JPH0242064B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multilayer stretched polyester bottle and a method for manufacturing the same, and more particularly, the present invention relates to a multilayer stretched polyester bottle and a method for manufacturing the same. The present invention relates to a method for producing a bottle whose molecules are effectively biaxially oriented by stretching and which has improved transparency and gas barrier properties.

Molding of stretched polyester bottles is common today, and the resulting molded containers are suitable for containers of liquid products such as liquid detergents, shampoos, cosmetics, soy sauces, sauces, etc. due to their excellent transparency and suitable gas barrier properties. In addition, in recent years, it has come to be widely used in containers for carbonated drinks such as beer, cola, and cider, as well as soft drinks such as fruit juice and mineral water.

However, since stretched polyester bottles are also made of plastic, gas permeability can be considered to be zero for completely sealed items such as glass bottles and metal cans. It has a slight permeability to carbon dioxide, which makes it inferior to cans and glass bottles in terms of food filling and preservation, and causes loss of carbon dioxide gas, especially in the case of carbonated beverages, and in beer, cola, cider, etc. It has clear storage period limits.

As a method for improving the gas barrier properties of stretched polyester bottles, improvement by applying polyvinylidene chloride resin to stretched polyester bottles has already been put into practical use. For this reason, there is no point in laminating or coating with a gas barrier resin that is inferior to polyester, and a gas barrier resin that is superior to polyester must be targeted. Therefore, thermoplastic resins such as vinylidene chloride resins, acrylonitrile resins, and vinylidene alcohol resins are candidates for gas barrier resins, but in any case, the properties and processability of each resin must be selected in relation to

In addition to the above-mentioned gas barrier problem, stretched polyester bottles have the problem of having to perform stretch blowing while suppressing crystallization of the polyester.

Generally, biaxially oriented polyester bottles are manufactured by injection molding a preform, which is a primary polyester product (intermediate product), or by preforming a pipe or tube formed by extrusion into a bottomed preform. However, polyethylene terephthalate (PET), which is widely used among polyesters, has a relatively fast crystallization rate between 130°C and 220°C, depending on its intrinsic viscosity (molecular weight), so it is difficult to use when molding preforms. After molding the specified shape in a mold or pipe water cooling tank, it is cooled as quickly as possible, and the resin temperature in all parts of the molded product is rapidly cooled to a temperature of 110℃ to 120℃ or less, so that it does not become supercooled. must not. if,
For example, if a part of a molded product remains at a high temperature without being rapidly cooled, that part will crystallize, becoming hazy or, in extreme cases, turning white, making stretch blowing impossible. Will it be?
Even if it can be blown, it becomes hazy and frosted glass-like, making it impossible to obtain a transparent container.

Therefore, in the injection molding of polyethylene terephthalate preforms and the molding of pipes, cooling methods as efficient as possible are used for cooling the mold and cooling the pipe with water.

However, if the thickness of the preform wall exceeds the limit, the resin in the mold cavity, core, and parts of the pipe that come in contact with cooling water will be rapidly cooled and become supercooled, becoming transparent. Due to the poor thermal conductivity of polyethylene terephthalate, the resin located far from the cooling wall is cooled slowly and is maintained at a high temperature, and crystallization progresses after a certain elapsed time.

This cooling delay is particularly important in the case of preforms and pipes that are multi-layered and include a gas barrier layer such as an ethylene-vinyl alcohol copolymer as an intermediate layer, unlike preforms and pipes made of normal single-layer PET. The problem arises that crystallization is likely to occur.

As a result of many experiments, the inventors found that when forming a multilayer pipe of polyethylene terephthalate and ethylene-vinyl alcohol copolymer, the ethylene-vinyl alcohol copolymer in the middle layer not only has gas barrier properties but also Among them, it was discovered that it acts as a so-called heat insulating layer and prevents the cooling of the resin on the inner layer side than the intermediate layer. In other words, in the cross section of a pipe with a certain thickness, the outer layer of polyethylene terephthalate is cooled by water cooling and becomes transparent, but the inner layer of polyethylene terephthalate located inside the middle layer, which is an ethylene vinyl alcohol copolymer, It is recognized that crystallization progresses and transparency is hindered.

Furthermore, in the method of manufacturing a multilayer pipe by coextrusion and molding a preform with a bottom from this pipe, the laminated plastic is extruded from a die at the tip of the extruder into water sized to a constant inner and outer diameter thickness, and is cooled. However, in this case, unless special measures are taken, cooling of the pipe during solidification is mainly done by water cooling from the outside, making it difficult to cool the inner wall of the pipe.

Therefore, there is no problem with thin single-layer pipes, but
When a thick multilayer pipe is used, the inner wall is maintained at a high temperature due to the poor heat conduction of the polyester and the intermediate layer, causing crystallization to progress and the pipe to become opaque.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a multilayer polyester bottle and a method for manufacturing the same, which eliminates the above-mentioned drawbacks.

Another object of the present invention is to provide a multilayer polyester bottle having a gas barrier intermediate layer made of an ethylene vinyl alcohol copolymer, which eliminates the reduction in transparency and molecular orientation caused by crystallization of the inner layer. and a method for producing the same.

Still another object of the present invention is to provide a multilayer polyester bottle that has excellent barrier properties against gases such as oxygen, transparency, impact resistance, rigidity, pressure resistance, etc., and a method for producing the same.

Still another object of the present invention is to provide a method for producing a multilayer polyester bottle that provides excellent stretch blowing workability.

According to the present invention, the multilayer stretched polyester has a neck part having an opening at the upper end and a fitting part or a threaded part on the outer periphery, a closed bottom part, and a body part whose molecules are biaxially oriented by stretch blowing. A bottle comprising an outer layer made of polyethylene terephthalate, a gas barrier middle layer made of an ethylene-vinyl alcohol copolymer having an ethylene content of 50 mol% or less, and a copolyester having a lower crystallization rate than polyethylene terephthalate. A bottle is provided, characterized in that it has an inner layer consisting of.

According to the present invention, the present invention further includes an outer layer made of polyethylene terephthalate, a gas barrier intermediate layer made of an ethylene-vinyl alcohol copolymer having an ethylene content of 50 mol% or less, and an inner layer made of a copolyester having a lower crystallization rate than polyethylene terephthalate. A pipe or tube is formed by co-extrusion, the pipe or tube is cut to an appropriate length, one end of the pipe or tube is fused and closed to form the bottom, and the other end is formed into the top. The preformed product obtained by molding into a mouth and neck having a fitting part or a threaded part on the opening and the outer periphery.
A method for producing a multilayer stretched polyester bottle is provided, which comprises preheating the bottle to a temperature appropriate for stretching from 85 to 120°C, and performing biaxial stretching blow molding in the axial and circumferential directions in a blow molding mold.

The invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1 showing a multilayer polyester bottle according to the present invention, this bottle 1 has an opening 2 at the upper end and has a screw 3, a support ring 4, and other engaging parts, threaded parts, and locking parts around the lid. Cervical region 5 with
and a torso 7 that is connected to the neck 5 via the shoulder 6.
and a closed bottom. The body 7 of this bottle is molecularly oriented in two axial directions, that is, in the axial direction of the bottle and in the circumferential direction of the bottle, by stretch blow molding.

As shown in the enlarged cross section, this bottle 1 has an outer layer 9 made of polyethylene terephthalate and an inner layer 10 made of a copolyester whose crystallization rate is lower than that of polyethylene terephthalate.
and an intermediate layer 1 made of an ethylene-vinyl alcohol copolymer having an ethylene content of 50 mol% or less, interposed between the layers,
Adhesive resin layers 12a and 12b are provided between the intermediate layer 11 and the inner and outer layers 9 and 10, if necessary.

As already mentioned, the present invention aims to prevent the disadvantages in heat transfer that occur when an ethylene-vinyl alcohol copolymer, which has excellent gas barrier properties, is used as an intermediate layer in a multilayer polyester bottle. By replacing the conventional polyethylene terephthalate (PET) with copolyester, which has a lower crystallization rate than PET, as the inner layer 10, crystallization of the inner layer resin that occurs during the molding operation is prevented as much as possible, and the resin In addition to improving the workability of stretching the layer, it also improves the transparency of the bottle.
Moreover, various physical properties due to stretching orientation are also improved.

As the polyethylene terephthalate, any polyethylene terephthalate known per se may be used, as long as it has a molecular weight sufficient to form a film, and polyesters with an intrinsic viscosity of 0.8 or more, particularly 1.0 or more are preferred. used for.

As the copolyester forming the inner layer 10,
A copolyester containing ester units mainly composed of ethylene terephthalate units and in which at least one of an acid component and an alcohol component is an acid component other than terephthalic acid or an alcohol component other than ethylene glycol is used. This copolyester has the advantage that it can be stretch blow molded under the same conditions as the PET that makes up the outer layer, and the inner layer itself cannot be given biaxial molecular orientation, as it is mainly composed of polyethylene terephthalate units. and having ester units other than ethylene terephthalate, PET
It offers the advantage of a lower crystallization rate compared to .

That is, in the present invention, the reason why polyester is used separately for the outer layer and the inner layer is that the outer layer of polyethylene terephthalate is cooled quickly by external cooling as described above, and the resin layer is rapidly cooled. Even if the copolyester is cooled slowly, crystallization is suppressed and transparency is maintained. This is because transparency is maintained.

In this copolyester, acid components other than terephthalic acid include isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, 2,2
-Bis(4-carboxyphenyl)propane, bis(4-carboxyphenyl)methane, cyclohexanedicarboxylic acid (hexahydroterephthalic acid, hexahydroisophthalic acid), adipic acid,
Sebacic acid, succinic acid, dodecanedicarboxylic acid, etc. can be mentioned, and alcohol components other than ethylene glycol include propylene glycol, butanediol, neopentyl glycol,
Examples include hexanediol, glycerol, diethylene glycol, triethylene glycol, tetraethylene glycol, dibutylene glycol, and tributylene glycol. Of course, these acid components and/or alcohol components can be used alone or in combination of two or more.

Examples of suitable copolyesters include, but are not limited to:

Polyethylene terephthalate/isophthalate, polyethylene terephthalate/adipate, polyethylene/butylene terephthalate, polyethylene/butylene terephthalate/isophthalate, polyethylene/neopentylene terephthalate, polyethylene/neopentylene terephthalate/isophthalate.

In the present invention, the copolyester used is
85 to 96 mol% of ethylene terephthalate units,
In particular, it is desirable that the content be in the range of 90 to 94 mol %, with the remaining amount containing other ester units. Of course, this copolyester should also have a sufficient molecular weight to form a film.

As already mentioned, the present invention aims to improve the gas barrier properties of stretched polyester bottles, and among vinyl alcohol resins, ethylene-vinyl alcohol copolymers, particularly ethylene components of 50 mol% or less, are used. A copolymer of As is already known, polyvinyl alcohol is not thermoplastic unless special processing methods are used, but in ethylene-vinyl alcohol copolymers, as the ethylene content increases, the melting point decreases and the thermoplasticity increases. . Since the ethylene-vinyl alcohol copolymer is stretch blown together with the polyester resin as described below, it is normally assumed that the melting point is as low as possible and the temperature at which it can be stretched is as low as possible, but here, the melting point and stretching temperature are We chose high-quality ethylene-vinyl alcohol copolymerization. The first reason is that when the ethylene component exceeds 50 mol%, the melting point is low and the temperature at which it can be stretched is also low, which is convenient for co-stretching with the polyester resin layer, but as the ethylene component increases, the Since the gas barrier property decreases, it is not worthwhile to make the polyester resin multi-layered.The second reason is that even if the ethylene-vinyl alcohol copolymer is low in ethylene content and high in vinyl alcohol content, According to the method of the invention, as will be detailed later, in the form of a multilayer structure with polyester resin,
It has been discovered that the ethylene-vinyl alcohol copolymer layer can be stretched even at the appropriate stretching temperature for polyester resin, so the ethylene-vinyl alcohol copolymer used for multilayering of the present invention has an ethylene content of 50 mol% or less. In other words, we selected a material with a high vinyl alcohol content.

In the present invention, the ethylene-vinyl alcohol copolymer used is a copolymer obtained by saponifying a copolymer of ethylene and a vinyl ester such as vinyl acetate. , with an ethylene content of 15 to 50 mol%, especially 25 to 45 mol%, and a saponification degree of 96.
% or more are advantageously used. The molecular weight of this copolymer may be any as long as it has film-forming ability.

Further, if necessary, any known adhesive can be used to enhance the adhesiveness between the polyester layer and the ethylene-vinyl alcohol copolymer layer. Copolyester adhesives, polyester-ether adhesives, epoxy-modified thermoplastic resins, acid-modified thermoplastic resins, etc. are used for this purpose.

The thickness ratio of the polyester layer and the ethylene-vinyl alcohol copolymer layer is preferably in the range of 2:1 to 30:1, especially 4:1 to 15:1. and the inner copolyester layer have a thickness ratio of 1:1 to 5:
1, particularly preferably in the range of 2:1 to 3:1. In particular, it should be noted that the present invention also includes an embodiment in which the outer layer is made thicker and the inner layer is made thinner to further promote cooling of the inner layer. If an adhesive is used, the thickness ratio of the polyester layer to the adhesive layer is preferably between 5:1 and 100:1, particularly between 10:1 and 50:1.

The present invention is advantageously applied to a method in which the above-described multilayer structure is coextruded into a pipe, formed into a bottomed preform, and then stretch-blown.

Traditionally, stretch-blow molding of plastics such as polyester involves injecting the plastic to form a bottomed balisong (briform) and blow-stretching it while axially stretching it with a stretching rod, or extruding the plastic into a pipe shape. Various methods are known, such as a method in which the material is held between a pair of clamps and stretched in the axial direction, and then a fluid is blown into the film to blow-stretch it.

However, it has been found that these methods, when applied to multilayer barisons of polyester and ethylene-vinyl alcohol copolymers, have certain drawbacks in terms of stretchability and interlayer adhesion.

First, as already pointed out, polyester
When it exceeds a certain temperature, for example 140℃,
It easily crystallizes, making it difficult to stretch, and tends to whiten and make the container itself opaque. In order to produce a multilayer parison by injection, it is necessary to injection mold polyester, then injection mold the ethylene vinyl alcohol copolymer onto the single-stage molded polyester, and then injection mold the polyester again. Since the temperature of the one-stage molded product must be kept much lower than the above temperature, the degree of thermal adhesion between the two resins at the interface becomes extremely incomplete, resulting in delamination or delamination during stretch blow molding. There is a tendency for the ethylene-vinyl alcohol copolymer layer to break at this peeled portion.

Second, ethylene-vinyl alcohol copolymers have a problem in that they are significantly lacking in stretchability, especially biaxial stretchability, at the appropriate stretching temperature for polyester. That is, polyester and ethylene
When a multilayer pipe coextruded with vinyl alcohol copolymer is held in clamps and stretched in the axial direction, and then blow stretched, the ethylene-vinyl alcohol copolymer layer has many tears or potential cracks in the axial direction. There is a tendency for this to occur. This is because axial stretching causes a phenomenon similar to fibrillation in the ethylene-vinyl alcohol copolymer layer.
This seems to be because cracks, etc. occur during the next stretching operation.

In a preferred embodiment of the present invention, first, polyester and ethylene-vinyl alcohol copolymer are
The first feature is coextrusion into a pipe or tube.

That is, this coextrusion is performed by combining molten polyester and molten ethylene-vinyl alcohol copolymer in a die and extruding it through a ring-shaped orifice, but these multiple types of resins are both in a molten state. Because of the time-long contact, the resins mix well at the interface between the two, and the thermal adhesion between the two is stronger than in the case of multilayer injection molding. This is exactly the same even when an adhesive resin is interposed between the polyester and the ethylene-vinyl alcohol copolymer.

The second feature is that this coextruded multilayer pipe or tube is cut to a certain length, and one end thereof is fused and closed to form a bottom part. In other words, by using this preform with a bottom, it is possible to perform blow stretching simultaneously or almost simultaneously with axial stretching while pressing a stretching rod against the preheated preform, which is possible in the case of sequential stretching. This eliminates the occurrence of cracks and potential cracks in the ethylene-vinyl alcohol copolymer layer.

Figure 2 shows a multilayer pipe 13 which is particularly suitable for the purposes of the invention, comprising an inner layer 10 of copolyester, an outer layer 9 of PET, and an intermediate gas barrier layer of ethylene-vinyl alcohol copolymer. 11 and the adhesive layer 1 interposed between them
It consists of 2a and 12b.

It has already been pointed out that it is important to manufacture pipes and tubes by coextrusion, but it is important to cool the extruded pipe by immersing it in water to prevent crystallization of the polyester. It is.

After cutting this pipe to a certain size, one end of the pipe is heated and melted, and then pressed with a male and female mold having a cavity and protrusion corresponding to an arbitrary bottom shape, such as a semicircular shape, as shown in Fig. 3. A bottom portion 14 is formed as shown.

Next, the other end of this pipe 13 is also heated and subjected to pressing, stretching, blow molding, etc. in a desired mold, and as shown in FIG. Netsukuring (Support Ring) 4
It is formed into a preform 15 having a fitting part, a screwing part, and a locking part with a lid such as the above.

The order of forming these preforms does not matter, and they can be performed in the above order or in the reverse order, or they may be performed simultaneously.

The method described above has the characteristic that no excess resin is generated when a preform is obtained from a multilayer pipe or tube.

Next, in the third step, the preform is preheated using hot air, an infrared heater, high frequency dielectric heating, etc. to a temperature appropriate for stretching the multilayer preform. In this case, the temperature range is 85 DEG to 120 DEG C., preferably 95 DEG to 110 DEG C., which is the stretching temperature of the polyester resin.

In FIGS. 5 and 6 for explaining the stretch blow molding operation, a mandrel 16 is inserted into the mouth of a preform 15, and the mouth is held between a pair of split molds 17a and 17b. mandrel 1
A vertically movable stretching rod 18 is provided coaxially with the mandrel 16, and between this stretching rod 18 and the mandrel 16 there is an annular passage 19 for fluid injection.

In the present invention, the tip 20 of the stretching rod 8 is applied to the inside of the bottom 14 of the preform 15,
By moving the stretching rod 18 downward, the preform is stretched in the axial direction, and at the same time, fluid is blown into the preform 15 through the passage 19, and the preform is expanded and stretched in the circumferential direction by the fluid pressure.

According to the present invention, since the inner layer 10 is made of a copolyester which has a lower crystallization rate than the PET outer layer, the crystallization of the inner layer resin, which cools slowly, is completely suppressed throughout the entire bottle manufacturing process, resulting in a significantly superior product. Transparency and stretch orientation performance are simultaneously achieved.

Thus, in addition to excellent transparency, this multilayer stretched polyester bottle has gas barrier properties that are superior to other plastic bottles and even higher than that of a single polyester (stretched PET) bottle. Adjustable and pressure resistant, the bottle is extremely easy to fill and store carbonated beverages, i.e. beer, cola and cider, and the container is hygienic and can be used for disposal and incineration of used containers. However, the gas generated by the bottle is almost exclusively carbon dioxide and water, and even if no harmful gas is generated, it is easily incinerated, and while it has transparency, gas barrier properties, and pressure resistance comparable to glass bottles, it is lightweight and durable. An ideal container with breakability is provided.

The present invention has been mainly described with respect to a tube manufacturing method using coextrusion and a manufacturing method that employs a bottomed preform molding method, but the effect of suppressing crystallization even if cooling of the inner layer resin is delayed is
It should be understood that exactly the same effect can be achieved when employing a bottomed preform forming means by injection molding.

The invention is illustrated by the following example.

Example 1 An extruder for the outer layer and an extruder for the inner layer that have a built-in full-flight screw with a diameter of 65 mm and an effective length of 1430 mm, an extruder for the middle layer that has a built-in full-flight screw with a diameter of 50 mm and an effective length of 1100 mm. Using a machine and an extruder for the adhesive layer, a ring-shaped die for 5 layers,
The outer layer is polyethylene terephthalate with an intrinsic viscosity of 1.0, the inner layer is an ethylene terephthalate copolymer with an isophthalic acid content of 8 mol% (intrinsic viscosity 1.1), the middle layer is an ethylene-vinyl alcohol copolymer with a vinyl alcohol content of 70 mol%, and The adhesive layer interposed between the outer layer, the inner layer, and the intermediate layer is a polyester-ether block copolymer, and the thickness ratio of each layer is 100:5:15:5 from the outer layer.
40 to the inner layer, outer diameter 30.0mm, thickness 3.8mm,
The pipe was co-extruded using four extruders and extruded from a multilayer die into a water-cooled cooling tank to obtain a multilayer pipe with four types and five layers. The lower end of the obtained transparent pipe is fused and closed to form a semicircular sphere, the upper end is formed into a neck and neck part having a threaded part, and the obtained preform is preheated to 98 ° C. Biaxial stretch blow molding was performed in a blow mold to obtain a multilayer stretched polyester bottle.

The obtained bottle body has a haze degree of 0 to 12 and a height of 120 cm.
The oxygen permeability of this bottle is 37°C and 100% RH inside the bottle, without being damaged by dropping it on concrete.
Under the condition of external 20% RH, the oxygen permeability of a single polyethylene terephthalate bottle with the same weight and shape and 1.7cc/m ² 24H・atm is 9.8cc/m ²・
24H·1atm, and the oxygen permeability of the bottle of the present invention was 1/5 that of a bottle made of PET alone.

Example 2 Using the same equipment as in Example 1, the outer layer had an intrinsic viscosity of
0.9 polyethylene terephthalate, the inner layer is a polyethylene terephthalate copolymer (intrinsic viscosity 1.1) with an isophthalic acid content of 8 mol%, the middle layer is an ethylene-vinyl alcohol copolymer with a vinyl alcohol content of 70 mol%, and the adhesive layer is A multilayer pipe of 4 types and 5 layers made of maleic anhydride-grafted modified high-density polyethylene containing 10,000 ppm of epoxidized octyl olefinate is extruded into water through a die and cooled. The outside diameter of this pipe is 30mm and the inside diameter is 22mm
mm, and the thickness of each layer is 1.4 mm for the inner layer and 1.4 mm for the outer layer.
2.0mm, adhesive layer is 0.05mm each and middle layer is
0.5mm, and this pipe has a certain dimension (length 129
mm, weighing 55 g)) and cut one end of the pipe into approx.
℃ to close the bottom of the semicircle and close the other end.
A preform with a total height of 148 mm was obtained by heating at 150°C to promote neck crystallization and molding the threaded part and neck ring.

This preformed product was heated to 105°C, and in a blow mold, it was stretched in the vertical axis direction and then blown and stretched in the horizontal axis direction, almost simultaneously biaxially stretching blow molding to obtain an internal volume of 1550 c.c. A multilayer stretched bottle was obtained. The haze level of this bottle is 9, and the oxygen permeability is approximately 1.5cc/ ^m2 .
The temperature was 24H・atm (37℃), and there was no damage when dropped onto concrete from a height of 120cm, and no peeling occurred between the layers. Furthermore, since the neck of this bottle was considerably crystallized, the neck did not deform even when filled with liquid at 93°C and sealed.

Example 3 Using the same equipment as in Example 1, the outer layer had an intrinsic viscosity of
1.0 polyethylene terephthalate, the inner layer is an ethylene terephthalate copolymer in which part of the glycol component is 1,4-cyclohexanedimethanol, (trade name KodarPETG6 763) the middle layer is ethylene-vinyl alcohol with a vinyl alcohol content of 70 mol% The copolymer and the adhesive layer interposed between the outer and inner layers and the intermediate layer are maleic anhydride grafted polyethylene (maleic acid content 0.8% by weight).
A multilayer pipe of 4 types and 5 layers was extruded and cooled in water.

The outer diameter of this pipe is 22 mm, the inner diameter is 16 mm, and the thickness of each layer is 1.6 mm for the outer layer, 1.2 mm for the inner layer, and 0.2 mm for the middle layer. ) and cut one end of the pipe to approx.
The temperature was controlled to 230°C, the bottom of the semicircular sphere was closed, and in order to prevent neck crystallization, the other end was preheated to about 110°C to form a screw and a neck ring to obtain a preformed product.

This preformed product was heated to 100°C and then biaxially stretched and blow molded in both the vertical and horizontal directions at the same time, resulting in an inner volume of
A multilayer stretched bottle of 500 c.c. was obtained.

The haze level of this bottle is 8, and the oxygen permeability is 2.0.
cc/ ^m2・24H・atm (37℃), and no damage occurred when dropped from a height of 120cm onto concrete.

[Brief explanation of drawings]

Fig. 1 is a multilayer stretched bottle of the present invention, Fig. 2 is a sectional view of a multilayer pipe, Figs. 3 and 4 are sectional views of a preform with a bottom and a neck formed, and Figs. 5 and 6. The preformed product is held in a blow mold, and is a cross-sectional view before blow molding and a cross-sectional view after blow molding. Reference number 1 indicates a multilayer bottle, 9 indicates an outer layer, 10 indicates an inner layer, 11 indicates an intermediate layer, 13 indicates a multilayer pipe, and 15 indicates a preform.

Claims (1)

[Scope of Claims] 1. A multilayer stretched film having a neck part having an opening at the upper end and a fitting part or a threaded part on the outer periphery, a closed bottom part, and a body part whose molecules are oriented in biaxial directions by stretch blowing. A polyester bottle comprising an outer layer made of polyethylene terephthalate, a gas barrier middle layer made of an ethylene-vinyl alcohol copolymer having an ethylene content of 50 mol% or less, and a copolyester having a lower crystallization rate than polyethylene terephthalate. A bottle characterized in that it has an inner layer consisting of. 2 an outer layer consisting of polyethylene terephthalate;
A pipe or tube is formed by coextrusion, with a gas barrier intermediate layer made of an ethylene-vinyl alcohol copolymer with an ethylene content of 50 mol% or less, and an inner layer made of a copolyester with a lower crystallization rate than polyethylene terephthalate. , Cut the pipe or tube to an appropriate length, seal one end of the pipe or tube to form the bottom, and add an opening at the top of the other end and a fitting or threaded portion on the outer periphery. The resulting preformed product is preheated to a suitable stretching temperature of 85 to 120°C, and then biaxially stretched and blow molded in the axial and circumferential directions in a blow molding mold. Method for manufacturing stretched polyester bottles.