JP2003291209A - Method for manufacturing biodegradable polyester stretched molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a biodegradable polyester stretched molding which can easily manufacture the molding suitable for a packaging material application having biodegradability and excellent heat resistance and transparency. <P>SOLUTION: The method for manufacturing the biodegradable polyester stretched molding for stretching a molten molding while heating the molding the step of: stretching the molten molding at a temperature having a relation of formula (1): Tc-0.40(Tc-Tg)≤Ts≤Tc-0.05(Tc-Tg), wherein Ts(°C) is a heating temperature at the stretching time, Tg(°C) is a glass transition temperature obtained when the molding is measured at a differential scanning heat quantity and Tc(°C) is a cold crystallization temperature. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a stretch-molded body mainly composed of biodegradable polyester. More specifically, the present invention relates to a method for producing a stretch-molded product mainly composed of biodegradable polyester, which has excellent heat resistance and transparency and is suitable for packaging material applications.

[0002]

2. Description of the Related Art The packaging of foods and pharmaceuticals facilitates the work of transporting and distributing the contents,
Maintaining quality is a particularly important role. Therefore, the packaging material is required to have high quality maintenance performance. Specifically, as the ability to protect contents during long-term storage, mechanical strength against external force such as impact and piercing, gas barrier property against oxidative deterioration of contents due to outside air oxygen and deterioration due to moisture evaporation of contents, packaging material Examples of such properties include stability such as oil resistance and heat resistance, which does not denature or deform during storage or use, and hygiene without transfer of harmful substances, off flavors or offensive odors from the packaging material itself. In addition, as a required characteristic of the packaging material, transparency is also an important factor in order to increase the commercial value by the recognizability of the contents and the display effect that encourages the purchaser to purchase.

Conventionally, plastic products have been used for these packaging materials because of their convenience during processing and use. However, in the present consuming society, the usage amount is increasing year by year, and at the same time, the plastic waste problem is becoming more serious year by year. Most plastic wastes are disposed of by incineration or landfill, but in recent years, from the viewpoint of environmental protection, material recycling has been proposed for use as a raw material for plastic products again.

However, as described above, the performance required as a packaging material for plastic products is diverse, and it is not possible to satisfy all of these requirements with a single type of plastic alone. For example, multiple layers are used to form gas barrier films and molding containers. Generally, several kinds of plastics are used in combination. Such a packaging material is very difficult to separate into various resins, and material recycling is impossible in consideration of cost and the like.

On the other hand, for example, Japanese Patent Laid-Open No. 10-601
No. 36 discloses that the melting point is 150 ° C. or higher and the heat of fusion ΔHm is
20 J / g or more, density of non-oriented crystallized product is 1.50 g /
cm ³Heat containing a specific polyglycolic acid
Melt plastic resin material in the temperature range from melting point to 255 ° C
Shaped and less in the temperature range of glass transition temperature to crystallization temperature
Uniaxially oriented polyglycolic acid oriented film
However, it exhibits soil disintegration and has excellent toughness and barrier properties.
It is disclosed that it can be used as a packaging material.

However, the above-mentioned Japanese Unexamined Patent Publication No. 10-6013.
In the example of Japanese Patent Laid-Open No. 5-4, 42-4 near the glass transition temperature is used.
It is stretched at 4 ° C. The oriented film obtained by stretching at such a relatively low temperature may have relatively low crystallization, and in order to develop the film physical properties such as heat resistance, the heat treatment after stretching is relatively high. Since it has to be carried out at a temperature, there is a problem that the transparency of the oriented film is likely to deteriorate.

[0007]

An object of the present invention is to easily produce a biodegradable polyester stretched molded article which is biodegradable and has excellent heat resistance and transparency and which is suitable for use as a packaging material. It is an object of the present invention to provide a method for producing the molded article, which is capable of

[0008]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventor has found that a melt-formed product mainly composed of biodegradable polyester has a specific temperature range in which it has an appropriate crystallization rate. The present invention found that a stretchable biodegradable polyester having biodegradability, heat resistance, and transparency, which is suitable for a packaging material application, can be easily produced by stretching while heating. Reached

That is, the present invention is as follows: In the method for producing a biodegradable polyester stretched molded product in which a melted molded product is stretched in at least uniaxial direction while being heated, a heating temperature Ts (° C) at the time of stretching is a heating rate of 10 ° C / min using the melted molded product as a test piece. The glass transition temperature Tg (° C.) and the cold crystallization temperature Tc (° C.) required for differential scanning calorimetry (according to JIS K7121) according to the above formula (1) are drawn. A method for producing a stretched biodegradable polyester, which is represented by the formula (1) Tc-0.40 (Tc-Tg) ≤Ts≤Tc-.
0.05 (Tc-Tg) 2. 2. The method for producing a stretched biodegradable polyester according to the above 1, wherein the biodegradable polyester is an aliphatic hydroxycarboxylic acid polymer. The method for producing a stretched and molded biodegradable polyester according to the above 1 or 2, wherein the biodegradable polyester is a glycolic acid polymer.

The method for producing the stretched biodegradable polyester of the present invention will be described in detail below. The method for producing a stretched molded article of the biodegradable polyester of the present invention includes a heating temperature Ts during stretching of a melt-molded article mainly composed of biodegradable polyester, a glass transition temperature Tg determined by differential scanning calorimetry, and a cold crystal. It is characterized in that it is in a specific range with respect to the crystallization temperature Tc. According to the present method, the melt-molded product is stretched in a situation where it can be crystallized at an appropriate crystallization rate, so that it is excessively crystallized during the stretching. Can be easily stretched to a desired stretch ratio without breaking. Further, the obtained biodegradable polyester stretched molded article is excellent in transparency without whitening and is also crystallized appropriately, so that it is also excellent in heat resistance.

The heating temperature Ts in the present invention refers to the temperature of the melt-molded product during stretching. For example, when the melt-molded product is heated by blowing hot air, the melt-molded product is heated to the same temperature as the hot air. Therefore, the hot air temperature is set to the heating temperature Ts. When the melt-molded product is radiantly heated with infrared rays, the temperature of the melt-molded product is the heating temperature T.
The heating device is set so as to be s. The stretch-molded product in the present invention mainly refers to a stretched film and a stretched sheet. In the present invention, the film and the sheet are distinguished by simply using different names depending on the difference in thickness, and the film and the sheet are collectively referred to as a molded product. The stretch blow-molded article may also be produced by blow-molding the preform, which is a melt-molded article, in a state where the preform can be crystallized at an appropriate crystallization rate.

Generally, in a film forming process of a plastic molded product, in a method for producing a film by uniaxial stretching or biaxial stretching, a melt-molded product has a temperature "below the melting point and above the second-order transition point (which is synonymous with the glass transition temperature)". It is a usual method to carry out stretching while heating to "" (Plastic Film Research Group, Plastic Film-Processing and Application-, p. 63, Gihodo Publishing (1971)). In particular, in the method for producing a polyethylene terephthalate film, which is a type of polyester, "the film formation conditions are 80 to 130 ° C. and 2.0 to 4.0.
Double Stretching "(Plastic Film Research Group, Plastic Film-Processing and Application-, p. 81, Gihodo Publishing (19
71)) is the usual method.

On the other hand, regarding the thermal characteristics of polyethylene terephthalate, the glass transition temperature is 79 ° C. and the cold crystallization temperature is 12.
8 ° C. (Japan Society for Analytical Chemistry, New Edition Handbook for Polymer Analysis, p. 336, Kinokuniya Bookstore (1995)).
Therefore, the film manufacturing method of stretching in the temperature range of the glass transition temperature to the crystallization temperature defined in the above-mentioned JP-A-10-60136 is a temperature range that can be easily inferred from the prior art in the manufacturing method of polyethylene terephthalate film. Can be said to be stretched.

In the present invention, as a result of diligent examination of the heating temperature condition during stretching in the film forming process of a plastic molding, the natural phenomenon of crystallization of plastic is utilized,
Even between the glass transition temperature Tg and the crystallization temperature Tc, by stretching in the temperature range specified in the following formula (1),
It has been found that the crystal structure of the obtained molded body can be controlled. The following formula (1) can be modified and expressed by the following formula (2). Formula (1) Tc-0.40 (Tc-Tg) ≤Ts≤Tc-
0.05 (Tc-Tg) Formula (2) 0.05 ≦ (Tc-Ts) / (Tc-Tg) ≦
0.40 The crystallization in the present invention is in a thermodynamic non-equilibrium state,
This is a crystallization phenomenon that occurs when heating a so-called glass-state melt-molded product, which is a phenomenon conventionally called cold crystallization. The numerical value for grasping the degree of crystallization can be specifically obtained by obtaining the crystallinity, and can be obtained, for example, by the ratio of the heat of crystal fusion of the test piece to the theoretical heat of fusion by a thermal analysis method.

FIG. 1 shows that the crystallinity of the test piece changes with time.
It is an experimental figure which shows that it changes with heating temperature. In the figure, the horizontal axis indicates the heating time (minutes) and the vertical axis indicates the crystallinity (%). The circle (○) indicates the heating temperature of 50 ° C, and the square (□) indicates the heating temperature of 80 ° C. In each case, the triangle mark (Δ) indicates the case where the heating temperature is 100 ° C., respectively. On the other hand, the glass transition temperature Tg (° C.) and the cold crystallization temperature Tc (° C.) required when the test piece used in this experiment was subjected to differential scanning calorimetry (JIS K7121 compliant) at a heating rate of 10 ° C./min.
Have a glass transition temperature Tg of 11 ° C. and a cold crystallization temperature T
c was 103 ° C. The heating temperature in FIG.
Substituting as Ts of (Tc-Ts) / (Tc-T
The values of g) are 0.58 at 50 ° C. for circles (◯), 0.25 at 80 ° C. for squares (□), and 10 for triangles (Δ).
It becomes 0.03 at 0 ° C.

According to FIG. 1, (Tc-T of the above equation (2) is used.
heating temperature 5 with a value of (s) / (Tc-Tg) of 0.58
At 0 ° C., crystallization of the test piece occurs only slightly, but when the heating temperature at which the value is 0.25 is set to 80 ° C., the test piece becomes crystallized moderately, and when the value is 0.03. It can be seen that at a certain heating temperature of 100 ° C., the crystallization becomes higher. The change with time of the crystallinity shown in the figure is an index showing the crystallization rate, and the heating temperature of the square mark (□) in the figure is 80.
It can be seen that at a temperature at which an appropriate crystallization rate as shown in ° C can be obtained, the progress of crystallization can be controlled during stretching, and a stretched molded product can be produced without excessive crystallization.

Therefore, in the method for producing a stretch-molded product of the present invention, the heating temperature Ts (° C.) for stretching the melt-molded product is
A glass transition temperature Tg (° C.) and a cold crystallization temperature T, which are required when a differential scanning calorimetry (according to JIS K7121) is performed at a heating rate of 10 ° C./min as a test piece using the melt-formed product.
It is specified in the temperature range having the relationship of c (° C.) and the formula (1). Formula (1) Tc-0.40 (Tc-Tg) ≤Ts≤Tc-
0.05 (Tc-Tg) When the value of Ts is higher than (Tc-0.05 (Tc-Tg)) ° C., the crystallization rate of the melt-molded product to be used becomes very high, and therefore, during stretching. In that case, a very high degree of crystallization occurs and the molded product does not reach the desired stretching ratio and breaks, making the manufacturing process of the molded product very complicated, and even if it does not break, it is whitened by the heating operation during stretching and the transparency is extremely high. In some cases, only molded products that are inferior in quality are obtained. On the other hand, the value of Ts is (Tc-0.40
When the temperature is lower than (Tc-Tg)) ° C., the crystallization rate of the melt-molded product to be used is very slow, so that the crystallization does not proceed sufficiently during the stretching, and the molded product that is not heat-set after the stretching has a crystallinity degree. The heat resistance is low and inferior, or the molded product heat-fixed after stretching is whitened and the transparency is extremely inferior. Therefore, the value of Ts is selected from the temperature range having the relationship of the above formula (1), but it has both higher heat resistance and higher transparency, and is more easily stretched without breaking during stretching. In order to produce a molded body, it is preferable to select from a temperature range having the relationship of the following formula (3). Formula (3) Tc-0.30 (Tc-Tg) ≤Ts≤Tc-
0.10 (Tc-Tg)

When the melt-molded product used in the present invention has a plurality of glass transition temperatures or cold crystallization temperatures in the differential scanning calorimetry, for example, at least two or more of the raw materials described below are melt-mixed. In the case of a melt-molded product composed of the composition, the melt-molded product is used as a test piece at a heating rate of 10 ° C./min for differential scanning calorimetry (JIS K712).
2), the glass transition temperature Tg (° C.) of the biodegradable polyester and the cold crystallization temperature Tc (° C.) of which the heat of cold crystallization required is larger, and the heating temperature T during stretching is adopted.
Set s (° C). In the case of a multilayer melt-molded product made of the raw materials described below, the melt-molded product is used as a test piece at a heating rate of 10 ° C./min for differential scanning calorimetry (JIS K71).
21), the glass transition temperature Tg (° C.) and the cold crystallization temperature Tc (° C.) of the biodegradable polyester layer having a higher melting point, which are required to be applied, are adopted, and the heating temperature Ts during stretching is adopted.
Set (℃).

Next, the melt-formed product used in the method for producing a stretch-formed product of the present invention will be described in detail. The melt-molded product contains a raw material mainly composed of biodegradable polyester,
For example, a sheet-shaped material or a tube-shaped material that is melt-molded by a conventionally known general method such as a melt extrusion method, a calender method, and a melt press molding method is not particularly limited. Examples of the biodegradable polyester used in the present invention which is a raw material for the melt-molded product include glycolic acid, 2-hydroxy-containing lactic acid and 2-hydroxyisobutyric acid.
2,2-Dialkyl acetic acids, 3-hydroxybutyric acid, 3-
Direct dehydration polycondensation using aliphatic hydroxycarboxylic acids including hydroxyvaleric acid, 3-hydroxyhexanoic acid, 4-hydroxybutanoic acid and the like, and other known hydroxycarboxylic acid monomers, such as methyl glycolate Dealcoholization polycondensation using ester derivatives of these hydroxycarboxylic acids, or the same or different cyclic dimers of these hydroxycarboxylic acids,
For example, ring-opening polymerization using glycolide (1,4-dioxa-2,5-dione), lactide (3,6-dimethyl-1,4-dioxa-2,5-dione), β-butyrolactone, β -Propiolactone, pivalolactone,
γ-butyrolactone, δ-valerolactone, β-methyl-δ-valerolactone, homopolymer obtained by ring-opening polymerization using a lactone monomer including ε-caprolactone, etc., or optionally from these Polyhydroxycarboxylic acids, polylactones, which are copolymers obtained from two or more selected types, and poly (hydroxycarboxylic acid-co-lactone), which is a copolymer of these hydroxycarboxylic acids or their cyclic dimers and lactones. ), An equimolar amount of polyhydric alcohols and polyhydric carboxylic acids, and examples of polyhydric alcohols include ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-butanediol, and 1-butanediol. , 4-butanediol, 1,5-pentanediol, 2,2-dimethyl-
1,3-propanediol, 1,6-hexanediol, 1,3-cyclohexanol, 1,4-cyclohexanol, 1,3-cyclohexanedimethanol, 1,
Aliphatic diols such as 4-cyclohexanedimethanol, or a combination of a plurality of these aliphatic diols, such as diethylene glycol, triethylene glycol, tetraethylene glycol, and polyvalent carboxylic acids such as malonic acid, succinic acid, glutaric acid, 2,2-
Fats such as dimethyl glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and diglycolic acid Aromatic dicarboxylic acids such as group dicarboxylic acids, terephthalic acid, isophthalic acid, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, these aliphatic dicarboxylic acids and ester derivatives of aromatic dicarboxylic acids, and these aliphatic dicarboxylic acids Polyhydric alcohols and polycarboxylic acids obtained from acid anhydrides and the like are each a homopolymer, or one of polyhydric alcohols and polycarboxylic acids is one type and the other is arbitrarily selected. Copolymers obtained from two or more of the above, or polyhydric alcohols and polycarboxylic acids Aliphatic polyesters each being a copolymer obtained from two or more kinds arbitrarily selected, a combination of the above-mentioned hydroxycarboxylic acids and the like and polyhydric alcohols, such as 1,4-dioxa-2-one Poly (ester-ether) obtained by ring-opening polymerization using a cyclic compound having an ester and ether unit containing
And polyesters obtained by combining the above-mentioned hydroxycarboxylic acids and the like, polyhydric alcohols and polyhydric carboxylic acids.

When these biodegradable polyesters are copolymers, their arrangement is not particularly limited,
Random copolymer, alternating copolymer, block copolymer,
Any of graft copolymers and the like may be used, and the copolymerization composition ratio is not particularly limited, and it is a copolymer in which two or more kinds of constituent monomers are copolymerized at an arbitrary ratio.
Furthermore, when the above-mentioned monomer or the like is an optically active substance, it may be either L-form or D-form, and D-form
Composition of D-body and L-body in any mixing ratio
The copolymerization ratio of the-form may be any copolymer or meso form.

Further, as the biodegradable polyester used in the present invention, in addition to the above-mentioned chemically synthesized polyester, poly (3-hydroxybutyrate), poly (3-hydroxybutyrate-co-3-hydroxyvalerate) is used. , Poly (3-hydroxybutyrate-co-4-hydroxybutyrate), other homopolymers or copolymers of hydroxyalkanoic acid having less than about 12 carbon atoms as monomer units, synthesized by microorganisms Microbial produced polyesters may be used.

The biodegradable polyester used in the present invention is
In order to impart heat resistance to the molded product used as a packaging material, differential scanning calorimetry (JIS
The melting point required in accordance with K7121 is 140 ° C. or higher and 210 ° C. or lower, more preferably 160 ° C. or higher and 205 ° C. or lower, and most preferably 175 ° C. or higher and 200 ° C. or lower. It is desirable that the obtained crystallinity is 10% or more and 70% or less as a test piece that has been sufficiently annealed to be in an equilibrium state (specified in the section of the physical property measurement method described later). It is preferably 15% or more and 60% or less, and most preferably 2
It is 0% or more and 50% or less. Further, in order to impart mechanical strength to the external force required as a packaging material to the molded body,
Alternatively, in order to obtain a melt-molded product with high thickness accuracy and more easily, the molecular weight is preferably 8 × 10 ⁴ or more, more preferably 1 × 10 ⁵ or more in terms of weight average molecular weight. The upper limit of the molecular weight is not particularly limited as long as the melt fluidity can be adjusted by adding a plasticizer or the like, but it is preferably 8 × 10 ⁵ or less in terms of weight average molecular weight.

Among the above-exemplified biodegradable polyesters used in the present invention, a more preferable biodegradable polyester is an aliphatic hydroxycarboxylic acid type polymer, and above all, it imparts heat resistance to a molded product used as a packaging material. Therefore, a glycolic acid-based polymer having a relatively high melting point and an excellent gas barrier property is the most preferable biodegradable polyester. The glycolic acid-based polymer means a polymer whose main monomer unit is glycolic acid, and is glycolide (1,4-dioxa-2, which is a cyclic dimer of glycolic acid.
A polymer obtained by ring-opening polymerization using (5-dione), direct dehydration polycondensation using glycolic acid, polycondensation while dealcoholating using glycolic acid esters such as methyl glycolate. is there.

The polymer is produced by a conventional method known in the art. For example, in order to obtain a glycolic acid-based polymer by ring-opening polymerization using glycolide as a main monomer, Gi is used.
Lding et al. (Polymer, vol. 20,
December (1979)) and the like,
It is not limited to this. In order to make it easier to control the degree of crystallization, it is desirable that the monomer unit is a copolymer of glycolic acid and other than glycolic acid, such as lactic acid. As the glycolic acid-lactic acid copolymer obtained by ring-opening polymerization, the glycolic acid component ratio is 78 to 90 mol% and the lactic acid component ratio is 22 to 10 mol%.
The melting point is 175 to 205 [deg.] C., and the crystallinity determined by the thermal analysis method is a test piece that is sufficiently annealed to be in an equilibrium state and is 15 to 40%. However, in the calculation of the crystallinity by the thermal analysis method, the theoretical heat of fusion uses 207 J / g which is the value of the glycolic acid homopolymer (CC Ch.
u, J. Appl. Poly. Sci. , Vol. Two
6, p. 1726 (1981), J. Brandru
p, et al. , POLYMER HANDBOO
K, 3rd ed. , John Wiley & So
ns (1989)).

The melt-molded product used in the present invention is mainly composed of the above-mentioned biodegradable polyester as a raw material.
That is, it is contained in an amount of 50 wt% or more, and the polyester may be used alone, or may be used in a mixed composition in which two or more kinds are selected from the polyester and melt-mixed at an arbitrary mixing ratio. Further, it may be used as a mixed composition with another polymer as long as it does not impair the biodegradability of the obtained stretched and molded product. The other polymer that can be used as a part of the raw material is a known biodegradable plastic other than the above biodegradable polyester, for example, a natural polymer such as a starch-based or cellulose-based polymer, a polyaspartic acid-based polymer, or the like. Amino acids,
Cellulose esters such as cellulose acetate, aliphatic polyester carbonates, polyvinyl alcohols,
Examples thereof include polyethers such as polyethylene oxide, low molecular weight polyethylene, polymalic acid and the like.

Further, as long as the biodegradability of the obtained stretched molded article is not impaired, for example, polyolefins, aromatic polyesters, polyamides, ethylene-vinyl alcohol copolymers, petroleum resins and terpenes. Resins, hydrogenated products thereof, and other known thermoplastic resins may be mixed. The melt-molded product used in the present invention, if necessary, an additive comprising an inorganic and / or organic compound as a part of its raw material, for example, a plasticizer, a lubricant, an antistatic agent, an antifogging agent, an antioxidant, A heat stabilizer, a light stabilizer, an ultraviolet absorber, a coloring agent, a flame retardant, a crystal nucleating agent and the like may be appropriately mixed.

Specific examples of the plasticizer used include phthalates such as dioctyl phthalate and diethyl phthalate, fatty acid esters such as ethyl laurate, butyl oleate and octyl linoleate, dioctyl adipate and dibutyl sebacate. Aliphatic dibasic acid esters such as, tributyl acetylcitrate and triethyl acetylcitrate such as triethyl, glycerin diacetate laurate and glycerin fatty acid esters such as glycerin triacetate, diglycerin tetraacetate and tetra Polyglycerin fatty acid esters such as glycerin hexaacetate, phosphate esters such as dioctyl phosphate, modified vegetable oils such as epoxidized soybean oil and epoxidized linseed oil, and polybutylene sebacate Of it can be mentioned a polyester-based plasticizers, safety and health of the viewpoint from glycerol fatty acid esters and aliphatic tribasic acid esters are particularly desirable. The melt-molded product is composed of a composition in which one kind or two or more kinds are selected from these and the addition amount is less than 40 wt% in the raw material of the melt-molded product.

Examples of the antioxidant to be used include phenol type, phenyl acrylate type, phosphorus type and sulfur type. The melt-molded product is composed of a composition in which one kind or two or more kinds are selected from these and the addition amount is less than 10% by weight in the raw material of the melt-molded product. When the composition of the biodegradable polyester used in the present invention and the other polymer or the additive is used, all or a part thereof is a single-screw or twin-screw extruder, a Banbury mixer, and a mixing. It is desirable to use a roll, a kneader or the like for melt mixing.

Next, the stretch-molded article obtained by the present invention will be described. The molded body is a molded body that can be stretched by setting the heating temperature in the above-mentioned specific range when the molten molded article is stretched at least uniaxially while being heated. The method for producing the melt-formed product and the method for stretching the melt-formed product are not particularly limited, and a conventionally known general method is used. Examples of the method for producing a melt-molded product include the above-described melt extrusion method, calender method, and melt press molding method,
Specifically, for example, in the melt extrusion method, the above raw materials,
It is dried to a moisture content of 200 wtppm or less in advance, then supplied to an extruder, extruded from a die connected to the tip of the extruder while being heated and melted, and then cooled and solidified to form a sheet or tube. It can be produced as a melt-molded product. Further, in the melt press molding method, the above-mentioned raw materials have a water content of 200 wt in advance.
After drying until it is below ppm, supply it to the mold,
A sheet-like melt-molded product can be produced by heating and melting under normal pressure or reduced pressure atmosphere, pressing, and then cooling and solidifying. In these methods, the melting of the raw materials by heating is usually (melting point −5 ° C.) to (melting point +65).
The temperature is appropriately selected from the temperature range of (° C.).
The cooling and solidification is usually carried out under the conditions of cooling to below the crystallization temperature within 3 minutes to solidify, and preferably under the conditions of rapidly cooling below the glass transition temperature within 2 seconds to solidify into an amorphous state.

As the subsequent stretching method, for example, in the case of uniaxial stretching, the sheet-shaped melt-molded product melt-extruded from a T-die by a melt-extrusion method and cooled by a cast roll is uniaxially lengthwise in the sheet flow direction by a roll stretching machine. Stretching, or a method of producing by laterally uniaxially stretching with a tenter while suppressing the longitudinal stretching ratio as much as possible, or in the case of biaxial stretching, melt extrusion from a T die by melt extrusion method and sheet-shaped melt molding cooled with a cast roll The product is first subjected to longitudinal stretching with a roll stretching machine and then sequentially biaxially stretched with a tenter, or a method for producing by simultaneous biaxial stretching with stretching in both longitudinal and lateral directions with a tenter, melt extrusion from a circular die by a melt extrusion method, There is a method in which a tubular melt-molded product cooled with a water-cooled ring or the like is tubularly stretched to produce. In these cases, the stretching operation is carried out by appropriately selecting the heating temperature during stretching from the above-mentioned specific temperature range, the stretching rate from 10 to 50000% / min, and the stretching ratio from at least one axial direction to the area ratio of 2 to 50 times. It is performed under the conditions. When the heating temperature during stretching is set in multiple stages by the tenter stretching method or the tubular stretching method,
The heating temperature from the portion where the strain change starts at the time of stretching to the portion where the strain change rate is the largest is the heating temperature Ts in the present invention.

The stretch-molded body thus obtained is a soft-to-medium stretch-molded body, in which a relatively large amount of a plasticizer is added and a tensile modulus is less than 4.0 GPa. It is suitable for use as a packaging material such as stretch packaging, casings, and household wraps. When using for shrink wrapping applications such as wrapping while heat shrinking,
It may be used as it is, or may be subjected to heat treatment or aging treatment for the purpose of adjusting the degree of heat shrinkage. or,
When used for a packaging material that is heated in a microwave oven or the like and is required to have heat resistance, it is desirable to perform a heat treatment for the purpose of preventing deformation and melt perforation due to heat from the heat-generated contents.
Further, for the purpose of improving dimensional stability with time and physical property stability, it is desirable to perform aging treatment or the like. The heat treatment is preferably carried out at a temperature appropriately selected from the temperature range of usually 60 to 160 ° C. for 1 second to 3 hours, and the aging treatment is usually carried out at a temperature appropriately selected from the temperature range of 25 to 60 ° C. for 3 hours. It is desirable to be performed for about 10 days.

The stretch-molded product thus obtained may be used as it is as a packaging material for household wraps or the like, but if necessary, coating or corona treatment may be carried out for the purpose of improving the antistatic agent or antifogging property. May be subjected to various surface treatments, or for the purpose of improving sealability, moisture resistance, gas barrier property, printability, etc., laminating or coating, or vacuum deposition of aluminum or the like may be performed. Further, it may be formed into a shape suitable for the intended use by secondary processing. Secondary processed products include, for example, in the case of stretched films, seal processed products such as pillow packaging applications and weld type casing packaging applications, and in the case of stretched sheets, plug assist molding method, air cushion molding method, etc. Vacuum forming, pressure forming,
There are containers such as trays and cups that have been subjected to male-female molding and the like, or blister packaging sheets.

The thickness of the molded article in the present invention is appropriately selected depending on its use as a packaging material, and is usually about 0.5 to 100 μm for a stretched film and 0.1 to about a stretched sheet.
It is about 2 mm, but is not particularly limited. Considering the ease of manufacturing the stretched film and the stretched sheet, it is preferable that the stretched film be manufactured by the tubular stretching method and the stretched sheet be manufactured by the tenter stretching method. However, the distinction between the film and the sheet is simply using different names depending on the difference in thickness, and the heat-resistant and transparent biodegradable polyester stretch-molded article which is the subject of the present invention can be easily prepared. There is no difference in that it can be manufactured. Therefore, in the examples described below, the present invention was described in detail by measuring and evaluating the physical properties of a stretched film having a thickness of about 30 μm.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to Examples. However, these specific examples do not limit the scope of the present invention. In addition, physical property measuring methods, evaluation methods and scales are shown below, but unless otherwise specified, the sample is 1 to 2 in an atmosphere of temperature (23 ± 2) ° C. and relative humidity (50 ± 5)% after the measurement sample is prepared. Those stored for a day were subjected to physical property measurement and evaluation.

[Physical property measuring method] (1) Differential scanning calorimetry of melt-formed product Glass transition temperature Tg (° C) of melt-formed product used for stretching
And the cold crystallization temperature Tc (° C.) were measured by using a DSC6200 manufactured by Seiko Instruments Inc.
It measured based on 1. A sample melt-molded product was used as a test piece, and a test piece weight of 7.5 mg was weighed and firstly measured at -30 ° C.
After being held for 3 minutes, it was heated to 270 ° C. at a heating rate of 10 ° C./minute. The glass transition temperature Tg (° C.) in the differential scanning calorimetric curve in the first heating process and the cold crystallization temperature Tc (° C.) as the crystallization peak temperature were determined. The temperature and the amount of heat were calibrated using indium as a standard substance.

(2) Differential Scanning Calorimetry of Biodegradable Polyester The melting point Tm (° C.) representing the characteristics of the biodegradable polyester is
A sample sheet-like material that had been sufficiently annealed under the following conditions and was in an equilibrium state was used as a test piece, and was determined as a melting peak temperature in a differential scanning calorimetric curve obtained in the same manner as in the differential scanning calorimetric measurement. Also, the crystallinity Xc (%), which represents the characteristics of biodegradable polyester, is
Crystal fusion heat ΔHm measured according to IS K7122
The ratio of (J / g) to the theoretical heat of fusion ΔHf (J / g) was calculated by the following equation (4). Crystal fusion heat ΔHm
(J / g) was determined as the heat of fusion in the differential scanning calorimetric curve obtained in the same manner as in the differential scanning calorimetric measurement, using the sample used for the melting point measurement as a test piece. The theoretical heat of fusion ΔHf (J / g) was quoted from the above-mentioned documents such as POLYMERHANDBOOK as a homopolymer of the main monomer units constituting the sample biodegradable polyester. Note that the fully annealed equilibrium state means that the sheet material before annealing is annealed in a hot air circulation thermostatic bath set to the cold crystallization temperature required when performing differential scanning calorimetry as a test piece. It refers to the state of annealing when the change in crystallinity at intervals of 60 minutes is less than 0.5%. Formula (4) Xc = ΔHm / ΔHf × 100

(3) Differential scanning calorimetric measurement of mixed composition A melt-molded product comprising a composition obtained by melt-mixing two or more kinds of biodegradable polyesters, wherein the differential scanning calorimetric curve of the melt-molded product is used. When there are a plurality of baseline step changes due to the glass transition and / or when there are a plurality of exothermic peaks due to cold crystallization, the above-mentioned differential scanning calorimetry is performed using the melt-molded product as a test piece. The glass transition temperature Tg (° C.) and the cold crystallization temperature Tc (° C.) of the biodegradable polyester having the larger cold crystallization heat ΔHc (J / g) required when measured in the same manner as in (JIS K7122) To adopt.

(4) Differential scanning calorimetry of multi-layered product A multi-layered melt-molded product, wherein the differential scanning calorimetric curve of the melt-molded product has a plurality of stepwise changes in the baseline due to glass transition. And / or when there are a plurality of exothermic peaks due to cold crystallization, the melting point obtained when the melt-molded product is used as a test piece in the same manner as in the differential scanning calorimetry (JIS K7121). The glass transition temperature Tg (° C) of the biodegradable polyester having a higher Tm (° C) and the cold crystallization temperature Tc (° C) are adopted. The melting point Tm (° C.) was determined as a melting peak temperature in a differential scanning calorimetric curve obtained in the same manner as in the differential scanning calorimetric measurement using the melt molded product as a test piece.

[Evaluation Method and Scale] (1) Transparency Transparency was evaluated by measuring haze using a stretched molded body as a sample. The haze is measured by using a haze meter HR-100 manufactured by Murakami Color Research Laboratory Co., Ltd.
7105 was measured. A stretch-molded body sample having a thickness of about 30 μm was cut into a square having a side of 50 mm, which was set in a holder and the haze of the sample was measured.
The haze measurement results were obtained by measuring 5 samples each and showing the average value. This haze was used as an index of transparency.

[0040] <Evaluation scale> Haze judgment remarks Less than 2% ◎ Transparent and very excellent in visibility 2% or more and less than 5% ○ Excellent visibility with a slight whitening 5% or more and less than 10% △ Whitening and poor visibility 10% or more × Remarkably whitening and very poor visibility

(2) Heat resistance The heat resistance was evaluated by carrying out a load bearing cutting test using a stretched molded body as a sample. The load-bearing cutting test is carried out by heating the strip-shaped test piece under a load of 30 g for 1 hour in a hot-air circulation thermostat set to a constant temperature, and checking whether or not the test piece is cut.
The maximum temperature at which the test piece did not cut was measured. Thickness about 30μ
The stretched molded product of m was cut into a strip shape having a length of 140 mm and a width of 30 mm. Fixing jigs and load jigs were attached to the upper and lower ends of the strip-shaped test pieces of 25 mm each, and the test pieces were heated for 1 hour in a hot-air circulating thermostat set to a constant temperature to check whether or not the test pieces were cut. When the strip-shaped test piece was not cut, the set temperature was increased by 5 ° C. with a new test piece, and the above procedure was repeated. The measurement result of the maximum temperature at which the strip-shaped test piece was not cut was shown as the mode value by performing this test 5 times for each stretch-molded body.

[0042] <Evaluation scale> Load-bearing cutting test Judgment Remarks 180 ° C or higher ◎ Extremely high heat resistance and no problem in practical use 160-175 ° C ○ High heat resistance and can be used depending on the application 140-155 ° C △ Poor heat resistance and limited applications 135 ° C or less × Heat resistance is extremely low and cannot be put to practical use

[0043]

Example 1 [Purification of monomer] Glycolide (1 kg) was dissolved in ethyl acetate (3 kg) at 75 ° C, and the mixture was allowed to stand at room temperature for 48 hours.
It was left to stand for a time to cause precipitation. The precipitate collected by filtration is about 3 at room temperature.
Washing was performed with kg of ethyl acetate. After repeating this washing operation again, the washed product is put in a vacuum dryer and
Vacuum drying was performed at 24 ° C. for 24 hours. This dried product was depressurized to 6 to 7 mmHg under a nitrogen atmosphere and subjected to simple distillation to 133 to 1
As a distillate at 34 ° C., 480 g of distilled and purified glycolide was obtained. 1 kg of L-lactide was dissolved in 3 kg of toluene at 80 ° C., and then left standing at room temperature for 48 hours for precipitation.
The precipitate collected by filtration was washed at room temperature with about 3 kg of toluene. After repeating this washing operation again, the washed product was placed in a vacuum dryer and vacuum dried at 60 ° C. for 24 hours to obtain 560 g of purified L-lactide.

[Preparation of Polymer] 420 g of glycolide and 250 g of lactide obtained by purifying the above monomers, 0.2 g of tin 2-ethylhexanoate and 0.05 g of lauryl alcohol as a catalyst were glass-lined on the inner surface. Charge the reactor with a jacket and blow it with nitrogen to about 1
Dried at room temperature for hours. Then, while blowing nitrogen, 1
The temperature was raised to 30 ° C. and the mixture was stirred for 40 hours to carry out polymerization. After the completion of the polymerization operation, cooling water is passed through the jacket to cool it,
The lump polymer taken out from the reactor was crushed to about 3
It was crushed into fine particles of mm or less. The pulverized product was subjected to Soxhlet extraction with tetrahydrofuran for 60 hours, dissolved in 3 kg of hexafluoroisopropanol at 50 ° C., and then reprecipitated with 7 kg of methanol. This reprecipitate was vacuum dried in a vacuum dryer set at 130 ° C. for 60 hours to give 520 g of glycolic acid-lactic acid copolymer.
Got

70 mg of the obtained copolymer was obtained.
Was dissolved in ¹ ml of trifluoroacetic acid-D and ¹ H-NMR
When the copolymerization component ratio was analyzed by, the glycolic acid component ratio was 81 mol% and the lactic acid component ratio was 19 mo.
It was 1%. The amount of residual monomers of glycolide and lactide, which are the monomers, was 340 wt in total when the remaining monomers were quantified by gas chromatography as a 0.5% by weight hexafluoroisopropanol solution of the copolymer.
It was ppm. 80 mg of the copolymer 20 mg
Was dissolved in 3 g of hexafluoroisopropanol containing sodium trifluoroacetate, and the molecular weight was measured by GPC. The weight average molecular weight in terms of polymethylmethacrylate was 2 × 10 ⁵ .

The obtained copolymer was left for about 2 hours in a hot air circulating constant temperature bath set at 130 ° C. for drying operation, and then heated and pressed for 5 minutes by a heating press set at 230 ° C., Then, it was cooled with a cooling press set to 20 ° C. to obtain a sheet-like material having a thickness of 200 μm. According to the above-mentioned differential scanning calorimetric measuring method of biodegradable polyester, the sheet-shaped material was subjected to a differential scanning calorimetric measurement before the annealing treatment. The cold crystallization temperature was 131 ° C. and the cold crystallization heat was 15 J.
/ G, the melting point was 188 ° C, and the heat of fusion of crystal was 15 J / g. After that, when the sheet-shaped material was annealed at 131 ° C. and the differential scanning calorimetry was performed, the change in crystallinity at a processing time of 120 minutes and a processing time of 180 minutes was less than 0.5%. The melting point Tm of the copolymer obtained from the differential scanning calorimetric curve at 120 minutes was 188 ° C., and the crystallinity Xc was 19%. The crystallinity Xc was calculated with the theoretical heat of fusion ΔHf being 207 J / g.

[Preparation of Melt-Formed Sheet] The copolymer obtained in the above-mentioned preparation of the polymer was allowed to stand for about 2 hours in a hot-air circulation thermostat set at 130 ° C., and dried. The amount of water measured by a Karl Fischer moisture meter equipped with a water vaporizer at 240 ° C. was 158 wtppm. The dried copolymer was supplied under a nitrogen stream to an extruder equipped with a liquid injection pump and equipped with a strand die at the tip, and triacetin as a plasticizer was added from the liquid injection pump so that the added amount was 20 wt%. The copolymer was added, and the copolymer and triacetin were melt-mixed at 230 ° C. and extruded from a strand die for granulation. The granulated composition was left to stand in a hot air circulation thermostat set at 130 ° C. for about 2 hours again to perform a drying operation, and then heated and pressed for 5 minutes by a heating press set at 230 ° C., and then at 25 ° C. It was cooled with a cooling press set to ℃ to obtain a sheet-like melt-molded product having a thickness of 350 μm. When the differential scanning calorimetry was performed on the melt-formed product as a sample according to the differential scanning calorimetry method of the above-mentioned melt-formed product, the glass transition temperature Tg of the melt-formed product was 11 ° C and the cold crystallization temperature Tc was 103 ° C. Met.

[Preparation and Evaluation of Stretched Molded Product] Stretching of the melt-molded product obtained in the above-mentioned preparation of the sheet-shaped melt-molded product
It was performed using a biaxial stretching test device manufactured by Toyo Seiki. The melt-molded product was cut into a square having a side of 90 mm, mounted in a chamber having a heating temperature of 80 ° C. at the time of stretching and a clamp having a distance between the clamps of 80 mm, and a longitudinal speed of 3.5 times at a stretching speed of 50% / min. Simultaneous biaxial stretching was performed up to 3.5 times in width.
Immediately after completion of the stretching operation, cold air was blown to cool the stretched molded body. The obtained stretch-molded body was fixed to a metal frame and heat-treated for 30 seconds in a hot air circulating constant temperature bath set at 90 ° C. to obtain a stretch-molded body having a thickness of 30 μm. The stretched molded body thus obtained is designated as F1. When the transparency and heat resistance were evaluated using the molded product F1 as a sample, the haze was 1.1% and the maximum temperature at which it was not cut was 180 ° C.
The transparency was ⊚, the heat resistance was ⊚, and the overall judgment was ⊚. From the above evaluation results, it is understood that the obtained molded product F1 has excellent heat resistance and transparency and is suitable for packaging material applications.

[0049]

Examples 2 to 4 and Comparative Examples 1 to 4 Next, the same experiment as in Example 1 was repeated except that the heating temperature at the time of stretching was 95 ° C., and the obtained stretched and molded product was designated as F2. . When the transparency and heat resistance were evaluated using the molded product F2 as a sample, the haze was 2.5% and the maximum temperature at which it was not cut was 180 ° C (Example 2). The same experiment as in Example 1 was repeated except that the copolymer simple substance was used without being melt-mixed with the plasticizer triacetin, and the heating temperature at the time of stretching was 120 ° C. The obtained stretched molded product was designated as F3. . Here, the melt-formed product used for stretching had a glass transition temperature Tg of 34 ° C. and a cold crystallization temperature Tc of 131 ° C. When the above-mentioned transparency and heat resistance were evaluated using the molded product F3 as a sample, the haze was 1.2% and the maximum temperature at which it did not break was 185 ° C (Example 3). The same experiment as in Example 3 was repeated except that the heating temperature at the time of stretching was 100 ° C., and the obtained stretch-molded body was designated as F4. The molded body F
When the above-mentioned transparency and heat resistance were evaluated using Sample No. 4 as a sample, the haze was 1.0%, and the maximum temperature without cutting was 175 ° C. (Example 4). The heating temperature during stretching is 5
The same experiment as in Example 1 was repeated except that the temperature was 0 ° C., and the obtained stretch-molded body was designated as F5. When the above-mentioned transparency and heat resistance were evaluated using the molded product F5 as a sample, the haze was 0.8%, and the maximum temperature at which it was not cut was 10%.
It was 0 ° C. (Comparative Example 1). The heating temperature during stretching is 65 ° C.
The same experiment as in Example 1 was repeated except that the above was performed, and the obtained stretch-molded body was designated as F6. When the transparency and heat resistance were evaluated using the molded product F6 as a sample, the haze was 0.9%, and the maximum temperature at which it was not cut was 140 ° C.
Was (Comparative Example 2). The same experiment as in Example 1 was repeated except that the heating temperature during stretching was 100 ° C., and the obtained stretched and molded product was designated as F7. When the above-mentioned transparency and heat resistance were evaluated using the molded body F7 as a sample,
The haze was 11.5%, and the maximum temperature without cutting was 180 ° C (Comparative Example 3). The same experiment as in Example 3 was repeated except that the heating temperature at the time of stretching was 65 ° C., and the obtained stretched molded product was designated as F8. When the above-mentioned transparency and heat resistance were evaluated using the molded product F8 as a sample, the haze was 0.8% and the maximum temperature at which it was not cut was 120 ° C (Comparative Example 4).

Regarding F1 to 8 of these stretch-molded articles, the measurement results of the differential scanning calorimetry of the melt-molded articles used for stretching,
The heating temperature conditions during stretching and the evaluation results of the transparency and heat resistance of the molded product are summarized in Tables 1 and 2.

[0051]

[Table 1]

[0052]

[Table 2]

According to Table 1, in the method for producing the stretch-molded bodies of Examples 1 to 4 stretched in the temperature range specified by the above-mentioned formula (1), whitening occurs because excessive crystallization does not occur during stretching. Without stretching, it can be stretched to a desired stretching ratio without breaking, and in order to appropriately crystallize it, a stretched molded article having excellent heat resistance can be obtained even if the heat treatment conditions are set more relaxed in the heat treatment performed after stretching. It is understood that the molded body can be easily manufactured. Further, it can be seen that the stretch-formed products F1-4 of Examples 1 to 4 have excellent heat resistance and transparency and are suitable for use as packaging materials. Among them, the stretch-molded articles F1 and F3 of Example 1 and Example 3 stretched in the temperature range specified by the above-mentioned formula (3) are remarkably excellent in both heat resistance and transparency and are suitable for packaging materials. It turns out to be particularly suitable.

On the other hand, according to Table 2, the value of the heating temperature Ts during stretching is (Tc-0.40 (Tc-Tg)) ° C.
Comparative Examples 1-2 and Comparative Example 4 stretched at a lower temperature
Although the method for producing a stretch-molded body of No. 1 can stretch without breaking to a desired stretch ratio without excessive crystallization, the obtained stretch-molded bodies F5 to 6 and F8 have the above-mentioned Examples 1 to 4 after stretching. Even when the heat treatment was performed under the same conditions, the heat resistance was extremely poor. Further, the stretched molded product F7 of Comparative Example 3 stretched at a temperature of the heating temperature Ts during stretching is higher than (Tc-0.05 (Tc-Tg)) ° C., the transparency is remarkably inferior. It turns out that it is not suitable for.

[0055]

Reference Example This experiment is an experiment for investigating that the change with time of the crystallinity of the melt-molded product varies depending on the heating temperature. Therefore, as the melt-molded products, the same raw materials and the same manufacturing method are used, and the other heating conditions except the heating temperature are set to the same conditions for comparison. When the heating temperature of the above-mentioned Example 1 is reproduced in a pseudo manner as the method for producing the stretch-molded article of the present invention, and the value of the heating temperature Ts during stretching is (Tc
When the heating temperature of Comparative Example 1 stretched at a temperature lower than −0.40 (Tc−Tg)) ° C. is simulated, the value of the heating temperature Ts during stretching is (Tc−0.05 (Tc -T
g)) In the case where the heating temperature of Comparative Example 3 stretched at a temperature higher than 0 ° C. was reproduced in a simulated manner, the melt-formed product was
The crystallinity after heating for ˜5 minutes was determined by the differential scanning calorimetry described above and summarized in FIG.

In FIG. 1, the horizontal axis represents the heating time (minutes), the vertical axis represents the crystallinity (%), and the circles (◯) represent the heating temperature of 50.
℃, the square mark (□) is the case of heating temperature 80 ℃,
The triangles (Δ) indicate the cases where the heating temperature is 100 ° C., respectively. On the other hand, the test piece used in this experiment was heated at a heating rate of 10 ° C /
The glass transition temperature Tg (° C.) and the cold crystallization temperature Tc (° C.), which are obtained when the differential scanning calorimetry (according to JIS K7121) is measured in minutes, are 11 respectively.
C., the cold crystallization temperature Tc was 103.degree. Substituting the heating temperature in FIG. 1 as Ts in the above equation (2), (Tc-
The value of Ts) / (Tc-Tg) is 50 (circle).
0.58 at ℃, 0.25 at 80 ℃ marked with a square (□),
It becomes 0.03 at a triangle mark (Δ) at 100 ° C.

According to FIG. 1, (Tc-T of the above equation (2) is used.
heating temperature 5 with a value of (s) / (Tc-Tg) of 0.58
At 0 ° C., crystallization of the test piece occurs only slightly, but when the heating temperature at which the value is 0.25 is set to 80 ° C., the test piece becomes crystallized moderately, and when the value is 0.03. It can be seen that at a certain heating temperature of 100 ° C., the crystallization becomes higher. The change with time of the crystallinity shown in the figure is an index showing the crystallization rate, and the heating temperature of the square mark (□) in the figure is 80.
It can be seen that at a temperature at which an appropriate crystallization rate as shown in ° C can be obtained, the progress of crystallization can be controlled during stretching, and a stretched molded product can be produced without excessive crystallization.

[0058]

EFFECTS OF THE INVENTION According to the present invention, a melt-molded product mainly composed of biodegradable polyester is used, and the melt-molded product is stretched while being heated to a specific temperature range where the melt-molded product has an appropriate crystallization rate. It is possible to easily manufacture a biodegradable polyester stretched molded article that is biodegradable, and has excellent heat resistance and transparency and that is suitable for use as a packaging material.

[Brief description of drawings]

FIG. 1 shows that the change in crystallinity of the melt-molded product over time varies depending on the heating temperature.
It is the graph figure shown in the case of 0 degreeC.

Claims (3)

[Claims] 1. In a method for producing a stretched biodegradable polyester body in which a melt-molded product mainly composed of biodegradable polyester is heated and stretched in at least uniaxial direction, a heating temperature Ts (° C.) during stretching is Differential scanning calorimetry (JIS) at a heating rate of 10 ° C / min.
Glass transition temperature T required when (according to K7121)
A method for producing a stretched biodegradable polyester, which comprises stretching at a temperature having a relationship of g (° C.) and a cold crystallization temperature Tc (° C.) of the following formula (1). Formula (1) Tc-0.40 (Tc-Tg) ≤Ts≤Tc-
0.05 (Tc-Tg) 2. The method for producing a stretched biodegradable polyester according to claim 1, wherein the biodegradable polyester is an aliphatic hydroxycarboxylic acid polymer. 3. The biodegradable polyester is a glycolic acid-based polymer, wherein the biodegradable polyester is a glycolic acid-based polymer.
A method for producing the stretched biodegradable polyester article described.