JPH0482100B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a stretch-blown polyester container and a method for manufacturing the same, and more particularly, to a stretch-blown polyester container and a method for manufacturing the same, and more particularly, to a stretch-blown polyester container and a method for manufacturing the same. The present invention relates to a container comprising stretch-blow molding a multilayer plastic preform comprising a polyarylate or its composition in the upper part and the closed bottom part, and an intermediate layer comprising a gas barrier resin in the other parts, and a method for manufacturing the same.

(Prior art and its problems) Polyester containers made by stretch blow molding are
Even though they have excellent transparency, moderate rigidity, impact resistance, excellent dimensional stability under normal conditions, and almost satisfactory gas barrier properties, cans and bottles have almost zero gas permeability. , it has a non-negligible permeability to oxygen and carbon dioxide, and the shelf life of its contents is limited to a relatively short period.

Furthermore, when filling fruit juice drinks, high temperature sterilization,
In particular, for containers that require sterilization of the container mouth, when temperature and pressure, especially both of these, are applied, parts that are thicker than the body, such as the container mouth and closed bottom, may be sterilized.
In areas where molecular orientation is insufficient due to biaxial stretching of thermoplastic polyester, deformation may occur and volumetric expansion may occur. Furthermore, since the container opening is the part most susceptible to impact during cap tightening and handling, it also has the disadvantage of being unsatisfactory in terms of deformation resistance, impact resistance, etc.

Furthermore, when forming a multilayer preform by the co-injection molding method, a layer structure is generally adopted in which the inner and outer surface layers are thermoplastic polyester and the intermediate layer is a gas barrier resin. 51-2773), it is recognized that there are drawbacks regarding the thickness distribution of each layer within the multilayer preform.

That is, the position of the gas barrier layer (intermediate layer) in the thickness direction at the bottom of the preform is biased inward, and the thickness of the inner surface layer polyester is significantly reduced at the bottom. For example, the ratio of the thickness of the outer surface layer (A) to the thickness of the inner surface layer (B) is A:B = 2:1 at the body, but it becomes A:B = 5:1 at the bottom. In addition, the thickness of the bottom inner surface layer is significantly reduced.

The reason for this is that the gate through which molten resin flows into the cavity of the injection mold is provided at the bottom, and therefore other parts are at high temperature.
This is thought to be because the resin on the inner surface of the bottom is also subjected to pressure that causes it to flow to other parts.

When the bottom inner surface layer becomes thinner in this way, the inner surface layer becomes even thinner during stretch blow molding, and in severe cases, the gas barrier layer tends to be exposed inside, causing moisture absorption of the gas barrier layer from the contents. This may increase the gas permeability of the intermediate layer or cause delamination between the intermediate layer and the polyester layer.

As with the bottom, the container mouth also includes an outer surface layer to provide threads for cap engagement;
This results in a significant reduction in the thickness ratio of the inner surface layer.

Therefore, an object of the present invention is to manufacture a multilayer preform used for manufacturing a multilayer stretch blow-molded container by co-injection molding, so that the ratio of the thickness of the polyester inner surface layer to the polyester outer surface layer is constant in any part of the preform. Moreover, by sealing polyarylate or its composition in the container mouth, preferably the closed bottom, and a gas barrier resin in other parts between these polyester inner and outer surface layers, the container mouth and the closed bottom can be sealed. It is an object of the present invention to provide a stretch blow-molded container having a structure with improved deformation resistance and excellent gas barrier properties, and a method for producing the same.

(Means for Solving the Problems) According to the present invention, a stretch blow molding is produced by stretch blow molding a polyester preform, and has a thick mouth part, a biaxially stretched thin body part and a closed bottom part. In the polyester container, at least the inner and outer surfaces of the container as a whole are formed of polyethylene terephthalate, the mouth is formed of inner and outer layers of polyethylene terephthalate and an intermediate layer of polyarylate or a composition thereof, and the body is formed of polyethylene terephthalate. A container is provided, characterized in that it is formed of inner and outer layers of polyethylene terephthalate and an intermediate layer of gas barrier thermoplastic resin.

According to the present invention, there is further provided a method for producing a turned-blown polyester container, which comprises producing a preform mainly made of polyester by injection molding, and stretch blow molding the preform in a mold at a temperature that allows the preform to be stretched. Correspondingly, the polyethylene terephthalate corresponding to the inner layer is made into a solid flow, the polyethylene terephthalate corresponding to the outer layer is made into an outer annular flow, and the polyarylate corresponding to the intermediate layer or its composition is made into an inner annular flow, which are fed into the injection mold in parallel. Corresponding to the body of the container, polyethylene terephthalate corresponding to the inner layer is produced in a solid flow, polyethylene terephthalate corresponding to the outer layer is produced in an outer annular flow, and thermoplastic resin made of gas barrier is produced as an intermediate layer in an inner annular flow. A method for producing a stretch-blown polyester container is provided, which comprises co-injecting the polyester container in a parallel manner into an injection mold.

(Function) In FIG. 1 showing an example of the structure of the container of the present invention, the container 1 has a mouth portion 2, a closed bottom portion 3, and It consists of a body part 4, and a screw 5 is cut on the outer surface of the mouth part 2 to engage with the cap.

In FIG. 2, which is an enlarged sectional view of the container mouth of the present invention, the inner and outer surface layers of the container mouth are made of a thermoplastic polyester resin 6, and the intermediate layer between the inner and outer surface layers of the mouth contains polyarylate or its composition. An intermediate layer made of a substance 7 (hereinafter sometimes simply referred to as polyarylate) is located, and the intermediate layer below the mouth part is made of a gas barrier resin 8.

Similarly, in FIG. 3, which is an enlarged sectional view of the container closed bottom of the present invention, the closed bottom 3 has thermoplastic polyester resin 6 as its inner and outer surface layers, and as an intermediate layer,
It is composed of polyarylate or its composition 7.

Polyarylate used for the intermediate layer of the container mouth and closed bottom has a glass transition point of around 200°C and has the advantage of being excellent in heat resistance, but has poor stretch formability, especially when polyester It has the disadvantage that stretch blow molding is difficult due to the laminated form. According to the present invention, by using this polyarylate or a composition thereof as the intermediate layer of the container opening and the closed bottom, which have a low degree of molecular orientation, deformation resistance and
This makes it possible to provide impact resistance.

Furthermore, since a gas barrier resin is sealed as an intermediate layer in the body of the container, it is possible to obtain high gas barrier properties without impairing the flavor characteristics of the contents. .

Furthermore, by manufacturing according to the method of the present invention described below, the ratio of the thickness of the outer surface layer and the inner surface layer is
Since the intermediate layer remains substantially the same in any part of the preform where it is present, the gas barrier resin and polyarylate or its composition are not exposed inside.

In FIG. 4, which conceptually shows a simplified cross-sectional structure of the multilayer die used in the method of the present invention, the multilayer die 9 includes a polyester solid channel 10 corresponding to the inner surface layer of the multilayer preform, and a polyester solid channel 10 corresponding to the inner surface layer of the multilayer preform. Outer annular channel 11 for polyester corresponding to the outer surface layer, and gas barrier resin and polyarylate or composition thereof corresponding to the intermediate layer (gas barrier resin and polyarylate or composition thereof) of the multilayer preform between these Inner annular channel for objects 1
2 are provided respectively, and each of these channels 10, 1
1 and 12 open into a single hot runner nozzle 13 which is connected to an injection mold gate (not shown).

In FIG. 5, which shows the schematic arrangement of the equipment used to carry out the method of the present invention, an injection machine 14 for the inner layer polyester, an injection machine 15 for the outer layer polyester, an injection machine 16 for the middle layer polyarylate, and an injection machine 16 for the middle layer gas barrier resin. An injection machine 17 is provided respectively. Each of these injection machines has their respective tip nozzle 1
4a, 15a, 16a, 17a to the corresponding runners 14b, 15 of the hot runner block 13.
b, 16b, and 17b, respectively. The hot runner nozzle 18 has a solid channel 10 for the inner layer polyester at the center, an annular middle annular channel 12 for the intermediate layer located around it, and an outer annular channel 11 for the outer layer polyester located on the outer periphery. These channels are arranged to join near the tip of the hot runner nozzle 18. In the multilayer die shown in FIG. 4, the first solid channel 10 corresponds to the injection of the inner layer of the preform, the inner annular channel corresponds to the injection of the intermediate layer of the preform, and the outer annular channel 11 corresponds to the injection of the outer layer of the preform. 1 for hot runner block 13
Although only one hot runner nozzle is shown, it should be understood that multiple hot runner nozzles may be provided. A cavity mold 19 is provided above the block 13 and is integrally fastened thereto. Cavity type 19
is provided with a cavity 20 whose axis extends in the vertical direction, and this cavity 20 is connected to the hot runner nozzle 18 of the block 13 through a gate 21.
connected to. Naturally, the number of cavities 20 corresponding to the number of hot runner nozzles 18 are provided in parallel.

A core 22 that defines the inner surface of the preform during molding and a neck grip split mold (not shown) that defines the outer periphery of the preform mouth during molding are provided to be combined with this cavity mold 19 during injection molding.

First, for injection molding, each injection machine, hot runner block, and injection mold are in the state shown in FIG. 2 described above.

At this position, the screw of the inner layer injection machine 14 moves forward, and the polyester resin is injected into the nozzle 14a,
A small amount of resin is injected into the cavity 20 through the inner layer resin runner 6b, the solid channel 10 in the hot runner nozzle, and the gate 21. The screw of the injection machine 15 for the outer layer and the screw of the injection machine 16 for the intermediate layer polyarylate are moved forward with a slight delay in timing. As a result, the outer layer resin is supplied to the tip of the hot runner nozzle 18 through the nozzle 15a, the runner 15b, and the outer annular channel 11, and the middle layer polyarylate is supplied to the tip of the hot runner nozzle 18.
a, the runner 16b, and is supplied to the tip of the hot runner nozzle 18 through the inner annular flow path 12. When the amount of polyarylate corresponding to the intermediate layer at the mouth of the container has been injected, the injection machine is stopped, and the injection machine 17 for gas barrier resin for intermediate layer starts injecting the gas barrier resin. At the point when the polyarylate is continuous with the polyarylate injected earlier in the inner annular flow path, the inner surface layer polyester injection machine 14 and the outer surface layer polyester injection machine 15 are operated again (see FIGS. 6 and 7). .

In the present invention, polyester for the inner surface layer,
The polyester for the outer surface layer, the polyarylate for the intermediate layer or its composition, and the gas barrier resin are injected translationally into the injection mold through the channels and gates of the hot runner. In this specification, "translationally injecting" means that each resin is injected simultaneously through each channel in a uniform state, and therefore means that the flow rate ratio between each resin is constant. .

In addition, in the present invention, as described above, the timing of injection of the polyarylate or its composition for the intermediate layer corresponding to the container opening is set earlier than the injection timing of the polyester for the inner and outer surface layers. After injecting the polyarylate or its composition in an amount corresponding to the mouth part by starting slightly later, the gas barrier resin is started to be injected. At this time, the injection of the thermoplastic polyester is also stopped at the same time as the polyarylate or its composition is stopped, and the thermoplastic polyester is injected again at the same time as the gas barrier resin starts to be injected. It is important to eject at a time when this will not occur.

Then, in the injection of the container closing bottom part,
The injection of the intermediate layer gas barrier resin 8 and the thermoplastic polyester 7 of the inner and outer surface layers is stopped, and the intermediate layer is changed to polyarylate or its composition 7, so that no cavities or bubbles are formed in the intermediate layer, as described above. Then, the thermoplastic polyester and polyarylate or their compositions are again injected. At the end of injection,
The injection of polyarylate or its composition is controlled to be completed slightly earlier (see FIG. 8).

According to the present invention, since the injection flow rate of the polyester for the inner surface layer is maintained constant throughout substantially the entire injection process, the thickness of the outer surface layer and the inner surface layer of the preform to be formed is will remain substantially the same in any part of the preform where the interlayer is present. For example, if the thickness of the outer surface layer at the center of the body is A, the thickness of the outer surface layer at the bottom is A', the thickness of the inner surface layer at the center of the body is B, and the thickness of the inner surface layer at the bottom is B', then the formula The relationship A/B=A'/B' holds true, and in particular, it is also possible to set A=B and A'=B'. Of course, since the injection flow rate of the gas barrier resin is constant, the thickness (C) of the intermediate layer is also constant at any part of the preform.

In addition, by slightly shifting the injection start point of the polyarylate or its composition for the intermediate layer, it is possible to prevent the polyarylate or its composition from being exposed to the uppermost opening of the preform, and furthermore, the polyarylate or its composition can be prevented from being exposed to the uppermost opening of the preform. By shifting the injection end point slightly earlier, the bottom part of the preform corresponding to the gate can also be formed only of polyester, thereby preventing exposure of the polyarylate or its composition.

The injection of the polyester prior to the injection of the polyarylate or its composition may be performed using either the polyester for the inner surface layer or the polyester for the outer surface layer, or may be performed using both.
As a preferred example, the pre-injection is carried out with polyester for the inner surface layer and the post-injection is carried out with polyester for the outer surface layer.

The multilayer preform obtained by the co-injection molding method of the present invention is used for stretch blow molding into multilayer containers.

Prior to this stretch-blow molding, the multilayer preform is first heated at the stretchable temperature of the main resin layer, then at the stretching temperature of the polyester, generally 80 to 135°C, especially 90°C.
Maintain temperature between 125°C and 125°C. This temperature adjustment process is
After supercooling so that the polyester resin layer of the multilayer preform is maintained in a substantially non-crystalline state (amorphous state), using a heating mechanism known per se such as hot air, infrared heater, high frequency induction heating, etc.
This can be done by heating the multilayer preform to the above temperature, or by cooling or leaving it to cool in the injection mold or the mold until the temperature of the multilayer preform reaches the above temperature. You can do it even if you have to.

9 and 10 for explaining the stretch blow molding operation, a bottomed multilayer preform 10
Inserting the mandrel 101 into the mouth of 0,
The opening portion is held between a pair of split molds 102a and 102b. A stretching rod 103 that is vertically movable is provided coaxially with the mandrel 101.
03 and the mandrel 101 there is an annular passage 104 for fluid suction.

The tip 105 of the stretching rod 103 is connected to the preform 10
Place the stretching rod 1 on the inside of the bottom 106 of the
03 downward to perform tensile stretching in the axial direction, fluid is blown into the preform 100 through the passage 104, and the fluid pressure causes the preform to expand and stretch in the mold, thereby forming the container 1.
to form. The degree of stretching of the preform is sufficient to impart molecular orientation to at least the main resin layer, but for this purpose, the stretching ratio in the axial direction of the container should be 1.2 to 10 times, particularly 1.5 to 5 times. desirable.

(Preferred Embodiment of the Invention) Thermoplastic Polyester In the present invention, polyethylene terephthalate is preferably used as the thermoplastic polyester for the inner and outer layers. Copolyesters containing polyester units may be used. Copolymerization components for forming such a copolyester include isophthalic acid, p-β-oxyethoxybenzoic acid, naphthalene-2,6-dicarboxylic acid, and diphenoxyethane-
Dicarboxylic acid components such as 4,4'-dicarboxylic acid, 5-sodium sulfoneisophthalic acid, adipic acid, sebacic acid or their alkyl ester derivatives, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6- Glycol components such as hexylene glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, diethylene glycol, and triethylene glycol can be mentioned.

In terms of the mechanical properties of the vessel wall, the thermoplastic polyester used has an intrinsic viscosity (IV) as described below.
It is desirable that it be 0.5 or more, especially 0.6 or more. Furthermore, this polyester can also contain additives such as coloring agents such as pigments and dyes, ultraviolet absorbers, and antistatic agents.

Polyarylate or composition thereof The polyarylate used for the intermediate layer of the container opening and the closed bottom of the present invention is a thermoplastic resin obtained by condensing bisphenols and benzenedicarboxylic acids, and is a thermoplastic resin obtained by the following formula: In the formula, R represents an alkylidene group, especially a propylidene group.

It has a repeating unit represented by As the benzenedicarboxylic acid component, terephthalic acid, isophthalic acid, or a combination thereof is used, and bisphenol A is preferably used. A polyarylate particularly suitable for the purpose of the present invention has a dihydroxy component of bisphenol A and a benzenedicarboxylic acid component of terephthalic acid and isophthalic acid in a ratio of 70:30.
It is a polyarylate contained in the main chain at a weight ratio of 10:90 to 10:90. The polyarylate should also have sufficient molecular weight to form a film.

This polyarylate may be used alone, but
It may also be used in a blend with the thermoplastic resins mentioned above; in this case, these resins should be present in the form of a homogeneous mixture, and this homogeneous mixture can be achieved by homogeneously melt-kneading both resins. be exposed.

Gas Barrier Resin In the present invention, the gas barrier resin used in the intermediate layer of the container body is an ethylene-vinyl alcohol copolymer having a vinyl alcohol content of 40 to 85 mol%, particularly 50 to 80 mol%. It is important to use That is, the ethylene-vinyl alcohol copolymer is one of the resins with the best gas barrier properties, and its gas barrier properties and thermoformability depend on the vinyl alcohol unit content.
When the vinyl alcohol content is less than 40 mol%, the permeability to oxygen and carbon dioxide gas is greater than when it is within the above range, and it is not suitable for the purpose of the present invention, which is to improve gas barrier properties. figure,
On the other hand, if this content exceeds 85 mol %, the permeability to water vapor increases and the melt moldability decreases, which is not suitable for the purpose of the present invention.

Ethylene-vinyl alcohol copolymer is obtained by saponifying a copolymer of ethylene and a vinyl ester such as vinyl acetate so that the degree of saponification is 96% or more, especially 99% or more. In addition to the above-mentioned components, this copolymer may contain up to 3 mol% of oxygen atoms such as propylene, butylene-1, isobutylene, etc. within a range that does not impair the barrier properties to oxygen, carbon dioxide, etc. The above olefin may be contained as a comonomer component.

The molecular weight of the ethylene-vinyl alcohol copolymer is not particularly limited as long as it has a molecular weight sufficient to form a film, but it is generally used in a solvent containing 85% by weight of phenol and 15% by weight of water at a temperature of 30°C. It is preferable that the intrinsic viscosity (IV) is in the range of 0.07 to 0.17/g.

In another embodiment of the invention, a xylylene group-containing polyamide is used as the gas barrier resin for the intermediate layer. What is xylylene group-containing polyamide?
A polyamide containing m-xylylene diamine and/or p-xylylene diamine as a diamine component, more specifically 35 mol% of the diamine component.
Above, especially 50 mol% or more is m-xylylene and/or
or p-xylylene diamine, in which the dibasic acid component is an aliphatic dicarboxylic acid and/or an aromatic dicarboxylic acid, optionally containing up to 25 mol%, especially up to 20 mol% of ω-amino acid per total amide repeating unit. Contains carboxylic acid units.

Diamine components other than xylylene diamine include aliphatic diamines such as hexamethylene diamine, alicyclic diamines such as piperazine, and examples of aliphatic dicarboxylic acids include:
Examples of the aromatic dicarboxylic acids include adipic acid, sebacic acid, and suberic acid, and examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid. Further, examples of the ω-aminocarboxylic acid component include ε-caprolactam, amoheptanoic acid, aminooctanoic acid, and the like. Examples of xylylene group-containing polyamides include, but are not limited to, polymethaxylylene adipamide, polymethaxylylene sebacamide, polymethaxylylene sveramide, m-xylylene/p-xylylene adipamide copolymer, These include m-xylylene adipamide/isophthalamide copolymer, m-xylylene adipamide/thiophthalamide/ε-aminocaproic acid copolymer, and the like. The xylylene group-containing polyamide used is 96% by weight sulfuric acid and 1g/
0.4 to 0.4 when measured at a concentration of 100ml and a temperature of 25℃
It is desirable to have a relative viscosity (ηrel) of 4.5.
The gas barrier resins for the intermediate layer exemplified above can be used alone or in the form of a mixture of two or more. Furthermore, in order to improve the adhesion to the inner and outer polyester layers, the intermediate layer can be injected by supplying a dry blend or melt blend with the adhesive resin to an injection machine for the intermediate layer. Suitable examples of adhesive resins include aliphatic polyamide resins,
In particular, copolyamides such as nylon 6/nylon 6,6 copolymer. The adhesive resin can be used in an amount of 1 to 100 parts by weight, particularly 5 to 50 parts by weight, per 100 parts by weight of the gas barrier resin.

(Example) The invention is illustrated in the following examples.

Example Intrinsic viscosity 0.9 for inner layer injection machine and outer layer injection machine
Polyethylene terephthalate (PET) was supplied to the first intermediate layer injection machine as polyarylate, terephthalic acid and isophthalic acid in a weight ratio of 50:50 as the benzene dicarboxylic component, and bisphenol A as the dihydroxy component. Polymethaxylylene diapamide (PMA) is supplied as a gas barrier resin to the second intermediate layer injection machine.

At the initial stage of injection, a part of molten PET is injected into the cavity from the interior injection machine, then molten PET is simultaneously injected from the inner layer injection machine and outer layer injection machine, and molten PAR is simultaneously injected from the first intermediate layer injection machine. After finishing the part corresponding to the container mouth, stop all the injection machines, and then inject molten PMR from the second intermediate layer injection machine.
This molten PMR injects the previously injected molten PMR.
When PAR is reached, molten PET is injected again from the inner layer injection machine and the outer layer injection machine. Then,
When the bottom of the container is reached, all the injection machines are stopped, and then molten PAR is injected from the first middle layer injection machine, and at the same time, molten PET is again injected from the inner layer injection machine and the outer layer injection machine. eject. At the final stage of injection, molten PET was injected only from the outer layer injection machine to mold a multilayer preform of 3 types and 3 layers with a wall thickness of 5 mm.

This multilayer preform is heated to approximately 100°C and biaxially stretched blow molded to double the length and triple the width to create an inner volume.
I got a bottle of 1000c.c.

Fill this container with 2.5 volumes of a liquid containing carbon dioxide and immediately seal it. This bottle at 75℃
The container was immersed in hot water for 15 minutes and the change in internal volume was measured. There was almost no change in volume, and there was no deformation or damage to the container mouth or closed bottom, and the cap could be opened easily. Ta.

Furthermore, the thickness ratio of the inner layer: middle layer: outer layer of this bottle is 4.5:0.9:4.6 at the shoulder and 4.5:1:4.5 at the body.
The ratio was 4.4:0.8:4.8 at the bottom, and the position and thickness ratio of the intermediate layer were almost uniform in each part of the bottle.

Comparative Example According to the conventional molding method disclosed in JP-A No. 51-2773, a part of the molten PET is injected from the injection machine for the inner and outer layers at the initial stage of injection, and then the molten PET is injected from the injection machine for the inner and outer layers. At the same time, molten PMA was injected from the injection machine for the middle layer, and at the end of the injection, molten PET was injected from the injection machine for the inner and outer layers to create a wall thickness of 5 mm.
Two types of three-layer multilayer preforms were molded.

Furthermore, using this preform, an internal volume of 1000 c.c. was formed in the same manner as in the example.

When this was subjected to the same test as in the example, the container opening was significantly deformed and the volume expanded by 10%. Additionally, when the cap was opened, the opening of the container was damaged.

The thickness ratio of this bottle's inner layer: middle layer: outer layer is
3.4:0.9:5.7 at the shoulders 2.7:2.3:5 at the bottom
The ratio was 1.6:0.1:8.3, and the position and thickness ratio of the intermediate layer were non-uniform in each part of the bottle.

(Effects of the Invention) As is clear from the above description, in the container manufactured according to the present invention, the intermediate layer is uniformly present in each part of the container, and the thickness of the inner surface layer, the intermediate layer, and the outer surface layer is The ratio is almost constant in all parts of the container, and the intermediate layer of gas barrier resin is completely encapsulated by the polyethylene terephthalate on both the inner and outer surface layers, and the polyarylate at the ends is also completely encapsulated. , peeling between each layer is less likely to occur, and the flavor properties of the contents due to the gas barrier resin are not lost. In addition, deterioration of the gas barrier property of the gas barrier resin due to humidity is suppressed. Furthermore, by using polyarylate in the intermediate layer of the container opening and closed bottom, it is possible to strengthen the portions that are inherently poorly oriented and have poor deformation resistance and impact resistance.

Since the container according to the present invention has the above-mentioned excellent properties, it can be used as a container for various contents, especially a lightweight container that blocks the permeation of carbon dioxide gas or aroma components, and a lightweight container that requires hot water sterilization for fruit juice drinks and the like. It is useful, has significantly less carbonation loss than containers known for containers for beer, cola, cider, carbonated fruit juice drinks, etc., and
It has the advantage of being less prone to damage during transportation and handling, and preventing volumetric expansion due to changes in the mouth of the container, etc., due to hot water sterilization.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a blow-molded container of the present invention, FIG. 2 is an enlarged cross-sectional view of the mouth of the container of the present invention, and FIG. 3 is an enlarged view of the closed bottom of the container of the present invention. 4 is a diagram conceptually showing a simplified cross-sectional structure of a multilayer die used in the method of the present invention, and FIG. 5 is a diagram schematically showing the arrangement of the equipment used to implement the method of the present invention. 6 to 8.
The figure is a diagram for explaining the injection method of the present invention, and FIGS. 9 and 10 are diagrams for explaining the blow molding of the present invention. DESCRIPTION OF SYMBOLS 1... Blow molded container, 2... Mouth part, 3... Closed bottom part, 6... Thermoplastic polyester, 7... Polyarylate or its composition, 8... Gas barrier resin, 9... Multilayer die, 10... Solid channel for inner surface layer polyester, 11... Outer annular channel for outer surface layer polyester, 12... Inner annular channel for polyarylate and gas barrier resin, 14... Injection machine for inner layer polyester , 15... Injection machine for outer layer polyester, 16... Injection machine for middle layer polyarylate, 17... Injection machine for middle layer gas barrier resin, 100... Bottomed multilayer preform, 101
...Mandrel, 103...Stretching rod.

Claims (1)

[Scope of Claims] 1. A stretch-blown polyester container manufactured by stretch-blowing a polyester preform and having a thick-walled mouth, a biaxially stretched thin-walled body, and a closed bottom, the container as a whole comprising: At least the inner and outer surfaces are formed of polyethylene terephthalate, the mouth is formed of inner and outer layers of polyethylene terephthalate and an intermediate layer of polyarylate or a composition thereof, and the body has gas barrier properties with the inner and outer layers of polyethylene terephthalate. A container characterized by being formed with an intermediate layer of thermoplastic resin. 2. The container according to claim 1, wherein the closed bottom is formed of inner and outer layers of polyethylene terephthalate and an intermediate layer of polyarylate or a composition thereof. 3 In a method for manufacturing a stretch-blown polyester container, which involves manufacturing a preform mainly made of polyester by injection molding, and stretch-blowing this preform in a mold at a temperature that allows stretching, an inner layer is formed in a shape corresponding to the opening of the container. A solid stream of polyethylene terephthalate corresponding to the layer, an outer annular stream of polyethylene terephthalate corresponding to the outer layer, and an inner annular stream of polyarylate or its composition corresponding to the intermediate layer are co-injected in translation into an injection mold, and a container is formed. Corresponding to the body, polyethylene terephthalate corresponding to the inner layer is placed in a solid flow, polyethylene terephthalate corresponding to the outer layer is placed in an outer annular flow, and gas barrier thermoplastic resin is placed in an inner annular flow corresponding to the middle layer in an injection mold. A method for producing a stretch-blown polyester container characterized by simultaneous co-injection. 4. Injection mold with polyethylene terephthalate corresponding to the inner layer as a solid flow, polyethylene terephthalate corresponding to the outer layer as an outer annular flow, and polyarylate or its composition corresponding to an intermediate layer as an inner annular flow, corresponding to the bottom of the container. 4. A method for producing a stretch-blown polyester container according to claim 3, wherein the container is co-injected in a parallel manner.