JPH10279786A - Biodegradable, lactic acid-based copolymer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable, lactic acid-based copolymer composition, suitable for films or the like, excellent in transparency, flexibility and resistance to shock. SOLUTION: This composition comprises (A) a lactic acid-based copolymer obtained by copolymerizing 50 to 99 wt.% of lactide and 1 to 50 wt.% of a polyester, and (B) at least one type of the compounds shown by formula I through IV, (I): R1 OOC-L1 -COOR2 , (II): R2 OOC-L2 -COOR4 , (III):R5 OOC-L3 -COOR6 and (IV): R7 OOC-L4 -COOR8 (L1 to L4 are each a 1-10C alkylene or 6-10C arylene, wherein each of L2 and L4 has an ester functional group as a substituent; and R1 to R8 are each an alkyl or aryl, wherein R1 and/or R2 , and R5 and/or R6 have an ester functional group as a substituent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a biodegradable lactic acid-based copolymer composition. More specifically, transparency, flexibility, excellent impact resistance, packaging materials, medical materials, industrial materials, industrial supplies, containers and the like is particularly required flexibility, for example, film, tape, sheet The present invention relates to a biodegradable lactic acid-based copolymer composition suitable as a material for lactic acid.

[0002]

2. Description of the Related Art In recent years, polyethylene, polypropylene,
A huge amount of plastic products such as polystyrene, polyethylene terephthalate, and vinyl chloride are used,
These waste treatments have been highlighted as one of the environmental problems. That is, the current waste treatment is incineration or burial treatment. For example, incineration of polyethylene or the like results in high burned calories, which damages the incinerator and shortens its life. Further, when polyvinyl chloride or the like is incinerated, harmful gases are generated. On the other hand, land is limited for burying plastic products. Further, when disposed in a natural environment, the chemical stability thereof is extremely high, and there is almost no biological decomposition by microorganisms and the substance remains almost semi-permanently. For this reason, the landscape is damaged, and in addition, there is a problem that the living environment of marine life is polluted.

In order to solve these problems, research and development of biodegradable polymers for conventional plastics have been advanced. One of the biodegradable polymers is polylactic acid. Polylactic acid undergoes hydrolysis and microbial degradation in the natural environment, eventually breaking down to carbon dioxide and water. In addition, even if incineration is performed, there is no damage to the incinerator and no generation of harmful gas because the calorie burned is small. In this way, the problem of waste disposal is greatly reduced. In addition, polylactic acid uses lactic acid obtained from renewable plant resources as a raw material, and is therefore more promising in terms of resources than conventional plastics synthesized from petroleum raw materials. Further, polylactic acid is characterized by having higher transparency than other biodegradable polymers.

However, since polylactic acid has low flexibility and rigidity, it has been considered that polylactic acid is not suitable as a material for films, tapes, sheets and the like in which polyethylene and the like are mainly used. Lactic acid copolymers are generally softer than lactic acid homopolymers, but are also less flexible and harder.

[0005] In order to impart flexibility to polylactic acid, polylactic acid is added with a plasticizer such as ethyl benzoate or diester compounds such as dioctyl phthalate, diisobutyl adipate and dioctyl sebacate. (For example, JP-A-4-335060). However, these have insufficient plasticizing effects, and bleed-out is likely to occur even if they have a plasticizing effect. Also,
Japanese Patent Application Laid-Open No. Hei 7-118513 discloses that a polylactic acid or a lactic acid copolymer has a number average molecular weight of 5 to impart flexibility.
A polylactic acid composition to which 00 to 2000 polyester-based plasticizers are added is disclosed. However, the polyester plasticizer disclosed in the above-mentioned publication goes through a complicated process of further blocking the terminal of the polyester obtained by the reaction between the dibasic acid and the dihydric alcohol with a monobasic acid and / or a monohydric alcohol. Since it is manufactured, it is not preferable from a practical viewpoint.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide transparency, flexibility, and the like.
An object of the present invention is to provide a biodegradable lactic acid-based copolymer composition suitable as a material of a molded article having excellent impact resistance, particularly, a material of a film, a tape, and a sheet.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that by using a compound having a specific structure having at least three ester bonds in a molecule as a plasticizer,
It has been found that the above object can be achieved, and the present invention has been completed.

That is, the biodegradable lactic acid-based copolymer composition of the present invention comprises a lactic acid copolymer obtained by copolymerizing 50 to 99% by weight of lactide and 1 to 50% by weight of a polyester with the following general formula (I): It is characterized by containing at least one compound represented by the general formula (II), (III) or (IV) and having at least three ester bonds in a molecule.

Formula (I) R ₁ OOC-L ₁ -COOR _{2 In the} formula (I), L ₁ is a single bond, having 1 to 10 carbon atoms.
Is an alkylene group or an arylene group having 6 to 10 carbon atoms, and R _{1 to} R ₂ may be the same or different, and are an alkyl group or an aryl group, and at least one of R _{1 to} R ₂ is a substituent. Has an acyloxy group, an alkoxycarbonyl group or an aryloxycarbonyl group.

General formula (II) R ₃ OOC-L ₂ —COOR _{4 In} general formula (II), L ₂ is an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, Has at least one of an acyloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, and an alkyl group substituted with any of these groups. R _{3 to} R ₄ may be the same or different and are an alkyl group or an aryl group.

[0011] In the general formula _{(III) R 5 COO-L} 3 -OCOR 6 formula (III), L ₃ represents an alkylene group or an arylene group having 6 to 10 carbon atoms having 1 to 10 carbon atoms,
R _{5 to} R ₆ may be the same or different and are an alkyl group or an aryl group, and at least one of R _{5 to} R ₆ has an acyloxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group as a substituent.

Formula (IV) R ₇ COO-L ₄ —OCOR _{8 In the} general formula (IV), L ₄ is an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, Has at least one of an acyloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, and an alkyl group substituted with any of these groups. R _{7 to} R ₈ may be the same or different and are an alkyl group or an aryl group.

[0013] The composition of the present invention is generally used in the formula (I) or the formula (I) based on 100 parts by weight of a lactic acid copolymer.
It contains 5 to 50 parts by weight of at least one of the compounds represented by formula (I), formula (III) or formula (IV).

Hereinafter, the present invention will be described in detail. In the present invention, the lactic acid copolymer is obtained by copolymerizing 50 to 99% by weight of lactide, which is a cyclic dimer of lactic acid, and 1 to 50% by weight of an aliphatic or aromatic or aliphatic aromatic polyester. is there. The weight average molecular weight of the lactic acid copolymer is generally 50,000 to 500,000.

Lactide includes L-lactide, D-lactide and meso-lactide. The synthesis, purification and polymerization of lactide are described in, for example, US Pat. No. 4,057,537 and published European Patent Application No. 261572. , Poly
mer Bulletin, 14, 491-495 (1985), and Makromol Che
m., 187, 1611-1628 (1986).

The type of the polyester is not particularly limited, and may be any of an aliphatic polyester, an aromatic polyester and an aliphatic aromatic polyester, and the obtained copolymer has good biodegradability. Anything is fine. Examples of such polyesters include, for example, aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, and sebacic acid, and ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,8-octane. Aliphatic polyesters containing aliphatic diols such as diols as constituents; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid, and ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1 Aromatic polyesters comprising aliphatic diols such as 1,8-octanediol and the like; and aliphatic aromatic polyesters comprising the above-mentioned aliphatic dicarboxylic acids, aromatic dicarboxylic acids and aliphatic diols.

Further, the polyester may be composed of hydroxycarboxylic acid, lactone and the like. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutylcarboxylic acid, and those described in JP-A-6-184417. Lactones include glycolide, ε-caprolactone glycolide, ε
-Caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, δ-valerolactone and the like. Further, the polyester may have a urethane bond in the polymer chain.

Such a polyester can be easily obtained by a dehydration condensation reaction between the above components. Also,
By adding a diisocyanate component such as hexamethylene diisocyanate to the reaction system, a urethane bond can be incorporated in the polymer chain.

The lactic acid copolymer of the present invention can be produced by copolymerizing 50 to 99% by weight of lactide and 1 to 50% by weight of polyester by ring-opening polymerization of lactide by a known method. For example, JP-A-7-
As described in JP-A-173266, the lactide and the polyester polymer can be prepared by mixing and heating after an inert gas atmosphere in the presence of a ring-opening polymerization catalyst.

The catalyst used in the polymerization reaction is not particularly limited, but a known lactic acid polymerization catalyst can be used. For example, organic tin compounds such as tin lactate, tin tartrate, tin dicaprylate, tin dilaurate, tin dipalmitate, tin distearate, tin dioleate, tin α-naphthoate, β-tin naphthoate, and tin octylate Zinc powder, zinc halide, zinc oxide, organic zinc compounds; titanium compounds such as tetrapropyl titanate; zirconium compounds such as zirconium isopropoxide; antimony compounds such as antimony trioxide; Bismuth compounds such as bismuth (III) oxide; aluminum compounds such as aluminum oxide and aluminum isopropoxide; Among these, a catalyst composed of tin or a tin compound is particularly preferred from the viewpoint of activity. The use amount of these catalysts is generally about 0.001 to 5% by weight based on lactide.

If the amount of lactide used in this copolymerization reaction is less than 50% by weight and the amount of polyester exceeds 50% by weight, the molecular weight of the obtained copolymer is lowered and the melting point is lowered, so that the performance required for practical use cannot be obtained. On the other hand, when the content of lactide exceeds 99% by weight and the content of polyester is less than 1% by weight, the obtained copolymer is hard, brittle and poor in flexibility. The lactic acid copolymer in the present invention is preferably 70 to 90% by weight of lactide and 10 to 3% of polyester.
0% by weight is obtained by copolymerization.

In the present invention, the lactide content in the lactic acid copolymer is desirably 1% by weight or less. When the lactide content exceeds 1% by weight, the properties of the obtained thermoplastic resin are affected, which is not desirable.

The composition of the present invention contains at least one of the compounds represented by the general formulas (I), (II), (III) and (IV). First, the general formula (I) will be described in detail. R ₁ OOC-L ₁ -COOR _{2 In the} general formula (I), L ₁ is a single bond, having 1 to 10 carbon atoms.
Or an arylene group having 6 to 10 carbon atoms. More specifically, the —OC-L ₁ —CO— unit is composed of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, Terephthalic acid, 1,2-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 1,
It is derived from any of 4-naphthalenedicarboxylic acids. Among these, those derived from any of adipic acid, sebacic acid, phthalic acid, isophthalic acid and terephthalic acid are preferred.

R _{1 and} R ₂ may be the same or different and each represents an alkyl group or an aryl group, and at least one of R _{1 and} R ₂ is an acyloxy group, an alkoxycarbonyl group or an aryloxycarbonyl group as a substituent. Having.

The alkyl group as R _{1 to} R ₂ includes:
For example, an alkyl group having up to 10 carbon atoms or an alkyl group in which a substituent is introduced into the above-mentioned alkyl group can be mentioned. Specific examples of such an alkyl group include methyl, ethyl,
n-propyl, isopropyl, n-butyl, isobutyl, se
c-butyl, pentyl, hexyl, heptyl, octyl,
2-ethylhexyl, nonyl, decyl, methoxymethyl, methylthiomethyl, 2- (trimethylsilyl) ethoxymethyl, benzyloxymethyl, phenacyl, p-
Bromophenacyl, N-phthalimidomethyl, 2,2,2-trichloroethyl, allyl, benzyl, substituted benzyl and the like. Of these, phenacyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, benzyl, and substituted benzyl groups are useful in raw material availability, ease of introduction, effect as a plasticizer, safety, etc. Preferred from the point.

The aryl group as R _{1 to} R ₂ includes
For example, phenyl, p-methoxyphenyl, p-methylphenyl, p-ethylphenyl, p-ethoxyphenyl, p-chlorophenyl group and the like can be mentioned.

At least one of R _{1 and} R ₂ has, as a substituent, an acyloxy group (—OCOR ₁₁ ), an alkoxycarbonyl group (—COOR ₁₂ ) or an aryloxycarbonyl group (—COOR ₁₃ ). Here, R ₁₁ is an alkyl group or an aryl group, R ₁₂ is an alkyl group, and R ₁₃ is an aryl group. As the alkyl group for R ₁₁ and R ₁₂ , a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, pentyl, hexyl , Heptyl, octyl, 2-ethylhexyl, methoxymethyl, allyl and the like. R ₁₁ , R
_{As the 13} aryl group, a substituted or unsubstituted phenyl group having 1 to 8 carbon atoms, for example, phenyl, p-methoxyphenyl, p-methylphenyl, p-ethylphenyl, p-
An ethoxyphenyl, p-chlorophenyl group and the like can be mentioned.

As a substituent, an acyloxy group (—OCOR)
₁₁ ), R _{1 to} R ₂ having an alkoxycarbonyl group (—COOR ₁₂ ) or an aryloxycarbonyl group (—COOR ₁₃ ) are preferably methoxycarbonylmethyl, 1-methyl-2- (ethoxycarbonyl) ethyl, 4- (ethoxycarbonyl) butyl, phenoxycarbonylmethyl, 2- (acetyloxy) ethyl, benzoyloxymethyl, 3- (benzoyloxy) propyl group and the like.

As a special case in the general formula (I), R
_A compound in which ₁ and / or R ₂ is —CH (CH ₃ ) COOR ₉ (where R ₉ is an alkyl group or an aryl group). That is, -OCH
(CH ₃ ) COOR ₉ is a unit derived from lactic acid, has very good compatibility with the lactic acid copolymer of the previous period, and has very good plasticizing efficiency. Examples of the alkyl group for R ₉ include a methyl, ethyl, propyl, butyl, pentyl, hexyl, benzyl, and 2-methoxyethyl group,
Examples of the aryl group include a phenyl group.

Preferred compounds of the general formula (I) include L
₁ : — (CH ₂ ) ₄ —, R ₁ and R ₂ : —CH ₂ COO
A compound of CH ₂ CH ₃ ; L ₁ : — (CH ₂ ) ₄ —, R
₁ : a compound of isobutyl, R ₂ : —CH ₂ COOCH ₃ ; L ₁ : — (CH ₂ ) ₈ —, R ₁ and R ₂ : —CH
A compound of ₂ COOCH ₃ ; L ₁ : — (CH ₂ ) ₈ —,
R ₁ and R ₂ : a compound of —CH (CH ₃ ) COOCH ₃ (compound (1) of Example); L ₁ : 1,2-phenylene, R
₁ and R ₂ : a compound of —CH (CH ₃ ) COOCH ₃ (compound (4) of the example) and the like.

The compound of the general formula (I) is, for example, HOOCL
₁ COOH (or dihalide) and R ₁ OH and R ₂ O
It can be easily synthesized by a method of condensing with H or the like.

Next, the general formula (II) will be described in detail. R ₃ OOC-L ₂ —COOR _{4 In the} general formula (II), L ₂ is an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, and as a substituent, an acyloxy group, an alkoxycarbonyl group, It has at least one of an aryloxycarbonyl group and an alkyl group substituted with any of these groups. More specifically, _-OC-L 2 -CO- units, tartaric acid, citric acid, isocitric acid, malic acid, 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid,
It is derived from any of 1,3,5-benzenetricarboxylic acids. That is, for example, malic acid (HOOCC)
H (OH) CH ₂ COOH), L ₂ may be, for example,-
CH (OCOCH ₃ ) CH ₂ —. Also, for example, 1,
When it is derived from 3,5-benzenetricarboxylic acid, L ₂ is, for example, 1-ethoxycarbonyl-2,3-phenylene in which the carboxylic acid at the 1-position is ethylesterified.

R _{3 to} R ₄ may be the same or different and are an alkyl group or an aryl group. Specific examples of R _{3 and} R ₄ include the same as those of R _{1 and} R ₂ described above. It is not essential that R ₃ and / or R ₄ have an acyloxy group, an alkoxycarbonyl group or an aryloxycarbonyl group as a substituent, but they may have these substituents.

As a special case in the general formula (II), R
_A compound in which ₃ and / or R ₄ is —CH (CH ₃ ) COOR ₁₀ (where R ₁₀ is an alkyl group or an aryl group). An alkyl group for R ₁₀ ,
As the aryl group, the same as those in the case of R ₉ can be mentioned.

Preferred compounds of the general formula (II) include L
_{2: -CH (OCOCH 3) CH} 2 -, R 3: isobutyl, R _4: Compound of _{-CH 2 COOCH 3; L 2:} 1-
Ethoxycarbonyl-3,5-phenylene, R ₃ and R ₄ :
Compound of 1-methyl-2- (ethoxycarbonyl) ethyl; L ₂ : —CH ₂ C (OCOCH ₃ ) (CH ₂ CO
_{OC 4 H 9 -n) -,} R 3 and R _4: - (the compound of Example (5) n-butyl) and the like.

The compound of the general formula (II) is, for example, HOOCL
₂ COOH (or dihalide) with R ₃ OH and R ₄ O
It can be easily synthesized by a method of condensing with H or the like.

Next, the general formula (III) will be described in detail. R ₅ COO-L ₃ -OCOR _{6 In the} general formula (III), L ₃ is an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms. More specifically, the —OL ₃ —O— unit is ethylene glycol, 1,3-propanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, catechol, resorcinol, or hydroquinone Is derived from Among these, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, those derived from any of catechol are preferred .

R _{5 to} R ₆ may be the same or different and are an alkyl group or an aryl group, and at least one of R _{5 to} R ₆ is an acyloxy group, an alkoxycarbonyl group or an aryloxycarbonyl group as a substituent. Having. Specific examples of R _{5 to} R ₆ include the aforementioned R _{1 to} R ₂
And an acyloxy group (—OCOR ₁₁ ), an alkoxycarbonyl group (—COOR ₁₂ ) or an aryloxycarbonyl group (—
The same can be mentioned for COOR ₁₃ ).

Preferred compounds of the general formula (III) include:
_{L 3 :-( CH 2) 4 -} , R 1 and R ₂ :-( CH _2)
4 COOCH ₂ CH ₃ compound; L ₃ : 1,2-phenylene, R ₁ and R ₂ :-(CH ₂ ) ₄ COOCH ₃ compound and the like.

The compound of the general formula (III) is, for example, HOL ₃
It can be easily synthesized by a method of condensing OH with R ₅ COOH and R ₆ COOH or the like.

Next, the general formula (IV) will be described in detail. R ₇ COO-L ₄ -OCOR _{8 In the} general formula (IV), L ₄ is an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, and an acyloxy group, an alkoxycarbonyl group, It has at least one of an aryloxycarbonyl group and an alkyl group substituted with any of these groups. More specifically, the —OL ₄ —O— unit is derived from any of glyceric acid, glycerin, pentaerythritol, and pyrgallol. That is,
For example, if it is derived from glycerin,
L ₄ is, for example, —CH ₂ CH (OCOC ₃ H ₇ -n) CH
_2- . Further, for example, when it is derived from pentaerythritol, L ₄ is, for example, —CH _{2
C (CH 2 OCOPh) 2 CH} 2 - it is.

R _{7 to} R ₈ may be the same or different and are an alkyl group or an aryl group. Specific examples of R _{7 and} R ₈ include the same as those of R _{1 and} R ₂ described above. It is not essential that R ₇ and / or R ₈ have an acyloxy group, an alkoxycarbonyl group or an aryloxycarbonyl group as a substituent, but they may have these substituents.

Preferred compounds of the general formula (IV) include L
₄ : —CH ₂ CH (OCOC ₃ H ₇ -n) CH ₂ —, R ₇
And R ₈ : a compound of —C ₃ H ₇ —n (compound (2) of Example)
_{); L 4: -CH 2 C} (CH 2 OCOPh) 2 CH 2
-, R ₇ and R _8: the compound of -Ph (the compound of Example
(3)) and the like.

The compounds of the general formula (IV) are, for example, glycerin, pentaerythritol or pyrgallol with R ₇ CO
It can be easily synthesized by a method of condensing OH and R ₈ COOH (or a halide).

In the composition of the present invention, the compound represented by the general formula (I)
, One of the compounds represented by the general formula (II), the general formula (III) or the general formula (IV) may be used alone, or two or more may be used. The amount of these plasticizers varies depending on the composition of the lactic acid copolymer (DL ratio of lactide used, ratio of the polyester copolymer component), the purpose of use of the composition, and the like. The total amount of the compounds represented by the general formulas (I), (II), (III) and (IV) is about 5 to 60 parts by weight. If the amount is less than 5 parts by weight, sufficient flexibility cannot be imparted to the lactic acid copolymer composition. On the other hand, if the amount exceeds 60 parts by weight, bleeding may occur depending on the type of the plasticizer to be added. A more preferable amount is about 5 to 30 parts by weight, and a still more preferable amount is about 10 to 30 parts by weight.

As described above, since the composition of the present invention is based on the combination of a specific lactic acid copolymer which is softer than a lactic acid homopolymer and a plasticizer having a specific structure, a relatively small amount of the plasticizer is required. Therefore, there is no adverse effect such as a decrease in elastic modulus and an increase in elongation at break caused by adding a large amount of a plasticizer. When the lactic acid copolymer is a lactide-polyester random copolymer, the copolymer itself becomes flexible and the amount of the plasticizer can be reduced.

In the composition of the present invention, if necessary, antioxidants, heat stabilizers, light stabilizers, coloring agents, antistatic agents, lubricants, flame retardants, foaming agents, fillers, antibacterial and antifungal agents Various additives such as an agent can also be blended.

The method of blending the plasticizer and the above-mentioned various additives is not particularly limited, and can be carried out by a conventionally known method. For example, mixing and kneading may be performed using a mill roll, a Banbury mixer, a super mixer, a single screw or twin screw extruder, or the like.

The composition of the present invention can be molded by a molding method such as extrusion molding, injection molding, vacuum molding, compression molding, etc., similarly to general plastics. Films, tapes, sheets, plates, Various molded articles such as rods, bottles and containers can be obtained. The molding temperature is usually 1
It is about 00 to 300 ° C.

Although the mechanical strength of the molded article varies depending on the purpose of use of the molded article, it is generally 3 to 0.001.
GPa, tensile strength 70 to 5 MPa, elongation at break 10 to 30
0% is preferred. The addition of the plasticizer causes a decrease in the elastic modulus and an increase in the elongation at break. However, the molded article is likely to be damaged due to the decrease in the strength, which requires a certain level of strength. In particular, in the case of a film, tape, or sheet, the tensile elastic modulus is preferably 0.5 to 0.001 GPa, the tensile strength is 40 to 10 MPa, and the elongation at break is preferably 200 to 500%.

The lactic acid-based copolymer composition of the present invention contains a specific lactic acid copolymer which is more flexible than a lactic acid homopolymer and a plasticizer compound having a specific structure, so that a relatively small amount of the plasticizer can provide sufficient flexibility. Can be Since the blending amount of the plasticizer is relatively small, the transparency of the copolymer is not impaired. Therefore, the molded product obtained from the copolymer composition has problems such as a decrease in the transparency of the molded product and bleeding. There is no, and it is flexible and strong.

The lactic acid copolymer composition of the present invention can be used for packaging materials, medical materials, industrial materials, industrial supplies,
Although a container etc. are mentioned, it is suitable especially as a material of a film, a tape, and a sheet which require flexibility.

[0053]

The present invention will be described more specifically with reference to examples and comparative examples. [Synthesis Example of Compound (1)] Sebacic acid dichloride and 2 equivalents of methyl lactate were reacted in dichloromethane with pyridine as a deoxidizing agent. Purification by a conventional method gave Compound (1).

[Synthesis Example of Compound (3)] Pentaerythritol was reacted with 4 equivalents of benzoic acid chloride in dichloromethane using pyridine as a deoxidizing agent. Purification by a conventional method gave Compound (3).

[Synthesis Example of Compound (4)] Phthalic acid dichloride was reacted with 2 equivalents of methyl lactate in dichloromethane using pyridine as a deoxidizing agent. Purification by a conventional method gave Compound (4). The compound (2) used tributyrin (manufactured by Nacalai Tesque), and the compound (5) used tributyl acetylcitrate (manufactured by Nacalai Tesque).

[0056]

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[0057]

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[0058]

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[0059]

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[0060]

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[Synthesis Example of Lactic Acid Copolymer PLC-1] Succinic acid unit and 1,4-butanediol unit (molar ratio 1:
30 parts by weight of aliphatic polyester PE-1 (weight average molecular weight: 100,000) having 1) as a constitutional unit and 70 parts by weight of L-lactide are melt-mixed in an inert gas atmosphere, and a ring-opening polymerization catalyst is prepared. Was added at 0.20% by weight (relative to lactide), and the mixture was polymerized at 190 ° C. for 15 minutes while stirring with a twin-screw kneader. Further, the mixture was treated in nitrogen at 120 ° C. and a pressure of 1.5 kg / cm ² for 12 hours to remove unreacted monomers to obtain a lactic acid copolymer PLC-1 (weight average molecular weight: 135,000).

[Synthesis example of lactic acid copolymer PLC-2] Aliphatic polyester PE-2 having succinic acid unit, adipic acid unit and 1,4-butanediol unit (molar ratio, 40:10:50) as constituent units (Weight average molecular weight: 95,0
00) 30 parts by weight and 70 parts by weight of L-lactide were melt-mixed in an inert gas atmosphere, and tin octylate was added as a ring-opening polymerization catalyst in an amount of 0.24% by weight (based on lactide). Polymerization was performed at 190 ° C. for 15 minutes while stirring with a shaft kneader. Further, the mixture was treated for 12 hours in nitrogen at a pressure of 1.5 kg / cm ² at 120 ° C. to remove unreacted monomers, and the lactic acid copolymer PLC-2 (weight average molecular weight: 140,0
00).

[Synthesis Example of Lactic Acid Copolymer PLC-3] Aliphatic polyester having terephthalic acid unit, adipic acid unit and 1,4-butanediol unit (molar ratio: 1: 1.25: 2.25) as constituent units PE-3 (weight average molecular weight:
95,000) 30 parts by weight of L-lactide and 70 parts by weight of L-lactide were melt-mixed under an inert gas atmosphere, and 0.24% by weight of tin octylate (based on lactide) was added as a ring-opening polymerization catalyst. 15 at 190 ° C while stirring with a twin-screw kneader
Polymerized for minutes. Further, at 120 ° C. and a pressure of 1.5 kg / c
m ² of nitrogen for 12 hours to remove unreacted monomers and to give a lactic acid copolymer PLC-3 (weight average molecular weight: 1
10,000).

<Weight average molecular weight of polymer> The polymer was measured by GPC under the following conditions and determined in terms of polystyrene. Detector: RID-6A, Pump: LC-9A, Column oven: GT
O-6A, Column: Shim-pack GPC-801C, -804C, -806C, -8
025C in series (manufactured by Shimadzu Corporation) Solvent: chloroform, flow rate: 1 ml / min, sample amount: 200 μl (0.5 w / w% of sample was dissolved in chloroform), column temperature: 40 ° C.

Example 1 150 g of PLC-1 and 30 g of compound (1) were charged into a twin-screw kneader controlled at 190 ° C., melt-kneaded for 20 minutes, and formed into chips. From the copolymer composition chip, a JIS K 7113 No. 2 test piece (thickness: 3 mm) was prepared at 190 ° C. by using an injection molding machine, and a tensile test was performed. The tensile strength (MPa), the tensile modulus (MPa), The elongation at break (%) was measured. Further, when the molecular weight of the lactic acid copolymer was measured by GPC with respect to the chip and the No. 2 test piece, there was no change in the molecular weights of both, and it was confirmed that the decomposition of the lactic acid copolymer did not occur due to heat during injection molding. The obtained No. 2 test piece was transparent.

Example 2 A chip was obtained in the same manner as in Example 1 except that 150 g of PLC-2 and 30 g of Compound (2) were used, and a No. 2 test piece was prepared, and a tensile test was performed.
Also, there was no change in the molecular weight of the chip and the No. 2 test piece,
The obtained No. 2 test piece was transparent.

Example 3 150 g of PLC-3 and 30 g of compound (3) were charged into a twin-screw kneader controlled at 180 ° C., melt-kneaded for 20 minutes, and then formed into chips. From the copolymer composition chip, a No. 2 test piece was prepared in the same manner as in Example 1, and a tensile test was performed. In addition, there was no change in the molecular weight of the chip and the No. 2 test piece, and the obtained No. 2 test piece was transparent.

Example 4 A chip was obtained in the same manner as in Example 3 except that 150 g of PLC-3 and 30 g of compound (4) were used, and a No. 2 test piece was prepared, and a tensile test was performed.
Also, there was no change in the molecular weight of the chip and the No. 2 test piece,
The obtained No. 2 test piece was transparent.

Example 5 A chip was obtained in the same manner as in Example 3 except that 150 g of PLC-3 and 30 g of Compound (5) were used, a No. 2 test piece was prepared, and a tensile test was performed.
Also, there was no change in the molecular weight of the chip and the No. 2 test piece,
The obtained No. 2 test piece was transparent.

Example 6 A chip was prepared in the same manner as in Example 3 except that 150 g of PLC-3 and 10 g of Compound (1) were used, and a No. 2 test piece was prepared, and a tensile test was performed.
Also, there was no change in the molecular weight of the chip and the No. 2 test piece,
The obtained No. 2 test piece was transparent.

Comparative Example 1 A chip was obtained and a No. 2 test piece was prepared in the same manner as in Example 1 except that no compound (1) was added, and a tensile test was performed. In addition, the chip and 2
There was no change in the molecular weight of the No. test piece.

Comparative Example 2 Poly-L-lactic acid obtained by ring-opening polymerization of L-lactide (weight average molecular weight:
180000), a chip was obtained in the same manner as in Example 1, a No. 2 test piece was prepared, and a tensile test was performed. In addition, there was no change in the molecular weight of the chip and the No. 2 test piece.

Comparative Example 3 A chip was obtained in the same manner as in Example 1 except that 150 g of the same poly-L-lactic acid and 30 g of compound (1) were used as in Comparative Example 2, and a No. 2 test was performed. Pieces were prepared and subjected to a tensile test. In addition, there was no change in the molecular weight of the chip and the No. 2 test piece, and the obtained No. 2 test piece was transparent.

Comparative Example 4 A chip was obtained in the same manner as in Example 1 except that 150 g of poly-L-lactic acid and 30 g of compound (2) were used, which were the same as those used in Comparative Example 2. Pieces were prepared and subjected to a tensile test. In addition, there was no change in the molecular weight of the chip and the No. 2 test piece, and the obtained No. 2 test piece was transparent.

Comparative Example 5 A chip was obtained in the same manner as in Example 1 except that 150 g of the same poly-L-lactic acid and 30 g of compound (3) as used in Comparative Example 2 were used, and a No. 2 test was carried out. Pieces were prepared and subjected to a tensile test. In addition, there was no change in the molecular weight of the chip and the No. 2 test piece, and the obtained No. 2 test piece was transparent.

Comparative Example 6 A chip was obtained in the same manner as in Example 1, except that 150 g of poly-L-lactic acid and 30 g of compound (4) were used, which were the same as those used in Comparative Example 2. Pieces were prepared and subjected to a tensile test. In addition, there was no change in the molecular weight of the chip and the No. 2 test piece, and the obtained No. 2 test piece was transparent.

Comparative Example 7 A chip was obtained in the same manner as in Example 1 except that 150 g of poly-L-lactic acid and 30 g of compound (5) were used, which were the same as those used in Comparative Example 2. Pieces were prepared and subjected to a tensile test. In addition, there was no change in the molecular weight of the chip and the No. 2 test piece, and the obtained No. 2 test piece was transparent.

The No. 2 test pieces of Examples 1 to 6 and Comparative Examples 3 to 7 were subjected to two months at room temperature and 40 ° C.
The transparency test was carried out under two conditions of two weeks in a thermostat of the above. Regarding any of the No. 2 test pieces, the transparency was well maintained under these conditions. Table 1 shows the above results.

[0079]

[Table 1]

As shown in Table 1, the test pieces prepared from the polymer compositions of Examples 1 to 6 all had good tensile strength and were compared with those of Comparative Examples 1 and 2 in which no plasticizer was added. The tensile modulus is small and the breaking elongation is large enough.
It is clear that when formed into a film, sheet or the like, it has sufficient impact resistance and flexibility.

In Examples 1 to 5, since lactic acid copolymers obtained by copolymerizing lactide and polyester were used, Comparative Examples 3 to 7 using lactic acid homopolymers were used.
In comparison with the case where the same plasticizer is added, the elongation at break is sufficiently improved. Therefore, it is particularly suitable as a material for films, tapes and sheets requiring flexibility. Furthermore, even when the added amount of the plasticizer is small, as in Example 6, it has excellent performance. Therefore, there is no problem such as a decrease in transparency and bleeding of the molded article due to the addition of the plasticizer.

[0082]

As described above, the lactic acid-based polymer composition of the present invention contains a specific lactic acid copolymer which is more flexible than a lactic acid homopolymer and a plasticizer compound having a specific structure, so that transparency, flexibility and impact resistance are improved. It is useful as a material for molded articles having excellent properties. In particular, since a relatively small amount of the plasticizer is provided with sufficient flexibility, there is no problem such as a decrease in the transparency of the molded product due to the plasticizer, bleeding, etc., and it is extremely useful as a material for films, tapes, sheets, and the like. Are suitable. Further, since the lactic acid-based polymer has biodegradability, the problem of waste disposal such as conventional plastics is reduced.

Claims (8)

[Claims] A lactic acid-based copolymer obtained by copolymerizing 50 to 99% by weight of lactide and 1 to 50% by weight of a polyester, and the following general formula (I), general formula (II), general formula (III) or A biodegradable lactic acid-based copolymer composition comprising at least one compound represented by the general formula (IV) and having at least three ester bonds in a molecule. General formula (I) R ₁ OOC-L ₁ -COOR ₂ (In general formula (I), L ₁ is a single bond, having 1 to 1 carbon atoms.
0 is an alkylene group or an arylene group having 6 to 10 carbon atoms, and R _{1 to} R ₂ may be the same or different and are an alkyl group or an aryl group, and at least one of R _{1 to} R ₂ is substituted. It has an acyloxy group, an alkoxycarbonyl group or an aryloxycarbonyl group as a group. ) In the general formula _{(II) R 3 OOC-L} 2 -COOR 4 ( formula (II), L ₂ is an alkylene group or an arylene group having 6 to 10 carbon atoms having 1 to 10 carbon atoms as a substituent Acyloxy group, alkoxycarbonyl group,
It has at least one of an aryloxycarbonyl group and an alkyl group substituted with any of these groups. R _{3 to} R ₄ may be the same or different and are an alkyl group or an aryl group. ) In the general formula _{(III) R 5 COO-L} 3 -OCOR 6 ( formula (III), L ₃ represents an alkylene group or an arylene group having 6 to 10 carbon atoms having 1 to 10 carbon atoms, R ₅ ~ R ₆ may be the same or different and is an alkyl group or an aryl group, and at least one of R _{5 to} R ₆ has an acyloxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group as a substituent.) General formula (IV) R ₇ COO-L ₄ —OCOR ₈ (In the general formula (IV), L ₄ is an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, and an acyloxy group as a substituent; An alkoxycarbonyl group,
It has at least one of an aryloxycarbonyl group and an alkyl group substituted with any of these groups. R _{7 to} R ₈ may be the same or different and are an alkyl group or an aryl group. ) 2. -OC-L ₁ -in the general formula (I)
CO units are oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,2-naphthalenedicarboxylic acid, 2 The lactic acid copolymer composition according to claim 1, which is derived from any of 1,3-naphthalenedicarboxylic acid and 1,4-naphthalenedicarboxylic acid. 3. The compound represented by the formula (II), wherein —OC—L ₂ —
The CO unit is derived from tartaric acid, citric acid, isocitric acid, malic acid, 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, or 1,3,5-benzenetricarboxylic acid The lactic acid-based copolymer composition according to claim 1 or 2, wherein the composition is prepared. 4. The compound represented by the formula (III), wherein -OL _3-
O-unit is ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-
2. The composition according to claim 1, which is derived from hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, catechol, resorcin, or hydroquinone. The lactic acid-based copolymer composition according to any one of Items 3 to 3. 5. The compound represented by the formula (IV), wherein —OL ₄ —O
The lactic acid-based copolymer composition according to any one of claims 1 to 4, wherein the unit is derived from any of glyceric acid, glycerin, pentaerythritol, and pyrgalol. 6. R ₁ and / or R ₂ in the general formula (I) are —CH (CH ₃ ) COOR ₉ (where R ₉ is an alkyl group or an aryl group), and / Or R ₃ in the general formula (II)
And / or R ₄ is —CH (CH ₃ ) COOR _10, wherein R ₁₀ is an alkyl group or an aryl group. Lactic acid-based copolymer composition. 7. A lactic acid copolymer comprising 50 to 99 lactide.
The lactic acid-based copolymer composition according to any one of claims 1 to 6, wherein the lactic acid-based copolymer composition is obtained by copolymerizing 1% to 50% by weight of a polyester having a urethane bond in a polymer chain. Stuff. 8. A lactic acid copolymer based on 100 parts by weight,
Formula (I), Formula (II), Formula (III) or Formula
At least one compound represented by the formula (IV):
The lactic acid-based copolymer composition according to any one of claims 1 to 7, comprising 0 parts by weight.