JPS6147337A - Plastic vessel having excellent gas barrier property - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a plastic container with excellent gas barrier properties, and more particularly to a packaging plastic with good shelf life and a container wall made of a specific thermoplastic polyester. Regarding containers.

BACKGROUND ART Packaging containers manufactured from plastics have excellent light weight and impact resistance, and are therefore widely used for various purposes. Among plastic containers, containers made from polyethylene terephthalate (cPET), especially containers made by biaxial stretch blow molding, have better gas barrier properties than containers made from polyethylene or polypropylene. It can be said that it has outstanding transparency and impact resistance, and gas permeation through the vessel wall is
Compared to glass bottles and metal containers, these containers cannot be ignored, and the shelf life of beer, beverages, etc. using these containers is limited to a relatively short period of about 2 to 4 months.

Conventionally, many proposals have been made to utilize various gas barrier resins to improve the preservation of the contents of plastic containers. For example, ethylene-vinyl alcohol copolymer (saponified ethylene-vinyl acetate copolymer) has one of the lowest oxygen permeability coefficients among various resins. Many proposals have been made to reduce the gas permeability of the container as a whole by laminating polyethylene terephthalate or polyolefins as inner and outer surface layers. Ru.

Deer 1. Therefore, even if the ethylene-vinyl alcohol copolymer described above has a small gas permeability coefficient for oxygen etc. under conditions of low humidity, it has the disadvantage that the coefficient of gas permeability increases by about one order of magnitude under conditions of high humidity. be.

Purpose of the Invention The present inventors have discovered that among various thermoplastic polyesters,
Polyester containing a certain concentration or more of ester repeating units in which the number of carbon atoms in the hydrocarbon group interposed between adjacent ester carbonyl groups or esteroxy groups is 1 has excellent gas barrier properties against oxygen, carbon dioxide, etc. It has also been found that its gas barrier properties have little dependence on humidity, making it extremely excellent as a container construction material.

Therefore, an object of the present invention is to provide a plastic container for packaging whose wall is made of a specific thermoplastic polyester that has a small permeability coefficient for gases such as oxygen, carbon dioxide, and water vapor, and also has a small humidity dependence of this gas permeation coefficient. It is on offer.

Another object of the present invention is to provide a specific material that can be easily laminated to polyethylene terephthalate, etc., which are conventionally used in plastic containers, and that, in this laminated state, significantly superior gas barrier properties and glabella peeling resistance can be obtained. The present invention provides a composite plastic container for packaging comprising a polyester layer.

Structure of the Invention According to the present invention, the polymer chain is mainly composed of ester repeating units, and the number of carbon atoms in the hydrocarbon group interposed between adjacent ester carbonyl groups or esteroxy groups is 1.
containing at least 25 moles of ester repeating units with a density at 25tZ' of at least 1.340 Y/
There is provided a plastic container with excellent gas barrier properties characterized in that the container wall is made of a thermoplastic polyester having a softening point of CRD or higher and 320C or lower.

Preferred embodiments of the invention The present invention will be explained in detail below.

Structure and physical properties of polyester Generally, thermoplastic polyester has the following formula, H+,
Each of R2 and R3 represents a divalent hydrocarbon group, and is composed of two types or a combination of two or more types of repeating units.

The thermoplastic polyester used in the present invention is an ester repeating unit in which the number of carbon atoms in the hydrocarbon group interposed between adjacent Unister carbonyl groups (-C-) or i'i ester Oyashi groups (-0-) is 1. A distinctive feature is that it contains at least 25 molt.

In this specification, the molten content of ester repeating units refers to a value calculated based on the following criteria. That is, the above formula (1)
In the case of a repeating unit, when the number of carbon atoms in RI is 1,
The repeating unit defined above is counted as one. Further, in the case of the repeating unit of formula (2), when the number of carbon atoms in each of R2 and R3 is 1, one of the carbon atoms of R2 and Rs is 1, with the repeating unit defined above being 1. , when the other carbon number is other than 1, each calculation is made assuming that the number of repeating units specified above is 0.5.

The present invention calculates 25 ester repeating units in which the number of carbon atoms in the hydrocarbon group interposed between adjacent ester carbonyl groups or esteroxy groups is 1, calculated using the calculation method described above.
This is based on the new finding that polyesters containing more than 10% of molt exhibit significantly superior gas barrier properties compared to thermoplastic polyesters conventionally used in plastic packaging containers, such as polyethylene terephthalate.

In its simplest form, the thermoplastic polyester used in the present invention can take the form of a polyester consisting of repeating units of the formula O, ie, a poly(oxyacetate), which can also be used in the amorphous portion. It has a significantly high density, for example, the density (25C) of the amorphous part of polyethylene terephthalate is 1.335 s'/cc.
At arunoni vs. shite, 1,60 r/cco density (25r
') is shown. It will be appreciated that this density is exceptionally high for an organic polymer composed of light atoms of carbon, hydrogen, and oxygen.

The thermosetting polyester used in the present invention exhibits excellent gas barrier properties because even in the amorphous portion, molecular chains are densely packed, as shown by the high density mentioned above. It is assumed that this is due to the fact that it has a tightly packed structure that does not allow gas to pass through.

In the present invention, it is also extremely critical that the divalent hydrocarbon group between the ester carbonyl group and the esteroxy group has 1 carbon number, and for example, the intervening hydrocarbon group When the number of carbon atoms is 2, that is, when the polyester is poly(β-probiolactone), the density decreases to 1.42 f/hiro, and the softening point and mechanical properties decrease to significantly lower values.

In addition to those containing the above-mentioned oxyacetate units, the thermoplastic polyesters used in the present invention include those containing ester units derived from malonic acid and glycols, and those containing ester units derived from dicarboxylic acids and methylene glycol. Examples include those containing units or those containing ester units derived from malonic acid and methylene glycol.

Of course, these polyesters do not need to be homopolyesters, and even if they are copolyesters containing two or more of the above-mentioned ester units, they may contain other ester units in the main chain in addition to the above-mentioned ester units. It may be a copolymerized polyester. Furthermore, it may be a blend of two or more of these homopolyesters or copolyesters, or a blend of these and other polyesters or copolyesters. What is important is that the copolyester or polyester blend as a whole contains the ester repeating units defined by the invention in an amount of at least 25 moles, particularly preferably at least 35 moles. When the content of this ester repeating unit is less than the above range, the effect of improving gas barrier properties will be small.

Monomer components used to construct ester repeating units other than the ester repeating units defined in the present invention include β
-propioladone, γ-butyrolactone, δ-capryllactone, ε-caprolactone, oxybenzoic acid, hydroxyphenylacetic acid, β-hydroxyethylbenzoic acid,
β- and oxycarboxylic acids or lactones such as droxyethylphenylpropionic acid; conolic acid, adipic acid, geltaric acid, cepatic acid, dodecadicarboxylic acid, terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, naphthalene dicarboxylic acid , 2.Dicarboxylic acids such as 2-bis(4-carboxyphenyl)propane; ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, cyclohexanediol, xylylene glycol, diethylene glycol, triethylene glycol, 2. Diols such as 2-bis[4-hydroxyphenyl]propane can be mentioned.

These polyesters must, of course, have sufficient molecular fit to form a film, and must be heated at 60C in a mixed solvent of cresol and tetrachloroethane (1:1 weight ratio). The polyester used in the present invention preferably has a reduced viscosity of 0.5 d/r or more when measured at a 0.5 P/#O concentration.
The density is at least 1.340 S' when measured at a temperature of
/ ad or more, especially 1.37 C1/i or more is important in relation to gas barrier properties. In this specification, the minimum density of 1.340 r/cc means that the polyester is 1.340 r/cc even in the amorphous part.
It means exhibiting a density of C or higher. Of course, even in this polyester, the density of the crystallized region exhibits a thicker b value than the density of the amorphous region, as in a normal crystalline polymer. It is generally known that the gas permeability coefficient of a polymer is greatly influenced by the content of amorphous moieties in the polymer. In the present invention, by setting the density of the amorphous part in the polyester to 1.340j'/- or more, gas permeation through the amorphous part is also suppressed to a low level,
The overall gas permeation is limited to low values.

Further, the polyester used in the present invention should have a softening point (ring and ball method) of 320C or less, preferably 300C or less, so that it can be molded into a container.

The polyester used in the present invention exhibits high gas barrier properties because it has the above-mentioned ester backbone chain structure and high density, and this high gas barrier property is not impaired even under high humidity conditions. do not have. For example, this polyester has a significantly lower oxygen permeability coefficient than that of polyethylene terephthalate. ．． 25C, 0%
The oxygen permeability coefficient at RH is 1. OX 10”cC-W
cnhyx・CmH,9 is smaller than 25U,97
Even under high humidity conditions at %RH, the value increases by only 20φ at most, and there is almost no humidity dependence of the oxygen permeability coefficient. This applies similarly to gases other than oxygen, such as carbon dioxide and nitrogen.

The ester-forming monomer used in the present invention is known per se, and can be produced as a polyester by a manufacturing method known per se, such as a transesterification polymerization method or a ring-opening polymerization method.

These polyester resins are used for various purposes, such as improving thermal stability, and are especially used for their excellent gas barrier properties.
Mixing agents that are well known per se, such as nucleating agents, stabilizers, lubricants, antioxidants, ultraviolet absorbers, pigments, fillers, plasticizers, etc., must be added according to known prescriptions within a range that does not impair properties. I can do it.

Production of containers The molding into containers involves melt-extruding the aforementioned thermoplastic polyester alone or in combination of two or more into a parison shape.
It is easily obtained by blow molding, in which an extruded parison is supported in a split mold and a fluid is blown into the mold. Also,
In order to improve the impact resistance and transparency of the container, a parison or preform is produced in advance by melt extrusion or injection molding, and this parison or preform is stretched at a stretching temperature below its melting point. It is also possible to make a plastic container which is mechanically stretched in the axial direction and also stretched in the circumferential direction by blowing fluid, so that the molecules are blended in the biaxial directions.

Furthermore, the present invention also applies to wide-mouthed containers such as wide-mouthed bottles and cup containers made by drawing or stretching a sheet or film previously formed from the polyester by vacuum forming, pressure forming, plug-assisted pressure forming, etc. It can be applied advantageously.

Despite having a high density, the polyester used in the present invention has the distinct advantage of being easy to thermoform. Therefore, it has the advantage that it can be molded into containers extremely easily compared to ordinary PET and the like.

The polyester used in the present invention also has a relatively low crystallization rate. By quenching the melt-extruded or injected resin, parisons, preforms, films, sheets, etc. for molding containers of amorphous shapes can be easily obtained, and these parisons, etc. are produced at relatively low temperatures. It can be easily formed into the final container, and molecular orientation can be imparted to the container wall. Of course, this final container can also be heat treated to heat-set the molecular orientation or to improve its crystallinity.

The wall thickness of plastic containers can be varied over a wide range, from relatively thin containers such as so-called squeeze containers or lightweight cups to relatively thick containers such as rigid containers. The mass per product is 0
．． An appropriate value may be selected from the range of 001 to 52/go depending on the end use.

This high-density polyester can be used as a packaging container in its own form, but also in the form of a laminate with other resins such as conventional polyesters, e.g. polyethylene terephthalate, polycarbonate or polyolefins. . For example, since this polyester shares the same types of repeating units as ordinary polyesters such as polyethylene terephthalate, it is recognized that it can be thermally bonded relatively easily. Of course, sufficient adhesion may not be obtained depending on the combination of resins and molding or processing conditions, but in this case, a blend of both resins or another thermal adhesive, such as a copolyester thermal adhesive, may be used. A satisfactory laminated structure can be obtained by interposing the above.

Moreover, since this high-density polyester has excellent moldability and processability, it is possible to improve moldability and processability by forming a laminate with other resins that are difficult to mold.

Formation of the laminate is preferably carried out by multilayer coextrusion.

According to this multilayer coextrusion, since both resins are well mixed at the adhesive interface between the two resins, a PR layer structure having particularly excellent adhesive strength can be obtained. For multilayer coextrusion,
The above-mentioned high-density polyester and other thermoplastic resin,
If necessary, adhesive resin is interposed in between and extruded through a multilayer die to produce films, sheets, bottle pipes,
Molded into a bottle preform, etc.

The laminate can be formed by a method called sandwich lamination or extrusion coating. For example, a laminate can be produced by extruding an adhesive into a thin film between a pre-formed high-density polyester film and another resin film, and pressing them under heat if necessary.

Furthermore, when molding a multilayer preform, a method of manufacturing a multilayer preform by simultaneously or sequentially injecting high-density polyester and other resins may also be adopted.

The laminate can be molded into a container by the molding method described above. When choosing polyethylene terephthalate or polycarbonate as the other resin to be laminated,
A container with excellent creep resistance, transparency, etc. can be obtained, and when polyolefins are selected, a container with excellent flexibility, softness, squeezing properties, etc. can be obtained. When high-density polyester is A1 and other resin is B, A/B, , B/A/
It takes any laminated structure such as B. be able to. The thickness of high-density polyester is 5 μm from the viewpoint of preventing gas permeation.
It is preferable that the thickness be larger than the door, particularly 10 μm or larger.

In addition, this high-density polyester has the property of being relatively compatible with ordinary polyesters such as polyethylene terephthalate and polybutylene terephthalate, so even if a considerable amount is blended, the gas barrier of the molded product will be affected.
This has the advantage that not only the transparency is improved but also the transparency is hardly impaired. The fact that this high-density polyester can be used in the form of a blend with conventional polyester provides another advantage in that it facilitates the utilization of scraps produced during the manufacture of containers in the form of laminates as described above. When using this high-density polyester as a blend, it depends on the form and purpose of use, but by containing at least 15 parts of the high-density polyester as a blend ratio, excellent gas barrier properties are ensured when used alone. .

According to the present invention, since the gas barrier property is excellent and the humidity dependence of the gas barrier property is small, a container with excellent long-term storage of contents can be obtained, and this polyester has heat resistance, hot water resistance, and creep resistance. Because of its excellent elasticity, impact resistance, and mechanical strength, it is a packaging container that satisfies the properties of a container even if it is relatively thin, and can also be subjected to hot filling or retort sterilization. provided.

The invention is illustrated by the following example.

Example 1 Dimethyl terephthalate as a dibasic acid component, ethylene glycol as a glycol component, and four catalysts were placed in a flask and transesterified with stirring. The reaction starts from 165C and reaches 230C at 0.5C/mlr.
The temperature was raised at a temperature of 90%, and 90% of the theoretical amount of methanol was eluted 11.0 minutes after the start of the reaction.

Then, the temperature was increased to 27 CI''-j for 60 minutes to 0.1 ra.
Polymerization was carried out for 6 hours at n If g (Resin I). on the other hand,
Glycolide prepared by recrystallization was subjected to open R polymerization at 170C under reduced pressure for 7 hours in the presence of a titanium catalyst (resin 1f). Next, add resins ■ and ■, respectively.

Under reduced pressure melting at 27 Orr, a coloring inhibitor was added, mixed at a weight ratio of 1:1, and melt-polymerized for further 1 hour.

0,5f'/d of the obtained polymer CHBR-1) using 7enol/6chlorinated phenol at a mixing ratio of 10:7 as a solvent.
The reduced viscosity at the concentration of lj and 3C1r is 0.8#/f
'Met. In addition, the final composition of this polymer was determined by NMR.
As a result of analysis and confirmation by gas chromatography, the C2 content was 66 mol.

Next, this block resin was molded into a 50 μm film using a hot press, rapidly cooled in water, dried at room temperature, and the following physical properties were measured.

The density was 1.4 when measured using a density gradient tube.
It was 66f/Cn. Moreover, the softening temperature by the ring and ball method was 242C. Additionally, the glass transition temperature (T9) was measured using a Perkin-E1mer differential thermal analysis method.
Diffuzioq in p.
olrymtrs ” J, Crank, G, S.

park Ed, Actemic press L
oncton anti New York (196
8) Referring to the apparatus of Cap'I, 5cLrrer et al., it was measured by the high vacuum method, and it was 5.6X 1Q.
-1JCr:, -(-@/al-ss=.cmHq.

Next, the weight ratio of phenol/tetrachloroethane is 50
Intrinsic viscosity at 30C in a mixed solvent of 150 is 0.9
1d/V polyethylene terephthalate resin (PEr)
is the outermost layer resin, HBR-1 is the middle layer, and the extruder for the outermost layer is equipped with a full-flight screw with a diameter of 65mm and an effective length of 1430m.The diameter is 68cm and the effective length is 950m. Intermediate layer extruder with built-in full-flight screw, feed pipe, and 22! PET/
A 6-layer HBR-1/PET pipe is melt-extruded and pre-blow molded in a split mold to form a bottomed preform with an inner diameter of 27.7 mm, a length of 138 mm, and an average wall thickness of 6.5 mm. did. Furthermore, pET/HBR-1 of this preform
The weight ratio of /pET is 50:15:3 from the outside.
The extrusion conditions were set so that the result was 5.

This bottomed preform was heated with an infrared heater, and the maximum temperature of the bottomed preform was 108C.

After setting the minimum temperature to 98C, sequential biaxial stretch blow molding was performed to obtain an axial stretch ratio of 2.0 times and a circumferential stretch ratio of 6.0 times.
Stretch blow molded so that it is 0 times, and the average wall thickness is 0.40
no++, inner volume 1040CC, bottle weight 667
I created a bottle.

In addition, as Comparative Example 1, polyethylene terephthalate 1<P
A bottomed preform with the same dimensions as above was molded using only ET), and then a biaxially stretched blow bottle with the same dimensions was manufactured in the same manner as above.

Furthermore, as Comparative Example 2, the vinyl alcohol content was 6
9 molti, residual vinyl ester concentration is 0.6 mol%, 8
Two-handed vinyl alcohol copolymer resin (pEVA) with a point of 182iC is used as the intermediate layer resin, and six types and five eyebrows are interposed between the outer layer and the intermediate layer with a copolyester adhesive resin layer (ADH). PET/ADH/PEVA/ADH/PET using an extrusion molding device combining dies.
The composition ratio of the 5-layer pipe by weight is 50/3/9/
The extrusion conditions were set to give a ratio of 3/35.

Further, from this preform, a biaxially stretched blow bottle of the same size was manufactured in the same manner as above.

These bottles were evaluated for bottle transparency (haze), oxygen permeability, and drop impact strength using the methods shown in the footnotes of Table 1. Furthermore, after filling the synthetic carbonated beverage so that the gas volume is 4.0 νol at room temperature, the relative humidity is 50C2 CR.
, H,) stored in an atmosphere of 35 and 80 degrees, respectively.
Measure the gas volume after 3 months and find the initial value (4,0
The rate of decrease based on υol) was expressed as a percentage.

Table 1 shows these results.

Example 2: Resin (1) in Example 1 was further polymerized at 230C for 1 hour (CHBR-2), and CHBR-3 to CHBR-5 (CHBR-2) in which the same melt polymerization was performed by changing the ratio of resin I and resin (2). 0
R-1,2). The reduced viscosity, C1 content and various physical properties of these polymers were measured according to the method described in Example 1 and are shown in Table 2.
It was shown to. Furthermore, multilayer bottles having the same dimensions as in Example 1 were prepared using these polymers, and the performance was evaluated, and the results are shown in the same table.

Example 3゜In Example 1, polymerization was carried out according to the same procedure as in Example 1 except that a resin having the respective composition ratios of dibasic acid component and glycol component shown in Table 6 was used as resin I. . However, in the polymerization of resin (1), polymerization conditions ranging from 220 to 29 Or and from 1 to 7 hours were adopted depending on the respective copolymerization components. Table 3 shows the composition of these resins and the physical properties measured in the same manner as in the previous examples.

Next, the weight ratio of phenol/tetrachloroethane is 501
Intrinsic viscosity at 3CI in 50% mixed solvent is 0.85
d/S' polyethylene terephthalate (PE"r) as a polyester layer, and each resin shown in Table 3 as a separate layer (H
For the BR layer), an extruder with a built-in screw with a diameter of 50 m and an effective length of 1600 m is used as an extruder for the polyester layer, and an extruder with a built-in screw with a diameter of 68 m and an effective length of 950 m +++ is used for the HBR layer. Using a specific extruder, a two-layer feed block, a single manifold F-type die, and a five-roll sheet forming device were used to form the pET layer lH.
The total thickness of the B R layer is 207++I211 (pET
/HBR=80/20 thickness ratio], a two-layer sheet with a width of 400 mm was molded.

The sheet is sufficiently rapidly cooled to prevent the PET layer from crystallizing (
The density of the PET layer of the obtained sheet was 1.3395'/i
It was below. ), and since the sheet cannot be rolled,
After forming, use a traveling cutter to cut the length to 1000m+
It was cut into Next, the obtained sheet was heated with an infrared heater for 10 minutes.
After heating to 0~125C, use plug assist vacuum/pressure forming machine to form flange width 5M%, mouth inner diameter 60rutt, bottom outer diameter 40mm.
It was molded into a cup with an inner wall made of PET layer with a height of about 80 mm.

For these cups, footnote to Table 1 of Example 1 above*
According to the method described in 2, the oxygen permeability was measured under conditions in which the humidity outside the container was adjusted to relative humidity R, H, ") 5% and 80%, respectively.

(Note) Abbreviation symbol (common to Table 31 and Table 4) Dibasic acid component> TPA Terephthalic acid IPA Isophthalic acid AA Adipic acid MA Malonic acid SA Succinic acid Glyfur component> EG Ethylene glycol 8G 1.4-Butanediol DEC Diethylene glycol HD 1.6-Hexanediol CHOM
Cyclohexane dimethylene glycol 1.4-CHD
1.4-Cyclohexane glycol p-HQ Parahydroquinone Example 4 2 Dimethyl isophthalate (33 mol% as acid component), dimethyl malonate (67 mol% as acid component), ethylene glycol and catalyst as glycol component Transesterification was carried out while stirring in a two-cell flask.The reaction started at 185C and reached 230C at a rate of 0.5C/
The temperature was raised to 50 m, and 90 m of methanol, the theoretical amount, was eluted 110 minutes after the start of the reaction. Then 2700 in 30 minutes
The temperature was raised to 0.1 mHq and polymerization was carried out for 4.5 hours (
HBR-15). Furthermore, each polymer was obtained using the charging composition shown in Table 4 under almost similar polymerization conditions. As for H/3R-i3, during the polymerization reaction, resin (1) of Example 1 was added at a weight ratio of 6:1, and melt polymerization was further carried out for 1 hour. The table shows the resin composition estimated from the charging ratio and the physical properties of the resin measured according to the method described in Example 1.

Using these resins for the intermediate layer, according to the method described in Example 1 above, the average wall thickness was 0.40 and the hollow volume was 1040.
A two-type, three-layer blow bottle with a CC weight of 569 was produced.

Performance evaluation was performed on these bottles in the same manner as in Example 1. Table 4 shows these results.

Implementation example 5. (Invention 19) 70 mol of dimethyl inphthalate as a dibasic acid component,
30 mol of dimethyl terephthalate, ethylene glycol as a glycol component, and four catalysts were placed in a flask and transesterification was carried out with stirring. The reaction is 165
Start from c, raise temperature at 230C''!, o, 5r:/=,
90% of the theoretical amount of methanol was accumulated 110 minutes after the start of the reaction.

Next, glycolide purified by recrystallization was added together with the catalyst at a ratio of 2:1, and the temperature was raised to 27°C under reduced pressure for the first 3 hours.
The temperature was increased to DC and melt polymerization was further carried out for 1 hour.

Measurement of physical properties of the polymer (HBR-19) obtained in the same manner as in the previous example I1. As a result, the C1 content was 46 molti, the ring element viscosity was 0.85 J/litre (density 1.431//, Tq
59'C, Tm 24'IC, Pot25C6, 7
X 10-”cc-crn/i “SeC”ffi H
It was q.

Using this resin, the average wall thickness was 0.40B and the internal volume was 1040CC according to the method described in Example 1 above.

A single-layer stretched blow bottle weighing approximately 382 kg was produced. Next, performance was evaluated using the method in the footnotes of Table 1.
Transparency 4.4 cm, oxygen permeability 1.1 cc/day
α2m, there was no damage in the drop impact test, and the carbon dioxide loss was 5.8 inches at RH 55 inches and 17% at RH 80 inches, showing completely good performance.

Example 6゜Resin HBR-2 used in Example 2 and phenol/tetrachloroethane in a mixed solvent with a weight ratio of 50150 at 30C
The intrinsic viscosity at 0.84. After tri-blending #15' polyethylene terephthalate (pEr) resin at the mixing (weight) ratio shown in Table 5, a single-layer bottle was created according to the same procedure as in Example 5, and the performance was evaluated. . The results are shown in Table 5. The same table shows the physical properties of the blend resin, including the C1 content calculated from the blend ratio and the physical properties measured for a sheet made from the tri-blend resin using an extruder.

For comparison, the above pET and the ethylene-vinyl alcohol copolymer resin (p EVA) used in Comparative Example 2 were also used.
), single-layer bottles of the same dimensions were made from melt-mixed pelletized resin and evaluated in the same way.

Claims (1)

[Claims] (1) The polymer chain is mainly composed of ester repeating units, and contains at least 25 mol% of ester repeating units in which the hydrocarbon group interposed between adjacent ester carbonyl groups or esteroxy groups has 1 carbon number. The container wall is composed of a thermoplastic polyester having a density of at least 1.340 g/cm^3 or more at 25°C and a softening point of 320°C or less, which has excellent gas barrier properties. plastic container.