JPS6333242A - Oriented multilayer plastic vessel and manufacture thereof - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a stretched multilayer plastic container.
More particularly, it relates to stretched multilayer plastic containers that have a combination of excellent gas barrier properties, delamination resistance, and mechanical properties.

(Conventional technology) yj? IJ ethylene terephthalate has excellent moldability and is capable of biaxial molecular orientation, so it is particularly useful for lightweight plastic containers with excellent impact resistance, rigidity, gas barrier properties, light weight, and transparency. It has come to be widely used as a drinking pin. However, the gas permeability of this polyester bottle is still not negligible compared to glass bottles, and the shelf life of the bottle when filled with carbonated drinks such as cola is said to be about 3 months.

In order to improve the gas barrier properties of such stretched polyester containers, resins with excellent gas barrier properties, such as ethylene vinyl alcohol copolymer and polyamide, are used.
Containers using composite laminates have been proposed in which polyester is laminated, for example, a resin with excellent gas barrier properties is used as an intermediate layer, and polyester is laminated on both surfaces as surface layers.

(For example, JP-A-59-136253, JP-A-61
-60436).

(Problem to be solved by the invention) However, there is almost no thermal adhesion between the ethylene vinyl alcohol copolymer layer or polyamide layer and the polyester layer, and even if they are bonded using an adhesive, Even if the laminate exhibits good adhesion in an unstretched state, it has the disadvantage that it easily peels off at the adhesive interface when the laminate is stretched to impart molecular orientation.

For example, co-, ff IJ ester-based adhesives and co-polyamide-based adhesives that have been conventionally proposed for bonding polyester layers and polyamide layers all have the above-mentioned tendency, and are suitable as adhesives for stretched multilayer plastic containers. It is still not completely satisfactory.

Thermoplastic resin adhesives containing amide groups have been proposed for bonding the ester layer and the ethylene vinyl alcohol copolymer layer, but these are not necessarily fully satisfactory. do not have.

Therefore, the chileester layer is formed from a multilayer laminate with a resin layer having excellent properties, and even after stretching, it has excellent delamination resistance, especially blister resistance, and has gas barrier properties, impact resistance, and rigidity. Furthermore, there was a need to provide a stretched multilayer plastic container with excellent transparency.

(Structure of the Invention) According to the present invention, the inner and outer surface layers are made of polyester, the intermediate layer is made of a blend of ethylene-vinyl alcohol copolymer and polyamide, and the sulfone layer is provided between the surface layer and the intermediate layer. A stretched multilayer plastic container is provided comprising an acid-base containing copolyester layer.

Still according to the invention, inner and outer surface layers made of polyester, an intermediate layer made of a blend of ethylene-vinyl alcohol copolymer and polyamide, and a sulfonic acid group-containing layer provided between the surface layer and the intermediate layer are provided. A method for producing a stretched multilayer plastic container is provided, which comprises forming a multilayered sheet or preform made of polyester layers into a container shape under stretching conditions.

(Actions and Effects of the Invention) The present invention provides sulfonic acid group-containing compounds, t? A structure formed by laminating a polyester layer and a blend layer of ethylene-vinyl alcohol copolymer and polyamide using IJ ester as an adhesive layer may also cause delamination when subjected to stretch molding. This is based on the unexpected finding that it maintains excellent adhesive strength. With the present invention, ethylene-vinyl alcohol, which has extremely excellent gas barrier properties but was difficult to use due to its poor adhesion with polyester, can be combined with polyester and used as a gas barrier-providing material for polyester stretch-molded containers. This made it possible to put it into practical use.

Table 1 below shows that unstretched polyethylene terephthalate film (thickness: 400 μm) and ethylene-vinyl alcohol copolymer ( EVOH) (ethylene content: 31 moles) and an unstretched film (thickness: 100 μm) made from a blend of nylon 6/nylon 66 copolymer (blend ratio: EVOH:nylon = 6:4) were laminated together, and this lamination was performed. The adhesive strength of the film and the adhesive strength of a biaxially stretched film obtained by biaxially stretching this laminated film twice in the longitudinal direction and twice in the transverse direction are shown.

6-1 in Table 1) 1 Urethane adhesive 230g 15
g2 Copolyamide type) 320g 1
8g-*'5) 3 Copolynisal 290. ! i2
20.9*4) 4 Polyesteramide 650. ! i7
180g Note *1) In the case of urethane adhesive, peeling is due to cohesive failure of the adhesive *2) Nylon 6/nylon 66 copolymer (caprolactam concentration is 91 molar), and the adhesive strength is the adhesive strength between polyethylene terephthalate and the adhesive interface. Show that.

*3) As dibasic acids, terephthalic acid (20 moles), isophthalic acid (60 moles), cono-X phosphoric acid (20 moles)
, a copolyester with a glass transition temperature of 35°C using butylene glycol as the glycol, with an adhesive strength of EV
It shows the adhesive strength between OH/nylon and adhesive interface.

*4) N,N'-bis(p-carboxybenzoyl)hexamethylenediamine and hexane-1,6-diol are transesterified and then polycondensed, and the melting point is 2.
Adhesive strength with polyesteramide at 65°C indicates the adhesive strength between the nylon and adhesive interface.

*5) Adhesive strength of the sulfonic acid group-containing copolyester used in Example 1 described below of the present invention indicates the adhesive strength between the EVOH/nylon and adhesive interface.

*6) Cut the sample into a 15m wide rectangle and cut 100 pieces/
Shows the T-peel adhesive strength measured at a peel rate of min (
unit,! i'/15 run width).

According to the results in Table 1 above, the adhesives of samples 1 to 4 were:
Although they exhibit a high adhesive strength in the unstretched state, they all show a significant decrease in adhesive strength after stretching and forming, whereas the sulfonic acid group-containing copolyester (Sample 5) of the present invention exhibits a large adhesive strength in Samples 1 to 4. It is clear that the adhesive strength is greater than that even after stretching.

The sulfonic acid group-containing copolyester used in the present invention is
It has a chemical structural feature in that the main chain consists of repeating ester units and a sulfonic acid group is bonded to this main chain. For this reason, this adhesive not only bonds extremely strongly with polyethylene terephthalate, but also forms a strong chemical bond with the polyamide in the blend of sulfonate, ethylene-vinyl alcohol copolymer, and polyamide. It is estimated to be.

A blend of ethylene-vinyl alcohol copolymer and topolyamide is a polymer that requires stricter stretching conditions than polyester, but in the present invention, this blend is sandwiched between the inner and outer surface layers of polyethylene terephthalate. However, since the two are strongly bonded by a copolyester having a sulfonate group, stretch molding becomes possible, and it is thought that strong adhesive strength is maintained even after stretch molding.

According to the present invention, even after stretch molding, a strong adhesive strength is maintained between the polyester layer and the initial blend layer of ethylene-vinyl alcohol copolymer and polyamide, and as a result, the container is subjected to drop impact. This prevents delamination even when the material is filled with carbonated beverages, beer, etc., and also prevents blisters from forming at the joint between the polyester layer and the first layer of the blend. This problem is effectively solved.

Furthermore, a blend of ethylene-vinyl alcohol copolymer and polyamide with excellent gas barrier properties is provided in the middle layer, and the polyester layer is molecularly oriented by stretching, resulting in excellent gas barrier properties and resistance to glabella peeling. A multilayer plastic container with excellent durability, impact resistance, rigidity, and even transparency is provided.

(Description of Preferred Embodiments of the Invention) Adhesives As mentioned above, the sulfonic acid group-containing copolyester used in the present invention has a main chain skeleton composed of repeating ester units and a sulfonate group bonded to this main chain skeleton. means a copolyester consisting of Of course, this adhesive may consist of the above-mentioned copolyester alone, or may be a blend of the above-mentioned copolyester and a normal polyester containing no sulfonic acid groups. In the present invention, coyjP IJ ester is used in the above-mentioned meaning.

The concentration of sulfonate groups in the copolyester used in the invention is preferably present in the range from 1 to 520 mmol, especially from 5 to 30 mmol, per 100 g of adhesive. If this concentration is lower than the above range, the adhesion with the blend will be insufficient, while if it is higher than the above range, the adhesion with the polyester will be insufficient or the copolyester itself will not have sufficient thermal stability. There is a tendency for defects to occur in gender, etc.

As the sulfonate, alkali metal salts such as sodium salts, potassium salts, and lithium salts are suitable, but alkaline earth metal salts such as calcium salts and magnesium salts, and zinc salts are not particularly prohibited.

In order to incorporate a unit having a sulfonate group into the polyester skeleton, a component containing a sulfonate group may be used as part of the dibasic acid component and/or diol component for forming the polyester.

Generally, it is preferable to use a dibasic acid component containing a sulfonic acid group.

Suitable examples of such components include sodium 3,5-di(carboxy)benzenesulfonate, potassium 3,5-di(carboxy)benzenesulfonate, magnesium 3,5-di(carboxy)benzenesulfonate, and , functional derivatives thereof, such as esters with methyl alcohol, ethyl alcohol, ethylene glycol, etc.

Others include sodium sulfosuccinic acid, sodium sulfoterephthalic acid, 4-sodium sulfonaphthalene-2,
Examples include 7-dicarboxylic acids and lower alcohol esters thereof.

The dibasic acids constituting this copolyester include benzenedicarboxylic acids such as terephthalic acid and isophthalic acid,
other aromatic dicarboxylic acids such as naphthalenedicarboxylic acid; aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sepacic acid, dodecanedicarboxylic acid; dicarboxylic acids, etc., and diol components include aliphatic diols such as ethylene glycol, zoropylene glycol, butanediol, diethylene glycol, neopentyl glycol, and hexanediol; cyclohexanediol, xylylene glycol, and bisphenol A;
, cyclic glycols such as bisphenol F, and the like.

In the copolyester used in the present invention, terephthalic acid accounts for 50 or more moles of the total dibasic acid component, especially 85 mole or more of the total dibasic acid component, excluding those introduced as sulfonic acid metal base-containing units, and 50 moles or more,
Particularly preferred is one in which the mole fraction is ethylene glycol or more.

The copolyester used should have sufficient molecular weight to form a film.

Polyester 13 - The polyester used in the present invention usually contains 50 or more molar units of ethylene terephthalate, preferably 70 molar units or more.
It is a polyester obtained from an alkylene glycol having 2 to 4 carbon atoms and an aromatic dicarboxylic acid containing a molar coefficient or more. As the alkylene glycol, ethylene glycol is mainly used, but in addition to ethylene glycol, for example, 1,3-propanediol, 1.4
-Butanediol can be used in an amount that satisfies the above content of ethylene terephthalate structural units. Terephthalic acid is mainly used as the aromatic dicarboxylic acid, but in addition to terephthalic acid, for example, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, etc. may be used as long as the content of the ethylene terephthalate structural unit is satisfied. It can be used in the same amount. Among these, polyethylene terephthalate is particularly preferred for practical purposes.

The intrinsic viscosity [η] (value measured at 25°C in a phenol-tetrachloroethane mixed solvent (weight ratio 1/1)) of the polyester is usually 0.5 to 1.5 dllg, preferably 0.6 to 1.5 dllg. 2 dl/i, and the melting point is usually 210
from 265°C to 265°C, preferably from 220 to 260°C,
The glass transition temperature is usually 50 to 120°C, preferably 6
The temperature is 0 to 100°C.

The polyester may contain nucleating agents, inorganic fillers, lubricants, slip agents, anti-blocking agents, stabilizers,
Appropriate amounts of various additives such as antistatic agents, antifogging agents, and pigments may be blended.

The resin used as the intermediate layer in the present invention is a blend of ethylene-vinyl alcohol copolymer and polyamide.

As for the ethylene-vinyl alcohol copolymer, a copolymer having an ethylene component of 50 molar percentage or less is preferred in order to improve gas barrier properties. As is already known, polyvinyl alcohol is not thermoformable unless special processing methods are used, but in ethylene-vinyl alcohol copolymers, the melting point decreases and the thermoplasticity increases as the ethylene content increases. bring. Since the ethylene-vinyl alcohol copolymer is stretch-molded together with polyester resin as described below, it would normally be assumed that the melting point is low and the temperature at which it can be stretched is low, but here we will discuss the melting point and stretching temperature. An ethylene-vinyl alcohol copolymer is selected because of its high temperature. The first reason is that when the ethylene component exceeds 50 molar ratio, the melting point is low and the temperature at which stretching is possible is also low, which is convenient for co-stretching with the polyester resin layer, but when the ethylene component is large, There is no point in multilayering the polyester resin because the gas barrier properties will drop rapidly.The second reason is that it is an ethylene-vinyl alcohol copolymer with a low ethylene content and a high vinyl alcohol content. According to the present invention, as will be detailed later, it has been discovered that it is possible to stretch an ethylene-vinyl alcohol copolymer layer in the form of a multilayer structure with a polyester resin even at the appropriate stretching temperature for the polyester resin. Therefore, the ethylene-vinyl alcohol copolymer used for multilayering in the present invention was selected to have an ethylene component of 50 molar percentage or less, that is, a high vinyl alcohol content.

In the present invention, as the ethylene-vinyl alcohol copolymer, a copolymer obtained by saponifying a copolymer of ethylene and a vinyl ester such as vinyl acetate is used,
In consideration of molding workability and barrier properties, those having an ethylene content of 15 to 50 moles, particularly 25 to 45 moles, and a saponification degree of 96 moles or more are advantageously used. The molecular weight of this copolymer may be any as long as it has film-forming ability.

The spun polyamide is made of an aliphatic, aromatic, or araliphatic diamine and an aliphatic, aromatic dicarboxylic acid, or an aliphatic, aromatic, or araliphatic aminocaldic acid or a lactam thereof, or a mixture thereof. polyamides or copolyamides can be used.

Such polyamides are known per se and include oxygen,
From the viewpoint of gas barrier properties against carbon dioxide gas, etc., homopolyamides, copolyamides, or blends thereof in which the number of amide groups per 100 carbon atoms in the polyamide is in the range of 3 to 30, particularly 4 to 25. It is preferable to use a material.

Examples of suitable homopolyamides are: polycapramide (nylon 6) poly-ω-aminoheptanoic acid (nylon 7) poly-ω-
aminononanoic acid (nylon 9) polyundecaneamide (
Nylon 11) Polylaurinlactam (Nylon 12)
Polyethylene diamine adipamide (nylon 2,6) polytetramethylene adipamide (nylon 4,6) polyhexamethylene dodecamide (nylon 6.6) polyhexamethylene dodecamide (nylon 6.10) polyhexane Methylenedodecamide (nylon 6.12) polyoctametherene azo gumide (nylon 8,6)? These include lidecamethylene azide/matoramide (nylon 10.6), polydodecamethylene cepacamide (nylon 10.8), and the like.

Examples of suitable copolyamides include kaglolactam/laurinlactam copolymer, Kaguchi lactam/hexamethylene diammonium adipate copolymer, laurinlactam/hexamethylene diammonium adipate copolymer, hexamethylene diammonium adipate / hexamethylene diammonium sepacate copolymer, ethylene diammonium ano-to / hexamethylene diammonium adipate copolymer, caprolactam / hexamethylene diammonium adipate / hexamethylene.
Examples include soammonium sepacate copolymer.

These homopolyamides and copolyamides can also be used in the form of so-called blends, for example blends of polycaprolactam and 2-lihexamethyleneazinodimide, pre-caprolactam and caprolactam/hexamethylene diammonium anohate copolymer. Blends and the like may all be used for purposes of the present invention.

In addition, although it is slightly inferior in moldability compared to the above-mentioned aliphatic polyamide, it is disclosed in, for example, Japanese Patent Publication No. 50-1156, Japanese Patent Publication No. 5751-1982, Japanese Patent Publication No. 5753-1983, and Japanese Patent Publication No. 50-10196. , Japanese Patent Publication No. 50-29
Metaxylylene diamine, or mixed xylylene diamine containing varaxylylene/cyamine with a carbon number of 30 or less in the diamine, as described in Publication No. 697, etc., and a carbon number of 6 to 10.
α, ω-aliphatic radicals? An aromatic polyamide containing at least 70 molar units of a structural unit formed from phosphoric acid in its molecular chain can also be used.

Furthermore, metaxylylene diamine, or metaxylylene diamine and a mixed xylylene diamine containing 304 or less paraxylylene diamine in the diamine, and an aromatic dicarboxylic acid containing isophthalic acid at a molar ratio of 30 or more, preferably 40 or more. An aromatic polyamide containing at least 70 moles of structural units produced from the above in its molecular chain can also be used.

Furthermore, an aromatic polyamide containing metaphenylene diamine and/or haharaphenylene diamine and isophthalic acid in an amount of 30 or more, preferably 40 or more moles can also be used.

The molecular weight of these polyamides can be used without any particular restriction as long as it is within a range that generally improves film forming ability.

Ethylene-vinyl alcohol copolymer (Evot.

The blend ratio of EVOH and polyamide is preferably 7:3 to 2:8 by weight.

The method for blending the ethylene-vinyl alcohol copolymer with Topho IJ amide is a method known per se that is applied to blending two or more polymers, for example, blending powders of each polymer in a Banbury mixer. A variety of methods can be employed, such as from powder size or step of each polymer to blending and extrusion in an extruder to form blended chips or films.

Ethylene-vinyl alcohol copolymer, J: J IJ
Blends with amide may contain conventional ethylene-vinyl alcohol copolymers, nucleating agents, inorganic fillers, lubricants, slip agents, anti-blocking agents, and stabilizing agents that are blended with amide. agent, antistatic agent,
Appropriate amounts of various additives such as antifogging agents and pigments may be blended.

The main part of the container of the present invention is made of plastic having a multilayer structure. This multilayer structure consists of a polyester layer/sulfonic acid base-containing copolyester layer (adhesive layer)/initial blend layer of ethylene-vinyl alcohol copolymer and polyamide/sulfonic acid base-containing copolyester layer (adhesive layer). )/- It has a five-layer structure consisting of lyester layers.

Furthermore, as necessary, the following may be added: polyester layer/adhesive layer/initial blend layer/adhesive layer/polyester layer/adhesive layer/f:/P material layer initial adhesive layer/polyester layer. It may have a nine-layer structure.

#The thickness of the polyester layer is usually 3 to 4000 μm, preferably 5 to 1500 ATl, and the thickness of the first layer of the blend is usually 1 to 350 μm, preferably 2 to 2 μm.
00 μm, and the thickness of the sulfonic acid group-containing copolyester layer is usually 0.5 to 350 μm, preferably 2
or 200IRn.

The total thickness of the plastic with multilayer structure is 0.1
The amount is from 0.15 to 4, preferably from 0.15 to 1.

The ratio of the total thickness of the polyester layer to the thickness of the first layer of the blend is between 2:1 and 100:1. Especially 4:1 to 50
: A value within the range of 1 is preferable.

At least one polyester layer, preferably all polyester layers, and more preferably all polyester layers and the initial layer of the blend, of the multilayer plastic are oriented.

The stretching is performed at least in the l-axis direction, preferably in two mutually orthogonal directions.

From the viewpoint of strength and gas barrier properties, it is preferable that the film be stretched in two axial directions. The stretching ratio is usually 1.1
It is preferably 1.2 to 8 times, more preferably 1.5 to 7 times. Furthermore, the multilayer plastic can also be heat set depending on its intended use.

In the multilayer plastic of the present invention, the polyester layer and the initial blend layer of ethylene-vinyl alcohol copolymer and polyamide are bonded together by the sulfonate base-containing copolyester layer, and the sulfonate base M copolyester layer itself is stretched. At the same time, it has a high affinity adhesive force with polyester and with the first layer of the blend, so even if the multilayer plastic is stretched uniaxially or biaxially, there will be no delamination between the layers. It can be stretched sufficiently depending on the conditions.

Manufacturing method of container The stretched multilayer plastic container of the present invention having the excellent features described above is based on the second invention of the present application, that is, the inner and outer surface layers are made of polyester, and are made of a blend of ethylene-vinyl alcohol copolymer and polyamide. A sheet or preform having a multilayer structure consisting of an intermediate layer and a sulfonate base M coho IJ ester layer provided between the core surface layer and the intermediate layer is formed into a container shape under stretching conditions. It can be manufactured by a method for manufacturing stretched multilayer plastic containers.

In the N method of the present invention, when manufacturing a container from a sheet with a multilayer structure supporting the above structure, a sheet stretch molding method known per se is used, except that a multilayer structure sheet having the above structure is formed. Containers can be manufactured.

For example, an extruder equipped with a multilayer die is used to form a sheet of the multilayer plastic of the present invention, and the sheet is stretched uniaxially or biaxially, or without stretching, and then vacuum forming is performed. A container of a desired shape can be produced by stretch-molding by a method such as an air pressure molding method, a sheet blow molding method, a draw molding method, a drawing/iron molding method, a compression molding method, or the like.

The multilayer plastic sheet can also be produced by forming the polyester, the blend, and the sulfonate-containing copolyester separately into a sheet or film, and then stretching them uniaxially or biaxially, or without stretching them. After laminating them to form the structure of the invention, they are heat-pressed and bonded.
It can also be manufactured.

In the manufacturing method of the present invention, when manufacturing a container from a multilayered preform having the above-mentioned structure, a well-known blowing method is used, except that the multilayered structure and structural material of the preform are specified in the present invention. Containers can be manufactured by molding methods.

For example, by using three or more extruders to extrude the three types of molten resins used in the present invention into a laminated form as described above in a multilayer die, a multilayer parison is formed. Then, one end of the parison is closed to create a grown parison (preform), heated at a predetermined temperature for a predetermined time in a mold that fits the desired container shape, and then the axis (vertical) of the preform is ) There is a method in which the material is stretched in the horizontal direction and then laterally stretched in a mold using compressed air. The preform may be molded by injection molding.

Stretching conditions when manufacturing containers by stretch-molding sheets or preforms vary depending on the resin used, but stretching should be carried out at a temperature that is above the glass transition temperature and below the crystallization initiation temperature of the resin used. is preferably stretched in at least one axial direction, preferably in two axial directions, and the stretching ratio is usually 1.1 to 10 times, preferably 1.2 to 8 times,
More preferably, it is stretched 1.5 to 7 times so that the resin layer of the resulting container has molecular orientation.

Applications The multilayer plastic container of the present invention can be used for liquid or pasty foods and beverages, such as beer and other low-malt beverages, sake, fruit liquors such as whisky, shochu, and grape wine, and alcoholic beverages including various cocktails such as gin fizz: cola. −, Cysy,
Various carbonated drinks including plain soda; Straight juices such as lemon juice, orange juice, plum juice, boudoir juice, and strawberry juice; Fruit juice drinks including processed fruit juice drinks such as nectar; Tomato juice and various vegetable juices Synthetic beverages and vitamin-enriched drinks containing synthetic fruit juices using sugars such as sugar or fructose, citric acid, coloring agents, fragrances, etc., or adding vitamins as necessary; Lactic acid bacteria drink;
For example, seasonings such as pepper oil, sauce, vinegar, mirin, dressing, mayonnaise, ketchup, edible oil, miso, lard, ketchup; tofu, jam, putter, margarine, etc.; and liquid medicines, pesticides, and cosmetics. In addition, ketones such as acetone and methyl ethyl ketone; aliphatic hydrocarbons such as n-hexane and n-hexane; alicyclic hydrocarbons such as dichlorohexane; aromatic hydrocarbons such as benzene, toluene, and xylene. ; Chlorine-containing compounds such as carbon tetrachloride, ethane tetrachloride, ethylene tetrachloride; or various higher fatty acids; gasoline, kerosene, petroleum benzine, heavy oil, thinner, grease, silicone oil, light oil, machine oil: or liquefied freon (
There is little deterioration or weight loss, such as (product name of Devon Co., Ltd. in the United States),
It is useful as a container for storing each of the above-mentioned contents.

Example 1 Polyethylene terephthalate (PET) with an intrinsic viscosity of 1.06 at 30°C was layered with aliphatic polyester on the inner and outer surfaces, with a vinyl alcohol content of 69.0 mol, an ethylene content of 30.6 mol, and acetic acid. Vinyl residue strength 0.4
Molar ethylene-vinyl alcohol copolymer (EVO
H) and a caprolactam/hexamethylene diammonium adipate copolymer (nylon 6/6.6 copolymer, PA) with a caprolactam concentration of 91 moles at 70/30.
Blend (EVPA) mixed at the ratio of (weight ratio)
) as the intermediate layer, and the sodium sulfonate group as the polymer 1'O
Copolyester (S) containing 250 mmol of Og
An extruder with a built-in screw with a diameter of 65° and an effective length of 1820 mr is used as an extruder for PET, and an extruder with a built-in screw with a diameter of 5° and an effective length of 1400 m is used as an intermediate layer (
Extruder for blends), diameter 38 - effective length 950
An extruder with a built-in +m screw is used as an extruder for adhesive (sodium sulfonate-containing copolyester), and a molding device consisting of a die for 3 types and 5 layers, a sizing unit, a cooling tank, and a cutter is used to process PET. (outer layer) /
S/E'VPA/S/PET (inner layer)=z Olo
, a multilayer pipe having a thickness ratio of 2/110.215 was molded. Both ends are open and both ends of the 9-inch are heated and the neck and bottom are formed by compression molding to form a preform (
A preformed product) was obtained. This silicon foam was heated to 105° C. and then stretch-produced to obtain a foam having an internal volume of 1500 ml and a weight of 59.9 mm.

This is the oxygen gas permeability of the bottle (the cumulative amount of acid that permeated into the bottle during storage for one month at 37°C and 60ZRH after heat-sealing the mouth of the bottle with an aluminum foil/copolyester multilayer film in a nitrogen gas atmosphere). (measured with a tograph) and a rectangle (with the major axis in the bottle height direction) cut out from the bottle body wall to measure the interlayer peel strength.

Comparative Example 1 The ethylene-vinyl alcohol copolymer and nylon 6/6.6 copolymer blend of Example 1 had a vinyl alcohol content of 69.0 mol and an ethylene content of 30 mol.
Stretch blowing having the same materials, layer composition ratio, content, and weight as in Example 1, except that an ethylene-vinyl alcohol copolymer with a 6 mol ratio and a vinyl acetate residue of 1:rl and 0.4 mol ratio was used as the intermediate layer. The bottle was molded. The oxygen gas permeability and delamination strength of the shell wall were measured.

Comparative Example 2 Nylon 6/6 with a caprolactam concentration of 91 mmol was used instead of the sodium sulfonate group-containing copolyester of Example 1.
．． A stretched blow bottle was molded having the same materials, layer composition ratio, internal capacity, and weight as in Example 1, except that 6 copolymer was used as the adhesive. The oxygen permeability of this cell and the delamination strength of the shell wall were measured.

The above evaluation results of Example 1 and Comparative Examples 1 and 2 are summarized in Table 2.

Claims (4)

[Claims] (1) Consisting of inner and outer surface layers made of polyester, an intermediate layer made of a blend of ethylene-vinyl alcohol copolymer and polyamide, and a sulfonic acid group-containing copolyester layer provided between the surface layer and the intermediate layer. Stretched multilayer plastic container. (2) The multilayer plastic container according to claim 1, wherein at least the polyester layer is stretched in at least one axis and has molecular orientation. (3) The stretched multilayer plastic container according to claim 1, characterized in that the content of sulfonic acid groups in the sulfonic acid group-containing copolyester is 1 to 520 mmol per 100 g of said copolyester. (4) Consisting of inner and outer surface layers made of polyester, an intermediate layer made of a blend of ethylene-vinyl alcohol copolymer and polyamide, and a sulfonic acid group-containing copolyester layer provided between the surface layer and the intermediate layer. A method for producing a stretched multilayer plastic container, which comprises forming a multilayered sheet or preform into a container shape under stretching conditions.