JP2002053679A - Copolyester oriented film and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copolyester oriented film having biodegradability, excellent in mechanical strengths and resistance to hot water and useful as a food wrapping film or the like. SOLUTION: This copolyester oriented film consists mainly of 45-55 mol% butanediol component, 20-30 mol% terephthalic acid component, 20-30 mol% adipic acid component and 0-5 mol% sulfonate compound component and is characterized by having >=35 Mpa tensile breaking strength, >=180% tensile elongation at break and <=10 deg.C temperature difference between the peak temperature of its main dispersion and the peak temperature of a non-oriented one in dynamic viscoelasticity measurement. A multilayer film is obtained by including the film and a wrapping film and a packaging container are obtained respectively by utilizing the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a stretched copolyester film and its use. More specifically, a stretched aliphatic / aromatic copolyester film which is excellent in biodegradability (disintegration in soil), mechanical strength and hot water resistance, and is useful as a wrap film or a packaging material for various articles such as food. And its uses.

[0002]

2. Description of the Related Art In recent years, as environmental problems have become more serious, there has been an increasing demand for biodegradable, environmentally friendly packaging materials. Since packaging materials for various articles such as foods are required to have high reliability in preserving contents, synthetic resin films having excellent mechanical strength and heat resistance are generally used. However, general-purpose synthetic resin films such as polyolefin-based films, polyamide-based films, and polyvinylidene chloride-based films have been developed for high performance and long-term stability, so they have excellent physical properties such as mechanical strength. After being released into the natural world, it remains intact without any decomposition. Used packaging materials are collected as garbage and incinerated or landfilled. However, in fact, a large amount of scattered garbage has been pointed out, which has a negative effect on natural ecosystems. There are also environmental pollution due to incineration, narrowing of landfills, and problems with location.

On the other hand, a biodegradable polymer is a polymer that is finally decomposed into water and carbon dioxide by the action of microorganisms and does not remain in the environment. The biodegradable polymer includes a polymer whose shape is collapsed by the action of microorganisms in soil or the sea. If such a biodegradable polymer can be used as a raw material to produce a packaging material having physical properties that can be substituted for a general-purpose synthetic resin film, these environmental problems can be reduced.

[0004] However, films used for packaging materials and the like are required to have mechanical properties, thermal properties, melt processability, economy, and the like. Most biodegradable polymers are used as packaging materials. It is difficult to form a film having sufficient physical properties. For example, a film formed using starch has insufficient mechanical strength and heat resistance, and is difficult to melt-process. Films made of cellulose are unsatisfactory in mechanical strength and are difficult to melt-process. A film formed using a microorganism-produced polyester has a problem that the mechanical strength is insufficient and the cost is high. Since polycaprolactone has a low melting point of 60 ° C., it cannot form a film having excellent heat resistance.

[0005] In order to obtain a film having excellent mechanical strength and heat resistance applicable to applications such as packaging materials, it is generally indispensable to arrange a stretching step during film production. Many of them are unsatisfactory in heat resistance, melt processability and stretch orientation, so that it is difficult to form a stretched film having excellent physical properties using simple equipment or existing equipment.

Japanese Patent Publication No. 10-508640 discloses an aromatic and aliphatic copolymer type copolyester having biodegradability, and its application to a biodegradable film has also been proposed. Specifically, a biodegradable film based on terephthalic acid, butanediol, and adipic acid, which is decomposed by an enzyme possessed by a microorganism, is described. But,
This prior art document only discloses a film formed by blow molding, but does not disclose a stretched film.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a stretched aliphatic / aromatic copolyester film having biodegradability, excellent mechanical strength and hot water resistance, and its use. .

[0008]

SUMMARY OF THE INVENTION The present invention relates to the following copolyester stretched film and its use. 1) A stretched copolyester film containing 45 to 55 mol% of a butanediol component, 20 to 30 mol% of a terephthalic acid component, 20 to 30 mol% of an adipic acid component, and 0 to 5 mol% of a sulfonate compound component as main components. The tensile breaking strength is 35 MPa or more, the tensile breaking elongation is 180% or more, the difference between the peak temperature of the main dispersion and the peak temperature of the non-oriented material in dynamic viscoelasticity measurement is 10 ° C. or less, and the degree of crystal orientation is 60
% Or more of the copolyester stretched film. 2) The stretched copolyester film according to the above 1, wherein the hot water resistance is 80 ° C or higher. 3) The oxygen permeability of the film having a thickness of 40 μm at 30 ° C. and 80% RH is 1800 cm ³ / m ² · day · atm.
2. The stretched copolyester film according to the above 1, which is: 4) A multilayer film having at least one layer of the stretched film according to any one of the above items 1 to 3. 5) A packaging container comprising the film described in any one of 1 to 4 above. 6) A wrapping film comprising the film according to any one of 1 to 4 above.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. (1) Copolyester The copolyester used in the present invention contains 45 to 55 mol% of a butanediol component and a terephthalic acid component of 20 to 55 mol%.
It is a copolyester comprising 30 mol%, adipic acid component 20-30 mol%, and sulfonate compound component 0-5 mol%, and has a melting point (Tm) of 85-130 ° C., -10 ° C. or less, preferably -100 to -10 C, more preferably a glass transition temperature (Tg) of -50 to -10C. Examples of the butanediol compound from which the butanediol component is derived include 1,2-butanediol and 1,4-butanediol, with 1,4-butanediol being preferred. Examples of the terephthalic acid compound from which the terephthalic acid component is derived include terephthalic acid or a monoester or diester thereof. The ester is preferably an alkyl ester, for example, a monoester or diester such as methyl, ethyl, butyl, propyl, pentyl and hexyl. Examples of the adipic acid compound from which the adipic acid component is derived include adipic acid, its acid anhydride, its monoester or diester. The ester is preferably an alkyl ester, for example, a monoester or diester such as methyl, ethyl, butyl, propyl, pentyl and hexyl. Examples of the sulfonate compound from which the sulfonate compound component is derived include a dicarboxylic acid having a sulfonate group, its monoester, diester, alkali metal salt, or alkaline earth metal salt. Preferred is an alkali metal salt of 5-sulfoisophthalic acid, and particularly preferred is a sodium salt.

In addition to the above components, a compound component having three or more functional groups capable of forming an ester bond can be included. Specifically, it is a compound having 3 to 10 functional groups, preferably 3 to 6 hydroxyl groups, carboxyl groups and their derivative groups in the molecule. For example, tartaric acid, citric acid, maleic acid, Examples include methylolpropane, trimethylolethane, pentaerythritol, polyethertriol, glycerol, trimesic acid, trimellitic acid or anhydride, pyromellitic acid or dianhydride, hydroxyisophthalic acid, and the like. With this compound component, the melt viscosity of the copolyester can be adjusted, the impact strength can be increased, and the crystallinity can be reduced.

In addition, various additives can be blended as long as the properties of the stretched film of the present invention are not impaired. Specific examples include an inorganic filler for imparting lubricity and blocking resistance, stearic acid, a higher fatty acid amide, an ethylenebisfatty acid amide having 12 to 22 carbon atoms, etc .; a polyglycerol fatty acid ester for imparting antifogging property, Nonionic surfactants such as glycerin fatty acid ester, sorbitan fatty acid ester, and propylene glycol fatty acid ester; phenol-based, sulfur-based, phosphorus-based antioxidants for imparting anti-deterioration properties, benzophenone-based, benzotriazole-based, and salicylic acid Examples include phenyl-based ultraviolet absorbers.

The polymerization for preparing the copolyester can be carried out by a known method (WO92 / 13019; EP-A5685).
93; EP-A565235; EP-A28687, etc.). For example, the above-mentioned butanediol compound, terephthalic acid compound, adipic acid compound, if desired, a sulfonate compound, and other additives are added in the presence of a catalyst in a melt at 160 to 230 ° C. under atmospheric pressure under inert pressure. Polymerization can be performed under a gas atmosphere.

As the catalyst, those commonly used in the production of polyester can be used. For example, Ti, Ge, Zn, F
metal compounds based on e, Mn, Co, Zr, V, Ir, La, Ce, Li or Ca, preferably organometallic compounds based on these metals (eg salts of organic acids, alkoxides, acetylacetonates and the like) ), Particularly preferred are organometallic compounds based on zinc, tin and titanium. When the stretched film of the present invention is used in the field of packaging foodstuffs, it is desirable to select a catalyst having low toxicity and capable of obtaining a sufficient catalytic effect with a small amount of use. For example, titanium compounds and zinc compounds are known as harmless catalysts for the human body, and dibutoxydiacetacetoxytitanium, tetrabutylorthotitanate, zinc (II) acetate and the like can be used as preferred catalysts. The amount of the catalyst to be used is generally 0.01 to 3 parts by mass, preferably 0.05 to 2 parts by mass, per 100 parts by mass of the monomer component. In the case of a highly active titanium compound catalyst, for example, 0.00
It may be about 01 parts by mass.

The copolyester may be blended with another polymer for the purpose of improving physical properties as long as the biodegradability is not impaired. As the polymer to be blended, a polymer having biodegradability itself is preferable. For example, for the purpose of improving heat resistance and hardness, polylactic acid, polyglycolic acid, or the like is mixed with the copolyester 1
0.1 to 50 parts by mass, preferably 10 parts by mass, per 100 parts by mass
４５45 parts by mass can be blended. Alternatively, a natural biodegradable polymer such as starch or cellulose may be blended.

(2) Stretched copolyester film The stretched copolyester film of the present invention is obtained by biaxially stretching the above copolyester. Stretching can be performed by a known biaxial stretching method. Either a simultaneous stretching method in which stretching is performed vertically and horizontally at the same time, or a sequential stretching method in which stretching is performed uniaxially in advance and then further in the perpendicular direction may be performed.
The stretching method may be any of roll stretching, flat stretching and tubular stretching. In order to efficiently and economically produce the copolyester stretched film of the present invention, a tubular simultaneous stretching method represented by an inflation stretching method or a flat sequential stretching method represented by a tenter sequential stretching method is preferred.

When stretching is performed by the inflation stretching method, a known inflation stretching apparatus can be used. The raw material resin is supplied to an extruder, melt-extruded into a tube from a ring die, formed into a cylindrical shape, and a continuous tube-shaped parison is produced. (Such as air or nitrogen gas) and stretched. The stretching temperature may be set in the range from the crystal melting temperature of the copolyester to the crystal melting temperature −50 ° C.

In the case of stretching by a tenter sequential stretching method, an unstretched material (non-oriented sample) extruded and formed into a sheet is stretched in a longitudinal direction (MD) at a predetermined temperature, and the end portion is stretched to a plurality of tenters. It is gripped with a clip and stretched in the width direction (TD) under a predetermined temperature atmosphere, and a known tenter stretching device can be used. The preheating temperature and the stretching temperature may be set in the range from the crystal melting temperature to the crystal melting temperature −50 ° C., and the tensile speed may be set in the range of 0.5 to 10.0 m / min, preferably 1.0 to 5.0 m / min.

In any method, after stretching, if necessary, at a temperature of usually 60 to 110 ° C., preferably 80 to 100 ° C., for 1 second to 3 hours, preferably 3 seconds to 30 minutes.
It can be heat-set under fixed length or under tension.

The stretching ratio is preferably from 2 to 8 times, more preferably from 3 to 7 times in the machine direction (MD), and in the width direction (T).
D) is preferably 2 to 8 times, more preferably 3 to 7 times. If the stretching ratio is too small, the degree of orientation becomes small, and the mechanical strength and heat resistance decrease.

According to the present invention, the tensile strength at break is 35MP.
a, tensile elongation at break of 180% or more, difference between peak temperature of main dispersion and peak temperature of non-oriented material (unstretched film) in dynamic viscoelasticity measurement of 10 ° C. or less, and degree of crystal orientation of 60
% Is obtained.

The difference in the peak temperature of the main dispersion in the dynamic viscoelasticity measurement is a measure of the difference in the degree of orientation of the amorphous molecular chains in the stretched film. If this temperature difference exceeds 10 ° C., the dimensional stability and The tensile elongation at break is undesirably reduced. The temperature difference is preferably from 0.01 to 10 ° C, more preferably from 0.1 to 10 ° C.
The temperature is 6C, particularly preferably 1-5C.

The degree of crystal orientation is a degree of orientation measured when X-rays are incident parallel to the film surface by wide-angle X-ray diffraction, and is a measure of the degree of orientation of the film surface. If the degree of orientation is less than 60%, mechanical strength such as tensile breaking strength may be impaired. The preferred degree of crystal orientation is 70% or more. Such a stretched film has excellent uniformity of plane orientation and low anisotropy of mechanical strength.

The stretched copolyester film of the present invention has a thickness of usually 1 to 500 μm, preferably 3 to 300 μm.
m, more preferably 5 to 200 μm. If the film thickness is too thin, the desired strength cannot be maintained, and if it is too thick, stretching becomes difficult.

The stretched copolyester film of the present invention comprises:
The hot water resistance is 80 ° C. or higher, preferably 90 ° C. or higher, and more preferably 95 ° C. or higher. In addition, the evaluation method of the hot water resistance is as follows.
After leaving for 2 hours, the size is reduced to 100 mm x 100 mm.
After cutting out and superimposing, three sides were impulse-sealed and then tap water was added, and the remaining one side was impulse-sealed to obtain a sample, which was immersed in a specific temperature of 80 ° C. or higher for 30 minutes and taken out. When there was no water leakage or significant deformation, the temperature higher than the specific temperature was regarded as good hot water resistance.
The stretched copolyester film of the present invention has a thickness of 4
The oxygen permeability of the 0 μm film at 30 ° C. and 80% RH is preferably 1800 cm ³ / m ² · day · atm or less.

The stretched copolyester film of the present invention obtained as described above has good biodegradability, and when it is taken out after being buried in soil for a certain period (28 days), a crack is partially formed. Either the chip has lost its original shape due to chipping or the like, or the tensile strength at break has fallen to 50% or less in the value before filling.

Although the stretched copolyester film of the present invention can be used as a single-layer film, it may be formed into a multilayer film by coextrusion or lamination. In the case of a multilayer film, a plurality of the copolyester stretched films may be laminated, or a laminate of the copolyester stretched film and another film may be laminated. As other films, for the purpose of imparting gas (oxygen) barrier properties,
Ethylene-vinyl alcohol copolymer, vinyl chloride-vinylidene chloride copolymer, polyglycolic acid and the like can be used. Among them, since polyglycolic acid itself has biodegradability, it can be used as a biodegradable laminated film. For the purpose of improving strength and heat resistance, a laminated film of polyamide, polyethylene terephthalate, and polyolefin (eg, polypropylene) may be used. The stretched copolyester film of the present invention can also be used as a heat seal layer.

(3) Packaging Use The stretched copolyester film of the present invention or the multilayer film containing at least one layer of the film can be used as a wrapping film and a packaging material (packaging container) for various articles. The form of packaging is not particularly limited,
It can be used for pouches (including standing), skin packs, shrink packs, pillow packs, rocket packs, blister packs, deep draw packs, tray cup packs, potion packs, and strip packs.

There are no particular restrictions on the items to be packaged, such as foods, pharmaceuticals, cosmetics, precision instruments, and home appliances. As a specific example,
Cereals and processed cereals such as flour, rice, rice cake, noodles, instant noodles;
Meat and processed meat, processed meat, prepared meat and processed meat, such as chicken eggs; milk and dairy products such as milk, butter, cheese; fresh food, processed fishery products, processed meat products, processed fish and processed fishery products such as shaved knots; Vegetables, fruits, fruit drinks, vegetables and fruits such as cut vegetables; sweets, bread, candy, chocolate and other sweets and breads; fermented marine products, miso, soy sauce, pickles, sake, wine, and other fermented foods; mayonnaise, dressing, Seasonings such as tomato ketchup, sauce, vinegar, and cooking oil; Japanese tea, coffee, oolong tea, black tea, soft drinks,
Spices and other luxury items; retort foods, frozen foods, boiled tsukudani,
Cooked and processed foods such as delicacies; bento prepared food, cooked bread, sandwiches, konjac, tofu, cooked rice and other daily cooked foods; medical products such as solid preparations, solutions, ointments; cosmetics, powder detergents, toothpastes, shampoos, solid soaps Cosmetics and toiletries, such as disposable diapers and sanitary products; and precision machines and home appliances, such as personal computers, printers, cameras, televisions, and refrigerators.

[0029]

The present invention will be specifically described below with reference to examples and comparative examples. Methods for measuring physical properties and the like are as follows.

(1) Main dispersion peak temperature The sample was left in an atmosphere of 23 ° C. and 50% RH for 24 hours, and then a dynamic viscoelasticity measuring apparatus RS manufactured by Rheometrics Co., Ltd. was used.
Using AII, at a frequency of 10 Hz, -100 ° C to 2 ° C
The temperature is raised to 100 ° C. at a rate of temperature increase per minute, and the loss tangent ta
The temperature dispersion curve of nδ was measured. The temperature at which this temperature dispersion curve shows a maximum was defined as the main dispersion peak temperature (° C.).

(2) Tensile properties After the sample was left in an atmosphere of a temperature of 23 ° C. and 50% RH for 24 hours, Tensilon RTC manufactured by A & D Corporation was used.
Sample length (distance between chucks) 50 using -1210A
mm, a sample width of 10 mm, and a tensile speed of 500 mm / min, a tensile test was performed, and a tensile strength at break (MPa) and a tensile elongation at break (%) were measured.

(3) Degree of Crystal Orientation The stretching direction of the film is aligned, and the width is 1 mm and the length is 20 m.
m, and stacked so as to have a thickness of 1 mm, and fixed with a cyanoacrylate adhesive to prepare a sample. X-rays were incident on the film surface of the sample in parallel, and imaging was performed with an imaging plate. A rotor flex RU-200B manufactured by Rigaku Corporation was used as an X-ray generator, and CuKα radiation passed through a Ni filter at 30 kV-100 mA was used as an X-ray source. BAS manufactured by Fuji Photo Film Co., Ltd. as an imaging plate
Using SR-127, the sample was exposed for a distance of 60 mm between the sample and the imaging plate for an exposure time of 20 minutes. A diffraction image was read using R-AXIS DS3 manufactured by Rigaku Corporation, and the azimuth angle (β of diffraction at 2θ = 23 ° (which is considered to correspond to the diffraction from the α-type crystal (100) plane of polybutylene terephthalate)) was measured. Angle) An intensity distribution curve was created.
From this β angle intensity distribution curve, X
According to the method for measuring the degree of orientation described in page 81 of the Guide to Repeated Diffraction, Revised Third Edition (preceding June 30, 1985),
From the total value ΣWi (°) of the half widths Wi (°) at two points on the equator line (β angles of 90 ° and 270 °), the degree of crystal orientation (%) was determined by the following equation. Crystal orientation = [(360−ΣWi) / 360] × 100

(4) Oxygen Permeability After a sample having a thickness of 40 μm was left in an atmosphere of 23 ° C. and 50% RH for 24 hours, the oxygen permeability was measured at 30 ° C. and 80% RH using OXTRAN100 manufactured by Mocon. Was measured.

(5) Hot Water Resistance (Hot Water Resistance at 90 ° C.) After the sample was left in an atmosphere of 23 ° C. and 50% RH for 24 hours, two pieces of 100 mm × 100 mm were cut out and overlapped. After the impulse sealing, tap water was added, and the remaining one side was impulse sealed. When immersed in hot water of 90 ° C for 30 minutes and taken out,
Hot water resistance was defined as good when there was no water leakage or significant deformation.

(6) Biodegradability (microbial degradability) The sample was left in an atmosphere of 23 ° C. and 50% RH for 24 hours, and then cut out into a 100 mm × 100 mm size, fixed to a frame, and fixed at 55 ° C. After burying it in the soil for 4 weeks, remove it and lose its original shape due to cracks or missing parts, or less than 50% of the tensile rupture strength compared to the value before filling The microbial degradability was determined to be good when the biodegradability was lowered. When the sample was not decomposed, it was evaluated as defective.

COMPARATIVE EXAMPLE 1 A biodegradable copolyester (BA) containing 50 mol% of a butanediol component, 22.2 mol% of a terephthalic acid component and 27.8 mol% of an adipic acid component as main components.
Ecoflex (trade name) manufactured by SF Co., Ltd.) was press-molded at 200 ° C. to obtain a 210 μm-thick non-oriented sample. The main dispersion peak temperature, tensile rupture strength, tensile rupture elongation and oxygen permeability of the obtained sample were measured to evaluate hot water resistance and biodegradability. Table 1 shows the results.

Example 1: The non-oriented sample obtained in Comparative Example 1 was quadrupled by using a biaxial stretching device manufactured by Toyo Seiki Seisaku-sho at 80 ° C. for 3 minutes at a preheating time of 1.2 m / min. The film was simultaneously biaxially stretched four times in width. After holding for 5 minutes, the film surface was air-cooled to obtain a stretched film. With respect to the film, the same physical properties and the degree of crystal orientation as those in Comparative Example 1 were measured and evaluated, and the difference between the main dispersion peak temperature and the non-oriented sample of Comparative Example 1 was also calculated. Table 1 shows the results.

Example 2 The non-oriented sample obtained in Comparative Example 1 was stretched four times in length using a biaxial stretching device manufactured by Toyo Seiki Seisaku-sho at 85 ° C. for 3 minutes at a preheating time of 1.2 m / min. The film was simultaneously biaxially stretched four times in width. After holding for 5 minutes, the film surface was air-cooled to obtain a stretched film. The physical properties of the film were measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 3 The non-oriented sample obtained in Comparative Example 1 was quadrupled by using a biaxial stretching apparatus manufactured by Toyo Seiki Seisaku-sho at 90 ° C. for 3 minutes and a pulling speed of 1.2 m / min. The film was simultaneously biaxially stretched four times in width. After holding for 5 minutes, the film surface was air-cooled to obtain a stretched film. The physical properties of the film were measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 4: The non-oriented sample obtained in Comparative Example 1 was tripled vertically using a biaxial stretching apparatus manufactured by Toyo Seiki Seisaku-sho at 90 ° C. for 3 minutes at a preheating time of 1.2 m / min. The film was simultaneously biaxially stretched three times in width. After holding for 5 minutes, the film surface was air-cooled to obtain a stretched film. The physical properties of the film were measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 5: The non-oriented sample obtained in Comparative Example 1 was quadrupled vertically using a biaxial stretching device manufactured by Toyo Seiki Seisaku-sho at 100 ° C. for 3 minutes at a preheating time of 1.2 m / min. , Side 4
It was simultaneously biaxially stretched twice. After holding for 5 minutes, the film surface was air-cooled to obtain a stretched film. The physical properties of the film were measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 6 The thickness obtained in Example 3 was obtained by using an ethylene / vinyl alcohol copolymer having an ethylene content of 44 mol% (Eval EF-E manufactured by Kuraray Co., Ltd., thickness: 15 μm) as an intermediate layer. A film having a thickness of 40 μm was laminated on both sides by a conventional dry lamination. The oxygen permeability of this film is 30 cm ³ / m ² · day · atm (30 ° C.,
80% RH).

[0043]

[Table 1]

As is clear from Table 1, the copolyester stretched film of the present invention obtained by biaxially stretching has improved strength and oxygen gas barrier properties more effectively than non-oriented ones. You can see that there is.

[0045]

The stretched copolyester film of the present invention has biodegradability and is excellent in mechanical strength and hot water resistance. Further, the copolyester for a stretched film is excellent in melt processability, so that it can be easily produced, and because the stretch orientation is good, it can be carried out using existing equipment, and is excellent in economical efficiency. The stretched film of the present invention is suitable as a packaging material for various articles such as food, a wrap film, and the like.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B29L 7:00 B29L 7:00 9:00 9:00 C08L 67:02 C08L 67:02 F term (reference) 4F071 AA43 AA44 AA89 AF08 AF08Y AF15 AF15Y AF21 AF21Y AF45 AF45Y AH04 BB08 BC01 BC12 4F100 AK41A AK41J AK69B AL01A AT00B BA01 BA02 DA01 EJ37A GB15 GB16 GB23 JA11A JB06A JD03A JJ03A JK02A JKAAG01A18G01A18G01A01

Claims (6)

[Claims] 1. A butanediol component of 45 to 55 mol%,
Terephthalic acid component 20-30 mol%, adipic acid component 2
0-30 mol%, sulfonate compound component 0-5 mol%
Is a stretched film of copolyester containing as a main component, the tensile breaking strength is 35 MPa or more, the tensile breaking elongation is 180% or more, and the difference between the peak temperature of the main dispersion and the peak temperature of the non-oriented material in the dynamic viscoelasticity measurement. Is 10 ° C. or less and the degree of crystal orientation is 60% or more. 2. The stretched copolyester film according to claim 1, wherein the hot water resistance is 80 ° C. or higher. 3. A film having a thickness of 40 μm at 30 ° C. and 80 ° C.
Oxygen permeability at 1% RH is 1800 cm ³ / m ² · da
The stretched copolyester film according to claim 1, which has a value of y · atm or less. 4. A multilayer film having at least one layer of the stretched film according to claim 1. 5. A packaging container comprising the film according to claim 1. 6. A wrapping film comprising the film according to claim 1.