JP2002226688A - Biodegradable polyester resin composition and film thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable polyester resin composition and film thereof having excellent properties of molding processability, such as T-die extrusion molding or inflation molding, and film tearing resistance. SOLUTION: The biodegradable polyester resin composition consisting of a polycondensed polyester, a high molecular weight polycaprolactone having melt viscosity of 10,000 to 50,000 poise, and a low molecular weight polycaprolactone having melt viscosity of 1,000 to 3,000 poise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable polyester resin composition comprising a polycondensed polyester, a high molecular weight polycaprolactone and a low molecular weight polycaprolactone, and a molding process obtained by inflation molding or T-die extrusion molding. The present invention relates to a biodegradable film having improved properties and tear strength (including a sheet in the present invention).

[0002]

2. Description of the Related Art In recent years, environmental issues have been receiving more and more attention. As a result, energy saving, recycling of resources, and development of environmentally friendly products, particularly products having biodegradability, have been increased. I have. For biodegradable products, for example, a biodegradable resin is used, and thus research is being actively conducted. According to the definition of the Biodegradable Plastics Research Group, biodegradable resins are `` having the same physical properties as general-purpose plastics during use, but once disposed of, they are degraded and assimilated by the action of microorganisms in the natural environment. And eventually break down into water and carbon dioxide. ''
It is pointed out that.

At present, as biodegradable plastics, polymers produced by microorganisms such as Biopol (polymers such as 3-hydroxybutyric acid and 3-hydroxyvaleric acid) manufactured by Monsanto Co., Ltd., Daicel Chemical Industries, Ltd. Polymers derived from natural products such as Cell Green (cellulose acetate (PCA) type), Bionole (polybutylene succinate, polybutylene succinate adipate, etc.) manufactured by Showa Kogyo Co., Ltd., Daicel Chemical Industries, Ltd. Cell Green (polycaprolactone), Mitsui Chemicals, Inc.
Chemically synthesized polymers such as Laceia (polylactic acid type) are known. Among them, the most actively developed are chemically synthesized polymers, but these are in the stage of development, and those that can sufficiently satisfy practical physical properties while maintaining biodegradability are not yet developed. Almost no. In addition, the applications of biodegradable plastics currently being tested are mainly film applications such as agricultural films, compost bags, and garbage bags. However, it is still insufficient to combine both the biodegradability of the film and the physical properties of general-purpose resins.For example, although the biodegradability is excellent, the physical properties are poor, Degradability is often insufficient. In particular, physical properties are often inferior to biodegradability.

[0004]

Considering film applications, the first problem is whether molding processes such as T-die extrusion molding and inflation molding can be performed at the same level as general-purpose resins, and furthermore, the physical properties of the film, especially tearing A second problem is whether or not one having sufficient strength can be obtained. The purpose of the present invention is
An object of the present invention is to provide a biodegradable film excellent in both moldability and film tear strength and a resin composition used therefor.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the polycondensed polyester (A) has a melt viscosity of 10,
A mixture of polycaprolactone (B (H)) having a high melt viscosity of 000 to 50,000 poise (measured by a rheometer) has a melt viscosity of 1,000 to 3,000 poise.
By adding a low melt viscosity polycaprolactone (B (L)) (measured by a rheometer), it was found that such a problem could be solved, and the present invention was completed.

That is, the first of the present invention is a polycondensation polyester (A) having a melt viscosity of 10,000 to 50,000 p.m.
high molecular weight polycaprolactone (B (H)) having a melt viscosity of 1,000 to 3,
A biodegradable polyester resin composition comprising a low molecular weight polycaprolactone (B (L)) having a molecular weight of 000 poise (measured by a rheometer). The second aspect of the present invention is that B (H) /
The biodegradable polyester resin composition according to the first aspect of the present invention, wherein the weight ratio of B (L) is 90/10 to 10/90. A third aspect of the present invention is to provide the biodegradable polyester resin composition according to the first or second aspect of the present invention, wherein the weight ratio of (B (H) + B (L)) / A is 10/90 to 70/30. provide. The fourth aspect of the present invention is a high molecular weight polycaprolactone (B (H))
And the low-molecular-weight polycaprolactone (B (L)) is a polycaprolactone synthesized by ring-opening polymerization of ε-caprolactone. . The fifth of the present invention
Is a copolymer having a structure in which a polycondensed polyester (A) is obtained by polycondensation of 1,4-butanediol and succinic acid, or polycondensation of 1,4-butanediol and succinic acid and adipic acid. The biodegradable polyester resin composition according to any one of the first to fourth aspects of the present invention is provided.
A sixth aspect of the present invention provides the biodegradable polyester resin composition according to any one of the first to fifth aspects of the present invention, further comprising an inorganic additive (D). A seventh aspect of the present invention provides the biodegradable polyester resin composition according to the sixth aspect, wherein the inorganic additive (D) is talc and / or calcium carbonate. An eighth aspect of the present invention provides the biodegradable polyester resin composition according to any one of the first to seventh aspects of the present invention, further comprising a copolymerized polyester (C).
A ninth aspect of the present invention is that the copolymerized polyester (C) comprises ethylene glycol and / or 1,4-butanediol as a diol component, terephthalic acid as a dicarboxylic acid component,
The succinic acid and / or adipic acid and ε-caprolactone as a lactone component are used to form a copolymer having a structure obtained by random polycondensation of a diol component, a dicarboxylic acid component and a lactone component. The invention provides a biodegradable polyester resin composition as described above. A tenth aspect of the present invention provides a film comprising the biodegradable polyester resin composition according to any one of the first to ninth aspects of the present invention. An eleventh aspect of the present invention provides the film according to the tenth aspect of the present invention obtained by T-die molding or inflation molding.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Polycondensed polyester (A) The polycondensed polyester (A) used in the present invention includes:
Although not particularly limited, an aliphatic polyester having a melting point of 100 ° C. or more and having thermoplasticity is preferred.
The monomers constituting the polycondensed polyester (A) include aliphatic dicarboxylic acids having 4 to 10 carbon atoms and 2 to 2 carbon atoms.
10 aliphatic diols. Examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, adipic acid and the like. Examples of the aliphatic diol include ethylene glycol (EG) and 1,4-butanediol (1,4-B
G), neopentyl glycol (NPG) and the like. Examples of the polycondensed polyester (A) include a polyester resin obtained from succinic acid and 1,4-butanediol, a polyester resin obtained from succinic acid and 1,4-butanediol, and succinic acid, adipic acid and 1,4-butane. Polyester resins obtained from diols, polyester resins obtained from oxalic acid and neopentyl glycol, polyester resins obtained from oxalic acid and 1,4-butanediol, and polyester resins obtained from oxalic acid and ethylene glycol can be exemplified. Particularly preferred is a polyester resin obtained from succinic acid and 1,4-butanediol. These may be polyesters having a structure obtained by polycondensation of a diol component and a dicarboxylic acid component, and dehydration direct polycondensation of a diol component and a dicarboxylic acid component, dehydrochlorination direct polycondensation of a diol component and a dicarboxylic acid chloride, It may be obtained by a transesterification reaction between a diol component and a dicarboxylic acid alcohol ester. The number average molecular weight of the polycondensed polyester resin (A) is 20,000 or more, preferably 40,000 or more.
000 or more, and there is no particular upper limit.
Those of about 00,000 can also be used.

As the polycondensed polyester resin (A) used in the present invention, a resin containing a urethane bond can be used. The polycondensed polyester resin containing a urethane bond is obtained by increasing the molecular weight of the polycondensed polyester resin, preferably by using an aliphatic diisocyanate compound. Examples of the aliphatic diisocyanate compound include hexamethylene diisocyanate, lysine diisocyanate methyl ester {OCN- (CH _{2) 4} -CH
(—NCO) (— COOCH ₃ )}, trimethylhexamethylene diisocyanate and the like are exemplified, and among them, hexamethylene diisocyanate is preferable. The number average molecular weight of the polycondensed polyester resin containing a urethane bond is preferably 20,000 or more, more preferably 4 or more.
It is in the range of not less than 000.

Polycaprolactone The high molecular weight polycaprolactone (B) used in the present invention
As (H)) and low molecular weight polycaprolactone, those obtained by subjecting caprolactone to ring-opening polymerization of caprolactone by a conventional method using an active hydrogen-containing compound such as an alcohol as an initiator can be used. The functional number of the initiator is not particularly limited, and bifunctional or trifunctional ones can be preferably used. The polycaprolactone used is ε
In addition to the homo-ring-opening polymer of caprolactone, a copolymer containing a comonomer constituent unit such as valerolactone, glycolide, or lactide, for example, 20 mol% or less can also be used.

The number average molecular weight of the high molecular weight polycaprolactone (B (H)) used in the present invention is from 60,000 to 15
0,000, preferably 60,000-70,000. Furthermore, the melt viscosity of the high molecular weight polycaprolactone measured by rheometer is 10,000 to 50,000.
poise, preferably 20,000-40,000p
oise. When the high molecular weight polycaprolactone is used, both mechanical properties and biodegradability can be highly balanced.

The number average molecular weight of the low molecular weight polycaprolactone (B (L)) used in the present invention is from 10,000 to 5
000, preferably 30,000 to 50,000. Furthermore, the melt viscosity of the low molecular weight polycaprolactone measured by rheometer is 500 to 3,000 pois.
e, preferably 1,000 to 1,500 poise. When a low molecular weight polycaprolactone is used, the melt viscosity of the resin composition is adjusted, and advantages such as improved moldability and mechanical properties appear.

The high molecular weight polycaprolactone (B (H)) used in the present invention is PCLH7 (homopolymer, Mn about 70,000, melt viscosity 35,000 poise (210 ° C., 210 ° C.) manufactured by Daicel Chemical Industries, Ltd.). Rheometer measurement)) etc. are low molecular weight polycaprolactone (B (L))
PCLH5 (homopolymer, Mn about 50,000
0, melt viscosity 1,800 poise (210 ° C., measured by rheometer)), PCLH1 (homopolymer, Mn about 1)
000, and a melt viscosity of 700 poise (210 ° C., measured by rheometer).

The high molecular weight polycaprolactone (B)
(H)) and the low molecular weight polycaprolactone (B (H)) have a weight ratio B (H) / B (L) of 90/10 to 10/90, preferably 8/10.
0/20 to 40/60. The sum of B (H) and B (L) is 100. If the ratio of B (H) is too large, the melt viscosity cannot be reduced and the flowability cannot be adjusted, so that the moldability and tear strength are insufficiently improved. The fluidity becomes too high, and the heat resistance and mechanical properties of the molded body are reduced.

The weight ratio of the sum of high molecular weight polycaprolactone (B (H)) and low molecular weight polycaprolactone (B (L)) to polycondensed polyester (A) (B (H) + B (L)) / A
Is 10 / 90-70 / 30, preferably 30 / 70-
50/50. Note that the sum of (B (H) + B (L)) and A is 100. If the ratio of the polycondensed polyester (A) is too large, the biodegradation time will be too long and the merit as a biodegradable resin will be poor. If it is too small, practical heat resistance will not be exhibited.

Copolyester (C) The copolyester (C) can be added to the biodegradable polyester resin composition of the present invention, if necessary. The copolymerized polyester (C) is not particularly limited, but a copolymerized polyester resin having at least one, preferably at least two, of monomer units constituting the aliphatic polyester (A) and polycaprolactone is used. Or three or more types. For example, when polybutylene succinate (PBS) obtained by polycondensation of 1,4-BG and succinic acid and polycaprolactone (PCL) are blended, 1,4-BG, which is a monomer constituting PBS, and succinic acid are used. A copolymerized polyester obtained by copolymerizing other ester monomers together, or a copolymerized polyester obtained by combining other ester monomers with ε-caprolactone, which is a monomer constituting PCL, and both of them, that is, 1,
A copolymer obtained by copolymerizing 4-BG, succinic acid, and CL together (abbreviated as P (BSCL)) or the like has an effect of improving the tear strength without impairing the biodegradability. The monomer constituent unit of the copolymerized polyester (C) is the above P
In the example of (BSCL), there are a 1,4-butylenedioxy group, a succinyl group, and a 5-oxycaproyl group, and the monomers that provide the monomer structural units are BG, succinic acid, and CL, respectively.

The monomers constituting the copolymerized polyester (C) include the aliphatic polyester (A) as described above.
What gives at least one of the monomer structural units constituting the polymer of polylactone and polylactone may be used. Therefore, aromatic dicarboxylic acids such as terephthalic acid and parahydroxybenzoic acid, and aromatic hydroxycarboxylic acids can be used as other monomers. As the charge composition, diol 1 to 1 mol per 1 mol of dicarboxylic acid was used.
2 moles and 0.1 to 10 moles of lactone, preferably 1.1 to 1.5 moles of diol and 0.5 to 2 moles of lactone. Examples of such a copolymerized polyester include, for example,
A random copolymer of a copolymer (abbreviated as P (BTCL)) obtained by terpolymerizing 1,4-BG, terephthalic acid and CL (Perprene series manufactured by Toyobo Co., Ltd.) ) Or a block copolymer or the above P (B, S, C
L) a random copolymer or a block copolymer.

The proportion of the copolymerized polyester (C) is 0 parts by weight based on 100 parts by weight of the total of the aliphatic polyester (A) and the two kinds of polycaprolactone (A + (B (H) + B (L))). 0.5 to 50 parts by weight, preferably 1 to 10 parts by weight. Thereby, the tear strength of the film is improved. However, when the copolymerized polyester (C) does not have biodegradability in a biodegradation test described below, the amount of addition is limited to 1 part by weight or less.

Inorganic Additive (D) The inorganic additive (D) used in the present invention is not particularly limited. For example, talc, calcium carbonate, mica, calcium silicate, titanium oxide, glass fiber, porcelain clay (Calcination), white carbon and the like, and preferably talc or calcium carbonate. These can be used as a mixture of two or more. By adding the inorganic additive, the tear strength is further improved, and the moldability is also improved. The addition ratio of the inorganic additive is 0 to 100 parts by weight, preferably 1 part by weight, based on 100 parts by weight of the total (A + (B (H) + B (L)) + C) of the resin components. More preferably, it is 10 to 40 parts by weight. When the addition ratio of the inorganic additive exceeds 100 parts by weight,
When a film or sheet is used, its elongation is extremely reduced, and practical properties cannot be maintained. If the amount is less than 1 part by weight, the effect of improving the tear strength may not be sufficient.

The biodegradable resin composition of the present invention may contain, as necessary, other components such as solid lubricants, liquid lubricants, starch, wood powder, carbon black, and other biodegradable resins (polylactic acid). , PVA, etc.) can be added. The lubricant is not particularly limited, and specific examples thereof include hydrocarbons such as liquid paraffin, fatty acids such as higher fatty acids, fatty acid amides such as stearamide, and alcohols such as glycerin. The amount of lubricant added is
(A) + (B) (that is, (B (H) + B (L))) +
0 to 5 parts by weight, preferably 0.1 to 3 parts by weight, particularly preferably 0.3 to 0.7 parts by weight, based on 100 parts by weight in total of (C) + (D).

The kneading method of the aliphatic polyester (A), the polycaprolactone (B), the copolymerized polyester (C), the inorganic additive (D), and the above-mentioned other components to be added as required, is a general method. The method can be preferably used. Specifically, each raw material resin pellets, powders, solid flakes and the like are dry-mixed with a Henschel mixer or a ribbon mixer, and are well-known in the art such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader, and a mixing roll. It can be supplied to a melt mixer and melt-kneaded.

The biodegradable resin composition obtained as described above is formed as it is or preferably in the form of a pellet into a film (in the present invention, a film including a sheet is also referred to as a film). The method for forming the film is not particularly limited, and a conventional method can be used. Specific examples include inflation molding, T-die extrusion molding, and calendar molding, and preferably inflation molding or T-die extrusion molding. Even if the film is not stretched,
Uniaxial stretching or biaxial stretching may be used. When stretching,
The stretching ratio is 1 to 20 times, preferably 2 to 5 times. The tear strength of the film of the present invention is 60
g / 20 μm or more, preferably 100 g / 20 μm or more.

The method for evaluating the biodegradability of a film sample obtained from the biodegradable polyester resin composition is described in JIS.
There are various methods using activated sludge according to K6950, burial in soil, immersion in seawater or rivers, evaluation in compost, etc., but in the examples, there is a correlation with the degradability in general fields This is performed according to JIS K6950. The biodegradable polyester resin composition provided by the present invention has a degradation rate of 60% or more after cultivation in municipal sewage standard sludge specified in JIS K6950 below for 4 weeks,
Preferably it is more than 80%. Further, the biodegradable polyester resin composition provided by the present invention can be used for a wide range of applications including films as an alternative to conventional polyethylene and other polyolefins.
In particular, it is preferable to use it for film applications that are easily left in the environment.

[0023]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. The raw materials used were as follows, and the resin raw materials were dried (60 ° C. × 10 hours or more) before being used for molding. PCL H7: High melt viscosity polycaprolactone manufactured by Daicel Chemical Industries, Ltd., number average molecular weight: 70,000 PCL H5: Low melt viscosity polycaprolactone manufactured by Daicel Chemical Industries, Ltd., number average molecular weight: 50,000 # 1903: Showa Polycondensed polyester resin Bionoll # 1903, polybutylene succinate, number average molecular weight # 70,000 # 3001: polycondensed polyester resin Bionoll # 3001, polybutylene succinate adipate manufactured by Showa Polymer Co., Ltd. , Number average molecular weight: 70,000 Perprene S1002: butanediol / terephthalic acid / caprolactone random copolymer manufactured by Toyobo Co., Ltd., number average molecular weight: 100,000 Hytron A: talc manufactured by Takehara Chemical Co., Ltd., average particle size 3 .
3 μm

[Production of Compound and Pellets] The above-mentioned raw materials were blended in a ratio (parts by weight) shown in Table 1 using a tumbler, and then compounded with a twin-screw extruder under the following extrusion conditions to produce pellets. <Extrusion conditions> C1 (under hopper): 100 ° C C2: 180 ° C C3: 200 ° C C4: 200 ° C C5: 200 ° C C6: 210 ° C C7: 210 ° C AD: 210 ° C (adapter) D: 200 ° C (die) The numbers 1 to 7 of C increase from the bottom of the hopper of C1 toward the die. The same applies to the numbering of the film forming step. The resin supplied from the hopper is extruded from C1 to D and then cut by a pelletizer.

[Formation of Film] A film was formed using the above pellets. The method for forming a film is not particularly limited, and an inflation molding method or a T-die extrusion molding method can be used. In Examples and Comparative Examples, the film was formed using the inflation molding method. The molding conditions are as follows. <Inflation molding conditions> C1 (under hopper): 100 ° C C2: 180 ° C C3: 200 ° C C4: 200 ° C C5: 210 ° C C6: 210 ° C AD: 210 ° C (adapter) D1: 210 ° C (die) D2: 210 C. The pellets supplied from the hopper are extruded from C1 in the direction D, and are extruded upward in the die D, expanded into a cylinder by air pressure, and formed into a film. Film take-off speed: 17.0-25.0 m / min Lip width: 2.0 mm Film width: 1,350 mm Film thickness: 20 μm

Examples and Comparative Examples The films thus obtained were used as agricultural multi-films. Perform the following various evaluations using the above pellets and films,
The results are shown in Table 1. [Evaluation of hand tearability] Based on the feeling of tearing by hand a cut in a polyethylene film (inflation molding) widely used as a general-purpose film at present (10
The scores when each of the films obtained above were torn by hand were evaluated out of 10 points. The lower the score, the less resistance to the hand when tearing, and the cross-section of the tear does not undulate. As a criterion at this time, not only the strength but also the overall tearability was sensually evaluated, such as the resistance transmitted to the hand when the hand was torn, how to tear (with or without linearity), the waving of the tear surface, and the like. The evaluation criteria for the sensory evaluation are as follows. ：: The tearing surface is wavy, also tears diagonally, and has a large tear resistance. ：: The tear surface is straight and has little undulation but large tear resistance. X: The tear surface is linear and the tear resistance is small. XX: Those with a smaller tear resistance and easier to propagate tear than X. [Tear strength] Sample: Each film obtained above was applied with a width of 2
It was cut into 5 mm and 100 mm in length (MD direction), and a 30 mm cut in the length direction from the center at one end of the width was used. The sample was conditioned in a constant temperature and humidity room at 23 ° C. × 50% RH for 24 hours and used for measurement. <Tear strength measurement conditions> Sample length (distance between chucks): 30 mm Equipment used: OLIENTEC, RTA-500 Load cell: 5 kgf, 20% Crosshead speed: 500 mm / min Number of tests: n = 3 (n = 3 (The results were averaged.) The evaluation criteria for the sensory evaluation are as follows. ：: Strong tear strength, tears diagonally, and tear surface is wavy. ：: Strong tear strength, linear tear surface, wavy tear surface. X: The tear strength is weak and the tear surface is linear. XX: The tear strength is very weak, the tear surface is linear, and the tear surface has almost no waviness. [Tensile test] Each of the films obtained above was subjected to JIS K-7
A tensile test was performed using a punched piece of No. 2 dumbbell based on No. 113. The film was punched in both MD and TD directions. Sample is 23 ° C
The humidity was adjusted in a constant temperature and humidity chamber of × 50% RH for 24 hours, and the sample was subjected to measurement. The measurement conditions are as follows. <Measurement conditions for tensile test> Sample length (distance between chucks): 80 mm Equipment used: OLIENTEC, RTA-500 Load cell: 10 kgf, 40% Crosshead speed: 500 mm / min Number of tests: n = 3 (n = 3 [Results were averaged] [Evaluation of processability] The pellets of each compound obtained above were formed into 3 mmφ strands using a single-screw extruder, and cut into appropriate lengths, and the uniaxial elongational viscosity was determined as a sample. It was measured. At this time, whether or not each sample had strain hardening property and the degree of the strain hardening property were subjected to a sensory evaluation of the moldability. A: Strain hardening is very large and inflation molding is possible. ：: Strain hardening property, to a lesser extent, but capable of inflation molding. ×: No strain hardening property, and inflation molding is impossible. [Biodegradability] Simple degradation test using sludge (JIS K-
The biodegradability was evaluated according to 6950). Himeji standard activated sludge was used to measure biodegradability (% by weight) 28 days after the test period. The biodegradability value obtained above was 60% or less, and X was 60% or more.
Those with 0% or more were indicated by ◎.

[0027]

[Table 1]

[0028]

According to the present invention, a biodegradable film having excellent biodegradability, moldability and physical properties, particularly, excellent tear strength can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA43 AA44 AB30 AF15Y AF16Y AH01 AH04 BB06 BB09 BC01 BC12 4J002 CF031 CF192 CF193 DE136 DE236 DJ006 DJ046 DJ056 DL006 DM006 FA046 FD016 GA01 GG02

Claims (11)

[Claims] 1. A polycondensed polyester (A), a high molecular weight polycaprolactone (B (H)) having a melt viscosity of 10,000 to 50,000 poise (measured by a rheometer), and a melt viscosity of 1,000 to 3, 000 poise (measured by rheometer) low molecular weight polycaprolactone (B
(L)) a biodegradable polyester resin composition. 2. The weight ratio of B (H) / B (L) is 90 / 10-1.
The biodegradable polyester resin composition according to claim 1, wherein the ratio is 0/90. 3. The weight ratio of (B (H) + B (L)) / A is 10 /
The biodegradable polyester resin composition according to claim 1, wherein the composition is 90 to 70/30. 4. High molecular weight polycaprolactone (B (H))
The biodegradable polyester resin composition according to any one of claims 1 to 3, wherein the low molecular weight polycaprolactone (B (L)) is a polycaprolactone synthesized by ring-opening polymerization of ε-caprolactone. 5. The polycondensed polyester (A) is 1,4-
The raw material according to any one of claims 1 to 4, which is a copolymer having a structure obtained by polycondensation of butanediol and succinic acid, or polycondensation of 1,4-butanediol with succinic acid and adipic acid. Degradable polyester resin composition. 6. The biodegradable polyester resin composition according to claim 1, further comprising an inorganic additive (D). 7. The biodegradable polyester resin composition according to claim 6, wherein the inorganic additive (D) is talc and / or calcium carbonate. 8. The biodegradable polyester resin composition according to claim 1, further comprising a copolymerized polyester (C). 9. The copolymerized polyester (C) comprises ethylene glycol and / or 1,4-butanediol as a diol component, terephthalic acid, succinic acid and / or adipic acid as a dicarboxylic acid component, and ε-caprolactone as a lactone component. The biodegradable polyester resin composition according to claim 8, which is a copolymer having a structure obtained by random polycondensation of a diol component, a dicarboxylic acid component, and a lactone component using 10. A film comprising the biodegradable polyester resin composition according to claim 1. 11. The film according to claim 10, which is obtained by T-die molding or inflation molding.