
t-butylacetic acid, 2-hydroxy-2,2-di-n-pentylacetic acid, 2-hydroxy-2-methyl-2-ethylacetic acid, 2-hydroxy-2-methyl-2-n-propylacetic acid, 2- Hydroxy-2-methyl-2-isopropylacetic acid, 2-hydroxy-2-methyl-2-n-butylacetic acid, 2-hydroxy-2-methyl-2-t-butylacetic acid, 2-hydroxy-2-methyl-2 -N-propylacetic acid, 2-hydroxy-2-methyl-2-n-pentylacetic acid, 2-hydroxy-2-ethyl-2-n-propylacetic acid, 2-hydroxy-2-ethyl-2-isopropylacetic acid, 2 -Hydroxy-2-ethyl-2-n-butylacetic acid, 2-hydroxy-2-ethyl-2-isobutylacetic acid, 2-hydroxy-2-ethyl-2-t-butylacetic acid, 2-hydroxy-2- Chill -2-n-pentyl acetate, 2-hydroxy -2-n-propyl-2-isopropyl acetate, 2-hydroxy -2-n-propyl -2-n
-Butylacetic acid, 2-hydroxy-2-n-propyl-2
-Isobutylacetic acid, 2-hydroxy-2-n-propyl-2-t-butylacetic acid, 2-hydroxy-2-n-propyl-2-n-pentylacetic acid, 2-hydroxy-2-isopropyl-2-n- Butyl acetic acid, 2-hydroxy-2
-Isopropyl-2-isobutylacetic acid, 2-hydroxy-2-isopropyl-2-t-butylacetic acid, 2-hydroxy-2-isopropyl-2-n-pentylacetic acid, 2-
Hydroxy-2-n-butyl-2-isobutylacetic acid, 2
-Hydroxy-2-n-butyl-2-t-butylacetic acid,
2-hydroxy-2-n-butyl-2-n-pentylacetic acid, 2-hydroxy-2-isobutyl-2-t-butylacetic acid, 2-hydroxy-2-isobutyl-2-n-pentylacetic acid, 2-hydroxy -2-t-butyl-2-n-
Pentyl acetic acid and the like.

The 2-hydroxy-2,2-dialkylacetic acid unit of the present invention is produced directly from 2-hydroxy-2,2-dialkylacetic acid or an ester thereof by dehydration or dealcoholation. ,
Alternatively, 2-hydroxy-2,2-dialkylacetic acid or an ester thereof can be dehydrated or converted to a cyclized dimer by dealcoholation, and the cyclic dimer can be produced by ring-opening polymerization. 2 used here
The ester of -hydroxy-2,2-dialkylacetic acid is 2
An ester of -hydroxy-2,2-dialkylacetic acid and an alcohol having 1 to 10 carbon atoms. Specific examples of the alcohol having 1 to 10 carbon atoms include methanol, ethanol, propanol, isopropanol,
Examples thereof include n-butanol, sec-butanol, t-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, and n-decanol. In the present invention, 2-hydroxy-2,2-dialkylacetic acids, 2-hydroxy-
Esters of 2,2-dialkylacetic acid with alcohols having 1 to 10 carbon atoms, and 2-hydroxy-2,2
-Cyclic dimers obtained by cyclizing and dimerizing dialkylacetic acid or its ester or the like by dehydration or dealcoholation are collectively referred to as 2-hydroxy-2,2-dialkylacetic acids.

[0010] In the polyester copolymer of the present invention,
Usually, the compound unit is the minimum repeating unit (monomer unit) forming the copolymer, with the exception of
When the copolymer units are bonded to each other, they are combined into one minimum repeating unit (monomer unit). For example, when a polyhydric alcohol unit and a polycarboxylic acid unit which are copolymer units are bonded adjacent to each other, the polyhydric alcohol unit and the polyvalent carboxylic acid unit are put together to form a minimum repeating unit ( Monomer unit). Also, when the polyhydric alcohols are bonded together, one minimum repeating unit (monomer unit)
And

It is necessary that the content of the 2-hydroxy-2,2-dialkylacetic acid unit comprising the same or different alkyl groups having 1 to 5 carbon atoms is 99.2 to 50 mol%. Preferably it is 98.5-80 mol%.
If it is less than 50 mol%, the moisture permeability of the obtained polyester copolymer will be large, and if it exceeds 99.2 mol%, biodegradability will not be obtained. Also, 2-hydroxy-2,2
The average number of dialkylacetic acid units is preferably 2 or more and 60 or less. More preferably, it is 5 or more and 30 or less. When the average number of chains exceeds 60, the biodegradability becomes extremely slow, and when it is less than 2, the moisture permeability of the polyester copolymer becomes large.

The 2-hydroxy-2,2-dialkylacetic acid or its ester, which is a raw material of the polyester copolymer of the present invention, is obtained, for example, by reacting a ketone with hydrocyanic acid to produce cyanohydrin, and then adding water or alcohols and It can be produced by converting a nitrile group into a carboxyl group or an ester group in the presence of sulfuric acid.
As a specific example, when acetone is used as a ketone, 2-hydroxy-2,2-dimethylacetic acid (2-hydroxyisobutyric acid) or an ester thereof can be produced via acetone cyanohydrin. . As the ketone, acetone, methyl ethyl ketone, and the like, which are industrially easily available, are preferably used. Therefore, as the 2-hydroxy-2,2-dialkylacetic acid, 2-hydroxy-2,2-dimethylacetic acid (2-hydroxyisobutyric acid) or an ester thereof, 2-hydroxy-2-ethyl-2-methylacetic acid (2 -Hydroxy-2-methylbutyric acid) or an ester thereof is preferred. In particular, acetone is industrially available at low cost, and methyl methacrylate, which is a raw material of methacrylic resin, is industrially produced using cyanohydrin obtained by reacting acetone and hydrocyanic acid as an intermediate raw material. In consideration of the above, a polyester obtained from 2-hydroxy-2,2-dimethylacetic acid (2-hydroxyisobutyric acid) or an ester thereof which can be co-produced is particularly preferable.

The copolymer of the present invention comprises (a) a hydroxycarboxylic acid unit excluding a 2-hydroxy-2,2-dialkylacetic acid unit, (b) a polyhydric alcohol unit, (c) a polyvalent carboxylic acid unit, d) It contains more than 0.8 mol% and less than 50 mol% of repeating units selected from units in which a polyhydric alcohol unit and a polyhydric carboxylic acid unit are bonded adjacent to each other. The hydroxycarboxylic acid unit, polyvalent carboxylic acid unit and polyhydric alcohol unit are 2-hydroxy-
It is preferably used because it has excellent compatibility with 2,2-dialkylacetic acid units and the resulting polyester copolymer becomes uniform. One of the above-described hydroxycarbonic acid units, polycarboxylic acid units, and polyhydric alcohol units may be used alone, or two or more may be used in combination.

(A) The hydroxycarboxylic acid unit excluding the 2-hydroxy-2,2-dialkylacetic acid unit includes:
A unit having a carbon number of 2 to 30 is preferable, for example, a unit having a hydroxyl group at the 2-position such as 2-hydroxyacetic acid (glycolic acid), 2-hydroxy-2-methylacetic acid (lactic acid), or 2-hydroxy-2-butyric acid. Or a unit having a hydroxyl group at the 3-position, such as 3-hydroxypropionic acid, 3-hydroxybutyric acid, and 3-hydroxyvaleric acid;
Examples include units having a hydroxyl group at the 4-position, such as hydroxybutyric acid. Examples of the raw material for these units include a corresponding hydroxycarboxylic acid, an ester of the corresponding hydroxycarboxylic acid and the alcohol having 1 to 10 carbon atoms, and a compound capable of forming a cyclic dimer is a cyclic dimer of the corresponding compound. Body, for example, β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-
Lactones such as caprolactone, for example, glycolide,
D-form, L-form or D / L-form lactide can be used. Hereinafter, these are collectively abbreviated as hydroxycarboxylic acids. In the copolymer according to the present invention, one type of these hydroxycarbonic acid units may be used alone, or two or more types may be used in combination.

(B) The polyvalent carboxylic acid unit is preferably a divalent or trivalent carboxylic acid unit having 2 to 20 carbon atoms. For example, oxalic acid, malonic acid, glutaric acid, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, fumaric acid, maleic acid, 1,4-cyclohexanedicarboxylic acid And aliphatic dicarboxylic acid compounds such as phthalic acid, isophthalic acid and terephthalic acid, and tricarboxylic acid units such as propanetricarboxylic acid, trimellitic acid and pyromellitic acid. In these cases, the raw materials of the polycarboxylic acid unit include a corresponding polycarboxylic acid, an ester of the corresponding polycarboxylic acid and the alcohol having 1 to 10 carbon atoms, and a corresponding polycarboxylic anhydride. Can be used. Among these, when a tricarboxylic acid unit is introduced as a polyvalent carboxylic acid unit, not only a high molecular weight polyester can be obtained, but also the obtained polyester becomes a branched polymer,
Melt viscoelasticity is improved, and it tends to be easily formed into a film, foam, or the like. Hereinafter, these polycarboxylic acids are collectively referred to as polycarboxylic acids. In the copolymer of the present invention, as the polycarboxylic acid unit,
One type may be used alone, or two or more types may be used in combination.

The (c) polyhydric alcohol unit used in the present invention preferably has 2 to 20 carbon atoms. For example,
Ethylene glycol, 1,3-propanediol, 1,
2-propanediol, 1,4-butanediol, 2,
3-butanediol, 1,5-pentanediol, 1,
8-octanediol, 1,10-decanediol,
1,12-dodecanediol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,3-
Examples include aliphatic diol units such as cyclohexanediol, diethylene glycol, and triethylene glycol, glycerin, pentaerythritol, and butane-1,2,3-triol units. As a raw material of these polyhydric alcohol units, corresponding polyhydric alcohols can be used. Of these, as a polyhydric alcohol unit, 3
When a divalent alcohol unit is introduced, not only a high molecular weight polyester can be obtained, but also the obtained polyester becomes a branched polymer, so that the melt viscoelasticity is improved, and it is easy to process into a film, a foam, and the like. Tend. Hereinafter, these are abbreviated as polyhydric alcohols. In the copolymer of the present invention, as the polyhydric alcohol unit, one type may be used alone, or two or more types may be used in combination.

Further, as a special case, a polyoxyalkylene glycol in which polyhydric alcohols are bonded to each other and have hydroxyl groups at both ends of the molecular chain, as described above as an exception where the compound unit is not the minimum repeating unit,
For example, polyhydric alcohol units such as polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyoxyhexamethylene glycol, and polyoxyethylene polyoxypropylene glycol block polymers are also the copolymerized units of the present invention. (C) contained in a polyhydric alcohol unit; The number average molecular weight of the polyoxyalkylene glycol is 50,000
It is preferably 0 or less. If it exceeds 50,000, problems tend to occur in the polymerizability at the time of polycondensation.

The method for producing the polyester copolymer of the present invention will be described below. Here, 2-hydroxy-2,2-
A polymer obtained by previously polymerizing dialkylacetic acids is referred to as a prepolymer. Further, a group consisting of hydroxycarboxylic acids, polycarboxylic acids, and polyhydric alcohols is referred to as a compound group for copolymerization, and a compound belonging to the group is referred to as a compound for copolymerization. Further, an oligomer composed of one compound for copolymerization selected from the group of compounds for copolymerization, or an oligomer composed of two or more compounds for copolymerization is referred to as a preliminary copolymerized oligomer.

The biodegradable polyester copolymer of the present invention can be produced in the presence or absence of a solvent, in the presence or absence of a catalyst. As a production method, a 2-hydroxy-2,2-dialkylacetic acid and one or more copolymerization compounds contained in the copolymerization compound group are directly polymerized by a dehydration or dealcoholization reaction. Method for producing, method for producing by polymerizing 2-hydroxy-2,2-dialkylacetic acids and pre-copolymerized oligomers, copolymerization of one or more kinds included in pre-polymerized product and compound group for copolymerization And a method of polymerizing a pre-polymerized product with a pre-copolymerized oligomer.

The method of adding the substances deposited in the polymerization at the time of polymerization includes (i) 2-hydroxy-2,2-dialkylacetic acids and / or a prepolymer, a compound for copolymerization and / or a precopolymerized oligomer. And (ii) sequentially or continuously adding a compound for copolymerization and / or a pre-copolymerized oligomer to 2-hydroxy-2,2-dialkylacetic acids and / or a pre-polymerized product. (Iii) adding a 2-hydroxy-2,2-dialkylacetic acid and / or a prepolymer sequentially or continuously to a compound for copolymerization and / or a precopolymerized oligomer. A method of copolymerizing (iv) 2
-Hydroxy-2,2-dialkylacetic acids and / or a prepolymer and a compound for copolymerization and / or a precopolymerized oligomer are alternately added and copolymerized.

Among these methods, the (iv) 2-hydroxy-2,2-dialkylacetic acid and / or the prepolymer and the copolymerization compound and / or the precopolymerized oligomer are alternately added. The method of copolymerization is preferred. Furthermore, the method of alternately adding a prepolymer of 2-hydroxy-2,2-dialkylacetic acid and a pre-copolymerized oligomer requires preliminarily polymerizing the additive. Since it is necessary to carry out, industrially, a method of copolymerizing while adding alternately 2-hydroxy-2,2-dialkylacetic acids and a compound for copolymerization is most preferable.

The reason that the method of (iv) copolymerization while alternately adding a 2-hydroxy-2,2-dialkylacetic acid and a compound for copolymerization is particularly preferable as described above,
If the average number of chains of the hydroxy-2,2-dialkylacetic acid unit is long, that is, if it exceeds 60, the biodegradability will be extremely slow. Specifically, 2-hydroxy-2,2
(I) (ii) or (iii) when a copolymerization compound having a polymerization rate significantly different from that of dialkylacetic acids is polymerized.
The addition of only one of them at a time or only one of them results in a long average chain number, that is, a block polymer, and the biodegradability of the biodegradable polyester targeted by the present invention is extremely low. For example, when 2-methyl-2,2-dimethylacetic acid as 2-hydroxy-2,2-dimethylacetic acid is copolymerized with tetramethyl glycolide, which is a cyclic dimer, and ε-caprolactone as a compound for copolymerization, The polymerization rate of tetramethyl glycolide is much higher than that of ε-caprolactone, the average number of 2-hydroxy-2,2-dimethylacetic acid units becomes longer, and the polyester becomes extremely slow in biodegradability. . In the case of these combinations, tetramethyl glycolide and ε-
Preferably, caprolactone is added alternately.

In the polymerization, when a 2-hydroxy-2,2-dialkylacetic acid is used as a monomer, the polymerization can be carried out without a catalyst. However, the use of a catalyst usually increases the reaction rate. be able to. Examples of the catalyst that can be used in the present invention include:
Group II, III, IV, V metals, metal salts, metal oxides, metal hydroxides. For example, titanium, zirconium, niobium, tungsten, zinc, germanium, tin, antimony and other metals, titanium oxide, zinc oxide,
Metal oxides such as silica, alumina, tin oxide, antimony oxide, tin fluoride, antimony fluoride, magnesium chloride, aluminum chloride, zinc chloride, stannous chloride, stannic chloride,
Metal salts such as stannous bromide, stannic bromide, aluminum sulfate, zinc sulfate, tin sulfate, magnesium carbonate, calcium carbonate, zinc carbonate, lithium hydroxide, sodium hydroxide,
Metals such as potassium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, aluminum hydroxide, zirconium hydroxide, iron hydroxide, cobalt hydroxide, nickel hydroxide, copper hydroxide and zinc hydroxide Hydroxides, aluminum acetate, zinc acetate, tin acetate, octane tin, tin stearate, organic carboxylate such as iron lactate, tin lactate, tetraethoxy titanium, tetrabutyl titanium, tetraisopropyl titanium, acetylacetone titanium, dibutyl tin oxide, etc. Organic metal, organic sulfonic acid salts such as tin methanesulfonate, tin trifluoromethanesulfonate, tin p-toluenesulfonate, lithium t-
Butocide, Sodium methoxide, Potassium t
Metal alkoxides of the above metals such as butoxide, tetraethoxygermanium, tetra-n-butoxygermanium, etc., organic sulfonic acids such as methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, amberlite, dowex, etc. Ion exchange resins and the like.

When a catalyst is used, these catalysts may be used alone or in a combination of two or more. The amount of these catalysts to be used is usually 10 ⁻⁷ to 10 ⁻⁷ , based on the total weight of the raw materials used, regardless of the polymerization mode.
The range is 5% by weight, preferably 10 ^{-6 -6 to} 3% by weight, more preferably 10 ^{-5 to} 0.5% by weight. Organic solvents used in the polymerization include cyclohexane, benzene, toluene, xylene, mesitylene, biphenyl, naphthalene, hydrocarbons such as tetralin, dichloromethane, chloroform, 1,2-dichloroethane, 1,1,
2-trichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, o-dichlorobenzene, m-
Halogen solvents such as dichlorobenzene, p-dichlorobenzene, trichlorobenzene, bromobenzene and iodobenzene; ketone solvents such as 2-butanone, 3-hexanone, acetophenone and benzophenone; tetrahydrofuran; 1,3-dioxolan; , 4-dioxane,
1,3-dioxane, trioxane, dimethoxymethane, 2-methoxyethyl ether, ethylene glycol dimethyl ether, dibutyl ether, anisole, phenetole, o-dimethoxybenzene, m-dimethoxybenzene, p-dimethoxybenzene, ethoxybenzene, butoxybenzene, pen Toxibenzene, 2-chloromethoxybenzene, 2-bromomethoxybenzene, 4
-Chloromethoxybenzene, 4-bromomethoxybenzene, 2,4-dichloromethoxybenzene, 3-methoxytoluene, diphenyl ether, dibenzyl ether,
Benzylphenyl ether, methoxynaphthalene, 1-
Ether solvents such as chloronaphthalene and the like, dimethylformamide, dimethylsulfoxide, sulfolane, pyridine, pyrimidine, aniline and the like can be mentioned.

At the time of polymerization, a heat stabilizer can be added in order to suppress coloring due to thermal deterioration of the copolymer. . The polyester copolymer of the present invention may have a hydroxyl group at a terminal or may be subjected to an esterification treatment by reacting with an acid anhydride such as acetic anhydride after the polymerization reaction. The thus obtained polyester having 2-hydroxy-2,2-dialkylacetic acid units has a weight average molecular weight of 10.0.
00 to 1,500,000, preferably 1,000
It is less than 000, more preferably less than 500,000. If it is less than 10,000, the strength is low and lacks practicality. The higher the weight average molecular weight, the better, but 1,5
If it exceeds 00,000, molding becomes difficult.

The polyester copolymer of the present invention thus obtained is melted to obtain a molded product such as a molded container,
It can be processed into sheets (films), foams, fibers and the like. If necessary, heat treatment or the like can be performed after molding. Examples of molded articles such as molded containers include beverages and cosmetics bottles, disposable cups, trays and other containers, agricultural flower pots and growing floors, and building materials and civil engineering materials such as pipes and temporary fixing materials that need not be dug out. Is mentioned. Examples of the sheet (film) include a packaging film, an agricultural multi-film, a shopping bag, various tapes, and a fertilizer bag. As the foam, for example, it can be used as a food tray, a buffer, a heat insulating material, and the like. As the fiber, for example, a fishing line, a fishing net, a nonwoven fabric and the like can be used. In addition, as a special example, it can be used as a compounding agent such as a slow-acting fertilizer by being mixed with a fertilizer.

In obtaining a molded article from the copolymer of the present invention, various additives can be used. Additives include matting agents, carbon black, pigments for coloring, hindered amines, hindered phenols,
Examples of additives generally used in general-purpose polymers, such as an antioxidant such as a phosphoric acid type, an ultraviolet absorber such as a benzophenone type and a benzotriazole type, a release agent, a lubricant, a plasticizer, and the like. Two or more of these can be used in combination. The polyester copolymer of the present invention can be used by mixing with other polymers, natural materials such as starch and wood flour, and inorganic substances as required. Mixing adjustment of the copolymer of the present invention and various additives, natural materials, inorganic substances, etc., is usually a mixer used for adjusting the composition of the thermoplastic resin, for example, a ball mill, a paint shaker, a sand mill,
The mixture can be homogeneously mixed using a mixer such as a jet mill, a three-roll mill or a kneader.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
The properties of the copolymer were measured as follows. The content of the monomer unit constituting the copolymer: The content of the monomer unit forming the copolymer was measured by 1H-NMR at 400 MHz using heavy chloroform as a solvent, and the obtained result was analyzed. The number of monomer units relative to the total number of monomer units was calculated in mol%. Average number of 2-hydroxy-2,2-dialkylacetic acid units: 1 at 100 MHz using heavy chloroform as a solvent
3C-NMR measurement was performed by the NOE elimination 1H complete decoupling method, and the obtained result was analyzed and calculated for the diad chain distribution.・ Measurement of weight average molecular weight, using chloroform as solvent,
It was measured by gel permeation chromatography (column temperature 40 ° C.) using monodisperse polystyrene of known molecular weight as a standard substance. The melting temperature was measured at a heating rate of 10 ° C./min using DSC-7 (differential scanning calorimeter) manufactured by PerkinElmer. -Biodegradability of polyester copolymer: ISO DIS1
Performed according to 4855.

As a test piece (molded product for test) for tensile test, heat deformation temperature measurement and moisture permeability measurement, although it depends on the melting point of the resin, the temperature is 180 to 220 ° C. and the pressure is 100 kg / c.
Press molding was performed for 8 minutes at m ² to form a molded body having a thickness of 3 mm. -The tensile strength was measured at a test speed of 5 mm / min using a No. 1 test piece as a sample in accordance with JIS-K7127.・ Measurement of heat deformation temperature is 5mm x 5
A test piece having a thickness of 3 mm and a thickness of 3 mm was cut out into a sample, and the sample was measured at a heating rate of 10 ° C./min using a TMA-7 (thermomechanical analyzer) manufactured by PerkinElmer (provided that the bottom area was 1 mm).
² of the needle tip infested at a rate 100 mN / m ^2, and the temperature at which the 1mm penetration and heat distortion temperature). The measurement of the moisture permeability coefficient is performed at 25 ° C. according to the moisture permeability test method (cup method) of the moisture-proof packaging material specified in JIS-Z0208.
It was measured at a humidity of 90%.

[0030]

[Reference Example 1] 75% of 90% L-lactic acid at 130 ° C./50 m
After heating and stirring while removing water from the system at mHg for 3 hours, 325 g of diphenyl ether and 0.4 g of tin powder were added thereto.
Was added, and a tube filled with 75 g of molecular sieve 3A was attached, and the solvent distilled off under reflux was returned to the system through the molecular sieve, and the mixture was heated at 130 ° C./50.
The reaction was performed at mmHg for 30 hours. After completion of the reaction, 400 ml of chloroform was added to the reaction product to dissolve it, followed by suction filtration to remove tin. The obtained chloroform solution was added to 1500 ml of methanol, and the precipitated polylactic acid was separated by filtration and dried.

[0031]

EXAMPLE 1 500 g of 2-hydroxy-2,2-dimethylacetic acid (2-hydroxyisobutyric acid), 50 g of p-toluenesulfonic acid and 1 liter of toluene were placed in a 2 liter reactor equipped with a stirrer and Dean stack. The mixture was heated under reflux for 50 hours under nitrogen to perform a dehydration reaction. At this time, the mixture of refluxing toluene and product water is
The mixture was separated in Dean Stack and the aqueous layer was sequentially extracted. After completion of the reaction, the reaction solution is washed with cold water, further with a 10% aqueous sodium hydrogen carbonate solution, and finally with cold water, dried over anhydrous sodium sulfate and concentrated. Thereafter, the cyclic dimer was collected by distillation, and recrystallized and purified with an equal weight of toluene to obtain 100 g of a cyclic dimer (tetramethyl glycolide).

After sufficiently replacing the two-necked flask equipped with a condenser with nitrogen, 0.40 g of tetramethyl glycolide, 0.028 g of lithium-t-butoxide, 750 ml of xylene purified by dehydration distillation under a nitrogen atmosphere, and a stirrer bar And the polymerization is continued for 5 minutes while stirring at 130 ° C. Thereafter, a polymerization reaction was performed according to the following procedure.
Under a nitrogen atmosphere, 0.040 g of ε-caprolactone purified by dehydration distillation is added, and polymerization is continued for 5 minutes. Next, 0.40 g of tetramethyl glycolide is added, and polymerization is performed for 5 minutes. This series of operations (e-caprolactone and tetramethyl glycolide were alternately added) was continued 149 times. After the completion of the polymerization reaction, the polymer was added to 1,000 g of acetic anhydride and refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature, the precipitated polymer was filtered,
After washing with a large amount of methanol, the resultant was separated by filtration and dried to obtain 62 g of a white polymer. Molecular weight of the obtained copolymer, 1H-N
The content of 2-hydroxy-2,2-dimethylacetic acid units calculated from MR, the average number of chains of 2-hydroxy-2,2-dimethylacetic acid units calculated from 13C-NMR, moisture permeability coefficient, and tensile strength were measured. Table 1 shows the results. FIG. 1 shows a 13C-NMR chart of a copolymer which is usually measured. Biodegradability was confirmed in this polymer.

[0033]

Example 2 Tetramethyl glycolide was obtained in the same manner as in Example 1. After sufficiently replacing the two-necked flask equipped with a cooling tube with nitrogen, 0.40 g of tetramethyl glycolide, 0.028 g of lithium-t-butoxide, 750 ml of xylene purified by dehydration distillation under a nitrogen atmosphere, and a stir bar were charged. The polymerization is continued for 5 minutes while stirring at 130 ° C. Thereafter, a polymerization reaction was performed according to the following procedure.
Under a nitrogen atmosphere, 0.040 g of ε-caprolactone purified by dehydration distillation is added, and polymerization is continued for 5 minutes. Next, 0.40 g of tetramethyl glycolide is added, and polymerization is performed for 5 minutes. This series of operations (e-caprolactone and tetramethyl glycolide were alternately added) was continued 149 times. After the completion of the polymerization reaction, the solvent was distilled off, the residue was dissolved in 500 ml of chloroform, and purified by reprecipitation with 4000 ml of methanol. It was separated by filtration and dried to obtain 63 g of a white polymer. The molecular weight of the obtained copolymer, the content of 2-hydroxy-2,2-dimethylacetic acid unit calculated from 1H-NMR, and the content of 2-hydroxy-2, calculated from 13C-NMR.
Table 1 shows the results of measuring the average number of chains, the moisture permeability coefficient, and the tensile strength of the 2-dimethylacetic acid unit. Biodegradability was confirmed in this polymer.

[0034]

Example 3 Tetramethyl glycolide was obtained in the same manner as in Example 1. After sufficiently replacing the two-necked flask equipped with a cooling tube with nitrogen, 1.00 g of tetramethyl glycolide, 0.028 g of lithium-t-butoxide, 750 ml of xylene purified by dehydration distillation under a nitrogen atmosphere, and a stir bar were charged. The polymerization is continued for 15 minutes while stirring at 130 ° C. Thereafter, a polymerization reaction was performed according to the following procedure. Under a nitrogen atmosphere, 0.120 g of ε-caprolactone purified by dehydration distillation is added, and polymerization is continued for 15 minutes.
Then, 1.00 g of tetramethyl glycolide was added,
The polymerization is carried out for 5 minutes. This series of operations (e-caprolactone and tetramethyl glycolide were alternately added) was continued 49 times. After the completion of the polymerization reaction, the polymer was added to 1,000 g of acetic anhydride and refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature, the precipitated polymer was filtered,
After washing with a large amount of methanol, the resultant was separated by filtration and dried to obtain 48 g of a white polymer. Molecular weight of the obtained copolymer, 1H-N
The content of 2-hydroxy-2,2-dimethylacetic acid units calculated from MR, the average number of chains of 2-hydroxy-2,2-dimethylacetic acid units calculated from 13C-NMR, moisture permeability coefficient, and tensile strength were measured. . Table 1 shows the results. Biodegradability was confirmed in this polymer.

[0035]

Example 4 Tetramethyl glycolide was obtained in the same manner as in Example 1. After sufficiently replacing the two-necked flask equipped with a cooling tube with nitrogen, 1.81 g of tetramethyl glycolide, 0.028 g of lithium-t-butoxide, 750 ml of xylene purified by dehydration distillation under a nitrogen atmosphere, and a stir bar were charged. The polymerization is continued for 25 minutes while stirring at 130 ° C. Thereafter, a polymerization reaction was performed according to the following procedure. Under a nitrogen atmosphere, 0.49 g of ε-caprolactone purified by dehydration distillation is added, and polymerization is continued for 10 minutes. Then, 1.81 g of tetramethyl glycolide was added, and 2
The polymerization is carried out for 5 minutes. This series of operations (addition of ε-caprolactone and tetramethyl glycolide alternately) was continued 25 times, and finally 0.49 g of ε-caprolactone was added, followed by polymerization for 10 minutes. After the completion of the polymerization reaction, the solvent was distilled off, the residue was dissolved in 500 ml of chloroform, and purified by reprecipitation with 4000 ml of methanol. Filtration and drying yielded 50 g of a white polymer. Molecular weight of the obtained copolymer, 1H
Content of 2-hydroxy-2,2-dimethylacetic acid unit calculated from -NMR, 2-calculated from 13C-NMR
Average number of chains of hydroxy-2,2-dimethylacetic acid units,
The moisture permeability coefficient and the tensile strength were measured. Table 1 shows the results. Biodegradability was confirmed in this polymer.

[0036]

Comparative Example 1 Tetramethyl glycolide was obtained in the same manner as in Example 1. After sufficiently replacing the two-necked flask equipped with a condenser with nitrogen, 57.62 g of tetramethyl glycolide, 0.028 g of lithium-t-butoxide, 750 ml of xylene purified by dehydration distillation under a nitrogen atmosphere, and a stir bar were charged. The polymerization is continued for 5 hours while stirring at 130 ° C. Thereafter, under a nitrogen atmosphere, 0.080 g of ε-caprolactone purified by dehydration distillation is added, and polymerization is continued for 10 minutes. Then, tetramethyl glycolide 5
7.62 g was added and polymerization was carried out for 5 hours. After the completion of the polymerization reaction, the polymer was added to 1,000 g of acetic anhydride and refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature, the precipitated polymer was filtered, washed with a large amount of methanol, and then separated by filtration and dried to obtain 100 g of a white polymer. Molecular weight of the obtained copolymer 2 calculated from 1H-NMR
-Hydroxy-2,2-dimethylacetic acid unit content, 1
The average chain number, moisture permeability coefficient, and tensile strength of the 2-hydroxy-2,2-dimethylacetic acid unit calculated from 3C-NMR were measured. Table 1 shows the results. Biodegradability was not confirmed in this polymer.

[0037]

Comparative Example 2 Tetramethyl glycolide was obtained in the same manner as in Example 1. After sufficiently replacing the 200 ml pressure bottle with nitrogen, 55.0 g of tetramethyl glycolide, lithium-t
0.028 g of butoxide was charged and polymerization was carried out at 130 ° C. for 10 hours while shaking. After the completion of the polymerization reaction, the polymer was added to 1,000 g of acetic anhydride and refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature, the precipitated polymer was filtered, washed with a large amount of methanol, and then separated by filtration and dried to obtain 48 g of a white polymer. Molecular weight of the obtained copolymer, content of 2-hydroxy-2,2-dimethylacetic acid unit calculated from 1H-NMR, 13C-NMR
The average number of chains, moisture permeability coefficient, and tensile strength of the 2-hydroxy-2,2-dimethylacetic acid unit calculated from the calculated values were measured. Table 1 shows the results. Biodegradability was not confirmed in this polymer.

[0038]

Example 5 Tetramethyl glycolide was obtained in the same manner as in Example 1. After sufficiently replacing the two-necked flask equipped with a cooling tube with nitrogen, 0.13 g of tetramethyl glycolide, 0.028 g of lithium-t-butoxide, 750 ml of xylene purified by dehydration distillation under a nitrogen atmosphere, and a stir bar were charged. The polymerization is continued for 2 minutes while stirring at 130 ° C. Thereafter, a polymerization reaction was performed according to the following procedure.
Recrystallization purification was performed with toluene under a nitrogen atmosphere (3.
0.030 g of (S, 6S)-(-)-3,6-dimethyl-1,4-dioxane-2,5-dione (hereinafter abbreviated as L-(-)-lactide) is added, and polymerization is continued for 5 minutes. . Then, 0.13 g of tetramethyl glycolide was added, and 2
Polymerize for minutes. This series of operations (addition of L-(-)-lactide and tetramethyl glycolide alternately) was carried out at 350
Continued times. After the completion of the polymerization reaction, the polymer was added to 1,000 g of acetic anhydride and refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature, the precipitated polymer was filtered, washed with a large amount of methanol, and then separated by filtration and dried to obtain 46 g of a white polymer. In the usual measurement 13C-NMR of ester carbon in the copolymer, the chemical shift δ = 16
Peaks at 7.4 ppm, 167.6 ppm and 177.7 ppm were confirmed. Of these, δ = 167.4 pp
m and 167.6 ppm are poly 2-hydroxy-2,2
Ester carbon of dimethyl acetic acid homopolymer (δ = 17
7.7 ppm) and the ester carbon (δ = 167.2 ppm) of the polylactic acid homopolymer. Molecular weight of the obtained copolymer, content of 2-hydroxy-2,2-dimethylacetic acid unit calculated from 1H-NMR, 2-hydroxy- calculated from 13C-NMR
The average number of chains of 2,2-dimethylacetic acid units, moisture permeability coefficient, and tensile strength were measured. Table 1 shows the results. Biodegradability was confirmed in this polymer.

[0039]

Example 6 Tetramethyl glycolide was obtained in the same manner as in Example 1. After sufficiently replacing the two-necked flask equipped with a cooling tube with nitrogen, 50.0 g of tetramethyl glycolide, 0.028 g of lithium-t-butoxide, and recrystallization purification with toluene under a nitrogen atmosphere were performed. -Lactide 1
0.50 g was charged and polymerization was carried out at 130 ° C. for 10 hours. After completion of the reaction, the polymer was added to 1,000 g of acetic anhydride and refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature, the precipitated polymer was filtered, washed with a large amount of methanol, and separated by filtration to obtain 53 g of a white polymer. Molecular weight of the obtained copolymer, content of 2-hydroxy-2,2-dimethylacetic acid unit calculated from 1H-NMR, 2-hydroxy- calculated from 13C-NMR
The average number of chains of 2,2-dimethylacetic acid units, moisture permeability coefficient, and tensile strength were measured. Table 1 shows the results. Biodegradability was confirmed in this polymer.

[0040]

Comparative Example 3 Tetramethyl glycolide was obtained in the same manner as in Example 1. After sufficiently replacing the two-necked flask equipped with a cooling tube with nitrogen, 20.00 g of tetramethyl glycolide, 0.014 g of lithium-t-butoxide, 750 ml of dehydrated and distilled purified xylene in a nitrogen atmosphere, and a stir bar were charged. The polymerization is continued for 3.5 hours while stirring at 130 ° C. Thereafter, 0.050 g of L-(-)-lactide purified by recrystallization with toluene under a nitrogen atmosphere.
And continue the polymerization for 5 minutes. Next, 20.00 g of tetramethyl glycolide was added, and polymerization was carried out for 3.5 hours. After the completion of the polymerization reaction, the polymer was added to 1,000 g of acetic anhydride and refluxed for 1 hour under a nitrogen atmosphere.
After cooling at room temperature, the precipitated polymer was filtered, washed with a large amount of methanol, and then separated by filtration and dried to obtain 36 g of a white polymer. Molecular weight of the obtained copolymer, 1H-NMR
The content of the 2-hydroxy-2,2-dimethylacetic acid unit calculated from the above, the average number of chains of the 2-hydroxy-2,2-dimethylacetic acid unit calculated from 13C-NMR, the moisture permeability coefficient, and the tensile strength were measured. Table 1 shows the results. Biodegradability was not confirmed in this polymer.

[0041]

Embodiment 7 50 equipped with a jacket, a distilling pipe and an introducing pipe
After sufficiently replacing the 0 ml glass-lined tank reactor with nitrogen, 2-hydroxy-2, which was dehydrated and purified under nitrogen, was used.
100 g of 2-dimethylacetic acid methyl ester, and 19.3 ε-caprolactone similarly dehydrated and purified under nitrogen.
g, 0.0014 g of lithium-t-butoxide, 250 ml of benzene purified by dehydration and distillation in a nitrogen atmosphere, and a stirrer bar.
Continued for hours. At that time, the reaction was performed while continuously supplying the same amount of dehydrated and purified benzene as the distilled benzene to the system. After the completion of the polymerization reaction, benzene was distilled off, and the polymer was taken out, added to 1,000 g of acetic anhydride, and refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature,
The precipitated polymer was filtered, washed with a large amount of methanol, and separated by filtration to obtain 115 g of a white polymer. The molecular weight of the obtained copolymer, 2-, calculated from 1H-NMR
Hydroxy-2,2-dimethylacetic acid unit content, 13
The average number of chains, moisture permeability coefficient, and tensile strength of the 2-hydroxy-2,2-dimethylacetic acid unit calculated from C-NMR were measured. Table 1 shows the results. Biodegradability was confirmed in this polymer.

[0042]

Embodiment 8 50 equipped with a jacket, a distilling pipe and an introducing pipe
After sufficiently replacing the 0 ml glass-lined tank reactor with nitrogen, 2-hydroxy-2, which was dehydrated and purified under nitrogen, was used.
100 g of methyl 2-dimethylacetate (α-hydroxyisobutyrate), 10.1 g of methyl L-(−)-lactate which was similarly dehydrated and purified under nitrogen, lithium-
The reaction was continued for 220 hours while 0.0014 g of t-butoxide, 250 ml of benzene purified by dehydration distillation under a nitrogen atmosphere, and a stirrer bar were charged, and benzene and methanol produced as a by-product were azeotroped at a jacket temperature of 95 ° C.
At that time, the reaction was performed while continuously supplying the same amount of dehydrated and purified benzene as the distilled benzene to the system. After the polymerization reaction was completed, benzene was distilled off, and the polymer was taken out.
In addition to 000 g of acetic anhydride, the mixture was refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature, the precipitated polymer was filtered, washed with a large amount of methanol, and then separated by filtration and dried to obtain 107 g of a white polymer. The molecular weight of the obtained copolymer, 2-hydroxy-2, calculated from 1H-NMR,
The content of 2-dimethylacetic acid units, the average number of chains of 2-hydroxy-2,2-dimethylacetic acid units calculated from 13C-NMR, the moisture permeability coefficient, and the tensile strength were measured. Table 1 shows the results
Shown in Biodegradability was confirmed in this polymer.

[0043]

Embodiment 9 50 equipped with a jacket, a distilling pipe and an introducing pipe
After sufficiently replacing the 0 ml glass-lined tank reactor with nitrogen, L-2-hydroxy-dehydrated and purified under nitrogen.
100 g of methyl 2-ethyl-2-methylacetate (α-hydroxy-α-methylbutyrate) and 2.70 of ε-caprolactone similarly dehydrated and purified under nitrogen.
g, lithium-t-butoxide 0.0028 g, 250 ml of benzene purified by dehydration distillation under a nitrogen atmosphere, a stir bar, and a jacket temperature of 95 ° C.
Continued for hours. At that time, the reaction was performed while continuously supplying the same amount of dehydrated and purified benzene as the distilled benzene to the system. After the completion of the polymerization reaction, benzene was distilled off, and the polymer was taken out, added to 1,000 g of acetic anhydride, and refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature,
The precipitated polymer was filtered, washed with a large amount of methanol, and then separated by filtration and dried to obtain 98 g of a white polymer. The 13C-NMR of the ester carbon in the copolymer shows chemical shift δ = 166.3 ppm, 167.3 ppm, 1
A peak at 70.8 ppm was confirmed. Of these, δ
= 167.3 ppm and 170.8 ppm are the ester carbon (δ = 166.3 ppm) of the poly-2-hydroxy-2-ethyl-2-methylacetic acid homopolymer and the ester carbon (δ) of the polyε-caprolactone homopolymer. = 17
(3.5 ppm). The molecular weight of the obtained copolymer, the content of 2-hydroxy-2,2-dimethylacetic acid unit calculated from 1H-NMR, 13C
The average number of chains, the moisture permeability coefficient, and the tensile strength of the 2-hydroxy-2,2-dimethylacetic acid unit calculated from -NMR were measured. Table 1 shows the results. Biodegradability was confirmed in this polymer.

[0044]

Example 10 5 equipped with a jacket, a distilling pipe, and an introducing pipe
After sufficiently replacing the 00 ml glass-lined tank reactor with nitrogen, 100 g of methyl α-hydroxyisobutyrate dehydrated and purified under nitrogen, and 19.3 g of ε-caprolactone similarly dehydrated and purified under nitrogen, lithium-t 0.0028 g of butoxide, 250 ml of benzene purified by dehydration distillation under a nitrogen atmosphere, and a stirrer bar were charged, and the reaction was continued for 100 hours while azeotroping benzene and methanol as a by-product at a jacket temperature of 95 ° C. After 100 hours, glycerin 0.04 sufficiently dehydrated under nitrogen
g was added and the reaction was continued for another 100 hours. In a series of these reaction processes, the reaction was carried out while continuously supplying the same amount of dehydrated and purified benzene as the distilled benzene to the system. After the completion of the polymerization reaction, benzene was distilled off, and the polymer was taken out, added to 1,000 g of acetic anhydride, and refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature,
The precipitated polymer was filtered, washed with a large amount of methanol, and separated by filtration to obtain 115 g of a white polymer. The molecular weight of the obtained copolymer, 2-, calculated from 1H-NMR
Hydroxy-2,2-dimethylacetic acid unit content, 13
The average number of chains, moisture permeability coefficient, and tensile strength of the 2-hydroxy-2,2-dimethylacetic acid unit calculated from C-NMR were measured. Table 1 shows the results. Biodegradability was confirmed in this polymer.

[0045]

Embodiment 11 5 equipped with a jacket, a distilling pipe and an introducing pipe
After thoroughly replacing the glass-lined tank reactor of 100 ml with nitrogen, 100 g of methyl α-hydroxyisobutyrate dehydrated and purified under nitrogen, and lithium-t-butoxide 0.0
The reaction was continued for 200 hours while 009 g, 250 ml of dehydrated and distilled purified benzene and a stirrer bar were charged in a nitrogen atmosphere, and azeotroping of benzene and methanol as a by-product was performed at a jacket temperature of 95 ° C. After 200 hours, dimethyl terephthalate, ethylene glycol, and dimethyl adipate, which are sufficiently dried under nitrogen, are used as raw materials, and 20 mol% of terephthalic acid unit component, 50 mol% of ethylene glycol unit component, and 30 mol% of adipic acid unit component are prepared.
Was added to the system, and the reaction was continued for another 100 hours. In a series of these reaction processes, the reaction was carried out while continuously supplying the same amount of dehydrated and purified benzene as the distilled benzene to the system. After the completion of the polymerization reaction, benzene was distilled off, and the polymer was taken out, added to 1,000 g of acetic anhydride, and refluxed for 1 hour under a nitrogen atmosphere. After cooling at room temperature,
The precipitated polymer was filtered, washed with a large amount of methanol, and then separated by filtration and dried to obtain 110 g of a white polymer. The molecular weight of the obtained copolymer, 2-, calculated from 1H-NMR
Hydroxy-2,2-dimethylacetic acid unit content, 13
Table 1 shows the results of measuring the average number of chains, the moisture permeability coefficient, and the tensile strength of the 2-hydroxy-2,2-dimethylacetic acid unit calculated from C-NMR. Biodegradability was confirmed in this polymer.

[0046]

Example 12 The copolymer obtained in Example 10 was
0.5% by weight of talc was added as a foam adjusting agent, and the mixture was melt-kneaded at 250 ° C. by an extruder, butane was injected, and the cylinder temperature of the extruder after press-fitting was set to 115 ° C. and released from the slit to the atmosphere. A foam sheet was obtained. The apparent specific gravity of the obtained foamed sheet was 0.13 g / cc. Biodegradability was confirmed in this foam sheet.

[0047]

Example 13 The copolymer obtained in Example 1 was heated to 220 ° C.
Was melt-spun with a spinning machine set at a temperature of about 0.3 mm and processed into fibers having a thickness of about 0.3 mm. Biodegradability was confirmed in this transparent fiber.

[0048]

[Table 1]

The abbreviations used in the table are as follows. HIBA: 2-hydroxy-2,2-dimethylacetic acid unit, HEMA: 2-hydroxy-2-ethyl-2-methylacetic acid unit CL: ε-caprolactone unit LA: L-(-)-lactic acid unit TP: Terephthalic acid unit EG: ethylene glycol unit AD: adipic acid unit The average chain number used in the table indicates the average chain number of 2-hydroxy-2,2-dimethylacetic acid unit, and the molecular weight indicates the weight average molecular weight.

[0050]

According to the present invention, the polyester copolymer containing 99.2 to 50 mol% of 2-hydroxy-2,2-dialkylacetic acid units has practical mechanical properties, thermal properties, and biodegradability. Since it has a characteristic of low moisture permeability, it is suitable as a biodegradable resin molded product that can be used in a wide range of fields and as a raw material thereof.

[Brief description of the drawings]

FIG. 1 is a 13C-NMR chart of normal measurement of 2-hydroxyisobutyric acid and ε-caprolactone copolymer obtained in Example 1 using heavy chloroform as a solvent.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C08J 5/00 CFD C08J 5/00 CFD C08L 67:00 F term (Reference) 4F071 AA44 AF01 AF52 AH05 AH19 BC01 BC04 BC07 4F074 AA68 AA68F AA68G AB01 BA37 BA38 BC11 CA22 CB53 CC04W CC05Z DA02 DA24 DA32 DA33 DA34 DA46 4J029 AA05 AB01 AB04 AB07 AC03 AD01 AD06 AD10 AE01 AE02 AE03 AE18 BA02 BA03 CA04 BD03 CB04A CB05A CB06A CD03 EA02 EA03 EA05 EG02 EG05 EG07 EG09 EH01 EH02 EH03 FC02 FC03 FC08 FC12 FC14 FC36 GA13 GA14 HA01 HB01 HB03A HB06 KB02 4L035 BB31 DD14 EE04 EE07 EE08 EE20H01

Claims (9)

[Claims] 1. (A) 99.2 to 50 mol% of a 2-hydroxy-2,2-dialkylacetic acid unit composed of the same or different alkyl groups having 1 to 5 carbon atoms, and (B) (a)
Polyester comprising one or more copolymerized units selected from the group consisting of hydroxycarboxylic acids other than 2-hydroxy-2,2-dialkylacetic acid, (b) polyvalent carboxylic acids and (c) polyhydric alcohols A copolymer having a weight average molecular weight of 10,000 or more and 1,500,0
A biodegradable polyester copolymer having a molecular weight of 00 or less. 2. The biodegradable polyester according to claim 1, wherein the average number of chains of 2-hydroxy-2,2-dialkylacetic acid units comprising the same or different alkyl groups having 1 to 5 carbon atoms is 2 or more and 60 or less. Polymer. 3. The method according to claim 1, wherein the 2-hydroxy-2,2-dialkylacetic acid unit is 2-hydroxy-2,2-dimethylacetic acid (2-
The biodegradable polyester copolymer according to claim 1 or 2, which is (hydroxyisobutyric acid). 4. The biodegradable polyester copolymer according to claim 3, wherein the copolymer unit is a hydroxycarboxylic acid unit. 5. (A) a 2-hydroxy-2,2-dialkylacetic acid monomer, an ester monomer thereof, or a cyclic 2 thereof comprising the same or different alkyl groups having 1 to 5 carbon atoms.
(B) (a) a hydroxycarboxylic acid monomer other than 2-hydroxy-2,2-dialkylacetic acid, its ester monomer and its cyclic dimer, and (b) a polyvalent carboxylic acid monomer And (c) copolymerizing by alternately dividing and adding one or more monomers selected from the group consisting of polyhydric alcohol monomers or two or more monomers or cyclic dimers. Item 3. A method for producing the biodegradable polyester copolymer according to Item 2. 6. A molded article comprising the biodegradable polyester copolymer according to claim 1, 2, 3 or 4. 7. A sheet comprising the biodegradable polyester copolymer according to claim 1, 2, 3 or 4. 8. A foam comprising the biodegradable polyester copolymer according to claim 1, 2, 3 or 4. 9. A fiber comprising the biodegradable polyester copolymer according to claim 1, 2, 3 or 4.