KR100525475B1 - Biodegradable pdyeste lopolymer with improved cutting property and antistatic property, and preparation htereof - Google Patents

Abstract

The present invention relates to an antistatic biodegradable polyester copolymer prepared by mixing molten PLA resin in an oligomer prepared by mixing an antistatic component in an ester reaction of an aromatic-aliphatic polyester and then performing a polymerization reaction together. The composition prepared according to the invention is excellent in productivity due to excellent cutting property, and is characterized in that the workability and mechanical strength have properties similar to those of conventional plastics.

Description

Anti-degradable biodegradable polyester copolymer with improved cutting property and manufacturing method thereof Biodegradable pdyeste lopolymer with improved cutting property and antistatic property, and preparation htereof

Plastic is widely used as an indispensable packaging material in modern life because of its cheap properties and low weight.

However, the environmental pollution problem caused by plastic products pouring out all over the world is getting serious day by day. Polyethylene, polypropylene, polyethylene terephthalate (PET), etc. are widely used as general packaging plastics, but these materials may damage the incinerator due to high calorific value during combustion, and such plastic products may be embedded or treated. Due to chemical and biological stability, they hardly decompose and remain, causing problems such as shortening the life of landfills. In order to solve this problem, low heat of combustion, decomposed in the soil, and biodegradable plastics that can achieve the early stabilization of landfill by natural decomposition during landfill has been developed and applied to various applications.

As biodegradable materials and environmentally low-load materials that are currently used, aliphatic polyesters, modified starches, polylactic acid, various composite materials based on these resins, polymer alloys, and the like are known.

Among these, aliphatic polyester resins have high biodegradability and have been widely studied as packaging materials. The fact that aliphatic polyesters are biodegradable has long been known (Journal of Macromol Sci-Chem., A-23 (3), 1986, 393-409). However, these aliphatic polyester resins have low crystallinity and Due to the melting point, the cutting property is lowered due to poor cooling during the cutting after the completion of the polymerization, and the productivity is extremely low due to this, and the tear strength, tensile strength and elongation at the time of film molding with this resin are lower than those of general-purpose polyolefin resins. It is known to be significantly lower.

As an example, aliphatic polyester films containing succinic acid, adipic acid, or both of these and diol components as main structural units are flexible, have high elongation, and have excellent heat seal properties. . However, in the aliphatic polyester, both the glass transition point and the crystallization point are below room temperature, and it is difficult and opaque to suppress the growth of the crystal even if it is quenched immediately after melt extrusion. In addition, when the film is too flexible and the printing of this film or laminating other films, papers, metal thin films, etc., the film is pulled and stretched in the process, causing problems such as inadequate printing or inability to laminate uniformly. Let's do it.

Other similar biodegradable resins include copolyester resins in which some of the aliphatic dicarboxylic acid components are added as aromatic components during aliphatic polyester polymerization produced by condensation polymerization of aliphatic glycols and aliphatic dicarboxylic acids (hereinafter referred to as aromatic-aliphatic poly Ester resin) is a mixture of aromatic components in order to compensate for the problem of lack of physical properties of aliphatic polyester, and improves physical properties while maintaining biodegradability with the manufacturing method described in the publications of KR10-1999-005816 and WO96 / 25448. The production method is shown.

However, copolymers of aromatic-aliphatic polyesters exhibit rubbery properties and no improvement in cutting properties in the manufacturing process is noticeable. In addition, when forming the blown film alone, there is a problem that the inner surfaces of the film stick to each other, there are various problems such as not gently released from the roll during the secondary processing such as printing.

On the other hand, packaging of electronic and electrical materials requires packaging materials subjected to so-called antistatic treatment, and recently, materials having excellent antistatic capability have also been desired in order to prevent a large capacity of semiconductors and electrostatic destruction of precision components.

The surface resistivity, which is an antistatic level, is usually 10 ¹⁰ to 10 ¹² Ω / sq., And electrical characteristics required for packaging applications such as trays are 10 ¹⁰ Ω / sq. It is a trend that requires the following characteristics.

Among the biodegradable resins, hydrophilic resins include cellulose acetate, polycaprolactone, polyvinyl alcohol, and the like, and these have functional antistatic properties. However, since the antistatic property depends on the environmental humidity, the antistatic performance sometimes changes.

Moreover, the method of providing an antistatic function and stabilizing by adding electroconductive fillers, such as carbon black, is also proposed. However, when the conductive filler is used, since the color tone is limited to black only, when used as a packaging material, there is a problem such that the identification of the internal product is difficult or the molding process is difficult and the resistance value varies depending on the molding situation. In addition, generally, the case of adding carbon black to a biodegradable resin is also reported that the biodegradation function is reduced.

Examples of preparation using biodegradable materials are disclosed in Japanese Patent Laid-Open No. 9-263690, Japanese Patent Laid-Open No. 11-039945, and the like. However, in these preparations, since the conductive filler needs to be mixed in a relatively large amount, the material itself becomes hard and fragile, and since the product color is limited to black, internal identification is impossible when used as a packaging material. In particular, there is a problem in that the antistatic properties are impaired by physical action during the stretching process. In addition, in the case of imparting antistatic properties by adding a surfactant to the biodegradable resin material, there were problems of durability, effects such as durability of effects, fluctuation of expression time, dependence on environmental humidity, and use environment.

To solve this problem, Japanese Patent Laid-Open No. 2002-0091198 proposes a method of adding antistatic properties by adding metal salts composed of cations and anions to biodegradable materials. LiClO ₄ , NaClO ₄ , Mg (ClO ₄ ) ₂ , KClO ₄ , (CF ₃ SO ₃ ) Li, (CF ₃ SO ₂ ) ₂ NLi, (CF ₃ SO ₂ ) ₂ NNa, (CF ₃ SO ₂ ) ₃ CLi, (CF ₃ SO ₂ ) ₃ CNa It has been described to use such substances as antistatic agents. As biodegradable materials, mention has been made of polylactic acid or its application to aliphatic polyesters having a glass transition temperature of less than 30 ° C. However, there is no mention of processability or mechanical properties of the prepared composition.

In addition, there is no biodegradable feature, but in a similar manner, Korean Patent Publication No. 1998-021395 discloses a composition prepared by dispersing a polyalkylene glycol and an ionic organic compound in glycol in a conventional aromatic polyester and polymerizing them together. There is a description of polyester yarns. However, this is suitable for polyester yarns, and it is a field that does not require the movement of the antistatic material to the product surface. When the film or molded product is manufactured, it is due to the high glass transition temperature of the aromatic polyester itself to the product surface. There is a problem that the antistatic effect is inferior because it is not easy to move.

Accordingly, an object of the present invention is to solve this problem, and to synthesize an oligomer by mixing an antistatic component such as an ionic organic compound, polyalkylene glycol, etc. during the ester reaction of an aromatic-aliphatic polyester resin having biodegradable properties. Next, a molten polylactic acid is mixed with the synthesized oligomer to perform a polymerization reaction to provide a copolyester with improved cutting property.

The present invention relates to a polylactic acid containing 30 to 70 parts by weight of an aromatic-aliphatic polyester oligomer synthesized by mixing an antistatic material such as an ionic organic compound or polyalkylene glycol in the form of a glycol slurry during an ester reaction of an aromatic-aliphatic polyester resin. 70 ~ 30 parts by weight of the antifoaming agent, antioxidants, etc. are dispersed in a mixed form of glycol and the polymerization reaction is carried out. The antistatic material is 0.1-10 to 100 parts by weight of the mixed composition of aromatic-aliphatic polyester and polylactic acid. It is characterized by a weight part.

In addition, a plasticizer, a nucleating agent, an antiblocking agent, a crosslinking agent, or the like may be added to add functionality to the present resin composition.

The aromatic-aliphatic polyester used in the present invention is an aromatic component of dicarboxylic acid or derivative thereof of OOC-Ar-COOR '(R, R' is hydrogen or alkyl group) structure, terephthalic acid, phthalic acid, isophthalic acid, naphthalene 2, 6-dicarboxylic acid, diphenylsulfonic acid dicarboxylic acid, diphenylmethanedicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxyethanedicarboxylic acid, cyclohexanedicarboxylic acid, or these At least one member selected from the group consisting of alkylene esters, and an aliphatic dicarboxylic acid or derivative thereof has a structure of ROOC (CH ₂ ) _n COOR '(R, R' is hydrogen or an alkyl group, n is 2-14). At least one member selected from the group consisting of succinic acid, glutaric acid, malonic acid, oxalic acid, adipic acid, sebacic acid, azelaic acid, nonanedicarboxylic acid and alkyl or aryl ester derivatives thereof, and glycols are HO- ( CH ₂ ) Ethylene with _n -OH (n is 2 or more) structure Glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol 1,6-hexanediol or propylene glycol, 1,4-cyclohexanediol, hexamethylene glycol, polyethylene 5 glycol, triethylene glycol 1,2-propanediol which is an aliphatic dihydric alcohol which can form the branched structure represented by the group which consists of alkylene glycol and polyalkylene glycol consisting of neopentyl glycol, tetramethylene glycol, and the following general formula (1) , 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1, Group consisting of 4-hexanediol, 1,5-hexanediol, 1,2-octanediol, 1,3-octanediol, 1,4-octanediol, 1,5-octanediol, 1,6-octanediol, and the like This can be used.

(One)

In said general formula (1), R <_1> is a C2-C8 alkylene group and R <_2> is a C2-C8 alkyl group.

In the aromatic-aliphatic polyester component, the aromatic component should be adjusted to 10-50 mol%, preferably 30 mol% is the best. If the aromatic content is 10 mol% or less, the rubbery properties required in the present resin composition are weakened, and the elastic modulus is lowered.

The polylactic acid used consists of L-lactic acid, D-lactic acid or L, D-lactic acid, with a molecular weight of at least 10,000. These polylactic acids may be used alone or in combination.

Ionic organic compounds are composed of cations, which are alkali metals or alkaline earth metals, and anions that can be formed by ion dissociation, and metal salts represented by formula (2) or (3) or ammonium represented by formula (4). At least one selected from the compounds is preferably dodecylbenzene sulfonate sodium salt.

                   (2) (3)

In the general formulas (2) and (3), R and R` are C1 to C30 alkyl or aryl groups, M is an alkali metal or alkaline earth metal such as Li, Na, K, Mg, Ca, and n is 1-. 2,

                                  (4)

In the general formula (3), R, R`, R``, R``` are C1-C30 alkyl or aryl groups, and X is Cl, Br, or I.

Polyalkylene glycols or derivatives thereof are characterized by a structure represented by HO- (ROR`) n-OH (n is two or more, R, R` is a C2-C8 alkylene group), the average molecular weight is 1,000 ~ All compounds having an antistatic property of 30,000 are possible, preferably polyethylene glycol having a molecular weight of 2,000 to 6,000. These polyalkylene glycols or derivatives thereof interfere with the crystallization of the resin to assist the movement of the antistatic component to the product surface.

Silicone oils are suitable as antifoaming agents, and antioxidants may be used as general antioxidants. Aliphatic glycols, such as ethylene glycol, trimethylene glycol, butylene glycol, are suitable for the glycols, and 100 to 200 parts by weight is preferable with respect to 100 parts by weight of the antistatic material to assist dispersion of the antistatic material.

If the mixing ratio of the polylactic acid is 30 parts by weight or less when the aromatic-aliphatic polyester oligomer is mixed with the polylactic acid, the mechanical properties, transparency, etc. are reduced, and when 70 parts by weight or more, the flexibility is insufficient. A problem arises. The content of the ionic organic compound and the polyalkylene glycol or its derivatives, which have antistatic properties, should be 0.1 to 10 parts by weight based on the mixed composition of aromatic-aliphatic polyester and polylactic acid. Even if this is not obtained and exceeds 10 weight part, the antistatic effect does not fully improve, but, conversely, advancing of crystallization, deterioration of a material, etc., antistatic effect falls.

Since the antistatic material is dispersed and mixed in glycol during the ester reaction of an aromatic-aliphatic polyester, it retains physical bonding strength in the resin and can suppress bleed-out from the surface when manufactured into a molded article, and maintains excellent antistatic property for a long time. do. In addition, the copolymer of the aromatic-aliphatic polyester and the polylactic acid can improve the productivity problem due to the mixing of the polylactic acid to the problem of the cutting defects occurring when the conventional aromatic-aliphatic polyester homopolymerization. If the content of the aromatic-aliphatic polyester oligomer is less than 30 parts by weight of the composition, the flexibility of the resin is insufficient and the content of the polylactic acid resin increases, so that the chip is broken or the shear surface is not smooth when cutting. If it is 70 parts by weight or more, mechanical properties, transparency, etc. are reduced, and the cutting property during the discharging process also does not greatly help.

The antistatic material is added in the form of a slurry dispersed in glycol after the completion of the methanol outflow in the ester reaction of the aromatic-aliphatic polyester, and after the aromatic-aliphatic polyester oligomer having a polymerization degree of less than 10 is synthesized, the polylactic acid resin is melted. Then, the antifoaming agent, antioxidant, and the like are dispersed in glycol and added together to perform a polycondensation reaction.

In addition, for the purpose of improving the secondary processability of these mixtures, plasticizers are compatible with polylactic acid aromatic-aliphatic polyesters and polyolefins as plasticizers, and ether ester plasticizers, oxyacid ester and glycol plasticizers are possible. Examples thereof include ethylene glycol, propylene glycol, polyethylene glycol, sorbitol, glycerin (glycerol), methoxypolyethylene glycol, tri-n-butyl citrate, and the like. It is also possible to mix and use two or more types of these mixtures. Nuclear agents include various general inorganic particles including talc, and the inorganic particles used in the nucleating agent may be used in parallel with an organic lubricant, and as an organic lubricant, an aliphatic hydrocarbon-based lubricant or an aliphatic amide-based lubricant may be used. In addition, a crosslinking agent is used for the purpose of lowering the melt tension during molding into a film. As a crosslinking agent that can be added to the present resin, an organic peroxide compound, a metal complex, an epoxy compound, an isocyanate compound, or the like is used.

The composition may also be added with additives such as sunscreens, antibacterial / deodorants, heat stabilizers, light stabilizers, flame retardants, antistatic agents, antioxidants, pigments and the like, depending on the application.

As described above, the present invention imparts antistaticity to a degradable polyester copolymer having excellent cutting properties and mechanical strength, and utilizes its excellent properties to produce mechanical parts, automobile parts, sports goods, OA equipment, home appliances, electrical appliances, Provided are a practical antistatic polyester copolymer that can be suitably used in products related to antistatic measures, such as in the electronic field, other various components, packages, tubes, coatings, and the like, and a method of manufacturing the same.

The following examples and comparative examples illustrate the invention in more detail, but do not limit the scope of the invention. First, the measurement and evaluation methods necessary for the explanation of the present invention were performed under the following conditions.

 (1) Mechanical Strength (Tensile Strength; ASTM D 882)

Using a tensile tester, the measurement was carried out at a tensile rate of 500 mm / min at a temperature of 20 ± 2 ° C. and a relative humidity of 65 ± 2%. In addition, MD and the width direction were shown for the longitudinal direction of the film by TD.

(2) flexibility (elongation; ASTM D 882)

Elongation until fracture of the film was determined under the same conditions as the tensile strength.

(3) Conductivity (surface specific resistance; ASTM D 257)

The resistivity of the surface was calculated | required using the film specimen of 10 cm x 10 cm.

(4) Cutting property (discharge rate and frequency of trouble)

The cutting operation was performed at a knife speed of 400 RPM in a general USG cutter while supplying N ₂ gas of 4.0 kg / cm 2 to the polymerization reaction tube, and the time until discharge was completed and the number of times of discontinuation due to the defective cutting were measured.

(5) Exploded View (KS M-3100-1)

Compute the test material under the same conditions using TLC grade cellulose with a particle size of 20 µm or less as the standard sample, and calculate the biodegradability of the test material from the cumulative amount of carbon dioxide released for 45 days (using the formula below). In this case, the biodegradability of the test substance was expressed in%.

Dt = [{(CO ₂ ) T- (CO ₂ ) B} / ThCO ₂ ] × 100

(CO ₂ ) T: Accumulated amount of carbon dioxide from a container containing the test substance

(CO ₂ ) B: Accumulated amount of carbon dioxide from containers containing compost

ThCO ₂ : Calculation of Theoretical Carbon Dioxide

ThCO ₂ = MTOT × CTOT × (44/12)

MTOT: Total dry solids (g) of test substance added at the start of the analysis

CTOT: percentage of organic carbon in the total dry solids of the test substance (g / g)

44,12: molecular weight of carbon dioxide and atomic weight of carbon

(Example 1)

The aromatic-aliphatic polyester having an aromatic content of 30 mol% is composed of dimethyl terephthalate, succinic acid, glutaric acid, adipic acid, ethylene glycol, 1,4-butanediol, and synthesizes 30 kg of an oligomer having a polymerization degree of 10 or less through an ester reaction. do. In addition to 30 kg of the aromatic-aliphatic polyester oligomer, after completion of the methanol distillation during the ester reaction, a slurry prepared by dispersing 1 kg of dodecylbenzene sulfonate sodium salt and 1 kg of polyethylene glycol having a molecular weight of 4000 kg 2 kg was added to participate in the reaction. After the completion of the ester reaction, 70kg of Cargill Dow's polylactic acid polymer was mixed with polylactic acid to participate in the condensation polymerization reaction, 0.5kg of silicone oil as an antifoaming agent, and 0.1kg of Irganox 1010 0.1kg of Songwon Industries as an antioxidant. Dispersion is added in 1kg and the condensation polymerization reaction is started. The catalysts used were 25 g of sodium acetate trihydrate, 21 g of calcium acetate hydrate, 32 g of antimony (III) oxide, 46 g of tetrabutyl titanate, 8 g of cobalt (II) acetate tetrahydrate, and zinc acetate dihydrate in an aromatic-aliphatic polyester ester reaction. 10 g of water is added first, followed by reaction. At the same time as the molten polylactic acid is mixed, 46 g of tetrabutyl titanate and 36 g of trimethyl phosphate are further mixed, followed by a condensation polymerization process.

After 3 hours or more of polymerization process, cutting was carried out while supplying 4.0 kg / cm 2 of N ₂ gas to the polymerization reaction tube while quenching with cooling water of 10 ° C. or less. Table 1 shows the time until discharge is completed and the number of trouble occurrences. , 2 is shown. The resulting pellets were sufficiently dehumidified and dried, mixed with 10 kg of methoxy polyethylene glycol as a plasticizer, 5 kg of citrate compound, 0.5 kg of amide-based lubricant, and 0.1 kg of organic peroxide as crosslinking agent, and then blown with a blown film extruder. The production film was prepared. Specimens were prepared from the prepared films to measure tensile strength, elongation, resistance, and resolution, and the results are shown in Tables 1 and 2 below.

(Example 2)

Except that 50kg of aromatic-aliphatic polyester and 50kg of polylactic acid were subjected to the polymerization and cutting in the same manner as in Example 1, and the time until the discharge was completed and the number of troubles are shown in Table 1. In addition, an inflation film having a thickness of 30 μm was prepared in the same manner as in Example 1. Tensile strength, elongation, resistance, and resolution were measured by fabricating specimens from the prepared films, and the results are shown in Table 1.

(Example 3)

Except that 70kg of aromatic-aliphatic polyester and 30kg of polylactic acid were subjected to polymerization and cutting in the same manner as in Example 1, and the time until the discharge was completed and the number of troubles are shown in Table 1. In addition, an inflation film having a thickness of 30 μm was prepared in the same manner as in Example 1. Specimens were prepared from the prepared films to measure tensile strength, elongation, resistance, and resolution, and the results are shown in Table 1.

(Example 4)

Example 1 except that 0.05 kg of dodecylbenzene sulfonate sodium salt, 0.05 kg of polyethylene glycol having a molecular weight of 4000, 0.025 kg of silicone oil as an antifoaming agent, and 0.15 kg of ethylene glycol dispersed in 0.005 kg of Irganox 1010 of Songwon Industries as an antioxidant The polymerization and cutting were carried out in the same manner as in Table 2 and the time until the discharge was completed and the number of troubles are shown in Table 2. In addition, an inflation film having a thickness of 30 μm was prepared in the same manner as in Example 1. Specimens were prepared from the prepared films to measure tensile strength, elongation, resistance, and resolution, and the results are shown in Table 2.

(Example 5)

The same method as in Example 1, except that 5 kg of dodecylbenzene sulfonate sodium salt, 5 kg of polyethylene glycol having a molecular weight of 4000, 2.5 kg of silicone oil as an antifoaming agent, and 15 kg of ethylene glycol in which 0.5 kg of Irganox 1010 in Songwon Industries were dispersed as an antioxidant The polymerization reaction and the cutting work were carried out. Table 2 shows the time until the discharge is completed and the number of troubles. In addition, an inflation film having a thickness of 30 μm was prepared in the same manner as in Example 1. Specimens were prepared from the prepared films to measure tensile strength, elongation, resistance, and resolution, and the results are shown in Table 2.

(Comparative Example 1)

Except that 10kg of aromatic-aliphatic polyester and 90kg of polylactic acid were used, polymerization and cutting were carried out in the same manner as in Example 1, and the time until the discharge was completed and the number of troubles are shown in Table 1. In addition, an inflation film having a thickness of 30 μm was prepared in the same manner as in Example 1. Tensile strength, elongation, resistance, and resolution were measured by fabricating specimens from the prepared films, and the results are shown in Table 1.

(Comparative Example 2)

Except that 90kg of aromatic-aliphatic polyester and 10kg of polylactic acid were used, polymerization and cutting were performed in the same manner as in Example 1, and the time until discharge was completed and the number of troubles are shown in Table 1. In addition, an inflation film having a thickness of 30 μm was prepared in the same manner as in Example 1. Tensile strength, elongation, resistance, and resolution were measured by fabricating specimens from the prepared films, and the results are shown in Table 1.

(Comparative Example 3)

30 kg of aromatic-aliphatic polyester consisting of dimethyl terephthalate, succinic acid, glutaric acid, adipic acid, ethylene glycol, 1,4-butanediol, 70 kg of polylactic acid, 10 kg of methoxypolyethylene glycol as a plasticizer as other additives, tri-n- Example except that 5 kg of butyl citrate, 20 kg of talc as a nucleating agent, 0.5 kg of Bohenamide as an amide lubricant, and 0.1 kg of 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane as a crosslinking agent The polymerization and cutting were carried out in the same manner as 1, and the time until the discharge was completed and the number of troubles are shown in Table 1. In addition, an inflation film having a thickness of 30 μm was prepared in the same manner as in Example 1. Specimens were prepared from the prepared films to measure tensile strength, elongation, resistance, and resolution, and the results are shown in Table 1.

(Comparative Example 4)

Polymerization was carried out in the same manner as in Example 1 except that 10 kg of dodecylbenzene sulfonate sodium salt, 10 kg of polyethylene glycol having a molecular weight of 4000, 5 kg of silicone oil as an antifoaming agent, and 30 kg of ethylene glycol in which 1 kg of Irganox 1010 of Songwon Industrial Co. Reaction and cutting were performed, and the time until discharge is completed and the number of trouble occurrence are shown in Table 2. In addition, an inflation film having a thickness of 30 μm was prepared in the same manner as in Example 1. Specimens were prepared from the prepared films to measure tensile strength, elongation, resistance, and resolution, and the results are shown in Table 2.

TABLE-1

TABLE-2

As can be seen from the above examples and comparative examples, the biodegradable polymer prepared by the method of preparing a polyester copolymer according to the present invention has excellent cutting property with water, and thus has high productivity, and has similar processability and mechanical strength as those of conventional plastics. It is possible to have applications in various fields where antistatic properties are required.

Claims (8)

Three-component polyester air composed of 0.1 to 10 parts by weight of an antistatic material selected from the group consisting of 30 to 70 parts by weight of an aromatic-aliphatic polyester oligomer, 70 to 30 parts by weight of a polylactic acid, an ionic organic compound and a polyalkylene glycol or a derivative thereof. coalescence. The aromatic-aliphatic polyester according to claim 1, wherein the aromatic-aliphatic polyester is at least one selected from dicarboxylic acids or derivatives thereof having a structure of ROOC-Ar-COOR '(R, R' is hydrogen or an alkyl group) as an aromatic component. ROOC (CH ₂ ) _n COOR '(R, R' is one or more selected from dicarboxylic acid or derivative thereof having a hydrogen or alkyl group, n is 2 to 14) structure, and glycols are HO- (CH ₂ ) _n A polyester copolymer characterized in that a group consisting of a diol or polyalkylene glycol having a structure of -OH (n is 2 or more) or an aliphatic dihydric alcohol having a structure represented by the following general formula (1) is used:                                      (One) In said general formula (1), R <_1> is a C2-C8 alkylene group and R <_2> is a C2-C8 alkyl group. The polyester copolymer according to claim 1, wherein the polylactic acid is composed of L-lactic acid, D-lactic acid or L, D-lactic acid, and has a molecular weight of 10,000 or more. The said ionic organic compound is at least 1 sort (s) chosen from the metal salt represented by following General formula (2) or (3), and the ammonium compound represented by following General formula (4), The said polyalkylene The glycol or derivative thereof is a biodegradable polyester copolymer, characterized in that the structure is represented by HO- (ROR`) n-OH (n is at least 2, R, R` is an alkyl group of C2 ~ C8):                      (2) (3) In the general formulas (2) and (3), R and R` are C1 to C30 alkyl or aryl groups, M is an alkali metal or alkaline earth metal such as Li, Na, K, Mg, Ca, and n is 1-. 2,                                    (4) In the general formula (3), R, R`, R``, R``` are C1-C30 alkyl or aryl groups, and X is Cl, Br, or I. The polyester copolymer according to claim 1, wherein the copolymer has a shape of a film, a fiber, or a molding. The molten PLA resin is mixed with an oligomer prepared by mixing an antistatic component selected from an ionic organic compound and a polyalkylene glycol or a derivative thereof in an ester reaction of an aromatic-aliphatic polyester, and then performing a polymerization reaction together. Method for producing a polyester copolymer. 7. The method according to claim 6, wherein the ionic organic compound and the polyalkylene glycol or derivative thereof are used in the form of dispersed in a glycol mixed with an antifoaming agent, an antioxidant, and the like. 7. The method of claim 6, wherein the oligomer of the aromatic-aliphatic polyester is prepared at a polymerization degree of 10 or less.